Papers by Author: Ling Hong Guo

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Authors: Shan Shan Wei, Yi Ping Tian, Qiang Cheng, Hui Li, Ling Hong Guo
Abstract: Calcium polyphosphate (CPP) bioceramics with different Ca/P ratios were fabricated. It was shown that the contents of CPP in the sintered ceramics decrease with the increasing Ca/P ratios (0.5-1.0) of the precursors. The higher the Ca/P ratios of precursors were, the more complex the phases of polymerization were. The compressive strengths of ceramics sintered at the same temperature showed a linear decreasing tendency with the increasing Ca/P ratio.
Authors: Yi Ping Tian, Shan Shan Wei, Hui Li, Ling Hong Guo
Abstract: Bioactive porous surface on metal implants are benefit for forming the continuous interface with “mechanical interlocking” and “chemical bonding” between implants and bones. In the present study, the main attention was concentrated on fabricating a porous bioactive surface on Ti substrate. Porous surface was first fabricated by two-step etched. Then thin HA coating was deposited on the pre-treated porous Ti surface by sol-gel method and immediately sintered at 500°C for 1 hour. The structure and morphology of HA coating formed on the porous surface were characterized by thin-film X-ray diffrac- tion and scanning electronic microscopy, respectively. Rietveld method and Warren-Averbach Fourier Transfer Analysis were employed to determine the lattice parameters, crystallite size and micro-strain of HA coating. The SEM results indicated that an interconnecting porous surface with cancellous structure and mean diameter about 1/m was etched on the Ti substrate, and the surface was covered by a thin particle coating. The TF-XRD results testified that the thin coating was poor crystalline HA.
Authors: Shan Shan Wei, Yi Ping Tian, Hui Li, Ling Hong Guo
Abstract: Structure parameters of minerals in human bone, bioapatite, are very important for biomaterials. In situ micro-XRD and Rietveld structure refinement were used to extract subtle structure information of human ribs. Rietveld refinement testified that lattice parameters, crystallite size and microstrain for cortical and cancellous bones were significant difference. Anisotropic crystallite sizes of human rib showed preferential growth of apatite along c-axis and the graded variation at radial direction of bone axis. The variations of the subtle structures of bioapatite, such as, P occupancy and P-O2 bond length, as well as distortion index of P-O tetrahedron, demonstrated the tendency of mineralization and the content of CO3 2- in human ribs.
Authors: Hong Hui Zhou, Hui Li, Ling Hong Guo
Abstract: Calcium-deficient hydroxylapatite (CDHA) powders with Ca/P ratios from1.5 to 1.67 were synthesized by wet-chemical method. Rietveld structure refinement was performed on the X-ray diffraction data and Fourier transform infrared spectroscopy was used to characterize molecular and crystal structure of CDHA. With the decrease of Ca/P ratio, the crystallite size and crystallinity decreased, but the acid phosphate content and amount of vacancies in hydroxyapatite hexagonal structure increased. The disorder of CDHA structure increase indicated calcium-deficiency and HPO4 replacement resulted in disorder of crystal in apatite structure. The more calcium is deficient, the more disorder or imperfect in CDHA structure
Authors: Ling Hong Guo, Mei Huang, Yang Leng, J.E. Davies, Xing Dong Zhang
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