Produção de hidrogénio através da gasificação da biomassa

A procura de uma forma limpa de combustível, aliada à crescente instabilidade de preços dos combustíveis fósseis verificada nos mercados faz com que o hidrogénio se torne num combustível a considerar devido a não resultar qualquer produto poluente da sua queima e de se poder utilizar, por exemplo, desperdícios florestais cujo valor de mercado não está inflacionado por não pertencer à cadeia alimentar humana. Este trabalho tem como objetivo simular o processo de gasificação de biomassa para produção de hidrogénio utilizando um gasificador de leito fluidizado circulante. O oxigénio e vapor de água funcionam como agentes gasificantes. Para o efeito usou-se o simulador de processos químicos ASPEN Plus. A simulação desenvolvida compreende três etapas que ocorrem no interior do gasificador: pirólise, que foi simulada por um bloco RYIELD, combustão de parte dos compostos voláteis, simulada por um bloco RSTOIC e, por fim, as reações de oxidação e gasificação do carbonizado “char”, simuladas por um bloco RPLUG. Os valores de rendimento dos compostos após a pirólise, obtidos por uma correlação proposta por Gomez-Barea, et al. (2010), foram os seguintes: 20,33% “char”, 22,59% alcatrão, 36,90% monóxido de carbono, 16,05%m/m dióxido de carbono, 3,33% metano e 0,79% hidrogénio (% em massa). Como não foi possível encontrar valores da variação da composição do gás à saída do gasificador com a variação da temperatura, para o caso de vapor de água e oxigénio, optou-se por utilizar apenas vapor na simulação de forma a comparar os seus valores com os da literatura. Às temperaturas de 700, 770 e 820ºC, para um “steam-to-biomass ratio”, (SBR) igual a 0,5, os valores da percentagem molar de monóxido de carbono foram, respetivamente, 56,60%, 55,84% e 53,85%, os valores de hidrogénio foram, respetivamente, 17,83%, 18,25% e 19,31%, os valores de dióxido de carbono foram, respetivamente, 16,40%, 16,85% e 17,93% e os valores de metano foram, respetivamente, 9,00%, 8,95% e 8,83%. Os valores da composição à saída do gasificador, à temperatura de 820ºC, para um SBR de 0,5 foram: 53,85% de monóxido de carbono, 19,31% de hidrogénio, 17,93% de dióxido de carbono e 8,83% de metano (% em moles). Para um SBR de 0,7 a composição à saída foi de 54,45% de monóxido de carbono, 19,01% de hidrogénio, 17,59% de dióxido de carbono e 8,87% de metano. Por fim, quando SBR foi igual a 1 a composição do gás à saída foi de 55,08% de monóxido de carbono, 18,69% de hidrogénio, 17,24% de dióxido de carbono e 8,90% de metano. Os valores da composição obtidos através da simulação, para uma mistura de ar e vapor de água, ER igual a 0,26 e SBR igual a 1, foram: 34,00% de monóxido de carbono, 14,65% de hidrogénio, 45,81% de dióxido de carbono e 5,41% de metano. A simulação permitiu-nos ainda dimensionar o gasificador e determinar alguns parâmetros hidrodinâmicos do gasificador, considerando que a reação “water-gas shift” era a limitante, e que se pretendia obter uma conversão de 95%. A velocidade de operação do gasificador foi de 4,7m/s e a sua altura igual a 0,73m, para um diâmetro de 0,20m.

