Search Results (569)

Magnetic fields (MFs) represent an emerging modality in cancer therapy, encompassing static, low-frequency, pulsed, and nanoparticle-mediated alternating fields. These interventions have demonstrated the capacity to modulate proliferation, apoptosis, ferroptosis, migration, and epithelial-to-mesenchymal transition (EMT) in tumor cells, often through reactive oxygen species (ROS) modulation, ion channel regulation, membrane receptor dynamics, and lysosomal membrane permeabilization. Magnetic nanoparticle hyperthermia (MHT) has reached clinical application, showing promising outcomes in glioblastoma and prostate cancer, while pulsed electromagnetic fields (PEMFs) and magneto-mechanical approaches are under preclinical investigation. The mechanistic diversity of MFs allows synergistic combination with chemotherapy, radiotherapy, and immunotherapy. However, parameter sensitivity, field standardization, and long-term safety remain challenges. Here, we review mechanistic insights, signaling pathways, and experimental and clinical evidence for MF-based cancer therapies, highlighting translational potential and the need for rigorous optimization to realize clinical efficacy. Full article

In this paper, we investigate the dynamics of quantum correlations in the ground-state hyperfine manifold of the hydrogen atom subjected to a static external magnetic field and local pure dephasing. The electron–proton spin pair is modeled as a bipartite two-qubit system evolving under the combined effects of hyperfine coupling, Zeeman splitting, and a Lindblad master equation that describes Markovian dissipative processes. Employing exact analytical solutions for the time-dependent density matrix elements (derived in the Markovian open-system framework), we quantify entanglement persistence via concurrence and state stability via Uhlmann fidelity with respect to the initial preparation. For an initial Werner state, numerical results reveal that the external magnetic field substantially modifies the system dynamics: Both concurrence and fidelity exhibit pronounced dependence on the Zeeman parameter, producing field-controlled oscillations, delayed entanglement sudden death, and altered decoherence rates. This behavior originates from Zeeman-induced lifting of hyperfine degeneracies, symmetry breaking of the isotropic Werner state, and redistribution of populations and coherences. Unlike previous studies that treat hyperfine interactions, Zeeman splitting, or decoherence in isolation, the present work provides a unified analytical treatment that simultaneously incorporates all three mechanisms. The findings underscore the competition between coherent hyperfine coupling and environmental noise and open new pathways for precision spectroscopy and robust quantum information protocols based on atomic spin degrees of freedom. Full article

Online monitoring of polyacrylamide (PAM) concentration is needed for quality control in continuous fracturing-fluid blending and for closed-loop smart fracturing operations. This study evaluates the feasibility and current limits of an MR-based PAM assay route. Static CPMG-T2 tests on an existing 4.6 MHz magnetic resonance multiphase flowmeter (MRMF) platform showed that T2-based viscosity discrimination is useful when the PAM concentration is above approximately 3‰, but it becomes insufficient in the 1–3‰ low-concentration interval. A 20 MHz laboratory T2-D validation test indicated that the apparent diffusion coefficient responds more clearly to PAM-induced molecular-mobility variation than T2 alone. On this basis, a 23.5 MHz diffusion-capable online detector concept was developed, featuring a permanent-magnet module, a gradient-capable RF probe, compact spectrometer electronics, and a quasi-static bypass sampling process for oilfield installation. The revised interpretation framework combines T1, T2, diffusion coefficient, temperature, signal-quality indicators, repeatability checks, and calibration-domain gating. The present work defines a proof-of-concept route, and the validation requirements for online PAM concentration monitoring; final accuracy, repeatability, RMSE, confidence intervals, and field-calibrated acceptance thresholds must still be determined through controlled loop and field tests. Full article

A broadband method for measuring the complex permeability of thin magnetic films using a short-circuited microstrip fixture is presented. The method is based on full one-port offset-short calibration implemented directly in the fixture with a movable shorting wall, reducing sensitivity to coaxial-to-strip transition imperfections and eliminating the need for its precise optimization. Field-dependent normalization to the empty fixture reduces systematic errors from the external magnetic field, and a correction for residual saturated permeability improves retrieval accuracy. The method was validated on Co, supermalloy, and FeCo films on flexible PET substrates. Retrieved spectra agreed well with reference coaxial data and with the spectrum reconstructed from static magnetic measurements. In the present implementation, broadband spectra were obtained from 0.1 to 20 GHz with no significant systematic distortion, indicating that the proposed approach is suitable for accurate broadband characterization of thin magnetic films without reference standards or precise optimization of the coaxial-to-strip transition. Full article

