Chronic Health Risks from Aggregate Exposures to Ionizing Radiation and Chemicals: Scientific Basis for an Assessment Framework

Very little quantitative analysis is currently available on the cumulative effects of exposure to multiple hazardous agents that have either similar or different mechanisms of action. Over the past several years, efforts have been made to develop the methodologies for risk assessment of chemical mixtures, but mixed exposures to two or more dissimilar agents such as radiation and one or more chemical agents have not yet been addressed in any substantive way. This article reviews the current understanding of the health risks arising from mixed exposures to ionizing radiation and specific chemicals. Specifically discussed is how mixed radiation/chemical exposures, when evaluated in aggregation, were linked to chronic health endpoints such as cancer and intermediate health outcomes such as chromosomal aberrations. Also considered is the extent to which the current practices are consistent with the scientific understanding of the health risks associated with mixed-agent exposures. From this the discussion moves to the research needs for assessing the cumulative health risks from aggregate exposures to ionizing radiation and chemicals. The evaluation indicates that essentially no guidance has been provided for conducting risk assessment for two agents with different mechanisms of action (i.e., energy deposition from ionizing radiation versus DNA interactions with chemicals) but similar biological endpoints (i.e., chromosomal aberrations, mutations, and cancer). The literature review also reveals the problems caused by the absence of both the basic science and an appropriate evaluation framework for the combined effects of mixed-agent exposures. This makes it difficult to determine whether there is truly no interaction or somehow the interaction is masked by the scale of effect observation or inappropriate dose-response assumptions.     

锌在PAN修饰的铅笔芯电极上的差分脉冲阳极溶出伏安特性

用1-(2-吡啶偶氮)-2-萘酚(PAN)修饰铅笔芯电极研究锌的差分脉冲阳极溶出伏安特性。测得锌在 PAN 修饰的铅笔芯电极(PCPE)上,于—0.92V 处有良好的溶出峰。峰电流 i_p 与锌离子浓度在4.0×10~(-7)～4.0×10~(-5)mol·L~(-1)范围内呈良好的线性关系。用以测定植物中的微量锌,与原子吸收法测定结果基本一致。并初步探讨了该修饰电极对锌的富集和溶出机理。     

化学教学中的发散思维及其培养

理论联系实际地阐述了发散思维的原理与方法,说明了在化学教学中培养学生的发散思维对于增强学生能力、提高学生素质的重要意义。     

关于化学实验课程体系建设的思考

分析了我校非化学专业化学实验课的现状与不足,指出化学实验教学应该把学生基本实验技能和综合实验能力的培养放在首位,并在此基础上构建了新的化学实验课程体系。新课程体系破除二级学科界限,注重基本实验技能和综合实践能力的培养。灵活运用多种教学方法是提高实验教学水平的重要保证。     

商品化率对化肥用量的影响拐点及其减量政策含义

基于资本要素禀赋理论,构建农产品商品化率影响农户化肥施用量的理论模型,以阐明商品化率对化肥用量的影响机理,并结合湖北省江汉平原水稻种植户的调查数据进行实证检验。研究发现：（1）农产品商品化率对农户化肥施用量的影响具有拐点效应,二者呈现“倒U”型变动特征,转折的临界点为69.15%;(2)稻谷商品化率低于69.15%时,土地细碎化和劳动力非农转移对化肥用量具有显著的正向影响,表明土地均分制造成的土地细碎问题和家庭经营重心转向非农活动是引发低商品化率农户短期行为的诱因所在;（3）稻谷商品化率高于69.15%时,服务外包和土地经营规模对化肥用量具有显著负向影响,表明参与农业分工和开展农地规模经营能够激发高商品化率农户的长期行为。基于稻谷商品化率拐点前后的减量影响差异,认为低商品化率农户是化肥减量需要重点关注的群体,引导其减量的策略在于通过高标准农田建设解决土地细碎化问题,同时为机械化等节约人工的作业破除障碍;高商品化率农户的减量策略则在于鼓励有经营能力的农户扩大经营规模,支持有交易能力的农户参与农业分工。     

Handling uncertain decisions in whole process design

In recent years, the chemical and pharmaceutical industries have observed a noticeable decline in economic activity. This has resulted in many companies focusing on innovative research and development as they consider this key to business success. In particular, a number of leading industrial organisations have adopted the principles of Whole Process Design (WPD). WPD considers the optimisation of the entire product development process, from raw materials to end product, rather than focusing on each individual unit operation. The complexity involved with the implementation of WPD requires rationalised decision-making, often with limited or uncertain information. This paper presents the outcomes of two questionnaires that examined the requirements of professionals working within the chemistry-using industries with respect to developing a decision-making support tool. From the findings a methodology is proposed, the outcome of which allows a decision-maker to visually interpret their decision results with associated levels of uncertainty. A chemical route selection case study demonstrates and validates the application of the proposed methodology.     

The Architecture of Chemical Alternatives Assessment

Chemical alternatives assessment is a method rapidly developing for use by businesses, governments, and nongovernment organizations seeking to substitute chemicals of concern in production processes and products. Chemical alternatives assessment is defined as a process for identifying, comparing, and selecting safer alternatives to chemicals of concern (including those in materials, processes, or technologies) on the basis of their hazards, performance, and economic viability. The process is intended to provide guidance for assuring that chemicals of concern are replaced with safer alternatives that are not likely to be later regretted. Conceptually, the assessment methods are developed from a set of three foundational pillars and five common principles. Based on a number of emerging alternatives assessment initiatives, in this commentary, we outline a chemical alternatives assessment blueprint structured around three broad steps: Scope, Assessment, and Selection and Implementation. Specific tasks and tools are identified for each of these three steps. While it is recognized that on‐going practice will further refine and develop the method and tools, it is important that the structure of the assessment process remain flexible, adaptive, and focused on the substitution of chemicals of concern with safer alternatives.     

高校化学实验室对环境的污染及其治理

高校化学实验室排放的大量液体、气体、固体废弃物对环境污染严重。认识不到位,投资不足是其产生的主要原因。加强实验室管理,大力推广微型化学实验,推广连续合成实验和回收再利用,分类收集,区别处理是解决问题的主要途径。     

大力发展石油化工产业，振兴东北老工业基地

在振兴东北老工业基地的战略中,作为东北三省之一的吉林省,石油化工产业为其第二大支柱产业,其经济贡献无可替代.通过论述石油化工产业在吉林省的举足轻重的地位、未来发展的前景、目前存在的问题,指出在各种挑战之下我省石油化工产业应采取的应对措施.     

大学生毕业设计(论文)实践教学中若干意识的培养——以化工与制药类专业为例

以化工与制药类专业为例,探讨了毕业设计(论文)实践教学中大学生情报意识、安全意识、工程意识、创新意识、管理意识、环境保护意识和合作意识的教育问题.