Charge Contribution Research Articles

Charged wormhole solutions in 4D Einstein-Gauss-Bonnet gravity

In the present work, we construct models of static wormholes in 4-dimensional Einstein-Gauss-Bonnet (4D EGB) gravity with an (an)isotropic energy momentum tensor (EMT) and a Maxwell field as supporting matters for the wormhole geometry assuming a constant redshift function. We obtain exact spherically symmetric wormhole solutions in 4D EGB gravity for isotropic and anisotropic matter sources under the effect of electric charge. The solutions are more generalized in the sense of incorporating the charge contributions. Furthermore, we examine the null, weak and strong energy conditions at the wormhole throat of radius r=r0. We demonstrate that at the wormhole throat, the classical energy conditions are violated by arbitrary small amount. Additionally, we analyze the wormhole geometry incorporating semiclassical corrections through embedding diagrams. We discover that the wormhole solutions are in equilibrium as the anisotropic and hydrostatic forces cancel each other.

Flexible High‐Temperature Polymer Dielectrics Induced by Ultraviolet Radiation for High Efficient Energy Storage

AbstractPolymer‐based dielectrics with fast electrostatic energy storage and release, are crucial for advanced electronics and power systems. However, the deterioration of insulation performance and charge–discharge efficiency of polymer dielectrics at elevated temperatures and high electric fields hinder the applications of capacitors in harsh environments. Herein, a facile and scalable approach is reported to fabricating flexible high‐temperature polymer dielectrics for high‐efficiency energy storage by ultraviolet irradiation. The resultant dielectric films exhibit an augment of 493% in energy density and exceeding 800% in discharge efficiency at 200 °C (3.2 J cm−3 and over 90% discharge efficiency at 480 M V−1m for irradiated polyetherimide (PEI), 0.54 J cm−3, and below 10% discharge efficiency at 400 MV m−1 for pristine PEI) and excellent cycle performance. The injected space charge is found to be the dominant contributor to energy loss during the charge–discharge process. Free radicals introduced by ultraviolet irradiation can act as deep traps to capture injected charge and suppress space charge migration. This work clarifies the contribution of space charge to energy loss and demonstrates the effectiveness of ultraviolet irradiation in improving the capacitive performance of high‐temperature polymer dielectrics. These findings provide a novel paradigm for the rational design of high‐temperature polymer dielectrics for high‐efficiency energy storage.

Photoresponse enhancement mechanism of CuInP2S6-based device by coupling piezo-phototronic effect and ferroelectric polarization and its application of architecture monitoring

With the arrival of the information society, multifunctional integrated devices based on two-dimensional (2D) materials are crucial for promoting advanced technology. However, the impact of coupling of various physical effects on their performance remains unexplored. Herein, the influence of coupling of piezoelectricity, photoexcitation and ferroelectricity within 2D ferroelectric CuInP2S6 (CIPS), that is, the piezo-phototronic effect and the bulk photovoltaic effect, on the device photoelectric performance have been investigated. Our experiments show that the piezo-phototronic effect can improve the photoelectric performance of the poled devices by 1.36 times, and ferroelectric polarization in turn increases the impact of the piezo-phototronic effect on the performance of the poled devices by 3.8 times. Systematically band diagram analysis reveals that this mutual enhancement mechanism can be attributed to the contribution of piezoelectric polarization charges and Cu+ ions movement to carrier migration, which was supported by Kelvin probe force microscope, STEM, and first-principles calculations. Furthermore, an architecture monitoring system based on a CIPS device was constructed to detect building tilt in real-time. Our work provides a paradigm for enhancing the photoelectric performance of 2D ferroelectrics and has profound significance in investigating multi-physics effects coupling mechanisms in a single material.

