Saturday, September 30, 2006
Friday, September 29, 2006
Thursday, September 28, 2006
中國人造太陽實驗成功放電
中國人造太陽實驗成功放電[17:21]
中國周四在合肥進行人造太陽實驗，首次成功放電。這是全球首個投入運行的全超導非圓截面核聚變實驗裝置。
人造太陽以探索無限而清潔的核聚變能源為目標。由於它和太陽產生能量的原理相同，都是熱核聚變反應，所以被外界稱為人造太陽。
所謂的人造太陽，就是在這台裝置的真空室內加入少量氫的同位素氘或氚，通過類似變壓器的原理使其產生等離子體，然後提高其密度、溫度使其發生聚變反應，反應過程中會產生巨大的能量。
1升海水提取的氘，在完全的聚變反應中釋放的能量，相當於燃燒300升汽油釋放的熱能。因此一旦這種技術成熟，建立了電站，就相當於建立了一個人造太陽。
中國周四在合肥進行人造太陽實驗，首次成功放電。這是全球首個投入運行的全超導非圓截面核聚變實驗裝置。
人造太陽以探索無限而清潔的核聚變能源為目標。由於它和太陽產生能量的原理相同，都是熱核聚變反應，所以被外界稱為人造太陽。
所謂的人造太陽，就是在這台裝置的真空室內加入少量氫的同位素氘或氚，通過類似變壓器的原理使其產生等離子體，然後提高其密度、溫度使其發生聚變反應，反應過程中會產生巨大的能量。
1升海水提取的氘，在完全的聚變反應中釋放的能量，相當於燃燒300升汽油釋放的熱能。因此一旦這種技術成熟，建立了電站，就相當於建立了一個人造太陽。
Tuesday, September 26, 2006
京深滬時興網上同居
京深滬時興網上同居
【明報專訊】源自台灣的「網絡同居」遊戲最近愈來愈受到深圳、上海、北京等大城市單身年輕白領追捧。內地著名網站「愛情公寓」(http://www.i-part.com.cn)最近數字顯示，目前在該網站搭建「公寓」的已逾260萬人，並有逾3萬對男女「入住」該網站公寓的「兩人小窩」，成為「網絡同居者」。
目前，內地具備「網絡同居」平台功能的網站有幾十個，每個人數少則幾千，多則上萬。
一網站逾260萬戶
深圳《晶報》報道，「網絡同居」是網上虛擬行為，即兩個網友根據網上提供的資料，互相同意後，在一間虛擬套房內，戀愛、結婚、生兒育女，一起煮飯、養寵物、澆灌花草，必要時還可撫養小孩。這一切只要關上電腦，就不復存在。「網絡同居」平台還可聊天、玩遊戲、上傳照片、語音對話、發郵件，像icq那樣聊天，也可像blog一樣發表心情日記。
這源自台灣的網絡遊戲幾年前進入內地後，迅速發展。去年上海「愛情公寓」創辦僅一個月，入住用戶已有10萬。昨日，「愛情公寓」網站首頁顯示，公寓住戶已超過260萬，有逾3萬間「兩人小窩」。這個數字還在持續更新。有報道稱，「愛情公寓」每日有五、六千新「居民」入住，參與者以20至25歲城市白領女性和大學生居多，其中不乏已婚知識型人士。
【明報專訊】源自台灣的「網絡同居」遊戲最近愈來愈受到深圳、上海、北京等大城市單身年輕白領追捧。內地著名網站「愛情公寓」(http://www.i-part.com.cn)最近數字顯示，目前在該網站搭建「公寓」的已逾260萬人，並有逾3萬對男女「入住」該網站公寓的「兩人小窩」，成為「網絡同居者」。
目前，內地具備「網絡同居」平台功能的網站有幾十個，每個人數少則幾千，多則上萬。
一網站逾260萬戶
深圳《晶報》報道，「網絡同居」是網上虛擬行為，即兩個網友根據網上提供的資料，互相同意後，在一間虛擬套房內，戀愛、結婚、生兒育女，一起煮飯、養寵物、澆灌花草，必要時還可撫養小孩。這一切只要關上電腦，就不復存在。「網絡同居」平台還可聊天、玩遊戲、上傳照片、語音對話、發郵件，像icq那樣聊天，也可像blog一樣發表心情日記。
這源自台灣的網絡遊戲幾年前進入內地後，迅速發展。去年上海「愛情公寓」創辦僅一個月，入住用戶已有10萬。昨日，「愛情公寓」網站首頁顯示，公寓住戶已超過260萬，有逾3萬間「兩人小窩」。這個數字還在持續更新。有報道稱，「愛情公寓」每日有五、六千新「居民」入住，參與者以20至25歲城市白領女性和大學生居多，其中不乏已婚知識型人士。
mathematical guide
http://ebooksclub.org/?module=showThread&id=20741
About This Guide
Why this Guide
This guide was created in an effort to classify the most important books in Mathematics here at ebooksclub.org. ebooksclub categories is so broad that it's almost inconvenient, but when you look for a certain topic in the many subtopics of mathematics, things gets little messy.
What is this Guide *NOT
This is not an exhaustive list of all Mathematics books at ebooksclub, it only highlights the famous, standard, helpful books around here. If you intend to search for a specific mathematics book, please refer to ebooksclub.org search facility.
Criticism
Please, your constructive criticism is all welcomed, but please this work is still requires much time and energy, for now I classify books for Top Level topics of MSC classification and it's of course still
Under Construction
You're welcome to suggest new books, correct classifications and all that.
About the classification
I use the AMS(Americal Mathematical Society)'s MSC 2000(Mathematical Subject Classification).
However I had to drift a little to include broad topics such as the so called College Algebra, College Geometry and all that.
The MSC classification is as the following
* 00: General material including elementary mathematics
* 01: History and biography
* 03: Mathematical logic and foundations
* 05: Combinatorics and graph theory
* 06: Order, lattices, ordered algebraic structures
* 08: General algebraic systems
* 11: Number theory
* 12: Field theory and polynomials
* 13: Commutative rings and algebras
* 14: Algebraic geometry
* 15: Linear and multilinear algebra; matrix theory
* 16: Associative rings and algebras
* 17: Nonassociative rings and algebras
* 18: Category theory, homological algebra
* 19: K-theory
* 20: Group theory and generalizations
* 22: Topological groups, Lie groups
* 26: Real functions and elementary calculus
* 28: Measure and integration
* 30: Functions of a complex variable
* 31: Potential theory
* 32: Several complex variables and analytic spaces
* 33: Special functions including trigonometric functions
* 34: Ordinary differential equations
* 35: Partial differential equations
* 37: Dynamical systems and ergodic theory
* 39: Difference and functional equations
* 40: Sequences, series, summability
* 41: Approximations and expansions
* 42: Fourier analysis
* 43: Abstract harmonic analysis
* 44: Integral transforms, operational calculus
* 45: Integral equations
* 46: Functional analysis
* 47: Operator theory
* 49: Calculus of variations and optimal control; optimization
* 51: Geometry, including classic Euclidean geometry
* 52: Convex and discrete geometry
* 53: Differential geometry
* 54: General topology
* 55: Algebraic topology
* 57: Manifolds and cell complexes
* 58: Global analysis, analysis on manifolds
* 60: Probability theory and stochastic processes
* 62: Statistics
* 65: Numerical analysis
* 68: Computer science
* 70: Mechanics of particles and systems
* 74: Mechanics of deformable solids
* 76: Fluid mechanics
* 78: Optics, electromagnetic theory
* 80: Classical thermodynamics, heat transfer
* 81: Quantum Theory
* 82: Statistical mechanics, structure of matter
* 83: Relativity and gravitational theory
* 85: Astronomy and astrophysics
* 86: Geophysics
* 90: Operations research, mathematical programming
* 91: Game theory, economics, social and behavioral sciences
* 92: Biology and other natural sciences
* 93: Systems theory; control
* 94: Information and communication, circuits
* 97: Mathematics education
* 00: General material including elementary mathematics
The Mathematics Subject Classification uses the classification 00 principally for non-subject-specific materials, such as conference proceedings, dictionaries, handbooks, and problem books. It also includes subject-specific items not typically noted in the Mathematical Reviews database by the AMS, such as elementary mathematics, recreational mathematics, and elementary applications of mathematics.
In general, such material is not included in this collection either. In many cases an occasion arises to treat an elementary question in a non-elementary way, and to so illustrate some branch of more advanced mathematics. When such an illustration is saved in this collection, it is classified according to the tool used (contrary to AMS guidelines for the use of the MSC!).
00A05: General mathematics
What Is Mathematics?: An Elementary Approach to Ideas and Methods
The Mathematics of Infinity: A Guide to Great Ideas (Good as a supplement)
Abel's Theorem in Problems and Solutions
Abel's Proof: An Essay on the Sources and Meaning of Mathematical Unsolvability
The Four-Color Theorem : History, Topological Foundations, and Idea of Proof
Kepler's Conjecture: How Some of the Greatest Minds in History Helped Solve One of the Oldest Math Problems in the World
College Algebra
Personally I don't consider this category as Algebra per se, it even discusses topics outside Algebra entirely as part of Algebra (such as Graphs, Sequences and so...)
College Algebra, Blitzer, Third Edition
College Algebra Demystified
Inner Algebra
Algebra Demystified
Schaum's Easy Outline Intermediate Algebra
501 Algebra Questions
Just in Time Algebra
Algebra Success In 20 Minutes A Day
Pre-Algebra Demystified
Schaum's Outline of College Mathematics
Problem Solving
Discusses techniques either explicitly or through problems, lots of categories overlap here, from Combinatorics and Algebra to Geometry and The Calculus, even Evolutionary Algorithms.
Problem-Solving Strategies *****
Problem Solving Through Problems *****
Mathematical Problems and Proofs : Combinatorics, Number Theory, and Geometry *****
Polynomials, Barbeau *****
Solving Equations With Physical Understanding
Engineering Problem Solving : A Classical Perspective
The IMO Compendium: A Collection of Problems Suggested for The International Mathematical Olympiads: 1959-2004 *****
How to Solve It: Modern Heuristics
103 Trigonometry Problems: From the Training of the USA IMO Team*****
How to Solve Word Problems in Calculus
Master Math : Solving Word Problems
* 01: History and biography
Unknown Quantity: A Real And Imaginary History of Algebra, Derbyshire
A Mathematician's Apology, Hardy
* 03: Mathematical logic and foundations
Set theory
Elements of Set theory, Enderton
Introduction to Set Theory, Hrbacek
Lectures in Logic and Set Theory, Tourlakis
Set Theory : Boolean-Valued Models and Independence Proofs, Bell
Mathematical Logic
Mathematical Logic, Ebbinghaus *****
A Mathematical Introduction to Logic, Enderton *****
Modal Logic, Chagrov
Language, Proof, and Logic
Incompleteness: The Proof and Paradox of Kurt Godel
Godel's Proof *****
Proof Writing
Usually discusses Set Theory, First order logic, and Number systems beside of course proof writing *techniques*.
Bridge to Abstract Mathematics
Math Proofs Demystified
Basic Concepts of Mathematics (No ISBN, Go to trillia.com)
Proofs from the Book
Note: This book isn't really about proof writing, but rather shows beautiful proofs in mathematics, should be used for inspiration.
* 05: Combinatorics and graph theory
TextBooks
Discrete Mathematics and its Applications, Rosen
Discrete and Combinatorial Mathematics: An Applied Introduction, Grimaldi
Discrete Mathematics, Lovasz
A First Course in Discrete Mathematics, Anderson
Discrete Mathematics for New Technology
Schaum's Outline of Discrete Mathematics
Handbook of Discrete and Combinatorial Mathematics
Concrete Mathematics, Knuth
Combinatorics
Combinatorics, Merris
Combinatorics : Topics, Techniques, Algorithms
Enumerative Combinatorics, Stanley
Handbook of Combinatorics, Graham
Combinatorial Species and Tree-like Structures
Graph theory
Fractional Graph Theory: A Rational Approach to the Theory of Graphs
Graph Theory With Applications
Algebraic Graph Theory
Graph Theory, Diestel
Eigenspaces of Graphs
Graph Algorithms and Applications
Modern Graph Theory, Bollobas
* 06: Order, lattices, ordered algebraic structures
* 08: General algebraic systems
* 11: Number theory
An Introduction to the Theory of Numbers, Hardy
Problems in Algebraic Number Theory
Analytic Number Theory, Newman
Transcendental Number Theory
Introduction to Analytic Number Theory, Apostol *****
Advanced Number Theory, Cohn
Elementary Methods in Number Theory, Nathanson
Analytic Number Theory: An Introductory Course
A Course in Number Theory and Cryptography
Number Theory, Shafarevich
The Book of Numbers, John Horton Conway *****
On Numbers and Games, John Horton Conway *****
Popular Level
Prime Obsession: Bernhard Riemann and the Greatest Unsolved Problem in Mathematics *****
* 12: Field theory and polynomials
Abstract Algebra(Undergraduate level):
A Survey of Modern Algebra, MacLange
Algebra I, Basic Notions of Algebra, Shafarevich
Abstract Algebra (3rd Edition), Dummit and Foote
Applications of Abstract Algebra with MAPLE, Klima
Modern Algebra with Applications, Gilbert
Lectures in Abstract Algebra: Basic Concepts, Jacobson
Schaum's Outline of Abstract Algebra
Abstract Algebra Textbooks(Graduate level)
Algebra, Lang
Advanced Modern Algebra, Rotman
Algebra: A Graduate Course, Isaacs
* 13: Commutative rings and algebras
Introduction to Commutative Algebra, Atiyah
Undergraduate Commutative Algebra, Reid
Computational Commutative Algebra 1
Commutative Algebra : with a View Toward Algebraic Geometry
Computational Aspects of Commutative Algebra: From a Special Issue of the Journal of Symbolic Computation 1989
Grobner Bases: A Computational Approach to Commutative Algebra
Combinatorial Commutative Algebra
Matrices over Commutative Rings
Commutative Algebra, Matsumura
* 14: Algebraic geometry
Undergraduate Algebraic Geometry, Reid
Algebraic Geometry : A First Course, Harris
Sheaves in Geometry and Logic : A First Introduction to Topos Theory
The Geometry of Schemes, Harris
Commutative Algebra : with a View Toward Algebraic Geometry
Algebraic Geometry, Bump
Algebraic Geometry 1: From Algebraic Varieties to Schemes
Algebraic Geometry, Hartshorne
Principles of Algebraic Geometry, Griffiths and Harris
Basic Algebraic Geometry 1: Varieties in Projective Space, Shafarevich
Basic Algebraic Geometry 2: Schemes and Complex Manifolds, Shafarevich
* 15: Linear and multilinear algebra; matrix theory
Linear Algebra (Abstract)
Finite Dimensional Vector Spaces
Linear Algebra, Hoffman
Linear Algebra Done right, Axler
Lectures in Abstract Algebra Vol 2 Linear Algebra, Jacobson
Linear Algebra : Gateway to Mathematics, Messer
Linear Algebra (Less Abstract, More Applications)
Linear Algebra and It's Applications, Strang
Applied Linear Algebra and Matrix Analysis, Shores
Schaum's Outline of Theory and Problems of Linear Algebra, Lipschutz
Matrix Analysis and Applied Linear Algebra, Meyer
Applied Numerical Algebra, Demmel
Applied Linear Algebra, Usmani
* 16: Associative rings and algebras
* 17: Nonassociative rings and algebras
* 18: Category theory, homological algebra
Categories for the Working Mathematician, MacLane
Abelian Categories: An Introduction to the Theory of Functors
Categories and functors, Pareigis
Methods of Homological Algebra
A Course in Homological Algebra
An Elementary Approach to Homological Algebra
* 19: K-theory
* 20: Group theory and generalizations
Linear Groups with an Exposition of Galois Field Theory
Group Rings, Crossed Products, and Galois Theory
The Classification of the Finite Simple Groups
The theory of groups, Kurosh
Problems in Group Theory, Dixon
* 22: Topological groups, Lie groups
Lie Groups, Lie Algebras, and Representations, Hall
Matrix Groups, Baker
Lectures on Lie Groups, Hsiang
* 26: Real functions and elementary calculus
Elementary Calculus
Topics in Calculus include Continuity, Differentiation, Integration, Sequences, Series. The Calculus is developed using basic results of Geometry and Algebra without usage of point set topology. Limits will be studies/used extensively (Formal epsilon delta proofs not usually discussed in detail). Basic results of Calculus will be studies on Algebraic functions (Polynomials, Rational, Power) and Elementary transcendental functions (Logariths, Exponentials, Trigonometrics). Applications to the physical sciences to illustrate the power of the Calculus. Some courses will also Analytic Geometry along the way. Multi Variable Calculus will mostly use 3D Geometry to develop intuition, further generalization to higher dimensions most likely will be studied in a later course (usually Global Analysis). Some Elementary Numerical methods will be discussed without further study of error analysis.
Calculus, Vol. 1. Apostol *****
Calculus, Vol. 2. Apostol *****
Foundations of Differential Calculus, Euler
A Course of Pure Mathematics, Hardy *****
Foundations of Analysis, Landau ****
Inside Calculus ****
Calculus, Stewart
Calculus : Early Transcendentals, Stewart ***
Calculus, Gilbert Strang (MIT)
Schaum's Outline of Beginning Calculus
Calculus unlimited
Elementary Calculus: An Infinitesimal Approach
Advanced Calculus, Loomis
On the Shoulders of Giants: A Course in Single Variable Calculus
Calculus (Cliffs Quick Review)
Calculus for the Utterly Confused
Calculus: Single Variable, Smith and Minton
Schaum's Outline of Theory and Problems of Advanced Calculus
Advanced Calculus, Kaplan
Advanced Calculus with Applications in Statistics
Calculus of Vector Functions
Calculus Demystified
Schaum's Outline of Advanced Calculus
Introductory Mathematical Analysis:
Studies The Calculus in a rigorous, formal and generalized manner. (not too generalization however)
Basic Elements of Real Analysis, Protter ***
Real Mathematical Analysis, Pugh *****
Principles of Mathematical Analysis, Rudin *****
Mathematical Analysis, Apostol *****
* 28: Measure and integration
The Lebesgue-Stieltjes Integral : A Practical Introduction
The Elements of Integration and Lebesgue Measure *****
Real and Complex Analysis, Rudin *****
Real Analysis, Royden *****
Real Analysis, Lang ***
Measure theory and fine properties of functions, Evans *****
Measure, Integral and Probability, Capinski ****
Measure and Integral, Wheeden and Zygmund *****
Schaum's Outline of Theory and Problems of Real Variables; Lebesgue Measure and Integration With Applications to Fourier Series **
* 30: Functions of a complex variable
Elementary Textbooks:
Complex Analysis (Theory of analytic functions) at a level suitable for Undergraduate study where real analysis rerequisites.
A First Course in Complex Analysis with Applications, Zill
Calculus with Complex Numbers, Reade
Standard Textbooks:
Complex Analysis, Ahlfors *****
A Course of Modern Analysis, Whittaker and Watson ***** (A Classic for Transcendenting functions)
Complex Analysis through examplex and Exercises, Pap
Functions of One Complex Variable, Conway
Complex Variables and the Laplace Transform for Engineers, LePage
* 31: Potential theory
* 32: Several complex variables and analytic spaces
Several Complex Variables, Schneider
* 33: Special functions including trigonometric functions
Special Functions, Andrews
Orthogonal Polynomials and Special Functions, Askey
On a Class of Incomplete Gamma Functions with Applications
Chebyshev Polynomials, Mason
* 34: Ordinary differential equations
Introductory Differential Equations
Elementary Differential Equations and Boundary Value Problems, Boyce and DiPrima
Schaum's Easy Outline Differential Equations
Handbook of Differential Equations, Zwillinger
Schaum's Outline of Differential Equations
Differential Equations Demystified
Ordinary Differential Equations, Arnold
Differential Equations, Dynamical Systems, and Linear Algebra, Hirsch
Ordinary Differential Equations, Hartman
Numerical Solutions for Differential Equations
Ordinary and Partial Differential Equation Routines in C, C++, Fortran, Java, Maple, and MATLAB
Scientific Computing and Differential Equations : An Introduction to Numerical Methods
Numerical Methods for Ordinary Differential Equations
Computer Methods for Ordinary Differential Equations and Differential-Algebraic Equations
Generalized Difference Methods for Differential Equations: Numerical Analysis of Finite Volume Methods
Numerical Methods for Elliptic and Parabolic Partial Differential Equations
Numerical Methods for Partial Differential Equations
Boundary and Finite Elements: Theory and Problems
* 35: Partial differential equations
An Introduction to Partial Differential Equations, Renardy
Introduction to Partial Differential Equations. : A Computational Approach
Lectures on Partial Differential Equations, V. I. Arnold
Partial Differential Equations, Evans
A First Course in Partial Differential Equations With Complex Variables and Transform Methods, Weinberger
Hilbert Space Methods for Partial Differential Equations
Nonlinear Partial Differential Equations for Scientists and Engineers
Partial Differential Equations and the Finite Element Method
Handbook of Linear Partial Differential Equations for Engineers and Scientists
Handbook of Nonlinear Partial Differential Equations
Partial Differential Equations, Volumes I, II, III by Taylor
Elementary Applied Partial Differential Equations: With Fourier Series and Boundary Value Problems
* 37: Dynamical systems and ergodic theory
Invitation to Dynamical Systems
Introduction to Dynamical Systems
Lectures on Chaotic Dynamical Systems
An Introduction to Chaotic Dynamical Systems *****
Dynamical Systems[img=http://www.ebooksclub.org/images/emoticons/icon_biggrin.gif a=biggrin][/img]ifferential Equations, Maps and Chaotic Behavior
Dynamical Systems, Birkhoff
Dynamical Systems and Ergodic Theory
Mathematics of dynamical systems
Chaos in Dynamical Systems
Introduction to Applied Nonlinear Dynamical Systems and Chaos
Fractals
Fractal Geometry : Mathematical Foundations and Applications, Falconer
Techniques in Fractal Geometry, Falconer
Fractal Geometry and Stochastics
* 39: Difference and functional equations
Difference Equations and Inequalities: Theory, Methods, and Applications
Lectures on Functional Equations and Their Applications
Difference Equations with Applications to Queues
Functional equations in a single variable, Kuczma
* 40: Sequences, series, summability
* 41: Approximations and expansions
Numerical Analysis 2000 : Approximation Theory
* 42: Fourier analysis
Fourier analysis studies approximations and decompositions of functions using trigonometric polynomials. Of incalculable value in many applications of analysis, this field has grown to include many specific and powerful results, including convergence criteria, estimates and inequalities, and existence and uniqueness results. Extensions include the theory of singular integrals, Fourier transforms, and the study of the appropriate function spaces. This heading also includes approximations by other orthogonal families of functions, including orthogonal polynomials and wavelets.
Fourier Analysis and Its Applications
Inside the FFT Black Box
Understanding the FFT
Understanding FFT Applications
Fourier Series, Transforms and Boundary Value Problems
Methods of Modern Mathematical Physics II: Fourier Analysis, Self-Adjointness
Fourier Analysis of Time Series : An Introduction
A Student's Guide to Fourier Transforms
Wavelets
An Introduction to Wavelets Through Linear Algebra
First Course in Wavelets with Fourier Analysis
Wavelets, Approximation, and Statistical Applications
A First Course on Wavelets
Ten Lectures on Wavelets, Daubechies
Abstract Harmonic Analysis of Continuous Wavelet Transforms
* 43: Abstract harmonic analysis
Harmonic Function Theory, Axler
An Introduction to Harmonic Analysis, Katznelson
An Introduction to Harmonic Analysis on Semisimple Lie Groups
Harmonic Analysis, Stein
* 44: Integral transforms, operational calculus
Integral Methods in Science and Engineering
* 45: Integral equations
Handbook of Integral Equations
Integral Equations: A Practical Treatment, from Spectral Theory to Applications
Integral Equations, Hochstadt
Volterra and Integral Equations of Vector Functions
Numerical Analysis 2000 : Ordinary Differential Equations and Integral Equations
* 46: Functional analysis
Here we mean the study of vector spaces of functions. This can include the abstract study of topological vector spaces as well as the study of particular spaces of interest, including attention to their bases (e.g. Fourier Analysis), and linear maps on them (e.g. Integral Transforms).
Functional Analysis Textbooks:
Functional analysis also called Modern Analysis is the study of infinite dimensional vector spaces (mainly Topological vector spaces), and mapping between these spaces (operators), transformations of these operators (e.g differential operators or self-adjoint operator), some approaches will associate algebraic structures (e.g ring structures such as Banach algebras and C-* algebras), an important application is Quantum mechanics.
Introductory Real Analysis, Kolmogorov ***
Functional analysis, Yoshida ***
Functional Analysis, Rudin *****
Functional Analysis in Modern Applied Mathematics, Curtain ***
Foundations of Modern Analysis, Friedman
Beginning Functional Analysis, Saxe *
Functional Analysis: An Introduction, Eidelman ****
Functional Analysis and Semigroups, Hille
A Course in Modern Analysis and its Applications, Cohen
Geometric Aspects of Functional Analysis, Milman
Applications
Physical questions (Especially quantum physics) helped in the development of Functional analysis, Modern Mathematical physics makes heavy use of functional analysis.
Methods of Modern Mathematical Physics, Functional Analysis, Reed *****
Functional Analysis in Mechanics, Lebedev
Operator Methods in Quantum Mechanics
Operator Algebras and Quantum Statistical Mechanics
Infinite Dimensional Groups and Algebras in Quantum Physics
Foundations of Quantum Mechanics *****
Infinite dimensional vector spaces
Topological vector spaces in general, Hilbert and Banach Spaces.
Topological Vector Spaces I, Koethe *****
Introduction to Hilbert Spaces with Applications *****
* 47: Operator theory
Theory of Operator Algebras, Takesaki
Theory of Linear Operators in Hilbert Space *****
Spectral Theory of Self-Adjoint Operators in Hilbert Space *****
Fundamentals of the Theory of Operator Algebras
Spectral Theory and Differential Operators
Lectures on Entire Operators, M.G. Kreins
An Invitation to C*-Algebras, Arveson
Hilbert C*-Modules : A Toolkit for Operator Algebraists
A Short Course on Spectral Theory *****
Spectral Theory and Nonlinear Functional Analysis
* 49: Calculus of variations and optimal control; optimization
Introduction To The Calculus Of Variations, Dacorogna
Calculus of Variations, Weinstock
Introduction to Optimization, Pedregal
Optimization, Lange
An Introduction to Optimization, Chong
Introduction to Linear Optimization
Convexity and Optimization in Rn
* 51: Geometry, including classic Euclidean geometry
51M: Real and complex geometry (also College Geometry)
Geometry Demystified
Fundamentals of College Geometry, Hemmerling
51N: Analytic and descriptive geometry
Exploring Analytical Geometry with Mathematica
Geometry Surveys
Introduction to Geometry, Coxeter *****
Geometry Revisited, Coxeter
Glimpses of Algebra and Geometry
Flavors of Geometry
Non-Euclidean Geometry, Coxeter
Geometry, Audin
* 52: Convex and discrete geometry
Handbook of Discrete and Computational Geometry
* 53: Differential geometry
Classical Differential Geometry:
Differential Geometry and Its Applications
Elements of Differential Geometry, Millman
Classical Differential Geometry of Curves and Surfaces
Modern Differential Geometry:
An Introduction to Differentiable Manifolds and Riemannian Geometry, Boothby
Natural Operations in Differential Geometry
Notes on differential geometry
A Panoramic View of Riemannian Geometry
The Geometry of Four-Manifolds
Gauge Theory and the Topology of Four-Manifolds
Index Theory, Coarse Geometry and Topology of Manifolds
Geometry, Topology and Physics
Curvature and Homology, Goldberg
Riemannian Geometry, do Carmo
Geometry and Billiards
Modern Differential Geometry for Physicists, Isham
Riemannian Geometry: A Beginner's Guide
* 54: General topology
Topology, Munkres *****
Elementary Concepts of Topology
Counterexamples in Topology *****
Lecture Notes on Elementary Topology and Geometry
Schaum's Outline of General Topology
* 55: Algebraic topology
A Concise Course in Algebraic Topology, May
Lectures on Algebraic Topology
Algebraic Topology: An Intuitive Approach, Sato
Algebraic Topology, Hatcher
Algebraic Topology from a Homotopical Viewpoint
Homotopical Algebra, Quillen
Algebraic Topology, Lefschetz
Simplicial Homotopy Theory
* 57: Manifolds and cell complexes
57M: Low-dimensional topology, including Knot theory
The Geometry and Physics of Knots
Knots and Surfaces, Gilbert
57N: Topological manifolds
Introduction to Topological Manifolds *****
57R: Differential topology
Differential Topology, Guillemin
Differential Topology, Hirsch
* 58: Global analysis, analysis on manifolds
Calculus on Manifolds, Spivak
Analysis on Manifolds, Munkres
Manifolds, Tensor Analysis, and Applications, Abraham
An Introduction to Differentiable Manifolds and Riemannian Geometry, Boothby
Introduction to Differentiable Manifolds, Lang
Foundations of differentiable Manifolds and Lie Groups, Warner
Differential Forms
Differential Forms : A Complement to Vector Calculus, Weintraub
Advanced Calculus : A Differential Forms Approach, Edwards
Differential Forms with Applications to the Physical Sciences
* 60: Probability theory and stochastic processes
60A: Foundations of probability theory
An Introduction to Probability Theory and Its Applications, Volume 1, Feller
Probability, Random Variables and Stochastic Processes, Papoulis
Schaum's Outline of Probability, Random Variables, and Random Processes
Introduction to Probability, Grinstead
Foundations of Modern Probability, Kallenberg
Probability Theory I and II, Loeve
Schaum's Outline of Theory and Problems of Probability and Statistics
Counterexamples in Probability
Probability : Theory and Examples
Probability and Statistical Inference
A Course in Probability Theory, Kai Lai Chung
Probability Theory : The Logic of Science
Probability: A Graduate Course
Basic Principles and Applications of Probability Theory, Skorokhod
Applied Probability, Lange
60Hxx Stochastic analysis
Stochastic Differential Equations, Oksendal
Stochastic Differential Equations and Applications
Introduction to Stochastic Integration
Stochastic Integration and Differential Equations, Protter
* 62: Statistics
* 65: Numerical analysis
Theoretical Numerical Analysis, A Functional Analysis Framework, Atkinson
Introduction to Numerical Analysis, Stoer
Numerical Analysis: The Mathematics of Scientific Computing
Elementary Numerical Analysis: An Algorithmic Approach
Numerical Analysis Using MATLAB and Spreadsheets
Applied Numerical Methods Using MATLAB
Numerical Methods Using MATLAB, Mathews
* 68: Computer science
* 70: Mechanics of particles and systems
* 74: Mechanics of deformable solids
* 76: Fluid mechanics
* 78: Optics, electromagnetic theory
* 80: Classical thermodynamics, heat transfer
* 81: Quantum Theory
* 82: Statistical mechanics, structure of matter
* 83: Relativity and gravitational theory
* 85: Astronomy and astrophysics
* 86: Geophysics
* 90: Operations research, mathematical programming
* 91: Game theory, economics, social and behavioral sciences
* 92: Biology and other natural sciences
* 93: Systems theory; control
* 94: Information and communication, circuits
* 97: Mathematics education
About This Guide
Why this Guide
This guide was created in an effort to classify the most important books in Mathematics here at ebooksclub.org. ebooksclub categories is so broad that it's almost inconvenient, but when you look for a certain topic in the many subtopics of mathematics, things gets little messy.
What is this Guide *NOT
This is not an exhaustive list of all Mathematics books at ebooksclub, it only highlights the famous, standard, helpful books around here. If you intend to search for a specific mathematics book, please refer to ebooksclub.org search facility.
Criticism
Please, your constructive criticism is all welcomed, but please this work is still requires much time and energy, for now I classify books for Top Level topics of MSC classification and it's of course still
Under Construction
You're welcome to suggest new books, correct classifications and all that.
About the classification
I use the AMS(Americal Mathematical Society)'s MSC 2000(Mathematical Subject Classification).
However I had to drift a little to include broad topics such as the so called College Algebra, College Geometry and all that.
The MSC classification is as the following
* 00: General material including elementary mathematics
* 01: History and biography
* 03: Mathematical logic and foundations
* 05: Combinatorics and graph theory
* 06: Order, lattices, ordered algebraic structures
* 08: General algebraic systems
* 11: Number theory
* 12: Field theory and polynomials
* 13: Commutative rings and algebras
* 14: Algebraic geometry
* 15: Linear and multilinear algebra; matrix theory
* 16: Associative rings and algebras
* 17: Nonassociative rings and algebras
* 18: Category theory, homological algebra
* 19: K-theory
* 20: Group theory and generalizations
* 22: Topological groups, Lie groups
* 26: Real functions and elementary calculus
* 28: Measure and integration
* 30: Functions of a complex variable
* 31: Potential theory
* 32: Several complex variables and analytic spaces
* 33: Special functions including trigonometric functions
* 34: Ordinary differential equations
* 35: Partial differential equations
* 37: Dynamical systems and ergodic theory
* 39: Difference and functional equations
* 40: Sequences, series, summability
* 41: Approximations and expansions
* 42: Fourier analysis
* 43: Abstract harmonic analysis
* 44: Integral transforms, operational calculus
* 45: Integral equations
* 46: Functional analysis
* 47: Operator theory
* 49: Calculus of variations and optimal control; optimization
* 51: Geometry, including classic Euclidean geometry
* 52: Convex and discrete geometry
* 53: Differential geometry
* 54: General topology
* 55: Algebraic topology
* 57: Manifolds and cell complexes
* 58: Global analysis, analysis on manifolds
* 60: Probability theory and stochastic processes
* 62: Statistics
* 65: Numerical analysis
* 68: Computer science
* 70: Mechanics of particles and systems
* 74: Mechanics of deformable solids
* 76: Fluid mechanics
* 78: Optics, electromagnetic theory
* 80: Classical thermodynamics, heat transfer
* 81: Quantum Theory
* 82: Statistical mechanics, structure of matter
* 83: Relativity and gravitational theory
* 85: Astronomy and astrophysics
* 86: Geophysics
* 90: Operations research, mathematical programming
* 91: Game theory, economics, social and behavioral sciences
* 92: Biology and other natural sciences
* 93: Systems theory; control
* 94: Information and communication, circuits
* 97: Mathematics education
* 00: General material including elementary mathematics
The Mathematics Subject Classification uses the classification 00 principally for non-subject-specific materials, such as conference proceedings, dictionaries, handbooks, and problem books. It also includes subject-specific items not typically noted in the Mathematical Reviews database by the AMS, such as elementary mathematics, recreational mathematics, and elementary applications of mathematics.
In general, such material is not included in this collection either. In many cases an occasion arises to treat an elementary question in a non-elementary way, and to so illustrate some branch of more advanced mathematics. When such an illustration is saved in this collection, it is classified according to the tool used (contrary to AMS guidelines for the use of the MSC!).
00A05: General mathematics
What Is Mathematics?: An Elementary Approach to Ideas and Methods
The Mathematics of Infinity: A Guide to Great Ideas (Good as a supplement)
Abel's Theorem in Problems and Solutions
Abel's Proof: An Essay on the Sources and Meaning of Mathematical Unsolvability
The Four-Color Theorem : History, Topological Foundations, and Idea of Proof
Kepler's Conjecture: How Some of the Greatest Minds in History Helped Solve One of the Oldest Math Problems in the World
College Algebra
Personally I don't consider this category as Algebra per se, it even discusses topics outside Algebra entirely as part of Algebra (such as Graphs, Sequences and so...)
College Algebra, Blitzer, Third Edition
College Algebra Demystified
Inner Algebra
Algebra Demystified
Schaum's Easy Outline Intermediate Algebra
501 Algebra Questions
Just in Time Algebra
Algebra Success In 20 Minutes A Day
Pre-Algebra Demystified
Schaum's Outline of College Mathematics
Problem Solving
Discusses techniques either explicitly or through problems, lots of categories overlap here, from Combinatorics and Algebra to Geometry and The Calculus, even Evolutionary Algorithms.
Problem-Solving Strategies *****
Problem Solving Through Problems *****
Mathematical Problems and Proofs : Combinatorics, Number Theory, and Geometry *****
Polynomials, Barbeau *****
Solving Equations With Physical Understanding
Engineering Problem Solving : A Classical Perspective
The IMO Compendium: A Collection of Problems Suggested for The International Mathematical Olympiads: 1959-2004 *****
How to Solve It: Modern Heuristics
103 Trigonometry Problems: From the Training of the USA IMO Team*****
How to Solve Word Problems in Calculus
Master Math : Solving Word Problems
* 01: History and biography
Unknown Quantity: A Real And Imaginary History of Algebra, Derbyshire
A Mathematician's Apology, Hardy
* 03: Mathematical logic and foundations
Set theory
Elements of Set theory, Enderton
Introduction to Set Theory, Hrbacek
Lectures in Logic and Set Theory, Tourlakis
Set Theory : Boolean-Valued Models and Independence Proofs, Bell
Mathematical Logic
Mathematical Logic, Ebbinghaus *****
A Mathematical Introduction to Logic, Enderton *****
Modal Logic, Chagrov
Language, Proof, and Logic
Incompleteness: The Proof and Paradox of Kurt Godel
Godel's Proof *****
Proof Writing
Usually discusses Set Theory, First order logic, and Number systems beside of course proof writing *techniques*.
Bridge to Abstract Mathematics
Math Proofs Demystified
Basic Concepts of Mathematics (No ISBN, Go to trillia.com)
Proofs from the Book
Note: This book isn't really about proof writing, but rather shows beautiful proofs in mathematics, should be used for inspiration.
