Low Frequency Magnetic Fields Research Articles

Effect of black highland barley polysaccharides and low frequency-static magnetic field on casein-based coacervates: Formation, characterization, and probiotic encapsulation capacity.

To evaluate the combination effects of highland barley polysaccharides (HBP) and low-frequency static magnetic field (LF-SMF) treatment on the structure and properties of acid-induced casein (CS) coacervates, this study conducted a comprehensive investigation at various stages- before, during, and after coacervation-for the first time. Compared with native CS, adding HBP caused CS to denature owing to hydrophobic and electrostatic interactions, and LF-SMF treatment further promoted these changes. During the acidification (pH7.0-2.0) and coacervation processes, the integration of LF-SMF treatment with the addition of HBP enhanced the rate and extent of casein (CS) aggregation and crosslinking, attributable to alterations in the ζ-potential of CS. Among the formed coacervates, the yield and particle size of CS/HBP complex coacervates after being treated with LF-SMF (M-CS/HBP) increased from 67.9% to 78.4% and from 803.12nm to 1253.43nm, respectively. Additionally, M-CS/HBP demonstrated improved viscoelasticity and a more uniform, compact microstructure with denser packing. The alterations observed in CS-based coacervates were due to non-covalent interactions between CS and HBP, further promoted by LF-SMF treatment, leading to the unfolding and disordering of protein secondary structure. Consequently, M-CS/HBP complex coacervates demonstrated superior encapsulation efficiency for L. plantarum and provided enhanced protection for probiotics under adverse environments.

Magnetic field normalization in residential premises located above built-in transformer substations 6(10)/0,4 kV power 100-400 kVA

The purpose of the work is to define methods and means of screening, sufficient to reduce to a safe level the low frequency magnetic field in residential premises of old buildings, located above built-in transformer substations 6(10)/0,4 kV power 100–400 kVA at short distances to the premises. To achieve this goal, a modified method for synthesizing active shielding systems of the magnetic field for transformer substations at short distances from the substation to the floor of the premises, and its experimental verification was carried out on a full-scale physical model of a transformer substation power 100 kVA with a physical layout of the synthesized active shielding system. A synthesis of active shielding systems of magnetic field for transformer substations with a power of 100–400 kVA at short distances from the substation to the floor of the premises and an analysis of their effectiveness were carried out. It was determined that the normalization of the magnetic field on the floor surface for transformer substations with a power of 100 kVA using a synthesized active shielding system with one compensation winding is possible at distances of at least 1,15 m from the substation, and with two windings - at least 1,02 m. It was determined that normalization of the magnetic field on the floor surface for 400 kVA transformer substations using a synthesized active shielding system with two windings is possible only at a distance from the substation of at least 1,6 m. An analysis of the effectiveness of the combined use of active and passive shielding was conducted. It was determined that the combined use of synthesized two-channel active shielding systems and a passive flat electromagnetic shield made of 4 mm thick aluminum sheet allows reducing the magnetic field above the built-in transformer substation with a power of 100 to 400 kVA to the normative level while limiting the distance from the substation to the floor of the premises to at least 1,08 m and provides protection of public health from the effects of the low frequency magnetic field.

A High-Precision Real-Time Temperature Acquisition Method Based on Magnetic Nanoparticles.

The unique magnetothermal properties of magnetic nanoparticles enable the development of a high-precision, real-time, noninvasive temperature measurement method with significant potential in the biomedical field. Based on a low-frequency alternating magnetic field excitation model, we construct two additional magnetic field excitation models-alternating current-direct current superposition and dual-frequency superposition-to extract harmonic amplitude components from the magnetization response. To increase the accuracy of harmonic information acquisition, the effects of the truncation error, excitation magnetic field frequency, and amplitude are thoroughly analyzed, and optimal parameter values are selected to minimize the error. A single algorithm is designed for temperature inversion, and a joint algorithm is proposed to optimize the performance of the single algorithm. Under low-frequency alternating-current magnetic field excitation, the autonomous group particle swarm optimization method achieves superior real-time performance in terms of temperature inversion and running time. Compared with the opposition learning gray wolf optimizer and particle swarm optimization-gray wolf optimization, the proposed method achieves reductions of 52% and 68%, respectively. Additionally, under dual-frequency superimposed magnetic field excitation, a higher temperature inversion accuracy is achieved compared with that of the particle swarm optimization-gray wolf optimization algorithm, reducing the error from 0.237 K to 0.094 K.

