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Now showing items 65 - 80 of 189

  • Band alignment in molecular devices: Influence of anchoring group and metal work function

    Wang, Jian-guo   Prodan, Emil   Car, Roberto   Selloni, Annabella  

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  • DFT Study of Structural and Electronic Properties of PdO/HZSM-5

    Wang, Jian-guo   Liu, Chang-jun   Fang, Zhiping   Liu, Yue   Han, Zhongqi  

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  • The point-defect of carbon nanotubes anchoring Au nanoparticles RID G-2026-2011 RID B-3341-2010

    Lv, Yong-An   Cui, Yan-Hong   Li, Xiao-Nian   Song, Xiang-Zhi   Wang, Jian-Guo   Dong, Mingdong  

    The understanding of the interaction between Au and carbon nanotubes (CNTs) is very important since Au/CNTs composites have wide applications in many fields. In this study, we investigated the dispersion of Au nanoparticles on the CNTs by transmission electron microscopy and the bonding mechanism between Au clusters and CNTs by means of density functional theory calculations. Both experimental and theoretical studies show that point defects are the anchoring sites of Au nanoparticles. The mechanisms of enhanced bond between Au and CNTs via the point defects are explained by the analysis of density of states, charge transfer and frontier molecular orbitals. (C) 2010 Elsevier B.V. All rights reserved.
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  • Modulation of bonding between noble metal monomers and CNTs by B-, N-doping RID G-2026-2011

    Lv, Yong-An   Cui, Yan-Hong   Xiang, Yi-Zhi   Wang, Jian-Guo   Li, Xiao-Nian  

    By means of density functional theory calculations, we demonstrate that the bonding between noble metal monomers and CNTs can be modulated by the B-, N-doping. But the modulation mechanisms are strongly dependent on the doping element and metal. B-doping significantly enhances the adhesion of Au, Ag on CNTs mainly via the formation the metal-B ionic bond. While N-doping enhance the adhesion of Au, Ag and Pt monomer on CNTs due to the formation of stronger metal carbon covalent bond than that on pristine CNTs, which is caused by electron rich N-CNTs. (C) 2010 Elsevier B.V. All rights reserved.
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  • Effect of Catalyst Preparation on Carbon Nanotube Growth

    Wang, Jian-Guo   Liu, Chang-Jun   Zhang, Yue-Ping   Zhu, Xin-Li   Yu, Kai-Lu   Zou, Jijun  

    A highly dispersed Ni-Fe/Al(2)O(3) catalyst was prepared by glow discharge plasma treatment followed by thermal calcinations. With this plasma prepared catalyst, carbon nanotubes encapsulated with metal particle or filled with nickel nano-wire were produced. This is very different from the conventional catalyst, with which the normal multi-wall carbon nanotubes or nano-capsule chains were synthesized. The plasma preparation leads to a significant change in the interaction between metal and the support.
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  • The effects of swainsonine on the activity and expression of alpha-mannosidase in BRL-3A cells.

    Lu, Hao   Ma, Feng   Wang, Huan   Geng, Peng-Shuai   Wang, Shan-Shan   Wang, Jian-Guo   Wu, Chen-Chen   Zhao, Bao-Yu  

    Swainsonine (SW) is the principal toxic ingredient of locoweeds, which can cause intensive vacuolar degeneration because of alpha-mannosidase inhibition after animal ingestion. While SW can lead to obvious liver damage invivo, the mechanism of hepatotoxic damage caused by SW is not clear. Therefore, BRL-3A cells were treated for 24, 48, and 72h with SW at various concentrations (0, 700, 900, 1100mug/mL). The alpha-mannosidase (AMAN) activity was determined in BRL-3A cells using an enzyme substrate technique. The expression of mRNA and proteins of GM II (MAN2A1) and LAM (MAN2B1) in BRL-3A cells was detected by qPCR and Western-blot. The results showed that SW could significantly reduce the activity of AMAN in a time-dose effect relationship. Compared with the control group, the activity of AMAN significantly decreased only in the group treated with 1100mug/mL SW for 24h (P<0.01), but the activity decreased significantly (P<0.05 or P<0.01) in all experimental groups treated for 48 or 72h. SW also significantly reduced the expression of MAN2A1 and MAN2B1 mRNA and proteins in a time-dose effect relationship (P<0.05 or P<0.01), while the inhibition of SW was stronger for MAN2B1 than for MAN2A1. These results suggest that SW can significantly reduce the activity and expression of alpha-mannosidase thus causing SW-induced hepatotoxic damage. Copyright =C2=A9 2015 Elsevier Ltd. All rights reserved.
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  • A DFT study of synthesis of acetic acid from methane and carbon dioxide

