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Wu Y.,Tongling University | Song M.,Tongling University | Wang C.,Anhui Traditional Chinese Medical College
The Scientific World Journal | Year: 2014

The authors first present a Rosenthal inequality for sequence of extended negatively dependent (END) random variables. By means of the Rosenthal inequality, the authors obtain some complete moment convergence and mean convergence results for arrays of rowwise END random variables. The results in this paper extend and improve the corresponding theorems by Hu and Taylor (1997). © 2014 Yongfeng Wu et al. Source

Zhang C.Y.,CAS Hefei Institutes of Physical Science | Chen J.,Anhui Traditional Chinese Medical College | Zhuang Z.,CAS Hefei Institutes of Physical Science | Zhang T.,CAS Hefei Institutes of Physical Science | And 2 more authors.
Journal of Applied Polymer Science | Year: 2012

Nano-fibrous hydroxyapatite/chitosan (HA/CS) composites with HA contents of 0-70 wt % were prepared by in situ hybridization with a preprepared chitosan film as semipermeable membrane to slow down the hybridization process. The phase composition, microstructure, and morphology of the composites were characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy. It was found that the in situ prepared inorganic phase was hydroxyapatite nano-fibers that were uniformly dispersed in the chitosan matrix. The average diameter of the fibers were about 3 nm, while the length of the fibers increases from 20 to 60 nm when the hydroxyapatite content increased from 10 to 70 wt %. The compressive strength and Young's modulus of these nano-fibrous HA/CS composites increased with the increasing HA content and reached the highest values of 170 and 1.7 GPa, respectively, at the HA content of 50-70 wt %, which were much higher than the values of samples prepared by coprecipitation. © 2011 Wiley Periodicals, Inc. Source

Zhang C.,Anhui Traditional Chinese Medical College
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2012

The aim of this research was to estimate the bioactivity of nano-hydroxyapatite/poly (L-lactic acid) composites in simulated body fluid. In vitro test showed that the pH value of simulated body fluid (SBF) declined gradually and the existence of hydroxyapatite (HA) particles neutralized the acid degradation product of poly (L-lactic acid) (PLLA). Bone-like apatite deposited on the surface, and silkworm-like crystals and plate-like clusters appeared after soaking. At the same time, there were many honeycomb-like pores caused by nano-composite degraded. The results indicated that the hydroxyapatite/poly (L-lactic acid) nano-composites have good bioactivity and degradation characteristics. Source

Zhang C.Y.,CAS Hefei Institutes of Physical Science | Zhang C.Y.,Anhui Traditional Chinese Medical College | Lu H.,CAS Hefei Institutes of Physical Science | Zhuang Z.,CAS Hefei Institutes of Physical Science | And 2 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2010

Nano-hydroxyapatite/poly(L-lactic acid) (nano- HA/PLLA) composites with uniform HA distribution and good mechanical performance were fabricated by a modified in situ precipitation method, using Ca(OH)2 and H 3PO4 as precursors for the synthesis of HA phase. This method has solved the aggregation problem of the nano-sized particles in the polymer matrix. The X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy were used to characterize the phase composition, chemical interactions and morphology of the composites, while the mechanical properties were determined by compressive measurements. The results show that the rod-like nano-HA particles synthesized by this method were uniformly distributed in the PLLA matrix. The compressive strength and Young's modulus of the composites were greatly enhanced and reached the values of 155 MPa and 3.6 GPa at 20 wt% HA content, respectively, which are much higher than those of the reference samples fabricated by direct mixing of PLLA with nano-HA particles. This supports the potential of these composites for applications in bone tissue engineering and load bearing bone defects repair. © Springer Science+Business Media, LLC 2010. Source

Zhang C.,Anhui Traditional Chinese Medical College | Zhang C.,CAS Hefei Institutes of Physical Science | Peng D.,Anhui Traditional Chinese Medical College | Lu C.,Anhui Traditional Chinese Medical College | And 2 more authors.
Advanced Materials Research | Year: 2012

In this paper the hydroxyapatite fibers reinforced chitosan nanocomposites with high hydroxyapatite dosage (70-90 wt%) were synthesized by in-situ hybridization. The semi-permeable membrane was used to control the process of hybridization and morphology of hydroxyapatite. The compositional and morphological properties of nanocomposites were investigated by FTIR spectroscopy, X-ray diffraction, and transmission electron microscopy. The results showed that the hydroxyapatite were carbonated nanometer crystalline fibers with high aspect ratio (about 25) and dispersed uniformly in the nanocomposites. The high-resolution image indicated that the growth of nano-hydroxyapatite crystallites in the chitosan matrix preferred in the c-axis. The mechanical properties of these nanocomposites were enhanced dramatically and the compressive strength increases almost to 170MPa when the hydroxyapatite content is 70 wt%. The in vitro tests indicated that the composites have high bioactivity and degradation. These properties illustrated the potential application of this kind of nanocomposites for bone tissue engineering. © (2012) Trans Tech Publications. Source

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