Degradação fotocatalítica de petróleo e seus derivados através da utilização de nanopartículas de dióxido de titânio puro e misturado com óxido de grafeno reduzido

Dissertação de mestrado integrado em Engenharia de Materiais

Effect of chitosan-Aloe vera coating on postharvest quality of blueberry (Vaccinium corymbosum) fruit

The present study was carried out to evaluate the effect of chitosan-based edible coatings with Aloe vera extract on the postharvest blueberry fruit quality during storage at 5 °C. Firstly, A. vera fractions (pulp and liquid) were extracted from leaves and evaluated in terms of antifungal and antioxidant capacities. The choice of the most adequate chitosan and A. vera fraction concentrations to be incorporated in coating formulation was made based on the wettability of the corresponding coating solutions. Coatings with 0.5% (w/v) chitosan + 0.5% (w/v) glycerol + 0.1% (w/v) Tween 80 + 0.5% (v/v) A. vera liquid fraction presented the best characteristics to uniformly coat blueberry surface. Physico-chemical (i.e., titratable acidity, pH, weight loss) and microbiological analyses of coated blueberries (non-inoculated or artificially inoculated with Botrytis cinerea) were performed during 25 d. Microbiological growth and water loss levels were approximately reduced by 50% and 42%, respectively, in coated blueberries after 25 d compared to uncoated blueberries. After 15 d, weight loss values were 6.2% and 3.7% for uncoated and chitosanA. vera coated blueberries, respectively. Uncoated fruits presented mold contamination after 2 d of storage (2.0 ± 0.32 log CFU g1), whilst fruits with chitosan-based coatings with A. vera presented mold contamination only after 9 d of storage (1.3 ± 0.35 log CFU g1). Overall, coatings developed in this study extend blueberries shelf-life for about 5 d, demonstrating for the first time that the combination of chitosan and A. vera liquid fraction as edible coating materials has great potential in expanding the shelf-life of fruits.

Layer-by-layer technique to developing functional nanolaminate films with antifungal activity

The layer-by-layer (LbL) deposition method was used to build up alternating layers (five) of different polyelectrolyte solutions (alginate, zein-carvacrol nanocapsules, chitosan and chitosan-carvacrol emulsions) on an aminolysed/charged polyethylene terephthalate (A/C PET) film. These nanolaminated films were characterised by contact angle measurements and through the determination of water vapour (WVTR) and oxygen (O2TR) transmission rates. The effect of active nanolaminated films against the Alternaria sp. and Rhizopus stolonifer was also evaluated. This procedure allowed developing optically transparent nanolaminated films with tuneable water vapour and gas properties and antifungal activity. The water and oxygen transmission rate values for the multilayer films were lower than those previously reported for the neat alginate or chitosan films. The presence of carvacrol and zein nanocapsules significantly decreased the water transmission rate (up to 40 %) of the nanolaminated films. However, the O2TR behaved differently and was only improved (up to 45 %) when carvacrol was encapsulated, i.e. nanolaminated films prepared by alternating alginate with nanocapsules of zein-carvacrol layers showed better oxygen barrier properties than those prepared as an emulsion of chitosan and carvacrol. These films containing zein-carvacrol nanocapsules also showed the highest antifungal activity (30 %), which did not significantly differ from those obtained with the highest amount of carvacrol, probably due to the controlled release of the active agent (carvacrol) from the zein-carvacrol nanocapsules. Thus, this work shows that nanolaminated films prepared with alternating layers of alginate and zein-carvacrol nanocapsules can be considered to improve the shelf-life of foodstuffs.

Processamento e caracterização de compósitos de Ti-HAP para aplicações biomédicas

Dissertação de mestrado integrado em Engenharia de Materiais

Holistic approach, tourism

Holistic refers to something that emphasizes the whole and the interdependence of its parts. It can be conceptualized as interdisciplinary: the claim that most social and economic phenomena cannot be fully understood or explained without adopting an approach that goes beyond the aims of a single scientific discipline.

