Comunidades de práticas: relações, responsabilidades e oportunidades para uma educação para a sustentabilidade

Esta comunicação surge no âmbito do “Projeto Outgoing - Crianças, natureza e cultura em relação”, que visa fortalecer as relações com o meio natural e cultural, contribuindo para um sentido de pertença à Terra com potencial (trans)formador e emancipatório das práticas educativas para a sustentabilidade, desde a infância. Nesta comunicação deste estudo, ainda numa fase inicial, iremos apresentar a sua conceção metodológica. A formação de educadores/as deve desenvolver competências de colaboração e de pensamento crítico, consideradas essenciais para a tomada de posição e decisão relativas à sustentabilidade (UNESCO, 2017). Situamos a dimensão de formação contínua de educadores/as infância na perspetiva de desenvolvimento e formação permanente na área da Educação para a Sustentabilidade, em contexto prático e colaborativo. Deste modo, assume-se a perspetiva teórica da teoria social da aprendizagem proposta por Wenger (1998), reconhecendo-se o papel da participação para a construção de conhecimento profissional, valorizando a sua dimensão reflexiva e social. A comunidade de prática concretiza estes pressupostos, através do envolvimento voluntário dos seus membros, a partilha e discussão de experiências e conhecimentos relacionados com a prática em educação para a sustentabilidade na infância. No campo metodológico, reconhecendo-se a natureza dinâmica, holística e interativa da realidade a estudar, pretende-se compreendê-la tal como percecionada pelos participantes, mas orientada para a mudança. O desenvolvimento do estudo assenta na construção de uma Comunidade de Prática (CoP) com 15 educadores/as de infância (dos concelhos de Setúbal, Lisboa e Évora) e os respetivos grupos de crianças, onde, numa perspetiva cíclica, se discutem problemas, conceitos, perspetivas teóricas, estratégias e se planificam as atividades Outgoing (atividades de imersão-afetação em contextos naturais e culturais) e o modo como se escuta as crianças sobre a sua experiência nestas atividades. Numa modalidade de investigação-ação-formação, iremos conhecer o ponto de vista dos educadores/as de infância envolvidos, numa perspetiva relacional e formativa da Educação para a Sustentabilidade na Infância e analisar o modo como os educadores/as constroem conhecimento e se desenvolvem profissionalmente no contexto social da CoP, numa modalidade de estudo de caso, de cariz participativo e em co-design

Improving Colloidal Stability of Sepiolite Suspensions: Effect of the Mechanical Disperser and Chemical Dispersant

To allow the use of fibrous-like clays, as sepiolite, in different applications, their disaggregation and the formation of stable suspensions are crucial steps to enhance their performance significantly, e.g., in cellulose nanofibrils/clay composite formulations, enabling an adequate mixture of the matrix and filler individual components. Three distinct physical treatments of dispersion (magnetic stirring, high-speed shearing, and ultrasonication) and four different chemical dispersants (polyacrylate, polyphosphate, carboxymethylcellulose, and alginate, all in the form of sodium salts) were tested to improve the dispersibility and the formation of stable suspensions of sepiolite. Two sepiolite samples from the same origin but with different pre-treatments were evaluated. The particle size and suspension stability were evaluated by dynamic light scattering, zeta potential measurements and optical microscopy. Additionally, the sepiolite samples were initially characterized for their mineralogical, chemical, and morphologic properties. Of the three physical dispersion treatments tested, the ultrasonicator typically produced more stable suspensions; on the other hand, the biopolymer carboxymethylcellulose showed a higher ability to produce stable suspensions, being, however, a smaller particle size obtained when polyphosphate was used. Remarkably, 47 out of 90 prepared suspensions of sepiolite stayed homogeneous for at least three months after their preparation. In sum, the combination of a high energy dispersing equipment with an appropriate dispersing agent led to stable suspensions with optimal properties to be used in different applications, like in the composite production.The authors acknowledge Luís Maria, Eirini Potsi, and Solange Magalhães for the help in the preparation of a few suspensions, particle size and zeta potential measurements.info:eu-repo/semantics/publishedVersio

