Pulsed Magnetic Field Research Articles

Case report: Association of laser and magnetotherapy with iPRF for treatment of herniated disc

Lumbar disc herniation is one of the main causes of pain and disability, affecting 1% to 5% of the adult population, especially between 30 and 50 years of age. Conservative treatments include corticosteroids, anti-inflammatories, and physical therapy, with surgery being reserved for refractory cases. Surgical complications are possible, including pain and neurological sequelae. This study presents the clinical case of an extrusive disc herniation in a 49-year-old patient, treated with orthobiologicals (iPRF), superpulsed laser and pulsed magnetic field, resulting in symptom improvement and total remission of the hernial process confirmed by Magnetic Resonance Imaging. The association between a minimally invasive approach proved to be effective, suggesting the feasibility of using combined therapies to treat disc herniations with remarkable clinical improvement in two months, without surgical risks and hospital costs. The synergy between iPRF, superpulsed laser, and pulsed magnetotherapy promotes cell recovery and inflammatory modulation.

Radiofrequency Electromagnetic and Pulsed Magnetic Fields Protected the Kidney Against Lipopolysaccharide-Induced Acute Systemic Inflammation, Oxidative Stress, and Apoptosis by Regulating the IL-6/HIF1α/eNOS and Bcl2/Bax/Cas-9 Pathways

Background/Objectives: Sepsis-associated acute kidney injury caused by lipopolysaccharide (LPS) is related to hypoxia, amplification of the inflammatory response, oxidative stress, mitochondrial dysfunction, and apoptosis. This study aims to explore the protective effects of a radiofrequency electromagnetic field (RF-EMF) and a pulsed magnetic field (PMF) on acute kidney injury in rats. Materials and methods: Forty female Wistar albino rats were randomly divided into five groups (each containing eight rats): control, LPS, RF-EMF, PMF, and RF-EMF + PMF groups. Six hours after LPS application, blood and tissues were removed for histopathological, immunohistochemical, biochemical, and genetic analysis. Results: Histopathological findings, caspase-3, inducible nitric oxide synthase and tumor necrosis factor-alpha immunoexpressions, total oxidant status and oxidative stress index levels, and interleukin-6, hypoxia-inducible factor alpha, Bcl-2-associated X protein, and caspase 9 gene expression in kidney tissue and blood urine nitrogen and creatinine levels in blood were increased, whereas endothelial nitric oxide synthase and B-cell lymphoma 2 gene expression were decreased in the LPS groups. Both RF-EMF and PMF reversed all these findings and recovered renal tissues. Conclusions: Noninvasive, nontoxic, low-cost PMF and RF-EMF, both single and combined, have been demonstrated to have renoprotective anti-inflammatory, antioxidant, and antiapoptotic effects.

Magnetocaloric effect in La1−zCez(Fe0.88−yMnySi0.12)13 with tunable, low transition temperature in high magnetic fields

Cryogenic magnetic refrigeration becomes more and more important nowadays, especially for the liquefaction of gases such as hydrogen. In this study, we have synthesized La1−zCez(Fe0.88−yMnySi0.12)13 samples and investigated their magnetic and magnetocaloric properties in order to assess their potential for cryogenic applications. By adjusting the Mn and Ce content and adding excess rare-earth elements, the first-order ferromagnetic transition was lowered from 200 to 40 K and the adiabatic temperature change of the samples was measured directly using pulsed magnetic fields. The sample with the lowest transition temperature still showed a significant adiabatic temperature change in magnetic fields up to 10 T, with an increasingly stronger first-order transition observed in samples with higher Ce substitution. In addition, we synthesized spherical powder with diameters between 20 and 120 μm using ultrasonic atomization while maintaining the magnetic transition, which is a promising starting material for future additive manufacturing of magnetocaloric materials.

