The multi-structure of oxidized-reduced tungsten carbide surface(s)

The XPS of bulk tungsten carbide, partially oxidized WC surfaces at 373 and 573 K as well as tungsten trioxide have been reported. Bulk WC has been prepared from WO₃ as a starting material in a mixture of CH₄ (20%) and H₂ (80%) at 1150 K for 4 h, while partially oxidized WC surfaces were prepared by oxygen chemisorption on a clean WC surface at 200 K, then the temperatures were raised to 373 and 573 K respectively. The XPS of a freshly prepared WC reveals the presence of a small amount of WO₃ on the surface and a slightly higher concentration in the bulk. The oxygen-exposed fresh WC surfaces and surfaces treated at temperatures higher than 373 K show the presence of WO₃ in a considerable quantity depending on the length and the treatment temperature. Ar⁺ bombardment of this partially oxidized surface reduces WO₃ to WO₂ and W(0), while WC is partially reduced to W(0). Isomerization reactions of alkanes on oxygen-exposed WC surface occurs in reality on a composite surface structure containing WC, WO₃, WO₂ and elemental W(0).     

上海市吴淞工业区大气PM2.5水溶成分的元素分析及细胞毒性研究

通过ICP-MS测定了上海市吴淞地区大气PM2.5水溶成分金属元素含量,通过四唑盐(MTT)测定细胞存活率,通过超氧化歧化酶(SOD)和丙二醛(MDA)两个指标测定细胞氧化损伤,琼脂糖凝胶电泳测定细胞内DNA损伤,流式细胞仪(Flow cytometry)检测细胞凋亡和周期等实验研究了大气PM2.5水溶成分的细胞毒性.实验结果表明:PM2.5可溶成分中Zn元素含量最高,PM2.5在一定浓度范围内能导致细胞死亡,引起细胞的氧化损伤,影响DNA的复制,阻碍细胞增殖,但没有诱导细胞凋亡.PM2.5中可溶金属离子对细胞毒性表现为联合作用.     

离子注入机的国内外现状

本文简要介绍了离子注入和器件的关系,概述了离子注入机的发展现状和趋势,初步探讨了我国离子注入机不能形成产业的原因。     

强流质子直线加速器中束晕现象研究

从束流包络方程与单粒子运动方程联立模型出发，考虑了纵向能量方程的耦合，研究了强流质子直线加速器中的束晕现象。采用相交间的Ｐｏｉｎｃａｒｅ截面方法和实空间Ｐｏｉｎｃａｒｅ截面方法，研究了周期聚焦系统失配的情况下束晕的形成以及加速对束晕形成的影响。     

离子交换法合成三氨基胍叠氮酸盐

三氨基胍叠氮酸（ＴＡＺ）分子中的含氮量高达８５．７％，燃烧分解时不仅－Ｎ３可释放３６７ｋＪ／ｍｏｌ的键能，而且放出大量的氮气，是一个提高比冲，降低燃烧温度的理想的推进剂两组分之一。     

微波高压提取快速测定饲料含氟量的探讨

采用微波高压制样技术,快速提取饲料中的氟元素,结合氟离子选择性电极标准添加和电位极差测试方法,能够快速、准确地测试饲料中的含氟量     

High concentration erbium doping of silicon-rich SiO2 thin films on silicon

In this work, high concentration erbium doping in silicon-rich SiO₂ thin films is demonstrated. Si plus Er dual-implanted thermal SiO₂ thin films on Si substrates have been fabricated by using a new method, the metal vapor vacuum arc ion source implantation with relatively low ion energy, strong flux and very high dose. X-Ray photoelectron spectroscopy measurement shows that very high Er concentrations on the surfaces of the samples, corresponding to 10 at.% or the doping level of 10²¹ atoms cm⁻³, are achieved. This value is much higher than that obtained by using other fabrication methods such as the high-energy ion implantation and molecular beam epitaxy. Reflective high-energy electron diffraction, atomic force microscopy and cross-section high-resolution transmission electron microscopy observations show that the excess Si atoms in SiO₂ matrix accumulate to form Si clusters and then crystallize gradually into Si nanoparticles embedded in SiO₂ films during dual-ion implantation followed by rapid thermal annealing. Er segregation and precipitates are not formed. Photoluminescence at the wavelength of 1.54 μm exhibits very weak temperature dependence due to the introduction of Si nanocrystals into the SiO₂ matrix. The 1.54-μm light emission signals from annealed samples decrease by less than a factor of 2 when the measuring temperature increases from 77 K to room temperature.     

Study of Lateral Spread of Ions Emitted from 2.3 kJ Plasma Focus with Hydrogen and Nitrogen Gases

The characteristics of ion beams of hydrogen and nitrogen with different filling pressures emitted from the plasma focus device of 2.3 kJ energy are investigated. CR-39 SSNTDs are employed for the registration of tracks of ions. The exposed detectors are etched in 6N NaOH solution at 70°C and then examined with an optical microscope. The ion flux is estimated to be of the order of 10^5–6 tracks/cm². The flux with the radial position does not exhibit any regular pattern of variation.     

抽余C_4烃中异丁烯催化逆流水合制叔丁醇

采用大颗粒离子交换树脂催化剂,在φ100mm×10m的反应器中进行了异丁烯催化逆流水合制叔丁醇的中间试验。考察了反应温度、水油体积比和抽余C4烃的流速等对异丁烯转化率的影响。试验结果表明,异丁烯催化逆流水合制叔丁醇的适宜操作条件为:反应温度80~90℃,水油体积比为4~5,抽余C4烃的流速为0.45~0.55mm/s。在此条件下,异丁烯的转化率可达88.8%。工业装置运转结果表明,异丁烯转化率大于75%。     

内热式液态合金离子源

本文介绍了一种实用的液态合金离子源结构，我们利用本结构研制成功了Ａｕ－Ｓｉ和Ａｕ－Ｓｉ－Ｂｅ液态合金离子源，测出了它们的发射特性。