A Convenient Synthesis Of 1-Acyl Indolizines by 1,3-Dipolar Cycloaddition Reactions of Pyridinium Ylides and α,β-Unsaturated Aldehydes or Ketones in the Presence of Tetrakis-Pyridine Cobalt Dichromate

In the presence of tetrakispyridine cobalt dichromate (CoPy₄(HCrO₄)₂), pyridinium ylides and α,β-unsaturated aldehydes or ketones undergo 1,3-dipolar cycloaddition reactions followed by in situ aromatization to give 1-acyl substituted indolizines in moderate to good yields.     

傍轴黎曼几何光学应用——光束自聚焦

利用光流体模型 ,计算模拟了激光束的自聚焦传输特性 ,得到与实验相一致的结果。     

一种低成本主边控制AC-DC充电控制器

设计了一种主边控制、工作于不连续模式的反激离线AC-DC锂离子电池充电控制器.采用新颖的恒流恒压控制方式保证充电精度,无光耦的应用拓扑能有效降低成本.基于0.5μm BiCMOS工艺模型,进行HSpice仿真验证.结果表明,恒流精度在±5%以内,充电终止电压精度在±1%以内.     

A Cost‐effective Nafion Composite Membrane as an Effective Vanadium‐Ion Barrier for Vanadium Redox Flow Batteries

Ion exchange membranes play a key role in all vanadium redox flow batteries (VRFBs). The mostly available commercial membrane for VRFBs is Nafion. However, its disadvantages, such as high cost and severe vanadium‐ion permeation, become obstacles for large‐scale energy storage. It is thus crucial to develop an efficient membrane with low permeability of vanadium ions and low cost to promote commercial applications of VRFBs. In this study, graphene oxide (GO) has been employed as an additive to the Nafion 212 matrix and a composite membrane named rN212/GO obtained. The thickness of rN212/GO has been reduced to only 41 μm (compared with 50 μm Nafion 212), which indicates directly lower cost. Meanwhile, rN212/GO shows lower permeability of vanadium ions and area‐specific resistance compared to the Nafion 212 membrane due to the abundant oxygen‐containing functional groups of GO additives. The VRFB cells with the rN212/GO membrane show higher Coulombic efficiencies and lower capacity decay than those of VRFB cells with the Nafion 212 membrane. Therefore, the cost‐effective rN212/GO composite membrane is a promising alternative to suppress migration of vanadium ions across the membrane to set up VRFB cells with better performances.     

Electrochemical performance of CeO<Subscript>2</Subscript> nanoparticle-decorated graphene oxide as an electrode material for supercapacitor

Cerium oxide nanoparticles and cerium oxide nanoparticle-decorated graphene oxide (GO) are synthesized via a facile chemical coprecipitation method in the presence of hexadecyltrimethylammonium bromide (CTAB). Nanostructure studies and electrochemical performances of the as-prepared samples were systematically investigated. The crystalline structure and morphology of the nanocomposites were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), Raman spectrum, and X-ray photoelectron spectroscopy (XPS). Electrochemical properties of the CeO₂ electrode, the GO electrode, and the nanocomposites electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The CeO₂ nanoparticle-decorated GO (at the mole ratio of CeO₂/GO = 1:4) electrode exhibited excellent supercapacitive behavior with a high specific capacitance of 382.94 F/g at the current density of 3.0 A/g. These superior electrochemical features demonstrate that the CeO₂ nanoparticle-decorated GO is a promising material for next-generation supercapacitor systems.     

整形激光脉冲与激光探针同步技术

实现了应用于神光Ⅱ装置中的高精度整形激光脉冲与激光探针同步方案。在该方案中,激光探针经硅光导开关进行光电转换之后作为激光脉冲整形单元的触发信号,使激光脉冲整形单元,输出与激光探针同步的整形激光脉冲。为了降低由于触发信号不稳定引起的时间晃动,在光电转换之前放大激光探针,以调整激光脉冲整形单元触发信号的幅度。在神光Ⅱ装置中实现了整形激光脉冲与激光探针小于4.5 ps(均方根)的时间同步精度。     

印制电路板的电镀铜技艺

介绍了酸性光亮镀铜在PCB制造中的应用,电镀铜溶液的一些基本常识,以及镀液的维护、保养情况,同时分析了一些常见故障及其成因和解决方法。     

含砷的铝标准物质的制备和定值

本文叙述了含砷铝标准物质的制备过程和定值结果。采用了间接加入法，以异基体的Cu-As中间合金形态把As加入并均匀分布在铝液中。用制备出的标准物质制作校准曲线，进行光谱分析，其结果与仲裁结果相符。本标准物质与俄罗斯的同类标准物质比对实验表明：本标准物质的主要特性指标达到或超过俄罗斯的水平。本标准物质制备成功，填补了国内无含As铝标准物质的空白，本标准物质可替代同类进口标准物质。     

Photonic crystal waveguide sampled gratings

Photonic crystal waveguide sampled gratings (PCWSG) are proposed to realize multi-channel optical filter in a photonic crystal (PC) waveguide. The reflection characteristics of the filter are analyzed by using the coupled-mode theory (CMT) together with transfer-matrix method (TMM). It is shown that the reflection spectrum of the filter exhibits a group of reflection peaks, which are distributed with equal frequency spacing within the photonic crystal bandgap (PBG). The theoretically calculated results are numerically verified by using two-dimensional (2D) finite-difference time-domain (FDTD) method.