Pulsed Magnetic Field Research Articles

Rapid label-free impedimetric detection of progesterone enhanced by immunomagnetic bead-based competitive immunoreaction

Detecting progesterone (P4) concentration in cow serum is essential for monitoring the pregnancy progress after fertilization and is significant for the dairy farming industry and veterinary medicine. This study reports enzyme-free immunomagnetic beads (IMBs)-based competitive immunoassay for detecting P4 by P4-bovine serum albumin (BSA)-modified biosensors. The anti-P4 antibody-conjugated IMBs serve as collectors to capture P4 in undiluted serum samples to prevent the biosensor surface from biosample contamination and as insulated labels to report the electron-transfer resistance signal of electrochemical impedance spectroscopy (EIS) measurement. The IMBs and P4-containing samples were mixed for 15−30 min, capable of obtaining stable P4@IMB complexes. The 0.2-kGauss pulsed magnetic field (PMF) of the 20-s pulse width and 20-s relaxation time applied for 5 min can shorten the immunoreaction time between the P4@IMBs and the P4-BSA-modified biosensor and reduce the IMB's nonspecific adsorption on the biosensor surface. This competitive immunoassay's cut-off value and detection limit were 7.71 ng/mL and 7.33 ng/mL, respectively, which is lower than the serum's P4 plateau concentration (over 8 ng/mL) of dairy cows on days 6–16 of estrus cycles and that in pregnancy. The IMB-based immunoassay combining the PMF attraction and the label-free EIS measurement exhibits promising potential for rapidly detecting P4 in undiluted serum.

Development of Multi-Part Field-Shapers for Magnetic Pulse Welding Using Nanostructured Cu-Nb Composite

Magnetic pulse welding (MPW) employs a strong pulsed magnetic field to accelerate parts against each other, thus forming an impact joint. Single-turn tool coils and field-shapers (FSs) used in MPW operate under the most demanding conditions, such as magnetic fields of 40–50 T with periods lasting tens of microseconds. With the use of conventional copper and bronze coils, intense thermo-mechanical stresses lead to the rapid degradation of the working bore. This work aimed to improve the efficiency of field-shapers and focused on the development of two- and four-slit FSs with a nanocomposite Cu 18Nb brazed wire acting as an inner current-carrying layer. The measured ratios of the magnetic field to the discharge current were 56.3 and 50.6 T/MA for the two- and four-slit FSs, respectively. FEM calculations of the magnetic field generated showed variations of 6–9% and 3% for the two- and four-slit FSs, respectively. The ovality percentages following copper tube compression were 27% and 7% for the two- and four-slit FSs, respectively. The measured deviations in the weld-joining length were 11% and 1.4% in the two- and four-slit FSs, respectively. Compared to the previous experiments on an entirely steel inductor, the novel FS showed significantly better results in terms of its efficiency and the homogeneity of its magnetic field.

Stroboscopic time-of-flight neutron diffraction in long pulsed magnetic fields

We present proof-of-principle experiments of stroboscopic time-of-flight (TOF) neutron diffraction in long pulsed magnetic fields. By utilizing electric double-layer capacitors, we developed a long pulsed magnet for neutron diffraction measurements, which generates pulsed magnetic fields with the full widths at half maximum of >102 ms. The field variation is slow enough to be approximated as a steady field within the time scale of a polychromatic neutron pulse passing through a sample placed in a distance of the order of 101 m from the neutron source. This enables us to efficiently explore the reciprocal space using a wide range of neutron wavelength in high magnetic fields. We applied this technique to investigate field-induced magnetic phases in the triangular lattice antiferromagnets CuFe1−xGaxO2 (x=0,0.035). Published by the American Physical Society 2024

Моделирование помех в электронном устройстве при воздействии импульсного магнитного поля с использованием искусственной нейронной сети