* 05: Combinatorics and graph theory
TextBooks
Discrete Mathematics and its Applications, Rosen
Discrete and Combinatorial Mathematics: An Applied Introduction, Grimaldi
Discrete Mathematics, Lovasz
A First Course in Discrete Mathematics, Anderson
Discrete Mathematics for New Technology
Schaum's Outline of Discrete Mathematics
Handbook of Discrete and Combinatorial Mathematics
Concrete Mathematics, Knuth
Combinatorics
Combinatorics, Merris
Combinatorics : Topics, Techniques, Algorithms
Enumerative Combinatorics, Stanley
Handbook of Combinatorics, Graham
Combinatorial Species and Tree-like Structures
Graph theory
Fractional Graph Theory: A Rational Approach to the Theory of Graphs
Graph Theory With Applications
Algebraic Graph Theory
Graph Theory, Diestel
Eigenspaces of Graphs
Graph Algorithms and Applications
Modern Graph Theory, Bollobas
* 06: Order, lattices, ordered algebraic structures
* 08: General algebraic systems
* 11: Number theory
An Introduction to the Theory of Numbers, Hardy
Problems in Algebraic Number Theory
Analytic Number Theory, Newman
Transcendental Number Theory
Introduction to Analytic Number Theory, Apostol *****
Advanced Number Theory, Cohn
Elementary Methods in Number Theory, Nathanson
Analytic Number Theory: An Introductory Course
A Course in Number Theory and Cryptography
Number Theory, Shafarevich
The Book of Numbers, John Horton Conway *****
On Numbers and Games, John Horton Conway *****
Popular Level
Prime Obsession: Bernhard Riemann and the Greatest Unsolved Problem in Mathematics *****
* 12: Field theory and polynomials
Abstract Algebra(Undergraduate level):
A Survey of Modern Algebra, MacLange
Algebra I, Basic Notions of Algebra, Shafarevich
Abstract Algebra (3rd Edition), Dummit and Foote
Applications of Abstract Algebra with MAPLE, Klima
Modern Algebra with Applications, Gilbert
Lectures in Abstract Algebra: Basic Concepts, Jacobson
Schaum's Outline of Abstract Algebra
Abstract Algebra Textbooks(Graduate level)
Algebra, Lang
Advanced Modern Algebra, Rotman
Algebra: A Graduate Course, Isaacs
* 13: Commutative rings and algebras
Introduction to Commutative Algebra, Atiyah
Undergraduate Commutative Algebra, Reid
Computational Commutative Algebra 1
Commutative Algebra : with a View Toward Algebraic Geometry
Computational Aspects of Commutative Algebra: From a Special Issue of the Journal of Symbolic Computation 1989
Grobner Bases: A Computational Approach to Commutative Algebra
Combinatorial Commutative Algebra
Matrices over Commutative Rings
Commutative Algebra, Matsumura
* 14: Algebraic geometry
Undergraduate Algebraic Geometry, Reid
Algebraic Geometry : A First Course, Harris
Sheaves in Geometry and Logic : A First Introduction to Topos Theory
The Geometry of Schemes, Harris
Commutative Algebra : with a View Toward Algebraic Geometry
Algebraic Geometry, Bump
Algebraic Geometry 1: From Algebraic Varieties to Schemes
Algebraic Geometry, Hartshorne
Principles of Algebraic Geometry, Griffiths and Harris
Basic Algebraic Geometry 1: Varieties in Projective Space, Shafarevich
Basic Algebraic Geometry 2: Schemes and Complex Manifolds, Shafarevich
* 15: Linear and multilinear algebra; matrix theory
Linear Algebra (Abstract)
Finite Dimensional Vector Spaces
Linear Algebra, Hoffman
Linear Algebra Done right, Axler
Lectures in Abstract Algebra Vol 2 Linear Algebra, Jacobson
Linear Algebra : Gateway to Mathematics, Messer
Linear Algebra (Less Abstract, More Applications)
Linear Algebra and It's Applications, Strang
Applied Linear Algebra and Matrix Analysis, Shores
Schaum's Outline of Theory and Problems of Linear Algebra, Lipschutz
Matrix Analysis and Applied Linear Algebra, Meyer
Applied Numerical Algebra, Demmel
Applied Linear Algebra, Usmani
* 16: Associative rings and algebras
* 17: Nonassociative rings and algebras
* 18: Category theory, homological algebra
Categories for the Working Mathematician, MacLane
Abelian Categories: An Introduction to the Theory of Functors
Categories and functors, Pareigis
Methods of Homological Algebra
A Course in Homological Algebra
An Elementary Approach to Homological Algebra
* 19: K-theory
* 20: Group theory and generalizations
Linear Groups with an Exposition of Galois Field Theory
Group Rings, Crossed Products, and Galois Theory
The Classification of the Finite Simple Groups
The theory of groups, Kurosh
Problems in Group Theory, Dixon
* 22: Topological groups, Lie groups
Lie Groups, Lie Algebras, and Representations, Hall
Matrix Groups, Baker
Lectures on Lie Groups, Hsiang
* 26: Real functions and elementary calculus
Elementary Calculus
Topics in Calculus include Continuity, Differentiation, Integration, Sequences, Series. The Calculus is developed using basic results of Geometry and Algebra without usage of point set topology. Limits will be studies/used extensively (Formal epsilon delta proofs not usually discussed in detail). Basic results of Calculus will be studies on Algebraic functions (Polynomials, Rational, Power) and Elementary transcendental functions (Logariths, Exponentials, Trigonometrics). Applications to the physical sciences to illustrate the power of the Calculus. Some courses will also Analytic Geometry along the way. Multi Variable Calculus will mostly use 3D Geometry to develop intuition, further generalization to higher dimensions most likely will be studied in a later course (usually Global Analysis). Some Elementary Numerical methods will be discussed without further study of error analysis.
Calculus, Vol. 1. Apostol *****
Calculus, Vol. 2. Apostol *****
Foundations of Differential Calculus, Euler
A Course of Pure Mathematics, Hardy *****
Foundations of Analysis, Landau ****
Inside Calculus ****
Calculus, Stewart
Calculus : Early Transcendentals, Stewart ***
Calculus, Gilbert Strang (MIT)
Schaum's Outline of Beginning Calculus
Calculus unlimited
Elementary Calculus: An Infinitesimal Approach
Advanced Calculus, Loomis
On the Shoulders of Giants: A Course in Single Variable Calculus
Calculus (Cliffs Quick Review)
Calculus for the Utterly Confused
Calculus: Single Variable, Smith and Minton
Schaum's Outline of Theory and Problems of Advanced Calculus
Advanced Calculus, Kaplan
Advanced Calculus with Applications in Statistics
Calculus of Vector Functions
Calculus Demystified
Schaum's Outline of Advanced Calculus
Introductory Mathematical Analysis:
Studies The Calculus in a rigorous, formal and generalized manner. (not too generalization however)
Basic Elements of Real Analysis, Protter ***
Real Mathematical Analysis, Pugh *****
Principles of Mathematical Analysis, Rudin *****
Mathematical Analysis, Apostol *****
* 28: Measure and integration
The Lebesgue-Stieltjes Integral : A Practical Introduction
The Elements of Integration and Lebesgue Measure *****
Real and Complex Analysis, Rudin *****
Real Analysis, Royden *****
Real Analysis, Lang ***
Measure theory and fine properties of functions, Evans *****
Measure, Integral and Probability, Capinski ****
Measure and Integral, Wheeden and Zygmund *****
Schaum's Outline of Theory and Problems of Real Variables; Lebesgue Measure and Integration With Applications to Fourier Series **
* 30: Functions of a complex variable
Elementary Textbooks:
Complex Analysis (Theory of analytic functions) at a level suitable for Undergraduate study where real analysis rerequisites.
A First Course in Complex Analysis with Applications, Zill
Calculus with Complex Numbers, Reade
Standard Textbooks:
Complex Analysis, Ahlfors *****
A Course of Modern Analysis, Whittaker and Watson ***** (A Classic for Transcendenting functions)
Complex Analysis through examplex and Exercises, Pap
Functions of One Complex Variable, Conway
Complex Variables and the Laplace Transform for Engineers, LePage
* 31: Potential theory
* 32: Several complex variables and analytic spaces
Several Complex Variables, Schneider
* 33: Special functions including trigonometric functions
Special Functions, Andrews
Orthogonal Polynomials and Special Functions, Askey
On a Class of Incomplete Gamma Functions with Applications
Chebyshev Polynomials, Mason
* 34: Ordinary differential equations
Introductory Differential Equations
Elementary Differential Equations and Boundary Value Problems, Boyce and DiPrima
Schaum's Easy Outline Differential Equations
Handbook of Differential Equations, Zwillinger
Schaum's Outline of Differential Equations
Differential Equations Demystified
Ordinary Differential Equations, Arnold
Differential Equations, Dynamical Systems, and Linear Algebra, Hirsch
Ordinary Differential Equations, Hartman
Numerical Solutions for Differential Equations
Ordinary and Partial Differential Equation Routines in C, C++, Fortran, Java, Maple, and MATLAB
Scientific Computing and Differential Equations : An Introduction to Numerical Methods
Numerical Methods for Ordinary Differential Equations
Computer Methods for Ordinary Differential Equations and Differential-Algebraic Equations
Generalized Difference Methods for Differential Equations: Numerical Analysis of Finite Volume Methods
Numerical Methods for Elliptic and Parabolic Partial Differential Equations
Numerical Methods for Partial Differential Equations
Boundary and Finite Elements: Theory and Problems
* 35: Partial differential equations
An Introduction to Partial Differential Equations, Renardy
Introduction to Partial Differential Equations. : A Computational Approach
Lectures on Partial Differential Equations, V. I. Arnold
Partial Differential Equations, Evans
A First Course in Partial Differential Equations With Complex Variables and Transform Methods, Weinberger
Hilbert Space Methods for Partial Differential Equations
Nonlinear Partial Differential Equations for Scientists and Engineers
Partial Differential Equations and the Finite Element Method
Handbook of Linear Partial Differential Equations for Engineers and Scientists
Handbook of Nonlinear Partial Differential Equations
Partial Differential Equations, Volumes I, II, III by Taylor
Elementary Applied Partial Differential Equations: With Fourier Series and Boundary Value Problems
* 37: Dynamical systems and ergodic theory
Invitation to Dynamical Systems
Introduction to Dynamical Systems
Lectures on Chaotic Dynamical Systems
An Introduction to Chaotic Dynamical Systems *****
Dynamical Systems[img=http://www.ebooksclub.org/images/emoticons/icon_biggrin.gif a=biggrin][/img]ifferential Equations, Maps and Chaotic Behavior
Dynamical Systems, Birkhoff
Dynamical Systems and Ergodic Theory
Mathematics of dynamical systems
Chaos in Dynamical Systems
Introduction to Applied Nonlinear Dynamical Systems and Chaos
Fractals
Fractal Geometry : Mathematical Foundations and Applications, Falconer
Techniques in Fractal Geometry, Falconer
Fractal Geometry and Stochastics
* 39: Difference and functional equations
Difference Equations and Inequalities: Theory, Methods, and Applications
Lectures on Functional Equations and Their Applications
Difference Equations with Applications to Queues
Functional equations in a single variable, Kuczma
* 40: Sequences, series, summability
* 41: Approximations and expansions
Numerical Analysis 2000 : Approximation Theory
* 42: Fourier analysis
Fourier analysis studies approximations and decompositions of functions using trigonometric polynomials. Of incalculable value in many applications of analysis, this field has grown to include many specific and powerful results, including convergence criteria, estimates and inequalities, and existence and uniqueness results. Extensions include the theory of singular integrals, Fourier transforms, and the study of the appropriate function spaces. This heading also includes approximations by other orthogonal families of functions, including orthogonal polynomials and wavelets.
Fourier Analysis and Its Applications
Inside the FFT Black Box
Understanding the FFT
Understanding FFT Applications
Fourier Series, Transforms and Boundary Value Problems
Methods of Modern Mathematical Physics II: Fourier Analysis, Self-Adjointness
Fourier Analysis of Time Series : An Introduction
A Student's Guide to Fourier Transforms
Wavelets
An Introduction to Wavelets Through Linear Algebra
First Course in Wavelets with Fourier Analysis
Wavelets, Approximation, and Statistical Applications
A First Course on Wavelets
Ten Lectures on Wavelets, Daubechies
Abstract Harmonic Analysis of Continuous Wavelet Transforms
* 43: Abstract harmonic analysis
Harmonic Function Theory, Axler
An Introduction to Harmonic Analysis, Katznelson
An Introduction to Harmonic Analysis on Semisimple Lie Groups
Harmonic Analysis, Stein
* 44: Integral transforms, operational calculus
Integral Methods in Science and Engineering
* 45: Integral equations
Handbook of Integral Equations
Integral Equations: A Practical Treatment, from Spectral Theory to Applications
Integral Equations, Hochstadt
Volterra and Integral Equations of Vector Functions
Numerical Analysis 2000 : Ordinary Differential Equations and Integral Equations
* 46: Functional analysis
Here we mean the study of vector spaces of functions. This can include the abstract study of topological vector spaces as well as the study of particular spaces of interest, including attention to their bases (e.g. Fourier Analysis), and linear maps on them (e.g. Integral Transforms).
Functional Analysis Textbooks:
Functional analysis also called Modern Analysis is the study of infinite dimensional vector spaces (mainly Topological vector spaces), and mapping between these spaces (operators), transformations of these operators (e.g differential operators or self-adjoint operator), some approaches will associate algebraic structures (e.g ring structures such as Banach algebras and C-* algebras), an important application is Quantum mechanics.
Introductory Real Analysis, Kolmogorov ***
Functional analysis, Yoshida ***
Functional Analysis, Rudin *****
Functional Analysis in Modern Applied Mathematics, Curtain ***
Foundations of Modern Analysis, Friedman
Beginning Functional Analysis, Saxe *
Functional Analysis: An Introduction, Eidelman ****
Functional Analysis and Semigroups, Hille
A Course in Modern Analysis and its Applications, Cohen
Geometric Aspects of Functional Analysis, Milman
Applications
Physical questions (Especially quantum physics) helped in the development of Functional analysis, Modern Mathematical physics makes heavy use of functional analysis.
Methods of Modern Mathematical Physics, Functional Analysis, Reed *****
Functional Analysis in Mechanics, Lebedev
Operator Methods in Quantum Mechanics
Operator Algebras and Quantum Statistical Mechanics
Infinite Dimensional Groups and Algebras in Quantum Physics
Foundations of Quantum Mechanics *****
Infinite dimensional vector spaces
Topological vector spaces in general, Hilbert and Banach Spaces.
Topological Vector Spaces I, Koethe *****
Introduction to Hilbert Spaces with Applications *****
* 47: Operator theory
Theory of Operator Algebras, Takesaki
Theory of Linear Operators in Hilbert Space *****
Spectral Theory of Self-Adjoint Operators in Hilbert Space *****
Fundamentals of the Theory of Operator Algebras
Spectral Theory and Differential Operators
Lectures on Entire Operators, M.G. Kreins
An Invitation to C*-Algebras, Arveson
Hilbert C*-Modules : A Toolkit for Operator Algebraists
A Short Course on Spectral Theory *****
Spectral Theory and Nonlinear Functional Analysis
* 49: Calculus of variations and optimal control; optimization
Introduction To The Calculus Of Variations, Dacorogna
Calculus of Variations, Weinstock
Introduction to Optimization, Pedregal
Optimization, Lange
An Introduction to Optimization, Chong
Introduction to Linear Optimization
Convexity and Optimization in Rn
* 51: Geometry, including classic Euclidean geometry
51M: Real and complex geometry (also College Geometry)
Geometry Demystified
Fundamentals of College Geometry, Hemmerling
51N: Analytic and descriptive geometry
Exploring Analytical Geometry with Mathematica
Geometry Surveys
Introduction to Geometry, Coxeter *****
Geometry Revisited, Coxeter
Glimpses of Algebra and Geometry
Flavors of Geometry
Non-Euclidean Geometry, Coxeter
Geometry, Audin
* 52: Convex and discrete geometry
Handbook of Discrete and Computational Geometry
* 53: Differential geometry
Classical Differential Geometry:
Differential Geometry and Its Applications
Elements of Differential Geometry, Millman
Classical Differential Geometry of Curves and Surfaces
Modern Differential Geometry:
An Introduction to Differentiable Manifolds and Riemannian Geometry, Boothby
Natural Operations in Differential Geometry
Notes on differential geometry
A Panoramic View of Riemannian Geometry
The Geometry of Four-Manifolds
Gauge Theory and the Topology of Four-Manifolds
Index Theory, Coarse Geometry and Topology of Manifolds
Geometry, Topology and Physics
Curvature and Homology, Goldberg
Riemannian Geometry, do Carmo
Geometry and Billiards
Modern Differential Geometry for Physicists, Isham
Riemannian Geometry: A Beginner's Guide
* 54: General topology
Topology, Munkres *****
Elementary Concepts of Topology
Counterexamples in Topology *****
Lecture Notes on Elementary Topology and Geometry
Schaum's Outline of General Topology
* 55: Algebraic topology
A Concise Course in Algebraic Topology, May
Lectures on Algebraic Topology
Algebraic Topology: An Intuitive Approach, Sato
Algebraic Topology, Hatcher
Algebraic Topology from a Homotopical Viewpoint
Homotopical Algebra, Quillen
Algebraic Topology, Lefschetz
Simplicial Homotopy Theory
* 57: Manifolds and cell complexes
57M: Low-dimensional topology, including Knot theory
The Geometry and Physics of Knots
Knots and Surfaces, Gilbert
57N: Topological manifolds
Introduction to Topological Manifolds *****
57R: Differential topology
Differential Topology, Guillemin
Differential Topology, Hirsch
* 58: Global analysis, analysis on manifolds
Calculus on Manifolds, Spivak
Analysis on Manifolds, Munkres
Manifolds, Tensor Analysis, and Applications, Abraham
An Introduction to Differentiable Manifolds and Riemannian Geometry, Boothby
Introduction to Differentiable Manifolds, Lang
Foundations of differentiable Manifolds and Lie Groups, Warner
Differential Forms
Differential Forms : A Complement to Vector Calculus, Weintraub
Advanced Calculus : A Differential Forms Approach, Edwards
Differential Forms with Applications to the Physical Sciences
* 60: Probability theory and stochastic processes
60A: Foundations of probability theory
An Introduction to Probability Theory and Its Applications, Volume 1, Feller
Probability, Random Variables and Stochastic Processes, Papoulis
Schaum's Outline of Probability, Random Variables, and Random Processes
Introduction to Probability, Grinstead
Foundations of Modern Probability, Kallenberg
Probability Theory I and II, Loeve
Schaum's Outline of Theory and Problems of Probability and Statistics
Counterexamples in Probability
Probability : Theory and Examples
Probability and Statistical Inference
A Course in Probability Theory, Kai Lai Chung
Probability Theory : The Logic of Science
Probability: A Graduate Course
Basic Principles and Applications of Probability Theory, Skorokhod
Applied Probability, Lange
60Hxx Stochastic analysis
Stochastic Differential Equations, Oksendal
Stochastic Differential Equations and Applications
Introduction to Stochastic Integration
Stochastic Integration and Differential Equations, Protter
* 62: Statistics
* 65: Numerical analysis
Theoretical Numerical Analysis, A Functional Analysis Framework, Atkinson
Introduction to Numerical Analysis, Stoer
Numerical Analysis: The Mathematics of Scientific Computing
Elementary Numerical Analysis: An Algorithmic Approach
Numerical Analysis Using MATLAB and Spreadsheets
Applied Numerical Methods Using MATLAB
Numerical Methods Using MATLAB, Mathews
* 68: Computer science
* 70: Mechanics of particles and systems
* 74: Mechanics of deformable solids
* 76: Fluid mechanics
* 78: Optics, electromagnetic theory
* 80: Classical thermodynamics, heat transfer
* 81: Quantum Theory
* 82: Statistical mechanics, structure of matter
* 83: Relativity and gravitational theory
* 85: Astronomy and astrophysics
* 86: Geophysics
* 90: Operations research, mathematical programming
* 91: Game theory, economics, social and behavioral sciences
* 92: Biology and other natural sciences
* 93: Systems theory; control
* 94: Information and communication, circuits
* 97: Mathematics education
Monday, September 25, 2006
《短歌行》----曹操
对酒当歌，人生几何？ 譬如朝露，去日苦多。 慨当以慷，忧思难忘。 何以解忧？唯有杜康。 青青子衿，悠悠我心。 但为君故，沈吟至今。 呦呦鹿鸣，食野之苹。 我有嘉宾，鼓瑟吹笙。 明明如月，何时可掇？ 忧从中来，不可断绝。 越陌度阡，枉用相存。 契阔谈宴，心念旧恩。 月明星稀，乌鹊南飞， 绕树三匝，何枝可依？ 山不厌高，海不厌深。 周公吐哺，天下归心。
《短歌行》是汉乐府的旧题，属于《相和歌·平调曲》。这就是说它本来是一个乐曲的名称，这种乐曲怎么唱法，现在当然是不知道了。但乐府《相和歌·平调曲》中除了《短歌行》还有《长歌行》，唐代吴兢《乐府古题要解》引证古诗“长歌正激烈”，魏文帝曹丕《燕歌行》“短歌微吟不能长”和晋代傅玄《艳歌行》“咄来长歌续短歌”等句，认为“长歌”、“短歌”是指“歌声有长短”。我们现在也就只能根据这一点点材料来理解《短歌行》的音乐特点。《短歌行》这个乐曲，原来当然也有相应的歌辞，就是“乐府古辞”，但这古辞已经失传了。现在所能见到的最早的《短歌行》就是曹操所作的拟乐府《短歌行》。所谓“拟乐府”就是运用乐府旧曲来补作新词，曹操传世的《短歌行》共有两首，这里要介绍的是其中的第一首。
这首《短歌行》的主题非常明确，就是作者希望有大量人才来为自己所用。曹操在其政治活动中，为了扩大他在庶族地主中的统治基础，打击反动的世袭豪强势力，曾大力强调“唯才是举”，为此而先后发布了“求贤令”、“举士令”、“求逸才令”等；而《短歌行》实际上就是一曲“求贤歌”、又正因为运用了诗歌的形式，含有丰富的抒情成分，所以就能起到独特的感染作用，有力地宣传了他所坚持的主张，配合了他所颁发的政令。
对酒当歌，人生几何？譬如朝露，去日苦多。慨当以慷，幽思难忘。何以解忧，唯有杜康。 在这八句中，作者强调他非常发愁，愁得不得了。那么愁的是什么呢？原来他是苦于得不到众多的“贤才”来同他合作，一道抓紧时间建功立业。试想连曹操这样位高权重的人居然在那里为“求贤”而发愁，那该有多大的宣传作用。假如庶族地主中真有“贤才”的话，看了这些话就不能不大受感动和鼓舞。他们正苦于找不到出路呢，没有想到曹操却在那里渴求人才，于是那真正有才或自以为有才的许许多多人，就很有可能跃跃欲试，向他“归心”了。 “对酒当歌”八句，猛一看很象是《古诗十九首》中的消极调子，而其实大不相同。这里讲“人生几何”，不是叫人“及时行乐”，而是要及时地建功立业。又从表面上看，曹操是在抒个人之情，发愁时间过得太快，恐怕来不及有所作为。实际上却是在巧妙地感染广大“贤才”，提醒他们人生就象“朝露”那样易于消失，岁月流逝已经很多，应该赶紧拿定主意，到我这里来施展抱负。所以一经分析便不难看出，诗中浓郁的抒情气氛包含了相当强烈的政治目的。这样积极的目的而故意要用低沉的调子来发端，这固然表明曹操真有他的愁思，所以才说得真切；但另一方面也正因为通过这样的调子更能打开处于下层、多历艰难、又急于寻找出路的人士的心扉。所以说用意和遣词既是真切的，也是巧妙的。在这八句诗中，主要的情感特征就是一个“愁”字，“愁”到需要用酒来消解（“杜康”相传是最早造酒的人，这里就用他的名字来作酒的代称）。“愁”这种感情本身是无法评价的，能够评价的只是这种情感的客观内容，也就是为什么而“愁”。由于自私、颓废、甚至反动的缘故而愁，那么这愁就是一种消极的感情；反之，为着某种有进步意义的目的而愁，那就成为一种积极的情感。放到具体的历史背景中看，曹操在这里所表达的愁绪就是属于后者，应该得到恰当的历史评价。清人陈沆在《诗比兴笺》中说：“此诗即汉高《大风歌》思猛士之旨也。‘人生几何’发端，盖传所谓古之王者知寿命之不长，故并建圣哲，以贻后嗣。”这可以说基本上懂得了曹操发愁的含意；不过所谓“并建圣哲，以贻后嗣”还未免说得迂远。曹操当时考虑的是要在他自己这一生中结束战乱，统一全中国。与汉高祖唱《大风歌》是既有相通之处，也有不同之处的。
青青子衿，悠悠我心。但为君故，沈吟至今。呦呦鹿鸣，食野之苹。我有嘉宾，鼓瑟吹笙。 这八句情味更加缠绵深长了。“青青”二句原来是《诗经·郑风·子衿》中的话，原诗是写一个姑娘在思念她的爱人，其中第一章的四句是：“青青子衿，悠悠我心。纵我不往，子宁不嗣音？”（你那青青的衣领啊，深深萦回在我的心灵。虽然我不能去找你，你为什么不主动给我音信？）曹操在这里引用这首诗，而且还说自己一直低低地吟诵它，这实在是太巧妙了。他说“青青子衿，悠悠我心”，固然是直接比喻了对“贤才”的思念；但更重要的是他所省掉的两句话：“纵我不往，子宁不嗣音？”曹操由于事实上不可能一个一个地去找那些“贤才”，所以他便用这种含蓄的方法来提醒他们：“就算我没有去找你们，你们为什么不主动来投奔我呢？”由这一层含而不露的意思可以看出，他那“求才”的用心实在是太周到了，的确具有感人的力量。而这感人力量正体现了文艺创作的政治性与艺术性的结合。他这种深细婉转的用心，在《求贤令》之类的文件中当然无法尽情表达；而《短歌行》作为一首诗，就能抒发政治文件所不能抒发的感情，起到政治文件所不能起的作用。紧接着他又引用《诗经·小雅·鹿鸣》中的四句，描写宾主欢宴的情景，意思是说只要你们到我这里来，我是一定会待以“嘉宾”之礼的，我们是能够欢快融洽地相处并合作的。这八句仍然没有明确地说出“求才”二字，因为曹操所写的是诗，所以用了典故来作比喻，这就是“婉而多讽”的表现方法。同时，“但为君故”这个“君”字，在曹操的诗中也具有典型意义。本来在《诗经》中，这“君”只是指一个具体的人；而在这里则具有了广泛的意义：在当时凡是读到曹操此诗的“贤士”，都可以自认为他就是曹操为之沈吟《子衿》一诗的思念对象。正因为这样，此诗流传开去，才会起到巨大的社会作用。
明明如月，何时可掇？忧从中来，不可断绝。越陌度阡，枉用相存。契阔谈，心念旧恩。 这八句是对以上十六句的强调和照应。以上十六句主要讲了两个意思，即为求贤而愁，又表示要待贤以礼。倘若借用音乐来作比，这可以说是全诗中的两个“主题旋律”，而“明明如月”八句就是这两个“主题旋律”的复现和变奏。前四句又在讲忧愁，是照应第一个八句；后四句讲“贤才”到来，是照应第二个八句。表面看来，意思上是与前十六句重复的，但实际上由于“主题旋律”的复现和变奏，因此使全诗更有抑扬低昂、反复咏叹之致，加强了抒情的浓度。再从表达诗的文学主题来看，这八句也不是简单重复，而是含有深意的。那就是说“贤才”已经来了不少，我们也合作得很融洽；然而我并不满足，我仍在为求贤而发愁，希望有更多的“贤才”到来。天上的明月常在运行，不会停止（“掇”通“辍”，“晋乐所奏”的《短歌行》正作“辍”，即停止的意思）；同样，我的求贤之思也是不会断绝的。说这种话又是用心周到的表现，因为曹操不断在延揽人才，那么后来者会不会顾虑“人满为患”呢？所以曹操在这里进一步表示，他的求贤之心就象明月常行那样不会终止，人们也就不必要有什么顾虑，早来晚来都一样会受到优待。关于这一点作者在下文还要有更加明确的表示，这里不过是承上启下，起到过渡与衬垫的作用。
月明星稀，乌鹊南飞，绕树三匝，何枝可依？山不厌高，海不厌深，周公吐哺，天下归心。 “月明”四句既是准确而形象的写景笔墨，同时也有比喻的深意。清人沈德潜在《古诗源》中说：“月明星稀四句，喻客子无所依托。”这说明他看出了这四句是比喻，但光说“客子”未免空泛；实际上这是指那些犹豫不定的人才，他们在三国鼎立的局面下一时无所适从。所以曹操以乌鹊绕树、“何枝可依”的情景来启发他们，不要三心二意，要善于择枝而栖，赶紧到自己这一边来。这四句诗生动刻画了那些犹豫徬徨者的处境与心情，然而作者不仅丝毫未加指责，反而在浓郁的诗意中透露着对这一些人的关心和同情。这恰恰说明曹操很会做思想工作，完全是以通情达理的姿态来吸引和争取人才。而象这样一种情味，也是充分发挥了诗歌所特有的感染作用。最后四句画龙点睛，明明白白地披肝沥胆，希望人才都来归我，确切地点明了本诗的主题。“周公吐哺”的典故出于《韩诗外传》，据说周公自言：“吾文王之子，武王之弟，成王之叔父也；又相天下，吾于天下亦不轻矣。然一沐三握发，一饭三吐哺，犹恐失天下之士。”周公为了接待天下之士，有时洗一次头，吃一顿饭，都曾中断数次，这种传说当然是太夸张了。不过这个典故用在这里却是突出地表现了作者求贤若渴的心情。“山不厌高，海不厌深”二句也是通过比喻极有说服力地表现了人才越多越好，决不会有“人满之患”。所以陈沆说：“鸟则择木，木岂能择鸟？天下三分，士不北走，则南驰耳。分奔蜀吴，栖皇未定，若非吐哺折节，何以来之？山不厌土，故能成其高；海不厌水，故能成其深；王者不厌士，故天下归心。”（亦见《诗比兴笺》）这些话是很有助于说明本诗的背景、主题以及最后各句之意的。
