凝胶HPLC测定相思子毒素纳米粒包封率

目的建立相思子毒素的凝胶HPLC分析方法,用于测定相思子毒素纳米粒的包封率。方法采用TSKgel G2000SWXL凝胶色谱柱;流动相为20mmol/L PB,pH=7.3,流速为0.8mL/min;柱温为25℃;分析时间为20min;紫外检测波长为214 nm;进样量60μL。结果 2种纳米粒上清液对于相思子毒素的测定均无干扰;相思子毒素保留时间为10.35±0.55min(n=20);在浓度范围12.5-400μg/mL内,峰面积与相思子毒素含量成良好的线性关系:y=52.85676x-342.656,R=0.9999(n=6,P<0.0001);相思子毒素日内平均回收率为100.47%-107.73%,RSD为0.17%-0.25%;日间回收率为100.87%-106.33%,RSD为1.48%-2.18%;温度对于相思子毒素含量变化影响很小,5日内,相思子毒素样品在室温、4℃以及-20℃保存均较为稳定,检测浓度平均回收率为98.04%-106.86%,RSD<3%;蛋白的最低检测限为49.5ng。结论该方法专属性强,可用于相思子毒素纳米粒包封率和释药率的测定,也可用于较低含量相思子毒素的定量分析。     

Effect of the loading mode and temperature on hydrogen embrittlement behavior of 15Cr for steam turbine last stage blade steel

The hydrogen embrittlement of 15Cr martensitic stainless steel, for steam turbine last stage blades, was systematically studied by using slow strain rate tensile (SSRT) test and constant loading tensile (CLT) test at room temperature and 80 °C to simulate the service conditions. It was shown that, despite the lower hydrogen concentration absorbed during SSRT, the hydrogen-induced fracture strength of 15Cr steel for SSRT was lower than the threshold fracture strength for CLT. This was due to the remarkable enhancement in local hydrogen concentration due to the transportation of hydrogen by mobile dislocation during SSRT. In addition, although the higher hydrogen concentration was absorbed during SSRT at 80 °C, the hydrogen embrittlement susceptibility of 15Cr steel for SSRT at 80 °C was lower than that at room temperature, because the degree of local hydrogen accumulation decreased at a higher temperature.     

Catalysts for Direct Methanol Fuel Cells

The activity of in house prepared carbon-supported Pt-Ru catalysts for methanol oxidation and carbon-supported RuSe for the oxygen reduction reaction in direct methanol fuel cells (DMFCs) was investigated. The composition of Pt-Ru/C was varied both in terms of weight loading (ratio of total metal content to carbon) as well as the ratio of Pt to Ru. The measurements were carried out in a half cell arrangement in sulphuric acid at various temperatures. The weight loading and ratio of Pt to Ru were varied in order to find out the optimum weight loading of precious metal and the temperature dependence of Pt to Ru ratio on methanol oxidation reaction. It has been found that there exists an optimum in the weight loading at 60 wt.% for carbon-supported Pt-Ru catalyst towards its maximum mass activity. While 1:1 Pt to Ru ratio exhibits a higher activity than 3:2 Pt:Ru above 60 °C, 3:2 ratio exhibits a higher activity at lower temperature. It has been observed that RuSe is inactive towards methanol and it is realised that RuSe is a potential candidate as methanol tolerant oxygen reduction catalyst. The activity of carbon supported RuSe for oxygen reduction reaction (ORR) was tested in sulphuric acid in the presence of methanol. Even though the mass specific activity of the RuSe catalyst is somewhat lower than that of Pt/C, the surface activity of carbon-supported RuSe is superior than that of carbon supported Pt which indicate the unfavourable size distribution of RuSe/C catalyst.