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  • Digitale Medien  (3)
  • sulfated zirconia  (2)
  • 123I-IMP SPECT  (1)
  • 1
    ISSN: 1572-879X
    Schlagwort(e): oxidative dehydrogenation ; ethane ; sulfated zirconia ; lithium chloride
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The oxidative dehydrogenation of ethane over sulfated-zirconia-supported lithium chloride catalysts has been systematically investigated. The optimal experimental parameters were obtained. It is found that sulfation of zirconia increases the catalytic activity. 2–3.5 wt% lithium chloride on sulfated zirconia catalysts exhibit high catalytic activity for oxidative dehydrogenation of ethane, with particularly high activity for ethene production. 70% selectivity to ethene at 98% ethane conversion, giving 68% ethene yield, is achieved over 3.5 wt% LiCl/SZ at 650°C.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1572-879X
    Schlagwort(e): sulfated zirconia ; lithium chloride ; metal oxides ; ethane ; oxidative dehydrogenation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effects of some transition‐ and lanthanide‐metal oxides in LiCl/sulfated‐zirconia (SZ) catalysts on catalytic behavior in the oxidative dehydrogenation of ethane were investigated. It is found that modification of LiCl/SZ by metal oxides significantly improves the catalytic activity and ethene yield. Among those additives, Ni and Nd oxides show the best promoting effect in terms of ethane conversion and ethene yield. 93% ethane conversion with 83% selectivity to ethene has been achieved over the Nd2O3–LiCl/SZ catalyst at 650°C. In addition, those oxide‐promoted LiCl/SZ catalysts are also found to exhibit a longer stability in catalytic performance. Metal‐oxide additives change the chemical structure and surface redox properties, which accounts for the enhancement of activity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0942-0940
    Schlagwort(e): Dementia ; extracranial-intracranial bypass ; 123I-IMP SPECT ; long-term follow-up
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The long-term effect of extra-intracranial arterial bypass on cerebral circulation was examined. Cortical blood flow and cognitive ability were evaluated pre and up to 3 years post-bypass in a 58-years-old man with severe carotid occlusive lesions, who presented with 3 transient cerebral ischaemic attacks which resulted in mental deterioration over 3 years. Regional cerebral blood flow (rCBF) was evaluated pre- and up to 33 months post-bypass by123Iodine N-isopropyl-p-iodoamphetamine (IMP) single-photon emission CT (SPECT). Mental abilities were evaluated before and up to 33 months after surgery by the Hasegawa's dementia rating scale (HDRS). Pre-operatively, cerebral angiography showed left carotid siphon occlusion and hypoplastic stenosis of left anterior cerebral artery with collaterals from the anterior communicating artery. CT and MRI showed left temporo-parietal borderzone infarction and an enhanced T1 lesion by gadolinium-DTPA at left periventriculum. rCBF showed extensive hypoperfusion in left anterior-parieto-temporal-cortex. HDRS scores deteriorated apparently on days 3, 5, which recovered gradually on days 8, 10, 75 after onset of mental deterioration. A bypass was performed 4 months after onset. rCBF showed gradual recovery in the left anterior-parietal cortex up to 33 months after bypass. Semiquantitative rCBF showed gradual decreases of regional asymmetry after the bypass. HDRS scores returned to their maximum up to 37 months after onset. Three-year follow-up shows improved cortical rCBF and cognition after the bypass.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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