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Transcranial Magnetic Stimulation is an emerging non-invasive treatment for depression, Parkinson's disease, and a variety of other neurological disorders. Many Parkinson's patients receive the treatment known as Deep Brain Stimulation, but often require additional therapy for speech and swallowing impairment. Transcranial Magnetic Stimulation has been explored as a possible treatment by stimulating the mouth motor area of the brain. We have calculated induced electric field, magnetic field, and temperature distributions in the brain using finite element analysis and anatomically realistic heterogeneous head models fitted with Deep Brain Stimulation leads. A Figure of 8 coil, current of 5000 A, and frequency of 2.5 kHz are used as simulation parameters. Results suggest that Deep Brain Stimulation leads cause surrounding tissues to experience slightly increased E-field (ΔEmax = 30 V/m), but not exceeding the nominal values induced in brain tissue by Transcranial Magnetic Stimulation without leads (215 V/m). The maximum temperature in the brain tissues surrounding leads did not change significantly from the normal human body temperature of 37 °C. Therefore, we ascertain that Transcranial Magnetic Stimulation in the mouth motor area may stimulate brain tissue surrounding Deep Brain Stimulation leads, but will not cause tissue damage. [ABSTRACT FROM AUTHOR]

Transcranial Magnetic Stimulation (TMS) is a technique for neuromodulation that can be used as a non-invasive therapy for various neurological disorders. In TMS, a time varying magnetic field generated from an electromagnetic coil placed on the scalp is used to induce an electric field inside the brain. TMS coil geometry plays an important role in determining the focality and depth of penetration of the induced electric field responsible for stimulation. Clinicians and basic scientists are interested in stimulating a localized area of the brain, while minimizing the stimulation of surrounding neural networks. In this paper, a novel coil has been proposed, namely Quadruple Butterfly Coil (QBC) with an improved focality over the commercial Figure-8 coil. Finite element simulations were conducted with both the QBC and the conventional Figure-8 coil. The two coil's stimulation profiles were assessed with 50 anatomically realistic MRI derived head models. The coils were positioned on the vertex and the scalp over the dorsolateral prefrontal cortex to stimulate the brain. Computer modeling of the coils has been done to determine the parameters of interest-volume of stimulation, maximum electric field, location of maximum electric field and area of stimulation across all 50 head models for both coils. [ABSTRACT FROM AUTHOR]

Hall-effect (HE) sensors based on high-quality Mn-doped Bi2Te3 topological insulator (TI) thin films have been systematically studied in this paper. Improvement of Hall sensitivity is found after doping the magnetic element Mn into Bi2Te3. The sensors with low Mn concentrations, MnxBi2−xTe3, $x =0.01$ and 0.08 show the linear behavior of Hall resistance with sensitivity about 5 $\Omega $ /T. And their Hall sensitivity shows weak dependence on temperature. For sensors with high Mn concentration ( $x=0.23$ ), the Hall resistance with respect to magnetic field shows a hysteretic behavior. Moreover, its sensitivity shows almost eight times as high as that of the HE sensors with low Mn concentration. The highest sensitivity can reach 43 $\Omega $ /T at very low magnetic field. This increase of Hall sensitivity is caused by the occurrence of anomalous HE (AHE) after ferromagnetic phase transition. Our work indicates that the magnetic-element-doped TIs with AHE are good candidates for HE sensors. [ABSTRACT FROM AUTHOR]

Abstract–Gd5{(Six{\rm Ge}1-{\rm x})}4 exhibits a first order phase transition for the compositions 0

Copyright of Journal of Textiles & Engineers / Tekstil ve Mühendis is the property of Union of Chambers of Turkish Engineers & Architects, Chamber of Textile Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gd5(SixGe1-x)4 exhibits anomalous behavior in resistivity measurement close to its first-order phase transition temperature. In this paper, we present a series of resistivity as a function of temperature measurements indicating an irreversible change in the resistivity. The resistivity of the sample increased every time the sample was passed through first-order phase transition for both single-crystal Gd5 Si1.8 Ge2.2 (x = 0.45) and polycrystalline Gd5 Si2.09 Ge1.91 (x = 0.522). Magnetic hysteresis loops were also plotted for the single-crystal Gd5Si1.8 Ge2.2 at 220 K. The hysteresis loops were measured several times at 220 K, cycling the temperature between 220 and 300 K between each measurement. The coercivity of the sample increased irreversibly when the sample was passed through the first-order phase transition. The increase in the coercivity was 20 Oe for the fourth and fifth thermal cycles and then it remained constant up to 15 thermal cycles. [ABSTRACT FROM AUTHOR]

