خيارات البحث
النتائج 2291 - 2300 من 4,294
Preparation of magnetic MIL-101 (Cr) for efficient removal of ciprofloxacin
2017
Bayazit, Şahika Sena | Danalıoğlu, Selen Tuğba | Abdel Salam, Mohamed | Kerkez Kuyumcu, Özge
Metal organic frameworks are widely used as adsorbent materials in recent years. In this study, the most prepared metal organic framework MIL-101 was prepared by hydrothermal method and featured magnetic property using co-precipitation method Fe₃O₄. Then, the prepared composite (MIL-101/Fe₃O₄) was first characterized using XRD, FTIR, SEM-EDS, and surface area analysis, then was used for the adsorptive removal of the most used antibiotic, ciprofloxacin (CIP). The effect of different adsorption variables which may affect the removal of CIP by MIL-101/Fe₃O₄ was investigated, as well as their adsorbent quantity, initial CIP concentration, pH, temperature, and contact time. The non-linear Langmuir and Freundlich isotherm were applied to experimental data. It was observed that rising solution temperature decreases adsorption efficiency, as the maximum adsorption uptake value was 63.28 mg g⁻¹ at 298 K and 22.93 mg g⁻¹ at 313 K, indicating the exothermic nature of the adsorption. The adsorption was studied kinetically and found to follow the pseudo-second-order kinetic model. The desorption of CIP from the MIL-101/Fe₃O₄ was investigated using three different eluents, and the results showed that phosphate-buffered solution was the most effective desorption eluent. Graphical abstract Schematic diagram of the preparation steps of MIL-101/Fe3O4
اظهر المزيد [+] اقل [-]Integrated monitoring for environmental health impact assessment related to the genotoxic effects of vehicular pollution in Uberlândia, Brazil
2017
Pereira, Boscolli Barbosa | da Cunha, Paolla Brandão | Silva, Guilherme Gomes | de Campos Júnior, Edimar Olegário | Morelli, Sandra | Filho, Cláudio Alves Vieira | de Lima, Euclides Antônio Pereira | Barrozo, Marcos Antônio Souza
The development of parameters to explore the link between air-related diseases and their significant driving forces is an important aim in terms of national economics and public health. In this study, we did an integrated analysis involving multiple environmental health indicators from Uberlândia, Brazil, registered before and during a period when the Brazilian government reduced taxes on new cars in a bid to bolster local manufacturing. In addition, the present study utilized Driving Force-Pressure-State-Exposure-Effect-Action (DPSEEA) frameworks to evaluate correlations in environmental health indicators over 10 years (2004–2013), in which the Brazilian government reduced vehicle production taxes beginning in 2008. Significant correlations in all indicators selected were found from 2008 to 2013, corresponding to the tax reduction on new vehicles. The frequency of micronuclei (MN) was significantly higher in the city center compared to the reference site, with the highest MN levels observed during the period of reduced taxes. Results reinforced the need to adopt air quality monitoring programs in major cities.
اظهر المزيد [+] اقل [-]Effects of Praxelis clematidea invasion on soil nitrogen fractions and transformation rates in a tropical savanna
2017
Wei, Hui | Xu, Jialin | Quan, Guoming | Zhang, Jiaen | Qin, Zhong
Plant invasion has been reported to affect a mass of soil ecological processes and functions, although invasion effects are often context-, species- and ecosystem- specific. This study was conducted to explore potential impacts of Praxelis clematidea invasion on contents of total and available soil nitrogen (N) and microbial N transformations in a tropical savanna. Soil samples were collected from the surface and sub-surface layers in plots with non-, slight, or severe P. clematidea invasion in Hainan Province of southern China, which remains less studied, and analyzed for contents of the total and available N fractions and microbial N transformations. Results showed that total N content significantly increased in the surface soil but trended to decrease in the sub-surface soil in the invaded plots relative to the non-invaded control. Slight invasion significantly increased soil alkali-hydrolysable N content in the two soil layers. Soil net N mineralization rate was not significantly changed in both the soil layers, although soil microbial biomass N was significantly higher in plots with severe invasion than the control. There was no significant difference in content of soil N fractions between plots with slight and severe invasion. Our results suggest that invasion of P. clematidea promotes soil N accumulation in the surface soil layer, which is associated with increased microbial biomass N. However, the invasion-induced ecological impacts did not increase with further invasion. Significantly higher microbial biomass N was maintained in plots with severe invasion, implying that severe P. clematidea invasion may accelerate nutrient cycling in invaded ecosystems.
