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Magnetic fields are widely used in medical diagnostics because of their superior non-invasive properties. In addition, with the widespread use of magnetic fields in transportation and other areas, their potential hazards to human health and the assessment of their safety have attracted considerable attention. The effects of magnetic fields on living organisms have a long history. The biological effects of magnetic field exposure in mice and rats depend on the magnetic field strength, exposure time, and direction; depending on these and potentially other factors, magnetic fields can cause a series of neurobiological effects. We reviewed global research on the neurobiological effects of magnetic fields from recent years to provide an overview and insights into the underlying mechanisms. This review focuses on the biological effects of static and dynamic magnetic fields of different frequencies and intensities on animals and nerve cells and their mechanisms of action. [ABSTRACT FROM AUTHOR]

Emerging miniaturized atomic sensors such as optically pumped magnetometers (OPMs) have attracted widespread interest due to their application in high-spatial-resolution biomagnetism imaging. While optical probing systems in conventional OPMs require bulk optical devices including linear polarizers and lenses for polarization conversion and wavefront shaping, which are challenging for chip-scale integration. In this study, an integrated optical probing scheme based on localized-interference metasurface for chip-scale OPM is developed. Our monolithic metasurface allows tailorable linear polarization conversion and wavefront manipulation. Two silicon-based metasurfaces namely meta-polarizer and meta-polarizer-lens are fabricated and characterized, with maximum transmission efficiency and extinction ratio (ER) of 86.29 % and 14.2 dB for the meta-polarizer as well as focusing efficiency and ER of 72.79 % and 6.4 dB for the meta-polarizer-lens, respectively. A miniaturized vapor cell with 4 × 4 × 4 mm3 dimension containing 87Rb and N2 is combined with the meta-polarizer to construct a compact zero-field resonance OPM for proof of concept. The sensitivity of this sensor reaches approximately 9 fT/Hz1/2 with a dynamic range near zero magnetic field of about ±2.3 nT. This study provides a promising solution for chip-scale optical probing, which holds potential for the development of chip-integrated OPMs as well as other advanced atomic devices where the integration of optical probing system is expected. [ABSTRACT FROM AUTHOR]

Purpose: 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. Methods: 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. Results: 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). Conclusion: 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. [ABSTRACT FROM AUTHOR]

Background: Inflammation is caused by an excess of Sodium ions inside the cell. This generates a variation in the cell's membrane electric potential, becoming a steady state from a thermodynamic viewpoint. Methods: This paper introduces a thermodynamic approach to inflammation based on the fundamental role of the electric potential of the cell membrane, introducing an analysis of the effect of heat transfer related to the inflammation condition. Results: The direct proportionality between the reduction in temperature and the increase of Na+ outflow may ameliorate the inflammation cascade. Conclusions: Based on these ion fluxes, we suggest the consideration of a 'companion' electromagnetic therapeutic wave concept in support of the present anti-inflammatory treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Magnetic nanomaterials have biological activities such as promoting osteogenic differentiation of stem cells and inhibiting osteoclast formation, and can effectively promote the healing of injured bone tissue under the synergistic effect of magnetic fields. They have a very broad application prospect in bone injury repair. OBJECTIVE: To review the mechanism of magnetic nanomaterials and magnetic fields promoting bone repair, as well as their research progress in the field of bone injury repair. METHODS: Relevant literature search was conducted in PubMed and Web of Science databases with the search terms "magnetic nanomaterials, magnetic field, bone repair, bone tissue engineering, stem cell, osteoblast, osteoclast." The time limit of literature search was from 2003 to 2023, which was screened and analyzed. Some classic articles were manually retrieved, and 98 articles were finally included for RESULTS AND CONCLUSION: (1) Magnetic nanomaterials have biological effects such as promoting osteoblast differentiation, inhibiting osteoclast formation and regulating the immune microenvironment. In addition, magnetic nanomaterials can regulate the physicochemical properties of tissue engineering scaffolds, such as mechanical properties and surface morphology, and endowed with magnetic properties, which is conducive to the regulation of the adhesion, proliferation and osteogenic differentiation of stem cells. (2) The magnetic field has the ability to regulate multiple cell signaling pathways to promote osteoblast differentiation, inhibit osteoclast formation, stimulate angiogenesis and other biological effects, thus accelerating the healing of damaged bone tissue. (3) The joint application of magnetic nanomaterials and magnetic field accelerates the repair of bone damage by activating mechanotransduction, increasing the content of intracellular magnetic nanoparticles, and enhancing the effect of micro-magnetic field, which provides a new idea for the research of bone tissue engineering. (4) Magnetic field has demonstrated definite efficacy in the treatment of clinical fractures, osteoporosis, and osteoarthritis diseases, which is beneficial for bone tissue growth, reducing bone loss, alleviating pain, and improving the quality of life of patients. (5) Magnetic nanomaterials and magnetic fields have great potential for application in bone damage repair and regeneration, but the interaction mechanism between magnetic nanomaterials, magnetic fields, and cells has not been fully elucidated. Moreover, the key parameters of magnetic fields that regulate intracellular molecular events, including the type, intensity, frequency, duration, and mode of the magnetic field, as well as the precise biological effects of a specific magnetic field on osteoblasts and the underlying mechanisms, have yet to be defined. (6) Further attention needs to be paid to the effects on osteoclasts, nerves, blood vessels, and immune cells in the microenvironment of damaged tissues. Finally, the safety of magnetic materials for human use is yet to be systematically studied in terms of their distribution, metabolism, and acute and chronic toxicities. [ABSTRACT FROM AUTHOR]

Abstract While magnetomyography (MMG) using optically pumped magnetometers (OPMs) is a promising method for non-invasive investigation of the neuromuscular system, it has almost exclusively been performed in magnetically shielded rooms (MSRs) to date. MSRs provide extraordinary conditions for biomagnetic measurements but limit the widespread adoption of measurement methods due to high costs and extensive infrastructure. In this work, we address this issue by exploring the feasibility of mobile OPM-MMG in a setup of commercially available components. From field mapping and simulations, we find that the employed zero-field OPM can operate within a large region of the mobile shield, beyond which residual magnetic fields and perturbations become increasingly intolerable. Moreover, with digital filtering and moderate averaging a signal quality comparable to that in a heavily shielded MSR is attained. These findings facilitate practical and cost-effective implementations of OPM-MMG systems in clinical practice and research.

