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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

PAU vázané na velikostně segregovaný aerosol v městském ovzduší. / Aerosol size distribution of PAH in urban atmosphere

Bendl, Jan January 2014 (has links)
The aim of the study was to determine the 13 health risk PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene, ideno(1,2,3-cd)perylene and coronene; c-PAU highlighted) in the fractions of size-segregated aerosol of the urban air in Ostrava (2012, 2014) and Mlada Boleslav (2013) at low temperatures in winter, and to verify experimentally a sampling artifact, i.e., to quantify PAHs in the gas phase. For the particle size separation high-volume cascade impactor Hi-Vol BGI 900 was used. PAHs were determined by HPLC-FLD/PDA. In Ostrava in 2012 during the winter inversion (up to -25 řC), mean concentration of 13 PAHs in aerosol was 432 ng.m-3 ; in fraction 10 - 1 µm 119 ng.m-3 , 1 - 0,5 µm 185 ng.m-3 , 0,5 - 0,17 µm 91 ng.m-3 , in fraction < 0,17 µm 37 ng.m-3 and in the gaseous phase of min. 40 ng.m-3 . In the most unfavorable day 2. 2. 2012 (-18.6 ř C) reached the 24-hour average of 13 PAHs 890 ng.m-3 , the sum of carcinogenic PAHs 237 ng.m-3 and benzo(a)pyrene 32.3 ng.m-3 . An irregular and different decline of PAHs concentrations after inversion was measured: in fraction 1 - 10 µm 2.8 times, 0.5 - 1 µm 4.2 times, 0.5 - 0.17 µm 4 times and for <0.17 µm up to 7.6 times....
202

Détermination expérimentale de la distribution de taille de pores d’un milieu poreux par l’injection d’un fluide à seuil ou analyse harmonique / Experimental identification of the pore size distribution of porous media using a frequency analysis or a yield stress fluid.

Malvault, Guillaume 27 September 2013 (has links)
Deux approches pour caractériser les milieux poreux en terme de distribution de taille de pores (DTP) sont développées au sein de l'équipe ECPS. Ce travail a pour but de confirmer expérimentalement leurs validités. A l'instar des autres méthodes utilisant l'intrusion du mercure, l'adsorption isotherme ou la thermoporosimétrie, la première méthode consiste à utiliser un fluide à seuil d'écoulement. En effet, l'utilisation de l'écoulement d'un fluide à seuil de type Herschel-Bulkley, au travers d'un poreux, en fonction du gradient de pression permet (en utilisant les solutions analytique et numérique du problème inverse) de déterminer la fonction de distribution de la taille de pores. La seconde méthode utilise l'admittance complexe d'un milieu poreux, mesurée à partir de la réponse en débit à une sollicitation harmonique du gradient de pression. Comme la fréquence de la sollicitation est reliée aux rayons des pores par le biais de la profondeur de pénétration hydrodynamique, l'admittance permet de retrouver la distribution de taille de pores par la résolution numérique du problème inverse associé. Ces deux techniques sont basées sur le modèle de faisceaux de capillaires parallèles employé dans la plupart des autres études qui traitent du même problème. Nos expériences s'appuient sur des milieux poreux calibrés. L'application de ces techniques aux milieux poreux réels se fait actuellement en collaboration avec le TREFLE de Bordeaux. Les résultats expérimentaux obtenus affirment clairement la validité et l'applicabilité de ces deux méthodes pour la caractérisation de la DTP. Il est désormais envisageable de les transférer pour un usage industriel. / Two approaches to characterize porous media in terms of pore size distribution (PSD) are developed within our ECPS team. The aim of this study is to experimentally confirm their validity. Like the other methods using mercury intrusion, adsorption isotherm or thermoporometry, the first method consists in the use of a fluid flow threshold. Indeed, the use of flow of a yield-stress fluid like those of Herschel-Bulkley's, through a porous media, versus the pressure gradient, permits (using the analytical and numerical solutions of the inverse problem) to determine the distribution function of its PSD. The second method uses the complex admittance of a porous medium, measured from the flow rate response to a harmonic pressure gradient. As the frequency of the sollicitation is related to the pore radius through the hydrodynamic penetration depth, the admittance allows to determine the PSD using numerical solution of the associated inverse problem. Both techniques are based on the parallel capillaries bundle model, as used in most of similar studies. Our experiments use calibrated porous media. The application of these techniques to real porous media is currently lead in collaboration with the TREFLE (Bordeaux). Our experimental results clearly confirm the validity and the applicability of these methods for the characterization of the PSD. It is now possible to transfer them for an industrial use.
203

Flow experiments of yield stress fluids in porous media as a new porosimetry method / Expériences d'écoulement de fluides à seuil en milieu poreux comme nouvelle méthode de porosimétrie

