Papers by Author: Jun Ming Li

Abstract: The growth of microarc oxidation (MAO) coatings on aluminum substrates was controlled by different mono-component solutions, involving (NaPO₃)₆, Na₃PO₄, Na₂SiO₃ and Na₂MoO₄ aqueous electrolyte. The results show that (NaPO₃)₆ solution can accelerate the growth of MAO coating, revealed by the maximum coating thickness of 12.1 μm; and meanwhile, Na₂SiO₃ solution favors the doping of solute elements during MAO, suggested by 10.75 at.% Si in coating. Furthermore, the variety of mono-component solution also affects the porous structure of MAO coating. It is assumed that the property of coating/solution interface is influenced by solution variety, while the interfacial property determines the solidification of ceramic particles and the adsorption of solute anion during microarc discharge, thus realizing controlled growth of MAO coating.

Abstract: Surface and porous characteristics of spray dried hydroxyapatite microspheres were studied by surface area and pore size analyzer, field-emission scanning electron microscope, Fourier transform infrared spectroscope, etc. The results indicated dehydration did not happened for those samples calcined at 1000°C, and the intensity of OH- absorption bands increased. Hydroxyapatite microspheres were composed of near-spherical crystals with the diameter of 20-50nm. Besides, it was interesting to find that hydroxyapatite crystals formed small aggregate firstly during drying, and then the small aggregate united together and formed particles with spherical structure.

Abstract: Effect of crystals size, surface area, pore size and porosity of hydroxyapatite microspheres on the loading ability of bovine serum albumin was studied in this paper. The surface morphology, specific surface area and porosity of hydroxyapatite microspheres were characterized by scanning electron microscope, specific surface area and pore size analyzer, respectively. The concentration of BSA in aqueous solutions both before and after adsorption was determined by ultraviolet-visible spectrophotometer. The results indicated that the adsorption behavior of bovine serum albumin appeared to obey the Langmuir-type isotherm model. Fast adsorption appeared at the beginning, and then decreased gradually. Hydroxyapatite microspheres calcined at 600°C had the maximum capacity, and those calcined at 800°C showed lower adsorption ability. The loading ability of hydroxyapatite microspheres depended on its crystal size, specific surface area, pore size and porosity, etc.