LED城市照明示范工程应注意的问题

该文主要介绍了半导体(LED)在城市照明示范工程应用中应该注意的一些问题。论文包含有LED的性能和特点、科技部十城万盏半导体照明示范工程的要求及内容、示范工程应遵循的设计标准、LED照明器具应满足的技术要求等。     

Introduction to School of Environmental science and Engineering of North China Electric Power University

<正>Along with the fast development of national economy, environmental issues have become more and more prominent. China has promulgated a series of policies of energy-saving and emission-reduction to slow     

区域文化生境下地方大学的文化选择

当前地方大学在发展自身的同时,也要立足地方、服务地方。本文试图用阿特巴赫的中心—边缘学说和生物学上的生态位学说来分析地方大学的发展困境,提出对策,立足地方大学优势,从文化生态学角度来探讨区域大学的特色和发展方向,并更好地服务地方发展。     

高校毕业班“空巢现象”调查与研究

针对目前高校毕业班空巢现象较为严重的现状,通过对某些高校毕业班的调查,分析了高校毕业班空巢现象出现的原因和危害,提出了防止空巢现象的策略,以期能够达到提高高校毕业班教学质量的目的。     

英语课堂中的文化教学技巧与方法

外语的学习实际上就是对另外一种文化的学习,但文化信息传递却是我国的外语教学中相对薄弱的环节.笔者根据自己的留学经历与教学经验,提出了几种切实可行的教学方法,如文化岛、文化胶囊、文化吸收、文化误解分析、话剧表演、记录法、小测试、观察体态语等.这些方法易于操作,穿插在课堂教学中,容易引起同学们的兴趣并能提升他们对文化的敏感度和跨文化交流的意识.     

铁通公司FTTH发展与建设思考

本文从FTTH发展思路、应用场景、建设模式等方面进行阐述,并对铁通公司FTTH下一步发展提出4点建议。     

Occurrence and characteristics of Vibrio vulnificus in retail marine shrimp in China

Vibrio vulnificus is a gram-negative bacterium that naturally occurs in estuarine waters and marine environment. Consumption of seafood contaminated with V. vulnificus or exposure to the contaminated water causes septicemia, gastroenteritis or wound infections in humans. This study aimed at identifying the prevalence of V. vulnificus in shrimps in Chinese seafood market. From June to September 2009, 239 samples encompassing six shrimp species were collected from ten cities in China. To quantify the prevalence and the levels of V. vulnificus in shrimps, the most probable number (MPN) method was used combining with the polymerase chain reaction (PCR) which was used to classify the isolates by detecting V. vulnificus hemolysin gene (vvhA). One hundred and forty out of 239 samples were positive for V. vulnificus, with the geometric mean level at 153.3 MPN/g. The prevalence and levels of V. vulnificus in shrimps varied in different geographic areas, with the values for the samples in the South cities (179.6 MPN/g) remarkably higher than that in the North cities (7.6 MPN/g). In addition, we found that 61.7% (79/128) of the V. vulnificus positive samples contained C-type (Clinical) strains and 8 contained E-type (Environmental) strains. The antimicrobial susceptibility of the isolates to 12 antibiotics was tested as well. Most of the 169 isolates remained susceptible to the majority of antimicrobials tested, whereas some strains tend to be less sensitive to amikacin, ampicillin, tetracycline and gentamicin. In conclusion, V. vulnificus is commonly found in retail marine shrimp in Chinese seafood market, and most of the shrimp samples contained C-type strains, which may pose a potential threat to human health.     

Baushinger’s Effect in Wear of Materials

The response of Cu–40%Zn alloy to wear during unidirectional and bidirectional abrasion processes was investigated. It was observed that the mass loss of the alloy decreased as the number of times of changing the sliding direction was increased. Corresponding to this decrease in mass loss, hardness of the worn surface increased initially and then decreased. Cracking in the surface layer was analyzed to get an insight into the mechanism involved. Results of the study suggest that Baushinger’s effect played a role when the sliding direction was alternated.     

A Follow-up Study on Bauschinger’s Effect in Bidirectional Wear of Cu-40%Zn against Different Types of Counter-Face

Previously, we demonstrated a decrease in wear loss of Cu-40%Zn against a steel wheel during bidirectional sliding ascribed to Bauschinger’s effect associated with diminished strain-hardening. However, the situation changed when the alloy was worn by a ceramic-grinding wheel. It was observed that the mass loss continuously increased with reversal of the sliding-direction although the corresponding hardness of worn surface also decreased. In this case, Bauschinger effect still functioned but the failure mode varied, leading to the different trend of response to wear against the ceramic-grinding wheel in comparison with that against the steel counter-face.