Potential Drop Research Articles

A Self‐Consistent Model of Radial Transport in the Magnetodisks of Gas Giants Including Interhemispheric Asymmetries

AbstractOutward transport of plasma in the inner and middle magnetospheres of gas giants results from an interplay between mass loading from the inner dominant mass sources (volcanic moons), flux tube interchange in the centrifugally unstable magnetospheric plasma disk, turbulent heating of the plasma, and coupling between the equatorial plasma and the planetary upper atmosphere through magnetic field‐aligned current loops and/or Alfvén waves. We present a new analytical formalism describing large scale transport in gas giant systems, combining two historical approaches: radial diffusion of mass and energy through flux tube interchange, and angular momentum transport through corotation enforcement. Under the hypotheses of axisymmetry, steady‐state, and multi‐fluid plasma, we provide transport equations for total contents of flux tubes. They feature new transport parameters accounting for the latitudinal extent of the disk, and self‐consistently include field‐aligned potential drops in the magnetosphere‐ionosphere coupling. Our general formalism has a wealth of applications, two of which are presented, corresponding to the cases of the two gas giants: the effect of interhemispheric asymmetries in the resistive and magnetic properties between the northern and southern ionospheres on the transport of angular momentum at Jupiter, and the influence of the plasma disk thickness on transport at Saturn. We apply our formalism to derive ionospheric parameters and reproduce the Juno and Cassini data. Further work will allow for more complete numerical solutions of our equations, with the aim of capturing the broad complexity of fast rotating magnetospheric systems which can be found inside and outside the Solar System.

An efficient method for electro-thermo-mechanical coupling effect in electrical contact on rough surfaces

In this study, a numerical strategy based on the boundary element method (BEM) is developed to simulate the electrical contact behavior on rough surfaces. By using the Fourier transform, the solutions of the electric potential, temperature rise, and displacement fields in the Fourier space are derived with finite boundaries, in which the electro-thermo-mechanical coupling effect is considered. With the consideration of the contact condition, an iterative algorithm is proposed to seek the solutions of rough surface electrical contact under a given contact force and total electric potential drop. The contact pressure, real contact area, electrical contact resistance, electric current, and temperature rise distribution are predicted. For the validation, the electrical contact results of a spherical punch-half space contact and a rough surface-elastic substrate contact are calculated based on the finite element method. The good agreement between the results from the BEM-based method and the finite element method indicates the accuracy of the presented method. Then, the effect of the total electric potential and the thermal expansion on the electrical contact behavior, the relationship between the contact conductance and contact stiffness, and the probability density function of the contact pressure and temperature rise distributions are evaluated using the proposed method.

Synthesis of 3D rice-like BiOCl battery-type electrode material and evaluation of their electrochemical performance in a symmetrical supercapacitor device configuration

3D porous rice-like BiOCl nanostructure was prepared via solvothermal technique with sodium chlorate as a surfactant which serves as electrode material for the supercapacitor applications. The prepared nanoparticles supported on nickel foam textile exhibit high battery-type charge storage ability in a 3 M KOH aqueous electrolyte solution. The dominance of the battery-type charge storage mechanism of the BiOCl electrode was confirmed through the CV study. Furthermore, the GCD study revealed a good specific capacity of 501 C/g at 0.5 A/g current density and cycle stability of 80% over 2500 cycles. In the presence of a 3 M KOH electrolyte, a symmetric supercapacitor device was constructed with two identical 3D rice-like BiOCl electrodes. This configuration unveiled an impressive energy density of 21.8 Wh/kg at 772.5 W/kg power density. To illustrate its practical viability, two BiOCl/BiOCl symmetric devices were connected in series, successfully powering a red LED for approximately 50 s with high light intensity. This underscores the practical potential of the 3D rice-like BiOCl electrode in energy storage systems. In order to maximize the potential of BiOCl material in the future, the focus could be shifted towards mitigating the challenge of potential drop. This hurdle could be tackled by fabricating nanocomposites of BiOCl incorporated with conductive polymers and graphene oxide, thus elevating its overall performance.

