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- Frank, J., et al.
(författare)
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Dietary flavonoids with a catechol structure increase alpha-tocopherol in rats and protect the vitamin from oxidation in vitro
- 2006
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 47:12, s. 2718-2725
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Tidskriftsartikel (refereegranskat)abstract
- To identify dietary phenolic compounds capable of improving vitamin E status, male Sprague-Dawleyrats were fed for 4 weeks either a basal diet ( control) with 2 g/kg cholesterol and an adequate content of vitamin E or the basal diet fortified with quercetin ( Q), (2)-epicatechin (EC), or (1)-catechin ( C) at concentrations of 2 g/kg. All three catechol derivatives substantially increased concentrations of alpha-tocopherol (alpha-T) in blood plasma and liver. To study potential mechanisms underlying the observed increase of alpha-T, the capacities of the Flavonoids to i) protect alpha-T from oxidation in LDL exposed to peroxyl radicals, ii) reduce alpha-tocopheroxyl radicals (alpha-T-.) in SDS micelles, and iii) inhibit the metabolism of tocopherols in HepG2 cells were determined. All flavonoids protected alpha-T from oxidation in human LDL ex vivo and dose-dependently reduced the concentrations of alpha-T-.. None of the test compounds affected vitamin E metabolism in the hepatocyte cultures. In conclusion, fortification of the diet of Sprague-Dawley rats with Q, EC, or C considerably improved their vitamin E status. The underlying mechanism does not appear to involve vitamin E metabolism but may involve direct quenching of free radicals or reduction of the alpha-T-. by the flavonoids.
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- Simon, Daniel, 1978-, et al.
(författare)
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Admittance spectroscopy of polymer-nanoparticle non-volatile memory devices
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89, s. 133510-
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Tidskriftsartikel (refereegranskat)abstract
- Nonvolatile resistive memory consisting of gold nanoparticles embedded in the conducting polymer poly(4-n-hexylphenyldiphenylamine) examined using admittance spectroscopy. The frequency dependence of the devices indicates space-charge-limited transport in the high-conductivity "on" state, as well as evidence for similar transport in the lower-conductivity "off" state. Furthermore, the larger dc capacitance of the on state indicates that a greater amount of filling of the midgap nanoparticle trap levels increases the overall device conductivity, leading to the memory effect.
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