Modern electronic means are quite sensitive to electromagnetic interference. At the same time, they must function reliably in the existing electromagnetic environment. Lightning discharges and industrial sources make a significant contribution to the formation of the electromagnetic environment around electronic equipment. In this case, pulsed magnetic fields with microsecond parameters most often arise. The most rational approach to ensuring electromagnetic compatibility of electronic means is the most complete accounting and protection from possible phenomena at the design stage. Different methods for modeling the consequences of exposure to electromagnetic interference have their own advantages and disadvantages. To develop a technique and modeling interference in electronic means based on an artificial neural network using the example of the influence of a pulsed magnetic field a the purpose of this work. A practical technique for calculation the magnitude of interference in electronic means using an artificial neural network the paper proposes. All stages of the technique are described: analysis of the main input parameters affecting the amount of interference in the electronic means; the use of a special experimental stand for measuring interference depending on significant input parameters; choosing the structure and parameters of an artificial neural network to modeling interference; choosing a training method for an artificial neural network; choosing a criterion for assessing the quality of training when solving a regression problem; normalization of training data; training an artificial neural network using measured data; modeling the amount of interference in the communication line of an electronic means when exposed to a pulsed magnetic field; assessment of consequences and selection of methods of protection against interference. As an example, we consider the problem of modeling the amount of interference in a communication line inside an electronic means when exposed to a pulsed magnetic field. The magnetic field has parameters recommended by the requirements of the regulatory document on electromagnetic compatibility of devices. In the problem under consideration, an acceptable discrepancy in results is achieved with an acceptable number of neural network training epochs.

Pulse Field Magnetization (PFM) With Different HTS Stacked Tape Architecture for Electrical Machine

Pulse Field Magnetization (PFM) With Different HTS Stacked Tape Architecture for Electrical Machine

Pulse Field Magnetization of GdBCO Without Rapid Decrease in Magnetic Flux Density

Pulse Field Magnetization of GdBCO Without Rapid Decrease in Magnetic Flux Density

Optical magnetic field enhancement using ultrafast azimuthally polarized laser beams and tailored metallic nanoantennas

Structured light provides unique opportunities to spatially tailor the electromagnetic field of laser beams. These include the possibility of a sub-wavelength spatial separation of their electric and magnetic fields, which would allow isolating interactions of matter with pure magnetic (or electric) fields. This could be particularly interesting in molecular spectroscopy, as excitations due to electric and—usually very weak—magnetic transition dipole moments can be disentangled. In this work, we show that the use of tailored metallic nanoantennas drastically enhances the strength of the longitudinal magnetic field carried by an ultrafast azimuthally polarized beam (by a factor of ∼65), which is spatially separated from the electric field by the beam’s symmetry. Such enhancement is due to favorable phase-matching of the magnetic field induced by the electric current loops created in the antennas. Our particle-in-cell simulation results demonstrate that the interactions of moderately intense (∼1011 W/cm2) and ultrafast azimuthally polarized laser beams with conical, parabolic, Gaussian, or logarithmic metallic nanoantennas provide spatially isolated magnetic field pulses of several tens of Tesla.

Driving Inertial Confinement Fusion With Strong Pulsed Magnetic Field

Regarding inertial confinement fusion (ICF), the current proposed driving energy sources are mainly laser beams or high-energy particle beams. This paper proposes a new method: Adopting a strong pulsed magnetic field as the driving energy source, explored its action principle, derived all relevant formulas, calculated an example and compared it with existing driving methods.The conclusion drawn is that this method can achieve high energy gain, the required equipment is relatively simple and without the disadvantages of other methods, making it a feasible method.

Feature Matching of Microsecond-Pulsed Magnetic Fields Combined with Fe3O4 Particles for Killing A375 Melanoma Cells.

The combination of magnetic fields and magnetic nanoparticles (MNPs) to kill cancer cells by magneto-mechanical force represents a novel therapy, offering advantages such as non-invasiveness, among others. Pulsed magnetic fields (PMFs) hold promise for application in this therapy due to advantages such as easily adjustable parameters; however, they suffer from the drawback of narrow pulse width. In order to fully exploit the potential of PMFs and MNPs in this therapy, while maximizing therapeutic efficacy within the constraints of the narrow pulse width, a feature-matching theory is proposed, encompassing the matching of three aspects: (1) MNP volume and critical volume of Brownian relaxation, (2) relaxation time and pulse width, and (3) MNP shape and the intermittence of PMF. In the theory, a microsecond-PMF generator was developed, and four kinds of MNPs were selected for in vitro cell experiments. The results demonstrate that the killing rate of the experimental group meeting the requirements of the theory is at least 18% higher than the control group. This validates the accuracy of our theory and provides valuable guidance for the further application of PMFs in this therapy.

Understanding Ion Dynamics in Closoborate-Type Lithium-Ion Conductors on Different Time-Scales.

