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AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

Science China Chemistry 2006年第3期49卷 256-266页

作者： GE Xiaopeng1, ZHOU Yanmei2. Lü Chunhua1 & TANG Hongxiao1 1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, beijing 100085, China 2. School of Civil Engineering & Architecture, beijing Jiaotong {2., beijing 100044, China 1. State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. School of Civil Engineering & Architecture Beijing Jiaotong University Beijing 100044 China

Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 2.0 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.

关键词： atomic force microscopy (AFM) dissolved humic substances morphology aggregation adsorption

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Polycistronic strategy for cyanobacterial expression vector construction: Co-transcription of a human gene and a selective marker gene

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Progress in Natural Science:Materials International 2005年第9期15卷 798-803页

作者： ZHANG Yukun1, SHI Dingji2. ZHAO Feifei1, YU Meimin1 and RU Binggen1(1. college of Life Science, Peking university, {2. 100871, China 2. college of Marine Sciences & Engineering, Tianjin university of Science & Technology, Tianjin 300450, China) college of Life Science Peking University Beijing 100871 China. college of Marine Sciences & Engineering Tianjin University of Science & Technology Tianjin 300450 China

A polycistronic expression vector, pKGA-NTF1, was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002.chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3 gene (NTF1) to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1 gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.

关键词： cyanobacterial transformation human Trefoil factor 3 polycistronic expression Synechococcus sp. PCC 7002 vector construction.

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Complex variable method for plane elasticity of icosahedral quasicrystals and elliptic notch problem

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 773-780页

作者： LI LianHe1,2.& FAN TianYou1 1 Department of Physics, beijing Institute of Technology, beijing 100081, China {2. of Mathematics Science, Inner Mongolia Normal university, Hohhot 01002., China Department of Physics Beijing Institute of Technology Beijing 100081 China college of Mathematics Science Inner Mongolia Normal University Hohhot 010022 China

The complex variable method for the plane elasticity theory of icosahedral quasicrystals is developed. Based on the general solution obtained previously, complex representations of stress and displacement components of phonon and phason fields in the quasicrystals are given. With the help of conformal transformation, an analytic solution for the elliptic notch problem of the material is presented. The solution of the Griffith crack problem can be observed as a special case of the results. The stress intensity factor and energy release rate of the crack are also obtained.

关键词： icosahedral quasicrystals plane elasticity elliptic notch complex variable method

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Empirical likelihood-based inference in a partially linear model for longitudinal data

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Science China Mathematics 2008年第1期51卷 115-130页

作者： XUE LiuGen~(1+) & ZHU LiXing~2.1 college of Applied Sciences, beijing {2. of Technology, beijing 10002., China 2.Department of Mathematics, Hong Kong Baptist {2., Hong Kong, China college of Applied Sciences Beijing University of Technology Beijing 100022 China Department of Mathematics Hong Kong Baptist University Hong Kong China

A partially linear model with longitudinal data is considered, empirical likelihood to infer- ence for the regression coefficients and the baseline function is investigated, the empirical log-likelihood ratios is proven to be asymptotically chi-squared, and the corresponding confidence regions for the pa- rameters of interest are then constructed. Also by the empirical likelihood ratio functions, we can obtain the maximum empirical likelihood estimates of the regression coefficients and the baseline function, and prove the asymptotic normality. The numerical results are conducted to compare the performance of the empirical likelihood and the normal approximation-based method, and a real example is analysed.

关键词： partially linear model empirical likelihood confidence region longitudinal data 62.05 62.15 62.2.

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Effects of scandium addition on microstructure and mechanical properties of ZK60 alloy

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Progress in Natural Science:Materials International 2011年第1期21卷 59-65页

作者： Fu-sheng PAN~(1,2.,Ting-ting LIU~(1,2.,Xi-yan ZHANG~(1,2.,Ai-tao TANG~(1,2.,Wei-qing WANG~(1,2. 1.National Engineering Research Center for Magnesium Alloys,Chongqing university,Chongqing 400045,China 2.college of Materials Science and Engineering,Chongqing university,Chongqing 400045,China [a] National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing 400045 China [b] college of Materials Science and Engineering Chongqing University Chongqing 400045 China

The effects of Sc addition on the microstructure and mechanical properties of the ZK60 wrought magnesium alloy were investigated by using optical microscope,scanning electron microscopy,X-ray diffraction and tensile *** experimental results show that a minor Sc addition to ZK60 alloy has an obvious effect on the refinement of the microstructure of the ZK60 alloy. During hot extrusion,incomplete dynamic recrystallization occurs in all the alloys,and the recrystallized grains become much finer with increasing Sc *** tensile strengths of ZK60 evidently increase with the addition of Sc,but the elongations decrease. The ZK60 alloy with 0.6%(mass fraction) Sc addition is found to have the tensile strength of about 350 MPa and the yield strength of about 2.0 *** T6 heat treatment,the tensile strength of the alloy containing 0.6%Sc remains almost ***, the yield strength of the alloy increases up to 352.MPa,and the ratio of the tensile strength to the yield strength is close to 1.