总起来说，《短歌行》正象曹操的其它诗作如《蒿里行》、《对酒》、《苦寒行》等一样，是政治性很强的诗作，主要是为曹操当时所实行的政治路线和政策策略服务的；然而它那政治内容和意义却完全熔铸在浓郁的抒情意境之中，全诗充分发挥了诗歌创作的特长，准确而巧妙地运用了比兴手法，来达到寓理于情，以情感人的目的。在曹操的时代，他就已经能够按照抒情诗的特殊规律来取得预期的社会效果，这一创作经验显然是值得借鉴的。同时因为曹操在当时强调“唯才是举”有一定的进步意义，所以他对“求贤”这一主题所作的高度艺术化的表现，也应得到历史的肯定。
《短歌行》是汉乐府的旧题，属于《相和歌·平调曲》。这就是说它本来是一个乐曲的名称，这种乐曲怎么唱法，现在当然是不知道了。但乐府《相和歌·平调曲》中除了《短歌行》还有《长歌行》，唐代吴兢《乐府古题要解》引证古诗“长歌正激烈”，魏文帝曹丕《燕歌行》“短歌微吟不能长”和晋代傅玄《艳歌行》“咄来长歌续短歌”等句，认为“长歌”、“短歌”是指“歌声有长短”。我们现在也就只能根据这一点点材料来理解《短歌行》的音乐特点。《短歌行》这个乐曲，原来当然也有相应的歌辞，就是“乐府古辞”，但这古辞已经失传了。现在所能见到的最早的《短歌行》就是曹操所作的拟乐府《短歌行》。所谓“拟乐府”就是运用乐府旧曲来补作新词，曹操传世的《短歌行》共有两首，这里要介绍的是其中的第一首。
这首《短歌行》的主题非常明确，就是作者希望有大量人才来为自己所用。曹操在其政治活动中，为了扩大他在庶族地主中的统治基础，打击反动的世袭豪强势力，曾大力强调“唯才是举”，为此而先后发布了“求贤令”、“举士令”、“求逸才令”等；而《短歌行》实际上就是一曲“求贤歌”、又正因为运用了诗歌的形式，含有丰富的抒情成分，所以就能起到独特的感染作用，有力地宣传了他所坚持的主张，配合了他所颁发的政令。
对酒当歌，人生几何？譬如朝露，去日苦多。慨当以慷，幽思难忘。何以解忧，唯有杜康。 在这八句中，作者强调他非常发愁，愁得不得了。那么愁的是什么呢？原来他是苦于得不到众多的“贤才”来同他合作，一道抓紧时间建功立业。试想连曹操这样位高权重的人居然在那里为“求贤”而发愁，那该有多大的宣传作用。假如庶族地主中真有“贤才”的话，看了这些话就不能不大受感动和鼓舞。他们正苦于找不到出路呢，没有想到曹操却在那里渴求人才，于是那真正有才或自以为有才的许许多多人，就很有可能跃跃欲试，向他“归心”了。 “对酒当歌”八句，猛一看很象是《古诗十九首》中的消极调子，而其实大不相同。这里讲“人生几何”，不是叫人“及时行乐”，而是要及时地建功立业。又从表面上看，曹操是在抒个人之情，发愁时间过得太快，恐怕来不及有所作为。实际上却是在巧妙地感染广大“贤才”，提醒他们人生就象“朝露”那样易于消失，岁月流逝已经很多，应该赶紧拿定主意，到我这里来施展抱负。所以一经分析便不难看出，诗中浓郁的抒情气氛包含了相当强烈的政治目的。这样积极的目的而故意要用低沉的调子来发端，这固然表明曹操真有他的愁思，所以才说得真切；但另一方面也正因为通过这样的调子更能打开处于下层、多历艰难、又急于寻找出路的人士的心扉。所以说用意和遣词既是真切的，也是巧妙的。在这八句诗中，主要的情感特征就是一个“愁”字，“愁”到需要用酒来消解（“杜康”相传是最早造酒的人，这里就用他的名字来作酒的代称）。“愁”这种感情本身是无法评价的，能够评价的只是这种情感的客观内容，也就是为什么而“愁”。由于自私、颓废、甚至反动的缘故而愁，那么这愁就是一种消极的感情；反之，为着某种有进步意义的目的而愁，那就成为一种积极的情感。放到具体的历史背景中看，曹操在这里所表达的愁绪就是属于后者，应该得到恰当的历史评价。清人陈沆在《诗比兴笺》中说：“此诗即汉高《大风歌》思猛士之旨也。‘人生几何’发端，盖传所谓古之王者知寿命之不长，故并建圣哲，以贻后嗣。”这可以说基本上懂得了曹操发愁的含意；不过所谓“并建圣哲，以贻后嗣”还未免说得迂远。曹操当时考虑的是要在他自己这一生中结束战乱，统一全中国。与汉高祖唱《大风歌》是既有相通之处，也有不同之处的。
青青子衿，悠悠我心。但为君故，沈吟至今。呦呦鹿鸣，食野之苹。我有嘉宾，鼓瑟吹笙。 这八句情味更加缠绵深长了。“青青”二句原来是《诗经·郑风·子衿》中的话，原诗是写一个姑娘在思念她的爱人，其中第一章的四句是：“青青子衿，悠悠我心。纵我不往，子宁不嗣音？”（你那青青的衣领啊，深深萦回在我的心灵。虽然我不能去找你，你为什么不主动给我音信？）曹操在这里引用这首诗，而且还说自己一直低低地吟诵它，这实在是太巧妙了。他说“青青子衿，悠悠我心”，固然是直接比喻了对“贤才”的思念；但更重要的是他所省掉的两句话：“纵我不往，子宁不嗣音？”曹操由于事实上不可能一个一个地去找那些“贤才”，所以他便用这种含蓄的方法来提醒他们：“就算我没有去找你们，你们为什么不主动来投奔我呢？”由这一层含而不露的意思可以看出，他那“求才”的用心实在是太周到了，的确具有感人的力量。而这感人力量正体现了文艺创作的政治性与艺术性的结合。他这种深细婉转的用心，在《求贤令》之类的文件中当然无法尽情表达；而《短歌行》作为一首诗，就能抒发政治文件所不能抒发的感情，起到政治文件所不能起的作用。紧接着他又引用《诗经·小雅·鹿鸣》中的四句，描写宾主欢宴的情景，意思是说只要你们到我这里来，我是一定会待以“嘉宾”之礼的，我们是能够欢快融洽地相处并合作的。这八句仍然没有明确地说出“求才”二字，因为曹操所写的是诗，所以用了典故来作比喻，这就是“婉而多讽”的表现方法。同时，“但为君故”这个“君”字，在曹操的诗中也具有典型意义。本来在《诗经》中，这“君”只是指一个具体的人；而在这里则具有了广泛的意义：在当时凡是读到曹操此诗的“贤士”，都可以自认为他就是曹操为之沈吟《子衿》一诗的思念对象。正因为这样，此诗流传开去，才会起到巨大的社会作用。
明明如月，何时可掇？忧从中来，不可断绝。越陌度阡，枉用相存。契阔谈，心念旧恩。 这八句是对以上十六句的强调和照应。以上十六句主要讲了两个意思，即为求贤而愁，又表示要待贤以礼。倘若借用音乐来作比，这可以说是全诗中的两个“主题旋律”，而“明明如月”八句就是这两个“主题旋律”的复现和变奏。前四句又在讲忧愁，是照应第一个八句；后四句讲“贤才”到来，是照应第二个八句。表面看来，意思上是与前十六句重复的，但实际上由于“主题旋律”的复现和变奏，因此使全诗更有抑扬低昂、反复咏叹之致，加强了抒情的浓度。再从表达诗的文学主题来看，这八句也不是简单重复，而是含有深意的。那就是说“贤才”已经来了不少，我们也合作得很融洽；然而我并不满足，我仍在为求贤而发愁，希望有更多的“贤才”到来。天上的明月常在运行，不会停止（“掇”通“辍”，“晋乐所奏”的《短歌行》正作“辍”，即停止的意思）；同样，我的求贤之思也是不会断绝的。说这种话又是用心周到的表现，因为曹操不断在延揽人才，那么后来者会不会顾虑“人满为患”呢？所以曹操在这里进一步表示，他的求贤之心就象明月常行那样不会终止，人们也就不必要有什么顾虑，早来晚来都一样会受到优待。关于这一点作者在下文还要有更加明确的表示，这里不过是承上启下，起到过渡与衬垫的作用。
月明星稀，乌鹊南飞，绕树三匝，何枝可依？山不厌高，海不厌深，周公吐哺，天下归心。 “月明”四句既是准确而形象的写景笔墨，同时也有比喻的深意。清人沈德潜在《古诗源》中说：“月明星稀四句，喻客子无所依托。”这说明他看出了这四句是比喻，但光说“客子”未免空泛；实际上这是指那些犹豫不定的人才，他们在三国鼎立的局面下一时无所适从。所以曹操以乌鹊绕树、“何枝可依”的情景来启发他们，不要三心二意，要善于择枝而栖，赶紧到自己这一边来。这四句诗生动刻画了那些犹豫徬徨者的处境与心情，然而作者不仅丝毫未加指责，反而在浓郁的诗意中透露着对这一些人的关心和同情。这恰恰说明曹操很会做思想工作，完全是以通情达理的姿态来吸引和争取人才。而象这样一种情味，也是充分发挥了诗歌所特有的感染作用。最后四句画龙点睛，明明白白地披肝沥胆，希望人才都来归我，确切地点明了本诗的主题。“周公吐哺”的典故出于《韩诗外传》，据说周公自言：“吾文王之子，武王之弟，成王之叔父也；又相天下，吾于天下亦不轻矣。然一沐三握发，一饭三吐哺，犹恐失天下之士。”周公为了接待天下之士，有时洗一次头，吃一顿饭，都曾中断数次，这种传说当然是太夸张了。不过这个典故用在这里却是突出地表现了作者求贤若渴的心情。“山不厌高，海不厌深”二句也是通过比喻极有说服力地表现了人才越多越好，决不会有“人满之患”。所以陈沆说：“鸟则择木，木岂能择鸟？天下三分，士不北走，则南驰耳。分奔蜀吴，栖皇未定，若非吐哺折节，何以来之？山不厌土，故能成其高；海不厌水，故能成其深；王者不厌士，故天下归心。”（亦见《诗比兴笺》）这些话是很有助于说明本诗的背景、主题以及最后各句之意的。
总起来说，《短歌行》正象曹操的其它诗作如《蒿里行》、《对酒》、《苦寒行》等一样，是政治性很强的诗作，主要是为曹操当时所实行的政治路线和政策策略服务的；然而它那政治内容和意义却完全熔铸在浓郁的抒情意境之中，全诗充分发挥了诗歌创作的特长，准确而巧妙地运用了比兴手法，来达到寓理于情，以情感人的目的。在曹操的时代，他就已经能够按照抒情诗的特殊规律来取得预期的社会效果，这一创作经验显然是值得借鉴的。同时因为曹操在当时强调“唯才是举”有一定的进步意义，所以他对“求贤”这一主题所作的高度艺术化的表现，也应得到历史的肯定。
第二代互聯網 中國技勝全球
第二代互聯網 中國技勝全球
【明報專訊】中國工程院前天(23日)授權公布，由中國研製的下一代互聯網主幹網核心技術通過國家驗收，這技術較第一代互聯網更大、更快、更及時、更安全和更方便，且令中國在二代互聯網徹底擺脫一代互聯網由「美國話事」的局面，並確定中國在下一代互聯網中領先地位。目前國際互聯網組織已決定以此為基礎，制定相應的國際標準。
新華社報道，「下一代互聯網主幹網」是中國在2003年啟動的國家重大科技攻關項目，由清華大學等25間高校共同承擔，2004年建成，在北京、上海、廣州進行聯網試行，目前已與全國20個城市167所高校科研機構互連，傳輸速度每秒2.5G到10G，是目前各國使用的第一代互聯網速的百多倍。
核心技術4突破
「下一代互聯網主幹網」在核心技術上有4項突破﹕開創性創建了世界上第一個純IPV6主幹網，加速世界互聯網發展步伐﹔在國際上首次提出真實原地址認證結構理論，為解決互聯網安全隱患提供重要保證﹔首次提出兩代互聯網過渡技術方案﹔具有自有知識產權的IPV6路由器(router)的大規模使用，將使中國今後在互聯網建設中徹底擺脫對國外設備的依賴。
IPV6全稱是「互聯網協議第6版」，目前第一代互聯網使用的IPV4是32位編碼，核心技術屬於美國，分配給中國的IP地址不到5000萬個。中國下一代互聯網採用IPV6是128位編碼，資源可無限擴充。
更快更安全方便
中國教育和科研計算機網專家委員會主任、清華大學教授吳建平表示，現在互聯網連接範圍有限，主要是電腦主機，而未來互聯網可連接所有人類社會可以連接的電器，較第一代互聯網更大、更快、更及時、更安全和更方便。
中國工程院院士鄔賀銓說，國外下一代互聯網的實驗網目前較多還停留在學術試驗方面，中國在這個網上採用的一些新技術，如真實IP地址、IPV4 over IPV6，以及基於下一代網的建設架構，很多都是國外現有實驗網所無，「我們還是處於領先的位置」。
據稱，目前國際互聯網組織已決定以此為基礎，成立兩個專門工作組，制定相應國際標準。
【明報專訊】中國工程院前天(23日)授權公布，由中國研製的下一代互聯網主幹網核心技術通過國家驗收，這技術較第一代互聯網更大、更快、更及時、更安全和更方便，且令中國在二代互聯網徹底擺脫一代互聯網由「美國話事」的局面，並確定中國在下一代互聯網中領先地位。目前國際互聯網組織已決定以此為基礎，制定相應的國際標準。
新華社報道，「下一代互聯網主幹網」是中國在2003年啟動的國家重大科技攻關項目，由清華大學等25間高校共同承擔，2004年建成，在北京、上海、廣州進行聯網試行，目前已與全國20個城市167所高校科研機構互連，傳輸速度每秒2.5G到10G，是目前各國使用的第一代互聯網速的百多倍。
核心技術4突破
「下一代互聯網主幹網」在核心技術上有4項突破﹕開創性創建了世界上第一個純IPV6主幹網，加速世界互聯網發展步伐﹔在國際上首次提出真實原地址認證結構理論，為解決互聯網安全隱患提供重要保證﹔首次提出兩代互聯網過渡技術方案﹔具有自有知識產權的IPV6路由器(router)的大規模使用，將使中國今後在互聯網建設中徹底擺脫對國外設備的依賴。
IPV6全稱是「互聯網協議第6版」，目前第一代互聯網使用的IPV4是32位編碼，核心技術屬於美國，分配給中國的IP地址不到5000萬個。中國下一代互聯網採用IPV6是128位編碼，資源可無限擴充。
更快更安全方便
中國教育和科研計算機網專家委員會主任、清華大學教授吳建平表示，現在互聯網連接範圍有限，主要是電腦主機，而未來互聯網可連接所有人類社會可以連接的電器，較第一代互聯網更大、更快、更及時、更安全和更方便。
中國工程院院士鄔賀銓說，國外下一代互聯網的實驗網目前較多還停留在學術試驗方面，中國在這個網上採用的一些新技術，如真實IP地址、IPV4 over IPV6，以及基於下一代網的建設架構，很多都是國外現有實驗網所無，「我們還是處於領先的位置」。
據稱，目前國際互聯網組織已決定以此為基礎，成立兩個專門工作組，制定相應國際標準。
Sunday, September 24, 2006
Saturday, September 23, 2006
毕业生申请保留户口、档案两年的政策精神
国务院办公厅转发国家教育部等四部委《关于进一步深化普通高等学校毕业生就业 制度改革有关问题的意见》，简称国务院19号文件的相关精神规定，在毕业离校前仍未 落实就业单位的应届毕业生可以延长择业期(不包括打算考研和自费出国留学的毕业生) ，从当年7月1日起，延长期限为两年。两年内与用人单位签订就业协议书、接受手续齐 备的毕业生，学校为其办理相关就业手续。其具体做法是： 1.当年毕业离校前仍未落实就业单位的京外生源应届毕业生须向学校申请，将其户 口和档案转至入学前户籍所在地，或保留在学校。北京生源毕业生毕业时应将户口转回 入学前户籍所在地，其档案由学校统一转至北京高校毕业生就业指导中心保管； 2. 户口和档案保存在学校的京外生源毕业生，应当与学校学生就业指导服务中心 签订协议，其户口和档案在学校保存的最长期限为两年。 3. 毕业生档案在校保存期间，两年内可免交档案保管费用，但毕业生应当接受学 校指定的档案管理机构。协议到期后，毕业生应当自行将户口和档案关系迁出。逾期不 办理或不与学校联系的，学校将其户口和档案迁至入学前户籍所在地。 4.根据北京市的有关规定，京外生源毕业生留京时间截止到当年的12月底；对于超 过上述期限在北京市落实工作单位的京外生源毕业生，由录取单位按照《北京市引进人 才和办理〈北京市工作寄住证〉的暂行办法》办理人才引进或北京市工作居住证，学校 不再为其办理派遣手续。 根据有关规定，对于到全校统一派遣时仍未落实单位的京外生源毕业生，其本人需 要向学校提出申请，将其户口、档案等关系转入入学前户籍所在地，或保留在学校两年 继续落实就业单位(打算出国、考研的毕业生不能申请将其户口、档案等关系保留在学校 )。毕业生在委托学校保管其户口档案期间，可以参加学校举办的各种招聘活动，但与学 校已经无隶属关系。
入户广州的最新政策
入户办理指南 一、 异地人才引进； 申办条件： 1、本科学历，有学士学位，年龄在35周岁以下； 2、大专学历，有中级以上职称，年龄在35周岁以下。 申办所需材料： l 档案所在单位详细地址； l 同意调出函、现实表现、计生证明（原档案单位出具）； l 企业营业执照副本复印件、劳动合同原件及复印件、人才引进表<单位盖公章>（ 聘用单位出具）； l 学历证、学位证或职称证原件（学历证、学位证需办理鉴定）； l 原户口本复印件（户主与本人两页）。 l 《人事代理手册》（小一寸近照）、《广州市引进人才呈报表》； 所需费用： 入户免费，需按500元/年的标准一次性收取三年的档案挂靠费1500元，及200元的人才引 进费，总额为1700元； 二、 应界大学生接收； 申办条件：大学本科，属国家统分生或委培生（须有学位证书）。 申办所需材料： l 单位组织机构代码证复印件。（单位提供） l 营业执照副本复印件。（单位提供） l 《大学生就业协议书》原件一式三份（加盖接收单位公章）。 l 《毕业生就业推荐表》原件一份。 l 身份证复印件一份。 l 已填写好并加盖接收单位公章的《人事代理手册》（手册我部提供）。 所需费用： 入户免费，按500元/年的标准一次性收取三年的档案挂靠费1500元 其它费用（均适合于上述两种）： 办理身份证费用：20元身份证办证工本费用、1元户口本工本费用； 如落南方人才集体户（地址：广州市黄埔大道668号中国南方人才市场广州市场）按20元 /月的标准一次性收取一年的户籍管理费240元/人。
出国留学或工作中国不再注销户口
中国公安 部8月7日公布户籍、交通、出入境及消防管理4方面30项便民措施，其中户籍管理推出7 项新措施，包括到西部工作的大学毕业生可选择将户口迁到工作地或保留原籍；大城市 高中级专才到小城镇或农村工作，可不迁户口；取消出国或出境工作及留学1年以上者注 销户口的规定等。其中最令外界关注的是，取消囚犯和劳教人员「注销城市户口」一项 。 开发西部者准不迁户 明报报道，公安部治安局副局长鲍遂献昨日说，中国实行常住地登记户口原则，公 民常住地如有变更，按规定应将户口迁移到现住地，但为了吸引更多大学生参与西部开 发，公安部调整有关原则，以除他们的後顾之忧。同时，到西部投资开发的各类人才也 可不迁户口，已迁者亦可迁回原地。 此外，由於很多城市考生不愿大学毕业後迁离城市，新例也规定入学时可自愿选择 是否办理户口迁移手续。 新例又规定，自即日起取消出国或出境1年以上者须注销户口的规定，以进一步方便 公民出国或出境。旧规定於1994年制定，规定公派或自费出国留学者在出国1年以上即要 注销户口。新规定取消以上限制，但出境定居者的户口则仍须注销，这些人再回国定居 或回国工作，须在30日内办理常住户口登记。 父母自选新生婴落户 另外，即日起新生婴儿户口可随父母自愿选择。官员说，此项政策自1998年推出後 ，并未得到切实执行，一些大城市设置了限制条件，民众对此极为不满意，如今重新公 布规定，有利於切实保护公民合法权益。官员强调，不管是否属於超额生育或非婚生育 的婴儿，新生婴儿落户皆随父母自愿选择，公安部门应该及时给予办理户口登记。 囚犯可保留原有户籍 新例最令人关注的是，取消了对被判徒刑、被决定劳动教养人员注销户口的规定。 过去数十年，公安部门为维护治安，分别於1958年、1981 年、1983 年和1994 年数度出 台、强化注销罪犯和劳教人员城市户口的办法，明确规定「期满後留场就业，不得回原 大中城市」，而这些规定一直受到海外质疑。公安部负责人昨天表示，保留囚犯和劳教 人员户口的新例旨在保护他们的合法权益，尊重和保护人权。
湖南省公安厅：全省至少有60万人身份证同号
http://news.tom.com 2006年09月22日 07时27分 来源:潇湘晨报 湖南省公安厅：全省至少有60万人身份证同号 核心提示 据省公安厅信息通信处最新统计数字，身份证号码完全相同、姓名不同的信息共计30万 余条。按照一条信息至少对应两人计算，全省至少有60万余人将受到同号的影响。 三个证明才能证明身份 今年54岁的胡卫平住在长沙市岳麓区窑坡山社区，具有20年驾龄。他现在开车时必须随 身携带三个证明身份的证件：老版第一代身份证（已过期），第二代身份证，以及当地 派出所出示的相关证明。 胡卫平第一代身份证是1986年办理的，到今年1月1日已过期。去年11月10日，胡办理了 第二代身份证号码。但在办理时他的身份证与别人同号，办证人员通知其更改身份证号 码。胡当时并没在意，此后他却频频遭遇同号的无尽困扰。驾驶证、房产证、护照、保 险等，许多与原身份证号相关的东西都将进行重新登记或更改，否则将无法认证。 麻烦还不止这些。办理完新版身份证不到1个月，他在一次开车的途中，便遭遇“伪证” 的尴尬。交警在例行检查中，发现胡出示的身份证号码与驾驶证号码不一致，怀疑其中 有一张是假证，于是扣押了车辆和证件。按通常情况，驾驶证与身份证必须是同一号码 ，这也符合国际通用惯例。 满腹委屈的胡拿着两张身份证到长沙市交警支队车管所，通过联网数据查证，他的驾驶 证、身份证均为合法证件，交警部门应该放车。车子虽然放出来了，但为了避免此类事 件继续发生，民警通知他应该在户籍所在地的派出所办个证明手续。 今年3月3日，长沙市公安局岳麓分局望月湖派出所为其出具了一纸证明：“4301035 807和430102195807系同一人。”此后胡出车时，须随身携带新老两 个身份证和一纸书面证明，避免出现同样的尴尬。 一个号码7个人使用 根据胡的陈述，他办理第二代身份证时工作人员告知，有7个人使用了与他一模一样的身 份证号码。 怎么会有如此多的同号？据省公安厅交警总队相关文件透露，省厅信息通讯处对综合信 息查询系统中的驾驶人信息与常住人口信息进行批量比对，发现身份证号码完全相同、 姓名不同的信息共计304454条。工作人员称，按照一条信息至少影响2个人计算，我省估 计有60多万人受到同号的影响。而随着第二代身份证的改新换代，这个问题将大量出现 。 省公安厅人口管理总队户政支队支队长刘昌顺告诉记者，身份证同号一般是2人一对，目 前还没有发现多人同号者，但理论上也有多人同号的可能。产生同号的根源将要追溯到 二十多年前，当时的人口户政工作是手工登记，许多工作人员为省麻烦，把同一乡镇的 同年月日的居民全编成了一个身份证号码，为现在的身份证同号埋下了隐患。 胡卫平有驾驶证，按照工作程序，只需把驾驶证号码进行更改就可以解决问题，但在12 个工作日内不能取得驾驶证，而且还须交纳换证的相关费用。胡说，不仅是要更换驾驶 证，还有护照、房产证、养老保险等与原来身份证号码有关的证件都必须进行更改，否 则就有可能带来麻烦。胡认为，这个问题是由国家相关部门的工作不到位引起的，带来 的损失也应由国家承担。 身份证同号连累驾驶证 胡卫平随身要带三证才能证明自己身份，但有人却为办不到证感到烦恼。朱先生是望城 县人，去年他已换了第二代身份证。3个月前，他买了辆新车准备办理驾驶证的时候，同 号让他卡了壳。 长沙市交警支队车管所工作人员告诉朱，由于我省已启用全国统一版机动车驾驶证管理 系统，他的身份证号码已有人“占用”并办理了驾驶证，而驾驶证号码必须与身份证号 码相同，所以目前无法给他办理，必须等身份证同号的对方将已有驾驶证注销掉，朱才 能够顺利办到驾驶证。 朱先生从交警支队获知，与他身份证同号的，是与他同一乡镇一名姓张的人。为了此事 ，朱多次与张联系，但对方就是不肯配合。“我已将交警下达的告知书当面交给了对方 ，但他就是不愿意去注销驾驶证，这让我无可奈何。”朱先生说。目前，无法办到驾驶 证的朱只好请人开车。 强制执行没有法律依据 同号的出现引起省公安厅领导的高度重视。省厅要求各地交警支队对辖区范围内的机动 车驾驶人身份证重错号人员进行告知，要求其到交警支队驾管所办理身份证号更改业务 。 而多位市民向本报反映，许多同号的人并不愿更改自己的身份证号码，主要是担心会给 自己带来更多麻烦。即便是交警支队下达了告知书，他们也不愿意前来办理驾驶证变更 号码的手续。朱先生认为，相关部门应出台强硬措施，迫使其他同号者来更改驾驶证号 码，否则他将长期无法办驾驶证，其损失可想而知。 长沙市交警支队车管所工作人员告诉记者，通过强制措施要求重号人员更改信息是没有 法律依据的，毕竟重号驾驶人员并没有违法。支队目前的任务是向重号驾驶人员下达告 知书，如果一段时期内仍存有大量重号驾驶员没有前来更改信息，他们将报请省厅交警 总队，采取适当措施来执行。 记者从省公安厅人口管理总队了解到，同号现象也不是唯独在我省存在，各地在启用全 国统一版机动车驾驶管理系统后，均出现不同程度的因身份证重号而造成驾驶人网上无 信息、新的驾驶证申请人无法办理机动车驾驶申请业务等问题。 记者了解到，由于这60万余同号人员只是全省人口总体中的少数，省公安厅人口管理总 队提醒市民，随着今后信息化程度越来越高，同号的公民应及早前往相关部门更改号码 ，以避免给自己带来更多的损失。 小知识 身份证号码的由来 据省公安厅人口管理总队工作人员介绍，身份证是证明公民身份的首要合法证件，其号 码是根据公民户籍所在地代码、出生年月日以及随机码组成。 我国第一代居民身份证是1986年开始集中办理的，当时主要由乡镇一级政府组织登记办 理，直到上世纪90年代初才开始由公安机关代为管理。第一代身份证号码由15位数组成 ，其中前6位数为省、市（地）、县（区）的代码，如胡卫平老版身份证中的“430103” 代表湖南省长沙市天心区。而随后的“5807”代表此公民的出生年月日是1952年8月 7日，而最后的“”是3个随机码。按照当时填写身份证号码的要求，在三个随机 号码中，有两位一般是乡镇的代码，而最后一位数字则代表公民的性别，男性为单数， 女性为偶数。 在同一个省市县，又是同年月日出生，其身份证号码的非“随机码”是固定的，而最后 的几位随机数字，则应视情况而定，应避免同号的产生。 “由于技术原因，当时编制身份证号码是通过手工进行的，而许多进行登记的工作人员 并没有完全按照规定去办，难免出现身份证同号的问题。”省公安厅人口管理总队一工 作人员说。 上世纪末，为避免“千年虫”的危害，身份证号码增加到18位数，采用了4位数取代原来 2位数的方式来说明出生年份，随机码也由原来的3位变成了4位，并在特殊情况下引用英 文字母进行区别。省公安厅人口管理总队户政支队支队长刘昌顺说，近几年，相关管理 部门把人口信息输入电脑数据库，进行联网管理，这更方便识别居民的个人身份。 胡卫平在变更身份证号码时，因其户籍所在地点发生了变化，身份证号码的第6个数字也 随之发生了变更。 原则 身份证同号如何纠错 今年7月，我省出台新的《常住户口登记管理暂行规定》。按照《规定》，公民身份号码 重号先由派出所协调双方，其中有一方愿放弃原号码的，公安机关将为其重新赋予新号 码。协调不成按以下原则纠正：在湖南省公安厅制证库中有记录优先保留原则。通过核 查制证库，凡是在制证库里有制证记录的人，其号码优先保留，无制证记录的人重新赋 号。迁移人员优先保留原则。考虑到迁移人员回原籍较难，在两人重号的情况下，未迁 移人员重新赋号，已迁移人员保留原号。两人都属迁移人员的，迁移距离较远的优先保 留其号码，迁移距离近的重新赋号。另一种原则是，谁的身份证签发日期是最近的，就 优先保留原号码。 省公安厅人口管理总队户政支队支队长刘昌顺解释，身份证签发日期最近的人，他的身 份信息也是最准确的。而签发日期较早的人的身份信息可能还有要更改的地方，重新赋 号的时候可以核对和更改自己可能有差错的信息。潇湘晨报记者 刘俊
Job-GE
感觉这两天RP值极低，仔细反省才想起来原来是一直许愿写写自己在GE的实习经历，到现在也没有实现。所以决定今天静下来，把自己这4个多月来，从做校园大使到实习这个过程中的感受和见闻写写，供大家参考，同时也为自己攒些RP，呵呵。 首先说说2006年4月22日在香格里拉饭店的Job Fair吧。那天有很多部门面试，当时的情况是说几天前已经有了电话面试，这个相当于二面了，来面试的人原则上都是初筛过关的。当然，之前的宣讲会上，负责校园招聘的HR也说过，当场还会接受同学们递交简历。实际上，当天除了提前通知过来面试的同学外，当场还是给了一些面试机会的。尤其是CTC中国研发中心，还有IMLP的项目都给了很多机会，基本上简历满足要求就会安排面试。 我当时是负责HealthCare面试秩序的，看到了许多同学递交简历。这里就说说我个人的感受吧，主要以技巧为主。 第一，是要专业对口 GE是一家以基础设施和工业产品为主的公司，EID的这个实习项目很大部分的位置都是要求专业背景的。这些要求在职位描述中都有提到。我当时帮HR收简历，好多同学就是把简历一投，连明确的方向都没有，这样的话被选中的概率很小。比如，HC主要是在医学成像方面要求比较多，HR在初步筛选简历的时候看的专业就是核物理或者由相关的图像分析经验，没有这些，基本上在当天的面试中是没有机会的。 第二，关于Marketing 现在大家都对Marketing感兴趣，但是GE的市场部门和大家理解的有所不同。基本上分为两种职能，一种叫Market Communication一般针对文科，尤其是新闻专业，主要是负责对外宣传，在新闻媒介上刊登消息。第二种是大家理解的Marketing部门，做战略或者宏观的东西，GE对于这部分人的要求很高的，目前一般需要5年左右的销售经验才能做市场。所以大家在投简历的时候需要认真阅读职位描述，Marketing也会招一部分实习生，不过对于专业也是要求比较多的，根据业务部门划分的比较细致（主要是因为GE是以技术为主的企业）。 第三，简历 因为帮助HR收简历，所以也收获一些经验。主要是教育背景、实习经历、社会工作应该平均分布一些。对于申请不同的职位，一定要有所侧重。尤其是很多工科同学的项目经验比较丰富，对于不同的职位，一定要从自己做过的项目中找到比较相关的部分。 另外，个人建议把中文简历放在英文上面。一般筛选简历的HR都是中国人，我想就算英语再好，也还是会偏向先阅读中文的材料的。不过英文简历也十分重要，如果没有或者写的不好的话，可能会没有面试机会 第四，其他 对于这种Job Fair，所谓霸王面的机会还是不少的。为了把握住这些机会，我建议大家首先了解下招聘的职位，多多准备简历（全国各大酒店复印打印都是10元一张，呵呵），简历一定好订好，准备一根笔，手机一直开着。对于GE这样的公司，着装上，男生单色衬衫+皮鞋+正装裤子就可以了。 还要说一句的就是，那天咱们学校的同学非常多，一度大家准备的声音比较大，而且拥挤，大家还是需要注意以下学校的形象，而且HR有时坐在门口收简历，给人的印象也不是很好。 总之，像GE这种基础设施制造和销售为主的公司，在投简历的过程中，我的感觉有这些经验。下面讲讲我的实习经历。 先从面试开始说起吧，面试的时候主要还是那些常规问题，自我介绍、个人经历等等。因为是我的第一个面试，所以非常紧张，加上对于这个职位又不是很清楚，所以发挥的不太好。不过，因为这个职位是销售助理，主要就是一些行政性的工作，所以，最后还是过了。 说起我这将近4个月的实习，感触还是很多的。从一开始为销售团队订酒店机票，到后来能够参与到部门大型的商业活动中，了解整个部门的运作，收获很多。 先说说我工作的部门，我在的部门是基础设施下面的油气集团（Infra Oil&Gas 和energy是平行的部门，其实，以前Oil&GAS是Energy下面的部门，去年年底部门调整后才独立出来。不过这个部门的HR和财务都是和Energy一起的，所以招聘的时候也在一起）。我的具体工作因销售团队当时的安排而定，联系过客户、做过文字翻译、为部门内部整理文件资料、申请财务流程等等。实习的时候我是大四，所以时间比较多，一周几乎是5天工作。其他部门的intern很多都是咱们学校研二的师姐，呵呵，就我一个男生，感觉比较......大家做的工作也根据Team的安排各有不同，不过基本上都是十分具体细致的工作（实习生的本质呀）。 这段实习经历总的来说让我体会到了在一家外企工作的感受，下面把收获总结总结。 首先是沟通，因为助理这个工作每天需要联系非常多的事情，和人沟通的技巧还是很重要的。因为企业文化的缘故，GE里的人都很Open，一般有问题都是会非常热心帮助的。工作一段后，感觉认识了很多人。虽然有的时候大家都很忙，但经常交流感觉很亲切。 培训是GE的特色，每天总能看见同事在电脑上上着自己老板或者HR为大家安排的课程，而且，经常会有全球负责培训的同事来办公室进行培训，也有很多机会外出培训。总之，大家都是不停的在学习。我参加了两次内部的培训。一次是听上海来的HR进行Presatation Skills Training。从这个培训中，我清楚地看到了GE的做事风格，同时也了解了周围的同事。另外一个是专门为intern准备的orientation。能有这么个机会真的非常难得，从GE Value到员工的职业发展，通过这次培训感觉对GE了解了很多。 诚信是GE的生命，我个人认为。因为我服务的是一个销售团队，可以看到这里做sales的不同。在GE，严格强调诚信原则，就是compliance and integrity。比如sales请人吃饭，各个部门的规定有所不同，因为我们这个部门涉及到一些大型国企和政府，要求每人每餐正常标准是200元人民币以下，而且，每顿饭必须要提前审批。Sales不能和客户唱卡拉OK，送礼品也有金额限制，超过200元或者总数过高就会有VP级的人物过问。不过，GE的产品还是买的很好，主要是因为技术比较强，在基础设施很多领域上没人能比，呵呵，工科的同学如果对研发有兴趣可以关注下GE的中国研发中心。 对于人员的发展，从对实习生的培训到我们最后结束时的report out，还有许多leadership program，感觉GE在员工发展上下了很大的功夫，很多的培训+内部的岗位轮换，机会还是非常多的。总的来说就是GE非常认同符合自己企业文化的员工。 还有就是对于人的心态上的锻炼，在学校的时候感觉工作以后做的事情是非常有挑战的，然而在实际工作中，总有许多小细节需要注意完成好，尤其是做销售的人，始终要保持好自己的状态，保持和客户的联系，了解客户的需求。这就需要不断的学习和激励，同时也需要毅力和积极的态度。感觉工作和做学生的变化还是很大的（突然特珍惜学生生活了）。 总之，在GE的实习感觉收获还是很多的，零七八碎写了一些，希望对大家有些作用。（对了，精华区里那个对于GE的介绍太老了，现在GE的中国总部在上海，北京是Energy Oil&Gas HealthCare Water的总部，其他的部门总部好像大多也在上海。现在GE China和日本的关系没有那么紧了，再过2、3年中国就是亚洲的发展核心部分了） 如果对GE感兴趣的话可以直接问我，站内消息就可以。另外，还要两位校园大使，chenxiyi和inano。呵呵，声明一下，我们三个发的intern消息都是由GE Corporate发给我们的，也有些消息是在GE实习或是工作的人发的，可能有时是部门需要比较急，而且需要清华的学生，所以直接post出来了，呵呵。 另外，做个提前预报，GE今年不会进行大规模的校园招聘了（因为会从Intern转，先考虑intern），不过在10月份会有一个小的seminar，应该会release出些招聘消息，感兴趣的话可以关注一下。 嗯，就这样吧，希望攒些RP。呵呵^_^
英语中的恋爱词汇
1. have a crush on 迷恋某人 A: I'm having this huge crush on Ted. I'm going to try and see if I can ask hi m out this weekend. A: 我最近好喜欢 Ted 喔! 我想看看能不能约他这个周末出来。 B: Well...But I heard that he is already seeing somebody. B: 嗯....但是我听说他已经有了交往的对象了ㄝ! 美国人关于交友的用词和我们有些不同。这里的 "he is seeing somebody" 有可能指他刚 正开始和某人交往, 也可能指他和对方已经交往了一阵子。 还有一个美国人常用来形容他们的「感情状况」的字是"relationship"。到目前为止, 我 还不能找到一个很贴切的中文来代替它。不过, 如果例句中的"...But I heard that he is already seeing somebody." 改成 "...But I heard that he is already is a seri ous relationship with somebody." 就惨了。因为那表示这个叫Ted 的男生不但是「死会 」了, 而且是「非常地死会」。 各位应该可以大致抓到它的意思吧。 2. play hard-to-get 欲擒故纵 A: So she stood you up last night. A: 结果, 她昨晚放你鸽子啦? B: Well, I guess she's trying to play hard-to-get. B: 嗯, 大概想跟我玩「欲擒故纵」的游戏吧! "stand someone up" 是「放某人鸽子」的意思。 "play hard-to-get" 也可以说成 "play tough-to-get"。 3. hook up 介绍、送作堆 A: Hey, how come you've never told me you have a cute sister... A: 嘿! 你为什么从来没告诉我你有一个这么漂亮可爱的妹妹? B: What are you trying to say? B: 你想说什么呢? A: Well, you can hook me up, maybe? A: 嗯..也许你可帮我介绍一下? B: No way. B: 休想! "How come?" 是口语上经常被用来代替"why"的字, 是「为什么」的意思。但是"how come " 跟"why"的用法是不同的。 用"how come"时, 句子的构造很接近中文: 如: "How come you didn't call me last night?" (你为什么昨晚没打电话给我呢?)。这句话如果换成用 "why"就须要用一般的问句型式, 而成 "Why didn't you call me last night?"了。 美国人对于亲属辈份关系的区分, 并不像我们那么清楚。这里的 "sister" 可能指「姊姊 」, 也可能指「妹妹」; 须要另外问才清楚。 "hook up" 是"connection"的意思, 相当于中文里的「介绍、认识」之类的词, 并不单指 男女之间的认识。比如某人正在找份工作, 他的朋友刚好认识比尔盖兹(Bill Gates)。他 就可以跟这位朋友说"Hey! Since you're a friend of Bill's, why don't you hook me up?" (嘿! 既然你是比尔的朋友, 帮我介绍一下吧!) 4. break up 分手 A: How are Bob and Pat doing? A: Bob 和 Pat 近来如何? B: They broke up last summer. B: 他们去年夏天分开了。 "break up" 是「关系中止」的意思, 不限于男女之间的关系。"break-up" 是分手的名词 形。如: "They had an ugly break-up." (他们很不愉快地分手了。) 5. date (男女间的)约会; 约会对象 A: Dude, did you see that babe over there? I'm dating her. A: 老兄!看见那边那个美女没有? 我正在跟她约会喔! B: Man, you're lucky. B: 你真是运气好! "babe" 是「令人垂涎」的美女或俊男。 「和某人约会」除了用 "date" , 还可以用 "romance"这个字。比如: "Beck and Ada ha ve been dating for years." 可以说成:"Beck and Ada have been romancing for year s.", 都是「Beck 跟 Ada 爱情长跑多年的意思」。 注意名词的" date" 和 "appointment" 不可混用?quot;appointment" 是男女以外的约会 , 如医生、工作面谈的约。万一你跟你的医生说:"I'd like to have a date with you." , 他可能会眼睛、嘴巴都张得很大。
在香港怎么买化妆品：SASA篇、卓悦篇
◆SASA篇 1、网购SASA 这是官方的话：在sasa.com定购货品运送到中国，除货物费用及每张单收取15美元的运费外（请注意，在sasa.com国际网站购物满350美元均可获免运费的送货服务。），您可能会被征关税。每个国家的税制浮动都很大，您可能需要负责这类附加费或税项，这视乎货品运送目的地的法例。 因为并非sasa.com收取这类附加费或税项，我们因此不能控制或预计这类收费的数目的多少，而且若被征收关税，只会通知收件人，而不会通知sasa.com的，所以我们亦没有相关资料，不便之处，恳请见谅。因每处地方的税务条例有很大分别，若想知道更详细的资料，我们建议您向您们的海关部门查询会比较正确和清楚。 mm如果一定要在sasa上网购的话，可以去办张信用卡，然后用美金支付，人民币还款，东西sasa可以帮你直接寄到内地的。不过他家的国际网站上东西都不算便宜的说，而且运费太贵啦～～～15刀哪，满250刀免运费。 要是你买的东西多，邮费就不算贵了，(他们是用速递形式的,一两天内就送到)。因为它是以订单计算，而不是重量计算的，一张订单15美金，要是多订就划算了。问题反而是关税，要是因为被抽查而要报税,莎莎是不管的。要是因此退货，莎莎不退钱之余，还会收手续费。这才是在国内上网买莎莎东西的最大问题。 我的一帮香港朋友也很少去 SASA,因为她们买化妆品是缺一件买一件, 折算下来一件也就便宜几十块, 以香港的消费水平来说也就一个商业午餐的价格.而且专柜购物环境好,服务态度比 SASA 好,产品的保障系数也高,还有赠品,如果固定用一个牌子,如会积分还有一大堆礼品...这样算下来去 SASA 的意义就不大了.倒是一些学生妹或低收入的会去那里买开架的护肤品或是彩妆.SASA 做最多生意海是国内游客, 大批量的买就感觉价格优势了。 在尖沙咀加连威老道是有一间龙城大药房,里面有不少化妆品,和莎莎一样,谁也不知道货源,所以答不上是不是一定是真的.不过,这店也开了很久了,有一定的捧场客.如果是喜欢去莎莎,卓越这些店买东西的,那龙城也可以考虑.它们是同一类型的店,只是规模沒有那么大而已。 在sasa或是卓悦都很便宜的，比专柜省，就是到专柜的价钱也大约是国内8折左右。但莎莎不是所有产品都比专柜或别的地方便宜的.一般的开架产品,如AVON,ZINO,露得清等等,就和WATSONS,MANNING等地方同价了,有些还比它们贵. 莎莎vip卡确是有九五折,不过,好象已经不再做新卡了,就是暂时不再发vip卡。 除了SASA还有卓悦，天使，都有很多门店。这些店比SASA的假货和过期货还要多，要小心点！ 看到有关报道说SASA是EA的一级总代理,猜想应该可以拿到比较好的进价.所以SASA的Sales很卖力的推销EA,不知道大家有没有这种感觉,在不同的Outlet里面,她们都不约而同的卖力推销EA的东东.还有Chen Yu,我的另外一个同事也是被推销买了Chen Yu的一款清洁面膜,好像HK$318。 在这里提醒大家,在SASA买东西要拿定主意,小心Sales们另有居心的推销哦.不过，EA的东西在SASA挺全的,还有很多促销活动,我觉得要是有人喜欢用EA的话,在SASA买挺不错的,她们的东西全而且不会有假货,并且推销得那么勤快,应该货比较新。但网上的信息和店里的有点出入,CD的Diorsnow精华网上写了320多,可是在SASA店里要370,有些店了还没有.一瓶Anna Sui的香水在这家店是104,到另外一家却是114,不知道是不是看错了.大家去买的时候最好拿定主意,有备而去,查好价格,打好单子，对了,要是有SASA的贵宾卡别忘了带,可以打95折的.我是没在SASA网购过，据说是20％的概率要交税 ，好象有买过的说都没有交过税的SASA 大部分商品都是专柜(HK)的 6~7 折,但SK-II 一般只打 8.5 折,专柜打九折,价格相差不多,专柜有赠品送。 护肤品一般是没有小样的，不过你若用中国银行的国际长城卡结帐，可打95折。我每次在SASA买,都只有送香水小样。 我第一次买H20就是在专卖店,小姐也说同样的话,但是后来几次,我都在莎莎买,品质完全一样,想到第一次多花了100港币,我到现在还后悔,而且莎莎在香港是上市公司,如果真是大张旗鼓的做水货,早就完蛋了,所以我还是相信莎莎了.至于价格问题不难理解,想想你身边的百货公司和家乐福,一样的东西就是不一样的价格吧,当然莎莎也有不足之处,她不像专柜可以详细解答产品有关问题,而且常常货不全.就是这样。 更正一个概念，水货并不等于假货。所谓的水货，指的是没有通过指定的代理商销售，出了问题代理商不负责，但品质是一样的。嘻嘻，老实讲，本人也是SASA的长期客户，每年都跑到香港SASA买些化妆品。要知道，她的价格比专柜的便宜不少啊，肯定会动心。但去SASA买东西的时候，真的要事前学会看生产批号，不然很容易中招。 在sasa买东西给小票的，就象超市那种，年月日都有的。 sasa是连锁店，价格统一，商品在不同时期会根据外部原因调整，变化幅度有多大就很难说了；几乎所有的品牌sasa网上和店里的价格一样，只有极少数的品牌店里的价格会比网上便宜一点点。 sasa卖的未必是假货，如果是，早被人投诉死了，但人家现在已经是上市公司了，而且在东南亚开了那么多家分店。。专柜的为什么会贵，其实化妆品开设柜台，本来就要支付很大一笔的上柜费，这个钱商家自然是加到商品里面去。我有一次问专柜的一jj，为什么隔壁sasa的同样产品比你们便宜至少1/3，她解释说他们的货都是原装进口，sasa货是大陆或者台湾加工的，还说她们的产品要浓一些，颜色又怎么怎么。。其实我比较了一下，可能是我老眼昏花，我真的看不出来有什么区别。而且港澳还有几家店买的东东比sasa还便宜呢。但不一样门庭若市。 支付也是问题呢，得有VISA或MASTER卡吧。而且邮费好象挺贵的。如果在sasa受气，你可以打香港旅游局的投诉电话，很有效的，香港现在的经济就靠内地人消费去支撑，她有什么资格这样做？你投诉，会有人找她麻烦的，这个偶知道，香港的特区政府对这个很重视的。 SASA的东西，不知道大家有没有留意，都是专柜打7折或者8折的，那么正常的价格下，东西都是正常的。但是偶尔也有，明明CHANEL打8折，但是某个产品居然对折卖了，就应该看清楚再买。而且SASA的东西是有尾货，尾货大多卖的比平时要便宜。一般的东西都是好的，否则SASA也不会开到今天而且在香港寸土寸金的地方，开到那么多家，是个很大的上市公司。但是我在SASA，去过那么多次了，从来没有买过假货，也许是现在SASA变好了？至于以前，无法评论，至少现在是能肯定的。关于价格问题，因为SASA也是一个公司，也要赚钱。她开价一般是按照柜台价格打折计算，所以用美金计一定会比港币的要贵了。SASA的东西大多都是从代理手上来的（除了是自己总代理的东西），因为有时候货不卖完就可能拿不到第二年的代理权，所以那些公司就会直接用不亏的价格转给SASA保证自己下一年度的代理权。而且SASA有卖套装中的小样，包括应该赠送的套装也都卖了，这些都导致了SASA的价格比一般地方来的低。 我觉得买这种贵贵的最好去专柜，因为本来就很贵了专柜一般有活动的，在SASA我一般只买100左右一件的东西。 还有LANCOME之类的，因为便宜的厉害，而且批号容易看。其实算算专柜有活动，还经常买满能送，比SASA好：） 要是真的要到莎莎买东西,最好还是选一些比较大间的,在旺区的,例如旺角,尖沙咀,铜锣湾的会比较好,这类店因为买东西的人多,货的流量大,货品可能会比较新鲜.铜锣湾时代广场附近那间莎莎较大,货亦较齐,可以考虑。先说明一下，我只是说那间莎莎的店比较大，人流比较多，货品运转可能比较快，不代表那里买的都一定是没问题的产品。莎莎卖的毕竟是水货，货品不是从代理而来，总会有风险的，是否在莎莎购，看各人的喜好了。 我记得我曾经就批号的问题打电话问过el的专柜小姐，她说批号不代表生产日期，而且，.批号是经常转的.各地区都不一样的.每次返一批货回来后,就会按总公司发过来的的指示,输入计算机,所以,就算是她们自己,也要把盒上的BAR CODE过一次计算机,再看看瓶身上的资料,才知道是甚么时候进的货。要是从别的地方买回来的货,她们也不一定能查到批号.小姐告诉我,这一年所进的专柜货,已经改为4位的批号,别的地区,她就不知道了.要是她们说的属实，那批号也不代表甚幺了。而且，我们不是el公司的人，谁真正懂得批号的意思，举例说，批号 A51，谁知道EL公司是不是真有批号A51这些货？以上仅为资料提供,对于要看批号买东西的JM,请留意一下.好象有点危言耸听，不过，这确是我不在莎莎买东西的原因，因为到现在为止，一直都没能打听到这些水货店的进货的渠道，那么，还是小心为上。莎莎一般是购买她们自己代理的产品,才会送赠品的,小姐们的理由是她们卖的已经比专柜便宜,所以不可能再有赠品.莎莎代理的就不同,可以送些小样.所以,要是买la colline之类的产品,就千万别忘了问她们拿。 如果在SASA和卓越买会便宜一些，然后多问下有没有特价，有时候会捡到宝。上次我朋友帮我带回来一瓶雅顿的第五大道（30ML），猜下多少钱？80块港币！笑得我嘴都合不拢。那是刚好碰上卓越打特价。 ２、几家sasa的比较： 1.香港铜锣湾罗素街38号金朝阳中心37楼 Sa Sa Beauty Plus 2.铜锣湾启超道14号地下 3. 铜锣湾骆克道500号地下 4. 铜锣湾罗素街38号 5. 沙田新城市广场第1期3楼348-349号舖 2、3都很大，沙田的那家也很大而全（而且我感觉沙田的那家东西比CAUSEWAYBAY的要新鲜？）。 沙田那家sasa门口好像就是bus站，挺方便的：） 4. 铜锣湾罗素街38号 这个是时代广场对面的那家,我去过;刚翻了香港地图 3. 铜锣湾骆克道500号地下 这个应该是在SOGO旁边的那家（她家边上好象是家“卓悦”）店堂小 ◆其他购物地点及指南 1、免税店 免税店的价格是和外面的专柜一样的.当然,比莎莎贵,因为莎莎是水货.免税店内没有COVERMARK、sk11、贝佳斯.一般的品牌,如BIOTHERM、CLINIQUE,LANCOME,EL,CD,ANNA SUI、chanel,clarins等都是有的。 海港城对面的免税店，品牌全，品质又有保证，只是比莎莎略贵一点。 我到hk就几天，根本没有时间逛多远，就在时代广场转了转，觉得地铁站是非常好的地方，里面有间JOYCE买的都是好东西，boots也是在地铁站的屈臣氏里面发先的，一下就买齐，花钱的感觉真好. 2、卓悦bonjour 我觉得卓越便宜多了：）在hk.好象卓悦每周都有特价的货品。它家的东西比SASA东西便宜，他主要卖的都是小一点的东西，有点象明星会，SASA卖的东西比较大牌一些。但还是比较可靠的。他们都会推荐一些自己店利润比较高的牌子！别听SALES的就好了，买自己需要的。 3、屈臣氏 一般而言,屈臣氏和百货公司的专柜没有多大分别. 香港机场内的护肤品,价钱基本和市区内的专店一样. 很多watson里面也有很多大牌的产品（金钟太古广场里面有很大一家，铜锣湾也有）， 如CD, CM, SKII 等， 好象她们的价格比SASA贵一点， 但比专柜要便宜一点， 不知道是不是这样. 4、专店 要是在香港岛那边的,sogo是好选择,还有是皇室大厦的西武百货. 1）想买一些比较特别的产品,如nuxe之类的,可能就要去金钟的太古广场了. 2）我常去的是海港城和九龙塘那边的又一城。推荐又一城，布局比较合理，东西也比较全，而且坐车方便。海港城太大了，如果不熟悉的话走起来很累很乱。 3）买大牌去中环没错.时髦的,中等价位的去铜锣湾或者尖沙嘴,我个人偏好前者。 4）运动品牌可以去旺角,那里的酷男酷女看得我眼花缭乱。 5）如果要买便宜的,去女人街吧.10块钱就可以买到一件上衣,不过这样的衣服有必要千里迢迢跑到HK去买吗？而且，假货就属女人街泛滥. 6）购买金饰品可以去湾仔，很便宜的。
Friday, September 22, 2006
15年後3千萬人無老婆
15年後3千萬人無老婆[16:10]
新華社報道，按照中國公元兩千年人口普查的數據，到二零二零年，中國將有三千萬男人找不到老婆。
報道指出，自上世紀八零年代以來，中國出生人口男女性別比持續升高。據兩千年第五次中國人口普查結果顯示，中國出生人口男女性別比已達到一百一十七比一百，嚴重超出一百零三比一百零七的正常範圍。而二零零五年百分之一人口抽樣調查結果顯示，中國出生人口性別比又有所升高，達一百一十八點五八比一百。
中國人口和計劃生育委員會宣傳教育司司長張建近日在廣西開展全國「關愛女孩」行動萬里行活動，他表示，國家人口和計生委有意願爭取把抑制男女性別比例失調的「利益導向機制」納入全國性的政策範疇，可為解決中國出生人口性別比偏高的問題提供一個有效的治理途徑。
自二零零三年起，中國政府選擇性別失衡問題最為嚴重的二十四個縣試點「關愛女孩」行動，目的在通過廣泛深入地宣傳教育，逐步建立起有利於女孩及其家庭發展的利益導向機制。
三年來，這些地方政府採取一系列「利益導向」政策，幫助下一代全是女孩的家庭發展生產，為這樣的家庭提供養老、醫療等社會保障，保障女孩的受教育權等。
比如，下一代全是女孩的夫婦，在其六十歲以後，每人每年可獲得人民幣六百元的獎勵扶助金；獨生女家庭或者雙女孩家庭，可以優先獲得小額貸款；有的地區獨生女家庭或者雙女孩家庭的女孩在中考高考時還可以獲得一定程度的加分，甚至在就業時，同等條件下，女性優於男性錄用。
有關專家認為，「利益導向機制」可有效破解中國人的「養兒防老」的思想問題，但「傳宗接代」思想的破解還有待時日。
張建說，如果沒有「同等優先」和「利益導向機制」對女孩的利益進行保障，那麼重男輕女的思想還會繼續下去，這關乎女性的生命權、發展權，絕非小事。過去，中國人口問題主要是抓數量問題，現在要抓結構問題，這意味著中國開始統籌解決人口問題。
新華社報道，按照中國公元兩千年人口普查的數據，到二零二零年，中國將有三千萬男人找不到老婆。
報道指出，自上世紀八零年代以來，中國出生人口男女性別比持續升高。據兩千年第五次中國人口普查結果顯示，中國出生人口男女性別比已達到一百一十七比一百，嚴重超出一百零三比一百零七的正常範圍。而二零零五年百分之一人口抽樣調查結果顯示，中國出生人口性別比又有所升高，達一百一十八點五八比一百。
中國人口和計劃生育委員會宣傳教育司司長張建近日在廣西開展全國「關愛女孩」行動萬里行活動，他表示，國家人口和計生委有意願爭取把抑制男女性別比例失調的「利益導向機制」納入全國性的政策範疇，可為解決中國出生人口性別比偏高的問題提供一個有效的治理途徑。
自二零零三年起，中國政府選擇性別失衡問題最為嚴重的二十四個縣試點「關愛女孩」行動，目的在通過廣泛深入地宣傳教育，逐步建立起有利於女孩及其家庭發展的利益導向機制。
三年來，這些地方政府採取一系列「利益導向」政策，幫助下一代全是女孩的家庭發展生產，為這樣的家庭提供養老、醫療等社會保障，保障女孩的受教育權等。
比如，下一代全是女孩的夫婦，在其六十歲以後，每人每年可獲得人民幣六百元的獎勵扶助金；獨生女家庭或者雙女孩家庭，可以優先獲得小額貸款；有的地區獨生女家庭或者雙女孩家庭的女孩在中考高考時還可以獲得一定程度的加分，甚至在就業時，同等條件下，女性優於男性錄用。
有關專家認為，「利益導向機制」可有效破解中國人的「養兒防老」的思想問題，但「傳宗接代」思想的破解還有待時日。
張建說，如果沒有「同等優先」和「利益導向機制」對女孩的利益進行保障，那麼重男輕女的思想還會繼續下去，這關乎女性的生命權、發展權，絕非小事。過去，中國人口問題主要是抓數量問題，現在要抓結構問題，這意味著中國開始統籌解決人口問題。
Windows XP Boot Problems & Edits
http://www.kellys-korner-xp.com/win_xp_restart.htm
Windows XP Boot Problems & Edits
Windows XP Restarts When You Try to Shut Down Your Computer
When you shut down your Windows XP-based computer, your computer may restart instead of shutting down, and you may see a blue screen for just a moment before the computer restarts.
