Synthesis of Macrocyclic Arsinous Acid Estcrs

MacrocyclicarsinousacidestersareusuallypreparedbycondensationofdichloroalkylarsinesRAsCI,Iwithdidsinthepresenceoforganicalkali].ThemethoddescribedhereinvolvesthetransformationofintermediatefromItohis(dimethylamino)alkylarsineRAs(NMe,),2andthereactionof2withdidsindryTHFtoleadtotheformationoftitlecompounds.2canreactsmoothlywithdidsintheabsenceoforganicalkalitogeneratecorrespondingmacrocyclicarsinousacidesters4anddimethylaminewhichescapesfromthereactingsystemasagasinreflux.Althoughonemoreste…     

Accelerated hydrolysis of esters catalyzed by receptors, II. Degradation of RNA by polyvinylpyrrolidone

The nonenzymatic hydrolysis of RNA by polyvinylpyrrolidone (PVP) has been investigated. A bell-shaped kinetics was observed when the first order rate constant of the reaction was ploted as a function of PVP concentration, which means the kinetic feature of PVP as a degradative receptor distinct from those of degradative enzymes (e.g., ribonuclease).     

CaAl2B2O7：Eu的振动光谱和发光特性

采用高温固相反应法,合成了ＣａＡｌ２Ｂ２Ｏ７：Ｅｕ磷光体。测定了ＣａＡｌ２Ｂ２Ｏ７：Ｅｕ的振动光谱,结果表明ＢＯ３的振动吸收位于１４００－１６００ｃｍ＾－１区域内,ＡｌＯ６的吸收位于５１９ｃｍ＾－１。     

咪唑环番仿生新体系研究进展

仿生化学是当今化学的挑战性领域之一。咪唑环番是构筑仿生体系的优良基体,但迄今研究工作极少。本文简要评述了咪唑的选择性反应和咪唑衍生物的选择性合成、新型咪唑环番和咪唑鎓环番的设计合成及仿生功能研究的一些新进展。     

锂离子电池锂锰氧化物高压嵌锂材料的结构和电化学性能研究

利 用 Ｘ Ｒ Ｄ、 Ｉ Ｃ Ｐ、 Ｔ Ｇ Ａ 、 Ｄ Ｔ Ａ 及 恒 流 充 放 电 等 方 法 研 究 分 析 了 一 种 特 殊 天 然 结 构 Ｍｎ Ｏ２（ Ｎ Ｍ Ｄ） 材料的结 构、组成 以及电 化学嵌锂 特性． Ｘ Ｒ Ｄ 分析 表明,该样 品材料 是由钠水 锰矿以及水羟 锰矿复 合结构组 成的 Ｍｎ Ｏ２ 纳米 纤 维． 充放 电 循环 结果 显 示,其 前 期循 环容 量 可高 达 １５０ｍ Ａｈ／ ｇ 左 右,但性 能尚不够 稳定． 本文采 用一种 水热法高 压嵌锂处 理,可将 Ｎ Ｍ Ｄ 样品 转变为 具有３ ×３ 大隧道结 构的钡 镁锰矿（ Ｔｏｄｏｒｏｋｉｔｅ） 型锂 锰氧 化 物,既 增 强了 Ｌｉ ＋ 嵌 入 隧道 或 层间 结 构 的循环稳定 性． 并 显著提 高锂锰氧 化物电 极材料性 能的 稳定 性,以 充放 电电 流密 度 为０ ．８ ｍ Ａ／ｃ ｍ ２ ,经过１８０ 次 循环后 其比容量 仍具有 １１０ ｍ Ａｈ／ ｇ ． 该类 大隧道结 构锂锰 氧化物可 作为一 种３ Ｖ 的锂离子电极 材料．     

尼龙1010／6及尼龙1010／66动态力学分析

通过动态力学参数温度谱,研究了尼龙１０１０／６、尼龙１０１０／６６两个共聚物系列的动态力学参数与组成的关系。研究表明尼龙１０１０／６、尼龙１０１０／６６在测试温度范围内出现三个明显的松驰转变：α、β、γ,其中各共聚物的β、γ松驰温度相差不大,而α松驰温度随组成改变有明显改变。一般均聚物的α松驰温度较高,共聚物的α松驰温度均低于均聚物,二个系列以尼龙１０１０／６（２９．８／７０．２）、尼龙１０１０／     

Ionic strength/temperature-induced gelation of aqueous poly(N-isopropylacrylamide-co-vinylimidazole) solution

A high molecular weight copolymer of N-isopropylacrylamide (NiPAAm) and vinyl imidazole (VI) was synthesized and its phase transition behavior in aqueous solutions (5 wt%) by simultaneous changes of ionic strength and temperature was investigated. At low ionic strengths, the copolymer solution showed two phases (clear and opaque solutions), which were freely mobile, as increasing temperatures up to 65°C due to repulsion interaction of positive charges developed by basic imidazole group on the polymer aggregates. However, at the physiological condition (I=0.15, T=37°C), four distinctive phases (clear solution, opaque solution, gel and shrunken gel) were observed because of charge shielding effect by added salts. The gel state was stable and maintained from 32°C to 55°C. In particular, the phase transition from opaque solution to gel rapidly occurred by the change in ionic strength (from ∼ 0 to 0.15) at 37°C. This characteristic can be utilized as a liquid embolic agent.     

壳聚糖及其疏水衍生物自缔合行为

过去几十年里,有关疏水改性聚电解质的理论和应用研究取得了长足的进展,通常认为其不同寻常的流变及溶解特性是由疏水基团的分子间或分子内相互作用产生的.本文综述了近年来有关壳聚糖及脱氧胆酸、烷基化和棕榈酰改性壳聚糖衍生物自缔合性质的研究进展,并简要介绍它们在药物释放和转基因领域的应用研究.     

A New Strategy for the Synthesis of Polytrithiocarbonates Using a Polymeric Support System

A new polymerization strategy, consisting of nucleophilic substitution reaction between CS₃^2‐, immobilized on a polymeric support, and dimethyl α,α′‐dibromoalkylanedioate in solution, leads to the formation of polytrithiocarbonates. When n = 0, 1 in CH₃OOCCHBr(CH₂)_nCHBrCOOCH₃ (α,α′‐dibromoalkylanedioate), only five‐ or six‐membered cyclic trithiocarbonates were obtained; n ≥ 2 resulted in the formation of polytrithiocarbonates.     

染料在青霉菌上的解吸特性研究

比较了有机溶剂的加入及温度变化对染料高效吸附青霉菌(BX1)解吸染料效果的影响,并对解吸过程的动力学进行了研究.结果表明,染料的解吸效果与有机溶剂的极性,以及溶剂的官能团有关,丙酮和甲醇解吸效果最好.解吸过程与吸附过程类似,可分为快速解吸和缓慢解吸两个阶段,整个过程可用二级动力学方程较好的拟合,其表观活化能约为10.64kJ/mol.△H°和△G°的计算表明,在甲醇作用下RB19染料的解吸为吸热和自发的过程.