Bioceramic composites were synthesized by sintering the powders of hydroxyapatite (HAp) mixed directly with additive of 0.5, 1.0, 2.0, 5.0 and 10 wt.%SiO(2), respectively, at 1,200( composite function)C. X-ray diffraction (XRD) analysis indicated that the phase transformation from HAp to tricalcium phosphate (TCP) comprising alpha-TCP and Si-TCP occurred and became more prominent with the addition of SiO(2) and the increase in SiO(2) content. The observations of their surface microstructures showed that the addition of SiO(2) suppressed the grain growth and promoted the formation of crystalline-glassy composites denoted HAp + TCP/Bioglass. As the SiO(2) content is as high as 5 wt.%, the composite made a feature of crystalline clusters with different sizes consisting of HAp and TCP grains surrounded by the matrix of glassy phase. Furthermore, the dependence of in vitro bioactivity of these composites on the SiO(2) content was biomimetically assessed by determining the changes in surface morphology, i.e., bone-like apatite layer growth, after soaking in an acellular stimulated body fluid (SBF) for 3 days at 36.5( composite function)C. It was found that the HAp-SiO(2) composites showed a much faster bone-like layer growth than pure HAp, and the propensity of composites to exhibit a better bioactivity was getting more notable with increasing SiO(2) content, except for the case of the highest content of 10 wt.%. It was believed that the formation of the bone-like layer on the surfaces of these bio-composites is closely related to the increasingly provided silanol groups and transformed TCP phase in materials associated with the content of SiO(2) added.
Five Chinese species of Epimedium (Berberidaceae), E. simplicifolium T. are the only species of the genus previously described with unifoliolate leaves. Here, the authors review these five species based on extensive examination of specimens in herbaria and careful observation in the field and garden. E. simplicifolium is treated as a synonym of E. acuminatum Franch., and with the exception of E. elachyphyllum, the taxa are found to have predominantly trifoliolate and only occasionally unifoliolate leaves. Neotypes for E. zhushanense and E. glandulosopilosum are designated. In addition, we describe some characters of E. baojingensis, E. zhushanense, E. glandulosopilosum and E. elachyphyllum.
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