We propose a lattice Boltzmann scheme for two-dimensional complex boundaries moving in fluid flow. The hydrodynamic forces exerting on the moving boundaries are calculated based on a stress-integration method proposed before, but the extrapolation procedure is avoided, and the
stability of this model is improved. The accuracy and robustness are demonstrated by numerical simulations of a circular particle settling in a two-dimensional vertical channel. The numerical convergence is studied by varying the time-step and the dimensionless particle sizes.

Zn_1-xCo_xO (x=0.01, 0.02, 0.05, 0.10 and 0.20) diluted magnetic semiconductors are prepared by the sol-gel method. The structural and magnetic properties of the samples are studied using x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS) and superconducting quantum interference device (SQUID). The XRD patterns does not show any
signal of precipitates that are different from wurtzite type ZnO when Co content is lower than x=0.10. An EXAFS technique for the Co K-edge has been employed to probe the local structures around Co atoms doped in ZnO powders by fluorescence mode. The simulation results for the first shell EXAFS signals indicate that Zn sites can be substituted by Co atoms when Co content is lower than x=0.05. The SQUID results show that the samples (x<0.05) exhibit clear hysteresis loops at 300K, and magnetization versus temperature from 5K to 350K at H=100,Oe for the sample x=0.02 shows
that the samples have ferromagnetism above room temperature. A double-exchange mechanism is proposed to explain the ferromagnetic properties of the samples.

An epitaxial γ-Mg₂SiO₄ thin film can be a good buffer between the Si ubstrate and some oxide thin films. For high temperature superconducting multilayer structures, hopefully it can be taken as an insulating layer to
replace the widely used MgO film. To explore such possibilities, we carry out systematic studies on the influences of pressure and substrate temperature on the epitaxy of γ-Mg₂SiO₄ thin films grown on Si (100) substrates using rf magnetron sputtering with an Mg target of purity of 99.95 percent. With the
substrate temperature kept at 500°C and the pressure changing from 10Pa to 15Pa, in the XRD spectra the γ-Mg₂SiO₄ (₄₀₀) peak grows drastically while the MgO (200) peak is suppressed. Keeping the pressure at 15Pa and
increasing the temperature from 500°C to 570°C further can improve the film epitaxy, while working at 780°C and 11Pa seems to give very good
results. X-ray photoelectronic spectroscopy and Ф scan are used to characterize the stoichiometry, crystallinity, and in-plane growth of the samples.

We investigate the molecular beam epitaxy growth of metamorphic In_xGa_1-xAs materials (x up to 0.5) on GaAs substrates systematically. Optimization of structure design and growth parameters is aimed at obtaining smooth surface and high optical quality. The optimized structures have an average surface roughness of 0.9--1.8nm. It is also proven by PL measurements that the optical properties of high indium content (55%) InGaAs quantum wells are improved apparently by defect reduction technique and by introducing Sb as a surfactant. These provide us new ways for growing device quality metamorphic structures on GaAs substrates with long-wavelength emissions.