Magnetic fields from indoor transformer stations and risk of cancer in adults: a cohort study

ObjectivesStudies assessing the association of adult cancers with extremely low frequency (ELF) magnetic fields (MF) have provided inconclusive results, probably affected by limitations such as low exposure levels, confounding and...

Extremely low frequency magnetic fields (ELF-MF) in Switzerland: From exposure monitoring to daily exposure scenarios

Exposure to extremely low frequency magnetic fields (ELF-MF) is ubiquitous in our daily environment. This study aims to provide a comprehensive overview of the ambient ELF-MF exposure in Switzerland and presents a novel environmental exposure matrix for exposure assessment and risk communication. Magnetic flux density levels (µT) were measured using a portable exposimeter carried in a backpack for the main ELF sources: railway power (16.7 Hz), domestic power (50 Hz), and tram ripple current (300 Hz). We collected ELF-MF levels between 2022 and 2024 in various environments representative of the Swiss population: 300 outdoor areas (e.g. city centres, residential areas), 245 public spaces (e.g. train stations, schools), 348 transport journeys (e.g. train, cars), and in 59 homes (e.g. bedrooms, living rooms). Over all environments, the highest ELF-MF exposure levels were measured in train stations (median: 0.48 µT), trains (median: 0.40 µT), and in living rooms near (<200 m) highest voltage lines of 220 kV and 380 kV (median: 0.37 µT). ELF-MF median levels measured two years apart showed high Pearson correlation coefficients in the same 150 outdoor areas (r = 0.88) and 86 public spaces (r = 0.87), without any significant changes. All measurements are well below the Swiss ambient regulatory limit based on the ICNIRP 1998 guidelines (median: 0.2 %). Finally, we derived an environmental exposure matrix and modelled 27 daily time-weighted average ELF-MF exposure scenarios by combining typical time spent at home, work and transport environments. People who do not live near highest voltage lines or work in highly exposed environments are typically exposed to less than 0.3 µT on average, while those who do are likely to exceed this level. This novel environmental exposure matrix is a useful tool for public communication and agent-based exposure modelling for future epidemiological research.

A Novel E-E-Type Electrically Modulated Magnetoelectric Sensor for Extremely Low-Frequency Magnetic Field Detection

A Novel E-E-Type Electrically Modulated Magnetoelectric Sensor for Extremely Low-Frequency Magnetic Field Detection

Evaluation of Low Frequency Electrical and Magnetic Fields in a Electrical Transmission Substation

Evaluation of Low Frequency Electrical and Magnetic Fields in a Electrical Transmission Substation

The Effect of Low-Frequency Magnetic Fields with Low Induction and Red LED Light on Keratinocyte Biological Activity-An In Vitro Research Model.

For several decades, there has been growing interest in the influence of low-frequency magnetic fields (LFMFs) and red LED light on the healing process. Keratinocytes are cells that play a significant role in the process of wound healing and tissue regeneration. A human keratinocyte cell line (HaCaT) was exposed to an LFMF with low induction (180-195 Hz; 60 µT, magnetostimulation), red LED light (630 nm; 300 mW, LED therapy), and their combined action (magneto-LED therapy) in in vitro culture conditions. On day 4 and 8 of the experiment, the following parameters were determined: adhesion/proliferation, adenylate kinase (AK), nitric oxide (NO), cytokines (IL-1β, IL-6, IL-8, IL-10, IL-12p70, TNF-α), metalloproteinases (MMP-2, MMP-9), and collagen IV. It was shown that magnetostimulation caused an increase in keratinocyte adhesion/proliferation and IL-8 secretion and a decrease in IL-12 secretion. The LED therapy resulted in a transient increase in the secretion of NO and cytokines IL-1, IL-12, and IL-6 in keratinocytes. The use of magneto-LED therapy resulted in an increase in keratinocyte adhesion/proliferation, the secretion of cytokines IL-6 and IL-8, and NO with a simultaneous decrease in MMP-9 secretion. The results of our studies showed that the action of an LFMF with low-induction and LED light on keratinocytes can modulate the biological activity of keratinocytes towards improving the skin healing process.

