Magnitude Of Charge Research Articles

Influence of electric field on deformation of a drop in shear flow

The dynamics of a droplet in shear flow under the influence of an external electric field are investigated by performing extensive numerical simulations. The study is carried out by solving two-dimensional electrohydrodynamic equations, and the interface is captured using a volume-of-fluid approach. It is observed that with an increase in the drop size, a confined drop exhibits enhanced deformation and preferred orientation with the flow direction. For the case of dielectric fluids, the deformation of the drops can be either enhanced or reduced by varying the permittivity ratio and electric field strength. The nature of the polarisation forces acting at the interface can be either compressive or tensile depending on the magnitude of the permittivity ratio. The local electric field intensity inside the drop is significantly altered due to the permittivity contrast between the fluids. The computations for leaky dielectric fluids reveal that the deformation of the drop can be effectively tuned by altering the permittivity as well as the conductivity ratios. The nature of charge accumulation and the electric forces acting at the interface are critically dependent on the relative contrast between the electric properties of both the phases. The conductivity ratio decides the magnitude and nature of charge at the upper and lower portions of the droplet interface, thereby fundamentally maneuvering the droplet dynamics under the applied electric field.

Constraints from accretion onto a Tangherlini\u2013Reissner\u2013Nordstrom black hole

We investigate spherically symmetric, steady state, adiabatic accretion onto a Tangherlini–Reissner–Nordstrom black hole in arbitrary dimensions by using D-dimensional general relativity. We obtain basic equations for accretion and determine analytically the critical points, the critical fluid velocity, and the critical sound speed. We lay emphasis on the condition under which the accretion is possible. This condition constrains the ratio of mass to charge in a narrow limit, which is independent of dimension for large dimension. This condition may challenge the validity of the cosmic censorship conjecture since a naked singularity is eventually produced as the magnitude of charge increases compared to the mass of black hole.

Examining the Impact of Shipping Charge Fairness on Consumer Satisfaction and Behavior

AbstractFirms are increasingly recognizing that consumers' perceptions of price fairness should be considered when making logistics decisions at the firm level. A key element of price fairness is the shipping charges that consumers pay. This is especially critical with respect to online retail shipping charges as they represent a substantial portion of consumers' total cost and are visible to consumers before they place an order. Perceptions of the fairness of these prices are believed to impact online shoppers' selection of a retailer as well as influence subsequent purchase behavior. While large retailers may be able to leverage scale economies in shipping to offer free shipping on many orders, smaller firms may not be able to offer this to consumers. Thus, the general expectations of consumers are an important competitive factor in the environment, especially for the small and medium enterprises that are employers of 70 percent of US workers. This study assesses the impact of shipping charge fairness upon consumer satisfaction, repurchase, and positive word-of-mouth outcomes for a focal firm. Additionally, the moderating influences of shipping charge magnitude and consumer experience are examined. Consumer perceptions of fairness are found to influence satisfaction as well as willingness to repurchase and make positive referrals.

Vesicle formation by ultrashort alkyl-phosphonic acids and serine in aqueous solutions.

Vesicles possess unique biofilm structures and offer biomimetic advantages for drug and gene delivery. Herein, we report the spontaneous vesicle formation from ultrashort alkyl-phosphonic acids in the presence of amino acids. The aggregation characteristics and self-assembly structures of vesicles in aqueous solution were investigated by using dynamic light scattering, zeta potential, and cryo-transmission electron microscopy. We combined low-field nuclear magnetic resonance and Fourier transform infrared spectroscopy to study the H-proton-induced multilamellar vesicle formation. When we increased the molar fraction of serine, stable and closed spherical vesicles were formed at relatively low critical micelle concentrations. This transition of the self-assembled structure indicates that vesicle formation occurs when the chain length and the magnitude of the surface charge cause a fluctuation in the volume of the vesicle. Density functional theory reveals the critical role of the mixed alkyl-phosphonic acid/amino acid-enhanced electrostatic attraction between the head groups and hydrogen bonds associated with the aggregated states.

