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Commercial ebullated bed hydroprocessors, such as the LC-Finer, are used for the production of synthetic crude oil by upgrading bitumen extracted from the Canadian oil sands. The objectives of this thesis were to experimentally determine bubble characteristics at industrially relevant operating conditions for the design and optimization of the reactor’s recycle pan, as well as to investigate the impact of a catalyst density distribution on the reactor’s fluidization behaviour. High gas holdups have been reported for this type of industrial unit. As a result, high gas holdup conditions were required to assess the commercial unit fluid dynamics. Industrial conditions for the bubble characteristics in the reactor freeboard were simulated in a high pressure gas-liquid bubble column operating at 6.5 MPa using nitrogen and a 0.5 wt.% aqueous ethanol solution. Local bubble characteristics, including gas holdups, bubble rise velocities, and chord lengths, were investigated under various operating conditions using a novel monofibre optical probe designed for high gas holdup and elevated pressure. High gas holdups were achieved (up to 60%) and relatively narrow chord length distributions were observed, where 90% of the bubbles diameters were 1.0 mm or less. The energy dissipated through the distributor plate was shown to have a significant impact on the initial bubble size generated and high gas holdups were also achieved at atmospheric pressure by varying the open-surface area of the distributor. As a result, the impact of catalyst density distribution on local fluidization behaviour was investigated at atmospheric pressure using the previously designed high energy dissipation gas-liquid distributor plate and a 0.5 wt.% aqueous ethanol solution. Fresh and spent hydroprocessing catalysts having relatively narrow and wide density distributions were compared. The introduction of gas greatly impacted the fluidized bed dynamic by rendering the bed-freeboard interface diffuse at low superficial liquid velocity. Bed interface fluctuations were significantly reduced at elevated liquid flow rate due to average bubble size reduction caused by high shearing through the gas-liquid distributor plate. Solid holdup was most affected by the density distribution where bed expansion/contraction was dependent of the liquid flow rate due to varying particle-bubble dynamics.

Thesis advisor: Paul Davidovits / Aerosol particles are an important component of the Earth-Atmosphere system because of their influence on the radiation budget both directly (through absorption and scattering) and indirectly (through cloud condensation nuclei (CCN) activity). The magnitude of the raditaive forcing attributed to the direct and indirect aerosol effects is highly uncertain, leading to large uncertainties in projections of global climate change. Real-time measurements of aerosol properties are a critical step toward constraining the uncertainties in current global climate modeling and understanding the influence that anthropogenic activities have on the climate. The objective of the work presented in this thesis is to gain a more complete understanding of the atmospheric transformations of aerosol particles and how such transformations influence the direct and indirect radiative effects of the particles. The work focuses on real-time measurements of aerosol particles made with the Aerodyne Aerosol Mass Spectrometer (AMS) developed in collaboration with the Boston College research group. A key feature of the work described is the development of a lightscattering module for the AMS. Here we present the first results obtained with the integrated light scattering – AMS system. The unique and powerful capabilities of this new instrument combination are demonstrated through laboratory experiments and field deployments. Results from two field studies are presented: (1) The Northeast Air Quality Study (NEAQS), in the summer of 2004, conducted at Chebogue Point, Nova Scotia and (2) The Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in and around Mexico City, Mexico in March of 2006. Both field studies were designed to study the transformations that occur within pollution plumes as they are transported throughout the atmosphere. During the NEAQS campaign, the pollution plume from the Northeastern United States was intercepted as it was transported towards Europe. In this study, particles were highly processed prior to sampling, with residence times of a few days in the atmosphere. The MILAGRO campaign focused on the evolution of the Mexico City plume as it was transported north. During this study, regional and locally emitted particles were measured with residence times varying from minutes to days in the atmosphere. In both studies, the light scattering – AMS system provided detailed information about the density and composition of single particles, leading to important insights into how atmospheric processing transforms the particle properties. In Mexico City, the light scattering-AMS system was used for the first time as a true single particle mass spectrometer and revealed specific details about the atmospheric processing of primary particles from combustion sources.To quantify the radiative effects of the particles on climate, the processing and ultimate fate of primary emissions (often containing black carbon or soot) must be understood. To provide a solid basis for the interpretation of the data obtained during the field studies, experiments were conducted with a well characterized soot generation-sampling system developed by the Boston College research group. The laboratory soot source was combined with the light scattering – AMS system and a Cloud Condensation Nuclei Counter (CCNC) to measure the change in cloud-forming activity of soot particles as they are processed in the atmosphere. Because of the importance of black carbon in the atmosphere, several instruments have been developed to measure black carbon. In July of 2008, an intercomparison study of 18 instruments was conducted in the Boston College laboratory, with soot particles produced and processed to mimic a wide range of atmospherically-relevant conditions. Transformations in the physical, chemical, and optical properties of soot particles were monitored with the combined suite of aerosol instrumentation. Results from the intercomparison study not only calibrated the different instruments used in the study, but also provided critical details about how atmospheric processing influences the radiative effects of primary combustion particles. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

