Sökning: "electron density"

Visar resultat 16 - 20 av 733 avhandlingar innehållade orden electron density.

1. 16. Parietal cell regeneration in rat gastric mucosal wounds : a quantitative light and electron microscopical study

   Författare :Håkan Blom; Herbert Helander; Umeå universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Rat; gastric mucosa; gastric wounds; parietal cells; re­generation; pyloroplasty; truncal vagotomy; antrectomy; pen­tagastrin; cimetidine; carbacholine; stereology; light microscopy; electron microscopy; pH-studies;

   Sammanfattning : The aims of the study were to obtain a method with which it would be possible to produce standardized wounds in the gastric mucosa, and to follow the regeneration of the acid producing parietal cells in those lesions during different experimental conditions. Quantitative methods applied to light and electron microscopy were used. LÄS MER

3. 17. Liquid-Jet-Target Microfocus X-Ray Sources : Electron Guns, Optics and Phase-Contrast Imaging

   Författare :Tomi Tuohimaa; Hans M. Hertz; Stephen Wilkins; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electron-impact; x-ray; brightness; liquid-jet-target; phase-contrast imaging; Engineering physics; Teknisk fysik;

   Sammanfattning : This Thesis describes the development of an electron-impact microfocus x-ray source and its application for phase-contrast imaging. The source is based on a novel, liquid-jet target concept. Stable and continuous operation can be achieved at substantially higher electron-beam power densities than conventional solid target based systems. LÄS MER

4. 18. Non-collinear Magnetism in d- and f-electron Systems

   Författare :Raquel Lizárraga Jurado; Olle Eriksson; Lars Nordström; Axel Svane; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Non-collinear magnetism; spin spirals; first principles; density functional theory; Fermi surfaces; electronic structure; f-electron systems; Fysik;

   Sammanfattning : In this thesis, non-collinear magnetism has been studied by using density functional theory and the augmented plane wave method with local orbitals (APW+lo). Two conditions for non-collinear instabilities have been identified in this thesis. First, the Fermi energy should cut through both spin up and down states. LÄS MER

5. 19. Chemistry and Physics of Cu and H2O on ZnO Surfaces : Electron Transfer, Surface Triangles, and Theory

   Författare :Matti Hellström; Kersti Hermansson; Peter Broqvist; Daniel Spångbeg; Jörg Behler; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; catalysis; density functional theory; SCC-DFTB; band-filling correction;

   Sammanfattning : This thesis discusses the chemistry and physics of Cu and H2O on ZnO surfaces, based primarily on results from quantum chemical calculations. The underlying context is heterogeneous catalysis, where Cu/ZnO-mixtures are used in the industrial synthesis of methanol and in the water gas shift reaction. LÄS MER

7. 20. Dynamics and Fluctuations in Single-Electron Tunneling Devices

   Författare :Niklas Dittmann; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; quantum dot; time-dependent density-functional theory; perturbation theory; single-electron source;

   Sammanfattning : In recent years, it has been routinely achieved to build nanoscale electronic devices, which generate current pulses carrying only a single elementary charge. Realizations of these single-electron emitters are based on time-dependently driven quantum dots, on single-electron turnstiles built from superconductor/normal-metal hybrid structures, and also on nanosystems employing Lorentzian voltage pulses or surface acoustic waves. LÄS MER