Direct Currents Research Articles

Cooperation between Z.-T. Gramme and P.N. Yablochkov in the Field of Creating AC Generators (On the 175th Anniversary Since the Birth of P.N. Yablochkov)

The great invention of Pavel Nikolaevich Yablochkov and his vigorous activity turned mountains. Within a short period of time, electrical engineering has become a powerful driving force of world progress. The deeper we dive into the study of the Russian inventor’s history, the more of new facts and amazing aspects of his genius are revealed to us. Yablochkov’s candle operated on alternating current. The alternators that existed at that time became obsolete. New electrical machines were urgently needed. In the late 1870s, direct currents were mainly used in electrical engineering. P.N. Yablochkov had to make serious efforts to solve the problem of providing efficient power supply for his lamps. Cooperation of two great electrical engineers P.N. Yablochkov and Z.-T. Gramme led to the development of alternating current technologies and the development of the first two-phase generators, which formed the basis for the development of multiphase electric currents, an entire field in electrical engineering.

Electric Fields Induced in the Brain by Transcranial Electric Stimulation: A Review of In Vivo Recordings.

Transcranial electrical stimulation (tES) techniques, such as direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), cause neurophysiological and behavioral modifications as responses to the electric field are induced in the brain. Estimations of such electric fields are based mainly on computational studies, and in vivo measurements have been used to expand the current knowledge. Here, we review the current tDCS- and tACS-induced electric fields estimations as they are recorded in humans and non-human primates using intracerebral electrodes. Direct currents and alternating currents were applied with heterogeneous protocols, and the recording procedures were characterized by a tentative methodology. However, for the clinical stimulation protocols, an injected current seems to reach the brain, even at deep structures. The stimulation parameters (e.g., intensity, frequency and phase), the electrodes’ positions and personal anatomy determine whether the intensities might be high enough to affect both neuronal and non-neuronal cell activity, also deep brain structures.

Neuromodulation in drug-resistant epilepsy: A review of current knowledge.

Nearly 1% of the global population suffers from epilepsy. Drug-resistant epilepsy (DRE) affects one-third of epileptic patients who are unable to treat their condition with existing drugs. For the treatment of DRE, neuromodulation offers a lot of potential. The background, mechanism, indication, application, efficacy, and safety of each technique are briefly described in this narrative review, with an emphasis on three approved neuromodulation therapies: vagus nerve stimulation (VNS), deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS), and closed-loop responsive neurostimulation (RNS). Neuromodulatory approaches involving direct or induced electrical currents have been developed to lessen seizure frequency and duration in patients with DRE since the notion of electrical stimulation as a therapy for neurologic diseases originated in the early nineteenth century. Although few people have attained total seizure independence for more than 12 months using these treatments, more than half have benefitted from a 50% drop in seizure frequency over time. Although promising outcomes in adults and children with DRE have been achieved, challenges such as heterogeneity among epilepsy types and etiologies, optimization of stimulation parameters, a lack of biomarkers to predict response to neuromodulation therapies, high-level evidence to aid decision-making, and direct comparisons between neuromodulatory approaches remain. To solve these existing gaps, authorize new kinds of neuromodulation, and develop personalized closed-loop treatments, further research is needed. Finally, both invasive and non-invasive neuromodulation seems to be safe. Implantation-related adverse events for invasive stimulation primarily include infection and pain at the implant site. Intracranial hemorrhage is a frequent adverse event for DBS and RNS. Other stimulation-specific side-effects are mild with non-invasive stimulation.

The Effect of Ion Exchange Poisoning on the Ion Transport and Conduction in Polymer Electrolyte Membranes (PEMs) for Water Electrolysis

In water electrolyzers, polymer electrolyte membranes (PEMs) such as Nafion can accumulate cations stemming from salt impurities in the water supply, which leads to severe cell voltage increases. This combined experimental and computational study discusses the influence of sodium ion poisoning on the ionic conductivity of Nafion membranes and the ion transport in a thereon based water electrolysis cell. Conductivities of Nafion and aqueous solutions with the same amount of dissolved cations are measured with impedance spectroscopy and compared with respect to Nafion’s microstructure. The dynamic behavior of the voltage of a water electrolysis cell is characterized as a function of the sodium ion content and current density, showing the differences of the ion transport at alternating and direct currents. These experimental results are elucidated with a physical ion transport model for sodium ion poisoned Nafion membranes, which describes a proton depletion and sodium ion accumulation at the cathode. During proton depletion, the cathodic hydrogen evolution is maintained by the water reduction that forms hydroxide ions. Together with sodium ions from the membrane, the formed hydroxide ions can diffuse pairwise into the water supply, so that the membrane’s sodium ions can be at least partly be replaced with anodically formed protons.

