微波合成PtRu/C纳米催化剂及其对甲醇电化学氧化性能

PtRu/carbon nanosized catalyst with PtRu loading of 26.4wt% (Rt∶Ru=1.0∶1.0～1.1) was rapidly synthesized by the microwave polyol process employing the ethylene glycol solution of H₂PtCl₆ and RuCl₃ as precursors in the presence of XC-72 carbon support. TEM observations demonstrated that microwave-prepared PtRu nanoparticles were narrowly distributed and highly dispersed on the carbon with an average size of 3.9 nm. Electrochemical experiments showed that microwave-synthesized PtRu/carbon catalyst exhibited very high catalytic activity for electro-oxidation of liquid methanol at room temperature.     

在乳液体系里制备过氧化氫基聚苯乙烯及其在接枝聚合上的应用

用不同分子量的聚苯乙烯在乳液体系中进行过氧化氢基化反应,然后测定这些产品的特性粘数,HPO值(每1,000个苯乙烯结构单元中所合的过氧化氢基平均数目)等。在过氧化氢基聚苯乙烯的红外光谱里,可以在3,200—3,600厘米~(-1)吸收区里观察到过氧化氢基的吸收带,其吸收强度随着HPO值的增大而加强。最后用这些大分子过氧化物引发甲基丙烯酸甲酯及苯乙烯聚合,得到接枝聚合物。经过分离提纯后,用下列的方法: (1)浊度滴定; (2)热机械性能的测试; (3)水解后测定交换量; (4)红外吸收光谱;证明它们是接枝共聚物。     

二茂铁衍生物电子传递剂键合的溶胶-凝胶葡萄糖生物传感器

The sol-gel derived glucose biosensor was developed, and the sol-gel membrane was organically modified by N-（3-triethoxysilylpropyl）-ferrocenylmethylamine （FcSi） as sol-gel precursor to make electrochemical biosensor. The structure of biosensor was sol-gel/FcSi＋GOx/GC type （glucose oxidase, GOx）. The ferrocene mediator was chemically immobilized to the silane network, and GOx was entrapped to the sol-gel glass network. Therefore, these structures prevented mediator leakage and retained the enzyme activity. Additionally, pH of electrolyte, temperature effects, and interference of positive substances with biosensor were investigated. And the electrochemical performance of biosensor was studied by amperometry. The results indicated that the linear range, detection limit. and response slope of biosensor was 2.00×10^-4-1.57×10^-3 mol·L^-1, 2.0×10^-4 mol·L^-1 and 5.06×10^5 nA·mol^- 1·L, respectively.     

A QUANTITATIVE EVALUATION OF ELASTIC WAVE IN SOLID BY STROBOSCOPIC PHOTOELASTICITY

We have developed a method for visually measuring and evaluating stresses emitted from an ultrasonic probe into a model solid similar to the actual material, by using image-processing techniques and stroboscopic photoelasticity. The visualization of wave stress (sound pressure) distribution can be achieved by synthesizing two photoelastic pictures, in which the directions of the principal axes of linear polariscopes are different by 45 degrees. The sound pressure field generated by commercial ultrasonic probes was measured by using the proposed method.     

The effects of external optical feedback on the power penalty of DFB-LD modules for 2.5Gbs−1 optical transmission systems

We report the effects of external optical feedback on the power penalty of commercial distributed feedback laser diode (DFB-LD) modules for 2.5Gbs–1 optical transmission systems. External optical feedback presented to the DFB-LD modules causes the excitation of external cavity modes, resulting in increased relative intensity noise (RIN) and intensity noise ripples at low frequency region below 500MHz. For a 10–10 bit error rate (BER), the minimum power penalty is as much as 1.25dB for a feedback ratio of –8.8dB. An excess power penalty of 0.5dB per 3dB increase in the feedback ratio was also empirically obtained. We suggest that optical isolators in 2.5Gbs–1 DFB-LD modules used in conventional optical transmission systems or WDM systems must have a peak isolation ratio of better than 54.5dB, instead of the previously recommended 30dB, for negligible power penalty induced by external optical feedback.     

ABO3型晶体中氧的电子自发极化

计算O^-2在晶体场中出现的Jahn-Teller效应,得到具有电矩的2p_π3s3d₀杂化原子轨道。BO₆八面体共价性质决定了ABO₃晶体的各种极化相。理论给出P_s比值、钛位移大小和热力学参数ξ′,ζ′均接近于实验结果。统一解释了钛酸钡的三个相转变。相变条件给出七种晶体中氧的屏蔽常数平均值与Slater的值一致。     

晶体管杂系参数与自然等效线路

本文研究面结合型晶体管共发射极线路的小讯号h参数与自然等效线路中元件的关系。根据两种合金管(2N104及Ⅱ-6晶体管)h参数的实验结果求出h参数与自然等效线路元件随频率及随直流运用状态(直流发射极电流及直流集电极电压)的相互关系。对实验结果与根据晶体管物理构造分析计算的结果进行了比较。对开路反向电压放大系数μ_bc的现象给予详细分析,并求出μ_bc与开路输出导纳h₂₂的相互关系。两套晶体管的h参数及自然等效线路的完整资料可供晶体管器件设计及线路研究者的使用。