Browsing by Issue Date, starting with "2024-10-29"
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- A influência das quotas de representação de género nos conselhos de administração no desempenho das organizações : uma meta-análise qualitativaPublication . Moinhos, Patrícia Filipa Félix; Oliveira, Eva Teresa Valente Dias de; Guimarães, Maria Isabel Gonçalves Guedes de CastroO presente trabalho final de mestrado tem como objetivo compreender como é que as quotas de representação de género nos Conselhos de Administração se refletem no desempenho das organizações. Historicamente, as mulheres sempre enfrentaram dificuldades na questão de igualdade de direitos e, consequentemente, no alcance de cargos de liderança nas organizações. A legislação baseada em quotas de género, implementada primeiramente no campo político, transacionou-se nos últimos anos para a gestão, verificando-se uma redução das disparidades de género na liderança das organizações. A nível europeu, diferentes países estabeleceram diferentes leis em matéria de quotas de género, no entanto, existe ainda um importante percurso a ser feito, rumo ao equilíbrio. Uma vez que a literatura apresenta diversos resultados a este respeito, o método utilizado para dar resposta a esta questão de investigação foi a Meta-Análise Qualitativa. A identificação e interpretação dos resultados da investigação dos últimos 5 anos acerca deste tema, permitiu obter uma amostra final de 38 artigos através da aplicação de um protocolo de investigação e do processo da análise de conteúdo. Ao responder à questão de investigação foi possível identificar quatro temas: (1) Desigualdade de Género nas Organizações; (2) Dinâmicas de Poder; (3) Efetividade das Quotas; (4) Debate sobre as quotas. Os resultados sugerem que, no geral, organizações com maior número de mulheres nos seus Conselhos de Administração reúnem mais benefícios e resultados positivos no âmbito financeiro e social, contribuindo para um melhor e mais competitivo desempenho.
- The role of circular economy in the decarbonization of the agrifood sector in PortugalPublication . Resende, Daniela; Ribeiro, Tânia; Coelho, Marta; Oliveira, Nuno; Sousa, Daniel; Fazenda, Paula; Braga, Eduardo; Carvalho, Teresa; Pintado, Manuela
- Be@t: sustainable chemical processes for developing regenerative materials and ingredients in the textile industryPublication . Afonso, Tiago B.; Bonifácio-Lopes, Teresa; Costa, Eduardo M.; Costa, Ana Filipa; Oliveira, Juliana; Pintado, ManuelaIntroduction: The reuse and valorization of waste and by-products generated by other industrial sectors in the textile sector currently represents a strategy of 'sustainable waste minimization,' leading to the achievement of economic development and environmental sustainability goals. In recent years, waste and by-products from industrial processing, e.g., agro-industry, agroforestry, marine, canning, mining, leather, cork industries, among others, have been a source of bioactive compounds with potential application in the textile industry, as it is possible to extract a wide variety of compounds with a broad range of functionalities. A good example is agro-food waste and by-products, which are excellent sources of biological compounds that can be explored as raw materials to replace fossil fuels, complementing the use of forest biomass and adding value in obtaining new bio- based materials that are more versatile and sustainable. In the classification of bio- based materials, there are three major groups that can be valorized: protein- based, polysaccharides, and polyphenols. Among the most common protein- based materials derived from animal sources are keratin, collagen, and gelatin, which are often obtained from waste and by-products of industries like leather industry. These materials present valuable opportunities for sustainable reuse and resource efficiency. The extraction of these types of proteins is generally carried out through alkaline hydrolysis in combination with thermal processes, with or without the use of enzymes. Wastes/by-products from the agrifood industry can also serve as a natural source of functional dyes rich in phenolic compounds. These extracted materials can promote various functionalities of interest when applied to the textile and clothing industry, such as repellency, easy cleaning, anti-odor, flame retardancy, fluorescence, antioxidant, antimicrobial properties, among others. Although some methods for the extraction and valorization of waste and by- products are already described in the literature, one of the difficulties observed relates