A study has been made of the transport of noradrenaline into human red cells and resealed ghosts. In cells uptake appeared to obey the kinetics of simple diffusion, whilst in metabolically inert ghosts, uptake was identified as a low affinity high capacity saturable transport mechanism. Uptake was markedly temperature sensitive but not dependent upon cellular metabolism, consistent mth facilitated diffusion rather than active transport of noradrenaline. Non-competitive inhibition of uptake was achieved by a variety of structurally related compounds when present at either the inner or outer membrane surface. The ionic requirements for noradrenaline transport by red cells and ghosts have been examined. VJhen external sodium was replaced isosmotically by N-methyl-D-glucamine the apparent affinity for uptake by ghosts was modestly inhibited. Replacement of external sodium by potassium was ineffective, suggesting a requirement for both sodium and/or potassium. Specific sodium transport inhibitors were without effect and it was shown that the mechanism has no requirement for calcium or magnesium. Replacement of external chloride by either nitrate or methylsulphate stimulated red cell noradrenaline accumulation, but was ineffective in ghosts. It is suggested that anion substitution may act secondarily on transport by affecting binding and/or catecholamine metabolism. Noradrenaline uptake was inversely proportional to external hydrogen ion concentration, suggesting that lipophilic substrate is favoured for transport. It is concluded that noradrenaline transport does not occur via the "uptake 1" or "uptake 2" pathways characterised in other tissues. It has been shown that the slowly metabolised noradrenaline analogue, guanethidine, is accumulated by red cells. Guanethidine transport is saturable, sodium and chloride independent, and inhibition studies reveal separate routes of entry for this compound and noradrenaline. Noradrenaline has no effect upon red cell cation transport. Therefore, abnormalities reported in clinical disorders, such as essential hypertension, are not attributable to increased plasma noradrenaline concentration.

Doctor of Philosophy / Department of Chemistry / Daniel A. Higgins / This dissertation describes the application of fluorescence microscopy techniques to investigations of mass transport phenomena in self-assembled nanomaterials. The microscopic morphologies of the materials and the mass-transport dynamics of probe molecules dispersed within them were assessed with high temporal and spatial resolution by single molecule imaging and spectroscopic methods. Three distinct sets of experiments were performed in completing the work for this dissertation. In the first study, single molecule imaging was employed to explore the interactions and field-induced migration of double-stranded DNA (ds-DNA) molecules with nanostructured Pluronic F127 gels. While DNA interactions with nanostructured gels have been explored in the past, none had apparently looked at these interactions in gels comprising hexagonally ordered arrays of cylindrical micelles. Therefore, these studies focused on materials DNA dispersed in flow aligned hexagonal F127. DNA molecules were found to be strongly confined in the hexagonal mesophase structures from their elongation, alignment, and exclusively occurred electrophoretic migration in the direction parallel to the cylinder long axis. These observations will lead to a better understanding of macromolecular interactions with nanostructured gels like those now being investigated for use in drug delivery and chemical separations. In the second study, imaging-fluorescence correlation spectroscopy (imaging-FCS) was used to study the rate and mechanism of sulforhodamine B (SRB) dye within novel bolaamphiphile-based self-assembled nanotubes. These nanotubes were only recently developed and their mass transport properties remain largely unexplored. The nanotubes employed here are unique because they incorporate amine groups and glucose groups on their inner and outer surfaces, respectively. Wide-field fluorescence video microscopy was first applied to locate and image dye-doped nanotubes dispersed on a glass surface. Imaging-FCS was employed as it allows for the dynamics to be recorded simultaneously from a large sample region, thus the SRB mass transport within nanotubes can be spatially resolved. The coulombic interactions between cationic ammonium ions on the inner nanotube surface and the anionic SRB molecules was shown to play a critical role in governing dye dynamics under varied pH and ionic strength conditions. Mass transport of SRB within the nanotubes is concluded to occur by a desorption-mediated Fickian diffusion mechanism. In the third set of experiments, solvatochromic dye molecules were employed in novel imaging-FCS studies of the role played by partitioning in governing mass transport phenomena within the same organic nanotubes used above. Two forms of the solvatochromic dye Nile Red (NR) were employed: the commercial hydrophobic form of NR, and a more polar derivative 2-hydroxybenzophenoxazinone (named NR-OH). The partitioning of dye molecules within the nanotubes was investigated assessing the diffusion rate for each dye. The preliminary results suggested NR and NR-OH preferentially partitioned into the tube walls and the ethanol phase filling the tubes, respectively. The diffusion coefficient data indicated NR-OH diffused faster than NR, consistent with the presence of NR-OH in a relatively less viscous environment (e.g., the ethanol phase filling the tubes). The results of these studies afford information essential to the use of organic nanotubes in controlled drug release and possibly in catalysis applications.