Spike-timing-dependent-plasticity learning in a planar magnetic domain wall artificial synapse

Abstract Future neuromorphic architectures will require millions of artificial synapses, making understanding the physical mechanisms behind their plasticity functionalities mandatory. In this work, we propose a simplified spin memristor, where the resistance can be controlled by magnetic field pulses, based on a Co/Pt multilayer with perpendicular magnetic anisotropy as a synapsis emulator. We demonstrate plasticity and spike time dependence plasticity (STDP) in this device and explored the underlying magnetic mechanisms using Kerr microscopy imaging and Hall magneto-transport measurements. A well-defined threshold for magnetization reversal and the continuous resistance states associated with the micromagnetic configuration are the basic properties allowing plasticity and STDP learning mechanisms in this device.

Field switching of microfabricated metamagnetic FeRh MRI contrast agents

In a step towards generating switchable MRI cellular labels, we demonstrate in-situ field switching of micron scale metamagnetic Iron-Rhodium (FeRh) thin film particles. A thin-film (200 nm) FeRh sample was fabricated and patterned into an array of progressively smaller squares with sizes ranging from 500 μm down to 1 μm. The large first order phase change from antiferromagnetic to ferromagnetic state was characterized using vibrating sample magnetometry, magnetic force microscopy, and MRI. Room temperature MRI experiments sensitive to the local magnetic field surrounding the particles demonstrated the low moment state (OFF MRI contrast) at 4.7T and high moment state (ON MRI contrast) at 11.7T for the array where sizes down to 2–3 μm were observed in MRI at 50 μm resolution. The expected temperature dependent MRI contrast change was seen at 4.7T, where 10 μm particles could be observed at 150 μm resolution in the ON state. A shielded MRI insert, used to temporarily increase or decrease the magnetic field up to 0.77T amplitude, was used to reversibly switch the particle array at constant temperature and blink the particles ON and OFF at 4.7T. This work demonstrates the MRI contrast switching potential for FeRh particles with biological cell dimensions, and the use of magnetic field pulses for reversible MRI label contrast control.

Symmetry-governed dynamics of magnetic skyrmions under field pulses

Topological magnetic solitons, such as skyrmions, exhibit intriguing particle-like properties that make them attractive for fundamental research and practical applications. While many magnetic systems can host skyrmions as statically stable configurations, chiral magnets stand out for their ability to accommodate a wide diversity of skyrmions with arbitrary topological charges and varied morphologies. Despite extensive investigation, a complete understanding of chiral magnetic skyrmions has remained elusive. We present a classification of all chiral skyrmions, demonstrating three classes based on their response to external magnetic field pulses: stationary, translating, and rotating. We highlight the role of magnetic texture symmetry in this classification. Skyrmions with varied dynamics offer avenues for exploring phenomena like skyrmion-skyrmion scattering that might be crucial for future applications.

Optimisation and loss analyses of pulsed field magnetisation in a superconducting motor with cryocooled iron cores

Optimisation and loss analyses of pulsed field magnetisation in a superconducting motor with cryocooled iron cores

Multicaloric effect in FeRh, exploiting the thermal hysteresis in a multi-stimuli cycle combining pulsed magnetic field and uniaxial load

Large magnetocaloric effects can be observed in materials with first-order magneto-structural phase transition. However, materials with large thermal hysteresis show a reduced effect in moderate fields (∼2 T) because the external field is insufficient to induce a fully reversible transformation. The hysteresis can be overcome or even exploited by applying a second external stimulus. A multi-stimuli test bench has been built to demonstrate the multicaloric effect in FeRh alloy using a pulsed magnetic field up to 9 T and a uniaxial stress of up to 700 MPa. A cyclic multicaloric effect of ±2.5 K could be observed for a sequential application of a pulsed field of 3 T and a uniaxial stress of 700 MPa. The interplay among external field strength, thermal hysteresis, and the transition width enables the use of pulsed magnetic fields and allows a decoupling of the applied magnetic field and the heat transfer process in the multi-stimuli cycle.

