Low-intensity Magnetic Field Research Articles

Liposome Fusion Mediated by Hydrophobic Magnetic Nanoparticles Stabilized with Oleic Acid and Modulated by an External Magnetic Field.

Membrane fusion is considered relevant in countless scientific areas and biotechnological processes, ranging from vital life events to biomedicine, pharmaceuticals, and materials engineering, among others. In this study, we employed hydrophobic oleic acid (OA)-coated magnetite (Fe3O4) nanoparticles (MNP-OA) as a platform to induce the fusion of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine liposomes [large unilamellar vesicles (LUVs)] in a colloidal dispersion. This fusion was monitored through dynamic light scattering, turbidimetry, and fluorescence assay using the well-known Tb/dipicolinic acid (DPA) complex formation assay. MNP-OA have shown to be able to induce fusion with the mixing of liposomal inner content with direct dependence on the nanoparticle concentration added to the LUVs. Moreover, changes in the permeability of the liposome bilayer, upon the addition of MNP-OA to liposomes, were evaluated by studying the leakage of carboxyfluorescein and of the co-encapsulated Tb/DPA complex. These assays allowed us to determine that MNP-OA did not significantly modify liposome permeability during the fusion process. Transmission electron microscopy and confocal microscopy revealed that MNP-OA remained embedded in the lipid bilayer without producing membrane rupture, liposome deformation, or destruction. In addition, we evaluated the effect of applying a low-intensity magnetic field to the LUVs/MNP-OA system and observed that the nanoparticles considerably increased their fusogenic activity under this external stimulus, as well as they are capable of responding to low magnetic fields of around 0.45 mT. These results revealed the potential of hydrophobic magnetic nanoparticles, stabilized with OA, to act as a fusogen, thus representing a valuable tool for biotechnological applications.

Research on controlling the perfect transfer of the two-qubit quantum information in spin chain

Perfect transfer of the two-qubit quantum information in spin chain without any magnetic field is investigated. In our work, the spin chain is placed in a particular low-intensity magnetic field whose value is symmetrical about the chain and whose difference value between the nearest lattice points is constant. And the influence of the magnetic field has been studied by the method of matrix diagonalization. It is shown that the difference value of the magnetic field determines the fidelity of the two-qubit quantum information transfer in the spin chain. On the basis of this, we propose a theoretical scheme to achieve the quantum control of the two-qubit quantum information perfect transfer by applying this magnetic field, so that the perfect transfer time of information can be controlled arbitrarily as needed.

Statik Manyetik Alanın Trombosit Agregasyonuna Etkisi

Objective: Platelets are 4-7 Micron diameter blood cells that play an important role in coagulation and inflammation with the substances they secrete and the membrane proteins. Although there are many studies investigating the effect of a magnetic field on living organisms and blood cells, it’s mechanism has not been clarified yet. It has been demonstrated that the low-intensity magnetic field activates the leukocytes and increases their number, but there are controversial data regarding its effect on platelets. In this study, we aimed to examine the effects of a magnetic field on platelet functions. Materials and Methods: Platelets were exposed to different intensities of magnetic field (2mT, 5mT, 40mT) at different times (5, 15 and 30 minutes) and the aggregation of platelets was detected at different time intervals (0, 24, 40, 48 hours) using the aggregometer.The platelet aggregation curve was determinated as slope and amlitude (%). Results: After a 15´ and 30´ incubation at 5mT, platelet aggregation at the 24th hour was found to be higher than the control (Slope p=0.008, Amplitude p=0.026). There was no statistical difference between 15 and 30 minutes. The 48th hour aggregation was found to be significantly higher than the control after a 15´ and 30´ incubation at 2mT (p=0.038). Platelet aggregation at 2mT was higher than platelet aggregation at 5mT (p=0.032). Conclusion: It was determined that there was an increase in aggregation of platelets exposed to a magnetic field. The fact that 2mT static magnetic field exposure positively affects the platelet aggregation even after 48 hours, suggests that this effect will enable the platelets to maintain their activities outside of the body for a longer time.

