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  • 1
    Electronic Resource
    Electronic Resource
    Retention, enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an alpha1-acid glycoprotein-bonded column (1992)
    Springer
    Chromatographia 33 (1992), S. 127-132 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Alpha 1-acid glycoprotein-bonded column ; Propranolol ; Propranolol ester derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an α1-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02275892
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  • 2
    Electronic Resource
    Electronic Resource
    Chiral separation of propranolol and its ester derivatives on an ovomucoid-bonded silica: Influence of pH, ionic strength and organic modifier on retention, enantioselectivity and enantiomeric elution order (1990)
    Springer
    Chromatographia 29 (1990), S. 587-592 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ovomucoid-bonded silica ; Chiral separation ; Propranolol ; Propranolol ester derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention, enantioselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propyl,-butyl and-valeryl PP) on an ovomucoid-bonded silica column have been investigated with respect to pH, ionic strength and organic modifier. For these cationic solutes, an increase in the organic modifier content and/or a decrease in the pH result in a decreased retention of both enantiomers. Enantioselectivity of the ester derivatives was higher than of underivated PP. The enantiomeric elution order was (S)/(R) for PP and (R)/(S) for the four ester derivatives, when ethanol or 2-propanol was used as the organic modifier. When methanol or acetonitrile was used as the organic modifier, inversion of the enantiomeric elution order was observed for O-valeryl PP with the use of methanol and for PP and O-propyl PP with acetonitrile. These results suggest that at least two chiral binding- or recognitionsites are present in a protein molecule and/or conformational changes occur in the chiral binding- or recognition-site(s) of the protein molecule bonded to a silica matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261228
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  • 3
    Electronic Resource
    Electronic Resource
    Cluster-size dependence of alloying behavior in gold clusters (1994)
    Springer
    The European physical journal 31 (1994), S. 131-134 
    Details
    ISSN: 1434-6079
    Keywords: 61.16.Di ; 36.40.+d ; 66.30.−h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cluster-size dependence of alloying behavior in nm-sized atom clusters has been studied by transmission electron microscopy, using clusters in the Au-Cu system. It was revealed that occurrence of rapid spontaneous alloying becomes more difficult with increasing cluster size. In gold clusters of approximately 4 nm in the mean size, a rapid dissolution of copper atoms took place and homogeneously mixed Au-Cu alloy clusters were formed. In gold clusters of approximately 10 nm in the mean size, rapid alloying of copper took place only at a shell-shaped region beneath the free surface of individual clusters and pure gold was retained at the central region of clusters. In gold clusters of approximately 30 nm in the mean size, no rapid alloying of copper was induced. The ease with which spontaneous alloying takes place is discussed in terms of the lattice softening in atom clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426588
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  • 4
    Electronic Resource
    Electronic Resource
    Structure of nm-sized InSb clusters formed by spontaneous alloying (1994)
    Springer
    The European physical journal 31 (1994), S. 209-212 
    Details
    ISSN: 1434-6079
    Keywords: 61.16.Di ; 36.40. + d ; 66.30. − h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The alloying behavior of antimony atoms into nm-sized indium clusters has been studied in situ by TEM. When antimony atoms are vapor-deposited onto nm-sized indium clusters, a rapid dissolution of antimony atoms into indium clusters takes place and as a result InSb compound clusters are successfully formed. Such spontaneous alloying occurs even at ambient temperature. InSb clusters thus formed have the wurtzite structure. When these InSb clusters are annealed at 533 K, their structure changes into the sphalerite structure, which is the structure of the equilibrium phase of the bulk In50Sb50. The appearance of wurtzite-type InSb by spontaneous alloying is discussed in terms of ionicity of bonds in InSb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437838
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