Effluent impact assessment using microarray-based analysis in common carp: a systems toxicology approach

Effluents are a main source of direct and continuous input of pollutants to the aquatic environment, and can cause ecotoxicological effects at different levels of biological organization. Since gene expression responses represent the primary interaction site between environmental contaminants and biota, they provide essential clues to understand how chemical exposure can affect organismal health. The aim of the present study was to investigate the applicability of a microarray approach for unraveling modes of action of whole effluent toxicity and impact assessment. A chronic toxicity test with common carp (Cyprinus carpio) was conducted where fish were exposed to a control and 100% effluent for 21 days under flow-through conditions. Microarray analysis revealed that effluent treatment mainly affected molecular pathways associated with the energy balance of the fish, including changes in carbohydrate and lipid metabolism, as well as digestive enzyme activity. These gene expression responses were in clear agreement with, and provided additional mechanistic information on various cellular and higher level effects observed for the same effluent. Our results demonstrate the benefit of toxicogenomic tools in a “systems toxicology” approach, involving the integration of adverse effects of chemicals and stressors across multiple levels of biological complexity.     

A numerical study of the auto-ignition temperatures of CH4–Air,C3H8–Air,CH4–C3H8–Air and CH4–CO2–Air mixtures

The auto-ignition temperature (AIT) is an important parameter in the process industries. In order to ensure a safe working environment in process industries, it is important to predict the AIT of combustible gases or vapors. In this study, the AITs of natural gas mixtures (CH₄–Air, C₃H₈–Air, CH₄–C₃H₈–Air and CH₄–CO₂–Air) are calculated based on a detailed kinetic model. To create a more practical model, different ignition criteria and convective heat transfer coefficients are investigated and compared against one another, resulting in the temperature criterion and a convective heat transfer coefficient of h = 50 W/(m² K). The results showed that the AITs of CH₄–Air and C₃H₈–Air decrease with an increase of equivalence ratios. While the propane ratio increasing, the AIT of CH₄–C₃H₈–Air decreasing. Reaction path analysis of natural gas mixtures (CH₄–C₃H₈) was also carried out to explain this phenomenon, yielding results showing that C₃H₈ is the main reaction during the ignition induction period. In addition the AIT of CH₄ increases slowly in positive correlation with CO_2, which plays a role of an inert gas. Comparing the results with literature work revealed a deviation of about 10%. Thus, it can be reasonably concluded that the AIT of a low hydrocarbons mixtures such as natural gas can be reliably predicted with detailed kinetic model.     

粉尘—空气混合物的最小爆炸浓度

对最小爆炸浓度估算的方法进行了评论，论述了对一些标准测试方法修改的必要性，以及引入新参数（如最小危险质量）的必要性。     

Chemical contamination and the ecological quality of surface water

In the assessment of the quality of surface waters, the typical procedure is that the concentration of contaminants in the surface water is monitored and subsequently compared with their respective Maximum Permissible Concentrations (MPCs). If the MPCs are not exceeded the water quality is considered to be safe. But can we be certain that this is true?We compared MPCs to observed and calculated effects of measured contaminants in Dutch surface waters and showed that effects of mixtures can cause a daphnid population to go extinct within 30 h of exposure even when MPCs are not exceeded. We conclude that there are shortcomings underlying the concepts of the MPCs. And that the MPCs aim to protect 95% of all species is not met.