Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-06-20T16:10:30Z No. of bitstreams: 1 2010 - Cristiane Alves Foga?a.pdf: 2979226 bytes, checksum: 16723accb45fe9477013bff730b4755d (MD5) / Made available in DSpace on 2017-06-20T16:10:30Z (GMT). No. of bitstreams: 1 2010 - Cristiane Alves Foga?a.pdf: 2979226 bytes, checksum: 16723accb45fe9477013bff730b4755d (MD5) Previous issue date: 2010-03-04 / Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ, FAPERJ, Brasil. / The present study aimed to evaluate some limiting factors to the growth of Toona ciliata M. Roem. var. australis (Australian red cedar). In chapter I, it was evaluated the growth of Toona ciliata seedlings inoculated with arbuscular mycorrhizae fungi (FMAs), Acaulospora laevis, A. morrowiae, Entrophospora colombiana, E. contigua, Gigaspora margarita, Glomus clarum, Scutellospora calospora, S. gilmorei, S. heterogama e S. pellucida. In chapter II, it was evaluated the contents and accumulations of nutrients in Australian red cedar seedlings, submitted the complete solution, diluted solution 1/2 and 1/4. In chapter III, it was verified the symptoms of macronutrients deficiency, nutrients contents and accumulations in the Australian red cedar plants submitted the complete solution with omission of N, P, K, Ca and Mg. Chapter IV, it was observed the reply of the species the aluminum presence, using treatments with complete solution diluted the 1/4 with addition of 0, 5 and 20 mg. L-1 de Al. Between AMF tested, A. morrowiae, E. contigua e S. pellucida were most efficient in promoting the accumulation of dry weight of aerial part, development of the area leaf and phosphorous content on leaf in Toona ciliata seedlings, beyond presenting the biggest densities of esporos.50 cm-3 of substrate. And the biggest incidence of mycorrhizae settling in Toona ciliata seedlings was gotten with the species S. pellucida. The behavior of the species in reply to the use of nutritional solutions complete and diluted 1/2 and 1/4, showed that the biggest increment in height, diameter and dry weight had occurred in plants submitted at diluted solution the 1/4. The macronutrients contents and accumulations in Australian red cedar plants presented the following decreasing order: N > K > Ca > P > Mg. With regard to nutritional deficiency it verified that the omission of K was the one that more affected the development of the plant in height. The limitation in the increment stem diameter of the plants occurred in all the treatments, with exception of the complete solution. The production of total weight dry of the plants was affected in all the treatments with omission of nutrients, in according the following decreasing order: Complete Solution > - P > - Mg > - N > - K > - Ca. The initial growth of Toona ciliata seedlings was affected by the omission of all the macronutrients, having been the similar symptoms with the symptoms of other species of the same family. The immediate damages most intense and had been observed in the omission of K and Ca. Thus, the Toona ciliata species demonstrated to be demanding in macronutrients in the following decreasing order: K > N > Mg > Ca > P. The reply of the species the aluminum presence demonstrated that the growth, nutrient content and accumulation in Australian red cedar plants were stimulated in the presence of 5mg.L-1 of aluminum. The addition of 20 mg.L-1 de Al reduced the growth of the plants and macronutrients accumulation, in the following decreasing order: Ca > Mg > N > P > K. The visual symptoms of fitotoxicity had been typical to this element, beyound of the leaf with intense green coloration progressing for the yellow; the leaves oldest had progressed for yellow-brown, the edges to the limb center; and curving of new leaves. / O presente trabalho teve como objetivo avaliar alguns fatores limitantes ao crescimento de Toona ciliata M. Roem. var. australis (cedro-australiano). No cap?tulo I, avaliou-se o crescimento de mudas de cedro-australiano inoculadas com fungos micorr?zicos arbusculares (FMAs), Acaulospora laevis, A. morrowiae, Entrophospora colombiana, E. contigua, Gigaspora margarita, Glomus clarum, Scutellospora calospora, S. gilmorei, S. heterogama e S. pellucida. No cap?tulo II, foram avaliados os teores e ac?mulos de nutrientes em mudas de cedro-australiano, submetidas ? solu??o nutritiva de Hoagland & Arnon modificada, completa, dilu?da a 1/2 e a 1/4 de for?a i?nica. No cap?tulo III, verificou-se os sintomas de defici?ncia de macronutrientes, teores e ac?mulos de nutrientes nas plantas de cedroaustraliano crescidas em solu??o nutritiva com omiss?o de N, P, K, Ca e Mg. No Cap?tulo IV, observou-se a resposta da esp?cie estudada na presen?a de alum?nio, empregando tratamentos com solu??o nutritiva dilu?da a 1/4 com adi??o de 5 e 20 mg.L-1 de Al, al?m de uma testemunha Entre os fungos micorr?zicos arbusculares testados, A. morrowiae, E. contigua e S. pellucida foram os mais eficientes em promover o ac?mulo de mat?ria seca da parte a?rea, desenvolvimento da ?rea foliar e teor de f?sforo foliar em mudas de Toona ciliata, al?m de apresentarem as maiores densidades de esporos por 50 cm3 de substrato. A maior coloniza??o micorr?zica em mudas de Toona ciliata foi obtida com a esp?cie f?ngica S. pellucida. O comportamento da esp?cie em resposta ao emprego de solu??es nutritivas completas, dilu?da a 1/2 e 1/4, mostrou que o maior incremento em altura, di?metro e mat?ria seca ocorreram em plantas submetidas ? solu??o dilu?da a 1/4. Os teores e ac?mulos de macronutrientes em plantas de cedro-australiano seguiram a seguinte ordem decrescente: N > K > Ca > P > Mg. Com rela??o ? defici?ncia nutricional, verificou-se que a omiss?o de K foi a que mais afetou o crescimento em altura. A limita??o no crescimento em di?metro do coleto das plantas