当前位置：TEM Studies of OCP/HA transformation and OCP in bone minerals
TEM Studies of OCP/HA transformation and OCP in bone minerals
报告人：Prof. Yang Leng
Department of Mechanical Engineering
Hong Kong University of Science and Technology
This seminar will report two subjects of studies at the speaker’s group: observations of In situ transformation of OCP to HA, and findings of OCP in bone minerals. The transformation of synthetic octacalcium phosphate (OCP) to hydroxyapatite (HA) was induced by electron beam irradiation in TEM. The transformation process and crystalline structure changes were examined via bright field images, selected area diffraction (SAD), high resolution microscopy (HRTEM) and the fast Fourier transformation pattern of HRTEM images. The examinations revealed a mechanism of solid-state OCP/HA transformation. In the solid-state transformation, the OCP/HA crystallographic orientation relation differed from that of Brown’s model. A new geometrical model was proposed based the In situ TEM observations. A TEM study of bone minerals was also found direct evidence that OCP exists in human bone. The bone minerals were extracted from matured human cortical bone in ethylenediamine tetraacetic acid (EDTA) solution at ambient temperature. The OCP was identified by SAD and HRTEM images. The diffraction patterns and HRTEM images of OCP and apatite phases in bone minerals were further compared with those of synthetic OCP and HA crystals. The results show that the OCP/apatite orientation relation in bone minerals is identical to that discovered in solid-state transformation of synthetic OCP to HA.
时间：2008年9月4日（星期四）
上午9：30
地点：4号楼14楼第一会议室
联系人：常江
Tel: 52412804
