Key metabolites in tissue extracts of Elliptio complanata identified using 1H nuclear magnetic resonance spectroscopy

PubMed Central

Hurley-Sanders, Jennifer L.; Levine, Jay F.; Nelson, Stacy A. C.; Law, J. M.; Showers, William J.; Stoskopf, Michael K.

2015-01-01

We used 1H nuclear magnetic resonance spectroscopy to describe key metabolites of the polar metabolome of the freshwater mussel, Elliptio complanata. Principal components analysis documented variability across tissue types and river of origin in mussels collected from two rivers in North Carolina (USA). Muscle, digestive gland, mantle and gill tissues yielded identifiable but overlapping metabolic profiles. Variation in digestive gland metabolic profiles between the two mussel collection sites was characterized by differences in mono- and disaccharides. Variation in mantle tissue metabolomes appeared to be associated with sex. Nuclear magnetic resonance spectroscopy is a sensitive means to detect metabolites in the tissues of E. complanata and holds promise as a tool for the investigation of freshwater mussel health and physiology. PMID:27293708

A magnetically focused molecular beam of ortho-water.

PubMed

Kravchuk, T; Reznikov, M; Tichonov, P; Avidor, N; Meir, Y; Bekkerman, A; Alexandrowicz, G

2011-01-21

Like dihydrogen, water exists as two spin isomers, ortho and para, with the nuclear magnetic moments of the hydrogen atoms either parallel or antiparallel. The ratio of the two spin isomers and their physical properties play an important role in a wide variety of research fields, ranging from astrophysics to nuclear magnetic resonance (NMR). Unlike ortho and para H(2), however, the two water isomers remain challenging to separate, and as a consequence, very little is currently known about their different physical properties. Here, we report the formation of a magnetically focused molecular beam of ortho-water. The beam we formed also had a particular spin projection. Thus, in the presence of holding magnetic fields, the water molecules are hyperpolarized, laying the foundation for ultrasensitive NMR experiments in the future.

Phase transition studied by 7Li nuclear magnetic resonance in LiXSO4 (X = K, Rb, Cs and NH4) single crystals

NASA Astrophysics Data System (ADS)

Lim, Ae Ran; Choh, Sung Ho; Jeong, Se-Young

2000-11-01

The temperature dependences of 7Li nuclear magnetic resonance in LiXSO4 (X = K, Rb, Cs, and NH4) single crystals grown by the slow evaporation method have been investigated by employing a Bruker FT NMR spectrometer. From the experimental data, the nuclear quadrupole constant, the asymmetry parameter and the principal axes of the EFG tensor were determined, and the results were compared with the crystal structure. The temperature dependences of the quadrupole parameters were explained with a single torsional mode of the Li-O bond by the Bayer theory. All the LiO4 tetrahedra in four different crystals showed torsional motion about the X-axis of the EFG tensor. Based on these results, the differences in atomic weight of X in the LiXSO4 single crystals are responsible for the differences in the torsional angular frequencies.

Quantification of aquifer properties with surface nuclear magnetic resonance in the Platte River valley, central Nebraska, using a novel inversion method

USGS Publications Warehouse

Irons, Trevor P.; Hobza, Christopher M.; Steele, Gregory V.; Abraham, Jared D.; Cannia, James C.; Woodward, Duane D.

2012-01-01

Surface nuclear magnetic resonance, a noninvasive geophysical method, measures a signal directly related to the amount of water in the subsurface. This allows for low-cost quantitative estimates of hydraulic parameters. In practice, however, additional factors influence the signal, complicating interpretation. The U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District, evaluated whether hydraulic parameters derived from surface nuclear magnetic resonance data could provide valuable input into groundwater models used for evaluating water-management practices. Two calibration sites in Dawson County, Nebraska, were chosen based on previous detailed hydrogeologic and geophysical investigations. At both sites, surface nuclear magnetic resonance data were collected, and derived parameters were compared with results from four constant-discharge aquifer tests previously conducted at those same sites. Additionally, borehole electromagnetic-induction flowmeter data were analyzed as a less-expensive surrogate for traditional aquifer tests. Building on recent work, a novel surface nuclear magnetic resonance modeling and inversion method was developed that incorporates electrical conductivity and effects due to magnetic-field inhomogeneities, both of which can have a substantial impact on the data. After comparing surface nuclear magnetic resonance inversions at the two calibration sites, the nuclear magnetic-resonance-derived parameters were compared with previously performed aquifer tests in the Central Platte Natural Resources District. This comparison served as a blind test for the developed method. The nuclear magnetic-resonance-derived aquifer parameters were in agreement with results of aquifer tests where the environmental noise allowed data collection and the aquifer test zones overlapped with the surface nuclear magnetic resonance testing. In some cases, the previously performed aquifer tests were not designed fully to characterize the aquifer, and the surface nuclear magnetic resonance was able to provide missing data. In favorable locations, surface nuclear magnetic resonance is able to provide valuable noninvasive information about aquifer parameters and should be a useful tool for groundwater managers in Nebraska.

The Fourier Transform in Chemistry. Part 1. Nuclear Magnetic Resonance: Introduction.

ERIC Educational Resources Information Center

King, Roy W.; Williams, Kathryn R.

1989-01-01

Using fourier transformation methods in nuclear magnetic resonance has made possible increased sensitivity in chemical analysis. This article describes these methods as they relate to magnetization, the RF magnetic field, nuclear relaxation, the RF pulse, and free induction decay. (CW)

Enantiodifferentiation through frequency-selective pure-shift (1)H nuclear magnetic resonance spectroscopy.

PubMed

Castañar, Laura; Pérez-Trujillo, Míriam; Nolis, Pau; Monteagudo, Eva; Virgili, Albert; Parella, Teodor

2014-04-04

A frequency-selective 1D (1) H nuclear magnetic resonance (NMR) experiment for the fast and sensitive determination of chemical-shift differences between overlapped resonances is proposed. The resulting fully homodecoupled (1) H NMR resonances appear as resolved 1D singlets without their typical J(HH) coupling constant multiplet structures. The high signal dispersion that is achieved is then exploited in enantiodiscrimination studies by using chiral solvating agents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neutrino Opacity in High Density Nuclear Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santos, Sergio M. dos; Razeira, Moises; Vasconcellos, Cesar A.Z.

2004-12-02

We estimate the contribution of the nucleon weak magnetism on the neutrino absorption mean free path inside high density nuclear matter. In the mean field approach, three different ingredients are taken into account: (a) a relativistic generalization of the approach developed by Sanjay et al.; (b) the inclusion of the nucleon weak-magnetism (c) and the pseudo-scalar interaction involving the nucleons. Our main result shows that the neutrino absorption mean free path is three times the corresponding result obtained by those authors.

Time-Domain Nuclear Magnetic Resonance Investigation of Water Dynamics in Different Ginger Cultivars.

PubMed

Huang, Chongyang; Zhou, Qi; Gao, Shan; Bao, Qingjia; Chen, Fang; Liu, Chaoyang

2016-01-20

Different ginger cultivars may contain different nutritional and medicinal values. In this study, a time-domain nuclear magnetic resonance method was employed to study water dynamics in different ginger cultivars. Significant differences in transverse relaxation time T2 values assigned to the distribution of water in different parts of the plant were observed between Henan ginger and four other ginger cultivars. Ion concentration and metabolic analysis showed similar differences in Mn ion concentrations and organic solutes among the different ginger cultivars, respectively. On the basis of Pearson's correlation analysis, many organic solutes and 6-gingerol, the main active substance of ginger, exhibited significant correlations with water distribution as determined by NMR T2 relaxation, suggesting that the organic solute differences may impact water distribution. Our work demonstrates that low-field NMR relaxometry provides useful information about water dynamics in different ginger cultivars as affected by the presence of different organic solutes.

Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

PubMed

Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

2016-04-07

We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed.

Wide-range nuclear magnetic resonance detector

NASA Technical Reports Server (NTRS)

Sturman, J. C.; Jirberg, R. J.

1972-01-01

Compact and easy to use solid state nuclear magnetic resonance detector is designed for measuring field strength to 20 teslas in cryogenically cooled magnets. Extremely low noise and high sensitivity make detector applicable to nearly all types of analytical nuclear magnetic resonance measurements and can be used in high temperature and radiation environments.

Rock-Magnetic Method for Post Nuclear Detonation Diagnostics

NASA Astrophysics Data System (ADS)

Englert, J.; Petrosky, J.; Bailey, W.; Watts, D. R.; Tauxe, L.; Heger, A. S.

2011-12-01

A magnetic signature characteristic of a Nuclear Electromagnetic Pulse (NEMP) may still be detectable near the sites of atmospheric nuclear tests conducted at what is now the Nevada National Security Site. This signature is due to a secondary magnetization component of the natural remanent magnetization of material containing traces of ferromagnetic particles that have been exposed to a strong pulse of magnetic field. We apply a rock-magnetic method introduced by Verrier et al. (2002), and tested on samples exposed to artificial lightning, to samples of rock and building materials (e.g. bricks, concrete) retrieved from several above ground nuclear test sites. The results of magnetization measurements are compared to NEMP simulations and historic test measurements.

Measurement of the 1s Hyperfine Transition of Two Tl^80+ Isotopes

NASA Astrophysics Data System (ADS)

Beiersdorfer, P.; Utter, S. B.; Wong, K. L.; Crespo López-Urrutia, J. R.; Britten, J. A.; Chen, H.; Thoe, R. S.; Thorn, D. B.; Träbert, E.; Gustavsson, M. G. H.; Forssén, C.; Mårtenson-Pendrill, A.-M.; Harris, C. L.

2001-05-01

The hyperfine splitting of the 1s ground state has been measured for the two stable isotopes of hydrogen-like Tl using emission spectroscopy in the SuperEBIT electron beam ion trap. The results are 3858.22± 0.30 Åfor ^203Tl^80+ and 3821.84± 0.34 Åfor ^205Tl^80+. These differ by about 60 Å from recent and about 19 Å from very recent calculations, illustrating unsolved issues affecting these transitions in hydrogen-like ions. The wavelength difference Δλ = 36.38± 0.35 Å is consistent with estimates based on hyperfine anomaly data for neutral Tl. By using previously determined nuclear magnetic moments and applying appropriate corrections for the nuclear charge distribution and radiative effects, the experimental splittings can be interpreted in terms of nuclear magnetization radii < r^2_m>^1/2= 5.83(14) fm for ^203Tl and < r^2_m>^1/2= 5.89(14) fm for ^205Tl. These values are 10% larger than derived from single-particle nuclear magnetization models, and are slightly larger than the corresponding charge distributions. *Work performed under the auspices of DOE by UCLLNL under contract W-7405-ENG-48 and supported by the Office of Basic Energy Sciences.

Status of the chiral magnetic effect and collisions of isobars

DOE PAGES

Koch, Volker; Schlichting, Soeren; Skokov, Vladimir; ...

2017-04-30

Here, we examine the current theoretical and experimental status of the chiral magnetic effect. We discuss possible future strategies for resolving uncertainties in interpretation including recommendations for theoretical work, recommendations for measurements based on data collected in the past five years, and recommendations for beam use in the coming years of RHIC. We then investigate the case for colliding nuclear isobars (nuclei with the same mass but different charge) and find the case compelling. We recommend that a program of nuclear isobar collisions to isolate the chiral magnetic effect from background sources be placed as a high priority item inmore » the strategy for completing the RHIC mission.« less

Magnetic nanoparticles in magnetic resonance imaging and diagnostics.

PubMed

Rümenapp, Christine; Gleich, Bernhard; Haase, Axel

2012-05-01

Magnetic nanoparticles are useful as contrast agents for magnetic resonance imaging (MRI). Paramagnetic contrast agents have been used for a long time, but more recently superparamagnetic iron oxide nanoparticles (SPIOs) have been discovered to influence MRI contrast as well. In contrast to paramagnetic contrast agents, SPIOs can be functionalized and size-tailored in order to adapt to various kinds of soft tissues. Although both types of contrast agents have a inducible magnetization, their mechanisms of influence on spin-spin and spin-lattice relaxation of protons are different. A special emphasis on the basic magnetism of nanoparticles and their structures as well as on the principle of nuclear magnetic resonance is made. Examples of different contrast-enhanced magnetic resonance images are given. The potential use of magnetic nanoparticles as diagnostic tracers is explored. Additionally, SPIOs can be used in diagnostic magnetic resonance, since the spin relaxation time of water protons differs, whether magnetic nanoparticles are bound to a target or not.

I. I. Rabi, Nuclear Magnetic Resonance (NMR), and Radar

Science.gov Websites

dropdown arrow Site Map A-Z Index Menu Synopsis I. I. Rabi, Nuclear Magnetic Resonance (NMR), and Radar Nobel Prize in Physics "for his resonance method for recording the magnetic properties of atomic the atomic clock, the laser and the diagnostic scanning of the human body by nuclear magnetic

Applications of Nuclear Magnetic Resonance Sensors to Cultural Heritage

PubMed Central

Proietti, Noemi; Capitani, Donatella; Di Tullio, Valeria

2014-01-01

In recent years nuclear magnetic resonance (NMR) sensors have been increasingly applied to investigate, characterize and monitor objects of cultural heritage interest. NMR is not confined to a few specific applications, but rather its use can be successfully extended to a wide number of different cultural heritage issues. A breakthrough has surely been the recent development of portable NMR sensors which can be applied in situ for non-destructive and non-invasive investigations. In this paper three studies illustrating the potential of NMR sensors in this field of research are reported. PMID:24755519

Simple and Inexpensive Classroom Demonstrations of Nuclear Magnetic Resonance and Magnetic Resonance Imaging.

ERIC Educational Resources Information Center

Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.

2000-01-01

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

NASA Astrophysics Data System (ADS)

Herlitschke, M.; Disch, S.; Sergueev, I.; Schlage, K.; Wetterskog, E.; Bergström, L.; Hermann, R. P.

2016-04-01

The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4 nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization to 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.

LIGHT-SABRE enables efficient in-magnet catalytic hyperpolarization

NASA Astrophysics Data System (ADS)

Theis, Thomas; Truong, Milton; Coffey, Aaron M.; Chekmenev, Eduard Y.; Warren, Warren S.

2014-11-01

Nuclear spin hyperpolarization overcomes the sensitivity limitations of traditional NMR and MRI, but the most general method demonstrated to date (dynamic nuclear polarization) has significant limitations in scalability, cost, and complex apparatus design. As an alternative, signal amplification by reversible exchange (SABRE) of parahydrogen on transition metal catalysts can hyperpolarize a variety of substrates, but to date this scheme has required transfer of the sample to low magnetic field or very strong RF irradiation. Here we demonstrate "Low-Irradiation Generation of High Tesla-SABRE" (LIGHT-SABRE) which works with simple pulse sequences and low power deposition; it should be usable at any magnetic field and for hyperpolarization of many different nuclei. This approach could drastically reduce the cost and complexity of producing hyperpolarized molecules.

NMR studies of field induced magnetism in CeCoIn5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graf, Matthias; Curro, Nicholas J; Young, Ben - Li

2009-01-01

Recent Nuclear Magnetic Resonance and elastic neutron scattering experiments have revealed conclusively the presence of static incommensurate magnetism in the field-induced B phase of CeCoIns, We analyze the NMR data assuming the hyperfine coupling to the 1n(2) nuclei is anisotropic and simulate the spectra for several different magnetic structures, The NMR data are consistent with ordered Ce moments along the [001] direction, but are relatively insensitive to the direction of the incommensurate wavevector.

Measurement of left ventricular mass in vivo using gated nuclear magnetic resonance imaging.

PubMed

Florentine, M S; Grosskreutz, C L; Chang, W; Hartnett, J A; Dunn, V D; Ehrhardt, J C; Fleagle, S R; Collins, S M; Marcus, M L; Skorton, D J

1986-07-01

Alterations of left ventricular mass occur in a variety of congenital and acquired heart diseases. In vivo determination of left ventricular mass, using several different techniques, has been previously reported. Problems inherent in some previous methods include the use of ionizing radiation, complicated geometric assumptions and invasive techniques. We tested the ability of gated nuclear magnetic resonance imaging to determine in vivo left ventricular mass in animals. By studying both dogs (n = 9) and cats (n = 2) of various sizes, a broad range of left ventricular mass (7 to 133 g) was examined. With a 0.5 tesla superconducting nuclear magnetic resonance imaging system the left ventricle was imaged in the transaxial plane and multiple adjacent 10 mm thick slices were obtained. Endocardial and epicardial edges were manually traced in each computer-displayed image. The wall area of each image was determined by computer and the areas were summed and multiplied by the slice thickness and the specific gravity of muscle, providing calculated left ventricular mass. Calculated left ventricular mass was compared with actual postmortem left ventricular mass using linear regression analysis. An excellent relation between calculated and actual mass was found (r = 0.95; SEE = 13.1 g; regression equation: magnetic resonance mass = 0.95 X actual mass + 14.8 g). Intraobserver and interobserver reproducibility were also excellent (r = 0.99). Thus, gated nuclear magnetic resonance imaging can accurately determine in vivo left ventricular mass in anesthetized animals.

Liquid-state nuclear spin comagnetometers.

PubMed

Ledbetter, M P; Pustelny, S; Budker, D; Romalis, M V; Blanchard, J W; Pines, A

2012-06-15

We discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and 19F nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5×10(-9)  Hz, or about 5×10(-11)  Hz in ≈1 day of integration. In a second version, spin precession of protons and 129Xe nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.

Electron-nuclear spin dynamics of Ga centers in GaAsN dilute nitride semiconductors probed by pump-probe spectroscopy

NASA Astrophysics Data System (ADS)

Sandoval-Santana, J. C.; Ibarra-Sierra, V. G.; Azaizia, S.; Carrère, H.; Bakaleinikov, L. A.; Kalevich, V. K.; Ivchenko, E. L.; Marie, X.; Amand, T.; Balocchi, A.; Kunold, A.

2018-03-01

We propose an experimental procedure to track the evolution of electronic and nuclear spins in Ga2+ centers in GaAsN dilute semiconductors. The method is based on a pump-probe scheme that enables to monitor the time evolution of the three components of the electronic and nuclear spin variables. In contrast to other characterization methods, as nuclear magnetic resonance, this one only needs moderate magnetic fields (B≈ 10 mT), and does not require microwave irradiation. Specifically, we carry out a series of tests for different experimental conditions in order to optimize the procedure for maximum sensitivity in the measurement of the circular degree of polarization. Based on previous experimental results and the theoretical calculations presented here, we estimate that the method could yield a time resolution of about 10ps.

In situ nuclear magnetic resonance microimaging of live biofilms in a microchannel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renslow, R. S.; Marshall, M. J.; Tucker, A. E.

Nuclear magnetic resonance (NMR) microimaging and spectroscopy was used to interrogate fluids of biological importance (e.g., water, buffer, medium solution) and live biofilms in a microchannel compatible for analyses at ambient pressure and under vacuum. Studies using buffer, growth medium, and actively growing Shewanella oneidensis biofilms were used to demonstrate in situ NMR microimaging measurement capabilities including velocity mapping, diffusion coefficient mapping, relaxometry, localized spectroscopy, and 2D and 3D imaging within a microchannel suitable for different analytical platforms. This technique is promising for diverse applications of correlative imaging using a portable microfluidic platform.

Collisional relaxation of MnH (X7Σ+) in a magnetic field: effect of the nuclear spin of Mn.

PubMed

Stoecklin, T; Halvick, Ph

2011-11-14

In the present study we investigate the role played by the hyperfine structure of manganese in the cooling and magnetic trapping of MnH((7)Σ(+)). The effect of the hyperfine structure of Mn on the relaxation of the magnetically trappable maximally stretched low-field seeking state of MnH((7)Σ(+)) in collisions with (3)He is deduced from comparison between the results of the present approach and our previous nuclear spin free calculations. We show that our previous results are unchanged at the temperature of the buffer gas cooling experiment but find a new resonance at very low collision energy. The role played by the different contributions to the hyperfine diatomic Hamiltonian considered in this work as well as the effect of an applied magnetic field on this resonance are also analyzed.

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

NASA Astrophysics Data System (ADS)

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-12-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10-12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets.

Efficiency of water-soluble nitroxide biradicals for dynamic nuclear polarization in rotating solids at 9.4 T: bcTol-M and cyolyl-TOTAPOL as new polarizing agents.

PubMed

Geiger, Michel; Jagtap, Anil; Kaushik, Monu; Sun, Han; Stöppler, Daniel; Sigurdsson, Snorri; Corzilius, Björn; Oschkinat, Hartmut

2018-05-09

Nitroxide biradicals are very efficient polarizing agents in magic angle spinning (MAS) cross effect (CE) dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR). Many recently synthesized, new radicals show superior DNP-efficiency in organic solvents but suffer from insufficient solubility in water or glycerol/water for biological applications. We report DNP efficiencies for two new radicals, the particularly well-water soluble bcTol-M and cyolyl-TOTAPOL, and include a comparison with three known biradicals, TOTAPOL, bcTol, and AMUPol. They differ by linker groups, featuring either a 3-aminopropane-1,2-diol or a urea tether, or by the structure of the alkyl substituents that flank the nitroxide groups. For evaluating their performances, we measured both signal enhancements  and DNP-enhanced sensitivity κ, and compared the results to electron spin relaxation data recorded at the same magnetic field strength (9.4 T). In our study, differences in DNP efficiency correlate with changes in the nuclear polarization dynamics rather than electron relaxation. The ratios of their individual ε and κ differ by up to 20%, which is explained by starkly different nuclear polarization build-up rates. For the radicals compared here empirically, using proline standard solutions, the new radical bcTol-M performs best while being most soluble in water/glycerol mixtures. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the transient response of nuclear spins in GaAs with/without nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Rasly, Mahmoud; Lin, Zhichao; Yamamoto, Masafumi; Uemura, Tetsuya

2016-05-01

As an alternative to studying the steady-state responses of nuclear spins in solid state systems, working within a transient-state framework can reveal interesting phenomena. The response of nuclear spins in GaAs to a changing magnetic field was analyzed based on the time evolution of nuclear spin temperature. Simulation results well reproduced our experimental results for the transient oblique Hanle signals observed in an all-electrical spin injection device. The analysis showed that the so called dynamic nuclear polarization can be treated as a cooling tool for the nuclear spins: It works as a provider to exchange spin angular momentum between polarized electron spins and nuclear spins through the hyperfine interaction, leading to an increase in the nuclear polarization. In addition, a time-delay of the nuclear spin temperature with a fast sweep of the external magnetic field produces a possible transient state for the nuclear spin polarization. On the other hand, the nuclear magnetic resonance acts as a heating tool for a nuclear spin system. This causes the nuclear spin temperature to jump to infinity: i.e., the average nuclear spins along with the nuclear field vanish at resonant fields of 75As, 69Ga and 71Ga, showing an interesting step-dip structure in the oblique Hanle signals. These analyses provide a quantitative understanding of nuclear spin dynamics in semiconductors for application in future computation processing.

Force-detected nuclear magnetic resonance: recent advances and future challenges.

PubMed

Poggio, M; Degen, C L

2010-08-27

We review recent efforts to detect small numbers of nuclear spins using magnetic resonance force microscopy. Magnetic resonance force microscopy (MRFM) is a scanning probe technique that relies on the mechanical measurement of the weak magnetic force between a microscopic magnet and the magnetic moments in a sample. Spurred by the recent progress in fabricating ultrasensitive force detectors, MRFM has rapidly improved its capability over the last decade. Today it boasts a spin sensitivity that surpasses conventional, inductive nuclear magnetic resonance detectors by about eight orders of magnitude. In this review we touch on the origins of this technique and focus on its recent application to nanoscale nuclear spin ensembles, in particular on the imaging of nanoscale objects with a three-dimensional (3D) spatial resolution better than 10 nm. We consider the experimental advances driving this work and highlight the underlying physical principles and limitations of the method. Finally, we discuss the challenges that must be met in order to advance the technique towards single nuclear spin sensitivity-and perhaps-to 3D microscopy of molecules with atomic resolution.

Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

DOE PAGES

Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; ...

2016-05-11

The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization tomore » 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.« less

LIGHT-SABRE enables efficient in-magnet catalytic hyperpolarization.

PubMed

Theis, Thomas; Truong, Milton; Coffey, Aaron M; Chekmenev, Eduard Y; Warren, Warren S

2014-11-01

Nuclear spin hyperpolarization overcomes the sensitivity limitations of traditional NMR and MRI, but the most general method demonstrated to date (dynamic nuclear polarization) has significant limitations in scalability, cost, and complex apparatus design. As an alternative, signal amplification by reversible exchange (SABRE) of parahydrogen on transition metal catalysts can hyperpolarize a variety of substrates, but to date this scheme has required transfer of the sample to low magnetic field or very strong RF irradiation. Here we demonstrate "Low-Irradiation Generation of High Tesla-SABRE" (LIGHT-SABRE) which works with simple pulse sequences and low power deposition; it should be usable at any magnetic field and for hyperpolarization of many different nuclei. This approach could drastically reduce the cost and complexity of producing hyperpolarized molecules. Copyright © 2014 Elsevier Inc. All rights reserved.

Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.

The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization tomore » 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.« less

Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodson, Boyd McLean

1999-12-01

Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permitmore » a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.« less

Current density tensors

NASA Astrophysics Data System (ADS)

Lazzeretti, Paolo

2018-04-01

It is shown that nonsymmetric second-rank current density tensors, related to the current densities induced by magnetic fields and nuclear magnetic dipole moments, are fundamental properties of a molecule. Together with magnetizability, nuclear magnetic shielding, and nuclear spin-spin coupling, they completely characterize its response to magnetic perturbations. Gauge invariance, resolution into isotropic, deviatoric, and antisymmetric parts, and contributions of current density tensors to magnetic properties are discussed. The components of the second-rank tensor properties are rationalized via relationships explicitly connecting them to the direction of the induced current density vectors and to the components of the current density tensors. The contribution of the deviatoric part to the average value of magnetizability, nuclear shielding, and nuclear spin-spin coupling, uniquely determined by the antisymmetric part of current density tensors, vanishes identically. The physical meaning of isotropic and anisotropic invariants of current density tensors has been investigated, and the connection between anisotropy magnitude and electron delocalization has been discussed.

Nuclear Magnetic Resonance-Based Metabolic Comparative Analysis of Two Apple Varieties with Different Resistances to Apple Scab Attacks.

PubMed

Sciubba, Fabio; Di Cocco, Maria Enrica; Gianferri, Raffaella; Capuani, Giorgio; De Salvador, Flavio Roberto; Fontanari, Marco; Gorietti, Daniela; Delfini, Maurizio

2015-09-23

Apple scab, caused by the fungus Venturia inaequalis, is the most serious disease of the apple worldwide. Two cultivars (Malus domestica), having different degrees of resistance against fungi attacks, were analyzed by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. Aqueous and organic extracts of both apple flesh and skin were studied, and over 30 metabolites, classified as organic acids, amino acids, carbohydrates, phenolic compounds, lipids, sterols, and other metabolites, were quantified by means of one-dimensional (1D) and two-dimensional (2D) NMR experiments. The metabolic profiles of the two apple cultivars were compared, and the differences were correlated with the different degrees of resistance to apple scab by means of univariate analysis. Levels of metabolites with known antifungal activity were observed not only to be higher in the Almagold cultivar but also to show different correlation patterns in comparison to Golden Delicious, implying a difference in the metabolic network involved in their biosynthesis.

Low-field nuclear magnetic resonance for the in vivo study of water content in trees

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoder, Jacob, E-mail: jlyoder@lanl.gov; Malone, Michael W.; Espy, Michelle A.

2014-09-15

Nuclear magnetic resonance (NMR) and magnetic resonance imaging have long been used to study water content in plants. Approaches have been primarily based on systems using large magnetic fields (∼1 T) to obtain NMR signals with good signal-to-noise. This is because the NMR signal scales approximately with the magnetic field strength squared. However, there are also limits to this approach in terms of realistic physiological configuration or those imposed by the size and cost of the magnet. Here we have taken a different approach – keeping the magnetic field low to produce a very light and inexpensive system, suitable formore » bulk water measurements on trees less than 5 cm in diameter, which could easily be duplicated to measure on many trees or from multiple parts of the same tree. Using this system we have shown sensitivity to water content in trees and their cuttings and observed a diurnal signal variation in tree water content in a greenhouse. We also demonstrate that, with calibration and modeling of the thermal polarization, the system is reliable under significant temperature variation.« less

Analysis of the transient response of nuclear spins in GaAs with/without nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasly, Mahmoud; Lin, Zhichao; Yamamoto, Masafumi

As an alternative to studying the steady-state responses of nuclear spins in solid state systems, working within a transient-state framework can reveal interesting phenomena. The response of nuclear spins in GaAs to a changing magnetic field was analyzed based on the time evolution of nuclear spin temperature. Simulation results well reproduced our experimental results for the transient oblique Hanle signals observed in an all-electrical spin injection device. The analysis showed that the so called dynamic nuclear polarization can be treated as a cooling tool for the nuclear spins: It works as a provider to exchange spin angular momentum between polarizedmore » electron spins and nuclear spins through the hyperfine interaction, leading to an increase in the nuclear polarization. In addition, a time-delay of the nuclear spin temperature with a fast sweep of the external magnetic field produces a possible transient state for the nuclear spin polarization. On the other hand, the nuclear magnetic resonance acts as a heating tool for a nuclear spin system. This causes the nuclear spin temperature to jump to infinity: i.e., the average nuclear spins along with the nuclear field vanish at resonant fields of {sup 75}As, {sup 69}Ga and {sup 71}Ga, showing an interesting step-dip structure in the oblique Hanle signals. These analyses provide a quantitative understanding of nuclear spin dynamics in semiconductors for application in future computation processing.« less

Structural Studies of MS2 Bacteriophage Virus Particle Disassembly by Nuclear Magnetic Resonance Relaxation Measurements

PubMed Central

Anobom, C. D.; Albuquerque, S. C.; Albernaz, F. P.; Oliveira, A. C.; Silva, J. L.; Peabody, D. S.; Valente, A. P.; Almeida, F. C. L.

2003-01-01

In this article we studied, by nuclear magnetic resonance relaxation measurements, the disassembly of a virus particle—the MS2 bacteriophage. MS2 is one of the single-stranded RNA bacteriophages that infect Escherichia coli. At pH 4.5, the phage turns to a metastable state, as is indicated by an increase in the observed nuclear magnetic resonance signal intensity upon decreasing the pH from 7.0 to 4.5. Steady-state fluorescence and circular dichroism spectra at pH 4.5 show that the difference in conformation and secondary structure is not pronounced if compared with the phage at pH 7.0. At pH 4.5, two-dimensional 15N-1H heteronuclear multiple quantum coherence (HMQC) spectrum shows ∼40 crosspeaks, corresponding to the most mobile residues of MS2 coat protein at pH 4.5. The 15N linewidth is ∼30 Hz, which is consistent with an intermediate with a rotational relaxation time of 100 ns. The average spin lattice relaxation time (T1) of the mobile residues was measured at different temperatures, clearly distinguishing between the dimer and the equilibrium intermediate. The results show, for the first time, the presence of intermediates in the process of dissociation of the MS2 bacteriophage. PMID:12770895

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

PubMed Central

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-01-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10−12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets. PMID:27910860

The design of photoelectric signal processing system for a nuclear magnetic resonance gyroscope based on FPGA

NASA Astrophysics Data System (ADS)

Zhang, Xian; Zhou, Binquan; Li, Hong; Zhao, Xinghua; Mu, Weiwei; Wu, Wenfeng

2017-10-01

Navigation technology is crucial to the national defense and military, which can realize the measurement of orientation, positioning, attitude and speed for moving object. Inertial navigation is not only autonomous, real-time, continuous, hidden, undisturbed but also no time-limited and environment-limited. The gyroscope is the core component of the inertial navigation system, whose precision and size are the bottleneck of the performance. However, nuclear magnetic resonance gyroscope is characteristic of the advantage of high precision and small size. Nuclear magnetic resonance gyroscope can meet the urgent needs of high-tech weapons and equipment development of new generation. This paper mainly designs a set of photoelectric signal processing system for nuclear magnetic resonance gyroscope based on FPGA, which process and control the information of detecting laser .The photoelectric signal with high frequency carrier is demodulated by in-phase and quadrature demodulation method. Finally, the processing system of photoelectric signal can compensate the residual magnetism of the shielding barrel and provide the information of nuclear magnetic resonance gyroscope angular velocity.

