分瓶法测定果蝇吸入麻醉药半数麻醉有效浓度

目的 建立测定果蝇吸入麻醉药半数麻醉有效浓度 (ED50 )的方法学。方法 在 11个 32 5ml的三角烧瓶中各放入 30只雄性果蝇 ,分别加入不同容量的异氟醚标准气 ,使 11个烧瓶中异氟醚浓度分布在零效应浓度与百分之百效应浓度之间。以果蝇失去附壁及运动能力为标准计算各瓶中被麻醉果蝇数 ,用正规法计算出ED50 。结果 11次实验在 2 5及 5 0min时的量 -效关系曲线均呈S形 ,用各自的对数浓度与概率单位作图都呈直线相关 ,相关系数分别为 0 .972± 0 .0 14和 0 .971± 0 .0 2 5 ,ED50 值分别为 (0 .5 1± 0 .0 6 8) %和 (0 .4 7± 0 .0 85 ) % ,变异系数分别为 13.3%和 18.0 %。结论 本法稳定性较好 。

Measurement and engineering application of adsorbed water content in fine-grained soils

In this paper,the content and density of adsorbed water in fine-grained soil are determined.According to the test results,the calculation method of compaction degree of the solid-phase and void ration of soil is improved.Four kinds of fine-grained soils from different regions in China were selected,and the adsorbed water content and density of four kinds of fine-grained soils were determined by thermogravimetry and volumetric flask method.Furthermore,SEM and XRD experiments were used to analyze the differences in the ability of each soil sample to absorb water.In order to study the compression characteristics of adsorbed water,four saturated soil samples were tested by consolidation method.The results show that the desorption temperature range of the adsorbed water and its density were equal to 100−115℃and 1.30 g/cm^(3),respectively.Adsorbed water plays a positive role in keeping the compressibility of fine-grained soil at a low rate when it has high water content.Besides,adsorbed water can be a stable parameter and is difficult to discharge during the operation period of subgrade.The settlement of fine-grained soil embankment is predicted by engineering example,and compared with the result of conventional calculation method.The results show that it is more close to the field monitoring results by using the improved void ratio of soil as the parameter.

Homemade versus Commercial Jarred Baby Foods with Regard to Nitrites and Nitrates Content

This paper presents results of nitrites and nitrates determination in two types of baby foods： commercial products in jars and their homemade conventional counterparts. Nitrites levels in all analyzed samples were below of the detection limit （〈 0.9 mg/kg） of applied spectrophotometric method with Griess reagent. Nitrates contents in commercial products ranged： 9.1-38.1 mg/kg while in homemade baby foods levels between 26.6 mg/kg and 118.8 mg/kg were obtained. All the contents of nitrates were lower than the EU legislation maximum limit （200 mg/kg）. Comparison of each type of commercial product with its homemade counterpart baby food evidenced significant differences （p 〈 0.05） in average nitrates levels in favor of the first type. Apart from determining and comparing the levels of nitrates in the baby food samples also risk assessment for an average 6-months old infant to nitrates exposure was conducted. The estimated nitrates intake with a typical portion of 200g of baby food ranged between 6% and 25.7% of acceptable daily intake for commercial and from 18.0% to 80.3% for homemade ones.

温度和pH对儿茶素萃取平衡的影响

采用摇瓶-分光光度法测定不同温度和不同pH值下茶多酚在乙酸乙酯/水中的分配系数。结果表明,温度和pH对儿茶素在萃取体系中的分配系数有显著影响,温度为285.13K和pH4.6时茶多酚在乙酸乙酯中的分配系数为6.976,是313.15K和pH6.0时的2.23倍,因此低温和pH4.6环境有利于茶多酚的萃取。