Browsing by Issue Date, starting with "2014-10"
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- Nonverbal communication in the learning processPublication . Moreira, Darlinda
- Tris(2-Ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part II: Density measurements at temperatures from (293 to 373) K and pressures up to 68MPaPublication . Diogo, João C. F.; Avelino, Helena Maria da Nóbrega Teixeira; Caetano, Fernando J. P.; Fareleira, João M. N. A.In Part I of the present work we describe the viscosity measurements performed on tris(2-ethylhexyl) trimellitate or 1,2,4-benzenetricarboxylic acid, tris(2-ethylhexyl) ester (TOTM) up to 65MPa and at six temperatures from (303 to 373) K, using a new vibrating-wire instrument. The main aim is to contribute to the proposal of that liquid as a potential reference fluid for high viscosity, high pressure and high temperature. The present Part II is dedicated to report the density measurements of TOTM necessary, not only to compute the viscosity data presented in Part I, but also as complementary data for the mentioned proposal. The present density measurements were obtained using a vibrating U-tube densimeter, model DMA HP, using model DMA5000 as a reading unit, both instruments from Anton Paar GmbH. The measurements were performed along five isotherms from (293 to 373)K and at eleven different pressures up to 68MPa. As far as the authors are aware, the viscosity and density results are the first, above atmospheric pressure, to be published for TOTM. Due to TOTM’s high viscosity, its density data were corrected for the viscosity effect on the U-tube density measurements. This effect was estimated using two Newtonian viscosity standard liquids, 20 AW and 200 GW. The density data were correlated with temperature and pressure using a modified Tait equation. The expanded uncertainty of the present density results is estimated as 0.2% at a 95% confidence level. Those results were correlated with temperature and pressure by a modified Tait equation, with deviations within 0.25%. Furthermore, the isothermal compressibility, kT, and the isobaric thermal expansivity, ap, were obtained by derivation of the modified Tait equation used for correlating the density data. The corresponding uncertainties, at a 95% confidence level, are estimated to be less than 1.5% and 1.2%, respectively. No isobaric thermal expansivity and isothermal compressibility for TOTM were found in the literature.
- Educação a distância e elearning na web socialPublication . Moreira, J. António; Barros, Daniela Melaré Vieira; Monteiro, Angélica"Num momento historicamente marcado por intensas transformações mundiais, este livro traz elementos, ideias, conceitos e expressões-manifestações atuais para o campo educacional e, fundamentalmente, faz um convite ao diálogo sobre a Educação contemporânea (…). As tendências recheiam-se de artefatos e espaços: gameficação, plataformas digitais, comunicação por nuvem, celulares, smartphones, tablets e paredes holográficas, inteligência artificial, redes sociais, dispositivos móveis; geolocalização, conteúdo aberto, REA (Recursos Educacionais Abertos), MOOC (Cursos Online Abertos e Massivos), POMAR (Percursos Online Massivos Abertos e Rizomáticos), aplicações semânticas, software livre, hibridização, Educação Aberta, docência online, redes rizomáticas, linguagem emocional, mediação partilhada, interatividade etc., nomeiam e sinalizam as transformações socioeducacionais.” Adriana Rocha Bruno
- O uso estratégico do ato de asserção num corpus de ‘histórias de vida’ realizadas em contexto de entrevistaPublication . Almeida, Carla Aurélia deTaking as reference an oral corpus of life histories collected in interviews, this paper proposes an analysis of the act of assertion within the framework of speech acts theory and of P. Attal's propositions. First, we consider the functioning of evaluative assertions with positive axiological value. Second, we focus on assertions with a negative axiological value and we analyse the interactional role of fuzziness markers: diminutives as softeners, adjectives' evaluative suffixes, sequences of justification as “mitigatory comments” and tag questions. Finally, we study the strategic use of assertions with impersonal references and of agreement assertions with Extreme Case Formulations.
