This article describes an experimental program developed to investigate the potential for using hydrocarbon‐contaminated soils as a fine aggregate replacement in concrete. Five different contaminated soil types with a total petroleum hydrocarbon content of less than 1% were investigated. For each soil type, three concrete mixtures were obtained by replacing sand with contaminated soils (10, 20, and 40% replacement ratio). The resulting concrete was tested for setting times, compression strength, flexural strength, durability, and teachability of benzene to water.
The results indicate that the addition of hydrocarbon‐contaminated soil adversely affects the strength of concrete. The strength reduction at each soil replacement level depends on contamination concentration, contaminant type, and soil type. The durability of the tested concrete is comparable to normal concrete. For all five soils at a 40% replacement ratio, the leachability of benzene was nondetectable after 24 h and after 10 d. After testing the leachability of artificially contaminated soils (0.5 and 3% neat benzene contamination) for 24 h, it was found that the leaching of benzene increases with the percentage of contamination. However, the fraction of benzene that leached was about 95% lower than the values for loose soils. 相似文献
With healthcare systems under pressure from scarcity of resources and ever-increasing demand for services, difficult priority setting choices need to be made. At the same time, increased attention to patient involvement in a wide range of settings has given rise to the idea that those who are eventually affected by priority setting decisions should have a say in those decisions. In this paper, we investigate arguments for the inclusion of patient representatives in priority setting bodies at the policy level. We find that the standard justifications for patient representation, such as to achieve patient-relevant decisions, empowerment of patients, securing legitimacy of decisions, and the analogy with democracy, all fall short of supporting patient representation in this context. We conclude by briefly outlining an alternative proposal for patient participation that involves patient consultants. 相似文献
Along with progress in globalization of society, the spread of infectious diseases has accelerated worldwide. The deployment of highly sensitive genetic tests is essential for early diagnosis and early containment of potential outbreaks and epidemics, as well as routine surveillance, although tedious and expensive nucleic acid extraction steps represent a major drawback. Here we developed a simple and rapid DNA extraction method, named as an EZ-Fast kit, applicable to the field setting. The kit does not require advanced laboratory equipment or expensive DNA extraction kits and achieves crude DNA extraction within 10 min at extremely low cost and can easily be performed in field settings. When combined with real-time PCR and LAMP analyses, the performance of the POCT, using 183 bovine blood samples, was similar to that of the existing DNA extraction method: 92·5% (135/146) (real-time PCR) and 93·7% (133/142) (LAMP) diagnostic sensitivities, and 100% diagnostic specificities. The developed POCT provides a powerful tool to facilitate on-site diagnosis in a field setting. 相似文献
The current standard for pesticides in groundwater in the Netherlands is the same as that for drinking water: a maximum of 0.1 μg per liter for each individual pesticide and a maximum of 0.5 μg per liter for all agents collectively. This standard applies to water located at least ten meters below ground level. It is based on an old detection limit, which is out of date by now, and on the view that drinking water should be entirely free of pesticides. Recently, however, there are increasing calls for a system of standards underpinned by toxicological data. A committee of the Health Council of the Netherlands (please see note at the end of this article) has dealt with the question whether, apart from human health criteria, ecotoxicological criteria should be taken into consideration when evaluating the risks posed by pesticides in groundwater. This paper closely follows the executive summary of her report 相似文献
The National Pollutant Release Inventory (NPRI) provides pollutant release and transfer data from point sources to various media in the Canadian environment. While the inventory serves as Canada's community right-to-know program, the growing number of listed substances and reporting facilities makes it exceedingly difficult for the public to discern which substances are of greatest concern in their respective communities. A chemical's impact is best characterized when its environmental release data are combined with its toxicity and environmental fate properties. Presently, the NPRI does not provide a synthesis of this critical information and there is a need to provide more context with NPRI data to increase its usability. To help deliver this context, a relative risk ranking was compiled for a subset of NPRI substances using a modified Chemical Hazard and Evaluation Management Strategies (CHEMS-1) model. The model combines toxicity, chemical fate properties, and NPRI release data to yield a risk score for each substance. The resulting risk scores are ranked accordingly to provide a priority ranking of the substances. In addition to contextualizing the NPRI release data with hazard information, the ranking can also help set priorities for future risk assessment and evaluation by the Canadian government and scientific community. Limitations included the reliance on modelled data and default values to fill data gaps and uncertain reliability in reported NPRI data. In spite of its limitations, the CHEMS-1 model is a useful tool for prioritizing NPRI substances. 相似文献
Summary Tetraploidy was induced in outbred pearl millet and selection for high and low seed set was started in the C1 generation. Segregation in the C3 generation was observed for fertility and also for meiotic features: per cent seed set in selfed earhead, chiasma frequency, chromosome association and chromosome distribution in pollen mother cells were all affected. However, variation in seed set was observed even between samples not differing in meiotic features. It is apparent that factors regulating seed set in autotetraploid pearl millet were genic as well as chromosomal.A high frequency of univalents and trivalents was the main cause of sterility; quadrivalent misdisjunction was not a significant factor. As univalency decreased with increased chiasma formation, the gain was in the form of quadrivalents. However, individuals not differing in chiasma frequency did differ in chromosome association frequencies, indicating that the dependence of chromosome pairing behaviour on chiasmata was subject to genotypic influence. 相似文献