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71.
The transport properties of a single-wall ZnO nanotube contacted with two Au (Al or Cu ) electrodes are investigated by a theoretical approach. Our results suggest the contact resistance for ZnO nanotube connected with Au electrodes is the largest one as compared with Al and Cu acting as electrodes. The local density of states (LDOS) near the ZnO nanotube/Cu(Al) interface shows the strong electronic interaction. Also shown is that for Au–ZnO system, we can observe a best rectifying performance, the next is the Al–ZnO system, and the third is Cu–ZnO system. This rectification is also fully rationalized by the calculated transmission spectra, the spatial distribution of the lowest unoccupied molecular orbital and highest occupied molecular orbital states, and the electrostatic potential distribution. 相似文献
72.
It is well-known that nano-systems can have properties which are distinctly different from macroscopic systems. In this study we point out the following specific behaviour: if the particle number is decreased so that the size of the system is in the nanometer-realm, new effects emerge which reflect certain features of biological systems although the system is inorganic in nature. This behaviour is shown by realistic molecular dynamics calculations in connection with aluminum-nanoclusters at various temperatures. The clusters can transform without external influence from a metastable into a stable state, and there can be more than one stable state, that is, we observe a bifurcation in the sense of chaos-theory. The stable states can differ in both the atomic structure and the outer shape. 相似文献
73.
74.
The inhibition of aluminium in 0.5 M H2SO4 by extracts of Spondias mombin L. was investigated using the standard gravimetric technique at 30–60 °C. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition. It was found that the S. mombin L. extract acts as an inhibitor for acid-induced corrosion of aluminium. Inhibition efficiency (%I) of the extract increased with an increase in concentration of the S. mombin L. extract but decreased with temperature. Furthermore, inhibition efficiency (%I) synergistically increased on addition of potassium iodide. Inhibitor adsorption characteristics were approximated by Langmuir adsorption isotherm at all the concentrations and temperatures studied. The mechanism of physical adsorption is proposed from the trend of inhibition efficiency with temperature and from the calculated values of Gibbs free energy, activation energy and heat of adsorption. Quantum chemical calculations were performed using the density functional theory at B3LYP/6-31G (d) level of theory to find out whether a clear link exists between the inhibitive effect of the extract and the electronic properties of its main constituents. 相似文献
75.
76.
Wang Chang-biao Tu Jian-nan Jian Hua-bei Sun Yan 《International Journal of Infrared and Millimeter Waves》1986,7(7):1005-1035
The kinetic theory based on the expansion of local field in the guiding center coordinate system, presented by paper[1]–[3], has successfully developed into a theoretical system. The mathematical background and physical explanation of setting up the guiding center coordinate system is expounded in the paper. By using the methods of the guiding center and waveguide coordinate systems respectively, the same dispersion equations for interaction of an axially symmetrical single momentum electron beam with TEmn field in the circular waveguide are rigorously derived. A number of mistakes in paper[4] are indicated as well. 相似文献
77.
In a previous paper we considered an extension of the hard hexagon model to a solvable two-dimensional lattice gas with at most two particles per pair of adjacent sites. Here we use various mathematical identities (in particular Gordon's generalization of the Rogers-Ramanujan relations) to express the local densities in terms of elliptic functions. The critical behavior is then readily obtained.Supported in part by the National Science Foundation Grant MCS 8201733. 相似文献
78.
For the weakly coupled lattice
3
6
theory in a hierarchical model approximation a nonperturbative renormalization group analysis in the spirit of Gawedzki and Kupiainen is performed to study the flow of the effective actions. We deduce a domain of attraction to the tricritical (Gaussian) fixed point. The two relevant coupling constants of the problem are controlled by analytic continuation to complex domains, tracing their images under the renormalization group iterations. 相似文献
79.
80.
契伦柯夫自由电子激光可以产生远红外相干受激辐射。本文建立了契伦柯夫自由电子激光的动力学理论并详细研究了初始信号频率,电子束电压和束—介质膜间隙对器件性能的影响。与自由电子激光,回旋自谐振脉塞比较,指出了短波契伦柯夫自由电子激光的几个显著特点。 相似文献