ESTiG - Dissertações de Mestrado Alunos
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- Direção de obras na área das instalações elétricas de edificações: desafios e boas práticasPublication . Marinho, Bruno Olavo Pinheiro; Soares, OrlandoAs infraestruturas desempenham um papel essencial no desenvolvimento económico e na qualidade de vida das populações. O crescimento do investimento global neste setor tem conduzido a um aumento significativo do número de projetos e empreendimentos, exigindo técnicos e entidades responsáveis capazes de assegurar a sua conceção, execução e fiscalização. Neste contexto, a direção de obra assume-se como uma função central, garantindo a articulação entre os aspetos técnicos e práticos da construção. O presente relatório resulta do estágio curricular realizado na empresa Bragalux, S.A., no âmbito da obtenção do grau de Mestre em Engenharia Eletrotécnica e de Computadores. O estágio foi desenvolvido no departamento de Edificações, na especialidade de instalações elétricas, acompanhando de forma direta as funções e responsabilidades inerentes à direção de obra. Ao longo do relatório são explorados os regulamentos e legislações que regem tanto as edificações como as instalações elétricas, bem como as principais entidades envolvidas no processo de conceção e execução em Portugal. Para além disso, descrevem-se as diferentes atividades desempenhadas no âmbito da direção de obra, ilustradas com casos práticos e acompanhadas de considerações finais e boas práticas, consolidando o conhecimento adquirido. O trabalho evidencia ainda a relevância do acompanhamento contínuo da obra como ponte entre os aspetos técnicos e a realidade prática da execução, assegurando que os trabalhos decorrem em conformidade com os requisitos regulamentares, contratuais e de planeamento.
- Development of cosmetic functional formulations incorporating hyaluronic acidPublication . Silva, Thaís Rossetto Cordeiro da; Barreiro, Filomena; Echart, Arantzazu Santamaria Echart; Düsman, ElisângelaThe cosmetic industry has been expanding continuously, driven by demand for innovative, sustainable, and high-performance formulations. In this context, this work aimed to develop particles composed of hyaluronic acid (HA) and Collagen type I (Col) to act as Pickering stabilisers in cosmetic emulsions. The particles were prepared using different methods (direct mixing - mix and droping - drop), with the most promising dispersions obtained after high-shear homogenisation: P_17_Mix_Ultra and P_17_Drop_Ultra. These formulations exhibited particle sizes of 12.30 ± 3.73 μm and 2.55 ± 0.08 μm, respectively. Both showed highly negative zeta potentials (–37.73 ± 1.50 mV for the mix and –37.72 ± 0.56 mV for the drop), confirming colloidal stability. Wettability tests demonstrated strong oil affinity, with contact angles of 128.30 ± 1.05° and 137.22 ± 3.20°. The drop method stood out for producing smaller, more homogeneous particles. Pickering emulsions were then prepared using sweet almond oil, Miglyol 812, and olive oil. Olive oil originated the most stable systems, and emulsions with a higher oil fraction (70:30 oil-to-aqueous ratio) presented superior stability compared to those with lower oil content. Analyses of emulsion type, colourimetry, creaming index, droplet size, microscopy, zeta potential, and rheology confirmed the better performance of olive oil-based formulations obtained by the drop method. The formulation E_70_OO_17d (drop method, olive oil, 70:30 ratio) achieved the most promising overall results, with a creaming index of 10% after 30 days, homogeneous droplets, and rheological behaviour exhibiting viscoelastic properties comparable to those of commercial products. In conclusion, HA-Col particles proved to be efficient Pickering stabilisers, enabling the development of stable emulsions. The most promising formulation, E_70_OO_17d, was particularly suitable for moisturising and anti-ageing cosmetic applications, where hyaluronic acid provides hydration and regeneration while Col enhances elasticity and repair.