Magnetoencephalography (MEG) systems are advanced neuroimaging tools used to measure the magnetic fields produced by neuronal activity in the human brain. However, they require significant amounts of liquid helium to keep the superconducting quantum interference device (SQUID) sensors in a stable superconducting state. Additionally, MEG systems must be installed in a magnetically shielded room to minimize interference from external magnetic fields. We have developed an advanced MEG system that incorporates a superconducting magnetic shield and a zero-boil-off system. This system overcomes the typical limitations of traditional MEG systems, such as the frequent need for liquid helium refills and the spatial constraints imposed by magnetically shielded rooms. To validate the system, we conducted an evaluation using signal source estimation. This involved a phantom with 50 current sources of known location and magnitude under active zero-boil-off conditions. Our evaluations focused on the precision of the magnetic field distribution and the quantification of estimation errors. We achieved a consistent magnetic field distribution that matched the source current, maintaining an estimation error margin within 3.5 mm, regardless of the frequency of the signal source current. These findings affirm the practicality and efficacy of the system. [ABSTRACT FROM AUTHOR]

Monitoring atmospheric pollution in urban areas is challenging because pollutant deposition occurs at short distances, requiring a large amount of sampling and analysis to characterize it. Ecological indicators can help overcome this problem, allowing us to select sites with the highest deposition of pollutants from the atmosphere. Nevertheless, a major gap is the temporal characterization of the accumulation rate of magnetic particles in ecological indicators, which is critical to understand if the bioaccumulation process is linear or if saturation occurs. To overcome this problem, Parmotrema perlatum lichens were magnetically and chemically studied in a pollution gradient over space and time. Lichen transplants were exposed over 18 weeks to a high-traffic road. Results show that magnetic properties and element composition reflected both distance from the road (nonlinear decrease of up to 100 m from source) and exposure time (increasingly linearly over the entire study period with eightfold increments), showing that up to 18 weeks, the accumulation rate remained constant over time, with no saturation occurring. Chemical analysis showed a strong linear relationship between the accumulation of zinc (Zn), antimony (Sb), manganese (Mn), copper (Cu) chromium (Cr) and magnetic susceptibility. Magnetization acquisition curves reveal a time-dependent low-coercivity component, interpreted as mainly related to nonexhaust, mostly brake abrasion particle emissions. It is concluded that the magnetic properties of lichen transplants can be used in urban environments to characterize the spatial and temporal patterns of the deposition of pollution metallic particles from the atmosphere. [ABSTRACT FROM AUTHOR]

The emergence of biomagnetism imaging has led to the development of ultrasensitive and compact spin-exchange relaxation-free (SERF) atomic magnetometers that promise high-resolution magnetocardiography (MCG) and magnetoencephalography (MEG). However, conventional optical components are not compatible with nanofabrication processes that enable the integration of atomic magnetometers on chips, especially for elliptically polarized laser-pumped SERF magnetometers with bulky optical systems. In this study, an elliptical-polarization pumping beam (at 795 nm) is achieved through a single-piece metasurface, which results in an SERF magnetometer with a high sensitivity reaching 10.61 fT/Hz1/2 by utilizing a 87Rb vapor cell with a 3 mm inner diameter. To achieve the optimum theoretical polarization, our design combines a computer-assisted optimization algorithm with an emerging metasurface design process. The metasurface is fabricated with 550 nm thick silicon-rich silicon nitride on a 2 × 2 cm2 SiO2 substrate and features a 22.17° ellipticity angle (a deviation from the target polarization of less than 2%) and more than 80% transmittance. This study provides a feasible approach for on-chip polarization control of future all-integrated atomic magnetometers, which will further pave the way for high-resolution biomagnetism imaging and portable atomic sensing applications. [ABSTRACT FROM AUTHOR]

Active topological phase transitions widely occur in active matters and biological systems, such as developing embryos. Since the discovery of the intriguing bulk-boundary effects of topological insulators in Hermitian and non-Hermitian systems, various electric, optical, acoustic, and mechanical topological metamaterials with efficient energy transmission and robust defect-immunization have been designed. To date, however, it remains a challenge to precisely and fast manipulate the topological phase transitions in elastic topological insulators. In this paper, on the basis of theoretical analysis and numerical simulations, we propose an active strategy to achieve this aim through a combination of pneumatic actuation and liquid metals. The proposed method can precisely tune the connecting stiffness and vertex mass in the tight Su–Schrieffer–Heeger model. Thus, we realize the effective and fast control of topological phase transitions and elastic wave bandgap switching. We also uncover the active spinning bulk-boundary effects and higher-order topological states in the elastic topological insulators, demonstrating the high effectiveness and practicability of the proposed method. In addition, the differences between the 1D edge and 0D corner higher-order states are specified by information entropy theory. This work not only gains insights into the active manipulation of topological phase transitions but also inspires novel strategies to design active topological materials through untethered methods, e.g., magnetism or biological cells. [ABSTRACT FROM AUTHOR]

