铸渗质量及其影响因素评述

文章以铸渗法改善零件表面性能为基础，评述分析了近年来的研究成果，归纳总结了影响铸渗质量的几个主要因素，为铸渗工艺今后的发展指明了方向。     

压水堆一回路模拟腐蚀氧化物的溶解去污试验

本文介绍了对两种压水反应堆一回路模拟腐蚀氧化物（铁镍铬氧化物和铁镍氧化物）的溶解去污试验结果。选择的去污剂为0.3%草酸、0.1%柠檬酸和0.1%高锰酸钾。结果表明，实验温度为95℃、去污时间在6－48h范围内，0.3%草酸对铁镍铬氧化物和铁镍氧化物的溶解率分别为24.1%-65.3%和4.9%-64.4%；0.1%柠檬酸对二者的溶解率分别为2.2%-4.4%和0.37%-1.55%；0.1%高锰酸钾对二者几乎没有溶解作用。采用在草酸或柠檬酸去污前使用高锰酸钾去污剂的二步去污法，对两种氧化物的溶解度小于单独使用草酸或柠檬酸去污的一步法。     

射线诱导的细胞凋亡过程中端粒酶表达及其活性

利用原位端粒酶-凋亡双染色法检测A549细胞和L02细胞hTERT和凋亡双表达，端粒序列扩增检测(TRAP)方法检测群体细胞端粒酶活性，研究γ射线照射人肿瘤细胞和正常细胞后端粒酶的表达变化与凋亡-发生的关系。结果表明，1—SGy照射后24—72h，A549细胞和L02细胞内hTERT表达增强，端粒酶和凋亡双染色阳性细胞随照射剂量的提高而增多；在凋亡发生的过程中，群体细胞端粒酶活性呈剂量依赖性增强，提示放射线诱导人肿瘤和正常细胞凋亡可能不是通过直接抑制端粒酶活性的机制；而辐射诱导端粒酶活性增高可能是细胞修复辐射损伤的机制之一。     

The hydration characteristics and expansion machanism of expansive cement at low<Emphasis Type="Italic">W/B</Emphasis> ratio

The hydration characteristics and expansion impetus of three kinds of cement paste under free-and confined-curing conditions were investigated, which were respectively mixed with three different kinds of expansive agent at low W/B ratio. The results show that the hydration products of pure cement paste and paste mixed with expansive agent are same, but the amount of hydration products, un-hydrated C₃S and C₂S are obviously different at the same hydration age. At 3 d age, the amount of CH in pure cement paste is less than that of paste mixed with expansive agent, but it is reverse when at 28 d age. The amount of AFt at 3d and 28d age in pure cement paste is less than those of paste mixed with expansive agent. Regardless of under free- or confined-curing condition, the amount of ettringite produced varies little since 3d age. The joint effect of the tumefaction of gel-ettringite due to water absorption and the expansive pressure on the pore caused by the crystalloid ettringite is the cause of the volume expansion of cement paste, and the former effect is much greater than the latter. LU Lin-nu : Born in 1972 Funded by 973 High-tech Project of China (No. 2001CB610704-2) and the Natural Science Foundation of Hubei Province(No. 2002AB075)     

A New Grade Carbon Black Produced by Thermal Plasma Process

This paper presents a new route about producing carbon black,by wich the natural gas cracking is carried out in the absence of oxygen thanks to an electric energy supply externally given by a plasma jet.The carbon black produced by this process has a narrow size distribution and a small average diameter of 38nm as well as a highly branched aggregate.The higher DBP value of 1.40ml/g shows it should be a high structure carbon black.The FTIR spectra shows that there are lots of aromatic c-c bonds and a large amount of nitrogen-coutaining functional groups on the carbon blacks surface,such as-NH,-CN as we3ll as -CH,-OH,-COOH groups.     

The Tb Doping Effect on the Room Temperature Magnetoresistance in(La_(1-x)Tb_x)_(0.67)Sr_(0.33)MnO_3(x≤0.4)

With substitution of La by Tb in (La_(1-x)Tb_x)_(0.67)Sr_(0.33)MnO_3, the room temperature magnetoresistance △R/R_0drops at first, then undergoes an increase near x≈0.1, and finally drops again. The value of room temperaturemagnetoresistance at a field H=12 kOe for (La_(0.9)Tb_(0.1))_(0.67)Sr_(0.33)MnO_3 is -3.56%. The enhancement of the roomtemperature magnetoresistance induced by an appropriate Tb substitution in (La_(1-x)Tb_x)_(0.67)Sr_(0.33)MnO_3 is correlatedwith the shifts of the Curie temperature and metal-insulator temperature to near room temperature. The drop ofthe room temperature magnetoresistance at large Tb doping-contents may be due to its lower T_C and T_(MI) far fromthe room temperature.     

用于海水反渗透淡化系统的能量回收器的实验研究

介绍了用于海水反渗透淡化系统的余压能量回收器的工作原理，建立了相应的实验装置，研究了能量回收器工作流体的流量和压力的变化规律，分析了其中的变化原因，为今后能量回收器的设计和优化提供可靠的依据．     

钴溶液除铁的工艺改进

对钴渣溶解后液原使用的中和法除铁的情况和采用黄钠铁矾法除铁后的现状进行了对比分析，介绍了采用黄钠铁矾法除铁后，金属回收率、辅材消耗量等项指标有明显改善，提高了经济效益。     

球内凝固过程的近似解分析

对球内凝固相变过程作了较为系统和全面的理论分析 ,建立了能够揭示在第三类边界条件下球体内相变传热过程物理机制的数学模型 ,用Lighthill奇异摄动法给出了球体内对称凝固问题的近似分析解 ,并以Ba(OH) 2 ·8H2 O为相变材料 ,得到了相变界面、相变介质温度随时间和热流密度随相变位置的变化规律 ,以及球囊半径和对流换热系数对凝固过程的影响。得到结论 :对一般工程背景 ,球囊半径为 1 .5～ 2 .0cm ,h <1 0 0 0W /(m2 ·K)较为合适 ,从而为以球为相变贮能单元的贮能装置的优化设计提供了一定的理论参考。     

ZnO导电陶瓷的制备及电性能研究

采用注浆成型法制得ZnO导电陶瓷 ,通过添加Al2 O3、Cr2 O3、Fe2 O3、La2 O3,探讨了各添加剂对ZnO陶瓷电性能的影响。结果表明 ,聚丙烯酸胺 (PMMA)是ZnO粉体良好的分散剂 ,其质量分数在 0 3%时可得到低粘度、高固含量的ZnO悬浮体。各种氧化物添加剂的添加量对ZnO陶瓷的室温电阻率及电阻温度特性具有较大的影响。随着Al2 O3添加量的增加 ,ZnO陶瓷体的电阻率先略微减小然后增大 ;添加Cr2 O3与添加Al2 O3的效果相反 ;随着Fe2 O3、La2 O3添加量的增加 ,ZnO陶瓷体的电阻率增大。添加Al2 O3、Cr2 O3、Fe2 O3、La2O3的ZnO陶瓷呈现负电阻温度特性。