EFFECTS OF COUPLING AGENTS ON THE CRYSTALLIZATION BEHAVIOR OF PP/T-ZnOw COMPOSITES

The objectives of this paper are to understand the crystallization behavior of polypropylene(PP)composites with surface modified tetra-needle-shaped zinc oxide whisker(T-ZnOw).T-ZnOw was surface modified with different coupling agents,such as silane coupling agents(KH-550,KH-560)and titanate coupling agent(NDZ-105),in order to improve the compatibility between PP and T-ZnOw.DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites,respectively.The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization,depending on the coupling agent used for modification.KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size.The results also suggest that the crystallization behavior depends on not only the content of coupling agent,but also the content of the surface modified T-ZnOw used in the composites.     

一种新的敏化/猝灭室温磷光: CTAB胶束中α-溴代萘敏化联乙酰的室温磷光猝灭

本文首次报道了将敏化和猝灭同时偶合在同一体系中的敏化/猝灭室温磷光新方法。体系中, CTAB胶束一方面增强α-溴代萘的室温磷光发射、α-溴代萘和联乙酰的三重态-三重态能量转移效率, 另一方面起到猝灭α-溴代萘敏化联乙酰发射的室温磷光的作用。CTAB对联乙酰的猝灭反应由三重态-三重态能量转移速率限制,求得α-溴代萘敏化联乙酰的三重态-三重态能量转移速率常数为1.76×10^9(mol.dm^-^3)^-^1s^-^1, CTAB对联乙酰的猝灭常数为7.82×10^7(mol.dm^-^3)^-^1s^-^1。详细研究了实验条件, 实现了猝灭法测定联乙酰,检测限达2.8×10^-^8mol.dm^-^3。     

占吨酮敏化的α-蒎烯的光化学异构化反应

占吨酮敏化可以显著提高α-蒎烯异构化罗勒烯的转化率.这一实验观察在反应过程的动力学分析中得到了说明,此外,也讨论了敏化异构化反应的光化学.     

Possible Tests of Curvature Effects in Weak Gravitational Fields

The possibility of performing in proximity of the Earth experiments to test the predictions of general relativity for the trajectories of particles and photons in weak gravitational fields is studied. Three experiments are analyzed, all based on optical detection methods. The first experiment would allow to detect the tidal acceleration using a freely-falling Michelson interferometer. In a second experiment, based on laser-ranging methods, the relativistic correction to the classical gravity acceleration could be detected. Finally, the possibility of detecting light deflection induced by space curvature in an optical cavity with high-reflectivity mirrors is discussed.     

PREPARATION OF POLYETHERSULFONE ULTRAFILTRATION MEMBRANES FOR MILK CONCENTRATION AND EFFECTS OF ADDITIVES ON THEIR MORPHOLOGY AND PERFORMANCE

Polyethersulfone membranes were prepared from quaternary systems containing N,N-dimethylacetamide （DMAc） as solvent, polyvinylpyrrolidone （PVP） as constant additive and acetic acid, acetone and water as variable additives. Phase inversion via immersion precipitation was employed for manufacturing of membranes. The prepared films were immersed in the mixture of pure water and 2-propanol （30/70 vol%） as the non-solvent. Acetic acid caused an increment in the flux at high polymer concentration （16 wt%） and a decline in the flux at low polymer concentrations （10 wt% and 13 wt%）. Acetone and water as the solvent in the casting solution declined the flux at any polymer concentration tested. The morphology and performance of the prepared membranes were investigated by scanning electron microscopy and separation experiments using milk as the feed.     

Ligand effects on migratory insertion by the Heck reaction

Ligand effects on ethene insertion into a series of cationic phenylpalladium complexes with diverse bidentate phosphine ligands were studied by using the density functional methods. For the complexes with n-membered ring ligands (n = 4–6), a correlation was found between the ring size and the insertion barrier. This behavior was explained by considering the P—Pd—P bond angle. In the case of complexes with ligands of different rigidity, almost no difference was found for the insertion barriers. Furthermore, the bidentate phosphine ligand was systematically substituted by Me, t-Bu, F and Ph groups. It was found that the electron-donating substituents increased the insertion barrier, whereas the electron-withdrawing groups decreased it. The substantial increase of insertion barrier by the t-Bu group indicated that steric effect also had great effect on the migratory insertion.     

碳氟表面活性剂在分光光度分析中的应用III:全氟辛酸钠(SPEO)-溴化十六烷基三甲铵(CTAB)混合胶束微环境的性质

本文采用荧光探针、ESR自旋标记和NMR技术研究了SPFO-CTAB混合胶束的微环境性质。发现在CTAB溶液中添加SPFO, 使胶束内芯的微粘度增大, 微环境的极性(反映在介电常数上)减弱。由此推测SPFO插入了CTAB胶束的栅状层并与之形成混合胶束。     

惰性元素化合物相对论效应的研究 I. 相对论效应的计算

分子形成中的相对论效应定义。用相对论电荷迭代EHT程序ITEREX计算了惰性元素氟化物XeF2, XeF4, XeF6, KrF2和RnF2的相对论效应, 分别为-72.91,是-160.34,-281.82, -25.44和-220.7kJ·mol^-^1。惰性元素化合物的相对论效应都是负值, 使分子趋于稳定。还计算了IF和CsF的相对论效应, 分别是10.68和17.42kJ·mol6-^1, 均为正值, 使分子能量升高, 证实了相对论效应在惰性元素化合物中的重要作用。     

固体氨基酸中甲基碳自旋晶格弛豫的瞬态NOE效应

本文讨论了固体氨基酸中^1^3C-{^1H}的瞬态核Overhauser效应(NOE),指出当^1^3C自旋晶格弛豫时间T~1^C小于质子的自旋晶格弛豫时间T~1^H时,^1^3C自旋晶格弛豫过程将出现明显的瞬态NOE效应。固体L-异亮氨酸有四个不等价的甲基,其中一个基团满足上述条件,实验上观测到了这种明显的瞬态NOE效应,本文对这一事实作了讨论。