خيارات البحث
النتائج 4131 - 4140 من 4,937
The effect of ambient air pollution on circulatory mortality: a short-term exposure assessment in Xi’an, China النص الكامل
2019
Mokoena, Kingsley Katleho | Ethan, Crystal Jane | Yu, Yan | Shale, Karabo | Fan, Yameng | Liu, Feng | Rong, Jie
Various studies have illustrated that exposure to ambient air pollution has negative impacts on health. However, little evidence exists on the effects of ambient air pollution on circulatory mortality in Xi’an, China. This study aims to investigate and ascertain the association between short-term exposure to ambient air pollutants and circulatory mortality in Xi’an, China. Daily average concentrations of PM₂.₅, SO₂, and O₃, meteorological data (temperature and relative humidity) and daily counts of circulatory mortality were obtained between January 2014 and June 2016. Mortality was stratified by gender and age group (≤ 64 years and ≥ 65 years). A generalized additive model (GAM) with natural splines (NS) was constructed to analyze the relationship between ambient air pollutants and daily circulatory mortality. There were 57,570 cases of circulatory mortality, with cerebrovascular and ischemic heart diseases accounting for 48.5% and 43.5%, respectively. All ambient air pollutants displayed different seasonal patterns. In the single pollutant model, 10 μg/m³ increase in 2-day moving average concentrations of PM₂.₅, SO₂, and O₃ was associated with relative risk of 1.288(1.198, 1.388), 1.360(0.877, 2.331), and 1.324(1.059, 1.705) in circulatory mortality, respectively. After adjusting for collinearity in the multi-pollutant model, the effects remained statistically significant. The ≥ 65 years and female sub-groups were associated with a higher risk of circulatory mortality. Short-term exposure to ambient air pollutants plays a pivotal role in the genesis of circulatory mortality in Xi’an. Responses to ambient air pollutants exposure in relation to circulatory mortality are different when analyzed by sub-groups.
اظهر المزيد [+] اقل [-]Protective effects of zingerone on cisplatin-induced nephrotoxicity in female rats النص الكامل
2019
Kandemir, Fatih Mehmet | Yildirim, Serkan | Caglayan, Cuneyt | Kucukler, Sefa | Eser, Gizem
Zingerone (ZO), one of the active components of ginger (Zingiber officinale), is a phenolic alkanone with antioxidant, antiapoptotic, and anti-inflammatory properties. Cisplatin (CP) is a widely used chemotherapeutic drug for solid tumors, but its therapeutic use is limited due to dose-dependent nephrotoxicity. In the present study, we investigated the ameliorative effect of ZO against CP-induced nephrotoxicity. Intraperitoneal administration of single-dose CP (7 mg/kg body weight) on the first day enhanced kidney lipid peroxidation and reduced antioxidant enzyme activities such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH). CP increased serum urea and creatinine levels and disrupted histological integrity while causing a decrease aquaporin 1 (AQP1) level in the kidney tissues. CP induced inflammatory responses by elevating the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-33 (IL-33) and nuclear factor kappa B (NF-κB), and activities of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, it also caused oxidative DNA damage and activation of apoptotic pathway by increasing of 8-hydroxy-2′-deoxyguanosine (8-OHdG), p53, cysteine aspartate-specific protease-3 (caspase-3), and Bcl-2-associated x protein (bax) while decreasing B cell lymphoma-2 (Bcl-2). However, treatment with ZO at a dose of 25 and 50 mg/kg b.wt. for 7 days significantly decreased oxidative stress, apoptosis, inflammation, and histopathological alterations while increased AQP1 levels in the kidney tissue. The results of the current study suggested that ZO as an effective natural product attenuates CP-induced nephrotoxicity.
اظهر المزيد [+] اقل [-]Chitosan cross-linked with κ-carrageenan to remove cadmium from water and soil systems النص الكامل
2019
Mola Ali Abasiyan, Sara | Dashbolaghi, Farahnaz | Mahdavinia, Gholam Reza
In this study, magnetic bio-adsorbent based on chitosan with high molecular weight was prepared. To stabilize under acidic condition, the synthesized magnetic chitosan was cross-linked with κ-carrageenan (mChitoCar). The magnetic bio-adsorbent was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicated that mChitoCar had desirable magnetic-sorption properties, and magnetic/bio-adsorbent was successfully synthesized and cross-linked. The present nanocomposite was applied to remove and immobilize Cd²⁺ from water and soil systems. Adsorption and desorption of cadmium by the chitosan bio-adsorbent were investigated using batch experiments. Isotherm data were described by using Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin models, and better fitting was introduced by Freundlich model in both water and soil systems. The maximum adsorption capacity (b) of cadmium onto mChitoCar appeared to increase from the water system to the soil system, from 750.2 to 992.7 μmol/g, respectively. The adsorption mechanism with the help of potential theory indicates the adsorption of cadmium onto the mChitoCar surface is following chemical adsorption type. To evaluate the efficiency of the modified chitosan as a good bio-adsorbent in water and soil system, the difference between adsorption and desorption amounts, Δq, was calculated. By comparing the amounts of Δq, the bio-adsorbent is not economically feasible at high initial concentrations in the water system. But, the bio-adsorbent used can be relatively economic as a soil modifier.