A novel pulse-current waveform circuit for low-energy consumption and low-noise transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) is widely used for the noninvasive activation of neurons in the human brain. It utilizes a pulsed magnetic field to induce electric pulses that act on the central nervous system, altering the membrane potential of nerve cells in the cerebral cortex to treat certain mental diseases. However, the effectiveness of TMS can be compromised by significant heat generation and the clicking noise produced by the pulse in the TMS coil. This study proposes a novel, non-resonant, high-frequency switching design controlled by high-frequency pulse-width modulation (PWM) voltage excitation to achieve ideal pulse-current waveforms that minimize both clicking noise and heat generation from the TMS coil. First, a particle swarm optimization algorithm was used to optimize the pulse-current waveform, minimizing both the resistance loss and clicking noise (vibration energy) generated by the TMS coils. Next, the pulse-current waveform was modeled based on the principles of programmable transcranial magnetic stimulation circuits. The relationships between the parameters of the pulse-current waveform, vibration energy, and ohmic resistance loss in the TMS coil were explored, ensuring the necessary depolarization of the nerve membrane potential. Finally, four insulated-gate bipolar transistors, controlled by a series of PWM pulse sequences, generated the desired pulse-current duration and direction in the H-bridge circuit. The duration and slope of the rising and falling segments of the current waveform were adjusted by the PWM pulse duration. The optimized current waveform, represented by three segmented functions, reduces heat loss and noise while inducing a greater change in neural membrane potential compared with those obtained with conventional symmetric waveforms. Spectral analysis further confirmed that the noise spectrum of the optimized current waveform, particularly the peak spectrum, is significantly lower than that of the conventional triangular symmetric waveform. The study provide a method and new ideas for low energy consumption and low-noise transcranial magnetic stimulation by using TMS circuit design techniques as well as waveform optimization.

Fast barrier-free switching in synthetic antiferromagnets

We analytically solve the Landau-Lifshitz equations for the collective magnetization dynamics in a synthetic antiferromagnet (SAF) nanoparticle and uncover a regime of barrier-free switching under a short small-amplitude magnetic field pulse applied perpendicular to the SAF plane. We give examples of specific implementations for forming such low-power and ultra-fast switching pulses. For fully optical, resonant, barrier-free SAF switching we estimate the power per write operation to be ∼100 pJ, 10–100 times smaller than for conventional quasi-static rotation, which should be attractive for memory applications.

A fluidic device for continuous on-line inductive sensing of proteolytic cleavages.

Proteases, an important class of enzymes that cleave proteins and peptides, carry a wealth of potentially useful information. Devices to enable routine and cost effective measurement of their activity could find frequent use in clinical settings for medical diagnostics, as well as some industrial contexts such as detecting on-line biological contamination. In particular, devices that make use of readouts involving magnetic particles may offer distinct advantages for continuous sensing because material they release can be magnetically captured downstream and their readout is insensitive to optical properties of the sample. Bioassays based on giant magnetoresistance sensors that detect the binding or release of magnetic materials have been widely explored for these reasons, but they typically require expensive consumables. Here, we develop a simpler protease sensor based on inductive detection of particle release with pulsed magnetic fields, leveraging a design that incorporates both the pulse coil and gradiometer coils into a printed circuit board. Our fluidic chips are formed from casts of 3D printed molds, such that both the sensor and the consumable components could be relatively easy to mass produce. Using pulses ranging up to 10 s of mT, we show that our device has a limit of detection below 1 μg of iron and that its duty cycle can be varied to control temperature through Joule heating. By chemically functionalizing the glass surface of our fluidic chips with zwitterionic polymer and incorporating a PEG block co-polymer into the PDMS component, we are able to suppress the nonspecific binding of albumin by 7.8 times inside the chips. We demonstrate a layer-by-layer approach for covalently linking magnetic nanoparticles to the chips via cleavable peptide substrates. Finally, we observe the release of the magnetic particles from the chips under conditions of proteolytic cleavage and measure resulting changes in inductive signals, demonstrating a detection sensitivity for chymotrypsin in the hundreds of nM. The methods we establish here have the potential to aid progress toward sensors comprised of disposable fluidic chips measured by inexpensive detection devices that may one day facilitate ubiquitous protease activity monitoring.

Early intervention using long-term rhythmic pulsed magnetic stimulation alleviates cognitive decline in a 5xFAD mouse model of Alzheimer's disease

BackgroundAlzheimer's disease (AD) is the most prevalent form of dementia, but no effective therapeutic strategy is available to date. Rhythmic magnetic stimulation is an attractive means of neuron modulation that could be beneficial for restoring learning and memory abilities. ObjectiveTo assess the effect of a compound pulsed rhythmic magnetic field (cPMF) on cognition during AD progression and to explore the appropriate cPMF intervention period. MethodsFemale 5xFAD mice aged 10 weeks and 18 weeks were exposed to cPMF with a carrier frequency of 40 Hz, repeated at 5 Hz for 1 h/d for 8 consecutive weeks. The Morris water maze (MWM) test was used for cognitive behavioral assessment. Furthermore, changes in molecular pathology within the brain were detected using immunofluorescence staining and real-time PCR. Results10-week-old AD mice treated with cPMF explored the target quadrant more frequently than sham-exposed AD mice in MWM test, exhibiting improved learning and memory abilities. Additionally, cPMF exposure alleviated Aβ plaque deposition and astrogliosis in the AD brain. Moreover, neurotrophic factor fibroblast growth factor 1 (FGF1) in the AD brain was upregulated by cPMF treatment. However, in 18-week-old AD mice treated with cPMF, cognitive performance and Fgf1 gene expression were not significantly improved, although Aβ plaque deposition and astrogliosis were alleviated. ConclusionEarly intervention via long-term rhythmic cPMF stimulation may alleviate the histopathological features and enhance neuroprotective gene Fgf1 expression, thereby improving the cognitive performance of 5xFAD mice, which should provide promising insight for the clinical treatment of patients with AD.

Effect of rare earth and differential low frequency pulsed magnetic field on hot cracking tendency of large-scale ZK61 alloy ingots

Effect of rare earth and differential low frequency pulsed magnetic field on hot cracking tendency of large-scale ZK61 alloy ingots

Supercapacitor-based pulse generator with waveform adjustment capability for small animal transcranial magnetic stimulation

In transcranial magnetic stimulation (TMS), pulsed magnetic fields are applied to the brain, typically requiring high-power stimulators with high voltages and low series impedance. TMS pulse generators for small animal coils, are underexplored, with limited dedicated circuits and simulation models. Here, we present a new design for a high-power TMS pulse generator for small animals, utilizing a pre-charged supercapacitor that is sufficient to produce repeated pulses for TMS applications without the need for recharging. This approach eliminates the need for expensive high-voltage components and a high-voltage power supply. In this paper, we detail the design approach and basic block diagrams of a supercapacitor (SC) based TMS pulse generator, along with its experimental results. The findings indicate that the new circuit enables a complete test using just a single charge of an SC module. The proposed circuit functions as a versatile pulse-shaping device, where the MOSFET is treated as a dynamically varying resistor element rather than a traditional switch; allowing pulse parameter variations. We analyze a novel circuit for generating and controlling TMS pulses in small animal coils, and demonstrate its effectiveness through experimental results.

Study of the Mechanism of Biological Activity Enhancement of Benzylpenicillin Sodium Salt after Treatment with Pulsed Magnetic Field of High Intensity