ocorreu em todos os tratamentos, com exce??o da solu??o de Hoagland & Arnon. A produ??o de massa seca total das plantas foi afetada em todos os tratamentos com omiss?o de nutrientes, obedecendo ? seguinte ordem decrescente: Completo> -P > -Mg > -N > -K > -Ca. O crescimento inicial de mudas de Toona ciliata ? afetado pela omiss?o de todos os macronutrientes, sendo os sintomas semelhantes com os sintomas de outras esp?cies da mesma fam?lia. Os danos mais intensos e imediatos foram observados na omiss?o de K e Ca. Assim, a esp?cie Toona ciliata demonstrou ser exigente em macronutrientes na seguinte ordem decrescente: K > N > Mg > Ca > P. A resposta da esp?cie ? presen?a de alum?nio demonstrou que o crescimento, teor e ac?mulo de nutrientes em plantas de cedro-australiano foram estimulados na presen?a de 5mg.L-1 de alum?nio. A adi??o de 20 mg.L-1 de Al reduziu o crescimento das plantas e o ac?mulo de macronutrientes, na seguinte ordem decrescente: Ca > Mg > N > P > K. Os sintomas visuais de fitotoxidez associados ? dose de 20 mg.L-1 de Al foram t?picos da toxidez a este elemento, al?m das folhas apresentarem colora??o verde intensa progredindo para o amarelecimento; com a acentua??o dos sintomas, as folhas mais velhas progrediram para amarelo-castanho, dos bordos para o centro do limbo e enrolamento ou encurvamento de folhas novas.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-26T19:35:59Z No. of bitstreams: 1 2016 - David Castor Maxwel de Oliveira.pdf: 6489134 bytes, checksum: 23e02124d5d66aa42a02e4375f4e0862 (MD5) / Made available in DSpace on 2017-06-26T19:35:59Z (GMT). No. of bitstreams: 1 2016 - David Castor Maxwel de Oliveira.pdf: 6489134 bytes, checksum: 23e02124d5d66aa42a02e4375f4e0862 (MD5) Previous issue date: 2016-10-24 / Agroforestry systems (ASF) are potentially characterized as a agroecological crops by the similarity to the forest structure and function which gives more sustainability to the production systems, making them environmentally friendly. This study evaluated an AFS ten years plantation to obtain information about the nitrogen fixing legumes influenced over the soil chemical properties, the palm heart production, the Khaya ivorensis A. Chevalier and Euterpe oleracea Mart. Growth, and finally the common beans cultivation. The AFS was located at Embrapa Agrobiologia Experimental field, at Serop?dica city, Rio de Janeiro state. The statistical was randomized blocks with 5 treatments and 4 replications with 9 m x 9 m plots and total area with 1.620 m2. There were E. oleraceae, planted in a 3 m x 3 m spacing with one plant of K. ivorensis at the plot center. The treatments were different kinds of green manure crops between the lines such as: Acacia angustissima (Mill.) Kuntze; Gliricidia sepium (Jacq.) Steud;. Canavalia ensiformis (L.) DC, nitrogen fertilization with castor cake and spontaneous vegetation. For the soil fertility analyses were collected two samples, one before and other after green manure crops management. K. ivorensis and E. oleraceae biometry, also heart palm production were harmed by inappropriate management on cultivation care lack between post planting and this evaluation lapse. These commercial crops reached larger diameters and superior height at the plot without leguminous crops competition. Green manure crops were efficient in soils nutrients cycling, increasing the most elements content after pruning the leguminous plants and the application of the biomass over the ground. Extract nodules inoculation showed capacity to increase nodulation and nitrogen content in common beans plants, but didn?t increase the grain production. / Os sistemas agroflorestais (SAF) podem ser configurados como cultivos agroecol?gicos, onde a similaridade com as florestas em estrutura e fun??o confere ao sistema uma maior sustentabilidade, tornando-os ambientalmente adequados. Este estudo avaliou um SAF com 10 anos de implanta??o, gerando informa??es sobre quanto as culturas de leguminosas fixadoras de nitrog?nio influenciaram nas propriedades qu?micas do solo e na produ??o do sistema, quantificando a produ??o de palmito, o crescimento de plantas de Khaya ivorensis A. Chevalier e Euterpe oleracea Mart. plantados e o cultivo de feij?o. O experimento estava localizado no Campo Experimental da Embrapa Agrobiologia, no munic?pio de Serop?dica, do Rio de Janeiro. O delineamento experimental adotado foi o de blocos ao acaso com cinco tratamentos e quatro repeti??es, com parcelas de 9 m x 9 m cada, totalizando 1.620 m2. Em todos os tratamentos existiam a?a?s plantados de 3 m x 3 m ao longo de todas as parcelas que tamb?m continham um mogno africano no centro de cada uma. Os tratamentos foram compostos por aduba??es verdes nas entrelinhas dos a?a?s, constitu?dos por Acacia angustissima (Mill.) Kuntze; Gliricidia sepium (Jacq.) Steud.; p aduba??o nitrogenada de cobertura com torta de mamona e o controle com vegeta??o espont?nea. Para avalia??o qu?mica do solo foram feitas duas coletas, uma antes e outra p?s manejo da biomassa vegetal. Foi realizada a biometria das plantas de mogno africano, de a?a?, e a quantifica??o da produ??o de palmito, onde foi poss?vel perceber que essas culturas tiveram o crescimento prejudicado devido a falta de manejo, tendo em vista que houve menos competi??o nas parcelas sem leguminosas arb?reas, onde essas culturas de interesse atingiram maiores di?metros e alturas, refletindo da mesma forma na produ??o de palmito. A aduba??o verde foi eficiente na ciclagem de nutrientes do solo, aumentando o teor da maioria dos elementos ap?s um manejo e superando vegeta??o espont?nea al?m de ter beneficiado a produ??o do feijoeiro. A inocula??o com extrato de n?dulos ? capaz de aumentar a nodula??o e o teor de nitrog?nio da parte a?rea do feijoeiro, por?m n?o aumentou a produ??o de gr?os.

