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Magnetic field

Daniel Laidig, Thomas Schauer, Thomas Seel
Inertial Measurement Units (IMUs) have become a widely used tool for rehabilitation and other application domains in which human motion is analyzed using an ambulatory or wearable setup. Since the magnetic field is inhomogeneous in indoor environments and in the proximity of ferromagnetic material, standard orientation estimation and joint angle calculation algorithms often lead to inaccurate or even completely wrong results. One approach to circumvent this is to exploit the kinematic constraint that is induced by mechanical hinge joints and also by approximate hinge joints such as the knee joint and the finger (interphalangeal) joints of the human body...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
Xu Xue, Ziyao Zhou, Guohua Dong, Mengmeng Feng, Yijun Zhang, Shishun Zhao, Zhongqiang Hu, Wei Ren, Zuo-Guang Ye, Yaohua Liu, Ming Liu
Electric field control of dynamic spin interactions is promising to break through the limitation of magnetostatic interaction based magnetoelectric (ME) effect. In this work, electric field control of two-magnon scattering (TMS) effect excited by in-plane lattice rotation has been demonstrated in La0.7Sr0.3MnO3 (LSMO)/Pb(Mn2/3Nb1/3)-PbTiO3 (PMN-PT) (011) multiferroic heterostructure. Compared with the conventional strain-mediated ME effect, a giant enhancement of ME effect up to 950% at the TMS critical angle is precisely determined by angular resolution of the ferromagnetic resonance (FMR) measurement...
August 16, 2017: ACS Nano
Nils Spengler, Peter T While, Markus V Meissner, Ulrike Wallrabe, Jan G Korvink
A high NMR detection sensitivity is indispensable when dealing with mass and volume-limited samples, or whenever a high spatial resolution is required. The use of miniaturised RF coils is a proven way to increase sensitivity, but situations may arise where space restrictions could prevent the use of a small resonant coil, e.g., in the interior of the smallest practicable micro-coils. We present the use of magnetic lenses, denoted as Lenz lenses due to their working principle, to focus the magnetic flux of an RF coil into a smaller volume and thereby locally enhance the sensitivity of the NMR experiment-at the expense of the total sensitive volume...
2017: PloS One
Shahab Boroun, Faïçal Larachi
This study investigates the response of magnetic nanoparticles (MNPs), dispersed in a viscoelastic hydrogel, to an external rotating magnetic field (RMF) for the purpose of developing a new class of magneto-responsive materials with tunable mass transport properties. Ferrogels were prepared by chemical cross-linking and polymerization of acrylamide in colloidal dispersions of thermally blocked MNPs of cobalt ferrite. Magnetization measurements of ferrogels in a swollen state revealed a transitional state from ferromagnetism to superparamagnetism through the shrinkage of hysteresis loops and the reduction of remanent magnetization...
August 16, 2017: Soft Matter
Jun-Li Wang, Qiang Liu, Yin-Shan Meng, Hui Zheng, Hai-Lang Zhu, Quan Shi, Tao Liu
The existence of a correlation between spin crossover and dielectric properties is a hot topic in the field of multiresponse materials, which has potential applications in the memory devices, switches, and sensors. One formidable challenge is the simultaneous and rapid on/off switching of spin states of the spin carriers and magnetic coupling between them, which is crucial for both reversible photomagnetic behavior and variations in dielectric properties. Here, we report a dinuclear Fe(II) spin crossover complex, wherein each Fe(II) center exhibits an interconversion between Fe(II)HS (HS = high-spin) and Fe(II)LS (LS = low-spin) achieved upon heating and cooling...
August 16, 2017: Inorganic Chemistry
Qiang Wu, Chaoyu Yang, Guangli Liu, Wanghuai Xu, Zhiqiang Zhu, Ting Si, Ronald X Xu
We propose a simple but efficient multiplex coaxial flow focusing (MCFF) process for single-step fabrication of multicompartment Janus microcapsules (MJMs) in a wide range of operating parameters. The produced MJMs consist of a multicompartmental core-shell structure with material compositions tunable in individual shell and core compartments. Potential applications of such a MJM agent are demonstrated in both benchtop and in vitro experiments. For the benchtop experiment, magnetic nanoparticles are loaded into one of the shell compartments and photopolymerized under ultraviolet light for controlled alignment and rotation of the microcapsules in a magnetic field...
August 16, 2017: Lab on a Chip
Ioannis-Angelos Giapitzakis, Tingting Shao, Nikolai Avdievich, Ralf Mekle, Roland Kreis, Anke Henning
PURPOSE: Metabolite cycling (MC) is an MRS technique for the simultaneous acquisition of water and metabolite spectra that avoids chemical exchange saturation transfer effects and for which water may serve as a reference signal or contain additional information in functional or diffusion studies. Here, MC was developed for human investigations at ultrahigh field. METHODS: MC-STEAM and MC-semi-LASER are introduced at 9.4T with an optimized inversion pulse and elaborate coil setup...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Jinbang Guo, Xuefeng Cao, Zackary I Cleveland, Jason C Woods
PURPOSE: To measure the T2* and T1 of mouse lung at 7T via anisotropic-resolution radial ultrashort echo-time imaging with ellipsoidal k-space coverage. METHODS: Ellipsoidal field-of-view was created by expanding uniform spherical k-space coverage. The effects of T2* and ellipsoidal sampling on image resolution were investigated by using point-spread-function analysis and resolution phantoms. Finally, this ellipsoidal sampling approach was used to measure the lung T2* and T1 of healthy C57BL/6 mice at the increasingly common preclinical field strength of 7T...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Maxime Yon, Vincent Sarou-Kanian, Ulrich Scheler, Jean-Michel Bouler, Bruno Bujoli, Dominique Massiot, Franck Fayon
In this work, we show that it is possible to overcome the limitations of solid-state MRI for rigid tissues due to large line broadening and short dephasing times by combining Magic Angle Spinning (MAS) with rotating pulsed field gradients. This allows recording ex vivo (31)P 3D and 2D slice-selected images of rigid tissues and related biomaterials at very high magnetic field, with greatly improved signal to noise ratio and spatial resolution when compared to static conditions. Cross-polarization is employed to enhance contrast and to further depict spatially localized chemical variations in reduced experimental time...
August 15, 2017: Scientific Reports
B Koteswararao, Tanmoy Chakrabarty, Tathamay Basu, Binoy Krishna Hazra, P V Srinivasarao, P L Paulose, S Srinath
We report the magnetic and dielectric behavior of Pb6Ni9(TeO6)5, a new compound comprising the honeycomb-like layers of S = 1 spins, through detailed structural, magnetic and dielectric investigation. An antiferromagnetic-type transition at 25 K (T N ) with weak-ferromagnetic behavior is revealed. Interestingly, a large value of coercive field of 1.32 T at 2 K is observed. The isothermal magnetization after zero-field-cooled condition, it exhibits the presence of large spontaneous exchange bias (SEB) with a magnitude of 0...
August 15, 2017: Scientific Reports
Yu-Cheng Shao, L Andrew Wray, Shih-Wen Huang, Yi-Sheng Liu, Wang Song, Shangfeng Yang, Yi-De Chuang, Jinghua Guo, Way-Faung Pong
Endohedral metallofullerenes, formed by encaging Gd inside fullerenes like C80, can exhibit enhanced proton relaxitivities compared with other Gd-chelates, making them the promising contrast agents for magnetic resonance imaging (MRI). However, the underlying key energy scales of Gd x Sc3-x N@C80 (x  =  1-3) remain unclear. Here, we carry out resonant inelastic x-ray scattering (RIXS) experiments on Gd x Sc3-x N@C80 at Gd N 4,5-edges to directly study the electronic structure and spin flip excitations of Gd 4f electrons...
August 15, 2017: Scientific Reports
Mikkel Østergaard, Charles G Peterfy, Paul Bird, Frédérique Gandjbakhch, Daniel Glinatsi, Iris Eshed, Espen A Haavardsholm, Siri Lillegraven, Pernille Bøyesen, Bo Ejbjerg, Violaine Foltz, Paul Emery, Harry K Genant, Philip G Conaghan
OBJECTIVE: The Outcome Measures in Rheumatology (OMERACT) Rheumatoid Arthritis (RA) Magnetic Resonance Imaging (MRI) scoring system (RAMRIS), evaluating bone erosion, bone marrow edema/osteitis, and synovitis, was introduced in 2002, and is now the standard method of objectively quantifying inflammation and damage by MRI in RA trials. The objective of this paper was to identify subsequent advances and based on them, to provide updated recommendations for the RAMRIS. METHODS: MRI studies relevant for RAMRIS and technical and scientific advances were analyzed by the OMERACT MRI in Arthritis Working Group, which used these data to provide updated considerations on image acquisition, RAMRIS definitions, and scoring systems for the original and new RA pathologies...
August 15, 2017: Journal of Rheumatology
Bruna Ferreira Gomes, Pollyana Ferreira da Silva, Carlos Manuel Silva Lobo, Maiara da Silva Santos, Luiz Alberto Colnago
The strong effect of magnetic field on the electrochemical (EC) reduction of a diamagnetic species was monitored in situ in a 600 MHz (14 T) NMR spectrometer. Throughout EC-NMR experiments, the diamagnetic species is influenced by the Lorentz force (cross product of current density and magnetic field), which in turn acts on analyte transport and, as a result, enhances reaction rates. This phenomenon, known as magnetoelectrolysis, has not been considered in several in situ EC-NMR studies in solution, electron paramagnetic resonance (EC-EPR) spectroscopy, and magnetic resonance imaging (EC-MRI) involving the oxidation and reduction of organic compounds and lithium ion batteries...
