Discharge Activity Research Articles

Reducing the Internal Stress of Fe-Ni Magnetic Film Using the Electrochemical Method

Soft magnetic materials are important functional materials in the electrical engineering, radio, and high-tech fields, but thin and brittle flakes present challenges to the manufacturing industry. In this study, the effect and mechanism of saccharin sodium in reducing the internal stress of Fe-Ni magnetic films were analyzed. The effects of the pH value, temperature, and the concentration of saccharin sodium on the deposition process of Fe-Ni alloys were investigated. The polarization curve of the Fe-Ni alloy deposition process was measured by using a multifunctional electrochemical workstation, and the morphology and crystal structure were measured by a scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that saccharin sodium significantly reduced the stress of the iron-nickel magnetic film; the mechanism through which the internal stress was reduced is analyzed in this paper. Briefly, the Fe2+ and the amino group of saccharin sodium synthesized a metal complex with positive charge on the surface of the electrode, which prevented the hydrogen ions from approaching the cathode and increased the discharge activation energy of the hydrogen ion, which reduced the hydrogen evolution and improved the internal stress of the coating. This research will help to solve the challenges of producing magnetic film, and promotes the application of new stress-reducing agents.

Discharge Rehabilitation Measures Predict Activity Limitations in Patients With Stroke 6 Months After Inpatient Rehabilitation.

The aim of this study was to identify rehabilitation measures at discharge from acute inpatient stroke rehabilitation that predict activity limitations at 6 mos postdischarge. This is a retrospective analysis of a prospective, longitudinal, observational cohort study. It was conducted in an acute inpatient rehabilitation unit at an urban, academic medical center. Activity limitations in patients ( N = 141) with stroke of mild-moderate severity were assessed with the activity measure for post-acute care at inpatient stroke rehabilitation discharge and 6-mo follow-up. Rehabilitation measures at discharge were investigated as predictors for activity limitations at 6 mos. Measures of balance (Berg Balance Scale), functional limitations in motor-based activities (functional independence measure-motor subscore), and motor impairment (motricity index), in addition to discharge activities measure for post-acute care scores, strongly predicted activity limitations in basic mobility and daily activities at 6 mos (51% and 41% variance explained, respectively). Functional limitations in cognition (functional independence measure-cognitive subscore) and executive function impairment (Trail Making Test-part B), in addition to the discharge activities measure for post-acute care score, modestly predicted limitations in cognitively based daily activities at 6 mos (12% of variance). Standardized rehabilitation measures at inpatient stroke rehabilitation discharge can predict future activity limitations, which may improve prediction of outcome post-stroke and aid in postdischarge treatment planning.

Fluorescent fiber-based identification of incipient discharges in liquid nitrogen

Identification of incipient discharges is a major challenge in liquid nitrogenbased super-conducting power apparatus. In the present study, a variety of fluorescent fibers with different absorption/emission characteristics were used for the identification of corona and surface discharges, and we find that a particular type of fluorescent fiber is more sensitive to identify discharges in liquid nitrogen insulation than the UHF technique. Enhancement in the magnitude of fluorescent signal/UHF signal is observed for an increase in applied voltage beyond the corona inception voltage (CIV). Also, it is observed that while reducing the applied voltage, the corona activity quenches at a much lower voltage than the inception voltage. No characteristic variation in rise time or the fall time of the fluorescent signal is observed on corona inception and due to discharges at higher voltages. The corona inception voltage is least for AC voltage conditions, and slightly higher inception voltage is observed for positive DC and negative DC voltage conditions. Different weight percentages of MgO doping in GFRP nanocomposites are prepared and used in the surface discharge studies. It is observed that the 3 wt% sample exhibits enhanced surface discharge inception voltage (SDIV) compared to samples with other doping concentrations and that the inception voltage is lower for AC voltage when compared with the DC voltage conditions. The characteristic spectral content of the fluorescent signal due to corona and surface discharge activity is observed up to 3 MHz. A phase-resolved partial discharge (PRPD) analysis was also carried out to identify corona and surface discharge activity using fluorescent fiber sensor and with a UHF sensor. From the PRPD studies, it is observed that the corona discharge occurs near the peak magnitude whereas surface discharge is observed at the rising part of AC voltage.

