Publications

Abstract The knowledge of the liquid-liquid equilibria (LLE) between ionic liquids (ILs) and water is of utmost importance for environmental monitoring, process design and optimization. Therefore, in this work, the mutual solubilities with water, for the ILs combining the 1-methylimidazolium, [C(1)im](+); 1-ethylimidazolium, [C(2)im](+); 1-ethyl-3-propylimidazolium, [C(2)C(3)im](+); and 1-butyl-2,3-dimethylimidazolium, [C(4)C(1)C(1)im](+) cations with the bis(trifluoromethylsulfonyl)imide anion, were determined and compared with the isomers of the symmetric 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)C(n)im][NTf2], with n=1-3) and of the asymmetric 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)C(1)im][NTf2], with n = 2-5) series of ILs. The results obtained provide a broad picture of the impact of the IL cation structural isomerism, including the number of alkyl side chains at the cation, on the water-IL mutual solubilities. Despite the hydrophobic behaviour associated to the [NTf2](-) anion, the results show a significant solubility of water in the IL-rich phase, while the solubility of ILs in the water-rich phase is much lower. The thermodynamic properties of solution indicate that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Using the results obtained here in addition to literature data, a correlation between the solubility of [NTf2]-based ILs in water and their molar volume, for a large range of cations, is proposed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was also used to estimate the LLE of the investigated systems and proved to be a useful predictive tool for the a priori screening of ILs aiming at finding suitable candidates before extensive experimental measurements.

Abstract The vapour pressures of the liquid phase of 1-methylpyrazole, 1-methylbenzimidazole and 1-methylindole were measured over the temperature ranges (253.9 to 293.3) K, (303.2 to 372.5) K, and (268.6 to 341.9) K, respectively, using a static method. The vapour pressures of the crystalline phase of the two latter compounds were also measured at temperatures between (301.2 to 328.9) K and (267.6 to 275.5) K, respectively. The results obtained enabled the determination of the standard molar enthalpies and entropies of sublimation and of vaporisation at the mean temperatures of the measurements and at T = 298.15 K. The temperatures and molar enthalpies of fusion were determined using differential scanning calorimetry. The enthalpies of the intermolecular hydrogen bonds N-H center dot center dot center dot N in the crystalline phase of benzimidazole and pyrazole were determined and compared with the result previously determined for the energy of the intermolecular hydrogen bond in crystalline imidazole.

Abstract Vapour pressures of condensed phases of p-monohalophenols were measured over the temperature ranges (265.6 to 342.8) K, (273.5 to 331.0) K, (285.3 to 370.5) K and (307.2 to 380.4) K, respectively for p-fluoro, p-chloro, p-bromo and p-iodophenol, using a static method based on diaphragm capacitance gauges. The results obtained for each compound, enabled the determination of the standard molar enthalpies, Gibbs energies and entropies of sublimation and of vaporisation, at T = 298.15 K as well as phase diagram representations of the (p, T) experimental results. The temperatures and molar enthalpies of fusion were determined using DSC and were compared with the values derived from the vapour pressure measurements. Correlations involving thermodynamic properties and also the volume of the halogen substituent of p-halophenols are presented and compared to the ones derived before for related methyl p-halobenzoates and p-halobenzoic acids. Vapour pressures, at T = 298.15 K, of the compounds included in the three families are well described by a single correlation based on the temperature of fusion and on the volume of the halogen atom.

Abstract Highly pure samples of 4-nitro-phenyl azide, 1-octyl azide and 1 decyl-azide were prepared for thermochemical studies. Vapour pressures over the solid and the liquid sample of 4-nitro-phenyl azide have been determined by the transpiration method. The molar enthalpies of vaporization/sublimation for this compound were derived from the temperature dependencies of vapour pressures. The molar enthalpy of fusion of 4-nitro-phenyl azide was measured by DSC. The measured data set for 4-nitrophenyl azide was successfully checked for internal consistency. Molar enthalpies of vaporization of 1-octyl azide and 1 decyl-azide were measured by transpiration. The molar enthalpies of formation of the liquid 1-octyl azide and 1 decyl-azides were derived from the combustion calorimetry. New experimental results for these organic azides have been used to derive their molar enthalpies of formation in the gas state and for comparison with results from quantum-chemical method G4.

Abstract This Letter focuses the binding between Checkpoint kinase 1 and two molecules with known inhibition potential, C39 and C40. In order to find the most relevant residues the structures were submitted to an optimization process. As expected C39 presented the highest inhibitory power towards Chk1, being this inhibition mode highly dependent on the interactions with Lys38 and Glu91. Glu55 and Asp148 exhibit unfavorable interactions to C39. Glu91 was the most important residues in the binding of C40 to Chk1, while interaction with Lys38, Glu55 and Gly90 resulted in repulsion.