Ultra-low noise current meter for measuring quickly changing currents from attoampere to nanoampere

Abstract Low-noise current meters are usually designed using high value feedback resistors. However, a high resistance reduces the maximum measurable current at a given output voltage and the maximum bandwidth at a given parasitic capacitance. Capacitive transimpedance amplifiers integrating the current to be measured correspond to a nearly infinite resistance. Here, we present a novel active reset architecture for discharging the integration capacitor that eliminates the leakage currents and charge injection of the necessary switches. This enables a capacitive current meter achieving the noise current of an ideal resistive transimpedance amplifier with an ideal resistance of 650 GΩ, while the dynamic range, bandwidth and zero-point stability are orders of magnitude greater due to the capacitive operating principle. At a 3-dB bandwidth of 50 Hz, the noise current standard deviation is σ i = 2.6 fA {\sigma _{i}}=2.6\hspace{0.1667em}\text{fA} with a dynamic range of six orders of magnitude from femto- to nanoamperes. Digitally adjusting the 3-dB bandwidth to 0.45 mHz for measuring direct currents reduces the noise by three orders of magnitude down to σ i = 8.7 aA {\sigma _{i}}=8.7\hspace{0.1667em}\text{aA} , resulting in a dynamic range of nine orders of magnitude. This is possible due to an excellent zero-point stability within ± 25 aA without temperature or humidity compensation.

Plastic injection molding dies using hybrid additively manufactured 420/CX stainless steels: electrochemical considerations

This research focused on the corrosion resistance and microstructure of hybrid additively manufactured (HAM) samples of AISI 420/CX (420/CX SS) stainless steels. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses as well as the electrochemical noise (EN) technique were used to evaluate the electrochemical behavior of the as-built and heat-treated HAM parts in NaCl solution. The results showed a more protective passive layer formed on the CX SS side. The distribution of Cr-rich M23C6 carbides in matrix of 420 SS side resulted in a lower corrosion resistance compared to the CX SS side. The noise data analysis confirmed an increase in the galvanic currents of the HAM parts after heat treatment. The stochastic analysis revealed the interface in the heat-treated condition increases pit growth more than the as-built one due to the evolution of nano-sized intermetallic compounds of Al-N/ (Cr, Nb) (N, C) at the heat-treated interface area.

Self-oscillating pump in a topological dissipative atom–cavity system

Pumps are transport mechanisms in which direct currents result from a cyclic evolution of the potential1,2. As Thouless showed, the pumping process can have topological origins, when considering the motion of quantum particles in spatially and temporally periodic potentials3. However, the periodic evolution that drives these pumps has always been assumed to be imparted from outside, as has been the case in the experimental systems studied so far4-12. Here we report on an emergent mechanism for pumping in a quantum gas coupled to an optical resonator, where we observe a particle current without applying a periodic drive. The pumping potential experienced by the atoms is formed by the self-consistent cavity field interfering with the static laser field driving the atoms. Owing to dissipation, the cavity field evolves between its two quadratures13, each corresponding to a different centrosymmetric crystal configuration14. This self-oscillation results in a time-periodic potential analogous to that describing the transport of electrons in topological tight-binding models, such as the paradigmatic Rice-Mele pump15. In the experiment, we directly follow the evolution by measuring the phase winding of the cavity field with respect to the driving field and observing the atomic motion in situ. The observed mechanism combines the dynamics of topological and open systems, and features characteristics of continuous dissipative time crystals.