Gd5(SixGe1-x)4 exhibits anomalous behavior in resistivity measurement close to its first-order phase transition temperature. In this paper, we present a series of resistivity as a function of temperature measurements indicating an irreversible change in the resistivity. The resistivity of the sample increased every time the sample was passed through first-order phase transition for both single-crystal Gd5 Si1.8 Ge2.2 (x = 0.45) and polycrystalline Gd5 Si2.09 Ge1.91 (x = 0.522). Magnetic hysteresis loops were also plotted for the single-crystal Gd5Si1.8 Ge2.2 at 220 K. The hysteresis loops were measured several times at 220 K, cycling the temperature between 220 and 300 K between each measurement. The coercivity of the sample increased irreversibly when the sample was passed through the first-order phase transition. The increase in the coercivity was 20 Oe for the fourth and fifth thermal cycles and then it remained constant up to 15 thermal cycles. [ABSTRACT FROM AUTHOR]

We report for the first time successful growth of magnetic thin films containing the Gd5(SixGe1-x)4 phase, which is expected to show giant magnetocaloric properties. The film was deposited by Pulsed Laser Deposition (PLD) on a (001) silicon wafer at 200 °C from a polycrystalline Gd5Si2.09Ge1.91 target prepared by arc melting. PLD was achieved using a femto second laser with a repetition rate of 1 kHz, and a pulse energy of up to 3.5 mJ. The average film thickness was measured to be 400 nm using a Scanning Electron Microscopy and the composition of the film was analyzed using Energy Dispersive Spectroscopy and found to be close to the target composition. X-Ray Diffraction analysis confirmed the presence of Gd5Si2Ge2 monoclinic structure. Magnetic moment vs. magnetic field measurement confirmed that the film was ferromagnetic at a temperature of 200 K. The transition temperature of the film was determined from a plot of magnetic moment vs. temperature. The transition temperature was between 280 and 300 K which is close to the transition temperature of the bulk material. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) is a non-invasive technique for diagnosis and treatment of various neurological conditions. However, the lack of realistic physical models to test the safety and efficacy of stimulation from magnetic fields generated by the coils has hindered the development of new TMS treatment and diagnosis protocols for several neurological conditions. We have developed an anatomically and geometrically accurate brain and head phantom with an adjustable electrical conductivity matching the average conductivity of white matter and grey matter of the human brain and the cerebrospinal fluid. The process of producing the phantom starts with segmenting the MRI images of the brain and then creating shells from the segmented and reconstructed model ready for 3-D printing and serving as a mold for the conductive polymer. Furthermore, we present SEM images and conductivity measurements of the conductive polymer composite as well as confirmation of the anatomical accuracy of the phantom with computed tomography (CT) images. Finally, we show the results of induced voltage measurements obtained from TMS on the brain phantom., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A multi-functional Gd 5 Si 1.3 Ge 2.7 thin film deposited by pulsed laser ablation in the form of an ensemble of nanoparticles was studied for 18 thermal cycles via electron transport measurements together with structural and magnetic characterization. A general negative thermal dependency of the resistivity (ρ) is observed, which contrasts with the metallic-like behavior observed in bulk Gd 5 Si x Ge 4-x compounds. This general trend is interrupted by a two-step, positive-slope transition in ρ(T) throughout the [150, 250] K interval, corresponding to two consecutive magnetic transitions: a fully coupled magnetostructural followed by a magnetic order on heating. An avalanche-like behavior is unveiled by the ∂ρ/∂T(T) curves and is explained based on the severe strains induced cyclically by the magnetostructural transition, leading to a cycling evolution of the transition onset temperature ([Formula: see text]/∂n ∼ 1.6 K/cycle, n being the number of cycles). Such behavior is equivalent to the action of a pressure of 0.56 kBar being formed and building up at every thermal cycle due to the large volume induced change across the magnetostructural transition. Moreover the thermal hysteresis, detected in both ρ and magnetization versus temperature curves, evolves significantly along the cycles, decreasing as n increases. This picture corroborates the thermal activation energy enhancement-estimated via an exponential fitting of the ∂ρ/∂T(T) in the avalanche regime. This work demonstrates the importance of using a short-range order technique, to probe both magnetic and magnetostructural transitions and their evolution with thermal cycles.