A comparison of the effects of natural organic matter on sulfidated and nonsulfidated nanoscale zerovalent iron colloidal stability, toxicity, and reactivity to trichloroethylene

Sulfidated nanoscale zerovalent iron (S-NZVI) is a new remediation material with higher reactivity and greater selectivity for chlorinated organic contaminants such as trichloroethene (TCE) than NZVI. The properties of S-NZVI and the effects of groundwater constituents like natural organic matter (NOM) on its reactivity are less well-characterized than for NZVI. In this study, S-NZVI (Fe/S mole ratio = 15) was synthesized by sonicating NZVI in a Na2S solution, yielding particles with greater surface charge, less aggregation, and higher reactivity with TCE compared to NZVI. The cytotoxicity of S-NZVI was not mitigated effectively due to the smaller size. The addition of Suwannee River humic acid (SRHA) increased the negative surface charge magnitude and dispersion stability and reduced the toxicity of both NZVI and S-NZVI significantly, but also enhanced the corrosion of particles and the formation of non-conductive film. The degradation rate constant (ksa) of both NZVI and S-NZVI was thus reduced with the increasing concentration of SRHA, which decreased by 78% and 60% to be 0.0004 and 0.0053 L m−2 h−1, respectively, with 200 mg C/L SRHA. Additionally, the performance of S-NZVI in field was evaluated to be depressed in simulated groundwater and the negative effect was exacerbated with increased concentration of SRHA. Hydro-chemical conditions like dissolved oxygen (DO), pH, and temperature also influenced the reactivity of S-NZVI. Hence, S-NZVI was a preferred candidate for in-situ remediation of TCE than NZVI. Nevertheless, the integrity of the FeS shell on S-NZVI influenced by NOM need to be considered during the long-term use of S-NZVI in groundwater remediation.

Structures and Interactions of Quantum Particles Based on the Energy Circulation Theory

Although the quark model is widely accepted, it is unknown what the origin of the electric charge of a quark is and why the charge magnitudes are fractional and different among the [Formula: see text] and [Formula: see text] quarks. Here we propose a novel scheme for quantum particles independent of quantum chromodynamics and quarks. We previously reported the energy circulation theory, in which the fundamental force works between antiparallel energy movements based on momentums, and forms an energy circulation. The electric charge is the momentum in the hidden dimension of an energy circulation in hidden–space dimensions. In this paper, we examine the interactions between energy circulations precisely covering the whole range of distance, and derive formulas for strong and weak nuclear interactions. The strong force is an inter-circulation interaction by the fundamental force. The weak interaction is an orthogonal separation of an energy circulation in space–space dimensions to two halves. A quantum particle consists of one or plural energy circulations in a unit space of radius of the lowest-frequency hidden dimension. We propose the respective compositions of energy circulations for major particles so that they as much conform to reported decays, spin and rest-mass values. This new model of particles provides potential solutions to unexplained issues from the Standard Model as follows: The new model presents the theoretical origin of the electric charge and its elementary charge. Because elementary components of hadrons are energy circulations instead of quarks, it is not required to introduce a fractional electric charge. A composition of elementary energy circulations for a quantum particle shows its electric charge and mass (rest energy) by the addition of those of elements. Furthermore, the model successfully exhibits strong and weak nuclear interactions as well as the electric force.

The Properties of Biologically Significant Chloramine Oxidants: Reactivity and Its Dependence on the Structure of the Functional Atom Group

A procedure for the direct photometric determination of rate constants for the oxidation of dithiothreitol (a thiol-compound example) by N-chlorotaurine and N-chloroglycine and their analogues that have a different structure of the reaction center was developed. The time dependences of the sum of the chloramine oxidant absorbance and the absorbance of dithiane (the product of the dithiothreitol conversion) were calculated for different values of the bimolecular rate constant. The value of the rate constant was considered as established when the best agreement between the calculated curve and the measured kinetic curve of absorbance was observed. The oxidative activities of monochloramine oxidants showed little difference: the rate constants for N-chlorotaurine, N-chloroglycine, and N-chloro-2,2-dimethyltaurine were equal to 170 ± 4, 235 ± 9.8, and 145 ± 4.3 M–1 s–1, respectively. When the reaction center structure was modified by introducing the substituents of the hydrogen atom into the chloramine group, the activities of the compounds changed dramatically: the rate constants for N-isopropyl-N-chlorotaurine, N,N-dichloro-2,2-dimethyltaurine and N-acetyl-N-chloro- 2,2-dimethyltaurine determined using the competitive kinetics method were 9 ± 0.5, 12 000 ± 950 and 25 300 ± 3000 M–1 s–1, respectively. The reactivity of N-chloroglycine and the structural analogues of taurine chloramine with respect to thiol-compounds correlates with the magnitude of the active chlorine charge. Predictions about the reactivity of unknown structural analogues of N-chloramino acids and N-chlorotaurine were obtained.