Submitted by Natalie Mendes (nataliermendes@gmail.com) on 2015-11-12T22:45:09Z No. of bitstreams: 1 Vers?o corrigida - vers?o final.pdf: 1423044 bytes, checksum: 6989a397b0d890ed1cb80eaaf86dcd52 (MD5) / Made available in DSpace on 2015-11-12T22:45:09Z (GMT). No. of bitstreams: 1 Vers?o corrigida - vers?o final.pdf: 1423044 bytes, checksum: 6989a397b0d890ed1cb80eaaf86dcd52 (MD5) Previous issue date: 2013-03-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Nifurtimox and benznidazole have been used to treat Chagas? disease since the 70s. Both drugs can induce side effects on the patients and are not effective when given during the chronic phase. Therefore, more efficient drugs with lower toxicity are needed for the treatment of this disease. The synthesis of complexes of transition metals, especially ruthenium has been increased over the years due to the interest in the biological applications of these compounds. The present study aimed to evaluate the activity of anti-Trypanosoma cruzi of nitro/nitrosyl ruthenium complexes, cis-[RuCl(NO2)(dppb)(5-mebipy)] (1), cis-[Ru(NO2)2(dppb)(5-mebipy)] (2), ct-[RuCl(NO)(dppb)(5-mebipy)](PF6)2 (3) and cc-[RuCl(NO)(dppb)(5-mebipy)](PF6)2 (4). We evaluated the cytotoxicity, anti-T. cruzi activity in vitro and in vivo, and inhibition of cruzain enzyme activity. We also evaluated the mechanism of action of compound 3, the most active among the others. All compounds showed low cytotoxicity and trypanocidal activity against the three evolutionary forms of the parasite. Only compound 1 did not inhibit the epimastigote form. Regarding the enzymatic activity, compound 2 was the only one who did not inhibit the cruzain activity. Treatment with compound 3 caused changes in the membrane and vacuoles of the parasites, correlated to positive stains for propidium iodide and monodansylcadaverine, respectively. Moreover, the treatment with compound 3 caused a reduction of parasitemia and increased survival of infected mice. Thus, the nitro/nitrosyl ruthenium complexes represent a potential class of drugs for the treatment of Chagas' disease. / Os f?rmacos nifurtimox e benzonidazol t?m sido utilizados no tratamento da doen?a de Chagas desde os anos 70. Ambos podem induzir efeitos colaterais nos pacientes e n?o possuem efic?cia na fase cr?nica. Portanto, se torna necess?ria a identifica??o de medicamentos mais eficientes e menos t?xicos para o tratamento desta doen?a. A s?ntese de complexos de metais de transi??o, especialmente o rut?nio, tem sido intensificada ao longo dos anos devido ao interesse nas aplica??es biol?gicas destes compostos. Este estudo teve, como objetivo, avaliar a atividade anti-Trypanosoma cruzi dos nitro/nitrosilo complexos de rut?nio, cis-[RuCl(NO2)(dppb)(5-me93bipy)] (1), cis-[Ru(NO2)2(dppb)(5-mebipy)] (2), ct-[RuCl(NO)(dppb)(5-mebipy)](PF6)2 (3) e cc-[RuCl(NO)(dppb)(5-mebipy)](PF6)2 (4). Foram avaliadas a citotoxicidade, a atividade anti-T. cruzi in vitro e in vivo e a inibi??o da atividade enzim?tica da cruza?na. Foi tamb?m avaliado o mecanismo de a??o do composto 3, o mais ativo dentre os demais. Os 4 compostos apresentaram baixa citotoxicidade e atividade tripanocida para as tr?s formas evolutivas do parasito. Apenas o composto 1 n?o inibiu a forma epimastigota. Em rela??o ? atividade enzim?tica, o composto 2 foi o ?nico que n?o inibiu a cruza?na. Em rela??o ao composto 3, os parasitos tratados com este composto apresentaram altera??es na membrana e presen?a de vac?olos correlacionados ?s marca??es positivas para iodeto de prop?dio e monodansilcadaverina, respectivamente. Al?m disso, o tratamento proporcionou redu??o de parasitemia e aumento de sobrevida dos camundongos infectados. Desta forma, os nitro/nitrosilo complexos de rut?nio representam uma classe de f?rmacos em potencial para o tratamento da doen?a de Chagas.

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 IedaNSM.pdf: 5948604 bytes, checksum: dbf245a349dd04cff535e8ba2e89601d (MD5) Previous issue date: 2007-07-06 / The aim of this work was to study a series of 11 different compositions of Ti-Zr binary alloys resistance to aggressive environment, i. e., their ability to keep their surface properties and mass when exposed to them as a way to evaluate their performance as biomaterials. The first stage was devoted to the fabrication of tablets from these alloys by Plasma-Skull casting method using a Discovery Plasma machine from EDG Equipamentos, Brazil. In a second stage, the chemical composition of each produced tablet was verified. In a third stage, the specimen were submitted to: as-cast microstructure analysis via optical and scanning electron microscopy (OM and SEM), x-ray dispersive system (EDS) chemical analysis via SEM, Vickers hardness tests for mechanical evaluation and corrosion resistence tests in a 0.9% NaCl solution to simulate exposition to human saliva monitored by open circuit potential and polarization curves. From the obtained results, it was possible to infer that specimens A1 (94,07 wt% Ti and 5,93% wt% Zr), A4 (77,81 wt % Ti and 22,19 wt % Zr) and A8 (27,83 wt% Ti and 72,17 wt% Zr), presented best performance regarding to corrosion resistance, homogeneity and hardness which are necessary issues for biomaterials to be applied as orthopedic and odontological prosthesis / Este trabalho teve como finalidade estudar uma s?rie de onze ligas met?licas bin?rias, tit?nio zirc?nio, quanto ? capacidade de resistirem ?s deteriora??es sem sofrerem modifica??es de suas propriedades iniciais de massa e superf?cie quando expostas a meios agressivos, como condi??o fundamental para que as mesmas sejam aplicadas como biomateriais. A primeira etapa tratou da confec??o das amostras das ligas em forma de pastilhas, empregando-se o processo de fundi??o Plasma Skull realizado na m?quina Discovery Plasma, produzida no Brasil pela EDG Equipamentos. Na segunda etapa, as amostras confeccionadas foram submetidas aos ensaios para a determina??o da composi??o qu?mica resultante de cada liga da s?rie ap?s a fus?o. E durante a terceira etapa foram feitos os procedimentos de avalia??es das amostras quanto ? homogeneidade e apresenta??o da microestrutura de cada uma das ligas no estado bruto de fus?o, como resultados dos ensaios metalogr?ficos por microscopia ?ptica e microscopia eletr?nica de varredura acoplada a espectroscopia por energia dispersiva de raios-x; quanto ? propriedade mec?nica de dureza medida em escala Vickers (HV); e quanto ?s propriedades qu?micas de resist?ncia ? corros?o, quando expostas em solu??o de cloreto de s?dio 0,9 %, para simular a saliva, empregando-se o monitoramento do potencial de circuito aberto e as curvas de polariza??o. A partir dos resultados obtidos foi poss?vel identificar as pastilhas de composi??es qu?micas A1 (94,07% de Ti e 5,93% de Zr), A4 (77,81% de Ti e 22,19% de Zr) e A8 (27,83% de Ti e 72,17% de Zr) que resultaram como maiores detentoras do conjunto de propriedades de resist?ncia ? corros?o, homogeneidade e dureza, as quais s?o mais necess?rias em biomateriais tipo pr?teses ortop?dicas ou odontol?gicas