Doctor of Philosophy / Department of Chemistry / Takashi Ito / This dissertation describes single-molecule tracking (SMT) measurements for the quantitative characterization of one-dimensional (1D) nanostructures in 200 nm-thick surfactant-templated mesoporous silica (STMS) and cylinder-forming polystyrene-poly(ethylene oxide) diblock copolymer (CF-PS-b-PEO) films with a μm-scale thickness. SMT is advantageous for the characterization of nanomaterials over conventional methods because it permits the simultaneous and quantitative assessment of the nanoscale and microscale morphologies, and mass-transport properties of the materials with a high nanometer-scale resolution under ambient conditions. It offers a unique means for the assessment and evaluation of the μm-scale nanostructure alignment in polymer films induced by vertical spin-coating (for STMS films), directional solution flow and solvent-vapor penetration (SVP) methods (both for CF-PS-b-PEO films), highly crucial for many potential technological applications using the materials. Through this work, we have identified suitable sample preparation conditions (e.g. solvent, temperature or solution flow rate) for obtaining highly-ordered mesoporous and microdomain structures over a long-range (> 5 μm). For the quantitative assessment of the 1D SMT data, orthogonal regression analysis was employed, providing assessment of the in-plane orientation and size of individual nanostructures with nanometer-scale precision. The analysis of the 1D trajectory data allowed the radius (ca. 11 nm) of cylindrical PEO microdomains to be estimated, yielding results consistent with the AFM results (ca. 14 nm). The distribution of the trajectory angles offered the estimation of the average orientation and order of the nanostructures in domains/grains for a μm-wide region of the polymer films, revealing the higher efficiency of SVP in the nanostructure alignment as compared to the spin coating and solution flow approaches. Systematic SMT measurements across the film depth and along lateral mm-scale distances afforded valuable insights into the shear- and solvent-evaporation-based alignment mechanisms induced by solution flow and SVP/spin coating approaches, respectively. Fluorescence recovery after photobleaching (FRAP) measurements in a SVP-aligned CF-PS-b-PEO film permitted the longer-range mass-transport properties to be probed, reflecting the effective continuity of the aligned cylindrical nanostructures over > 100 μm in length. In this dissertation, FRAP and more importantly SMT methods have provided a unique and useful means for the in-depth characterization of morphology and mass-transport characteristics in thin polymer films under ambient conditions, in confined spaces, and with a nanometer-scale resolution.

