Influência do desbalanceamento da onda retangular na liga de alumínio 6063-T6 soldada pelo processo TIG-CA

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Corrosion resistance of Ni-Cr alloys in different mouthwashes

Several alloys have been used for prosthodontics restorations in the last years. These alloys have a number of metals that include gold, palladium, silver, nickel, cobalt, chromium and titanium and they are used in oral cavity undergo several corrosion. Corrosion can lead to poor esthetics, compromise of physical properties, or increased biological irritation. The objective of this study was evaluated corrosion resistance of two alloys Ni-Cr and Ni-Cr-Ti in three types of mouthwashes with different active ingredients: 0.5g/l cetylpyridinium chloride + 0.05% sodium fluoride, 0.05% sodium fluoride + 0.03% triclosan (with fluor) and 0.12% chlorohexidine digluconate. The potentiodynamic curves were performed by means of an EG&G PAR 283 potentiostat/galvanostat. The counter electrode was a platinum wire and reference electrode was an Ag/AgCl, KCl saturated. Before each experiment, working electrodes were mechanically polished with 600 and 1200 grade papers, rinsed with distilled water and dried in air. All experiments were carried out at 37.0oC in conventional three-compartment double wall glass cell containing mouthwashes. The microstructures of two alloys were observed in optical microscopy. Analysis of curves showed that Ni-Cr alloy was less reactive in the presence of 0.12% chlorohexidine digluconate while Ni-Cr-Ti alloy was more sensitive for others two types of mouthwashes (0.5g/l cetylpyridinium chloride + 0.05% sodium fluoride  and 0.05% sodium fluoride + 0.03% triclosan). This occurred probably due presence of titanium in this alloy. Microstructural analysis reveals the presence of dendritic and eutectic microstructures for NiCr and Ni-Cr-Ti, respectively.

Fluoretação das águas de abastecimento público em um município com diferentes fontes de captação

Maintaining the levels of fluoride ion in public water supply within the parameters of adequacy it becomes essential so the measure carries a greater impact on caries prevention and control, without increasing the prevalence of dental fluorosis. Thus, it is necessary a rigorous control of the process, avoiding the undesired effects at levels above recommended levels, as well as avoiding levels below the recommended that do not offer the highest benefit. The aim of this study was to analyze the content of fluoride in public water supply in the city of Birigui, SP, with different sources of supply, checking if the fluoride levels are within the recommended. The samples were collected monthly from points previously established, with the knowledge of the distribution network of water and identifying the amount and location of supply sources and water treatment plant. Analyses were performed in duplicate in the period from January to December of 2009, in the laboratory - NEPESCO - of the Dental School of Araçatuba, Univ Estadual Paulista – UNESP, using an ion analyzer coupled to a specific electrode for fluoride. Of the total samples (n = 512), 44% (n = 224) had adequate levels and 56% (n = 288) inadequate levels, 10% (n = 49) lower levels and 46% (n = 239) showed levels above the recommended. There were differences in results when comparing the analysis of different sources. The fluoride concentration in the majority of the samples from deep wells was classified as inadequate not offering the desired benefit, or exposing the population to the risk of dental fluorosis.

Fluoretação das águas de abastecimento público no município de Araçatuba/SP

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

Modificação de eletrodos de carbono vítreo e nanotubos de Ti/TiO2 com aspirinato de cobre (II) para detecção eletroquímica e redução fotoeletrocatalítica de íons nitrito

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Imunossensor impedimétrico e dispositivo compreendendo o mesmo

Imunossensor impedimétrico e dispositivo compreendendo o mesmo. O presente pedido de patente revela um dispositivo de detecção impedimétrico voltado a áreas críticas de contaminação microbiana, compreendendo um eletrodo construído a partir de monocamadas autoorganizadas e proteína a imobilizadas na superfície de seu transdutor. A avaliação da contaminação microbiana é efetuada por meio da sucção da atmosfera interna do ambiente, interação Ag-Ac e detecção por impedância eletroquímica.

Estudo do efeito do transporte de massa nas curvas de polarização potenciodinâmica em ligas de alumínio da série 7XXX de aplicação aeronáutica

Aluminum Alloys are widely used as structural materials in the aerospace industry due to low weight, high mechanical strength and enduring corrosion resistance. Their resistance to corrosion is attributed to the rapidly formed stable oxide film (Al2O3) which spontaneously forms itself on the surface of the material. However, in the presence of aggressive ions, such as halide, Aluminum Alloys are subject to a localized process of corrosion. The electrochemical behavior of 7081-T73511 and 7050-T7451 Aluminum Alloys employed in the aerospace industry was investigated using a 0.6 M NaCl solution under the conditions of a controlled mass transport employing a rotating disk electrode. The theoretical limiting current density was determined by the Kouteki-Levich equation. The results confirmed that the inter-metallic Al7Cu2Fe acts as preferential cathode generating the galvanic coupling and the dissolution of the Aluminummatrix around it.

Preparação, caracterização e aplicação eletroanalítica de nanopartículas de hexacianoferrato (III) de zinco

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da resposta dielétrica e varistora de compostos cerâmicos multifásicos à base de Ca2CU2Ti4-xSnxO12 (0,0 < x< 4,0)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência de pressões de trabalho, espaçamentos e altura de instalação na distribuição de água de aspersor autocompensante

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Crescimento epitaxial e caracterização de filmes finos: óxidos condutores e ferroelétricos preparados por deposição de solução química

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

Ressonâncias planetárias spin-órbita com perturbação de terceiro corpo

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

Determinação de açucares em bagaço de palha de cana-de-açúcar por cromatografia líquida de alta eficiência com detecção eletroquímica utilizando eletrodos de nanotubos modificados com óxidos metálicos

Pós-graduação em Química - IQ

Desinfecção fotoeletrocatalítica de águas contaminadas com Candida Parapsilosis utilizando eletrodos de W/WO3 em tratamento fotoeletrocatalítico

Pós-graduação em Química - IQ

Dispositivo de microdescargas em gases na pressão atmosférica

This work describes the development of an electro-mechanical micro-discharges device operating at ambient condition of pressure and temperature, capable to produce plasma jets for surface finishing. The discharges are produced through a needle shape electrode hollow cathode type by which flows the helium gas. The voltage applied on the electrode is provided for an AC/AC switching voltage converter of full-bridge topology. The converter is energized by a power line of 110/220 VAC, 60 Hz and gives a 1000 V peak-to-peak from 5 kHz to 40 kHz square waveform output. The output frequency is defined by a control signal provided by an external signal generator. The equipment setup includes output acquisition of voltage and current and a photo-detector for photo-electrical measurements, which allows an optical characterization of the plasma jet