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  • 1
    Electronic Resource
    Electronic Resource
    State and distribution of potassium and sodium ions in frog skeletal muscle (1974)
    Springer
    The journal of membrane biology 15 (1974), S. 331-362 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A modified method for constructing cation-selective glass membrane microelectrodes is described. The method permits routine fabrication of electrodes with tip diameters less than 1 μ and exposed tip lengths of 2 to 5 μ. These electrodes had tip resistances in the range 107 to 109 ohms and gave stable and reproducible potentials in standard NaCl and KCl solutions. Potentials were unaffected by pH in the range 6 to 8 and satisfactory calibration curves were obtained over the temperature range 15 to 25°C. Pairs of electrodes with different K−Na selectivity coefficients were used to measure K+ and Na+ activities in frog sartorius fibers. In fibers containing normal amounts of these ions, Na+ activitywas much less than would be predicted from chemical analysis of the muscles, assuming that all the apparent muscle Na+ is present in an osmotically active form in the myoplasm. Possible origins of this discrepancy are discussed. Following a 48-hr soak at 5°C in a K-free medium, the apparent Na+ concentration and activity of the fibers both increased and the K+ concentration strongly suggests the existence in normal fibers of at least two intrafiber K+ compartments, both of which exchange with external Na+ but only one of which is detectible by a microelectrode located in the myoplasm. Ca++ appears to exert a strong regulatory effect on Na+−K+ exchange between these compartments and the external medium and on the distribution of intrafiber Na+ and K+ between these compartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870094
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  • 2
    Electronic Resource
    Electronic Resource
    KCl cotransport: A mechanism for basolateral chloride exit inNecturus gallbladder (1983)
    Springer
    The journal of membrane biology 76 (1983), S. 173-182 
    Details
    ISSN: 1432-1424
    Keywords: transcellular chloride transport ; intracellular chloride activity ; intracellular potassium activity ; K+ chemical potential ; Cl− chemical potential ; chloride permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary K+ and Cl−-selective double-barreled microelectrodes were used to study the effect of changes in external K+ concentration on intracellular Cl− activity (a Cl i ) in epithelial cells ofNecturus gallbladder. Decreasing the K+ concentration simultaneously in both bathing solutions produced a decrease ina Cl i . Steady-state values ofa Cl i were related to the values of the chamical potential gradient for K+ (ΔμK) across either the apical or the basolateral cell membrane. A similar dependence betweena Cl i and ΔμK appeared when the K+ concentration was changed in the serosal solution only. This indicates thata Cl i depends on ΔμK across the basolateral membrane.a Cl i was virtually independent of the membrane potential. This supports the idea that both the mucosal and the basolateral membranes ofNecturus gallbladder cells have very low passive permeabilities to Cl−. These results indicate that the exit of Cl− fromNecturus gallbladder cells is driven by ΔμK across the basolateral membrane, and suggest that a KCl electroneutral coupled mechanism in this membrane plays an important role in transcellular Cl− transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02000617
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  • 3
    Electronic Resource
    Electronic Resource
    Burst magnetostriction in Tb0.3Dy0.7Fe1.9 (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3548-3554 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetostriction and magnetic induction calculated by a continuous, anisotropic, anhysteric, magnetization model are compared with magnetostriction and magnetic induction measurements on burst and nonburst magnetostrictive Tb0.3Dy0.7Fe1.9 twinned single crystal rods. The model shows that the magnetostriction and permeability suppression occurring at low applied field is the result of the rotation, and subsequent capture, of initial field antiparallel magnetization into field transverse [111¯] or [1¯1¯1] local magnetoelastic energy minima. The model further shows that the interval of high magnetostriction applied field derivative, dλ/dH, characteristic of burst magnetostrictive material, is the result of the rotation of field transverse [111¯] or [1¯1¯1] oriented magnetization into the [111] near field magnetocrystalline minima. The occurance of burst magnetostriction is therefore contingent on obtaining sufficient magnetocrystalline anisotropy and sufficiently tight magnetization energy distribution in experimental Tb0.3Dy0.7Fe1.9 twinned single crystal rods so as to minimize the applied field interval over which this magnetization rotation process occurs. A final analysis shows that the present model is able to correctly approximate the applied field dependence of the burst magnetostriction response and the applied field dependence of the simultaneous magnetostriction and permeability suppression with a single set of parameters for a range of constant [112] applied compressive stresses. The model additionally exhibits approximately correct saturation magnetostrictions for a range of experimentally applied compressive stresses. However, the model fails to match the experimental behavior above a simultaneous dλ/dH, permeability and field hysteresis transition, located approximately 1000 microstrain from the saturation magnetostriction. The experimental transition clearly indicates a change in magnetization mechanism not accommodated by the present model. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364992
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  • 4
    Electronic Resource
    Electronic Resource
