Homogeneous Static Magnetic Field Research Articles

The model for study of influence Of magnetic fields on biological objects (within the Russian maglev project)

Aim: methodological aspects of the study influenced static magnetic fields (SMF) used in the technology "Russian Maglev" on the organisms are improved.
 Materials and methods: organotypic culture of animal tissue fragments was studied under the influence of an experimental setup generating a homogeneous SMF with characteristics similar the "Russian Maglev".
 Results: area index (AI) for liver, heart, prostate, renal tissue of explants in the control and under the action of SMF did not differ. SMF significantly reduces AI of explants the immune tissue of the spleen and the cerebral cortex.
 Conclusions: 1. the influence of SMF has a negative impact on the proliferative activity in organotypic culture of the cerebral cortex and spleen; 2. the biological model for examination of influence SMF on organisms intended for approbation of means of physical protection is presented.

Structural Transformation of Bilayer Ferro-foams Caused by Homogeneous Static Magnetic Field

Structural transformation of honeycomb structure bilayer ferro-foams caused by homogeneous magnetic field is investigated in this paper. Previous researchers have proved that monodisperse bilayer foams with honeycomb structure can transform reversibly by changing foam liquid fraction. However, we have observed that, when applying a homogeneous magnetic field, bilayer foams can also perform this transformation at a constant liquid fraction. This self-organizational behavior of foam structure is believed to be based on energy minimization principle, the magnetic interaction of Ferro-foams Plateau borders change the total energy of the whole system, which trigger the structure transformation process.

Single-photon superradiance in a single-crystal semiconductor film in the saturation mode

Single-photon superradiance was studied at cyclotron resonance in an ideal single-crystal semiconductor p-type film, with a cubic structure placed in a homogeneous static strong magnetic field perpendicular to the film surface. The analysis was performed at a low temperature, at which the density of holes at the Landau level n = 0 was maximum, and at the Landau level n = 1 was zero. The current density in the film was calculated using the Lindblad equation for the density matrix, and the parameters of electromagnetic field radiated by the film in the saturation mode, when the radiated electric field strength was high, were studied. It was shown that the universal loss power per unit area of the film depends only on the fundamental constants c, qe, and me, and on the induction of the magnetic field. The conductivity of the film was calculated.

Theory of the Hall effect in three-dimensional metamaterials

We apply homogenization theory to calculate the effective electric conductivity and Hall coefficient tensor of passive three-dimensionally periodic metamaterials subject to a weak external static homogeneous magnetic field. We not only allow for variations of the conductivity and the Hall coefficient of the constituent material(s) within the metamaterial unit cells, but also for spatial variations of the magnetic permeability. We present four results. First, our findings are consistent with previous numerical calculations for finite-size structures as well as with recent experiments. This provides a sound theoretical justification for describing such metamaterials in terms of effective material parameters. Second, we visualize the cofactor fields appearing in the homogenization integrals. Thereby, we identify those parts of the metamaterial structures which are critical for the observed effective metamaterial parameters, providing a unified view onto various previously introduced single-constituent/multiple-constituent and isotropic/anisotropic architectures, respectively. Third, we suggest a novel three-dimensional non-magnetic metamaterial architecture exhibiting a sign reversal of the effective isotropic Hall coefficient. It is conceptually distinct from the original chainmail-like geometry, for which the sign reversal is based on interlinked rings. Fourth, we discuss two examples for metamaterial architectures comprising magnetic materials: yet another possibility to reverse the sign of the isotropic Hall coefficient and an approach to conceptually break previous bounds for the effective mobility.

Effect of homogeneous static magnetic treatment on the adsorption capacity in maize seeds (Zea mays L.).

