Combination Of Magnetic Fields Research Articles

Impact of combined electric and magnetic fields on the physical properties of GaAs variant quantum ring quarter cross-section in presence of an off-center shallow donor impurity

Impact of combined electric and magnetic fields on the physical properties of GaAs variant quantum ring quarter cross-section in presence of an off-center shallow donor impurity

Boosting the Efficiency of Photoactive Rod-Shaped Nanomotors via Magnetic Field-Induced Charge Separation.

Photocatalytic nanomotors have attracted a lot of attention because of their unique capacity to simultaneously convert light and chemical energy into mechanical motion with a fast photoresponse. Recent discoveries demonstrate that the integration of optical and magnetic components within a single nanomotor platform offers novel advantages for precise motion control and enhanced photocatalytic performance. Despite these advancements, the impact of magnetic fields on energy transfer dynamics in photocatalytic nanomotors remains unexplored. Here, we introduce dual-responsive rod-like nanomotors, made of a TiO2/NiFe heterojunction, able to (i) self-propel upon irradiation, (ii) align with the direction of an external magnetic field, and (iii) exhibit enhanced photocatalytic performance. Consequently, when combining light irradiation with a homogeneous magnetic field, these nanomotors exhibit increased velocities attributed to their improved photoactivity. As a proof-of-concept, we investigated the ability of these nanomotors to generate phenol, a valuable chemical feedstock, from benzene under combined optical and magnetic fields. Remarkably, the application of an external magnetic field led to a 100% increase in the photocatalytic phenol generation in comparison with light activation alone. By using various state-of-the-art techniques such as photoelectrochemistry, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance, we characterized the charge transfer between the semiconductor and the alloy component, revealing that the magnetic field significantly improved charge pair separation and enhanced hydroxyl radical generation. Consequently, our work provides valuable insights into the role of magnetic fields in the mechanisms of light-driven photocatalytic nanomotors for designing more effective light-driven nanodevices for selective oxidations.

Weak Magnetic Fields Regulate the Ability of High Dilutions of Water to Enhance ROS Production by Neutrophils

The influence of magnetic fields on the physico–chemical properties of water and aqueous solutions is well known. We have previously shown that weak combined magnetic fields with a 60 µT static component and a 100 nT (at 12.6 Hz) variable component are able to activate neutrophils, both directly and indirectly, through water pre-incubated in these fields. The ability to influence the activity of neutrophils was retained in serial dilutions of water, but only when a mechanical effect (shaking) was applied at each dilution step. Here, we confirm that combined magnetic fields are required for the formation of the stimulatory activity of water on ROS production by neutrophils. For the first time, we determined the threshold values of a constant magnetic field (at least 350–550 nT) necessary to maintain this activity in a series of successive dilutions. Additionally, the biophysical properties of various dilutions appeared to be not identical. This confirms that the number of technological steps (successive dilutions with physical influence) is a key factor that determines the activity of highly diluted samples.

Machining of micro-hole on nitinol alloy by UV-MFEDM process

ABSTRACT Nitinol alloy is widely utilized across various industries due to its special properties. In this paper, the compound effects of two kinds of energy fields on material removal rate (MRR), hole wall quality, machining accuracy, and recast layer in ultrasonic combined magnetic field assisted EDM (UV-MFEDM were studied and analyzed. In addition, the influence of magnetic field intensity on the efficiency and accuracy of micro-hole machining is analyzed systematically. The results show that the surface quality of the micropore is significantly improved, the MRR is increased by 31.6%, the taper of the micropore is reduced by nearly 30%, the overcut diameter is reduced by nearly 23%, the recast layer is more uniform and the thickness of the recast layer is reduced by nearly half. Appropriate magnetic field intensity proves beneficial for improving micro-hole machining efficiency while reducing both taper angle and diameter overcut of micro-holes.

Black hole in a combined magnetic field: Ionized accretion disks in the jetlike and looplike configurations

Black hole in a combined magnetic field: Ionized accretion disks in the jetlike and looplike configurations

Assessing efficacy of comprehensive medical rehabilitation of patients with polypoid rhinosinusitis on the basis of correlation adaptometry method

The article discusses the algorithm for using the method of correlation adaptometry to assess the effectiveness of medical rehabilitation of patients with polypoid rhinosinusitis. It is shown that this method is highly informative and allows researchers to objectify the results of complex medical rehabilitation of patients with polypoid rhinosinusitis, evaluating the efficacy from the standpoint of the key categories of restorative medicine that reflect the patient’s regulatory capabilities for the formation and implementation of the increased adaptive capabilities of the body. The obtained results prove the maximum efficiency of medical rehabilitation based on the complex use of the drug dupilumab and the course application of the alternating magnetic field in combination with low-intensity laser therapy, the complementary therapeutic activity of which ensures the maximum manifestation of sanogenetic processes aimed at normalizing the structural and functional parameters of the nasal mucosa and paranasal sinuse.

