Presence Of External Electric Field Research Articles

Exploring α-synuclein stability under the external electrostatic field: Effect of repeat unit

Parkinson’s disease (PD) is a category of neurodegenerative disorders (ND) that currently lack comprehensive and definitive treatment strategies. The etiology of PD can be attributed to the presence and aggregation of a protein known as α-synuclein. Researchers have observed that the application of an external electrostatic field holds the potential to induce the separation of the fibrous structures into peptides. To comprehend this phenomenon, our investigation involved simulations conducted on the α-synuclein peptides through the application of Molecular Dynamics (MD) simulation techniques under the influence of a 0.1 V/nm electric field. The results obtained from the MD simulations revealed that in the presence of external electric field, the monomer and oligomeric forms of α-synuclein are experienced significant conformational changes which could prevent them from further aggregation. However, as the number of peptide units in the model system increases, forming trimers and tetramers, the stability against the electric field also increases. This enhanced stability in larger aggregates indicates a critical threshold in α-synuclein assembly where the electric field’s effectiveness in disrupting the aggregation diminishes. Therefore, our findings suggest that early diagnosis and intervention could be crucial in preventing PD progression. When α-synuclein predominantly exists in its monomeric or dimeric form, applying even a lower electric field could effectively disrupt the initial aggregation process. Inhibition of α-synuclein fibril formation at early stages might serve as a viable solution to combat PD by halting the formation of more stable and pathogenic α-synuclein fibrils.

General Aspects of Line Shapes in Plasmas in the Presence of External Electric Fields

The present paper discusses a number of topics relevant to line broadening in the presence of periodic oscillatory fields. Specifically, we discuss the applicablility of the expression usually employed to compute the autocorrelation function, the dressing, accounting for random phases, neglecting fine structure and numerical issues associated with stiffnes.

Development of partial denitrification process in upflow-anaerobic sludge blanket and effect of electric field on partial denitrification performance

Partial denitrification (PD) is an alternative to providing NO2– for the anaerobic ammonium oxidation (anammox) process. In this study, three upflow anaerobic sludge blankets (UASB) were used to investigate the effect of an external electric field on PD performance. The results indicated that the maximum nitrite transformation ratio (NTR) reached 76.3 %, with an average NTR of 54.1 %, in the presence of external electric field, whereas the average NTR of the control was only 49.8 %. The fitted maximum specific nitrate reduction rates of PD1, PD2, and PD3 were 83.7, 90.5, and 92.3 mg N g−1VSS h−1, respectively, according to the Haldane model analysis. Microbial community analysis demonstrated that the abundance of Thauera, Comamonas, and Accumulibacter increased with electric assistance. In summary, UASB reactor with electrodes set in the upper region was most feasible for the stable PD process, providing an alternative for developing a coupled PD-anammox process.

Study on the Superlubricity Behavior of Ions under External Electric Fields at Steel Interfaces.

Realizing macroscopic superlubricity in the presence of external electric fields (EEFs) at the steel interfaces is still challenging. In this work, macroscopic superlubricity with a coefficient of friction value of approximately 0.008 was realized under EEFs with the lubrication of LiPF6-based ionic liquids at steel interfaces. The roles of cations and anions in the superlubricity realization under EEFs were studied. Based on the experimental results, the macroscopic superlubricity behavior of Li(PEG)PF6 under EEFs at steel interfaces is attributed to the strong hydration effect of Li+ cations and the complete reactions of anions that contributed to the formation of a boundary film on the appropriate surface. Moreover, the reduction in the number of iron oxides in the boundary film on the disc was beneficial for friction reduction. We also provide a calculation model to describe the relationship between the hydration effect and the optimal voltage position, at which the lowest friction might occur. Ultimately, this work proves that macroscopic superlubricity can be realized under EEFs at steel interfaces and provides a foundation for engineering applications of superlubricity in an electrical environment.

Ion Trapping and Thermionic Emission across Sub-nm Pores.

Ionic transport through a graphene biomimetic subnanometer (sub-nm) pore of arbitrary shape and realistically decorated by intrinsic negatively charged sites is investigated by all-atom molecular dynamics (MD) simulations. In the presence of external electric fields, cation trapping-assisted translocation occurs in the vicinity of the 2D subnanometer pore, while the anion current is blocked by the negative charges. The adsorbed cations in such asymmetrically charged nanopores are located on the top of the nanopore instead of blocking the pore, as suggested previously in highly symmetric pores such as crown ethers. Our analysis of the different types of energy involved in ion translocations indicates that electrostatics is the dominant factor controlling ion transfer across these sub-nm pores. A physical model based on the thermionic emission formalism to account for the free energy barriers to ion flow reproduces the I-V characteristics.

