Optimization of antioxidants extraction from coffee silverskin, aroasting by-product, having in view a sustainable process

Coffee silverskin is a major roasting by-product that could be valued as a source of antioxidant compounds. The effect of the major variables (solvent polarity, temperature and extraction time) affecting the extraction yields of bioactive compounds and antioxidant activity of silverskin extracts was evaluated. The extracts composition varied significantly with the extraction conditions used. A factorial experimental design showed that the use of a hydroalcoholic solvent (50%:50%) at 40 °C for 60 min is a sustainable option to maximize the extraction yield of bioactive compounds and the antioxidant capacity of extracts. Using this set of conditions it was possible to obtain extracts containing total phenolics (302.5 ± 7.1 mg GAE/L), tannins (0.43 ± 0.06 mg TAE/L), and flavonoids (83.0 ± 1.4 mg ECE/L), exhibiting DPPHradical dot scavenging activity (326.0 ± 5.7 mg TE/L) and ferric reducing antioxidant power (1791.9 ± 126.3 mg SFE/L). These conditions allowed, in comparison with other “more effective” for some individual parameters, a cost reduction, saving time and energy.

Evolution and biogenesis of microtubule-derived structures

Dissertação apresentada para obtenção do grau de Doutor em Biologia Celular pelo Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa

Text classification using compression-based dissimilarity measures

Arguably, the most difficult task in text classification is to choose an appropriate set of features that allows machine learning algorithms to provide accurate classification. Most state-of-the-art techniques for this task involve careful feature engineering and a pre-processing stage, which may be too expensive in the emerging context of massive collections of electronic texts. In this paper, we propose efficient methods for text classification based on information-theoretic dissimilarity measures, which are used to define dissimilarity-based representations. These methods dispense with any feature design or engineering, by mapping texts into a feature space using universal dissimilarity measures; in this space, classical classifiers (e.g. nearest neighbor or support vector machines) can then be used. The reported experimental evaluation of the proposed methods, on sentiment polarity analysis and authorship attribution problems, reveals that it approximates, sometimes even outperforms previous state-of-the-art techniques, despite being much simpler, in the sense that they do not require any text pre-processing or feature engineering.

Regulation of PLK4 levels and activity to ensure centriole number control

Dissertation presented to obtain a Ph.D degree in Cellular Biology

Development of integrated separation processes with green solvents

Dissertação para obtenção do Grau de Doutor em Química Sustentável

Membrane structural changes support the involvement of mitochondria in the bile salt-induced apoptosis of rat hepatocytes

Clin Sci (Lond). 2002 Nov;103(5):475-85

Tauroursodeoxycholic acid prevents Bax-induced membrane perturbation and cytochrome C release in isolated mitochondria

Biochemistry, 2003, 42 (10), pp 3070–3080 DOI: 10.1021/bi026979d

The Role of Actin-Capping Protein and Src signalling in tissue growth and apoptosis during Drosophila wing development

Dissertation presented to obtain the Ph.D degree in Developmental Biology

Centriole elimination in Drosophila melanogaster oogenesis

Dissertation presented to obtain the Ph.D degree in Cellular Biology

The role of Grainy head in epithelial tissue growth

Part of the results of this thesis was presented in the following meetings: Susana Ponte, Lara Carvalho, Inês Cristo and António Jacinto. The role of Grainy head in epithelial tissue growth. Drostuga 2013. Faro, Portugal, January 3rd 2014 [poster] Susana Ponte, Lara Carvalho, Inês Cristo and António Jacinto. The role of Grainy head in epithelial tissue growth. Drostuga 2014. Tomar, Portugal, September 5th-6th 2014 [poster]

Leishmanicidal activity and cytotoxicity of compounds from two Annonacea species cultivated in Northeastern Brazil

INTRODUCTION: Visceral leishmaniasis is endemic in 88 countries, with a total of 12 million people infected and 350 million at risk. In the search for new leishmanicidal agents, alkaloids and acetogenins isolated from leaves of Annona squamosa and seeds of Annona muricata were tested against promastigote and amastigote forms of Leishmania chagasi. METHODS: Methanol-water (80:20) extracts of A. squamosa leaves and A. muricata seeds were extracted with 10% phosphoric acid and organic solvents to obtain the alkaloid and acetogenin-rich extracts. These extracts were chromatographed on a silica gel column and eluted with a mixture of several solvents in crescent order of polarity. The compounds were identified by spectroscopic analysis. The isolated compounds were tested against Leishmania chagasi, which is responsible for American visceral leishmaniasis, using the MTT test assay. The cytotoxicity assay was evaluated for all isolated compounds, and for this assay, RAW 264.7 cells were used. RESULTS: O-methylarmepavine, a benzylisoquinolinic alkaloid, and a C37 trihydroxy adjacent bistetrahydrofuran acetogenin were isolated from A. squamosa, while two acetogenins, annonacinone and corossolone, were isolated from A. muricata. Against promastigotes, the alkaloid showed an IC50 of 23.3 µg/mL, and the acetogenins showed an IC50 ranging from 25.9 to 37.6 µg/mL; in the amastigote assay, the IC50 values ranged from 13.5 to 28.7 µg/mL. The cytotoxicity assay showed results ranging from 43.5 to 79.9 µg/mL. CONCLUSIONS: These results characterize A. squamosa and A. muricata as potential sources of leishmanicidal agents. Plants from Annonaceae are rich sources of natural compounds and an important tool in the search for new leishmanicidal therapies.

