Charge Distribution Of Ions Research Articles

Modified Debye-Hückel-Onsager theory for electrical conductivity in aqueous electrolyte solutions: Account of ionic charge nonlocality.

This paper presents a mean field theory of electrolyte solutions, extending the classical Debye-Hückel-Onsager theory to provide a detailed description of the electrical conductivity in strong electrolyte solutions. The theory systematically incorporates the effects of ion specificity, such as steric interactions, hydration of ions, and their spatial charge distributions, into the mean-field framework. This allows for the calculation of ion mobility and electrical conductivity, while accounting for relaxation and hydrodynamic phenomena. At low concentrations, the model reproduces the well-known Kohlrausch's limiting law. Using the exponential (Slater-type) charge distribution function for solvated ions, we demonstrate that experimental data on the electrical conductivity of aqueous 1:1, 2:1, and 3:1 electrolyte solutions can be approximated over a broad concentration range by adjusting a single free parameter representing the spatial scale of the nonlocal ion charge distribution. Using the fitted value of this parameter at 298.15K, we obtain good agreement with the available experimental data when calculating electrical conductivity across different temperatures. We also analyze the effects of temperature and electrolyte concentration on the relaxation and electrophoretic contributions to total electrical conductivity, explaining the underlying physical mechanisms responsible for the observed behavior.

Numerical study on staggered needle-plate electrode configuration for improved particulate matter collection in electrostatic precipitator

The electrostatic precipitator (ESP) utilizes corona discharge to effectively separate particles from polluted air. The arrangement of electrode is a crucial role in achieving higher efficiency. Needle discharge electrodes can generate concentrated corona discharge at lower applied voltages. In this study, a staggered needle-plate electrode configuration was presented to expand the domain for particle charging, and thereby improve collection efficiency. A three-dimensional model was established to describe the multi-physics phenomenon in the ESP. The ion charge distribution, electric field, and particle collection efficiency were investigated under various conditions. The staggered model showed an average ion charge density that was 20% higher than that of the aligned arrangement. Particles introduced via staggered model acquired higher charge and showed improved collection efficiency across inflow velocities of 0.5 to 1.5 m/s and particle diameters of 0.1 to 50 μm. In the staggered model, particles predominantly escaped near the sidewall of the ESP.

Anions mediated electron-rich metalloporphyrin ionic framework as recyclable catalyst for conversion of urea into cyclic carbonates

As CO2 typical derivative, urea has the potential to be uniquely economical and green raw materials in generating cyclic carbonates via alcoholysis. Nonetheless, the existing processes for obtaining cyclic carbonates from urea alcoholysis reaction pose considerable challenges in achieving efficient catalyst recycling. Functional organic heterogeneous compounds are emerging materials for catalysis and enhanced reusability due to their large number of coordination sites, but they still fall short of effectively modulating the charge distribution of metal ions. Herein, drawing inspiration from the capacity of ionic liquids (ILs) to effectively control the distribution and transfer of spatial charges within materials, metalloporphyrin ionic framework catalysts were developed by combining metal ions and ILs for the transformation of urea into cyclic carbonates. This heterogeneous catalyst, featuring an adjustable structure and stable metal coordination sites on its surface, exhibits remarkable stability, resulting in a 2.7-fold reduction in catalyst dosage compared to other reported supported catalysts. Based on detailed experiments and DFT calculations, this tunable performance can be mainly explained by the effect of porphyrin zinc (II) and IL anions via molecular engineering. These atom-economical transformations provide a direct and selective access to valuable compounds from cheap and available urea using an efficient organic heterogeneous catalyst.

Self–dual solutions of a field theory model of two linked rings

In this work the connection established in [7,8] between a model of two linked polymers rings with fixed Gaussian linking number forming a 4-plat and the statistical mechanics of non-relativistic anyon particles is explored. The excluded volume interactions have been switched off and only the interactions of entropic origin arising from the topological constraints are considered. An interpretation from the polymer point of view of the field equations that minimize the energy of the model in the limit in which one of the spatial dimensions of the 4-plat becomes very large is provided. It is shown that the self-dual contributions are responsible for the long-range interactions that are necessary for preserving the global topological properties of the system during the thermal fluctuations. The non self-dual part is also related to the topological constraints, and takes into account the local interactions acting on the monomers in order to prevent the breaking of the polymer lines. It turns out that the energy landscape of the two linked rings is quite complex. Assuming as a rough approximation that the monomer densities of half of the 4-plat are constant, at least two points of energy minimum are found. Classes of non-trivial self-dual solutions of the self-dual field equations are derived. One of these classes is characterized by densities of monomers that are the squared modulus of holomorphic functions. The second class is obtained under some assumptions that allow to reduce the self-dual equations to an analog of the Gouy-Chapman equation for the charge distribution of ions in a double layer capacitor. In the present case, the spatial distribution of the electric potential of the ions is replaced by the spatial distribution of the fictitious magnetic fields associated with the presence of the topological constraints. In the limit in which two of the spatial dimensions are large in comparison with the third one, we provide exact formulas for the conformations of the monomer densities of the 4-plat by using the elliptic, hyperbolic and trigonometric solutions of the sinh-Gordon and cosh-Gordon equations which have been used for instance in the construction of classical string solutions in AdS3 and dS3 [9].

Waterborne polyurethanes with novel chain extenders bearing multiple sulfonate groups

The anionic chain extenders used in waterborne polyurethane (WPU) generally contain one anionic ion per extender. Increasing its content in WPU makes the WPU emulsion more stable, however also makes the WPU film more water sensitive, which is a dilemma needed to be solved. Herein, a novel class of anionic chain extenders bearing two or foursulfonate groups is rationally designed. The ion strength of chain extender is thus enhanced and the distribution of ionic charges on the resulting WPU is also altered. The relationship between the structure of the chain extenders and the properties of WPU is studied systematically. The results show that the critical percentage of the anionic extender needed to for stable WPU emulsion is reduced in a nonproportional way with the increase of the number of anionic groups per extender. For example, while the critical percentage of the chain extender for stable emulsion formation for aliphatic-type chain extender containing two sulfonates is 6 mol%, that for chain extender containing four sulfonates is only 2 mol%. Hence the overall hydrophilic segments on the WPU backbone is greatly decreased, which make the WPU more water resistant without sacrificing the emulsification capability of WPU. Among them, the threshold to form stable emulsion for WPU made from the ether-type chain extender containing four sulfonates is as low as 1.2 mol%, and the water absorption of the resultant film is only 3.5 %. The resulting WPU films show strong adhesion to various surfances and excellent resistance toward abrasion. This provides a new strategy to balance the emulsification capability and water-resistence property of WPU.

ZnO@C Coated Cellulose-Based Separators Control Lithium Deposition Direction to Stable Lithium Metal Batteries.

Li metal anodes have attracted attention due to their high specific capacity and low electrochemical potential. Nevertheless, the uncontrolled growth of Li dendrites hinders the practical application of Li metal batteries. Although the various approaches have made performance improvements, safety hazards still exist since Li dendrites are still growing along the anode to the separator during the continuous plating/stripping process. Herein, a straightforward method is proposed to achieve stable Li metal batteries with directional growth control by using a functional ZnO@C/cellulose membrane as a separator. The abundant pore structure and functional groups of biomass cellulose enhance the Li-ion transport and interface compatibility. The ZnO transforms in situ to form a Li-Zn alloy layer which is uniformly coated to the separator to direct uniform ion concentration polarization and charge distribution polarization, control the growth direction of Li, significantly improve the cycling stability, and promote the reversibility of the Li plating/exfoliation process. As a result, the symmetric cell exhibits an extreme lifetime of more than 4500h and low polarization at 3mAcm-2 . The cycling performance of the Li||LiFePO4 full cell reaches a capacity retention of 98% after 270 cycles at a mass loading of 10mgcm-2 .

