Electric Field In Water Research Articles

External electric field effects on asphaltene adsorption on Kaolinite-water interface: A molecular dynamics study

Applying electric fields to promote water/oil recovery efficiency is gaining increasing attention in downstream of heavy oil development. In this work, molecular dynamics simulations were performed to study the motion of N-(1-Hexylheptyl)-N′-(5-carboxylicpentyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe) between kaolinite (Kaol) surfaces mediated by external electric field in water under different pH. Aggregation of C5Pe was mainly mediated by pH and not affected by the electric field, while adsorption responded to both pH and the electric field. In neutral and alkaline solutions, C5Pe was deprotonated, and its distribution between two Kaol surfaces was mainly mediated by the Coulombic force exerted by the electric field. In acidic solutions, C5Pe carried zero charge, and yet its distribution was still affected by the electric field. The external electric fields mediated the wettability of the two Kaol surfaces in different extents, and C5Pe preferred to adsorb on the more hydrated surface. The mediation of the electric fields on the wettability of surfaces was achieved in two stages. In the first stage, when the electric field of a low strength was applied, diffusion of water enhanced. The hydration of both Kaol surfaces became increased as water molecules formed more hydrogen bonds with the surfaces. As the electric field strength became sufficiently high, diffusion showed no further enhancement, and the re-orientation of water dipoles started dominating the hydrogen bonding with the surfaces. Carrying opposite charges, the hydrogen bond donors and acceptors of water were differently regulated by the electric field, and therefore water molecules conformed in a certain manner under the electric field of high strength. As a result, the hydrogen bonding between water and the two Kaol surfaces (placed on two sides of the simulated box under the electric field) varied with their positions. Due to the structural hindrance of the hydroxyl groups on the surface, the surface could provide more hydrogen bonding donors formed more hydrogen bonds with water, and thus became more hydrophilic and had stronger attraction to C5Pe.

Determination of Highly Transient Electric Field in Water Using the Kerr Effect with Picosecond Resolution

This study utilizes the Kerr effect in the analysis of a pulsed electric field (intensity ~108 V/m, limited by the liquid dielectric strength) in deionized water at the sub-nanosecond time scale. The results provide information about voltage waveforms at the field-producing anode (160 kV peak, du/dt > 70 kV/ns). The analysis is based on detecting the phase shifts between measured and reference pulsed laser beams (pulse width, 35 ps; wavelength, 532 nm) using a Mach–Zehnder interferometer. The signal-to-noise ratio of the detected phase shift is maximized by an appropriate geometry of the field-producing anode, which creates a correctly oriented strong electric field along the interaction path and simultaneously does not electrically load the feeding transmission line. The described method has a spatial resolution of ~1 μm, and its time resolution is determined by the laser pulse duration.

Eradication of Enterobaracter aerogenes, Escherichia coli, Listeria monocytogene, Staphylococcus aurous, and Acetobacter by High Voltage Pulsed Electric Field in Water and Milk Samples

ABSTRACT: Ensuring food and water safety has always been a health challenge globally. The present papers underscores HV-PEF (High Voltage Pulsed Electric Field), a novel approach to eliminate five kinds of microbes prevalent in milk and water in fractions of a second. These microorganisms are Enterobaracter aerogenes, Escherichia coli, Listeria monocytogene, Staphylococcus aurous, and Acetobacter. Objective was to find out the impact of HV-PEF on survival of selected species of bacteria, which are often considered as a concern for water and milk safety. A laboratory experimental setup was designed for producing HV-PEF, which was applied on sample of water and milk. The water sample was obtained from tap, and the milk sample was obtained from Bubalus bubalis. The microbial count was measured by plate method for both samples pre and post exposure to the HV-PEF. The effect was measured with combinations of varying field intensity and number of pulses, the intensity of the field having the highest value of 180 kV/cm (kilovolt-per-centimeter), and the pulse count varied between one to one hundred. Results showed, the endurance of few species was extremely low, at 40 kV filed intensity and 40 pulses. Other microbes also demonstrated low survival ratio (SR) at more than 40kV with pulses-count above 40. Complete inactivation of E. coli was achieved at around 80kV. The inactivation of microbe by HV-PEF varies with morphology and shape of the microorganisms. The annihilation of microorganisms is due to the rupturing of cell wall of microbe by the effect of HV-PEF, instead of ohmic heating (resistance induced).