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-09-11T19:30:41Z No. of bitstreams: 1 2017 - Marcius Nei Zanin Cesar.pdf: 3447328 bytes, checksum: 098490a3674208d8609db17b18d3c285 (MD5) / Made available in DSpace on 2018-09-11T19:30:41Z (GMT). No. of bitstreams: 1 2017 - Marcius Nei Zanin Cesar.pdf: 3447328 bytes, checksum: 098490a3674208d8609db17b18d3c285 (MD5) Previous issue date: 2009-04-30 / Cap. I The aim of this work is to evaluate the agronomic behavior of different legume species under cerrado conditions in Mato Grosso do Sul. Seven experiments were carried out, all of them in the experimental field of the (Ag?ncia de Desenvolvimento Agr?rio e Extens?o Rural de MS), (Agency of rural development and extension of MS). Two of these experiments referred to the performance of legumes evaluation. The first experiment was carried out during the Spring- Summer period, and the second one during the Fall- Winter period. The treatments were constituted by the legume species (Crotalaria juncea, Crotalaria ochroleuca, Crotalaria mucronata, Crotalaria reviflora, Mucuna pruriens, Mucuna aterrima, Cajanus cajan (L.) Millsp Cv Fava larga and Cv IAPAR Arat? 43 an?o, Canavalia ensiformes and Canavalia brasiliensis). The third experiment was carried out to determine the dry phytomass decomposition rate and the nitrogen release of the species that were evaluated; this happened during the Fall-Winter period, and the treatments were the mulching of the legumes cited above, except C. breviflora, which was severely attacked by Fusarium sp. The experimental design adopted was randomized blocks, with eleven treatments and nine harvest dates disposed with four replicates. The forth and the fifth experiments were carried out in the subsequent year, their aim was qualifying the Biological Nitrogen Fixation (hereinafter called BNF) and determining the isotope discrimination value ?B value?; their treatments were seven legume species previously selected due to their performances on the former experimental actions and three checks, Brachiaria decumbens, Helianthus annuus, and Zea mays cv BR 106, disposed in randomized blocks with four replicates. The sixth and the seventh experiments were carried out to evaluate the performance of the cabbage cv Astrus under organic management in no-tillage system. The treatments of the sixth experiment were maize-velvet bean intercrop. The later was sown in five different times after maize germination, mucuna alone, maize alone, spontaneous vegetation, and cultivation with conventional tillage of the soil. The treatments of the seventh experiment were maize intercropped with Crotalaria juncea, the latter was slashed, slashed and pruned, maize with basic fertilizer, maize with basic and dressing fertilizers, crotalaria alone, maize alone, spontaneous vegetation, and cultivation with conventional tillage of the soil. The experimental design adopted for both experiments was randomized blocks. The evaluation of the aerial phytomass production was determined when the legume species flowered and when the non-legume ones underwent the grain filling process. The quantification of BNF and the determination of the B value were estimated by using natural abundance 15N and the 15N dilution technique. Functional growth analyses were also carried out as well as soil cover rates, digestion time of the plant tissues, and the phytosociology were determined. On the sixth and seventh experiments the green manure contributions on the agronomic behavior of the cabbage cultivated in no-tillage system under organic management were evaluated. The results obtained have demonstrated the viability for the cultivations of these legume species at the Cerrado Biome, with the contribution of the BNF varying between 75 and 85% of the nitrogen found in the plant tissue originating from the air. They have also demonstrated the viability of using C. juncea and velvet bean when both are intercropped with maize in the mulching formation to the organic cultivation of the cabbage in no-tillage system Cap. II Two experiments were carried out to evaluate the agronomic behavior of legume species in which several components of plant growth were evaluated, such as aerial phytomass production, soil cover rate, seed production, besides phytosociology and in situ decomposition rate under cerrado conditions in Mato Grosso do Sul in two periods of the year. One experiment was carried out during the Spring-Summer period and the other one was carried out during the Fall-Winter period. Both experiments were carried out at the Centro de Pesquisa da Ag?ncia de Desenvolvimento Rural e Extens?o Rural de Mato Grosso do Sul (Mato Grosso do Sul Research center of the Agency of rural development and extension), in Campo Grande ? MS. The experimental design adopted for both was randomized blocks, formed by eleven treatments made up by the species C. juncea, C. ochroleuca, C. mucronata, C. spectabilis, C. breviflora, Mucuna aterrima, Mucuna pruriens, Canavalia brasiliensis, Canavalia ensiformis, Cajanus Cajans cv ?IAPAR an?o?, and Cajanus Cajans cv. giant broad bean. The agronomic behavior of the species that were studied was evaluated by the analysis of the stem and the leaf separately. It was observed that the aerial phytomass productions differed significantly with the species of the genus Crotalaria, showing the best results. Crotalaria juncea stands out with 14.16 Mg ha-1, followed by the Cajanus cajan cv. Fava larga with 11.58 Mg ha-1; there were no significant differences among the species of prostrate habit, mucunas and Brazilian jackbean (Canavalia brasiliensis). The later obtained 3.56 Mg ha-1 and the former did 2.85 Mg ha-1. Regarding seed production, the best performances were obtained during the Fall-Winter period for all legume species, except jack bean and feij?o-bravo (Capparis flexuosa), both obtained similar performances on the two periods of sowing, probably because they might be more tolerant to the drought stress. Regarding the decomposition rate, the results have revealed that the decomposition constants and the residue half-lives had different behaviors on the species that were studied; the Crotalaria species obtained higher decomposition rates when compared to the other species, differentiated behaviors were also noticed on the stem and on the leaf. The C. juncea, jack bean, and the two species of mucuna obtained higher soil cover rate, which reflected a higher suppression of spontaneous plants Cap. III Two experiments related to the quantification of BNF and the determination of the isotope discrimination, ?B value?, in legume species previously selected were simultaneously carried out in the experimental field of the AGRAER-MS, in Campo Grande-MS, during the Spring/Summer period in the 2005/2006 year of production. The experimental design adopted was randomized blocks, formed by ten treatments made up by the species C. juncea, C. ochroleuca, C. mucronata, C. spectabilis, velvet bean, Brazilian jackbean, and Pigeon pea; there have been also, as checks, Sunflower, Maize, and Brachiaria species. The aerial phytomass productions were determined when each legume species