Microtesla SABRE enables 10% nitrogen-15 nuclear spin polarization.

PubMed

Theis, Thomas; Truong, Milton L; Coffey, Aaron M; Shchepin, Roman V; Waddell, Kevin W; Shi, Fan; Goodson, Boyd M; Warren, Warren S; Chekmenev, Eduard Y

2015-02-04

Parahydrogen is demonstrated to efficiently transfer its nuclear spin hyperpolarization to nitrogen-15 in pyridine and nicotinamide (vitamin B(3) amide) by conducting "signal amplification by reversible exchange" (SABRE) at microtesla fields within a magnetic shield. Following transfer of the sample from the magnetic shield chamber to a conventional NMR spectrometer, the (15)N NMR signals for these molecules are enhanced by ∼30,000- and ∼20,000-fold at 9.4 T, corresponding to ∼10% and ∼7% nuclear spin polarization, respectively. This method, dubbed "SABRE in shield enables alignment transfer to heteronuclei" or "SABRE-SHEATH", promises to be a simple, cost-effective way to hyperpolarize heteronuclei. It may be particularly useful for in vivo applications because of longer hyperpolarization lifetimes, lack of background signal, and facile chemical-shift discrimination of different species.

Microtesla SABRE Enables 10% Nitrogen-15 Nuclear Spin Polarization

PubMed Central

2016-01-01

Parahydrogen is demonstrated to efficiently transfer its nuclear spin hyperpolarization to nitrogen-15 in pyridine and nicotinamide (vitamin B3 amide) by conducting “signal amplification by reversible exchange” (SABRE) at microtesla fields within a magnetic shield. Following transfer of the sample from the magnetic shield chamber to a conventional NMR spectrometer, the 15N NMR signals for these molecules are enhanced by ∼30,000- and ∼20,000-fold at 9.4 T, corresponding to ∼10% and ∼7% nuclear spin polarization, respectively. This method, dubbed “SABRE in shield enables alignment transfer to heteronuclei” or “SABRE-SHEATH”, promises to be a simple, cost-effective way to hyperpolarize heteronuclei. It may be particularly useful for in vivo applications because of longer hyperpolarization lifetimes, lack of background signal, and facile chemical-shift discrimination of different species. PMID:25583142

The Influence of Hyperons and Strong Magnetic Field in Neutron Star Properties

NASA Astrophysics Data System (ADS)

Lopes, L. L.; Menezes, D. P.

2012-12-01

Neutron stars are among of the most exotic objects in the universe and constitute a unique laboratory to study nuclear matter above the nuclear saturation density. In this work, we study the equation of state (EoS) of the nuclear matter within a relativistic model subject to a strong magnetic field. We then apply this EoS to study and describe some of the physical characteristics of neutron stars, especially the mass-radius relation and chemical compositions. To study the influence of the magnetic field and the hyperons in the stellar interior, we consider altogether four solutions: two different magnetic field to obtain a weak and a strong influence; and two configurations: a family of neutron stars formed only by protons, electrons, and neutrons and a family formed by protons, electrons, neutrons, muons, and hyperons. The limit and the validity of the results found are discussed with some care. In all cases, the particles that constitute the neutron star are in β equilibrium and zero total net charge. Our work indicates that the effect of a strong magnetic field has to be taken into account in the description of magnetars, mainly if we believe that there are hyperons in their interior, in which case the influence of the magnetic field can increase the mass by more than 10 %. We have also seen that although a magnetar can reach 2.48 M ⊙, a natural explanation of why we do not know pulsars with masses above 2.0 M ⊙ arises. We also discuss how the magnetic field affects the strangeness fraction in some standard neutron star masses, and to conclude our paper, we revisit the direct Urca process related to the cooling of the neutron stars and show how it is affected by the hyperons and the magnetic field.

Relativistic calculation of nuclear magnetic shielding using normalized elimination of the small component

NASA Astrophysics Data System (ADS)

Kudo, K.; Maeda, H.; Kawakubo, T.; Ootani, Y.; Funaki, M.; Fukui, H.

2006-06-01

The normalized elimination of the small component (NESC) theory, recently proposed by Filatov and Cremer [J. Chem. Phys. 122, 064104 (2005)], is extended to include magnetic interactions and applied to the calculation of the nuclear magnetic shielding in HX (X =F,Cl,Br,I) systems. The NESC calculations are performed at the levels of the zeroth-order regular approximation (ZORA) and the second-order regular approximation (SORA). The calculations show that the NESC-ZORA results are very close to the NESC-SORA results, except for the shielding of the I nucleus. Both the NESC-ZORA and NESC-SORA calculations yield very similar results to the previously reported values obtained using the relativistic infinite-order two-component coupled Hartree-Fock method. The difference between NESC-ZORA and NESC-SORA results is significant for the shieldings of iodine.

Nuclear spin circular dichroism.

PubMed

Vaara, Juha; Rizzo, Antonio; Kauczor, Joanna; Norman, Patrick; Coriani, Sonia

2014-04-07

Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

Biomolecular imaging of 13C-butyrate with dissolution-DNP: Polarization enhancement and formulation for in vivo studies

NASA Astrophysics Data System (ADS)

Flori, Alessandra; Giovannetti, Giulio; Santarelli, Maria Filomena; Aquaro, Giovanni Donato; De Marchi, Daniele; Burchielli, Silvia; Frijia, Francesca; Positano, Vincenzo; Landini, Luigi; Menichetti, Luca

2018-06-01

Magnetic Resonance Spectroscopy of hyperpolarized isotopically enriched molecules facilitates the non-invasive real-time investigation of in vivo tissue metabolism in the time-frame of a few minutes; this opens up a new avenue in the development of biomolecular probes. Dissolution Dynamic Nuclear Polarization is a hyperpolarization technique yielding a more than four orders of magnitude increase in the 13C polarization for in vivo Magnetic Resonance Spectroscopy studies. As reported in several studies, the dissolution Dynamic Nuclear Polarization polarization performance relies on the chemico-physical properties of the sample. In this study, we describe and quantify the effects of the different sample components on the dissolution Dynamic Nuclear Polarization performance of [1-13C]butyrate. In particular, we focus on the polarization enhancement provided by the incremental addition of the glassy agent dimethyl sulfoxide and gadolinium chelate to the formulation. Finally, preliminary results obtained after injection in healthy rats are also reported, showing the feasibility of an in vivo Magnetic Resonance Spectroscopy study with hyperpolarized [1-13C]butyrate using a 3T clinical set-up.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gómez, A. M., E-mail: amgomezl-1@uqvirtual.edu.co; Torres, D. A., E-mail: datorresg@unal.edu.co

The experimental study of nuclear magnetic moments, using the Transient Field technique, makes use of spin-orbit hyperfine interactions to generate strong magnetic fields, above the kilo-Tesla regime, capable to create a precession of the nuclear spin. A theoretical description of such magnetic fields is still under theoretical research, and the use of parametrizations is still a common way to address the lack of theoretical information. In this contribution, a review of the main parametrizations utilized in the measurements of Nuclear Magnetic Moments will be presented, the challenges to create a theoretical description from first principles will be discussed.

Metrics for comparing plasma mass filters

NASA Astrophysics Data System (ADS)

Fetterman, Abraham J.; Fisch, Nathaniel J.

2011-10-01

High-throughput mass separation of nuclear waste may be useful for optimal storage, disposal, or environmental remediation. The most dangerous part of nuclear waste is the fission product, which produces most of the heat and medium-term radiation. Plasmas are well-suited to separating nuclear waste because they can separate many different species in a single step. A number of plasma devices have been designed for such mass separation, but there has been no standardized comparison between these devices. We define a standard metric, the separative power per unit volume, and derive it for three different plasma mass filters: the plasma centrifuge, Ohkawa filter, and the magnetic centrifugal mass filter.

Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

PubMed

Thurber, Kent R; Tycko, Robert

2012-08-28

We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

Single ferromagnetic fluctuations in UCoGe revealed by 73Ge- and 59Co-NMR studies

NASA Astrophysics Data System (ADS)

Manago, Masahiro; Ishida, Kenji; Aoki, Dai

2018-02-01

73Ge and 59Co nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements have been performed on a 73Ge-enriched single-crystalline sample of the ferromagnetic superconductor UCoGe in the paramagnetic state. The 73Ge NQR parameters deduced from NQR and NMR are close to those of another isostructural ferromagnetic superconductor URhGe. The Knight shifts of the Ge and Co sites are well scaled to each other when the magnetic field is parallel to the b or c axis. The hyperfine coupling constants of Ge are estimated to be close to those of Co. The large difference of spin susceptibilities between the a and b axes could lead to the different response of the superconductivity and ferromagnetism with the field parallel to these directions. The temperature dependence of the nuclear spin-lattice relaxation rates 1 /T1 at the two sites is similar to each other above 5 K. These results indicate that the itinerant U-5 f electrons are responsible for the ferromagnetism in this compound, consistent with previous studies. The similarities and differences in the three ferromagnetic superconductors are discussed.

High elongation elastomers

NASA Technical Reports Server (NTRS)

Brady, V. L.; Reed, R.; Merwin, L.; Nissan, R.

1994-01-01

A new class of liquid curable elastomers with unusual strength and elasticity has been developed at the Naval Air Warfare Center Weapons Division, China Lake. Over the years, studies have been conducted on polymer structure and its influence on the mechanical properties of the ensuing composites. Different tools, including nuclear magnetic resonance, have been used. This paper presents a summary of the factors controlling the mechanical behavior of composites produced with the new liquid curable elastomers, including the effects of plasticizers. It also provides an overview of the nuclear magnetic resonance study on polymer structure, the composition and properties of some live and inert formulations produced at China Lake, and some possible peace-time applications for these new elastomeric materials.

Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer

NASA Technical Reports Server (NTRS)

Romalis, Michael; Komack, Tom; Ghost, Rajat

2008-01-01

An experimental nuclear-spin gyroscope is based on an alkali-metal/noblegas co-magnetometer, which automatically cancels the effects of magnetic fields. Whereas the performances of prior nuclear-spin gyroscopes are limited by sensitivity to magnetic fields, this gyroscope is insensitive to magnetic fields and to other external perturbations. In addition, relative to prior nuclear-spin gyroscopes, this one exhibits greater sensitivity to rotation. There is commercial interest in development of small, highly sensitive gyroscopes. The present experimental device could be a prototype for development of nuclear spin gyroscopes suitable for navigation. In comparison with fiber-optic gyroscopes, these gyroscopes would draw less power and would be smaller, lighter, more sensitive, and less costly.

Some concepts of the advanced mass spectrometry at the COMBAS magnetic separator of nuclear reaction products

NASA Astrophysics Data System (ADS)

Artukh, A. G.; Tarantin, N. I.

Proposed is an in-flight measurement method of recoil nuclei masses with the help of a Penning trap located behind the COMBAS magnetic separator for nuclear reaction products. The method is based on the following operations: (i) Accepting the recoil nuclear reaction products by the magnetic separator and decreasing their kinetic energy by degraders. (ii) In-flight transportation of the retarded nuclei into the magnetic field of the Penning trap's solenoid and transforming their remaining longitudinal momentum into orbital rotation by the fringing magnetic field of the solenoid. (iii) Cooling the orbital rotation of the ions by the high-frequency azimuthal electric field of the Penning trap's electric hyperboloid.

A Comparison of FTNMR and FTIR Techniques.

ERIC Educational Resources Information Center

Ahn, Myong-Ku

1989-01-01

Nuclear magnetic resonance and infrared are two spectroscopic methods that commonly use the Fourier transform technique. Discussed are the similarities and differences in the use of the Fourier transform in these two spectroscopic techniques. (CW)

Hybrid systems for transuranic waste transmutation in nuclear power reactors: state of the art and future prospects

NASA Astrophysics Data System (ADS)

Yurov, D. V.; Prikhod'ko, V. V.

2014-11-01

The features of subcritical hybrid systems (HSs) are discussed in the context of burning up transuranic wastes from the U-Pu nuclear fuel cycle. The advantages of HSs over conventional atomic reactors are considered, and fuel cycle closure alternatives using HSs and fast neutron reactors are comparatively evaluated. The advantages and disadvantages of two HS types with neutron sources (NSs) of widely different natures -- nuclear spallation in a heavy target by protons and nuclear fusion in magnetically confined plasma -- are discussed in detail. The strengths and weaknesses of HSs are examined, and demand for them for closing the U-Pu nuclear fuel cycle is assessed.

An improved nuclear magnetic resonance spectrometer

NASA Technical Reports Server (NTRS)

Elleman, D. D.; Manatt, S. L.

1967-01-01

Cylindrical sample container provides a high degree of nuclear stabilization to a nuclear magnetic resonance /nmr/ spectrometer. It is placed coaxially about the nmr insert and contains reference sample that gives a signal suitable for locking the field and frequency of an nmr spectrometer with a simple audio modulation system.

Edward Purcell and Nuclear Magnetic Resonance (NMR)

Science.gov Websites

"development of new methods for nuclear magnetic precision measurements and discoveries in educated and inspired a generation of physicists, who refer to it often, and depend on it utterly.1 Purcell : A Precise Determination of the Proton Magnetic Moment in Bohr Magnetons; Physical Review, Vol. 76

Coherent manipulation of non-thermal spin order in optical nuclear polarization experiments

NASA Astrophysics Data System (ADS)

Buntkowsky, Gerd; Ivanov, Konstantin L.; Zimmermann, Herbert; Vieth, Hans-Martin

2017-03-01

Time resolved measurements of Optical Nuclear Polarization (ONP) have been performed on hyperpolarized triplet states in molecular crystals created by light excitation. Transfer of the initial electron polarization to nuclear spins has been studied in the presence of radiofrequency excitation; the experiments have been performed with different pulse sequences using different doped molecular systems. The experimental results clearly demonstrate the dominant role of coherent mechanisms of spin order transfer, which manifest themselves in well pronounced oscillations. These oscillations are of two types, precessions and nutations, having characteristic frequencies, which are the same for the different molecular systems and the pulse sequences applied. Hence, precessions and nutations constitute a general feature of polarization transfer in ONP experiments. In general, coherent manipulation of spin order transfer creates a powerful resource for improving the performance of the ONP method, which paves the way to strong signal enhancement in nuclear magnetic resonance.

Nuclear shieldings with the SSB-D functional.

PubMed

Armangué, Lluís; Solà, Miquel; Swart, Marcel

2011-02-24

The recently reported SSB-D functional [J. Chem. Phys. 2009, 131, 094103] is used to check the performance for obtaining nuclear magnetic resonance (NMR) shielding constants. Four different databases were studied, which contain a diversity of molecules and nuclear shielding constants. The SSB-D functional is compared with its "parent" functionals (PBE, OPBE), the KT2 functional that was designed specially for NMR applications and the coupled cluster CCSD(T) method. The best performance for the experimentally most-used elements ((1)H, (13)C) is obtained for the SSB-D and KT2 functionals.

Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic

NASA Astrophysics Data System (ADS)

Lovchinsky, I.; Sushkov, A. O.; Urbach, E.; de Leon, N. P.; Choi, S.; De Greve, K.; Evans, R.; Gertner, R.; Bersin, E.; Müller, C.; McGuinness, L.; Jelezko, F.; Walsworth, R. L.; Park, H.; Lukin, M. D.

2016-02-01

Nuclear magnetic resonance spectroscopy is a powerful tool for the structural analysis of organic compounds and biomolecules but typically requires macroscopic sample quantities. We use a sensor, which consists of two quantum bits corresponding to an electronic spin and an ancillary nuclear spin, to demonstrate room temperature magnetic resonance detection and spectroscopy of multiple nuclear species within individual ubiquitin proteins attached to the diamond surface. Using quantum logic to improve readout fidelity and a surface-treatment technique to extend the spin coherence time of shallow nitrogen-vacancy centers, we demonstrate magnetic field sensitivity sufficient to detect individual proton spins within 1 second of integration. This gain in sensitivity enables high-confidence detection of individual proteins and allows us to observe spectral features that reveal information about their chemical composition.

Effect of different catalysts on urea-formaldehyde resin synthesis

Treesearch

Qi-Ning Sun; Chung-Yun Hse; Todd F. Shupe

2014-01-01

Four catalysts (H2SO4, HCl, H3PO4, and NaOH/NH4OH) were studied in the preparation of melamine modified urea– formaldehyde (UFM) resins. 13C-nuclear magnetic resonance spectroscopic analysis of the UFM resins at different synthesis stages revealed the...

Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

PubMed

Vogel, Michael W; Giorni, Andrea; Vegh, Viktor; Pellicer-Guridi, Ruben; Reutens, David C

2016-01-01

We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

Capacitor-based detection of nuclear magnetization: nuclear quadrupole resonance of surfaces.

PubMed

Gregorovič, Alan; Apih, Tomaž; Kvasić, Ivan; Lužnik, Janko; Pirnat, Janez; Trontelj, Zvonko; Strle, Drago; Muševič, Igor

2011-03-01

We demonstrate excitation and detection of nuclear magnetization in a nuclear quadrupole resonance (NQR) experiment with a parallel plate capacitor, where the sample is located between the two capacitor plates and not in a coil as usually. While the sensitivity of this capacitor-based detection is found lower compared to an optimal coil-based detection of the same amount of sample, it becomes comparable in the case of very thin samples and even advantageous in the proximity of conducting bodies. This capacitor-based setup may find its application in acquisition of NQR signals from the surface layers on conducting bodies or in a portable tightly integrated nuclear magnetic resonance sensor. Copyright © 2010 Elsevier Inc. All rights reserved.

A polyvalent harmonic coil testing method for small-aperture magnets

NASA Astrophysics Data System (ADS)

Arpaia, Pasquale; Buzio, Marco; Golluccio, Giancarlo; Walckiers, Louis

2012-08-01

A method to characterize permanent and fast-pulsed iron-dominated magnets with small apertures is presented. The harmonic coil measurement technique is enhanced specifically for small-aperture magnets by (1) in situ calibration, for facing search-coil production inaccuracy, (2) rotating the magnet around its axis, for correcting systematic effects, and (3) measuring magnetic fluxes by stationary coils at different angular positions for measuring fast pulsed magnets. This method allows a quadrupole magnet for particle accelerators to be characterized completely, by assessing multipole field components, magnetic axis position, and field direction. In this paper, initially the metrological problems arising from testing small-aperture magnets are highlighted. Then, the basic ideas of the proposed method and the architecture of the corresponding measurement system are illustrated. Finally, experimental validation results are shown for small-aperture permanent and fast-ramped quadrupole magnets for the new linear accelerator Linac4 at CERN (European Organization for Nuclear Research).

Progress in Spin Dynamics Solid-State Nuclear Magnetic Resonance with the Application of Floquet-Magnus Expansion to Chemical Shift Anisotropy

PubMed Central

Mananga, Eugene Stephane

2013-01-01

The purpose of this article is to present an historical overview of theoretical approaches used for describing spin dynamics under static or rotating experiments in solid state nuclear magnetic resonance. The article gives a brief historical overview for major theories in nuclear magnetic resonance and the promising theories. We present the first application of Floquet-Magnus expansion to chemical shift anisotropy when irradiated by BABA pulse sequence. PMID:23711337

MEMS-Based Force-Detected Nuclear Magnetic Resonance (FDNMR) Spectrometer

NASA Technical Reports Server (NTRS)

Lee, Choonsup; Butler, Mark C.; Elgammal, Ramez A.; George, Thomas; Hunt, Brian; Weitekamp, Daniel P.

2006-01-01

Nuclear Magnetic Resonance (NMR) spectroscopy allows assignment of molecular structure by acquiring the energy spectrum of nuclear spins in a molecule, and by interpreting the symmetry and positions of resonance lines in the spectrum. As such, NMR has become one of the most versatile and ubiquitous spectroscopic methods. Despite these tremendous successes, NMR experiments suffer from inherent low sensitivity due to the relatively low energy of photons in the radio frequency (rt) region of the electromagnetic spectrum. Here, we describe a high-resolution spectroscopy in samples with diameters in the micron range and below. We have reported design and fabrication of force-detected nuclear magnetic resonance (FDNMR).

Mathematical Development and Computational Analysis of Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) Based on Bloch Nuclear Magnetic Resonance (NMR) Diffusion Model for Myocardial Motion.

PubMed

Dada, Michael O; Jayeoba, Babatunde; Awojoyogbe, Bamidele O; Uno, Uno E; Awe, Oluseyi E

2017-09-13

Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) is a tagged image analysis method that can measure myocardial motion and strain in near real-time and is considered a potential candidate to make magnetic resonance tagging clinically viable. However, analytical expressions of radially tagged transverse magnetization in polar coordinates (which is required to appropriately describe the shape of the heart) have not been explored because the physics required to directly connect myocardial deformation of tagged Nuclear Magnetic Resonance (NMR) transverse magnetization in polar geometry and the appropriate harmonic phase parameters are not yet available. The analytical solution of Bloch NMR diffusion equation in spherical geometry with appropriate spherical wave tagging function is important for proper analysis and monitoring of heart systolic and diastolic deformation with relevant boundary conditions. In this study, we applied Harmonic Phase MRI method to compute the difference between tagged and untagged NMR transverse magnetization based on the Bloch NMR diffusion equation and obtained radial wave tagging function for analysis of myocardial motion. The analytical solution of the Bloch NMR equations and the computational simulation of myocardial motion as developed in this study are intended to significantly improve healthcare for accurate diagnosis, prognosis and treatment of cardiovascular related deceases at the lowest cost because MRI scan is still one of the most expensive anywhere. The analysis is fundamental and significant because all Magnetic Resonance Imaging techniques are based on the Bloch NMR flow equations.

Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic.

PubMed

Lovchinsky, I; Sushkov, A O; Urbach, E; de Leon, N P; Choi, S; De Greve, K; Evans, R; Gertner, R; Bersin, E; Müller, C; McGuinness, L; Jelezko, F; Walsworth, R L; Park, H; Lukin, M D

2016-02-19

Nuclear magnetic resonance spectroscopy is a powerful tool for the structural analysis of organic compounds and biomolecules but typically requires macroscopic sample quantities. We use a sensor, which consists of two quantum bits corresponding to an electronic spin and an ancillary nuclear spin, to demonstrate room temperature magnetic resonance detection and spectroscopy of multiple nuclear species within individual ubiquitin proteins attached to the diamond surface. Using quantum logic to improve readout fidelity and a surface-treatment technique to extend the spin coherence time of shallow nitrogen-vacancy centers, we demonstrate magnetic field sensitivity sufficient to detect individual proton spins within 1 second of integration. This gain in sensitivity enables high-confidence detection of individual proteins and allows us to observe spectral features that reveal information about their chemical composition. Copyright © 2016, American Association for the Advancement of Science.

Francis Bitter National Laboratory quarterly progress report, July 1, 1972--September 30, 1972

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1972-10-31

Reports on research projects at Francis Bitter National Magnet Laboratory are presented on 19 different topics including the following: far infrared magneto-optics; quantum optics; soft x-rays and laser-produced plasmas; magneto-optical theory; magnetism and superconductivity; Mossbauer effect studies; superconducting thin films; amorphous semiconductors and superconductivity; nuclear magnetic resonance of biomolecules; low magnetic fields; superconducting medical magnet; magnetically guided catheters; magnetic separation; high current switching; development of guided electromagnetic flight; Alcator; high voltage discharges in cryocables; and low temperature thermometry in high magnetic fields. The Magnet Research and Technology Program and reports of visiting scientists are also included in this report. Reportsmore » on some research not supported by NSF are included, and the supporting agencies are indicated. A list of publications and speeches presented at meetings during the quarter covered by this report are included in an appendix.« less

Investigation of the Possibility of Using Nuclear Magnetic Spin Alignment

NASA Technical Reports Server (NTRS)

Dent, William V., Jr.

1998-01-01

The goal of the program to investigate a "Gasdynamic fusion propulsion system for space exploration" is to develop a fusion propulsion system for a manned mission to the planet mars. A study using Deuterium and Tritium atoms are currently in progress. When these atoms under-go fusion, the resulting neutrons and alpha particles are emitted in random directions (isotropically). The probable direction of emission is equal for all directions, thus resulting in wasted energy, massive shielding and cooling requirements, and serious problems with the physics of achieving fusion. If the nuclear magnetic spin moments of the deuterium and tritium nuclei could be precisely aligned at the moment of fusion, the stream of emitted neutrons could be directed out the rear of the spacecraft for thrust and the alpha particles directed forward into an electromagnet ot produce electricity to continue operating the fusion engine. The following supporting topics are discussed: nuclear magnetic moments and spin precession in magnetic field, nuclear spin quantum mechanics, kinematics of nuclear reactions, and angular distribution of particles.

Solute-solvent contact by intermolecular cross relaxation. I. The nature of the water-hydrophobic interface.

PubMed

Nordstierna, Lars; Yushmanov, Pavel V; Furó, István

2006-08-21

Intermolecular cross-relaxation rates between solute and solvent were measured by {1H} 19F nuclear magnetic resonance experiments in aqueous molecular solutions of ammonium perfluoro-octanoate and sodium trifluoroacetate. The experiments performed at three different magnetic fields provide frequency-dependent cross-relaxation rates which demonstrate clearly the lack of extreme narrowing for nuclear spin relaxation by diffusionally modulated intermolecular interactions. Supplemented by suitable intramolecular cross-relaxation, longitudinal relaxation, and self-diffusion data, the obtained cross-relaxation rates are evaluated within the framework of recent relaxation models and provide information about the hydrophobic hydration. In particular, water dynamics around the trifluoromethyl group in ammonium perfluoro-octanoate are more retarded than that in the smaller trifluoroacetate.

Perturbation approach for nuclear magnetic resonance solid-state quantum computation

DOE PAGES

Berman, G. P.; Kamenev, D. I.; Tsifrinovich, V. I.

2003-01-01

A dynmore » amics of a nuclear-spin quantum computer with a large number ( L = 1000 ) of qubits is considered using a perturbation approach. Small parameters are introduced and used to compute the error in an implementation of an entanglement between remote qubits, using a sequence of radio-frequency pulses. The error is computed up to the different orders of the perturbation theory and tested using exact numerical solution.« less

Neutron diffraction study of Tb0.5Ho0.5Mn2Si2

NASA Astrophysics Data System (ADS)

Pandey, Swati; Siruguri, Vasudeva; Rawat, Rajeev

2018-02-01

The magnetic properties of tetragonal polycrystalline intermetallic compound Tb0.5Ho0.5Mn2Si2 have been investigated using temperature dependent dc magnetic susceptibility and neutron powder diffraction studies. Results of high temperature susceptibility data shows anomaly at TN = 510 K while low temperature susceptibility data indicate two successive anomalies at T1 = 11 K and T2 = 25 K. Metamagnetic transition is observed in magnetization versus field curves. Our neutron diffraction results indicate three different magnetic regions with different magnetic structures. Neutron diffraction data shows that below T2, the intensities of some of the nuclear peaks get enhanced indicating ferromagnetic ordering, while additional magnetic reflections are observed below T1, indicating antiferromagnetic order. Ordering of rare earth sublattice at low temperature rearranges the ordering of Mn sublattice and results in reorientation of Mn spins at T1. At 2 K Tb/Ho moments are aligned along c-axis while Mn moments are aligned perpendicular to c-axis.

Superconducting Magnets for the 12 GeV Upgrade at Jefferson Lab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fair, Ruben J.; Young, Glenn R.

2015-06-01

Jefferson Laboratory is embarked on an energy upgrade to its flagship continuous electron beam accelerator in order to expand the scope of its research capabilities and probe further into the structure of nuclear particles. The 12 GeV upgrade includes the design, manufacture, integration, installation and commissioning of eight different superconducting magnets in three separate experimental halls. The effort involves other national laboratories, universities and industry spanning three countries. This paper will summarize the key characteristics of these magnets, ranging in size from 0.2 to 23 MJ in stored energy, and featuring many different types and configurations. The paper will alsomore » give an overview of the specific technical challenges for each magnet, and a status report on magnet manufacture and expected delivery dates. The 12GeV upgrade at J-Lab represents the largest superconducting magnet fabrication and installation program currently ongoing in the United States and this paper will present the breadth of collaborations supporting it.« less

Basic physics of nuclear magnetic resonance.

PubMed

Patz, S

1986-01-01

This review of basic physics of nuclear magnetic resonance (NMR) discusses precession of magnetic nuclei in a static external field, introduces the concept of the rotating frame, and describes excitation of nuclei by an RF field. Treats subject of T1 and T2 relaxation from the dual viewpoints of (1) phenomena of relaxation times for both the longitudinal and transverse magnetization and (2) relaxation resulting from local field fluctuations. It describes practical ways in which T1 and T2 are measured (i.e., inversion recovery and spin-echo) and gives the value of the nuclear magnetization in thermodynamic equilibrium with a static external field. It discusses the reduction of NMR signal resulting from saturation. These concepts are related to clinical use with a set of four spin-echo images of a human head.

The nuclear magnetic moment of 208Bi and its relevance for a test of bound-state strong-field QED

NASA Astrophysics Data System (ADS)

Schmidt, S.; Billowes, J.; Bissell, M. L.; Blaum, K.; Garcia Ruiz, R. F.; Heylen, H.; Malbrunot-Ettenauer, S.; Neyens, G.; Nörtershäuser, W.; Plunien, G.; Sailer, S.; Shabaev, V. M.; Skripnikov, L. V.; Tupitsyn, I. I.; Volotka, A. V.; Yang, X. F.

2018-04-01

The hyperfine structure splitting in the 6p3 3/2 4S → 6p2 7 s 1/2 4P transition at 307 nm in atomic 208Bi was measured with collinear laser spectroscopy at ISOLDE, CERN. The hyperfine A and B factors of both states were determined with an order of magnitude improved accuracy. Based on these measurements, theoretical input for the hyperfine structure anomaly, and results from hyperfine measurements on hydrogen-like and lithium-like 209Bi80+,82+, the nuclear magnetic moment of 208Bi has been determined to μ (208Bi) = + 4.570 (10)μN. Using this value, the transition energy of the ground-state hyperfine splitting in hydrogen-like and lithium-like 208Bi80+,82+ and their specific difference of -67.491(5)(148) meV are predicted. This provides a means for an experimental confirmation of the cancellation of nuclear structure effects in the specific difference in order to exclude such contributions as the cause of the hyperfine puzzle, the recently reported 7-σ discrepancy between experiment and bound-state strong-field QED calculations of the specific difference in the hyperfine structure splitting of 209Bi80+,82+.

Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study

PubMed Central

Vegh, Viktor; Reutens, David C.

2016-01-01

Object We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. Materials and Methods The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. Results A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20–50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. Conclusions A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably. PMID:27271886

Inhomogeneous nuclear spin polarization induced by helicity-modulated optical excitation of fluorine-bound electron spins in ZnSe

NASA Astrophysics Data System (ADS)

Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.

2015-12-01

Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.

Application of electronic paramagnetic, nuclear magnetic, γ-nuclear magnetic resonance, and defibrillation in experimental biology and medecine

NASA Astrophysics Data System (ADS)

Piruzyan, L. A.

2005-08-01

Nowadays an attention is paid to pathbreaking approaches to the therapy of different pathologies with EPR, NMR and NGR dialysis and mechanisms of physical factors influence in prophylactics and therapy of a number of diseases. Any pathology is evidently begins its development in atomic-molecular levels earlier then any morphologic alterations in tissues can be detected. We have studied the alterations of FR content in liver, spleen and brain in hypoxia and hyperoxia conditions. Under hypoxia and hyperoxia the FR concentrations are equal in all organs and tissues. However this ratio is different for some forms of leucosis. For different leucosis types gas mixtures the most adequate for the current pathology should be developed. Then we represent the method of biologic objects treatment with the energy of super-high frequency field (SIT) and the instrument for its performance. The study of magnetic heterogeneity of biologic systems proposes the new approach and a set of methods for medical and scientific purpose. Application of combined with chemotherapy extraction of anionic and cationic radicals from bloodstream using EPRD, NMRD and NGRD influence and also the single ions separate extraction using NGRD are able to detect and perhaps to cure their appearance in a period before neoformation. These studies should be carried out experimentally and clinically.

