Effect Of Magnetic Field Research Articles

Examining the influence of magnetic field on a donor dopant’s photoionization cross-section in a double quantum box

This study systematically explored the binding energy and the photoionization cross-section (PCS) of a hydrogenic shallow donor impurity within a GaAs double quantum box structure incorporated into a Ga(1−x)Alx As matrix under the influence of an external intense magnetic field. The computations are performed using the effective-mass approximation (EMA) and the finite element method (FEM), taking into account a finite potential across all surfaces of the nanosystem. The results emphasize the significant role of the magnetic field, primarily in enhancing the donor binding energy within the double quantum box system. We demonstrate that increasing the magnetic field results in an augmentation of binding energy across various aluminum concentrations. The PCS of a shallow donor impurity undergoes a blue shift when shifted from the barrier center to the box center, attributed to the increased binding energy. When the double quantum box is subjected to a magnetic field effect, the amplitude peaks of PCS show an elevation coupled with a blue shift. By setting magnetic field values at 0 T, 35 T, or 70 T and varying aluminum concentrations, we observe a shift in the PCS towards higher energy levels along with an increase in peak amplitude. We also study the PCS of the donor impurity as a function of photon energy, mainly examining the effects of box width and barrier width modifications in the double quantum box.

The effect of magnetic field on the orientational ordering of easy magnetization axes in superparamagnetic nanoparticles

The active use of nanoparticles in modern biomedical applications and technologies requires reliable theoretical models capable of predicting physical properties. The effect of a static magnetic field on the orientational ordering of the easy magnetization axes in an ensemble of superparamagnetic nanoparticles (SNPs) is studied using a combination of statistical-mechanical theory and computer simulations. The magnetic dipole-dipole interaction between particles is taken into account within the framework of the modified mean-field approach. The alignment distributions of the easy magnetization axes of the SNPs and the static magnetic characteristics of the ferrocomposite are analyzed. The presence of even weak interparticle magneto-dipole interactions results in a notable enhancement of the magnetic susceptibility of the ferrocomposite.

MR compatible detectors assessment for a 0.35 T MR-linac commissioning

PurposeTo assess a large panel of MR compatible detectors on the full range of measurements required for a 0.35 T MR-linac commissioning by using a specific statistical method represented as a continuum of comparison with the Monte Carlo (MC) TPS calculations. This study also describes the commissioning tests and the secondary MC dose calculation validation.Material and methodsPlans were created on the Viewray TPS to generate MC reference data. Absolute dose points, PDD, profiles and output factors were extracted and compared to measurements performed with ten different detectors: PTW 31010, 31021, 31022, Markus 34045 and Exradin A28 MR ionization chambers, SN Edge shielded diode, PTW 60019 microdiamond, PTW 60023 unshielded diode, EBT3 radiochromic films and LiF µcubes. Three commissioning steps consisted in comparison between calculated and measured dose: the beam model validation, the output calibration verification in four different phantoms and the commissioning tests recommended by the IAEA-TECDOC-1583.Main resultsThe symmetry for the high resolution detectors was higher than the TPS data of about 1%. The angular responses of the PTW 60023 and the SN Edge were − 6.6 and − 11.9% compared to the PTW 31010 at 60°. The X/Y-left and the Y-right penumbras measured by the high resolution detectors were in good agreement with the TPS values except for the PTW 60023 for large field sizes. For the 0.84 × 0.83 cm2 field size, the mean deviation to the TPS of the uncorrected OF was − 1.7 ± 1.6% against − 4.0 ± 0.6% for the corrected OF whereas we found − 4.8 ± 0.8% for passive dosimeters. The mean absolute dose deviations to the TPS in different phantoms were 0 ± 0.4%, − 1.2 ± 0.6% and 0.5 ± 1.1% for the PTW 31010, PTW 31021 and Exradin A28 MR respectively.ConclusionsThe magnetic field effects on the measurements are considerably reduced at low magnetic field. The PTW 31010 ionization chamber can be used with confidence in different phantoms for commissioning and QA tests requiring absolute dose verifications. For relative measurements, the PTW 60019 presented the best agreement for the full range of field size. For the profile assessment, shielded diodes had a behaviour similar to the PTW 60019 and 60023 while the ionization chambers were the most suitable detectors for the symmetry. The output correction factors published by the IAEA TRS 483 seem to be applicable at low magnetic field pending the publication of new MR specific values.