flowered and when the non-legume ones underwent the grain filling process. With the samples of legumes and check plants, the quantities of N and the BNF were estimated by using the 15N dilution technique. Afterwards, when the BNF values were known, they were applied to the equation used in natural abundance 15N with the aim of estimating the B value. Regarding the aerial phytomass production, the Pigeon pea had the best performance, followed by the C. ochroleuca, reaching averages of 16.24 Mg ha-1 against 14.44 Mg ha-1. The legume species behaved similarly to the amount of accumulated nitrogen; the Pigeon pea, C. ohcroleuca, and C. mucronata reached values of 346.57 kg ha-1, 333.25 kg ha-1, and 277.35 kg ha- 1 respectively, and they deserve a distinction. Regarding the %BNF, it was observed that the 15N dilution technique could not be applied in all the species that were studied since the cycle of most legumes species was different from the checks; in this way, the checks were not appropriate because the technique demands that legumes and checks grow simultaneously and under the same conditions. However, to the varieties which were more precocious that the checks, the BNF value must be at least between 73 to 87%. Just on the specie C. mucronata it was possible to estimate the BNF and the B value with the rigor that the applied isotopic methodologies demand. The B value of this specie was -3.69. Cap. IV The aim of this study is to evaluate the agronomic behavior of the cabbage in no-tillage system under organic management and the contribution of the prior cultivation of two legumes with different growing habits intercropping with maize in the mulching formation. Both experiments were carried out in the experimental field of AGRAER-MS, in Campo Grande-MS. The first experiment was the maize-C. juncea intercrop, the latter was managed, slashed, pruned, and slashed afterwards; besides the cultivation of single maize, single C. juncea, cultivation with conventional tillage of the soil with and without fertilization with equivalent amounts of 100 Kg N ha-1 at planting and sidressed 30 days after the maize cultivation, making up eight treatments with four replications in randomized blocks. The dry matter productions in the aerial part of the cover crops and the spontaneous vegetation were evaluated. Agronomic characteristics that were evaluated on the cabbage: productivity, commercial standard, fresh and dry weight, besides the dry phytomass of the prior cultivation. On this experiment it was possible to verify better yields regarding the fresh weight and head diameter when we used single, pruned C. juncea maize with basic fertilizer, and maize with base and dressing fertilizers, reaching a fresh weight over 1.0 Kg and heads diameter over 10 cm. Regarding maize and cabbage productivity, they were not influenced by the different kinds of intercrop systems; there were no significant statistic difference of treatments, which also reflected on the dry matter production of the prior cultivations. On the second experiment, the experimental design which was adopted was randomized blocks, with nine treatments and four replicates. The treatments were: maize-velvet bean intercrop, the later was planted in five different times: after the maize germination, maize alone, mucuna alone, cultivation with conventional tillage of the soil, and fallow with spontaneous vegetation, making up a total number of nine treatments. The parameters that were evaluated were similar to the ones of the former experiment.The cabbage production showed the most promising yield 2.06 Kg of head average weight and when cultivated as a sequential crop to the maize-velvet bean intercrop sown 15 days after the maize germination, differing significantly from the other treatments. When we analyzed the maize productivities, we noticed fall of productivity around 29% when it was intercropped with velvet bean at 15 and 30 days after its germination when it was compared to the other prior cultivations in which the intercrop system was used. / Cap. I O presente trabalho teve como finalidade avaliar o comportamento agron?mico de diferentes esp?cies de leguminosas nas condi??es do cerrado de Mato Grosso do Sul. Foram conduzidos sete experimentos, todos no campo experimental da Ag?ncia de Desenvolvimento Agr?rio e Extens?o Rural de MS, sendo que dois deles foram referentes ? avalia??o do desempenho das leguminosas. O primeiro foi instalado no per?odo de primavera-ver?o e o segundo no outonoinverno. Os tratamentos foram constitu?dos das esp?cies de leguminosas Crotal?ria juncea, Crotal?ria ochroleuca, Crotal?ria mucronata, Crotal?ria reviflora, Mucuna pruriens, Mucuna aterrima, Cajanus cajan (L.) Millsp cv Fava larga e Cv IAPAR Arat? 43 an?o, Canavalia ensiformes e Canavalia brasiliensis. O terceiro experimento foi realizado para determinar a taxa de decomposi??o da fitomassa seca e libera??o de nitrog?nio das esp?cies avaliadas, realizado no per?odo de outono-inverno, com os tratamentos constituindo-se da palhada das leguminosas descrita acima, exceto C. breviflora, pois a leguminosa sofreu ataque severo de Fusarium sp. O delineamento experimental foi em blocos ao acaso, com onze tratamentos e nove ?pocas de coleta distribu?dos em quatro repeti??es. O quarto e o quinto experimentos foram realizados no ano subsequente e tiveram como finalidade quantificar a Fixa??o Biol?gica de Nitrog?nio (FBN) e determinar o valor de discrimina??o isot?pica ?Valor B?, tendo como tratamentos sete esp?cies de leguminosas previamente selecionadas pelos seus desempenhos nas a??es experimentais anteriores e tr?s testemunhas, Brachiaria decumbens, Helianthus annuus e Zea mays cv BR 106, dispostos em blocos ao acaso com quatro repeti??es. O sexto e o s?timo experimentos foram conduzidos para avaliar o desempenho do repolho cv Astrus sob manejo org?nico em sistema plantio direto, sendo que o sexto experimento teve como tratamentos cons?rcio milho x mucuna cinza, sendo esta semeada em cinco ?pocas diferentes, ap?s germina??o do milho, mucuna em monocultivo, milho em monocultivo, vegeta??o espont?nea e cultivo com preparo convencional do solo. O s?timo experimento teve como tratamentos milho consorciado com Crotal?ria juncea, sendo esta ro?ada, ro?ada e podada, milho com aduba??o de base, milho com aduba??o de base e cobertura, crotal?ria em monocultivo, milho em monocultivo, vegeta??o espont?nea e cultivo com preparo convencional do solo. O delineamento experimental adotado em ambos os experimentos foi o de blocos ao acaso. A avalia??o da produ??o de fitomassa a?rea foi determinada por ocasi?o do florescimento para as esp?cies de leguminosas e de enchimento de gr?os para as n?o-leguminosas. A quantifica??o da FBN e determina??o do valor ?B? foram estimadas utilizando-se a t?cnica de abund?ncia natural 15N e da dilui??o isot?pica de 15N. Foram tamb?m realizadas an?lises funcionais de crescimento, bem como determinadas as taxas de cobertura do solo, tempo de decomposi??o dos tecidos vegetais e a fitossociologia. No sexto e no s?timo experimentos, foram avaliadas as contribui??es