Rodriguez de Castro, Antonio 17 July 2014 (has links)
Les méthodes expérimentales utilisées actuellement pour déterminer la distribution de taille des pores (DTP) dans les milieux poreux présentent des inconvénients, tels que par exemple, la toxicité des fluides employés (porosimétrie à mercure). La base théoriques d'une nouvelle méthode pour obtenir la DTP a été proposée dans la littérature. Celle-ci est fondée sur l'injection de fluides à seuil, caractérisés par une contrainte de cisaillement en deçà de laquelle ils ne s'écoulent pas. L'idée principale de ces travaux théoriques est que l'écoulement de fluides à seuil à travers un milieu poreux permet d'obtenir sa DTP à partir de la mesure des débits correspondant à différents gradients de pression Q(∇P). L'objectif du travail proposé ici est de présenter une nouvelle méthode d'exploitation des données expérimentales Q(∇P) permettant d'obtenir de façon simple, robuste et reproductible les DTPs des milieux poreux analysés. La démarche consiste à évaluer la contribution au débit total des nouveaux pores qui s'incorporent à l'écoulement entre deux valeurs de ∇P. Ces nouveaux pores sont caractérisés par un rayon représentatif qui est fonction de la contrainte seuil du fluide et de ∇P. L'importance de leur contribution au débit total par rapport à celle d'un seul pore donne le nombre de pores dans l'échantillon ayant ce rayon représentatif. Cette méthode est d'abord testée et validée avec des expériences générées numériquement. Ensuite, elle est utilisée pour exploiter des données provenant d'expériences de laboratoire réalisées avec de différents milieux poreux. Les résultats obtenus en termes de DTPs sont comparés avec ceux fournis par d'autres techniques: porosimétrie à mercure et microtomographie. / Current experimental methods used to determine pore size distributions (PSD)of porous media present several drawbacks such as toxicity of the employed fluids (e.g., mercury porosimetry). The theoretical basis of a new method to obtain the PSD by injecting yield stress fluids through porous media and measuring the flow rate Q at several pressure gradients ∇P was proposed in the literature. On the basis of these theoretical considerations,an intuitive approach to obtain PSD from Q(∇P) is presented in this work. It relies on considering the extra increment of Q when ∇P is increased, as a consequence of the pores of smaller radius newly incorporated to the flow. This procedure is first tested and validated on numerically generated experiments. Then, it is applied to exploit data coming from laboratory experiments and the obtained PSDs are compared to those deduced by mercury porosimetry and micro tomography.
204

Geometry and stratigraphy of the Limeira tholeiitic intrusion, Paraná¡ magmatic province (SP-Brazil) / Geometria e estratigrafia da intrusão de Limeira (SP-Brasil)

Santos, Lucas Martins A. dos 23 November 2018 (has links)
The Limeira Intrusion is an occurrence related to the Mesozoic continental flood basalts of Paraná Magmatic Province, cropping out at the eastern São Paulo state. It is made up of basic- intermediate rocks with a great diversity of structures, textures, and modal compositions, related to the specific evolutionary process in a magma chamber. 2D forward modeling of magnetometric data, based on available aerial and newly obtained ground data integrated with in situ rock magnetic susceptibility measurements, were used to establish its geometry. The results, even considering intrinsic drawbacks of magnetometric theoretical models, are compatible with the geologic-based presumed intrusion geometry. In addition, the stratigraphic analysis of compositional and textural variations, coupled with the structural and geometric features, allowed the interpretation of its emplacement mechanism and thermal evolution. Quantitative textural analysis through crystal size distribution (CSD) of plagioclase crystals, the spatial distribution pattern of structures, microtextures, granulation, and rock-types, evidenced the internal heterogeneities of this occurrence. An approximately 110 m top-to-floor exposure section reveals that its internal heterogeneity was caused by non-instantaneous successive emplacement of three different magma injections. The textural analysis also reveals fine-grained crystals formed under different cooling paths, present in medium- to coarse- grained rocks within the intrusion, next to sharp contacts between different rock compositions. The contacts between different rocks are characterized by hybridization textures and by significant amounts of plumose granophyre-type and plumose plagioclase. The time lapse between consecutive pulses is responsible for a stepwise cooling-path, preservation of hybridization textures, and the development of almost rigid surfaces providing crystals alignment during magma flow. High-resolution Sr-isotopy data demonstrates a complex assembly history, possibly involving filter pressing of residual liquids, and pre-existent crystals before magma installation in coarse-grained rocks. It is also possible to recognize fewer amounts of country-rocks assimilation, which decreases towards the intrusion\'s core and can be associated with magma migration due to filter pressing processes. In the feeder zone, the evolution of emplacement was marked by an almost continuous decrease in wall-rock assimilation by the consecutive magma batches. / A intrusão de Limeira é uma ocorrência associada aos basaltos continentais Mesozoicos da Província Magmática do Paraná, aflorando na região leste do estado de São Paulo. Esta intrusão é composta por rochas básico-intermediárias que ocorrem com grande diversidade de estruturas, texturas e composições modais, relacionados aos mecanismos evolutivos específicos desta câmara. A modelagem magnetométrica bidimensional, baseado em aerolevantamentos disponíveis e dados recentes obtidos em campo e integrados às medidas de suscetibilidade magnética em rocha, foram utilizados para estabelecer sua geometria. Os resultados, mesmo considerando as desvantagens intrínsecas teóricas do método, são compatíveis com o modelo geológico presumido para esta intrusão. Adicionalmente, a análise das variações estratigráficas de composição e texturas, associados aos parâmetros estruturais e geológicos, permitiram a interpretação dos mecanismos de colocação e evolução térmica desta intrusão. Análises texturais quantitativas através da análise de distribuição de tamanho de cristais (DTC), a distribuição espacial de padrões estruturais, microtexturas, granulação e litotipos, evidenciam a heterogeneidade interna desta ocorrência. A seção de aproximadamente 110 metros de topo- a-base revela que sua heterogeneidade interna foi causada pela injeção sucessiva de pelo menos três pulsos magmáticos. Através da análise textural foram reconhecidos cristais de plagioclásio de granulação muito fina a fina presentes em rochas de granulação média a grossa, formados em diferentes razões de resfriamento e próximo ao contato abrupto entre rochas de diferentes composições. Estes contatos caracterizam zonas onde são reconhecidas texturas híbridas e são marcados pela presença e abundância de intercrescimentos granofíricos do tipo plumoso e plagioclásios plumosos. O espaço de tempo entre pulsos magmáticos consecutivos é responsável pela evolução térmica em etapas nesta intrusão, preservando as texturas de hibridização, e desenvolvendo superfícies com rigidez suficiente para promover o alinhamento de cristais de plagioclásio por fluxo magmático. Análises isotópicas demonstram um processo de colocação complexo para este corpo, possivelmente envolvendo a filtragem por pressão dos líquidos residuais da cristalização dos pulsos iniciais, além da existência de ante-cristais formados antes da instalação das rochas de granulação grossa. Também é possível reconhecer o processo de assimilação de uma pequena parcela das rochas encaixantes, principalmente pelas rochas das bordas, que decai para o centro da intrusão e é marcado pela migração dos líquidos residuais. Na zona de alimentação, a evolução da colocação é marcada pela diminuição do processo de assimilação pelos pulsos seguintes.
205