Interplay between charge and spin noise in the near-surface theory of decoherence and relaxation of C3v symmetry qutrit spin-1 centers

Decoherence and relaxation of solid-state defect qutrits near a crystal surface, where they are commonly used as quantum sensors, originate from charge and magnetic field noise. A complete theory requires a formalism for decoherence and relaxation that includes all Hamiltonian terms allowed by the defect's point-group symmetry. This formalism, presented here for the C3v symmetry of a spin-1 defect in a diamond, silicon carbide, or similar host, relies on a Lindblad dynamical equation and clarifies the relative contributions of charge and spin noise to relaxation and decoherence, along with their dependence on the defect spin's depth and resonant frequencies. The calculations agree with the experimental measurements of Sangtawesin [], and corroborate the importance of charge noise. Published by the American Physical Society 2024

Magnetic corrections to the QCD coupling: Strong field approximation

We compute the one-loop vertex function of the QCD coupling in the presence of an ultraintense magnetic field. From the vertex function, we extract the effective coupling and show that it grows with increasing magnetic field. We consider the quark-gluon vertex and the three-gluon vertex, accounting for the propagators of charged particles within the loops using the lowest Landau level approximation in order to satisfy the condition where the magnetic field is the largest energy scale. Under this approximation, we find that the contribution from the three-gluon vertex vanishes. Therefore, this result arises from the competition between the color charge associated to gluons and to quarks as well, with the former being larger than the latter. The behavior of the QCD coupling as a function of the magnetic field strength is analogous to that exhibited by the light-quark condensate, indicating the magnetic catalysis occurs. This increasing behavior stems from the dominant contribution of color charge associated to gluons in the vertex function. Published by the American Physical Society 2024

A lepton model with nearly Cobimaximal mixing

Cobimaximal mixing predicts π/4 and 3π/2 for the atmospheric angle and the Dirac CP-violating phase, respectively. These values are in tension with the neutrino global fits. If this pattern was behind the lepton mixings, then it would have to be broken. In that case, in this paper, we explore the S3 flavor symmetry within the B − L gauge model where the aforementioned scheme comes from the neutrino sector but the charged lepton contribution breaks the well known predictions so the mixing observables as well as the mee mass can be accommodated quite well according to the available data. Notably, the predicted regions for the Dirac CP-violating phase would allow us to test the model in future experiments.

High-temperature modifications of charged Casimir wormholes

In this work, we extend the investigation of the consequences of thermal fluctuations on the Casimir effect within the context of a traversable wormhole, recently proposed by Garattini & Faizal, arXiv:2403.15174 [gr-qc], subject to charge contributions. Specifically, we focus on scenarios where the plates exhibit both constant and radial variations. In our analysis, we initially concentrate on the high temperature approximation, considering solely the influence of charge on the thermal Casimir wormholes. Additionally, upon incorporating Generalized Uncertainty Principle (GUP) corrections to the Casimir energy, we obtain a new class of wormhole solutions. Notably, we establish that the flare-out condition remains consistently satisfied. Intriguingly, our findings reveal that both the charge and GUP contributions serve to further enlarge the throat's size in the radial variation.

A 3HDM with Z[formula omitted] Z[formula omitted] model for nearly co-bimaximal mixing

We suggest a combination of Z4⋊Z4 symmetry with the B−L gauge model in the framework of three-Higgs-doublet model (3HDM). The co-bimaximal mixing pattern is broken by the charged lepton contribution which can accommodate the global analysis of neutrino oscillation data. The tiny of the light neutrino masses and neutrino mass hierarchy are produced by the type-I seesaw mechanism. The charged-lepton mass hierarchy is naturally achieved and the constraints on the efictive neutrino masses are in good agreement with the recent experimental bounds.

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations.

Triboelectrification is a ubiquitous and poorly understood phenomenon in powder processing, particularly for pharmaceutical powders. Charged particles can adhere to vessel walls, causing sheeting; they can also cause agglomeration, threatening the stability of powder formulations, and in extreme cases electrostatic discharges, which present a serious fire and explosion hazard. Triboelectrification is highly sensitive to environmental and material conditions, which makes it very difficult to compare experimental results from different publications. In this work, density functional theory (DFT) is used to investigate the charge transfer characteristics of several functional groups of paracetamol in order to better understand the mechanisms of charging at the nanoscale and the influence of the environmental and material properties on charge transfer. This is achieved by studying the structure and electronic properties at the molecule-substrate interface. Using this molecule-substrate approach, the charging contributions of individual functional groups are explored by examining the Hirschfeld charges, the charge density difference between the molecule and substrate, the density of states, and the location of the frontier orbitals (HOMO and LUMO) of a paracetamol molecule. Charge density difference calculations indicate a significant transfer of charge from the molecule to the surface. Observable regions of electron density enrichment and depletion are evident around the electron-donating and -withdrawing groups, respectively. The density of states for the paracetamol molecule evolves as it approaches the surface, and the band gap disappears upon contact with the substrate. Hirshfeld charge analysis reveals asymmetry in the charge redistribution around the molecule, highlighting the varying charging tendencies of different atoms.

