Refine search
Results 4821-4830 of 4,924
Effects of extreme temperatures on hospital emergency room visits for respiratory diseases in Beijing, China Full text
2019
Ma, Yuxia | Zhou, Jianding | Yang, Sixu | Yu, Zhiang | Wang, Fei | Zhou, Ji
Extreme temperature is closely associated with human health, but limited evidence is available for the effects of extreme temperatures on respiratory diseases in China. The goal of this study is to evaluate the effects of extreme temperatures on hospital emergency room (ER) visits for respiratory diseases in Beijing, China. We used a distributed lag non-linear model (DLNM) coupled with a generalized additive model (GAM) to estimate the association between extreme temperatures and hospital ER visits for different age and gender subgroups in Beijing from 2009 to 2012. The results showed that the exposure-response curve between temperature and hospital ER visits was almost W-shaped, with increasing relative risks (RRs) at extremely low temperature. In the whole year period, strong acute hot effects were observed, especially for the elders (age > 65 years). The highest RR associated with the extremely high temperature was 1.36 (95% CI, 0.96–1.92) at lag 0–27. The longer-lasting cold effects were found the strongest at lag 0–27 for children (age ≤ 15 years) and the relative risk was 1.96 (95% CI, 1.70–2.26). We also found that females were more susceptible to extreme temperatures than males.
Show more [+] Less [-]Per capita income, trade openness, urbanization, energy consumption, and CO2 emissions: an empirical study on the SAARC Region Full text
2019
Afridi, Muhammad Asim | Kehelwalatenna, Sampath | Naseem, Imran | Ṭāhir, Muḥammad
The developing world in general is facing so many crucial problems including global warming in recent years. Global warming has multiple consequences on each segment of the society and therefore, its root causes are important to identify. The present study examines the impact of per capita income, trade openness, urbanization, and energy consumption on CO₂ emissions. Countries located in South Asian Association for Regional Cooperation (SAARC) are considered in the study. The selection of the SAARC region is motivated by the diverse nature of its members and further lack of available empirical literature on the same relationship. Annual data from 1980 to 2016 are analyzed using appropriate panel data techniques. The results revealed the presence of environmental Kuznets curve (EKC) in the SAARC region. Further, the introduction of cubic function into the model indicated that the shape of the EKC is N shaped. Besides, trade openness has negative while urbanization and energy consumption have impacted CO₂ emissions positively. Moreover, the causality exercise explored a bidirectional causality between urbanization, energy consumption, per capita income, and CO₂ emissions. Similarly, energy consumption, per capita GDP, and urbanization are also bidirectionally related. Further, a unidirectional causality running from CO₂ emissions, urbanization, and energy consumption to trade openness is detected. Lastly, a unidirectional causality is witnessed from per capita income to energy consumption.
Show more [+] Less [-]Design and analysis of continuous-flow reactors for copper sulfide precipitation process by a computational method Full text
2019
Yang, Zhihui | Li, Bo | Zeng, Weizhi | Xiao, Gen | Liu, Shan | Hu, Hui | Guo, Wenxiang
Sulfide precipitation method has been widely applied in heavy metal–polluted wastewater treatment, due to the low solubility of most metal sulfide precipitates. Nevertheless, the relevant hydrodynamics studies on the metal sulfide precipitation process are rarely found in the literature. In this study, three continuous-flow sulfide precipitation reactors (CFSPRs) were designed and evaluated by a computational method. To characterize the process efficiency of copper sulfide precipitation in different reactors, fluid velocity field, species concentration distribution, and reaction rate distribution maps were acquired as simulation results. A two-factor designed set of boundary conditions was used to determine their effects on processing efficiency. The model results indicate that the inflow rate and reactor layout have significant effects on the copper sulfide precipitation process. The layout of reactor no. 3 and the inflow rate of 0.75 m/s prove to have higher treatment efficiencies than those at other conditions. Possible explanations for the simulation results were proposed. The model data of effluent concentration were compared and statistically analyzed with the measured concentrations of copper ion and sulfur ion in the outlet stream, and the results demonstrate a strong correlation between them, which suggests the model is reasonably accurate.
Show more [+] Less [-]Protective role of curcumin in cadmium-induced testicular injury in mice by attenuating oxidative stress via Nrf2/ARE pathway Full text
2019
Yang, Shuhua | He, Jian-Bin | Yu, Li-Hui | Li, Lin | Long, Miao | Liu, Ming-Da | Li, Peng
The aim of the present study was to investigate whether curcumin (CUR) can ameliorate cadmium-induced reproductive toxicity and its mechanism. A total of 48 male mice were equally divided into 4 groups: control, CdCl₂ (2 mg/kg, intraperitoneally inject) curcumin (50 mg/kg, intraperitoneally inject), co-treatment with curcumin (50 mg/kg), and CdCl₂ (2 mg/kg) for 10 days. The results demonstrated that CdCl₂ reduces sperm motility, decreases the sperm density and serum testosterone content, and significantly improves the rate of sperm deformity. CdCl₂ increased the level of testicular total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) activity, and glutathione (GSH), and CdCl₂ declined the level of malondialdehyde (MDA). However, the semen quality of the mice in the curcumin intervention group was improved. Moreover, the testosterone content and antioxidant capacity were increased. In the Cd group mice, the expression of testicular Nrf2, as well as the mRNA and protein expressions of the downstream target molecules, glutathione peroxidase (GSH-Px), and γ-glutamylcysteine synthetase (γ-GCS) of Nrf2 declined, while the above genetic expressions elevated significantly in the curcumin intervention group. Our results suggested that curcumin could protect against Cd-induced testicular injury via activating the Nrf2/ARE signaling pathway.
