خيارات البحث
النتائج 4301 - 4310 من 6,558
Protective effects of quercetin against oxidative stress induced by bisphenol-A in rat cardiac mitochondria النص الكامل
2020
Vanani, Atefeh Raesi | Mahdavinia, Masoud | Shirani, Maryam | Alizadeh, Said | Dehghani, Mohammad Amin
Research has shown a relationship between the exposures to a chemical agent called bisphenol-A (BPA), which is extensively used in the production of polycarbonate plastics and the incidence of cardiovascular diseases. This association is most likely caused by the BPA’s ability to disrupt multiple cardiac mechanisms, including mitochondrial functions. Therefore, this study aimed to explore the ability of quercetin (QUER) to limit the cardiotoxic effect of BPA in the rat’s cardiac mitochondria. The experiment was carried out on 32 male Wistar rats, which were randomly assigned to four groups. The negative control group received olive oil; the positive control group received olive oil plus BPA (250 mg/kg); the third group received olive oil, BPA, and QUER (75 mg/kg); and the fourth group received olive oil and QUER, all orally for 14 days. The rats were slaughtered 24 h after the last treatment. The measured parameters included creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) as the biomarkers of cardiotoxicity, triglyceride (TG), total cholesterol (TC), and low-density and high-density lipoprotein cholesterol (LDL-C and HDL-C) as the measures of dyslipidemia, glutathione (GSH) content, catalase activity (CAT), reactive oxygen species (ROS), lipid peroxidation (LPO), and the level of damage to the mitochondrial membranes as the indicators of the impact of QUER on the BPA cardiotoxic effect. Finally, the rats treated with QUER showed better results in terms of serum CK-MB, serum LDH, serum lipid profile, GSH level, CAT activity, mitochondrial membrane potential (ΔΨm), LPO, and ROS. According to the results, QUER could be used as a protective agent against BPA-induced mitochondrial toxicity.
اظهر المزيد [+] اقل [-]Forecasting the annual household electricity consumption of Chinese residents using the DPSO-BP prediction model النص الكامل
2020
Wen, Lei | Yuan, Xiaoyu
In recent years, global climate change caused by carbon dioxide emissions has attracted more and more attention. Adjusting the energy mix by predicting energy demands is currently a more effective way to address climate issues and energy supply issues. Based on the panel data from 1999 to 2018 in China, this paper designed a new hybrid prediction model to predict the future electricity consumption of Chinese residents by double improvement of particle swarm optimization. By comparing with the BP neural prediction model without mixing and several BP neural prediction models with other improved and mixed forms, the results show that the BP neural network hybrid prediction model with DPSO-BP is more suitable for forecasting the electricity consumption of Chinese residents. At the same time, the prediction results of the DPSO-BP prediction model show that the annual electricity consumption of Chinese residents will increase from 9685 (100 million kWh) in 2018 to 13,171 (100 million kWh) in 2025 in the next 7 years. The research results provide a reference for future scholars in the design of algorithms and provide suggestions for the government to adjust energy and avoid severe power shortages or surpluses. Graphical abstract In this paper, a new hybrid prediction model is established to predict the annual electricity consumption of Chinese residents. To achieve the research purposes, a brief flowchart of the work of this study is shown in Fig. 1.
اظهر المزيد [+] اقل [-]Study on mechanical and permeability characteristics of nickel-copper-contaminated soil solidified by CFG النص الكامل
2020
Wang, Qiang | Li, Man | Yang, Jingdong | Cui, Jinyang | Zhou, Wenjun | Guo, Xiaoliang
The study introduces the potential use of a novel curing agent formed by mixing cement, fly ash, and desulfurization gypsum (CFG) for the stabilization/solidification of nickel-copper-contaminated soil. According to the tests of the unconfined compressive strength (UCS), permeability, and scanning electron microscope (SEM), the samples’ characteristics, which include UCS, deformation, and permeability, are investigated under different curing time, ion concentration, and curing agent content. The correlation between the UCS and permeability of samples is estimated. The results demonstrates that the gradual increase of the UCS and impermeability of the samples can be recognized with the increase of curing age; however, the failure strain decreased gradually but the trend is reversed with the increase of heavy metal concentration. Besides, greater amounts of CFG results in better mechanical and impermeability properties. The correlation between UCS and permeability coefficient reveals that the UCS of contaminated soil is significantly negatively correlated with permeability coefficient, and the prediction formulas of permeability coefficient based on age and CFG content are given respectively. Moreover, the microscopic analysis demonstrates that the hydration products calcium silicate hydrate(C-S-H) and ettringite (AFt) of CFG curing agent are the main reasons for the enhancement of the UCS and impermeability of contaminated soil. However, the increase of nickel and copper concentration leads to the decrease of hydration products and the compactness of solidified soil, which is the reason for the weakening of the compressive strength and impermeability of contaminated soil.
