This thesis project investigates the granular flow of wood pellets inside a pilot-scale rotary kiln and its impact on the pyrolysis process. The study focuses on two key factors that must be determined to evaluate their effects on pyrolysis: the mass flow rate delivered by the feeding system at different motor frequencies and the mean residence time (MRT) of the wood pellets. The research is divided into two parts: the first characterizes granular flow without heat application, while the second examines the system behavior under high-temperature pyrolysis conditions. For the first part, the mass flow rate was assessed by measuring the emptying time of the feeding silo at different screw velocities. In contrast, the MRT was determinedwith two scenarios: (1) batches of different masses of wood pellets and (2) continuousfeed until a stable solid bed was formed that allowed tracer particle tracking. In the second part of the study, the drum’s rotational speed and fed mass flow rate were varied. Results indicated a direct proportionality between the mass flow rate delivered by the feeding systems and the screw motor frequency. Additionally, the MRT was found to follow an inverse relation with the drum’s rotational speed if the process was done in batches. In contrast, the MRT was 20 minutes at a feeding rate of 51 kg h-1 and a drum’s rotational speed of 0.36 rad s -1 with a continuous feeding process. Finally, the study concludes that the wood pellet feed rate and drum rotational speed significantly influence the pyrolysis process in the rotary kiln. The system remained stable for wood pellets inside the rotary drum, starting with a feeding rate of 8 kg h-1 and scaling up until a maximum of 21 kg h-1. This behavior is evidenced by the direct proportionality between the evolution of flue gas and pyrolysis gas temperatures over time and the necessity to adjust air supply to maintain system stability.

The dust particles generated due to mechanical wear of iron ore pellets and clusters formed in molten stainless steel alloyed with rare earth metals (REM) are considered in this study. Firstly, the influence of the characteristics of iron ore pellets, applied load on a pellet bed and partial reduction of the pellets on the size distribution of the generated dust was investigated. Secondly, REM clusters are investigated to evaluate the size distribution of the clusters. Also, an extreme value distribution (EVD) analysis has been applied for the observed REM clusters. The large sized pellets showed 10-20% higher wear rate than small sized pellets during wear in a planetary mill. Moreover, an increase of ~67% was observed in the friction and dust generation in the pellet bed as the applied load increased from 1 to 3 kg. Also, it was observed that a higher friction in the pellet bed can lead to an increased amount of airborne particles. The mechanical wear experiments of pellets reduced at 500 °C (P500) and 850 °C (P850) showed that P500 pellets exhibit ~16-35% higher wear rate than unreduced pellets. For the P850 pellets, the wear is inhibited by formation of a metallic layer at the outer surface of the pellets. The mechanism of dust generation has been explained using the obtained results. A reliable cluster size distribution of REM clusters was obtained by improving the observation method and it was used to explicate the formation and growth mechanism of REM clusters. The results show that the growth of clusters is governed by different types of collisions depending on the size of the clusters. For EVD analysis three different size parameters were considered. Moreover, using the maximum length of clusters results in a better correlation of EVD regression lines compared to other size parameters. Moreover, a comparison of predicted and observed maximum lengths of clusters showed that further work is required for the application of EVD analyses for REM clusters. / Studien fokuserar på två olika typer av mikropartiklar som är valda från olika delar av järn- och ståltillverkningsprocessen. Dessa partiklar är dels stoft som genereras på grund av mekanisk nötning av partiklar och dels klusters som bildas i flytande rostfria stål legerade med sällsynta jordartsmetaller (REM). Inledningsvis så undersöktes inverkan av tre faktorer på storleksfördelningen hos stoft som bildas vid hantering av järnoxidpellets. De undersökta faktorerna inkluderade karakteristiken hos järnoxidpellets, det applicerade trycket på pelletsbädden och den partiella reduktionen av järnoxidpellets. Därefter så utfördes tredimensionella undersökningar av REM kluster som extraherats med hjälp av elektrolytisk extraction för att bestämma storleksfördelningen hos klustren. Dessutom så utfördes en extremvärdesdistribution (EVD) studie för de studerade klustren. En planetkvarn användes för att undersöka inverkan of karakeristiken hos pellets på stoftbildningen. Resultaten visade att storleken på pellets kan påverka nötningshastigheten under dessa försöksförhållanden. Pellets som hade en