Effect Of Pulsed Magnetic Field Research Articles

Pain-relieving effects of pulsed magnetic fields in a rat model of carrageenan-induced hindpaw inflammation

Purpose: Many strategies have been investigated to exclude the several side-effects of pharmacological or invasive treatments. Non-invasive pulsed magnetic field (PMF) treatment with no toxicity or side-effects can be an alternative to pharmacologic treatments. The purpose of this study was, therefore, to investigate the pain-relieving effects of PMF treatment in the inflammatory pain conditions.Materials and methods: Effects of PMF treatment on the hallmarks of the inflammatory pain indices such as hyperalgesia, allodynia, edema and several biochemical parameters that evaluate oxidative stress were investigated using a well established carrageenan (CAR)-induced hindpaw inflammation model in rats.Results: CAR injection lowered the paw withdrawal thermal latencies (hyperalgesia) and mechanical thresholds (allodynia). CAR also decreased the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) levels and increased malondialdehyde (MDA) levels compared with healthy rat paw tissues. PMF treatment produced significant increases in the thermal latencies and mechanical thresholds in CAR-injected paws. In the inflamed paw tissues, PMF increased the activities of SOD, CAT and GPx and decreased MDA level. We also demonstrated that PMF decreased paw mass indicating that it has an anti-edematous potential.Conclusions: The present results reveal that PMF treatment can ameliorate the CAR-induced inflammatory pain indices such as mechanical allodynia, thermal hyperalgesia and edema, and attenuate the oxidative stress. The action mechanisms of PMF in CAR-induced inflammation might be related to the increases in the levels of antioxidant enzymes in inflamed tissues. The findings suggest that PMF treatment might be beneficial in inflammatory pain conditions.

Clodronate changes neurobiological effects of pulsed magnetic field on diabetic rats with peripheral neuropathy

Several studies have reported that pulsed magnetic fields (PMFs) can be a choice of therapy for diabetic peripheral neuropathy. However, the exact underlying mechanism of PMF is still not known. The purpose of this study was, therefore, to investigate the effects of clodronate encapsulated with liposome, a specific agent depleting macrophage, on PMF-treated streptozotocin-induced type I diabetic rats with peripheral neuropathy. Effects of PMF, liposome-encapsulated clodronate (LEC) or their combined treatments were investigated in diabetic rats by measuring the thermal latencies, mechanical thresholds, whole blood glucose levels, serum insulin level, and body mass. In diabetic rats, PMF exhibited a decrease in the blood glucose levels but did not change the serum insulin level. Both mechanical thresholds and thermal latencies of diabetic rats enhanced throughout the PMF treatment. During the PMF treatment, the administration of LEC suppressed the PMF-induced decrease in blood glucose level, PMF-induced increase in mechanical threshold and thermal latencies in diabetic animals. In addition, PMF reduced the LEC-induced increase in insulin levels of diabetic rats. Findings demonstrated that although effects of both PMF alone and LEC alone on diabetic animals are mostly positive, LEC may remove the therapeutic efficacies of PMF in combined treatment.

Sleep EEG alterations: effects of pulsed magnetic fields versus pulse‐modulated radio frequency electromagnetic fields

Studies have repeatedly shown that electroencephalographic power during sleep is enhanced in the spindle frequency range following radio frequency electromagnetic field exposures pulse-modulated with fundamental frequency components of 2, 8, 14 or 217 Hz and combinations of these. However, signals used in previous studies also had significant harmonic components above 20 Hz. The current study aimed: (i) to determine if modulation components above 20 Hz, in combination with radio frequency, are necessary to alter the electroencephalogram; and (ii) to test the demodulation hypothesis, if the same effects occur after magnetic field exposure with the same pulse sequence used in the pulse-modulated radio frequency exposure. In a randomized double-blind crossover design, 25 young healthy men were exposed at weekly intervals to three different conditions for 30 min before sleep. Cognitive tasks were also performed during exposure. The conditions were a 2-Hz pulse-modulated radio frequency field, a 2-Hz pulsed magnetic field, and sham. Radio frequency exposure increased electroencephalogram power in the spindle frequency range. Furthermore, delta and theta activity (non-rapid eye movement sleep), and alpha and delta activity (rapid eye movement sleep) were affected following both exposure conditions. No effect on sleep architecture and no clear impact of exposure on cognition was observed. These results demonstrate that both pulse-modulated radio frequency and pulsed magnetic fields affect brain physiology, and the presence of significant frequency components above 20 Hz are not fundamental for these effects to occur. Because responses were not identical for all exposures, the study does not support the hypothesis that effects of radio frequency exposure are based on demodulation of the signal only.

