5,15-二（二茂铁基）-卟啉酞菁钇的结构和振动光谱的密度泛函理论研究

本文选用混杂的B3LYP密度泛函理论方法,在Lanl2dz水平上,对5,15-二（二茂铁基）-卟啉酞菁钇[Por(Fc)2]Y(Pc)的结构进行了优化,结果表明,5,15-二（二茂铁基）-卟啉酞菁钇呈现出三明治型构型,卟啉环与酞菁环呈穹型围绕在金属钇原子周围。对分子内主要的键长与键角进行了理论计算,通过频率计算,得到了5,15-二（二茂铁基）-卟啉酞菁钇[Por(Fc)2]Y(Pc)的红外光谱图,与实验所得的红外光谱图进行比对,将理论计算和实验所得的光谱主要振动峰进行了线性回归拟合,相关系数为0.992,标准偏差为16.96。理论计算与实验所获得的红外光谱图基本一致,说明本文所选用的DFT理论计算方法是可行的。通过GaussView软件对5,15-二（二茂铁基）-卟啉酞菁钇的红外谱带简正振动模式进行了指认。此外,分析讨论了5,15-二（二茂铁基）-卟啉酞菁钇[Por(Fc)2]Y(Pc)的分子静电势,确定了极大值与极小值的位置。对于研究5,15-二（二茂铁基）-卟啉酞菁钇分子的性质,提供了相应的理论基础。     

基于神光Ⅲ原型的激光直接驱动自由面准等熵实验研究

长脉冲激光打靶的直接驱动方式效率较高,但对激光强度变化非常敏感。利用测量自由面速度历史的方法对激光直接驱动准等熵压缩实验技术进行了分析,为改进激光直接驱动的准等熵压缩实验技术提供技术基础。介绍了国内在神光III原型装置上首次开展的激光直接驱动自由面准等熵压缩实验。对实验靶型、激光波形、典型实验结果以及实验中的关键技术进行了分析。在激光能量为1000 J的实验中,使用成像型速度干涉仪获得了较为理想的准等熵压缩条纹图。实验发现,自由面速度达到11.3 km/s时,自由面反射的探针光信号消失。通过对比Multi-1D软件的理论模拟数据与实验处理的结果,发现由于Al自由面缺少约束,这类实验会造成波系复杂化的问题,但是对主冲击的研究还是有意义的。对某些特殊材料,在很难找到阻抗匹配窗口的条件下,利用激光直接驱动方式研究材料高压响应特性提供了另一条可实施的技术途径。     

大学物理演示实验工作的新思路、新进展

北京交通大学在“国家工科物理教学基地”建设的过程中,以建设物理演示与探索实验室为特色工作,取得了突出成绩．不仅在2004年国家工科物理教学基地验收时以其突出的特色,获得了“优秀基地”的称号,而且在2005年获得国家教学成果特等奖．我们认为这并不意味着这项工作的结束,而是以此做为将演示实验工作推向更高水平的开端．从2007年开始,我们一方面不断充实提高,保持演示实验室的动态发展;另一方面着力研发随堂演示实验并投入使用,取得了显著成效．     

LED毫伏级待测电动势实验仪的设计及其稳定性的研究

为了满足电位差计实验对毫伏级待测电动势需求,设计了LED毫伏级待测电动势实验仪,并对其稳定性进行了研究.待测电动势实验仪是通过光电转换来实现的,输出的毫伏级电动势在电位差计实验仪的各个测量点都能稳定,能够满足箱式电位差计测量范围和精度要求,是比较理想的箱式电位差计实验配套仪器,能够大大提高学生的实验效率和教师对实验设计的选择性,实验效果良好.     