The lithium-ion transport mechanism in 0.7Li(CB9H10)-0.3Li(CB11H12) complex hydride solid electrolyte was studied over a wide time-scale (ns-ms) by choosing appropriate techniques for assessing ionic motion on the desired time-scale using nuclear magnetic resonance (NMR) relaxation, AC impedance, and pulsed field gradient-NMR (PFG-NMR) measurements. The 7Li NMR line width decreased with increasing temperature, and the spin-lattice relaxation time T1 for the cation and anions showed a minimum near 303 K, indicating that the lithium ions and the anions were highly mobile. The activation energy estimated from the analysis of the NMR relaxation time matched well with the values estimated from the AC impedance and PFG-NMR. This confirms that the lithium-ion motion in 0.7Li(CB9H10)-0.3Li(CB11H12) is the same over a wide time-scale, suggesting steady Li-ion motion over a wide transport range. This understanding offers insights into strategies for designing complex hydride lithium superionic conductors.

Sublimed fine-grained dysprosium: Significant magnetocaloric effect

As is known, rare-earth metals (REMs) are promising magnetocaloric materials. The magnitude of the magnetocaloric effect (MCE) of REMs significantly depends on their purity. This paper presents results of studies of the magnetic and magnetocaloric properties of sublimed dysprosium, prepared in the course of the present study, with an emphasis on its impurity and structure perfection. The comprehensive analysis of the chemical composition of sublimed dysprosium, which was performed for the first time by atom probe tomography, showed that the metal corresponds to high-purity rare-earth metals (3 N+). The MCE effect was studied using direct measurements of the adiabatic temperature change (ΔTad) in pulsed (up to 50 T) and steady (up to 14 T) magnetic fields. The studies of the MCE of polycrystalline sublimed Dy by direct method showed that the high ΔTad value for sublimed Dy are comparable with those obtained for single-crystal Dy in magnetic fields up to 5 T. The vacuum sublimation, which is more economical and technologically advanced in contrast to single crystal growing, can be used to create magnetocaloric REM-based materials with high MCE values.

Effect of grain motion and Joule heat on grain refinement under a pulsed magnetic field

Taking industrial pure aluminum as the research object, the melt flow rate of the aluminum is controlled by the layered casting method, and the influence of the change in electromagnetic parameters on the melt flow rate is balanced. By combining numerical simulations, solidification experiments and theoretical analysis, the joint effects of grain movement and Joule heat are investigated. The results show that an increase in the distance of grain motion facilitates grain crossing of the boundary layer and promotes grain refinement; moreover, the Joule heat generated during the action of the pulsed magnetic field inhibits the formation of grains. In this paper, the phenomenon of grain coarsening under a large pulsed magnetic field is quantitatively analyzed through the synergistic mechanism of grain motion and Joule heat.

Unusual metallic state in superconducting A15-type La4H23

Abstract Hydride superconductors continue to fascinate the communities of condensed matter physics and material sciences because they host the promising room-temperature superconductivity. The current research has been concentrated on the new hydride superconductors with the enhancement of the superconducting transition temperature (Tc). The multiple extreme conditions (high pressure/temperature and magnetic field) will introduce new insights on the hydride superconductors. The study of transport properties under very high magnetic fields facilitates the understanding of the superconductivity in the conventional hydride superconductors. In the present work, we report experimental evidence of an unusual metal state in a newly synthesized cubic A15-type La4H23 that exhibits superconductivity with a Tc reaching 105 K at 118 GPa. A large negative magnetoresistance is observed for strong pulsed magnetic fields in the non-superconducting state below 40 K. Moreover, we construct the full magnetic phase diagram of La4H23 up to 68 T at high pressure. The present work reveals anomalous electronic structural properties of A15-La4H23 under high magnetic fields, therefore holding great importance for advancing the understanding of quantum transport behaviors in hydride superconductors.

Well balanced pick-up assembly for double pulsed magnetic field apparatus

The generation of high magnetic pulsed fields involves several technological challenges. State-of-the-art field peak intensities can be achieved by means of double-coil systems and, as for other configurations, a special pick-up system is required to clean the signal from spurious components and artifacts. However, the design of a well-balanced pick-up for double-coil systems is not a trivial task because of the different mutual inductance of the two field coils. In general the pick-up can be optimized for one coil only, but not for both. Here we present a new pick-up concept specifically aimed at solving this problem, based on an active compensation bridge and a special compensating coil located outside field-generating coils. Besides yielding a good balance of the signal over all pulse duration, a further advantage is an additional increase in the signal-to-noise ratio.

