Application Of Electric Voltage Research Articles

Detection of electrocatalytical and -chemical processes by means of in situ flow NMR spectroscopy

In situ studies of electrochemical processes using NMR offer valuable information on reaction mechanisms, kinetics, and species identification, making it a powerful tool in electrochemistry research. In this study, we present the design of an in situ redox-flow NMR cell that allows for a continuous flow of liquid (electrolyte) or gas, application of electrical voltage, and recording of NMR signals. The utility of this setup is demonstrated through two case studies: electrochemical copper deposition on a gold electrode and the electrochemical conversion of carbon dioxide into hydrocarbon products. Specifically, the presence of multicarbon products containing C–C bonds generated during the electrochemical reduction reaction is confirmed in the 2H NMR spectra in the latter example. These findings highlight the ability of the in situ redox-flow NMR cell to directly monitor reaction intermediates and products, thereby enabling the elucidation of reaction mechanisms for the efficient and selective production of valuable hydrocarbon products through the conversion of CO2 into value-added chemicals. In contrast to other reported in situ NMR cells, the presented cell is suitable for multiple uses, and allows detecting NMR signals not only from exhaust products but also from those formed on the catalyst surface.

Mode-I fracture control of unidirectional laminated composites using MFC actuators

This article presents an experimental and numerical investigation of Mode-I fracture control in aerospace grade unidirectional laminated composites (AS4/914) using the smart material approach. The P1 type macro fiber composites (MFC) actuators are selected for current research because of their higher free strain, high mechanical flexibility, and good blocking force. The opening mode (Mode-I) interlaminar fracture tests have been carried out on DCB specimens having surface bonded MFC actuator patches under the application of electric voltage within a range of 0–1500 V. These fracture control tests have been performed on pre-cracked (PC) and non pre-cracked (NPC) double cantilever beam specimens. The modified pin force model has been adopted for the evaluation of actuation forces in surface bonded MFC actuators. The XIGA-CZM based numerical formulation is utilized for numerical fracture modeling under electromechanical loading conditions. The MFC actuators have significant control over Mode-I fracture energy under the application of peak operating voltage. The numerical model using a modified pin force model in combination with XIGA-CZM based fracture model shows a good agreement with experimental observations.

Electric control of dielectric droplets and films

We investigate the behavior of dielectric droplets and films placed onto a solid surface under the action of electric field of different configurations. The mesoscopic thermal multiphase lattice Boltzmann model [A. Kupershtokh, D. Medvedev, and I. Gribanov, “Thermal lattice Boltzmann method for multiphase flows,” Phys. Rev. E 98, 023308 (2018)] is used for simulation. Different configurations of electric field were produced by using dissected flat electrodes of various shapes. On a simple flat electrode, droplets elongate after the application of electric voltage. Quite different behavior was observed when the central round part of the electrode was made non-conductive. In this case, the droplet spreads under the action of a non-uniform electric field, and the breakup and the formation of an annular structure were observed. A film of dielectric liquid flowing along a solid surface made of conductive and non-conductive transversal stripes exhibits a variety of regimes. When the voltage is low, the action of electric field produces waves at the surface of liquid. At a high voltage, the liquid is pinned to the edges of stripes, and the flow may be stopped completely. The purpose of this article is precisely to attract experimenters to the study of this type of phenomena.

Voltage‐Induced ON Switching of Magnetism in Ordered Arrays of Non‐Ferrimagnetic Nanoporous Iron Oxide Microdisks

AbstractTailoring the magnetic properties of ordered arrays of patterned structures usually requires stringent control of their size, pitch, microstructure, and composition. Here, a fundamentally different approach to manipulate the magnetic behavior of lithographed microdisks, based on the application of electrical voltage, is demonstrated. First, highly porous iron oxide films with virtually no magnetic response (OFF state) are grown by sol–gel chemistry. Subsequently, arrays of microdisks (8 µm in diameter) are obtained combining lithography with wet chemical etching processes. Electrolyte‐gating (with an anhydrous electrolyte) is then employed to induce a tunable (i.e., “on‐demand”) ferromagnetic response in these disks (OFF–ON switching of magnetism) at room temperature. The changes in magnetic properties are attributed to magnetoelectrically‐driven oxygen ion migration, which is enhanced due to nanoporosity. This causes partial reduction of the oxide phases to metallic Fe. The effect can be considerably reversed by applying voltage of opposite polarity. These results are appealing for diverse technological applications that require the use of patterned structures with easily tunable magnetic properties, such as magnetic micro‐electro‐mechanical systems, microfluidic, and lab‐on‐a‐chip platforms for biomedical therapies and, ultimately, energy‐efficient magnetic memories or neuromorphic computing.