Magnetic field is able to change the biological activity of drugs, which can be used in medicine. Literature data on the increase in biological activity of prepared drugs under the influence of pulsed magnetic fields immediately before their administration have not been found. This article presents data on the increase in antibacterial activity of benzylpenicillin sodium salt after its treatment with pulsed magnetic field. The aim of the work is to investigate the reasons for the increase in biological activity of benzylpenicillin, to show the changes that occur in the molecule under the influence of a pulsed magnetic field. Exposure to magnetic field was carried out on powdered antibiotic on magnetic-pulse unit with magnetic field strength H = (0.09÷0.82) × 106 A/m. The pulse shape was a damped sinusoid with frequency response f = 40 kHz and f = 51 kHz. Experimental methods of NMR-spectroscopy and IR-Fourier-spectroscopy were used in the studies. The shift in the value of chemical shifts (δH) and spin-spin interaction constants (2JHH) of the signals of methylene protons of the benzyl substituent as a result of the magnetic field was found. The changes in the absorption bands of the N–H and C=O bonds of the amide grouping and the carbonyl group of the lactam cycle were detected by FTIR spectroscopy. The obtained spectral data allow us to conclude that the geometry of the benzylpenicillin sodium salt molecule in the amide fragment has changed under the influence of a pulsed magnetic field, which is probably the reason for the increase in antibacterial activity of the antibiotic.

Investigation effect of pulsed magnetic fields on pepper (Capsicum annuum L.) plant growth

Pepper (Capsicum annuum L.) plants are extensively utilized in culinary and spice industries, rendering their cultivation pivotal in agricultural production. Enhancing their growth and yield is a critical research area for producers and horticulturists. Recent investigations have delved into the use of pulsed magnetic fields (PMFs) as a potential growth stimulant. Unlike static magnetic fields, PMFs are characterized by transient, high-intensity magnetic bursts, potentially eliciting varied responses in plants. To assess PMFs' impact on pepper plants, several experiments were setup comprising two solenoids, each wound around an 18-cm-diameter rigid plastic pipe but with differing coil turns, one with 40 and the other with 80 turns. These solenoids were utilized to generate PMFs at a frequency of 1 kHz with two intensities: 17 micro-Tesla (µT) and 34 µT. The pepper plants were situated within the PMF zone under controlled conditions, ensuring consistency in light, temperature, and moisture levels. The experimental design included three plant groups: a control group with no PMFs exposure except that of the Earth’s magnetic field, and two groups subjected to 17 µT and 34 µT PMFs intensities with Earth’s magnetic field, ranging between 25-65 µT. The treatment spanned 15 days, involving 6 hours of daily continuous exposure. Key growth indicators such as plant height, stem diameter, leaf area, and fresh and dry weights of both shoot and root systems were measured and analyzed. This analysis revealed significant increases in plant height, leaf area, and fresh and dry weights of the shoot, but not in root systems. Further research is warranted to deepen the understanding of PMFs' effects on pepper plants.

Three‐dimensional modeling of electromagnetic field and fluid flow during solidification of an aluminum alloy in a pulsed magnetic field

AbstractThree‐dimensional finite element models were built to describe the distribution of electromagnetic fields and fluid fields under a low frequency low voltage time‐dependent pulsed magnetic field. The simulation results showed that eddy current circling around the axis of the melt can be induced by pulsed magnetic field. Periodic positive‐negative Lorentz force in the melt was induced from the interaction between the current and magnetic field. The effects generated by the pulsed magnetic field included vibration, fluid flow and Joule heat. The melt flowed in the form of a multi‐circle and the fluid velocity was composed of a base component and a pulse component. The temperature in the melt was homogeneous because of the fluid flow. Melt temperatures were measured and compared with the simulated results during solidification process of aluminum alloy A356 (Al−Si alloy), which qualitatively confirmed the decrease of temperature gradient. Moreover, the effects of material resistivity and electromagnetic parameters of the pulsed magnetic field were investigated. Materials with smaller resistivity took larger electromagnetic force. The fluid flowed much faster under larger excitation current density and frequency. Finally, the grain refinement mechanisms under the pulsed magnetic field were analyzed.

