Publications

Abstract This work investigates the potential of betaine as a substitute for choline chloride in the formation of polyol-based DES. The solid-liquid equilibrium (SLE) phase diagrams of binary mixtures of betaine with one polyol (ethylene glycol, 1,3-propanediol, glycerol, meso-erythritol, xylitol, or sorbitol) were studied across the entire composition range. Experimental measurements of the phase diagrams were limited by the thermal degradation of betaine and by the boiling points or high viscosities of some polyols. Overall, betaine exhibited negative deviations from ideality, while most polyols displayed near-ideal behaviour. COSMO-RS, a thermodynamic model, satisfactorily predicts these deviations from ideality and the observed phase behaviour. Mixtures of betaine and polyols yielded a narrower liquid-phase window for room-temperature applications than the corresponding choline chloride systems. The cross-association of betaine with polyols is more favourable than its self-association, and stronger interactions between the polyols and betaine than with choline chloride are expected, leading to more negative deviations; thus, the smaller melting temperature depression must result from a higher enthalpy of fusion of betaine than that of choline chloride.

Abstract The biphasic transfer of Eu(NO3)3 by trioctylphosphine oxide (TOPO) diluted in a molecular diluent or as a component of a hydrophobic eutectic solvent (HES) was studied by two-phase isothermal titration calorimetry and complemented by XAS, FTIR, and NMR spectroscopy. In HES, the solvent intermolecular interactions introduce an enthalpic penalty, which is overcompensated by a reduction of the entropic cost of Eu(III) phase transfer, resulting in enhanced metal partitioning.

Abstract Concrete structures require precise temperature and humidity monitoring during curing to ensure optimal strength and to prevent defects such as cracking. A compact optical sensing system was developed using a single fiber that can be embedded directly within the concrete. When paired with a spectral interrogation unit operating in the low-loss single-mode communications band of 1500-1600 nm, the system functions as both a temperature and relative humidity (RH) sensor. Temperature monitoring is achieved using a Fiber Bragg Grating, while humidity sensing is provided by a Fabry-Perot interferometer (FPI) at the fiber tip. The interferometer cavity is formed with a layer of polyvinylpyrrolidone (PVP), an RH-sensitive polymer. The system exhibited a response time of approximately 3 h and operated over a relative humidity range of 50-95% RH and a temperature range of 30-60 degrees C, with normalized free spectral range sensitivities of the FPI up to 35 m(-1)/%RH at high humidity levels. The system was validated using a small-scale 50-day in-concrete test.

Abstract Introduction Staphylococcus aureus is an important opportunistic pathogen whose ability to form biofilms and acquire multidrug resistance limits the effectiveness of conventional antibiotics. Although some antibiotic combinations have shown promise, their clinical use is limited by pharmacokinetic and pharmacodynamic issues, chemical instability and formulation challenges. Objectives This study aimed to develop novel hybrid molecules combining ciprofloxacin with plant-derived monoterpenoids to improve antibacterial and antibiofilm efficacy against S. aureus strains. Methods Based on preliminary antibiotic-terpenoids combination studies in S. aureus CECT 976, citronellol and geraniol were selected for hybrid synthesis. The minimum inhibitory concentration (MIC) of the hybrids was evaluated in ciprofloxacin-susceptible ( S. aureus CECT 976) and resistant strains ( S. aureus 8093). Furthermore, the antibiofilm efficacy was analysed in the prevention and eradication of pre-established biofilms by quantifying biomass, metabolic activity and culturability. Moreover, their impact on biofilm structure and membrane integrity was investigated using optical coherence tomography, flow cytometry and epifluorescence microscopy, respectively. Furthermore, matrix components were analysed by spectrophotometry and confocal laser scanning microscopy (CLSM). The cytotoxic and haemolytic profile of the hybrids were evaluated using mammalian cells and red blood cells, respectively. Results For the resistant strain (ciprofloxacin MIC > 1024 µg mL−1), the hybrids showed MICs of 16 µg mL−1, indicating a limited shift in activity compared to the susceptible strain (MIC = 8 µg mL−1). For pre-established biofilms of the S. aureus resistant strain, where ciprofloxacin was ineffective, the hybrids reduced up to 40 % of biomass, inhibited 90 % of metabolic activity and reduced culturability by ∼ 2.3 log(CFU cm−2). They also disrupted the biofilm structure, with an average thickness of less than 10 µm in both strains tested. Furthermore, the hybrids caused significant damage to the cell membrane (90 % in the susceptible strain and about 35 % in the resistant strain) and exhibited low toxicity in HepG2 cells. Consistent with confocal observations, alterations in matrix composition were also observed in the presence of the hybrid compounds. Conclusion This study highlights the potential of monoterpenoid-ciprofloxacin hybrids that combine the antibacterial effects of ciprofloxacin with the bioactive properties of monoterpenes, potentially affecting S. aureus biofilms through multiple mechanisms. Copyright © 2026. Published by Elsevier B.V.