    Nonlinear behavior of magnetostrictive particle actuated composite materials (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3027-3031 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new theory is presented for the nonlinear multiaxial magnetoelastic behavior of magnetostrictive particle actuated composite materials. The analysis assumes a uniform external magnetic field is operating on a large number of well-distributed, crystallographically and shape parallel ellipsoidal magnetostrictive particles encased in an elastic, nonmagnetic composite matrix. The aspect ratio of the particulates may vary between 1 and infinity and the volume fraction of the particulates may vary between zero and one. Comparisons between experimental and model magnetostriction results show that the model is able to provide a quantitatively correct dependence on particulate volume fraction and longitudinal stress and quantitatively accurate magnetostriction curves for both homogenous Terfenol-D rod and magnetically ordered Terfenol-D particulate actuated epoxy matrix composites over experimental applied field ranges. Model calculations clearly indicate that the particle actuated composites developed less longitudinal strain than would be expected from the behavior of the homogeneous material. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372294
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  • 5
    Electronic Resource
    Electronic Resource
    A directional magnetization potential based model of magnetoelastic hysteresis (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2202-2210 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The theory presented in this article successfully reproduces and explains the experimental magnetostriction and magnetization hysteresis behavior of Tb0.3Dy0.7Fe1.9. It is well known that a very large number of individual domain wall translation events combine to produce each measurable domain transformation in a macroscopic sized sample. Each individual domain wall may be expected to suffer some level of domain wall translation inhibition due to the presence of defects in the material, however, the severity of the inhibition will spatially vary. We therefore assume that the presence of defects in the material increases the directional magnetization potential of subsequent domain states within a process, and distributes nontrivial probabilities of occupation of 〈111〉 type domain states in a parameter selected, inverse exponential form familiar from the study of statistical thermodynamics. The increased magnetization potential of subsequent high magnetostriction and high magnetization states retards their occupation until higher intensity applied magnetic fields are produced, thus shifting the increasing applied magnetic field curve in a positive field direction and shifting the decreasing applied magnetic field curve in a negative field direction in a form consistent with experiment. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1431433
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetization and magnetostriction processes in Tb(0.27−0.30)Dy(0.73−0.70)Fe(1.9−2.0) (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2321-2326 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The present analysis provides Tb(0.27−0.30)Dy(0.73−0.70)Fe(1.9−2.0) magnetization and magnetostriction states during applied magnetic field and stress processes by minimizing the total magnetic free energy in the presence of a parameter selected inverse exponential magnetic free energy distribution. A comparison between experimental and model results shows that the model provides a qualitatively accurate description of the magnetostriction and magnetization in Tb(0.27−0.30)Dy(0.73−0.70)Fe(1.9−2.0) during applied magnetic field processes for a range of constant uniaxial applied stresses. Therefore, the model appears to be a useful tool for the analysis of Tb(0.27−0.30)Dy(0.73−0.70)Fe(1.9−2.0) applications with constant stress or strain dependent stress states. Furthermore, the good qualitative agreement between model and experiment supports the contention that the magnetostriction and magnetization response of Tb(0.27−0.30)Dy(0.73−0.70)Fe(1.9−2.0) is influenced by a defect induced defocusing of local magnetization direction about the average magnetization direction. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364235
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  • 7
    Electronic Resource
    Electronic Resource
    Stress-dependent dynamic compliance spectra approach to the nonlinear viscoelastic response of polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2301-2309 
    Details
    ISSN: 0887-6266
    Keywords: discrete dynamic compliance spectra ; nonlinear viscoelasticity ; creep ; stress relaxation ; constant strain rate tests ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The present work reports a discrete, stress-dependent dynamic compliance spectra method which may be used to predict the mechanical response of nonlinear viscoelastic polymers during strain-defined processes. The method is based on the observation that the real and complex parts of the discrete dynamic compliance frequency components obtained from creep measurements are smooth, easily fit functions of stress. Comparisons between experimental measurements and model calculations show that the model exhibits excellent quantitative agreement with the basis creep measurements at all experimental stress levels. The model exhibits good quantitative agreement with stress relaxation measurements at moderate levels of applied strain. However, the model underestimates the experimental stress relaxation at an applied strain of 3.26%. The stress relaxation error appears to be a real material effect resulting from the different strain character of creep and stress relaxation tests. The model provides a good quantitative agreement with experimental constant strain rate measurements up to approximately 4% strain, after which the model underestimates the experimental flow stress. This effect is explained by the time dependence of the stress-activated configurational changes necessary for large strains in glassy polymers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2301-2309, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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