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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 43 (1987), S. 197-201 
    ISSN: 1432-0649
    Keywords: 81.60 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract X-ray photoemission spectroscopy (XPS) has been used to study the surface reaction of Zn3P2 single crystals. The spectra of crystals exposed to H2, O2, CO2, O2+H2O or CO2+H2O during a four week period were compared to the spectra of as-grown or in UHV scraped samples. For samples contaminated with the wet gases O2+H2O and CO2+H2O additional phosphorus core levels together with a shift of the zinc core levels were observed. For crystals exposed to atmosphere during several months no phosphorus could be detected on the gasgrown surface, whereas the stochiometry of Zn3P2 was maintained within the bulk. Crystals with scraped surfaces showed no moisture sensitivity. No surface contamination was also detected for Zn3P2 crystals deposited with up to 1000 L H2O or exposed to atmosphere during 30 min.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6792
    Keywords: Epilepsy ; Brain activity mapping ; Single photon emission computerized tomography (SPECT) ; Hexa-methyl-propylene-amine-oxime (HMPAO) ; Regional cerebral blood flow (rCBF) ; Ictal and interictal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-eight normal volunteers and 74 seizure patients were investigated with hexa-methyl-propylene-amine-oxime (HMPAO) brain single photon emission computed tomography (SPECT). Fifty-four patients suffered from partial seizures and 20 patients had generalized seizures. Indices describing regional tracer distribution (RIs) were calculated in all investigated subjects. Regions whose RI exceeded the mean normal RI +/-3 SD were defined as abnormally perfused. In normals a significant interhemispheric asymmetry of HMPAO deposition was found, with higher RI values in the right frontal, parietal, temporal and occipital regions. In 59.3% of partial seizure patients abnormal RIs were found. Low RIs were detected predominantly in the frontal and temporal cortex, while elevated RIs were observed predominantly in the anterior basal ganglia. Only in 20% of the cases with generalized seizures, abnormal RIs were found. In one patient an ictal and 3 follow-up SPECT studies were obtained. Here SPECT results indicated transient rCBF changes between the ictal and seizure free state. EEG and SPECT foci were ipsilaterally located in 69.2% of the partial seizure cases. The results indicate that HMPAO brain SPECT is valuable for the detection of rCBF abnormalities in seizure patients and that patients with partial seizures have mostly several abnormally perfused areas in their brains.
    Type of Medium: Electronic Resource
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