The Effect of a Magnetic Field and Low-Intensity Laser Irradiation on the Destructive Activity of Filamentous Fungi During their Growth on a Number of Industrial Products

An assessment of the impact of low-intensity laser irradiation (LILI) and magnetic field (MF) on the biodegradation of a number of industrial products: wood fiberboard (WFB) and polyester caused by filamentous fungi is presented. It has been established that the magnetic field is capable of causing intensive destruction of wood fiberboard and polyester by fungi Alternaria alternata, Aspergillus niger, then the destructive process of WFB in the case of Penicillium cyclopium remained at the control level, and in the case of polyester it slowed down. The action of LILI, on the contrary, increased the destructive activity of Penicillium cyclopium in variants with WFB, and for polyester in the fungi Alternaria alternata, Aspergillus niger. Differences in the change in the resistance of products to fungi under the action of LILI and MF can be associated with both the physiological and biochemical characteristics of fungi and the aging process of polymers under the influence of the studied physical factors.

Quantum control of quantum information perfect transfer in arbitrary-length spin chain

The single-bit quantum information perfect transfer determined only by the dynamic evolution of the system in a spin chain is investigated. Our results show that the quantum control of the above quantum information perfect transfer can be achieved by applying a low-intensity symmetric magnetic field to the spin chain. We have studied the influence of the magnetic field on the perfect transfer of quantum information in the arbitrary-length spin chain. It gives that the time of the quantum information perfect transfer is determined by applying the low-intensity magnetic field which is symmetric about the spin chain and whose difference value is constant between the closed lattices in the spin chain. Furthermore, we put forward a scheme to achieve the quantum control of quantum information perfect transfer in the arbitrarily-length spin chain by applying the magnetic field.

Application of rhythmic transcranial magnetic stimulation with low-intensive running pulsed magnetic field in the rehabilitation of patients with post-stroke cognitive impairment syndrome

The purpose of the investigation was to study the nootropic effects of rhythmic transcranial magnetic stimulation (rTMS) using low-intensity magnetic field with the induction rate of 45 mT, base frequency of 50 Hz, modulation frequency of 10 Hz in combination with standard medical and psychological therapy in the rehabilitation of patients with post-stroke cognitive impairment (PSCI).
 Materials and methods. The rehabilitation outcomes in 98 patients with PSCI syndrome were studied. The patients were subdivided into 2 groups: 53 patients of the control group were treated with the standard nootropic medications and neuropsychological procedures; 45 patients of the main group were additionally treated with rTMS by the low-intensive running pulsed magnetic field of 10 Hz modulation frequency. The dynamics of the score increase according to Rivermid, Karnovsky, Roshina, MMSE, mRS, HDRS, SF-36 scales were analyzed.
 Conclusion. Application of rTMS with low-intensive running pulsed magnetic field of 10 Hz modulation frequency in combination with a standard program of cognitive rehabilitation contributes to a significant improvement in the recovery of mental calculation function in ischemic stroke patients, as well as normalization in mood swings in the patients who had suffered a hemorrhagic stroke and post-stroke depression. This variant of rTMS can be safely used in patients with PSCI syndrome in the early recovery period, 3 weeks after the onset of stroke.

Design, implementation and experimental characterisation of a high sensitivity GMI gradiometer with an interference compensation system

The giant magneto-impedance (GMI) effect has been, since its discovery, one of the most promising technologies in the development of magnetic sensors. Features such as high sensitivity, stability and low cost are the main reasons for the development of this type of magnetometers. This study reports the design, implementation and experimental characterisation of a high sensitivity GMI gradiometer, aimed at measuring low-intensity magnetic fields. A first-order gradiometer was designed, based on the impedance phase characteristics of two Co 70 Fe 5 Si 15 B 10 amorphous ribbon-shaped sensors connected to an electronic circuit that converts the magnetic field into an output voltage. The developed prototype can operate not only as gradiometer but also as two separate magnetometers, which allows it to incorporate a compensation system against deviations in the biasing field of the GMI sensors. The experimental results for the gradiometer showed a sensitivity of 99 mV/μT, a measuring range of ±30 μT, a magnetic noise of 5 nT Hz -1/2 at 5 Hz and a resolution of 40 nT within a 500 Hz bandwidth. The compensation system has shown a settling time of 1.6 s for perturbations in the range ±10 μT with a steady-state error <;0.02%. All experiments were performed in an unshielded environment.

