排序方式: 共有29条查询结果,搜索用时 15 毫秒
11.
Amin Jafari Jafar Heydari Abbas Keramati 《Environment, Development and Sustainability》2017,19(1):325-338
Modern societies face a dilemma called electronic waste (e-waste). This waste, which may contaminate the soil or cause unwanted impacts on human health when treated improperly, is one of the fastest growing waste streams in developed as well as developing countries and has brought great environmental impacts. Developing countries like Iran also face this modern waste management challenge. In order for more appropriate disposal or, if possible, recycling of this waste, more attention has been paid to reverse logistics as the most appropriate way to manage them. The first and most important action to address e-waste and implementation of reverse logistics is to persuade residents to bring back their obsolete electronic products. This paper attempts to understand significant factors affecting residents’ incentive dependency to participate in e-waste recycling program. Socioeconomic and demographic information of different residents is discussed by means of logistic regression for the first time in Iran. The results show that about 58.7 % of residents will participate even if no incentive is given. Household income, household size, education, e-waste concern level, and marital status are the significant factors affecting the incentive dependency of respondents. 相似文献
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Hamidreza Babaei Alireza Choobineh Hamidreza Pakshir Abdolreza Rajaeifard Jafar Rezaian 《International journal of occupational safety and ergonomics》2016,22(4):565-571
Introduction. Based on the literature, the ergonomic saddle chair provides the most appropriate posture for users. Determination of the seat height is critical to establish the proper posture, carried out using various methods of anthropometry. This study aimed to develop a simple and applied method for determining the saddle seat height with an emphasis on appropriate posture. Methods. In this study, anthropometric dimensions including weight, body height, popliteal height and seat height at 135° knee angle in 150 male and female dentists were measured. In the laboratory, to determine the ‘acetabuloischial number’, 25 male and female natural hip bones were measured. The mean saddle-chair height with knee angle of 135° was then compared by two different methods, field measurement and the new calculation method. Results. The results showed a strong correlation between data gathered from the two different methods, the field measurement and the new calculation method (98%), and Cronbach’s α from the intraclass correlation was equal to 0.994 (p?<?0.05). This indicated that the two methods produced similar results. Conclusion. The new method can be applied to calculate the optimal height of the saddle seat based on body height and popliteal height. 相似文献
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The aim of the current work is to provide information on how to improve the productivity and quality in the Horizontal Continuous Casting process (HCC). After a first numerical 2D/3D survey about the solidification in the HCC, an experimental investigation has been carried out to validate numerical results. Some casting parameters have been measured and collected: inlet and outlet temperatures, flow rate, heat flux and casting temperature. The study results lead to a correlation between these casting parameters and the casting quality. To obtain the best quality for each alloy, a set of operating parameters has been proposed. There is a very good agreement between the current results and earlier numerical results. Also based on the results, one can gain an insight on the productions of each casting machine and the grades of its quality. 相似文献
14.
Neghab M Norouzi MA Choobineh A Kardaniyan MR Zadeh JH 《International journal of occupational safety and ergonomics》2012,18(1):97-106
This study aimed to evaluate possible health effects associated with long-term occupational exposure to low levels of mercury vapors. Forty-six subjects exposed to mercury and 65 healthy unexposed employees were studied. The subjects were administered a questionnaire on experienced symptoms and underwent clinical examinations as well as routine biochemical tests. Atmospheric and urinary concentrations of mercury were measured, too. Environmental concentrations of mercury were estimated to be 3.97 ± 6.28 μg/m(3) and urinary concentrations of mercury in exposed and referent groups were 34.30 ± 26.77 and 10.15 ± 3.82 μg/dm(3), respectively. Additionally, symptoms such as somatic fatigue, anorexia, loss of memory, erethism, blurred vision and teeth problems were significantly more common among exposed individuals. These observations indicate that occupational exposure to mercury vapors, even at low levels, is likely to be associated with neurological and psychological symptoms. 相似文献
15.
The main purpose of this study was to ascertain whether occupational exposure to asphalt fumes, under normal working conditions, is associated with any hepatotoxic, nephrotoxic, or hematotoxic response. This was a cross-sectional study in which 210 subjects (80 exposed and 130 reference subjects) were investigated. Using standard methods, atmospheric concentrations of total particulate and benzene-soluble fractions of asphalt fumes were measured. Additionally, urine and blood samples were taken from subjects for complete blood count, white blood cell differential test, urinalysis, and routine biochemical tests of kidney and liver function. Both groups were similar as far as their demographic variables and smoking habits were concerned. The levels of exposure to total particulate and benzene-soluble fractions were estimated to be 0.9?±?0.2 and 0.32?±?0.09 mg m?3, respectively (mean?±?SD), both of which being lower than the existing threshold limit values. Statistically, significant associations between exposure to asphalt fumes and changes in most liver and kidney function tests and complete blood count parameters provided circumstantial evidence in favor of the notion that exposure to sub-threshold limit value levels of total particulate and benzene-soluble fractions is associated with early liver and kidney dysfunction as well as hematological disorders. 相似文献
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Jafar Mahmoudi 《International Journal of Green Energy》2013,10(1):25-41
This paper describes a methodology used for designing louvered fins. Louvered fins are commonly used in many compact heat exchangers to increase the surface area and initiate new boundary layer growth. Detailed measurements can be accomplished with computational models of these louvered fins to gain a better understanding of the flow field and heat distribution. The particular louver geometry studies for this work have a louver angle of 23° and fin count of 17 fpi. The flow and heat transfer characteristics for three-dimensional mixed convection flows in a radiator flat tube with louvered fins are analyzed numerically. A three-dimensional model is developed to investigate flow and conjugate heat transfer in the copper-based car radiator. The model was produced with the commercial program FLUENT. The theoretical model has been developed and validated by comparing the predictions of the model with available experimental data. The thermal performance and temperature distribution for the louvered fins were analyzed and a procedure for optimizing the geometrical design parameter is presented. One fin specification among the various flat tube exchangers is recommended by first considering the heat transfer and pressure drop. The effects of variation of coolant flow conditions and external air conditions on the flow and the thermal characteristics for the selected radiator are investigated also. The results will be used as fundamental data for tube design by suggesting specifications for car radiator tubes. 相似文献
18.