Electric-field-coupled oscillators for collective electrochemical perception in biohybrid robotics

This work explores the application of nonlinear oscillators coupled by an electric field in water, inspired by weakly electric fish. Such coupled oscillators operate in clear and colloidal (mud, bottom silt) water and represent a collective electrochemical sensor that is sensitive to global environmental parameters, the geometry of the common electric field and spatial dynamics of autonomous underwater vehicles (AUVs). Implemented in hardware and software, this approach can be used to create global awareness in a group of robots, which possess limited sensing and communication capabilities. Using oscillators from different AUVs enables extension of the range limitations related to the electric dipole of a single AUV. Applications of this technique are demonstrated for detecting the number of AUVs, distances between them, perception of dielectric objects and synchronization of behavior. Recognizing self-/nonself-generated signals by electric fish is re-embodied in a technological way through an ‘electrical mirror’ for discrimination between ‘collective self’ and ‘collective nonself’. These approaches have been implemented in several research projects with bioinspired/biohybrid systems in fresh and salt water, and electrochemical sensing in fluidic media.

Simulation of Electrooptical Measurements of Prebreakdown Electric Fields in Water—Part I: Electric Field Near Anode Streamer

The analysis of the results of electrooptical measurements using the Kerr effect at the prebreakdown stage of an electric discharge in water made it possible to estimate the intensity of the inception field of the anode streamer. The electric field strength and phase difference distribution were constructed using computer simulation in the point-to-plane system near the anode tip. The conditions of an actual experiment are simulated. It turned out that taking into account the nonlinearity of the relative permittivity and saturation of polarization leads to a sharp increase in the field strength in a narrow region near the needle tip and compression of both the strong field region and compression of Kerr fringes. Taking these factors into account made it possible to explain the unusual shape of the chronogram and to estimate the field strength of the appearance of the anode streamer as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> ~ 40–50 MV/cm.

Nuclear Quantum Effects Largely Influence Molecular Dissociation and Proton Transfer in Liquid Water under an Electric Field.

Proton transfer in liquid water controls acid-base chemistry, crucial enzyme reactions, and the functioning of fuel cells. Externally applied static electric fields in water are capable of dissociating molecules and transferring protons across the H-bond network. However, the impact of nuclear quantum effects (NQEs) on these fundamental field-induced phenomena has not yet been reported. By comparing state-of-the-art ab initio molecular dynamics (AIMD) and path integral AIMD simulations of water under electric fields, I show that quantum delocalization of the proton lowers the molecular ionization threshold to approximately one-third. Moreover, also the water behavior as a protonic semiconductor is considerably modified by the inclusion of NQEs. In fact, when the quantum nature of the nuclei is taken into account, the proton conductivity is ∼50% larger. This work proves that NQEs sizably affect the protolysis phenomenon and proton transfer in room-temperature liquid water.

Synthesis of Copper and Copper Oxide Nanomaterials by Pulsed Electric Field in Water with Various Electrical Conductivities.

Nanomaterial synthesis is a hot research subject that has been extensively studied in the last two decades. Recently, plasmas in liquid systems have been proposed as an efficient means of synthesizing various types of nanomaterials. The formation processes implicate many physical and chemical phenomena that take place at the electrode surface, as well as in the plasma volume, which renders it difficult to fully understand the underlying mechanisms. In this study, we assess the effect of electric field on nanomaterial synthesis in a system composed of two copper electrodes immersed in water, in the absence of an electrical discharge. The obtained results indicate that various nanostructures, including copper nanoparticles, copper oxide nanowires, and/or hollow nanoparticles, may be produced, depending on the electrical conductivity of the solution (adjusted by adding highly diluted HCl to deionized water). The materials synthesized herein are collected and characterized, and a formation mechanism is proposed. Overall, our results provide insight into the physical and chemical phenomena underlying nanomaterial synthesis in plasmas in liquid.

Polyelectrolyte in Electric Field: Disparate Conformational Behavior along an Aminopolysaccharide Chain.

