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The influence of lattice deformation on the elastic properties of Mg_2Si

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Science China(Physics,Mechanics & Astronomy) 2013年第4期56卷 701-705页

作者： CHEN Qian xie quan XIAO Qingquan ZHANG JinMin College of Science Guizhou University Institute of New Optoelectronic Materials and Technology Guizhou University

A detailed theoretical study of the structural and elastic properties of magnesium silicide Mg2 Si under isotropic lattice deformation has been performed based on the first-principles' pseudopotential method. The results show that isotropic lattice deformation from 94% to 106% results in a linear decrease in the energy gap for the direct Г15-Г1 and indirect Г15-L1 transitions, while the indirect band gap Г15 -X1 increases within a range of 94%-104%, and then reduces over the range of 104%. Additionally, isotropic lattice deformation from 94% to 106% also causes a decrease in the elastic constants and modulus of Mg2 Si. Furthermore, Mg2 Si with lattice deformation from 94% to 106% is brittle, being most brittle at 94% lattice constant.

关键词： magnesium silicide lattice deformation first-principles band structure elastic properties

Microstructural Transitions during the Rapid Cooling Process of Liquid Metal Al

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Journal of Materials Science & Technology 1998年第5期14卷 461-464页

作者： Li, Jiyong Liu, Rangsu xie, quan Peng, Ping Zhou, Zheng Hunan Univ Dept Chem Changsha 410012 Peoples R China Hunan Univ Dept Phys Changsha 410012 Peoples R China

From a molecular-dynamics simulation study, it was demonstrated that the microscopic structure transitions is mainly determined by the changes of various microstructural configurations. There are two obvious phase transition points during the rapid cooling process. The first transition point is consistent with the well-known glass transition. The second one is a new weaker transition at low temperature. The cluster having 7-fold symmetry still exist in the supercooled liquid metal Al, though it occupies only 0.1% of the total number of clusters in the system and disappears below 550 K, namely, it can not exist in the glassy state. These results will give us a new way to understand the structural transition at microscopic level. (Edited author abstract) 15 Refs.

关键词： Aluminum

Effects of Cu(Ⅱ) and humic acid on atrazine photodegradation

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Journal of Environmental Sciences 2011年第5期23卷 773-777页

作者： Xia Sun Hui Liu Yaobin Zhang Yazhi Zhao xie quan Key Laboratory of Industrial Ecology and Environmental Engineering Ministry of Education Department of Environmental Science and Technology Dalian University of Technology Dalian 116024 China. E-mail: zhangyb@***

This work was designed to explore the characteristics of photodegradation of herbicides in the copper-polluted water body. The results showed that Cu（Ⅱ） alone could induce a photo Fenton-like reaction to enhance the degradation of atrazine, in which hydroxyl radical （.OH） was a main active species. Humic acids restrained atrazine degradation, nevertheless, when introducing Cu（Ⅱ）, the photodegradation was accelerated, in which singlet oxygen （102） replaced -OH acting as the prevailing species. A feasible mechanism for the photochemical process was also proposed, which is helpful for better understanding the environmental photochemistry of atrazine in the copper-polluted water.

关键词： humic acids Cu(Ⅱ) photodegradation hydroxyl radical singlet oxygen

Preparation of Zn-doped TiO_2 nanotubes electrode and its application in pentachlorophenol photoelectrocatalytic degradation

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Chinese Science Bulletin 2007年第11期52卷 1456-1461页

作者： ZHAO HuiMin CHEN Yue quan xie RUAN XiuLi Key Laboratory of Industrial Ecology and Environmental Engineering Ministry of Education School of Environmental and BiologicalScience and Technology Dalian University of Technology Dalian 116024 China