större storlek (13.5&lt; Deq &lt;15.0 mm) uppvisade en 10 till 20% högre nötningshastighet i jämförelse med mindre pellets (9.5&lt; Deq &lt;12.5 mm). Baserat på analyserna av stoftet som genererades under nötningsexperimenten så konstaterades att nötningsmekanismerna för dessa pellets var abrasions- och kollisionsnötning. En pelletsbädd skapades för att möjliggöra studier av inverkan av ett applicerat tryck på stoftbildningen och friktionskrafterna i en pelletsbädd. Ett varierat tryck på mellan 1 till 3 kg applicerades på pelletsbädden. Resultaten visade att en ökning på ~67% av friktionskraften och stoftbildningen ägde rum när det applicerade trycket ökades från 1 till 3kg. Dessutom så visade resultaten att en högre friktionskraft i pelletsbädden kan resultera in en ökad mängd luftburna partiklar. Den mekaniska nötningen av pellets som reducerats vid 500 °C (P500) och 850 °C (P850) studerades också genom användande av en planetkvarn. Resultaten visade att P500 pellets uppvisade en ~ 16 till 35% högre nötningshastighet i jämförelse med oreducerade referenspellets.  Resultaten för P850 pellets visade att den mekaniska nötningen motverkades genom bildningen av ett metalliskt skikt på den yttre delen av pelletsen. Resultaten visade också att stoftet som bildats pga mekanisk nötning av reducerade pellets innehöll 3 till 6 gånger mer grova partiklar  (&gt;20µm) i jämförelse med stoft som bildats från oreducerade pellets. Slutligen så diskuterades hur dessa resultat kan relateras till industriella förhållanden med avseende på mekanismerna som är involverade i den mekaniska nötningen av pellets samt med avseende på relationen mellan hastigheten av de utgående gaserna och storlken och morfologin hos stoftpartiklarna. Klusters innehållande REM-oxider som extraherats från en 253MA rostfri stålsort undersöktes med användande av en tredimensionell teknik. En trovärdig storleksfördelning av klusters (CSD) erhölls genom att förbättra undersökningsmetoden och denna användes för att studera bildningen och tillväxten av REM oxider. Dessutom så användes cirkularitetsfaktorn hos klusters för att dela in klustren i två olika grupper, vilka bildas och tillväxer enligt olika mekanismer. Resultaten visade också att tillväxten av klusters gynnas av olika typer av kollisioner som beror av av storleken på klusters. För REM-klusters så drogs slutsatsen att turbulenta kollisioner är den huvudsakliga mekanismen som påverkar tillväxten. Avhandlingen behandlar även problemet om hur det är möjligt att hantera synfält där det inte förekommer kluster vid en extremvärdesdistribution (EVD) analys. Tre olika parametrar undersöktes i EVD analysen. Resultaten visar att om den maximala längden på kluster (LC) används i analysen så erhålls den bästa korrelationen gällande regressionslinjen för en EVD analys. Specifikt så var R2 värdet upp till 0.9876 i jämförelse med de andra storleksparametrarna som har värden i intervallet 0.9656 – 0.9774. Slutligen så visar resultaten från en jämförelse mellan beräknade och observerade maximala klusterlängder att EVD analyser för studier av REM kluster behöver undersökas ytterligare i framtiden. / <p>QC 20161128</p>

Os grânulos plásticos são encontrados no ambiente marinho e, em função de suas características podem concentrar e transportar poluentes orgânicos. A Enseada de Santos representa um polo de grande importância econômica para o estado de São Paulo, devido à existência do Porto de Santos e do complexo industrial de Cubatão nos seus arredores. Essa região foi escolhida para o desenvolvimento deste estudo por possuir uma grande quantidade de grânulos na superfície arenosa de suas praias. O presente estudo teve como objetivos: (1) avaliar uma proposta metodológica para a coleta de grânulos plásticos, baseada no uso de transectos perpendiculares à linha da água compostos por escavações (amostragens) equidistantes; e (2) analisar a concentração, composição e fontes de contaminação de hidrocarbonetos policíclicos aromáticos (HPAs) nos grânulos coletados em praias arenosas, considerando diferentes escalas espaciais e a influência do tipo de resina que os grânulos são produzidos, bem como o tempo de exposição destes no ambiente. O resultado da avaliação da proposta metodológica determinou o diâmetro do trado que fornece a melhor combinação entre tempo e volume de sedimento coletado, além da confirmação da profundidade de maior ocorrência dos grânulos na coluna sedimentar, bem como a constatação de que transectos tornam-se inviáveis para este procedimento. É sugerido, então, o desenvolvimento de estudos futuros a fim de encontrar o melhor desenho amostral, uma vez que não foi eficaz a realização de transectos, para a amostragem de grânulos plásticos em profundidade. De acordo com os resultados das análises, a concentração e composição de HPAs nos grânulos plásticos variaram de forma expressiva entre os pontos amostrais em uma mesma praia, de forma que, para a obtenção da real variabilidade de poluentes em uma praia, são necessárias