High Frequency Alternating Current Research Articles

The Duration and Intensity of High Frequency Alternating Current Influences the Degree and Recovery of Nerve Conduction Block.

The purpose of this paper is to investigate the persistence of nerve blockade beyond the duration of applying high frequency alternating current (HFAC) to thinly myelinated and non-myelinated fibers, also termed a "carry-over effect". In this study, we used electrically-evoked compound action potentials from isolated rat vagus nerves to assess the influence of 5 kHz HFAC amplitude and duration on the degree of the carry-over effect. Current amplitudes from 1-10 mA and 5 kHz durations from 10-120 seconds were tested. By testing 20 different combinations of 5 kHz amplitude and duration, we found a significant interaction between 5 kHz amplitude and duration on influencing the carry-over effect. The degree of carry-over effect was dependent on 5 kHz amplitude, as well as duration. Utilizing the carry-over effect may be useful in designing energy efficient nerve blocking algorithms for the treatment of diseases influenced by nerve activity.

High-Frequency AC Heating Strategy of Electric Vehicle Power Battery Pack in Low-Temperature Environment.

In this paper, a heating strategy using high-frequency alternating current (AC) is proposed to internally heat lithium-ion batteries (LIB) at low temperatures. The strategy aims to strike a good balance between rapid heating of the battery at low temperatures and minimizing damage to the battery's lifespan without the need for an additional power source. The strategy presents an electrochemical-thermal coupling model to simulate and predict the temperature rise and temperature distribution of a 50 A h LiFePO4 square battery at different C-rates, the effect of high-frequency AC on battery life, and the validity of the model as verified by experiments. The experimental and simulation results show that this strategy can achieve faster heating speeds and better temperature consistency without affecting battery life. The best heating effect can be achieved at a frequency of 500 Hz (4.2C), and the temperature of the battery rises from 253.15 to 278.15 K within 365 s, for an average heating rate of 3.29 K/min. Researching low-temperature AC heating methods has important value for energy conservation because it can improve heating efficiency, expand application areas, promote technological innovation, and enhance product quality.

Effect of percutaneous electrical stimulation with high-frequency alternating currents at 30 kHz on the sensory-motor system.

Unmodulated high-frequency alternating currents (HFAC) are employed for producing peripheral nerves block. HFAC have been applied in humans with frequencies up to 20 kHz, whether transcutaneously, percutaneously, or via surgically-implanted electrodes. The aim of this study was to assess the effect of percutaneous HFAC, applied with ultrasound-guided needles at 30 kHz, on the sensory-motor nerve conduction of healthy volunteers. A parallel, double-blind, randomized clinical trial with a placebo control was conducted. Percutaneous HFAC at 30 kHz or sham stimulation was applied via ultrasound-guided needles in 48 healthy volunteers (n = 24 in each group) for 20 min. The assessed outcome variables were pressure pain threshold (PPT), mechanical detection threshold (MDT), maximal finger flexion strength (MFFS), antidromic sensory nerve action potential (SNAP), hand temperature, and subjective sensations by the participants. The measurements were recorded pre-intervention, during the stimulation (at 15 min), immediately post-intervention (at 20 min), and 15 min after the end of treatment. The PPT increased in the active group compared with sham stimulation, both during the intervention [14.7%; 95% confidence interval (CI): 4.4-25.0], immediately post-intervention (16.9%; 95% CI: -7.2-26.5), and 15 min after the end of the stimulation (14.3%; 95% CI: 4.4-24.3) (p < 0.01). The proportion of participants who reported feelings of numbness and heaviness was significantly higher in the active group (46 and 50%, respectively) than in the sham group (8 and 18%, respectively) (p < 0.05). No intergroup differences were observed in the remaining outcome variables. No unexpected adverse effects derived from the electrical stimulation were reported. Percutaneous stimulation with HFAC at 30 kHz applied to the median nerve increased the PPT and subjective perception of numbness and heaviness. Future research should evaluate its potential therapeutic effect in people with pain. https://clinicaltrials.gov/ct2/show/NCT04884932, identifier NCT04884932.

Use of an invertebrate animal model (Aplysia californica) to develop novel neural interfaces for neuromodulation.