Distribuição do tamanho de cristais (DTC) e trama de plagioclásio em diques máficos Mesozóicos das Praias das Conchas e de Lagoinha (Municípios de Cabo Frio e Arraial de Búzios, RJ) / Crystal size distribution (CSD) and plagioclase fabrics in Mesozoic mafic dykes of the Beaches of Conchas and Lagoinha, (Municipalities of Cabo Frio and Armação dos Búzios, RJ)

Ngonge, Emmanuel Donald 28 April 2011 (has links)
A técnica da Distribuição do Tamanho de Cristais - DTC (Crystal Size Distribution - CSD), que relaciona a densidade de cristais com a distribuição do tamanho, foi aplicada à população de plagioclásio de diques máficos do Enxame de Cabo Frio - Búzios (RJ). Os diques possuem larguras variáveis, de alguns centímetros a 20 metros, e orientação em torno de N45E. A textura dos diques é geralmente fina, localmente microporfirítica e intergranular no centro dos diques mais largos. Bordas resfriadas de alguns centímetros de largura são frequentes nos contatos com as rochas metamórficas encaixantes. Foram estudados dois diques na Praia das Conchas com espessura de 0,8m e 8,2m e, um outro na Praia da Lagoinha, com 2m de largura. As amostras foram coletadas junto às margens (~10 cm do contato) e no centro dos diques. O tamanho médio dos cristais de plagioclásio varia de 0,07 a 0,13 mm na borda dos diques mais finos (<= 2 m de largura) e de 0,09 a 0,20 mm na borda do dique mais largo. No centro do dique de Lagoinha e no dique largo de Praia das Conchas o tamanho de plagioclásio é da ordem de 0,19 ± 0,02 mm e 0,60 ± 0,07 mm, respectivamente. As DTCs nas bordas dos diques, independentemente de sua largura, mostraram um padrão tipicamente encurvado, e que tem sido atribuído na literatura como evidência para misturas de magmas com populações de cristais de tamanhos distintos. No entanto, no centro do dique largo (8,2m) de Praia das Conchas, a DTC é log-linear consistente com uma cristalização magmática simples. A química mineral mostrou que os cristais maiores (precoces) de plagioclásio apresentam um teor mais elevado em An (bytownita-labradorita) que os cristais menores (tardios) da matriz (labradorita-andesina). Além disso, a olivina é mais rica em Fo na borda que no centro do dique e, respectivamente, o piroxênio mais enriquecido em Ca. Esses resultados indicam que as margens resfriadas são mais máficas que o centro sugerindo uma evolução química normal com o resfriamento do magma. Portanto, as DTCs encurvadas provavelmente refletem taxas de cristalização heterogêneas possivelmente induzidas pela despressurização durante a ascensão do magma basáltico seguida de rápido resfriamento. O padrão da DTC log-linear no centro do dique de 8,2m de largura é atribuído ao maior tempo de residência do magma que favoreceria os processos de difusão química e re-equilíbrio textural. Os cálculos da taxa de resfriamento utilizando a inclinação da DTC permitiram estimar que o centro do dique largo da Praia das Conchas estaria completamente cristalizado (~ 900 °C) em torno de 73 dias. O estudo da Orientação Preferencial de Forma (OPF) de plagioclásio mostrou que a petrotrama tende a isotrópica nas margens dos diques com largura menor que 2 metros, o que poderia refletir uma rápida cristalização de plagioclásio por despressurização. Quando a trama é localmente definida, como no dique largo da Praia das Conchas, a lineação de plagioclásio é subhorizontal sugerindo que o fluxo magmático moveu-se predominantemente na lateral do dique. / The method of Crystal Size Distribution (CSD), which relates crystal density with size distribution, has been applied on the plagioclase population of the Mafic Dyke Swarm of Cabo Frio-Búzios (RJ). The dykes are NE-trending with widths from a few centimetres to 20m. The texture is generally fine grained and locally microporphyritic and intergranular at the center of the larger dykes. Chilled margins of a few centimetres in width are common at contacts with the metamorphic basement. Two dykes of 0.8m and 8.2m in width of the Conchas Beach and another of 2m in width at the Lagoinha Beach have been studied. Samples were collected at the margins (~10cm from the contact) and at the center of the dykes. The average characteristic size of the plagioclase crystals varies from 0.07 to 0.13mm at the margins of the narrow dykes (<=2m of width) and from 0.09 to 0.20mm at the margins of the large dyke. At the center of the Lagoinha and Conchas dykes the plagioclase size varies from 0.19 ±0.02mm and 0.60±0.07mm respectively. The CSDs at the dyke margins, irrespective of the dyke width, are typically concave-up, and in literature such patterns have been attributed as evidence of magma mixing with distinct crystal populations. However, at the center of the largest dyke (8.2m) of Conchas Beach, the CSD is log-linear, consistent with simple steady-state crystallization pattern. The mineral chemistry shows that the plagioclase phenocrysts have a high An content (bytownite-labradorite) than the groundmass grains (labradorite-andesine). At the margins olivine is richer in Fo than at the center, and respectively, pyroxene is richer in Ca. These results indicate that the chilled margin is more mafic than the center suggesting a normal chemical evolution in a cooling magma. Nevertheless, the concave-up CSDs probably depict heterogeneous crystallization rates possibly induced by depressurization during the ascent of the basaltic magma followed by rapid cooling. The log-linear CSD pattern at the center of the Conchas dyke (8.2m width) is attributed to a higher residence time of the magma which favors the processes of chemical diffusion and textural re-equilibration. The calculated cooling rates using the CSD slope enables us to estimate that the larger dyke of Conchas would be completely crystallized (at ~900oC) in 73 days. The study of the Shape Preferred Orientation (SPO) in plagioclase shows an isotropic petrofabric at the margins of the dykes <=2m, which could reflect a rapid crystallization of plagioclase by depressurization. When the fabric is defined, as in the larger Conchas Beach dyke, the plagioclase lineation is subhorizontal, suggesting that the magma flow was predominantly lateral to the dyke plane.
206