اظهر المزيد [+] اقل [-]Toxicity evaluation of vinasse and biosolid samples in diplopod midgut: heat shock protein in situ localization
2017
Coelho, Maria Paula Mancini | Moreira-de-Sousa, Cristina | de Souza, Raphael Bastão | Ansoar-Rodríguez, Yadira | Silva-Zacarin, Elaine Cristina Mathias | Fontanetti, Carmem Silvia
Large amounts of residues generated by agricultural, urban and industrial activities are dumped daily on the soil. This practice deserves special attention because it causes serious environmental problems. This study evaluated the toxic potential of the sugarcane vinasse, a by-product of the sugar-alcohol industry, and the biosolid, a residue produced by wastewater treatment plants, both widely used as fertilizers. The evaluation was performed through bioassays using a typical soil bioindicator, the diplopod Rhinocricus padbergi. The specimens were exposed to soils containing these residues in concentrations that are compatible with the Brazilian regulation for agricultural use. Semi-quantitative immunolabelling analyses of the stress protein HSP70 were performed on the midgut of the studied diplopods. There was a significant increase in the immunolabelling of HSP70 proteins as a response to xenobiotics from both residues, particularly in regions where the function of the cells is the detoxification of the organ (e.g. the hepatic cell layer and specific regions of the epithelium). Higher immunolabelling was observed in the specimens exposed to vinasse in comparison with the biosolid exposure. This demonstrates that the substances in the tested residues had proteotoxic action in the exposed animals and induced a cytoprotective response, which led to higher stress protein immunolabelling. Therefore, caution is needed for the use of such residues in agriculture.
اظهر المزيد [+] اقل [-]Long-term spatiotemporal trends and health risk assessment of oyster arsenic levels in coastal waters of northern South China Sea
2017
Wang, Xuefeng | Wang, Lifei | Jia, Xiaoping | Jackson, Donald A.
Long-term spatiotemporal trends and health risk assessment of oyster arsenic levels in the coastal waters of northern South China Sea were investigated in order to help improve the quality and safety control and sustainable aquaculture for mollusks in China. Cultured oysters (Crassostrea rivularis) collected from the waters of 23 bays, harbors, and estuaries along the coast of northern South China Sea from 1989 to 2012 were examined for spatial patterns and long-term temporal trends of oyster arsenic levels. Single-factor index and health risk assessment were used to quantify arsenic exposure to human health through oyster consumption. Overall, arsenic was detected in 97.4% of the oyster samples, and oyster arsenic levels were non-detectable—2.51 mg/kg with an average of 0.63 ± 0.54 mg/kg. Oyster arsenic levels in the coastal waters of northern South China Sea showed an overall decline from 1989 to 2012, remained relatively low since 2005, and slightly increased after 2007. Oyster arsenic levels in Guangdong coastal waters were much higher with more variation than in Guangxi and Hainan coastal waters, and the long-term trends of oyster arsenic levels in Guangdong coastal waters dominated the overall trends of oyster arsenic levels in the coastal waters of northern South China Sea. Within Guangdong Province, oyster arsenic levels were highest in east Guangdong coastal waters, followed by the Pearl River estuary and west Guangdong coastal waters. Single-factor index ranged between 0.27 and 0.97, and average health risk coefficient was 3.85 × 10⁻⁵, both suggesting that oyster arsenic levels in northern South China Sea are within the safe range for human consumption. However, long-term attention should be given to seafood market monitoring in China and the risk of arsenic exposure to human health through oyster consumption.
اظهر المزيد [+] اقل [-]Kinetics of 210Po accumulation in moss body profiles
2017
Długosz-Lisiecka, Magdalena
Radionuclide concentration analysis of total moss bodies often gave relatively different results than a separate analysis of each different morphological part of the same sample. The dynamics of the transfer of metals by dust uplifted from the soil and another approach, based on the diffusion of the two radionuclides to the moss, have been analyzed. In the proposed model, short- and long-term approaches have been applied. Each part of a moss’s profile can show different radionuclides accumulation ability, including both ²¹⁰Pb and ²¹⁰Po isotopes. A first-order kinetic model has been used for ²¹⁰Po and ²¹⁰Pb transport between three body components of mosses. This mathematical approach has been applied for ²¹⁰Po activity concentration in the air estimation. For relatively clean deep forest region, calculated concentrations were from 17.2 to 43.8 μBqm⁻³, while for urban air concentrations were higher from 49.1 to 104.9 μBqm⁻³.
اظهر المزيد [+] اقل [-]Immune competence assessment in marine medaka (Orzyias melastigma)—a holistic approach for immunotoxicology
2017
Ye, Roy R. | Peterson, Drew R. | Seemann, Frauke | Kitamura, Shin-Ichi | Lee, J. S. | Lau, Terrance C. K. | Tsui, Stephen K. W. | Au, Doris W. T.
Many anthropogenic pollutants in coastal marine environments can induce immune impairments in wild fish and reduce their survival fitness. There is a pressing need to establish sensitive and high throughput in vivo tools to systematically evaluate the immunosuppressive effects of contaminants in marine teleosts. This study reviewed a battery of in vivo immune function detection technologies established for different biological hierarchies at molecular (immune function pathways and genes by next generation sequencing (NGS)), cellular (leukocytes profiles by flow cytometry), tissues/organ system (whole adult histo-array), and organism (host resistance assays (HRAs)) levels, to assess the immune competence of marine medaka Oryzias melastigma. This approach enables a holistic assessment of fish immune competence under different chemical exposure or environmental scenarios. The data obtained will also be useful to unravel the underlying immunotoxic mechanisms. Intriguingly, NGS analysis of hepatic immune gene expression profiles (male > female) are in support of the bacterial HRA findings, in which infection-induced mortality was consistently higher in females than in males. As such, reproductive stages and gender-specific responses must be taken into consideration when assessing the risk of immunotoxicants in the aquatic environment. The distinct phenotypic sexual dimorphism and short generation time (3 months) of marine medaka offer additional advantages for sex-related immunotoxicological investigation.