coletas em diversos pontos amostrais, a fim de evitar uma equivocada extrapolação dos resultados. As análises dos grânulos coletados em diferentes profundidades no sedimento arenoso indicam resultados semelhantes, com uma alta variabilidade na composição e concentração de HPAs. Entre as resinas, houve diferença na concentração de HPAs (polietileno > polipropileno) e no tempo de exposição, com maiores concentrações nos grânulos mais escuros, ou seja, mais tempo expostos no ambiente. A contaminação na área de coleta é oriunda da mistura de compostos provenientes de fontes petrogênicas e pirolíticas e as análises da potencial toxicidade dos HPAs em grânulos, em geral, indicam um risco iminente aos organismos. São necessários, no entanto, estudos complementares também para a investigação da possibilidade de bioacumulação dos poluentes em organismos. / Plastic pellets are easily found in marine environment and due to its characteristics they may concentrate and bring organic pollutants. Santos bay represents a major economic center for the state of São Paulo because of Santos Port and the Cubatão industrial complex in its surroundings. This place was chosen for the development of the study for the great number of pellets found in the sandy surface of its beaches. This study aimed at (1) evaluating a sampling methodology for plastic pellets based on the use of transects perpendicular to the seawater line and made by diggings equally distant from one another (samplings). It also aimed at (2) analyzing the concentration, composition and sources of polycyclic aromatic hydrocarbons (PAH) contamination on the pellets sampled on sandy beaches, considering different spatial scales and resin kinds which the plastic pellets were made from as well as their exposure time in the environment. As a result of the evaluation of sampling methodology the sampler diameter was defined which provides the best combination between the time and the volume of sampled sediment. Apart from that the depth of the major occurrence of plastic pellets in the sedimentary column was confirmed and it was established that transects are impracticable for this kind of procedure. The development of future studies in order to figure out the best sample design is suggested once the use of transects was not efficient for plastic pellets sampling in depth. According to analyses results the PAHs concentration and composition on the plastic pellets vary largely among sampling sites on the same beach. In order to obtain real pollutant variability on one beach, samples taken from different sampling sites are necessary to avoid a wrong over sizing of results. The plastic pellets analyses taken from different depths in sandy sediment showed similar results to those from the surface with a high variability in PAH concentration and composition. Among the resins there was a difference on PAH concentration (polyethylene > polypropylene) and exposure time, showing larger concentrations on darker pellets, that is longer exposed in the environment. The contamination in the studied area comes from the mixture of compounds from petrogenic and pyrolitic sources and the PAHs potential toxicity in plastic pellets analyses generally reflect an imminent risk to organisms. Complementary studies are also necessary to investigate the possibility of pollutant bioaccumulation in organisms.

Durante a produção do aço a partir da fusão de sucatas em fornos elétricos a arco é gerado entre 10 e 20 kg de resíduos por cada tonelada de aço fundido constituídos por fumos e poeiras contendo óxidos principalmente de ferro, zinco, cálcio e chumbo, tornando-os altamente perigosos e tóxicos. Na procura de uma solução para mitigar problemas de descarte desses resíduos, propõe-se a aglomeração da poeira de aciaria elétrica (PAE) na forma de pelotas auto-redutoras. Essas últimas, são tratadas termicamente pelo processo Waelz o qual consiste em um forno rotativo, alimentado pelas pelotas, e que recupera o zinco por meio de reações metalúrgicas de redução e oxidação. No presente trabalho avaliou-se o comportamento cinético e mecânico bem como as mudanças microestruturais, através do planejamento fatorial fracionário de experimentos tipo 3III(4-2), variando aglomerante, redutor, temperatura e basicidade binária. As técnicas empregadas para caracterização foram: MEV, EDS, DRX, FRX, DTA-TG, análise C-N-H e análise granulométrica a laser. A PAE estudada apresenta 37, 50 % de ferro na forma de hematita e 19, 40 % de zinco na forma de zincita. A maior parte das partículas apresentaram uma morfologia esférica com tamanho aproximado de 1 ?m. Através do método de tempo reduzido foram testados os modelos: (i) modelo de reação química de interface-simetria esférica, (ii) modelo exponencial de reação contínua e (ii) modelo do núcleo não reagido; resultando em um comportamento cinético com a combinação dos dois primeiros modelos. Entre 800 e 950 °C, foi detectada a formação de agulhas de óxido de zinco com impurezas de cloretos e chumbo. Os