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41.
Ilya B. Simanovskii Antonio Viviani Jean-Claude Legros 《European Journal of Mechanics - B/Fluids》2008,27(5):632-641
The nonlinear thermocapillary and buoyant-thermocapillary flows in a three-layer system, filling a closed cavity and subjected to a temperature gradient directed along the interfaces, are investigated. The nonlinear simulations of convective regimes are performed by the finite-difference method. The process of transition of unicell structures into multicell structures is studied. 相似文献
42.
François Dunlop Jacques Magnen Vincent Rivasseau Philippe Roche 《Journal of statistical physics》1992,66(1-2):71-98
We prove that in a two-dimensional Gaussian SOS model with a small attractive potential the height of the interface remains bounded no matter how small the potential is; this is in sharp contrast with the free situation in which the interface height diverges logarithmically in the thermodynamic limit. 相似文献
43.
Chemical reactions in cracks of aluminum crystals: Generation of hydrogen from water 总被引:1,自引:0,他引:1
Masao Watanabe 《Journal of Physics and Chemistry of Solids》2010,71(9):1251-1258
Pure hydrogen is generated from water molecules which are dissociated by specific aluminum particles called activated Al powder. Reaction mechanism of Al atoms with H2O molecules is investigated in micro-cracks of Al crystals. It becomes obvious that hydrogen atoms exist in Al crystal mainly in states of AlH3 hydrides. It is concluded that virgin walls of micro-cracks right after the creation provide virtually Al radical atoms of (Al−) or (Al=) with one or two free bonds, which react with H2O molecules via surface diffusion resulting in producing AlH3 and eventually in producing H2. The production of H2 seems to be a result of micro-tribochemical reactions in cracks, which are produced by mechanical crushing of Al crystals in water; tips of cracks as stress-focused points play a major role to create AlH3. Peculiar environments of nano-spaces in micro-cracks surrounded by reactive atoms enable us to realize unusual chemical reactions at low temperatures as exemplified in the present paper. 相似文献
44.
We consider numerically the depinning transition in the random-field Ising model. Our analysis reveals that the three and four dimensional model displays a simple scaling behavior whereas the five dimensional scaling behavior is affected by logarithmic corrections. This suggests that d = 5 is the upper critical dimension of the depinning transition in the random-field Ising model. Furthermore, we investigate the so-called creep regime (small driving fields and temperatures) where the interface velocity is given by an Arrhenius law. 相似文献
45.
Photocatalytic activity of Nb2O5/SrNb2O6 heterojunction on the degradation of methyl orange 总被引:1,自引:0,他引:1
Jingcheng Xing Zhichao Shan Jianjiang Bian Wendeng Wang 《Journal of Physics and Chemistry of Solids》2008,69(1):23-28
The pure SrNb2O6 powders were prepared at 1400 °C by a conventional solid-state method and characterized by X-ray powder diffraction and UV-vis diffuse reflection spectrum. The powders of Nb2O5 and SrNb2O6 were ball-milled together and annealed to form the Nb2O5/SrNb2O6 composite. Photocatalytic activities of the composites were investigated on the degradation of methyl orange. The results show that the proportion of Nb2O5 to SrNb2O6 and the annealing temperature greatly influence the photocatalytic activities of the composites. The best photocatalytic activity occurs when the weight proportion of Nb2O5 to SrNb2O6 is 30% and the annealing temperature is 600 °C. The tremendously enhanced photocatalytic activity of the Nb2O5/SrNb2O6 composite compared to Nb2O5 or SrNb2O6 is ascribed to the heterojunction effect taking place at the interface between particles of Nb2O5 and SrNb2O6. The powders also show a higher photocatalytic activity than commercial anatase TiO2. 相似文献
46.
Numerical simulations are performed to study the interaction of a solidification front with an embedded particle. A sharp-interface method is used to track both the phase boundary and the particle. The solidification front dynamics is fully coupled with particle motion. The main objective of the paper is to distinguish the role played by the premelted layer between the solidification front and the particle in determining conditions for particle engulfment. Results are obtained by assuming a premelted layer exists in the gap between the particle and the solidification front and compared to those assuming no premelted layer. In the absence of a premelted layer, arbitrary cut-off values for particle-front gap thickness need to be invoked in order to define the critical velocity for which the pushing–engulfment transition occurs. When a premelted layer is assumed to exist, the prediction of the critical velocity is determined solely from the dynamics of the coupled front–particle interaction. In addition, model predictions for the critical velocity based on a steady-state heat transfer analysis are shown to differ from that when the full dynamics of the phase boundary are taken into account. 相似文献
47.