Charge properties and stability of 2D silicon carbide

In this paper, low-dimensional silicon carbide (SiC) obtained on the basis of SiC monolayers with a stoichiometric composition of 1:1 and a number of layers from 1 to 3 has been studied based on the quantum-chemical analysis of the structure and charge properties of this material. The redistribution of the electron density registered in a stack of graphene-like SiC layers allowed us to propose a method of identification of low-dimensional silicon carbide structures. The analysis of geometric and energy parameters made it possible to suggest the sustainable existence of two structural types of 2D-SiC, which differ in the way they are positioned within the layers. As a result of the analysis of the effective charge magnitude, the correlation between this parameter and the geometry of the optimized structure was established. It is proved that taking into account the charge properties of low-dimensional silicon carbide makes it possible to trace the structural changes in the system, identify a specific allotrope, and establish the order of the monolayers.

Molecular origin of AuNPs-induced cytotoxicity and mechanistic study

Gold nanoparticles (AuNPs) with diverse physicochemical properties are reported to affect biological systems differently, but the relationship between the physicochemical properties of AuNPs and their biological effects is not clearly understood. Here, we aimed to elucidate the molecular origins of AuNP-induced cytotoxicity and their mechanisms, focusing on the surface charge and structural properties of modified AuNPs. We prepared a library of well-tailored AuNPs exhibiting various functional groups and surface charges. Through this work, we revealed that the direction or the magnitude of surface charge is not an exclusive factor that determines the cytotoxicity of AuNPs. We, instead, suggested that toxic AuNPs share a common structural characteristics of a hydrophobic moiety neighbouring the positive charge, which can induce lytic interaction with plasma membrane. Mechanistic study showed that the toxic AuNPs interfered with the formation of cytoskeletal structure to slow cell migration, inhibited DNA replication and caused DNA damage via oxidative stress to hinder cell proliferation. Gene expression analysis showed that the toxic AuNPs down-regulated genes associated with cell cycle processes. We discovered structural characteristics that define the cytotoxic AuNPs and suggested the mechanisms of their cytotoxicity. These findings will help us to understand and to predict the biological effects of modified AuNPs based on their physicochemical properties.

Five computational developability guidelines for therapeutic antibody profiling

Therapeutic mAbs must not only bind to their target but must also be free from "developability issues" such as poor stability or high levels of aggregation. While small-molecule drug discovery benefits from Lipinski's rule of five to guide the selection of molecules with appropriate biophysical properties, there is currently no in silico analog for antibody design. Here, we model the variable domain structures of a large set of post-phase-I clinical-stage antibody therapeutics (CSTs) and calculate in silico metrics to estimate their typical properties. In each case, we contextualize the CST distribution against a snapshot of the human antibody gene repertoire. We describe guideline values for five metrics thought to be implicated in poor developability: the total length of the complementarity-determining regions (CDRs), the extent and magnitude of surface hydrophobicity, positive charge and negative charge in the CDRs, and asymmetry in the net heavy- and light-chain surface charges. The guideline cutoffs for each property were derived from the values seen in CSTs, and a flagging system is proposed to identify nonconforming candidates. On two mAb drug discovery sets, we were able to selectively highlight sequences with developability issues. We make available the Therapeutic Antibody Profiler (TAP), a computational tool that builds downloadable homology models of variable domain sequences, tests them against our five developability guidelines, and reports potential sequence liabilities and canonical forms. TAP is freely available at opig.stats.ox.ac.uk/webapps/sabdab-sabpred/TAP.php.

Effect of Relative Surface Charge of Colloidal Silica and Sapphire on Removal Rate in Chemical Mechanical Polishing

