Sol-gel synthesis and characterization of Fe(2)O(3) center dot CeO(2) doped with Pr ceramic pigments

Undoped x center dot alpha-Fe(2)O(3) y center dot CeO(2) and doped with praseodymium ceramic pigments were obtained by the sol-gel method after heat treatment at 800 degrees C for 2 h. These pigments were characterized by XRD, nitrogen adsorption, scanning electron microscopy, ultraviolet-visible absorption spectroscopy and colorimetrical measurements. Red and brown colors with several tonalities were observed after changes with Ce and Pr concentration.

Corrosion behavior in graphite refractories impregnated with ZrO 2 and CeO 2 carrying solutions

This paper investigates corrosion behavior in graphite refractory hot metal impregnated with ZrO 2 and CeO 2 carrying solutions used in Blast Furnace hearth, consisting of 50% graphite and 50% anthracite. Corrosions tests were carried out by means of finger test method in an induction furnace, using bar-shaped 30×30×280 mm test specimens and hot metal from CSN#2 Blast Furnace runner. The temperature chosen for this test was 1520°C and sixty-minute isotherm. Upon test completion, test specimens were characterized by their dimensional variation, X-ray diffractometry and Scanning Electronic Microscopy (SEM).

Influence of mineralizer agents on the growth of crystalline CeO 2 nanospheres by the microwave-hydrothermal method

Cystalline ceria (CeO2) nanoparticles have been synthesized by a simple and fast microwave-assisted hydrothermal (MAH) under NaOH, KOH, and NH4OH mineralizers added to a cerium ammonium nitrate aqueous solution. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transformed-IR and Raman spectroscopies. Rietveld refinement reveals a cubic structure with a space group Fm3m while infrared data showed few traces of nitrates. Field emission scanning microcopy (FEG-SEM) revealed a homogeneous size distribution of nanometric CeO2 nanoparticles. The MAH process in KOH and NaOH showed most effective to dehydrate the adsorbed water and decrease the hydrogen bonding effect leaving a weakly agglomerated powder of hydrated ceria. TEM micrographs of CeO2 synthesized under MAH conditions reveal particles well-dispersed and homogeneously distributed. The MAH enabled cerium oxide to be synthesized at 100 °C for 8 min. © 2012 Elsevier B.V. All rights reserved.

Gadolinium-doped cerium oxide nanorods: novel active catalysts for ethanol reforming

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da prática de alimentação infantil e de fatores associados sobre a ocorrência da cárie dental em pré-escolares de 18 a 48 meses

Este estudo foi realizado objetivando estudar o efeito das práticas de alimentação infantil e de fatores associados sobre a ocorrência de cárie dental. Para isso, determinou-se o ceo-d e o ceo-s em 156 crianças de 18 a 48 meses e foi aplicado às mães um questionário incluindo perguntas sobre a ocupação do pai, nível educacional da mãe, higiene bucal, época de erupção do dente e sobre práticas de alimentação infantil. Os dados obtidos foram analisados através dos testes X2 e Mann-Whitney U. A média do ceo-s foi 3,4 com 40% das crianças livres de cáries, sendo que 36 e 24% tinham um ceo-d maior que 0 e 4, respectivamente. Notou-se que 72% das crianças eram alimentadas ao seio, 17% apenas com mamadeira e 10% pelos dois meios. Das crianças alimentadas apenas com mamadeira 70% apresentaram cárie. A cárie de mamadeira foi observada em 20% das crianças, sendo que 77% destas tinham sido alimentadas por mais de 12 meses. As crianças, cujos pais eram profissionais com terceiro grau de escolaridade, tiveram significativamente menos cárie do que aquelas de pais com nível técnico ou pais operários. A prevalência de cárie na faixa etária estudada foi relativamente alta. As crianças com cárie de mamadeira tenderam a manter seus hábitos de aleitamento por mais de 12 meses, sendo que o uso de mamadeira açucarada estava presente em 100% dos casos.

Sistema computacional para índices de cárie dentária: banco de dados e análise estatística

Apresenta-se um sistema computacional, denominado ICADPLUS, desenvolvido para elaboração de banco de dados, tabulação de dados, cálculo do índice CPO e análise estatística para estimação de intervalos de confiança e comparação de resultados de duas populações.Tem como objetivo apresentar método simplificado para atender necessidades de serviços de saúde na área de odontologia processando fichas utilizadas por cirurgiões dentistas em levantamentos epidemiológicos de cárie dentária. A característica principal do sistema é a dispensa de profissional especializado na área de odontologia e computação, exigindo o conhecimento mínimo de digitação por parte do usuário, pois apresenta menus simples e claros como também relatórios padronizados, sem possibilidade de erro. Possui opções para fichas de CPO segundo Klein e Palmer, CPO proposto pela OMS, CPOS segundo Klein, Palmer e Knutson, e ceo. A validação do sistema foi feita por comparação com outros métodos, permitindo recomendar sua adoção.

