Charge Variation Research Articles

Determination of Surface Parameters of Iron(III) Hydroxide Sorbent

The surface layer parameters of iron(III) hydroxide were studied. The surface charge, the sorption of proton H+, hydroxyl OH– as a function of hydration time (TCT), the pH of the suspension solution and the sorbent concentration were presented. For this purpose, two methods were chosen: potentiometric mass titration (PMT) and potentiometric time titration (PTT). The concentrations suspensions used were 20, 40 and 60 g/L. The variations of surface charge with the time contact, Q = f(TCT) were examined for hydration time ranging from zero to 72 h. The isoelectric point (IEP) and point zero charge (PZC) were defined using the variations pH = f(TCT) resulting from protonation/deprotonating of surface sites >S–OH with derivative methods d(pH)/d(TCT) = f(pH) the values of PZC and IEP were found: PZC = 7.45 ± 0.1 and IEP = 7.65 ± 0.1.

Comparative study of methodologies for SOH diagnosis and forecast of LFP and NMC lithium batteries used in electric vehicles

The exponential growth of electric mobility requires alternatives to extend the life of batteries in new applications and reduce the environmental impact of retired lithium batteries. The second life is an economic and environment-friendly alternative for battery management. The development of fast, low-cost, and reliable diagnostic methodologies makes it possible to increase the economic benefits and reduce the remanufacturing time of second-life batteries (SLBs). In the present work, battery state of health (SOH) distribution analysis, incremental capacity (IC), internal resistance (IR), and electrochemical impedance spectroscopy (EIS) were applied as diagnostic methodologies for two different chemistries of lithium-ion batteries previously used in electric vehicles (EV). In addition, module equalization in batteries was done in order to assess whether the state of module charge (SOC) variation affects the SOH. The results demonstrate that the diagnosis methodology depends on the chemistry of the battery, and that there is no single reliable diagnostic procedure that can be applied to all types of lithium-ion batteries. It was determined that the most adequate diagnostic method for LFP batteries (LiFePO4 cathode) is the IC method, while for NMC batteries (LiNi0.33Mn0.33Co0.33O2 cathode) the IR and EIS diagnostic methods are the most appropriate. Similarly, the present work proposed a simple methodology for IC capacity diagnosis and a general expression for SOH determination by IC and incremental voltage diagnosis of LFP batteries. Higher stability of LFP respect to NMC modules was observed during the SLBs performance, retaining >99 % after 500 cycles for LFP, compared with 90.2 % for NMC. The remaining useful life (RUL) shows that there are kinetics and lithium inventory changes in the batteries temperature-dependent.

Robust single modified divacancy color centers in 4H-SiC under resonant excitation

Color centers in silicon carbide (SiC) offer exciting possibilities for quantum information processing. However, the challenge of ionization during optical manipulation leads to charge variations, hampering the efficacy of spin-photon interfaces. Recent research predicted that modified divacancy color centers can stabilize their charge states, resisting photoionization. This study presents a method for precisely creating single divacancy arrays in 4H-SiC using a focused helium ion beam. Photoluminescence tests reveal consistent emission with minimal linewidth fluctuations (∼50 MHz over 3 h). By measuring the ionization rate for different polytypes of divacancies, we found that the modified divacancies are more robust against resonant excitation. Furthermore, angle-resolved photoluminescence excitation spectra unveil two resonant-transition lines with orthogonal polarizations. Enhanced optical and spin characteristics were notably observed in these color centers compared to those generated through carbon-ion and shallow implantation methods, positioning modified divacancies as promising contenders for advancing quantum networking.

Statewide Variation in Practices and Charges for Primary Spontaneous Pneumothorax in Maryland, United States: A Retrospective Study

Statewide Variation in Practices and Charges for Primary Spontaneous Pneumothorax in Maryland, United States: A Retrospective Study

A Microfluidic-Based Sensing Platform for Rapid Quality Control on Target Cells from Bioreactors.