A new tumor-treating device OM-100 with low-frequency magnetic fields inhibits proliferation and metastasis in liver cancer

BackgroundThis study aims to investigate a novel instrument OM-100 with low-frequency magnetic fields (LFMFs) for its potential applicability in the treatment of liver cancer.MethodsLiver cancer cell lines (HepG2 and Huh7) and normal liver cell line THLE-2 were exposed to OM-100 at LFMFs of 0, 10, 25, 50, and 100 kHz for 2 h in the morning, noon, and evening, respectively. The effects of LFMF on cell viability, apoptosis, migration, and invasion capabilities were examined. Additionally, impacts of LFMF on ROS production was assessed. In vivo studies were conducted to examine the safety profile of OM-100 and its effects on tumor growth.ResultsIn vitro, OM-100 reduced the viability of liver cancer cells, increased cell apoptosis, and inhibited cell migration and invasion abilities in a frequency-dependent manner (P < 0.05). In vivo, OM-100 significantly slowed down tumor growth and promoted apoptosis in liver tumors (P < 0.05). Moreover, OM-100 rarely affected the viability of normal liver cells, as well as the health of normal mice. Finally, we further found that OM-100 significantly increased the production of ROS in liver cancer cells (P < 0.05), a key factor in inducing autophagy, which is very important for the progression of liver cancer.ConclusionOur findings reveal the safety of OM-100 and its frequency at 100 kHz significantly inhibits liver cancer progression.

Rotary excitation of non-sinusoidal pulsed magnetic fields: Towards non-invasive direct detection of cardiac conduction.

There is a need for high resolution non-invasive imaging methods of physiologic magnetic fields. The purpose of this work is to develop a MRI detection approach for non-sinusoidal magnetic fields based on the rotary excitation (REX) mechanism which was previously successfully applied for the detection of oscillating magnetic fields in the sub-nT range. The new detection concept was examined by means of Bloch simulations, evaluating the interaction effect of spin-locked magnetization and low-frequency pulsed magnetic fields. The REX detection approach was validated under controlled conditions in phantom experiments at 3 T. Gaussian and sinc-shaped stimuli were investigated. In addition, the detection of artificial fields resembling a cardiac QRS complex, which is the most prominent peak visible on a magnetocardiogram, was tested. Bloch simulations demonstrated that the REX method has a high sensitivity to pulsed fields in the resonance case, which is met when the spin-lock frequency coincides with a non-zero Fourier component of the stimulus field. In the experiments, we found that magnetic stimuli of different durations and waveforms can be distinguished by their characteristic REX response spectrum. The detected REX amplitude was proportional to the stimulus peak amplitude (R2 > 0.98) and the lowest field detection was 1 nT. Furthermore, the detection of QRS-like fields with varying QRS durations yielded significant results in a phantom setup (p < 0.001). REX detection can be transferred to non-sinusoidal pulsed magnetic fields and could provide a non-invasive, quantitative tool for spatially resolved assessment of cardiac biomagnetism. Potential applications include the direct detection and characterization of cardiac conduction.

Effects of mercury and magnetic fields on the activity of proteinases and glycosidases in the intestine of common carp Cyprinus carpio.

Aquatic ecosystems are increasingly affected by anthropogenic pollution, including heavy metals like mercury, which accumulate in organisms and cause harmful effects. At the same time, human activities such as industrial operations and the use of electric power lines also alter the magnetic background in natural water bodies. However, the interaction between mercury exposure and magnetic fields remains poorly understood. This study aimed to investigate the combined effects of mercury and magnetic fields on the digestive enzyme activity of common carp (Cyprinus carpio), focusing on the relevance of magnetic fields due to their increasing presence in industrialized environments. Two groups of fish were fed diets with low (0.02mg/kg) or high (0.27mg/kg) mercury content for 6months and exposed to extremely low-frequency magnetic fields or hypomagnetic conditions. Results showed significant differences in mercury accumulation between groups, with higher levels in carps fed with high-mercury content diets. These fish also exhibited increased body length and weight compared to those on a low-mercury diet. The amylolytic activity (total activity of enzymes hydrolyzing starch: α-amylase, glucoamylase, and maltase) and proteolytic activity (total activity of serine proteinases) in the fish intestine were assessed. Magnetic exposure had contrasting effects on enzyme activity, depending on mercury levels in the diet. Fish fed the low-mercury diet exhibited decreased amylolytic activity following magnetic field exposure, while fish on the high-mercury diet showed increased activity. Proteolytic activity followed a similar pattern, with opposite effects observed between the two dietary groups. These findings suggest that mercury accumulation alters the biological response to magnetic fields, possibly through compensatory biochemical mechanisms. Understanding the interactions between toxic substances and magnetic fields is critical for improving environmental risk assessments.