Electrical signals are increasingly used in fabrication of hydrogels (e.g., based on aminopolysaccharide chitosan) to guide the emergence of complex and anisotropic structure; however, how an imposed electric field affects the polymer chain conformation and orientation during the self-assembly process is not understood. Here, we applied nonequilibrium all-atom molecular dynamics simulations to explore the response of a charged chitosan chain comprising 5- or 20-monomer units to a constant uniform electric field in water and salt solution. While no conformational or orientational response was observed for the polyelectrolyte (PE) chains under the small electric fields within the simulation time, a field strength of 400 mV/nm induced significant changes. In water, a 5-mer chain is found to be slightly bent and oriented parallel to the field; however, surprisingly, a 20-mer chain displays candy-cane-like conformations whereby one half of the chain is collapsed and flexible, while the other half of the chain is stretched along the electric field. In salt solution, the disparity remains between the two halves of the 20-mer chain, although the backbone is extremely flexible with multiple bent regions and non-native conformations occur near the chain center in one of the three trajectories. The disparate conformational response along the polyelectrolyte chain may be attributed to the balancing forces between chain dynamics, electric polarization, counterion binding, and hydrodynamic pressure as well as friction. These findings reconcile existing experiments and theoretical studies and represent an important step toward understanding the complex roles of electric field and salt in controlling the structure and properties of soft matter.

Artificial carbon cilium using induced charge electro-osmosis

Artificial cilia are promising as a next generation microfluidic device. In this study, we experimentally report that fibrous carbon wires produced by the self-organization process show cilium motions due to induced charge electro-osmosis (ICEO) under AC electric fields in water. In particular, we experimentally demonstrate that the carbon ICEO cilium with a branching wire structure shows asymmetric beating motion. We believe that our findings will contribute to the research of artificial cilia having asymmetrical motions, which would provide net propulsion in a low Reynolds number regime.

A comprehensive guide to set up correctly an electrofishing gear.

This study aimed to describe the influence of different electrofishing engine configurations on electric field dispersion in water. Several experiments with original results are included. The aims were to (i) assess the equivalent electrode resistances and the output voltage at the anode, (ii) assess the influence of electrode misuse on the dispersal of the electric field in water, (iii) assess the influence of the duty cycle and the frequency on the radius of attraction around the anode, and (iv) set the voltage and the duty cycle based on information from models for backpack and bankside electrofishing engines. A synthesis of equivalent electrode resistances from different studies was created. Using an oxidised anode induced a decrease in the radius of attraction. Frequency had no influence on the radius of attraction, in contrast to the duty cycle. Models including the voltage and the duty cycle were created to enable the configuration of electrofishing engines.

Screening of an Electric Field in Water

The screening of an electric field in water has been studied taking into account correlations between protons, which are described by the ice rules. It is shown that the problem has two characteristic screening lengths l1 ≪ l2, which are determined by majority and minority charge carriers in water. The commonly accepted static dielectric constant of water about 83 at room temperature is applicable only in the distance range l1 ≪ x ≪ l2. At smaller distances, the dielectric constant is determined by the high-frequency dielectric constant and is ϵ∞ ≈ 3.2, whereas the dielectric constant at large distances tends to infinity, which corresponds to the complete screening of the electric field. The screening lengths have been numerically determined, their temperature dependences have been described, and an experiment has been proposed to test the results obtained.

Non-equilibrium simulations of thermally induced electric fields in water.

Using non-equilibrium molecular dynamics simulations, it has been recently demonstrated that water molecules align in response to an imposed temperature gradient, resulting in an effective electric field. Here, we investigate how thermally induced fields depend on the underlying treatment of long-ranged interactions. For the short-ranged Wolf method and Ewald summation, we find the peak strength of the field to range between 2 × 10(7) and 5 × 10(7) V/m for a temperature gradient of 5.2 K/Å. Our value for the Wolf method is therefore an order of magnitude lower than the literature value [J. A. Armstrong and F. Bresme, J. Chem. Phys. 139, 014504 (2013); J. Armstrong et al., J. Chem. Phys. 143, 036101 (2015)]. We show that this discrepancy can be traced back to the use of an incorrect kernel in the calculation of the electrostatic field. More seriously, we find that the Wolf method fails to predict correct molecular orientations, resulting in dipole densities with opposite sign to those computed using Ewald summation. By considering two different multipole expansions, we show that, for inhomogeneous polarisations, the quadrupole contribution can be significant and even outweigh the dipole contribution to the field. Finally, we propose a more accurate way of calculating the electrostatic potential and the field. In particular, we show that averaging the microscopic field analytically to obtain the macroscopic Maxwell field reduces the error bars by up to an order of magnitude. As a consequence, the simulation times required to reach a given statistical accuracy decrease by up to two orders of magnitude.

Microscopic mechanism of thermomolecular orientation and polarization.