New tools for monitoring and manipulating neural activity have been developed with steadily improving functionality, specificity, and reliability, which are critical both for mapping neural circuits and treating neurological diseases. This review focuses on the use of an invertebrate animal, the marine mollusk Aplysia californica, in the development of novel neurotechniques. We review the basic physiological properties of Aplysia neurons and discuss the specific aspects that make it advantageous for developing novel neural interfaces: First, Aplysia nerves consist only of unmyelinated axons with various diameters, providing a particularly useful model of the unmyelinated C fibers in vertebrates that are known to carry important sensory information, including those that signal pain. Second, Aplysia's neural tissues can last for a long period in an ex vivo experimental setup. This allows comprehensive tests such as the exploration of parameter space on the same nerve to avoid variability between animals and minimize animal use. Third, nerves in large Aplysia can be many centimeters in length, making it possible to easily discriminate axons with different diameters based on their conduction velocities. Aplysia nerves are a particularly good approximation of the unmyelinated C fibers, which are hard to stimulate, record, and differentiate from other nerve fibers in vertebrate animal models using epineural electrodes. Fourth, neurons in Aplysia are large, uniquely identifiable, and electrically compact. For decades, researchers have used Aplysia for the development of many novel neurotechnologies. Examples include high-frequency alternating current (HFAC), focused ultrasound (FUS), optical neural stimulation, recording, and inhibition, microelectrode arrays, diamond electrodes, carbon fiber microelectrodes, microscopic magnetic stimulation and magnetic resonance electrical impedance tomography (MREIT). We also review a specific example that illustrates the power of Aplysia for accelerating technology development: selective infrared neural inhibition of small-diameter unmyelinated axons, which may lead to a translationally useful treatment in the future. Generally, Aplysia is suitable for testing modalities whose mechanism involves basic biophysics that is likely to be similar across species. As a tractable experimental system, Aplysia californica can help the rapid development of novel neuromodulation technologies.

Use of a bio-electronic device comprising of targeted dual neuromodulation of the hepatic and celiac vagal branches demonstrated enhanced glycemic control in a type 2 diabetic rat model as well as in an Alloxan treated swine model.

There is an unmet need for new type 2 diabetes treatments providing improved efficacy, durability and customized to improve patient's compliance. Bio-electronic neuromodulation of Vagus nerve branches innervating organs that regulate plasma glucose, may be a method for treating type 2 diabetes. The pancreas has been shown to release insulin during Vagus stimulation. The hepatic vagal branch, innervating the liver, has been shown to decrease glucose release and decrease insulin resistance following ligation. However, standalone stimulation of the Vagus nerve has shown mixed results and Vagus nerve ligation has undesirable effects. Little is known; however, of the effect on plasma glucose with combined neuromodulation consisting of stimulation of the celiac branch innervating the pancreas with simultaneous high frequency alternating current (HFAC) blockade of the hepatic branch. This study tested the effects of this approach on increasing glycemic control in rat a model of type 2 diabetes and Alloxan treated swine. Zucker obese (fatty) male rats (ZDF fa/fa) were used as a model of type 2 diabetes as well as glucose intolerant Alloxan treated swine. In ZDF rat experiments glycemic control was accessed with an intravenous glucose tolerance test during HFAC-induced hepatic branch block with concurrent celiac stimulation (HFAC + stimulation). In swine experiments glycemic control was accessed by an oral glucose tolerance test during HFAC + stimulation. Insulin measurements were taken prior to and following swine experiments giving insight into beta cell exhaustion. Histopathology was conducted to determine safety of HFAC + stimulation on Vagal branches. Zucker rats demonstrated a significant improvement to an intravenous glucose tolerance test during HFAC + stimulation compared to sham. There was no significant difference from sham compared to hepatic vagotomy or celiac stimulation. In Alloxan treated swine, when subjected to HFAC + stimulation, there was a significant improvement in glycemic control as measured by an improvement on oral glucose tolerance tests and a decrease in fasting plasma glucose. Insulin responses were similar prior to and following HFAC + stimulation experiments. Histopathology demonstrated healthy swine Vagus nerves. Electrical blockade of the hepatic Vagus branch with simultaneous stimulation of the celiac Vagus branch may be a novel, adjustable and localized approach for a treatment of type 2 diabetes.

