Electric Charge Flow Research Articles

Direct‐Current Triboelectric Nanogenerator Realized by Air Breakdown Induced Ionized Air Channel

AbstractThe air breakdown phenomenon is generally considered as a negative effect in previous research on triboelectric nanogenerators (TENGs), which is always accompanied by air ionization. Here, by utilizing the air breakdown induced ionized air channel, a direct‐current triboelectric nanogenerator (DC‐TENG) is designed for harvesting contact‐separation mechanical energy. During working process, the charges first transfer from bottom to top electrodes through an external circuit in contact state, then flow back via the ionized air channel created by air breakdown in the separation process. So a unidirectional flow of electrical charges can be observed in the external circuit. With repeating contact‐separation cycles, continuous pulsed DC output through the external circuit can be realized. This working mechanism was verified by real‐time electrode potential monitoring, photocurrent signal detection, and controllable discharging observation. The DC‐TENG can be used for directly and continuously charging an energy storage unit and/or driving electronic devices without using a bridge rectifier. Owing to its simplicity in structure, the mechanism is further applied to fabricate the first flexible DC‐TENG. This research provides a significant fundamental study for DC‐TENG technology and may expand its application in flexible electronics and flexible self‐charging power systems.

Excitation of coherent propagating spin waves by pure spin currents.

Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1202-y) contains supplementary material, which is available to authorized users.

전하이동을 시각화한 PhET 기반 수업을 통한 초등과학영재의 전류개념변화

전하이동을 시각화한 PhET 기반 수업을 통한 초등과학영재의 전류개념변화

Ab initio electron propagator calculations of transverse conduction through DNA nucleotide bases in 1-nm nanopore corroborate third generation sequencing

BackgroundThe conduction properties of DNA molecule, particularly its transverse conductance (electron transfer through nucleotide bridges), represent a point of interest for DNA chemistry community, especially for DNA sequencing. However, there is no fully developed first-principles theory for molecular conductance and current that allows one to analyze the transverse flow of electrical charge through a nucleotide base. MethodsWe theoretically investigate the transverse electron transport through all four DNA nucleotide bases by implementing an unbiased ab initio theoretical approach, namely, the electron propagator theory. ResultsThe electrical conductance and current through DNA nucleobases (guanine [G], cytosine [C], adenine [A] and thymine [T]) inserted into a model 1-nm Ag–Ag nanogap are calculated. The magnitudes of the calculated conductance and current are ordered in the following hierarchies: gA>gG>gC>gT and IG>IA>IT>IC correspondingly. The new distinguishing parameter for the nucleobase identification is proposed, namely, the onset bias magnitude. Nucleobases exhibit the following hierarchy with respect to this parameter: Vonset(A)<Vonset(T)<Vonset(G)<Vonset(C). ConclusionsThe difference in current magnitudes and onset voltages implies the possibility of nucleobases electrical identification by virtue of DNA translocation through an electrode-equipped nanopore. General significanceThe results represent interest for the theorists and practitioners in the field of third generation sequencing techniques as well as in the field of DNA chemistry.

An Entropy Approach to the Natures of the Electric Charge and Magnetic Flux

As a result of investigating analytically and experimentally the interchangeability between thermal, electrical and magnetic energies, it is proved in the presented study that the electric and magnetic energies have an equivalent grade and nature as the thermal energy. So, the natural flow of electric charges and magnetic flux is associated also by increase of entropy of universe, similar to the heat, and has the same nature of waves as the electromagnetic heat radiation. Casting the Maxwell’s wave equation into an energy frame of reference that replaces the time in wave equations by entropy, it is possible to represent the electric charges and magnetic flux as electromagnetic waves of electric and magnetic potentials. Such results lead to modify exclusively the definition of the physical nature of the electric charge and magnetic flux which is unavailable in literature.

Simulation Analysis of Tilted Polyhedron-Shaped Thermoelectric Elements

The generation of thermoelectricity is considered a promising approach to harness the waste heat generated in industries, automobiles, gas fields, and other man-made processes. The waste heat can be converted to electricity via a thermoelectric (TE) generator. In this light, the generator performance depends on the geometric configuration of its constituent elements as well as their material properties. Our previous work reported TE behaviors for modules consisting of parallelogram-shaped elements, because elements with tilted laminate structures provide increased mechanical stability and efficient heat-transferring ability from the hot surface to the cold surface. Here, we study TE elements in the shape of a polyhedron that is obtained by mechanically truncating the edges of a parallelogram element in order to further enhance the generator performance and reduce TE material usage. The TE performance of the modules consisting of these polyhedron elements is numerically simulated by using the finite-volume method. The output power, voltage, and current of the polyhedral TE module are greater than those of the parallelogram-element module. The polyhedron shape positively affects heat transfer and the flow of electric charges in the light of increasing the efficiency of conversion from heat to electricity. By varying the shape of the truncated portions, we determine the optimal shape that enables homogeneous heat flux distribution and slow diffusion of thermal energy to obtain the better efficiency of conversion of heat into electricity. We believe that the findings of our study can significantly contribute to the design policy in TE generation.

