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Atmospheric chemistry of CF2ClO2: a theoretical study on mechanisms and kinetics of the CF2ClO2 + HO2 reaction 全文
2020
Zhang, Yunju | He, Bing | Wang, Zhiguo | Huang, Baomei | Zhou, Yan
The singlet and triplet potential energy surfaces of the HO₂ with CF₂ClO₂ reaction have been probed at the BMC-CCSD/cc-pVTZ level according to the B3LYP/6-311++G(d,p) level obtained geometrical structure. On the singlet PES, the association/dissociation, direct H- abstraction, and SN2 displacement mechanisms have been taken into account. On the triplet PES, SN2 displacement and indirect H- abstraction reaction mechanisms have been investigated and the H- abstraction channel makes more contribution to the CF₂ClO₂ with HO₂ reaction. The rate constants have been computed at 10⁻¹⁰ to 10¹⁰ atm and 200–3000 K by RRKM-TST theory. The results show that at T ≤ 600 K, the generation of IM1 (CF₂ClO₄H) by collisional deactivation is dominant pathway; at high temperatures, the production of P8 (CF₂ClOOH + O₂(³Σ)) becomes predominate. The predicted data for CF₂ClO₂ + HO₂ agrees closely with available experimental value. Moreover, OH radicals act as inhibitors in the CF₂ClOOH→CF₂O + HOCl and CF₂ClOOH→CFClO + HOF reactions. The dominant products for the reaction of CF₂ClOOH + OH are CF₂ClO₂ + H₂O.
显示更多 [+] 显示较少 [-]LINC01133: an emerging tumor-associated long non-coding RNA in tumor and osteosarcoma 全文
2020
Li, Zheng | Xu, Derong | Chen, Xin | Li, Shugang | Chan, Matthew T. V. | Wu, William K. K.
Emerging evidence suggested that long non-coding RNAs (lncRNAs) play pivotal roles in tumorigenesis. LINC01133 is a newly identified lncRNA first discovered as an oncogene in lung squamous cell carcinoma. Subsequent studies further demonstrated this lncRNA was deregulated in a wide spectrum of tumors, including colorectal, gastric, lung, and pancreatic ductal adenocarcinoma as well as osteosarcoma and hepatocellular carcinoma. Intriguingly, this lncRNA exerted oncogenic or tumor-suppressive action in a tissue-dependent manner. This review sought to summarize our current understanding concerning the deregulation of LINC01133 in human tumors in relation to its molecular mechanisms and cellular functions. The clinical utilization of LINC01133 as a potential prognostic biomarker and a treatment target is also discussed.
显示更多 [+] 显示较少 [-]Removal of heavy metals and radionuclides from water using nanomaterials: current scenario and future prospects 全文
2020
Kumar, Vinod | Katyal, Deeksha | Nayak, SwayangSiddha
There is an increase in concern about the hazardous effects of radioactivity due to the presence of undesirable radioactive substances in our vicinity. Nuclear accidents such as Chernobyl (1986) and Fukushima (2011) have further raised concerns towards such incidents which have led to contamination of water bodies. Conventional methods of water purification are less efficient in decontamination of radioisotopes. They are usually neither cost-effective nor environmentally friendly. However, nanotechnology can play a vital role in providing practical solutions to this problem. Nano-engineered materials like metal oxides, metallic organic frameworks, and nanoparticle-impregnated membranes have proven to be highly efficient in treating contaminated water. Their unique characteristics such as high adsorption capacity, large specific surface area, high tensile strength, and excellent biocompatibility properties make them useful in the field of water purification. This review explores the present status and future prospects of nanomaterials as the next-generation water purification systems that can play an important role in the removal of heavy metals and radioactive contaminants from aqueous solutions.
显示更多 [+] 显示较少 [-]Impact of environmental regulation on green growth in China’s manufacturing industry–based on the Malmquist-Luenberger index and the system GMM model 全文
2020
Cao, Yaru | Liu, Jun | Yu, Yu | Wei, Guo
Green growth in manufacturing is critical to the sustainable development of manufacturing, and environmental regulations can help ensure green growth. The impact of environmental regulations on China’s manufacturing industry sectors is investigated to further green development in manufacturing. Using panel data for manufacturing industry sectors from 2008 to 2015, the Malmquist-Luenberger index model is employed to calculate green growth efficiency and an econometric model is constructed to measure the impact of environmental regulations on green growth. By using the system generalized method of moments (system GMM) model and other panel estimation models to generate regression results, it is found that environmental regulation exhibits a U-shaped nonlinear influence on green growth; as the intensity of environmental regulations increases, there is an initial inhibiting effect followed a positive impact on green growth in the manufacturing industry. Once environmental regulation intensity reaches a certain level, it mainly promotes green growth through technological progress. Further findings include the following: impacts of environmental regulation on green growth are heterogeneous across industries, and effects (e.g. U-shaped impacts) are most significant among high-energy industries, high-pollution industries, and medium-pollution industries.
