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  • Electronic Resource  (6)
  • Physics  (2)
  • carbon dioxide  (2)
  • Cs–Fe/SiO2  (1)
  • Immunohistochemistry  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Promoting effect of carbon dioxide on the dehydrogenation and aromatization of ethane over gallium‐loaded catalysts (2000)
    Springer
    Catalysis letters 64 (2000), S. 215-221 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1019047306179
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of support on the conversion of methane to synthesis gas over supported iridium catalysts (1998)
    Springer
    Catalysis letters 51 (1998), S. 163-167 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1019065824331
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  • 3
    Electronic Resource
    Electronic Resource
    Acrolein formation in the oxidation of ethane over silica catalysts supporting iron and cesium (1999)
    Springer
    Catalysis letters 63 (1999), S. 79-82 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1019044316231
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  • 4
    Electronic Resource
    Electronic Resource
    Dedifferentiated leiomyosarcoma of the intestinal tract: histological, ultrastructural and immunohistochemical examinations (1992)
    Springer
    Virchows Archiv 420 (1992), S. 313-320 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01600210
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  • 5
    Electronic Resource
    Electronic Resource
    Stereochemical regulation of polypropylenes prepared with various Ziegler-Natta catalysts (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 771-784 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 220-MHz proton magnetic resonance and infrared spectra of stereoregular polypropylenes polymerized with a number of Ziegler-Natta catalysts and isotactic polymers of low molecular weight obtained by thermal degradation of a highly isotactic polypropylene were measured in an attempt to obtain some information on the local regularity. The fraction of thermally degraded polymer soluble in diethyl ether shows stereorandomness (tactie sequence length is quite short), and the portion soluble in n-pentane has stereoblock character. The results so obtained provide strong evidence that racemic dyads of whole polymer consist of two models of racemic dyad isolated and racemic dyads in groups. The polymers prepared with vanadium catalyst systems show stereorandom character and these polymers have \documentclass{article}\pagestyle{empty}\begin{document}$\hbox{-\hskip-1pt-}\hskip-4pt({\rm CH}_2 \rlap{--} )$\end{document} groups formed by two propylene units in a tail-to-tail linkage. Syndiotactic polypropylene has head-to-head and tail-to-tail arrangements of two propylene units and this is the origin of randomness of syndiotacticity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120407
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  • 6
    Electronic Resource
    Electronic Resource
    220-MHz NMR spectra of acrylic monomer-2-substituted 1,3-diolefin alternating copolymers (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 2553-2563 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An investigation by 220-MHz NMR spectroscopy was carried out on the alternating copolymers of acrylic monomer with 2-substituted 1,3-diolefin. The chain structures were determined. The acrylic monomers used were methyl methacrylate (MMA), acrylonitrile (AN), and methacrylonitrile (MAN); isoprene (IP) and chloroprene (CLP) were the 1,3-diolefins. In the MAN-IP alternating copolymer, the 1-position methylene protons of IP showed an AB quartet peak, confirming the α-1 linkage structure. Similarly, in the MMA-CLP and AN-CLP copolymers, the 1-position methylene protons of CLP showed and AB quartet and an ABX pattern, respectively, confirming the α-1 linkage structure in both these cases also. The α-1 linkage structure was also revealed by the decoupling technique in the MAN-CLP alternating copolymer. The AN-IP and MMA-IP alternating copolymers also possess a bond between the α-position of the acrylic monomer and the 1-position of IP. The monomeric units in the alternating copolymers of acrylic monomers with 2-substituted 1,3-diolefins were generally linked at the α-position of acrylic monomer and the 1-position of 1,3-diolefin. On the other hand, in the Diels-Alder adducts of acrylic monomer with 2-substituted 1,3-diolefin, the reaction takes place between the α-position of acrylic monomer and the 4-position of 1,3-diolefin.The regioselectivity of the alternating copolymers and the Diels-Alder adducts is quite compatible with the expectations from molecular orbital theory.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.170141020
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