Oral health in the family health strategy: a change of practices or semantics diversionism

OBJECTIVE:To evaluate public health dentistry practices of two different family health models. METHODS: Qualitative study conducted with data obtained from focus groups consisting of 58 dentists working in the Family Health Strategy for at least three years between August-October, 2006. The Paideia Family Health Approach was used in the city of Campinas and the Oral Health Initiative as part of the Family Health Strategy was implemented in the city of Curitiba, Southeastern and Southern Brazil, respectively. Data was analyzed using the hermeneutic-dialectic method. Analysis indicators were employed to indicate backwardness, stagnation or progress in oral health practices effective from the implementation of the strategies referred. The indicators used were: work process; interdisciplinary approach; territorialization; capacity building of human resources; health promotion practices; and responsiveness to users' demands. RESULTS: There was progress in user access to services, humanization of health care, patient welcoming and patient-provider relationship. The results related to health promotion practices, territorialization, interdisciplinary approach and resource capacity building indicated a need for technical and operational enhancements in both cities. CONCLUSIONS: Both models have brought about important advances in terms of increased access to services and humanization of health care. Universal access to oral health at all levels of complexity was not achieved in both cities studied. Local health managers and oral health program coordinators must bring more weight to bear in the arena that defines public policy priorities.

O Balanced Scorecard como instrumento de gestão estratégica e a sua implementação na 3S, Solvay Shared Services

Mestrado em Contabilidade e Gestão das Instituições Financeiras

Análise da divulgação ambiental das empresas cotadas no PSI20 e no IBEX35 nos anos de 2010 e 2011

Mestrado em Contabilidade

Exporting "failure": why research from rich countries may not benefit the developing world

The '10/90 gap' was first highlighted by the Global Forum for Health Research. It refers to the finding that 90% of worldwide medical research expenditure is targeted at problems affecting only 10% of the world's population. Applying research results from the rich world to the problems of the poor may be a tempting, potentially easy and convenient solution for this gap. This paper had the objective of presenting arguments that such an approach runs the risk of exporting failure. Health interventions that are shown to be effective in the specific context of a Western industrialized setting will not necessarily work in the developing world.

Epidemiologic transition in northern Angola: discussion of cumulative results from CISA (Health Research Centre of Angola)

The 41 years of armed conflict (1961 to 2002) resulted in a poor development of the health care and education infrastructures, and forced the relocation of people to safer places, namely major urban cities like Luanda. This phase was characterized by typical demographic, nutritional and epidemiological profiles. With the end of this period Angola has been repeatedly ranked as one of the three fastest growing economies in the world, and along with the social stabilization and globalization, the country is facing the introduction of new medical technologies, improvement of health sys-tems and services, better access to them, and overall better quality of life. These changes could also be translating into socio-cultural, demographic and nutritional changes which in turn may leading to changes in the epidemiological profile of the country. Thus, the emergence of non-communicable diseases are likely to become an increasingly im-portant public health problem in Angola. Also, considering that several infectious diseases persist, our weakened health system will have to face a double burden. Thus, disease surveillance data on non-communicable diseases to determine their prevalence and impact, along with the major behavioural risk factors like consumption of tobacco, alcohol, diets and physical inactivity are urgently needed.

Gestão da segurança e saúde no trabalho em trabalhos de beneficiação rodoviária: perfil de autoestrada e a aplicação dos princípios gerais da prevenção à fase de execução da obra

Mestrado em Segurança e Higiene no Trabalho

Motivar é a chave do sucesso

Mestrado em Gestão e Empreendedorismo

Antitumor activity of hierridin B, a cyanobacterial secondary metabolite found in both filamentous and unicellular marine strains

Cyanobacteria are widely recognized as a valuable source of bioactive metabolites. The majority of such compounds have been isolated from so-called complex cyanobacteria, such as filamentous or colonial forms, which usually display a larger number of biosynthetic gene clusters in their genomes, when compared to free-living unicellular forms. Nevertheless, picocyanobacteria are also known to have potential to produce bioactive natural products. Here, we report the isolation of hierridin B from the marine picocyanobacterium Cyanobium sp. LEGE 06113. This compound had previously been isolated from the filamentous epiphytic cyanobacterium Phormidium ectocarpi SAG 60.90, and had been shown to possess antiplasmodial activity. A phylogenetic analysis of the 16S rRNA gene from both strains confirmed that these cyanobacteria derive from different evolutionary lineages. We further investigated the biological activity of hierridin B, and tested its cytotoxicity towards a panel of human cancer cell lines; it showed selective cytotoxicity towards HT-29 colon adenocarcinoma cells.