The behavior can occur if the following conditions exist:
You have "automatically restart" selected. (Press WinKey-Break, or (Start/Run/Sysdm.cpl), Advanced Tab, Start Up and Recovery/Settings/System Failure/Unmark "Automatically Restart"/Ok/Ok.
The Roxio Easy CD Creator 5.0 or Direct CD 5.0 program is installed on your computer.
Resolution:
To resolve this issue, contact Roxio or view the following Roxio Web site to download and install the updated driver for Easy CD Creator 5.0 for Windows XP: http://www.roxio.com. To work around this issue, uninstall Roxio Easy CD Creator or Direct CD.
Easy CD Creator 5.0 Does Not Function In Windows XP
When you attempt to use Easy CD Creator 5.0, you may see an error message that is similar to the following message on a blue screen, or your computer may become unstable:
Stop 0x00000050: PrtSeqRd deferencing null device object
Easy CD Creator 5.02b and earlier has not been tested or approved by Roxio for use on Windows XP.
As of October 22, 2001, the latest version for Easy CD Creator is version 5.02b; this version is known to have problems running on Windows XP. Easy CD driver updates from Roxio are available from the following Roxio Web site:
http://www.roxio.com/en/support/ecdc/ecdcupdates.jhtml
http://www.roxio.com/en/company/roxio_xp.jhtml
More Information:
Windows XP may encounter a problem during startup that results in a STOP error message. Depending on the system configuration, the error message on a blue screen may not be displayed long enough to record the error information. To gather important information about the STOP error message and to verify the cause:
Right-click My Computer, and then click Properties. On the Advanced tab, click Settings under Startup and Recovery.
Click to clear the Automatically restart check box under System failure, and then click OK. The error message on a blue screen should remain on the screen so you can record the error information.
Instantly Reboot Upon a System Fault
Start/Run/Regedit. Navigate to...
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl
In the right pane choose AutoReboot/Right Click/Modify. Change value to 0 to disable and 1 to enable.
Windows Hangs While Saving Your Settings
When you shut down your computer, Microsoft Windows XP may stop responding (hang) while the following message is displayed: Saving your settings. When this occurs, you may be able to move the mouse pointer, but when you press CTRL+ALT+DEL, nothing happens. This issue may occur only occasionally. Supported Fix: "Restarting Windows XP".
Modify Hung App Time
Start/Run/Regedit. Navigate to...
HKEY_CURRENT_USER\Control Panel\Desktop
In the right pane, choose HungAppTimeout/Right Click/Modify/Change Value/Exit/Reboot.
Force Program Exit
Start/Run/Regedit
HKEY_CURRENT_USER\Control Panel\Desktop In the right pane find, "AutoEndTasks" (Create if not present). Set the Value of 0 or delete it. No reboot needed.
Disable Error Reporting
Start/Settings/Control Panel/System/Advanced/Error Reporting/Disable.
Windows Boots without Warning!
By default when WinXP encounters a system failure, it reboots without warning. The setting that controls this can be changed:
Control Panel/System/Advanced/Settings (Startup & Recovery)/System Failure/Uncheck-Automatically Restart. To view the event log: Administrative Tools/Event Viewer or Start/Run/eventvwr.To bypass the BSOD altogether and enable the instant "Auto Reboot" feature: Start/Run/Regedit
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl. Right click on "AutoReboot", modify and change the value to 1. Exit, reboot. To disable set the value back to 0.
Windows® Online Crash Analysis
If you experience a blue screen crash event, or Stop error, while using Microsoft Windows XP, you can upload the error report for analysis. http://oca.microsoft.com/welcome.asp
By default when WinXP encounters a system failure, it reboots without warning. The setting that controls this can be changed:
Control Panel/System/Advanced/Settings (Startup & Recovery)/System Failure/Uncheck-Automatically Restart. To view the event log: Admistrative Tools/Event Viewer or Start/Run/eventvwr.
To bypass the BSOD altogether and enable the instant "Auto Reboot" feature, run Regedit and go to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl
Right click on "AutoReboot", modify and change the value to 1. Exit, reboot. To disable set the value back to 0.
Windows® Online Crash Analysis
If you experience a blue screen crash event, or Stop error, while using Microsoft Windows XP, you can upload the error report for analysis. http://oca.microsoft.com/welcome.asp
Force Exit
Start/Run/Regedit
HKEY_CURRENT_USER\Control Panel\Desktop
In the right pane find, "AutoEndTasks" (Create if not present). Set the Value of 0 or delete it. No reboot needed.
The Computer Continuously Restarts
When you start your computer, the Microsoft Windows XP start up screen appears, and then the computer restarts. The Windows XP logon screen does not appear. This error can occur if the Kernel32.dll file is missing or damaged.
To resolve this issue, use the Windows Recovery Console to extract a new copy of the Kernel32.dll file from the original Windows XP compact disc (CD). To do this, follow these steps:
1. Start the Recovery Console. If you do not have the Recovery Console installed, start it from the Windows XP compact disc (CD). To do this, follow these steps:
a. Insert the Windows XP CD and restart the computer. If prompted, select any options required to boot from the CD.
b. When the text-based part of Setup begins, follow the prompts; choose the repair or recover option by pressing R.
c. If you have a dual-boot or multiple-boot system, choose the installation that you need to access from the recovery console.
d. When prompted, type the Administrator password.
2. At the command prompt, type "cd system32" (without the quotation marks), and then press ENTER.
3. Type "ren kernel32.dll kernel32.old" (without the quotation marks), and then press ENTER.
4. Type "map" (without the quotation marks), and then press ENTER.
5. Note the drive letter assigned to the CD-ROM drive that contains the Windows XP CD. It is displayed in a format similar to the following: D: \Device\CdRom0
6. Type "expand\i386\kernel32.dl_" (without the quotation marks) (where is the drive letter of the CD-ROM drive that contains the Windows XP CD), and then press ENTER. For example:
Expand d:\i386\kernel32.dl_
Note the underscore character after the "L" in Kernel32.dl_
The following message appears: Kernel32.dll, 1 file(s) expanded.
7. Type "exit" (without the quotation marks). The computer restarts.
8. Remove the Windows XP CD and start the computer normally.
How to Install the Windows Recovery Console
Disable Error Checking at Startup
Start/Run/Regedit. In the right pane, delete this entry: BootExecute autocheck autochk*
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
Disable/Remove Serious Error Message Upon Boot
Start/Control Panel/System/Advanced/Performance/Settings/Advanced/Virtual Memory/Change/Set to 0. Reboot/Reset Pagefile to System Managed Size.
Disable Windows XP's Windows Tour Prompt for all Users
Start/Run/Regedit. Navigate to...
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Applets
In the right pane, locate Tour (if it doesn't exist, add it. Edit/New/Key. Then select New Value and set it to 0).
To set the same option for users, navigate to...and repeat the above steps.
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Applets
Disable Unnecessary Programs at Startup
Start/Run/Regedit. Right Click/Delete unnecessary programs listed here:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Runonce HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Disable or Enable Boot Defrag
Start/Run/Regedit. Navigate to...
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Dfrg\BootOptimizeFunction
Select Enable in the right pane/Right Click/Modify/Change Value to Y to enable, N to disable. Exit/Reboot.
Windows XP Boot Problems & Edits
Windows XP Restarts When You Try to Shut Down Your Computer
When you shut down your Windows XP-based computer, your computer may restart instead of shutting down, and you may see a blue screen for just a moment before the computer restarts.
The behavior can occur if the following conditions exist:
You have "automatically restart" selected. (Press WinKey-Break, or (Start/Run/Sysdm.cpl), Advanced Tab, Start Up and Recovery/Settings/System Failure/Unmark "Automatically Restart"/Ok/Ok.
The Roxio Easy CD Creator 5.0 or Direct CD 5.0 program is installed on your computer.
Resolution:
To resolve this issue, contact Roxio or view the following Roxio Web site to download and install the updated driver for Easy CD Creator 5.0 for Windows XP: http://www.roxio.com. To work around this issue, uninstall Roxio Easy CD Creator or Direct CD.
Easy CD Creator 5.0 Does Not Function In Windows XP
When you attempt to use Easy CD Creator 5.0, you may see an error message that is similar to the following message on a blue screen, or your computer may become unstable:
Stop 0x00000050: PrtSeqRd deferencing null device object
Easy CD Creator 5.02b and earlier has not been tested or approved by Roxio for use on Windows XP.
As of October 22, 2001, the latest version for Easy CD Creator is version 5.02b; this version is known to have problems running on Windows XP. Easy CD driver updates from Roxio are available from the following Roxio Web site:
http://www.roxio.com/en/support/ecdc/ecdcupdates.jhtml
http://www.roxio.com/en/company/roxio_xp.jhtml
More Information:
Windows XP may encounter a problem during startup that results in a STOP error message. Depending on the system configuration, the error message on a blue screen may not be displayed long enough to record the error information. To gather important information about the STOP error message and to verify the cause:
Right-click My Computer, and then click Properties. On the Advanced tab, click Settings under Startup and Recovery.
Click to clear the Automatically restart check box under System failure, and then click OK. The error message on a blue screen should remain on the screen so you can record the error information.
Instantly Reboot Upon a System Fault
Start/Run/Regedit. Navigate to...
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl
In the right pane choose AutoReboot/Right Click/Modify. Change value to 0 to disable and 1 to enable.
Windows Hangs While Saving Your Settings
When you shut down your computer, Microsoft Windows XP may stop responding (hang) while the following message is displayed: Saving your settings. When this occurs, you may be able to move the mouse pointer, but when you press CTRL+ALT+DEL, nothing happens. This issue may occur only occasionally. Supported Fix: "Restarting Windows XP".
Modify Hung App Time
Start/Run/Regedit. Navigate to...
HKEY_CURRENT_USER\Control Panel\Desktop
In the right pane, choose HungAppTimeout/Right Click/Modify/Change Value/Exit/Reboot.
Force Program Exit
Start/Run/Regedit
HKEY_CURRENT_USER\Control Panel\Desktop In the right pane find, "AutoEndTasks" (Create if not present). Set the Value of 0 or delete it. No reboot needed.
Disable Error Reporting
Start/Settings/Control Panel/System/Advanced/Error Reporting/Disable.
Windows Boots without Warning!
By default when WinXP encounters a system failure, it reboots without warning. The setting that controls this can be changed:
Control Panel/System/Advanced/Settings (Startup & Recovery)/System Failure/Uncheck-Automatically Restart. To view the event log: Administrative Tools/Event Viewer or Start/Run/eventvwr.To bypass the BSOD altogether and enable the instant "Auto Reboot" feature: Start/Run/Regedit
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl. Right click on "AutoReboot", modify and change the value to 1. Exit, reboot. To disable set the value back to 0.
Windows® Online Crash Analysis
If you experience a blue screen crash event, or Stop error, while using Microsoft Windows XP, you can upload the error report for analysis. http://oca.microsoft.com/welcome.asp
By default when WinXP encounters a system failure, it reboots without warning. The setting that controls this can be changed:
Control Panel/System/Advanced/Settings (Startup & Recovery)/System Failure/Uncheck-Automatically Restart. To view the event log: Admistrative Tools/Event Viewer or Start/Run/eventvwr.
To bypass the BSOD altogether and enable the instant "Auto Reboot" feature, run Regedit and go to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl
Right click on "AutoReboot", modify and change the value to 1. Exit, reboot. To disable set the value back to 0.
Windows® Online Crash Analysis
If you experience a blue screen crash event, or Stop error, while using Microsoft Windows XP, you can upload the error report for analysis. http://oca.microsoft.com/welcome.asp
Force Exit
Start/Run/Regedit
HKEY_CURRENT_USER\Control Panel\Desktop
In the right pane find, "AutoEndTasks" (Create if not present). Set the Value of 0 or delete it. No reboot needed.
The Computer Continuously Restarts
When you start your computer, the Microsoft Windows XP start up screen appears, and then the computer restarts. The Windows XP logon screen does not appear. This error can occur if the Kernel32.dll file is missing or damaged.
To resolve this issue, use the Windows Recovery Console to extract a new copy of the Kernel32.dll file from the original Windows XP compact disc (CD). To do this, follow these steps:
1. Start the Recovery Console. If you do not have the Recovery Console installed, start it from the Windows XP compact disc (CD). To do this, follow these steps:
a. Insert the Windows XP CD and restart the computer. If prompted, select any options required to boot from the CD.
b. When the text-based part of Setup begins, follow the prompts; choose the repair or recover option by pressing R.
c. If you have a dual-boot or multiple-boot system, choose the installation that you need to access from the recovery console.
d. When prompted, type the Administrator password.
2. At the command prompt, type "cd system32" (without the quotation marks), and then press ENTER.
3. Type "ren kernel32.dll kernel32.old" (without the quotation marks), and then press ENTER.
4. Type "map" (without the quotation marks), and then press ENTER.
5. Note the drive letter assigned to the CD-ROM drive that contains the Windows XP CD. It is displayed in a format similar to the following: D: \Device\CdRom0
6. Type "expand
Expand d:\i386\kernel32.dl_
Note the underscore character after the "L" in Kernel32.dl_
The following message appears: Kernel32.dll, 1 file(s) expanded.
7. Type "exit" (without the quotation marks). The computer restarts.
8. Remove the Windows XP CD and start the computer normally.
How to Install the Windows Recovery Console
Disable Error Checking at Startup
Start/Run/Regedit. In the right pane, delete this entry: BootExecute autocheck autochk*
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
Disable/Remove Serious Error Message Upon Boot
Start/Control Panel/System/Advanced/Performance/Settings/Advanced/Virtual Memory/Change/Set to 0. Reboot/Reset Pagefile to System Managed Size.
Disable Windows XP's Windows Tour Prompt for all Users
Start/Run/Regedit. Navigate to...
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Applets
In the right pane, locate Tour (if it doesn't exist, add it. Edit/New/Key. Then select New Value and set it to 0).
To set the same option for users, navigate to...and repeat the above steps.
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Applets
Disable Unnecessary Programs at Startup
Start/Run/Regedit. Right Click/Delete unnecessary programs listed here:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Runonce HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Disable or Enable Boot Defrag
Start/Run/Regedit. Navigate to...
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Dfrg\BootOptimizeFunction
Select Enable in the right pane/Right Click/Modify/Change Value to Y to enable, N to disable. Exit/Reboot.
Tuesday, September 19, 2006
Baidu Job
http://www.baidu.com/s?tn=baiduadv&ie=gb2312&bs=site%3A%28edu.cn%29+%C8%CB%B2%C5+%D2%FD%BD%F8+%D5%D0%C6%B8+%BD%CC%CA%A6+%B2%C4%C1%CF%D1%A7+%B8%DF%B7%D6%D7%D3+%B8%B4%BA%CF%B2%C4%C1%CF&sr=&z=0+125+2354+2493+2809+3372+4811+5161+5495+6425+6692+9337+9436&rn=100&lm=0&cl=3&f=8&wd=site%3A%28edu.cn%29+%B8%DA%CE%BB+%C8%CB%B2%C5+%D2%FD%BD%F8+%D5%D0%C6%B8+%BD%CC%CA%A6+%B2%C4%C1%CF%D1%A7+%B8%DF%B7%D6%D7%D3+%B8%B4%BA%CF%B2%C4%C1%CF&ct=0
Google job
http://www.google.com/search?num=100&hl=en&lr=&newwindow=1&as_qdr=m3&q=applicant+%2Bcurriculum+postdoc+%2Bpolymer+composite+material+%2Bsalary+bio+nano+-filetype%3Apdf+-filetype%3Adoc+-filetype%3Axls+-%22US+citizen%22&as_qdr=m3&btnG=Search
Biomaterials Post-doctoral Position-Northwestern
Biomaterials Post-doctoral Position
The Biomedical Engineering Department is offering a post-doctoral position in the area of biomaterials. The project will focus on the characterization, design and development of novel biomaterials and composites as applied to orthopedic and vascular tissue engineering. The position is available immediately and applications will be accepted until the position is filled. Salary will be commensurate with experience. Applicants should have a PhD or equivalent degree and significant experience with standard cell culture techniques/assays and relevant polymer chemistry. Send letter of interest, curriculum vitae, and the names of three references to: Dr. Guillermo A. Ameer, Northwestern University, Biomedical Engineering Department, 2145 Sheridan Rd. E310, Evanston IL 60208-3107. Email: g-ameer@northwestern.edu (Subject Line: Biomaterials Post-Doc) Telephone: 847-467-6719 FAX: 847 491-4928. Northwestern University is an Affirmative Action/Equal Opportunity Employer
The Biomedical Engineering Department is offering a post-doctoral position in the area of biomaterials. The project will focus on the characterization, design and development of novel biomaterials and composites as applied to orthopedic and vascular tissue engineering. The position is available immediately and applications will be accepted until the position is filled. Salary will be commensurate with experience. Applicants should have a PhD or equivalent degree and significant experience with standard cell culture techniques/assays and relevant polymer chemistry. Send letter of interest, curriculum vitae, and the names of three references to: Dr. Guillermo A. Ameer, Northwestern University, Biomedical Engineering Department, 2145 Sheridan Rd. E310, Evanston IL 60208-3107. Email: g-ameer@northwestern.edu (Subject Line: Biomaterials Post-Doc) Telephone: 847-467-6719 FAX: 847 491-4928. Northwestern University is an Affirmative Action/Equal Opportunity Employer
Job application link collection
http://kepu.itsc.cuhk.edu.hk/gb/beyond/astronomy/organizations/astroweb/jobs.html
ZHANG JUN' Academic Web Site (many links for job applications)
http://www.ee.cityu.edu.hk/~jzhang/phd.htm
Monday, September 18, 2006
开设材料类高分子材料与工程专业的院校名单
http://www.eol.cn/article/20020605/3057886.shtml
开设材料类高分子材料与工程专业的院校名单
[北京] 清华大学、北京理工大学、北京航空航天大学、北京化工大学、北京服装学院、北京石油化工学院、北京工商大学
[天津] 天津大学、天津轻工业学院
[河北] 河北工业大学、河北科技大学
[山西] 太原理工大学、华北工学院
[辽宁] 大连轻工业学院、沈阳化工学院
[吉林] 吉林大学、吉林工学院
[黑龙江] 哈尔滨工业大学、哈尔滨理工大学、黑龙江大学、齐齐哈尔大学、东北林业大学
[上海] 复旦大学、华东理工大学、东华大学、上海大学
[江苏] 江苏理工大学、南京理工大学、江南大学、扬州大学、南京工业大学、江苏石油化工学院
[浙江] 浙江大学、浙江工业大学
[安徽] 中国科学技术大学、合肥工业大学、安徽大学、安徽建筑工业学院
[江西] 南昌大学
[山东] 山东工业大学、青岛大学、青岛化工学院、济南大学、烟台大学
[河南] 郑州大学、郑州工业大学、洛阳工学院、郑州轻工业学院
[湖北] 湖北大学、武汉理工大学、湖北工学院、武汉化工学院、武汉科技学院
[湖南] 中南林学院
[广东] 华南理工大学、广东工业大学
[广西] 桂林工学院
[海南] 华南热带农业大学
[四川] 四川大学
[陕西] 西北工业大学
[新疆] 新疆大学
开设材料类高分子材料与工程专业的院校名单
[北京] 清华大学、北京理工大学、北京航空航天大学、北京化工大学、北京服装学院、北京石油化工学院、北京工商大学
[天津] 天津大学、天津轻工业学院
[河北] 河北工业大学、河北科技大学
[山西] 太原理工大学、华北工学院
[辽宁] 大连轻工业学院、沈阳化工学院
[吉林] 吉林大学、吉林工学院
[黑龙江] 哈尔滨工业大学、哈尔滨理工大学、黑龙江大学、齐齐哈尔大学、东北林业大学
[上海] 复旦大学、华东理工大学、东华大学、上海大学
[江苏] 江苏理工大学、南京理工大学、江南大学、扬州大学、南京工业大学、江苏石油化工学院
[浙江] 浙江大学、浙江工业大学
[安徽] 中国科学技术大学、合肥工业大学、安徽大学、安徽建筑工业学院
[江西] 南昌大学
[山东] 山东工业大学、青岛大学、青岛化工学院、济南大学、烟台大学
[河南] 郑州大学、郑州工业大学、洛阳工学院、郑州轻工业学院
[湖北] 湖北大学、武汉理工大学、湖北工学院、武汉化工学院、武汉科技学院
[湖南] 中南林学院
[广东] 华南理工大学、广东工业大学
[广西] 桂林工学院
[海南] 华南热带农业大学
[四川] 四川大学
[陕西] 西北工业大学
[新疆] 新疆大学
Rank of Chemical Engineering Departments in China-2003
化学工程与技术
天津大学
清华大学
华东理工大学
浙江大学
大连理工大学
北京化工大学
中国科学院大连化学物理研究所
华南理工大学
南京工业大学
北京理工大学
天津大学
清华大学
华东理工大学
浙江大学
大连理工大学
北京化工大学
中国科学院大连化学物理研究所
华南理工大学
南京工业大学
北京理工大学
Rank of Materials Science and Engineering Departments in China-2003
材料科学与工程
上海交通大学
中国科学院金属研究所
北京科技大学
清华大学
哈尔滨工业大学
中南大学
浙江大学
北京航空航天大学
西北工业大学
中国科学技术大学
http://kaoyan.eol.cn/article/20041010/3117480.shtml
上海交通大学
中国科学院金属研究所
北京科技大学
清华大学
哈尔滨工业大学
中南大学
浙江大学
北京航空航天大学
西北工业大学
中国科学技术大学
http://kaoyan.eol.cn/article/20041010/3117480.shtml
嫁给理工男生的十八大好处
1、理工男生不修边幅，所以家里不用太整齐；
2、理工男生很难有女朋友，会对目前这个死心塌地；
3、理工男生呆板无趣，所以不必特别花心思去取悦他；
4、理工男生很会修东西，所以不高兴时可以摔东西；
5、理工男生IQ都不低，生的儿女智商也不会差，将来读书了可以跟邻居炫耀儿女的成绩；
6、理工男生很难有时间待在家，所以嫁给他之后你还是很自由；
7、理工男生口才绝对没你好，你可以任意地跟他吵，凌辱他致死；
8、理工男生最讲理，只要你跟他不讲理，他对你一点办法都没有；
9、理工男生不知道青菜多少钱一斤，但是能很快地算出多少年的购房贷款最合算；
10、理工男生居室可能很简陋，但至少有一张看起来很大很舒服的床；
11、理工男生可以不看书，但一定要打游戏。
12、理工男生不在公共场合谈论文学青年狂热的黄色话题。
13、理工男生天空有飞鸟飞过，但是没有痕迹，爱过就是爱过了，绝不再提起，干脆利索。
14、理工男生找他们的最好方式——E-mail、MSN、QQ。
15、理工男生拒绝陌生人，拒绝圈子，他们的圈子可能从读大学的时候就开始固定。
16、理工男生喜欢小动物和小孩。
17、理工男生是天生的手工业爱好者，大到电脑，小到灯泡，一律自己动手。
18、理工男生都是环保主义、简约主义，要享受，但决不浪费。
2、理工男生很难有女朋友，会对目前这个死心塌地；
3、理工男生呆板无趣，所以不必特别花心思去取悦他；
4、理工男生很会修东西，所以不高兴时可以摔东西；
5、理工男生IQ都不低，生的儿女智商也不会差，将来读书了可以跟邻居炫耀儿女的成绩；
6、理工男生很难有时间待在家，所以嫁给他之后你还是很自由；
7、理工男生口才绝对没你好，你可以任意地跟他吵，凌辱他致死；
8、理工男生最讲理，只要你跟他不讲理，他对你一点办法都没有；
9、理工男生不知道青菜多少钱一斤，但是能很快地算出多少年的购房贷款最合算；
10、理工男生居室可能很简陋，但至少有一张看起来很大很舒服的床；
11、理工男生可以不看书，但一定要打游戏。
12、理工男生不在公共场合谈论文学青年狂热的黄色话题。
13、理工男生天空有飞鸟飞过，但是没有痕迹，爱过就是爱过了，绝不再提起，干脆利索。
14、理工男生找他们的最好方式——E-mail、MSN、QQ。
15、理工男生拒绝陌生人，拒绝圈子，他们的圈子可能从读大学的时候就开始固定。
16、理工男生喜欢小动物和小孩。
17、理工男生是天生的手工业爱好者，大到电脑，小到灯泡，一律自己动手。
18、理工男生都是环保主义、简约主义，要享受，但决不浪费。
Publication List-Tong Z-WOS
Record 1 of 70
Author(s): Wu, SZ; Wu, YF; Zeng, F; Tong, Z; Zhao, JQ
Title: Tunability of fluorescence property of a terbium-complex-containing polymer via incorporation of a transition-metal complex
Source: MACROMOLECULAR RAPID COMMUNICATIONS, 27 (12): 937-942 JUN 24 2006
Abstract: In this study, a terbium-complex monomer and transition-metal-complex monomers (Fe-III, Mn-II, and Ni-II complex monomers) are synthesized, and novel acrylate copolymers are then obtained through covalent attachment of the terbium complex and the transition-metal complex onto the macromolecular chain simultaneously. The copolymers developed herein present the characteristic fluorescence properties of the terbium(III) ion. The incorporation of an MnII complex into a Tb-III-containing polymer leads to greater fluorescence enhancement compared with the NiII complex, while the incorporation of the FeIII complex results in fluorescence quenching, thus the incorporation of different transition-metal complexes into the copolymers ensures tunability of the copolymer's fluorescence property.
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Record 2 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z; Ren, B; Zeng, F
Title: New loading process and release properties of insulin from polysaccharide microcapsules fabricated through layer-by-layer assembly
Source: JOURNAL OF CONTROLLED RELEASE, 112 (1): 79-87 MAY 1 2006
Abstract: Polysaccharide multilayer rnicrocapsules were fabricated in aqueous media by the layer-by-layer self-assembly of chitosan (CHI) and sodium alginate (ALG) on melamine formaldehyde (MF) microparticles of 2.1 mu m diameter as templates, followed by removal of the templates through dissolving at low pH. The loading process was observed with the confocal laser scattering rnicroscope (CLSM) using fluorescence labeled insulin. Insulin was spontaneously loaded into the ALG/CHI microcapsules at pH below its isoelectric point of 5.5 where insulin was positively charged and the loading capacity increased with pH decreasing from 4.0 to 1.0. Because there exited a negatively charged complex of ALG/MF residues inside the microcapsules formed during the MF particle dissolution. A novel two-temperature loading procedure was proposed as loading at 20 degrees C for the first hour and at a higher loading temperature for the second hour. This procedure was very significant that increasing the second loading temperature from 20 to 60 degrees C not only increased the insulin loading capacity, but also slowed down its release rate. The release rate of insulin at pH 7.4 was found much faster than that at pH 1.4 due to the positive charges on the insulin. Cross-linking the ALG in the microcapsule shell with calcium ions (Ca2+) or re-sealing the microcapsules with additional layers also remarkably decreased the insulin release rate. The results provide a simple method to control the loading and release of protein molecules within these polysaccharide microcapsules. (c) 2006 Elsevier B.V. All rights reserved.
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Record 3 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Tong, Z
Title: Formation of microscopic ordering and macroscopic patterns in solid polyacrylate-tetraoctylammonium bromide films
Source: MACROMOLECULES, 39 (7): 2606-2613 APR 4 2006
Abstract: Previously, we observed the rather unusual macroscopic patterns that formed in the solid films cast from organic solutions containing a surfactant tetraoctylammonium bromide (TOAB) and a chromophorecontaining polymer, and we proposed that the patterns resulted from the phase separation between the polymer-rich amorphous structures and the surfactant-rich mesomorphous structures (Macromolecules 2005, 38, 9266). In this study, it was found that the mesomorphous structure and macroscopic patterns could also form in the solid films cast from a mixture of toluene, TOAB, and polyacrylates with common polar groups like hydroxyl or carboxyl. It was also found that the higher polymer chain mobility as well as the balanced interactions between the three components in the system are crucial to the formation of mesomorphous structure and the macroscopic patterns. The patterns and the ordered mesomorphous structures were found to be destroyed at the elevated temperatures, further proving that the pattern formation needs the participation of solvent. The small-angle X-ray scattering (SAXS) investigations shows that different polar groups in the polymer chains cannot make any difference in SAXS profile in terms of peak position ratios, suggesting that the resultant mesomorphous structures do not change with the type of the polar groups in the polymer chains. These results prove that the ordered supramolecular structures can also be formed in the polymer-surfactant-organic solvent system, and the weak van der Waals interactions can lead to the formation of mesomorphous structures and macroscopic patterns.
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Record 4 of 70
Author(s): Zhao, DL; Ren, BY; Liu, SS; Liu, XX; Tong, Z
Title: A novel photoreversible poly(ferrocenylsilane) with coumarin side group: synthesis, characterization, and electrochemical activities
Source: CHEMICAL COMMUNICATIONS, (7): 779-781 FEB 21 2006
Abstract: A novel poly(ferrocenylsflane) with a coumarin side group was synthesized. This photoreversible polymer exhibits interesting electrochemical activities, which change with photodimerization and photoscission reactions of the coumarin moieties.
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Record 5 of 70
Author(s): Wang, CY; He, CY; Tong, Z; Liu, XX; Ren, BY; Zeng, F
Title: Combination of adsorption by porous CaCO3 microparticles and encapsulation by polyelectrolyte multilayer films for sustained drug delivery
Source: INTERNATIONAL JOURNAL OF PHARMACEUTICS, 308 (1-2): 160-167 FEB 3 2006
Abstract: Combination of adsorption by porous CaCO3 microparticles and encapsulation by polyelectrolyte multilayers via the layer-by-layer (LbL) self-assembly was proposed for sustained drug release. Firstly, porous calcium carbonate microparticles with an average diameter of 5 mu m were prepared for loading a model drug, ibuprofen (IBU). Adsorption of IBU into the pores was characterized by ultraviolet (UV), infrared (IR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) experiment and X-ray diffraction (XRD). The adsorbed IBU amount Gamma was 45.1 mg/g for one-time adsorption and increased with increasing adsorption times. Finally, multilayer films of prolamine sulfate (PRO) and sodium poly(styrene sulfonate) (PSS) were formed on the IBU-loaded CaCO3 n-ftroparticles by the layer-by-layer self-assembly. Amorphous IBU loaded in the pores of the CaCO3 microparticles had a rapider release in the gastric fluid and a slower release in the intestinal fluid, compared with the bare IBU crystals. Polyelectrolyte multilayers assembled on the drug-loaded particles by the LbL reduced the release rate in both fluids. In this work, polymer/inorganic hybrid core-shell microcapsules were fabricated for controlled release of poorly water-soluble drugs. The porous inorganic particles are useful to load drugs in amorphous state and the polyelectrolyte multilayer films coated on the particle assuage the initial burst release. (c) 2005 Elsevier B.V. All rights reserved.
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Record 6 of 70
Author(s): Liu, SS; Wang, CY; Liu, XX; Tong, Z; Ren, BY; Zeng, F
Title: NRET from naphthalene labels in multilayer shell wall on melamine formaldehyde microparticles fabricated with layer-by-layer self-assembly to pyrene-labeled polyelectrolyte in solution
Source: EUROPEAN POLYMER JOURNAL, 42 (1): 161-166 JAN 2006
Abstract: Core-shell colloidal particles were prepared with the core of monodisperse melamine formaldehyde particles (MF) with a diameter of 3.5 mu m. The shell deposited on the core by the layer-by-layer (LbL) self-assembly was made with a copolymer ANp3 of 2-acrylamido-2-methylpropanesulfonate sodium (AMPS) and 3 mol% naphthalene label monomer and poly(diallyldimethylammonium chloride) (PD). Nonradiative energy transfer (NRET) from the naphthalene labels deposited on the MF particles to pyrene labels at a polyelectrolyte APy3, a copolymer of AMPS and 3 mol% pyrene label monomer, or to an ionic pyrene probe 1-pyrenemethylamine hydrochloride (PyMeA (.) HCl) in water was observed. The NRET efficiency was expressed as the emission intensity ratio I/I-0 of naphthalene with and without existence of pyrene in the surrounding solution. With increasing pyrene concentration, I/I-0 decreased down to about 0.2 and the mechanism for this NRET from the inner naphthalene label to the pyrene labels in solution is still ambiguous. (c) 2005 Elsevier Ltd. All rights reserved.
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Record 7 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Luo, SJ; Ren, BY; Tong, Z
Title: Mesomorphous structure and macroscopic patterns formed by polymer and surfactant from organic solutions
Source: MACROMOLECULES, 38 (22): 9266-9274 NOV 1 2005
Abstract: Ordered mesomorphous structures were obtained from the ternary system of organic solvent, polymer, and surfactant, and this microscopic ordering could lead to unique water-wave-like macroscopic patterns in solid polymer-surfactant film. The mesomorphous structures and macroscopic patterns were obtained by dissolving a nonpolyelectrolyte polymer and cationic surfactant in organic solvents and casting the solutions on glass substrates. The patterns thus obtained are composed of concentric rings, and these concentric rings, with their diameters up to centimeters, alternatively consist of macroscopic convex ridges and concave valleys, with the former being amphormous phase and the latter being ordered mesomorphous one. This macroscopic patterning in a solid polymer-surfactant system could offer a new way for fabricating ordered supramolecular structure in macroscopic dimensions.
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Record 8 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z
Title: Deposition temperature effect on release rate of indomethacin microcrystals from microcapsules of layer-by-layer assembled chitosan and alginate multilayer films
Source: JOURNAL OF CONTROLLED RELEASE, 106 (3): 319-328 SEP 2 2005
Abstract: Indomethacin (IDM) microcrystals sized 5 similar to 10 mu m were directly encapsulated with nature polysaccharides chitosan (CHI) and sodium alginate (ALG) through layer-by-layer (LbL) self-assembly. Due to partial dissolution of IDM in the deposition solution, the retention of the IDM microcrystals gradually decreased with increasing deposition times and became 47.7% as 10 layers of polysaccharides formed. The release rate of the IDM from the microcapsules was monitored with UV absorbance. The half release time t(1/2) of IDM in the microcapsule increased with the layer number and the initial burst phenomenon was relieved after encapsulation. It was found that added NaCl did not affect the release rate even up to 0.5 M of its concentration, while increasing the release temperature remarkably speeded up the release process. The prolonged release of the encapsulated IDM was still observed when the aqueous release solution containing 20 vol.% ethanol. It was very significant that increasing deposition temperature from 20 to 60 degrees C reduced the release rate efficiently, owing to the increase in multilayer thickness and formation of a more perfect multilayer film. This finding provides a new and simple method to control the permeability of the LbL assembled multilayer films. Because of the biodegradability of CHI and ALG and various methods to tune the release rate, the LbL self-assembly on drug microcrystals promises high potential for encapsulation used in controlled release. (c) 2005 Elsevier B.V. All rights reserved.
