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In vitro toxicity of perfluorooctane sulfonate on rat liver hepatocytes: probability of distructive binding to CYP 2E1 and involvement of cellular proteolysis Texto completo
2017
Khansari, Mehdi Rajabnia | Yousefsani, Bahareh Sadat | Kobarfard, Farzad | Faizi, Mehrdad | Pourahmad, Jalal
Perfluorooctanesulfonate (PFOS), an anthropogenic fluorosurfactant, is one of the most common global pollutants. PFOS is used in various consumer products to provide soil, oil, and water resistance to materials used in clothing, upholstery, and food packaging. PFOS is persistent, bioaccumulative, and toxic to mammalian species. In this study, the cellular mechanisms involved in PFOS hepatotoxicity were evaluated. For this purpose, we determined oxidative stress markers including cell lysis, ROS generation, lipid peroxidation, glutathione depletion, mitochondrial membrane potential decrease, lysosomal membrane leakiness, and cellular proteolysis. Our results demonstrated that PFOS liver cytotoxicity was associated with reactive oxygen species (ROS) formation and lipid peroxidation in isolated rat hepatocytes. Incubation of hepatocytes with PFOS caused rapid depletion of hepatocyte glutathione (GSH), an important marker of cellular oxidative stress. Most of the PFOS-induced GSH depletion could be attributed to the expulsion of glutathione disulfide (GSSG). PFOS hepatotoxicity was inhibited by antioxidants and ROS scavengers, mitochondrial permeability transition (MPT) pore sealing agents, and endocytosis inhibitors. Our results suggest that PFOS hepatotoxicity might be the result of oxidative stress-induced lysosomal membrane leakiness and cellular proteolysis in rat hepatocytes.
Mostrar más [+] Menos [-]Bioreductive deposition of highly dispersed Ag nanoparticles on carbon nanotubes with enhanced catalytic degradation for 4-nitrophenol assisted by Shewanella oneidensis MR-1 Texto completo
2017
Song, Xiaojie | Shi, Xianyang
Biogenetic nanomaterials research provides insights and valuable implications for the green synthesis of nanomaterials and auxiliary biodegradation behaviors. Ag nanoparticles (Ag NPs) fabricated on multiwalled carbon nanotubes (MWNTs) (Ag/MWNTs nanocomposites) are prepared in situ assisted by Shewanella oneidensis MR-1 (S. oneidensis MR-1) that provide respiratory pathway to transmit electrons. The Ag/MWNTs nanocomposites are characterized by a scanning electron microscopy (SEM), an energy dispersive X-ray (EDX), a transmission electron microscopy (TEM), an X-ray diffraction (XRD), and an X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that Ag NPs (less than 20 nm in diameter) are successfully formed on the MWNTs without an aggregation. In application studies, the catalytic activities of the Ag/MWNTs nanocomposites towards the reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH₄) are tracked by a UV-visible spectroscopy. It is suggested that the Ag/MWNTs nanocomposites exhibit a satisfactory catalytic efficiency, which might be ascribed to the high dispersion of Ag NPs on MWNT surfaces. Moreover, the final results indicate that only after 10 min of reaction, the catalytic degradation ratio of 4-NP reaches 94.0% in the presence of Ag/MWNTs nanocomposites assisted by S. oneidensis MR-1.
Mostrar más [+] Menos [-]Market segmentation and industry overcapacity considering input resources and environmental costs through the lens of governmental intervention Texto completo
2017
The problems with China’s regional industrial overcapacity are often influenced by local governments. This study constructs a framework that includes the resource and environmental costs to analyze overcapacity using the non-radial direction distance function and the price method to measure industrial capacity utilization and market segmentation in 29 provinces in China from 2002 to 2014. The empirical analysis of the spatial panel econometric model shows that (1) the industrial capacity utilization in China’s provinces has a ladder-type distribution with a gradual decrease from east to west and there is a severe overcapacity in the traditional heavy industry areas; (2) local government intervention has serious negative effects on regional industry utilization and factor market segmentation more significantly inhibits the utilization rate of regional industry than commodity market segmentation; (3) economic openness improves the utilization rate of industrial capacity while the internet penetration rate and regional environmental management investment have no significant impact; and(4) a higher degree of openness and active private economic development have a positive spatial spillover effect, while there is a significant negative spatial spillover effect from local government intervention and industrial structure sophistication. This paper includes the impact of resources and the environment in overcapacity evaluations, which should guide sustainable development in emerging economies.