Produção e caracterização de celulose cristalina e amorfa e de partículas de quitosana para aplicação como estabilizantes de emulsões óleo-em-água / Production and characterization of crystalline and amorphous cellulose and chitosan particles for application as stabilizers of oil-in-water emulsions

Bertan, David Willian 24 July 2018 (has links)
Emulsões são sistemas formados quando dois componentes imiscíveis são misturados, na forma de gotículas dispersas numa fase contínua, estabilizados pela ação de emulsificantes, compostos anfifílicos, com afinidades por ambas as fases do sistema. No caso de emulsões de Pickering, o sistema é estabilizado por partículas coloidais sólidas, que adsorvem à interface das gotículas da emulsão. O objetivo desta dissertação foi produzir e caracterizar suspensões de celulose cristalina (CC), celulose amorfa (CA) e de partículas de quitosana (PQ) e avaliar seu potencial de aplicação como únicos compostos estabilizantes em emulsões óleo-em-água. As CC e CA foram produzidas por tratamentos térmico e ácido de celulose microcristalina, respectivamente, enquanto que as PQs foram produzidas por tratamento ácido de quitosana de média massa molecular. Em todos esses casos, os tratamentos foram seguidos de ultra-agitação: 0 (ST), 10000 (UT10), 15000 (UT15) ou 20000 rpm (UT20) por 3 minutos. As suspensões de CC, CA e PQ foram caracterizadas para determinação da distribuição do tamanho de partículas, do potencial zeta e da estabilidade física, e por microscopia eletrônica de varredura e/ou de força atômica. As partículas em pó, produzidas por liofilização, foram submetidas a análises de difração de raios-X, espectroscopia de infravermelho com Transformada de Fourier (FTIR) e de colorimetria instrumental. Em função dessas caracterizações, foi estudado o efeito do tipo de partícula estabilizadora (CC, CA ou PQ) sobre o tamanho de gotas, colorimetria instrumental e estabilidade física de emulsões com 20% (v/v) de óleo de soja, sem e com &beta;-caroteno. Observou-se que os tratamentos UT10, UT15 e UT20 provocaram importantes alterações na distribuição de tamanho de partículas, com redução do tamanho médio das partículas, sem efeito significativo da velocidade de agitação. Em relação à PQ, os tratamentos por ultra-agitação não influenciaram o tamanho de partículas, nem quando comparado com suspensões ST. A CC apresentou-se em fragmentos de fibras celulósicas e altamente instáveis em suspensão, com índices de instabilidade próximos a 0,78. A CA apresentou-se em partículas coloidais e agregados irregulares, com estabilidade física razoável em suspensão (0,26). As suspensões de PQ apresentaram grandes estruturas cristalinas de acetato de sódio, junto a partículas coloidais de quitosana, mas altamente estáveis em suspensão aquosa (0,04). De forma geral, o potencial &zeta; e a estabilidade física das suspensões de CC, CA e PQ não variaram com o tratamento (ST, UT10, UT15 e UT20). Na caracterização das partículas liofilizadas, constatou-se alto índice de cristalinidade da CC (81%), e baixa cristalinidade da CA (42%) e da PQ (40%). Os tratamentos não provocaram modificações consideráveis na estrutura química, analisada por FTIR, e nem na cor instrumental da CC, CA e PQ. Por fim, apenas a PQ foi capaz de produzir e estabilizar emulsões óleo-em-água, não havendo formação de fase creme durante o armazenamento. A adição de 0,005% de &beta;-caroteno à fase lipídica deixou as emulsões estabilizadas por PQ ligeiramente alaranjadas e aumentou sua estabilidade física, sem afetar o tamanho médio de suas gotas (29-32 &micro;m). Portanto, apenas a PQ demonstrou potencial para estabilizar emulsões óleo-em-água, com ou sem &beta;-caroteno. / Emulsions are systems formed when two immiscible components are mixed, presenting dispersed droplets in a continuous phase, stabilized by emulsifiers, amphiphilic compounds, with affinities for both phases of the system. In the case of Pickering emulsions, the system is stabilized by solid colloidal particles, which adsorb at the interface of the emulsion droplets. The objective of this dissertation was to produce and characterize suspensions of crystalline cellulose (CC), amorphous cellulose (CA) and chitosan particles (PQ) and to evaluate its potential as single stabilizing compounds in oil-in-water emulsions. CC and CA were produced by heat and acidic treatments of microcrystalline cellulose, respectively, whereas PQs were produced by acidic treatment of medium molecular weight chitosan, also followed by ultra-stirring treatment. In all cases, the treatments were followed by ultra-stirring: 0 (ST); 10,000 (UT10); 15,000 (UT15) or 20,000 rpm (UT20) for 3 minutes. The suspensions of CC, CA and PQ were characterized for determination of particle size distribution, zeta potential and physical stability, and by scanning electron microscopy and/or atomic force microscopy. The powder particles, produced by freeze-drying, were subjected to analysis by X-ray diffraction, Fourier Transform infrared spectroscopy (FTIR) and instrumental colorimetry. As a function of these characterizations, the effect of the stabilizing particle type (CC, CA or PQ) on droplet size, instrumental colorimetry and physical stability of emulsions with 20% (v/v) soybean oil, without and with &beta;-carotene was studied. It was observed that the treatments UT10, UT15 and UT20 caused important changes in the particle size distribution, with reduction of the mean particle size, without significant effect of the agitation speed. Regarding chitosan particles, ultra-stirring treatments did not influence particle size, neither when compared to suspensions without pretreatment. CC was presented as highly unstable cellulosic fiber fragments in suspension, with instability indexes close to 0.78. CA was presented in colloidal particles and irregular aggregates, with reasonable physical stability in suspension (0.26). The suspensions of PQ showed large crystalline structures of sodium acetate, together with colloidal chitosan particles, but highly stable in aqueous suspension (0.04). In general, the potential &zeta; and the physical stability of CC, CA and PQ suspensions did not change with the treatment (ST, UT10, UT15 and UT20). In the characterization of the freezedried particles, a high crystallinity index of CC (81%) was observed, whereas CA (42%) and PQ (40%) showed low crystallinities. The treatments neither caused significant changes in the chemical structure, analyzed by FTIR, nor in the instrumental color of CC, CA and PQ. Finally, only PQ was able to produce and stabilize oil-in-water emulsions, with no cream phase formation during storage. Addition of 0.005% &beta;-carotene to the oil phase left the emulsions stabilized by PQ slightly orange and increased the physical stability of the emulsions, without affecting the droplet size of the emulsions (29-32 &micro;m). Therefore, only PQ demonstrated the potential to stabilize oil-in-water emulsions, with or without &beta;-carotene.
207