da aduba??o verde no desempenho agron?mico do repolho cultivado em sistema de plantio direto, sob manejo org?nico. Os resultados obtidos demonstraram a viabilidade do cultivo destas leguminosas no bioma cerrado, com a contribui??o da FBN, variando entre 75 e 85% do nitrog?nio encontrado no tecido vegetal proveniente do ar. Tamb?m, demonstraram a viabilidade do uso da C. juncea e M. cinza quando cultivadas em cons?rcio com milho para obten??o de palhada ao cultivo org?nico do repolho em sistema plantio direto. Cap. II Dois experimentos foram conduzidos para avaliar o comportamento agron?mico de esp?cies de leguminosas, onde foram avaliados diferentes componentes do crescimento vegetal, como produ??o fitomassa a?rea, taxa de cobertura de solo, produ??o de sementes, al?m da fitossociologia e taxa de decomposi??o ?in situ?, nas condi??es do cerrado de Mato Grosso do Sul, em duas ?pocas do ano. Os experimentos foram conduzidos no Centro de Pesquisa da Ag?ncia de Desenvolvimento Agr?rio e Extens?o Rural de Mato Grosso do Sul, localizado em Campo Grande - MS, sendo um no per?odo de primavera-ver?o e outro no outono-inverno. Em ambos, o delineamento experimental adotado foi o de blocos ao acaso, formado de onze tratamentos constitu?dos das esp?cies C. juncea, C. ochroleuca, C. mucronata, C. spectabilis, C. breviflora, Mucuna aterrima, Mucuna pruriens, Canavalia brasiliensis, Canavalia ensiformis, Cajanus Cajans cv. IAPAR an?o e Cajanus Cajans cv. fava larga gigante. O comportamento agron?mico das esp?cies estudadas foi avaliado analisando-se separadamente haste e folha. Observou-se que as produ??es de fitomassa a?rea diferiram de forma significativa com as esp?cies do g?nero crotal?ria, obtendo-se melhores desempenhos. Destacam-se a Crotal?ria juncea com 14,16 Mg ha-1, seguida do Guandu cv fava-larga com 11,58 Mg ha-1; entre as esp?cies de h?bito prostrado, n?o houve diferen?as significativas, mucunas e o feij?o-bravo-do Cear?, sendo que esse obteve 3,56 Mg ha-1 contra 2,85 Mg ha-1 da M. preta. Com rela??o ? produ??o de sementes, os melhores desempenhos foram obtidos no per?odo de outono-inverno para todas as leguminosas, com exce??o do feij?o-de-porco e feij?o-bravo, que obtiveram desempenhos semelhantes nas duas ?pocas de semeadura, provavelmente, por serem mais tolerantes ao estresse h?drico. No tocante ? taxa de decomposi??o, os resultados revelaram que as constantes de decomposi??o e tempo de meia-vida tiveram comportamentos diferentes para as esp?cies estudadas, com esp?cies de crotal?ria obtendo maiores velocidades de decomposi??o quando comparadas ?s demais esp?cies, notou-se tamb?m comportamentos diferenciados para haste e folha. A C. juncea, feij?o de porco e as duas esp?cies de mucuna obtiveram maior taxa de cobertura de solo, o que refletiu em uma maior supress?o da vegeta??o de ocorr?ncia espont?nea Cap III Foram conduzidos simultaneamente dois experimentos relacionados ? quantifica??o da FBN e determina??o do valor de discrimina??o isot?pica, valor ?B?, em esp?cies de leguminosas previamente selecionadas. Os experimentos foram conduzidos no campo experimental da AGRAER-MS, localizado em Campo Grande-MS, no per?odo de primavera-ver?o, no ano agr?cola 2005/06. O delineamento estat?stico utilizado foi o de blocos ao acaso, constitu?dos de dez tratamentos, sendo este compostos pelas esp?cies C. juncea, C. ochroleuca, C. mucronata, C. spectabilis, Mucuna cinza, Feij?o-bravo-do-cear? e Guandu fava larga; e como testemunhas as esp?cies Girassol, Milho e Braqui?ria. Por ocasi?o do florescimento de cada esp?cie de leguminosa e enchimento de gr?os das n?o-leguminosas, foram determinadas as produ??es de fitomassa a?rea. A partir das amostras de leguminosas e plantas testemunhas, estimaram-se as quantidades de N e a FBN, para tanto usando a t?cnica de dilui??o isot?pica de 15N . Posteriormente, conhecendo-se os valores de FBN, aplicou-se aos mesmos a equa??o utilizada na t?cnica de abund?ncia natural de 15N com a finalidade de estimar o valor B. Com rela??o ? produ??o de fitomassa a?rea, o Guandu fava larga obteve melhor desempenho seguido da C. ochroleuca, atingindo m?dias de 16,24 Mg ha -1 contra 14,44 Mg ha-1. Para a quantidade de nitrog?nio acumulada as esp?cies de leguminosas se comportaram de maneira semelhante, com destaque para o Guandu fava larga, C. ohcroleuca e C. Mucronata, atingido valores de 346,57 kg ha-1, 333,25 kg ha-1 e 277,35 kg ha-1 respectivamente. No tocante ? %FBN, observou-se que a t?cnica de dilui??o isot?pica de 15N n?o poderia ser aplicada para todas as esp?cies estudadas, uma vez que a maioria das esp?cies de leguminosas teve ciclo diferenciado das testemunhas, desta forma, as testemunhas n?o foram apropriadas, visto que a t?cnica exige que tanto as leguminosas como as testemunhas cres?am nas mesmas condi??es e de forma simult?nea. Contudo, para as variedades mais precoces que as testemunhas, o valor de FBN deve estar no m?nimo entre 73 a 87%. Somente na esp?cie C. Mucronata, foi poss?vel estimar a FBN e o valor B com o rigor que exigem as metodologias isot?picas aplicadas. O valor B para esta esp?cie foi de -3,69. Cap. IV O presente estudo teve o objetivo de avaliar o desempenho agron?mico do repolho em sistema plantio direto, sob manejo org?nico, e a contribui??o do pr?-cultivo de duas leguminosas de h?bitos de crescimento distintos em cons?rcio com milho, na forma??o de palhada. Ambos experimentos foram implantados no Campo Experimental da AGRAER, em Campo Grande-MS. O primeiro experimento consistiu no cons?rcio entre milho e C. juncea, sendo esta manejada, somente com ro?ada (taratamento 6), podada e posteriormente ro?ada (tratamento 5), al?m do cultivo do milho solteiro, C. juncea solteira, cultivo com preparo convencional do solo, com aus?ncia e presen?a de aduba??o, em quantidades equivalentes a 100 Kg N ha-1 no plantio e em cobertura 30 dias ap?s plantio do milho, perfazendo oito tratamentos com quatro repeti??es, dispostos em blocos ao acaso. Avaliaram-se as produ??es de mat?ria seca na parte a?rea das plantas de cobertura e da vegeta??o espont?nea. As caracter?sticas agron?micas avaliadas no repolho foram: produtividade, padr?o comercial, peso fresco e seco, al?m da fitomassa seca do pr?-cultivo. Neste experimento, verificaram-se melhores rendimentos quanto ao peso m?dio e di?metro da cabe?a quando se utilizaram C. juncea solteira, C.juncea ro?ada, milho com aduba??o de base e milho com aduba??o de base e cobertura, alcan?ando peso m?dio acima de 1,0 kg e di?metro das cabe?as acima de 10 cm. Quanto ? produtividade do milho e do repolho, estes n?o foram influenciados pelos diferentes tipos de cons?rcios, n?o havendo diferen?a estat?stica significativa entre os tratamentos, o que refletiu tamb?m na produ??o de mat?ria seca dos pr?-cultivos. No segundo experimento, o delineamento experimental utilizado foi o de blocos ao acaso com nove tratamentos e quatro repeti??es. Os tratamentos foram: o cons?rcio entre milho e mucuna cinza, sendo esta plantada em cinco ?pocas diferentes - ap?s a germina??o do milho, monocultivo do milho, monocultivo da mucuna, cultivo com preparo convencional do solo e pousio com vegeta??o espont?nea -, perfazendo um total de nove tratamentos. Os par?metros avaliados foram semelhantes aos do experimento anterior. A produ??o do repolho alcan?ou melhores rendimentos, 2,06 kg de peso m?dio da cabe?a; e, quando cultivado em sucess?o ao cons?rcio milho x M. Cinza, semeada aos 15 dias ap?s germina??o do milho, diferiu significativamente dos demais tratamentos. Ao se analisarem as produtividades do milho, notouse uma queda de rendimento em torno de 29% quando este foi consorciado com M. Cinza, aos 15 e 30 dias ap?s sua germina??o, ao comparar-lo aos demais pr?-cultivos utilizando-se cons?rcios

