Comparison of six correlative models in predictive vegetation mapping on a local scale

A variety of statistical techniques has been used in predictive vegetation modelling (PVM) that attempt to predict occurrence of a given community or species in respect to environmental conditions. We compared the performance of three profile models, BIOCLIM, GARP and MAXENT with three nonparametric models of group discrimination techniques, MARS, NPMR and LRT. The two latter models are relatively new statistical techniques that have just entered the field of PVM. We ran all models on a local scale for a given grassland community (Teucrio-Seslerietum) using the same input data to examine their performance. Model accuracy was evaluated both by Cohen’s kappa statistics (κ) and by area under receiver operating characteristics curve based both on resubstitution of training data and on an independent test data set. MAXENT of profile models and MARS of group discrimination techniques achieved the best prediction.     

Effect of some xenobiotics on kynurenine hydrolase and kynurenine aminotransferase of mouse liver

The effects of some xenobiotics on the activity of the B6-dependent kynurenine hydrolase (KH) and kynurenine aminotransferase (KATE) in mouse liver, were investigated. Polychlorinated biphenyl (Aroclor 1254) (400mg/kg/day x4) markedly decreased the activity of both enzymes. Benzo(a)pyrene (BP) and 3-methylcholanthrene (3-MC) (40mg/Kg/day x1) as well as phenobarbital (PB) (75mg/kg/day x3) did not alter the activity of KH, while that of KATE was mildy reduced. The response of the two enzymes to treatment with chlorpromazine (CPZ) (5mg/Kg/day x5) were opposite with marked elevation of KH and inhibition of KATE activities. Treatment with B-naphthoflavone (B-NF) (80mg/Kg/day x2), Pyrazole (200mg/Kg/day x1) or indole (400mg/kg/day x1) produce no change in the activity of either enzyme. It, seems therefore, that Aroclor (1254) and chlorpromazine may cause disordered kynurenine metabolism through alterations in the activities of its metabolizing enzymes. This, in turn, might affect nicotinamide adenine dinucleotide biosynthesis and/or the accumulation of some tryptophan metabolites suspected of being carcinogenic or co-carcinogenic.     

Musculoskeletal symptoms as related to ergonomic factors in Iranian hand-woven carpet industry and general guidelines for workstation design.

Carpet weaving is a high risk occupation for developing musculoskeletal disorders (MSDs). The objectives of the present study, which was carried out in the Iranian hand-woven carpet industry, were determination of the prevalence of MSD symptoms, identification of major factors associated with MSD symptoms and development of guidelines for workstation design. 1,439 randomly selected weavers participated in this study. A questionnaire was used to collect data on MSD symptoms. The results revealed that the prevalence rates for symptoms in different body regions were high as compared to the general Iranian population (for neck, back and large joints, p <.0001). The results of multivariate analyses showed that major ergonomic factors associated with musculoskeletal symptoms were loom type, working posture, daily working time and seat type. Based on the results, some general guidelines for designing weaving workstations were developed. A prototype test showed that the new workstation was acceptable for subject tests and that it improved working posture.     

Radioactivities related to coal mining

Natural radioactivity concentrations due to the coal mining in Gabal El-Maghara, North Sinai, Egypt, were determined using gamma-ray spectroscopy. Coal, water and soil samples were investigated in this study. The (226)Ra, (232)Th and (40)K activity concentrations in coal before extraction were 18.5 +/- 0.5, 29.5 +/- 1.2 and 149.0 +/- 8.4 Bq kg(-1), respectively. These concentrations were reduced to 18-22% after extraction due to the clay removal of the coal ore. The activity contents of the water and soil samples collected from the surrounding area did not show any evidence of enhancement due to the mining activities. Absorbed dose rate and effective dose equivalent in the mine environment were 29.4 nGy h(-1) and 128.0 microSv a(-1), respectively. The measured activity concentrations in the mine environment and the surrounding areas (5 km away from the mine) are similar to that found in other regions in North and South Sinai. Based on the measurements of gamma-ray emitting radionuclides, the mine activity does not lead to any enhancement in the local area nor represents any human risk.     

Waste high impact polystyrene (HIPS) microfiltration membranes for water treatment: A thorough experimental study

In our previous work, the prepared high-impact polystyrene (HIPS) membranes, synthesized using four concentrations (20, 25, 30, and 35 wt%) of waste HIPS, were proved to be promising for water purification by microfiltration process (MF). However, the fabricated membranes' mechanical properties and microfiltration process parameters were not investigated. Consequently, in this study, various parameters affecting the previously fabricated membranes' performance in the filtration process, such as membrane mechanical properties, feeding pressure, fouling behavior, and polymer concentration, were thoroughly investigated. With increasing polystyrene concentrations, the ultimate tensile strength of the fabricated membranes increased. When the concentration was increased from 20 to 25 wt percent, the elongation at break rose, but as the concentration was increased further, the membrane became brittle. Permeate flux and rejection both declined as polymer content was raised. Accordingly, the highest flux and humic acid (HA) rejection were shown by 20 wt% (14.18 L/m²h (LMH) and 98.95%, respectively). The antifouling properties declined when the polymer concentration was raised, and 20 wt% had the lowest total fouling resistance. Furthermore, the permeate flux was reduced while increasing the HA initial concentration.     

Blade thickness effect on the aerodynamic performance of an asymmetric NACA six series blade vertical axis wind turbine in low wind speed

ABSTRACT

Vertical axis wind turbine (VAWT) is an economic and widely used energy converter for converting wind energy into useful form of energy, like mechanical and electrical energy. For efficient energy conversion in low wind speed and to have improved power coefficient of asymmetric blade VAWT, selection of optimum blade thickness is needed thus entailing its detailed investigation with respect to different operating wind speed conditions. Present study methodically explores the impact of thickness to chord (t/c) ratio on aerodynamic performance of a three bladed asymmetrical blade H-Darrieus VAWT at different low wind speed conditions by using 2D unsteady CFD simulations. The optimal t/c is obtained on the basis of maximum power coefficient and average moment coefficient of the turbine. The aerodynamic performance curves are obtained at different operating and t/c conditions and the performance insights are corroborated with the findings from the flow physics study to come to some concrete conclusions on the effects of the thickness to chord ratio. The present study identifies large blade curvature to create a large diverging passage on the blade suction surface as the prominent reason for aerodynamic performance drop at a high t/c ratio.     

Biosurfactant electrospun nanofibers exhibit minimal side effects on the structure and function of the liver tissue in male rat model

Environmental Science and Pollution Research - Oil spills can result in significant damage to marine estuaries, rivers, lakes, wetlands, and shorelines. Electrospun nanofibers containing...     

A new trend in the medication of hepatocyte cytoxicity in mice: protective role of probiotic bacteria

Environmental Science and Pollution Research - Liver toxicity is affected by several factors, including certain medications, fumes emission from factories, materials used in industries, and...     

Assessment of a heat pipe solar collector with nanofluids

Environmental Science and Pollution Research - This research was designed to experimentally study the influence of using three metal oxide nanofluids at different high flow rates with various mass...