Application Of External Electric Field Research Articles

Influences of electric fields on the operation of Aqy1 aquaporin channels: a molecular dynamics study.

The dynamics of water molecules inside an Aquaporin channel, embedded within a stochastically fluctuating membrane, was modeled by means of the application of the molecular dynamics (MD) simulation method. We considered the effect of the existence and nonexistence of an external electric field, either constant or oscillating, on the stability of the channel. It was observed that the permeation of water molecules through the channel was increased when the channel was exposed to a constant electric field of strength -0.2 mV nm-1. Moreover, oscillating electric fields of 5 and 10 GHz frequencies, which is the range of field frequency generally present in our daily life, were applied to the channel, showing not significant effects on the stability of the channel and its important parts. In addition, we investigated the influence of the application of electric fields on the water molecule ordinations in the channels, and the results showed that the water molecule orientations were changed in response to the applied field.

Recent advances with electro-optic polymers

In recent years the electro-optic polymers emerged as an important branch of material science. This growth and interest is fundamentally motivated by practical application of these materials in second-order nonlinear optics and in waveguiding configuration. Indeed, these materials marry excellent optical quality of amorphous σ bonded polymers with enhanced first hyperpolarizability of imbedded organic nonlinear optical molecules. Although a big progress was achieved with them, concerning particularly the science, understanding and applications, some problems remain still incompletely solved, particularly the stability of induced polar order by the application of external electric field and the molecule aggregation. In this review paper we recall techniques of thin film fabrication, poling, characterization of NLO properties and discuss more precisely problems of molecule aggregation as well as the temporal decay of polar order. A novel 3D second-order NLO chromophores, namely the [2] paracyclophanes, which may help to limit the aggregation, are proposed. We show, in particular, that this molecule can be poled in doped PMMA thin films. Practical applications of electro-optic polymers are also reviewed and discussed.

Band Gap Modulation by Two-Dimensional h-BN Nanostructure

Two-dimensional hexagonal boron nitride (h-BN) as a graphene-like material was investigated due to its impending applications in electronics. The h-BN band gap Eg as an important factor and its variation between bilayer ZrSe2 sheets were explored under an external electric field. The initially indirect band gap is found to convert to direct band gap by means of density functional theory. Additionally, the band gap is modulated by van der Waals corrections from 0.21220 to 0.01770 eV. Based on the results, the proposed heterostructure is converted to the direct band gap, and band gap smoothly decreased from 0.25440 to 0.0436 eV following the application of external electric field from 0.2 to 0.6 eV. Moreover, ZrSe2|h-BN|ZrSe2 is investigated under the applied biaxial compressive strain from 1 to 4%. The findings demonstrated that the gap was decreased by any compressive strain amplification, while the semiconducting behavior in the heterostructure attained to the semi-metallic performance under the increasing strain.

Assessment of dynamical properties of mercaptopurine on the peptide-based metal-organic framework in response to experience of external electrical fields: a molecular dynamics simulation.

In this work, the effect of the external electric field (EF) on the drug delivery performance of peptide-based metal-organic framework (MPF) for 6-mercaptopurine (6-MP) drug is investigated by means of the molecular dynamics (MD) simulations. It is found that the strength interaction of drug molecule with MPF is decreased under the influence of the electric field. In other words, the adsorbed drug molecules have more tendencies for the interaction with the porous nanostructure in the absence of EF. According to the radial distribution function (RDF) patterns, the probability of finding drug molecules in terms of the intermolecular distance with respect to the MPF surface is lowest during the high field strength. As the EF strength increases, the spread of drug molecules around MPF results in high dynamics movement and further more diffusion coefficient of drug molecule in the simulation system. This result emphasizes the weak intermolecular interaction of drug molecules with MPF with the application of EF. Assessment of dynamical properties of 6-mercaptopurine in the presence of EF with various strengths reveals that the applied electric field can act as a trigger on liberation behavior of drug from the porous nanostructure.

Thermoelectric properties of gapped bilayer graphene

Unlike in conventional semiconductors, both the chemical potential and the band gap in bilayer graphene (BLG) can be tuned via application of external electric field. Among numerous device implications, this property also designates BLG as a candidate for high-performance thermoelectric material. In this theoretical study we have calculated the Seebeck coefficients for abrupt interface separating weakly- and heavily-doped areas in BLG, and for a more realistic rectangular sample of mesoscopic size, contacted by two electrodes. For a given band gap () and temperature (T) the maximal Seebeck coefficient is close to the Goldsmid–Sharp value , the deviations can be approximated by the asymptotic expression , with the electron charge −e, the Boltzmann constant , and . Surprisingly, the effects of trigonal warping term in the BLG low-energy Hamiltonian are clearly visible at few-Kelvin temperatures, for all accessible values of meV. We also show that thermoelectric figure of merit is noticeably enhanced (ZT > 3) when a rigid substrate suppresses out-of-plane vibrations, reducing the contribution from ZA phonons to the thermal conductivity.