Mostrar más [+] Menos [-]Analysis of the environmental issues concerning the deployment of an OTEC power plant in Martinique Texto completo
2017
Devault, Damien A. | Péné-Annette, Anne
Ocean thermal energy conversion (OTEC) is a form of power generation, which exploits the temperature difference between warm surface seawater and cold deep seawater. Suitable conditions for OTEC occur in deep warm seas, especially the Caribbean, the Red Sea and parts of the Indo-Pacific Ocean. The continuous power provided by this renewable power source makes a useful contribution to a renewable energy mix because of the intermittence of the other major renewable power sources, i.e. solar or wind power. Industrial-scale OTEC power plants have simply not been built. However, recent innovations and greater political awareness of power transition to renewable energy sources have strengthened the support for such power plants and, after preliminary studies in the Reunion Island (Indian Ocean), the Martinique Island (West Indies) has been selected for the development of the first full-size OTEC power plant in the world, to be a showcase for testing and demonstration. An OTEC plant, even if the energy produced is cheap, calls for high initial capital investment. However, this technology is of interest mainly in tropical areas where funding is limited. The cost of innovations to create an operational OTEC plant has to be amortized, and this technology remains expensive. This paper will discuss the heuristic, technical and socio-economic limits and consequences of deploying an OTEC plant in Martinique to highlight respectively the impact of the OTEC plant on the environment the impact of the environment on the OTEC plant. After defining OTEC, we will describe the different constraints relating to the setting up of the first operational-scale plant worldwide. This includes the investigations performed (reporting declassified data), the political context and the local acceptance of the project. We will then provide an overview of the processes involved in the OTEC plant and discuss the feasibility of future OTEC installations. We will also list the extensive marine investigations required prior to installation and the dangers of setting up OTEC plants in inappropriate locations.
Mostrar más [+] Menos [-]Antibiotic resistance genes in an urban river as impacted by bacterial community and physicochemical parameters Texto completo
2017
Antibiotic resistance genes (ARGs) in urban rivers are a serious public health concern in regions with poorly planned, rapid development. To gain insights into the predominant factors affecting the fate of ARGs in a highly polluted urban river in eastern China, a total of 285 ARGs, microbial communities, and 20 physicochemical parameters were analyzed for 17 sites. A total of 258 unique ARGs were detected using high-throughput qPCR, and the absolute abundance of total ARGs was positively correlated with total organic carbon and total dissolved nitrogen concentrations (P < 0.01). ARG abundance and diversity were greatly altered by microbial community structure. Variation partitioning analysis showed that the combined effects of multiple factors contributed to the profile and dissemination of ARGs, and variation of microbial communities was the major factor affecting the distribution of ARGs. The disparate distribution of some bacteria, including Bacteroides from mammalian gastrointestinal flora, Burkholderia from zoonotic infectious diseases, and Zoogloea from wastewater treatment, indicates that the urban river was strongly influenced by point-source pollution. Results imply that microbial community shifts caused by changes in water quality may lead to the spread of ARGs, and point-source pollution in urban rivers requires greater attention to control the transfer of ARGs between environmental bacteria and pathogens.
