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Applied Magnetic Resonance

A J Barakat, L Pel, O C G Adan
In this study a specialized high-temperature nuclear magnetic resonance (NMR) setup is presented for measuring free moisture in monolithic refractory castables during one-sided heating (100-300 °C). This setup makes use of a high thermal-stability Birdcage-coil for measuring the quantitative moisture content at high-temperatures, while also utilizing a mini-coil for calibrating transverse relaxation changes, as a function of temperature and hydration state, taking place in the sample throughout a drying experiment...
2018: Applied Magnetic Resonance
Carlos Cabal Mirabal, Adolfo Fernández García, Manuel Lores Guevara, Evelio González, Leonardo Oramas Díaz
The potentials of the magnetic resonance (MR) methods in the research of biomedical systems have been demonstrated during the 70 years of its existence. It is presented that the Cuban experience in quantitative magnetic resonance associated with molecular, preclinical and clinical studies of significant diseases and drugs development. MR "in vitro" and "in vivo" studies of sickle cell disease, the diabetic foot ulcer, the brain tumor response and the magnetic nano-particle pharmacokinetics, are presented as example...
2018: Applied Magnetic Resonance
M Cifelli, V Domenici, V I Chizhik, S V Dvinskikh
Unique combination of ionic conductivity and anisotropic physical properties in ionic liquid crystals leads to new dynamic properties exploited in modern technological applications. Structural and dynamics information at atomic level for molecules and ions in mesophases can be obtained by nuclear magnetic resonance (NMR) spectroscopy through the measurements of dipole-dipole spin couplings. While 13 C-1 H and 15 N-1 H dipolar NMR spectra can be routinely acquired in samples with natural isotopic abundance, recording 15 N-13 C dipolar NMR spectra is challenging because of the unfavourable combination of two rare isotopes...
2018: Applied Magnetic Resonance
Archie Cable, Eteri Svanidze, Jessica Santiago, Emilia Morosan, Jörg Sichelschmidt
The electron spin resonance (ESR) of conduction electrons is reported for the weak itinerant ferromagnet Sc[Formula: see text]In which, upon chemical substitution with Lu, shows a suppression of ferromagnetic correlations. A well-defined ESR lineshape of Dysonian type characterizes the spectra. The ESR linewidth, determined by the spin dynamics, displays a broad minimum only for the Sc[Formula: see text]In compound. We discuss the results using the mechanism of exchange enhancement of spin-lifetimes.
2018: Applied Magnetic Resonance
Kelsey Meinerz, Scott C Beeman, Chong Duan, G Larry Bretthorst, Joel R Garbow, Joseph J H Ackerman
Recently, a number of MRI protocols have been reported that seek to exploit the effect of dissolved oxygen (O2 , paramagnetic) on the longitudinal 1 H relaxation of tissue water, thus providing image contrast related to tissue oxygen content. However, tissue water relaxation is dependent on a number of mechanisms, and this raises the issue of how best to model the relaxation data. This problem, the model selection problem, occurs in many branches of science and is optimally addressed by Bayesian probability theory...
January 2018: Applied Magnetic Resonance
Kirill F Sheberstov, Hans-Martin Vieth, Herbert Zimmermann, Konstantin L Ivanov, Alexey S Kiryutin, Alexandra V Yurkovskaya
We provide a detailed evaluation of nuclear magnetic resonance (NMR) parameters of the cis - and trans -isomers of azobenzene (AB). For determining the NMR parameters, such as proton-proton and proton-nitrogen J -couplings and chemical shifts, we compared NMR spectra of three different isotopomers of AB: the doubly 15 N labeled azobenzene, 15 N,15 N'-AB, and two partially deuterated AB isotopomers with a single 15 N atom. For the total lineshape analysis of NMR spectra, we used the recently developed ANATOLIA software package...
2018: Applied Magnetic Resonance
A M Panich, N A Sergeev
We developed an approach for determining distances between carbon nanoparticles and grafted paramagnetic ions and molecules by means of nuclear spin-lattice relaxation data. The approach was applied to copper-, cobalt- and gadolinium-grafted nanodiamonds, iron-grafted graphenes, manganese-grafted graphene oxide and activated carbon fibers that adsorb paramagnetic oxygen molecules. Our findings show that the aforementioned distances vary in the range of 2.7-5.4 Å and that the fixation of paramagnetic ions to nanoparticles is most likely implemented by means of the surface functional groups...