Caspian roach, Rutilus rutilus caspicus, might experience potassium permanganate (PM) toxicity, because it is common and widely used disinfectant in fish rearing and propagation centers in Iran. Thus, acute toxicity (24-h-LC50) of PM was determined on Caspian roach in two size classes (small and large groups), under aerated and non-aerated conditions, using static non-renewal system. 24-h-LC50 for PM in Caspian roach was 3.2, 3, 3.2, and 2.8?mg?L?1 in large-aerated, large-non-aerated, small-aerated, and small-non-aerated groups, respectively. Results indicated that aeration was led to decrease in PM toxicity, regardless of size class. However, large fish showed more tolerance to PM toxicity compared to small ones, under non-aerated condition. It is concluded that aeration could decrease the toxicity of PM that seems to be due to the increase in PM degradation, derived from increase in water turbulence. It is suggested that 96-h-LC50 may be more suitable to determine the effects of fish size on PM toxicity than 24-h-LC50. 相似文献
19.
Fatemeh Shaki Mir-Jamal Hosseini Jafar Shahraki Mahmoud Ghazi-Khansari 《毒物与环境化学》2013,95(7):1221-1234
Depleted uranium (DU) is widely used in military anti-armor weapons. Recent evidence suggested that oxidative stress and mitochondrial dysfunction may contribute to DU-induced toxicity. However, the underlying mechanisms of DU toxicity in mitochondria are not well understood. In this study, liver mitochondria were obtained from Wistar rats treated with DU in the form of uranyl acetate (UA) (0.5, 1 or 2 mg/kg i.p.) using differential centrifugation. For in vitro experiments, control rat liver mitochondria were incubated with different concentrations of UA (50, 100 or 200 μM) for 1 hr. Mitochondrial reactive oxygen species (ROS) production, collapse of mitochondrial membrane potential, and mitochondrial swelling were examined by flow cytometry. Mitochondrial sources of ROS formation were determined using specific substrates and inhibitors. Extent of lipid peroxidation (LPO) and glutathione (GSH) oxidation, and also complex II and IV activities were detected via spectroscopy. Further, the concentration of ATP and ATP/ADP ratio was measured using luciferase enzyme and release of cytochrome c from mitochondria which was detected by ELISA kit. UA induced succinate-supported mitochondrial ROS production, elevated LPO levels, GSH oxidation, and mitochondrial complex II inhibition. UA also induced mitochondrial permeability transition and increase in cytochrome c release which subsequently disturbed oxidative phosphorylation and reduced the mitochondrial ATP concentration. Data suggest that mitochondrial oxidative stress and uncoupling of oxidative phosphorylation may play key roles in DU-induced hepatic toxicity. 相似文献
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Effect of fertilizer application on soil heavy metal concentration 总被引:22,自引:0,他引:22
Zahra Atafar Alireza Mesdaghinia Jafar Nouri Mehdi Homaee Masoud Yunesian Mehdi Ahmadimoghaddam Amir Hossein Mahvi 《Environmental monitoring and assessment》2010,160(1-4):83-89
A large amount of chemicals is annually applied at the agricultural soils as fertilizers and pesticides. Such applications may result in the increase of heavy metals particularly Cd, Pb, and As. The objective of this study was to investigate the variability of chemical applications on Cd, Pb, and As concentrations of wheat-cultivated soils. Consequently, a study area was designed and was divided into four subareas (A, B, C, and D). The soil sampling was carried out in 40 points of cultivated durum wheat during the 2006–2007 periods. The samples were taken to the laboratory to measure their heavy metal concentration, soil texture, pH, electrical conductivity, cationic exchange capacity, organic matter, and carbonate contents. The result indicated that Cd, Pb, and As concentrations were increased in the cultivated soils due to fertilizer application. Although the statistical analysis indicates that these heavy metals increased significantly (P value < 0.05), the lead and arsenic concentrations were increased dramatically compared to Cd concentration. This can be related to overapplication of fertilizers as well as the pesticides that are used to replant plant pests, herbs, and rats. 相似文献