Métrologie de la fraction fine de l'aérosol métallurgique : apport des techniques micro-analytiques (microspectrométrie X et spectroscopie de perte d'énergie des électrons / Metrology of the fine fraction of the metallurgical aerosol : contribution of single-particle analyses (Micro-spectrometry and Electron Energy Loss Spectroscopy)

Marris, Hélène 19 October 2012 (has links)
Les poussières émises par l'industrie métallurgique concourent à la qualité de l'air des zones urbaines voisines. Ces particules, émises par des procédés à "haute température", sont susceptibles d'évoluer rapidement au sein des panaches. L'objectif de l'étude est de caractériser la phase particulaire sur un site d'émission métallurgique et de déterminer la nature et l'amplitude des transformations physico-chimiques subies par ces particules dans les premières minutes de leur émission. Des prélèvements d'aérosols ont été réalisés au sein des cheminées et dans l'environnement proche d'une usine métallurgique (production d'alliage de ferromanganèse), dont l'atelier d'agglomération est le principal émissaire. Le spectre granulométrique des particules dans l'environnement montre un enrichissement de nanoparticules (10-100nm) après survol des masses d'air au dessus du site industriel. Les rejets caractéristiques de l'usine (émission d'oxydes de fer et de manganèse, mais également d'aluminosilicates) se trouvent la plupart du temps sous forme d'agglomérats de composition chimique hétérogène et de structure morphologique complexe. Ces agglomérats semblent évoluer rapidement par adsorption de composés organiques volatils ou de suies. L'étude de la spéciation du Fe et du Mn au sein de ces particules indique qu'elles sont sujettes à des réactions d'oxydation via des mécanismes de conversion gaz/particules au sein même du procédé industriel, aboutissant notamment à une oxydation du fer inversement proportionnelle à la taille des particules. Par contre, aucune évolution significative du degré d'oxydation du Fe et du Mn n'a été observée dans l'environnement proche de l'émissaire. / Steelworks activities are important sources of fine particles which may affect air quality in urban areas close to plants. Those particles are emitted by "high-temperature" processes and could evolve very quickly in the plumes. The main objective of this study is to evaluate the nature and the amplitude of physico-chemical evolutions of those particles in the few minutes after the emission. Aerosol samplings were performed inside the chimneys and in the close environment of a FeMn alloys manufacturing plant where the sintering unit is the most important source of particles. The number size distributions in the close environment show a higher abundance of nanoparticles (10-100nm) inside the plume, by comparison with air masses upwind from the plant. The chemical analysis indicates that particles characteristic of the plant emissions (iron and manganese oxides but also aluminosilicates) are mostly constituted of agglomerates. These agglomerates combine various compounds inside a same particle in a complex structure. Moreover, they evolve rapidly (in a few minutes) after emission by mixing with organic compounds inside the plume. This evolution results from the adsorption of volatile organic compound or the agglomeration with soot particles. The study of iron and manganese speciation inside particles shows that they are prone to oxidation reactions via gas/particle conversion mechanisms during the industrial process, leading notably to a higher iron oxidation state for the smallest particles. However, no change of iron and manganese oxidation state was observed in the close environment of the plant.
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Quantitative Charakterisierung makroporöser Materialien mittels NMR-Mikroskopie