Electrical properties of tissues from a microscopic model of confined electrolytes

Objective. In the presence of oscillatory electric fields, the motion of electrolyte ions in biological tissues is often limited by the confinement created by cell and organelle walls. This confinement induces the organization of the ions into dynamic double layers. This work determines the contribution of these double layers to the bulk conductivity and permittivity of tissues. Approach. Tissues are modeled as repeated units of electrolyte regions separated by dielectric walls. Within the electrolyte regions, a coarse-grained model is used to describe the associated ionic charge distribution. The model emphasizes the role of the displacement current in addition to the ionic current and enables the evaluation of macroscopic conductivities and permittivities. Main results. We obtain analytical expressions for the bulk conductivity and permittivity as a function of the frequency of the oscillatory electric field. These expressions explicitly include the geometric information of the repeated structure and the contribution of the dynamic double layers. The low-frequency limit of the conductivity expression yields a result predicted by the Debye permittivity form. The model also provides a microscopic interpretation of the Maxwell–Wagner effect. Significance. The results obtained contribute to the interpretation of the macroscopic measurements of electrical properties of tissues in terms of their microscopic structure. The model enables a critical assessment of the justification for the use of macroscopic models to analyze the transmission of electrical signals through tissues.

Investigation of Multi-ionization Processes of Kr and Xe Using Short-pulse X-rays and Time-of-flight Apparatus

The multi-ionization processes of Kr and Xe in the K-edge photon energy region were investigated using short-pulse x-rays and time-of-flight apparatus. The generation of Kr13+ ions in this photon energy region was observed for the first time. The distribution characteristics observed in the experiment, such as the production of Kr13+ ions, high production ratios of Kr4+, Kr5+, and Kr6+ ions, and the existence of a small peak for Kr8+, were quantitatively reproduced by the Monte Carlo simulation for the charge distribution of Kr ions following 1s of inner shell ionization. The highly charged ions were suppressed in the experiments compared with those in the simulation, probably owing to the inhibition of certain Coster-Kronig processes in the highly charged ions, which were not considered for analysis. The charge distribution of Xe ions following 1s of inner shell ionization was also investigated. A similar charge distribution was observed when the photon energy was located between the K and L edges. This is because the Xe 1s hole state mainly undergoes ultrafast relaxation to the 2p hole state owing to the strong dipole transition moment between the 1s and 2p states.

Background and Blended Spectral Line Reduction in Precision Spectroscopy of EUV and X-ray Transitions in Highly Charged Ions

Extreme ultraviolet spectra of Na-like and Mg-like Os and Ir were recorded at the National Institute of Standards and Technology using a grazing incidence spectrometer. We report a method in EBIT spectral analysis that reduces signals from contaminant lines of known or unknown origin. We utilize similar ion charge distributions of heavy highly charged ions that create similar potentials for lighter contaminating background elements. First-order approximations to ion distributions are presented to demonstrate differences between impurity elements with and without heavy ions present.

Streamer dynamics and periodical discharge regime transitions under repetitive nanosecond pulses with airflow