A Novel Power Processing Unit (PPU) System Architecture Based on HFAC Bus for Electric Propulsion Spacecraft

This article proposes a novel power processing unit (PPU) system architecture based on the high-frequency alternating current (HFAC) bus for electric propulsion spacecraft. The proposed PPU system architecture takes the HFAC output of the inverter network in the main load power supply as the bus while supplying power for other low-power supplies. Compared with the conventional PPU system architecture, the number of transistors is significantly reduced, and the outputs of low-power supplies are regulated with nonisolated controllers, leading to a lower cost, more compact size, and higher reliability. Moreover, the redundancy design and the fault mode analysis are introduced, which greatly improve the flexibility of the fault operation strategies. Finally, the test on the electrical characteristic of the HFAC bus in the experimental prototype proves the feasibility and stability of the proposed system architecture. The obvious performance enhancement is further demonstrated through a systematic comparison with the conventional PPU system architecture.

PO224 / #580 EFFECT OF PERCUTANEOUS HIGH-FREQUENCY ALTERNATING CURRENT STIMULATION OVER THE MEDIAN NERVE ON EVOKED PAIN WITH 30 KHZ IN HEALTHY VOLUNTEERS. A RANDOMIZED CONTROLLED CLINICAL TRIAL: E-POSTER VIEWING

In recent years, experimental animal studies have demonstrated that no modulated high frequency alternating currents (HFAC) produce a rapid and reversible peripheral nerve block without causing damage to the nerve [1]. Clinical studies to date have investigated transcutaneous stimulation protocols leading to an increase in somatosensory thresholds [2]. Pain improvements have been demonstrated in humans with 10 and 20 kHz applications with implanted electrodes [3]. The objective of this study was to determine the effect on pressure pain threshold (PPT) of percutaneous ultrasound-guided stimulation of the median nerve with alternating currents of 30 kHz.

Effect of Percutaneous Electric Stimulation with High-Frequency Alternating Currents on the Sensory-Motor System of Healthy Volunteers: A Double-Blind Randomized Controlled Study

Former studies investigated the application of high-frequency alternating currents (HFAC) in humans for blocking the peripheral nervous system. The present trial aims to assess the effect of HFAC on the motor response, somatosensory thresholds, and peripheral nerve conduction when applied percutaneously using frequencies of 10 kHz and 20 kHz in healthy volunteers. A parallel, placebo-controlled, double-blind, randomized clinical trial was conducted. Ultrasound-guided HFAC at 10 kHz and 20 kHz and sham stimulation were delivered to the median nerve of 60 healthy volunteers for 20 min. The main assessed variables were the maximum isometric flexion strength (MFFS) of the index finger, myotonometry, pressure pain threshold (PPT), mechanical detection threshold (MDT), and sensory nerve action potential (SNAP). A decrease in the MFFS is observed immediately postintervention compared to baseline, both in the 10 kHz group (−8.5%; 95% CI −14.9 to −2.1) and the 20 kHz group (−12.0%; 95% CI −18.3 to −5.6). The between-group comparison of changes in MFFS show a greater reduction of −10.8% (95% CI −19.8 to −1.8) immediately postintervention in the 20 kHz compared to the sham stimulation group. The percutaneous stimulation applying 20 kHz HFAC to the median nerve produces a reversible postintervention reduction in strength with no adverse effects.

Plasma-assisted flame stabilization by AC dielectric barrier discharge in burst mode

Compared to the continuous mode of a high-frequency alternating current (HFAC) source, the burst mode is believed to be capable of controlling flow and combustion while saving discharge energy. Thus, the effect of burst mode on plasma-assisted flame stabilization, which is driven by an HFAC source, is investigated based on a plasma manipulation diffusion flame experiment system. A specially designed injector with a coaxial dielectric barrier discharge configuration is used to generate a methane-air diffusion flame and air plasma. The influence of the actuating parameters of the burst mode on plasma flame stabilization and the discharge power consumption are studied. The results show that the plasma injector has the typical volt–ampere characteristics of dielectric barrier discharge. The discharge clearly exhibits regular unsteady operation characteristics when the source is in burst mode. Two flame stability thresholds are found with increasing discharge voltage. According to the first and second flame stability threshold values and the flame pattern, raising the control frequency and the duty cycle is favorable for flame stabilization. However, for a fixed duty cycle of 50%, because the time scale of the actuator-off duration is longer than that of combustion, when the control frequency is too low, the flame cannot be stabilized even though the applied voltage is very high. For a fixed control frequency of 100 Hz, the flame is also difficult to stabilize when the duty cycle is too small. Mainly due to the unsteady gasdynamic effects of plasma in the burst mode, this approach can achieve the same flame stabilization effect as that of the continuous mode while reducing the energy consumption. The cost-effectiveness ratios of the two optimum actuation schemes are only 6.4% and 10.1%. In addition, the burst mode is better than the continuous mode in avoiding undesirable arc discharge. To better stabilize the flame while maintaining a relatively low cost-effectiveness ratio, actuator setting schemes with high frequency and a small duty cycle should be selected.