In order to analyze the treatment of seeds with homogeneous static magnetic field on the water adsorption process, an experimental-theoretical study of hygroscopic equilibrium in maize seeds (Zea mays L. cv. ICAV305) was carried out. Four treatments with magnetic induction of 80.0, 120.0, 160.0, and 200.0 mT were applied for 10 min, and there was a control group without treatment. The doses were selected because they showed a decrease in mean germination time. Treated seeds were subjected to an environment with a stable temperature of 30.0 °C ± 0.1 °C and atmospheres of different relative humidity (h), using eight salt solutions saturated with water activity between 0.216 and 0.970. Curves were adjusted using the D'Arcy-Watt and modified Oswin models. It was found that the magnetic treatment of seeds affects adsorption, and the 200 mT-10 min one was the most significant in affecting the mechanisms of adsorption of water, and increasing the number of adsorption sites connected to weak binds with D'Arcy-Watt's adjustment. Using the Oswin model for simulation, we verified that the magnetic stimulus affected the enthalpy of adsorption and the mechanism of incorporation of water vapor molecules to the structure of seminal cover. These results show that the magnetic pre-treatment of seeds has an effect on a seed's specific biophysical and physiological processes in the early stages of germination. Bioelectromagnetics. 39:343-351, 2018. © 2018 Wiley Periodicals, Inc.

Homogenous static magnetic field coils dedicated to portable nuclear magnetic resonance for agronomic studies

Abstract. Nuclear magnetic resonance (NMR) experiments are usually carried out at very high and homogenous magnetic fields. However, portable systems have emerged in recent years at low fields, offering many advantages like easier maintenance and open design that permit us to imagine a variety of coil configurations in order to maximize the homogeneity of the static field B0 and the radio-frequency field B1. The wire winding distribution based on space harmonics suppression (SHS) of the cosine current density distribution offers new possibilities of producing homogenous static fields B0. In this work, an extension of the SHS method, allowing homogeneity enhancement and flexibility of the coil design, is presented. The efficiency of the method is demonstrated through the construction of homogenous magnetic field coils dedicated to a very low magnetic field (8 mT) 1H NMR spectrometer. The performance of these coils in terms of magnetic field intensity and homogeneity as well as self-heating behavior is compliant with in planta experiments for agronomic studies.

The Static Magnetic Field Remotely Boosts the Efficiency of Doxorubicin through Modulating ROS Behaviors

Exposure to magnetic field (MF) can affect cellular metabolism remotely. Cardio-toxic effects of Doxorubicin (DOXO) have limited clinical uses at high dose. MF due to its effect on reactive oxygen species (ROS) lifetime, may provide a suitable choice to boost the efficacy of this drug at low dose. Here, we investigated the potential effects of homogenous static magnetic field (SMF) on DOXO-induced toxicity and proliferation rate of cancer cells. The results indicated that SMF similar to DOXO decreased the cell viability as well as the proliferation rate of MCF-7 and HFF cells. Moreover, combination of 10 mT SMF and 0.1 µM DOXO decreased the viability and proliferation rate of cancer and normal cells in a synergetic manner. In spite of high a GSH level in cancer cell, SMF boosts the generation and lifetime of ROS at low dose of DOXO, and overcame to GSH mediated drug resistance. The results also confirmed that SMF exposure decreased 50% iron content of cells, which is attributed to iron homeostasis. In conclusion, these findings suggest that SMF can decrease required dose of chemotherapy drugs such as DOXO and thereby decrease their side effect.

Influence of background gas and external magnetic field on the localization of particles in two dimensional yukawa systems

We investigate the simultaneous effect of a static homogeneous external magnetic field and a background gas medium on the quasi-localization of the dust particles – characterized quantitatively by cage correlation functions – in strongly coupled two-dimensional Yukawa systems. We apply the Langevin dynamics computer simulation method in which the frictional and Lorentz forces are taken into account. Both the presence of the magnetic field and the friction originating from the background gas, when acting alone, increase the caging time. When present simultaneously, however, we find that their effects combine in a non-trivial manner and act against each other within a window of the parameter values. For a fixed magnetic field, the increasing friction was found to first decrease the caging time and then to increase it beyond a certain value of the friction coefficient that depends on the magnetic field strength. A qualitative explanation was given for these observations based on the analysis of the peculiarities of the trajectories of individual particles. undefined undefined Звуковая функция ограничена 200 символами Настройки : История : Обратная связь : Donate Закрыть

