Sökning: "self diffusion"

Visar resultat 1 - 5 av 214 avhandlingar innehållade orden self diffusion.

  1. 1. Insights into Materials Properties from Ab Initio Theory : Diffusion, Adsorption, Catalysis & Structure

    Författare :Andreas Blomqvist; Rajeev Ahuja; Christopher Wolverton; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Molecular dynamics; Diffusion; Catalysis; Adsorption; Random structure search; Hydrogen-storage materials; Phase-change materials; Defects and diffusion; Defekter och diffusion; Surfaces and interfaces; Ytor och mellanytor; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this thesis, density functional theory (DFT) calculations and DFT based ab initio molecular dynamics simulations have been employed in order to gain insights into materials properties like diffusion, adsorption, catalysis, and structure. In transition metals, absorbed hydrogen atoms self-trap due to localization of metal d-electrons. LÄS MER

  2. 2. NMR Self-Diffusion Studies and Stability Studies of Emulsions

    Författare :Ingrid Lönnqvist; LTH Ingenjörshögskolan vid Campus Helsingborg; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coalescence; emulsion stability; size distribution; restricted diffusion; self-diffusion coefficient; self-diffusion PGSE NMR; surfactant; emulsifier; continuous phase; microemulsion; phase diagram; emulsion; multiple emulsion; cream; conductivity; Physics; Fysik; Chemistry; Kemi;

    Sammanfattning : The aim of this study is to characterize emulsion systems by self-diffusion PGSE NMR methods. The specifics of the emulsions studied are all taken from the literature and they are of the W/O or O/W type stabilized with different emulsifiers. LÄS MER

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

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

    Sammanfattning : 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. LÄS MER

  4. 4. Nuclear magnetic resonance studies of water self-diffusion in porous systems

    Författare :Daniel Topgaard; Fysikalisk kemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diffusion diffraction; nonfreezing; anisotropy; tortuosity; cross relaxation; emulsion; starch; cellulose; porous material; water; NMR; self-diffusion; Physical chemistry; Fysikalisk kemi;

    Sammanfattning : Proton nuclear magnetic resonance (NMR) was used to study the self-diffusion of water in porous systems that respond to a change in water content in order to elucidate the porous structure and the properties of the confined water. In the carbohydrate systems cellulose fibers and starch granules, water is free to move throughout the porous objects, albeit with a rate reduced from the value of the bulk liquid, The reduction is related to the tortuosity of the pore space filled by water. LÄS MER

  5. 5. Electrochemical Studies of Redox Properties and Diffusion in Self-Assembled Systems

    Författare :Johan Kostela; Mats Almgren; Maja Elmgren; Martin Malmsten; Renata Bilewicz; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical chemistry; electrochemistry; self-assembly; bicontinuos cubic phase; redox potential; diffusion; Fysikalisk kemi; Physical chemistry; Fysikalisk kemi;

    Sammanfattning : In this thesis electron transfer reactions and diffusion of redox molecules in three different types of self-aggregated structures are investigated. Electrochemistry was used to investigate the redox potential and diffusion coefficients for redox active molecules with different polarity. The first aggregate system studied was the micellar phase. LÄS MER