Sistemas de PEMFC são capazes de gerar energia elétrica com alta eficiência e baixa ou nenhuma emissão de poluentes, porém questões de custo e durabilidade impedem sua ampla comercialização. Nesse trabalho foi desenvolvido um MEA com eletrocatalisadores à base de paládio. Foram sintetizados e caracterizados eletrocatalisadores Pd/C, Pt/C e Ligas PdPt/C com diferentes razões entre metais e carbono. Foi realizado um estudo da razão entre ionômero de Nafion e eletrocatalisador para formação de triplas fases reacionais de máximos desempenhos, criado um modelo matemático para transpor esse ajuste para eletrocatalisadores com diferentes razões entre metal e suporte, considerando os aspectos volumétricos da camada catalisadora, e então realizado um estudo da espessura da camada catalisadora. Para as caracterizações foram utilizadas as técnicas de Difração de Raios-X, Microscopias Eletrônicas de Transmissão e de Varredura, Energia Dispersiva de Raios-X, Picnometria a Gás, Porosimetria por Intrusão de Mercúrio, Adsorção de Gás, segundo as equações de BET e BJH, Análise Termo Gravimétrica e feitas as determinações de diâmetros de partículas, de áreas de superfície específica e de parâmetros de rede. Todos os eletrocatalisadores foram usados no preparo de MEAs que foram avaliados em célula unitária de 5 cm2 entre 25 e 100 °C a 1 atm; e a melhor composição foi avaliada também a 3 atm. No estudo dos metais para as reações, visando reduzir a platina aplicada aos eletrodos, sem perdas de desempenho, foram selecionados Pd/C para ânodos e PdPt/C 1:1 para cátodos. A estrutura de MEA desenvolvida utilizou 0,25 mgPt.cm-2 e resultou em densidades de potência de até 550 mW.cm-2 e potências de até 2,2 kWe por grama de platina. A estimativa realizada mostrou que houve uma redução de até 64,5 % nos custos em relação à estrutura de MEA previamente conhecida. Em função da temperatura e pressão de operação foram obtidos valores a partir de R$ 3.540,73 para o preparo de MEAs para cada quilowatt instalado. Com base em estudos recentes, concluiu-se que o custo do MEA desenvolvido é compatível às aplicações estacionárias de PEMFC. / PEMFC systems are capable of generating electricity with high efficiency and low or no emissions, but durability and cost issues prevent its large commercialization. In this work MEA with palladium based catalysts were developed, Pd/C, Pt/C and alloys PdPt/C catalysts with different ratios between metals and carbon were synthesized and characterized. A study of the ratio between catalyst and Nafion Ionomer for formation of high performance triple-phase reaction was carried out, a mathematical model to implement this adjustment to catalysts with different relations between metal and support taking into account the volumetric aspects of the catalyst layer was developed and then a study of the catalyst layer thickness was performed. X-ray diffraction, Transmission and Scanning Electron Microscopy, X-ray Energy Dispersive, Gas Pycnometry, Mercury Intrusion Porosimetry, Gas adsorption according to the BET and BJH equations, and Thermo Gravimetric Analysis techniques were used for characterization and particle size, specific surface areas and lattice parameters determinations were also carried out. All catalysts were used on MEAs preparation and evaluated in 5 cm2 single cell from 25 to 100 °C at 1 atm and the best composition was also evaluated at 3 atm. In the study of metals for reactions, to reduce the platinum applied to the electrodes without performance losses, Pd/C and PdPt/C 1:1 were selected for anodes and cathodes, respectively. The developed MEA structure used 0,25 mgPt.cm-2, showing power densities up to 550 mW.cm-2 and power of 2.2 kWnet per gram of platinum. The estimated costs showed that there was a reduction of up to 64.5 %, compared to the MEA structures previously known. Depending on the temperature and operating pressure, values from US$ 1,475.30 to prepare MEAs for each installed kilowatt were obtained. Taking into account recent studies, it was concluded that the cost of the developed MEA is compatible with PEMFC stationary application.

