Channel arrangements and depositional styles in the Sao Lourenco fluvial megafan, Brazilian Pantanal wetland

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

Second Phase Precipitation in Ultrafine-grained Ferrite Steel

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

Estabilidade da fixação antirrotacional lateral com parafuso associada à técnica de avanço de tuberosidade da tíbia

Pós-graduação em Cirurgia Veterinária - FCAV

Hot turning of a difficult-to-machine steel (sae xev-f) aided by infrared radiation

A possible way for increasing the cutting tool life can be achieved by heating the workpiece in order to diminish the shear stress of material and thus decrease the machining forces. In this study, quartz electrical resistances were set around the workpiece for heating it during the turning. In the tests, heat-resistant austenitic alloy steel was used, hardenable by precipitation, mainly used in combustion engine exhaustion valves, among other special applications for industry. The results showed that in the hot machining the cutting tool life can be increased by 340% for the highest cutting speed tested and had a reduction of 205% on workpiece surface roughness, accompanied by a force decrease in relation to conventional turning. In addition, the chips formed in hot turning exhibited a stronger tendency to continuous chip formation indicating less energy spent in material removal process. Microhardness tests performed in the workpieces subsurface layers at 5 m depth revealed slightly higher values in the hot machining than in conventional, showing a tendency toward the formation of compressive residual stress into plastically deformed layer. The hot turning also showed better performance than machining using cutting fluid. Since it is possible to avoid the use of cutting fluid, this machining method can be considered better for the environment and for the human health.

Surface modification of polymeric materials by cold atmospheric plasma jet

In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40 degrees in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure. (C) 2014 Elsevier B.V. All rights reserved.

Sn(1-x)LaxO2 thin films deposited on AISI 304 stainless steel substrates

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nonlinear formulation based on FEM, Mazars damage criterion and Fick's law applied to failure assessment of reinforced concrete structures subjected to chloride ingress and reinforcements corrosion

Structural durability is an important design criterion, which must be assessed for every type of structure. In this regard, especial attention must be addressed to the durability of reinforced concrete (RC) structures. When RC structures are located in aggressive environments, its durability is strongly reduced by physical/chemical/mechanical processes that trigger the corrosion of reinforcements. Among these processes, the diffusion of chlorides is recognized as one of major responsible of corrosion phenomenon start. To accurate modelling the corrosion of reinforcements and to assess the durability of RC structures, a mechanical model that accounts realistically for both concrete and steel mechanical behaviour must be considered. In this context, this study presents a numerical nonlinear formulation based on the finite element method applied to structural analysis of RC structures subjected to chloride penetration and reinforcements corrosion. The physical nonlinearity of concrete is described by Mazars damage model whereas for reinforcements elastoplastic criteria are adopted. The steel loss along time due to corrosion is modelled using an empirical approach presented in literature and the chloride concentration growth along structural cover is represented by Fick's law. The proposed model is applied to analysis of bended structures. The results obtained by the proposed numerical approach are compared to responses available in literature in order to illustrate the evolution of structural resistant load after corrosion start. (C) 2014 Elsevier Ltd. All rights reserved.

Optimized design of substrate-integrated hollow waveguides for mid-infrared gas analyzers

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Geometry effects on the electronic properties of multi-open dots structures

In this paper we show that the electronic properties of multi-open dots structures are strongly modified by even smalt changes in their geometries. Our discussion of these effects is done in terms of the interaction among localized states (dot-like) and extended states (channel-like), from which a Fano resonance situation arises.

Long-range and short-range structures of cube-like shape SrTiO3 powders: microwave-assisted hydrothermal synthesis and photocatalytic activity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cerâmicas porosas a base de zircônia na forma de filmes suportados preparados a partir de emulsões

Pós-graduação em Química - IQ

Sodium intake combining cholinergic activation and noradrenaline into the lateral parabrachial nucleus

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

Influência do tratamento térmico de homogeneização na microestrutura de um aço utilizado na fabricação de cilindros de laminação para trabalho a frio

Pós-graduação em Engenharia Mecânica - FEG

Interaction between recrystallization and strain-induced precipitation in a high Nb- and N-bearing austenitic stainless steel: influence of the interpass time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Developmental Morphology of a Dimorphic Grass Inflorescence: The Brazilian Bamboo Eremitis (Poaceae)

Premise of research.The highly specialized grass inflorescence varies with respect to phyllotaxis, with the reproductive meristem forming primary lateral branches that are either spirally arranged or distichous. The Brazilian bamboo Eremitis is highly unusual in that it has a dimorphic inflorescence, typically composed of an apical gynecandrous whorl of both male and female spikelets and basal whorls of male spikelets. Although not closely related to them, Eremitis shares some structural similarities with some early-divergent grasses.Methodology.We use SEM and LM to describe the development of the reproductive structures of Eremitis to clarify our understanding of the highly specialized grass inflorescence and flower.Pivotal results.Developmental studies show that the inflorescence of Eremitis is actually partially whorled and partially distichous. The apical whorl is abortive. The female spikelet is not terminal on the axis, in contrast with the majority of grasses. All the male spikelets are distichously attached to the inflorescence axis and separated into groups. There is a hollow style with two vascular bundles.Conclusions.The strong morphological similarities between Eremitis and some early-divergent grasses are here supplemented by several anatomical similarities, perhaps due to a shared pollination syndrome.