Overexpression, purification, and characterization of SHPTP1, a Src homology 2-containing protein-tyrosine-phosphatase

A protein-tyrosine-phosphatase (PTPase; EC 3.1.3.48) containing two Src homology 2 (SH2) domains, SHPTP1, was previously identified in hematopoietic and epithelial cells. By placing the coding sequence of the PTPase behind a bacteriophage T7 promoter, we have overexpressed both the full-length enzyme and a truncated PTPase domain in Escherichia coli. In each case, the soluble enzyme was expressed at levels of 3-4% of total soluble E. coli protein. The recombinant proteins had molecular weights of 63,000 and 45,000 for the full-length protein and the truncated PTPase domain, respectively, as determined by SDS/PAGE. The recombinant enzymes dephosphorylated p-nitrophenyl phosphate, phosphotyrosine, and phosphotyrosyl peptides but not phosphoserine, phosphothreonine, or phosphoseryl peptides. The enzymes showed a strong dependence on pH and ionic strength for their activity, with pH optima of 5.5 and 6.3 for the full-length enzyme and the catalytic domain, respectively, and an optimal NaCl concentration of 250-300 mM. The recombinant PTPases had high Km values for p-nitrophenyl phosphate and exhibited non-Michaelis-Menten kinetics for phosphotyrosyl peptides.     

n-Al2O3/Ni复合镀层的组织与滑动磨损性能研究

用电刷镀技术制得了镍基n-Al2O3复合镀层，并对镀层的滑动磨损性能进行了试验研究。纳米复合镀层的表面形貌比较细腻，镀层中纳米粒子分布均匀，与基质金属结合紧密。镀层显微硬度达到HV700，比快速镍镀层提高约40％。滑动磨损试验结果表明，随着纳米粒子含量的增大，镀层的耐磨性提高，摩擦系数也呈增大趋势；但当镀层中n-Al2O3粒子的超过2.56%(质量分数）时，镀层的耐磨性显著下降。纳米复合镀层的磨损机制以疲劳磨损为主，而快速镍底层以粘着磨损为主。     

产品数据管理系统数据库设计

工程数据库EDB（Engineering Database），是工程设计及制造领域中相互有关的数据所组成的集合，本文在详细分析工程数据库的特点及其实现方式的基础上，结合SF－PDM数据库设计，深入讨论了使用UML进行数据库概念设计和逻辑设计的方法与步骤，总结介绍了SF－PDM数据库物理设计的思路与相关实现过程。     

我的家

我生于东京的银座,那是个靠近传统花街柳巷、歌舞升平的地方,在童年的记忆里那里随时随地都是一片华美景象。而在这些景象的背后有一排排美丽的临街二层长屋建筑,大都是料亭,还有颇有风致的砖结构剧场。那时父母在这里经营着咖啡馆,街上的行人总是把店里挤得满满的。数年前父亲     

轴齿轮断齿失效分析

通过对轴齿轮断口形貌、硬度测试及金相组织等试验进行分析表明，齿根处没有进行硬化处理造成齿根处抗疲劳性能不足是导致轴齿轮疲劳断裂的主要原因，另外齿根过渡处倒角过小，且存在纵向刀痕引起了较大应力集中也是导致轴齿轮疲劳断裂的原因。     

不同体细胞数原料乳对契达干酪成熟过程中蛋白水解的影响

为探讨原料乳中体细胞数(SCC)对契达干酪成熟过程中蛋白质水解的影响,选择SCC分别是5.6×104(LSCC)、48.8×104(MSCC)、476.1(HSCC)×104 个/mL的原料乳制作契达(cheddar)干酪,得到LSCC、MSCC、HSCC组干酪,并对各组干酪成熟过程中蛋白质水解的各项指标进行了测定.结果显示3组干酪成熟过程中蛋白的水解产物不同,LSCC组干酪品质更好.     

New concept of surface modification to LiCoO2

As the continuance of our series study on LiCoO₂ surface modification, the complicated traditional surface coating method is replaced with simple addition of amorphous YPO₄ and Al₂O₃ in commercial LiCoO₂ or in commercial electrolyte based on our understanding to the improvement mechanism of surface modification. Comprehensive studies by X-ray photoelectron spectroscopy (XPS), gas chromatography and mass spectroscopy (GC–MS), inductively coupled plasma (ICP) and Fourier transformed infrared (FTIR) indicate that the products of spontaneous reaction between the additive and the LiPF₆ based electrolyte are responsible for the performance improvements.     

On the coherent interference suppression using a spatiallysmoothing adaptive array

The behavior of a spatially smoothing adaptive array is examined. An expression for the weight vector is first derived. Using the array gain on the desired signal and the coherent interference is obtained. Then the expression for output signal-to-noise (SNR) is derived. It shows that the performance of the spatially smoothing array depends on the number of the subarrays, the angle separation, relative power and initial phase difference between the desired signal and the coherent interference. For good interference suppression it is found that the magnitude of the phase difference of the incident and interference signals must be greater than the beamwidths of both the subarray and the equivalent array. There is also a tradeoff between increasing the groups of subarrays and decreasing the number of elements in the subarrays. Computer simulation results are given that validate the analysis     

矿用圆环链弯曲点的角度分布

矿用圆环链弯曲点是应力集中点 ,肩部断裂发生于该点附近 .以 2 6× 92矿用圆环链为研究对象 ,应用方向数据统计导出该点的角度分布 ,并给出了批量检验矿用圆环链尺寸匹配状况的一种方法     

基于图像数据库的动态场景生成系统

实现各类目标和背景下动态场景的计算机编辑和生成，首先应对组成动态场景的要素进行分析，即目标，目标运动规律和特殊事件四个要素，然后通过编程由四个模块完成相应功能。目标，背景编辑模块可对目标，背景图像进行各种处理，并对重要特征量进行计算，运动路径模块可指定目标的运行规律，包括路线，大小和角度变化等。特殊事件模块可加入独立目标的各类典型事件，如运动的干扰物等。最后通过动态场景合成由计算机自动生成所需的动态场景图像。所需的原始目标，背景图像来源于图像数据库管理系统，通过索引项可便携地找到。