L’objectif de cette thèse est de développer une méthode expérimentale permettant de mesurer simultanément des coefficients de co-diffusion dans les zéolithes, pour des mélanges de paraffines en C6 mono et di-branchées, dont les cinétiques de diffusion sont très différentes. Les espèces sont le 2- et le 3-methyl-pentane (2MP et 3MP) et le 2-2- et le 2-3-dimethyl-butane (22DMB et 23DMB) et l'adsorbant est une silicalite. Cette méthode est basée sur la réponse en sortie d’un lit fixe d’adsorbant à une variation cyclique de la composition à son entrée. La conception d’un modèle faisant intervenir des paramètres cinétiques et thermodynamiques a également être effectuée afin de simuler les courbes de perçages des différents constituants en mélange et sur plusieurs cycles. Les conditions expérimentales sont proches des conditions industrielles, à savoir en phase liquide et à fort taux de remplissage de l’adsorbant (185°C et 35 bars) L’écriture d’un modèle de diffusion, basé sur l’équation de Maxwell-Stefan appliquée au "Dusty Gas Model", dans ces conditions de fonctionnement, implique d’introduire des grandeurs volumiques qui permettent de redéfinir les contraintes liées à la saturation de l'adsorbant. De plus, tout en conservant la simplicité du modèle "Single File Diffusion" (pas de contre-diffusion microporeuse), nous avons montré que la prise en compte d’un flux volumique relatif associé au solide permet de conserver l’indépendance des coefficients de diffusion dans le cristal. Les simulations des courbes de perçage – sur un seul cycle pour les molécules rapides et sur plusieurs cycles pour les molécules lentes – indiquent que les coefficients de diffusion des différents isomères suivent l'ordre suivant : D3MP ˜ D2MP > D23DMB > D22DMB, avec un écart de trois ordres de grandeurs entre le 3MP et le 22DMB, ce qui laisse supposer qu'un procédé de séparation basé sur une sélectivité diffusionnelle peut être envisagé. Cependant, les tests de perçage en condition cyclique permettant de caractériser de manière plus précise le système, il a été possible de mettre en évidence une très lente accumulation du 22DMB au cours des cycles sous certaines conditions opératoires, phénomène qui peut s'avérer indétectable sur un faible nombre de cycles et/ou sur le profils de concentration des autres espèces. Ce phénomène a pour conséquence de diminuer les performances de l'adsorbant, aussi bien d'un point de vue capacitif que d'un point de vue sélectif / The aim of this work is to develop a new experimental method in order to determine simultaneously co-diffusion coefficients in zeolites for mixtures of single- and di-branched C6 paraffins, with totally different diffusion kinetics. The species are 2- and 3-methyl-pentane (2MP and 3MP) and 2-2- and 2-3-dimethyl-butane (22DMB and 23DMB) and the adsorbent is a silicalite. This method is based on the output measurement of an adsorbent column subjected to cyclic variations of its input concentration. The analysis of the mixture experimental breakthrough curves, on several cycles, is carried out using a mathematical model, based on Maxwell-Stefan theory of multi-component diffusion, allowing an estimation of thermodynamic and kinetic parameters. The experimental conditions are close to industrial constraints, i.e. at very high adsorption loading, and in the liquid phase (185°C and 35 bars). This requires to develop a modified Maxwell-Stefan diffusion model, applied to the "Dusty Gas Model", including volume constraints in the crystal which implies to redefine the adsorbent saturation. Moreover, while preserving the simplicity of the "Single File Diffusion" model (no counter-diffusion), a relative volumetric flow of the solid is taken into account, allowing to ensure the independence of the diffusion coefficient of each component in the adsorbent. The Maxwell-Stefan diffusion coefficients for the different isomers, obtained from breakthrough curves simulations – on one cycle for fast diffusing species and several cycles for slow molecules – are in the sequence : D3MP ˜ D2MP, > D23DMB > D22DMB, with a difference of three orders of magnitude between 3MP and 22DMB. This implies that a separation process based on kinetic selectivity can be considered. The cyclic breakthrough experiments, allowing a better characterization of the system, highlight a very slow accumulation of the 22DMB isomer during cycles for specific operating conditions, which may be undetectable on a small number of cycles and on the profiles of the other components.. This phenomenon involves a decrease of the adsorbent performances, in terms of capacity as well as selectivity