Investigation of giant dielectric and room temperature ferromagnetic response of facile CZTO nanostructure

Cubic CoZnTiO4 (CZTO) nanocomposite structure has been synthesized via a modest chemical method at a much lower calcination temperature. The possible phase formations and crystalline nature of the as synthesized structure has been studied by X-ray diffraction technique. FESEM micrographs depict the grain growth within the nanocomposite. Thermal analysis shows endothermic as well as exothermic peaks which points out the thermal stability over the observed temperature range. The synthesized CZTO nanocomposite structure shows nearly frequency independent giant dielectric response on application of external electric field. The nanostructure shows e′ ~ 21,000 at 40 Hz frequency. With the help of internal barrier layer capacitor model, the origin of this large dielectric constant is well explained. The impedance spectroscopy analysis and equivalent circuit response also supports the obtained result. On application of external magnetic field, the synthesized CZTO sample also shows room temperature ferromagnetic response. This magneto-dielectric response of CZTO nanostructure enables it to be a superior material for forthcoming device application.

Dual‐Action Flexible Antimicrobial Material: Switchable Self‐Cleaning, Antifouling, and Smart Drug Release

AbstractA switchable material with a smart antimicrobial dual‐action functionality, which is based on a highly stretchable silicon polymer gradiently doped with polyyrrole, is proposed. The material exhibits superhydrophobic and self‐cleaning properties, high aerophilicity as well as the possibility of smart, electrically triggerable release of an incorporated drug. During the immersion of the material in water, an air gap is formed on its surface which prevents a formation of biofouling, attachment of microorganisms, and burst release of the incorporated drug. An application of external electric field switches the surface properties from the superhydrophobic to highly hydrophilic state that enables a wetting of the material surface and electrically triggered release of a loaded drug. After the electric field switching off and sample drying, the material surface returns to its intrinsic superhydrophobic state with the original self‐cleaning properties so that the material surface can be simply cleaned, removing the bacteria. High flexibility and stretchability are additional favorable properties of the proposed smart antimicrobial material, making it a suitable candidate for a range of medical and related applications.

Stationary and Dynamical Properties of Polarons in Anisotropic C60-Crystals

Two-dimensional C60 crystals are treated with a Holstein–Peierls model that takes into account both intra- and intermolecular vibrational modes to describe charge transport. By virtue of this procedure, we obtained the set of values for intra- and intermolecular electron–phonon coupling that makes it possible to study stationary properties of polarons as well as to investigate the transport regime of the charge carriers. This is carried out by considering the presence of anisotropy of electronic terms and effects because of the application of external electric fields. We have mapped the regimes in which polarons of different nature—each endowing the system with different properties—are observed.

Disease antigens detection by silicon nanowires with the efficiency optimization of their antibodies on a chip

Enhancing the efficiency of antibody protein immobilized on a silicon nanowire-based chip for their antigens detection is reported. An external electric field (EEF) is applied to direct the orientation of antibodies during their immobilization on a chip. Atomic force microscopy (AFM) is used to measure the binding forces between immobilized antibody and targeting antigen under the influence of EEF at different angles. The maximum binding force under a specific angle (optimal angle; oa) of EEF (maxEEFoa) implies the optimal orientation of the antibodies on the chip. In this report, two different cancer carcinoembryonic antigen (CEA)-related cell adhesion molecules 5 (CEACAM5) & 1 (CEACAM1) were used for the examples of disease antigen detection. maxEEFoa of anti-CEACAM5 or anti-CEACAM1 immobilized on a general chip was firstly determined. Spectroscopy of AFM revealed that both binding forces were the largest ones with their antigens when maxEEFoa was applied as compared with no or other angles of EEF. These antibody proteins accompanied with the application of EEF were secondly immobilized on silicon-nanowires (n = 1000) and the field effects were measured (∆I) as their target antigens were approached. Results showed that ∆I was the largest ones when maxEEFoas (225°/270° and 135°/180° for anti-CEACAM5 and anti-CEACAM1, respectively) were applied as compared with other angles of EEF. These observations imply that the silicon nanowires together with the application of maxEEFoa as detection tools could be applied for the cancer diagnostics in the future.