Magnetic field-assisted water splitting at ternary NiCoFe magnetic Nanocatalysts: Optimization study

This study addresses the enhanced splitting of water into H2 and O2 assisted with applied magnetic field at ternary NiCoFe catalyst. The catalyst's activity towards water electrolysis is enhanced in the presence of AC-induced magnetic field (B = 720 μT) and approaches the performance of Pt/C∥IrO2. That is the overpotential at a current density of 10 mA cm−2 (η10) is reduced by 90 mV and 210 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Besides, a significant reduction in the cell voltage of 0.3 V and a power saving of 215.6 kWh during the production of one kg of H2 are obtained when AC magnetic field of 720 μT is applied. A markedly high stability of the catalyst is obtained under magnetic field during a prolonged electrolysis. The magnetohydrodynamic effect is believed to drive water electrolysis at NiCoFe film by reducing the ohmic potential drop across the electrode/solution interface, and increases the rate of charge transfer at the catalyst surface. The results are explained by capacitance measurements revealing maximum capacitance of NiFeCo catalyst in the presence of AC magnetic flux of 720 μT. Thus, favourable adsorption conditions lead to accelerated kinetics of OER and HER.

Estimation of Some Parameters in the Point Defect Model (PDM) for the Passivity of Metals

In this paper, we justify that the potential drop at the barrier layer/solution (bl/s) interface of the barrier layer of the passive film on a metal, φf/s, is a linear function of the applied voltage V and pH in the case of sufficiently thin barrier layer. Furthermore, we show that a relationship exists between parameters α (the dependence of φf/s on V) and β (the dependence of φf/s on pH), that is, those parameters are not independent, in the general case. It is also shown that some dependence of parameters α and β on temperature can exist. However, this dependence in the practical region (0 °C–100 °C) is weak and, in many cases, it is possible to neglect the dependence of parameters α and β on temperature. Finally, we show that it is possible to estimate, theoretically, the parameter β (and accordingly parameter α) by using models for specific systems. For the system considered in the current report (carbon steel in concrete pore water), the estimated value of parameter β is confirmed experimentally. These findings are discussed in terms of the electronic and point defect structures of the barrier layer.

Advanced hemodynamics for prognostication in heart failure: the pursuit of the patient-specific tipping point.

Objective tools to define the optimal time for referral for advanced therapies and to help guide escalation and de-escalation of support can improve management decisions and outcomes for patients with advanced heart failure. The current parameters have variable prognostic potential depending on the patient population being studied and often have arbitrary thresholds. Here, a mathematical and physiological framework to define the patient-specific tipping point of myocardial energetics is defined. A novel hemodynamic parameter known as the myocardial performance score (MPS), a marker of power and efficiency, is introduced that allows for the objective assessment of the physiological tipping point. The performance of the MPS and other advanced hemodynamic parameters including aortic pulsatility index (API) and cardiac power output (CPO) in predicting myocardial energetics and the overall myocardial performance was evaluated using a validated computer simulation model of heart failure (Harvi) as well as a proof-of-concept clinical validation using a cohort of the Society for Cardiovascular Angiography and Interventions (SCAI) Stage C cardiogenic shock patients. Approximately 1010 discrete heart failure scenarios were modeled. API strongly correlated with the left ventricular coupling ratio (R2 = 0.81) and the strength of association became even stronger under loaded conditions where pulmonary capillary wedge pressure (PCWP) was >20 mmHg (R2 = 0.94). Under loaded conditions, there is a strong logarithmic relationship between MPS and mechanical efficiency (R2 = 0.93) with a precipitous rise in potential energy (PE) and drop in mechanical efficiency with an MPS <0.5. An MPS <0.5 was able to predict a CPO <0.6 W and coupling ratio of <0.7 with sensitivity (Sn) of 87%, specificity (Sp) of 91%, positive predictive value of 81%, and negative predictive value of 94%. In a cohort of 224 patients with SCAI Stage C shock requiring milrinone initiation, a baseline MPS score of <0.5 was associated with a 35% event rate of the composite endpoint of death, left ventricular assist device, or transplant at 30 days compared with 3% for those with an MPS >1 (p < 0.001). Patients who were able to augment their MPS to >1 after milrinone infusion had a lower event rate than those with insufficient reserve (40% vs. 16%, p = 0.01). The MPS, which defines the patient-specific power-to-efficiency ratio and is inversely proportional to PE, represents an objective assessment of the myocardial energetic state of a patient and can be used to define the physiological tipping point for patients with advanced heart failure.