Accelerating T1 relaxation time measurements of noble gas using transverse low-frequency square-wave magnetic field modulation.

The longitudinal relaxation time (T1) of noble gas nuclear spins is a critical parameter for evaluating the performance of an atomic comagnetometer, significantly influencing the signal-to-noise ratio of the system. Traditional measurement techniques, such as the free induction decay method combined with the spin growth technique (FIDSG), are time-consuming for gases with extended T1 durations, such as 21Ne, and are prone to substantial environmental variability. Here, we propose the transverse low-frequency square-wave magnetic field modulation (LSMM) method for the rapid measurement of T1. The experiment indicates that the LSMM significantly condenses the measurement time to 19.2% of the original, thereby diminishing the robustness demands of the system. Although a minor discrepancy of up to 3 min (or 1.3%) exists between LSMM and FIDSG results, the LSMM method provides strong support for calibrating the performance of comagnetometer cells and conducting various nuclear spin polarization experiments, thereby improving efficiency and reducing energy loss.

A low frequency magnetic field regulated the synthesis of carotenoids in Rhodotorula mucilaginosa by influencing iron metabolism

The purpose of this study is to investigate the effect of low frequency magnetic fields (LFMF) on carotenoid synthesis and iron metabolism in Rhodotorula mucilaginosa and to explore potential connections between the two processes. Various LFMF intensities were employed to assess carotenoid production, intracellular iron content, and the expression levels of genes related to carotenoid synthesis and iron metabolism in R. mucilaginosa. The results show that a LFMF could promote carotenoid synthesis, resulting in varying increases in intracellular iron content. Specifically, the expression of the iron metabolism-related gene transferrin receptor (TFR) was upregulated, while the expression of ferroportin 1 (FPN1) was downregulated. Meanwhile, the expressions of the carotenoid synthesis-related genes geranylgeranyl diphosphate synthases (GGPPS) and phytoene synthase (PSY) displayed varying degrees of upregulation at different time points. Further, the TFR and FPN1 gene knockout strains of R. mucilaginosa were subjected to treatment with a 3.5-mT LFMF, the results of which showed that an LFMF is capable of influencing the iron metabolism levels and subsequently regulating carotenoid synthesis in R. mucilaginosa.

Extremely low-frequency magnetic fields affect the movement of magnetotactic cocci

Extremely low-frequency magnetic fields affect the movement of magnetotactic cocci

3D Position Tracking Using On-Chip Magnetic Sensing in Image-Guided Navigation Bronchoscopy.

This paper presents a compact and low-cost on-chip sensor and readout circuit. The sensor achieves high-resolution 5-degrees-of-freedom (DoF) tracking (x, y, z, yaw, and pitch). With the help of an external wire wound sensor, it can also achieve high-resolution 6-degrees-of-freedom (DoF) tracking (x, y, z, yaw, pitch, and roll angles). The sensor uses low-frequency magnetic fields to detect the position and orientation of instruments, providing a viable alternative to using X-rays in image-guided surgery. To measure the local magnetic field, a highly miniaturised on-chip magnetic sensor capable of sensing the magnetic field has been developed incorporating an on-chip magnetic sensor coil, analog-front end, continuous-time ∆Σ analog-to-digital converter (ADC), LVDS transmitter, bandgap reference, and voltage regulator. The microchip is fabricated using 65 nm CMOS technology and occupies an area of 1.06 mm 2, the smallest reported among similar designs to the best of our knowledge. The 5-DoF system accurately navigates with a precision of 1.1 mm within the volume-of-interest (VOI) of 15 ×15 ×15 cm 3. The 6-DoF system achieves a navigation accuracy of 0.8 mm and an angular error of 1.1 degrees in the same VOI. These results were obtained at a 20 Hz update rate in benchtop characterisation. The prototype sensor demonstrates accurate position tracking in real-life pre-clinical in-vivo settings within the porcine lung of a live swine, achieving a reported worst-case registration accuracy of 5.8 mm.

Metformin represses the carcinogenesis potentially induced by 50 Hz magnetic fields in aged mouse fibroblasts via inhibition of NF-kB.

