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Solventes verdes para a dissolução de plásticos
No full textOs resíduos plásticos estão atualmente a ser produzidos a um ritmo preocupante, aproximando-se de 300 milhões de toneladas por ano, das quais apenas 10% são recicladas, o que contribui para a rápida acumulação destes materiais no ambiente. Assim, é prioritário desenvolver métodos de reciclagem de plásticos mais eficientes e acessíveis, garantindo simultaneamente a preservação da qualidade dos polímeros reciclados. Entre os diferentes processos de reciclagem, a dissolução/precipitação – um método de reciclagem física – surge como uma solução promissora, uma vez que permite recuperar o polímero com preservação das suas propriedades. No entanto, a utilização de solventes orgânicos voláteis convencionais tem sido a escolha mais comum, motivando a procura de solventes alternativos mais eficientes e sustentáveis. Neste sentido, o principal objetivo deste trabalho foi analisar a dissolução de poliestireno (PS) em solventes alternativos à base de terpenos e nas suas respetivas misturas eutécticas a temperaturas
moderadas. Numa primeira fase, a capacidade de dissolução de vários solventes foi avaliada através de ferramentas preditivas, nomeadamente o COnductor-like Screening Model for Realistic Solvents (COSMO-RS) e os parâmetros de solubilidade de Hansen. Posteriormente, os melhores solventes foram testados experimentalmente na dissolução de PS. Após as análises, constatou-se que os solventes que apresentaram os melhores resultados de dissolução a 60 ºC foram o p-xileno, α-pineno, β-pineno, fenchona, p-cimeno e as amostras industriais de terebintina pinaster e terebintina elliottii. As propriedades do polímero, avaliadas por
Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) indicaram que não houve alterações estruturais significativas. De uma forma geral, os solventes utilizados neste estudo mostraram-se bastante promissores na dissolução de PS, destacando-se como alternativas mais sustentáveis para a reciclagem de plásticos. Esta abordagem não só promove a circularidade dos polímeros, como também abre caminho
para processos de reciclagem de plásticos industriais mais ecológicos e economicamente viáveis.Plastic waste is currently being produced at an alarming rate, approaching 300 million tons per year. However, only 10% of this plastic is recycled, which significantly contributes to the rapid accumulation of these materials in the environment. Therefore, it is a priority to develop more efficient and accessible plastic recycling methods while simultaneously ensuring the preservation of the quality of the recycled polymers. Among the different recycling processes, dissolution/precipitation – a physical recycling method – emerges as one of the most promising options since the quality of the polymer is preserved. However, until now, the use of conventional volatile organic solvents has been the most common choice, encouraging the search for more efficient and sustainable alternative solvents. In this context, the main objective of this work is to analyze the
dissolution of polystyrene (PS) in alternative solvents based on terpenes and in their respective eutectic mixtures at moderate temperatures. In the first phase, the dissolution ability of several solvents was evaluated using predictive tools, namely the Conductor- like Screening Model for Realistic Solvents (COSMO-RS) and the Hansen solubility parameters. Next, the best solvents were experimentally tested for dissolving PS. The
characteristics of the polymer were evaluated before and after dissolution using different analytical techniques. After the analyses, it was found that the solvents showing the best dissolution results at 60°C were p-xileno, α-pineno, β-pineno, fenchone, p-cymene, and the industrial samples of pinaster turpentine and elliottii turpentine. The characteristics of the polymers post-dissolution show that there are not significant structural changes. Overall, the solvents used in this study proved to be quite promising in dissolving PS,
standing out as more sustainable alternatives for plastic recycling. This approach not only promotes the circularity of polymers but also points to the possibility of developing more ecological and economically viable recycling processes.Este trabalho foi suportado por fundos nacionais através da FCT/MCTES (PIDDAC):
UIDB/00690/2020 (DOI: 10.54499/UIDB/00690/2020) e UIDP/00690/2020 (DOI:
10.54499/UIDP/00690/2020); e SusTEC, LA/P/0007/2020 (DOI:
10.54499/LA/P/0007/2020
A responsabilidade social corporativa no setor olivícola de Trás-os-Montes e Alto Douro
Full text linkMestrado em IPB-ESTG e ASSOCIAÇÃO DE POLITÉCNICOS DO NORTE (APNOR): Instituto Politécnico do Cávado e do Ave, P. Porto, Instituto Politécnico de Viana do CasteloA presente investigação pretendeu analisar a implementação da Responsabilidade Social Corporativa (RSC) no setor olivícola de Trás-os-Montes e Alto Douro, com o objetivo de avaliar se as organizações do setor estão alinhadas com as práticas de RSC e como estas impactam os seus negócios. A investigação foi motivada pela crescente importância da RSC no contexto global marcado por incertezas económicas, sociais e ambientais, onde a sustentabilidade empresarial é cada vez mais valorizada.