Sistemas de PEMFC são capazes de gerar energia elétrica com alta eficiência e baixa ou nenhuma emissão de poluentes, porém questões de custo e durabilidade impedem sua ampla comercialização. Nesse trabalho foi desenvolvido um MEA com eletrocatalisadores à base de paládio. Foram sintetizados e caracterizados eletrocatalisadores Pd/C, Pt/C e Ligas PdPt/C com diferentes razões entre metais e carbono. Foi realizado um estudo da razão entre ionômero de Nafion e eletrocatalisador para formação de triplas fases reacionais de máximos desempenhos, criado um modelo matemático para transpor esse ajuste para eletrocatalisadores com diferentes razões entre metal e suporte, considerando os aspectos volumétricos da camada catalisadora, e então realizado um estudo da espessura da camada catalisadora. Para as caracterizações foram utilizadas as técnicas de Difração de Raios-X, Microscopias Eletrônicas de Transmissão e de Varredura, Energia Dispersiva de Raios-X, Picnometria a Gás, Porosimetria por Intrusão de Mercúrio, Adsorção de Gás, segundo as equações de BET e BJH, Análise Termo Gravimétrica e feitas as determinações de diâmetros de partículas, de áreas de superfície específica e de parâmetros de rede. Todos os eletrocatalisadores foram usados no preparo de MEAs que foram avaliados em célula unitária de 5 cm2 entre 25 e 100 °C a 1 atm; e a melhor composição foi avaliada também a 3 atm. No estudo dos metais para as reações, visando reduzir a platina aplicada aos eletrodos, sem perdas de desempenho, foram selecionados Pd/C para ânodos e PdPt/C 1:1 para cátodos. A estrutura de MEA desenvolvida utilizou 0,25 mgPt.cm-2 e resultou em densidades de potência de até 550 mW.cm-2 e potências de até 2,2 kWe por grama de platina. A estimativa realizada mostrou que houve uma redução de até 64,5 % nos custos em relação à estrutura de MEA previamente conhecida. Em função da temperatura e pressão de operação foram obtidos valores a partir de R$ 3.540,73 para o preparo de MEAs para cada quilowatt instalado. Com base em estudos recentes, concluiu-se que o custo do MEA desenvolvido é compatível às aplicações estacionárias de PEMFC. / PEMFC systems are capable of generating electricity with high efficiency and low or no emissions, but durability and cost issues prevent its large commercialization. In this work MEA with palladium based catalysts were developed, Pd/C, Pt/C and alloys PdPt/C catalysts with different ratios between metals and carbon were synthesized and characterized. A study of the ratio between catalyst and Nafion Ionomer for formation of high performance triple-phase reaction was carried out, a mathematical model to implement this adjustment to catalysts with different relations between metal and support taking into account the volumetric aspects of the catalyst layer was developed and then a study of the catalyst layer thickness was performed. X-ray diffraction, Transmission and Scanning Electron Microscopy, X-ray Energy Dispersive, Gas Pycnometry, Mercury Intrusion Porosimetry, Gas adsorption according to the BET and BJH equations, and Thermo Gravimetric Analysis techniques were used for characterization and particle size, specific surface areas and lattice parameters determinations were also carried out. All catalysts were used on MEAs preparation and evaluated in 5 cm2 single cell from 25 to 100 °C at 1 atm and the best composition was also evaluated at 3 atm. In the study of metals for reactions, to reduce the platinum applied to the electrodes without performance losses, Pd/C and PdPt/C 1:1 were selected for anodes and cathodes, respectively. The developed MEA structure used 0,25 mgPt.cm-2, showing power densities up to 550 mW.cm-2 and power of 2.2 kWnet per gram of platinum. The estimated costs showed that there was a reduction of up to 64.5 %, compared to the MEA structures previously known. Depending on the temperature and operating pressure, values from US$ 1,475.30 to prepare MEAs for each installed kilowatt were obtained. Taking into account recent studies, it was concluded that the cost of the developed MEA is compatible with PEMFC stationary application.

