Fraction Of Charge Research Articles

Study on Phase Change Materials' Heat Transfer Characteristics of Medium Temperature Solar Energy Collection System.

Within the next five years, renewable energy is expected to account for approximately 80% of the new global power generation capacity, with solar power contributing to more than half of this growth. However, the intermittent nature of solar energy remains a significant challenge to fully realizing its potential. Thus, efficient energy storage is crucial for optimizing the effectiveness and dependability of renewable energy. Phase-change materials (PCMs) can play an important role in solar energy storage due to their low cost and high volumetric energy storage density. The low thermal conductivity of PCMs restricts their use for energy storage, despite their immense potential. Hence, the primary goal of this study is to experimentally investigate the energy storage capacity of two blended phase-change materials (paraffin and barium hydroxide octahydrate) through integration with a medium-temperature solar heat collection system. The experimental findings reveal that the blended PCMs possess the highest cumulative charge fraction (0.59), energy capacity, and low energy loss compared to each PCM alone. Furthermore, the phase change storage tank achieves higher heat storage (27%) and exergy storage efficiency (18%) compared to the stored tank water without any PCMs. The blended PCMs enhanced their performance, exhibiting improved interaction and excellent thermal storage properties across a range of temperatures, offering an opportunity for the design of an energy-efficient, low-cost storage system.

Influence of cationic species on the electrochemical performance of quinone derivatives

Quinones exhibit considerable promise as active components in energy storage applications, owing to their high theoretical storage capacity, well-defined redox potentials, rapid reaction kinetics, structural diversity, and proficiency in cycling both protons and metal ions. In this study, six quinone derivatives underwent comprehensive electrochemical and computational analyses using TBA+, H+, Li+, K+, Na+, Ca2+, and Mg2+-based electrolytes, aiming to uncover novel cycling chemistries with organic materials. Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV) elucidated the widely recognized 2H+/2e- redox process during proton cycling, as well as the two-step 1e- redox process in the presence of other cycling ions. Additionally, it was established that the quinone formal redox potential for different cycling chemistries followed the sequence TBA+ < K+ < Na+ < Li+ < H+, and cycling of the divalent cations resulted in potentials within the same range as those observed for proton cycling. DFT calculations provided insights into how cycling ions influenced the quinone formal redox potential, attributing it to the cation's ability to accommodate a portion of the bisolate anion charge upon reduction. Cations inducing a higher quinone formal redox potential and accommodating a larger fraction of the negative charge demonstrated a greater stabilizing effect on the reduced state. This stabilizing effect exhibited a strong correlation with the ionization energies of the respective cations.

Hybrid Modeling of Miniaturized 50 W Annular Hall Thruster

A 50-W-class annular Hall thruster is studied with a hybrid axial–radial two-dimensional model. Ions are described by a kinetic approach, whereas fluid conservation equations are solved for electrons. In such models, additional (anomalous) contributions must be added to the momentum-transfer electron collision frequency to obtain realistic values of the cross-field electron mobility. First, a parametric study is performed, where anomalous transport is described with a simple two-region model based on constant empirical parameters. The simulated global performance is subsequently compared with experimental measurements. Then, laser-induced fluorescence ion velocity measurements are employed to infer a continuous profile of the anomalous electron collision frequency along the channel centerline. The model reproduces the performance, the acceleration structure, the current oscillations, and the doubly charged ion fraction of the laboratory thruster. Measurements of the ion velocity distribution function highlight the presence of a slow ion population in the near plume. The production of the slow ions and their growth for increasing distances from the thruster channel exit is qualitatively reproduced by the model. The results obtained suggest that the generation and dynamics of the observed slow ions can be attributed to the presence of energetic electrons in the plume.

