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Search Results: 1 - 10 of 50876 matches for " Dongbin Wei "
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Evolution of Internal Crack in BCC Fe under Compressive Loading  [PDF]
Dongbin Wei, Zhengyi Jiang, Jingtao Han
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.310197
Abstract: A molecular dynamics model has been developed to investigate the evolution of the internal crack of nano scale during heating or compressive loading in BCC Fe. The initial configuration does not contain any pre-existing dislocations. In the case of heating, temperature shows a significant effect on crack evolution and the critical temperature at which the crack healing becomes possible is 673 K. In the case of compressive loading, the crack can be healed at 40 K at a loading rate 0.025 × 1018 Pa·m1/2/s in 6 × 10-12 s. The diffusion of Fe atoms into the crack area results in the healing process. However, dislocations and voids appear during healing and their positions change continuously.
Toxicity-based assessment of the treatment performance of wastewater treatment and reclamation processes
Dongbin Wei,Zhuowei Tan,Yuguo Du,
Dongbin Wei
,Zhuowei Tan,Yuguo Du

环境科学学报(英文版) , 2012,
Abstract: The reclamation and reuse of wastewater is one of the possible ways to relieve the serious fresh water resource crisis in China. Efficient reclamation treatment technologies ensure the safe reuse of reclaimed water. In order to screen out and evaluate technologies appropriate for reclamation treatment, a great deal of efforts have been brought to bear. In the present study, a toxicity-based method including a Photobacterium phosphoreum test for acute toxicity and SOS/umu test for genotoxicity, accompanied by the traditional physicochemical parameters DOC (dissolved organic carbon) and UV254 (absorbance at 254 nm), was used to measure the treatment performance of different reclamation processes, including the anaerobic-anoxic-oxic biological process (A2O) and subsequent physical/chemical reclamation processes (ultrafiltration, ozonation, chlorination). It was found that for the secondary effluent after the A2O process, both the toxicity and physicochemical indices had greatly decreased compared with those of the influent. However, chemical reclamation processes such as ozonation and chlorination could possibly raise toxicity levels again. Fortunately, the toxicity elevation could be avoided by optimizing the ozone dosage and using activated carbon after ozonation. It was noted that by increasing the ozone dosage to 10 mg/L and employing activated carbon with more than 10 min hydraulic retention time, toxicity elevation was controlled. Furthermore, it was shown that pre-ozonation before activated carbon and chlorination played an important role in removing organic compounds and reducing the toxicity formation potential. The toxicity test could serve as a valuable tool to evaluate the performance of reclamation processes.
A biological safety evaluation on reclaimed water reused as scenic water using a bioassay battery
Dongbin Wei,Zhuowei Tan,Yuguo Du,
Dongbin Wei
,Zhuowei Tan,Yuguo Du

环境科学学报(英文版) , 2011,
Abstract: An assessment method based on three toxicity tests (algae growth inhibition, daphnia immobilization and larval fish toxicity) was used to screen the biological safety of reclaimed water which was reused as sole replenishment for scenic water system in a park (SOF Park) in northern China. A total of 24 water samples were collected from six sites of water system in the SOF Park in four different seasons. The results indicated that: (1) the reclaimed water directly discharged from a reclamation treatment plant near the SOF Park as influent of park had relatively low biological safety (all samples were ranked as C or D); (2) the biological safety of reclaimed water was improved greatly with the ecological reclamation treatment processes composing of artificial wetland system and followed oxidation pond system; (3) the biological safety of reclaimed water in the main lake of SOF Park kept at a health status during different seasons (all samples were ranked as A); (4) there was some certain correlation (R2 = 0.5737) between the sum of toxicity scores and dissolved organic carbon for the studied water samples. It was concluded that the assessment method was reliable to screen the safety of reclaimed water reused as scenic water, and the reclaimed water with further ecological purification processes such as artificial wetland and oxidation pond system can be safely reused as scenic water in park.
Characterization of dissolved organic matter fractions and its relationship with the disinfection by-product formation

ZHANG Hua,QU Jiuhui,LIU Huijuan,WEI Dongbin,

环境科学学报(英文版) , 2009,
Abstract: Dissolved organic matter (DOM) has been identified as precursor for disinfection by-product (DBPs) formation during chlorination. Recently, it has been demonstrated that the characteristics of DOM influence the DBPs formation mechanism. A study was, therefore, initiated to investigate the effects of DOM fractions on DBPs formation mechanism. In the chlorination process, organic acids are dominant precursors of total thihalomethanes (TTHM) because of the νC-O and unsaturated structures. Furthermore, the TTHM formation of organic acids was affected by pH more greatly. Based on the fluorescence spectroscopy analysis, DOM fractions contained several fluorescence substances. During chlorination, humic acid-like substances were found to exhibit high chlorine reactivity and hydrophobic organics decomposed to smaller molecules faster than hydrophilic organics even at lower chlorine dosages. Unlike hydrophobic fractions, hydrophilic organics showed no toxicity following chlorination, suggesting that the toxic structures in hydrophilic organics showed high chlorine reactivity during chlorination.
Removal of benzene homologous compounds with chlorine dioxide
Chen Hui,Wei Dongbin,
Chen Hui
,Wei Dongbin,Wang Shuyan,Zhu Mingyang,Liu Zhaochang,Keng Zhu