The subject of this thesis is the usage of economic instruments (EIs) in multilateral environmental agreements (MEAs) and their relation to international economic law. The thesis aims at analysing and evaluating the possibilities of using economic instruments, their potential to ensure the compliance with the treaties' provisions and assessing, under which conditions it is possible to use them in compliance with the international economic law. As a lot of economic instruments operate with restrictions to international trade in several manners, they can get in conflict with the law embodying this area, namely the law of the World Trade Organization. The thesis therefore analyses the main principles and provisions of General Agreement on Tariffs and Trade that can affect the usage of EIs in MEAs. Most attention is paid to the interpretation of exemptions from the Agreement that can legalize such restrictions. Trade-Related Environmental Measures shouldn't be discriminatory. They shouldn't present arbitrary or unjustifiable restriction to trade against the principles and provisions of the WTO agreements. Such restrictions can only be made based on international agreement. The case of trade restriction based on MEA wasn't yet considered by Dispute Settlement Body and the answer hence depends on the...

Made available in DSpace on 2016-04-28T14:59:46Z (GMT). No. of bitstreams: 1 2007 - Erika Cristina Dias de Oliveira.pdf: 213966 bytes, checksum: dbf8cfca7211b798b6da84c3d31f3aa5 (MD5) Previous issue date: 2007-11-13 / Meat characteristics of ? Guzer? x ? Simmental x ? Nellore (GG1); ? Guzer? x ? Limousin x ? Nellore (GG2) and ? Guzer? x ? Simbrasil x ? Nellore (GG3) heifers were evaluated. Each experimental group was constituted by eight animals. The females were finished in feedlot and presented respective average weights to GG1; GG2 and GG3 of 379,33 ? 13.65; 378.00 ? 11.53 kg and 382.83 ? 9.25 kg at the feedlot beginning and 446.00 ? 10.07 kg; 441.00 ? 10.54 kg e 449.00 ? 11.53 kg in the slaughter occasion. The heifers consumed a diet with 12.5% of crude protein and 73.5% of total digestible nutrients (TDN). The roughage was constituted by millet grass and the concentrate by sorghum. cottonseed. limestone and sugar cane residue. There was no significant difference (P>0.05) to the percentages of damp (74.12; 75.12% and 75.65%). ether extract (1.98; 2.30% e 2.22%). crude protein (23.19; 22.15% and 22.29%)). defrosting loss (6.54; 5.89% and 6.03%). as well as to the averages obtained to coloration (4.38; 4.50 and 4.38). texture (4.63; 4.50 e 4.38). firmness (4.38 and 4.63). taste (8.38 and 8.63). juiciness (8.63; 8.50 and 8.38) and tenderness (8.25 and 7.75) evaluated by panel method. . The meat from GG2 and GG3 animals. presented major losses on coction (25.92% and 27.46% vs 21.95%) and superior mineral contents (4.31% e 4.40% vs 3.87%) in relation to GG1. Considering the experimental conditions and the evaluated genetic groups. it was concluded that ? Guzer? x ? Limousin x ? Nellore. and ? Guzer? x ? Simbrasil x ? Nellore heifers present similar meat quality observed by the homogeneity existent between the groups to the evaluated characteristics. The taurine genotype until 25% does not promote differences in meat sensorial items and losses by defrosting. except to minor losses on coction and mineral contents influence by the Simmental genotype. / As caracter?sticas da carne de novilhas ? Guzer? x ? Simental x ? Nelore (GG1) ; ? Guzer? x ? Limousin x ? Nelore (GG2) e ? Guzer? x ? Simbrasil x ? Nelore (GG3) foram avaliadas. Cada grupo experimental era constitu?do por oito animais. As f?meas foram terminadas em confinamento e apresentaram pesos m?dios respectivos para GG1; GG2 e GG3 de 379,33 ? 13,65; 378,00 ? 11,53 kg e 382,83 ? 9,25 kg no in?cio do confinamento e 446,00 ? 10,07 kg ; 441,00 ? 10,54 kg e 449,00 ? 11,53 kg na ocasi?o do abate. As novilhas consumiram uma dieta com 12,5% de prote?na bruta e 73,5% de nutrientes digest?veis totais (NDT). O volumoso foi constitu?do por silagem de milheto e o concentrado a base de sorgo, caro?o de algod?o, calc?rio calc?tico e mela?o. N?o houve diferen?a significativa (P>0,05) para as percentagens de umidade (74,12; 75,12% e 75,65%), extrato et?reo (1,8; 2,30% e 2,22%), prote?na bruta (23,19; 22,15% e 22,29%) e perda no descongelamento (6,54; 5.89% e 6,03%), bem como para as m?dias obtidas para colora??o (4.38; 4,50 e 4,38), textura (4,63; 4,50 e 4,38), firmeza (4,38 e 4,63), sabor (8,38 e 8,63), sucul?ncia (8,63; 8,50 e 8,38) e maciez (8,25 e 7,75) avaliadas pelo m?todo do painel. As carnes das novilhas GG2 e GG3 apresentaram maiores perdas na coc??o (25,92% e 27,46% vs 21,95%) e teores mais elevados de mat?ria mineral (4,31% e 4,40% vs 3,87%) em rela??o ao GG1. Considerando as condi??es experimentais e os grupos gen?ticos avaliados, conclui-se que novilhas ? Guzer? x ? Limousin x ? Nelore, e ? Guzer? x ? Simbrasil x ? Nelore apresentam carne de qualidade semelhante observada pela homogeneidade existente entre os grupos para as caracter?sticas estudadas. O grau de sangue taurino em at? 25% n?o promove diferen?a na carne para os itens sensoriais e perdas por descongelamento, com exce??o da menor perda por coc??o e teor de minerais influenciado pelo sangue Simental.

