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The interaction of electric and magnetic fields with biological materials

Jafary-Asl, A

Authors

A Jafary-Asl



Contributors

DC Smith
Supervisor

Abstract

In the course of the work on the interactions of
electric and magnetic fields with biological materials both
living and dead, 'it was noticed that published dielectrophoretic
yield curves for biological cells showed unexplained
deviations in the region of 2kHz which is the proton magnetic
resonance frequency in a typical laboratory ambient magnetic
field. The exact value is 2.13 kHz for a field of 50 UT.
The results of preliminary dielectrophoretic and
dielectric measurements show features at frequencies which
correspond to the NMR condition for that value of steady
magnetic field in which the measurements were made. Very
sharp dielectric loss peaks were found corresponding to
1H, 31
p,
23Na, 35C1
amd
39K
resonances. The electron spin
resonance also showed up in the dielectric loss.
The onset plus NMR conditions of these resonances commences
at the value of the steady magnetic field strength such that
one quantum of magnetic flux (2.07 x 10-15 Wb) would link
the cross-sectional area of a single biological cell or pair
of cells. Approximately 1.0 gauss or 0.5 gauss (100iT or
50pT) respectively in the case of 5um diameter yeast cell.
Growing cultures of the yeast cells in fields which satisfy
the proton NMR conditions as a function of temperature results
in a slight reduction in the mean generation time (MGT).
Comparison of this with the dielectric constant and loss
increments at the corresponding temperatures showed that
when the MGT is least, the cells are dividing most rapidly
and the dielectric increments are greatest.
Steps in the voltage-current characteristic of a pearlchain
of yeast cells were found to occur for a few minutes
around the time of cytokinesis as they were observed under
phase contrast microscope. The cells prepared for synchronous
division were collected by dielectrophoresis into a one
micron gap between two point electrodes mounted on a
microscope slide. Steps were observed about 3 to 4
hours later at ambient temperature. The mean generation time
is 4 hours.
An emission of a radio frequency signal from yeast cells
in the region of 7 MHz and in the range of 50 MHz -
80 MHz were found to occur about a mean generation time
after starting the incubation of the cells for synchronous
growth.
All these effects were only observed on the live yeast
cells and never observed in experiments using killed yeast
cells under the conditions otherwise same in all aspects.

Citation

Jafary-Asl, A. The interaction of electric and magnetic fields with biological materials. (Thesis). University of Salford, UK

Thesis Type Thesis
Deposit Date Jun 26, 2009
Publicly Available Date Jun 26, 2009
Additional Information Additional Information : PhD supervisor: Dr. C. W. Smith
Award Date Oct 1, 1983

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