estudos do comportamento mecânico, após os tratamentos térmicos, apontaram para todas as temperaturas, um melhor comportamento no caso das pelotas aglomeradas com xarope de glicose e Ca(OH)2. / Steel production from scrap melting in electric arc furnaces, generates about 10 to 20 kg of waste per metric ton of molten steel, which are composed by fumes and dust containing mainly oxides of iron, zinc, calcium and lead. Thus, these residues are highly dangerous and toxic. To find ecofriendly solutions and mitigate problems of the solid waste, it was proposed to agglomerate electric steel dust (PAE) in the form of self-reducing pellets. The latter are thermally treated by the Waelz process, which consists of a rotary kiln fed by the pellets, recovering the zinc by means of reduction and oxidation metallurgical reactions. In this study, kinetic and mechanical behavior, as well as microstructural changes, were evaluated by fractional factorial design of type 3III experiments (4-2), varying: binder, reducer, temperature and binary basicity. Chemical and microstructural characterization were performed using: Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction XRD, X-ray fluorescence spectrometry (FRX), differential thermal analysis/thermogravimetric (DTA/TG), elemental analysis C-N-H and laser granulometric analysis. The PAE studied presented 37. 50 % of iron in the form of hematite and 19. 40 % of zinc in the form of zincite. Most of the particles showed a spherical morphology of ~1 ?m in size. Using the time-reduced method, the following models were tested: (i) spherical interface-symmetry reaction model; (ii) exponential continuous reaction model; and (ii) unreacted core model. The results obtained showed a kinetic behavior with the combination of the first two models. At 800 and 950 °C the formation of zinc oxide needles was observed, in which was detected chloride and lead impurities. Mechanical behavior studies after the heat treatments showed that the pellets agglomerated with glucose syrup and Ca(OH)2 presented the best behavior at all temperatures.

Os grânulos plásticos são encontrados no ambiente marinho e, em função de suas características podem concentrar e transportar poluentes orgânicos. A Enseada de Santos representa um polo de grande importância econômica para o estado de São Paulo, devido à existência do Porto de Santos e do complexo industrial de Cubatão nos seus arredores. Essa região foi escolhida para o desenvolvimento deste estudo por possuir uma grande quantidade de grânulos na superfície arenosa de suas praias. O presente estudo teve como objetivos: (1) avaliar uma proposta metodológica para a coleta de grânulos plásticos, baseada no uso de transectos perpendiculares à linha da água compostos por escavações (amostragens) equidistantes; e (2) analisar a concentração, composição e fontes de contaminação de hidrocarbonetos policíclicos aromáticos (HPAs) nos grânulos coletados em praias arenosas, considerando diferentes escalas espaciais e a influência do tipo de resina que os grânulos são produzidos, bem como o tempo de exposição destes no ambiente. O resultado da avaliação da proposta metodológica determinou o diâmetro do trado que fornece a melhor combinação entre tempo e volume de sedimento coletado, além da confirmação da profundidade de maior ocorrência dos grânulos na coluna sedimentar, bem como a constatação de que transectos tornam-se inviáveis para este procedimento. É sugerido, então, o desenvolvimento de estudos futuros a fim de encontrar o melhor desenho amostral, uma vez que não foi eficaz a realização de transectos, para a amostragem de grânulos plásticos em profundidade. De acordo com os resultados das análises, a concentração e composição de HPAs nos grânulos plásticos variaram de forma expressiva entre os pontos amostrais em uma mesma praia, de forma que, para a obtenção da real variabilidade de poluentes em uma praia, são necessárias coletas em diversos pontos amostrais, a fim de evitar uma equivocada extrapolação dos resultados. As análises dos grânulos coletados em diferentes profundidades no sedimento arenoso indicam resultados semelhantes, com uma alta variabilidade na composição e concentração de HPAs. Entre as resinas, houve diferença na concentração de HPAs (polietileno > polipropileno) e no tempo de exposição, com maiores concentrações nos grânulos mais escuros, ou seja, mais tempo expostos no ambiente. A contaminação na área de coleta é oriunda da mistura de compostos provenientes de fontes petrogênicas e pirolíticas e as análises da potencial toxicidade dos HPAs em grânulos, em geral, indicam um risco iminente aos organismos. São necessários, no entanto, estudos complementares também para a investigação da possibilidade de bioacumulação dos poluentes em organismos. / Plastic pellets are easily found in marine environment and due to its characteristics they may concentrate and bring organic pollutants. Santos bay represents a major economic center for the state of São Paulo because of