    Wang, Jian-guo   Liu, Chang-jun   Zhang, Yue-ping   Eliasson, Baldur  

    We have previously reported an experimental investigation on synthesis of acetic acid directly from CH4 and CO2 via dielectric-barrier discharge. In this work, a DFT study was conducted using three hybrid DFT methods in order to understand the mechanism of such direct synthesis. It suggests that the synthesis is via two pathways with CO2− and CO as key intermediates. The energy requirement with CO2− pathway is much less than that with CO. The methyl radical formation and the dissociation of CO2 are two limiting steps for the synthesis of acetic acid directly from CH4 and CO2.
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  • Selectivity difference between hydrogenation of acetophenone over CNTs and ACs supported Pd catalysts

    Xiang, Yi-zhi   Lv, Yong-an   Xu, Tie-yong   Li, Xiao-nian   Wang, Jian-guo  

    Selectivity difference between hydrogenation of acetophenone over carbon nanotubes (CNTs) and commercial activated carbons (ACs) supported Pd catalysts has been investigated. The selectivity of alpha-phenylethanol over the Pd/CNTs catalyst is significantly higher than that over the Pd/ACs. The optimal yield of a-phenylethanol over the Pd/CNTs catalyst is 94.2% at 333 K under atmospheric H(2) pressure for 255 mm, but it is only 47.9% over the Pd/ACs catalyst. HRTEM characterization and density functional theory (DFT) study of the two catalysts suggested that the defects of the carbon support are the main anchoring sites for Pd nanoparticles. Additionally, mechanistic study of the acetophenone hydrogenation over the two catalysts suggested that the different adsorption modes of reaction intermediates (products) on the two kinds carbon supported Pd nanoparticles are responsible for the dramatic selectivity difference. (C) 2011 Elsevier B.V. All rights reserved.
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  • SDSS J013127.34-032100.1: A NEWLY DISCOVERED RADIO-LOUD QUASAR AT z=5.18 WITH EXTREMELY HIGH LUMINOSITY

    Yi, Wei-Min   Wang, Feige   Wu, Xue-Bing   Yang, Jinyi   Bai, Jin-Ming   Fan, Xiaohui   Brandt, William N.   Ho, Luis C.   Zuo, Wenwen   Kim, Minjin   Wang, Ran   Yang, Qian   Zhang, Ju-Jia   Wang, Fang   Wang, Jian-Guo   Ai, Yanli   Fan, Yu-Feng   Chang, Liang   Wang, Chuan-Jun   Lun, Bao-Li   Xin, Yu-Xin  

    Very few of the z > 5 quasars discovered to date have been radio-loud, with radio-to-optical flux ratios (radio-loudness parameters) higher than 10. Here we report the discovery of an optically luminous radio-loud quasar, SDSS J013127.34-032100.1 (J0131-0321 in short), at z = 5.18 +/- 0.01 using the Lijiang 2.4 m and Magellan telescopes. J0131-0321 has a spectral energy distribution consistent with that of radio-loud quasars. With an i-band magnitude of 18.47 and a radio flux density of 33 mJy, its radio-loudness parameter is similar to 100. The optical and near-infrared spectra taken by Magellan enable us to estimate its bolometric luminosity to be L-bol similar to 1.1 x 10(48) erg s(-1), approximately 4.5 times greater than that of the most distant quasar known to date. The black hole mass of J0131-0321 is estimated to be 2.7 x 10(9) M-circle dot, with an uncertainty up to 0.4 dex. Detailed physical properties of this high-redshift, radio-loud, potentially super-Eddington quasar can be probed in the future with more dedicated and intensive follow-up observations using multi-wavelength facilities.
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  • 2D-3D transformation of palladium and gold nanoparticles on functionalized Mo2C by multiscale simulation

    Zhao, Chenxia   Qiu, Chenglong   Deng, Shengwei   Sun, Xiang   Gao, Yijing   Cao, Yongyong   Zhuo, Han   Zhuang, Guilin   Zhong, Xing   Wei, Zhongzhe   Yao, Zihao   Wang, Jian-guo  