Detection of Electrical Tree Formation in XLPE Insulation through Applying Disturbed DC Waveforms

Initiation and growth of electrical trees can be linked to the development of partial discharge (PD) activity within an insulation system. We present in this paper changes in PD characteristics that appear during the electrical tree growth in a crosslinked polyethylene (XLPE) based insulation at different stages of its degradation. A DC voltage with superimposed high frequency component is applied to the material specimens for the detection and characterization of PD traces observed during the degradation. The method is flexible and offers a possibility to vary DC voltage level independently of the superimposed disturbance, its frequency and rise time, including rapid voltage steps. It also enables to create a phase-locked phase-resolved PD pattern (PRPD) facilitating various analyses of the characteristics. It is postulated that measurements of the changes in PD characteristics found under such excitations can be used for performing diagnostics and prognostics of material condition. This approach also implies new possibilities to evaluate different material concepts.

Enhancement of discharge performance for aqueous Mg-air batteries in 2,6-dihydroxybenzoate-containing electrolyte

In this work, 2,6-dihydroxytbenzoate (2,6-DHB) is evaluated as an efficient electrolyte additive for aqueous Mg-air batteries based on diverse metallic Mg anodes. EIS measurements amid intermittent discharge and real-time hydrogen evolution measurements during discharge were applied to clarify the effective mechanism. The dependence of working mechanism on 2,6-DHB concentration was investigated for a newly developed Mg-0.15Ca anode. The results reveal that sufficient amount of 2,6-DHB simultaneously improves the discharge activity and inhibits the self-discharge of Mg-0.15Ca anode, leading to negative average potential and high anodic utilization efficiency. Accordingly, 0.2 M 2,6-DHB is determined as the most suitable electrolyte concentration and applied during Mg-air battery tests based on diverse commercial Mg anodes (pure Mg, Mg-0.15Ca, AZ31 and AM50). The results demonstrate that 2,6-DHB efficiently improves the discharge performance of Mg-air batteries with different Mg anodes.

Effect of Ce content on performance of AZ31 magnesium alloy anode in air battery

In this work, five AZ31-xCe magnesium alloy anode materials were prepared, and their microstructure, electrochemical properties and discharge properties were studied to reveal the effect of Ce content on the casting anode of magnesium air battery. The introduction of the Ce element can refine the grain and purify the α-Mg matrix. AZ31–1Ce magnesium alloy has the best corrosion resistance, and the activity of magnesium alloy enhances with the increase of Ce content. Compared with AZ31 magnesium alloy, AZ31-xCe magnesium alloy has higher discharge activity, which is due to the introduction of Ce element to purify the magnesium alloy, and the Al4Ce phase can promote the uniform dissolution of Mg matrix. When the discharge current density is 10 mA cm−2 the AZ31–4Ce anode shows the highest energy density of 1552.370 mWh g−1 and the best specific capacity of 1282.051 mAh g−1 which are 46.05% and 29.901% higher than the AZ31 anode. Compared with AZ31 magnesium alloy, the anode of AZ31–4Ce magnesium alloy has a smoother discharge surface morphology, which is beneficial to the desquamation of the discharge products.

From decimeter-scale elevated ionic conductivity regions in the cloud to lightning initiation

In this work, we represent the lightning initiation scenario as a sequence of two transitions of discharge activity to progressively larger spatial scales: the first one is from small-scale avalanches to intermediate-scale streamers; and the second one is from streamers to the lightning seed. We postulate the existence of ion production centers in the cloud, whose occurrence is caused by electric field bursts accompanying hydrometeor collisions (or near collisions) in the turbulent thundercloud environment. When a new ion production center is created inside (fully or partially) the residual ion spot left behind by a previously established center, there is a cumulative effect in the increasing of ion concentration. As a result, the essentially non-conducting thundercloud becomes seeded by elevated ion-conductivity regions (EICRs) with spatial extent of 0.1–1 m and a lifetime of 1–10 s. The electric field on the surface of an EICR (due to its conductivity being at least 4 orders of magnitude higher than ambient) is a factor of 3 or more higher than ambient. For a maximum ambient electric field of 100 kV/m typically measured in thunderclouds, such field enhancement is sufficient for initiation of positive streamers and their propagation over distances of the order of decimeters, and this will be happening naturally, without any external agents (e.g., superenergetic cosmic ray particles) or extraordinary in-cloud conditions, such as very high potential differences or very large hydrometeors. Provided that each EICR generates at least one streamer during its lifetime, the streamers will form a 3D network, some parts of which will contain hot channel segments created via the cumulative heating and/or thermal-ionizational instability. These hot channel segments will polarize, interact with each other, and cluster, forming longer conducting structures in the cloud. When the ambient potential difference bridged by such a conducting structure exceeds 3 MV, we assume that the lightning seed, capable of self-sustained bidirectional extension, is formed.

