Computer Simulation Study on Adsorption and Conformation of Polymer Chains Driven by External Force

In this work, Monte Carlo simulations are used to study the critical adsorption behaviors of flexible polymer chains under the action of an external driving force F parallel to an attractive flat surface. The critical adsorption temperature T_c decreases linearly with increasing F,indicating that the driving force suppresses the adsorption of polymer. The conformation of polymer is also affected by the driving force.However, the effect of F is dependent on the competition between the driving force and temperature. Under strong force or at low temperature,the polymer is stretched along the direction of the force, while under weak force or at high temperature, the polymer is not stretched. When the force is comparable to the temperature, the polymer may be stretched perpendicular to the driving force, and below T_c, we observe conformational transitions from parallel to perpendicular and again to parallel by decreasing the temperature. We found that the perpendicular stretched conformation leads the polymer chain to synchronously move along the direction of the driving force. Moreover, the conformational transitions are attributed to the competition and cooperation between the driving force and the temperature.     

职前与在职化学教师对教学能力认知差异的实证研究*

采用定量的方法对112位化学师范生和83位中学化学教师进行问卷调查,了解职前、在职教师对教学能力要素重要性认识的情况,问卷涉及本体要素、工具要素、条件要素、实践要素、情意要素和发展要素等6大维度。基于Rasch测量模型,利用ConQuest,Winstep,SPSS22.0软件对数据进行统计分析。研究发现:(1)问卷具有良好的信效度;(2)师范生、在职教师均把情意要素作为教学能力的首要成分,其次依次是本体要素、发展要素、实践要素,工具要素与条件要素排在其他要素之后;(3)工具要素重要性赞同度师范生显著高于在职教师,其余维度差异不显著,不同性别各维度重要性赞同度也无显著性差异;(4)由ConQuest多维分析所建立的项目被试图可以直观展示不同维度上各教学能力的重要程度。     

Common extension of bilateral series for Andrews’ q-Bailey and q-Gauss sums

By means of the modified Abel lemma on summation by parts, we establish a common bilateral series extension of the q-Bailey and q-Gauss sums discovered by Andrews (Duke Math. J. 40 (1973), 525–528).     

The Aharonov–Casher effect for spin-1 particles in non-commutative quantum mechanics

By using a generalized Bopp’s shift formulation, instead of the star product method, we investigate the Aharonov–Casher (AC) effect for a spin-1 neutral particle in non-commutative (NC) quantum mechanics. After solving the Kemmer equations both on a non-commutative space and a non-commutative phase space, we obtain the corrections to the topological phase of the AC effect for a spin-1 neutral particle both on a NC space and a NC phase space. PACS 02.40.Gh, 11.10.Nx, 03.65.-w     

The He--McKellar--Wilkens effect for spin-1 particles on non-commutative space

By using star product method, the He-McKellar-Wilkens （HMW） effect for spin-one neutral particle on noncommutative （NC） space is studied. After solving the Kemmer-like equations on NC space, we obtain the topological HMW phase on NC space where the additional terms related to the space-space non-commutativity are given explicitly.     

A new modified remote user authentication scheme using smart cards

In 2000, a remote user authentication scheme using smart cards was proposed and the masquerade attacks were proved successful on this scheme. Recently, Kumar has suggested the idea of check digits to overcome the above attacks with a new scheme that removes these threats well. In this paper it is pointed out that the weakness still exists in Kumar＇s scheme, and the intruder can login to the remote system through having some information. A new scheme which can overcome these attacks and appears more secure and efficient than Kumar＇s is presented.     

Iterative processes for common fixed points of two different families of mappings with applications

In this paper, an implicit iterative process is investigated for common fixed points of two different families of nonlinear mappings. Theorems of strong and weak convergence are established in real Hilbert spaces. As an application of the iterative process, inclusion problems are considered.     

Generalized system for relaxed cocoercive mixed variational inequalities in Hilbert spaces

The approximate solvability of a generalized system for relaxed cocoercive mixed variational inequality is studied by using the resolvent operator technique. The results presented in this paper are more general and include many previously known results as special cases.     

Microfluidic System for Synthesis of Trigonal Selenium Nanowires

<正>A microfluidic system was developed for the synthesis of trigonal selenium(t-Se) nanowires,which was composed of a glass microchip coupled with a poly(methyl methacrylate)(PMMA) microchip.In the glass microchip, amorphous selenium(a-Se) colloid was prepared by reducing selenious acid with an excess amount of hydrazine at a temperature of 100℃.In the coupled PMMA microchip,a-Se was transformed into more stable t-Se seeds via sonication at room temperature.The residence time of the reactants in both microchips was optimized by varying the dimension and length of the microchannel each.The t-Se nanowires were formed by anisotropic growth of selenium crystallite during sonication and aging under the assistance ofβ-cyclodextrin(β-CD).Various stages of the nanowires' growth were investigated.The as-synthesized products were characterized by powder X-Ray diffraction(XRD),Raman spectroscopy,scanning electron microscopy(SEM),transmission electron microscopy(TEM) and selected-area electron diffraction(SAED).