关于脂肪酸GC及GC-MS定性的问题？待分析样品：淡水鱼肌肉 脂肪酸 组成；文献中采用FID检测器进行检测，并用了sigma的混标进行定性。请问如何得知混标中37种 脂肪酸甲酯 的出峰时间呢？小弟的柱子是DB-5??下附文献及标品网址Approximately 50–100 mg lipids were then used for lipid class determinations by gas chromatography. Fatty acid methyl esters (FAME) were prepared by transesterification with borontrifluoride (BF3) in methanol at 70 °C. FAME was run on an Shimadzu GC-2010 gas chromatograph equipped with aflame ionization detector, a fused silica capillary column (30 m × 0.25 mm ID × 0.3 μm film, FFAP, Dalian Institute of Chemical Physics Chinese Academy of Sciences) and GC solution software. Hydrogen was used as the carrier gas (flow velocity: 1.0 ml min? 1). The injector temperature was adjusted to 260 °C, and the column temperature was increased from 160 °C to 230 °C at a rate of 2.0 °C min? 1 and then held at 230 °C for 15 min. The detector was maintained at 230 °C. The identifications of fatty acids were based on comparisons of retention times with known FAME standard mixtures (a 37-component FAME mix and menhaden oil, Sigma, Chemical Co, USA).标品网址：http://www.sigmaaldrich.com/cata ... ng=zh®ion=CN查看更多5个回答 . 24人已关注
如何选择Mott-Schottky曲线电位范围？谢谢！？各位大侠，朋友最近刚刚接触Mott-Schottky曲线，其中有多处不明白的地方，困扰许久，特来求助各位大侠，还望不吝指点，谢谢啦！麻烦了！? ?? ? 具体问题如下：? ???（1） 测试 M-S曲线时，电位范围该如何选择？（我的是一种新物质，无文献参考）电位不同是不是对Efb有很大影响？? ???（2）测试时，曲线最低点即起峰位点对应的纵坐标不为零，这样可以吗？（如图）? ???（3）根据M-S曲线测试得到的Efb位点与由线性扫描得到的起峰位点不同，该怎样解释呢？有文献解释为The discrepancy betweenVFB and the photocurrent onset is likely due to OER overpotential losses and voltage drops in the circuit. 我的是HER也可以这样解释吗？? ?? ? 谢谢诸位！万分感谢！未标题-2 拷贝.jpg查看更多6个回答 . 2人已关注
如何实现乙醇/氦气的混合气，因为乙醇为液体，需要单独给乙醇加热形成蒸汽吗?如题Some article says ethanol adsorption was carried out for 30 min using a 2.0% ethanol/He gas mixture (1.0 mL/s), as we know, ethanol is liquid, how to realize the gas mixture of ethanol and helium, and guarantee the volume fraction of 2%.Is the gas mixture in the cylinder together or??with the help of flowmeter?many thanks for help.查看更多2个回答 . 10人已关注
斯坦福大学崔毅再发牛文：半液态锂硫电池？此技术已经被MIT Technology Review网站高调报导http://www.technologyreview.com/ ... -store-solar-power/AbstractLarge-scale energy storage represents a key challenge for renewable energy and new systems with low cost, high energy density and long cycle life are desired. In this article, we develop a new lithium/polysulfide (Li/PS) semi-liquid battery for large-scale energy storage, with lithium polysulfide (Li2S8) in ether solvent as a catholyte and metallic lithium as an anode. Unlike previous work on Li/S batteries with discharge products such as solid state Li2S2 and Li2S, the catholyte is designed to cycle only in the range between sulfur and Li2S4. Consequently all detrimental effects due to the formation and volume expansion of solid Li2S2/Li2S are avoided. This novel strategy results in excellent cycle life and compatibility with flow battery design. The proof-of-concept Li/PS battery could reach a high energy density of 170 W h kg?1 and 190 W h L?1 for large scale storage at the solubility limit, while keeping the advantages of hybrid flow batteries. We demonstrated that, with a 5 M Li2S8 catholyte, energy densities of 97 W h kg?1 and 108 W h L?1 can be achieved. As the lithium surface is well passivated by LiNO3 additive in ether solvent, internal shuttle effect is largely eliminated and thus excellent performance over 2000 cycles is achieved with a constant capacity of 200 mA h g?1. This new system can operate without the expensive ion-selective membrane, and it is attractive for large-scale energy storage.GA.gifflow.batteryx299.jpg查看更多0个回答 . 15人已关注
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