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121.
Exposure to perchlorate is widespread in the United States and many studies have attempted to character the perchlorate exposure by estimating the average daily intakes of perchlorate. These approaches provided population-based estimates, but did not provide individual-level exposure estimates. Until recently, exposure activity database such as CSFII, TDS and NHANES become available and provide opportunities to evaluate the individual-level exposure to chemical using exposure surveillance dataset. In this study, we use perchlorate as an example to investigate the usefulness of urinary biomarker data for predicting exposures at the individual level. Specifically, two analyses were conducted: (1) using data from a controlled human study to examine the ability of a physiologically based pharmacokinetic (PBPK) model to predict perchlorate concentrations in single-spot and cumulative urine samples; and (2) using biomarker data from a population-based study and a PBPK model to demonstrate the challenges in linking urinary biomarker concentrations to intake doses for individuals. Results showed that the modeling approach was able to characterize the distribution of biomarker concentrations at the population level, but predicting the exposure-biomarker relationship for individuals was much more difficult. The type of information needed to reduce the uncertainty in estimating intake doses, for individuals, based on biomarker measurements is discussed. 相似文献
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对现行采用的多种常用建设用地需求量预测方法进行了比较,并以苏州市为例,采用5种预测模型进行了对比分析,利用近13年的统计数据进行了验证.结果表明,广义加权组合预测法得到的结果误差最小、精度最高. 相似文献
124.
Performance and Environmental Impact of Biodegradable Films in Agriculture: A Field Study on Protected Cultivation 总被引:5,自引:1,他引:4
Anu Kapanen Evelia Schettini Giuliano Vox Merja Itävaara 《Journal of Polymers and the Environment》2008,16(2):109-122
The performance, the degradability in soil and the environmental impact of biodegradable starch-based soil mulching and low
tunnel films were assessed by means of field and laboratory tests. The lifetime of the biodegradable mulches was 9 months
and of the biodegradable low-tunnel films 6 months. The radiometric properties of the biodegradable films influenced positively
the microclimate: air temperature under the biodegradable low tunnel films was 2 °C higher than under the low density polyethylene
films, resulting in an up to 20% higher yield of strawberries. At the end of the cultivation period, the biodegradable mulches
were broken up and buried in the field soil together with the plant residues. One year after burial, less than 4% of the initial
weight of the biodegradable film was found in the soil. According to ecotoxicity tests, the kinetic luminescent bacteria test
with Vibrio fischeri and the Enchytraeus albidus ISO/CD 16387 reproduction potential, there was no evidence of ecotoxicity in the soil during the biodegradation process.
Furthermore, there was no change in the diversity of ammonia-oxidizing bacteria in the soil determined on the basis of the
appearance of amoA gene diversity in denaturing gradient gel electrophoresis. 相似文献
125.
对企业实施分级监察的基础是企业监察级别的确定。分级监察是以“风险优先”为基本的原则风险管理思想。本文在对我国现有的安全生产法规政策和安监部门的部分执法文书以及企业违法处罚情况进行分析总结的基础上,建立了企业违法处罚情况的量化模型,并以企业职业伤害风险和企业违法处罚结果为影响因素,建立了二元分级监察模型。运用所建立的模型对辽宁省某市的159家调研企业的监察级别进行了划分,并对分级结果进行了简要分析。 相似文献
126.
A.?K.?MohantyEmail author P.?Tummala W.?Liu M.?Misra P.?V.?Mulukutla L.?T.?Drzal 《Journal of Polymers and the Environment》2005,13(3):279-285
Biocomposites from soy based bioplastic and chopped industrial hemp fiber were fabricated using twin-screw extrusion and injection molding process. Soy based bioplastics were prepared through cooking with plasticizer and blending with biodegradable poly(ester amide). Mechanical, thermal properties and fracture surface morphology of the “green”/biocomposites were evaluated with universal testing system (UTS), dynamic mechanical analysis (DMA), Environmental Scanning Electron Microscopy (ESEM). It was found that the tensile strength and modulus, flexural strength and modulus, impact strength and heat deflection temperature of industrial hemp fiber reinforced biocomposites significantly improved. The fracture surfaces showed no signs of matrix on the fiber surface suggesting poor interfacial adhesion. 相似文献
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128.
ABSTRACT: Literatures on price‐based urban water conservation and on market‐based mechanisms to manage natural resources suggest that market‐based management of urban/suburban water use may be feasible. A market‐based proposal that emerged from a water shortage on California's Monterey Peninsula is presented. In the proposal, conservation incentives arise both from an ability among end‐users of water to reduce consumption and sell use‐rights to water, and from a penalty price for consumption in excess of one's use rights. The amount of water associated with use rights is capped and varies according to hydrological, meteorological, ecological, and other criteria. Requirements for further study of the proposal are listed, and the role that similar market‐based mechanisms could play in urban water management is discussed. 相似文献
129.
大型厂房消防安全设计评估 总被引:6,自引:4,他引:2
借鉴国际性能法规发展的经验,跟踪国际火灾科学研究前沿,着手研究和建立适用于我国新的建筑防火设计规范体系,已成为我国消防现代化建设的重要战略任务之一。作者以具体实例为对象,分别采用处方式和性能化设计方法进行建筑防火设计评估,演示两者设计过程和设计理论的差异。本文将是一组文章之一,针对一个大型边间厂房的具体设计按照处方式法规进行了评估,文章鉴别设计中不符合现行规范的条款并按规范提出修订方案,其阐述和讨论结果可为进一步进行火灾安全性能设计提供参考。有关的性能设计分析将在另一篇文章中详细介绍。 相似文献
130.
固定床PVC燃烧脱氯的机理和试验 总被引:14,自引:2,他引:12
研究垃圾组分PVC在焚烧过程中HCl的排放和脱除特性的实验在准等温、电加热的水平石英管反应器中进行.随着床温从700℃升高到900℃,HCl的转化率从82.5%平缓增加到88.3%,而过量空气系数的增加促使部分HCl转化为C12(1.9%~4.5%)的形式存在.钙基吸收剂CaCO3,Ca(OH)2,Ca(CH3COO)2对HCl的脱除效率高达68%~79%,而镁基吸收剂的脱氯效率却低于3%.小的吸收剂粒径、高的Ca/Cl比会促进脱氯效率的提高;烟气中CO2和H2O对脱氯效率的影响与它们在反应平衡中所起作用有关.高温下燃烧固氯机理反应的平衡常数的计算不仅诠释了实验结果,而且提供了脱氯吸收剂选择的依据. 相似文献