خيارات البحث
النتائج 2511 - 2520 من 4,309
Investigations on the effects of etoxazole in the liver and kidney of Wistar rats النص الكامل
2017
Yılmaz, Mehmet | Rencuzogullari, Eyyup | Canli, Mustafa
Pesticides are used to protect crops and to eliminate pests, though non-target organisms such as mammals are also affected from their usage. Etoxazole (organoflourine pesticide) is an acaricide used to combat spider mites which are the parasites of various crops. The present study aims to investigate the effects of etoxazole on the level of MDA (malondialdehyde) and activities of CAT (catalase), GPx (glutathione peroxidase), and AChE (acetylcholinesterase) in liver and kidney tissues of Wistar rats (Rattus norvegicus var. albinos). Rats received etoxazole intraperitoneally with doses of 2.2, 11, and 22 mg/kg b.w./day for 21 days. Control rats received the same volume of the serum physiologic. Following etoxazole exposures, activities of CAT, GPx, and AChE in the liver and kidney of rats significantly decreased at all doses compared to control group. Oppositely, MDA levels in these tissues increased significantly at all doses following etoxazole exposures. The present study demonstrated that etoxazole, at all doses, had toxic effects in the liver and kidney parameters, suggesting their possible use as effective biomarkers in determining the toxic effects of etoxazole. This may suggest that these biomarkers could also be used as a tool to monitor pesticide-affected areas before severe toxic effects begin in non-target animals and humans.
اظهر المزيد [+] اقل [-]Biodeterioration of Pompeian mural paintings: fungal colonization favoured by the presence of volcanic material residues النص الكامل
2017
Veneranda, Marco | Prieto-Taboada, Nagore | de Vallejuelo, SilviaFdez-Ortiz | Maguregui, Maite | Morillas, Hector | Marcaida, Iker | Castro, Kepa | Madariaga, JuanManuel | Osanna, Massimo
This work was focused on the study of the biodegradation processes jeopardizing a mural painting conserved in the basement of Ariadne House (archaeological site of Pompeii, Italy). The fresco stood out for its peculiar state of preservation: the upper part, recovered in 1988, was just barely colonized by microorganisms. On the contrary, the lower part (excavated in 2005) was almost completely covered by extensive biological patinas. The genomic characterization carried out by polymerase chain reaction (PCR) highlighted the presence of seven different fungi strains on the mural surface. Beside, in situ and laboratory analyses were performed with the purpose of identifying the causes of the heterogeneous spatial distribution of the biopatinas. The in situ Raman spectroscopy and energy dispersive X-ray fluorescence (ED-XRF) spectroscopy measurements excluded any link between the heterogeneous colonization and the original materials present in the wall. On the other side, X-ray diffraction (XRD) and scanning electron microscopy (SEM) on microsamples proved the presence of a thin volcanic material layer overlying the lower part of the fresco. Considering that most of the biofilms of the studied mural painting only growth over these residues, it was confirmed the role of volcanic material as a suitable support for biological colonization. Thanks to the obtained results, this research helped to understand more in depth an important degradation pathway threatening the artworks from one of the most important archaeological sites in the world.
اظهر المزيد [+] اقل [-]Analysis of certain fatty acids and toxic metal bioaccumulation in various tissues of three fish species that are consumed by Turkish people النص الكامل
2017
Kaya, Gökçe | Türkoğlu, Semra
Concentrations of toxic metals (Mn, Ni, Hg, Cd, Pb, Cr) in the muscle, skin, and liver of Mugil cephalus, Mullus barbatus, and Pagellus erythrinus which were purchased in large supermarkets of Elazig, and Mullus barbatus, which were caught on the sea of İskenderun Bay, Turkey, were analyzed. Fundamental analyses were carried out by inductively coupled plasma-mass spectrometry (ICP-MS) after samples were prepared by microwave digestion. Mean metal concentrations in different tissues were varied in the ranges of Cd 4–426, Cr 116–4458, Mn 141–24774, Hg 9–471, Pb 96–695, and Ni 68–6581 μg kg⁻¹, for wet weight. The investigated metal bioaccumulation in the muscles of fish species, in general, was lower than those in the liver and skin. This method was verified by NCS ZC73016 chicken trace element-certified reference material analysis. In addition, fatty acids in the muscles of three fish species were analyzed. According to the gas chromatography (GC) results of fatty acids, the monounsaturated fatty acids (MUFA) were found to be between 23.76 and 31.97%. The fatty acids’ polyunsaturated fatty acids (PUFA) ratio was found to be between 13.67 and 30.71% and saturated fatty acids ratios were determined in the range of 24.06–32.30%. In all fish species, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ratio, which increase the value of these fish species, were high. These results show that these three fish species are good sources of fatty acids.
