Copper‐catalyzed one‐pot synthesis of propargylamines via C?H activation in PEG

An efficient and convenient three‐component A³ coupling reaction of aldehyde, amine and alkyne via C? H activation with CuI alone as the catalyst in PEG is developed, providing a wide range of propargylamines with yields ranging from moderate to excellent. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Simple synthesis of zwitterionic diblock copolymers for the application on metal nanoparticles preparation

AB diblock copolymers of poly(2-(dimethylamino)ethyl metharylate-block-potassiurn acrylate) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure of the block polymer was determined by the nuclear magnetic resonance (NMR) spectroscopy and the gel permeation chromatography. Moreover, it has also been shown that the diblock copolymers exhibit aggregate as function of the pH according to the result of ¹H-NMR spectroscopy, FT-IR absorption spectra, UV-vis transmittance spectroscopy, transmission electron microscopy and ultrasonic particle size analyzer. The result was attributed that such AB diblock copolymers were tailored to undergo pH-induced self-assembly. Furthermore, the aggregate can be as template of metal nanoparticles preparation, and the sizes of the aggregate, in turn, strongly control nanoparticle sizes.     

Perturbation of systems of linear algebraic equations ∗

A classical perturbation result for nonsingular systems of linear algebraic equations is extended to general consistent systems under any norm. An optimal perturbation result is also obtained for general linear least squares problems under a Euclidean norm.     

Copper‐catalyzed Clauson–Kass pyrroles synthesis in aqueous media

An efficient and convenient copper‐catalyzed Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with amines in aqueous media has been developed, providing a wide range of N‐substituted pyrroles in good yields. It is noteworthy that the Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with p‐phenylenediamine or m‐phenylenediamine proceeds smoothly to afford the corresponding monopyrroles and bispyrroles with high selectivity in impressive yields. A plausible mechanism for the formation of N‐substituted pyrroles has been proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Validity of Inorganic Nanosheets as an Efficient Planar Substituent To Enhance the Enantioselectivity of Transition‐Metal‐Catalyzed Asymmetric Synthesis

Effectively enhancing the enantioselectivity is a persistent challenge in heterogeneous asymmetric catalysis. Here, the validity of a layered double hydroxides (LDH) nanosheet as an efficient planar substituent to enhance the enantioselectivity has been investigated theoretically; first in vanadium‐catalyzed asymmetric epoxidation of allylic alcohols, and then in zinc‐catalyzed direct asymmetric aldol addition. The computational predication is further confirmed experimentally in zinc‐catalyzed direct asymmetric aldol addition by controlling the location of catalytic sites.     

光泽精与钨（Ⅲ）的流动注射－胶束增敏化学发光反应

采用了Jones柱在线还原钨（Ⅵ）为钨（Ⅲ），详细研究了钨（Ⅲ）与光泽精的化学发光反应，加入乳化剂OP能明显提高发光的信噪比，基于此建立了痕量钨的流动注射化学发光分析法。该法线性范围为1×10－6～1×10－2 g·L－1, 检出限为5×10－7 g·L－1 , 相对标准偏差为2.0％（5×10－5 g·L－1, n=11）。文中还探讨了反应机理。     

Mechanochemical synthesis of Na-β/β″-Al2O3

Na-β/β″-alumina powders were synthesized by a mechanochemical processing. The influences of mechanical activation in the phase composition and microstructure of the final powders were investigated. Fine Na-β/β″-alumina powders were obtained at a lower temperature than that of a conventional solid-state reaction processing. The mechanism of the mechanical activation was studied. It was found that mechanical activation greatly affected the calcining process and phase composition of the precursory powders.     

316L不锈钢在Saline溶液中的微动磨蚀行为研究

采用球－平面接触微动磨损试验设备考察了轧制固溶３１６Ｌ不锈钢在Ｓａｌｉｎｅ溶液中的微动磨蚀行为。研究表明,３１６Ｌ不锈钢的微动过程存在显著的阶段性;微动初期为磨合期,第一稳定阶段摩擦副处于高摩擦应力状态,伴随着不锈钢表面缝隙腐蚀与弹塑性损伤的积累;第二过渡阶段和第二稳定阶段不锈钢表面呈微断裂剥层特征,腐蚀引起的微断裂不可忽视,不锈钢微动损伤表面形貌同微动损伤速率之间存在对应关系。     

A Phenolic Glucoside from Alangium plantanifolium

Alangium, the sole genus in the family Alangiaceae, has a variety of about 20 species distributed in the tropical and subtropical area of the Eastern Hemisphere, and 13 species are known to occur in the south of China1. A. plantanifolium and A. chinense are used in chinese traditional medicine for the treatment of rheumatalgia, paralysis, cardianeuria, and wound2. Pharmacological studies of the extracts of these two species showed muscular relaxing activity, and anabasine was considered as t…     

微尺度圆管内气体流量的实验测量

以氮气和氦气为工作介质,研究了微尺度(φ=17.6μm,17.9μm)圆管内压力驱动的气体流动,测量了在不同进出口压力下的流量,并与计算值进行了比较.结果表明,即使对于极低Mach数(M=0.003～0.03)流动,其可压缩性仍十分明显,它来源于微尺度效应.在本文的实验参数下,Kundsen数范围为3×10-3～7×10-3,表面滑移不明显,稀薄气体效应可以忽略.