Stabilization of Palygorskite Aqueous Suspensions Using Bio-Based and Synthetic Polyelectrolytes

Palygorskite is a natural fibrous clay mineral that can be used in several applications, for which colloidal stability in aqueous suspensions is a key point to improve its performance. In this study, methods of magnetic stirring, high-speed shearing, and ultrasonication, as well as different chemical dispersants, combined with these methods, namely carboxymethylcellulose, alginate, polyphosphate, and polyacrylate, were used to improve the dispersibility and the formation of stable suspensions of palygorskite in different conditions of pH. The stability and particle size of suspensions with a low concentration of palygorskite were evaluated by visual inspection, optical and electron microscopy, dynamic light scattering, and zeta potential measurements. Moreover, the palygorskite used in this work was initially characterized for its mineralogical, chemical, physical, and morphological properties. It was found that more stable suspensions were produced with ultrasonication compared to the other two physical treatments, with magnetic stirring being inefficient in all tested cases, and for higher pH values (pH of 12 and pH of 8, the natural pH of the clay) when compared to lower pH values (pH of 3). Remarkably, combined with ultrasonication, carboxymethylcellulose or in a lesser extent polyphosphate at near neutral pH allowed for the disaggregation of crystal bundles of palygorskite into individualized crystals. These results may be helpful to optimize the performance of palygorskite in several domains where it is applied.The present research was supported by the R&D project titled “FILCNF-New generation of composite films of cellulose nanofibrils with mineral particles as high strength materials with gas barrier properties” (PTDC/QUI-OUT/31884/2017, CENTRO 01-0145-FEDER-031884), Strategic Research Centre Project UIDB00102/2020, and Techn & Art (UID/05488/2018) funded by the Fundação para a Ciência e Tecnologia (FCT) and FEDER.info:eu-repo/semantics/publishedVersio

Correlation between flocculation and adsorption of cationic polyacrylamides on precipitated calcium carbonate

The study of each stage of the flocculation process is essential to better understand and predict flocculation mechanisms. The adsorption of cationic polyacrylamide derivatives (C-PAM) onto precipitated calcium carbonate (PCC) has been investigated systematically as a function of the C-PAM characteristics including molar mass, chain architecture, and charge density. The adsorption results show that, for C-PAM of similar molar mass, highly branched architectures reach the equilibrium faster than linear C-PAM. Similarly, the flocculation rate is higher for the branched C-PAM, which may be indicative of the predominance of the bridging mechanism. In terms of the molar mass, lower molar mass leads to lower adsorption rates and slower flocculation. Adsorption isotherms of C-PAM onto precipitated calcium carbonate could be described by the Langmuir isotherm model. The maximum amount of C-PAM that adsorbs on the particle surface as a monolayer, obtained from adsorption tests through the Langmuir isotherm linear fit, could be correlated with the structure of the aggregates, obtained from flocculation experiments. Moreover, a good correlation was obtained between the adsorption results and the kinetics of the first stage of the flocculation process dominated by particle aggregation

The scaling of genetic diversity in a changing and fragmented world

Most species do not live in a constant environment over space or time. Their environment is often heterogeneous with a huge variability in resource availability and exposure to pathogens or predators, which may affect the local densities of the species. Moreover, the habitat might be fragmented, preventing free and isotropic migrations between local sub-populations (demes) of a species, making some demes more isolated than others. For example, during the last ice age populations of many species migrated towards refuge areas from which re-colonization originated when conditions improved. However, populations that could not move fast enough or could not adapt to the new environmental conditions faced extinctions. Populations living in these types of dynamic environments are often referred to as metapopulations and modeled as an array of subdivisions (or demes) that exchange migrants with their neighbors. Several studies have focused on the description of their demography, probability of extinction and expected patterns of diversity at different scales. Importantly, all these evolutionary processes may affect genetic diversity, which can affect the chance of populations to persist. In this chapter we provide an overview on the consequences of fragmentation, long-distance dispersal, range contractions and range shifts on genetic diversity. In addition, we describe new methods to detect and quantify underlying evolutionary processes from sampled genetic data.Laboratoire d’Excellence (LABEX) entitled TULIP: (ANR-10-LABX-41)

