Large Electric Charge Research Articles

Electric polarization and mechanism of B-type carbonated apatite ceramics

B-type carbonated apatite (CAp) ceramics, nonstoichiometric hydroxyapatites (HAp) with carbonate ions (CO(3)(2-) substituting for phosphate ions, are the major inorganic components of vertebrate bones. Due to the carbonate substitution, CAp is more biodegradable than HAp and has been expected a next generation biomaterial. We have reported the electric polarization of HAp, and induced stored electric charges and electric fields in poling HAp could promote bone healing. Here, we applied electric polarization to CAp and showed the role of substituted CO(3)(2-) concentrations in CAp in its electric polarization and polarization mechanisms. We found that the electrical conductivities (σ) and stored charges (Q) of poling CAp dramatically increased with carbonate ion contents. We also found that CAp showed higher activation energy both for conduction and for depolarization than HAp, even though the values of σ and Q are much higher than those of HAp. These results suggested that the substitution of a small amount of CO(3)(2-) for PO(4)(3-) resulted in a change in the conduction and polarization mechanisms in CAp compared with HAp. Our study showed that the poling CAp has the potential to be a new functional biomaterial with biodegradation and large stored electric charges.

Electrical Polarization of β‐Tricalcium Phosphate Ceramics

The β‐tricalcium phosphate (β‐TCP)‐sintered pellets and powders were prepared and the ability of β‐TCP to store an electrical charge by electrical polarization was studied. The prepared β‐TCP was characterized by X‐ray diffractometry and Fourier transform infrared spectroscopy. Alternating‐current impedance conductivity and the energy of activation required for the ionic migration of β‐TCP were calculated. After electrical polarization of synthesized β‐TCP, the thermally stimulated depolarization current was measured, and the total stored charges in the samples were calculated. The energy of activation for the relaxation of electrical polarization in the synthesized β‐TCP pellets and powders approximated the energy of activation required for ionic migration in the β‐TCP pellets. It was confirmed that β‐TCP has a suitable composition and structure for ion conduction and a large electrical charge is stored in both the β‐TCP pellets and powders. Instead of proton transport polarization in hydroxyapatite, other charge carrier, such as Ca2+ or O2−, is assumed in β‐TCP, in which proton is not contained.

Ferromagnetic properties of charged vector boson condensate

Bose-Einstein condensation of W bosons in the early universe is studied. It is shown that, in the broken phase of the standard electroweak theory, the condensed W bosons form a ferromagnetic state with aligned spins. In this case the primeval plasma may be spontaneously magnetizedinside macroscopically large domains and form magnetic fields which may be the seeds for the observed today galactic and intergalactic fields.However, in a modified theory, e.g. in a theory with stronger quartic self interactions of gauge bosons e.g. due to a smaller value of the weak mixing angle, antiferromagnetic condensation is possible. In the latter case W bosons form scalar condensate with macroscopically large electric charge density i.e. with a large average value of the bilinear product of W-vector fields but with microscopically small averagevalue of the field itself.

Dust particle current in the presence of an external electric field

Dusty plasmas consist of electrons, ions and dust particles. The latter usually have large electric charges of the order of 103–104 elementary charges. Although the dust particles move much slower than the electrons this large charge may, in the presence of an electric field, lead to an electric current which is not quite negligible with respect to the current carried by the electrons. Therefore, the dust particle current is calculated on the basis of the asymptotic solution obtained in this work of a generalized Fokker–Planck equation following from the kinetic theory.

Yang-Mills fields of nonstationary spherical objects with big charges

We study the nonlinear electrodynamics suggested in our paper in [Russ. J. Math. Phys. 12 (3), 379–385 (2005)] by using the Yang-Mills equations. This theory is intended to describe strong fields generated by objects with large electric charges. For nonstationary sources with spherical symmetry, we find formulas for the electric field strengths. This solution generalizes our previous result related to the stationary case. The corresponding formulas for nonlinear electric fields are used to explain some puzzling properties of the Earth atmosphere.

Gravitating dyons with large electric charge

We consider non-Abelian dyons in Einstein–Yang–Mills–Higgs theory. The dyons are spherically symmetric with unit magnetic charge. For large values of the electric charge the dyons approach limiting solutions, related to the Penney solutions of Einstein–Maxwell-scalar theory.

Can charge drag explain the Pioneer anomaly?