- Development of functional films based on antimicrobial photodynamic inactivationPublication . Carrasqueiras, Miguel Fernandes; Crugeira, Pedro; Barreiro, FilomenaMicrobial contamination remains a major food safety challenge, requiring innovative and sustainable control strategies beyond traditional thermal or chemical methods. Antimicrobial photodynamic inactivation (aPDI) has emerged as a promising alternative, based on the activation of photosensitizers that induce the formation of reactive oxygen species (ROS) capable of eliminating microbial cells. In this work, κ-carrageenan-based functional films incorporating curcumin solid dispersions at 1% and 5 wt% concentrations, designated CF_1%_1Y and CF_5%_1Y, were evaluated as photoactive systems for food applications. The solid dispersion approach improved the stability, amorphization, and homogeneous distribution of curcumin in the hydrophilic polymeric matrix. The FTIR and DSC analyses confirmed the preservation of the polymer network and the amorphous state of curcumin. The absorption spectrum at 445 nm, characteristic of curcumin, was identified by UV-Vis spectrophotometry. Evaluation of the mechanical properties demonstrated the structural integrity and strength of the CF_5%_1Y film, yielding a tensile modulus of 196.5 ± 15.6 MPa, a tensile strength at break of 3.22 MPa, and a strain at break of 4.03%. In planktonic cells, CF_5%_1Y under LED irradiation (450 ± 10 nm), at an energy density of 100 J/cm², reductions of 99.9% for Escherichia coli and 96.7% for Listeria monocytogenes were achieved, confirming the synergistic action of light, oxygen, and curcumin in ROS generation. Decontamination tests performed on cream cheese and mayonnaise matrices confirmed the antimicrobial properties of aPDI, previously identified in planktonic cells. When using irradiated CF_5%_1Y films, microbial reductions of 98.5% for E. coli and 99.4% for L. monocytogenes were observed in the mayonnaise matrix. In contrast, in cream cheese, reductions reached 91.2% for E. coli and 92.8% for L. monocytogenes. In 15-day preservation tests, samples of mayonnaise and cream cheese with irradiated CF_5%_1Y films maintained the integrity of the food matrices, with constant microbial concentrations of 1.7-1.8 log CFU/g. At the same time, the controls showed increased contamination, reaching approximately 4.3 log CFU/g in mayonnaise and 2.3 log CFU/g in cream cheese. These results demonstrate the effectiveness of functionalization and photoactivity, corroborating the development of stable, efficient, and sustainable films with antimicrobial properties for food decontamination and preservation, offering an eco-friendly path.
- A deep learning system for daily activity recognition in smart home environmentsPublication . Dessanti, Augusto Luvisa; Lima , JoséThis work presents the implementation of a system for daily activity classification using 3D Convolutional Neural Networks (3D CNN) and the Toyota Smarthome Dataset. The system aims to generalize and correctly classify activities, even in the face of data limitations such as high class imbalance, ambient occlusions, and similarities between classes. To overcome these challenges, preprocessing techniques and data augmentation were applied, including spatio-temporal resizing and image enhancement, with the objective of optimizing learning and generalization capabilities of the model. The proposed approach proved to be effective compared to other models on the same dataset, achieving 85.7% accuracy, 0.8568 precision, and 0.8570 recall.
- Greening the grey: application of eco- engineering to coastal and harbour infrastructuresPublication . Monteiro, Maria Luiza Carvalho; Bráz-César, Manuel; Ferreira, Saulo RochaThis research explores the application of nature-based solutions in port infrastructures as a strategy to promote environmental sustainability in traditionally artificialized coastal environments. In a scenario of global warming, rising sea levels and increased frequency of extreme weather events, especially in urbanised coastal areas, the applicability of these solutions in Portugal’s commercial ports was analysed. These approaches are in line with European and global goals for sustainable development and biodiversity conservation, as they help to mitigate the impacts of dredging, restore degraded habitats, favour marine biodiversity and protect coastal areas from overtopping and flooding. The research is based on the concept of greening the grey, derived from eco-engineering, which proposes the incorporation of ecological principles into the hard environment of urban infrastructures. The methodology consisted of selecting six techniques applicable to ports, identified through a review of the Scopus database and the EcoShape website, followed by an analysis of 26 commercial ports in mainland Portugal and the autonomous regions, based on physical, operational and environmental parameters. The results indicate that three of the techniques, including two aimed at promoting biodiversity and one at coastal protection, have demonstrated applicability in at least 19 ports, due to their technical and economic viability. The other techniques, with more specific requirements, were considered viable in a smaller number of ports. Even so, all the ports analysed showed potential for adopting at least two solutions. The research contributes to future studies aimed at the implementation of these techniques by port authorities and encourages the integration of nature-based solutions into rigid port infrastructures.