اظهر المزيد [+] اقل [-]The effect of carbon dioxide emission and the consumption of electrical energy, fossil fuel energy, and renewable energy, on economic performance: evidence from Pakistan النص الكامل
2019
Rehman, Abdul | Rauf, Abdul | Ahmad, Munir | Chandio, Abbas Ali | Deyuan, Zhang
Energy affects the economic growth and development of a country. Renewable energy has become an important part of the world’s energy consumption. The use of fossil fuel energy contributes to global warming and carbon dioxide emissions, and has a detrimental effect on the environment. The long-run and short-run causality relationships between electric power consumption, renewable electricity output, renewable energy consumption, fossil fuel energy consumption, energy use, carbon dioxide emissions, and gross domestic product per capita for Pakistan over the period of 1990–2017 were investigated in this paper using the autoregressive distributed lag bounds testing approach to cointegration. The augmented Dickey–Fuller unit root test and the Phillips–Perron unit root test were used to check the stationarity of the variables, while the Johansen cointegration test was applied to check the robustness of the long-run relationships. The Granger causality test under the vector error correction model extracted during the short-run estimation showed a unidirectional relationship among all variables except for the relationship between gross domestic product per capita and carbon dioxide emission, which was bidirectional (feedback hypothesis). The evidence showed that in the long run, carbon dioxide emissions, electric power consumption, and renewable electricity output had a positive and significant relationship with the gross domestic product per capita, while the relationship of renewable energy consumption, energy use, and fossil fuel energy consumption with the gross domestic product per capita had a negative effect. Overall, the long-run effects of the variables were found to have a stronger effect on the gross domestic product per capita than the short-run dynamics, which indicated that the findings were heterogeneous. The evidence suggests that the government of Pakistan should take steps to enhance the use of renewable energy resources to resolve the energy crisis in the country and introduce new policies to reduce carbon dioxide emissions.
اظهر المزيد [+] اقل [-]Organic carbon content and humus composition after application aluminum sulfate and rice straw to soda saline-alkaline soil النص الكامل
2019
Zhao, Xingmin | Zhu, Menglong | Guo, Xinxin | Wang, Hongbin | Sui, Biao | Zhao, Lanpo
The soil organic carbon accumulation in soda saline-alkaline soil and the humus composition changes with application of aluminum sulfate and rice straw were investigated by the controlled simulative experiments in laboratory. For evaluating the amelioration effect, organic carbon content and humus composition in soda saline-alkaline soil were investigated with different application amounts of rice straw and aluminum sulfate. Potassium dichromate oxidation titration (exogenous heat) method and Kumada method were used to analyze the contents of organic carbon and humus composition, respectively. The transformation of soil organic matter in the saline-alkali soil during the amelioration has been clarified in this paper. The results demonstrated that the contents of soil organic carbon were significantly increased (13–92%) with different application amounts of rice straw and aluminum sulfate. The contents of free fraction and combined fraction of humus and their compositions (humic acid and fulvic acid) were increased with different application amounts of rice straw. The free fraction of humus was increased more dramatically. Due to aluminum sulfate application, free fraction of humus and humic acid (HA) was transformed to combined fraction partially. Free HA was changed to be P type with rice straw application. With aluminum sulfate application, free form of HA was changed from type P to type Rp. For rice straw application, combined HA only was transferred within the area of type A. Aluminum sulfate addition had no significant effect on the type of combined form of HA. With the same amount of rice straw application, the contents of soil organic carbon were increased by increasing the amount of aluminum sulfate application. Both rice straw and aluminum sulfate applications could reduce the humification degree of free and combined fraction of HA. According to the types of HA, it could be concluded that humus became younger and renewed due to the application of rice straw and aluminum sulfate.