The effect of sodium chloride on the charge state of soot particles in a laminar diffusion flame

This study investigates the effect of sodium chloride on the charge state of soot nanoparticles formed in a laminar diffusion flame by measuring the soot particle size distribution, average charge per particle, and charge fraction at various heights within the flame. The well-studied Santoro burner with methane as the fuel (at 0.35 L/min) and co-flow air (at 70 L/min) was used, which produced a stable laminar diffusion flame with flame height of 61 mm. Samples of soot nanoparticles were extracted via a 0.3 mm orifice in a 3-mm stainless steel tubular probe at various heights above the burner and were immediately diluted by a factor of a few thousand for aerosol measurement. The effect of sodium chloride on a methane flame was investigated by comparing the experimentally measured data for methane-only and methane-NaCl flames. The addition of NaCl particles to the laminar diffusion flame did not have a significant effect on the particles in the nucleation region of the flame. The majority of the incipient soot particles in both flames are uncharged, and their sizes are nearly the same, with diameters of approximately 5 nm or less. However, the size of soot particles differs by approximately 10 % to 25 % between methane-only and methane-NaCl flames in the coagulation-dominated region of the flame. The net charge on soot particles within the coagulation region of the methane-only flames is negative, while it is positive with NaCl addition. The fraction of charged particles and ion concentration decreases with NaCl addition within the coagulation region. The study indicates that the smaller particle size observed in methane-NaCl flames may be attributed to reduced coagulation via altered particle charge states. These factors could be the major contributor to the variations in soot formation between methane-only and methane-NaCl flames. Novelty and Significance StatementThis research addresses a notable knowledge gap concerning the influence of NaCl, a prevalent component of hydraulic fracturing fluids, on soot particle behaviour in flames. By explaining the impact of NaCl on soot formation and charge states, the findings contribute to a deeper understanding of combustion processes in environments influenced by hydraulic fracturing operations, thereby informing strategies for reducing emissions and improving environmental sustainability in energy production. Overall, this article represents a significant advancement in the field of combustion science, with implications for environmental stewardship in energy production.This study provides valuable insights into how the introduction of NaCl alters the electrostatic properties of soot particles. This investigation expands upon existing knowledge by shedding light on the intricate mechanisms underlying soot formation and evolution in the presence of NaCl, elucidating its potential implications for combustion processes involving fossil fuels and industrial flaring.

Exploring the effects of three-finger toxins from Naja ashei venom on neuronal and immunological cancer cell membranes

Three-finger proteins are the most abundant toxins in the venom of Naja ashei, a snake species from the Elapidae family. This research aimed to describe the effects of varying charges of these proteins, isolated from Naja ashei venom using SEC and IEX chromatography. The study examined how differently charged three-finger toxin fractions interact with and affect neuroblastoma (SK-N-SH) and promyeloblast (HL-60) cells, as well as model Langmuir membranes and liposomes designed to mimic cellular lipid composition. Findings revealed that protein surface charges significantly impact cell survival (MTT assay), membrane damage (lactate dehydrogenase release, malondialdehyde formation), and the structural and electrochemical properties of model membranes (Langmuir membranes and zeta potential for liposomes and cancer cell lines). Results indicated that SK-N-SH cells, characterized by a higher negative charge on their cell membranes, interacted more effectively with positively charged toxins than HL-60 cells. However, the mechanism of these electrostatic interactions is complex. The research demonstrated that electrostatic and mechanical membrane modifications induced by venom proteins can significantly affect cell metabolism. Additionally, the total charge of the membrane, influenced by polar lipid components and phospholipid saturation, plays a decisive role in toxin interaction.

Extended rubber-elasticity model for non-Gaussian isotropic hyperelasticity of polyelectrolyte hydrogels undergoing curl-to-stretch transition

The nature of extremely high stretchability in hydrogels with a non-Gaussian elasticity has been extensively investigated. However, there are few studies on curl-to-stretch transitions of condensed polymer networks in polyelectrolyte hydrogels and their non-Gaussian hyperelasticity. In this study, an extended rubber-elasticity model was developed to investigate different mechanical behaviors, e.g., S-shaped and J-shaped stress-elongation ratio curves, where the condensed polymer networks in polyelectrolyte hydrogels undergo a curl-to-stretch transition and present a non-Gaussian isotropic hyperelasticity. A free-energy equation was formulated to describe the curl-to-stretch transitions and their thermomechanical conformations of condensed polymer networks, based on the free energy functions of elasticity, electrostatics and hydrophobicity. A constitutive relationship between stress and elongation ratio was then proposed to describe the non-Gaussian isotropic hyperelasticity in polyelectrolyte hydrogels, and effects of segment number, charged segment fraction and salt concentration on the mechanical behaviors were studied. Moreover, a segmental length criterion of condensed polymer networks was proposed to distinguish the S-shaped and J-shaped stress-elongation ratio curves. Finally, experimental data reported in literature were applied to verify the effectiveness of the proposed theoretical models. This study aims to provide a new thermomechanical criterion for non-Gaussian isotropic hyperelasticity in polyelectrolyte hydrogels undergoing the curl-to-stretch transition.

Fractional skyrme lines in ferroelectric barium titanate

We predict a topological defect in perfectly screened ferroelectric barium titanate which we call a skyrme line. These are linelike objects characterized by skyrmionic topological charge. As well as configurations with integer topological charge, the charge density can split into well-localized parts carrying a localized fraction of topological charge. We show that under certain conditions the fractional skyrme lines are stable. We discuss a mechanism to create fractional topological charge objects and investigate their stability. Published by the American Physical Society 2024

Structure and rheology of carboxymethylcellulose in polar solvent mixtures

We study the conformational, conductometric and rheological properties of semiflexible polyelectrolyte carboxymethyl cellulose in mixtures of water and three non-solvents (ethanol, isopropanol and acetone). Small angle x-ray scattering measurements of the correlation length reveal that the local conformation of the carboxymethyl chain is unchanged by the presence of a non-solvent, even for solutions not far from the solubility boundary. Rheological measurements confirm the invariance of the correlation length upon non-solvent addition. Conductivity measurements show that as the non-solvent content is increased, the fraction of condensed counterions increases, presumably due to the lowering of the dielectric constant of the solvent media. These results therefore show that under room temperature and pressure, the conformation of polyelectrolyte chains is independent of the effective charge fraction of the backbone. We suggest this occurs because the bare Kuhn length (≃10nm) is much larger than electrostatic blob size (≃1−2nm).

High-glide refrigerant blends in high-temperature heat pumps: Part 2 – Inline composition determination for binary mixtures

Refrigerant mixtures are frequently used in air-conditioners and heat pumps. However, mixtures with high glides of 30 K and more during evaporation are rare, partially because there is an increased concern about composition shifts within the system. An easy and reliable inline composition measurement could alleviate these concerns and simplify the handling of systems with high-glide mixtures. This study investigates six composition determination methods, which are all non-invasive, five of which can be conducted during system operation. All methods were applied to all available mixtures in a dataset of 380 data points. The binary and ternary mixtures tested consist of the refrigerants R-1233zd(E), R-1336mzz(Z), R-1234yf, R-1224yd(Z), and R-32. Each method was applied to all datapoints collected with a certain refrigerant mixture at varying operating conditions. The average of the calculated mass fraction was then compared to the manually charged mass fraction. For the density method, this difference of the calculated and measured mass fraction was always less than 0.03 and usually smaller than 0.01 across all tested mixtures. Most other methods performed well with deviations typically less than 0.05. Some of the methods require only low-cost sensors like thermocouples and pressure transducers. Property data of ternary mixtures is also discussed in the study but a composition determination, theoretically possible combining any two of the six methods, is not attempted in this study.

Experimental investigation on CO2-based zeotropic mixture composition-adjustable system

CO2 is a promising natural working fluid for its environment-friendly, property-stable and low-cost, and CO2-based zeotropic mixture could enhance the comprehensive performance of combined cooling and power cycle (CCP). Generally, CCP operates in a wide temperature range, and the fixed operating composition could not realize the optimal match for two sub-cycles. Zeotropic mixture composition adjustment could realize targeted thermal match of sub-cycles and further enhance the performance of CCP. However, systematic research on composition-adjustable CCP is limited in theoretical simulation, and there is still a lack of experimental evidence for the performance enhancement of composition adjustment on CCP. Besides, the feasibility of composition adjustment on CCP has not been fully verified through experimental method yet. In this study, an experimental prototype of CO2-based composition-adjustable CCP is established, the approach to realize composition adjustment is investigated, and the systematic test is carried out. Experimental results show that the introduction of composition adjustment is beneficial to the performance of CCP. Under the same boundary conditions and similar refrigeration conditions, composition-adjustable CCP could export 13.72 % more net power than composition-fixed CCP when the initial charged CO2 mass fraction equals 0.246, and the improvement is more apparent when the initial charged composition gets larger.

Fractionation and characterisation of sialylated-mucin glycoprotein from edible birds' nest hydrolysates through anion exchange chromatography

Edible bird's nest (EBN) is made up of sialylated-mucin glycoprotein with various health benefits due to its high antioxidative activity. However, as a macromolecule with distinct charged sialic acid and amino acids, fractions with different charges would have varied physicochemical properties and antioxidant activity, which have not been studied. Therefore, this study aimed to fractionate and purify the enzymatic hydrolysed of cleaned EBN (EBNhc) and EBN by-product (EBNhbyp) through anion exchange chromatography (AEC), and determine their molecular weights, physicochemical properties, and antioxidative activities. Overall, 26 fractionates were collected from enzymatic hydrolysate by AEC, which were classified into 5 fractions. It was found that the positively charged fraction of EBNhc (CF 1) and EBNhbyp (DF 1) showed the significantly highest (p < 0.05) soluble protein contents (22.86 and 18.40 mg/g), total peptide contents (511.13 and 800.47 mg/g) and ferric reducing antioxidant power (17.44 and 6.96 mg/g) among the fractionates. In conclusion, a positively charged fraction (CF 1 and DF 1) showed more desired physicochemical properties and antioxidative activities. This research suggests the potential of AEC fractionation as a technology to purify EBN and produce positively charged EBN fractionates with antioxidative potential that could be applied as food components to provide health benefits.

Effect of the Soliton Width on Nonequilibrium Exchange Phases of Anyons.

Unlike bosons and fermions, quasiparticles in two-dimensional quantum systems, known as anyons, exhibit statistical exchange phases that range between 0 and π. In fractional quantum Hall states, these anyons, possessing a fraction of the electron charge, traverse along chiral edge channels. This movement facilitates the creation of anyon colliders, where coupling different edge channels through a quantum point contact enables the observation of two-particle interference effects. Such configurations are instrumental in deducing the anyonic exchange phase via current cross-correlations. Prior theoretical models represented dilute anyon beams as discrete steps in the boson fields. However, our study reveals that incorporating the finite width of the soliton shape is crucial for accurately interpreting recent experiments, especially for collider experiments involving anyons with exchange phases θ>π/2, where prior theories fall short.

Characterizing Precipitation Behaviors of H− in the Martian Atmosphere

AbstractSolar wind protons can charge exchange with the extensive hydrogen corona of Mars, resulting in a significant flux of energetic neutral atoms (ENAs). As these solar wind hydrogen ENAs precipitate into the upper atmosphere, they can experience electron attachment or detachment, resulting in populations of H− and H+, respectively, with upstream velocity. We seek to characterize the behavior of H− in the ionosphere of Mars through a combination of in situ data analysis and mathematical models. Observations indicate that measurable H− precipitation in the ionosphere of Mars is rare, occurring during only 1.8% of available observations. These events occur primarily during high energy solar wind conditions near perihelion. We also compare H− fluxes to those of H+ and find that H− fluxes are ∼4.5 times less than H+, indicating preferential conversion of hydrogen ENAs to H+. We develop a simple model describing the evolution of the charged and neutral fraction of ENAs and H− ions versus altitude. We find that 0.29%–0.78% of ENAs are converted to H− for solar wind energies 1–3 keV. We also predict that the effects of photodetachment on the H‐H− system are non‐negligible.

Purification of an Acidic Polysaccharide with Anticoagulant Activity from the Marine Sponge Sarcotragus spinosulus.

Thromboembolic conditions are the most common cause of death in developed countries. Anticoagulant therapy is the treatment of choice, and heparinoids and warfarin are the most adopted drugs. Sulphated polysaccharides extracted from marine organisms have been demonstrated to be effective alternatives, blocking thrombus formation by inhibiting some factors involved in the coagulation cascade. In this study, four acidic glycan fractions from the marine sponge Sarcotragus spinosulus were purified by anion-exchange chromatography, and their anticoagulant properties were investigated through APTT and PT assays and compared with both standard glycosaminoglycans and holothurian sulphated polysaccharides. Moreover, their topographic localization was assessed through histological analysis, and their cytocompatibility was tested on a human fibroblast cell line. A positive correlation between the amount of acid glycans and the inhibitory effect towards both the intrinsic and extrinsic coagulation pathways was observed. The most effective anticoagulant activity was shown by a highly charged fraction, which accounted for almost half (about 40%) of the total hexuronate-containing polysaccharides. Its preliminary structural characterization, performed through infrared spectroscopy and nuclear magnetic resonance, suggested that it may consist of a fucosylated chondroitin sulphate, whose unique structure may be responsible for the anticoagulant activity reported herein for the first time.

Modeling titanium dioxide (TiO2) nanoclusters using a 2D sectional method with molecular dynamics (MD) determined coagulation rates

Accurate prediction of the particle size distribution (PSD) evolution of growing nanometer scale particles is important in designing gas-phase synthesis reactors for the production of nanomaterials. Towards improved predictions of growth, we model the evolution of the PSD of 1-4 nm TiO2 particles from the decomposition of titanium tetraisoproxide (TTIP) using a two-dimensional (2D) sectional method, uniquely with coagulation rates derived from molecular dynamics (MD) trajectory calculations which account for detailed particle–particle interactions. The PSDs predicted by the 2D sectional method are compared to recent experimental measurements of PSDs in the 1-3 nm range in a flow tube reactor. The nucleation of particles is modeled based on prior mobility measurements of ions attributed to TTIP and their decomposition, with the specific nucleation rate here fitted as a fraction of base nucleation rate (k) derived from these prior measurements. In the 2D sectional model, we examine the influence of the initial (nucleated) particle charge distribution on the PSD, with different coagulation rate coefficients for neutral-charged and charged-charged particle collisions. With the MD-derived coagulation rate coefficients, we find that using nucleation rate coefficients between 0.005k and 0.03k leads to strong agreement between modeled PSD and measured PSD for a wide variety of experimental residence times, initial TTIP concentrations and temperatures. Increasing the charge fraction from 0% (uncharged) to 80% (bipolar) does not result in a significant change in the PSD, because the particles rapidly self-neutralize through coagulation based on the simulation results. The results with MD-derived coagulation rate coefficients are compared to those of the sectional method with classical kinetic theory of gases (KTG) rates with a constant enhancement factor to account for potential interactions. Through comparison, we find that the predictions from the classical KTG model consistently exhibit weaker coagulation rates than the MD-derived model during the PSD evolution.

Fuel effects on the electrostatic control of charged droplet trajectories

The use of electrostatic fields to control the trajectory of charged droplets is investigated as a new technology to enhance mixing in liquid-fuelled combustors. The canonical configuration of a spray in crossflow is numerically studied with a focus on the effects of the fuel type on the onset of charge-induced breakup and droplet trajectories for a range of bulk flow velocities and electrostatic field strengths at conditions relevant to gas turbine applications. The investigated fuels are ethanol, n-heptane, and n-decane. Operational maps for each fuel are provided to assist the selection of the external electrostatic field required to achieve a balance between the drag and electrostatic forces, and enable a system design that considers fuel flexibility. The results demonstrate that the fuel type has an important impact on the diameter at which the charge-induced breakup is achieved, which mainly depends on the droplet equilibrium temperature. It is also shown that, for cases where the droplet net charge is fixed to a given fraction of the maximum possible charge (based on the Rayleigh limit), the temperature of the droplet at injection could be used as a parameter to control the onset of secondary breakup. Analysis of the strength of the electrostatic field necessary to achieve droplet stabilisation in a bulk flow shows that a balance between the electrostatic and drag forces can only be achieved for relatively low values of the bulk flow velocity, if the strength of the electrostatic field is kept below the breakdown limit of the carrier phase. This balance mainly depends on the droplet net charge and flow conditions, whereas the effect of the type of fuel on the drag force is less important. When the charge is imposed as a fraction of the maximum possible value at injection, for low values of the bulk flow velocity, the strength of the electrostatic field that balances the drag tends to become independent of the droplet diameter for a wide range of droplet sizes. Further investigation of the trajectories of evaporating droplets demonstrates that, although affected by the type of fuel through the evaporation rate, with the same settings of the electrostatic field, it is possible to achieve evaporation in a confined region for all the fuels and ambient conditions studied in this work once the initial droplet charge and initial droplet diameter are fixed. The present findings offer new insights for the development of future technologies for fuel preparation with enhanced mixing and fuel flexibility.

