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Resultados 5401-5410 de 6,560
The influence of flow rates and water depth gradients on the growth process of submerged macrophytes and the biomass composition of the phytoplankton assemblage in eutrophic water: an analysis based on submerged macrophytes photosynthesis parameters Texto completo
2020
Xu, Duo | Xia, Yan | Li, Zhaoxin | Gu, Yonggang | Lou, Chunhua | Wang, Hao | Han, Jinlong
Submerged macrophytes and phytoplankton assemblage play significant roles in the functioning of aquatic ecosystems. An experiment was carried out in Beijing in order to further evaluate the environmental factors that affect the growth of submerged macrophytes and phytoplankton assemblage. Submerged macrophytes (i.e., Vallisneria natans, Hydrilla verticillata, and Ceratophyllum demersum) constructed the growth system with some controllable influencing factors (i.e., the flow rate and water depth gradient). The flow rates were set separately as 4 L/h (1#), 6 L/h (2#), and 12 L/h (3#), while the water depth gradient was of 0.5–1.7 m in eutrophic water. Generally, all macrophytes could grow normally in the experiment, and the system could maintain and improve the effluent quality. The average removal rates of NH₃-N, COD, NO₃-N, TN, and TP were about 90%, 33%, 65%, 45%, and 40%, respectively. Seen from the results of the water depth gradient experiments, it is indicated that Vallisneria natans grows better in shallow water (0.5 m) and moderate shallow water (0.7 m) area, with an average relative growth rate (ARGA) of 57%. Hydrilla verticillata and Ceratophyllum demersum grow better in moderate deep water (1.2 m) and deep water (1.7 m) area (ARGA of 66% and 64%, respectively). Results of the flow rate experiments showed that the moderate flow rate (6 L/h) was the best for those three macrophytes’ growth. As the fitting results of the rapid light curves (RLCs) showed that the utilization of light and the tolerance to strong light were different for these macrophytes, if they are ranked in the order of the utilization and the tolerance from strong to weak, they are Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans. Microbial analyses indicated that the overall system diversity of the experimental groups have been improved after cultivation of macrophytes. However, the accumulated Cyanobacteria caused by the low flow rate (1#) would lead to the suppression of microbial organics decomposition and nutrient metabolism in the macrophytes. To sum up, the results of this study provided theoretical guidance and technical support for the restoration of submerged macrophytes in eutrophic water.
Mostrar más [+] Menos [-]Threshold effects of economic growth on water stress in the Eurozone Texto completo
2020
Esen, Ömer | Yıldırım, Durmuş Çağrı | Yıldırım, Seda
This paper empirically examines the environmental Kuznets curve (EKC) hypothesis using a country’s water stress as an indicator of the pressure on renewable water resources. The sample consists of 9 European countries by covering the period 1995–2013. The paper adopts a panel threshold regression model which can predict the threshold level endogenously to analyze whether income per person has an impact on water stress. The empirical findings strongly demonstrate the existence of a threshold beyond which environmental pressures of GDP (real) per capita growth on renewable water resources tend to increase. The growth below the threshold levels has no statistically significant effect on water stress, while the growth rate above the threshold increases stress on water resources. The available empirical findings obtained, albeit limited, tend not to support the EKC hypothesis, which postulates an inverted-U-shaped relationship.
Mostrar más [+] Menos [-]Characterization of earthworm α-amylases for dietary supplement development and biomass utilization Texto completo
2020
Akazawa, Shin-ichi | Ikarashi, Yuki | Yokoyama, Keisuke | Shida, Yosuke | Ogasawara, Wataru
Earthworms are useful soil-decomposing animals that possess various saccharification enzymes such as cellulases and amylases. Earthworms have also been traditionally used as antipyretic agents and medicines for preventing thrombotic diseases such as brain infarction. We previously developed a novel earthworm dietary supplement with fibrinolytic, cellulase, and amylase activities using high-pressure technology. However, the optimal temperature and pH required for amylase activity in bioindustry have not yet been investigated. In the present study, we purified and characterized two α-amylases of Eisenia fetida Waki, EfAMY1 and EfAMY2, which were monomeric enzymes of 63.8 kDa and 64.0 kDa, with specific activities of 69.2 and 40.4 units/mg, respectively. The optimal pH was 5.5 for both enzymes, and the optimal temperatures were 45 °C and 35 °C for EfAMY1 and EfAMY2, respectively; however, the enzymes were stable over a wide pH range (5–10) and at high temperature (up to 40 °C). These amylases showed higher specific activity and cold tolerance than those previously reported. These data should help to promote the development of E. fetida AMYs as functional dietary supplements and in biomass utilization.
