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  • 1975-1979  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Use of lattice imaging in the electron microscope in the structure determination of the 126R polytype of SiC (1978)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 34 (1978), S. 116-120 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Lattice fringes corresponding to (00.3) spacings of the 126R polytype of SiC have been obtained in the electron microscope. A number of 10.l reflections were allowed to pass through the objective aperture to obtain the lattice fringes showing a periodicity of ̃105 Å (one third of the c parameter of the hexagonal cell) and each unit-cell block is subdivided into smaller blocks corresponding to the spacings of 6H, 15R, 21R etc. The stacking sequence of these blocks has been used to work out the detailed structure of the 126R polytype. It has been suggested that the lattice resolution technique in conjunction with X-ray diffraction is likely to prove a useful method for determining difficult polytypic structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739478000200
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray diffraction and transmission electron microscopy study of extremely large-period polytypes in SiC (1977)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 276-279 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Extremely large-period polytypes in SiC have been investigated by single-crystal X-ray diffraction and direct lattice imaging by electron microscopy, which has been found to be a more suitable technique for studying structures of extremely large periodicities. Some crystals giving rise to a diffuse streaking along h0.l reciprocal lattice rows when studied by X-ray diffraction, showed the presence of extremely long- period polytypes when investigated by electron microscopy. The c periodicity of such SiC structures (having periodicities of more than 1000 Å) has been determined by this technique and the super-period block spacing is found to contain block spacings of 6H, 15R, 4H and 21R polytypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739477000692
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Muscarinic inhibition of potassium-induced noradrenaline release and its dependence on the calcium concentration (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 291 (1975), S. 1-15 
    Details
    ISSN: 1432-1912
    Keywords: Heart ; Noradrenaline release ; Potassium ; Calcium ; Methacholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Noradrenaline release from the isolated rabbit heart was evoked by perfusion with a medium containing 135 mM potassium and 17 mM sodium ions (high K+-low Na+). 2. The noradrenaline output in response to high K+-low Na+ was dose-dependently decreased by methacholine (0.625–320 μM) and this effect was reserved by atropine 1.44 μM. 3. Lowering the calcium concentration of high K+-low Na+ from 1.8–0.1125 mM decreased the noradrenaline output by 85%. The effect of methacholine, expressed as % inhibition of noradrenaline release, was potentiated by lowering of the calcium concentration. 4. Both at normal and lowered calcium concentrations the inhibitory action of methacholine was larger from 0–5 than from 5–10 min after perfusion with high K+-low Na+. 5. Perfusion of hearts with media containing high K+-high Na+ or normal K+-low Na+ caused noradrenaline outputs somewhat smaller than those after high K+-low Na+. The release from 0–5 min was both calcium-dependent and inhibited by methacholine. 6. High K+ and/or low Na+ solutions caused an increase in coronary perfusion pressure which was little affected by the noradrenaline released simultaneously. 7. It is concluded that activation of muscarine receptors at the terminal adrenergic fibre decreases the availability of calcium for transmitter release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00510816
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    Paper (German National Licenses)
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