Bioaccumulation of As(III)/As(V) ions by living cells of Corynebacterium glutamicum MTCC 2745

Significant factors on simultaneous growth and bioaccumulation of arsenic ions by living cells of bacteria, Corynebacterium glutamicum MTCC 2745, were explored in growth media under experimental conditions like pH and concentrations of arsenic ions. Combined effects of the initial concentrations of peptone and arsenic (either As(III) or As(V)) ions on the specific growth rate and arsenic bioaccumulation competence of the bacteria were studied and optimized using the Response Surface Methodology. Optimum combination predicted via RSM demonstrated that the bacteria were capable of bioaccumulating As(III) and As(V) in the growth medium containing 1000 mg/L arsenic and 9 g/L peptone up to 78.4% and 77.6%, respectively.     

A fuzzy reasoning and fuzzy-analytical hierarchy process based approach to the process of railway risk information: A railway risk management system

Risk management is becoming increasingly important for railway companies in order to safeguard their passengers and employees while improving safety and reducing maintenance costs. However, in many circumstances, the application of probabilistic risk analysis tools may not give satisfactory results because the risk data are incomplete or there is a high level of uncertainty involved in the risk data. This article presents the development of a risk management system for railway risk analysis using fuzzy reasoning approach and fuzzy analytical hierarchy decision making process. In the system, fuzzy reasoning approach (FRA) is employed to estimate the risk level of each hazardous event in terms of failure frequency, consequence severity and consequence probability. This allows imprecision or approximate information in the risk analysis process. Fuzzy analytical hierarchy process (fuzzy-AHP) technique is then incorporated into the risk model to use its advantage in determining the relative importance of the risk contributions so that the risk assessment can be progressed from hazardous event level to hazard group level and finally to railway system level. This risk assessment system can evaluate both qualitative and quantitative risk data and information associated with a railway system effectively and efficiently, which will provide railway risk analysts, managers and engineers with a method and tool to improve their safety management of railway systems and set safety standards. A case study on risk assessment of shunting at Hammersmith depot is used to illustrate the application of the proposed risk assessment system.     

基于倒排索引的密文数据库检索方法研究

针对实际密文数据库的应用,在全文检索倒排索引技术的基础上,设计了一种通过密文倒排索引文件对其进行快速检索的方法。密文索引文件中主要包含有索引项、相对应的记录主键等信息。检索时,通过用检索词匹配索引文件中的索引项,找到对应的记录主键集合,再根据记录主键集合查询密文数据库,获取相应的密文数据,进行解密即可获取明文数据信息。整个检索过程中不对数据库进行解密,从而实现了在不解密的情况下对密文数据库的快速检索。     

GF9410U^＊型GaAs发光二极管

本文较详细地叙述了 GF9410U 型 GaAs 发光二极管的结构,工作原理和性能参数,简介了它的用途和在实际中的使用情况。     

Si- and Mg-implanted InP,GaInAs and short-time proximity cap annealing

Si- and Mg-ions with energies of 180 keV have been implanted into semi-insulating InP substrates and low doped n- and p-type GalnAs epitaxial layers (3 · l0¹⁶cm⁻³). Sheet resistances and doping profiles are analyzed and compared with LSS theory. Post-implantation annealing is studied with respect to encapsulation, time and temperature. We have tested as new encapsulation techniques for InP the simple proximity cap annealing and for GalnAs the As-doped spun-on SiO₂. Proximity cap annealing yields decomposition-free surfaces when using a recessed capsubstrate. At annealing temperatures of around 800 °C less activation is obtained than with conventional PSG annealing and a surface accumulation of charge-carriers is established. A time limit of around 3 min is found for Si- and Mg-implanted InP, beyond which the sheet resistance no longer decreases and the doping saturates. For Si in InP, short-time annealing yields to a 68 % activation of carriers, not significantly higher than with conventional long-time annealing. In the case of Si in GalnAs, however, short-time annealing is much more effective. A 100 % activation is obtained for a dose of 2.10¹⁴ cm⁻², while only 7 % is found for long annealing. Even at such a high dose of 1. 10¹⁶cm⁻² we have achieved about an order of magnitude higher activation with short annealing than with long annealing. Most information contained in this paper was presented at the 1984 Electron Materials Conference as paper L-l.     

