http://repositorio.ufc.br/handle/riufc/16298 2026-04-20T03:28:51Z http://repositorio.ufc.br/handle/riufc/45369 Título: Caracterização física, química e mineralógica de uma amostra de minério de ferro de brucutu Autor(es): Rocha, Geriane Macedo; Gonçalves, Gisele Maria Campos; Ramos, Kennedy da Silva; Cota, Tiany Guedes; Lima, Rosa Malena Fernandes Abstract: The characterization of an ore allows the predictability of its behavior in relation to the concentration methods. Only size and chemical analyses are not always sufficient, and the recognition of mineral species, their proportions, grain form, and liberability are also fundamental. In this work the physical, chemical and mineralogical characteristics of an iron ore from Brucutu mine in Quadrilátero Ferrífero is presented. Particle size analyses were carried out by sieve and laser granulometer, chemistry by X-ray fluorescence and mineralogical by optical microscopy and X-ray diffraction. Based on the results obtained, the ore was classified as friable, with an overall Fe content of 42.9% and SiO2 of 36.1%. The iron minerals identified were hematite and goethite, and the main gangue mineral was quartz. In the fraction +1.0 mm the quartz occurs mainly in mixed particles with the hematite and goethite grains. Below this size, the same occurs as free particles. Above 0.15 mm the hematite is predominantly porous, and below 0.15 mm granular. Goethite is associated with granular hematite in all size distribution.Keywords: Characterization; Iron ore; Mineral processing. Tipo: Artigo de Periódico 2019-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/45358 Título: Monitoramento de impedância elétrica de desdobramento de proteínas Autor(es): Lima, Sandro V.; Oliveira, Helinando; Melo, Celso Abstract: We have applied electrical impedance spectroscopy (EIS) to investigate how the dielectric characteristics of protein aqueous solutions respond to varying amounts of a co-dissolved surfactant. Using bovine serum albumin (BSA) as our model system, we followed the conformational changes of the protein molecules that result from the progressive increment in the concentration of either ionic (sodium dodecyl sulfate – SDS, and dodecyltrimethylammonium bromide – DTAB) or non-ionic (Triton X-100) surfactants, and modeled the corresponding electrical response through a modified Randles circuit. From the dielectric data, we selected the behavior of the passive layer resistance (RPL) as a convenient parameter to map the conformational changes in the BSA molecules. The profile of the dielectric response of the BSA–surfactant solutions as a function of the amount of the added surfactant allows the identification of different ranges of the detergent relative concentration that can be associated to each one of the successive regimes of the surfactant–protein interaction. These results were similar to those obtained from a standard Stern–Volmer analysis of the fluorescence emission of the protein chain, with a better agreement occurring in the case of the non-ionic surfactant. We propose this novel EIS approach as a convenient alternative methodology to follow conformational changes of weakly fluorescent proteins. Tipo: Artigo de Periódico 2016-11-07T00:00:00Z