基质隔离红外光谱结合理论计算研究第五族金属原子和硫化氢反应

利用基质隔离红外光谱结合理论计算,研究了激光溅射获得的第五族金属原子和硫化氢分子的反应. 结果表明金属原子插入H₂S的H-S化学键形成HMSH分子(M=V,Nb,Ta). 对Nb和Ta该HMSH分子重排为H₂MS分子. HMSH分子和H₂S进一步反应生成H₂M(SH)₂分子. 通过D₂S和H₂³⁴S同位素标定确定了产物的分子结构,同时我们用DFT(B3LYP和BPW91)理论计算预测了产物分子的能量、结构和振动频率. 通过DFT IRC计算研究了第五族金属原子和₂S分子的反应机理. HVSH分子通过光照解离为VS和H₂,然后通过退火可以发生VS和H₂复合反应. 计算表明HVSH释放H₂需要16.9 kcal/mol的活化能及吸热13.5 kcal/mol.     

长江三峡库区典型滑坡降雨诱发的概率分析

降雨是诱发滑坡发生或复活的主要因素。作者根据对长江三峡库区典型滑坡的分析，得到几个典型滑坡降雨诱发的阀值，并利用阀值分析了典型滑坡降雨诱发的概率。     

Abnormal magnetoresistance behavior in Nb thin film with rectangular arrays of antidots

Magnetoresistance in superconducting Nb films perforated with rectangular arrays of antidots (holes) is investigated at various temperatures and currents. Normally, the magnetoresistance increases with the increasing magnetic field. In this paper, we report a reverse behavior in a certain range of high fields after vortex reconfiguration transition, where the resistances at non-matching fields are smaller than those in the low field regime. This phenomenon is due to a strong caging effect, in which the interstitial vortices are trapped among the pinned multiquanta vortices. This effect is temperature and current dependent.     

无糖饮料中阿斯巴甜及其水解成分的探究——介绍一个国外本科生实验并讨论其相关问题

化学与人们的日常生活有广泛且紧密的联系。国外本科生化学基础理论与实验教学常与生活中的化学物质及现象良好结合,这既使得学生可以利用化学知识解释或解决生活中的问题,又利于培养学生对于化学的兴趣。介绍一个国外的本科生实验,即通过简单的水解反应和薄层色谱法定性鉴定无糖饮料中常见的甜味剂阿斯巴甜及其水解产物。阿斯巴甜作为一种重要的食品添加剂具有最简单的苯丙氨酸-天冬氨酸二肽甲酯结构,本实验也同时研究了多肽在酸或碱条件下的水解反应,可谓一举多得。此实验的安排与施行值得国内有机化学实验借鉴,对于让学生认识与理解多肽的一级结构有助,并为今后的生物化学学习奠定基础。     

关于机修工修理定额的优化研究

1.引言随着企业管理改革的深入,如何科学地制定机修工的修理定额,这是当前每个工矿企业管理部门所关注的问题.在我国,以前往往是山工厂的有关部门领导根据经验估计,规定出各个工种机修工的修理定额.但是在实施中,常常会出现定额过高或过低,以致造成人员紧张或停机过多的情况.结果常常直接影响企业的生产效益和机修工的积极性.针对我国日前工矿企业普遍存在的这个问题,本文就某厂根据现有的各种类型机器数和机修工人数,利用 Palm 机器干扰系统,建立了问题的最优化数学模型.根据问题的特点,本文给出一种 Marginal Anglysis 法的改进算法进     

In-plane optical spectral weight redistribution in the optimally doped Ba_(0.6)K_(0.4)Fe_2As_2 superconductor

We performed detailed temperature-dependent optical measurements on optimally doped Ba0.6K0.4Fe2As2 single crystal, We examine the changes of the in-plane optical conductivity spectral weight in the normal state and the evolution of the superconducting condensate in the superconducting state. In the normal state, the low-frequency spectral weight shows a metallic response with an arctan （T） dependence, indicating a T-linear scattering rate behavior for the carriers. A high energy spectral weight transfer associated with the Hund＇s coupling occurs from the low frequencies below 4000 cm^-1 5000 cm^-1 to higher frequencies up to at least 104 cm^-1. Its temperature dependence analysis suggests that the Hund＇s coupling strength is continuously enhanced as the temperature is reduced. In the superconducting state, the FGT sum rule is conserved according to the spectral weight estimation within the conduction bands, only about 40% of the conduction bands participates in the superconducting condensate indicating that Ba0.6K0.4Fe2As2 is in dirty limit.     

Evolution of the 251 cm^-1 infrared phonon mode with temperature in Ba_0.6K_0.4Fe₂As₂

The far-infrared optical reflectivity of an optimally doped Ba1-xKxFe2As2(x =0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 cm-1 . This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continuously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observations indicate that the structural and magnetic phase transition might be completely suppressed by chemical doping in the optimally doped Ba0.6K0.4Fe2As2 compound.     

非线性Tavis-Cummings模型压缩光场的Pancharatnam相位特性

研究了存在非线性Kerr介质时,耦合双原子与单模压缩真空场相互作用系统的Pancharatnam相位特性。选取合适的初始条件和运用旋波近似,通过解薛定谔方程求出Pancharatnam相位的表示形式,并对此相位进行数值分析。结果表明：耦合双原子处于任意初态,随着原子与光场相互作用强度、两个二能级原子偶极-偶极耦合强度和非线性Kerr介质非线性的增大,Pancharatnam相位演化的频率都显著增长。耦合双原子初态同处激发态时,pancharatnam相位演化有明显的振荡上升（或振荡下降)的趋势。耦合双原子初态只有一个处于激发态时,随着Kerr介质非线性作用的增强,Pancharatnam相位演化变混乱。