Electric Interaction Research Articles

Simple Method for Optical Detection and Characterization of Surface Agents on Conjugated Gold Nanoparticles.

In this article, we propose a simple method to calculate electrical permittivity and refractive index of surface agents of gold nanoparticles (Au NPs), in which it is possible to find the refractive index of surface agents shell by using the absorption peak of the gold nano-colloid. One of the usual tests for detection of surface agents is colorimetric methods based on the change of color of Au NPs. The color change is mainly due to the shift of localized surface plasmon resonance which is related to electrical interactions of surface agents. Although there are many mathematical models for simulating the absorption spectrum and calculating the plasmonic peak, using them is not simple and possible for everyone due to the need for programming. Here, the necessary simulations have been performed for different values ​​of refractive index of surface agents and particle size, and absorption peaks have been obtained. Using numerical methods, a simple formula is obtained between the wavelength of plasmonic peak, the ratio of hydrodynamic diameter to Feret size of the particles, and the refractive index of the surface agents. This method can help researchers to obtain the refractive index and consequently the type or concentration of surface agents around Au NPs without the need for programming or complex mathematical operations. It can also open new horizons in analyzing colorimetric diagnosis of biological agents such as viral antibodies, antigens, and other biological agents.

Eu2+/Ce3+-doped NaAlSiO4 selective occupation-induced emission structure unit evolution and its luminescence characteristics

NaAlSiO4: xEu2+,yCe3+ blue-red phosphors were prepared by high-temperature melting-icy quenching-heat treatment. The effects of emission structure unit evolution, microstrain, microcrystalline size and selective occupation on the luminescence characteristics of the prepared phosphor were systematically studied by powder X-ray diffraction pattern (XRD) and photoluminescence spectroscopy (PL). In the structure of NaAlSiO4: 2%Eu2+, 2%Ce3+ hexagonal crystalline sodium nepheline, Eu2+ ions occupy the Na+ (II) position to form a EuNa+(II)2+ luminescent structure unit, and Ce3+ ions occupy the Na+ (I) position to form a CeNa+(I)3+ luminescent structure unit. The NaAlSiO4: 2%Eu2+/NaAlSiO4: 2%Ce3+ emits 555 nm yellow-green light/395 nm blue-violet light under the excitation of 354 nm/298 nm, respectively, which is derived from the 5d-4f transition of Eu2+ and Ce3+. There is energy transfer of Ce3+→Eu2+ in the sodium nepheline matrix, of which the transport pathway is m EuNa+(II)2+ ←O←n CeNa+(I)3+ →O→m EuNa+(II)2+, and the transport mechanism is electric quadrode-electric quadrupole interaction, and the energy transfer efficiency reaches 98.6%. The sodium nepheline NaAlSiO4: 2%Eu2+, 2%Ce3+ phosphor with energy level barrier 0.386 eV, possesses good thermal stability. This single-phase aluminosilicate multicolor phosphor has potential application value for WLED illumination and PDP display.

Downconverted significant luminescence enhancement and structural confinement of a dichromatic nanophosphor for potential applications in NUV-triggered cool pc-WLEDs

Trivalent rare-earth ions activated phosphor-converted near ultraviolet (NUV) triggered white light-emitting diodes (WLEDs) are nowadays being explored as a prominent light source, in the field of lighting. Herein, we prepared a sequence of single-phase Gd2O3:Dy3+,Li+nanophosphor via chemical co-precipitation techniques for the applications in cool pc-WLEDs. To examine the crystal structure, luminescent characteristics, and potential applications of WLEDs, a systematic and comprehensive analysis was conducted. This study extensively investigated the effect of Li+ on the Gd2O3:Dy3+white-emitting nanophosphor. The phase purity and crystal structure of nanophosphors were characterized via powder X-ray diffraction (XRD) analysis. Rietveld refinement clearly quantified that the Gd2O3 host possesses two non-equivalent cationic sites that are coordinated sixfold. The interior morphology and elemental composition were illustrated by high-resolution transmission electron microscopy (HR-TEM) and energy dispersive spectroscopy (EDS). These nanophosphors effectively exhibit dichromatic significant photoluminescence (PL) emission bands of Dy3+ ion for blue and yellow color at 486 and 574 nm, while triggered in the NUV range. The blending of blue and yellow color lights yields a broad spectrum of light that appears white color to the human eye. Besides, it has been observed that the incorporation of Li+ significantly enhances the PL-emission intensity. The critical distance between Gd3+ and Dy3+ was determined, and it showed that the electric multipolar interaction was responsible for the energy transfer quenching mechanism. The colorimetric performance reveals that the CIE coordinates fall within the white region of the color space and that the correlated color temperature (CCT) is substantially higher than 4000 K. The lowest color purity (CP) was found to be 4.0% for x = 2 at.%Li+ ion concentration under excitation wavelength 350 nm. These findings suggest that the prepared nanophosphors are a suitable candidate for application in NUV-triggered cool-WLEDs.

