Ultrafast multiplex CARS investigation of vibrational characteristics in chloroform and PMMA

This paper demonstrates the femtosecond time-resolved coherent anti-Stokes Raman scattering by using folded BOXCARS geometry where an ultrashort broadband coherent white light continuum was used as Stokes pulse, and carries out the non-contact detection at long distance. The CARS signal is so easy to be detected that it can be seen even by nude eye. The C--H bonds of chloroform or PMMA were detected and the vibration modes belonging to the side chain and the main chain in PMMA were also compared. Their vibrational characteristics involved decay process and quantum beating were discussed. This modified CARS experimental technique could make up the deficiency of traditional CARS technique.     

输出功率为21.5W的单端抽运Nd:YVO4/LBO单频激光器

采用中心波长为888nm的激光二极管作为抽运源,减轻了Nd:YVO4晶体中的热效应。通过合理的谐振腔设计,扩大激光晶体处的基模尺寸和振荡光在凹面腔镜处的入射角,减轻了激光晶体内部的热效应和谐振腔像散,提高了激光器的输出功率。采用四镜环形腔选模的办法,获得稳定的高功率单频激光输出。在吸收的抽运功率为67.5W时,实现了最高功率为21.5W的532nm单频激光输出,其8h功率稳定性优于±1%,光束质量M2<1.1,光-光转换效率为31.9%。     

GexSi1—x／Si应变层超晶格的结构特性与器件应用

近年来,Ge_xSi_(1-x)/Si 应变层超晶格的研究日渐活跃与成熟。本文试从半导体物理与器件应用的角度出发,着重介绍了这种超晶格的各种结构特性,并简要评述了以 Ge_xSi_(1-x)/Si 异质结形成的各种新型半导体器件的研究进展。     

一种测定钢表面裂纹深度的涡流检测技术

采用涡流法检测钢表面的缺损状况和裂纹深度.设计和制作了双线圈涡流传感器和检测电路.并确定了裂纹深度与响应电压的关系曲线.     

基于有线电视的红外系统在听力考试中的应用

首先介绍了几种常用外语听力考试的方法及各自的优缺点,再次重点介绍了广东外语外贸大学北校区基于有线电视的红外系统在听力考试中的应用,最后对红外听力系统的使用进行了展望。     

中国电信运营商技术创新国际化模式探析

为最大化利用发达国家技术集聚地的外溢效应，我国电信运营商应加速推进技术创新国际化。本文分析了技术创新国际化的内涵和动因，以法国电信．DoCoMo和沃达丰为例阐释了国外先进运营商技术创新国际化的模式，剖析了中国电信运营商技术创新国际化的现状和问题，最后提出了中国电信运营商技术创新国际化的几点建议，包括技术创新国际化先于市场国际化，以核心技术推动技术创新国际化，以及适合现阶段的技术创新国际化模式。     

拉曼光谱分析人类单个血小板的类胡萝卜素

应用拉曼光镊对人的单个血小板细胞(Plt)进行拉曼光谱收集与分析.拉曼信号显示,人类血液成分中,血小板的类胡萝卜素浓度最高.虽然类胡萝卜素在人类血小板中普遍存在,但是单个血小板之间差异极显著,且与血小板的脂类物质、蛋白质含量没有相关性.血小板激活过程引起蛋白质拉曼光谱的变化,而类胡萝卜素基本没有变化;常温(25℃)保存...     

In Situ Tests of Multiwalled Carbon Nanotubes with Strength Close to Theoretical Predictions

Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging is used to directly determine the number of fractured shells and the ehirality of the outer shell. Electron irradiation at 200keV for 10, 100 and 1800s lead to improvements of the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. This procedure is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanodevices.     

试论新形势下如何做好电力设施保护工作

电力生产是关乎到国民生计的重要产业,电力产业中,电力设施是重要的社会公用设施,是电力生产过程中,输送和供应的重要传送带.电力设施的正常运行是保障用电安全、维护公共安全的重要前提,关乎到社会生产的正常运行和社会秩序的有序进行.在新的发展形势下,对电力设施的保护工作应该更加重视.本文就电力设施保护目前存在的问题进行了简要分析,并且对新形势下的保护工作进行了一些研究.