خيارات البحث
النتائج 4671 - 4680 من 4,937
Biochemical and genotoxic effects in women exposed to pesticides in Southern Ecuador النص الكامل
2019
Arévalo-Jaramillo, Paulina | Idrobo, Alicia | Salcedo, Lorena | Cabrera, Andrea | Vintimilla, Andrea | Carrión, Mayra | Bailon-Moscoso, Natalia
Toxicity refers to the potential of a substance such as a pesticide to cause damage to the structure or functions of an exposed organism. Pesticides can lead to harmful biological effects in exposed animals and their offspring over the medium and long term. They can affect the immunological, nervous, endocrine, and reproductive systems. DNA damage has also been linked to exposure to pesticides, and this damage can cause abortions, degenerative diseases, and cancer. The aim of this work was to establish whether women who are indirectly exposed to pesticides exhibit a compromised health status, including genotoxic effect. Women exposed indirectly to pesticides in Chimchanga and Colaisaca in the south of Ecuador underwent hematological and biochemical tests and micronucleus assay in buccal cells. The subjects were also genotyped for GSTM1, GSTT1, GSTP1, and PON1 polymorphisms, which can modify an individual’s capacity to metabolize pesticides and relation with damage of DNA. The study revealed hepatic toxicity in Colaisaca women (AST and ALT) and an increase in the rate of micronucleus (MN) in Colaisaca individuals. In addition, genetic polymorphisms in PON1 and GSTP1 showed effects of modulating the frequency of karyolytic cells, karyorrhectic cells, and condensed chromatin cells.
اظهر المزيد [+] اقل [-]Reclamation suitability evaluation of damaged mined land based on the integrated index method and the difference-product method النص الكامل
2019
Cheng, Linlin | Sun, Haiyuan
Reclamation suitability evaluation is the basis for determining the reuse direction of damaged land. Most scholars’ studies have focused on the improvement and innovation of evaluation models and methods, while the analysis of restrictive factors is rarely involved. This paper evaluates the reclamation suitability of damaged land around Longchi coal mine by the integrated index method and the analysis of restrictive factors is carried out by the difference-product method. The result shows damaged land around the Longchi coal mine is most suitable for being reclaimed as woodland. The main restrictive factors are the degree of contamination of the soil and water and the irrigation conditions. This study provides a basis for the rational reutilization and improvement options of damaged land around Long Chi coal mine. The study also verifies that the combination of the integrated index method and the difference-product method work well for evaluating reclamation suitability and for analyzing restrictive factors in case of no prominent evaluation indexes.
اظهر المزيد [+] اقل [-]Study on shear behavior of kaolinite contaminated by heavy metal Cu (II) النص الكامل
2019
Zhang, Zhihong | Chen, Yang | Fang, Jianghua | Guo, Fei
Numerous studies have shown that the invasion of the chemicals plays an important role on the geomechanical properties of the soil. This article aims to investigate the shear behavior of contaminated soil by laboratory tests and develop an extended shear strength model on the basis of the experimental results. In order to explicitly evaluate the effect of solution concentration on the shear strength behavior of soil, the remolded samples of kaolinite mixed with different concentrations of CuCl₂ solutions were prepared to carry out a series of consolidated-undrained triaxial shear strength tests. The results indicate that different CuCl₂ solution concentrations have significant influence on the shear strength property of kaolinite. With the increase of CuCl₂ solution concentration, the shear strength of soil displays a declining tendency, and the strength properties including cohesion and internal friction angle are also reduced, which indicates the Cu (II) that existed in the soil samples has deteriorated the soil strength strongly. Based on the experimental results, an extended Mohr–Coulomb strength model for contaminated soils has been proposed by introducing osmotic suction as a macro variable parameter. The conclusions in this study can provide reference for pollution prevention of existing and future foundations.
