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- Aplicação de técnicas físico-químicas para a indicação de potencial fraude em mel proveniente de países terceirosPublication . Silva, Bianca Nevado da; Melo, Pedro Miguel Canavilhas; Ferreira, Marília Catarina Leal FazeresO mel é o produto apícola com maior importância comercial e o seu consumo sofreu um aumento global decorrente do aumento da população mundial, da preferência dos consumidores por produtos naturais e saudáveis, e das suas propriedades terapêuticas. A União Europeia é apenas 63% autossuficiente na produção do mel, o que implica a necessidade de realizar importação de países terceiros. O seu alto valor comercial torna o produto vulnerável à prática de fraude, que cada vez são mais inovadoras e variadas, sendo difícil a sua identificação. O objetivo do presente estudo foi a aplicação de métodos físico-químicos de execução rápida e simples que permitam a identificação de possíveis fraudes em méis importados para a União Europeia, proveniente de países terceiros, chegados ao Posto de Controlo Fronteiriço de Lisboa entre novembro de 2023 e junho de 2024. Foram recolhidas 31 amostras de mel de 7 países diferentes (Argentina, Brasil, China, Cuba, El Salvador, Índia e México) nas quais foram determinadas 5 análises: determinação do pH e acidez livre e reação de Fiehe, reação de Lund e reação de Lugol. Obtiveram-se resultados não conformes, na reação de Lugol - 3 amostras (2 do México e 1 de El Salvador) reagiram à solução de Lugol sugerindo a adição de amido ao produto, e na reação de Lund - 21 amostras (20 da China e 1 da Índia) não formaram a quantidade de precipitado no intervalo de 0,6 a 3 ml que era suposto num mel puro, o que sugere perda das substâncias albuminoides durante processamento do mel ou presença de mel artificial ou diluído. Além disso, nas análises realizadas aos méis provenientes da China observaram-se resultados semelhantes ao do xarope de açúcar invertido o qual foi utilizado como controlo positivo ao longo do estudo. Portanto, este estudo mostra a importância da realização de controlos no mel importado e que essas análises podem ser úteis para verificar uma suspeita inicial de adulteração do mel. As análises por si só, não determinam a existência de uma fraude, mas sugerem a sua possível presença, o que suporta o posterior encaminhamento dessas amostras para laboratórios onde se realizem análises mais específicas
- New synthetic strategies and structural optimization of the sugar moiety from a selective butyrylcholinesterase inhibitorPublication . Cachatra, Vasco; Rauter, Amélia PilarThis PhD thesis focused on the synthesis and development of new synthetic strategies towards carbohydrate-based compounds with potential relevance for biological applications. Firstly, the development of a new synthetic methodology to prepare bicyclic sugar moieties bearing a fused furan ring was achieved. This strategy relies on a key Wittig reaction to afford the branched chain at position 3 of the sugar moiety with the required stereochemistry. The regio- and stereo-control was possible through optimization of the reaction conditions, as well as careful construction of the substrate. The presence of a bulky 2-O-pivaloyl group and the use of chloroform as solvent, led to the required (3E)-alkene by reaction of the 3-ulose with [(ethoxycarbonyl)methylene]triphenylphosphorane, while a 2-O-benzoyl protection afforded the corresponding (3Z)-alkene. When using acetonitrile as the reaction solvent, a (2Z)-alkene was formed regardless of the protecting group chosen. This domino reaction occurs through a keto-enol tautomerization, followed by an intramolecular migration of the acyl group at position 2 to position 3, and formation of the corresponding 2-ulose, which finally reacts with the phosphorane to afford the corresponding (2Z)-alkene. These results were significant towards the construction of bicyclic sugar moieties bearing a fused furan ring, present in several biological important compounds, such as the miharamycins sugar moiety as well as a selective butyrylcholinesterase inhibitor. A library of purine nucleosides derived from a previously known selective butyrylcholinesterase inhibitor, the α-anomer of a fully benzylated sugar moiety N7 linked to a 2-acetamidopurine, was also investigated. Although this compound was a strong candidate for drug development, it presented a few pharmacokinetic problems, such as its water solubility and a high molecular weight, due to the high number of benzyl protection groups in the sugar moiety. With the goal of reducing the overall molecular weight, different patterns of protection of the sugar moiety were devised to access the significant positions for the displayed activity. Since an ether protection was necessary as previous studies showed no activity for ester protected sugar moieties, the smaller methyl group was chosen. A strategy was devised to regioselectively protect the different positions of the gluco sugar core by decreasing the number of benzyl groups present in the final compound, until a per-methylated glycosyl donor was synthesized. The presence of a benzyl group at positions 2 and 3 led to a slight decrease of the βN7 yield when compared to the fully benzylated purine nucleoside. When these positions were protected with a methyl group, selectivity towards the βN9 isomer was observed as no αN7 was detected and the βN7 yield was significantly decreased from ≈ 25 % to ≈ 9 %. Biological assays from the synthesized nucleosides, with both acetylcholinesterase and butyrylcholinesterase, showed a significant decrease in the activity of these compounds when compared to the fully benzylated derivative, and the most active compound was 2,3-di-O-benzyl-4,6-di-O-methyl αN7 purine nucleoside, although it showed no selectivity towards butyrylcholinesterase (Kia = 12 μM for AChE, Kia = 83 μM for BuChE). As displayed by these and the previous results, the αN7 isomer seems to favor activity towards cholinesterases. Although this isomer gives the best results, the reaction conditions did not favor the formation of this compound as it was obtained in yields lower than 10 %. The next step was to investigate reaction conditions to improve the αN7 yield. For this, changing the starting material with different leaving groups at the anomeric position as well as different Lewis acid activation in the N-glycosylation were tested. These changes did not present significant improvements, so the reaction was tested at different temperatures, where an increase in the αN7 yield was observed when the reaction was carried out at room temperature when compared to the previously reported temperature of 65 °C. A new analogue of the lead compound was synthesized to perform biodistribution in vivo studies. A 6-bromo purine nucleoside was obtained to undergo a SN2 reaction with a radioiodinated reagent to afford a radioactive labelled compound. This compound was then injected into healthy CD1 mice and results were measured at 2- and 60- min post-injection. The low brain uptake (0.36 % and 0.10 % at 2- and 60- min respectively) suggests that only a low fraction of the radioiodinated compound crosses the BBB. These results encouraged the docking studies of the active site of BuChE with the lead compound. Key interactions were identified with the acetamido group of the purine and the benzyl group from position 2. Since different protecting groups showed lower activity, deoxygenation was attempted at selected positions of the sugar moiety. A regioselective synthetic strategy was then developed towards 4 different deoxygenated sugar moieties. Results showed that removing the benzyloxy group at position 6 or using the corresponding lyxo-pentopyranoside still maintained selective inhibition of butyrylcholinesterase. The most active compounds were also tested for their cytotoxicity and showed low cytotoxicity at the active concentrations.
