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Bras P.,Instituto Superior Of Educacao E Ciencias | Miranda G.L.,University of Lisbon
Iberian Conference on Information Systems and Technologies, CISTI | Year: 2013

Liaw's attitude questionnaire towards computers and the World Wide Web (WWW), first published in 2002, has revealed good internal consistency but factorial problems over time. 'Attitudes' can predict people's behavior in certain situations, although the relationship between attitude and behavior is complex and multidimensional. Having reliable and valid instruments to measure variables is an essential condition for the credibility of a research. Thus, we developed a study to determine the psychometric characteristics of this questionnaire applied to a sample of Portuguese teachers. Based on this study, other professionals may apply this instrument safely. It should be noted that the validation of a measure instrument for the social sciences is an ongoing process. In other words, validation is always needed when applying the instruments on new samples. The accumulation of data is crucial to determine the stability and credibility of the instrument, evaluating results and leading to its improvement. © 2013 AISTI. Source

Martins F.,University of Lisbon | Leitao R.E.,Polytechnic Institute of Lisbon | Ventura M.C.,University of Lisbon | Ventura M.C.,Instituto Superior Of Educacao E Ciencias | And 2 more authors.
Journal of Molecular Liquids | Year: 2012

Refractive indices, n D, and densities, ρ, at 298.15 K were measured for the ternary mixture methanol (MeOH)/propan-1-ol (1-PrOH)/acetonitrile (MeCN) for a total of 22 mole fractions, along with 18 mole fractions of each of the corresponding binary mixtures, methanol/propan-1-ol, propan-1-ol/acetonitrile and methanol/acetonitrile. The variation of excess refractive indices and excess molar volumes with composition was modeled by the Redlich-Kister polynomial function in the case of binary mixtures and by the Cibulka equation for the ternary mixture. A thermodynamic approach to excess refractive indices, recently proposed by other authors, was applied for the first time to ternary liquid mixtures. Structural effects were identified and interpreted both in the binary and ternary systems. A complex relationship between excess refractive indices and excess molar volumes was identified, revealing all four possible sign combinations between these two properties. Structuring of the mixtures was also discussed on the basis of partial molar volumes of the binary and ternary mixtures. © 2012 Elsevier B.V. All rights reserved. Source

Santos H.A.F.A.,Instituto Superior Of Educacao E Ciencias
Acta Mechanica | Year: 2015

This paper addresses the development of a novel updated Lagrangian variational formulation and its associated finite element model for the geometrically nonlinear quasi-static analysis of cantilever beams. The formulation is based on an incremental complementary energy principle. The proposed finite element model only contains nodal bending moments as degrees of freedom. The model is used for the analysis of problems modeled by the so-called elastica theory. Numerical solutions satisfying all equilibrium equations in a strong sense can be obtained for arbitrarily large displacements and rotations. A Newton–Raphson method is adopted to trace the post-buckling response. Numerical results are presented and compared with those produced by the standard total Lagrangian two-node displacement-based finite element model. © 2014, Springer-Verlag Wien. Source

Pinheiro L.M.V.,University of Lisbon | Ventura M.C.M.M.,Instituto Superior Of Educacao E Ciencias | Moita M.L.C.J.,University of Lisbon
Journal of Molecular Liquids | Year: 2010

Quantitative Structure-Property Relationship methodology was applied successfully to experimental molar transition energies of quinoline, published before, in order to achieve a better understanding about the predominant quinoline-solvent interactions. Internal and external model validations were performed showing a high predictive ability of the selected multiple linear relationship. The wavenumbers of maximum absorbance of five dyes UV-vis spectra in methanol/dimethylformamide, propan-1-ol/dimethylformamide and pentan-1-ol/dimethylformamide mixtures, and in pure solvents, were experimentally determined, at 298.15 K, with the aim of calculating the Kamlet and Taft solvatochromic parameters (π, α and β). Refractive indices of those mixtures were also calculated, to evaluate the Lorentz-Lorenz function values, g(nD). The chosen solvatochromic response model of quinoline suggests the dominance of the dipolarity/polarizability (π) and the basicity (β) parameters followed by the ET N one (predominantly a measure of the solvent acidity). The former parameter contributes to a higher stabilization of the ground state and the two latter ones to a greater stabilization of the quinoline Frank-Condon excited state. © 2010 Elsevier B.V. All rights reserved. Source

Moita M.-L.C.J.,University of Lisbon | Reis M.C.,University of Lisbon | Reis M.C.,Instituto Superior Of Educacao E Ciencias | Santos A.F.S.,University of Lisbon | Lampreia I.M.S.,University of Lisbon
Journal of Chemical Thermodynamics | Year: 2015

Given the importance that enthalpic and entropic contributions have in the interplay between thermodynamics and self-assembly of aqueous amphiphile systems, the energetic characterisation of the system {water + 1-propoxypropan-2-ol (1-pp-2-ol)} at T = 298.15 K was made by directly measuring excess partial molar enthalpies of 1-pp-2-ol and water, over the entire composition range, at T = 298.15 K and atmospheric pressure. Derivatives of the partial molar properties with respect to the composition are used to improve the understanding of molecular interactions in the water-rich region. The present results were compared with those for the well-studied system {water + 2-butoxyethanol (nC4E1)}, the two amphiphiles being structural isomers. © 2015 Elsevier Ltd. All rights reserved. Source

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