Publications

Abstract Technologies involving a solvent|surface interface, such as nanotechnology, electrochemistry, and energy storage applications, are actively pursuing ecologically responsible and sustainable development practices. In response to this pressing need, deep eutectic solvents have emerged as a promising solution to bridge the gap between technological requirements and environmental concerns. In this work, we present the results of a molecular dynamics simulation study of the interface between a monocrystalline gold surface and the deep eutectic solvent ethaline, where a molar ratio of 1:2 choline chloride:ethylene glycol was used for ethaline. The simulations covered a range of temperatures from 313 K to 343 K and applied charge values ranging from 0 to +/- 24 mu C cm-2. Several key interfacial properties were thoroughly analyzed, including among others, charge density profiles, radial distribution functions, hydrogen bond close contacts, and molecular orientation. Additionally, we examined how the differential capacitance varied upon the applied potential. Our findings reveal that, at neutral surfaces, all components of the solvent are present in the innermost layer, with ethylene glycol molecules being the most prevalent, followed by choline cations and a residual amount of chloride anions. For lower applied charges, this mixed composition at the boundary layer persists, despite the growing accumulation of ionic species with charges opposite to that of the electrode. As surface polarization increases, unique innermost boundary layers composed exclusively of one of the ionic species and the hydrogen bond donor molecules are observed, forming a multilayer structure, with subsequent layers enriched of paired counterions. Interestingly, even at higher applied charges, choline cations and ethylene glycol molecules tended to orient themselves in a parallel fashion toward the electrodes. Differential capacitance curves exhibited a camel-shaped behavior, suggesting a complex interplay of electrochemical processes at the DES|Au(100) interface. In summary, our study provides valuable insights into the interfacial properties of deep eutectic solvents on gold surfaces and their response to changes in temperature and potential, which are crucial for understanding and optimizing deep eutectic solventbased electrochemical systems.

Abstract The study and characterization of the biophysical properties of membranes and drug-membrane interactions represent a critical step in drug development, as biological membranes act as a barrier that the drug must overcome to reach its active site. Liposomes are widely used in drug delivery to circumvent the poor aqueous solubility of most drugs, improving systemic bioavailability and pharmacokinetics. Further, they can be targeted to deliver to specific disease sites, thus decreasing drug load, and reducing side effects and poor adherence to treatment. To improve drug solubility during liposome preparation, DMSO is the most widely used solvent. This raises concern about the potential effect of DMSO on membranes and leads us to investigate, using DSC and EPR, the influence of DMSO on the behavior of lipid model membranes of DMPC and DPPC. In addition, we tested the influence of DMSO on drug-membrane interaction, using compounds with different hydrophobicity and varying DMSO content, using the same experimental techniques. Overall, it was found that with up to 10% DMSO, changes in the bilayer fluidity or the thermotropic properties of the studied liposomes were not significant, within the experimental uncertainty. For higher concentrations of DMSO, there is a stabilization of both the gel and the rippled gel phases, and increased bilayer fluidity of DMPC and DPPC liposomes leading to an increase in membrane permeability.

Abstract Thin films of ionic liquids (ILs) have gained significant attention due to their unique properties and broad applications. Extensive research has focused on studying the influence of ILs' chemical composition and substrate characteristics on the structure and morphology of IL films at the nano- and mesoscopic scales. This study explores the impact of carbon-coated surfaces on the morphology and wetting behavior of a series of alkylimidazolium-based ILs. Specifically, this work investigates the effect of carbon coating on the morphology and wetting behavior of short-chain ([C(2)C(1)im][NTf2] and [C(2)C(1)im][OTf]) and long-chain ([C(8)C(1)im][NTf2] and [C(8)C(1)im][OTf]) ILs deposited on indium tin oxide (ITO), silver (Ag), and gold (Au) substrates. A reproducible vapor deposition methodology was utilized for the deposition process. High-resolution scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy were used to analyze the morphological and structural characteristics of the substrates and obtained IL films. The experimental data revealed that the IL films deposited on carbon-coated Au substrates showed minor changes in their morphology compared to that of the films deposited on clean Au surfaces. However, the presence of carbon coatings on the ITO and Ag surfaces led to significant morphological alterations in the IL films. Specifically, for short-chain ILs, the carbon film surface induced 2D growth of the IL film, followed by subsequent island growth. In contrast, for long-chain ILs deposited on carbon surfaces, layer-by-layer growth occurred without island formation, resulting in highly uniform and coalesced IL films. The extent of morphological changes observed in the IL films was found to be influenced by two crucial factors: the thickness of the carbon film on the substrate surface and the amount of IL deposition.