Made available in DSpace on 2014-12-17T15:37:03Z (GMT). No. of bitstreams: 1 CristinaE_DISSERT.pdf: 524500 bytes, checksum: 7087fd25119bfbf656e04c3c7d840371 (MD5) Previous issue date: 2010-10-08 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Considering the constant environmental changes, the ability to introduce new food items in the diet is crucial to omnivore animal survival. For optimal nourishment and lessening of intoxication risks, the animals must detect signs that indicate which items are adequate for their intake. We investigate some factors that interfere in the responses to non familiar food, modulating their neophobic behavior, of marmosets Callithrix jacchus, an omnivore and generalist primate, native to Northeast Brazil, known for being cautious in ingesting not known food. We analyzed the influence of food taste (sweet or salty), pregnancy and sex in feeding behavior and neophobic responses in these animals. 10 captive females were first selected, 5 of them being then pregnant. The females, pregnant or not, ate more when presented to the sweet items than to the salty ones. Pregnant females, however, themselves were less neophobic to both tastes, being also strongly neophilic to the sweets. We verified then the influence of nourishment during pregnancy on young males and females post natal feeding behavior. We observed 10 young divided in two groups, one whose mother ate that food item during pregnancy and one whose mother had no contact to it. In the first group that food was more easily accepted by the young, suggesting that neofobia and feeding behavior had a pre natal influence. Female young also ingested more food and were less neophobic than males, a difference already observed in behavior of adults of these specie. These results suggest that the low neophobic behavior to sweet food showed by females can be adaptive, and might have bestowed more fitness to those who presented it / Considerando as constantes mudan?as ambientais, a capacidade de introduzir alimentos novos na dieta ? essencial para a sobreviv?ncia de animais on?voros. Para a otimiza??o do forrageio e diminui??o dos riscos de intoxica??o, ? necess?rio ao animal detectar sinais que indiquem quais itens s?o adequados ou n?o para o consumo. Investigamos alguns fatores que interferem na resposta aos alimentos n?o familiares, modulando comportamentos neof?bicos em sag?is Callithrix jacchus, primatas nativos do nordeste brasileiro, animais on?voros e generalistas, por?m cautelosos na ingest?o de itens desconhecidos. Foi analisada a influ?ncia da qualidade gustativa dos alimentos (doce e salgado), da gesta??o, e do sexo no comportamento alimentar e na resposta neof?bica desses animais. Selecionamos inicialmente 10 f?meas de origem cativa, sendo cinco gr?vidas e cinco n?o. As f?meas apresentadas aos itens doces ingeriram maior quantidade do que aquelas apresentadas ao item salgado, estando ou n?o gestantes. Contudo, f?meas gr?vidas se mostraram menos neof?bicas para ambos os alimentos, embora demonstrassem forte neofilia para os doces. Verificamos ent?o a influ?ncia da alimenta??o das gr?vidas no comportamento alimentar p?s-natal de seus filhotes f?meas e machos. Observamos 10 filhotes: um grupo cuja m?e teve contato com o alimento na gesta??o e um cuja m?e n?o tivera esse contato. No primeiro grupo o alimento foi mais facilmente aceito pelos filhotes, sugerindo que a neofobia e a prefer?ncia alimentar possuam influ?ncia pr?-natal. Al?m disso, filhotes f?meas ingeriram mais alimentos e mostraram-se menos neof?bicas que filhotes machos, diferen?a j? observada em adultos da mesma esp?cie. Nossos resultados sugerem que o comportamento de baixa neofobia aos alimentos doces apresentado pelas f?meas possa ser adaptativo, e tenha conferido uma maior aptid?o ?quelas que o apresentassem