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Record 9 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z
Title: Multilayer nanocapsules of polysaccharide chitosan and alginate through layer-by-layer assembly directly on PS nanoparticles for release
Source: JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION, 16 (7): 909-923 2005
Abstract: Polysaccharide multilayer nanocapsules have been fabricated in aqueous media by the layer-by-layer self-assembly of chitosan (CHI) and sodium alginate (ALG) on monodisperse polystyrene (PS) nanoparticles with a diameter of 180 nm as template, followed by removal of the templates through dissolving in THE The pH and added salt concentration of the polyelectrolyte deposition solutions were optimized to ensure the alternating deposition. Consequently, the most suitable pH values were found to be 6.0-8.0 for ALG and 3.5 for CHI and were used in the deposition. The concentration of added NaCl used in the adsorption solutions was 0.5 M, which led to an average thickness of about 13 nm for 5 bilayers of CHI/ALG shell-wall zeta-potential indicated the stepwise and alternating adsorption of CHI and ALG to form multilayer film on the PS nanoparticles. The characteristic bands of PS residue almost disappeared in the IR spectrum of the nanocapsule after dipped in THF, confirming thorough removal of PS templates from the core-shell particles. TEM, SEM and AFM were utilized to observe the nanocapsules of about 225 nm in diameter (by TEM). A hydrophilic drug model, acridine hydrochloride (AH), was chosen to investigate the loading and release properties of the nanocapsules. The positively charged AH spontaneously deposited into the capsule due to the electrostatic interaction with the negatively charged styrene sulfonate residues from the PS template inside the capsule. The rate of AH release became slightly slower when the capsule wall was cross-linked with glutaraldehyde, but the accumulative released amount for the crosslinked capsule was obviously reduced. These nanocapsules made from nature polysaccharides have a potential application in controlled drug release.
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Record 10 of 70
Author(s): Lu, L; Liu, XX; Dai, L; Tong, Z
Title: Difference in concentration dependence of relaxation critical exponent n for alginate solutions at sol-gel transition induced by calcium cations
Source: BIOMACROMOLECULES, 6 (4): 2150-2156 JUL-AUG 2005
Abstract: The sol-gel transition in aqueous alginate solutions induced by chelation with calcium cations from in situ release has been investigated with viscoelastic methods. Two alginate samples having different molecular weights (MW) were used over the concentration C-Alg of 2 similar to 6 wt % with different mole ratio f of Ca2+ to the alginate repeat unit. The gel pointf(gel) and relaxation critical exponent n were determined according to Winter's criterion, the later agrees well with that obtained from the relaxation modulus. The results indicate that the power law is valid for the dynamic relaxation at the gel point and the critical gel possesses the self-similarity in structure. With increasing C-Alg, f(gel) for the alginate with lower MW decreases dramatically and n is almost constant of about 0.71. In contrast, f(gel) for the higher MW alginate with is almost a constant and n decreases from 0.72 then levels off at 0.37 with increasing C-Alg, indicating that the concentration dependence of n varies with MW of alginate in the starting solution. The fractal dimension d(f) estimated from n suggests a denser structure in the critical gel of higher MW alginate. Either n or df has been found to follow one curve for the two samples if plotted against the number of cross-link junctions per polymer chain, which is proportional to the alginate MW.
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Record 11 of 70
Author(s): Ren, BY; Cheng, ZY; Tong, Z; Liu, XX; Wang, CY; Zeng, F
Title: Novel structure change in nonequimolar complexes of linear poly(ethylenimine) and octadecanoic acid: Effects of composition
Source: MACROMOLECULES, 38 (13): 5675-5680 JUN 28 2005
Abstract: Polymer-amphiphile complexes based on specific noncovalent interactions have received considerable attention in recent years due to its simple preparation and interesting properties. However, little attention has been paid to the complex composition effect on the crystal and mesomorphous structure of amphiphile side chains in nonequimolar polymer-amphiphile complexes. The structure of a series of nonequimolar linear poly(ethylenimine)-octadecanoic acid complexes, lPEI-OA-x, with the molar ratio x of OA to the lPEI amino group ranging from 0.66 to 1.45, was investigated with WAXD, SAXS, FTIR, DSC, fluorescence spectrum, and polarized optical microscope. Two crystalline modifications beta(O) (beta-orthorhombic) and beta(T) (beta-triclinic) of OA side chains have been found to coexist in the complexes varying with x, and only 8-10 CH2 groups in an OA molecule participate in the crystallization. The crystalline OA tails with amorphous lPEI form the lamella stacking structure. The complexes of x > 1.0 are predominant with beta(O) form and stacked into an end-to-end bilayer lamella with the long period of similar to 5.6 nm. While for the complexes of x < 1.0, the PT form is dominantly stacked in the interdigitating monolayer structure with the long period of similar to 2.8 nm. The fluorescence emission from pyrene-doped complexes indicates a decrease in the microenvironment polarity with increasing x. The thermotropic liquid crystal state has been observed from the complexes of x < 1.0 at temperatures above the melting point of the OA tail crystal. This study demonstrates that the crystalline and mesomorphous structures of polyelectrolyte-amphiphile complexes can be effectively tuned by changing the relative amount of bound amphiphiles. In other words, the stacking structure of amphiphile molecules depends on the amount of added binding polyelectrolytes.
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Record 12 of 70
Author(s): Sun, QL; Tong, Z; Wang, CY; Ren, BY; Liu, XX; Zeng, F
Title: Charge density threshold for LbL self-assembly and small molecule diffusion in polyelectrolyte multilayer films
Source: POLYMER, 46 (13): 4958-4966 JUN 17 2005
Abstract: Polyelectrolyte multilayer films were prepared via the layer-by-layer self-assembly using poly(diallydimethylammonium chloride) (PDADMAC) and pyrene labeled polyanions of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N,N-dimethylacrylamide copolymers with different charge densities (AMPS mole fraction) F-AMPS = 0.20-0.999. Multilayer growth with alternating deposition from salt-free polyelectrolyte solutions was monitored by fluorescence intensity and film thickness, showing a charge density threshold between 0.574 and 0.711 for our polyanions, below which the multilayer cannot be formed due to desorption in the following depositions. For the fully charged polyanion, thickness of the multilayer film increased with increasing NaCl concentration in the deposition solution; while for other polyanions with lower F-AMPS, little growth in multilayer films was found when NaCl concentration was 0.02 mol/L or higher. The quenching rate of nitromethane to the pyrene label in the multilayer film was adopted to detect the chain density and permeability of these films. Decreasing the charge density, increasing the salt concentration and reducing the layer number will accelerate the quenching rate. The former two is due to the formation of a looser structure in the multilayer films at low charge density of the polyelectrolytes or high salt concentration in the deposition solutions, while the last one is mainly due to the reduction of diffusion distance. (c) 2005 Elsevier Ltd. All rights reserved.
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Record 13 of 70
Author(s): Liang, ZP; Wang, CY; Tong, Z; Ye, WH; Ye, SQ
Title: Bio-catalytic nanoparticles in multilayer assembled throt with urease immobilized gh layer-by-layer technique
Source: REACTIVE & FUNCTIONAL POLYMERS, 63 (1): 85-94 2005
Abstract: A novel core-shell colloid with multilayer for biocatalysis was elaborated by the layer-by-layer assembly technique. Urease was adsorbed in alternation with the oppositely charged polyelectrolytes onto polystyrene (PS) colloid nanoparticles as either polycation or polyanion switched by the solution pH. Microclectrophoresis, transmission electron microscopy (TEM) and UV-vis spectrum absorbance were employed to monitor the regular and stepwise growth of the multilayer films with the enzyme and counterpart polyclectrolytes. The colloid nanoparticles coated with negatively charged urease were found to be more stable than those coated with positively charged urease. The catalytic activity of the urease immobilized on the PS nanoparticles, having higher storage stability, was 23.67% of that for the free urease in aqueous solution. Addition of 0.05 M NaCl increased the activity of the immobilized urease by 65%. Coverage of synthetic polyelectrolyte layers on the urease layer reduced the activity of the immobilized urease. Therefore, by adding salts or covering with polyclectrolytes, we have achieved an enhancement or restraint of the bioactivity of immobilized enzyme, indicating a novel method for biotechnology. (c) 2005 Elsevier B.V. All rights reserved.
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Record 14 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Tong, Z
Title: Energy and electron transfers in photosensitive chitosan
Source: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 127 (7): 2048-2049 FEB 23 2005
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Record 15 of 70
Author(s): He, CY; Liang, ZP; Wang, CY; Liu, XX; Tong, Z
Title: Immobilization of superoxide dismutase by layer-by-layer assembly on surface of PS colloid particles and their bioactivity
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 26 (1): 88-92 JAN 2005
Abstract: Novel enzyme multilayer films on the surface of polystyrene(PS) colloid particles was fabricated by layer-by-layer (LbL) self-assembly. Superoxide dismutase(SOD) was adsorbed on the PS particles as either polycation or polyanion switched by adjusting pH alternatingly with the oppositely charged polyelectrolytes. zeta-Potential and TEM results indicated the regular and stepwise growth of the multilayer structure. The amount of the immobilized SOD was estimated from the difference in SOD bioactivity of the supernatant after adsorption and SOD solution before adsorption by using the pyrogallol oxidation method. The immobilization amount of SOD was 12 and 51 IU when adsorbed in pH = 8.0 as a polyanion and in pH = 4.3 as a polycation, respectively. However, the relative activity of the former was 23.4% while that of the latter was 2.9%, compared to that of free SOD in aqueous solution. Anionic SOD was found to form more regular and smooth layers on the PS particle surface and cationic SOD to aggregate. By adjusting pH of the adsorption solution we can optimize the assembled status and bioactivity of particle-immobilized enzyme.
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Record 16 of 70
Author(s): Wang, CY; Ren, BY; Tong, Z; Zeng, F; Liu, XX; Wu, SZ; Liu, P
Title: Fluorescence observations on complex formation between linear and hyperbranched polyelectrolytes in dilute aqueous solutions
Source: EUROPEAN POLYMER JOURNAL, 41 (1): 185-191 JAN 2005
Abstract: The complexation between poly(ethylene imine) (PEI) and poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) or AMPS copolymers was investigated with the relative excimer emission intensity I-E/I-M of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA . HCl), fluorescence nonradiative energy transfer (NRET) I-Py/I-Np of naphthalene to pyrene labels, the fluorescence anisotropy r and I-E/I-M of pyrene labels. PEI was a hyperbranched weak polycation in acid solution, which formed complex with anionic polyelectrolytes due to the electrostatic attraction. The I-E/I-M of PyMeA . HCl probe decreased to zero, the intra-, intermolecular NRET I-Py/I-Np and I-E/I-M of pyrene labels on the AMPS copolymers reached their maxima when 7 was increased from 0 to 2.4, which was defined as the mole ratio of the amino group in PEI to the AMPS group in the polyanion. These facts indicated the formation of nonstoichiometric complex of the oppositely charged polyelectrolytes when chi = 2.4 at the concentration much lower than their overlap concentrations. The intermolecular aggregate appeared as indicated by an increase in the intermolecular I-Py/I-Np and r with chi up to 2.4 due to neutralizing and hydrophobizing the polyelectrolytes and the bridging effect of the PEI chain bound on different polyanion chains. At high pH, PEI became a neutral polymer and did not bind with the AMPS anion to form the complex as illustrated by the constant value of r for the pyrene labels attached to the AMPS polyanion as that without addition of PEI. The amino group in PEI quenched pyrene and naphthalene emission, resulting a decrease in both I-Np and I-Py. (C) 2004 Elsevier Ltd. All rights reserved.
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Record 17 of 70
Author(s): Tang, T; Zeng, F; Wu, SZ; Tong, Z; Luo, DB; She, WL
Title: Photo-induced birefringence and all-optical switching effect in azobenzene-grafted polyurethanes
Source: OPTICAL MATERIALS, 27 (3): 585-590 DEC 2004
Abstract: In this study, azobenzene-containing chromophore 4-N,N'-bis-(2-hydroxyethyl)amino-4'-nitro-azobenzene were synthesized by using 4-nitroaniline and m-tolyldiethanoamine. Then they were polymerized with toluene 2,4-di-isocyanate (TDI) and polyethylene glycol (PEG) in N,N'-dimethylformamide (DMF) to obtain novel polyurethanes which exhibit photo-induced birefringence properties. Polyols such as 1,4-dibutanol or tri-hydroxyl propane were introduced into the polyurethane structure to adjust the flexibility of the polymer chain segments. An experimental setup, in which the He-Ne lasers produced signal beams and Ar+ lasers the pump beams, was employed to investigate the photo-induced birefringence and optic-optic switching properties of these polyurethane materials. It is found that, with increasing pump beam power, the extent of both birefringence and optic switching response first slightly increased due to reorientation mechanism, and then decreased due to thermal effects. And the flexibility for the chain segment also has remarkable effects on birefringence extents and optic switching modulations. (C) 2004 Elsevier B.V. All rights reserved.
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Record 18 of 70
Author(s): Ren, BY; Tong, Z; Liu, XX; Wang, CY; Zeng, F
Title: Mesomorphous structure and properties of non-equimolar complexes of poly (ethylenimine) and perfluorooctanoic acid
Source: LANGMUIR, 20 (24): 10737-10743 NOV 23 2004
Abstract: A series of solid complexes, PEI-PFAO, made of poly(ethylenimine) (PEI) and perfluorooctanoic acid (PFOA) with different compositions were prepared through a "starving addition" method, where PFOA was fed into PEI solution at the molar ratio, phi(feed), of acid group to the amino group of PEI, never beyond unity. Wide-angle X-ray diffraction diagrams confirmed amorphous structure of these complexes. Small-angle X-ray scattering indicated two ordered mesomorphous structures of alpha and beta lamellar phases, with respective long periods of 2.29 and 1.15 nm in the complexes. By increasing the actual molar ratio, phi, of PFOA to the amino group of PEI, the complex structure was altered from alpha-phase dominant to beta-phase dominant. All complexes exhibited two thermal degradation processes induced by decomposition of the bound PFOA below 230 degreesC and PEI backbone at about 350 degreesC. The initiating degradation temperature, T-id, decreases with increasing phi due to the preferential degradation of the PFOA chain bound to the tertiary amino groups. The glass transition temperature, T-g, of the complex increases with phi up to the degradation of the complex of phi = 1. This increase in T-g with phi also supports an ordered alignment of the bound PFOA chains, which greatly restricts the PEI mobility. The solid surface tension, gamma(S), and critical surface tension, gamma(C), of the complex are between 15.4 and 16.8 mN/m and between 13.5 and 15.4 mN/m, respectively. The latter is very close to or even smaller than gamma(C) of PTFE (15 mN/m), suggesting the enrichment of CF2 and CF3 groups at the complex surfaces. The fact that the PEI-POFA complex combines high hydrophobicity with selective thermal degradation of bound fluorinated chains promises a potential of selective change and local functionalization of the surface in a well-controlled manner.
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Record 19 of 70
Author(s): Liang, ZP; Wang, CY; Sun, QL; Tong, Z
Title: Novel microcapsule fabricated by LbL nano self-assembly
Source: PROGRESS IN CHEMISTRY, 16 (4): 485-491 JUL 2004
Abstract: The article focuses on a novel and versatile technique of layer-by-layer deposition(LbL), developed for preparing nano- or micro- capsules. The strategy outlined readily affords precise control over the size, composition, construction, shape and wall thickness of the hollow capsules. Consequently these capsules have potential applications in biochemistry, pharmacy, controlled- release, cosmetic and catalyst.
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Record 20 of 70
Author(s): Liu, P; Zhang, YM; Feng, GJ; Hu, JH; Zhou, XP; Zhao, QH; Xu, YH; Tong, Z; Deng, WJ
Title: Synthesis and liquid crystal properties of a novel family of oligothiophene derivatives
Source: TETRAHEDRON, 60 (24): 5259-5264 JUN 7 2004
Abstract: In order to develop novel oligothiophene-based liquid crystals capable of hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N'-dialkyl-5,5"-dichloro-2,2:5',2"-terthiophene-4,4"-dicarboxamide (DNC(n)DCl3T, n=8, 18), N,N"-dialkyl-5,5"-dibromo-2,2':5',2"-terthiophene-4,4"-dicarboxamide (DNC(n)DBr3T, n=5, 8, 16, 18), or N,N'-dialkyl-5,5"-diiodo-2,2:5',2"-terthiophene-4,4"-dica-rboxamide (DNC(n)DI3T, n=8, 18), were designed and synthesized, and their thermal behaviour was examined. It was found that DNC(18)DC13T, DNC(n)DBr3T and DNC(n)DBr3T (n=8, 16, 18) form a smectic A phase and that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding also plays a role in the formation of a liquid crystal phases in the DNC(n)DBr3T system. (C) 2004 Elsevier Ltd. All rights reserved.
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Record 21 of 70
Author(s): Zeng, F; Wu, SZ; Tang, T; Sun, ZW; Wang, CY; Liu, XX; Tong, Z
Title: Preparation of colloidal crystals with polyhedral building blocks through post-polymerization
Source: COLLOID AND POLYMER SCIENCE, 282 (6): 651-655 APR 2004
Abstract: An alternative approach was adopted to prepare colloidal crystal with polyhedral building blocks. First, monodisperse polystyrene particles that contained about 30% wt of monomer were obtained by emulsifier-free emulsion polymerization at 38 degreesC. These monomer-containing particles were used to prepare colloidal crystal on the surface of dispersion, before the spherical particles in the colloidal crystals underwent deformation between two quartz plates at 75 degreesC for 40 min by interfacial tensions, and finally the deformed particles were "frozen" through post-polymerization.
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Record 22 of 70
Author(s): Tong, Z; Wang, CY; Ren, BY; Liu, XX; Zeng, F
Title: Binding of ionic surfactants on oppositely charged polyelectrolytes observed by fluorescence methods
Source: CHINESE JOURNAL OF POLYMER SCIENCE, 21 (6): 609-620 NOV 2003
Abstract: Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity I-E/I-M of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA(.)HCl) and the non-radiative energy transfer (NRET) I-Pv/INp of naphthalene to pyrene for labeled polyelectrolytes were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1 aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1 polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymer-surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.
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Record 23 of 70
Author(s): Wu, SZ; Zeng, F; Yao, SL; Tong, Z; She, WL; Luo, DB
Title: All-optical switching effect in novel chiral biazobenzene polymer films
Source: MACROMOLECULES, 36 (25): 9292-9294 DEC 16 2003
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Record 24 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Binding on strong polyelectrolytes of mixed ionic and nonionic surfactants below their critical micelle concentration observed by fluorescence
Source: COLLOID AND POLYMER SCIENCE, 282 (2): 141-148 DEC 2003
Abstract: The binding of mixed surfactants of cationic cetyltrimethylammonium bromide (CTAB) and nonionic octaethylene glycol monododecyl ether (C12E8) on anionic polyelectrolyte poly[2-acrylamido-2-methylpropanesulfonic acid (PAMPS)] and fluorophore-labeled copolymers containing about 40 mol% of AMPS was investigated at different mole fractions, Y , of CTAB in the surfactant mixture. The excimer emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA.HCl), nonradiative energy transfer (NRET) between pyrene and naphthalene labels and I-1/ I-3 of the pyrene label were determined by varying the total surfactant concentration, c(Surf). The I-E/ I-M value of PyMeA.HCl firstly increases and then decreases to 0 with c(Surf), showing a maximum on every curve. The critical aggregation concentration of the mixed surfactants determined from the I-E/ I-M maximum decreased from 5x10(-5) to 1x10(-5) mol/l as Y increased from 0.1 to 0.50, and then leveled off as Y increased up to unity. And at least 5x10(-6) mol/l CTAB was required for the mixed surfactants to bind on the PAMPS cooperatively. Equimolar binding of CTAB on AMPS was formed at I-E/ I-M=0 when Y greater than or equal to0.25, while at Y =0.1 some CTAB molecules in the mixed micelle were directed to the water phase without binding with AMPS. Both the intramolecular and the intermolecular NRET increased and then decreased with c(Surf), having a maximum on each curve corresponding to the equimolar binding of CTAB and AMPS so long as Y >0, indicating the coiling of the chain and interchain aggregation upon bound surfactants. The I-Py/ I-Np value at the maximum decreased with decreasing Y because more nonionic surfactant C12E8 participated into the polyelectrolyte-mixed surfactant complexes together with bound CTAB.
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Record 25 of 70
Author(s): Lu, L; Liu, XX; Qian, LY; Tong, Z
Title: Sol-gel transition in aqueous alginate solutions induced by cupric cations observed with viscoelasticity
Source: POLYMER JOURNAL, 35 (10): 804-809 2003
Abstract: Sol-Gel transition was occurred in 2 wt% aqueous solutions of four alginate samples with different molecular weight M-w and the ratio M/G of repeat unit mannuronate (M) to guluronate (G) induced by adding cupric ions. The transition was monitored with dynamic moduli G' and G" in the linear region of viscoelasticity and the gel point was determined according to the Winter's criterion where the loss angle tan (5 became independent of frequency omega. The mole ratio of Cu2+ to the carboxyl group in alginate at gel point, f(gel), was higher for the samples with lower molecular weight than those with higher molecular weight without obvious M/G dependence. This suggested there was no M/G selection of Cu2+ complex formation with alginate. The relaxation critical exponent n for alginate samples with higher G content was lower than 0.5, meaning G' > G" for the critical gels with a denser network. The cupric ion number relevant to one alginate chain at the gel point, N-gel, was estimated from f(gel) M-n/M-0 and reflected the gel elasticity.
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Record 26 of 70
Author(s): Sun, QL; Wang, CY; Ren, BY; Liu, XX; Zeng, F; Liu, P; Tong, Z
Title: Effects of added salts on intra- and inter-molecular fluorescence NRET of sulfonate polyelectrolytes
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 24 (9): 1695-1699 SEP 10 2003
Abstract: Naphthalene and pyrene singly and doubly labeled polyelectrolytes were prepared by radical copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) from 5% to 99% (molar fraction) and N, N-dimethylacrylamide with the label monomers. Fluorescence nonradiative energy transfer (NRET) was measured in NaCl and CaCl2 aqueous solutions up to the concentration of 6 X 10(-3) mol/L. Intra- and inter-molecular NRET determined with doubly labeled samples and mixtures of singly labeled samples indicated that owing to the salt screening effect, increasing salt concentration enhanced the NRET and the enhancement of calcium cation was stronger than that of sodium cation. The normalized NRET E-n, defined as the NRET in salt solution relative to that in water for a given sample, showed that intramolecular E-n decreased with the increase of charge density F-AMPS in the samples with a maximum at F-AMPS approximate to 0.45. In contrast, the intermolecular E-n increased with the increase of F-AMPS, suggesting that there were inhomogeneous intermolecular aggregates in polyelectrolyte solutions due to the condensed counterions even at a concentrations lower than the overlap threshold c*.
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Record 27 of 70
Author(s): Liu, XX; Qian, LY; Shu, T; Lu, L; Tong, Z
Title: Sol-gel transition and gel point determination for aqueous solutions of sodium alginate
Source: ACTA POLYMERICA SINICA, (4): 484-488 AUG 2003
Abstract: The aqueous solutions of 4 sodium alginate samples with different molecular weights, molecular weight distributions and M/G ratios were characterized with GPC, elemental analysis, and H-1-NMR. The sol-gel transition was determined by monitoring the dynamic moduli of these solutions with increasing their concentration within the linear viscoelasticity region at 25 degreesC. This transition was found to obey the Winter and Chambon's relaxation modulus equation G(t). From the independency of tandelta on frequency omega, the concentration of the gel point c(gel) and the critical exponent for the sol-gel transition n were estimated. For all samples c(gel) is 7.6wt% similar to 8.0wt%, almost independent of molecular weight M-w, and n equals 0.32 similar to 0.38 for three samples with higher M-w and 0.61 for the sample with lower M-w. This finding indicates that physical gelation in aqueous solutions of sodium alginate is mainly induced by the interaction between repeat units of the macromolecules, and that the longer chains contribute more perfect crosslinking structure at the gel point.
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Record 28 of 70
Author(s): Sun, QL; Wang, CY; Ren, BY; Tong, Z; Liu, XX; Zeng, F; Liu, P
Title: Conformation of polyelectrolyte chains with sulfonate groups observed with fluorescent nonradiative energy transfer
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 24 (7): 1302-1306 JUL 2003
Abstract: Strong polyelectrolytes were prepared by copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) from 5% to 99%(charge densities) with N,N-dimethylacrylamide and lightly labeled by naphthalene and pyrene, respectively. The overlap mass concentration p* determined by intermolecular nonradiative energy transfer(NRET) decreased from 0.55 to 0.25 g/L with increasing the charge density of the samples and was about one order of magnitude smaller than that determined from the relative excimer emission. With increasing the charge density in dilute aqueous solution, the intermolecular NRET was first weakened till the charge density of about 30% and then enhanced. This phenomenon can be qualitatively interpreted in the framework of Manning's theory for counterion. condensation and tion of highly charged polyelectrolytes.
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Record 29 of 70
Author(s): Liu, P; Zhou, XP; Hu, JH; Zhao, QZ; Deng, WJ; Tong, Z; Xu, YH; Wan, MX
Title: Synthesis and liquid crystal properties of a novel class of oligothiophene derivatives
Source: ACTA CHIMICA SINICA, 61 (5): 774-779 MAY 2003
Abstract: With the aim of developing new oligothiophene-based liquid crystals involving hydrogen bonding, new terthiophene derivative's containing an alkylamide group, N,N'-dialkyl-5,5"-dibromo-2,2': 5', 2"-terthiophene-4,4"-dicarboxamide (DNC(n)DBr3T, n = 5, 8, 16, 18), were designed and synthesized, and their thermal behaviors were examined. While DNC(n)DBr3T compounds with n 16, 18 were found to form smectic A phase, DNC(5)DBr3T did not form liquid crystal phase. In addition to liquid crystal behavior, crystal polymorphism was also observed for DNC(16)DBr3T. It is shown that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding plays a role in the formation of liquid crystal phase in the DNC(n)DBr3T system.
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Record 30 of 70
Author(s): Sun, QL; Ren, BY; Liu, XX; Zeng, F; Liu, P; Tong, Z
Title: Fluorescence study for the electrostatic interaction and aggregation in dilute polar solution of polyelectrolytes
Source: MACROMOLECULAR SYMPOSIA, 192: 251-264 MAR 2003
Abstract: Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethylacryl-amide (DMAA) were observed in dilute salt-free aqueous solutions as a function of the mole fraction F-AMPS of AMPS from 0 to 0.896. Monoexponential and biexponential decays were found for the samples of F-AMPS < 0.35 and samples of F-AMPS > 0.35, respectively. The fast decay component is 80% and the averaged lifetime and lifetime tau(1) of the fast decay decreased with increasing F-AMPS. Quenching efficiency of Cu2+, CH3NO2, and dinitrobenzene to the pyrene label was investigated in the framework of Stern-Volmer plot. The quenching effects of Cu2+ included both of dynamic and static ones, the latter was due to the condensed Cu2+. For the neutral quenchers, the quenching rate constant k(q) increased when F-AMPS < 0.449 then decreased, showing a decline of accessibility to the pyrene label. I-1/I-3 value in salt-free dilute aqueous solution and in DMSO solution decreased obviously with an increase in F-AMPS, indicating that the labeled fluorophore experienced a decrease in polarity of its microenvironment with increasing charge density of the polymer. This I-1/I-3 decrease was enhanced with increasing the polymer concentration and adding salt NaCl up to 0.75 mol/L showed no effect on the appearance of this decrease. These results were interpreted consistently with the counterion condensation concept, where condensed counterions induced the "temporal" aggregation of less-polar in the polyelectrolyte solutions surrounding the pyrene labels.
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Record 31 of 70
Author(s): Sun, QL; Tong, Z; Wang, CY; Liu, XX; Zeng, F
Title: Fluorescence decay and quenching of pyrene labeled on sulfonate polyelectrolytes in salt-free aqueous solutions
Source: EUROPEAN POLYMER JOURNAL, 39 (4): 697-703 APR 2003
Abstract: Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N, N-dimethylacrylamide were observed in dilute salt-free aqueous solutions as a function of the mole fraction F-AMPS of AMPS from 0 to 0.896. Monoexponential decay was found for the samples of FAmps < 0.35 and biexponential decay for the samples of F-AMPS > 0.35. The fast decay component is 80%, and the averaged lifetime (T) and lifetime T, of the fast decay is decreased with increasing FAmps. Quenching efficiency of Cu2+, I-, CH3NO2, and dinitrobenzene to the pyrene label was investigated in the framework of Stern-Volmer plot. With increasing FAmps the quenching efficiency of Cu2+ is increased while that of I- decreased. For the neutral quenchers, the quenching rate constant k(q) increases when F-AMPS < 0.449 then decreases, showing a decline of accessibility to the pyrene label. These results were interpreted consistently with the counterion condensation concept, where condensed counterions caused the polyelectrolyte chains to aggregate. The existence of less-polar "temporal aggregated domain" in highly charged polyelectrolytes appears to lead to the slower decay and lower accessibility of the pyrene labels. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Record 32 of 70
Author(s): Guo, YQ; Tong, Z; Chen, MC; Liang, XH
Title: Solution miscibility and phase-change behavior of a polyethylene glycol-diacetate cellulose composite
Source: JOURNAL OF APPLIED POLYMER SCIENCE, 88 (3): 652-658 APR 18 2003
Abstract: Polyethylene glycol (PEG) and diacetate cellulose (CDA) exhibit good miscibility in acetone solution. The miscibility is related to the molecular weight of PEG, which increases as miscibility decreases. The phase-change behavior of PEG in composite with CDA prepared from the miscible solution was found to be completely different from that of pure PEG. When the PEG fraction in the composites was less than 85%, PEG within the composite did not melt into liquid; even when the temperature was 40degreesC higher than the melting point of PEG, the PEG-CDA composite exhibited solid-solid phase-change behavior. Thermal analysis indicated that the PEG-CDA composite had greater enthalpy and exhibited good thermal stability. The PEG-CDA composite that exhibited solid-solid phase-change behavior can be used as a new kind of phase-change material for thermal energy storage and temperature control. (C) 2003 Wiley Periodicals, Inc.
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Record 33 of 70
Author(s): Liu, XX; Qian, LY; Shu, T; Tong, Z
Title: Rheology characterization of sol-gel transition in aqueous alginate solutions induced by calcium cations through in situ release
Source: POLYMER, 44 (2): 407-412 JAN 2003
Abstract: Four alginate gels were prepared by in situ release of calcium cations from Ca-EDTA with gradual hydrolysis Of D-glucono-delta-lactone (GDL) in 3 wt% of aqueous solutions of four alginate samples with different M/G compositions, molecular weights, and molecular weight distributions. The sol-gel transition was monitored by measuring the dynamic mechanical spectroscopy in the linear region with variation in the mole ratio f of Ca2+ to the carboxyl group in the alginate. f(gel), the critical value off at the gel point, was determined according to the appearance of power law relaxation for the storage and loss moduli as proposed by Winter and Chambon. The critical exponent of relaxation moduli n for the power law was estimated from the loss tangent tan delta = G(II)/G(I) at the gel point which is independent of angular frequency. f(gel) for the two samples with higher M/G ratio is about 0.037 while that for the other two samples with lower M/G ratio is 0.049 and 0.060, suggesting that more Ca2+ cations are chelated into the 'egg-box' cavities formed by the G sequence to cross-link alginate chains with higher G content. The n value is higher than 0.5, showing that the Ca2+ induced alginate network is not perfect due to its low concentration. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Record 34 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Simulation for binding equilibrium of ionic derivative of pyrene with polyelectrolyte
Source: ACTA POLYMERICA SINICA, (6): 729-733 DEC 2002
Abstract: Binding of cationic derivative of pyrene, pyrenemethylamine hydrochloride (PyMeA.HCl) to a polyanion, poly (2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in aqueous solutions was probed by the excimer fluorescence and simulated with a competitive binding equilibrium model. The relative emission intensity I-E/I-M of excimer to monomer displays a maximum with increasing PyMeA.HCl concentration and the binding stoichiometry for saturation binding is determined from the concentrations of PAMPS and PyMeA.HCl at the maximum. I-E/I-M obviously decreases with adding sodium chloride of about 10(-4) mol/L into the solution due to the. competitive binding of sodium and probe cations. In our binding equilibrium model; the binding of different cations on anionic polymer is considered as an equilibrated reversible process governed by the equilibrium constant. I-E and I-M are assumed to be proportional to the probe concentrations forming excimer and remaining individually, respectively. Calculated bound probe concentration c(DL) increases with total probe concentration c(DO) before binding saturation and the increasing rate becomes higher with higher value of the equilibrium constant. The simulated I-E/I-M as the above probe concentration ratio, also shows a maximum with increasing c(DO) at the same position as experimentally observed. By assuming. a comparable binding equilibrium constant for the cation of added salt, the, abrupt decrease in I-E/I-M observed with adding salt is reproduced by the simulation.. These results, indicate that the competitive binding of ionic pyrene probe on polyelectrolyte can be reasonably described by the binding equilibrium model.
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Record 35 of 70
Author(s): Zeng, F; Sun, ZW; Wang, CY; Ren, BY; Liu, XX; Tong, Z
Title: Fabrication of inverse opal via ordered highly charged colloidal spheres
Source: LANGMUIR, 18 (24): 9116-9120 NOV 26 2002
Abstract: A new and simple procedure for producing highly ordered three-dimensional colloidal crystalline template was developed, which employs latexes containing highly charged polystyrene spheres. The water on the surface of the latex was evaporated, causing the formation of close-packed colloidal crystals on the surface. The driving forces for the formation of close-packed crystal involve electrostatic interaction and lateral capillary force, and the ion diffusion during the evaporation is considered to be an important factor for the successful assembly of ordered structure on the latex surface. Then the sol-gel solution was infiltrated into the interstitial space of the prepared colloidal crystals through capillary effect, and ordered inverse opals were obtained by calcining the polystyrene beads. The inverse opal thus prepared has long-range ordering with its defect-free area extending to over 10 micrometers and covering thousands of pores.
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Record 36 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Fluorescence study of chromophore labeled strong polyelectrolyte bound with oppositely charged surfactant
Source: COLLOID AND POLYMER SCIENCE, 280 (9): 814-821 SEP 2002
Abstract: Four strong polyelectrolyte samples of 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) and N,N-dimethylacrylamide (DMAA) were radically copolymerized with a single label of naphthalene or pyrene, with both labels and without label. containing, about 40 mol % AMPS. Fluorescence nonradiative energy transfer (NRET) IPy/INp, anisotropy r, I-1/I-3 and excimer emission I-E/I-M, of pyrene labels were observed in dilute aqueous solutions with and without cationic surfactant of cetyltrimethylammonium bromide (CTAB). The overlap concentration as determined as 3 g L from the appearance of intermolecular excimer. The variation of intra- and intermolecular NRET with total polyelectrolyte concentration showed that the charged chains preferentially interpenetrated each other rather than reduce their coil volume as their concentration beyond the overlap threshold. By binding with CTAB, the polyelectrolyte chain became more coiled as known from the reduced viscosity. The intramolecular NRET was dominant when [CTAB] less than or equal to 4x10(5) M and then the intermolecular NRET occurred at higher CTAB concentrations with hydrophobic aggregation between CTAB tails bound on different polyelectrolyte chains. The CTAB concentration corresponding to the maxima of I-Py/I-Np just is equal to the AMPS monomer concentration, indicating, the formation of 1:1 binding between surfactant and polyelectrolyte in very dilute solutions. Added salt of NaCl up to 0.1 M hardly affected the intramolecular NRET but affected the I-Py/I-Np value for the intermolecular NRET.
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Record 37 of 70
Author(s): Liu, P; Tong, Z; Deng, WJ
Title: Synthesis and gel-forming properties of a novel class or oligothiophene derivatives
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 23 (8): 1632-1637 AUG 2002
Abstract: In order to develop a novel class of low molecular-weight organic gels and to gain an insight into the relationship between molecular structure of gel-forming compounds and gel-forming properties, a novel family of low molecular-weight organic compounds containing terthiophene and tetrathiophene, N,N'-distearyl-5,5"-(2,2' : 5' 2"-torthiophene)dicarboxamide(DNC(n)DOc3T), N,N'-dialkyl-5,5"-(3,3"-dioctyl-2, 2' : 5' 2"-terthiophene) dicarboxamidc (DNC(n)DOc3T, n = 5, 8, 16, 18) and N, N'-distearyl-5, 5"-(3, 3"-dioctyl-2,2' - 5', 2" : 5" 2"-tetrathiophene) dicarboxamide (DNC(18)DOc4T), were designed and synthesized. Whereas DNC(18)3T and DNC(5)DOc3T did not form gels with organic solvents, DNC(n)DOc3T(n =8, 16, 18) and DNCgDOc4T were found to form gels with certain organic solvents. These are the first examples of low molecular-weight organic gels containing an oligothiophone moiety. It is of interest to note that while DNC(8)DOc3T forms opaque gels with alcohols, such as ethanol and isopropanol, DNC(16)DOc3T, DNC(18)DOc3T and DNC(18)DOc4T formed transparent gels with hydrocarbon solvents such as heptane, octane undecane and others. It is shown that the intermolecular hydrogen bonding and intermolecular interaction between the long alkyl chain in the N-alkylcarboxamide group as well as the incorporation of an alkyl group at the P-position of the thiophene ring play an important role for the formation of gels. The xerogel showed three-dimensional networks of fibrous bundle structure. DNC(18)DOc3T/benzonitrile gel and DNC(18)DOc4T/benzonitrile gel were found to function as a new type of electrochromic materials, exhibiting a reversible color changes on electrochemical oxidation and reduction.
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Record 38 of 70
Author(s): Zeng, F; Sun, ZW; Wu, SZ; Liu, XX; Wang, ZY; Tong, Z
Title: Preparation of highly charged, monodisperse nanospheres
Source: MACROMOLECULAR CHEMISTRY AND PHYSICS, 203 (4): 673-677 MAR 15 2002
Abstract: A two stage shot growth emulsifier-free polymerization was applied to prepare styrene(St)/sodium styrenesulfonate (NaSS) latices. The latex particles prepared in the pure water medium were monodisperse and highly charged spheres, but their particle diameters were all higher than 120 nm. By using the two-stage shot growth copolymerization at 70 degreesC in the mixed reaction medium of water and acetone, we successfully prepared monodisperse, highly charged nanospheres with the smallest particle diameter of 89 nm. As the acetone content in the mixed reaction medium was increased to an acetone/H2O ratio of around 0.125, the particle diameter decreased to minimum, and then the particle diameters increased with increasing acetone content in the mixed reaction medium. The conversion-time curves for the first stage emulsifier-free copolymerization of St/NaSS in the mixed reaction medium with varied acetone contents show that the polymerization rate first increased with increasing acetone content, and then decreased. The enhanced rate of polymerization in the lower acetone content results from the increase in the number of primary particle in the reaction medium. As the acetone content was further increased, the solubility of St in the reaction medium further increased, making the copolymerization somewhat like the dispersion polymerization and thus causing increased particle size.
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Record 39 of 70
Author(s): Liu, P; Liang, D; Tong, Z; Liu, XX
Title: Synthesis and luminescence properties of novel europium and terbium complexes with triblock copolymer ligand
Source: MACROMOLECULES, 35 (5): 1487-1488 FEB 26 2002
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Record 40 of 70
Author(s): Wu, SZ; Zeng, F; Li, FX; Tong, Z
Title: Phase stability of the photoconductive polysiloxane-based photorefractive composites
Source: POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, 40 (5): 627-634 2001
Abstract: This article discusses the phase stability of the photoconductive poly siloxane-based photorefractive composites as studied by the light-scattering method. The photorefractive properties of the composites were studied by the two-beam coupling technique. The effects of the electric field on the photorefractive property of the composites were investigated as well. The phase stability was found to be dependent on the chromophore concentration and storage temperature. The two-beam coupling gain coefficient of the composites increased with increasing electric field and chromophore content.
