Publications

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 O 2º Encontro de História para a Ciência no Ensino (2EHCE) foi uma organização conjunta da Universidade de Coimbra (UC), Universidade do Porto (UP) e Universidade de Trás-os-Montes e Alto Douro (UTAD) que teve lugar nos dias 26 e 27 de maio de 2017, no Departamento de Química da Universidade de Coimbra, integrando e dando continuidade ao III Colóquio de História da Ciência para o Ensino, na sequência da edição anterior realizado na UC em 2014. O Encontro teve associada uma Ação de Formação intitulada A História da Ciência no Ensino das Ciências, da responsabilidade do Gabinete de Formação da UTAD, creditada para os professores dos grupos 230, 510 e 520. Com o tema História da Ciência no Ensino do Século XXI, o 2EHCE visou juntar investigadores, professores e estudantes interessados na história e no ensino da Biologia, Geologia, Química, Física e Matemática, assim como das Ciências da Educação, Antropologia, Astronomia, Biologia Molecular, Bioquímica, Ecologia, Economia, Engenharias, Farmácia, Medicina, Nanociências, Psicologia, Sociologia, entre outras, num debate multicentrado e multidisciplinar. Para além de trabalhos focados no ensino, educação, didática e divulgação das ciências, o 2EHCE procurou congregar reflexões e estudos de carácter mais geral, disciplinares ou interdisciplinares, de história da cultura, da técnica e da indústria, assim como estudos epistemológicos, historiográficos, biográficos ou prosopográficos. Outros temas relevantes para a história da ciência e para o ensino, como sejam os estudos de género, o ensino das ciências em língua estrangeira e, de forma geral, as várias vertentes das interações entre as ciências, as tecnologias e as humanidades, foram muito bem-vindos para o espaço de diálogo que o 2EHCE procurou criar. No decurso do 2EHCE foram lembradas as memórias da Professora Celeste Gomes (1962-2016), docente do Departamento das Ciências da Terra da UC, que esteve na génese e organização dos encontros anteriores, e do Professor Sebastião Formosinho (1943-2016), docente do Departamento de Química da UC, que pertencia à Comissão Científica do Encontro. Durante os dois dias do 2EHCE foram apresentadas 58 comunicações orais e estiveram presentes 111 participantes oriundos de Portugal, Brasil e Espanha. Por último, gostaríamos de agradecer aos elementos da Comissão Científica, a todos os participantes, bem como às instituições que se associaram e que tornaram possível esta reunião científica.

Abstract Nanotechnology is one of the most innovative scientific research fields, especially with regard to medical applications. The use of nanotechnology in medical applications is called nanomedicine and is based on the application of nanoparticles for diagnosis and treatment of several clinical conditions. In particular, many physicochemically distinct nanomaterials have been tested in the form of nanoparticles for cancer diagnosis and therapy. This new branch of science, in which nanotechnology is used against cancer, has been named nanooncology. Nanooncology uses materials in nanoscale to delineate the tumor margins, to separate cancer cells from healthy cells, to identify micrometastasis, and to determine if the tumor has been completely removed or not. This approach means fewer side effects and less drug use. Nanoparticles also have the potential of site-specific targeting and controlled drug release; thus, a strong dose of drug could be concentrated within a specific area, but with a planned and scheduled release, to ensure maximum effectiveness and patient safety. Although being designed to target specific organs/tissues/cells, nanoparticles may interfere with other organs/tissues, such as liver and blood. Nanoparticles can be engineered to avoid the immune system recognition or to specifically inhibit or enhance the immune responses; they are strange bodies for the immune system and may induce undesirable immunotoxicity. This chapter highlights the benefits of nanotechnology and of nanomedicines for cancer diagnosis and therapy, focusing on the relevant aspects of nanotoxicology.