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  • Kernel maximum scatter difference based feature extraction and its application to face recognition

    Wang, Jian-guo   Lin, Yu-sheng   Yang, Wan-kou   Yang, Jing-yu  

    This paper formulates maximum scatter difference (MSD) criterion in the kernel-including feature space and develops a two-phase kernel maximum scatter difference criterion: KPCA plus MSD. The proposed method first maps the input data into a potentially much higher dimensional feature space by virtue of nonlinear kernel trick, and in such a way, the problem of feature extraction in the nonlinear space is overcome. Then the scatter difference between between-class and within-class as discriminant criterion is defined on the basis of the above computation; therefore, the singularity problem of the within-class scatter matrix due to small sample size problem occurred in classical Fisher discriminant analysis is avoided. The results of experiments conducted on a subset of FERET database, Yale database indicate the effectiveness of the proposed method. (C) 2008 Elsevier B.V. All rights reserved.
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  • The Effect of N-Containing Supports on Catalytic CO Oxidation Activity over Highly Dispersed Pt/UiO-67

    Zhuang, Gui-lin   Bai, Jia-qi   Zhou, Xiang   Gao, Yi-fen   Huang, Hong-liang   Cui, Hai-quan   Zhong, Xing   Zhong, Chong-li   Wang, Jian-guo  

    Investigations of the effects of the support on catalytic properties are important for heterogeneous systems. Herein, we report the preparation of highly dispersed Pt nanoparticles (NPs) in three isomorphous UiO-67-type metal-organic frameworks (MOFs), namely, pristine UiO-67, N-UiO-67, and NH2-UiO-67. Structural measurements revealed that the sizes of the Pt NPs were 4.5 nm for Pt/UiO-67 and 2.5 nm for N-UiO-67 and NH2-UiO-67. The dominant influences on the sizes of the Pt NPs are the functional groups of the support and the pore size of the MOF. Furthermore, CO catalytic oxidations were performed as a model reaction. Interestingly, the catalytic performance sequence is 5 % Pt/N-UiO-67 > 5 % Pt/UiO-67 > 5 % Pt/NH2-UiO-67. A combination of experimental measurement and DFT calculation revealed that the catalytic properties depend on not only the size of the Pt NPs but also the nature of the support.
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  • Identification of some novel AHAS inhibitors via molecular docking and virtual screening approach.

    Wang, Jian-Guo   Xiao, Yong-Jun   Li, Yong-Hong   Ma, Yi   Li, Zheng-Ming  

    Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) catalyzes the first common step in branched-chain amino acid biosynthesis. This enzyme is an important target for the design of environmental-benign herbicides. Based on the crystal structure of AHAS/sulfonylurea complex, we have carried out computational screening of the ACD-3D database in order to look for novel non-sulfonylurea inhibitors of AHAS for the first time. Three novel compounds were found to inhibit plant AHAS in vitro among 14 procured compounds. One compound showed promising activity in vivo for rape root growth inhibition bioassay. This research provided useful clues for further design and discovery of AHAS inhibitors.
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  • Application of isoxanthopterin as a new pterin marker in the differential diagnosis of hyperphenylalaninemia

    Bao, Pei-Zhong   Ye, Jun   Han, Lian-Shu   Qiu, Wen-Juan   Zhang, Hui-Wen   Yu, Yong-Guo   Wang, Jian-Guo   Gu, Xue-Fan  

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  • Optimization of warship formation air defense combat model based on dynamic scheduling of combat resources

    Ma, Liang   Wang, Jian-guo  

    Aiming at the problem of limited resources and operational time combat air defense combat, naval combat formation analysis dynamic resources scheduling needs, on the basis of the establishment of ship dynamic scheduling model of warship formation combat resources dynamic combat formation resource scheduling, the operational resources and operational objectives, relationship between reasonable allocation of resources to play the warship formation combat operations the maximum efficiency. The design of three kinds of air defense command models: centralized platform free attack mode, command mode, request attack mode of air defense strategy, put forward the dynamic scheduling hybrid algorithm for solving the model, according to the naval fleet air defense combat scenario example for simulation. The simulation results show that the air defense strategy with the request attack mode can have effects on multi-target attacks under the shared combat situation, and the hybrid algorithm based on combat resource dynamic scheduling can meet the real-time operational requirements.
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  • Optimization of warship formation air defense combat model based on dynamic scheduling of combat resources

    Ma, Liang   Wang, Jian-guo  

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