Presence Of Static Magnetic Field Research Articles

Thermoluminescence dosimetry (TLD) in a 3 T magnetic resonance imaging (MRI) environment: implications for personnel exposure monitoring.

Thermoluminescent dosimeters (TLDs) serve as compact and user-friendly tools for various applications, including personal radiation dosimetry and radiation therapy. This study explores the potential of utilizing TLD-100 personal dosimetry, conventionally applied in PET/CT (positron emission tomography/computed tomography) settings, in the PET/MRI (magnetic resonance imaging) environment. The integration of MRI into conventional radiotherapy and PET systems necessitates ionizing radiation dosimetry in the presence of static magnetic fields. In this study, TLD-100 dosimeters were exposed on the surface of a water-filled cylindrical phantom containing PET-radioisotope and positioned on the patient table of a 3 T PET/MRI, where the magnetic field strength is around 0.2 T, aiming to replicate real-world scenarios experienced by personnel in PET/MRI environments. . Results indicate that the modified MR-safe TLD-100 personal dosimeters exhibit no significant impact from the static magnetic field of the 3 T PET/MRI, supporting their suitability for personal dosimetry in PET/MRI settings. This study addresses a notable gap in existing literature on the effect of MRI static magnetic field on TLDs.

Magnetic-field-induced splitting of Rydberg Electromagnetically Induced Transparency and Autler-Townes spectra in 87Rb vapor cell.

We theoretically and experimentally investigate the Rydberg electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting of 87Rb vapor under the combined influence of a magnetic field and a microwave field. In the presence of static magnetic field, the effect of the microwave field leads to the dressing and splitting of each mF state, resulting in multiple spectral peaks in the EIT-AT spectrum. A simplified analytical formula was developed to explain the EIT-AT spectrum in a static magnetic field, and the theoretical calculations agree qualitatively with experimental results. The Rydberg atom microwave electric field sensor performance was enhanced by making use of the splitting interval between the two maximum absolute mF states separated by the static magnetic field, which was attributed to the stronger Clebsch-Gordon coefficients between the extreme mF states and the frequency detuning of the microwave electric field under the static magnetic field. The traceable measurement limit of weak electric field by EIT-AT splitting method was extended by an order of magnitude, which is promising for precise microwave electric field measurement.

Probing Into the Drying Pattern Dynamics of a Ferrofluid Droplet Under the Actuation of Magnetic Field

Evaporation of liquids, especially colloids, is a subject of research interest since decades. Evaporation patterns of colloidal particles can determine key factors about the liquid properties and the underlying physics. Particle deposition, self-assembly, and inkjet printing are various applications, where the control of droplet evaporation and its patterns can be useful. Here, kerosene-based ferrofluid droplets were allowed to evaporate in the presence of static magnetic field. Earlier, the evaporation pattern of the same fluid in ambient conditions was reported, where ring pattern with central accumulation was observed. This was attributed to thermal Marangoni flow. In this case, magnetic field helps in circumventing this pattern, and directional dependence on magnetic field in the final patterns was also observed. Magnetic field parallel to the substrate created chain structures in the direction of the field, whereas magnetic field perpendicular to the substrate resulted in completely uniform pattern. For higher volume fraction of the chosen samples, the influence of external magnetic field was seen earlier than the samples of lower volume fraction. Effect of substrate wettability was observed under similar conditions for glass substrate and Polydimethylsiloxane (PDMS) substrate. These experimental results are compared/supported by the available existing theoretical results/theories. The inferences obtained from this analysis are expected to be useful in the optimization of particle deposition of magnetic colloids, typically of demanding significance in fields, such as nanochromatography, lithography, surface engineering, self-assembly, inkjet printing, and so on.

Origin of static magnetic field induced quality improvement in sea bass (Lateolabrax japonicus) during cold storage: Microbial growth inhibition and protein structure stabilization.

