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  • Electronic Resource  (4)
  • 1990-1994  (4)
  • Propranolol ester derivatives  (2)
  • Failuremechanisms  (1)
  • Flash X-rays  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Micromechanisms of failure in short-fiber-reinforced high-impact polystyrene under tensile loading (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 659-666 
    Details
    ISSN: 1435-1536
    Keywords: Failuremechanisms ; high-impactpolystyrene ; short-fiber-reinforcedthermoplastics ; rubberparticles ; craze-controlledcracking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Injection-molded, short-glass-fiber-reinforced high-impact polystyrene was investigated under uniaxial tension with special attention to the effects of fiber and rubber concentration on fracture behavior. According to a fracture morphology study performed by polarized optical and scanning electron microscopy, crazes were consecutively initiated from rubber-styrene composite particles and from fiber ends. The rubber particles exhibited an intra-particle failure mode which resulted from the failure manner of the matrix becoming of a more brittle character with increasing fiber fraction. Fibers were surrounded by neigh boring growing crazes. Failure at the fiber-matrix interfaces proceeded with an increase in the number of crazes. With increasing concentration of the fibers, crazing at rubber particles appeared to be suppressed and crazing occurred more preferentially at the fiber ends, which accelerated a macroscopic fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654042
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    Paper (German National Licenses)
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  • 2
    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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    Paper (German National Licenses)
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  • 3
    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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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Disk-cathode flash X-ray tube driven by a repetitive two-stage Marx pulser (1993)
    Springer
    Medical & biological engineering & computing 31 (1993), S. S37 
    Details
    ISSN: 1741-0444
    Keywords: Cold-cathode diode ; Disk cathode ; Flash X-rays ; Photon energy control ; Pulsed X-rays ; Tube current control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Fundamental studies of a repetitive flash X-ray generator using a diskcathode radiation tube are described. The high-voltage pulser employed a modified two-stage surge-Marx circuit. The two condensers in the pulser were charged from 40 to 60 kV, and the electric charges were discharged to the X-ray tube repetitively to generate flash X-rays. The total capacity during the main discharge was 425 pF, and the maximum output voltage from the pulser was about 1·9 times the charged voltage. The flash X-ray tube of the demountable-diode type and was composed of a rodshaped anode tip made of tungsten, a disk cathode made of graphite and a tube body made of polymethylmethacrylate. The peak tube voltage was primarily determined by the anode-cathode (A-C) space, and the peak tube current was less than 0·5 kA. Thus the maximum photon energy could be easily controlled by varying the A-C space, and the tube current roughly increased according to increases in the charged voltage. The pulse width ranged from 40 to 100 ns, and the X-ray intensity was less than 1·1 μC kg−1 at 0·5 m per pulse. The repetition rate was less than 50 Hz, and the effective focal spot size was equivalent to the anode diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446648
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    Paper (German National Licenses)
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