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Electron microscopy study of the sakhaite from endogenous borate deposit in Hunan, China

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Science China Earth Sciences 2004年第3期47卷 232-238页

作者： LIU Xiangwen1,2. YANG Guangming2. ZOU Huamin3, QU Jing1 & ZHAO Wenxia4 1. Graduate School, China university of geosciences,{2., China 2. test center, China university of geosciences,{2., China 3. Physics and Technology College, wuhan university, wuhan 430072. China 4. test center, Zhongshan university, Guangzhou 5102.5, China Graduate School China University of Geosciences Wuhan 430074 China test center China University of Geosciences Wuhan 430074 China Physics and Technology College Wuhan University Wuhan 430072 China test center Zhongshan University Guangzhou 510275 China

Sakhaite specimens from an endogenous borate deposit in Hunan Province, China have been studied in detail by means of transmission electron microscopy (TEM). The selected area electron diffraction (SAED) patterns obtained with different crystal zone axes show that the crystal system is cubic, with a = 1.463 nm. The convergent beam electron diffraction (CBED) patterns indicate that the point group and space group of sakhaite is m3m and Fd3m, respec-tively. The space group of synthetic sakhaite determined by Chichagov (1974) is F4132. The possible reasons why the space groups of the natural and the synthetic sakhaites are different are discussed.

关键词： sakhaite, space group, convergent beam electron diffraction (CBED).

Evaluation Method of Web Site Structure Based on Web Structure Mining

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wuhan university Journal of Natural Sciences 2003年第3A期8卷 791-796页

作者： Li Jun\|e 1 , Zhou Dong\|ru 2.1. Computer center,wuhan {2., wuhan 430072. Hubei, China 2. School of Computer,wuhan {2., wuhan 430072. Hubei,China Computer center Wuhan University Wuhan Hubei China School of Computer Wuhan University Wuhan Hubei China

The structure of Web site became more complex than before. During the design period of a Web site, the lack of model and method results in improper Web structure, which depend on the designer's experience. From the point of view of software engineering, every period in the software life must be evaluated before starting the next period's work. It is very important and essential to search relevant methods for evaluating Web structure before the site is completed. In this work, after studying the related work about the Web structure mining and analyzing the major structure mining methods (Page\|rank and Hub/Authority), a method based on the Page\|rank for Web structure evaluation in design stage is proposed. A Web structure modeling language WSML is designed, and the implement strategies for evaluating system of the Web site structure are given out. Web structure mining has being used mainly in search engines before. It is the first time to employ the Web structure mining technology to evaluate a Web structure in the design period of a Web site. It contributes to the formalization of the design documents for Web site and the improving of software engineering for large scale Web site, and the evaluating system is a practical tool for Web site construction.

关键词： web structure mining page\|rank web structure evaluation modeling language for web structure

A simple lattice Boltzmann scheme for low Mach number reactive flows

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Science China(Technological Sciences) 2006年第6期49卷 714-726页

作者： CHEN Sheng1,2. LIU Zhaohui2. ZHANG Chao2. HE Zhu2. TIAN Zhiwei2. SHI Baochang 2.& ZHENG Chuguang2.1. Technology center of wuhan Iron and Steel (Group) Company, wuhan 430080, China 2. State Key Laboratory of Coal Combustion, Hua Zhong university of Science and Technology, wuhan 43.074, China Technology center of wuhan Iron and Steel (Group) Company Wuhan China State Key Laboratory of Coal Combustion Hua Zhong University of Science and Technology Wuhan China

For simulating low Mach number reactive flows, a simple and coupled lattice Boltzmann (CLB) scheme is proposed, by which the fluid density can bear significant changes. Different from the existing hybrid lattice Boltzmann (HLB) scheme and non-coupled lattice Boltzmann (NCLB) scheme, this scheme is strictly lattice Boltzmann style and the fluid density couples directly with the temperature. Because it has got rid of the constraint of traditional thought in lattice Boltzmann scheme,on the basis of the equality among the particle speed c, the time step △t and the lattice grid spacing △x held, both c and △t can be adjusted in this scheme according to a "characteristic temperature" instead of the local temperature. The whole algorithm becomes more stable and efficient besides inheriting the intrinsically outstanding strong points of conventional lattice Boltz-mann scheme. In this scheme, we also take into account different molecular weights of species, so it is more suitable for simulating actual low Mach number reactive flows than previous work. In this paper, we simulated a so-called "counter-flow" premixed propane-air flame, and the results got by our scheme are much better than that obtained by NCLB. And the more important thing is that the exploration in this work has offered a kind of brand-new train of thought for building other novel lattice Boltzmann scheme in the future.

