Function Of Electric Field Intensity Research Articles

Optical absorption in core–shell quantum antidot with donor impurity under applied co-directed electric and magnetic fields

In this article, we have investigated an electron energy spectrum, optical absorption coefficients (OACs) and polarizability under the effect of the co-directed electric and magnetic fields in the multilayer spherical quantum antidot (MSQAD) Al0.3 Ga0.7 As/GaAs/Al0.3Ga0.7 As with off-center impurity. The calculations were done for different dot sizes within the effective mass approximation using the matrix method. The dependence of the total, linear, and nonlinear OACs on the incident photon energy is calculated considering the intraband electron quantum transitions. The donor polarizability and impurity binding energy as function of electric field intensity are obtained at different values of the magnetic field induction.

Correlation between impulse magnitude and inhibition of cell proliferation in alternating electric fields therapy

This study was designed to investigate the correlation between the impulse by dielectrophoretic force applied inside a dividing cell during alternating electric fields therapy and the inhibition of cell proliferation. Distributions of the electric field and dielectrophoretic force inside a dividing cell were calculated using the finite element method of COMSOL Multiphysics. Based on the results, the average magnitude of the impulse by the dielectrophoretic force applied to the cleavage furrow inside a dividing cell placed in various directions was calculated as a function of electric field intensity at an extracellular reference point. The simulation results showed that the average magnitude of the impulse to the cleavage furrow inside a dividing cell ranged from 1.51 × 10−9 to 1.49 × 10−7 N s when tumor treating fields with an intensity ranging from 0.1 to 1 V/cm is applied at an extracellular reference point for 6 h. To verify the relationships between the impulse by the dielectrophoretic force and the inhibition of cell proliferation, the survival fractions of the four cancer cell lines were determined as a function of intensity and time duration of the electric field. The correlation between the magnitude and application time of the electric field and the survival fractions of the four cell lines showed similar trends in vitro. These results suggest that both the dielectrophoretic force and the time required for the force to act are proportionally related to the inhibitory effect on dividing cells, enabling this impulse to be used as a reference to quantify the inhibition of cell proliferation.

Electrical field enhanced interfacial Dzyaloshinskii-Moriya interaction in MgO/Fe/Pt system

We report electric field control of the interfacial Dzyaloshinskii-Moriya interaction (DMI) in MgO/Fe/Pt multilayers. The interfacial DMI is obtained and quantified by Brillouin light scattering measurements based on the frequency nonreciprocity of spin waves in a ferromagnet. The magnitude of the induced DMI is found to linearly increase as a function of electric field intensity. The efficiency of electric field control of the interfacial DMI characterized as a ratio of the DMI energy change to the electric field, which is found to be equal to 67 fJ/(Vm) with a positive electric field. We further demonstrate that the origin of the enhanced DMI results from the MgO/Fe interface. The Rashba spin-orbit coupling and electric field induced anisotropy at the MgO/Fe interface might be responsible for the enhanced interfacial DMI. Our findings open up a way for exploring the spintronic devices with a tunable DMI.

Optical properties of GaAs/Al_{x}Ga_{1-x}As/GaAs quantum dot with off-central impurity driven by electric field

The effect of a constant electric field and donor impurity on the energies and oscillator strengths of electron intraband quantum transitions in double-well spherical quantum dot GaAs/Al$_{x}$Ga$_{1-x}$As/GaAs is researched. The problem is solved in the framework of the effective mass approximation and rectangular potential wells and barriers model using the method of wave function expansion over a complete set of electron wave functions in nanostructure without electric field. It is shown that under the effect of electric field, the electron in the ground state tunnels from the inner potential well into the outer one. It also influences on the oscillator strengths of intraband quantum transition. The binding energy of an electron with ion impurity is obtained as a function of electric field intensity at a different location of impurity.

CURRENT DISTRIBUTION DEPENDENCE ON ELECTRIC FIELD IN HELICALLY COILED CARBON NANOTUBES

Experimentally is confirmed that helically coiled carbon nanotube (HCCNT) could be used as a small solenoid for generating spatially localized magnetic field. Current distribution during diffusive electronic transport likewise the inductivity of this quantum conductor depends on electric field. Despite slightly lower electron mobility in HCCNTs than that of the straight single wall carbon nanotubes, the coiled nanotubes are attractive for application as nonlinear nano-solenoids. Nonequilibrium electron distribution functions obtained by solving Boltzmann transport equation are used to predict average helical radius of current flow as a function of electric field intensity. Change of spatial distribution of electronic flow with applied electric field is considered and nonlinear inductivity of HCCNT is predicted.