Design of liposomal nanocarriers with a potential for combined dexamethasone and bevacizumab delivery to the eye

Clinicians face numerous challenges when delivering medications to the eyes topically because of physiological barriers, that can inhibit the complete dose from getting to the intended location. Due to their small size, the ability to deliver drugs of different polarities simultaneously, and their biocompatibility, liposomes hold great promise for ocular drug delivery. This study aimed to develop and characterise a dual loaded liposome formulation encapsulating Bevacizumab (BEV) and Dexamethasone (DEX) that possessed the physicochemical attributes suitable for topical ocular delivery. Liposomes were prepared by using thin film hydration followed by extrusion, and the formulations were optimised using a design of experiments approach. Physicochemical characterisation along with cytocompatibility and bioactivity of the formulations were assessed. Liposomes were successfully prepared with a particle size of 139 ± 2 nm, PDI 0.03 ± 0.01 and zeta potential −2 ± 0.7 mV for the optimised formulation. BEV and DEX were successfully encapsulated into the liposomes with an encapsulation efficiency of 97 ± 0.5 % and 26 ± 0.5 %, respectively. A sustained release of BEV was observed from the liposomes and the bioactivity of the formulation was confirmed using a wound healing assay. In summary, a potential topical eye drop drug delivery system, which can co-load DEX and BEV was developed and characterised for its potential to be used in ocular drug delivery.

Loss cone effects and monotonic sheath conditions of a partially magnetized plasma sheath

In this Letter, we propose the conditions for monotonic plasma sheaths adjacent to a floating wall in the presence of an applied, oblique magnetic field. The electron velocity distribution function (VDF) at the sheath edge obtained from a kinetic model exhibits a loss cone shaped truncation. Using an approximation of the truncated VDF, we derive an analytical framework of the sheath edge condition (i.e., Bohm condition), namely, the relation of ion injection velocity and sheath potential drop as a function of the magnetic field angle. The results show that the sheath edge velocity and total potential drop decrease for a steady-state sheath, which eventually collapses when the magnetic field lines become parallel to the wall.

Interfacial Electronic States of GeC/g-C3N4 van der Waal Heterostructure with Promising Photocatalytic Activity via Hydrogenation.

The bandgap of most known two-dimensional materials can be tuned by hydrogenation, although certain 2D materials lack a sufficient wide bandgap. Currently, it would be perfect to design non-toxic, low-cost, and high-performance photocatalysts for photocatalytic water splitting via hydrogenation. We systematically examine the impact of hydrogenation on the optical and electronic characteristics of GeC/g-C3N4 vdW heterostructures (vdWHs) with four different stacking patterns using first-principles calculations. The phonon spectra, interlayer distance, binding energies and ab initio molecular dynamics calculations show the kinetic, mechanical, and thermal stability of GeC/g-C3N4 vdWH after hydrogenation at 300, 500 and 800 K and possesses anisotropic Poisson's ratio, Young's and bulk modulus, suggesting that it's a promising candidate for experimental fabrication. According to an investigation of its electronic properties, GeC/g-C3N4 vdWH has a bandgap of 1.28 eV, but hydrogenation dramatically increases it to 2.47 eV. As a result of interface-induced electronic doping, the electronic states in g-C3N4 might be significantly adjusted by coming into contact with hydrogenated GeC sheets. The vdWH exhibits a type-II semiconductor, which can enhance the spatial separation of electron-hole pairs and has a strong red-shift of absorption coefficient than those of the constituent monolayers. The high potential drop caused by the significant valence and conduction band offsets effectively separated the charge carriers. The absorption coefficient of GeCH2/g-C3N4 vdWH is highly influenced by a biaxial compressive strain more than the biaxial tensile strain. Our theoretical research implies that the hydrogenated GeCH2/g-C3N4 vdWH possesses tunable optical and electronic behaviour for use as a hole-transport material in solar energy harvesting, nanoelectronic and optoelectronic devices.