显示更多 [+] 显示较少 [-]The impact of tourism and natural resources on the ecological footprint: a case study of ASEAN countries 全文
2020
Kongbuamai, Nattapan | Bui, Quocviet | Yousaf, Hafiz Muhammad Abaid Ullah | Liu, Yun
This study examines the impacts of economic growth, energy consumption, tourism, and natural resources on the ecological footprint in the ASEAN countries for spanning from 1995 to 2016. For this purpose, the cross-sectional dependent test, the second-generation unit root test, and the Westerlund cointegration test have been applied. The Driscoll-Kraay panel regression model has been used to check the long-run relationship among the series. Also, the Dumitrescu-Hurlin panel causality test is used to determine the paths of causal interactions. These tests help to overcome the problem of cross-sectional dependence in panel data analysis. The results showed an inverted U-shaped EKC behavior in ASEAN countries, hence a negative relation between tourism and natural resources with the ecological footprint. This implies that tourism and natural resources help to improve the environmental quality in ASEAN countries.
显示更多 [+] 显示较少 [-]TCEs and environmental research: is the TCEs concept scientifically fruitful? 全文
2020
Filella, Montserrat
TCEs stands for technology-critical elements, a group of chemical elements for which imbalances between supply and demand exist or are deemed probable. This article challenges the scientific usefulness of such a classification when dealing with environmental and toxicological issues. Criticality is an economic conceptualization that is not well suited to guiding environmental chemistry research efforts. The classification is even counterproductive because it does not foster collaborative research with the countries directly touched by the environmental problems which are directly linked to the production of the elements.
显示更多 [+] 显示较少 [-]Identification of drug resistance genes and drug resistance analysis of Salmonella in the duck farm environment of Zhanjiang, China 全文
2020
Niu, Jin-Li | Peng, Jin-Ju | Ming, Yue-Yue | Ma, Qi-Chao | Liu, Wen-Chao | Ma, Yi
This study investigated and identified the distribution of drug resistance genes in feces, soil, and water of duck farms in Zhanjiang, China, and analyzed the drug resistance of Salmonella in the duck farm environment. PCR was used to assess the distribution of 25 resistance genes that are common in the duck farm environment. The isolation, biochemical identification, PCR identification of Salmonella, and the minimum inhibitory concentration (MIC) of 22 drugs were measured by micro-broth double dilution. In water, 25 drug resistance genes were detected, 24 in soil, and 23 in feces. Among them, the detection rate of the aadA1 gene in soil reached 100%, 13 drug resistance genes had a detection rate above 80%, and five species had a detection rate below 50%. In water, the detection rate of the floR and aadA1 genes was 100%, 12 drug resistance genes had a detection rate above 80%, and eight genes had a detection rate below 50%. In feces, nine drug resistance genes had a detection rate of 100%, nine genes had a detection rate above 80%, and one gene had a detection rate below 50%. In addition, 92 strains of Salmonella were isolated and identified, and their resistance rate to nine drugs was as high as 100%. All isolated Salmonella can tolerate at least nine drugs, 55.43% (51/92) of the strains can tolerate more than 16 drugs, and 4.35% (4/92) of the strains were resistant to up to 21 drugs. In conclusion, the present experiment suggested that drug resistance genes were ubiquitous in the duck farm environment in Zhanjiang and that these drug resistance genes may spread horizontally between feces, soil, and water. Moreover, drug resistance and multi-drug resistance were found for 92 isolated Salmonella strains from the duck farm environment. The government should consequently strengthen the regulation of antimicrobial drug use in duck farms.