Butz, Markus 20 September 1999 (has links)
Poröse Materialien sind von großer Bedeutung in verschiedenen Anwendungsbereichen und sind weit verbreitet sowohl in natürlicher oder technischer Herkunft. Ihre Eigenschaften werden in hohem Maße von der Struktur des Porenraumes bestimmt, die durch quantitative Parameter wie Porosität oder Porengrößenverteilung beschrieben werden kann. Für die Untersuchung poröser Materialien stehen verschiedene indirekte Porosimetrieverfahren zur Verfügung, die jedoch bei sehr großen Poren in der Größenordnung oberhalb von 10 um nur eingeschränkt anwendbar sind. Aus diesem Grund war das Ziel dieser Arbeit die Entwicklung eines Verfahrens zur direkten Charakterisierung großporiger Werkstoffe. Dabei sollte die NMR- Mikroskopie zur dreidimensionalen Abbildung des Porensystems verwendet werden und mit einer anschließenden Bildverarbeitung quantitative Parameter wie die Porengrößenverteilung ermittelt werden. Für die experimentellen Untersuchungen wurden zwei unterschiedliche Filtermaterialien ausgewählt, die Porengrößen oberhalb von 10 µm aufwiesen. Für die NMR-mikroskopische Abbildung des Porenraumes wurden die Materialien mit unterschiedlichen Intrusionsflüssigkeiten gefüllt, wobei dest. Wasser, Octamethylcyclotetrasiloxan und Dimethylsulfoxid verwendet wurden. Die NMR-mikroskopische Abbildung des Porenraumes erfolgte anhand der Protonen der verwendeten Intrusionsflüssigkeit, wobei eine 3D-Spinechopulssequenz verwendet wurde. Die maximal erreichte räumliche Auflösung lag bei einer Größe der isotropen Voxel von ca. 12 um. Weiterhin wurde von ausgewählten Proben dreidimensionale Aufnahmen mit der Röntgencomputertomographie angefertigt, sowie für einige Proben Messungen mit der Quecksilberporosimetriemessungen durchgeführt. Für die Auswertung der NMR-Mikroskopieaufnahmen wurde auf der Basis der kommerziellen Softwarebibliothek HORUS ein eigenes Bildverarbeitungsprogramm entwickelt. Dieses Programm analysiert schichtweise den 3D-Bilddatenstatz und ermittelt daraus Porengrößenverteilungen und Porenkanäle senkrecht zur Bildebene. Die Ergebnisse der Bildverarbeitung der NMR-Mikroskopieaufnahmen zeigen für die Glasfilterproben gute Übereinstimmungen mit den Herstellerangaben zu den Materialien. Die für die unterschiedlichen Glasfiltersorten ermittelten Porengrößenverteilungen widerspiegeln sowohl in ihren absoluten Werten als auch im Verhältnis zueinander gut die nominellen Porenweiten der ausgewählten Materialien. Die mit der Quecksilberintrusion ermittelten Porengrößenverteilungen zeigen eine Beziehung zu den durch die Bildverarbeitung ermittelten minimalen Weiten der Porenkanäle. Für die untersuchten Polyethylensintermaterialien wurden Porengrößenverteilungen ermittelt, die von den Herstellerangaben abweichen. Untersuchungen mit Quecksilberintrusionsmessungen und Elektronenmikroskopieaufnahmen ergaben ähnliche Resultate und stützten dadurch die NMR-mikroskopisch ermittelten Ergebnisse. Im Rahmen der Arbeit konnte gezeigt werden, daß sich die NMR-Mikroskopie in Verbindung mit der digitalen Bildverarbeitung gut für die quantitative Charakterisierung großporiger nichtmetallischer Systeme eignet. Es wurden entsprechende Bildverarbeitungsroutinen entwickelt und die experimentellen Bedingungen hinsichtlich der Steigerung der räumlichen Auflösung optimiert. / Porous materials are of great importance for many application and are widespread as well in their natural as in their technical occurence. Their properties are determined to a high degree by the structure of the pore space, which can be described quantitativly with parameters like porosity or pore size distribution. There are a number of indirect porosimetry methods for porous materials, however most of them are less suitable for large pores in the range above 10 microns. For this reason it was the purpose of the undertaken investigations to develop a method for the direct characterization of materials with large pores. The intention was to use the nmr microscopy for the three-dimensional imaging of the pore system and to determine quantitative parameters like the pore size distribution with a suitable image processing algorithm. For the experimental investigations two different filter materials were selected, which had pore widths larger than 10 microns. For the nmr microscopy imaging of the pore space the materials were filled with different intrusion fluids using distilled water, octamethylcyclotetrasiloxane, and dimethylsulfoxide. For the nmr microscopy imaging of the pore space the protons of the intrusion fluid were selected, using a three-dimensional spin echo sequence. The highest spatial resolution in the nmr microscopy experiments was at a size of approximately 12 microns for an isotropic voxel. Furthermore for a selected range of glass filter samples three-dimensional images were acquired with X-ray tomography and a number of samples were investigated with mercury porosimetry. For the analysis of the nmr microscopy data an image processing algorithm was programmed basing on the commercial imaging software library HORUS. This program sequentially analyses the slices of the 3D imaging dataset and calculates pore size distributions and extracts pore channels perpendicular to the slice plane. The results of the image processing of the nmr microscopy data show a good agreement with the manufactures specification for the glass filter, regarding the absolute values for the calculated pore size distributions and the relative values for different glass filter materials. The pore size distributions which were determined with mercury porosimetry show a good agreement with the minimal pore channel widths as they were determined from the image processing of the nmr microscopy data. The calculated pore size distributions of the investigated polyethylene sinter materials differed from the manufacturers specification. Investigations with mercury intrusion experiments and electron microscopy images gave similar results thus supporting the results from the nmr microscopy experiments. Within the scope of this work it could be demonstrated, that nmr microscopy in connection with a digital image analysis is very suitable for the quantitative characterization of non-metallic systems with large pores. The necessary image processing algorithms have been developed and the experimental parameters have been optimised in order to maximise the spatial resolution of the nmr microscopy images.
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Geometry and stratigraphy of the Limeira tholeiitic intrusion, Paraná¡ magmatic province (SP-Brazil) / Geometria e estratigrafia da intrusão de Limeira (SP-Brasil)