Les Polluants Organiques Persistants (POPs), largement présents dans l'environnement via les stations d'épuration des eaux usées (STEP) et l'activité anthropique de l'Homme constituent une source de contamination du milieu aquatique. L'évaluation du risque environnemental de ces composés implique leur analyse chimique quantitative et spécifique et l'estimation de leur origine vis-à-vis des zones contaminées. Cette étude consiste en une analyse qualitative et quantitative, à l'échelle internationale, pour une trentaine de composés organiques représentatifs en termes d'utilisation et pertinents en termes d'impact environnemental. L'approche mise en œuvre intègre une étape de détection et une étape d'évaluation de la toxicité des composés ciblés afin d'estimer leur niveau de risque écotoxicologique. La détection de ces composés dans les matrices sédiments a nécessité la mise au point d'une méthode d'extraction Soxhlet et le développement d'une méthode de détection par GC-MS. La validation de cette méthode a permis de mener à bien une campagne d'échantillonnage de 54 stations répartis sur 4 bassins versants (l'Arc, l'Huveaune, la Durance, l'étang de Berre et le Oued Medjerda), afin d'évaluer le niveau de contamination par les POPs. Ce travail se propose d'effectuer un échantillonnage orienté (avant et après des ouvrages majeurs tels que STEP, Industries …) de sédiments des différents cours d'eaux de la zone Méditerranée et d'étudier à la fois les taux de contamination ainsi que l'origine des POPs. Sur le plan régional et international, ce sujet répond à une demande sociétale forte. / Persistent Organic Pollutants (POPs), largely present in the environment via sewage wastewater (WWTP) and anthropogenic activities are a source of contamination of the aquatic environment. The environmental risk assessment of these compounds involves their specific and quantitative chemical analysis and estimation of their origin next to the contaminated areas. This study was a qualitative and quantitative analysis, internationally, for about thirty organic compounds representative in terms of use and relevant in terms of environmental impact. The approach used incorporates a detection step and a step for evaluating the toxicity of the compounds targeted to estimate their level of ecological risk. The detection of these compounds in the sediment matrix required the development of a Soxhlet extraction method and the development of a method of detection by GC-MS. Validation of this method allowed to carry out a sampling campaign of 54 stations spread over four watersheds (Arc, Huveaune, the Durance, the Etang de Berre and Oued Medjerda), to assess the level of contamination by POPs. This work intends to carry out a guided sampling (before and after major works such as STEP, industries ...) sediments of different rivers in the Mediterranean area and study both infection rates and the origin of POPs. At the regional and international levels, the subject responds to a strong societal demand. Indeed, it is essential to characterize the quality of streams and to estimate their contamination. This work has allowed a consistent inventory level of contamination. The PAH analysis is done by gas chromatography-mass spectrometry (GC / MS).

O presente estudo visou reconstruir o histórico de impactos antrópicos na bacia de drenagem do Lago das Garças durante o século XX por meio da deposição de contaminantes no compartimento sedimentar. O Lago das Garças está localizado em uma unidade de conservação, Parque Estadual das Fontes do Ipiranga (PEFI), inserida em área altamente povoada e urbanizada da cidade de São Paulo. Dois testemunhos de sedimento (LG05-03 e LG05-04, com 70 cm e 65 cm, respectivamente) foram amostrados mediante auxílio de mergulhadores no ponto mais profundo do reservatório, sendo, posteriormente, fatiados a cada 1 cm. Em LG05-03 foram quantificadas as distribuições verticais de carbono orgânico total (COT), nutrientes totais (NT e PT), hidrocarbonetos policíclicos aromáticos (HPA), hidrocarbonetos alifáticos (n-alcanos), bem como foi feita a classificação granulométrica. Em LG05-04 foi determinada a deposição de metais pesados (Co, Cr, Cu, Fe, Mn, Ni, Pb e Zn) e a geocronologia através do isótopo radioativo \'ANTPOT. 