Effect of pulse magnetic field stimulation on calcium channel current

This study aimed to investigate the effect of low frequency and high amplitude pulse magnetic field (PMF) on Calcium ion channel current of cells. Measurements were done on the Human Embryonic Kidney 293 cells (HEK 293), which have only Calcium ion channels functioning. The whole cell current was measured by patch clamp method, with the clamped voltage ramping from −90mV to +50mV across the cell membrane. A PMF was generated by a 400-turn coil connected to a pulse current generator. The frequency of the pulse was 7Hz, the width of the pulse was 3ms, and the amplitude of the pulse, or the flux density, was ranging from 6 to 25mT. The results showed that the profile of the whole cell Calcium channel current could be modified by the PMF. With the PMF applied, the phase shifting occurred: the onset of the channel opening took place several mili-seconds earlier than that without the PWF and correspondingly, the whole cell current reached its maximum earlier, and the current returned back to zero earlier as well. When the PWF was stopped, these effects persisted for a period of time, and then the current profile “recovered” to its original appearance. The decrease of the onset time and peak current time could be due to the local electric potential induced by the PWF and the direct interaction between PMF and ion channels/ions. The exact mechanisms of the observed effects of PMF on the cell are still unknown and need to be further studied.

Effect of pulsed magnetic field annealing on the microstructure and texture of grain-oriented silicon steel

The effect of pulsed magnetic primary annealing on the microstructure and texture of two-stage cold-rolled silicon steel is investigated. Specimens are annealed at 700°C for 1h under a 1T pulsed magnetic field along different directions with respect to the sample coordinate system. Crystallographic orientation and grain size are identified by analyzing electron backscattered diffraction pattern. The effects of magnetic field treatment are related to the magnetic field direction. Based on the anisotropy energy of ferromagnetic material during magnetic annealing, a hypothesis is proposed. All of the experimental results in this work support the proposed model.

Effects of pulsed magnetic field on Mn-doped ZnO diluted magnetic semiconductor prepared by hydrothermal method

In this study, zinc acetate, manganese acetate, ammonium hydroxide and ammonium chloride are used as the source materials to prepare crystalline Mn-doped ZnO diluted magnetic semiconductor by hydrothermal method under a 4 T pulsed magnetic field. The microstructures, morphologies and magnetic properties of the samples are characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman scattering spectra, Photoluminescnce and vibrating sample magnetometer. The effect of pulsed magnetic field on the microstructure and magnetic property of the Mn-doped ZnO diluted magnetic semiconductor are discussed. The result indicates that all the samples are still of hexagonal wurtzite structure. The pulsed magnetic field promotes the crystal growth, and improves room temperature ferromagnetism. The saturation magnetization (0.028 emu/g) of the sample fabricated under 4 T pulsed magnetic field is more than two times that of the sample synthesized without pulsed magnetic field. The Curie temperature (Tc) of the Mn-doped ZnO increases 15 K through the pulsed magnetic field processing.

Synthesis of Cr-doped ZnO diluted magnetic semiconductor by hydrothermal method under pulsed magnetic field

In this study, zinc chloride, chromic chloride, ammonium hydroxide and ammonium chloride are used as the source materials to prepare the crystalline Cr-doped ZnO diluted magnetic semiconductor by the hydrothermal method under a 4-T pulsed magnetic field. The structures and the morphologies of the samples are characterized by X-ray diffraction and scanning electron microscope. The magnetic analysis of the specimens is performed by vibrating sample magnetometer. The effects of pulsed magnetic field on the microstructure and the magnetic properties of the Cr-doped ZnO are discussed. The result indicates that all the samples still have hexagonal wurtzite structures. The pulsed magnetic field is conducive to promote the crystal growth orientation. The sample fabricated under pulsed magnetic field exhibits good room temperature ferromagnetism. The saturation magnetization is 0.068 emu/g. However, the sample synthesized without magnetic field shows paramagnetism at room temperature. The Curie temperature (Tc) of the Cr-doped ZnO is increased by 16 K through the pulsed magnetic field processing.

Effects of Pulsed Magnetic Field Stimulus on Electroencephalogram Alpha Activity

We investigated the effects of pulsed magnetic field (pMF) stimulus on electroencephalogram alpha activity when applied for various durations at the PC9 and/or HT9 acupoints. The maximum increase in alpha activity occurred after the stimulus was applied to the acupoints for 3 min. It can be concluded that pMF stimulus can be used in an alternative noninvasive acupuncture therapy, in which correct pMF stimulus induces a relaxed mental state.

THE EFFECT OF PULSED MAGNETIC FIELD ON HORSERADISH PEROXIDASE

ABSTRACTThe effect of pulsed magnetic field (PMF) on the activity and structure of horseradish peroxidase (HRP) in buffer solution was investigated. HRP was inactivated when exposed to PMF at field strengths of 2.0, 3.0 and 4.0 tesla (T) for 5 to 40 pulses. The maximum inactivation of HRP was achieved at 4.0 T for 40 pulses, in which 67.67% of the enzyme activity was lost. Further experiments showed that the activity of HRP was not significantly affected by either storage time at 4C or the heat produced during lower intensity PMF (from 1.0 to 3.0 T). The inactivation data were adjusted to the Bigelow, Hülsheger and Weibull models. Results showed that the Weibull model successfully described the relationship between residual activity of HRP and pulse strength as well as pulse number. Ultraviolet and intrinsic fluorescence spectra analysis proved that the PMF‐induced inactivation correlated with alteration of the tertiary structure of HRP.PRACTICAL APPLICATIONSAs a kind of enzyme present in many foods, when peroxidase (POD) is exposed to air, it will catalyze some reactions which have a negative effect on sensorial and nutritional qualities of the food. In this article, pulsed magnetic field was proved to be a potential processing method to inactivate POD without destroying the sensorial and nutritional qualities. The kinetic models also offer some parameters for designing methods to prolong shelf life of agricultural products.

Effect of magnetic field on phase morphology transformation of MnO2 nanostructures in a hydrothermal process

AbstractMnO2 nanostructures with various phases and morphologies were successfully synthesized by a magnetic‐field‐assisted hydrothermal approach. By applying a pulsed magnetic field to the reaction system, the phase and morphology transformation progress, i.e. urchin‐like α‐ and γ‐MnO2 nanostructures converting to β‐MnO2 nanowires was interfered comparing with those reacted without magnetic field. The effect of pulsed magnetic field on the growth of MnO2 was investigated by tracking the evolution of phase and morphology of the samples at different reaction stages by using X‐ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. It is found that the pulsed magnetic field obviously affects the nucleation and growth of MnO2 nanostructures and therefore influences the phase and morphology transformation of MnO2. The transformation mechanism for the MnO2 nanostructures in hydrothermal treatment is the well‐known “Ostwald ripening process”. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of pulsed magnetic field on microstructures and morphology of the primary phase in semisolid A356 Al slurry

A novel technique for introducing pulsed magnetic field (PMF) during isothermal holding period of A356 Al alloy has been employed to prepare semisolid slurry. The effects of vibration frequency of PMF on morphology of the primary phase in semisolid A356 Al alloy slurry were studied, and some characteristic parameters characterized the morphology and grain size of the primary phase were obtained. The results show that the primary α-Al particles become smaller and rounder with the increase of vibration frequency. The slurry with primary α-Al particle average diameter of about 79 μm and average shape factor of about 0.58 can be prepared under the action of a PMF at 10 Hz and 600 °C for 4 min. It is feasible to use PMF processing to prepare semisolid alloy slurry, because of its strong forced convection within the whole bulk melt.