Show more [+] Less [-]Impact of market misallocations on green TFP: evidence from countries along the Belt and Road Full text
2019
Zhang, Qing | Yan, Fenghao | Li, Ke | Ai, Hongshan
Based on the idea of a “Community of Human Destiny,” the Chinese government proposed the “Belt and Road” initiative, and clearly proposed to promote green development and strengthen ecological environmental protection. However, a considerable number of countries are resource-rich economies with serious market misallocations. Using the stochastic frontier analysis (SFA) combined with the directional distance function (DDF) framework, this paper measures the green total factor productivity (GTFP) and its items (i.e., technical change and efficiency change) of 33 countries along the Belt and Road in 1995–2012, and then the impact of market misallocations on GTFP is analyzed. The following conclusions are drawn: (1) The main driving force for GTFP promotion in Asian countries came from technical change, while in European countries, it came from efficiency change. (2) Market misallocations had significantly hindered the GTFP of these economies. Countries with greater market misallocations have smaller GTFP. (3) Results based on counterfactual measures showed that GTFP could be increased by up to 4.04% and the average can be increased by 1.24% after eliminating market misallocations.
Show more [+] Less [-]Simultaneous removal of metronidazole and Pb(II) from aqueous solution onto bifunctional activated carbons Full text
2019
Segovia Sandoval, Sonia Judith | Padilla Ortega, Erika | Carrasco-Marín, Francisco | Berber Mendoza, María Selene | Ocampo-Pérez, Raúl
In this work, it was analyzed the behavior of three commercial activated carbons with different textural and chemical properties to adsorb individually metronidazole and lead ions from aqueous solution. Afterwards, the activated carbons were modified with citric acid to remove both compounds simultaneously. Both sets of activated carbons were characterized chemically and texturally. XPS analysis was performed to corroborate the adsorption mechanism of lead on the surface of the carbons. Finally, the intraparticle diffusion of both adsorbates was elucidated by the application of diffusional model in three dimensions. The results evidenced that adsorption mechanism for MNZ and Pb(II) is independent, the adsorption for MNZ is governed by π–π dispersive interactions, whereas Pb(II) adsorption is mainly controlled by electrostatic interactions. The binary adsorption equilibrium shows that the adsorption of MNZ is independent from the concentration of Pb(II), whereas the adsorption of Pb(II) is affected by the presence of MNZ at low concentrations (0.1 mmol L⁻¹), but it remains almost constant at concentrations of MNZ between 0.1 and 1.5 mmol L⁻¹. Finally, the mass transport of MNZ was faster than Pb(II) from the solution to the external surface of activated carbon and the mass flux of MNZ inside the particle was superior to the mass flux of Pb(II). Lastly, there might be an obstruction phenomenon with MNZ impeding Pb(II) to reach the active sites placed into the carbon’s microporosity structure. Graphical abstract
Show more [+] Less [-]Assessment of occupational exposure to pesticide mixtures with endocrine-disrupting activity Full text
2019
Wong, Hie Ling | Garthwaite, David G. | Ramwell, Carmel T. | Brown, Colin D.
Occupational exposure to pesticide mixtures comprising active substance(s) and/or co-formulant(s) with known/possible endocrine-disrupting activity was assessed using long-term activity records for 50 professional operators representing arable and orchard cropping systems in Greece, Lithuania, and the UK. Exposure was estimated using the harmonised Agricultural Operator Exposure Model, and risk was quantified as a point of departure index (PODI) using the lowest no observed (adverse) effect level. Use of substances with known/possible endocrine activity was common, with 43 of the 50 operators applying at least one such active substance on more than 50% of spray days; at maximum, one UK operator sprayed five such active substances and 10 such co-formulants in a single day. At 95th percentile, total exposure was largest in the UK orchard system (0.041 × 10⁻² mg kg bw⁻¹ day⁻¹) whereas risk was largest in the Greek cropping systems (PODI 0.053 × 10⁻¹). All five cropping systems had instances indicating potential for risk when expressed at a daily resolution (maximum PODI 1.2–10.7). Toxicological data are sparse for co-formulants, so combined risk from complex mixtures of active substances and co-formulants may be larger in reality.
