ADSORPTION OF 1,2,4-ACID BY WEAKLY BASIC RESIN： ISOTHERMS, THERMODYNAMICS AND KINETICS

The adsorption properties, including the adsorption isotherms, thermodynamics and kinetics, of l-amino-2-naphthol-4-sulfonic acid (1,2,4-acid) onto weakly basic resin ND900 are investigated. Both the Langmuir and Freundlich equations can give a good fit to the adsorption isotherms, which indicates an endothermic and a favorable adsorption in our study range. A high yield in elimination of about 45.21%-97.28% is obtained for the tested adsorption systems. The capacity and affinity of the adsorption increase with temperature, due to the phenomena of “solvent-motivated” effects. The value of ΔH is 51.59 kJ/mol, which indicates a chemical adsorption and then expects the poor desorption property of ND900. The negative value of ΔG indicates the spontaneous nature of the adsorption process, and the positive value of ΔS shows the increased randomness at the solid/solution interface during the adsorption process. The value of the adsorption rate constant lower than 0.013 min^-1 is indicative of a slow adsorption rate. The intra-particle diffusion must be one of the rate limiting steps.     

磷叶立德CH2PH3和类磷叶立德自由基∙CHPH3优势构型和C—P键结构的研究

采用MP4/6-311++G(d,p)和B3LYP/6-311++G(d,p)对磷叶立德CH₂PH₃和类磷叶立德自由基∙CHPH₃进行构型优化，从电子密度拓扑分析的角度对C—P键的键结构进行了探讨。得到如下结论：类磷叶立德自由基和磷叶立德的C—P键性质类似，但磷叶立德中π键由两个电子形成，类磷叶立德自由基中π键由一个电子形成，所以前者的π性明显，而后者的π性不明显。类磷叶立德自由基中的这个单电子在碳原子附近，垂直于对称面的方向上运动，有p_(C→P)配键的特征，所以类磷叶立德自由基∙CHPH₃中的C—P键比相应的产物∙CH₂PH₂中的C—P键要弱一些。     

Effect of solvents on the electronic absorption spectra of some substituted diarylformazans

Summary The electronic absorption spectra of some substituted diarylformazans in organic solvents of varying polarities are studied. The absorption bands are assigned to the corresponding electronic transitions in the molecules. The solvent effects on the intramolecular charge transfer bands are discussed using various solvent parameters. The charge transfer nature of the bands was also confirmed by the solvent effects on the absorption spectra of some formazans. Molecular orbital calculations using MNDO-PM3 were performed and indicate atrans configuration as the favoured geometry.

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Lösungsmitteleinflüsse auf die Absorptionsspektren einiger substituierter Diarylformazane

Zusammenfassung Die Absorptionsspektren einiger substituierter Diarylformazane werden in organischen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Absorptionsbanden werden den entsprechenden Elekronenübergängen in den Molekülen zugeordnet. Die Lösungsmitteleffekte auf die intramolekularencharge-transfer-Banden werden unter Verwendung verschiedener Lösungsmittelparameter diskutiert. Diecharge-transfer-Natur der Banden wurde durch den Einfluß der Lösungsmittel auf die Absorptionsspektren einiger Formazane bestätigt. MO-Rechnungen (MNDO-PM3) wurden durchgeführt und bestätigen einetrans-Konfiguration als bevorzugte Geometrie.

     

Synthesis and radical polymerization of vinyl monomers having oxazolidone moiety

Oxazolidone group-containing vinyl monomers, 4-(2-oxo-3-oxazolidinyl)methylstyrene (OS) and 4-[2-(2-oxo-3-oxazolidinyl)ethoxy]methylstyrene (OES), were synthesized and their polymerization and copolymerization behaviors with styrene (St), p-methoxystyrene (PMS), and m-hydroxystyrene (MHS) were investigated. OS was prepared in 70% yield by the reaction of 2-oxazolidone with p-chloromethylstyrene in the presence of sodium hydride. OES was obtained by the similar reaction of p-chloromethylstyrene with N-hydroxyethyl-2-oxazolidone which was prepared by the reaction of 2-oxazolidone with ethylenecarbonate. Homopolymerization of OS and OES afforded mainly gelled polymers, but also soluble polymers on high dilution. In the copolymerization with styrene derivatives, an alternating nature was suggested from the copolymerization parameters obtained by either the nonlinear least-squares analysis method or the Fineman–Ross method. The alternating copolymerizability decreased in the following order: MHS > PMS > St. Q?e values of OS and OES were calculated and demonstrated that OS and OES behaved as stronger electron-accepting monomers in the copolymerization with MHS than in those with St and PMS. The copolymerization behavior of OS (OES) with MHS was compared with those of 4-(2-oxo-1-pyrrolidinyl)methylstyrene (PS) and 4-[2-(2-oxo-1-pyrrolidinyl)ethoxy]methylstyrene (PES). From an IR study examining the shift of carbonyl absorption by addition of MHS, the interaction which contributed to the increase of the alternating copolymerizability in the copolymerization of OS (OES) with MHS was concluded to be based on hydrogen bonding. © 1993 John Wiley & Sons, Inc.     

