Publications

Abstract The purpose of this research was to determine the energetic and reactivity properties of diphenylamine and 9,10-dihydroacridine using computational methodologies. The equilibrium geometries in the gaseous phase of the studied compounds were analysed in detail and the structural effects on the aforementioned properties were assessed. The values of the gas-phase standard molar enthalpies of formation of diphenylamine (217.7 +/- 1.8) kJ.mol(-1) and 9,10-dihydroacridine (198.7 +/- 4.4) kJ.mol(-1) were estimated by hypothetical gas-phase reactions using the G3(MP2)//B3LYP composite method. These data were compared with the ones available in the literature, including the gas-phase enthalpy of formation of 9,10-dihydroacridine derived from the assumption of comparability of the enthalpies of hydrogenation in the liquid and gas phases. Other gas-phase thermodynamic properties, namely the bond dissociation enthalpies (NAH and CAH) and the gas-phase acidities were also determined. The electrostatic potential surfaces and the frontier molecular orbitals were determined for both compounds, allowing us to infer about its reactivity. Other derived properties include the HOMO-LUMO energy gap and the ionization potential. (C) 2017 Elsevier Ltd.

Abstract The possibility to preserve perspectives of reality with spontaneous creations allowed by the web tools that now empower common users with content production skills highlights the numerous opportunities for the present and future of cultural identity maintenance. Our research approaches digital storytelling during intergenerational dynamics as a stage for a participatory contribution to the maintenance of cultural identity. With an ethnographic approach and with partnerships with existing senior movements, we seek to (a) understand the storytelling processes during intergenerational dynamics, (b) develop a framework for the participative creation of narratives in the context of intergenerational cultural identity maintenance, (c) support the participatory maintenance of cultural identity through a set of workshops for intergenerational storytelling, (d) understand the challenges and opportunities promoted by digital affinity spaces for the maintenance of cultural identity. Our contribution proposes to develop the understanding of the role that interactive narratives can have in the context of cultural identity maintenance, by developing new usage strategies to enhance cultural mediation through social and ubiquitous storytelling strategies.

Abstract In an increasingly aged society, with unmeasurable cultural richness kept by its elder elements for their vast life experience, it is urgent to preserve this cultural knowledge before it disappears. The capacity of the computational space to accommodate a virtualization of reality is evident, alongside with the possibility to preserve perspectives of reality with spontaneous and very easy to sort creations thanks to the web tools that now support content production by any common user. Despite all the relevant problematics brought by this context where the common user is simultaneously consumer and producer of information, the opportunities for the present and future of cultural identity maintenance are numerous. This paper approaches the idea of supporting the participatory maintenance of cultural identity through intergenerational storytelling and the dynamization of digital affinity spaces. Our contribution aims to grow the understanding of the role that interactive narratives can have in the real world and in the specific context of cultural identity maintenance, by developing new usage strategies to enhance cultural mediation with the tools we have available and with the help of social, ubiquitous and mobile storytelling strategies.

Abstract In the present study, the effects of two important oxidizing atmospheric pollutants (O-3 and NO2) on the allergenic properties and chemical composition of Platanus x acerifolia pollen were studied. Pollen samples were subjected to O-3 and/or NO2 under in vitro conditions for 6 h at atmospheric concentration levels (O-3: 0.061 ppm; NO2; 0.025 ppm and the mixture of O-3 and NO2: 0.060 and 0.031 ppm respectively). Immunoblotting (using Pla a 1 and Pla a 2 antibodies), infrared and X-ray photoelectron spectroscopy techniques were used. Immunochemical analysis showed that pollen allergenidty changes were different according to the pollutant tested (gas or mixture of gasses) and that the same pollutant gas may interact in a different manner with each specific allergen. The spectroscopy results showed modifications in the FTIR spectral features of bands assigned to proteins, lipids, and polysaccharides of the pollen exposed to the pollutants, as well as in the XPS spectra high-resolution components C 1s, N 1s, and O 1s. This indicates that while airborne, the pollen wall suffers further modifications of its components induced by air pollution, which can compromise the pollen function.

Abstract The bioluminescent reaction of the "sea firefly" Cypridina hilgendorfii is a prototypical system for marine bioluminescence, as its substrate possesses an imidazopyrazinone core that is a common link among organisms of eight phyla. The elucidation of the mechanism behind Cypridina bioluminescence is essential for future applications in bioimaging, biomedicine, and bioanalysis. In this study we have investigated the key step of chemiexcitation with a combined experimental and theoretical approach. The obtained results indicate that neutral dioxetanone is responsible for efficient chemiexcitation, as the thermolysis of this species gives access to a long region of the potential energy surface (PES), where the ground and excited singlet states are degenerated. Contrary to expected, neither chemically induced electron exchange luminescence (CIEEL) nor charge transfer-initiated luminescence (CTIL) can be used to explain imidazopyrazinonebased bioluminescence, as there is no clear relationship between electron (ET)/charge (CT) transfer (occurring between the electron-rich moiety and dioxetanone) and chemiexcitation. Attractive electrostatic interactions between the CO2 and oxyluciferin moieties allow neutral dioxetanone to spend time in the PES region of degeneracy, while repulsive interactions for anionic dioxetanone lead to a quicker CO2 detachment.