Many studies have looked at the chemical mechanical polishing (CMP) process of sapphire substrates. However, the research on the processing mechanism of the sapphire substrate is insufficient compared with semiconductor CMP processing. This paper focuses on the effect of the slurry pH on the removal rate of sapphire substrate in CMP. When the pH of the slurry is changed, the possible factors that can influence removal rate of sapphire include the zeta potential, abrasive agglomeration, and hydration reaction layers. The colloidal silica slurry used in this study did not show aggregation at any pH value. However, the zeta potential between the abrasive and the substrate changed remarkably at acidic and basic pH. The attractive force between the abrasive and substrate in acidic conditions is higher than that in basic conditions due to the relative surface charge. A higher attractive force caused by opposite charges makes more of the abrasive participate in the polishing process, which increases the removal rate in acidic conditions. However, the removal rate in basic conditions is higher than that in acidic conditions despite the repulsive relative charges. The reason for the higher removal rate in basic conditions seems to be the easier formation of a hydration layer, which is caused by the higher concentration of [OH]− in basic conditions. If the hydration effect is negligible, then the removal rate strongly depends on the magnitude of relative surface charges, which can be defined by the product of the zeta potentials of the abrasives and the substrate. If the product of the potentials is large, the probability of contact between the abrasives and the substrate is increased. Thus, the removal rate is increased. However, if the hydration layer forms, it plays a dominant role in determining the removal rate.

Detecting the topological charge of partially coherent electromagnetic vortex beams through the orientation angle of polarization

By analysis of the orientation angle of polarization (OAoP) of a partially coherent electromagnetic Gaussian Schell-model vortex (EGSMV) beam, we find that the OAoP distribution is the shape of petal and demonstrate an implicit rule that the number of petals is equal to twice the magnitude of the topological charge of the partially coherent EGSMV beam. The sign of the topological charge is related to the rotation direction of the petals. This novel rule provides an effective method for detecting the orbital angular momentum of a partially coherent electromagnetic vortex beam in applications such as free space optical communication and quantum information.

ISFET Based DNA Sensor: Current-Voltage Characteristic and Sensitivity to DNA Molecules

Dependency of both source-drain current and current sensitivity of nanosize ISFET biosensor vs. concentration of DNA molecules in aqueous solution theoretically is investigated. In calculations it is carried out effects concerning charge carriers distribution in current channel and concerning carriers’ mobility behavior in high electrical fields in the channel. The influence of DNA molecules on the work of ISFET biosensors is manifested by a change in the magnitude of the gate surface charge. Starting with fairly low concentrations of DNA, ISFET sensors respond to the presence of DNA molecules in an aqueous solution which is manifested by modulation of channel conductance and therefore the source-drain current changes of the field-effect transistor. It is shown that the current sensitivity with respect to concentration of DNA molecules linearly depends on the source-drain voltage and reaches high values.

Wave spectra of square-lattice domains in a quasi-two-dimensional binary complex plasma

Domains of the square lattice have been observed in a quasi-two-dimensional binary complex plasma. The longitudinal and transverse modes of the wave spectra were measured. To compare with the experiment, Langevin dynamics simulations of a binary mixture were carried out, where the non-reciprocal interactions between different species were modeled with a point-wake Yukawa potential. A strong dependence of the wave spectra on the relative magnitude of the point-wake charge is revealed.

Study on the Relationship between Stress and Charge of Coal Mass under Uniaxial Compression

This paper presents a new method to identify the stress concentration degree and stress distribution characteristics in front of working face in coal mine, based on the close relationship between charge and stress during fracture of coal mass. This method overcomes many disadvantages of conventional stress‐monitored methods. First, the stress and charge relationship of coal mass was established through damage theory and statistical strength theory. Then, the relationship between stress and charge was studied by a laboratory test, and finally, the field charge monitoring test was performed. The results show that there is a nonlinear relationship between loading stress (σ) and cumulative charge (Q), which can be represented by polynomials. The fitting results of the laboratory test between σ and Q conform to a cubic polynomial function, Q = aσ3 + bσ2 + cσ + d. It verifies the rationality of the theoretical relationship formula. The field monitoring results show that average charge is great and cumulative charge changes from rapid upward to sharp upward before roof falling. The magnitude and position of average charge and the upward trend of cumulative charge can be used to identify the stress concentration and stress distribution in front of working face, and the abnormal stress area can be predicted. The results can provide certain guidance for the forecast of rock burst in coal mine.

The Position of Solid Carbon Dioxide in the Triboelectric Series

The process of releasing liquid carbon dioxide from a fire extinguisher is accompanied by a strong static charging of the plastic material making up the extinguisher discharge horn. Firefighters often report an electric shock when operating CO2 extinguishers, but the origin of this electrostatic hazard is largely unknown. Here, we begin to investigate this phenomenon, and test the hypothesis of plastic samples being tribocharged on contact with rapidly flowing solid CO2. Using Faraday pail measurements, we show that non-conductive polymers gain a net static charge when brought in and out of contact with dry ice (solid CO2). These measurements of charge sign and magnitude give indirect evidence helping to place solid CO2 for the first time on the triboelectric series. Polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC) samples acquire a negative charge when rubbed against dry ice, whereas poly(methyl methacrylate) (PMMA), glass, and nylon surfaces become positively charged. Therefore, we suggest the position of dry ice in the triboelectric series to be close to that of materials with stable cations and unstable anions, possibly locating it between PMMA and PVC.