Магнитоэлектрический эффект в гибридных системах сегнетоэлектрик/ферромагнитная пленка с анизотропией типа "легкая плоскость" и "легкая ось"

We studied the striction magnetoelectric effect in hybrid systems consisting of a magnetic film deposited on the ferroelectric surface. Films with planar (galfenol, nickel) and perpendicular (multilayer Co / Pt structures) magnetic anisotropy were used. PMN-PT crystal was used, as a ferroelectric. The hysteresis loops of magnetic films were investigated as a function of the voltage, applied to a ferroelectric crystal. In films with “easy plane” type anisotropy, a rotation of the axis directions in the plane of the sample was detected upon application of electric voltage. In structures with an "easy axis" type anisotropy, a change in the shape of the hysteresis loop is observed, which, according to the simulation, which can be associated with a change in the Dzyaloshinsky – Morii surface interaction at the Co and Pt interface

Electrically driven spin torque and dynamical Dzyaloshinskii-Moriya interaction in magnetic bilayer systems

Efficient control of magnetism with electric means is a central issue of current spintronics research, which opens an opportunity to design integrated spintronic devices. However, recent well-studied methods are mostly based on electric-current injection, and they are inevitably accompanied by considerable energy losses through Joule heating. Here we theoretically propose a way to exert spin torques into magnetic bilayer systems by application of electric voltages through taking advantage of the Rashba spin-orbit interaction. The torques resemble the well-known electric-current-induced torques, providing similar controllability of magnetism but without Joule-heating energy losses. The torques also turn out to work as an interfacial Dzyaloshinskii-Moriya interaction which enables us to activate and create noncollinear magnetism like skyrmions by electric-voltage application. Our proposal offers an efficient technique to manipulate magnetizations in spintronics devices without Joule-heating energy losses.

АКТИВНОЕ ГАШЕНИЕ ПОПЕРЕЧНЫХ КОЛЕБАНИЙ КОНСОЛЬНОЙ БАЛКИ ПЬЕЗОЭЛЕКТРИЧЕСКИМИ СЛОЯМИ С РАЗЛИЧНЫМИ ФОРМАМИ ЭЛЕКТРОДОВ

The damping efficiency is considered for a console beam described by a linear viscosity Bernoulli-Euler model. The article presents the methods of damping transverse vibrations implemented by a dynamic damper from a piezoelectric layer distributed symmetrically along the axis of symmetry of the beam. Piezoelectric layers with a triangular and rectangular shape of electrode plates are considered, which affects the nature of mechanical stresses upon application of electrical voltage. The electrode plates are thin layers made of nickel or silver several microns thick and located normal to the polarization axis, that is, along the length of the piezoceramic plate. The control of the piezoelectric layers is realized by changing the potential difference between the electrode plates, while the piezoelectric material uncoated by the electrode plate on both sides is useless to use as an active material. Mathematical models of the effect of piezoelectric elements on the cantilever beam are derived from the Hamilton principle. The Pareto-efficiency of quenching by piezoelectric plates with different electrode shapes is evaluated relative to two criteria: the level of control voltage and the maximum deflection of the beam. To compare the results with the best variant of vibration damping, in this formulation, the result of vibration damping for a beam with piezoelectric layer applied along the entire length is given. The damping efficiency was confirmed in an applied and particular example by means of vibrograms. The synthesis of Pareto-optimal controls is based on the Germeier convolution, and the search for optimal feedback is based on the application of the theory of linear matrix inequalities and effective algorithms for solving them.