Although the nanosecond repetitively pulsed (NRP) discharge normally stabilizes into one of three regimes (corona/glow/spark) in a pulse train, another nonintuitive instability recently proved that it could periodically swing between corona and spark regimes characterized by repeated spark quenches and reestablishments (Zhao et al 2022 Plasma Sources Sci. Technol. 31 045005). In this paper, we have further investigated the suitability of NRP discharge regime transitions for different pulsed power supplies and revealed dramatic effects of the gas flow on streamer dynamics that possibly lead to spark quenches. Pulse-sequence and temporally resolved electrical and optical diagnostics were implemented to capture discharge evolutions in long pulse trains. Periodical discharge regime transitions under long-term repetitive nanosecond pulses are prevalent under a transmission line transformer pulser and a commercially available FID pulser with parameter constraints. A minimum deposited energy per spark is required for the successive spark pattern. The spark channel before its quench statistically prefers to deviate upstream rather than following the straight axis or intuitively bending downstream to search for more remnants. Before spark quenches, the initial streamer already either exhibits a large radial ‘detour’ or propagates with a zig-zag profile along the periphery of previous spark regions. The periodical discharge regime transition and effects of the gas flow are qualitatively explained based on the plasma–source coupling, evolutions of dominant negative ion composition, and 3D streamer simulation. Periodical NRP spark quenches are probably initiated with the streamer ‘detour’ and then accelerated by the thermal-ionization feedback instability. Inhomogeneous residual charge distribution and accumulations of complex negative ions with high electron bound energies may facilitate the following discharge to search for the gas inlet. In-depth understanding of NRP discharge instabilities could be reached, which are fundamentally governed by residual charge transport and energy relaxation.

Device Physics, Modeling and Simulation of Organic Electrochemical Transistors

In this work, we investigate organic electrochemical transistors (OECTs) as a novel artificial electronic device for the realization of synaptic behavior, bioelectronics, and a variety of applications. A numerical method considering the Poisson-Boltzmann statistics is introduced to reproduce associated charge densities, electrostatics and switching properties of OECTs. We shed light on the working principle of OECTs by taking into account the ionic charge distribution in the electrolyte and incomplete ionization of the organic semiconductor describing the underlying electrochemical redox reaction. This enables analyzing the OECTs electrical performance as well as a simplified chemical properties via an electrical double layer, doping and de-doping of the OMIEC layer. We have fabricated, characterized, simulated and analyzed OECTs based on PEDOT:PSS, and we show that the proposed model reveals important properties of the device’s working mechanism. The model shows a good agreement with the experimental data of the fabricated devices.

Crystallization in single- and multicomponent neutron star crusts

We use Molecular Dynamics simulations to study the formation and stability of single and multicomponent lattices in the outer crust of Neutron Stars. Including an improved treatment for Gaussian charge distributions of ions we obtain the expressions for the potential and forces arising from electron screened Coulomb interactions using the efficient Ewald sum procedure. %in the plasma. Our findings show that for baryon densities in the outer crust a point-like ion treatment can not fully describe the crystallization behaviour thus the Coulomb parameter, $\Gamma_C$, along with the usual screening parameter, $\kappa$, due to charge neutralizing electron polarizable background, must be complemented with an additional parameter, $\eta$, providing information on the finite size of ions. In our approach we find that including beyond point-like approaches in screened plasmas has a robust impact on calculated lattice energetic stability decreasing crystallization energies per baryon up to $\sim 40\%$ with respect to point-like interaction and, as a consequence, melting point resulting displaced to lower temperatures.

Ionic Transport and Charge Distribution in Miniaturized Electrochemical Energy Storage Devices by Modeling Investigation

Ions are at the core of the mechanism involved in electrochemical energy storage. However, it remains difficult to physically measure the local ionic transport inside working devices. Limiting factors in the local transport in Miniaturized Electrochemical Energy Storage (MEES), especially in 3D Li-ion microbatteries, are investigated using finite element modeling with COMSOL Multiphysics®. This work aims to lay the basements for establishing a relationship between the main limiting factors of Li-ion microbatteries, to provide the critical points for designing the efficient microstructures. Contrary to what was reported in the literature, we demonstrate that the electronic conductivity of the electrodes does not play such a significant role in limiting the performance of a Li-ion microbattery. We show that the main limiting factor is the ionic diffusion inside the electrode, and also the geometry and charge applied to the battery (Crate) which are closely related to ionic diffusion in the electrode.