We are engaged in the development and clinical application of a neural magnetic field measurement system that utilizes biomagnetic measurements to observe the activity of the spinal cord and peripheral nerves. Unlike conventional surface potential measurements, biomagnetic measurements are not affected by the conductivity distribution within the body, making them less influenced by the anatomical structure of body tissues. Consequently, functional testing using biomagnetic measurements can achieve higher spatial resolution compared to surface potential measurements. The neural magnetic field measurement, referred to as magnetoneurography, takes advantage of these benefits to enable functional testing of the spinal cord and peripheral nerves, while maintaining high spatial resolution and noninvasiveness. Our magnetoneurograph system is based on superconducting quantum interference devices (SQUIDs) similar to the conventional biomagnetic measurement systems. Various design considerations have been incorporated into the SQUID sensor array structure and signal processing software to make it suitable for detecting neural signal propagation along spinal cord and peripheral nerve. The technical validation of this system began in 1999 with a 3-channel SQUID system. Over the course of more than 20 years, we have continued technological development through medical-engineering collaboration, and in the latest prototype released in 2020, neural function imaging of the spinal cord and peripheral nerves, which could also be applied for the diagnosis of neurological disorders, has become possible. This paper provides an overview of the technical aspects of the magnetoneurograph system, covering the measurement hardware and software perspectives for providing diagnostic information, and its applications. Additionally, we discuss the integration with a helium recondensing system, which is a key factor in reducing running costs and achieving practicality in hospitals. [ABSTRACT FROM AUTHOR]

Single‐beam atomic magnetometers herald a new era of high‐precision magnetic field sensing, with applications spanning fundamental physics to biomagnetism. Nevertheless, their utility is often curtailed by quantum sensor noise, encompassing both technical and quantum‐mechanical noise. This research delves into the potential of the Kalman filter as a tool to subdue quantum sensor noise, thereby augmenting the sensitivity of single‐beam atomic magnetometers. Quantum‐mechanical noise is integrated into the system model as the process noise and measurement noise, and a discrete Kalman filter equipped with a time delay variable is employed. The findings reveal that the time delay variable significantly influences temporal signal tracing, while the discrete Kalman filter enhances sensitivity performance in frequency domain analysis, bypassing the typical sensitivity and time resolution trade‐off encountered in coherent sensing strategies. Partial‐knowledge signal scenarios are also taken into account, wherein a polynomial model is proposed to expansively render the discrete Kalman filter more relevant and adaptable to real‐world situations. Collectively, through experimentation involving sine‐like, non‐Gaussian, and medical magnetocardiography (MCG) signals, our results underscore the promising potential of the Kalman filter in enhancing the sensitivity of atomic magnetometers for practical sensing applications. [ABSTRACT FROM AUTHOR]

The article discusses the field of magnetobiology, which studies the non-thermal effects of magnetic fields on biological systems. The literature in this field is often plagued by conflicting claims and methodological shortcomings, leading to an unbalanced body of research. The article highlights the potential of the radical pair mechanism (RPM) in understanding the effects of magnetic interactions in living systems. It specifically focuses on the RPM's role in the magnetic compass sense of migratory songbirds and its potential applications in other areas of magnetobiology. The article also mentions the importance of realistic models and experimental optimization in studying radical pair reactions. [Extracted from the article]

Background: Inflammation is caused by an excess of Sodium ions inside the cell. This generates a variation in the cell’s membrane electric potential, becoming a steady state from a thermodynamic viewpoint. Methods: This paper introduces a thermodynamic approach to inflammation based on the fundamental role of the electric potential of the cell membrane, introducing an analysis of the effect of heat transfer related to the inflammation condition. Results: The direct proportionality between the reduction in temperature and the increase of Na+ outflow may ameliorate the inflammation cascade. Conclusions: Based on these ion fluxes, we suggest the consideration of a ‘companion’ electromagnetic therapeutic wave concept in support of the present anti-inflammatory treatment.

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Obesity is now considered a public health problem. It is treated as a chronic disease where the accumulation of body fat occurs due to several factors, such as complex morphological changes resulting from the interaction of lifestyle, genetic and emotional factors. Therefore, the need for therapies that help to improve the quality of life of people with this disease becomes quite viable. This study was carried out with the objective of describing the Medicinal Biomagnetism (MB) therapy helping obese individuals to lose weight. There are numerous scientific research aimed at studying the causes of the development of obesity. There is a variety of “recipes”, medicines, therapies, formulas, proteins, diets, etc., in order to treat obesity. These techniques are usually offered at a high cost, and are almost always not performed correctly, so they do not have the desired effects. In this research, we present a possibility of low-cost, non-invasive therapy, called Medicinal Biomagnetism that uses medium intensity magnets with the objective of providing not only quality of life, but also assisting in weight loss. In this research, the 3D movement protocol 1, 3D movement protocol 2 and specific special pairs were used. The result achieved so far gives us hope that it is possible to lose weight without the use of any medication and with a low investment cost, considering the health gain obtained by the patient. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue in the International Journal of Molecular Sciences that showcases the current state of biophysics research in the Russian Federation. The issue includes articles that present the findings from the VII Congress of Russian Biophysicists, which covered a wide range of topics such as molecular biophysics, cell biophysics, membrane processes, bioenergy, biophotonics, and medical biophysics. The congress highlighted the physical mechanisms at work in biological processes and emphasized the influence of physicochemical factors on living systems. The document concludes by mentioning the upcoming congress in 2027. [Extracted from the article]

Magnetoencephalography (MEG) systems are advanced neuroimaging tools used to measure the magnetic fields produced by neuronal activity in the human brain. However, they require significant amounts of liquid helium to keep the superconducting quantum interference device (SQUID) sensors in a stable superconducting state. Additionally, MEG systems must be installed in a magnetically shielded room to minimize interference from external magnetic fields. We have developed an advanced MEG system that incorporates a superconducting magnetic shield and a zero-boil-off system. This system overcomes the typical limitations of traditional MEG systems, such as the frequent need for liquid helium refills and the spatial constraints imposed by magnetically shielded rooms. To validate the system, we conducted an evaluation using signal source estimation. This involved a phantom with 50 current sources of known location and magnitude under active zero-boil-off conditions. Our evaluations focused on the precision of the magnetic field distribution and the quantification of estimation errors. We achieved a consistent magnetic field distribution that matched the source current, maintaining an estimation error margin within 3.5 mm, regardless of the frequency of the signal source current. These findings affirm the practicality and efficacy of the system.

