Effect of doping different Si source on Ca-P bioceramic coating fabricated by laser cladding

The doping of silicon (Si) has been proved to improve the bioactivity of Ca-P ceramics. In light of this thinking, in the present study, Ca-P coatings with La2O3 by addition of 10 wt% SiO2 and 10 wt% diatomaceous earth (DE) were fabricated by laser cladding on Ti6Al4V, respectively. Coating doped without Si was also fabricated as the comparison group for the experiment. The effect of two different Si sources on the surface morphology, microstructure, microhardness, and bioactivity was systematically studied. The experimental results show that the Si-doped coating is of rough surface morphology, and the addition of DE significantly reduces the number of cracks and improves the microhardness. The X-ray diffraction results reveal that the amount of bioactive phase tricalcium-phosphate (TCP) and hydroxyapatite (HA) reaches maximum in the DE-doped coating. After soaking in simulated body fluid (SBF), the precipitate of bone-like apatite in the DE-doped coating is significantly higher than that of the other coatings.

The Effect of Mixing Method on Preparing Chitosan-Zeolite-Fe Composites on Fe(III) Release

<p>Preparation of an Fe(III) slow-release materials using chitosan and zeolite and evaluation of their release behavior in the 0.33 M citric acid has been done. The composite synthesis was carried out by varying the method of mixing basic ingredients. The first method was done by mixing chitosan gel, zeolite and Fe solution altogether (composite A). The second method was done by mixing chitosan gel with Fe solution and stirring, after that adding zeolite (composite B). The last method was done by interacting zeolite with Fe solution then stirring and then adding chitosan gel (composite C). The structure of the composite was characterized using an infrared spectrophotometer (FTIR), X-Ray diffractometer (XRD), and SEM. Evaluation of release in the citric acid 0.33 M for composite showed that the order of release of Fe(III) from the fastest was chitosan-Fe, composite A, composite B, composite C, zeolite-Fe with values of k are 0.049 mg/g; 0.016 mg/g; 0.015 mg/g; 0.011 mg/g; and 0.006 mg/g, respectively. The SEM images of composite showed rough surface morphology of composites due to the presence of zeolite-Fe which was not coated by the chitosan framework. Thus, it can be concluded that the chitosan-zeolite-Fe composite can be used as a Fe(III) slow-release composite but the variation of mixing method of the materials does no effect on the Fe(III) slow-release properties.</p>

Molecular dynamics simulation of surface morphology during homoepitaxial growth of Copper

In this paper, molecular dynamics (MD) simulation of surface morphology during homoepitaxial growth of Copper was investigated. For this purpose, simulations of Cu deposition on the Cu(111) substrate with an incidence energy of 0.06 eV at 300K were performed using the embedded-atom method (EAM). The grown thin film on Cu(111) reveled a rough surface morphology. During deposition, the important fraction of atoms intended for the upper layers undergone a rising rate of about 40% starting from the 2nd period and continued to increase until 65%, while the lower level reached a permanent rate of only 25% by the 4th period. Otherwise, except at the first layer level, the lower layers are incomplete. This void in the lower layers has favored the growth of the upper layers until a rate of 143% and has accelerated their time appearance. Th incidence energy has favored the filling of lower layers by reducing this surface roughness. However, the temperature effect needs more relaxation time to fill the lower layers.

Microcapsule Particle Size and Size Distribution and its Influencing Factors

The paper studied the microcapsule particle size, size distribution and its influencing factors with melamine formaldehyde resin (MF-resin) as wall and CVL as core. The results indicated that the microcapsules mean particle size decreased, size distribution became narrow with the increase of emulsifying time and shear rate. Low pH value would make the microcapsules have rough surface morphology and large particle size.