Frohlich's Theory Research Articles

Temperature dependence of DC electrical tree initiation in silicone rubber considering defect type and polarity

In this article, the electrical tree initiation behavior in silicone rubber (SIR) under DC voltage was studied. Tests were conducted to reveal the effects of temperature (20–120 °C), defect type and voltage polarity on electrical tree initiation. In samples with an undamaged needle-tip (N samples), we find that the average tree initiation voltage (Fa«) decreases exponentially with increasing temperature by 42%. Single-branch trees and multiple-branch trees are observed. The probability of generating multiple-branch trees decreases with increasing temperature. In samples where an air gap or crack is in the needle (AN samples), Vati is 55.7% of that in N samples at 20 °C. In AN samples, Vati and tree shape do not change monotonically and Vati varies in a small range as temperature rises. Vati for N samples under negative voltage is much larger than that under positive voltage. This polarity effect is reversed in AN samples. Gas discharge theory and Frohlich's theory of dielectric breakdown explain electrical tree initiation behavior at different temperatures. Based on differential scanning calorimetry (DSC) results, we believe that partial segment relaxation of SIR at high temperature leads to Vati decreasing. Electrical trees previously generated inside the cable or an air gap created due to mechanical damage cause Vati to of a subsequently generated tree to drop to nearly half of its typical level. This information is useful for the design of HVDC cable insulation.

Dielectric relaxation of dihydric alcohol–1,4-dioxane mixtures using time domain technique

Complex dielectric permittivity measurements of 1,2-propanediol–1,4-dioxane mixtures has been carried out at different concentration and in the frequency range of 10 MHz to 20 GHz using time domain reflectometry (TDR). The least squares fit method has been used to obtain the static dielectric constant, relaxation time, and Bruggeman factor for binary mixtures. The Kirkwood–Frohlich theory is applied to compute the dielectric constant for the mixtures. It adequately reproduces the experimental values of static dielectric constants for the 1,2-propanediol–dioxane mixtures. The excess parameters confirm that the heteromolecular hydrogen bonding interactions between 1,2-propanediol and dioxane molecules vary significantly in the mixture. The Bruggeman model for the nonlinear case has been fitted to the experimental dielectric data for mixtures. Keywords: dielectric relaxation, time domain reflectometry, alcohols

A Kink-Soliton Model of Charge Transport through Microtubular Cytoskeleton

Contemporary trends in science and technology are characterized by integration of biological and technical systems, like in nanotechnology, nanobiology, and quantum medicine. In our case, we were motivated by a necessity to understand charge transport through microtubular cytoskeleton as a constitutive part of acupuncture system. The high frequency component of acupuncture currents, widely exploited in microwave resonance stimulation of acupuncture system in the past decade, implies that explanation of the cytoplasmatic conductivity should be sought in the framework of Frohlich theory. Accordingly, in this paper we critically analyze the problem of the microwave coherent longitudinal electrical oscillations as a theoretical basis for understanding soliton phenomena in microtubules, showing that charged kink-soliton nonlinear microtubular excitations might be a good candidate for charge transport in microtubules.

Hydrogen bond thermodynamic properties of water from dielectric constant data

We apply statistical mechanical principles to derive simple expressions relating the hydrogen bond thermodynamic properties to the static dielectric constant of water. The approach followed by us was to develop an expression for the Kirkwood’s structure factor (g) of water, taking into account the dipolar correlations between a central molecule and H-bonded neighbors present in infinite number of shells surrounding the central molecule. The number of H-bonded neighbors in a specific shell was related to the probability P for the various donor/acceptor sites of any given water molecule to be associated. Neglecting cooperativity effects, we evaluated P by focusing only on the correct counting of H-bonds formed between various association sites rather than on the oligomer distribution. The theory yielded an extremely simple expression for the structure factor (g) of the fluid at any given temperature in terms of the enthalpy (H) and entropy (S) changes associated with bond formation. The proposed theory was then combined with the Kirkwood–Frohlich theory for evaluating the dielectric constant (ε0). We have demonstrated that the theory correctly predicts the dielectric constant of ice-I without the use of any adjustable parameters. We have then deduced estimates for H-bond thermodynamic properties (H=−5.58 kcal/mole of H-bonds; S=−8.89 cal/deg⋅mole of H-bonds) by fitting the theoretical results for ε0 of liquid water to available experimental data over temperatures ranging from 0 °C to the critical point of water. The error in the theoretical values was found to be within 1% of the corresponding experimental values over the entire range of temperatures studied. To further test the theory, we have demonstrated that the temperature variation of the average number of H-bonds per water molecule, calculated using the proposed theory with the above mentioned values for H and S, compares quite well with those estimated from various available spectroscopic and molecular simulation studies.