Exploring bioactive properties of marine cyanobacteria Isolated from the Portuguese coast: high potential as a source of anticancer compounds

The oceans remain a major source of natural compounds with potential in pharmacology. In particular, during the last few decades, marine cyanobacteria have been in focus as producers of interesting bioactive compounds, especially for the treatment of cancer. In this study, the anticancer potential of extracts from twenty eight marine cyanobacteria strains, belonging to the underexplored picoplanktonic genera, Cyanobium, Synechocystis and Synechococcus, and the filamentous genera, Nodosilinea, Leptolyngbya, Pseudanabaena and Romeria, were assessed in eight human tumor cell lines. First, a crude extract was obtained by dichloromethane:methanol extraction, and from it, three fractions were separated in a Si column chromatography. The crude extract and fractions were tested in eight human cancer cell lines for cell viability/toxicity, accessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactic dehydrogenase release (LDH) assays. Eight point nine percent of the strains revealed strong cytotoxicity; 17.8% showed moderate cytotoxicity, and 14.3% assays showed low toxicity. The results obtained revealed that the studied genera of marine cyanobacteria are a promising source of novel compounds with potential anticancer activity and highlight the interest in also exploring the smaller filamentous and picoplanktonic genera of cyanobacteria.

Licensing endogenous cost-reduction in a differentiated Stackelberg model

In this paper we consider a differentiated Stackelberg model, when the leader firm engages in an R&D process that gives an endogenous cost-reducing innovation. The aim is to study the licensing of the cost-reduction by a two-part tariff. By using comparative static analysis, we conclude that the degree of the differentiation of the goods plays an important role in the results. We also do a direct comparison between our model and Cournot duopoly model.

Research practice development for nuclear medicine technologists: an innovative experience

Introduction - European nuclear medicine technologist’s education is delivered by Higher Education Institutions and students obtain a grade of Bachelor of Sciences (BSc), during which they are initiated to research during their studies. Once BSc nuclear medicine technologists are in professional practice, they have very few opportunities to develop a real research experience and they rather become passive users than active contributors the growth of scientific knowledge in nuclear medicine. Aim - To describe and discuss an innovative educational and professional experience aimed in strengthen research knowledge, skills and competencies of former nuclear medicine technologists student in the context of an international mobility stay.

Flexibility in a Stackelberg leadership with differentiated goods

We study the effects of product differentiation in a Stackelberg model with demand uncertainty for the first mover. We do an ex-ante and ex-post analysis of the profits of the leader and of the follower firms in terms of product differentiation and of the demand uncertainty. We show that even with small uncertainty about the demand, the follower firm can achieve greater profits than the leader, if their products are sufficiently differentiated. We also compute the probability of the second firm having higher profit than the leading firm, subsequently showing the advantages and disadvantages of being either the leader or the follower firm.

Antitumor activity of hierridin B, a cyanobacterial secondary metabolite found in both filamentous and unicellular marine strains

Cyanobacteria are widely recognized as a valuable source of bioactive metabolites. The majority of such compounds have been isolated from so-called complex cyanobacteria, such as filamentous or colonial forms, which usually display a larger number of biosynthetic gene clusters in their genomes, when compared to free-living unicellular forms. Nevertheless, picocyanobacteria are also known to have potential to produce bioactive natural products. Here, we report the isolation of hierridin B from the marine picocyanobacterium Cyanobium sp. LEGE 06113. This compound had previously been isolated from the filamentous epiphytic cyanobacterium Phormidium ectocarpi SAG 60.90, and had been shown to possess antiplasmodial activity. A phylogenetic analysis of the 16S rRNA gene from both strains confirmed that these cyanobacteria derive from different evolutionary lineages. We further investigated the biological activity of hierridin B, and tested its cytotoxicity towards a panel of human cancer cell lines; it showed selective cytotoxicity towards HT-29 colon adenocarcinoma cells.

Projeto de uma instalação de climatização para um edifício hospitalar

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecância