Magnetic Fields Of Different Intensities Research Articles

Effects of magnetic field on cd subcellular distribution and chemical speciation in Noccaea caerulescens

Implementing an external magnetic field of suitable strength has been reported to increase Cd uptake by Noccaea caerulescence. However, only a few mechanisms promoting this efficiency have been reported. A series of culture experiments was conducted to explore how Cd subcellular distribution and speciation vary within the tissue of N. caerulescens when subjected to external magnetic fields of different intensities. Without a magnetic field, over 80% of the Cd was deposited in the cell wall and cytoplasm, indicating that cell wall retention and cytoplasm isolation are significant mechanisms for the detoxification of Cd. An external magnetic field (120 mT) increased the Cd concentrations deposited in the cytoplasm and water-soluble inorganic Cd in the roots, increasing the cell wall-bound Cd and undissolved Cd phosphate in the shoots. Meanwhile, the magnetic field increased carbonic anhydrase activity in plant shoots, except at 400 mT. These results indicated that an external field can elevate the Cd decontamination capacity of N. caerulescens by changing the subcellular compartmentalization and speciation of Cd in different tissues.

Modeling and optimisation of magnetic field assisted electrochemical spark drilling using hybrid technique

ABSTRACT The present paper focuses on the application of a hybrid methodology for multi-objective optimisation (MOO) of an in-house deigned and fabricated magnetic field-assisted electrochemical spark drilling (MF-ECSD) process where an electromagnetic unit is added in the setup to create magnetic field of different intensities. The process combines Taguchi methodology (TM) with response surface methodology (RSM) for modelling and grey relational analysis (GRA) with principal component analysis (PCA) methodology for MOO. TM is utilised as the core values in RSM to create the second-order response model, and it is used to find the optimum level of input parameters, namely, voltage (V), electrolyte concentration (EC), tool rotational speed (TRS) and magnetic field intensity (MFI). Material removal rate (MRR), machining depth (MD) and overcut (OC) are the responses. PCA is used to calculate the weight associated with each quality feature.

Numerical renormalization group study of the Loschmidt echo in Kondo systems

We study the dynamical properties of the one-channel and two-channel spin-1/2 Kondo models after quenching in Hamiltonian variables. Eigen spectrum of the initial and final Hamiltonians is calculated by using the numerical renormalization group method implemented within the matrix product states formalism. We consider multiple quench protocols in the considered Kondo systems, also in the presence of external magnetic field of different intensities. The main emphasis is put on the analysis of the behavior of the Loschmidt echo L(t), which measures the ability of the system’s revival to its initial state after a quench. We show that the decay of the Loschmidt echo strongly depends on the type of quench and the ground state of the system. For the one-channel Kondo model, we show that L(t) decays as, L(t)sim (tcdot T_K)^{-1.4}, where T_K is the Kondo temperature, while for the two-channel Kondo model, we demonstrate that the decay is slower and given by L(t)sim (tcdot T_K)^{-0.7}. In addition, we also determine the dynamical behavior of the impurity’s magnetization, which sheds light on identification of the relevant time scales in the system’s dynamics.

Hydrodynamics and Warmth Trade in Cycles of Cooling of an Attractive Plate in an Attractive Fluid in the Attractive Field

The effect of the magnetic field on heat transfer processes of a magnetized steel plate cooled in a magnetic fluid is experimentally studied. Thermocouples were installed at six points on the surface of the plate along its length. The plots of temperature versus time are obtained in the absence of a magnetic field and in magnetic fields of different intensity. It is found that the intensity of heat exchange depends to a large extent on the magnitude of the magnetic field and on the location of points on the surface of the plate. In a magnetic field, cooling of the central part of the plate occurs with the same intensity as in the absence of a magnetic field and with a lower intensity in comparison with other points on the surface of the plate. Near the plate ends, the cooling rate of the surface is much greater in the magnetic field than in the absence of it. With increasing magnetic field strength, the cooling rate of points in the central part of the plate decreases and is less than in the absence of a magnetic field. The dependence of heat transfer on the magnitude of the magnetic field is explained by the distribution of the magnetic forces acting on the liquid surrounding the plate and the nature of the vapor-air cavities formed near its surface. Experiments on simulation of formation and the shape of vapor-air cavities in a liquid surrounding a magnetizing plate are described.

Effects Induced by a Weak Static Magnetic Field of Different Intensities on HT-1080 Fibrosarcoma Cells.

In this study, we investigated the effects of weak static magnetic fields (SMFs) on HT-1080 human fibrosarcoma cells. Exposures to SMFs for four consecutive days were varied from 0.5to 600 µT for treated units, while exposures to control units were held at 45 µT. Growth rates were measured by comparing cell counts, whereas membrane potentials, mitochondrial calcium, mitochondrial superoxide (O2 - ), nitric oxide (NO), hydrogen peroxide (H2 O2 ), intercellular pH, and oxidative stress were measured by using fluorescent dyes. The relative cell growth rates vary with the angle of the SMFs. Increases in the magnitude of the SMFs increased concentrations of mitochondrial calcium and membrane potential and decreased intracellular pH. H2 O2 , an important reactive oxygen species (ROS), increases at 100and 200 µT, decreases at 300and 400 µT and increases again at 500and 600 µT. Overall, oxidative stress increases slightly with increasing SMFs, while superoxide and NO concentrations decrease. These results indicate that weak SMFs can accelerate and inhibit cell growth rates and induce alterations in ROS. Changes in ROS and oxidative stress are important for various cell functions. Calcium influx into mitochondria was one of the initial steps into the corresponding changes. Bioelectromagnetics. 2021. © 2021 Bioelectromagnetics Society.

Refractive-index-matched coupling generated by magnetic fluid around cladding removed multimode optical fiber

Abstract For the cladding removed multimode fiber, when the refractive index of the external solution is close to the fiber core, it will cause refractive-index-matched coupling effect. In this work, the appearance of two index-matched points was observed. One of the index-matched point located at short wavelength, which had not been reported previously. Then, magnetic fluid was used as the external solution around the fiber core. As magnetic fields of different intensities were applied, the refractive-index-matched coupling effect occurred, which was different from that happening within isotropic solution. The observed phenomenon was mainly due to the anisotropy of the magnetic fluid under magnetic field. Based on the establishment of theoretical model and formulation of empirical equation, numerical simulations were also employed to further investigate the refractive-index-matched coupling within the anisotropic solution.

The Effect of Temperature on the Viscosity of Cobalt Ferrite Nanofluids

The temperature dependence of viscosity is an essential property of the magnetic fluids applied for heat transfer systems. This property was considered in our work for Cobalt ferrite nanofluids - one of the most explored magnetic materials recently by their improved magnetic characteristics. Cobalt ferrite nanoparticles (CFNPs) were prepared by the co-precipitation method. The characterization of the synthesized particles was analyzed by various techniques such as X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and thermal gravimetric analysis. The effect of temperature on the viscosity of Cobalt ferrite nanofluids was investigated. Experiments were carried out in the range of particle concentration from 0.5 to 7 % without and with a magnetic field application. The dynamic viscosities of these nanofluids were measured as the shear rate and temperature dependence under the magnetic field of different intensities, using a standard rotating rheometer. The cobalt ferrite fluids exhibit a yield shear-thinning behavior at all the temperatures from 25 to 55 oC. The experimental results show that the viscosity decreases when the temperature is increased. This variation is exponentially and dependent on the shear rate. The temperature-dependent viscosity is not influenced significantly by either particle concentration or magnetic field. From the obtained results, the Arrhenius equation for the viscosity-temperature relationship is applied.