Innovative and Energy Efficient Smart Window Based on Nanomaterial Technologies

Strategies for incorporating energy-efficiency requirements into building standards have been implemented by governments in developed countries in order to introduce the concept of green nanotechnology. Substituting regular glass windows in residential/commercial buildings with smart windows is the objective. This paper describes the development of innovative nanomaterial based membranes/coatings for smart windows that would work as electric dimming glass. Currently, curtains and blinds function to block sun light; eliminating such elements is of importance due to its limited functionality (e.g. blocking UV prevents sun light illumination), health (e.g. dust and germ collection especially in hospitals), disposal/recycling issues, cost, and maintenance. The proposed smart window is expected to block harmful UV light and provide a controlled privacy. Electrochromic smart windows are already in use and are able to vary their throughput of visible light and solar energy by application of electrical voltage and are able to provide energy efficiency and indoor comfort in buildings. These smart windows comprises of electrochromic materials such as LixWO2.89 and HxNiO2 as cathodic and anodic oxide films, respectively, and other complex polymers, which are complicated to create, expensive and some are hazardous in nature. Nanocellulose (achieved from wood/pulp product) is already being used in flexible electronics, so nanomaterial membrane for smart window is a probable alternative. This paper presents an innovative technology for smart-windows, utilizing nanocellulose fiber (abundantly available) doped with conductive nanoparticles (work as dimming glass on voltage application), mixed with minute amount of electrochromic material form thin film membranes.

Three-dimensional microfabrication using local electrophoresis deposition and a laser trapping technique.

We describe a novel fabrication method of three-dimensional (3D) microstructures using local electrophoresis deposition together with laser trapping. A liquid cell consisting of two-faced conductive substrates was filled with a colloidal solution of Au nanoparticles. The nanoparticles were trapped by a laser spot and positioned on the bottom substrate, then deposited onto the surface by the application of electrical voltage between the two substrates. By moving the liquid cell downward while maintaining the deposition, 3D microstructures were successfully fabricated. The smallest diameter of the fabricated pillar was 500 nm, almost the same as that of the Airy disc. The Young's modulus of the fabricated structure was 1.5 GPa.

Energy efficient reconcentration of diluted human urine using ion exchange membranes in bioelectrochemical systems

Nutrients can be recovered from source separated human urine; however, nutrient reconcentration (i.e., volume reduction of collected urine) requires energy-intensive treatment processes, making it practically difficult to utilize human urine. In this study, energy-efficient nutrient reconcentration was demonstrated using ion exchange membranes (IEMs) in a microbial electrolysis cell (MEC) where substrate oxidation at the MEC anode provides energy for the separation of nutrient ions (e.g., NH4+, HPO42−). The rate of nutrient separation was magnified with increasing number of IEM pairs and electric voltage application (Eap). Ammonia and phosphate were reconcentrated from diluted human urine by a factor of up to 4.5 and 3.0, respectively (Eap = 1.2 V; 3-IEM pairs). The concentrating factor increased with increasing degrees of volume reduction, but it remained stationary when the volume ratio between the diluate (urine solution that is diluted in the IEM stack) and concentrate (urine solution that is reconcentrated) was 6 or greater. The energy requirement normalized by the mass of nutrient reconcentrated was 6.48 MJ/kg-N (1.80 kWh/kg-N) and 117.6 MJ/kg-P (32.7 kWh/kg-P). In addition to nutrient separation, the examined MEC reactor with three IEM pairs showed 54% removal of COD (chemical oxygen demand) in 47-hr batch operation. The high sulfate concentration in human urine resulted in substantial growth of both of acetate-oxidizing and H2-oxidizing sulfate reducing bacteria, greatly diminishing the energy recovery and Coulombic efficiency. However, the high microbial activity of sulfate reducing bacteria hardly affected the rate of nutrient reconcentration. With the capability to reconcentrate nutrients at a minimal energy consumption and simultaneous COD removal, the examined bioelectrochemical treatment method with an IEM application has a potential for practical nutrient recovery and sustainable treatment of source-separated human urine.

