A novel cyclopentene derivative and a polyhydroxylated steroid from a South China Sea gorgonian Menella sp

A chemical investigation on a South China Sea gorgonian, Menella sp. resulted in the isolation and elucidation of menellin A (1), a highly oxygenated racemate with C(8) skeleton, and a polyhydroxylated steroid, menellsteroid C (2), along with eight known compounds (3-10). The structures of the new compounds were elucidated by means of MS, 1D and 2D NMR spectra, and the relative stereochemistry of 1 was determined by X-ray single-crystal diffraction analysis. In addition, compound 7 was isolated as a new natural product. Compounds 1-3 and 7 were selected to test the anti-inflammatory inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. 1 and 3 exhibited modest inhibitory effects with IC(50) of 71.3, 33.9 μM, respectively, compared to the positive control aminoguanidine (IC(50) 25.0 μM).     

In-gel protein N- and C-termini identification and its application for transgenic protein characterization

A new method for the determination of N- and C-termini of a protein isolated in a polyacrylamide gel is introduced. In-gel partial protein hydrolysis by hydrochloric acid is used to generate N- and C-terminal peptides for identification. This new method is complementary to existing techniques. The application of the in-gel protein termini identification technique to the characterization of the transgenic protein diacylglycerol acyltransferase (UrDGAT2A) purified from soybean seeds is also reported here. Both N- and C-termini of UrDGAT2A were successfully identified and the N-terminus was found to be blocked by acetylation. The analysis results of UrDGAT2A and two commercial proteins (bovine serum albumin (BSA) and alcohol dehydrogenase) are used to demonstrate the effectiveness of the method in identifying actual N- and C-termini, terminal truncation and blocking.     

GO增强UHMWPE在透明质酸钠润滑介质下的摩擦学性能研究

采用UMT-3MT往复式滑动摩擦磨损试验机,研究在透明质酸钠(SHA)润滑介质下,氧化石墨烯(GO)对基体材料超高分子量聚乙烯(UHMWPE)摩擦学性能的影响.利用高分辨扫描电子显微镜(HR-SEM)和MicroXAM非接触式3D表面轮廓仪观察试样表面磨痕形貌并计算其磨损率.结果表明:在SHA润滑介质下,无机填料GO的添加显著降低UHMWPE基复合材料的磨损率,但是,GO的添加对复合材料稳态摩擦系数和残留在SHA润滑介质中的磨粒特征无明显影响.无机填料GO的添加增强了UHMWPE在SHA润滑介质下的耐磨性能.     

氰基衍生化制备胺的研究进展

胺是有机分子中最常见且重要的结构之一,广泛存在于天然产物分子、药物、染料、塑料等的分子结构中,开发合成胺的有效方法在化学工业中具有很高的需求但仍充满挑战。在诸多已知有机胺的合成方法中,以氰基为前体还原衍生化制备胺被认为是一条原子经济且绿色可行的方案。然而,氰基中存在稳定的碳氮三重键,还原过程涉及较多中间体,而部分中间体活性比氰基更高,因此反应受还原剂、催化剂、反应条件的影响很大,由氰基选择性制备目标胺结构仍充满挑战。本文从氰基的基本电子结构与反应活性出发,综述了近年来以氰基为原料的官能团胺基化反应,对部分重要反应的催化剂和反应机理做了简要讨论,为设计氰基制胺催化剂和应用工艺提供了新的视角。     

Simultaneous direct analysis of benzimidazole fungicides and relevant metabolites in agricultural products based on multifunction dispersive solid-phase extraction and liquid chromatography–mass spectrometry

A fast and flexible multi-residue procedure for effective extraction of benzimidazole fungicides and the related transformation products in various raw agricultural commodities is developed for direct and simultaneous analysis by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The new sample preparation method, introduced to allow direct extraction of the labile fungicides as the intact forms in complex matrices, is achieved using a conservative homogenizing extraction and multifunction adsorption cleanup (CHEMAC), which basically involves salting-out partitioning/extraction with acetate-buffered acetonitrile at low-temperature and sequential rapid solid-phase dispersive cleanup with a ternary sorbent mixture. The CHEMAC procedure was optimized and further modified by incorporating several pretreatment variables influencing sample stability and process efficiency, such as pH, temperature, salt and sorbent utilized. By using CHEMAC, a noteworthy improvement in extraction recoveries was obtained for the problematic fungicides, while no significant differential matrix effects were detected on the LC–MS/MS analysis in all 9 matrices. The in-source fragmentation of benomyl occurred but caused no cross-talk interference in multi-component analysis. Thus the CHEMAC-based LC–MS/MS strategy can serve as an attractive approach to satisfactory overall process efficiencies (70–92%) with acceptable repeatability (relative standard deviations below 16%) for all the analyte–matrix combinations. Mean accuracies were obtained within the range of 70–110% at fortified levels of 1–500 ng/g, with intra-day and inter-day variations less than 15 and 20%, respectively. The successful practical application of the proposed method to real samples has also been demonstrated.     

SO42−/ZrO2 上异丁烷重构化反应机理的原位核磁共振研究

 采用原位魔角旋转固体核磁共振技术研究了 2-13C-异丁烷在 SO42−/ZrO2 上的重构化反应机理, 考察了反应温度和 H2 气氛对反应的影响. 结果表明, 反应初期, 异丁烷在 SO42−/ZrO2 上的重构化反应以单分子机理为主, 之后向双分子机理转变; 反应温度的升高有利于单分子机理向双分子机理的转变; H2 的存在抑制了异丁烷的重构化反应, 特别对其双分子机理的反应有较强的抑制作用.     

氮化硼载体对 Ru-Ba/BN 氨合成催化剂性能的影响

 研究了不同方法合成的氮化硼 (BN) 的性质及其负载的 Ru-Ba 催化剂对氨合成的催化性能. 采用 X 射线粉末衍射、N2 吸附-脱附、扫描电镜和傅里叶变换红外光谱等手段对所合成的 BN 样品进行了表征. 结果表明, 采用程序升温氮化和程序升温还原法均能在低于 900 oC 的条件下合成出较纯的六方相 BN, 其比表面积分别达到 103 和 138 m2/g. 其中前者负载 Ru-Ba 的催化剂活性更高, 在 475 oC, 10 MPa 和 10 000 h–1 的条件下出口氨浓度达 7.3%, 且在 550 oC 热处理 30 h 后, 活性基本保持不变.     

介孔氧化铝负载钒催化剂上丙烷氧化脱氢制丙烯

 采用浸渍法制备了介孔氧化铝 (m-Al2O3) 负载钒催化剂 (V/m-Al2O3), 并考察了其催化丙烷氧化脱氢制丙烯反应活性. 通过 N2 吸附-脱附、透射电镜、X 射线粉末衍射、紫外-可见漫反射光谱、氢-程序升温还原和氨-程序升温脱附对催化剂进行了表征. 结果表明, 介孔氧化铝具有大比表面积、窄孔径分布和两维六方相结构, 在其上负载适量的 V 可实现 V 活性物种的高分散及催化剂的弱酸性, 从而有利于提高丙烷转化率和丙烯选择性. 与共合成法制备的含 V 介孔氧化铝 V/m-Al2O3(C) 和浸渍法制备的 V/?-Al2O3 相比, V/m-Al2O3 表现出更高的催化活性. 这与载体较弱的酸性和较大的比表面积以及 V 物种的高分散有关.