Transcranial Magnetic Stimulation-induced Mania: A Risk Worth Taking?

Introduction In the context of treatment-resistant bipolar depression, the use of neuromodulation techniques, notably transcranial magnetic stimulation (TMS), has been on the rise, particularly in the treatment of mood disorders. TMS involves the generation of a strong pulsed magnetic field through an electromagnet placed near the skull, thereby inducing an electrical field capable of depolarizing nerve cell membranes (Dolberg et al., 2001). The magnetic nature of TMS carries advantages compared to direct electric stimulation, such as fewer side effects, reduced invasiveness, and precise targeting. Nevertheless, it is not without its risks. Reported concerns include the induction of manic or hypomanic states, particularly in individuals with bipolar disorder, as well as unipolar depression (Sakkas et al., 2003; Ozten et al.,2013; Knox et al 2021).Objectives This review aims to assess the safety and viability of TMS as a therapeutic option and how to best optimize its clinical use.MethodsA comprehensive literature review was conducted utilizing resources from Pubmed, Researchgate, and Google Scholar.ResultsDespite some inconsistencies and potential confounding factors, our findings suggest that TMS may not significantly elevate the risk of manic switching, especially when compared to conventional treatments like antidepressants. However, it may potentially induce manic episodes, particularly when used as monotherapy or in combination with other treatments. Variables such as treatment protocol and prior response to medication may contribute to mood switching risk. Proposed safety measures include personalized protocol design, close patient monitoring and the combination with mood-stabilizing medication.ConclusionsTranscranial magnetic stimulation has been associated with manic and hypomanic episodes in mood disorder patients. While the evidence remains limited, it appears that certain individuals may be more susceptible to mood switching. Nevertheless, further research is needed to better elucidate variables influencing mood switching during TMS treatment and to develop effective preventative measures, especially for patients already predisposed to manic switching.Disclosure of InterestNone Declared

Use of nonlinear pulsed magnetic fields for spatial encoding in magnetic resonance imaging

This study examines the use of nonlinear magnetic field coils for spatial encoding in magnetic resonance imaging. Existing theories on imaging with such coils share a complex reconstruction process that originates from a suboptimal signal interpretation in the spatial-frequency domain (k-space). In this study, a new solution to this problem is proposed, namely a two-step reconstruction process, in which in the first step, the image signal is converted into a frequency spectrum, and in the second step, the spectrum, which represents the distorted image, is geometrically and intensity corrected to obtain an undistorted image. This theory has been verified by numerical simulations and experimentally using a straight wire as a coil model for an extremely nonlinear magnetic field. The results of this study facilitate the use of simple encoding coil designs that can feature low inductance, allowing for much faster switching times and higher magnetic field gradients.

New developments in cosmetic applications of electromagnetic fields: Client and occupational hazard assessment.

Energy-based devices are used to improve features of appearance for aesthetic reasons while avoiding more invasive methods. Examples of treatment targets are the reduction of wrinkles, sagging, unwanted skin lesions, body hair and excess fatty tissue, and the enhancement of muscle tissue. One treatment modality is the use of electromagnetic fields (EMF, 0‒300 GHz). The present work aims to give an up-to-date survey of cosmetic applications of EMF for professional use with an assessment of client and worker exposure and possible adverse effects. A systematic search was conducted for peer-reviewed articles (2007-2022), patents, premarket notifications, manufacturer data, and adverse effects reports. Five categories of cosmetic EMF device with increasing frequency were identified: sinusoid low frequency magnetic fields for lipolysis; pulsed low frequency magnetic fields for skin rejuvenation; pulsed low frequency magnetic fields for muscle building; radiofrequency EMF for lipolysis or skin rejuvenation; microwaves for hair removal or hyperhidrosis. In the vicinity of the last four device categories, there is a potential for exceeding the occupational exposure limits in the European Union EMF Directive, which could lead to nerve or muscle stimulation, burns or overheating. There are also potential hazards for clients or workers wearing active or passive medical devices. The severity of reported adverse effects increases with EMF frequency.