Monitoring atmospheric pollution in urban areas is challenging because pollutant deposition occurs at short distances, requiring a large amount of sampling and analysis to characterize it. Ecological indicators can help overcome this problem, allowing us to select sites with the highest deposition of pollutants from the atmosphere. Nevertheless, a major gap is the temporal characterization of the accumulation rate of magnetic particles in ecological indicators, which is critical to understand if the bioaccumulation process is linear or if saturation occurs. To overcome this problem, Parmotrema perlatum lichens were magnetically and chemically studied in a pollution gradient over space and time. Lichen transplants were exposed over 18 weeks to a high-traffic road. Results show that magnetic properties and element composition reflected both distance from the road (nonlinear decrease of up to 100 m from source) and exposure time (increasingly linearly over the entire study period with eightfold increments), showing that up to 18 weeks, the accumulation rate remained constant over time, with no saturation occurring. Chemical analysis showed a strong linear relationship between the accumulation of zinc (Zn), antimony (Sb), manganese (Mn), copper (Cu) chromium (Cr) and magnetic susceptibility. Magnetization acquisition curves reveal a time-dependent low-coercivity component, interpreted as mainly related to nonexhaust, mostly brake abrasion particle emissions. It is concluded that the magnetic properties of lichen transplants can be used in urban environments to characterize the spatial and temporal patterns of the deposition of pollution metallic particles from the atmosphere.

In this paper we present a novel noninvasive approach to estimate current densities in the heart from magnetocardiography. The proposed algorithm uses nested optimization to model current densities in equally-sized voxels of myocardial tissue. First-order Thiran all-pass filters are used to describe the propagation between voxels.We demonstrate feasibility of the algorithm for a noise-free single-layer simulation. However, challenges remain, such as addressing measurement noise and optimizing propagation velocity. Overall, this approach has the potential to complement or replace invasive catheter-based electrophysiological studies for localization of arrhythmogenic tissue.

An uracil-azo derivative of quinoline, 1,3-dimethyl-5-(8′-quinolinyl-azo)-6-aminouracil (H2L, 1), was synthesized and then converted into its atropisomers, 1,3-dimethyl-8-(8′-quinolinyl)azaxanthine (α-atropisomer (2) and β-atropisomer (3)). It is indeed a notable accomplishment that the atropisomers were synthesized selectively under dissimilar reaction conditions. Additionally, an axially elongated 5-coordinated distorted square pyramidal copper(II)-complex, [CuII(HL)(H2O)2]NO3 (4), was synthesized from H2L, where it acts as a tridentate ligand. Single crystals of compounds 2–4 were analyzed for their stereochemical characterization. The compounds (2 and 3) belong to the same space group P21 with Z = 2. Based on a torsional angle about N3–N2–C1–C9, which is 48.7(2)° for the α-atropisomer (2) and −48.7(2)° for the β-atropisomer (3), respectively, they are revealed to be atropisomers. According to TD-DFT analysis, the α-atropisomer (2) is 0.05 kcal mol−1 more energetically stable than the β-atropisomer (3). The 5-coordinated Cu1 centre adopts a distorted square pyramidal geometry (space group P21/n, Z = 4), wherein the coordination sites were occupied by three-N and two O-donor atoms from the HL− moiety and the two H2O molecules, respectively. The polycrystalline sample of 4 was subjected to direct current (dc) variable-temperature magnetic susceptibility studies over the temperature range of 1.8–300 K. The magnetic study suggests that copper(II) ions in the crystal lattice have a weak antiferromagnetic interaction, demonstrating the complex to be a mononuclear species. According to the EPR study, the distorted square-pyramidal copper(II) complex may have a dx2−y2 orbital as a ground state. All the compounds have shown significant efficacy against the bacterial plant pathogen, Ralstonia solanacearum Smith. and the fungal plant pathogen, Rhizoctonia solani Kuhn., which cause bacterial wilting of solanaceous crops and sheath blight of rice, respectively. Besides, the atropisomers have demonstrated effectiveness against another bacterial plant pathogen, Xanthomonas oryzaepv. oryzae. that causes bacterial blight of rice. The atropisomers thus differ with respect to biological efficacy towards both bacterial and fungal diseases. [ABSTRACT FROM AUTHOR]

Simple Summary: The study of the biological effects of time-varying magnetic fields has attracted more and more attention from researchers, and the number of publications on this topic is growing every year. In this article, we plan to briefly introduce the reader to the results of research, ideas, and discussions on the biological effects of time-varying magnetic fields. This article is illustrated with a large number of generalizing figures and contains a lot of factual data. This review presents the main biological effects observed during magnetic storms and in laboratory studies. The general concepts of studying the influence of magnetic storms on humans are described. Possible approaches to modeling magnetobiological effects at different levels of the organization of living things are presented. The results of the impact of anthropogenic fields on humans (epidemiological studies) are presented. The mechanisms of action of time-varying magnetic fields on living objects are discussed. Dependences of quantitative characteristics of the biological action of time-varying magnetic fields on their frequency, induction, and duration are discussed. The information presented in this manuscript may be valuable for a wide range of readers in the initial assessment of the risks associated with the influence of time-varying magnetic fields on the body. Magnetic fields are a constant and essential part of our environment. The main components of ambient magnetic fields are the constant part of the geomagnetic field, its fluctuations caused by magnetic storms, and man-made magnetic fields. These fields refer to extremely-low-frequency (<1 kHz) magnetic fields (ELF-MFs). Since the 1980s, a huge amount of data has been accumulated on the biological effects of magnetic fields, in particular ELF-MFs. However, a unified picture of the patterns of action of magnetic fields has not been formed. Even though a unified mechanism has not yet been generally accepted, several theories have been proposed. In this review, we attempted to take a new approach to analyzing the quantitative data on the effects of ELF-MFs to identify new potential areas for research. This review provides general descriptions of the main effects of magnetic storms and anthropogenic fields on living organisms (molecular–cellular level and whole organism) and a brief description of the main mechanisms of magnetic field effects on living organisms. This review may be of interest to specialists in the fields of biology, physics, medicine, and other interdisciplinary areas. [ABSTRACT FROM AUTHOR]