Galvanic Corrosion and Fatigue Behavior of a SM480C Welded Joint Steel in a Sea-Crossing Suspension Bridge

The corrosion tendency and fatigue behavior of a SM480C welded joint in a sea-crossing suspension bridge after twenty-year exposure to a marine environment was investigated in this work. It was found that the corrosion product on the whole surface of the welded joint is loose, with many holes and cracks, which allowing corrosive media enter and reach the surface of the substrate. Localized corrosion occurred in the weld zone (WZ) and the heat-affected zone (HAZ), the maximum depth of localized corrosion in the HAZ reached 1.8 mm, and the maximum local corrosion rate is 0.082 mm/y. By using Bimetallic Conjugation Theory calculations, the galvanic effect of the welded joint was qualified, indicates that HAZ was the most corrosion susceptible area in the welded joint. The galvanic corrosion current on HAZ reached approximately 2 μA, which is much higher than the corrosion of isolated HAZ by about 6.5 times. The corrosion has an obvious influence on the fatigue performance, the elongation of the bridge deck decreases by 40%~70%, and the tensile strength decreases by 4.5%~31.33%. In order to ensure the service safety and avoid premature failure, the average thickness of the corroded bridge deck should not be less than 10 mm under the stress amplitude of 115 MPa.

Electrical Potentiometry with Intraoral Applications.

Dental implants currently in use are mainly made of titanium or titanium alloys. As these metallic elements are immersed in an electrolytic medium, galvanic currents are produced between them or with other metals present in the mouth. These bimetallic currents have three potentially harmful effects on the patient: micro-discharges, corrosion, and finally, the dispersion of metal ions or their oxides, all of which have been extensively demonstrated in vitro. In this original work, a system for measuring the potentials generated in vivo is developed. Specifically, it is an electrogalvanic measurements system coupled with a periodontal probe that allows measurement of the potentials in the peri-implant sulcus. This device was tested and verified in vitro to guarantee its applicability in vivo. As a conclusion, this system is able to detect galvanic currents in vitro and it can be considered capable of being employed in vivo, so to assess the effects they may cause on dental implants.

THE HUMAN HAIR FOLLICLE AS BATTERY WITH SHAFT AS BIPOLAR EXTENSION INTRODUCING IN VITRO EXPERIMENTS DEMONSTRATING PRESENCE OF BIPOLAR ELECTRICAL CHARGES INHERENT IN THE HUMAN HAIR SHAFT INDUCED BY THE FOLLICLE’S DC CURRENTS

The main purpose of this manuscript is to enumerate prior published in vitro individual findings by this author and others with the ultimate goal to demonstrate the human hair similarity with a DC battery. This by the hair root as the energy source and the hair shaft as a bipolar (+−) extension of the follicle’s DC currents. The human hair consists of a follicle anchored in the skin and a protruding shaft, it has also been described as a miniorgan, having its own cells division, metabolism and known to undergo aging stages; eventually reaching a point where the old hair sheds and a new hair growing cycle begins from the same follicular tissue. Using sophisticated magnetometers, magnetic fields emitted by direct currents (DC) in human hair follicle was detected and introduced in 1980. Most recently in 2015, a tabletop optical microscopy method was developed and published in 2016, thus allowing for the detection of hair follicles and shafts magnetic fields. Utilizing this novel microscopy technique, this author and others were able to again identify the follicle and shaft magnetic fields by interacting with cyano-compounds powder in solution. Qualitative images are presented where the bipolar property of the shaft is inferred by using fresh blood on a glass slide. This inference was rationalized since blood tissue material is known to express negative charges, thus repelled by an equal charge. The shaft is repeatedly shown in experiments to express a contralateral positive side. The positive side triggering fibrin formation documented by images showing intricate networks indicative of undergoing blood coagulation. Conversely, the contralateral negative side is shown as repelling blood tissue, thus inhibiting coagulation. Additionally, other experiments elucidate the follicle as a DC energy source; and the hair shaft as its bipolar extension.

