An Auger electron spectroscopy-secondary ion mass spectrometry study of layers of Cu-Ni and Ag-Au alloys modified by ion bombardment

The effects of argon ion bombardment on the surface layers of Cu-Ni and Ag-Au alloys were studied. Mechanisms considered were preferential sputtering, enhanced diffusion and thermodynamic segregation. An Auger electron spectroscopy-secondary ion mass spectrometry combined system was used to determine the composition-depth profiles from several tens of ångströms below the surface. The variation of the depth profile in the layer modified as a result of ion bombardment revealed that above room temperature the outermost layer was always enriched with copper or silver for the respective alloys compared with the second and the third layers. The results indicated that thermodynamic segregation played an important role in determining the depth profile of the altered layer as well as preferential sputtering and enhanced diffusion.     

Intravenous extended infusion of recombinant human soluble thrombomodulin prevented tissue factor-induced disseminated intravascular coagulation in rats

This study demonstrated that intravenous infusion of recombinant human soluble thrombomodulin (rhs-TM) could inhibit disseminated intravascular coagulation (DIC) caused by 4 hr infusion of tissue factor (TF) in rats. Extended infusion of TF reduced fibrinogen and platelet counts and elevated serum FDP level. Pretreatment and coinfusion of rhs-TM could block changes of these DIC-parameters without prolongation of APTT. Heparin, which is a potent anti-DIC drug, could also inhibit these changes with extra prolongation of APTT and PT. Thus, these results suggest thrombomodulin prevent DIC less bleeding tendency than heparin.     

The evidence of clonal evolution with monosomy 7 in aplastic anemia following granulocyte colony-stimulating factor using the polymerase chain reaction

The polycyclic aromatic hydrocarbons (PAH) containing fractions of smoked and charcoal-broiled foods, namely, Sheat fish (Kytopterus apogon), Mimrow (Crossocheilus reba), Freshwater catfish (Clarias batrachus), chicken wings, rice pork sausage and pork, in addition to naphthalene, acenaphthene, anthracene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene, naphthacene, benzo[a]pyrene, benzo[e]pyrene, 9,10-dimethyl-1,2-benzanthracene, dibenz[ah]anthracene, benzo[ghi]perylene and coronene, were evaluated for their mutagenic potential using Salmonella typhimurium strains TA98 and TA100 in the absence of metabolic activation after being treated with nitrite (500 mM) for 4 hr at 37 degrees C and in acid solution pH 3.0-3.5. The presence of N-nitroso compounds was also determined. Results showed that nitrite could convert most samples to direct-acting mutagens towards both strains except for fluoranthene and benzo[ghi]perylene, which exhibit mutagenicity only with TA98. It was demonstrated that treatment of PAHs with nitrite in acid solution produced some non-N-nitroso direct-acting mutagens, suggesting that they might belong to nitro-PAHs. Therefore, the consumption of charcoal-broiled and smoked foods simultaneously with nitrite is not recommended.     

SiC coatings for first-wall candidate materials by R.F. sputtering

The r.f. sputtering technique was applied to form SiC coating films on first-wall candidate materials such as molybdenum, stainless steel and pyrolytic carbon at various temperatures. The coating films were examined by means of scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy and roughness factor (RF) measurements. It was found that the coating films consisted of α-SiC and grew at relatively low temperatures, namely 300 °C, 600 °C and 800 °C on molybdenum, 304 stainless steel and pyrolytic carbon surfaces, respectively. The surfaces of α-SiC films grown above these temperatures were relatively smooth with small RFs in comparison with those prepared at lower temperatures. Lower temperature deposition gave rise to amorphous and rough coating films with considerably larger RFs.     

Microcomputer Control for Sensorless Brushless Motor

The microcomputer control of a brushless motor without a shaft position sensor is studied. A method which permits the determination of the permanent magnet rotor position by the back electromotive force (EMF) induced in the stator windings and the starting technique which uses the motor as a synchronous motor at standstill are explained. The motor voltage is chopped by commutator transistors to change the motor speed. The control system consists of a 4-b single-chip microcomputer and two quad-comparators.     

弧焊机器人焊缝跟踪神经网络控制器

介绍了一种能提高高弧焊机器人焊缝跟踪精度的神经网络控制器,通过神经网络的补偿作用,弥补了由于无法知道机器人精确模型所造成的控制上的误差,不同于机器人控制中传统的网络控制器,本文提出并应用了基于笛卡尔空间轨迹控制的机器人焊缝跟踪神经网络,大大简化了控制算法,计算机模拟及实验表明,该控制器非常适用于只的实际焊接,对于现有机器人,无须改变其控制器内部结构,即可应用该技术,与常用的机器人关节力矩控制法相比     

Composition Regulation by Flow Copolymerization of Methyl Methacrylate and Glycidyl Methacrylate with Free Radical Method

It is important to match the feeding ratio of comonomers to the composition ratio in the resulting copolymers as closely as possible in industrial production, where the goal is often to produce more a homogeneous composition in copolymers. In this study, a flow copolymerization system with a conventionally initiated free radical method, together with randomly selected polymerization conditions is investigated. It is succeeded in achieving a closer match between the composition ratio and feeding ratio than previously reported in the copolymerization of styrene with methyl methacrylate and of glycidyl methacrylate with methyl methacrylate, which will widen the range of applications, by precisely controlling the mixing and heating in a flow polymerization apparatus. This is confirmed by the fact that the estimated values of reactivity ratios, r₁ and r₂, which are used in the reaction kinetics of copolymerization, are close to 1.     

The role of silanol groups on the reaction of SiO2 and anhydrous hydrogen fluoride gas

It is essential to etch SiO₂ for producing silica glass components, semiconductor devices, and so on. Although wet-etching with hydrogen fluoride (HF) solutions is usually employed for this purpose, it faces a drawback that microstructures stick during the drying of the solution. To overcome this problem, we have developed a dry-etching technique with gaseous HF at high temperatures. In the present study, an interesting phenomenon was found that silicon thermal oxides were much less etched than vitreous silica by gaseous HF. Such difference had not been found in wet- or humid HF gas etching. Because their bulk chemical formulae are the same (SiO₂), it was suggested that the surface species affected the reaction rate. In fact, preprocessing with water vapor plasma remarkably increased the etching rate on the thermal oxides layer, and vacuum heating almost completely suppressed the reaction on the vitreous silica and the plasma-treated thermal oxides. These results indicate that the surface silanol groups enhance the reaction between SiO₂ and gaseous HF. Based on the results, a model of chain reaction for SiO₂ and gaseous HF was proposed, where the surface silanol groups act as the reaction center.