اظهر المزيد [+] اقل [-]Interactional effect of cerium and manganese on NO catalytic oxidation النص الكامل
2017
Liang, Yanli | Huang, Yufen | Zhang, Hailong | Lan, Li | Zhao, Ming | Gong, Maochu | Chen, Yaoqiang | Wang, Jianli
To preferably catalyze the oxidation of NO to NO₂ in diesel after-treatment system, a series of CeO₂-MnO ₓ composite oxides was supported on silica-alumina material by the co-impregnation method. The maximum conversion of NO of the catalyst with a Ce/Mn weight ratio of 5:5 was improved by around 40%, compared to the supported manganese-only or cerium-only sample. And its maximum reaction rate was 0.056 μmol g⁻¹ s⁻¹ at 250 °C at the gas hourly space velocity of 30,000 h⁻¹. The experimental results suggested that Ce-Mn solid solution was formed, which could modulate the valence state of cerium and manganese and exhibit great redox properties. Moreover, the strong interaction between ceria and manganese resulted in the largest desorption amount of strong chemical oxygen and oxygen vacancies, leading to the maximum O α area ratio of 62.26% from the O 1s result. These effective oxygen species could be continually transferred to the surface, leading to the best NO catalytic activity of 5Ce5Mn/SA catalyst. Graphical abstract
اظهر المزيد [+] اقل [-]Perfluoroalkyl acids in aqueous samples from Germany and Kenya النص الكامل
2017
Shafique, Umer | Schulze, Stefanie | Slawik, Christian | Böhme, Alexander | Paschke, Albrecht | Schüürmann, Gerrit
Continuous monitoring of chemicals in the environment is important to control their fate and to protect human health, flora, and fauna. Perfluoroalkyl acids (PFAAs) have been detected frequently in different environmental compartments during the last 15 years and have drawn much attention because of their environmental persistence, omnipresence, and bioaccumulation potential. Water is an important source of their transport. In the present study, distributions of PFAAs in river water, wastewater treatment plant (WWTP) effluent, and tap water from eastern part of Germany and western part of Kenya were investigated. Eleven perfluorocarboxylic acids (PFCAs) and five perfluorosulfonic acids (PFSAs) were analyzed using liquid chromatography/tandem mass spectrometry. Sum of mean concentrations of eight PFAAs detected in drinking tap water from Leipzig was 11.5 ng L–¹, dominated by perfluorooctanoic acid (PFOA, 6.2 ng L–¹). Sums of mean riverine concentrations of PFAAs detected in Pleiße/White Elster, Saale, and Elbe (Germany) were 24.8, 54.3, and 26.8 ng L–¹, respectively. Annual flux of PFAAs from River Saale was estimated to be 164 ± 23 kg a–¹. The effluent of WWTP in Halle was found to contain four times higher levels of PFAAs than river water and was dominated by perfluorobutane sulfonate (PFBS) with 32 times higher concentration than the riverine level. It advocates that WWTPs are the point source of contaminating water bodies with PFAAs, and short-chain PFAAs are substituting long-chain homologues. Sums of mean riverine concentrations of PFAAs in Sosiani (Kenya) in samples from sparsely populated and densely populated areas were 58.8 and 109.4 ng L–¹, respectively, indicating that population directly affected the emissions of PFAAs to surface waters. The discussion includes thorough review and comparison of recently published literature reporting occurrence of PFAAs in aqueous matrices. Graphical abstract Perfluoroalkyl acids in aqueous matrices
اظهر المزيد [+] اقل [-]Titanium dioxide solid phase for inorganic species adsorption and determination: the case of arsenic النص الكامل
2017
Véra, R. | Fontàs, C. | Anticó, E.
We have evaluated a new titanium dioxide (Adsorbsia As600) for the adsorption of both inorganic As (V) and As (III) species. In order to characterize the sorbent, batch experiments were undertaken to determine the capacities of As (III) and As (V) at pH 7.3, which were found to be 0.21 and 0.14 mmol g⁻¹, respectively. Elution of adsorbed species was only possible using basic solutions, and arsenic desorbed under batch conditions was 50 % when 60 mg of loaded titanium dioxide was treated with 0.5 M NaOH solution. Moreover, its use as a sorbent for solid-phase extraction and preconcentration of arsenic species from well waters has been investigated, without any previous pretreatment of the sample. Solid-phase extraction was implemented by packing several minicolumns with Adsorbsia As600. The method has been validated showing good accuracy and precision. Acceptable recoveries were obtained when spiked waters at 100–200 μg L⁻¹ were measured. The presence of major anions commonly found in waters did not affect arsenic adsoption, and only silicate at 100 mg L⁻¹ level severely competed with arsenic species to bind to the material. Finally, the measured concentrations in water samples containing arsenic from the Pyrinees (Catalonia, Spain) showed good agreement with the ICP-MS results.
اظهر المزيد [+] اقل [-]Nitrogen nutrition in cotton and control strategies for greenhouse gas emissions: a review النص الكامل
2017
Khan, Aziz | Tan, Daniel Kean Yuen | Munsif, Fazal | Afridi, Muhammad Zahir | Shah, Farooq | Wei, Fan | Shah, Fahad | Zhou, Ruiyang
Cotton (Gossypium hirustum L.) is grown globally as a major source of natural fiber. Nitrogen (N) management is cumbersome in cotton production systems; it has more impacts on yield, maturity, and lint quality of a cotton crop than other primary plant nutrient. Application and production of N fertilizers consume large amounts of energy, and excess application can cause environmental concerns, i.e., nitrate in ground water, and the production of nitrous oxide a highly potent greenhouse gas (GHG) to the atmosphere, which is a global concern. Therefore, improving nitrogen use efficiency (NUE) of cotton plant is critical in this context. Slow-release fertilizers (e.g., polymer-coated urea) have the potential to increase cotton yield and reduce environmental pollution due to more efficient use of nutrients. Limited literature is available on the mitigation of GHG emissions for cotton production. Therefore, this review focuses on the role of N fertilization, in cotton growth and GHG emission management strategies, and will assess, justify, and organize the researchable priorities. Nitrate and ammonium nitrogen are essential nutrients for successful crop production. Ammonia (NH₃) is a central intermediate in plant N metabolism. NH₃ is assimilated in cotton by the mediation of glutamine synthetase, glutamine (z-) oxoglutarate amino-transferase enzyme systems in two steps: the first step requires adenosine triphosphate (ATP) to add NH₃ to glutamate to form glutamine (Gln), and the second step transfers the NH₃ from glutamine (Gln) to α-ketoglutarate to form two glutamates. Once NH₃ has been incorporated into glutamate, it can be transferred to other carbon skeletons by various transaminases to form additional amino acids. The glutamate and glutamine formed can rapidly be used for the synthesis of low-molecular-weight organic N compounds (LMWONCs) such as amides, amino acids, ureides, amines, and peptides that are further synthesized into high-molecular-weight organic N compounds (HMWONCs) such as proteins and nucleic acids.