Pre-treatment of industrial olive oil mill effluent using low dosage health-friendly cationic polyelectrolytes

Olive oil production involves a significant annual release of industrial olive oil mill effluent (OME) to the environment. These discharges bring serious environmental problems since they are extremely hazardous for the aquatic environment due to their organic matter and high turbidity levels. The present study comprises the development of new, hydrophobically modified, cationic flocculants directed to oily effluents application. A health-friendly formulation was used in their synthesis process, performed by inverse-emulsion. In particular, Poly(AAm-MAPTAC) was synthesized in two different polymer compositions and, as well, with the presence of a hydrophobic monomer (Poly(AAm-MAPTAC-SMA)) at several compositions up to 8wt%. The obtained polyelectrolytes were characterized in terms of final composition, hydrodynamic diameter, zeta potential and molecular weight. Their flocculation performance was evaluated in an industrial oily effluent from an olive oil mill. Results revealed that the hydrophobic modification improves noticeably the flocculation performance of cationic polyelectrolytes in the treatment of olive oil mill effluents. In the best conditions, it was possible to achieve 90% turbidity reduction, 47% COD removal and 34% total solids removal with only 53mg/L of flocculant. Moreover, 79% of turbidity was reduced after addition of 13mg/L

Acacia wood fractionation using deep eutectic solvents: extraction, recovery, and characterization of the different fractions

The selective extraction and recovery of different lignocellulosic molecules of interest from forestry residues is increasing every day not only to satisfy the needs of driving a society toward more sustainable approaches and materials (rethinking waste as a valuable resource) but also because lignocellulosic molecules have several applications. For this purpose, the development of new sustainable and ecologically benign extraction approaches has grown significantly. Deep eutectic solvents (DESs) appear as a promising alternative for the processing and manipulation of biomass. In the present study, a DES formed using choline chloride and levulinic acid (ChCl:LA) was studied to fractionate lignocellulosic residues of acacia wood (Acacia dealbata Link), an invasive species in Portugal. Different parameters, such as temperature and extraction time, were optimized to enhance the yield and purity of recovered cellulose and lignin fractions. DESs containing LA were found to be promising solvent systems, as the hydrogen bond donor was considered relevant in relation to lignin extraction and cellulose concentration. On the other hand, the increase in temperature and extraction time increases the amount of extracted material from biomass but affects the purity of lignin. The most promising DES system, ChCELA in a ratio of 1:3, was found to not significantly depolymerize the extracted lignin, which presented a similar molecular weight to a la-aft lignin. Additionally, the P-31 NMR results revealed that the extracted lignin has a high content of phenolic OH groups, which favor its reactivity. A mixture of ChCl:LA may be considered a fully renewable solvent, and the formed DES presents good potential to fractionate wood residues.info:eu-repo/semantics/publishedVersio

