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Implementação de modelos in vitro e ex vivo de folículo capilar
No full textDissertação de mestrado em BiotechnologyA procura de modelos celulares que mimetizem a bilogia e fisiologia do folículo capilar é um tema pertinente e atual na investigação e desenvolvimento de soluções eficazes para o tratamento das doenças que o afetam. Com o objetivo de encontrar um modelo expedito para teste de biomoléculas de interesse no tratamento da alopecia androgénica e da alopecia quimicamente-induzida, este trabalho propõe o desenvolvimento de um modelo 3D, composto por células da papila dérmica imortalizadas (hHFDP) em conjunto com queratinócitos epidermais (HaCaT) ou foliculares (ORS). A formação dos esferoides foi conseguida através das técnicas da gota suspensa e da cultura em microplacas com superfícies de adesão ultrabaixa. Vários parâmetros foram avaliados e otimizados. A junção das duas técnicas mostrou ser o método mais adequado, originando esferoides mais compactos com uma forma mais arredondada e bem delimitada. Os esferoides mistos foram obtidos de duas formas diferentes: através da mistura simultânea e não simultânea dos dois tipos celulares. A mistura não simultânea permitiu o desenvolvimento de esferoides mistos compostos por um núcleo de células da papila dérmica rodeado por queratinócitos. Os esferoides simples ou mistos obtidos pela metodologia otimizada foram testados para avaliar o efeito de moléculas tipo, associadas à alopecia androgénica, na sua capacidade de mimetizar a resposta esperada de um folículo de cabelo. Foi avaliado o efeito na viabilidade de culturas 2D e 3D do tratamento com testosterona e o seu derivado dihidrotestosterona, com vários fármacos, finasteride e minoxidil usados no tratamento da alopecia androgénica, docetaxel, ciclofosfamida e doxorubicina, três agentes quimioterapêuticos. As células HaCaT foram mais resistentes em co-cultura com e hHFDP, enquanto a co-cultura das células ORS e hHFDP mostrou menor viabilidade comparada à cultura com somente ORS. As interações estabelecidas e o modo como influenciam a resposta do modelo ao tratamento dependem do tipo de queratinócitos utilizado. Os resultados sugerem que o modelo 3D desenvolvido tem forte potencial, mas ainda requer otimização e testes adicionais para aprimoramento.The search for cellular models that mimic the biology and physiology of the hair follicle is a relevant and current topic in research and development of effective solutions for treating hair-related disorders. Aiming to establish a rapid and efficient model for testing bioactive molecules of interest in the treatment of androgenetic alopecia and chemotherapy-induced alopecia, this study proposes the development of a 3D model composed of immortalized dermal papilla cells (hHFDP) in combination with epidermal keratinocytes (HaCaT) or follicular keratinocytes (ORS).
Spheroid formation was tested using the hanging drop technique and cell culture microplates with ultra-low attachment surfaces. Several parameters were evaluated and optimized. The combination of both techniques proved to be the most effective approach, resulting in more compact, well-defined, and rounded spheroids. Mixed spheroids were generated using two different approaches: simultaneous and non-simultaneous mixing of the two cell types. The non-simultaneous mixing led to the development of mixed spheroids with a core of dermal papilla cells surrounded by keratinocytes.
Optimized simple and mixed spheroids were used to assess the effect of prototype molecules associated with androgenic alopecia and their ability to mimic the expected response of a hair follicle. The viability of 2D and 3D cultures was assessed after treatment with testosterone and its derivative dihydrotestosterone, as well as with drugs used to treat androgenic alopecia (finasteride and minoxidil) and three chemotherapeutic agents (docetaxel, cyclophosphamide, and doxorubicin). HaCaT cells exhibited greater resistance when co-cultured with hHFDP, whereas the co-culture of hHFDP and ORS showed lower viability compared to ORS alone. The interactions established and how they influence the model’s response to treatment depend on the type of keratinocytes used.