We investigated the design and characterization of a Lab-On-a-Chip (LoC) cell detection system primarily designed to support immunotherapy in cancer treatment. Immunotherapy uses Chimeric Antigen Receptors (CARs) and T Cell Receptors (TCRs) to fight cancer, engineering the response of the immune system. In recent years, it has emerged as a promising strategy for personalized cancer treatment. However, it requires bioreactor-based cell culture expansion and manual quality control (QC) of the modified cells, which is time-consuming, labour-intensive, and prone to errors. The miniaturized LoC device for automated QC demonstrated here is simple, has a low cost, and is reliable. Its final target is to become one of the building blocks of an LoC for immunotherapy, which would take the place of present labs and manual procedures to the benefit of throughput and affordability. The core of the system is a commercial, on-chip-integrated capacitive sensor managed by a microcontroller capable of sensing cells as accurately measured charge variations. The hardware is based on standardized components, which makes it suitable for mass manufacturing. Moreover, unlike in other cell detection solutions, no external AC source is required. The device has been characterized with a cell line model selectively labelled with gold nanoparticles to simulate its future use in bioreactors in which labelling can apply to successfully engineered CAR-T-cells. Experiments were run both in the air-free drop with no microfluidics-and in the channel, where the fluid volume was considerably lower than in the drop. The device showed good sensitivity even with a low number of cells-around 120, compared with the 107 to 108 needed per kilogram of body weight-which is desirable for a good outcome of the expansion process. Since cell detection is needed in several contexts other than immunotherapy, the usefulness of this LoC goes potentially beyond the scope considered here.

Holographic thermodynamics of BTZ black holes and Tsallis entropy

This paper presents a detailed study of the thermodynamics of charged BTZ black holes using the conformal holographic extended thermodynamics formalism and Tsallis statistics. The cornerstone of our thermodynamic framework is the re-scaling of CFT by the conformal factor, which is considered a thermodynamic parameter. Here, the AdS radius is distinct from the CFT radius, allowing for independent variations of the central charge and volume. Our analysis revealed that the thermodynamic behavior of charged BTZ black holes in three dimensions is characterized by the stability and absence of phase transitions, contrasting with the behavior of four-dimensional black holes. The central charge of CFT notably influences the thermal evolution of these black holes, with a smaller central charge leading to faster thermal processes. Additionally, the temperature of large black holes is proportional to their entropy. By incorporating Tsallis statistics into our study, we found that the stability of black holes depends on the Tsallis parameter. Black holes are always stable when the Tsallis parameter is less than 2. However, if this parameter is greater than 2, a first-order phase transition occurs between small stable and large unstable. Overall, our findings contribute to a deeper understanding of the holographic thermodynamics of lower-dimensional black holes and the impact of non-extensive statistics on their physical properties.

Computational Screening of Asymmetric Dual Sites by Bader Charge Variation Facilitates C–C Coupling for CO2 Photoreduction to C2H4

Computational Screening of Asymmetric Dual Sites by Bader Charge Variation Facilitates C–C Coupling for CO₂ Photoreduction to C₂H₄

Topological and site disorder in boron nitride networks.

Amorphous boron nitride (a-BN) is modelled over a wide range of densities using a relatively simple potential model augmented with site charges. The local topology (defined, for example, through the total nearest-neighbour coordination number), appears near-constant across a wide range of densities and site charges. Furthermore,totalscattering andtotalpair distribution functions also show few changes as a function of either density or site charge. Variation of the site charges directly controls the level of site (rather than topological) disorder meaning that although total pair functions may be near-constant, the underlying partial contributions may be very different. Direct contact is made with both experiment and (more recent) density-functional theory-based modelling work.

Charge Modulation at the Liquid Crystal Droplet-Aqueous Interface Enables Ultrasensitive, Nonspecific Protein Detection.

Thermotropic nematic liquid crystals (LC) have been utilized to sense/detect various analytes such as polymers, surfactants, lipids, etc. However, their use for protein detection depends on pre-adsorbed molecules, co-nematogens, or biomolecular agents for specificity.This approach impedes the platform's sensitivity with a detection limit for the folded proteins generally reported in the micromolar concentration range. Here, this work provides fundamental insights into the type of molecular interactions and their modulation that can drive ultrasensitive protein detection at an LC microdroplet/aqueous interface formed without adding an auxiliary co-nematogen. Using ultraviolet (UV) light treated 4-cyano-4'-pentylbiphenyl (5CB) LC and a flow-focused microfluidic device, we prepared different populations of monodisperse and highly negatively charged microdroplets in water. Adding an aqueous solution of various model proteins(α-synuclein, α-chymotrypsin, myoglobin, or bovine serum albumin, BSA) with different secondary structures and surface charges triggers a rapid radial- to bipolar-defect transition in these microdroplets. Isothermal titration calorimetry measurement and molecular dynamic simulation studies attribute this to the dominant electrostatic force-mediated adsorption of proteins at the LC/aqueous interface.Further, bioconjugation-based variation of protein surface charge allows tuning their detection limit.These findings can provide crucial physical cues for designing responsive LC systems and establishing a foundation for developing versatile, molecularly tailored, and highly specific biomolecular detection platforms.