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-13T20:11:13Z No. of bitstreams: 1 BarbaraThaiseDaSilvaFreire_DISSERT.pdf: 2117227 bytes, checksum: ea3ed2322a685c0dbab26e3132b6aeee (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-15T23:55:52Z (GMT) No. of bitstreams: 1 BarbaraThaiseDaSilvaFreire_DISSERT.pdf: 2117227 bytes, checksum: ea3ed2322a685c0dbab26e3132b6aeee (MD5) / Made available in DSpace on 2017-02-15T23:55:52Z (GMT). No. of bitstreams: 1 BarbaraThaiseDaSilvaFreire_DISSERT.pdf: 2117227 bytes, checksum: ea3ed2322a685c0dbab26e3132b6aeee (MD5) Previous issue date: 2016-07-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O envolvimento de receptores do tipo 5-HT3, assim como a rela??o do N?cleo Dorsal da Rafe na modula??o da ansiedade vem sendo citados na literatura. Levando em considera??o a grande parcela da popula??o que ? afetada pelos transtornos de ansiedade, torna-se imprescind?vel a procura por novas formas de tratamento mais eficientes e pelo aumento do conhecimento acerca do assunto. Nesse sentido, o objetivo do presente estudo ? testar a hip?tese de que receptores do tipo 5-HT3 presentes na por??o dorsal do n?cleo dorsal da rafe (NDR) modulem as respostas relacionadas ? ansiedade em ratas. No experimento 1, ratas Wistar com ? 90 dias de idade receberam tratamento (v.o) de ondansetrona na dose de 0,1, 1 e 10 mg/kg/mL e, 60 minutos ap?s, foram submetidas ao teste do Labirinto em T Elevado (LTE). 24 horas ap?s o LTE, os animais receberam novamente a ondansetrona e foram submetidas ao teste do Campo Aberto. Nos experimentos 2 e 3, as ratas foram submetidas ? cirurgia estereot?xica para implanta??o de c?nula intra-NDR e receberam administra??o local de salina ou dolasetrona nas doses de 100, 500 e 1000nmol (experimento 2) ou salina ou mCPBG nas doses de 2,5, 5 e 10?g (experimento 3). Em ambos, 5 minutos ap?s a infus?o com a droga, os animais foram submetidos ao teste do LTE, e 24 horas ap?s, receberam infus?o e foram submetidos ao teste do Campo Aberto para obten??o de curvas doseresposta. A ondansetrona na dose de 10mg/Kg/mL aumentou a lat?ncia de fuga no LTE, sugerindo um efeito do tipo panicol?tico. A dolasetrona n?o promoveu nenhum efeito no teste do LTE, em nenhuma das doses testadas. J? o agonista mCPBG em todas as doses aumentou a lat?ncia de esquiva inibit?ria em todas as tentativas, sugerindo um efeito do tipo ansiog?nico. Os resultados obtidos no teste do Campo Aberto mostrou que n?o houve altera??o na atividade locomotora das ratas causada pelos tratamentos. Os dados obtidos refor?am a import?ncia dos receptores 5-HT3 no NDR na modula??o da ansiedade. / The involvement of both 5-HT3 receptors and dorsal raphe nucleus in the modulation of anxiety has been presented in the literature. Considering that most of population is affected by anxiety disorders, it is essential to search for new and more efficient forms of treatment and to increase the knowledge on the subject. The aim of this study is to test the hypothesis that the 5-HT3 receptors in the dorsal part of the dorsal raphe nucleus (dNDR) modulates the responses related to anxiety in rats. In experiment one, female Wistar rats with ? 90 days old were treated (p.o.) with ondansetron at doses of 0.1, 1 and 10 mg/kg/mL and 60 minutes later, were submitted to the elevated T maze (ETM) test. 24 hours later, they received ondansetron and were submitted to the open Field Test. In the experiments 2 and 3, the rats were submitted to the stereotactic surgery for implantation of intra-NDR cannula and received administration (via infusion) of saline or dolasetron at doses of 100, 500 and 1000nmol (experiment 2) or saline or mCPBG at doses of 2.5, 5 and 10mg (experiment 3). In both experiments, 5 minutes after the infusion of the drug, the animals were submitted to the test of ETM, and 24 hours after, they received drug infusion and were submitted to the open field test, to obtain dose-response curves. Ondansetron at a dose of 10mg/kg/mL increased latency of escape response in ETM, suggesting an panicolytic-like effect. The dolasetron caused no effect in ETM test in any of the tested doses. The agonist mCPBG instead, increased the inhibitory avoidance latency in all doses, suggesting an anxiogenic-like effect. Data obtained in the open field test showed no change in locomotor activity of rats following the treatments. The data here obtained supports the importance of 5-HT3 receptors in the NDR in the modulation of anxiety.

