Electric Current Changes Research Articles

Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

A Comparative Study of Unsaturated Resin/Graphite Microchip and Nano-Graphite Microchip Composites Prepared by Electric Field

Graphite microsheets as conductive fillers have their unique advantages compared with a traditional conductive fillers such as carbon black. Graphite microsheets have a large diameter-thickness ratio, which greatly reduces the percolation threshold of conductive composite system with graphite microsheets as conductive fillers. Under the action of applied electric field, the orientation of graphite microsheets in polymers changes the distribution of graphite in polymers. The conductivity of the composites can be changed. Because of the large diameter-thickness ratio, the nanographite microchip is easier to form conductive pathways in the composites. It can be imagined that the conductivity of ordinary graphite nanosheets can be achieved at a lower content as the ultra-fine dispersed graphite nanosheets. With the use of the conductive materials stated above and through the effect of applied electric field, we were able to get a new method of processing materials and functional materials with a higher design and better comprehensive performance. As conductive fillers, graphite nanosheets can be induced by the AC electric field in unsaturated polyester resin and then prepared oriented unsaturated polyester resin/graphite nanosheets composite. Compared with one-dimensional structure of carbon nanofiber and carbon nanotubes, two-dimensional lake-like shape graphite nanosheets have high aspect ratio. Applying an electric field during the preparation of the composite, graphite nanosheets can be oriented conquering the shearing action of viscous in an insulating polymer matrix due to the cooperative effect of the electric torque exerted by the electric field directly on the nanosheets. Finally, through the change of electric current of composite materials prepared in different media under electric field, we determine the influence factors of conductivity of composite materials and the conductive mechanism of nano-graphite micro-sheets under electric field.

Parameterization of In‐Cloud Aerosol Scavenging Due to Atmospheric Ionization: Part 4. Effects of Varying Altitude

AbstractWe have verified that the modified analytic solution (MAS) for aerosol scavenging designed in our previous work to parameterize in‐cloud collision rate coefficients between aerosol particles and droplets can be extended to altitudes ranging from 0 to 20.6 km, and droplet radii up to 100 μm. The MAS deals separately with the short‐range effects and long‐range effects involved in the collisions, with the short‐range effects including image electric forces, the intercept effect, and the weight effect; and the long‐range effects including Brownian diffusion, the Coulomb electric force, and phoretic forces. The effects of Brownian diffusion and Coulomb electric force increase as height increases, while the change of phoretic forces with altitude is complicated. The effects of image electric force and intercept change slightly with altitude, while the weight effect increases significantly at higher altitudes. When the short‐range effects include the irregular shape of particles, the MAS also works well. The calculations of collision rate coefficients by our Monte Carlo trajectory model for varying droplet radius, droplet charges, particle radius, particle charges, particle density, relative humidity, pressure and temperature have now been completed, and we parameterize them by the simple MAS method which makes the results user friendly and easily applicable for cloud models. Based on our results, it is now possible to build cloud models to investigate the hypothesized link between the downward current flow in the global electric circuit current and cloud microphysical changes affecting cloud development.

Designing of an ultrasensitive BCM-7 aptasensor based on an SPCE modified with AuNR for promising distinguishing of autism disorder

Abstractly, in this study, an aptasensor is introduced based on a platform consisting of the gold nanorod (AuNR) on a screen printed carbon electrode (SPCE) surface. The aptasensor is applied for detection of the β-casomorphin (BCM-7) as a promising biomarker of autism disorder. The NH2-Apt sequence is directly immobilized onto the AuNR/SPCE surface by formation of a chemisorption bond between the amine-Au groups. By incubation of the BCM-7 onto the aptasensor surface, the aptasensor directed against BCM-7 and cleverly formed a target/Apt complex to produce a measurable electrical current change. The aptasensor shows linearity over the range of 1 fmol L−1 to 25 nmol L−1 with a limit of detection (LOD) of 334 amol L−1. Furthermore, the function of the aptasensor in real samples such as human urine and plasma samples is evaluated. The achieved satisfactory results are mainly due to three main reasons including (1) the large specific surface area of the AuNR which forms a 3D network on the SPCE surface to capture more Apt sequences at the sensing interface, (2) utilizing Apt as the BCM-7 receptor with inherent unique properties to produce a synergetic effect with the AuNR, and finally, (3) effective using screen printing technology with the fantastic capability to less cost of the aptasensor preparation. There is hope that miniaturization of the proposed aptasensor may aid future efforts to detect autism symptoms as early as infancy under clinical conditions in real-world.