新型抑制剂DAs分离铜砷

经对高砷铜矿采用石灰、次氯酸钾、高锰酸钾、鞣酸、DAs等不同抑制剂进行降砷试验,结果表明,新型除砷药剂DAs分离铜砷效果最佳,在不影响黄铜矿回收率的前提下,实现了对毒砂的有效抑制.对含砷为6.22%的高砷铜矿浮选试验结果表明,铜精矿砷含量可以降至0.43%,铜回收率为94.46%.     

氢化物发生原子荧光法和无火焰原子荧光法连续测定地球化学样品中的As、Sb、Bi、Hg

建立了一种连续测定Ａｓ、Ｓｂ、Ｂｉ、Ｈｇ四元素的方法。对测汞用还原剂及几种测量体系进行了比较，采用对原子化器适当加温的无火焰原子荧光法测汞，以ＫＭｎＯ４消除Ｔｅ、Ｓｅ对汞测定的干扰。本方法Ａｓ、Ｓｂ、Ｂｉ、Ｈｇ四元素的检出限分别为２．０１×１０－１０ｇ／ｍｌ、１．５６×１０－１０ｇ／ｍｌ、２．９８×１０－１０ｇ／ｍｌ；４．２×１０－１１ｇ／ｍｌ；对ＧＳＳＩ平行测定１１次，Ｈｇ的标准偏差为２．１％；对含Ａｓ、Ｓｂ、Ｂｉ为１０×１０－９ｇ／ｍｌ、１．０×１０－９ｇ／ｍｌ、１０×１０－１０ｇ／ｍｌ的溶液平行测定１１次，其ＲＳＤ分别为１．３７５％、１．３８６％和２．３３９％；经对地球化学标准物质及批量样品分析证明，结果满足要求。     

连续滴定法测定矿石及合金中砷锑含量

用浓硫酸溶样,在一定温度下,先用硫酸铈滴定,再用溴酸钾滴定,可分别计算出Sb和As的含量.该法操作简单、测定快速,相对标准偏差小于1.5%,适用于常规的矿石和合金中砷锑的测定.     

The diffusion of ion-implanted arsenic in thermally grown SiO2

The diffusivity of ion-implanted As in SiO₂ is investigated as a function of the implanted dose, oxide type and ambient in the 1000–1200° C temperature range. The As diffusivity in oxide is extracted, using electrical methods, from the profiles of As diffused into the substrate. Secondary-ion-mass-spectroscopy depth profiles of some of the samples are in agreement with the results of the electrical methods. Two types of oxide are investigated: Dry oxide grown in O₂ and wet oxide grown in steam. The diffusivity is characterized as a function of the temperature for dry oxide annealed in N₂, and for wet oxide annealed both in N₂ and in N₂/H₂ (10%). The measured As diffusivity vs temperature is fitted to a single activation energy exponential model. For the wet-grown oxide, the extracted activation energy for the N₂/H₂ (10%) annealed sample is 4.4 ± 0.5 eV and for the N₂ annealed oxide it is found to be 5.5 ± 0.5 eV. For oxide grown in dry oxygen the As diffusivity is characterized also as a function of the implant dose. It is found to be independent of the implanted dose, for ion energy of 40 keV and dose in the 10¹²–10¹⁵ cm^-2 range, and its activation energy equals 4.7 ± 0.5 eV. The extracted parameters were installed in the SUPREM-III process simulation program and correctly predict ion-implanted As diffusion behavior in SiO₂.     

阿尔金山西部区域化探数据处理方法对比研究

分别采用常规统计法(对数)、EDA法和分形法(含量-频数法和含量-面积法)对阿尔金山西部地区水系沉积物As元素数据进行处理。不同方法所得结果相差较大,其中含量-面积法最大,常规统计法(对数)和EDA法次之,含量-频数法最小。通过对比异常圈定结果及与矿点对比情况认为,常规统计法(对数)确定的异常下限更适合本研究区,其它方法造成异常面积过大或过小,会给异常查证带来困难。因此,在实际工作计算异常下限之前要充分分析其原始数据分布规律,考虑其地球化学数据的分布模式,其次要与实际地质情况相结合,选择较适宜的异常下限计算方法。