Numerical simulation on metallurgical transport phenomena during DC casting of large-size Mg-Gd-Y alloy billet under various magnetic fields

The manufacture of large-size rare-earth Magnesium alloy billets by direct-chill (DC) casting process is now facing great technical challenges, mainly due to the high cost of casting experiments, and such casting defects like severe cracking, macrosegregation, and non-homogenized solidified structure. Based on the low-cost and high-efficiency numerical simulation method, the present study systematically explores the effects of single pulsed and alternating magnetic fields (PMF and AMF), differential-phase pulsed and alternating magnetic fields (DPMF and DAMF) on DC casting metallurgical transport phenomena of Φ750mm large-size Mg-Gd-Y magnesium alloy billet. The electromagnetic characteristics, flow behavior, and temperature distribution during casting process are clearly visualized. The results demonstrate that traditional DC casting process is optimized by applying magnetic fields. For one thing, pulsed magnetic fields (PMF and DPMF) generate larger and faster changing instantaneous Lorentz forces, which induce huge transient impact and oscillation effects on the melt. For another, alternating magnetic fields (AMF and DAMF) have greater time-average Lorentz forces, which can force the melt to flow continuously and steadily. Additionally, differential-phase magnetic fields (DPMF and DAMF) enhance the melt’s axial flow strength while reducing the small vortex generated at the edges, resulting in improved heat transfer efficiency and uniform temperature field. Among those magnetic fields, DPMF shows dual advantages of transient oscillation and homogenized temperature distribution. Based on the present simulated research, the Φ750mm large-sized rare earth Mg-Gd-Y alloy billet with high-quality and non-cracking has been manufactured during DC casting process under DPMF.

Metamagnetic transition behaviors and dissipation energy at low temperatures of (Ni–Co)50–Mn–Sn alloys under pulsed high magnetic fields

Metamagnetic transition behaviors and dissipation energy at low temperatures of (Ni–Co)50–Mn–Sn alloys under pulsed high magnetic fields

Study on the Microstructure and Properties of Al Alloy/Steel CMT Welding–Brazing Joints Under Different Pulse Magnetic Field Intensities

Butt welding experiments on 6061 Al alloy and Q235B steel of 2 mm thickness were conducted using an ER4047F flux-cored wire as the filler metal, after adding a pulsed magnetic field into the process of cold metal transfer (CMT) welding. The effect of the pulsed magnetic field intensity on the macro morphology, microstructure, tensile strength and corrosion resistance of the welding–brazing joint was analyzed. The results showed that when the pulsed magnetic field intensity increased from 0 to 60 mT, the wettability and spreadability of the liquid metal were improved. As a result, the appearance of the Al alloy/steel joint was nice. However, when the pulsed magnetic field intensity was 80 mT, the stability of the arc and the forming quality of the joint decreased, which resulted in a deterioration in the appearance of the joint. A pulsed magnetic field with different intensities did not alter the microstructure of the joint. All of the joint was composed of θ-Fe2(Al,Si)5 and τ5-Al7.2Fe1.8Si at the interface and Al-Si eutectic phase and α-Al solid solution at the weld seam zone. Actually, with the pulsed magnetic field intensity increasing from 0 mT to 60 mT, the IMC thickness in the interfacial layer gradually reduced under the action of electromagnetic stirring. Also, the grain in the weld seam was refined, and elements were distributed uniformly. But when the pulsed magnetic field intensity was 80 mT, the grain in the weld seam began to coarsen, and the intermetallic compound (IMC) thickness was too small, which was unfavorable for the metallurgical bonding of Al alloy and steel. Therefore, with the increase in pulsed magnetic field intensity, the tensile strength of the joints first increased and then decreased, and it reached its maximum of 187.7 MPa with a pulsed magnetic field intensity of 60 mT. Similarly, the corrosion resistance of the joint first increased and then decreased, and it was best when the pulse magnetic field intensity was 60 mT. The Nyquist plot and Bode plot confirmed this result. The addition of a pulsed magnetic field caused less fluctuation in the anode current density, resulting in less localized corrosion of the joint using the scanning vibrating electrode technique (SVET). The XPS analysis showed the Al-Fe-Si compounds replacing the Fe-Al compounds in the joint was the main reason for improving its corrosion resistance under the action of a pulsed magnetic field.