Instability of membranes containing ionizable cationic lipids: Effects of the repulsive range of headgroups and tail structures

The stability of membranes formed by ionizable cationic lipids, which constitute the primary components in lipid nanoparticles capable of endosomal escape, is explored using coarse-grained dissipative particle dynamics. Three types of ionizable model lipids with different tail structures are considered. Endosome acidification causes the ionization of lipids, leading to an increased repulsive range between their headgroups. When electrostatic repulsion is modeled as a conservative force with a long-range cutoff distance (rc,HH), the membrane and vesicle experience a loss of structural integrity and develop holes as rc,HH is beyond a critical value, which varies with the tail structure. When Coulombic repulsion is explicitly incorporated and intensified, a fully ionized lipid membrane undergoes a loss of structural integrity, displaying a qualitative similarity to the effect observed with the increase in rc,HH on the membrane stability. Qualitatively similar results are obtained for partially ionized membranes as the fraction of charged lipids increases. The stability of a mixed lipid membrane containing both ionizable and conventional lipids is also investigated. The disruption of the bilayer structure occurs for a sufficiently high charged fraction. The membrane instability can be attributed to the decrease in the packing parameter, which significantly deviates from unity as the interaction range increases.

Multivalent Salt-Induced Self-Assembly of Amphiphilic Polyelectrolytes of Different Charge Fractions: A Coarse-Grained Molecular Dynamics Simulation Study.

Amphiphilic polymers with both hydrophobic and hydrophilic blocks are of great interest for their potential applications in drug delivery. Their self-assembly behavior in response to environmental factors like ion charge and multivalent salt concentration has been the subject of recent investigation. Our study utilizes coarse-grained molecular dynamics simulations to investigate the aggregation behavior of amphiphilic copolymers upon introducing tetravalent salt at varying charge fractions. We identify a critical concentration, Cs*, where the aggregation number reaches its maximum for each charge fraction, followed by a subsequent decrease at the excessive salt regime. This study reveals distinct morphological transitions in response to increasing salt concentration and decreasing charged fractions, namely, (i) stable dispersed micelles, (ii) a singular micelle comprising all copolymer chains, and (iii) redispersed micelles, particularly evident at lower charged fractions. Our study highlights the significant influence of tetravalent salt and charge fractions of polyelectrolyte chains on the self-assembly behavior of polyelectrolyte copolymers.

Phase and Order Behavior of Charged Asymmetric Diblock‐Copolymer Melts in Bulk

AbstractThe phase and order behavior of charged asymmetric diblock‐copolymer melts is studied by using coarse‐grained molecular dynamics simulation. One of the blocks is made charged and other one is kept neutral, and the study systematically explores how the charged diblock‐coploymer responses as the charge fraction of the charged block is varied from 10% to 50%. When charge fraction increases, the study finds ordered transitions from interconnected cylinder‐like structures to lamellae, then to gyroid structures. It is also found that domain size of the obtained equilibrium morphology decreases slightly with the increase in charge fraction of the charged block.

A formalism for extracting track functions from jet measurements

The continued success of the jet substructure program will require widespread use of tracking information to enable increasingly precise measurements of a broader class of observables. The recent reformulation of jet substructure in terms of energy correlators has simplified the incorporation of universal non-perturbative matrix elements, so called “track functions”, in jet substructure calculations. These advances make it timely to understand how these universal non-perturbative functions can be extracted from hadron collider data, which is complicated by the use jet algorithms. In this paper we introduce a new class of jet functions, which we call (semi-inclusive) track jet functions, which describe measurements of the track energy fraction in identified jets. These track jet functions can be matched onto the universal track functions, with perturbatively calculable matching coefficients that incorporate the jet algorithm dependence. We perform this matching, and present phenomenological results for the charged energy fraction in jets at the LHC and EIC/HERA at collinear next-to-leading logarithmic accuracy. We show that higher moments of the charged energy fraction directly exhibit non-linear Lorentzian renormalization group flows, allowing the study of these flows with collider data. Our factorization theorem enables the extraction of universal track functions from jet measurements, opening the door to their use for a precision jet substructure program.