abstract: A general continuum model for simulating the flow of ions in the salt baths that surround and fill excitable neurons is developed and presented. The ion densities and electric potential are computed using the drift-diffusion equations. In addition, a detailed model is given for handling the electrical dynamics on interior membrane boundaries, including a model for ion channels in the membranes that facilitate the transfer of ions in and out of cells. The model is applied to the triad synapse found in the outer plexiform layer of the retina in most species. Experimental evidence suggests the existence of a negative feedback pathway between horizontal cells and cone photoreceptors that modulates the flow of calcium ions into the synaptic terminals of cones. However, the underlying mechanism for this feedback is controversial and there are currently three competing hypotheses: the ephaptic hypothesis, the pH hypothesis and the GABA hypothesis. The goal of this work is to test some features of the ephaptic hypothesis using detailed simulations that employ rigorous numerical methods. The model is first applied in a simple rectangular geometry to demonstrate the effects of feedback for different extracellular gap widths. The model is then applied to a more complex and realistic geometry to demonstrate the existence of strictly electrical feedback, as predicted by the ephaptic hypothesis. Lastly, the effects of electrical feedback in regards to the behavior of the bipolar cell membrane potential is explored. Figures for the ion densities and electric potential are presented to verify key features of the model. The computed steady state IV curves for several cases are presented, which can be compared to experimental data. The results provide convincing evidence in favor of the ephaptic hypothesis since the existence of feedback that is strictly electrical in nature is shown, without any dependence on pH effects or chemical transmitters. / Dissertation/Thesis / Ph.D. Applied Mathematics 2013

Made available in DSpace on 2017-07-24T19:38:07Z (GMT). No. of bitstreams: 1 FABIOMALINOSKI.pdf: 1967487 bytes, checksum: a8c89b1d9584a90151895d2cdcb1b6d6 (MD5) Previous issue date: 2012-05-07 / This work presents the compilation and analysis of several analytical data obtained in the characterization of shale fine and lime schist, two abundant residuals in the Petrosix process. In order to ensure better representativeness of results, samples of lime schist extracted from complete vertical cuts of the layer were analyzed, and indirect analysis procedure was adopted for the shale fine residual, which basically consists of the characterization of samples obtained from complete vertical sections of superior and inferior shale layers in the Mine Rio das Pedras pit, within the Irati formation, in São Mateus do Sul PR. Analytical results obtained though Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) revealed that the lime schist layer presents mass predominance of the elements: Calcium, Silicon and Magnesium, and that this predominance, as indicated by the X-Ray Diffraction analysis (XRD), is due to the significant presence of Dolomite (CaMg(CO3)2) and Quartz (SiO2), and that the great reduction of mass after the Fixed Mineral Residue analysis is mainly related to CO2 elimination, in the dolomite thermal decomposition process. In the shale fine characterization, analytical results obtained through ICP-AES demonstrated that superior and inferior shale layers presented mass predominance of the elements silicon and iron, and this predominance, as indicated by the XRD is mainly due to the presence of Quartz (SiO2) and Pyrite (FeS2), and that the mass reduction after Fixed Mineral Residue analysis is related to the elimination of organic matter and the Pyrite thermal decomposition, with the former as the most relevant factor. Shale layers also presented Albite, Microcline and Muscovite, particle density similar values, crude oil with chromatographic profile of relative elevation in mass between the Heptane and Undecane peaks, uniform distribution between Dodecane and Octacosane peaks, decreasing distribution between the Nonacosane and C72 peaks, with normal spare paraffins in an unresolved complex organic mixture. These results indicate that the fine shale residue has a composition that oscillates between the narrow parameters of superior and inferior shale. / Neste trabalho apresentamos a compilação e a análise de diversos dados analíticos obtidos na caracterização do Finos de Xisto e do Calcário de Xisto, dois resíduos abundantes do processo Petrosix. Para garantir maior representatividade de resultados, analisam s amostras de Calcário de Xisto extraídas de cortes verticais completos da camada, e adotamos um procedimento de análise indireta para o resíduo denominado Finos de Xisto, que consiste basicamente na caracterização de amostras obtidas de secções verticais completas das camadas de Xisto Superior e Xisto Inferior das cavas da Mina Rio das Pedras, dentro da Formação Irati, na cidade de São Mateus do Sul – PR. Os resultados analíticos obtidos por Espectrometria de Emissão Atômica por Plasma Indutivamente Acoplado (EEA-PIA) demonstraram que a camada denominada Calcário de Xisto apresenta predomínio mássico dos elementos: Cálcio, Silício e Magnésio, que este predomínio, conforme indicado na análise de Difração de Raios X (DRX), deve-se a presença expressiva de Dolomita (CaMg(CO3)2) e Quartzo (SiO2), e que a grande redução de massa após a análise de Resíduos Minerais Fixos está relacionada principalmente a eliminação de CO2, no processo de decomposição térmica da Dolomita. Na caracterização do Finos de Xisto, os resultados analíticos obtidos por EEA-PIA demonstraram que as camadas de Xisto Superior e Xisto Inferior apresentam predomínio mássico dos elementos Silício e Ferro, que este predomínio, conforme indicado na análise de DRX, deve-se em grande parte a presença de Quartzo (SiO2) e Pirita (FeS2), que a redução de massa após a análise de Resíduos Minerais Fixos está relacionada a eliminação da matéria orgânica e a decomposição térmica da Pirita, sendo o primeiro fator muito mais relevante. As camadas de Xisto também apresentaram Albita, Microclínio e Muscovita, valores semelhantes de massa específica de partículas, óleo bruto com perfil cromatográfico de relativa elevação em massa entre os picos de Heptano e Undecano, distribuição uniforme entre os picos de Dodecano e Octacosano, distribuição decrescente entre os picos de Nonacosano e C72, com normais parafinas sobressalentes numa mistura orgânica complexa não resolvida. Estes resultados indicam que o resíduo Finos de Xisto tem composição oscilante entre os estreitos parâmetros do Xisto Superior e do Xisto Inferior.

The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix.

The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix.