Compósitos CNTs/biocerâmico para a estimulação elétrica óssea in situ

The present thesis aims to develop a biocompatible and electroconductor bone graft containing carbon nanotubes (CNTs) that allows the in situ regeneration of bone cells by applying pulsed external electrical stimuli. The CNTs were produced by chemical vapor deposition (CVD) by a semi-continuous method with a yield of ~500 mg/day. The deposition parameters were optimised to obtain high pure CNTs ~99.96% with controlled morphologies, fundamental requisites for the biomedical application under study. The chemical functionalisation of CNTs was also optimised to maximise their processability and biocompatibility. The CNTs were functionalised by the Diels-Alder cycloaddition of 1,3-butadiene. The biological behaviour of the functionalised CNTs was evaluated in vitro with the osteoblastic cells line MG63 and in vivo, by subcutaneous implantation in rats. The materials did not induce an expressed inflammatory response, but the functionalised CNTs showed a superior in vitro and in vivo biocompatibility than the non-functionalised ones. Composites of ceramic matrix, of bioglass (Glass) and hydroxyapatite (HA), reinforced with carbon nanotubes (CNT/Glass/HA) were processed by a wet approach. The incorporation of just 4.4 vol% of CNTs allowed the increase of 10 orders of magnitude of the electrical conductivity of the matrix. In vitro studies with MG63 cells show that the CNT/Glass/HA composites guarantee the adhesion and proliferation of bone cells, and stimulate their phenotype expression, namely the alkaline phosphate (ALP). The interactions between the composite materials and the culture medium (α-MEM), under an applied electrical external field, were studied by scanning vibrating electrode technique. An increase of the culture medium electrical conductivity and the electrical field confinement in the presence of the conductive samples submerged in the medium was demonstrated. The in vitro electrical stimulation of MG63 cells on the conductive composites promotes the increase of the cell metabolic activity and DNA content by 130% and 60%, relatively to the non-stimulated condition, after only 3 days of daily stimulation of 15 μA for 15 min. Moreover, the osteoblastic gene expression for Runx2, osteocalcin (OC) and ALP was enhanced by 80%, 50% and 25%, after 5 days of stimulation. Instead, for dielectric materials, the stimulus delivering was less efficient, giving an equal or lower cellular response than the non-stimulated condition. The proposed electroconductive bone grafts offer exciting possibilities in bone regeneration strategies by delivering in situ electrical stimulus to cells and consequent control of the new bone tissue formation rate. It is expected that conductive smart biomaterials might turn the selective bone electrotherapy of clinical relevance by decreasing the postoperative healing times.

Codon ambiguities as a mechanism to alter the genetic code in Saccharomyces cerevisiae

Although the genetic code is generally viewed as immutable, alterations to its standard form occur in the three domains of life. A remarkable alteration to the standard genetic code occurs in many fungi of the Saccharomycotina CTG clade where the Leucine CUG codon has been reassigned to Serine by a novel transfer RNA (Ser-tRNACAG). The host laboratory made a major breakthrough by reversing this atypical genetic code alteration in the human pathogen Candida albicans using a combination of tRNA engineering, gene recombination and forced evolution. These results raised the hypothesis that synthetic codon ambiguities combined with experimental evolution may release codons from their frozen state. In this thesis we tested this hypothesis using S. cerevisiae as a model system. We generated ambiguity at specific codons in a two-step approach, involving deletion of tRNA genes followed by expression of non-cognate tRNAs that are able to compensate the deleted tRNA. Driven by the notion that rare codons are more susceptible to reassignment than those that are frequently used, we used two deletion strains where there is no cognate tRNA to decode the rare CUC-Leu codon and AGG-Arg codon. We exploited the vulnerability of the latter by engineering mutant tRNAs that misincorporate Ser at these sites. These recombinant strains were evolved over time using experimental evolution. Although there was a strong negative impact on the growth rate of strains expressing mutant tRNAs at high level, such expression at low level had little effect on cell fitness. We found that not only codon ambiguity, but also destabilization of the endogenous tRNA pool has a strong negative impact in growth rate. After evolution, strains expressing the mutant tRNA at high level recovered significantly in several growth parameters, showing that these strains adapt and exhibit higher tolerance to codon ambiguity. A fluorescent reporter system allowing the monitoring of Ser misincorporation showed that serine was indeed incorporated and possibly codon reassignment was achieved. Beside the overall negative consequences of codon ambiguity, we demonstrated that codons that tolerate the loss of their cognate tRNA can also tolerate high Ser misincorporation. This raises the hypothesis that these codons can be reassigned to standard and eventually to new amino acids for the production of proteins with novel properties, contributing to the field of synthetic biology and biotechnology.

