Control of sonoluminescence signal in deionized water using carbon dioxide

Megasonic cleaning is routinely employed in semiconductor industry for cleaning of wafers. However, the method also results in damage to wafer features and such damage has been proposed to arise from transient, imploding cavities formed during megasonic processing. Transient cavitation is associated with the release of light, a phenomenon called sonoluminescence (SL) and the extent of damage has been shown to correlate with the intensity of SL. Control of sonoluminescence may therefore allow control of damage during megasonic processing of wafers. In this study, the ability of carbon dioxide to quench sonoluminescence generation in deionized water exposed to megasonic field of varying power density and duty cycle has been systematically investigated. It has been found that CO₂ is not only incapable but also a potent inhibitor of sonoluminescence, providing a potential means for selective alleviation of the violent effects of transient cavitation in process fluids. A novel chemical method has been established for in situ release of CO₂ from NH₄HCO₃ through a pH induced shift in the carbonic acid equilibria in deionized water. Using this method, a precisely controlled, progressive decrease in SL of air saturated deionized water through addition of NH₄HCO₃ has been demonstrated. It has been determined that 130 ppm of released CO₂ is sufficient for complete inhibition of sonoluminescence generated in air saturated deionized water.     

装煤推焦车轨道基础损坏原因分析和解决方案

针对印度工程中出现的装煤推焦车轨道基础损坏,仔细勘察了工程现场,对问题出现的可能原因,从轨道基础设计、车辆使用和现场施工等方面进行了详细的理论分析和计算验证。根据理论分析和计算结果,提出了解决问题的方案。     

The effect of ozonization on furniture dust: Microbial content and immunotoxicity in vitro

Moisture and mold problems in buildings contaminate also the furniture and other movable property. If cleaning of the contaminated furniture is neglected, it may continue to cause problems to the occupants even after the moisture-damage repairs. The aim of this study was to determine the effectiveness of high-efficiency ozone treatment in cleaning of the furniture from moisture-damaged buildings. In addition, the effectiveness of two cleaning methods was compared. Samples were vacuumed from the padded areas before and after the treatment. The microbial flora and concentrations in the dust sample were determined by quantitative cultivation and QPCR-methods. The immunotoxic potential of the dust samples was analyzed by measuring effects on cell viability and production of inflammatory mediators in vitro. Concentrations of viable microbes decreased significantly in most of the samples after cleaning. Cleaning with combined steam wash and ozonisation was more effective method than ozonising alone, but the difference was not statistically significant. Detection of fungal species with PCR showed a slight but nonsignificant decrease in concentrations after the cleaning. The immunotoxic potential of the collected dust decreased significantly in most of the samples. However, in a small subgroup of samples, increased concentrations of microbes and immunotoxicological activity were detected. This study shows that a transportable cleaning unit with high-efficiency ozonising is in most cases effective in decreasing the concentrations of viable microbes and immunotoxicological activity of the furniture dust. However, the method does not destroy or remove all fungal material present in the dust, as detected with QPCR analysis, and in some cases the cleaning procedure may increase the microbial concentrations and immunotoxicity of the dust.     

浅谈桥梁浅基础水毁原因与防治加固对策

从桥位选址、河床自然交迁、人为因素干扰等方面分析了桥梁常见水毁病害的成因,在此基础上归纳了新建桥梁的预防措施,探讨了老桥基础的防治对策,指出应坚持预防为主、综合治理的原则,加强施工管理,确保桥梁安全运行。     