Recent molecular dynamics simulations show that thermal gradients can induce electric fields in water that are comparable in magnitude to electric fields seen in ionic thin films and biomembranes. This surprising non-equilibrium phenomenon of thermomolecular orientation is also observed more generally in simulations of polar and non-polar size-asymmetric dumbbell fluids. However, a microscopic theory linking thermomolecular orientation and polarization to molecular properties is yet unknown. Here, we formulate an analytically solvable microscopic model of size-asymmetric dumbbell molecules in a temperature gradient using a mean-field, local equilibrium approach. Our theory reveals the relationship between the extent of thermomolecular orientation and polarization, and molecular volume, size anisotropy and dipole moment. Predictions of the theory agree quantitatively with molecular dynamics simulations. Crucially, our framework shows how thermomolecular orientation can be controlled and maximized by tuning microscopic molecular properties.

The effects of a lanthanide metal alloy on shark catch rates

Bycatch of sharks in longline fisheries has contributed to declines in shark populations and prompted the need for exploring novel technologies to reduce the incidental capture of sharks. One potential strategy is to exploit the unique electrosensory system of sharks, used to detect weak electric fields. Metals from the lanthanide series, made up of neodymium (Nd) and praseodymium (Pr), produce strong electric fields in water. In this study, we tested the effects of an Nd/Pr alloy on shark catch rates. Using longline fishing gear, we compared the catch rates of baited hooks affixed with either a block of the metal alloy (experimental) or a lead weight (control). Four experiments were conducted in different regions of the Pacific Ocean. Two bottom longline experiments were conducted inside and offshore of Kaneohe Bay, Hawaii. One of these experiments targeted young of the year scalloped hammerhead sharks (Sphyrna lewini), while the other targeted sandbar (Carcharhinus plumbeus) and tiger sharks (Galeocerdo cuvier). In the Southern California Bight (SCB), pelagic longlines were deployed to target mako (Isurus oxyrinchus) and blue sharks (Prionace glauca) and longlines targeting pelagic sharks were set in the Eastern Tropical Pacific (ETP) off Ecuador. There was a significant reduction in juvenile hammerhead sharks caught on hooks with the lanthanide metal compared to the controls. In contrast, there was no difference in the catch rates for experiments targeting sandbar sharks in Hawaii or those conducted in the SCB and Ecuador. These results suggest that there are inter-specific differences regarding the effects of lanthanide metals on catch rates. This may reflect the diverse feeding strategies and sensory modalities used by shark species for detecting and attacking prey.

Nuclear spin optical rotation and Faraday effect in gaseous and liquid water

Nuclear spin optical rotation (NSOR) of linearly polarized light, due to the nuclear spins through the Faraday effect, provides a novel probe of molecular structure and could pave the way to optical detection of nuclear magnetization. We determine computationally the effects of the liquid medium on NSOR and the Verdet constant of Faraday rotation (arising from an external magnetic field) in water, using the recently developed theory applied on a first-principles molecular dynamics trajectory. The gas-to-liquid shifts of the relevant antisymmetric polarizability and, hence, NSOR magnitude are found to be -14% and -29% for (1)H and (17)O nuclei, respectively. On the other hand, medium effects both enhance the local electric field in water and, via bulk magnetization, the local magnetic field. Together these two effects partially cancel the solvation influence on the single-molecular property. We find a good agreement for the hydrogen NSOR with a recent pioneering experiment on H(2)O(l).

Effects of electric field exposure on blood pressure, cardioventilatory activity and the physiological stress response in Arctic char, Salvelinus alpinus L.

Electric field exposure is used to stun or immobilize fish prior to slaughter in the aquaculture industry and for field sampling purposes (i.e. electrofishing), but the physiological response of fish to this exposure is incompletely understood. In this paper we report on changes in blood pressure, heart and ventilation rates, and hematological variables in chronically cannulated Arctic char (Salvelinus alpinus) in response to exposure to an electric field of 4V/cm (125Hz) for 5 and 30s. Both durations of exposure resulted in a brief (total duration: 5.2 to 6.0s, respectively) four-fold blood pressure increase above resting levels. The 5s exposure was followed by a period of cardiac and ventilatory arrest (for 35 and 176s on average, respectively), but cardioventilatory activity recovered in ten out of eleven fish. Nevertheless, signs of systemic stress responses were evident after the exposure. These included moderate hypertension, increased ventilation amplitude, increased plasma cortisol levels and altered hydromineral balance. After the 30s exposure, cardiac activity initially appeared to recover, but subsequently declined. Ventilation did not recover. It is suggested that circulatory failure due to cardiac ischemia resulting from ventilatory failure; rather than instantaneous and irrecoverable cardiac arrest from the electric field exposure per se, is the ultimate cause of death in fish that fail to recover from exposure to an electric field in water. The brief dramatic hypertension observed in char may partly explain the haemorrhages that are frequently observed in electrically stunned fish of some species.