اظهر المزيد [+] اقل [-]Land cover mapping using Sentinel-1 SAR and Landsat 8 imageries of Lagos State for 2017 النص الكامل
2020
Makinde, Esther Oluwafunmilayo | Oyelade, Edward Oluwasegun
For several years, Landsat imageries have been used for land cover mapping analysis. However, cloud cover constitutes a major obstacle to land cover classification in coastal tropical regions including Lagos State. In this work, a land cover appearance for Lagos State is examined using Sentinel-1 synthetic aperture radar (SAR) and Land Satellite 8 (Landsat 8) imageries. To this aim, a Sentinel-1 SAR dual-pol (VV+VH) Interferometric Wide swath mode (IW) data orbit for 2017 and a Landsat 8 Operational Land Imager (OLI) for 2017 over Lagos State were acquired and analysed. The Sentinel-1 imagery was calibrated and terrain corrected using a SRTM 3Sec DEM. Maximum likelihood classification algorithm was performed. A supervised pixel-based imagery classification to classify the dataset using training points selected from RGB combination of VV and VH polarizations was applied. Accuracy assessment was performed using test data collected from high-resolution imagery of Google Earth to determine the overall classification accuracy and Kappa coefficient. The Landsat 8 was orthorectified and maximum likelihood classification algorithm also performed. The results for Sentinel-1 include an RGB composite of the imagery, classified imagery, with overall accuracy calculated as 0.757, while the kappa value was evaluated to be about 0.719. Also, the Landsat 8 includes a RBG composite of the imagery, classified imagery, but an overall accuracy of 0.908 and a kappa value of 0.876. It is concluded that Sentinel 1 SAR result has been effectively exploited for producing acceptable accurate land cover map of Lagos State with relevant advantages for areas with cloud cover. In addition, the Landsat 8 result reported a high accuracy assessment values with finer visual land cover map appearance.
اظهر المزيد [+] اقل [-]Asymmetrical ARDL correlation between fossil fuel energy, food security, and carbon emission: providing fresh information from Pakistan النص الكامل
2020
Naseem, Snovia | Guang Ji, Tong | Kashif, Umair
The core objective of our study seeks to examine the asymmetrical impact of agriculture, fossil fuel consumption, and food security on carbon emission (CO₂) in Pakistan from 1969 to 2018. The current study applied multiple unit root tests (ADF, PP, and KPSS, Z&A) to check data stationarity and structural breaks. We used the population data as a food security proxy indicator. The outcomes disclosed that there is a long-term asymmetric relationship between the variables. The results also verified the atypical response of CO₂ to adverse shocks in agricultural value-added. Furthermore, the results showed that population and fossil fuel consumption would further worsen environmental standards. Based on the results of the study, the government needs to take practical steps for active policy-making and assessing ecological challenges in Pakistan.
اظهر المزيد [+] اقل [-]Correction to: Intelligent-activated carbon prepared from pistachio shells precursor for effective adsorption of heavy metals from industrial waste of copper mine النص الكامل
2020
Nejadshafiee, Vajihe | Islami, Mohammad Reza
The original publication of this paper contains a mistake.
اظهر المزيد [+] اقل [-]Valuing urban air quality: a hedonic price analysis in Beijing, China النص الكامل
2020
Mei, Yingdan | Gao, Li | Zhang, Jiawei | Wang, Jiahao
Although Chinese government has implemented a series of laws, regulations, and policies to deal with air pollutants, air pollution is still one of the biggest concerns in China. Most of the cities in China suffered from extremely high air pollution levels and cannot meet the national air quality standards. In this study, we attempt to measure individuals’ average marginal willingness to pay (MWTP) in Beijing with the hedonic price model. We combine an extensive housing transaction dataset with emission data of six air pollutants from 2013 to 2016 in Beijing, China. When estimating the hedonic price function, we apply both ordinary least squares (OLS) and panel model with various fixed effects to better control for unobservables. The empirical results reveal that the concentrations of CO, NO₂, PM₂.₅, and PM₁₀ are significantly negatively correlated with housing prices. However, we found an insignificant relationship with the concentration of SO₂ and the concentration of O₃ appears to positively increase the housing values. Policy implications based on these results were also discussed.