Modelling and quantification of the thermoregulatory responses of the developing avian embryo: Electrical analogies of a physiological system

Homeothermic animals, including birds, try to keep their body temperature at a constant level within certain boundaries by using thermoregulatory mechanisms. However, during incubation, the thermoregulatory system of the chicken embryo evolves through different stages from a poikilothermic to a homeothermic system. Hence, the thermal response of the fertile egg to changes in ambient temperature is different from one day to another during the embryonic development. The incubated egg can be considered as a physical (thermal) system, which transfers energy (heat) down a potential gradient (temperature difference). The heat flow between the micro-environment and the eggshell under a thermal driving force (temperature difference) has been studied in the past by using the analogy to the flow of electric charge under an electromotive-force. In this work, the thermal-response of incubated eggs to a step-increase in ambient-air temperature is studied and modelled. It is shown that the incubated egg is reacting as a first-order system between embryonic days ED01 and ED13, while, starting from ED14, the egg is reacting as a second-order system. This extends the existing RC (resistor–capacitor) circuit analogue to an RLC (resistor–inductor–capacitor) circuit analogue at the later stage of incubation. The concept of considering the fertile egg and its surrounding environment as an energy-handling device is introduced in this paper. It is suggested that the thermoregulation of the embryo has a thermal induction-like effect starting from ED14 and increasing gradually till hatching.

Polydispersity-driven topological defects as order-restoring excitations.

The engineering of defects in crystalline matter has been extensively exploited to modify the mechanical and electrical properties of many materials. Recent experiments on manipulating extended defects in graphene, for example, show that defects direct the flow of electric charges. The fascinating possibilities offered by defects in two dimensions, known as topological defects, to control material properties provide great motivation to perform fundamental investigations to uncover their role in various systems. Previous studies mostly focus on topological defects in 2D crystals on curved surfaces. On flat geometries, topological defects can be introduced via density inhomogeneities. We investigate here topological defects due to size polydispersity on flat surfaces. Size polydispersity is usually an inevitable feature of a large variety of systems. In this work, simulations show well-organized induced topological defects around an impurity particle of a wrong size. These patterns are not found in systems of identical particles. Our work demonstrates that in polydispersed systems topological defects play the role of restoring order. The simulations show a perfect hexagonal lattice beyond a small defective region around the impurity particle. Elasticity theory has demonstrated an analogy between the elementary topological defects named disclinations to electric charges by associating a charge to a disclination, whose sign depends on the number of its nearest neighbors. Size polydispersity is shown numerically here to be an essential ingredient to understand short-range attractions between like-charge disclinations. Our study suggests that size polydispersity has a promising potential to engineer defects in various systems including nanoparticles and colloidal crystals.

Exploring electrical conductivity within mesoscopic phases of semiconducting poly(3,4-ethylenedioxythiophene):poly(4-styrene-sulfonate) films by broadband dielectric spectroscopy

Poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonate) (PEDOT:PSS), an optically transparent organic semi-conductor, constitutes a suspension of conducting PEDOT:PSS grains, shelled by an insulating layer of PSS. While a percolation network enhances dc conductivity, structural and electrical inhomogeneity hinters electric charge flow giving rise to capacitance effects. In the present work, two distinct relaxation mechanisms are detected by Broadband Dielectric Spectroscopy. Double polarization mechanisms are predicted by bi-phase suspension dielectric theory. Within the frame of interfacial polarization, we propose a methodology to have an insight into the local conductivity of the interior of mesoscopic conducting phase.

Strongly correlated quantum spin liquid in herbertsmithite

Strongly correlated Fermi systems are among the most intriguing and fundamental systems in physics. We show that the herbertsmithite ZnCu3(OH)6Cl2 can be viewed as a new type of strongly correlated electrical insulator that possesses properties of heavy-fermion metals with one exception: it resists the flow of electric charge. We demonstrate that herbertsmithite's low temperature properties are defined by a strongly correlated quantum spin liquid made with such hypothetic particles as fermionic spinons which carry spin 1/2 and no charge. Our calculations of its thermodynamic and relaxation properties are in good agreement with recent experimental facts and allow us to reveal their scaling behavior which strongly resembles that observed in heavy-fermion metals. Analysis of the dynamic magnetic susceptibility of strongly correlated Fermi systems suggests that there exist at least two types of its scaling.