Charges at the heterogeneous interface of dielectrics

The heterogeneous interface of two different dielectrics is commonly observed in diverse electronic devices. Charge emerging will take place at the heterogeneous interface and may greatly influence the device performance. Typically, charge emerging behavior is attributed to the Maxwell–Wagner effect. The emerged charge by the Maxwell–Wagner effect is unipolar. Nevertheless, bipolar phenomena are also frequently observed. This paper reports the change characteristic of accumulated charge between unipolar and bipolar at the heterogeneous interface composed of two different dielectrics. A theoretical analysis is proposed. As an illustration, the laminated membrane is formed by thermally pressing two non-polar polymers, fluorinated ethylene propylene (FEP) and polypropylene (PP). Its interfacial charge nature is studied by means of electret research. It is found that the bipolar charge derives from contact electrification and is determined by the electronegativity of the atoms at two dielectrics’ interface. The unipolar charge originates from the Maxwell–Wagner effect and is determined by the dielectric constant and conductivity of dielectrics. In the absence of external electric field, the charge nature shows bipolar in the form of dipole electric double-layer. In the presence of external electric field, the change of charge nature from bipolarity to unipolarity will occur depending on the electric field and temperature. Its regulation is closely related to the connection mode of external electric field with the heterogeneous interface of dielectrics. When negative electrode is connected with FEP, the charge nature at the interface evolves from bipolarity to positive polarity. When positive electrode is connected with FEP, the charge nature transforms from bipolarity to negative polarity. A critical point exists for a polarizing voltage to induce the change of charge nature.

Correlation between energy band transition and optical absorption spectrum in bilayer armchair graphene nanoribbons

In this work, we investigate the intrinsic as well as modulated optical properties of the AB-stacking bilayer armchair graphene ribbons in the absence and presence of external electric fields. Single-layer ribbons are also considered for comparison. By using a tight-binding model in combination with the gradient approximation, we examine the energy bands, the density of states and the absorption spectra of the studied structures. Our results demonstrate that when external fields are not present, the low-frequency optical absorption spectra display numerous peaks and they vanish at the zero point. In addition, the number, the position, and the intensity of the absorption peaks are strongly associated with the ribbon width. With the wider ribbon width, more absorption peaks are present and a lower threshold absorption frequency is observed. Interestingly, in the presence of electric fields, bilayer armchair ribbons exhibit a lower threshold absorption frequency, more absorption peaks, and weaker spectral intensity. When increasing the strength of the electric field, the prominent peaks of the edge-dependent selection rules are lowered, and the sub-peaks satisfying the extra selection rules come to exist. The obtained results certainly provide a more comprehensive understanding of the correlation between the energy band transition and the optical absorption, in both single-layer and bilayer graphene armchair ribbons, and could provide new insights into developments of optoelectronic device applications based on graphene bilayer ribbons.

Molecular Dynamics Simulation of the Influence of External Electric Fields on the Glass Transition Temperature of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide

We present the results of molecular dynamics simulations of the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2C1im][NTf2] in the presence of external electric fields (EEFs) of varying strengths to understand the effects of EEFs on the glass transition temperature Tg. We compute Tg with an automated and objective method and observe a depression in Tg when cooling the IL within an EEF above a critical strength. The effect is reversible, and glasses prepared with EEFs recover their original zero-field Tg when heated. By examining the dynamics and structure of the liquid phase, we find that the EEF lowers the activation energy for diffusion, reducing the energetic barrier for movement and consequently Tg. We show that the effect can be leveraged to drive an electrified nonvapor compression refrigeration cycle.

Electric fields in a counterflow nonpremixed flame: measurement and simulation

In electric field modified flames, the electric body force on fluid elements can play a role in modifying the flow field, affecting flame characteristics by this modified flow motion. Numerical studies have developed ion kinetic mechanisms and appropriate transport models for charged species, validating them with a voltage-current trend in 1D premixed flames. Recent experimental approaches have measured the electric field by adopting the Electric Field Induced Second Harmonic generation (EFISH) technique. However, the quantification has turned out very challenging due to the inherent distortion in the EFISH signal, as well as inhomogeneous temperature and concentration fields in the combustion field. Here, we propose measurement and calibration schemes to quantify the EFISH signal in a laminar counterflow nonpremixed flame and present comparison with numerical results using an in-house multi-physics CFD (Computational Fluid Dynamics) code. Overall, the quantified electric fields agreed well with those from numerical simulation, specifically capturing null electric fields near the flame in the sub-saturated regime due to the electric field screening effect. In the saturated regime, notable discrepancy was found in a fuel stream when electrons moved through it: experiment indicated a significant number of negative ions in the fuel stream, whereas numerical results predicted negligible negative ions, due to the implemented ion-mechanism. This suggested that the experimentally obtained electric fields may serve as validation data for modeling studies to improve transport models and ion-mechanism. In-situ measurement of charged species in the presence of external electric fields should be a future work.