To explore the potential application of static magnetic field (SMF) treatment in marine fish preservation, the sea bass (Lateolabrax japonicus) was exposed to SMF (5 mT) and its quality changes during cold storage were evaluated by total viable counts, water holding capacity, pH, color, and textural properties. Characteristics of the protein in the presence of SMF were investigated by measuring total sulfhydryl (SH) content, Ca2+-ATPase activity, secondary structure, and muscle microstructure. SMF treatment exhibited positive effects on fish quality, showing favorable performance on the most quality indicators, especially a significant reduction in the Microbial Counts. Furthermore, higher total SH content and Ca2+-ATPase activity were observed in SMF-treated samples, demonstrating that the oxidation and denaturation of myofibrillar protein (MP) were delayed due to SMF treatment. The transformation of α-helix to random coil was prevented in SMF-treated samples, indicating that the secondary structure of MP was stabilized by SMF treatment. The above changes in protein structures were accompanied by changes in muscle microstructure. More intact and compact structures were observed in SMF-treated samples, characterized by well-defined boundaries between myofibers. Therefore, our findings suggest that under the conditions of this article, SMF treatment could maintain the quality of fish mainly by inhibiting the growth of microorganisms and enhancing the stability of protein structures, and could be a promising auxiliary technology for preservation of aquatic products.

Comment on the paper “Optimization of heat transfer properties on ferrofluid flow over a stretching sheet in the presence of static magnetic field, Anupam Bhandari, Akmal Husain, Journal of Thermal Analysis and Calorimetry (2021) 144:1253–1270”

Comment on the paper “Optimization of heat transfer properties on ferrofluid flow over a stretching sheet in the presence of static magnetic field, Anupam Bhandari, Akmal Husain, Journal of Thermal Analysis and Calorimetry (2021) 144:1253–1270”

Instabilities in magnetized inhomogeneous dusty plasmas with the effect of recombination

An analytical formalism to understand the impact of various parameters on evolving instabilities in inhomogeneous collisional dusty plasmas is presented here under the effect of recombination. The basic fluid dynamics for electrons and singly charged cold ions is carried out including recombination and collision at constant rate at the surface of dust particles. Dust particles are considered to be static with unperturbed density. Normal mode analysis method has been used along with linear approximation to get perturbed densities (n i1, n e1) which are used along with quasi-neutrality condition to get perturbed potential using Poisson’s equation to obtain dispersion relation. While other authors have detected instabilities in unmagnetized plasmas, here this method has been successfully realized in presence of static magnetic field at various propagation angle and allowed the straightforward calculation of growth rates of observed instability. An extensive study of the unstable modes has been done which are well discriminated and plotted with respect to different plasma parameters like dust charge, dust density, propagation angle, magnetic field, electrostatic potential along with plasma oscillation wavelength to Debye wavelength ratio. We have observed in the said model that the presence of dust particles and propagation angle of applied magnetic field are affecting significantly the growth rate of instability as compared to magnetic field and recombination.

Experimental study on carbon dioxide hydrate formation in the presence of static magnetic field

The formation kinetic parameters, phase equilibrium and dissociation enthalpy of carbon dioxide hydrate in the presence of static magnetic field were investigated in this work. The experiments were carried out in pure water and (0.029, 0.056 and 0.110, mass fraction) sodium chloride (NaCl) aqueous solution with a magnetic field of 0.39 T. The experimental results showed that the induction time of carbon dioxide hydrate nucleation was shortened, the consumption amount and rate of carbon dioxide were significantly increased with the magnetic field. This phenomenon is mainly attributed to the fact that the magnetic effect decreases the contact angle between water and solid surface to reduce the critical size and critical free energy of hydrate nucleation. Moreover, the phase equilibrium of carbon dioxide hydrate in both pure water and NaCl aqueous solution shifted to lower pressure or higher temperature with the magnetic field, and the equilibrium temperature in pure water decreased by 3.0 K, which is due to the change of the hydrogen bond in small clusters and ions mobility by magnetic effect. In addition, the dissociation enthalpies of carbon dioxide hydrate in pure water and (0.029, 0.056 and 0.110) NaCl solution calculated by Clausius-Clapeyron equation were 91.5, 91.4, 62.8 and 52.0 kJ·mol−1, respectively, in the magnetic field, which is related to the movements of ions caused by magnetic effect and heat absorption.

