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  • 1
    ISSN: 1432-0533
    Keywords: Status epilepticus ; Substantia nigra ; Pathology ; Convulsions ; Convulsants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light microscopic and ultrastructural changes of substantia nigra were studied in paralyzed ventilated rats with status epilepticus induced by mercaptopropionic acid. Some rats were killed at the end of seizure activity and others were examined in varying intervals after the arrest of seizure. The earliest changes were reduction in the size of the neuronal nuclei and chromatin clumping followed by simultaneous distention of axons and dendrites. There was also enlargement of the neuronal perikarya associated with microvacuolation. This neuronal microvacuolation corresponded ultrastructurally to swollen mitochondria with disrupted cristae. These changes were followed by progressive neuronal shrinkage and astrocytic swelling. The swollen astrocytic processes together with swollen neurites gave a spongy appearance to the involved area. The lesion thereafter progressively enlarged and evolved into an area of frank necrosis containing abundant macrophages. This lesion is morphologically different from that produced in cortex and hippocampus by seizure activity or due to the direct effect of excitotoxins. The significance of substantia nigra pars reticularis changes and their pathogenesis are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1630-1632 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique to measure ozone fluxes of 1014–1016 cm−2 s−1 using a thin silver film deposited on a quartz-crystal deposition-rate monitor is described. The technique involves measuring the rate of mass increase of the silver film due to oxidation when it is first exposed to ozone. Ozone is found to be an extremely efficient oxidant for silver at room temperature. By establishing an independent measure of the incident ozone flux the product of our ozone purity and intrinsic detection efficiency has been determined to be 26±5%.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superconducting thin films of Bi-Sr-Ca-Cu-oxides have been reproducibly prepared by reactive magnetically enhanced triode sputtering using three separate metal targets (Sr, Ca, and Cu-Bi). Oxygen was introduced directly at the substrates during film growth. The films were deposited on ambient temperature substrates [Al2O3, SrTiO3, and yttria-stabilized zirconia (YSZ)] and had thicknesses of 0.5–1.5 μm. After deposition, the films were annealed at 850–900 °C in flowing oxygen. The electrical resistance of the best films on YSZ decreased approximately linearly with temperature until the onset of superconductivity at about 85 K. Zero resistance was achieved by 74 K. Critical current densities in excess of 5×105 A/cm2 at 4.2 K were also obtained. X-ray diffraction demonstrated that the best films were nearly single phase (Bi2Sr2Ca1Cu2O8+x) and textured with the c axis perpendicular to the substrate. The effect of composition and annealing on our results is discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1493-1495 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly oriented Bi-Sr-Ca-Cu-oxide thin films with Tc≥100 K and large (10–20 μm) grains were used to produce thin-film dc superconducting quantum interference devices (SQUIDs). The best SQUID, which operated up to 75 K, had an inside loop diameter of ∼18 μm and an estimated loop inductance of 30 pH. The device was patterned by standard photolithography and had weak links that were likely due to existing grain boundaries around the loop. The effective loop area, calculated from the period of the SQUID modulation, is roughly consistent with the geometrical area of the SQUID loop. Significant hysteresis was observed in the flux-voltage characteristic which depended on the amplitude of the magnetic field sweep. The 1/f noise levels measured at 100 Hz in this device gave a flux noise Sφ of 1.0×10−8 Φ20/Hz at 4.8 K and 2.3×10−7 Φ20/Hz at 60 K. The detailed noise measurements which we report for this SQUID are the first for any Bi-Sr-Ca-Cu-oxide based SQUID.
    Type of Medium: Electronic Resource
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