The Effect of Inhomogeneous Background Magnetic Field on the Electromagnetic Response to High-Frequency Gravitational Waves

Transverse perturbative photon fluxes (PPFs) generated by an electromagnetic (EM) response system for high-frequency gravitational waves (HFGWs) detection, is a special physical effect related to some properties of HFGWs. Meanwhile, it is also influenced by the background static magnetic field. In this paper, based on the relationship between PPFs and the distribution of a Gaussian Beam with a homogeneous background static magnetic field, we study the distribution of PPFs and the width of positive signal photon fluxes with an inhomogeneous background static magnetic field. Under this condition, the strength of PPFs is enhanced significantly. Furthermore, by adjusting some parameters and an embedded non-coaxial coil in the background magnetic coil, the width of positive-signal photon fluxes would be enlarged greatly.

Simultaneous effect of an external magnetic field and gas‐induced friction on the caging of particles in two‐dimensional Yukawa systems

We investigate the simultaneous effect of a static homogeneous external magnetic field and a background gas medium on the quasi‐localization of the dust particles—characterized quantitatively by cage correlation functions—in strongly coupled two‐dimensional Yukawa systems. We apply the Langevin dynamics computer simulation method in which the frictional and Lorentz forces are taken into account. Both the presence of the magnetic field and the friction originating from the background gas, when acting alone, increase the caging time. When present simultaneously, however, we find that their effects combine in a non‐trivial manner and act against each other within a window of the parameter values.

Heavy quark potential in a static and strong homogeneous magnetic field

We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the effective gluon propagator. As an artifact of strong magnetic field approximation (eB>>T^2 and eB>>m^2), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meager and becomes independent of the temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark (Q) and anti-quark (bar{Q}) is obtained in a hot QCD medium in the presence of a strong magnetic field by correcting both short- and long-range components of the potential in the real-time formalism. It is found that the long-range part of the quarkonium potential is affected much more by magnetic field as compared to the short-range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind Qbar{Q} together. For example, the J/psi is dissociated at eB sim 10 m_pi ^2 and Upsilon is dissociated at eB sim 100 m_pi ^2 whereas its excited states, psi ^prime and Upsilon ^prime are dissociated at smaller magnetic field eB= m_pi ^2, 13 m_pi ^2, respectively.

Linear stability analysis of magnetohydrodynamic duct flows with perfectly conducting walls.

The stability of magnetohydrodynamic flow in a duct with perfectly conducting walls is investigated in the presence of a homogeneous and constant static magnetic field. The temporal growth and spatial distribution of perturbations are obtained by solving iteratively the direct and adjoint governing equations with respect of perturbations, based on nonmodal stability theory. The effect of the applied magnetic field, as well as the aspect ratio of the duct on the stability of the magnetohydrodynamic duct flow is taken into account. The computational results show that, weak jets appear near the sidewalls at a moderate magnetic field and the velocity of the jet increases with the increase of the intensity of the magnetic field. The duct flow is stable at either weak or strong magnetic field, but becomes unstable at moderate intensity magnetic field, and the stability is invariance with the aspect ratio of the duct. The instability of magnetohydrodynamic duct flow is related with the exponential growth of perturbations evolving on the fully developed jets. Transient growth of perturbations is also observed in the computation and the optimal perturbation is found to be in the form of streamwise vortices and localized within the sidewall layers. By contrast, the Hartmann layer perpendicular to the magnetic field is irrelevant to the stability issue of the magnetohydrodynamic duct flow.