Densification and electrical conductivity of fast fired manganese-doped ceria ceramics

Reactive pure and manganese-doped (5% and 10 at.%) ceria nanosized powders were prepared by the polymeric precursor technique. Physical properties of powder materials were studied by X-ray diffraction, nitrogen adsorption, and diffuse reflectance infrared Fourier transform spectroscopy. Characterization of powder compacts after fast firing at 1200 degrees C for 5 min was carried out by scanning electron microscopy and impedance spectroscopy measurements. The bulk apparent density of sintered pellets was determined for pellets of different compositions sintered at 1200 degrees C. A gradual decrease of the particle size occurs with increasing doping content. Relatively high values of apparent density were obtained after fast firing doped specimens at 1200 degrees C. DRIFT spectra evidence that a fraction of Mn ions was segregated onto particles surface. The electrical resistivity of sintered pellets reveals different mechanisms of conduction depending on the Mn content. (C) 2005 Elsevier B.V All rights reserved.

Synthesis, characterization and thermal behaviour of solid-state compounds of light trivalent lanthanide succinates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Improved activity and stability of Ce-promoted Ni/γ-A1 2O3 catalysts for carbon dioxide reforming of methane

The CO2 reforming of CH4 was carried out over Ni catalysts supported on γ-Al2O3 and CeO 2-promoted γ-Al2O3. The catalysts were characterized by means of surface area measurements, TPR, CO2 and H2 chemisorption, XRD, SEM, and TEM. The CeO2 addition promoted an increase of catalytic activity and stability. The improvement in the resistance to carbon deposition is attributed to the highest CO2 adsorption presented by the CeO2 addition. The catalytic behavior presented by the samples, with a different CH4/CO2 ratio used, points to the CH4 decomposition reaction as the main source of carbon deposition.

La technique de l’arc segmenté. Contrôle de l’ancrage et modification significative du profil facial : une étude de cas

This article evaluates space closure mechanics efficiency in an extraction case where maximum anchorage was a requirement. The Segmented Arch Technique (SAT) was utilized as an anchorage control strategy to obtain maximum anterior retraction and, in consequence, significant facial profile change. A 20-year-10-month old woman needed severe labial and profile changes. The patient had four premolars extracted and SAT with type A mechanics [1] (Marcotte [2] activation protocol) was applied. The results showed significant reduction in labial protrusion and incisal angulation with effective anchorage control. The results were compared to others available in the literature derived from different techniques, where anterior retraction was also accomplished with maximum anchorage [3-7]. In conclusion, the SAT with type A mechanics has been shown to be another treatment option when significant changes in the soft-tissue profile are needed in extraction cases. © 2008. CEO. Published by Elsevier Masson SAS. All rights reserved.

Influence of the preparation method and the support on H2O 2electrogeneration using cerium oxide nanoparticles

This work describes the influence of the preparation method and the carbon support using a low contentof cerium oxide nanoparticles (CeO2/C 4%) on H2O2electrogeneration via the oxygen reduction reac-tion (ORR). For this purpose, the polymeric precursor (PPM) and sol-gel (SGM) methods with Vulcan XC72R (V) and Printex L6 (P) supports were employed. The materials were characterized by X-ray diffrac-tion (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TheXRD analysis identified two phases comprising CeO2and CeO 2-x. The smallest mean crystallite size wasexhibited for the 4% CeO2/C PPM P material, which was estimated using the Debye-Scherrer equation tobe 6 nm and 4 nm for the CeO2and the CeO 2-xphases, respectively, and was determined by TEM to be5.9 nm. XPS analysis was utilized to compare the oxygen content of the 4% CeO2/C PPM P to Printex L6.The electrochemical analysis was accomplished using a rotating ring-disk electrode. The results showedthat the 4% CeO2/C specimen, prepared by PPM and supported on Printex L6, was the best electrocatalystfor H2O2production in 1 mol L -1NaOH. This material showed the highest ring current, producing 88%H2O2and transferring 2.2 electrons per O 2molecule via the ORR at the lowest onset potential. Addition-ally, the ring-current of the 4% CeO2/C PPM P material was higher than that of Vulcan XC 72R and PrintexL6, the reference materials for H2O 2production, indicating the highest electrocatalytic activity for the 4%CeO2/C PPM P material. © 2013 Elsevier Ltd. All rights reserved.

Avaliação do risco de cárie e microbiota fúngica em pacientes pediátricos com anemia falciforme

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hipomineralização molar-incisivo: prevalência, severidade e etiologia em escolares de Araraquara

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação de marcadores moleculares de resposta à quimioterapia neoadjuvante e associação de radioterapia e quimioterapia em pacientes com carcinoma epidermóide de orofaringe

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação de quimiocinas séricas em mulheres com câncer epitelial de ovário

Pós-graduação em Ginecologia, Obstetrícia e Mastologia - FMB