Zn-doped titanium oxide (TiO2) nanotubes electrode was prepared on a titanium plate by direct anodic oxidation and immersing method in sequence. Field emission scanning electron microscopy (FESEM) showed that the Zn-doped TiO2 nanotubes were well aligned and organized into high density uniform arrays with diameter ranging from 50 to 90 nm. The length and the thickness were about 200 and 15 nm respectively. TiO2 anatase phase was identified by X-ray diffraction (XRD). X-ray photoelectronspec-troscopy (XPS) indicated that Zn ions were mainly located on the surface of TiO2 nanotubes in form of ZnO clusters. Compared with TiO2 nanotubes electrode,about 20 nm red shift in the spectrum of UV-vis absorption was observed. The degradation of pentachlorophenol (PCP) in aqueous solution under the same condition (initial concentration of PCP: 20 mg/L; concentration of Na2SO4: 0.01 mol/L and pH: 7.03) was carried out using Zn-doped TiO2 nanotubes electrode and TiO2 nanotubes electrode. The degradation rates of PCP using Zn-doped TiO2 nanotubes electrode were found to be twice and 5.8 times as high as that using TiO2 nanotubes electrode by UV radiation (400 μw/cm2) and visible light radiation (4500 μw/cm2),respectively. 73.5% of PCP was removed using Zn-doped TiO2 nanotubes electrode against 48.5% removed using TiO2 nanotubes electrode in 120 min under UV radiation. While under visible light radiation,the degradation efficiency of PCP was 18.4% using Zn-doped TiO2 nano-tubes electrode against 3.2% using TiO2 nanotubes electrode in 120 min. The optimum concentration of Zn doping was found to be 0.909%. The PCP degradation efficiencies of the 10 repeated experiments by Zn-doped TiO2 nanotubes electrode were rather stable with the deviation within 3.0%.

关键词： TiO2 电极杂质锌光电接触五氯苯酚

Effective adsorption of 2,4-dichlorophenol on hydrogenated graphene: kinetics and isotherms

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Chinese Science Bulletin 2014年第34期59卷 4752-4757页

作者： Hui Yuan Hongtao Yu Xiaona Li xie quan Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) School of Environmental Science and Technology Dalian University of Technology

The effective adsorption capability of a hydrogenated graphene(H-Gr) was demonstrated. The H-Gr was firstly prepared by heating graphene(Gr) in a hydrogen flow at 1,000 °C. The specific surface area, layer number, zeta potential, surface defects, surface compounds groups and elemental ratio of H-Gr were *** 2,4-dichlorophenol as a target pollutant, the adsorption ability of H-Gr was evaluated. The results showed that the adsorption kinetics followed the pseudosecond-order equation well. For the adsorption isotherms,the equilibrium data of H-Gr were found to fit to Langmuir model, which was different from the Freundlich model of Gr. The adsorption capacity of H-Gr was high to287.01 mg/g, almost three times as much as that of Gr,which was benefit from the increase of specific surface area and zeta potential. This work suggests that H-Gr may be a potential candidate for the adsorption of aromatic compounds from water and has great prospect for practical application.

关键词：吸附能力吸附动力学吸附等温线二氯苯酚石墨氢化 Freundlich模型 Langmuir模型

Contribution of black carbon to nonlinearity of sorption and desorption of acetochlor on sediment

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Frontiers of Environmental Science & Engineering 2009年第1期3卷 69-74页

作者： Jianqiu LIU Yaobin ZHANG Hong CHEN Yazhi ZHAO xie quan Key Laboratory of Industrial Ecology and Environmental Engineering Ministry of EducationSchool of Environmental and Biological Science and TechnologyDalian University of TechnologyDalian 116023China

In order to investigate the contribution of various black carbon(BC)contents to nonlinearity of sorption and desorption isotherms for acetochlor on sediment,equilibrium sorption and desorption isotherms were determined to measure sorption and desorption of acetochlor in sediment amended with various amounts of *** this paper,two types of BC referred to as BC400 and BC500 were prepared at 400℃ and 500℃,*** preparation temperature facilitated the formation of micropores on BC to enhance its sorption *** of the BC content obviously increased the sorption amount and reduced the desorption amount for *** the BC500 contents in total organic carbon(TOC)increased from 0 to 60%,Freundlich sorption coefficient(K_(f))increased from 4.07 to 35.74,and desorption hysteresis became gradually *** the content of BC in TOC was lower than 23%,the sorption isotherm had a significant linear correlation(p=0.05).In case of desorption,a significant nonlinear change could be observed when the content of BC was up to 13%.Increase of BC content in the sediment would result in shifting the sorption-desorption isotherms from linearity to nonlinearity,which indicated that contribution of BC to nonlinear adsorption fraction became gradually remarkable.