Abstract Antimicrobial photodynamic inactivation (aPDI) is a promising strategy for combating chronic wound infections, particularly those involving biofilms. However, its efficacy against Pseudomonas aeruginosa biofilms is limited by poor light penetration and photosensitisers through the biofilm matrix. This study explores, for the first time, the combination of subinhibitory colistin (Col) concentrations with berberine/curcumin (Ber/Cur) and gentamicin (Gen) to enhance aPDI activity against P. aeruginosa biofilms, including a clinical strain from a diabetic foot ulcer. Membrane integrity changes induced by Col were assessed by flow cytometry with propidium iodide. Synergistic concentrations of Ber/Cur-Gen-Col were determined via checkerboard assay. The effects of blue light (420 nm, 30 mW/cm(2), 10 min) on these combinations were evaluated for both biofilm prevention and eradication assays. For established biofilms, one or three irradiation cycles were applied at 24 h intervals, followed by an assessment of regrowth after 48 and 72 h. Biomass, metabolic activity, and culturability were quantified using crystal violet, resazurin, and colony-forming units (CFU). The mode of action was investigated via ROS production, membrane disruption, and biofilm structural changes using fluorometry, microscopy, and optical coherence tomography. Col at subinhibitory concentrations reduced membrane integrity (approximate to 30 %), enhancing Ber/Cur-Gen efficacy. Photoactivated Ber/Cur-Gen-Col inhibited biofilm formation (>90% reduction in biomass and metabolic activity and 6-log reduction in CFU). Against pre-formed biofilms, this combination achieved a 7-log reduction in CFU and a 90% reduction in biomass and metabolic activity. Three irradiation cycles sustained inhibition for up to 72 h. Ber-Gen-Col showed superior performance, highlighting the synergistic potential of subinhibitory Col in enhancing aPDI as a promising strategy for managing persistent wound infections.

Abstract This work presents a combined experimental and computational thermochemical study of 3-hydroxy-2-methyl-gamma-pyrone (maltol, MAL) and 4-hydroxy-6-methyl-alpha-pyrone (triacetic acid lactone, TAL). Pyrones are biomass-derived molecules known as promising platforms to produce high-value chemicals and biofuels, although reliable thermodynamic data for this family of compounds remain scarce. Herein, we report accurate thermophysical and thermochemical properties obtained from calorimetric experiments and high-level quantum chemical calculations, aiming to support future studies on their conversion pathways, including hydrogenation and hydrodeoxygenation.The thermal behavior of MAL and TAL was investigated by differential scanning calorimetry (DSC), while their combustion energies were measured by static bomb calorimetry, enabling the determination of the corresponding enthalpies of formation in the crystalline phase. Phase transition studies were further performed using the Knudsen effusion mass-loss method and the Calvet microcalorimetry technique. From the experimental data, the gas-phase enthalpies of formation were derived. The quantum chemical calculations performed with the G4(MP2) composite method, showed agreement with the experimental data, supporting the reliability of the results. Additionally, some conversion reactions (mainly ring-opening and decarboxylation) of model biomass-derived cyclic compounds were studied.

Abstract <jats:title>Abstract</jats:title> <jats:p>This study examined the impact of the ExperimentaQuímica program on the teaching of chemistry in Portuguese primary education, designed as a continuing professional development initiative centered on experimental methodologies and individualized support. The aim was to understand the extent to which participation in the program fostered changes in teachers’ perceptions, pedagogical practices, and motivation, as well as to identify the design features that supported these transformations. A mixed-methods approach was adopted, involving 16 female teachers at this educational level. Data collection included pre- and post-test questionnaires and semistructured interviews, analyzed through descriptive and inferential statistics and qualitative content analysis using a hybrid deductive–inductive coding strategy. The results revealed significant changes in perceptions of experimental teaching, positive emotions associated with chemistry teaching, the perceived importance of instructional resources and institutional support, and teachers’ self-perceived preparation for chemistry teaching, as well as an increase in enthusiasm for teaching chemistry. Quantitative findings also indicated reduced agreement with traditional gender-related stereotypes associated with chemistry teaching. The interviews confirmed these trends, highlighting improvements in classroom practices, greater teacher motivation, and positive effects on pupils, notably in increased curiosity and engagement. The design of the program proved decisive, with particular emphasis on the value of individualized support and the provision of tailored laboratory kits. Despite limitations related to sample size and intervention duration, the study suggests the potential of continuing professional development initiatives that integrate experimental practices and personalized support. These findings offer relevant contributions to the promotion of early chemistry education and to the international debate on teacher education and scientific literacy.</jats:p>

Abstract The high costs of equipment and maintenance for Chemistry laboratories are a barrier to quality education in this science. However, the emergence of user-friendly and low-cost technological tools helps to mitigate this problem. This paper presents a STEM proposal for exploring distillation collaboratively in a remote laboratory with live data transmission and sharing online. The approach was analyzed by four teachers from Mozambique who, in that context, highlighted the positive potential for knowledge exchange between schools and cultures and the negative lack of technological means in schools for its implementation. They recognize great potential for implementation in higher education, as institutions have better resources. Thus, richer learning experiences can be promoted for all participants.