Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 39 for “"Diffusion measurements"”.
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NMR Studies of Solid-Supercritical Fluid Mixtures and a New Technique for NMR Diffusion Measurements
Solid solubilities of naphthalene in supercritical carbon dioxide have been measured near the upper critical end point of the binary mixture by using a novel, in situ NMR technique. The pressure-temperature trace of the solid-liquid-gas phase line that terminates at the upper critical end point was …
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Microscopic diffusion measurements with nanoporous materials: complementary benefits of infrared microimaging and pulsed field gradient NMR
… on the subject of two microscopic techniques of diffusion measurement, namely infrared (IR) microimaging and pulsed field gradient (PFG) NMR. The dissertation contains mainly five chapters. The first chapter introduces diffusion phenomena in general and concisely explains the importance and the …
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Nmr and Polarization Microscopy Studies of Sodium Alkyl Carboxylate Solids and Melts
… and Fourier transform NMR. Both the ('1)H self-diffusion measurements and the ('23)Na spin-lattice relaxation time, T(,1), and quadrupole coupling constant,
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Diffusion of organic liquids : pressure, temperature studies
… cell has been designed and used for self-diffusion measurements at pressures up to 1500 x 10⁵ Nm⁻² and for a temperature range from 283.2 K to 328.2K. It has been shown how the bulk flow that occurs in the cell can be calculated and the diffusion coefficient obtained. Self-diffusion …
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Diffusion of organic liquids : pressure, temperature studies
… cell has been designed and used for self-diffusion measurements at pressures up to 1500 x 10⁵ Nm⁻² and for a temperature range from 283.2 K to 328.2K. It has been shown how the bulk flow that occurs in the cell can be calculated and the diffusion coefficient obtained. Self-diffusion …
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Transport properties of micellar solutions and microemulsions.
… phase diagram was confirmed.Conductivity measurements were made in the isotropic liquid regions of these systems and self-diffusion measurements were made in the isotropic liquid regions of the C[12]E[4]-water and C[13]E[6]-water systems, in order to elucidate the structures of these …
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Magnetic Resonance Studies of Three-Phase Heterogeneous Catalytic Hydrogenation Reactions
… and spatially resolved 2D NMR relaxation and diffusion measurements were used to characterize reaction species. Experiments were carried out on the species in their pure state as bulk liquids and imbibed in the catalyst material (Pd/Al2O3). Single component liquids as well as mixtures were …
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Magnetic resonance diffusion imaging and spectral localization: New methods and their quantitative applications
… interest, in recent years, in the measurement of diffusion of water and metabolites in living systems by magnetic resonance (MR) techniques. Knowledge of the diffusion coefficients of the molecules can yield unique information about microstructure and function of tissue. We have developed a method …
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Diffusion and Evaporation of Nitrogen on Tungsten (100)
Surface diffusion and evaporation from a layer of nitrogen chemisorbed on the (100) plane of tungsten has been examined using Auger spectroscopy. The initial localized deposit required for diffusion measurements in a concentration gradient is created by a highly collimated molecular beam. The …
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Defect Engineering for Controlling Semiconductor Diffusion
… toward the surface and results in increased diffusion. The second mechanism involves direct creation and generation of defects at the surface bonds. We show through self-diffusion measurements in silicon that defect concentrations deep in the semiconductor bulk can be varied controllably over …
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Advanced characterization of transport and microstructural properties in membrane materials
… These modifications impact water and salt diffusion as well as microstructural characteristics in the membrane materials, yet the detailed relationships between membrane performance, processing conditions, and transport properties remain to be fully characterized. Although extensive …
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Learning motion patterns using hierarchical Bayesian models
… similar to learning motion patterns arise. Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is one of the first methods to visualize and quantify the organization of white matter in the brain in vivo. Using methods of tractography segmentation, one can connect local diffusion …
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Radiation-enhanced diffusion of oxygen-18 in uranium dioxide thin films
Anion radiation enhanced diffusion (RED) and thermal diffusion of a buried 18O tracer layer in thin film UO2 was measured using Secondary-Ion Mass Spectroscopy (SIMS). Thin films were grown using a dedicated magnetron sputtering chamber. Samples were irradiated with 1.8 MeV Kr+ over a temperature …
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Examining the Association between Brain MRI Measures at 7 Tesla and cognition following COVID-19 Infection
… COVID-19 illness and determined whether advanced diffusion magnetic resonance imaging measures within subcortical brain structures of the limbic system were related to neurological, respiratory, psychiatric, and gastric symptoms experienced during the acute phase of illness. Cognitive and …
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Investigating transport of charged nanoparticles by multiphoton fluorescence correlation spectroscopy (MPFCS)
… utilization to probe the effect of charge on the diffusion of quantum dot (QD) nanocrystals in collagen and collagen-hyaluronan (HA) composite gel models of human colon adenocarcinoma (LS174T). The MPFCS system was integrated with a multiphoton laser-scanning microscope (MPLSM) to enable …
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Probing Transport of Ion Dense Electrolytes using Electrophoretic NMR
… and ion motion. The combination of mobilities measurements and diffusion measurements provides some new insight of ion aggregation. We explore ion transport of ionic liquids inside the ionic polymer Nafion as a function of hydration level. When ionic liquids diffuse inside ionic polymers, …
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Structure and Dynamics of Associative Polymer Gels
… which governs their properties such as self-diffusion, relaxation, and creep. In this thesis, a combined experimental and computation approach was used to provide new insight into the structure and dynamics of associative networks on various length and time scales, with the goal of …
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Diffusion and the thermal stability of amorphous copper-zirconium
Measurements have been made of diffusion and thermal relaxation in amorphous CU50Zr50. Samples were prepared by melt-spinning under vacuum. Diffusion measurements were made over the temperature range from 317 to 385 C, using Ag and Au as substitutional impurities, by means of Auger electron …
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Monitoring apoptosis in intact cells by high-resolution magic angle spinning 1H NMR spectroscopy
… increased LD size. In this thesis, an NMR-based diffusion method is described for differentiating between control, apoptotic and necrotic cells. I demonstrate that as apoptosis-induced LDs become larger, the diffusion coefficient of NMR-visible lipids decreases. Therefore, diffusion measurements …
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