210 Pb\', usando o modelo CIC (Constant Initial Concentration). Os dados foram analisados por meio de análises estatísticas multivariadas (ACP: Análise de Componentes Principais). Com base nas tendências dos dados e na ACP, foi possível estabelecer três fases principais: Fase I: 64-43 cm (~1894-1975): caracterizada por baixas concentrações de nutrientes e contaminantes, sendo possível recuperar níveis préindustriais destes compostos, propostos como valores de referência regionais. Ainda, com base na razão C/N e em razões entre n-alcanos, notou-se, nesta fase o predomínio de aporte de matéria orgânica de origem alóctone; Fase II: 43-26 cm (~1975-1990): aumento abrupto das concentrações de metais pesados e HPA traçadores de veículos automotores, marcando o aumento da poluição atmosférica devido ao grande crescimento econômico do município e maior circulação de veículos na região. Ainda, foi observado aumento gradual das concentrações de NT e PT, atribuídos aos despejos de esgotos não tratados oriundos da Secretaria de Agricultura e Abastecimento e da Fundação Parque Zoológico; Fase III: 26-0 cm (~1990-2005): aumento mais acentuado das concentrações de nutrientes devido aos despejos de esgotos, acarretando em maior eutrofia do sistema, registrada pelo perfil do n-\'C IND.17\'. Pico das concentrações de HPA traçadores do uso de carvão mineral associado às atividades de uma siderúrgica vizinha (Siderúrgica J.L. Alipeti), bem como queda das concentrações destes traçadores coincidindo com mudanças no processo industrial da empresa. Ainda nesta fase notaram-se aumentos expressivos dos teores e fluxos dos HPA traçadores de veículos automotores, corroborando o cenário de aumento vertiginoso da frota de veículos na última década. Desse modo, este estudo contribuiu com o cenário nacional em termos de manejo de bacias hidrográficas urbanas, incluindo registros desde a época pré-revolução industrial no Brasil (~1894) até os dias atuais, demonstrando o potencial do uso de testemunhos lacustres no resgate de informações relativas à contaminação de ecossistemas aquáticos associadas às atividades antropogênicas. / Present study aimed to reconstruct the human impact history on the Garças Lake Drainage Basin during the 20th Century based on contaminants deposition on the lacustrine sediment. Garças Lake is located in a preservation area, the Parque Estadual das Fontes do Ipiranga (PEFI), located in a highly populated urban area within the city of São Paulo. Two sediment cores (LG05-03 and LG05-04, 70 cm and 65 cm long) were sampled by divers at the deepest site of the lake, which were sliced at 1 cm intervals. Information for LG05-03 included total organic carbon (TOC), total nutrients (TN and TP), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (n-alkanes) and grain size vertical distributions. Deposition of heavy metals (Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and the geocronology by \'ANTPOT. 210 Pb\', using CIC model (Constant Initial Concentration), were determined in LG05-04. Data were analyzed by multivariate statistic analysis (PCA, principal components analysis). Based on data trends and PCA, it was possible to recognized three main phases: Phase I: 64-43 cm (~1894-1975) characterized by low nutrients and contaminants concentrations, allowing retrieving preindustrial levels of these compounds, which are proposed as regional reference values. Besides, C/N ratio and n-alkanes ratios demonstrated aloctonous organic matter predominance; Phase II: 43-26 cm (~1975-1990) characterized by the abrupt increase of heavy metals and vehicular PAHs concentration, indicating the atmospheric pollution increase, due to the great economic rise experienced by the city of São Paulo over that time and the higher vehicles circulation in the region. Yet, it was observed a gradual increase in nutrient concentration attributed to the untreated sewage inputs from the São Paulo State Department of Agriculture and Provisioning headquarters and the city Zoo; Phase III: 26-0 cm (~1990-2005) characterized by a marked increase in nutrient concentration related to the untreated sewage inputs, leading to the increase of eutrophication, as registered by the n-\'C IND.17\' distribution. A peak of coal PAHs concentration was also noticed, related to a neighbor steel mill (J.L. Aliperti), followed by a subsequent decrease of these compounds, coincident with industrial procedures changes. Besides, there was an expressive increase in vehicular PAHs concentrations, corroborating the scenery of a drastic raise of vehicles in the last decade. The present study contributed to the national scenario towards urban drainage basin management. It included records since preindustrial time (~1894) up to the present, highlighting the potential use of lacustrine sediment on the retrieval of historical environmental changes of aquatic ecosystems and associated anthropogenic impacts.

