Ethylenediamine promoted the hydrogenative coupling of nitroarenes over Ni/C catalyst

In this work, we found that ethylenediamine can enrich the electron state of Ni and make the azobenzene easily desorb from the surface of the catalyst, which effectively inhibits the further hydrogenation to aniline and greatly improves the selectivity of azobenzene. When the ratio of Ni and ethylenediamine is 1:10, the yield of the azobenzene can reach 95.5%.     

BEPCⅡ超导腔垂直测试杜瓦的漏热分析与实验研究

北京正负电子对撞机重大改造工程(简称BEPCⅡ)采用了超导射频技术,超导腔设备在与低温恒温器总装之前,必须进行液氦温度下垂直位置的性能测试.测试杜瓦的绝热性能对超导腔的垂直测试性能产生直接影响,准确测算测试杜瓦的漏热量对垂直测试方案的制定、减少液氦消耗量具有重要的指导意义.对测试杜瓦的主要漏热部分进行了计算,同时以液氮...     

Preparation and characterization of biosurfactant based on hydrophobically modified alginate

Hydrophobic modified alginate (HM-alginate) was synthesized using a low-energy, environment-friendly process in aqueous solution, with sodium alginate and dodecyl glycidyl ether as starting materials. The HM-alginate was characterized using ¹H NMR, and the reaction efficiency was about 40%. The HM-alginate aggregated in solution; the critical micelle concentration (CMC) was determined using surface tension and dynamic light scattering methods. We observed reasonable agreement between the CMC values obtained by the different techniques, and the CMC was 4.0 × 10^?4 g/mL. The zeta-potential of the HM-alginate in aqueous solution was about ?82 mV, which is higher than ?51 mV of the sodium alginate. Rheology measurements showed that the HM-alginate solution exhibits a Newtonian behavior at all shear rates, whereas the apparent viscosity is very low. The solubility of the liposoluble substance Sudan IV increased significantly with HM-alginate concentration. This result is promising for potential applications of HM-alginate as an ecology-safe material to encapsulate lipophilic substances.     

快速高精度电子元件温度特性测量仪的研制

大多数电子元器件的性能受到工作温度的影响,其温度特性对设备稳定性和精确度的影响不容忽视。以半导体致冷器(TEC)为核心,ATMega128A单片机为控制芯片,采用PT100、高精度恒流源和AD7731数模转换器(ADC)组成温度测量模块,运用改进的PID控制算法,以脉冲宽度调制(PWM)方式驱动优化的H桥精确控制加热和制冷功率,结合优化设计的变温腔体,制作了快速、高精度电子元件温度特性测量仪。在-10_oC~80_oC之间快速、稳定控制待测元件的温度,控温精度达到±0.2_oC。通过计算机控制数字万用表等测量设备,测量了电阻、电容和电感的温度特性曲线。该测量仪还可以用于IC、三极管和LED等元器件的温度特性曲线研究。在实验研究、工业生产和电子实验教学中均具备很高的实用价值。     

免光学间隔层的高效聚合物太阳能电池

使用相对聚(3乙基噻吩)(P3HT)具有更低能带结构的聚{[9-(1辛基壬基)-9H-咔唑-2,7-2基]-2,5-噻吩二基-2,1,3-苯并噻二唑-4,7-二基-2,5噻吩二基}(PCDTBT)作为电子给体材料和较C60衍生物(PC60BM)具有更广光谱吸收能力的C70衍生物(PC70BM)作为电子受体材料构建共混体系活性层,制备有机聚合物太阳能电池。通过控制活性层薄膜生长速度、环境得出在N2环境中静置10min时聚合物电池达到了5.65%的高光电转换效率(PCE)。然后,通过进一步优化活性层薄膜厚度短路电流密度大幅提升至14.2mA/cm2,PCE达到5.84%。结果表明,在不使用TiOx等光学间隔层的情况下,通过控制活性层薄膜生长过程和优化活性层薄膜厚度也可以大幅增加短路电流密度,获得高的PCE。     

改性三聚氰胺泡塑富集-电感耦合等离子体质谱(ICP-MS)法测定矿样中的钯

钯的富集常用泡塑作为载体，而通常对泡塑的处理过程需要使用带有胺基的有机试剂，以确保泡塑的官能团带有正电荷，用于富集带有负电荷的钯络阴离子。本文选用10%(V/V)盐酸对三聚氰胺进行处理，该方法泡塑处理过程简单易实现，且对环境友好。样品用HCl-H2O2体系进行消解，避免了NO3-的引入。在盐酸浓度低于10%（V/V），振荡时间为80min时，选择高温灰化法，Pd的回收率可达到 95%以上。以铂族元素国家一级标准物质进行验证，测定值与认定值基本一致。相对标准偏差（RSD）Pd为3.73%~6.76%。可以满足大部分矿样中Pd的分析检测。