Publications

Abstract Overexpression of tumor-associated RAC1b has been recently highlighted as one of the most promising targets for therapeutic intervention in colon, breast, lung and pancreatic cancer. RAC1b is a hyperactive variant of the small GTPase RAC1 and has been recently shown to be overexpressed in a subset of papillary thyroid carcinomas associated with unfavorable outcome. Using the K1 PTC derived cell line as an in vitro model, we observed that both RAC1 and RAC1b were able to induce a significant increase on NF-kB and cyclin D1 reporter activity. A clear p65 nuclear localization was found in cells transfected with RAC1b-WT, confirming NF-kB canonical pathway activation. Consistently, we observed a RAC1b-mediated decrease in I kappa B alpha (NF-kB inhibitor) protein levels. Moreover, we show that RAC1b overexpression stimulates G1/S progression and protects thyroid cells against induced apoptosis, the latter through a process involving the NF-kB pathway. Present data support previous findings suggesting an important role for RAC1b in the development of follicular cell-derived thyroid malignancies and point out NF-kB activation as one of the molecular mechanisms associated with the pro-tumorigenic advantage of RAC1b overexpression in thyroid carcinomas.

Abstract This work aims to calculate the carbon footprint of the ICB produced by a Portuguese company and to compare it with other insulation materials available in the market. A Life Cycle Thinking approach and the ISO/TS 14067 (2013) requirements were followed in this work to perform a "cradle-to-gate" life cycle analysis. The inventory analysis mainly uses primary data collected from a Portuguese ICB producing company, complemented with secondary data from commercial life cycle databases and literature concerning respectively, the external transportation of the cork raw-material and the emission factors of electricity and fuel production and use. Results of this study show that ICB has a carbon footprint of 116.229 kg CO2 equivalent per m(3) of ICB. It is the only insulation material present in the market with a negative carbon footprint, which is mainly due to the utilization of cork, a renewable raw material, the proximity of its source to the factory, and the use of biomass for generating the steam needed for its production process. To the authors' knowledge, this is the first study to report the carbon footprint of ICB and to compare it with other building insulation materials.

Abstract The effect of light-absorbing atmospheric particles on climate change has been incorporated into climate models, but the absence of brown carbon (BrC) in these models has been leading to significant differences between model predictions and measured data on radiative forcing. Also, little is known regarding the relationship between optical properties and chemical compositions of BrC. Thus, we have characterized the absorption properties of catechol and known heterogeneous ozonolysis products, with a theoretical approach based on density functional theory (DFT). While catechol presents a weak absorption maximum in the ultraviolet C (UVC) region, other polyaromatic derivatives present an absorption up to 6 times higher, with biphenyl-2,2',3,3'-tetraol, biphenyl-3,3',4,4',5,5'-hexaol, and terphenyl-2',3,3',3 '',4,4 ''-hexaol presenting the strongest absorption. Moreover, these derivatives now absorb in the ultraviolet B (UVB) and ultraviolet A (UVA) regions, which are types of actinic radiation in the ultraviolet (UV) region not filtered by atmosphere (contrary to UVC), with terphenyl molecules presenting the highest absorption maximum. Furthermore, the absorption efficiency of these compounds is potentiated in the condensed phase, such as cloud droplets, rain, fog, and water films, as a result of a higher degree of electron delocalization. This study provides reliable information regarding the absorption properties of BrC generated by catechol, which is essential for the development of accurate models of climate forcing.

Abstract Will it be relevant in preschool the hands-on chemistry activities? It is the beginning of research in kindergarten. With the early exploration of chemistry, we intend to develop positive attitudes to science, promote the development of scientific language and promote motor development. Research, design and implementation of hands-on activities involving educators and children were used. With an action-research methodology, we tried to address the problem and the children's interests, helping them to observe "their"world. Despite the long way to go, there are benefits executing it.

Abstract In this work, homogeneous and compact thin film deposition using physical vapor methodology is described for a series of inorganic perovskite precursors: lead chloride (PbCl2), lead bromide (PbBr2), and lead iodide (PbI2). The thermal characterization and volatility of all these compounds were obtained: due to enthalpic and entropic contributions, the volatility, crucial for understanding the phase equilibria and thin film growth, of the solid and liquid phases of lead halides increases with the size of the halogen. The morphological analysis by scanning electron microscopy (SEM) reveals that the deposited thin films have high surface coverage and uniformity. Additionally, X-ray diffraction (XRD) evidenced the crystallinity of the prepared films on different surfaces. According to UV-vis spectroscopy, thin films of PbI2 exhibit good optical properties with a band gap energy of 2.3 eV.

Abstract The synthesis and reactivity of 2-[(1E,3E)-4-arylbuta1,3-dien-1-yl]-4H-chromen-4-ones as dienes in Diels-Alder (DA) reactions with several electron-poor and electron-rich dienophiles under microwave irradiation was studied. The optimized reaction conditions were achieved with N-methylmaleimide as the dienophile and Sc(OTf)3 (OTf = triflate) as a Lewis acid under microwave-assisted and solvent-free conditions. The Lewis acid improved the reaction yields as it prevented the adducts obtained from undergoing a second DA reaction; thus, the for-mation of a bisadduct was avoided. The alpha,beta,gamma,delta-diene of the starting chromones was the most reactive, and the computational results confirmed the experimental findings. Theoretical calculations also provided a rationale for the unexpected lack of reactivity shown by some dienophiles. The adducts prepared were dehydrogenated with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); however, the aza adducts were sensitive to the highly energetic reaction conditions necessary for the aromatization.

Abstract A systematic isobaric vapor-liquid equilibrium (VLE) study of seven binary mixtures of 1-butyl-3-methylimidazolium chloride, [C(4)C(1)im][CI], and methanol, propan-1-ol, propan-2-ol, butan-1-ol, butan2-ol, tert-butanol (2-methylpropan-2-ol), iso-butanol (2-methylpropan-1-ol) and pentan-1-01, was carried out at three different system pressures (0.1, 0.07 and 0.05 MPa). Activity coefficients were estimated from the boiling temperatures of the binary mixtures. soft-SAFT equation of state was used to describe the experimental VLE data and all together, allowed to infer and understand the effect of the alcohol alkyl chain length and structural isomerism on the molecular interactions between the IL and the alcohols.

Abstract Methylation at the C2 position of 1,3-disubstituted imidazolium-based ionic liquids (ILs) is one of the structural features that has gained attention due to its drastic impact on thermophysical and transport properties. Several hypotheses have been proposed to explain this effect but there is still much discrepancy. Aiming for the rationalization of the effects of these structural features on the properties of imidazolium ILs, we present a thermodynamic and computational study of two methylated ILs at the C2 position of imidazolium, [C-1(4) C-2(1) (3)C(1)im][NTf2] and [C-1(3) C-2(1) (3)C(1)im][NTf2]. The phase behaviour (glass transition and vaporization equilibrium) and computational studies of the anion rotation around the cation and ion pair interaction energies for both ILs were explored. The results have shown that C2-methylation has no impact on the enthalpy of vaporization. However, it decreases the entropy of vaporization, which is a consequence of the change in the ion pair dynamics that affects both the liquid and gas phases. In addition, the more hindered dynamics of the ion pair are also reflected in the increase in the glass transition temperature, Tg. The entropic contribution of anion-around-cation rotation in the imidazolium [NTf2] ILs was quantified experimentally by the comparative analysis of the entropy of vaporization, and computationally by the calculation of the entropies of hindered internal rotation. The global results exclude the existence of significant H-bonding in the C2-protonated (non-methylated) ILs and explain the C2-methylation effect in terms of reduced entropy of the ion pair in the liquid and gas phases. In light of these results, the C2-methylation effect is intrinsically entropic and originates from the more hindered anion-around-cation rotation as a consequence of the substitution of the -H with a bulkier -CH3 group.

Abstract The molecular and supramolecular structure and energetics of tetracene and rubrene were investigated by a combined experimental and theoretical study. Accurate equilibrium vapour pressures at various temperatures were measured for both compounds. For rubrene the energetic analysis evidences lower crystal packing efficiency, strong molecular destabilization and confirms the non-planar twisted equilibrium structure in the gas phase. The results also indicate that phenyl internal rotation in rubrene is highly hindered. The intra- and intermolecular interactions in crystal tetracene and rubrene were evaluated by computational methods. The representative stacked dimer of the tetracene...tetracene interaction in rubrene has lower ionization energy than the one modelling the same interaction in tetracene, due to stronger cation...pi interactions in the cation-radical of rubrene. Charge distribution in the cation dimer is symmetrical in rubrene, whereas in tetracene it is largely localized on the C-H center dot center dot center dot pi donor partner of the herringbone dimer. These findings highlight the impact of cation...pi interactions on the semiconducting properties of OSCs.