Non-similar analysis of bio-convective micropolar nanofluid flow including gyrotactic microorganisms across a stretched geometry

This study explores the novel interaction of gyrotactic microorganisms within a two-dimensional bioconvective micropolar nanofluid flow along a stretched surface, employing the Tiwari-Das nanofluid model. Uniquely, blood is modeled as a micropolar fluid incorporating titanium dioxide ( Ti O 2 ) and silver ( Ag ) nanoparticles. The analysis incorporates influential factors such as viscous dissipation, magnetic field, and heat source effects. By converting the control system into dimensionless nonlinear coupled differential equations, a complete understanding of the system is attained through the application of the local non-similarity approach and bvp4c (MATLAB tool). Particularly, the study provides valuable insight into the influence of dimensionless control parameters on key profiles such as velocity, microrotation, temperature, concentration, and microbial profiles. The findings show that temperature, microrotation, and velocity profiles are all improved by raising the values of micropolar parameters. Furthermore, the microbe profile shows an inverse connection with the Lewis number and a positive association with the Peclet number, whereas the concentration profile declines with increasing Schmidt number values. Furthermore, the study provides a quantitative analysis through tables, revealing variations in the drag coefficient and Nusselt number. This innovative exploration sheds light on the unique behavior of micropolar bioconvective nanofluids, offering valuable contributions to the field of fluid dynamics and bioengineering.

Momentum transport of chiral modes in a thermal QCD medium

We investigate the effect of a weak magnetic field on momentum transport in a thermal QCD medium at finite quark chemical potential using a semiclassical kinetic theory. In the presence of a magnetic field, the momentum transport coefficients acquire a tensor structure, reflected by the five shear ([Formula: see text] and [Formula: see text]) and two bulk viscous components ([Formula: see text] and [Formula: see text]). The weak magnetic field removes the degeneracy in the effective mass of flavors, leading to different masses for the left-handed (L) and right-handed (R) chiral modes of quarks. The coefficients, [Formula: see text] and [Formula: see text] decrease with magnetic field in L mode and increase in [Formula: see text] mode, whereas, [Formula: see text] and [Formula: see text] increase in both L and [Formula: see text] modes. The bulk viscous coefficients, [Formula: see text] and [Formula: see text] increase with magnetic field for both L and R modes. The shear and bulk viscous coefficients positively amplify with baryon asymmetry.

On the Electrodeposition of Zinc in Low Magnetic Fields

Abstract While aqueous zinc-based batteries have garnered much research on account of their improved safety, lower cost, and easier fabrication over lithium-ion batteries, they remain held back by dendrite growth on the anode. While many different solutions have been proposed, these solutions often greatly complicate the synthesis or materials in the battery. The application of a magnetic field across the battery has been shown to inhibit dendrite formation without the need for any materials or interface engineering. Herein, we provide a study on the effects of low magnetic fields on the electrodeposition and cycling of zinc in various aqueous systems. We demonstrate that although stronger fields have more immediate impacts on the morphology of zinc deposits, low magnetic fields are still suitable for inhibiting dendrite growth over long periods of cycling. Magnetic field strengths as low as 29 mT were shown to decrease charge transfer resistance of zinc ion deposition by up to 54% and to stabilize the cycling of Zn/Zn symmetric cells. Furthermore, the versatility of magnetic field application was demonstrated by affecting the morphology of zinc deposits on both copper and single-walled carbon nanotubes, which are both compatible with anode-free configurations of aqueous zinc-ion batteries.

Effects of low-frequency magnetic field on solubility, structural and functional properties of soy 11S globulin.

Soy 11S globulin has high thermal stability, limiting its application in the production of low-temperature gel foods. In this study, the low-frequency magnetic field (LF-MF, 5 mT) treatment (time, 30, 60, 90, and 120 min) was used to improve the solubility, conformation, physicochemical properties, surface characteristics, and gel properties of soy 11S globulin. Compared with the native soy 11S globulin, the sulfhydryl content, emulsifying capacity, gel strength, water-holding capacity, and absolute zeta potential values significantly increased (P < 0.05) after LF-MF treatment. The LF-MF treatment induced the unfolding of the protein structure and the fracture of disulfide bonds. The variations in solubility, foaming properties, viscosity, surface hydrophobicity, and rheological properties were closely related to the conformational changes of soy 11S globulin, with the optimum LF-MF modification time being 90 min. LF-MF treatment is an effective method to improve various functional properties of native soy 11S globulin, and this study provides a reference for the development of plant-based proteins in the food industry. © 2024 Society of Chemical Industry.

