خيارات البحث
النتائج 2901 - 2910 من 4,308
An inexact multistage fuzzy-stochastic programming for regional electric power system management constrained by environmental quality النص الكامل
2017
Fu, Zhenghui | Wang, Han | Lu, Wentao | Guo, Huaicheng | Li, Wei
Electric power system involves different fields and disciplines which addressed the economic system, energy system, and environment system. Inner uncertainty of this compound system would be an inevitable problem. Therefore, an inexact multistage fuzzy-stochastic programming (IMFSP) was developed for regional electric power system management constrained by environmental quality. A model which concluded interval-parameter programming, multistage stochastic programming, and fuzzy probability distribution was built to reflect the uncertain information and dynamic variation in the case study, and the scenarios under different credibility degrees were considered. For all scenarios under consideration, corrective actions were allowed to be taken dynamically in accordance with the pre-regulated policies and the uncertainties in reality. The results suggest that the methodology is applicable to handle the uncertainty of regional electric power management systems and help the decision makers to establish an effective development plan.
اظهر المزيد [+] اقل [-]Blood cadmium levels associated with short distant metastasis-free survival time in invasive breast cancer النص الكامل
2017
He, Yuanfang | Peng, Lin | Huang, Yanhong | Liu, Caixia | Zheng, Shukai | Wu, Kusheng
Distant metastasis is strongly associated with poor prognosis of breast cancer. Cadmium (Cd) exposure was previously found associated with breast cancer incidence. We explored the associations of blood cadmium levels (BCLs) and clinicopathologic characteristics with invasive breast cancer distant metastasis. Blood samples were collected and analyzed for BCLs by graphite-furnace atomic absorption spectrometry. Clinicopathologic characteristics, including basic clinical information and tumor characteristics, were obtained from medical records. Breast cancer distant metastasis-free survival (DMFS) time was calculated at follow-up. The associations of BCLs and clinicopathologic characteristics with DMFS time were examined by Kaplan–Meier method and Cox regression analysis, and associations between BCLs and tumor characteristics were also explored. Blood Cd level was positively associated with distant metastasis, clinical stage, BMI, and age. On univariate analysis, older age at diagnosis, family history of breast cancer, high N classification and clinical stage, positivity for human epidermal growth factor receptor 2, and high BCLs were associated with short DMFS time. On multivariate analysis model, older age at diagnosis, family history of breast cancer, high N classification, and BCLs were predictors for breast cancer distant metastasis. BCLs were a risk factor for short DMFS time of invasive breast cancer. BCLs and some clinicopathologic factors affect breast cancer distant metastasis, which needs further epidemiological and experimental studies to confirm.
اظهر المزيد [+] اقل [-]Released fraction of polychlorinated biphenyls from soil–biosolid system using a leaching procedure and its comparison with bioavailable fraction determined by wheat plant uptake النص الكامل
2017
Jachero, Lourdes | Leiva, Claudio | Ahumada, Inés | Richter, Pablo
The bioavailability of polychlorinated biphenyls (PCBs) in soils amended with biosolids was estimated using an aqueous leaching process of the compounds combined with rotating disk sorptive extraction (RDSE), and compared with bioavailability determined through of PCB absorption in wheat plants growing in the same soil–biosolid matrix. The matrices consisted of soil amended with biosolids at doses of 30, 90, and 200 Mg/ha, which increase concomitantly the organic matter content of the matrix. Considering that PCBs were natively absent in both the biosolids and soil used, the compounds were spiked in the biosolids and aged for 10 days. For each biosolid dose, the aqueous leaching profile was studied and equilibrium time was calculated to be 33 h. The leaching fractions determined by RDSE, considering total PCBs studied, were 12, 7, and 6% and the bioavailable fractions absorbed by the wheat root were found to be 0.5, 0.3, and 0.2% for 30, 90, and 200 Mg/ha doses, respectively. Both fractions leachable and bioavailable decrease with both increasing hydrophobicity of the compound (Kow) and increasing in the biosolid dose. It was found that both fractions (leaching and bioavailable) correlated according to the bivariate least squares regression, represented by a coefficient of correlation of 0.86. Therefore, the application of the chemical method involving a leaching procedure is an alternative to estimate the bioavailable fraction of PCBs in wheat plants in a simpler and in a shorter time.