Electroanatomical mapping is a method for creating a model of the electrophysiology of the human heart. Medical professionals routinely locate and ablate the site of origin of cardiac arrhythmias with invasive catheterization. Non-invasive localization takes the form of electrocardiographic (ECG) or magnetocardiographic (MCG) imaging, where the goal is to reconstruct the electrical activity of the human heart. Non-invasive alternatives to catheter electroanatomical mapping would reduce patients' risks and open new venues for treatment planning and prevention. This work introduces a new system state-based method for estimating the electrical activity of the human heart from MCG measurements. Our model enables arbitrary propagation paths and velocities. A Kalman filter optimally estimates the current densities under the given measurements and model parameters. In an outer optimization loop, these model parameters are then optimized via gradient descent. This paper aims to establish the foundation for future research by providing a detailed mathematical explanation of the algorithm. We demonstrate the feasibility of our method through a simplified one-layer simulation. Our results show that the algorithm can learn the propagation paths from the magnetic measurements. A threshold-based segmentation into healthy and pathological tissue yields a DICE score of 0.84, a recall of 0.77, and a precision of 0.93. [ABSTRACT FROM AUTHOR]

This article presents a review of domestic research on the development of new medical equipment and technologies using equipment and methods of detection of natural magnetic fields of biological objects. The core of the biomagnetic research technology consists of noncontact detection, special mathematical processing, and analysis of the values of the parameters of the magnetic field of the investigated bioobject (generated by the heart, brain, muscles, etc.) found in the specified points of space outside the body of the bioobject using highly sensitive magnetometer equipment, and in particular, using superconducting quantum interference devices (SQUIDs). Based on the studies of myocardial electrophysiology, the samples of technical solutions of magnetometric SQUID-systems for magnetocardiography (MCG), data on diagnostic capabilities, and prospects of practical application of MCG in cardiology are presented. The methodology of magnetocardiographic examination is described and the advantages of MCG application for early diagnosis and control of therapy of various cardiovascular diseases (CVDs) are described. The work of the software of MAG-SCAN diagnostic complexes for the analysis of magnetocardiosignals is illustrated by solving the problem of classifying groups of cardiological patients. [ABSTRACT FROM AUTHOR]

A generalized spectral analytical method is outlined—a new approach to processing information arrays. The theoretical foundations of the method are presented, as well as its applications to various problems of processing of experimental data and problems of analysis, recognition, and diagnostics of biomedical and bioinformation systems. Examples of its use for studying biomagnetic data and structures of biomacromolecules are given. The problems of its application for image analysis and recognition are formulated. The method is based on the adaptive decomposition of the original arrays in a functional basis from among classical algebraic systems of polynomials and functions (Jacobi, Chebyshev, Lagrange, Laguerre, and Gegenbauer polynomials, etc., having one and two variables), as well as spherical functions. This approach combines analytical and digital data-processing procedures and is in fact a universal combined technology for processing information arrays. [ABSTRACT FROM AUTHOR]

The present study used a simplified axisymmetric biomagnetic fluid dynamics and porous media model which includes FHD (Ferrohydrodynamics), porosity and inertia effects saturated by magnetic dipole to study the influences of the leading parameters on various flow variables along a flat plate. The governing equations are simplified and solved by finite difference approach. We clarify how the ferromagnetic interaction parameter B and porosity e assumptions contribute in the bio-background of the problem of interest. Moreover, from the results of the flow profiles, accelerating and decelerating phenomena are noticed for B and e interaction. [ABSTRACT FROM AUTHOR]

In this paper we present a novel noninvasive approach to estimate current densities in the heart from magnetocardiography. The proposed algorithm uses nested optimization to model current densities in equally-sized voxels of myocardial tissue. First-order Thiran all-pass filters are used to describe the propagation between voxels.We demonstrate feasibility of the algorithm for a noise-free single-layer simulation. However, challenges remain, such as addressing measurement noise and optimizing propagation velocity. Overall, this approach has the potential to complement or replace invasive catheter-based electrophysiological studies for localization of arrhythmogenic tissue. [ABSTRACT FROM AUTHOR]

Accurate characterization of atomic vapor cells is crucial for enhancing the sensitivity of miniature atomic magnetometers. In this study, a fast and efficient approach is developed to characterize relaxation properties of the inner surface of the 87Rb micro-electro-mechanical systems (MEMS) vapor cell. Based on the zero-field level crossing effect, the transverse relaxation rate was experimentally determined, and the depolarization coefficient of 0.097 for atom-wall collisions in the 87Rb MEMS vapor cell was obtained. The experiments demonstrated that the alkali-wall collision relaxation gradually dominates the depolarization of the 87Rb ensemble as the radius of the vapor cell decreases. This research provides a quantitative method to evaluate the effectiveness of the MEMS vapor cell anti-relaxation coatings and offers the design inspiration for MEMS atomic vapor cells from the perspective of relaxation characterization. It is beneficial for the development of weak magnetic field detections such as biomagnetism detection in ambient environments. [ABSTRACT FROM AUTHOR]