>Magister Scientiae - MSc / Polymer electrolyte membrane fuel cells (PEMFCs) among other fuel cells are considered the best candidate for commercialization of portable and transportation applications because of their high energy conversion and low pollutant emission. Recently, there has been significant interest in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), due to certain advantages such as simplified system and better tolerance to CO poisoning. Cost, durability and the reliability are delaying the commercialization of PEM fuel cell technology. Above all durability is the most critical issue and it influences the other two issues. The main objective of this work is to study the durability of membrane electrode assemblies (MEAs) for HT-PEMFC. In this study the investigation of commercial MEAs was done by evaluating their performance through polarization studies on a single cell, including using pure hydrogen and hydrogen containing various concentrations of CO as fuel, and to study the performance of the MEAs at various operating temperatures. The durability of the MEAs was evaluated by carrying out long term studies with a fixed load, temperature cycling and open circuit voltage degradation. Among the parameters studied, significant loss in the performance of the MEAs was noted during temperature cycling. The effect of temperature cycling on the performance of the cell showed that the performance decreases with increasing no. of cycles. This could be due to leaching of acid from the cell or loss of electrochemically active surface area caused by Pt particle size growth. For example at 160°C, a performance loss of 3.5% was obtained after the first cycle, but after the fourth cycle a huge loss of 80.8% was obtained. The in-house MEAs with Pt-based binary catalysts as anodes were studied for CO tolerance, performance and durability. A comparison of polarization curves between commercial and in-house MEAs illustrated that commercial MEA gave better performance, obtaining 0.52 A/cm² at 0.5V and temperature of 160°C, with in-house giving 0.39A/cm² using same parameters as commercial. The CO tolerance of both commercial and in-house MEA was found to be similar. In order to increase the CO tolerance of the in-house MEAs, Pt based binary catalysts were employed as anodesand the performance was investigated In-house MEAs with Pt/C and Pt-based binary catalysts were compared and a better performance was observed for Pt/C than Pt-alloy catalysts with Pt-Co/C showing comparable performance. At 0.5 V the performance obtained was 0.39 A/cm2 for Pt/C, and 0.34A/cm²,0.28A/cm²,0.27A/cm² and 0.16A/cm² were obtained for Pt-Co/C, Pt-Fe/C, Pt-Cu/C and Pt-Ni respectively. When the binary catalysts were tested for CO tolerance, Pt-Co showed no significant loss in performance when hydrogen containing CO was used as anode fuel. Scanning electron microscopy (SEM) revealed delamination between the electrodes and membrane of the tested and untested MEA's. Membrane thinning was noted and carbon corrosion was observed from the tested micro-porous layer between the gas diffusion layer (GDL) and catalyst layer (CL).

