Manufacture and characterization of a micro fuel-cell

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e ComputadoresHoje em dia, os equipamentos eletrónicos alimentados a bateria estão prestes a alcançar um ponto decisivo. Com o consumo energético dos componentes eletrónicos a seguir uma tendência decrescente e as baterias a aumentarem as suas capacidades, torna-se necessário procurar tecnologias alternativas para continuar a evoluir. As células de combustível são consideradas o próximo grande passo em termos de energia devido às suas várias vantagens, como a sua eficiência e a sua reduzida pegada ambiental. Com células de combustível é possível alcançar altas densidades energéticas mantendo uma elevada eficiência e um peso reduzido, algo essencial para pequenos equipamentos eletrónicos. No entanto, os elevados custos ainda impedem as células de combustível de se imporem nos vários mercados, desde dispositivos eletrónicos a sistemas de transporte. Esta dissertação pretende estudar a possibilidade de adaptar uma célula de combustível com membrana de troca iónica para a mais económica célula de combustível de metanol direto, assim como os vários circuitos auxiliares necessários para obter melhor desempenho na célula. A célula utilizada foi uma Horizon Mini PEM fuel cell. Estes circuitos são o sistema de abastecimento de combustível, que possibilita o correto fornecimento de combustível à célula, um sistema de gestão de energia, de forma a permitir a célula fornecer uma tensão de saída adequada para uso, e um sistema de controlo, para efetuar a gestão de todos os sistemas referidos anteriormente. Foram realizados vários testes, incluindo testes na célula, para tentar melhorar as suas capacidades. O sistema de abastecimento de combustível foi criado recorrendo a uma microbomba para fornecer o combustível e um conversor step-up para alimentá-la. Várias simulações foram realizadas numa primeira fase, com a implementação a ser efetuada em breadboard. O sistema de gestão de energia foi criado usando um conversor step-up da Linear Technology e componentes auxiliares, de forma a fornecer uma tensão de saída viável na célula, tendo sido implementado em circuito impresso. O sistema de controlo que deveria ter sido produzido tinha por base a plataforma Arduino e o microcontrolador Atmel ATMega 328.Nowadays, battery powered electronic devices are reaching a decisive point. With components energy consumption following a decrease tendency and batteries steadily improving their capacities, it is now necessary to look for other technologies to keep evolving. Fuel cells are considered the next big evolution for energy due to their great advantages, like efficiency and low environment impact. With fuel cells, it is possible to achieve high power density while keeping high efficiency and maintaining a low weight, which are key features to small electronic equipment. However, high prices are still keeping fuel cells from a breakthrough in all kinds of uses, from electronics to transport systems. This dissertation intends to study the possibility of adapting an existing proton exchange membrane fuel cell to the cheaper to use direct methanol fuel cell, as creating several auxiliary circuits that are essential to a better performance of the fuel cell. The used fuel cell was a Horizon Mini PEM fuel cell. These circuits are a fuel supply system, for a correct fuel supply to the cell, a power management system, to enable the cell to have an adequate voltage for external usage, and a microcontroller system, to control all the previously referred systems. Several tests were done, including performance tests for the fuel cell, to try to improve its capabilities. The fuel supply system was created using a micropump to provide fuel and a stepup converter to power it. Various simulations were made initially, and the first implementation was made on a breadboard. The power management system was created using an existing Linear Technology step-up and auxiliary components, to provide an eligible output voltage for the cell, being implemented on a printed circuit board. The control system was not produced, but was intended to using as basis the Arduino platform and the Atmel ATMega 328 microcontroller

Influence of heavy metals on nematode community structure in deteriorated soil by gold mining activities in Sibutad, southern Philippines