Abstract The aim of this study was the assessment of the physicochemical stability of D-alpha-tocopherol formulated in medium chain triglyceride nanoemulsions, stabilized with Tween(R)80 and Lipoid(R)S75 as surfactant and co-surfactant, respectively. D-alpha-tocopherol was selected as active ingredient because of its well-recognized interesting anti-oxidant properties (such as radical scavenger) for food and pharmaceutical industries. A series of nanoemulsions of mean droplet size below 90 nm (polydispersity index < 0.15) have been produced by high-pressure homogenization, and their surface electrical charge (zeta potential), pH, surface tension, osmolarity, and rheological behavior, were characterized as a function of the D-alpha-tocopherol loading. In vitro studies in Caco-2 cell lines confirmed the safety profile of the developed nanoemulsions with percentage of cell viability above 90% for all formulations. (C) 2016 The Authors.

Abstract Nanotechnology holds the promise of develop new processes for wastewater treatment. However, it is important to understand what the possible impacts on the environment of NMs. This study joins all the information available about the toxicity and ecotoxicity of NMs to human cell lines and to terrestrial and aquatic biota. Terrestrial species seems more protected, since effects are being recorded for concentrations higher than those that could be expected in the environment. The soil matrix is apparently trapping and filtering NMs. Further studies should focus more on indirect effects in biological communities rather than only on effects at the individual level. Aquatic biota, mainly from freshwater ecosystems, seemed to be at higher risk, since dose effect concentrations recorded were remarkable lower, at least for some NMs. The toxic effects recorded on different culture lines, also give rise to serious concerns regarding the potential effects on human health. However, few data exists about environmental concentrations to support the calculation of risks to ecosystems and humans.

Abstract Current advances in systems biology suggest a new change of paradigm reinforcing the holistic nature of the drug discovery process. According to the principles of systems biology, a simple drug perturbing a network of targets can trigger complex reactions. Therefore, it is possible to connect initial events with final outcomes and consequently prioritize those events, leading to a desired effect. Here, we introduce a new concept, 'Systemic Chemogenomics/Quantitative Structure-Activity Relationship (QSAR)'. To elaborate on the concept, relevant information surrounding it is addressed. The concept is challenged by implementing a systemic QSAR approach for phenotypic virtual screening (VS) of candidate ligands acting as neuroprotective agents in Parkinson's disease (PD). The results support the suitability of the approach for the phenotypic prioritization of drug candidates.

Abstract Neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, threaten the lives of millions of people and the number of affected patients is constantly growing with the increase of the aging population. Small molecule neurotrophic agents represent promising therapeutics for the pharmacological management of neurodegenerative diseases. In this study, a series of caffeic acid amide analogues with variable alkyl chain lengths, including ACAF3 (C3), ACAF4 (C4), ACAF6 (C6), ACAF8 (C8) and ACAF12 (C12) were synthesized and their neurotrophic activity was examined by different methods in PC12 neuronal cells. We found that all caffeic acid amide derivatives significantly increased survival in PC12 neuronal cells in serum-deprived conditions at 25 mu M, as measured by the MU assay. ACAF4, ACAF6 and ACAF8 at 5 mu M also significantly enhanced the effect of nerve growth factor (NGF) in inducing neurite outgrowth, a sign of neuronal differentiation. The neurotrophic effects of amide derivatives did not seem to be mediated by direct activation of tropomyosin receptor kinase A (TrkA) receptor, since K252a, a potent TrkA antagonist, did not block the neuronal survival enhancement effect. Similarly, the active compounds did not activate TrkA as measured by immunoblotting with anti-phosphoTrkA antibody. We also examined the effect of amide derivatives on signaling pathways involved in survival and differentiation by immunoblotting. ACAF4 and ACAF12 induced ERK1/2 phosphorylation in PC12 cells at 5 and 25 mu M, while ACAF12 was also able to significantly increase AKT phosphorylation at 5 and 25 mu M. Molecular docking studies indicated that compared to the parental compound caffeic acid, ACAF12 exhibited higher binding energy with phosphoinositide 3-kinase (PI3K) as a putative molecular target. Based on Lipinski's rule of five, all of the compounds obeyed three molecular descriptors (HBD, HBA and MM) in drug-likeness test. Taken together, these findings show for the first time that caffeic amides possess strong neurotrophic effects exerted via modulation of ERK1/2 and AKT signaling pathways presumably by activation of PI3K and thus represent promising agents for the discovery of neurotrophic compounds for management of neurodegenerative diseases.

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.