Para conduzir o estudo foi utilizada uma metodologia mista, combinando questionários aplicados a diferentes organizações do setor, com a realização de entrevistas, para complementar o estudo. Os resultados mostraram que, embora todas as organizações sejam conhecedoras da importância da RSC, existem variações significativas na implementação dessas práticas. As cooperativas demonstraram uma maior preocupação com o equilíbrio entre os aspetos económicos e sociais, enquanto as empresas privadas enfrentam desafios relacionados com a falta de recursos humanos e financeiros. Além disso, constatou-se que a maioria das organizações não elabora relatórios de sustentabilidade, e que a burocracia é um dos maiores obstáculos para a implementação da RSC. As principais conclusões indicam que as práticas de RSC no setor olivícola são limitadas pela dimensão das organizações e pela falta de apoio técnico e financeiro.
Este estudo sugere a necessidade de investigações futuras a nível nacional para ampliar a compreensão do tema e comparar diferentes classes de empresas quanto às suas práticas de RSC.This dissertation investigates the implementation of Corporate Social Responsibility (CSR) in the olive sector of Trás-os-Montes and Alto Douro, aiming to assess whether organizations in the sector are aligned with CSR practices and how these impact their business operations. The research was motivated by the growing importance of CSR in a global context marked by economic, social, and environmental uncertainties, where corporate sustainability is increasingly valued.
A mixed methodology was employed, combining questionnaires distributed to various organizations in the sector with interviews to supplement data analysis. The findings reveal that, while all organizations are aware of the importance of CSR, there are significant variations in the implementation of these practices. Cooperatives showed a greater concern for balancing economic and social aspects, whereas private companies face challenges related to limited human and financial resources. Additionally, it was found that most organizations do not produce sustainability reports, and that access to external financial support is one of the biggest obstacles to effective CSR implementation.
The main conclusions indicate that CSR practices in the olive sector are constrained by the size of the organizations and the lack of technical and financial support. This study suggests the need for future research at the national level to broaden the understanding of the topic and to compare different classes of companies regarding their CSR practices
Multifunctional lignin-based pickering emulsions for cosmetic applications
No full textMestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáLignin is one of the most abundant polymers on Earth, and currently, around 95% of the extracted lignin is used to generate energy in industries. Lignin has remarkable properties that add high value as a raw material for developing new products. The main properties explored include antioxidant capacity, UV protection, and stabilization of oil-water interfaces, i.e., as Pickering emulsion stabilizers. These properties present the potential to formulate pharmaceutical and cosmetic products in high demand for environmentally eco-friendly
products containing natural ingredients. Plant extracts mostly contain bioactive compounds, such as polyphenols and flavonoids (i.e., quercetin and ferulic acid), which can potentiate the
bioactivity of lignin-based formulations. In this context, this work aimed to develop colloidal
lignin-quercetin particles (CLQPs) to stabilize Pickering emulsions for cosmetic applications.
For this, different conditions of the particle production process were studied, including the use
of new lignin types, the solvent and antisolvent used, and the addition of purification steps. The
optimized CLQPs consisted of using LIGNOVA Pure™ as the lignin type solubilized in 80%
acetone aqueous solution (v/v) with a final concentration of 20%, pH 8 buffer as the antisolvent,
and precipitation using the classic method. The optimum percentage of quercetin in the composition of the particles was 50% (w/w) relative to lignin (Q_50), which showed a median particle size of 462 ± 1 nm, an oil-water contact angle of 91.6 ± 0.1°, and a zeta potential of - 52.8 ± 2.7 mV. The optimized particles were used to stabilize Pickering emulsions (EQ_50), which showed the best oil-water ratio as 60/40, the smallest of the tested ratios, showing average droplet sizes of 26 ± 1 μm. The optimized emulsion was used to encapsulate ferulic acid (EQ_50F), which showed a yellowish-brown color, an emulsified layer of approximately 90%, an antioxidant activity (IC50) of 0.16 ± 0.35 mg/mL, a non-Newtonian shear-thinning fluid and gel-like behavior based on rheology tests, and a high stability during the 30 days period of storage. Therefore, the association of lignin and flavonoids is a promising strategy for formulating new bio-based cosmetics by combining the best properties of both components.A lenhina é um dos polímeros mais abundantes na Terra e, atualmente, cerca de 95% deste componente é extraído e usado para gerar energia nas indústrias. A lenhina tem propriedades notáveis que lhe conferem alto valor acrescentado como matéria-prima para o desenvolvimento de novos produtos. As principais propriedades exploradas incluem capacidade antioxidante, proteção UV e estabilização de interfaces óleo-água, ou seja, como estabilizadores de emulsões Pickering. Essas propriedades apresentam potencial para formular produtos farmacêuticos e cosméticos, áreas que têm uma elevada procura por produtos ecologicamente corretos contendo ingredientes naturais. Os extratos de plantas contêm, em sua maioria, compostos bioativos, como polifenóis e flavonoides (por exemplo, quercetina e ácido ferrúlico), que podem