اظهر المزيد [+] اقل [-]Dissipation of spiromesifen and spiromesifen-enol on tomato fruit, tomato leaf, and soil under field and controlled environmental conditions النص الكامل
2017
Siddamallaiah, Lekha | Mohapatra, Soudamini | Buddidathi, Radhika | Hebbar, Shibara Shankara
Dissipation of spiromesifen and its metabolite, spiromesifen-enol, on tomato fruit, tomato leaf, and soil was studied in the open field and controlled environmental conditions. Sample preparation was carried out by QuEChERS method and analysis using LC-MS/MS. Method validation for analysis of the compounds was carried out as per “single laboratory method validation guidelines.” Method validation studies gave satisfactory recoveries for spiromesifen and spiromesifen-enol (71.59–105.3%) with relative standard deviation (RSD) < 20%. LOD and LOQ of the method were 0.0015 μg mL⁻¹ and 0.005 mg kg⁻¹, respectively. Spiromesifen residues on tomato fruits were 0.855 and 1.545 mg kg⁻¹ in open field and 0.976 and 1.670 mg kg⁻¹ under polyhouse condition, from treatments at the standard and double doses of 125 and 250 g a.i. ha⁻¹, respectively. On tomato leaves, the residues were 5.64 and 8.226 mg kg⁻¹ in open field and 6.874 and 10.187 mg kg⁻¹ in the polyhouse. In soil, the residues were 0.532 and 1.032 mg kg⁻¹ and 0.486 and 0.925 mg kg⁻¹ under open field and polyhouse conditions, respectively. The half-life of degradation of spiromesifen on tomato fruit was 6–6.5 days in the open field and 8.1–9.3 days in the polyhouse. On tomato leaves, it was 7–7.6 and 17.6–18.4 days and in soil 5.6–7.4 and 8.4–9.5 days, respectively. Metabolite, spiromesifen-enol, was not detected in any of the sample throughout the study period. Photodegradation could be the major route for dissipation of spiromesifen in the tomato leaves, whereas in the fruits, it may be the combination of photodegradation and dilution due to fruit growth. The results of the study can be utilized for application of spiromesifen in plant protection of tomato crop under protected environmental conditions.
اظهر المزيد [+] اقل [-]Molecular-based detection of potentially pathogenic bacteria in membrane bioreactor (MBR) systems treating municipal wastewater: a case study النص الكامل
2017
Harb, Moustapha | Hong, Pei-Ying
Although membrane bioreactor (MBR) systems provide better removal of pathogens compared to conventional activated sludge processes, they do not achieve total log removal. The present study examines two MBR systems treating municipal wastewater, one a full-scale MBR plant and the other a lab-scale anaerobic MBR. Both of these systems were operated using microfiltration (MF) polymeric membranes. High-throughput sequencing and digital PCR quantification were utilized to monitor the log removal values (LRVs) of associated pathogenic species and their abundance in the MBR effluents. Results showed that specific removal rates vary widely regardless of the system employed. Each of the two MBR effluents’ microbial communities contained genera associated with opportunistic pathogens (e.g., Pseudomonas, Acinetobacter) with a wide range of log reduction values (< 2 to >5.5). Digital PCR further confirmed that these bacterial groups included pathogenic species, in several instances at LRVs different than those for their respective genera. These results were used to evaluate the potential risks associated both with the reuse of the MBR effluents for irrigation purposes and with land application of the activated sludge from the full-scale MBR system.
اظهر المزيد [+] اقل [-]Performance and emission analysis on blends of diesel, restaurant yellow grease and n-pentanol in direct-injection diesel engine النص الكامل
2017
Ravikumar, J | Caravaṇan̲, Nallūr Cā.
Yellow grease from restaurants is typically waste cooking oil (WCO) free from suspended food particles with free fatty acid (FFA) content less than 15%. This study proposes an approach to formulate a renewable, eco-friendly fuel by recycling WCO with diesel (D) and n-pentanol (P) to improve fuel-spray characteristics. Three ternary blends (D50-WCO45-P5, D50-WCO40-P10 and D50-WCO30-P20) were selected based on the stability tests and prepared with an objective to substitute diesel by 50% with up to 45% recycled component (WCO) and up to 20% bio-component (n-pentanol) by volume. The fuel properties of these ternary blends were measured and compared. The emission impacts of these blends on a diesel engine were analysed in comparison with diesel and D50-WCO50 (50% of diesel + 50% of WCO) under naturally articulated and EGR (exhaust gas recirculation) approaches. Doping of n-pentanol showed improved fuel properties when compared to D50-WCO50. Viscosity is reduced up to 45%. Cetane number and density were comparable to that of diesel. Addition of n-pentanol to D50-WCO50 presented improved brake specific fuel consumption (BSFC) for all ternary blends. Brake thermal efficiency (BTE) of D50-WCO30-P20 blend is comparable to diesel due to improved atomization. Smoke opacity reduced, HC emissions increased and CO emissions remained unchanged with doping n-pentanol in the WCO. NOx emission increases with increase in n-pentanol and remained lower than diesel and all load conditions. However, NOx can be decreased by up to threefold using EGR. By adopting this approach, WCO can be effectively reused as a clean energy source by negating environmental hazards before and after its use in diesel engines, instead of being dumped into sewers and landfills.
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