关键词： wrought magnesium alloy scandium microstructure mechanical properties

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Generalized quantum state sharing of the arbitrary two particles state

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Science China(Physics,Mechanics & Astronomy) 2010年第11期53卷 2064-2068页

作者： WANG Chuan 1,2.ZHANG Yong 1,2.& JIN GuangSheng 1,2.1 School of Science,beijing university of Posts and Telecommunications,beijing 100876,China 2.Key Laboratory of Optical Communication and Lightwave Technologies,beijing university of Posts and Telecommunications,beijing 100876,China 1. School of Science Beijing University of Posts and Telecommunications Beijing 100876 China2. Key Laboratory of Optical Communication and Lightwave Technologies Beijing University of Posts and Telecommunications Beijing 100876 China

This paper has proposed a generalized quantum state sharing protocol of an arbitrary two-particle state using non-maximally GHZ states and generalized Bell state *** sender Alice performs two-particle generalized Bell state measurements on her two particles in the state sharing process and the controller takes measurements on his particles and transfers the quantum information to the receiver with entanglement swapping by the cooperation of the other *** is found that the use of nonmaximally entangled state in quantum state sharing has enabled the secure sharing of the quantum state.

关键词： quantum state sharing quantum entanglement arbitrary two particles state

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Singularity Detecting with the SecondGeneration Wavelet

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Wuhan university Journal of Natural Sciences 2004年第6期9卷 871-874页

作者： XU Bing-lian 1,2., YI Xu-ming 1 1.School of Mathematics and Statistics, Wuhan university, Wuhan 430072. Hubei, China 2.college of Science,Nanjing Agriculture university,Nanjing 2.0095,Jingsu,China School of Mathematics and Statistics Wuhan University Wuhan 430072 Hubei China

Adopting the lifting scheme, introduced by Sweldens, a new wavelet is constructed. It overcomes the shortcoming of the classical wavelets that has no flexibility in the number of vanishing moment. Two examples are given to prove the second-generation wavelets's potentialities in the singularity detection of signal: a wavelet with vanishing moment and symmetry can be constructed according to the problem. Key words biorthogonal wavelet - lifting scheme - secondgeneration wavelets - singularity CLC number O 174.2.Foundation item: Supported by the National Natural Science Foundation of China (19602.14)Biography: XU Bing-lian (1977-), female, Master candidate, research direction: the wavelets application.

关键词： biorthogonal wavelet lifting scheme secondgeneration wavelets singularity

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Microstructure and Frictional Behavior of Fe-based Amorphous Metallic Coatings Prepared by Atmospheric Plasma Spraying

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稀有金属材料与工程 2011年第S3期40卷 160-165页

作者： Zhou Zheng1,2. Wang Lu2. He Dingyong1, Liu Yanbo2. Zhang Guanzhen1 1 beijing university of Technology, beijing 10012., China 2.beijing Institute of Technology, beijing 100081, China beijing Univ Technol Beijing 100124 Peoples R China beijing Inst Technol Beijing 100081 Peoples R China

Amorphous metallic coatings with a composition of Fe48Cr15Mo14C15B6Y2.were prepared by means of atmospheric plasma spraying (APS) process under different conditions. The microstructure and frictional behavior were characterized simultaneously in this article. The results show that the as-deposited coatings consist of amorphous matrix and some precipitated nanocrystals, while the amorphous fraction and particle deformation as well as crystallization mechanism are significantly sensitive to the spraying parameters. The amorphous coatings express high microhardness and excellent wear resistance under dry frictional wear condition, which attributes to the inherent characteristic of amorphous phase and the dispersion strengthening of precipitated nanocrystals. The dominant wear mechanism of the amorphous coatings is fatigue wear accompanying with oxidative wear. In addition, the microhardness and wear resistance of the amorphous coatings were improved by optimizing spraying parameters, owing to the effect of both structural character and proper proportional of amorphous and nanocrystals fraction.

关键词： Fe-based amorphous coating APS microstructure friction

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Corrosion of Different Materials in Combustion Chamber of Yellow Phosphorus Tail Gas in Industrial Boiler

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Journal of Wuhan university of Technology(Materials Science) 2010年第1期25卷 53-57页

作者：郜华萍宁平 college of Environmental Science & Engineering Kunming University of Science and Technology

The corrosion of materials in combustion chamber of yellow phosphor tall gas was investrgated. The results reveal that the corrosion behavior is different for different materials under actual work conditions.

关键词： yellow phosphorus tail gas corrosion industrial boiler carbon metal material

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Study on Ultra-sonic Frequency Pulse TIG of Titanium Alloy

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稀有金属材料与工程 2011年第S3期40卷 259-262页

作者： Zhou Shuiliang1, Zhao Haitao1, Qi Bojin 2.1 beijing Aeronautical Manufacturing Technology Research Institute, Aeronautical Key Laboratory for Aviation Joining Technology, beijing 10002., China 2.0} university of Aeronautics & Astronautics, beijing 100191, China beijing Aeronaut Mfg Technol Res Inst Aeronaut Key Lab Aviat Joining Technol Beijing 100024 Peoples R China beijing Univ Aeronaut & Astronaut Beijing 100191 Peoples R China

Ti-6Al-4V alloy is used extensively in aerospace and aircraft because of its excellent comprehensive properties and outstanding machinability. Ti-6Al-4V alloy was welded by conventional tungsten iner-gas arc welding (TIG) and ultra-sonic frequency pulse TIG welding (U-TIG) respectively. The welding quality was tested by X-ray, and the mechanical properties of welded joint were tested , the microstructure and the fracture appearance of welded joint were observed by means of optical microscope and SEM .The results show that the joints were welded successfully by U-TIG welding, U-TIG welding could reduced pores defects of welded joint. With the increment of ultra-sonic pulse frequency, the microstructure became more and more fine and was inclined to equiaxed crystal. Moreover, the properties of joint by U-TIG welding were improved compared with that of conventional TIG. Tensile fractures of joints by TIG welding and U-TIG welding all presented character of quasi-cleavage crack, but the cellular dendrite depredation was not observed obviously in U-TIG joint.

关键词： ultra-sonic frequency pulse TIG welding tungsten iner-gas arc welding titanium alloy

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