Micro-direct methanol fuel cells (micro-DMFC) can be the power supply solution for the next generation of handheld devices. The applications of the micro-DMFCs require them to have high compactness, high performance, light weight, and long life. The major goal of this research project is to enhance the volumetric power density of direct methanol fuel cells (DMFCs). A performance roadmap has been formulated and showed that patterning the planar membrane electrode assembly (MEA) to 2-D and 3-D corrugated manifolds can greatly increase the power generation with very modest overall volume increases. In this project, different manufacturing processes for patterning MEAs with corrugations have been investigated. A folding process was selected to form 2D triangular corrugations on MEAs for experimental validations of the performance prediction. The experimental results show that the volumetric power densities of the corrugated MEAs have improved by about 25% compared to the planar MEAs, which is lower than the expected performance enhancement. ABAQUS software was used to simulate the manufacturing process and identify the causes of deformations during manufacture. Experimental analysis methods like impedance analysis and 4 point-probes were used to quantify the performance loss and microstructure alteration during the forming process. A model was proposed to relate the expected performance of corrugated MEAs to manufacturing process variables. Finally, different stacking configurations and issues related to cell stacking for corrugated MEAs are also investigated.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-11-22T21:32:18Z No. of bitstreams: 1 CarolinaMariaCardosoAiresLisboa_TESE.pdf: 1706951 bytes, checksum: 90ca20bb2b95d79b8d221d1fdf02ddc8 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-11-24T22:51:37Z (GMT) No. of bitstreams: 1 CarolinaMariaCardosoAiresLisboa_TESE.pdf: 1706951 bytes, checksum: 90ca20bb2b95d79b8d221d1fdf02ddc8 (MD5) / Made available in DSpace on 2017-11-24T22:51:37Z (GMT). No. of bitstreams: 1 CarolinaMariaCardosoAiresLisboa_TESE.pdf: 1706951 bytes, checksum: 90ca20bb2b95d79b8d221d1fdf02ddc8 (MD5) Previous issue date: 2017-06-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A sele??o sexual ? respons?vel pela evolu??o de diversos sinais visuais consp?cuos utilizados na comunica??o intra e interespec?fica de in?meras esp?cies. Os lagartos t?m sistema visual com fotorreceptores que s?o sens?veis aos comprimentos de onda UV, e algumas esp?cies utilizam ornamentos de cor UV na comunica??o. Neste estudo, utilizamos espectrofotometria para obter evid?ncias de ornamenta??o UV em lagartos Ameivula ocellifera. Utilizando um aparato experimental em formato de arena, obtivemos evid?ncias do papel da sinaliza??o UV na sele??o sexual (prefer?ncia de f?meas e competi??o entre machos). Nossos resultados revelaram que a sinaliza??o UV ? importante na prefer?ncia de f?meas, uma vez que as mesmas exibem prefer?ncia por machos com maior reflect?ncia UV em rela??o aos machos com reflect?ncia experimentalmente reduzida. Tamb?m descobrimos que os machos com UV reduzido n?o foram mais propensos a perder disputas do que os controle, embora quanto maior a diferen?a de reflect?ncia UV entre os pares, menor o tempo de avalia??o entre os rivais antes do combate. Para avaliar se os sinais de cor s?o informativos da qualidade, testamos dois ornamentos de machos de A. ocellifera contra tra?os morfol?gicos e desempenho fisiol?gico. Descobrimos que machos maiores apresentaram comprimentos de onda UV e m?dio mais intensos nos ocelos dorsolaterais e, em contraste, os machos de cabe?a menor tiveram o croma UV mais intenso nas escamas ventrais exteriores (EVEs). Conclu?mos que a mesma caracter?stica de cor transmite diferentes mensagens dependendo da posi??o do sinal no corpo dos lagartos, sendo um indicativo de estrat?gias alternativas de sinaliza??o. Al?m disso, um maior brilho nas EVEs foi associado a maior for?a de mordida, sendo este um sinal confi?vel de capacidade de luta do macho. Esses resultados sugerem que existe um sistema de sinaliza??o m?ltipla na esp?cie. Por fim, modelamos os sistemas visuais de A. ocellifera e de dois tipos de predadores (ave de rapina e serpente) para descobrir como as manchas de colora??o s?o percebidas e explorar as consequ?ncias da colora??o consp?cua em termos de press?es seletivas. Encontramos dicromatismo entre os sexos, com a reflect?ncia UV de machos mais vis?veis e altamente distingu?veis dos das f?meas a partir do sistema visual de A. ocellifera. Os sinais UV foram altamente percept?veis quando em contraste com a colora??o do corpo e do ambiente natural para A. ocellifera e, menos mas ainda percept?veis, para os predadores, concordando com a hip?tese da condu??o sensorial. Esta tese esclarece o papel dos sinais sexuais e sua import?ncia nas comunica??es intra e interespec?ficas em lagartos. Nossas descobertas baseiam