Superparamagnetic Iron Oxide Nanoparticles and Static Magnetic Field Regulate Neural Stem Cell Proliferation.

Neural stem cells (NSCs) transplantation is a promising approach for the treatment of various neurodegenerative diseases. Superparamagnetic iron oxide nanoparticles (SPIOs) are reported to modulate stem cell behaviors and are used for medical imaging. However, the detailed effects of SPIOs under the presence of static magnetic field (SMF) on NSCs are not well elucidated. In this study, it was found that SPIOs could enter the cells within 24 h, while they were mainly distributed in the lysosomes. SPIO exhibited good adhesion and excellent biocompatibility at concentrations below 500 μg/ml. In addition, SPIOs were able to promote NSC proliferation in the absence of SMF. In contrast, the high intensity of SMF (145 ± 10 mT) inhibited the expansion ability of NSCs. Our results demonstrate that SPIOs with SMF could promote NSC proliferation, which could have profound significance for tissue engineering and regenerative medicine for SPIO applications.

Magnetic field induced multichannel tunable filter properties of photonic band gap materials

we have explored the tunable multichannel characteristics of one-dimensional (1D) plasma photonic structure in presence of static magnetic field applied externally parallel and anti-parallel to the direction of propagation under normal incidence. We have theoretically examined the transmission characteristics of the binary photonic design consisting of alternate layers of CaF2 and magnetic cold plasma layers by means of transfer matrix method (TMM) which is amongst the one of the popular techniques for simulating 1D multilayer periodic structures based on MATLAB. The proposed structure possess N-1 number of distinct transmission peaks, each of unit transmission called as transmission channels in transmission spectra for given the number of periods N > 1. In this study N varies from 2 to 6 in steps of 1 to get 1 to 5 transmission channels respectively. Further we have also investigated how these transmission channels can be repositioned inside PBG by applying the static magnetic field (B) externally under right hand polarization (RHP) and lift hand polarization (LHP) configurations for given N at B = 0T, 0.02T, 0.04T and 0.06T. The reason behind the existence of these transmission channels is due to the superposition of evanescent and propagating waves inside plasma and dielectric layers respectively. The existence of these transmission channels inside PBG is different from the transmission bands which are formed due to the interference of forward and backward propagating waves. Besides this the tuning sense of the transmission channels at fixed B applied parallel or anti parallel to direction of periodicity, by changing the angle of incidence corresponding to TE and TM polarization case has also been examined to get some more useful and interesting tunable multichannel characteristics of the current design which cannot be obtained in conventional PPCs.

Investigation of static magnetic field effect on horseradish peroxidase enzyme activity and stability in enzymatic oxidation process

The activity of Horseradish Peroxidase (HRP) Enzyme exposed to a static magnetic field (SMF) during the oxidation reaction of pyrogallol (PGL) and the epigallocatechin gallate (EPCG) flavonoid was recorded at different times. As the data showed, the enzyme activity increased by 77.17% with increasing incubation time up to 30 min. The kinetic parameters KM and Vmax for PGL sample incubated in SMF for 30 min were 5.641 × 10−3 mM, 4.424 × 10−2 mmol/min, respectively, and for EPCG sample with the same condition were 8.65 × 10−4 mM, 2.37 × 10−3 mmol/min, respectively. Exposure of HRP enzyme to SMF changed the optimum pH from 7.0 to 6.0 in 10 min, but did not create any change in the optimum temperature of the enzyme. After 120 h, the residual activity of normal enzyme was 17% higher than that of the incubated enzyme. The structural changes of the control and HRP enzyme incubated in SMF were investigated by relative viscosity, fluorescence and CD, UV–Vis spectrophotometry. The structural changes in the presence of SMF were found to cause changes in the enzyme activity. In fact, changes in the amount of hydrogen bonds between enzymes and solvents can be a reason for this behavior from a molecular point of view. Using a static magnetic field can provide a new approach to control and direct enzyme-based biological processes.