Doctor of Philosophy / Department of Chemistry / Daniel A. Higgins / This dissertation describes single-molecule tracking (SMT) studies for the quantitative characterization of one-dimensional (1D) nanostructures in surfactant-templated mesoporous silica monoliths prepared within microfluidic channels. Single molecule diffusion of fluorescent probe molecules within the cylindrical mesopores reflects microscopic morphologies and mass-transport properties of the materials with high temporal and spatial resolution. The pore organization and materials order are initially investigated as a function of sol aging prior to loading into the microfluidic channels. Mesopores in these materials are templated by Cetyltrimethylammonium bromide (CTAB). Wide-field fluorescence videos depict 1D motion of the dyes within the individual mesopores. Orthogonal regression analysis of these motions provides a measure of the mesopore orientation. Channels filled prior to gelation of the sol produce monoliths incorporating large monodomains with highly aligned mesopores. In contrast, channels filled close to or after gelation yield monoliths with misaligned pores that are also more disordered. Two-dimensional (2D) small angle X-ray scattering (SAXS) experiments support the results obtained by SMT. These studies help to identify conditions under which highly aligned mesoporous monoliths can be obtained and also demonstrate the utility of SMT for characterization of mesopore order. The non-ionic surfactant Pluronic F127 is also utilized as the structural-directing agent. The diffusive motions of PDI dyes that are uncharged, cationic and anionic are explored by SMT and fluorescence correlation spectroscopy (FCS). The SMT studies for the uncharged dye show development of 1D diffusion along the flow direction while charged dyes exhibit predominant isotropic diffusion, with each of these behaviors becoming more prevalent as a function of aging time after filling of the microfluidic channels. SMT studies from silica-free F127 gels suggest that partitioning plays a important role in governing the diffusion behavior of the PDI dyes within the surfactant-filled mesopores. FCS results exhibit similar mean diffusion coefficients for all three dyes that suggest these dyes diffuse through similar sample regions. These studies demonstrate that the silica pore walls in the mesoporous silica monoliths remain permeable after gelation and that partitioning of solute species to different regions within the pores plays an important role in restricting the dimensionality of their diffusive motion

A fundamental step in the further developments of comprehensive modelling of the diffusive processes in liquids requires the possibility of obtaining reliable and accurate experimental data of the diffusion and thermodiffusion coefficients of multicomponent liquid systems. In the present work, we perform an experimental investigation of the diffusive properties of binary and ternary liquid systems. Two experimental techniques, the ‘Open Ended Capillary’ technique and the ‘Transient Interferometric Technique’ have been developed. Those techniques have been used for the experimental characterization of several systems composed of 1,2, 3,4-Tetrahydrnaphtalene, Isobutylbenzene and Dodecane at ambient temperature. Those particular species were selected as a simplified multicomponent system modelling the fluids contained in natural crude oils reservoirs. <p>For each of these techniques, experimental set-ups were designed, implemented and calibrated. The procedures for identifying the ternary diffusion coefficients from the measured compositions fields were studied in details. <p>The Open Ended Capillary Technique was applied under gravity condition to study isothermal diffusion binary and ternary systems. Difficulties related to a new procedure for interpreting the data collected at short times of the experiments are highlighted and its implication in the generalization of the technique for the study of multicomponent systems is discussed.<p>The Transient Interferometric Technique was used to perform an experimental study of three binary systems under gravity conditions. It was also applied for the investigation of ternary systems under microgravity condition in the frame of the DSC on SODI experiment, which took place aboard the International Space Station in 2011. The experimental results are reported and the analysis of the accuracy of the technique is presented. The TIT is the first technique ever providing accurate experimental measurements of the complete set of diffusion and thermodiffusion coefficients for ternary liquid systems.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

<p><br></p> <p>A  combustion simulation involves various physiochemical processes, such as molecular and turbulent diffusion, smoke and soot formation, thermal radiation, chemical reaction mechanisms, and kinetics. In the last decade, computational fluid dynamics (CFD) has been increasingly used in combustion modeling. It is critically important to improve and enhance the predictive capabilities of combustion models. This work presents an analysis of two types of diffusion flames: the momentum-dominant jet flames and buoyancy-controlled pool fires. The gap between the existing knowledge of differential molecular diffusion in turbulent high momentum jet flow and the practical applications has been reduced. The importance of mixing modeling in pool fire simulations has been revealed, and enhancement for predicting fire extinction limits has been proposed.