Show more [+] Less [-]Bacterial community activity and dynamics in the biofilm of an experimental hybrid wetland system treating greywater Full text
2019
Truu, Marika | Oopkaup, Kristjan | Krustok, Ivo | Kõiv-Vainik, Margit | Nõlvak, Hiie | Truu, Jaak
The objectives of this study were to determine the biofilm microbial activity and bacterial community structure and successions in greywater treatment filters and to relate the treatment efficiency to the bacterial community parameters. This 10-month study was performed in a newly established experimental system for domestic greywater treatment that consisted of three parallel vertical flow filters (VFs) followed by a horizontal flow filter (HF). A rapid increase in the bacterial community abundance occurred during the first 85 days of filter operations, followed by a short-term decrease and the stabilization of the 16S rRNA gene copy numbers at average levels of 1.2 × 10⁹ and 3.2 × 10⁸ copies/g dw in VFs and HF, respectively, until the end of the experiment. The dominant bacterial phyla and genera differed between the VFs and HF. The temporal variation in the bacterial community structure was primarily related to the species replacement, and it was significantly affected by the influent organic carbon and nitrogen compounds in the VFs and the ammonia and organic carbon in the HF filters. Despite the differences in the community structure and assembly mechanisms, the temporal dynamics of the bacterial community showed high congruence between the filter types. The treatment efficiency was related to the biofilm bacterial community diversity and abundance and the abundance of certain bacterial genera in the VF filters. The results suggest that the dominant pathway of nitrogen removal by greywater treatment VFs occurs via coupled heterotrophic nitrification and denitrification, while the contribution of aerobic denitrification is temporally variable in these filters.
Show more [+] Less [-]Potential control of toxic cyanobacteria blooms with Moroccan seaweed extracts Full text
2019
El Amrani Zerrifi, Soukaina | Tazart, Zakaria | El Khalloufi, Fatima | Oudra, Brahim | Campos, Alexandre | Vasconcelos, Vitor
Marine macroalgae are a promising source of diverse bioactive compounds with applications in the biocontrol of harmful cyanobacteria blooms (cyanoHABs). In this work, we evaluated the potential algicidal activities of 14 species of seaweed collected from the coast of Souiria Laqdima, Morocco. Methanol extracts were screened in solid and liquid medium against the growth of the toxic cyanobacteria Microcystis aeruginosa and the microalgae Chlorella sp. used as food supplement. The results in solid medium revealed that the algicidal activity was limited to M. aeruginosa with the extract of Bornetia secundiflora showing the highest growth inhibition activity against Microcystis (27.33 ± 0.33 mm), whereas the extracts of Laminaria digitata, Halopytis incurvus, Ulva lactuca, and Sargasum muticum showed no inhibition. In liquid medium, the results indicated that all methanolic extracts of different macroalgae tested have a significant inhibitory effect on M. aeruginosa compared with that of the negative control. The maximum inhibition rates of M. aeruginosa were produced by the extracts of Bifurcaria tuberculata, Codium elongatum, and B. secundiflora. Moreover, the extracts of B. secundiflora recorded the maximum inhibition rate of Chlorella sp. Overall, the results highlight the potential of the extracts from macroalgae to control toxic cyanobacteria species.
Show more [+] Less [-]Application of different single extraction procedures for assessing the bioavailability of heavy metal(loid)s in soils from overlapped areas of farmland and coal resources Full text
2019
Luo, Ping | Xiao Xin, | Han, Xiaoxuan | Ma, You | Sun, Xiaofei | Jiang, Jiachao | Wang, Hui
Heavy metal(loid) extraction from soils in overlapped areas of farmland and coal resources (OAFCR) is crucial in understanding heavy metal bioavailability in soil and the subsequent risks to crops and consumers. However, limited attention has been paid to the extraction procedure of heavy metal(loid)s in OAFCR soils in the research. This study therefore explored different single and mixed extraction procedures, such as acetic acid (HOAc), citric acid, ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA), ethylene diamine tetraacetic acid + ammonium acetate (EDTA+NH₄OAc), and total digestion (HNO₃-HClO₄-HF) to determine the bioavailability of As, Cd, Cr, Cu, Pb, and Zn in OAFCR soil in Xuzhou, China. The results showed the metal(loid) extraction capacity from soil of the different procedures could be ranked as AB-DTPA > EDTA+NH₄OAc > HOAC > citric acid. The transfer ability of heavy metal(loid)s from soil to wheat tissues and from wheat roots to aerial parts was analyzed by calculating the bioconcentration factor and transfer factor, respectively. Transfer factors of all metal(loid)s were < 1 except Cr whose transfer factor from root to shell and straw were > 1. It is suspected that foliar uptake plays a dominant role in Cr uptake. Correlation analysis between the bioavailability of heavy metal(loid)s in soil and uptake in respective wheat tissues was performed to recommend the best extraction procedures for different studies. The results show that AB-DTPA extraction is recommended for Cu uptake to wheat roots, straws, shells and grains, Zn uptake to roots, and Cd uptake to roots and straws.
Show more [+] Less [-]