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地下开采斜坡整体稳定性评价分析

世界有色金属 2024年第5期 121-123页

作者：王天敏贵州省有色金属和核工业地质勘查局物化探总队贵州都匀558000

斜坡稳定性是地下开采过程中的一个重要问题,对于确保开采安全具有重要意义。本文通过对地下开采斜坡稳定性的分析,旨在提供对该问题的深入理解。以瓮安磷矿生物群科学考察区边坡为例,通过现场勘查,与室内研究,结合定性与定量分析对开... 详细信息

斜坡稳定性是地下开采过程中的一个重要问题,对于确保开采安全具有重要意义。本文通过对地下开采斜坡稳定性的分析,旨在提供对该问题的深入理解。以瓮安磷矿生物群科学考察区边坡为例,通过现场勘查,与室内研究,结合定性与定量分析对开采边坡危岩体稳定性做出分析,并给出了相应的处理措施建议。通过本文的研究,能够更好地理解地下开采斜坡稳定性的问题,并为地下开采的安全提供有效的参考依据。

关键词：露天边坡危岩体稳定性

Study of Surface Cell Madelung Constant and Surface Free Energy of Nanosized Crystal Grain

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Chinese Journal of Structural Chemistry 2005年第12期24卷 1369-1374页

作者： ZHANG Wei-Jia wang tian-min CUI min School of Science Beijng University of Aeronutics and Astronautics Beijing 100083 China

Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface analysis and study dynamics of crystal nucleus growth. A new approximative expression of surface energy and relevant thermodynamic data was used in this calculation. A new formula and computing method for calculating the Madelung constant a of any complex crystals is proposed, and surface free energies and surface electrostatic energies of nanosized crystal grains as well as Madelung constant of some complex crystals are theoretically calculated in this paper. The surface free energy of nanosized crystal grain TiO2 and surface electrostatic energy（absolute value） of nanosized crystal grain α-A12O3 are found to be the biggest among other crystal grains.

关键词： Madelung constant surface free energy nanosized crystal grain

Magnetic and Optical Properties of the TiO_2-Co-TiO_2 Composite Films Grown by Magnetron Sputtering

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Chinese Journal of Aeronautics 2007年第2期20卷 162-167页

作者： LIU Fa-min DING Peng SHI Wei-mei wang tian-min Department of Physics School of Sciences Beijing University of Aeronautics and Astronautics Beijing 100083 China

The TiO2-Co-TiO2 sandwich films were successfully grown on glass and silicon substrata making alternate use of radio frequency reactive magnetron sputtering and direct current magnetron sputtering. The structures and properties of these films were identified with X-ray diffraction （XRD）, Raman spectra and X-ray photoemission spectra （XPS）. It is shown that the sandwich film consists of two anatase TiO2 films with an embedded Co nano-film. The fact that, when the Co nano-film thickens, varied red shifts appear in optical absorption spectra may well be explained by the quantum confinement and tunnel effects. As for magnetic properties, the saturation magnetization, remnant magnetic induction and coercivity vary with the thickness of the Co nano-films. Moreover, the Co nano-film has a critical thickness of about 8.6 mn, which makes the coercivity of the composite film reach the maximum of about 1413 Oe.

关键词： TiO2-Co-TiO2 sandwich films surface structure and properties optical and magnetic properties

First-principle Calculations of V/Fe Doped Anatase TiO_2

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Chinese Journal of Aeronautics 2006年第B12期19卷 162-166页

作者： CAO Hong-hong CHEN Qiang wang tian-min School of Science Beijing University of Aeronautics and Astronautics Beijing 100083 China

The electronic structures of the titanium dioxide（TiO2） doped with V and Fe were analyzed by using first-principle calculations based on the density functional theory（DFT） with the full potential linearized augmented plane wave method （FP-LAPW）. The fully optimized structure and the relaxation introduced by impurity were obtained by minimizing the total energy and atomic forces. The unit cell of the V-doped anatase TiO2 is smaller than that of the non-doped one, but for the Fe-doped one, the case is just the opposite. It is found that the apical Ti-O and impurity-O bond lengths of the V/Fe-doped anatase TiO2 are greater than those of the non-doped structure, but smaller for the equatorial bond length. Through the band structures and the density of states, the V-doped TiO2 is shown to be a kind of half-metal, while the Fe-doped TiO2 a kind of metal. The magnetic moments of the V/Fe-doped system are mainly generated by the dopants. The results may be helpful for us to understand the experimental outcome of this system.

关键词： first-principle FP-LAPW DMS anatase electronic properties

Microstructure and Optical Characterization of Magnetron Sputtered NbN Thin Films

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Chinese Journal of Aeronautics 2007年第2期20卷 140-144页

作者： DU Xin-kang wang tian-min wang Cong CHEN Bu-liang ZHOU Long School of Science Beijing University of Aeronautics and Astronautics Beijing 100083 China Mechanical Engineering College Shifiazhuang 050003 China Academy of Space Technology Beijing 100029 China

Some fundamental studies on the preparation, structure and optical properties of NbN films were carried out. NbN thin films were deposited by DC reactive magnetron sputtering at different N2 partial pressures and different substrate temperatures ranging from -50℃ to 600℃. X-ray diffraction analysis （XRD） and scanning electron microscopy （SEM） were employed to characterize their phase components, microstructures, grain sizes and surface morphology. Optical properties inclusive of refractive indexes, extinction coefficients and transmittance of the NbN films under different sputtering conditions were measured. With the increase in the N2 partial pressure, 6-NbN phase structure gets forming and the grain size and lattice constant of the cubic NbN increasing. The deposited NbN film has relatively high values of refractive index and extinction coefficient in the wavelength ranging from 240 nm to 830 nm. Substrate temperature exerts notable influences on the microstructure and optical transmittance of the NbN films. The grain sizes of the 6-NbN film remarkably increase with the rise of the substrate temperature, while the transmittance of the films with the same thickness decreases. Ultra-fine granular film with particle size of several nanometers forms when the substrate is cooled to -50℃, and a remarkable augmentation of transmittance could be noticed under so low a temperature.