to scalability, the lack of interaction between industries, and the suitability of ingredients for textile industry processes. Aim: The main objective of this study is to identify the most effective technologies, utilizing diverse raw materials and processes, to develop active agents suitable for application in the textile industry. The goal is to contribute to the creation of greener processes and products that support industrial symbiosis and promote a circular bioeconomy. Materials and methods: Two approaches were tested based on different industrial by-products. These included by-products from the leather and agro-food industries. For the leather by- products the work focused on exploring different enzymes and hydrolysis conditions for the repurposing of leather towards the creation of versatile functional coatings to be re-used within the leather industry. The characterization of the samples was done using different methodologies, including SE-HPLC analyses to determine MWs, hydrolysis percentage (TNBS), total protein (BCA and Kjeldahl) and antioxidant activity (ORAC). The second approach was to extract phenolic compounds from different by-products of the agro-food industry through green and sustainable extraction methodologies. The obtained extracts were then characterized regarding their sugar, total phenolic and flavonoid content, as well as their biological potential as antioxidants and antimicrobials. Their cytotoxicity was also evaluated. Main results: Regarding leather hydrolysis, the results showed that all the enzymes were effective in processing the leather by-product. It was also possible to conclude that Alcalase provided better hydrolysis performance than ProtaBate P and Bromelain. Alcalase showed the highest hydrolysis degree, leading to peptides mixtures with MWs between 10 and 50 kDa and a high antioxidant activity. These results outline the potential of re-using leather by-products to create versatile functional coatings through a circular and more sustainable process. Regarding the extraction of phenolic compounds from different by-products, the results revealed a high variability of results among the different studied parameters. The different extraction methods impacted the extraction of phenolic compounds and other components (aqueous vs hydroethanolic vs ultrasound extraction methods). Sugar content varied significantly among by-products and extraction methods with apple skin aqueous extract having the highest amount of sugar. Total phenolic content of the by-products ranged from 4,4 to 512,9 mg GAE/g and flavonoid content from 2,1 to 287,8 mg CAE/g of sample. Antioxidant activity of the by-products followed the same pattern observed for the total phenolic content. Gram-negative bacteria (E. coli and P. aeruginosa) were more resistance to the extracts than Gram- positive (S. aureus and S. epidermidis). The majority of the extracts showed cytotoxicity against HaCaT cell line at the tested concentrations. Conclusion: The conclusions of this study can be divided regarding the two different approaches. In relation to the leather by-products approach, this study outlines the potential of re-using leather by-products to create versatile functional coatings through a circular and more sustainable process. Regarding the agro-food by- products approach, while more studies are necessary, the results show that some by-products have great potential to be used as sources of functional compounds in the textile industry, especially lemongrass and peanut skin. Different extracts exhibit varying functionalities, with some showing superior antioxidant properties while others demonstrate enhanced antimicrobial activity. This variation underscores the need to select the appropriate extract based on the specific functional requirements of the application. Despite their cytotoxicity at the tested concentrations against the tested cell line, further studies should be conducted to better understand the concentration limits to be applied when dyeing different textiles with these extracts. As a final remark, a sustainable approach within the leather and agro-food industries can be implemented by upcycling side streams through eco-friendly methods to create high-value products. This valorization concept represents a shift from traditional linear production and consumption patterns towards a circular economy. This strategy shift not only contributes to reducing overall waste but also aligns itself with the 12nd UN sustainability goal (Ensure sustainable consumption and production patterns) by the re-use of its own by-products.