Mostrar más [+] Menos [-]Characterization of bimetallic Fe/Ni nanoparticles supported by amphiphilic block copolymer and its application in removal of 1,1,1-trichloroethane in water Texto completo
2020
Huang, Kai | Bian, Hao | Zhang, Meng | Zhan, Cong | Li, Can | Zhang, Wei | Cui, Changzheng | Lu, Qiang | Lin, Kuangfei | Zhao, Jianhua
The iron and nickel bimetallic nanoparticles supported by the block copolymer polystyrene-block-poly (acrylic acid) (PS-b-PAA-nZVI-Ni) were synthesized successfully and were applied to assess the degradation of 1,1,1-trichloroethane (1,1,1-TCA) in water. An optimal dose of Ni loading was 2 wt%, while an optimal mass ratio of PS-b-PAA to Ni/Fe, i.e., 0.5:1, at which the dechlorination efficiency was a maximum. The size of PS-b-PAA-nZVI-Ni nanoparticles (average size ~ 50 nm) was three times smaller than that of nZVI-Ni due to the prevention of agglomeration of the resultant zerovalent iron nanoparticles by PS-b-PAA. In the applying aspect, the pseudo-first-order rate constant (Kₒbₛ) of 1,1,1-TCA removal by PS-b-PAA-nZVI-Ni was 0.0142 min⁻¹ within 240 min, which was approximately five times higher than nZVI. Meanwhile, PS-b-PAA-supported nZVI-Ni nanoparticles penetrated much deeper in quartz sand columns than nZVI-Ni nanoparticles, indicating PS-b-PAA had significant influence on nZVI transport. The findings from this study suggested that PS-b-PAA-nZVI-Ni, with its high reactivity, selective screening for 1,1,1-TCA, could be one significant potential for use as remedial agent to treat chlorinated solvents in water.
Mostrar más [+] Menos [-]Innovative health risk assessments of heavy metals based on bioaccessibility due to the consumption of traditional animal medicines Texto completo
2020
Zuo, Tian-Tian | Qu, Hao-Ran | Jin, Hong-Yu | Zhang, Lei | Luo, Fei-Ya | Yu, Kun-Zi | Gao, Fei | Wang, Qi | Sun, Lei | He, Huai-Zhen | Ma, Shuang-Cheng
Few studies reported the extent of heavy metal accumulation in traditional Chinese medicines (TCMs). Currently, oral bioaccessibility of lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), and copper (Cu) present in traditional animal medicines was investigated with physiologically based extraction test–extracted in vitro model. We are the first to develop a health risk assessment strategy by combinational analysis of bioaccessible heavy metal levels to calculate target hazard quotient (THQ), target hazard index (THI) and cancer risk (CR), which has capacity to evaluate the heavy metal associated heath risk of traditional animal medicines. To precisely acquire a realistic risk assessment, questionnaire data was adopted to measure the frequency and duration of the exposure to traditional animal medicines, and the safety factor was highlighted as well. Our data revealed that the bioaccessibility of Hg was the lowest among the five heavy metals. After the adjustment with the bioaccessibility of each heavy metal to target hazard index (THI) values, excitingly, the results manifested that the consumption of traditional animal medicines might not exert an unacceptable health risk in a broad community. In addition, the CR values of As and Pb indicated that the risk of developing cancers was quite lower than their acceptable levels in the clinic.
Mostrar más [+] Menos [-]The impact of age-related sub-chronic exposure to chlorpyrifos on metabolic indexes in male rats Texto completo
2020
Samarghandian, Saeed | Foadoddin, Moshen | Zardast, Mahmoud | Mehrpour, Omid | Sadighara, Parisa | Roshanravan, Babak | Farkhondeh, Tahereh
Chlorpyrifos (CPF), an organophosphorus pesticide (OP), has been implicated in metabolic diseases; however, the data are controversial. Rising age has been found as a main risk factor for metabolic diseases, and it has been proposed that advanced age increases susceptibility to the toxic effects of OPs. Therefore, this investigation aimed to evaluate the impact of CPF on hyperglycemia, hypercholesterolemia, and inflammation in animals with different ages. CPF (5 mg/kg) for 45 consecutive days was administered orally to male Wistar rats with different ages including 2-, 10-, and 20-month-old. The results indicated an increase in glucose and inflammatory indices, and also lipid profile was changed in the serum of aged animals in comparison with the 2-month-old animals. CPF administration amplified these parameters in the 20-month-old rats in comparison with that of aged-matched controls. The histopathological examination also indicated that CPF caused slight to moderate changes in the liver of 2-, 10-, and 20-month-old animals. Cholestasis was also observed in the CPF-administrated 20-month-old rats. In conclusion, aging may increase the susceptibility to CPF-induced metabolic disturbances in the animal models. It is proposed that advancing in age elevates the susceptibility to the metabolic effects of CPF.
Mostrar más [+] Menos [-]Evaluation of bisphenol A levels in Nigerian thermal receipts and estimation of daily dermal exposure Texto completo
2020
Adeyemi, Joseph A. | Gallimberti, Matheus | Olise, Christian C. | Rocha, Bruno Alves | Adedire, Chrs O. | Barbosa Jr, Fernando
Bisphenol A (BPA) is a high production volume chemical that has wide industrial applications, especially as a color developer in thermal papers. The present study focused on the determination of levels of BPA in thermal receipts collected from different locations in Akure, Nigeria, and the estimation of daily intake of BPA through dermal absorption. Thermal receipts were collected from different locations, and the levels of extracted BPA were determined using fluorescence spectroscopy. The daily intake of BPA was estimated, and the amount was compared with the reference value. BPA was detected in all the samples analyzed with levels ranging from 1.50 to 3.16 mg/g. These values were lower than the values detected in thermal receipts obtained from other countries. The estimated mean daily intakes of BPA by dermal absorption due to handling of thermal receipts were 0.20 and 9.89 μg/day for the general population and the occupationally exposed individuals, respectively, and were much lower than the reference value of 50 μg/kg bw/day provided by the European Food Safety Authority. This indicates that dermal exposure to BPA is not a serious health risk to the population.