The results suggest that the developed 3D model holds promise; however, further optimization and additional testing are required
Enhancing the durability of concrete with construction and demolition waste aggregate through its functionalization with phase change materials (paraffin)
No full textIncorporating construction and demolition waste aggregate (DW) into concrete addresses environmental con
cerns by reducing the demand for virgin materials and diverting waste from landfills. However, the high porosity
of DW negatively impacts the durability of concrete. In this work, DW was functionalized by impregnating it with
paraffin to fill its inherent pores. Additionally, the phase change characteristics of paraffin were utilized to
partially infiltrate the interfacial transition zone pores, thereby minimizing the connected porosity within the
concrete. This work focuses on the durability of concrete containing DW and functionalized DW, examining
factors such as chloride ion penetration, sulfate magnesium attack, freeze-thaw cycles, and carbonation resis
tance. The findings reveal that concrete with 100 % functionalized DW achieved a 31.5 % improvement in
durability, exhibited zero carbonation depth, and demonstrated excellent resistance to freeze-thaw cycles,
highlighting the effectiveness of this approach in enhancing concrete performance.This work was partly financed by Portuguese Foundation for Science and Technology (FCT/MCTES) through Portuguese National funds (PIDDAC) under R&D Centre for Territory, Environment and Construction (CTAC), under reference UIDB/04047/2020 and UIBD/152844/202
Study of a new methodology for mycotoxin patulin’s capture
No full textDissertação de mestrado em Engenharia Química e BiológicaNo presente trabalho, foi avaliada a capacidade de interação entre diferentes proteínas e a micotoxina patulina (PAT) para posteriormente estudar a sua captura em soluções aquosas utilizando aerogéis preparados com as proteínas mais promissoras.
Para isto, foi estudada a capacidade de certas proteínas para ligarem a patulina utilizando o fenómeno de fluorescence quenching e assim determinar a força da interação entre ambas. Além disto, foi confirmada a captura de PAT pelas proteínas utilizando um método de ultrafiltração que permitiu separar e quantificar a patulina não-ligada à proteína. Por último, foram preparadas colunas com as melhores proteínas estruturadas na forma de aerogéis, e avaliada a quantidade de patulina capturada pelas mesmas utilizando high performance liquid chromatography (HPLC).
As proteínas que evidenciaram maior afinidade para a PAT foram as diferentes albuminas testadas. As constantes de afinidade determinadas variaram entre 9,09 x 103 M-1, com a proteína ovalbumina (OVA), e de 1,82 x 104 M-1, com a proteína recombinante TrxBD2. Nos ensaios de ultrafiltração a pH 7,4, a proteína metalotioneína (METAL) foi a única capaz de capturar a totalidade de PAT, mas a proteína OVA desnaturada a 90 °C (OVA90) também capturou cerca de 50 % da micotoxina. Em tampão a pH 3,5, a proteína METAL capturou 67 % da PAT presente na amostra enquanto a proteína OVA90 capturou apenas 27 %. Em ensaios com sumo de maçã contendo PAT, essas proteínas capturaram 64 % e 10 % da micotoxina, respetivamente.
As colunas de aerogel foram preparadas com OVA desnaturada a 80 °C e 90 °C. Os aerogéis capturaram, respetivamente, 96,6 % e 100 % da PAT quando a pH 7,4. A eluição da PAT capturada pelos aerogéis não foi alcançada de forma eficiente, tendo as recuperações de PAT sido inferiores a 10 % com acetonitrilo acidificado.
A captura de PAT foi conseguida em sistemas aquosos, através da ultrafiltração com as proteínas; e em sistema bifásico, utilizando proteínas imobilizadas na forma de aerogéis. No entanto, são necessários mais estudos para melhorar a sua recuperação.In this study, the interaction capacity between different proteins and the mycotoxin patulin (PAT) was studied in order to subsequently study its capture from aqueous solutions using aerogels prepared with the most promising proteins.