Grain refinement of as-cast superalloy IN718 under action of low voltage pulsed magnetic field

The grain refinement of superalloy IN718 under the action of low voltage pulsed magnetic field was investigated. The experimental results show that fine equiaxed grains are acquired under the action of low voltage pulsed magnetic field. The refinement effect of the pulsed magnetic field is affected by the melt cooling rate and superheating. The decrease of cooling rate and superheating enhance the refinement effect of the low voltage pulsed magnetic field. The magnetic force and the melt flow during solidification are modeled and simulated to reveal the grain refinement mechanism. It is considered that the melt convection caused by the pulsed magnetic field, as well as cooling rate and superheating contributes to the refinement of solidified grains.

Magnetic-Field-Assisted Hydrothermal Growth of Manganese Dioxide Nanostructures and their Phase Transformation

MnO2 nanostructures were successfully synthesized by a magnetic-field-assisted hydrothermal approach. By applying a pulsed magnetic field to the reaction system, the crystal phase transformation progress of MnO2 at different temperature has been changed comparing to those synthesized without magnetic field. The effect of pulsed magnetic field on the growth of MnO2 was investigated by tracking the phase of the sample by using X-ray diffraction. It is found the pulsed magnetic field has an obvious effect on the nucleation and growth of MnO2 nanostructures and therefore influences the phase transformation.

Effects of pulsed magnetic fields on the light scattering property of the freezing process of aqueous solutions

The purpose of the study is to clarify the effect and mechanism of magnetic fields on freeze processes in aqueous solutions. In the present study, an ice crystal formation process in biological aqueous solutions under pulsed train magnetic fields (PMF) of up to 325 T/s at 6.5 mT was observed. The pulsed magnetic field generators were set in a freezer, which controlled the temperature between 10C and −30 °C. During ice formation in the aqueous solution, disk-like ice crystal domains appeared, and the PMF-exposure exhibited a vibration of floating objects in the induced electric field directions under the cooled condition when the pulsed train frequency was changed between 10 and 17 Hz. In the freezing process of the aqueous solution with NaCl, the scattered light transmission of the ion containing the aqueous solution increased in the early phase of freezing, and then began to decrease during the late phase when the ice coagulation proceeded. The PMF exposure enhanced the light-scattering increase and decrease in the early and late phases, respectively. The results suggested that a fine ice crystal, which strongly scattered the irradiated light, increased in number in the early phase of the supercooled state when the PMF was applied.

Microstructural Refinement Process of Pure Magnesium by Pulse Magnetic Field Treatment

The effects of pulsed magnetic field on the solidified structure of pure Mg were investigated. Fine uniform equiaxed grains are acquired in the whole ingot from the PMF treatment, in contrast with the coarse columnar grains observed in conventional casting, and the average grain size is refined to 260 m with a 5Hz PMF treatment. The mould size also affects the grain refinement and the most suitable inner diameter of the cylindrical mould is set at 50mm. Pulsed magnetic field increases melt convection during solidification, and the violent agitation causes warmer liquid to fracture the tip of columnar dendrites or to break off dendrite branches and promote the formation of an equiaxed structure, with the broken pieces transported into the bulk liquid acting as nuclei.

27 NEW FREEZING METHOD BY PULSED MAGNETIC FIELD EFFECTS; WHOLE OVARIES OF CYNOMOLGUS MONKEYS AND RABBITS

Introduction: There have been 12 birth reports following autotransplantation of frozen thawed ovaries so far. However, the function of frozen thawed ovaries does not last long due to follicle loss during the freezing-thawing and reimplantation process without anastomosis. Our objective was to establish a technique to cryopreserve the entire ovary, improve the recovery rate of ovarian cells, and maintain long-term ovarian function after transplantation. We report the successful transplantation of ovaries in cynomolgus monkeys and rabbits after cryopreservation by pulsed magnetic field effects.