CURRENT DISTRIBUTION DEPENDENCE ON ELECTRIC FIELD IN HELICALLY COILED CARBON NANOTUBES

Experimentally is confirmed that helically coiled carbon nanotube (HCCNT) could be used as a small solenoid for generating spatially localized magnetic field. Current distribution during diffusive electronic transport likewise the inductivity of this quantum conductor depends on electric field. Despite slightly lower electron mobility in HCCNTs than that of the straight single wall carbon nanotubes, the coiled nanotubes are attractive for application as nonlinear nano-solenoids. Nonequilibrium electron distribution functions obtained by solving Boltzmann transport equation are used to predict average helical radius of current flow as a function of electric field intensity. Change of spatial distribution of electronic flow with applied electric field is considered and nonlinear inductivity of HCCNT is predicted.

The effect of electric field, annealing temperature and filler loading on the percolation threshold of polystyrene containing carbon nanotubes and graphene nanosheets

The electrical resistance of polystyrene sheets containing carbon nanotubes (CNTs) and graphene nanosheets (GNSs) was examined as a function of electric field intensity and annealing temperature. The time needed for the percolation threshold to be reached, decreases with increasing field intensity, annealing temperature and filler loading. However, conductive networks were always formed more easily in GNS composites than did CNT composites. The activation energies for conductive network formation were about 80 and 100 kJ/mol for GNS and CNT, respectively. Structural observations show that the conductive particles could overcome the polymer barrier films and construct a multitude of conducting pathways under the influence of the electric field. A model is proposed to account for the distribution of the different nanofillers in the polymer matrix before and after application of the electric field. The results indicate that the geometry of the nanoparticles greatly affects the ease of formation of conductive networks in polystyrene.

A determination of the effective temperatures for the dissociation of the proton bound dimer of dimethyl methylphosphonate in a planar differential mobility spectrometer

The dissociation of the proton bound dimer of dimethyl methylphosphonate to the protonated and neutral molecule has been studied in a planar differential mobility spectrometer. The internal energy of the ions is the sum of the thermal component and the electric field component and results in an effective temperature, Teff, that is significantly greater than that of the ambient atmosphere temperature, T. The measured rate constant for dissociation, which rises exponentially with field strength, together with activation energy and pre-exponential factor previously determined under thermal conditions, allow the calculation of Teff as a function of electric field strength. Teff is a linear function of electric field intensity at constant T over the range of T from 60 °C to 140 °C. The efficiency of the available collision energy in causing dissociation decreases with increasing T, from 52% at 60 °C to 40% at 140 °C.

Parallel conduction in p-type gallium nitride homo-structures

Usually the multi-layer technique is applied for the growth of p-type gallium nitride (GaN) films, and the active p-type layer is deposited on an n-type GaN buffer layer. In the present paper, the electrical transport phenomena (conductivity and Hall effect) have been studied in p-GaN/GaN homo-structures grown on a sapphire substrate. Two types of GaN buffer layers were used: a silicon-doped one and another strongly compensated by magnesium. We demonstrate that in the analysis of the electrical conduction phenomena the parallel conduction in the n-type buffer layer cannot be neglected, and it manifests itself in the studies of a conduction process as a function of temperature and as a function of electric field intensity.

Modelling the inactivation of Escherichia coli ATCC 25922 using pulsed electric field

Abstract Microbial tests were conducted to determine the effect of pulsed electric field treatment on microbial inactivation of gram negative Escherichia coli ATCC 25922 suspended in simulated milk ultra filtrate (SMUF). Kinetic analysis of microbial inactivation due to combined pulsed electric field (PEF) and thermal treatments of E. coli was investigated. A generalized correlation for the inactivation rate constant as a function of both electric field intensity and treatment temperature was derived. Comparison between experimental and theoretical variation of E. coli concentration with time after PEF treatment in a complete recirculation mode was conducted using the inactivation kinetics developed from the single pass measurements. Industrial relevance PEF technology has a tremendous potential to replace thermal pasteurisation for products which are sensitive to temperature. In this work a pulsed electric field process was mathematically modelled and a generalized correlation for the inactivation rate constant as a function of electric field intensity and treatment temperature was derived. The correlation is needed for the design of industrial PEF systems.

Dielectric properties of betaine arsenate crystal near the phase transition

Dielectric measurements for single crystal of betaine arsenate ( CH 3 ) 3 NCH 2 COO · H 3 AsO 4 connected with the ferroelectric phase transition at 119 K were performed. The temperature dependence of electric permittivity was measured at dc electric fields up to 700 kV/m. The results show significant suppression of the dielectric constant by the application of dc field. Deviation from the classical behavior was observed. The electric permittivity was also measured in the paraelectric phase at constant temperature as a function of electric field intensity up to 700 kV/m. The electric permittivity might be well described by the classical relation with additional term including contribution to permittivity coming from clusters. The fit parameters indicate that the polar-clusters carries polarization P 0 = 0.7 – 4 . 910 - 3 cm 2 with the clusters size of L = 12 –20 nm.