Using spin‐exchange relaxation‐free (SERF) atomic magnetometer array (AMA) in magnetocardiography and magnetoencephalography has presented a challenge in reducing its packing volume for integrated instrumentation and convenient maintenance. This study presents a novel, space‐saving SERF AMA based on an 8‐channel planar lightwave circuit (PLC) waveguide splitter with a compact footprint of 26 × 2.5 mm2. The PLC splitting configuration allows the synchronization of the pump for a multisensor array, resulting in highly consistent performance among the sensors, with an impressive ultrahigh sensitivity of 34 fT Hz−1/2 within a measurement bandwidth of 105 Hz. The PLC splitting method shows great promise in expanding the channel capacity of small‐scale SERF AMAs, offering a cost‐effective method for high‐resolution medical diagnoses through functional magnetic imaging of humans. In addition, this method is expected to find applications in fields such as electromagnetic induction imaging, biological magnetism, and geomagnetic observation. [ABSTRACT FROM AUTHOR]

Dramatically increased levels of electromagnetic radiation in the environment have raised concerns over the potential health hazards of electromagnetic fields. Various biological effects of magnetic fields have been proposed. Despite decades of intensive research, the molecular mechanisms procuring cellular responses remain largely unknown. The current literature is conflicting with regards to evidence that magnetic fields affect functionality directly at the cellular level. Therefore, a search for potential direct cellular effects of magnetic fields represents a cornerstone that may propose an explanation for potential health hazards associated with magnetic fields. It has been proposed that autofluorescence of HeLa cells is magnetic field sensitive, relying on single-cell imaging kinetic measurements. Here, we investigate the magnetic field sensitivity of an endogenous autofluorescence in HeLa cells. Under the experimental conditions used, magnetic field sensitivity of an endogenous autofluorescence was not observed in HeLa cells. We present a number of arguments indicating why this is the case in the analysis of magnetic field effects based on the imaging of cellular autofluorescence decay. Our work indicates that new methods are required to elucidate the effects of magnetic fields at the cellular level. [ABSTRACT FROM AUTHOR]

Some animals are known to be able to react to very small changes in the magnetic field (a thousand times smaller than the geomagnetic field) and to use this ability to navigate the Earth's magnetic landscape. However, the nature of the molecular sensor of the magnetic field remains uncertain, though it has been established that the magnetic sense is associated with vision. A magnetochemical reaction is believed to underlie the functioning of the magnetic sensor. The cryptochromes of photoreceptors lining the retina contain photoinduced spin-correlated pairs of radicals which are involved in forming nerve impulses and are sensitive to magnetic fields. On this basis, animals may sense the magnetic field as changes in brightness over large visual fields, and orient themselves in terms of the contrast of these fields. However, the sensitivity of individual sensors – radical pairs – is very low. It has previously been supposed that this difficulty is overcome by a statistical increase in contrast sensitivity due to the parallel processing by the brain of the primary signals of millions of photoreceptors. We report here testing of this hypothesis. The threshold sensation of brightness contrast was found to depend almost linearly on the logarithm of the angular size of the contrasting stimulus, which is typical for the physiology of sensations obeying the Weber–Fechner law. Contrast sensitivity increases with increases in the number of photoreceptors involved in stimulus recognition, though this increase is quantitatively insufficient to provide a confident explanation of magnetic navigation in animals. [ABSTRACT FROM AUTHOR]

In this paper, we study the laminar, incompressible, and steady flow of a biomagnetic fluid, such as blood, containing gold nanoparticles through a shrinking sheet in the presence of a magnetic dipole. This model is consistent with both the principles of magnetohydrodynamics (MHD) and ferro-hydrodynamics (FHD). An effective numerical method that is based on an iterative process, tridiagonal matrix manipulation, and a common finite difference method with central differencing is used to generate the numerical solution of obtained ordinary differential equations (ODEs). The major numerical results show that the fluid velocity decreases as the ferromagnetic number increases whereas the skin friction coefficient shows the opposite behavior. As the ferromagnetic number increases, the rate of heat transfer with ferromagnetic interaction parameter is likewise observed and shown to be decreasing. [ABSTRACT FROM AUTHOR]

In this paper, the effects of various fluid properties on two-dimensional unsteady biomagnetic fluid flow (blood) and heat transfer over a stretching sheet under the appearance of a magnetic dipole is investigated. The governing boundary layer equations are simplified via suitable transformation which are then solved using the bvp4c function approach in MATLAB software. The results indicate that fluid velocity and temperature are greatly influenced by the ferromagnetic interaction parameter. With increasing ferromagnetic number, fluid velocity drops but temperature increases. It is also found that the coefficient of skin friction and Nusselt number increase with an increase in values of thermal conductivity parameter. For certain parameter values, the results are also compared with previously published studies and they are found to be in acceptable agreement. [ABSTRACT FROM AUTHOR]

Biomagnetism is the measurement of the weak magnetic fields produced by nerves and muscle. The magnetic field of the heart—the magnetocardiogram (MCG)—is the largest biomagnetic signal generated by the body and was the first measured. Magnetic fields have been detected from isolated tissue, such as a peripheral nerve or cardiac muscle, and these studies have provided insights into the fundamental properties of biomagnetism. The magnetic field of the brain—the magnetoencephalogram (MEG)—has generated much interest and has potential clinical applications to epilepsy, migraine, and psychiatric disorders. The biomagnetic inverse problem, calculating the electrical sources inside the brain from magnetic field recordings made outside the head, is difficult, but several techniques have been introduced to solve it. Traditionally, biomagnetic fields are recorded using superconducting quantum interference device (SQUID) magnetometers, but recently, new sensors have been developed that allow magnetic measurements without the cryogenic technology required for SQUIDs. [ABSTRACT FROM AUTHOR]

The continuously changing magnetic field of the Earth and its constant influence on the vital activity of all living organisms makes studies of magnetobiological effects important and in demand. The effects of weak magnetic fields, especially weak static magnetic fields, on living objects remains inappropriately understudied. The biological effects of weak magnetic fields result from chemical processes involving radicals, radical ions, and paramagnetic particles. As attenuation of the magnetic field is a stress factor for the body and given that the nervous system performs the most important regulatory functions in forming the body's stress response, this review addresses the influences of weak static magnetic fields on the functioning of the nervous system. Our own and published data are summarized; these indicate that weak static magnetic fields affect key biological processes, such as gene expression, cell proliferation and differentiation, and apoptosis, as well as behavior. Special attention is paid to the therapeutic potential of weak magnetic fields for clinical use in neurological pathologies. [ABSTRACT FROM AUTHOR]