potencializar a bioatividade de produtos de base lenhina. Nesse contexto, este trabalho teve como objetivo desenvolver partículas coloidais de lenhina-quercetina (CLQPs) para estabilizar emulsões Pickering para aplicações cosméticas. Para isso, foram estudadas diferentes condições do processo de produção das partículas, incluindo o uso de novos tipos de lenhina, o tipo de solvente e o antissolvente usados e a consideração de etapas de purificação. As CLQPs otimizadas consistiram no uso da lenhina LIGNOVA Pure™ solubilizada em solução aquosa de acetona 80% (v/v) com uma concentração final de 20% e utilização de um tampão pH 8 como antissolvente, utilizando o método clássico de precipitação. A percentagem ideal de quercetina na composição das partículas foi de 50% (w/w) em relação à lenhina (Q_50), apresentando um tamanho médio de partícula de 462 ± 1 nm, um ângulo de contato óleo-água
de 91,6 ± 0,1° e um potencial zeta de -52,8 ± 2,7 mV. As partículas otimizadas foram usadas na estabilização de emulsões Pickering (EQ_50), apresentando como melhor relação óleo/água 60/40, a menor das razões testadas, obtendo-se um tamanho médio de gota de 26 ± 1 μm. A emulsão otimizada foi usada para encapsular o ácido ferrúlico (EQ_50F), apresentando uma cor castanha-amarelada, uma camada emulsificada de aproximadamente 90%, uma atividade antioxidante (IC50) de 0,16 ± 0,35 mg/mL, características de fluido não newtoniano pseudoplástico com um comportamento semelhante a um gel com base na análise reológica e uma estabilidade elevada durante os 30 dias de armazenamento. Concluindo, a associação de lenhina e flavonoides é uma estratégia promissora para a formulação de novos cosméticos de
base biológica, combinando as melhores propriedades de ambos os componentes
Development of a GC-MS methodology for determining the adulterant 2,4-dinitrophenol in weight loss food supplements
Full text linkMestrado de dupla diplomação com o Centro Federal de Educação Tecnológica de Minas Gerais – CEFET-MGCurrently, the pursuit of a body that meets beauty standards has become a major goal for a large part of the population, greatly intensified by pictures of perfect bodies shared on social networks. This has impelled the growth of the “fitness” market, which offers a wide range of products for weight loss, including plant food supplements (PFS). Since overweight currently affects millions of individuals worldwide, weight-loss products are undoubtedly one of the most popular types of PFS. However, different reports, including from the Food and Drug Administration (FDA) and the EU Rapid Alert System of Food and Feed (RASFF), have raised concerns about fraudulent practices in this sector, particularly the addition of pharmaceutical drugs to boost the PFS effect. Different adulterants have been reported in PFS supplements, including 2,4-dinitrophenol (2,4-DNP), a compound used in the 1st World War to produce ammunition that showed weight loss as a
side effect. Although 2,4-DNP is able to cause weight loss, it is associated with a high rate of dangerous effects since the drug causes the uncoupling of mitochondrial oxidative phosphorylation, leading to hyperthermia and diaphoresis, which, together with tachycardia and decreased blood pressure, can lead to death. Nevertheless, due to its thermogenic capacity, 2,4-DNP is a potential adulterant of weight loss PFS. Therefore, this work aimed at developing a methodology using gas chromatography coupled with
mass spectrometry (GC-MS) to identify and quantify this compound if present in commercial samples of PFS. After optimization of the GC-MS operational parameters and derivatization procedure, the methodology was validated following the general guidance “ICH Q2 Validation of analytical procedures” of the European Medicines Agency (EMA) for method validation. All the parameters followed the EMA guideline including
specificity, linearity, range of the curve, precision, accuracy, detection and quantification limit, and matrix effect. The calibration curve was shown to be linear within the range of 5 ppm to 0.05 ppm, with a limit of quantification of 0.05 mg/L and a limit of detection of 0.015 mg/L. Subsequently, the methodology was applied to a small set of commercial supplements, with the compound not being detected in any of the analyzed products
Backpackers’ Space–time Behaviour in a World Heritage City-Porto