关键词： black carbon(BC) sorption desorption sediment

Enhanced anaerobic fermentation with azo dye as electron acceptor: Simultaneous acceleration of organics decomposition and azo decolorization

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Journal of Environmental Sciences 2014年第10期26卷 1970-1976页

作者： Yang Li Yaobin Zhang xie quan Jingxin Zhang Shuo Chen Shahzad Afzal Key Laboratory of Industrial Ecology and Environmental Engineering Ministry of Education School of Environmental Science and TechnologyDalian University of Technology

Accumulation of hydrogen during anaerobic processes usually results in low decomposition of volatile organic acids（VFAs）. On the other hand, hydrogen is a good electron donor for dye reduction, which would help the acetogenic conversion in keeping low hydrogen concentration. The main objective of the study was to accelerate VFA composition through using azo dye as electron acceptor. The results indicated that the azo dye serving as an electron acceptor could avoid H2 accumulation and accelerate anaerobic digestion of VFAs. After adding the azo dye, propionate decreased from 2400.0 to 689.5 mg/L and acetate production increased from 180.0 to 519.5 mg/L. It meant that the conversion of propionate into acetate was enhanced. Fluorescence in situ hybridization analysis showed that the abundance of propionate-utilizing acetogens with the presence of azo dye was greater than that in a reference without azo dye. The experiments via using glucose as the substrate further demonstrated that the VFA decomposition and the chemical oxygen demand（COD） removal increased by 319.7 mg/L and 23.3% respectively after adding the azo dye. Therefore, adding moderate azo dye might be a way to recover anaerobic system from deterioration due to the accumulation of H2 or VFAs.

关键词： Azo dye Anaerobic treatment Volatile fatty acids H2accumulation

Impact of dissolved organic matter on the photolysis of the ionizable antibiotic norfloxacin

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Journal of Environmental Sciences 2015年第1期27卷 115-123页

作者： Chen Liang Huimin Zhao Minjie Deng xie quan Shuo Chen Hua Wang Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) School of Environmental Science and TechnologyDalian University of Technology College of Fisheries and Life Science Dalian Ocean University

Norfloxacin（NOR）, an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ***, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter（DOM）, which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance（EPR） were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical（U OH） and singlet oxygen（1O2） based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of U OH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and1O2. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored.

关键词： Norfloxacin(NOR) Dissolved organic matters(DOM) Dissociated species Photolysis Aquaculture industry

Removal of multicomponent VOCs in off-gases from an oil refining wastewater treatment plant by a compost-based biofilter system

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Frontiers of Environmental Science & Engineering 2009年第4期3卷 483-491页

作者： Dan WU Chunyan ZHANG Changjun GENG Li HAO xie quan School of Environmental Science Liaoning UniversityShenyang 110036China School of Environmental and Biological Science and Technology Dalian University of TechnologyDalian 116024China Research Institute of Daqing Petrochemical Company Daqing 163714China

Waste gases from oil refining wastewater treatment plants are often characterized by the presence of multicomponent and various concentrations of *** evaluation of the performance and feasibility of removing multicomponent volatile organic compounds(VOCs)in off-gases from oil refining wastewater treatment plants was conducted in a pilot-scale compost-based biofilter *** system consists of two identical biofilters packed with compost and polyethylene(PE).This paper investigates the effects of various concentrations of nonmethane hydrocarbon(NMHC)and empty bed residence time(EBRT)on the removal efficiency of *** on the experimental results and practical applications,an EBRT of 66 s was applied to the biofilter *** removal efficiencies of NMHC were within the range of 47%–100%.At an EBRT of 66 s,the average removal efficiency of benzene,toluene,and xylene were more than 99%,99%,and 100%,*** results demonstrated that multicomponent VOCs in off-gases from the oil refining wastewater treatment plant could be successfully removed in the biofilter system,which may provide useful information concerning the design criteria and operation of full-scale biofilters.

关键词： biodegradation volatile organic compounds(VOCs) biofiltration biofilter