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The mechanistic Monte Carlo modeling of biological effects of ionising radiation at sub-cellular and DNA scale requires the accurate simulation of track structures in the biological medium, commonly approximated as liquid water. The formalism of microdosimetry allows one to describe quantitatively the spatial distribution of energy deposition in the irradiated medium, which is known to relate to the deleterious effects in the irradiated cellular targets. The Geant4-DNA extension of the Geant4 open-source and general-purpose Monte Carlo simulation toolkit has been recently evaluated for the simulation of microdosimetry spectra, allowing, in particular, the calculation of lineal energy distributions. In this work, we extend the microdosimetric functionalities of Geant4-DNA by the development of a new Geant4-DNA example dedicated to the simulation of differential proximity functions. Simulation results are presented for the proximity function of electrons, protons, and alpha particles over a wide energy range using the different physical models of electron interactions available in Geant4-DNA. The influence of sub-excitation processes and electron tracking cut is discussed. Results are compared to literature data when available. As an example, a simple calculation of the relative biological effectiveness (RBE) in the context of the Theory of Dual Radiation Action using the present proximity functions yields up to a factor of 2 variation of the electron RBE in the energy range from 100 eV to 100 keV. [ABSTRACT FROM AUTHOR]

Three-axis atomic magnetometers have great advantages for interpreting information conveyed by magnetic fields. Here, we demonstrate a compact construction of a three-axis vector atomic magnetometer. The magnetometer is operated with a single laser beam and with a specially designed triangular 87 Rb vapor cell (side length is 5 mm). The ability of three-axis measurement is realized by reflecting the light beam in the cell chamber under high pressure, so that the atoms before and after reflection are polarized along two different directions. It achieves a sensitivity of 40 f T / H z in x-axis, 20 f T / H z in y-axis, and 30 f T / H z in z-axis under spin-exchange relaxation-free regime. The crosstalk effect between different axes is proven to be little in this configuration. The sensor configuration here is expected to form further values, especially for vector biomagnetism measurement, clinical diagnosis, and field source reconstruction. [ABSTRACT FROM AUTHOR]

As one of the common variable magnetic fields, rotating magnetic field (RMF) plays a crucial role in modern human society. The biological effects of RMF have been studied for over half a century, and various results have been discovered. Several reports have shown that RMF can inhibit the growth of various types of cancer cells in vitro and in vivo and improve clinical symptoms of patients with advanced cancer. It can also affect endogenous opioid systems and rhythm in central nerve systems, promote nerve regeneration and regulate neural electrophysiological activity in the human brain. In addition, RMF can influence the growth and metabolic activity of some microorganisms, alter the properties of fermentation products, inhibit the growth of some harmful bacteria and increase the susceptibility of antibiotic-resistant bacteria to common antibiotics. Besides, there are other biological effects of RMF on blood, bone, prenatal exposure, enzyme activity, immune function, aging, parasite, endocrine, wound healing, and plants. These discoveries demonstrate that RMF have great application potential in health care, medical treatment, fermentation engineering, and even agriculture. However, in some cases like pregnancy, RMF exposure may need to be avoided. Finally, the specific mechanisms of RMF's biological effects remain unrevealed, despite various hypotheses and theories. It does not prevent us from using it for our good. [ABSTRACT FROM AUTHOR]

We assume that the enzymatic processes of recognition of amino acids and their addition to the synthesized molecule in cellular translation include the formation of intermediate pairs of radicals with spin-correlated electrons. The mathematical model presented describes the changes in the probability of incorrectly synthesized molecules in response to a change in the external weak magnetic field. A relatively high chance of errors has been shown to arise from the statistical enhancement of the low probability of local incorporation errors. This statistical mechanism does not require a long thermal relaxation time of electron spins of about 1 μ s—a conjecture often used to match theoretical models of magnetoreception with experiments. The statistical mechanism allows for experimental verification by testing the usual Radical Pair Mechanism properties. In addition, this mechanism localizes the site where magnetic effects originate, the ribosome, which makes it possible to verify it by biochemical methods. This mechanism predicts a random nature of the nonspecific effects caused by weak and hypomagnetic fields and agrees with the diversity of biological responses to a weak magnetic field. [ABSTRACT FROM AUTHOR]

Background: Persons with cosmetic tattoos occasionally experience severe pain and burning sensation on magnetic resonance imaging (MRI). Objective: To explore the culprit magnetic substances in commonly used permanent makeup inks. Material and methods: 20 inks used for cosmetic tattooing of eyebrows, eyeliners, and lips were selected. Ink bottles were tested for magnetic behavior with a neodymium magnet. Eight iron oxide inks qualified for the final study. Metals were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP‐MS). The magnetic fraction of inks was isolated and analyzed by X‐ray fluorescence (XRF). Magnetic iron compounds were characterized by Mössbauer spectroscopy and powder X‐ray diffraction (XRD). Results: ICP‐MS showed iron in all magnetic samples, and some nickel and chromium. Mössbauer spectroscopy and XRD detected ferromagnetic minerals, particularly magnetite, followed by goethite and hematite. Conclusion: This original study of cosmetic ink stock products made with iron oxide pigments reports magnetic impurities in inks for cosmetic tattooing, e.g., magnetite, goethite, and hematite. These may be the main cause of MRI burn sensation in cosmetic tattoos. The mechanism behind sensations is hypothesized to be induction of electrical stimuli of axons from periaxonal pigment/impurity activated by magnetic force. Magnetite is considered the lead culprit. [ABSTRACT FROM AUTHOR]