Effect of Ga on microstructure and electrochemical performance of Al–0.4Mg–0.05Sn–0.03Hg alloy as anode for Al–air batteries

The effects of 0.01 wt.% Ga on microstructure and electrochemical performance of Al–0.4Mg–0.05Sn– 0.03Hg anodes in NaOH solutions were investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy, and galvanostatic discharge tests were used to assess the electrochemical performance of the Al–Mg–Sn–Hg–Ga anodes. The results show that the addition of 0.01 wt.% Ga in Al–0.4Mg–0.05Sn–0.03Hg anode enhances its corrosion resistance and discharge activity. It is benefited from the refined second phases and homogenous microstructure of Al–Mg–Sn–Hg–Ga anode, which restrains the local crystallographic corrosion and chunk effect. Compared with Al–Mg–Sn–Hg anode, the corrosion current density and the mass loss rate of Al–Mg–Sn–Hg–Ga anode decrease by 57% and 93%, respectively. When discharging at the current density of 20 mA/cm2, the discharge voltage, current efficiency and specific capacity of the single Al–air battery with Al–0.4Mg–0.05Sn–0.03Hg–0.01Ga anode are 1.46 V, 33.1%, and 1019.2 A·h·kg−1, respectively. The activation mechanism of Ga on Al–Mg–Sn–Hg–Ga anode materials was also discussed.

Effects of seasonal changes and environmental factors on bioindicator bacteria levels in Çardak Lagoon, Çanakkale Strait, Turkey

Abstract Çardak Lagoon is one of the most important marine environments in the Turkish Strait system, which is home to a variety of organisms. The lagoon is currently under stress and faces the risk of heavy pollution. For this reason, the present state of the lagoon was monitored in this study. During sampling from October 2018 to June 2019, the levels of indicator microorganisms fluctuated up to 4.04 Log10 cfu 100 ml−1 and their presence was found to be higher in warmer seasons. The highest positive correlations were observed for total coliform levels with salinity and chemical oxygen demand, whereas the highest negative correlations were found between the levels of fecal coliforms, pH and temperature. E. coli and fecal streptococci showed moderate correlations with the environmental factors in all seasons. Although nitrite and nitrate (NO2 + NO3) were not significantly correlated with bacteria levels, they were present at elevated levels. Çardak Lagoon showed the lowest microbiological and chemical quality in the summer season, and this situation continued into the autumn season as a possible result of increased wastewater discharge and human activities. The lagoon should therefore be monitored regularly and precautions should be taken to prevent severe ecological deterioration.

Factors driving the abundance and distribution of microplastics on sandy beaches in a Southwest Atlantic seaside resort

Microplastics are currently considered widespread marine pollutants, accumulating in sediments and shorelines around the world. Spatial distribution of microplastics in marine sediments is consequence of a combination of multiple factors (naturals and anthropics). We evaluated the drivers' factors of the abundance and distribution of two microplastics morphotypes (fibers and fragments) in surface sediments (5 cm deep) on SW Atlantic beaches with different plastics waste contribution along the coastline. Beach geomorphology, sediment grain size, distance to the urban area, continental waters discharge and human activities were the analyzed factors. Fibers abundance was significantly highest in pocket beaches, moderately exposed and closest to the urban center, while the fragments abundance was highest in beaches with stormwater outfall. The fine sand and the high recreational level were also factors driving the abundance of both morphotypes. Therefore, plastic morphotype and abundance vary according to the determining factors.

Electrical properties and synaptic transmission in mouse intracardiac ganglion neurons in situ.