Connecting Colloidal Forces to the Equilibrium Thickness of Particulate Deposits on a Substrate in Contact with a Suspension Using Classical Density Functional Theory

We study contributions of colloidal forces, i.e., hydrophobic, van der Waals, and electrical double layer interactions, to the thickness of a colloidal deposit in equilibrium with an aqueous suspension by using classical density functional theory, which we expand to obtain a Ginzburg-Landau type energy functional. We regard colloidal particles as clusters of molecular segments-a reminiscent of polymer statistical physics and of the classic Hamaker treatment of van der Waals interactions between particles. This approach appropriately accounts for the integral interaction energy between colloidal particles, which may take magnitudes of many times the characteristic molecular thermal energy kBT (Boltzmann constant times temperature). The analysis highlights the well-known insight that entropy is mostly governed by the solvent molecules and gives physical values to the statistical coefficients in a Ginzburg-Landau type energy functional.

Robust Nuclear Spin Entanglement via Dipolar Interactions in Polar Molecules.

We propose a general protocol for on-demand generation of robust entangled states of nuclear and/or electron spins of ultracold ^{1}Σ and ^{2}Σ polar molecules using electric dipolar interactions. By encoding a spin-1/2 degree of freedom in a combined set of spin and rotational molecular levels, we theoretically demonstrate the emergence of effective spin-spin interactions of the Ising and XXZ forms, enabled by efficient magnetic control over electric dipolar interactions. We show how to use these interactions to create long-lived cluster and squeezed spin states.

Low carbon and economic dispatch of the multi-microgrid integrated energy system using CCS-P2G integrated flexible operation method

ABSTRACT The multi-microgrid integrated energy system offers multiple effective approaches to promote clean energy utilization as well as carbon emission reduction, etc. Combined with stepped carbon trading mechanism, it proposes a multi-microgrid (MMG) system with CCS-P2G integrated flexible operation method for optimal scheduling. Firstly, based on the microgrids’ “source-load” characteristic, electricity sharing between the source and load type microgrids can be achieved. Secondly, the CCS-P2G integrated flexible operation method is proposed, i.e. introducing HFC (Hydrogen Fuel Cell) and HES (Hydrogen Energy Storage) in P2G can enhance the utilization effect of hydrogen. Moreover, introducing carbon storage equipment in CCS, which can effectively solve the situation of unsynchronized operation times of CCS and P2G. Finally, introducing stepped carbon trading mechanism can be a further way of limiting carbon emission. Based on the above, MMG’s optimal dispatch model has established with objective of minimizing total operation cost by considering economic performance and carbon emission of the MMG system. Above optimal dispatch model is a mixed integer linear problem, which is solved using CPLEX solver. Simulation results show that electric energy interaction between source-type and load-type microgrids enhances renewable energy utilization rate. Compared to CCS-P2G cooperative operation method, the single-day carbon emissions and total operation cost of multi-microgrid system using CCS-P2G integrated flexible operation method are reduced by 37.02% and 6.80%, respectively. Meanwhile, when the stepped carbon trading mechanism was introduced, multi-microgrid system’s single-day carbon emissions is reduced to 5.40% compared to when normal carbon trading was considered, further constraining MMG’s carbon emissions.

Experimental Investigation on the Arc Damage and Fatigue Crack Initiation Risk of Copper-Silver Contact Wires

Contact wires are subjected to both mechanical and electrical interactions while electrical energy is transmitted to the trains by overhead lines and train pantographs. Particularly, an increase in the speed of trains can result in greater contact force fluctuations and more intense pantograph arcs, therefore, these mechanical and electrical interactions have potential to drive failure of Overhead Line Equipment (OLE) conductors. In this paper, the effect on fatigue crack initiation risk of material ablation from the contact wire surface due to arc discharge is experimentally investigated under laboratory conditions. Fatigue life, crack propagation directions and crack initiation locations in arc-exposed copper silver contact wire samples are compared with those in comparable arc-free samples. The results show that under the conditions of having arc damage on the contact wire surface could result in 50% shorter fatigue life compared to arc-free contact wires. It is often considered that wear rather than fatigue cracking defines the life of the contact wires, but under some conditions with the combination of arcing, the fatigue life in the contact wire can become the controlling failure risk. Therefore, in determining system life and maintenance requirements the fatigue life of the contact wire should be taken into consideration at locations where the arc discharge is likely.

The Parameters of the Hyperfine Structure of 57Fe Nuclei in FeBO3 and Fe0.91Ga0.09BO3 Single Crystals

The parameters of the hyperfine interaction of 57Fe nuclei in single crystals of iron borate FeBO3 and its isostructural solid solution Fe0.91Ga0.09BO3 have been determined by Mössbauer spectroscopy. A theoretical model has been developed to describe resonant transitions of iron nuclei in the approximation of a combined magnetic dipole and electric quadrupole hyperfine interaction, taking into account the statistical distribution of Ga and Fe over octahedral positions in the Fe0.91Ga0.09BO3 crystal. It has been established that even a low Ga concentration leads to a significant change in the hyperfine structure of the 57Fe nuclei inFeBO3, which manifests itself in the appearance of additional components in the Mössbauer spectra of the Fe0.91Ga0.09BO3 single crystal.

Synthesis and up-conversion luminescence of Ho3+ and Yb3+ co-doped La7P3O18 phosphors

Ho3+ and Yb3+ co-doped La7P3O18 up-conversion phosphors were prepared by a high-temperature solid-state process. XRD results reveal that the samples are mixtures of monoclinic structure La7P3O18 crystals with P21/n space group and minor LaPO4 crystals. UV—Vis DRS results indicate that La7P3O18 crystal is an indirect semiconductor with an optical band gap of 4.10 eV. After 980 nm laser excitation, the Ho3+ and Yb3+ co-doped La7P3O18 phosphors show the characteristic blue (486 nm), green (550 nm), and red (661 nm) luminescence peaks of Ho3+ ions. The peak at 661 nm dominates in the up-conversion luminescence spectra of samples. Meanwhile, with the increase of Ho3+ and Yb3+ doping content, the up-conversion luminescence intensity increases first and then decreases. By increasing the doping contents of Ho3+ and Yb3+ up to 1 at.% and 10 at.%, respectively, concentration quenching may appear by an electric quadrupole– electric quadrupole interaction process. The pumping power dependence of luminescence indicates that the green and red emissions of samples are excited by a two-photon absorption process. The color coordinates of Ho3+ and Yb3+ co-doped La7P3O18 crystals locate in the orange—red region.

The roles of dopant concentration and defect states in the optical properties of Sr2MgSi2O7:Eu2+, Dy3+

The blue-emitting Sr2MgSi2O7:Eu2+,Dy3+ was prepared by sol-gel method. The effects of dopant concentration on crystal structure, photoluminescence and afterglow properties were studied. Based on First-principles calculations, the formation difficulty and electronic structures of intrinsic defects and the external defects caused by doping Eu, Dy were predicted, and the defect-dominated persistent luminescence mechanism was proposed. The results showed that when the content of Eu2+ reached 0.03 mol%, Sr2MgSi2O7:Eu2+,Dy3+ had the best luminescence performance. After exceeding this content, the concentration quenching caused by electric dipole-dipole interaction would occur, leading to a decrease in luminescence intensity. The oxygen vacancy as an intrinsic defect was more easily formed in Sr2MgSi2O7. The impurity levels in the forbidden band, which were introduced by oxygen vacancies and Dy doping defects, can effectively capture and release Eu electrons. It is beneficial to prolong the afterglow duration of Eu 4f65d1→Eu 4f7. This work reveals the electron transition and capture paths in the luminescence of Sr2MgSi2O7:Eu2+,Dy3+, which has reference significance for designing defect structures and optimizing optical properties.

Multiphysics Simulation of the Shape Prediction and Material Removal Rate in Electrochemical Machining Process

ABSTRACT The electrochemical machining process involves electrical and chemical processes while removing materials from the workpiece. Electrochemical machining (ECM) lacks accurate models for predicting the shape and material removal rate during the ECM process. This limits the ability to optimise the process and predict the final product geometry, which is crucial for industrial applications. This research mainly focused on the modelling and simulation of material removal from the workpiece using COMSOL Multiphysics software. This research involves developing a mathematical model that describes ECM’s electrical, chemical, and mechanical interactions. The model is based on electrochemistry, fluid dynamics, and solid mechanics principles and will be solved using numerical simulation techniques. Various workpiece materials considered in this investigation include Aluminium, Nickel, Stainless Steel, and Tungsten, whereas copper is electrode material. The effects of the various parameters, such as workpiece materials, the voltage applied during machining, and electrolyte conductivity on the material removal rate are being investigated. In addition, the shape of the machined workpiece is also predicted. The results of this research provide a deeper understanding of the underlying physics of the ECM process and lead to the development of more accurate models for predicting the shape and material removal rate during ECM.

Charge‐Driven Self‐Assembled Microspheres Hydrogel Scaffolds for Combined Drug Delivery and Photothermal Therapy of Diabetic Wounds

AbstractThe treatment of diabetic wound remains a big clinical challenge. Hydrogel that can provide physical barrier and humidity displays amazing potentials for managing the diabetic wounds healing. Herein, a new charge‐driven self‐assembled microsphere hydrogel scaffold (SMHS) is reported based on an electric charge interaction, by combining use of black phosphorus (BP)‐contained chitosan methacryloyl (CS) microspheres with positive charge and basic fibroblast growth factor‐contained hyaluronic acid methacryloyl (HA) microspheres with negative charge. The weak charge attraction among microspheres gives the SMHS the injectable characteristic. Due to the existence of BP, near‐infrared (NIR) irradiation has obvious effects on the degradation and drug release behaviors of SMHS. Significantly, SMHS that combines the short‐term physical (photothermal) intervention and long‐term chemical (drug release) intervention may be promising in spatio‐temporal regulation of regenerative microenvironment. SMHS with NIR irradiation (SMHS+NIR) can promote cell proliferation, cell migration, angiogenesis and macrophage polarization. Moreover, in diabetic rat skin wounds, SMHS+NIR significantly accelerates the wound healing process by simultaneously inhibiting the inflammatory response, promoting angiogenesis and tissues remodeling. The outcome of this research not only provides a biomaterial for diabetic wounds healing, but also demonstrates a new strategy for designing novel hydrogel‐based biomaterials which have the free editing and combination functions.

Theoretical investigation of rotating magnetocaloric effect in PrRu2

The magnetic anisotropy in the cubic ferromagnetic PrRu2 compound (TC = 34 K) is due to the crystalline electrical field interaction. Using a model Hamiltonian which includes the crystalline electrical field, exchange and Zeeman interactions we calculated the rotating magnetocaloric effect, considering the magnetic field changes along the three main cubic crystallographic directions 〈001〉, 〈011〉 and 〈111〉. The influence of the spin reorientation, along the field directions, on the magnetocaloric potentials were quantitatively obtained and discussed.

Sesame seed protein: Amino acid, functional, and physicochemical profiles

Sesame (Sesamum indicum L.) is an erect herbaceous annual plant with flat seeds. It is one of the oldest cultivated oilseed plants in the world, especially popular in Africa and Asia.
 The present research objective was to describe a sesame protein isolate, i.e., its amino acid profile, functional and physicochemical properties, zeta potential, and hydrodynamic diameter. The surface charge and hydrodynamic diameter in aqueous solutions were obtained for standard sesame seeds, defatted sesame seeds, and the sesame protein isolate.
 Defatted sesame seeds yielded the following optimal parameters: salt concentration – 0.6 M, pH – 7, iso-electric point (pI) – 4. The sesame protein isolate was rich in methionine content, which is rare in other plant proteins, but its lysine content was lower than in other isolates. The sesame protein isolate displayed almost identical zeta potential profiles with its pH. The decreasing pH increased the zeta values gradually from the lowest negative value to the highest positive value. The zeta potentials of standard and defatted sesame seeds at pH 7 were –23.53 and –17.30, respectively. The hydrodynamic diameter of the sesame protein isolate (0.33 μm) was smaller than that of sesame seeds (2.64 μm) and defatted sesame seeds (3.02 μm). The sesame protein isolate had a water holding capacity of 1.26 g/g and an oil holding capacity of 3.40 g/g. Its emulsifying properties looked as follows: emulsion capacity – 51.32%, emulsion stability – 49.50%, emulsion activity index – 12.86 m2/g, and emulsion stability index – 44.96 min, respectively. These values are suitable for the sesame protein isolate and are consistent with the literature.
 The sesame protein isolate was a good source of protein (88.98%). Using sesame proteins as functional components can be an important basis for better knowledge of the relationship between electrical charge interactions in food matrices and the structure, stability, shelf life, texture, structural and functional properties of food. Research prospects include the effects of sesame protein isolates on various food systems.

Tunable Interferometric Effects between Single-Molecule Suzuki-Miyaura Cross-Couplings.

Parallel two molecular bridges loaded with a palladium catalyst were integrated into separate pairs of graphene electrodes in the same device. Based on the complete description of the one-palladium catalytic pathway by single-molecule electrical spectroscopy, this setup enables the mapping of the cross-correlation between different catalysts and demonstrates the emergent complexity in the extrapolation from single molecule to ensemble. The anticorrelation behaviors at the time scale of two individual catalysts in sufficiently close proximity were revealed in the Suzuki-Miyaura cross-coupling. Further experimental evidence demonstrates that the long-range electric dipole-dipole interaction induced by solvent leads to the destructive interferometric effect of two catalysts. In contrast, the cooperative coupling of the elementary step between two catalysts affords a local acceleration. This new form of reaction dynamics measurement via focusing on multiple molecules with single-event resolution holds great promise to build a bridge between single molecule and ensemble.

In silico analysis of the contribution of cardiomyocyte-fibroblast electromechanical interaction to the arrhythmia.

Although fibroblasts are about 5-10times smaller than cardiomyocytes, their number in the ventricle is about twice that of cardiomyocytes. The high density of fibroblasts in myocardial tissue leads to a noticeable effect of their electromechanical interaction with cardiomyocytes on the electrical and mechanical functions of the latter. Our work focuses on the analysis of the mechanisms of spontaneous electrical and mechanical activity of the fibroblast-coupled cardiomyocyte during its calcium overload, which occurs in a variety of pathologies, including acute ischemia. For this study, we developed a mathematical model of the electromechanical interaction between cardiomyocyte and fibroblasts and used it to simulate the impact of overloading cardiomyocytes. In contrast to modeling only the electrical interaction between cardiomyocyte and fibroblasts, the following new features emerge in simulations with the model that accounts for both electrical and mechanical coupling and mechano-electrical feedback loops in the interacting cells. First, the activity of mechanosensitive ion channels in the coupled fibroblasts depolarizes their resting potential. Second, this additional depolarization increases the resting potential of the coupled myocyte, thus augmenting its susceptibility to triggered activity. The triggered activity associated with the cardiomyocyte calcium overload manifests itself in the model either as early afterdepolarizations or as extrasystoles, i.e., extra action potentials and extra contractions. Analysis of the model simulations showed that mechanics contribute significantly to the proarrhythmic effects in the cardiomyocyte overloaded with calcium and coupled with fibroblasts, and that mechano-electrical feedback loops in both the cardiomyocyte and fibroblasts play a key role in this phenomenon.

A computational model to simulate spectral modulation and speech perception experiments of cochlear implant users.

Speech understanding in cochlear implant (CI) users presents large intersubject variability that may be related to different aspects of the peripheral auditory system, such as the electrode-nerve interface and neural health conditions. This variability makes it more challenging to proof differences in performance between different CI sound coding strategies in regular clinical studies, nevertheless, computational models can be helpful to assess the speech performance of CI users in an environment where all these physiological aspects can be controlled. In this study, differences in performance between three variants of the HiRes Fidelity 120 (F120) sound coding strategy are studied with a computational model. The computational model consists of (i) a processing stage with the sound coding strategy, (ii) a three-dimensional electrode-nerve interface that accounts for auditory nerve fiber (ANF) degeneration, (iii) a population of phenomenological ANF models, and (iv) a feature extractor algorithm to obtain the internal representation (IR) of the neural activity. As the back-end, the simulation framework for auditory discrimination experiments (FADE) was chosen. Two experiments relevant to speech understanding were performed: one related to spectral modulation threshold (SMT), and the other one related to speech reception threshold (SRT). These experiments included three different neural health conditions (healthy ANFs, and moderate and severe ANF degeneration). The F120 was configured to use sequential stimulation (F120-S), and simultaneous stimulation with two (F120-P) and three (F120-T) simultaneously active channels. Simultaneous stimulation causes electric interaction that smears the spectrotemporal information transmitted to the ANFs, and it has been hypothesized to lead to even worse information transmission in poor neural health conditions. In general, worse neural health conditions led to worse predicted performance; nevertheless, the detriment was small compared to clinical data. Results in SRT experiments indicated that performance with simultaneous stimulation, especially F120-T, were more affected by neural degeneration than with sequential stimulation. Results in SMT experiments showed no significant difference in performance. Although the proposed model in its current state is able to perform SMT and SRT experiments, it is not reliable to predict real CI users' performance yet. Nevertheless, improvements related to the ANF model, feature extraction, and predictor algorithm are discussed.

Bioelectricity in Plants: From So Simple a Beginning

Bioelectricity in Plants: From So Simple a Beginning

A Coordinated Multi-Energy Trading Framework for Strategic Hydrogen Provider in Electricity and Hydrogen Markets

This paper proposes a multi-energy trading framework for a hybrid-renewable-to-H2 provider (HP) to coordinate the interaction and trading of electricity and H2 while promoting the efficient accommodation of renewable energy resources (RESs). In this framework, the HP can harvest hybrid RESs for green H2 production based on electrochemical effects of biomass electrolysis, and procure stacked profits from both the electricity and H2 markets by the flexibility of electricity-H2 conversion. A Vickrey auction-based pricing mechanism is developed to determine the trading price and quantity of H2 while eliciting truthful offers and bids in a competitive H2 market. Then, a single-leader-multiple-follower Stackelberg game with an iterative solution algorithm is formulated to capture the interactions between the H2 auctioneer and hydrogen fueling stations (HFSs) for achieving the win-win goal. Furthermore, a hybrid-renewable-to-H2 production and control method is proposed for the HP to raise the production efficiency of green H2 and suppress large fluctuations in electrolysis current caused by RES uncertainties. Comparative studies have validated the superiority of the proposed methodology on economic performance and RES accommodation.

Y-Substitution effects in the crystal field of the trigonal YxRE1−xNi3Ga9 (RE = Tb, Dy, and Ho)

Multipolar ordering arising from the interplay between crystalline electric field (CEF) effects and magnetic interactions has been gaining more attention in 4f systems. In this work, we explore this possibility in the chiral magnets RENi3Ga9 (RE = Tb, Dy and Ho; x = 0.15 and 0.30) through Y-dilution. We present temperature-dependence of the M∕H curves, isothermal magnetization and heat-capacity experiments. Single crystalline samples grown by Ga self flux allow us to measure the magnetic properties for different crystallographic directions. X-ray diffraction patterns analyzed by Rietveld method indicate that all samples crystallize in a trigonal ErNi3Al9-type structure with space group R32. Our results are consistent with an antiferromagnetic order with transition temperatures TN< 20 K for all the studied samples, which decrease gradually with Y-substitution. By using a mean field model including anisotropic near- and next-near-neighbors magnetic interactions and the trigonal CEF Hamiltonian, we are able to study in detail the evolution of the crystal-field scheme and magnetic couplings for these compounds. We show that the spatial charge distribution between the compounds are in agreement, increasing the confidence of the obtained CEF schemes. Finally, we compare our fittings with disorder simulations assuming that CEF effects should not evolve as a function of Y-substitution. Our results show that only disorder effects do not fully describe the experimental data, which may indicate that quadrupolar degrees of freedom indeed have a role in the magnetic properties of this family.