Dynamics of electron-hole pairs in interface exciplex OLEDs investigated by magnetic field effects

Interface exciplex organic light-emitting diodes (OLEDs) have attracted intense attention due to the advantages including well-confined recombination regions, barrier-free charge transport and thermally activated delayed fluorescence (TADF) characteristics. To investigate the spin evolutions and dynamics of electron-hole (e-h) pairs, such as polaron pairs (PPs) and charge transfer (CT) excitons, in interface exciplex OLEDs is crucial for a better understanding on their energy gain and loss mechanisms. In this work, microscopic dynamics of e-h pairs in interface exciplex OLEDs were investigated by magneto-electroluminescence (MEL) and magneto-conductivity (MC) responses. The interface exciplex OLEDs were fabricated using 4,4,4-tris(N-3-methylphenyl-N-phenylamino) triphenylamine (m-MTDATA) as the donor and 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T) as the acceptor. Hyperfine interaction (HFI)- and different g-factors between electrons and holes (Δg mechanism)-dominated spin flip processes, and recombination and dissociation processes such as triplet-triplet annihilation (TTA) and triplet-charge annihilation (TQA) were identified, and their changes with temperature and current were explored. Our results may provide valuable insights into the evolution of carriers and facilitate the development of interface exciplex-based OLEDs.

The effect of magnetic field on the heat transfer in the porous medium octagonal cavity with Cassini oval barriers

This article investigates the effect of Rayleigh numbers, Hartmann numbers, and magnetic fields on nanofluid flow behavior and heat transfer. The flow behavior has been analyzed based on the contours and values of the flow function and heat transfer based on the temperature distribution contours and local and average Nusselt number values. Since the effects of the magnetic field are an important parameter in many technical and engineering applications such as cooling of nuclear reactors, extraction of geothermal energy, and induction casting of metals, in this study, its effect on aluminum oxide nanoparticle, Al2O3, and water, H2O, has been analyzed. The governing equations of nanofluid flow, continuity, momentum, and energy equations have been solved using the Galerkin finite element method and coded and simulated using FlexPDE software. The results obtained for both octagonal cavities containing horizontal and vertical Cassini oval barriers with specific boundary conditions show that with the Rayleigh number and nanoparticle volume fraction being constant, the value of the maximum stream function decreases with the increase of the Hartmann number, and when the Hartmann number and nanoparticle volume fraction is constant, with increasing Rayleigh number, its value increases significantly.

Исследование изменения геометрических параметров образцов, наплавленных методом GMAW при воздействии на электрическую дугу продольного магнитного поля

Introduction. The paper presents the results of research of additive manufacturing process by electric arc with axial feeding of steel filler wire in protective gas environment (GMAW technology) with additional influence of external longitudinal magnetic field on electric arc. Purpose of work: an experimental study of the effect of a longitudinal magnetic field during additive manufacturing by an electric arc with axial feed of filler wire made of structural steels in a protective gas environment on the change in the geometrical characteristics of the layers being surfaced. Research Methods. The manufacturing of specimens was carried out on a 5-axis additive machine based on a CNC machine. Surfacing was carried out in the following modes: voltage 17.5 V; current 55–65 A; wire diameter 1.2 mm; wire material Sv-08G2S; wire feed rate 2,267 mm/min; approximate roll diameter 3.0 mm; roll length 50 mm; number of wires per one roll 312.5 mm; number of layers when surfacing the wall 5; magnet operation mode: alternating current with frequency 50 Hz, voltage 30 V; measured magnetic induction 5.7 mTl; initial height of the magnet above the substrate 10 mm; electrode stickout 10 mm; shielding gas: welding mixture CO2-Ar; gas pressure (flow rate) 0.15 MPa. Results and discussion. The conducted experimental study showed that the effect of longitudinal magnetic field had a statistically significant effect on the change in the dimensions of the singular, namely an increase in the width of the layers being surfaced by 34.1 %, with a calculated significance index close to zero, and a decrease in height by 20.2 %, with a calculated significance index equal to 2.7105. The effect of longitudinal magnetic field had a statistically significant effect on the change of the overall dimensions of the specimens consisting of five layers, namely, the width of the specimens increased by 11.2 % with a calculated significance index of 4.3103, and the height of the specimens decreased by 10.3 % with a calculated significance index of 6.3105. The effect of longitudinal magnetic field had no statistically significant effect on the change of the vertical deviation from straightness for the side walls of the specimens, with a calculated significance index of 0.3277, and had no statistically significant effect on the change of the error of the width of the walls of the specimens, with a significance index of 0.098.

