离子交换树脂催化合成2-(1-环己烯基)环己酮

以环己酮为原料，利用双套管连续催化缩合反应及分离装置，在离子交换树脂催化下，制备2-(1-环己烯基)环己酮．考察了反应温度、反应时间、不同类型的离子交换树脂对2-(1-环己烯基)环己酮收率的影响．从而确定反应条件为：反应时间2．5h、反应温度85℃／2．0kPa，以HD-8型苯乙烯阳离子交换树脂为催化剂，在此条件下，2-(1-环己烯基)环己酮的收率达到85％以上．     

天然橡胶/丁苯橡胶基隔膜材料的制备与性能

采用相转换法制备出了以天然橡胶(NR)/丁苯橡胶(SBR)为基的多孔状聚合物锂离子电池隔膜材料,系统研究了成膜的工艺参数及机理.利用扫描电镜(SEM)和原子力显微镜(AFM)观察了该聚合物隔膜的微观结构,同时考察了该聚合物膜的吸液保液能力、热稳定性及电化学性能.结果表明,该聚合物膜呈多孔蜂窝状,具有较高的吸液能力,在电解液中浸泡5h后的吸液率达320%,此时该聚合物多孔隔膜的室温电导率也达到了3.93×10-4S/cm;并且保液能力良好,在50℃的空气中保持5h的质量损失仅为31%.同时该聚合物多孔膜具有较宽的电化学稳定窗口和较高的热分解温度,在4.8V和157℃以下能安全使用.与金属锂电极间的界面阻抗在存放10天或经过20次循环伏安扫描内迅速增加,而后趋于稳定,表现出了良好的界面稳定性,有效地抑制了电极与隔膜间的钝化膜(SEI)的进一步生长.     

用于核天体物理实验的活性靶时间投影室

发生在中子星壳层内的丰中子熔合反应对中子星演化以及X射线超级爆等现象均会产生影响。受限于放射性束流强度和反应机制的复杂性，实验数据极其缺乏，难以有效约束理论模型。基于活性靶技术的时间投影室(Time Projection Chamber，TPC)将工作气体作为反应靶，具备近4$\pi$立体角接受度和三维径迹重建能力，能够实现对反应事件的全记录，显著提高了探测效率，大幅降低了熔合反应截面测量对束流强度的要求。我们研制了240路信号读出的TPC，并使用放射性束流16N对探测器进行了测试，探索了该实验方法的可行性和有效性。为了得到更加精确的反应产物径迹，对反应事件做出更好的筛选，进一步发展了1 024路信号读出TPC，并开展了12C+12C库仑位垒附近熔合反应截面测量实验，初步实验结果与已有实验数据符合较好。     

A Convenient Method for Reductive Desulfonylation of β-Ketosulfones with Sm/HgCl2 System

The Sm/HgCl₂ system reduces β-ketosulfones to the corresponding ketones in moderate to good yield under mild conditions.     

多组分反应合成吡喃衍生物的研究进展

综述了近几年来利用多组分反应合成吡喃衍生物的研究进展,详细地介绍了不同底物参与的反应所需的条件,产率和机理研究,并对其发展方向加以展望.     

Can Flory-Stockmayer theory be applied to predict conventional free radical polymerization of multivinyl monomers? A study via Monte Carlo simulations

The conventional free radical polymerization (FRP) of multivinyl monomers (MVMs) inevitably leads to gelation even at low monomer conversion resulting in difficulties to control and monitor the reaction process. Flory and Stockmayer (F-S theory) studied it based on two fundamental assumptions: (1) independent and equivalent vinyl groups; (2) no intramolecular cyclization. However, until now its applicability to FRP of MVMs (especially regarding the extent of intramolecular cyclization) is still controversial. In this paper, Monte Carlo simulations are used to study FRP of divinyl monomers by two kinetic models: with/without cyclization models. The results of the simulations are compared with the calculated gel points based on F-S theory and the experimental data. It is found that the intramolecular cyclization has a negligible impact on the polymerization process and the gel point before gelation, which are in agreement with the prediction by F-S theory, but the effect becomes significant above the gel points.     

Preparation of carbon coated Fe3O4 nanoparticles and their application for solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples

The carbon coated Fe₃O₄ nanoparticles (Fe₃O₄/C) were synthesized by a simple hydrothermal reaction and applied as solid-phase extraction (SPE) sorbents to extract trace polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. The Fe₃O₄/C sorbents possess high adsorption capacity and extraction efficiency due to strong adsorption ability of carbon materials and large surface area of nanoparticles, and only 50 mg of sorbents are required to extract PAHs from 1000 mL water samples. The adsorption attains equilibrium rapidly and analytes are eluted with acetonitrile readily. Salinity and solution pH have no obvious effect on the recoveries of PAHs, which avoids fussy adjustment to water sample before extraction. Under optimized conditions, the detection limits of PAHs are in the range of 0.2–0.6 ng L⁻¹. The accuracy of the method was evaluated by the recoveries of spiked samples. Good recoveries (76–110%) with low relative standard deviations from 0.8% to 9.7% are achieved. This new SPE method provides several advantages, such as high extraction efficiency, high breakthrough volumes, convenient extraction procedure, and short analysis times. To our knowledge, this is the first time that Fe₃O₄/C nanoparticles are used for the pretreatment of environmental water samples.     

Influence of Ionic Strength on Electrochemical Responses of Myoglobin Loaded in Polysaccharide Layer‐by‐Layer Assembly Films

Two polysaccharides hydroxyethyl cellulose ethoxylate (HECE) and hyaluronic acid (HA) were assembled into {HECE/HA}_n layer‐by‐layer films on electrodes. The films were then immersed in myoglobin (Mb) solutions to load Mb into the films. The Mb‐loaded films showed a nearly reversible cyclic voltammetric (CV) peak pair at ?0.34 V vs. SCE in pH 7.0 buffers. The effect of ionic strength in Mb loading solutions and CV testing solutions on the CV response of the films was investigated. The direct electrochemistry of Mb loaded in the films could also be used to electrocatalyze the reduction of oxygen and H₂O₂ in solution.