To this end, the ability of certain proteins to bind patulin was studied using the fluorescence quenching phenomenon and thus the strength of interaction between both was determined. In addition, the capture of PAT by the proteins was confirmed using an ultrafiltration method that allowed the separation and quantification of the patulin not bound to the protein. Finally, columns with the best proteins in the form of aerogels were prepared, and the amount of patulin captured by them was evaluated using high-performance liquid chromatography (HPLC).
The proteins that showed higher affinity for PAT were the tested albumins tested. The determined varied between 9.09 x 103 and 1.82 x 104 M-1. In the ultrafiltration tests at pH 7.4, the METAL protein was the only one capable of capturing all the PAT, but the ovalbumin (OVA) protein denatured at 90 °C (OVA90) also captured approximately 50 % of the mycotoxin. At pH 3.5, the metallothionein (METAL) protein captured 67 % of the PAT present in the sample, while the OVA90 protein captured only 27 %. In tests with apple juice containing PAT, these proteins captured 64 % and 10 % of the mycotoxin, respectively.
Aerogel columns were prepared with OVA denatured at 80 °C and 90 °C. The aerogels captured 96.6 % and 100 % of the PAT, respectively, at pH 7.4. The elution of the PAT captured by the aerogels was not achieved efficiently, with PAT recoveries being less than 10 % using acidified acetonitrile (ACN).
PAT capture by the proteins was achieved in aqueous systems, in ultrafiltration assays; and in a two-phase system, using proteins structures in the form of aerogels. However, further studies are needed to improve its recovery.Gostaria de agradecer à Fundação de Ciência e Tecnologia (FCT), pela oportunidade de trabalhar como aluna bolseira no projeto MycoProAffinity 2022.03438.PTDC, no âmbito do financiamento estratégico da unidade UIDB/04469/2020, e ao Professor Doutor Luís Abrunhosa que me orientou e auxiliou ao longo deste ano, meu sincero agradecimento por toda a sua paciência e todos os conselhos
Consequential life cycle assessment of bamboo leaf ash generation: a Brazilian context
No full textThe potential of biomass growth, such as from bamboo leaves, as a source of electricity provides an optimistic scenario for the sustainable development of new green building materials. To validate robust life cycle inventory (LCI) data for incoming high-quality silica sources for cementitious materials, a consequential life cycle assessment (CLCA) on the bamboo leaves ash (BLA) with a prospective approach was conducted. The LCI data was collected in Southeastern Brazil with a prospective maturity in biomass electricity system. The data was gathered by analyzing the various stages involved in the production of BLA, including bamboo cultivation, leaf collection, cogeneration, raw BLA beneficiation, and its impact on cement and electricity marginal production systems. According to the multifunctionality solution, the environmental impacts results of CLCA were discussed using a sensibility analysis with two attributional life cycle assessment (ALCA) scenarios as allocation and “zero environmental load” (considering BLA as residue). The scenarios demonstrate the potential for sustainable use of BLA, especially for its impact on climate change, including the biogenic carbon category. Also, consequences such as avoiding BLA landfilling and increasing the potential for bamboo agricultural holdings to become energy independent was included in the study conclusion. While these results are positive, the prospect of maturing electricity production requires the development of other high-quality materials, such as sugarcane bagasse ash, sugarcane leaf ash and rice husk ash. However, the positives consequences did not overcome the negative impacts from the transportation of BLA into its system boundaries, once the highway transport model is the manly in the Brazilian context. Hence, this study provides important and reproducible pathways for developing LCI data on other biomass ashes, assisting future studies on green building materials.This study was partly financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and supported by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020, and under the Associate Laboratory Advanced Production and Intelligent Systems
ARISE under reference LA/P/0112/2020
Nova biorrefinaria de algas marinhas através de bioprocessamento sequencial para obtenção de produtos de valor acrescentado para aplicação em aquacultura
No full textPrograma doutoral em Chemical and Biological EngineeringPara sustentar a expansão da indústria da aquacultura, a procura por ingredientes sustentáveis
e económicos para incluir nas rações está a aumentar. As macroalgas são um potencial recurso para
incorporar nas rações, devido à sua riqueza em nutrientes e à ausência de competição com as plantas
terrestres pelos usos de terra e água doce. No entanto, o seu teor em polissacarídeos prejudica a sua
inclusão nas rações, pelo que o bioprocessamento desta biomassa através de uma abordagem
biotecnológica como a fermentação em estado sólido (FES) pode ser vantajoso para aumentar o seu
valor biológico. Assim, em primeiro lugar, avaliou-se o potencial de cinco algas (Gracilaria sp., Porphyra
dioica, Codium tomentosum, Ulva rigida e Alaria esculenta) como substrato em FES com fungos
filamentosos (Aspergillus ibericus MUM 03.49 e Aspergillus niger CECT 2915). A FES de U. rigida com
ambos os fungos resultou em atividades máximas de xilanase e β-glicosidase, enquanto o seu conteúdo
em hidratos de carbono diminuiu 54% e 62% após a FES com A. ibericus e A. niger, respetivamente.
Além disso, o subproduto de Gelidium corneum após extração do agar (GBP) também foi utilizado em
FES com os mesmos fungos, mas não foram observadas diferenças no conteúdo de polissacarídeos,
para além da baixa atividade enzimática. Este substrato foi misturado com bagaço de girassol (1:1; Gmix)
e a FES desta mistura melhorou a produção de enzimas e o teor proteico do sólido fermentado, pelo que
esta mistura foi selecionada para ser incluída em dietas para robalo: 10% da mistura não fermentada
(dieta Gmix) ou fermentada por A. ibericus (dieta Gmix-ibericus) ou A. niger (dieta Gmix-niger). Em geral,
as dietas Gmix ou Gmix-ibericus não comprometeram o desempenho ou o estado oxidativo dos peixes,
com a dieta Gmix-ibericus a aumentar a eficiência de utilização do alimento em 25%, enquanto a dieta
Gmix-niger afetou negativamente o crescimento dos peixes. Numa outra abordagem, fungos marinhos
foram isolados de algas frescas e a sua aplicação em FES de C. tomentosum, U. rigida e GBP foi avaliada.
Duas espécies fúngicas foram identificadas: Aspergillus flavus IC3 produziu um extrato rico em enzimas
através da FES de GBP, enquanto o fungo Stemphylium vesicarium IU4 aumentou o teor de proteína da
U. rígida fermentada. Por último, foi aplicado um pré-tratamento hidrotérmico seguido de hidrólise
enzimática à alga C. tomentosum para produzir um hidrolisado rico em açúcares, utilizado como meio
de cultura para o crescimento de A. ibericus. Obteve-se uma biomassa com 28% proteína, potencialmente
aplicável em rações.To sustain the expansion of the aquaculture industry, the demand for environmentally sustainable
and cost-effective ingredients for aquafeed is increasing. Seaweeds are a potential resource to be included
in aquafeed, due to their richness in valuable nutrients, and no competition with terrestrial plants for land
and freshwater uses. However, their polysaccharide content impairstheir inclusion in aquafeed, therefore,
the bioprocessing of this biomass through a biotechnological approach such as solid-state fermentation
(SSF) can be advantageous to increase seaweeds' nutritional value. Thus, firstly, the potential of five
seaweeds (Gracilaria sp., Porphyra dioica, Codium tomentosum, Ulva rigida, and Alaria esculenta) as
substratesfor SSF with the filamentous fungi (Aspergillus ibericus MUM 03.49 and Aspergillus niger CECT
2915) was evaluated. The SSF of U. rigida with both fungi resulted in the maximum xylanase and β glucosidase activities, while its carbohydrate content decreased by 54% and 62% after SSF with A. ibericus
and A. niger, respectively. In addition, Gelidium corneum by-product after agar extraction (GBP) was also
used in SSF with the same fungi, but no differences were observed in polysaccharide content as well as
low enzymatic activity. This substrate was mixed with sunflower cake (1:1 ratio; Gmix), and SSF of the
mixture improved enzyme production and protein content of the fermented solid, thus this mixture was
selected to be included in diets for European seabass: 10% of the mixture unfermented (Gmix diet) or
fermented by A. ibericus (Gmix-ibericus diet) or A. niger (Gmix-niger diet). Overall, Gmix or Gmix-ibericus
diets did not compromise European seabass performance or oxidative status, with the Gmix-ibericus diet
enhancing feed utilization efficiency by 25%, while the Gmix-niger diet negatively affected fish growth
performance. In another approach, marine fungi were isolated from fresh seaweeds, and their application
in SSF of C. tomentosum, U. rigida, and GBP was evaluated. Two fungal species were identified:
Aspergillus flavus IC3 produced an enzyme-rich extract through SSF of GBP, while Stemphylium
vesicarium IU4 increased the protein content of fermented U. rigida. Lastly, a hydrothermal pretreatment
followed by enzymatic hydrolysis was applied to the seaweed C. tomentosum to produce a sugar-rich
hydrolysate that was used as a culture medium for the growth of A. ibericus. A biomass with 28% protein
was obtained, with potential aquafeed application.À Fundação para a Ciência e Tecnologia (FCT) pela atribuição da bolsa de doutoramento (SFRH/BD/143614/2019), ao projeto SPO3 (POCI-01-0145-FEDER-030377) e ao projeto MB4AQUA (2022.06587.PTDC)
Wildlife conservation using UAV and LoRa network
No full textDissertação de mestrado em Network Engineering and Telematics ServicesMany animal species are on the verge of extinction due to poaching and changes in land use, such as
the destruction of forest areas to the detriment of agriculture, logging, and the construction of new towns
and cities. Therefore, regular monitoring of animal populations is necessary to ensure the protection of
wildlife, especially when pressure on animals is high, and conservation management requires reliable
and up-to-date data on land use, the size of animal populations, and the distribution of resources in highly
variable ecosystems. In this context, we would like to contribute to the process of automating conventional
methods, taking advantage of the Internet of Things (IoT) paradigm, which has evolved rapidly in recent
years, and emerging digital technologies such as Low-Power Wide-Area Networks (LPWAN) and the rapid
growth of Unmanned Aerial Vehicles (UAVs), also known as Drones.
Therefore, this study proposes a wildlife monitoring system based on acoustic detection, using LoRa
networks assisted by UAVs that act as mobile gateways to collect data from sensors on the ground. This
aims to contribute to the protection of fauna in Angola by helping forest rangers to obtain actionable data
from their operations.
To check that the proposed system works correctly, tests were carried out in a simulation environment,
verifying the correct transmission of data from the sensors to the data center. However, this technique
provides a more sustainable and scalable monitoring method, minimizing human effort.Muitas espécies animais estão à beira da extinção devido à caça furtiva e às mudanças no uso da terra,
como a destruição de áreas florestais em detrimento da agricultura, exploração madeireira e a construção
de novas vilas e cidades. Portanto, é necessário monitorizar regularmente as populações animais para
assegurar a proteção da vida selvagem, especialmente quando a pressão sobre os animais é elevada, e
a gestão da conservação requer dados fiáveis e atualizados sobre a utilização dos solos, a dimensão das
populações animais e a distribuição dos recursos em ecossistemas altamente variáveis.
Neste contexto, gostaríamos de contribuir para o processo de automatização dos métodos conven cionais, aproveitando o paradigma da Internet das Coisas (IoT), que evoluiu rapidamente nos últimos
anos, e das tecnologias digitais emergentes, como as redes de área alargada de baixa potência (LPWAN)
e o rápido crescimento dos veículos aéreos não tripulados (UAV), também conhecidos como drones. Por tanto, este estudo propõe um sistema de monitorização da vida selvagem baseado na detecção acústica,
usando redes LoRa assistidas por UAVs que atuam como gateways móveis para coletar dados dos nós
no solo. Isso visa contribuir para a proteção da fauna em Angola, ajudando os guardas florestais a obter
dados acionáveis das suas operações.