Existem poucas informações sobre exigências de energia de cervídeos brasileiros, dificultando o sucesso de manejo e reprodução em cativeiro. O conhecimento das exigências de energia também é importante para determinar os recursos necessários para sua conservação em parques e reservas. O primeiro objetivo deste experimento foi estudar as exigências nutricionais do veado catingueiro (Mazama gouazoubira) em cativeiro. O segundo objetivo foi observar o comportamento alimentar do veado-campeiro (Ozotoceros bezoarticus) no Parque Nacional das Emas (PNE), descrevendo qualitativamente e quantitativamente as principais espécies vegetais utilizadas para o aporte de nutrientes. A determinação das exigências de energia para mantença utilizou 8 veados-catingueiro de ambos os sexos em cativeiro e foi desenvolvida através de dois métodos: a)equilíbrio de peso e b)água duplamente marcada (2H2 18º). Os animais foram dosados com água duplamente marcada (111,8 mg/kgPV para 2H2O e 163,1 mg/kgPV para H2 18O) e amostras de sangue foram coletadas em intervalos de 3 dias, até que 3 ou 4 meias– vidas dos isótopos tenham decorrido (atingindo o limite de detecção em aproximadamente 30 dias após a dosificação). As curvas de desaparecimento dos isótopos em função do tempo foram utilizadas para calcular o “turnover" de CO2 e H2O. Os resultados obtidos pelos dois métodos foram semelhantes (111,4 e 112,0 kcal/kg.75.d) comprovando que a técnica da água duplamente marcada pode ser utilizada em estudos nutricionais de cervídeos. Informações de doses (mg/kgPV) e intervalo máximo entre aplicação e coleta de sangue (30 dias), permitem o uso desta metodologia em estudos futuros em vida livre. No PNE, veados-campeiro já monitorados com radio colares, permitiram a observação de seu comportamento alimentar. O experimento foi realizado em duas épocas distintas (inverno e verão). As espécies foram analisadas quanto à composição nutricional, para estimar valores energéticos assim como consumo de minerais e proteína. As contribuições das diferentes espécies que compõem a dieta dos cervídeos foram estimadas para duas populações em vida livre, uma com acesso apenas a espécies nativas (área central do parque) e outra com acesso às espécies cultivadas na periferia do PNE. Os sinais isotópicos do carbono 13 e os perfis de n-alcanos foram utilizados para quantificar a contribuição das diferentes espécies ingeridas. Os resultados indicaram que os veados-campeiro utilizam uma ampla gama de partes e espécies vegetais. Sua dieta é composta por aproximadamente 78 ítens, divididos em brotos (38,5%), folhas (15,4%), flores (17,9%), botões florais (12,8%), frutos e sementes (15,4%); de 55 diferentes espécies nativas e 7 culturas agrícolas. Há grande diferença no padrão de consumo entre as populações no interior do parque e aquelas que tem possibilidade de selecionar plantas cultivadas pelo homem. As espécies agrícolas podem contribuir com até 46,9% da dieta dos cervídeos da periferia do parque. Este trabalho determinou as exigências de energia de cervídeos brasileiros, validou o uso de uma técnica indireta para futuros estudos em vida livre e descreveu as espécies e partes utilizadas como aporte de nutrientes por cervídeos em vida livre. / There are limited data on energy requirements of brazilian cervids. Thus, it is difficult to succeed in their management and reproduction in captivity. Knowing the energy requirements is also important to determine the necessary nutritional resources for their conservation in parks and reserves. The first objective was to study the nutritional requirements of the grey-brocket deer (Mazama gouazoubira) in captivity. The second objective was to observe the feeding behavior of the pampas-deer (Ozotoceros bezoarticus) in the Emas National Park (ENP), describing qualitatively and quantitatively the main vegetal species used to supply these animals with nutrients. The determination of energy requirements for maintenance used 8 gray-brocket deer of both sexes in captivity and was carried through two methods: a)weight equilibrium and b)double-labeled water (2H2 18O). The animals were dosed with double-labeled water (111.8 mg/kgBW for 2H2O and 163.1 mg/kgBW for H2 18O) and blood samples were collected with 3 days interval, until 3 or 4 half lives of isotopes had occurred (reached limit of detection at approximately 30 days after the dosage). The curves of isotopes disappearance as a function of time were used to calculate the turnover of CO2 and H2O. The results obtained from the two methods were similar (111.4 and 112.0 kcal/kg.75.d) proving the double-labeled water technique may be used in nutritional studies of cervids. Information on doses (mg/kgBW) and maximum interval between injection and blood collection (30days), allow the use of this methodology in future studies with free ranging deer. In the national park, pampas-deer already monitored with radio colars, facilitated the observation of their feeding behavior. The experiment was conducted at two distinct seasons (winter and summer). The species were analyzed for the nutritional composition, to estimate energy values as well as mineral and protein consumption. The contributions of the different species to the diet of the cervids were estimated for two free ranging populations of the national park, one with access only to native species (central area of the park) and another with access to the crop species cultivated in the periphery of the park. The isotopic signals of carbon 13 and profiles of n-alkanes were used to quantify the contribution of different species to supply the energy demands. The results indicated that pampas-deer feeds on a broad spectrum parts and vegetal species. Its diet was composed of approximately 78 different parts, divided in sprouts (38.5%), leaves (15.4%), flowers (17.9%), floral buttons (12.8%), fruits and seeds (15.4%); from 55 different native species and 7 agricultural cultures. There is a great difference in the intake selection patterns between populations in the interior of the park and those that have access to cropland and the opportunity to choose feeding on native or cultivated plants. The agricultural species can contribute with up to 46.9% of deer diet of the park periphery. This work determined the requirements of energy of Brazilian cervids, validated the use of one indirect technique for use in free ranging animals and described the species and parts used to supply nutrients to cervids in the wild.

