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  • 1
    ISSN: 1432-2307
    Keywords: Dedifferentiated leiomyosarcoma ; Intestinal tract ; Dedifferentiated element ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six cases of dedifferentiated leiomyosarcoma of the small and large bowel are presented with histological, ultrastructural and immunohistochemical examination. One case arose in the jejunum, two in the ileum, and the other three in the large intestine. The tumours were submucosal in four cases with large areas of ulceration; two were polypoid. Four tumours showed typical leiomyosarcomatous appearance with dedifferentiated components and two were typical leiomyosarcomas at the primary site with differentiated components only in metastatic foci. By immunohistochemistry, typical leiomyosarcomatous areas showed a positive reaction for muscle-specific actin (MSA), MB1, MB2 and myosin. In contrast, desmin-positive cells were scattered throughout the tumour or were not present. Tumour cells in dedifferentiated components were positive for alpha-1-antitrypsin and alpha-1-antichymotrypsin in all cases but one; neuron specific enolase, MB1, MB2 and myosin were positive with variety. MSA was faintly positive in only a few tumour cells of two cases and desmin was not detected in any of the cases studied. Ultrastructurally, tumour cells in typical leiomyosarcomatous areas demonstrated evident smooth muscle features, although in dedifferentiated areas they lacked such features except in one case. Our results indicate that dedifferentiated elements may derive from ordinary leiomyosarcoma and loose muscle features due to dedifferentiation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-879X
    Keywords: gallium oxide ; titanium oxide ; carbon dioxide ; oxidative dehydrogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ga2O3 and Ga2O3/TiO2 catalysts were found to be effective agents for the dehydrogenation of ethane to ethene in the presence of carbon dioxide at 650 °C. The activity of the Ga2O3 and Ga2O3/TiO2 catalysts in the presence of CO2 was 2–4 times higher than that without CO2. Ethene yields reached ca. 20–25% and selectivity was ca. 70–90% at 650°C in the 17% ethane and 83% CO2 feed at an SV of 9,000 ml/(g‐cat h). The presence of CO2 markedly promoted dehydrogenation of ethane over Ga2O3 and Ga2O3/TiO2 catalysts. Furthermore, the promoting effect of CO2 on the aromatization of ethane and ethene over a Ga2O3+H/ZSM‐5 catalyst was also observed above 650 °C. Aromatics yields were higher than those without CO2.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-879X
    Keywords: methane ; partial oxidation ; carbon dioxide ; reforming ; iridium ; titania ; synthesis gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A partial oxidation of methane was carried out using iridium catalysts supported on several metal oxides. The productivity of the synthesis gas from methane was strongly affected by the choice of support oxides for the catalysts. The synthesis gas production proceeded basically via a two-step reaction consisting of methane combustion to give H2O and CO2, followed by the reforming of methane from CO2 and steam. Although the combustion and the reforming of methane from steam did not depend upon the catalyst support, a large variation in the catalytic activity for the reforming of methane from CO2 was observed over Ir catalysts with different supports. The support activity order in the reforming of methane from CO2 with iridium catalysts was as follows: TiO2≧ZrO2≧Y2O3〉La2O3〉MgO≧Al2O3〉SiO2. The same order was observed in the synthesis gas production from the partial oxidation of methane.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-879X
    Keywords: ethane selective oxidation ; acrolein ; Cs–Fe/SiO2 ; aldol condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A significant yield of aldehydes was obtained by the partial oxidation of ethane over alkali‐modified Fe/SiO2 catalysts at 475°C (〈2% in the case of Cs–Fe/SiO2). Not only acetaldehyde and formaldehyde but also acrolein were produced in the present system. There are no reports regarding the catalysts for the direct acrolein formation from partial oxidation of ethane. Such significant promoting effect of alkali‐modified Fe/SiO2 catalysts in the partial oxidation of hydrocarbons has never been observed. Aldol‐type condensation for formation of acrolein could occur in the partial oxidation of ethane over alkali‐modified Fe/SiO2 catalysts.
    Type of Medium: Electronic Resource
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