The intrinsic cardiac nervous system represents the final site of signal integration for neurotransmission to the myocardium to enable local control of cardiac performance. The electrophysiological characteristics and ganglionic transmission of adult mouse intrinsic cardiac ganglion (ICG) neurons were investigated using a whole‐mount ganglion preparation of the excised right atrial ganglion plexus and intracellular microelectrode recording techniques. The passive and active electrical properties of ICG neurons and synaptic transmission including synaptic response strength and efficacy as a function of stimulation frequency were examined. The resting membrane potential and input resistance of ICG neurons were −47.9 ± 4.0 mV and 197.2 ± 81.5 MΩ, respectively. All neurons had somatic action potentials with overshoots of >+15 mV and after‐hyperpolarizations having an average of 10 mV amplitude and ~45 ms half duration. Phasic discharge activities were recorded from the majority of neurons studied and several types of excitatory synaptic responses were recorded following inputs from the vagus or interganglionic nerve trunk(s). Most postganglionic neurons (>75%) received a strong, suprathreshold synaptic input and reliably followed high‐frequency repetitive nerve stimulation up to at least 50 Hz. Nerve‐evoked synaptic transmission was blocked by extracellular Cd2+, ω‐conotoxin CVIE, or α‐conotoxin RegIIA, a selective α3‐containing nicotinic acetylcholine receptor antagonist. Synaptic transmission and the electrical properties of murine ICG neurons contribute to the pattern of discharge which regulates chronotropic, dromotropic, and inotropic elements of cardiac function.

Modelling of partial discharge pulse propagation in transformer windings using multi conductor transmission line modelling scheme

Power transformers are considered as an essential component in the electric power systems. They are placed in services in different circumstances like electrical, environmental and mechanical stresses, and through the progress of operation it can affect with various threats and hazards. Transformer failure should be diagnosed earlier in order to avoid its unsafe and unstable operation. The main reason for failure of insulation in power transformer is due to partial discharges. The partial discharge activity occurring in the transformer have to be identified earlier, afore it progresses into a complete discharge, otherwise it results in the maintenance of the device and causes loss of economic cost to the utilities. In this paper, multi conductor transmission line theory is used for the modelling of transformer windings and the partial discharge pulse propagation through the winding is simulated in the MATLAB Simulink. The effect of partial discharge on the windings are also discussed.

Improved discharge performance of equal-channel-angular-pressed AZ61-In alloys as anodes for seawater-activated batteries

Novel Mg alloy anodes with high efficiency have great potential in seawater batteries for marine explorations. This work investigated the effect of indium addition and equal-channel angular pressing on discharge performance and electrochemical properties of commercial AZ61 alloy via hydrogen evolution, weight-loss test, electrochemical and discharge measurements in 3.5 wt% NaCl. The results indicated that indium addition promoted the formation of second phases due to the segregation effect. The pressing process effectively refined the grains and contributed to the uniform grain distribution, which was beneficial to the discharge performance and corrosion resistance of the Mg anodes. The pressed AZ61-In exhibited improved discharge activity and anode utilization compared to as-cast AZ61 and AZ61-In alloys.

Characterization of Partial Discharge Activities in WBG Power Converters under Low-Pressure Condition

Many sectors, such as transportation systems, are undergoing rapid electrification due to the need for the mitigation of CO2 emissions. To ensure safe and reliable operation, the electrical equipment must be able to work under various environmental conditions. At high altitudes, the low pressure can adversely affect the health of insulating materials of electrical systems in electric aircraft. A well-known, primary aging mechanism in dielectrics is partial discharge (PD). This study targets internal PD evaluation in an insulated-gate bipolar transistor (IGBT) module under low-pressure conditions. The estimation of electric field distribution is conducted through 3D finite element analysis (FEA) using COMSOL Multiphysics®. The procedure of PD detection and transient modeling is performed in MATLAB for two pressure levels (atmospheric and half-atmospheric). The case study is the IGBT module with a void or two voids in the proximity of triple joints. The single-void case demonstrates that at half-atmospheric pressure, the intensity of discharges per voltage cycle increases by more than 40% compared to atmospheric pressure. The double-void case further shows that a void that is harmless at sea level can turn into an additional source of aging and couple with the other voids to escalate PD intensity by a factor of two or more.