GROWTH AND MORPHOLOGY OF POLYMER-ACTIN COMPLEXES

F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes. Our results show that formation of polymer-actin complexes is cooperative, and morphology and growth of polymer-actin complexes depend on polycation species and concentrations of polycation and salt in a constant actin concentration. We found that the longitudinal growth and lateral growth of polymer-actin complexes are dominated by different factors. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolyte system have been discussed. Our results indicate that the semi-flexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth of actin architectures in cell.     

Four ring achiral ferroelectric liquid crystals of 1,2,4-oxadiazoles: synthesis and characterisation

A novel series of four-ring achiral ferroelectric liquid crystals containing 1,2,4-oxadiazole cores with unsymmetrical substitutions at C-3 and C-5 positions are synthesised and characterised. A fluoro substituted biphenyl moiety is prepared by Suzuki coupling reaction and is directly attached to the oxadiazole core at the C-5 position for the first time in the literature. An octyl benzoate is attached to the oxadiazole core at the C-3 position of it. All the compounds exhibit polar smectic (B₂) mesophases with ferroelectric switching along with the orthogonal smectic-A mesophases. These compounds possess high mesomorphic thermal ranges of polar smectic phases and are towards the ambient temperatures. The influence of a more electronegative fluorine substituent on the electron rich biphenyl moiety (at the C-5 position) of the oxadiazole core is analysed for the prevalence and abundance of polar smectic (ferroelectric) mesophases.     

Ultramicroscopic examination of mature massulae of Habenaria arinaria (Orchidaceae)

The mature massula of H. arinaria was examined by means of transmission electron microscopy, with the aim to understand the nature of cohesion between grains, the accumulation of pollen storage reserves, and the behavior of the nucleus of the vegetative cell in this composite type of pollen. The massula was a union of a large number of polygonal pollen grains that were tightly linked together. The exine within the massula were highly simplified, consisting of a single layer of nexine-2, lacking tectum, bacula, and nexine-1, while all the four layers comprised the exine on the massula surface. The two layers of nexine-2 of adjacent grains fused into a seamless whole. Undoubtedly the fusion of the nexine-2 was the mechanism by which the grains of the massula were linked together. No starch grains, lipid bodies, or storage proteins were present in the mature massula, and so the composite pollen of this species belonged to a novel type with regard to storage reserves. The vegetative nucleus was not lobed and revealed a huge amount of highly condensed chromatin, indicating a quiescent status. The condensed status of the vegetative nuclei in this composite type of pollen system is in striking contrast to the highly decondensed status reported in the free type of pollen grains.     

大学物理网上自学试点的实践与思考

《大学物理》网上自学试点（限正规在校生）是教育部资源委员会向全国推广远程教育的重大举措之一。本文通过回顾一学期网上自学试点的教学过程,总结了第一手资料,提出了一些有待探讨的问题,供读者借鉴和思考。     

将教师的科学本质观转化到课堂实践——国际文献综述

提高学生的科学本质观是国际科学教育的重要目标，教师在提高学生科学本质观的过程中发挥着重要作用。本研究在梳理国际科学本质教育文献的基础上，聚焦教师的科学本质观到课堂实践的转化。研究发现，教师的科学本质观无法自动转化为有效的课堂实践，影响“转化”的因素可从教师、学生和教材等3方面进行分析，最后从职前教师和在职教师的角度综述了促进“转化”的措施。     

回归自然理念下的室内设计

室内设计是现代科技和文化艺术的综合产物，它不仅折射出鲜明的社会时代特征，而且还反映了人与自然的关系，创造一个符合人性诉求、让人的心理和生理都感到自然和谐的居住空间已成为现代家居设计发展的趋势．而利用自然的设计元素，注重以人为本，构建自然、建筑和人三者之间和谐统一是以回归自然为理念的室内设计的根本．