اظهر المزيد [+] اقل [-]Leonardite-derived humic substances are great adsorbents for cadmium النص الكامل
2017
Meng, Fande | Yuan, Guodong | Wei, Jing | Bi, Dongxue | Wang, Hailong
Adsorption is an important mechanism to immobilize cadmium (Cd) in soil, for which humic substances have a potential. However, commercial humic substances are either very acidic (pH = 2) or alkaline/Na⁺-enriched, making them less suitable for use in acid and saline soils. Here, we used leonardite to produce humic adsorbents HA (pH = 4.02), Ca-HA (pH = 10.9), and Ca-CPAM-HA (pH = 9.62) by using HCl, CaCl₂, or CaCl₂-polyacrylamide as a flocculant. Their elemental compositions, acidity, and spectroscopic properties were determined, and their Cd adsorption characteristics were assessed by batch kinetic and thermodynamic experiments at environmentally relevant concentrations. Further, HA was mixed with Cd-contaminated soils and incubated for a month to assess its effect on Cd immobilization. Good fitting of kinetic adsorption data into pseudo-second-order model, together with FTIR spectroscopic data, suggested the chemisorption mechanism by forming Cd(II)-carboxyl complexes. The maximum adsorption capacity derived from the Langmuir equation was 129, 114, and 110 mg Cd(II)/g for HA, Ca-HA, and Ca-CPAM-HA, respectively. These values are almost the same on carbon-normalized basis. HA reduced acetic acid extractable Cd by 31% or more. Besides their high propensity for Cd adsorption, humic adsorbents are inexpensive, safe, and beneficial to soil quality.
اظهر المزيد [+] اقل [-]Distribution and controls of heavy metals and organic matter in the surface sediments of the Southern Yellow Sea, China النص الكامل
2017
Guo, Hui | Zhang, Shengyin | Zhang, Shuncun | Lu, Xinchuan | Li, Shuanglin
Accurate and effective determination of the source of heavy metals is essential for the treatment of marine ecological environments. This article attempts to combine geochemical composition data and hydrocarbon composition data to achieve this purpose. The concentrations of six heavy metals (Cu, Pb, Zn, Cr, Ni, and Co), grain size, total organic carbon (TOC) content, Al₂O₃ content, and aliphatic hydrocarbons (AHs) in 501 surface samples from the Southern Yellow Sea (SYS) were analyzed. The results showed that most sample sites ranged from not polluted to moderately polluted. However, Cu, Pb, Cr, and Ni may represent potential hazards, and the toxic probability for the combination of five metals (Cr, Cu, Ni, Zn, and Pb) was 21% for all sampling sites. The highest heavy metal concentrations were associated with the fine-grained sediments in the eastern area, especially in the northeastern muddy area. However, high concentrations of Pb and Cu were also found in some sites with coarse sediment in the western region. The lipid biomarkers showed that the n-alkanes were dominated by large odd-numbered carbon molecules, indicating that the organic matter in the sediments originated mainly from terrestrial plants. Principal component analysis (PCA) results, AH data, and the sediment distributions indicated that the organic matter and heavy metals in the SYS were mainly sourced from the Old Yellow River Delta, transported by ocean currents and deposited in the central SYS. In addition, a small proportion of the heavy metals originated from airborne dust. The spatial distribution pattern of the heavy metals in the surface sediments provides a basis for the protection of the marine ecological environments.
اظهر المزيد [+] اقل [-]Effects of cyproterone acetate and vertically transmitted microsporidia parasite on Gammarus pulex sperm production النص الكامل
2017
Gismondi, Eric | Fivet, Adeline | Joaquim-Justo, Célia
Endocrine disruption compounds (EDCs) and parasitism can both interfere with the reproduction process of organisms. The amphipod Gammarus pulex is the host of the vertically transmitted microsporidia Dictyocoela duebenum, and this work was devoted to the investigation of the effect of an exposure to the anti-androgen compound, cyproterone acetate (CPA), and/or of the presence of D. duebenum on the spermatozoa production and length. Significant reduction of the spermatozoa production was observed when G. pulex males were uninfected and exposed to CPA. There also appeared a lower number of spermatozoa when D. duebenum infects G. pulex, whatever the exposure condition. Moreover, we highlighted that CPA has no effect on spermatozoa production when males are infected by D. duebenum, and no treatment has impacted the spermatozoa length. Our results suggest CPA and D. duebenum could impact the endocrine system of G. pulex and especially processes close to the spermatozoa production (e.g., androgenic gland, androgen gland hormone released, gonad-inhibiting hormone synthesized by X-organ). However, as no mechanism of action was highlighted, further testing need to be performed to improve the understanding of their impacts. Finally, results confirm that vertically transmitted microsporidia could be a confounding factor in the endocrine disruption assessments in Gammaridae.
