正确选择使用防盗水型锅炉专用药剂降低运行费用

正确合理使用防盗水型锅炉专用药剂控制供热系统失水是一项十分有益的节能措施，本文就如何选择和鉴别药剂，如何正确合理使用药剂及相应的经济分析方法作了简单的介绍。     

锅炉专用药剂的正确选择使用

正确合理使用防盗水型锅炉专用药剂控制供热系统失水是一项十分有益的节能措施，本文就如何选择和鉴别药剂，如何正确合理使用药剂及相应的经济分析方法作了简单的介绍。     

水流平衡阀在空调水系统中的合理使用

简述在空调水系统中如何利用线算图合理选择和正确使用水流平衡阀的方法。     

保证白蚁防治药剂有效性的方法

化学药剂防治在我国白蚁防治工程中仍然占主导地位,白蚁防治药剂的有效性是白蚁防治工程质量的根本保证。迄今为止,白蚁防治上主要都是利用现成的农药进行开发和应用。我们使用的白蚁防治药物主要剂型为乳油、悬浮剂、水乳剂、微乳剂、饵剂、粉剂。正确的保管、储存和使用各种不同剂型的药物对保持药剂的有效性起到致关重要的作用。     

如何正确使用混凝土膨胀剂

根据我国混凝土膨胀剂使用中存在的问题 ,提出如何正确使用膨胀剂的意见。必须重视膨胀剂质量 ,确立以限制膨胀率为目标的补偿收缩混凝土配合比设计方法 ,改善结构设计中的合理配筋和加强施工管理 ,才能使混凝土膨胀剂较好地解决建筑结构的裂渗控制问题。     

EPS应急电源及其选用

介绍了EPS应急电源的工作原理和系统组成，并列出了EPS与柴油发电机的区别及其在使用方面的优缺点，最后在如何正确合理选择EPS方面给出了建议。     

谈数控机床的使用与维护

中国已逐步成为世界制造业强国,数控机床的应用也越来越广泛,但人们对这些高科技的设备往往更多地是看重其效能,不仅对合理地使用不够重视,更对其保养及维护工作关注太少,从而缩短机床的使用寿命.本文根据多年的工作经验,就如何正确使用数控机床、如何对其进行有效的维护等方面作了详尽的阐述.     

西药药剂的合理应用及管理

目的:浅析西药药剂的合理应用以及管理措施。方法:选择本院药剂科2012年1月-2013年2月100张西药药剂处方做为研究对象。根据处方应用中出现的问题给予相应的西药药剂管理措施,然后考核。再于2013年3月-2014年4月抽取100张西药药剂处方,比较分析经过管理及应用后的实际用药情况。结果:给予合理管理应用前临床合理用药率为70%,经过合理的管理应用后临床合理用药率为93%,考核后的临床合理用药率明显优于考核前,差异具有统计学意义(P<0.05)。结论:对西药药剂进行合理的应用管理后,可以明显提高临床合理用药率。     

浅谈兽医诊疗中药物的合理配伍及使用方法

兽医诊疗中,药物的合理配伍及正确使用是非常重要的。药物的合理配伍和正确使用能够保证在兽医诊疗过程中的医治效果,促进兽医诊疗事业的发展。对于临床的兽医诊疗,药物的合理配伍以及使用方法都有独到之处,笔者根据自己从事兽医诊疗多年工作经验,从兽医诊疗药物的合理配伍方面进行研究,并对药物的科学使用方法提出了建设性建议。     

简述天然气长输管道工程投资编制

本文通过对长距离输送管道工程作业流程及相应指标定额的介绍,探讨在投资估算编制过程中如何理解并正确使用相关的指标及定额,以及在使用中应该注意的问题,确保编制出的估算文件能够更合理、准确地反映项目建设投资水平。     

化学危险品仓库的安全防火探讨

化学危险物品仓库是指一些专门用于存储易燃易爆化学品的区域,常见的化学危险物品有化学试剂、化学农药等,这些物品存放到仓库中容易发生爆炸、火灾,此时就要落实化学危险物品仓库的防火技术,这样才能提高化学危险物品仓库使用过程中的安全性.文章主要探讨化学危险物品仓库中防火技术的应用.     