Santos Port and the Cubatão industrial complex in its surroundings. This place was chosen for the development of the study for the great number of pellets found in the sandy surface of its beaches. This study aimed at (1) evaluating a sampling methodology for plastic pellets based on the use of transects perpendicular to the seawater line and made by diggings equally distant from one another (samplings). It also aimed at (2) analyzing the concentration, composition and sources of polycyclic aromatic hydrocarbons (PAH) contamination on the pellets sampled on sandy beaches, considering different spatial scales and resin kinds which the plastic pellets were made from as well as their exposure time in the environment. As a result of the evaluation of sampling methodology the sampler diameter was defined which provides the best combination between the time and the volume of sampled sediment. Apart from that the depth of the major occurrence of plastic pellets in the sedimentary column was confirmed and it was established that transects are impracticable for this kind of procedure. The development of future studies in order to figure out the best sample design is suggested once the use of transects was not efficient for plastic pellets sampling in depth. According to analyses results the PAHs concentration and composition on the plastic pellets vary largely among sampling sites on the same beach. In order to obtain real pollutant variability on one beach, samples taken from different sampling sites are necessary to avoid a wrong over sizing of results. The plastic pellets analyses taken from different depths in sandy sediment showed similar results to those from the surface with a high variability in PAH concentration and composition. Among the resins there was a difference on PAH concentration (polyethylene > polypropylene) and exposure time, showing larger concentrations on darker pellets, that is longer exposed in the environment. The contamination in the studied area comes from the mixture of compounds from petrogenic and pyrolitic sources and the PAHs potential toxicity in plastic pellets analyses generally reflect an imminent risk to organisms. Complementary studies are also necessary to investigate the possibility of pollutant bioaccumulation in organisms.

O presente trabalho teve como objetivos produzir um extrato seco de Ilex paraguariensis por spray-drying, em escala semi-industrial, e desenvolver grânulos esferoidais a partir do extrato seco, pelo método de extrusão/esferonização, bem como caracterizar as propriedades físicas, químicas e tecnológicas e investigar a estabilidade dos principais constituintes polifenólicos de ambos produtos frente à radiação UVC e ao calor. O extrato seco apresentou partículas esféricas (tamanho médio de 19,6 μm), com superfície lisa, boas propriedades de fluxo e rendimento satisfatório (67 %). No teste de fotoestabilidade, o extrato seco se manteve estável frente à radiação UVC, por 48 h, nos diferentes materiais de acondicionamento (frascos de vidro âmbar, frascos de vidro transparente ou vidros de relógio). No teste de estabilidade acelerada (40 ºC, 75 % de umidade relativa, 4 meses), o extrato seco demonstrou ser higroscópico e sensível ao calor, especialmente quando acondicionado em frascos de polietileno, por serem permeáveis à umidade. Os grânulos esferoidais, por sua vez, apresentaram tamanho médio de 1,10 mm, forma e rendimento (78,7 %) satisfatórios, boa dissolução em água (89,44 a 100,05 %) e adequada recuperação (> 95 %) do conteúdo de polifenóis totais em relação ao extrato seco. Os grânulos esferoidais foram estáveis frente à radiação UVC quando acondicionados em frascos de vidro âmbar, entretanto, o teor de polifenóis totais foi reduzido quando as amostras foram acondicionadas em vidro de relógio ou em frascos de vidro transparente. No teste de estabilidade acelerada, os grânulos esferoidais demonstraram ser higroscópicos e sensíveis ao calor. Este efeito foi mais pronunciado quando as amostras foram acondicionadas em frascos permeáveis (de polietileno) do que em frascos impermeáveis (de vidro transparente). Os resultados apontam para a importância da redução da umidade residual tanto do extrato seco quanto dos grânulos esferoidais, bem como para a necessidade de acondicioná-los em embalagens com proteção contra a umidade e a luz, sob baixas temperaturas. / The present work was designed to produce a dry extract of Ilex paraguariensis by the spray-drying process, in semi-industrial scale, and to develop pellets from dry extract, by the extrusion/spheronization method, as well as to characterize the physical, chemical and technological properties and to investigate the stability of the main polyphenol constituents from both products against UVC radiation and heat. The dry extract presented spherical particles (mean size of 19.6 μm), with smooth surface, good flow properties and satisfactory yield (67 %). In the photo stability test, the dry extract remained stable against UVC