- Relação entre sustentabilidade ambiental e PMEsPublication . Brito, Leonardo Maria Pereira Martins Gouveia de; Costa, Leonardo Filipe Seixas BarretoO objetivo da dissertação foi a de explorar a relação existente na literatura entre sustentabilidade ambiental e Pequenas e Médias Empresas (PMEs). O método utilizado foi uma Revisão Sistemática da Literatura (RSL) do tipo exploratório. Os resultados da RSL identificaram 40 artigos científicos distribuídos por 5 tópicos principais de investigação: i) inovação verde, sustentabilidade ambiental e economia circular; ii) transformação digital; iii) cadeias de valor global; iv) liderança e cultura organizacional; e v) desempenho ambiental e competitividade. A inovação verde, a sustentabilidade ambiental e a economia circular são a forma como a literatura aborda a adoção de boas práticas ambientais pelas PMEs, sendo que um desafio importante é a inexistência de métodos padronizados de medição. A transformação digital é crucial para a eficiência operacional e minimização dos impactos ambientais, mas requer investigações adicionais para entender os efeitos de tecnologias específicas. A manufatura aditiva pode transformar a gestão das cadeias de valor global, reduzindo custos de transporte e emissões de gases com efeitos de estufa e aumentando a sua resiliência. A liderança eficaz é essencial para desenvolver e manter uma cultura organizacional que valorize a sustentabilidade, sendo influenciada por pressões institucionais e regulamentares. Por fim, a adoção de práticas ambientalmente sustentáveis pelas PMEs pode conduzir à melhoria da sua competitividade, por via da redução de custos
- Behavioural finance : was the crypto market significantly impacted by herding behaviour from 2019 to 2024?Publication . Gouveia, Rodrigo Alberto Evangelista; Ferreira, Mário Pedro Leite de AlmeidaThis study investigates herding behaviour in the cryptocurrency market between January 1, 2019, and January 1, 2024, analysing five major cryptocurrencies and an index. The findings reveal a nuanced relationship: while a weak direct link exists between linear market returns and return dispersion, significant non-linear factors suggest investors in these markets tend to make diverse and autonomous decisions rather than herd. This challenges traditional understandings of investor behaviour in volatile markets like cryptocurrencies, underscoring the importance of considering non-linear factors such as psychological influences, market-specific conditions, and the impact of external events like the COVID-19 pandemic in analysing market dynamics. The findings have important implications for various stakeholders. Policymakers can better design regulations to enhance market stability. Investors can refine their strategies with a better understanding of market dynamics. Additionally, cryptocurrency developers can better judge market sentiment, enabling more informed innovations.
- Is the extraversion of French retail investors linked to their overconfidence bias? : an exploratory study on the overconfidence levels of French retail investorsPublication . Costa, Carlos Daniel Pereira da; Ferreira, Mário Pedro Leite de AlmeidaThis dissertation examines the extraversion and overconfidence concepts and does an in-depth exploration of the psychological mechanisms that explain the connection between the two factors. Using a cross-section sample of primary data collected from 104 French retail investors between December 2023 and January 2024, we explore the extraversion and overconfidence levels of French retail investors and use Spearman’s rank-correlation coefficient test to measure the correlation between the two. Findings suggest that although French retail investors display low levels of overconfidence, their extraversion is positively and significantly correlated to the overconfidence bias, especially when they are highly educated or have less than 2 years of experience. This implies that French retail investors could measure their extraversion levels to gauge whether they are prone to being overconfident during decision making and adjust their decision-making accordingly. The results also imply that French regulators should target highly educated and inexperienced investors as they tend to be more prone to becoming overconfident. This thesis covers a population and a culture type that had yet to be studied in this form.