Spins and parities of the odd-A P isotopes within a relativistic mean-field model and elastic magnetic electron-scattering theory

NASA Astrophysics Data System (ADS)

Wang, Zaijun; Ren, Zhongzhou; Dong, Tiekuang; Xu, Chang

2014-08-01

The ground-state spins and parities of the odd-A phosphorus isotopes 25-47P are studied with the relativistic mean-field (RMF) model and relativistic elastic magnetic electron-scattering theory (REMES). Results of the RMF model with the NL-SH, TM2, and NL3 parameters show that the 2s1/2 and 1d3/2 proton level inversion may occur for the neutron-rich isotopes 37-47P, and, consequently, the possible spin-parity values of 37-47P may be 3/2+, which, except for P47, differs from those given by the NUBASE2012 nuclear data table by Audi et al. Calculations of the elastic magnetic electron scattering of 37-47P with the single valence proton in the 2s1/2 and 1d3/2 state show that the form factors have significant differences. The results imply that elastic magnetic electron scattering can be a possible way to study the 2s1/2 and 1d3/2 level inversion and the spin-parity values of 37-47P. The results can also provide new tests as to what extent the RMF model, along with its various parameter sets, is valid for describing the nuclear structures. In addition, the contributions of the upper and lower components of the Dirac four-spinors to the form factors and the isotopic shifts of the magnetic form factors are discussed.

Feedback control for manipulating magnetization in spin-exchange optical pumping system

NASA Astrophysics Data System (ADS)

Zhang, Ke; Li, Jun; Jiang, Min; Zhao, Nan; Peng, XinHua

2018-08-01

Control of magnetization plays an important role in the scientific and technological field of manipulating spin systems. In this work, we study the problem of manipulating nuclear magnetization in the spin-exchange optical pumping system, including accelerating the recovery of nuclear polarization and fixing it on a specific desired state. A real-time feedback control strategy is exploited here. We have also done some numerical simulations, with the results clearly demonstrating the effectiveness of our method, that the nuclear magnetization is able to be driven towards the equilibrium state at a much faster speed and also can be stabilized to a target state. We expect that our feedback control method can find applications in gyro experiments.

Core-dependent and ligand-dependent relativistic corrections to the nuclear magnetic shieldings in MH4-n Y n (n = 0-4; M = Si, Ge, Sn, and Y = H, F, Cl, Br, I) model compounds.

PubMed

Maldonado, Alejandro F; Aucar, Gustavo A; Melo, Juan I

2014-09-01

The nuclear magnetic shieldings of Si, Ge, and Sn in MH(4-n) Y(n) (M = Si, Ge, Sn; Y = F, Cl, Br, I and n = 1-4) molecular systems are highly influenced by the substitution of one or more hydrogens by heavy-halogen atoms. We applied the linear response elimination of small components (LRESC) formalism to calculate those shieldings and learn whether including only a few of the leading relativistic correction terms is sufficient to be able to quantitatively reproduce the full relativistic value. It was observed that the nuclear magnetic shieldings change as the number of heavy halogen substituents and their weights vary, and the pattern of σ(M) generally does not exhibit the normal halogen dependence (NHD) behavior that can be seen in similar molecular systems containing carbon atoms. We also analyzed each relativistic correction afforded by the LRESC method and split them in two: core-dependent and ligand-dependent contributions; we then looked for the electronic mechanisms involved in the different relativistic effects and in the total relativistic value. Based on this analysis, we were able to study the electronic mechanism involved in a recently proposed relativistic effect, the "heavy atom effect on vicinal heavy atom" (HAVHA), in more detail. We found that the main electronic mechanism is the spin-orbit or σ p (T(3)) correction, although other corrections such as σ p (S(1)) and σ p (S(3)) are also important. Finally, we analyzed proton magnetic shieldings and found that, for molecules containing Sn as the central atom, σ(H) decreases as the number of heavy halogen substituents (of the same type: either F, Cl, or Br) increases, albeit at different rates for different halogens. σ(H) only increase as the number of halogen substituents increases if the halogen is iodine.

Nuclear Magnetic Resonance Trackbed Moisture Sensor System

DOT National Transportation Integrated Search

2018-02-01

In this initial phase, conducted from March 2015 through December 2016, Vista Clara and its subcontractor Zetica Rail successfully developed and tested a man-portable, non-invasive spot-check nuclear magnetic resonance (NMR) moisture sensor that dire...

Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

PubMed

Singh, Gurpreet; Mohanty, B P; Saini, G S S

2016-02-15

Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide. Copyright © 2015 Elsevier B.V. All rights reserved.

Dark state polarizing a nuclear spin in the vicinity of a nitrogen-vacancy center

NASA Astrophysics Data System (ADS)

Wang, Yang-Yang; Qiu, Jing; Chu, Ying-Qi; Zhang, Mei; Cai, Jianming; Ai, Qing; Deng, Fu-Guo

2018-04-01

The nuclear spin in the vicinity of a nitrogen-vacancy (NV) center possesses long coherence time and convenient manipulation assisted by the strong hyperfine interaction with the NV center. It is suggested for the subsequent quantum information storage and processing after appropriate initialization. However, current experimental schemes are either sensitive to the inclination and magnitude of the magnetic field or require thousands of repetitions to achieve successful realization. Here, we propose a method to polarize a 13C nuclear spin in the vicinity of an NV center via a dark state. We demonstrate theoretically and numerically that it is robust to polarize various nuclear spins with different hyperfine couplings and noise strengths.

Reversible interactions with para-hydrogen enhance NMR sensitivity by polarization transfer.

PubMed

Adams, Ralph W; Aguilar, Juan A; Atkinson, Kevin D; Cowley, Michael J; Elliott, Paul I P; Duckett, Simon B; Green, Gary G R; Khazal, Iman G; López-Serrano, Joaquín; Williamson, David C

2009-03-27

The sensitivity of both nuclear magnetic resonance spectroscopy and magnetic resonance imaging is very low because the detected signal strength depends on the small population difference between spin states even in high magnetic fields. Hyperpolarization methods can be used to increase this difference and thereby enhance signal strength. This has been achieved previously by incorporating the molecular spin singlet para-hydrogen into hydrogenation reaction products. We show here that a metal complex can facilitate the reversible interaction of para-hydrogen with a suitable organic substrate such that up to an 800-fold increase in proton, carbon, and nitrogen signal strengths are seen for the substrate without its hydrogenation. These polarized signals can be selectively detected when combined with methods that suppress background signals.

Magnet Design Considerations for Fusion Nuclear Science Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Y.; Kessel, C.; El-Guebaly, L.

2016-06-01

The Fusion Nuclear Science Facility (FNSF) is a nuclear confinement facility that provides a fusion environment with components of the reactor integrated together to bridge the technical gaps of burning plasma and nuclear science between the International Thermonuclear Experimental Reactor (ITER) and the demonstration power plant (DEMO). Compared with ITER, the FNSF is smaller in size but generates much higher magnetic field, i.e., 30 times higher neutron fluence with three orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5more » T at the plasma center with a plasma major radius of 4.8 m and a minor radius of 1.2 m and a peak field of 15.5 T on the toroidal field (TF) coils for the FNSF. Both low-temperature superconductors (LTS) and high-temperature superconductors (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology. The higher magnetic field can be achieved by using the high-performance ternary restacked-rod process Nb3Sn strands for TF magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high-aspect-ratio rectangular CICC design are evaluated for FNSF magnets, but low-activation-jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. The material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.« less

Magnet design considerations for Fusion Nuclear Science Facility

DOE PAGES

Zhai, Yuhu; Kessel, Chuck; El-guebaly, Laila; ...

2016-02-25

The Fusion Nuclear Science Facility (FNSF) is a nuclear confinement facility to provide a fusion environment with components of the reactor integrated together to bridge the technical gaps of burning plasma and nuclear science between ITER and the demonstration power plant (DEMO). Compared to ITER, the FNSF is smaller in size but generates much higher magnetic field, 30 times higher neutron fluence with 3 orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5 T at the plasma center withmore » plasma major radius of 4.8 m and minor radius of 1.2 m, and a peak field of 15.5 T on the TF coils for FNSF. Both low temperature superconductor (LTS) and high temperature superconductor (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology. The higher magnetic field can be achieved by using the high performance ternary Restack Rod Process (RRP) Nb3Sn strands for toroidal field (TF) magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high aspect ratio rectangular CICC design are evaluated for FNSF magnets but low activation jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. As a result, the material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.« less

Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Blanchard, J. W.; Sjolander, T. F.; King, J. P.; Ledbetter, M. P.; Levine, E. H.; Bajaj, V. S.; Budker, D.; Pines, A.

2015-12-01

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from the effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultralow-field NMR measurements of residual dipolar couplings in acetonitrile-2-13C aligned in stretched polyvinyl acetate gels. This permits the investigation of dipolar couplings as a perturbation on the indirect spin-spin J coupling in the absence of an applied magnetic field. As a consequence of working at zero magnetic field, we observe terms of the dipole-dipole coupling Hamiltonian that are invisible in conventional high-field NMR. This technique expands the capabilities of zero- to ultralow-field NMR and has potential applications in precision measurement of subtle physical interactions, chemical analysis, and characterization of local mesoscale structure in materials.

On the universality of I-Love-Q relations in magnetized neutron stars

NASA Astrophysics Data System (ADS)

Haskell, B.; Ciolfi, R.; Pannarale, F.; Rezzolla, L.

2014-02-01

Recently, general relations among the quadrupole moment (Q), the moment of inertia (I) and the tidal deformability (Love number) of a neutron star were shown to exist. They are nearly independent of the nuclear matter equation of state and would be of great aid in extracting parameters from observed gravitational waves and in testing general relativity. These relations, however, do not account for strong magnetic fields. We consider this problem by studying the effect of a strong magnetic field on slowly rotating relativistic neutron stars and show that, for simple magnetic field configurations that are purely poloidal or purely toroidal, the relation between Q and I is again nearly universal. However, different magnetic field geometries lead to different I-Q relations, and, in the case of a more realistic twisted-torus magnetic field configuration, the relation depends significantly on the equation of state, losing its universality. I-Love-Q relations must thus be used with very great care, since universality is lost for stars with long spin periods, i.e. P ≳ 10 s, and strong magnetic fields, i.e. B ≳ 1012 G.

Computational Modeling of the Spatial Distribution and Temporal Decay of Geomagnetically Trapped Debris of a High Altitude Nuclear Detonation

DTIC Science & Technology

2007-06-01

effects of the magnetic bubble on the dispersion and trapping efficiency of the particles is studied and reported. 15. NUMBER OF PAGES 263 14...efficiency of the particles is studied and reported. vi THIS PAGE INTENTIONALLY LEFT BLANK vii TABLE OF CONTENTS I. INTRODUCTION...single and much lower yield nuclear weapons at many different altitudes. The conclusion of our study and research at USSTRATCOM was that a modeling

Para-hydrogen raser delivers sub-millihertz resolution in nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Suefke, Martin; Lehmkuhl, Sören; Liebisch, Alexander; Blümich, Bernhard; Appelt, Stephan

2017-06-01

The precision of nuclear magnetic resonance spectroscopy (NMR) is limited by the signal-to-noise ratio, the measurement time Tm and the linewidth Δν = 1/(πT2). Overcoming the T 2 limit is possible if the nuclear spins of a molecule emit continuous radio waves. Lasers and masers are self-organized systems which emit coherent radiation in the optical and micro-wave regime. Both are based on creating a population inversion of specific energy states. Here we show continuous oscillations of proton spins of organic molecules in the radiofrequency regime (raser). We achieve this by coupling a population inversion created through signal amplification by reversible exchange (SABRE) to a high-quality-factor resonator. For the case of 15N labelled molecules, we observe multi-mode raser activity, which reports different spin quantum states. The corresponding 1H-15N J-coupled NMR spectra exhibit unprecedented sub-millihertz resolution and can be explained assuming two-spin ordered quantum states. Our findings demonstrate a substantial improvement in the frequency resolution of NMR.

Dynamic nuclear spin polarization in the resonant laser excitation of an InGaAs quantum dot.

PubMed

Högele, A; Kroner, M; Latta, C; Claassen, M; Carusotto, I; Bulutay, C; Imamoglu, A

2012-05-11

Resonant optical excitation of lowest-energy excitonic transitions in self-assembled quantum dots leads to nuclear spin polarization that is qualitatively different from the well-known optical orientation phenomena. By carrying out a comprehensive set of experiments, we demonstrate that nuclear spin polarization manifests itself in quantum dots subjected to finite external magnetic field as locking of the higher energy Zeeman transition to the driving laser field, as well as the avoidance of the resonance condition for the lower energy Zeeman branch. We interpret our findings on the basis of dynamic nuclear spin polarization originating from noncollinear hyperfine interaction and find excellent agreement between experiment and theory. Our results provide evidence for the significance of noncollinear hyperfine processes not only for nuclear spin diffusion and decay, but also for buildup dynamics of nuclear spin polarization in a coupled electron-nuclear spin system.

Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy

NASA Astrophysics Data System (ADS)

Afach, S.; Ayres, N. J.; Ban, G.; Bison, G.; Bodek, K.; Chowdhuri, Z.; Daum, M.; Fertl, M.; Franke, B.; Griffith, W. C.; Grujić, Z. D.; Harris, P. G.; Heil, W.; Hélaine, V.; Kasprzak, M.; Kermaidic, Y.; Kirch, K.; Knowles, P.; Koch, H.-C.; Komposch, S.; Kozela, A.; Krempel, J.; Lauss, B.; Lefort, T.; Lemière, Y.; Mtchedlishvili, A.; Musgrave, M.; Naviliat-Cuncic, O.; Pendlebury, J. M.; Piegsa, F. M.; Pignol, G.; Plonka-Spehr, C.; Prashanth, P. N.; Quéméner, G.; Rawlik, M.; Rebreyend, D.; Ries, D.; Roccia, S.; Rozpedzik, D.; Schmidt-Wellenburg, P.; Severijns, N.; Thorne, J. A.; Weis, A.; Wursten, E.; Wyszynski, G.; Zejma, J.; Zenner, J.; Zsigmond, G.

2015-10-01

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 μ T magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1 pT /cm . This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

Stabilization of the electron-nuclear spin orientation in quantum dots by the nuclear quadrupole interaction.

PubMed

Dzhioev, R I; Korenev, V L

2007-07-20

The nuclear quadrupole interaction eliminates the restrictions imposed by hyperfine interaction on the spin coherence of an electron and nuclei in a quantum dot. The strain-induced nuclear quadrupole interaction suppresses the nuclear spin flip and makes possible the zero-field dynamic nuclear polarization in self-organized InP/InGaP quantum dots. The direction of the effective nuclear magnetic field is fixed in space, thus quenching the magnetic depolarization of the electron spin in the quantum dot. The quadrupole interaction suppresses the zero-field electron spin decoherence also for the case of nonpolarized nuclei. These results provide a new vision of the role of the nuclear quadrupole interaction in nanostructures: it elongates the spin memory of the electron-nuclear system.

Stabilization of the Electron-Nuclear Spin Orientation in Quantum Dots by the Nuclear Quadrupole Interaction

NASA Astrophysics Data System (ADS)

Dzhioev, R. I.; Korenev, V. L.

2007-07-01

The nuclear quadrupole interaction eliminates the restrictions imposed by hyperfine interaction on the spin coherence of an electron and nuclei in a quantum dot. The strain-induced nuclear quadrupole interaction suppresses the nuclear spin flip and makes possible the zero-field dynamic nuclear polarization in self-organized InP/InGaP quantum dots. The direction of the effective nuclear magnetic field is fixed in space, thus quenching the magnetic depolarization of the electron spin in the quantum dot. The quadrupole interaction suppresses the zero-field electron spin decoherence also for the case of nonpolarized nuclei. These results provide a new vision of the role of the nuclear quadrupole interaction in nanostructures: it elongates the spin memory of the electron-nuclear system.

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-02-02

This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-02-02

This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

Chiral discrimination in NMR spectroscopy: computation of the relevant molecular pseudoscalars

NASA Astrophysics Data System (ADS)

Buckingham, A. David; Lazzeretti, Paolo; Pelloni, Stefano

2015-07-01

Nuclear magnetic resonance (NMR) is normally blind to chirality but it has been predicted that precessing nuclear spins in a strong magnetic field induce a rotating electric polarisation that is of opposite sign for enantiomers. The polarisation is determined by two pseudoscalars, ? and ?. The former arises from the distortion of the electronic structure by the nuclear magnetic moment in the presence of the strong magnetic field and is equivalent to the linear effect of an electric field on the nuclear shielding tensor. ? determines the temperature-dependent partial orientation of the permanent electric dipole moment of the molecule by the antisymmetric part of the nuclear shielding tensor. Computations of these two contributions are reported for the nuclei in the chiral molecules N-methyloxaziridine, 2-methyloxirane, 1,3-dimethylallene, 1-fluoroethanol, 2-fluoroazirine, 1,2-M-dioxin, 1,2-M-dithiin, 1,2-M-diselenin and 1,2-M-ditellurin. For strongly dipolar molecules, ? is typically two to three orders of magnitude greater than ?, raising hopes for the detection of chirality in NMR spectroscopy. This paper is dedicated to the memory of Prof. Nicholas Handy, F.R.S.

Robust techniques for polarization and detection of nuclear spin ensembles

NASA Astrophysics Data System (ADS)

Scheuer, Jochen; Schwartz, Ilai; Müller, Samuel; Chen, Qiong; Dhand, Ish; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

2017-11-01

Highly sensitive nuclear spin detection is crucial in many scientific areas including nuclear magnetic resonance spectroscopy, magnetic resonance imaging (MRI), and quantum computing. The tiny thermal nuclear spin polarization represents a major obstacle towards this goal which may be overcome by dynamic nuclear spin polarization (DNP) methods. The latter often rely on the transfer of the thermally polarized electron spins to nearby nuclear spins, which is limited by the Boltzmann distribution of the former. Here we utilize microwave dressed states to transfer the high (>92 % ) nonequilibrium electron spin polarization of a single nitrogen-vacancy center (NV) induced by short laser pulses to the surrounding 13C carbon nuclear spins. The NV is repeatedly repolarized optically, thus providing an effectively infinite polarization reservoir. A saturation of the polarization of the nearby nuclear spins is achieved, which is confirmed by the decay of the polarization transfer signal and shows an excellent agreement with theoretical simulations. Hereby we introduce the polarization readout by polarization inversion method as a quantitative magnetization measure of the nuclear spin bath, which allows us to observe by ensemble averaging macroscopically hidden polarization dynamics like Landau-Zener-Stückelberg oscillations. Moreover, we show that using the integrated solid effect both for single- and double-quantum transitions nuclear spin polarization can be achieved even when the static magnetic field is not aligned along the NV's crystal axis. This opens a path for the application of our DNP technique to spins in and outside of nanodiamonds, enabling their application as MRI tracers. Furthermore, the methods reported here can be applied to other solid state systems where a central electron spin is coupled to a nuclear spin bath, e.g., phosphor donors in silicon and color centers in silicon carbide.

Probing magnetic order in CuFeO2 through nuclear forward scattering in high magnetic fields

NASA Astrophysics Data System (ADS)

Strohm, C.; Lummen, T. T. A.; Handayani, I. P.; Roth, T.; Detlefs, C.; van der Linden, P. J. E. M.; van Loosdrecht, P. H. M.

2013-08-01

Determining the magnetic order of solids in high magnetic fields is technologically challenging. Here we probe the cascade of magnetic phase transitions in frustrated multiferroic CuFeO2 using nuclear forward scattering (NFS) in pulsed magnetic fields up to 30 T. Our results are in excellent agreement with detailed neutron diffraction experiments, currently limited to 15 T, while providing experimental confirmation of the proposed higher field phases for both H∥c and H⊥c. We thus establish NFS as a valuable tool for spin structure studies in very high fields, both complementing and expanding on the applicability of existing techniques.

Nuclear magnetic shielding in boronlike ions

NASA Astrophysics Data System (ADS)

Volchkova, A. M.; Varentsova, A. S.; Zubova, N. A.; Agababaev, V. A.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Plunien, G.

2017-10-01

The relativistic treatment of the nuclear magnetic shielding effect in boronlike ions is presented. The leading-order contribution of the magnetic-dipole hyperfine interaction is calculated. Along with the standard second-order perturbation theory expression, the solutions of the Dirac equation in the presence of magnetic field are employed. All methods are found to be in agreement with each other and with the previous calculations for hydrogenlike and lithiumlike ions. The effective screening potential is used to account approximately for the interelectronic interaction.

Nuclear magnetic resonance data of C36H30Br2OSb2

NASA Astrophysics Data System (ADS)

Mikhova, B. M.

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Nuclear magnetic resonance data of C36H30Cl2OSb2

NASA Astrophysics Data System (ADS)

Mikhova, B. M.

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Nuclear Spin Nanomagnet in an Optically Excited Quantum Dot

NASA Astrophysics Data System (ADS)

Korenev, V. L.

2007-12-01

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins—the nuclear spin nanomagnet.

Nuclear spin nanomagnet in an optically excited quantum dot.

PubMed

Korenev, V L

2007-12-21

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins-the nuclear spin nanomagnet.

Direct current superconducting quantum interference device spectrometer for pulsed nuclear magnetic resonance and nuclear quadrupole resonance at frequencies up to 5 MHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

TonThat, D.M.; Clarke, J.

1996-08-01

A spectrometer based on a dc superconducting quantum interference device (SQUID) has been developed for the direct detection of nuclear magnetic resonance (NMR) or nuclear quadrupole resonance (NQR) at frequencies up to 5 MHz. The sample is coupled to the input coil of the niobium-based SQUID via a nonresonant superconducting circuit. The flux locked loop involves the direct offset integration technique with additional positive feedback in which the output of the SQUID is coupled directly to a low-noise preamplifier. Precession of the nuclear quadrupole spins is induced by a magnetic field pulse with the feedback circuit disabled; subsequently, flux lockedmore » operation is restored and the SQUID amplifies the signal produced by the nuclear free induction signal. The spectrometer has been used to detect {sup 27}Al NQR signals in ruby (Al{sub 2}O{sub 3}[Cr{sup 3+}]) at 359 and 714 kHz. {copyright} {ital 1996 American Institute of Physics.}« less

High field hyperpolarization-EXSY experiment for fast determination of dissociation rates in SABRE complexes

NASA Astrophysics Data System (ADS)

Hermkens, Niels K. J.; Feiters, Martin C.; Rutjes, Floris P. J. T.; Wijmenga, Sybren S.; Tessari, Marco

2017-03-01

SABRE (Signal Amplification By Reversible Exchange) is a nuclear spin hyperpolarization technique based on the reversible concurrent binding of small molecules and para-hydrogen (p-H2) to an iridium metal complex in solution. At low magnetic field, spontaneous conversion of p-H2 spin order to enhanced longitudinal magnetization of the nuclear spins of the other ligands occurs. Subsequent complex dissociation results in hyperpolarized substrate molecules in solution. The lifetime of this complex plays a crucial role in attained SABRE NMR signal enhancements. Depending on the ligands, vastly different dissociation rates have been previously measured using EXSY or selective inversion experiments. However, both these approaches are generally time-consuming due to the long recycle delays (up to 2 min) necessary to reach thermal equilibrium for the nuclear spins of interest. In the cases of dilute solutions, signal averaging aggravates the problem, further extending the experimental time. Here, a new approach is proposed based on coherent hyperpolarization transfer to substrate protons in asymmetric complexes at high magnetic field. We have previously shown that such asymmetric complexes are important for application of SABRE to dilute substrates. Our results demonstrate that a series of high sensitivity EXSY spectra can be collected in a short experimental time thanks to the NMR signal enhancement and much shorter recycle delay.

Restricted lithium ion dynamics in PEO-based block copolymer electrolytes measured by high-field nuclear magnetic resonance relaxation

NASA Astrophysics Data System (ADS)

Huynh, Tan Vu; Messinger, Robert J.; Sarou-Kanian, Vincent; Fayon, Franck; Bouchet, Renaud; Deschamps, Michaël

2017-10-01

The intrinsic ionic conductivity of polyethylene oxide (PEO)-based block copolymer electrolytes is often assumed to be identical to the conductivity of the PEO homopolymer. Here, we use high-field 7Li nuclear magnetic resonance (NMR) relaxation and pulsed-field-gradient (PFG) NMR diffusion measurements to probe lithium ion dynamics over nanosecond and millisecond time scales in PEO and polystyrene (PS)-b-PEO-b-PS electrolytes containing the lithium salt LiTFSI. Variable-temperature longitudinal (T1) and transverse (T2) 7Li NMR relaxation rates were acquired at three magnetic field strengths and quantitatively analyzed for the first time at such fields, enabling us to distinguish two characteristic time scales that describe fluctuations of the 7Li nuclear electric quadrupolar interaction. Fast lithium motions [up to O (ns)] are essentially identical between the two polymer electrolytes, including sub-nanosecond vibrations and local fluctuations of the coordination polyhedra between lithium and nearby oxygen atoms. However, lithium dynamics over longer time scales [O (10 ns) and greater] are slower in the block copolymer compared to the homopolymer, as manifested experimentally by their different transverse 7Li NMR relaxation rates. Restricted dynamics and altered thermodynamic behavior of PEO chains anchored near PS domains likely explain these results.

Application of spin-exchange relaxation-free magnetometry to the Cosmic Axion Spin Precession Experiment

NASA Astrophysics Data System (ADS)

Wang, Tao; Kimball, Derek F. Jackson; Sushkov, Alexander O.; Aybas, Deniz; Blanchard, John W.; Centers, Gary; Kelley, Sean R. O.'; Wickenbrock, Arne; Fang, Jiancheng; Budker, Dmitry

2018-03-01

The Cosmic Axion Spin Precession Experiment (CASPEr) seeks to measure oscillating torques on nuclear spins caused by axion or axion-like-particle (ALP) dark matter via nuclear magnetic resonance (NMR) techniques. A sample spin-polarized along a leading magnetic field experiences a resonance when the Larmor frequency matches the axion/ALP Compton frequency, generating precessing transverse nuclear magnetization. Here we demonstrate a Spin-Exchange Relaxation-Free (SERF) magnetometer with sensitivity ≈ 1 fT /√{ Hz } and an effective sensing volume of 0.1 cm3 that may be useful for NMR detection in CASPEr. A potential drawback of SERF-magnetometer-based NMR detection is the SERF's limited dynamic range. Use of a magnetic flux transformer to suppress the leading magnetic field is considered as a potential method to expand the SERF's dynamic range in order to probe higher axion/ALP Compton frequencies.

Parahydrogen-enhanced zero-field nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Theis, T.; Ganssle, P.; Kervern, G.; Knappe, S.; Kitching, J.; Ledbetter, M. P.; Budker, D.; Pines, A.

2011-07-01

Nuclear magnetic resonance, conventionally detected in magnetic fields of several tesla, is a powerful analytical tool for the determination of molecular identity, structure and function. With the advent of prepolarization methods and detection schemes using atomic magnetometers or superconducting quantum interference devices, interest in NMR in fields comparable to the Earth's magnetic field and below (down to zero field) has been revived. Despite the use of superconducting quantum interference devices or atomic magnetometers, low-field NMR typically suffers from low sensitivity compared with conventional high-field NMR. Here we demonstrate direct detection of zero-field NMR signals generated through parahydrogen-induced polarization, enabling high-resolution NMR without the use of any magnets. The sensitivity is sufficient to observe spectra exhibiting 13C-1H scalar nuclear spin-spin couplings (known as J couplings) in compounds with 13C in natural abundance, without the need for signal averaging. The resulting spectra show distinct features that aid chemical fingerprinting.

Time domain-nuclear magnetic resonance study of chars from southern hardwoods

Treesearch

Thomas Elder; Nicole Labbe; David Harper; Timothy Rials

2006-01-01

Chars from the thermal degradation of silver maple (Acer saccharinum), red maple (Acer rubrum), sugar maple (Acer saccharum), and white oak (Quercus spp.), performed at temperatures from 250 to 350 oC, were examined using time domain-nuclear magnetic resonance...

Discrete decoding based ultrafast multidimensional nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Wei, Zhiliang; Lin, Liangjie; Ye, Qimiao; Li, Jing; Cai, Shuhui; Chen, Zhong

2015-07-01

The three-dimensional (3D) nuclear magnetic resonance (NMR) spectroscopy constitutes an important and powerful tool in analyzing chemical and biological systems. However, the abundant 3D information arrives at the expense of long acquisition times lasting hours or even days. Therefore, there has been a continuous interest in developing techniques to accelerate recordings of 3D NMR spectra, among which the ultrafast spatiotemporal encoding technique supplies impressive acquisition speed by compressing a multidimensional spectrum in a single scan. However, it tends to suffer from tradeoffs among spectral widths in different dimensions, which deteriorates in cases of NMR spectroscopy with more dimensions. In this study, the discrete decoding is proposed to liberate the ultrafast technique from tradeoffs among spectral widths in different dimensions by focusing decoding on signal-bearing sites. For verifying its feasibility and effectiveness, we utilized the method to generate two different types of 3D spectra. The proposed method is also applicable to cases with more than three dimensions, which, based on the experimental results, may widen applications of the ultrafast technique.

Study of the method of water-injected meat identifying based on low-field nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Xu, Jianmei; Lin, Qing; Yang, Fang; Zheng, Zheng; Ai, Zhujun

2018-01-01

The aim of this study to apply low-field nuclear magnetic resonance technique was to study regular variation of the transverse relaxation spectral parameters of water-injected meat with the proportion of water injection. Based on this, the method of one-way ANOVA and discriminant analysis was used to analyse the differences between these parameters in the capacity of distinguishing water-injected proportion, and established a model for identifying water-injected meat. The results show that, except for T 21b, T 22e and T 23b, the other parameters of the T 2 relaxation spectrum changed regularly with the change of water-injected proportion. The ability of different parameters to distinguish water-injected proportion was different. Based on S, P 22 and T 23m as the prediction variable, the Fisher model and the Bayes model were established by discriminant analysis method, qualitative and quantitative classification of water-injected meat can be realized. The rate of correct discrimination of distinguished validation and cross validation were 88%, the model was stable.

Fingerprinting analysis of Rhizoma chuanxiong of commercial types using 1H nuclear magnetic resonance spectroscopy and high performance liquid chromatography method.

PubMed

Qin, Hai-Lin; Deng, An-Jun; Du, Guan-Hua; Wang, Peng; Zhang, Jin-Lan; Li, Zhi-Hong

2009-06-01

The (1)H nuclear magnetic resonance ((1)H NMR) fingerprints of fractionated non-polar extracts (control substance for a plant drug (CSPD) A) from Rhizoma chuanxiong, the rhizomes of Ligusticum chuanxiong Hort., of seven specimens from different sources were measured on Fourier Transform (FT)-NMR spectrometer and assigned by comparing them with the (1)H NMR spectra of the isolated pure compounds. The (1)H NMR fingerprints showed exclusively characteristic resonance signals of the major special constituents of the plant. Although the differences in the relative intensity of the (1)H NMR signals due to a discrepancy in the ratio of the major constituents among these samples could be confirmed by high performance liquid chromatography analysis, the general features of the (1)H NMR fingerprint established for an authentic sample of the rhizomes of L. chuanxiong exhibited exclusive data from those special compounds and can be used for authenticating L. Chuanxiong species.

Alveolar air-tissue interface and nuclear magnetic resonance behavior of the lung

NASA Astrophysics Data System (ADS)

Cutillo, Antonio G.; Ailion, David C.; Ganesan, Krishnamurthy; Morris, Alan H.; Durney, Carl H.

1995-05-01

The nuclear magnetic resonance (NMR) properties of lung are markedly affected by the alveolar air-tissue interface, which produces internal magnetic field inhomogeneity because of the different magnetic susceptibilities of air and water. This internal magnetic field inhomogeneity results in a marked shortening of the free induction decay (FID) (in the time domain) and in inhomogeneous NMR line broadening (in the frequency domain). The signal loss due to internal magnetic field inhomogeneity can be measured as the difference Δ between the spin-echo signals obtained using temporally symmetric and asymmetric spin-echo sequences; the degree of asymmetry of the asymmetric sequence is characterized by the asymmetry time τa. In accordance with predictions based on the analysis of theoretical models, experiments in excised rat lungs (studied at various inflation levels) have shown that Δ depends on τa and is very low in degassed lungs. When measured at τa equals 6 ms, the difference signal (Δ6ms) increases markedly with alveolar opening but does not vary significantly during the rest of the inflation-deflation cycle. In edematous (oleic acid-injured) lungs, the values of Δ6ms measured at low inflation levels are significantly below those observed in normal lungs. These results suggest that Δ6ms is very sensitive to alveolar recruitment and relatively insensitive to alveolar distension. Therefore, measurements of Δ6ms may provide a means of assessing the relative contributions of these two factors to the pressure-volume behavior of lung. Such measurements may contribute to the characterization of pulmonary edema (for example, by detecting the loss of alveolar air-tissue interface due to alveolar flooding, by differentiating interstitial from alveolar pulmonary edema, and by assessing the effects of positive airway pressures). NMR lineshape measurements can also provide valuable information regarding lung geometry and the characterization of pulmonary edema.

