Publications

Abstract This paper focuses on the problematic role of digital tools in STEM activities for Physics teaching. A group of 47 teachers of Physics and Chemistry, from middle and secondary education, attended a continuous professional development training course during the academic year 2019/2020 that aimed to promote the development, adaptation, and implementation of STEM activities, centered on various topics in Physics (sound, electricity, kinetic and potential energy, mass and weight, gravitational pendulum and free fall) in teachers’ practices. Most of the activities already had an integration proposal for digital tools. Results revealed that teachers’ options range from adding specific and unspecific tools to implement STEM activities. In most cases, they only replace other non-digital tools. This work contributes to foster the action and reflection related to teachers’ knowledge and experience to introduce digital tools productively, amplify their options, and explore other related areas.

Abstract The standard (p degrees =0.1 MPa) molar enthalpies of formation of orotic and isoorotic acids, in the crystalline phase, were derived from the respective standard massic energies of combustion measured by static bomb combustion calorimetry, in oxygen, at T = 298.15 K, as -821.7 +/- 1.1 kJ mol(-1) and -838.3 +/- 1.9 kJ mol(-1), respectively. The molecular structure and conformational behaviour of orotic and isoorotic acids were studied by theoretical calculations and the standard gas-phase molar enthalpies of formation were derived using an appropriate set of working reactions. Sublimation enthalpies, at the reference temperature T = 298.15 K, were estimated from difference between crystalline and gaseous enthalpies of formation and from statistically-based interaction indices derived from molecular surface electrostatic potentials.

Abstract Featured Application This is a contribution for enlarging the thermodynamic database of organic compounds and ketone derivatives. These data are very relevant to controlling experimental investigations to produce value-added chemical products from biomass. Moreover, the knowledge from such data can be used in the development of schemes for the prediction of homologous properties of related compounds, in particular, modeling studies for the prediction of bio-oil composition. The energetic study of 6-hydroxy-1-indanone and 7-hydroxy-1-indanone was performed using experimental techniques and computational calculations. The enthalpies of combustion and sublimation of the two compounds were determined and allowed to derive the corresponding gas-phase standard molar enthalpies of formation. For this purpose, static-bomb combustion calorimetry and drop-method Calvet microcalorimetry were the experimental techniques used. Further, the enthalpy of fusion of each compound was obtained from scanning differential calorimetry measurements. Additionally, the gas-phase standard molar enthalpies of formation of these compounds were calculated through high-level ab initio calculations. The computational study of the molecular structures of the indanones was carried out and two possible conformers were observed for 6-hydroxy-1-indanone. Furthermore, the energetic effects associated with the presence of one hydroxyl group as a substituent on the benzenic ring of 1-indanone were also evaluated. Both experimental and theoretical methods show that 7-hydroxy-1-indanone is thermodynamically more stable than the 6-isomer in the gaseous phase and these results provide evidence for the existence of a strong intramolecular H-bond in 7-hydroxy-1-indanone. Finally, the intramolecular proton transfer in 7-hydroxy-1-indanone has been evaluated and as expected, it is not energetically favorable.

Abstract Sunscreens have been employed on daily skin care for centuries. Their role in protecting the skin from sun damage, avoiding accelerated photoaging and even limiting the risk of development of skin cancer is unquestionable. Although several chemical and physical filters are approved as sunscreens for human use, their safety profile is dependent on their concentration in the formulation which governs their acceptance by the regulatory agencies. A strategic delivery of such molecules should provide a UV protection and limit the skin penetration. Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) may offer an alternative approach to achieve a synergistic effect on the UV protection when loaded with sunscreens as particles themselves also have a UV light scattering effect. Besides, the lipid character of SLN and NLC improves the encapsulation of lipophilic compounds, with enhanced loading capacity. Silica nanoparticles have also been employed in sunscreen formulations. Due to the formed sol-gel complexes, which covalently entrap sunscreen molecules, a controlled release is also achieved. In the present work, we have developed a new sunscreen formulation composed of hybrid SLN-Silica particles loaded with octyl methoxycinnamate (Parsol (R) MCX), and their further incorporation into a hydrogel for skin administration. Hybrid SLN-silica particles of 210.0 +/- 3.341 nm of mean size, polydispersity below 0.3, zeta potential of ca. [7] mV, loading capacity of 19.9% and encapsulation efficiency of 98.3% have been produced. Despite the slight negative surface charge, the developed hybrid nanoparticles remained physicochemically stable over the study period. Turbiscan transmission profiles confirmed the colloidal stability of the formulations under stress conditions. The texture profile analysis of Parsol-SLN and Parsol-SLN-Si revealed semi-solid properties (e.g. adhesiveness, hardness, cohesiveness, springiness, gumminess, chewiness, resilience) suitable for topical application, together with the bioadhesiveness in the skin of pig ears. The non-irritation profile of the hybrid nanoparticles before and after dispersion into Carbopol hydrogels was confirmed by HET-CAM test.

Abstract This article sums up three case studies carried out at a Portuguese science center, an elementary school, and a preschool, where storytelling and hands-on activities were combined. These studies produced indicators in line with the idea that appropriate and carefully chosen stories, combined with hands-on activities, may be a useful pedagogical approach to promote the attraction of young students to science and to teach some of its concepts. The hands-on activities, related to prior storytelling, seem to be a good way to involve students through listening, reading, imagining, understanding, making, and explaining, and thus can generate interest in science and scientific research. Furthermore, it is necessary to make a deeper assessment of the impact of those approaches on learning, development of scientific literacy, and the way young students perceive chemistry. © 2020 Societe Francaise de Chimie. All rights reserved.