Elemental Behaviors of Molten FeO-SiO2-Fe3O4-Based Copper Slags

The various elemental behaviors of copper, lead and zinc in molten copper slags under an external electrical field at 1503 K are described. The molten copper slag cleaning process can be significantly improved by a vertical electric field. Compared to the natural settling process, the copper recovery rate increased from 20% to 92%. An external electric field in the slag cleaning process can accelerate the copper enrichment in the cathode and decrease its oxygen element content. In addition, the application of external electric fields can also be propitious for the removal of some heavy metal elements including zinc and lead.

Investigation of external electrode shape for resist film thickness control by application of external electric field in electrostatic spray coating processes

Investigation of external electrode shape for resist film thickness control by application of external electric field in electrostatic spray coating processes

Acid Hydrolysis of Regular Corn Starch under External Electric Field

The main objective of the present work is the investigation of a new method for starch hydrolysis. For this, we proposed the acid hydrolysis under the action of an external electric field, able to develop a faster reaction than the conventional one. Corn starch with 18% amylose was subjected to a fixed voltage, varying the external electric field application time and the number of cycles. Morphology, crystallinity, and thermal stability of the starches were investigated by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and small-angle X-ray scattering (SAXS). The results showed that the acid hydrolysis coupled with an external electric field allows a significant reduction in hydrolysis time, due to the orientation of the electrolyte ions. Cavities were observed at the surface of hydrolyzed starches after treatment. However, the principal feature is related to the increase of the granule crystallinity with increasing hydrolysis time. The results suggest that the starches treated by this new method are interesting candidates for application in the food industry if greater gelatinization resistance is required.

Band gap modulation of ZrX2 (X = S, Se, Te) mono-layers under biaxial strain and transverse electric field and its lattice dynamic properties: a first principles study

The effect of strain on the electronic properties of mono-layers of Zirconium based dichalcoge nides ZrX2 (X = S, Se, Te) was studied using density functional theory based first-principles calculations. The variation in band gap due to biaxial tensile as well as compressive strain was calculated in these mono-layers. The modulation in band gap on application of external electric field has also been studied and it is observed that it decreases monotonically on applying a transverse electric field. These mono-layers and their strained structure are found to be dynamically stable as observed from their phonon spectrum. The population analysis in these systems indicates that with decreasing strain the d-population of Zr atoms increases whereas the p-population of S, Se, Te atoms decreases.

Resistivity switching in activated carbon fibers

This work presents the effect of switching of resistivity of activated carbon fibers, obtained with a combination of adsorption of specific molecules and application of external electric field. Observed resistivity jumps were due to the ordering of dipolar guest molecules which acted as a gating factor for transport of charge carriers within the granular structure of the fiber. Presented research shows that the control of electrical transport in porous carbon systems is possible by means of structure, host-guest interactions and temperature, combined with external stimulation. As such it is important for fundamental understanding of electronic properties of graphene-based systems, and for their adsorption-related applications, for example energy generation and storage. Resistivity switching might prove useful for tuning of carrier transport in nanoelectronic units (single-electron transistors, spin valves) or for enhancing the performance of molecular sensors.

In-situ X-ray diffraction on functional thin films using a laboratory source during electrical biasing

A methodology that allows the quantification of structural changes in functional thin films during the application of external electrical field is reported. The originality of this method is the development of a set-up using a laboratory X-ray source since most of previous Operando studies have used synchrotron radiations. Several technical challenges have been addressed: the (i) optimization of the electrical contact and the sample geometry within the lab-source goniometers, (ii) evaluation of any X-ray dose effect on the Metal/Insulator/Metal structure to prevent eventual charge accumulation at the electrode interfaces and (iii) the quantification of the effect of the time-delay, needed for X-ray measurement, on domain switching. The validity of our method has been demonstrated on a prototypic sol-gel lead zirconate titanate (PZT) thin film where the polarization and structural changes have been simultaneously measured. The evolution of ferroelastic domains as a function of external electric field has been quantified and two different effects have been successfully separated: (a) the cell extension and (b) domain wall motion described as the switching between a and c tetragonal domains.

Multiferroic and magnetoelectric studies on BMFO–NZFO nanocomposites

Bismuth ferrite-based multiferroic composites, x⋅Bi0.95Mn0.05FeO3 − (1 − x)⋅Ni0.5Zn0.5Fe2O4, where x takes the values of 0.2, 0.4, 0.5, 0.6 and 0.8, have been prepared by combining sol–gel autocombustion and solid-state methods. Phase identification of the samples was done by X-ray diffraction analysis. SEM–EDX measurements on the samples were used to evaluate the microstructural aspects and quantitative evaluation of the samples. Room temperature P–E loop measurements on the samples were done under the application of external electric fields in the range from 0 to 6 kV/mm at a frequency of 50 Hz to understand the ferroelectric strength of the compounds. Magnetic studies on the samples were made by M–H loop measurements in the field range of ± 10 kOe. Magnetoelectric coupling measurements were made using a dynamic lock-in test set-up. The results indicate that the mixing of nickel–zinc ferrite in Bi0.95Mn0.05FeO3, in spite of the enhanced conductivity, has produced considerable improvements in saturation magnetization while retaining the remnant ferroelectric polarization in reasonable magnitudes to obtain improved M–E coupling. Among all the composites, the composite with x = 0.5 has resulted better M–E performance.

