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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 6057-6059 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a technique to create very small semiconductor nanostructures, with sizes far beyond the limit of conventional optical lithography processes, by the use self-assembling diblock copolymers as nanolithographic masks. Quantum structures with very high aspect ratio of 1:10 were fabricated by dry etching. In a first step, so-called diblock copolymer micelles were generated in a toluene solution. These micelles were loaded by a noble-metal salt. After dipping a substrate into this solution, a monolayer of ordered micelles is generated, covering almost the complete surface. After treatment in a hydrogen plasma all of the organic components are removed and only crystalline metal clusters of (approximate)12 nm size remain. This metal cluster mask can be used directly in a chlorine dry etching process to etch cylinders in GaAs and its alloys of In and Al. It is also possible to etch through a quantum well layer underneath the surface in order to produce quantum dots. The resulting nanostructures were investigated by scanning force microscopy, by high resolution transmission electron microscopy, and also by low temperature photoluminescence spectroscopy. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2015-08-16
    Description: Perinatal exposures exert a profound influence on physiological function, including developmental processes vital for efficient pulmonary gas transfer throughout the lifespan. We extend the concept of developmental programming to chronic mountain sickness (CMS), a debilitating syndrome marked by polycythemia, ventilatory impairment, and pulmonary hypertension that affects ~10% of male high-altitude residents. We hypothesized that adverse perinatal oxygenation caused abnormalities of ventilatory and/or pulmonary vascular function that increased susceptibility to CMS in adulthood. Subjects were 67 male high-altitude (3,600–4,100 m) residents aged 18–25 yr with excessive erythrocytosis (EE, Hb concentration ≥18.3 g/dl), a preclinical form of CMS, and 66 controls identified from a community-based survey ( n = 981). EE subjects not only had higher Hb concentrations and erythrocyte counts, but also lower alveolar ventilation, impaired pulmonary diffusion capacity, higher systolic pulmonary artery pressure, lower pulmonary artery acceleration time, and more frequent right ventricular hypertrophy, than controls. Compared with controls, EE subjects were more often born to mothers experiencing hypertensive complications of pregnancy and hypoxia during the perinatal period, with each increasing the risk of developing EE (odds ratio = 5.25, P = 0.05 and odds ratio = 6.44, P = 0.04, respectively) after other factors known to influence EE status were taken into account. Adverse perinatal oxygenation is associated with increased susceptibility to EE accompanied by modest abnormalities of the pulmonary circulation that are independent of increased blood viscosity. The association between perinatal hypoxia and EE may be due to disrupted alveolarization and microvascular development, leading to impaired gas exchange and/or pulmonary hypertension.
    Print ISSN: 0363-6135
    Electronic ISSN: 1522-1539
    Topics: Medicine
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