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Record 41 of 70
Author(s): Liu, P; Tong, Z
Title: A novel greenish blue-emitting amorphous molecular material: 2,5-bis{4-[2-naphthyl(phenyl)amino]phenyl}thiophene
Source: CHINESE JOURNAL OF CHEMISTRY, 19 (10): 979-982 OCT 2001
Abstract: A novel greenish blue-emitting amorphous molecular material, 2,5-bis {4-[2-naphthyl(phenyl) amino] phenyl}thiophene (BN-pA-1T), was designed and synthesized. Its molecular properties, glass-forming property, and application to an organic EL device were investigated.
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Record 42 of 70
Author(s): Wang, CY; Sun, QL; Tong, Z; Liu, XX; Zeng, F; Gao, F
Title: Binding of ionic derivative of pyrene to strong polyelectrolyte
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 22 (7): 1265-1267 JUL 2001
Abstract: Binding of pyrene probe cation of 1-pyrenemethylamine hydrochloride (PyMeAH(+)) to sulfonate polyelectrolyte PAMPS in aqueous solution was investigated by the relative fluorescent intensity I-E/I-M of the excimer to monomer. The saturation amount of repeat unit AMPS for the polyelectrolyte bound to one PyMeAH(+) ion was about 2.5 estimated from the maximum on the curve of I-E/I-M vs. the probe concentrations. The increase of the ionic strength of the solution by adding salt or excess alkali ions of 10(-4) mol/L greatly reduced the I-E/I-M value. This fact suggested that the probe cation PyMeAH+ form a loose ion pair with the sulfonate anion on the polyelectrolyte.
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Record 43 of 70
Author(s): Wang, C; Sun, Q; Tong, Z; Liu, X; Zeng, F; Wu, S
Title: Interaction of cetyltrimethylammonium bromide and poly(2-(acrylamido)-2-methyl-propanesulfonic acid) in aqueous solutions determined by excimer fluorescence
Source: COLLOID AND POLYMER SCIENCE, 279 (7): 664-670 JUL 2001
Abstract: The binding interaction of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic poly(2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in dilute aqueous solutions was studied using the excimer fluorescent emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA . HCl). In the absence of CTAB, the saturation binding of PyMeAH(+) on PAMPS is about 2.4 AMPS repeat units for one probe cation as determined by the relative emission intensity, I-E/I-M, of the excimer to monomer. With increasing CTAB concentration, I-E/ I-M firstly increases, reaches a maximum, then decreases to zero. The I-E/I-M maximum indicates a critical aggregation concentration (cac) of 10(-5) mol/l for CTAB in PAMPS solutions. The CTAB concentration at which I-E/I-M is zero is exactly equal to the PAMPS concentration, indicating that the probe cation is thoroughly excluded from the binding site of PAMPS by the CTAB cation and the equivalent stoichiometric aggregation is formed between CTAB and PAMPS. The blueshift of the excimer emission and the excitation spectra shows that the decrease of I-E/I-M with increasing CTAB concentration above the cac is caused mainly by the decrease of the static excimer.
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Record 44 of 70
Author(s): Yang, YY; Zeng, F; Xie, XL; Tong, Z; Liu, XX
Title: Phase separation and network formation in poly(vinyl methyl ether)/water solutions
Source: POLYMER JOURNAL, 33 (5): 399-403 2001
Abstract: Cloud point temperature T-clo and dynamic moduli were measured on aqueous solutions of two poly(vinyl methyl ether) (PVME) samples with molecular weight of 1.16 X 10(4) and 2.57 X 10(4), respectively and M-w/M-n = 1.84 for both samples. The T,I, at which the solution becomes turbid is at around 32.5 degreesC without obvious molecular weight dependence due to their broad molecular weight distribution. The frequency omega dependence of the storage modulus G' and loss modulus G" observed within linear viscoelasticity region indicates that the PVME/water solution exhibits homogeneous fluid behavior at 25 degreesC below T-clo, while shows a plateau zone for G' at 34 degreesC above T-clo, suggesting the appearance of network structure at this temperature. A sharp increase in G' and G" was observed at about 32.5 degreesC with increasing temperature of a PVME/water solution, indicating that at this temperature the network begin to form. These results imply that the network structure is formed accompanying the phase separation in PVME/water solutions due to the hydrophobic bonding between polymer chains.
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Record 45 of 70
Author(s): Ren, BY; Tong, Z; Gao, F; Liu, XX; Zeng, F
Title: Fluorescence and X-ray diffraction studies on binding and complexes of surfactants and dansylated polyelectrolytes with sulfonate groups
Source: POLYMER, 42 (17): 7291-7298 AUG 2001
Abstract: Binding of cationic surfactant cetyltrimethylammonium bromide (CTAB) on polyelectrolytes ADDan containing different amounts of sulfonate groups was studied by fluorescence spectrum of dansyl labels in aqueous solution. With increasing concentration of CTAB, there was an abrupt drop in the emission maximum wavelength lambda (em) and a sharp increase in the relative intensity RF defined as the ratio of emission in the presence of CTAB to that without CTAB. The critical aggregation concentration (cac) determined from the former was about 3 x 10(-5) mol/l without obvious dependence on polymer charge density. Solid complex films of polyelectrolyte-surfactant of CTAB or dodecyltrimethylammonium chloride (DTAC) were obtained by precipitation and their fluorescence anisotropy r indicated a high mobility of the dansyl chromophore. The r-value for ADDan-CTAB complexes obviously decreased as the charge density of the polyelectrolyte increased while the r for ADDan-DTAC complexes was slight decline, suggesting the contribution of alkyl tails of the surfactant to local mobility. It was the first time to find that the higher the charge density of the polyelectrolyte, the less polar the micellar aggregation of polyelectrolyte-surfactant complex becomes in dilute aqueous solution, which remains in the solid complex. SAXS of the solid complexes illustrated a long-range ordered lamella structure with the long period d of 3.87 and 3.04 nm for CTAB and DTAC complexes, respectively. (C) 2001 Published by Elsevier Science Ltd.
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Record 46 of 70
Author(s): Yang, YY; Zeng, F; Tong, Z; Liu, XX; Wu, SZ
Title: Phase separation in poly(N-isopropyl acrylamide)/water solutions. II. Salt effects on cloud-point curves and gelation
Source: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 39 (9): 901-907 MAY 1 2001
Abstract: The cloud-point temperatures (T-clo's) of poly(N-isopropyl acrylamide) (PNI-PAM)/water solutions with NaCl, NaBr, or NaI were measured. All these salts reduced the T-clo's of PNIPAM/water solutions to different extents, in the following order: NaCl > NaBr > NaI. The higher the concentration of the added salt was, the more greatly T-clo dropped. A dynamic viscoelasticity investigation of the PNIPAM/water solutions with the salts indicated that during phase separation, the system changed from a homogeneous fluid into a physically crosslinked network, and the addition of salts also reduced the temperature at which this change began. The gelation temperature (T-gel,) and the scaling exponent of the PNIPAM/water solutions with NaBr were obtained with dynamic scaling theory, and T-gel was found to be close to T-clo. That the addition of salts to the solution decreased T-clo and T-gel to the same extent further proved that the network structure was formed with the phase separation in the PNIPAM/water solutions. (C) 2001 John Wiley & Sons, Inc.
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Record 47 of 70
Author(s): Zeng, F; Wu, SZ; Li, FX; Tong, Z
Title: Temperature dependence of the photorefractive property of PMMA-based composite
Source: EUROPEAN POLYMER JOURNAL, 37 (3): 459-462 MAR 2001
Abstract: Temperature dependence of the photorefractive (PR) property of poly(methyl methacrylate) (PMMA)-based polymer composite is presented. The electrooptic and PR properties of PMMA-based polymer composite have been studied in the temperature range of 22-60 degreesC. The effects of electric field on the PR property of the material have been investigated as well. The experimental results show that the electrooptic coefficient first increases slightly with the enhancing temperature and eventually saturates. This behavior is attributed to the temperature activated orientational mobility of the second-order nonlinear chromophores. Diffraction efficiency first increases with the increasing temperature, and then decreases as the temperature is further enhanced; while the diffraction efficiency increases with the increasing field strength. (C) 2001 Elsevier Science Ltd. All rights reserved.
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Record 48 of 70
Author(s): Ren, BY; Tong, Z; Gao, F; Liu, XX; Zeng, F
Title: Charge density effects on the fluorescence behavior of dansyl labels to strong polyelectrolytes
Source: POLYMER, 42 (5): 2001-2006 MAR 2001
Abstract: Fluorescent spectra of dansyl-labeled copolymers containing 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethyl-acrylamide (DMAA) with 0.2 mol% chromophore were observed in aqueous solution. Two emission bands appeared at 336 and 533 nm for protonated and unprotonated species of the label, respectively. These wavelengths were independent of the mole fraction F-AMPS of AMPS ranging from 0.186 to 0.738 but the relative intensity I-336/I-533 increased proportionally to F-AMPS. The locally excited emission (LE), b* band of the dansyl label was found at. 405 nm when the chromophore concentration was decreased below 1.45 x 10(-5) mol/l. With increasing charge density in the solid copolymer the b* band was strengthened and the a* band for the twisted intramolecular charge-transfer state was weakened and even disappeared owing to the existence of ion-pair attractions. It was found that for the copolymer in dimethyl sulfoxide (DMSO)/tetrahydrofuran (THF) mixtures the change in charge density did not alter the emission wavelength lambda (em) of the a* band. The charge density dependence fur the threshold of DMSO/THF composition, at which the relative emission intensity RF abruptly decreased, was similar to that inducing the volume phase transition in the corresponding polyelectrolyte gels. (C) 2000 Elsevier Science Ltd. All rights reserved.
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Record 49 of 70
Author(s): Tong, Z; Ren, BY; Gao, F
Title: Dual behavior of polyelectrolyte and ionomer for an ionizable polymer containing sulfonate groups in DMSO/THF mixtures
Source: POLYMER, 42 (1): 143-149 JAN 2001
Abstract: A dansyl labeled polyelectrolyte (ADDan60) was prepared by copolymerization of ionizable monomer 2-(acrylamido)-2-methylpropanesulphonic acid (AMPS) with N,N-dimethylacrylamide (DMAA) and N-[2-[[[5-(N,N-dimethylamino)-1-naphthalenyl]-sulfonyl]amino]ethyl]-2-propenamide (DANSAEP, 0.2 mol%). Reduced viscosity eta(sp)/c, electrolytic conductivity kappa, and fluorescent spectrum of ADDan60 in DMSO/THF mixtures were measured as functions of the volume fraction V-THF Of THF. In the region of V-THF < 0.7, the emission maximum lambda(em), relative intensity R-F of ADDan60 in DMSO/THF to that in DMSO, and anisotropy ratio r indicated that the polymer maintained its solvation layer not to change so much as the bulk solvent and exhibited a polyelectrolyte behavior, as observed from eta(sp)/c and kappa. Once V-THF was beyond 0.70, the solvation layer was changed leading to the ion pair formation in an avalanche manner, which induced chain aggregation and phase transition due to the dipole attraction. The results suggest a behavior transition in ionizable polymers from polyelectrolyte into ionomer induced by medium polarity. (C) 2000 Elsevier Science Ltd. All rights reserved.
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Record 50 of 70
Author(s): Zeng, F; Liu, XX; Tong, Z; Yang, YY; Wu, SZ
Title: Thermal reversible gelation during phase separation of poly(N-isopropyl acrylamide)/water solution
Source: SCIENCE IN CHINA SERIES B-CHEMISTRY, 43 (4): 428-434 AUG 2000
Abstract: By dynamic viscoelastic measurement for PNIPAM/water solution it has been found that below the phase separation temperature (about 32 degrees C), the system is homogeneous fluid; while upon being heated to about 32 degrees C, the solution undergoes phase separation and the storage modulus G' increases sharply and exceeds the loss modulus G", indicating the physical network formation during the phase separation. Based on the percolation model, the gel points T-gel were obtained by applying the dynamic seating theory (DST) and Winter's criterion. The critical exponent n was also obtained to be 0.79 through DST, which is different from 0.67, the critical point of chemically crosslinked network predicted through DST. The obtained n value reflects the special property of physical network being different from chemical network.
Record 51 of 70
Author(s): Gao, F; Yan, Y; Ren, BY; Tong, Z
Title: Fluorescence spectra of pyrene labeled polyelectrolytes with sulfonate groups in water and DMSO
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 21 (6): 976-979 JUN 2000
Abstract: 1-Pyrenylmethyl-methacrylamide (PyMA) was synthesized, and applied to copolymerizing with AMPS and DMAA to get a series of pyrene labeled polymers with sulfonate groups. The molar fraction of sulfonate monomer AMPS in these samples varies from 0. 032 6 to 0. 896. In DMSO and water, the profile of fluorescence spectrum of pyrene labeled polyelectrolytes is analogous to that of PyMA when F-AMPS < 0. 449, while the [0,1] emission peak abruptly increased as F-AMPS greater than or equal to 0. 449, The so-called polarity scale of pyrene, I-1/I-3 Of pyrene labeled polyelectrolytes in DMSO and in water decreases gradually with increasing FAMPS representing the charge density of the samples. I-1/I-3 also decreases gradually with the increase in polymer concentration in water. The results imply that there exists the hydrophobic aggregation through locally electrostatic attraction even in polyelectrolyte/polar solvent system, in contrast to the traditional polyelectrolyte theory. However, I-1/I-3 Of these polyelectrolytes remains almost a constant with increasing NaCl concentration of aqueous solution up to 0. 75 mol/L, indicating the electrostatic attraction cannot be simply screened.
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Record 52 of 70
Author(s): Gao, F; Ren, BY; Yan, Y; Tong, Z
Title: Changes in solvation state of strong polyelectrolytes in DMSO/THF mixtures
Source: ACTA PHYSICO-CHIMICA SINICA, 16 (5): 450-453 MAY 2000
Abstract: The fluorescent spectra of two series of sulfonated polyelectrolytes respectively labeled with dansyl and pyrenyl groups were determined as a function of volume fraction phi(THF) of THF in DMSO/THF mixed solvents. When phi(THF) less than or equal to 0.65, the maximum wavelength lambda(em) and the intensity RF relative to that in DMSO for a* band of dansylated samples, as well as I-1/I-3 for pyrene labeled samples varied slightly with increasing (phi(THF), indicating the capability of polyelectrolyte to maintain its chain solvation stable. As long as phi(THF) beyond 0.70, there was an abrupt drop in R-F and lambda(em) showing the sudden change in the chain solvation layer. I-1/I-3 decreased with an increase in the charge density of polyelectrolyte samples, suggesting the existence of aggregated structure even in pure DMSO.
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Record 53 of 70
Author(s): Tong, Z; Zeng, F; Zheng, X; Sato, T
Title: Inverse molecular weight dependence of cloud points for aqueous poly(N-isopropylacrylamide) solutions
Source: MACROMOLECULES, 32 (13): 4488-4490 JUN 29 1999
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Record 54 of 70
Author(s): Ren, BY; Gao, F; Tong, Z; Yan, Y
Title: Solvent polarity scale on the fluorescence spectra of a dansyl monomer copolymerizable in aqueous media
Source: CHEMICAL PHYSICS LETTERS, 307 (1-2): 55-61 JUN 25 1999
Abstract: A copolymerizable fluorescent monomer N-[2-[[[5 -(N,N-dimethylamino)-1-naphthalenyl] sulfonyl]-amino]ethyl]-2-propenamide (DANSAEP) was synthesized, which exhibits dual fluorescence due to the twisted intramolecular charge transfer in the excited state. The emission maximum lambda(em) shifts from 463.3 nm in n-hexane to 530.0 nm in water, showing solvent polarity dependence. The relations between lambda(em) and the conventional solvent polarity parameters E-T(30) or Z are linear, dividing solvents into protic and aprotic groups. Kamlet's linear solvation energy relationship gives a good description for lambda(em) as a solvent polarity scale. The increment of dipole moment Delta mu at the excited state was estimated as 5.09 D with the solvatochromic analysis. (C) 1999 Elsevier Science B.V. All rights reserved.
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Record 55 of 70
Author(s): Zeng, F; Tong, Z; Sato, T
Title: Molecular chain properties of poly( N-isopropyl acrylamide)
Source: SCIENCE IN CHINA SERIES B-CHEMISTRY, 42 (3): 290-297 JUN 1999
Abstract: A series of poly( N-isopropyl acrylamide) (PNIPAM) samples with molecular weight ranging from 2.23 x 10(4) to 130 x 10(4) and molecular weight distribution M-w/M-n less than or equal to 1.28 were obtained by free radical polymerization and repeat precipitation fractionation. The molecular weight M-w, second virial coefficient A(2) as well as the mean-square-root radius of gyration [S-2] for PNIPAM samples in tetrahydrofuran (THF) were determined by light scattering, and the relations were estimated at A(2) proportional to M-w(-0.25) and [S-2](1/2) = 1.56 x 10(-9) M-w(0.56). The intrinsic viscosity for THF: solution and methanol solution of PNIPAM samples was measured and the Mark-Houwink equations were obtained as [ eta] = 6.90 x 10(-5) M-0.73 (THF solution) and [eta] = 1.07 x 10(-4) M-0.71 (methanol solution). The above results indicate that both THF and methanol are good solvents for PNIPAM. The limit characteristic ratio C-infinity for PNIPAM in the two solutions was determined to be 10.6 by using Kurata-Stockmayer equation, indicating that the flexibility of PNIPAM chain is close to that of polystyrene. The intrinsic viscosity for the aqueous solution of PNIPAM was measured at 25-30.5 degrees C. The result demonstrates that PNIPAM chain begins to shrink at 25 degrees C, and from about 30 degrees C onward the molecular chain shrinks much more sharply till the solution becomes macroscopically unstable at 32 degrees C.
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Record 56 of 70
Author(s): Liu, XX; Tong, Z; Gao, F
Title: Novel shrinking-swelling hysteresis in DMSO/THF mixtures of copolymer gels containing sulphonate groups
Source: POLYMER INTERNATIONAL, 47 (2): 215-220 OCT 1998
Abstract: The swelling volume of copolymer gels made from 2-(acrylamido)-2-methylpropanesulphonic acid (AMPS; electrolyte monomer), N,N-dimethylacrylamide (DMAA; comonomer) and N,N'-methylenebis(acrylamide) (BIS; crosslinker) was measured in mixtures of two organic solvents, dimethyl sulphoxide (DMSO) and tetrahydrofuran (THF) at 25 degrees C. A volume phase transition was observed in the gels having 43.18 mol% AMPS with different counterions K+, Na+ and H+, when the THF concentration in the mixture increased beyond a certain value. We observed a swelling-hysteresis between the shrinking and swelling curves, i.e. more DMSO was required to make a shrunk gel start to swell again than to cause the volume shrinking. This hysteresis stems from the formation of ion pairs and/or multiplets in the ionizable gels when the medium polarity is decreased. An excess of DMSO is required to reduce the ionization energy for making the shrunk gel swell again in the DMSO/THF mixture. These aggregates and multiplets do not seem to be entirely removed by the swelling process and act as additional physical crosslinks, so that the DMSO concentration required to induce the shrunk gel to swell becomes higher in the next swelling process, showing another hysteresis. The release of bound water from the solvating layer after shrinkage may be another possible reason for this hysteresis. (C) 1998 Society of Chemical Industry.
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Record 57 of 70
Author(s): Zheng, X; Tong, Z; Xie, XL; Zeng, F
Title: Phase separation in poly(N-isopropyl acrylamide) water solutions I. Cloud point curves and microgelation
Source: POLYMER JOURNAL, 30 (4): 284-288 1998
Abstract: Cloud point curve was determined on binary and ternary aqueous solutions of several fractionated poly(N-isopropyl acrylamide) (PNIPA) samples with the molecular weight M-eta = 11.3 x 10(4)-210 x 10(4) and the molecular weight distribution M-w/M-n = 1.21-1.62. In both the binary and ternary solutions, the cloud point temperature T-clo slightly increases viith the increase in molecular weight of PNIPA. The concentration dependence for the binary solution is weak while it becomes obvious for the ternary solution containing two different PNIPA samples in water; i.e., the molecular weight distribution alters the shape of the cloud point currie. The storage and loss moduli G' and G " for the PNIPA sample of M-eta = 210 x 10(4) in water at concentrations 2.2-8.5 wt% were measured at several temperatures encompassing the T-clo. The results indicate that the solution changes from a homogeneous fluid into viscoelastic microgels suspended in a liquid phase during the phase separation. This physical network is considered to be jointed via the intermolecular hydrophobic bonding between the N-isopropyl groups, which may provide a model system for the structure change or proteins induced in the denaturation.
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Record 58 of 70
Author(s): Liu, XX; Hu, O; Tong, Z; Gu, J
Title: Volume phase transition of copolymerized sulfonic acid gels in mixed organic solvents
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 19 (3): 460-463 MAR 1998
Abstract: Radical copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) with 2-hydropropyl methacrylate (HPM) was conducted in ethylene glycol/water (1:1 in weight) at 70 degrees C. The azeotropic composition was found at the monomer molar ratio of AMPS/HPM as 8/2, Three sulfonic gels were prepared at this composition with the crosslinker N,N'-methylene-bis(acrylamide) of 2%, 3% and 5% (molar percentage), and referred to as G02, G03 and G05, respectively, As expected from their polyelectrolyte nature, these gels swell in dimethyl sulfoxide(DMSO) but shrink in tetrahydrofuran(THF) at 25 degrees C, The volume phase transition takes place in the G02 and G03 swollen in DMSO/THF mixtures when THF content is increased beyond 55%similar to 60% (volume ratio), In ethanol/THF mixture, however, no volume phase transition was found though the gel still shrunk with increasing THF. The dipole-dipole interaction model in less-polar medium was adopted to interpret these results with the concept of preferential solvation.
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Record 59 of 70
Author(s): Zeng, F; Zheng, X; Tong, Z
Title: Network formation in poly(N-isopropyl acrylamide) water solutions during phase separation
Source: POLYMER, 39 (5): 1249-1251 MAR 1998
Abstract: Evidence from dynamic viscoelasticity measurements has been found for reversible network formation via the physical association of hydrophobic side-groups during phase separation at around 33 degrees C in a 1.22 wt.% aqueous solution of poly(hi-isopropyl acrylamide) (PNIPA) having a molecular weight of 2.1 x 10(6). The frequency omega dependence of the dynamic storage and loss moduli G' and G " showed homogeneous fluid behaviour at 25 degrees C, while at 35 degrees C, a plateau zone was found in the G' versus omega curve and G' was larger than G ", indicating the formation of a network. The increase in G' was instantaneous at the phase separation temperature and was not a progressive process. (C) 1997 Elsevier Science Ltd. All rights reserved.
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Record 60 of 70
Author(s): Zeng, F; Tong, Z; Yang, XZ
Title: Differences in vibrational spectra of poly(N-isopropyl acrylamide) from water solution before and after phase separation
Source: EUROPEAN POLYMER JOURNAL, 33 (9): 1553-1556 SEP 1997
Abstract: Two poly(N-isopropyl acrylamide) (PNIPA) samples were prepared by drying the 5 wt% water solution of PNIPA either at 25 degrees C without phase separation (referred to as I-B) or at 38 degrees C after phase separation (I-C). PNIPA sample I-A was directly cast from its acetone solution. The IR absorbance of CH3 asymmetric stretch related to the CH2 symmetric stretch is higher for the samples I-C and I-A when compared with the same absorbance ratio for the sample I-B. At the same time, the vibration frequencies of amide I and II for I-C are similar to those for I-A, but obviously different from those for I-B. Raman scattering intensities corresponding to the CH3 and CH2 vibrations also depend on the sample preparation methods. A simple model simulation suggests that the above observations would be attributed to the configuration change in the side chain of the amide group. The trans isomer is dominant in sample I-B and cis isomer dominant in samples I-A and I-C. (C) 1997 Elsevier Science Ltd.
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Record 61 of 70
Author(s): Zeng, F; Tong, Z; Feng, HQ
Title: Nmr investigation of phase separation in poly(N-isopropyl acrylamide)/water solutions
Source: POLYMER, 38 (22): 5539-5544 OCT 1997
Abstract: H-1 and C-13 n.m.r. spectra of poly(N-isopropyl acrylamide) (PNIPA) in D2O and CDCl3 were measured at several temperatures encompassing the lower critical solution temperature (LCST) about 32 degrees C of the PNIPA/water solution, using a high resolution n.m.r. spectrometer (500 MHz for proton). The PNIPA/CDCl3 is homogeneous in the temperature ranging from 16 to 36 degrees C and the hydrogen bonds of the amide groups are weakened by the solvation of CDCl3 and broken by heating. In the PNIPA/D2O solution, the proton and C-13 spectra are well resolved below the LCST. Whereas at temperatures above the LCST, all the resonance peaks except that for water proton became broad and the spectra lost their fine structure. The integral intensity of the water proton relative to that of the lone proton in the isopropyl group increases with increasing temperature, suggesting that some water molecules appear to be released out of the hydrated shells around the polymer chains. When the solution was heated from 22 to 35 degrees C, the spin-lattice relaxation time T-1 for the proton of the methyl group in the isopropyl residue increased, while that for the protons of the methylene and methyne groups of the backbone chain decreased. This indicates that during heating the relaxation of the isopropyl side chain slows down and that of the main chain speeds up. The phase separation was qualitatively interpreted with the Nemethy-Scheraga model for the hydrophobic bonding. (C) 1997 Elsevier Science Ltd.
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Record 62 of 70
Author(s): Liu, XX; Hu, O; Tong, Z
Title: Viscosity behavior of polyelectrolyte copolymers containing sulfonate groups in mixed organic solvents
Source: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 35 (9): 1433-1438 JUL 15 1997
Abstract: Copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS, monomer I)with 2-hydropropyl methacrylate (HPM, monomer 2) was conducted in ethylene glycol/water (1 : 1 in weight) at 70 degrees C. The reactivity ratios estimated from the copolymer composition at low conversion are r(1) = 2.31 +/- 0.25 and r(2) = 11.70 +/- 1.05. The azeotropic composition was found at the monomer mole ratio AMPS/HPM equal to 8/2. Viscosity of these copolymers was measured in dimethyl sulfoxide (DMSO) and DMSO/tetrahydrofuran (THF) mixed solvent at 25 +/- 0.05 degrees C. Polyeletrolyte behavior was observed for all the copolymers, even in the mixed solvent containing 65 wt % of THF. The reduced viscosity at constant polymer concentration decreased with increasing THF content in the mixed solvent. The copolymers having AMPS repeat units more than 42 mol % precipitated in the mixed solvent when the THF was beyond 68 wt %. The viscosity reduction and precipitation in the copolymer solutions with increasing THF can be attributed to the dipole-dipole attraction between ion-pairs formed in less-polar medium. This is helpful in understanding the volume phase transition in highly charged hydrogels caused by mixing solvents. (C) 1997 John Wiley & Sons, Inc.
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Record 63 of 70
Author(s): Liu, XX; Tong, Z; Cao, XW; Hu, O
Title: Volume phase transition of polyelectrolyte gels in dimethyl sulfoxide/tetrahydrofuran mixtures
Source: POLYMER, 37 (26): 5947-5949 DEC 1996
Abstract: Copolymer gels were prepared from 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), N,N-dimethylacrylamide (DMAA, comonomer) and N,N'-methylenebis(acrylamide) (BIS). The mole fraction of AMPS were 0.2674 and 0.4318, respectively, with the same BIS mole fraction of 0.013. These gels with counterions H+, Na+, and K+ were swollen at 25 degrees C in mixtures of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF). A volume phase transition was observed at the THF volume fraction of about 0.58, indicating that the volume phase transition in a polyelectrolyte gel occurs when the medium polarity decreases sufficiently for ion-pair formation. On changing the counterion, the fraction of DMSO in the solvent mixture which is required to initiate swelling decreases in the order Na+, H+, and K+, the same as for counterion condensation in identical gels. Copyright (C) 1996 Elsevier Science Ltd.
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Record 64 of 70
Author(s): TONG, Z; YI, YH; LIU, XX
Title: COPOLYMERIZATION OF 2-ACRYLAMIDO-2-METHYLPROPANE SULFONIC-ACID WITH 2-HYDROPROPYL METHACRYLATE
Source: POLYMER BULLETIN, 35 (5): 591-597 NOV 1995
Abstract: Copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS, monomer 1) with 2-hydropropyl methacrylate (monomer 2) was conducted in pure water at 80 degrees C. The reactivity ratios estimated from the compositional data of the copolymers at low conversion are r(1)=0.04+/-0.04 and r(2)=6.30+/-0.48, and values of Q(1) and e(1) are 0.16 and 1.37, respectively. Copolymer microstructure predicted by statistical calculation shows mean sequence length of M(1) shorter than 2. These results can be attributed to the strong repulsion between the ionized chain radical and charged monomer of AMPS.
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Record 65 of 70
Author(s): LIU, XX; TONG, Z; HU, O
Title: SWELLING EQUILIBRIA OF HYDROGELS WITH SULFONATE GROUPS IN WATER AND IN AQUEOUS SALT-SOLUTIONS
Source: MACROMOLECULES, 28 (11): 3813-3817 MAY 22 1995
Abstract: Swelling equilibria for five sulfonate gels were carried out in water and in aqueous solutions of NaCl, KCl, CaCl2, Na2SO4, K2SO4, and CaSO4 with concentrations ranging from 10(-6) to 1 M;at 25 degrees C. These samples were the same DS series of gels used in our previous paper, which were copolymerized using the ionizable monomer 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), the comonomer N,N-dimethylacrylamide (DMMA), and the cross-linker N,N'-methylenebis(acrylamide) (BIS). The mole fraction f of AMPS in the gel network ranged from 0.0899 to 0.6076. Before swelling the proton in the gel was exchanged by neutralization to the same cation as that in the salt solution to be equilibrated. The swelling capacity increases with increased charge density in the gels and with decreasing salt concentration. NaCl or KCl solutions more concentrated than 1 M were needed to screen the charge interaction in the DS50 (f = 0.4318) and DS70 (f = 0.6076) samples. The swelling ratios of DS50 and DS70 gels swollen in pure water acid in the salt solutions were found to depend on the counterion species in the increasing sequence as Ca2+, Na+, and K+, which cannot be interpreted with the concept of ionic strength. These phenomena seem to be the results of counterion condensation.
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Record 66 of 70
Author(s): TONG, Z; MEISSNER, K; WOLF, BA
Title: PHASE-EQUILIBRIA AND INTERFACIAL-TENSION BETWEEN COEXISTING PHASES FOR THE SYSTEM WATER 2-PROPANOL POLY(ACRYLIC ACID)
Source: MACROMOLECULAR CHEMISTRY AND PHYSICS, 196 (2): 521-527 FEB 1995
Abstract: The cloud point curve, tie-lines and interfacial tensions were measured for solutions of 50 mol-% neutralized (counter-ion Na-circle plus) poly(arylic acid) (mass-average molar mass (M) over bar(w) = 9 700 g/mol; polydispersity index (M) over bar(w)/(M) over bar(w) = 2,0) in the mixed solvent water/2-propanol at 30 degrees C. Due to the non-uniformity of the polymer, the end-points of the tie-lines are not situated on the cloud-point curve. The interfacial tension sigma - determined by means of the spinning drop method - increases in sigmoidal manner with R(t1), the length of the tie-line, expressed in terms of weight fractions. An evaluation of these data in a double-logarithmic plot of sigma.M(-0,5) versus R(t1) yields a critical exponent of 4,23 as compared with 3,85 in the case of binary systems. The dependence of a on w(w), the over-all weight fraction of water in the mixture, can also be expressed as a power-law choosing (w(cw)-w(w))/w(cw) as the concentration variable (w(cw): critical weight fraction of water); for the present system the exponent of the resulting equation amounts to 2,33 as compared with 2,0 for toluene/polyisobutylene/poly(dimethylsiloxane).
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Record 67 of 70
Author(s): TONG, Z; LIU, XX
Title: SWELLING EQUILIBRIA AND VOLUME PHASE-TRANSITION IN HYDROGELS WITH STRONGLY DISSOCIATING ELECTROLYTES
Source: MACROMOLECULES, 27 (3): 844-848 JAN 31 1994
Abstract: Several sulfonic acid copolymer gels were prepared by radical copolymerization of N,N-dimethylacrylamide (DMAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) using N,N'-methylenebisacrylamide (BIS) as the cross-linker. The concentration of pregel solutions and BIS content in dried gels were held constant at 0.75 mol/L and 1.3 mol %, respectively, while the mole fraction f of AMPS in dried gels determined by elemental analysis varied from 0 to 0.608. Swelling ratios for our sample of f = 0.468 were compared with those for an acrylic acid copolymer gel of f = 0.494 and 25 degrees C in aqueous buffers from pH = 2 to pH = 10 at 0.01 M ionic strength, and the results indicated that even in the gel state the sulfonic acid group could dissociate completely in the whole pH range. Therefore, f in this work can be designated to represent the charge density in the swollen gels. The swelling capacity observed in pure water at 25 degrees C increases monotonically with increasing f, showing a higher increasing rate when f > 0.3 without any sign of counterion condensation. The experimental swelling curve was interpreted with the Flory-Huggins theory and with the Hasa-Ilavsky-Dusek (HID) theory, but both theories failed to provide a reasonable approach to the swelling equilibria in our gels with a large amount of strongly dissociating electrolytes. The reciprocal of polymer volume fraction in a swollen gel, 1/phi, predicted with the Flory-Huggins theory was much higher than that observed when f > 0.2, while the calculated results given by the HID theory using the experimental nominal value of chain density were considerably lower than measured data in the entire f range. A volume phase transition occurred in these gels when f > 0 when the acetone volume fraction V-a in the acetone/water mixture was beyond a certain value, and this transition could be attributed to the weakening of electrostatic repulsion during increasing V-a in the mixture.
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Record 68 of 70
Author(s): TONG, Z; LIU, XX
Title: DYNAMIC-MECHANICAL BEHAVIOR OF POLYELECTROLYTE GELS WITH SULFONIC-ACID GROUPS
Source: MACROMOLECULES, 26 (18): 4964-4966 AUG 30 1993
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Record 69 of 70
Author(s): TONG, Z; LIU, XX
Title: SWELLING EQUILIBRIA AND VOLUME PHASE-TRANSITION OF PARTIALLY NEUTRALIZED POLY(ACRYLIC ACID) GELS
Source: EUROPEAN POLYMER JOURNAL, 29 (5): 705-709 MAY 1993
Abstract: Seven ionized gel samples of poly(acrylic acid) made by radical polymerization and having stoichiometric neutralization degree (f) ranging from 0 to 1, were examined. The ionization degree (alpha) is about a half the value of f for each sample. The data of swelling equilibrium in water as a function of alpha were interpreted with the Konak-Bansil equation; fair agreement was obtained if the effect of counterion condensation was considered. Volume phase transition in water/acetone was considered. Volume phase transition in water/acetone mixtures was found for five samples with high alpha values; the acetone concentration needed to induce the transition became lower for samples with higher alpha.
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Record 70 of 70
Author(s): TONG, Z
Title: APPARENT 2ND VIRIAL COEFFICIENT-GAMMA FOR TERNARY SOLUTIONS OF 2 POLYMERS IN A SOLVENT
Source: MACROMOLECULES, 24 (20): 5734-5735 SEP 30 1991
Author(s): Wu, SZ; Wu, YF; Zeng, F; Tong, Z; Zhao, JQ
Title: Tunability of fluorescence property of a terbium-complex-containing polymer via incorporation of a transition-metal complex
Source: MACROMOLECULAR RAPID COMMUNICATIONS, 27 (12): 937-942 JUN 24 2006
Abstract: In this study, a terbium-complex monomer and transition-metal-complex monomers (Fe-III, Mn-II, and Ni-II complex monomers) are synthesized, and novel acrylate copolymers are then obtained through covalent attachment of the terbium complex and the transition-metal complex onto the macromolecular chain simultaneously. The copolymers developed herein present the characteristic fluorescence properties of the terbium(III) ion. The incorporation of an MnII complex into a Tb-III-containing polymer leads to greater fluorescence enhancement compared with the NiII complex, while the incorporation of the FeIII complex results in fluorescence quenching, thus the incorporation of different transition-metal complexes into the copolymers ensures tunability of the copolymer's fluorescence property.
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Record 2 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z; Ren, B; Zeng, F
Title: New loading process and release properties of insulin from polysaccharide microcapsules fabricated through layer-by-layer assembly
Source: JOURNAL OF CONTROLLED RELEASE, 112 (1): 79-87 MAY 1 2006
Abstract: Polysaccharide multilayer rnicrocapsules were fabricated in aqueous media by the layer-by-layer self-assembly of chitosan (CHI) and sodium alginate (ALG) on melamine formaldehyde (MF) microparticles of 2.1 mu m diameter as templates, followed by removal of the templates through dissolving at low pH. The loading process was observed with the confocal laser scattering rnicroscope (CLSM) using fluorescence labeled insulin. Insulin was spontaneously loaded into the ALG/CHI microcapsules at pH below its isoelectric point of 5.5 where insulin was positively charged and the loading capacity increased with pH decreasing from 4.0 to 1.0. Because there exited a negatively charged complex of ALG/MF residues inside the microcapsules formed during the MF particle dissolution. A novel two-temperature loading procedure was proposed as loading at 20 degrees C for the first hour and at a higher loading temperature for the second hour. This procedure was very significant that increasing the second loading temperature from 20 to 60 degrees C not only increased the insulin loading capacity, but also slowed down its release rate. The release rate of insulin at pH 7.4 was found much faster than that at pH 1.4 due to the positive charges on the insulin. Cross-linking the ALG in the microcapsule shell with calcium ions (Ca2+) or re-sealing the microcapsules with additional layers also remarkably decreased the insulin release rate. The results provide a simple method to control the loading and release of protein molecules within these polysaccharide microcapsules. (c) 2006 Elsevier B.V. All rights reserved.
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Record 3 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Tong, Z
Title: Formation of microscopic ordering and macroscopic patterns in solid polyacrylate-tetraoctylammonium bromide films
Source: MACROMOLECULES, 39 (7): 2606-2613 APR 4 2006
Abstract: Previously, we observed the rather unusual macroscopic patterns that formed in the solid films cast from organic solutions containing a surfactant tetraoctylammonium bromide (TOAB) and a chromophorecontaining polymer, and we proposed that the patterns resulted from the phase separation between the polymer-rich amorphous structures and the surfactant-rich mesomorphous structures (Macromolecules 2005, 38, 9266). In this study, it was found that the mesomorphous structure and macroscopic patterns could also form in the solid films cast from a mixture of toluene, TOAB, and polyacrylates with common polar groups like hydroxyl or carboxyl. It was also found that the higher polymer chain mobility as well as the balanced interactions between the three components in the system are crucial to the formation of mesomorphous structure and the macroscopic patterns. The patterns and the ordered mesomorphous structures were found to be destroyed at the elevated temperatures, further proving that the pattern formation needs the participation of solvent. The small-angle X-ray scattering (SAXS) investigations shows that different polar groups in the polymer chains cannot make any difference in SAXS profile in terms of peak position ratios, suggesting that the resultant mesomorphous structures do not change with the type of the polar groups in the polymer chains. These results prove that the ordered supramolecular structures can also be formed in the polymer-surfactant-organic solvent system, and the weak van der Waals interactions can lead to the formation of mesomorphous structures and macroscopic patterns.
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Record 4 of 70
Author(s): Zhao, DL; Ren, BY; Liu, SS; Liu, XX; Tong, Z
Title: A novel photoreversible poly(ferrocenylsilane) with coumarin side group: synthesis, characterization, and electrochemical activities
Source: CHEMICAL COMMUNICATIONS, (7): 779-781 FEB 21 2006
Abstract: A novel poly(ferrocenylsflane) with a coumarin side group was synthesized. This photoreversible polymer exhibits interesting electrochemical activities, which change with photodimerization and photoscission reactions of the coumarin moieties.