</p> <p><br></p> <p>Modeling differential molecular diffusion in turbulent non-premixed combustion remains a great challenge for flamelet models. The laminar flamelet is a key component of a flamelet model for turbulent combustion. One significant challenge that has not been well addressed is the representativity of laminar flamelet for the characteristics of differential molecular diffusion in turbulent combustion problems. Laminar flamelet is generated typically based on two conceptual burner configurations, the opposed jet burner, and the Tsuji burner. They are commonly considered equivalent when dealing with the description of laminar flamelet structures. A difference between them is revealed in this work for the first time when they are used to represent differential molecular diffusion. The traditionally opposed jet burner yields an almost fixed equal diffusion location in the mixture fraction space for the transport of different elements. The Tsuji burner can produce a continuous variation of the equal diffusion location in the mixture fraction space with a slight extension. This variation of the equal diffusion location is shown to be an essential characteristic of turbulent non-premixed combustion, as demonstrated in a laminar jet mixing layer problem, a turbulent jet mixing layer problem, and a turbulent jet non-premixed flame. The Tsuji burner is thus potentially a more suitable choice than the opposed jet burner for laminar flamelet generation that can be consequently used in flamelet modeling of differential molecular diffusion for turbulent non-premixed combustion.</p> <p><br></p> <p>Capturing fire extinction limits in simulations is essential for developing predictive capabilities for fire. In this work, the combined large-eddy simulation (LES) and transported probability density function (PDF) methods are assessed for the predictions of fire extinction. The University of Maryland line burner is adopted as a validation test case. The NIST Fire Dynamics Simulator (FDS) code for LES is combined with an in-house PDF code called HPDF for the fire simulations. The simulation results were verified by using the available experimental data. The combustion efficiency under the different oxygen depletion levels in the oxidizer is analyzed. Fire extinction occurs when the oxygen depletion level reduces to a certain level. The model’s capability to capture this extinction limit is assessed by using the experimental data. Different mixing models and model parameters are examined. It is found that the fire extinction limit is very sensitive to the different mixing models and mixing parameters. The level of sensitivity is higher than in momentum-driven turbulent flames, which suggests the importance of mixing modeling in fire simulations. The existing mixing models need further enhancement for predicting fire extinction. </p> <p><br></p>

[pt] Deposição de parafinas é um dos mais críticos problemas operacionais no transporte de óleo cru, nos dutos que operam em ambientes frios. Portanto, uma predição acurada da deposição de parafinas é crucial para o projeto eficiente de linhas submarinas. Infelizmente, a deposição de parafinas é um processo complexo e os mecanismos de deposição ainda não são bem compreendidos. Visando identificar a importância relativa dos diferentes mecanismos de deposição, dois deles foram investigados: Difusão Molecular e Browniana. Para determinar a quantidade de depósito, as equações de conservação de massa, quantidade de movimento linear, energia, concentração da mistura e concentração da parafina fora da solução foram resolvidas numericamente pelo método de volumes finitos. Um sistema de coordenadas móveis não ortogonais que se adapta a interface do depósito da parafina foi empregado. Apesar da obtenção de uma concordância razoável do perfil de depósito, obtido com os mecanismos selecionados no regime laminar, com resultados disponíveis na literatura, uma discrepância significativa foi observada durante o transiente. O emprego do mecanismo de difusão browniana levou a uma pequena melhora na predição da solução nas regiões sub- resfriadas. A influência do regime turbulento como o mecanismo de difusão molecular também foi investigado, empregando o modelo de turbulência para baixo Reynolds K- (Taxa de dissipação viscosa da energia cinética turbulenta).Os resultados obtidos apresentaram coerência física, com uma taxa menor de aumento do depósito com o tempo, pois a região próxima à interface com temperatura abaixo da temperatura de aparecimento de cristais é menor no regime turbulento. / [en] Wax deposition is one of the major critical operational problems in crude oil pipelines operating in cold environments. Therefore, accurate prediction of the wax deposition is crucial for the efficient design of subsea lines. Unfortunately, wax deposition is a complex process for which the mechanisms are still not fully understood. Aiming at the identification of the relative importance of the different deposition mechanisms, two of them were investigated: Molecular and Brownian Diffusion. To determine the amount of deposit, the conservation equations of mass, momentum, energy, concentration of the mixture and wax concentration outside the solution were numerically solved with the finite volume method. A non-orthogonal moving coordinate system that adapts to the wax interface deposit geometry was employed. Although for the laminar regime, the deposition profile predicted with the selected deposition mechanisms presented a reasonable agreement with available literature results for the steady state regime, a significant discrepancy was observed during the transient. The employment of the Brownian diffusion mechanism led to only a small improvement in the transient solution prediction in sub-cooled regions. The influence of the turbulent regime with the Molecular diffusion mechanism was also investigated by employing the Low Reynolds ê&#8722;turbulence model. The results obtained were physically coherent, presenting a smaller deposit thickness, since the region with temperature below the wax appearance temperature is smaller in the turbulent regime.