Critical current performance of Bi-2223 HTS tape in temperature range above liquid nitrogen vaporization temperature

<p indent=0mm>(Bi, Pb)₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) high temperature superconducting (HTS) tape is one of the high temperature superconducting wires for commercial applications recently. Its superconducting critical transition temperature is <sc>105–110 K,</sc> which is higher than that of another commercially coated HTS REBa₂Cu₃O₇ conductor tape <sc>(90–93 K).</sc> The Bi-2223 tape has a wide range of superconducting temperatures above the vaporization temperature of liquid nitrogen <sc>(77 K).</sc> The critical currents of two Bi-2223 tape specimens were systematically calculated, and the findings evaluated to understand the superconductive current-carrying characteristics of Bi-2223 tape in the temperature range above <sc>77 K.</sc> To research their effects on the critical current of the specimens in this temperature range, we applied magnetic fields of different intensities and angles to the specimens. The results of the measurement are recorded in this paper in the temperature range of <sc>77–92 K,</sc> the magnetic field strength range of <sc>0–0.2 T</sc> and the magnetic field angle range of 0°–90°. The results show that the Bi-2223 tape can still bear the practical significance of the superconducting current at <sc>92 K.</sc> If there is no external magnetic field, or the external magnetic field is almost parallel to the HTS tape surface and weaker than <sc>0.1 T,</sc> the critical current in the self-field can still sustain 40%–50% of its critical current at <sc>77 K.</sc> For example, the results of this study have a significant reference price for its use in this temperature range, providing basic information for the creation of cable applications that are superconductive.

Effects of Pulsed Magnetic Fields of Different Intensities on Dislocation Density, Residual Stress, and Hardness of Cr4Mo4V Steel

To study the effects of pulsed magnetic fields of different intensities on the dislocation density, residual stress, and hardness of Cr4Mo4V steel, magnetic treatment is conducted at 0, 1.0, 1.3, 1.5, 2.0, and 2.5 T. The dislocation density and residual stress are measured using Electron Backscatter Diffraction (EBSD) and X-ray technique, respectively. The results reveal the dislocation density and compressive residual stress decrease at lower magnetic fields such as 1.0 T and 1.3 T, while they increase at higher magnetic fields such as 2.0 T and 2.5 T. The average value of kernel averaged misorientation (KAM) and compressive residual stress decrease about 10.4% and 15.8%, respectively, at 1.0 T, while they increase about 5.88% and 18.2%, respectively, at 2.5 T. The average value of hardness decreases about 3.5% at 1.0 T, from 817 HV to 787 HV. With the increments of intensities, the hardness of the treated samples increases. The hardness essentially remains unchanged at 2.0 T and 2.5 T. The reason for the dislocation motion under the action of pulsed magnetic fields is discussed.

Assessment of dynamic characteristics of thin cylindrical sandwich panels with magnetorheological core

Based on the equivalent single-layer linear theory for laminated shells, free and forced vibrations of thin cylindrical sandwich panels with magnetorheological core are studied. Five variants of available magnetorheological elastomers differing in their composition and physical properties are considered for smart viscoelastic core. Coupled differential equations in terms of displacements based on the generalized kinematic hypotheses of Timoshenko accounting for transverse shears with coefficients depending on the complex shear modulus for a smart core are used to govern vibrations of cylindrical panels. Assuming conditions of simple support for straight and curvilinear edges, solutions in the explicit form describing natural modes as well as an equation with respect to the required complex eigenfrequencies are found. To predict the shell response to an external harmonic force, the general solution of non-homogeneous governing equations is derived in the form of series in natural modes. To estimate damping capability of magnetorheological elastomers under consideration, the principle tunable parameters, the lowest natural frequencies and associated logarithmic decrements are calculated for the same panels with different magnetorheological elastomers under the action of a magnetic field of different intensities. Finally, the amplitude–frequency plots for magnetorheological elastomer-based panels of different opening angles with and without magnetic field are presented.