Para verificar o correto funcionamento do sistema proposto, foram realizados testes em ambiente de
simulação, verificando a correta transmissão dos dados dos sensores para o sistema central. No entanto,
esta técnica fornece um método de monitoramento mais sustentável e escalável reduzindo no mínimo o
esforço humano
Stakeholder and Communication Management at the Portuguese Project Management Observatory
No full textDissertação de mestrado em Gestão de Projetos de EngenhariaEsta dissertação inicia-se com um enquadramento, na qual se apresenta a metodologia utilizada para
analisar a gestão de stakeholders e a comunicação no âmbito do Observatório Português de Gestão de
Projetos®
(OPGP). Nesta etapa, define-se o contexto da investigação, delineando os objetivos de
investigação e os métodos utilizados para os atingir.
Posteriormente, procede-se a uma revisão detalhada da literatura, seguindo as diretrizes das boas
práticas e dos manuais da especialidade. Nesta revisão, aborda-se, de forma singular, a gestão de
stakeholders e a gestão da comunicação, explorando os princípios, conceitos e melhores práticas
associados a cada um destes tópicos fundamentais da gestão de projetos. Esta análise de detalhe
permite compreender as complexidades subjacentes à gestão de stakeholders e à comunicação em
projetos, fornecendo uma base sólida para a investigação subsequente.
Este estudo tem como objetivo responder a duas perguntas de investigação (RQ – Research Questions)
fundamentais: RQ1: "Quais os processos e ferramentas indicadas para gerir os stakeholders e a
comunicação no OPGP?"; RQ2: "Como aumentar o número de organizações e o seu grau de
envolvimento e compromisso com o OPGP?". Após a revisão de literatura, utilizou-se para recolha de
dados um inquérito por questionário e entrevistas, possibilitando a obtenção de dados relevantes - 141
respostas ao questionário, contendo um conjunto de perguntas fechadas e abertas e 12 entrevistas
semiestruturadas. Os dados dos questionários foram analisados, quantitativamente, através do software
SPSS, enquanto os dados das entrevistas foram analisados qualitativamente, com recurso à análise de
conteúdo e no software MAXQDA. Estas análises permitiram a obtenção de informação relevante para
formular as principais conclusões.
Com base nos resultados, este estudo pretende proporcionar uma compreensão abrangente das práticas
de gestão de stakeholders e de comunicação no contexto do OPGP. Espera-se que as conclusões
fundamentadas contribuam para uma apreciação mais profunda das dinâmicas de gestão de projetos e
de comunicação no âmbito do OPGP – único na Europa, e que tenham aplicação prática na definição
das estratégias e ferramentas a aplicar no OPGP.This master thesis begins with an introduction, presenting the methodology used to analyze stakeholder
and communication management within the scope of the Portuguese Project Management Observatory®
(OPGP). In this phase, the research context is defined, outlining the research objectives and the methods
employed to achieve them.
Subsequently, a detailed literature review is conducted, following the guidelines of best practices and
specialized manuals. This review singularly addresses stakeholder management and communication
management, exploring the principles, concepts, and best practices associated with each of these
fundamental project management topics. This detailed analysis enables an understanding of the
complexities underlying stakeholder and communication management in projects, providing a solid
foundation for subsequent research.
The study aims to answer two fundamental research questions (RQ – Research Questions): RQ1: "What
processes and tools are recommended for managing stakeholders and communication in the OPGP?";
RQ2: "How can the number of organizations and their level of involvement and commitment to the OPGP
be increased?". After the literature review, a questionnaire survey and interviews were used for data
collection, facilitating the acquisition of relevant data - 141 questionnaire responses, containing a set of
closed and open-ended questions, and 12 semi-structured interviews. The questionnaire data were
quantitatively analyzed using the SPSS software, while the interview data were qualitatively analyzed using
content analysis and the MAXQDA software. These analyses provided relevant information to formulate
the main conclusions.