Toward Understanding the Short‐Circuit Current Loss in Perovskite Solar Cells with 2D Passivation Layers

Herein, a strong short‐circuit current density (JSC) loss is observed when using phenetylammonium iodide (PEAI) as n‐side passivation in p–i–n perovskite solar cells. Comparing experiments with drift–diffusion simulations, different hypotheses for the origin of the JSC loss are presented and evaluated. Whereas the optical properties of the investigated cell stack remain unchanged, the internal quantum efficiency of the PEAI‐based devices decreases drastically. Strong bulk doping and interface traps are ruled out as the origin of the charge extraction limitation. High‐spatial resolution photoluminescence (PL) spectroscopy directly images the inhomogeneity of the PEAI‐based quasi‐2D perovskite wide‐bandgap interlayer, which is found to be crucial for the observed JSC loss. A 2D drift–diffusion model implemented with mobile ions and an inhomogeneous electron transport layer reproduces the experimental behavior accurately. The ionic space charge distribution under short circuit reduces the effective charge‐carrier diffusion length, hindering charge transport toward those domains in the perovskite–electron transport layer interface where electrons can be extracted efficiently. A longer charge‐carrier lifetime reduces the JSC loss, highlighting the importance of suppressed non‐radiative bulk recombination, not only for achieving high open‐circuit voltages, but also for efficient charge extraction.

Formation of Coronal Mass Ejection and Posteruption Flow of Solar Wind on 2010 August 18 Event

The state of the space environment plays a significant role in the forecasting of geomagnetic storms produced by disturbances of the solar wind (SW). Coronal mass ejections (CMEs) passing through the heliosphere often have a prolonged (up to several days) trail with declining speed, which affects propagation of the subsequent SW streams. We studied the CME and posteruption plasma flows behind the CME rear in the event on 2010 August 18 that was observed in quadrature by several space-based instruments. Observations of the eruption in the corona with EUV telescopes and coronagraphs revealed several discrete outflows followed by a continuous structureless posteruption stream. The interplanetary coronal mass ejection (ICME) associated with this CME was registered by the Plasma and Suprathermal Ion Composition instrument aboard the Solar Terrestrial Relations Observatory between August 20, 16:14 UT and August 21, 13:14 UT, after which the SW disturbance was present over 3 days. Kinematic consideration with the use of the gravitational and drag-based models has shown that the discrete plasma flows can be associated with the ICME, whereas the posteruption outflow arrived in the declining part of the SW transient. We simulated the Fe ion charge distributions of the ICME and post-CME parts of the SW using the plasma temperature and density in the ejection region derived from the differential emission measure analysis. The results demonstrate that in the studied event, the post-ICME trailing region was associated with the posteruption flow from the corona rather than with the ambient SW entrained by the CME.

An isogeometric scaled boundary plate formulation for the analysis of ionic electroactive paper

In recent years, electroactive paper emerged as a new alternative in the field of smart actuators. It is based on a cellulose material which is able to bend under the influence of an external electric field similarly as ionic polymer metal composites. The bending mechanism is mainly attributed to the migration of ionic charges over the thickness of a thin sheet of paper. The present contribution proposes a numerical framework for the simulation of electroactive paper. It is based on a scaled boundary plate formulation for isogeometric analysis. In contrast to the standard scaled boundary plate approach, the scaling direction is solved numerically by a B-Spline approximation. This allows to render nonlinear effects over the plate thickness as well as displacement fields of higher continuity. The model is applicable to very thin structures such as electroactive paper, and it also captures the nonlinear ionic charge distribution which is coupled to the bending mechanism of the actuator.

.Solid solutions of redox-isomeric bis-o-semiquinonato cobalt complex with zinc, nickel and manganese compounds having the same composition