Cette thèse concerne l'étude des propriétés structurales et magnétiques de nanoparticules magnétiques creuses (HMNPs), coquille et coquille/coquille. Les effets de surface sont exaltés de par la présence des surfaces interne et externe. L'étude expérimentale de HMNPs basée sur des mesures magnétiques et de spectrométrie Mössbauer du 57Fe a montré une structure magnétique complexe. Les HMNPs ayant une épaisseur ultrafine présentent une structure magnétique décrite par 2 sous-réseaux spero-magnétiques opposés, en plus de la présence d’un champ d'échange bias significatif. L'effet de la taille et de l'épaisseur des HMNPs a été également étudié. Les spectres Mössbauer obtenus sous champ magnétique montrent que la structure magnétique est fortement corrélée au rapport surface/volume. Ces résultats expérimentaux ont été confirmés par simulation Monte Carlo. Après optimisation du modèle, l’approche numérique montre d’abord que l'anisotropie de surface Ks gouverne le comportement magnétique des HMNPs et ensuite que la valeur critique de Ks nécessaire pour obtenir une configuration radiale (spike) diminue lorsque la taille des HMNPs augmente. L'étude numérique menée pour différentes tailles et épaisseurs de coquille, a permis de suivre leurs effets sur la structure magnétique des HMNPs. Par ailleurs, l'étude expéri-mentale menée sur des HMNPs shell/shell, montre que le désordre des spins et le champ d'échange bias deviennent plus importants lorsque les HMNPs sont recouvertes d’une coquille antiferromagnétique (NiO). De ces résultats, on peut déduire l'effet du désordre des spins sur les phénomènes d'échange bias dans un tel système. / This thesis concerns the study of structural and magnetic properties of hollow magnetic nanoparticles (HMNPs), shell and shell/shell. These HMNPs present enhanced surface effects resulting from the presence of both inner and outer surface layers. The experimental investigation combining magne-tic measurements and 57Fe Mössbauer spectrometry of such HMNPs has revealed a complex spin magnetic structure. Small HMNPs with ultrathin thickness show highly disordered magnetic structure and the corresponding in-field hyperfine structure can be described by means of 2 speromagnetic antiferromagnetically coupled, in addition to the significant exchange bias phenomenon. The in-field Mössbauer study of the effect of size and thickness of HMNPs shows that the spin disorder is strongly correlated to the surface to volume ratio. Those experimental magnetic behaviors were confirmed using Monte Carlo simulation. Indeed, after improving the numeric model, it is concluded that surface anisotropy Ks has a dominant role in the magnetic behavior of HMNPs and the value of critical Ks necessary to obtain radial (spike) configuration decreases as the size of HMNPs increases, keeping the same thickness. The numeric study for different sizes and shell thicknesses allows the effect of these parameters on the spin structure of HMNPs to be followed. Then, the experi-mental study extended to shell/shell HMNPs indicates that the spin disorder is enhanced in HMNPs with antiferromagnetic shell (NiO) in addition to larger exchange bias field. From those results, one can try to deduce the effect of spin disorder on the exchange bias phenomena in such system.

Made available in DSpace on 2015-03-13T17:08:29Z (GMT). No. of bitstreams: 1 JesimaelAS.pdf: 2490132 bytes, checksum: 0f657a274eca483047a74fdbb2b8e032 (MD5) Previous issue date: 2000-04-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Geological and geophysical studies (resistivity, self potential and VLF) were undertaken in the Tararaca and Santa Rita farms, respectively close to the Santo Ant?nio and Santa Cruz villages, eastern Rio Grande do Norte State, NE Brazil. Their aim was to characterize water acummulation structures in crystalline rocks. Based on geological and geophysical data, two models were characterized, the fracture-stream and the eluvio-alluvial through, in part already described in the literature. In the Tararaca Farm, a water well was located in a NW-trending streamlet; surrounding outcrops display fractures with the same orientation. Apparent resistivity sections, accross the stream channel, confirm fracturing at depth. The VLF profiles systematically display an alignment of equivalent current density anomalies, coinciding with the stream. Based on such data, the classical fracture-stream model seems to be well characterized at this place. In the Santa Rita Farm, a NE-trending stream display a metric-thick eluvioregolith-alluvial cover. The outcropping bedrock do not present fractures paralell to the stream direction, although the latter coincides with the trend of the gneiss foliation, which dips to the south. Geophysical data confirm the absence of a fracture zone at this place, but delineate the borders of a through-shaped structure filled with sediments (alluvium and regolith). The southern border of this structure dips steeper compared to the northern one. This water acummulation structure corresponds to an alternative model as regards to the classical fracture-stream, being named as the eluvio-alluvial trough. Its local controls are the drainage and relief, coupled with the bedrock weathering preferentially following foliation planes, generating the asymmetry of the through / O Estado do Rio Grande do Norte apresenta extensas ?reas onde se sobrep?em clima semi-?rido e terrenos cristalinos. Algumas destas ?reas apresentam cobertura relativamente espessa de solo, o que dificulta ainda mais os trabalhos de loca??o de po?os (para extra??o de ?gua subterr?nea) pelo m?todo tradicional que ? baseado na an?lise de fotografias a?reas e geologia de superf?cie. Esse conjunto de fatos faz com que o ?ndice de insucesso das loca??es seja da ordem de 30%. Este trabalho descreve os resultados de estudos estruturais e geof?sicos, realizados em tr?s localidades do estado, com o objetivo de caracterizar as estruturas acumuladoras de ?gua subterr?nea no cristalino, de modo a compor uma base interpretativa que permita aumentar o ?ndice de sucesso das loca??es de po?os. Os trabalhos estruturais envolveram a coleta de dados de fraturas e folia??es e os trabalhos de geof?sica est?o baseados em dados de eletro-resistividade, potencial espont?neo e VLF(Very Low Frequency). A interpreta??o integrada dos dados estruturais e geof?sicos evidenciou que o modelo riacho-fenda n?o se constitui no modelo ?nico de acumula??o