A high frequency AC heater based on switched capacitors for lithium-ion batteries at low temperature

Lithium-ion batteries suffer from significant performance deterioration at subzero temperatures, which brings difficulty to the promotion of electric vehicles. In this paper, a high frequency alternating current (AC) heater based on switched capacitors is proposed which can heat batteries with fast speed and good uniformity without external energy supply. The optimal heating frequency is determined based on particle swarm optimization to obtain the fastest heating speed. The proposed heating topology only needs one pair of pulse width modulation signals to drive four MOSFETs to circulate an alternating current between the batteries and switched capacitors, leading to easy control with simple structure and low cost. The effectiveness of the proposed AC heater is validated under different heating frequencies at initial temperature −20°C and –25°C, respectively. Experimental results show that by circulating an alternating current with the optimal heating frequency of 10 kHz, the proposed heater can heat lithium-ion batteries from -20°C to 0°C within 2.2min, consuming only 5.4% cell energy, and can heat lithium-ion batteries from -25°C to 0°C within 9 min, consuming only 7.8% cell energy.

Upward flow boiling of HFE-7000 in high frequency AC electric fields

Abstract An experimental investigation of upward flow boiling of HFE-7000 has been conducted in a vertical tube under a high frequency alternating current (AC) electric field with the aid of high speed photography. Importantly, the test section was coated with 600 nm transparent Indium Tin Oxide (ITO) layer allowing visual access to the boiling dynamics within the tube while simultaneously functioning as an electrical heater element for the heat transfer and electrode for establishing the electric field. Experiments were performed for a constant mass flux of G=100 kg/m2s, inlet subcooling of 2K, applied heat flux ranging between 5 to 50 kW/m2, applied voltages from 0 to 10 kVp-p AC and frequencies of 100 Hz, 1000 Hz and 10,000 Hz. For the 100 Hz applied frequency, the evidence supports the hypothesis that there are strong electrophoretic forces augmenting the heat and mass transfer phenomenon, with better than two-fold enhancement in the heat transfer at low heat fluxes. This tends to diminish with applied heat flux. Interestingly, the EHD enhancement increases for all heat flux levels when the frequency is increased to 1000 Hz, with an observed change to polarization-force dominated EHD augmentation. Increasing further to 10,000 Hz results in diminished enhancement, resulting in a peak enhancement at 1000 Hz.

High-Frequency Alternating Current Block Using Macro-Sieve Electrodes: A Pilot Study.

Background and objectiveHigh-frequency alternating current (HFAC) can yield a rapid-acting and reversible nerve conduction block. The present study aimed to demonstrate the successful implementation of HFAC block delivery via regenerative macro-sieve electrodes (MSEs).MethodsDual-electrode assemblies in two configurations [dual macro-sieve electrode-1 (DMSE-I), DMSE-II] were fabricated from pairs of MSEs and implanted in the transected and subsequently repaired sciatic nerves of two male Lewis rats. After four months of postoperative nerve regeneration through the MSEs' transit zones, the efficacy of acute HFAC block was tested for both configurations. Frequencies ranging from 10 kHz to 42 kHz, and stimulus amplitudes with peak-to-peak voltages ranging from 2 V to 20 V were tested. Evoked muscle force measurement was used to quantify the nerve conduction block.ResultsHFAC stimulation delivered via DMSE assemblies obtained a complete block at frequencies of 14 to 26 kHz and stimulus amplitudes of 12 to 20 V p-p. The threshold voltage for the complete block showed an approximately linear dependence on frequency. The threshold voltage for the partial conduction block was also approximately linear. For those frequencies that displayed both partial and complete block, the partial block thresholds were consistently lower.ConclusionThis study provides a proof of concept that regenerative MSEs can achieve complete and reversible conduction block via HFAC stimulation of regenerated nerve tissue. A chronically interfaced DMSE assembly may thereby facilitate the inactivation of targeted nerves in cases wherein pathologic neuronal hyperactivity is involved.