照明的明天：什么是热点

从社会、产品和应用的角度,举例说明未来数年照明的＂热点＂。从社会的角度,说明可持续发展以及相关节能产品和应用设计的持续重要性。要更加关注完全无废料的设计,即＂从摇篮到摇篮＂（from cradle to cradle）的设计。从产品的角度,说明固态将成为许多产品应用的标准。在固态照明方面,由于所提供的数据常常有误而令新用户不满,因此向固态照明转变的脚步会放缓。若有效控制固态照明中的眩光,须有新型的光学设计。目前的评价体系,是通过经验方法获得,完全不适用于固态照明环境,因此需要全新的眩光评价体系。普通室内照明的显色性和色表规格,过去以白炽灯为基准,现在须设定严格的新标准。在应用方面,若要达到非视觉生物效应,智能动态照明也要成为一种标准。我们将看到,为减少因生物钟失调而出现的问题,会广泛应用光学治疗。在固定路灯方面,随着汽车系统本身的发展,不会再优先考虑物体的能见度。我们需要的不再是路灯亮度概念,而是更加三维的概念。若综合考虑中间视觉的所有效果,路灯光源的最有效光谱应该偏暖白光。老年人会丧失短波长视觉能力,是其中的主要原因。     

新型纳米尺寸MOSFET器件的模拟和设计

在半导体器件的研制过程中,用计算机数值模拟取代测量方法来优化设计器件的性能参数,则器件的调试周期将显著缩短,费用将大幅度降低。本文简述了新型纳米尺寸MOSFET器件模拟的主要物理模型和数值方法,阐述MOSFET相关器件模拟的国内外研究动态,判断其发展趋势和研究方向。     

Changes during heating in chemical composition and in-vitro digestion of four commodities

The effects of duration of heating on the composition and digestibility of whole cotton seed, almond hulls, whole pressed safflower seed and alfalfa were studied. The four commodities were heated at 125°C from 0 to 120 h. Nitrogen and ash values were relatively stable across commodities and heating times. However, acid detergent fibre, neutral detergent fibre, in-vitro neutral detergent fibre remaining after 48 h fermentation and acid detergent insoluble nitrogen increased hyperbolically, approaching a relatively constant value at long heating times for all commodities. The sensitivity of each commodity to heat damage was different, and the rate that each analysis value approached a relatively constant value differed across commodities. In general, alfalfa was the most sensitive and whole cotton seed the least sensitive for a given nutrient change with heating time. Also the amount of neutral detergent fibre digested approached a relatively constant value at longer heating times for whole cotton seed, whole pressed safflower seed and alfalfa while approaching zero for almond hulls. Prior analysis of an unheated commodity is necessary to utilise compositional analyses to determine heat damage.     

磁滞及磁饱和效应对磁光光纤传感器的影响

给出了ＩｎＢｉＣａＶＩＧ晶体的磁滞回线,详细分析了磁滞及磁饱和效应对磁光光纤传感器的影响。当所测磁场信号为交变量时,磁滞的影响主要是相位延迟,对幅度及频谱分布影响较小;饱和效应不仅使响应幅值减小,同时还导致明显的频谱变化。     

聚焦平台光束大气传输光束扩展的定标参数分析

建议采用63.2%环围能量半径及其内平均功率密度描述激光器大气传输光斑扩展特性.通过利用数值模拟及实验观测相结合的方法,对聚焦平台光束大气传输线性效应及湍流热晕相互作用引起的光束扩展进行了大量的数值模拟及部分实验研究,建立了描述聚焦平台光束大气传输光束扩展与大气传输特征物理参量的定标关系,从而为激光工程应用的可行性及系统参量的优化设计提供依据.     

ESD与EMP对微波晶体管损伤机理研究

主要论述了电子装备中易受静电放电(ESD)和电磁脉冲(EMP)损伤的微波半导体器件的失效模式和失效机理.实验与理论分析结果表明,电流放大系数hFE是ESD、EMP损伤的敏感参数;在ESD、EMP的作用下,器件进入雪崩击穿状态(反偏注入),从而诱发热电子注入效应,使hFE逐渐退化;BC结反偏时的失效能量低于EB结反偏时的失效能量,BC结是EMP损伤的较易损端口;改进器件的结构设计、提高器件抗ESD、EMP能量,可有效提高电子装备抗电磁脉冲的可靠性水平.