radiation, for 48 h, in all packaging material (amber glass bottles, transparent glass bottles or open-dishes). In the accelerated stability testing (40 ºC, 75 % relative humidity, 4 months), the dry extract demonstrated to be hygroscopic and sensible to the heat, especially when conditioned in polyethylene ethyl bottles because they are permeable to the humidity. The pellets presented mean size of 1.10 mm, satisfactory shape and yield (78.7 %), good dissolution in water (89.44 to 100.05 %) and good recovery (> 95 %) of the total polyphenol content in comparison with dry extract, the pellets were stable against UVC radiation when conditioned in amber glass bottles, however, the total polyphenol content was reduced when the samples were conditioned in open-dishes or in transparent glass bottles. In the accelerated stability testing, the pellets demonstrated to be hygroscopic and sensible to the heat. This effect was more pronounced when the samples were conditioned in permeable flasks (polyethylene ethyl bottles) than in semi-permeable flasks (transparent glass bottles). These findings point to the relevance of reducing the residual moisture of both dry extract and pellets, as well as to the necessity of conditioning both into opaque humidity tight packing, at low temperatures.

Este trabalho apresenta e consolida uma metodologia alternativa para a determinação de taxas de reação nuclear ao longo da direção radial das pastilhas combustíveis sem necessidade de intensos fluxos neutrônicos. Esta técnica se baseia na irradiação de um disco de UO2 inserido no interior de uma vareta combustível desmontável no núcleo do reator IPEN/MB-01. Após a irradiação são realizadas várias espectrometrias gama do disco utilizando um detector HPGe alternando sequencialmente 6 colimadores de chumbo com diâmetros diferentes. Consequentemente, as reações nucleares de captura radiativa que ocorrem nos átomos de 238U, juntamente com as fissões que ocorrem em ambos 235U e 238U são mensuradas em função de 6 regiões radiais distintas do disco combustível. As correções de eficiência geométrica devido à introdução dos colimadores no sistema de detecção HPGe são determinadas através do código MCNP-5. As medidas de taxa de fissão são realizadas utilizando o 99Mo como radionuclídeo traçador. Esse radionuclídeo foi estudado e provou-se ideal para estas medidas por possuir um comportamento linear de formação, alto rendimento de fissão e principalmente por emitir fótons de baixa energia. As medidas foram efetuadas irradiando discos de UO2 (com enriquecimento de 4,3%) na posição central do reator IPEN/MB-01 a potência de 100 Watts durante uma hora. Algumas medidas foram realizadas utilizando uma luva de cádmio envolta na vareta combustível para determinar as taxas de reação nuclear na faixa de energia epitérmica. Os resultados experimentais obtidos são comparados a cálculos de taxa de reação nuclear via MCNP-5 utilizando a biblioteca de dados ENDF/B-VII.0, os quais apresentaram discrepâncias de no máximo 9% para as taxas de captura no 238U e 14% para as taxas de fissão no U na faixa epitérmica. Foram obtidos valores máximos de 4,5% para incertezas relativas as taxas de captura total e epitérmica e para as taxas de fissão total e epitérmica valores máximos de 11,3%. / This research presents and consolidates an alternative methodology for determining nuclear reaction rates along the radial direction of the fuel pellets which does not require high neutron flux. This technique is based on irradiating a thin UO2 disk inserted into a removable fuel rod at the IPEN/MB-01 reactor core. Several gamma spectrometries are performed after irradiation using a HPGe detector. Six lead collimators with different diameters are sequentially alternated during this process, thus, the nuclear radioactive capture which occurs in 238U and the fissions which occur in both 235U and 238U are measured according to six different radial regions of the fuel disk. Geometric efficiency corrections due to the introduction of collimators in HPGe detection system are determined by MCNP-5 code. The fission rate measurements are performed using the 99Mo. This radionuclide was studied and proved ideal for these measurements because it is formed in linear behavior in the reactor core, have a high yield fission and emits low-energy photons. Measurements were performed irradiating UO2 disks (with 4.3% enrichment) in the central position of the IPEN/MB-01 core at 100 watts power level during one hour. Some measurements were performed using a cadmium glove wrapped in the fuel rod to determine the nuclear reaction rates in the epithermal energy range. The experimental results obtained are compared with nuclear reaction rate calculations by means of MCNP-5 with ENDF/B-VII.0 data library showing discrepancies of up to 9% in 238U capture rates and 14% for U fission rates for epithermal energies. Uncertainties regarding the nuclear capture rates have maximum values of 4.5% and the fission rates has maximum values of 11.3%.