金属-有机骨架材料二聚铜-苯-1，3，5-三羧酸酯中烷烃扩散机理的分子模拟研究

采用分子动力学方法研究了直链烷烃C₁—C₄在二聚铜-苯-1,3,5-三羧酸酯（Cu-BTC）中的扩散机理.首先计算了4种烷烃的自扩散系数,并进一步通过质心分布图与分子轨迹图详细讨论了主、次孔道中各种类型的扩散路径.研究结果表明,不同烷烃在Cu-BTC中表现出的不同或近似的宏观扩散速率,是由微观上受到不同的扩散路径阻力并偏好不同的扩散路径所造成的.这些信息可提高人们对该类材料的认识,并为材料的实际应用以及新材料设计提供理论指导. 关键词： 分子模拟 二聚铜-苯-1 5-三羧酸酯 烷烃 扩散机理     

Room-temperature direct-bandgap photoluminescence from strain-compensated Ge/SiGe multiple quantum wells on silicon

Strain-compensated Ge/Si_0.15Ge_0.85 multiple quantum wells were grown on an Si_0.1>Ge_0.9 virtual substrate using ultrahigh vacuum chemical vapor deposition technology on an n⁺-Si(001) substrate. Photoluminescence measurements were performed at room temperature, and the quantum confinement effect of the direct-bandgap transitions of a Ge quantum well was observed, which is in good agreement with the calculated results. The luminescence mechanism was discussed by recombination rate analysis and the temperature dependence of the luminescence spectrum.     

Improved crystal quality of GaN film with the in-plane lattice-matched Ino.17Alo.s3N interlayer grown on sapphire substrate using pulsed metal-organic chemical vapor deposition

We report on an improvement in the crystal quality of GaN film with an Ino.17Alo.83N interlayer grown by pulsed metal-organic chemical vapor deposition, which is in-plane lattice-matched to GaN films. The indium composition of about 17% and the reductions of both screw and edge threading dislocations （TDs） in GaN film with the InA1N interlayer are estimated by high resolution X-ray diffraction. Transmission electron microscopy （TEM） measurements are employed to understand the mechanism of reduction in TD density. Raman and photoluminescence measurements indicate that the InA1N interlayer can improve the crystal quality of GaN film, and verify that there is no additional residual stress induced into the GaN film with InA1N interlayer. Atomic force microscopy measurement shows that the InA1N interlayer brings in a smooth surface morphology of GaN film. All the results show that the insertion of the InA1N interlayer is a convenient method to achieve excellent crystal quality in GaN epitaxy.     

Spectroscopic Studies of the Stability of Doped Polythiophenes Under Air

Abstract

The stability of the doped state of conductive polythiophenes under air was investigated by the use of Infrared (IR) and UV-visible (UV) spectroscopies. Poly(3-methyl thiophene) doped with BF₃-ethyl ether (BFEE). shows higher stability due to its stereoregularity-chain structure. While the doped polythiophene (PT) degrades easily under the moisture.     

新型嘧啶单环类非经典叶酸拮抗剂的合成及抗肿瘤活性研究

以课题组前期设计合成的非经典叶酸拮抗剂6-(4'-甲基苯乙基)-N5-氯乙酰基-2,4-二氨基哌啶并[3,2-d]嘧啶(wm-8.2)为先导化合物,将wm-8.2中的哌啶并嘧啶双环结构简化为嘧啶单环结构,以提高分子柔韧性并简化分子结构,根据6-位空间占位设计6-H和6-甲基两个系列,考察了不同桥链长度和不同芳香杂环侧链...     

Design of activatable red-emissive assay for cysteine detection in aqueous medium with aggregation induced emission characteristics

A novel water-soluble red-emissive AIE fluorescence probe for cysteine (Cys) in situ was prepared and the performance of selectivity and sensitivity has been carefully investigated in this study. The probe was established on the electrostatic interaction of sulfonate functionalized tetraphenylethene (TPE) and polycation generated by the reaction between a polymer bearing dinitrobenzenesulfonate groups and Cys. From the experimental results, it was easy to distinguish Cys from glutathione (GSH) and homocysteine (Hcy) with a detection limit of 73 nmol/L. The assay system also possessed strong anti-interference ability against multitudinous amino acids. The Stokes shift was 142 nm and the emission ranged from 550 nm to 850 nm. In addition, double responses in fluorescence and ultraviolet-visible spectra also make the red-emissive assay ideal for sensitive detection and quantification of Cys for most purposes, especially in-situ monitoring of Cys in aqueous medium.