Papers by Author: Guang Fu Yin

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Authors: Jun Cui, Jun Ou, Yong Lie Chao, Q.P. Gao, Guang Fu Yin, H. Wang, J.F. Shen, Yang Xi Chen
Abstract: Dental ceramic materials do not always show linear expansion behavior. In general, thermal contraction behavior of dental porcelain can be described with the polynomial function: L/L= C+α1 T+α2 T2. In addition, a new method for taking into consideration of nonlinear contraction behavior of dental ceramics is proposed for calculating thermal mismatch value (α) between substrate and veneering materials. Discs of eight substrate/veneer combinations (n=10) were fabricated for thermal shock testing. In this study, a stepwise multiple regression analysis was performed to determine the relationship between thermal shock test results and thermal mismatch value (α) on these combinations. A high degree of correlation was found between αs-b and T. The new method proves to be a reliable one to predict thermal compatibility of multi-layer dental ceramic composites.
Authors: Yun Qing Kang, Guang Fu Yin, Ke Feng Wang, Lin Luo, Li Liao, Ya Dong Yao
Abstract: The ability of apatite to form on the surface of biomaterials in simulated body fluid (SBF) has been widely used to predict the bone-bonding ability of bioceramic and bioceramic/polymer composites in vivo. Porous β-tricalcium phosphate/poly(L-lactic acid) (β-TCP/PLLA) composite scaffold was synthesized by new method. The ability of inducing calcium phosphate (Ca-P) formation was compared in static simulated body fluid(sSBF) and dynamic simulated body fluid (dSBF). The Ca-P morphology and crystal structures were identified using SEM, X-ray diffraction and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the typical features of bone-like apatite formation on the surface and the inner pore wall of β-TCP/PLLA. Ca-P formation on scaffold surfaces in dSBF occurred slower than in sSBF and was more difficult with increasing flow rate of dSBF. The ability of apatite to form on β-TCP/PLLA was enhanced by effect of each other that has different degradable mechanism. Porous β-TCP/PLLA composite scaffold indicates good ability of Ca-P formation in vitro.
Authors: B.G. Li, Yun Qing Kang, Guang Fu Yin, Chang Qiong Zheng
Abstract: In this paper, the adsorption of human serum albumin (HSA), human serum fibrinogen (HFG) and human serum immune globulin (IG) on surfaces of diamond like carbon film (DLC), diamond film (DF) and graphite has been studied. The adsorption isotherms of single component protein solution and the competitive adsorption of binary system have been investigated by radioisotope 125 I labeling method. Results showed that (1) the adsorptive amounts of HSA on DLC is more than that of HFG, but the adsorptive amounts of HFG on DF and graphite are apparently more than those HSA; (2) the relative competitive adsorption ability of three proteins on DF and graphite surfaces is HFG > IG > HSA, but that on DLC is HFG ≈ HAS > IG, comparison with HSA, there is no apparent competitive adsorption superiority on DLC for HFG. These results indicated that there is no apparent distinction for the adsorption of three human serum proteins on DLC, but the adsorption of HFG on DF and graphite takes precedence in varying degrees. It probably makes rational explanation for the result of blood-compatibility tests in vitro that DLC is good, but DF and graphite are worse.
Authors: Bin Xiao, Wei Zhong Yang, Da Li Zhou, Guang Fu Yin, Huai Qing Chen
Abstract: Bioactive composite of apatite-wollastonite(AW)/β-tricalcium phosphate (β-TCP) was prepared. The nucleation and growth of bio-apatite on the surface of AW/β-TCP ceramic in simulated body fluid (SBF) were investigated. The surface morphological structure, phase compositions and microstructure of the materials were characterized by scan electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (IR); Results show that the surfaces of the AW/β-TCP composite ceramic are covered with a layer of carbonate hydroxyapatite (HCA) when soaked in SBF, which indicates their bioactivity; Such HCA layer is composed of fine ball-like HA granules. With excellent bioactivity and bio-absorption, AW/β-TCP bioactive composite ceramic is expected to be a good candidate for bone substitutes and bone tissue engineering scaffolds.
Authors: Yun Qing Kang, Guang Fu Yin, Ke Feng Wang, Lin Luo, Ya Dong Yao
Abstract: Poly-L-lactide/β-tricalcium phosphate (PLLA/β-TCP) porous scaffold fabricated by freeze shrinking/particulate leaching was studied. The scaffold was immersed into simulated body fluid (SBF) for 1, 2, 3 and 4 weeks and analyzed by the SEM, XRD and FT-IR spectroscopy. The ability of inducing Ca-P formation was compared among the scaffolds with different content of β- TCP. SEM shows a typical feature of apatite precipitation. Diffraction peak of new crystal structure was detected by x-ray diffraction (XRD). IR Spectrum in which absorption bands arise from newly formed groups of carbonate apatite can be seen. At the same testing point, higher density of Ca-P crystal can be observed by SEM in scaffold with high content of β-TCP than in low group. Until 3 weeks, Ca-P individual crystal started on the wall of inner pore of pure PLLA. Porous PLLA/β-TCP composite scaffolds also indicate good ability of Ca-P formation in vitro, the ability of which to form apatite was enhanced by addition of each other that has different degradable mechanism.