Investigation of the magnetic field effect upon interpolymeric complexes formation based on bovine serum albumin and poly(aspartic acid)

The study presents a novel strategy for obtaining highly ordered interpolymeric complexes based on a protein, bovine serum albumin and a synthetic polymer, poly(aspartic acid). In this approach, experimental tests were carried out in the presence of a magnetic field of different intensities, namely 0.11 T and 0.3 T produced by permanent magnets. The influence of the magnetic force on the complexation process and the resulted self-assembled structures were studied by means of FTIR spectroscopy, X-ray diffraction, DLS, SEM microscopy and in vitro assay. The changes in the FTIR spectra acquired after 24 h of exposure were connected with conformational changes in the secondary structure and increased interactions between polymers, particularly when a higher intensity field was used. Due to a large anisotropy of magnetic susceptibility characteristic to both proteins and polypeptides, the magnetic field generated ordered assemblies consisting in globular structures of nanometric dimensions. This assembly strategy using magnets, along with remote manipulation capability can provide a versatile, contact-free, and inexpensive tool to create new, complex materials with tailorable characteristics.

Green and sustainable methanol production from CO2 over magnetized Fe[sbnd]Cu/core–shell and infiltrate mesoporous silica-aluminosilicates

In this present work, green and efficient utilization concepts in the form of the use of an external magnetic field have been applied to improve catalytic performance in CO2 hydrogenation. The 10Fe10Cu catalysts with two types of supports, core–shell and infiltrate mesoporous silica-aluminosilicate materials, were applied under external magnetic fields of different intensities (0, 20.8 mT, 27.7 mT) and orientations (north-to-south (N–S), south-to-north (S–N) directions). It was found that a magnetic field considerably enhanced both CO2 conversion and methanol and DME selectivities. The highest CO2 conversion was obtained over 10Fe10Cu/infiltrate catalyst under the magnetic field conditions of 27.7 mT and 4N–S direction at 260 °C (conversion was 1.5 times greater than that without a magnetic field). Under such conditions and at 240 °C, the highest methanol and DME space time yields were obtained, with results 1.8–1.9 times higher than those of without a magnetic field. These excellent performances could be ascribed to the superior adsorption of CO2 and H2 reactant gas molecules over the surface of magnetized catalysts under external magnetic field. This leads to the advantages of the catalyzed CO2 hydrogenation–decreases in the operating temperature and simultaneous reduction in CO2 emission to the atmosphere. This therefore facilitates a carbon-neutral route of CO2 utilization.

Impact of Static Magnetic Field on the Antioxidant Defence System of Mice Fibroblasts.

Results of research assessing the biological impact of static magnetic fields are controversial. So far, they have not provided a clear answer to their influence on cell functioning. Since the use of permanent magnets both in everyday life and in industry becomes more and more widespread, the investigations are continued in order to explain these controversies and to evaluate positive applications. The goal of current work was to assess the impact of static magnetic field of different intensities on redox homeostasis in cultures of fibroblasts. The use of permanent magnets allowed avoiding the thermal effects which are present in electromagnets. During the research we used 6 chambers, designed exclusively by us, with different values of field flux density (varying from 0.1 to 0.7 T). We have noted the decrease in the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). The static magnetic fields did not modify the energy state of fibroblasts— adenosine triphosphate (ATP) concentration was stable, as well as the generation of malondialdehyde (MDA)—which is a marker of oxidative stress. Results of research suggest that static magnetic fields generated by permanent magnets do not cause oxidative stress in investigated fibroblasts and that they may show slight antioxidizing activity.

The biological effects of magnetic fields on microvascular endothelial cells in the human brain

Objective To observe the biological effects of magnetic fields of different intensities on microvascular endothelial cells in the human brain (HBMECs). Methods HBMECs were cultured in vitro under normal conditions and randomly divided into a control group and several magnetic induction groups——26 mT, 62.5 mT, 110.7 mT and 215.6 mT at the center pole. Any changes to the cytomembranes were observed 72 h after planking using the lactate dehydrogenase (LDH) method. Superoxide dismutase and malondialdehyde methods were used to detect cellular oxidation due to the magnetic field. An inverted microscope was used to observe any changes in cell morphology, and flow cytometry was employed to detect cell apoptosis. Results Compared with the control group, the LDH value of the 215.6 mT group was significantly higher, but there were no significant differences in oxidative damage, apoptosis or morphology observed. Moreover, there were no significant differences between the controls and the 26 mT, 62.5 mT and 110.7 mT groups in any of the above measurements. Conclusion Magnetic fields of different intensity have different biological effects on HBMECs. A 215.6 mT magnetic field influences their cell membranes but causes no oxidative damage, cell apoptosis or morphological changes. These observations and the mechanism need further exploration. Key words: Magnetic induction; Human brain microvascular endothelial cells; Oxidative damage; Cell apoptosis; Cell morphology