Investigation of the Corrosion Mechanism for Sulfate Reducing Bacteria (SRB) Using a Split-Chamber Zero Resistance Ammetry Technique

Microbiologically influenced corrosion (MIC) is one of the most aggressive forms of corrosion leasing to infrastructure and equipment damage in various industries, including oil and gas, water systems, medical devices, marine environments, nuclear waste storage facilities, and aviation fuel systems and storage. During the last 10 year, PHMSA estimates that MIC has caused 503 internal corrosion incidents at a reported property damage of $188 million and a loss of 53,000 barrels of oil. Some common bacteria associated with MIC are sulfate-reducing bacteria (SRB), iron and CO2 reducing bacteria and iron and manganese oxidizing bacteria. SRB are generally considered the most aggressive group of bacteria in pipeline systems that causes MIC and pitting, especially of carbon steel in the oil and gas industry. SRB are facultative anaerobes and thrive in anoxic environments, using sulfate as a terminal electron acceptor and producing hydrogen sulfide (H2S) as a metabolic byproduct. Furthermore, SRBs also can reduce both nitrate and thiosulfate and obtain their energy from organic nutrients, such as lactate.Electrochemical techniques to monitor for MIC focus on studying the electrochemical characteristics of the interface or mass transport properties of a system that are modified by the microbiological activities. Polarization sensors, such as the BIOX system or BioGeorge, use polarization based on a galvanic couple between a stainless steel electrode and a sacrificial anode. The measured galvanic current is proportional to biofilm that has grown on the electrode surface. Other electrochemical sensors use electrochemical impedance spectroscopy (EIS) or amperometry to measure biofilm thickness by comparing the electrochemical signatures of a reference channel (without bacteria) to a measurement channel (exposed to bacteria); while sensors based on electrochemical resistance use linear polarization measurements to determine the amount of biofilm on an electrode surface. Electro hydrodynamical impedance has also been used to measure the diffusion coefficient in a biofilm and correlate to biofilm growth and thickness. While these approaches can accurately predict the presence and/or thickness of a biofilm on a metal surface, they cannot determine the risk of MIC associated with biofilm formation, as the presence of a biofilm does not necessarily mean that a surface experiences MIC. Additionally, many of the techniques are destructive or require visual examination of the surface after analysis.This work presents a split-chamber zero resistance ammetry (SC-ZRA)-based approach to overcome the limitations to MIC monitoring described above and serve as a screening system to determine the risk of MIC associated with certain microorganisms or groups of microorganisms. Previous work using a split-chamber approach to assess MIC was used by Daumus for the study of stainless steel corrosion in the presence of sulfate reducing bacteria, and subsequently used by Miller et al to evaluate MIC under aerobic, Fe (III)- and nitrate-reducing conditions. In this approach, two identical electrochemical cells (chambers) are separated by an ion-transport membrane. Each chamber contains an identical electrode of the same material which are electrically connected through a zero-resistance ammeter. When one of the chambers is inoculated with microorganisms, the galvanic current between the two electrodes is measured through the zero ammeter. This configuration mimics the microbiologically induced development of localized anodic and cathodic patches on a metal surface that leads to corrosion. The flow of electrons (difference in corrosion current between the two chambers) depends solely on the microbiological activities of bacteria in one of the two chambers, so the influence of the microorganisms on MIC, as well as the extent of corrosion, can be quantified.Using the SC-ZRA technique we were able to characterize the mechanism and electrochemical signatures of SRB corrosion. Specifically, we found that in split-chamber incubations containing an electron donor, electrons flow from the inoculated to the uninoculated chambers. While the current direction could be interpreted as electron transfer such as in a microbial fuel cell, these systems deploy inert graphite electrodes. When used for MIC characterization, the SC-ZRA uses reactive carbon steel electrodes. Indeed, when positive current was detected, greater corrosion was detected on WE1, which is consistent with redox couples, as well as previous work to characterize MIC using SC-ZRA measurements. After depletion of an electron donor, SRB uses electrons from the metals surface as an electron donor reversing the flow of electrons from the uninoculated to the inoculated chamber. In future work, this technique can be used to provide a mechanistic understanding and a monitoring tool for corrosion of metals that are exposed to SRB under a variety of redox regimes.