Ore mining is among the most environmentally destructive anthropogenic practices, particularly in developing countries. Correct assessment of its impacts on soil ecosystems requires an understanding of the response of soil food webs. Nematodes, often the most abundant invertebrates in soils, occupy various positions in food webs, and their assemblages are commonly used to reflect soil health. In October 2014, we collected soil samples from five sites of a small-scale mining area in Sibutad, southern Philippines, to assess the influence of mining activities on nematode assemblages. Two sites were considered undisturbed as there were no visible signs of mining, while the other three sites were disturbed. Nematodes were extracted live and identified to genus level using morphology -based identification. We analysed genus composition, genus and trophic diversity, and the life-history based maturity index. We measured soil environmental variables (pH, organic matter, granulometry and several heavy metals), and correlated variation in nematode genus composition to variation in these environmental factors. Small-scale mining activities had variable but generally non-significant impacts on soil properties, altered vegetation and caused increases in concentrations of Hg and Pb, but not consistently so in all impacted sites. The high patchiness in vegetation and heavy metal content were reflected in a high within-site variability of nematode assemblages. Total nematode abundance was significantly lowest in the most physically disturbed site, but not so in the most metal-polluted one, suggesting that abundance is not a good indicator of pollution status. Nematode genus composition significantly differed between disturbed and undisturbed sites. By contrast, only few differences between sites were found for diversity or maturity indices, demonstrating that genus composition was a better indicator of mining-related effects than many common indicator indices and highlighting that detailed assemblage analysis is required for a correct interpretation of moderate pollution effects on soil nematodes. Measured environmental variables together explained 60% of the variation in nematode assemblages in the area; the three 'single best' explanatory variables were the concentrations of Pb, Hg and N, but none of these by itself explained more than 8% of the variation in nematode data, while their combination explained 24%. Some genera of predacious and omnivorous nematodes, which are generally expected to be sensitive to both chemical pollution and physical disturbance (e.g., Ironus and Eudorylaimus), were most abundant in sites with elevated heavy metal concentrations, which can have repercussions for the interpretation of nematode-based indices such as the MI

The subplacenta of the red-rumped agouti (Dasyprocta leporina L)

BACKGROUND: Hystricognath rodents have a lobed placenta, comprising labyrinthine exchange areas and interlobular trophoblast. These correspond to the labyrinthine and spongy zones of other rodent placentae. Beneath them, however, is a structure unique to hystricognath rodents called the subplacenta. We here describe the subplacenta of the red-rumped agouti and examine the possible functional correlates of this structure. METHODS: Placentae were collected from early in midgestation to near term of pregnancy and examined by standard histological techniques, immunohistochemistry and transmission electron microscopy. In addition, to study the microvasculature of the subplacenta, vessel casts were inspected by scanning electron microscopy RESULTS: In the subplacenta, lamellae of connective tissue support a layer of mononuclear cytotrophoblast cells. Beneath this is found syncytiotrophoblast. Clusters of multinuclear giant cells occur in the transition zone between the subplacenta and decidua. There are prominent intercellular spaces between the cytotrophoblast cells. The basal membrane of these cells is often close to fetal blood vessels. The syncytiotrophoblast surrounds an extensive system of lacunae. Microvilli project into these lacunae from the plasma membrane of the syncytiotrophoblast. The syncytial cytoplasm contains electron-dense granules. This is probably the amylase-resistant PAS-positive material identified by histochemistry. The subplacenta is supplied entirely from the fetal circulation. Within it the vessels pursue a tortuous course with sinusoidal dilatations and constrictions. CONCLUSION: The functions that have been attributed to the subplacenta include hormone production. Our findings are consistent with this interpretation, but suggest that hormone secretion is directed towards the fetal circulation rather than the maternal tissues

Six1 homeoprotein drives myofiber type IIA specialization in soleus muscle

International audienceAbstractBackgroundAdult skeletal muscles are composed of slow and fast myofiber subtypes which each express selective genes required for their specific contractile and metabolic activity. Six homeoproteins are transcription factors regulating muscle cell fate through activation of myogenic regulatory factors and driving fast-type gene expression during embryogenesis.ResultsWe show here that Six1 protein accumulates more robustly in the nuclei of adult fast-type muscles than in adult slow-type muscles, this specific enrichment takes place during perinatal growth. Deletion of Six1 in soleus impaired fast-type myofiber specialization during perinatal development, resulting in a slow phenotype and a complete lack of Myosin heavy chain 2A (MyHCIIA) expression. Global transcriptomic analysis of wild-type and Six1 mutant myofibers identified the gene networks controlled by Six1 in adult soleus muscle. This analysis showed that Six1 is required for the expression of numerous genes encoding fast-type sarcomeric proteins, glycolytic enzymes and controlling intracellular calcium homeostasis. Parvalbumin, a key player of calcium buffering, in particular, is a direct target of Six1 in the adult myofiber.ConclusionsThis analysis revealed that Six1 controls distinct aspects of adult muscle physiology in vivo, and acts as a main determinant of fast-fiber type acquisition and maintenance

Desenvolvimento de metodologias ativas para o ensino de anatomia humana / Development of active methodologies for the teaching of human anatomy