August 29, 2017: Analytica Chimica Acta
Alberto Chisvert, Juan L Benedé, Jared L Anderson, Stephen A Pierson, Amparo Salvador
With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism)...
August 29, 2017: Analytica Chimica Acta
Thomas P Fay, Alan M Lewis, David E Manolopoulos
We have used an efficient new quantum mechanical method for radical pair recombination reactions to study the spin-dependent charge recombination along PTZ(•+)-Phn-PDI(•-) molecular wires. By comparing our results with the experimental data of Weiss et al. [J. Am. Chem. Soc. 126, 5577 (2004)], we are able to extract the spin-dependent (singlet and triplet) charge recombination rate constants for wires with n = 2-5. These spin-dependent rate constants have not been extracted previously from the experimental data because they require fitting its magnetic field-dependence to the results of quantum spin dynamics simulations...
August 14, 2017: Journal of Chemical Physics
Wujun Zhao, Rui Cheng, Brittany D Jenkins, Taotao Zhu, Nneoma E Okonkwo, Courtney E Jones, Melissa B Davis, Sravan K Kavuri, Zhonglin Hao, Carsten Schroeder, Leidong Mao
Circulating tumor cells (CTCs) have significant implications in both basic cancer research and clinical applications. To address the limited availability of viable CTCs for fundamental and clinical investigations, effective separation of extremely rare CTCs from blood is critical. Ferrohydrodynamic cell separation (FCS), a label-free method that conducted cell sorting based on cell size difference in biocompatible ferrofluids, has thus far not been able to enrich low-concentration CTCs from cancer patients' blood because of technical challenges associated with processing clinical samples...
August 15, 2017: Lab on a Chip
N A Usov, O N Serebryakova, V P Tarasov
A specific absorption rate of a dilute assembly of various random clusters of iron oxide nanoparticles in alternating magnetic field has been calculated using Landau-Lifshitz stochastic equation. This approach simultaneously takes into account both the presence of thermal fluctuations of the nanoparticle magnetic moments and magneto-dipole interaction between the nanoparticles of the clusters. It is shown that for usual 3D clusters, the intensity of the magneto-dipole interaction is determined mainly by the cluster packing density η = N p V/V cl , where N p is the average number of the particles in the cluster, V is the nanoparticle volume, and V cl is the cluster volume...
August 14, 2017: Nanoscale Research Letters
M Emondts, J F P Colell, B Blümich, P P M Schleker
Parahydrogen induced polarization (PHIP) is a hyperpolarization method for NMR signal enhancement with applications in spectroscopy and imaging. Although parahydrogen can be easily enriched up to nearly 95%, the polarization detected on the hydrogenated substrate is substantially lower, where numerous loss mechanisms between the start of the hydrogenation reaction and detection affect polarization levels. The quality of PHIP systems is commonly determined by stating either the polarization degree or the enhancement factor of the product at the time of detection...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
Sonia M Tikoo, Benjamin P Weiss, David L Shuster, Clément Suavet, Huapei Wang, Timothy L Grove
Magnetic studies of lunar rocks indicate that the Moon generated a core dynamo with surface field intensities of ~20 to 110 μT between at least 4.25 and 3.56 billion years ago (Ga). The field subsequently declined to <~4 μT by 3.19 Ga, but it has been unclear whether the dynamo had terminated by this time or just greatly weakened in intensity. We present analyses that demonstrate that the melt glass matrix of a young regolith breccia was magnetized in a ~5 ± 2 μT dynamo field at ~1 to ~2.5 Ga. These data extend the known lifetime of the lunar dynamo by at least 1 billion years...
August 2017: Science Advances
Ankur S Narain, Fady Y Hijji, Kelly H Yom, Krishna T Kudaravalli, Brittany E Haws, Kern Singh
Intraoperative imaging is vital for accurate placement of instrumentation in spine surgery. However, the use of biplanar fluoroscopy and other intraoperative imaging modalities is associated with the risk of significant radiation exposure in the patient, surgeon, and surgical staff. Radiation exposure in the form of ionizing radiation can lead to cellular damage via the induction of DNA lesions and the production of reactive oxygen species. These effects often result in cell death or genomic instability, leading to various radiation-associated pathologies including an increased risk of malignancy...
July 18, 2017: World Journal of Orthopedics
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