Direct current compensation – field experience under service conditions

Modern grain oriented core steel used in power transformers has a very high magnetic conductivity. This advanced material makes the transformer susceptible even for small direct current (DC) in the power grid. Already minor DC increases the no-load noise and no-load losses of the transformer considerably. This effect is known as half-cycle saturation. In order to overcome these parasitic DC an active compensation method called “DC compensation” (DCC) was recently developed by Siemens [1]. The question about the origin of the DC is not fully answered yet. However the following sources have been already identified: power electronics, renewable power generation (wind, solar), HVDC transmission lines and DC operated railroad or subway systems. The parasitic direct currents can flow over the power lines to ground or asymmetrically in the power line phases only. In this paper field data, a four-month DC load profile, of single-phase core type transformers, equipped with active DC compensation, are shown. The discussed unit, a bank of three single-phase autotransformers, is in service mainly exposed to DC flowing from the overhead lines through the windings to the common neutral. DC magnitude varies from 0.05 A to about 0.2 A DC per phase throughout the day. From factory tests we know that only 0.2 A DC causes a noise increase of 5.6 dB(A) compared to the noise level without any DC compensation. This might cause troubles at the substation when noise has to be below a guaranteed level. Data analysis of the field data shows that the DC throughout the day follows a clear profile with its highest level during midnight and lunch time. This might indicate a correlation to the load and / or switching operations in the grid to adjust to the actual needed load. However, the DC compensation equipment fully eliminates the direct flux in the core and thus the DC caused increase in noise.

Results of Mathematical Simulation of Transient Processes for the Sea Shelf Conditions

Abstract —Electrical exploration measurements in water areas and on land are carried out to study the electromagnetic (EM) properties of geological formations. A distinctive feature of aquatic electrical exploration is associated with the specific influence of a water column. Numerical calculations of the EM signal of the transient process for electrical lines in the axial region of the source under the conditions of marine waters with a depth of 50 to 250 m are presented in order to demonstrate how an induced polarization (IP) signal manifests itself in a transient process signal on different setups, to identify differences in the manifestation of galvanic induced polarization (GIP) and induction-induced polarization (IIP) in a transient process signal, and to substantiate these differences. The influence of the setup dimensions on the manifestation of IP during a transient process is studied by analyzing a change in the transient signal (ΔU(t)), the final difference of the transient process signal (Δ2U(t)) and transform P1(t) (ratio of these values) for a horizontal electrical setup with a source (AB) 50 to 2000 m in length, a three-electrode measuring line (M1M2M3) 50 to 2000 m in length, a distance between the source centers and the measuring line M1M3 (spacing, r) from 100 to 4000 m. Some of these parameters are used in differential-normalized electrical prospecting (DNME). The comparison of ΔU(t) and Δ2U(t) and their transforms in conducting and conducting-polarizable models under the same conditions is performed. The setup is placed on the surface and inside a conducting medium (a sea shelf water column) with a conducting polarizable base (geologic medium (ground) covered with a water layer). The polarizability of the base is taken into account by introducing a frequency-dependent resistivity using the Cole—Cole equation. It is shown by the calculations performed that the transient process components associated with the formation of an EM field and with GIP and IIP manifest themselves in dissimilar ways on differently sized setups at various depths. In a water area, IP manifests itself in two ways, being associated with both galvanic and eddy currents. In previous practical measurements, IIP was considered to be associated with interference, but this signal is simulated and can be regarded as information about IP. The factor influencing the IP manifestation in a transient process signal is a reduced setup height (hΔ), i.e., a distance between a setup and a sea bottom (polarizable base of the model) attributed to the AB line. Depending on the reduced setup height, the IP signal in transform P1(t) can manifest itself as an ascending branch at later times or appear as a descending branch passing into the negative values of P1. The pulse impact duration and the transient process measurements affect the contrasting manifestation of the polarizable base in the signal, but the measurements performed when the setup is being towed impose certain restrictions. The optimal parameters of the EM survey for IP studies should ensure a sufficient polarization range and the proper quality of measurements. The software used in the calculations was developed by OOO Sibirskaya Geofizicheskaya Nauchno-Proizvodstvennaya Kompaniya.