This paper presents a 10 kW outer-rotor field-modulated permanent magnet vernier generator tailored for low-speed direct-drive applications. It employs an outer-rotor Spoke-array configuration, which effectively mitigates the leakage flux between adjacent pole pairs. First, the topology and operating principle of the proposed generator are elaborated. Analytical calculations of key design parameters are then performed to accelerate the modeling process. A systematic parametric sweep is conducted to optimize the motor parameters, based on which a 2D finite element analysis model is established. Comprehensive FEA simulations are carried out to investigate its flux regulation capability, static and dynamic characteristics, and permanent magnet demagnetization risk. The results demonstrate that the Spoke-array permanent magnet array effectively suppresses leakage flux, achieving a volumetric power density of 387.5 kW/m³, and the no-load back electromotive force achieves a peak amplitude of 270 V with a total harmonic distortion as low as 3.7%, which is significantly higher than that of conventional permanent magnet vernier generators. Finally, a 30-slot/23-pole prototype is fabricated and tested. The experimental results show excellent agreement with the simulation predictions, validating the effectiveness of the proposed design. Full article

Iron-based shape memory alloys (Fe-SMAs) have considerable potential for the active strengthening of concrete structures, yet convenient externally applicable non-destructive methods for identifying local fatigue damage under cyclic loading remain limited. To investigate the weak magnetic response of notched Fe-SMA and its correspondence with local damage evolution, static tensile tests and constant-amplitude fatigue tests were conducted on Fe-SMA specimens with a semi-circular notch. Weak magnetic signals were continuously monitored at a fixed point throughout loading, and surface magnetic-field scanning was performed after fracture. Under static loading, the magnetic signal evolved consistently with the deformation response. Under fatigue loading, the fixed-point magnetic signal exhibited a clear three-stage evolution corresponding to the development of residual deformation. Compared with deformation hysteresis loops, magnetic hysteresis loops contained richer information on local damage evolution. After fracture, abrupt changes in the scanned magnetic field coincided with the actual fracture location, and the magnetic anomaly gradually attenuated as the scanning path moved away from the notch. These results indicate that weak magnetic signals can effectively characterise the evolution of local fatigue damage in notched Fe-SMA, with the normal magnetic component showing greater sensitivity to damage localisation and state assessment. Full article

Crustal magnetic fields exert a fundamental control on the structure and dynamics of the Martian ionosphere. In this study, we use in situ ion composition measurements from the MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS) to investigate how crustal magnetic fields modulated the Martian upper atmosphere during the June 2018 global dust storm. By restricting the analysis to a narrow range of solar zenith angles and altitudes, we isolate magnetic effects from variations driven by solar illumination and vertical structure. We find that the densities of O₂⁺, O⁺, and CO₂⁺ differ systematically between regions of strong and weak crustal magnetic fields, with strong-field regions exhibiting reduced variability consistent with magnetic confinement. Importantly, a substantial fraction of observations located outside traditional geographic masks display ion composition signatures that closely resemble those observed in strong-field regions. Spatial analysis shows that these “strong-like” undetermined observations preferentially occur near known crustal magnetic anomalies, indicating that magnetic influence extends beyond fixed geographic boundaries. These results demonstrate that ion composition provides a sensitive diagnostic of magnetic topology at Mars and reveal the importance of magnetic connectivity in regulating ionospheric structure under extreme atmospheric conditions. Our findings suggest that static geographic classifications may underestimate the true spatial reach of crustal magnetic control during periods of enhanced atmospheric disturbance. Full article