A avaliação da presença de hidrocarbonetos de petróleo em mangue na região entre a Estrada Rio-Santos e o Canal Bertioga ? São Paulo ? Brasil foi realizada através da análise de amostras de sedimento coletadas em testemunhos em épocas distintas (2001 e 2005). O rompimento de um oleoduto em outubro de 1983 derramou 3.000.000 litros de petróleo (também analisado) nesse local. Esse óleo desceu pelo Rio Iriri até atingir o Canal de Bertioga, espalhando-se por cerca de 60 quilômetros. Uma batalha jurídica teve início em 1985 e se encontra atualmente em fase de execução da sentença. Neste trabalho foram descritas algumas questões jurídicas envolvendo o derramamento ocorrido e as análises químicas para serem utilizadas como nexo causal. Os hidrocarbonetos foram analisados através da extração com solvente orgânico em sistema Soxhlet e por cromatografia a gás com detecção de ionização de chama (GC-FID) para n-alcanos e alcanos isoprenóides e com espectrometria de massas (GC-MS) para biomarcadores de petróleo e compostos policíclicos aromáticos (CPAs). Os resultados dos hidrocarbonetos alifáticos somente permitiram avaliar a contribuição de origem petrogênica pela presença de mistura complexa não resolvida (UCM) em algumas amostras de sedimentos. Não foi possível avaliar a contribuição petrogênica nos sedimentos baseado nas concentrações de n-alcanos, de alifáticos totais e as relações pristano/fitano, pristano/n-C17 e fitano/n-C18. A relação entre os homólogos e isômeros dos biomarcadores de petróleo, entretanto, indicou a presença do petróleo derramado no mangue depois de duas décadas. As maiores concentrações dos biomarcadores de petróleo foram encontradas na região mais próxima do derramamento e nos topos dos testemunhos. As análises de CPAs nos sedimentos foram importantes para a identificação de compostos mutagênicos e carcinogênicos provenientes do petróleo derramado no mangue. / The evaluation of the presence of hydrocarbons of oil in mangrove in the region between the Rio-Santos Road and Bertioga Channel - São Paulo - Brazil was carried out through the analysis of sediment samples collected in cores in distinct times (2001 and 2005). The disruption of a pipeline in October of 1983 spilled 3,000,000 of liters of petroleum (also analyzed) in that area. That oil has gone down the Iriri River as far as the Bertioga Channel and has spread for about 60 kilometers. A judicial process has been started in 1985 and nowadays it is in the final phase when the sentence will be given by the law court. In this work some legal issues involving the occurred spilling and the chemical analyses have been described to be used as causal nexus. The hydrocarbons have been analyzed through an organic solvent extraction using Soxhlet apparatus and gas chromatography with flame ionization detection (GC-FID) for n-alkanes and isoprenoids alkanes, and with mass spectrometer (GC-MS) for petroleum biomarkers and polycyclic aromatic compounds (PACs). The analysis of the aliphatic hydrocarbons allowed evaluating only the contribution of petrogenic origin through the presence of unresolved complex mixture (UCM) in some sediment samples. It has not been possible to evaluate the petrogenic contribution in the sediments based on the concentrations of n-alkanes, total aliphatic hydrocarbons and the ratios between pristane/n-C17 and phythane/n-C18. The ratio between petroleum biomarker homologous and isomers has indicated the presence of the oil spilled in the mangrove after two decades. The highest concentrations of the petroleum biomarkers have been found in the region next to the spilling and in the top-core samples. The analyses of CPAs in the sediments have been important to the identification of mutagenic and carcinogenic compounds present in the petroleum spilled in the mangrove.