- Soldadura do aço SAE 1020 com processo MAG: influência do recozimento e otimização pelo método TaguchiPublication . Turone, Renato Augusto do Carmo; Ribeiro, J.E.; Francisco , Júlio César de SouzaO processo de soldadura MIG/MAG é amplamente utilizado na indústria devido à sua alta eficiência na união de materiais por fusão com arco elétrico. A definição adequada dos parâmetros operacionais impacta diretamente na qualidade do cordão de solda. Com o ajuste correto desses parâmetros, é possível reduzir o consumo de material de adição, otimizar propriedades mecânicas e, por consequência, elevar a produtividade do processo. Este estudo teve como finalidade selecionar um conjunto de variáveis de soldadura e otimizá-las por meio da metodologia de Taguchi, além de analisar sua influência com base na Análise de Variância (ANOVA). Foi utilizado um arranjo ortogonal L9, envolvendo três fatores (tensão de soldadura, velocidade de avanço e ângulo da tocha), cada um em três níveis distintos. Após a realização das nove combinações experimentais, foram efetuadas análises macrográficas e ensaios de flexão, tanto para amostras submetidas ao recozimento quanto para aquelas sem tratamento térmico, de modo a determinar características geométricas e mecânicas. A otimização foi conduzida com o auxílio das razões sinal-ruído, enquanto a ANOVA permitiu identificar a relevância de cada parâmetro de entrada sobre os resultados obtidos, como largura, reforço, penetração e limite de resistência à flexão do cordão de solda. Observou-se que a velocidade de soldadura teve maior impacto sobre o reforço nas amostras sem recozimento (33,08%), ao passo que nas recozidas, a tensão foi predominante (53,05%). Em relação à largura, a tensão demonstrou maior influência em ambos os casos, com 36,94% e 34,89% para amostras sem e com recozimento, respectivamente. Para a penetração, o ângulo da tocha foi o fator de maior relevância, contribuindo com 59,47% nas amostras sem recozimento e 48,24% nas recozidas. Quanto à resistência à flexão, a velocidade foi dominante nas amostras não recozidas (27,59%), enquanto o ângulo da tocha prevaleceu nas recozidas (26,54%). As combinações otimizadas encontradas para os diferentes parâmetros foram: para o reforço, 25 , 23,7 V e 400 mm/min nas amostras sem recozimento, e 0 , 24,1 V e 250 mm/min nas recozidas; para a largura, 0 , 24,1 V e 400 mm/min nas não recozidas, e 25 , 23,7 V e 325 mm/min nas recozidas; para a penetração, 0 , 24,1 V e 400 mm/min nas amostras sem recozimento, e 15 , 22,4 V e 325 mm/min nas recozidas; e, por fim, para o limite de resistência à flexão, as melhores condições foram 25 , 23,7 V e 250 mm/min sem recozimento, e 0 , 23,7 V e 250 mm/min com recozimento.
