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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 27 (1994), S. 67-78 
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; Cu/ZnO catalyst ; Cu-Zn alloy ; effect of reduction temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The behavior and role of ZnO in Cu/ZnO catalysts for the hydrogenations of CO and CO2 were studied using XRD, TEM coupled with EDX, TPD and FT-IR. As the reduction temperature increased, the specific activity for the hydrogenation of CO2 increased, whereas the activity for the hydrogenation of CO decreased. The EDX and XRD results definitely showed that ZnO x (x = 0–1) moieties migrate onto the Cu surface and dissolve into the Cu particle forming a Cu-Zn alloy when the Cu/ZnO catalysts were reduced at high temperatures above 600 K. The content of Zn dissolved in the Cu particles increased with reduction temperature and reached ∼ 18% at a reduction temperature of 723 K. The CO-TPD and FT-IR results suggested the presence of Cu+ sites formed in the vicinity of ZnO x on the Cu surface, where the Cu+ species were regarded as an active catalytic component for methanol synthesis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 31 (1995), S. 325-331 
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; copper catalyst ; role of ZnO ; XPS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Methanol synthesis by the hydrogenation of CO2 over Zn-deposited polycrystalline Cu was studied using surface science techniques. The Zn sub-monolayer was oxidized by the reaction mixture during the reaction at 523 K, leading to the formation of ZnO species. The kinetic results definitely showed that the ZnO species on the Cu surface promoted the catalytic activity of methanol formation, where the activity of Cu increased by a factor of 6 at the Zn coverage of 0.17. A volcano-shaped curve was obtained for the correlation between the Zn coverage and the catalytic activity, which was very similar to the correlation curve between the oxygen coverage and the specific activity for methanol formation previously obtained for the Cu powder catalysts. The role of ZnO in Cu/ZnO based catalysts was ascribed to the stabilization of Cu+ species by the ZnO moieties on the Cu surface.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; copper catalyst ; oxygen coverage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The coverage of oxygen formed on the surface of catalysts during methanol synthesis from CO2 has been measured for copper-based catalysts including various metal oxides using a method called reactive frontal chromatography (RFC). An excellent correlation between the specific activity for methanol synthesis and the oxygen coverage (θ) was obtained, where the activity increased linearly with oxygen coverage atθ〈0.16 and then decreased atθ〉0.18. The results strongly indicate that the support effect or addition of metal oxides revealed in methanol synthesis over copper catalysts is ascribed to the ratio of Cu+ to Cu0 on the surface of copper particles.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurology 216 (1977), S. 79-89 
    ISSN: 1432-1459
    Schlagwort(e): Normal muscle spindle ; Histochemistry ; Intrafusal fiber types ; Fusimotor endings ; Fusisensory endings
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wurden normale Skeletmuskelspindeln von Menschen histochemisch untersucht. 1. Histochemisch wurden vier Muskelfasertypen der intrafusalen Fasern — Bag I fiber, Bag II fiber, Chain I fiber und Chain II fiber — von ATPase-Aktivität klassifiziert. Bei der NADH-Tetrazolium-Reduktase wurden zwei Muskelfasertypen an intrafusalen Fasern — Bag I fiber und Bag II fiber — beobachtet. 2. Drei Typen der motorischen Endplatte — en plaque Endplatte, en grappe Endplatte und diffuse Endplatte — wurden an Muskelspindeln von Cholinesterase klassifiziert. 3. Zwei Typen der sensorischen Nervenenden — primär-sensorisches Nervenende und sekundärsensorisches Nervenende — wurden an Muskelspindeln mit NADH-Tetrazolium-Reduktase und elektronmiktroskopisch beobachtet.
    Notizen: Summary Normal muscle spindles of human skeletal muscle were studied histochemically. 1) Four histochemical types of intrafusal muscle fibers were classified by ATPase stain: Bag I fiber, Bag II fiber, Chain I fiber and Chain II fiber. Moreover, two types of nuclear bag fibers were classified by NADH Tetrazolium Reductase stain and PAS stain: Bag I fiber and Bag II fiber. 2) Three kinds of fusimotor endings were verified by the cholinesterase technic: en plaque, en grappe and diffuse endings. 3) Two kinds of fusisensory endings were verified by NADH TR stain and also electron-microscopically: primary and secondary sensory endings.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neurology 219 (1978), S. 261-271 
    ISSN: 1432-1459
    Schlagwort(e): Fusimotor endings ; Acetylcholinesterase ; Parkinsonism ; Motor neuron disease ; Myasthenia ; Muscle spindles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In Serienschnitten wurden die motorischen Endplatten der intrafusalen Muskelfasern in Muskelspindeln von Patienten mit Parkinsonismus, myatrophischer Lateralsklerose und Myasthenia gravis mittels Acetylcholinesterasereaktion untersucht. Beim Parkinsonismus erschienen die diffusen Endigungen, von welchen angenommen wird, daß sie die Endigungen des Gammafasersystemes darstellen, nennenswert verbreitert, während die en-plaque- und en-grappe-Endigungen atrophisch erschienen. In den Fällen von myatrophischer Lateralsklerose erwiesen sich en-plaque- und en-grappe-Endigungen, von welchen angenommen wird, daß sie zu den Betaneuronen und den dynamischen Gammafasern gehören, als ausgesprochen atrophisch. Die diffusen Endigungen allerdings waren normal. Bei Myasthenia gravis und dem myasthenischen Syndrom von Eaton-Lambert zeigten en-plaque- und engrappe-Endigungen Atrophien, während einzig die diffusen Endigungen ausgespart blieben. Es wird die Bedeutung dieser Veränderungen diskutiert.
    Notizen: Summary Pathological changes of the fusimotor endings in parkinsonism, motor neuron disease and myasthenia were examined by the acetylcholinesterase technic on serial sections. In parkinsonism, the diffuse endings, which are thought to be supplied by the static gamma nerve fibers, showed remarkable enlargement, while en plaque and en grappe endings were atrophic. In motor neuron disease, en plaque and en grappe endings, which are thought to be innervated by the beta nerve fibers and dynamic gamma nerve fibers respectively, revealed marked atrophy. However the diffuse endings were normal. In myasthenia gravis and myasthenic syndrome (Eaton-Lambert syndrome), en plaque and en grappe endings were atrophic, though only the diffuse endings were spared. The significance of these changes in the fusimotor endings is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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