Self calibration of a planar dissolved oxygen sensor

Abstract A poor long-term stability of planar microscaled oxygen sensors appears to have prevented their widespread use. This investigation study reports on an approach to enable a continuous long term operation of such sensors by in situ self-calibration. This involves a controlled anodic electrolysis of ambient water to generate an additional amount of dissolved oxygen spreading by diffusion. The response of the cathodic detecting electrode, i.e. the actual oxygen sensor, in relation to the additional oxygen spike is a measure of its sensitivity and the basis for calculating a correction factor. Generating and detecting electrodes are operated sequentially under non-steady-state conditions. In order to test the method, the quality of the corrected sensor signal output versus the uncorrected signal is tested by comparison with a benchmark optosensor signal. The approach is applicable as long as Faraday's relationship between electric charge flow and amount of oxygen generated is valid. The data indicate that an enhancement of a planar oxygen sensor's signal output by the self-calibration procedure can be achieved.

Lattice Boltzmann Model for Simulation of the Electric Charge Flow and Calculation of Electrorheology

Lattice Boltzmann Model for Simulation of the Electric Charge Flow and Calculation of Electrorheology

A Thermodynamic Analysis of Energy Flow in Optical Fiber Communication Systems

A thermodynamic analysis of energy flow in different elements of an optical fiber communication system is presented. The analysis depends on a previously introduced entropy approach that postulated the flow of electric charges as a flow of electromagnetic waves. Such a postulate is introduced here to find a plausible explanation of the electro-optic Kerr effect. Following the same approach, the transmitter and receivers of the optical communication-systems are explained according to measurement results as converters of electric waves into light waves or converters of light waves into electric waves. Similarly, pumping of optical energy or electrical energy into the elements of a communication system is found equivalent to pumping of entropy. Such results are introduced to derive energy equations that model the flow of energy and different processes in an optical communication-system. The introduced approach that depends on the postulated definition of electric current is compared to a classical approach in an analysis of energy flow into 80 MHz fiber laser.

Computing by physical interaction in neurons

The electrodynamics of action potentials represents the fundamental level where information is integrated and processed in neurons. The Hodgkin-Huxley model cannot explain the non-stereotyped spatial charge density dynamics that occur during action potential propagation. Revealed in experiments as spike directivity, the non-uniform charge density dynamics within neurons carry meaningful information and suggest that fragments of information regarding our memories are endogenously stored in structural patterns at a molecular level and are revealed only during spiking activity. The main conceptual idea is that under the influence of electric fields, efficient computation by interaction occurs between charge densities embedded within molecular structures and the transient developed flow of electrical charges. This process of computation underlying electrical interactions and molecular mechanisms at the subcellular level is dissimilar from spiking neuron models that are completely devoid of physical interactions. Computation by interaction describes a more powerful continuous model of computation than the one that consists of discrete steps as represented in Turing machines.

Comments on Einstein’s Explanation of Electrons, Photons, and the Photo-Electric Effect

According to an entropy approach and by reviewing the similarity between laws characterizing the flow of heat and electric charges, electric charges were defined as electromagnetic waves that possess an electrical potential or simply as ionized photons. Accordingly, the flow of electrons was defined as a simultaneous flow of particulate energy and wave energy. Such definitions led to clear the confusions of duality properties of electrons and light waves, conflicts in the SI system of units and to explain the difference between the calculated drift speed of electrons and the speed of electricity or charges in conductors. However, Einstein considered the electron to be a negative charge of unknown nature during his analysis of the photoelectric effect. Einstein presented his hypothesis that light may behave as a particle to find a plausible explanation of the photoelectric effect. He found the measured cutoff frequency of light below which light might not eject electrons from metal-surfaces in photocells regardless of how much light is shone on the surface as a proof of truth of his hypothesis. Such frequency may be explained also, according to the previously introduced definitions, as the minimum energy quanta that may gain a quantized potential in photocells. This explanation may find plausible explanations of the found measurements of the photoelectric effects for different metal surfaces, stopping voltages into photocells and the photoelectric effect of X-rays. Einstein’s hypothesis of the photoelectric effect failed to find plausible explanations of such measurement results. According to the principles of conservation of momentum, there is a minimum quantity of photons that may lead to bouncing an atomic electron out of its orbit. So, considering Einstein’s theory as a perfect hypothesis that explains the photoelectric effect may be a misconception.