Electromagnetic instabilities in weakly relativistic plasmas

The spin-orbit coupling effects on the velocity space electromagnetic instabilities have been analytically studied. In this order, first, a suitable form of the kinetic theory is introduced and then, results are investigated for real ICF and astrophysical plasmas. For the ICF plasmas, Low intensity magnetic field can not provide a suitable field for effectiveness of the particle’s spin, while transmission to astrophysical subjects is different. For astrophysical applications, the spin-orbit coupling effects can lead to addition free energy so that, it can overcoming the non relativistic effects and leads to increasing the instability growth rate.

The Simulation and Optimization of an Electromagnetic Field in a Vertical Continuous Casting Mold for a Large Bloom

The electromagnetic model of a large-bloom continuous casting was established to simulate the magnetic field. The model 3600 digital, high-precision, three-dimensional Gaussian meter was used to measure the internal magnetic field of mold electromagnetic stirring (M-EMS). The distribution of simulated magnetic field was basically consistent with that of the measured magnetic field; the accuracy of electromagnetic stirring model was verified. With the increase of current frequency, the electromagnetic force first increases and then decreases; when the current frequency is 9 Hz, the electromagnetic force reaches its maximum value. A bipolar electromagnetic stirring model is proposed; the influence of current intensity and distance were investigated. With the increase of current intensity of lower mold electromagnetic stirring (M-EMSB), the internal magnetic intensity of upper mold electromagnetic stirring (M-EMSA) gradually increases, and the middle region is gradually filled by magnetic field. With the increase of the distance, the range of the low-intensity magnetic field expands. When the current intensity of the M-EMSB is 320 A, and the distance is 400 mm, an 8 mT uniform magnetic field in the range of 1.2 m is formed. Compared with the traditional continuous casting electromagnetic agitator, the center equiaxial crystal of bipolar electromagnetic agitator increases from 30.3% to 49.5%.

Effect of Low Intensity Magnetic Field Stimulation on Calcium-Mediated Cytotoxicity After Mild Spinal Cord Contusion Injury in Rats.

Background:Magnetic field (MF) stimulation has the potential to reduce secondary damage and promote functional recovery after neural tissue injury. The study aimed to observe the effect of very low intensity (17.96µT) MF on general body condition, secondary damage, pain status, and locomotion.Methods:We exposed rats to MF (2 h/day × 3 weeks) after 6.25 mm contusion spinal injury. Locomotor behavior was evaluated by BBB score, pain assessment was done by recording threshold for tail flick, expression of voltage-gated calcium channels and extent of secondary damage in the spinal cord was assessed by immunofluorescence and Cresyl violet staining, respectively.Results:A significant (p ≤ .001) improvement in bladder function as well as BBB score was observed after MF exposure in comparison with sham and SCI over the observation period of 3 weeks. SCI group showed an increase in the threshold for vocalization after discharge, which decreased following MF exposure. Cresyl violet staining showed significantly higher tissue sparing (73%) at the epicenter after MF exposure when compared to SCI group. This was accompanied with a significant decrease in calcium channel expression in MF group as compared to SCI.Conclusion:The results suggest facilitation of sensory-motor recovery after MF exposure, which could be due to attenuation of secondary damage and calcium-mediated excitotoxicity in a mild contusion rat model of SCI.

2019 APHRS expert consensus statement on three-dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS.

2019 APHRS expert consensus statement on three-dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS.

Signatures of Coronal Loop Opening via Interchange Reconnection in the Slow Solar Wind at 1 AU

The opening of closed magnetic loops via reconnection with open solar flux, so called “interchange reconnection”, is invoked in a number of models of slow solar wind release. In the heliosphere, this is expected to result in local switchbacks or inversions in heliospheric magnetic flux (HMF). When observed at 1 AU, inverted HMF has previously been shown to exhibit high ion charge states, suggestive of hot coronal loops, and to map to the locations of coronal magnetic separatrices. However, simulations show that inverted HMF produced directly by reconnection in the low corona is unlikely to survive to 1 AU without the amplification by solar wind speed shear. By considering the surrounding solar wind, we show that inverted HMF is preferably associated with regions of solar wind shear at 1 AU. Compared with the surrounding solar wind, inverted HMF intervals have lower magnetic field intensity and show intermediate speed and density values between the faster, more tenuous wind ahead and the slower, denser wind behind. There is no coherent signature in iron charge states, but oxygen and carbon charge states within the inverted HMF are in agreement with the higher values in the slow wind behind. Conversely, the iron-to-oxygen abundance ratio is in better agreement with the lower values in the solar wind ahead, while the alpha-to-proton abundance ratio shows no variation. One possible explanation for these observations is that the interchange reconnection (and subsequent solar wind shear) that is responsible for generation of inverted HMF involves very small, quiet-Sun loops of approximately photospheric composition, which are impulsively heated in the low corona, rather than large-scale active region loops with enhanced first-ionisation potential elements. Whether signatures of such small loops could be detected in situ at 1 AU still remains to be determined.

