Sökning: "ultraviolet UV"

Visar resultat 16 - 20 av 109 avhandlingar innehållade orden ultraviolet UV.

1. 16. Computational chemistry studies of UV induced processes in human skin

   Författare :Jonas Danielsson; Aatto Laaksonen; Villy Sundström; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photochemistry; Theoretical chemistry; Density functional theory; UV effects; TD-DFT; enzyme catalysis; DNA damage; Molecular dynamics; Physical chemistry; Fysikalisk kemi;

   Sammanfattning : This thesis presents and uses the techniques of computational chemistry to explore two different processes induced in human skin by ultraviolet light. The first is the transformation of urocanic acid into a immunosuppressing agent, and the other is the enzymatic action of the 8-oxoguanine glycosylase enzyme. LÄS MER

3. 17. Concepts for compact solid-state lasers in the visible and UV

   Författare :Sandra Johansson; Fredrik Laurell; Patrick Georges; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nonlinear optics; frequency conversion; visible lasers; ultraviolet lasers; KTiOPO4; BiBO; BBO; quasi phase-matching; birefringent phase-matching; solid-state lasers; Physics; Fysik;

   Sammanfattning : In many fields, scientific or industrial, optical devices that can be tailored in terms of spectral qualities and output power depending on the application in question are attractive. Nonlinear optics in combination with powerful laser sources provide a tool to achieve essentially any wavelength in the electromagnetic spectrum, and the advancement of material technology during the last decade has opened up new possibilities in terms of realising such devices. LÄS MER

4. 18. Thin-film ultraviolet light-emitting diodes realized by electrochemical etching of AlGaN

   Författare :Michael Alexander Bergmann; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; thin-film flip-chip; light-emitting diodes; UVB; AlGaN; thermocompression bonding; substrate removal; ultraviolet light; electrochemical etching; heterogeneous integration; LEDs;

   Sammanfattning : Ultraviolet (UV) light sources have a direct impact on everyone’s life. They are used to sterilize surfaces as well as for water purification. In addition, they are used in green houses to enhance health-promoting substances in plants, for phototherapy to treat skin diseases, for sensing and material curing. LÄS MER

5. 19. Evolutionary ecology of ultraviolet-B radiation stress tolerance in amphibians

   Författare :Maarit Pahkala; Trevor Beebee; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; amphibians; anomalies; embryonic development; geographic variation; growth; Rana arvalis; Rana temporaria; survival; UV-B radiation; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; populationsbiologi; Population Biology;

   Sammanfattning : During the last decades many amphibian species and populations have experienced declines and extinctions in different parts of the world. Anthropogenic activities are believed to account for these declines, and one of the hypothesized causes has been the increased level of ultraviolet-B (UV-B) radiation due to depletion of the stratospheric ozone layer. LÄS MER

7. 20. UV-induced DNA damage in humans

   Författare :Vladimir J Bykov; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :32P-HPLC; photoproducts; DNA repair; solar simulated radiation; erythema; sunscreens; humans;

   Sammanfattning : Ultraviolet radiation is considered to be the most harmful part of solar energy affecting man. The depletion of the ozone layer around the Earth increases the total exposure to UV-light. The incidence of skin cancer in man has been shown to be associated with exposure to solar radiation, especially to UV-light. LÄS MER