A Review: Studies on Uranium Removal Using Different Techniques. Overview

The presence of uranium in soil and underground water generate an important issue against public perception on the risk, which the contamination poses to the environmental and human health. Uranium is the dangerous element found in nature, it found in all rocks with different ratios. As nuclear science developed, nuclear waste containing uranium increased. Contamination reached to soil, underground water and in some cases drinking water which has increased public health concerns due to the chemical toxicity of depleted uranium at elevated dosages. For this reason this review concerned to develop methods for uranium removal from low-grade and contaminated sources. There are several stationary phases and solvents used in uranyl separation process as amines in different type (primary, secondary, tertiary, and quaternary amine), phosphates, acetates, alcohols, phenols and amidoxime resins. The article addresses the main features of the following techniques for uranium: found on soil, chemical processes for separation from contaminated soils and liquor by various suitable solvent, removal by chelating resins, impregnated, and imprinted ones.     

Numerical Aspects in Estimating the Parameters of a Mixture of Normal Distributions

Abstract

Mixtures of normal distributions arise naturally in robustness analyses when distributional assumptions are not met and with the analysis of contaminated data. Typically these analyses involve substantial computational problems. We present some simulation procedures that address these difficulties.     

电子组装中PCBA清洗技术（待续）

清洗对于电子产品可靠性有着非常重要的影响,针对印制电路组件污染物进行了系统阐述,并对不同的清洗技术和工艺进行了总结归纳,讨论了影响清洗效果的各个因素及其检验规范,为实际生产起到指导作用。     

适用于小型生产线运行的单晶圆清洗技术的实现

利用臭氧消毒水和淡氟氢酸清洗技术,使设备生产厂家的单晶圆旋转清洗工艺适应向小型生产线转入的应用,从而使生产周期的缩短成为可能。     

硅片湿法清洗工艺技术及设备发展趋势

简要介绍了硅片湿化学清洗工艺技术及清洗设备结构技术,包括一些典型的槽体结构、干燥工艺技术等.并就清洗技术的发展需要,阐述未来清洗设备的发展趋势.     

A technique for estimating contamination tolerance limits for stable isotope ratio determinations

A model of the interaction between the precision of an isotope ion signal measurement and the accuracy of an isotope ratio determination was developed and used to derive the equations required to calculate the maximum tolerable amount of contamination for stable isotope ratio determinations. Comparison of the calculated tolerance limits and the blank estimated amount of contaminant will establish whether or not a correction for the contribution of the contaminant to the gross signals will be required. The 1000:1 sample-to-contaminant concentration tolerance limit used in stable isotope ratio plasma mass spectrometry will, in some situations, underestimate the contamination error compared to the model calculations.Derivation of the limit equations required an empirically determined relation between the signal strength and the signal's relative standard deviation (signal noise function). A single hyperbolic signal noise function was used to describe the behaviour of isotope ion signals of Ni, Cu, Tl and Pb measured using a plasma source double focusing magnetic sector mass spectrometer. The derivation could be extended to accommodate different signal noise functions.     

熔石英表面铜膜污染物诱导损伤实验研究

 在熔石英元件表面溅射一层厚度小于10 nm的金属铜膜污染物,并测试元件的透过率。测试355 nm熔石英元件的激光损伤阈值,并用光学显微镜观测损伤形态。实验结果表明：污染后的熔石英元件的损伤阈值降低20%左右,元件表面的金属污染物薄膜经强激光辐照,在熔石英表面形成很多坑状微损伤,分布不均的热应力导致表面起伏,并有明显的烧蚀现象,导致基底损伤阈值下降。建立的光吸收和热沉积传输模型初步解释污染物膜层导致熔石英元件损伤的机理。     

A spectrophotometric method to determine the siderophore production by strains of fluorescent Pseudomonas in the presence of copper and iron

A simple procedure to determine levels of siderophore production by strains of Pseudomonas, particularly the Avm strain is described. Bacterial cells were incubated for 24 h in iron-rich (RM) and iron-limiting conditions (RM-Fe) with and without 6 and 60 μM of CuSO₄. Cells grown under iron-limiting conditions developed a green color even in the presence of Cu. The spent media supernatants from the Avm cells grown in RM-Fe medium showed a maximum peak of absorbance at 400 nm, which suggest that this strain produced a single type of siderophore. The presence of 60 μM of CuSO₄ in the cultures did not interfere with the detection of siderophores in the spent media. Clear supernatants obtained from cultures of 10 fluorescent Pseudomonas were diluted 1 to 10 in deionized water and the absorption at 400 nm was determined. The results demonstrated the clear discriminating capacity of this highly practical procedure to categorize a great number of fluorescent Pseudomonas strains by the range of siderophore production.     

香港餐厅的室内空气品质与空调通风

香港地区人口稠密,经济发达,香港市民每日都在餐厅花费较多的时间。餐厅的空气品质对市民的健康产生重要的影响。本文对香港多间中式餐厅室内的二氧化碳(CO2),一氧化碳(CO),氮氧化物(NOx),可吸入尘粒(RSP)等主要污染物浓度进行了监测,以评估其室内空气品质,并结合香港市民日常时间安排调查的结果,揭示了餐厅空气品质与市民健康关系。