关键词： lattice Boltzmann, low Mach number flows, reactive flows, simulation.

Synthesis of todorokite by refluxing process and its primary characteristics

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Science China Earth Sciences 2004年第8期47卷 760-768页

作者： FENG Xionghan1, LIU Fan1, TAN Wenfeng1, LIU Xiangwen2.& HU Hongqing1 1. College of Resources and Environment, Huazhong Agricultural university, wuhan 430070, China 2. {2.ing center, China university of geosciences, wuhan 43.074, China College of Resources and Environment Huazhong Agricultural University Wuhan China testing center China University of Geosciences Wuhan China

Single phase and well-crystallined todorokite were synthesized by heating and refluxing process from birnessite as a precursor. The average chemical composition of the synthesized todorokites by refluxing for 8 h and for 2. h was Mg0.19MnO2.11(H2.)1.15 and in0.17-MnO2.10(H2.)0.88, respectively. The crystallinity of the todorokite increased and no other phase was produced with increasing refluxing period. The synthesized todorokites have the same morphologies and the similar structural characteristics with the natural todorokites and hydro-thermally synthesized samples. The chemical compositions of the synthetic tordorokites by refluxing process are close to those of todorokites synthesized by hydrothermal process, except a higher average oxidation state of Mn for the former.

关键词： todorokite,birnessite,manganese oxide,refluxing,hydrothermal,synthesis.

Pathways of birnessite formation in alkali medium

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Science China Earth Sciences 2005年第9期48卷 1438-1451页

作者： FENG Xionghan1, TAN Wenfeng1, LIU Fan1, HUANG Qiaoyun1 & LIU Xiangwen2.1. College of Resources and Environment, Huazhong Agricultural university, wuhan 430070, China 2. {2.ing center, China university of geosciences, wuhan 43.074, China College of Resources and Environment Huazhong Agricultural University Wuhan China testing center China University of Geosciences Wuhan China

Birnessite is a common weathering and oxidation product of manganese-bearing rocks. An O2.oxidation procedure of Mn(OH)2.in the alkali medium has been used to synthesize birnessite. Fast and powder X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), energy dispersed X-ray analysis (EDAX), infrared spectroscopy (IR) techniques and chemical composition analysis, Eh-pH equilibrium diagram approaches were employed to investigate the reaction process and pathways of birnessite formation. Results showed that the process of the birnessite formation could be divided into four stages: (1) forma- tion stage for hausmannite and feitknechtite, (2. stage of transformation of hausmannite and feitknechtite to buserite, (3) buserite crystal growing stage, and (4) stage of conversion of buser- ite into birnessite. Mn(OH)2.was mainly present as amorphous state only for a short initial time of oxidation reaction. In the oxidation process, buserite formed following two pathways by recrys- tallization after dissolution of the intermediates, and the transformations of the minerals de- pended on the Eh determined by the dissolved O2.concentration on their surfaces. The results are fundamental in further exploration on the mechanism of birnessite formation in the alkali medium. A great practical significance would also be expected with respect to the areas of mate- rial sciences.

关键词： birnessite, pathway of formation, reaction process, Eh-pH diagram, hausmannite, feitknechtite.

Evaluation of a Novel Bioabsorbable PRGD/PDLLA/β-TCP/NGF Composites in Repair of Peripheral Nerves

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Journal of wuhan university of Technology(Materials Science) 2009年第3期24卷 409-414页

作者：王永红李世普 Hospital Wuhan University of Technology Biomedical Materials and Engineering Research center Wuhan University of Technology

