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Resultados 4111-4120 de 5,153
Regulatory role of miR-18a to CCN2 by TGF-β1 signaling pathway in pulmonary injury induced by nano-SiO2 Texto completo
2018
Yang, Hong | Li, Wenchao | Zhang, Yingjian | Li, Mingyue | Gao, Ying | Lao, Canshan | Shi, Bing
This research is designed to investigate the regulatory effect of miR-18a to the target gene connective tissue growth factor (CTGF, or CCN2), by participating in TGF-β1 signaling pathway and explore the pathogenic mechanism of miR-18a in pulmonary injury induced by nano-SiO₂ based on our early study. miR-18a and expression of TGF-β1 in Chinese hamster lung (CHL) fibroblasts cells stimulated by supernatants of NR8383 cells exposed to 40 μg/ml nano-SiO₂ for 24 h demonstrated 1.58 ± 0.22-fold and 1096.00 ± 2.60 pg/ml increase compared with blank control group analyzed by real-time quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Expression increase of miR-18a and reduction of CCN2 mRNA expression levels and protein gray value ratio detected by Western blotting in CHL cells transfect miR-18a mimics for 48 h. The reverse of CHL cell transfection miR-18a inhibit is also true. The result of miR-18a and CCN2 binding sites tested by luciferase reporter gene assay shows that the report relative fluorescence value of miR-18a mimics wild type on CCN2 is 0.50 ± 0.02 with the control of mimics NC and mutant relative fluorescence report value 0.86 ± 0.04 (P < 0.05). Expression levels of miR-18a, CCN2 mRNA, and protein gray value ratio decreased in CHL cells treated by TGF-β1, respectively, and vice versa treated by TGF-β1corepressor. The results suggest that CCN2 is the target gene regulated by miR-18a and miR-18a participates in TGF-β1 signaling pathway by regulating the expression of CCN2 negatively through CCN2 3’UTR site, and thus may be involved in the development process of pulmonary injury.
Mostrar más [+] Menos [-]Cytotoxicity of silver and copper nanoparticles on rainbow trout (Oncorhynchus mykiss) hepatocytes Texto completo
2018
Ostaszewska, Teresa | Śliwiński, Jerzy | Kamaszewski, Maciej | Sysa, Paweł | Chojnacki, Maciej
Nanoparticles are commonly used in the industry and are present in consumer goods; therefore, evaluation of their potential toxicity is necessary. The aim of the present study was to assess the cytotoxic effects of the nanoparticles of silver (AgNPs) at the concentration of 1.5 mg L⁻¹ and copper (CuNPs) at 0.15 mg L⁻¹ on rainbow trout (Oncorhynchus mykiss) hepatocytes after 28 days of exposure. Histological analysis revealed dilated sinusoids, shrunken hepatocytes, nuclear necrosis, and increased number of Kupffer cells in the liver of fish exposed to nanoparticles. The lowest hepatocyte proliferation index was observed in fish treated with AgNPs. Ultrastructural studies revealed mitochondrial edema and cristolysis, dilated and loosened endoplasmic reticulum, cytoplasm vacuolation, accumulation of lipid droplets, glycogen depletion, and formation of myelin-like bodies. The results also revealed that the liver of fish exposed to copper nanoparticles showed higher regenerative potential indicated by higher proliferation index, more abundant glycogen, and more numerous Kupffer cells compared to the fish treated with silver nanoparticles.
