Navegando por Autor "Carriço, Artur Silva"
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Artigo Synthesis and characterization of xylan-coated magnetite microparticles(International Journal of Pharmaceutics, 2006-10-13) Araújo, Jose Humberto de; Silva, Amanda Karina Andriola; Silva, Érica L. da; Oliveira, Elquio Eleamen; Soares, Luiz Alberto Lira; Nagashima Junior, Toshiyuiky; Medeiros, Aldo C.; Araújo, Ivonete Batista de; Carriço, Artur Silva; Egito, Eryvaldo Sócrates Tabosa doThis work evaluates an experimental set-up to coat superparamagnetic particles in order to protect them from gastric dissolution. First, magnetic particles were produced by coprecipitation of iron salts in alkaline medium. Afterwards, an emulsification/cross-linking reaction was carried out in order to produce magnetic polymeric particles. The sample characterization was performed by X-ray powder diffraction, laser scattering particle size analysis, optical microscopy, thermogravimetric analysis and vibrating sample magnetometry. In vitro dissolution tests at gastric pH were evaluated for both magnetic particles and magnetic polymeric particles. The characterization data have demonstrated the feasibility of the presented method to coat, and protect magnetite particles from gastric dissolution. Such systems may be very promising for oral administrationArtigo Synthesis of stoichiometric Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing(Elsevier, 2016-05-01) Amorim, Bruno Ferreira; Morales, Marco Antonio Morales; Bohn, Felipe; Carriço, Artur Silva; Medeiros, Suzana Nóbrega de; Dantas, Ana L.We report the synthesis of Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing from α-Fe2O3 and CaCO3. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca2Fe2O5. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe3+ in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700–1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca2Fe2O5 nanoparticles