Authors: Xi Ming Pu, Yun Qing Kang, Ai Zheng Chen, Li Liao, Guang Fu Yin
Abstract: 5-Fluorouracil-poly(L-lactide) (5-Fu-PLLA) microspheres have been co-precipitated in a process namely solution-enhanced dispersion by supercritical CO2 (SEDS). First, the 5-Fu is successfully micronized and then used to produce the 5-Fu-PLLA microspheres. The 5-Fu-PLLA microspheres synthesized in the SEDS process exhibited a rather spherical shape, smooth surface, and a narrow particle size distribution, where it ranged from 531 nm to 1280 nm, with a mean particle size of 793 nm. The dichloromethane residue in the 5-Fu-PLLA microspheres is 46 ppm. The average drug load of the 5-Fu-PLLA microspheres is 12.7%. The results of this study indicate that the SEDS process is an effective technique to co-precipitate 5-Fu and PLLA as composite microspheres.
Authors: Yun Zhang, Guang Fu Yin, Yue Hua Wang, Wei Zhong Yang, Yun Qing Kang
Abstract: Degradation of surface modified β-tricalcium phosphate (β-TCP) and poly L lactic acid (PLLA) composite scaffolds were investigated in vitro. Bending and compressive strengths were tested by electromechanical universal material testing machine. Molecular weight changes of lactic acid during degradation were measured by gel permeation chromatography (GPC). Phase composition of the surface after soaking was analyzed by Fourier transform infrared ray (FTIR). The surface and cross section of scaffold samples after degradation were observed by Scanning electron microscope (SEM).The results show that degradation speed can be controlled by adjusting the ratio of β-TCP to PLLA in the composite. PLLA can compound more closely with surface modified β-TCP than with non-modified one. The final compressive strength and bending strength of the scaffolds reach 7.11MPa and 2.20MPa respectively, which satisfies the need for bone tissue engineering scaffolds in clinic applications.
Authors: Ya Dong Yao, Guang Fu Yin, Xiao Wei Cheng, Xiang Li Gou
Abstract: Silicate fireproof coatings for tunnels (FCT) have many eminent properties. But low adhesion strength and poor water/fire-resistance of this kind of materials largely limit its applications. Here we reported a new kind of FCT based on high alumina cement as principle adhesive, redispersible powder as assisting adhesive, ammonium polyphosphate as fire-retardant material, vermiculite as adiabatic padding, and magnesium hydroxide as assisting reagents. The influence of various experimental conditions on fire resistance, adhesion strength and water resistance were carefully studied. Results showed that dispersible emulsoid powder was a key component affecting adhesion strength and water resistance of FCT, whereas fire-retardant material posed significant effects on the fire resistance.
Authors: Yun Qing Kang, Guang Fu Yin, Lin Luo, Ke Feng Wang, Yu Zhang
Abstract: In bone tissue engineering, porous scaffolds served as the temporary matrix are often subjected to mechanical stress when implanted in the body. Based on this fact, the goal of this study was to examine the effects of mechanical loading on the in vitro degradation characteristics and kinetics of porous scaffolds in a custom-designed loading system. Porous Poly(L-lactic acid)/β-Tricalcium Phosphate (PLLA/β-TCP) composite scaffolds fabricated by using solution casting/compression molding/particulate leaching technique (SCP) were subjected to degradation in simulated body fluid (SBF) at 37°C for up to 6 weeks under the conditions: with and without static compressive loading, respectively. The results indicated that the increase of the porosity and decrease of the compressive strength under static compressive loading were slower than that of non-loading case, and so did the mass loss rate. It might be due to that the loading retarded the penetration, absorption and transfer of simulated body fluid. These data provide an important step towards understanding mechanical loading factors contributing to degradation.
Authors: Jiang Li Lin, Ke Cai, Yuan Wen Zou, Li Gou, Jun Guo Ran, Guang Fu Yin
Abstract: Hemocompatibility of a biomaterial is determined by the interactions between its surface and blood. Due to the complicated action mechanism, various effective ways and the multiple affective factors of the hemocompatibility, a comprehensive evaluation needs to be built instead of single index. Therefore, the platelet consumption ratio of 10 kinds of biomaterials including Ti6Al4V-TiC-DLC gradient coat material was studied based on image analysis method. Combined with the kinetic clotting time and the hemolysis ratio, the comprehensive hemocompatibility evaluation of the material is carried out based on the improved principal component analysis. First, linear transformation of negative index is carried out. Second, index is under a dimensionless using the logarithmic treatment, then to acquire all variants’ principal component and their characteristic vectors. Finally, comprehensive evaluation index of hemocompatibility is constructed. The improved principal component analysis avoids the effect of correlativity among indexes during anaphase evaluation, and can more correctly maintain the original information of indexes. Thus, the research provides a new idea to the comprehensive evaluation of Hemocompatibility.
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