O tradicionalismo torna o ensino da anatomia mecânico e engessado. A necessidade de abstração e peças anatômicas de estudo são um dos principais fatores dificultantes do processo de ensino e aprendizagem de anatomia humana. A partir daí surgiu a necessidade de se buscar novas metodologias que possam facilitar e atrair os alunos para o estudo da anatomia.  o presente trabalho traz toda a elaboração, aplicação e vivência da aplicação de metodologias ativas de ensino na Anatomia humana no ensino superior. Foram desenvolvidas e aplicadas diversas metodologias ativas de ensino como Aprendizagem Baseada em Jogos, Utilização de Recursos Audiovisuais e Aprendizagem Baseada em Artes Visuais. As propostas foram desenvolvidas por alunos da Universidade Federal Rural de Pernambuco e aplicadas em escolas estaduais da região metropolitana do Recife. As metodologias ativas ajudaram os alunos na absorção e fixação dos conteúdos de anatomia humana.

Desenvolvimento de metodologias ativas para o ensino de anatomia humana / Development of active methodologies for the teaching of human anatomy

O tradicionalismo torna o ensino da anatomia mecânico e engessado. A necessidade de abstração e peças anatômicas de estudo são um dos principais fatores dificultantes do processo de ensino e aprendizagem de anatomia humana. A partir daí surgiu a necessidade de se buscar novas metodologias que possam facilitar e atrair os alunos para o estudo da anatomia.  o presente trabalho traz toda a elaboração, aplicação e vivência da aplicação de metodologias ativas de ensino na Anatomia humana no ensino superior. Foram desenvolvidas e aplicadas diversas metodologias ativas de ensino como Aprendizagem Baseada em Jogos, Utilização de Recursos Audiovisuais e Aprendizagem Baseada em Artes Visuais. As propostas foram desenvolvidas por alunos da Universidade Federal Rural de Pernambuco e aplicadas em escolas estaduais da região metropolitana do Recife. As metodologias ativas ajudaram os alunos na absorção e fixação dos conteúdos de anatomia humana.

Implementing Autism Screening for Latino Children in Primary Care: Perspectives from Parents and Providers

While Autism Spectrum Disorder (ASD) and other developmental disabilities are being diagnosed at increasing rates, there is strong evidence of disparities in rates of identification and utilization of services by Latino children as compared to non-Latino children. Attempts to reduce these disparities include culturally-informed early screening for ASD risk. In preparation for initiation of a screening program in a primary care setting serving primarily Latino children, focus groups and interviews were conducted with Latino parents (N=31), medical staff (N=15), health care providers (N=4) to better understand the barriers and facilitators to engagement around developmental concerns that contribute to the low identification and service use for Latino children with autism. Using a thematic analysis approach, focus group and interview data revealed themes organized around three issues impacting engagement of Latino parents in screening for ASD: 1) information exchange, 2) culture, and 3) structure. In particular, parents and providers, felt that it was important to connect on the importance of developmental issues, address health literacy, acknowledge differences in language, beliefs, and values, and address structural barriers, like length of patient/provider interaction. Information obtained through this qualitative study informed the intervention, Supported Screening, to facilitate screening and referral for ASD at primary care sites that serve predominantly Latino families

Mixed methods research in Latin America : initiatives and opportunities for expansion

Abstract: Please refer to full text to view abstract

Dependency Theory and the Aesthetics of Contrast in Fernando Solanas’s La hora de los hornos and Memoria del saqueo

This paper is a comparative analysis of two key documentaries by Fernando Solanas: La hora de los hornos / The Hour of the Furnaces (1966–68) and Memoria del saqueo / Social Genocide (2003). It argues that Solanas produces documentaries when the representative link that ties the political representatives to the represented (the people) is suspended or breaks down, as experienced during the times of the proscription of Peronism (1955–73) and in the more recent crisis of representation in Argentine institutional politics (1989–2001). The comparison follows two axes: political arguments and the aesthetics of contrast. Regarding the first criterion, the paper highlights the current persistence, in Solanas’s political argumentation, of externalist-mechanistic versions of dependency theory of the late 1960s and early 1970s. In relation to the aesthetics of contrast, it analyses the stark oppositions in Solanas’s documentaries as a visual rhetoric which can be read as an essentialist false-bottom economy that opposes ‘appearance’ to ‘reality’. The article concludes that these political and aesthetic polarizations are essentializing and literalizing discursive strategies that denounce the excesses of political representation from an unmediated and transparent site of full popular presence. Within such strategies, there is no room for the constitutive opacity intrinsic to representation and articulatory politics