Electrostatic Mechanism for Depolymerization-Based Poleward Force Generation at Kinetochores

Experiments implicating bound volume positive charge at kinetochores interacting with negative charge at microtubule free ends have prompted our calculation of the force at kinetochores for chromosome poleward motility during mitosis. We present here a corroborating force calculation between positively charged Hec1 tails in kinetochores and negatively charged C-termini at microtubule free ends. Based on experimentally-known charge magnitudes on Hec1 tails and C-termini at microtubule free ends, an ab initio calculation of poleward (tension) force per microtubule that falls within the experimental range is demonstrated. Due to the locations of C-termini charges on concave sides of splaying microtubules, this attractive force between subsets of low curvature splaying microtubule protofilaments C-termini eventually fails for subsets of protofilaments with more pronounced curvature, thus generating poleward force as microtubules depolymerize in a dynamic coupling, as observed experimentally. The mechanism by which kinetochores establish and maintain a dynamic coupling to microtubules for force production during the complex motions of mitosis remains elusive, and force generation at kinetochores has emerged as a signature problem in chromosome motility. In agreement with experiment, two separate calculations show that attractive electrostatic interactions over nanometer distances account for poleward chromosome forces at kinetochores.

Thermal Field Stabilization of the Threshold Voltage of the Field Transistors of the Submicron Technology of the LSI

On the basis of the analysis of the volume correspondence of the phases in the active gate system Si-SiO2, the possibility of obtaining a negative charge in the shutter system of submicron LSI is shown. Such a technological method has been experimentally verified at low temperature oxidation of silicon, which is patented. Studies have established that the magnitude of charge at the interphase boundary can be significantly influenced by introducing into the oxidizing atmosphere of halogen-containing compounds.

Optical Orbital Angular Momentum Read-Out Using a Self-Assembled Plasmonic Nanowire

Orbital angular momentum (OAM) has emerged as an important parameter to store, control, and transport information using light. Recognizing optical beams that carry OAM at the nanoscale and their interaction with subwavelength nanostructures has turned out to be a vital task in nanophotonic signal processing and communication. The current platforms to decode information from different OAM modes are mainly based on bulk optics and requires sophisticated nanofabrication procedures. Motivated by these issues, herein we report on the utility of chemically prepared, individual plasmonic nanowire for OAM read-out. Our method is based on pattern recognition of coherent light scattering from individual nanowires that can be used as direct read-outs of two parameters of an OAM beam: magnitude of topological charge and its sign. All the experimental observations related to pattern formation are corroborated by three-dimensional numerical simulations. Given that pattern formation and recognition are exhaustively utilized in various computational domains, we envisage that our results can be interfaced with machine-learning methods, wherein direct read-out of OAM signals can be performed without human intervention. Such methods may have a direct implication on chip-scale robotics and chiral nanophotonic interfaces.

Charging ain't all bad: Complex physics in DyScO3

Although charging is ubiquitous in electron microscopy, its effects are typically avoided or ignored. However, avoiding charging is not possible in some materials, e.g. lanthanide scandates with well-ordered surfaces positively charge immensely under electron beam illumination because of their electronic structure, and ignoring charging can leave new science undiscovered. In this work, a combination of rapidly acquired electron energy loss spectra and cross-correlation were used to understand and overcome charging effects in DyScO3. A 5.4 eV band gap was extracted from the charging-corrected loss spectrum, in good agreement with previously reported band gaps, and a 3.8 eV in-gap peak was attributed to surface states via comparison with density functional theory calculations. Additionally, ultraviolet photoelectron spectroscopy measurements indicated that under some conditions well-annealed DyScO3 surfaces charge negatively causing upward band bending associated with occupied surface states in the gap. As was previously found in the case of positive charging under electron beam illumination with in-situ flexoelectric bending observations, the magnitude of negative charging under ultraviolet illumination is Zener tunneling limited in well-annealed DyScO3.