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  • 1985-1989  (5)
  • 1965-1969
  • 1985  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Cell K activity in frog skin in the presence and absence of cell current (1985)
    Springer
    The journal of membrane biology 85 (1985), S. 143-158 
    Details
    ISSN: 1432-1424
    Keywords: frog skin ; anions and sodium transport ; membrane potential ; K activity ; pump current ; constant current source
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Cell K activity,a k, was measured in the short-circuited frog skin by simultaneous cell punctures from the apical surface with open-tip and K-selective microelectrodes. Strict criteria for acceptance of impalements included constancy of the open-tip microelectrode resistance, agreement within 3% of the fractional apical voltage measured with open-tip and K-selective microelectrodes, and constancy of the differential voltage recorded between the open-tip and the K microelectrodes 30–60 sec after application of amiloride or substitution of apical Na. Skins were bathed on the serosal surface with NaCl Ringer and, to reduce paracellular Cl conductance and effects of amiloride on paracellular conductance, with NaNO3 Ringer on the apical surface. Under control conditionsa k r was nearly constant among skins (mean±SD=92±8mM, 14 skins) in spite of a wide range of cellular currents (5 to 70 μA/cm2). Cell current (and transcellular Na transport) was inhibited by either apical addition of amiloride or substitution of Na by other cations. Although in some experiments the expected small increase ina k r after inhibition of cell current was observed, on the average the change was not significant (98±11mM after amiloride, 101±12mM after Na substitution), even 30 min after the inhibition of cell current. The membrane potential, which in the control state ranged from −42 to −77 mV, hyperpolarized after inhibition of cell current, initially to −109±5mV, then depolarizing to a stable value (−88±5mV) after 15–25 min. At this time K was above equilibrium (E k=98±2mV), indicating that the active pump mechanism is still operating after inhibition of transcellular Na transport. The measurement ofa k r permitted the calculation of the passive K current and pump current under control conditions. assuming a “constant current source” with almost all of the basolateral conductance attributable to K. We found a significant correlation between pump current and cell current with a slope of 0.31, indicating that about one-third of the cell current is carried by the pump, i.e., a pump stoichiometry of 3Na/2K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871267
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Time-dependent phenomena in voltage-clamped epithelia (1985)
    Springer
    The journal of membrane biology 87 (1985), S. 173-176 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870663
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Disturbance of plasmalemmal astrocytic assemblies in focal and selective cerebral ischemia (1985)
    Springer
    Anatomy and embryology 172 (1985), S. 171-175 
    Details
    ISSN: 1432-0568
    Keywords: Cat caudate nucleus ; Ischemia ; Plasmalemmal glial assemblies ; Cytotoxic edema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Selective cerebral ischemia was induced in the caudate nucleus of seven normothermic anesthetized cats through transorbital clamping of the anterolateral penetrating lenticulostriated arteries. The plasmalemma of astrocytic foot processes has been studied with the freeze-fracture technique and conventional electron microscopy 10, 15 and 30 min after ischemia. After 15 min of circulatory arrest, assemblies of intramembrane particles (IMPs) disappear in some areas of astroglial perivascular plasmalemma in the ischemic caudate nucleus. Interastrocytic gap junctions do not change significantly. 30 min after ischemia, the pericapillary astroglial end foot is expanded and organelles are greatly perturbed (cytotoxic edema). Although the function of astrocytic intramembrane particle assemblies is unclear, it is postulated that the disappearance of this membrane specialization may play a role in the pathophysiology of cytotoxic astroglial edema.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319599
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Study of some aspects of the reactivity of La2O3 with CO2 and H2O (1985)
    Springer
    Journal of materials science 20 (1985), S. 537-541 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The behaviour of three different samples of La2O3 on exposure to atmoshperic CO2 and H2O and the influence of the origin is discussed. The thermal evolution of the samples, stabilized in air for months or even years, has been studied by TG, TPD, IR spectroscopy and X-ray diffraction. BET surface areas of the samples were determined from the corresponding nitrogen adsorption isotherms at 77 K. In all three samples, hydration and carbonation occur in bulk. In accordance with our results, lanthana samples stabilized in air would consist of lanthanum hydroxide, La(OH)3, partially carbonated, La2(OH)6−3x (CO3) x ,(x⪝1). When hexagonal phases of La2O3, obtained by calcining, at 1130 K, the samples stabilized in air were re-exposed, hydration and carbonation levels similar to those observed in the stabilized samples were reached after less than 24 h. Some lanthana samples were soaked in water, at 298 K, and then dried at 380 K. In this way, the evolution of the oxide when treated under similar conditions to those used in both impregnation and ion exchange techniques for preparation of supported metal phases, could be investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01026524
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Block diagonal scaling for iterative methods in thermal simulation (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Communications in Applied Numerical Methods 1 (1985), S. 263-267 
    Details
    ISSN: 0748-8025
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Linear equations arising from reservoir simulation are closely coupled at the local-cell level, and the variables and equations tend to be poorly equilibrated. Scaling by the inverse of the diagonal block has an equilibrating effect. It usually improves the condition of the matrix for solution by linear iteration. The effects of block diagonal scaling are illustrated for a thermal reservoir simulator, where the original matrix may be indefinite. These results illustrate that for difficult problems block diagonal scaling can significantly enhance the convergence rate of the iterative method. It is also illustrated that preconditioned generated by block incomplete LU decomposition (ILU) and block symmetric Gauss Seidel (BSGS) methods are effective preconditioned for use in thermal simulation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1630010602
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    Paper (German National Licenses)
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