Les transferts de nitrène représentent un outil synthétique très intéressant pour former simplement une liaison C-N à partir d’une liaison C-H. Notre laboratoire a développé des précurseurs de nitrène chiraux : les sulfonimidamides. Leur utilisation a abouti, en présence de catalyseurs de cuivre et de rhodium, à des réactions d’aziridination d’oléfine et d’amination C-H hautement diastéréosélectives. Ce projet de thèse s’inscrit dans la continuité de ces travaux. Les sulfonimidamides ont pu être combinés avec des complexes scorpionate de cuivre et d’argent, au cours d’une collaboration COST avec le groupe de Pedro Pérez à Huelva, avec de bons résultats pour l’aziridination d’oléfines et l’amination C-H. De même, des nouveaux complexes de cuivre développés dans l’équipe de Didier Bourissou à Toulouse, ont pu être testés avec succès pour l’aziridination de différentes oléfines, dans le cadre d’une collaboration ANR. D’autre part, le champ d’application de la réaction d’amination C-H catalysée par le rhodium a été étendu avec d’excellents résultats à des substrats complexes comme les terpènes et différents éthers d’énol, ainsi qu’à des substrats peu réactifs comme les alcanes. Enfin, des études mécanistiques ont été menées pour tenter d’élucider la nature du transfert de nitrène. Les résultats obtenus sont en faveur d’un mécanisme concerté asynchrone, mais ils ne permettent pas d’exclure définitivement un transfert radicalaire. L’isolement d’un complexe métal-carbène étant supposé plus aisé qu’un complexe métal-nitrène, nous nous sommes tournés vers le développement de carbènes de sulfoximines, analogues carbonés des sulfonimidamides, sans résultat satisfaisant pour le moment. / Catalytic nitrene transfers are useful tools in organic synthesis, to perform the transformation of a C-H bond into a C-N bond. Our group has previously demonstrated that sulfonimidamieds are efficient chiral nitrène precursors. Combined with copper or rhodium complexes, they have allowed to uncover olefin aziridination and C-H amination that occur with high level of stereoselectivity. These PhD studies stand within the framework of this topic. Sulfonimidamides have first been combined with scorpionate copper and silver complexes developed by Pedro Perez in Huelva, to afford either aziridines or C-H amination products in very good yields. In the same way, new copper catalysts developed in the group of Didier Bourissou in Toulouse were evaluated with good results in olefin aziridination. On the other hand, rhodium catalyzed C-H amination has been applied to more complex substrates such as terpenes and enol ethers, as well as to less reactives substrates like alkanes, with excellent results in terms of regio-, chemo-, and stereoselectivity. Mechanistic studies have also been conducted. These point to an asynchronous concerted nitrene transfer, but the involvement of radicals cannot be ruled out. We have finally turned our attention to the formation of carbenes from sulfoximines, which are the carbo-analogs of sulfonimidamides, but without success so far.

The use of ADF as internal Marker of duodenal digesta flow was evaluated, for this the intestinal degradability of fiber was studied. Four Holstein calves (156± 33 kg), fitted with duodenal cannula T simple, and one calve fitted on the rumen, fed diet base with black oat and supplement, was used. Seven feeds were weighted on the polyester bags (7x5,5cm; 25μm) and treated at different ruminal incubation times (12, 24, 36 and 48 hours). After the respective incubations times, the bags were introduced in the duodenum of animals, recovered on the faeces and analyzed. The means of fiber fraction obtained posruminally and on the samples recovered on the faeces, were significantly different (P<0,05). The percent difference was 6,44, 2,07 e 0,90% on DM basis, for NDF, ADF and ADL, respectively. The disappearance of ADL indicated loss of particles through the pores of the bags, thereby the means were corrected for the loss of ADL, improving the regression coefficients and intercept of the regression equations, demonstrating the potential of using the ADF as an internal marker of digesta flow in ruminants. Additionally, was evaluated the duodenal digesta flow on cattle, with different markers. The means obtained from the ADF and ADL were similar, 2,025 and 2,135 kgDM/day, respectively. The n-alkanes presented low fecal recovery (C31= 63,3%; C32=46,7% e C33=75,6%), this may have contributed to the high variability of the results obtained from the n-alkanes. The n-alkane C32 overestimated the duodenal flow of DM, 3,855 kgDM/day. The ADF was useful for to measure the duodenal digesta flow, even small loss was detected, this did not prejudice the assessment. The ADF was efficient for measure digesta flow of DM, differently of the n-alkanes that overestimated (C32) and presented high variability (C31, C32 and C33). / Este estudo foi conduzido com o objetivo de avaliar o potencial do uso de componentes da fibra como marcadores internos e alcanos na estimativa do fluxo duodenal em bovinos. Para tanto foi avaliada a degradabilidade intestinal das frações fibrosas de diferentes alimentos. Foram utilizados quatro bovinos da raça holandesa dotados de cânula tipo T simples no duodeno e um bovino dotado de fistula ruminal, com dieta a base de Aveia Preta e concentrados (60:40). Foram conduzidos ensaios com sete diferentes alimentos, estes sendo submetidos a diferentes tempos de incubação ruminal, (12, 24, 36 e 48 horas). Por meio da técnica dos saquinhos móveis, foi avaliada a degradação intestinal dos alimentos. As médias das frações fibrosas obtidas pós-ruminalmente e recuperadas nas fezes diferiram significativamente de FDN, FDA e LDA (P<0,05). O desaparecimento em percentual da MS foi de 6,44, 2,07 e 0,90%, para FDN, FDA e LDA, respectivamente. No entanto a análise de regressão linear indicou altos coeficientes de determinação para todos os tempos de incubação. O desaparecimento em proporção de FDA e LDA foram estatisticamente iguais em todos os tempos de incubação (P>0,05), indicando perda de partículas pelos poros dos saquinhos. A correção dos teores de FDA, pela perda de LDA não afetou os coeficientes de determinação que permaneceram elevados. A estimativa do fluxo de duodenal de MS com a FDA e a LDA foram similares, 2,025 e 2,135 kgMS/dia, respectivamente. Os n-alcanos apresentaram baixa recuperação fecal (C31= 63,3%; C32=46,7% e C33=75,6%),o que pode ter contribuído para alta variabilidade dos resultados. O C32 superestimou os valores de fluxo duodenal de MS, sendo que fluxo médio obtido pelo C32, corrigido pela excreção fecal do alcano, foi de 3,855 kgMS/dia, enquanto o observado com o FDA foi de 2,065kgMS/dia e 2,135 kgMS/dia com base no LDA. O FDA foi eficiente para medir o fluxo duodenal de MS, , diferentemente do n-alcano dosado, o C32, que superestimou este parâmetro e, como C31 e C33, apresentou resultados com alta variabilidade.