اظهر المزيد [+] اقل [-]Production of palm kernel shell-based activated carbon by direct physical activation for carbon dioxide adsorption النص الكامل
2019
Nor Adilla Rashidi, | Suzana Yusup,
The feasibility of biomass-based activated carbons has received a huge attention due to their excellent characteristics such as inexpensiveness, good adsorption behaviour and potential to reduce a strong dependency towards non-renewable precursors. Therefore, in this research work, eco-friendly activated carbon from palm kernel shell that has been produced from one-stage physical activation by using the Box-Behnken design of Response Surface Methodology is highlighted. The effect of three input parameters—temperature, dwell time and gas flow rate—towards product yield and carbon dioxide (CO₂) uptake at room temperature and atmospheric pressure are studied. Model accuracy has been evaluated through the ANOVA analysis and lack-of-fit test. Accordingly, the optimum condition in synthesising the activated carbon with adequate CO₂ adsorption capacity of 2.13 mmol/g and product yield of 25.15 wt% is found at a temperature of 850 °C, holding time of 60 min and CO₂ flow rate of 450 cm³/min. The synthesised activated carbon has been characterised by diverse analytical instruments including thermogravimetric analyser, scanning electron microscope, as well as N₂ adsorption-desorption isotherm. The characterisation analysis indicates that the synthesised activated carbon has higher textural characteristics and porosity, together with better thermal stability and carbon content as compared to pristine palm kernel shell. Activated carbon production via one-step activation approach is economical since its carbon yield is within the industrial target, whereas CO₂ uptake is comparable to the synthesised activated carbon from conventional dual-stage activation, commercial activated carbon and other published data from literature.
اظهر المزيد [+] اقل [-]Double dielectric barrier discharge cells for promoting the catalytic degradation of volatile organic compound released by industrial processes النص الكامل
2019
Zhang, Shuo | Shen, Xinjun | Liang, Jiyan
In this study, the recycling of gas flow was added to oxidize mixture (toluene and xylene) in the post-plasma catalysis (PPC) system, and the MnOx catalysts using impregnation method were used to further oxidize the VOC mixture. The circulation and catalysts were of enhancement for the plasma degradation on both toluene and xylene. The improvement of CO₂ selectivity and the reduction of NO, NO₂, and O₃ were 64.4%, 92.0%, 62.2%, and 51.9%, respectively. The fresh and used catalysts were characterized for the ozone decomposition and mixture degradation in the NTP-REC-CATAL system with the 15 wt% loading amount of catalysts. The results showed that OH groups, lattice oxygen, and manganese sites were potential and significant for the catalytic ability for O₃ and mixture conversion. Aldehyde was detected from FT-IR characterization after treating, which indicates that it is the main intermediate NTP-REC-CATAL process. The air plasma was employed to reactive catalytic activity.
اظهر المزيد [+] اقل [-]Identifying effects of pipe material, hydraulic condition, and water composition on elemental accumulation in pipe corrosion scales النص الكامل
2019
Li, Manjie | Liu, Zhaowei | Chen, Yongcan | Zhang, Mingdong
Identification of the accumulation mechanism of major elements on pipe surface is essential to investigate the development of corrosion scales and co-occurrence of trace inorganic contaminants. In this study, corrosion scale samples were collected from old, corroded iron pipes made of different materials and exposed to different water qualities and operation conditions. Elemental composition of these scales was determined by energy dispersive X-ray spectroscopy (EDS). Cumulative occurrence analysis, Q-style hierarchical cluster analysis (CA), and principal component analysis (PCA) were conducted to ascertain major elements typical for corrosion scales and to estimate the dominant influencing factor to each elemental constituent. The major elements in the examined scales are Fe, C, Zn, Si, Ca, Al, and S in the descending prevalence. Their occurrences are influenced by an interactive effect. Pipe material imposes a significant effect on the accumulation of Fe, Zn, and Ca in corrosion scales; water composition can account for the presence of Si, Al, and S in this study; hydraulic condition is identified as the primary factor influencing the occurrence of C and Ca. Q-style CA and PCA are verified practicable for data interpretation and identification of dominant factors influencing scale characteristics.
اظهر المزيد [+] اقل [-]Electricity consumption and economic growth nexus in China: an autoregressive distributed lag approach النص الكامل
2019
Zhong, Xiaojian | Jiang, Hongyi | Zhang, Chen | Shi, Rui
This study attempts to investigate the relationship among electricity consumption, economic growth, and employment in China. Distinct from most of the previous studies, our empirical research identifies a long-run equilibrium cointegration relationship among the three covariates during the period of 1971–2009 with the recently developed autoregressive distributed lag (ARDL) bounds testing approach. The parameters are estimated through a long-run static solution of the estimated ARDL model and short-run dynamic solutions of the error correction model. The estimated models successfully pass diagnostic tests and both the long-run and short-run elasticities are found to be statistically significant. The study also indicates the existence of short-run and long-run causalities from electricity consumption and employment to economic growth. Results of this study show that electricity serves as an important driver of economic growth. Based on these results, several policy prescriptions on energy use and economic development are suggested for China.