Lucas Martins A. dos Santos 23 November 2018 (has links)
The Limeira Intrusion is an occurrence related to the Mesozoic continental flood basalts of Paraná Magmatic Province, cropping out at the eastern São Paulo state. It is made up of basic- intermediate rocks with a great diversity of structures, textures, and modal compositions, related to the specific evolutionary process in a magma chamber. 2D forward modeling of magnetometric data, based on available aerial and newly obtained ground data integrated with in situ rock magnetic susceptibility measurements, were used to establish its geometry. The results, even considering intrinsic drawbacks of magnetometric theoretical models, are compatible with the geologic-based presumed intrusion geometry. In addition, the stratigraphic analysis of compositional and textural variations, coupled with the structural and geometric features, allowed the interpretation of its emplacement mechanism and thermal evolution. Quantitative textural analysis through crystal size distribution (CSD) of plagioclase crystals, the spatial distribution pattern of structures, microtextures, granulation, and rock-types, evidenced the internal heterogeneities of this occurrence. An approximately 110 m top-to-floor exposure section reveals that its internal heterogeneity was caused by non-instantaneous successive emplacement of three different magma injections. The textural analysis also reveals fine-grained crystals formed under different cooling paths, present in medium- to coarse- grained rocks within the intrusion, next to sharp contacts between different rock compositions. The contacts between different rocks are characterized by hybridization textures and by significant amounts of plumose granophyre-type and plumose plagioclase. The time lapse between consecutive pulses is responsible for a stepwise cooling-path, preservation of hybridization textures, and the development of almost rigid surfaces providing crystals alignment during magma flow. High-resolution Sr-isotopy data demonstrates a complex assembly history, possibly involving filter pressing of residual liquids, and pre-existent crystals before magma installation in coarse-grained rocks. It is also possible to recognize fewer amounts of country-rocks assimilation, which decreases towards the intrusion\'s core and can be associated with magma migration due to filter pressing processes. In the feeder zone, the evolution of emplacement was marked by an almost continuous decrease in wall-rock assimilation by the consecutive magma batches. / A intrusão de Limeira é uma ocorrência associada aos basaltos continentais Mesozoicos da Província Magmática do Paraná, aflorando na região leste do estado de São Paulo. Esta intrusão é composta por rochas básico-intermediárias que ocorrem com grande diversidade de estruturas, texturas e composições modais, relacionados aos mecanismos evolutivos específicos desta câmara. A modelagem magnetométrica bidimensional, baseado em aerolevantamentos disponíveis e dados recentes obtidos em campo e integrados às medidas de suscetibilidade magnética em rocha, foram utilizados para estabelecer sua geometria. Os resultados, mesmo considerando as desvantagens intrínsecas teóricas do método, são compatíveis com o modelo geológico presumido para esta intrusão. Adicionalmente, a análise das variações estratigráficas de composição e texturas, associados aos parâmetros estruturais e geológicos, permitiram a interpretação dos mecanismos de colocação e evolução térmica desta intrusão. Análises texturais quantitativas através da análise de distribuição de tamanho de cristais (DTC), a distribuição espacial de padrões estruturais, microtexturas, granulação e litotipos, evidenciam a heterogeneidade interna desta ocorrência. A seção de aproximadamente 110 metros de topo- a-base revela que sua heterogeneidade interna foi causada pela injeção sucessiva de pelo menos três pulsos magmáticos. Através da análise textural foram reconhecidos cristais de plagioclásio de granulação muito fina a fina presentes em rochas de granulação média a grossa, formados em diferentes razões de resfriamento e próximo ao contato abrupto entre rochas de diferentes composições. Estes contatos caracterizam zonas onde são reconhecidas texturas híbridas e são marcados pela presença e abundância de intercrescimentos granofíricos do tipo plumoso e plagioclásios plumosos. O espaço de tempo entre pulsos magmáticos consecutivos é responsável pela evolução térmica em etapas nesta intrusão, preservando as texturas de hibridização, e desenvolvendo superfícies com rigidez suficiente para promover o alinhamento de cristais de plagioclásio por fluxo magmático. Análises isotópicas demonstram um processo de colocação complexo para este corpo, possivelmente envolvendo a filtragem por pressão dos líquidos residuais da cristalização dos pulsos iniciais, além da existência de ante-cristais formados antes da instalação das rochas de granulação grossa. Também é possível reconhecer o processo de assimilação de uma pequena parcela das rochas encaixantes, principalmente pelas rochas das bordas, que decai para o centro da intrusão e é marcado pela migração dos líquidos residuais. Na zona de alimentação, a evolução da colocação é marcada pela diminuição do processo de assimilação pelos pulsos seguintes.
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Desenvolvimento de nanoemulsões à base de óleo de maracujá (\'Passiflora edulis\') e óleo essencial de lavanda (\'Lavandula officinalis\') e avaliação da atividade antiinflamatória tópica / Development of nanoemulsions containing passion fruit seed oil (Passiflora edulis) and lavender essential oil (Lavandula officinalis) and evaluation of its topical anti-inflammatory activity.

