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A simple solution route to control synthesis of Fe_3O_4 nanomaterials at low temperature and their magnetic properties

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science china Chemistry 2009年第7期52卷 916-923页

作者： LIU Yi1,2. CHEN Yun1, ZENG YuPing2.& WANG ShiLong3 1 Department of Chemistry and Chemical Engineering, Zaozhuang University, Zaozhuang 2.7160, china 2.shanghai Institute of Ceramics, Chinese Academy of {2.s, shanghai 2.0050, china 3 school of life science and technology, tongji University, shanghai 2.0092. china 1. Department of Chemistry and Chemical Engineering Zaozhuang University Zaozhuang 277160 China 2. shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China 3. school of life {2. and technology Tongji University Shanghai 200092 China

A series of nanostructured iron compounds including cubic Fe3O4 and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60-100℃) solution method. In the whole process, the interaction between FeCl2.4H2. and methenamine (C6H12.4) was carried out through a reflux device under different reaction conditions such as temperature, solvent, and duration. The samples were detected by XRD, TEM, SAED, physical property measurement system, and Mssbauer spectroscopy, separately. The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies, and cubic Fe3O4 took on grain nanostructure. Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite. Mssbauer spectroscopy testified the sample consisting of cubic magnetite rather than γ-Fe2.3. In addition, a possible growth mechanism of cubic magnetic nanoparticles under different conditions was discussed.

关键词： magnetic nanoparticles cubic Fe3O4 oxidation-coprecipitation method reflux magnetic properties at room temperature Mssbauer spectrum

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3 and Guo Shengli3(1. College of life sciences, Zhejiang University, Hangzhou 310058, {2. 2. Imaging Department of tongji Hospital of tongji University, shanghai 2.0065, {2. 3. College of Mathematics and Physics, Nanjing University of Information science and technology, Nanjing 2.0044, {2.) College of life sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China College of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

The protection effect of β-CD on DNA damage induced by ultrafine TiO_2

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science china Chemistry 2007年第2期50卷 272-275页

作者： ZHU RongRong,WANG ShiLong,SUN XiaoYu,ZHANG Rui & YAO SiDe school of life {2. and technology,tongji University,shanghai 2.0092.china 1. school of life {2. and technology Tongji University Shanghai 200092 China

Under the photocatalysis of 365 nm ultraviolet radiation,ultrafine TiO2.caused the oxidative damage of Teasy plasmid DNA. The damage was determined by gel-electrophoresis. Then,a different dose of β-CD was added to the reaction,and the damage was restrained. The rate of damage restraining reached 97% when the mass of β-CD was 4 times as that of TiO2. Through UV scan and IR spectroscopy,it was found that the Ti-O of ultrafine TiO2.was bound with -OH of β-CD cavum and the -OH on the surface of ultrafine TiO2.disappeared,so the formation of ?OH was controlled. The ultrafine TiO2.has been widely used,but it was determined to be carcinogenic by some research. The protection effect of β-CD to DNA in the molecular level takes a new look on the surface modification of nano particles to decrease the toxic effect.

关键词： β-CD ultrafine TiO2 plasmid DNA oxide damage bond reaction damage restrain

Impact and mechanism of TiO_2.nanoparticles on DNA synthesis in vitro

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science china Chemistry 2008年第4期51卷 367-372页

作者： LI ShiQiang, ZHU Hong, ZHU RongRong, SUN XiaoYu, YAO SiDe & WANG ShiLong school of life {2. and technology, tongji University, shanghai 2.0092. china 1. school of life {2. and technology Tongji University Shanghai 200092 China

The impact of TiO2.nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO2.nanoparticles on DNA synthesis was investigated by adding TiO2.nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO2.nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction be- tween TiO2.nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO2.nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi- croscale TiO2.particles at the equivalent concentration and the inhibition effect of TiO2.nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO2.nanoparticles interact with the DNA polymerase through physical adsorption while TiO2.nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO2.nanoparticles are in the following order: the primer > the tem- plate > the DNA polymerase.

关键词： TiO2 nanoparticles PCR DNA synthesis molecular mechanism

Phase transition in the Zr_(60)Al_(15)Ni_(2.) bulk metallic glass subjected to rolling at room temperature

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science china(Technological sciences) 2006年第6期49卷 655-662页

作者： YAN Zhijie1, 2. LI Jinfu1, ZHOU Yaohe1 & WU Yanqing3 1. State Key Laboratory of Metal Matrix Composites, school of Materials science and Engineering, {2. Jiao Tong University, {2. 2.0030, china 2. school of Materials science and Engineering, Taiyuan University of science and technology, Taiyuan 03002., china 3. school of Environmental science and Engineering, {2. Jiao Tong University, {2. 2.0030, china State Key Laboratory of Metal Matrix Composites School of Materials Science Engineering Shanghai Jiao Tong University Shanghai 200030 China school of Materials science Engineering Taiyuan University of Science technology Taiyuan 030024 China school of Environmental science Engineering Shanghai Jiao Tong University Shanghai 200030 China

The microstructure evolution of the Zr60Al15Ni2. metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC); high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns; exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees . As is not large than 2.%, the values of FWHM; ΔH are lower than that of the as-cast state. When reaches 30%, the values of FWHM; ΔH become larger than that of the as-cast state, while their values begin to decrease again as reaches about 85%. These results indicate that the reversible transitions between ordered; disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering; shear-induced disordering during rolling.