2018: Applied Magnetic Resonance
E Nikolskaya, Y Hiltunen
Average carbon chain length is a key parameter that defines the quality of liquid biofuels. In this paper, a method for the determination of carbon chain lengths of fatty acid mixtures is presented. The approach is based on proton relaxation rates measured by time domain nuclear magnetic resonance. The spin-spin relaxation rates R 2 were used for the estimation of the carbon chain lengths. The method was examined for the set of samples with different mean lengths of the main linear carbon chain. Samples were prepared using four different fatty acids and mixtures of two, three or four of these fatty acids...
2018: Applied Magnetic Resonance
Derek Marsh
Calibrations are given to extract orientation order parameters from pseudo-powder electron paramagnetic resonance line shapes of 14N-nitroxide spin labels undergoing slow rotational diffusion. The nitroxide z-axis is assumed parallel to the long molecular axis. Stochastic-Liouville simulations of slow-motion 9.4-GHz spectra for molecular ordering with a Maier-Saupe orientation potential reveal a linear dependence of the splittings, [Formula: see text] and [Formula: see text], of the outer and inner peaks on order parameter [Formula: see text] that depends on the diffusion coefficient [Formula: see text] which characterizes fluctuations of the long molecular axis...
2018: Applied Magnetic Resonance
James S Hyde
The papers, book chapters, reviews, and patents by James S. Hyde in the bibliography of this document have been separated into EPR and MRI sections, and within each section by topics. Within each topic, publications are listed chronologically. A brief summary is provided for each patent listed. A few publications and patents that do not fit this schema have been omitted. This list of publications is preceded by a scientific autobiography that focuses on selected topics that are judged to have been of most scientific importance...
December 2017: Applied Magnetic Resonance
Laxman Mainali, Theodore G Camenisch, James S Hyde, Witold K Subczynski
The presence of integral membrane proteins induces the formation of distinct domains in the lipid bilayer portion of biological membranes. Qualitative application of both continuous wave (CW) and saturation recovery (SR) electron paramagnetic resonance (EPR) spin-labeling methods allowed discrimination of the bulk, boundary, and trapped lipid domains. A recently developed method, which is based on the CW EPR spectra of phospholipid (PL) and cholesterol (Chol) analog spin labels, allows evaluation of the relative amount of PLs (% of total PLs) in the boundary plus trapped lipid domain and the relative amount of Chol (% of total Chol) in the trapped lipid domain [ M...
December 2017: Applied Magnetic Resonance
George A Rinard, Richard W Quine, Laura A Buchanan, Sandra S Eaton, Gareth R Eaton, Boris Epel, Subramanian V Sundramoorthy, Howard J Halpern
Resonators for preclinical electron paramagnetic resonance imaging have been designed primarily for rodents and rabbits and have internal diameters between 16 and 51 mm. Lumped circuit resonators include loop-gap, Alderman-Grant, and saddle coil topologies and surface coils. Bimodal resonators are useful for isolating the detected signal from incident power and reducing dead time in pulse experiments. Resonators for continuous wave, rapid scan, and pulse experiments are described. Experience at the University of Chicago and University of Denver in design of resonators for in vivo imaging is summarized...
December 2017: Applied Magnetic Resonance
Kathryn M Schultz, Candice S Klug
The use of pressure is an advantageous approach to the study of protein structure and dynamics because it can shift the equilibrium populations of protein conformations toward higher energy states that are not of sufficient population to be observable at atmospheric pressure. Recently, the Hubbell group at the University of California, Los Angeles, reintroduced the application of high pressure to the study of proteins by electron paramagnetic resonance (EPR) spectroscopy. This methodology is possible using X-band EPR spectroscopy due to advances in pressure intensifiers, sample cells, and resonators...