اظهر المزيد [+] اقل [-]Ecotoxicological survey of MNEI and Y65R-MNEI proteins as new potential high-intensity sweeteners النص الكامل
2017
Rega, Michele Fortunato | Siciliano, Antonietta | Gesuele, Renato | Lofrano, Giusy | Carpentieri, Andrea | Picone, Delia | Guida, Marco
Low-calorie sweeteners are widespread. They are routinely introduced into commonly consumed food such as diet sodas, cereals, and sugar-free desserts. Recent data revealed the presence in considerable quantities of some of these artificial sweeteners in water samples qualifying them as a class of potential new emerging contaminants. This study aimed at evaluating the ecotoxicity profile of MNEI and Y65R-MNEI, two engineered products derived from the natural protein monellin, employing representative test organism such as Daphnia magna, Ceriodaphnia dubia, and Raphidocelis subcapitata. Potential genotoxicity and mutagenicity effects on Salmonella typhimurium (strain TA97a, TA98, TA100, and TA1535) and Escherichia coli (strain WP2 pkM101) were evaluated. No genotoxicity effects were detected, whereas slight mutagenicity was highlighted by TA98 S. typhimurium. Ecotoxicity results evidenced effects approximately up to 14 and 20% with microalgae at 500 mg/L of MNEI and Y65R-MNEI, in that order. Macrophytes and crustaceans showed no significant effects. No median effective concentrations were determined. Overall, MNEI and Y65R-MNEI can be classified as not acutely toxic for the environment.
اظهر المزيد [+] اقل [-]The use of bacterial bioremediation of metals in aquatic environments in the twenty-first century: a systematic review النص الكامل
2017
de Alencar, Feliphe Lacerda Souza | Navoni, Julio Alejandro | do Amaral, Viviane Souza
Metal pollution is a current environmental issue as a consequence of unregulated anthropic activiy. A wide range of bioremediation strategies have been successfully implemented to recover contaminated areas. Among them, bacterial bioremediation stands out as a promising tool to confront these types of concerns. This study aimed to compare and discuss worldwide scientific evolution of bacterial potential for metal bioremediation in aquatic ecosystems. The study consisted of a systematic review, elaborated through a conceptual hypothesis model, during the period from 2000 to 2016, using PubMed, MEDLINE, and SciELO databases as data resources. The countries with the largest number of reports included in this work were India and the USA. Industrial wastewater discharge was the main subject associated to metal contamination/pollution and where bacterial bioremediations have mostly been applied. Biosorption is the main bioremediation mechanism described. Bacterial adaptation to metal presence was discussed in all the selected studies, and chromium was the most researched bioremedied substrate. Gram-negative Pseudomonas aeruginosas and the Gram-positive Bacillus subtilis bacteria were microorganisms with the greatest applicability for metal bioremediation. Most reports involved the study of genes and/or proteins related to metal metabolism and/or resistence, and Chromobacterium violaceum was the most studied. The present work shows the relevance of metal bacterial bioremediation through the high number of studies aimed at understanding the microbiological mechanisms involved. Moreover, the developed processes applied in removal and/or reducing the resulting environmental metal contaminant/pollutant load have become a current and increasingly biotechnological issue for recovering impacted areas.
اظهر المزيد [+] اقل [-]Impact of metal stress on the production of secondary metabolites in Pteris vittata L. and associated rhizosphere bacterial communities النص الكامل
2017
Phạm, Hoàng Nam | Michalet, Serge | Bodillis, Josselin | Nguyễn, Tiến Đạt | Nguyen, Thi Kieu Oanh | Le, Thi Phuong Quynh | Haddad, Mohamed | Nazaret, Sylvie | Dijoux-Franca, Marie-Geneviève
Impact of metal stress on the production of secondary metabolites in Pteris vittata L. and associated rhizosphere bacterial communities النص الكامل
2017
Phạm, Hoàng Nam | Michalet, Serge | Bodillis, Josselin | Nguyễn, Tiến Đạt | Nguyen, Thi Kieu Oanh | Le, Thi Phuong Quynh | Haddad, Mohamed | Nazaret, Sylvie | Dijoux-Franca, Marie-Geneviève
Plants adapt to metal stress by modifying their metabolism including the production of secondary metabolites in plant tissues. Such changes may impact the diversity and functions of plant associated microbial communities. Our study aimed to evaluate the influence of metals on the secondary metabolism of plants and the indirect impact on rhizosphere bacterial communities. We then compared the secondary metabolites of the hyperaccumulator Pteris vittata L. collected from a contaminated mining site to a non-contaminated site in Vietnam and identified the discriminant metabolites. Our data showed a significant increase in chlorogenic acid derivatives and A-type procyanidin in plant roots at the contaminated site. We hypothesized that the intensive production of these compounds could be part of the antioxidant defense mechanism in response to metals. In parallel, the structure and diversity of bulk soil and rhizosphere communities was studied using high-throughput sequencing. The results showed strong differences in bacterial composition, characterized by the dominance of Proteobacteria and Nitrospira in the contaminated bulk soil, and the enrichment of some potential human pathogens, i.e., Acinetobacter, Mycobacterium, and Cupriavidus in P. vittata’s rhizosphere at the mining site. Overall, metal pollution modified the production of P. vittata secondary metabolites and altered the diversity and structure of bacterial communities. Further investigations are needed to understand whether the plant recruits specific bacteria to adapt to metal stress.