显示更多 [+] 显示较少 [-]Conversion of cotton textile wastes into porous carbons by chemical activation with ZnCl2, H3PO4, and FeCl3 全文
2020
Xia, Meiling | Shao, Xiaohou | Sun, Zhenhua | Xu, Zhihua
In this study, ZnCl₂, H₃PO₄, and FeCl₃ were used as activating agents to prepare porous carbons (PC-ZnCl₂, PC-H₃PO₄, and PC-FeCl₃) from cotton textile wastes at a relativity low temperature. The morphology and structure of carbons were characterized by SEM and XRD demonstrating that carbons with porous property were successfully obtained. Textural properties showed that the PC-ZnCl₂ possessed the largest specific surface area of 1854.70 m² g⁻¹ with mesopores domination. Both of micropores and mesopores existed in PC-H₃PO₄. Micropores were well developed in PC-FeCl₃, and the proportion of which was the highest. The FTIR and pHₚzc analysis indicated that all the carbons had acidic characteristics, and more acid functional groups were appeared on the PC-FeCl₃ than others. The different pyrolysis activation paths were proposed by the thermogravimetric analysis, which proved that the addition of activating agents promoted the formation of pores, lowered the pyrolysis temperature of cotton textile wastes, and inhibited the production of volatiles. The results of adsorption kinetics and isotherm revealed that PC-ZnCl₂ exhibited the best adsorption capacity of Cr(VI), and chemical adsorption played a significant role. Meanwhile, surface functional groups of porous carbons also participated in the Cr(VI) adsorption via electrostatic interaction and reduction reaction. Graphical abstract
显示更多 [+] 显示较少 [-]Effects of EDDS on the Cd uptake and growth of Tagetes patula L. and Phytolacca americana L. in Cd-contaminated alkaline soil in northern China 全文
2020
Wang, Yale | Xu, Yingming | Qin, Xu | Liang, Xuefeng | Huang, Qingqing | Peng, Yunying
Phytoextraction has been considered an effective and environment-friendly method for removing heavy metals from contaminated soil. However, the efficiency, mechanism, and adaptability of phytoextraction by hyperaccumulators in Cd-polluted weakly alkaline soil have not been investigated in detail. In this study, pot experiments were conducted to evaluate the enhanced effects of S,S-ethylenediamine disuccinic acid (EDDS) on phytoextraction in alkaline soil by measuring the degradation kinetic characteristics of EDDS and Cd absorption dynamics of Tagetes patula L. (T. patula) and Phytolacca americana L. (P. americana) for a period of 55 days. Results showed that the half-life of EDDS varied from 4.20–7.07 days and 3.35–4.36 days for T. patula and P. americana, respectively. EDDS-activated Cd reached saturation at a low dosage (1 mM) and a single application of EDDS was found to be better than double applications. The activation of EDDS on Cd applied before 45 days of harvest was better than that before 15 days of harvest, and disappeared after a 35-day application. Correspondingly, the Cd concentration in P. americana and T. patula leaves increased significantly after 3 days of the EDDS application. However, T. patula had a biomass 2.57 times and Cd absorption capacity 10.06 times higher than P. americana. EDDS showed almost no influence on the stem and leaf biomass of T. patula; however, the root weight decreased by 9.44–71.77%. The Cd concentration in T. patula leaves of all the treatments was 1.00–1.81 times that of the control group. In comparison with other treatments, the EDDS application (3 mM) before 15 days of harvest extracted the highest amount of Cd (601.45 μg/pot) in T. patula shoots, reaching 1.40 times that in the control group. Therefore, T. patula might be a more suitable phytoremediator for Cd-polluted alkaline soil than P. americana; the most effective method was the EDDS application (3 mM) before 15 days of harvest.
显示更多 [+] 显示较少 [-]Field observation and simulation experiments on nutrient transformation during phytoplankton-derived particulate matter deposition 全文
2020
Kong, Ming | Liu, Cheng | Chao, Jianying | Wang, Longmian | Gao, Yuexiang | Peng, Fuquang | Xu, Xueting | Han, Tianlun | Wang, Peifang | Wang, Chao
Phytoplankton-derived particulate matter (PPM) is the active component of the solid particles in eutrophic shallow lakes. To date, understanding of the degradation characteristics of PPM and the effect of degradation products on nutrient cycling in water are limited. In this study, field observations and simulation experiments were carried out to elaborate the nutrient transformation during phytoplankton-derived particulate matter deposition in the cyanobacterial blooming area of Lake Taihu. Results showed that the deposition of the PPM was strongly facilitated by the cyanobacterial bloom and the sediment resuspension. The main variation characteristics of phosphorus (P) species in PPM are shown in the increase of Ortho-P and the decrease of biodegradable phosphorus (Poly-P, DNA-P) during the deposition of PPM. The degradation of the PPM resulted in the release of dissolved nitrogen (N) and P to the water body. The conversion of easily degradable particulate N and P in the PPM to ammonium nitrogen (NH₃-N) and soluble reactive phosphorus were believed to be responsible for this phenomenon. The cycling of nutrients and the cyanobacterial bloom status might therefore be altered because of the deposition and degradation of PPM. More considerations should be given on this process in future works.
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