用SVR相机观测爆轰现象

给出了利用SVR电子相机进行多点起爆、爆炸成形弹丸和炸药爆轰驱动破片实验的测试方法,对实验结果进行了初步分析。结果表明,SVR相机可用于某些爆轰实验。     

Dynamics simulation on interaction of intense laser pulses with atomic clusters

Under classical particle dynamics, the interaction process between intense femtosecond laser pulses and icosahedral noble-gas atomic clusters was studied. Our calculated results show that ionization proceeds mainly through tunnel ionization in the combined field from ions, electrons and laser, rather than the electron-impact ionization. With increasing cluster size, the average and maximum kinetic energy of the product ion increases. According to our calculation, the expansion process of the clusters after laser irradiation is dominated by Coulomb explosion and the expansion scale increases with increasing cluster size. The dependence of average kinetic energy and average charge state of the product ions on laser wavelength is also presented and discussed. The dependence of average kinetic energy on the number of atoms inside the cluster was studied and compared with the experimental data. Our results agree with the experimental results reasonably well.     

Study of far-infrared reflection and Raman scattering spectra in reactive ion, etched ZnTe

Far-infrared reflection and Raman scattering measurements have been carried out on reactive ion, etched p-ZnTe samples. The averaged thickness of the surface damaged layer is found to be in the range of 1.0－1.5μm, and the, etch-induced defect density is in the order of 10^{18}cm^{-3}. The Raman intensity ratio between the second-order Raman peaks and the first-order longitudinal optical phonons reveals an increase trend with the radio frequency (rf) power. With the aid of related theories, we discuss the effects of the rf plasma power and the concentration of CH_4/H_2 on the damage, disorder, and the second-order Raman structures in p-ZnTe samples.     

沉淀相的尺寸与形态对镍基合金蠕变行为的影响

镍基合金具有优良的高温力学性能,广泛应用于涡轮叶片等热端部件。沉淀相的尺寸和形态是影响镍基合金力学性能的重要因素。本文在考虑应变梯度的镍基合金晶体塑性本构模型的基础上,引入了各向异性损伤张量,研究了包含两种不同尺寸和三种不同长细比的沉淀相形态的镍基合金蠕变行为。结果表明,该模型能够很好地反映沉淀相的尺寸对镍基合金蠕变行为的影响,与实验结果符合较好。同时,沉淀相的形态也对镍基合金的力学性能产生重要影响,随着沉淀相长细比的增加,镍基合金的蠕变寿命延长,这体现了粗化和形态对镍基合金蠕变行为影响的一种竞争的机制。     

Synthesis of monodisperse palladium nanocubes and their catalytic activity for methanol electrooxidation

The single crystalline palladium nanocubes with an average size of 7 nm were prepared in the presence of poly (vinyl pyrrolidone) (PVP) and KBr using the polyol method. The as-prepared Pd nanocubes were highly uniform in both size and shape. The ordered packing structures including monolayer and multilayer can be fabricated via the rate-controlled evaporation of solution solvent. The electrochemical catalytic activity of these Pd nanocubes towards methanol oxidation was found to be higher than that of spherical Pd nanoparticles of similar size.     

亚稳平衡吸附态与亚稳平衡系数关系的热力学研究

在相同温度、压力、pH值和离子强度等条件下,同一种金属离子在无机矿物表面上发生的吸附反应可以形成能量不同的吸附状态(如Zn可以边-边和角-角两种方式吸附在水锰矿表面上),因而反应终了时吸附质可处于不同的亚稳平衡吸附态(MEA).应用MEA理论,针对吸附反应A+H₂O=xA₁+yA₂+H₂O,推导出实际吸附反应“平衡常数”(Kreal)与亚稳平衡系数(Kme)的热力学关系式,从理论上分析了吸附反应MEA状态的变化对实际吸附反应平衡性质的影响.分析结果表明,Kme值与两种MEA状态之间的能量差呈指数关系,通过影响吸附反应的MEA状态(包括能量和组成)的反应动力学因素可影响吸附平衡常数和吸附等温式(线)等吸附热力学性质.     

基于微芯片电泳的脱氧核糖核酸片段的浓缩和分离

采用超负荷电动供给(electrokinetic supercharging, EKS)预浓缩技术,在微芯片电泳(MCE)上对脱氧核糖核酸（DNA）片段进行浓缩和分离。EKS是集合样品电动进样(EKI)和过渡等速电泳(tITP)的一种在线浓缩方法。研究表明：采用该方法后,在40.5 mm长的单通道芯片上能够实现对低浓度样品的大量进样、浓缩和基线分离。在普通的紫外检测条件(检测波长为260 nm)下,对DNA片段的平均检出限(S/N=3)约为0.07 mg/L,仅为十字芯片上的微芯片电泳检出限的1/40。本文还对浓缩过程中的一些关键因素和定性分析进行了探讨。     

也谈灰绿色物质——绿锈的组成

在制备氢氧化亚铁的过程中,白色沉淀会迅速变成灰绿色[1],但是对于灰绿色物质--绿锈成分的说法有很多种,有的说"这个灰绿色物质是由Fe(OH)2和Fe(OH)3以一定比例混合的特殊物质"[2],有的说"绿色沉淀不是Fe(OH)2和Fe(OH)3的简单混合物,而是有特定组成的一种特殊物质[3].     

Li2SO4水溶液结构X射线衍射测量条件的优化和数据校正

采用Ｄ／ＭＡＸ－３Ｂθ／２θ型Ｘ射线粉末衍射仪反射法,探索溶液结构研究的新方法。以Ｌｉ２ＳＯ４溶液的衍射实验为例,从狭缝和波长选择、步长及固定时间确定、峰背分离、溶液吸收校正、极化校正和荧光辐射校正等几个方面,重点讨论了Ｘ射线粉末法精确测量液体结构实验数据采集对策,给出了数据校正结果,即Ｌｉ２ＳＯ４溶液的衍射强度。     

用粉末X射线衍射技术研究溶液结构的新方法Ⅲ Li2SO4溶液的径向分布函数与模型计算

本文用折合强度和径向分布函数概念分析了由粉末 X射线衍射技术测量的Li2 SO4· 2 0 H2 O溶液强度数据 ,讨论了径向分布函数的主要误差来源 ,给出了 1 5nm- 1 ≤s≤ 1 65nm- 1 范围内获得的由最小二乘法精修的溶液结构模型参数。