de ?gua no cristalino. Constatou-se a exist?ncia de outra estrutura, muito promissora ao ac?mulo de ?gua nestes terrenos, a qual foi denominada de calha el?vio-aluvionar. As estruturas riacho-fenda e calha apresentam caracter?sticas bem distintas e, portanto, os crit?rios de loca??o em cada estrutura s?o bastante diferentes. Na estrutura do tipo riacho-fenda ocorre a coincid?ncia do riacho com a zona de fratura ou com as suas bordas. As dire??es das fraturas coletadas em afloramentos s?o consistentes com a dire??o do riacho. Al?m disso, ocorre a correla??o de anomalias geof?sicas de um perfil a outro, delimitando a zona fraturada e a sua dire??o. Por outro lado, o modelo calha, proposto neste trabalho, representa uma estrutura de acumula??o de aluvi?o e/ou regolito. Os perfis geof?sicos, principalmente as se??es de resistividade aparente, delimitam muito bem as bordas da estrutura e fornecem uma boa indica??o da topografia do topo do cristalino sobre o qual est?o acumulados os sedimentos. As anomalias geof?sicas detetadas no centro da estrutura calha n?o apresentam continuidade de um perfil para o outro, mas ocorre boa correla??o das anomalias provocadas pela borda da estrutura. A implanta??o da estrutura calha ? fortemente condicionada pela folia??o da rocha: a maior dimens?o da estrutura calha ? paralela ? dire??o da folia??o e a forma e mergulho das bordas da calha s?o controladas pelo mergulho da folia??o. No caso das loca??es em que seja v?lido o modelo riacho-fenda, a utiliza??o do VLF oferece excelente resposta tanto em rela??o ? localiza??o da zona fraturada quanto na determina??o da dire??o do seu eixo de prolongamento. Por outro lado, no caso de loca??es em que seja v?lido o modelo calha, o m?todo de eletro-resistividade, em especial a t?cnica da se??o de resistividade aparente, proporciona a delimita??o das bordas da estrutura, bem como revela os locais da calha que apresentam maior espessura de aluvi?o e/ou regolito

Cette étude est consacrée au développement d’une pile à combustible à oxyde solide (SOFC) de type monochambre. Contrairement à une pile SOFC conventionnelle, le système monochambre fonctionne dans un mélange de gaz hydrocarbure/air ce qui permet de s’affranchir des contraintes d’étanchéités. Le principe de fonctionnement est basé sur la différence d’activité catalytique entre l’anode et la cathode : l’anode doit être sélective à l’oxydation des hydrocarbures et la cathode à la réduction de l’oxygène. La configuration monochambre implique cependant de nouvelles contraintes concernant notamment la stabilité des matériaux sous mélange hydrocarbure/air à haute température.L’objectif de cette thèse est d’optimiser les performances d’une pile monochambre fonctionnant sous mélange méthane/oxygène et d’améliorer la compréhension de ce système.Les différents éléments d’une pile (électrolyte, cathode, anode) ont été caractérisés sous mélange méthane/oxygène. Quatre matériaux de cathodes (LSM, BSCF, SSC, LSCF) ont été comparés au niveau de leur activité catalytique, stabilité, conductivité électrique et résistance de polarisation. Une étude catalytique de l’anode a été réalisée afin d’identifier les réactions chimiques qui se produisent. Une étude de pile complète en géométrie électrolyte support a permis de sélectionner le matériau de cathode LSCF. Cette étude a également mis en évidence la nécessité de diminuer l’épaisseur de l’électrolyte, la géométrie anode support a donc été étudiée. La première pile anode support a présentée une anode inhomogène et un électrolyte poreux. Des travaux ont été menés afin d’homogénéiser l’anode et de diminuer la porosité de l’électrolyte. En optimisant les conditions de fonctionnement (température et rapport CH4/O2), une densité de puissance maximale de 160 mW.cm-2 a été obtenue. / This study is devoted to the development of a single-chamber solid oxide fuel cell. Contrary to a conventional solid oxide fuel cell, a single chamber fuel cell works under a hydrocarbon/air mixture with no more sealing needed. The working principle of this device is based on the difference of catalytic activity between the anode and the cathode: the anode must be selective to hydrocarbon oxidation and the cathode to oxygen reduction. With single-chamber geometry, chemical stability of materials has to be taken into account under hydrocarbon/air mixture at high temperature.The goal of this work is to optimize the performances of a single-chamber cell working under methane/oxygen mixture and to improve this device comprehension.Each part of the cell (electrolyte, anode, cathode) was characterized under methane/oxygen mixture. Four cathode materials (LSM, BSCF, SSC, LSCF) were compared regarding their catalytic activity, stability, electrical conductivity and polarization resistance. The catalytic activity of the anode was studied in order to identify the chemical reactions happening. A study of electrolyte supported cells showed that LSCF material is the most suitable cathode. Furthermore, this study showed that the electrolyte was too thick; the anode supported configuration was studied. The first anode supported cell showed an inhomogeneous anode and a porous electrolyte. From that, a study of the homogeneity of the anode and the densification of the electrolyte was performed. A maximum power density of 160mW.cm-2 was obtained by optimizing the working conditions of the cells (temperature and CH4/O2 ratio).

Made available in DSpace on 2015-04-14T13:47:15Z (GMT). No. of bitstreams: 1 427550 - Anexo A.pdf: 7270834 bytes, checksum: a647836118a56575f6729666d3637e03 (MD5) Previous issue date: 2010-03-29 / Esta pesquisa prop?e-se a reconstruir a hist?ria do munic?pio de S?o Luiz Gonzaga, antiga redu??o jesu?tica da regi?o das Miss?es, no per?odo entre 1880, ano em que a Freguesia de San Luis foi elevada ? categoria de vila, e 1932, momento em que o Col?gio Jesu?tico, um dos pr?dios constru?dos ? ?poca da redu??o, encontrava-se em processo de demoli??o. Defende-se a tese de que, ao longo do processo de urbaniza??o e (re)ocupa??o do lugar da antiga redu??o de S?o Luis, foi sonegada ? cidade que nascia, por iniciativa administrativa e de particulares, a possibilidade de exibir vest?gios de um patrim?nio da humanidade que lhe pertencia, uma vez que o munic?pio integra o conjunto dos Sete Povos das Miss?es.

Made available in DSpace on 2015-04-14T13:47:19Z (GMT). No. of bitstreams: 1 429674.pdf: 17235638 bytes, checksum: fc58656272742dc8472c10b7b84d8027 (MD5) Previous issue date: 2011-01-14 / Nos ?ltimos anos do S?culo XIX e primeiros dec?nios do XX ? poss?vel registrar, em Porto Alegre, um n?mero consider?vel de construtores de origem italiana, nascidos na It?lia ou descendentes, como respons?veis pela conforma??o da cidade que crescia. A partir de um panorama da cultura arquitet?nica do pa?s europeu, o trabalho investiga, identifica e analisa formas e espa?os de sua arquitetura que est?o presentes em edifica??es residenciais de pequena escala (unifamiliares e multifamiliares) e de uso misto (resid?ncia com com?rcio), constituintes do tecido urbano de Porto Alegre na ?poca.