Made available in DSpace on 2014-06-11T19:32:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-20Bitstream added on 2014-06-13T21:05:24Z : No. of bitstreams: 1 morais_jas_dr_jabo.pdf: 409768 bytes, checksum: b454869362f63b6dd4c538254cae1c13 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O trabalho teve por objetivo estimar a ingestão de matéria seca (IMS) e a digestibilidade da matéria seca (DMS) em bovinos alimentados com Brachiaria brizantha cv. Marandu. Para isso, foram realizados 3 experimentos. O primeiro experimento foi conduzido com o objetivo de validar a metodologia dos n-alcanos para estimar a produção fecal, ingestão e digestibilidade em novilhos Nelore alimentados com capim Marandu em duas diferentes idades de rebrota. No segundo experimento, avaliaram-se os efeitos da redução da freqüência de suplementação no desempenho, IMS, DMS e tempo de pastejo de novilhos mantidos em pastagem de capim Marandu de fevereiro a maio de 2006 e onde foi oferecido um suplemento a base de glúten de milho na quantidade de 0,5% do peso corporal/dia. O terceiro experimento foi realizado para verificar as implicações da redução da freqüência de fornecimento da suplementação na fermentação ruminal de novilhos mantidos em pastagem com capim Marandu. Como principais resultados observou-se que o par de alcanos C32:C33 foi adequado para estimar a IMS e o alcano C35 para estimar a DMS. O mês do ano exerceu importante efeito na disponibilidade e composição bromatológica da forragem, na IMS, na DMS, na produção de ácidos graxos de cadeia curta... / The objectives of this work were to estimate the dry matter intake (DMI) and the dry matter digestibility (DMD) in beef cattle feeding Brachiaria brizantha cv. Marandu. For that, 3 experiments were accomplished. In the first experiment, the objective was to analyser the n-alkanes methodology to estimate the faecal production, intake and digestibility in Nelore steers feeding with Marandu grass in two different regrowth ages. In the second experiment, was evaluated the effect of the reduction of the supplementation frequency in the performance, DMI, DMD and grazing time of steers maintained in grazing of Marandu grass of February to May of 2006 and receiving a supplement the base of corn gluten in the amount of 0.5% of the body weight/day. The third experiment was accomplished to verify the implications of the decreasing the frequency of supplementation in the ruminal fermentation of steers maintained in Marandu pasture. Observed that the pair of alkanes C32:C33 was suitable to estimate DMI and the alkane C35 to estimate DMD. The month of the year cause important effect in the forage availability and the bromathologic composition, in the DMI, DMD and short-chain fatty acids production and, consequently, in the performance of bovine in pasture. The supplementation frequency doesn't affect DMI, the digestibility and the performance of bovine... (Complete abstract, click electronic access below)

Les réactions de déshydrogénation oxydante du propane et de l’éthane ont été étudiées respectivement sur des catalyseurs à base d’oxydes alcalino-terreux (OAT) dopés néodyme et des catalyseurs à base d’oxyde de nickel dopés par différents métaux. Deux méthodes de préparation des solides OAT dopés au néodyme ont été comparées. La caractérisation par analyses DRX montre la formation de solutions solides avec des défauts (lacunes, dislocations). La formation d’agglomérats de néodyme a été également observée. Les tests catalytiques réalisés montrent que le dopage au néodyme augmente la conversion du propane avec simultanément une augmentation de la sélectivité. Les catalyseurs à base d’oxyde de nickel sont eux très actifs dans la réaction de déshydrogénation oxydante de l’éthane. L’étude réalisée montre l’absence de formation de solutions solides étendues avec les dopants. L’addition de niobium et des ions oxalates permet l’isolation des sites actifs qui sont des ions O- et entraine une baisse d’activité mais conjointement une forte amélioration de la sélectivité en éthylène. De plus, elle modifie la texture de NiO en augmentant sa surface spécifique ce qui permet d’obtenir de meilleures conversions. La mise au point de ces catalyseurs est compromise par une désactivation: la caractérisation des solides avant et après désactivation par DRX, Raman, XPS, TEM, EDX et TPD de O2 montre que cette désactivation est due à la réduction lente et irréversible des ions Ni3+ entrainant la diminution du nombre des espèces O-. La formation de la phase NiNb2O6 lors de la désactivation a été également observée. / The oxidative dehydrogenations of propane and ethane have been studied on alkaline earth oxides doped with neodymium oxide (AEO) and nickel oxide doped with different