Mostrar más [+] Menos [-]Wide band gap Ga2O3 as efficient UV-C photocatalyst for gas-phase degradation applications Texto completo
2017
α, β, γ, and δ polymorphs of 4.6–4.8 eV wide band gap Ga₂O₃ photocatalysts were prepared via a soft chemistry route. Their photocatalytic activity under 254 nm UV-C light in the degradation of gaseous toluene was strongly depending on the polymorph phase. α- and β-Ga₂O₃ photocatalysts enabled achieving high and stable conversions of toluene with selectivities to CO₂ within the 50–90% range, by contrast to conventional TiO₂ photocatalysts that fully deactivate very rapidly on stream in similar operating conditions with rather no CO₂ production, no matter whether UV-A or UV-C light was used. The highest performances were achieved on the high specific surface area β-Ga₂O₃ photocatalyst synthesized by adding polyethylene glycol (PEG) as porogen before precipitation, with stable toluene conversion and mineralization rate into CO₂ strongly overcoming those obtained on commercial β-Ga₂O₃. They were attributed to favorable physicochemical properties in terms of high specific surface area, small mean crystallite size, good crystallinity, high pore volume with large size mesopore distribution and appropriate surface acidity, and to the possible existence of a double local internal field within Ga³⁺ units. In the degradation of hydrogen sulfide, PEG-derived β-Ga₂O₃ takes advantage from its high specific surface area for storing sulfate, and thus for increasing its resistance to deactivation and the duration at total sulfur removal when compared to other β-Ga₂O₃ photocatalysts. So, we illustrated the interest of using high surface area β-Ga₂O₃ in environmental photocatalysis for gas-phase depollution applications.
Mostrar más [+] Menos [-]Bentonite supplementation can improve performance and fermentation parameters of chronic lead-exposed lambs Texto completo
2017
Azadbakht, S. | Khadem, A. A. | Norouzian, M. A.
Two experiments were conducted to investigate the effect of supplemental bentonite on performance, blood, and fermentation characteristics in Zandi lambs. In experiment 1, 20 Zandi male lambs (initial BW, 17.5 ± 1.6 kg and 110 ± 5 days old) were randomly assigned into four groups of five animals in each. The experimental treatments were (1) control (no Pb and bentonite), (2) 15 mg/kg DM Pb as Pb acetate and no bentonite, (3) 15 mg/kg DM Pb as Pb acetate and 1.5% bentonite, and (4) 15 mg/kg DM Pb as Pb acetate and 3% bentonite. The dietary treatments had no significant effect on dry matter intake of experimental lambs. Feed required per unit of weight gain was more (P < 0.05) in lead-exposed lambs in group 2 compared to the control and bentonite supplemented groups. Serum glucose, urea nitrogen, cholesterol, HDL, and LDL concentrations was similar among the treatments. In experiment 2, an in vitro gas production technique was used to evaluate the effects of bentonite supplementation on the gas production parameters of lead-polluted diets. The rate and amount of gas production was higher for bentonite supplemented groups (P < 0.01). Asymptotic gas production (b), metabolizable energy, and concentration of short chain fatty acids were lower (P < 0.05) for lead-polluted non-supplemented diet (group 2) as compared to the bentonite supplemented and control groups. It was concluded that bentonite supplementation favorably modified ruminal fermentation pattern and improved feed conversion ratio in growing lead-exposed lambs.
Mostrar más [+] Menos [-]Hepatoprotective and nephroprotective effects of sardinelle (Sardinella aurita) protein hydrolysate against ethanol-induced oxidative stress in rats Texto completo
2017
Kamoun, Zeineb | Kamoun, Alya Sellami | Bougatef, Ali | Kharrat, Rim Marrakchi | Youssfi, Houssem | Boudawara, Tahia | Chakroun, Mouna | Nasri, Moncef | Zeghal, Najiba
Ethanol consumption-induced oxidative stress that is a major etiological factor has been proven to play important roles in organs’ injury. In the present study, we investigated the protective effect of fish protein hydrolysate prepared from the heads and viscera of sardinelle (Sardinella aurita) (SPH) against the toxicity of ethanol on the liver and kidney of adult male rats. Animals were divided into four groups of six animals each: group C served as control, group Eth received 30 % ethanol solution at the dose of 3 g/kg body weight, group SPH received only 7.27 mg of SPH/kg body weight, and group Eth-SPH received ethanol and SPH simultaneously at the doses of 30 % and 7.27 mg/kg body weight, respectively. All groups were treated by gavage way for 15 days. Ethanol treatment decreased the defense enzymatic system including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), which increased after the co-administration of SPH. Malondialdehyde (MDA) and toxicity biomarker levels such as aspartate transaminase (AST) and alanine transaminase (ALT) and alcaline phosphatase (ALP) and gamma-glutamyl transaminase (GGT) activities were enhanced after chronic ethanol treatment and reduced by co-treatment with SPH. The histological examination of the liver and kidney confirmed biochemical changes in ethanol-treated rats and demonstrated the protective role of SPH.