Dipole excitation of collective modes in viscous two-dimensional electron systems

We describe the structure of the time-harmonic electromagnetic field of a vertical Hertzian electric dipole source radiating over an infinite, translation invariant two-dimensional electron system. Our model for the electron flow takes into account the effects of shear and Hall viscosities as well as an external static magnetic field perpendicular to the sheet. We identify two wave modes, namely, a surface plasmon and a diffusive mode. In the presence of an external static magnetic field, the diffusive mode combines the features of both the conventional and Hall diffusion and may exhibit a negative group velocity. In our analysis, we solve exactly a boundary value problem for the time-harmonic Maxwell equations coupled with linearized hydrodynamic equations for the flat, two-dimensional material. By numerically evaluating the integrals for the electromagnetic field on the sheet, we find that the plasmon contribution dominates in the intermediate-field region of the dipole source. In contrast, the amplitude of the diffusive mode reaches its maximum value in the near-field region, and quickly decays with the distance from the source. We demonstrate that the diffusive mode can be distinguished from the plasmon in the presence of the static magnetic field, when the highly oscillatory plasmon is gapped and tends to disappear.

Circularly polarized terahertz pulse generation in a plasma channel created by a uv high-intense laser pulse in the presence of a static magnetic field.

This paper is devoted to the problem of obtaining high-intense circularly polarized terahertz radiation in a nonequilibrium xenon plasma channel in the presence of an external static magnetic field. The physical mechanism is based on the well-known cyclotron resonance effect which enables to provide effective plasma-electromagnetic wave interaction that can increase the gain in plasma proposed earlier by the authors. According to the suggested scheme, a static magnetic field is imposed on a gas target along the propagation direction of a femtosecond ultraviolet laser driver. Numerical simulations demonstrate that, by varying a magnetic field, one can control the range of amplified frequencies in plasmas at atmospheric and lower pressures. Moreover, a pressure decrease in the nonequilibrium rare gas plasma channel allows one to obtain a larger value of the gain factor. Thus, controlling the central frequency and bandwidth of the amplified terahertz signals leads to producing both ultrashort and rather long high-intense pulses at the output of nonequilibrium plasma channel.

Tunable THz Pulses Generation in Non-Equilibrium Magnetized Plasma: The Role of Plasma Kinetics

In this paper the theoretical model to consider the influence of kinetic properties of nonequilibrium two-color plasma during the THz pulses generation in the presence of static magnetic field is developed. It is shown that applying a static magnetic field on a gas along the direction of propagation of an ionizing two-color laser pulse allows one to produce two-frequency emissions in THz range with tunable central frequency and bandwidth, which are strongly dependent on electron velocity distribution function (EVDF) formed in the plasma as well as relations between collisional, plasma and cyclotron frequencies.

Co-enhanced activated sludge system by static magnetic field and two halotolerant yeasts for azo dye treatment.

The effect of static magnetic field (SMF) on azo dye Acid Red B (ARB) decolorization by the co-culture of activated sludge (AS) and two halotolerant yeasts Candida tropicalis A1 and Pichia occidentalis A2 was investigated. Microbial community structure of the co-cultures before and after treatment with SMFs of different intensity was analyzed through high-throughput sequencing and quantitative real-time polymerase chain reaction. The results showed that ARB decolorization efficiency by the defined co-culture was 1.25-fold to 1.51-fold elevated by 24.6-305.0mT SMF. The best ARB decolorization and chemical oxygen demand (COD) removal performances by the co-culture were both achieved with 95.0mT SMF. By contrast, biomass multiplication and sedimentation property of AS systems were not significantly influenced by SMF. Higher activities of intracellular key enzymes were determined (with 95.0mT SMF) as responsible for better decolorization and COD removal performances. Bacteria belonging to Prolixibacter, Corynebacterium, Pelagibacterium, Demequina, and Sphingobacterium which might be responsible for azo dye decolorization and aromatic compounds biodegradation were significantly enriched only in presence of SMF. Fungal genera Candida and Pichia were also significantly enriched by 41.4-305.0mT SMF, which might be responsible for higher treatment efficiency. PRACTITIONER POINTS: Dye degradation was enhanced by combination of static magnetic field and yeasts. Improvement of enzyme activity was responsible for better treatment performance. Putative azo-degrading-related bacteria and fungi were selectively enriched. High relative abundance of Candida and Pichia ensured high decolorization effects. Potentially effective improvement of bioprocesses for treating hypersaline wastewater.

