Slag resistance mechanism of CaO·6Al2O3 refractory and its effect on inclusions of aluminum deoxidized steel

In order to verify the advantage of CaO·6Al₂O₃ (CA₆)-based refractories on the inclusions of aluminum deoxidized steel, the five refractories, CA₆, alumina, spinel, and CA₆-alumina and CA₆-spinel composition refractories were prepared into crucibles, and then the laboratory smelting experiments were conducted. After experiment, the slag resistance of the crucible and the variation on inclusions in steel were characterized and discussed. A dense CaO·2Al₂O₃ (CA₂) layer, which was produced by CA₆ reacting with the slag, was distributed between the original bricklayer and the slag layer, improving the slag resistance of refractories. Meanwhile, the 12CaO·7Al₂O₃ (C₁₂A₇), generated by the reaction between CA₂ and refining slag, would release much Ca into the molten steel. The Ca would react with inclusions to produce low melting point substance to float up and remove, contributing to the reduction of the proportion of large size inclusions. In addition, typical inclusions in steel smelted with CA₆ crucible were small-sized MgO·Al₂O₃ inclusions, whereas those of other crucibles are MnS–MgO·Al₂O₃ composite inclusions with MgO·Al₂O₃ as the core, implying CA₆ may absorb sulfur during the smelting process.     

低碳钢丝焊网热镀锌工艺的改进

根据低碳钢热镀锌原理,指出低碳钢丝焊网热镀锌工艺存在的主要问题是工艺不完善、锌液成分不合理、镀后抹拭材料及方法不当等。采用复合除锈剂强化除锈效果,用氯化锌与氯化铵质量比为1.2~1.6的混合溶液代替单一的氯化铵作为助镀剂,增加助镀后烘干工序,采用无机物和珍珠岩混合材料作为抹拭剂等改进措施,使镀锌层表面光滑,焊接位置无积锌,锌耗比改进前降低2%。     

Poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes for the electrochemical detection of copper(II)

Poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes obtained by electropolymerization of 2-amino-4-thiazoleacetic acid, were used for the voltammetric determination of copper ions. The voltammetric response of copper ions at poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes was evaluated by differential pulse stripping voltammetry. The peak currents were linearly dependent on the concentrations of the copper ions in the range from 7.0 × 10⁻⁷ M to 5.0 × 10⁻⁵ M, with a coefficiency of 0.9987. The detection limit is 5.0 × 10⁻¹⁰ M calculated for a signal-to-noise ratio of 3 (S/N = 3). And it could be used for the simultaneous determination of copper and cadmium ions. The proposed method was successfully applied to the determination of copper ions in natural water. The concentration of Cu²⁺ was calculated to be 2.0 × 10⁻⁵ M by standard addition method. The recovery rate was 94%.     

网络应用综合检测系统的研究

针对分布式应用系统的运行维护难题,提出一个网络应用综合检测方案,采用网络检测与应用检测取长补短相互结合的新方法,借助多线程技术,对分布的跨平台应用服务器、业务数据库和异构应用组件的实时运行状态,进行全自动高效检测、分析和预警。该方案通过在上海大学房产地图应用系统检测的实例验证,取得较好效果。     

褐藻胶酸降解物α-葡萄糖苷酶的抑制活性

褐藻胶作为海洋植物提取物,近年来受到开发海洋类药物的研究人员关注。有报道称褐藻胶降解物具有治愈Ⅱ型糖尿病鼠的功效。基于此,本研究通过体外α-葡萄糖苷酶体系来探讨褐藻酸降解物的降血糖机制。结果表明:聚甘露糖醛酸片段(PM)和聚古洛糖醛酸片段(PG)对α-葡萄糖苷酶的活性均产生抑制作用,且其活性差异较大。其中具有明显抑制作用的PM的抑制类型属于混合型抑制,其抑制常数Ki和抑制率的IC50值仅分别为葡萄糖的4.4倍和7.0倍。通过比较PM、葡萄糖、甘露糖、果糖的Ki值和IC50值的差异,从构效关系上探讨α-葡萄糖苷酶与α-葡萄糖苷酶抑制剂的关系。     

高精度光栅测长机校准及不确定度分析

本文论述了测长机和测长仪的区别,高精度光栅测长机应归于测长仪类,适用于JJF 1189-2008《测长仪校准规范》.校准高精度光栅测长机,需严格控制环境温度,测量小尺寸量块需考虑两球形测头不同心引入的误差,测量内尺寸以两环规直径差作为标准值,测得值可用平均值代替最大值,分析了二等量块校准光栅测长机外尺寸示值误差的测量不...     

复合模板剂诱导合成SAPO-34分子筛及其MTO性能研究

利用传统水热合成方法,分别采用单一模板剂、混合模板剂合成纯相SAPO-34分子筛,采用XRD、BET、SEM、NH3-TPD和FTIR对样品进行表征,考察其在甲醇制烯烃反应中的催化性能。结果表明,混合模板剂诱导合成的SAPO-34分子筛具有较小的颗粒尺寸,较大的比表面积和适宜的酸性,可以在MTO反应中表现出更优的催化性能。结果发现,MORTEAOH混合模板剂合成的SAPO-34分子筛的催化寿命达320 min,双烯选择性超过82%。     

模具参数对旋转通道等径角平行挤压工艺的影响

为克服传统等径角挤压反复多道次累积塑性变形带来多次装料、多次加载以及棒料机械加工等耗时问题,无损伤地制备均匀超细晶结构时效硬化型铝合金,提出旋转通道等径角平行挤压大塑性变形新工艺。该工艺在一个通道内设置多个剪切变形区,通过在两个等径角挤压通道之间设置旋转通道来改变圆棒料剪切方向和剪切角度,实现Bc加工路径,提高变形均匀性。采用正交试验法选取内角Φ、外角Ψ、升角γ、椭圆因子m、第2个通道中第1段直通道长度L_1作为因素,采用有限元模拟法对棒料在16组不同水平的模具中进行有限元挤压模拟。以等效应变、等效应力、损伤量以及变形均匀性系数作为指标值分析其对挤压过程的影响。模拟实验结果表明,良好的挤压通道内角Φ的合理范围为90°~120°,外角Ψ的合理范围为30°~40°,升角γ的合理范围为60°~80°,m的合理范围为1.2~1.4,L_1、L_3的合理范围为(1~1.5)d。     

Novel B-site scheelite structure ceramic Bi(Ge0.5Mo0.5)O4 and its dielectric properties

Scheelite structure phase inorganic oxides show their irreplaceable role in numerous application areas due to their clear structure and superior properties, especially in dielectrics. Scheelite structure phase BiVO₄ has been permanently studied but substitutions, modifications, and explorations of novel phases persist hitherto and inspire more interest. In this work, we report a novel Scheelite structure phase of Bi(Ge_0.5Mo_0.5)O₄ and a detailed study of both structural analysis and dielectric properties investigation. Bi(Ge_0.5Mo_0.5)O₄ adopts the monoclinic Scheelite structure, identical to BiVO₄, with a dielectric permittivity of ∼ 35, Qf value of ∼20 000 GHz, and TCF value of ‒46 ppm/°C. No secondary ferroelastic transition was seen in Bi(Ge_0.5Mo_0.5)O₄ till 600°C, close to its synthetical temperature. The results indicate the success of discovering a new Scheelite structure phase and its prior engineering potential in modifying and substituting BiVO₄ over the dielectric area, photocatalyst, ion conductor, and so forth.