Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field.We show,in this paper,that the implantation of an impurity ion at the center can either enhance or suppress such transitions,depending on whether it is an acceptor or a donor ion.     

Near-saturation (P,ρ,T) and vapor-pressure measurements of NH3, and liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements of NH3+H2O mixtures

Near-saturation pressure, density, and temperature (P,ρ,T) and vapor-pressure measurements for NH₃ are reported over a temperature range from 279 to 392 K. Liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements for two standard mixtures of NH₃+H₂O (x_NH3=0.8360 and 0.9057 mole fraction) are reported over a temperature range from 280 to 379 K and at pressures to 7.7 MPa. These data are compared to literature data and correlations and agree within ±3% for bubble-point pressures, ±0.005 g/cm³ for liquid densities, and ±0.0011 g/cm³ for vapor densities. A consistent data set for equation-of-state optimization at high concentrations of NH₃ is proposed.     

Excitation energy-transfer processes between two trimers in C-phycocyanin hexamer from the cyanobacterium Anabaena variabilis. Investigation by group theory and time-resolved fluorescence spectroscopy

We have employed group theory and picosecond time-resolved fluorescence isotropy and anisotropy spectroscopy methods to explore the excitation transfers within an isolated C-phycocyanin (C-PC) hexamer (αβ)₆^PCL²⁷_RC, situated at the end of the rod proximal to the core of the pycobilisome (PBS) in the cyanobacterium Anabaena variabilis. The group-theory results imply that excitation energy transfer between two trimers occurs between the lowest exciton level of each trimer. The excitation energy-transfer process might occur at a rate of 10–20 ps, and it may be described by an exciton hopping-like Förster transfer mechanism. Dynamic components of 45–50 ps are assigned to the excitation transfer from β₁₅₅-PCB chromophores to the exciton states of dimers, which consist of two neighbouring monomers of the same trimer in an isolated C-PC hexamer.     

The Tafel–Heyrovsky route in the kinetic mechanism of the hydrogen evolution reaction

The examination of the dependence of surface coverage on overpotential for the kinetic mechanism of the hydrogen evolution reaction (HER) through the Volmer–Heyrovsky route shows that, under certain conditions, the Tafel re-adsorption can be produced. On this basis, the HER could be described with the contribution of Tafel and Heyrovsky elementary steps. The present communication derives and analyses the kinetic mechanism of the HER for the Tafel–Heyrovsky route, under Frumkin adsorption conditions.     

Thermomechanical postbuckling of composite laminated cylindrical shells with local geometric imperfections

The effect of local geometric imperfections on the buckling and postbuckling of composite laminated cylindrical shells subjected to combined axial compression and uniform temperature loading was investigated. The two cases of compressive postbuckling of initially heated shells and of thermal postbuckling of initially compressed shells are considered. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of the nonlinear prebuckling deformation, the nonlinear large deflection in the postbuckling range and the initial geometric imperfection of the shell. The analysis uses a singular perturbation technique to determine buckling loads and postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of cross-ply laminated cylindrical shells with or without initial local imperfections, from which results for isotropic cylindrical shells follow as a limiting case. Typical results are presented in dimensionless graphical form for different parameters and loading conditions.     

BASIC EQUATIONS, THEORY AND PRINCIPLE OF COMPUTATIONAL STOCK MARKET (Ⅰ)——BASIC EQUATIONS

This paper studies computational stock market by using network model and similar methodology used in solid mechanics. Four simultaneous basic equations, i.e., equation of interest rate and amount of circulating fund, equations of purchasing and selling of share, equation of changing rate of share price, and equation of interest rate, share price and its changing rate, have been established. Discussions mainly on the solution and its simple applications of the equation of interst rate and amount of circulating fund are given. The discussions also involve the proof of tending to the equilibrium state of network of stock market based on the time discrete form of the equation by using Banach theorem of contraction mapping and the influence of amount of circulating fund with exponential attenuation due to the decreasing of banking interest rate.     

域外奇源分布法场点解的唯一性

应用奇源解的核函数沿距离递减的条件和积分不等式,可证这类奇源在凸域外分布只要满足以它产生的响应来表达的边界条件时,所引起相应的域内场点解是唯一的。文中给出这类奇源的部分例子,如Kelvin的点力,点圆力偶(PRC)等。并给出PRC分布解回转体扭转问题的场点解的唯一性证明作为应用例。     

Cyclotron Resonance of an Interface Magnetopolaron at Finite Temperatures

Taking into account the interaction of an electron with both bulk longitudinal-optical (LO) and interface-optical (IO) phonons, the cyclotron resonance of an interface magnetopolaron at finite temperatures is investigated by using the generalized Larsen perturbation-theory method. It is shown that the absorption and emission resonance must be considered at the same time at finite temperatures. The results also show the important role played by the electron-IO phonon interaction. For the GaAa/GaSb structure, splitting of the cyclotron resonance spectrum and temperature dependence of the threefold splitting cyclotron resonance mass of the magnetopolaron in the resonant magnetic field region are studied.     

Resonant Frequency of Impurity Polaron in a Quantum Well

It is shown that the resonant frequency ω_c^* of a magnetopolaron bound to a Coulomb impurity in a GaAs/Ga_1-xAl_x AS quantum well is lower than that oflongitudinal optical (LO) phonons owing to the effect of the Coulomb potential. Using MacDonald method to treat the Coulomb potential we come to the conclusion that ω_c^* is really below the frequency of LO phonons but not "pinning" at a frequency near that of TO phonons.