Desenvolvimento e optimização de um meio de cultura para produção de biomassa algal em larga escala

Dissertação de mest., Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2009

Population model of the recent subtidal invasion of Sargassum muticum in southern Portugal

Dissertação de Mestrado, Biologia Marinha, Especialização em Ecologia e Conservação, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2007

Requisitos de ácido araquidónico em microdietas para larvas de dourada (Sparus aurata, L., 1758)

Dissertação mest., Aquacultura e Pescas, Universidade do Algarve, 2009

Estudo da deterioração da gamba Parapenaeus longirostris (Lucas, 1846)

Dissertação de mest., Tecnologia de Alimentos, Instituto Superior de Engenharia, Univ. do Algarve, 2010

Avaliação da inclusão de EVOCOL em dietas formuladas para juvenis de Linguado (Solea senegalensis, Kaup 1858)

Dissertação de mest., Biologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2010

Dietary biodiesel-derived crude glycerol in gilthead seabream juveniles (Sparus aurata): effects on growth performance and metabolism

In the European Union the turn towards renewable energy sources has increased the production of biodiesel from rapeseed oil, leaving glycerol (also known as glycerin) as a valuable by-product. For every litre of biodiesel produced, approximately 79 g of crude glycerol are generated. As the biodiesel production grows, the quantity of crude glycerol generated will be considerable and its utilization will become an urgent topic. One possibility is the use of crude glycerol on animal feeds. Glycerol has been evaluated as a dietary energy source for several farm animals, including fish. A study was undertaken to assess the effect of dietary biodiesel-derived glycerol (from rapeseed oil) on the overall growth performance, digestive capacity and metabolic nutrient utilization in juvenile gilthead seabream fed a low fishmeal level diet. Two practical diets were formulated to be isonitrogenous (crude protein, 45.4% DM), isolipidic (18.5% DM) and isoenergetic (gross energy, 21.3 kJ/g DM). The control diet (CTRL) was formulated with intermediate levels of marine-derived proteins (19%). In the same basal formulation, 5% glycerol (GLY) was incorporated at the expenses of wheat. Each dietary treatment was tested in triplicate tanks over 63 days, with 20 gilthead seabream (Sparus aurata), with a mean initial body weight (IBW) of 27.9  0.12 g. At the end of the trial, fish fed the CTRL diet reached a final body weight of 84.3  2.2 g (more than 3-fold increase of initial body weight). Fish fed the GLY diet showed a significantly higher (P<0.05) growth, expressed in terms of final body weight and specific growth rate. Voluntary feed intake was similar between the two treatments, but both feed efficiency and protein efficiency ratio were significantly improved (P<0.05) in fish fed the GLY diet. Dietary glycerol had no effect (P>0.05) on the apparent digestibility of protein. In comparison to the control treatment, dietary glycerol significantly improved (P<0.05) protein and fat retention. Activities of digestive enzymes were significantly affected by the various dietary treatments. Fish fed the GLY diet showed an enhanced activity of alkaline phosphatase (ALP) and pepsin, while activities of lipase and leucine-alanine peptidase (LAP) were little affected by dietary glycerol. Fish show the ability to use crude glycerol as a dietary energy substrate.