December 2017: Applied Magnetic Resonance
James S Hyde, Richard R Mett
The dielectric tube resonator (DTR) for EPR spectroscopy is introduced. It is defined as a metallic cylindrical TE011 microwave cavity that contains a dielectric tube centered on the axis of the cylinder. Contour plots of dimensions of the metallic cylinder to achieve resonance at 9.5 GHz are shown for quartz, sapphire, and rutile tubes as a function of wall thickness and average radius. These contour plots were developed using analytical equations and confirmed by finite element modeling. They can be used in two ways: design of the metallic cylinder for use at 9...
December 2017: Applied Magnetic Resonance
George A Rinard, Richard W Quine, Joseph McPeak, Laura Buchanan, Sandra S Eaton, Gareth R Eaton
A copper X-band (9.22 GHz) cross loop resonator has been constructed for use with 4 mm sample tubes. The Q for the two resonators are 380 and 350, respectively. The resonator efficiency is about 1 G per square root of watt. Operation has been demonstrated with measurement of T1 by saturation recovery for samples of coal and an immobilized nitroxide radical.
December 2017: Applied Magnetic Resonance
Subramanian V Sundramoorthy, Boris Epel, Howard J Halpern
A magnetometer designed for permanent magnet manufacturing and operated around 25 mT with 10ppm absolute accuracy is described. The magnetometer uses pulse electron paramagnetic resonance (EPR) methodology. The use of a pulsed broadband acquisition allowed reliable measurements in the presence of the magnetic field gradient and in relatively inhomogeneous magnetic fields of un-shimmed magnets.
August 2017: Applied Magnetic Resonance
Barney L Bales, Miroslav Peric
The behavior of Electron paramagnetic resonance spectra due to 15 N and 14 N nitroxide free radicals undergoing spin exchange in liquids at high frequencies ωex , of the same order of magnitude as the nitrogen hyperfine coupling constant A 0 is investigated. The well known features are reconfirmed: (1) at low values of ωex where the lines broaden, shift toward the center of the spectrum, and change shape due to the introduction of a resonance of the form of a dispersion component; (2) at values of ωex comparable to A 0 , the line merge into one; and (3) at values much larger than A 0 , the merged line narrows...
February 2017: Applied Magnetic Resonance
Jason W Sidabras, Edward J Reijerse, Wolfgang Lubitz
Uniform field (UF) resonators create a region-of-interest, where the sample volume receives a homogeneous microwave magnetic field ([Formula: see text]) excitation. However, as the region-of-interest is increased, resonator efficiency is reduced. In this work, a new class of uniform field resonators is introduced: the uniform field re-entrant cylindrical TE[Formula: see text] cavity. Here, a UF cylindrical TE[Formula: see text] cavity is designed with re-entrant fins to increase the overall resonator efficiency to match the resonator efficiency maximum of a typical cylindrical TE[Formula: see text] cavity...
2017: Applied Magnetic Resonance
Klaus Möbius, Wolfgang Lubitz, Anton Savitsky
In this minireview, we report on our year-long EPR work, such as electron-nuclear double resonance (ENDOR), pulse electron double resonance (PELDOR) and ELDOR-detected NMR (EDNMR) at X-band and W-band microwave frequencies and magnetic fields. This report is dedicated to James S. Hyde and honors his pioneering contributions to the measurement of spin interactions in large (bio)molecules. From these interactions, detailed information is revealed on structure and dynamics of macromolecules embedded in liquid-solution or solid-state environments...
2017: Applied Magnetic Resonance
N A Sergeev, M Paczwa, M Olszewski, A M Panich
Temperature dependencies of (27)Al and (23)Na nuclear magnetic resonance spectra and spin-lattice relaxations in mordenite have been studied in static and magic angle spinning regimes. Our data show that the spin-lattice relaxations of the (23)Na and (27)Al nuclei are mainly governed by interaction of nuclear quadrupole moments with electric field gradients of the crystal, modulated by translational motion of water molecules in the mordenite channels. At temperatures below 200 K, the dipolar interaction of nuclear spins with paramagnetic impurities becomes an important relaxation mechanism of the (23)Na and (27)Al nuclei...
2017: Applied Magnetic Resonance
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