Electric Precipitation Research Articles

A novel electric spark precipitation and electrospinning strategy to prepare cerium hydroxide nanocomposite for phosphate uptake from aqueous solutions

Phosphorus is a main cause of eutrophication in water bodies, the use of adsorbents to reduce phosphate concentration in water is considered an effective way to combat eutrophication. Herein, a new and effective strategy for phosphorus removal with a PAN based cerium hydroxide nanocomposite (CHP) is shown, we combined electrospinning and spark ablation techniques, where an electrospun fiber membrane polyacrylonitrile (PAN) was used as a carrier, spark ablation produced clean nano-cerium aerosol embedded in it as the active ingredient, and a combined hydrothermal method to develop PAN based cerium hydroxide nanocomposite (CHP), the crystal size of ceria nanoparticles was 120–210 nm. CHP can capture phosphate selectively with a maximum adsorption capacity of 86.7 mg·P/g, which is higher than that for most cerium-based adsorbents and is easily separated from the liquid with high efficiency and economy. The adsorption mechanism showed that CeO2 plays an important role in phosphorus adsorption through oxidation, reduction, and ligand exchange. Compared to mesoporous structures, fibrous structures are more favorable for reducing the aggregation of nanoparticles (NPs) and adsorption of large phosphate species. The spark ablation method immobilized active cerium dioxide NPs very stably on the fiber with high efficiency and limited environmental impact. In conclusion, our results have promising applications for lake eutrophication treatment.

Examining Microdroplet Characteristics of Electrospray Electric Precipitation for Direct and Indirect Voltage Application Methods

Dust and fine dust exist in various forms and can lead to various problems such as dust explosion and air pollution. To reduce them, recently, research on electrospray electric precipitation, among various dust collection methods, has been actively conducted. In this study, comparative analysis experiments were performed on microdroplet generation characteristics for direct and indirect charging methods of electrospray electric precipitation. A visualization device was fabricated to generate microdroplets, and microdroplets were photographed with a high-magnification camera according to each charging method. The size and number of microdroplets were then analyzed via ImageJ software.

Controlling the Thermal Stability, Threshold Voltage, and Thermoelectric Properties of Cuprous Sulfide Thermoelectrics.

Cu-ion liquid-like copper sulfide materials have excellent thermoelectric properties, while their applications are limited by their high-temperature decomposition and electric field-driven Cu precipitation issues. In particular, high thermoelectric properties and electric field-driven degradation are difficult to reconcile because liquid-like Cu ions are dominant in low κ and high ZT, while they cause electric field-driven degradation. Here, we control the sintering current and duration time to remove the Cu1.8S phase, thereby inhibiting the thermal decomposition of the copper sulfide samples, and introduce the Fe element into the sample matrix to improve its resistance to electric field-driven degradation. We reveal that the kinetic process of Cu1.8S phase decomposition can be suppressed by increasing the relative density of the sample or covering a layer of dense coating/film on the surface of the sample. However, as long as the Cu1.8S phase is present in the sample, it cannot maintain thermal stability above 450 °C. Furthermore, we find that the Fe element forms a nanogrid spinodal decomposition structure in the sample matrix, which acts as a barrier wall to prevent the long-range diffusion of liquid-like Cu ions and inhibit the electric field-driven degradation. The freely movable liquid-like Cu ions in the grid maintain a strong scattering of phonons in a short range, so the sample possesses low κ and high ZT. Then, a strategy to unify the high thermal decomposition temperature, high threshold voltage, and high thermoelectric performance of copper sulfide thermoelectric materials is proposed: transforming the Cu1.8S phase and introducing a liquid-like Cu ion migration barrier.

Electric current-induced precipitation hardening in advanced high-strength steel

Effect of electric current on precipitation hardening for advanced high-strength steel is investigated based on mechanical testing and microscopic observation. Complex-phase steel containing nano-sized Nb-bearing carbides was used. By comparing the flow stress between uniaxial tension with applied electric current (pulsed tension) and without electric current (nonpulsed tension) at various elevated temperatures, the influence of electric current on precipitation hardening was confirmed. A higher values of Vickers hardness and full-width-at-half-maximum were obtained in the pulsed tensile specimen compared to the identically heat treated specimen after the same deformation. Small angle neutron scattering analysis showed that the volume fraction and mean diameter of newly formed precipitates in the pulsed tensile specimen were higher and larger than those in the induction heat treated specimen, respectively. It clearly shows that additional precipitation hardening could be induced by the athermal effect of electric current, which is distinct from the thermal effect of Joule heating.

The LAI Coupling Associated with the M6 Luxian Earthquake in China on 16 September 2021

Periodic signals replaced noise that was found in continuous seismic data, particularly in the nighttime, from the broadband seismometer at the MVP-LAI (monitoring vibrations and perturbations in the lithosphere, atmosphere and ionosphere) system before the occurrence of the Luxian earthquake on 16 September 2021. A short distance of ~150 km between the MVP-LAI system and the epicenter of the Luxian earthquake suggests the periodic singles as promising seismo-phenomena, due to that the radius of the earthquake preparation zone is ~380 km for an M6 event. Integration of geophysical parameters, including atmospheric pressure, vertical electric field, radon concentration, groundwater level and precipitation, at the MVP-LAI system provides an excellent opportunity for studying the seismo-LAI coupling associated with the Luxian earthquake. Analytical results show that ground vibrations, atmospheric pressure and total electron content varied from ~10−3 to ~10−2 Hz before the Luxian earthquake. The seismo-LAI coupling in the relatively low frequency band (~10−3 Hz) can be referred to as the acoustic-gravity waves triggered by the amplified ground vibrations. In contrast, the seismo-LAI coupling in a relatively high frequency band (~10−2 Hz) would be caused by micro-cracks and/or the high-mode natural frequency that further drives changes of TEC due to the atmospheric resonance.

Time-dependent responses of the neutral mass density to fixed magnetospheric energy inputs into the cusp region in the thermosphere during a period of large IMF BY: a high-resolution two-dimensional local modeling

Thermospheric mass density values around the 400-km altitude in the cusp can be significantly enhanced as compared to regions around the cusp. To gain insights into the extent to which the magnitude of the cusp mass density enhancements can be explained by the static distributions of moderate electric field and electron precipitation typical for a period of large IMF BY, we employed a high-resolution two-dimensional local model that can represent the plasma features that are characteristic of the cusp: azimuthal ion flow and low-energy electron precipitation. We also calculated the thermospheric dynamics with and without neutral–ion drag. We found that in the calculation with this drag the obtained mass density enhancement is 10% at most, indicating that the thermospheric dynamics imposing the moderate static electric field and electron precipitation can only explain about one-third of the typical magnitude of cusp thermospheric mass density, i.e., 33%. We also found that in the calculation without neutral–ion drag the magnitude of the mass density enhancement is slightly larger than the one with the neutral–ion drag. To explain the average magnitude of the cusp mass density enhancements completely, other energy inputs such as Alfvén waves, in addition to the static distributions of electric field and electron precipitation, are needed.Graphical

Виготовлення електрошлаковим наплавленням ударної частини молотків механізму струшування електрофільтрів

The expediency and relevance of the development of technological solutions that make it possible to increase the efficiency of electric precipitation filters, which are the main gas cleaning equipment at thermal power plants, metallurgical and cement industries, have been considered. It is recommended to improve the operation of the shake mechanism of the electrical precipitator by forming the impact part of the hammer with a material resistant to plastic deformation under impact loads and provides a minimum and constant area of impact contact of the hammer with the shaking anvil beam throughout the life cycle. Review and analysis of publications in the field of surfacing revealed the lack of data on the properties of the proposed material deposited by electroslag method, as well as its use in the impact mechanisms of electrical precipitators. The impact part of the hammer was made of the proposed material by electroslag surfacing in a special detachable copper water-cooled mold with a powder electrode. The structure and properties of the metal of the hardened part of the hammer have been studied. As a result, it has been found that the chemical composition of the metal of the deposited impact part of the hammer is close to the composition of the metal deposited with the OZN-300M electrodes with a low content of sulfur and phosphorus; this being due to the effect of refining in electroslag remelting. The surfacing process provides the formation of a tight monolithic, homogeneous dispersed and defect-free structure characteristic of cast electroslag metal. In the cast metal, the presence of non-metallic inclusions of predominantly globular shape with a characteristic average size of 2.5-4.5 μm in the form of oxides and sulfides with a volume percentage (0.60-0.70)×10-2 and (0.51-0.60)×10-2, respectively has been revealed

Small‐Scale and Mesoscale Variabilities in the Electric Field and Particle Precipitation and Their Impacts on Joule Heating

AbstractIn this study, the electric field and the particle precipitation at different spatial scale sizes have been investigated by utilizing the Dynamic Explorer 2 satellite data set, focusing on conditions of moderately strong southward interplanetary magnetic field. Dynamic Explorer 2 data from the period between 1981 and 1983, from all universal times, seasons, and both hemispheres, have been processed and binned over geomagnetic latitude and local time. It is found that, as compared with the large‐scale (>500 km) average electric field and particle precipitation, the variabilities (i.e., departures from the large‐scale average) of electric field and particle precipitation are not negligible. Moreover, the electric field variability tends to be anticorrelated with the particle precipitation variability in the auroral regions on small scale and mesoscale (<500 km). The impacts associated with the small‐scale and mesoscale electric field and particle precipitation variabilities on Joule heating have also been addressed in this study by using the Global Ionosphere and Thermosphere Model. It is found that although Joule heating can be significantly enhanced by the small‐scale and mesoscale electric field variabilities (~27% globally), the corresponding change in the particle precipitation tends to depress such enhancement (−5% globally), which is not negligible on the dusk side (up to −17.5% locally). It is the first time that the correlation between electric field and particle precipitation variabilities on small scale and mesoscale has been quantified. Furthermore, the impact on Joule heating associated with the correlation between the small‐scale and mesoscale electric field and particle precipitation variabilities has been evaluated unprecedentedly in a general circulation model.

High-gradient ferromagnetic matrices for purification of wastewaters by the method of magnitoelectrolysis

The paper has investigated the efficiency of high-gradient ferromagnetic matrices of a magnetic filter obtained by the method of magnetoelectrolysis at different parameters of the process using a magnetically controlled biosorbent based on the yeast S. cerevisiae and nanomagnetite. The paper has studied the morphology of matrices at different parameters of electric precipitation such as the value of the external magnetic field and magnetization conditions of the matrix base. We have measured quantitative indices of the operation of every type of matrices: maximum efficiency of extraction of the magnetically controlled biosorbent of ions of metals from wastewaters and the optimal time of the operation of manufactured matrices.

Effective and Low-cost Purification of Lysozyme by Combination of Conventional Processes

In this study, a simple method to purify lysozyme was introduced, based on combination of conventional processes, including thermal treatment is electric point precipitation and gel chromatography. The sample was purified well by compared with lysozyme standard and no other proteins appeared in Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE).

Growth Mechanism, Structural and Optical Properties of ZnO Nanoparticles

This paper using an electric field-assisted direct precipitation method synthesize the ZnO nanosheets with zinc nitrate hexahydrate and sodium carbonate. The synthesis processes with and without an electric field were compared. The morphology of the ZnO nanosheets was investigated by scanning electron microscopy (SEM) measurements. The SEM results show that the application of an electric field caused the morphology transformation from flake-like to flower-like. It was found that an electric field had an effect on the crystal structure，the particle size and morphology. The photoluminescence spectrum of the synthesized ZnO nanosheets shows a strong ultraviolet emission at 249 nm. In addition，the formation mechanism of the ZnO nanosheets is discussed.