- Retting of natural fibers for the manufacturing of filamentsPublication . Ferreira, Luana Francisca Novais; Rocha, João; Ribeiro, J.E.Nos últimos anos, a necessidade imperiosa de mitigar a dependência de polímeros derivados do petróleo, aliada à crescente exigência por materiais ambientalmente sustentáveis, tem fomentado de forma significativa a investigação no domínio dos compósitos biodegradáveis. Entre os biopolímeros disponíveis, o ácido poliláctico (PLA) evidencia-se pela sua proveniência renovável, biodegradabilidade e propriedades mecânicas superiores face a outros polímeros sustentáveis. Contudo, o PLA apresenta limitações intrínsecas, nomeadamente fragilidade e reduzida resistência ao impacto, características que podem ser atenuadas mediante a incorporação de fibras naturais como elementos de reforço. As fibras lignocelulósicas naturais têm vindo a assumir uma preponderância crescente no setor industrial, devido à sua relação otimizada entre resistência e massa volúmica, elevada biodegradabilidade e impacto ambiental quando comparadas com as fibras sintéticas. Alguns exemplos de fibras naturais muito utilizadas são as do cânhamo e do linho O cânhamo, em particular, distingue-se pela sua robustez estrutural e elevada rigidez, sendo amplamente utilizado nas indústrias automóvel e da construção. O linho, por outro lado, estingue-se pela sua flexibilidade e notável capacidade de absorção a impactos. O presente estudo visa a investigação, caracterização e otimização da produção de fibras naturais de cânhamo, linho e castanha para a formulação de filamentos destinados à manufatura aditiva, com particular foco na impressão tridimensional. Será realizada uma análise holística das propriedades físicas, químicas e mecânicas dos compósitos obtidos, com o intuito de aferir a viabilidade da substituição de reforços convencionais por fibras naturais. Os resultados do trabalho desta tese contribuirão para o desenvolvimento de soluções compósitas inovadoras, sustentáveis e de elevado desempenho, promovendo alternativas tecnologicamente avançadas e ambientalmente responsáveis em setores industriais estratégicos.
- Estrogen removal through adsorption using carbon materials prepared from biomass wastePublication . Exposto, Bruno Marques; Queiroz, A.M.; Ribeiro, António E.; Brito, PauloEndocrine disruptors are class of micropollutants that can influence and deregulate the endocrine system in humans and animals. Endocrine disruptors can consist of natural estrogenic hormones, such as E1 and E2, and synthetic estrogenic hormones, such as EE2, that are not easily removed by conventional treatment processes in water and sewage treatment plants, becoming dangerous emerging pollutants. This work addresses the removal of such compounds from aqueous matrices through adsorption processes onto activated carbon produced from biomass waste. The materials selected were almond shell in natura (ASiN) and cork in natura (CiN). These were activated through carbonization at 550ºC for 1 h, obtaining carbonized almond shell (CAS) and carbonized cork (CC). These materials were characterized by carbonization yield, moisture and ash content, PZC value, quantification of acidic and basic sites and FTIR analysis. For the adsorption assays, the impact of conditions such as adsorbent type, temperature and medium pH was assessed in relation to removal performance. Kinetic and isotherm assays were also performed in batch mode, together with the assessment of the thermodynamic data. The results show that equilibrium time was 16 h for ASiN, 4 h for CAS, 6 h for CiN and 24 h for CC. The adsorption process was regulated through the Elovich model for all adsorbents except for CiN, where the best model was PSO. Moreover, cork-based adsorbents presented higher adsorption capacities and activation through carbonization did not contribute to an increase in estrogen removal. Therefore, CiN was selected as the best material for estrogen removal to the posterior assays. A temperature increase did not affect CiN’s adsorption capacity, and Ea was determined to be 136.15, 80.84 and 146.81 kJ/mol for E2, EE2 and E1, respectively. Moreover, pH change only negatively affects adsorption when in extreme basic media. CiN’s adsorption process has been characterized by the Sheindorf-Rebuhn-Sheintuch multicomponent isotherm for all estrogens, with maximum adsorption capacities of 3.75, 7.23 and 3.82 mg/g achieved for estrogens E2, EE2 and E1, respectively, at 25ºC. Average removal percentage increased with the adsorbent’s dosage until it reached a maximum of 66.1% at 1 g/L. Both the adsorption capacity and removal percentage decreased with the increase in temperature. Thermodynamic data was determined and negative values for ΔGº and ΔHº and positive values for ΔSº were obtained, meaning that adsorption was characterized as spontaneous, exothermic and entropically favourable. It was verified that estrogen adsorption occurred through a combination of chemisorption and physisorption phenomena. Chemisorption occurred mainly through pEDA interactions and hydrogen bridges between estrogen and CiN’s functional groups and aromatic rings, while physisorption occurred mainly through pore filling. pEDA bonding assisted by hydrophobic interactions could be an explanation for the higher adsorption rates verified for EE2 in CiN.