اظهر المزيد [+] اقل [-]Effect of pH and polypropylene beads in hybrid water treatment process of alumina ceramic microfiltration and PP beads with air back-flushing and UV irradiation النص الكامل
2019
Park, Jin Yong | Song, Seunghwa
For advanced water treatment, effects of pH and pure polypropylene (PP) beads packing concentration on membrane fouling and treatment efficiency were observed in a hybrid process of alumina ceramic microfiltration (MF; pore size 0.1 μm) and pure PP beads. Instead of natural organic matters and fine inorganic particles in natural water source, a quantity of humic acid (HA) and kaolin was dissolved in distilled water. The synthetic feed flowed inside the MF membrane, and the permeated water contacted the PP beads fluidized in the gap of the membrane and the acryl module case with outside UV irradiation. Periodic air back-flushing was performed to control membrane fouling during 10 s per 10 min. The membrane fouling resistance (Rf) was the maximum at 30 g/L of PP bead concentration. Finally, the maximum total permeated volume (VT) was acquired at 5 g/L of PP beads, because flux maintained higher all through the operation. The treatment efficiency of turbidity was almost constant, independent of PP bead concentration; however, that of dissolved organic materials (DOM) showed the maximal at 50 g/L of PP beads. The Rf increased as increasing feed pH from 5 to 9; however, the maximum VT was acquired at pH 6. It means that the membrane fouling could be inhibited at low acid condition. The treatment efficiency of turbidity increased a little, and that of DOM increased from 73.6 to 75.7% as increasing pH from 5 to 9.
اظهر المزيد [+] اقل [-]Study of polyamide thin film characteristics impact on permeability/selectivity performance and fouling behavior of forward osmosis membrane النص الكامل
2019
Rastgar, Masoud | Shakeri, Alireza | Ṣāliḥī, Ḥasan
In recent years, forward osmosis (FO) has received considerable attention due to its huge potentials in water desalination. The thin film composite (TFC) membrane used in the FO desalination consists of a bottom support layer covered by an active layer on top. Polyamide (PA) is commonly employed as an active layer forming via interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers. In this study, the effects that the MPD and TMC concentrations could have on the performance and anti-fouling behavior of the obtained FO membrane have been investigated. Results showed that there is a trade-off relationship between the water flux and salt rejection, which by increasing MPD concentration, the water flux was reducedو while the salt rejection was enhanced. Also, by increasing the TMC concentration, an opposite trend was observed. Using 0.20 wt.% of TMC monomer, the highest water fluxes of 21.6 LMH and 29.3 LMH were achieved in two different membrane configurations. Furthermore, higher TMC concentration caused better anti-fouling property, when PA active layer of the membrane was in a high fouling potential environment.
اظهر المزيد [+] اقل [-]Do agricultural activities induce carbon emissions? The BRICS experience النص الكامل
2019
Balsalobre-Lorente, Daniel | Driha, Oana M. | Bekun, Festus Victor | Osundina, Olawumi Abeni
Do agricultural activities induce carbon emissions? The BRICS experience النص الكامل
2019
Balsalobre-Lorente, Daniel | Driha, Oana M. | Bekun, Festus Victor | Osundina, Olawumi Abeni
This study investigates the environmental Kuznets curve (EKC) hypothesis for Brazil, Russia, India, China and South Africa (BRICS) over the period 1990–2014, while considering agricultural activities, energy use, trade openness and mobile use as driving forces of environmental degradation. The empirical results verify an inverted U-shaped connection between carbon emissions and economic growth. This study confirms the unfriendly impact of agriculture on the environment. Electricity consumption and trade openness likewise exhibit similar impacts on carbon emissions. Mobile use however reduces pollution. A unique revelation from this study is that the interaction between electricity consumption and agricultural activities has an additional pernicious effect on the environment. The methodologies applied for testing the impact of selected independent variables on carbon emissions in BRICS are the Dynamic Ordinary Least Squares (DOLS) and the Fully Modify Ordinary Least Square (FMOLS) for long run regression. Empirical evidence confirms that agriculture exerts a negative impact on the environment in BRICS countries. This study therefore recommends the adoption of cleaner energy processes and enabling high-tech and clean foreign investment.