Abstract 490: Significant anti-proliferative effects of targeted magnetoelectric nanoparticles as potential theragnostic tools

Abstract Although current electroporation therapies have been demonstrated to be effective not only in ablating tumor tissue, but also in eliciting an anti-tumor immune response, they are limited in their application due to the strong risk factors associated with the high voltages required. Current methods of interacting with the body’s electrical currents are limited to traditional electrodes, which cause damage to surrounding tissue upon insertion, and require high voltages to create responses at the cellular level. Recent efforts at non-invasive interaction with the body’s electric fields have led to the fabrication of magnetoelectric nanoparticles (MENPs), a novel technology which has the ability to convert harmless magnetic fields into strong local electric fields, all while maintaining a diameter of ~70nm. These particles have been demonstrated to trigger neuronal firing under magnetic stimulation both in vitro and in vivo, and have been able to release chemotherapeutic agents on command in vitro and in vivo. This demonstrates the ability for MENPs to wirelessly generate electric fields within the body on demand with high temporal and spatial resolution. This suggests the potential for non-invasive electroporation therapy which could be triggered by external magnetic fields. Given the particles are themselves magnetic, this could show potential as a theragnostic tool as their magnetic properties suggest they may act simultaneously as an MRI contrast and an ablative therapy. To explore this possibility, we fabricated MENPs consisting of a magnetostrictive CoFe2O4 spinel core coupled with a piezoelectric BaTiO3 perovskite shell. These particles were then PEGylated to reduce agglomeration which is typical of magnetic nanoparticles. 50ul of a 1mg/ml PEG-MENP dispersion was deposited into a cell culture of SKOV-3 ovarian cancer cells. These cells were then stimulated by 120 10ms pulses of a 2kOe magnetic field over the course of 30 minutes. An cell-titre glo ATP assay was performed to indicate viability 24 hours after treatment. Treatment wells were compared to controls of no intervention, magnetic stimulation with no particles, and particles with no stimulation. The combination of particles and magnetic stimulation was the only group which showed significant decreases in viability, with a 32% reduction in viability. Particles on their own showed no effect on cell viability, neither did magnetic-only stimulation. This preliminary investigation into the use of MENPs as a non-invasive cancer treatment has shown some potential. The ability to wirelessly activate the particles provides an inherent targeting mechanism not found in traditional chemotherapeutics, while the nanometer diameter provides a non-invasive method to generate strong electric fields within the body. Citation Format: Max Shotbolt, Elric Zhang, Emily Zhu, Wael El-Rifai, John Bryant, Ping Liang, Sakhrat Khizroev. Significant anti-proliferative effects of targeted magnetoelectric nanoparticles as potential theragnostic tools [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 490.

60 T pulsed magnetic field in Bitter magnet made of tungsten and coiled by liquid helium

60 T pulsed magnetic field in Bitter magnet made of tungsten and coiled by liquid helium

Magnetic field control device for transplantation of corneal endothelial tissue with magnetic filaments.

The corneal endothelial transplantation involves the transfer and attachment of a single-layered corneal endothelial tissue to the narrow space between the cornea and iris. Given the high risk of damage to the endothelial tissue and surrounding corneal tissues when using sharp instruments inserted externally to apply force during the process, the development of a device capable of transferring corneal endothelial tissue using a magnetic field became necessary. This study aims to develop a magnetic control device for transferring corneal endothelial tissue with attached magnetic particles to the transplant site, validate its appropriate transfer capabilities, and assess its applicability to corneal endothelial transplantation. For this purpose, a magnetic field-generating manipulation device equipped with four electromagnets controlled by a joystick and microcomputer was developed. Through simulated experiments, the strength of the magnetic field and the attraction force on the tissue were predicted, and the actual magnetic field strength was measured for validation. To measure the magnetic transfer force, experiments were conducted by towing corneal endothelial tissue fixed with 6mg, 12mg, and 18mg plastic weights. Subsequently, the tissue's transfer speed was measured after applying continuous and pulsed magnetic fields. The results confirmed the feasibility of tissue transfer using the magnetic control device, and it was observed that pulsed magnetic fields led to faster transfer speeds and easier control compared to continuous magnetic fields. Exploratory animal experiments using rabbits were conducted to simulate real surgical conditions, confirming the feasibility of corneal endothelial tissue transfer and attachment.