Interbody cages are employed in spinal surgery to enhance segmental stability and facilitate decompression of the spinal cord and nerve roots. As these devices are commonly made of titanium, they produce metal-induced artifacts during postsurgical magnetic resonance (MR) imaging. This study aims to provide a descriptive comparison of five titanium interbody cage prototypes regarding the spatial extent of signal loss artifacts produced during MR imaging under phantom conditions. Five cage prototypes, 3D-printed from a titanium alloy, were imaged using a 3.0 T MR system in accordance with the F2119-07 standard of the American Society for Testing and Materials (ASTM), with advanced metal artifact reduction applied. The cages had identical external geometries but differed in metal volume, contact surface, layout, porosity, and, when applicable, hole geometry. The extent of the studied artifacts demonstrated high to very high repeatability and good to excellent reliability across all MR imaging settings. The quantified extent of signal loss artifacts was lowest for the cage prototype with a solid frame and an interior net structure. Under specific phantom MR imaging conditions, the porous cage with a frame-net layout, but without a centrally positioned hole, produces signal loss artifacts with the smallest spatial extent, which may be advantageous. However, the potential clinical translation of these findings is limited and requires future investigation. Full article

This study comparatively investigates the efficacy of two natural, plant- and microbe-derived polysaccharides—xanthan gum (XG) and guar gum (GG)—in enhancing the water stability and shear strength of granite residual soil (GRS). GRS specimens treated with varying dosages of XG and GG were cured for 14 days and subsequently evaluated through direct shear and static-water disintegration tests. Concurrently, scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (LF-NMR) were employed to elucidate the underlying microstructural and pore-scale mechanisms. Direct shear test results indicate that the peak shear strength reached 295.9 kPa (2.0% GG) and 221.0 kPa (1.5% XG), representing increases of 58.2% and 35.7%, respectively. Quantitatively, GG and XG treatments yielded maximum internal friction angle improvements of 52.96% and 39.37%, with peak cohesion increases of 55.27% and 35.7%, respectively. During static-water immersion, the untreated GRS suffered complete disintegration within 200 s. In contrast, the 2.0% GG- and XG-treated specimens preserved overall structural integrity for 24 h. SEM observations revealed that XG and GG reconstruct the soil fabric by forming encapsulating films and interparticle bridging structures. Finally, LF-NMR analysis provided definitive quantitative proof of a “pore refinement” effect, where biopolymer treatment shifted the primary $T_2$ peaks from 4.64 ms to 3.51 ms. Notably, at a 2.0% dosage, dramatic NMR signal surges (up to 747.5 a.u. for XG and 704.3 a.u. for GG) revealed that excessive biopolymers tend to form localized ‘gel lumps’ rather than uniform films. These blobs weaken the biting force between soil particles, thereby accounting for the observed degradation in shear strength. Full article

I analyze the nonlinear Hamiltonian equations of motion for a one-dimensional chain of transverse magnetic nano-islands, seeking solutions for different types of static domain walls (DWs) connecting uniform static states. The system of elongated magnetic islands oriented transverse (y-direction) to the chain direction (x-direction) experiences an applied magnetic field transverse to the chain. The macro-spin model includes dipole interactions between islands, their uniaxial and easy-plane anisotropies, and Oersted energy of the applied field. DWs can form most easily between pairs of degenerate uniform states, described by their local magnetizations as oblique, y-parallel, and y-alternating. The DWs between oblique states are well described with scalar ${\phi }^4$ theory. General DW structures are found via a numerical energy relaxation scheme. At some anisotropy and field parameters, nearest-neighbor dipole interactions drive antiferromagnetic order inside the DW itself. Full article

The intense low-frequency magnetic field generated by the Electromagnetic Aircraft Launch System (EMALS) during operation poses a serious EMI threat to electronic equipment within carrier-based aircraft nacelles. To address this, a three-dimensional transient finite element model of a long-primary double-sided linear induction motor is established. Using a quasi-static equivalent method, the 118 Hz magnetic field distribution inside and outside a typical engine nacelle is characterized. Results indicate that due to the skin depth significantly exceeding material thickness, the eddy-current shielding of the aluminum alloy nacelle is inadequate, producing internal field intensities that far exceed standard limits and directly threaten sensitive onboard electronics. Based on the magnetic shunting principle, a composite shielding strategy is proposed: applying a flexible high-permeability coating on the nacelle surface to attenuate the overall field, supplemented by local permalloy shields for core equipment. Simulation verification demonstrates that this approach reduces the internal field to safe levels. It achieves effective shielding performance while balancing engineering feasibility with lightweight requirements, providing a viable pathway for ensuring the reliable protection of carrier-based aircraft in intense electromagnetic environments. Full article