Camargo, Maria Fernanda Pires de 12 May 2008 (has links)
A nanotecnologia é um fenômeno que se aplica a praticamente todos os setores da ciência, sendo que na área cosmética o elevado investimento neste campo tem reforçado a idéia de que produtos nanotecnológicos proporcionam vantagens reais aos consumidores. A crescente exigência do consumidor e os avanços no conhecimento sobre obtenção e estabilidade dos sistemas dispersos viabilizam o desenvolvimento de veículos diferenciados como, por exemplo, nanoemulsões, que além da inerente estabilidade, apresentam aspecto sensorial agradável, alta capacidade de espalhabilidade e hidratação, além de poderem facilitar a penetração de ativos. Existem dois métodos de obtenção de nanoemulsões: os que empregam baixa ou alta energia de emulsificação. O uso de óleos vegetais em produtos cosméticos tem sido intensamente valorizado, baseando-se no conceito de que são seguros e biocompatíveis. O óleo de maracujá é extensamente empregado em formulações cosméticas e o óleo essencial de lavanda é citado na literatura pelo efeito cicatrizante e antiinflamatório, dentre outros. Esta pesquisa teve como objetivo desenvolver nanoemulsões à base de óleo de maracujá e óleo essencial de lavanda nas concentrações de 1,0, 2,0 e 5,0%, a partir de método a frio de baixa energia de emulsificação, bem como avaliar a influência da adição de outros componentes e dos parâmetros relacionados ao método de obtenção na estabilidade e tamanho de glóbulos das nanoemulsões e posteriormente avaliar a atividade antiinflamatória tópica da emulsão contendo 5,0% do óleo essencial em camundongos sem pêlo. Os resultados demonstraram que a adição do óleo essencial de lavanda no sistema provocou redução no tamanho de glóbulos e aumento da estabilidade física e que o método de emulsificação a frio foi eficaz na formação de nanoemulsões estáveis. O valor de EHL, o par de tensoativos, a proporção entre as fases aquosa/ oleosa e tensoativa, bem como a adição de silicones e eletrólitos e a velocidade de agitação influenciam sobremaneira as características e a estabilidade das dispersões obtidas. No estudo de estabilidade acelerada, observou-se a alteração significativa dos valores de pH e condutividade elétrica, o que possivelmente é decorrente da hidrólise de compostos presentes no óleo essencial. Os valores de potencial zeta e tamanho de glóbulos não demonstraram alteração relevante em 30 dias de estabilidade acelerada. Na avaliação in vivo, a nanoemulsão adicionada de 5,0% do óleo essencial de lavanda apresentou resultados significativos quando comparado aos demais grupos, o que sugere boa perspectiva na utilização tópica do óleo essencial de lavanda, sendo este merecedor de estudos complementares para a elucidação dos mecanismos antiinflamatórios envolvidos, dos componentes fito-químicos responsáveis por esta ação e da concentração a ser utilizada. / Nanotechnology is a phenomenon that applies to mainly all sectors of science and in the cosmetics area the high investment in this field has strengthened the idea that nanotechnology products offer real advantages to consumers. The growing demand of consumers and the advances in knowledge about production and stability of dispersed systems enable the development of differentiated vehicles such as nanoemulsions, which besides the inherent stability, have pleasant sensory aspect, high spread ability and hydration power, in addition they can facilitate the penetration of actives. There are two methods of obtaining nanoemulsions: those that employ low or high energy of emulsification. The use of vegetable oils in cosmetics has been intensely valued, based on the concept that is safe and biocompatible. Passion fruit oil is widely used in cosmetic formulations and lavender essential oil is reported in the literature for healing and anti-inflammatory effects, among others. The aim of this study was to develop nanoemulsion based in passion fruit oil and lavender essential oil in the concentrations of 1.0, 2.0 and 5.0%, from low-energy method of emulsification, not employing heating, and evaluate the influence of the addition of other materials and parameters related to the production method in the system stability and droplets size of nanoemulsions and then evaluate the anti-inflammatory activity of topical nanoemulsion containing 5.0% of lavender essential oil in hairless mice. The results demonstrated that the addition of lavender essential oil in the system caused reduction in the droplets size and increasing in the physical stability and that the method of emulsification used was effective in the formation of stable nanoemulsions. The HLB value, the pair of surfactants, the ratio between aqueous/oily and surfactant phase, the addition of silicones and electrolytes and speed of agitation particularly affect the characteristics and stability of the obtained dispersions. In the accelerated stability tests, there was a significant change in the pH and electrical conductivity values, which is possibly resulting from the hydrolysis of compounds present in the essential oil. The values of zeta potential and droplets size showed no relevant change in 30 days of accelerated stability. In the in vivo evaluation, the nanoemulsion added of 5.0% of the lavender essential oil showed significant results when compared to the other groups, which suggests good perspective on topical use of this oil, which is worthy of further studies to the elucidation of the anti-inflammatory mechanisms involved, the phyto-chemical components responsible for this action and the concentration of use.

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