In recent years, China's manned space program has advanced rapidly, with deep space exploration missions such as manned lunar landing steadily progressing, leading to a significant extension of astronauts' duration in outer space. In this context, the impact of the space magnetic field environment on astronaut health has become increasingly conspicuous. Characterized by its complexity, the spatial magnetic field indirectly regulates the circadian rhythm system by interfering with mitochondrial functions, such as electron transport chain activity, ATP synthesis efficiency, and reactive oxygen species (ROS) balance. This disruption can lead to circadian misalignment, sleep disorders, metabolic dysregulation, and other issues, severely compromising astronauts' physical and mental well-being, as well as mission performance. Currently, researchers have carried out extensive investigations into the influence of the space magnetic environment on circadian rhythms. Nevertheless, due to disparities in magnetic field parameters, exposure durations, and the model organisms employed in experiments, the results have been inconsistent. This review systematically elaborates on ground-based simulation technologies for spatial magnetic field environments and their applications, summarizes the effects of magnetic fields with varying intensities and types on core circadian rhythm biomarkers in model organisms and humans, and explores the underlying molecular and physiological mechanisms of magnetic field-induced circadian rhythm perturbation. This work aims to deepen the understanding of the mechanisms of the space magnetic environment on biological rhythms, and establish a scientific basis for formulating adaptive protective strategies centered on circadian regulation for astronauts, thereby ensuring the successful implementation of long-term deep-space missions.
Circadian Rhythm/physiology* ; Humans ; Magnetic Fields/adverse effects* ; Space Flight ; Animals ; Extraterrestrial Environment

The gradient field, one of the core magnetic fields in magnetic resonance imaging (MRI) systems, is generated by gradient coils and plays a critical role in spatial encoding and the generation of echo signals. The uniformity or linearity of the gradient field directly impacts the quality and distortion level of MRI images. However, traditional point measurement methods lack accuracy in assessing the linearity of gradient fields, making it difficult to provide effective parameters for image distortion correction. This paper introduced a spherical measurement-based method that involved measuring the magnetic field distribution on a sphere, followed by detailed magnetic field calculations and linearity analysis. This study, applied to assess the nonlinearity of asymmetric head gradient coils, demonstrated more comprehensive and precise results compared to point measurement methods. This advancement not only strengthens the scientific basis for the design of gradient coils but also provides more reliable parameters and methods for the accurate correction of MRI image distortions.
Magnetic Resonance Imaging/instrumentation* ; Humans ; Image Processing, Computer-Assisted/methods* ; Nonlinear Dynamics ; Magnetic Fields ; Algorithms ; Phantoms, Imaging

Alzheimer's disease (AD) is the most common degenerative disease of the nervous system. Studies have found that the 40 Hz pulsed magnetic field has the effect of improving cognitive ability in AD, but the mechanism of action is not clear. In this study, APP/PS1 double transgenic AD model mice were used as the research object, the water maze was used to group dementia, and 40 Hz/10 mT pulsed magnetic field stimulation was applied to AD model mice with different degrees of dementia. The behavioral indicators, mitochondrial samples of hippocampal CA1 region and electrocardiogram signals were collected from each group, and the effects of 40 Hz pulsed magnetic field on mouse behavior, mitochondrial kinetic indexes and heart rate variability (HRV) parameters were analyzed. The results showed that compared with the AD group, the loss of mitochondrial crest structure was alleviated and the mitochondrial dynamics related indexes were significantly improved in the AD + stimulated group ( P < 0.001), sympathetic nerve excitation and parasympathetic nerve inhibition were improved, and the spatial cognitive memory ability of mice was significantly improved ( P < 0.05). The preliminary results of this study show that 40 Hz pulsed magnetic field stimulation can improve the mitochondrial structure and mitochondrial kinetic homeostasis imbalance of AD mice, and significantly improve the autonomic neuromodulation ability and spatial cognition ability of AD mice, which lays a foundation for further exploring the mechanism of ultra-low frequency magnetic field in delaying the course of AD disease and realizing personalized neurofeedback therapy for AD.
Animals ; Heart Rate/physiology* ; Mice ; Alzheimer Disease/therapy* ; Mice, Transgenic ; Mitochondrial Dynamics/radiation effects* ; Magnetic Field Therapy/methods* ; Magnetic Fields ; Disease Models, Animal ; Mitochondria ; Male ; Maze Learning ; Cognition ; Dementia/therapy*