اظهر المزيد [+] اقل [-]Impact of metal stress on the production of secondary metabolites in Pteris vittata L. and associated rhizospherebacterial communities النص الكامل
2017
Pham, Hoang Nam | Michalet, Serge | Bodilis, Josselin | Nguyen, Tien Dat | Nguyen, Thi Kieu Oanh | Le, Thi Phuong Quynh | Haddad, Mohamed | Nazaret, Sylvie | Dijoux-Franca, Marie-Geneviève | Vietnam Academy of Science and Technology (VAST) | Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM) ; Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM) ; Université de Rouen Normandie (UNIROUEN) ; Normandie Université (NU)-Normandie Université (NU) | PMAB Department ; University of Science and Technology of Hanoi (USTH) | Pharmacochimie et Biologie pour le Développement (PHARMA-DEV) ; Institut de Recherche pour le Développement (IRD)-Institut de Chimie de Toulouse (ICT) ; Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT) | UMR 5557 CNRS Microbial Ecology; Vietnam Ministry of Education and Training; University of Sciences and Technologies of Hanoi; "Environmental resistance and bacterial efflux"
International audience | Plants adapt to metal stress by modifying their metabolism including the production of secondary metabolites in plant tissues. Such changes may impact the diversity and functions of plant associated microbial communities. Our study aimed to evaluate the influence of metals on the secondary metabolism of plants and the indirect impact on rhizosphere bacterial communities. We then compared the secondary metabolites of the hyperaccumulator Pteris vittata L. collected from a contaminated mining site to a non-contaminated site in Vietnam and identified the discriminant metabolites. Our data showed a significant increase in chlorogenic acid derivatives and A-type procyanidin in plant roots at the contaminated site. We hypothesized that the intensive production of these compounds could be part of the antioxidant defense mechanism in response to metals. In parallel, the structure and diversity of bulk soil and rhizosphere communities was studied using high-throughput sequencing. The results showed strong differences in bacterial composition, characterized by the dominance of Proteobacteria and Nitrospira in the contaminated bulk soil, and the enrichment of some potential human pathogens, i.e., Acinetobacter, Mycobacterium, and Cupriavidus in P. vittata's rhizosphere at the mining site. Overall, metal pollution modified the production of P. vittata secondary metabolites and altered the diversity and structure of bacterial communities. Further investigations are needed to understand whether the plant recruits specific bacteria to adapt to metal stress.
اظهر المزيد [+] اقل [-]Removal of antibiotic cloxacillin by means of electrochemical oxidation, TiO2 photocatalysis, and photo-Fenton processes: analysis of degradation pathways and effect of the water matrix on the elimination of antimicrobial activity النص الكامل
2017
Serna-Galvis, Efraim A. | Giraldo-Aguirre, Ana L. | Silva-Agredo, Javier | Flórez-Acosta, Oscar A. | Torres-Palma, Ricardo A.
This study evaluates the treatment of the antibiotic cloxacillin (CLX) in water by means of electrochemical oxidation, TiO₂ photocatalysis, and the photo-Fenton system. The three treatments completely removed cloxacillin and eliminated the residual antimicrobial activity from synthetic pharmaceutical wastewater containing the antibiotic, commercial excipients, and inorganic ions. However, significant differences in the degradation routes were found. In the photo-Fenton process, the hydroxyl radical was involved in the antibiotic removal, while in the TiO₂ photocatalysis process, the action of both the holes and the adsorbed hydroxyl radicals degraded the pollutant. In the electrochemical treatment (using a Ti/IrO₂ anode in sodium chloride as supporting electrolyte), oxidation via HClO played the main role in the removal of CLX. The analysis of initial by-products showed five different mechanistic pathways: oxidation of the thioether group, opening of the central β-lactam ring, breakdown of the secondary amide, hydroxylation of the aromatic ring, and decarboxylation. All the oxidation processes exhibited the three first pathways. Moreover, the aromatic ring hydroxylation was found in both photochemical treatments, while the decarboxylation of the pollutant was only observed in the TiO₂ photocatalysis process. As a consequence of the degradation routes and mechanistic pathways, the elimination of organic carbon was different. After 480 and 240 min, the TiO₂ photocatalysis and photo-Fenton processes achieved ∼45 and ∼15 % of mineralization, respectively. During the electrochemical treatment, 100 % of the organic carbon remained even after the antibiotic was treated four times the time needed to degrade it. In contrast, in all processes, a natural matrix (mineral water) did not considerably inhibit pollutant elimination. However, the presence of glucose in the water significantly affected the degradation of CLX by means of TiO₂ photocatalysis.
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