Nuclear magnetic moment of {sup 69}As from on-line {beta}-NMR on oriented nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golovko, V.V.; Kraev, I.S.; Phalet, T.

2005-12-15

A precise value for the magnetic moment of the {sup 69}As 5/2{sup -} ground state has been obtained from nuclear magnetic resonance on oriented nuclei (NMR/ON) using the NICOLE {sup 3}He-{sup 4}He dilution refrigerator setup at ISOLDE/CERN. The NMR/ON signal was observed by monitoring the anisotropy of the {sup 69}As {beta} particles. The center frequency {nu}[B{sub ext}=0.0994(10)T]=169.98(9) MHz corresponds to {mu}[{sup 69}As]=+1.6229(16){mu}{sub N}. This result differs considerably from the {pi}f{sub 5/2} single-particle value obtained with g factors for a free proton but is in reasonable agreement with the value obtained with effective g factors and with values from a coremore » polarization calculation and from calculations in the framework of the interacting boson-fermion model. Assuming a single exponential spin-lattice relaxation behavior a relaxation time T{sub 1}{sup '}=10(25) s was observed for {sup 69}AsFe{sub -bar} at a temperature of about 20 mK in a magnetic field B=0.1 T.« less

Atomic magnetic gradiometer for room temperature high sensitivity magnetic field detection

DOEpatents

Xu, Shoujun [Berkeley, CA; Lowery, Thomas L [Belmont, MA; Budker, Dmitry [El Cerrito, CA; Yashchuk, Valeriy V [Richmond, CA; Wemmer, David E [Berkeley, CA; Pines, Alexander [Berkeley, CA

2009-08-11

A laser-based atomic magnetometer (LBAM) apparatus measures magnetic fields, comprising: a plurality of polarization detector cells to detect magnetic fields; a laser source optically coupled to the polarization detector cells; and a signal detector that measures the laser source after being coupled to the polarization detector cells, which may be alkali cells. A single polarization cell may be used for nuclear magnetic resonance (NMR) by prepolarizing the nuclear spins of an analyte, encoding spectroscopic and/or spatial information, and detecting NMR signals from the analyte with a laser-based atomic magnetometer to form NMR spectra and/or magnetic resonance images (MRI). There is no need of a magnetic field or cryogenics in the detection step, as it is detected through the LBAM.

Nuclear Magnetic Resonance Technology for Medical Studies.

ERIC Educational Resources Information Center

Budinger, Thomas F.; Lauterbur, Paul C.

1984-01-01

Reports on the status of nuclear magnetic resonance (NMR) from theoretical and clinical perspectives, reviewing NMR theory and relaxation parameters relevant to NMR imaging. Also reviews literature related to modern imaging strategies, signal-to-noise ratio, contrast agents, in vivo spectroscopy, spectroscopic imaging, clinical applications, and…

COMPREHENSIVE PROGRESS REPORT FOR FOURIER TRANSFORM NMR (NUCLEAR MAGNETIC RESONANCE) OF METALS OF ENVIRONMENTAL SIGNIFICANCE

EPA Science Inventory

Interactions of the metals cadmium and selenium with various biologically important substrates were studied by nuclear magnetic resonance (NMR) spectroscopy. Cadmium-113 NMR was used for a critical examination of three metalloproteins: concanavalin A, bovine superoxide dismutase ...

Dynamic Nuclear Polarization and other magnetic ideas at EPFL.

PubMed

Bornet, Aurélien; Milani, Jonas; Wang, Shutao; Mammoli, Daniele; Buratto, Roberto; Salvi, Nicola; Segaw, Takuya F; Vitzthum, Veronika; Miéville, Pascal; Chinthalapalli, Srinivas; Perez-Linde, Angel J; Carnevale, Diego; Jannin, Sami; Caporinia, Marc; Ulzega, Simone; Rey, Martial; Bodenhausen, Geoffrey

2012-01-01

Although nuclear magnetic resonance (NMR) can provide a wealth of information, it often suffers from a lack of sensitivity. Dynamic Nuclear Polarization (DNP) provides a way to increase the polarization and hence the signal intensities in NMR spectra by transferring the favourable electron spin polarization of paramagnetic centres to the surrounding nuclear spins through appropriate microwave irradiation. In our group at EPFL, two complementary DNP techniques are under investigation: the combination of DNP with magic angle spinning at temperatures near 100 K ('MAS-DNP'), and the combination of DNP at 1.2 K with rapid heating followed by the transfer of the sample to a high-resolution magnet ('dissolution DNP'). Recent applications of MAS-DNP to surfaces, as well as new developments of magnetization transfer of (1)H to (13)C at 1.2 K prior to dissolution will illustrate the work performed in our group. A second part of the paper will give an overview of some 'non-enhanced' activities of our laboratory in liquid- and solid-state NMR.

Calculations of atomic magnetic nuclear shielding constants based on the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Yoshizawa, Terutaka; Zou, Wenli; Cremer, Dieter

2017-04-01

A new method for calculating nuclear magnetic resonance shielding constants of relativistic atoms based on the two-component (2c), spin-orbit coupling including Dirac-exact NESC (Normalized Elimination of the Small Component) approach is developed where each term of the diamagnetic and paramagnetic contribution to the isotropic shielding constant σi s o is expressed in terms of analytical energy derivatives with regard to the magnetic field B and the nuclear magnetic moment 𝝁 . The picture change caused by renormalization of the wave function is correctly described. 2c-NESC/HF (Hartree-Fock) results for the σiso values of 13 atoms with a closed shell ground state reveal a deviation from 4c-DHF (Dirac-HF) values by 0.01%-0.76%. Since the 2-electron part is effectively calculated using a modified screened nuclear shielding approach, the calculation is efficient and based on a series of matrix manipulations scaling with (2M)3 (M: number of basis functions).

Magnetic spin structure and magnetoelectric coupling in BiFeO{sub 3}-BaTiO{sub 3} multilayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazenka, Vera, E-mail: Vera.Lazenka@fys.kuleuven.be; Modarresi, Hiwa; Bisht, Manisha

2015-02-23

Magnetic spin structures in epitaxial BiFeO{sub 3} single layer and an epitaxial BaTiO{sub 3}/BiFeO{sub 3} multilayer thin film have been studied by means of nuclear resonant scattering of synchrotron radiation. We demonstrate a spin reorientation in the 15 × [BaTiO{sub 3}/BiFeO{sub 3}] multilayer compared to the single BiFeO{sub 3} thin film. Whereas in the BiFeO{sub 3} film, the net magnetic moment m{sup →} lies in the (1–10) plane, identical to the bulk, m{sup →} in the multilayer points to different polar and azimuthal directions. This spin reorientation indicates that strain and interfaces play a significant role in tuning the magnetic spin order.more » Furthermore, large difference in the magnetic field dependence of the magnetoelectric coefficient observed between the BiFeO{sub 3} single layer and multilayer can be associated with this magnetic spin reorientation.« less

Complementary Electromagnetic Non-Destructive Evaluation

NASA Astrophysics Data System (ADS)

Tian, Gui Yun; Wilson, John; Morozov, Maxim

2011-06-01

The use of non-destructive evaluation (NDE) for defect detection and failure prediction in structures and specimens is widespread in energy industries, aimed at ageing power plants and pipelines, material degradation, fatigue and radiation damage, etc. At present there are no suitable electromagnetic NDE methods for the measurement and characterization of material degradation, in irradiated samples in particular, which is very important and timely for the nuclear power industry in the UK. This paper reports recent developments in the field of electromagnetic (EM) NDE at Newcastle University, including pulsed eddy current (PEC), pulsed magnetic flux leakage (PMFL), magnetic Barkhausen emission (MBE) and magneto-acoustic emission (MAE). As different EM methods have different strengths, an integrative EM framework is introduced. Case studies through the second round robin tests organized by the Universal Network for Magnetic Non-Destructive Evaluation (UNMNDE), representing eighteen leading research groups worldwide in the area of electromagnetic NDE, are reported. Twelve samples with different ageing times and rolling reduction ratios were tested using different magnetic methods among the UNMNDE members. Based on the studies, the complementary characteristics of electromagnetic techniques for NDE are discussed.

A compact, high temperature nuclear magnetic resonance probe for use in a narrow-bore superconducting magnet

NASA Astrophysics Data System (ADS)

Adler, Stuart B.; Michaels, James N.; Reimer, Jeffrey A.

1990-11-01

The design of a nuclear magnetic resonance (NMR) probe is reported, that can be used in narrow-bore superconducting solenoids for the observation of nuclear induction at high temperatures. The probe is compact, highly sensitive, and stable in continuous operation at temperatures up to 1050 C. The essential feature of the probe is a water-cooled NMR coil that contains the sample-furnace; this design maximizes sensitivity and circuit stability by maintaining the probe electronics at ambient temperature. The design is demonstrated by showing high temperature O-17 NMR spectra and relaxation measurements in solid barium bismuth oxide and yttria-stabilized zirconia.

Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

DOEpatents

Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

2014-01-21

A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

Heart MRI

MedlinePlus

Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

Nanoscale NMR spectroscopy and imaging of multiple nuclear species.

PubMed

DeVience, Stephen J; Pham, Linh M; Lovchinsky, Igor; Sushkov, Alexander O; Bar-Gill, Nir; Belthangady, Chinmay; Casola, Francesco; Corbett, Madeleine; Zhang, Huiliang; Lukin, Mikhail; Park, Hongkun; Yacoby, Amir; Walsworth, Ronald L

2015-02-01

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple nuclear species in bulk matter, with wide-ranging applications from basic physics and chemistry to biomedical imaging. However, the spatial resolution of conventional NMR and MRI is limited to several micrometres even at large magnetic fields (>1 T), which is inadequate for many frontier scientific applications such as single-molecule NMR spectroscopy and in vivo MRI of individual biological cells. A promising approach for nanoscale NMR and MRI exploits optical measurements of nitrogen-vacancy (NV) colour centres in diamond, which provide a combination of magnetic field sensitivity and nanoscale spatial resolution unmatched by any existing technology, while operating under ambient conditions in a robust, solid-state system. Recently, single, shallow NV centres were used to demonstrate NMR of nanoscale ensembles of proton spins, consisting of a statistical polarization equivalent to ∼100-1,000 spins in uniform samples covering the surface of a bulk diamond chip. Here, we realize nanoscale NMR spectroscopy and MRI of multiple nuclear species ((1)H, (19)F, (31)P) in non-uniform (spatially structured) samples under ambient conditions and at moderate magnetic fields (∼20 mT) using two complementary sensor modalities.

Electric field effects on nuclear magnetic shielding of the 1:1 and 2:1 (homo and heterochiral) complexes of XOOX' (X, X' = H, CH3) with lithium cation and their chiral discrimination.

PubMed

Alkorta, Ibon; Elguero, José; Provasi, Patricio F; Pagola, Gabriel I; Ferraro, Marta B

2011-09-14

The set of 1:1 and 2:1 complexes of XOOX' (X, X' = H, CH(3)) with lithium cation has been studied to determine if they are suitable candidates for chiral discrimination in an isotropic medium via nuclear magnetic resonance spectroscopy. Conventional nuclear magnetic resonance is unable to distinguish between enantiomers in the absence of a chiral solvent. The criterion for experimental detection is valuated by the isotropic part of nuclear shielding polarisability tensors, related to a pseudoscalar of opposite sign for two enantiomers. The study includes calculations at coupled Hartree-Fock and density functional theory schemes for (17)O nucleus in each compound. Additional calculations for (1)H are also included for some compounds. A huge static homogeneous electric field, perpendicular to the magnetic field of the spectromer, as big as ≈1.7 × 10(8) V m(-1) should be applied to observe a shift of ≈1 ppm for (17)O magnetic shielding in the proposed set of complexes. © 2011 American Institute of Physics

Computer simulation of magnetic resonance spectra employing homotopy.

PubMed

Gates, K E; Griffin, M; Hanson, G R; Burrage, K

1998-11-01

Multidimensional homotopy provides an efficient method for accurately tracing energy levels and hence transitions in the presence of energy level anticrossings and looping transitions. Herein we describe the application and implementation of homotopy to the analysis of continuous wave electron paramagnetic resonance spectra. The method can also be applied to electron nuclear double resonance, electron spin echo envelope modulation, solid-state nuclear magnetic resonance, and nuclear quadrupole resonance spectra. Copyright 1998 Academic Press.

Nuclear magnetic resonance studies of ancient buried wood-I. Observations on the origin of coal to the brown coal stage

USGS Publications Warehouse

Hatcher, P.G.; Breger, I.A.; Earl, W.L.

1981-01-01

Various wood fragments buried in sediments under anaerobic conditions for from 450 yr to approximately 8 Myr have been examined by solid-state 13C nuclear magnetic resonance. Cellulose and other carbohydrates, the major components of Holocene wood, have been shown to be gradually hydrolyzed or otherwise lost under the conditions of burial. Lignin structures, however, are preserved relatively unchanged and become concentrated by difference as the carbohydrates disappear. Thus, a fragment of coalified wood isolated from a Miocene brown coal was found to be still composed of approximately 75% lignin and 25% cellulose. On the basis of our observations, we suggest that coalification of woody tissue progresses directly from lignin to coal and that such coalification may be retarded until most of the cellulose disappears. ?? 1981.

[The water content reference material of water saturated octanol].

PubMed

Wang, Haifeng; Ma, Kang; Zhang, Wei; Li, Zhanyuan

2011-03-01

The national standards of biofuels specify the technique specification and analytical methods. A water content certified reference material based on the water saturated octanol was developed in order to satisfy the needs of the instrument calibration and the methods validation, assure the accuracy and consistency of results in water content measurements of biofuels. Three analytical methods based on different theories were employed to certify the water content of the reference material, including Karl Fischer coulometric titration, Karl Fischer volumetric titration and quantitative nuclear magnetic resonance. The consistency of coulometric and volumetric titration was achieved through the improvement of methods. The accuracy of the certified result was improved by the introduction of the new method of quantitative nuclear magnetic resonance. Finally, the certified value of reference material is 4.76% with an expanded uncertainty of 0.09%.

An Accessible Two-Dimensional Solution Nuclear Magnetic Resonance Experiment on Human Ubiquitin

ERIC Educational Resources Information Center

Rovnyak, David; Thompson, Laura E.

2005-01-01

Solution-state nuclear magnetic resonance (NMR) is an invaluable tool in structural and molecular biology research, but may be underutilized in undergraduate laboratories because instrumentation for performing structural studies of macromolecules in aqueous solutions is not yet widely available for use in undergraduate laboratories. We have…

Quantitative Analysis of Nail Polish Remover Using Nuclear Magnetic Resonance Spectroscopy Revisited

ERIC Educational Resources Information Center

Hoffmann, Markus M.; Caccamis, Joshua T.; Heitz, Mark P.; Schlecht, Kenneth D.

2008-01-01

Substantial modifications are presented for a previously described experiment using nuclear magnetic resonance (NMR) spectroscopy to quantitatively determine analytes in commercial nail polish remover. The revised experiment is intended for a second- or third-year laboratory course in analytical chemistry and can be conducted for larger laboratory…

Molecular nanomagnets: Syntheses and characterization of high nuclearity transition metal complexes

NASA Astrophysics Data System (ADS)

Foguet-Albiol, Maria D.

2006-12-01

High nuclearity transition metal complexes have attracted a lot of attention because of their aesthetically pleasant structures and/or their potential applications. The fusion of the world of magnetism with the exciting research in physics and chemistry led to the realization of interesting types of materials that can function as nanoscale magnetic particles. The study of the magnetism of inorganic complexes and especially the study of these molecular nanomagnets (or single-molecule magnets, SMMs) is a field that has generated intense interest in the scientific community. Interest in these molecular nanomagnets arises as part of a broader investigation of nanomagnetism (and nanotechnology), as these represent the ultimate step in device miniaturization. The primary purpose of this dissertation is the development of new synthetic methods intended for the preparation of novel single-molecule magnets (SMMs). The definition of the "bottom-up approach" is to increase the size of molecules by adding new magnetic centers; this is attractive but does not actually reflect how the chemistry takes place. Various strategies have been employed in developing the aforementioned synthetic methods which include the use of mononuclear as well as preformed clusters as starting materials; and the introduction of new alcohol based ligands as N-methyldiethanolamine (mdaH2) and triethanolamine (teaH3), since currently only a few alcohol based ligands have been used by different research groups. Many of these efforts have led to the isolation of new polynuclear Mn clusters with nuclearities ranging all the way from four to thirty-one. Additionally, a family of related Fe7 complexes has been synthesized. The transition metal cluster chemistry has also been extended to nickel-containing species. Many of these polynulear transition metal complexes function as single-molecule magnets. An additional research direction discussed herein is the study of the exchange-coupled dimer of single-molecule magnets (SMMs) by previously unemployed techniques (i.e., inelastic neutron scattering (INS)). This latter study resulted in a better understanding of the effects of chemical and physical variations on the magnetic parameters S, D and J. These studies provide insight into approaches necessary to gain access to clusters that behave as single-molecule magnets at more technologically relevant temperatures, an issue of growing concern as the research area further matures.

Tensor of effective susceptibility in random magnetic composites: Application to two-dimensional and three-dimensional cases

NASA Astrophysics Data System (ADS)

Posnansky, Oleg P.

2018-05-01

The measuring of dynamic magnetic susceptibility by nuclear magnetic resonance is used for revealing information about the internal structure of various magnetoactive composites. The response of such material on the applied external static and time-varying magnetic fields encodes intrinsic dynamic correlations and depends on links between macroscopic effective susceptibility and structure on the microscopic scale. In the current work we carried out computational analysis of the frequency dependent dynamic magnetic susceptibility and demonstrated its dependence on the microscopic architectural elements while also considering Euclidean dimensionality. The proposed numerical method is efficient in the simulation of nuclear magnetic resonance experiments in two- and three-dimensional random magnetic media by choosing and modeling the influence of the concentration of components and internal hierarchical characteristics of physical parameters.

Voltage-selective bidirectional polarization and coherent rotation of nuclear spins in quantum dots.

PubMed

Takahashi, R; Kono, K; Tarucha, S; Ono, K

2011-07-08

We propose and demonstrate that the nuclear spins of the host lattice in GaAs double quantum dots can be polarized in either of two opposite directions, parallel or antiparallel to an external magnetic field. The direction is selected by adjusting the dc voltage. This nuclear polarization manifests itself by repeated controlled electron-nuclear spin scattering in the Pauli spin-blockade state. Polarized nuclei are also controlled by means of nuclear magnetic resonance. This Letter confirms that the nuclear spins in quantum dots are long-lived quantum states with a coherence time of up to 1 ms, and may be a promising resource for quantum-information processing such as quantum memories for electron spin qubits.

Magnetic Analyzer Mavr for Study of Exotic Weakly Bound Nuclei

NASA Astrophysics Data System (ADS)

Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

2015-06-01

A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ~1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400 - U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

Study of Exotic Weakly Bound Nuclei Using Magnetic Analyzer Mavr

NASA Astrophysics Data System (ADS)

Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

2016-06-01

A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ∼1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400 - U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

Electromagnetic nonlinearities in a Roebel-cable-based accelerator magnet prototype: variational approach

NASA Astrophysics Data System (ADS)

Ruuskanen, J.; Stenvall, A.; Lahtinen, V.; Pardo, E.

2017-02-01

Superconducting magnets are the most expensive series of components produced in the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN). When developing such magnets beyond state-of-the-art technology, one possible option is to use high-temperature superconductors (HTS) that are capable of tolerating much higher magnetic fields than low-temperature superconductors (LTS), carrying simultaneously high current densities. Significant cost reductions due to decreased prototype construction needs can be achieved by careful modelling of the magnets. Simulations are used, e.g. for designing magnets fulfilling the field quality requirements of the beampipe, and adequate protection by studying the losses occurring during charging and discharging. We model the hysteresis losses and the magnetic field nonlinearity in the beampipe as a function of the magnet’s current. These simulations rely on the minimum magnetic energy variation principle, with optimization algorithms provided by the open-source optimization library interior point optimizer. We utilize this methodology to investigate a research and development accelerator magnet prototype made of REBCO Roebel cable. The applicability of this approach, when the magnetic field dependence of the superconductor’s critical current density is considered, is discussed. We also scrutinize the influence of the necessary modelling decisions one needs to make with this approach. The results show that different decisions can lead to notably different results, and experiments are required to study the electromagnetic behaviour of such magnets further.

The effect of static magnetic fields and tat peptides on cellular and nuclear uptake of magnetic nanoparticles.

PubMed

Smith, Carol-Anne M; de la Fuente, Jesus; Pelaz, Beatriz; Furlani, Edward P; Mullin, Margaret; Berry, Catherine C

2010-05-01

Magnetic nanoparticles are widely used in bioapplications such as imaging (MRI), targeted delivery (drugs/genes) and cell transfection (magnetofection). Historically, the impermeable nature of both the plasma and nuclear membranes hinder potential. Researchers combat this by developing techniques to enhance cellular and nuclear uptake. Two current popular methods are using external magnetic fields to remotely control particle direction or functionalising the nanoparticles with a cell penetrating peptide (e.g. tat); both of which facilitate cell entry. This paper compares the success of both methods in terms of nanoparticle uptake, analysing the type of magnetic forces the particles experience, and determines gross cell response in terms of morphology and structure and changes at the gene level via microarray analysis. Results indicated that both methods enhanced uptake via a caveolin dependent manner, with tat peptide being the more efficient and achieving nuclear uptake. On comparison to control cells, many groups of gene changes were observed in response to the particles. Importantly, the magnetic field also caused many change in gene expression, regardless of the nanoparticles, and appeared to cause F-actin alignment in the cells. Results suggest that static fields should be modelled and analysed prior to application in culture as cells clearly respond appropriately. Furthermore, the use of cell penetrating peptides may prove more beneficial in terms of enhancing uptake and maintaining cell homeostasis than a magnetic field. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves.

PubMed

Thurber, Kent R; Tycko, Robert

2014-05-14

We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

Dynamical Nuclear Magnetic Resonance Imaging of Micron-scale Liquids

NASA Astrophysics Data System (ADS)

Sixta, Aimee; Choate, Alexandra; Maeker, Jake; Bogat, Sophia; Tennant, Daniel; Mozaffari, Shirin; Markert, John

We report our efforts in the development of Nuclear Magnetic Resonance Force Microscopy (NMRFM) for dynamical imaging of liquid media at the micron scale. Our probe contains microfluidic samples sealed in thin-walled (µm) quartz tubes, with a micro-oscillator sensor nearby in vacuum to maintain its high mechanical resonance quality factor. Using 10 µm spherical permalloy magnets at the oscillator tips, a 3D T1-resolved image of spin density can be obtained by reconstruction from our magnetostatics-modelled resonance slices; as part of this effort, we are exploring single-shot T1 measurements for faster dynamical imaging. We aim to further enhance imaging by using a 2 ω technique to eliminate artifact signals during the cyclic inversion of nuclear spins. The ultimate intent of these efforts is to perform magnetic resonance imaging of individual biological cells.

A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)

NASA Astrophysics Data System (ADS)

Garbacz, Piotr; Fischer, Peer; Krämer, Steffen

2016-09-01

Direct detection of molecular chirality is practically impossible by methods of standard nuclear magnetic resonance (NMR) that is based on interactions involving magnetic-dipole and magnetic-field operators. However, theoretical studies provide a possible direct probe of chirality by exploiting an enantiomer selective additional coupling involving magnetic-dipole, magnetic-field, and electric field operators. This offers a way for direct experimental detection of chirality by nuclear magneto-electric resonance (NMER). This method uses both resonant magnetic and electric radiofrequency (RF) fields. The weakness of the chiral interaction though requires a large electric RF field and a small transverse RF magnetic field over the sample volume, which is a non-trivial constraint. In this study, we present a detailed study of the NMER concept and a possible experimental realization based on a loop-gap resonator. For this original device, the basic principle and numerical studies as well as fabrication and measurements of the frequency dependence of the scattering parameter are reported. By simulating the NMER spin dynamics for our device and taking the 19F NMER signal of enantiomer-pure 1,1,1-trifluoropropan-2-ol, we predict a chirality induced NMER signal that accounts for 1%-5% of the standard achiral NMR signal.

Spontaneous 15N Nuclear Spin Hyperpolarization in Metal-Free Activation of Parahydrogen by Molecular Tweezers

PubMed Central

2018-01-01

The ability of frustrated Lewis pairs (FLPs) to activate H2 is of significant interest for metal-free catalysis. The activation of H2 is also the key element of parahydrogen-induced polarization (PHIP), one of the nuclear spin hyperpolarization techniques. It is demonstrated that o-phenylene-based ansa-aminoboranes (AABs) can produce 1H nuclear spin hyperpolarization through a reversible interaction with parahydrogen at ambient temperatures. Heteronuclei are useful in NMR and MRI as well because they have a broad chemical shift range and long relaxation times and may act as background-free labels. We report spontaneous formation of 15N hyperpolarization of the N–H site for a family of AABs. The process is efficient at the high magnetic field of an NMR magnet (7 T), and it provides up to 350-fold 15N signal enhancements. Different hyperpolarization effects are observed with various AAB structures and in a broad temperature range. Spontaneous hyperpolarization, albeit an order of magnitude weaker than that for 15N, was also observed for 11B nuclei. PMID:29401399

NMR of (133)Cs(+) in stretched hydrogels: One-dimensional, z- and NOESY spectra, and probing the ion's environment in erythrocytes.

PubMed

Kuchel, Philip W; Shishmarev, Dmitry; Puckeridge, Max; Levitt, Malcolm H; Naumann, Christoph; Chapman, Bogdan E

2015-12-01

(133)Cs nuclear magnetic resonance (NMR) spectroscopy was conducted on (133)Cs(+) in gelatin hydrogels that were either relaxed or stretched. Stretching generated a septet from this spin-7/2 nucleus, and its nuclear magnetic relaxation was studied via z-spectra, and two-dimensional nuclear Overhauser (NOESY) spectroscopy. Various spectral features were well simulated by using Mathematica and the software package SpinDynamica. Spectra of CsCl in suspensions of human erythrocytes embedded in gelatin gel showed separation of the resonances from the cation inside and outside the cells. Upon stretching the sample, the extracellular (133)Cs(+) signal split into a septet, while the intracellular peak was unchanged, revealing different alignment/ordering properties of the environment inside and around the cells. Differential interference contrast light microscopy confirmed that the cells were stretched when the overall sample was elongated. Analysis of the various spectral features of (133)Cs(+) reported here opens up applications of this K(+) congener for studies of cation-handling by metabolically-active cells and tissues in aligned states. Copyright © 2015 Elsevier Inc. All rights reserved.

Coherent manipulation of quantum spin states in a single molecular nanomagnet

NASA Astrophysics Data System (ADS)

Wernsdorfer, Wolfgang

The endeavour of quantum electronics is driven by one of the most ambitious technological goals of today's scientists: the realization of an operational quantum computer (http://qurope.eu). We started to address this goal by the new research field of molecular quantum spintronics. The building blocks are magnetic molecules, i.e. well-defined spin qubits. We will discuss this still largely unexplored field and present our first results: For example, using a molecular spin-transistor, we achieved the electronic read-out of the nuclear spin of an individual metal atom embedded in an SMM. We could show very long spin lifetimes (>10 s). Using the hyperfine Stark effect, which transforms electric fields into local effective magnetic fields, we could not only tune the resonance frequency by several MHz, but also perform coherent quantum manipulations on a single nuclear qubit faster than a μs by means of electrical fields only, establishing the individual addressability of identical nuclear qubits. Using three different microwave frequencies, we could implement a simple four-level Grover algorithm. S. Thiele, F. Balestro, R. Ballou, S. Klyatskaya, M. Ruben, W. Wernsdorfer, Science 344, 1135 (2014).

Diamond nitrogen vacancy electronic and nuclear spin-state anti-crossings under weak transverse magnetic fields

NASA Astrophysics Data System (ADS)

Clevenson, Hannah; Chen, Edward; Dolde, Florian; Teale, Carson; Englund, Dirk; Braje, Danielle

2016-05-01

We report on detailed studies of electronic and nuclear spin states in the diamond nitrogen vacancy (NV) center under moderate transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV ground state hyperfine anti-crossing occurring at magnetic bias fields as low as tens of Gauss - two orders of magnitude lower than previously reported hyperfine anti-crossings at ~ 510 G and ~ 1000 G axial magnetic fields. We then discuss how this regime can be optimized for magnetometry and other sensing applications and propose a method for how the nitrogen-vacancy ground state Hamiltonian can be manipulated by small transverse magnetic fields to polarize the nuclear spin state. Acknowlegement: The Lincoln Laboratory portion of this work is sponsored by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract #FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the authors and are not necessarily endorsed by the United States Government.

Method and apparatus for measuring nuclear magnetic properties

DOEpatents

Weitekamp, D.P.; Bielecki, A.; Zax, D.B.; Zilm, K.W.; Pines, A.

1987-12-01

A method for studying the chemical and structural characteristics of materials is disclosed. The method includes placement of a sample material in a high strength polarizing magnetic field to order the sample nuclei. The condition used to order the sample is then removed abruptly and the ordering of the sample allowed to evolve for a time interval. At the end of the time interval, the ordering of the sample is measured by conventional nuclear magnetic resonance techniques. 5 figs.

Method and apparatus for measuring nuclear magnetic properties

DOEpatents

Weitekamp, Daniel P.; Bielecki, Anthony; Zax, David B.; Zilm, Kurt W.; Pines, Alexander

1987-01-01

A method for studying the chemical and structural characteristics of materials is disclosed. The method includes placement of a sample material in a high strength polarizing magnetic field to order the sample nucleii. The condition used to order the sample is then removed abruptly and the ordering of the sample allowed to evolve for a time interval. At the end of the time interval, the ordering of the sample is measured by conventional nuclear magnetic resonance techniques.

Dynamic nuclear polarization at high Landau levels in a quantum point contact

NASA Astrophysics Data System (ADS)

Fauzi, M. H.; Noorhidayati, A.; Sahdan, M. F.; Sato, K.; Nagase, K.; Hirayama, Y.

2018-05-01

We demonstrate a way to polarize and detect nuclear spin in a gate-defined quantum point contact operating at high Landau levels. Resistively detected nuclear magnetic resonance (RDNMR) can be achieved up to the fifth Landau level and at a magnetic field lower than 1 T. We are able to retain the RDNMR signals in a condition where the spin degeneracy of the first one-dimensional (1D) subband is still preserved. Furthermore, the effects of orbital motion on the first 1D subband can be made smaller than those due to electrostatic confinement. This developed RDNMR technique is a promising means to study electronic states in a quantum point contact near zero magnetic field.

Magnetic nuclear core restraint and control

DOEpatents

Cooper, Martin H.

1979-01-01

A lateral restraint and control system for a nuclear reactor core adaptable to provide an inherent decrease of core reactivity in response to abnormally high reactor coolant fluid temperatures. An electromagnet is associated with structure for radially compressing the core during normal reactor conditions. A portion of the structures forming a magnetic circuit are composed of ferromagnetic material having a curie temperature corresponding to a selected coolant fluid temperature. Upon a selected signal, or inherently upon a preselected rise in coolant temperature, the magnetic force is decreased a given amount sufficient to relieve the compression force so as to allow core radial expansion. The expanded core configuration provides a decreased reactivity, tending to shut down the nuclear reaction.

Magnetic nuclear core restraint and control

DOEpatents

Cooper, Martin H.

1978-01-01

A lateral restraint and control system for a nuclear reactor core adaptable to provide an inherent decrease of core reactivity in response to abnormally high reactor coolant fluid temperatures. An electromagnet is associated with structure for radially compressing the core during normal reactor conditions. A portion of the structures forming a magnetic circuit are composed of ferromagnetic material having a curie temperature corresponding to a selected coolant fluid temperature. Upon a selected signal, or inherently upon a preselected rise in coolant temperature, the magnetic force is decreased a given amount sufficient to relieve the compression force so as to allow core radial expansion. The expanded core configuration provides a decreased reactivity, tending to shut down the nuclear reaction.