Association of pure polar liquids: dielectric properties of docosanoic acid

The dielectric properties of liquid docosanoic acid as a function of temperature have been studied in order to establish a possible link between these properties and the association of monocarboxylic fatty acids. Measurements of the static dielectric permittivity are reported at different temperatures from ca. 10 K above the mp to 388 K. The molecular correlation factor has been evaluated according to the Kirkwood–Frohlich theory and has also been corrected on the basis of the Abbott–Bolton model, to take into account the non-spherical molecular shape. The static permittivity is almost constant over the considered temperature range, but the correlation factor tends towards unity because of thermal agitation as the temperature increases.

Application of the Fröhlich theory to the modelling of rouleau formation in human erythrocytes

The details of Frohlich's theory and some recent experiments on the rouleau formation of human erythrocytes which exhibit a strong interaction that appears to satisfy the prerequisites of the Frohlich theory, are summarized. To verify whether the Frohlich theory of long-range coherence in biological systems is applicable to the phenomenon of rouleau formation in human erythrocytes, the interactions between erythrocytes are modelled as those between two large, coupled oscillating dipoles. Relevant expressions for the resonant long-range and the van der Waals interaction are then derived. Using the available numerical data, the eigenfrequencies and the interaction energies corresponding to the experimental conditions are then derived. In the range of postulated frequencies (1011–1012 Hz) the effective interaction coefficient Ξ due to the resonant long-range forces is, indeed, found to agree with its experimental value of 3.0. However, the same value of Ξ can also be achieved through the ordinary van der Waals interactions between dipoles oscillating at lower frequencies. It is concluded that the resonant long-range interaction between erythrocytes may be responsible for the onset of rouleau formation. However, other mechanisms cannot be ruled out at this stage, especially since the Frohlich mechanism requires a number of unconfirmed preconditions.

Quantum mechanical coherence in human red blood cells

Fritz London predicted that the behavior of the quantum fluids “...might prove useful for an understanding of the macromolecular systems of biology which behave... much more simply than would be expected in view of the apparent great complexity of their structure.” The Frohlich theory is of an energy-driven laserlike process in living cells which should drive cellular phonons into coherence. Frohlich's theory predicts specific ultra-long-range forces which can explain the presently mysterious, ordered tensor interactions within and without the living cell. Several different types of experiments demonstrate a specific ultralong-range interaction between mammalian red blood cells which accords with the postulates of the Frohlich theory. One phenomenon seems to be compatible with processes analogous to self-focusing and trapping in nonlinear optics. As work progresses more and more biological mechanisms appear to be similar to those known in condensed matter physics.

Dipole correlation functions and Kirkwood g(1) factor in liquid chlorobenzene

The Kirkwood g(1) factor for room temperature liquid chlorobenzene has been measured from (a) the integrated intensity of the far IR rotation-translation band, and (b) the long time slopes of the single-particle and total-particle dipole correlation functions, using the Keyes–Kivelson rotational diffusion model. The values are 1.13±0.11 and 1.18±0.10, respectively, and do not agree with the Kirkwood–Frohlich theory, which predicts 0.83. The vibrational and far IR band shapes are presented, along with their second moments and the dipole correlation functions. The vibrational band second moment is within experimental error of the theoretical value; the far IR band second moment is in excess by 153%.

Monte-Carlo Studies of the Electron Mobility in SiO2

The motion of quasi-free electrons in SiO2 is simulated by means of the Monte-Carlo-method and the Frohlich theory of the electron—LO-phonon scattering. From the field dependence of the drift velocity an electron mobility of μ ≈ 20 cm2/Vs is deduced. The energy distributions of hot electrons indicate an electronic breakdown at the field strength F0 ≈ 2 × 106 V/cm. For higher excited electrons with initial energies E0 ≈ (1 to 5) eV a “partial breakdown” even at lower field strength F < F0 is observed.

Further evidence for a Fröhlich interaction of erythrocytes

Abstract The aggregation of red blood cells, of a single species and of mixtures of species, deviates from brownian aggregation theory. The deviations are compatible with Frohlich's theory of a quantum mechanical interaction between living cell membranes.

Bose condensation in biosystems

Abstract A microscopic approach to Frohlich's theory of Bose condensation in biological systems is discussed. The conclusions from this microscopic analysis offer further support for Frohlich's hypothesis.

The Ferroelectric Phase Transition in (Glycine)3·H2SO4 and Critical X-Ray Scattering

On the assumption that the ferroelectric phase transition in (Glycine) 3 ·H 2 SO 4 is of the order-disorder type, expressions for Bragg reflections and critical scattering of X-rays are given in terms of a long-range order parameter and pair correlation functions. Temperature dependence of the critical scattering is discussed on the basis of the Bragg-Williams approximation and of a modified Frohlich theory. Experimental observations agree with theoretical predictions, and prove that the phase transition is of the order-disorder type. The observed critical scattering exhibits a pronounced peak at the Curie point, suggesting that the local field theory is not a good approximation. The shape of the peak appears to be quite different from that in the ferromagnetic case. It has been found that the sulfur atoms do not shift appreciably when the glycine groups rotate. A method for evaluating the pair correlation function is proposed.