Large eddy simulations of electrification of liquid dielectrics in channel flow

In this paper we present a computational study of electrification of liquid dielectrics in channel flow and at moderate turbulence intensities. For purposes of computational savings this study consists of large eddy simulations, according to which the large turbulent scales are directly resolved by the computational grid while the effect of the smaller unresolved scales is suitably modeled. First we examine different subgrid-scale models for the electric charge density. Their efficacy is then assessed via comparisons with results from direct numerical simulations at low turbulence intensities. According to our comparisons and analysis, the most efficient model is the one based on the eddy diffusivity approach and the introduction of the turbulent electric Schmidt number. Subsequently, we present numerical results of electrification of benzene in channel flow and at different Reynolds numbers. Herein we discuss the various stages of the electrification process and the variation of the total charge and streaming current with the turbulence intensity. According to our findings, the increase of the turbulence intensity rises dramatically not only the amount of charge transported in the bulk of the fluid but also the rate at which this transport takes place. Finally, we present results for the statistics of the charge density, which provide additional insight about the distribution of the electric charges in the liquid.

On Vortices in Viscous Dusty Plasma With a Variable Dust Charge

ABSTRACTA time‐dependent nonlinear model that describes the generation of vortex patterns of dust grains in a magnetized strongly coupled dusty plasma where ions are taken magnetized [Nebbat and Annou, Phys. Plasmas 30 (8), 082108 (2023)] is augmented. The effect of viscosity and dust charge variation on the characteristics of the vortex is investigated.

Investigation of the specific charge variations in determining the optimal methods for drilling and blasting of tunnels

In this research, in order to compare and select the optimum patterns, two parameters of specific charge and specific drilling are used. Two explosive substances, including ammonium nitrate and fuel oil (ANFO) and Amulet, are used to charge the holes located on the cross-section of the tunnels in order to advance by 3 meters. Also, the cross-section of the selected tunnels was 19, 28, 32, 40, 48, 50, 65, and 76 square meters with horseshoe, circle and D-shaped. The diameter of the explosive hole is 48 mm for the Norwegian method and 51 mm for the two energy balance models and the Swedish method to compare them. A total of 160 designs are prepared for three types of limestone, sandstone and marl. The results obtained for two parameters of specific charge and special drilling for the selected rock material are completely opposite. Also, in the Swedish methods, according to the Amulet, the values of the calculated parameters are close to the energy balance model. Finally, according to the geomechanical parameters of the rock, for the Swedish method and the energy balance model in charging with amulet explosives, the energy balance model and the Holemberg-Persson method are proposed in the optimal design for the tunnel drilling and blasting pattern. In addition, for the Norwegian method and the energy balance model in charging the holes with ANFO, the energy balance model is prior to the Norwegian method. The amount of stemming of holes in different parts of the tunnel face is less for the Swedish method than the Norwegian and energy balance models.

Warped CFT duals of the Plebański-Demiański family of solutions

In this paper, we analyze the symmetry properties of the complete family of type D spacetimes generalized form the Plebański-Demiański solution in four dimensions holographically in terms of a warped CFT. The generalized Plebański-Demiański solutions are black hole-like spacetimes characterized by seven physical parameters. Most of the black holes in four dimensions are included within this family. Generically consider a solution with horizon in this family, we figure out the possible warped conformal symmetry attached to the horizon. The horizon can be either extremal or non-extremal. In the extremal case, the near horizon region can be mapped to an infinite spacetime with geometry given by a warped and twist product of AdS2 and S2. The new boundary conditions for AdS2 as well as their higher dimensional uplifts are applied here to manifest the asymptotic symmetry as the warped conformal symmetry. In the non-extremal case, the global warped conformal symmetry is singled out by analyzing the scalar wave equation with constant frequency. The local warped conformal symmetries are represented by the charge algebra associated to the vector fields which preserve the scalar wave equation as well as its frequency. In defining the variation of the covariant charges, a proper counterterm is introduced for consistency conditions which is supposed to be suitable for all the solutions within the family. As a consistency check, the horizon entropy is reproduced by the entropy formula of the warped CFT by using its modular covariance and the central terms derived in the bulk spacetimes.