Modulation of electrical stimulation applied to human physiology and clinical diagnostic

The use, manipulation and application of electrical currents, as a controlled interference mechanism in the human body system, is currently a strong source of motivation to researchers in areas such as clinical, sports, neuroscience, amongst others. In electrical stimulation (ES), the current applied to tissue is traditionally controlled concerning stimulation amplitude, frequency and pulse-width. The main drawbacks of the transcutaneous ES are the rapid fatigue induction and the high discomfort induced by the non-selective activation of nervous fibers. There are, however, electrophysiological parameters whose response, like the response to different stimulation waveforms, polarity or a personalized charge control, is still unknown. The study of the following questions is of great importance: What is the physiological effect of the electric pulse parametrization concerning charge, waveform and polarity? Does the effect change with the clinical condition of the subjects? The parametrization influence on muscle recruitment can retard fatigue onset? Can parametrization enable fiber selectivity, optimizing the motor fibers recruitment rather than the nervous fibers, reducing contraction discomfort? Current hardware solutions lack flexibility at the level of stimulation control and physiological response assessment. To answer these questions, a miniaturized, portable and wireless controlled device with ES functions and full integration with a generic biosignals acquisition platform has been created. Hardware was also developed to provide complete freedom for controlling the applied current with respect to the waveform, polarity, frequency, amplitude, pulse-width and duration. The impact of the methodologies developed is successfully applied and evaluated in the contexts of fundamental electrophysiology, psycho-motor rehabilitation and neuromuscular disorders diagnosis. This PhD project was carried out in the Physics Department of Faculty of Sciences and Technology (FCT-UNL), in straight collaboration with PLUX - Wireless Biosignals S.A. company and co-funded by the Foundation for Science and Technology.

Estudo da toponímia do Município de Saurimo – Princípios para a harmonização da grafia

O presente trabalho oferece contribuições no campo da Onomástica, ciência que se encarrega do estudo dos nomes próprios, na vertente toponímica relativa ao estudo dos nomes geográfico, num enfoque etnolinguístico que apresenta as motivações toponímicas e a grafia correcta do topónimo na fonologia da língua do denominador. Atendendo às diferentes grafias que apresentam os nomes de lugares em diversas partes do território angolano, nas línguas em que estes nomes se apresentam, esta dissertação centra-se na análise dos principais motivadores de variação gráfica dos topónimos do município de Saurimo, apresentados em sua maioria na língua Cokwe em contacto com o Português. Apresenta-se a história e fixação da etnia Cokwe, os fundamentos morfofonológicos do Ucokwe, algumas influências sofridas pelo Português, diferenças com o Português, classificações taxonómicas, essenciais para análise e reformulação da grafia dos topónimos escritos, na sua maioria, em Ucokwe.

Vocabulário de base no ensino primário em Angola

O nosso trabalho tem como objectivo apresentar uma organização de um Vocabulário de Base no Ensino Primário em Angola, numa perspectiva de ensino e aprendizagem do Português, em contexto angolano, com vista à contribuição e melhoria das estratégias do ensino e aprendizagem do vocabulário, não só em sala de aula, como também a sua aplicação em materiais didácticos, como em dicionários de aprendizagem. Apresentámos, de uma forma sucinta, a organização e o contexto de desenvolvimento dos Sistema de Educação de Angola, com a finalidade de fazer um enquadramento dos planos de estudo do Ensino Primário. Foram importantes as abordagens sobre os conceitos básicos de Lexicologia, Lexicografia, léxico, cultura, vocabulário, Lexicultura. Usámos o software Hyperbase como metodologia para o levantamento, selecção e organização dos vocábulos nos manuais escolares. O software serviu para análise dos dados dos textos, de modo a propor um dicionário de aprendizagem, conforme o modelo apresentado no final do trabalho.

Antroponímia da língua Kimbundu em Malanje

A Antroponímia da Língua Kimbundu em Malanje é um tema importante da sociedade angolana. Desde a colonização aos nossos dias, adoptamos padrões culturais provenientes do Ocidente. O direito de ter um nome na língua local foi e tem sido rejeitado, nas conservatórias e nos registos civis e, substituídos pelos nomes europeus, bíblicos e pela fusão de nomes, cuja origem e significado não nos é acessível. Diante desta problemática, ninguém pode permanecer indiferente, razão pela qual, o presente trabalho propõe-se responder à exigência de investir na sobrevivência da identidade cultural. A ocidentalização dos nomes desencadeada por alguns funcionários do Ministério da Justiça, em colaboração com alguns pais, está a causar mudanças nos valores locais, o que significa o início do desmoronamento da língua e da cultura Kimbundu. Reconhecemos a diversidade das culturas, mas nenhuma é superior à outra. Auguramos que este trabalho contribuía para a aceitação e a valorização dos nomes nas línguas angolanas de origem africana e, sobretudo, trazer de volta a identidade do povo Kimbundu.