Instability of MHD Flow in the Duct with Electrically Perfectly Conducting Walls

The stability problem of conducting fluid flow in a square duct with perfectly conducting walls is investigated. A homogeneous and constant static magnetic field is applied along the vertical direction of the flow. Nonmodal linear stability analysis is performed on this problem for the first time and the effect of the imposed magnetic field is also taken into account. The amplification and distribution of primary optimal perturbations are obtained by solving iteratively the direct and adjoint governing equations with respect of perturbations. Four modes of perturbations with different symmetries in the space are investigated. Computational results show that, the MHD duct flow is stable at either small or large Hartmann number, but unstable at moderate one. The primary optimal perturbations are in the form of streamwise vortices, which are located inside the thin sidewall layers parallel to the magnetic field. The size of the vortices is decreased with the growing of Hartmann number Ha, meanwhile the amplification of the perturbations is reduced due to the magnetic damping effect. The Hartmann layer perpendicular to the magnetic field seems to be irrelevant to the stability of the MHD duct flow. The most unstable perturbation is in the form of Mode I, which having co-rotating vortices at opposite sidewalls and the vortices tend to enhance each other.

High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment.

High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

V-shaped portable NMR sensor with a deep penetration depth and its application in assessing the aging level of turbine oils in power stations

This paper presents a simple design for a nuclear magnetic resonance (NMR) sensor and its application for detecting turbine oil in two power stations. The magnet, which is composed of two identical cuboid permanent magnet blocks and two iron shimming sheets of a special shape, generates a relatively homogeneous static magnetic B0 field (∼ 364 ppm) on a 10 × 10 mm 2 region of interest. In the vertical direction, it produces a constant gradient of ∼15.5 T/m within 5 mm which allows for self-diffusion measurements and 1 dimensional imaging. This NMR sensor can produce a deep penetration depth into the samples with relatively strong and uniform B0 strength. The NMR sensor was specially designed for assessing the aging status of turbine oil in a power station, and a group of turbine oil of different service times was measured. Results demonstrate that an increase in the service time of the turbine oils clearly decreases transverse relaxation time T2. This portable sensor can be used in fields and provide quantitative evaluation parameters of the aging status of turbine oil during periodic inspection.

Homogeneous static magnetic field of different orientation induces biological changes in subacutely exposed mice

It has been shown that static magnetic field (SMF) of moderate intensity produces considerable impact on biological systems. SMF can be homogeneous or inhomogeneous. In many studies, inhomogeneous SMF was employed. Aware that inhomogeneous SMF could result in experimental variability, we investigated the influence of a vertical homogeneous SMF of different orientation. Male Swiss-Webster 9- to 10-week-old mice were subacutely exposed to upward- and downward-oriented SMF of 128mT generated by a cyclotron for 1h/day during a 5-day period. We found that SMF affected various organs and that these effects were, to some degree, dependent on SMF orientation. Both upward- and downward-oriented SMF caused a reduction in the amount of total white blood cells (WBC) and lymphocytes in serum, a decrease of granulocytes in the spleen, kidney inflammation, and an increase in the amount of high-density lipoprotein (HDL). In addition, upward-oriented SMF caused brain edema and increased spleen cellularity. In contrast, downward-oriented SMF induced liver inflammation and a decrease in the amount of serum granulocytes. These effects might represent a specific redistribution of pro-inflammatory cells in blood and among various organs. It appears that homogeneous SMF of 128mT affected specific organs in the body, rather than simultaneously and equally influencing the entire body system.

Static magnetic field can transiently alter the human intracortical inhibitory system

ObjectiveAlthough recent studies have shown the suppressive effects of static magnetic fields (SMFs) on the human primary motor cortex (M1) possibly due to the deformed neural membrane channels, the effect of the clinical MRI scanner bore has not been studied in the same way. MethodsWe tested whether the MRI scanner itself and compact magnet can alter the M1 function using single- and paired-pulse transcranial magnetic stimulation (TMS). ResultsWe found the transient suppression of the corticospinal pathway in both interventions. In addition, the transient enhancement of the short-latency intracortical inhibition (SICI) was observed immediately after compact magnet stimulation. ConclusionsThe present results suggest that not only the inhomogeneous SMFs induced by a compact magnet but also the homogeneous SMF produced by the MRI scanner bore itself can produce the transient cortical functional change. SignificanceStatic magnetic stimulation can modulate the intracortical inhibitory circuit of M1, which might be useful for clinical purposes.