On the sign of the linear magnetoelectric coefficient in Cr2O3

We establish the sign of the linear magnetoelectric (ME) coefficient, α, in chromia, Cr2O3. Cr2O3 is the prototypical linear ME material, in which an electric (magnetic) field induces a linearly proportional magnetization (polarization), and a single magnetic domain can be selected by annealing in combined magnetic (H) and electric (E) fields. Opposite antiferromagnetic (AFM) domains have opposite ME responses, and which AFM domain corresponds to which sign of response has previously been unclear. We use density functional theory (DFT) to calculate the magnetic response of a single AFM domain of Cr2O3 to an applied in-plane electric field at zero kelvin. We find that the domain with nearest neighbor magnetic moments oriented away from (towards) each other has a negative (positive) in-plane ME coefficient, α⊥ , at zero kelvin. We show that this sign is consistent with all other DFT calculations in the literature that specified the domain orientation, independent of the choice of DFT code or functional, the method used to apply the field, and whether the direct (magnetic field) or inverse (electric field) ME response was calculated. Next, we reanalyze our previously published spherical neutron polarimetry data to determine the AFM domain produced by annealing in combined E and H fields oriented along the crystallographic symmetry axis at room temperature. We find that the AFM domain with nearest-neighbor magnetic moments oriented away from (towards) each other is produced by annealing in (anti-)parallel E and H fields, corresponding to a positive (negative) axial ME coefficient, α∥ , at room temperature. Since α⊥ at zero kelvin and α∥ at room temperature are known to be of opposite sign, our computational and experimental results are consistent.

Combination of magnetic field and ultraviolet for fouling control in saline wastewater distribution systems

Fouling is a significant challenge for recycling and reusing saline wastewaters for industrial, agricultural or municipal applications. In this study, we propose a novel approach of magnetic field (MaF) and ultraviolet (UV) combined application for fouling mitigation. Results showed, combination of MaF and UV (MaF-UV) significantly decreased the content of biofouling and reduced the complexity of microbial networks, compared to UV and MaF alone treatments. This was due to MaF as pretreatment effectively reduced the water turbidity, improve the influent water quality of UV disinfection and increases UV transmittance, eliminating the adverse impacts of UV scattering and shielding, hence increased the inactivation effectiveness of UV disinfection process. MaF assisted UV also reduced the abundance of UV-resistant bacteria and inhibited the risk of bacterial photoreactivation and dark repair. Meanwhile, MaF-UV drastically reduced the contents of precipitates and particulate fouling by accelerating the transformation rate of CaCO3 crystal from compact calcite to loosen hydrated amorphous CaCO3, and enhancing the flocculation process. These findings demonstrated that MaF-UV is an effective anti-fouling strategy, and provide insights for sustainable application of saline wastewaters.

Evaluation of the results of complex medical rehabilitation of patients with polyposis rhinosinusitis in the long-term period

BACKGROUND: Previous studies on the comparative evaluation of the effectiveness of the course application of therapeutic physical factors during the complex medical rehabilitation of patients with polypous rhinosinusitis showed a rather high efficiency of the additional use of complex physiotherapy (alternating magnetic field and low-intensity laser therapy) in enhancing the regression of the main clinical manifestations of polypous rhinosinusitis and improving the quality of life (QoL) of patients. Considering the chronic and often recurrent nature of polypous rhinosinusitis, along with the relief of the main clinical manifestations of the disease and improvement in the quality of life of patients after treatment, medical rehabilitation of patients should also cover the long-term period.
 AIM: Evaluation of the results of complex medical rehabilitation of patients with polyposis rhinosinusitis in the long-term period (after 6, 12 and 18 months) and determination of the optimal time parameters for a repeated course of physiotherapy aimed at maintaining the achieved clinical effect and the level of quality of life of patients.
 MATERIALS AND METHODS: The study was performed with the participation of 120 patients with moderate to severe polypous rhinosinusitis and uncontrolled course. All patients were divided into 4 groups by simple fixed randomization. The first group (control, 30 patients) received only basic therapy, including endonasal application of Nasonex 2 doses 2 times a day and daily twice daily lavage of the nasal mucosa. Patients of the second group (comparison group 1, 30 patients) were additionally injected subcutaneously with dupilumab at a dose of 300 μg once every two weeks. In the third group (comparison group 2, 30 patients), against the background of the administration of dupilumab, exposure to an alternating magnetic field was performed. using the apparatus MAGNIT Med TeCo. Patients of the fourth group (main group, 30 patients), in addition to the volume of treatment of patients of the third group, received low-intensity laser radiation of the red spectrum (633 nm) using the AZOR-2K-02 apparatus.
 RESULTS: Positive dynamics in terms of assessed clinical indicators throughout the entire observation period was noted only in the comparison groups and the main group. The maximum severity of positive changes was determined in the main group after 6 and 12 months of rehabilitation, exceeding the achieved values in the group with dupilumab. The follow-up period made it possible to establish that 18 months after the start of rehabilitation, there were no significant differences between these groups. The dynamics of the parameters of the microcirculatory tissue system in the comparison groups and the main group in the long-term period indicated the formation of compensatory-adaptive processes aimed at eliminating congestion in the nasal mucosa and associated hypoxia, as well as the normalization of oxygen metabolism and trophism of tissues prone to chronic inflammation.
 CONCLUSION: The results obtained convincingly prove the effectiveness of additional course use of an alternating magnetic field in combination with low-intensity laser therapy. The use of this technology, implemented against the background of ongoing biological therapy, shows its increased efficiency up to 12 months after the start of medical rehabilitation. It is advisable to conduct a second course of physiotherapy based on the complex use of an alternating magnetic field and low-intensity laser radiation 9–12 months after the start of medical rehabilitation.