No full textUrban tourism is one of the most popular forms of tourism, but it remains an understudied phenomenon, particularly in terms of tourists’ spatiotemporal behaviour. The aim of this research is to analyse the spatiotemporal behaviour of the backpacker tourists in an urban destination classified as World Heritage. Data collection was done through a questionnaire survey (n = 292) and a GPS App to track backpacker tourist movements (n = 82) during a visit day to Porto, Portugal. All the thematic cartography was developed with QGIS 3.2.0 software. A map with the movements performed by all backpacker tourists; a map with the intensity of the backpacker movements (passages by area, 50 × 50 m) and a map with the distribution of the total length of stay by area (50 × 50 m), allowed the identification of the main hotspots as well as the non-visited territories in Porto urban area. Relevant contributions for destination managers are presented and discussed.info:eu-repo/semantics/publishedVersio
Literacy, Resilience, and Financial Well-Being in Higher Education Students
No full textThe authors assessed the determinants of the overall financial literacy indicator of higher education students in Portugal and the relationship between the financial literacy indicator and the indicators of resilience and financial well-being. Based on a non-parametric quantitative analysis, the authors used a sample of 469 higher education students. They observed that students present globally more satisfactory indicators compared to the Portuguese population and are influenced by demographic factors such as age, gender, level of education, and income. The results are far from reasonable, especially in the dimension related to knowledge. As also statistically confirmed, there exists a positive and significant relationship between the financial literacy indicator and the indicators of resilience and financial well-being. Therefore, this study adopts a novel approach that intends to link these indicators with higher education students, as there is still a lack of research that addresses the concept of digital financial literacy within this context.info:eu-repo/semantics/publishedVersio
El impacto de los factores macroecono micos en el sector europeo de viajes y ocio: el contexto de la guerra ruso-ucraniana
No full textThis study aims to address the macroeconomic factors effect on the travel and leisure (T&L) industry throughout Europe within the context of the Russo-Ukrainian war that have started on 24 February 2022. Specifically, top tourist destinations are analysed, such as Spain, France, Italy and Portugal, as well as Europe in general.
Design/methodology/approach – This study adopts the panel regression approach based on the data that is provided on a daily basis, and it covers a period of nearly 14 months, starting on 24 February 2022 and ending on 15 April 2023.
Findings – The findings indicate that the European T&L sector is impacted by macroeconomic variables. Namely, the T&L sector is significantly impacted by interest rates, geopolitical risk, oil and gas, whereas inflation has a muted effect, indicating a comparatively lesser influence on the dynamics of the industry. This research contributes to existing literature by providing one of the first quantitative analyses of how macroeconomic factors impact the European T&L business in the context of a geopolitical conflict.
Research limitations/implications – A study of the Russian–Ukrainian war may be limited by a number of research constraints. The continuing nature of the conflict, the lack of communication between the parties and potential political prejudice are some of these difficulties. Any research on the Russo- Ukrainian war should be done with these limits in mind.
Practical implications – Macroeconomic variables play a significant role on the T&L sector development; therefore, when designing resilience strategies, they need to be accounted for. Originality/value – To the best of authors’ knowledge, this is one of the first studies to analyse how macroeconomic factors affected the European T&L business using a quantitative approach. The macroeconomic variables that were taken into account in this study included interest rates, inflation, oil and petrol prices, as well as the geopolitical risk index.La presente investigación aborda el efecto de los factores macroeconómicos en la industria de viajes y ocio (VyO) en toda Europa en el contexto de la guerra ruso-ucraniana que comenzó el 24 de febrero de 2022. En concreto, se analizan los principales destinos turísticos, como España, Francia, Italia y Portugal, así como Europa en general.
Metodología: El estudio adopta un enfoque de regresión de panel basado en datos diarios y cubre un período de casi 14 meses, del 24 de febrero de 2022 al 15 de abril de 2023.
Resultados: Nuestros resultados indican que el sector europeo de VyO se ve afectado por variables macroeconómicas. En concreto, el sector se ve significativamente afectado por los tipos de interés, el riesgo geopolítico, el petróleo y el gas, mientras que la inflación tiene un efecto moderado. Limitaciones de la investigación: Un estudio de la guerra ruso-ucraniana puede verse limitado por una serie de restricciones a la investigación. La persistencia del conflicto, la falta de comunicación entre las partes y los posibles prejuicios políticos son algunas de estas dificultades. Cualquier investigación sobre la guerra ruso-ucraniana debe hacerse teniendo en cuenta estos límites.