Abstract An academic library created an online course in information literacy skills in 2007 for engineering students. This chapter reports the evaluation of the course's effectiveness in developing those skills. In the academic year 2015/2016, a case study with a mixed-methods approach was applied to 5th-year students (N=91) enrolled in a course unit for Master Dissertation's preparation in the informatics and computing engineering programme. Students showed high confidence in their information literacy skills. Online assignments' performance was good, but activities revealed quality issues. Performance in the course unit's assignments reveals a poor application of acquired skills. But satisfaction is high: students value independent learning and online access to resources and content. Despite evidence of some positive impact, the course lacks effectiveness due to issues in the course unit's assignments. Needed improvements include a better realignment with students' needs and a redesign with an instructional model to assure the promotion of students' success. © 2021 by IGI Global. All rights reserved.

Abstract In the present work, a detailed thermochemical, experimental and theoretical, study of benzocaine is presented. The enthalpy of formation in crystalline state at T = 298.15 K was obtained from combustion calorimetry experiments [Δ<inf>f</inf>H<inf>m</inf>^°cr=-415.2±1.7kJ∙mol^-1], within an oxygen atmosphere, using a static bomb calorimeter. The phase transition enthalpies (fusion, vaporization, and sublimation) were obtained by different techniques, namely differential scanning calorimetry, Calvet microcalorimetry, thermogravimetry, and the Knudsen effusion method. The results obtained by the different techniques are as follows: Δ<inf>cr</inf>^lH<inf>m</inf>^°298.15 K=21.4±0.1 kJ⋅mol⁻¹; Δ<inf>l</inf>^gH<inf>m</inf>^°298.15 K=84.9±1.0 kJ⋅mol⁻¹; Δ<inf>cr</inf>^gH<inf>m</inf>^°298.15 K=106.8±0.4 kJ⋅mol⁻¹. From the experimental results, the enthalpy of formation of the aforesaid compound, in the gas phase, was calculated at T = 298.15 K as: Δ<inf>f</inf>H<inf>m</inf>^°g=-308.4±1.8kJ∙mol^-1. Theoretical enthalpies were computed using the Gaussian G4 composite method, atomization reactions, and the weighted Boltzmann average method. For the latter, the conformational diversity of the molecular structure of the compound was considered. Using the above data and using a similar approach, the theoretical entropy of benzocaine was computed as well. The experimental and theoretical values obtained were compared and an excellent accordance was found. Using the experimental and theoretical results, Gibbs energy of formation in crystalline and gaseous states of benzocaine, at T = 298.15 K were calculated as: Δ<inf>f</inf>G<inf>m</inf>^°cr=-164.4kJ∙mol^-1 and Δ<inf>f</inf>G<inf>m</inf>^°g=-123.9kJ∙mol^-1, respectively. Finally, the results obtained from the enthalpies of phase change are compared with those previously reported in the literature, in order to propose an exact value for these properties.

Abstract The energy involved in the structural switching of acyl and hydroxyl substituents in the title compounds was evaluated combining experimental and computational studies. Combustion calorimetry and Knudsen effusion techniques were used to determine the enthalpies of formation, in the crystalline state, and of sublimation, respectively. The gas-phase enthalpy of formation of both isomers was derived combining these two experimental data. Concerning the computational study, the G3(MP2)//B3LYP composite method was used to optimize and determine the energy of the isomers in the gaseous state. From a set of hypothetical reactions it has been possible to estimate the gas-phase enthalpy of formation of the title compounds. The good agreement between the experimental and computational gas-phase enthalpies of formation of the 1-acetyl-2-naphthol and 2-acetyl-1-naphthol isomers, provided the confidence for extending the computational study to the 2-acetyl-3-naphthol isomer. The structural rearrangement of the substituents in position 1 and 2 in the naphthalene ring and the energy of the intramolecular hydrogen bond are the factors responsible for the energetic differences exhibited by the isomers. The gas phase tautomeric keto <-> enol equilibria of theo-acetylnaphthol isomers were analyzed using the Boltzmann's distribution.

Abstract Ethnopharmacological use of plant natural extracts has been known since ancient times. The optimization of plant molecule extraction is fundamental in obtaining relevant extraction yields. The main purpose of this study was to understand the role of different extraction techniques (solid-liquid, ultrasound, Soxhlet, and microwave) and solvents (water, methanol, ethanol, acetone, dichloromethane, and hexane) on the antimicrobial and antioxidant activities of extracts from Olea europaea (olive) and Acacia dealbata (mimosa). Crude plant extracts were evaluated for their antimicrobial activity against Staphylococcus aureus and Escherichia coli by the disk diffusion method. The antioxidant capacity of the extracts was determined by ABTS (2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods. In terms of extraction yield, ultrasound extraction and the solvents methanol, acetone (O. europaea) or water (A. dealbata) were found to be the best options. However, ethanol and acetone proved to be the best solvents to extract compounds with antimicrobial activity and antioxidant capacity, respectively (regardless of the extraction method employed). Soxhlet and microwave were the best techniques to extract compounds with antimicrobial activity, whereas any of the tested techniques showed the ability to extract compounds with antioxidant capacity. In most of the cases, both plant extracts (mimosa and olive) were more efficient against S. aureus than E. coli. In the present study, both mimosa and olive leaf crude extracts proved to have antimicrobial and antioxidant activities, increasing the demand of these natural products as a source of compounds with health benefits.