New approaches to dissect leaf hydraulics reveal large gradients in living tissues of tomato leaves.

The water status of the living tissue in leaves is critical in determining plant function and global exchange of water and CO2. Despite significant advances in the past two decades, persistent questions remain about the tissue-specific origins of leaf hydraulic properties and their dependence on water status. We use a fluorescent nanoparticle reporter that provides water potential in the mesophyll apoplast adjacent to the epidermis of intact leaves to complement existing methods based on the Scholander Pressure Chamber (SPC). Working in tomato leaves, this approach provides access to the hydraulic conductance of the whole leaf, xylem, and outside-xylem tissues. These measurements show that, as stem water potential decreases, the water potential in the mesophyll apoplast can drop below that assessed with the SPC and can fall significantly below the turgor loss point of the leaf. We find that this drop in potential, dominated by the large loss (10-fold) of hydraulic conductance of the outside-xylem tissue, is not however strong enough to significantly limit transpiration. These observations highlight the need to reassess models of water transfer through the outside-xylem tissues, the potential importance of this tissue in regulating transpiration, and the power of new approaches for probing leaf hydraulics.

Unraveling the evolution of Cathode–Solid electrolyte interface using operando X-ray Photoelectron spectroscopy

Understanding the evolution of the solid electrolyte-electrode interface is currently one of the most challenging obstacles in the development of solid-state batteries (SSBs). Here, we develop an X-ray Photoelectron Spectroscopy (XPS) that allows for operando measurement during cycling. Based on theoretical analysis and the modulated electrode and detector co-grounding mode, the displacement of binding energy can be correlated with the surface electrostatic potential of the material, revealing the charge distribution and composition evolution of the space charge layer between the cathode and the electrolyte. In the investigation of typical LiCoO2 (LCO)/Li6PS5Cl (LPSC)/Li–In batteries, we observed the static potential difference and oxidative decomposition between LPSC and LCO, and the effectiveness of the LiNbO3 coating in reducing potential difference and inhibiting the diffusion of Co and oxidation of S species. Furthermore, our study also revealed that the potential drop between LiNi0·8Co0·1Mn0·1O2 and LPSC is smaller than that of LCO, whilst that between Li3InCl6 and LCO remains near zero. The proposed operando XPS method offers a novel approach for real-time monitoring of interface potential and species formation, providing rational guidance for the interface engineering in SSBs.

The Effect of Bulk Modification of the MF-4SK Membrane with Phosphorylated Hyper-Branched Dendrimer Bolthorn H20 on the Mechanisms of Electroconvection/Dissociation of Water and Specific Selectivity to Divalent Ions

This study focuses on the modification of ion-exchange membranes by incorporating a phosphorylated dendrimer into sulfonated polytetrafluoroethylene membranes to enhance the specific selectivity between mono-/divalent ions, using the Ca2+/Na+ pair as an example. This research employs mechanical, physicochemical, and electrochemical analyses to explore the effects of P-H20 incorporation on membrane properties. Bulk modification significantly increases membrane selectivity towards calcium ions (the specific permselectivity coefficient rises from 1.5 to 7.2), while maintaining the same level of the limiting current density. Other findings indicate that bulk modification significantly changes the transport-channel structure of the membrane and alters the mechanism of over-limiting mass transfer. The over-limiting current for the pristine membrane is mainly due to non-equilibrium electroconvection, while modified membranes actively participate in the water-splitting reaction, leading to the suppression of the electroconvection. Despite this drawback, the decrease of the over-limiting potential drop results in a decrease in specific energy consumption from 0.11 to 0.07 kWh/mol. In the underlimiting current mode, the specific energy consumption for all studied membranes remains within the same limits of 0.02–0.03 kWh/mol.

Electrically driven proton transfer promotes Brønsted acid catalysis by orders of magnitude.