Search for variation of fundamental constants and violations of fundamental symmetries using isotope comparisons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berengut, J. C.; Flambaum, V. V.; Kava, E. M.

2011-10-15

Atomic microwave clocks based on hyperfine transitions, such as the caesium standard, tick with a frequency that is proportional to the magnetic moment of the nucleus. This magnetic moment varies strongly between isotopes of the same atom, while all atomic electron parameters remain the same. Therefore the comparison of two microwave clocks based on different isotopes of the same atom can be used to constrain variation of fundamental constants. In this paper, we calculate the neutron and proton contributions to the nuclear magnetic moments, as well as their sensitivity to any potential quark-mass variation, in a number of isotopes ofmore » experimental interest including {sup 201,199}Hg and {sup 87,85}Rb, where experiments are underway. We also include a brief treatment of the dependence of the hyperfine transitions to variation in nuclear radius, which in turn is proportional to any change in quark mass. Our calculations of expectation values of proton and neutron spin in nuclei are also needed to interpret measurements of violations of fundamental symmetries.« less

Level anti-crossings are a key factor for understanding para-hydrogen-induced hyperpolarization in SABRE experiments.

PubMed

Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L; Kaptein, Robert

2013-10-07

Various hyperpolarization methods are able to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) by several orders of magnitude. Among these methods are para-hydrogen-induced polarization (PHIP) and signal amplification by reversible exchange (SABRE), which exploit the strong nuclear alignment of para-hydrogen. Several SABRE experiments have been reported but, so far, it has not been possible to account for the experimentally observed sign and magnetic-field dependence of substrate polarization. Herein, we present an analysis based on level anti-crossings (LACs), which provides a complete understanding of the SABRE effect. The field-dependence of both net and anti-phase polarization is measured for several ligands, which can be reproduced by the theory. The similar SABRE field-dependence for different ligands is also explained. In general, the LAC concept allows complex spin dynamics to be unraveled, and is crucial for optimizing the performance of novel hyperpolarization methods in NMR and MRI techniques. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

PubMed

Afach, S; Ayres, N J; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Griffith, W C; Grujić, Z D; Harris, P G; Heil, W; Hélaine, V; Kasprzak, M; Kermaidic, Y; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Plonka-Spehr, C; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severijns, N; Thorne, J A; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

2015-10-16

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1  μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1  pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

The effects of nuclear magnetic resonance on patients with cardiac pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavlicek, W.; Geisinger, M.; Castle, L.

1983-04-01

The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation in the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to time-varying magnetic fields.

CAKE: the coincidence array for K600 experiments

NASA Astrophysics Data System (ADS)

Adsley, P.; Neveling, R.; Papka, P.; Dyers, Z.; Brümmer, J. W.; Diget, C. Aa.; Hubbard, N. J.; Li, K. C. W.; Long, A.; Marin-Lambarri, D. J.; Pellegri, L.; Pesudo, V.; Pool, L. C.; Smit, F. D.; Triambak, S.

2017-02-01

The combination of a magnetic spectrometer and ancillary detectors such as silicon detectors is a powerful tool for the study of nuclear reactions and nuclear structure. This paper discusses the recently commissioned silicon array called the "CAKE" which is designed for use with the K600 magnetic spectrometer at iThemba LABS.

A Noninvasive Method to Study Regulation of Extracellular Fluid Volume in Rats Using Nuclear Magnetic Resonance

EPA Science Inventory

Time-domain nuclear magnetic resonance (TD-NMR)-based measurement of body composition of rodents is an effective method to quickly and repeatedly measure proportions of fat, lean, and fluid without anesthesia. TD-NMR provides a measure of free water in a living animal, termed % f...

MEMS-based force-detected nuclear magnetic resonance spectrometer for in situ planetary exploration

NASA Technical Reports Server (NTRS)

George, T.; Leskowitz, G.; Madsen, L.; Weitekamp, D.; Tang, W.

2000-01-01

Nuclear Magnetic resonance (NMR) is a well-known spectroscopic technique used by chemists and is especially powerful in detecting the presence of water and distinguishing between arbitrary physisorbed and chemisorbed states. This ability is of particular importance in the search for extra-terrestrial life on planets such as Mars.

Thermal behavior of epoxidized cardanol diethyl phosphate as novel renewable plasticizer for poly(vinyl chloride)

USDA-ARS?s Scientific Manuscript database

A novel plasticizer, epoxidized cardanol diethyl phosphate (ECEP), based on cardanol was synthesized. Chemical structure of ECEP was characterized by fourier transform infrared (FTIR), 1H-nuclear magnetic resonance(1H NMR) and 13C-nuclear magnetic resonance(13C NMR) spectroscopy. Effects of ECEP sub...

The Complexation of the Na(super +) by 18-Crown-6 Studied via Nuclear Magnetic Resonance

ERIC Educational Resources Information Center

Peters, Steven J.; Stevenson, Cheryl D.

2004-01-01

A student friendly experiment that teaches several important concepts of modern nuclear magnetic resonance (NMR), like multinuclear capabilities, the NMR time scale, and time-averaged signals, is described along with some important concepts of thermo chemical equilibria. The mentioned experiment involves safe and inexpensive compounds, such as…

Near-electrode imager

DOEpatents

Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, II, Rex E.

2000-01-01

An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager uses the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

Quantitative nuclear magnetic resonance to measure body composition in infants and children

USDA-ARS?s Scientific Manuscript database

Quantitative Nuclear Magnetic Resonance (QMR) is being used in human adults to obtain measures of total body fat (FM) with high precision. The current study assessed a device specially designed to accommodate infants and children between 3 and 50 kg (EchoMRI-AH™). Body composition of 113 infants and...

Analysis of cocondensation of melamine and urea through carbon 13 enriched formaldehyde with C-13 nuclear magnetic resonance spectroscopy

Treesearch

Bunichiro Tomita; Chung-Yun Hse

1995-01-01

The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-ureaformaldehyde (MUF) cocondensed resins were synthesized using the labeling method with 13C enriched formaldehyde under neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field...

Using Nuclear Magnetic Resonance Spectroscopy for Measuring Ternary Phase Diagrams

ERIC Educational Resources Information Center

Woodworth, Jennifer K.; Terrance, Jacob C.; Hoffmann, Markus M.

2006-01-01

A laboratory experiment is presented for the upper-level undergraduate physical chemistry curriculum in which the ternary phase diagram of water, 1-propanol and n-heptane is measured using proton nuclear magnetic resonance (NMR) spectroscopy. The experiment builds upon basic concepts of NMR spectral analysis, typically taught in the undergraduate…

High field hyperpolarization-EXSY experiment for fast determination of dissociation rates in SABRE complexes.

PubMed

Hermkens, Niels K J; Feiters, Martin C; Rutjes, Floris P J T; Wijmenga, Sybren S; Tessari, Marco

2017-03-01

SABRE (Signal Amplification By Reversible Exchange) is a nuclear spin hyperpolarization technique based on the reversible concurrent binding of small molecules and para-hydrogen (p-H 2 ) to an iridium metal complex in solution. At low magnetic field, spontaneous conversion of p-H 2 spin order to enhanced longitudinal magnetization of the nuclear spins of the other ligands occurs. Subsequent complex dissociation results in hyperpolarized substrate molecules in solution. The lifetime of this complex plays a crucial role in attained SABRE NMR signal enhancements. Depending on the ligands, vastly different dissociation rates have been previously measured using EXSY or selective inversion experiments. However, both these approaches are generally time-consuming due to the long recycle delays (up to 2min) necessary to reach thermal equilibrium for the nuclear spins of interest. In the cases of dilute solutions, signal averaging aggravates the problem, further extending the experimental time. Here, a new approach is proposed based on coherent hyperpolarization transfer to substrate protons in asymmetric complexes at high magnetic field. We have previously shown that such asymmetric complexes are important for application of SABRE to dilute substrates. Our results demonstrate that a series of high sensitivity EXSY spectra can be collected in a short experimental time thanks to the NMR signal enhancement and much shorter recycle delay. Copyright © 2017 Elsevier Inc. All rights reserved.

Early prognostic markers for fatal fulminant hepatic failure cases with viral hepatitis: proton nuclear magnetic resonance spectroscopic studies of serum.

PubMed

Bala, Lakshmi; Mehrotra, Mayank; Mohindra, Samir; Saxena, Rajan; Khetrapal, Chunni Lal

2013-02-01

Fulminant hepatic failure is associated with liver metabolic derangements which could have fatal consequences. The aim of the present study is to identify serum markers for early prediction of the outcome. Proton nuclear magnetic resonance spectroscopic studies of serum of fulminant hepatic failure patients due to viral hepatitis with grade II/III of encephalopathy (twenty-four: ten prospective and fourteen retrospective) and twenty-five controls were undertaken. Of the twenty-four patients, fifteen survived with medical management alone while nine had fatal outcome. The results demonstrated significantly elevated indices of amino acids (alanine, lysine, glutamine, histidine, tyrosine, phenylalanine and 1,2-propanediol) in fatal cases compared to survivors and controls. Principal component analysis showed clear separation of fatal and surviving cases. Liver function parameters were significantly deranged in patients but they failed to provide early significant differences between surviving and fatal cases. Compared to model for end-stage liver disease scores, principal component analysis appear to be better as an early prognostic indicator. Biochemical mapping of pathways suggested interruptions in amino acid metabolism and urea cycle. Proton nuclear magnetic resonance studies of serum have the potential of rapidly identifying patients with irreversible fulminant hepatic failure requiring liver transplantation as life saving option. Copyright © 2012 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

NASA Astrophysics Data System (ADS)

Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

2015-01-01

The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

Electrical detection of nuclear spin-echo signals in an electron spin injection system

NASA Astrophysics Data System (ADS)

Lin, Zhichao; Rasly, Mahmoud; Uemura, Tetsuya

2017-06-01

We demonstrated spin echoes of nuclear spins in a spin injection device with a highly polarized spin source by nuclear magnetic resonance (NMR). Efficient spin injection into GaAs from a half-metallic spin source of Co2MnSi enabled efficient dynamic nuclear polarization (DNP) and sensitive detection of NMR signals even at a low magnetic field of ˜0.1 T and a relatively high temperature of 4.2 K. The intrinsic coherence time T2 of 69Ga nuclear spins was evaluated from the spin-echo signals. The relation between T2 and the decay time of the Rabi oscillation suggests that the inhomogeneous effects in our system are not obvious. This study provides an all-electrical NMR system for nuclear-spin-based qubits.

Recent advances in nuclear magnetic resonance quantum information processing.

PubMed

Criger, Ben; Passante, Gina; Park, Daniel; Laflamme, Raymond

2012-10-13

Quantum information processors have the potential to drastically change the way we communicate and process information. Nuclear magnetic resonance (NMR) has been one of the first experimental implementations of quantum information processing (QIP) and continues to be an excellent testbed to develop new QIP techniques. We review the recent progress made in NMR QIP, focusing on decoupling, pulse engineering and indirect nuclear control. These advances have enhanced the capabilities of NMR QIP, and have useful applications in both traditional NMR and other QIP architectures.

Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath.

PubMed

Morello, A; Millán, A; de Jongh, L J

2014-03-21

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at T ≈ 30 mK in perpendicular fields B⊥ up to 9 T. The relaxation channel at B ≈ 0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for B⊥>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an "effective two-level system" and its surrounding spin bath.

Electrically Driving Donor Spin Qubits in Silicon Using Photonic Bandgap Resonators

NASA Astrophysics Data System (ADS)

Sigillito, A. J.; Tyryshkin, A. M.; Lyon, S. A.

In conventional experiments, donor nuclear spin qubits in silicon are driven using radiofrequency (RF) magnetic fields. However, magnetic fields are difficult to confine at the nanoscale, which poses major issues for individually addressable qubits and device scalability. Ideally one could drive spin qubits using RF electric fields, which are easy to confine, but spins do not naturally have electric dipole transitions. In this talk, we present a new method for electrically controlling nuclear spin qubits in silicon by modulating the hyperfine interaction between the nuclear spin qubit and the donor-bound electron. By fabricating planar superconducting photonic bandgap resonators, we are able to use pulsed electron-nuclear double resonance (ENDOR) techniques to selectively probe both electrically and magnetically driven transitions for 31P and 75As nuclear spin qubits. The electrically driven spin resonance mechanism allows qubits to be driven at either their transition frequency, or at one-half their transition frequency, thus reducing bandwidth requirements for future quantum devices. Moreover, this form of control allows for higher qubit densities and lower power requirements compared to magnetically driven schemes. In our proof-of-principle experiments we demonstrate electrically driven Rabi frequencies of approximately 50 kHz for widely spaced (10 μm) gates which should be extendable to MHz for nanoscale devices.

Calibration of an analyzing magnet using the 12C(d, p0)13C nuclear reaction with a thick carbon target

NASA Astrophysics Data System (ADS)

Andrade, E.; Canto, C. E.; Rocha, M. F.

2017-09-01

The absolute energy of an ion beam produced by an accelerator is usually determined by an electrostatic or magnetic analyzer, which in turn must be calibrated. Various methods for accelerator energy calibration are extensively reported in the literature, like nuclear reaction resonances, neutron threshold, and time of flight, among others. This work reports on a simple method to calibrate the magnet associated to a vertical 5.5 MV Van de Graaff accelerator. The method is based on bombarding with deuteron beams a thick carbon target and measuring with a surface barrier detector the particle energy spectra produced. The analyzer magnetic field is measured for each spectrum and the beam energy is deduced by the best fit of the simulation of the spectrum with the SIMNRA code that includes 12C(d,p0)13C nuclear cross sections.

Volovik effect and Fermi-liquid behavior in the s -wave superconductor CaPd 2 As 2 :   As 75 NMR-NQR measurements

DOE PAGES

Ding, Q. -P.; Wiecki, P.; Anand, V. K.; ...

2016-04-07

The electronic and magnetic properties of the collapsed-tetragonal CaPd 2As 2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T 1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/T 1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below T c and decreases exponentially at lower T, confirming a conventional s-wave SC. Additionally, the Volovik effect, also known asmore » the Doppler shift effect, has been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.« less

Discretization of the total magnetic field by the nuclear spin bath in fluorine-doped ZnSe.

PubMed

Zhukov, E A; Kirstein, E; Kopteva, N E; Heisterkamp, F; Yugova, I A; Korenev, V L; Yakovlev, D R; Pawlis, A; Bayer, M; Greilich, A

2018-05-16

The coherent spin dynamics of fluorine donor-bound electrons in ZnSe induced by pulsed optical excitation is studied in a perpendicular applied magnetic field. The Larmor precession frequency serves as a measure for the total magnetic field exerted onto the electron spins and, surprisingly, does not increase linearly with the applied field, but shows a step-like behavior with pronounced plateaus, given by multiples of the laser repetition rate. This discretization occurs by a feedback mechanism in which the electron spins polarize the nuclear spins, which in turn generate a local Overhauser field adjusting the total magnetic field accordingly. Varying the optical excitation power, we can control the plateaus, in agreement with our theoretical model. From this model, we trace the observed discretization to the optically induced Stark field, which causes the dynamic nuclear polarization.

Experimental investigation of vector static magnetic field detection using an NV center with a single first-shell 13C nuclear spin in diamond

NASA Astrophysics Data System (ADS)

Jiang, Feng-Jian; Ye, Jian-Feng; Jiao, Zheng; Jiang, Jun; Ma, Kun; Yan, Xin-Hu; Lv, Hai-Jiang

2018-05-01

We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy (NV) color center with a nearest neighbor 13C nuclear spin in diamond to detect the strength and direction (including both polar and azimuth angles) of a static vector magnetic field by optical detection magnetic resonance (ODMR) technique. With the known hyperfine coupling tensor between an NV center and a nearest neighbor 13C nuclear spin, we show that the information of static vector magnetic field could be extracted by observing the pulsed continuous wave (CW) spectrum. Project supported by the National Natural Science Foundation of China (Grant Nos. 11305074, 11135002, and 11275083), the Key Program of the Education Department Outstanding Youth Foundation of Anhui Province, China (Grant No. gxyqZD2017080), and the Education Department Natural Science Foundation of Anhui Province, China (Grant No. KJHS2015B09).

Volovik effect and Fermi-liquid behavior in the s -wave superconductor CaPd 2 As 2 :   As 75 NMR-NQR measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Q. -P.; Wiecki, P.; Anand, V. K.

The electronic and magnetic properties of the collapsed-tetragonal CaPd 2As 2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T 1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/T 1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below T c and decreases exponentially at lower T, confirming a conventional s-wave SC. Additionally, the Volovik effect, also known asmore » the Doppler shift effect, has been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.« less

The search for axion-like dark matter using magnetic resonance

NASA Astrophysics Data System (ADS)

Sushkov, Alexander; Casper Collaboration

2016-05-01

The nature of dark matter is one of the most important open problems in modern physics, and it is necessary to develop techniques to search for a wide class of dark-matter candidates. Axions, originally introduced to resolve the strong CP problem in quantum chromodynamics (QCD), and axion-like particles (ALPs) are strongly motivated dark matter candidates. Nuclear spins interacting with axion-like background dark matter experience an energy shift, oscillating at the frequency equal to the axion Compton frequency. The Cosmic Axion Spin Precession Experiments (CASPEr) use precision magnetometry and nuclear magnetic resonance techniques to search for the effects of this interaction. The experimental signature is precession of the nuclear spins under the condition of magnetic resonance: when the bias magnetic field is tuned such that the nuclear spin sublevel splitting is equal to the axion Compton frequency. These experiments have the potential to detect axion-like dark matter in a wide mass range (10-12 eV to 10-6 eV, scanned by changing the bias magnetic field from approximately 1 gauss to 20 tesla) and with coupling strengths many orders of magnitude beyond the current astrophysical and laboratory limits, and all the way down to those corresponding to the QCD axion. Supported by the Heising-Simons Foundation.

High-Resolution Magnetic Analyzer MAVR for the Study of Exotic Weakly-Bound Nuclei

NASA Astrophysics Data System (ADS)

Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

2015-11-01

A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ~1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400-U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

1H-Nuclear Magnetic Resonance-Based Plasma Metabolic Profiling of Dairy Cows with Fatty Liver

PubMed Central

Xu, Chuang; Sun, Ling-wei; Xia, Cheng; Zhang, Hong-you; Zheng, Jia-san; Wang, Jun-song

2016-01-01

Fatty liver is a common metabolic disorder of dairy cows during the transition period. Historically, the diagnosis of fatty liver has involved liver biopsy, biochemical or histological examination of liver specimens, and ultrasonographic imaging of the liver. However, more convenient and noninvasive methods would be beneficial for the diagnosis of fatty liver in dairy cows. The plasma metabolic profiles of dairy cows with fatty liver and normal (control) cows were investigated to identify new biomarkers using 1H nuclear magnetic resonance. Compared with the control group, the primary differences in the fatty liver group included increases in β-hydroxybutyric acid, acetone, glycine, valine, trimethylamine-N-oxide, citrulline, and isobutyrate, and decreases in alanine, asparagine, glucose, γ-aminobutyric acid glycerol, and creatinine. This analysis revealed a global profile of endogenous metabolites, which may present potential biomarkers for the diagnosis of fatty liver in dairy cows. PMID:26732447

Application of Nuclear Magnetic Resonance and Hybrid Methods to Structure Determination of Complex Systems.

PubMed

Prischi, Filippo; Pastore, Annalisa

2016-01-01

The current main challenge of Structural Biology is to undertake the structure determination of increasingly complex systems in the attempt to better understand their biological function. As systems become more challenging, however, there is an increasing demand for the parallel use of more than one independent technique to allow pushing the frontiers of structure determination and, at the same time, obtaining independent structural validation. The combination of different Structural Biology methods has been named hybrid approaches. The aim of this review is to critically discuss the most recent examples and new developments that have allowed structure determination or experimentally-based modelling of various molecular complexes selecting them among those that combine the use of nuclear magnetic resonance and small angle scattering techniques. We provide a selective but focused account of some of the most exciting recent approaches and discuss their possible further developments.

[Hyperfine structure analysis in magnetic resonance spectroscopy: from astrophysical measurements towards endogenous biosensors in human tissue].

PubMed

Schröder, Leif

2007-01-01

The hyperfine interaction of two spins is a well studied effect in atomic systems. Magnetic resonance experiments demonstrate that the detectable dipole transitions are determined by the magnetic moments of the constituents and the external magnetic field. Transferring the corresponding quantum mechanics to molecular bound nuclear spins allows for precise prediction of NMR spectra obtained from metabolites in human tissue. This molecular hyperfine structure has been neglected so far in in vivo NMR spectroscopy but contains useful information, especially when studying molecular dynamics. This contribution represents a review of the concept of applying the Breit-Rabi formalism to coupled nuclear spins and discusses the immobilization of different metabolites in anisotropic tissue revealed by 1H NMR spectra of carnosine, phosphocreatine and taurine. Comparison of atomic and molecular spin systems allows for statements on the biological constraints for direct spin-spin interactions. Moreover, the relevance of hyperfine effects on the line shapes of multiplets of indirectly-coupled spin systems with more than two constituents can be predicted by analyzing quantum mechanical parameters. As an example, the superposition of eigenstates of the A MX system of adenosine 5'-triphosphate and its application for better quantification of 31P-NMR spectra will be discussed.

Properties of K,Rb-intercalated C{sub 60} encapsulated inside carbon nanotubes called peapods derived from nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahfouz, R.; Bouhrara, M.; Kim, Y.

2015-09-21

We present a detailed experimental study on how magnetic and electronic properties of Rb,K-intercalated C{sub 60} encapsulated inside carbon nanotubes called peapods can be derived from {sup 13}C nuclear magnetic resonance investigations. Ring currents do play a basic role in those systems; in particular, the inner cavities of nanotubes offer an ideal environment to investigate the magnetism at the nanoscale. We report the largest diamagnetic shifts down to −68.3 ppm ever observed in carbon allotropes, which is connected to the enhancement of the aromaticity of the nanotube envelope upon intercalation. The metallization of intercalated peapods is evidenced from the chemical shiftmore » anisotropy and spin-lattice relaxation (T{sub 1}) measurements. The observed relaxation curves signal a three-component model with two slow and one fast relaxing components. We assigned the fast component to the unpaired electrons charged C{sub 60} that show a phase transition near 100 K. The two slow components can be rationalized by the two types of charged C{sub 60} at two different positions with a linear regime following Korringa behavior, which is typical for metallic system and allow us to estimate the density of sate at Fermi level n(E{sub F})« less

Nuclear magnetic resonance metabolomics of iron deficiency in soybean leaves.

PubMed

Lima, Marta R M; Diaz, Sílvia O; Lamego, Inês; Grusak, Michael A; Vasconcelos, Marta W; Gil, Ana M

2014-06-06

Iron (Fe) deficiency is an important agricultural concern that leads to lower yields and crop quality. A better understanding of the condition at the metabolome level could contribute to the design of strategies to ameliorate Fe-deficiency problems. Fe-sufficient and Fe-deficient soybean leaf extracts and whole leaves were analyzed by liquid (1)H nuclear magnetic resonance (NMR) and high-resolution magic-angle spinning NMR spectroscopy, respectively. Overall, 30 compounds were measurable and identifiable (comprising amino and organic acids, fatty acids, carbohydrates, alcohols, polyphenols, and others), along with 22 additional spin systems (still unassigned). Thus, metabolite differences between treatment conditions could be evaluated for different compound families simultaneously. Statistically relevant metabolite changes upon Fe deficiency included higher levels of alanine, asparagine/aspartate, threonine, valine, GABA, acetate, choline, ethanolamine, hypoxanthine, trigonelline, and polyphenols and lower levels of citrate, malate, ethanol, methanol, chlorogenate, and 3-methyl-2-oxovalerate. The data indicate that the main metabolic impacts of Fe deficiency in soybean include enhanced tricarboxylic acid cycle activity, enhanced activation of oxidative stress protection mechanisms and enhanced amino acid accumulation. Metabolites showing accumulation differences in Fe-starved but visually asymptomatic leaves could serve as biomarkers for early detection of Fe-deficiency stress.

Fragment-Based Electronic Structure Approach for Computing Nuclear Magnetic Resonance Chemical Shifts in Molecular Crystals.

PubMed

Hartman, Joshua D; Beran, Gregory J O

2014-11-11

First-principles chemical shielding tensor predictions play a critical role in studying molecular crystal structures using nuclear magnetic resonance. Fragment-based electronic structure methods have dramatically improved the ability to model molecular crystal structures and energetics using high-level electronic structure methods. Here, a many-body expansion fragment approach is applied to the calculation of chemical shielding tensors in molecular crystals. First, the impact of truncating the many-body expansion at different orders and the role of electrostatic embedding are examined on a series of molecular clusters extracted from molecular crystals. Second, the ability of these techniques to assign three polymorphic forms of the drug sulfanilamide to the corresponding experimental (13)C spectra is assessed. This challenging example requires discriminating among spectra whose (13)C chemical shifts differ by only a few parts per million (ppm) across the different polymorphs. Fragment-based PBE0/6-311+G(2d,p) level chemical shielding predictions correctly assign these three polymorphs and reproduce the sulfanilamide experimental (13)C chemical shifts with 1 ppm accuracy. The results demonstrate that fragment approaches are competitive with the widely used gauge-invariant projector augmented wave (GIPAW) periodic density functional theory calculations.

Intramolecular Nuclear Flux Densities

NASA Astrophysics Data System (ADS)

Barth, I.; Daniel, C.; Gindensperger, E.; Manz, J.; PéRez-Torres, J. F.; Schild, A.; Stemmle, C.; Sulzer, D.; Yang, Y.

The topic of this survey article has seen a renaissance during the past couple of years. Here we present and extend the results for various phenomena which we have published from 2012-2014, with gratitude to our coauthors. The new phenomena include (a) the first reduced nuclear flux densities in vibrating diatomic molecules or ions which have been deduced from experimental pump-probe spectra; these "experimental" nuclear flux densities reveal several quantum effects including (b) the "quantum accordion", i.e., during the turn from bond stretch to bond compression, the diatomic system never stands still — instead, various parts of it with different bond lengths flow into opposite directions. (c) Wavepacket interferometry has been extended from nuclear densities to flux densities, again revealing new phenomena: For example, (d) a vibrating nuclear wave function with compact initial shape may split into two partial waves which run into opposite directions, thus causing interfering flux densities. (e) Tunneling in symmetric 1-dimensional double-well systems yields maximum values of the associated nuclear flux density just below the potential barrier; this is in marked contrast with negligible values of the nuclear density just below the barrier. (f) Nuclear flux densities of pseudorotating nuclei may induce huge magnetic fields. A common methodologic theme of all topics is the continuity equation which connects the time derivative of the nuclear density to the divergence of the flux density, subject to the proper boundary conditions. (g) Nearly identical nuclear densities with different boundary conditions may be related to entirely different flux densities, e.g., during tunneling in cyclic versus non-cyclic systems. The original continuity equation, density and flux density of all nuclei, or of all nuclear degrees of freedom, may be reduced to the corresponding quantities for just a single nucleus, or just a single degree of freedom.

Optical Pumping Spin Exchange 3He Gas Cells for Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.

2009-08-01

We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the 3He-N2 mixture. The cells could be refilled. The 3He reaches around 50% polarization in 5-15 hours.

(1)H-Nuclear magnetic resonance-based plasma metabolic profiling of dairy cows with clinical and subclinical ketosis.

PubMed

Sun, L W; Zhang, H Y; Wu, L; Shu, S; Xia, C; Xu, C; Zheng, J S

2014-03-01

The purpose of this study was to assess the metabolic profile of plasma samples from cows with clinical and subclinical ketosis. According to clinical signs and 3-hydroxybutyrate plasma levels, 81 multiparous Holstein cows were selected from a dairy farm 7 to 21 d after calving. The cows were divided into 3 groups: cows with clinical ketosis, cows with subclinical ketosis, and healthy control cows. (1)H-Nuclear magnetic resonance-based metabolomics was used to assess the plasma metabolic profiles of the 3 groups. The data were analyzed by principal component analysis, partial least squares discriminant analysis, and orthogonal partial least-squares discriminant analysis. The differences in metabolites among the 3 groups were assessed. The orthogonal partial least-squares discriminant analysis model differentiated the 3 groups of plasma samples. The model predicted clinical ketosis with a sensitivity of 100% and a specificity of 100%. In the case of subclinical ketosis, the model had a sensitivity of 97.0% and specificity of 95.7%. Twenty-five metabolites, including acetoacetate, acetone, lactate, glucose, choline, glutamic acid, and glutamine, were different among the 3 groups. Among the 25 metabolites, 4 were upregulated, 7 were downregulated, and 14 were both upregulated and downregulated. The results indicated that plasma (1)H-nuclear magnetic resonance-based metabolomics, coupled with pattern recognition analytical methods, not only has the sensitivity and specificity to distinguish cows with clinical and subclinical ketosis from healthy controls, but also has the potential to be developed into a clinically useful diagnostic tool that could contribute to a further understanding of the disease mechanisms. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The Role of Akt and its Substrates in Resistance of Breast Cancer to Trastuzumab

DTIC Science & Technology

2009-03-01

spectroscopy; Myr-Akt1 = constitutively active Akt1 mutant bearing the myristolation sequence from Src; NMR = nuclear magnetic resonance; PI3K...histological differences between ErbB/Ras and Wnt pathway transgenic mammary tumors. Am J Pathol 2002, 161:1087-1097. 24. Ishizawar RC, Miyake T

High-resolution NMR study of light and heavy crude oils: “structure-property” analysis

NASA Astrophysics Data System (ADS)

Rakhmatullin, I.; Efimov, S.; Varfolomeev, M.; Klochkov, V.

2018-05-01

Measurements of three light and one heavy crude oil samples were carried out by high-resolution nuclear magnetic resonance (NMR) spectroscopy methods. Quantitative fractions of aromatic molecules and functional groups constituting oil hydrocarbons were determined, and comparative analysis of the oil samples of different viscosity and origin was done.

SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC. Design of a multi-cusp ion source for proton therapy

NASA Astrophysics Data System (ADS)

Wu, Xiao-Bing; Huang, Tao; Ouyang, Hua-Fu; Zhang, Hua-Shun; Gong, Ke-Yun

2010-12-01

The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed. The three electrode extraction system is adopted and simulated. A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.

Comparison of the meat metabolite composition of Linwu and Pekin ducks using 600 MHz 1H nuclear magnetic resonance spectroscopy.

PubMed

Wang, Xiangrong; Fang, Chengkun; He, Jianhua; Dai, Qiuzhong; Fang, Rejun

2017-01-01

In an effort to further understand of the differences of meat flavor and texture between Linwu ducks and Pekin ducks at market age, we investigated the meat metabolite composition of the two breeds of ducks using 600 MHz 1 H nuclear magnetic resonance (NMR) spectroscopy. Comprehensive multivariate data analysis including principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal projection to latent structure-discriminant analysis (OPLS-DA) were applied to analyze the 1 H-NMR profiling data to identify the distinguishing metabolites of breast meat between two breeds of ducks. Compared with 42-d-old Pekin duck meat, breast from 72-d-old Linwu duck has higher concentration of anserine, carnosine, homocarnosine, and nicotinamide, but significantly lower concentration of succinate, creatine, and myo-inositol. These results contribute to a better understanding of the differences in meat metabolite composition between 72-d-old Linwu and 42-d-old Pekin ducks, which could be used to help assess the quality of duck meat as a food. © 2016 Poultry Science Association Inc.

The helium effect at grain boundaries in Fe-Cr alloys: A first-principles study

NASA Astrophysics Data System (ADS)

Zemła, M. R.; Wróbel, J. S.; Wejrzanowski, T.; Nguyen-Manh, D.; Kurzydłowski, K. J.