Oral colonization by yeasts in HIV-positive patients in Brazil

INTRODUCTION: In HIV-infected patients, colonization of the oral cavity by potential pathogenic yeast may lead to development of systemic fungemia. We evaluated the prevalence of yeast in the oral cavity of Brazilian HIV-positive patients and verified whether or not the species characterized were enzymatically active. Furthermore, the species identified were tested for their susceptibility to antifungal treatment. METHODS: Patient saliva and oropharyngeal candidiasis samples were collected from 60 seropositive HIV patients and identified by the API20C system. Enzymatic activity was evaluated by the production of proteinase and phospholipase. Susceptibility to antifungal treatments were determined using the broth microdilution method. RESULTS: the most commonly isolated species were C. albicans (51.56%) followed by non-albicans Candida species (43.73%), Trichosporon mucoides (3.12%) and Kodamaea ohmeri (1.56%). Oral colonization by association of different species was observed in 42% of the patients. Enzymatic activity was verified in most of species isolated, except for C. glabrata, C. lusitaniae and C. guilliermondii. Resistance to Fluconazole and Amphotericin B was observed in isolates of C. albicans, C. glabrata, C. parapsilosis, C. krusei, and K. ohmeri. CONCLUSION: HIV-positive patients are orally colonized by single or multiple species of yeast that are occasionally resistant to Fluconazole or Amphotericin B.INTRODUÇÃO: Em pacientes infectados pelo HIV, a colonização da cavidade bucal por leveduras patogênicas pode levar ao desenvolvimento de fungemias. No presente estudo, avaliamos a prevalência de leveduras na cavidade bucal de pacientes HIV-positivos e verificamos se as espécies isoladas foram enzimaticamente ativas. Além disso, as espécies identificadas foram testadas quanto à suscetibilidade a antifúngicos. MÉTODOS: Amostras de saliva e de candidose orofaríngea foram coletadas de 60 pacientes soropositivos para HIV e identificados pelo sistema API20C. A atividade enzimática foi avaliada pela produção de proteinase e fosfolipase. A suscetibilidade a antifúngicos foi determinada utilizando o método de microdiluição em caldo. RESULTADOS: As espécies mais comumente isoladas foram C. albicans (51,56%), seguido por espécies de Candida não-albicans (43,73%), Trichosporon mucoides (3,12%) e Kodamaea ohmeri (1,56%). A colonização bucal por associação de diferentes espécies foi observada em 42% dos pacientes. A atividade enzimática foi verificada na maioria das espécies isoladas, com exceção de C. glabrata, C. lusitaniae e C. guilliermondii. Resistência ao fluconazol e anfotericina B foi observada em isolados de C. albicans, C. glabrata, C. parapsilosis, C. krusei, e K. ohmeri. CONCLUSÃO: Os pacientes HIV-positivos são colonizados por espécies únicas ou múltiplas de levedura que ocasionalmente são resistentes ao fluconazol ou anfotericina B

Filmes de Celulose Nanofibrilada com Incorporação de Minerais como Substitutos de Plásticos em Embalagens Alimentares: Potencialidades e Dificuldades

Celuloses nanofibriladas (CNF) são nanomateriais com propriedades promissoras para produção de embalagens alimentares, sendo substitutos lógicos de polímeros de base petroquímica, especificamente plásticos. Contudo, estes materiais apresentam algumas limitações, como o seu elevado custo. A combinação de CNF com minerais argilosos representa uma excelente abordagem para a produção de materiais de elevado valor acrescentado com custos aceitáveis, possibilitando ainda a melhoria de algumas propriedades dos materiais, como por exemplo o efeito barreira a gases. Para a produção de filmes compósitos podem ser seguidas duas estratégias: evaporação de solvente ou filtração seguida de prensagem a quente. Os filmes obtidos por filtração apresentam propriedades mecânicas superiores às dos obtidos por evaporação de solvente e são preparados mais rapidamente. Assim, esta técnica apresentase como a mais apropriada e eficiente para a produção de filmes compósitos com boas propriedades mecânicasN/

Filmes de celulose nanofibrilada com incorporação de minerais: uma nova geração de materiais para embalagens alimentares e eletrónica impressa

O trabalho de investigação foi realizado no âmbito do projeto “FILCNF-New generation of composite films of cellulose nanofibrils with mineral particles as high strength materials with gas barrier properties” (PTDC/QUI-OUT/31884/2017, CENTRO 01-0145-FEDER-031884), financiado pelo Programa Operacional Regional do Centro na sua componente FEDER e pela Fundação para a Ciência e Tecnologia (FCT). Agradece-se ainda ao RAIZ pelo fornecimento da pasta branqueada de Eucalyptus globulus e pelo acesso ao homogeneizador de alta pressão, assim como ao centro de investigação CIEPQPF (UIDB00102/2020) pelas condições disponibilizadas.info:eu-repo/semantics/publishedVersio