Tumor treating fields (TTF) therapy is an innovative tumor treatment modality. Currently, the TTF devices predominantly employ insulated ceramic electrodes as the electric field transmission medium, resulting in low energy transfer efficiency of the electric field and poor portability of the devices. This study proposed an innovative TTF transmission mode and independently designed a conducted-electrode TTF cell culture dish utilizing inert titanium materials. The electric field conduction characteristics were verified through finite element simulations and experimental tests. Finally, based on the self-manufactured conducted-electrode TTF cell culture dish, experiments on the proliferation inhibition of U87 tumor cells by TTF were conducted. The results demonstrated that under an applied TTF voltage of 10 V and frequency of 200 kHz, the electric field intensities within the medium for conducted and insulated electrodes are approximately 2.5 V/cm and 0.7 V/cm, respectively. Compared to conventional insulated TTF systems, the conducted-electrode TTF configuration exhibited a lower electrode voltage drop and a higher electric field intensity in the culture medium, indicating superior electric field transmission efficiency. Following 36 hours of treatment with conducted-electrode TTF on U87 cells, the proliferation inhibition rate reached approximately 50%, demonstrating effective suppression of tumor cell growth. This approach presents a potential direction for optimizing TTF treatment modality and device design.
Humans ; Electrodes ; Neoplasms/pathology* ; Cell Line, Tumor ; Cell Proliferation/radiation effects* ; Electric Stimulation Therapy/methods* ; Electromagnetic Fields

This study aims to investigate the therapeutic efficacy of 50 Hz-0.6 mT low-frequency pulsed electromagnetic field (PEMF) on postmenopausal osteoporosis in ovariectomized rats. Thirty 3-month-old female SD rats were selected and divided into a sham operation group (Sham), an ovariectomized model group (OVX), and a low-frequency pulsed electromagnetic field (PEMF) treatment group, with 10 rats in each group. After 8 weeks, the whole-body bone mineral density (BMD) of each group of rats was measured. The treatment group began to receive PEMF stimulation for 90 minutes daily, while the OVX group only received a simulated placement without electricity. After 6 weeks of intervention, all rats were sacrificed and tested for in vitro BMD, micro-CT, biomechanics, serum biochemical indicators, and bone tissue-related proteins. The results showed that the BMD of the OVX group was significantly lower than that of the Sham group 8 weeks after surgery, indicating successful modeling. After 6 weeks of treatment, compared with the OVX group, the PEMF group exhibited significantly increased BMD in the whole body, femur, and vertebral bodies. Micro-CT analysis results showed improved bone microstructure, significantly increased maximum load and bending strength of the femur, elevated levels of serum bone formation markers, and increased expression of osteogenic-related proteins. In conclusion, this study demonstrates that daily 90-minute exposure to 50 Hz-0.6 mT PEMF effectively enhances BMD, improves bone biomechanical properties, optimizes bone microstructure, stimulates bone formation, and inhibits bone resorption in ovariectomized rats, highlighting its therapeutic potential for postmenopausal osteoporosis.
Female ; Animals ; Rats, Sprague-Dawley ; Osteoporosis, Postmenopausal/therapy* ; Rats ; Bone Density ; Ovariectomy ; Magnetic Field Therapy/methods* ; Electromagnetic Fields

The gradient coils of MRI equipment can induce vibrations in implantable medical devices, causing periodic vibrations of implantable medical devices with respect to the surrounding tissue. This not only results in instrument failure but also causes discomfort to the patient. Therefore, studying the vibration characteristics of implantable devices under different scanning sequences and the orientation of the device relative to the magnetic field is crucial for comprehending vibration performance. This study observed the vibration spectra of a full cranial bone-implanted neurostimulator by using laser vibrometry under typical rapid imaging sequences and explored the impact of different magnetic field orientations on vibration. The results demonstrated that the rapid echo sequences induced diverse and rich vibration components, whereas the planar echo sequences caused relatively simple vibrations. Additionally, the strongest vibrations normally occurred in the maximum conductive surface parallel to the phase-coded direction. It revealed the factors influencing the vibrations of skull fixation active implantable devices and provided guidance for enhancing device safety and protecting patient well-being during MR examinations.
Vibration ; Magnetic Resonance Imaging ; Deep Brain Stimulation/instrumentation* ; Magnetic Fields ; Humans

In the YY 0989.3-2023 standard, clause 27.106 specifies the protection test against electromagnetic interference, but it only briefly describes the test level for electromagnetic exposure, and does not detail the parameters of the torso. This study aims to explore the internal field distribution for different torso parameters under electromagnetic exposure, and explore the patterns of field distribution through modeling and simulation. The results indicate that the parameters of the torso significantly affect the internal field distribution. The findings of this study provide a basis and reference for the electromagnetic compatibility test for implantable neurostimulator products.
Electromagnetic Fields ; Implantable Neurostimulators ; Computer Simulation