Techno-economic evaluation of membrane filtration for the recovery and re-use of tanning chemicals

The majority of pollution generated from leather manufacturing can be contributed to the inefficiency of chemical use in leather processing and to organic substances derived from the hides during processing. In particular, the overall tanning processes performed in drums can be characterized by a high consumption of water and chemicals, most of which are found in the final wastewater. To ensure full penetration and reaction of chemicals with collagen, chemicals are added in excess and are only partly up-taken by the leather. Significant savings of chemicals can be achieved by recovery and recycling of chemicals and water from part streams, thus reducing environmental impacts.This research formed an integrated approach to investigate and exploit the potential of a closed loop operation for various part streams of tanneries. Each of the process streams was separately collected, treated and purified by membrane technologies to obtain a recyclable liquor which can be re-used operationally. In this way a complete recovery of process liquors can be achieved for immediate operational re-use.Membrane technology has been applied to recover chemicals from un-hairing, vegetable tanning, chrome liquors and to polish saline part streams for re-use. By applying membrane filtration up to 90% of the treated liquors can be recovered giving a remaining concentrate volume of only 10%. The permeate obtained from several process areas contained to a high extent chemicals, which were re-used for leather processing.     

Chemicals which cause birth defects--teratogens: a special concern of research chemists

Women who are research chemists suffer an unusually high risk of being exposed to teratogenic chemicals (chemicals which cause birth defects) for the principal reason that they spend a good share of their lives in the laboratory in contact with wide variety of chemicals including new chemicals which may be unsuspected teratogens. Women research chemists therefore need to be able (a) to recognize known teratogens and (b) to predict teratogenicity of a compound that has not been tested. This article discusses these two points with an emphasis on the following topics: how to obtain information on teratogenicity of chemicals; how to interpret teratogenicity data from the literature; and how to make an educated guess about the teratogenicity of chemical compounds.     

Comparative toxicity of ten organic chemicals to ten common aquatic species

The susceptibilities of 10 aquatic organisms to 10 organic chemicals were determined using lethality tests. The species included six fishes, two crustaceans, a chironomid and an amphibian. The chemicals were selected to span the toxicity range from 26 g l⁻¹ to 1 μg l⁻¹ and include chemicals which were lethal by four modes of toxic action. There was no consistent relative susceptibility among the test species because the sensitivity to specific modes of toxic action varied among the chemicals. Nonetheless, the toxicities of the chemicals to any given species were highly correlated to the toxicities to other species, particularly among fishes. The 96-h median lethal concentration (LC₅₀) of the chemicals to rainbow trout (Salmo gairdneri) could be estimated from the 96-h LC₅₀ with fathead minnows (Pimephales promelas) with a correlation coefficient greater than 0.99. Equations for estimating the lethal concentration of chemicals with each species from the 96-h LC₅₀ for fathead minnows are presented.     

Chemical dosing for sulfide control in Australia: An industry survey

Controlling sulfide (H₂S) production and emission in sewer systems is critical due to the corrosion and malodour problems that sulfide causes. Chemical dosing is one of the most commonly used measures to mitigate these problems. Many chemicals have been reported to be effective for sulfide control, but the extent of success varies between chemicals and is also dependent on how they are applied. This industry survey aims to summarise the current practice in Australia with the view to assist the water industry to further improve their practices and to identify new research questions. Results showed that dosing is mainly undertaken in pressure mains. Magnesium hydroxide, sodium hydroxide and nitrate are the most commonly used chemicals for sewers with low flows. In comparison, iron salts are preferentially used for sulfide control in large systems. The use of oxygen injection has declined dramatically in the past few years. Chemical dosing is mainly conducted at wet wells and pumping stations, except for oxygen, which is injected into the pipe. The dosing rates are normally linked to the control mechanisms of the chemicals and the dosing locations, with constant or profiled dosing rates usually applied. Finally, key opportunities for improvement are the use of mathematical models for the selection of chemicals and dosing locations, on-line dynamic control of the dosing rates and the development of more cost-effective chemicals for sulfide control.     

Quantitative structure-pharmacokinetic relationship modelling.