Performances of Al-xLi alloy anodes for Al-air batteries in alkaline electrolyte

The electrochemical behavior and discharge performance of as-cast Al-xLi (x = 0, 0.1, 0.3 and 0.5 wt%) alloy anodes were evaluated in this work. The results obtained by OM (optical microscope) and XRD (X-ray diffraction meter) show that the trace Li element cannot cause a grain refinement effect but change the grain orientation of Al-xLi alloys. The high-resolution TEM (transmission electron microscope) image reveals spherical morphology and coherent characteristics of Al3Li phase. The electrochemical tests indicate that Al-0.1Li alloy exhibits higher discharge activity and more appropriate self-corrosion rate than the other ones. The discharge test shows that the Al-air cell with Al-0.1Li anode provides higher average voltage, higher anodic efficiencies and higher energy density at different current densities. Furthermore, the dissolution mechanism of Al-xLi anodes based on microstructure, electrochemical response and corrosion characterization is systematically described and discussed. This work is conducive to improving the performance of Al anodes and also makes a contribution to optimizing Al anode composition.

Painful diabetic neuropathy leads to functional CaV3.2 expression and spontaneous activity in skin nociceptors of mice

Painful diabetic neuropathy occurs in approximately 20% of diabetic patients with underlying pathomechanisms not fully understood. We evaluated the contribution of the CaV3.2 isoform of T-type calcium channel to hyperglycemia-induced changes in cutaneous sensory C-fiber functions and neuropeptide release employing the streptozotocin (STZ) diabetes model in congenic mouse strains including global knockouts (KOs). Hyperglycemia established for 3–5 weeks in male C57BL/6J mice led to major reorganizations in peripheral C-fiber functions. Unbiased electrophysiological screening of mechanosensitive single-fibers in isolated hairy hindpaw skin revealed a relative loss of (polymodal) heat sensing in favor of cold sensing. In healthy CaV3.2 KO mice both heat and cold sensitivity among the C-fibers seemed underrepresented in favor of exclusive mechanosensitivity, low-threshold in particular, which deficit became significant in the diabetic KOs. Diabetes also led to a marked increase in the incidence of spontaneous discharge activity among the C-fibers of wildtype mice, which was reduced by the specific CaV3.2 blocker TTA-P2 and largely absent in the KOs. Evaluation restricted to the peptidergic class of nerve fibers - measuring KCl-stimulated CGRP release - revealed a marked reduction in the sciatic nerve by TTA-P2 in healthy but not diabetic wildtypes, the latter showing CGRP release that was as much reduced as in healthy and, to the same extent, in diabetic CaV3.2 KOs. These data suggest that diabetes abrogates all CaV3.2 functionality in the peripheral nerve axons. In striking contrast, diabetes markedly increased the KCl-stimulated CGRP release from isolated hairy skin of wildtypes but not KO mice, and TTA-P2 reversed this increase, strongly suggesting a de novo expression of CaV3.2 in peptidergic cutaneous nerve endings which may contribute to the enhanced spontaneous activity. De-glycosylation by neuraminidase showed clear desensitizing effects, both in regard to spontaneous activity and stimulated CGRP release, but included actions independent of CaV3.2. However, as diabetes-enhanced glycosylation is decisive for intra-axonal trafficking, it may account for the substantial reorganizations of the CaV3.2 distribution. The results may strengthen the validation of CaV3.2 channel as a therapeutic target of treating painful diabetic neuropathy.

The “hard, relentless, never-ending” work of focusing on discharge: a qualitative study of managers' perspectives

PurposeInterventions to hasten patient discharge continue to proliferate despite evidence that they may be achieving diminishing returns. To better understand what such interventions can be expected to accomplish, the authors aim to critically examine their underlying program theory.Design/methodology/approachWithin a broader study on patient flow, spanning 10 jurisdictions across Western Canada, the authors conducted in-depth interviews with 300 senior, middle and frontline managers; 174 discussed discharge initiatives. Using thematic analysis informed by a Realistic Evaluation lens, the authors identified the mechanisms by which discharge activities were believed to produce their impacts and the strategies and context factors necessary to trigger the intended mechanisms.FindingsManagers' accounts suggested a common program theory that applied to a wide variety of discharge initiatives. The chief mechanism was inculcation of a sharp focus on discharge; reinforcing mechanisms included development of shared understanding and a sense of accountability. Participants reported that these mechanisms were difficult to produce and sustain, requiring continual active management and repeated (re)introduction of interventions. This reflected a context in which providers, already overwhelmed with competing demands, were unlikely to be able (or perhaps even willing) to sustain a focus on this particular aspect of care.Originality/valueThe finding that “discharge focus” emerged as the core mechanism of discharge interventions helps to explain why such initiatives may be achieving limited benefit. There is a need for interventions that promote timely discharge without relying on this highly problematic mechanism.

