Metric Properties of Factor Space of Molecular Shapes

Molecular shape equivalence classes defined with respect to equivalence of geometrical and topological properties are represented by logical models. Consequently, the factor space of molecular shapes is provided by a metric useful in shape comparisons.     

[All]-S,S-dioxide Oligo-Thienylenevinylenes: Synthesis and Structural/Electronic Shapes from Their Molecular Force Fields

Oligo-S,S-dioxothienylenevinylenes have been prepared by transferring oxygen atoms to the sulfur atoms using the HOF ⋅ CH₃CN complex. Their photophysical properties are presented in comparison with their thiophenevinylene congeners. Together with their vibrational properties and molecular force fields, this study allows for the interpretation of the alteration of aromaticity and inter-ring exocyclic π-conjugation in this series.     

拉胀复合物中不同形状包埋体的泊松比的理论分析

１．论文名称　ＰｏｉｓｓｏｎＲａｔｉｏｉｎＣｏｍｐｏｓｉｔｅｓｏｆＡｕｘｅｔｉｃｓ２．发表刊物　Ｐｈｙｓ．Ｒｅｖ．Ｅ，１９９８，５８，６１７３．３．研究者　魏高原（北京大学化学与分子工程学院高分子科学与工程系　北京１００８７１）；ＥｄｗａｒｄｓＳＦ（ＰｏｌｙｍｅｒｓａｎｄＣｏｌｌｏｉｄｓＧｒｏｕｐ，ＣａｖｅｎｄｉｓｈＬａｂｏｒａｔｏｒｙ，ＵｎｉｖｅｒｓｉｔｙｏｆＣａｍｂｒｉｄｇｅ，Ｃａｍｂｒｉｄｇｅ，ＣＢ３０ＨＥ，ＵＫ）４．评介者　童真（华南理工大学材料科学研究所　广州５１０６４１）５．研究工…     

金属表面分子纳米结构的构筑及性质研究

结合近期研究工作, 简要介绍了在溶液环境下, 利用有机分子在金属表面构筑纳米结构, 利用光化学反应方法调控所得的纳米结构, 利用电化学扫描隧道显微镜对这些结构进行观察, 及利用毛细管隧道结方法测量纳米结构电学性质的相关结果. 并展望了表面纳米结构的构筑、控制和性质研究领域的发展趋势.     

含环氧基聚二甲基硅氧烷及其硫化过程的分子运动

采用扭辩分析法详细研究了含环氧基聚二甲基硅氧烷在１１０－２３０Ｋ范围内的的分子运动情况，讨论了氧基团对聚二甲基硅氧烷主链的玻璃化转变温度，次级转变温度、烷融温度及粘流浊国度等动态力学性能的影响。     

Photoelectron Spectra of Nonmetal Compounds and Their Interpretation by MO Models

The results of (low energy) photoelectron spectroscopy render possible a better appreciation of the “Nature of the Chemical Bond”. The application of this new experimental method is demonstrated utilizing representative compounds of the nonmetal elements, and a close symbiosis delineated with molecular orbital models. In particular, general consequences are discussed concerning electron deficiency, σ- and π-interactions, electron pair delocalization, and substituent effects or geometric perturbations. Photoelectron spectroscopic ionization energies permit evaluation of parameters for specified molecular groups, allow correlation with numerous other experimental data, and are didactically valuable in the teaching of general chemistry.     

分子信标的构建及其应用研究进展

分子信标（molecular beacon,MB）是一种寡聚核苷酸荧光探针,其具有灵敏度高、特异性强、操作简单以及不必与未反应的探针分离即可实时检测等优点,在分子生物学和基因组学及分子医学等领域具有十分重要的应用价值。 本文介绍了近年来出现的各种新型分子信标的结构及工作原理,概述了分子信标技术在生命科学领域中的应用,展望了分子信标技术的发展趋势。     

粘土层间金属络合物催化剂及其分子识别催化作用

粘土的可膨胀的二维空间有助于将催化活性的金属络合物阳离子交换法和配位体交换法插入到粘土层间,因而易于制得粘土层间金属络合物催化剂,这是均相催化剂多相化的一种好方法,粘土层间金属络合物催化剂具有分子识别催化作用,择形选择性,立体选择性,区域选择性,本文论述了多种多相化催化剂上的对不对称加氢反尖,区域选择加氢反应,区域选择羰基化反应和空间选择芳基化反应,粘土层间金属络合物催化剂有高的活性和选择性,它可以与匀相金属络合物催化剂相媲美。     

Kinetic Models for Bulk Polymerization of Vinyl Chloride and Their Rate Expressions

The various models and their rate expressions developed for the bulk polymerization of vinyl chloride are checked against carefully evaluated experimental data. Only Ugelstad's and Olaj's models yield rate expressions consistent with experiment.     

功能化核酸适体的筛选及分子识别应用

核酸适体是从寡核苷酸文库中筛选获得的一段单链寡核苷酸. 由于能与多种靶标分子高特异性结合, 核酸适体已发展成为一种新兴的分子识别工具, 广泛应用于生物医学等领域. 天然核酸文库有限的化学组成限制了核酸适体的结构和功能, 进而限制了其在分子识别中的应用. 功能化核酸适体通过引入特定的化学官能团使核酸序列具有更丰富的构象和功能, 增强其分子识别能力. 然而, 功能化核酸很难与核酸扩增方法兼容, 因而难以使用传统筛选方法进行功能化核酸的筛选. 因此, 优化筛选方法对于获得具有优异性能的功能化核酸适体至关重要. 本综述总结了功能化核酸适体的筛选方法, 并介绍了其作为分子识别工具在生物医学领域中的应用.     