- A guerra interna em Aragão e a diplomacia com Portugal no século XV (1441 – 1476)Publication . Moysés, Beatriz Fonseca; Araújo, Julieta Maria Aires de AlmeidaNeste trabalho estudamos a complexa rede diplomática entre a Coroa de Aragão e o reino de Portugal para o período entre 1441 e 1476, em que as relações externas entre os dois reinos foram marcadas por uma busca pela paz e pela manutenção da estabilidade de forças no interior da Península Ibérica. Para isto, fez-necessário analisar o contexto político, diplomático e económico das duas entidades, como eles se influenciaram mutuamente, de que maneiras estes cenários moldaram a linha política dos governantes portugueses e aragoneses e, ainda, perceber as vicissitudes das inter-relações destes dois reinos para com o vizinho castelhano em meio a um processo vivo e contínuo que visava o alcance do “equilíbrio peninsular”. A vertente mais importante desta análise, entretanto, compete ao estudo dos vínculos diplomáticos entre as duas coroas durante as décadas de conflitos internos e guerra civil nos territórios sob o jugo de D. João II de Aragão e Navarra e de que maneira estes eventos singulares, inicialmente restritos à esta zona oriental, afetaram o ocidente peninsular.
- La opacidad como potencia: una investigación cinematográfica a partir de 918 gauPublication . Santesteban Pérez, María Aranzazu; Macedo, Susana de Sousa Dias de; Longoni, AnaO trabalho que se segue é o resultado de uma investigação prático-teórica que se debruça sobre uma experiência pessoal e colectiva no quadro do chamado “conflito político basco”. Na base deste trabalho de investigação está a análise crítica das formas narrativas das subjectividades militantes que, tradicionalmente, constituíram formas popularizadas de representação da pessoa militante na dicotomia narrativa de herói vs. traidor. Com o objetivo de mostrar outras formas de articulação da experiência militante que escapam a esta lógica binária, analisa-se, por um lado, o processo de realização do filme 918 gau (Arantza Santesteban, 2021) como uma espécie de narrativa cinematográfica enquadrada na procura de lugares de enunciação política sensíveis e representativos dos estados de vulnerabilidade dos sujeitos militantes. O objetivo desta análise é alargar a representação da experiência militante a partir da ideia de opacidade (Glissant, 2017; Butler, 2016; Wark, 2021; Soto Calderón, 2023) como possibilidade de leitura dos sujeitos politizados a partir de uma perspetiva de não-transparência. Por último, analisam-se dois estudos de caso no âmbito das produções culturais bascas da época contemporânea, aprofundando a figura de María Dolores González Katarain, Yoyes, assassinada pela ETA sob a acusação de traição, bem como a análise da canção “Itziarren semea” do dueto basco Pantxoa eta Peio, como exemplo de modelação da ideia de heroísmo no âmbito do conflito político basco. Como epílogo da investigação, propõe-se uma reflexão final sobre o peso dos memoriais revolucionários do século XX nos imaginários políticos actuais e a necessidade de estabelecer outras representações do político, reivindicando a possibilidade e o direito à opacidade
- From the collection to the digital stage: creative processes based on the Museu Nacional do Teatro e da Dança collectionPublication . Augusto, MicheleThis article outlines the process of integrating theoretical and practical research in the performing arts, with a specific focus on costume design. It aims to illustrate instances where creative action is combined with qualitative research. This is achieved through the development of costume designs using digital tools and iconographic data from the historic costume design collection at the Museu Nacional do Teatro e da Dança (MNTD) of Portugal. The practice-based research method involves creating variations of shapes or digital collages on bodies, utilizing the visual and textual documents from the museum’s archives, along with technological resources for image editing and artificial intelligence generators for creative composition. The goal is to produce diverse forms from the same original design information, thus generating a range of options for new costume creations. This research experimentation seeks to analyze how identical parameters can yield new results derived from scenic memory data without simply replicating them. The outcomes include the presentation of elements combined into new formal models for the same character or serving as inspiration for another character with a similar symbolic or epic foundation. Furthermore, the research aspires to foster future creative processes that utilize the collections as primary sources. It aims to promote exhibitions that blend these sources with new montages and emphasize the various stages of the creation process. This approach aims to highlight the importance of scene design elements and the overall structure involved in crafting a character’s costume, including both formal aspects and associated symbols.