اظهر المزيد [+] اقل [-]Adsorption of ciprofloxacin and Cu2+ onto biochars in the presence of dissolved organic matter derived from animal manure النص الكامل
2019
Yang, Zhenyu | Xing, Rong | Zhou, Wenjun
Biochar are widely used as adsorbents/amendments for immobilizing pollutants in contaminated soils. In this study, the effects of dissolved organic matter derived from chicken manure (CMDOM) on the adsorption of ciprofloxacin (CIP) and Cu²⁺ onto biochars were investigated. The FTIR spectra indicated that π-π donor-acceptor interactions between the hydroxyl groups on the biochar surface and the fluorine group connected to the benzene ring of CIP molecule was the main adsorption mechanism for CIP. CMDOM molecules interacted with the aromatic components in biochars and thus modified the surface chemical properties of biochar. The effect of CMDOM on the adsorption of CIP onto biochars showed great dependence on the distribution of solid adsorbed CMDOM and CMDOM in aqueous solutions. The solid adsorbed CMDOM facilitated CIP adsorption owing to increase the content of –OH on biochar surface, which could provide more π-electron donors and thus strengthened π-π EDA interactions between CIP and biochars. The EDS spectra showed that the ion exchange with K⁺ was the main adsorption mechanism for Cu²⁺ onto biochars, and the presence of CMDOM enhanced complexation of Cu²⁺ with adsorbed CMDOM, thus increasing Cu²⁺ adsorption onto biochars. These results are useful for the application of biochars to immobilize antibiotic and heavy metals in contaminated farmland soils when animal manure fertilizers is presented in soil environment.
اظهر المزيد [+] اقل [-]Do renewable energy consumption and service industry development contribute to CO2 emissions reduction in BRICS countries? النص الكامل
2019
Zhang, Yue-Jun | Wang, Wei
In recent years, BRICS countries have attached great importance to renewable energy development and actively promoted the shift of economic structure towards service industry, in order to achieve the decoupling of economic development from carbon emissions. However, relevant studies mostly neglect the cross-sectional dependence and heterogeneity issues, which may cause biased results. Therefore, this paper selects the panel data of BRICS countries during 1996–2017 and employs the common correlated effects mean group (CCEMG) method, which are based on the cross-sectional dependence and heterogeneity assumptions, to explore the influence of renewable energy consumption and service industry development on CO₂ emissions in BRICS countries. Besides, we also use the random effects model and pooled estimated generalized least squares model, as well as fully modified OLS model for comparison. The results indicate that enhancing the proportion of renewable energy consumption in the total energy consumption is an effective measure to reduce CO₂ emissions in BRICS countries. Moreover, the steadily rising contribution of service industry to economic growth in BRICS countries during the sample period does not necessarily contribute to reduce CO₂ emissions.
اظهر المزيد [+] اقل [-]Decomposition and decoupling analysis of energy-related carbon emissions in Turkey النص الكامل
2019
Karakaya, Etem | Bostan, Aziz | Özçağ, Mustafa
This study focuses on CO₂ emission trends and its decompositions as well as decoupling performance between CO₂ emissions and economic growth of Turkish case for the period of 1990–2016. The drivers of CO₂ emission changes are calculated by using an extended Kaya identity and the well-established logarithmic mean Divisia index (LMDI) method. Decomposition results indicate that economic growth and population effects are the main driving forces in increases in carbon emissions in Turkey throughout the whole period, while other technology-based driving factors’ impacts have been rather minimal in reducing the emissions. Decoupling analysis results demonstrate that there is either no decoupling or weak decoupling in most of the years. Moreover, total decoupling effort index suggests that Turkey’s performance has been worsened in recent years as we found no decoupling between CO₂ emissions and economic growth over the period of 2013–2016. The overall findings suggest that Turkish economic growth is unsustainable both environmentally and economically. Based on these findings, some policy implications and recommendations are discussed for the possible emission reductions.
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