环境科学学报(英文版) , 1996,
Abstract: Chlorine dioxide composite disinfectant generator that produces a mixture of the oxidant gases comprising chlorine dioxide, chlorine, ozone and hydrogen peroxide through electrolyzing salt,is widely utilized in China presently.The experiments in the paper focused on the removal of benzene homologous compounds such as styrene, methyl and dimethyl benzene. The results indicated that pH value was the most crucial factor to influence the treatment effects while reaction time and input way were considered as the importance. The removal rate for benzene could reach 60% when above 80% for methyl, and 100% for styrene and dimethyl. The variation mechanisms between chlorine dioxide,chlorite and chloride which determine the drinking water quality also discussed.
Sequential use of ultraviolet light and chlorine for reclaimed water disinfection
Xiujuan Wang,Xuexiang Hu,Chun Hu,Dongbin Wei,
Xiujuan Wang
,Xuexiang Hu,Chun Hu,Dongbin Wei

环境科学学报(英文版) , 2011,
Abstract: Several disinfection processes of ultraviolet (UV),chlorine or UV followed by chlorine were investigated in municipal wastewater according to the inactivation of Escherichia coli,Shigella dysenteriae and toxicity formation.The UV inactivation of the tested pathogenic bacteria was not affected by the quality of water.It was found that the inactivated bacteria were obviously reactivated after one day in dark.Fluorescent light irradiation increased the bacteria repair.The increase of UV dosage could cause more...
Photolysis of chlortetracycline in aqueous solution: Kinetics, toxicity and products

Yong Chen,Hua Li,Zongping Wang,Tao Tao,Dongbin Wei,Chun Hu,

环境科学学报(英文版) , 2012,
Revisiting Characteristics of Ionic Liquids: A Review for Further Application Development  [PDF]
Rusen Feng, Dongbin Zhao, Yongjun Guo
Journal of Environmental Protection (JEP) , 2010, DOI: 10.4236/jep.2010.12012
Abstract: In literature concerning ionic liquid (IL) applications, the commonly accepted properties of ionic liquids are frequently mentioned. For example, ionic liquids are described as possessing immeasurably low vapor pressure, being “green material”, non-coordinating, physically and chemically stable, and non-toxic, to name a few. However, all these descriptions are deemed “not exact” [1] as intensive research on ionic liquid properties continues. This review highlights the most recent developments in IL chemistry where the “well-known” description of IL properties sometimes proves to be inaccurate. However, in the authors’ opinion, all these new research developments concerning ionic liquid properties serve to update knowledge on the typical physical and chemical properties of ILs, which is significant to both theoretical research and industrial applications. This review presents an opportunity to understand IL through a more complete and accurate view. It seeks to pave the way for further studies on IL application in various fields.
Equation-free, multiscale computation for unsteady random diffusion
Dongbin Xiu,Ioannis Kevrekidis
Mathematics , 2005,
Abstract: We present an ``equation-free'' multiscale approach to the simulation of unsteady diffusion in a random medium. The diffusivity of the medium is modeled as a random field with short correlation length, and the governing equations are cast in the form of stochastic differential equations. A detailed fine-scale computation of such a problem requires discretization and solution of a large system of equations, and can be prohibitively time-consuming. To circumvent this difficulty, we propose an equation-free approach, where the fine-scale computation is conducted only for a (small) fraction of the overall time. The evolution of a set of appropriately defined coarse-grained variables (observables) is evaluated during the fine-scale computation, and ``projective integration'' is used to accelerate the integration. The choice of these coarse variables is an important part of the approach: they are the coefficients of pointwise polynomial expansions of the random solutions. Such a choice of coarse variables allows us to reconstruct representative ensembles of fine-scale solutions with "correct" correlation structures, which is a key to algorithm efficiency. Numerical examples demonstrating accuracy and efficiency of the approach are presented.
Ecological Risk Assessment Methodology of Toxic Pollutants in Surface Water and Sediments: A Review

Zhao Jianliang,Ying Guangguo,Wei Dongbin,Ren Mingzhong,

生态毒理学报 , 2011,
Abstract: Numerous toxic pollutants enter into water and sediments due to human activities, thus causing adverse effects on aquatic organisms. Hence, conducting ecological risk assessment of contaminants and screening high-risk contaminants are the basis of risk management of contaminants and ecosystem protection. In this paper, we reviewed the methodologies of ecological risk assessment for toxic pollutants in aquatic environment used in the United States, European Union and other developed countries. Basic methodology of risk assessment for contaminants in surface water and sediments includes the following three processes: (a) Exposure assessment, which is carried out using predicted or measured environmental concentrations (PECs or MECs); (b) Impact assessment, which is performed using predicted no effect concentrations (PNECs) derived from aquatic toxicity data through dose-effect relationship; (c) Risk characterization, which is ranked by risk quotient (RQ) from the ratio of PEC (or MEC) to PNEC. However, for the pollutants lacking toxicity data in sediments, the risk assessment of the organic pollutants can be carried out using the aquatic risk assessment method after obtaining the concentration of the pollutants in pore water, which is calculated from the concentration in sediments according to the organic carbon-normalized sediment/water partition coefficient of the organic pollutant. And for the metal pollutants in sediments, the risk assessments can be characterized by risk assessment code (RAC) or by the subtraction method of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM). Based on the review, we proposed a risk assessment methodology for toxic pollutants in surface water and sediments in China, aiming to provide information for contamination risk management of China.
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