Improving Azo Dye Decolorization Performance and Halotolerance of Pichia occidentalis A2 by Static Magnetic Field and Possible Mechanisms Through Comparative Transcriptome Analysis.

A halotolerant yeast, Pichia occidentalis A2, was recently isolated that can decolorize various azo dyes. The azo dye decolorization performance of this strain was characterized, including the degradation pathway and detoxification effects of this yeast. Additionally, the effect of static magnetic field (SMF) on this decolorization process was investigated. Activities of key enzymes were analyzed to estimate the change of metabolic activity. Furthermore, possible mechanisms were analyzed through detecting differentially expressed genes between yeast A2 in the absence and presence of SMF. The results indicated that yeast A2 displayed the optimal decolorization performance when the concentrations (in g/L) of glucose, (NH4)2SO4, yeast extract, and NaCl were 4.0, 1.0, 0.1, and ≤30.0, respectively. Meanwhile, the optimal rotation speed, temperature, and pH were 160 rpm, 30°C, and 5.0, respectively. Acid Red B was decolorized and detoxified by yeast A2 through successive steps, including cleavage of the naphthalene–amidine bond, reductive deamination, oxidative deamination/desulfurization, open-loop of hydroxy-substituted naphthalene, and tricarboxylic acid cycle. The dye decolorization efficiency and halotolerance of yeast A2 were enhanced by 206.3 mT SMF. The activities of manganese peroxidase, and laccase were elevated 1.37- and 1.16-fold by 206.3 mT SMF, but lignin peroxidase activity showed little change. It was suggested from the transcriptome sequence that the enhanced halotolerance might be related to the upregulated genes encoding the enzymes or functional proteins related to intracellular synthesis and accumulation of glycerol.

Magnetic Field Assisted Electron Acceleration Due To Inverse Free Electron Laser

Electron acceleration by an Inverse Free Electron Laser (IFEL) pulse in the presence of static magnetic field has been studied. With high intensity laser and plasma interaction, plasma wakefield can be excited which can be further utilized to accelerate injected electrons. Highly energetic laser interacting with plasma excites a wakefield in which injected relativistic electrons are trapped. The presence of static magnetic field provides the additional resonance to the trapped electrons, and the energy of laser is transferred to electrons effectively thereby, resulting in highly energetic electrons of higher energy gain.

Optimization of heat transfer properties on ferrofluid flow over a stretching sheet in the presence of static magnetic field

The main emphasis of the present research is to investigate the composite effects of magnetization force and rotational viscosity on two-dimensional ferrohydrodynamic non-conducting nanofluid flow over a stretching sheet under the influence of the stationary magnetic field. Microrotation of magnetic fluid and rotation of nanoparticles are also considered. Shliomis model is used in the problem formulation, and then the similarity transformation is applied to transform partial differential equations into a set of nonlinear-coupled ordinary differential equations in dimensionless form. Transformed nonlinear-coupled differential equations are solved through the finite element method using COMSOL Multiphysics under the mathematical modeling. Results for velocity distribution, temperature distribution, concentration distribution and angular velocity distribution are obtained after considering the effects of Maxwell parameter, ferromagnetic interaction number, thermal Grashof number, solutal Grashof number, Brownian motion parameter, thermophoresis number, chemical reaction parameter, radiation absorption coefficient, heat generation/absorption parameter, Prandtl number and Schmidt number in the flow. It has been observed that magnetic energy transforms into kinetic energy, thermal boundary layer and concentration boundary layer in the presence of considered physical parameters.