Abstract This study investigates the structural and dynamic properties of ternary mixtures composed of NaPF6, ethylene carbonate (EC), and the ionic liquid choline glycine (ChGly), with a focus on their potential as electrolytes for supercapacitors. The combination of NaPF6-EC, known for its high ionic conductivity, with the biodegradable and environmentally friendly ChGly offers a promising approach to enhancing electrolyte performance. Through molecular simulations, we analyze how the inclusion of small concentrations of ChGly affects key properties such as density, cohesive energy, and ion mobility. Our findings demonstrate that the NaPF6-EC-ChGly mixture exhibits a complex network of electrostatic interactions and hydrogen bonding, with the glycine anion significantly influencing the liquid structure. In mixtures with small additions of ChGly, we observed an optimal balance of diffusion and ionic mobility. These results highlight the potential of ChGly as a green additive to conventional electrolytes, paving the way for more sustainable and high-performance energy storage devices.

Abstract The Universidade Junior (U.Jr.) program, initiated by the University of Porto (U.Porto), Portugal, is a comprehensive educational initiative conducted during the summer months, primarily targeting the 10-18 age group. The program aims to promote science, technology, arts, humanities, and sports knowledge among elementary and secondary-level students and to influence their vocational choices and higher education aspirations. The study analyses the relationship between participation in the U.Jr. program and subsequent enrollment in higher education at U.Porto. It utilises data collected from 2006 to 2022, comparing U.Jr. participants with students who enrolled as freshmen at U.Porto. A Pearson correlation coefficient was applied to establish the connection between these datasets. Data analysis reveals a significant positive relationship between participation in U.Jr. and the choice of U.Porto for higher education. The study shows that 22 out of 100 first-year students at U.Porto in 2021 had previously attended U.Jr. Moreover, the geographical provenance of participants and U.Porto first-year students showed a robust correlation. The findings suggest that U.Jr. has a substantial impact on attracting students to U.Porto and influencing their academic choices. The program's diverse activities, coupled with its inclusive approach, have been instrumental in increasing the university's attractiveness and helping mitigate the country's low higher education rates. The study underscores the importance of such initiatives in shaping students' educational trajectories and choices for higher education.

Abstract <jats:p>In this workshop, we explored a research example on the field of utopian studies and, within it, feminist criticism to illustrate text analysis with R language using metadata from the Lyman Tower Sargent Bibliography. Participants were introduced to the research topic, the R Studio environment, and guided through the iterative process of text analysis (word frequency and network analysis) with the Quanteda library. We aimed to show that visualizations are, more than results, part of a process that triggers new, more complex research questions</jats:p>

Abstract The present work is focused on determining the enthalpy of formation of several derivatives of amino-1,2,4-triazoles. Experimentally, the enthalpies of formation of the crystalline phase and the enthalpies of sublimation of 3-amino- and 3,5-diamino-1H-1,2,4-triazole were derived, respectively, from static-bomb combustion calorimetry and Calvet microcalorimetry or Knudsen effusion measurements. For 4-amino-4H-1,2,4-triazole, only the enthalpy of sublimation was measured. Gas-phase standard molar enthalpies of formation were also estimated using theoretical calculations performed with the G3(MP2) composite approach. The very good agreement of these estimates with the experimental results, support the extension of this study to the estimate of this property for the remaining compounds not studied experimentally. The results obtained are interpreted in terms of structural contributions.