Magnetic resonance provides exquisite anatomical images and functional MRI monitors physiological activity by recording blood oxygenation. This review attempts to answer the following question: Can MRI be used as a sensor to directly record neural behavior? It considers MRI sensing of electrical activity in the heart and in peripheral nerves before turning to the central topic: recording of brain activity. The primary hypothesis is that bioelectric current produced by a nerve or muscle creates a magnetic field that influences the magnetic resonance signal, although other mechanisms for detection are also considered. Recent studies have provided evidence that using MRI to sense neural activity is possible under ideal conditions. Whether it can be used routinely to provide functional information about brain processes in people remains an open question. The review concludes with a survey of artificial intelligence techniques that have been applied to functional MRI and may be appropriate for MRI sensing of neural activity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mesenchymal stem cells, with self-replication and multidirectional differentiation potential, attracted much attention in the field of bone tissue regeneration. As a non-invasive physical stimulation factor, the magnetic field can effectively regulate the biological behaviors of mesenchymal stem cells such as adhesion, proliferation, osteogenic differentiation and mineralization, which means that it has a broad application prospect in bone tissue regeneration medicine. The effect of the magnetic field depends on parameters such as magnetic field strength, frequency and exposure time. Due to the window effect, the appropriate parameter range of magnetic field promoting bone regeneration remains to be clarified. OBJECTIVE: To review the effects of different magnetic fields and different magnetic parameters on osteogenic differentiation of mesenchymal stem cells as well as the possible mechanisms, and to summarize the appropriate parameters for promoting proliferation and osteogenic differentiation. METHODS: Databases of CNKI and PubMed were searched for relevant articles published from January 2010 to September 2021 using the keywords including “magnetic field, static magnetic field, pulsed electromagnetic field, mesenchymal stem cells, proliferation, osteogenic differentiation, bone regeneration, bone repair” in Chinese and English. A few classic early articles were also included. By reading the titles and abstracts, a preliminary screening was conducted. Repetitive studies, low-quality or irrelevant articles were excluded. Finally, a total of 56 articles were retained and analyzed for this review. RESULTS AND CONCLUSION: (1) Moderate static magnetic field, low frequency or low intensity pulsed electromagnetic field, have positive effects on the proliferation and osteogenic differentiation of mesenchymal stem cells. High-frequency pulsed electromagnetic field produces obvious inhibitory effect. (2) The magnetic field modulation effect was positively correlated with the total exposure time, but its effect did not increase with the time of single intermittent exposure. (3) Factors outside the magnetic field, such as stem cell type, differentiation stage, and cell density, also have complex effects on the biological effects of the magnetic field, which should be paid attention to in clinic. (4) Magnetic fields have effects on cellular targets such as plasma membrane, cytoskeleton and ion channel. The possible mechanisms mainly include magnetomechanical interaction, electrodynamic interaction and free radical effect. [ABSTRACT FROM AUTHOR]

With the widespread use of static magnetic fields (SMFs) in medicine, it is imperative to explore the biological effects of SMFs and the mechanisms underlying their effects on biological systems. The presence of magnetic materials within cells and organisms could affect various biological metabolism and processes, including stress responses, proliferation, and structural alignment. SMFs were generally found to be safe at the organ and organism levels. However. human subjects exposed to strong SMFs have reported side effects. In this review, we combined the magnetic properties of biological samples to illustrate the mechanism of action of SMFs on biological systems from a biophysical point of view. We suggest that the mechanisms of action of SMFs on biological systems mainly include the induction of electric fields and currents, generation of magnetic effects, and influence of electron spins. An electrolyte flowing in a static magnetic field generates an induced current and an electric field. Magnetomechanical effects include orientation effects upon subjecting biological samples to SMFs and movement of biological samples in strong field gradients. SMFs are thought to affect biochemical reaction rates and yields by influencing electron spin. This paper helps people how can harness the favorable biological effects of SMFs. [ABSTRACT FROM AUTHOR]

Magntoenterogram (MENG) is a functional imaging method with great clinical potential for non-invasive diagnosis of intestinal diseases. In measurements of MENG, the cardiac artifacts are a strong biological source of interference. Based on wire-wound SQUID gradiometers, we constructed a planar mounted full-tensor compensation module for MENG system, which can obtain cardiac artifacts while suppressing ambient noise, so as to denoise MENG signals without increasing external ECG recording channels. The cardiac artifacts are regressed out from the full-tensor compensation module outputs, which can denoise the MENG measurements. Using this module, the SNR is about 70 dB better than the raw data. At last, 36-point array MENG signals were detected successfully and the contour map of jejunal slow-wave frequency (SWF) was consistent with the jejunal area (one part of the small intestine). This method will save costs and avoid the new electromagnetic interferences introduced by ECG equipment. It will lay a good foundation for the rapid clinical application of the MENG system. [ABSTRACT FROM AUTHOR]

Electroanatomical mapping is a method for creating a model of the electrophysiology of the human heart. Medical professionals routinely locate and ablate the site of origin of cardiac arrhythmias with invasive catheterization. Non-invasive localization takes the form of electrocardiographic (ECG) or magnetocardiographic (MCG) imaging, where the goal is to reconstruct the electrical activity of the human heart. Non-invasive alternatives to catheter electroanatomical mapping would reduce patients’ risks and open new venues for treatment planning and prevention. This work introduces a new system state-based method for estimating the electrical activity of the human heart from MCG measurements. Our model enables arbitrary propagation paths and velocities. A Kalman filter optimally estimates the current densities under the given measurements and model parameters. In an outer optimization loop, these model parameters are then optimized via gradient descent. This paper aims to establish the foundation for future research by providing a detailed mathematical explanation of the algorithm. We demonstrate the feasibility of our method through a simplified one-layer simulation. Our results show that the algorithm can learn the propagation paths from the magnetic measurements. A threshold-based segmentation into healthy and pathological tissue yields a DICE score of 0.84, a recall of 0.77, and a precision of 0.93.