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'Resonance Frequency' in keywords
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1992 (1)
1981 (1)
1Author    U. Zimmermann, J. Vienken, G. PilwatRequires cookie*
 Title    Rotation of Cells in an Alternating Electric Field: the Occurrence of a Resonance Frequency  
 Abstract    Cells suspended in a low-conducting medium were exposed to an alternating electric field whose frequency was altered between 1 kHz and 2 MHz. A resonance frequency was observed at which all suspended cells rotated about an axis normal to the field lines (when the electric field strength was larger than a threshold value of about 400 V/cm). This resonance frequency varied from species to species o f cells (mesophyll protoplasts of Avena sativa = 2 0 -4 0 kHz, human erythrocytes and ghost cells = 8 0 -1 0 0 kHz, yeast cells = 140-180 kHz, Friend cells = 3 0 -4 0 kHz, at room temperature). The resonance frequency o f cell rotation was observed only under specific experimental conditions which excluded interference by reversible electrical breakdown of cell membranes and by gravitational forces. Glutardialdehyde fixed and heated cells exhibited no rotation in the frequency and field range investigated. The phenomenon o f rotation is discussed in terms 
  Reference    Z. Naturforsch. 36c, 173—177 (1981); received October 22 1980 
  Published    1981 
  Keywords    Electric Field, Cell Rotation, Dipole, Cell Membrane, Resonance Frequency 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0173.pdf 
 Identifier    ZNC-1981-36c-0173 
 Volume    36 
2Author    S. Gärtner, H. Riesemeier, Y. Kitaoka, V. Müller, K. Lüders, E. Kaldis, S. RusieckiRequires cookie*
 Title    Cu-NQR Frequencies and Linewidths in High-T c Superconductors  
 Abstract    The Cu-NQR lines of various high-T c superconductors at the Cu(2) site appear between 15 and 40 MHz. There exists an experimental correlation showing that the NQR frequency increases with decreasing T c . By comparison, it can be concluded from these results that a formal valence state of the Cu ion around 2 + is favourable for superconductivity. All lines exhibit a strong broadening compared to Cu0 2 crystals, which is attributed to lattice modulations within the Cu0 2 layers. This effect also influences the temperature dependence of the linewidth in YBa 2 Cu 3 0 7 _ a . 
  Reference    Z. Naturforsch. 47a, 27—29 (1992); received August 3 1991 
  Published    1992 
  Keywords    NQR, Superconductivity, High-T c compounds, Resonance frequency, Linewidth 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0027.pdf 
 Identifier    ZNA-1992-47a-0027 
 Volume    47