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  • 2000-2004  (2)
  • 2002  (2)
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  • 2000-2004  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5411-5418 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have successfully fabricated superconducting nanobridges and grain-boundary junctions from epitaxial YBa2Cu3O7−δ thin films with thickness between 20 and 30 nm and width down to ∼100 nm. The patterning process turned out to severely deteriorate the transport properties resulting in structural damage, corrosion, and oxygen loss. The most crucial steps are the baking procedure used to cure the electron beam resist, the resist development, and the ion beam etching process. By optimizing these steps and applying a suitable post-treatment procedure a significant enhancement of the sample quality could be achieved. An ultraviolet light assisted oxygenation procedure after the patterning process enabled us to achieve superconducting transition temperatures between 80 and 87 K and critical current densities at 4.2 K up to 4×107 A cm−2 for the nanobridges and 5×103–2×105 A cm−2 for the grain boundary junctions. At 4.2 K junctions with width down to 100 nm corresponding to a junction area down to 2.3×10−3 μm2 showed superconductivity. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    Journal of neurochemistry 80 (2002), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Clinical studies have shown that estrogen deprivation through menopause is a risk factor in both the initiation and progression of Alzheimer's disease (AD) and that estrogen replacement therapy may be protective. One of the major pathological features in the human AD brain is the senile plaque, a proteinaceous structure composed mainly of heterogeneous peptides collectively known as A-beta (Aβ). In vitro studies have linked estrogen with Aβ modulation, suggesting that one-way that estrogen depletion at menopause may exacerbate the features of AD is through Aβ accumulation. To test this, two studies were performed on transgenic models of amyloidosis. Firstly, transgenic mice without detectable amyloid aggregates were subjected to ovariectomy and estradiol supplementation, and Aβ levels were assessed. Secondly, the effects of estrogen modulation were assessed in mice at an age when plaques would be forming initially. Overall, Aβ levels were higher in estrogen-deprived mice than intact mice, and this effect could be reversed through the administration of estradiol. These data suggest that, in vivo, estrogen depletion leads to the accumulation of Aβ in the CNS, which can be reversed through replacement of estradiol. These results provide evidence that post-menopausal estrogen depletion may be linked to an increased risk of AD through Aβ modulation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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