Magnetic field intervention on growth of the filamentous microalgae Tribonema sp. in starch wastewater for algal biomass production and nutrients removal: Influence of ambient temperature and operational strategy

This paper investigated the effects of temperature and cultivation methods (batch or semi-continuous culture) on the filamentous microalgae Tribonema sp. biomass production and nutrients removal in starch wastewater under low intensity magnetic field (MF) intervention. The MF significantly promoted algal growth in the late logarithmic-phase of batch cultivation, and the effect was even more obvious at lower temperatures. The MF treated group at 30 °C accumulated the highest biomass of 4.44 g/L of batch culture, an increase of 15.0% compared with the control group. The oil content of Tribonema sp. was enhanced with the MF intervention, especially for the batch culture. In the semi-continuous culture under MF intervention, Tribonema sp. reached the high biomass of 18.45 g/L after 25 days. When gradually reducing hydraulic retention time (HRT) to 1 day, the average removal rates for COD, TN, NH3-N and TP were all more than 90% in the semi-continuous cultivation.

The effect of magnetic field exposure on differentiation of magnetite nanoparticle-loaded adipose-derived stem cells.

Magnetic nanoparticles (MNPs) are versatile tools for various applications in biotechnology and nanomedicine. MNPs-mediated cell tracking, targeting and imaging are increasingly studied for regenerative medicine applications in cell therapy and tissue engineering. Mechanical stimulation influences mesenchymal stem cell differentiation. Here we show that MNPs-mediated magneto-mechanical stimulation of human primary adipose derived stem cells (ADSCs) exposed to variable magnetic field (MF) influences their adipogenic and osteogenic differentiation. ADSCs loaded with biocompatible magnetite nanoparticles of 6.6nm, and with an average load of 21 picograms iron/cell were exposed to variable low intensity (0.5mT - LMF) and higher intensity magnetic fields (14.7 and 21.6mT - HMF). Type, duration, intensity and frequency of MF differently affect differentiation. Short time (2days) intermittent exposure to LMF increases adipogenesis while longer (7days) intermittent as well as continuous exposure favors osteogenesis. HMF (21.6mT) short time intermittent exposure favors osteogenesis. Different exposure protocols can be used to increase differentiation dependently on expected results. Magnetic remotely-actuated MNPs up-taken by ADSCs promotes the shift towards osteoblastic lineage. ADSCs-MNPs under MF exposure could be used for enabling osteoblastic conversion during cell therapy for systemic osteoporosis. Current results enable further in vivo studies investigating the role of remotely-controlled magnetically actuated ADSCs-MNPs for the treatment of osteoporosis.

Indukcione zavojnice za merenje kvazistacionarnih magnetnih polja niskog intenziteta

Short air core induction coils with a large radius and a large number of turns can be successfully used as induction sensors for detecting low-intensity quasistationary magnetic fields, such as magnetic fields of ships. The application of these sensors is presented in detail, and then a practical methodology for determining all the necessary parameters of the sensor is proposed. The sensitivity of sensors with actual design parameters is determined and inductance is calculated in several ways. The practical results of ship's magnetism measurement and the calculation of all parameters of the coil are presented. A comparative analysis of all results was performed and the observed deviations were thoroughly commented on.

