EFFECT OF THERMAL TREATMENTS ON THE SUPERCONDUCTIVITY OF UNDOPED AND WO3 DOPED Y-Ba-Cu-O SYSTEM

Undoped and WO₃-doped Y-Ba-Cu-O ceramics have been slowly cooled in flowing oxygen or quenched in air from 900℃ to room temperature, after sintering at 900℃ for 3Oh in flowing oxygen. The ac susceptibility measurements show that the T_c of the quenched WO₃-doped Y-Ba-Gu-O superconductor can reach 88K, while the undoped Y-Ba-Cu-O ceramic quenched in air is a non-superconductor. X-ray diffraction data show that WO₃ does not enter into the YBa₂Cu₃O_7-x lattice but forms all impurity phase. The WO₃-doped YBCO specimens quenched in air consist of orthorhombic YBa₂Cu₃O_7-x phase and an impurity phase which increases with increasing WO₃ content. Raman spectra chow that oxygen contents are different for undoped and WO₃-doped samples. It la suggested that suitable doping with WO₃ can change the oxygen content and reduce the effect of thermal treatments on the superconductivity of Y-Ba-Cu-O system.     

肽脱甲酰化酶抑制剂的合成及其抑菌活性

通过对肽脱甲酰化酶抑制剂构效关系的研究,以放线酰胺素为先导化合物,设计并合成了一系列异噁唑类化合物。其结构经1H NMR,IR,MS和元素分析表征。生物活性实验表明,该类化合物对标准肺炎克雷白球菌有显著的抑菌活性。     

1kA级铋系高温超导模型电缆的研制

我们研制了一根１０００Ａ级铋系高温超导模型电缆。电缆由不锈钢波纹管骨架、导体层、层间绝缘和外绝缘绑扎带组成。电缆的导体层由６层共１７１根Ｂｉ－２２２３／Ａｇ多芯带材绕制而成,电缆外径为４５．２ｍｍ,长度为１ｍ。在液氮下的通电实验表明,电缆的临界电流超过１１８０Ａ（１μＶ／ｃｍ判据）,接头总电阻小于０．０６μΩ,均超过设计指标。经两次热循环实验,电缆的临界电流仅退化２．７％,在半小时传输电流１ｋＡ的