Scanning gradiometry with a single spin quantum magnetometer

Quantum sensors based on spin defects in diamond have recently enabled detailed imaging of nanoscale magnetic patterns, such as chiral spin textures, two-dimensional ferromagnets, or superconducting vortices, based on a measurement of the static magnetic stray field. Here, we demonstrate a gradiometry technique that significantly enhances the measurement sensitivity of such static fields, leading to new opportunities in the imaging of weakly magnetic systems. Our method relies on the mechanical oscillation of a single nitrogen-vacancy center at the tip of a scanning diamond probe, which up-converts the local spatial gradients into ac magnetic fields enabling the use of sensitive ac quantum protocols. We show that gradiometry provides important advantages over static field imaging: (i) an order-of-magnitude better sensitivity, (ii) a more localized and sharper image, and (iii) a strong suppression of field drifts. We demonstrate the capabilities of gradiometry by imaging the nanotesla fields appearing above topographic defects and atomic steps in an antiferromagnet, direct currents in a graphene device, and para- and diamagnetic metals.

Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex for Treatment of Neuropsychiatric Disorders.

BackgroundThe dorsolateral prefrontal cortex (DLPFC) is a key node of the frontal cognitive circuit. It is involved in executive control and many cognitive processes. Abnormal activities of DLPFC are likely associated with many psychiatric diseases. Modulation of DLPFC may have potential beneficial effects in many neural and psychiatric diseases. One of the widely used non-invasive neuromodulation technique is called transcranial direct current stimulation (or tDCS), which is a portable and affordable brain stimulation approach that uses direct electrical currents to modulate brain functions.ObjectiveThis review aims to discuss the results from the past two decades which have shown that tDCS can relieve clinical symptoms in various neurological and psychiatric diseases.MethodsHere, we performed searches on PubMed to collect clinical and preclinical studies that using tDCS as neuromodulation technique, DLPFC as the stimulation target in treating neuropsychiatric disorders. We summarized the stimulation sites, stimulation parameters, and the overall effects in these studies.ResultsOverall, tDCS stimulation of DLPFC could alleviate the clinical symptoms of schizophrenia, depression, drug addiction, attention deficit hyperactivity disorder and other mental disorders.ConclusionThe stimulation parameters used in these studies were different from each other. The lasting effect of stimulation was also not consistent. Nevertheless, DLPFC is a promising target for non-invasive stimulation in many psychiatric disorders. TDCS is a safe and affordable neuromodulation approach that has potential clinical uses. Larger clinical studies will be needed to determine the optimal stimulation parameters in each condition.

Endogenous Pain Modulation in Response to a Single Session of Percutaneous Electrolysis in Healthy Population: A Double-Blinded Randomized Clinical Trial.

The purpose of this double-blinded randomized controlled trial was to investigate whether percutaneous electrolysis (PE) is able to activate endogenous pain modulation and whether its effects are dependent on the dosage of the galvanic current. A total of 54 asymptomatic subjects aged 18–40 years were randomized into three groups, receiving a single ultrasound-guided PE intervention that consisted of a needle insertion on the lateral epicondyle tendon: sham (without electrical current), low-intensity (0.3 mA, 90 s), and high-intensity (three pulses of 3 mA, 3 s). Widespread pressure pain thresholds (PPT), conditioned pain modulation (CPM), and temporal summation (TS) were assessed in the elbow, shoulder, and leg before and immediately after the intervention. Both high and low intensity PE protocols produced an increase in PPT in the shoulder compared to sham (p = 0.031 and p = 0.027). The sham group presented a significant decrease in the CPM (p = 0.006), and this finding was prevented in PE groups (p = 0.043 and p = 0.025). In addition, high-intensity PE decreased TS respect to sham in the elbow (p = 0.047) and both PE groups reduced TS in the leg (p = 0.036 and p = 0.020) without significant differences compared to sham (p = 0.512). Consequently, a single PE intervention modulated pain processing in local and widespread areas, implying an endogenous pain modulation. The pain processing effect was independent of the dosage administrated.