- Efeito de compostos fenólicos no crescimento e no comportamento fermentativo de saccharomyces cerevisiaePublication . Silva, Duarte Roque da; Couto, José António GomesA influência de compostos fenólicos na fermentação de mostos vínicos por Saccharomyces cerevisiae tem vindo a ser estudada há algum tempo, mas não ao ponto, ainda, de permitir tirar conclusões consensuais. O objetivo deste trabalho foi investigar o efeito de compostos fenólicos no crescimento e no comportamento fermentativo de S.cerevisiae em condições enológicas simuladas, nomeadamente avaliar o efeito na produção de etanol e glicerol e na composição volátil dos vinhos sintéticos obtidos. Os compostos fenólicos testados foram o ácido cafeico, o ácido gálico e dois taninos, um extraído das películas e outro das sementes das uvas (A e B). Ao contrário da maior parte dos estudos publicados sobre este tema, observou-se que estes compostos estimularam o crescimento da levedura, acelerando a fase exponencial de crescimento e conduzindo a valores mais elevados de biomassa final. O metabolismo de açúcares foi afetado pela presença de compostos fenólicos com reflexo nas quantidades de etanol e glicerol obtidas. Curiosamente, o maior consumo de glucose e frutose não conduziu a uma maior produção de etanol e glicerol. O perfil aromático dos vinhos também foi influenciado pelos compostos fenólicos, notando-se um aumento na produção de ésteres. A produção de álcoois superiores e ácidos gordos, para além do efeito dos compostos fenólicos, foi também influenciada pela composição nutricional do meio, sendo aumentada pela inclusão de extrato de levedura. Podemos concluir que os compostos fenólicos afetam o comportamento fermentativo de S.cerevisiae com reflexo na composição química dos vinhos. O maior ou menor impacto dependerá do tipo de composto fenólico, da sua concentração e da composição nutricional do meio.
- A paradigm shift in skincare through the power of grape seed-loaded liposomesPublication . Castro, Maria Leonor de; Azevedo-Silva, João; Valente, Diana; Machado, Adriana; Ribeiro, Tânia; Ferreira, João Paulo; Pintado, Manuela; Ramos, Oscar; Borges, Sandra; Baptista-Silva, SaraThe skin undergoes natural aging and is prone to various conditions/pathologies due to constant exposure to environmental stressors and abrasions. The cosmetic industry has revolutionized skincare, each time in a higher trend for natural and organic products. The growing trend of clean beauty, driven by consumer demand for non-toxic and environmentally friendly products, is increasingly intertwined with sustainability, as brands and consumers alike prioritize ethical sourcing, eco-conscious packaging, and responsible production practices to reduce environmental impact and promote holistic well-being. Plant-derived natural ingredients are increasingly popular in cosmetic formulations due to their bioactive properties and sustainability. Among these, grape by- products are notable for their bioactive molecules, which exhibit significant biological activities. Utilizing these by-products is crucial, but many bioactive compounds like polyphenols are unstable and prone to degradation. Encapsulation in liposomes has emerged as an effective strategy to enhance their stability, skin penetration, among other characteristics. This study involved the extraction of two grape seed extracts: one from a single grape variety (GSE-Ov) and another from a mixture of five varieties (GSE-Sv). Both extracts were evaluated for their antioxidant and antimicrobial properties, along with their chemical composition and molecular structure. The GSE-Ov extract demonstrated superior antioxidant activity, with a 2,2-Diphenyl-1-picrylhydrazyl (DPPH) IC50 of 0.079 mg/mL. It also showed antimicrobial effects against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), with minimum bactericidal concentrations (MBCs) of 3.125 mg/mL and 6.25 mg/mL, respectively. Furthermore, it did not display any antimicrobial activity against Staphylococcus epidermidis, what promises to not affect the skin microbiota equilibrium. The key polyphenols identified in GSE-Ov included gallic acid, catechin, and procyanidin B1, and FTIR analysis confirmed that the extraction process preserved the extract's molecular integrity. This extract was encapsulated in pectin-coated soy lecithin liposomes, achieving an encapsulation efficiency of 88.8% and a polyphenol release rate of 59.4% over 24 hours. The liposomes were stable, with a zeta potential of -20.3 mV, an average diameter of 13.6 μm, and a uniformity index of 0.637. They were found to be safe under the concentrations of 5 and 2.5 mg/mL in HaCaT and HDF cell models, respectively, and demonstrated anti-inflammatory effects against IL- 1α at 2 mg/mL. This study is an evident first line of research that brings together the potential of grape- seeds as by-products and the clenched systems to encapsulate them. The study addresses all paradigms of eco-conscious innovation, sustainability and circular economy.