绿色催化合成己酸戊酯

研究了由正戊醇与己酸用复合固体酸催化剂绿色催化合成己酸戊酯。其最佳酯化反应条件为:正戊醇/己酸物质的量之比为1.7/1.0,反应25min,催化剂用0.5g,催化剂可重复利用,且活性高、无腐蚀性、酯化产品收率99%。

水热改性SO_4^(2-)/Al_2O_3/ZrO_2的制备及其对正丁烷异构化反应的催化性能

通过控制Zr(OH)4在母液中的回流时间,制备水热改性的Zr(OH)4。用X射线衍射、热重、氮气吸附等测试技术对Zr(OH)4和催化剂的理化性质进行分析,并通过正丁烷异构化反应考察了不同水热处理对催化剂活性的影响。结果表明,水热处理能够提高Zr(OH)4热稳定性及其在焙烧过程中的结晶温度和晶相转变温度。但长时间100℃下的水热处理,消耗了前躯体Zr(OH)4中部分羟基,影响了硫酸根与载体表面的稳定性结合继而影响到催化剂的催化性能。实验结果表明,随着水热时间的增加,样品的热稳定性,比表面积不断增大,但硫含量并不是单调递增。经96h水热处理制得的催化剂含硫质量分数低于1.1%,异构化反应中的转化率小于20%。而经水热回流处理24h制备的催化剂样品硫质量分数为1.45%,在正丁烷异构化反应中显示出优异的催化性能,250℃下的稳态转化率大于46%,接近该条件的平衡转化率。

合成异丙苯生产现状及技术进展

介绍了传统的异丙苯生产技术,综述了国内外合成异丙苯的生产现状及技术进展。针对国内合成异丙苯的研究现状,提出了今后重点是合成异丙苯的催化剂和反应工艺研究和开发。

The vanadium isotopic composition of L ordinary chondrites

Stable isotopic data of meteorites are critical for understanding the evolution of terrestrial planets. In this study, we report high-precision vanadium （V） isotopic compositions of 11 unequilibrated and equilibrated L chondrites. Our samples show an average δ^51v of -1.25‰ ±0.38‰ （2SD, n = 11）, which is ,- 0.5‰ lighter than that of the bulk silicate Earth constrained by mantle peridotites. Isotopic fractionation in type 3 ordinary chondrites vary from - 1.76‰ to - 1.29‰, whereas the δ^51V of equilibrated chondrites vary from - 1.37‰ to -1.08‰. 551V of L chondrites do not correlate with thermal metamorphism, shock stage, or weathering degree. Future studies are required to explore the reason for V isotope variation in the solar system.

Boosting chiral carboxylic acid hydrogenation by tuning metal-MO_(x)-support interaction in Pt-ReO_(x)/TiO_(2) catalysts

Engineering the surface microenvironment by tuning the binary interactions between a supported metal with a secondary metal oxide(MO_(x))or support has been a common method for improving the catalytic performance of supported metal catalysts.However,few studies have investigated the ternary interactions among the metal,MO_(x),and support.Here,we report for the first time the formation of metal-MO_(x)-support interaction(MMSI)in reducible TiO_(2)-supported PtReO_(x) catalysts,affording 87% yield and 100% ee in the tandem hydrogenation of an aqueous chiral cyclohexane-1,2-dicarboxylic acid into the corresponding diol;the catalytic activity is eight times higher than that obtained with non-reducible support counterparts in the same reaction via traditional batch synthesis with multiple steps and unfriendly reagents.Detailed experimental and computational studies suggest that the TiO_(2) crystalline phase-dependent density of the oxygen vacancies induces different Pt-ReO_(x)-TiO_(2) interactions,which dominate the electron transfer therein and tune the adsorption strength of the carbonyl moiety of the substrate/intermediate,thus promoting the hydrogenation activity and selectivity.In addition,the strong MMSI endows the optimal rutile TiO_(2) supported PtReO_(x) catalyst with an outstanding lifetime of 400 h in a fixed-bed reactor under acidic aqueous conditions and ensures efficient applications in the selective hydrogenation of aliphatic dicarboxylic acids and functional carboxylic acids.This work provides a promising strategy for the development of efficient and stable supported catalysts for the selective hydrogenation of diverse C-O and C=O bonds.

