An Electrostatic Bond Energy Model for Enthalpies of Formation of Chloroalkanes in Gaseous States

An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.     

高压静电场促进植物生长技术的研究

高压静电场促进植物生长技术源于自然又高于自然 ,它包括静电种子处理和静电场生长环境等技术 .文章论述了该技术的实施方法 ,并报道了已经取得的初步成果 .     

Influence of Generalized (r, q) Distribution Function on Electrostatic Waves

Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping of electron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r,q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.     

一些静电场能量公式的适用范围

讨论并给出了一些静电场能量公式的适用范围,指出明确公式的适用范围是运用这些公式的前提．     

Efficiency enhancement of InGaN based blue light emitting diodes with InGaN/GaN multilayer barriers

The advantages of InGaN based light-emitting diodes with InGaN/GaN multilayer barriers are studied.It is found that the structure with InGaN/GaN multilayer barriers shows improved light output power,lower current leakage,and less efficiency droop over its conventional InGaN/GaN counterparts.Based on the numerical simulation and analysis,these improvements on the electrical and the optical characteristics are mainly attributed to the alleviation of the electrostatic field in the quantum wells(QWs) when the InGaN/GaN multilayer barriers are used.     

基于密度泛函理论的菲分子结构与光谱研究

选用密度泛函理论(DET)中的B3LYP方法,在6-311++G(d,p)下对菲分子结构进行优化,计算了其振动频率、极化率及热力学参数,对比了菲分子实测光谱图,首次对其振动频率进行了完全归属。此外,分析并讨论了其前线分子轨道、分子静电势和密立根布局,获得了HOMO-LUMO能隙、分子静电势分布、原子电荷分布等与分子性质密切相关的重要数据,为后续其他多环芳烃分子的光谱检测技术及其光谱和电子结构的分析提供了理论基础。     

从平面角和立体角讨论静电场中的某些电场等价性

本文利用平面角的概念讨论了均匀带电的直线微元和圆弧微元在圆心处的场强等价性,并将结论推广到一些均匀带电的线几何体;然后利用立体角的概念进一步讨论带电的平面微元和球面微元在球心处的场强等价关系,结果表明,只有非均匀的电荷面密度才能使两者等价．     

用定性定量系列演示整治静电教学中的顽症

本文针对静电学教学中出现的一些重点、难点，提出了定性定量的演示方案。     

静电场描绘的一种改进方法

本文介绍的是使用算术平均法作出等势线,描绘静电场。与课本中的方法进行比较,结果误差更小,更准确的描绘了静电场的分布。     

Protonation state and free energy calculation of HIV-1 protease–inhibitor complex based on electrostatic polarisation effect

The protonation states of catalytic Asp25/25′ residues remarkably affect the binding mechanism of the HIV-1 protease–inhibitor complex. Here we report a molecular dynamics simulation study, which includes electrostatic polarisation effect, to investigate the influence of Asp25/25′ protonation states upon the binding free energy of the HIV-1 protease and a C₂-symmetric inhibitor. Good agreements are obtained on inhibitor structure, hydrogen bond network, and binding free energy between our theoretical calculations and the experimental data. The calculations show that the Asp25 residue is deprotonated, and the Asp25′ residue is protonated. Our results reveal that the Asp25/25′ residues can have different protonation states when binding to different inhibitors although the protease and the inhibitors have the same symmetry. This study offers some insights into understanding the protonation state of HIV-1 protease–inhibitor complex, which could be helpful in designing new inhibitor molecules.