Browsing by Issue Date, starting with "1992"
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- A cidade de FaustoPublication . Ribeiro, Carlos"A Cidade de Fausto", é uma peça de teatro que tem como ponto de partida o mito de Fausto. O desenvolvimento da peça centra-se em torno de uma meditação cénica sobre o saber viver em comunidade. A comunidade teatral, os actores e as personagens, servem esse objectivo de um micro-laboratório social, tragicómico, onde se ensaiam, estratégias de colaboração e convivência que passam pela multiplicidade de registos que espelham, por sua vez, a diversidade característica da Cidade. Esta Cidade plural encontra na poesia cénica, que esbate lirismo e ironia, o magma em que se refaz. Fausto torna-se pois sinónimo de um “simulado incêndio”, porventura imperdoável.
- Eça de Queiroz e a modaPublication . Morais-Alexandre, PauloRESUMO: Eça de Queiroz foi uma personalidade impar da literatura portuguesa, sendo as suas obras reflexo do tempo que viveu e da sociedade em que se integrou, verificando-se que estas, estão recheadas de referências à indumentária e às modas que se iam sucedendo e que muitas vezes descreveu. Dos indícios documentais biográficos, releva uma relação com a indumentária pessoal muito atenta e cuidada quase podendo ser considerado um dandy.
- The effect of the angle of incidence on the aqueous corrosion of ion implanted M50 steel substratesPublication . Rangel, C. N.; Simplício, M. H.; Consiglieri, A. C.; Nielsen, B. R.; Torp, B.; Teixeira, Nuno; Alves, J. G.; Silva, M. F. da; Soares, J. C.; Dodd, A.; Kinder, J.Following work on tantalum and chromium implanted flat M50 steel substrates, this work reports on the electrochemical behaviour of M50 steel implanted with tantalum and chromium and the effect of the angle of incidence. Proposed optimum doses for resistance to chloride attack were based on the interpretation of results obtained during long-term and accelerated electrochemical testing. After dose optimization from the corrosion viewpoint, substrates were implanted at different angles of incidence (15°, 30°, 45°, 60°, 75°, 90°) and their susceptibility to localized corrosion assessed using open-circuit measurements, step by step polarization and cyclic voltammetry at several scan rates (5–50 mV s-1). Results showed, for tantalum implanted samples, an ennoblement of the pitting potential of approximately 0.5 V for an angle of incidence of 90°. A retained dose of 5 × 1016 atoms cm-2 was found by depth profiling with Rutherford backscattering spectrometry. The retained dose decreases rapidly with angle of incidence. The breakdown potential varies roughly linearly with the angle of incidence up to 30° falling fast to reach -0.1 V (vs. a saturated calomel electrode (SCE)) for 15°. Chromium was found to behave differently. Maximum corrosion resistance was found for angles of 45°–60° according to current densities and breakdown potentials. Cr+ depth profiles ((p,γ) resonance broadening method), showed that retained doses up to an angle of 60° did not change much from the implanted dose at 90°, 2 × 1017 Cr atoms cm-2. The retained implantation dose for tantalum and chromium was found to follow a (cos θ)8/3 dependence where θ is the angle between the sample normal and the beam direction.
- Interdiffusion at Sb/Ge interfaces induced in thin multilayer films by nanosecond laser irradiationPublication . Serna, R.; Afonso, C. N.; Catalina, F.; Teixeira, Nuno; Silva, M. F. da; Soares, J. C.Thin films consisting of 3 or 4 Sb and Ge alternating layers are irradiated with single nanosecond laser pulses (12 ns, 193 nm). Real time reflectivity (RTR) measurements are performed during irradiation, and Rutherford backscattering spectrometry (RBS) is used to obtain the concentration depth profiles before and after irradiation. Interdiffusion of the elements takes place at the layer interfaces within the liquid phase. The reflectivity transients allow to determine the laser energy thresholds both to induce and to saturate the process being both thresholds dependent on the multilayer configuration. It is found that the energy threshold to initiate the process is lower when Sb is at the surface while the saturation is reached at lower energy densities in those configurations with thinner layers.
- Microscopic Theory of Anchoring Transitions at the Surfaces of Pure Liquid-Crystals and their Mixtures .1. The Fowler ApproximationPublication . Teixeira, Paulo; Sluckin, T. J.We have generalized earlier work on anchoring of nematic liquid crystals by Sullivan, and Sluckin and Poniewierski, in order to study transitions which may occur in binary mixtures of nematic liquid crystals as a function of composition. Microscopic expressions have been obtained for the anchoring energy of (i) a liquid crystal in contact with a solid aligning surface; (ii) a liquid crystal in contact with an immiscible isotropic medium; (iii) a liquid crystal mixture in contact with a solid aligning surface. For (iii), possible phase diagrams of anchoring angle versus dopant concentration have been calculated using a simple liquid crystal model. These exhibit some interesting features including re-entrant conical anchoring, for what are believed to be realistic values of the molecular parameters. A way of relaxing the most drastic approximation implicit in the above approach is also briefly discussed.