Numerical simulation of molybdenum disulfide-carbon nanotubes/water hybrid nanofluid flow due to a stretching cylinder: Applications to industrial manufacturing processes

This study delves into the exploration of hybrid nanofluids within the context of a stretching cylinder, a domain that has captivated numerous researchers owing to its pivotal applications in industrial manufacturing processes, particularly in metal forming and stretch dies. The authors, recognizing the significance of these applications, have introduced a novel heat transfer fluid termed hybrid nanofluid, comprising molybdenum disulfide and carbon nanotubes suspended in the base liquid, water. The investigation focuses on the flow of the hybrid nanofluid within a stretching cylinder, considering various influential factors such as Joule heating, thermal radiation, porous medium, and magnetic field effects. To model this complex problem, we employed modified Navier–Stokes equations. Employing similarity transformations, assumptions, and non-dimensional parameters, the problem was effectively simplified. The MATLAB bvp4c technique, a well-established numerical approach, was then employed to solve the resulting mathematical formulation. Graphical representations are presented to illustrate various aspects of the flow, facilitating a comprehensive understanding of the system. Comparisons are drawn among the flow characteristics of mono nanofluid, and the developed hybrid nanofluid. It is noted from the current analysis that the temperature strength increases with higher values of the magnetic field parameter, curvature parameter, radiation parameter, and Eckert number in both fluid cases. The Nusselt number increases with higher values of Prandtl number and thermal relaxation parameter. The identified patterns in velocity distribution, temperature strength, and fluid behavior provide a valuable foundation for optimizing thermal efficiency in diverse industrial applications. By leveraging the insights gained from this research, manufacturers can make informed decisions to enhance heat transfer processes, particularly in areas such as metal forming and stretch dies.

Investigation of the Effect of Magnetic Field and Propellant on Hall Thruster’s Stability via a 0D Model

Hall thrusters are plasma-based devices that have established themselves as one of the most attractive and mature electric propulsion technologies for space applications. These devices often operate in a regime characterized by low frequency, large amplitude oscillations of the discharge current, which is commonly referred to as the ‘breathing mode’. The intensity of these oscillations depends on the thruster’s design and operating conditions and can reach values of the order of the average discharge current, posing issues for the thruster’s performance and for coupling with the driving electronics. A 0D model of the thruster discharge was developed to investigate the core physical mechanisms leading to the onset and sustenance of the breathing mode. The model was found to be capable of reproducing oscillations with characteristics in line with those observed in the breathing mode. In this work, we extend the use of the 0D model to investigate the effect of the magnetic field intensity and of different propellants on the system stability.

Insight into the mechanisms of combining direct current magnetic field with phosphate in promoting emulsifying properties of myofibrillar protein

This study investigated the combined effects of direct-current magnetic field (DC-MF, 9.5 mT) and tetrasodium-pyrophosphate (TSPP, 1-5 g/L) on emulsified gel properties of porcine myofibrillar protein (MP). Results showed that MP at DC-MF and 3 g/L TSPP had decreased spectrum intensity of UV and fluorescence compared to that without DC-MF, owing to the changes of MP tertiary structure caused by DC-MF, especially tryptophan and tyrosine. The emulsion treated with DC-MF behaved better emulsifying activity and stability than that without DC-MF under such condition. And emulsion had lower creaming index and better storage stability. Gels prepared by this MP emulsion had low porosity and stable structure, accompanying with smaller size and more uniform distribution of oil droplets. Microstructure images showed that gels were covered with microporous structure, which was conducive to the good WHC of the emulsified gels (97.12%). These results showed the feasibility of DC-MF and TSPP in improving MP emulsion/emulsified gel.

Time dependent magnetic field effects on the MHD flow and heat transfer in a rectangular duct

AbstractWe consider the effect of time dependent magnetic field on the natural convection magnetohydrodynamic flow in a rectangular duct. The flow is two‐dimensional, unsteady, laminar and the fluid is electrically conducting and incompressible. The heat transfer is taken into account using the Boussinesq approximation and the buoyancy force is included in the momentum equations for the thermal coupling. The flow is considered at low magnetic Reynolds number setting and hence, the induced magnetic field is neglected. The proposed model in which the governing equations are given in terms of stream function, vorticity and temperature, is approximated by using a Chebyshev spectral collocation method for the spatial discretisation coupled with a backward difference scheme that is unconditionally stable for the temporal integration. The flow and heat transfer characteristic are analysed for several definitions of applied time varying magnetic field. Increase of the Hartmann number and the time variation of the applied magnetic field, changes the flow behaviour, especially at transient time levels and at the steady‐state.

