An enamine controlling group for rhodium-catalyzed intermolecular hydroacylation

An enamine-controlled hydroacylation of alkynes using a rhodium(I)/dppe catalyst system is described. The reaction is highly selective, forming the linear enaminone products as single regioisomers in all examples. In situ hydrolysis of the enamine functionality generated α-substituted 1,3-diketone products, and Lewis-acid mediated intramolecular conjugate addition of the hydroacylation products gave substituted hexahydroquinolones.     

曲线加筋Kirchhoff-Mindlin板自由振动分析

相比传统加筋板,曲线加筋板能够更充分地发挥材料力学性能.在加筋板力学分析中,厚板通常采用Reissner-Mindlin理论,然而当板厚较薄时易出现剪切自锁,离散的Kirchhoff-Mindlin理论采用假设剪切应变场可避免该问题.针对曲线加筋Kirchhoff-Mindlin板自由振动分析,采用离散的Kirchhoff-Mindlin三角形单元和Timoshenko曲梁单元分别模拟板和加强筋,根据板的位移插值函数及筋板交界面的位移协调条件,建立基于板单元位移自由度的有限元方程.为了验证方法的有效性和准确性,采用直线加筋薄板、曲线加筋薄板和厚板3种模型进行算例研究,通过收敛性和精度分析来选择合理的有限元网格密度.直线加筋薄板前20阶固有频率均与文献结果吻合良好;曲线加筋板算例中,本文方法满足收敛条件的板单元数目为2469,Nastran模型板单元数目为6243;本文所得曲线加筋板固有频率与Nastran计算结果最大误差为3.4%.研究结果表明,本文方法无需筋板单元共节点,可使用较少的有限元网格数量,并能够保证计算精度;在离散Kirchhoff-Mindlin三角形板单元基础上构造Timoshenko梁单元可同时适用于曲线加筋薄板与厚板自由振动分析.     

Solid-state synthesis of graphite carbon-coated Li4Ti5O12 anode for lithium ion batteries

Graphites are widely used for their high electrical conductivity and good thermal and chemical stability. In this work, graphitic carbon-coated lithium titanium (Li₄Ti₅O₁₂/GC) was successfully synthesized by a simple one-step solid-state reaction process with the assistance of sucrose without elevating sintering temperature. The lattice fringe of 0.208 nm clearly seen from the high-resolution transmission electron microscopy (HRTEM) images was assigned to graphite (010). The average grain size of the as-prepared Li₄Ti₅O₁₂/GC was about 100–200 nm, 1 order smaller than that of pure Li₄Ti₅O₁₂ prepared similarly. The rate performance and cycle ability were significantly improved by the hybrid conducting network formed by graphitic carbon on the grains and amorphous carbon between them. The specific capacity retention rate was 66.7 % when discharged at a rate of 12C compared with the capacity obtained at 0.5C. After 300 cycles, the capacity retention was more than 90 % at a high rate of 15C.     

胺基化超高交联吸附树脂对苯酚和苯胺吸附行为的研究

在超高交联吸附树脂上负载不同胺基后,无论是在非水体系还是在水体系中,树脂对苯酚的吸附选择性大大增强.非水体系中,树脂对苯胺和苯酚的吸附是靠氢键作用,水体系中,树脂对苯酚的吸附是表面吸附和基团吸附综合作用的结果.动态吸附表明,树脂胺基化前(Rf18)树脂与季铵化后(Rs6 ) ,对苯胺和苯酚混合水溶液的动态吸附泄漏曲线差别较大.对Rf18树脂,苯酚首先在14 7BV(床体积)处泄漏,其泄漏液浓度上升很快,在2 12BV处达吸附饱和,苯胺在184BV处才开始泄漏,且其泄漏液浓度上升缓慢;在14 7～184BV之间可收集到苯酚溶液.对Rs6树脂,苯胺先泄漏(17BV处) ,其泄漏浓度很快趋于水平,在4 7BV处达吸附饱和;苯酚在4 4BV处开始泄漏,其泄漏曲线也上升很快,在79BV处趋于水平,在17～4 4BV之间可收集到苯胺水溶液.     

Disodium terephthalate/multiwall-carbon nanotube nanocomposite as advanced anode material for Li-ion batteries

Organic small molecule materials have attracted extensive attention due to their environmentally friendly, sustainability, and low cost which can be obtained from biomass and recyclable resources for Li/Na-ion batteries. However, the intrinsic poor electronic conductivities and the dissolution in organic liquid electrolyte lead to poor electrochemical performance, thus preventing them from practical application. To tackle these issues, herein, we take disodium terephthalate (Na₂TP) as an example and report an organic/multiwall-carbon nanotube nanocomposite via a simple spray drying methodology as an anode material for Li-ion battery. It delivers improved electrochemical performance compared to the pristine Na₂TP microspheres produced by the same spray drying method and the bulk microsized Na₂TP prepared by a conventional water-crystallization method. This is mainly due to the as-prepared nanocomposite can shorten the Li-ion diffusion distance, form highly conductive network and slow the dissolution rate. Our simple methodology could be of interest designing newly organic composites.     

有机电路及其基本元器件

半导体电路及其元器件是实现现代信息传递的重要组成部分,随着无机电路特别是硅基电路的研究发展进入瓶颈,有机电路及其基本元器件的研究对于电路及系统的未来发展意义更加重大。近十年来,有机电路及其基本元器件取得了飞速的发展,多种基本元件器性能已经达到可应用程度,特别是在显示领域,基于有机半导体制备的OLED显示电路已经成为新一代显示器的选择。同时,有机电路也因其所具有的低成本、可弯折、高透光等特性而具有了更多的发展空间。本综述从构成有机电路的各基本部件出发,以各部分器件在电路系统中的应用为线索,从系统信息采集、信息处理、信息存储和信息输出4个方面简述了各部分基础元件的发展情况,并以基于有机场效应晶体管的器件为基础,对器件的结构、电性能的优化以及所面临的问题进行了讨论。     

冲击波作用下碳水混合物发射光谱研究

 利用二级轻气炮和OMA-Ⅲ光多通道系统,分别研究金刚石与水、石墨与水两种碳水混合物在冲击波作用下的发射光谱。冲击压力高于16.41 GPa时,观测到350～750 nm波段内叠加在连续辐射背景上的发射谱;当冲击压力高于33.95 GPa时,C₂、CO、CO₂的谱线辐射明显,表明碳和水发生了化学反应。