Abstract The relationships among structural and thermodynamic properties of 2-, 3-, and 4-chlorobenzonitrile were investigated, in the present work, using several experimental techniques (Knudsen effusion, differential scanning calorimetry, and combustion calorimetry) and computational studies. The CN center dot center dot center dot Cl intermolecular interactions are weaker in 2-chlorobenzonitrile, reflecting a lower enthalpy of sublimation. The two polymorphic forms of 4-chlorobenzonitrile were observed by differential scanning calorimetry and interpreted in terms of the strength of CN center dot center dot center dot Cl intermolecular interactions. The entropic differentiation due to the pseudosymmetry observed in the crystalline packing of 2-chlorobenzonitrile was evaluated. Using adequate working reactions and the respective standard molar enthalpies of formation, in the gaseous phase, the halogen-cyano intramolecular interaction was also evaluated. The theoretically estimated gas-phase enthalpies of formation were calculated using high-level ab initio molecular orbital calculations at the G3MP2B3 and MP2/cc-pVTZ levels of theory. The computed values support very well the experimental results obtained in this work.

Abstract When we talk about society, education and technology, it becomes clear how technology has been the source of the most expressive changes that occurred in the society of the 20th and early 21st centuries' society. Technology has been pointed out as responsible for transforming several significant aspects of social reality to such an extent that some authors argue that we are facing new forms of organization of the economic system and of society, which the educational system should seek to match and accommodate. In this article, we present different perspectives which we believe can be successful in promoting a sustained and projective reflection on the past, the present and the future of the interrelationships in social, educational and technological spheres and the possible effects on science teaching that they entail. The article addresses five topics deemed relevant to substantiate the reflection on the subject under consideration. We first present some thoughts about the information society, the network metaphor and the collective potential. We continue with a focus on technology and its relation with the "schools that learn". We then argue that digital literacy goes far beyond technological competence and stress how school - and its agents - can play a mediating role between the challenges of the Knowledge Society and new generations. In this context of multiple interlinked dependencies, the article ends with reflections on science education, science teaching and scientific literacy in the information society.

Abstract This work investigates the Portuguese scientific production published in journals indexed in SCOPUS and Web of Science under the topic of Information and Communication Technologies (ICT) in the field of education. The main objective is to characterize the methodological approaches with special emphasis given to qualitative research. The articles have been categorized according to their methodological approaches (i.e., theoretical or empirical studies, including documental and non-documental - experimental, quasi-experimental and non-experimental). The abstracts have also been coded according to their main themes and operative verbs. After collecting all the available information, a database was created in a spreadsheet. One researcher read all the abstracts and decided whether the work was to be included or not in the corpus of analysis. After this, a second researcher reviewed the selection. Whenever an abstract did not present all the required information, the researchers tried to find the complete paper. If they failed to find it the record should be kept nonetheless. After the first researcher coded all the items, the second researcher reviewed the coding. When they disagreed, they discussed carefully the pros and cons and then adopted a solution; if the disagreement persisted they were expected to present their arguments to the senior researcher, who would decide the matter, but it has not been necessary to use this solution. Preliminary results reveal that methods are not always accurately described and that most works consist of non-experimental designs. Thus, more coherent and precise description of methods, especially when using qualitative analysis, is required. Given the perceived predominance of non-experimental approaches when studying ICT in the field of education, further studies must offer a comparative analysis of the results obtained with foreign production. Simultaneously, research must address the relationship between qualitative methods and sociological factors such as authors' sex, institutional affiliation and cooperation, and publishing impact factor. The results will hopefully bring relevant insights to the Portuguese scientific community interested in studying Information and Communication Technologies in the field of education.

Abstract Disinfection of swimming pool water is essential to inactivate pathogenic microorganisms. However chlorine based disinfectants, the most commonly used, are known to lead to the formation of disinfection by-products (DBPs), some of which have been associated with adverse health effects. Precursors of DBPs include the organic matter present in the water used to fill the swimming pool, human body fluids and personal care products (PCPs) used by swimmers and bathers. The increased use, in the last years, of PCPs lead to an increased concern about the fate of PCPs in swimming pool waters and potential health risks of formed DBPs. In this study, the chemical transformations of two salicylates, benzyl salicylate (BzS) and phenyl salicylate (PS), incorporated in several PCPs, in chlorinated water were investigated. High-performance liquid chromatography (HPLC) with UV-diode-array detection (HPLC-UV-DAD) was used to follow the reaction kinetics and HPLC with mass spectrometry (HPLC-MS) was used to tentatively identify the major transformation by-products. Under the experimental conditions used in this work both salicylates reacted with chlorine following pseudo-first order kinetics: rate constant k = (0.0038 +/- 0.0002) min(-1) and half-life t(1/2) = (182 +/- 10) min for BzS and rate constant k = (0.0088 +/- 0.0005) min(-1) and half-life t(1/2) = (79 +/- 4) min for PS (mean +/- standard deviation). The reactions of the two salicylates in chlorinated water led to the formation of DBPs that were tentatively identified as mono- and dichloro- substituted compounds. Most probably they result from an electrophilic substitution of one or two hydrogen atoms in the phenolic ring of both salicylates by one or two chlorine atoms.

Abstract The present study seeks to become a positive contribution to the research and development of e-learning systems by conducting an exploratory evaluation of the opinions of the academic community of the University of Porto about various technical and social dimensions present in the conception and deployment of learning management systems, both in the context of supporting face-to-face education and as technical infrastructure to blended and distance learning programmes. A survey by questionnaire was applied to 504 members of the academic community at the university, and it was found that among the participants there is still great scepticism towards e-learning and technologically mediated education, especially among younger students. Participants also considered that learning management systems presenting a plethora of features are not as desirable as systems focused on providing a pleasant and consistent user experience.