利用钐掺杂氧化铈提高燃料电池阳极活性

用浸渍法制备并采用交流阻抗、极化等技术考察了不同组成的Ni-Sm3＋掺杂的CeO2(SDC) 复合镍阳极的电化学性能及相应电池的功率输出性能.结果表明，SDC掺入镍阳极后,阳极极化过电位及电池的欧姆电阻显著减小.其中阳极过电位的减小与SDC掺入镍电极引起的三相界扩展有关，但SDC的掺入同时引起了电极反应活化能的增加,造成低温下Ni-SDC的极化过电位大于纯Ni电极.高温下,Ni-SDC阳极的阻抗谱由两个半圆组成，其中高频半圆随着SDC掺入量的增加而减小,而低频环与SDC的掺入量基本无关.低温下只观察到一个高频环.高频环可能对应三相界反应,而低频环可能对应氢的解离吸附及扩散.75％（w）Ni-25％（w）SDC/La0.9Sr0.1Ga0.8Mg0.2O3(LSGM)/Sm0.5Sr0.5CoO3(SSC)在所研究的电池中具有最大功率输出密度，其值在1073、973、873 K下分别达到1.1、0.43、0.14 W•cm－2.     

Gorenstein AC亏范畴*

作者定义了Gorenstein AC导出范畴 D^b_gac(R)并且和导出范畴作了一些比较.作者定义了Gorenstein AC奇点范畴 D^b_gacsg(R),在这个范畴中具有有限Gorenstein AC- 投射维数的模都是零对象.同时, 作者给出了由Gorenstein AC- 投射模构成的稳定范畴到奇点范畴的三角嵌入 F : GAC → D^b_sg(R) .通过作函子 F 的商引入Gorenstein AC亏范畴 D^b_gacd(R),并且给出三角等价 D^b_gacd(R) = D^b_gacsg(R)     

A Systematic Evaluation of Polyurethane as a Conformal Coating for the Inhibition of Corrosion on Electronic Components

The corrosion of printed circuit boards can be effectively prevented with a polyurethane conformal coating. In this study, the protective performance of PU coating was investigated systematically through electrochemical measurements and simulated exposure/immersion tests. Some fungi tests were also included. All experimental results show that a polyurethane coating effectively inhibits corrosion on printed circuit boards. The optimal thickness of the coating film should be about 60 μm. Long-term exposure tests showed that this coating material could preserve the reliability of the investigated printed circuit boards for more than 400 days in a 90% relative humidity environment at 25°C.     

旋转铂盘电极上Cu(phen)_2~(2 )与6-巯基嘌呤的相互作用

在Tris-NaC1*(pH=7.2)缓冲溶液中,应用循环伏安法,微分脉冲伏安法、旋转圆盘电极实验、交流阻抗法及其数据模拟等技术研究了Cu(phen)2 25(phcn=1.10-邻菲咯啉)与6-巯基嘌呤(6-MP)的相互作用.结果显示.Cu(phen)2 2MP与6-MP无论在扩散控制过程或电化学控制过程都发生了相互作用.Cu(phen)2 2及其与6-MP的作用产物于铂电极上均呈现一对氧化还原峰,但后者呈现的氧化还原峰负移.峰电流减小.交流阻抗结果显示,无论6-MP存在与否,Cu(phen)2 2在交流阻抗谱上均呈现两个清晰的电容弧,但当6-MP存在时,电化学反应电阻和电化学吸脱附电阻均增大.Cu(phen)2 2在不同转速下的阻抗拟合结果显示.随转速增大.电化学反应电阻和电化学吸脱附电阻均减小.双电层电容呈增大趋势,而吸脱附电容呈减小趋势:当6-MP存在时.仍然呈现此变化规律.     

Li/富锂钒青铜(Li_6V_6O_(15))二次电池正极材料研究

近年来,人们对二次锂电池的正极进行了不少研究。许多过渡金属氧化物或硫化物,如V_6O(13),Li_(1+x)V_3O_8,TiS_2,MoS_2等被认为是较好的正极材料。Pistoia等研究了Li_(1+x)V_3O_8钒青铜的电化学性能得出,当Li浓度高时,由于电子定域作用使电荷屏蔽效应     

THE ESTABLISHMENT OF TWO SETS OF ALIEN ADDITION LINES OF WHEATWHEATGRASS

The procedure and method for the transfer of two sets of 14 pairs of wheatgrass (Agropyron interrnedium) chromosomes into common wheat to establish two sets of wheat-wheatgrass alien addition lines are reported. Meanwhile, observations and analyses have been made on the phenotypicaI characters of all the 14 alien addition lines established. It is determined that wheatgrass chromosomes in some of the established addition lines carry the rustresistant genes. In addition, questions concerning the location and distribution of certain agriculturally important genes of wheatgrass chromosomes have been discussed.     

New far infrared laser lines obtained by optically pumping13CD3OD

We have obtained laser action on 34 far infrared lines for the first time in fully deuterated methyl alcohol with the¹³C isotope (¹³CD₃OD), and we have measured the frequency of 13 lines. The molecule was pumped by a cw CO₂ laser. We have measured the wavelength, the relative polarization, the relative intensity of most lines, the frequency, and the CO₂ pump frequency offset of the strongest lines. The new lines are distributed in the wavelength region from 75.27 m to 464.7 m.Supported in part by a joint grant with the U.S. National Science Foundation grant # INT 80-19014 and the Brazilian Conselho Nacional de Pesquisas (CNPq).     

Dislocation Analysis for Large-sized Sapphire Single Crystal Grown by SAPMAC Method

In this paper,large-sized sapphire (230×210 mm,27.5 kg) was grown by SAPMAC method (sapphire growth technique with micro-pulling and shoulder-expanding at the cooled center). Dislocation peculiarity in large sapphire boule (0001) basal plane was investigated by chemical etching,scanning electron microscopy and X-ray topography method. The triangular dislocation etch pit measured is 7.6×101～8.0×102 cm-2,in which relative high-density dislocations were generated at both initial and final stages of crystal growth. The analysis of single-crystal X-ray topography shows that there are no apparent sub-grain boundaries; the dislocation lines are isolated and straight. Finally,the origins of low-density dislocation in sapphire crystal are discussed by numerical analysis method.     

Electrosorption of sodium cellulose sulfates with different substitution patterns

Various types of sodium cellulose sulfate (SCS), dissolved in a 1M LiCl solution, were investigated by alternating current (AC)polarography. The SCS samples differed in the degree of substitution (DS), thedistribution of substituents within the anhydroglucose unit (AGU), and alongthechain, due to the method of synthesis. The goal was to study theelectrosorptionbehavior, characterized by the shape of the desorption wave in the polarogram,as a function of the chemical structure of the SCS samples. The shape of thedesorption wave reflects domains of different substitution. A superimpositionofparameters like DS and pattern of substitution on the electrosorption behaviorwas observed. The AC polarography method described can be used as a tool todistinguish between an even or uneven distribution of substituents along thecellulose chain.