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101.
钨酸催化氧化环己酮合成己二酸 总被引:3,自引:1,他引:3
以钨酸-有机酸性添加剂为催化体系,在无有机溶剂和相转移剂的情况下,催化30%过氧化氢氧化环己酮合成己二酸。当钨酸∶有机酸性添加剂∶环己酮∶过氧化氢=11∶4∶01∶76(摩尔比,钨酸用量为2.5mmol)时,使用有机酸性添加剂来调节钨酸催化活性,结果表明以钨酸-磺酸水杨酸氧化环己酮效果最优,反应8h时己二酸分离产率达86.8%、纯度为99.9%;以间苯二酚或邻苯二酚为添加剂时,己二酸分离产率分别达到85.9%和84.5%,纯度约为100%;而不使用任何添加剂时,己二酸分离产率只有68.1%、纯度为95.2%。当使用磺酸水杨酸、草酸等为有机酸性添加剂时,随反应时间的延长,己二酸分离产率均升高。当磺酸水杨酸用量为2.5mmol时,己二酸分离产率和纯度均较高。钨酸-磺酸水杨酸和钨酸-草酸催化体系重复使用5次后,己二酸分离产率仍分别可达80.2%和80.9%。 相似文献
102.
M Harmsen TA Oosterlaken C Tangerman H Snippe CA Kraaijeveld 《Canadian Metallurgical Quarterly》1993,43(2):137-146
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (EC 1.1.1.34) is the rate limiting step in the mevalonate pathway that produces isoprenoids and cholesterol. Inhibitors of HMG-CoA reductase are teratogenic in vivo and induce neural tube defects in rat embryo culture, effects which appear unrelated to cholesterol deficiency. This study is the first to localize HMG-CoA reductase mRNA by in situ hybridization (ISH). Expression of reductase mRNA was examined in post-implantation rat embryos, and for control purposes in rat liver and UT-1 cells, using a digoxigenin-11 (dig-11) labelled cRNA probe. Eighteen-day fetal liver showed heavy but patchy hybridization, and adult rat liver showed strong hybridization only on some periportal hepatocytes, which was absent in livers of fasted animals. UT-1 cells stimulated to overexpress HMG-CoA reductase mRNA were strongly positive with the same probe. Control hybridizations with sense strand RNA probe, or with cRNA probe on pre-RNased tissue were negative. Strong hybridization signal for HMG-CoA reductase mRNA was observed in all tissues of the post-implantation rat embryo, from egg cylinder to 30 somite stages (7 to 12 days). Heavy signal was noted in primitive ectoderm and neural tube. The wide embryonic and extraembryonic distribution and abundance of HMG-CoA reductase mRNA may reflect developmental requirements for products of the mevalonate pathway, e.g., isoprenoids for post-translational farnesylation of p21ras. 相似文献
103.
X Meng X Lu Z Li ED Green H Massa BJ Trask CA Morris MT Keating 《Canadian Metallurgical Quarterly》1998,103(5):590-599
Williams syndrome (WS) is a contiguous gene deletion disorder caused by haploinsufficiency of genes at 7q11.23. We have shown that hemizygosity of elastin is responsible for one feature of WS, supravalvular aortic stenosis (SVAS). We have also implicated LIM-kinase 1 hemizygosity as a contributing factor to impaired visual-spatial constructive cognition in WS. However, the common WS deletion region has not been completely characterized, and genes for additional features of WS, including mental retardation, infantile hypercalcemia, and unique personality profile, are yet to be discovered. Here, we present a physical map encompassing 1.5 Mb DNA that is commonly deleted in individuals with WS. Fluorescence in situ hybridization analysis of 200 WS individuals shows that WS individuals have the consistent deletion interval. In addition, we identify three novel genes from the common deletion region: WS-betaTRP, WS-bHLH, and BCL7B. WS-betaTRP has four putative beta-transducin (WD40) repeats, and WS-bHLH is a novel basic helix-loop-helix leucine zipper (bHLHZip) gene. BCL7B belongs to a novel family of highly conserved genes. We describe the expression profile and genomic structure for each of these genes. Hemizygous deletion of one or more of these genes may contribute to developmental defects in WS. 相似文献
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108.
Martia Shahsavan Mohammadrasool Morovatiyan J.Hunter Mack 《International Journal of Hydrogen Energy》2018,43(29):13575-13582
The thermodynamic efficiency of internal combustion engines is primarily dependent on the compression ratio and specific heat ratio of the working fluid. Due to a higher specific heat ratio, using a noble gas and oxygen instead of air can increase the thermal efficiency. The lack of nitrogen in the working fluid also eliminates NOx formation. In this study, the three-dimensional turbulent injection of hydrogen into a constant volume combustion chamber has been modeled and compared to mixtures of oxygen with nitrogen, argon, and xenon at different injection velocities. The results indicate that the hydrogen jet has a longer penetration length in nitrogen compared to argon and xenon. However, smaller penetration lengths lead to more complex jet shapes and larger cone angles. Combustion in a noble gas environment results in higher temperatures and OH radical concentrations, due in part to lower specific heats and the jet characteristics. Furthermore, mixedness is investigated using mean spatial variation and mean scalar dissipation. Hydrogen in argon shows a better mixing rate compared to nitrogen and xenon due to the higher diffusivity. The results indicate that reduction in mean spatial variation can lead to a shorter ignition delay. 相似文献
109.
综述了近年来稀土配合物杂化材料的制备和性能.按基质的不同,稀土配合物杂化材料可分为稀土配合物,无机杂化材料,稀土配合物,有机杂化材料以及稀土配合物,混合基质杂化材料。本文对以上3种杂化材料的优缺点进行了较为详细的分析,并提出一步法制备稀土配合物杂化材料,以简化合戍步骤,提高稀土配合物在基质分布的均匀性,因而该方法有望戍为制备稀土配合物杂化材料的一个重要发展方向。 相似文献
110.
应用电导率法研究了TritonX-100/正戊醇/环己烷体系中各组分及条件对微乳液最大增溶水量的影响。结果表明:当表面活性剂TritonX-100用量为3ml,助表面活性剂选正戊醇用量为1ml,环己烷为油相,温度为48℃,Ca(NO3)2溶液与(NH4)2HPO4溶液分别为0.24和0.14mol/L时,体系增溶水量最大,可得到较高产率的纳米羟基磷灰石。并且用XRD和TEM手段对产物进行了表征。 相似文献