metal oxides. Two types of synthesis have been compared for the preparation of AEO+Nd samples. The characterization by XRD showed the formation of solid solutions with different defects (cationic vacancies, dislocations). The formation of agglomerates of neodymium has also been observed. The catalytic testing showed that the presence of neodymium oxide increases both the conversion of propane and the selectivity to propylene. The addition of neodymium oxide increases the basicity of the catalysts, which seems to be beneficial to the selectivity. The nickel oxide based catalysts are very efficient in the oxidative dehydrogenation of ethane. The study shows that there is no formation of extended solid solution. The addition of niobium and oxalates anions leads to the isolation of the active O- sites at the surface of the nickel oxide, which decreases the activity but strongly increases the selectivity to ethylene. Furthermore, it modifies textural properties of nickel oxide increasing its specific surface area leading to better conversions. However, the applicability of this type of catalysts stays under question because of a deactivation that has been evidenced with time on stream. The characterization of the fresh and deactivated catalysts by XRD, Raman, XPS, TEM, EDX and TPD of O2 showed that this deactivation is due to the slow and irreversible reduction of Ni3+ cations leading to a further decrease in number of the O- species. The formation of NiNb2O6 phase during the deactivation has been evidenced.

Hydrocarbon chains are a basic component in a number of systems as diverse as biological membranes, phospholipids and polymers. A better understanding of the physical properties of n-alkane chains should provide a better understanding of these more complex systems. With this aim, vibrational spectroscopy has been extensively used. This technique, sensitive to molecular details, is the only one able to both identify and quantify conformational disorder present in paraffinic systems. To achieve this, methyl deformations have been widely used as "internal standards" for the normalisation of peak areas. However, in the case of n-alkanes with short chain length, such as n-C[44]H[90] for example, the infrared spectra recorded at liquid nitrogen temperature and reported here show the sensitivity of these latter peaks to the various crystal structures formed. Indeed, the main frequencies of the symmetric methyl bending mode were found between 1384 cm[-1] and 1368 cm[-1] as a function of the crystal form. Changes in the frequency of the first order of the L.A.M. present in the Raman spectra were also observed. At higher temperatures, non all-trans conformers, inferred from different infrared bands present in the wagging mode region, were found to be essentially placed at the end of the n-alkane chains. At the monoclinic phase transition, the concentration of end-gauche conformers, proportional to the area of the infrared band at 1342 cm[-1], increases abruptly. On the contrary, in the spectra recorded at liquid nitrogen temperature no such band is observed. We also studied the degree of disorder in two purely monodisperse long chain n-alkanes, namely n-C[198]H[398] and n-C[246]H[494]. The chain conformation as well as the tilt angle of the chains from the crystal surfaces were determined by means of low frequency Raman spectroscopy and S.A.X.S. measurements on solution-crystallised samples. The increase in the number of end-gauche conformers which was expected to occur with the increase of the tilt angle as a function of the temperature was not detected due to a perfecting of the crystals. Indeed, due to successive heating and cooling to -173&deg;C, the concentration of non all-trans conformers was found to decrease within the crystals. Their numbers were found to be up to six times higher in n-C[198]H[398] crystallised in once folded form than when crystallised in extended form. The C-C stretching mode region of the spectra was used to identify the chain conformation and to estimate the length of the all-trans stem passing through the crystal layers at -173&deg;C. The transition between once folded and extended form crystals was indicated by the presence of additional bands in this region at 1089 cm[-1], 1078 cm[-1] and 1064 cm[-1]. Some of those bands may be related to the fold itself. At the same time, a strong decrease of the intensity of the infrared bands present in the wagging mode region was observed. Finally, the triple layered structure proposed on the basis of X-ray measurements obtained from the crystals of a binary mixture of long chain n-alkanes, namely n-C[162]H[326] and n-C[246]H[494], was confirmed from the study of the C-C stretching mode region of the infrared spectra.