Mostrar más [+] Menos [-]Study of plasma off-gas treatment from spent ion exchange resin pyrolysis Texto completo
2018
Castro, Hernán Ariel | Luca, Vittorio | Bianchi, Hugo Luis
Polystyrene divinylbenzene-based ion exchange resins are employed extensively within nuclear power plants (NPPs) and research reactors for purification and chemical control of the cooling water system. To maintain the highest possible water quality, the resins are regularly replaced as they become contaminated with a range of isotopes derived from compromised fuel elements as well as corrosion and activation products including ¹⁴C, ⁶⁰Co, ⁹⁰Sr, ¹²⁹I, and ¹³⁷Cs. Such spent resins constitute a major proportion (in volume terms) of the solid radioactive waste generated by the nuclear industry. Several treatment and conditioning techniques have been developed with a view toward reducing the spent resin volume and generating a stable waste product suitable for long-term storage and disposal. Between them, pyrolysis emerges as an attractive option. Previous work of our group suggests that the pyrolysis treatment of the resins at low temperatures between 300 and 350 °C resulted in a stable waste product with a significant volume reduction (>50%) and characteristics suitable for long-term storage and/or disposal. However, another important issue to take into account is the complexity of the off-gas generated during the process and the different technical alternatives for its conditioning. Ongoing work addresses the characterization of the ion exchange resin treatment’s off-gas. Additionally, the application of plasma technology for the treatment of the off-gas current was studied as an alternative to more conventional processes utilizing oil- or gas-fired post-combustion chambers operating at temperatures in excess of 1000 °C. A laboratory-scale flow reactor, using inductively coupled plasma, operating under sub-atmospheric conditions was developed. Fundamental experiments using model compounds have been performed, demonstrating a high destruction and removal ratio (>99.99%) for different reaction media, at low reactor temperatures and moderate power consumption. The role of H₂O as an important participant of the oxidation mechanisms in plasma conditions was established. The combination of both processes could represent a simple, safe, and effective alternative for treating spent ion exchange resins with a large reduction of generated gaseous byproducts in fuel cycle facilities where processes that utilize open flames are undesirable.
Mostrar más [+] Menos [-]Sludge char-to-fuel approaches based on the catalytic pyrolysis II: heat release Texto completo
2018
Qin, Jinyi | Jiao, Yijing | Li, Xiaoguang | Liu, Yunxiao | Lei, Yali | Gao, Junfa
The pyrolyzed sludge is concerned currently, while the produced higher heating value (HHV) is unclear yet. In this work, the effects of moisture content (MC), catalysts amount, and catalytic types on the HHV production were investigated. Based on the known fatty acids (FAs) and alcohol content, the heat release by catalytic and non-catalytic pyrolysis product was examined. A good correlation between the measured and calculated HHV in non-catalytic pyrolysis indicates that the method can effectively evaluate the pyrolysis effect. The results show that a higher HHV can be obtained by adding a catalyst when the MC was between 20 and 40% compared to the non-catalytic pyrolysis. In the catalytic pyrolysis, the maximum HHV produced by bentonite is 50.61 MJ kg⁻¹. Bentonite can rapidly initiate the decarboxylation but sand was a potential efficient catalyst because of the enrichment of large amounts of FAs C₁₆:₀. If sand is used in combination with bentonite, C₁₆:₀ may be enriched and further decarboxylated, eventually releasing more heat. Since sand is composed of SiO₂ and Al₂O₃, in the production of HHV, the addition of Al₂O₃ has a better catalytic effect than adding SiO₂. For the evaluation of catalytic pyrolysis products and HHV, it is proposed that the possibility of adding two types of catalysts for pyrolysis is of great significance for realizing sludge to the fuel.
Mostrar más [+] Menos [-]Mechanisms of copper stress alleviation in Citrus trees after metal uptake by leaves or roots Texto completo
2018
Hippler, FranzWalter Rieger | Petená, Guilherme | Boaretto, RodrigoMarcelli | Quaggio, JoséAntônio | Azevedo, RicardoAntunes | Mattos-Jr, Dirceu
Nutritional disorders caused by copper (Cu) have affected citrus orchards. Since Cu is foliar sprayed as a pesticide to control citrus diseases, this metal accumulates in the soil. Thereby, we evaluated the effects of Cu leaf absorption after spray of different metal sources, as well as roots absorption on growth, nutritional status, and oxidative stress of young sweet orange trees. Two experiments were carried out under greenhouse conditions. The first experiment was set up with varying Cu levels to the soil (nil Cu, 0.5, 2.0, 4.0 and 8.0 g of Cu per plant as CuSO₄.5H₂O), whereas the second experiment with Cu application via foliar sprays (0.5 and 2.0 g of Cu per plant) and comparing two metal sources (CuSO₄.5H₂O or Cu(OH)₂). Copper was mainly accumulated in roots with soil supply, but an increase of oxidative stress levels was observed in leaves. On the other hand, Cu concentrations were higher in leaves that received foliar sprays, mainly as Cu(OH)₂. However, when sulfate was foliar sprayed, plants exhibited more symptoms of injuries in the canopy with decreased chlorophyll contents and increased hydrogen peroxide and lipid peroxidation levels. Copper toxicity was characterized by sap leakage from the trunk and twigs, which is the first report of this specific Cu excess symptom in woody trees. Despite plants with 8.0 g of Cu soil-applied exhibiting the sap leakage, growth of new plant parts was more vigorous with lower oxidative stress levels and injuries compared to those with 4.0 g of Cu soil-applied (without sap leakage). With the highest level of Cu applied via foliar as sulfate, Cu was eliminated by plant roots, increasing the rhizospheric soil metal levels. Despite citrus likely exhibiting different mechanisms to reduce the damages caused by metal toxicity, such as responsive enzymatic antioxidant system, metal accumulation in the roots, and metal exclusion by roots, excess Cu resulted in damages on plant growth and metabolism when the metal was taken up either by roots or leaves.