An HFAC block-capable and module-extendable 4-channel stimulator for acute neurophysiology

Objective. This paper describes the design, testing and use of a novel multichannel block-capable stimulator for acute neurophysiology experiments to study highly selective neural interfacing techniques. This paper demonstrates the stimulator’s ability to excite and inhibit nerve activity in the rat sciatic nerve model concurrently using monophasic and biphasic nerve stimulation as well as high-frequency alternating current (HFAC). Approach. The proposed stimulator uses a Howland Current Pump circuit as the main analogue stimulator element. 4 current output channels with a common return path were implemented on printed circuit board using Commercial Off-The-Shelf components. Programmable operation is carried out by an ARM Cortex-M4 Microcontroller on the Freescale freedom development platform (K64F). Main results. This stimulator design achieves ± 10 mA of output current with ± 15 V of compliance and less than 6 µA of resolution using a quad-channel 12-bit external DAC, for four independently driven channels. This allows the stimulator to carry out both excitatory and inhibitory (HFAC block) stimulation. DC Output impedance is above 1 M Ω. Overall cost for materials i.e. PCB boards and electronic components is less than USD 450 or GBP 350 and device size is approximately 9 cm × 6 cm × 5 cm. Significance. Experimental neurophysiology often requires significant investment in bulky equipment for specific stimulation requirements, especially when using HFAC block. Different stimulators have limited means of communicating with each other, making protocols more complicated. This device provides an effective solution for multi-channel stimulation and block of nerves, enabling studies on selective neural interfacing in acute scenarios with an affordable, portable and space-saving design for the laboratory. The stimulator can be further upgraded with additional modules to extend functionality while maintaining straightforward programming and integration of functions with one controller. Additionally, all source files including all code and PCB design files are freely available to the community to use and further develop.

Experimental study on electrohydrodynamic flows of a dielectric liquid in a needle-plate configuration under direct/alternating current electric field

Experiments on the electrohydrodynamic (EHD) flow characteristics of a dielectric liquid in a sharp needle-plate configuration under direct current (DC) and alternating current (AC) electric field are carried out. The current-voltage characteristics and the velocity field are simultaneously recorded for understanding the flow behavior and its mechanism. For the DC case, a critical voltage separating the conduction and injection regimes and the corresponding flow reverse is observed. Results indicate the polarity of voltage only influences the flow's intensity in the injection regime. For the AC case, two types of signals with the same 50% duty cycle are considered. For the pulsed voltage (−2.0kV to 0), the flow generally keeps the plume structure and shows weaker strength than the corresponding DC case. For the AC signal (-2.0kV–+2.0kV), the velocity amplitude first decreases and then tends to be constant with the increase of frequency. The weak flow motion with high frequency AC field is due to conduction.

A Low-Cost Programmable High-Frequency AC Electronic Load with Energy Recycling for Battery Module Diagnostics

A low-cost programmable high-frequency alternating current (AC) electronic load for battery module diagnosis which possesses energy recycling and portability is proposed. The proposed AC electronic load consists of a micro-controller, a signal capturing circuit, and a resonant circuit, and can be integrated with a human–machine interface (HMI). To diagnose the dynamic characteristics of a lithium battery module, the proposed AC electronic load is served as a test load for providing a wide-range slew-rate loading function. In this study, the extracted energy from the tested battery module during the diagnostic process can be recycled to save energy. In addition, all of the battery module parameters and test conditions can be preset in the HMI, and the battery characteristics and the recycling rate of the electrical energy also can be estimated. Analysis of operation modes and simulations and some experimental results are used to verify the theoretical predictions.

Transcutaneous high-frequency alternating current for rapid reversible muscle force reduction below pain threshold

Objective. The development of non-invasive, quickly reversible techniques for controlling undesired muscle force production (e.g. spasticity) could expand rehabilitation approaches in those with pathology by increasing the type and intensity of exercises that can be performed. High-frequency alternating current (HFAC) has been previously established as a viable method for blocking neural conduction in peripheral nerves. However, clinical application of HFAC for nerve conduction block is limited due to the invasiveness of surgical procedures and the painful onset response. This study aimed to examine the use of transcutaneous HFAC (tHFAC) at various stimulation frequencies to address these shortfalls. Approach. Ten individuals participated in the study. Surface electrodes were utilized to apply tHFAC (0.5–12 kHz) to the median and ulnar nerves. Individual pain threshold was determined by gradual increase of stimulation amplitude. Subjects then performed a force-matching task by producing grip forces up to the maximal voluntary contraction level with and without application of tHFAC below the pain threshold. Main results. Pain threshold current amplitude increased linearly with stimulation frequency. Statistical analysis showed that both stimulation frequency and charge injected per phase had significant effects (p < 0.05) on grip force reduction. At the group level, application of tHFAC below pain threshold reduced grip force by a maximum of 40.7% ± 8.1%. Baseline grip force trials interspersed between tHFAC trials showed consistent grip force, indicating that fatigue was not a factor in force reduction. Significance. Our results demonstrate the effectiveness of tHFAC at reducing muscle force when applied below the pain threshold, suggesting its potential clinical viability. Future studies are necessary to further elucidate the mechanism of force reduction before clinical application.