- Princípios de gestão : enquadramento geral : aula 1Publication . Carvalho, Luísa
- Caros estudantes: queiram entrar e juntar-se a nós!Publication . Moreira, Darlinda
- Tris(2-ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part I: Viscosity measurements at temperatures from (303 to 373) K and pressures up to 65MPa, using a novel vibrating-wire instrumentPublication . Diogo, João C. F.; Avelino, Helena Maria da Nóbrega Teixeira; Caetano, Fernando J. P.; Fareleira, João M. N. A.The article reports viscosity measurements of compressed liquid tris(2-ethylhexyl) trimellitate or 1,2,4- Benzenetricarboxylic acid, tris(2-ethylhexyl) ester (TOTM) which is an important plasticizer in the polymer industry and has wide applications as a lubricant. Nevertheless, the main motivation for the present work is to propose TOTM as a plausible candidate for an industrial viscosity reference fluid for high viscosity, high pressure and high temperature. This kind of reference fluid is presently on demand by oil industries and the International Association for Transport Properties is developing efforts aiming to select appropriate candidates and to establish the corresponding reference data. The viscosity measurements were performed with a novel vibrating wire sensor. The new instrument was designed for operation at high pressures (up to 100MPa) and temperatures up to 373 K. The present measurements were obtained using the vibrating wire sensor in the forced oscillation or steady-state mode of operation. The viscosity measurements were carried out up to 65MPa and at six temperatures from (303 to 373) K. The viscosity results were correlated with density, using a modified hard-spheres scheme. The root mean square deviation of the data from the correlation is 0.53% and the maximum absolute relative deviation was less than 1.7%. The expanded uncertainty of the present viscosity results, at a 95% confidence level, is estimated to be less than 2% for viscosities up to 68mPa s, less than 2.6% for viscosities between (69 and 268) mPas and less than 3% for higher viscosities. The TOTM density data necessary to compute the viscosity results were measured using a vibrating Utube densimeter, model DMA HP and are described in part II of the present work. No literature data above atmospheric pressure could be found for the viscosity of TOTM. As a consequence, the present viscosity results could only be compared upon extrapolation of the vibrating wire data to 0.1 MPa. Independent viscosity measurements were performed, at atmospheric pressure, using an Ubbelohde capillary in order to compare with the vibrating wire results, extrapolated by means of the above mentioned correlation. The two data sets agree within 1%, which is commensurate with the mutual uncertainty of the experimental methods. Comparisons of the literature data obtained at atmospheric pressure with the present extrapolated vibrating-wire viscosity measurements have shown an agreement within 2% for temperatures up to 339K and within 3.3% for temperatures up to 368 K.
- Princípios de gestão : desafios que se colocam à gestão moderna : aula 2Publication . Carvalho, Luísa
- Viscosity measurements on Ionic liquids : a cautionary talePublication . Diogo, João C. F.; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Wakeham, William A.The vibrating-wire viscometer has proven to be an exceedingly effective means of determining the viscosity of liquids over a wide range of temperature and pressure. The instrument has a long history but a variety of technological and theoretical developments over a number of years have improved its precision and most recently have enabled absolute measurements of high accuracy. However, the nature of the electrical measurements required for the technique has inhibited its widespread use for electrically conducting liquids so that there have been only a limited number of measurements. In the particular context of ionic liquids, which have themselves attracted considerable attention, this is unfortunate because it has meant that one primary measurement technique has seldom been employed for studies of their viscosity. In the last 2 years systematic efforts have been made to explore the applicability of the vibrating-wire technique by examining a number of liquids of increasing electrical conductivity. These extensions have been successful. However, in the process we have had cause to review previous studies of the viscosity and density of the same liquids at moderate temperatures and pressures and significant evidence has been accumulated to cause concern about the application of a range of viscometric techniques to these particular fluids. Because the situation is reminiscent of that encountered for a new set of environmentally friendly refrigerants at the end of the last decade, in this paper the experimental methods employed with these liquids have been reviewed which leads to recommendations for the handling of these materials that may have consequences beyond viscometric measurements. In the process new viscosity and density data for 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [C6mim][NTf2], 1-ethyl-3-methylimidazolium ethyl sulfate [C2mim][EtSO4], and 1-ethyl-3-methylpyridinium ethyl sulfate [C2mpy][EtSO4] have been obtained.
- Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized studyPublication . Machado, Humberto S.; Nunes, Catarina S.; Sá, Paula; Couceiro, António; Silva, Álvaro Moreira da; Águas, ArturBackground Mechanical ventilation is a well–known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation. Methods A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy. Results All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis. Conclusions Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.