Mostrar más [+] Menos [-]Fungi extracellular enzyme-containing microcapsules enhance degradation of sulfonamide antibiotics in mangrove sediments Texto completo
2018
Yang, Chu-Wen | Tsai, Li-Ling | Chang, Bea-Ven
Mangroves represent a special coastal vegetation along the coastlines of tropical and subtropical regions. Sulfonamide antibiotics (SAs) are the most commonly used antibiotics. The application of white-rot fungi extracellular enzyme-containing microcapsules (MC) for aerobic degradation of SAs in mangrove sediments was investigated in this study. Degradation of three SAs, sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfamethazine (SMZ), was enhanced by adding MC to the sediments. The order of SA degradation in batch experiments was SMX > SDM > SMZ. Bioreactor experiments revealed that SA removal rates were higher with than without MC. The enhanced SA removal rates with MC persisted with three re-additions of SAs. Thirteen bacteria genera (Achromobacter, Acinetobacter, Alcaligenes, Aquamicrobium, Arthrobacter, Brevundimonas, Flavobacterium, Methylobacterium, Microbacterium, Oligotropha, Paracoccus, Pseudomonas, and Rhodococcus) were identified to be associated with SA degradation in mangrove sediments by combination of next-generation sequencing, bacterial strain isolation, and literature search results. Results of this study suggest that MC could be used for SA removal in mangrove sediments.
Mostrar más [+] Menos [-]Review of the methods for determination of reactive oxygen species and suggestion for their application in advanced oxidation induced by dielectric barrier discharges Texto completo
2018
Massima Mouele, EmileS. | Fatoba, OlanrewajuOjo | Babajide, Omotola | Badmus, KassimO. | Petrik, LeslieF.
Advanced oxidation processes (AOPs) particularly non-thermal plasmas based on electrical discharges have been widely investigated for water and wastewater treatment. Dielectric barrier discharges (DBDs) generate large amounts of selective and non-selective reactive oxygen species (ROS) such as ozone, hydrogen peroxide, atomic oxygen, superoxide molecular anions and hydroxyl radicals, having been proved to be efficient for water decontamination among various forms of electrical discharge systems. The detection and quantification methods of these oxygen species in non-thermal plasmas have been reviewed. However, their application in dielectric barrier discharge has not been well studied. It is therefore imperative to summarise the various detection and quantification methods for oxygen-based species determination in AOPs, aqueous systems and non-thermal plasma processes. Thereafter, reviewed methods are suggested for the determination of ROS in DBD configurations to understand the consumption trend of these oxidants during treatment of water effluents and to evaluate the performance of the treatment reactor configuration towards the degradation of targeted pollutants.