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Record 5 of 70
Author(s): Wang, CY; He, CY; Tong, Z; Liu, XX; Ren, BY; Zeng, F
Title: Combination of adsorption by porous CaCO3 microparticles and encapsulation by polyelectrolyte multilayer films for sustained drug delivery
Source: INTERNATIONAL JOURNAL OF PHARMACEUTICS, 308 (1-2): 160-167 FEB 3 2006
Abstract: Combination of adsorption by porous CaCO3 microparticles and encapsulation by polyelectrolyte multilayers via the layer-by-layer (LbL) self-assembly was proposed for sustained drug release. Firstly, porous calcium carbonate microparticles with an average diameter of 5 mu m were prepared for loading a model drug, ibuprofen (IBU). Adsorption of IBU into the pores was characterized by ultraviolet (UV), infrared (IR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) experiment and X-ray diffraction (XRD). The adsorbed IBU amount Gamma was 45.1 mg/g for one-time adsorption and increased with increasing adsorption times. Finally, multilayer films of prolamine sulfate (PRO) and sodium poly(styrene sulfonate) (PSS) were formed on the IBU-loaded CaCO3 n-ftroparticles by the layer-by-layer self-assembly. Amorphous IBU loaded in the pores of the CaCO3 microparticles had a rapider release in the gastric fluid and a slower release in the intestinal fluid, compared with the bare IBU crystals. Polyelectrolyte multilayers assembled on the drug-loaded particles by the LbL reduced the release rate in both fluids. In this work, polymer/inorganic hybrid core-shell microcapsules were fabricated for controlled release of poorly water-soluble drugs. The porous inorganic particles are useful to load drugs in amorphous state and the polyelectrolyte multilayer films coated on the particle assuage the initial burst release. (c) 2005 Elsevier B.V. All rights reserved.
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Record 6 of 70
Author(s): Liu, SS; Wang, CY; Liu, XX; Tong, Z; Ren, BY; Zeng, F
Title: NRET from naphthalene labels in multilayer shell wall on melamine formaldehyde microparticles fabricated with layer-by-layer self-assembly to pyrene-labeled polyelectrolyte in solution
Source: EUROPEAN POLYMER JOURNAL, 42 (1): 161-166 JAN 2006
Abstract: Core-shell colloidal particles were prepared with the core of monodisperse melamine formaldehyde particles (MF) with a diameter of 3.5 mu m. The shell deposited on the core by the layer-by-layer (LbL) self-assembly was made with a copolymer ANp3 of 2-acrylamido-2-methylpropanesulfonate sodium (AMPS) and 3 mol% naphthalene label monomer and poly(diallyldimethylammonium chloride) (PD). Nonradiative energy transfer (NRET) from the naphthalene labels deposited on the MF particles to pyrene labels at a polyelectrolyte APy3, a copolymer of AMPS and 3 mol% pyrene label monomer, or to an ionic pyrene probe 1-pyrenemethylamine hydrochloride (PyMeA (.) HCl) in water was observed. The NRET efficiency was expressed as the emission intensity ratio I/I-0 of naphthalene with and without existence of pyrene in the surrounding solution. With increasing pyrene concentration, I/I-0 decreased down to about 0.2 and the mechanism for this NRET from the inner naphthalene label to the pyrene labels in solution is still ambiguous. (c) 2005 Elsevier Ltd. All rights reserved.
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Record 7 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Luo, SJ; Ren, BY; Tong, Z
Title: Mesomorphous structure and macroscopic patterns formed by polymer and surfactant from organic solutions
Source: MACROMOLECULES, 38 (22): 9266-9274 NOV 1 2005
Abstract: Ordered mesomorphous structures were obtained from the ternary system of organic solvent, polymer, and surfactant, and this microscopic ordering could lead to unique water-wave-like macroscopic patterns in solid polymer-surfactant film. The mesomorphous structures and macroscopic patterns were obtained by dissolving a nonpolyelectrolyte polymer and cationic surfactant in organic solvents and casting the solutions on glass substrates. The patterns thus obtained are composed of concentric rings, and these concentric rings, with their diameters up to centimeters, alternatively consist of macroscopic convex ridges and concave valleys, with the former being amphormous phase and the latter being ordered mesomorphous one. This macroscopic patterning in a solid polymer-surfactant system could offer a new way for fabricating ordered supramolecular structure in macroscopic dimensions.
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Record 8 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z
Title: Deposition temperature effect on release rate of indomethacin microcrystals from microcapsules of layer-by-layer assembled chitosan and alginate multilayer films
Source: JOURNAL OF CONTROLLED RELEASE, 106 (3): 319-328 SEP 2 2005
Abstract: Indomethacin (IDM) microcrystals sized 5 similar to 10 mu m were directly encapsulated with nature polysaccharides chitosan (CHI) and sodium alginate (ALG) through layer-by-layer (LbL) self-assembly. Due to partial dissolution of IDM in the deposition solution, the retention of the IDM microcrystals gradually decreased with increasing deposition times and became 47.7% as 10 layers of polysaccharides formed. The release rate of the IDM from the microcapsules was monitored with UV absorbance. The half release time t(1/2) of IDM in the microcapsule increased with the layer number and the initial burst phenomenon was relieved after encapsulation. It was found that added NaCl did not affect the release rate even up to 0.5 M of its concentration, while increasing the release temperature remarkably speeded up the release process. The prolonged release of the encapsulated IDM was still observed when the aqueous release solution containing 20 vol.% ethanol. It was very significant that increasing deposition temperature from 20 to 60 degrees C reduced the release rate efficiently, owing to the increase in multilayer thickness and formation of a more perfect multilayer film. This finding provides a new and simple method to control the permeability of the LbL assembled multilayer films. Because of the biodegradability of CHI and ALG and various methods to tune the release rate, the LbL self-assembly on drug microcrystals promises high potential for encapsulation used in controlled release. (c) 2005 Elsevier B.V. All rights reserved.
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Record 9 of 70
Author(s): Ye, SQ; Wang, CY; Liu, XX; Tong, Z
Title: Multilayer nanocapsules of polysaccharide chitosan and alginate through layer-by-layer assembly directly on PS nanoparticles for release
Source: JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION, 16 (7): 909-923 2005
Abstract: Polysaccharide multilayer nanocapsules have been fabricated in aqueous media by the layer-by-layer self-assembly of chitosan (CHI) and sodium alginate (ALG) on monodisperse polystyrene (PS) nanoparticles with a diameter of 180 nm as template, followed by removal of the templates through dissolving in THE The pH and added salt concentration of the polyelectrolyte deposition solutions were optimized to ensure the alternating deposition. Consequently, the most suitable pH values were found to be 6.0-8.0 for ALG and 3.5 for CHI and were used in the deposition. The concentration of added NaCl used in the adsorption solutions was 0.5 M, which led to an average thickness of about 13 nm for 5 bilayers of CHI/ALG shell-wall zeta-potential indicated the stepwise and alternating adsorption of CHI and ALG to form multilayer film on the PS nanoparticles. The characteristic bands of PS residue almost disappeared in the IR spectrum of the nanocapsule after dipped in THF, confirming thorough removal of PS templates from the core-shell particles. TEM, SEM and AFM were utilized to observe the nanocapsules of about 225 nm in diameter (by TEM). A hydrophilic drug model, acridine hydrochloride (AH), was chosen to investigate the loading and release properties of the nanocapsules. The positively charged AH spontaneously deposited into the capsule due to the electrostatic interaction with the negatively charged styrene sulfonate residues from the PS template inside the capsule. The rate of AH release became slightly slower when the capsule wall was cross-linked with glutaraldehyde, but the accumulative released amount for the crosslinked capsule was obviously reduced. These nanocapsules made from nature polysaccharides have a potential application in controlled drug release.
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Record 10 of 70
Author(s): Lu, L; Liu, XX; Dai, L; Tong, Z
Title: Difference in concentration dependence of relaxation critical exponent n for alginate solutions at sol-gel transition induced by calcium cations
Source: BIOMACROMOLECULES, 6 (4): 2150-2156 JUL-AUG 2005
Abstract: The sol-gel transition in aqueous alginate solutions induced by chelation with calcium cations from in situ release has been investigated with viscoelastic methods. Two alginate samples having different molecular weights (MW) were used over the concentration C-Alg of 2 similar to 6 wt % with different mole ratio f of Ca2+ to the alginate repeat unit. The gel pointf(gel) and relaxation critical exponent n were determined according to Winter's criterion, the later agrees well with that obtained from the relaxation modulus. The results indicate that the power law is valid for the dynamic relaxation at the gel point and the critical gel possesses the self-similarity in structure. With increasing C-Alg, f(gel) for the alginate with lower MW decreases dramatically and n is almost constant of about 0.71. In contrast, f(gel) for the higher MW alginate with is almost a constant and n decreases from 0.72 then levels off at 0.37 with increasing C-Alg, indicating that the concentration dependence of n varies with MW of alginate in the starting solution. The fractal dimension d(f) estimated from n suggests a denser structure in the critical gel of higher MW alginate. Either n or df has been found to follow one curve for the two samples if plotted against the number of cross-link junctions per polymer chain, which is proportional to the alginate MW.
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Record 11 of 70
Author(s): Ren, BY; Cheng, ZY; Tong, Z; Liu, XX; Wang, CY; Zeng, F
Title: Novel structure change in nonequimolar complexes of linear poly(ethylenimine) and octadecanoic acid: Effects of composition
Source: MACROMOLECULES, 38 (13): 5675-5680 JUN 28 2005
Abstract: Polymer-amphiphile complexes based on specific noncovalent interactions have received considerable attention in recent years due to its simple preparation and interesting properties. However, little attention has been paid to the complex composition effect on the crystal and mesomorphous structure of amphiphile side chains in nonequimolar polymer-amphiphile complexes. The structure of a series of nonequimolar linear poly(ethylenimine)-octadecanoic acid complexes, lPEI-OA-x, with the molar ratio x of OA to the lPEI amino group ranging from 0.66 to 1.45, was investigated with WAXD, SAXS, FTIR, DSC, fluorescence spectrum, and polarized optical microscope. Two crystalline modifications beta(O) (beta-orthorhombic) and beta(T) (beta-triclinic) of OA side chains have been found to coexist in the complexes varying with x, and only 8-10 CH2 groups in an OA molecule participate in the crystallization. The crystalline OA tails with amorphous lPEI form the lamella stacking structure. The complexes of x > 1.0 are predominant with beta(O) form and stacked into an end-to-end bilayer lamella with the long period of similar to 5.6 nm. While for the complexes of x < 1.0, the PT form is dominantly stacked in the interdigitating monolayer structure with the long period of similar to 2.8 nm. The fluorescence emission from pyrene-doped complexes indicates a decrease in the microenvironment polarity with increasing x. The thermotropic liquid crystal state has been observed from the complexes of x < 1.0 at temperatures above the melting point of the OA tail crystal. This study demonstrates that the crystalline and mesomorphous structures of polyelectrolyte-amphiphile complexes can be effectively tuned by changing the relative amount of bound amphiphiles. In other words, the stacking structure of amphiphile molecules depends on the amount of added binding polyelectrolytes.
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Record 12 of 70
Author(s): Sun, QL; Tong, Z; Wang, CY; Ren, BY; Liu, XX; Zeng, F
Title: Charge density threshold for LbL self-assembly and small molecule diffusion in polyelectrolyte multilayer films
Source: POLYMER, 46 (13): 4958-4966 JUN 17 2005
Abstract: Polyelectrolyte multilayer films were prepared via the layer-by-layer self-assembly using poly(diallydimethylammonium chloride) (PDADMAC) and pyrene labeled polyanions of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N,N-dimethylacrylamide copolymers with different charge densities (AMPS mole fraction) F-AMPS = 0.20-0.999. Multilayer growth with alternating deposition from salt-free polyelectrolyte solutions was monitored by fluorescence intensity and film thickness, showing a charge density threshold between 0.574 and 0.711 for our polyanions, below which the multilayer cannot be formed due to desorption in the following depositions. For the fully charged polyanion, thickness of the multilayer film increased with increasing NaCl concentration in the deposition solution; while for other polyanions with lower F-AMPS, little growth in multilayer films was found when NaCl concentration was 0.02 mol/L or higher. The quenching rate of nitromethane to the pyrene label in the multilayer film was adopted to detect the chain density and permeability of these films. Decreasing the charge density, increasing the salt concentration and reducing the layer number will accelerate the quenching rate. The former two is due to the formation of a looser structure in the multilayer films at low charge density of the polyelectrolytes or high salt concentration in the deposition solutions, while the last one is mainly due to the reduction of diffusion distance. (c) 2005 Elsevier Ltd. All rights reserved.
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Record 13 of 70
Author(s): Liang, ZP; Wang, CY; Tong, Z; Ye, WH; Ye, SQ
Title: Bio-catalytic nanoparticles in multilayer assembled throt with urease immobilized gh layer-by-layer technique
Source: REACTIVE & FUNCTIONAL POLYMERS, 63 (1): 85-94 2005
Abstract: A novel core-shell colloid with multilayer for biocatalysis was elaborated by the layer-by-layer assembly technique. Urease was adsorbed in alternation with the oppositely charged polyelectrolytes onto polystyrene (PS) colloid nanoparticles as either polycation or polyanion switched by the solution pH. Microclectrophoresis, transmission electron microscopy (TEM) and UV-vis spectrum absorbance were employed to monitor the regular and stepwise growth of the multilayer films with the enzyme and counterpart polyclectrolytes. The colloid nanoparticles coated with negatively charged urease were found to be more stable than those coated with positively charged urease. The catalytic activity of the urease immobilized on the PS nanoparticles, having higher storage stability, was 23.67% of that for the free urease in aqueous solution. Addition of 0.05 M NaCl increased the activity of the immobilized urease by 65%. Coverage of synthetic polyelectrolyte layers on the urease layer reduced the activity of the immobilized urease. Therefore, by adding salts or covering with polyclectrolytes, we have achieved an enhancement or restraint of the bioactivity of immobilized enzyme, indicating a novel method for biotechnology. (c) 2005 Elsevier B.V. All rights reserved.
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Record 14 of 70
Author(s): Wu, SZ; Zeng, F; Zhu, HP; Tong, Z
Title: Energy and electron transfers in photosensitive chitosan
Source: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 127 (7): 2048-2049 FEB 23 2005
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Record 15 of 70
Author(s): He, CY; Liang, ZP; Wang, CY; Liu, XX; Tong, Z
Title: Immobilization of superoxide dismutase by layer-by-layer assembly on surface of PS colloid particles and their bioactivity
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 26 (1): 88-92 JAN 2005
Abstract: Novel enzyme multilayer films on the surface of polystyrene(PS) colloid particles was fabricated by layer-by-layer (LbL) self-assembly. Superoxide dismutase(SOD) was adsorbed on the PS particles as either polycation or polyanion switched by adjusting pH alternatingly with the oppositely charged polyelectrolytes. zeta-Potential and TEM results indicated the regular and stepwise growth of the multilayer structure. The amount of the immobilized SOD was estimated from the difference in SOD bioactivity of the supernatant after adsorption and SOD solution before adsorption by using the pyrogallol oxidation method. The immobilization amount of SOD was 12 and 51 IU when adsorbed in pH = 8.0 as a polyanion and in pH = 4.3 as a polycation, respectively. However, the relative activity of the former was 23.4% while that of the latter was 2.9%, compared to that of free SOD in aqueous solution. Anionic SOD was found to form more regular and smooth layers on the PS particle surface and cationic SOD to aggregate. By adjusting pH of the adsorption solution we can optimize the assembled status and bioactivity of particle-immobilized enzyme.
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Record 16 of 70
Author(s): Wang, CY; Ren, BY; Tong, Z; Zeng, F; Liu, XX; Wu, SZ; Liu, P
Title: Fluorescence observations on complex formation between linear and hyperbranched polyelectrolytes in dilute aqueous solutions
Source: EUROPEAN POLYMER JOURNAL, 41 (1): 185-191 JAN 2005
Abstract: The complexation between poly(ethylene imine) (PEI) and poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) or AMPS copolymers was investigated with the relative excimer emission intensity I-E/I-M of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA . HCl), fluorescence nonradiative energy transfer (NRET) I-Py/I-Np of naphthalene to pyrene labels, the fluorescence anisotropy r and I-E/I-M of pyrene labels. PEI was a hyperbranched weak polycation in acid solution, which formed complex with anionic polyelectrolytes due to the electrostatic attraction. The I-E/I-M of PyMeA . HCl probe decreased to zero, the intra-, intermolecular NRET I-Py/I-Np and I-E/I-M of pyrene labels on the AMPS copolymers reached their maxima when 7 was increased from 0 to 2.4, which was defined as the mole ratio of the amino group in PEI to the AMPS group in the polyanion. These facts indicated the formation of nonstoichiometric complex of the oppositely charged polyelectrolytes when chi = 2.4 at the concentration much lower than their overlap concentrations. The intermolecular aggregate appeared as indicated by an increase in the intermolecular I-Py/I-Np and r with chi up to 2.4 due to neutralizing and hydrophobizing the polyelectrolytes and the bridging effect of the PEI chain bound on different polyanion chains. At high pH, PEI became a neutral polymer and did not bind with the AMPS anion to form the complex as illustrated by the constant value of r for the pyrene labels attached to the AMPS polyanion as that without addition of PEI. The amino group in PEI quenched pyrene and naphthalene emission, resulting a decrease in both I-Np and I-Py. (C) 2004 Elsevier Ltd. All rights reserved.
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Record 17 of 70
Author(s): Tang, T; Zeng, F; Wu, SZ; Tong, Z; Luo, DB; She, WL
Title: Photo-induced birefringence and all-optical switching effect in azobenzene-grafted polyurethanes
Source: OPTICAL MATERIALS, 27 (3): 585-590 DEC 2004
Abstract: In this study, azobenzene-containing chromophore 4-N,N'-bis-(2-hydroxyethyl)amino-4'-nitro-azobenzene were synthesized by using 4-nitroaniline and m-tolyldiethanoamine. Then they were polymerized with toluene 2,4-di-isocyanate (TDI) and polyethylene glycol (PEG) in N,N'-dimethylformamide (DMF) to obtain novel polyurethanes which exhibit photo-induced birefringence properties. Polyols such as 1,4-dibutanol or tri-hydroxyl propane were introduced into the polyurethane structure to adjust the flexibility of the polymer chain segments. An experimental setup, in which the He-Ne lasers produced signal beams and Ar+ lasers the pump beams, was employed to investigate the photo-induced birefringence and optic-optic switching properties of these polyurethane materials. It is found that, with increasing pump beam power, the extent of both birefringence and optic switching response first slightly increased due to reorientation mechanism, and then decreased due to thermal effects. And the flexibility for the chain segment also has remarkable effects on birefringence extents and optic switching modulations. (C) 2004 Elsevier B.V. All rights reserved.
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Record 18 of 70
Author(s): Ren, BY; Tong, Z; Liu, XX; Wang, CY; Zeng, F
Title: Mesomorphous structure and properties of non-equimolar complexes of poly (ethylenimine) and perfluorooctanoic acid
Source: LANGMUIR, 20 (24): 10737-10743 NOV 23 2004
Abstract: A series of solid complexes, PEI-PFAO, made of poly(ethylenimine) (PEI) and perfluorooctanoic acid (PFOA) with different compositions were prepared through a "starving addition" method, where PFOA was fed into PEI solution at the molar ratio, phi(feed), of acid group to the amino group of PEI, never beyond unity. Wide-angle X-ray diffraction diagrams confirmed amorphous structure of these complexes. Small-angle X-ray scattering indicated two ordered mesomorphous structures of alpha and beta lamellar phases, with respective long periods of 2.29 and 1.15 nm in the complexes. By increasing the actual molar ratio, phi, of PFOA to the amino group of PEI, the complex structure was altered from alpha-phase dominant to beta-phase dominant. All complexes exhibited two thermal degradation processes induced by decomposition of the bound PFOA below 230 degreesC and PEI backbone at about 350 degreesC. The initiating degradation temperature, T-id, decreases with increasing phi due to the preferential degradation of the PFOA chain bound to the tertiary amino groups. The glass transition temperature, T-g, of the complex increases with phi up to the degradation of the complex of phi = 1. This increase in T-g with phi also supports an ordered alignment of the bound PFOA chains, which greatly restricts the PEI mobility. The solid surface tension, gamma(S), and critical surface tension, gamma(C), of the complex are between 15.4 and 16.8 mN/m and between 13.5 and 15.4 mN/m, respectively. The latter is very close to or even smaller than gamma(C) of PTFE (15 mN/m), suggesting the enrichment of CF2 and CF3 groups at the complex surfaces. The fact that the PEI-POFA complex combines high hydrophobicity with selective thermal degradation of bound fluorinated chains promises a potential of selective change and local functionalization of the surface in a well-controlled manner.
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Record 19 of 70
Author(s): Liang, ZP; Wang, CY; Sun, QL; Tong, Z
Title: Novel microcapsule fabricated by LbL nano self-assembly
Source: PROGRESS IN CHEMISTRY, 16 (4): 485-491 JUL 2004
Abstract: The article focuses on a novel and versatile technique of layer-by-layer deposition(LbL), developed for preparing nano- or micro- capsules. The strategy outlined readily affords precise control over the size, composition, construction, shape and wall thickness of the hollow capsules. Consequently these capsules have potential applications in biochemistry, pharmacy, controlled- release, cosmetic and catalyst.
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Record 20 of 70
Author(s): Liu, P; Zhang, YM; Feng, GJ; Hu, JH; Zhou, XP; Zhao, QH; Xu, YH; Tong, Z; Deng, WJ
Title: Synthesis and liquid crystal properties of a novel family of oligothiophene derivatives
Source: TETRAHEDRON, 60 (24): 5259-5264 JUN 7 2004
Abstract: In order to develop novel oligothiophene-based liquid crystals capable of hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N'-dialkyl-5,5"-dichloro-2,2:5',2"-terthiophene-4,4"-dicarboxamide (DNC(n)DCl3T, n=8, 18), N,N"-dialkyl-5,5"-dibromo-2,2':5',2"-terthiophene-4,4"-dicarboxamide (DNC(n)DBr3T, n=5, 8, 16, 18), or N,N'-dialkyl-5,5"-diiodo-2,2:5',2"-terthiophene-4,4"-dica-rboxamide (DNC(n)DI3T, n=8, 18), were designed and synthesized, and their thermal behaviour was examined. It was found that DNC(18)DC13T, DNC(n)DBr3T and DNC(n)DBr3T (n=8, 16, 18) form a smectic A phase and that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding also plays a role in the formation of a liquid crystal phases in the DNC(n)DBr3T system. (C) 2004 Elsevier Ltd. All rights reserved.
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Record 21 of 70
Author(s): Zeng, F; Wu, SZ; Tang, T; Sun, ZW; Wang, CY; Liu, XX; Tong, Z
Title: Preparation of colloidal crystals with polyhedral building blocks through post-polymerization
Source: COLLOID AND POLYMER SCIENCE, 282 (6): 651-655 APR 2004
Abstract: An alternative approach was adopted to prepare colloidal crystal with polyhedral building blocks. First, monodisperse polystyrene particles that contained about 30% wt of monomer were obtained by emulsifier-free emulsion polymerization at 38 degreesC. These monomer-containing particles were used to prepare colloidal crystal on the surface of dispersion, before the spherical particles in the colloidal crystals underwent deformation between two quartz plates at 75 degreesC for 40 min by interfacial tensions, and finally the deformed particles were "frozen" through post-polymerization.
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Record 22 of 70
Author(s): Tong, Z; Wang, CY; Ren, BY; Liu, XX; Zeng, F
Title: Binding of ionic surfactants on oppositely charged polyelectrolytes observed by fluorescence methods
Source: CHINESE JOURNAL OF POLYMER SCIENCE, 21 (6): 609-620 NOV 2003
Abstract: Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity I-E/I-M of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA(.)HCl) and the non-radiative energy transfer (NRET) I-Pv/INp of naphthalene to pyrene for labeled polyelectrolytes were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1 aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1 polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymer-surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.
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Record 23 of 70
Author(s): Wu, SZ; Zeng, F; Yao, SL; Tong, Z; She, WL; Luo, DB
Title: All-optical switching effect in novel chiral biazobenzene polymer films
Source: MACROMOLECULES, 36 (25): 9292-9294 DEC 16 2003
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Record 24 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Binding on strong polyelectrolytes of mixed ionic and nonionic surfactants below their critical micelle concentration observed by fluorescence
Source: COLLOID AND POLYMER SCIENCE, 282 (2): 141-148 DEC 2003
Abstract: The binding of mixed surfactants of cationic cetyltrimethylammonium bromide (CTAB) and nonionic octaethylene glycol monododecyl ether (C12E8) on anionic polyelectrolyte poly[2-acrylamido-2-methylpropanesulfonic acid (PAMPS)] and fluorophore-labeled copolymers containing about 40 mol% of AMPS was investigated at different mole fractions, Y , of CTAB in the surfactant mixture. The excimer emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA.HCl), nonradiative energy transfer (NRET) between pyrene and naphthalene labels and I-1/ I-3 of the pyrene label were determined by varying the total surfactant concentration, c(Surf). The I-E/ I-M value of PyMeA.HCl firstly increases and then decreases to 0 with c(Surf), showing a maximum on every curve. The critical aggregation concentration of the mixed surfactants determined from the I-E/ I-M maximum decreased from 5x10(-5) to 1x10(-5) mol/l as Y increased from 0.1 to 0.50, and then leveled off as Y increased up to unity. And at least 5x10(-6) mol/l CTAB was required for the mixed surfactants to bind on the PAMPS cooperatively. Equimolar binding of CTAB on AMPS was formed at I-E/ I-M=0 when Y greater than or equal to0.25, while at Y =0.1 some CTAB molecules in the mixed micelle were directed to the water phase without binding with AMPS. Both the intramolecular and the intermolecular NRET increased and then decreased with c(Surf), having a maximum on each curve corresponding to the equimolar binding of CTAB and AMPS so long as Y >0, indicating the coiling of the chain and interchain aggregation upon bound surfactants. The I-Py/ I-Np value at the maximum decreased with decreasing Y because more nonionic surfactant C12E8 participated into the polyelectrolyte-mixed surfactant complexes together with bound CTAB.
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Record 25 of 70
Author(s): Lu, L; Liu, XX; Qian, LY; Tong, Z
Title: Sol-gel transition in aqueous alginate solutions induced by cupric cations observed with viscoelasticity
Source: POLYMER JOURNAL, 35 (10): 804-809 2003
Abstract: Sol-Gel transition was occurred in 2 wt% aqueous solutions of four alginate samples with different molecular weight M-w and the ratio M/G of repeat unit mannuronate (M) to guluronate (G) induced by adding cupric ions. The transition was monitored with dynamic moduli G' and G" in the linear region of viscoelasticity and the gel point was determined according to the Winter's criterion where the loss angle tan (5 became independent of frequency omega. The mole ratio of Cu2+ to the carboxyl group in alginate at gel point, f(gel), was higher for the samples with lower molecular weight than those with higher molecular weight without obvious M/G dependence. This suggested there was no M/G selection of Cu2+ complex formation with alginate. The relaxation critical exponent n for alginate samples with higher G content was lower than 0.5, meaning G' > G" for the critical gels with a denser network. The cupric ion number relevant to one alginate chain at the gel point, N-gel, was estimated from f(gel) M-n/M-0 and reflected the gel elasticity.
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Record 26 of 70
Author(s): Sun, QL; Wang, CY; Ren, BY; Liu, XX; Zeng, F; Liu, P; Tong, Z
Title: Effects of added salts on intra- and inter-molecular fluorescence NRET of sulfonate polyelectrolytes
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 24 (9): 1695-1699 SEP 10 2003
Abstract: Naphthalene and pyrene singly and doubly labeled polyelectrolytes were prepared by radical copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) from 5% to 99% (molar fraction) and N, N-dimethylacrylamide with the label monomers. Fluorescence nonradiative energy transfer (NRET) was measured in NaCl and CaCl2 aqueous solutions up to the concentration of 6 X 10(-3) mol/L. Intra- and inter-molecular NRET determined with doubly labeled samples and mixtures of singly labeled samples indicated that owing to the salt screening effect, increasing salt concentration enhanced the NRET and the enhancement of calcium cation was stronger than that of sodium cation. The normalized NRET E-n, defined as the NRET in salt solution relative to that in water for a given sample, showed that intramolecular E-n decreased with the increase of charge density F-AMPS in the samples with a maximum at F-AMPS approximate to 0.45. In contrast, the intermolecular E-n increased with the increase of F-AMPS, suggesting that there were inhomogeneous intermolecular aggregates in polyelectrolyte solutions due to the condensed counterions even at a concentrations lower than the overlap threshold c*.
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Record 27 of 70
Author(s): Liu, XX; Qian, LY; Shu, T; Lu, L; Tong, Z
Title: Sol-gel transition and gel point determination for aqueous solutions of sodium alginate
Source: ACTA POLYMERICA SINICA, (4): 484-488 AUG 2003
Abstract: The aqueous solutions of 4 sodium alginate samples with different molecular weights, molecular weight distributions and M/G ratios were characterized with GPC, elemental analysis, and H-1-NMR. The sol-gel transition was determined by monitoring the dynamic moduli of these solutions with increasing their concentration within the linear viscoelasticity region at 25 degreesC. This transition was found to obey the Winter and Chambon's relaxation modulus equation G(t). From the independency of tandelta on frequency omega, the concentration of the gel point c(gel) and the critical exponent for the sol-gel transition n were estimated. For all samples c(gel) is 7.6wt% similar to 8.0wt%, almost independent of molecular weight M-w, and n equals 0.32 similar to 0.38 for three samples with higher M-w and 0.61 for the sample with lower M-w. This finding indicates that physical gelation in aqueous solutions of sodium alginate is mainly induced by the interaction between repeat units of the macromolecules, and that the longer chains contribute more perfect crosslinking structure at the gel point.
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Record 28 of 70
Author(s): Sun, QL; Wang, CY; Ren, BY; Tong, Z; Liu, XX; Zeng, F; Liu, P
Title: Conformation of polyelectrolyte chains with sulfonate groups observed with fluorescent nonradiative energy transfer
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 24 (7): 1302-1306 JUL 2003
Abstract: Strong polyelectrolytes were prepared by copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) from 5% to 99%(charge densities) with N,N-dimethylacrylamide and lightly labeled by naphthalene and pyrene, respectively. The overlap mass concentration p* determined by intermolecular nonradiative energy transfer(NRET) decreased from 0.55 to 0.25 g/L with increasing the charge density of the samples and was about one order of magnitude smaller than that determined from the relative excimer emission. With increasing the charge density in dilute aqueous solution, the intermolecular NRET was first weakened till the charge density of about 30% and then enhanced. This phenomenon can be qualitatively interpreted in the framework of Manning's theory for counterion. condensation and tion of highly charged polyelectrolytes.
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Record 29 of 70
Author(s): Liu, P; Zhou, XP; Hu, JH; Zhao, QZ; Deng, WJ; Tong, Z; Xu, YH; Wan, MX
Title: Synthesis and liquid crystal properties of a novel class of oligothiophene derivatives
Source: ACTA CHIMICA SINICA, 61 (5): 774-779 MAY 2003
Abstract: With the aim of developing new oligothiophene-based liquid crystals involving hydrogen bonding, new terthiophene derivative's containing an alkylamide group, N,N'-dialkyl-5,5"-dibromo-2,2': 5', 2"-terthiophene-4,4"-dicarboxamide (DNC(n)DBr3T, n = 5, 8, 16, 18), were designed and synthesized, and their thermal behaviors were examined. While DNC(n)DBr3T compounds with n 16, 18 were found to form smectic A phase, DNC(5)DBr3T did not form liquid crystal phase. In addition to liquid crystal behavior, crystal polymorphism was also observed for DNC(16)DBr3T. It is shown that the alkyl chain length greatly affects liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding plays a role in the formation of liquid crystal phase in the DNC(n)DBr3T system.
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Record 30 of 70
Author(s): Sun, QL; Ren, BY; Liu, XX; Zeng, F; Liu, P; Tong, Z
Title: Fluorescence study for the electrostatic interaction and aggregation in dilute polar solution of polyelectrolytes
Source: MACROMOLECULAR SYMPOSIA, 192: 251-264 MAR 2003
Abstract: Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethylacryl-amide (DMAA) were observed in dilute salt-free aqueous solutions as a function of the mole fraction F-AMPS of AMPS from 0 to 0.896. Monoexponential and biexponential decays were found for the samples of F-AMPS < 0.35 and samples of F-AMPS > 0.35, respectively. The fast decay component is 80% and the averaged lifetime
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Record 31 of 70
Author(s): Sun, QL; Tong, Z; Wang, CY; Liu, XX; Zeng, F
Title: Fluorescence decay and quenching of pyrene labeled on sulfonate polyelectrolytes in salt-free aqueous solutions
Source: EUROPEAN POLYMER JOURNAL, 39 (4): 697-703 APR 2003
Abstract: Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N, N-dimethylacrylamide were observed in dilute salt-free aqueous solutions as a function of the mole fraction F-AMPS of AMPS from 0 to 0.896. Monoexponential decay was found for the samples of FAmps < 0.35 and biexponential decay for the samples of F-AMPS > 0.35. The fast decay component is 80%, and the averaged lifetime (T) and lifetime T, of the fast decay is decreased with increasing FAmps. Quenching efficiency of Cu2+, I-, CH3NO2, and dinitrobenzene to the pyrene label was investigated in the framework of Stern-Volmer plot. With increasing FAmps the quenching efficiency of Cu2+ is increased while that of I- decreased. For the neutral quenchers, the quenching rate constant k(q) increases when F-AMPS < 0.449 then decreases, showing a decline of accessibility to the pyrene label. These results were interpreted consistently with the counterion condensation concept, where condensed counterions caused the polyelectrolyte chains to aggregate. The existence of less-polar "temporal aggregated domain" in highly charged polyelectrolytes appears to lead to the slower decay and lower accessibility of the pyrene labels. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Record 32 of 70
Author(s): Guo, YQ; Tong, Z; Chen, MC; Liang, XH
Title: Solution miscibility and phase-change behavior of a polyethylene glycol-diacetate cellulose composite
Source: JOURNAL OF APPLIED POLYMER SCIENCE, 88 (3): 652-658 APR 18 2003
Abstract: Polyethylene glycol (PEG) and diacetate cellulose (CDA) exhibit good miscibility in acetone solution. The miscibility is related to the molecular weight of PEG, which increases as miscibility decreases. The phase-change behavior of PEG in composite with CDA prepared from the miscible solution was found to be completely different from that of pure PEG. When the PEG fraction in the composites was less than 85%, PEG within the composite did not melt into liquid; even when the temperature was 40degreesC higher than the melting point of PEG, the PEG-CDA composite exhibited solid-solid phase-change behavior. Thermal analysis indicated that the PEG-CDA composite had greater enthalpy and exhibited good thermal stability. The PEG-CDA composite that exhibited solid-solid phase-change behavior can be used as a new kind of phase-change material for thermal energy storage and temperature control. (C) 2003 Wiley Periodicals, Inc.
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Record 33 of 70
Author(s): Liu, XX; Qian, LY; Shu, T; Tong, Z
Title: Rheology characterization of sol-gel transition in aqueous alginate solutions induced by calcium cations through in situ release
Source: POLYMER, 44 (2): 407-412 JAN 2003
Abstract: Four alginate gels were prepared by in situ release of calcium cations from Ca-EDTA with gradual hydrolysis Of D-glucono-delta-lactone (GDL) in 3 wt% of aqueous solutions of four alginate samples with different M/G compositions, molecular weights, and molecular weight distributions. The sol-gel transition was monitored by measuring the dynamic mechanical spectroscopy in the linear region with variation in the mole ratio f of Ca2+ to the carboxyl group in the alginate. f(gel), the critical value off at the gel point, was determined according to the appearance of power law relaxation for the storage and loss moduli as proposed by Winter and Chambon. The critical exponent of relaxation moduli n for the power law was estimated from the loss tangent tan delta = G(II)/G(I) at the gel point which is independent of angular frequency. f(gel) for the two samples with higher M/G ratio is about 0.037 while that for the other two samples with lower M/G ratio is 0.049 and 0.060, suggesting that more Ca2+ cations are chelated into the 'egg-box' cavities formed by the G sequence to cross-link alginate chains with higher G content. The n value is higher than 0.5, showing that the Ca2+ induced alginate network is not perfect due to its low concentration. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Record 34 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Simulation for binding equilibrium of ionic derivative of pyrene with polyelectrolyte
Source: ACTA POLYMERICA SINICA, (6): 729-733 DEC 2002
Abstract: Binding of cationic derivative of pyrene, pyrenemethylamine hydrochloride (PyMeA.HCl) to a polyanion, poly (2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in aqueous solutions was probed by the excimer fluorescence and simulated with a competitive binding equilibrium model. The relative emission intensity I-E/I-M of excimer to monomer displays a maximum with increasing PyMeA.HCl concentration and the binding stoichiometry for saturation binding is determined from the concentrations of PAMPS and PyMeA.HCl at the maximum. I-E/I-M obviously decreases with adding sodium chloride of about 10(-4) mol/L into the solution due to the. competitive binding of sodium and probe cations. In our binding equilibrium model; the binding of different cations on anionic polymer is considered as an equilibrated reversible process governed by the equilibrium constant. I-E and I-M are assumed to be proportional to the probe concentrations forming excimer and remaining individually, respectively. Calculated bound probe concentration c(DL) increases with total probe concentration c(DO) before binding saturation and the increasing rate becomes higher with higher value of the equilibrium constant. The simulated I-E/I-M as the above probe concentration ratio, also shows a maximum with increasing c(DO) at the same position as experimentally observed. By assuming. a comparable binding equilibrium constant for the cation of added salt, the, abrupt decrease in I-E/I-M observed with adding salt is reproduced by the simulation.. These results, indicate that the competitive binding of ionic pyrene probe on polyelectrolyte can be reasonably described by the binding equilibrium model.
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Record 35 of 70
Author(s): Zeng, F; Sun, ZW; Wang, CY; Ren, BY; Liu, XX; Tong, Z
Title: Fabrication of inverse opal via ordered highly charged colloidal spheres
Source: LANGMUIR, 18 (24): 9116-9120 NOV 26 2002
Abstract: A new and simple procedure for producing highly ordered three-dimensional colloidal crystalline template was developed, which employs latexes containing highly charged polystyrene spheres. The water on the surface of the latex was evaporated, causing the formation of close-packed colloidal crystals on the surface. The driving forces for the formation of close-packed crystal involve electrostatic interaction and lateral capillary force, and the ion diffusion during the evaporation is considered to be an important factor for the successful assembly of ordered structure on the latex surface. Then the sol-gel solution was infiltrated into the interstitial space of the prepared colloidal crystals through capillary effect, and ordered inverse opals were obtained by calcining the polystyrene beads. The inverse opal thus prepared has long-range ordering with its defect-free area extending to over 10 micrometers and covering thousands of pores.
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Record 36 of 70
Author(s): Wang, CY; Tong, Z; Zeng, F; Ren, BY; Liu, XX
Title: Fluorescence study of chromophore labeled strong polyelectrolyte bound with oppositely charged surfactant
Source: COLLOID AND POLYMER SCIENCE, 280 (9): 814-821 SEP 2002
Abstract: Four strong polyelectrolyte samples of 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) and N,N-dimethylacrylamide (DMAA) were radically copolymerized with a single label of naphthalene or pyrene, with both labels and without label. containing, about 40 mol % AMPS. Fluorescence nonradiative energy transfer (NRET) IPy/INp, anisotropy r, I-1/I-3 and excimer emission I-E/I-M, of pyrene labels were observed in dilute aqueous solutions with and without cationic surfactant of cetyltrimethylammonium bromide (CTAB). The overlap concentration as determined as 3 g L from the appearance of intermolecular excimer. The variation of intra- and intermolecular NRET with total polyelectrolyte concentration showed that the charged chains preferentially interpenetrated each other rather than reduce their coil volume as their concentration beyond the overlap threshold. By binding with CTAB, the polyelectrolyte chain became more coiled as known from the reduced viscosity. The intramolecular NRET was dominant when [CTAB] less than or equal to 4x10(5) M and then the intermolecular NRET occurred at higher CTAB concentrations with hydrophobic aggregation between CTAB tails bound on different polyelectrolyte chains. The CTAB concentration corresponding to the maxima of I-Py/I-Np just is equal to the AMPS monomer concentration, indicating, the formation of 1:1 binding between surfactant and polyelectrolyte in very dilute solutions. Added salt of NaCl up to 0.1 M hardly affected the intramolecular NRET but affected the I-Py/I-Np value for the intermolecular NRET.