Cytogenetic and histological studies of the brook trout (Salvelinus fontinalis) x arctic charr (Salvelinus alpinus) hybrids

In aquaculture, application of fish hybrids has increased. This technique permits improvement of the fish production by providing specimens showing better growth rate when compared to the parental species. Indeed, sterile individuals are highly demanded because quite frequently parental fish mature before they reach the market size, which impairs their growth and decrease their economic value. Throughout the last years, the commercial and scientific interest in salmonids has increased rapidly, among them, the brook trout (Salvelinus fontinalis), Arctic charr (Salvelinus alpinus) are species that can be crossed to produce hybrids that might by cultured in the fish farms. In the present thesis, we have assessed chromosome numbers and evaluate gonadal sex in the brook trout X Arctic charr hybrid progenies. In our populations, the karyotype of the brook trout comprises 84 chromosomes: 16 bi-armed chromosomes (meta-submetacentric) and 68 one-armed chromosomes (telo-acrocentrics) and the chromosome arm number, NF= 100. Arctic charr karyotype shows variation related to the chromosome number (2n= 81-82) and stable chromosome arm number (NF= 100). 2n= 81 chromosomes consisted of 19 bi-armed and 62 one-armed chromosomes, while 2n= 82 karyotype was organized into 18 meta-submetacentric and 64 acrocentrics. The cytogenetic and histological analysis of the brook trout X Arctic charr hybrids (sparctics) was carried out to asses chromosome and chromosome arm number and gonadal sex of the studied specimens. Diploid chromosome number in the hybrids varied from 81 to 84 and individuals with 83 and 84 chromosomes were predominant. Most of the fish had chromosome arm number equal to 100. Robertsonian fusion in the Arctic charr and chromosome behaviour in the hybrid fish cells might lead to the observed variation in chromosome numbers in the hybrids. Among studied fish, 12 were males, 3 were females and 9 had intersex gonads. No correlation between chromosome number and disturbances in the gonadal development was found. This might suggest that intersex gonads might have been developed as a consequence of disturbances in the genetic sex determination process. Genetic sex determination acts properly in the parental species but in the hybrids this may not be as efficient.

Produção integrada em tanques de terra: "estudo comparativo da produção integrada de cinco espécies de Sparideos em sistema de policultivo simples e em sistema integrado com ostras e holotúrias" e "abordagem teórica de um estudo económico para IMTA"

O presente trabalho teve como objetivo avaliar a produção de peixes em dois diferentes sistemas de cultivo, policultivo e aquacultura multi-trófica integrada, tomando como referência o crescimento das espécies, o estudo patológico das brânquias e análise de conteúdo estomacal das espécies envolvidas no ensaio (Sparus aurata, Diplodus cervinus, D. puntazzo, D. sargus e D. vulgaris), e por fim foi feita uma abordagem teórica para identificar os custos envolvidos no sistema. Para realização do ensaio foram usados seis tanques, sendo dois tratamentos, em regime triplicado. Os resultados indicam uma boa adaptação dos peixes em ambos os sistemas. A biomassa inicial foi de 0,12 Kg.mˉ3, sendo formada por: 12% Sparus aurata (119,5g), 33% Diplodus puntazzo (134,7g), 45% D. sargus (90,3g), 3% D. cervinus (37,6g) e 7% D. vulgaris (93,1g) e em três tanques também com 42 Kg de Holoturia tubulosa, pepinos do mar, e 75 Kg de Crassostrea angulata, ostras. D. cervinus, D. vulgaris e D. sargus apresentaram baixa taxa de crescimento, ≤ 0,7g/dia, ambas as espécies, e Diplodus cervinus apresentou baixa taxa de sobrevivência em ambos os sistemas (57,8% poli cultivo e 73,3% IMTA). Diplodus puntazzo foi a espécie que melhor se adaptou ao sistema de policultivo simples. Sparus aurata foi a espécie que apresentou melhor taxa de crescimento e melhor taxa de sobrevivência nos dois sistemas. Os conteúdos alimentares apresentaram semelhança entre Diplodus cervinus, D. vulgaris e Sparus aurata, semelhantes também foram os itens alimentares identificados em D. sargus e D. puntazzo, entretanto a preferência alimentar das últimas espécies citadas são opostas as das três primeiras. S. aurata e D. puntazzo que apresentaram maior peso médio foram preferencialmente infestadas por Lamellodiscus spp.. Nas espécies com pesos médios inferiores, como D. cervinus, D. sargus e D. vulgaris foram maiores as infestações por Microcotyle spp.

