镁合金热裂行为研究的测试方法探讨

针对镁合金的特点,就合金热裂行为研究的测试方法进行了实验研究和分析。用热裂行为测试系统测量合金凝固过程中的温度、线收缩和收缩应力,用铸造热分析系统分析铸造凝固条件下的相析出,这为研究合金的热裂形成机理提供了重要的实验手段。采用热裂环法可以有效地评价合金的热裂倾向性,而等长度试棒法(无论金属型还是砂型)则不适于测试镁合金。

Mg-Gd-Y-Zr合金的热裂性能

分别采用约束热裂棒法、热裂环法以及热裂综合测试系统来评定Mg-10Gd-3Y-Zr合金的热裂倾向性,并与常用AZ91D镁合金的热裂性能进行了比较。研究发现,Mg-10Gd-3Y-Zr合金和AZ91D合金的热裂倾向性为:约束热裂棒法评定的热裂倾向系数分别为8和32,热裂综合测试系统测定其抗热裂力分别约为340N和40N,热裂环法测定Mg-10Gd-3Y-Zr合金和AZ91D合金的临界断裂直径分别为53mm和48mm。试验结果表明,Mg-10Gd-3Y-Zr合金的热裂倾向性低于AZ91D合金的热裂倾向性。

“软割接”缩短传输网络优化业务中断时长

现有网络优化中,都是采用先屏蔽基站业务,再进行传输光链路割接,往往业务中断时间较长。本文探讨传输网络优化中引入"软割接"的思路,通过搭建过渡接入系统,将业务平滑割接至新的系统上,从而缩短优化过程中业务中断时长。

Interaction between Mitomycin C and DNA at Paraffined Graphite Electrode

Aim To investigate the electrochemical behaviors of Mitomycin C （MC） and its interaction with calf thymus DNA （ctDNA）. Methods The cyclic vohammetry （CV） was carried out at a paraffined graphite electrode. Results MC showed a well-defined oxidation-reduction peak. As a result of reaction with ctDNA, the peak current of MC decreased apparently. According to corresponding electrochemical equations, the diffusion coefficient of both free and MC-DNA complex have been determined, and the heterogeneous rate constants were also obtained simultaneously. Conclusion The solid paraffined graphite electrode could be used to estimate parameters of the interaction between DNA and MC, and provide the convenient and sensitive analysis.