水中铬污染治理的研究进展

综述了水中铬污染治理的研究进展,包括物理法、物理化学法、化学法、电化学法和生物处理法,并分别评述了各种处理方法的优缺点,提出了未来含铬废水治理的发展方向。     

Measurement of Secondary Electron Energy Spectra of Polymethyl Methacrylate

We report on a novel and convenient method of measuring secondary electron spectra for insulators in a secondary electron yield measurement system with a planar grid analyzer configuration and a metal mesh probe. In this measurement, the planar grid is negatively biased to force some emitted secondary electrons to return to the sample surface and to neutralize charges accumulated on the sample during the previous beam irradiation. The surface potential of the sample is then measured by use of a metal mesh probe. The grid bias for neutralization corresponding to the zero surface potential is determined based on the linear relationship between the surface potential and the grid bias. Once the surface potential equals zero, the secondary electron spectra of polymethyl methacrylate(PMMA) are studied experimentally by measuring the -curve and then fitting it to Everhart's formula. The measurement results show that the peak energy and the full width at half maximum of the spectra are 4.26 eV and 14.06 eV, respectively.     

电动修复土壤中重金属污染的改良方法

介绍了治理土壤重金属污染的电动修复技术的一些进展,包括:通过控制电解过程中的极化、土壤pH值、控制土壤温度来对电动修复技术方法进行改良。     

宽气压范围空气中微波击穿电场的计算公式

为了简便快捷地计算微波击穿电场,依据电子扩散模型的基本理论,结合气体放电的基本参量,应用特征扩散长度的概念,给出了适合于规则结构微波部件的击穿电场的计算方法。为避免各种气体参数的不确定性对计算准确度的影响,对等效直流电场与特征扩散长度之间的实验关系进行了拟合,并根据等效直流电场的定义,得出了一个适用于较高气压范围的击穿电场计算表达式。为了将该计算表达式扩展到更低的气压范围,综合考虑了电子扩散模型和基于二次电子发射现象的真空微放电机理,引入了一个合理形式的等效扩散长度,进一步给出了适合于更广气压范围的微波击穿电场的计算表达式,计算结果更符合A.D.Macdonald的实验结果。