关键词： reactive magnetron sputtering NbN thin film microstructure optical properties

Electrolytic Passivation of Nitinol Shape Memory Alloy in Different Electrolytes

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Chinese Journal of Aeronautics 2006年第B12期19卷 113-118页

作者： SU Xiang-dong wang tian-min HAO Wei-chang HE Li Center of Materials Physics and Chemistry Beijing University of Astronautics and Aeronautics Beijing 100083 China Guizhou Academy of Science Guiyang 55000 China

The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl^- ion concentrations. The results demonstrate that the Cl^- ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples passivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those passivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti：Ni = 9.01：1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface.

关键词： NiTi alloy Cl^- ion corrosion electrolytic passivation TiO2 coating

Preparation and Photocatalytic Activity of ZnO/Fe_(2)O_(3)Nanorod Arrays and ZnO/NiO Nanotube Arrays

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Chinese Physics Letters 2012年第3期29卷 187-189页

作者： CUI Yin-Fang wang Cong WU Su-Juan LIU Yu wang tian-min Center for Condensed Matter and Materials Physics Department of PhysicsBeihang UniversityBeijing 100191

ZnO/Fe_(2)O_(3) nanorod arrays(NRs)and ZnO/NiO nanotube arrays(NTs)are synthesized on Si substrates by using a facile two-step growth *** absorption spectrum of the ZnO/Fe_(2)O_(3) NRs shows significant absorption in the visible light *** photocatalytic properties are evaluated by the degradation of methylene blue(MB).It is found that the ZnO/Fe_(2)O_(3) NRs display higher photocatalytic activity than the ZnO/NiO nanotube arrays under UV-vis light *** is most likely attributed to an effective separation of photoelectrons and holes.

关键词： ZnO/NiO absorption

Influence of Fe in the local Structure of Perovskite Compound La_(2/3)Ca_(1/3)Fe_(1-x)Mn_(x)O_(3)

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Chinese Physics Letters 2000年第6期17卷 446-447页

作者： WEI Long wang Yun-Bo wang Hui-Yao YUE Yong wang tian-min ZHANG tian-Bao CAO Guo-Hui Institute of High Energy Physics Chinese Academy of SciencesBeijing 100080 School of Sciences Beijing University of Aeronautics and AstronauticsBeijing 100083 Department of Metal Physics Beijing University of Science and TechnologyBeijing 100083

The ceramic samples with nominal composition of La_(2/3)Ca_(1/3)Fe_(1-x)Mn_(x)O_(3)(0.01≤x≤0.20)were prepared by solid state reaction *** effect of Fe doping on the Mn site was measured by the positron annihilation technique and M'dssbauer *** doping,no appreciable structure change and electronic structure change in Mn-O plane were observed in the series of *** M6ssbauer parameters show that the iron probe has stable 3+valance with the high spin state in all ***,by examining the shape of the spectra,the tendency can be found that the isomer shift and quadruploe splitting increase with the increasing Fe+3 *** phenomenon shows the local lattice distortion and the localization of d-electrons with the increasing Fe-doping content.

关键词： local doping structure

Jujuboside A inhibits oxidative stress damage and enhances immun-omodulatory capacity of human umbilical cord mesenchymal stem cells through up-regulating IDO expression

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Chinese Journal of Natural Medicines 2022年第7期20卷 494-505页

作者： CHEN Ji-Cong XIAO Hong-He ZHANG Qiang KONG Liang wang tian-min tian Yu ZHAO Yu-Meng LI He tian Jin-ming wang Cui YANG Jing-Xian School of Pharmacy Liaoning University of Traditional Chinese MedicineDalian 116600China Department of Neurology Dalian Municipal Central Hospital Affiliated to Dalian Medical UniversityDalian 116033China

Impaired immunomodulatory capacity and oxidative stress are the key factors limiting the effectiveness of mesenchymal stem cell transplantation *** present study was aimed to investigate the effects of jujuboside A(JuA)on the protective effect and immunomodulatory capacity of human umbilical cord mesenchymal stem cells(hUC-MSCs).Hydrogen peroxide was used to establish an oxidative damage model of hUC-MSCs,while PBMCs isolated from rats were used to evaluate the effect of JuA pre-treatment on the immunomodulatory capacity of ***,Hoechst 33258 staining,lactate dehydrogenase test,measurement of malondialdehyde,Western blot,high-performance liquid chromatography;and flow cytometry were *** results indicated that JuA(25μmol·L−1)promoted the proliferation of hUC-MSCs,but did not affect the differentiating capability of these *** pre-treatment inhibited apoptosis,prevented oxidative damage,and up-regulated the protein expression of nuclear factor-erythroid factor 2-related factor 2 and heme oxygenase 1 in hUC-MSCs in which oxidative stress was induced with *** addition,JuA pre-treatment enhanced the inhibitory effect of hUC-MSCs against abnormally activated PBMCs,which was related to stimulation of the expression and activity of indoleamine 2,*** conclusion,our results demonstrate that JuA pre-treatment can enhance the survival and immunomodulatory ability through pathways related to oxidative stress,providing a new option for the improvement of hUC-MSCs in the clinical setting.

关键词： Human umbilical cord mesenchymal stem cells Jujuboside A Immunomodulation Oxidative stress Indoleamine 2,3-dioxygenase