اظهر المزيد [+] اقل [-]Do agricultural activities induce carbon emissions? The BRICS experience النص الكامل
2019
Balsalobre-Lorente, Daniel | Driha, Oana M. | Bekun, Festus Victor | Osundina, Olawumi Abeni | Universidad de Alicante. Departamento de Análisis Económico Aplicado | Universidad de Alicante. Instituto Interuniversitario de Economía Internacional | Economía del Turismo, Recursos Naturales y Nuevas Tecnologías (INNATUR)
This study investigates the environmental Kuznets curve (EKC) hypothesis for Brazil, Russia, India, China and South Africa (BRICS) over the period 1990–2014, while considering agricultural activities, energy use, trade openness and mobile use as driving forces of environmental degradation. The empirical results verify an inverted U-shaped connection between carbon emissions and economic growth. This study confirms the unfriendly impact of agriculture on the environment. Electricity consumption and trade openness likewise exhibit similar impacts on carbon emissions. Mobile use however reduces pollution. A unique revelation from this study is that the interaction between electricity consumption and agricultural activities has an additional pernicious effect on the environment. The methodologies applied for testing the impact of selected independent variables on carbon emissions in BRICS are the Dynamic Ordinary Least Squares (DOLS) and the Fully Modify Ordinary Least Square (FMOLS) for long run regression. Empirical evidence confirms that agriculture exerts a negative impact on the environment in BRICS countries. This study therefore recommends the adoption of cleaner energy processes and enabling high-tech and clean foreign investment.
اظهر المزيد [+] اقل [-]An overview of heavy metal pollution in Chaohu Lake, China: enrichment, distribution, speciation, and associated risk under natural and anthropogenic changes النص الكامل
2019
Fang, Ding | Yang, Kun | Lu, Wenxuan | Cui, Kai | Li, Jing | Liang, Yangyang | Hou, Guanjun | Zhao, Xiuxia | Li, Hui
An exhaustive overview of heavy metal pollution in Chaohu Lake illustrating enrichment intensity, temporal and spatial distribution, chemical speciation, and ecological risk under natural and anthropogenic changes was conducted. Low concentrations of heavy metals excluding Hg were found in water whereas high Hg might be ascribed to surrounding coal-fired power plants. Copper, Pb, Zn, Cd, and Hg were enriched in sediment whereas Cr and Ni were comparable to background values. Besides, As demonstrated an equal accumulation from natural and anthropogenic fluxes. Heavy metals were at a low level prior to the 1950s; it increased gradually during the 1950s–1960s owing to population growth and agricultural expansion; then it displayed abrupt increase since the late 1970s due to rapid modern urbanization and industrialization and agricultural intensification. Spatial distribution of heavy metals was a good indicator of natural and anthropogenic changes, where higher enrichment was found in the western lake. Apart from fluvial input, anthropogenic disturbances such as land use changes, atmospheric deposition, and algae-derived organic matter, along with natural stressors including climate change, hydrological alteration, and soil erosion, made significant contribution to the biogeochemical cycle of heavy metals in the lake. Heavy metals mainly from anthropogenic sources were dominantly partitioned in non-residual fractions, whereas those mainly from natural sources were predominantly distributed in residual form. Mercury and Cd were below the threshold effect concentration (TEC) indicating that adverse effects were excluded. However, result of chemical speciation demonstrated Cd would pose a considerable potential ecological risk. Besides, most of the heavy metals were in the range of TEC-PEC suggesting possible toxicity.
اظهر المزيد [+] اقل [-]Comparing artificial intelligence techniques for chlorophyll-a prediction in US lakes النص الكامل
2019
Luo, Wenguang | Zhu, Senlin | Wu, Shiqiang | Dai, Jiangyu
Chlorophyll-a (CHLA) is a key indicator to represent eutrophication status in lakes. In this study, CHLA, total phosphorus (TP), total nitrogen (TN), turbidity (TB), and Secchi depth (SD) collected by the United States Environmental Protection Agency for the National Lakes Assessment in the continental USA were analyzed. Statistical analysis showed that water quality variables in natural lakes have strong patterns of autocorrelations than man-made lakes, indicating the perturbation of anthropogenic stresses on man-made lake ecosystems. Meanwhile, adaptive neuro-fuzzy inference systems (ANFIS) with fuzzy c-mean–clustering algorithm (ANFIS_FC), ANFIS with grid partition method (ANFIS_GP), and ANFIS with subtractive clustering method (ANFIS_SC) were implemented to model CHLA in lakes, and modeling results were compared with the multilayer perceptron neural network models (MLPNN). Results showed that ANFIS_FC models outperformed other models for natural lakes, while for man-made lakes, MLPNN models performed the best. ANFIS_GP models have the lowest accuracies in general. The results indicated that ANFIS models can be screening tools for an overall estimation of CHLA levels of lakes in large scales, especially for natural lakes.
اظهر المزيد [+] اقل [-]