The Triazole and Thiophene Containing New Heterocyclic Systems

The aim of the current work is to create new heterocyclic tetracyclic condensed systems which combine benzothiofen and benzimidazoleinto one molecule. The haisic products are 1,2-, 2,3- and 3,4- diamines of dibenzothiophenes. Orto-diamines react with hydrochloric acid and sodium nitrite and obtain three new isomeric heterocyclic systems： 3H-benzothieno[3,2-e]benzotriazole, 3H-benzothieno[2,3-f]benzotriazole and 1H-benzothieno[3,2-g]benzotriazole with the anticipated biological activity. Their spectral characteristics are studied.

Effects of moxibustion on miRNA-133b,Pitx3/TH,and neurotransmitters in the midbrain of rats with diarrhea-predominant irritable bowel syndrome

Objective:To investigate the mechanism of moxibustion in the treatment of diarrhea-predominant irritable bowel syndrome(IBS-D),by observing the effects of moxibustion at Tianshu(ST25)and Shangjuxu(ST37)on microRNA-133b(miRNA-133b),pituitary homeobox family factor 3(Pitx3)/tyrosine hydroxylase(TH),and neurotransmitters in the brain tissue of IBS-D rats.Methods:Healthy Sprague-Dawley rats were randomly divided into a normal group,a model group,a moxibustion group,and a Western medicine group,with 12 rats in each group.Except for the normal group,the IBS-D rat model was established by mother-offspring separation and acetic acid enema combined with restraint stress stimulation in all the other groups.No intervention was performed in the normal and model groups.Mild moxibustion was applied to both Tianshu(ST25)and Shangjuxu(ST37)in the moxibustion group.Rifaximin was given by gavage in the Western medicine group.The physical status of rats in each group was observed at different periods.After the intervention,hematoxylineosin staining was performed to observe the histopathological morphology of rat colon;enzyme-linked immunosorbent assay was used to measure the levels of dopamine(DA),noradrenaline(NE),and 5-hydroxytryptamine(5-HT)in plasma,colon,and midbrain tissue of rats;the relative expression levels of miRNA-133b,Pitx3 mRNA,and TH mRNA in the midbrain tissue were measured by real-time fluorescence quantitative polymerase chain reaction,and the relative expression levels of Pitx3 and TH proteins in the midbrain tissue were measured by Western blotting and immunofluorescence.Results:The body weights of rats among groups and at different time points were statistically different(P<0.01).The body weight of the normal group was higher than that of the other groups over time(P<0.01).After modeling,the minimum volume threshold of abdominal withdrawal reflex(AWR)was significantly lower(P<0.01)and the loose stool rate was significantly higher(P<0.01)in the model,moxibustion,and Western medicine groups compared with the normal group;the miRNA-133b expression in the midbrain tissue was significantly lower(P<0.01),the expression levels of Pitx3 and TH in the midbrain tissue were significantly higher(P<0.01),and the levels of DA,NE,and 5-HT in plasma,colon and midbrain tissue were significantly higher(P<0.01).After the intervention,the minimum volume threshold of AWR was significantly higher(P<0.01),the loose stool rate was significantly lower(P<0.01),the miRNA-133b expression was significantly increased(P<0.01 or P<0.05)and the expression levels of Pitx3 and TH were significantly decreased(P<0.01)in the midbrain tissue,the levels of DA,NE,and 5-HT in plasma,colon,and midbrain tissue were significantly reduced(P<0.01)in the moxibustion and Western medicine groups compared with the model group;the levels of 5-HT in the colon and midbrain tissue of the moxibustion group were significantly lower than those in the Western medicine group(P<0.05),and there was no statistical difference compared with the remaining groups(P>0.05).Linear correlation analysis showed that miRNA-133b was negatively correlated with Pitx3(r<0,P<0.01);Pitx3 with TH,TH with DA,and NE with 5-HT were positively correlated(r>0,P<0.01).Conclusion:Moxibustion at Tianshu(ST25)and Shangjuxu(ST37)improves diarrhea symptoms and visceral hypersensitivity in IBS-D rats.The mechanism may be related to up-regulating miRNA-133b,inhibiting Pitx3/TH,and reducing neurotransmitter expression levels in the midbrain tissue.