A Miniature Electron Spin Resonance Probehead for Transcutaneous Oxygen Monitoring

Oxygen concentration in the skin is an important clinical indicator for monitoring pathological conditions such as chronic wounds, skin cancer, and peripheral vascular disease. Currently, the only clinically approved method for acquiring these oxygen levels is based on electrochemical measurements that employ Clarke-type electrodes attached to the skin. This technique has many drawbacks and limitations, making it unattractive for standard medical practice and care. Electron spin resonance (ESR), which can obtain the oxygen concentration through measurements of the spin–spin relaxation time (T 2) of paramagnetic species interacting with molecular oxygen, provides a possible alternative. However, a traditional ESR setup requires a large homogenous static magnetic field source with limited gap between the poles and complicated equipment, making it unattractive for clinical use. Here, we present a new design for a miniature ESR probehead, which is comprised of a specially designed permanent magnet and a small microwave resonator. The small size of the probehead (36 mm diameter cylinder with a height of 24 mm) enables transcutaneous measurements from virtually any part of the skin. Compared to the electrochemical method, this ESR-based approach may provide faster and more accurate readings of oxygen concentration in the skin, making it highly attractive for future clinical use.

Pharmacological analysis of response latency in the hot plate test following whole-body static magnetic field-exposure in the snail Helix pomatia

Purpose: To study the effect of single, 30-min long, whole-body, homogeneous static magnetic field (SMF)-exposure of magnetic induction 147±3 mT on the response latency of the snail Helix pomatia.Materials and methods: The response was investigated using the hot plate test.Results: The effect caused by exposure to SMF was compared to sham-exposure and resulted in significant differences (up to 47.1%, p < 0.001). The response latency depended on the day-night cycle; response latency was higher by 51.2% (p < 0.001) during the night. This trend also held for SMF- exposure (28.6%, p < 0.001). Serotonin alone increased response latency (55.7%, p < 0.001), whereas serotonin antagonist tryptamine decreased it (− 97.8%, p < 0.001). Using naloxone, response latency decreased (− 52.5%, p < 0.001); however both SMF-exposure and serotonin in combination with naloxone rose it back to above the control level (116.9%, p < 0.001 or 150.2%, p < 0.001, respectively).Conclusions: This study provides evidence that SMF-exposure mediates peripheral thermal nociceptive threshold by affecting the serotonerg as well as the opioiderg system.

Effect of polarization and focusing on laser pulse driven auto-resonant particle acceleration

The effect of laser polarization and focusing is theoretically studied on the final energy gain of a particle in the Auto-resonant acceleration scheme using a finite duration laser pulse with Gaussian shaped temporal envelope. The exact expressions for dynamical variables viz. position, momentum, and energy are obtained by analytically solving the relativistic equation of motion describing particle dynamics in the combined field of an elliptically polarized finite duration pulse and homogeneous static axial magnetic field. From the solutions, it is shown that for a given set of laser parameters viz. intensity and pulse length along with static magnetic field, the energy gain by a positively charged particle is maximum for a right circularly polarized laser pulse. Further, a new scheme is proposed for particle acceleration by subjecting it to the combined field of a focused finite duration laser pulse and static axial magnetic field. In this scheme, the particle is initially accelerated by the focused laser field, which drives the non-resonant particle to second stage of acceleration by cyclotron Auto-resonance. The new scheme is found to be efficient over two individual schemes, i.e., auto-resonant acceleration and direct acceleration by focused laser field, as significant particle acceleration can be achieved at one order lesser values of static axial magnetic field and laser intensity.