Abstract According to precise measurements of Doppler shift for the signals from Pioneers 10 and 11, these two spacecraft have been experiencing a drag-like force of about 2 × 10 −7 Newtons since they passed into the outer solar system. Recently, Nieto et al. [M.M. Nieto, et al., Phys. Lett. B 613 (2005) 11] have estimated the drag on these craft that would be caused by impacting dust grains in the region beyond 20 AU. They conclude that the amount of dust required to explain the anomaly is excessive, about 3 × 10 −19 g / cc . However, if the two spacecraft carry a large electric charge, then charge drag against the dusty plasma in this region could be significant. In the present Letter, estimates of this force are made, and conditions are found under which the observed level of drag is obtained. A density of charged dust of around 5 × 10 −22 g / cc at a kinetic temperature of 105 K suffices, provided that the dust grains are very small (mass ∼ 100 amu ) and the spacecraft charge is near its reported maximum ( Z ∼ 10 12 ).

Electric charge balance mechanism of extended soluble proteins

Extended proteins such as calmodulin and troponin C have two globular terminal domains linked by a central region that is exposed to water and often acts as a function-regulating element. The mechanisms that stabilize the tertiary structure of extended proteins appear to differ greatly from those of globular proteins. Identifying such differences in physical properties of amino acid sequences between extended proteins and globular proteins can provide clues useful for identification of extended proteins from complete genomes including orphan sequences. In the present study, we examined the structure and amino acid sequence of extended proteins. We found that extended proteins have a large net electric charge, high charge density, and an even balance of charge between the terminal domains, indicating that electrostatic interaction is a dominant factor in stabilization of extended proteins. Additionally, the central domain exposed to water contained many amphiphilic residues. Extended proteins can be identified from these physical properties of the tertiary structure, which can be deduced from the amino acid sequence. Analysis of physical properties of amino acid sequences can provide clues to the mechanism of protein folding. Also, structural changes in extended proteins may be caused by formation of molecular complexes. Long-range effects of electrostatic interactions also appear to play important roles in structural changes of extended proteins.

Electrosurface properties of poly(ethylene terephtalate) track membranes

The electrosurface properties of track membranes made from poly(ethylene terephtalate) were determined by streaming potential (SP) and electron spin resonance (ESR) methods. The membrane pore diameters were in range from 20 to 200 nm. The pore electrical charge surface density values calculated with data obtained with methods mentioned differed dramatically. This difference was explained with the gel layer located at pore surface. The pore possesses a high large surface amassing a large electrical charge arising as a result of carboxylic groups dissociation. This charge cannot be detected with SP method due to high hydraulic resistance of the gel layer. In contrast to SP method, ESR detects all active centres parental of electrical charge at gel surface.

Bisphosphonate chelating agents: complexation of Fe(III) and Al(III) by 1-phenyl-1-hydroxymethylene bisphosphonate and its analogues

Bisphosphonate ligands were found to be very efficient chelating agents for both Al(III) and Fe(III) ions. Potentiometric and spectroscopic data allow evaluation of the coordination equilibria in the solutions containing 1-phenyl-1-hydroxymethylene bisphosphonate and its three analogues with Al(III) and Fe(III) ions. At pH below 4 the bis-complexes are formed, while above pH 4 the major species are equimolar, monomeric for Al(III) or dimeric for Fe(III) complexes. The large steric hindrance and high electric charge are the major factors influencing the complex stoichiometry. The formation of the dimeric Fe(III) with μ-oxo or μ-hydroxo bridges were supported by measurements of the magnetic moments using Evans’ method. The stabilities of the complexes formed are higher than those found for deferiprone, L1, used in clinics as a chelating agent.

Layered, Erasable Polymer Multilayers Formed by Hydrogen-Bonded Sequential Self-Assembly

Robust multilayers can be formed on solid surfaces, and subsequently destroyed by changing the environmental conditions, by the layer-by-layer sequential assembly of monomolecular films of a polyacid and polybase from aqueous solution. Interlayer hydrogen bonding produces stable multilayers up to the point where altered pH or other environmental stimulus introduces an unacceptably large electrical charge within them. This is demonstrated for the polyacids poly(acrylic acid), PAA, and poly(methacrylic acid), PMAA, and for the polybases poly(vinylpyrrolidone), PVPON, and poly(ethylene oxide), PEO, in D2O. The adsorption was quantified by Fourier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR). The ratio between suppressed ionization of the carboxylic groups within the film and their ionization in solution, as directly measured by FTIR-ATR, was used to estimate the fraction of hydrogen-bonded carboxylic groups; this was ∼0.5 in PVPON/PMAA but only ∼0.1 in the PEO/PMAA system, though...

