How to confirm identified toxicants in effect-directed analysis

Due to the production and use of a multitude of chemicals in modern society, waters, sediments, soils and biota may be contaminated with numerous known and unknown chemicals that may cause adverse effects on ecosystems and human health. Effect-directed analysis (EDA), combining biotesting, fractionation and chemical analysis, helps to identify hazardous compounds in complex environmental mixtures. Confirmation of tentatively identified toxicants will help to avoid artefacts and to establish reliable cause–effect relationships. A tiered approach to confirmation is suggested in the present paper. The first tier focuses on the analytical confirmation of tentatively identified structures. If straightforward confirmation with neat standards for GC–MS or LC–MS is not available, it is suggested that a lines-of-evidence approach is used that combines spectral library information with computer-based structure generation and prediction of retention behaviour in different chromatographic systems using quantitative structure–retention relationships (QSRR). In the second tier, the identified toxicants need to be confirmed as being the cause of the measured effects. Candidate components of toxic fractions may be selected based, for example, on structural alerts. Quantitative effect confirmation is based on joint effect models. Joint effect prediction on the basis of full concentration–response plots and careful selection of the appropriate model are suggested as a means to improve confirmation quality. Confirmation according to the Toxicity Identification Evaluation (TIE) concept of the US EPA and novel tools of hazard identification help to confirm the relevance of identified compounds to populations and communities under realistic exposure conditions. Promising tools include bioavailability-directed extraction and dosing techniques, biomarker approaches and the concept of pollution-induced community tolerance (PICT). Figure Toxicity confirmation in EDA as a tiered approach     

Mashup应用安全风险评估模型研究

Mashup应用作为企业情境应用程序,它利用从外部数据源检索到的内容来创建全新的服务.由于缺乏安全标准和核实鉴别的信任机制,随着更多的企业用户构建基于Mashup的应用,潜在的安全风险急剧增加.为了解决这个问题,以开发者的视角,通过解构Mashup应用的开发过程,集静态和动态安全风险因素于一体,透视Mashup应用的组...     

眼动指标在实时测量心理负荷中的应用进展

作业人员心理负荷大小关系着整个作业系统的安全,实时有效的测量监控作业人员心理负荷无疑会显著提高系统的可靠性。眼动指标作为一类重要的生理指标,因其实时性、无干扰性和有效性被广泛运用于心理负荷实时测量的研究中。将眼动指标分为注视指标、扫视指标、眨眼指标、瞳孔指标及其他指标五类分别进行阐述,介绍了国内外利用眼动指标测量心理负荷的研究现状,并对眼动指标在心理负荷测量领域的发展提出一些见解。     

公路隧道群运营安全性综合评价方法

在分析公路隧道群运营安全性综合评价特点和评价方法需求的基础上,提出基于集成云模型和物元分析理论的公路隧道群运营安全性综合评价方法,既能通过物元模型建立起评价对象与评价指标的对应关系,实现评价系统的信息反馈,又能通过云模型建立起概念数值表示与自然语言值描述之间的不确定性转换关系,从而实现语言值评价指标的不确定评估。最后,以西安—汉中高速公路隧道群区段为例进行工程实践应用分析。结果表明：该评价方法原理简单,可以对评价指标体系进行可拓变换,易于计算机编程研发公路隧道群运营安全性综合评价系统软件的工程推广应用。     

重庆市土地资源可持续利用综合评价

根据重庆市区域特点, 依据区域土地资源可持续利用的原理, 从经济的可行性、环境的保护性和社会的可接受性三大子系统共29个单项指标构建了重庆市土地资源可持续利用评价体系. 通过层次分析法确定了三大子系统和29个单项指标的权重, 对重庆市近7年的土地资源的可持续利用进行了定量分析. 并在分析重庆市土地资源可持续利用状况基础上, 对重庆市未来土地资源的可持续发展提出了可行性建议.     

新课程标准下初中化学教师应建立的教育理念

结合化学学科的特点,从课程观、学生观、学习观、教学观和评价观5个方面对新课程标准下初中化学教师应具有的教育理念进行了探讨,希望能对教师教育理念的转变有所帮助.     

Melt Quality Evaluation of Ductile Iron by Pattern Recognition of Thermal Analysis Cooling Curves

The melt quality of ductile iron can be related to the melt's thermal analysis cooling curve. The freezing zone of the thermal analysis cooling curve was found to indicate the melt quality of the ductile iron. A comprehensive difference parameter, Ω, of the thermal analysis cooling curves was found to be related to the properties of ductile iron melts such as composition, temperature, and graphite morphology. As Ω ap- proached O, the thermal analysis cooling curves were found to come together with all the properties indicat- ing melt quality about the same. A database of thermal analysis cooling curves related to the properties of the ductile iron melts was set up as a basis for a method to accurately evaluate the melt quality of ductile iron by pattern recognition of thermal analysis cooling curves. The quality of a ductile iron melt can then be immediately determined by comparing its thermal analysis cooling curve freezing zone shape to those in the database.     

围岩质量综合评判模型和大坝建基面优选模型的建立

阐述了岩体质量及其影响因素的复杂性和不确定性，采用模糊数学方法建立了考虑岩石单轴抗压强度，RQD，裂隙间隙，裂隙面粗糙度系数，裂隙水压力与最大应力比值的5因素洞室围岩综合评判模型，以及考虑岩体纵滤波速，完整性系数，变形模量，均一性系数，RQD，裂隙间距，承压水顶板岩体自重应力与承压水头比值的7在坝建基面模糊优选模型。     

基于地表水环境质量标准的富营养化评价方法

目前富营养化评价方法众多。但各评价方法之间缺乏可比性,不利于湖泊富营养化的有效管理和治理。在对现有湖泊富营养化的评价方法进行分析、评价的基础上,提出了适合我国国情的基于GB3838--2002《地表水环境质量标准》的湖泊畜营养化评价方法。该方法是将水质评价和主要富营养化因子评价相结合的综合的富营养化评价方法,在巢湖西半湖等合肥市湖、库富营养化评价中应用表明：该方法不仅可以对不同湖、库的富营养化状况进行比较,而且可以对同一湖泊富营养化的时空变化进行分析,有利于对湖泊富营养化程度做出客观、合理的判断,进一步探讨湖泊富营养化成因．为治理富营养化提供全面、科学的决策依据。     

火山岩气藏微观孔隙结构特征参数

针对火山岩气藏已成为中国石油重要的天然气勘探和开发的主要领域之一,利用恒速压汞技术研究了大庆徐深火山岩气藏岩芯的微观孔隙结构及其分布规律。研究表明:不同渗透率的低渗气藏岩心,其孔道半径基本相同,而喉道半径不同,对于所测得的不同渗透率的火山岩气藏岩芯来说,大约60%的喉道半径小于0.8μm。这与低渗透砂岩油藏岩芯的恒速压汞测试结果不同。平均喉道半径与渗透率有很好的相关关系。提出用平均喉道半径作为低渗气藏储层评价指标参数,来表征气体通过储层的难易程度。该研究成果对低渗气藏的分类评价和合理高效开发提供科学的决策依据