Electronic Properties of Single‐Layer and Bilayer Graphene Nanoribbons

Herein, a tight‐binding description is utilized to investigate electronic structures and density of states of single‐layer (SL) and bilayer (BL) graphene ribbons with and without the influence of external electric fields. Analyses are implemented to reveal the similarity and difference among electronic properties of three types of structures (specifically SL and BL ribbons with AA and AB stackings). Moreover, both armchair and zigzag edge orientations are considered. It is indicated in the results that variation in electronic properties of these structures in the presence of external electric fields depends on both structural form and edge orientation. The following two points are demonstrated: 1) a transverse field has a significant effect on adjusting bandgap of the zigzag configurations, whereas a vertical electric field has a distinct impact on energy bands of armchair edge structures, and 2) among considered structures, AB‐stacking BL ribbons are invariably the structures that are most strongly influenced by external fields. Interestingly, AB‐stacking BL ribbons are also capable of enlarging bandgap with both edge terminations. Herein, an insight into how the electronic structure and charge distribution of both SL and BL graphene nanoribbons can be controlled not only in armchair but also in zigzag edge terminations using electric stimulants is provided by the results.

Study of Cryogenic Film Boiling in the Presence of External Electric Field Using a Variant of Volume of Fluid-Based Interface Tracking Algorithm

Study of Cryogenic Film Boiling in the Presence of External Electric Field Using a Variant of Volume of Fluid-Based Interface Tracking Algorithm

(Digital Presentation) Electropolymerization of Aromatic Monomers Using Streaming Potentials

Recently, there has been increasing attention on bipolar electrodes which work as a wireless electrode in the presence of external electric field.1 Since bipolar electrodes are driven with low concentration of supporting electrolytes, an electrosynthesis process using bipolar electrode can reduce the amount of waste after the electrolysis. We have already reported the electrochemical fluorination using a bipolar electrode system, in which the amount of supporting electrolyte used could be reduced to less than 1/100 compared to the conventional method.2 On the other hand, when pumping the solution with low concentration of supporting electrolyte into a narrow channel, potential difference between inlet and outlet of the channel, i.e., a streaming potential, generates to potentially be a driving energy for a bipolar electrode system.3 In this study, we have investigated the conditions in a flow cell to generate enough streaming potentials for electrode reactions. Then, electropolymerization of aromatic monomers such as pyrrole and 3,4-ethylenedioxythiophene has been achieved by driving a bipolar electrode using a streaming potential.References N. Shida, Y. Zhou, S. Inagi, Acc. Chem. Res., 2019, 52, 2598–2608.K. Miyamoto, H. Nishiyama, I. Tomita, S. Inagi, ChemElectroChem, 2019, 6, 97–100.I. Dumitrescu, R. K. Anand, S. E. Fosdick, R. M. Crooks, J. Am. Chem. Soc., 2011, 133, 4687–4689. Figure 1

Investigation of boiling process of different fluids in microchannels and nanochannels in the presence of external electric field and external magnetic field using molecular dynamics simulation

The microfluidic systems' thermal performance in various industries is affected by the fluid flow within their micro/nanochannels. This study aimed to investigate the boiling process of samples simulated in micro/nanochannel by molecular dynamics simulation. In the present study, the boiling time inside the micro/nanochannel is investigated at different types of base fluid (Helium, oxygen (air), and water), different types of channels walls particles (copper, platinum, and copper/platinum), number of atomic curvatures (1, 2, and 3), external electric field (1, 2, and 5 V/m), and external magnetic fields (1, 2, and 5 T). Numerically, the phase change rate in Helium base fluid samples is higher than other fluids. Its boiling time in micro/nanochannels was 3.88 and 3.54 ns, respectively. This indicates an increase in these structures' efficiency in constructing heat transfer processes. In addition, the boiling time of the base fluid in the platinum atomic micro/nanochannels occurs in a shorter time of 3.61 and 3.52 ns. By increasing the number of curves from 1 to 3 complete curvatures, the micro/nanochannel's boiling time decreases from 3.88/3.54 to 3.07/2.89 ns. Also, by increasing the intensity of the external electric field from 0 to 5 V/m, the boiling time in the micro/nanochannel decreases from 3.88/3.84 ns to 3.21/3.16 ns. Finally, increasing the intensity of the external magnetic field from 0 to 5 T leads to a decrease in boiling time in the micro/nanochannel to 3.10/3.02 ns. This phenomenon indicates an increase in mobility and kinetic energy of the base fluid by applying the external field.