اظهر المزيد [+] اقل [-]A rapid experimental protocol to determine the desorption resistant fraction of sediment-sorbed hydrophobic organic contaminants النص الكامل
2020
Zhang, Ping | Huang, Siyuan | Kan, Amy T. | Tomson, Mason B.
Desorption of hydrophobic organic contaminants (HOCs) from sedimentary materials plays a vital role in dictating the fate and transport of HOCs in the environment. Desorption irreversibility is a commonly observed phenomenon in laboratory sorption/desorption studies of HOCs. A desorption-resistant fraction (DRF) typically exists during the desorption process. To correctly evaluate the DRF of HOCs can considerably contribute to the understanding of availability and bioavailability of HOCs. This can substantially benefit contaminant remediation and cleanup operations. Conventional batch method to measure the DRF replies on repetitive washing of the sediments, which is time-consuming and can be impractical. This study presents an experimental protocol to quantify the DRF of the sediment-sorbed organic contaminants in a rapid manner. This protocol utilizes cosolvent to expedite desorption kinetics and adopts an ultrafiltration/centrifugation combined method to achieve a complete separation of sediment and solution phases. This proposed experimental protocol can facilitate the quantification of the DRF of sorbed contaminants to understand and minimize the uncertainties associated with risk-based pollution remediation approach. This protocol has the potential to be widely used in environmental studies to characterize sorption and desorption properties of HOCs with soil and sedimentary materials.
اظهر المزيد [+] اقل [-]Organic carbon storage and its influencing factors under climate warming of sediments in steppe wetland, China النص الكامل
2020
He, Jing | Xie, Jingjie | Su, Derong | Zheng, Zhirong | Diao, Zhaoyan | Lyu, Shihai
The effect of climate warming on soil organic carbon (SOC) of sediment in wetlands is important for accurately projecting SOC content. Thus, understanding the mechanism influencing SOC content under climate warming is necessary. Field investigation and a laboratory incubation experiment were conducted in Hulunbeier steppe wetland during 2016 and 2017. Four types of wetland were selected to incubate with ambient temperature and temperature increased by 2.5 °C. The results showed that SOC content was negatively affected by temperature warming. The SOC content reduction in sediment caused by increasing temperature was ranged from − 2.34 to 39.52%. In addition, the content of sand, silt, total phosphorus (TP), calcium phosphate tribasic (Ca-P), total nitrogen (TN), and sediment moisture (MC) should be considered in models of SOC content in steppe wetland. However, it requires further validation, in particular how SOC content varies with warming temperatures, the duration of incubation, and other abiotic and biotic factors. These findings provide evidence that both climate warming and original characteristics of sediment can control the SOC storage dynamics in the steppe wetland. Graphical abstract
اظهر المزيد [+] اقل [-]Sorption behavior of Arachis hypogaea shells against Ag+ ions and assessment of antimicrobial properties of the product النص الكامل
2020
Staroń, Paweł | Pszczółka, Krzysztof | Chwastowski, Jarosław | Banach, Marcin
The paper presents sorption behavior of Arachis hypogaea shells towards silver ions and possibility of their use as antimicrobial product. During the modification process of the natural sorbent, equilibrium tests were carried out. Moreover, the possibility of obtaining biocomposite Arachis hypogaea shells/nAg has been determined, and its antimicrobial properties have been evaluated. Additionally, sorption kinetics has been calculated. In the last step, silver ions were desorbed. The conducted equilibrium tests allowed to adjust the sorption isotherm model and determine the sorption capacity of tested material. This process is best described by Freudlich’s isotherm, and the sorption capacity is equal to 12.33 mg/g. On the basis of kinetic studies, the chemical nature of this process has been proved (by choosing a pseudo-second order model for the sorption process). It has been confirmed that the obtained peanut shells modified with silver ions have antimicrobial properties. The tests allowed to obtain 100% inhibition of Aspergillus niger and ~ 98% Escherichia coli.
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