Modeling magnetic field and strain driven phase transitions and plasticity in ferrous metals

AbstractA finite strain continuum theory is advanced for static and dynamic simulations of material response under combined mechanical and magnetic fields. The general thermomechanical theory accounts for nonlinear thermoelasticity, plastic flow from slip and twinning, damage mechanics, and phase transformations. Maxwell's equations are implemented in the Galilean approximation. Effects of electromechanical body forces, Maxwell's stress, and magnetostriction are included, as are forces and heating from electric currents in conductors. Several assumptions are newly introduced to facilitate calculations in the context of finite element methods with explicit dynamics. Of particular interest are ferrous solids whose phase changes and interactions are affected by external magnetic fields. Predictions for compression of pure iron, in comparison with experimental data and prior analytical results, verify suitability of modeling assumptions and numerical methods. Further calculations demonstrate efficacy of the model for reproducing experimental findings on ferrous alloys of the same chemical composition but with two different prior heat treatments, leading to different initial microstructures. For all materials studied, effects of magnetic field on kinetic barriers are discovered to be more influential on phase transitions than magnetic Gibbs free energy differences between phases.

Fabrication of high permeability and antifouling composite membrane loaded with Fe3O4 nanoparticles via a magnetic field induced phase separation

Membrane fouling increases operational expenses and limits the application of ultrafiltration technology in water treatment. To mitigate the membrane fouling, this study incorporated Fe3O4 nanoparticles (NPs) into the polyethersulfone (PES) membrane casting solution, and developed a non-solvent induced phase separation (NIPS) method assisted by a magnetic field (MGF) to fabricate the Fe3O4 NPs composite ultrafiltration membrane. The combination of MGF and Fe3O4 NPs synergistically enhanced the permeability and separation performance of the composite membrane. The performance of the membrane was determined by its structure. With the involvement of MGF, Fe3O4 NPs were enriched on the surface layer of the membrane, resulting in enhanced hydrophilicity of the composite membrane. The membrane permeability increased to 913.39 LMH·bar−1, and the rejection performance rose to 93 % due to the formation of tiny pores on the membrane surface that facilitated solvent diffusion during phase separation, thereby counteracting the adverse effects of heightened viscosity in the casting solution. Moreover, the Fe3O4 NPs composite membrane fabricated with MGF induction exhibited significantly enhanced antifouling capability in multi-cycle fouling tests, resulting in a 27.5 % increase in specific flux compared to the pure PES membrane. Additionally, the preparation procedures for the matrix membrane were optimized to include 15 wt% PES, 3 wt% PVP, and a pre-treatment time of 30 s. These findings have significant implications for advancing the widespread application of membrane technology.

Plaquette Singlet Transition, Magnetic Barocaloric Effect, and Spin Supersolidity in the Shastry-Sutherland Model.