Electric fields play a key role in enzymatic catalysis and can enhance reaction rates by 100,000-fold, but the same rate enhancements have yet to be achieved in thermochemical heterogeneous catalysis. In this work, we probe the influence of catalyst potential and interfacial electric fields on heterogeneous Brønsted acid catalysis. We observed that variations in applied potential of ~380 mV led to a 100,000-fold rate enhancement for 1-methylcyclopentanol dehydration, which was catalyzed by carbon-supported phosphotungstic acid. Mechanistic studies support a model in which the interfacial electrostatic potential drop drives quasi-equilibrated proton transfer to the adsorbed substrate prior to rate-limiting C-O bond cleavage. Large increases in rate with potential were also observed for the same reaction catalyzed by Ti/TiOyHx and for the Friedel Crafts acylation of anisole with acetic anhydride by carbon-supported phosphotungstic acid.

Development of Aqueous Organic Flow Battery Using SPEEK Membrane and Eco-Friendly Electrolytes

Aqueous organic redox flow batteries (AORFBs) are a type of flow battery that offers a promising solution for energy storage, and one of the main issues is selecting low-cost membranes with high ion conductivity to enhance performance and efficiency. In this study, low-cost sulfonated poly ether ether ketone (SPEEK) membranes were fabricated using the casting method, with the polymer/solvent ratios of SPEEK and N,N'-dimethylformamide (DMF) being varied. The Nafion 117 membrane was used as a benchmark for comparison. The performance of aqueous organic redox flow batteries employing anthraquinone-2-sulfonic acid (AQS) and 1,2-benzoquinone-3,5-disulfonic acid (BQDS) as electrolytes was evaluated. The SPEEK membranes were determined to have dense, homogeneous surfaces with no flaws and a thickness of 60 microns. In addition, their physicochemical properties, such as water uptake, swelling ratio, ion exchange capacity, and degree of sulfonation, were investigated. The results showed that the SPEEK membranes had better rate performance and cycle stability when compared to the Nafion117 membrane during charge-discharge cycles. Additionally, the SPEEK membranes exhibited slower potential drops and higher power density during constant current mode operation, despite showing no significant differences in energy efficiency and power density. These findings demonstrate the potential of SPEEK membranes for use in AORFBs and as a benchmark for future research and development.

One-dimensional multi-fluid model of the plasma wall transition

A one-dimensional multi-fluid model of the plasma wall transition is presented. The plasma is composed of singly charged positive ions, electrons and negative ions. Positive ions are assumed to obey the continuity, momentum transfer and energy transport equation, while the electrons and negative ions are treated by the continuity and momentum transfer equation. For the positive ions the closure is done by assuming that heat flux in the plasma is zero, while both negative species are treated as isothermal, with the pressure gradient term being proportional to the density gradient. The potential drop in the pre-sheath can be determined either by the electrons or the negative ions – depending on their densities in the unperturbed plasma. It is shown how the boundary density of both particle species can be in some cases determined very precisely.

Localized Hybrid Simulation of Martian Crustal Magnetic Cusp Regions: Vertical Electric Potential Drop and Plasma Dynamics

AbstractThe localized crustal magnetic fields of Mars play an important role in the planet’s ionosphere‐solar wind interaction. Various physical processes in the induced magnetosphere, such as particle precipitation, field‐aligned currents, and ion outflow, are usually associated with the crustal magnetic cusp regions, where field lines are mostly vertical and open to space. Due to the small spatial scale (a few hundred km) of the Martian crustal magnetic cusps, localized models with high spatial resolutions and ion kinetics are needed to understand the physical processes. We adapt the simulation platform HYB developed at the Finnish Meteorological Institute to a moderately strong magnetic cusp above the Martian exobase with a 2‐D simulation domain assuming periodic boundary conditions on the third dimension. Two plasma sources are included in the simulation: hot protons from the induced magnetosphere and cold heavy ions (O+) from the ionosphere. Our model results can qualitatively reproduce the vertical electric potential drop, particle transport, and field aligned current in the cusp region. The vertical electric potential is built up mostly by the Hall electric field as a result of the separation between ion and electron fluxes of the downward plasma flow. By varying the model inputs, we found that the vertical potential drop depends on ionospheric ion density and magnetic field strength. These results tell us that energy is transferred from magnetospheric plasma to ionospheric plasma through the vertical electric potential buildup in magnetic cusps and how this process may affect electron precipitation, ion escape, and ionosphere conditions at Mars.

