Browsing by Author "Silva, C."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Blistering of W-Ta composites at different irradiation energiesPublication . Mateus, R.; Dias, M.; Lopes, J.; Rocha, J.; Catarino, N.; Duarte, P.; Gomes, R. B.; Silva, C.; Fernandes, H.; Livramento, V.; Carvalho, P. A.; Alves, E.; Hanada, K.; Correia, J. B.Pure tungsten and tantalum plates and tungsten-tantalum composites produced via mechanical alloying and spark plasma sintering were bombarded with He+ and D+ energetic ion beams and deuterium plasmas. The aim of this experiment is to study the effects caused by individual helium and deuterium exposures and to evidence that the modifications induced in the composites at different irradiation energies could be followed by irradiating the pristine constituent elements under the same experimental conditions, which is relevant considering the development of tailored composites for fusion applications. Higher D retentions, especially in tungsten, and superficial blistering are observed in both components after helium exposure. The blistering is magnified in the tantalum phase of composites due to its higher ductility and to water vapour production under deuterium irradiation. At lower irradiation energies the induced effects are minor. After plasma exposure, the presence of tantalum does not increase the D content in the composites. (C) 2013 Elsevier B.V. All rights reserved.
- Escritas inventadas no Jardim-de-Infância: comparando dois programas de intervençãoPublication . Almeida, Tiago; Silva, C.O objetivo deste estudo foi comparar o efeito de dois programas de treino em escritas inventadas na qualidade das produções escritas e leitura. Participaram 100 crianças que não sabiam ler nem escrever, distribuídas por quatrogrupos experimentais e um de controle. Os grupos 1 e 2 seguiram a metodologia de Alves Martins, Albuquerque, Salvador e Silva (2013) e os grupos 3 e 4 a metodologia de Ouellette, Sénéchal e Haley (2013). Nos grupos 1 e 3 utilizaram-se palavras facilitadoras cuja sílaba inicial coincide com o nome da letra e nos grupos 2 e 4 palavras facilitadoras cuja sílaba inicial coincide com o som. Os grupos 1 e 2 tiveram resultados superiores aos grupos 3, 4 e controle.
- Influence of the substrate on structure and magnetic properties of Co-N thin filmsPublication . Silva, C.; Vovk, A.; Silva, R.C. da; Strichonavec, P.; Algarabel, P.A.; Casaca, A.; Meneghini, C.; Carlomagno, I.; Godinho, M.; Cruz, M.M.Cubic cobalt nitride films were grown onto different single crystalline substrates Al2O3 (0 0 0 1) and (1 1 View the MathML source 0), MgO (1 0 0) and (1 1 0) and TiO2 (1 0 0) and (1 1 0). The films display low atomic densities compared with the bulk material, are ferromagnetic and have metallic electrical conductivity. X-ray diffraction and X-ray absorption fine structure confirm the cubic structure of the films and with RBS results indicate that samples are not homogeneous at the microscopic scale, coexisting Co4+xN nitride with nitrogen rich regions. The magnetization of the films decreases with increase of the nitrogen content, variation that is shown to be due to the decrease of the cobalt density, and not to a decrease of the magnetic moment per cobalt ion. The films are crystalline with a nitrogen deficient stoichiometry and epitaxial with orientation determined by the substrate.