Publications

Abstract A review of arts and design undergraduate programmes offered by Portuguese public higher education institutions found out that 50 out of the 105 programmes include at least one unit concerning computer programming in their curricula. A preliminary study partially based on the Unified Theory of Acceptance and Use of Technology (UTAUT), conducted through an online survey, sought to find out how lecturers in those programmes regard the subject of computer programming. A sample of 68 educators participated, split between 43 that reported no knowledge of computer programming and 25 that reported programming proficiency, 14 of which were engaged teaching the subject. A noticeable gender discrepancy was found concerning proficiency, raising the question of whether there's a relation to the anxieties of female students regarding programming found in a related study. Commenting on the relevance of the subject, some educators stressed that coding is both a fundamental problem-solving tool and a means to teach logical thinking, while others highlighted the creative potential of programming. Given the push to demystify computer programming, institutions can be encouraged to reduce the gender imbalance in the programming competency of educators. More research concerning educators' attitudes towards programming is welcome, both through practice characterization case-studies and through a deeper understanding of technology acceptance models applied in higher arts and design education.

Abstract An energetic study of 5-fluoro-2-methylbenzoxazole (FMBO) and of 5-fluoro-2-methylbenzothiazole (FMBT), in condensed and gaseous states, has been performed using calorimetric techniques and computational calculations. The standard (p degrees = 0.1 MPa) molar enthalpies of formation of FMBO and FMBT, in the liquid phase, at T = 298.15 K, were derived from the corresponding standard molar energies of combustion, measured by rotating-bomb combustion calorimetry. At T = 298.15 K, the standard (p degrees = 0.1 MPa) molar enthalpy of vaporization, for each compound, was determined, by a direct method, using the vacuum drop microcalorimetric technique. For each compound, from this last value and from the enthalpy of formation of the liquid compounds, the corresponding standard (p degrees = 0.1 MPa) enthalpy of formation in the gaseous phase has been calculated. Additionally, the gas-phase standard molar enthalpies of formation of these two compounds were estimated computationally at the G3(MP2)//B3LYP level of theory, as well as their gas-phase basicities and proton affinities. (C) 2018 Elsevier Ltd.

Abstract The energetic study of 2-methylnaphtho[1,2-d] oxazole (MN12O), 2-methylnaphtho-[2,3-d] oxazole (MN23O) and 2-methylnaphtho[1,2-d] thiazole (MN12T) has been performed experimental and computationally. The enthalpies of combustion and sublimation/vaporization of these compounds were determined, respectively, from static or rotating bomb combustion calorimetry and high temperature Calvet microcalorimetry and/or the Knudsen-effusion studies. These experimental data allow derivation of the corresponding gas-phase standard molar enthalpies of formation of the three compounds. Additionally, we have obtained the gas-phase standard molar enthalpies of formation of these three compounds, as well of the 2-methylnaphtho[2,3-d] thiazole (MN23T), through high level ab initio calculations, at the G3(MP2)//B3LYP and DLPNO-CCSD(T)/cc-pVTZ levels of theory. The computational study of the molecular structures of the compounds has been carried out. Furthermore, a relationship between the energetic and structural characteristics of these molecules was also evaluated. (C) 2018 Elsevier Ltd.

Abstract Steady-state and time-resolved fluorescence techniques as well as quantum-mechanical calculations were used to study the photophysics and photochemistry of a newly synthesized photoacid. the phenol cyanine picolinium salt. We found that the nonradiative rate constant k(nr) of the excited protonated form of the photoacid is larger than that of the excited-state proton transfer (ESPT) to the solvent, k(ESPT). We estimate that the quantum efficiency of the ESPT process is about 0.16. The nonradiative process is explained by a partial trans-cis isomerization reaction, which leads to the formation of a "dark" excited state that can cross to the ground state by nonadiabatic coupling. Moreover, the ESPT process is coupled to the photo-isomerization reaction, as this latter reaction enhances the photoacidity of the studied compound, as a result of photoinduced charge transfer. To prevent trans-cis isomerization of the cyanine bridge, we conducted experiments of PCyP adsorbed on cellulose in the presence of water. We found that the steadystate fluorescence intensity increased by about a factor of 50 and the lifetime of the ROH band increased by the same factor. The fluorescence intensity of the RO(-)band with respect to that of the ROH band was the same as in aqueous solution. This explains why inhibiting the photo-isomerization reaction by adsorbing the PCyP on cellulose does not lead to a higher ESPT rate.

Abstract The present work addresses computational research focused on the energetic and structural properties of four isomers monohydroxyxanthone, using the G3(MP2)//B3LYP method, in order to evaluate the influence of the hydroxyl (-OH moiety) functional group on the xanthone molecule. The combination of these computational results with previous experimental data of these compounds enabled the determination of their enthalpies, entropies and Gibbs energies of formation, in the gaseous phase, and consequently to infer about the relative thermodynamic stability of the four isomers. Other issues were also addressed for the hydroxyxanthone isomers, namely the conformational and the tautomeric equilibrium analysis of the optimized molecular structures, the frontier orbitals, and the electrostatic potential energy maps. Complementarily, an energetic study of the intramolecular OH center dot center dot center dot O hydrogen bond for 1-hydroxanthone was also performed.

