Cenário de emissão contínua de partículas em colisões nucleares relativísticas

Pós-graduação em Física - IFT

Influxos do céu na existência dos homens. Os escritos astrológicos na Península Ibérica (séculos XIII, XIV e XV)

Pós-graduação em História - FCHS

O mirabolante mundo das partículas elementares: uma sequência didática para professores de física

Pós-graduação em Ensino de Física (mestrado profissional) - FCT

Sílica mesoporosa como suporte sólido para o ancoramento da molécula 4-amino-3-hidrazino-5-mercapto-1,2,4-triazole e aplicação na adsorção de Cu(II), Cd(II), Ni(II), Pb(II) e Co(II) em amostras aquosas

Pós-graduação em Química - IQ

Alguns aspectos da transposição de uma sequencia didática sobre o comportamento de partículas e ondas

This work presents a partial analysis of the implementation of a didactic sequence aimed at undergraduate students of quantum chemistry. The sequence develops on some fundamental concepts to understand the behavior of the objects particles and waves in the doubleslit experiment. The analysis is based on the didactic transposition theory, proposed by Yves Chevallard, which allows reflection upon the scientific knowledge reorganized to be used in teaching contexts. Our interest in this study lays on the dynamics of transposition of knowledge-to-be-taught into knowledge-taught, particularly the importance of making concepts more comprehensible. Results showed that the communication of knowledge by the students is presented with interruptions, gaps and colloquial language. The analysis allowed the identification of needs and possibilities of learning, as well as a turn in the teacher practice, through a dynamic process of action and reflection.

Vacuum infiltration of copper aluminate by liquid aluminium

This paper studies attained microstructures and reactive mechanisms involved in vacuum infiltration of copper aluminate preforms with liquid aluminium. At high temperatures, under vacuum, the inherent alumina film enveloping the metal is overcome, and aluminium is expected to reduce copper aluminate, rendering alumina and copper. Under this approach, copper aluminate toils as a controlled infiltration path for aluminium, resulting in reactive wetting and infiltration of the preforms. Ceramic preforms containing a mixture of Al2O3 and CuAl2O4 were infiltrated with aluminium under distinct vacuum levels and temperatures, and the resulting reaction and infiltration behaviour is discussed. Copper aluminates stability ranges depend on vacuum level and oxygen partial pressure, which determine both CuAl2O4 and CuAlO2 ability for liquid aluminium infiltration. At 1100 °C and 0.76 atm vacuum level CuAl2O4 is stable, indicating pO2 above 0.11 atm. Reactive infiltration is achieved via reaction between aluminium and CuAl2O4; however, fast formation of an alumina film blocking liquid aluminium wicking results in incipient infiltration. At 1000 °C and 3.8 × 10−7 atm vacuum level, CuAlO2 decomposes to Cu and Al2O3 indicating a pO2 below 6.0 × 10−7 atm; infiltration of the ceramic is hindered by the non-wetting behaviour of the resulting metal alloy. At 1000 °C and 1.9 × 10−6 atm vacuum level CuAlO2 is stable, indicating pO2 above 6.0 × 10−7 atm. Extensive infiltration is achieved via redox reaction between aluminium and CuAlO2, rendering a microstructure characterised by uniform distribution of alumina particles amid an aluminium matrix. This work evidences that liquid aluminium infiltration upon copper aluminate-rich preforms is a feasible route to produce Al–matrix alumina-reinforced composites. The associated reduction reaction renders alumina, as fine particulate composite reinforcements, and copper, which dissolves in liquid aluminium contributing as a matrix strengthener.

Al2O3 Obtained through resistive evaporation for use as insulating layer in transparent field effect transistor

Alumina thin films have been obtained by resistive evaporation of Al layer, followed by thermal oxidation achieved by annealing in appropriate atmosphere (air or O2-rich), with variation of annealing time and temperature. Optical and structural properties of the investigated films reveal that the temperature of 550°C is responsible for fair oxidation. Results of surface electrical resistivity, Raman and infrared spectroscopies are in good agreement with this finding. X-ray and Raman data also suggest the crystallization of Si nuclei at glass substrate-alumina interface, which would come from the soda-lime glass used as substrate. The main goal in this work is the deposition of alumina on top of SnO2 to build a transparent field-effect transistor. Some microscopy results of the assembled SnO2/Al2O3 heterostructure are also shown.

Tribocorrosion behaviour of hot pressed CoCrMo−Al2O3 composites for biomedical applications

Alumina/alumina wear couple can lower the wear rates and thus metallic ion releasing on load bearing metallic implant materials. However, the low fracture toughness of ceramics is still a major concern. Therefore, the present study aims to process and to triboelectrochemically characterise the 5 and 10 vol.-%Al2O3 reinforced CoCrMo matrix composites. Corrosion and tribocorrosion behaviour of the composites were investigated in 8 g L−1 NaCl solution at body temperature. Corroded and worn surfaces were investigated by a field emission gun scanning electron microscope equipped with energy dispersive X-ray spectroscopy. After tribocorrosion experiments, wear rates were calculated using a profilometer. Results suggest that Al2O3 particle addition decreased the tendency of CoCrMo alloy to corrosion under both static and tribocorrosion conditions. However, no significant influence on the corrosion and wear rates was observed in composites mainly due to increased porosity and insufficient matrix/reinforcement bonding.

Segmentação de imagens utilizando competição e cooperação entre partículas

Este artigo apresenta uma proposta de extensão do modelo de aprendizado semi-supervisionado conhecido como Competição e Cooperação entre Partículas para a realização de tarefas de segmentação de imagens. Resultados preliminares mostram que esta é uma abordagem promissora.

Adsorção de metais em solução aquosa pelos processos de batelada e coluna de leito fixo utilizando silsesquioxano funcionalizado com 5-amino-1,3,4-tiadiazol-2-tiol

Pós-graduação em Ciência dos Materiais - FEIS

Minhocão: entre o céu e o chão. Metamorfoses espaciais na metrópole paulistana

Apresentando-se como um complexo aparato urbano em uma localidade já tão heterogênea na área central da cidade de São Paulo, o Minhocão divide bairros e opiniões. O trabalho presente propõe-se a apresentar suas diversas facetas, os usos a que a população destina o Elevado Costa e Silva e desconstruiruir seus paradigmas. Analisar sua multiplicidade, e por fim, apresentar um projeto de intervenção apoiado em referências teóricas e projetuais, levando-se em consideração as singularidades desta via elevada

Avaliação mecânica e microbiológica de resinas acrílicas reforçadas com partículas de sílica revestidas com prata

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evolução diurna e anual da frequência das coberturas de céu em Botucatu/SP

This work presents an analysis of the pattern variation of the sky conditions in Botucatu/SP. The classification was based on the clarness index KT. It was used in the classification a database of global solar irradiance in the horizontal, measured at Radiometric Station of UNESP in Botucatu (latitude 22.85°S, longitude 48.43°W, altitude 786 m) from 1996 to 2005. We analyzed the variations in frequency, during the photoperiod and over the year, of the sky conditions: I - Cloudy (KT < 0.35); II - party cloudy with dominance for the diffuse (0.35 < 0.55 < KT)) III - party cloudy with dominance for the clear (0.55 < KT < 0.65) and IV - clear (KT > 0.65). The frequency of sky conditions I and II are higher during the rainy season of the year and in hours close to sunrise and sunset. And it is lower during the dry season an in hours near noon, in wich there is a predominance of sky conditions III and IV. The monthly hourly frequency of sky condition I ranged from 46,91% of the photoperiod in January to 25.27% in August. And the frequency monthly daily ranged from nine days in January to three days in August. To the sky condition IV, the frequency monthly hourly ranged from 38.81% of the photoperiod in August to 18.17% im January. And the frequency monthly daily ranged from 17 days in August to three days in January.

Modelagem e simulação de transferência de calor em leito de partículas estacionárias sujeito a agitação intermitente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Termodinâmica de um conjunto de partículas em um bilhar bidimensional dependente do tempo: um gás bidimensional simplificado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)