[pt] Deposição de parafinas, com alto peso molecular, na parede interna de linhas submarinas de produção e transporte continua a ser um problema crítico encontrado pela indústria de petróleo. Uma previsão precisa das taxas de deposição e da distribuição espacial da parafina depositada é uma informação fundamental para o projeto de linhas submarinas. Uma revisão minuciosa da literatura mostrou que não existem informações suficientes para determinar quais são os mecanismos relevantes para a deposição da parafina. No entanto, a maioria das simulações disponíveis emprega a difusão molecular como único mecanismo de deposição. Portanto, no presente trabalho realiza-se uma análise numérica do processo de deposição da parafina em dutos, utilizando o modelo de difusão molecular e compara-se com dados experimentais obtidos em um experimento simples e básico em um duto de seção retangular. Duas formulações matemáticas são utilizadas para modelar a taxa de transporte de parafina para a parede do duto; a primeira formulação é uni- dimensional e estima a taxa de deposição da parafina a partir do gradiente de temperatura; a segunda formulação é bi-dimensional e a taxa de deposição é determinada em função do gradiente de concentração da parafina. O método de volumes finitos é empregado para resolver as equações de conservação de massa, energia e da fração de massa juntamente com a equação difusiva que descreve o crescimento do depósito de parafina. Adicionalmente, investigou-se a influência do calor latente no balanço de energia. Verificou-se que o calor latente acelera o processo de deposição, mas não influencia na espessura final depositada, após atingir o regime permanente. Os resultados obtidos apresentam diferenças significativas com relação aos dados experimentais, indicando que a difusão molecular não é o único mecanismo relevante para a deposição de parafina. / [en] Deposition of high molecular weight para±ns on the inner wall of subsea production and transportation pipelines continues to be a critical operati- onal problem faced by the petroleum industry. The accurate prediction of wax deposition rates and deposited wax spatial distribution would be an invaluable information for the design of subsea pipelines. A critical review of the literature conducted lead to the conclusion that there is not enough experimental evidence to determine which are the more relevant mecha- nisms responsible for wax deposition. However, the majority of available simulations employ the molecular diffusion model as the only deposition mechanism. Therefore, in the present work, a numerical analysis of the wax deposition in ducts is performed employing the molecular diffusion model and a comparison with experimental data of a simple and basic experiment in a rectangular cross section duct is performed. Two mathematical mo- dels are investigated; the first formulation is one- dimensional and the wax deposition rate is determined from the temperature gradient. The second formulation is two-dimensional and the wax deposition rate is a function of the para±n concentration gradient. The finite volume method was selec- ted to solve the conservation equations of mass, energy and mass fraction, coupled with a difusive equation to describe the growth of the wax deposi- tion. Additionally, the influence of the para±n latent heat was investigated. It was verified that the latent heat accelerates the deposition process, but does not affect thenal wax thickness after reaching the steady state regime. The results obtained presented signifficant differences between experiments and computation, indicating that molecular diffusion might not be the only relevant mechanism responsible for wax deposition.

