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Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

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Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong Department of Applied Physics, hunan university, changsha 410082. china College of Materials Science and {2., hunan university, changsha 410082. china College of chemistry and chemical {2., hunan university, changsha 410082. china 1. Department of Applied Physics Human University 410082 Changsha China 2. College of Materials Science and engineering Hunan University 410082 Changsha China 3. College of chemistry and chemical {2. Hunan University 410082 Changsha China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12.0 12.0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

Size distributions and magic number characteristics of cluster configurations formed during solidification processes of liquid metal Al

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Science china(Technological Sciences) 2006年第2期49卷 172-187页

作者： LIU Rangsu1, LIU Fengxiang1, DONG Kejun1, ZHENG Caixing1, LIU Hairong2. PENG Ping2.& LI Jiyong3 1. Department of Physics, hunan university, changsha 410082. china 2. Department of Material Science and {2., hunan university, changsha 410082. china 3. Department of chemistry, hunan university, changsha 410082. china 1. Department of Physics Hunan University Changsha 410082 China 2. Department of Material Science and engineering Hunan University Changsha 410082 China 3. Department of chemistry Hunan University Changsha 410082 China

A molecular dynamics simulation study has been performed for a large systemconsisting of 100000 liquid metal Al atoms to investigate the formation and magic numbercharacteristics of the cluster configurations formed during the rapid solidification processes. Thecluster-type index method (CTIM) has been adopted to describe various types of clusterconfigurations. The results indicate that the icosahedral clusters (12.0 12.0) and theircombinations play the most important role in the rnicrostructure transitions during solidificationprocesses; for the cluster configurations of different levels formed by various combinations withdiffering numbers of basic clusters, their size distributions possess obvious magic number sequencewhich is in turn as 13(13), 19(2.), 2.-2.(2.), 32.33(32., 39-40, 43-44, 48..., (those in bracket arethe corresponding value in liquid state); the magic numbers correspond to the peak value positionsof the cluster numbers for corresponding level formed with various combinations by 1, 2. 3, 4, 5, 6,7, ...basic clusters, respectively. This magic number sequence is in good agreement with theexperimental results obtained by Harris et al. At the same time, this simulation study also gives ascientific and reasonable explanation to these experimental results.

关键词： liquid metal, solidification processes, cluster configuration, magic numbers, computer simulation.

Piezoelectric transmission spectroelectrochemistry with a normal piezoelectric quartz crystal as an optically-transparent electrode

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Chinese Journal of chemistry 1994年第5期12卷 425-431页

作者： XIE, Qing-Ji PANG, Xiao-Yong NIE, Li-Hua YAO, Shou-Zhuo Department of chemistry and chemical {2., hunan university, changsha, hunan 410082. china Department of chemistry and chemical {2. Hunan University Changsha Hunan 410082 China

Piezoelectric transmission spectroelectrochemistry (PTSEC), i.e., the combination of electrochemistry and spectroelectrochemistry (SEC) with electrochemical quartz crystal microbalance (EQCM) technique is reported by using a normal piezoelectric quartz crystal (PQC) as an optically-transparent electrode (OTE). A theoretical relationship between the PQC response and the spectroelectrochemical response is derived and used to estimate the apparent molar absorptivity of the absorbing species deposited on the OTE on the PQC surface. The complex of copper with aspartic acid is used to test this new PQC-SEC technique. Results show that the combination of three such diverse techniques provides a very useful methodology for studying electrode processes and electrode surface characteristics in situ.

关键词： Piezoelectronic transimission spectroelectrochemistry optically-transparent electrode electrochemical quartz crystal microbalance copper aspartic acid.