Aging is a risk factor for various human disorders, including cancer. Current literature advocates that the primary principles of aging depend on the endogenous stress-induced DNA damage caused by reactive oxygen species 50 Hz low-frequency magnetic field was suggested to induce DNA damage and chromosomal instability. NF-kB, activated by DNA damage, is upregulated in age-related cancers and inhibition of NF-kB results in aging-related delayed pathologies. Metformin (Met), an NF-kB inhibitor, significantly reduces both NF-kB activation and expression in aging and cancer. This invitro study, therefore, was set out to assess the effects of 5mT MF in 50 Hz frequency and Met treatment on the viability and proliferation of aged mouse NIH/3T3 fibroblasts and expression of RELA/p65, matrix metalloproteinases MMP2 and MMP9, and E-cadherin (CDH1) genes. The trypan blue exclusion assay was used to determine cell viability and the BrdU incorporation assay to determine cell proliferation. The MMP-2/9 protein analysis was carried out by immunocytochemistry, NF-kB activity by ELISA and the expressions of targeted genes by qRT-PCR methods. Four doses of Met (500 uM, 1 mM, 2 mM and 10 mM) suppressed both the proliferation and viability of fibroblasts exposed to the MF in a dose-dependent pattern, and the peak inhibition was recorded at the 10 mM dose. Met reduced the expression of NF-kB, and MMP2/9, elevated CDH1 expression and suppressed NF-kB activity. These findings suggest that Met treatment suppresses the carcinogenic potential of 50 Hz MFs in aged mouse fibroblasts, possibly through modulation of NF-kB activation and epithelial-mesenchymal transition modulation.

A non-resonant piezoelectric generator for extracting energy from low-frequency magnetic field

A non-resonant piezoelectric generator for extracting energy from low-frequency magnetic field

Karpman–Washimi ponderomotive force and self-generated magnetic field in nonextensive plasmas

The non-stationary Karpman–Washimi ponderomotive force and self-generated magnetic field in an unmagnetized system are investigated in the context of nonextensive distribution based on the kinetic theory. The ponderomotive force, magnetization, and radiation power are obtained as functions of the nonextensive parameter q, wave frequency, and wave number. It is shown that the presence of high-velocity electrons leads to an increase in temporal and spatial variation parts of ponderomotive force, magnetization, and radiation power. Furthermore, the results indicate that the self-generated magnetic field driven by the Karpman–Washimi ponderomotive force primarily manifests as small-scale and low-frequency magnetic field.

A one-step fabrication method of flexible magnetostrictive fiber ribbon based on Fe50Co50 alloy and its characteristics study

Magnetostrictive materials are widely used in sensors, actuators and micro-nano electronics because of their excellent performance. However, traditional rigid magnetostrictive materials are difficult to adapt to the flexible and deformable structure of flexible electronic devices. In order to solve the deformation, sensing and control problems in the field of flexible electronics, a one-step new method of is proposed to deposit Fe50Co50 fiber ribbons with reciprocated and loop structures on flexible substrate. Helmholtz coil is designed to test the magnetostrictive positive effect ability of Fe50Co50 ribbon, and its magnetostrictive strain curve is analyzed. Furthermore, frequency domain characteristics of Fe50Co50 ribbon are tested, and the influence of externally driving magnetic field on elastic layer materials and resonance output characteristics is analyzed. The experimental results show that Fe50Co50 ribbon exhibits good low-frequency magnetic field characteristics. And free end displacement of Fe50Co50 ribbon based on loop structure, under 12 mT alternating magnetic field and 134 mT bias magnetic field, reaches a peak-to-peak value of 870 μm for first-order resonance, and 320 μm for second-order resonance. This verifies that Fe50Co50 ribbon possesses the expected properties that magnetostrictive materials should have, and innovatively breaks through the technical bottleneck of manufacturing flexible micro-nano magnetostrictive energy exchange components.

Lower magnetic field measurement limit of the coupled dark state magnetometer

Abstract The Coupled Dark State Magnetometer (CDSM) is an optically pumped magnetometer. For the Jupiter Icy Moons Explorer (JUICE) mission, the CDSM and two fluxgate magnetometers are combined in the J-MAG instrument to measure the static and low frequency magnetic field in the Jupiter system. During certain calibration manoeuvres, the CDSM has to be able to measure magnetic field strengths down to 100 nT with an accuracy of 0.2 nT (1 σ). At such low magnetic fields, the CDSM’s operational parameters must be carefully selected to obtain narrow resonance structures. Otherwise, the coupled dark state resonances, used for the magnetic field detection in different instrument modes, overlap and result in a systematic error. In this paper we demonstrate that with the found instrument settings the CDSM is able to measure magnetic field strengths below 100 nT with a systematic error less than 0.2 nT resulting from the overlap of the resonances.