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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 147 (1995), S. 1-6 
    ISSN: 1432-1424
    Keywords: Na channel ; Batrachotoxin ; Bilayers ; Surface potential ; Energy profile ; Divalent cation block
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Internal application of millimolar concentrations of calcium to batrachotoxin (BTX)-activated rat skeletal muscle sodium channels, bathed symmetrically in 200 mm NaCl, causes a reduction in apparent singlechannel amplitude without visibly increasing noise at a bandwidth of 50 Hz. A greater calcium-induced reduction occurred upon removal of external sodium ions. Internal calcium acted similarly in high ionic strength solutions (3m NaCl), where surface charges are effectively screened, suggesting that calcium acts, in part, by binding within the pore and occluding the conducting pathway. In low ionic strength solutions (20 mm NaCl), internal addition of N-Methyl-Glucamine (NMG) ions decreased the single channel amplitude consistent with screening of negative surface charges. An accurate description of the dose dependence of calcium inhibition, using either a simple blocking model, or rate theory calculations of ion permeation and block, also required surface charge screening. Hence, our data support the view that sodium current inhibition by internal calcium arises from a combination of both open-channel block and surface charge effects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 42-58 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The prediction of polymer/polymer miscibility is addressed using analog calorimetry and molecular modeling. For each polymer, an analog compound representing one or two repeat units was chosen. Heat-of-mixing was measured for liquid mixtures of analog compounds and then used in a binary interaction model to predict polymer miscibility. Specifically, we have measured exothermic heats-of-mixing for 4-ethyl phenol, an analog of poly(vinly phenol), with several analogs containing ether, ester, or ketone functional groups. The exothermic heat-of-mixing results are consistent with the observed miscibility of poly(vinyl phenol) with polymers containing these functional groups. Using interaction parametes derived from the analog calorimetry in the binary interaction model or using premixes of 4-ethyl phenol in ethyl benzene, we correctly predict the magnitude and relative order of the fraction of vinyl phenol units in copolymers with styrene required for miscibility with poly(methyl methacrylate), polyacetal, and a polyketone. the miscibility trends for poly(vinyl phenol) blends predicted from analog calorimetry and the binary interaction model are in reasonable agreement with those predicted from the association model of Painter and Coleman, despite the different bases of the two approaches. We have used molecular modeling to complement the analog calorimetry and to assess steric effects on hydrogen-bonding ability for models of poly(n-butyl acrylate) and poly(t-butyl acrylate) with phenol. The modeling results suggest that, in some cases, steric effects and the three-dimensional structure of the polymer can significantly influence the hydrogen-bonding ability of polymers relative to their analogs.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2006-03-27
    Description: Mariner 9 observations of time variable Martian dark areas and semi-tone areas are commonly resolved into streaks and splotches caused by sand storm particles. Bright streaks are formed by the smaller particles and require exceptionally high velocities for their formation as compared with the more easily saltated larger particles in dark streak areas.
    Keywords: SPACE SCIENCES
    Type: JPL Mariner Mars 1971 Proj., Vol. 4; p 179-217
    Format: text
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  • 4
    Publication Date: 2011-08-16
    Description: Systematic Mariner 9 monitoring of the space and time distribution of Martian bright and dark markings, the streaks and splotches, indicates a range of global correlations. The time-variable classical dark markings owe their configurations and variability to their constituent streaks and splotches, produced by windblown dust. Streaks and splotches are consistent wind direction indicators. Correlation of global streak patterns with general circulation models shows that velocities of about 50 to 90 m/sec above the boundary layer are necessary to initiate grain motion on the surface and to produce streaks and splotches. Detailed examples of changes in Syrtis Major, Lunae Palus, and Promethei Sinus are generally consistent with removal of bright sand and dust and uncovering of darker underlying material as the active agent in such changes, although dark mobile material probably also exists on Mars. The generation of streaks and the progressive albedo changes observed require only threshold velocities of about 2 m/sec for about 1 day at the grain surface.
    Keywords: SPACE SCIENCES
    Type: Journal of Geophysical Research; 78; July 10
    Format: text
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  • 5
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    In:  Other Sources
    Publication Date: 2019-06-27
    Description: We examine a propagating wave interpretation of the temperature profile features observed in the Jovian upper atmosphere by Veverka et al. (1974). Inertia-gravity waves with frequencies on the order of .003 per sec are consistent with the data. If the interpretation is correct, and if the waves carry energy upward, it implies (1) that there is excitation of such waves at lower levels, (2) that eddy diffusivities on the order of 1,000,000 sq cm/sec are probably generated by the waves, and (3) that the energy carried by waves is important to the upper atmospheric heat balance.
    Keywords: SPACE SCIENCES
    Type: Journal of the Atmospheric Sciences; 31; Sept
    Format: text
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