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CONTENTS
Volume 4, Number 4, December 2015
 

Abstract
Contamination by bacterial strands is a major problem after bone replacement surgeries, so there is a great need to develop low cost biocompatible antibacterial bioactive scaffolds to be used in bone tissue engineering. For this purpose, nano-zinc doped hydroxyapatite with different zinc-concentrations (5, 10 and 15 mol%) was successfully prepared by the wet chemical precipitation method. The prepared powders were used to form porous scaffolds containing biodegradable Ca-cross-linked alginate (5%) in order to enhance the properties of alginate scaffolds. The scaffolds were prepared using the freeze-gelation method. The prepared powders were tested by X-ray diffraction; transmission electron microscope and Fourier transform infrared analyses, while the prepared scaffolds were investigated by Fourier transform infrared analyses, thermogravimetric analyses and measurement of the antibacterial properties. Best results were obtained from scaffold containing 15% mol zinc-doped hydroxyapatite powders and 5% alginate concentration with ratio of 70:30.

Key Words
bioceramics; nano-zinc doped hydroxyapatite; scaffolds; nanostructure; antimicrobial activity

Address
Basma E. Abdel-Ghany, Bothaina M. Abdel-Hady, Abeer M. El-Kady,Hanan H. Beheiry: Biomaterials Department, Advanced Materials and Nanotechnology Lab,National Research Centre, Giza, Egypt
Osiris W. Guirguis: Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt

Abstract
It has been reported in the technical literature that orotic acid can be used in order to induce improved crystallization of biodegradable and biocompatible polymers like poly(L-lactic acid), polyhydroxybutyrate and poly(hydroxybutyrate-co-hydroxyhexaonat). The expected advantage of the changed crystalline structure is a reinforcing effect of the polymers. A lot of papers reported about the application of inorganic and organic agents for acceleration of heterogeneous nucleation. This study reports on an attempt to use orotic acid as appropriate non-toxic nucleating agent for improving mechanical properties of isotactic polypropylene. Special attention is given to demonstrate the effect of nucleation in a typical melt spinning process in order to improve the mechanical properties. The effects were demonstrated using rheology, thermal analysis and tensile testing.

Key Words
polypropylene; orotic acid; nucleation; fiber; mechanical properties

Address
Roland Vogel, Harald Brünig and Liane Häussler: Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Hohe Stra

Abstract
Experiment on roughness and micro pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The relation between roughness and glossiness with reduction in height, roll surface roughness, emulsion parameters was analyzed. The surface morphology of micro pit defects was observed by SEM, and the effects of micro pit defects on rolling reduction, roll surface roughness, emulsion parameters, lubrication oil in deformation zone and work roll diameter were discussed. With the increasing of reduction ratio strip surface roughness Ra(s), Rp(s) and Rv(s) were decreasing along rolling and width direction, the drop value in rolling direction was faster than that in width direction. The roughness and glossiness were obtained under emulsion concentration 3% and 6%, temperature 55

Key Words
stainless steel; cold rolling; lubrication; roughness; micro pit defects

Address
Changsheng Li and Tao Zhu: State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China
Bo Fu and Youyuan Li: Baosteel Stainless Steel Co. Ltd, Shanghai, 200431, China

Abstract
We present a method, supported by theoretical analysis, for optimizing the usage of the critical rare earth element dysprosium in Nd2Fe14B (NdFeB)-based permanent magnets. In this method, we use Dy selectively in locations such as magnet edges and faces, where demagnetization factors are largest, rather than uniformly throughout the bulk sample. A 200 nm thick Dy film was sputtered onto a commercial N-38, NdFeB magnets with a thickness of 3 mm and post-annealed at temperatures from 600-700

Key Words
NdFeB magnets; sputter deposition; selective Dy diffusion; magnetic properties; theoretical analysis

Address
Huseyin Ucar, David S. Parker and M. Parans Paranthaman: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

I.C. Nlebedim, R.W. McCallum: Ames Laboratory, Ames, Iowa 50011, USA

S.K. McCall: Lawrence Livermore National Laboratory, Livermore, California 94550, USA



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