Synthesis of Spherical Zinc Oxide Micro-Flower via an Electric Field-Assisted Homogeneous Precipitation Method

This paper presents the experimental results on electric field-assisted synthesis of spherical Zinc Oxide (ZnO) micro-flower in an homogeneous precipitation method. The synthesis processes with and without an electric field were compared. The products were characterized via SEM, XRD, TGA and FT-IR spectrum. The results show that the spherical ZnO micro-flower composed of ZnO single crystalline nanoparticles have thickness of about 10nm, width of about 50nm.The SEM results show that the application of an electric field caused the morphology transformation from flake-like to flower-like. It was found that an electric field had an effect on the crystal structure,the particle size and morphology.

Ionospheric disturbances generated by different natural processes and by human activity in Earth plasma environment

The magnetosphere-ionosphere-thermosphere subsystem is strongly coupled via the electric field, particle precipitation, heat flows and small scale interaction. Satellites in situ measurements and ground based complex diagnostics can provide comprehensive coverage of both time and geomagnetic place effects. Human activity also can perturb Earth s environment, but few are connected with controlled experiments in the ionosphere and are transient. Most of them are related to industrial activity and have increased in recent years. The most important power sources are broadcasting transmitters, power stations, power lines and heavy industry. At ionospheric altitude some disturbances and physical processes are related to seismic activity, thunderstorm activity and some global changes in the Earth environment such as ozone holes. Various natural and artificial indicators can affect satellite telecommunication quality. The aim of this presentation is to report progress in understanding the physical processes in the ionosphere described above and to assess the application of these considerations to the study of plasma effects on Earth-space and satellite-to-satellite communication.

Response of the ionosphere–thermosphere system to magnetospheric processes

The magnetosphere–ionosphere–thermosphere system at high latitudes is strongly coupled via electric fields, particle precipitation, plasma and neutral outflows, and field-aligned currents. Although the climatology of the coupled system is fairly well established, our understanding of the variability of the disturbed state (weather) is rudimentary. This variability is associated with magnetic storms and substorms, nonlinear processes that operate over a range of spatial scales, time delays, and feedback mechanisms between the different domains. The variability and resultant structure of the ionosphere can appear in the form of propagating plasma patches and polar wind jets, pulsing ion and neutral polar winds, auroral and boundary blobs, and ionization channels associated with polar cap arcs, discrete auroral arcs, and storm-enhanced densities (SEDs). The variability and structure of the thermosphere can appear in the form of propagating atmospheric holes, neutral gas fountains, neutral density patches, and transient neutral jets. In addition, during periods of enhanced plasma convection, the neutral winds can become supersonic in relatively narrow regions of the polar cap. The spatial structure in the ionosphere–thermosphere system not only affects the local environment, but the cumulative effect of multiple structures may affect the global circulation and energy balance. A focused topical review of recent results in our modeling the variability and structure of the high-latitude ionosphere–thermosphere system is presented. This review was given at the Greenland Space Science Symposium (May 2007).

Possible reasons for underestimating Joule heating in global models: E field variability, spatial resolution, and vertical velocity