Ultrathin Zincophilic Interphase Regulated Electric Double Layer Enabling Highly Stable Aqueous Zinc-Ion Batteries

HighlightsElectric double-layer regulation enabled by an ultrathin multifunctional solid electrolyte interphase layer with zincophilicity and rapid transport kinetics.Lowered potential drop over the Helmholtz layer and suppressed diffuse layer.Inhibited side reactions and uniform zinc deposition.

The Implication of Different Transmission Protocols for Vehicular Networks using NS-2

A vehicular network, categorized as an ad-hoc network, operates without fixed base station infrastructure or centralized management. In this setup, each network entity can serve as a router or a host, facilitating communication via multiple links. Unlike a mobile ad-hoc network, a vehicular network allows nodes to freely join or leave the network. For data transmission, various network layers are involved in delivering packets, with TCP and UDP protocols commonly employed. However, prior research has highlighted the limitations of Vehicular Ad-Hoc Networks (VANETs), particularly due to the surge in vehicular numbers on roads. This situation can trigger issues such as network congestion, leading to increased packet delivery delays and potential packet drops, ultimately compromising network performance. Moreover, when vehicles travel at high speeds on highways, quick message transmission is crucial, often without waiting for acknowledgments from both the transmitter and receiver. To address these challenges, some of the benefits of the User Datagram Protocol (UDP) can be integrated into vehicular network technologies. Consequently, this study aims to assess the data transfer performance between Transmission Control Protocol (TCP) and UDP, focusing on metrics like packet delivery ratio, packet loss, and packet drop, while varying vehicle density. The research location was Persiaran Permai, Seksyen 7, Shah Alam, Malaysia, and simulation was conducted using tools such as JOSM, MOVE, and NS-2. The findings reveal noteworthy differences: TCP exhibits a superior average packet delivery ratio (99.44% vs. 83.56%) and lower packet loss (0.56% vs. 16.45%) compared to UDP. Conversely, UDP demonstrates better performance in terms of average packet drop (0 compared to 6.75) when compared to TCP.

Stress Corrosion Cracking of High-Strength Ni-Base Alloys in Pressurized Water Reactor Primary Water Containing KOH vs. LiOH

The stress corrosion cracking (SCC) behavior of high-strength Ni-base Alloys X-750 and 718 has been investigated to assess the effect of replacing LiOH with KOH as the pH moderator in pressurized water reactor (PWR) primary circuit coolant. The SCC initiation behavior of X-750 was evaluated by multitensile specimen constant load test in either LiOH- or KOH-containing PWR primary water. The SCC growth behavior of X-750 and Alloy 718 was evaluated on compact tension specimens with on-the-fly changes between LiOH- and KOH-containing water in three different PWR primary water chemistries. Direct current potential drop technique was used for in situ monitoring of crack initiation time and crack extension in SCC initiation and propagation tests, respectively. The results suggest no significant effect of KOH vs. LiOH on the SCC initiation or propagation of the tested materials.

In Situ Spectroscopic Elucidation of the Electrochemical Potential Drop at Polyelectrolytes/Au Interfaces.

Polyelectrolytes have been widely applied in electrochemical devices. Understanding the polyelectrolyte/electrode interfaces is pivotal for polyelectrolyte-based applications. Here, we measured the electrochemical potential drop and the local activity of the mobile ion of H+ or OH- at the polyelectrolytes/Au interfaces by in situ electrochemical surface-enhanced Raman spectroscopy and voltammetry in three-electrode cells. We found that the potential dependences of the electrochemical potential drop in polyelectrolytes were smaller than that in conventional electrolyte solutions. The interfacial activity of H+ or OH- was much lower than that of bulk polyelectrolytes. The potential-dependent molecular dynamics simulations showed that the mobility of ionomers of polyelectrolytes in an electrostatic field was limited by a polymer matrix. These results suggested a characteristically thicker compact layer in the electrical double layer of a polyelectrolyte/electrode interface due to the accumulation of mobile H+ or OH- with a thicker hydration layer and immobile ionomers.