Magnetic field effects in laser wakefield excitation: a study using Hermite–Gaussian laser pulses in homogeneous plasma

Magnetic field effects in laser wakefield excitation: a study using Hermite–Gaussian laser pulses in homogeneous plasma

Comparative study of low magnetic field effects in finger-finger and finger-split gate single electron pumps

Single Electron Pump (SEP) devices that can deliver single electrons at high frequencies are fabricated using two different gate geometries. The pump quantum dot (QD) can be defined either using two finger gates where the pump operates in what is known as the conventional pumping regime (CPR), or alternatively, the QD can be designed with the use of a single finger gate and split gate, where the pump operates in the long pumping regime (LPR). Here we investigate pump-maps produced in both the CPR and LPR under the effects of a low magnetic field (1 T to −1 T) and observe both the evolution of the pump-map and pump accuracy. Measurements were carried out in a cryogen free dilution refrigeration system with the use of a superconducting magnetic. Clear discrepancies between the behaviour of current in the different regimes can be seen indicating a fundamental difference in the operation of the pumps in the two different pumping regimes.

Evolution of shock waves in dusty nonideal gas flow with magnetic field

Abstract This paper deals with the study of propagation of shock waves in 2-D steady supersonic magnetogasdynamics flow of nonideal dusty gas using wavefront analysis method. We derived the transport equation, which determines the condition for the shock formation. Our aim is to analyze the effect of interaction of dust particles with magnetic field in nonideal gas on the evolution of shock formation and to examine how the flow patterns of the disturbance vary with respect to the variations in the physical parameters of the medium. It is found that the presence of magnetic field plays an essential role in the wave propagation phenomena. The nature of the solution with respect to the Mach number is analyzed, and it is examined how the shock formation distance changes with an increase or decrease in the value of Mach number. Also, the combined effect of nonidealness, magnetic field, and dust particles on the shock formation distance is elucidated and examined how the formation of shocks is affected by the increase in the value of corresponding physical parameters.

A new magnetic enhanced chemical mechanical polishing method for quartz glass slender holes

Due to the limitations of tool size, field assisted polishing methods are often employed for polishing the internal surfaces of slender holes with large aspect ratios. However, in existing polishing methods, fields are often applied in isolation, which limits the ability to obtain high surface quality. Furthermore, it is rare for polishing method studies to fully leverage the advantages of multiple fields to create a synergistic effect. Therefore, developing a polishing method that harnesses the synergistic interaction of multiple fields, and revealing the polishing mechanism, is crucial for achieving high-quality internal surfaces of quartz slender holes. To address this problem, a novel magnetic enhanced chemical mechanical polishing method was proposed in this paper and a systematic process study was carried out to analyze the synergistic effects of magnetic and chemical fields. To evaluate the effects of process parameters on material removal and forecast MRR, the material removal process was modeled and validated based on the consistency between experimental and theoretical values. Suitable process parameters are determined through experiments and analysis on magnetic field distribution and process parameters. By conducting EDS mapping and XPS analyses on the reaction product, the enhancement mechanism of magnetic field on material removal in the chemical mechanical polishing process was identified. Under the assistance of a magnetic field, the magnetic abrasive particles encircle the CeO2 particles to fully contact the workpiece surface. The contact force between the polishing tool and the workpiece surface increase. Both of the effects promote the chemical reaction and enable the reaction layer on the surface to be removed in time to obtain higher surface quality. As a result, this method achieves high-efficiency and high-quality polishing, significantly reducing the surface roughness Sa of slender holes from 0.3 μm to 77 nm, with a material removal rate of 141 μm/h.

Advance effect of magnetic field on the rheological properties of manganese zinc ferrite ferrofluid

The rheological characteristics of manganese zinc (Mn-Zn) ferrite magnetic nanofluid synthesized using co-precipitation technique were examined in the absence and presence of magnetic fields. The research formulates required conditions needed for the formation of a gelly-like structure. The impact of magnetic field and temperature on the rheological properties of Mn-Zn ferrite ferrofluid is investigated. When a magnetic field was applied, higher magnetoviscoelasticity and magnetoviscosity were formed. Analysis was also done on other rheological parameters, such as the damping factor, which is crucial for regulating and restricting vibrations in a system. A stiff, gel-like structure is produced when a magnetic field is applied, and the gel-like quality grows as the magnetic field increases; when the magnetic field is removed, the gel-like and rigidity of the structure is lost. At low temperatures, the liquid phase is dominated by solid-like particles, whereas at high temperatures, the liquid-like structure is dominant. This study reveals the conditions required for the creation of high viscous effect and the viscoelastic behavior induced by the field offers important insights for optimizing the Mn-Zn ferrite ferrofluid for a range of applications. Other criterial for gel-like structure formation such as low torque and deflection angle of the ferrofluid were also established.

Effect of Magnetic Field on Frozen Food Quality Characteristics

Effect of Magnetic Field on Frozen Food Quality Characteristics