The Plasma Nature of Lightning Channels and the Resulting Nonlinear Resistance

AbstractLightning channels are made of plasma. As a consequence, the driving electrical current changes the channel's resistance in a nonlinear fashion. The resistance has an intricate dependence on the history of Joule heating and various cooling processes, as well as on the various kinetic processes that dictate the population balance of electrons within the channel. Such dependence cannot be captured by an analytic function, as often attempted. In this paper, we introduce a minimal numerical model that can qualitatively capture the temporal dynamics of the key plasma properties of a lightning channel, including its electric field, temperature, plasma density, radius, and the resulting nonlinear resistance. Through a series of novel parameterizations, we introduce six zero‐dimensional equations that can capture both nonequilibrium/low‐temperature and local thermodynamic equilibrium/high‐temperature plasma regimes. In this manuscript, we go to great lengths to validate the model, showing that it can reproduce the finite time scale of streamer‐to‐leader transition, replicate the negative differential resistance behavior of steady‐state plasma arcs, and properly describe the temporal evolution of temperature in a return stroke channel. Finally, the model is applied to the simulation of optical emissions from rocket‐triggered lightning strikes, explaining the measured delay between the rise of current and visible light, as well as reproducing the direct relationship between peak current and peak radiated power and between charge transferred to ground and total radiated energy.

Simulation and experimental study of FET biosensor to detect polycyclic aromatic hydrocarbons

Abstract In this paper, the DNA/Cu2O-GS nanostructure was simulated to detect polycyclic aromatic hydrocarbons (PAHs) and compared with our experimental results. We use a simulation for calculations based on density functional theory (DFT). In the first step, DNA/Cu2O-GS nanostructure was simulated and adsorption mechanism, the density of states and charge transfer process were investigated in the presence and absence of PAHs using the QUANTUM ESPRESSO software and BoltzTrap computing code. The simulation results showed that Cu2O-GS nanostructure can be well used to adsorption and stabilization of DNA. Also the simulation results of electrical conductivity change showed that DNA/Cu2O-GS nanostructure can be well used as a field effect transistor (FET) to detect PAHs. On the other hand, the electric current changes of the DNA/Cu2O-GS-FET for three samples of PAHs (benzene, toluene, and naphthalene) were experimentally studies. Also current leakage, the sensitivity, and dynamic range of transistor for benzene, naphthalene and toluene experimentally were investigated. The experimental results show that the DNA/Cu2O-GS-FET can use as a biosensor for PAHs. Our simulation and experimental results are in good agreement and this DFT-based simulation idea can use for other biosensors.

Electroceutical Residue-Free Graphene Device for Dopamine Monitoring and Neural Stimulation.

The simultaneous neural signal monitoring and stimulation can allow accurate neurotransmitter regulation for patients in various degrees of neural degeneration disorders. Here, we developed a residue-free graphene device as an effective electrical neural interface for dopamine sensing and secretion. We demonstrated the ultrasensitive dopamine sensing of residue-free graphene devices cultured with PC12 cells and the on-demand functional electrical stimulation for electroceutical applications. The doping effect of graphene by the released dopamine from living cells was confirmed from the electrical current change. The dopamine release could be also quantitatively analyzed by ELISA. Then, Ca2+ ion-dependent dopamine release was optically observed by fluorescence microscopy during the stimulation. Taken together, this study confirms the feasibility of graphene surface as a neural interface for electroceutical applications to various central nerve system disorders.

Electroluminescence on-off ratio control of n−i−n GaAs/AlGaAs-based resonant tunneling structures

We explore the nature of the electroluminescence (EL) emission of purely n-doped GaAs/AlGaAs resonant tunneling diodes (RTDs) and the EL evolution with voltage. A singular feature of such a device is unveiled when the electrical output current changes from high to low and the EL on-off ratio is enhanced by 2 orders of magnitude compared to the current on-off ratio. By combining the EL and current properties, we are able to identify two independent impact ionization channels associated with the coherent resonant tunneling current and the incoherent valley current. We also perform the same investigation with an associated series resistance, which induces a bistable electrical output in the system. By simulating a resistance variation for the current-voltage and the EL, we are able to tune the EL on-off ratio by up to 6 orders of magnitude. We further observe that the EL on and off states can be either direct or inverted compared to the tunneling current on and off states. This electroluminescence, combined with the unique RTD properties such as the negative differential resistance (NDR) and high frequency operation, enables the development of high speed functional opto-electronic devices and optical switches.

