糠醛液相原位加氢反应的热力学适配性分析

糠醛加氢脱氧可以转化为2-甲基呋喃等高值化学品。基于吉布斯自由能最小化原理,选取甲醇、乙醇为供氢剂,应用Aspen Plus软件对"醇-水-糠醛"液相原位加氢体系进行了热力学计算,以分析供氢反应与加氢反应热力学上的适配性。结果表明:制氢反应的适宜温度在500 K以上,而加氢反应更适合在低温下进行;甲醇作为供氢剂与糠醛液相原位加氢有好的适配性。分析反应条件对糠醛液相原位加氢平衡产物的影响发现,反应温度、压力及供氢剂用量都对产物分布有一定的影响,其中当原位供氢不足时易发生糠醛脱羰生成呋喃反应,供氢充足时糠醛加氢的主要产物为2-甲基呋喃和2-甲基四氢呋喃。     

甲醇水蒸气重整制氢铜基催化材料的研究进展

近年来催化甲醇水蒸气重整制氢已成为国内外催化领域研究的热点之一.与其它催化体系相比,铜基催化剂对甲醇制氢有优异的催化活性和低CO选择性,此工作系统总结了甲醇水蒸气重整制氢铜基催化剂的研究进展.按最新研究主要分为:传统铜基催化剂和新型催化剂,传统铜基催化剂又分为不同载体负载的铜基催化剂和改性铜基催化剂.分别介绍了各类催化...     

木素在过氧化氢漂白条件下的反应

综述了木素与H2O2有关反应的研究成果,介绍了木素在常规、高温高压和氨基氰活化等啦Q漂白条件下的变化,讨论了木素在不同反应条件下进行H2O2漂白的反应机理.     

氢氧直接合成过氧化氢贵金属催化剂研究进展

综述了近年来国内外在氢氧直接合成过氧化氢方面的研究进展,包括Pd催化剂的活性组分、Au催化剂、载体、反应介质的研究进展.重点探讨了Pd基催化剂活性态及其改性对氢氧直接合成过氧化氢活性的影响.指出非贵金属掺杂的负载型双金属催化剂及其改性、催化机理研究将是氢氧直接合成过氧化氢催化剂研究的发展方向.     

大豆蛋白纤维双氧水-尿素漂白工艺研究

探讨了有尿素存在下的大豆蛋白纤维双氧水漂白工艺,分析了双氧水、尿素用量、pH值、温度对处理效果的影响。结果表明,双氧水-尿素漂白工艺优于常规工艺。     

用双氧水／乙二醛对真丝绸低温染色

本文就双氧水/乙二醛氧化还原系统,对蚕丝织物低温染色进行了研究。讨论了影响染色的若干因素,并制定了可行的染色工艺,在染色机理方面也作了初步探讨。     

Determination of total nitrogen and cyanide nitrogen in cassava

Heating of intact cassava leaves causes liberation of hydrogen cyanide. This phenomenon appears to be caused by β-glucosidase-catalysed decomposition of the cyanogenic glycosides linamarin and lotaustralin. Because of these losses, many previously determined values for total nitrogen in cassava (and other cyanogenic plants) are probably in error as plant materials used for Kjeldahl determinations are often dried at 70–90°C. Liberation of cyanide from intact cassava leaves by heating at 80°C is more complete than liberation by the homogenisation methods commonly used. Homogenisation of cassava leaf tissues with liquid nitrogen or dry ice gives somewhat lower values, and these materials are often not readily available in areas where cassava is studied. The basis of a relatively simple procedure for the isolation of hydrogen cyanide from cassava leaves is suggested.     

维纶基牛奶蛋白纤维的漂白与染色研究

探讨双氧水对牛奶纤维针织物的漂白工艺,以织物白度、织物顶破强力为评价指标,优化了双氧水和还原剂漂白的工艺。在此基础上,进一步优化维纶基牛奶纤维双漂工艺,发现双氧水→二氧化硫脲漂白法效果最佳。通过分析活性染料、酸性染料、毛用活性染料、阳离子染料、分散染料等染料对维纶基牛奶纤维的染色,并与羊毛、丝绸和大豆纤维的染色性能作比较,初步探讨其染色性能。     

The methionine precursor dl-2-hydroxy-(4-methylthio)butanoic acid protects intestinal epithelial barrier function

dl-2-hydroxy-(4-methylthio)butanoic acid (HMTBA) is a source of dietary methionine (Met) that is widely used in poultry nutrition. We have previously shown that HMTBA is preferentially diverted to the transsulfuration pathway, which gives antioxidant metabolites such as taurine and glutathione. Therefore, here we hypothesize that this Met source can protect epithelial barrier function in an in vitro model of intestinal inflammation of Caco-2 cells. The results show that HMTBA prevents the increase in paracellular permeability induced by H₂O₂ or tumour necrosis factor-α. This effect can be attributed to the increased production of taurine and reduced glutathione. Similar results were obtained for dl-Met, although the protective role of the amino acid was less pronounced than that of the hydroxy analogue. In conclusion, the diversion to the transsulfuration pathway means that this Met precursor is of greater value than previously thought, due to its capacity to improve intestinal homeostasis and the quality of poultry products destined for human consumption.