[pt] O Petróleo é formado por um conjunto de hidrocarbonetos. No reservatório, devido à altas pressões e temperaturas, encontra-se na forma de líquido. Conforme o petróleo escoa, a pressão cai assim como a temperatura, devido a perda de calor para o ambiente marinho, causando a liberação do gás dissolvido no petróleo tornando o escoamento bifásico. Adicionalmente, caso a temperatura caia abaixo da temperatura inicial de cristalização (TIAC), ocorre precipitação dos cristais, formando uma fase sólida que se deposita na parede interna das tubulações. Deposição de parafinas é um dos mais críticos problemas operacionais na produção e transporte de petróleo em linhas submarinas. O presente trabalho analisa numericamente a deposição de parafina em escoamento multifásico no interior de dutos para diversos padrões de fluxo. Investiga-se ainda a influência da presença da água e dos ângulos de inclinação da tubulação com a horizontal nas taxas de deposição. Para prever o escoamento multifásico utilizou-se o modelo de deslizamento e a deposição da parafina foi determinada baseada no modelo de difusão molecular. A modelagem desenvolvida foi validada com a simulação do escoamento ao longo de um duto curto, reproduzindo condições experimentais de laboratório. Os resultados obtidos para a espessura do depósito apresentaram excelente concordância com os dados experimentais e com os dados obtidos com o simulador comercial OLGA. Analisou-se o escoamento entre um poço produtor e uma plataforma na Bacia de Campos, onde determinou-se o impacto na perda de carga devido a diminuição do diâmetro interno da tubulação causada pelo aumento da espessura dos depósitos. Os resultados obtidos destes estudos apresentaram boa coerência física e razoável concordância com relação aos dados experimentais. / [en] Crude oil is formed by several hydrocarbons. At the reservoir, due to high pressures and temperatures, it is found in the liquid form. As the oil flows, its pressure drops as well as its temperature, due to a heat loss to the ambient, causing liberation of the gas dissolved in the oil and it becomes a two-phase flow. Further, if the temperature drops below the initial crystallization temperature, crystals precipitation occurs, forming a solid phase deposit at the inner pipeline walls. Wax deposition is one of the most critical operational problems regarding oil flow through subsea pipelines. This work, wax deposition in a multiphase flow is numerically predicted. The influence of a water phase and pipe inclination angle in the deposition rate is investigated. The Drift Flux Model was employed to predict the multiphase flow and the wax deposition was determined based on a Molecular Diffusion Model. The methodology was validated by investigating the flow in a short pipe, reproducing laboratory experimental conditions. The wax deposit thickness presented a excellent agreement with the experimental data and against results of commercial code OLGA. An existing oil production well in Campos Basin was modeled, and the impact in pressure drop due to cross section area reduction caused by progressive wax deposition on the pipe wall. The results obtained in this study demonstrated good physical consistency and a reasonable agreement with the compared experimental database.

Supported lipid bilayers have been used as an artificial model of biological membranes and their interaction with 5 selected antimicrobial peptides was studied by several experimental techniques, mainly ellipsometry, laser scanning microscopy and fluorescence correlation spectroscopy. The thesis explains basic principles of the applied techniques focusing on their aspects relevant to characterization of lipid bilayers. The biological significance of antimicrobial peptides, their modes of interaction with membranes and the basic characteristics of the selected peptides are briefly discussed. The following text describes the main types of experimental studies performed and the interpretation of their results. Peptide-induced changes in lipid bilayer morphology were characterized by ellipsometry and laser scanning microscopy. Most interesting effects were observed in the case of melittin, which induced formation of long lipid tubules protruding from the bilayer. Lipid lateral diffusion measured by fluorescence correlation spectroscopy can provide information on bilayer organization on length-scales below resolution of optical microscopy.