Effect of temperature and prey in the biology of Scymnus subvillosus (Goeze) (Coleoptera: Coccinellidae)

Dissertação de Mestrado, Biotecnologia em Controlo Biológico, 18 de Dezembro de 2013, Universidade dos Açores.

O sistema de objectivos financeiros como metodologia e instrumento de mudança organizacional na gestão da PME

Numa economia global, em que é patente a importância das PME's, como motor da actividade económica constituída por uma realidade diversa, justifica-se o enquadrar do Teoria Financeira no contexto das PMEs, no âmbito da problemática do Sistema de Objectivos Financeiros. Como teor desta investigação, pretendemos não só sistematizar e desenvolver um corpo teórico relativo à problemática do sistema de objectivos financeiros, mas também analisar dentro do contexto das PME's, os principais atributos explicativos dos respectivos rnodelos. Utilizando como técnica o modelo de Curchill e Mullins, mostramos como o crescimento sustentado pode ser visto de uma forma dinâmica, destacando as suas potencialidades através da manipulação dos instrumentos de crescimento, e compreendermos a natureza e análise operacional dos objectivos financeiros e das suas consequências estratégicas, com o modelo de Donaldson.

Influência do tipo de chuteira em variáveis preditoras do risco de entorse lateral do tornozelo

Introdução: No futebol, a entorse lateral do tornozelo (ELT) destaca-se como sendo a lesão mais prevalente. Potenciada pela variedade de chuteiras disponíveis no mercado e pela crescente utilização de relvados sintéticos, a interação entre o terreno e o calçado tem assumido elevada relevância como fator de risco para a ELT. A maior incidência de lesões na 2ª parte do jogo traduz a necessidade do estudo dessa interação durante tarefas que envolvam fadiga. Objetivo: Estudar a influência das chuteiras em variáveis preditoras do risco de ELT em relvado sintético sob duas condições: sem e com fadiga dos músculos eversores do tornozelo Métodos: Foi utilizada uma amostra de atletas saudáveis. Todos os indivíduos realizaram 3 séries de 5 saltos médio-laterais uni-podálicos, cada uma com 1 de 3 modelos de chuteiras (Turf, Hard e Firm ground) em duas condições: sem e com fadiga induzida pelo dinamómetro isocinético. Durante a tarefa, a atividade eletromiográfica do longo e curto peroniais, o valor das forças de reação do solo e o movimento do retro-pé (plano frontal), foram recolhidos e usados para calcular variáveis cinemáticas (eversão/inversão do tornozelo, o deslocamento e velocidade do centro de pressão), cinéticas (taxa de crescimento das forças de reação do solo) e neuromusculares (tempo de ativação muscular dos peroniais). Resultados: À exceção do tempo de ativação do curto peronial com o modelo Hard ground (sem fadiga vs com fadiga (p=0,050), não foram identificadas diferenças estatisticamente significativas nas variáveis preditoras de lesão, entre chuteiras, nem entre as duas condições avaliadas. Conclusão: Para o teste funcional escolhido e executado por atletas saudáveis em sintético de 3ª geração, nenhuma das chuteiras apresenta maior risco de lesão (com e sem fadiga), tendo em conta as variáveis em estudo.

Avaliação de estruturas de madeira em serviço: caso de estudo da Ermida da Ascensão de Cristo

Dissertação para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Edificações

Análise da competitividade e desenvolvimento dos destinos turísticos da grande Lisboa e Oeste

Dissertação apresentada ao Instituto Politécnico do Porto para obtenção do Grau de Mestre em Gestão das Organizações, Ramo de Gestão de Empresas Orientada por: Professora Doutora Paula Odete Fernandes Professor Doutor Rui da Assunção Esteves Pimenta