Peripheral nerve regeneration using a novel nerve conduit （PRGD/PDLLA/β TCP/NGF） was evaluated, which was made of RGD peptide modified poly{（lactic acid）-co-[（glycolic acid）-alt-（L-lysine）]} （PRGD）, poly（d,l-lactic acid）（PDLLA） and β-tricalcium phosphate （β-TCP）. And the effectiveness was compared with that of PRGD/PDLLA/β-TCP, PDLLA and autograft in terms of nerve regeneration across a gap. Both of biodegradablity and cell-biocompatibility of the novel nerve conduit were evaluated in vitro. The results show that PRGD/PDLLA/β-TCP/NGF composite ma terials have better biodegradation properties and cell affinity than PDLLA, and could promote the RSC96 Schwann cells adhesion, proliferation and growth on the surface of materials. PRGD/PDLLA/ β-TCP/NGF composite conduit was significantly superior to that of the PDLLA conduit in histological and axon morphologic index. PRGD/PDLLA/β-TCP/NGF conduit is more beneficial to nerve regeneration than PDLLA conduit. The biodegradable PDLLA/PRGD/β-TCP/NGF conduit has a good biocompatibility with rats tissue and it could effectively promote the nerve regeneration after bridging sciatic nerve defect of rats, the effect is as good as that of the autograft nerve, significantly superior to the PRGD/PDLLA/β-TCP conduit and PDLLA conduit. PDLLA/PRGD/β-TCP/NGF composite conduit is a potential ideal conduit.

关键词： peripheral nerve nerve conduit PDLLA/PRGD/β-TCP/NGF composite regeneration

The mechanism of breakdown in laminar-turbulent transition of a supersonic boundary layer on a flat plate-temporal mode

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Science China(Physics,Mechanics & Astronomy) 2005年第5期48卷 614-625页

作者： HUANG Zhangfeng 1, CAO Wei 1,2.& ZHOU Heng 1,2.1. Department of Mechanics, Tianjin university, Tianjin 300072. China 2. Liu-Hui center of Applied Mathematics, Nankai university and Tianjin university, Tianjin 300072. China Department of Mechanics Tianjin University Tianjin China Liu-Hui center of Applied Mathematics Nankai University and Tianjin University Tianjin China

Temporal mode direction numerical simulation has been done for the transition of a supersonic boundary layer on a flat plate with Mach number 4.5. Analysis of the result showed that during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbances,when they became larger,led to a remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.

关键词： supersonic boundary layer, transition, breakdown.

Lipschitz continuity of best approximations and Chebyshev centers

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Chinese Science Bulletin 1998年第3期43卷 185-188页

作者： LI Chong 1 and WANG Xinghua 2.1. center for Mathematical Sciences, Zhejiang university, Hangzhou 31002., China 2. Department of Mathematics, Hangzhou university, Hangzhou 31002., China center for Mathematical Sciences Zhejiang University Hangzhou China Department of Mathematics Hangzhou University Hangzhou China

The Lipschitz continuity results are given for best approximations and Chebyshev centers. Consequently, the open problem presented by Septycki and Vleck is solved completely.

关键词： best approximation Chebyshev center uniform convexity.

Chitosan——L-Lactic Acid Scaffold for the Regeneration of Peripheral Nerve and Its NGF Release Properties

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Journal of wuhan university of Technology(Materials Science) 2009年第6期24卷 961-964页

作者：徐海星 Department of Pharmaceutical Engineering School of Chemical EngineeringWuhan University of Technology

Chitosan—L-lactic acid composite scaffold for the regeneration of peripheral nerve is obtained by grafting L-lactic acid onto the amino groups in chitosan with combined vacuum freezer drier. The composite scaffold was characterized by ATR-FTIR and SEM. The scaffold has a better graft efficiency and has a dense inner layer and a loose outer layer with porous structure, and the pore size is about 100 μ*** NGF release properties of the scaffold were investigated. The experimental results showed that, at the 1st day, 15.2.ng of NGF on average was released from the scaffold. From day 2.to day 10, the release rate obviously slowed down and 1.64 ng of NGF was released on average every day. After 10 days, the release rate was slower and 10.3 ng of NGF was released on average every day. After 60 days, NGF could also maintained a certain concentration. These properties show that the scaffold is a better carrier for NGF which can be more advantageous to the regeneration of the damaged peripheral nerve. As a result, this composite scaffold would be an ideal candidate for the regeneration of damaged peripheral nerve.

关键词： chitosan L-lactic acid peripheral nerve NGF release properties