This article presents the current methods in quantitative structure-pharmacokinetic relationship (QSPkR) modelling along with examples using chemicals of toxicological significance. The common method involves: (i) collecting pharmacokinetic data or determining pharmacokinetic parameters (e.g. elimination half-life, volume of distribution) by fitting to experimental data; and (ii) associating them with the structural features of chemicals using a Free-Wilson model. Such QSPkRs have been developed for a few series of chemicals but their usefulness is limited to the exposure scenario and conditions under which the experimental data were originally collected. The alternative approach involves the development of quantitative structure-property relationship (QSPR) models for parameters, blood:air partition coefficient, tissue:blood partition coefficient, maximal velocity for metabolism and Michaelis affinity constant, of physiologically-based pharmacokinetic (PBPK) models which are useful for conducting species, route, dose and scenario extrapolations of the tissue dose of chemicals. Mechanistic QSPRs are available for predicting tissue:blood and blood:air partition coefficients from molecular structure information of chemicals, whereas such approaches are not currently available for hepatic metabolism parameters. However, at the present time, the pharmacokinetics of inhaled volatile organic chemicals can be simulated adequately by considering the physiological limits of the hepatic extraction ratio (0-1) and molecular structure-based estimates of partition coefficients in the PBPK model. This current state-of-the-art of structure-based modelling of pharmacokinetics will advance with the development of QSPRs for other chemical-specific parameters of PBPK models. Integrated QSPR-PBPK modelling should facilitate the identification of chemicals of a family that possess desired properties of bioaccumulation and blood concentration profile in both test animals and humans.     

Critical loads of acidity for surface waters in China

Various types of partition coefficients have been used to facilitate the prediction of the concentration of pollutants in different phases in the environment. Many thousands of chemicals may exist in our environment which makes prediction work difficult or impossible due to a deficiency of knowledge of those unfamiliar compounds. In this study, the correlation between an octanol-water partition coefficient (Kow), water solubility (S) and a normalized soil/sediment partition coefficient (Koc) was investigated though the examination of 148 model chemicals. These model chemicals were classified into five major categories for easier adoption in future use. They are aliphatic compounds, aromatic compounds, pesticides, herbicides and polyaromatic hydrocarbons (PAH). Linear models are developed to correlate these partition coefficients in each category. The prediction of unfamiliar chemicals in the same category becomes possible if the fundamental properties of these chemicals (such as solubility) are previously known.     

A rapid method for determining the toxicity of chemicals to activated sludge

This paper reports the development of a method to determine the toxicity of chemicals to activated sludge. In the method, activated sludge was exposed to various concentrations of test chemicals and the inhibition of [¹⁴C]glucose uptake was measured after 15 min. Data for the decrease in glucose uptake as a function of the log of the test chemical concentration was analyzed by a nonlinear regression model to determine the concentration of chemical inhibiting uptake by 50% (IC₅₀ value). In control experiments, glucose uptake in the absence of test chemicals was rapid, specific and totally dependent on the presence of metabolically-active activated sludge. However, uptake in the presence of inorganic and organic test chemicals showed significant, dose-dependent decreases as the concentration of test material increased. Inhibition of uptake was accurately described by the nonlinear regression model, and calculated IC₅₀ values for two chemicals, mercuric chloride and 3,5-dichlorophenol, agreed well with values reported in the literature to adversely affect wastewater treatment plant operation. Based on the results of our studies, inhibition of glucose uptake proved to be a rapid, accurate and reproducible method of determining the toxicity of chemicals to activated sludge.     

Elimination kinetic model for organic chemicals in earthworms

Mechanistic understanding of bioaccumulation in different organisms and environments should take into account the influence of organism and chemical depending factors on the uptake and elimination kinetics of chemicals. Lipophilicity, metabolism, sorption (bioavailability) and biodegradation of chemicals are among the important factors that may significantly affect the bioaccumulation process in soil organisms. This study attempts to model elimination kinetics of organic chemicals in earthworms by accounting for the effects of both chemical and biological properties, including metabolism. The modeling approach that has been developed is based on the concept for simulating metabolism used in the BCF base-line model developed for predicting bioaccumulation in fish. Metabolism was explicitly accounted for by making use of the TIMES engine for simulation of metabolism and a set of principal transformations. Kinetic characteristics of transformations were estimated on the basis of observed kinetics data for the elimination of organic chemicals from earthworms.     

Continued development of a mass balance model of chemical fate in a sewage treatment plant

Chemicals that pass through a sewage treatment plant (STP) and into receiving waters lead to exposure of human and ecological receptors. Most countries require that such chemicals and especially those that are new to commerce be assessed for their treatability in STPs using a screening-level model. The STP model has been widely used for such assessments in Canada, the US and elsewhere. It is important for both industry and regulators that such a model be simple, accurate and applicable even with the limited data available for most chemicals. The STP model has been upgraded to include the capability to handle ionizing chemicals, and a variety of treatment plant configurations commonly used in Canada and elsewhere around the world. A scheme for obtaining appropriate biodegradation half-lives for the different treatment options from available aqueous biodegradation half-lives or standard biodegradability tests is suggested. Model simulations show good agreement with pilot-scale experimental data from literature for 20 organic chemicals with widely varying physico-chemical properties.