Ferrite-piezoelectric light modulator with electric and magnetic control of magnetization

The influence of mechanical stresses developed in a piezoelectric lead zirconate titanate (PZT) plate on the domain structure of mechanically coupled epitaxial yttrium iron garnet (YIG) film has been studied. The application of electric voltage to the piezoelectric plate leads to magnetoelastic variations in the anisotropy of the garnet film, which is manifested by reorientation of the magnetization vector from the direction perpendicular to the film plane to a direction parallel to this plane. Using this effect, it is possible to perform magneto-optical modulation of light transmitted through the film. Estimations of the influence of film parameters on the orientation of magnetization and characteristics of light beam allow the optimum parameters of the composite structure for various modulation regimes to be determined.

Design, engineering and structural integrity of electro-responsive carbon nanotube- based hydrogels for pulsatile drug release.

Triggerable drug delivery from polymeric implants offers the possibility to generate remote-controlled drug release profiles that may overcome the deficiencies of conventional administration routes (intravenous injections and oral administration) including the toxicity due to overdose and systemic administration. An electro-responsive delivery system was engineered to deliver drug molecules in a pulsatile manner, controlled by the on/off application of electric voltage. Pristine multi-walled carbon nanotubes (pMWNTs) were incorporated into a polymethacrylic acid (PMAA)-based hydrogel matrix by in situ radical polymerisation. The effect of pMWNTs and cross-linker concentration on the electrical and mechanical properties of the hydrogel hybrids was thoroughly investigated. The incorporation of pMWNTs into the polymeric network improved the electrical properties of the hydrogel hybrids and drug release from the gels was significantly enhanced at high pMWNT concentrations, reaching 70% of the loaded dose after two short electrical stimulations. The presence of pMWNTs within the hydrogel matrix affected however the mechanical properties of the hydrogel by decreasing the pore size and therefore the swelling/de-swelling of the gels. The damage to the hybrid gel surfaces after electrical stimulation and the loss of the pulsatile release profile at high cross-linker concentrations suggested that the mechanism of drug release involved a compressing effect and intensified the stress on the polymeric network as a result of the electrical properties of pMWNTs.

Electrically controlled release of the nerve growth factor from a collagen-carbon nanotube composite for supporting neuronal growth.

We report the use of a nerve growth factor-loaded collagen-carbon nanotube (NGF-Col-CNT) composite as a substrate for in vitro growth of PC 12 cells. The feasibility of such novel composites as drug carriers was assessed using an in vitro drug-release test (ELISA immunoassay) in the presence of an electrical field. Subsequent studies included four-point probes, cyclic voltammograms, and in vitro PC 12 growth of fibers. The facile incorporation of NGF within fibrous collagen structures significantly mediated PC 12 (nerve) fiber process formation during the application of electrical voltage. Indeed, electrical stimulation (500 mV) using non-polarized Ag/AgCl electrodes to electro-active composites facilitated the sustained release of NGF. Given that PC 12 cells require NGF in the media to produce fiber outgrowth, this assay was clearly informative when the differentiation and branching of PC 12 cells into neurons was significantly enhanced. NGF responses were also evident from other developmental events including protrusions of neuronal filopodia and the formation of microspikes. Col-CNT composites, when electrically stimulated, could serve not only as neuronal scaffolds, but also as an electrically controllable drug release system to improve the performance and preferential timing of growth factor release in various biomedical applications.

Monitoring of fracture healing by electrical conduction: A new diagnostic procedure

Background:Electrical stimulation of fractures has been reported to enhance fracture healing. X-rays are normally used to assess union of fractures. Electrical conduction is not tried as a tool to study fracture healing. The current study focuses on electrical conduction as a diagnostic tool to assess fracture healing and new bone formation. The aim was to find if electrical resistance across the fracture can be used as a tool to study fracture healing which can be verified with simultaneous radiographs.Materials and Methods:A prospective study was conducted where 12 open fractures of tibia, including two with bone defects were evaluated. They were debrided and four-carbon ring Ilizarov external fixators were applied. Their healing was followed with clinical assessment and periodical X-rays till the endpoint of fracture union and then the rings were removed. In addition, all these cases also had application of electrical voltage in the range of 0.1–1.0 V DC in 0.1 V increments, across the two wires on either side of fracture. The output current was recorded by an ammeter connected in series. Resistance calculated for various voltages was plotted as a graph for the period of fracture treatment and the characteristics were studied. This graph was compared with the appearance of new bone in the X-rays.Results:In all cases, when the above graph stabilized, in the consecutive recordings, the X-rays showed healing (bridging callus) matching the curve and the patient was able to load the limb. The time of stabilization of this graph for a specific voltage was different in individual cases. However, for a given case, the resistance characteristics were the same for the entire voltage range of 0.1–1.0 V.Conclusion:If the resistance versus day curve stabilizes on the consecutive recordings, we can predict that the fracture is in the process of healing. This stabilization period also matched the patients’ ability to comfortably load the limb and also the radiographs which showed bridging callus (healing). If this is used as a positive criterion for fracture healing in future, the radiation exposure by X-rays shall be less.

