Kinetic study of the hydrolysis of isocyanic acid in the gas phase

The hydrolysis of isocyanic acid in the gaseous phase has been investigated at temperatures between 553 and 613 K by mass spectrometry and evaluated to obtain the corresponding kinetic data. The reaction order and reaction constant have been determined. Finally, the influence of water on the catalysed formation of melamine from isocyanic acid under the operating conditions employed has been investigated in order to determine whether there is a need to try the process gas.     

Growth of Fe on Si (100) at room temperature and formation of iron silicide

Low-energy electron diffraction (LEED), Auger electron spectroscopy and X-ray photoelectron spectroscopy (XPS) investigations of both the growth of an iron film on silicon (100) at room temperature and the subsequent formation of iron silicide are the subjects of this paper. An in-situ cleaned silicon (100) wafer without carbon or oxygen contamination exhibiting the known 2 × 1 reconstruction in the LEED pattern served as the substrate. Iron was deposited on this reconstructed surface at 300 K. The comparison of theoretical calculations based on three growth mechanisms with XPS data obtained with take-off angles of 0° and 50° clearly demonstrates a layer-by-layer growth of the iron film on silicon (100). At 300 K no formation of iron silicide was observed, although an interaction between iron and silicon could be detected at the interface. The formation of iron silicide was observed at annealing temperatures of 630–730 K. Quantitative XPS analysis yields the presence of FeSi₂, when the thickness is large enough. Neither the iron film on silicon nor the silicide shows any LEED pattern.     

Mechanization techniques for poplar development in Turkey

Annual commercial poplar wood production in Turkey is about 3.6 million cubic meters, half of which comes from hybrid poplar I-214. The poplar plantation areas of Turkey are 70% of the poplar plantation areas of the Near and Middle Eastern countries, and nearly 5% of the world. In this study, unit times of standard operations were investigated in poplar nurseries and plantations in which new mechanical technology was applied and compared with traditional methods. Analyses of unit times were made on 11 treatments for poplar nurseries and nine treatments for poplar plantations; some new methods are also recommended. Mechanization methods based on new technologies give promising results in poplar nurseries and plantations.     

海底沉积物中天然气水合物生成和分解规律研究进展

对国内外有关海底沉积物中天然气水合物生成和分解规律方面的研究进行了详细调研,得到如下结论:天然气水合物的生成和分解条件在海底沉积物中与在井筒、管道中有明显不同,其主要原因是多孔介质中流体与孔隙壁面间的界面效应对海底沉积物中天然气水合物的形成条件会产生明显影响;在海底沉积物中天然气水合物生成和分解条件的数值模拟技术研究方面,研究者大都假设以天然气水合物作为盖层的成藏类型,借助常规油气藏数值模拟技术进行模拟研究;影响海底沉积物中天然气水合物生成和分解条件的因素很多,因此海底沉积物中天然气水合物生成和分解规律研究必须借助试验模拟、数值模拟和现场测试相结合的综合方式进行。该调研成果可为今后天然气水合物经济有效开采技术方案选择和进行天然气水合物危害控制等提供参考。     

Experimental Study of Concrete Subjected to Explosive Loading

The main subject of this paper is to demonstrate the response of structural concrete to different imposed strain rates. Attention is focused on the strain rate about 10^-2 s ^-1>, where some technical difficulties are experienced when an exact determination of mechanical properties for quasi-brittle materials is attempted. The design of a measurement system, which realizes computer acquisition, analysis, and graphic representation of data, is also presented.     

单晶钛酸铋纳米片的XPS和Raman特性

以Bi（NO3）3·5H2O和Ti（OC4H9）4为原料，NaOH为矿化剂，采用水热法制备了形貌规则的单晶Bi4Ti3O12纳米片。X射线衍射（XRD）结果表明，所合成的产物为正交相层状钙钛矿结构的Bi4Ti3O12。场发射扫描电子显微镜（FESEM）研究显示：样品是由大量边缘尺寸接近200nm，厚度约为15nm的片状结构组成。利用X射线光电子能谱（XPS）研究产物的化学组分和价态分布。室温拉曼光谱研究表明，Bi4Ti3O12纳米片的声子寿命和热稳定性低于相应的块体材料。     

Influence of pH on the passivation behavior of 254SMO stainless steel in 3.5% NaCl solution

The potentiodynamic polarization measurement of 254SMO stainless steel (UNS 31254) was conducted in 3.5% NaCl solutions with pH ranging from 0.1 to 5. The results indicated that this stainless steel offered excellent pitting corrosion resistance in corrosive environments. Further, it also exhibited various features on the polarization curves in different pH solutions. The electrochemical constant-potential passivation treatment performed at different pH followed by XPS analysis revealed that the primary constituents of the outermost layer of the passive films formed in the weak (pH 5) and strong (pH 0.8) acid solutions are iron oxides and Cr₂O₃ and Cr(OH)₃, respectively. Molybdenum oxides, primarily in the six-valence state, existed in the outermost layer of the passive film. Only very weak signals corresponding to that of nickel oxides were detected in the film formed in the weak acid (pH 5) solution. The ICP-MS analyses indicated selective dissolution of a significant amount of Fe and a few Mo and Ni ions during the passivation treatment in the strong acid (pH 0.8) solution. No Cr dissolution was observed; this indicated that the Cr in the film is relatively stable. XPS depth profiling results showed that a similar bilayer-structured film was formed in both the solutions (pH 0.8 and 5); the outer layer of this film is primarily composed of Cr(OH)₃ and Mo(VI), and the inner layer, Cr₂O₃ and Mo(IV). The results of the examinations of passive film formations and dissolution by XPS and ICP-MS were consistent with the polarization curves.     

Cyclamate intake and cyclohexylamine excretion are not related to male fertility in humans

Cyclamate and its metabolite cyclohexylamine affect male fertility in high dose animal studies, but this affect has not been investigated in epidemiological studies. This paper reports the first epidemiological study designed to investigate the possibility of a relationship between cyclamate and cyclohexylamine and male fertility in humans, in which 405 cases of clinically defined infertility in men and 379 controls were surveyed. Semen evaluation, urine analysis for cyclamate and cyclohexylamine and dietary questionnaires were compared between cases and controls. No evidence was found of a significant association between cyclamate intake and male infertility; neither high cyclamate nor high cyclohexylamine excretion were associated with elevated risk. The lack of association remained after adjusting by age, area of residence, education, total energy intake and other variables. No significant correlations were observed between cyclamate intake, metabolism or excretion, and sperm count and motility. The results demonstrate no effect of cyclamate or cyclohexylamine on male fertility at the present levels of cyclamate consumption.     

高炉冷却壁失效原因研究

本文针对安钢高炉冷却壁破损的形式、原因进行研究分析,探讨了冷却壁的结构、材质、加工与安装工艺对其寿命的影响。介绍了安钢高炉炉役后期冷却壁的维护生产实践。     

加氢反应器内构件—急冷箱的试验研究

急冷箱是加氢反应器的重要内件。洛阳石化工程公司设备研究所在认真分析UOP急冷箱的基础上,对其结构进行了改进,开发出了新型急冷箱(已获专利)。经过流体力学、传质、传热性能对比试验、分析,新型急冷箱结构性能优良。