Study on H atoms diffusion and adsorption properties of MgH_2.V systems

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Science china(Technological Sciences) 2008年第7期51卷 979-988页

作者： ZHOU DianWu1,2. LIU JinShui3 & PENG Ping3 1 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, hunan university, changsha 410082. china 2.College of Mechanical and Automatic {2., hunan university, changsha 410082. china 3 College of Materials Science and {2., hunan university, changsha 410082. china 1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha 410082 China 2. College of Mechanical and Automatic engineering Hunan University Changsha 410082 China 3. College of Materials Science and engineering Hunan University Changsha 410082 China

Based on experimental results that VH0.81/MgH2.interface was found during the process of mechanically milling MgH2.5at.%V nanocomposite, H atoms diffusion and adsorption properties of MgH2.V systems have been investigated by using a first-principles plane-wave pseudopotential method based on the density functional theory. The results are as follows. When VH/MgH2.interface is formed due to V alloying MgH2.phase, the vacancy formed by H atoms near VH phase region is more stable than that without V alloying, while vacancy near MgH2.phase region is less stable than that without V alloying. During the process of H atoms diffusion after V alloying, the max migration barrier energy of H atoms in MgH2.V systems is reduced compared with that of MgH2.phase, which means that H atoms diffuse easily. When H diffuses into VH from MgH2.across VH/MgH2.interface, among three substitutions such as the replacement of H for V vacancy, or interstitial site or V atoms, the replacement of H for V vacancy has the strongest diffusion ability, next interstitial site, and finally V atoms site. As far as H adsorbed on different surfaces of VH phase is concerned, physical adsorption is carried out more easily than chemical adsorption, and the behavior of H atoms adsorbed on the surface near VH phase region can be found more easily than that near MgH2.phase region.

关键词： plane-wave pseudopotential theory magnesium hydride diffusion adsorption

A Series Piezoelectric Quartz Crystal Response Kinetics for *** Growth in the Presence of Cu(Ⅱ)

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Journal of Central South university 2000年第1期12卷 15-19页

作者： CHAI Li yuan 1,2.,WEI Wan zhi 2.YAO Shou zhuo 2.1. Department of Metallurgical Science and engineering, Central South university of Technology, {2. 410083, china 2. College of chemistry and chemical engineering, hunan university, {2. 1. Department of Metallurgical Science and engineering Central South University of Technology 410083 Changsha China 2. College of chemistry and chemical {2. Hunan University 410082 Changsha China

The kinetics on the growth of *** in the presence of Cu(Ⅱ) was studied using of series piezoelectric quartz crystal (SPQC). Arsenic ion inhibits the growth of *** , which is consistent with the previous results by other measuring methods. This further demonstrates that the SPQC can monitor the chemical activity of *** growth. Cupric ion accelerates the growth of *** . The mechanism was discussed, i. e., copper promotes the protein enzyme of *** , rusticyanin, to form over the range of cupric ion concentration studied. The reaction order of cupric ion in accelerating the bacterial growth is 0.067. The growth of *** is dependent on temperature, the apparent reaction activation energy decreases from 2..56 kJ/mol to 18.32.kJ/mol because of the addition of 10 mg/L Cu(Ⅱ) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

关键词： series piezoelectric quartz crystal T.ferrooxidans growth kinetics sigmoid curve cupric ion

Inductance-based sensing technique for wireless,remote-query measurement in liquid media

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Science china chemistry 2010年第6期53卷 1391-1397,1460页

作者： MA Lin,NIE Zhou,HUANG Yan & YAO ShouZhou State Key Laboratory of Chemo/Biosensing and Chemometrics,College of chemistry and chemical {2.,hunan university,changsha 410082.china 1. State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical Engineering Hunan University Changsha 410082 China

A novel inductance-based sensing technique is presented for remote query measurement in different liquid media including organic solvents and inorganic *** inorganic solutions tested included salt solutions of different concentrations,and the organic solvents detected included 1,4-dioxane and *** extend the application of the sensor,bacterial culture media were also detected,and the growth of Escherichia coli (***) was *** influential factors which may affect the inductance responses were studied in *** was found that quantitative relationships exist between the sensor’s inductance response and the physico-chemical parameters of the liquid *** sensor’s inductance response (L) decreases with the increase of salt concentration (C) and its ionic valence (e) according to a semi-logarithmic equation LgL =-aeC + b,where a and b are constants,which is in accordance with the theoretically deduced *** inductance variation rate (ΔK) increases directly with the temperature (T): ΔK = a′ T + b′.As for organic solutions,the sensor’s inductance was found to increase with the increasing permittivity of the organic *** wireless sensor we designed is simple and easy to *** has the potential for remote determination of not only chemical substances but also microbiological species such as *** the newly developed inductance-based sensor,the pathogenic *** was monitored with a limit of detection of 10 cells/mL and a linear semi-logarithmic range of 1.0 × 101 to 2.5 × 109 cells/mL.