2017-02-01

Helium is produced in the structural materials in nuclear power plants by nuclear transmutation following neutron irradiation. Since the solubility of helium in all metals is extremely low, helium tends to be trapped at defects such as vacancies, dislocations and grain boundaries, which cause material embrittlement. Density functional theory (DFT) calculations were performed in order to investigate the helium effect at grain boundaries (GBs) in iron-chromium alloys. Both cohesive energy and magnetic properties at symmetric Σ3(1 1 1) and Σ5(2 1 0) tilt Fe GBs are studied in the presence of Cr and He atoms. It is found that the presence of Cr atoms increases cohesive energy, at different He concentrations, and strongly influences magnetic properties at the GBs. The effect of the segregation energy of helium atom as a function of the different positions of Cr atoms located inside/outside a GB has been considered. Results of the present first-principles study enable one to clarify the role of Cr in understanding the helium effect in Fe-Cr-based alloys.

Experimental aspect of solid-state nuclear magnetic resonance studies of biomaterials such as bones.

PubMed

Singh, Chandan; Rai, Ratan Kumar; Sinha, Neeraj

2013-01-01

Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is increasingly becoming a popular technique to probe micro-structural details of biomaterial such as bone with pico-meter resolution. Due to high-resolution structural details probed by SSNMR methods, handling of bone samples and experimental protocol are very crucial aspects of study. We present here first report of the effect of various experimental protocols and handling methods of bone samples on measured SSNMR parameters. Various popular SSNMR experiments were performed on intact cortical bone sample collected from fresh animal, immediately after removal from animal systems, and results were compared with bone samples preserved in different conditions. We find that the best experimental conditions for SSNMR parameters of bones correspond to preservation at -20 °C and in 70% ethanol solution. Various other SSNMR parameters were compared corresponding to different experimental conditions. Our study has helped in finding best experimental protocol for SSNMR studies of bone. This study will be of further help in the application of SSNMR studies on large bone disease related animal model systems for statistically significant results. © 2013 Elsevier Inc. All rights reserved.

Study of Magnetic Reconnection

DTIC Science & Technology

1988-11-01

and disruptions in the Tosca tokamak, Nuclear Fusion 19, 115-119, 1979. 9. Stenzel, R. L., W. Gekelman and N. Wild, Magnetic field line reconnection...Acknowledgments. The authors gratefully acknowledge the techni- plasma diffusion due to polycliromatic fluctuations, Nucl. Fussion , cal support and...sans collisions, in: Proceedings of the Conference on Plasma Physics and Controlled Nuclear Fusion, International Atomic Energy Agency, Vienna

C-13 nuclear magnetic resonance in organic geochemistry.

NASA Technical Reports Server (NTRS)

Balogh, B.; Wilson, D. M.; Burlingame, A. L.

1972-01-01

Study of C-13 nuclear magnetic resonance (NMR) spectra of polycyclic fused systems. The fingerprint qualities of the natural abundance in C-13 NMR spectra permitting unequivocal identification of these compounds is discussed. The principle of structural additivity of C-13 NMR information is exemplified on alpha and beta androstanes, alpha and beta cholestanes, ergostanes, sitostanes, and isodecanes.

Analysis on cocondensation of melamine and urea through carbon 13 enriched formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Treesearch

Bunichiro Tomita; Chung-Yun Hse

1995-01-01

The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins were synthesized using the labeling method of 13C enriched formaldehyde udner neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field shifts...

Analyses of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Treesearch

Tomita Bunchiro; Chung-Yun Hse

1995-01-01

The 13C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation...

Analyses of cocondensation of melamine and urea through carbon 13 enriched formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Treesearch

Tomita Bunchiro; Chung-Yun Hse

1995-01-01

The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins were synthesized using the labeling method with 13C enriched formaldehyde unde neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field...

Analysis of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Treesearch

Bunichiro Tomita; Chung-Yun Hse

1995-01-01

The 13C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation...

Qualitative analysis of the stability of the oxazine ring of various benzoxazine and pyridooxazine derivatives with proton nuclear magnetic resonance spectroscopy.

PubMed

Moloney, G P; Craik, D J; Iskander, M N

1992-07-01

A series of 3,4-dihydro-1,3-benzoxazine and 3,4-dihydro-1,3-pyridooxazine derivatives was synthesized, and the hydrolysis of the derivatives was studied with proton nuclear magnetic resonance spectroscopy. The oxazine derivatives underwent various degrees of hydrolysis when H2O was added to dimethyl sulfoxide solutions of the compounds. The rates and extents of decomposition of the oxazine ring systems depended on the electronic effects of substituents within the molecules. Examination of the proton nuclear magnetic resonance spectra that were generated during decomposition of the oxazines and trends in stability of the oxazine derivatives suggest the formation of an intermediate in the hydrolysis mechanism.

Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic-resonance spectrometry

USGS Publications Warehouse

Ha, Steven T.K.; Wilkins, Charles L.; Abidi, Sharon L.

1989-01-01

A mixture of closely related streptomyces fermentation products, antimycin A, Is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-μL NMR cell, Instead of a smaller 14-μL cell. Analysis of the antimycin A mixture, using the optimal analytical high performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.

HYPERFINE STRUCTURES AND NUCLEAR MOMENTS OF Lu$sup 176$m, Br$sup 80$, Br$sup 80$m, AND I$sup 132$ (thesis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, M.B.

1962-09-01

The method of atomic-beam radiofrequency spectroscopy was used to determine some nuclear and atomic properties of Lu/sup 176m/, Br/sup 80/, Br/sup 80m/, and I/sup 132/. Hyperfine structure me asurements were raade to determine the magnetic dipole interaction constants and the electric quadrupole interaction constants of all these isotopes. Also the nuclear spin and the electronic g/sub J/ factor were measured for Lu/sup 176m/, and the nuclear magnetic dipole moments and the electric quadrupole moments for the isotopes were calculated. All results are listed. 62 references. (auth)

DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

DOEpatents

Fan, N.Q.; Clarke, J.

1993-10-19

A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced. 7 figures.

DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

DOEpatents

Fan, Non Q.; Clarke, John

1993-01-01

A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced.

Many-body kinetics of dynamic nuclear polarization by the cross effect

NASA Astrophysics Data System (ADS)

Karabanov, A.; Wiśniewski, D.; Raimondi, F.; Lesanovsky, I.; Köckenberger, W.

2018-03-01

Dynamic nuclear polarization (DNP) is an out-of-equilibrium method for generating nonthermal spin polarization which provides large signal enhancements in modern diagnostic methods based on nuclear magnetic resonance. A particular instance is cross-effect DNP, which involves the interaction of two coupled electrons with the nuclear spin ensemble. Here we develop a theory for this important DNP mechanism and show that the nonequilibrium nuclear polarization buildup is effectively driven by three-body incoherent Markovian dissipative processes involving simultaneous state changes of two electrons and one nucleus. We identify different parameter regimes for effective polarization transfer and discuss under which conditions the polarization dynamics can be simulated by classical kinetic Monte Carlo methods. Our theoretical approach allows simulations of the polarization dynamics on an individual spin level for ensembles consisting of hundreds of nuclear spins. The insight obtained by these simulations can be used to find optimal experimental conditions for cross-effect DNP and to design tailored radical systems that provide optimal DNP efficiency.

Nuclear magnetic resonance in high magnetic field: Application to condensed matter physics

NASA Astrophysics Data System (ADS)

Berthier, Claude; Horvatić, Mladen; Julien, Marc-Henri; Mayaffre, Hadrien; Krämer, Steffen

2017-05-01

In this review, we describe the potentialities offered by the nuclear magnetic resonance (NMR) technique to explore at a microscopic level new quantum states of condensed matter induced by high magnetic fields. We focus on experiments realised in resistive (up to 34 T) or hybrid (up to 45 T) magnets, which open a large access to these quantum phase transitions. After an introduction on NMR observables, we consider several topics: quantum spin systems (spin-Peierls transition, spin ladders, spin nematic phases, magnetisation plateaus, and Bose-Einstein condensation of triplet excitations), the field-induced charge density wave (CDW) in high-Tc superconductors, and exotic superconductivity including the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state and the field-induced superconductivity due to the Jaccarino-Peter mechanism.

Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

DOEpatents

Fukushima, E.; Roeder, S.B.W.; Assink, R.A.; Gibson, A.A.V.

1984-01-01

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

DOEpatents

Fukushima, Eiichi; Roeder, Stephen B. W.; Assink, Roger A.; Gibson, Atholl A. V.

1986-01-01

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Nanometer-Scale Force Detected Nuclear Magnetic Resonance Imaging

DTIC Science & Technology

2013-01-01

different crystallographic orientation. Single crystal thin films should thus minimize the stray electric fields by reducing the number of grain ...from epitaxial Ag films, rather than polycrystalline Ag films. It is thought that grain boundaries in polycrystalline metal films give rise to stray...electric fields near the surface of the film. The electric fields are produced as a consequence of the work func- tion difference between grains of

Gallstones: A Worldwide Multifaceted Disease and Its Correlations with Gallbladder Carcinoma.

PubMed

Sharma, Raj Kumar; Sonkar, Kanchan; Sinha, Neeraj; Rebala, Pradeep; Albani, Ahmad Ebrah; Behari, Anu; Reddy, Duvvuri Nageshwar; Farooqui, Alvina; Kapoor, Vinay Kumar

2016-01-01

Gallstones (GS) associated diseases are among the most recurrent and frequent diseases delineated in India and United Arab Emirates. Several reports suggest that the association of GS with gallbladder cancer (GBC) is very high in Northern part of India; however, its occurrence in UAE and Southern part of India is notably low. Therefore, in the present study, we aimed to perform compositional analysis of GS in three different geographical areas by Solid State Nuclear Magnetic Resonance and Fourier Transformed Infrared spectroscopy. Natural abundance 13C cross polarization magic angle spinning Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy is employed for the analysis of human gallstone. Cholesterol, bilirubin and calcium carbonate were present in variant concentrations in GS obtained from three different geographical regions. Cholesterol was present predominantly in gallstones from North India. Bilirubin was found to be a main constituent in gallstones pertaining to South India. Whereas GS from UAE showed both cholesterol and bilirubin as their major constituents. Calcium carbonate was found in varying concentrations in gallstones acquired from different regions. Variation in environmental condition and dietary habits may contribute and affect the GS formation. Alterations in bile composition influence the GB and augment the crystallization of cholesterol. Analysis of different geographical regions GS could be an important stride to understand the etiology of GS diseases.

High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adelnia, Fatemeh; Lascialfari, Alessandro; Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia

2015-05-07

We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ringmore » and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.« less

Allan Cormack, Computerized Axial Tomography (CAT), and Magnetic Resonance

Science.gov Websites

Radiopharmaceuticals, DOE Technical Report, 1977 Emission Computed Tomography: A New Technique for the Quantitative Extending the Power of Nuclear Magnetic Resonance Techniques Magnetic Resonance Imaging Research Top Some

Childhood Ependymoma Treatment

MedlinePlus

... a neuro exam or a neurologic exam. MRI (magnetic resonance imaging) with gadolinium : A procedure that uses a magnet, ... the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI). Lumbar puncture : A procedure used to collect ...

Magnetic resonance imaging without field cycling at less than earth's magnetic field

NASA Astrophysics Data System (ADS)

Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

2015-03-01

A strong pre-polarization field, usually tenths of a milli-tesla in magnitude, is used to increase the signal-to-noise ratio in ordinary superconducting quantum interference device-based nuclear magnetic resonance/magnetic resonance imaging experiments. Here, we introduce an experimental approach using two techniques to remove the need for the pre-polarization field. A dynamic nuclear polarization (DNP) technique enables us to measure an enhanced resonance signal. In combination with a π / 2 pulse to avoid the Bloch-Siegert effect in a micro-tesla field, we obtained an enhanced magnetic resonance image by using DNP technique with a 34.5 μT static external magnetic field without field cycling. In this approach, the problems of eddy current and flux trapping in the superconducting pickup coil, both due to the strong pre-polarization field, become negligible.

The MaPLE device of Saha Institute of Nuclear Physics: construction and its plasma aspects.

PubMed

Pal, Rabindranath; Biswas, Subir; Basu, Subhasis; Chattopadhyay, Monobir; Basu, Debjyoti; Chaudhuri, Manis; Chowdhuri, Manis

2010-07-01

The Magnetized Plasma Linear Experimental (MaPLE) device is a low cost laboratory plasma device at Saha Institute of Nuclear Physics fabricated in-house with the primary aim of studying basic plasma physics phenomena such as plasma instabilities, wave propagation, and their nonlinear behavior in magnetized plasma regime in a controlled manner. The machine is specially designed to be a versatile laboratory device that can provide a number of magnetic and electric scenario to facilitate such studies. A total of 36 number of 20-turn magnet coils, designed such as to allow easy handling, is capable of producing a uniform, dc magnetic field of about 0.35 T inside the plasma chamber of diameter 0.30 m. Support structure of the coils is planned in an innovative way facilitating straightforward fabrication and easy positioning of the coils. Further special feature lies in the arrangement of the spacers between the coils that can be maneuvered rather easily to create different magnetic configurations. Various methods of plasma production can be suitably utilized according to the experimental needs at either end of the vacuum vessel. In the present paper, characteristics of a steady state plasma generated by electron cyclotron resonance method using 2.45 GHz microwave power are presented. Scans using simple probe drives revealed that a uniform and long plasma column having electron density approximately 3-5x10(10) cm(-3) and temperature approximately 7-10 eV, is formed in the center of the plasma chamber which is suitable for wave launching experiments.

Calculation of nuclear spin-spin coupling constants using frozen density embedding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Götz, Andreas W., E-mail: agoetz@sdsc.edu; Autschbach, Jochen; Visscher, Lucas, E-mail: visscher@chem.vu.nl

2014-03-14

We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects inmore » the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.« less

Accelerating two-dimensional nuclear magnetic resonance correlation spectroscopy via selective coherence transfer

NASA Astrophysics Data System (ADS)

Ye, Qimiao; Chen, Lin; Qiu, Wenqi; Lin, Liangjie; Sun, Huijun; Cai, Shuhui; Wei, Zhiliang; Chen, Zhong

2017-01-01

Nuclear magnetic resonance (NMR) spectroscopy serves as an important tool for both qualitative and quantitative analyses of various systems in chemistry, biology, and medicine. However, applications of one-dimensional 1H NMR are often restrained by the presence of severe overlap among different resonances. The advent of two-dimensional (2D) 1H NMR constitutes a promising alternative by extending the crowded resonances into a plane and thereby alleviating the spectral congestions. However, the enhanced ability in discriminating resonances is achieved at the cost of extended experimental duration due to necessity of various scans with progressive delays to construct the indirect dimension. Therefore, in this study, we propose a selective coherence transfer (SECOT) method to accelerate acquisitions of 2D correlation spectroscopy by converting chemical shifts into spatial positions within the effective sample length and then performing an echo planar spectroscopic imaging module to record the spatial and spectral information, which generates 2D correlation spectrum after 2D Fourier transformation. The feasibility and effectiveness of SECOT have been verified by a set of experiments under both homogeneous and inhomogeneous magnetic fields. Moreover, evaluations of SECOT for quantitative analyses are carried out on samples with a series of different concentrations. Based on these experimental results, the SECOT may open important perspectives for fast, accurate, and stable investigations of various chemical systems both qualitatively and quantitatively.

Sealed magic angle spinning nuclear magnetic resonance probe and process for spectroscopy of hazardous samples

DOEpatents

Cho, Herman M.; Washton, Nancy M.; Mueller, Karl T.; Sears, Jr., Jesse A.; Townsend, Mark R.; Ewing, James R.

2016-06-14

A magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) probe is described that includes double containment enclosures configured to seal and contain hazardous samples for analysis. The probe is of a modular design that ensures containment of hazardous samples during sample analysis while preserving spin speeds for superior NMR performance and convenience of operation.

Two-Dimensional Nuclear Magnetic Resonance Structure Determination Module for Introductory Biochemistry: Synthesis and Structural Characterization of Lyso-Glycerophospholipids

ERIC Educational Resources Information Center

Garrett, Teresa A.; Rose, Rebecca L.; Bell, Sidney M.

2013-01-01

In this laboratory module, introductory biochemistry students are exposed to two-dimensional [superscript 1]H-nuclear magnetic resonance of glycerophospholipids (GPLs). Working in groups of three, students enzymatically synthesized and purified a variety of 2-acyl lyso GPLs. The structure of the 2-acyl lyso GPL was verified using [superscript…

New Window into the Human Body

NASA Technical Reports Server (NTRS)

1985-01-01

Michael Vannier, MD, a former NASA engineer, recognized the similarity between NASA's computerized image processing technology and nuclear magnetic resonance. With technical assistance from Kennedy Space Center, he developed a computer program for Mallinckrodt Institute of Radiology enabling Nuclear Magnetic Resonance (NMR) to scan body tissue for earlier diagnoses. Dr. Vannier feels that "satellite imaging" has opened a new window into the human body.

Electrically-Generated Spin Polarization in Non-Magnetic Semiconductors

DTIC Science & Technology

2016-03-31

resolved Faraday rotation data due to electron spin polarization from previous pump pulses was characterized, and an analytic solution for this phase...electron spin polarization was shown to produce nuclear hyperpolarization through dynamic nuclear polarization. Time-resolved Faraday rotation...Distribution approved for public release. 3    Figure 3. Total magnetic field measured using time-resolved Faraday rotation with the electrically

Nondestructive evaluation using dipole model analysis with a scan type magnetic camera

NASA Astrophysics Data System (ADS)

Lee, Jinyi; Hwang, Jiseong

2005-12-01

Large structures such as nuclear power, thermal power, chemical and petroleum refining plants are drawing interest with regard to the economic aspect of extending component life in respect to the poor environment created by high pressure, high temperature, and fatigue, securing safety from corrosion and exceeding their designated life span. Therefore, technology that accurately calculates and predicts degradation and defects of aging materials is extremely important. Among different methods available, nondestructive testing using magnetic methods is effective in predicting and evaluating defects on the surface of or surrounding ferromagnetic structures. It is important to estimate the distribution of magnetic field intensity for applicable magnetic methods relating to industrial nondestructive evaluation. A magnetic camera provides distribution of a quantitative magnetic field with a homogeneous lift-off and spatial resolution. It is possible to interpret the distribution of magnetic field when the dipole model was introduced. This study proposed an algorithm for nondestructive evaluation using dipole model analysis with a scan type magnetic camera. The numerical and experimental considerations of the quantitative evaluation of several sizes and shapes of cracks using magnetic field images of the magnetic camera were examined.

29Si nuclear magnetic resonance study of URu 2Si 2 under pressure

DOE PAGES

Shirer, K. R.; Dioguardi, A. P.; Bush, B. T.; ...

2015-12-01

Here, we report 29Si nuclear magnetic resonance measurements of single crystals and aligned powders of URu 2Si 2 under pressure in the hidden order and paramagnetic phases. We find evidence for a reduction of the Knight shift with applied pressure, consistent with previous measurements of the static magnetic susceptibility. Previous measurements of the spin lattice relaxation time revealed a partial suppression of the density of states below 30 K. Here, we find that the temperature at which this suppression occurs is enhanced with applied pressure.

Pressure-resisting cell for high-pressure, high-resolution nuclear magnetic resonance measurements at very high magnetic fields

NASA Astrophysics Data System (ADS)

Yamada, H.; Nishikawa, K.; Honda, M.; Shimura, T.; Akasaka, K.; Tabayashi, K.

2001-02-01

A pressure-resisting cell system has been developed for high-pressure high-resolution nuclear magnetic resonance (NMR) measurements up to a maximum pressure of 600 MPa. This cell system is capable of performing high-pressure experiments with any standard spectrometer, including modern high field NMR machines. A full description of the high-pressure NMR assembly mounted on a 750 MHz spectrometer is presented along with a detailed explanation of the procedure for preparing the pressure-resisting quartz and glass cells.

Magnetic equivalence of terminal nuclei in the azide anion broken by nuclear spin relaxation

NASA Astrophysics Data System (ADS)

Bernatowicz, P.; Szymański, S.

NMR spectra of water solution of sodium azide selectively 15N labelled in the central position were studied using an iterative least-squares method. In agreement with predictions based on Bloch-Wangsness-Redfield nuclear spin relaxation theory, it is demonstrated that quadrupolar relaxation of the magnetically equivalent terminal 14N (spin-1) nuclei in the azide anion renders the J coupling between these nuclei an observable quantity. In isotropic fluids, this seems to be the first experimental evidence of relaxation-broken magnetic equivalence symmetry.

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging

ERIC Educational Resources Information Center

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Design Issues for Using Magnetic Materials in Radiation Environments at Elevated Temperature

NASA Technical Reports Server (NTRS)

Bowman, Cheryl L.

2013-01-01

One of the challenges of designing motors and alternators for use in nuclear powered space missions is accounting for the effects of radiation. Terrestrial reactor power plants use distance and shielding to minimize radiation damage but space missions must economize volume and mass. Past studies have shown that sufficiently high radiation levels can affect the magnetic response of hard and soft magnetic materials. Theoretical models explaining the radiation-induced degradation have been proposed but not verified. This paper reviews the literature and explains the cumulative effects of temperature, magnetic-load, and radiation-level on the magnetic properties of component materials. Magnetic property degradation is very specific to alloy choice and processing history, since magnetic properties are very much entwined with specific chemistry and microstructural features. However, there is basic theoretical as well as supportive experimental evidence that the negative impact to magnetic properties will be minimal if the bulk temperature of the material is less than fifty percent of the Curie temperature, the radiation flux is low, and the demagnetization field is small. Keywords: Magnets, Permanent Magnets, Power Converters, Nuclear Electric Power Generation, Radiation Tolerance.

Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

NASA Astrophysics Data System (ADS)

Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

2011-11-01

Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

NASA Astrophysics Data System (ADS)

Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

2012-03-01

Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

Nuclear reactor control apparatus

DOEpatents

Sridhar, Bettadapur N.

1983-11-01

Nuclear reactor core safety rod release apparatus comprises a control rod having a detent notch in the form of an annular peripheral recess at its upper end, a control rod support tube for raising and lowering the control rod under normal conditions, latches pivotally mounted on the control support tube with free ends thereof normally disposed in the recess in the control rod, and cam means for pivoting the latches out of the recess in the control rod when a scram condition occurs. One embodiment of the invention comprises an additional magnetically-operated latch for releasing the control rod under two different conditions, one involving seismic shock.

Preferential magnetic orientation in amorphous alloys determined by NFS and Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Procházka, Vít; Vrba, Vlastimil; Šretrová, Pavla; Smrčka, David; Miglierini, Marcel

2016-10-01

Amorphous and nanocrystalline alloys frequently exhibit anisotropic behavior, which is a consequence of magnetic moments preferential orientation. This study reports the results obtained from a set of nuclear forward scattering experiments and transmission Mössbauer spectroscopy experiments that we have run in order to determine the degree of crystallization and the preferential orientation of magnetic moments in the material. The nuclear forward scattering of synchrotron radiation and the transmission Mössbauer spectroscopy were performed on the nanocrystalline alloy of the composition Fe79Mo8Cu1B12. The experimental data were evaluated and magnetic texture was determined. Relevance of the results was confronted with transmission Mössbauer experiments.

Collisional considerations in axial-collection plasma mass filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ochs, I. E.; Gueroult, R.; Fisch, N. J.

The chemical inhomogeneity of nuclear waste makes chemical separations difficult, while the correlation between radioactivity and nuclear mass makes mass-based separation, and in particular plasma-based separation, an attractive alternative. Here, we examine a particular class of plasma mass filters, namely filters in which (a) species of different masses are collected along magnetic field lines at opposite ends of an open-field-line plasma device and (b) gyro-drift effects are important for the separation process. Using an idealized cylindrical model, we derive a set of dimensionless parameters which provide minimum necessary conditions for an effective mass filter function in the presence of ion-ionmore » and ion-neutral collisions. Through simulations of the constant-density profile, turbulence-free devices, we find that these parameters accurately describe the mass filter performance in more general magnetic geometries. We then use these parameters to study the design and upgrade of current experiments, as well as to derive general scalings for the throughput of production mass filters. Most importantly, we find that ion temperatures above 3 eV and magnetic fields above 104 G are critical to ensure a feasible mass filter function when operating at an ion density of 10 13 cm –3.« less

Collisional considerations in axial-collection plasma mass filters

DOE PAGES

Ochs, I. E.; Gueroult, R.; Fisch, N. J.; ...

2017-04-01

The chemical inhomogeneity of nuclear waste makes chemical separations difficult, while the correlation between radioactivity and nuclear mass makes mass-based separation, and in particular plasma-based separation, an attractive alternative. Here, we examine a particular class of plasma mass filters, namely filters in which (a) species of different masses are collected along magnetic field lines at opposite ends of an open-field-line plasma device and (b) gyro-drift effects are important for the separation process. Using an idealized cylindrical model, we derive a set of dimensionless parameters which provide minimum necessary conditions for an effective mass filter function in the presence of ion-ionmore » and ion-neutral collisions. Through simulations of the constant-density profile, turbulence-free devices, we find that these parameters accurately describe the mass filter performance in more general magnetic geometries. We then use these parameters to study the design and upgrade of current experiments, as well as to derive general scalings for the throughput of production mass filters. Most importantly, we find that ion temperatures above 3 eV and magnetic fields above 104 G are critical to ensure a feasible mass filter function when operating at an ion density of 10 13 cm –3.« less

Heisenberg necklace model in a magnetic field

DOE PAGES

Tsvelik, A. M.; Zaliznyak, I. A.

2016-08-26

Here, we study the low-energy sector of the Heisenberg necklace model. Using the field-theory methods, we estimate how the coupling of the electronic spins with the paramagnetic Kondo spins affects the overall spin dynamics and evaluate its dependence on a magnetic field. We are motivated by the experimental realizations of the spin-1/2 Heisenberg chains in SrCuO 2 and Sr 2CuO 3 cuprates, which remain one-dimensional Luttinger liquids down to temperatures much lower than the in-chain exchange coupling J. We also consider the perturbation of the energy spectrum caused by the interaction γ with nuclear spins (I=3/2) present on the samemore » sites. We find that the resulting necklace model has a characteristic energy scale, Λ~J 1/3(γI) 2/3, at which the coupling between (nuclear) spins of the necklace and the spins of the Heisenberg chain becomes strong. Furthermore, this energy scale is insensitive to a magnetic field B. For μBB>Λ we find two gapless bosonic modes that have different velocities, whose ratio at strong fields approaches a universal number, 2√+1.« less

Quantum versus classical hyperfine-induced dynamics in a quantum dota)

NASA Astrophysics Data System (ADS)

Coish, W. A.; Loss, Daniel; Yuzbashyan, E. A.; Altshuler, B. L.

2007-04-01

In this article we analyze spin dynamics for electrons confined to semiconductor quantum dots due to the contact hyperfine interaction. We compare mean-field (classical) evolution of an electron spin in the presence of a nuclear field with the exact quantum evolution for the special case of uniform hyperfine coupling constants. We find that (in this special case) the zero-magnetic-field dynamics due to the mean-field approximation and quantum evolution are similar. However, in a finite magnetic field, the quantum and classical solutions agree only up to a certain time scale t <τc, after which they differ markedly.

Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baba, Shintaro; Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo

2016-02-01

Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electricmore » field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.« less

Magnetic Correlations In A Magnetite Nanoparticle Assembly Investigated Using Polarized SANS

NASA Astrophysics Data System (ADS)

Krycka, Kathryn; Hogg, Charles; Ijiri, Yumi; Booth, Ryan; Borchers, Julie; Chen, Wangchun; Laver, Mark; Gentile, Thomas; Maranville, Brian; Breslauer, Benjamin; Majetich, Sara

2008-03-01

Using small angle neutron scattering (SANS) with polarization analysis, we have studied ferromagnetic magnetite monodisperse nanospheres in order to determine the field (0 and 1.3 Tesla) and temperature (50, 100, and 200 K) dependence of the magnetic interparticle correlations. These particles were 7 nm in diameter with an average edge-to-edge separation of 2.5 nm. Preparation techniques are described elsewhere [1]. An FeSi supermirror polarized the incident neutrons, and a polarized 3He cell was used as a spin analyzer. While a typical magnetic SANS experiment observes the convolution of the nuclear and magnetic terms, we have implemented and further developed an algorithm to separate the four spin dependent cross sections. This provides an unambiguous separation and measurement of magnetic and nuclear contributions. At low temperatures, magnetic correlation lengths have been found to be significantly larger than at high temperatures.[1] J. Am. Chem. Soc. 2002, 124, 8204-8205.

Analytic treatment of nuclear spin-lattice relaxation for diffusion in a cone model

NASA Astrophysics Data System (ADS)

Sitnitsky, A. E.

2011-12-01

We consider nuclear spin-lattice relaxation rate resulted from a diffusion equation for rotational wobbling in a cone. We show that the widespread point of view that there are no analytical expressions for correlation functions for wobbling in a cone model is invalid and prove that nuclear spin-lattice relaxation in this model is exactly tractable and amenable to full analytical description. The mechanism of relaxation is assumed to be due to dipole-dipole interaction of nuclear spins and is treated within the framework of the standard Bloemberger, Purcell, Pound-Solomon scheme. We consider the general case of arbitrary orientation of the cone axis relative the magnetic field. The BPP-Solomon scheme is shown to remain valid for systems with the distribution of the cone axes depending only on the tilt relative the magnetic field but otherwise being isotropic. We consider the case of random isotropic orientation of cone axes relative the magnetic field taking place in powders. Also we consider the cases of their predominant orientation along or opposite the magnetic field and that of their predominant orientation transverse to the magnetic field which may be relevant for, e.g., liquid crystals. Besides we treat in details the model case of the cone axis directed along the magnetic field. The latter provides direct comparison of the limiting case of our formulas with the textbook formulas for free isotropic rotational diffusion. The dependence of the spin-lattice relaxation rate on the cone half-width yields results similar to those predicted by the model-free approach.

15N-CPMAS nuclear magnetic resonace spectroscopy and biological stability of soil organic nitrogen in whole soil and particle-size fractions

Treesearch

R.J. DiCosty; D.P. Weliky; S.J. Anderson; E.A. Paul

2003-01-01

Soil organic nitrogen was quantified by solid-state 15N cross-polarization nuclear magnetic resonance spectroscopy (NMR) during a 14-month laboratory incubation of a sandy loam soil amended with 15N-clover. In whole soil and particle-size fractions, the clover-derived N was always 85-90% amide, 5 10% guanidinium N of...

Electronic Measurement of Rock Stress

DTIC Science & Technology

atomic resonances that are pressure-sensitive. Nuclear quadrupole resonance ( NQR ) appeared clearly applicable, since no magnetic aligning field is needed...there are several common NQR -active nuclear species in major rock-forming minerals, and rf magnetic fields between 0.3 and 3 megahertz (the resonant...comprehensive literature search has been completed on NQR in minerals, which shows that aluminum-27 and a few other elements in feldspars are promising

Performance of new 400-MHz HTS power-driven magnet NMR technology on typical pharmaceutical API, cinacalcet HCl.

PubMed

Silva Elipe, Maria Victoria; Donovan, Neil; Krull, Robert; Pooke, Donald; Colson, Kimberly L

2018-04-17

After years towards higher field strength magnets, nuclear magnetic resonance (NMR) technology in commercial instruments in the past decade has expanded at low and high magnetic fields to take advantage of new opportunities. At lower field strengths, permanent magnets are well established, whereas for midrange and high field, developments utilize superconducting magnets cooled with cryogenic liquids. Recently, the desire to locate NMR spectrometers in nontypical NMR laboratories has created interest in the development of cryogen-free magnets. These magnets require no cryogenic maintenance, eliminating routine filling and large cryogen dewars in the facility. Risks of spontaneous quenches and safety concerns when working with cryogenic liquids are eliminated. The highest field commercially available cryogen-free NMR magnet previously reported was at 4.7 T in 2013. Here we tested a prototype cryogen-free 9.4-T power-driven high-temperature-superconducting (HTS) magnet mated to commercial NMR spectrometer electronics. We chose cinacalcet HCl, a typical active pharmaceutical ingredient, to evaluate its performance towards structure elucidation. Satisfactory standard 1D and 2D homonuclear and heteronuclear NMR results were obtained and compared with those from a standard 9.4-T cryogenically cooled superconducting NMR instrument. The results were similar between both systems with minor differences. Further comparison with different shims and probes in the HTS magnet system confirmed that the magnet homogeneity profile could be matched with commercially available NMR equipment for optimal results. We conclude that HTS magnet technology works well providing results comparable with those of standard instruments, leading us to investigate additional applications for this magnet technology outside a traditional NMR facility. Copyright © 2018 John Wiley & Sons, Ltd.