Opto-electrochemical variation with gel polymer electrolytes in transparent electrochemical capacitors for ionotronics

Advanced flexible ionotronic devices have found excellent applications in the next generation of electronic skin (e-skin) development for smart wearables, robotics, and prosthesis. In this work, we developed transparent ionotronic-based flexible electrochemical capacitors using gel electrolytes and indium tin oxide (ITO) based transparent flexible electrodes. Different gel electrolytes were prepared using various salts, including NaCl, KCl, and LiCl in a 1:1 ratio with a polyvinyl alcohol (PVA) solution and compared its electrochemical performances. The interaction between gel electrolytes and ITO electrodes was investigated through the development of transparent electrochemical capacitors (TEC). The stable and consistent supply of ions was provided by the gel, which is essential for the charge storage and discharge within the TEC. The total charge contribution of the developed TECs is found from the diffusion-controlled mechanism and is measured to be 4.59 mC cm−2 for a LiCl/PVA-based gel. The prepared TEC with LiCl/PVA gel electrolyte exhibited a specific capacitance of 6.61 mF cm−2 at 10 μA cm−2. The prepared electrolyte shows a transparency of 99% at 550 nm and the fabricated TEC using LiCl/PVA gel exhibited a direct bandgap of 5.34 eV. The primary benefits of such ionotronic-based TEC development point to its potential future applications in the manufacturing of transparent batteries, electrochromic energy storage devices, ionotronic-based sensors, and photoelectrochemical energy storage devices.

Unveiling the influence of various vacancies on the mechanical properties of Ti4C3O2

Two-dimensional transition metal carbides and nitrides are widely recognized as potential candidates in areas such as energy storage and sensors. In this work, we explore the mechanical properties of Ti4C3O2 with a perfect cell and Ti4C3O2 with vacancies by a first-principles method. The results indicate that the loss of C in the outer layer of Ti4C3O2 is more likely to occur due to the smaller formation energy of C-vacancy. By considering the charge contribution, the removed atom changes the valence electron equilibrium concentration between that atom and its neighbors, which in turn affects the mechanical properties of Ti4C3O2. The presence of various vacancies affects the strength of the TiO bonds on the shear plane, causing Ti4C3O2 to exhibit changes towards brittleness or ductility. It is noteworthy that the elastic modulus, critical strain, and ideal stress of Ti4C3O2 with different concentrations of O vacancies are all approximately the same, suggesting that the variations in their mechanical properties are not significant for Ti4C3O2 with different degrees of O functional group coverage. Our findings offer valuable insights for the development of MXene-based nanoflexible energy storage devices, gas-sensitive sensors, high-temperature environmental applications, and beyond.

Intrinsic and extrinsic contributions in the ferroelectric response of chemically synthesized BiFeO3-xPbTiO3 thin films

Multiferroic (BiFeO3)1−x-(PbTiO3)x (1−x)BF−xPT thin films exhibit very high electromechanical properties in the vicinity of the morphotropic phase boundary (MPB), making them important candidates for use in several modern device applications. However, preparing high-quality (1−x)BF−xPT thin films is challenging due to the high conductivity caused by oxygen vacancies produced during the synthesis process. This study aims to understand the effect of size and porosity density on the electrical properties of (1−x)BF−xPT thin films. A series of (1−x)BF−xPT solid solution thin films were fabricated using the spin-coating method on Pt/TiO2/SiO2/Si(100) substrates through chemical solution deposition. X-ray diffraction studies revealed a polycrystalline structure. Surface SEM images showed that the films have a uniform surface with average grain sizes ranging between 50 and 200 nm and an average film thickness of 1.5 μm. A decrease in average pore size and an increase in the number of pores were observed with the increase in PT concentration in the prepared films. Ferroelectric characterization revealed that the films exhibit room-temperature ferroelectric hysteresis loops. Sources of various contributions to polarization were extracted from hysteresis loops, including true ferroelectric switching and space charge contributions. Thin films with 0.30 < x < 0.45 show higher remanent and saturation polarization values, suggesting that these compositions exhibit the MPB. The highest remanent polarization value (PR = 16.68 μC/cm2) was observed for the thin film with x = 0.40. The correlation between the phase, composition, film morphology, and ferroelectric response is described and discussed.