Inspired by recent experimental measurements [Guo etal., Phys. Rev. Lett. 124, 206602 (2020PRLTAO0031-900710.1103/PhysRevLett.124.206602); Jiménez etal., Nature (London) 592, 370 (2021)NATUAS0028-083610.1038/s41586-021-03411-8] on frustrated quantum magnet SrCu_{2}(BO_{3})_{2} under combined pressure and magnetic fields, we study the related spin-1/2 Shastry-Sutherland model using state-of-the-art tensor network methods. By calculating thermodynamics, correlations, and susceptibilities, we find, in zero magnetic field, not only a line of first-order dimer-singlet to plaquette-singlet phase transition ending with a critical point, but also signatures of the ordered plaquette-singlet transition with its critical end point terminating on this first-order line. Moreover, we uncover prominent magnetic barocaloric responses, a novel type of quantum correlation induced cooling effect, in the strongly fluctuating supercritical regime. Under finite fields, we identify a quantum phase transition from the plaquette-singlet phase to the spin supersolid phase that breaks simultaneously lattice translational and spin rotational symmetries. The present findings on the Shastry-Sutherland model are accessible in current experiments and would shed new light on the critical and supercritical phenomena in the archetypal frustrated quantum magnet SrCu_{2}(BO_{3})_{2}.

A combined magnetic field stabilization system for improving the stability of 40Ca+ optical clock

Future applications of portable 40Ca+ optical clocks require reliable magnetic field stabilization to improve frequency stability, which can be achieved by implementing an active and passive magnetic field noise suppression system. On the one hand, we have optimized the magnetic shielding performance of the portable optical clock by reducing its apertures and optimizing its geometry; on the other hand, we have introduced an active magnetic field noise suppression system to further suppress the magnetic field noise experienced by the ions. These efforts reduced the ambient magnetic field noise by about 10000 times, significantly reduced the linewidth of the clock transition spectrum, improved the stability of the portable 40Ca+ optical clock, and created the conditions for using portable optical clocks in non-laboratory magnetic field environments. This active magnetic field suppression scheme has the advantages of simple installation and wide applicability.

The effects of external magnetic fields on the flow and heat transfer in a three-dimensional microchannel

In this study, the thermal and flow characteristics in a U-type microchannel have been investigated and compared under the influence of single and combined magnetic fields. The effects of various Reynolds numbers Hartmann numbers and nanoparticle volume fractions are examined. It is found that selecting the appropriate arrangement of applying single and combined magnetic fields plays an essential role in microchannel thermal performance and fluid flow behavior. Under the influence of some combined magnetic fields, a secondary flow is applied to the primary flow and affects the flow and heat transfer. The Nusselt number under the influence of the applied magnetic field(s) increases up to 137.7% or even decreases down to 25.5% compared to that without the magnetic field for various conditions. Results show that the combined magnetic fields usually provide better thermal performance than that of the single one.

Dynamic resistance and voltage response of a REBCO bifilar stack under perpendicular DC-biased AC magnetic fields

The dynamic resistance of REBCO (REBa2Cu3O7-d, RE stands for rare earth), coated conductors (CCs) is a key parameter in many high-temperature superconductor applications where CCs carry DC currents exposed to AC and DC magnetic fields, such as field-triggered persistent current switches, flux pumps, and fault current limiters. In this work, dynamic resistance and dynamic voltage have been studied via experiments and finite element method (FEM) simulations in a REBCO bifilar stack at 77 K, under combined AC and DC magnetic fields with different magnitudes, frequencies, and waveforms. Our results show some distinct features of dynamic resistance and voltage from those under pure AC magnetic fields. With an increasing DC magnetic field, the dynamic resistance exhibits an obvious linearity with the applied AC magnetic field, and becomes less dependent on the AC field frequency. The fundamental frequency of the dynamic voltage under a DC magnetic field becomes the same as that of the applied AC field, which completely differs from the pure AC field case where the fundamental frequency doubles. For the first time, instantaneous threshold field (B th) values are obtained from the dynamic voltage, which are substantially different in the field-increasing and field-decreasing processes. These key differences are attributed to the dominant role of DC magnetic fields in determining the critical current of the superconductor, which significantly dwarfs the influence of AC fields. These new discoveries may help researchers better understand the electromagnetism of superconductors and be useful for relevant applications.

Radiative corrections to the level width in the presence of magnetic field

The effect of a constant magnetic field in combination with a field induced by an external thermal environment on atomic decay rates is studied. For this purpose, radiative corrections including magnetic interaction are considered for hydrogen and hydrogen-like ions with a small nuclear charge Z. Corrections to the decays of the metastable state 2s and the excited state 2p were calculated at various magnetic field strengths suitable for the conditions of the laboratory experiments. It is found that the combination of the magnetic field and thermal environment can lead to a broadening close to the level of experimental error, which makes it necessary to take them into account in the near future.