Based on the results, this study aims to provide a comprehensive understanding of stakeholder and
communication management practices in the context of the OPGP. It is expected that the informed
conclusions will contribute to a deeper appreciation of project management and communication
dynamics within the OPGP – unique in Europe, and have practical application in defining strategies and
tools for the OPGP
Applicability of the design thinking process to the development of capstone project proposals
No full textThe purpose of this paper is to present an empirical study that explores how design thinking can be applied to develop ideas for capstone projects in undergraduate engineering programs. Action research was the research method used in this study. The collected data consisted of students’ project proposals, grades, classroom observations, and focus group findings. This study has two levels of implications: 1) for the practice of educators, as they can adjust the approach developed to help undergraduate engineering students find a potential idea for a viable and relevant capstone project; 2) for research, thereby adding to the ongoing discussion on exploring the design thinking process as a conceptual structure that provides a basis for dealing with difficult situations and solving complex problems in undergraduate courses.FCT - Fundação para a Ciência e a Tecnologia(UIDB/00319/2020
Youth activism and the call for generational responsibility in climate politics
No full textYoung climate activists have been instrumental in stirring the climate debate, employing a range of actions and discursive approaches to urge swift action from governments and society. A large body of literature on youth studies, sociology, education, communication, and environmental sciences shows how these activists have actively worked to surpass entrenched discursive and imaginative constraints within the climate debate by demanding their voices to be heard, and by offering a new vigour to the concept of climate crisis. By challenging established norms and systems, youth activism has, to a certain extent, inspired alternative visions for the future where their voices could be recognized and included. This chapter provides an overview of literature examining how youth-led climate action may have expanded the boundaries of discourse within climate politics. Our analysis underscores one of the most relevant contributions of youth activism: the moral imperative of generational responsibility, which has catalysed the politicization of the present moment. Continuously excluded from political processes, youth demand broader societal participation to formulate solutions and alternatives, indirectly proposing ways to reconfiguring climate politics as more democratic and pluralistic.This work received funding from the Fundação para a Ciência e a Tecnologia for the research project Climate futures and just transformations: Young people’s narratives and political imaginaries (http://doi.org/10.54499/PTDC/COM-OUT/7669/2020
High temperature performance of cement mortars with incorporation of PEG-based form-stable Phase Change Materials
No full textThe integration of a phase change material in mortar promises to improve thermal comfort and reduce energy
consumption. Assessing mortar behavior under diverse temperature conditions, especially high ones encountered in unforeseen disasters or accidents, is essential for evaluating their reliability and resilience in safeguarding building safety and longevity. This research examines the behavior of cement-based mortar, containing a sustainable PCM incorporated into porous aggregates from processing waste, when exposed to different temperatures (i.e., 20, 200, 600 ◦C). A comprehensive study on the physical properties of the cement-based mortar formulations (with and without the phase change materials) has been conducted, revealing an increase in the flexural and compressive strengths for a temperature exposure of 200ºC, due to the acceleration of the hydration process of the binder. However, a decrease in flexural and compressive strengths, as well as adhesion, for the temperature exposure of 600ºC was observed, due to the microcracks developed due the high thermal gradient. This behavior is observable even in mortars that do not contain any phase change material. Thermal cycle test of the phase change material involved in this work (i.e., Polyethylene-glycol of molecular weight 1000) has been carried out: stable melting and crystallization temperatures were recorded with a maximum enthalpy variation of 5 %.This work was supported by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Centre for Territory, Environment and Construction (CTAC) under reference UIDB/04047/2020 and by PON Ricerca e Innovazione 2014–2020 Risorse ReactEu - DM 1062/2021 Azione IV.4, “Dottorati e contratti di ricerca su tematiche dell’innovazione” and Azione IV.6, “Contratti di ricerca su tematiche green”