Preliminary Study on Biosensor-Type Time-Temperature Integrator for Intelligent Food Packaging.

A glucose biosensor was utilized as a platform for the time-temperature integrator (TTI), a device for intelligent food packaging. The TTI system is composed of glucose oxidase, glucose, a pH indicator, and a three-electrode potentiostat, which produces an electrical signal as well as color development. The reaction kinetics of these response variables were analyzed under isothermal conditions. The reaction rates of the electrical current and color changes were 0.0360 ± 0.0020 (95% confidence limit), 0.0566 ± 0.0026, 0.0716 ± 0.0024, 0.1073 ± 0.0028 µA/min, and 0.0187 ± 0.0005, 0.0293 ± 0.0018, 0.0363 ± 0.0012, 0.0540 ± 0.0019 1/min, at 5, 15, 25, and 35 °C, respectively. The Arrhenius activation energy of the current reaction (Eacurrent) was 25.0 ± 1.6 kJ/mol and the Eacolor of the color reactions was 24.2 ± 0.6 kJ/mol. The similarity of these Ea shows agreement in the prediction of food qualities between the electrical signal and color development. Consequently, the function of the new time-temperature integrator system could be extended to that of a biosensor compatible with any electrical utilization equipment.

Effects of internal electrode cooling on irreversible electroporation using a perfused organ model

Purpose: This study evaluates the effects of active electrode cooling, via internal fluid circulation, on the irreversible electroporation (IRE) lesion, deployed electric current and temperature changes using a perfused porcine liver model.Materials and methods: A bipolar electrode delivered IRE electric pulses with or without activation of internal cooling to nine porcine mechanically perfused livers. Pulse schemes included a constant voltage, and a preconditioned delivery combined with an arc-mitigation algorithm. After treatment, organs were dissected, and treatment zones were stained using triphenyl-tetrazolium chloride (TTC) to demonstrate viability.Results: Thirty-nine treatments were performed with an internally cooled applicator and 21 with a non-cooled applicator. For the constant voltage scenario, the average final electrical current measured was 26.37 and 29.20 A for the cooled and uncooled electrodes respectively (). The average final temperature measured was 33.01 and 42.43 °C for the cooled and uncooled electrodes respectively (). The average measured ablations (fixed lesion) were 3.88-by-2.08 cm and 3.86-by-2.12 cm for the cooled and uncooled electrode respectively (, ). Similarly, the preconditioned/arc-mitigation scenario yielded an average final electrical current measurement of a 41.07 and 47.20 A for the cooled and uncooled electrodes respectively (). The average final temperature measured was 34.93 and 44.90 °C for the cooled and uncooled electrodes respectively (). The average measured ablations (fixed lesion) were 3.67-by-2.27 cm and 3.58-by-2.09 cm for the cooled and uncooled applicators ().Conclusions: The internally-cooled bipolar applicator offers advantages that could improve clinical outcomes. Thermally mitigating internal perfusion technology reduced tissue temperatures and electric current while maintaining similar lesion sizes.

Magnetoreception of Photoactivated Cryptochrome 1 in Electrochemistry and Electron Transfer.

Cryptochromes are flavoproteins whose photochemistry is important for crucial functions associated with phototropism and circadian clocks. In this report, we, for the first time, observed a magnetic response of the cryptochrome 1 (CRY1) immobilized at a gold electrode with illumination of blue light. These results present the magnetic field-enhanced photoinduced electron transfer of CRY1 to the electrode by voltammetry, exhibiting magnetic responsive rate constant and electrical current changes. A mechanism of the electron transfer, which involves photoinduced radicals in the CRY, is sensitive to the weak magnetic field; and the long-lived free radical FAD•– is responsible for the detected electrochemical Faradaic current. As a photoreceptor, the finding of a 5.7% rate constant change in electron transfer corresponding to a 50 μT magnetic field may be meaningful in regulation of magnetic field signaling and circadian clock function under an electromagnetic field.

Oxidation of ß-SiC at high temperature in Ar/O2, Ar/CO2, Ar/H2O gas mixtures: Active/passive transition

An experimental study of the active/passive transition in the oxidation of ß-SiC was carried out between 1650 °C and 1800 °C in Ar/O2, Ar/H2O and Ar/CO2 gas mixtures or mixtures including two among these oxidant species. For that purpose an experimental device based on a Joule-heated SCS-6 fiber permitted determination of the oxidation regime from changes in electric current. The observed transitions were compared to results from other authors. Two predictive models of the active/passive transition were studied by means of a 3-D simulation of the experimental device in order to have an estimation of the volatilization rate of SiO2. These models were compared against experimental results.