It is important to understand Joule heating because it can significantly change the temperature structure, atmosphere composition, and electron density and hence influences satellite drag. It is thought that many coupled ionosphere‐thermosphere models underestimate Joule heating because the spatial and temporal variability of the ionospheric electric field is not totally captured within global models. Using the Global Ionosphere Thermosphere Model (GITM), we explore the effect of the electric field temporal variability, model resolution, and vertical velocity differences between ion and neutral flows on Joule heating in a self‐consistent thermosphere/ionosphere system. First, the response of Joule heating to a step change in the externally driven electric field has been studied. While Joule heating is strongly affected by the convection electric field, both neutral winds and electron densities can significantly alter the spatial distribution of the Joule heating. Owing to the ramping up of neutral winds, there is a temporal variation of the Joule heating energy deposition rate when the electric field is constant. Second, we compare the calculated neutral gas heating rates when GITM is run with three different temporal variations of the electric fields, having the same temporally averaged electric field () but different standard deviations (σE). The neutral gas heating rate increases with the electric field temporal variability, and due to the feedback of the neutral winds and electron densities, the percentage increase is different from σE2/2, which is normally used to describe the effect of electric field temporal variability on the Joule heating. Third, comparison of the neutral gas heating rate with different model resolutions shows that at 200 km altitude, the polar average neutral gas heating rate increases by 20% when the latitudinal resolution increases from 5° to 1.25°. This is due to the model's ability to better capture small‐scale features in the electric field and particle precipitation. Last, inclusion of the vertical velocity difference (which is neglected in many models) is less significant than the other two factors and appears to be negligible at high latitudes. While the magnitude of the neutral gas heating rate at middle and low latitudes is smaller than that at high latitudes, the relative importance of the vertical velocity difference is larger, and the contribution can reach 15% of the averaged Joule heating at middle and low latitudes.

Kinematics of charged nanometric particles in silent discharges

We use 1 mm plane to plane configurations, with or without dielectric barriers, on metallic electrodes to investigate the ac electric precipitation of charged submicronic particles of controlled electrical mobility injected in a laminar flow. The collection efficiency is calculated from concentration measurements for different voltages. Below the air ionization threshold, experimental and theoretical collection efficiencies are consistent. Above the air ionization threshold, the current and collection efficiency increase with frequency and voltage related to the number of microdischarges per second and per unit surface area. This study intends to study the influence of surface polarization due to the development of microdischarges on the collection of charged particles. Comparison between the theory of collection in a homogeneous ac field without microdischarge, on the one hand, and measured collection efficiency with microdischarges, on the other hand, proves that surface polarization by microdischarges does not improve the collection efficiency, but enables either an increase of charge by ion repulsion from the surface, whatever the frequency is, or an improved mixing at 60 kHz.

Surface precipitation electric current produced by convective rains during the Mesoscale Alpine Program

This paper presents data from measurements of electric field, precipitation current density, and rainfall parameters performed during the Mesoscale Alpine Program experiment in northern Italy during autumn 1999. Several days of the period provided substantially charged rainfall of both polarities. The average proportions of each polarity are close, but the negative one is slightly larger (54%). Three Doppler radars provided a description of the cells' development and dynamics. A case of a deeply convective cell occurred on 17 September 1999. In this case, the precipitation current density is first positive, reaches more than 100 nA m−2, and changes its polarity when the rainfall is maximum with a value close to 200 mm h−1. We also consider several shallow convective cells passing over the experimental site on 3 October. Two cells among a set of eight did not produce electrical parameter variations although they displayed development and radar reflectivity structure similar to that of the others. The dynamical study shows that the vertical velocity (averaged over 1 km × 1 km mesh) was weaker within these two cells with a value of only 0.5 m s−1 while it reached 1.5 m s−1 within the other cells. Both charge polarities were observed on the rain produced by electrified cells, first the negative one and then the positive one. A very tight correlation between surface electric field and precipitation current is observed out at the surface, displaying the mirror image effect. The ground electric field is due to the cloud charge, in contrast with that carried down to the ground by the rainfall. In order to reproduce the field evolution created by the cell passage, we test different models of charge distribution. A model including a horizontal distribution is found to provide a field evolution in best agreement with the observations. According to this model the net charge of the cloud above the site is chronologically positive and negative, which can be the result of the evacuation of an opposite charge by the rain.