Time domain characterization of magnetoelastic sensors: A pulse method for resonance frequency determination

This paper presents a pulse method for determination of resonance frequency of magnetoelastic sensors. The method eliminates the bias field that is necessary in previous methods and also allows fast and accurate detection. The stability tests of the system show an average standard deviation of 129 Hz and an average drift of -10.4 Hz/h. This system allows simultaneous detection of two sensors. A simulation of the operation of one and two sensors was shown to be very similar to the real data plots from the test system. Real tests have shown that adding a second sensor does not affect the resonance frequency of the first sensor. The effect of pulse magnetic field on the characteristics of the resonance signal, including resonance frequency, amplitude, and Q-value of frequency domain signal, has been studied and real time detection using magnetoelastic sensors was demonstrated in a flowing system.

Evidence for a dose-dependent effect of pulsed magnetic fields on pain processing

Functional magnetic resonance imaging (fMRI) was used to investigate the dose–response relationship (sham, 100, 200, 1000 μT) between a pulsed extremely low frequency magnetic field (ELFMF) and acute thermal pain on the dominant right hand. Forty-seven participants were recruited, and pulsed ELFMF was applied through the MRI gradient system using a novel technique. Regions of interest (ROIs) matching those of previous studies were examined for a potential dose response. Significant correlations between applied field strength and change in BOLD activity were found in the anterior cingulate and the ipsilateral insula, indicating that there might be either a dose response or a threshold effect of the ELFMF.

The effects of a pulsed magnetic field on carotid restenosis and the expression of matrix metalloproteinase-2 in vascular smooth muscle cells

Objective To investigate the effects of pulsed magnetic fields of different intensity on carotid restenosis (CRS), post carotid endarterectomy (CEA) and the expression of matrix metalloproteinase-2 (MMP-2)in vascular smooth muscle cells (VSMC). Methods An animal model of carotid altherosclerosis was established in 50 New Zealand rabbits by using air-drying lesions combined with high fat feed. After two months, the rabbits were treated with bilateral CEA, and then divided randomly into 3 groups. Two of the groups were treated with ei-ther 0.6 or 1.0 T pulsed magnetic fields, while the third group served as an untreated blank control. Changes in the pathology of the tunica intima were observed 1, 2 and 3 months after the CEA using morphologic analysis, and the expression of MMP-2 in the VSMC was determined using immunohistochemistry. Results The histological a-nalysis showed that the total luminal area, plaque area, the maximum plaque thickness and the proportion of siena-sis in the treated groups were all significandy lower, on average, than in the control group. At all three time points the average improvements in the 1.0 T group were significantly greater than in the 0.6 T group. The average ex-pression of MMP-2 in the treated groups was significantly lower than in the control group, especially in the 1.0 T group. Conclusions Pulsed magnetic field therapy positively influences CRS and the expression of MMP-2 in VSMC. Reduced MMP-2 expression might be one of the mechanisms through which pulsed magnetic fields prevent or lessen carotid restenosis post CEA. Key words: Carotid restenosis; Pulsed magnetic fields; Vascular smooth muscle cells; Matrix metal-loproteinase-2

Grain refinement effect of pulsed magnetic field on solidified microstructure of superalloy IN718

The refinement mechanism of pulsed magnetic field (PMF) was discussed by experimental investigation, and the effects of exciting frequency, exciting voltage, and delay time of PMF on grains refinement of superalloy were studied. The experimental results show that, as exciting frequency or exciting voltage is increased, the grains are refined. However, the grains become coarse when frequency increases further. As delay time of PMF increases, the grain size increases. The refinement effect of PMF is attributed to the detachment of heterogeneous nuclei on the mold wall and subsequently separation of nuclei in the melt. The Joule heat can prolong the continuous nucleation process. However, the refinement effect will be impaired if the Joule heat is strong enough to remelt the detached nuclei.