Design of resonance based DC current sensor using BAW quartz resonators

A novel approach is attempted to measure DC current in the range of 0–0.7 A in this paper. The proposed current sensing system is designed using an AT-cut BAW quartz resonator sandwiched at the center of the rectangular beam. The SMA wire bonded over the rectangular beam changes its shape with the change in input current. The quartz crystal resonator is maintained at first mode resonance frequency using a closed loop resonator electronics. The electric current change in the SMA wire contracts its length which bends the beam and produces an axial force on the quartz resonator which changes the resonance frequency of the BAW crystal placed in between the beam. The shift in quartz crystal resonant frequency is related to the input electrical current in the SMA wire. The analytical model of the entire current sensing system is derived, and the proposed concept is verified experimentally. It is observed that the experimentation results are highly linear, and it has the sensitivity of 350 Hz/A DC current.

Time-Dependent Finite Element Analysis of In Vivo Electrochemotherapy Treatment.

Electrochemotherapy and irreversible electroporation are gaining importance in clinical practice for the treatment of solid tumors. For successful treatment, it is extremely important that the coverage and exposure time of the treated tumor to the electric field are within the specified range. In order to ensure successful coverage of the entire target volume with sufficiently strong electric fields, numerical treatment planning has been proposed and its use has also been demonstrated in practice. Most of numerical models in treatment planning are based on charge conservation equation and are not able to provide time course of electric current, electrical conductivity, or electric field distribution changes established in the tissue during pulse delivery. Recently, a model based on inverse analysis of experimental data that delivers time course of tissue electroporation has been introduced. The aim of this study was to apply the previously reported time-dependent numerical model to a complex in vivo example of electroporation with different tissue types and with a long-term follow-up. The model, consisting of a tumor placed in the liver with 2 needle electrodes inserted in the center of the tumor and 4 around the tumor, was validated by comparison of measured and calculated time course of applied electric current. Results of simulations clearly indicated that proposed numerical model can successfully capture transient effects, such as evolution of electric current during each pulse, and effects of pulse frequency due to electroporation effects in the tissue. Additionally, the model can provide evolution of electric field amplitude and electrical conductivity in the tumor with consecutive pulse sequences.

Linear correlation between pH value of stimulated beef and electrical current intensity

ABSTRACTThe aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.

Evaluation of Reflexology by "BIOCERAMIC Resonance" Operation producing Weak Force Field during Simultaneous Acupoint Stimulation of Urinary Bladder Point on Subject's Ear Resulting in Electric Current Change on Urinary Bladder reflex Point on Subject's Hands, and Related New Research Finding.

It was postulated in our previous publications that the meridian channels as conceived in Traditional Chinese Medicine (TCM) are various standing waves arising from harmonic rhythmic sound frequencies originating from the human heart beat. BIOCERAMIC is an artificial material able to produce a weak force field causing different biophysical and systemic health benefits, with the key characteristics of hydrogen bonds weakening and microcirculation enhancement. Since discovering that the effects of a BIOCERAMIC field can be transmitted via sound waves propagation, we then also developed a BIOCERAMIC Resonance device to produce weak force field throughout the body, and achieve resonance with the body's meridian channels to reinforce microcirculation. Since our previous research proved BIOCERAMIC can produces changes in ectodermal current levels, the present evaluation on reflexology is done by the application of Electric Current Detection (ECD) to the palmar surface of the hands matching correlative organs and glands loci to reflex points according to standard reflexology. The procedure will compare changes in the electrical current observed before and after a session of BIOCERAMIC Resonance treatment on the soles of the subjects' feet. We also conducted a procedure using corona discharge (Kirlian) photography of the hands to examine whether the coronal intensities could be affected by application of the BIOCERAMIC patch. Intensities are shown on the screen of a computer using special software that categorizes intensities into five zones. Under the continuous treatment of BIOCERAMIC Resonance on soles of the feet and simultaneous stimulation on the specific point on the surface of the ear representing the urinary bladder. The electrical current (Aji ampere) on the areas in the hands are decreased from the beginning of the experiment, but only the specific area on the surface of the ear representing the urinary bladder was exhibited increased of the electrical current (Aji ampere), with statistically significant difference (p<0.05). To the other study we evaluated the validity of reflexology and corona discharge (Kirlian) photography by applying BIOCERAMIC Resonance and small adhesive patches made from the BIOCERAMIC material. Significant differences were evident on four out of five different zones of the computerized images. Our findings suggest the existence of presupposed virtual channels or reflex points on the skin surface of the feet, hands, and ears that connect or somehow reflect back to specific internal organs, as mapped out on standard charts found in reflexology. Furthermore, the depicted corona intensities from five zones shown on a computer screen of corona discharge photography seem to indicate that the volunteer subjects are affected by the BIOCERAMIC patches. This study demonstrates the operation of the BIOCERAMIC Resonance device is able to produce weak force field through the body, which is objectively measurable and thereby scientifically integrating the concepts of reflexology, meridian channels and biofield therapy.

Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

It has been corroborated in the past that Pauli blockade mechanisms of weakly spin-coupled charge carrier pairs undergoing transitions into doubly occupied singlet states are among the most dominant spin-selection rules influencing room-temperature magnetoresistance and luminescence of organic semiconductors. It has remained unclear though whether these pairs consist of equal or opposite charges, and thus, whether the spin-dependent transitions are recombination or charge transport processes. Here, the authors report on simultaneous transient measurements of electric current and optical emission changes in organic light emitting diodes due to pulsed magnetic resonance induced charge carrier spin manipulation. When a room-temperature steady-state current is changed magnetic resonantly, the electroluminescence changes show identical dynamic and magnetic resonant signatures, indicating that both observables are controlled by the same spin-dependent electronic process. However, a quantitative analysis of the optical emission change reveals that its magnitude significantly exceeds what is expected from the magnitude of the electrical current change, implying that the optical emission change occurs not only because of the device current change but also due to a change of the radiative recombination rate, thereby showing that the observed spin-dependent process is due to recombination, not transport.

Study of Alcohol Sensing Devices Using DMFC Technology

Sensors for alcohols can be fabricated using Direct Methanol Fuel Cell (DMFC) technology. The designed and fabrication of the sensor is by means of micro electro mechanical systems (MEMS) fabrication technology with microfludic interconnects and with the electrochemical inputs using a standard DMFC cell arrangement. An amperometric detection technique will be employed. The accuracy will be determined by the accurate detection of electric current or changes in electric current. Using a passive mode design protocol in COMSOL Multiphysics, we have optimized the overall power density and hence the sensitivity of the sensor. This was achieved using various physical parametric functions, and interfacing Darcy’s law of fluidic flow through a porous medium, under specific pressure and temperature. This involved the fabrication of fluid flow diffusion layers using carbon matrix for electrodes. Pt-Sn was chosen as the Oxygen Reduction Reaction (ORR) catalysts. The cell outputs have been discussed.

Effect of wall thickness and helium cooling channels on duct magnetohydrodynamic flows

The concept of dual coolant liquid metal (LM) blanket has been proposed in different countries to demonstrate the technical feasibility of DEMO reactor. In the system, helium gas and PbLi eutectic, separated by structure grid, are used to cool main structure materials and to be self-cooled, respectively. The non-uniform wall thickness of structure materials gives rise to wall non-homogeneous conductance ratio. It will lead to electric current distribution changes, resulting in significant changes in the velocity distribution and pressure drop of magnetohydrodynamic (MHD) flows. In order to investigate the effect of helium channels on MHD flows, different methods of numerical simulations cases are carried out including the cases of different wall thicknesses, single pass of helium cooling channels, and three types of dual helium cooling channels. The results showed that helium tubes are able to affect the velocity distribution in the boundary layer by forming wave sharp which transfers from Hartmann boundary layer to the core area. In addition, the potential profile and pressure drop in the cases have been compared to these in the case of walls without cooling channel, and the pressure gradient of a simplified single short duct MHD flow in blanket shows small waver along the central axis in the helium channel position.

Differential microfluidic sensor on printed circuit board for biological cells analysis.

Coulter principal based resistive pulse sensor has been demonstrated as an important platform in biological cell detection and enumeration since several decades ago. Recently, the miniaturized micro-Coulter counter has attracted much attention due to its advantages in point of care diagnostics for on chip detection and enumeration of rare cells, such as circulating tumor cells. In this paper, we present a microfluidic cytometer with differential amplifier based on Coulter principle on a SU-8 coated printed circuit board substrate. The electrical current changes induced by the blockage of the microparticles in the sensing aperture are calibrated by polystyrene particles of standard size. Finally, HeLa cells are used to evaluate the performance of the proposed device for enumeration of biological samples. The proposed cytometer is built upon the cheap and widely available printed circuit board substrate and shows its great potential as personalized healthcare monitor.