Design of TMS coils with reduced Lorentz forces: application to concurrent TMS-fMRI

Objective. Interleaving TMS (transcranial magnetic stimulation) with fMRI (functional Magnetic Resonance Imaging) is a promising technique to study functional connectivity in the human brain, but its development is being restricted by technical limitations, such as that due to the interaction of the TMS current pulses with the magnetic fields of an MRI scanner. In this work, a TMS coil design method capable of controlling Lorentz forces experienced by the coil in the presence of static magnetic fields is presented. Approach. The suggested approach is based on an existing inverse boundary element method (IBEM) for TMS coil design, in which new electromagnetic computational models of the Lorentz forces have been included to be controlled in the design process. Main results. To demonstrate the validity of this technique, it has been used for the design and simulation of TMS coils wound on rectangular flat, spherical and hemispherical surfaces with improved mechanical stability. The obtained results confirm that TMS coils with reduced Lorentz forces inside the static main field of an MRI scanner can be produced, which is achieved to the detriment of other coil performance parameters. Significance. The proposed approach provides an efficient tool to design TMS stimulators of a wide range of coil geometries with improved mechanical stability, which can be extremely useful to overcome current limitations for interleaved TMS-fMRI.

Investigation of solid/liquid interface evolution in the solidification process of liquid metal in an annulus crucible at the presence of static magnetic field: numerical study

This paper studies the effect of constant magnetic field on solidification of a conductive liquid that filled a vertical three-dimensional annulus-shaped crucible. The computational domain of the proposed geometry is a vertical annulus cavity; the inner and outer sides of the mentioned cavity have constant temperature, but top and bottom sides have been thermally insulated. The governing equations have been solved numerically using finite volume method, so obtained results illustrated acceptable conformity with available reported experimental and numerical data. The investigation has been carried out for various vital parameters, such as Hartmann and Rayleigh numbers. The magnetic field effect on the melted flow field and interface of solid/liquid form and position has been discussed with more details. The numerical results have shown a strong relation between interface shape, Rayleigh number and magnetic field strength. Then, the applied magnetic field leads to vanishing axisymmetric condition of solid/liquid interface. Finally, it has been conducted that strongest stabilization of the flow field and solid/liquid interface occurs at the x–z plane. The proposed predictions are very helpful in developing methods to improve solidification and casting systems under magnetic field effects.

Mesoporous superparamagnetic hydroxyapatite nanocomposite: A multifunctional platform for synergistic targeted chemo-magnetotherapy

In the present study, the aim was to develop a magneto-responsive nanocomposite for application in drug delivery by the integration of magnetic nanoparticles into an inorganic architecture, hydroxyapatite. The magnetic mesoporous hydroxyapatite nanocomposites, MMHAPs, were synthesized using a template-free method and fully characterized by XRD, FT-IR, TEM, FE-SEM, VSM, ICP, BET, and UV–Vis spectroscopy. MMHAPs exhibited a rod-like shape with a structure of large mesopores and high surface area. A sample of the nanocomposites with well-defined properties, MMHAP(2), was selected as a carrier for delivery of chemotherapy drug, doxorubicin (Dox). Then, it was coated with polyethylene glycol (P) and folic acid (F), providing aqueous stability and tumor targeting, respectively. The evaluation of drug release profile revealed that the release of drug occurs in a time-staggered manner under low pH conditions, which simulate the internal condition of lysosome. More important, a significant drug release was observed under a static magnetic field (SMF), displaying a magnetically triggered release. According to the toxicity assessment, MMHAP(2) did not show any noticeable toxic effect against the tumor cells (Saos-2) and normal cells (HEK-293) up to 100 μg ml−1 in the presence or absence of SMF. In contrast, the drug-loaded nanocomposite, F.P.D@MMHAP(2), possesses high antitumor efficacy particularly in the presence of SMF. Moreover, it was found that the cellular internalization of F.P.D@MMHAP(2) could be increased by SMF, providing therapeutic efficiency enhancement. The high cytotoxic effect of F.P.D@MMHAP(2) with the help of SMF caused apoptosis in the tumor cells, which was preceded by a disturbance in the intracellular redox state and then caspase activation. Based on the data obtained, F.P.D@MMHAP(2) is a pH- and magneto-responsive platform opening up a new perspective in terms of its exploitation in cancer therapy.