Computer programs of information processing of nuclear physical methods as a demonstration material in studying nuclear physics and numerical methods

NASA Astrophysics Data System (ADS)

Bateev, A. B.; Filippov, V. P.

2017-01-01

The principle possibility of using computer program Univem MS for Mössbauer spectra fitting as a demonstration material at studying such disciplines as atomic and nuclear physics and numerical methods by students is shown in the article. This program is associated with nuclear-physical parameters such as isomer (or chemical) shift of nuclear energy level, interaction of nuclear quadrupole moment with electric field and of magnetic moment with surrounded magnetic field. The basic processing algorithm in such programs is the Least Square Method. The deviation of values of experimental points on spectra from the value of theoretical dependence is defined on concrete examples. This value is characterized in numerical methods as mean square deviation. The shape of theoretical lines in the program is defined by Gaussian and Lorentzian distributions. The visualization of the studied material on atomic and nuclear physics can be improved by similar programs of the Mössbauer spectroscopy, X-ray Fluorescence Analyzer or X-ray diffraction analysis.

The Bloch equation with terms induced by an electric field

NASA Astrophysics Data System (ADS)

Garbacz, Piotr

2018-01-01

The Bloch equation of the nuclear magnetization of spin-1/2 nuclei in molecules, which have permanent electric dipole moments μe that are placed simultaneously in a magnetic field B and an electric field E, is derived. It is shown that if the principal components of the nuclear magnetic shielding tensor σ and the dipole moment μe are known, then the measurement of the transverse component to the magnetic field B of the nuclear magnetization, which is induced by the application of the electric field oscillating at the half of the spin precession frequency, allows determining the orientation of the dipole moment μe with respect to the principal axis system of the symmetric part of the tensor σ. Four-component relativistic density functional theory computations, which have been performed for several molecules containing heavy nuclei, i.e., 207Pb, 205Tl, 199Hg, 195Pt, and 125Te, indicate that coefficients of the relaxation matrix perturbed by the electric field E are in favorable cases of the order of 1000 pm2 V-2 T-2. Therefore, the spin dynamics is perturbed at experimentally observable levels for the strengths of electric and magnetic fields E = 5 kV/mm and B = 10 T, respectively.

High resolution NMR study of T{sub 1} magnetic relaxation dispersion. IV. Proton relaxation in amino acids and Met-enkephalin pentapeptide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru

2014-10-21

Nuclear Magnetic Relaxation Dispersion (NMRD) of protons was studied in the pentapeptide Met-enkephalin and the amino acids, which constitute it. Experiments were run by using high-resolution Nuclear Magnetic Resonance (NMR) in combination with fast field-cycling, thus enabling measuring NMRD curves for all individual protons. As in earlier works, Papers I–III, pronounced effects of intramolecular scalar spin-spin interactions, J-couplings, on spin relaxation were found. Notably, at low fields J-couplings tend to equalize the apparent relaxation rates within networks of coupled protons. In Met-enkephalin, in contrast to the free amino acids, there is a sharp increase in the proton T{sub 1}-relaxation timesmore » at high fields due to the changes in the regime of molecular motion. The experimental data are in good agreement with theory. From modelling the relaxation experiments we were able to determine motional correlation times of different residues in Met-enkephalin with atomic resolution. This allows us to draw conclusions about preferential conformation of the pentapeptide in solution, which is also in agreement with data from two-dimensional NMR experiments (rotating frame Overhauser effect spectroscopy). Altogether, our study demonstrates that high-resolution NMR studies of magnetic field-dependent relaxation allow one to probe molecular mobility in biomolecules with atomic resolution.« less

Multinuclear Detection of Nuclear Spin Optical Rotation at Low Field.

PubMed

Zhu, Yue; Gao, Yuheng; Rodocker, Shane; Savukov, Igor; Hilty, Christian

2018-06-06

We describe the multinuclear detection of nuclear spin optical rotation (NSOR), an effect dependent on the hyperfine interaction between nuclear spins and electrons. Signals of 1 H and 19 F are discriminated by frequency in a single spectrum acquired at sub-millitesla field. The simultaneously acquired optical signal along with the nuclear magnetic resonance signal allows the calculation of the relative magnitude of the NSOR constants corresponding to different nuclei within the sample molecules. This is illustrated by a larger NSOR signal measured at the 19 F frequency despite a smaller corresponding spin concentration. Second, it is shown that heteronuclear J-coupling is observable in the NSOR signal, which can be used to retrieve chemical information. Multinuclear frequency and J resolution can localize optical signals in the molecule. Properties of electronic states at multiple sites in a molecule may therefore ultimately be determined by frequency-resolved NSOR spectroscopy at low field.

Quantum Magnetism Applied to the Iron-Pnictides and Rare Earth Pyrochlores

NASA Astrophysics Data System (ADS)

Applegate, Ryan

This dissertation presents computational studies of two families of magnetic materials of significant current interest. The iron pnictides are new high temperature superconductors with interesting parent compound antiferromagnetism. The rare earth pyrochlore material Yb2Ti2O7 is a candidate quantum spin ice. The magnetic and structural phases of individual iron pnictides have both many common features and material specific differences. In an attempt to unify these behaviors as instances of a larger theoretical picture, we use Monte Carlo simulations of a two-dimensional Hamiltonian with coupled Heisenberg-spin and Ising-orbital degrees of freedom. We introduce spin-space and single-ion anisotropies and study the finite temperature transitions in our model. We develop a phase diagram and propose that the interplay of spin and orbital physics in the presence of anisotropy could explain how material details affect the transitions of the pnictide materials. Nuclear magnetic resonance (NMR) can study magnetic materials via the hyperfine interaction and the coupling between the nuclear moment and the field produced by the samples local moment environment. Recent measurements suggest that Zn doped BaFe2As2 may have quantum fluctuations about the striped phase that produce a distribution of fields at As nuclear sites. The non-magnetic ion Zn replaces Fe and can be treated as an impurity which can be studied by a zero-temperature Ising Series expansion method. We propose a Heisenberg-like J1a-J 1b-J2 model which has small ferromagnetic exchanges along the b axis and strong antiferromagnetic exchanges along the a axis. In our impurity model we find that the magnetic moments are everywhere reduced by quantum fluctuations, except on the nearest neighbor site in the AFM direction. We suggest that the presented impurity model may provide an explanation for the experimental measurements. Based on a recently proposed quantum spin ice model, we use numerical linked cluster (NLC) expansions to study thermodynamic properties of Yb 2Ti2O7. We show that high field fitting of inelastic neutron scattering experiments is an excellent method in determining the exchange constants of these materials. We calculate the heat capacity, entropy and magnetization as a function of temperature and field along a few high symmetry field directions. We compare our theoretical predictions to experiments and find remarkable agreement. These studies highlight the importance of localized model Hamiltonians in understanding magnetic properties of complex materials.

Nuclear magnetic biosignatures in the carbonaceous matter of ancient cherts: comparison with carbonaceous meteorites.

PubMed

Gourier, Didier; Delpoux, Olivier; Binet, Laurent; Vezin, Hervé

2013-10-01

The search for organic biosignatures is motivated by the hope of understanding the conditions of emergence of life on Earth and the perspective of finding traces of extinct life in martian sediments. Paramagnetic radicals, which exist naturally in amorphous carbonaceous matter fossilized in Precambrian cherts, were used as local structural probes and studied by electron paramagnetic resonance (EPR) spectroscopy. The nuclear magnetic resonance transitions of elements inside and around these radicals were detected by monitoring the nuclear modulations of electron spin echo in pulsed EPR. We found that the carbonaceous matter of fossilized microorganisms with age up to 3.5 billion years gives specific nuclear magnetic signatures of hydrogen (¹H), carbon (¹³C), and phosphorus (³¹P) nuclei. We observed that these potential biosignatures of extinct life are found neither in the carbonaceous matter of carbonaceous meteorites (4.56 billion years), the most ancient objects of the Solar System, nor in any carbonaceous matter resulting from carbonization of organic and bioorganic precursors. These results indicate that these nuclear signatures are sensitive to thermal episodes and can be used for Archean cherts with metamorphism not higher than the greenschist facies.

Errors in the Calculation of 27Al Nuclear Magnetic Resonance Chemical Shifts

PubMed Central

Wang, Xianlong; Wang, Chengfei; Zhao, Hui

2012-01-01

Computational chemistry is an important tool for signal assignment of 27Al nuclear magnetic resonance spectra in order to elucidate the species of aluminum(III) in aqueous solutions. The accuracy of the popular theoretical models for computing the 27Al chemical shifts was evaluated by comparing the calculated and experimental chemical shifts in more than one hundred aluminum(III) complexes. In order to differentiate the error due to the chemical shielding tensor calculation from that due to the inadequacy of the molecular geometry prediction, single-crystal X-ray diffraction determined structures were used to build the isolated molecule models for calculating the chemical shifts. The results were compared with those obtained using the calculated geometries at the B3LYP/6-31G(d) level. The isotropic chemical shielding constants computed at different levels have strong linear correlations even though the absolute values differ in tens of ppm. The root-mean-square difference between the experimental chemical shifts and the calculated values is approximately 5 ppm for the calculations based on the X-ray structures, but more than 10 ppm for the calculations based on the computed geometries. The result indicates that the popular theoretical models are adequate in calculating the chemical shifts while an accurate molecular geometry is more critical. PMID:23203134

Self-contained high-pressure cell, apparatus, and procedure for the preparation of encapsulated proteins dissolved in low viscosity fluids for nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Peterson, Ronald W.; Wand, A. Joshua

2005-09-01

The design of a sample cell for high-performance nuclear magnetic resonance (NMR) at elevated pressure is described. The cell has been optimized for the study of encapsulated proteins dissolved in low viscosity fluids but is suitable for more general nuclear magnetic resonance (NMR) spectroscopy of biomolecules at elevated pressure. The NMR cell is comprised of an alumina-toughened zirconia tube mounted on a self-sealing nonmagnetic metallic valve. The cell has several advantages, including relatively low cost, excellent NMR performance, high-pressure tolerance, chemical inertness, and a relatively large active volume. Also described is a low volume sample preparation device that allows for the preparation of samples under high hydrostatic pressure and their subsequent transfer to the NMR cell.

Genome-wide analysis of nuclear magnetic resonance metabolites revealed parent-of-origin effect on triglycerides in medium very low-density lipoprotein in PTPRD gene.

PubMed

Pervjakova, N; Kukushkina, V; Haller, T; Kasela, S; Joensuu, A; Kristiansson, K; Annilo, T; Perola, M; Salomaa, V; Jousilahti, P; Metspalu, A; Mägi, R

2018-05-01

The aim of the study was to explore the parent-of-origin effects (POEs) on a range of human nuclear magnetic resonance metabolites. We search for POEs in 14,815 unrelated individuals from Estonian and Finnish cohorts using POE method for the genotype data imputed with 1000 G reference panel and 82 nuclear magnetic resonance metabolites. Meta-analysis revealed the evidence of POE for the variant rs1412727 in PTPRD gene for the metabolite: triglycerides in medium very low-density lipoprotein. No POEs were detected for genetic variants that were previously known to have main effect on circulating metabolites. We demonstrated possibility to detect POEs for human metabolites, but the POEs are weak, and therefore it is hard to detect those using currently available sample sizes.

Surface diffusion of CO on silica-supported Ru particles: 13C nuclear magnetic resonance studies

NASA Astrophysics Data System (ADS)

Duncan, T. M.; Thayer, A. M.; Root, T. W.

1990-02-01

Portions of CO adsorbed on Ru particles, selected by the orientation of the C-O bond relative to an external magnetic field, are labeled by inversion of the 13C nuclear magnetic dipole. Changes in the orientation of the CO bond of these labeled molecules are then observed with 13C NMR spectroscopy. The temperature dependence and rate of reorientation are consistent with surface diffusion on Ru particles with small numbers of flat faces. The insensitivity to CO pressure in the range 0.5-100 Torr discounts stimulated desorption by gas-phase CO.

Entanglement and Metrology with Singlet-Triplet Qubits

NASA Astrophysics Data System (ADS)

Shulman, Michael Dean

Electron spins confined in semiconductor quantum dots are emerging as a promising system to study quantum information science and to perform sensitive metrology. Their weak interaction with the environment leads to long coherence times and robust storage for quantum information, and the intrinsic tunability of semiconductors allows for controllable operations, initialization, and readout of their quantum state. These spin qubits are also promising candidates for the building block for a scalable quantum information processor due to their prospects for scalability and miniaturization. However, several obstacles limit the performance of quantum information experiments in these systems. For example, the weak coupling to the environment makes inter-qubit operations challenging, and a fluctuating nuclear magnetic field limits the performance of single-qubit operations. The focus of this thesis will be several experiments which address some of the outstanding problems in semiconductor spin qubits, in particular, singlet-triplet (S-T0) qubits. We use these qubits to probe both the electric field and magnetic field noise that limit the performance of these qubits. The magnetic noise bath is probed with high bandwidth and precision using novel techniques borrowed from the field of Hamiltonian learning, which are effective due to the rapid control and readout available in S-T 0 qubits. These findings allow us to effectively undo the undesired effects of the fluctuating nuclear magnetic field by tracking them in real-time, and we demonstrate a 30-fold improvement in the coherence time T2*. We probe the voltage noise environment of the qubit using coherent qubit oscillations, which is partially enabled by control of the nuclear magnetic field. We find that the voltage noise bath is frequency-dependent, even at frequencies as high as 1MHz, and it shows surprising and, as of yet, unexplained temperature dependence. We leverage this knowledge of the voltage noise environment, the nuclear magnetic field control, as well as new techniques for calibrated measurement of the density matrix in a singlet-triplet qubit to entangle two adjacent single-triplet qubits. We fully characterize the generated entangled states and prove that they are, indeed, entangled. This work opens new opportunities to use qubits as sensors for improved metrological capabilities, as well as for improved quantum information processing. The singlet-triplet qubit is unique in that it can be used to probe two fundamentally different noise baths, which are important for a large variety of solid state qubits. More specifically, this work establishes the singlet-triplet qubit as a viable candidate for the building block of a scalable quantum information processor.

Development of Selective Excitation Methods in Nuclear Magnetic Resonance: Investigation of Hemoglobin Oxygenation in Erythrocytes Using Proton and Phosphorus -31 Nuclear Magnetic Resonance

NASA Astrophysics Data System (ADS)

Fetler, Bayard Keith

1993-01-01

Nuclear magnetic resonance (NMR) offers a potential method for making measurements of the percent oxygenation of hemoglobin (Hb) in living tissue non-invasively. As a demonstration of the feasibility of such measurements, we measured the percent oxygenation of Hb in red blood cells (erythrocytes) using resonances in the proton-NMR (^1H-NMR) spectrum which are characteristic of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb), and are due to the unique magnetic properties of these molecules. To perform these measurements, we developed a new NMR method of selectively exciting signals in a region of interest with uniform phase and amplitude, while suppressing the signal of the water resonance. With this method, we are able to make exact calculations distinguishing between uniform phase excitation produced at large flip-angles using the non-linear properties of the Bloch equations, and uniform phase excitation produced at small flip-angles using asymmetric pulse excitation functions. We measured the percent oxygenation of three characteristic ^1H-NMR resonances of Hb: two from deoxy-Hb, originating from the N_delta H protons of histidine residue F8, which occur at different frequencies for the alpha and beta chains of Hb; and one from oxy-Hb, originating from the gamma_2 -CH_3 protons of valine residue E11. We performed experiments both on fresh erythrocytes and on erythrocytes depleted of 2,3-diphosphoglycerate (2,3-DPG), and found that oxygen is more tightly bound to Hb in the former case. In both fresh and 2,3-DPG-depleted samples, we found that: (i) from the deoxy-Hb marker resonances, there is a small but significant difference in the oxygen saturation between the alpha and beta chains; (ii) the decrease in the areas of the deoxy-Hb marker resonances correlates well with the increase in the percent oxygenation of Hb as measured optically; (iii) the area of the oxy-Hb marker resonance may be up to ~15% less than the optically measured Hb saturation. We are thus able to demonstrate the feasibility and validity of using this method to measure the oxygen saturation of Hb using ^1H-NMR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, W.; Korea Basic Science Institute; Stepanyan, S. S.

We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping ismore » used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the {sup 3}He-N{sub 2} mixture. The cells could be refilled. The {sup 3}He reaches around 50% polarization in 5-15 hours.« less

Elasticity and magnetocaloric effect in MnFe 4Si 3

DOE PAGES

Herlitschke, Marcus; Klobes, B.; Sergueev, I.; ...

2016-03-16

The room temperature magnetocaloric material MnFe 4Si 3 was investigated with nuclear inelastic scattering (NIS) and resonant ultrasound spectroscopy (RUS) at different temperatures and applied magnetic fields in order to assess the infuence of the magnetic transition and the magnetocaloric effect on the lattice dynamics. The NIS data give access to phonons with energies above 3 meV, whereas RUS probes the elasticity of the material in the MHz frequency range and thus low energy, ~5 neV, phonon modes. A significant infuence of the magnetic transition on the lattice dynamics is observed only in the low energy region. Here, MnFe 4Simore » 3 and other compounds in the Mn 5-xFe xSi 3 series were also investigated with vibrating sample magnetometry, resistivity measurements and Moessbauer spectroscopy in order to study the magnetic transitions and to complement the obtained results on the lattice dynamics.« less

Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

PubMed

Danieli, E; Perlo, J; Blümich, B; Casanova, F

2013-05-03

Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

A facile synthesis and carbon-13 nuclear magnetic resonance spectral properties of 7-ketocholesteryl benzoate.

PubMed

Parish, E J; Wei, T Y; Livant, P

1987-10-01

This paper presents a modified method of the selective allylic oxidation of cholesteryl benzoate. Pyridinium chlorochromate, in refluxing benzene, has been found to be an effective and convenient reagent for the efficient oxidation of cholesteryl benzoate to 7-ketocholesteryl benzoate in high yield. Also included herein are the carbon-13 nuclear magnetic resonance spectral properties of 7-ketocholesteryl benzoate and cholesteryl benzoate.

The Use and Evaluation of Scaffolding, Student Centered-Learning, Behaviorism, and Constructivism to Teach Nuclear Magnetic Resonance and IR Spectroscopy in a Two-Semester Organic Chemistry Course

ERIC Educational Resources Information Center

Livengood, Kimberly; Lewallen, Denver W.; Leatherman, Jennifer; Maxwell, Janet L.

2012-01-01

Since 2002, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry have been introduced at the beginning of the first-semester organic chemistry lab course at this university. Starting in 2008, each individual student was given 20 unique homework problems that consisted of multiple-choice [superscript 1]H NMR and IR problems…

Nuclear magnetic resonance of molecular hydrogen trapped in single-walled carbon nanotube bundles.

PubMed

Shiraishi, Masashi; Ata, Masafumi

2002-10-01

Molecular dynamics of hydrogen trapped in single-walled carbon nanotube bundles was analyzed by nuclear magnetic resonance. The chemical shift of hydrogen was about 5.1 ppm at 293 K, which is similar to that of water. The relaxation time, T1, was about 0.1-0.2 s. Values in this work are comparable to those for hydrogen loaded in silica and a-Si.

Interaction between adrenaline and dibenzo-18-crown-6: Electrochemical, nuclear magnetic resonance, and theoretical study

NASA Astrophysics Data System (ADS)

Yu, Zhang-Yu; Liu, Tao; Wang, Xue-Liang

2014-12-01

The interaction between adrenaline (Ad) and dibenzo-18-crown-6 (DB18C6) was studied by cyclic voltammetry, nuclear magnetic resonance spectroscopy, and the theoretical calculations, respectively. The results show that DB18C6 will affect the electron transfer properties of Ad. DB18C6 can form stable supramolecular complexes with Ad through ion-dipole and hydrogen bond interactions.

DIFFERENTIATION OF AURANTII FRUCTUS IMMATURUS AND FRUCTUS PONICIRI TRIFOLIATAE IMMATURUS BY FLOW-INJECTION WITH ULTRAVIOLET SPECTROSCOPIC DETECTION AND PROTON NUCLEAR MAGNETIC RESONANCE USING PARTIAL LEAST-SQUARES DISCRIMINANT ANALYSIS.

PubMed

Zhang, Mengliang; Zhao, Yang; Harrington, Peter de B; Chen, Pei

2016-03-01

Two simple fingerprinting methods, flow-injection coupled to ultraviolet spectroscopy and proton nuclear magnetic resonance, were used for discriminating between Aurantii fructus immaturus and Fructus poniciri trifoliatae immaturus . Both methods were combined with partial least-squares discriminant analysis. In the flow-injection method, four data representations were evaluated: total ultraviolet absorbance chromatograms, averaged ultraviolet spectra, absorbance at 193, 205, 225, and 283 nm, and absorbance at 225 and 283 nm. Prediction rates of 100% were achieved for all data representations by partial least-squares discriminant analysis using leave-one-sample-out cross-validation. The prediction rate for the proton nuclear magnetic resonance data by partial least-squares discriminant analysis with leave-one-sample-out cross-validation was also 100%. A new validation set of data was collected by flow-injection with ultraviolet spectroscopic detection two weeks later and predicted by partial least-squares discriminant analysis models constructed by the initial data representations with no parameter changes. The classification rates were 95% with the total ultraviolet absorbance chromatograms datasets and 100% with the other three datasets. Flow-injection with ultraviolet detection and proton nuclear magnetic resonance are simple, high throughput, and low-cost methods for discrimination studies.

NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.

PubMed

Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye B; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał

2016-06-28

An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine μ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find μ((207)Pb) = 0.59064 μN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of μ((207)Pb), in the range of 0.59000-0.59131 μN.

Electromagnetic theory of the nuclear interaction. Application to the deuteron {sup 2}H

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffer, Bernard

2012-06-20

Bieler of the Rutherford laboratory imagined in 1924 a magnetic attraction equilibrating an electrostatic repulsion between the protons. Since the discovery of the neutron and the magnetic moments of the nucleons proving that the neutron contains electric charges, nobody, as far as I know, has tried to apply electromagnetism to the nuclear interaction. The electrostatic and magnetic interactions are completely neglected except for a mean Coulomb repulsion. As it is well known, there is an attraction between an electric charge and a neutral conductor. In the neutron, the positive charges are repelled and the negative charges attracted by a nearbymore » proton. There is a net attraction explaining quantitatively the so-called strong force as it is shown in this paper. In the deuteron, the magnetic repulsion equilibrates the electrostatically induced neutron-proton attraction. The experimental value (- 2.2 MeV) is surrounded by - 1.6 MeV and - 2.5 MeV, depending on the calculation method. No arbitrary fitting parameter is used, only physical constants: it is a true ab initio calculation. The theoretical ratio between nuclear and chemical energies has been found to be (m{sub p}/m{sub e}{alpha}), proving that the usual assumption that the electromagnetic interaction is too feeble to predict the nuclear interaction is incorrect.« less

Structure and magnetic properties of SiO{sub 2}/PCL novel sol–gel organic–inorganic hybrid materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catauro, Michelina, E-mail: michelina.catauro@unina2.it; Bollino, Flavia; Cristina Mozzati, Maria

2013-07-15

Organic–inorganic nanocomposite materials have been synthesized via sol–gel. They consist of an inorganic SiO{sub 2} matrix, in which different percentages of poly(ε-caprolactone) (PCL) have been incorporated. The formation of H-bonds among the carbonyl groups of the polymer chains and Si–OH group of the inorganic matrix has been proved by means of Fourier transform infrared spectroscopy (FT-IR) analysis and has been confirmed by solid-state nuclear magnetic resonance (NMR). X-Ray diffraction (XRD) analysis highlighted the amorphous nature of the synthesized materials. Scanning electron microscope (SEM) micrograph and atomic force microscope (AFM) topography showed their homogeneous morphology and nanostructure nature. Considering the opportunitymore » to synthesize these hybrid materials under microgravity conditions by means of magnetic levitation, superconducting quantum interference device (SQUID) magnetometry has been used to quantify their magnetic susceptibility. This measure has shown that the SiO{sub 2}/PCL hybrid materials are diamagnetic and that their diamagnetic susceptibility is independent of temperature and increases with the PCL amount. - Graphical abstract: Characterization and magnetic properties of SiO{sub 2}/PCL organic–inorganic hybrid materials synthesized via sol–gel. FT-IR, Fourier transform infrared spectroscopy; solid-state NMR: solid-state nuclear magnetic resonance; SQUID: superconducting quantum interference device. - Highlights: • Sol–gel synthesis of SiO{sub 2}/PCL amorphous class I organic–inorganic hybrid materials. • FT-IR and NMR analyses show the hydrogen bonds formation between SiO{sub 2} and PCL. • AFM and SEM analyses confirm that the SiO{sub 2}/PCL are homogenous hybrid materials. • The SQUID measures show that the simples are diamagnetic. • Diamagnetic susceptibility of SiO{sub 2}/PCL materials increases with the PCL amount.« less

Chiral discrimination in nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Lazzeretti, Paolo

2017-11-01

Chirality is a fundamental property of molecules whose spatial symmetry is characterized by the absence of improper rotations, making them not superimposable to their mirror image. Chiral molecules constitute the elementary building blocks of living species and one enantiomer is favoured in general (e.g. L-aminoacids and D-sugars pervade terrestrial homochiral biochemistry) because most chemical reactions producing natural substances are enantioselective. Since the effect of chiral chemicals and drugs on living beings can be markedly different between enantiomers, the quest for practical spectroscopical methods to scrutinize chirality is an issue of great importance and interest. Nuclear magnetic resonance (NMR) is a topmost analytical technique, but spectrometers currently used are ‘blind’ to chirality, i.e. unable to discriminate the two mirror-image forms of a chiral molecule, because, in the absence of a chiral solvent, the spectral parameters, chemical shifts and spin-spin coupling constants are identical for enantiomers. Therefore, the development of new procedures for routine chiral recognition would offer basic support to scientists. However, in the presence of magnetic fields, a distinction between true and false chirality is mandatory. The former epitomizes natural optical activity, which is rationalized by a time-even pseudoscalar, i.e. the trace of a second-rank tensor, the mixed electric dipole/magnetic dipole polarizability. The Faraday effect, magnetic circular dichroism and magnetic optical activity are instead related to a time-odd axial vector. The present review summarizes recent theoretical and experimental efforts to discriminate enantiomers via NMR spectroscopy, with the focus on the deep connection between chirality and symmetry properties under the combined set of fundamental discrete operations, namely charge conjugation, parity (space inversion) and time (motion) reversal.

Nuclear Technology. Course 32: Nondestructive Examination (NDE) II. Module 32-3, Fundamentals of Magnetic Particle Testing.

ERIC Educational Resources Information Center

Groseclose, Richard

This third in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II explains the principles of magnets and magnetic fields and how they are applied in magnetic particle testing, describes the theory and methods of magnetizing test specimens, describes the test equipment used, discusses the principles and…

Research on stellarator-mirror fission-fusion hybrid

NASA Astrophysics Data System (ADS)

Moiseenko, V. E.; Kotenko, V. G.; Chernitskiy, S. V.; Nemov, V. V.; Ågren, O.; Noack, K.; Kalyuzhnyi, V. N.; Hagnestål, A.; Källne, J.; Voitsenya, V. S.; Garkusha, I. E.

2014-09-01

The development of a stellarator-mirror fission-fusion hybrid concept is reviewed. The hybrid comprises of a fusion neutron source and a powerful sub-critical fast fission reactor core. The aim is the transmutation of spent nuclear fuel and safe fission energy production. In its fusion part, neutrons are generated in deuterium-tritium (D-T) plasma, confined magnetically in a stellarator-type system with an embedded magnetic mirror. Based on kinetic calculations, the energy balance for such a system is analyzed. Neutron calculations have been performed with the MCNPX code, and the principal design of the reactor part is developed. Neutron outflux at different outer parts of the reactor is calculated. Numerical simulations have been performed on the structure of a magnetic field in a model of the stellarator-mirror device, and that is achieved by switching off one or two coils of toroidal field in the Uragan-2M torsatron. The calculations predict the existence of closed magnetic surfaces under certain conditions. The confinement of fast particles in such a magnetic trap is analyzed.

NMR at very low fields.

PubMed

Trahms, Lutz; Burghoff, Martin

2010-10-01

Although nuclear magnetic resonance in low fields around or below the Earth's magnetic field is almost as old as nuclear magnetic resonance itself, the recent years have experienced a revival of this technique that is opposed to the common trend towards higher and higher fields. The background of this development is the expectation that the low-field domain may open a new window for the study of molecular structure and dynamics. Here, we will give an overview on the specific features in the low-field domain, both from the technical and from the physical point of view. In addition, we present a short passage on the option of magnetic resonance imaging in fields of the micro-Tesla range. Copyright © 2010 Elsevier Inc. All rights reserved.

Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR

NASA Astrophysics Data System (ADS)

Zhang, Z. T.; Xu, C.; Dmytriieva, D.; Molatta, S.; Wosnitza, J.; Wang, Y. T.; Helm, M.; Zhou, Shengqiang; Kühne, H.

2017-11-01

We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13C nuclear spin-lattice relaxation rate 1/T1 by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of 1/T1 below about 10 K can well be described by a thermally activated form, \

Chiral Analysis by Tandem Mass Spectrometry Using the Kinetic Method, by Polarimetry, and by [Superscript 1]H NMR Spectroscopy

ERIC Educational Resources Information Center

Fedick, Patrick W.; Bain, Ryan M.; Bain, Kinsey; Cooks, R. Graham

2017-01-01

The goal of this laboratory exercise was for students to understand the concept of chirality and how enantiomeric excess (ee) is experimentally determined using the analysis of ibuprofen as an example. Students determined the enantiomeric excess of the analyte by three different instrumental methods: mass spectrometry, nuclear magnetic resonance…

An Introduction to Drug Discovery by Probing Protein-Substrate Interactions Using Saturation Transfer Difference-Nuclear Magnetic Resonance (STD-NMR)

ERIC Educational Resources Information Center

Guegan, Jean-Paul; Daniellou, Richard

2012-01-01

NMR spectroscopy is a powerful tool for characterizing and identifying molecules and nowadays is even used to characterize complex systems in biology. In the experiment presented here, students learned how to apply this modern technique to probe interactions between small molecules and proteins. With the use of simple organic synthesis, students…

Dynamic aspects of antibody:oligosaccharide complexes characterized by molecular dynamics simulations and saturation transfer difference nuclear magnetic resonance.

PubMed

Theillet, François-Xavier; Frank, Martin; Vulliez-Le Normand, Brigitte; Simenel, Catherine; Hoos, Sylviane; Chaffotte, Alain; Bélot, Frédéric; Guerreiro, Catherine; Nato, Farida; Phalipon, Armelle; Mulard, Laurence A; Delepierre, Muriel

2011-12-01

Carbohydrates are likely to maintain significant conformational flexibility in antibody (Ab):carbohydrate complexes. As demonstrated herein for the protective monoclonal Ab (mAb) F22-4 recognizing the Shigella flexneri 2a O-antigen (O-Ag) and numerous synthetic oligosaccharide fragments thereof, the combination of molecular dynamics simulations and nuclear magnetic resonance saturation transfer difference experiments, supported by physicochemical analysis, allows us to determine the binding epitope and its various contributions to affinity without using any modified oligosaccharides. Moreover, the methods used provide insights into ligand flexibility in the complex, thus enabling a better understanding of the Ab affinities observed for a representative set of synthetic O-Ag fragments. Additionally, these complementary pieces of information give evidence to the ability of the studied mAb to recognize internal as well as terminal epitopes of its cognate polysaccharide antigen. Hence, we show that an appropriate combination of computational and experimental methods provides a basis to explore carbohydrate functional mimicry and receptor binding. The strategy may facilitate the design of either ligands or carbohydrate recognition domains, according to needed improvements of the natural carbohydrate:receptor properties. © The Author 2011. Published by Oxford University Press. All rights reserved.