Overoxidized Polypyrrole/Cobalt Tetrasulfonated Phthalocyanine Modified Ultramicro‐Carbon‐Fiber Electrodes for the Electrooxidation of 2‐Mercaptoethanol

We report on the catalytic electrooxidation of 2-mercaptoethanol on ultramicro-carbon-fiber electrode (UMCF) modified with overoxidized polypyrrole-doped cobalt-tetrasulfonated phthalocyanine (CoTSPc) film. The easily prepared electrodes are stable and do not passivate after repetitive use. The sensitivity of the modified UMCF electrode towards the amperometric detection of 2-mercaptoethanol was tested with differential pulse voltammetry (DPV) and differential normal pulse amperometry (DNPA). A calculated detection limit as low as 8610 ˇ5 M was obtained by DPV. Our results show that UMCF electrodes are promising for the detection of low concentrations of thiols as mass transport limitations are minimized. The detection of thiol-derivated substances is an important field of research as they can be present as contaminants in fuels (1) and biological fluids (2) and they may be useful as markers of food deterioration (3, 4). During the last decade, several authors (5-17) have reported the catalytic electrooxidation of various thiols on electrodes modified with metallophthalocyanines. In general, electrodes of this type can be used as sensors (15-25) and various configurations have been developed such as carbon paste (15-17) and screen-printed carbon electrodes (19-25) containing cobalt phthalocyanines and derivatives. The advantage of the reported cobalt phthalocyanine-based electrodes is that the thiols (namely 2-mercaptoethanol, L-cysteine, reduced gluthathione etc.) can be monitored at considerable lower potentials compared with the nonmodified electrodes. Superior selectivity and sensitivity were also achieved. We and others have reported that much advantage can be obtained from the activity of cobalt phthalocyanines if they are electropolymerized forming conductive films that coat an electrode surface (14, 18), or if they are dispersed within a conductive polymeric matrix (12, 13). In addition, such an approach should allow the conception of various shapes and geometrical designs of electrode surfaces and a better control of their modification. In this work, we combine for the first time the use of electrochemically formed polypyrrole-doped cobalt tetra- sulfonated phthalocyanine (CoTSPc) with ultramicro-carbon-fiber electrode configuration (UMCF) to achieve the electrocatalytic oxidation of 2-mercaptoethanol (2-ME) in alkaline aqueous solu- tion and provide a miniaturized electrochemical sensor that is easily fabricated from low cost materials, providing an ultramicroprobe that may be developed for applications in biological systems. We have selected 2-ME as the examined analyte target since its elec- potential scan between ˇ0.2 and 0.7 V, at room temperature, starting at the lower potential limit. The incorporation of CoTSPc within the polypyrrole matrix (PPy) is based on the ion exchange properties of the oxidized polymer (26): the multianionic tetra- sulfonated cobalt phthalocyanine molecules are introduced into polypyrrole film as counterions (or ''doping'' ions) during the electrochemical growth of the polymer matrix. Note that in this operation, only CoTSPc was used as supporting electrolyte. The obtained film is denoted as PPy=CoTSPc. In order to avoid having a large electrical charge in the potentiodynamic response of the polypyrrole-based electrodes which creates a large background current that hinder the characterization of the electrocatalytic effects of the complex, the polymer was overoxidized by succes- sive potential scans betweenˇ0.2 and 0.4 V in 0.1 M NaOH (in the absence of pyrrole monomers) until the total suppression of its electroactivity. The obtained modified UMCF electrode is then denoted as OPPy=CoTSPc. In general, these electrodes are much more stable than those obtained by simple adsorption of phtha- locyanine monolayers on carbon or graphite surfaces since the

Tailorable Rectification: A study of Vertical Transport in AlGaN/GaN Heterostructures

In this paper, we report calculations that show that a metal-polar semiconductor heterostructure can exhibit highly controllable non-linear current-voltage (I-V) characteristics. Change in barrier thickness can alter the characteristics from Schottky-like to ohmic in different bias regimes. The origin of these unusual effects is a large electric field (> 106 V/cm) and high sheet charge (∼1013 – 1014 cm-2) without doping, in the polar heterostructure. Theoretical calculation of the tunneling current density in these systems indicates that very interesting non-linear behaviour is shown by theseystems, ev en in the undoped case. Choice of suitable compositions of the materials and thicknesses can be used to tailor devices with desired characteristics.

Thermodynamics of Kerr-Newman-AdS black holes and conformal field theories

We study the thermodynamics of four-dimensional Kerr-Newman-AdS black holes both in the canonical and the grand-canonical ensemble. The stability conditions are investigated, and the complete phase diagrams are obtained, which include the Hawking-Page phase transition in the grand-canonical ensemble. In the canonical case, one has a first-order transition between small and large black holes, which disappears for a sufficiently large electric charge or angular momentum. This disappearance corresponds to a critical point in the phase diagram. Via the AdS/CFT conjecture, the obtained phase structure is also relevant for the corresponding conformal field theory living in a rotating Einstein universe, in the presence of a global background U(1) current. An interesting limit arises when the black holes preserve some supersymmetry. These BPS black holes correspond to highly degenerate zero-temperature states in the dual CFT, which lives in an Einstein universe rotating with the speed of light.