Abstract Chemi-/bioluminescence are phenomena in which chemical energy is converted into electronically excited singlet states, which decay with light emission. Given this feature, along with high quantum yields and other beneficial characteristics, these systems have gained numerous applications in bioanalysis, in biomedicine, and in the pharmaceutical field. Singlet chemiexcitation ismade possible by the formation of cyclic peroxides (as dioxetanones) as thermolysis provides a route for a ground state reaction to produce singlet excited states. However, such thermolysis can also lead to the formation of triplet states. While triplet states are not desired in the typical applications of chemi-/bioluminescence, the efficient production of such states can open the door for the use of these systems as sensitizers in photocatalysis and triplet- triplet annihilation, among other fields. Thus, the goal of this study is to assess the effect of heavy atom addition on the thermolysis and triplet chemiexcitation of a model dioxetanone. Monobromination does not affect the thermolysis reaction but can improve the efficiency of intersystem crossing, depending on the position of monobromination. Addition of bromine atoms to the triplet state reaction product has little effect on its properties, except on its electron affinity, in which monobromination can increase between 3.1 and 8.8 kcal mol(-1).

Abstract An experimental and computational study of the thermochemical and structural properties of ethylenethiourea (ETU) has been carried out. The enthalpies of combustion and sublimation, measured respectively by rotating-bomb combustion calorimetry and Calvet microcalorimetry, yielded the gas-phase enthalpy of formation of ETU at T = 298.15 K. This latter parameter was also derived from high-level molecular orbital calculations at the G3(MP2)//B3LYP level of theory, leading to a value in excellent agreement with the one obtained from experimental data. With the purpose of evaluating the influence of the ring size in the enthalpy of formation of cyclic N,N'-thiourea derivatives, the calculation of the enthalpy of formation of N,N'-trimethylenethiourea (MTU) was performed using the G3-(MP2)//B3LYP approach. The effects of substituents (carbonyl and thiocarbonyl) on the molecular stability of several N-alkyl (cyclic) ureas/thioureas were also studied.

Abstract This paper reports an experimental and theoretical study about the energetic and structural characteristics of the 2-mercaptobenzimidazole (MBI) tautomeric forms (thione and thiol). The standard (pA degrees A = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, in the gaseous phase, for MBI was derived from its enthalpies of combustion and sublimation, obtained by rotating-bomb calorimetry and by the Knudsen effusion technique, respectively. The results are compared with the corresponding data for MBI thione/thiol tautomers calculated by the G3(MP2)//B3LYP approach that suggest the thione form as the preferred form of MBI in gaseous phase. Computationally, the molecular structures of both tautomers were established and the geometrical parameters were determined at the B3LYP/6-31G(d) level of theory. In addiction, the G3(MP2)//B3LYP tautomerization energy at 0 K for thione/thiol forms of MBI was calculated and also evidences that the tautomeric equilibrium favours the thione tautomer. The standard Gibbs energy of formation in crystalline and gaseous phases was also derived, allowing an analysis of the thermodynamic stability of MBI in comparison with other related compounds.

Abstract How can a work of art give us clues about scientific aspects? How can chemistry help a painter enhance his creativity and, above all, preserve the original characteristics of his work? Does an artist require scientific knowledge to innovate or, at least, not to be faked? Other symbiotic fields between art and science are: tattoos, as body art with physical and chemical consequences; pigments, as basic materials with interesting historiographical preparations; spectroscopy diagnosis, as very broad and thorough method of analysis (but also specific and non-intrusive); biosensors, as one of the applications of new pigments. Note also the interconnection between the several possible paths of science and art, which reflect new challenges with enormous potential investigated through a literature review and the application as a case study in an educational inquiry module.

Abstract The disinfection-induced and photo-induced degradation of the UV filter 3-methylbutyl-(2E)-3-(4-methoxyphenyl)-acrylate (IMC) is investigated. High performance liquid chromatography was used to follow the degradation reactions, determine kinetic features and also the influence of external variables on degradation [pH; temperature; chlorine concentration; dissolved organic matter (DOM) concentration]. Liquid chromatography preceded by solid-phase extraction, was used for the determination of by-products. IMC was found to rapidly and substantially degrade in aqueous solution, when in exposure to active chlorine, displaying a pseudo second-order degradation rate constant of 0.042 +/- 0.001 L mol(-1) s(-1), and a half-life period of 23.8 +/- 0.6 s. Contact with aqueous active chlorine proved to yield merely the dichlorinated form of IMC, as the prominent disinfection by-product. The assessment of influence of external variables on degradation, was insured by a Box-Behnken experimental design formulation approach, with factorial analysis. In this regard, data shows that temperature plays a decisive factor in the reaction rate, without DOM in solution, leading to decreasing degradation rates as the temperature increases. With DOM in solution, pH and DOM proved to be the most influential variables on IMC degradation. Regarding the photo-degradation study, results have shown that IMC remained quite stable in aqueous solution when exposed to artificial solar radiation, with a rate constant of 0.00073 +/- 0.00002 min(-1) and a half-life period of 938.5 +/- 31.1 min. This work addresses yet another filter that has never been studied, and hopes to provide clarification on its environmental fate and behaviour when in the aqueous environmental compartments.