Constructing Hopf insulator from geometric perspective of Hopf invariant

Abstract We propose a method to construct Hopf insulators based on the study of topological defects from the geometric perspective of Hopf invariant $I$. Firstly, we prove two types of topological defects naturally inhering in the inner differential structure of the Hopf mapping. One type is the four-dimensional (4D) point defects, which lead to a topological phase transition occurs at the Dirac points. The other type is the three-dimensional (3D) merons, whose topological charges give the evaluations of $I$. Then, we show two ways to establish the Hopf insulator models. One approach is to modify the locations of merons, thereby the contributions of charges to $I$ will change. The other approach is related to the number of defects. It is discovered that $I$ will decrease if the number reduces, while increase if additional defects are added. The method developed in this paper is expected to provides a new perspective for understanding the topological invariants, which opens a new door in exploring and designing novel topological materials in three dimensions.

Cellulose nanofibrils-stabilized food-grade Pickering emulsions: Clarifying surface charge's contribution and advancing stabilization mechanism understanding

Pickering emulsions stabilized by cellulose nanofibrils (CN) have sparked significant attention, however the fundamental mechanisms underpinning the stabilization process remain insufficiently elucidated. Focusing on an academic debate of surface charge's contribution to stabilization, this study first explored how the varying carboxyl group contents of TEMPO-oxidized CN (TCNs) impacted Pickering emulsions' formation and stability. TCNs with 662 μmol/g carboxyl groups exhibited distinctive attributes, including larger particle sizes (322 nm in length), improved thermal stability (maximum decomposition temperature of 317 °C), and increased viscosity (1.57 Paִִ⋅s) compared to their counterparts with 963–1011 μmol/g charge density. Notably, the former one, with a larger three-phase contact angle (51.5°), higher interfacial tension, and greater detachment energy (21.69 × 10−18 J), resulted in a homogeneous dispersion of spherical oil droplets and super-stable Pickering emulsions with a consistent emulsifying index of 100% over 30 days. These findings clearly clarified that TCNs with a lower charge density exhibit superior emulsifying properties. In addition, for the first time, a distinct oil droplet-decorated fibrillar structure was observed, probably suggesting that TCNs might be able to serve as anchoring matrixes to guide the distribution of oil droplets. These structures seemed to impeded the migration and accumulation of the oil droplets, consequently enhancing the stability of the resulting Pickering emulsions. To sum, this study clearly elucidated the role of surface charge in stabilizing cellulose-based Pickering emulsions and proposed a new model to expound the cellulose-oil interaction mechanisms, thus providing new theoretical and practical insights on utilization of CN as highly effective emulsifier for super-stable food-grade Pickering emulsions.

Unveiling the heavy-metal ion critical role in γ-dicalcium silicate: from solidification to early hydration.

The heavy-metal ion critical role in γ-dicalcium silicate (γ-C2S) both in terms of solidification mechanism and hydration is still unclear. In this work, the solidification mechanism and the effect on initiating hydration of these three heavy-metal ions (Ba, Cd, and Cr) in γ-C2S is systemically studied by well-defined ab initio calculations. The calculated results show that the solid solution tendency of ions originates from the charge contribution, and the charge localization caused by the doping of Cr ions weakens the surface water adsorption. These insights will provide theoretical guidance for the low-carbon cement development by γ-C2S.

Analyzing the charge contributions of metal-organic framework derived nanosized cobalt nitride/carbon composites in asymmetrical supercapacitors.

Metal-organic framework derived nanostructures have recently received research attention owing to their inherent porosity, stability, and structural tailorability. This work involves the conversion of zeolitic imidazolate frameworks (ZIFs) into cobalt nitride nanoparticles embedded within a porous carbon matrix (Co4N/C). The as-prepared composite shows great synergy by providing a high surface area and efficient charge transfer, showcasing outstanding electrochemical performance by providing a specific capacitance of 313 F g-1. Moreover, we meticulously conducted calculations to derive the most precise values for the surface contribution, a crucial aspect often overlooked in existing literature, thereby ensuring the reliability of our calculated measurements. Correct calculations of surface and diffusion charge contributions are necessary for evaluating the overall electrochemical performance of supercapacitors. For practical utility, we successfully assembled an asymmetrical supercapacitor employing the Co4N/carbon composite as the negative electrode that achieved an impressive energy density of 26.6 W h kg-1 at a power density of 0.36 kW kg-1. This study opens up new avenues for investigating the use of other metal nitride nanoparticles embedded in carbon structures for various energy storage applications.