Influence of static magnetic fields up to 700 mT and dihydrochalcones on the antioxidant response in fibroblasts

ABSTRACTThe effects of a static magnetic field (SMF) and the dihydrochalcones phloretin and phloridzin on the redox homeostasis of fibroblasts were investigated. The aim of the present study was to determine the redox homeostasis of fibroblasts that were simultaneously exposed to a static magnetic field and the dihydrochalcones phloretin and phloridzin. The fibroblasts were cultured for 72 h in special magnetic test chambers at different moderate intensities (0.4, 0.55 and 0.7 T). In this report, the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione transferase (GST); the concentrations of malondialdehyde (MDA), adenosine triphosphate (ATP) and total antioxidant status were measured using commercially available kits. We did not observe any impairment in the redox balance in cells in fibroblasts that were only exposed to static magnetic fields of different intensities or In fibroblast cultured with dihydrochalcones and exposed to static magnetic field increase the SOD, GPx, GST activities and MDA concentration. Our investigations revealed that the activities of SOD, GPx, GST and the concentration of MDA that were determined for the fibroblasts that were cultured with dihydrochalcones were higher in the presence of a static magnetic field. Our results indicated that exposure to SMF (0.7 T) with dihydrochalcones induces oxidative stress in fibroblasts.

Effect of static magnetic fields and phloretin on antioxidant defense system of human fibroblasts.

The available evidence from in vitro and in vivo studies is deemed not sufficient to draw conclusions about the potential health effects of static magnetic field (SMF) exposure. Therefore, the aim of the present study was to determine the influence of static magnetic fields and phloretin on the redox homeostasis of human dermal fibroblasts. Control fibroblasts and fibroblasts treated with phloretin were subjected to the influence of static magnetic fields. Three chambers with static magnetic fields of different intensities (0.4, 0.55, and 0.7 T) were used in the study. Quantification of superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (GPX1), microsomal glutathione S-transferase 1 (MGST1), glutathione reductase (GSR), and catalase (CAT) messenger RNAs (mRNAs) was performed by means of real-time reverse transcription PCR (QRT-PCR) technique. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities were measured using a commercially available kit. No significant differences were found in SOD1, SOD2, GPX1, MGST1, GSR, and CAT mRNA levels among the studied groups in comparison to the control culture without phloretin and without the magnet. There were also no changes in SOD, GPx, and CAT activities. In conclusion, our study indicated that static magnetic fields generated by permanent magnets do not exert a negative influence on the oxidative status of human dermal fibroblasts. Based on these studies, it may also be concluded that phloretin does not increase its antioxidant properties under the influence of static magnetic fields. However, SMF-induced modifications at the cellular and molecular level require further clarification.

Variability of the potency of some selected entomopathogenic bacteria (Bacillus spp. and Serratia spp.) on termites, Macrotermes bellicosus (Isoptera: Termitidae) after exposure to magnetic fields

In this study, the effect of exposing entomopathogenic bacteria isolated from macerated termite cadavers to varying intensities of a magnetic field for different periods of time on their pathogenic potential was examined; pathogenicity tests were carried out for each of the bacterial species. Two of the bacteria, Bacillus subtilis (Ehrenberg) Cohn and Serratia marcescens Bizio, were able to induce morbid effects on termites and both were re-isolated from the resulting cadavers. Reinfection using different concentrations of both bacteria was carried out on termites to determine the minimum lethal concentration required for pathogenicity. Bacillus subtilis was able to degenerate the termites at concentration values of 108 colony-forming units (cfu)/ml and S. marcescens at 107 cfu/ml. Both bacteria were then exposed to magnetic fields of different intensities for different periods of time, after which they were used for reinfection of healthy termites. Postinfection study after the exposure of termites to magnetic field-treated bacterial cells revealed no reduction in the entomopathogenic potency of S. marcescens. As the extensive use of chemicals to control insect pests has been found to have detrimental effects on people and the environment, there is a pressing need to discover and develop new entomopathogens to control these insects biologically. Therefore, bacteria discovered in this study to have entomopathogenic potency against termites may be further studied and formulated into either powdery forms or suspensions to be applied to infested wood or wood products.