Abstract This work describes the synthesis, structural and optical properties of Tm3+/Yb-3 doped and Ca2+ co-doped YF3 upconversion phosphor material. The effect of Ca2+ ions co-dopant concentration is varied at 0, 10, 20 and 30 mol% to observe it's effect on YF3:Tm3+/Yb3+ through different characterizations like XRD, XPS, FE-SEM, FTIR, UV-vis and upconversion measurements. Dominant upconversion emission bands are found at 450, 476, 645 and 696 nm emission wavelengths corresponding to the D-1(2)-> F-3(4), (1)G(4)-> H-3(6) (1)G(4)-> F-3(4) and F-3(3)-> H-3(6) transitions within Tm3+ activator center on 976nm excitation. Finally, prepared samples are utilized in temperature sensing application demonstrations with Ca2+ ions co-dopants concentration variations.

Abstract The paper presents geoecological evaluation of the city of Loznica for the purposes of sports and recreational tourism based on quantitative method of diversity, V-Wert Method. Using the GIS tool by the quantitative method, the criteria of natural components (relief, forest, water surface and climate) are evaluated for the analyzed area. In the proposed method, the climate factor was supplemented by the analysis of the bioclimatic index Universal Thermal Climate Index (UTCI). When the evaluation was completed, the final results were obtained based on which the degrees of convenience of different parts of the analyzed area have been presented. Out of the total analyzed surface, which amounts to 705 km(2), favorable surfaces comprise 21 km(2) (2.98%), and very favorable surfaces comprise 33 km(2), i.e. 4.68% of the territory. The largest area consists of conditionally favorable terrains - 33 km(2) (47.23%). Since one of the basic strategic priorities of the City of Loznica is improvement and development of sports and recreational tourism, the aim of this analysis is to emphasize the potential of the mentioned area in terms of general suitability of the terrain for the development of this type of tourism.

Abstract The effect of pH of precursor solution has studied on structural and up/downconversion emission properties of Ho3+/Yb3+ doped Gd2O3 host synthesized through hydrothermal route. Best sample morphology (rod-shaped) is found corresponding to the pH value of pH-9.1 of the precursor solution. Due to the low phonon frequency of Gd2O3 host, intense green upconversion emission around 539, 550nm wavelength is observed from the sample on 980nm diode laser excitation. In down conversion emission mode, bands around 539, 550nm and 653nm are found on 449nm arc lamp excitation. The prepared samples were further studied for cathodoluminescence and the effect of magnetic field on the upconversion emission. The sample has also shown optical bi-stability in upconversion emission when the magnetic field was increased from zero to 1.05x10(4) Oe and then decreased to zero.

Abstract Steady-state and time-resolved fluorescence techniques were employed to study a superphotoacid with a pK(a)* of similar to-7, the chlorobenzoate phenol cyanine picolinium salt (CBCyP) in acetonitrile-water mixtures. We found that the time-resolved fluorescence is bimodal. The amplitude of the short-time component depends on chi(water); the larger chi(water), the greater the amplitude. We found that the excited-state proton transfer (ESPT) rate constant, k(PT), is >= 5 X 10(12) s(-1) in mixtures of chi(water) >= 0.08, whereas in neat water, k(PT), = 6 X 10(12) s(-1). The long-time component has a lifetime of 50 ps at chi(water) = 0.75. We attribute this time component to the CBCyP molecules that are not hydrogen-bonded to H2O clusters. The results suggest that the ESPT rate constant to water in acetonitrile-water mixtures depends only slightly on the water cluster size and structure surrounding the CBCyP molecule. We attribute the independence of the ESPT rate on the average water-cluster size to the large photoacidity of CBCyP. QM TD-DFT calculations found that in the excited-state the RO-(S-1) species that is formed by the ESPT process is more stable than the ROH(S-1) species by -5 kcal/mol when four water molecules accept the proton, and when six water molecules accept the proton, the RO-(S-1) drops to -10 kcal/mol. The calculations show that energy stabilities are kept constant in implicit CH3CN-H2O solvent mixtures of dielectric constant of epsilon >= 45.

Abstract In the present work, we report the standard combustion energies of 2-mercapto-l-methylimidazole, 2-mercapto-5-aminobenzimidazole and 2-mercapto-5-methoxybenzimidazole, obtained experimentally from measurements with a rotatory-bomb combustion calorimeter. With these data, for each one of the three aforementioned compounds, the corresponding standard molar combustion enthalpies and the standard molar enthalpies of formation, in the crystalline phase, are calculated. The enthalpies of sublimation of each compound, obtained experimentally using a Calvet Setaram HT 1000 microcalorimeter, are also reported. Using the values of the enthalpies of formation in the crystalline phase and the enthalpies of sublimation, both at 298.15 K, for each compound, the corresponding standard molar enthalpies of formation in gas phase were calculated. Complementary, the enthalpies of formation in the gaseous phase were derived from theoretical calculations made with Gaussian-n composite methodology with n = 3 and 4. The experimental and computational studies suggest that in gaseous phase, the form more stable of each compound is the thione form. (C) 2018 Elsevier Ltd.