Specific Features of Recombination Radiation in Quantum Dots with the A+ + e Impurity Complexes in the Presence of External Electric Field. Part I. Effect of External Electric Field on the Binding Energy of a Hole in the A+ + e Impurity Complex in a Spherically Symmetric Quantum Dot

Specific Features of Recombination Radiation in Quantum Dots with the A+ + e Impurity Complexes in the Presence of External Electric Field. Part I. Effect of External Electric Field on the Binding Energy of a Hole in the A+ + e Impurity Complex in a Spherically Symmetric Quantum Dot

Specific Features of Recombination Radiation in Quantum Dots with the A+ + e Impurity Complexes in the Presence of External Electric Field. Part II. Quantum-Size Stark Effect in the Spectra of Recombination Radiation of Quantum Dots with the A+ + e Impurity Complex

Specific Features of Recombination Radiation in Quantum Dots with the A+ + e Impurity Complexes in the Presence of External Electric Field. Part II. Quantum-Size Stark Effect in the Spectra of Recombination Radiation of Quantum Dots with the A+ + e Impurity Complex

Existence in the nonlinear Schrödinger equation with bounded magnetic field

The paper studies existence of ground states for the nonlinear Schrödinger equation 0.1 $$\begin{aligned} -(\nabla + {\mathbf {i}}A(x))^2u+V(x)u=|u|^{p-1}u ,\quad 2<p<2^*, \end{aligned}$$ with a general external magnetic field. In particular, no lattice periodicity or symmetry of the magnetic field, or presence of external electric field is required.

About the time evolution of coherent electron states in monolayers of boron allotropes

In this paper, we theoretically analyze the massless Dirac fermion dynamics in twodimensional monolayers of boron allotropes, 8B and 2BH − pmmn borophene, interacting with external electric and magnetic fields. We study the effect of the Dirac cone tilt in these materials, which is known as valley index, through the time evolution of probability density of coherent electron states as well as their phase-space representation obtained via the Wigner function. Our results show that the time evolution of the coherent electron states in these materials is valley dependent, which is reinforced in the presence of external electric fields.

Catalysis and inverse electric catalysis in a scalar theory

In this article we explore the phase diagram associated to the symmetry breaking of a scalar self-interacting theory, induced by temperature and the presence of an external electric field. For such purpose, first we obtain the boson propagator, in the presence of a constant external electric field, both in the weak and strong field strength limits. Novel expansions are derived for the effective potential, valid for the whole range of temperature. We found inverse electric catalysis for the weak field region, i.e., a situation where the critical temperature diminishes as function of the strength of the electric field whereas for a strong field electric catalysis emerges. These behaviors, in the weak and strong intensity sectors, are valid for all possible values of temperature.

Investigation of Dipolar Response of the Hydrated Hen-Egg White Lysozyme Complex under Externally Applied Electric Fields: Insights from Non-equilibrium Molecular Dynamics.

Given its ubiquitous presence in the environment of bio-macromolecules, water is well known to play a fundamental part in biological activity, often as a regulating agent. In parallel, with increasing attention focused on the potential damage of microwave-frequency radiation exposure to human health, the effects of extraneous electric and electromagnetic (e/m) fields on water shells surrounding proteins, and, indeed, biomolecules themselves, are becoming a particularly pertinent issue. In this study, non-equilibrium molecular dynamics simulations of hydrated hen-egg white lysozyme have been performed in both the absence and presence of external electric fields of varying intensity (0.005–0.02 V/Å) and frequency (static, i.e., zero-frequency, together with oscillating fields of 2.45–100 GHz). By comparing the effect of different electric-field conditions on both the protein’s and surrounding hydration layer’s dipole moments and their underlying relaxation dynamics, clear and evident non-thermal field effects were observed on the dipolar response of both the protein and hydration layer. This occurred primarily as a consequence of the protein’s dipolar alignment with the external field and increased with the growth of field intensity. In addition, it was found that the lag time of dipolar response to the applied field itself, for both the protein and the first hydration sub-shell (i.e., directly adsorbed layer), under oscillating fields is longer than that in both the second hydration sub-layer and bulk water, owing to strong direct protein–water adsorption. In that respect, we also probe and discuss the effect of protein–water hydrogen bonds, dissecting the subtleties of “bio-water” dipolar response.

Laser-assisted synthesis of Ag–Cu alloy nanoparticles with tunable surface plasmon resonance frequency in presence of external electric field

The present study aimed to synthesize the colloidal Ag–Cu alloy nanoparticles (NPs) in the presence of an external electric field. Synthesis of Ag–Cu alloy NPs is important because of their unique properties for antibacterial and antimicrobial activities. Colloidal Ag and Cu NPs were produced individually with nanosecond pulsed laser ablation in distilled water and were mixed in equal volume. The mixed colloid was postirradiated in the presence of an external DC electric field. The obtained colloidal NPs were characterized using various diagnostic methods. The results of this study demonstrated the long-term stability and oxidation resistance of colloidal Ag–Cu alloy NPs compared to the Ag and Cu NPs. Also, the results of this study showed that the external electric field reduces the average size of alloy NPs, and tune the surface plasmon resonance frequency.