Mostrar más [+] Menos [-]Nanostructured ZnO-TiO2 thin film oxide as anode material in electrooxidation of organic pollutants. Application to the removal of dye Amido black 10B from water Texto completo
2017
El-Kacemi, Sana | Zazou, Hicham | Oturan, Nihal | Dietze, Matthias | Hamdani, Mohamed | Es-Souni, Mohammed | Oturan, Mehmet A.
Electrochemical oxidative degradation of diazo dye Amido black 10B (AB10B) as model pollutant in water has been studied using nanostructured ZnO-TiO₂ thin films deposited on graphite felt (GrF) substrate as anode. The influence of various operating parameters, namely the current intensity, the nature and concentration of catalyst, the nature of electrode materials (anode/cathode), and the adsorption of dye and ambient light were investigated. It was found that the oxidative degradation of AB10B followed pseudo first-order kinetics. The optimal operating conditions for the degradation of 0.12 mM (74 mg L⁻¹) dye concentration and mineralization of its aqueous solution were determined as GrF-ZnO-TiO₂ thin film anode, 100 mA current intensity, and 0.1 mM Fe²⁺ (catalyst) concentration. Under these operating conditions, discoloration of AB10B solution was reached at 60 min while 6 h treatment needed for a mineralization degree of 91 %. Therefore, this study confirmed that the electrochemical process is effective for the degradation of AB10B in water using nanostructured ZnO-TiO₂ thin film anodes.
Mostrar más [+] Menos [-]Calcium polysulphide, its applications and emerging risk of environmental pollution—a review article Texto completo
2017
Dahlawi, Saad Mohammed | Siddiqui, Samreen
Easy availability, preparation technique, and economic value make calcium polysulphide (CaS ₓ) a very useful inorganic chemical for various field and industrial applications. In this article, disparate applications of CaS ₓ solution have been reviewed to suggest potential and future consolidation. This article also encompasses the physiochemical properties and production of CaS ₓ solution, with critical appraisal on research focusing on CaS ₓ application in agriculture industries and removal of potentially toxic elements (PTEs) from the environment. The kinetics of CaS ₓ , technical issues associated with optimization of its dosage and environmental fate is also discussed in detail. This study covers almost all of the peer-reviewed research that has been performed since 1914. Some of the critiques in this article include the lack of integration between the exposure effect and the efficiency of treatment method, effects of oxidizing environments on the long-term performance of CaS ₓ solution, and kinetics of CaS ₓ solution with the PTEs. The working model of CaS ₓ with PTEs is still system dependent, and therefore cannot be used with other applications. The kinetics of CaS ₓ is described in detail with various phase stoichiometric reactions. Environmental fate is discussed based on applications, government reports, peer-reviewed articles and kinetics of CaS ₓ , which provides a clear picture of emerging contaminants in the environment in relation to the insect resistance and ecotoxicology. Real time, lab based research articles are needed to identify toxicity limits of CaS ₓ in environment in order to describe its effective permissible limit in environmental system. This review article provides a risk assessment of environmental pollution by CaS ₓ based on its physicochemical characteristic, stoichiometry, kinetics, field, and industrial applications.
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