futuros estudos sobre evolu??o e comportamento e expandem o conhecimento acerca das sele??es natural e sexual propostas por Darwin. / Sexual selection is responsible for the evolution of many conspicuous visual signals used in intra and interspecific communication of innumerous species. Lizards have acute visual systems with retinal photoreceptors that are sensitive to UV wavelengths, and some species use UV colour ornaments for communication. In this study, we used UV full-spectrum reflectance spectrophotometry to collect data from Ameivula ocellifera UV structural colouration. Using an arena-form experimental set, we obtained evidence for the role of UV signaling in sexual selection (mate choice and male-male interactions). Our results showed that UV chroma is important in female association preference, as females exhibit spatial preference for males of higher UV reflectance over males with experimentally reduced UV reflectance. We also found that A. ocellifera males with experimentally reduced UV reflectance were not more likely to lose contests than control males, although bigger the difference of UV reflectance between pairs, smaller the evaluation time between rivals before the contest. We also tested two male ornaments in A. ocellifera against morphological traits and physiological performance to assess whether colour signals are informative for male quality traits. We found that larger males had more intense short (UV) and medium wavelength chroma on dorsolateral eyespots and, in contrast, smaller-headed males had more intense UV chroma on outer ventral scales (OVS). We concluded that the same colour trait convey different messages depending on the body position of the signal, perhaps indicative of alternative signalling strategies. Moreover, higher brightness on OVS signals were associated with stronger bite force, being a reliable signal of fighting ability. These results suggest that there is a multiple signalling system in our model species. Finally, we modeled the visual system of A. ocellifera, snake and avian predators to access how colour patches appear to the receivers. We found that there are dichromatism between sexes, with UV signals of males more conspicuous in reflectance and highly distinguishable from females to conspecifics visual system. UV signals were highly perceptible from body colouration and from natural background to conspecifics and less but still perceptible to predators, agreeing with sensory drive hypothesis. This thesis enlighten the role of sexual signals and their importance on intra and interspecific communications in lizards. Our findings support further studies on evolution and behavior and expand the knowledge on natural and sexual selections initiated by Darwin.

Made available in DSpace on 2014-12-17T15:15:03Z (GMT). No. of bitstreams: 1 FrancysAS-DISSERT.pdf: 2417755 bytes, checksum: 4896a53f5371b0d52af42510d67e075e (MD5) Previous issue date: 2013-11-20 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The study of solar-type stars also includes the familiar solar analogs and twins. These objects have been one of the major research subjects in astrophysics nowadays. A direct comparison of solar activity with chromospheric activity indices for a set of stars very similar to the Sun (twins and analogs) provides an excellent opportunity to study the evolution of stellar activity on timescales of the order of the lifetime on the main sequence. This work deals with the relationship between the abundance of lithium, chromospheric activity, X-ray emission and rotation period in terms of stellar ages. We explore the influence of stellar evolution in the global properties of the stars and the aspects linked to its coronal, chromospheric and magnetic activity. Our main objective is to probe the law of decay of each of these parameters based on a sample of stars classified as well-connected as analogs stars and solar twins. / O estudo das estrelas do tipo solar inclui tamb?m as conhecidas estrelas an?logas e g?meas. Estes objetos tem sido um dos principais objetos de pesquisa da astrof?sica atual. A compara??o direta da atividade solar com os ?ndices de atividade cromosf?rica para um conjunto de estrelas muito semelhantes ao Sol (g?meas e an?logas) fornece uma ?tima oportunidade de estudar a evolu??o da atividade estelar em escalas de tempo da ordem do tempo de vida de uma estrela na sequ?ncia principal. Neste trabalho trataremos das rela??es existentes entre a abund?ncia de l?tio, atividade cromosf?rica, emiss?o de raio-X e per?odo de rota??o em termos das idades estelares. Sondaremos a influ?ncia da evolu??o estelar nas propriedades globais das estrelas e nos aspectos ligados a sua atividade coronal, cromosf?rica e magn?tica. Nosso objetivo principal ? de sondar a lei de decaimento de cada um destes par?metros com base em uma amostra de estrelas bem relacionadas e classificadas como estrelas an?logas e g?meas solares