اظهر المزيد [+] اقل [-]A multivariate approach for a comparison of big data matrices. Case study: thermo-hygrometric monitoring inside the Carcer Tullianum (Rome) in the absence and in the presence of visitors
2017
Visco, Giovanni | Plattner, Susanne H. | Fortini, Patrizia | Sammartino, Mariapia
In the last decades, the very fast improvement of the analytical instrumentation has led to the possibility of quickly and easily getting a lot of data; in turn, the need of advanced statistical methods suitable to extract the full information furnished by instruments has increased. Such kind of data treatments is particularly important in any case of continuous monitoring of one or more parameters, so the microclimate monitoring is a typical example for this application. Microclimate control is essential in the conservation of Cultural Heritage (CH), but decisions on optimal conservation parameters cannot base only on existing norms that do not take into account the environment’s history. Often CH has survived for many centuries in conditions that must be considered risky but also a stable state (equilibrium) resulting from a long adaptation process during which a more or less heavy damage occurred to the materials. Any successive change of microclimate parameters has interrupted this equilibrium conditions and has induced further damage to material until a new equilibrium is reached; dimension and frequency of changes are proportional to the expected damage. This thermodynamic consideration provides the background for a CH conservation project based on microclimate control and highlights the importance of environmental monitoring for the identification of equilibrium parameters to be maintained. In 2010, we monitored the microclimate of an important historical building in Rome, the Mamertino Carcer, before its opening to visitors. One year later, we repeated the monitoring in the presence of visitors, and here, we present a careful choice of multivariate data treatments adopted for an enough, simple and immediate evaluation of the microclimatic changes; this allows an easier understanding also for persons with not too deep scientific background, such as Superintendents and, in turn, really useful information to provide suggestions for a conservation project. Results evidenced the expected loss of isolation of the site that occurred by opening to visitors; this led to wider excursions of both temperature and relative humidity and, in turn, to a worsening of the conservative conditions. Surely, a monitoring of particulate matter, correlated to air fluxes and, in turn, to microclimate, is of fundamental importance for the conservation of frescoes and will be object of one of our future diagnostic interventions in the site.
اظهر المزيد [+] اقل [-]Response of low-molecular-weight organic acids in mangrove root exudates to exposure of polycyclic aromatic hydrocarbons
2017
Jiang, Shan | Xie, Feng | Lu, Haoliang | Liu, Jingchun | Yan, Chongling
Low-molecular-weight organic acids (LMWOAs) represent an important component of root exudates. They play a pivotal role in the degradation of polycyclic aromatic hydrocarbons (PAHs) in sediments as they influence PAH bioavailability and degrader colonization. This study examined variations of LMWOAs in mangrove root exudates (Aegiceras corniculatum and Kandelia obovata) after exposure in phenanthrene and pyrene solution for 7 and 40 days, respectively. After 7 days of treatment, total root exudates and six types of LMWOA in root exudates from both mangrove species were enhanced. The largest increase was found in oxalic acid, i.e., the dominant component in determined LMWOAs. Coupled with the enhancement in LMWOA exudation rates, root metabolism intensities, measured as the dehydrogenase activity, increased. In contrast, after 40 days of exposure, the exudation rate of total LMWOAs had dropped markedly in PAH-contaminated groups compared to the control, indicating that PAHs negatively impacted root metabolism and activities due to their toxicity. The largest decrease was also found in oxalic acid, suggesting that the biological reactions related with oxalic acid are vulnerable under PAH stresses.
اظهر المزيد [+] اقل [-]Enhancing anti-microbial properties of wood-plastic composites produced from timber and plastic wastes
2017
Wang, Lei | Chen, Season S. | Tsang, Daniel C. W. | Poon, C. S. (Chi-sun) | Ok, Yong Sik
Considering the resource waste and environmental burden for timber and plastic materials ending up at landfills, this study proposed upcycling wood and plastic waste into value-added wood-plastic composites (WPCs), complying with the standard requirements of flexural strength, thickness swelling, water absorption and thermal insulation. Biological deterioration is a major concern of WPCs. Bacterial survival, fungal attack and algal growth of bactericide-treated WPCs were holistically analysed. Melamine resin was adopted for impregnating anti-microbial agents on the surface. All the agents showed excellent bactericidal rate (Escherichia coli), yet poly-diallyl-dimethyl-ammonium chloride (PolyDADMAC) and silver had the lowest minimum inhibitory concentrations. In terms of weight loss and strength reduction due to fungal decay (Coriolus versicolor), PolyDADMAC, silver and cetyltrimethylammonium bromide (CTAB) imparted the highest resistance on the WPCs. Moreover, PolyDADMAC and copper provided the most protection against algal growth (Chlorella vulgaris), and the former presented durable inhibitory effect. This study presents a value-added solution to wood/plastic waste recycling.
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