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 47 for “"Water Diffusion"”.
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A QUASIELASTIC NEUTRON SCATTERING STUDY OF WATER DIFFUSION IN FROG MUSCLE
… structure and dynamics of cytoplasmic water in the cells of organs and tissues are not well-understood. Much work has been done using various experimental techniques to study the properties of water in living systems, yet there is no generally accepted model describing the interaction …
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Neutron scattering studies of water diffusion near the interface of model cell membranes
… between peptide-lipid domains and the hydrating water. Therefore, the dynamics of the membrane-associated water and its interaction with embedded proteins remain some of the most fundamental issues in biological physics today. Single-supported lipid bilayers (SSLBs) provide model systems for …
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Probing the effect of microstructure on water diffusion in engineered or biological materials with MRI
Water diffusion within skeletal muscles is a complex mass transport process due to the presence of barriers at multiple scales and the anisotropic structure of muscles. Magnetic Resonance Imaging (MRI) is an effective non-invasive technology for studying water transport in biological or engineered …
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Two approaches to white matter nuclear magnetic resonance : water diffusion and inhaled laser-polarized xenon
Thesis (Ph. D.)--Massachusetts Institute of Technology, Whitaker College of Health Sciences and Technology, 1997.
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Numerical methods for simulating diffusion in cellular media
Diffusion imaging is a relatively recent branch of magnetic resonance imaging that produces images of human physiology through diffusion of water molecules within the body. One difficulty in calculating diffusion coefficients, particularly in the brain, is the multitude of natural barriers to water …
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Effect of cross-linking on the diffusion of water, ions and small molecules in hydrogels
Understanding the diffusion of small molecules in hydrogel system is of major importance in a variety of applications including drug delivery systems, tissue engineering and contact lens. Cross-linking density of hydrogels has been commonly used to tune key parameters like mesh size and molecular …
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THE EFFECT OF WATER ON THE PHYSICAL PROPERTIES OF EPOXIDES
The effect of water absorption in epoxide adhesives, both in bulk and joint forms, was examined. Boiling-water immersion was found to be a suitable technique to accelerate water diffusion in bulk epoxides. The boiling-water diffusion was found to be Fickian in epoxides except for the DOM system’, …
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The relationship between neurocognitive disorders, prospective memory impairment and white matter damage in clade C HIV-positive subjects
… prospective memory, cognitive function and Diffusion tensor imaging (DTI)/ White matter integrity of human immunodeficiency virus (HIV) positive individuals in the Western Cape. We hypothesize that: 1. Individuals infected with HIV will exhibit significantly poorer microstructural integrity …
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Lattice Boltzmann method for integrating the Bloch equation in muscle fibers and microvessels
… can measure the local properties of directional water diffusion and lipid concentration in the human muscle. Strong correlations have also been found between overall fitness and MRI measurements related to the transport of water inside the muscle fibers. In addition to water diffusion within the …
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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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Proton magnetic resonance of wood and water in wood
… protons in solid wood and compartmentalized water in the wood cell walls and lumens. A lineshape second moment study found the second moment of protons in oven dry wood to be about 23% lower than the rigid lattice calculation, indicating a rigid structure with some anisotropic molecular …
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Multiscale Tortuous Diffusion in Anion- and Cation-Exchange Membranes: Exploration of Counterions, Water Content, and Polymer Functionality
Fundamental understanding of water transport and morphology is critical for improving ion conductivity in polymer electrolyte membranes (PEMs). Herein, we present comprehensive water transport measurements comparing anion-exchange membranes (AEMs) based on ammonium-functionalized poly(phenylene …
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Characterization of metal artifacts in diffusion tensor imaging for spinal cord applications
Diffusion Tensor Imaging (DTI) is a magnetic resonance imaging (MRI) technique used to measure in-vivo anisotropic water diffusion. This can give useful information regarding white matter integrity and has the potential to provide important biomarkers in spinal cord injury. One of the largest …
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Advanced characterization of transport and microstructural properties in membrane materials
… are employed in a variety of sustainable water treatment and energy conversion technologies. Advancing membrane materials for new separations includes unraveling the complex structure-property relationships that govern water and salt transport in conjunction with scaling processing …
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Three dimensional mapping of lingual myoarchitecture
… based on direction specific differences in water diffusion. Muscle tissue in particular exhibits significant diffusion anisotropy in the direction of fibers, from which diffusion imaging is able to infer fiber direction. In this thesis research, several diffusion weighted MRI signal …
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The role of denitrification in the nitrogen cycle of New England salt marshes
… tidal creekbottoms is a major sink for groundwater nitrate of terrestrial origin. I studied creekbottom denitrification by direct measurements of N₂ fluxes in closed chambers against a low-N₂ background. I undertook experiments and simulation modeling of sediment N₂ fluxes in closed chambers …
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Spatially Selective 2D RF Inner Field of View (iFOV) Diffusion Kurtosis Imaging (DKI) of the Pediatric Spinal Cord
Magnetic resonance based diffusion imaging has been gaining more utility and clinical relevance over the past decade. Using conventional echo planar techniques it is possible to acquire and characterize water diffusion within the central nervous system (CNS); namely in the form of Diffusion …
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Fabrication of Micropatterned Hydrogels for Cell Culture
… structures, the hydrogen bonding towards water makes them hydrophilic compounds. Hydrogels contain 95% ~ 99% water as the swelling agent and have the characteristics of extracellular matrix. Therefore, they are suitable for cell growth and appropriate for forming cell culture. Hydrogels …
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Thermal Analysis and Cation Doping of Nafion Membranes
… by decreasing proton conductivity and water content in</p> <p>perfluorosulfonic membranes such as Nafion. Hydration of the membrane is important</p> <p>for cell durability and longevity; low relative humidity accelerates membrane</p> <p>degradation. Cations can exchange with the proton …
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Advanced Methods for Diffusion MRI Data Analysis and their Application to the Healthy Ageing Brain
Diffusion of water molecules in biological tissues depends on several microstructural properties. Therefore, diffusion Magnetic Resonance Imaging (dMRI) is a useful tool to infer and study microstructural brain changes in the context of human development, ageing and neuropathology. In this thesis, …
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