Bis-o-semiquinonato cobalt complex (2,2′-bpy)Co(3,6-DBSQ)2 (1) is known to be redox-isomeric (valence tautomeric), i. e. undergo reversible ligand–metal electron transfer accompanied with spin crossover of metal ion under external excitation (2,2′-bpy – 2,2′-bipyridine; 3,6-DBSQ – 3,6-di-tert-butyl-o-benzosemiquinone). The using of one pot reaction allowed us to obtain the number of solid solutions of cobalt complex 1 with similar complexes (2,2′-bpy)M(dioxolene)2 of M = zinc (2), M = nickel (3) and M = manganese (4) in the ratios 1:1 and 1:5 (dioxolene = redox forms of 3,6-di-tert-butyl-o-benzosemiquinone). Composition of solid solutions was established by X-ray spectral microanalysis and confirmed by magnetic measurements. The metals ratio taken into reaction is well reproduced in solid solution. Crystal structures of solid solutions were established by single crystal X-ray diffraction study. X-ray diffraction pattern allows to observe the superpositions of two structures. Variable temperature magnetic susceptibility measurements show that magnetizations of solid solutions are additive and are composed of magnetizations of both complexes. Redox-isomeric transformation occurs in all solid solutions independently of their compositions. The dilution of redox-isomeric compound 1 by inert components 2 and 3 (with zinc and nickel complexes) results in diminishing of transition temperature whereas the dilution by manganese compound does not affect the transition temperature. The reason of this result is proposed to be the maximal difference in molecules volumes (which is determined by ionic radii and charge distributions between metal and ligands) in cobalt/zinc and cobalt/nickel pairs being compared to cobalt/manganese one.

Simultaneous Observation of Tungsten Spectra of W0 to W46+ Ions in Visible, VUV and EUV Wavelength Ranges in the Large Helical Device

Spectroscopic studies for emissions released from tungsten ions have been conducted in the Large Helical Device (LHD) for contribution to the tungsten transport study in tungsten divertor fusion devices and for expansion of the experimental database of tungsten line emissions. Tungsten ions are distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal wire enclosed by a carbon tube. Line emissions from W0, W5+, W6+, W24+–W28+, W37+, W38+, and W41+–W46+ are observed simultaneously in the visible (3200–3550 Å), vacuum ultraviolet (250–1050 Å), and extreme ultraviolet (5–300 Å) wavelength ranges and the wavelengths are summarized. Temporal evolutions of line emissions from these charge states are compared for comprehensive understanding of tungsten impurity behavior in a single discharge. The charge distribution of tungsten ions strongly depends on the electron temperature. Measurements of emissions from W10+ to W20+ are still insufficient, which is addressed as a future task.

Empirical method evaluation of charge – Changing cross sections

A method based on experimental data, theoretical models, and the empirical estimation of experimental parameters in the equilibrium charge distribution of ions is proposed to evaluate charge changing cross sections. This method makes it possible to obtain cross sections for loss and capture of one or several electrons in gaseous and solid targets with the inclusion of the influence of excited states of ions and target atoms.

LDHs-based 3D modular foam with double metal-fluorine interaction for efficiently promoting peroxymonosulfate activation in water pollutant control

Sulfate radical (SO4·-)-based AOPs has gradually become an attractive Fenton-like reaction protocol for refractory wastewater treatment. However, powder form of catalysts is not industrially favorable due to processing issues and challenges in transportation. Design efficient and stable modular catalysts is a promising alternative with application prospect. Here, a series of LDHs 3D porous foam as catalytic module with double metal-F interaction has been constructed by in-situ growth of CoFe-LDH nanoarrays on PVDF framework (CoFeLDH(F)/PVDF) through NH4F-assist hydrothermal, and used for activating PMS in water pollutant control. The high density CoFe-LDH nanoneedles and porous structure endow the catalytic foams with a number of accessible active sites, meanwhile the superhydrophilicity accelerates mass transfer. Moreover, metal-fluorine coordination can provide growth sites and modulate the charge distribution of metal ions, while metal-fluorine ionic bond makes more Co sites exposure. Consequently, the CoFeLDH(F)/PVDF foam displays ultrafast decolorization in flowing dye wastewater. A packed column module is also designed as proof-of-concept device for continuous degradation of simulated dyes polluted river water. This work provides a facile strategy for large-scale pre-treatment of high chroma wastewater in high-salinity, turbulent, and corrosive conditions.