Influence of low-intensity variable magnetic field with proton magnetic resonance frequency of morfin and lidocain on rats nociception

Influence of low-intensity variable magnetic field with proton magnetic resonance frequency of morfin and lidocain on rats nociception

Influence of low-intensity variable magnetic field with proton magnetic resonance spectrum frequencies of dopamine to development of a conditioned defensive reflex of gastropods

Influence of low-intensity variable magnetic field with proton magnetic resonance spectrum frequencies of dopamine to development of a conditioned defensive reflex of gastropods

Polymeric microellipsoids with programmed magnetic anisotropy for controlled rotation using low (≈10 mT) magnetic fields

Polymeric magnetic spherical microparticles are employed as sensors/actuators in lab-on-a-chip applications, small-scale robotics and biomedical/biophysical assays. Achieving controlled stable motion of the microparticles in a fluid environment using low intensity magnetic fields is necessary to achieve much of their technological potential; this requires that the microparticle is magnetically anisotropic, which is difficult to achieve in spheres. Here we have developed a simple method to synthesise anisotropic ellipsoidal microparticles (average eccentricity 0.60 ± 0.14) by applying a magnetic field during synthesis, using a nanocomposite of polycaprolactone (PCL) with Fe3O4 nanowires. The “microellipsoids” are thoroughly characterised using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Their suitability for magnetically controlled motion is demonstrated by analysing their rotation in low magnetic fields (0.1, 1, 5, 10 and 20 mT) at varying rotational frequencies (1 Hz and 5 Hz). The microellipsoids are able to follow smoothly and continuously the magnetic field, while commercial spherical particles fail to continuously follow the magnetic field, and oscillate backwards and forwards resulting in much lower average angular speeds. Furthermore, only 23 % of commercial particles analysed rotated at 1 Hz and 26 % at 5 Hz, whereas 77 % of our ellipsoidal particles rotated at 1 Hz, and 74 % did at 5 Hz.

Weighted iterative inversion method for T2 spectrum in nuclear magnetic resonance

In traditional nuclear magnetic resonance T2 inversion methods, the components with long T2 absorb the components with short T2, especially for low magnetic field intensity. As a result, the true distribution of all components often cannot be reflected by their solutions, and thus obtaining short T2 components is an important T2 inversion problem. Herein, a weighted iterative inversion method for T2 spectrum in nuclear magnetic resonance is proposed to solve this problem. The weight-based method is applied to ensure that the short T2 components are not eliminated. The weight scheme is determined by two parameters: the number of weights and maximum weight. The number of weights is determined by the rate of decay, and the maximum weight is mainly determined by three parameters: signal-noise ratio, curvature, and slope of collected signal. To avoid the mutations of results caused by weights, the iteration process was adopted to obtain the optimal solution. The proposed method provides good results, and it was verified to be robust and accurate though simulations and experiments.

Characterisation of spectroscopic and magneto-optical faraday rotation in Mn2+- doped CdS quantum dots in a silicate glass

We demonstrate the control of CdS and Mn2+-doped-CdS Q-dots in a silicate glass for magneto-optical applications. The microstructural properties of Q-dot glasses were investigated by X-Ray diffraction (XRD), Field Emission Transmission Electron Microscopy (FETEM) and the optical properties by UV–Visible–NIR and Photoluminescence (PL) spectroscopic techniques, respectively. The FETEM of the CdS QD–glass heat treated at 600oC reveals that the size of CdS and Mn2+-doped CdS Q-dots are in the range of 4-5 nm and 5-6 nm, respectively. The observed size distributions of Q-dots were in reasonable agreement with the data, derived from X-ray line broadening and estimated average Bohr radii using the UV–visible absorption data. Photoluminescence characteristics were investigated at room temperature by exciting the CdS and Mn2+-doped-CdS Q-dot glasses with a 420 nm excitation source, which yielded broad emission spectra in the visible and near-IR range (450-800 nm). We observed a red shift in the emission peak with increase in the Q-dot size, controlled by heat treatment temperature range (550-600oC). The room-temperature magneto-optical Faraday rotation measurements on Q-dots glasses were carried out using magnetic field strength up to 360 mT, and observed an increase in the value of Verdet constant, from 6.2 to 12.0°/T-cm, when comparing undoped CdS-Q-dot glass with Mn2+-doped CdS glass. The demonstration of enhanced Verdet constant in Q-dot silicate glasses with sub-Tesla field paves the path for engineering range magneto-optical devices for photonics, spintronics and sensors applications, in which the polarization of photons may be controlled with low-intensity magnetic field in optical waveguides.