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'Relaxation processes' in keywords
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1989 (1)
1982 (1)
1Author    W. M. Arnold, U. Zim, Erm AnnRequires cookie*
 Title    Rotating-Field-Induced Rotation and Measurement of the Membrane Capacitance of Single Mesophyll Cells of A vena sativa  
 Abstract    Rotation of single cells (mesophyll protoplasts o f Avena sativa) induced by a planar, homogeneous rotating field has been observed at a frequency o f 2 0 -4 0 kHz (conductivity o f the external mannitol solution 6 x 10-5 ß -1 cm-1). This variation in optimum frequency is largely due to an inverse dependence on cell radius. Rotation direction is opposite to that o f the field, and can be reversed at will by reversing the field. The maximum speed o f cell spinning was a few cycles per second (and thus always much slower than that o f the field) and was proportional to the square o f the amplitude of the field. The rotation o f a single cell in a rotating field is expected on the basis o f the dipole-dipole theory developed by Holzapfel et al., (J. Membrane Biol. 67, 1 -1 4 (1982)), for multi-cell rotation. Measurements of the dependence of optimum applied field frequency on medium conductivity indicate that the dipole is generated by interfacial (Maxwell-Wagner) polarization. The required frequency is a linear function o f the conductivity of the external solution. This relationship is used to derive a value for the specific membrane capacitance. Further applications o f this technique for cell and membrane research are discussed. 
  Reference    Z. Naturforsch. 37c, 908 (1982); received July 15 1982 
  Published    1982 
  Keywords    Rotating Electric Field, Protoplast Rotation, Relaxation Processes, Characteristic Frequency, Membrane Capacitance 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0908.pdf 
 Identifier    ZNC-1982-37c-0908 
 Volume    37 
2Author    J. Peinke, J. Parisi, U. Rau, W. Clauß, M. WeiseRequires cookie*
 Abstract    h a r a c te r is tic R e la x a tio n T im e s o f L o w -te m p e ra tu re S e m ic o n d u c to r B re a k d o w n K in e tic s The nonlinear transport behavior during low-temperature avalanche breakdown of extrinsic germanium is associated with the self-generated formation of spatio-temporal current structures. Very close to the critical phase transition between different conducting states, the underlying physical relaxation processes develop on relatively slow macroscopic time scales in the ms range. We have evaluated the slowing down of the characteristic time constants from independent measurements of the system response behavior to external pulsed excitations. 
  Reference    Z. Naturforsch. 44a, 629 (1989); received April 28 1989 
  Published    1989 
  Keywords    Semiconductor breakdown, Nonequilibrium phase transition, Structure formation, Nonlinear carrier transport, Relaxation processes 
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 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-0629.pdf 
 Identifier    ZNA-1989-44a-0629 
 Volume    44