Dipole Moment Fluctuations of a Dielectric Body

Frohlich's theory of dielectrics has shown that a dielectric body will exhibit spontaneous fluctuations in dipole moment as a result of thermal agitation. It is pointed out that these fluctuations may arise from a variety of sources and that each source is intimately connected with a particular mechanism of polarization. The particular case of a dielectric which has two mechanisms of polarization (orientational and displacement) is considered. Frohlich's relations for the total mean square fluctuation in dipole moment of a dielectric sphere are modified so as to yield an expression for the fluctuations arising from only one polarization mechanism (the orientational). It is shown that Frohlich's free energy method of computing these fluctuations is independent of the dynamic properties of the dielectric. The recent work of Harris and Alder is shown to be in error.

Variation of the Electric Strength of KCl and NaCl Crystals with Temperature

The paper describes measurements of the electric strength of crystals of KCl and NaCl which were made using both d c. and standard 1/50 μsec unidirectional impulse voltages at temperatures between - 74° c and + 140° c. In this range of temperature, which included for both KCl and NaCl a transition from a region in which the electric strength increased with rise in temperature to one in which it decreased, no significant difference was found between values of electric strength obtained using d.c. and corresponding values obtained with impulses. This result contrasts with that of Suita for KCl. It supports qualitatively Frohlich's theory of breakdown.

A Note on Fr hlich's Theory of Superconductivity

It is shown that the physical mechanisms underlying the two energy terms E1 and E2 in Frohlich's theory are very different. E1 is largely the energy change due to a modification of the lattice vibration frequencies caused by the adiabatic deformation of the electrons; E2 is on the other hand a dynamical term, representing the energy change due to virtual collisions between lattice oscillations and electrons. A proof is given that certain inadmissible consequences of the theory, pointed out recently by Wentzel, derive from the energy term E1; the superconductive behaviour discussed by Frohlich arises however entirely from the term E2. Although both terms follow from the same perturbation treatment, the analysis given makes it seem not unlikely that whatever mechanism actually inhibits E1 will leave the superconductive behaviour deduced from E2 not substantially affected.

On the Interaction of the Lattice Vibrations with the Conduction Electrons

G. Wentzel') and W. Kohn and Vachaspati2) made comments on Frohlich's theory of superconductivity.3) The latter confimled that the shell construction in the momentum space is hardly possible if the interaction of the conduction electrons with the lattice phonons is so strong that Frohlich's condition of superconductivity is satisfied. The former applied Tomonaga's tneory of sound quanta4) to derive a similar result pointing out that the frequency of the lattice vibration becomes imaginary so far as Frohlich's condition is adopted. The objective of this report is two-fold; first we confirm the results, of the abovementioned authors by an extension of Tomonaga's theory given in our paperS) and next we examine Wentzel's suggestion that the motion of atom might become stable if the Coulomb interaction forces are taken into calculation. The result obtained is compared with that of the hydrodynamical treatment, the validity of which is computed from our point of view. When a conduction electron with wave number k absorbs a lattice phonon with wave number w, its wave number becomes k+w. Such a process and the reciprocal process are represented by the following operator

The Electric Strength of Dielectric Films

An attempt is made to verify the rise in electric strength predicted by Frohlich's theory as the thickness of the dielectric specimen approaches the electronic mean free path. The results obtained on a number of materials both crystalline and amorphous are given and discussed in relation to this theory.

The electric strength of mica and its variation with temperature

The electric strength of mica in air, and the intrinsic electric strength and d.c. conductivity of mica, have been measured over extensive ranges of temperature. The effects of thickness and pre-conditioning on electric strength have also been investigated. The experimental conditions necessary for the determination of intrinsic electric strength are considered and two methods suitable for mica are described. The intrinsic electric-strength values thereby obtained are shown to compare satisfactorily with the predictions of Frohlich's theory of electric breakdown in polar crystals. The relevance of the results to industrial applications of mica is discussed.

An examination of Frohlich's theory of the treppe

It is commonly believed that during the treppe a muscle possesses a progressively augmented power of performing work. According to Frohlich, the augmentation is not real but only apparent. He believes that fatigue of the muscle elements begins with the beginning of the series of contractions, and that, from the first, it is manifested by a slowing of relaxation, a diminution in the extent of contraction, and a diminution in irritability. Successive elements of a stimulated muscle contract successively and those first in contraction begin their relaxation before later elements have reached the maximum of shortening. Since the total amount of shortening of the whole muscle represents the algebraic sum of the amounts of shortening of the several elements, with the slowing of relaxation, the total amount of shortening is increased. This more than counterbalances the diminution in the extent of contraction. The treppe is thus a physical expression of delayed vital processes and signifies a diminished, rather t...