High-frequency irreversible electroporation for cardiac ablation using an asymmetrical waveform

BackgroundIrreversible electroporation (IRE) using direct current (DC) is an effective method for the ablation of cardiac tissue. A major drawback of the use of DC-IRE, however, are two problems: requirement of general anesthesia due to severe muscle contractions and the formation of bubbles containing gaseous products from electrolysis. The use of high-frequency alternating current (HF-IRE) is expected to solve both problems, because HF-IRE produces little to no muscle spasms and does not cause electrolysis.MethodsIn the present study, we introduce a novel asymmetric, high-frequency (aHF) waveform for HF-IRE and present the results of a first, small, animal study to test its efficacy.ResultsThe data of the experiments suggest that the aHF waveform creates significantly deeper lesions than a symmetric HF waveform of the same energy and frequency (p = 0.003).ConclusionWe therefore conclude that the use of the aHF enhances the feasibility of the HF-IRE method.

Soleus H-reflex modulation following transcutaneous high- and low-frequency spinal stimulation in healthy volunteers

The main aim of this work was to investigate the difference in the excitability of the soleus H-reflex in healthy volunteers following spinal transcutaneous electrical nerve stimulation (TENS) and high-frequency alternating current (HFAC) at a frequency of 10 kHz applied at the lower thoracic spinal level (T10–T12). A double-blind, randomized, crossover, controlled clinical trial was designed. Participants received three randomized interventions (TENS, 10 kHz, and sham stimulation) during 40 min. The amplitude and latency of the soleus H-reflex were registered prior to, during, and 10 min following stimulation. Twenty-four participants completed the study. A significant inhibition of H-reflex amplitude was observed following transcutaneous spinal TENS (12.7%; 95% CI 1.5–22.2%) when compared with sham stimulation (5.5%; 95% CI 3.6–14.5%; p = 0.03). An increase in H-reflex latency was also observed following transcutaneous spinal stimulation at 10 kHz (2%; 95% CI 1.4–2.5%) as compared with sham stimulation (0.7%; 95% CI 0.07–1.3%; p < 0.01). No differences were found between TENS and 10 kHz for H-reflex modulation. Transcutaneous spinal TENS and HFAC at a frequency of 10 kHz had a modulatory effect on the soleus H-reflex when compared to sham stimulation; however, no differences were found between these two interventions.

The Crucial Role of Nerve Depolarisation in High Frequency Conduction Block in Mammalian Nerves: Simulation Study.

Neurostimulations which use High Frequency Alternating Current (HFAC) block show great promise for neuromodulatory therapies. Treatments have been developed for various health conditions including obesity and obesity related health risks, and now even stomach cancer treatments are being considered. However the mechanism of the block is still not completely clear, as well as how various neural and electrode parameters affect it. In order to study conduction block during HF stimulation in mammalian axons, we describe a detailed computational model and perform comprehensive simulations. We establish relationships between the blocking frequency and amplitude versus fibre diameter and the distance between the electrode and fibre. We found that only a certain level of depolarisation will universally create a block irrespective of the fibre size, and it is in the range 24-30mV depending on the stimulus frequency. Our study crucially improves our knowledge about this important technique which is rapidly emerging as a commercially available therapy.

Structure and magnetic properties of Co-Ni-Mn alloy coatings (part 2)

Using the method of high-frequency alternating current (HFAC), based on the preliminary model forecasting of the ratio of metal ions in the electrolyte and the phase composition of the coating, Co-Ni-Mn alloy precipitates with the specified magnetic properties are obtained. It is shown that precipitation with a hexagonal close-packed α-Co phase has the highest coercive force. The presence of a free phase in a small amount (2.1 - 2.6% of weight) of Mn increases the ferromagnetic properties of films due to the domain structures with a poorly defecting α-Mn crystal lattice. The adjustable amount of the amorphous Co(OH)2 phase provides the nanostructure dimensions of the crystals.