一种新颖的测定分子间势能及普适气体常量R的热学实验装置设计

设计了一种简单的实验装置,可同时测量分子间相互作用的势能和普适气体常量R。其实验曲线符合理论值,误差分析后的补偿曲线所得结果可较为精确地与理论结果吻合。该实验常温下即可进行,且精度较高。该装置可用于课堂教学,有利于学生对热学问题的深入理解。     

Response to weaning and dietary L-glutamine supplementation: metabolomic analysis in piglets by gas chromatography/mass spectrometry

A novel metabolomic method based on gas chromatography/mass spectrometry (GC-MS) was applied to determine the metabolites in the serum of piglets in response to weaning and dietary L-glutamine (Gln) supplementation. Thirty-six 21-d-old piglets were randomly assigned into three groups. One group continued to suckle from the sows (suckling group), whereas the other two groups were weaned and their diets were supplemented with 1% (w/w) Gln or isonitrogenous L-alanine, respectively, representing Gln group or control group. Serum samples were collected to characterize metabolites after a 7-d treatment. Results showed that twenty metabolites were down-regulated significantly (P<0.05) in control piglets compared with suckling ones. These data demonstrated that early weaning causes a wide range of metabolic changes across arginine and proline metabolism, aminosugar and nucleotide metabolism, galactose metabolism, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acid, and fatty acid metabolism. Dietary Gln supplementation increased the levels of creatinine, D-xylose, 2-hydroxybutyric acid, palmitelaidic acid, and α-L-galactofuranose (P<0.05) in early weaned piglets, and were involved in the arginine and proline metabolism, carbohydrate metabolism, and fatty acid metabolism. A leave-one-out cross-validation of random forest analysis indicated that creatinine was the most important metabolite among the three groups. Notably, the concentration of creatinine in control piglets was decreased (P=0.00001) compared to the suckling piglets, and increased (P=0.0003) in Gln-supplemented piglets. A correlation network for weaned and suckling piglets revealed that early weaning changed the metabolic pathways, leading to the abnormality of carbohydrate metabolism, amino acid metabolism, and lipid metabolism, which could be partially improved by dietary Gln supplementation. These findings provide fresh insight into the complex metabolic changes in response to early weaning and dietary Gln supplementation in piglets.     

甘肃陇南产植物苍耳茎叶挥发油成分分析

采用水蒸气蒸馏法提取苍耳挥发油,并用气相质谱联用技术对挥发油的化学成分进行了分析,共分离鉴定出95个化合物,其主要成分为烷类、倍半萜内酯及醛酮类等.     

气相色谱仪检定装置不确定度评定

测量不确定度是与测量结果相关、表示被测量的量值分散性的参数,它是评定被测量的真值所处范围的一个参数。根据JJG700-1999《气相色谱仪检定规程》,按照不确定度评定原则,对一套气相色谱检定装置进行不确定度评定。     

双甲胺草磷的气相色谱分析

探讨了除草剂双甲胺草磷的气相色谱分析方法,并对该分析方法进行了精密度和准确度的实验测定。结果表明,其标准偏差为0.32%,变异系数为0.33%,回收率为99.72%。     

顶空气相色谱法测定化妆品中甲醇

本文采用顶空气相色谱法测定化妆品中甲醇的含量。用氢火焰离子化检测器检测，化妆品中甲醇的最低检测浓度为1．5mg／kg，在样品中加标量分别为20mg和40mg时，回收率为91．9％-95．2％，依本法取两份样品分别测6次，变异系数为1．6％-2．8％。     

罗布麻叶挥发油的提取与气相色谱-质谱分析

用同时蒸馏装置萃取了罗布麻叶中挥发油，测得提取率为1．51％．并采用气相色谱-质谱联用技术对罗布麻的挥发性成分进行了分离鉴定．分离出37种成分，占挥发油总含量的97．83％．采用峰面积归一化法确定了各成分的相对含量，其中主要成分为：双烯桉叶（17．10％），薄荷醇（7．03％），5，6，7，7a-四氢化4，4，7a-三甲基-2（4H）苯并呋喃（6．64％），三甲基-8-亚甲基-十氢化4-亚甲基萘醇（5．25％），氧化石竹烯（3．94％）．     

毛细管气相色谱质谱法分析茉莉花中挥发性化学成分

报道了用同时蒸馏萃取装置(SDE)提取茉莉花的挥发性物质,测得茉莉花挥发油含量为5.35%,用毛细管气相色谱质谱法从茉莉花的挥发油中分离确认出48种化学成分.用峰面积归一化法通过化学工作站数据处理系统得出各化学成分在挥发油中的百分含量,测得其占总检出量的98.38%..     

关于如何将信息技术应用于《油气地球化学》教学的思考

教学信息化是高校专业课教学的趋势,以《油气地球化学》课程为例,论述了实现专业课信息化教学的途径:首先要把握教学信息化的目的和要求,即拓展学生获取专业知识空间和手段,锻炼学生融合各种相关知识的能力,以提高学生掌握知识的效率;然后结合专业课程的特点,建成立体的网络教学资源库,引导学生充分利用网络教学平台,高效掌握并学会应用专业知识。     

Numerical forecasting surge in a piping of compressor shops of gas pipeline network

This paper presents a method of forecasting stable operation of gas compressor unit (GCU) centrifugal supercharger (CFS) installed on a piping of compressor shops servicing gas pipelines. The stability of superchargers operation is assessed in relation to the phenomenon of surge. Solution of this problem amounts to the development and numerical analysis of a set of ordinary differential equations. The set describes transmission of gas through a compressor shop as a fluid dynamics model with lumped parameters. The proposed method is oriented to wide application by specialists working in the gas industry. The practical application of this method can use all-purpose programming and mathematical software available to specialists of gas companies.