After the production of the gradient coil of the magnetic resonance imaging system, electromagnetic field testing is required to verify whether the assembly accuracy meets the electromagnetic field requirements. Since the passive magnetic field B _z satisfies the Laplace ^,s equation and is a harmonic function, and according to the extreme value principle of harmonic function, the maximum or minimum values of B _z can only appear on the boundaries, so the observation points of the magnetic field are generally selected on the surface of the spherical imaging area. For superconducting magnets used for human body magnetic resonance imaging, a spherical area with a center diameter of 40~50 cm is generally selected as the shimming target area. Only the field value of the target area needs to be measured, and the spherical harmonic coefficients obtained after data processing are used to determine the magnetic field performance of the gradient coil. There are many testing principles and methods for electromagnetic fields, so there is no unified way and method in the field of commercial applications. This article is based on the Gauss-Legendre numerical integration, measures and analyzes the magnetic field performance of gradient coils by building a data acquisition system, and this article applies numerical analysis methods to calculate the spherical harmonic coefficients of the magnetic field using discrete test data, providing a feasible method for the production and testing of gradient coils.
Magnetic Resonance Imaging/methods* ; Magnetic Fields ; Electromagnetic Fields ; Equipment Design

OBJECTIVES: To synthesize a temperature-responsive multimodal motion microrobot (MMMR) using temperature and magnetic field-assisted microfluidic droplet technology to achieve targeted drug delivery and controlled drug release. METHODS: Microfluidic droplet technology was utilized to synthesize the MMMR by mixing gelatin with magnetic microparticles. The microrobot possessed a magnetic anisotropy structure to allow its navigation and targeted drug release by controlling the temperature field and magnetic field. In the experiment, the MMMR was controlled to move in a wide range along a preset path by rotating a uniform magnetic field, and the local circular motion was driven by a planar rotating gradient magnetic field of different frequencies. The MMMR was loaded with simulated drugs, which were released in response to laser heating. RESULTS: Driven by a rotating magnetic field, the MMMR achieved linear motion following a predefined path. The planar gradient rotating magnetic field controlled circular motion of the MMMR with an adjustable radius, utilizing the centrifugal force generated by rotation. The drug-loaded MMMR successfully reached the target location under magnetic guidance, where the gelatin matrix was melted using laser heating for accurate drug release, after which the remaining magnetic particles were removed using magnetic field. CONCLUSIONS The MMMR possesses multimodal motion capabilities to enable precise navigation along a predefined path and dynamic regulation of drug release within the target area, thus having great potential for a wide range of biomedical applications.
Drug Delivery Systems/methods* ; Temperature ; Drug Liberation ; Magnetic Fields ; Robotics ; Gelatin/chemistry* ; Delayed-Action Preparations ; Microfluidics ; Motion

BACKGROUND: Numerous researches indicated that electromagnetic pulses (EMP) possessed advantages such as strong targeting, minimal side-effects and low treatment cost in tumor therapy, but its optimum parameters for treatment and the relationship between EMP and tumor-derived exosomes remains unclear. This study aims to clarify the effects of EMP with different parameters on the quantity and miRNA (microRNA) of exosomes secreted by human non-small cell lung cancer A549 cells, providing beneficial reference for the clinical application of EMP and related research. METHODS: A549 cells were randomly divided into control group and different EMP radiation groups with respective intensity of 400, 600 and 800 kV/m. EMP was performed with 2000 pulses once, 20 Hz of repetition frequency and 120 ns of pulse width. A549 cells were radiated once per day for continuous 3 days. After radiation, exosomes were collected and identified; cell number was measured by trypan blue staining; the concentration of exosomes was measured by nanoparticle tracking analysis (NTA); the abundance of miRNAs was determined by miRNA sequencing. RESULTS: Compared with control group, the morphology and cell viability of A549 cells in radiation group was not different, but the quantity of exosomes in 400 or 800 kV/m radiation group was significantly decreased (P<0.05), in contrast with obvious increase in 600 kV/m radiation group (P<0.05). The abundance of exosomal miRNAs between control group and each EMP group was obviously different (P<0.05) and target genes of differentially abundant miRNAs enriched in different pathways. CONCLUSIONS Under the experimental condition, the quantity and miRNA abundance of exosomes could be changed by EMP radiation, which could further influence the function of tumor-derived exosomes.
Humans ; Exosomes/genetics* ; A549 Cells ; MicroRNAs/metabolism* ; Lung Neoplasms/pathology* ; Cell Survival/radiation effects* ; Electromagnetic Fields