Escritas da utopia na literatura contemporânea – da utopia à distopia

Tese de Doutoramento em Ciências da Literatura (Especialidade em Literatura Comparada)

[Recensão a] Basílio, Margarida (2013). Formação e classes de palavras no português do Brasil

[Excerto] Antes de mais, impõe-se este esclarecimento: estamos na presença da 1.ª reimpressão da 3.ª edição (a 1.ª é de 2004) do livro em epígrafe, e a razão de só agora o estar a recensear (sabia contudo da sua existência há já alguns anos) tem simplesmente a ver com o facto de não há muito me ter chegado às mãos e, sobretudo, de só muito recentemente ter tido a oportunidade de o ler como deve ser, isto é, reflexivamente. Trata-se de um pequeno grande texto de uma especialista na matéria (Margarida Basílio, professora titular da Pontifícia Universidade Católica do Rio de Janeiro), que conheço há longos anos de outros, de que destacaria Teoria lexical (São Paulo: Ática, 1987) e Estruturas lexicais do português: uma abordagem gerativa (Petrópolis: Vozes, 1980). Pequeno, é claro, só no número de páginas: nem sequer chega às cem (noventa e cinco, contabilizadas já as duas com as referências bibliográficas). Grande, deveras, no que diz respeito à temática e de modo particular ao seu tratamento: uma descrição de pendor didático dos padrões gerais e dos principais processos de formação de palavras na variedade brasileira do português. (...)

Study of grapevine solute transporters involved in berry quality. A biochemical and molecular approach

Tese de Doutoramento em Biologia de Plantas

Carbon materials as new generation of new electron shuttles for the anaerobic degradation of environmental xenobiotics

Tese de Doutoramento em Engenharia Química e Biológica

Neurocognitive profile and cognitive intervention in Alzheimer's disease

Tese de Doutoramento em Psicologia (Especialidade de Psicologia Clínica)

Synthesis of iminosugars through diastereo/enantioselective diels-alder cycloaddition

Tese de Doutoramento em Ciências (Especialidade em Química)

Development of procedures for the design, optimization and manufacturing of customized orthopaedic and trauma implants: Geometrical/anatomical modelling from 3D medical imaging

Tese de Doutoramento (Programa Doutoral em Engenharia Biomédica)

Nanotechnological approaches using curcumin and Withania somnifera: neuroprotection and antimicrobial activities

Tese de Doutoramento em Biologia de Plantas

Sucesso escolar e percursos vocacionais na adolescência: variáveis pessoais e contextuais

Tese de Doutoramento Ciências da Educação (Especialidade em Psicologia da Educação)

Cathepsin D protects colorectal cancer cells from acetate-induced apoptosis through autophagy-independent degradation of damaged mitochondria

Acetate is a short-chain fatty acid secreted by Propionibacteria from the human intestine, known to induce mitochondrial apoptotic death in colorectal cancer (CRC) cells. We previously established that acetate also induces lysosome membrane permeabilization in CRC cells, associated with release of the lysosomal protease cathepsin D (CatD), which has a well-established role in the mitochondrial apoptotic cascade. Unexpectedly, we showed that CatD has an antiapoptotic role in this process, as pepstatin A (a CatD inhibitor) increased acetate-induced apoptosis. These results mimicked our previous data in the yeast system showing that acetic acid activates a mitochondria-dependent apoptosis process associated with vacuolar membrane permeabilization and release of the vacuolar protease Pep4p, ortholog of mammalian CatD. Indeed, this protease was required for cell survival in a manner dependent on its catalytic activity and for efficient mitochondrial degradation independently of autophagy. In this study, we therefore assessed the role of CatD in acetate-induced mitochondrial alterations. We found that, similar to acetic acid in yeast, acetate-induced apoptosis is not associated with autophagy induction in CRC cells. Moreover, inhibition of CatD with small interfering RNA or pepstatin A enhanced apoptosis associated with higher mitochondrial dysfunction and increased mitochondrial mass. This effect seems to be specific, as inhibition of CatB and CatL with E-64d had no effect, nor were these proteases significantly released to the cytosol during acetate-induced apoptosis. Using yeast cells, we further show that the role of Pep4p in mitochondrial degradation depends on its protease activity and is complemented by CatD, indicating that this mechanism is conserved. In summary, the clues provided by the yeast model unveiled a novel CatD function in the degradation of damaged mitochondria when autophagy is impaired, which protects CRC cells from acetate-induced apoptosis. CatD inhibitors could therefore enhance acetate-mediated cancer cell death, presenting a novel strategy for prevention or therapy of CRC.