Giant magnetochiral anisotropy from quantum-confined surface states of topological insulator nanowires

Wireless technology relies on the conversion of alternating electromagnetic fields into direct currents, a process known as rectification. Although rectifiers are normally based on semiconductor diodes, quantum mechanical non-reciprocal transport effects that enable a highly controllable rectification were recently discovered1–9. One such effect is magnetochiral anisotropy (MCA)6–9, in which the resistance of a material or a device depends on both the direction of the current flow and an applied magnetic field. However, the size of rectification possible due to MCA is usually extremely small because MCA relies on inversion symmetry breaking that leads to the manifestation of spin–orbit coupling, which is a relativistic effect6–8. In typical materials, the rectification coefficient γ due to MCA is usually ∣γ∣ ≲ 1 A−1 T−1 (refs. 8–12) and the maximum values reported so far are ∣γ∣ ≈ 100 A−1 T−1 in carbon nanotubes13 and ZrTe5 (ref. 14). Here, to overcome this limitation, we artificially break the inversion symmetry via an applied gate voltage in thin topological insulator (TI) nanowire heterostructures and theoretically predict that such a symmetry breaking can lead to a giant MCA effect. Our prediction is confirmed via experiments on thin bulk-insulating (Bi1−xSbx)2Te3 (BST) TI nanowires, in which we observe an MCA consistent with theory and ∣γ∣ ≈ 100,000 A−1 T−1, a very large MCA rectification coefficient in a normal conductor.

Galvanic Coupling of Copper and Carbon Steel in the Presence of Bentonite Clay and Chloride

The long-term containment plan for Canada’s used nuclear fuel employs copper-coated carbon steel (CS) containers encased in compacted bentonite clay buffer boxes. In the hypothetical case of a through-coating defect, galvanic interactions between the Cu coating and the CS vessel are dependent on the conditions at the container surface. A zero-resistance ammeter was used to measure the galvanic current between Cu and CS electrodes at various area ratios in the presence of aerated 1 M NaCl and obstructive layers of bentonite slurry. The presence of bentonite resulted in an order of magnitude decrease in the corrosion rate of the steel. As shown by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and Raman spectroscopy, the extent of steel corrosion decreased significantly in the presence of bentonite slurry, favouring mild surface etching over oxide growth. Electrochemical impedance spectroscopy (EIS) measurements showed that the total impedance on carbon steel generally increased with bentonite layer thickness, but the total impedance on Cu plateaued when the layer exceeded 6 mm, consistent with trends in galvanic current density on carbon steel. The benign conditions produced by the bentonite slurry are attributed to the slightly alkaline pH and the hindrance of O2 diffusion.

Study of the Operating State of a Synchronous Motor Electric Drive by Means of Changes Estimation of the Stator Current Behavior

The article proposes a model for the research of the changes in the operating state of a three-phase synchronous motor used in an electric drive of the technological mechanisms. The model has been implemented in the MATLAB software environment based on the Park-Gorev equations, which has found wide application in Electromechanics. It has become possible to estimate during transient changes in the electromagnetic torque of the electric motor along the axes d and q, and stator currents in phases a, b, c, as well as the changes in the ratios of the currents of the reverse and direct sequence. It is confirmed that when the supply voltage of the network and the load torque of the technological mechanism change, in the stator phase windings, currents of the reverse sequence appear. For the considered electric drive motor, the reverse sequence current does not exceed 1.5% of the direct sequence currents, meanwhile the permissible limit according to the standard is 8%. The research model of the operating state of the synchronous motor can be successfully used to identify the pre-emergency state of the operated electric drive systems, assess the causes of their occurrence, and make optimal decisions. The obtained results can also be successfully used for intelligent diagnostics in order to develop automated control systems.

Visualization of Concentration Gradients and Colloidal Dynamics under Electrodiffusiophoresis.

In this work, we present an experimental study of the dynamics of charged colloids under direct currents and gradients of chemical species (electrodiffusiophoresis). In our approach, we simultaneously visualize the development of concentration polarization and the ensuing dynamics of charged colloids near electrodes. With the aid of confocal microscopy and fluorescent probes, we show that the passage of current through water confined between electrodes, separated about a hundred microns, results in significant pH gradients. Depending on the current density and initial conditions, steep pH gradients develop, thus becoming a significant factor in the behavior of charged colloids. Furthermore, we show that steep pH gradients induce the focusing of charged colloids away from both electrodes. Our results provide the experimental basis for further development of models of electrodiffusiophoresis and the design of non-equilibrium strategies for the fabrication of advanced materials.