- Green extraction of artemisinin from Artemisia annua L. and evaluation of the antimalarial activityPublication . Corso, Luan Barichello; Martins, Mónia; Pinho, Simão; Ferreira, Olga; Zuber, AndréMalaria remains one of the greatest global public health challenges, affecting millions of people, especially in tropical and subtropical regions. One of the main obstacles to treating the disease is the low water solubility of antimalarial compounds, which compromises their bioavailability. In this work, terpenes are proposed as alternative solvents and pharmaceutical excipients for processing and formulating these drugs, aiming for higher sustainability and safety in line with green chemistry principles. First, the COSMO-RS model was used to investigate approximately 8000 systems that combine solvents from different classes with antimalarial drugs (artemisinin, quinine, quinidine, tetracycline, artemether, dapsone, and pyrimethamine). Focusing on artemisinin and the evaluated terpene candidates, thymol and its mixtures with α-pinene, β-pinene, γ-terpinene, and p-cymene showed the greatest potential, and were selected as solvents to extract artemisinin from the plant Artemisia annua L. Heat extractions with magnetic stirring were performed using a carousel system under the conditions: 50 °C, 600 rpm, 1 hour, and 1:10 solid-liquid ratio. Besides artemisinin (ART), dihydroartemisinic acid (DHAA) was also identified in significant amounts. The extraction yields using conventional solvents were 1.15 mg ART/gplant and 5.53 mg DHAA/gplant for water and 7.11 mg ART/gplant and 9.42 mg DHAA/gplant for ethanol. Higher global yields were obtained using pure terpenes (α-pinene and β-pinene), and all the equimolar thymol mixtures. The highest values were 10.43 mg ART/gplant for the thymol:α-pinene mixture and 11.86 mg DHAA/gplant for α-pinene. These values are consistent with the maximum amount available in the plant (11.2 ± 0.8 mg ART/gplant, 13.4 ± 1.0 mg DHAA/gplant), obtained by performing five consecutive extraction cycles with an Accelerated Solvent Extractor (100 °C, 5 min, 1:10 S/L ratio). A selected set of extracts (water, dichloromethane, ethanol, p-cymene, γ-terpinene, α-pinene, β-pinene) was subject to in vitro antimalarial activity assays against Plasmodium falciparum (strain 3D7-GFP). All extracts obtained with terpenes were proven to be significant inhibitors, with IC50 values ranging from 5.19 nM (γ-terpinene) to 8.17 nM (α-pinene), close to the value of the standard artemisinin (IC50 = 4.20 nM). Terpenes maintained high activity, highlighting them and reinforcing their predictions as a green alternative for the extraction and formulation of antimalarial compounds.
- NR tattoo artPublication . Parise, Nathalya Maria Ferreira dos Reis; Pereira, Ana I.A tatuagem é, segundo Michaelis (2025) a arte e técnica de gravar na pele por meio de pigmentos corantes, por agulhas, uma mensagem ou um desenho indeletável e permanente, cuja motivação para seus cultuadores pode ser uma pessoa, uma data especial ou apenas de ter uma obra de arte viva e atemporal gravada no próprio corpo. Atualmente, pode-se observar cada vez mais pessoas a fazerem tatuagens para se expressarem, tornando as tatuagens mais pessoais e exclusivas. É nesse contexto que entra o NR Tattoo Art, um estúdio especializado no estilo fine line e que o foco é o atendimento exclusivo e diferenciado dos seus clientes, criando desenhos únicos e personalizados. O trabalho tem por objetivo mostrar quais foram os diferenciais inovadores que possibilitaram a criação e sucesso do estúdio no Norte de Portugal, que surgiu em Bragança, em 2019 e, atualmente, possui outras duas unidades. Por fim, se concluiu que as estratégias adotadas como diferenciais competitivos foram as principais responsáveis pelo sucesso online e físico dos estúdios