硒蛋白的分子生物学及与疾病的关系*

硒蛋白是微量元素硒在体内存在和发挥生物功能的主要形式。因硒蛋白的活性中心硒代半胱氨酸由传统终止码TGA编码,故从基因组中预测硒蛋白以及用基因工程技术表达硒蛋白均很困难。有关硒抗氧化、对癌症、神经退行性疾病和病毒作用的报导较多,但结论并不一致。本文综述了硒蛋白基因预测、蛋白质表达调控以及硒和硒蛋白对癌症、神经退行性疾病和病毒的作用及机制等方面的近期进展,研究提高硒蛋白生物信息学预测准确率和基因工程表达量的方法,分析了解硒蛋白与疾病发生发展的关系和机制,探索不同硒蛋白作为预防药物开发、作为癌症治疗和药物筛选靶标的可能性。     

甲基丙烯酸甲酯聚合动力学和分子量模型及仿真

考虑甲基丙烯酸甲酯聚合过程中体积收缩，反应物和生成物的浓度变化，以及由于凝胶、玻璃化和笼闭等效应对各速率常数和物性参数的影响，从基元反应和物料平衡出发，推导了半间歇，有链转移剂参与情况下的聚合动力学和分子量模型。用模型仿真计算了聚合温度、引发剂、溶剂和链转移剂的种类和浓度等对甲基丙烯酸甲酯聚合动力学和聚合过程中分子量变化的影响规律，并与实验和文献数据进行比较。     

Molecular Modeling Studies on Molecular Recognition: Crown Ethers,Cryptands and Cryptates. From Static Models in vacuo to Dynamical Models in Solution

Abstract

Molecular Mechanics, Monte Carlo and Molecular Dynamics simulations on free and complexed crown ethers, on bicyclic cryptands and cryptates provide deeper insights into their conformational and recognition properties and allow to address the questions of preorganisation, complementarity, and binding selectivity. Alternatively, references to experimental data allow to outline present theoretical and computational limitations. Of particular interest are the microscopic pictures obtained in solution, which demonstrate the importance of solvent and environment effects on the precise structure of free and complexed receptors, and on their dynamics. Quantitative insights into relative free energies in solution represents a most promising breakthrough for computational studies in molecular recognition.     

DSC Studies on Polytetrahydrofurans with Various Molecular Masses, Their Blends and Their Cured Samples

DSC studies are given for polytetrahydrofurans with molecular masses equal to 650, 1400, and 2900, for their blends, and for their cured samples. The samples were stored, annealed, and quenched to obtain the samples with different thermal histories. Two or more endothermic peaks appear in the DSC curves for the stored samples, even for the non-blended samples. A hyperbolic curve forced the plot of the highest melting temperature vs. the molecular mass to asymptote to about 50°C. The relationship between the highest melting temperature and the composition for the blended samples is suitable to linear or Fox’s relation. A peak and a shoulder appear in the DSC curves of the cured samples. As the samples are cooled at the faster rates in the thermal treatment, the shoulder appears at the lower temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Encapsulation of Vitamin C by Glycerol-Derived Dendrimers,Their Interaction with Biomimetic Models of Stratum corneum and Their Cytotoxicity

Vitamin C is one of the most sensitive cosmetic active ingredients. To avoid its degradation, its encapsulation into biobased carriers such as dendrimers is one alternative of interest. In this work, we wanted to evaluate the potential of two biobased glycerodendrimer families (GlyceroDendrimers-Poly(AmidoAmine) (GD-PAMAMs) or GlyceroDendrimers-Poly(Propylene Imine) (GD-PPIs)) as a vitamin C carrier for topical application. The higher encapsulation capacity of GD-PAMAM-3 compared to commercial PAMAM-3 and different GD-PPIs, and its absence of cytotoxicity towards dermal cells, make it a good candidate. Investigation of its mechanism of action was done by using two kinds of biomimetic models of stratum corneum (SC), lipid monolayers and liposomes. GD-PAMAM-3 and VitC@GD-PAMAM-3 (GD-PAMAM-3 with encapsulated vitamin C) can both interact with the lipid representatives of the SC lipid matrix, whichever pH is considered. However, only pH 5.0 is suggested to be favorable to release vitamin C into the SC matrix. Their binding to SC-biomimetic liposomes revealed only a slight effect on membrane permeability in accordance with the absence of cytotoxicity but an increase in membrane rigidity, suggesting a reinforcement of the SC barrier property. Globally, our results suggest that the dendrimer GD-PAMAM-3 could be an efficient carrier for cosmetic applications.     

CDK4与靛玉红及其衍生物复合物结构的模建

细胞周期蛋白依赖性激酶(Cyclin-dependent Kinases, CDKs)是细胞周期调控的重要因子, 也是治疗癌症的一类重要的药物靶标. 靛玉红是传统中药当归龙荟丸中治疗慢性疾病的有效成分, 靛玉红及其衍生物5-磺酸基-靛玉红对CDKs具有有效的抑制作用. 以获得晶体结构的CDK2与5-磺酸根-靛玉红的复合物为模板, 通过同源模建和分子对接的方法构建出的CDK4与靛玉红及其衍生物的结合模式. 结合CDK4与两种抑制剂的复合物结构, 解释了靛玉红和衍生物5-磺酸基-靛玉红之间抑制活性的差别, 同时也分析了5-磺酸基-靛玉红对CDK2和CDK4不同选择性的原因. 所建CDK4结构为进一步进行基于结构的抗癌药物设计提供了合理的模型.