It is well-known that the properties of semiconductor materials including gallium arsenide are controlled by defects and impurities.
The characterization of these defects is important not only for better understanding of the solid state phenomena but also
for improved reliability and performance of electronic devices. We have been investigating the defects in gallium arsenide
for several years using deep level transient spectroscopy, photoconductivity, transient photoconductivity, photoluminescence
etc. Results drawn from our recent studies are presented here to illustrate some of the problems concerning transition metal
impurities, process-induced defects, occurrence of intracentre transitions and metastability of deep levels in gallium arsenide. 相似文献
在分析了工业焊接X光图片特点的基础上,本文应用随机过程和随机几何学、光学成像及信号处理的理论,为该类图片选用一种参数统计模型,并解决了 Wiener 滤波器设计中的一系列问题,应用统计同志滤波的数字处理法,得到了用一些常用方法难以得到的增强效果,从而为寻求工业焊接X光图片的数学模型及增强方法进行了一次有意义的探索。 相似文献
A new catalytic method was developed for photo‐oxidizing the methyl group on aromatic heterocycles such as benzothiazole, benzoxazole, and quinoline to produce the corresponding aldehyde. This is the first report of the metal‐free catalytic synthesis of benzothiazole‐2‐carboxaldehydes using molecular oxygen as the terminal oxidant.
Polymersomes are vesicles whose membranes are comprised of self-assembled block co-polymers. We recently showed that co-encapsulating conjugated multi-porphyrin dyes in a polymersome membrane with ferritin protein in the aqueous lumen confers photo-lability to the polymersome. In the present study, we illustrate that the photo-lability can be extended to vesicles containing dextran, an inert and inexpensive polysaccharide, as the luminal solute. Here we explore how structural features of the polymersome/porphyrin/dextran composite affect its photo-response. Increasing dextran molecular weight, decreasing block copolymer molecular weight, and altering fluorophore-membrane interactions results in increasing the photo-responsiveness of the polymersomes. Amphiphilic interactions of the luminal encapsulant with the membrane coupled with localized heat production in the hydrophobic bilayer likely cause differential thermal expansion in the membrane and the subsequent membrane rupture. This study suggests a general approach to impart photo-responsiveness to any biomimetic vesicle system without chemical modification, as well as a simple, bio-inert method for constructing photo-sensitive carriers for controlled release of encapsulants. 相似文献