Mostrar más [+] Menos [-]Enantioselective degradation of Myclobutanil and Famoxadone in grape Texto completo
2018
Lin, Chunmian | Zhang, Lijun | Zhang, Hu | Wang, Qiang | Zhu, Jiahong | Wang, Jianmei | Qian, Mingrong
The enantioselective degradation of myclobutanil and famoxadone enantiomers in grape under open field was investigated in this study. The absolute configuration of myclobutanil and famoxadone enantiomers was determined by the combination of experimental electronic circular dichroism (ECD) and calculated ECD spectra. The enantiomers residues of myclobutanil and famoxadone in grape were measured by sensitive high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS). The linearity, precision, accuracy, matrix effect, and stability were assessed. And the limit of quantification (LOQ) for each enantiomer of myclobutanil and famoxadone in grape was evaluated to be 1.5 and 2 μg kg⁻¹. The myclobutanil and famoxadone showed the enantioselective degradation in grape, and the enantioselectivity of degradation for myclobutanil was more pronounced than that for famoxadone. The half-lives were 13.1 days and 25.7 days for S-(+)-myclobutanil and R-(−)-myclobutanil in grape, separately. The half-life of S-(+)-famoxadone was 31.5 days slightly shorter than that of R-(−)-famoxadone with half-life being 38.5 days in grape. The probable reasons for the enantioselective degradation behavior of these two fungicides were also discussed. The results in the article might provide a reference to better assess the risks of myclobutanil and famoxadone enantiomers in grapes to human and environment. Graphical abstract The enantioselective analysis of myclobutanil and famoxadone in grape
Mostrar más [+] Menos [-]Elimination and detoxification of 2,4-D by Umbelopsis isabellina with the involvement of cytochrome P450 Texto completo
2018
Nykiel-Szymańska, Justyna | Stolarek, Paulina | Bernat, Przemysław
The chemical 2,4-dichlorophenoxyacetic acid (2,4-D) is used in agriculture as a herbicide. Its intensive use has an adverse effect on the environment. This study involved examining the degradation of 2,4-D compound by the filamentous fungus Umbelopsis isabellina. After 5 days of incubation, 98% of the herbicide (added at 25 mg L⁻¹) was found to be removed. The elimination of 2,4-D by U. isabellina was connected with the formation of 2,4-dichlorophenol (2,4-DCP), which resulted in a 60% decrease in the sample toxicity toward Artemia franciscana larvae. The metabolism of 2,4-D was inhibited by the addition of metyrapone, a known cytochrome P450 inhibitor. It provides evidence that cytochrome P450 system is involved in 2,4-D metabolism in U. isabellina.
Mostrar más [+] Menos [-]Sonocatalytic removal of methylene blue from water solution by cobalt ferrite/mesoporous graphitic carbon nitride (CoFe2O4/mpg-C3N4) nanocomposites: response surface methodology approach Texto completo
2018
Hassani, Aydin | Eghbali, Paria | Metin, Önder
In this study, cobalt ferrite/mesoporous graphitic carbon nitride (CoFe₂O₄/mpg-C₃N₄) nanocomposites were successfully synthesized by using a two-step protocol. Firstly, monodispersed CoFe₂O₄ nanoparticles (NPs) were synthesized via thermal decomposition of metal precursors in a hot surfactant solution and then they were assembled on mpg-C₃N₄ via a liquid phase self-assembly method. The sonocatalytic performance of as-synthesized CoFe₂O₄/mpg-C₃N₄ nanocomposites was evaluated on the methylene blue (MB) removal from water under ultrasonic irradiation. For this purpose, response surface methodology (RSM) based on central composite design (CCD) model was successfully utilized to optimize the MB removal over CoFe₂O₄/mpg-C₃N₄ nanocomposites. Analysis of variance (ANOVA) was applied to investigate the significance of the model. The results predicted by the model were obtained to be in reasonable agreement with the experimental data (R² = 0.969, adjusted R² = 0.942). Pareto analysis demonstrated that pH of the solution was the most effective parameter on the sonocatalytic removal of MB by CoFe₂O₄/mpg-C₃N₄ nanocomposites. The optimum catalyst dose, initial dye concentration, pH, and sonication time were set as 0.25 g L⁻¹, 8 mg L⁻¹, 8, and 45 min, respectively. The high removal efficiency of MB dye (92.81%) was obtained under optimal conditions. The trapping experiments were done by using edetate disodium, tert-butyl alcohol, and benzoquinone. Among the reactive radicals, •OH played a more important role than h⁺ and [Formula: see text] in the MB dye removal process. Moreover, a proposed mechanism was also presented for the removal of MB in the presence of CoFe₂O₄/mpg-C₃N₄ nanocomposites under the optimized sonocatalytic conditions. Finally, a reusability test of the nanocomposites revealed a just 9.6% decrease in their removal efficiency after five consecutive runs.
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