The Contribution of Artificial Charging in Optimal Exploitation of Water Resources, Isfahan, Iran

The Contribution of Artificial Charging in Optimal Exploitation of Water Resources, Isfahan, Iran

A highly stable full-polymer electrochemical deionization system: dopant engineering & mechanism study.

Electrochemical deionization (ECDI) has emerged as a promising technology for water treatment, with faradaic ECDI systems garnering significant attention due to their enhanced performance potential. This study focuses on the development of a highly stable and efficient, full-polymer (polypyrrole, PPy) ECDI system based on two key strategies. Firstly, dopant engineering, involving the design of dopants with a high charge/molecular weight (MW) ratio and structural complexity, facilitating their effective integration into the polymer backbone. This ensures sustained contribution of strong negative charges, enhancing system performance, while the bulky dopant structure promotes stability during extended operation cycles. Secondly, operating the system with well-balanced charges between deionization and concentration processes significantly reduces irreversible reactions on the polymer, thereby mitigating dopant leakage. Implementing these strategies, the PPy(PSS)//PPy(ClO4) (PSS: polystyrene sulfonate) system achieves a high salt removal capacity (SRC) of 48 mg g-1, an ultra-low energy consumption (EC) of 0.167 kW h kgNaCl-1, and remarkable stability, with 96% SRC retention after 104 cycles of operation. Additionally, this study provides a detailed degradation mechanism based on pre- and post-cycling analyses, offering valuable insights for the construction of highly stable ECDI systems with superior performance in water treatment applications.

Estimation of the electrochemical active site density of a metal-free carbon-based catalyst using phosphomolybdate (PMo12) as an adsorbate.

A method to estimate the electrochemical active site density (SD) of carbon (C) and nitrogen-doped carbon (N/C-900) using phosphomolybdate (PMo12) as a probe molecule is proposed. The complete coverage of the active sites by the probe molecules is established irrespective of the adsorbate concentration (1, 5, or 10 mM), potential cycling (1 or 10 cycles) and cleaning time (2, 5, or 10 min). A conversion factor derived from a smooth and polished glassy carbon disk of known geometrical area is used to estimate the electrochemical active surface area (ECSA) of the carbon catalyst from the SD. The relatively higher SD values estimated from DC voltammetry than from large-amplitude Fourier-transform alternating-current voltammetry (FTacV) is indicative of the contribution of capacitive charge in the former. Adsorbed probe molecules (PMo12) can readily be desorbed from the catalyst surface by cycling the electrode to lower potentials. The active site density of N/C-900 (∼0.36 × 1019 sites g-1) is higher than that of C (∼0.17 × 1019 sites g-1).

Mechanistic insights of electrocatalytic CO2 reduction by Mn complexes: synergistic effects of the ligands.

The electrocatalytic mechanisms of CO2 reduction catalyzed by pyridine-oxazoline (pyrox)-based Mn catalysts were investigated by DFT calculations. In-depth comparative analyses of pyrox-based and bipyridine-based Mn complexes were carried out. C-OH cleavage is the rate-determining step for both the protonation-first path and the reduction-first path. The free energy of CO2 activation (ΔG1) and the electrons donated by CO ligands in this step are effective descriptors in regulating the C-OH cleavage barrier. The reduction of carboxylate complex 6 (E6) is the potential-determining step for the reduction-first path. Meanwhile, for the protonation-first path, the initial generation (E2) or the regeneration (E8) of active catalyst might be potential-determining. Hirshfeld charge and orbital contribution analysis indicate that E6 is definitely based on the heterocyclic ligand and E2 is related to both the heterocyclic ligand and three CO ligands. Therefore, replacement of the CO ligand by a stronger electron donating ligand can effectively boost the catalytic activity of CO2 reduction without increasing the overpotential in the reduction-first path. This hypothesis is supported by the mechanism calculations of the Mn complex in which the axial CO ligand is replaced by a pyridine or PMe3.