Polypropylene/poly(butyl methacrylate) blends prepared by diffusion and subsequent polymerization of butyl methacrylate in isotactic polypropylene pellets

Polypropylene/poly(butyl methacrylate)(PP/PBMA) blends were prepared by diffusion and subsequent polymerization of butyl methacrylate(BMA) in commercial isotactic polypropylene(iPP) pellets.The diffusion kinetics,diametrical distribution of PBMA in a pellet and phase morphology of a typical PP/PBMA blend were investigated.     

Stochastic resonance in an asymmetric bistable system driven by coloured correlated multiplicative and additive noise

This paper investigates the stochastic resonance （SR） phenomenon in an asymmetric system with coupling between multiplicative and additive noise when the coupling between two noise terms is coloured. The approximate expression of signal-to-noise ratio has been obtained by applying the two-state theory and SR exhibits in the bistable system. Moreover, the potential asymmetry r and cross-correlation strength λ can weaken the SR phenomenon, while the cross-correlation time r can strengthen the SR phenomenon.     

全谱拟合法研究聚丙烯腈基碳纤维形成过程中晶态结构演变

通过全谱拟合法对碳纤维制备过程中不同阶段纤维的XRD谱图进行处理,得到不同阶段纤维的微观结构参数,研究了聚丙烯腈(PAN)基碳纤维制备过程中晶态结构的演变.全谱拟合法基于晶体衍射的严格物理理论,拟合目标为整个衍射谱,并不是个别衍射峰,所得结果具有更高的可信度.研究结果表明:PAN原丝中的高分子链沿纤维轴高度取向,表观晶粒尺寸为6.5 nm左右;经过预氧化处理,纤维中的有序结构遭到破坏,表观晶粒尺寸锐减.纤维中逐渐形成梯形结构并沿纤维轴取向,从而形成新的有序结构;经过碳化处理后,环状梯形结构转变为碳的层状结 关键词： 碳纤维 晶体结构 XRD 全谱拟合法     

正交小波变换在散斑图象相关计算中的应用

本文在散斑图象的相关计算处理技术中引入了二维离散正交小波变换,详细叙述了其原理,给出了实验计算的结果,并与原始的空域相关计算进行了比较,从中可以看出:无论是相关计算精度,还是相关搜索速度,小波相关都具有明显的优越性.     

镁离子内扩散铌酸锂研究(Ⅱ)—— X射线衍射和扫描电子显微镜表征

对不同扩散条件的铌酸锂单晶基片进行了X射线衍射分析(XRD)和扫描电子显微镜观察(SEM)。结果表明,在扩散表面富镁层出现一新相结构,可能是由Li-Mg-Nb-O组成的三元系相结构,这一新相被认为是镁离子内扩散的真正扩散源。并对晶格发生畸变、镁离子内扩散机理以及镁的扩散层折射率变化机理进行了分析和讨论。 关键词：     

CuAPTPP-TDI-TiO2光催化微球的合成及其光催化性能 (cited: 1)

采用Adler法合成了5-(4-氨基苯基)-10,15,20-三苯基卟啉铜配合物(CuAPTPP),通过甲苯二异氰酸酯(TDI)的桥联作用对TiO₂微球进行表面修饰,使TDI分子中的两个活性TDI基团分别与TiO₂表面的羟基和CuAPTPP的氨基反应,将CuAPTPP敏化剂分子以化学键合的方式固定在TiO₂表面,形成光催化微球CuAPTPP-TDI-TiO₂．通过FT-IR、XRD、SEM、EA、UV-Vis和DRS等测试手段对CuAPTPP-TDI-TiO₂进行结构表征．讨论了桥联分子TDI修饰量对光催化微球性能的影响,确定了TDI与TiO₂的最佳摩尔比．以亚甲基蓝(MB)为降解对象,考察了CuAPTPP-TDI-TiO₂微球的可见光催化性能．结果表明,桥联分子TDI在CuAPTPP与TiO₂微球表面形成了牢固的化学键,复合微球在150 W氙灯辐照下降解10 mg/LMB溶液,120 min降解率可达98.7%,其降解率过程服从一级动力学规律,测得降解速率常数为5.1×10^-2 min^-1,半衰期为11.3 min．催化微球在回收4次的条件下,对MB的降解率仍保持在90%以上．     

A growth kinetics model of rate decomposition for Si1-xGex alloy based on dimer theory

According to the dimer theory on semiconductor surface and chemical vapor deposition(CVD) growth characteristics of Si1-xGex, two mechanisms of rate decomposition and discrete flow density are proposed. Based on these two mechanisms, the Grove theory and Fick’s first law, a CVD growth kinetics model of Si1-xGex alloy is established. In order to make the model more accurate, two growth control mechanisms of vapor transport and surface reaction are taken into account. The paper also considers the influence of the dimer structure on the growth rate. The results show that the model calculated value is consistent with the experimental values at different temperatures.     

Asymmetric Synthesis, Antifungal Activity and Molecular Modeling of Iodiconazole Isomers

Iodiconazole is a novel antifungal agent that was developed in its racemic form. In order to investigate the ef- fects of the chiral center on the antifungal activity, R- and S-isomers of iodiconazole were prepared on the basis of the asymmetric Sharpless epoxidation. （S）-Iodiconazole was proved to have better antifungal activity than the （R）- isomer. The binding modes of the two isomers with lanosterol 14~z-demethylase were clarified by molecular dock- ing.     

Identification of urinary metabolites of imperatorin with a single run on an LC/Triple TOF system based on multiple mass defect filter data acquisition and multiple data mining techniques

The detection of drug metabolites, especially for minor metabolites, continues to be a challenge because of the complexity of biological samples. Imperatorin (IMP) is an active natural furocoumarin component originating from many traditional Chinese herbal medicines and is expected to be pursued as a new vasorelaxant agent. In the present study, a generic and efficient approach was developed for the in vivo screening and identification of IMP metabolites using liquid chromatography-Triple TOF mass spectrometry. In this approach, a novel on-line data acquisition method mutiple mass defect filter (MMDF) combined with dynamic background subtraction was developed to trace all probable urinary metabolites of IMP. Comparing with the traditionally intensity-dependent data acquisition method, MMDF method could give the information of low-level metabolites masked by background noise and endogenous components. Thus, the minor metabolites in complex biological matrices could be detected. Then, the sensitive and specific multiple data-mining techniques extracted ion chromatography, mass defect filter, product ion filter, and neutral loss filter were used for the discovery of IMP metabolites. Based on the proposed strategy, 44 phase I and 7 phase II metabolites were identified in rat urine after oral administration of IMP. The results indicated that oxidization was the main metabolic pathway and that different oxidized substituent positions had a significant influence on the fragmentation of the metabolites. Two types of characteristic ions at m/z 203 and 219 can be observed in the MS/MS spectra. This is the first study of IMP metabolism in vivo. The interpretation of the MS/MS spectra of these metabolites and the proposed metabolite pathway provide essential data for further pharmacological studies of other linear-type furocoumarins.