Confinement and Manipulation of Actin Filaments by Electric Fields

When an AC electric field was applied across a small gap between two metal electrodes elevated above a surface, rhodamine-phalloidin-labeled actin filaments were attracted to the gap and became suspended between the two electrodes. The variance 〈 s 2 (x)〉 of each filament’s horizontal, lateral displacement was measured as a function of electric field intensity and position along the filament. 〈 s 2 (x)〉 markedly decreased as the electric field intensity increased. Hypothesizing that the electric field induces tension in the filament, we estimated the tension using a linear, Brownian dynamic model. Our experimental method provides a novel means for trapping and manipulating biological filaments and for probing the surface conductance and mechanical properties of single polymers.

Characterization of phase transition in new ferroelectric 2‐aminopyridine phosphate crystal

AbstractThe dielectric properties of 2‐APP, a new ferroelectric crystal, were investigated around the ferroelectric phase transition at 103.5 K. The temperature dependence of electric permittivity was measured at dc electric fields up to 1000 kV/m. The electric permittivity was also measured in the paraelectric phase at constant temperature as a function of electric field intensity up to 150 kV/m. The results are discussed in the framework of the classical dielectric state equation and expansion coefficients A, B and C were estimated. It is found that the phase transition is of second order. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Calculated profiles of H I lines of interest for solar plasma electric field measurements

We present calculated Stark-polarized line profiles for a number of H i lines observed in the visible and infrared emission spectrum of solar prominences and other limb activity. For use in measurements of possible electric fields in these structures, we also calculate curves giving the difference in line width between the 1/2 (I ± Q) profiles as a function of electric-field intensity. Our calculations take into account magnetic fields in these structures, and incorporate typical observed values of Doppler broadening. These calculations explicitly consider the H i fine structure neglected in previous work, and thus are more accurate in the range of low to intermediate electric-field intensity likely to be encountered in solar plasmas (E < 103 V cm−1). Our results enable us to compare behavior when E and B are parallel, or perpendicular. We draw particular attention to the high electric-field sensitivity of the transitions between high levels such as 12–8 and 15–9 in H i, observed in prominences at wavelengths around 11μ. Their sensitivity is roughly an order of magnitude larger than that of the high Paschen-series lines used in solar plasma electric field studies so far.

Hot-electron intervalley transfer in silicon

Using symmetry considerations developed in a previous paper it is shown that, assuming ellipsoidal parabolic band structure, the populations of the valleys as a function of electric field intensity $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}$ can be deduced from drift-velocity measurements when $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}$ lies in the (110) plane. This is, as we know, the first direct determination of the transfer rate $r(E)$ of electrons between valleys, which does not involve any hypothesis concerning the scattering mechanisms and the coupling constants. $r(E)$ is plotted versus $E$ for different lattice temperatures and impurity concentrations when $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}\ensuremath{\parallel}[100]$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}\ensuremath{\parallel}[110]$ crystallographic directions. It is shown that the depopulation of the "hot" valleys reaches 50% at 77\ifmmode^\circ\else\textdegree\fi{}K for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}\ensuremath{\parallel}[100]$, and is a decreasing function of the lattice temperature and of the impurity concentration. Ninety percent of the drift-velocity anisotropy is due to intervalley transfer. At very high electric fields the carriers are again equipartitioned among the valleys. At low temperature the "hot" valleys become almost empty in a range of electric fields and this produces negative differential mobility.

Thick film capacitor with a rutilium dielectric: é and [formula omitted]. Onde Elec.52, No. 3, March (1972), p. 140. (In French.)

In this paper a method for manufacturing capacitors in which the insulation is made from a mixture of rutilium (TiO 2) and glass powders, is discussed. The dependence of electric permittivity and losses on the content of TiO 2 in the dielectric, are tested. Much attention has been paid to the capacitors containing 90 per cent of TiO 2 (in respect of weight) in their insulation which have been protected with a silicone varnish against ambient moisture effects. The conductivity of their insulation as a function of electric field intensity and ambient temperature has also been measured. The capacity changes and tan δ have been defined in a wide frequency band and with respect to temperature. The capacitor response in long periods of operation under various ambient conditions has been checked.

The electroconductance of polymeric semiconductors as a function of electric field intensity

MANY of the polymeric semiconductors of low [l, 2] and high molecular weight (mol.wt.) [3-10] show non-ohmic volt-ampere characteristics in the intensity range from l0 3 to 10 6 V/cm, i.e. the electric current i increases more quickly than indicated by Ohm's law for an electric field intensity increase. The non-ohmic behaviour of such materials can generally have different reasons, especially: a) the polarizo, tion produced by an irregular distribution of the free charges in depth, or of the polar group orientation in the sample; b) the electron emission from the cathode, or electron generation inside the sample due to the effect of a strong electric field; c) the injection of ions into the volume of the sample from the bundary between the metal and semiconductor as a result of the presence of electrolytic impurities; d) an increase in the movement of charge carriers with increasing field intensity, and finally, e) additional dissociation of weakly linked ionic pairs, due to the strong electric field. The true electroconducta~lce, ai, as a flmction of E will thus depend on the influence of the electric field on the movement of the charge carriers, /I, and of their concentration, n, i.e.