HMGB1-RAGE Pathway Contributes to the Abnormal Migration of Endogenous Subventricular Zone Neural Progenitors in an Experimental Model of Focal Microgyria.

Abnormal migration of subventricular zone (SVZ)-derived neural progenitor cells (SDNPs) is involved in the pathological and epileptic processes of focal cortical dysplasias (FCDs), but the underlying mechanisms are not clear. Recent studies indicated that high mobility group box 1 (HMGB1)/receptor for advanced glycation end products (RAGE) are widely expressed in epileptic specimens of FCDs, which suggests that the HMGB1-RAGE pathway is involved in the pathological and/or epileptic processes of FCDs. The present study used Nestin-GFPtg/+ transgenic mice, and we established a model of freezing lesion (FL), as described in our previous report. A "migrating stream" composed of GFP-Nestin+ SDNPs was derived from the SVZ region and migrated to the cortical FL area. We found that translocated HMGB1 and RAGE were expressed in cortical lesion in a clustered distribution pattern, which was especially obvious in the early stage of FL compared to the sham group. Notably, the number of GFP-Nestin+ SDNPs within the "migrating stream" was significantly decreased when the HMGB1-RAGE pathway was blocked by a RAGE antagonist or deletion of the RAGE gene. The absence of RAGE also decreased the activity of pentylenetetrazol-induced cortical epileptiform discharge. In summary, this study provided experimental evidence that the levels of extranuclear HMGB1 and its receptor RAGE were increased in cortical lesion in the early stage of the FL model. Activation of the HMGB1-RAGE pathway may contribute to the abnormal migration of SDNPs and the hyperexcitability of cortical lesion in the FL model.

Investigation of supraharmonics' influence on partial discharge activity using an internal cavity sample

This research paper investigated the influence of lower-order supraharmonics on partial discharge activity in an insulation system sample with a predefined spherical cavity defect. The supraharmonics were represented by repetitive sinusoidal oscillations, whose shape, amplitude, and natural frequency were based on typical trends measured or modeled in medium- to high-voltage electric subgrids containing power converters. The combination of a fundamental 50-Hz waveform and a one-per-period oscillation was applied to the test sample, and the occurring partial discharge activity was measured. Throughout the experiment, the oscillation's position and natural frequency were gradually changed. Afterward, partial discharge activity under identical conditions was simulated using an analytical model, and the phenomena observed during the experiment were explained by it. Changes accounting for the presence of supraharmonic oscillations were introduced to the model. Ultimately, conclusions about the significance of the changes in the partial discharge activity were drawn. Among those were predictions of increased aging rate, earlier inception of partial discharge activity, and suggestions for future works.

Advancements in heavy metals removal from effluents employing nano-adsorbents: Way towards cleaner production

Due to the development in science field which gives not only benefit but also introducesundesirable pollution to the environment. This pollution is due to poor discharge activities of industrial effluents into the soil and water bodies, surface run off from fields of agricultural lands, dumping of untreated wastes by municipalities, and mining activites, which deteriorates the cardinal virtue of our environment and causes menace to human health and life. Heavy metal(s), a natural constituent on earth's crust and economic important mineral, due to its recalcitrant effects creates heavy metal pollution which affects food chain and also reduces the quality of water. For this, many researchers have performed studies to find efficient methods for wastewater remediation. One of the most promising methods from economic point of view is adsorption, which is simple in design, but leads to use of a wide range of adsorbents and ease of operations. Due to advances in nanotechnology, many nanomaterials were used as adsorbents for wastewater remediation, because of their efficiency. Many researchers have reported that nanoadsorbents are unmitigatedly a fruitful solution to address this world's problem. This review presents a potent view on various classes of nanoadsorbents and their application to wastewater treatment. It provides a bird's eye view of the suitability of different types of nanomaterials for remediation of wastewater and Backspace gives up-to-date information about polymer based and silica-based nanoadsorbents.