Experimental study of the performance of a water-to-water heat pump equipped with a liquid receiver with different charge levels

This paper presents an experimental investigation of the effects of a decreasing refrigerant charge on the performance and operating conditions of an R513A water-to-water heat pump equipped with a large liquid receiver, an electronic expansion valve, and a vapor accumulator at the compressor inlet. The mass of the refrigerant inside the machine is progressively extracted to simulate refrigerant leakages occurring during the normal operation or in case of failures. The results show that the subcooling is the parameter mostly affected by a refrigerant charge variation since it rapidly collapses to 0 K with the charge reduction. Furthermore, it is possible to identify three different zones in which almost all the properties analyzed (COP, heating capacity, operating pressures and expansion valve opening) exhibit peculiar trends with the charge decrease: subcooling sensitivity zone, constant parameters zone, and compressor failure risk zone. The extension of these zones is determined by the size of the liquid receiver which is installed in the system and, for the heat pump under consideration, is between 100% and 95% of the initial charge for the first zone, between 95% and 40% for the second zone, and below 40% for the third zone.

Analysis of electroviscous effects in electrolyte liquid flow through a heterogeneously charged uniform microfluidic device

Charge-heterogeneity (i.e., surface charge variation in the axial direction of the device) introduces non-uniformity in flow characteristics in the microfluidic device. Thus, it can be used for controlling practical microfluidic applications, such as mixing, mass, and heat transfer processes. This study has numerically investigated the charge-heterogeneity effects in the electroviscous (EV) flow of symmetric (1:1) electrolyte liquid through a uniform slit microfluidic device. The Poisson’s, Nernst-Planck (N-P), and Navier–Stokes (N-S) equations are numerically solved using the finite element method (FEM) to obtain the flow fields, such as total electrical potential (U), excess charge (n *), induced electric field strength (E x), and pressure (P) fields for following ranges of governing parameters: inverse Debye length (2 ≤ K ≤ 20), surface charge density (4 ≤ S 1 ≤ 16), and surface charge-heterogeneity ratio (0 ≤ S rh ≤ 2). Results have shown that the total potential (∣ΔU∣) and pressure (∣ΔP∣) drop maximally increase by 99.09% (from 0.1413 to 0.2812) (at K = 20, S 1 = 4) and 12.77% (from 5.4132 to 6.1045) (at K = 2, S 1 = 8), respectively with overall charge-heterogeneity (0 ≤ S rh ≤ 2). Electroviscous correction factor (Y, i.e., ratio of effective to physical viscosity) maximally enhances by 12.77% (from 1.2040 to 1.3577) (at K = 2, S 1 = 8), 40.98% (from 1.0026 to 1.4135) (at S 1 = 16, S rh = 1.50), and 41.35% (from 1 to 1.4135) (at K = 2, S rh = 1.50), with the variation of S rh (from 0 to 2), K (from 20 to 2), and S 1 (from 0 to 16), respectively. Further, a simple pseudo-analytical model is developed to estimate the pressure drop in EV flow, accounting for the influence of charge-heterogeneity based on the Poiseuille flow in a uniform channel. This model predicts the pressure drop ± 2%–4% within the numerical results. The robustness and simplicity of this model enable the present numerical results for engineering and design aspects of microfluidic applications.

Strength of London Dispersion Forces in Organic Structure Directing Agent-Zeolite Assemblies.

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)-here tetraalkyl-ammonium or -phosphonium molecules-and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of the structures of OSDAs or FWs, and of variations in charges and thermal motions. All calculations considered-DFT-D3 and BOMD undertaken by us, and molecular mechanics from an accessible database-led to the same trend. The mean energy of these dispersion forces is ca. -2 kcal.mol-1 per H for efficient H-O contacts.

A Minimal PBPK Model Describes the Differential Disposition of Silica Nanoparticles In Vivo.

