The main objective of this study was to synthesize hydroxyapatite-ciprofloxacin composites using a chemical precipitation method and to evaluate the properties and in vitro release profile of the drug from the hydroxyapatite-ciprofloxacin composites. Composite characterization was achieved by FT-IR, XRD and DLS. Ciprofloxacin determination was accomplished by HPLC, resulting in good incorporation efficiency of the drug (18.13 %). The in vitro release study (Higuchi model C = K t1/2 and Ritger-Peppas model, C = K t0.6) showed a diffusion-controlled mechanism. The antibacterial activity showed that the bacterial growth inhibition zones were approximately equal for the synthesis composites and for the mechanical mixture on the Staphylococcus aureus germ. The use of hydroxyapatite, which is a biocompatible, bioactive and osteoconductive material, with ciprofloxacin, which has good antibacterial activity in this composite, makes it suitable for the development of bone grafts. Furthermore, the synthesis process allows a slow local release of the drug.

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This paper presents a study about the influence of some alloying elements like Ni and Co on the elaboration of W-Cu electrical contacts. For the experimental work four types of mixture were prepared using mechanical alloying (MA) technique for six hours. All the samples had the same Ni and Co content (2%) varying the W content as following: 88W-10Cu-Ni, 78W-20Cu-Ni, 68W-30Cu-Ni, 88W-10Cu-Co, 78W-20Cu-Co and 68W-30Cu-Co. The mixtures were pressed in a cylindrical die with 10 mm diameter at two pressures: 400MPa and 600 MPa. The sintering process was carried out in an electrical furnace at the 1180 OC and maintained at this temperature for three hours. For all the samples the electrical properties: resistivity, conductivity, resistance were measured and were made correlation between electrical contacts with Ni and the other with Co. It is observed that, the compaction pressure influence the electrical properties and better properties are obtained for the samples compacted at 600 MPa.

Gold nanoparticles are considered the newest drug carriers for different diseases. Therefore it is appropriate continuous optimization of their preparation. In this study, gold colloids with an average size of 1 -26 nm were obtained by the reduction of tetrachloroauric acid with trisodium citrate. The nanomaterials were characterized by UV-Vis spectroscopy and dynamic light scattering technique. In addition, zeta potential was measured for samples synthesized in order to determine the stability of the colloids. A Two-level Full Factorial design was chosen to determine the optimum set of process parameters (chloroauric acid concentration and sodium citrate concentration) and their effect on various gold nanoparticles characteristics (size and zeta potential). These effects were quantified using Design of Experiments (DoE) with 5 runs and 1 centerpoint. The selected objective and process model in this investigation are screening and interaction. Findings from this research show that to obtain particles larger than 35 nm, it is recommended to increase sodium citrate concentration, at low chloroauric acid values. These conditions will help to achieve smaller zeta potential, too.