SrTiO3/BaZrO3 heterofilms as buffer layers are deposited on (0 0 1) MgO substrates by an RF-sputtering technique. The atomic structure and the defect configuration at the interfaces are investigated by means of aberration-corrected high-resolution transmission electron microscopy. At the BaZrO3/MgO interface, two types of interfacial structures, MgO/ZrO2-type and MgO/BaO-type, are observed. Antiphase boundaries and dislocations are found at the BaZrO3/MgO interface. The formation of these lattice defects is discussed in terms of film growth and structural imperfections of the substrate surface. At the SrTiO3/BaZrO3 interface, a high density of misfit dislocations is observed with different configurations. The formation of these dislocations contributes both to the relaxation of the large misfit strain and to stopping of the further propagation of lattice defects which are formed in the BaZrO3 layer into the SrTiO3 layer. 相似文献
48.
The growth and dissolution rates of borax decahydrate have been measured as a function of supersaturation for various particle sizes at different temperature ranges of 13 and 50 °C in a laboratory-scale fluidized bed crystallizer. The values of mass transfer coefficient, K, reaction rate constant, kr and reaction rate order, r were determined. The relative importances of diffusion and integration resistance were described by new terms named integration and diffusion concentration fraction. It was found that the overall growth rate of borax decahydrate is mainly controlled by integration (reaction) steps. It was also estimated that the dissolution region of borax decahydrate, apart from other materials, is controlled by diffusion and surface reaction. Increasing the temperature and particle size cause an increase in the values of kinetic parameters (Kg, kr and K). The activation energies of overall, reaction and mass transfer steps were determined as 18.07, 18.79 and 8.26 kJmol−1, respectively. 相似文献
49.
Hui Luo Dr. Kejun Bu Dr. Yanfeng Yin Dong Wang Cuimi Shi Songhao Guo Tonghuan Fu Jiayuan Liang Bingyan Liu Dr. Dongzhou Zhang Prof. Liang-Jin Xu Prof. Qingyang Hu Prof. Yang Ding Prof. Shengye Jin Prof. Wenge Yang Prof. Biwu Ma Prof. Xujie Lü 《Angewandte Chemie (International ed. in English)》2023,62(37):e202304494
Low-dimensional (low-D) organic metal halide hybrids (OMHHs) have emerged as fascinating candidates for optoelectronics due to their integrated properties from both organic and inorganic components. However, for most of low-D OMHHs, especially the zero-D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents efficient charge transfer at the hybrid interfaces and thus limits their further tunability of optical and electronic properties. Here, using pressure to regulate the interfacial interactions, efficient charge transfer from organic ligands to metal halides is achieved, which leads to a near-unity photoluminescence quantum yield (PLQY) at around 6.0 GPa in a 0D OMHH, [(C6H5)4P]2SbCl5. In situ experimental characterizations and theoretical simulations reveal that the pressure-induced electronic coupling between the lone-pair electrons of Sb3+ and the π electrons of benzene ring (lp-π interaction) serves as an unexpected “bridge” for the charge transfer. Our work opens a versatile strategy for the new materials design by manipulating the lp-π interactions in organic–inorganic hybrid systems. 相似文献
50.
Avishek Ghosh Marc Smits Maria Sovago Jens Bredenbeck Michiel Müller Mischa Bonn 《Chemical physics》2008,350(1-3):23
We report investigations of the vibrational dynamics of water molecules at the water–air and at the water–lipid interface. Following vibrational excitation with an intense femtosecond infrared pulse resonant with the O–H stretch vibration of water, we follow the subsequent relaxation processes using the surface-specific spectroscopic technique of sum frequency generation. This allows us to selectively follow the vibrational relaxation of the approximately one monolayer of water molecules at the interface. Although the surface vibrational spectra of water at the interface with air and lipids are very similar, we find dramatic variations in both the rates and mechanisms of vibrational relaxation. For water at the water–air interface, very rapid exchange of vibrational energy occurs with water molecules in the bulk, and this intermolecular energy transfer process dominates the response. For membrane-bound water at the lipid interface, intermolecular energy transfer is suppressed, and intramolecular relaxation dominates. The difference in relaxation mechanism can be understood from differences in the local environments experienced by the interfacial water molecules in the two different systems. 相似文献