Alkaline-earth aluminosilicate-based glass and glass-ceramic sealants for functional applications

The planar design of solid oxide fuel cell (SOFC) is the most promising one due to its easier fabrication, improved performance and relatively high power density. In planar SOFCs and other solid-electrolyte devices, gas-tight seals must be formed along the edges of each cell and between the stack and gas manifolds. Glass and glass-ceramic (GC), in particular alkaline-earth alumino silicate based glasses and GCs, are becoming the most promising materials for gas-tight sealing applications in SOFCs. Besides the development of new glass-based materials, new additional concepts are required to overcome the challenges being faced by the currently existing sealant technology. The present work deals with the development of glasses- and GCs-based materials to be used as a sealants for SOFCs and other electrochemical functional applications. In this pursuit, various glasses and GCs in the field of diopside crystalline materials have been synthesized and characterized by a wide array of techniques. All the glasses were prepared by melt-quenching technique while GCs were produced by sintering of glass powder compacts at the temperature ranges from 800−900 ºC for 1−1000 h. Furthermore, the influence of various ionic substitutions, especially SrO for CaO, and Ln2O3 (Ln=La, Nd, Gd, and Yb), for MgO + SiO2 in Al-containing diopside on the structure, sintering and crystallization behaviour of glasses and properties of resultant GCs has been investigated, in relevance with final application as sealants in SOFC. From the results obtained in the study of diopside-based glasses, a bilayered concept of GC sealant is proposed to overcome the challenges being faced by (SOFCs). The systems designated as Gd−0.3 (in mol%: 20.62MgO−18.05CaO−7.74SrO−46.40SiO2−1.29Al2O3 − 2.04 B2O3−3.87Gd2O3) and Sr−0.3 (in mol%: 24.54 MgO−14.73 CaO−7.36 SrO−0.55 BaO−47.73 SiO2−1.23 Al2O3−1.23 La2O3−1.79 B2O3−0.84 NiO) have been utilized to realize the bi-layer concept. Both GCs exhibit similar thermal properties, while differing in their amorphous fractions, revealed excellent thermal stability along a period of 1,000 h. They also bonded well to the metallic interconnect (Crofer22APU) and 8 mol% yttrium stabilized zirconium (8YSZ) ceramic electrolyte without forming undesirable interfacial layers at the joints of SOFC components and GC. Two separated layers composed of glasses (Gd−0.3 and Sr−0.3) were prepared and deposited onto interconnect materials using a tape casting approach. The bi-layered GC showed good wetting and bonding ability to Crofer22APU plate, suitable thermal expansion coefficient (9.7–11.1 × 10–6 K−1), mechanical reliability, high electrical resistivity, and strong adhesion to the SOFC componets. All these features confirm the good suitability of the investigated bi-layered sealant system for SOFC applications.

Ecological and biotechnological potential of sponge microbiome

Marine sponges harbor microbial communities of immense ecological and biotechnological importance. Recently, they have been focus of heightened attention due to the wide range of biologically active compounds with potential application, particularly, in chemical, cosmetic and pharmaceutical industries. However, we still lack fundamental knowledge of their microbial ecology and biotechnological potential. The development of high-throughput sequencing technologies has given rise to a new range of tools that can help us explore the biotechnological potential of sponges with incredible detail. Metagenomics, in particular, has the power to revolutionize the production of bioactive compounds produced by unculturable microorganisms. It can offer the identification of biosynthetic genes or gene clusters that can be heterologously expressed on a cultivable and suitable host. This review focus on the exploration of the biotechnological potential of sponge-associated microorganisms, and integration of molecular approaches, whose increasing efficiency can play an essential role on achieving a sustainable source of natural products.

Development of a sustainable method for the extraction of lycopene and β-carotene from food wastes

The main objective of the present work is the study of a profitable process not only in the extraction and selective separation of lycopene and β-carotene, two compounds present in tomato, but also in its potential application to food industry wastes. This is one of the industries that produce larger amounts of wastes, which are rich in high value biomolecules with great economic interest. However, the conventional methods used to extract this kind of compounds are expensive which limits their application at large scale. Lycopene and βcarotene are carotenoids with high commercial value, known for their antioxidant activity and benefits to human health. Their biggest source is tomato, one of the world’s most consumed fruits, reason for which large quantities of waste is produced. This work focuses on the study of diverse solvents with a high potential to extract carotenoids from tomato, as well as the search for more environmentally benign solvents than those currently used to extract lycopene and β-carotene from biomass. Additionally, special attention was paid to the creation of a continuous process that would allow the fractionation of the compounds for further purification. Thus, the present work started with the extraction of both carotenoids using a wide range of solvents, namely, organic solvents, conventional salts, ionic liquids, polymers and surfactants. In this stage, each solvent was evaluated in what regards their capacity of extraction as well as their penetration ability in biomass. The results collected showed that an adequate selection of the solvents may lead to the complete extraction of both carotenoids in one single step, particularly acetone and tetrahydrofuran were the most effective ones. However, the general low penetration capacity of salts, ionic liquids, polymers and surfactants makes these solvents ineffective in the solid-liquid extraction process. As the organic solvents showed the highest capacity to extract lycopene and βcarotene, in particular tetrahydrofuran and acetone, the latter solvent used in the development process of fractionation, using to this by strategic use of solvents. This step was only successfully developed through the manipulation of the solubility of each compound in ethanol and n-hexane. The results confirmed the possibility of fractionating the target compounds using the correct addition order of the solvents. Approximately, 39 % of the β-carotene was dissolved in ethanol and about 64 % of lycopene was dissolved in n-hexane, thus indicating their separation for two different solvents which shows the selective character of the developed process without any prior stage optimization. This study revealed that the use of organic solvents leads to selective extraction of lycopene and β-carotene, allowing diminishing the numerous stages involved in conventional methods. At the end, it was possible to idealize a sustainable and of high industrial relevance integrated process, nevertheless existing the need for additional optimization studies in the future.

A interface carboneto de silício-solução aquosa e o enchimento por barbotina

Neste trabalho estudaram-se as interfaces carboneto de silício-solução aquosa e carbono-solução aquosa, com vista a uma melhor compreensão dos processos de floculaçáo e desfloculaçáo de suspensões de cada um daqueles materiais e de suas misturas. Os pós foram caracterizados por recurso a técnicas de sedimentação, microscopia electrónica de varrimento, difracçáo de raios-X, análises térmicas, espectroscopia de infra-vermelhos e picnometria de hélio. As suspensões foram caracterizadas por técnicas de microelectroforese, sedimentação e reologia. Estudou-se a influência de algumas variáveis mais importantes do processo de enchimento por barbotina como, por exemplo, o mecanismo e o grau de estabilização das suspensões, a concentração de sólidos, a distribuição granulométrica das partículas, e o tempo de envelhecimento das suspensões, na estrutura das partículas em suspensão e nas características dos corpos conformados por enchimento por barbotina. A cinética deste processo foi estudada sob o efeito de pressão aplicada e relacionada com a estrutura das partículas em suspensão e com a microstrutura dos corpos em verde. Estudaram-se os mecanismos da segregação de tamanhos de partículas em suspensão que ocorre durante o processo de enchimento por barbotina devidos aos efeitos da gravidade e da obstrução do bolo pelas partículas finas. Discutiram-se os domínios das variáveis do processo em que cada um daqueles efeitos é dominante e propôs-se um novo modelo para o fenómeno da segregação por efeito de obstrução capaz de interpretar os resultados observados neste trabalho e os encontrados na literatura. Estabeleceram-se correlações estreitas entre as variáveis do processo de enchimento por barbotina, a microestrutura dos corpos conformados e o seu comportamento durante a etapa da secagem. Procurou ainda avaliar-se a capacidade do enchimento por barbotina para preparar materiais compósitos de carboneto de silício e carbono com características adequadas para a sinterizaçáo reactiva.

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Caracterização química e bioquímica dos frutos de ARBUTUS UNEDO L. e de RUBUS FRUTICOSUS AGG.: contribuição para a sua valorização

Dissertação mest., Agricultura sustentável, Universidade do Algarve, 2007

Ecologia e demografia de uma população de águia de Bonelli Aquila Fasciata em meio florestal

Tese de dout., Ecologia, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2008

Pesquisa de antifúngicos de origem vegetal

Dissertação mest., Engenharia Biológica, Universidade do Algarve, 2009

Modelling underwater acoustic noise as a tool for coastal management

Dissertação de Mestrado, Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Modelos de avaliação de hipotecas comerciais: soluções analíticas

Tese de dout., Gestão, Faculdade de Economia, Universidade do Algarve, 2005

Efeitos da alta densidade e jejum nas modificações do metabolismo intermediário do pargo (Pagrus pagrus)

Dissertação mest., Engenharia Biológica, Universidade do Algarve, 2008

Estudos sobre aproveitamento biotecnológico da quitina produzida por organismos marinhos

Dissertação mest., Biotecnologia, Universidade do Algarve, 2008

Estudo zooarqueológico de comunidades islâmicas do Algarve

Dissertação de mest., Arqueologia (Teoria e Métodos da Arqueologia), Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2011

Produção de um agente de controlo biológico recorrendo a subprodutos da indústria agro-alimentar

Dissertação de mest., Biologia Molecular e Microbiana, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Dinâmica da matéria particulada em suspensão na plataforma continental minhota e sua relação com a cobertura sedimentar

Tese de dout., Ciências do Mar, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2001