Lyapunov analysis of the approximate motion equations of flexible structures

In this paper, the effectiveness of the approximate motion equations of a flexible structure, obtained by the RitzKantorovich method, is analysed by using Lyapunov functions. The analysis, which is restricted to the case of a single flexible beam for the sake of simplicity, is carried out under the assumption that a partial dissipation is present, affecting only the first degrees of freedom of the system. By means of suitable Lyapunov functions, an overbounding estimate of the quadratic approximation error is determined as a decreasing function of the approximation order. The analysis is completed by considering the two ‘extreme’ cases: the theoretical absence of dissipation and the presence of structural dissipation, affecting all the infinite degrees of freedom.     

Ab initio calculations on the mechanism of isobutane and 2-butene alkylation reaction catalyzed by hydrofluoric acid

Ab initio method was employed to determine the mechanism of alkylation reaction of 2-butene with isobutane. The results indicated that 2-butene is rapidly protonated to form sec-butyl carbonium ion, which then reacts with isobutane to form tert-butyl carbonium ion. The resulting carbonium ion is then deprotonated to form isobutene that reacts rapidly with tert-butyl carbonium ion to form trimethylpentane (TMP) carbonium ion. Finally, the TMP⁺ carbonium ion is converted to TMP via the hydride transfer process. The transition states of the interactions were obtained by using the SCAN method (a calculation key word for potential energy surface) first and then the intrinsic reaction coordinates were traced using the Gaussian program. In addition, the energy changes and geometric parameters of the interactions were analyzed. The computed results indicated that the energy barriers are close to or less than zero for the interaction of isobutane with protonated 2-butene or for the interaction of tert-butyl carbonium ion with isobutene, suggesting rapid reaction steps of the carbonium ions. The 2,2,3-TMP is kinetically controlled, while the formation of 2,2,4-TMP is controlled by reaction equilibrium. The calculated results were in good agreement with the experimental results.     

共轭高分子三阶非线性光学材料

概述了ｎ－共轭高分子材料的三阶非线性光学性质，着重讨论了化学结构对其光学非线性的影响，说明了ｎ－共轭聚合物的三阶非线性极化率主要取决于共轭主链的结构，侧链取代基的变化对其非线性影响不大，文中展望了共轭高分子材料在集成光学中的应用前景。     

VAc／MMA半连续乳液共聚合的研究：Ⅱ分子量及其分布

以过硫酸铵为引发剂，十二烷基硫酸钠为乳化剂，于７０℃下进行了ＶＡｃ／ＭＭＡ乳液共聚合试验。试验确定了不同组成ＶＡｃ／ＭＭＡ共聚物的Ｍａｒｋ－Ｈｏｕｗｉｎｋ方程参数Ｋ和α值。对ＧＰＣ测试数据处理给出了加料速率，乳化剂量，单体比例及种子与非种子法对分子是及其分布的影响。     

Reasoning about non-immediate triggers in biological networks

Modeling molecular interactions in signalling networks is important from various perspectives such as predicting side effects of drugs, explaining unusual cellular behavior and drug and therapy design. Various formal languages have been proposed for representing and reasoning about molecular interactions. The interactions are modeled as triggered events in most of the approaches. The triggering of events is assumed to be immediate: once an interaction is triggered, it should occur immediately. Although working well for engineering systems, this assumption poses a serious problem in modeling biological systems. Our knowledge about biological systems is inherently incomplete, thus molecular interactions are constantly elaborated and refined at different granularity of abstraction. The model of immediate triggers can not consistently deal with this refinement. In this paper we propose an action language to address this problem. We show that the language allows for refinements of biological knowledge, although at a higher cost in terms of complexity.      

Fluctuation X-ray microscopy: a novel approach for the structural study of disordered materials

Measuring medium‐range order is a challenging and important problem in the structural study of disordered materials. We have developed a new technique, fluctuation x‐ray microscopy, that offers quantitative insight into medium‐range correlations in disordered materials at nanometre and larger length scales.In this technique, which requires a spatially coherent x‐ray beam, a series of speckle patterns are measured at a large number of locations in a sample using various illumination sizes. Examination of the speckle variance as a function of the illumination spot size allows the structural correlation length to be measured. To demonstrate this technique we have studied polystyrene latex spheres, which serve as a model for a dense random‐packed glass, and for the first time have measured the correlation length in a disordered system by fluctuation X‐ray microscopy. We discuss data analysis and procedures to correct for shot noise and detector noise. This approach could be used to explore medium‐range order and subtle spatial structural changes in a wide range of disordered materials, from soft matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials.     

A study of the static and dynamic properties of side-chain liquid crystalline polymers in low molar mass mesogens

The static and dynamic properties of solutions of a side chain polysiloxane liquid crystal polymer have been studied in a cyanobiphenyl nematic host as a function of concentration and temperature. Refractive index measurements were carried out on aligned samples and the data used to determine the macroscopic order parameter, S, using Haller's method. Photon correlation spectroscopy has been used to measure ($\text{k}{}_{22}\text{γ}{}_1$) for the pure nematic solvent and the solutions. From these measurements it appears that the static properties vary slowly and linearly with increasing polymer concentration whilst the dynamic or viscoelastic properties change markedly. This change has been attributed to γ₁, the twist viscosity, and the results have been discussed in terms of the function of the siloxane polymer backbone.     

Kerr介质中"耦合双原子-单模光场"模型的反聚束效应

利用全量子理论,研究了在Kerr介质中,耦合二能级双原子与单模光场相互作用过程的反聚束效应,着重讨论了Kerr介质对场的二阶相干度的影响,并揭示了初始场强及原子间耦合系数的变化与场的二阶相干度的关系。     

Shared syntactic representations in bilinguals: Evidence for the role of word-order repetition.

Studies on syntactic priming strongly suggest that bilinguals can store a single integrated representation of constructions that are similar in both languages (e.g., Spanish and English passives; R. J. Hartsuiker, M. J. Pickering, & E. Veltkamp, 2004). However, they may store 2 separate representations of constructions that involve different word orders (e.g., German and English passives; H. Loebell & K. Bock, 2003). In 5 experiments, the authors investigated within- and between-languages priming of Dutch, English, and German relative clauses. The authors found priming within Dutch (Experiment 1) and within English as a 2nd language (Experiments 2 and 4). An important finding is that priming occurred from Dutch to German (Experiment 5), which both have verb-final relative clauses; but it did not occur between Dutch and English (Experiments 3 and 4), which differ in relative-clause word order. The results suggest that word-order repetition is needed for the construction of integrated syntactic representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)