Analyzing the Duality Concept through an Entropy Approach

According to a previously introduced entropy approach; the flow of electric charges was defined as a flow of electromagnetic waves that has an electric potential. Similarly; the magnetic flux was defined as a flow of electromagnetic waves that has a magnetic potential. By a similar entropy approach, particle's kinetic energy is defined also as electromagnetic waves. So: the electron can be defined as an energized particle whose electric charge, magnetic energy and kinetic energy are electromagnetic waves. According to such definition and to the found similarity of the mechanisms and laws of mass and energy diffusions in additions to the Einstein’s principle of mass-energy equivalence; the flow ofelectrons can be postulated as a simultaneous flow of two energy components; particulized energy and wave energy. Hence; the electron hasn’t a dual nature but its behavior as a particle or as wave depends on the relative values of its two components in each flow. Truth of the introduced postulates is proved through finding also plausible explanation of thesintering phenomena and de-Broglie hypothesis.

Effect of pore structure on electrical resistivity in carbonates

The electrical resistivity log has proven to be a powerful tool for lithology discrimination, correlation, porosity evaluation, hydrocarbon indication, and calculation of water saturation. Carbonate rocks develop a variety of pore types that can span several orders of magnitude in size and complexity. A link between the electrical resistivity and the carbonate pore structure has been inferred, although no detailed understanding of this relationship exists. Seventy-one plugs from outcrops and boreholes of carbonates from five different areas and ages were measured for electrical resistivity properties and quantitatively analyzed for pore structure using digital image analysis from thin sections. The analysis shows that in addition to porosity, the combined effect of microporosity, pore network complexity, pore size of the macropores, and absolute number of pores are all influential for the flow of electric charge. Samples with small pores and an intricate pore network have a low cementation factor, whereas samples with large pores and a simple pore network have high values for cementation factor. Samples with separate-vug porosity have the highest cementation factor. The results reveal that (1) in carbonate rocks, both pore structure and the absolute number of pores (and pore connections) seem more important in controlling the electrical resistivity, instead of the size of the pore throats, as suggested by previous modeling studies; (2) samples with high resistivity can have high permeability; large simple pores facilitate flow of fluid, but fewer numbers of pores limit the flow of electric charge; and (3) pore-structure characteristics can be estimated from electrical resistivity data and used to improve permeability estimates and refine calculations of water saturation.

An Entropy-Approach to the Duality Property

According to a previously introduced entropy approach, it is possible to clarify the confusions of the duality concept that electrons and light may behave as waves or particles. In other words, the electron is clearly defined in this paper as a particle and the light is neatly defined as waves. Such an approach considered the flow of electric charges as a flow of ionized waves and the magnetic flux as electromagnetic waves of magnetic potential. By a similar entropy approach, the particle’s kinetic energy is defined also as electromagnetic waves. So, the electron can be defined as an energized particle whose electric charge, magnetic energy and kinetic energy are forms of electromagnetic waves. According to these definitions and similarity of the mechanisms and laws characterizing the flow of mass and energy in general, the flow of electrons can be postulated as a simultaneous flow of two energy-components; particulized energy and wave energy. Hence, the electron doesn’t have a dual nature. Rather, its behavior as a particle or as waves depends on the relative contributions of such components in the electron’s flow. Reviewing the results of de-Broglie’s experiments, it is possible to consider the flow of any particles as a simultaneous flow of waves and particles. Introducing the definition of the flow of electric charges as ionized waves, the photoelectric-effect can be postulated as an ionization process of the incident radiation during its reflection into an electric field. Similarly, the photovoltaic phenomena are postulated as a result of a photorefractive effect that may induce an electric potential into the incident radiation when crossing the electrically biased p-n junctions of photocells. Such postulates eliminate the confusing particle-property of light and prove that light has a wave-nature only. The truth of the introduced postulates is proven through finding plausible explanation of the sintering phenomena and thermoelectricity. Finally, this paper succeeded in introducing plausible explanations of results of Thompson’s experiment and other phenomena that end the confusions in defining the true nature of light and electrons as waves and particles.

Vibrational and electronic heating in nanoscale junctions

Understanding and controlling the flow of heat is a major challenge in nanoelectronics. When a junction is driven out of equilibrium by light or the flow of electric charge, the vibrational and electronic degrees of freedom are, in general, no longer described by a single temperature. Moreover, characterizing the steady-state vibrational and electronic distributions in situ is extremely challenging. Here, we show that surface-enhanced Raman emission may be used to determine the effective temperatures for both the vibrational modes and the electrons in the current in a biased metallic nanoscale junction decorated with molecules. Molecular vibrations show mode-specific pumping by both optical excitation and d.c. current, with effective temperatures exceeding several hundred kelvin. Anti-Stokes electronic Raman emission indicates that the effective electronic temperature at bias voltages of a few hundred millivolts can reach values up to three times the values measured when there is no current. The precise effective temperatures are model-dependent, but the trends as a function of bias conditions are robust, and allow direct comparisons with theories of nanoscale heating.