Navegando por Autor "Oliveira, Michelle de"

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Comparison between hydroxyapatite/soapstone and hydroxyapatite/ reduced graphene oxide composite coatings : synthesis and property improvement.
(2021) Nicomedes, Daniel Nilson Nunes; Mota, Laureana Moreira; Vasconcellos, Rebecca; Medrado, Nathanael Vieira; Oliveira, Michelle de; Alvarenga, Érika Lorena Fonseca Costa de; Juste, Karyne Ramos de Campos; Righi, Ariete; Manhabosco, Sara Matte; Silva, Guilherme Jorge Brigolini; Araújo, Fernando Gabriel da Silva; Oliveira, Alan Barros de; Batista, Ronaldo Junio Campos; Soares, Jaqueline dos Santos; Manhabosco, Taíse Matte
Economic viability and eco-friendliness are important characteristics that make implants available to the pop- ulation in a sustainable way. In this work, we evaluate the performance of a low-cost, widely available, and eco- friendly material (talc from soapstone) relative to reduced graphene oxide as reinforcement to brittle hy- droxyapatite coatings. We employ a low-cost and straightforward technique, electrodeposition, to deposit the composite coatings on the titanium substrate. Corrosion, wear, and biocompatibility tests indicate that the reduced graphene oxide can be effectively replaced by talc without reducing the mechanical, anticorrosion, and biocompatible composite coatings properties. Our results indicate that talc from soapstone is a promising ma- terial for biomedical applications.
Growth and characterization of ammonium nickel-cobalt sulfate Tutton’s salt for UV light applications.
(2018) Ghosh, Santunu; Oliveira, Michelle de; Pacheco, Tiago de Sousa; Perpétuo, Genivaldo Julio; Franco, Carlos Joel
We have obtained a set of sample crystals of the family of Tutton’s salt comprise in the isomorphic series with general chemical formula (NH4)2NixCo(1−x) (SO4)2·6H2O, by employing growth from solutions by slow evaporation technique. The samples crystals were characterized by ICP-AES, X-ray powder diffraction analysis, thermogravimetric analysis, UV–Vis-NIR, Raman and FTIR spectroscopy. This type of material has been studied because of its physical and chemical properties not yet understood and they have potential technological applications. Chemical analysis of the samples by ICP-AES method allowed us to investigate the efficiency of the method of growth used. Thermogravimetric analysis provides the information about the thermal stability of the obtained crystals for high temperature applications, and powder X-ray diffraction analysis at ambient and high temperature reveals the structural quality and structural change of the samples respectively. We have used Raman spectroscopy in the range 100–4000 cm−1 and FTIR spectroscopy in the range 400–4000 cm−1 to understand the internal vibrational mode of the octahedral complexes [Ni(H2O)6]2+ and [Co(H2O)6]2+, SO42− and NH4+ tetrahedra. The transmittance of our mixed ammonium nickel cobalt sulfate hexahydrate (ACNSH) crystals is 75% in the UV region, which indicates that they are ideal to use in UV light filters and UV sensors.
Growth and characterization of potassium cobalt nickel sulfate hexahydrate crystals : a new UV light filter.
(2017) Pacheco, Tiago de Sousa; Ghosh, Santunu; Oliveira, Michelle de; Barbosa, Ananias Alves; Perpétuo, Genivaldo Julio; Franco, Carlos Joel
Samples of the empirical formula Kþ 2 Ni2þ x Co2þ ð1 xÞ ðSO4Þ 2,6H2O were grown with a partial occupation of the cations Co and Ni. Mixed crystals with good optical quality were obtained by the slow evaporation growth method. In the decomposition process, these crystals suffer a mass loss of approximately 24%, equivalent to water molecules forming octahedral coordination ions of Ni and Co. The optical characteristics of the grown crystals were measured where transmittance reached more than 80% in the wavelength range of 190e390 nm. By Raman spectroscopy, the vibrational modes of SO2 4 , H2O and of the octahedral Ni(H2O)6 and Co(H2O)6 were identified.
Growth and structural analysis of ammonium nickel cobalt sulfate hexahydrate crystals.
(2017) Oliveira, Michelle de; Ghosh, Santunu; Pacheco, Tiago de Sousa; Perpétuo, Genivaldo Julio; Franco, Carlos Joel
We have obtained a set of crystals of the empirical formula (NH4)2NixCo(1−x)(SO4)2 · 6H2O with the different concentrations of Ni and Co, by employing the growth from the solution technique. We have chosen the monocrystal (NH4)2Ni0.3Co0.7(SO4)2 · 6H2O for the structural analysis. The structure was resolved by x-ray diffraction method and refined by the full-matrix least-squares method with the help of SHELXS software. This crystal belongs to a monoclinic space group P21/c with crystal parameters, a = 6.2455 (2) Å, b = 12.5065 (3) Å, c = 9.2303 (2) Å, α = γ = 90°, β = 106.995 (3)°, V = 689.49 (3) Å3, Z = 2. We have shown the configuration of the unit cell of the above monocrystal, along with that we have also reported the length, angles between the bonds and the geometry of the hydrogen bonds of the monocrystal.