Nanoparticles (NPs) have emerged as promising candidates for drug delivery due to their tunable physical and chemical properties. Among these, silica nanoparticles (SiNPs) are particularly valued for their biocompatibility and adaptability in applications like drug delivery and medical imaging. However, predicting SiNP biodistribution and clearance remains a significant challenge. To address this, we developed a minimal physiologically-based pharmacokinetic (mPBPK) model to simulate the systemic disposition of SiNPs, calibrated using in vivo PK data from mice. The model assesses how variations in surface charge, size, porosity, and geometry influence SiNP biodistribution across key organs, including the kidneys, lungs, liver, and spleen. A global sensitivity analysis identified the most influential parameters, with the unbound fraction and elimination rate constants for the kidneys and MPS emerging as critical determinants of SiNP clearance. Non-compartmental analysis (NCA) further revealed that aminated SiNPs exhibit high accumulation in the liver, spleen, and kidneys, while mesoporous SiNPs primarily accumulate in the lungs. Rod-shaped SiNPs showed faster clearance compared to spherical NPs. The mPBPK model was extrapolated to predict SiNP behavior in humans, yielding strong predictive accuracy with Pearson correlation coefficients of 0.98 for mice and 0.92 for humans. This model provides a robust framework for predicting the pharmacokinetics of diverse SiNPs, offering valuable insights for optimizing NP-based drug delivery systems and guiding the translation of these therapies from preclinical models to human applications.

Heat-Excitation-Based Triboelectric Charge Promotion Strategy.

The surface charge decay is observed at high temperatures due to thermionic emission, which, however, may not be the only mechanism contributing to the surface charge variation. Here, a triboelectric charge promotion strategy due to the heat-excitation effect of hot electrons near the fermi level is demonstrated, while the final charge is determined by the balance between thermionic emission and the heat-excitation effect. It is demonstrated that metals with lower work function exhibit a better heat excitation capability, and polymers with lower fluorine content in molecule chains further boost the charge output, where metal/Kapton pairs demonstrated a charge promotion of over 2 times at the temperature of 383K with good durability during 90min measurement. The heat-excitation effect and charge durability in sliding freestanding-triboelectric-layer (SFT) mode triboelectric nanogenerator (TENG) is demonstrated as well, where the energy is promoted by over 3 times and the capacitor charging speed is doubled as well, with an energy promotion from 109.34 to 373µJ per cycle to successfully trigger a discharger. This work suggests a promising future of the heat-excitation effect as a new charge promotion strategy for TENG toward different applications in high-temperature environments.

Predicting the impact depolarization behavior of PZT-5H based on machine learning

In order to establish the relationship between the load and depolarized charge under stress waves, we established the stress depolarization experimental platform and obtained the time history curve of charge variation with the load. Then, we built a theoretical model of PZT-5H impact depolarization and physically described the model based on the characteristics of the experimental data and domain switching. Meanwhile, we obtained the uncertain parameters in the model by using the CBP neural network and the genetic algorithm. Finally, the effectiveness of the impact depolarization theory model was verified by comparing it with experimental values. The results indicated that the established PZT impact depolarization model can reflect the depolarization law of materials in the range of 0 ∼ 250 MPa stress waves. It provided a predictive method for the application of piezoelectric materials in extreme engineering such as contact fuses, pulse power supplies, and impact sensors.

Quantification of the Influence of Charge Variations on the Flow Behavior of Sheet Molding Compounds.

Using a newly developed flow test bench, several charge configurations were analyzed to quantify the influence of the charge configuration in the mold in sheet molding compound (SMC) manufacturing. A test bench was developed to satisfy the industrial needs for the incoming goods inspection as well as the need for the flow characterization of rheological models in the simulation. The test setup has a cylindrical opening for the charge placement, from where the material is pressed into a thin flow channel, forcing the material to reorient. A comparison was performed by juxtaposing the resulting compression pressure recorded during the process. The charge for this test series, placed into the cylindrical opening, has two basal configurations, one consisting of a stack of disks, and the second in a rectangular sheet rolled up into a spiral. Six charge variations were tested in total. The amount of material, the batch, the layering and the production direction of the sheet proved to have a significant influence on the necessary compression pressure. Guidelines about the recommended charge configurations could be derived for optimized production settings, such as a reduction in the compression pressure and modifications to the charge.