The static magnetic field from large seafloor exploration platforms severely interferes with weak geological signals. Accurately predicting and compensating for this interference is critical for deep-sea surveys. However, traditional inversion methods using limited spatial measurements have severely ill-posed coefficient matrices, amplifying near-field noise and causing massive divergence during far-field extrapolation. To address this, we propose a reliable and data-efficient magnetic field prediction method utilizing prior-constrained boundary integrals. First, a virtual plane is constructed between the platform and the measurement plane. A differential recursive algorithm extracts the local magnetic field on this plane from limited measurements to serve as physical prior information. Incorporating this knowledge to structurally constrain the boundary integral inversion fundamentally mitigates the ill-posed problem. Simulations and scaled physical experiments demonstrate that this method prevents near-field noise overfitting, achieving enhanced far-field reliability. By maximizing the utility of limited spatial data, the maximum relative error on the far-field prediction plane is reduced from 10.5% to 8.3% in simulations, and from 13.2% to 9.8% in physical experiments. This provides a highly reliable approach for marine magnetic interference compensation. Full article

Superhydrophobic fiber films, as a typical superhydrophobic material, have advantages such as self-cleaning, non-wettability, and pollution resistance. They can be widely used in oil-water separation, antibacterial, anti-pollution, anti-icing, and self-cleaning fields. Traditional electrospun superhydrophobic fiber films face difficulties in fabricating fibers with large contact angles due to the non-Newtonian fluid flow and Taylor cone jet trajectory limitations. To address this challenge, this study develops a novel ultrasonic-magnetic field coupling electrospinning strategy for fabricating poly(methyl methacrylate)-polystyrene (PMMA-PS) fibrous films with enhanced superhydrophobicity. Physical, chemical, and contact angle measurements were used to analyze the morphology, composition, and hydrophobic properties of the fabricated films. The results showed that by controlling the blend ratio of PMMA and PS and optimizing the electrospinning process with ultrasonic vibration and magnetic field coupling, PMMA-PS fibers with better fiber refinement, closer spindle-shaped arrangements, and significantly increased roughness were successfully fabricated. When using 15% PMMA and 15% PS solutions, the static contact angle of the resulting fiber films reached 173.1°, demonstrating the best superhydrophobicity. The study suggests that optimizing the surface morphology of the nanofibers is an effective method to improve hydrophobicity and provides a new approach for fabricating superhydrophobic fiber films. Full article

Objective: To report on a series of three cases in which problems with rotating magnets (blocked rotation, demagnetization) occurred in cochlear implants and to resolve these problems without surgical intervention. Methods: Of the 3635 devices with rotating magnets implanted at this tertiary referral hospital, 2 exhibited rotation blockage (associated with misalignment of the coil or audio processor), and 1 was partially demagnetized in a 1.5 T MRI scanner. Results: One blockage resolved spontaneously without intervention. The second blockage was resolved in the static field of a 3T MRI scanner, where the demagnetized magnet was also re-magnetized to its original strength. Surgical intervention or re-implantation was not necessary in either case. Conclusions: Surgical intervention or re-implantation is not primarily required in the event of problems with the rotating implant magnet. Prior to surgery, technical analysis can lead to a conservative solution. Full article

External stray magnetic fields from permanent magnet synchronous motors (PMSMs) may cause electromagnetic interference to nearby equipment and limit their application in space-constrained systems. To address this issue, this paper investigates the use of laminated Co-based amorphous ribbon shields for stray-field suppression. An efficient equivalent modeling method is proposed for the simulation of such multilayer thin shielding structures, in which the laminated shield is replaced by an equivalent single-layer model while preserving its macroscopic shielding behavior. The method is first assessed in 2-D through comparisons between refined laminated and simplified equivalent models under both linear permeability and nonlinear magnetization-curve descriptions, and is then extended to 3-D PMSM shielding analysis under static and rotating no-load conditions with experimental validation. Results show that the 10-layer amorphous ribbon shield, with a total thickness of 420 μm, achieves a maximum shielding effectiveness of 7.9 dB at a measurement distance of two motor radii. The maximum deviation between simulation and experiment is 7.4%, and the equivalent model reduces computation time by 28% relative to the refined model. This method provides an accurate and efficient approach for the analysis and design of compact low-frequency magnetic shields for PMSMs. Full article