Papers by Author: Qi Yi Zhang

Abstract: The fluorescence and up-conversion spectral properties of Er3+-doped TeO2-ZnO and TeO2-ZnO-PbCl2 glasses suitable for developing optical fiber amplifier and laser have been fabricate and characterized. Strong green (around 527-550 nm) and red (around 661 nm) up-conversion emissions under 977 nm laser diode excitation were investigated, corresponding to 2H11/2, 4S3/2, ® 4I15/2 and 4F9/2 ® 4I15/2 transitions of Er3+ ions respectively, have beenobserved and the involved mechanisms have been explained. The dependence of up-converted fluorescence intensity versus laser power confirm that two-photons contribute to up-conversion of the green-red emissions. The novelty of this kind of optical material has been its ability in resisting devitrification, and its promising optical properties strongly encourage for their further development as the rare-earth doped optical fiber amplifiers and upconversion fiber laser systems.

Abstract: The electrochemical cathode bioactivating titanium with additive of citrate was reported. After the treatment, there was a uniform dense layer with very tiny granules on the surface of the titanium, this layer was composed of amorphous calcium phosphate-citrate (ACP-CIT) with a thickness of about 150nm. After immersion in saturated calcium phosphate solution, the morphology at different time points of the early stage was quite different. The changes of morphology showed that the citrate in amorphous calcium phosphate modulated the crystal growth.

Abstract: In vitro method has often been used in the biodegradation/bioactivity evaluation of bioactive ceramics for its convenience and saving in time and outlay. The simulated body fluid (SBF) suggested by Kokubo was a good simulation of the osteoproduction environment in osseous tissue and has been proved to be a good method to study the bioactivity of biomaterials and the mechanism of bone bonding. But SBF is not a suitable method to research the osteoinduction of biomaterials. The results from SBF were not consistent with that from in vivo in muscle. The local ion concentration is the key factors to affect the nucleation and growth of apatite. In muscle the effect of body fluid flowing on local ion concentration cannot be ignored. A dynamic SBF suggested by these authors of this paper not only simulated the ion concentration of body fluid, but also simulated the effect of body fluid flowing on the local ion concentration near the surface or in biomaterials in muscle. The results from the dynamic SBF were in good agreement with that of the implantation experiments in muscle. The results from dynamic SBF showed that apatite only formed on the walls of macropores of the porous CaP, no apatite formed on the surface of both dense and porous CaP. The new bone only formed on the walls of macropores of porous CaP implanted in muscles, no apatite or osseous tissue could be found on the surfaces of both porous and dense CaP. The dynamic SBF preferably simulated the osteoinduction environment in non-osseous tissue and can be used in osteoinductivity evaluation of bioceramics.