Search for dissertations about: "Free diffusion"

Showing result 1 - 5 of 208 swedish dissertations containing the words Free diffusion.

  2. 1. Pushing diffusion MRI towards new dimensions

    Author : Joao Martins; Fysikalisk kemi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NMR; MRI; diffusion; relaxation; multidimensional diffusion MRI; relaxation-diffusion correlations; Laplace NMR; porous media; tissue microstructure; heterogeneity; anisotropy;

    Abstract : Diffusion-MRI techniques allow the non-invasive investigation of microstructural changes in living tissues. However, a detailed interpretation of the data is complicated by the fact that multiple microscopic environments with varying diffusion properties all contribute to the measured signal. READ MORE

  4. 2. Small Molecule Diffusion in Spherulitic Polyethylene : Experimental Results and Simulations

    Author : Alessandro Mattozzi; Ulf W. Gedde; Alan H. Windle; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; diffusion; polyethylene; poly ethylene-co-octene ; free volume; morphology; intermediate phase; spherulite; Monte Carlo simulation; Polymer chemistry; Polymerkemi;

    Abstract : The diffusion of small-molecule penetrants in polyethylene is hindered by impenetrable crystals and by the segmental constraints imposed by the crystals on the penetrable phase. Liquid and vapour n-hexane sorption/desorption measurements were performed on metallocene catalyzed homogenous poly(ethylene-co-octene)s. READ MORE

  5. 3. Water diffusion and free volume in hydrophilic polymers

    Author : Charlotte Trotzig; Centrum för analys och syntes; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Physical chemistry; free volume; self-diffusion; degree of crystallinity; glass transition temperature; tensile storage modulus; surface tension; isotherm; HPMC; PEO; water; triacetin; clay; Macromolecular chemistry; dynamic mechanical analysis; Fysikalisk kemi; differential scanning calorimetry; nuclear magnetic resonance; positron annihilation; Makromolekylär kemi;

    Abstract : During moisture uptake in polymers, the diffusion of the water molecules is believed to occur via unoccupied voids. These voids are called free volume cavities and their sizes are continuously altered when the moisture content in the polymer is enhanced. READ MORE

  6. 4. Hydrogen in nano-sized metals : Diffusion and hysteresis effects

    Author : Wen Huang; Björgvin Hjörvarsson; Max Wolff; Gavin Walker; Uppsala universitet; []
    Keywords : Hydrogen; diffusion; hysteresis; optical technique; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Abstract : Metal hydrides can be used as hydrogen storage materials for fuel cells and batteries, and as sensors for detecting hydrogen gas. The use of metal hydrides for hydrogen storage can be hindered by poor kinetics and low capacity. Moreover, poor sensitivity, long recovery and response time, limit the applications of metal hydrides as hydrogen sensors. READ MORE

  7. 5. Developing novel diffusion MRI methods for comprehensive analysis of restricted and anisotropic self-diffusion system

    Author : Hong Jiang; Fysikalisk kemi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; MRI; diffusion; tissue microstructure; heterogeneity; diffusion encoding; q-vector; ;

    Abstract : Diffusion MRI is a non-invasive imaging technique used to study the microstructural properties of biological tissues by observing the self-diffusion of water molecules. Traditional diffusion MRI methods, based on the pulsed gradient spin-echo sequence, employ magnetic field gradients to encode information about translational motion. READ MORE