The interactions of Cr (VI) concentrations and amendments (biochar and manure) on growth and metal accumulation of two species of Salicornia in contaminated soil

Environmental Science and Pollution Research - Heavy metals are among the most dangerous contaminants in the environment. Organic components and plant species that can accumulate and stabilize...     

Effects of cimetidine and N-acetylcysteine on paraquat-induced acute lung injury in rats: a preliminary study

Abstract

Lung injury in rats challenged with paraquat at 20?mg kg^?1 body weight was histopathologically evident by inflammation, hemorrhage, and vascular congestion. Increased levels of reactive oxygen species and lipid peroxidation, decreased glutathione content, and lower tissue antioxidant capacity was found. The effects of N-acetylcysteine and cimetidine, a well-known potent inhibitor for organic cation transport, were examined. Lung injury was attenuated by N-acetylcysteine but not by cimetidine. The findings are consistent with the assumption that beneficial effects of N-acetylcysteine administration in paraquat-challenged animals might be linked to its ability for preserving the cellular redox environment and preventing oxidative stress, while cimetidine might even hasten paraquat-induced lung injury. On the other hand, the effects of cimetidine on paraquat-induced lung injury underline the importance of future studies on the role of transporters in this complication.     

Upper trapezius fatigue in carpet weaving: the impact of a repetitive task cycle

Introduction. Shoulder disorders are one of the most prevalent musculoskeletal disorders among carpet weavers. The most important cause of these disorders is muscle fatigue. The aim of the present study is to investigate the effect of carpet weaving characteristics on upper trapezius (UTr) muscle fatigue during a task cycle. Method. In this cross-sectional study, 9 women and 3 men participated. During an 80-min cycle of carpet weaving, a times-series model was applied to assess electromyography amplitude and frequency changes. Result. According to the joint analysis of electromyogram spectrum and amplitude method, the participants experienced 0% force decrease, 0.9% recovery, 18% force increase and 72% fatigue in the left UTr. Furthermore, the rates of force decrease, recovery, force increase and fatigue in the right UTr were 18%, 18%, 18% and 45%, respectively. Fatigue in the right and the left UTr was reported to be the dominant state during one carpet weaving task cycle. Conclusion. Task cycle appears to have a significant impact on UTr fatigue in participants, and UTr fatigue can be considered a serious risk factor in shoulder musculoskeletal disorders. Hence, further studies should focus on better workstations and work–rest periods during various subtasks.     

A HYBRID OPTIMIZATION APPROACH TO THE ESTIMATION OF DISTRIBUTED PARAMETERS IN TWO-DIMENSIONAL CONFINED AQUIFERS1

ABSTRACT: In using non-linear optimization techniques for estimation of parameters in a distributed ground water model, the initial values of the parameters and prior information about them play important roles. In this paper, the genetic algorithm (GA) is combined with the truncated-Newton search technique to estimate groundwater parameters for a confined steady-state ground water model. Use of prior information about the parameters is shown to be important in estimating correct or near-correct values of parameters on a regional scale. The amount of prior information needed for an accurate solution is estimated by evaluation of the sensitivity of the performance function to the parameters. For the example presented here, it is experimentally demonstrated that only one piece of prior information of the least sensitive parameter is sufficient to arrive at the global or near-global optimum solution. For hydraulic head data with measurement errors, the error in the estimation of parameters increases as the standard deviation of the errors increases. Results from our experiments show that, in general, the accuracy of the estimated parameters depends on the level of noise in the hydraulic head data and the initial values used in the truncated-Newton search technique.     

OPTIMAL ESTIMATION OF CONTAMINANT TRANSPORT IN GROUND WATER1

ABSTRACT: Finite element and finite difference representations of the convective-dispersive equation have been widely used in determining contaminant transport in ground water. Due to inherent uncertainties of the transport process, those representations are inexact and contain errors. Errors in field measurements are unavoidable. By combining a numerical model, a measurement equation, and the Kalman filter, optimal estimates of the state variable (contaminant concentration) can be obtained. This paper describes the algorithm and gives a numerical example of contaminant transport in a two-dimensional ground water flow. The results show significant improvement in the estimated concentration distribution by using the filtering technique.     

VELOCITY CONTROL AS A TOOL FOR OPTIMAL PLUME CONTAINMENT IN THE EQUUS BEDS AQUIFER,KANSAS1

ABSTRACT: A ground-water-management model was developed to investigate the best management options for the containment of an oil-field-brine plume in the Equus Beds aquifer in south-central Kansas. The main purpose of the management model was to find the optimal locations and minimum rates of pumpage of a set of plume-interception wells, to successfully reverse the velocity vectors at observation wells located along the plume front, and also to satisfy freshwater demands from supply wells. The effects of the calculated minimum withdrawals from the interception wells on the migration of contaminants throughout the ground-water system were evaluated utilizing a solute-transport model. This latter analysis was carried out to ensure the containment of the plume. Whereas application of the management model to the study area achieves the management objectives, the implementation of the results is believed to be impractical and expensive. This is because a considerable amount of water must be pumped out to reverse the velocity vectors in the vicinity of the plume. In general, the proposed technique of pollutant containment may be effective when applied to aquifers having low hydraulic gradients and/or to aquifers with hazardous plumes whose containment is not subject to economic constraints.     

地下水可溶性污染物迁移的最优估算

对流扩散方程的有限元和有限差方法已经广泛地用来模拟地下水污染物的迁移。由于迁移过程固有的不确定性,模拟方法的不准确性等都会给模型计算带来偏差;另外野外测量的误差也是不可避免的。通过数值模型、量测方程和卡尔曼滤波的结合,作为状态变量的污染物浓度可以优化给出。本文以二维地下水污染物的对流扩散方程为例,应用有限元方法导出卡尔曼滤波的转移矩阵,结果表明,使用滤波技术来估算地下水可溶性污染物浓度的分布比单独使用有限元方法有较大的优越性。     

Toxic responses of different organs following occupational exposure to sub-threshold limit value levels of paving asphalt fumes

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.     

Simultaneous monitoring of SARS-CoV-2, bacteria,and fungi in indoor air of hospital: a study on Hajar Hospital in Shahrekord,Iran

The novel SARS-CoV-2 outbreak was declared as pandemic by the World Health Organization (WHO) on March 11, 2020. Understanding the airborne route of SARS-CoV-2 transmission is essential for infection prevention and control. In this study, a total of 107 indoor air samples (45 SARS-CoV-2, 62 bacteria, and fungi) were collected from different wards of the Hajar Hospital in Shahrekord, Iran. Simultaneously, bacterial and fungal samples were also collected from the ambient air of hospital yard. Overall, 6 positive air samples were detected in the infectious 1 and infectious 2 wards, intensive care unit (ICU), computed tomography (CT) scan, respiratory patients’ clinic, and personal protective equipment (PPE) room. Also, airborne bacteria and fungi were simultaneously detected in the various wards of the hospital with concentrations ranging from 14 to 106 CFU m^?3 and 18 to 141 CFU m^?3, respectively. The highest mean concentrations of bacteria and fungi were observed in respiratory patients’ clinics and ICU wards, respectively. Significant correlation (p < 0.05) was found between airborne bacterial concentration and the presence of SARS-CoV-2, while no significant correlation was found between fungi concentration and the virus presence. This study provided an additional evidence about the presence of SARS-CoV-2 in the indoor air of a hospital that admitted COVID-19 patients. Moreover, it was revealed that the monitoring of microbial quality of indoor air in such hospitals is very important, especially during the COVID-19 pandemic, for controlling the nosocomial infections.