Electric double-layer capacitor using composites composed of phosphoric acid-doped silica gel and styrene–ethylene–butylene–styrene elastomer as a solid electrolyte

Solid state electric double-layer capacitors have been fabricated using a composite composed of H 3 PO 4 -doped silica gel and styrene–ethylene–butylene–styrene elastomer as the electrolyte. A composite hybridized with activated carbon powders (ACP) was the polarizable electrode. The cyclic voltammogram of the electric double-layer capacitor fabricated demonstrated that electric charge was stored in the electric double-layer at the interface between the polarizable electrode and the electrolyte. Resistance of the capacitor obtained from impedance plots in ambient air was smaller by three orders of magnitude than that of the capacitor in a dry Ar atmosphere. The drastic decrease in the resistance should be ascribed to the increase in the proton conductivity of the composite due to the water adsorption in H 3 PO 4 -doped silica gel in an ambient atmosphere. The value of capacitance of the capacitor in an ambient atmosphere was 10 F/(gram of total ACP), which was 10 times larger than that of the capacitor in a dry Ar atmosphere. The large capacitance of the capacitor in an ambient atmosphere is attributable to the formation of electric double-layer with large electric charge at the interface between the composite and ACP in the capacitor due to the water adsorption.

Generation of low‐frequency electric fields by explosion crater formation

A low‐frequency electric field is observed during crater formation by detonation of high explosive charges. The disturbance of the atmosphere's electric potential gradient at ground level was measured in the range of frequencies between 0 and 200 Hz. Our results indicate that explosions are capable of creating large electrical charge separations in the atmosphere. A simple model of field generation is proposed. Furthermore, a correlation between the magnitude of the explosion and the electric charge of the dust cloud is established. Using these results, estimates of the intensity of the electric field generated during meteorite impact crater formation is proposed.

Electric Fields and Charges near 0°C in Stratiform Clouds

Earlier studies of mesoscale convective system stratiform regions have shown that large electric fields and charge densities are found near the 0°C level. Here 12 soundings of the electric field were analyzed through the 0°C level in various types of electrified stratiform clouds. For each electric field sounding, the thermodynamic sounding and supporting radar data were also studied. For comparison, five soundings not from stratiform clouds were included. Charge densities were found at or near 0°C in the stratiform clouds of at least 1 nC m−3 in eight of the soundings, and four of those had charge densities of at least 2 nC m−3. Of the stratiform soundings, 11 had an electric field magnitude of greater than 50 kV m−1 near 0°C, and 7 of those had an electric field magnitude of at least 75 kV m−1. The evidence suggests that melting may be the primary cause of the charge density found at and below 0°C in electrified stratiform clouds. In all 12 of the stratiform soundings, positive charge density was found at or near 0°C, and 11 of those had weaker negative charge density below. The evidence further suggests these two features do not exist in the absence of a bright band and (usually) an associated quasi-isothermal layer.

Random anisotropy in the Co2TiO4 compound

From previous magnetization measurements the assumed paramagnetic to ferrimagnetic transition temperature of Co2TiO4 is 55 K while the specific heat shows an anomaly at 49 K. New magnetization measurements show a magnetic transition of the random anisotropy kind at 48 K. The random anisotropy is assumed to arise from random lattice distortions screening large electric charge fluctuations due to the large charge difference between Co2+ and Ti4+.

Properties of II–VI semiconductors associated with moving dislocations

Abstract Moving dislocations in II–VI semiconductors carry a large electric charge. This charge is not in thermal equilibrium, but is due to the sweeping up of electrons from point defects. Its movement produces a dislocation current during plastic deformation, and conversely, the application of an external field changes the flow stress. This paper reviews the structure and properties of these dislocations, the theory of their charge and the phenomena which are a consequence of the strong mutual interactions of the dislocation and electronic sub-systems in these crystals. The materials show a large photoplastic effect (a change in flow stress under illumination), and related effects due to the injection of electrons at an electrode. Deformation produces reversible changes in the conductivity, pulsed and continuous luminescence and the emission of electrons from the surface.

Piezoelectric Gauge for Measurement of Pin and Socket Connector Contact Forces

The need for a convenient means of measurement of the actual contact force for a pin and socket connector is outlined and the design of a piezoelectric strain gauge suitable for use with in-line connectors is described. PZT is used for the strain sensitive element of the gauge, and the relatively large electric charges produced by small strains permit the use of a very simple electrical circuit. With sufficient experimental care, variations in contact force for different sockets of a given type may be correlated with variations in contact resistance.