AN ARGUMENT FOR WEAKLY MAGNETIZED, SLOWLY ROTATING PROGENITORS OF LONG GAMMA-RAY BURSTS

Using binary evolution with Case-C mass transfer, the spins of several black holes (BHs) in X-ray binaries (XBs) have been predicted and confirmed (three cases) by observations. The rotational energy of these BHs is sufficient to power up long gamma-ray bursts (GRBs) and hypernovae (HNe) and still leave a Kerr BH behind. However, strong magnetic fields and/or dynamo effects in the interior of such stars deplete their cores from angular momentum preventing the formation of collapsars. Thus, even though binaries can produce Kerr BHs, most of their rotation is acquired from the stellar mantle, with a long delay between BH formation and spin up. Such binaries would not form GRBs. We study whether the conditions required to produce GRBs can be met by the progenitors of such BHs. Tidal-synchronization and Alfvén timescales are compared for magnetic fields of different intensities threading He stars. A search is made for a magnetic field range that allows tidal spin up all the way in to the stellar core but prevents its slow down during differential rotation phases. The energetics for producing a strong magnetic field during core collapse, which may allow for a GRB central engine, are also estimated. An observationally reasonable choice of parameters is found (B ≲ 102 G threading a slowly rotating He star) that allows Fe cores to retain substantial angular momentum. Thus, the Case-C mass-transfer binary channel is capable of explaining long GRBs. However, the progenitors must have low initial spin and low internal magnetic field throughout their H-burning and He-burning phases.

Numerical and Experimental Study of Rayleigh–Bénard–Kelvin Convection

We performed experimental and numerical studies of combined effects of thermal buoyancy and magnetization force applied on a cubical enclosure of a paramagnetic fluid heated from below and cooled from top. The temperature difference between the hot and cold wall was kept constant. After considering neutral situation (i.e. a pure natural convection case), magnetic fields of different intensity were imposed. The magnetization force produced significant changes in flow (transition from laminar to turbulent regimes), wall-heat transfer (enhancement) and turbulence (turbulence structures reorganization). The strong magnetic field and its gradients were generated by a superconducting magnet which can generate magnetic field up to 10 T and where gradients of the magnetic induction can reach up to 900 T2/m. A good agreement between experiments and numerical simulations was obtained in predicting the integral wall heat transfer over entire range of considered working parameters. Numerical simulations provided a detailed insights into changes of the local wall-heat transfer and long-term time averaged first and second moments for different strengths of the imposed magnetic induction.

Effect of a Static Magnetic Fields and Fluoride Ions on the Antioxidant Defense System of Mice Fibroblasts

The results of studies on the biological influence of magnetic fields are controversial and do not provide clear answers regarding their impact on cell functioning. Fluoride compounds are substances that influence free radical processes, which occur when the reactive forms of oxygen are present. It is not known whether static magnetic fields (SMF) cause any changes in fluoride assimilation or activity. Therefore, the aim of this work was to determine the potential relationship between magnetic field exposure to, and the antioxidant system of, fibroblasts cultured with fluoride ions. Three chambers with static magnetic fields of different intensities (0.4, 0.6, and 0.7 T) were used in this work. Fluoride ions were added at a concentration of 0.12 mM, which did not cause the precipitation of calcium or magnesium. The results of this study show that static magnetic fields reduce the oxidative stress caused by fluoride ions and normalize the activities of antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Static magnetic fields modify the energy state of fibroblasts, causing an increase in the ATP concentration and a decrease in the MDA concentration. These results suggest that exposure to fluoride and an SMF improves the tolerance of cells to the oxidative stress induced by fluoride ions.