Sustainable irrigation of pipeline fluid flow rate regulation based on traveling wave magnetic field

To adjust the flow rate of liquid in the pipeline in real-time in the process of crop drip irrigation, to achieve sustainable agricultural irrigation. This paper designs and develops a kind of liquid speed-regulating device for drip irrigation based on traveling wave magnetic field. This paper aims to use the electromagnetic driving force generated by the traveling wave magnetic field to realize the soft control of liquid flow rate in drip irrigation pipelines. First of all, the structure of the combined traveling wave magnetic field generator was designed. COMSOL physical field simulation software was used to build the traveling wave magnetic field simulation model, and the magnetic field distribution diagram and the variation curve of the magnetic field intensity were generated in the time domain. Then, through the analysis of the simulation model, the harmonic interference of a single row and combined traveling-wave magnetic field generator is compared, and the optimal spacing between the traveling-wave magnetic field generator units is determined. Finally, the water-fertilizer fusion liquid used in the process of agricultural irrigation was selected and the liquid speed regulation experiment was carried out. The experimental results show that the combined liquid speed regulating device can effectively reduce the number of traveling wave field harmonics, compared with the single wave field generator at the same power, the magnetic field intensity is increased by 33.9 %. When the excitation current is 2 A and the initial flow rate is 0.5 m/s, the device can increase the flow rate of water-fertilizer fusion liquid for agricultural drip irrigation by 2.27 % and decrease by 2.13 %, which can meet the real-time and effective speed regulation requirements of water-fertilizer fusion liquid in the process of agricultural drip irrigation.

Hybrid NV Center Magnetometer With Directional Vector Resolution Based on Magnetic Flux Concentrators

Since the introduction of Hall magnetometers, different types of magnetometers have been widely used. Among them, magnetometers based on nitrogen-vacancy (NV) centers in diamonds are promising room-temperature solid-state sensors. Their sensitivity to low-frequency (< 10 Hz) magnetic fields has been reported to be currently at the nT level. Still, limitations in the detectable spatial range hinder their potential applications in medical imaging, earth sciences, and navigation. The most recent sensitivity enhancement technique involves using high-permeability flux concentrators with a unique magnetic field amplification structure that can cause the NV magnetometer to lose its vector detection capabilities. To address this limitation, we proposed a hybrid magnetometer based on a diamond-based hetero-NV center, which collects magnetic flux over a larger area and concentrates it in the diamond magnetometer, from which the magnetic field vector can be calculated by measuring the specific magnetic field direction vector. The low-frequency sensitivity of 90 pT∙Hz-1/2 under conventional ambient conditions has been solved by inserting NV-doped diamond blocks between four permalloy concentrators in a triangular structure, which solves the vector deficiency problem of traditional magnetic concentrators. High-sensitivity real-time variation acquisition of the magnetic field signal has been achieved by applying an AC magnetic field in combination with modulation and demodulation methods.

Reversible conversion between skyrmions and skyrmioniums

Skyrmions and skyrmioniums are topologically non-trivial spin textures found in chiral magnetic systems. Understanding the dynamics of these particle-like excitations is crucial for leveraging their diverse functionalities in spintronic devices. This study investigates the dynamics and evolution of chiral spin textures in [Pt/Co]3/Ru/[Co/Pt]3 multilayers with ferromagnetic interlayer exchange coupling. By precisely controlling the excitation and relaxation processes through combined magnetic field and electric current manipulation, reversible conversion between skyrmions and skyrmioniums is achieved. Additionally, we observe the topological conversion from a skyrmionium to a skyrmion, characterized by the sudden emergence of the skyrmion Hall effect. The experimental realization of reversible conversion between distinct magnetic topological spin textures represents a significant development that promises to expedite the advancement of the next generation of spintronic devices.

Investigation of the collective effects in the cosmic Zevatron based on cyclotron auto-resonance by preliminary particle-in-cell simulations

Cyclotron autoresonance acceleration has been recently advanced as a potential mechanism for accelerating nuclei to ZeV energies (1 ZeV = 1021 eV). All results have been based on single- and many-particle calculations employing analytic solutions to the relativistic equations of motion in the combined magnetic and radiation fields, excluding effects related to the particle-particle interactions. Here, results from preliminary many-particle calculations and preliminary Particle-In-Cell (PIC) simulations, are presented which lend support to the single-particle investigations. Each single-particle result is found to lie well within one standard deviation about the ensemble average obtained from the corresponding many-particle calculation. The PIC simulations show that, even for number densities far exceeding those employed in the non-interacting case, the energy gain drops markedly due to the collective effects, over the first ∼8 mm of the acceleration length. Together with the substantial attenuation, this finding supports the conclusion that the particle-particle interaction effects can be negligibly small over acceleration lengths of typically many kilometers.