Sökning: "B Persson"

Visar resultat 1 - 5 av 70 avhandlingar innehållade orden B Persson.

  1. 1. Atomic Scale Modelling in Photoelectrocatalysis : Towards the Development of Efficient Materials for Solar Fuel Production

    Författare :Giane B. Damas; Carlos Moyses Araujo; Rajeev Ahuja; Clas Persson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photocatalytic hydrogen production; polymeric materials; donor-acceptor architecture; small molecules; density functional theory; hydrogen binding free energies; exciton binding energies; electrocatalysis; carbon dioxide conversion; formic acid production; Sn-based electrodes; Tin oxides; Ru-complexes; Metal Organic Frameworks; carbon dioxide capture.;

    Sammanfattning : Using sunlight to produce valuable chemicals has been pointed out as an interesting alternative to deal with the well-known environmental problem related to the use of fossil fuels for energy generation. Thus, it is crucial for this field the development of novel photocatalysts that could drive the uphill reactions with high efficiency while presenting low price and toxicity. LÄS MER

  3. 2. Spin Vortices, Interlayer Exchange, and Magnetocalorics in Multilayers

    Författare :Milton Persson; Vladislav Korenivski; David B. Haviland; Coriolan Tiusan; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spin vortex pairs; bimerons; RKKY; finite size effects; nanostructure magnetocalorics; atomistic spin dynamics; nanocalorimetry; Spinvirvelpar; bimeron; RKKY; finita storlekseffekter; magnetkalorimetri i nanostrukturer; atomistisk spindynamik; nanokalorimetri; Material and Nano Physics; Material- och nanofysik;

    Sammanfattning : In this thesis we study strongly coupled pairs of spin vortices, in a configurationsuch that the cores attract while external fields act to pull them apart, with potential applications in magnetic random access memory (MRAM) and oscillators.Inertial decoupling of the cores has been studied and can be achieved with weak nanosecond pulses by the help of anharmonicity. LÄS MER

  4. 3. The aging brain and changes in cognitive performance : Findings from morphometry and quantitative susceptibility mapping of iron

    Författare :Ninni Persson; Håkan Fischser; Kristine B. Walhovd; Stockholms universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; brain aging; volumes; ndividual differences; QSM; cognitive aging; iron; episodic memory; fluid-; crystalized abilities; sex differences; gender differences; Psychology; psykologi;

    Sammanfattning : Brain aging is a heterogeneous phenomenon, and this thesis illustrates how the course of aging can vary within individuals over time and between individuals as a function of age, sex, and genetic variability. We used two contrasts from magnetic resonance imaging (MRI), namely spin-lattice T1-weighted imaging, and quantitative susceptibility mapping (QSM) from gradient-echo images, to picture the aging brain, by means of morphometric measures and brain-iron concentrations. LÄS MER

  5. 4. Some new results concerning general weighted regular Sturm-Liouville problems

    Författare :Mervis Kikonko; Lars-Erik Persson; Peter Wall; Angelo B. Mingarelli; Alexey Karapetyants; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Partial differential equations; Sturm-Liouville problem; Right-definite; left-definite; non-definite; indefinite; Dirichlet problem; spectrum; eigenvalues; non-real eigenvalues; Richardson number; Richardson index; turning point; Mathematics; Matematik;

    Sammanfattning : In this PhD thesis we study some weighted regular Sturm-Liouville problems in which the weight function takes on both positive and negative signs in an appropriate interval [a,b]. With such  problems there is the possible existence of non-real eigenvalues, unlike in the definite case (i.e. LÄS MER

  7. 5. Phase transformation and surface chemistry of secondary iron minerals formed from acid mine drainage

    Författare :Jörgen Jönsson; Lars Lövgren; Per Persson; Staffan Sjöberg; Douglas B Kent; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Inorganic chemistry; schwertmannite; goethite; lepidocrocite; acid mine drainage; sulphate; natural organic matter; mineral surface; infrared spectroscopy; EXAFS; XRD; ternary surface complex; copper II ; cadmium II ; lead II ; zinc II ; Oorganisk kemi; Inorganic chemistry; Oorganisk kemi; Inorganic Chemistry; oorganisk kemi;

    Sammanfattning : The mining of sulphidic ore to extract metals such as zinc and copper produces huge quantities of waste material. The weathering and oxidation of the waste produces what is commonly known as Acid Mine Drainage (AMD), a dilute sulphuric acid rich in Fe(II) and heavy metals. LÄS MER