Implicaciones prácticas: Las variables macroeconómicas desempeñan un papel importante en el desarrollo del sector de VyO, por lo que es necesario tenerlas en cuenta al diseñar estrategias de resiliencia.
Originalidad: Hasta donde sabemos, este es uno de los primeros estudios que analiza cómo los factores macroeconómicos afectaron al negocio europeo de VyO utilizando un enfoque cuantitativo. Las variables macroeconómicas que se tuvieron en cuenta en este estudio fueron los tipos de interés, la inflación, los precios del petróleo y de la gasolina, así como el índice de riesgo geopolítico.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to UNIAG (UIDB/04752/2020 and UIDP/ 04752/2020).info:eu-repo/semantics/publishedVersio
How can design thinking improve food sustainability in the Minho region (eno)gastronomy? A multi-actor perspective
No full textPurpose | This study has the following main goals: i) to define barriers and present specific solutions associated with the food ecosystem, common to the various actors in the territory; ii) to explore the present and future of Minho's (eno)gastronomy and iii) provide innovative responses that meet contemporary consumer demands in terms of health and sustainability.
Methodology/Approach | Trough Design Thinking, we pursued a collaborative approach that melds gastronomic
traditions with health and sustainability imperatives, ensuring holistic solutions that valorize Minho’s heritage. The process involved iterative workshops, engaging diverse stakeholders to analyze the historical and current state of Minho’s (eno) gastronomy, focusing on the transition to healthier and more sustainable practices. This multi-actor approach enabled integrated solutions, enhancing the food system while considering climate change impacts and modern health trends.
Expected Results | The topics addressed by the region's players associated with the agri-food sector and the solutions proposed highlighted the intrinsic relationship between local production and sustainability, emphasising that the proximity between producer and consumer translates not only into a smaller carbon footprint, but also into the socioeconomic and cultural enhancement of the region. These results will enable policymakers to apply a multi-actor approach, taking into account the needs of the various stakeholders in the region and implementing concerted actions that jointly respond to the challenges and needs we have identified.info:eu-repo/semantics/publishedVersio
Positioning Cyber-Physical Systems and Digital Twins in Industry 4.0
Full text linkIndustry 4.0 has brought innovative concepts and technologies that have greatly improved the development of more intelligent, flexible and reconfigurable systems. Two of these concepts, Cyber-Physical Systems (CPSs) and Digital Twins (DTs), have gained significant attention from various stakeholders, e.g., researchers, industry practitioners, and governmental organizations. Both are vital to support the digitalisation of products, machines, and systems, and they focus on the integration of physical and cyber processes, where one affects the other through feedback loops. Having this in mind, this paper aims to better understand how CPS and DT are correlated, particularly exploring their similarities and differences, their positioning within the Industry 4.0 paradigm, and their convergence to develop Industry 4.0 solutions. Some research challenges to develop Industry 4.0 solutions by integrating these concepts are also discussed.This work was partially supported by the HORIZONCL4-2021-TWIN-TRANSITION-01 openZDM project, under Grant Agreement No. 101058673. Authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CeDRI (UIDB/05757/2020 and UIDP/05757/2020) and SusTEC (LA/P/0007/2021). Authors Flavia Pires and Victória Melo thank the FCT Portugal for the PhD Grant SFRH/BD/143243/2019 and 2022.13868.BD, respectively.info:eu-repo/semantics/publishedVersio
Actively detecting multiscale flooding attacks & attack volumes in resource-constrained ICPS
Full text linkThe significant growth in modern communication technologies has led to an increase in zero-day vulnerabilities that degrade the performance of cyber-physical systems (ICPS). Distributed denial of service (DDoS) attacks are one such threat that overwhelms a target with floods of packets, posing a severe risk to the normal operations of the ICPS. Current solutions to detect DDoS attacks are unsuitable for resource-constrained ICPS. This study proposes actively detecting multiscale flooding DDoS attacks in resource-constrained ICPS by analyzing network traffic in the frequency domain. A two-phased technique detects attack presence and attack volume. Both phases use a novel combination of light-weight and theoretically sound statistical methods. The effectiveness of the proposed technique is evaluated using mainstream metrics like true and false positive rates, accuracy, and precision using BOUN DDoS 2020 and CICDDoS 2019 datasets. An implementation of the proposed approach on a programmable logic controllers-based ICPS demonstrated improvements in resource usage and detection time compared to the existing state-of-the-art.info:eu-repo/semantics/publishedVersio