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11.
The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.  相似文献   
12.
Contact flocculation-filtration of humic dispersions with alum in medium grain (0.62 mm) sand gave short runs to breakthrough, while in coarse (1.2 mm) media clarification was inefficient. Alum with cationic polymer gave in coarse media acceptable runs, but shorter then for mineral dispersions. Analysis of results by parameters of existing filtration models showed that using the Ives-Iwasaki model and plotting filtration coefficient λ vs specific deposit σ gave different λmax for different polymer dose, plot of λmax vs dose goes through maximum at optimum dose.Plotting the cube root of headloss vs square root of specific deposit gave a straight line corresponding to Shektman formula.Analysis by Adin-Rebhun model showed that for contact flocculation-filtration humic dispersions attachment coefficient k1 was similar to, detachment k2 was many fold higher then and theoretical maximum mass capacity much lower then in case of mineral dispersions.Calculations showed that the solid content and the density of alumo-organic deposits in bed are much lower than of alumo-mineral deposits. Polymers and minerals increase the solid content, the density of deposits and the mass capacity of filter beds.  相似文献   
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14.
Rambow  D.  Struckmeier  W. 《Grundwasser》2002,7(2):125-126
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15.
Many chemicals released into the environment without toxicological risks have the capacities to disrupt the function of endocrine systems. These endocrine disruptors disturb normal endocrine mechanisms and have been observed in nearly all classes of vertebrates. The aim of this research is to develop a comprehensive model to study endocrine disruption using the amphibian Xenopus laevis. The assessment of estrogenic potencies of endocrine disruptors includes several levels of investigation: (I) binding to liver estrogen receptor, (II) estrogenic activity in vitro by inducing vitellogenin synthesis in primary cultured hepatocytes, and (III) in vivo effects on sexual development caused by exposure of larvae. The present paper is focused on the first part by establishing a radioreceptorassay for [3H]17 beta-estradiol ([3H]E2) binding using liver cytosol fraction. In order to get optimum binding conditions we performed kinetic, saturation, and competitive displacement experiments. Association of [3H]E2 to estrogen receptor revealed that maximum specific binding is achieved between 18 and 48 h of incubation. Scatchard analyses of saturation experiments resulted in a homogenous saturable population of estrogen receptors having no significant differences of binding parameters between both sexes. The values of Kd (dissociation constant) in males and females were 22.4 +/- 6.0 and 15.0 +/- 2.8 nM (mean +/- S.E.M.; n = 5), respectively, while corresponding Bmax (maximum binding capacity) revealed 89 +/- 46 and 136 +/- 46 fmol [3H]E2/mg protein. The specificity of estrogen receptors as shown by competitive displacement experiments demonstrated receptors being highly specific just for estrogens, but not for other endogenous steroids having the following ranking of binding affinities: E2 > estrone > dehydroepiandrosterone > aldosterone > or = testosterone > or = corticosterone > or = progesterone. The affinity ranking of environmental chemicals compared to E2 was: E2 > tetrachlorbiphenyl > diethylphthalate > 2,2-bis-(4-hydroxyphenyl)-propan (bisphenol A) > or = 4-nonylphenol > or = 3-t-butyl-4-hydroxyanisole > or = 4-octylphenol > dichlor-diphenyl-trichlor-ethan (4,4'-DDT). Analyses of five sewage effluents for displacement of [3H]E2 binding resulted in three samples displacing more than 50% of specific binding at their original concentration. Taken together the established radioreceptorassay for [3H]E2 binding in Xenopus laevis liver cytosol is useful to screen estrogen receptor binding of pure compounds or complex mixtures of them, which is the prerequisite for causing either estrogenic or antiestrogenic effects.  相似文献   
16.
In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity. Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants. Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size). Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR. Giardia and Cryptosporidium were detected by conventional staining methods and PCR. The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs. The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake. Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced. Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L. Virus count was reduced in sand of filters after washing. Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%). Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%). At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing. Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium. It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).  相似文献   
17.
Synthesis of ettringite from acid wastewaters of the aluminium anodising industry has been studied as a possible route of reducing the emissions to the environment, recovering at the same time resource materials as a useful marketable mineral. Wastewaters of different concentrations have been subjected to the process of synthesis suspending calcium oxide and calcium aluminate powders at different time and pH conditions. High caustic alkalinity (pH approximately 12) and low sulphate concentrations (<0.1 M) are the most suitable conditions to synthesise ettringite. The mineral characterisation has been performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA), proving the high purity of the pursued solid product when hydrated in the appropriate sodium hydroxide concentrations. In such conditions, around 90% of the aluminium initially present in the wastewater solutions is recovered in the form of ettringite.  相似文献   
18.
W.P. Barber  PhD  DIC  BEng  CEng  MIChemE   《Water and Environment Journal》2005,19(3):214-224
A model was developed and tested to investigate the effects of various parameters on the processing costs of anaerobic digestion. The model was based on empirical data collected from full-scale plants which varied in size from 35,000 to 900,000 population equivalents. (Equivalent to loading rates of 0.5 to 2.7 kg VS/m3/d.) In spite of different operating regimes and conditions of the plants analysed, various relationships were discovered between: sludge quality and volatile solids destruction; sludge quality and biogas yield; and, effluent volatile solids and dewatering. Where correlations existed, these were used to make predictions on operating costs of the digestion and dewatering plant based on sensitivity analysis. The results of the model were used to make recommendations on how to optimise the operation of an anaerobic digestion plant.  相似文献   
19.
Finite element modelling of plate girders with web openings   总被引:1,自引:0,他引:1  
This paper is concerned with a finite element model to predict the behaviour and ultimate load of plate girders with web openings. The finite element package is used to model the plate girders with web openings. Accuracy of the model is assessed by applying it to plate girders tested earlier by other researchers. Comparison of analytical results with the available experimental results for yielding patterns, ultimate load values and load–deflection relationships show good agreement between the finite element and experimental results thus validating the accuracy of the proposed model. The proposed finite element method was extended to carry out a parametric study. The study covered parameters such as web slenderness and flange stiffness.  相似文献   
20.
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