Characterization of mare caseins. Identification of $\alpha_{{\bf S1}}$- and $\alpha_{{\bf S2}}$- caseins

Whole mare (Mongolian and French breeds) casein was obtained from skim milk by iso- electric precipitation (pH 4.6) at 22 °C. In another series of experiments, equine caseins were frac- tionated after isoelectric precipitation at 4 °C, according to their sensitivity to temperature, on one hand, the pH of the resulting pellet was adjusted to 6.5 before centrifugation (45 000 g for 30 min) at 4 °C; on the resulting casein fraction which precipitated was named the cold precipitated (CP) fraction. On the other hand, the supernatant obtained from the centrifugation of skim milk at pH 4.6 and 4 °C was warmed to 30 °C before being centrifuged at 30 °C, 45 000 g, for 30 min. The resulting casein frac- tion which precipitated was named the thermally precipitated (TP) fraction. Equine caseins were then purified by high resolution gel chromatography on an anion-exchange column followed by reversed phase-high performance liquid chromatography. The casein fractions were analyzed by urea- and SDS-polyacrylamide gel electrophoresis, their amino acid compositions were determined and their first 15 N-terminal amino acids were sequenced. This analysis showed the presence of α s - like caseins isolated from the CP fraction. α s1 -Like-casein showed 4 major double bands by elec- trofocusing with a pI range of 4.3-4.8. In the same conditions, α s2 -like casein showed 2 major bands with a pI range of 4.3-5.1. The TP fraction revealed the existence in equine milk of 6 subfractions of β-like caseins, occurring in the following ratios: 1:5:18:20:15:10, differing at least in their degree of phosphorylation (as shown also by the action of acid phosphatase). Since no evidence of the presence of κ-casein was found in equine milk, it is proposed that part of its functions in the milk of the Equidae could be assumed by the population of less phosphorylated β-caseins. mare milk / α s1 -casein / α s2 -casein / β-casein

Electric pulse-induced precipitation of biological macromolecules in electroporation

We found that electric discharge through solution of biological macromolecules (DNA, RNA and proteins) causes precipitation of significant portions of these macromolecules. This precipitation is a consequence of the interaction of biological macromolecules with the metal ions solubilized from the anode plate by the electric pulse, and occurs in both absence and presence of the cells in poration medium. Precipitated fractions of macromolecules sediments at the centrifugation speed used to pellet eukaryotic cells and does not dissolve when washed with buffer. Our data indicate a complication of the direct evaluation of electroporation efficiency based on the assumption that electroporated biological macromolecules which remain associated with the cells after several washes, are successfully electroinjected into the cytoplasm of cells.

Ionospheric storm simulations driven by magnetospheric MHD and by empirical models with data comparisons

The results of two ionospheric simulations are compared with each other and with ionospheric observations of the southern hemisphere for the magnetic cloud passage event of January 14, 1988. For most of the event one simulation agrees with observations, while the other does not. Electric fields and electron precipitation patterns generated by a magnetospheric MHD model are used as inputs to a physical model of the ionosphere in the successful simulation, while empirical electric fields and electron precipitation are used as the inputs for the second simulation. In spite of ionospheric summer conditions a large and deep polar hole is developed. This is seen in the in situ plasma observations made by the DMSP‐F8 satellite. The hole is surprisingly present during both northward and southward IMF conditions. It is deepest for the storm phase of the southward IMF period. A well‐defined tongue of ionization is formed during this period. These features have been reproduced by the TDIM‐MHD simulation and to a lesser extent by the TDIM‐empirical simulation. However, the model simulations have not been able to generate a storm enhanced density where one was observed by DMSP‐F8 during the initial phase of the storm. The differences between the two F region ionospheric simulations are attributed to differences in the magnetospheric electric fields and precipitation patterns used as inputs. This study provides a unique first simulation of the ionosphere's response to self‐consistent electric field and auroral precipitation patterns over a 24‐hour period that leads into a major geomagnetic storm.