Mostrar más [+] Menos [-]Enhancing Salix viminalis L.–mediated phytoremediation of polycyclic aromatic hydrocarbon–contaminated soil by inoculation with Crucibulum laeve (white-rot fungus) Texto completo
2020
Ma, Xiaodong | Li, Xia | Liu, Junxiang | Cheng, Yunhe | Zhai, Feifei | Sun, Zhenyuan | Han, Lei
Although plant-white-rot fungi (WRF) remediation is considered efficient in improving polycyclic aromatic hydrocarbon (PAH)–contaminated soil, the prospects for using it remain poorly known. Therefore, we evaluated whether the WRF Crucibulum laeve could improve the phytoremediation of PAH-contaminated soil by Salix viminalis L. A 60-day pot experiment was conducted to investigate the effects of C. laeve inoculation (using two inoculation treatments and a non-inoculated control) on the phytoremediation potential, growth, and antioxidant metabolism of S. viminalis cultivated in PAH-contaminated soil. The S. viminalis-C. laeve association synergistically caused the highest PAH removal rate. Under the S. viminalis-C. laeve treatment, 80% of the biological concentration and translocation factors for all tissues of S. viminalis were > 1, whereas only 20% of these factors were > 1 when S. viminalis was used alone. C. laeve inoculation remarkably enhanced phytoremediation by promoting S. viminalis–based phytoextraction of PAHs from soils. Furthermore, although C. laeve inoculation altered the antioxidant metabolism of S. viminalis by inducing oxidative stress, thereby inhibiting plant growth, the plant’s hardiness enabled it to survive and grow normally for 60 days after treatment. Therefore, phytoremediation using S. viminalis inoculated with C. laeve can be considered a feasible approach for the phytoremediation of PAH-contaminated soil.
Mostrar más [+] Menos [-]Smoke-free workplaces are associated with smoke-free homes in India: evidence for action Texto completo
2020
Tripathy, Jaya Prasad
India enacted a smoke-free law in 2003. It is believed that smoke-free workplaces will lead to more smoking in private places such as homes. The national Global Adult Tobacco Survey (GATS 2) India 2016–2017 collects information on the self-reported prevalence of SHS exposure in homes and workplaces. The present study utilised the GATS 2 dataset to establish the association between working in a smoke-free workplace and living in a smoke-free home. 70.1% of respondents who worked indoors reported smoke-free workplace; 64.5% of respondents reported that they live in a smoke-free home. Respondents who reported that their workplace was smoke-free were significantly more likely to live in smoke-free homes compared with those who are exposed to SHS at the workplace (69.5% vs 45.5%, AOR = 1.8, 95% CI 1.5–2.1). Males, urban residents, family with fewer members, non-smokers and non-smokeless tobacco users were significantly more likely to live in a smoke-free home. Significant differences were also observed with respect to religion, caste, region and education levels. Our results provide conclusive evidence to support that smoke-free workplaces influence smoke-free homes in India. Thus, it highlights the importance of accelerating the implementation of existing national tobacco control legislation on smoke-free public places.
Mostrar más [+] Menos [-]Effects of di (2-ethylhexyl) phthalate and high-fat diet on lipid metabolism in rats by JAK2/STAT5 Texto completo
2020
Zhang, Yuezhu | Zhou, Liting | Zhang, Zhaoming | Xu, Qi | Han, Xu | Zhao, Yaming | Song, Xinyue | Zhao, Tianyang | Ye, Lin
Exposure to di (2-ethylhexyl) phthalate (DEHP) induces lipid metabolism disorder and high-fat diet (HD) may have joint effects with DEHP. We aim to clarify the role of JAK2/STAT5 pathway in the process and reveal the effects of HD on the toxicity of DEHP. Wistar rats (160 animals) were fed with HD or normal diet (ND) respectively and exposed to DEHP 0, 5, 50, and 500 mg/kg/day for 8 weeks. Lipid levels, as well as the morphology of liver and adipose, mRNA levels, and protein levels of JAK2, STAT5A, STAT5B, FAS, ap2, and PDK4 were detected. The results showed that DEHP exposure leads to increased weight gain. The JAK2/STAT5 pathway was activated in adipose after DEHP exposure and promoted the expression of FAS, ap2, and PDK4 in ND rats. While in the liver, JAK2 was inhibited, and lipid synthesis and accumulation were increased. However, rats exposed to DEHP in combination with HD showed a complete disorder of lipid metabolism. Therefore, we conclude that DEHP affects lipid metabolism through regulating the JAK2/STAT5 pathway and promotes adipogenesis and lipid accumulation. High-fat diet may have a joint effect with DEHP on lipid metabolism disorder.
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