关键词： metallic glasses, plastic deformation, phase transformations, shear bands.

cDNA cloning,sequence analysis,and recombinant expression of akitonin beta,a C-type lectin-like protein from Agkistrodon acutus

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Acta Pharmacologica Sinica 2004年第03期25卷 118-123页

作者： Xiang-dong ZHA1,2.Jing LIU1,Kang-sen XU3 1 school of life {2.,University of {2. and technology,Hefei 2.002. school of life {2.,Anhui University,2.Hefei 2.0039 National Institute for Control of Pharmaceuticals and Biological Products,Beijing 100050,china 3 school of life {2. University of Science and Technology school of life {2. Anhui University National Institute for Control of Pharmaceuticals and Biological Products Beijing 100050 China

AIM: To clone the cDNA of a new member of snake venom C-type lectin-like proteins, to study its structure- function relationships and to achieve its recombinant production. METHODS: PCR primers were designed based on the homology and cDNA was amplified by RT-PCR using total RNA from snake venom gland as the template. The PCR products were cloned into the plasmid pGEM-T and sequenced. The deduced protein sequence was analyzed with some bioinformatic programs. A recombinant expression plasmid was constructed using pBAD- TOPO as vector and transformed into *** TOP10 competent cells. RESULTS: A novel cDNA sequence encod- ing akitonin β was found and accepted by GenBank (accession number AF387100). Akitonin β consists of a typical carbohydrate recognition domain (CRD) of C-type lectins, and it is homologous with other snake venom C-type lectin-like proteins. It was predicted to be a platelet antagonist. Upon induction with arabinose rAkitonin β express- ing in E coli was achieved at a high level (superior to 150 mg/L). The recombinant fusion protein exhibited inhibitory activities on rat platelet aggregation in vitro. CONCLUSION: A new member of snake venom C-type lectin-like proteins was discovered and characterized, and an efficient recombinant expression system was estab- lished for its production.

关键词： snake venoms cDNA akitonin C-type lectin-like proteins recombinant proteins structure- activity relationship

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2.1. Department of Civil Engineering,shanghai University,shanghai 2.0072.{2. 2. school of Transportation Engineering,tongji University,shanghai 2.0092.{2. 1. Department of Civil Engineering Shanghai University Shanghai 200072 China 2. school of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

CO observations of massive star forming regions at different evolutionary phases

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science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 626-640页

作者： CHEN Xi1,2. XU Ye1,3, SHEN Zhiqiang1,3 & LI Jingjing1,2.1. shanghai Astronomical Observatory, Chinese Academy of sciences, shanghai 2.0030, china 2. Graduate school of the Chinese Academy of sciences, Beijing 100034, china 3. Joint Institute for Galaxy and Cosmology, shanghai Astronomical Observatory and the University of science and technology of china, shanghai 2.0030, china shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate school of the Chinese Academy of sciences Beijing 100034 China Joint Institute for Galaxy Cosmology Shanghai Astronomical Observatory the University of science technology of china Shanghai 200030 China

The 12.O (J=1-0), 13CO (J=1-0) and C18O (J=1-0) emissions in 9 massive star forming regions, which are believed to be at different stages of massive star formation, were mapped with the 13.7 m millimeter wave telescope at Qinghai Station of Purple Mountain Observatory. Of the observed 9 sources, 13CO cores were detected in seven of them, and C18O cores in five of them. And only two sources associated with C18O cores and H2. masers showed the extended structures and strong outflows. This is the first detection of outflow associated with IRAS 2.566+582. in the observing field of S152.S153. The physical parameters of cores and outflows for these sources, derived from Local Thermal Equilibrium (LTE) analysis, are presented. These observing results suggest that the C18O cores will only appear when the gas density is high enough and the probability to have an outflow is very high when the clumps show the C18O and H2. maser simulta- neously.

关键词： star formation cloud core outflow H2. maser

Bayesian cognitive trust model based self-clustering algorithm for MANETs

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science china(Information sciences) 2010年第3期53卷 494-505页

作者： WANG Wei1,2.3 & ZENG GuoSun1,2.31Department of Computer science & technology, {2. University, shanghai 2.0092. china 2.2. Branch, National Engineering & technology Center of High Performance Computer, shanghai 2.0092. china 3Key Loboratory of Embedded System and Service Computing, Ministry of Education, shanghai 2.0092. china 1. Department of Computer science & technology Tongji University Shanghai 200092 China2. Tongji Branch National Engineering & Technology Center of High Performance Computer Shanghai 200092 China3. Key Loboratory of Embedded System and Service Computing Ministry of Education Shanghai 200092 China

With the introduction of mobile Ad hoc networks (MANETs), nodes are able to participate in a dynamic network which lacks an underlying infrastructure. Before two nodes agree to interact, they must trust that each will satisfy the security and privacy requirements of the other. In this paper, using the cognition inspired method from the brain informatics (BI), we present a novel approach to improving the search efficiency and scalability of MANETs by clustering nodes based on cognitive trust mechanism. The trust relationship is formed by evaluating the level of trust using Bayesian statistic analysis, and clusters can be formed and maintained autonomously by nodes with only partial knowledge. Simulation experiments show that each node can form and join proper clusters, which improve the interaction performance of the entire network. The essence of the underlying reason is analyzed through the theory of complex networks, revealing great scalability of this method.

关键词： trust model MANET self-clustering Bayesian method cognitive mobile