Investigation on interior moisture distribution inducing dielectric anisotropy of coals

Dielectric anisotropy phenomenon of coal was detectable by many dielectric measurements. The paper presented that it was attributed to coal interior moisture distribution. A new model describing interior moisture distribution was developed basing on microstructure observation of coal. In the model, coal interior moisture distribution was analyzed and simulated numerically, the relationship between interior moisture distribution and coal dielectric property was constructed, the character of the permittivity varying with moisture content had also been studied and coal dielectric anisotropy was deduced. Corresponding experiment results were well satisfied with the model analysis, demonstrating that the interior moisture content could cause coal dielectric anisotropy.     

Studies of substrate specificities of lipases from different sources

Although lipases are widely applied in a wide variety of reactions, available information on the factors that are responsible for the substrate specificities of lipases from different sources is scarce. In this paper, nine lipase‐producing microorganism strains were isolated from oil‐containing samples. The properties of these enzymes, including pH optima, temperature optima, thermal stability, and pH stability, vary significantly with the different sources from which these lipases were isolated. The substrate specificities of the nine lipases, including fatty acid and positional specificities, were also studied. The fatty acid specificities of the nine lipases were observably different toward 15 substrates with different carbon chain lengths, different saturation degrees and different side chains. The lipases from S₃ Penicillium citrinum (PCL), MJ₁ Aspergillus niger (ANL), MJ₂ Aspergillus oryzae (AOL), YM Bacillus coughing (BCL), S₉ Geotrichum candidum (GCL), and S₁₁ Candida lypolytica (CLL) showed the strongest specificities to short‐chain esters, and the other lipases showed strong selectivity for medium‐ or long‐chain and branched esters. The positional specificities were examined by analyzing the hydrolytic products of triolein catalyzed by the nine lipases, using TLC. The lipases can be mainly classified into two groups by their specificities for the ester bond at position 2 of triglycerides; one group can selectively hydrolyze the ester bond at position 2 of the triglycerides, the other group cannot. All these nine lipases were divided into four groups by hierarchical clustering analysis on the basis of the results of fatty acid and positional specificities.     

星型聚合物中间体环硅氧烷核的合成研究

以甲基二氯硅烷、四甲基四乙烯基环四硅氧烷(DVi4)为原料,采用硅氢加成反应合成了星型聚合物的中问体环硅氧烷核,并用红外光谱和核磁共振谱进行了表征.反应的最佳条件是:采用预先活化、反应温度72℃、催化荆与DVi4的量之比为1.0×10-4,反应转化率可达95%,且选择性很好,产物主要为β-加成产物.     

无氢类金刚石碳膜的研究进展

介绍了无氢类金刚石碳膜的制备方法 ,它们的机械、光学、电学性能 ,将无氢与含氢的类金刚石碳膜进行了简单比较 ,总结及探讨了它们的应用     

外浮顶油罐的液位检测仪表选型及安装

音叉式液位开关和外贴超声波液位开关具有多种优点，近年来逐步取代浮球液位开关，成为大型储罐液位检测的重要仪表。本文通过详细介绍这两种液位开关在外浮顶油罐的设计选型和具体安装，通过阐述检测原理，比较各种安装方式的优缺点，分析产生缺陷的原因以及提出解决方法，为设计施工人员进行仪表选型和安装提供重要参考意见。     

High-cycle fatigue characterization of titanium 5Al-2.5Sn alloy

High-cycle fatigue behaviour of titanium 5Al-2.5Sn alloy at room temperature has been studied. S-N curve characterization is performed at different stress ratios ranging from 0 to 0.9 on a subsized fatigue specimen. Both two-stress and three-stress level tests are conducted at different stress ratios to study the cumulative fatigue damage. Life prediction techniques of linear damage rule, double linear damage rule and damage curve approaches are applied, and results are compared with the experimental data. The agreement between prediction and experiment is found to be excellent.     

射频激励扩散型冷却阵列波导CO2激光器技术

本文介绍了目前国内外研究者们提出的各种射频激励相干阵列波导ＣＯ２激光器技术，讨论了射频激励相干阵列波导ＣＯ２激光器技术的一个研究方向。     

抽油机球铁齿轮的化学成分及生产工艺

为提高抽油机减速器齿轮铸件的机械性能，提出以Sn代替Mo作为合金元素，并通过试验确定了合理的Si、Cu、Sn的加入量。指出Si加入量应控制在1．9％－2．1％范围内，同时加入0．36％～0．9％的Cu和0．025％～0．07％的Sn，可保证球铁的强度和延伸率都满足QT700－2的要求。鉴于试件与实际铸件的表面硬度有一定的差值，为提高铸件表面硬度，进行了余热正火试验，并给出了铸件在铸型内的时间－冷却温度曲线。最后根据球铁化学成分的选择结果，进行了齿轮生产试验。     

人造导星技术及导星用激光系统

论述了自适应光学系统对人造导星的需要;简单介绍了两类激光导星;重点描述了销激光导星的产生机理及可用于销激光导星的一些激光系统.     

高灵敏度荧光显微镜及其在细胞光敏效应研究中的应用

研制了一种可探测极微弱细胞荧光图象的高灵敏度荧光显微镜，在仪器中使用了一个高质量的亮度增益为５０，０００的象增强器对细胞的荧光图象进行光能量放大，因而这种荧光显微镜可探测到普通荧光显微镜不能观察的微弱荧光图象。由于仪器中光源的输出强度很小，避免了长时间观察对活细胞的光损伤，并可观察到荧光效率低的荧光物质的分布图象。探测系统中用计算机采集图象数据，同时对数据进行必要处理，以提高图象的质量。这种高灵敏度的荧光显微镜可用于分析细胞中荧光物质的分布，以及细胞动态生理过程的研究。使用此仪器已直接观察到光敏竹红菌甲素在Ｈｅｌａ细胞（人体宫颈癌细胞）中的分布，细胞受光照射后的光损伤现象及加入三种细胞保护剂后获得不同程度保护的细胞状态。