The Debye-Falkenhagen effect: experimental fact or friction?

Anderson, J. E.

doi:10.1016/0022-3093(94)90642-4

Cited by 30 publications

(17 citation statements)

References 7 publications

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“…The distribution function ( ) is written with one functional dependence, only on . It should be immediately obvious that a single function ( ) with functional dependence only on is unable to deal with the enormous range of dielectric properties observed experimentally in equilibrium measurements of linear dielectrics, for nearly a century, (Debye and Falkenhagen 1928, Debye 1929, Onsager 1936, Oncley, Ferry et al 1940, Oncley 1942, Fuoss 1955, Fröhlich 1958, Van Beek 1967, Nee and Zwanzig 1970, Böttcher, van Belle et al 1978, Anderson 1994, Barthel, Buchner et al 1995, Barthel, Krienke et al 1998a, Buchner and Barthel 2001, Pitera, Falta et al 2001, Oncley 2003, Prodromakis and Papavassiliou 2009). These measurements are now called impedance or dielectric spectroscopy (Macdonald 1992, Kremer and Schönhals 2003, Barsoukov and Macdonald 2005.…”

Section: Realistic Macroscopic Description Of the Currentsmentioning

confidence: 99%

Dynamics of Current, Charge and Mass

Eisenberg

Oriols

Ferry

2017

Computational and Mathematical Biophysics

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Electricity plays a special role in our lives and life. Equations of electron dynamics are nearly exact and apply from nuclear particles to stars. These Maxwell equations include a special term the displacement current (of vacuum). Displacement current allows electrical signals to propagate through space. Displacement current guarantees that current is exactly conserved from inside atoms to between stars, as long as current is defined as Maxwell did, as the entire source of the curl of the magnetic field. We show how the Bohm formulation of quantum mechanics allows easy definition of current. We show how conservation of current can be derived without mention of the polarization or dielectric properties of matter. Matter does not behave the way physicists of the 1800's thought it does with a single dielectric constant, a real positive number independent of everything. Charge moves in enormously complicated ways that cannot be described in that way, when studied on time scales important today for electronic technology and molecular biology. Life occurs in ionic solutions in which charge moves in response to forces not mentioned or described in the Maxwell equations, like convection and diffusion. Classical derivations of conservation of current involve classical treatments of dielectrics and polarization in nearly every textbook. Because real dielectrics do not behave in a classical way, classical derivations of conservation of current are often distrusted or even ignored. We show that current is conserved exactly in any material no matter how complex the dielectric, polarization or conduction currents are. We believe models, simulations, and computations should conserve current on all scales, as accurately as possible, because physics conserves current that way. We believe models will be much more successful if they conserve current at every level of resolution, the way physics does.Comment: Version 4 slight reformattin

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Section: Realistic Macroscopic Description Of the Currentsmentioning

confidence: 99%

Dynamics of Current, Charge and Mass

Eisenberg

Oriols

Ferry

2017

Computational and Mathematical Biophysics

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“…(8), (9) and (10), together with the boundary conditions Eqs. (11), (12) and (13) completely determine the electrostatic potential Φ( x). From the solutions for Φ( x) one can calculate other quantities.…”

Section: Inserting Eqs (3) Into Eq (1) Yields the Laplace Equationmentioning

confidence: 99%

“…(11), the condition that the potential is continuous, Eq. (12) and the fact that the displacement field is continuous, Eq. (13), we get 6 equations for the 6 constants φ 0 γ and A γ (γ = 1, 2, 3).…”

Section: Potential For a Flat Membranementioning

confidence: 99%

Applying a potential across a biomembrane: Electrostatic contribution to the bending rigidity and membrane instability

Ambjörnsson¹,

Lomholt²,

Hansen

2007

Phys. Rev. E

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We investigate the effect on biomembrane mechanical properties due to the presence an external potential for a nonconductive incompressible membrane surrounded by different electrolytes. By solving the Debye-Hückel and Laplace equations for the electrostatic potential and using the relevant stress-tensor we find (1) in the small screening length limit, where the Debye screening length is smaller than the distance between the electrodes, the screening certifies that all electrostatic interactions are short range and the major effect of the applied potential is to decrease the membrane tension and increase the bending rigidity; explicit expressions for electrostatic contribution to the tension and bending rigidity are derived as a function of the applied potential, the Debye screening lengths, and the dielectric constants of the membrane and the solvents. For sufficiently large voltages the negative contribution to the tension is expected to cause a membrane stretching instability. (2) For the dielectric limit, i.e., no salt (and small wave vectors compared to the distance between the electrodes), when the dielectric constant on the two sides are different the applied potential induces an effective (unscreened) membrane charge density, whose long-range interaction is expected to lead to a membrane undulation instability.

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“…Physically, the simpli®cations which underpin the validity of Eq. (14c) across the UHF are three: (i) to within the limits of reasonable experimental precision, the experimental uncertainties are such that the Debye±Falkenhagen effect can be neglected and the (ionic) conductivity s treated as a frequency-independent constant [Anderson, 1994]; (ii) the peak of the water relaxation is still nearly 20 GHz away, so that e H approximates its DC value while e HH is still increasing linearly with frequency; and (iii) s eff aoe eff Z is small enough to justify linearizing tan1a2arctanZ 1 2 Z1 À 1 4 Z 2 OZ 4 , an approximation which will hold to within about 20% throughout the UHF.…”

Section: Example: Brain Tissuementioning

confidence: 99%

Energy deposition processes in biological tissue: Nonthermal biohazards seem unlikely in the ultra-high frequency range

Pickard

Moros

2001

Bioelectromagnetics

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The prospects of ultra high frequency (UHF, 300--3000 MHz) irradiation producing a nonthermal bioeffect are considered theoretically and found to be small. First, a general formula is derived within the framework of macroscopic electrodynamics for the specific absorption rate of microwaves in a biological tissue; this involves the complex Poynting vector, the mass density of the medium, the angular frequency of the electromagnetic field, and the three complex electromagnetic constitutive parameters of the medium. In the frequency ranges used for cellular telephony and personal communication systems, this model predicts that the chief physical loss mechanism will be ionic conduction, with increasingly important contributions from dielectric relaxation as the frequency rises. However, even in a magnetite unit cell within a magnetosome the deposition rate should not exceed 1/10 k(B)T per second. This supports previous arguments for the improbability of biological effects at UHF frequencies unless a mechanism can be found for accumulating energy over time and space and focussing it. Second, three possible nonthermal accumulation mechanisms are then considered and shown to be unlikely: (i) multiphoton absorption processes; (ii) direct electric field effects on ions; (iii) cooperative effects and/or coherent excitations. Finally, it is concluded that the rate of energy deposition from a typical field and within a typical tissue is so small as to make unlikely any significant nonthermal biological effect.

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The Debye-Falkenhagen effect: experimental fact or friction?

Cited by 30 publications

References 7 publications

Dynamics of Current, Charge and Mass

Dynamics of Current, Charge and Mass

Applying a potential across a biomembrane: Electrostatic contribution to the bending rigidity and membrane instability

Energy deposition processes in biological tissue: Nonthermal biohazards seem unlikely in the ultra-high frequency range

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