Dans le domaine spatial, la contamination moléculaire est un problème important pouvant affecter considérablement la performance des instruments embarqués. Selon l’environnement thermique, certaines molécules polluantes provenant du dégazage sous vide des matériaux constitutifs des satellites viennent en effet se déposer sur les surfaces sensibles telles que les optiques et les différents détecteurs. Grâce à leur structure microporeuse organisée qui leurs confère de remarquables capacités d’adsorption, les zéolithes sont des solides de choix pour minimiser les risques de pollution. Les pastilles, billes et peintures zéolithiques offrent plus précisément l’avantage d’être directement intégrées dans la structure interne des satellites, sont légères et non pulvérulentes. C’est pourquoi l’objectif de cette thèse est d’étudier la mise en forme de poudre zéolithique. Les propriétés mécaniques et les propriétés d’adsorption des objets obtenus seront étudiées pour confirmer leur utilisation dans le domaine du spatial.Au cours de ce travail, trois mises en forme ont été développées : les pastilles, les billes et les peintures zéolithiques. Les pastilles zéolithiques ont présenté des propriétés mécaniques très intéressantes, contrairement aux billes zéolithiques qui peuvent engendrer une contamination particulaire lors de la mise en orbite du satellite (vibrations). Les capacités d’adsorption de ces deux mises en forme sont satisfaisantes : des molécules telles que le n-hexane, le cyclohexane et le 3-méthylpentane y ont été adsorbées. Enfin, la première formulation de peinture zéolithique a conduit à des capacités d’adsorption correctes (diminution de 20 % due à la présence de liant) avec une adhésion (test ISO 2409) acceptable. Cette dernière mise en forme est une des nombreuses perspectives des travaux réalisés au cours de cette thèse. / In low earth orbit, global performances of satellites can be affected by the contamination of critical surfaces as optical devices and detectors. On-orbit molecular contamination is due to outgassed organic pollutants emanating from spacecraft materials. One way to reduce and to eliminate this phenomenon is the use of molecular adsorbents. Among them, zeolites appear to be relevant materials for contaminants retaining. Unlike common powder materials, zeolites films can also avoid the secondary dust contamination due to particles breeding and can be easily inserted in the satellite structure. As a consequence, this work deals with the shaping of zeolitic powder.Three shapes were developed during this work: pellets, beads and paints. Zeolitic pellets showed very interesting mechanical properties, on the contrary to zeolitic beads which can beget a particulate contamination (vibrations). The adsorption capacities of these two shapes are good: molecules such as n-hexane, cyclohexane and 3-methylpentane were adsorbed. Finally, the first formulation of a zeolitic paint was developed: a loss of 20 % of the adsorption capacities was observed (presence of binder). The adhesion (ISO 2409 test) was acceptable. This last shape is one of the many perspectives of this work.

Natriumpicosulfat-Tropfen erlauben eine sehr genaue Dosierung. Die randomisierte, plazebokontrollierte, doppelblinde cross-over Studie mit 20 gesunden Probanden wurde durchgeführt, um weitere Informationen sowohl über eine Dosis-Wirkungsbeziehung als auch über dosisabhängige pharmakokinetische Parameter und Verträglichkeit zu erhalten. Das Ziel war die Messung der Kolontransitzeit und der Zeit bis zum Wirkungseintritt und der Überprüfung, ob es eine Beziehung zwischen den kinetischen und dynamischen Parametern gibt. Die Probanden nahmen jeweils 5, 10 oder 15 mg Natriumpicosulfat-Tropfen oder Plazebo in einer oralen Einmaldosis. Die Kolontransitzeit, die Zeit bis zum Wirkungseintritt, die Urinausscheidung von BHPM (aktiver Metabolit von Natriumpicosulfat) und die Verträglichkeit wurden untersucht. Die mittlere Kolontransitzeit und die mittlere Zeit bis zum Wirkungseintritt waren nach Einnahme von 5, 10 und 15 mg Natriumpicosulfat-Tropfen im Vergleich zu Plazebo signifikant verkürzt. Es konnte jedoch keine eindeutige Dosis-Wirkungsbeziehung gefunden werden. Die Ausscheidung von BHPM sinkt mit Erhöhung der Natriumpicosulfatdosis und einer beschleunigten Kolontransitzeit. Die Verträglichkeit war gut. Die Nebenwirkungen (Magenkrämpfe, Blähungen) sind das Resultat der motilitätswirksamen Eigenschaften von Natriumpicosulfat. / Sodium picosulfate drops allow a very accurate dosage. The randomized, placebo-controlled, double blind cross-over study in 20 healthy volunteers was to provide further information about a dose-response ratio as well as dose-dependent pharmacokinetic parameters and tolerance. The aim was to measure transit time and time to onset of action and to check whether there was a correlation between kinetic and dynamic data. The volunteers received 5, 10 and 15 mg sodium picosulfate drops or placebo orally in a single dose. Colon transit time, time to onset of defecation, urinary excretion of BHPM (the active principle of sodium picosulfate) and tolerability were tested. Mean transit time and mean time to onset were significantly reduced by 5, 10 and 15 mg of sodium picosulfate, compared to placebo. No clear dose-response ratio could be found. The urinary excretion of BHPM dropped with increase of administered dose and accelerated transit velocity. The tolerance was good. The adverse events (stomach cramps, flatulence) are the result of motility stimulating effect of sodium picosulfate.