Use of RF electric fields for simultaneous mineral and bio-fouling control in a heat exchanger

The objective of the present study was to investigate the effectiveness of a physical water treatment (PWT) technology using oscillating RF (radio frequency) electric fields in water to mitigate both mineral and bio-fouling in a cooling water application. Heat transfer tests were conducted using a laboratory-scale cooling tower to determine fouling resistance over time, and bio-fouling tests were performed using a heterotrophic plate count method to measure colony forming units (CFU) values per milliliter of cooling water. The results indicated that the present PWT technology could provide an effective mineral fouling prevention by maintaining 90% of the peak heat transfer performance of a heat exchanger, while effectively controlling water-borne microbial organisms.

Effects of electrophoretically deposited carbon nanofibers on the interface of single carbon fibers embedded in epoxy matrix

Electrophoretic deposition (EPD) was used to deposit carboxylic acid-functionalized carbon nanofibers (O-CNFs) on the surface of single carbon fibers. Using the single fiber fragmentation technique and Weibull analysis, interfacial shear strength (IFSS) was estimated for different fiber surface treatments. Samples for sized, unsized, O-CNF deposited sized, and O-CNF deposited unsized carbon fibers were tested. Additionally, the effects of EPD were investigated by testing sized and unsized carbon fiber samples exposed to an electric field in water. Removal of the fiber sizing decreased IFSS by approximately 27%, but addition of O-CNFs to the unsized fiber surface led to an increase of 15% compared to the sized base fiber. The O-CNF deposited sized fibers provided IFSS increases of 207.6% and 66.9% for 1 and 5 min deposition durations, respectively. The surface morphology of all samples was characterized, and those containing homogeneous deposition of closely bound O-CNFs provided the highest IFSS values. Exposing sized fibers to the electric field for 1 min led to an IFSS increase of 79%, while unsized fibers undergoing the same treatment provided increases of 7.7% and 46% compared to the base sized fiber and unsized fiber samples, respectively.

Externally Applied Electric Fields up to 1.6 × 105 V/m Do Not Affect the Homogeneous Nucleation of Ice in Supercooled Water

The freezing of water can initiate at electrically conducting electrodes kept at a high electric potential or at charged electrically insulating surfaces. The microscopic mechanisms of these phenomena are unknown, but they must involve interactions between water molecules and electric fields. This paper investigates the effect of uniform electric fields on the homogeneous nucleation of ice in supercooled water. Electric fields were applied across drops of water immersed in a perfluorinated liquid using a parallel-plate capacitor; the drops traveled in a microchannel and were supercooled until they froze due to the homogeneous nucleation of ice. The distribution of freezing temperatures of drops depended on the rate of nucleation of ice, and the sensitivity of measurements allowed detection of changes by a factor of 1.5 in the rate of nucleation. Sinusoidal alternation of the electric field at frequencies from 3 to 100 kHz prevented free ions present in water from screening the electric field in the bulk of drops. Uniform electric fields in water with amplitudes up to (1.6 ± 0.4) × 10(5) V/m neither enhanced nor suppressed the homogeneous nucleation of ice. Estimations based on thermodynamic models suggest that fields in the range of 10(7)-10(8) V/m might cause an observable increase in the rate of nucleation.

제3전극에 의한 전계변화가 수중 전기물리화학적 특성에 미치는 영향

In this paper, after the third electrode type oxidant generator which could format non-uniform electric field in water had been manufactured and installed, by direct electrolysis, the effects of the hydrogen potential and oxidation reduction potential characteristics attendant upon electric field change on a higher concentration oxidant generation characteristics were investigated. Consequently, as the third electrode was installed in the middle of two slit electrodes and the polarity of applied power was changed, it was observed that the third electrode system with the positive electrode can generate a higher concentration oxidant, hydrogen potential and oxidation reduction potential as compared with that of the negative electrode. It is because the positive electrode was bombarded mostly energetic electrons and the negative electrode was bombarded mainly by less energetic positive ions.