关键词： inductance sensor remote-query liquid medium wireless bacterial detection E. coli.

Cell-SELEX-based aptamer-conjugated nanomaterials for enhanced targeting of cancer cells

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Science china chemistry 2011年第8期54卷 1218-1226页

作者： KONG RongMei, CHEN Zhuo, YE Mao, ZHANG XiaoBing & TAN WeiHong State Key Laboratory for Chemo/Biosensing and Chemometrics College of chemistry and chemical {2., hunan university, changsha 410082. china 1. State Key Laboratory for Chemo/Biosensing and Chemometrics College of chemistry and chemical {2. Hunan University Changsha 410082 China

Early detection and treatment of cancer depends on developing highly sensitive and specific methods for targeting cancer cells. To do this, aptamers, which are generated by a novel technique caUed ceU-SELEX （systematic evolution of ligands by exponential enrichment）, have been widely applied in cancer cell targeting based on such merits as high target affinity and specificity, small size, minimal immunogenicity, and ease of chemical modification. Furthermore, aptamers can gain more flexibility as cancer cell targeting tools when conjugated to nanomaterials, including metallic nanoparticles, quantum dots, silica nanoparticles, and carbon nanomaterials, among others. In this review, we discuss the use of cell-SELEX-based aptamer-nanomaterials conjugates as novel molecular tools for enhanced targeting of cancer cells.

关键词： celI-SELEX aptamer nanomaterial cancer cells targeting

3D-QSAR studies on glycogen phosphorylase inhibitors by flexible comparative molecular field analysis

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Science china chemistry 2007年第4期50卷 568-573页

作者： ZHOU Peng1 & LI ZhiLiang1,2.1 College of chemistry and chemical {2., Chongqing university, Chongqing 400044, china 2.State Key Laboratory of Chemo/Biosensing and Chemometrics, changsha 410082. china 1. College of chemistry and chemical {2. Chongqing University Chongqing 400044 China 2. State Key Laboratory of Chemo/Biosensing and Chemometrics Changsha 410082 China

Canceling grids accommodating probes in comparative molecular field analysis (CoMFA), the idea of flexibleness is introduced into the CoMFA, and in combination with swarm intelligent algorithm which attempts to optimize distributions of diverse probes around drug molecules, a new 3D-QSAR method is proposed in this context as flexible comparative molecular field analysis (FCoMFA). In preliminary at-tempts to performing QSAR studies on 47 glycogen phosphorylase inhibitors, FCoMFA is employed and confirmed to be potent to exploring ligand-receptor interaction manners at active positions and thus to generating stable and predictable models. Simultaneously by an intuitive graphics regarding probe distribution patterns, impacts of different substituted groups on activities is also given an insight into.

关键词： flexible comparative molecular field analysis (FCoMFA) three-dimensional quantitative structure-activity relationship (3D-QSAR) particle swarm optimization algorithm (PSO) glycogen phosphorylase inhibitor probe distribution pattern

Boron rings containing planar octa- and enneacoordinate cobalt, iron and nickel metal elements

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Science china chemistry 2008年第7期51卷 607-613页

作者： LUO Qiong School of chemistry and chemical {2., Central South university, changsha 410083, china School of chemistry and chemical {2. Central South UniversityChangsha 410083China

For a series of boron rings with planar hyper-coordinate 8th group transition metal atoms, singlet 1FeB8-2. multiplet kFeB9n (n = -1, k = 1; n = 0, k = 2., singlet 1CoB8n(n = -1, +1, +3), multiplet kCoB9n (n = +1, k = 2. n = 0, k = 1) and singlet 1NiB9+, the geometry structures have been optimized to be local minima on corresponding potential hyper-surfaces. The electron structures are discussed by orbital analysis and the aromaticity is predicted by nucleus-independent chemical shifts calculation at both the B3LYP/6-311+G* and BP86/6-311+G* levels of theory, respectively. The results suggest that all these structures with high symmetry planar geometries are stable and have aromatic properties with six π valence electrons.

关键词： planar hyper-coordinate transition metal DFT