<p>Biomass is considered to be a sustainable energy source with significant potentials for replacing electricity and fossil fuels, not at least in the residential sector. However, present wood combustion is a major source of ambient concentrations of hydrocarbons (e.g. VOC and PAH) and particulate matter (PM) and exposure to these pollutants have been associated with adverse health effects. Increased focus on combustion related particulate emissions has been seen concerning the formation, characteristics and implications to human health. Upgraded biomass fuels (e.g. pellets) provide possibilities of more controlled and optimized combustion with less emission of products of incomplete combustion (PIC´s). For air quality and health impact assessments, regulatory standards and evaluations concerning residential biomass combustion, there is still a need for detailed emission characterization and quantification when using different fuels and combustion techniques.</p><p>This thesis summarizes the results from seven different papers. The overall objective was to carefully and systematically study the emissions from residential biomass combustion with respect to: i) experimental characterization and quantification, ii) influences of fuel, appliance and operational variables and iii) aspects of ash and trace element transformations and aerosol formation. Special concern in the work was on sampling, quantification and characterization of particulate emissions using different appliances, fuels and operating procedures.</p><p>An initial review of health effects showed epidemiological evidence of potential adverse effect from wood smoke exposure. A robust whole flow dilution sampling set-up for residential biomass appliances was then designed, constructed and evaluated, and subsequently used in the following emission studies. Extensive quantifications and characterizations of particulate and gases emissions were performed for residential wood and pellet appliances. Emission factor ranges for different stoves were determined with variations in fuel, appliance and operational properties. The emissions of PIC´s as well as PM_tot from wood combustion were in general shown to be considerably higher compared to pellets combustion. PAH_tot emissions were determined in the range of 1300-220000 µg/MJ for wood stoves and 2-300 µg/MJ for pellet stoves with phenantrene, fluoranthene and pyrene generally found as major PAH´s. The PM emissions from present residential appliances was found to consist of significant but varying fractions of PIC´s, with emissions in the range 35-350 mg/MJ for wood stoves compared to 15-45 mg/MJ for pellet stoves. Accordingly, the use of up-graded biomass fuels, combusted under continuous and controlled conditions give advantageous combustion conditions compared to traditional batch wise firing of wood logs. The importance of high temperature in well mixed isothermal conditions was further illustrated during pellets combustion to obtain complete combustion with almost a total depletion of PIC´s. Fine (100-300 nm) particles dominated in all studied cases the PM with 80-95% as PM1. Beside varying fractions of carbonaceous material, the fine PM consisted of inorganic volatilized ash elements, mainly found as KCl, K₃Na(SO₄)₂ and K₂SO₄ with mass concentrations at 15-20 mg/MJ during complete combustion. The importance of the behavior of alkali elements for the ash transformation and fine particle formation processes was further shown, since the stability, distributions and compositions also directly control the degree of volatilization. In addition to the alkali metals, zinc was found as an important element in fine particles from residential biomass combustion. Finally, the behaviour of volatile trace elements, e.g. Zn and Cd, during pellets production and combustion were studied. A significant enrichment in the pellet fuel during the drying process was determined. The magnitude and importance of the enrichment was, however, relative small and some alternative measures for prevention were also suggested.</p>