Periodic electrolysis technique for in situ fouling control and removal with low-pressure membrane filtration

Electrically conductive membranes and their application for desalination pre-treatment and water purification have an exceptional performance due to self-cleaning of fouling deposits by the application of external electric fields. However, the effectiveness of existing conductive membranes is hampered by their common applications. The current approach aims to better understand the in situ fouling mitigation and enhanced flux by employing two different electrically conductive coated feed spacer configurations during filtration of humic acid at concentrations of 8, 12, 16 and 20 ppm. Periodic electrolysis was applied for a duration of 2 min with three intervals of 30, 45 and 60 min. A comparison of both the feed spacers was made in terms of the effect of the applied potential and interval time on enhancement of water flux, as well as the required energy consumption at four different concentrations. In terms of enhanced flux and energy consumption, feed spacer A (2 × 2 mm aperture size) revealed better results than feed spacer B (3 × 2 mm), which may be attributed to a greater conductive area. The reported technique shows a major advantage of in situ feed spacer self-cleaning, thus providing a continuous and non-destructive approach for the mitigation of surface fouling.

Experimental Tests and Aeroacoustic Simulations of the Control of Cavity Tone by Plasma Actuators

A plasma actuator comprising a dielectric layer sandwiched between upper and lower electrodes can induce a flow from the upper to lower electrode by means of an externally-applied electric field. Our objective is to clarify the mechanism by which such actuators can control the cavity tone. Plasma actuators, with the electrodes elongated in the streamwise direction and aligned in the spanwise direction, were placed in the incoming boundary of a deep cavity with a depth-to-length ratio of 2.5. By using this experimental arrangement, the amount of sound reduction (“control effect”) produced by actuators of differing dimensions was measured. Direct aeroacoustic simulations were performed for controlling the cavity tone by using these actuators, where the distributions of the body forces applied by the actuators were determined from measurements of the plasma luminescence. The predicted control effects on the flow and sound fields were found to agree well with the experimental results. The simulations show that longitudinal streamwise vortices are introduced in the incoming boundary by the actuators, and the vortices form rib structures in the cavity flow. These vortices distort and weaken the two-dimensional vortices responsible for producing the cavity tone, causing the tonal sound to be reduced.

Ferroelectric-Paraelectric Transition In A Membrane With Quenched-Induced \u03b4-Phase Of PVDF

The stabilization of δ-phase of poly(vinylidene fluoride) PVDF in a 14 µm-thickness ferroelectric membrane is achieved by a simple route based on the use of a dimethylformamide (DMF)/acetone solvent, in which the application of external electric field is not required. X-ray diffraction and calorimetric experiments on heating reveal that, at 154 °C, the original mixture between ferroelectric δ-phase and paraelectric α-phase transits to a system with only this latter phase in the crystalline fraction. A gradual and slight increment of amorphous fraction up to the melting at 161 °C is also observed. The existence of δ-phase is corroborated by the occurrence of a broad maximum around 154 °C in dielectric permittivity measurements, as well as the hysteresis loops observed at room temperature. These results suggest a wide thermal window for a stable δ-phase, between room temperature and 154 °C, a subsequent transition into α-phase and the corresponding melting at 161 °C. The broad dielectric maximum observed around 154 °C in dielectric and calorimetric measurements, can be associated with a diffuse ferroelectric-paraelectric transition.

Analysis of a Li-Ion Nanobattery with Graphite Anode Using Molecular Dynamics Simulations

Molecular dynamics simulations were performed to investigate the initial charging of a Li-ion nanobattery with a graphite anode and lithium hexaflourphosphate (LiPF6) salt dissolved in ethylene carbonate (CO3C2H4) solvent as the electrolyte solution. The charging was achieved through the application of external electric fields simulating voltage sources. A variety of force fields were combined to simulate the materials of the nanobattery, including the solid electrolyte interphase, metal collectors, and insulator cover. Some of the force field parameters were estimated using ab initio methods, and others were taken from the literature. We studied the behavior of Li-ions traveling from cathode to anode through electrolyte solutions of concentrations 1.15 and 3.36 M. Time-dependent variables such as energy, temperature, volume, polarization, and mean square displacement are reported; a few of these variables, as well as others such as current, resistance, current density, conductivity, and resistivity are r...