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Record 37 of 70
Author(s): Liu, P; Tong, Z; Deng, WJ
Title: Synthesis and gel-forming properties of a novel class or oligothiophene derivatives
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 23 (8): 1632-1637 AUG 2002
Abstract: In order to develop a novel class of low molecular-weight organic gels and to gain an insight into the relationship between molecular structure of gel-forming compounds and gel-forming properties, a novel family of low molecular-weight organic compounds containing terthiophene and tetrathiophene, N,N'-distearyl-5,5"-(2,2' : 5' 2"-torthiophene)dicarboxamide(DNC(n)DOc3T), N,N'-dialkyl-5,5"-(3,3"-dioctyl-2, 2' : 5' 2"-terthiophene) dicarboxamidc (DNC(n)DOc3T, n = 5, 8, 16, 18) and N, N'-distearyl-5, 5"-(3, 3"-dioctyl-2,2' - 5', 2" : 5" 2"-tetrathiophene) dicarboxamide (DNC(18)DOc4T), were designed and synthesized. Whereas DNC(18)3T and DNC(5)DOc3T did not form gels with organic solvents, DNC(n)DOc3T(n =8, 16, 18) and DNCgDOc4T were found to form gels with certain organic solvents. These are the first examples of low molecular-weight organic gels containing an oligothiophone moiety. It is of interest to note that while DNC(8)DOc3T forms opaque gels with alcohols, such as ethanol and isopropanol, DNC(16)DOc3T, DNC(18)DOc3T and DNC(18)DOc4T formed transparent gels with hydrocarbon solvents such as heptane, octane undecane and others. It is shown that the intermolecular hydrogen bonding and intermolecular interaction between the long alkyl chain in the N-alkylcarboxamide group as well as the incorporation of an alkyl group at the P-position of the thiophene ring play an important role for the formation of gels. The xerogel showed three-dimensional networks of fibrous bundle structure. DNC(18)DOc3T/benzonitrile gel and DNC(18)DOc4T/benzonitrile gel were found to function as a new type of electrochromic materials, exhibiting a reversible color changes on electrochemical oxidation and reduction.
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Record 38 of 70
Author(s): Zeng, F; Sun, ZW; Wu, SZ; Liu, XX; Wang, ZY; Tong, Z
Title: Preparation of highly charged, monodisperse nanospheres
Source: MACROMOLECULAR CHEMISTRY AND PHYSICS, 203 (4): 673-677 MAR 15 2002
Abstract: A two stage shot growth emulsifier-free polymerization was applied to prepare styrene(St)/sodium styrenesulfonate (NaSS) latices. The latex particles prepared in the pure water medium were monodisperse and highly charged spheres, but their particle diameters were all higher than 120 nm. By using the two-stage shot growth copolymerization at 70 degreesC in the mixed reaction medium of water and acetone, we successfully prepared monodisperse, highly charged nanospheres with the smallest particle diameter of 89 nm. As the acetone content in the mixed reaction medium was increased to an acetone/H2O ratio of around 0.125, the particle diameter decreased to minimum, and then the particle diameters increased with increasing acetone content in the mixed reaction medium. The conversion-time curves for the first stage emulsifier-free copolymerization of St/NaSS in the mixed reaction medium with varied acetone contents show that the polymerization rate first increased with increasing acetone content, and then decreased. The enhanced rate of polymerization in the lower acetone content results from the increase in the number of primary particle in the reaction medium. As the acetone content was further increased, the solubility of St in the reaction medium further increased, making the copolymerization somewhat like the dispersion polymerization and thus causing increased particle size.
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Record 39 of 70
Author(s): Liu, P; Liang, D; Tong, Z; Liu, XX
Title: Synthesis and luminescence properties of novel europium and terbium complexes with triblock copolymer ligand
Source: MACROMOLECULES, 35 (5): 1487-1488 FEB 26 2002
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Record 40 of 70
Author(s): Wu, SZ; Zeng, F; Li, FX; Tong, Z
Title: Phase stability of the photoconductive polysiloxane-based photorefractive composites
Source: POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, 40 (5): 627-634 2001
Abstract: This article discusses the phase stability of the photoconductive poly siloxane-based photorefractive composites as studied by the light-scattering method. The photorefractive properties of the composites were studied by the two-beam coupling technique. The effects of the electric field on the photorefractive property of the composites were investigated as well. The phase stability was found to be dependent on the chromophore concentration and storage temperature. The two-beam coupling gain coefficient of the composites increased with increasing electric field and chromophore content.
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Record 41 of 70
Author(s): Liu, P; Tong, Z
Title: A novel greenish blue-emitting amorphous molecular material: 2,5-bis{4-[2-naphthyl(phenyl)amino]phenyl}thiophene
Source: CHINESE JOURNAL OF CHEMISTRY, 19 (10): 979-982 OCT 2001
Abstract: A novel greenish blue-emitting amorphous molecular material, 2,5-bis {4-[2-naphthyl(phenyl) amino] phenyl}thiophene (BN-pA-1T), was designed and synthesized. Its molecular properties, glass-forming property, and application to an organic EL device were investigated.
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Record 42 of 70
Author(s): Wang, CY; Sun, QL; Tong, Z; Liu, XX; Zeng, F; Gao, F
Title: Binding of ionic derivative of pyrene to strong polyelectrolyte
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 22 (7): 1265-1267 JUL 2001
Abstract: Binding of pyrene probe cation of 1-pyrenemethylamine hydrochloride (PyMeAH(+)) to sulfonate polyelectrolyte PAMPS in aqueous solution was investigated by the relative fluorescent intensity I-E/I-M of the excimer to monomer. The saturation amount of repeat unit AMPS for the polyelectrolyte bound to one PyMeAH(+) ion was about 2.5 estimated from the maximum on the curve of I-E/I-M vs. the probe concentrations. The increase of the ionic strength of the solution by adding salt or excess alkali ions of 10(-4) mol/L greatly reduced the I-E/I-M value. This fact suggested that the probe cation PyMeAH+ form a loose ion pair with the sulfonate anion on the polyelectrolyte.
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Record 43 of 70
Author(s): Wang, C; Sun, Q; Tong, Z; Liu, X; Zeng, F; Wu, S
Title: Interaction of cetyltrimethylammonium bromide and poly(2-(acrylamido)-2-methyl-propanesulfonic acid) in aqueous solutions determined by excimer fluorescence
Source: COLLOID AND POLYMER SCIENCE, 279 (7): 664-670 JUL 2001
Abstract: The binding interaction of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic poly(2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in dilute aqueous solutions was studied using the excimer fluorescent emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA . HCl). In the absence of CTAB, the saturation binding of PyMeAH(+) on PAMPS is about 2.4 AMPS repeat units for one probe cation as determined by the relative emission intensity, I-E/I-M, of the excimer to monomer. With increasing CTAB concentration, I-E/ I-M firstly increases, reaches a maximum, then decreases to zero. The I-E/I-M maximum indicates a critical aggregation concentration (cac) of 10(-5) mol/l for CTAB in PAMPS solutions. The CTAB concentration at which I-E/I-M is zero is exactly equal to the PAMPS concentration, indicating that the probe cation is thoroughly excluded from the binding site of PAMPS by the CTAB cation and the equivalent stoichiometric aggregation is formed between CTAB and PAMPS. The blueshift of the excimer emission and the excitation spectra shows that the decrease of I-E/I-M with increasing CTAB concentration above the cac is caused mainly by the decrease of the static excimer.
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Record 44 of 70
Author(s): Yang, YY; Zeng, F; Xie, XL; Tong, Z; Liu, XX
Title: Phase separation and network formation in poly(vinyl methyl ether)/water solutions
Source: POLYMER JOURNAL, 33 (5): 399-403 2001
Abstract: Cloud point temperature T-clo and dynamic moduli were measured on aqueous solutions of two poly(vinyl methyl ether) (PVME) samples with molecular weight of 1.16 X 10(4) and 2.57 X 10(4), respectively and M-w/M-n = 1.84 for both samples. The T,I, at which the solution becomes turbid is at around 32.5 degreesC without obvious molecular weight dependence due to their broad molecular weight distribution. The frequency omega dependence of the storage modulus G' and loss modulus G" observed within linear viscoelasticity region indicates that the PVME/water solution exhibits homogeneous fluid behavior at 25 degreesC below T-clo, while shows a plateau zone for G' at 34 degreesC above T-clo, suggesting the appearance of network structure at this temperature. A sharp increase in G' and G" was observed at about 32.5 degreesC with increasing temperature of a PVME/water solution, indicating that at this temperature the network begin to form. These results imply that the network structure is formed accompanying the phase separation in PVME/water solutions due to the hydrophobic bonding between polymer chains.
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Record 45 of 70
Author(s): Ren, BY; Tong, Z; Gao, F; Liu, XX; Zeng, F
Title: Fluorescence and X-ray diffraction studies on binding and complexes of surfactants and dansylated polyelectrolytes with sulfonate groups
Source: POLYMER, 42 (17): 7291-7298 AUG 2001
Abstract: Binding of cationic surfactant cetyltrimethylammonium bromide (CTAB) on polyelectrolytes ADDan containing different amounts of sulfonate groups was studied by fluorescence spectrum of dansyl labels in aqueous solution. With increasing concentration of CTAB, there was an abrupt drop in the emission maximum wavelength lambda (em) and a sharp increase in the relative intensity RF defined as the ratio of emission in the presence of CTAB to that without CTAB. The critical aggregation concentration (cac) determined from the former was about 3 x 10(-5) mol/l without obvious dependence on polymer charge density. Solid complex films of polyelectrolyte-surfactant of CTAB or dodecyltrimethylammonium chloride (DTAC) were obtained by precipitation and their fluorescence anisotropy r indicated a high mobility of the dansyl chromophore. The r-value for ADDan-CTAB complexes obviously decreased as the charge density of the polyelectrolyte increased while the r for ADDan-DTAC complexes was slight decline, suggesting the contribution of alkyl tails of the surfactant to local mobility. It was the first time to find that the higher the charge density of the polyelectrolyte, the less polar the micellar aggregation of polyelectrolyte-surfactant complex becomes in dilute aqueous solution, which remains in the solid complex. SAXS of the solid complexes illustrated a long-range ordered lamella structure with the long period d of 3.87 and 3.04 nm for CTAB and DTAC complexes, respectively. (C) 2001 Published by Elsevier Science Ltd.
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Record 46 of 70
Author(s): Yang, YY; Zeng, F; Tong, Z; Liu, XX; Wu, SZ
Title: Phase separation in poly(N-isopropyl acrylamide)/water solutions. II. Salt effects on cloud-point curves and gelation
Source: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 39 (9): 901-907 MAY 1 2001
Abstract: The cloud-point temperatures (T-clo's) of poly(N-isopropyl acrylamide) (PNI-PAM)/water solutions with NaCl, NaBr, or NaI were measured. All these salts reduced the T-clo's of PNIPAM/water solutions to different extents, in the following order: NaCl > NaBr > NaI. The higher the concentration of the added salt was, the more greatly T-clo dropped. A dynamic viscoelasticity investigation of the PNIPAM/water solutions with the salts indicated that during phase separation, the system changed from a homogeneous fluid into a physically crosslinked network, and the addition of salts also reduced the temperature at which this change began. The gelation temperature (T-gel,) and the scaling exponent of the PNIPAM/water solutions with NaBr were obtained with dynamic scaling theory, and T-gel was found to be close to T-clo. That the addition of salts to the solution decreased T-clo and T-gel to the same extent further proved that the network structure was formed with the phase separation in the PNIPAM/water solutions. (C) 2001 John Wiley & Sons, Inc.
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Record 47 of 70
Author(s): Zeng, F; Wu, SZ; Li, FX; Tong, Z
Title: Temperature dependence of the photorefractive property of PMMA-based composite
Source: EUROPEAN POLYMER JOURNAL, 37 (3): 459-462 MAR 2001
Abstract: Temperature dependence of the photorefractive (PR) property of poly(methyl methacrylate) (PMMA)-based polymer composite is presented. The electrooptic and PR properties of PMMA-based polymer composite have been studied in the temperature range of 22-60 degreesC. The effects of electric field on the PR property of the material have been investigated as well. The experimental results show that the electrooptic coefficient first increases slightly with the enhancing temperature and eventually saturates. This behavior is attributed to the temperature activated orientational mobility of the second-order nonlinear chromophores. Diffraction efficiency first increases with the increasing temperature, and then decreases as the temperature is further enhanced; while the diffraction efficiency increases with the increasing field strength. (C) 2001 Elsevier Science Ltd. All rights reserved.
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Record 48 of 70
Author(s): Ren, BY; Tong, Z; Gao, F; Liu, XX; Zeng, F
Title: Charge density effects on the fluorescence behavior of dansyl labels to strong polyelectrolytes
Source: POLYMER, 42 (5): 2001-2006 MAR 2001
Abstract: Fluorescent spectra of dansyl-labeled copolymers containing 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethyl-acrylamide (DMAA) with 0.2 mol% chromophore were observed in aqueous solution. Two emission bands appeared at 336 and 533 nm for protonated and unprotonated species of the label, respectively. These wavelengths were independent of the mole fraction F-AMPS of AMPS ranging from 0.186 to 0.738 but the relative intensity I-336/I-533 increased proportionally to F-AMPS. The locally excited emission (LE), b* band of the dansyl label was found at. 405 nm when the chromophore concentration was decreased below 1.45 x 10(-5) mol/l. With increasing charge density in the solid copolymer the b* band was strengthened and the a* band for the twisted intramolecular charge-transfer state was weakened and even disappeared owing to the existence of ion-pair attractions. It was found that for the copolymer in dimethyl sulfoxide (DMSO)/tetrahydrofuran (THF) mixtures the change in charge density did not alter the emission wavelength lambda (em) of the a* band. The charge density dependence fur the threshold of DMSO/THF composition, at which the relative emission intensity RF abruptly decreased, was similar to that inducing the volume phase transition in the corresponding polyelectrolyte gels. (C) 2000 Elsevier Science Ltd. All rights reserved.
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Record 49 of 70
Author(s): Tong, Z; Ren, BY; Gao, F
Title: Dual behavior of polyelectrolyte and ionomer for an ionizable polymer containing sulfonate groups in DMSO/THF mixtures
Source: POLYMER, 42 (1): 143-149 JAN 2001
Abstract: A dansyl labeled polyelectrolyte (ADDan60) was prepared by copolymerization of ionizable monomer 2-(acrylamido)-2-methylpropanesulphonic acid (AMPS) with N,N-dimethylacrylamide (DMAA) and N-[2-[[[5-(N,N-dimethylamino)-1-naphthalenyl]-sulfonyl]amino]ethyl]-2-propenamide (DANSAEP, 0.2 mol%). Reduced viscosity eta(sp)/c, electrolytic conductivity kappa, and fluorescent spectrum of ADDan60 in DMSO/THF mixtures were measured as functions of the volume fraction V-THF Of THF. In the region of V-THF < 0.7, the emission maximum lambda(em), relative intensity R-F of ADDan60 in DMSO/THF to that in DMSO, and anisotropy ratio r indicated that the polymer maintained its solvation layer not to change so much as the bulk solvent and exhibited a polyelectrolyte behavior, as observed from eta(sp)/c and kappa. Once V-THF was beyond 0.70, the solvation layer was changed leading to the ion pair formation in an avalanche manner, which induced chain aggregation and phase transition due to the dipole attraction. The results suggest a behavior transition in ionizable polymers from polyelectrolyte into ionomer induced by medium polarity. (C) 2000 Elsevier Science Ltd. All rights reserved.
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Record 50 of 70
Author(s): Zeng, F; Liu, XX; Tong, Z; Yang, YY; Wu, SZ
Title: Thermal reversible gelation during phase separation of poly(N-isopropyl acrylamide)/water solution
Source: SCIENCE IN CHINA SERIES B-CHEMISTRY, 43 (4): 428-434 AUG 2000
Abstract: By dynamic viscoelastic measurement for PNIPAM/water solution it has been found that below the phase separation temperature (about 32 degrees C), the system is homogeneous fluid; while upon being heated to about 32 degrees C, the solution undergoes phase separation and the storage modulus G' increases sharply and exceeds the loss modulus G", indicating the physical network formation during the phase separation. Based on the percolation model, the gel points T-gel were obtained by applying the dynamic seating theory (DST) and Winter's criterion. The critical exponent n was also obtained to be 0.79 through DST, which is different from 0.67, the critical point of chemically crosslinked network predicted through DST. The obtained n value reflects the special property of physical network being different from chemical network.
Record 51 of 70
Author(s): Gao, F; Yan, Y; Ren, BY; Tong, Z
Title: Fluorescence spectra of pyrene labeled polyelectrolytes with sulfonate groups in water and DMSO
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 21 (6): 976-979 JUN 2000
Abstract: 1-Pyrenylmethyl-methacrylamide (PyMA) was synthesized, and applied to copolymerizing with AMPS and DMAA to get a series of pyrene labeled polymers with sulfonate groups. The molar fraction of sulfonate monomer AMPS in these samples varies from 0. 032 6 to 0. 896. In DMSO and water, the profile of fluorescence spectrum of pyrene labeled polyelectrolytes is analogous to that of PyMA when F-AMPS < 0. 449, while the [0,1] emission peak abruptly increased as F-AMPS greater than or equal to 0. 449, The so-called polarity scale of pyrene, I-1/I-3 Of pyrene labeled polyelectrolytes in DMSO and in water decreases gradually with increasing FAMPS representing the charge density of the samples. I-1/I-3 also decreases gradually with the increase in polymer concentration in water. The results imply that there exists the hydrophobic aggregation through locally electrostatic attraction even in polyelectrolyte/polar solvent system, in contrast to the traditional polyelectrolyte theory. However, I-1/I-3 Of these polyelectrolytes remains almost a constant with increasing NaCl concentration of aqueous solution up to 0. 75 mol/L, indicating the electrostatic attraction cannot be simply screened.
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Record 52 of 70
Author(s): Gao, F; Ren, BY; Yan, Y; Tong, Z
Title: Changes in solvation state of strong polyelectrolytes in DMSO/THF mixtures
Source: ACTA PHYSICO-CHIMICA SINICA, 16 (5): 450-453 MAY 2000
Abstract: The fluorescent spectra of two series of sulfonated polyelectrolytes respectively labeled with dansyl and pyrenyl groups were determined as a function of volume fraction phi(THF) of THF in DMSO/THF mixed solvents. When phi(THF) less than or equal to 0.65, the maximum wavelength lambda(em) and the intensity RF relative to that in DMSO for a* band of dansylated samples, as well as I-1/I-3 for pyrene labeled samples varied slightly with increasing (phi(THF), indicating the capability of polyelectrolyte to maintain its chain solvation stable. As long as phi(THF) beyond 0.70, there was an abrupt drop in R-F and lambda(em) showing the sudden change in the chain solvation layer. I-1/I-3 decreased with an increase in the charge density of polyelectrolyte samples, suggesting the existence of aggregated structure even in pure DMSO.
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Record 53 of 70
Author(s): Tong, Z; Zeng, F; Zheng, X; Sato, T
Title: Inverse molecular weight dependence of cloud points for aqueous poly(N-isopropylacrylamide) solutions
Source: MACROMOLECULES, 32 (13): 4488-4490 JUN 29 1999
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Record 54 of 70
Author(s): Ren, BY; Gao, F; Tong, Z; Yan, Y
Title: Solvent polarity scale on the fluorescence spectra of a dansyl monomer copolymerizable in aqueous media
Source: CHEMICAL PHYSICS LETTERS, 307 (1-2): 55-61 JUN 25 1999
Abstract: A copolymerizable fluorescent monomer N-[2-[[[5 -(N,N-dimethylamino)-1-naphthalenyl] sulfonyl]-amino]ethyl]-2-propenamide (DANSAEP) was synthesized, which exhibits dual fluorescence due to the twisted intramolecular charge transfer in the excited state. The emission maximum lambda(em) shifts from 463.3 nm in n-hexane to 530.0 nm in water, showing solvent polarity dependence. The relations between lambda(em) and the conventional solvent polarity parameters E-T(30) or Z are linear, dividing solvents into protic and aprotic groups. Kamlet's linear solvation energy relationship gives a good description for lambda(em) as a solvent polarity scale. The increment of dipole moment Delta mu at the excited state was estimated as 5.09 D with the solvatochromic analysis. (C) 1999 Elsevier Science B.V. All rights reserved.
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Record 55 of 70
Author(s): Zeng, F; Tong, Z; Sato, T
Title: Molecular chain properties of poly( N-isopropyl acrylamide)
Source: SCIENCE IN CHINA SERIES B-CHEMISTRY, 42 (3): 290-297 JUN 1999
Abstract: A series of poly( N-isopropyl acrylamide) (PNIPAM) samples with molecular weight ranging from 2.23 x 10(4) to 130 x 10(4) and molecular weight distribution M-w/M-n less than or equal to 1.28 were obtained by free radical polymerization and repeat precipitation fractionation. The molecular weight M-w, second virial coefficient A(2) as well as the mean-square-root radius of gyration [S-2] for PNIPAM samples in tetrahydrofuran (THF) were determined by light scattering, and the relations were estimated at A(2) proportional to M-w(-0.25) and [S-2](1/2) = 1.56 x 10(-9) M-w(0.56). The intrinsic viscosity for THF: solution and methanol solution of PNIPAM samples was measured and the Mark-Houwink equations were obtained as [ eta] = 6.90 x 10(-5) M-0.73 (THF solution) and [eta] = 1.07 x 10(-4) M-0.71 (methanol solution). The above results indicate that both THF and methanol are good solvents for PNIPAM. The limit characteristic ratio C-infinity for PNIPAM in the two solutions was determined to be 10.6 by using Kurata-Stockmayer equation, indicating that the flexibility of PNIPAM chain is close to that of polystyrene. The intrinsic viscosity for the aqueous solution of PNIPAM was measured at 25-30.5 degrees C. The result demonstrates that PNIPAM chain begins to shrink at 25 degrees C, and from about 30 degrees C onward the molecular chain shrinks much more sharply till the solution becomes macroscopically unstable at 32 degrees C.
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Record 56 of 70
Author(s): Liu, XX; Tong, Z; Gao, F
Title: Novel shrinking-swelling hysteresis in DMSO/THF mixtures of copolymer gels containing sulphonate groups
Source: POLYMER INTERNATIONAL, 47 (2): 215-220 OCT 1998
Abstract: The swelling volume of copolymer gels made from 2-(acrylamido)-2-methylpropanesulphonic acid (AMPS; electrolyte monomer), N,N-dimethylacrylamide (DMAA; comonomer) and N,N'-methylenebis(acrylamide) (BIS; crosslinker) was measured in mixtures of two organic solvents, dimethyl sulphoxide (DMSO) and tetrahydrofuran (THF) at 25 degrees C. A volume phase transition was observed in the gels having 43.18 mol% AMPS with different counterions K+, Na+ and H+, when the THF concentration in the mixture increased beyond a certain value. We observed a swelling-hysteresis between the shrinking and swelling curves, i.e. more DMSO was required to make a shrunk gel start to swell again than to cause the volume shrinking. This hysteresis stems from the formation of ion pairs and/or multiplets in the ionizable gels when the medium polarity is decreased. An excess of DMSO is required to reduce the ionization energy for making the shrunk gel swell again in the DMSO/THF mixture. These aggregates and multiplets do not seem to be entirely removed by the swelling process and act as additional physical crosslinks, so that the DMSO concentration required to induce the shrunk gel to swell becomes higher in the next swelling process, showing another hysteresis. The release of bound water from the solvating layer after shrinkage may be another possible reason for this hysteresis. (C) 1998 Society of Chemical Industry.
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Record 57 of 70
Author(s): Zheng, X; Tong, Z; Xie, XL; Zeng, F
Title: Phase separation in poly(N-isopropyl acrylamide) water solutions I. Cloud point curves and microgelation
Source: POLYMER JOURNAL, 30 (4): 284-288 1998
Abstract: Cloud point curve was determined on binary and ternary aqueous solutions of several fractionated poly(N-isopropyl acrylamide) (PNIPA) samples with the molecular weight M-eta = 11.3 x 10(4)-210 x 10(4) and the molecular weight distribution M-w/M-n = 1.21-1.62. In both the binary and ternary solutions, the cloud point temperature T-clo slightly increases viith the increase in molecular weight of PNIPA. The concentration dependence for the binary solution is weak while it becomes obvious for the ternary solution containing two different PNIPA samples in water; i.e., the molecular weight distribution alters the shape of the cloud point currie. The storage and loss moduli G' and G " for the PNIPA sample of M-eta = 210 x 10(4) in water at concentrations 2.2-8.5 wt% were measured at several temperatures encompassing the T-clo. The results indicate that the solution changes from a homogeneous fluid into viscoelastic microgels suspended in a liquid phase during the phase separation. This physical network is considered to be jointed via the intermolecular hydrophobic bonding between the N-isopropyl groups, which may provide a model system for the structure change or proteins induced in the denaturation.
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Record 58 of 70
Author(s): Liu, XX; Hu, O; Tong, Z; Gu, J
Title: Volume phase transition of copolymerized sulfonic acid gels in mixed organic solvents
Source: CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 19 (3): 460-463 MAR 1998
Abstract: Radical copolymerization of 2-acrylamido-2-methylpropane sulfonic acid(AMPS) with 2-hydropropyl methacrylate (HPM) was conducted in ethylene glycol/water (1:1 in weight) at 70 degrees C. The azeotropic composition was found at the monomer molar ratio of AMPS/HPM as 8/2, Three sulfonic gels were prepared at this composition with the crosslinker N,N'-methylene-bis(acrylamide) of 2%, 3% and 5% (molar percentage), and referred to as G02, G03 and G05, respectively, As expected from their polyelectrolyte nature, these gels swell in dimethyl sulfoxide(DMSO) but shrink in tetrahydrofuran(THF) at 25 degrees C, The volume phase transition takes place in the G02 and G03 swollen in DMSO/THF mixtures when THF content is increased beyond 55%similar to 60% (volume ratio), In ethanol/THF mixture, however, no volume phase transition was found though the gel still shrunk with increasing THF. The dipole-dipole interaction model in less-polar medium was adopted to interpret these results with the concept of preferential solvation.
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Record 59 of 70
Author(s): Zeng, F; Zheng, X; Tong, Z
Title: Network formation in poly(N-isopropyl acrylamide) water solutions during phase separation
Source: POLYMER, 39 (5): 1249-1251 MAR 1998
Abstract: Evidence from dynamic viscoelasticity measurements has been found for reversible network formation via the physical association of hydrophobic side-groups during phase separation at around 33 degrees C in a 1.22 wt.% aqueous solution of poly(hi-isopropyl acrylamide) (PNIPA) having a molecular weight of 2.1 x 10(6). The frequency omega dependence of the dynamic storage and loss moduli G' and G " showed homogeneous fluid behaviour at 25 degrees C, while at 35 degrees C, a plateau zone was found in the G' versus omega curve and G' was larger than G ", indicating the formation of a network. The increase in G' was instantaneous at the phase separation temperature and was not a progressive process. (C) 1997 Elsevier Science Ltd. All rights reserved.
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Record 60 of 70
Author(s): Zeng, F; Tong, Z; Yang, XZ
Title: Differences in vibrational spectra of poly(N-isopropyl acrylamide) from water solution before and after phase separation
Source: EUROPEAN POLYMER JOURNAL, 33 (9): 1553-1556 SEP 1997
Abstract: Two poly(N-isopropyl acrylamide) (PNIPA) samples were prepared by drying the 5 wt% water solution of PNIPA either at 25 degrees C without phase separation (referred to as I-B) or at 38 degrees C after phase separation (I-C). PNIPA sample I-A was directly cast from its acetone solution. The IR absorbance of CH3 asymmetric stretch related to the CH2 symmetric stretch is higher for the samples I-C and I-A when compared with the same absorbance ratio for the sample I-B. At the same time, the vibration frequencies of amide I and II for I-C are similar to those for I-A, but obviously different from those for I-B. Raman scattering intensities corresponding to the CH3 and CH2 vibrations also depend on the sample preparation methods. A simple model simulation suggests that the above observations would be attributed to the configuration change in the side chain of the amide group. The trans isomer is dominant in sample I-B and cis isomer dominant in samples I-A and I-C. (C) 1997 Elsevier Science Ltd.
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Record 61 of 70
Author(s): Zeng, F; Tong, Z; Feng, HQ
Title: Nmr investigation of phase separation in poly(N-isopropyl acrylamide)/water solutions
Source: POLYMER, 38 (22): 5539-5544 OCT 1997
Abstract: H-1 and C-13 n.m.r. spectra of poly(N-isopropyl acrylamide) (PNIPA) in D2O and CDCl3 were measured at several temperatures encompassing the lower critical solution temperature (LCST) about 32 degrees C of the PNIPA/water solution, using a high resolution n.m.r. spectrometer (500 MHz for proton). The PNIPA/CDCl3 is homogeneous in the temperature ranging from 16 to 36 degrees C and the hydrogen bonds of the amide groups are weakened by the solvation of CDCl3 and broken by heating. In the PNIPA/D2O solution, the proton and C-13 spectra are well resolved below the LCST. Whereas at temperatures above the LCST, all the resonance peaks except that for water proton became broad and the spectra lost their fine structure. The integral intensity of the water proton relative to that of the lone proton in the isopropyl group increases with increasing temperature, suggesting that some water molecules appear to be released out of the hydrated shells around the polymer chains. When the solution was heated from 22 to 35 degrees C, the spin-lattice relaxation time T-1 for the proton of the methyl group in the isopropyl residue increased, while that for the protons of the methylene and methyne groups of the backbone chain decreased. This indicates that during heating the relaxation of the isopropyl side chain slows down and that of the main chain speeds up. The phase separation was qualitatively interpreted with the Nemethy-Scheraga model for the hydrophobic bonding. (C) 1997 Elsevier Science Ltd.
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Record 62 of 70
Author(s): Liu, XX; Hu, O; Tong, Z
Title: Viscosity behavior of polyelectrolyte copolymers containing sulfonate groups in mixed organic solvents
Source: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 35 (9): 1433-1438 JUL 15 1997
Abstract: Copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS, monomer I)with 2-hydropropyl methacrylate (HPM, monomer 2) was conducted in ethylene glycol/water (1 : 1 in weight) at 70 degrees C. The reactivity ratios estimated from the copolymer composition at low conversion are r(1) = 2.31 +/- 0.25 and r(2) = 11.70 +/- 1.05. The azeotropic composition was found at the monomer mole ratio AMPS/HPM equal to 8/2. Viscosity of these copolymers was measured in dimethyl sulfoxide (DMSO) and DMSO/tetrahydrofuran (THF) mixed solvent at 25 +/- 0.05 degrees C. Polyeletrolyte behavior was observed for all the copolymers, even in the mixed solvent containing 65 wt % of THF. The reduced viscosity at constant polymer concentration decreased with increasing THF content in the mixed solvent. The copolymers having AMPS repeat units more than 42 mol % precipitated in the mixed solvent when the THF was beyond 68 wt %. The viscosity reduction and precipitation in the copolymer solutions with increasing THF can be attributed to the dipole-dipole attraction between ion-pairs formed in less-polar medium. This is helpful in understanding the volume phase transition in highly charged hydrogels caused by mixing solvents. (C) 1997 John Wiley & Sons, Inc.
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Record 63 of 70
Author(s): Liu, XX; Tong, Z; Cao, XW; Hu, O
Title: Volume phase transition of polyelectrolyte gels in dimethyl sulfoxide/tetrahydrofuran mixtures
Source: POLYMER, 37 (26): 5947-5949 DEC 1996
Abstract: Copolymer gels were prepared from 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), N,N-dimethylacrylamide (DMAA, comonomer) and N,N'-methylenebis(acrylamide) (BIS). The mole fraction of AMPS were 0.2674 and 0.4318, respectively, with the same BIS mole fraction of 0.013. These gels with counterions H+, Na+, and K+ were swollen at 25 degrees C in mixtures of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF). A volume phase transition was observed at the THF volume fraction of about 0.58, indicating that the volume phase transition in a polyelectrolyte gel occurs when the medium polarity decreases sufficiently for ion-pair formation. On changing the counterion, the fraction of DMSO in the solvent mixture which is required to initiate swelling decreases in the order Na+, H+, and K+, the same as for counterion condensation in identical gels. Copyright (C) 1996 Elsevier Science Ltd.
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Record 64 of 70
Author(s): TONG, Z; YI, YH; LIU, XX
Title: COPOLYMERIZATION OF 2-ACRYLAMIDO-2-METHYLPROPANE SULFONIC-ACID WITH 2-HYDROPROPYL METHACRYLATE
Source: POLYMER BULLETIN, 35 (5): 591-597 NOV 1995
Abstract: Copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS, monomer 1) with 2-hydropropyl methacrylate (monomer 2) was conducted in pure water at 80 degrees C. The reactivity ratios estimated from the compositional data of the copolymers at low conversion are r(1)=0.04+/-0.04 and r(2)=6.30+/-0.48, and values of Q(1) and e(1) are 0.16 and 1.37, respectively. Copolymer microstructure predicted by statistical calculation shows mean sequence length of M(1) shorter than 2. These results can be attributed to the strong repulsion between the ionized chain radical and charged monomer of AMPS.
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Record 65 of 70
Author(s): LIU, XX; TONG, Z; HU, O
Title: SWELLING EQUILIBRIA OF HYDROGELS WITH SULFONATE GROUPS IN WATER AND IN AQUEOUS SALT-SOLUTIONS
Source: MACROMOLECULES, 28 (11): 3813-3817 MAY 22 1995
Abstract: Swelling equilibria for five sulfonate gels were carried out in water and in aqueous solutions of NaCl, KCl, CaCl2, Na2SO4, K2SO4, and CaSO4 with concentrations ranging from 10(-6) to 1 M;at 25 degrees C. These samples were the same DS series of gels used in our previous paper, which were copolymerized using the ionizable monomer 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), the comonomer N,N-dimethylacrylamide (DMMA), and the cross-linker N,N'-methylenebis(acrylamide) (BIS). The mole fraction f of AMPS in the gel network ranged from 0.0899 to 0.6076. Before swelling the proton in the gel was exchanged by neutralization to the same cation as that in the salt solution to be equilibrated. The swelling capacity increases with increased charge density in the gels and with decreasing salt concentration. NaCl or KCl solutions more concentrated than 1 M were needed to screen the charge interaction in the DS50 (f = 0.4318) and DS70 (f = 0.6076) samples. The swelling ratios of DS50 and DS70 gels swollen in pure water acid in the salt solutions were found to depend on the counterion species in the increasing sequence as Ca2+, Na+, and K+, which cannot be interpreted with the concept of ionic strength. These phenomena seem to be the results of counterion condensation.
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Record 66 of 70
Author(s): TONG, Z; MEISSNER, K; WOLF, BA
Title: PHASE-EQUILIBRIA AND INTERFACIAL-TENSION BETWEEN COEXISTING PHASES FOR THE SYSTEM WATER 2-PROPANOL POLY(ACRYLIC ACID)
Source: MACROMOLECULAR CHEMISTRY AND PHYSICS, 196 (2): 521-527 FEB 1995
Abstract: The cloud point curve, tie-lines and interfacial tensions were measured for solutions of 50 mol-% neutralized (counter-ion Na-circle plus) poly(arylic acid) (mass-average molar mass (M) over bar(w) = 9 700 g/mol; polydispersity index (M) over bar(w)/(M) over bar(w) = 2,0) in the mixed solvent water/2-propanol at 30 degrees C. Due to the non-uniformity of the polymer, the end-points of the tie-lines are not situated on the cloud-point curve. The interfacial tension sigma - determined by means of the spinning drop method - increases in sigmoidal manner with R(t1), the length of the tie-line, expressed in terms of weight fractions. An evaluation of these data in a double-logarithmic plot of sigma.M(-0,5) versus R(t1) yields a critical exponent of 4,23 as compared with 3,85 in the case of binary systems. The dependence of a on w(w), the over-all weight fraction of water in the mixture, can also be expressed as a power-law choosing (w(cw)-w(w))/w(cw) as the concentration variable (w(cw): critical weight fraction of water); for the present system the exponent of the resulting equation amounts to 2,33 as compared with 2,0 for toluene/polyisobutylene/poly(dimethylsiloxane).
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Record 67 of 70
Author(s): TONG, Z; LIU, XX
Title: SWELLING EQUILIBRIA AND VOLUME PHASE-TRANSITION IN HYDROGELS WITH STRONGLY DISSOCIATING ELECTROLYTES
Source: MACROMOLECULES, 27 (3): 844-848 JAN 31 1994
Abstract: Several sulfonic acid copolymer gels were prepared by radical copolymerization of N,N-dimethylacrylamide (DMAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) using N,N'-methylenebisacrylamide (BIS) as the cross-linker. The concentration of pregel solutions and BIS content in dried gels were held constant at 0.75 mol/L and 1.3 mol %, respectively, while the mole fraction f of AMPS in dried gels determined by elemental analysis varied from 0 to 0.608. Swelling ratios for our sample of f = 0.468 were compared with those for an acrylic acid copolymer gel of f = 0.494 and 25 degrees C in aqueous buffers from pH = 2 to pH = 10 at 0.01 M ionic strength, and the results indicated that even in the gel state the sulfonic acid group could dissociate completely in the whole pH range. Therefore, f in this work can be designated to represent the charge density in the swollen gels. The swelling capacity observed in pure water at 25 degrees C increases monotonically with increasing f, showing a higher increasing rate when f > 0.3 without any sign of counterion condensation. The experimental swelling curve was interpreted with the Flory-Huggins theory and with the Hasa-Ilavsky-Dusek (HID) theory, but both theories failed to provide a reasonable approach to the swelling equilibria in our gels with a large amount of strongly dissociating electrolytes. The reciprocal of polymer volume fraction in a swollen gel, 1/phi, predicted with the Flory-Huggins theory was much higher than that observed when f > 0.2, while the calculated results given by the HID theory using the experimental nominal value of chain density were considerably lower than measured data in the entire f range. A volume phase transition occurred in these gels when f > 0 when the acetone volume fraction V-a in the acetone/water mixture was beyond a certain value, and this transition could be attributed to the weakening of electrostatic repulsion during increasing V-a in the mixture.
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Record 68 of 70
Author(s): TONG, Z; LIU, XX
Title: DYNAMIC-MECHANICAL BEHAVIOR OF POLYELECTROLYTE GELS WITH SULFONIC-ACID GROUPS
Source: MACROMOLECULES, 26 (18): 4964-4966 AUG 30 1993
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Record 69 of 70
Author(s): TONG, Z; LIU, XX
Title: SWELLING EQUILIBRIA AND VOLUME PHASE-TRANSITION OF PARTIALLY NEUTRALIZED POLY(ACRYLIC ACID) GELS
Source: EUROPEAN POLYMER JOURNAL, 29 (5): 705-709 MAY 1993
Abstract: Seven ionized gel samples of poly(acrylic acid) made by radical polymerization and having stoichiometric neutralization degree (f) ranging from 0 to 1, were examined. The ionization degree (alpha) is about a half the value of f for each sample. The data of swelling equilibrium in water as a function of alpha were interpreted with the Konak-Bansil equation; fair agreement was obtained if the effect of counterion condensation was considered. Volume phase transition in water/acetone was considered. Volume phase transition in water/acetone mixtures was found for five samples with high alpha values; the acetone concentration needed to induce the transition became lower for samples with higher alpha.
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Record 70 of 70
Author(s): TONG, Z
Title: APPARENT 2ND VIRIAL COEFFICIENT-GAMMA FOR TERNARY SOLUTIONS OF 2 POLYMERS IN A SOLVENT
Source: MACROMOLECULES, 24 (20): 5734-5735 SEP 30 1991
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