Friction Control of a Gel by Electric Field in Ionic Surfactant Solution

We observed that the frictional force between acrylamide gel and silicon dioxide substrate is reduced upon application of electric voltage if the gel is swollen with anionic surfactant (sodium dodecyl sulfate). The effect was not seen in cationic surfactant. We conjecture that the reduction is due to formation of a lubrication layer by electric field at the gel/solid interface.

Generation and measurement of nonequilibrium spin currents in two-terminal systems

Generation and measurement of nonequilibrium spin current in two probe phase coherent conductors are discussed. It is argued and shown that spin current can be generated in a two-terminal nonmagnetic system by application of electrical voltage. These spin currents can be measured via conductance in two probe configuration when the detector probe is ferromagnetic. It is shown that for a two-terminal system with one ferromagnetic probe, the conductance depends on the absolute direction of magnetization and is related to spin currents. Thus, this allows one to measure spin currents via conductance.

E34 電圧印加による難削材の超精密切削加工(OS-11 超精密加工(2))

An electrical method for suppression of tool wear and improvement of finished surface texture was proposed in ultraprecision diamond turning of hard-to-cut materials. In face turning of carbon steel (SS400) with polycrystalline CVD diamond tool, electric voltage (10V) was applied between tool and workpiece. By this method the flank wear of the tool was reduced comparing to the case of normal (non-voltage) turning. As for the finished surface, craters formed by tearing action during cutting were remarkably reduced by the application of electric voltage, and the surface roughness became smaller. The improvement of finished surface texture by the application of electric voltage was also possible in face turning of carbon steel (SS400) with monocrystalline diamond tool.

Reversible strain effect in La0.7Sr0.3MnO3 step edge junctions

The spin-polarized electric transport in ferromagnetic La0.7Sr0.3MnO3 films on piezoelectric substrates with etched steps has been investigated. The Pb(Mg1∕3Nb2∕3)0.72Ti0.28O3 substrate is strained reversibly by application of electric voltage. This includes strain control in film junctions formed at step edges. The film resistance (R) is very sensitive to both strain and magnetic field in a wide temperature range, 30K<T<300K, in contrast to the behavior of step-free films. Both R and magnetoresistance decrease (increase) significantly upon in-plane compression (expansion). In this way, strain is introduced as variable parameter for experiments on step edge grain boundaries.

Reversible Wetting−Dewetting Transitions on Electrically Tunable Superhydrophobic Nanostructured Surfaces

In this work, electrically controlled fully reversible wetting-dewetting transitions on superhydrophobic nanostructured surfaces have been demonstrated. Droplet behavior can be reversibly switched between the superhydrophobic Cassie-Baxter state and the hydrophilic Wenzel state by the application of electrical voltage and current. The nature of the reversibility mechanism was studied both experimentally and theoretically. The reported results can provide a new method of dynamically controlling liquid-solid interactions.

Electrically tunable superhydrophobic nanostructured surfaces

In this work, we discuss dynamic electrical control of the wetting behavior of liquids on nanostructured surfaces spanning the entire possible range from superhydrophobic behavior to nearly complete wetting. It is demonstrated that a droplet of liquid can be reversibly switched between the superhydrophobic “rolling ball” state and the hydrophilic immobile droplet state by the application of electrical voltage and current. The nature of the transition mechanism is studied both experimentally and theoretically. The reported results provide novel methods of manipulating liquids at microscale.