Proton Nuclear Magnetic Resonance Spectroscopy as a Technique for Gentamicin Drug Susceptibility Studies with Escherichia coli ATCC 25922

PubMed Central

García-Álvarez, Lara; Busto, Jesús H.; Avenoza, Alberto; Sáenz, Yolanda; Peregrina, Jesús Manuel

2015-01-01

Antimicrobial drug susceptibility tests involving multiple time-consuming steps are still used as reference methods. Today, there is a need for the development of new automated instruments that can provide faster results and reduce operating time, reagent costs, and labor requirements. Nuclear magnetic resonance (NMR) spectroscopy meets those requirements. The metabolism and antimicrobial susceptibility of Escherichia coli ATCC 25922 in the presence of gentamicin have been analyzed using NMR and compared with a reference method. Direct incubation of the bacteria (with and without gentamicin) into the NMR tube has also been performed, and differences in the NMR spectra were obtained. The MIC, determined by the reference method found in this study, would correspond with the termination of the bacterial metabolism observed with NMR. Experiments carried out directly into the NMR tube enabled the development of antimicrobial drug susceptibility tests to assess the effectiveness of the antibiotic. NMR is an objective and reproducible method for showing the effects of a drug on the subject bacterium and can emerge as an excellent tool for studying bacterial activity in the presence of different antibiotic concentrations. PMID:25972417

Proton Nuclear Magnetic Resonance Spectroscopy as a Technique for Gentamicin Drug Susceptibility Studies with Escherichia coli ATCC 25922.

PubMed

García-Álvarez, Lara; Busto, Jesús H; Avenoza, Alberto; Sáenz, Yolanda; Peregrina, Jesús Manuel; Oteo, José A

2015-08-01

Antimicrobial drug susceptibility tests involving multiple time-consuming steps are still used as reference methods. Today, there is a need for the development of new automated instruments that can provide faster results and reduce operating time, reagent costs, and labor requirements. Nuclear magnetic resonance (NMR) spectroscopy meets those requirements. The metabolism and antimicrobial susceptibility of Escherichia coli ATCC 25922 in the presence of gentamicin have been analyzed using NMR and compared with a reference method. Direct incubation of the bacteria (with and without gentamicin) into the NMR tube has also been performed, and differences in the NMR spectra were obtained. The MIC, determined by the reference method found in this study, would correspond with the termination of the bacterial metabolism observed with NMR. Experiments carried out directly into the NMR tube enabled the development of antimicrobial drug susceptibility tests to assess the effectiveness of the antibiotic. NMR is an objective and reproducible method for showing the effects of a drug on the subject bacterium and can emerge as an excellent tool for studying bacterial activity in the presence of different antibiotic concentrations. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Optically induced cross relaxation via nitrogen-related defects for bulk diamond 13C hyperpolarization

NASA Astrophysics Data System (ADS)

Wunderlich, Ralf; Kohlrautz, Jonas; Abel, Bernd; Haase, Jürgen; Meijer, Jan

2017-12-01

In this Rapid Communication we utilize nuclear magnetic resonance to investigate the hyperpolarization effect of negatively charged nitrogen vacancy (NV) centers on bulk 13C nuclei in a diamond single crystal. We were able to identify several polarization peaks of a different sign at different magnetic fields in a region of some tens of Gauss centered around 50 mT . The bulk 13C hyperpolarization in the investigated field range is usually attributed to the excited state level anticrossing of the NV center. However, we found that this bulk hyperpolarization is caused by optically induced cross relaxation and that it takes place in the NV center ground state. The four-spin coupling between the polarized NV electron spin, the electron spin of a substitutional nitrogen impurity (P1), as well as its 14N nuclei and the 13C nuclear spin have to be considered. We introduce a simple theoretical model which completely fits with the experimental data and which clearly shows that the P1 centers are involved in the polarization process. We expect that the current work has a significant impact on future NV-based polarization applications.

Towards Single Biomolecule Imaging via Optical Nanoscale Magnetic Resonance Imaging.

PubMed

Boretti, Alberto; Rosa, Lorenzo; Castelletto, Stefania

2015-09-09

Nuclear magnetic resonance (NMR) spectroscopy is a physical marvel in which electromagnetic radiation is charged and discharged by nuclei in a magnetic field. In conventional NMR, the specific nuclei resonance frequency depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms. NMR is routinely utilized in clinical tests by converting nuclear spectroscopy in magnetic resonance imaging (MRI) and providing 3D, noninvasive biological imaging. While this technique has revolutionized biomedical science, measuring the magnetic resonance spectrum of single biomolecules is still an intangible aspiration, due to MRI resolution being limited to tens of micrometers. MRI and NMR have, however, recently greatly advanced, with many breakthroughs in nano-NMR and nano-MRI spurred by using spin sensors based on an atomic impurities in diamond. These techniques rely on magnetic dipole-dipole interactions rather than inductive detection. Here, novel nano-MRI methods based on nitrogen vacancy centers in diamond are highlighted, that provide a solution to the imaging of single biomolecules with nanoscale resolution in-vivo and in ambient conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nuclear Magnetic Resonance Spectroscopy-Based Identification of Yeast.

PubMed

Himmelreich, Uwe; Sorrell, Tania C; Daniel, Heide-Marie

2017-01-01

Rapid and robust high-throughput identification of environmental, industrial, or clinical yeast isolates is important whenever relatively large numbers of samples need to be processed in a cost-efficient way. Nuclear magnetic resonance (NMR) spectroscopy generates complex data based on metabolite profiles, chemical composition and possibly on medium consumption, which can not only be used for the assessment of metabolic pathways but also for accurate identification of yeast down to the subspecies level. Initial results on NMR based yeast identification where comparable with conventional and DNA-based identification. Potential advantages of NMR spectroscopy in mycological laboratories include not only accurate identification but also the potential of automated sample delivery, automated analysis using computer-based methods, rapid turnaround time, high throughput, and low running costs.We describe here the sample preparation, data acquisition and analysis for NMR-based yeast identification. In addition, a roadmap for the development of classification strategies is given that will result in the acquisition of a database and analysis algorithms for yeast identification in different environments.

Ethanol determination in frozen fruit pulps: an application of quantitative nuclear magnetic resonance.

PubMed

da Silva Nunes, Wilian; de Oliveira, Caroline Silva; Alcantara, Glaucia Braz

2016-04-01

This study reports the chemical composition of five types of industrial frozen fruit pulps (acerola, cashew, grape, passion fruit and pineapple fruit pulps) and compares them with homemade pulps at two different stages of ripening. The fruit pulps were characterized by analyzing their metabolic profiles and determining their ethanol content using quantitative Nuclear Magnetic Resonance (qNMR). In addition, principal component analysis (PCA) was applied to extract more information from the NMR data. We detected ethanol in all industrial and homemade pulps; and acetic acid in cashew, grape and passion fruit industrial and homemade pulps. The ethanol content in some industrial pulps is above the level recommended by regulatory agencies and is near the levels of some post-ripened homemade pulps. This study demonstrates that qNMR can be used to rapidly detect ethanol content in frozen fruit pulps and food derivatives. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Tracking thermal degradation on passion fruit juice through Nuclear Magnetic Resonance and chemometrics.

PubMed

Soares, Marcia Valeria L; Alves Filho, Elenilson G; Silva, Lorena Mara A; Novotny, Etelvino Henrique; Canuto, Kirley Marques; Wurlitzer, Nedio Jair; Narain, Narendra; de Brito, Edy Sousa

2017-03-15

Thermal food processing mainly aims to control microorganism in order to extend its shelf life. However, it may induce chemical and nutritional changes in foodstuff. The Nuclear Magnetic Resonance (NMR) coupled to multivariate analysis was used to evaluate the effect of different thermal processing conditions (85 and 140°C for 4; 15; 30; and 60s) on the passion fruit juice using an Armfield pasteurizer. Through this approach it was possible to identify the changes in the juice composition. The temperature and the time lead to a hydrolysis of the sucrose to glucose and fructose. Additionally, juice submitted to 140°C for 60s results in the degradation of the sucrose and the formation of 5-(hydroxymethyl)-2-furfural (HMF). Despite no novel chemical marker has been identified, the 1 H NMR chemometrics approach may contribute in the choice of the temperature and time to be employed in the juice processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conformational ensembles of RNA oligonucleotides from integrating NMR and molecular simulations.

PubMed

Bottaro, Sandro; Bussi, Giovanni; Kennedy, Scott D; Turner, Douglas H; Lindorff-Larsen, Kresten

2018-05-01

RNA molecules are key players in numerous cellular processes and are characterized by a complex relationship between structure, dynamics, and function. Despite their apparent simplicity, RNA oligonucleotides are very flexible molecules, and understanding their internal dynamics is particularly challenging using experimental data alone. We show how to reconstruct the conformational ensemble of four RNA tetranucleotides by combining atomistic molecular dynamics simulations with nuclear magnetic resonance spectroscopy data. The goal is achieved by reweighting simulations using a maximum entropy/Bayesian approach. In this way, we overcome problems of current simulation methods, as well as in interpreting ensemble- and time-averaged experimental data. We determine the populations of different conformational states by considering several nuclear magnetic resonance parameters and point toward properties that are not captured by state-of-the-art molecular force fields. Although our approach is applied on a set of model systems, it is fully general and may be used to study the conformational dynamics of flexible biomolecules and to detect inaccuracies in molecular dynamics force fields.

A general nuclear magnetic resonance analysis of hetero-association of aromatic molecules in aqueous solution

NASA Astrophysics Data System (ADS)

Veselkov, Alexei N.; Evstigneev, Maxim P.; Veselkov, Dennis A.; Davies, David B.

2001-08-01

A general nuclear magnetic resonance analysis of a statistical-thermodynamical model of hetero-association of aromatic molecules in solution has been developed to take "edge effects" into consideration, i.e., the dependence of proton chemical shifts on the position of the molecule situated inside or at the edge of the aggregate. This generalized approach is compared with a previously published model, where an average contribution to proton shielding is considered irrespective of the position of the molecule in the stack. Association parameters have been determined from experimental concentration and temperature dependences of 500 MHz proton chemical shifts of the hetero-association of the acridine dye, proflavine, and the phenanthridinium dye, ethidium bromide, in aqueous solution. Differences in the parameters in the range 10%-30% calculated using the basic and generalized approaches have been found to depend substantially on the magnitude of the equilibrium hetero-association constant Khet—the larger the value of Khet, the higher the discrepancy between the two methods.

Increased reliability of nuclear magnetic resonance protein structures by consensus structure bundles.

PubMed

Buchner, Lena; Güntert, Peter

2015-02-03

Nuclear magnetic resonance (NMR) structures are represented by bundles of conformers calculated from different randomized initial structures using identical experimental input data. The spread among these conformers indicates the precision of the atomic coordinates. However, there is as yet no reliable measure of structural accuracy, i.e., how close NMR conformers are to the "true" structure. Instead, the precision of structure bundles is widely (mis)interpreted as a measure of structural quality. Attempts to increase precision often overestimate accuracy by tight bundles of high precision but much lower accuracy. To overcome this problem, we introduce a protocol for NMR structure determination with the software package CYANA, which produces, like the traditional method, bundles of conformers in agreement with a common set of conformational restraints but with a realistic precision that is, throughout a variety of proteins and NMR data sets, a much better estimate of structural accuracy than the precision of conventional structure bundles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Real-Time Monitoring of Chemical Changes in Three Kinds of Fermented Milk Products during Fermentation Using Quantitative Difference Nuclear Magnetic Resonance Spectroscopy.

PubMed

Lu, Yi; Ishikawa, Hiroto; Kwon, Yeondae; Hu, Fangyu; Miyakawa, Takuya; Tanokura, Masaru

2018-02-14

Fermented milk products are rising in popularity throughout the world as a result of their health benefits, including improving digestion, normalizing the function of the immune system, and aiding in weight management. This study applies an in situ quantitative nuclear magnetic resonance method to monitor chemical changes in three kinds of fermented milk products, Bulgarian yogurt, Caspian Sea yogurt, and kefir, during fermentation. As a result, the concentration changes in nine organic compounds, α/β-lactose, α/β-galactose, lactic acid, citrate, ethanol, lecithin, and creatine, were monitored in real time. This revealed three distinct metabolic processes in the three fermented milk products. Moreover, pH changes were also determined by variations in the chemical shift of citric acid during the fermentation processes. These results can be applied to estimate microbial metabolism in various flora and help guide the fermentation and storage of various fermented milk products to improve their quality, which may directly influence human health.

Large-Scale Computation of Nuclear Magnetic Resonance Shifts for Paramagnetic Solids Using CP2K.

PubMed

Mondal, Arobendo; Gaultois, Michael W; Pell, Andrew J; Iannuzzi, Marcella; Grey, Clare P; Hutter, Jürg; Kaupp, Martin

2018-01-09

Large-scale computations of nuclear magnetic resonance (NMR) shifts for extended paramagnetic solids (pNMR) are reported using the highly efficient Gaussian-augmented plane-wave implementation of the CP2K code. Combining hyperfine couplings obtained with hybrid functionals with g-tensors and orbital shieldings computed using gradient-corrected functionals, contact, pseudocontact, and orbital-shift contributions to pNMR shifts are accessible. Due to the efficient and highly parallel performance of CP2K, a wide variety of materials with large unit cells can be studied with extended Gaussian basis sets. Validation of various approaches for the different contributions to pNMR shifts is done first for molecules in a large supercell in comparison with typical quantum-chemical codes. This is then extended to a detailed study of g-tensors for extended solid transition-metal fluorides and for a series of complex lithium vanadium phosphates. Finally, lithium pNMR shifts are computed for Li 3 V 2 (PO 4 ) 3 , for which detailed experimental data are available. This has allowed an in-depth study of different approaches (e.g., full periodic versus incremental cluster computations of g-tensors and different functionals and basis sets for hyperfine computations) as well as a thorough analysis of the different contributions to the pNMR shifts. This study paves the way for a more-widespread computational treatment of NMR shifts for paramagnetic materials.

Probing Structural Changes among Analogous Inhibitor-Bound Forms of HIV-1 Protease and a Drug-Resistant Mutant in Solution by Nuclear Magnetic Resonance.

PubMed

Khan, Shahid N; Persons, John D; Paulsen, Janet L; Guerrero, Michel; Schiffer, Celia A; Kurt-Yilmaz, Nese; Ishima, Rieko

2018-03-13

In the era of state-of-the-art inhibitor design and high-resolution structural studies, detection of significant but small protein structural differences in the inhibitor-bound forms is critical to further developing the inhibitor. Here, we probed differences in HIV-1 protease (PR) conformation among darunavir and four analogous inhibitor-bound forms and compared them with a drug-resistant mutant using nuclear magnetic resonance chemical shifts. Changes in amide chemical shifts of wild-type (WT) PR among these inhibitor-bound forms, ΔCSP, were subtle but detectable and extended >10 Å from the inhibitor-binding site, asymmetrically between the two subunits of PR. Molecular dynamics simulations revealed differential local hydrogen bonding as the molecular basis of this remote asymmetric change. Inhibitor-bound forms of the drug-resistant mutant also showed a similar long-range ΔCSP pattern. Differences in ΔCSP values of the WT and the mutant (ΔΔCSPs) were observed at the inhibitor-binding site and in the surrounding region. Comparing chemical shift changes among highly analogous inhibitors and ΔΔCSPs effectively eliminated local environmental effects stemming from different chemical groups and enabled exploitation of these sensitive parameters to detect subtle protein conformational changes and to elucidate asymmetric and remote conformational effects upon inhibitor interaction.

Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sosnovsky, Denis V.; Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru; Novosibirsk State University, Pirogova 2, 630090, Novosibirsk

Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals andmore » radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign rules. Thus, LCs/LACs provide a consistent description of CIDNP in both liquids and solids with the prospect of exploiting it for the analysis of short-lived radicals and for optimizing the polarization level.« less

Detection of alterations in human sperm using magnetic orientation techniques

NASA Astrophysics Data System (ADS)

Sakhnini, Lama; Dairi, Maheen; Manaa, Hacene

2007-09-01

In this study we report on magnetic orientation of human sperms. Samples were taken from 17 donors. Normal human sperms became oriented with their long axis perpendicular to the magnetic field ( 1 Tesla maximum). Total orientation was achieved with magnetic field at about one Tesla, while for abnormal sperms the magnetic behavior was different. The dependence of the measured degree of orientation on the intensity of the magnetic field was in good agreement with the theoretical equation for the magnetic orientation of diamagnetic substances. As a result for a numerical analysis based on the equation, the anisotropic diamagnetic susceptibility of normal sperm was found to be ▵ χ= 8×10 -20 J/T2. The degree of orientation was influenced by the alterations in the shape of the head, body or the tail. It has been suggested that the DNA in the sperm head retain the strong magnetic anisotropy to counter balance the magnetic anisotropy retained by flagellum microtubules. Recent studies demonstrated a well-defined nuclear architecture in human sperm nucleus, where the head morphology has significant correlation with sperm chromatin structure assay SCSA. Then as the methods to evaluate SCSA can be difficult and expensive our simple magnetic orientation technique can be an alternative to diagnose alteration in DNA.

Phase diagram of Ba 2 NaOsO 6, a Mott insulator with strong spin orbit interactions

NASA Astrophysics Data System (ADS)

Liu, W.; Cong, R.; Garcia, E.; Reyes, A. P.; Lee, H. O.; Fisher, I. R.; Mitrović, V. F.

2018-05-01

We report 23Na nuclear magnetic resonance (NMR) measurements of the Mott insulator with strong spin-orbit interaction Ba2NaOsO6 as a function of temperature in different magnetic fields ranging from 7 T to 29 T. The measurements, intended to concurrently probe spin and orbital/lattice degrees of freedom, are an extension of our work at lower fields reported in Lu et al. (2017) [1]. We have identified clear quantitative NMR signatures that display the appearance of a canted ferromagnetic phase, which is preceded by local point symmetry breaking. We have compiled the field temperature phase diagram extending up to 29 T. We find that the broken local point symmetry phase extends over a wider temperature range as magnetic field increases.

Biological Ion Exchanger Resins

PubMed Central

Damadian, Raymond; Goldsmith, Michael; Zaner, K. S.

1971-01-01

Biological selectivity is shown to vary with medium osmotic strength and temperature. Selectivity reversals occur at 4°C and at an external osmolality of 0.800 indicating that intracellular hydration and endosolvent (intracellular water) structure are important determinants in selectivity. Magnetic resonance measurements of line width by steady-state nuclear magnetic resonance (NMR) indicate a difference in the intracellular water signal of 16 Hz between the K form and Na form of Escherichia coli, providing additional evidence that changes in the ionic composition of cells are accompanied by changes in endosolvent structure. The changes were found to be consistent with the thermodynamic and magnetic resonance properties of aqueous electrolyte solutions. Calculation of the dependence of ion-pairing forces on medium dielectric reinforces the role of endosolvent structure in determining ion exchange selectivity. PMID:4943653

Migration of Water in Litopenaeus Vannamei Muscle Following Freezing and Thawing.

PubMed

Deng, Qi; Wang, Yaling; Sun, Lijun; Li, Jianrong; Fang, Zhijia; Gooneratne, Ravi

2018-06-15

Water and protein are major constituents of shrimp, any changes in protein and the state of water influence the quality of shrimp. Therefore, a study to examine the law of moisture migration and protein denaturation under different freezing and thawing conditions is important. The proton density images of thawed frozen-shrimp revealed that the water loss during quick-freezing was much greater than that during slow freezing or microfreezing. At room temperature (25 °C), the water loss from brine-thawing was more than still-water thawing and still-water thawing was more than thawing spontaneously. Freezing-thawing resulted in uniform water redistribution in shrimp muscle. Nuclear magnetic resonance technology (low field magnetic imaging) was used to directly monitor the dynamic processes of fluidity state in shrimp and indirectly monitor protein denaturation and thereby determine the optimal method of freezing-thawing shrimp. Our research showed that microfreezing preservation minimized weight loss, juice leakage and protein denaturation in shrimp muscle during thawing. Water is one of the major components in most organs and is an important factor that influences the shrimp muscle quality. Water migration patterns and subsequent effects on the shrimp muscle under different freezing and thawing conditions were examined using low field nuclear magnetic resonance (NMR) technology. This research provides a theoretical foundation for shrimp processing plants to improve the freezing and thawing process to obtain optimal quality and flavor of shrimp products. © 2018 Institute of Food Technologists®.

Optically transmitted and inductively coupled electric reference to access in vivo concentrations for quantitative proton-decoupled ¹³C magnetic resonance spectroscopy.

PubMed

Chen, Xing; Pavan, Matteo; Heinzer-Schweizer, Susanne; Boesiger, Peter; Henning, Anke

2012-01-01

This report describes our efforts on quantification of tissue metabolite concentrations in mM by nuclear Overhauser enhanced and proton decoupled (13) C magnetic resonance spectroscopy and the Electric Reference To access In vivo Concentrations (ERETIC) method. Previous work showed that a calibrated synthetic magnetic resonance spectroscopy-like signal transmitted through an optical fiber and inductively coupled into a transmit/receive coil represents a reliable reference standard for in vivo (1) H magnetic resonance spectroscopy quantification on a clinical platform. In this work, we introduce a related implementation that enables simultaneous proton decoupling and ERETIC-based metabolite quantification and hence extends the applicability of the ERETIC method to nuclear Overhauser enhanced and proton decoupled in vivo (13) C magnetic resonance spectroscopy. In addition, ERETIC signal stability under the influence of simultaneous proton decoupling is investigated. The proposed quantification method was cross-validated against internal and external reference standards on human skeletal muscle. The ERETIC signal intensity stability was 100.65 ± 4.18% over 3 months including measurements with and without proton decoupling. Glycogen and unsaturated fatty acid concentrations measured with the ERETIC method were in excellent agreement with internal creatine and external phantom reference methods, showing a difference of 1.85 ± 1.21% for glycogen and 1.84 ± 1.00% for unsaturated fatty acid between ERETIC and creatine-based quantification, whereas the deviations between external reference and creatine-based quantification are 6.95 ± 9.52% and 3.19 ± 2.60%, respectively. Copyright © 2011 Wiley Periodicals, Inc.

Fictitious spin-12 operators and correlations in quadrupole nuclear spin system

NASA Astrophysics Data System (ADS)

Furman, G. B.; Goren, S. D.; Meerovich, V. M.; Sokolovsky, V. L.

The Hamiltonian and the spin operators for a spin 3/2 are represented in the basis formed by the Kronecker productions of the 2×2 Pauli matrices. This reformulation allows us to represent a spin 3/2 as a system of two coupled fictitious spins 1/2. Correlations between these fictitious spins are studied using well-developed methods. We investigate the temperature and field dependences of correlations, such as mutual information, classical correlations, entanglement, and geometric and quantum discords in the fictitious spin-1/2 system describing a nuclear spin 3/2 which is placed in magnetic and inhomogeneous electric fields. It is shown that the correlations between the fictitious spins demonstrate properties which differ from those of real two-spin systems. In contrast to real systems all the correlations between the fictitious spins do not vanish with increasing external magnetic field; at a high magnetic field the correlations tend to their limiting values. Classical correlations, quantum and geometric discords reveal a pronounced asymmetry relative to the measurements on subsystems (fictitious spins) even in a uniform magnetic field and at symmetrical EFG, η=0. The correlations depend also on the distribution of external charges, on the parameter of symmetry η. At η≠0 quantum and geometric discords have finite values in a zero magnetic field. The proposed approach may be useful in analysis of properties of particles with larger angular momentum, can provide the way to discover new physical phenomenon of quantum correlations, and can be a useful tool for similar definitions of other physical quantities of complex systems.

Quantitative magnetic resonance micro-imaging methods for pharmaceutical research.

PubMed

Mantle, M D

2011-09-30

The use of magnetic resonance imaging (MRI) as a tool in pharmaceutical research is now well established and the current literature covers a multitude of different pharmaceutically relevant research areas. This review focuses on the use of quantitative magnetic resonance micro-imaging techniques and how they have been exploited to extract information that is of direct relevance to the pharmaceutical industry. The article is divided into two main areas. The first half outlines the theoretical aspects of magnetic resonance and deals with basic magnetic resonance theory, the effects of nuclear spin-lattice (T(1)), spin-spin (T(2)) relaxation and molecular diffusion upon image quantitation, and discusses the applications of rapid magnetic resonance imaging techniques. In addition to the theory, the review aims to provide some practical guidelines for the pharmaceutical researcher with an interest in MRI as to which MRI pulse sequences/protocols should be used and when. The second half of the article reviews the recent advances and developments that have appeared in the literature concerning the use of quantitative micro-imaging methods to pharmaceutically relevant research. Copyright © 2010 Elsevier B.V. All rights reserved.

High Performance Nuclear Magnetic Resonance Imaging Using Magnetic Resonance Force Microscopy

DTIC Science & Technology

2013-12-12

Micron- Size Ferromagnet . Physical Review Letters, 92(3) 037205 (2004) [22] A. Z. Genack and A. G. Redeld. Theory of nuclear spin diusion in a...perform spatially resolved scanned probe studies of spin dynamics in nanoscale ensembles of few electron spins of varying size . Our research culminated...perform spatially resolved scanned probe studies of spin dynamics in nanoscale ensembles of few electron spins of varying size . Our research culminated

Nuclear Magnetic Resonance Shift Reagents: Abnormal 13C Shifts Produced by Complexation of Lanthanide Chelates with Saturated Amines and n-Butyl Isocyanide

PubMed Central

Marzin, Claude; Leibfritz, Dieter; Hawkes, Geoffrey E.; Roberts, John D.

1973-01-01

Lanthanide-induced shfits of 13C nuclear magnetic resonances are reported for several amines and n-butyl isocyanide. Contact contributions to such shifts, especially of β carbons, are clearly important for the chelates of Eu+3 and Pr+3. The importance of contact terms is shown to change in a rather predictable manner with the structure of the amine. PMID:16592062

Gauge-origin independent formalism of two-component relativistic framework based on unitary transformation in nuclear magnetic shielding constant

NASA Astrophysics Data System (ADS)

Hayami, Masao; Seino, Junji; Nakai, Hiromi

2018-03-01

This article proposes a gauge-origin independent formalism of the nuclear magnetic shielding constant in the two-component relativistic framework based on the unitary transformation. The proposed scheme introduces the gauge factor and the unitary transformation into the atomic orbitals. The two-component relativistic equation is formulated by block-diagonalizing the Dirac Hamiltonian together with gauge factors. This formulation is available for arbitrary relativistic unitary transformations. Then, the infinite-order Douglas-Kroll-Hess (IODKH) transformation is applied to the present formulation. Next, the analytical derivatives of the IODKH Hamiltonian for the evaluation of the nuclear magnetic shielding constant are derived. Results obtained from the numerical assessments demonstrate that the present formulation removes the gauge-origin dependence completely. Furthermore, the formulation with the IODKH transformation gives results that are close to those in four-component and other two-component relativistic schemes.

Electric field gradient in FeTiO3 by nuclear magnetic resonance and ab initio calculations.

PubMed

Procházka, V; Stěpánková, H; Chlan, V; Tuček, J; Cuda, J; Kouřil, K; Filip, J; Zbořil, R

2011-05-25

Temperature dependence of nuclear magnetic resonance (NMR) spectra of (47)Ti and (49)Ti in polycrystalline ilmenite FeTiO(3) was measured in the range from 5 to 300 K under an external magnetic field of 9.401 T. NMR spectra collected between 300 and 77 K exhibit a resolved quadrupole splitting. The electric field gradient (EFG) tensor was evaluated for Ti nuclei and the ratio of (47)Ti and (49)Ti nuclear quadrupole moments was refined during the fitting procedure. Below 77 K, the fine structure of quadrupole splitting disappears due to the enormous increase of anisotropy. As a counterpart, ab initio calculations were performed using full potential augmented plane waves + local orbitals. The calculated EFG tensors for Ti and Fe were compared to the experimental ones evaluated from NMR and the Mössbauer spectroscopy experiments.

Dynamic signatures of the transition from stacking disordered to hexagonal ice: Dielectric and nuclear magnetic resonance studies

NASA Astrophysics Data System (ADS)

Gainaru, C.; Vynokur, E.; Köster, K. W.; Fuentes-Landete, V.; Spettel, N.; Zollner, J.; Loerting, T.; Böhmer, R.

2018-04-01

Using various temperature-cycling protocols, the dynamics of ice I were studied via dielectric spectroscopy and nuclear magnetic resonance relaxometry on protonated and deuterated samples obtained by heating high-density amorphous ices as well as crystalline ice XII. Previous structural studies of ice I established that at temperatures of about 230 K, the stacking disorder of the cubic/hexagonal oxygen lattice vanishes. The present dielectric and nuclear magnetic resonance investigations of spectral changes disclose that the memory of the existence of a precursor phase is preserved in the hydrogen matrix up to 270 K. This finding of hydrogen mobility lower than that of the undoped hexagonal ice near the melting point highlights the importance of dynamical investigations of the transitions between various ice phases and sheds new light on the dynamics in ice I in general.

New Nuclear Magnetic Moment of ^{209}Bi: Resolving the Bismuth Hyperfine Puzzle.

PubMed

Skripnikov, Leonid V; Schmidt, Stefan; Ullmann, Johannes; Geppert, Christopher; Kraus, Florian; Kresse, Benjamin; Nörtershäuser, Wilfried; Privalov, Alexei F; Scheibe, Benjamin; Shabaev, Vladimir M; Vogel, Michael; Volotka, Andrey V

2018-03-02

A recent measurement of the hyperfine splitting in the ground state of Li-like ^{208}Bi^{80+} has established a "hyperfine puzzle"-the experimental result exhibits a 7σ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017)NCAOBW2041-172310.1038/ncomms15484; J. P. Karr, Nat. Phys. 13, 533 (2017)NPAHAX1745-247310.1038/nphys4159]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (μ_{I}) of ^{209}Bi. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of μ_{I}(^{209}Bi) and combine it with nuclear magnetic resonance measurements of Bi(NO_{3})_{3} in nitric acid solutions and of the hexafluoridobismuthate(V) BiF_{6}^{-} ion in acetonitrile. The result clearly reveals that μ_{I}(^{209}Bi) is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.

New Nuclear Magnetic Moment of 209Bi: Resolving the Bismuth Hyperfine Puzzle

NASA Astrophysics Data System (ADS)

Skripnikov, Leonid V.; Schmidt, Stefan; Ullmann, Johannes; Geppert, Christopher; Kraus, Florian; Kresse, Benjamin; Nörtershäuser, Wilfried; Privalov, Alexei F.; Scheibe, Benjamin; Shabaev, Vladimir M.; Vogel, Michael; Volotka, Andrey V.

2018-03-01

A recent measurement of the hyperfine splitting in the ground state of Li-like 80+208Bi has established a "hyperfine puzzle"—the experimental result exhibits a 7 σ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017), 10.1038/ncomms15484; J. P. Karr, Nat. Phys. 13, 533 (2017), 10.1038/nphys4159]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (μI) of 209Bi. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of μI(209ipts>) and combine it with nuclear magnetic resonance measurements of Bi (NO3 )3 in nitric acid solutions and of the hexafluoridobismuthate(V) BiF6- ion in acetonitrile. The result clearly reveals that μI(209Bi) is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.

Neutron powder diffraction refinement of the nuclear and magnetic structures of HoNi{sub 2}B{sub 2}C at R.T., 10, 5.1, and 2.2 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Q.; Grigereit, T.E.; Lynn, J.W.

The nuclear and magnetic structures of HoNi{sub 2}B{sub 2}C have been investigated by neutron powder diffraction at room temperature and at 10, 5.1 and 2.2K. The compound crystallizes with the symmetry of space group 14/mmm and has room temperature lattice parameters a = 3.5170(1) and c = 10.5217(3) {angstrom}. No phase transitions of the nuclear structure have been observed in the range of temperatures examined. Magnetic peaks begin to appear at about 8K. The magnetic structure is the superposition of two configurations, one in which ferromagnetic sheets of holmium spins parallel to the a-b plane are coupled antiferromagnetically along themore » c-axis, and another in which the ferromagnetic planes are rotated away from the antiparallel configuration to give an incommensurate helicoidal structure with a period approximately equal to twelve times the length of the c-axis. The helicoidal structure competes with superconductivity while the antiferromagnetism coexists with it.« less

Evidence for weak ferromagnetism, isostructural phase transition, and linear magnetoelectric coupling in the multiferroic Bi0.8Pb0.2Fe0.9Nb0.1O3 solid solution

NASA Astrophysics Data System (ADS)

Patel, Jay Prakash; Senyshyn, Anatoliy; Fuess, Hartmut; Pandey, Dhananjai

2013-09-01

Magnetization, dielectric, and calorimetric studies on Bi0.8 Pb0.2 Fe0.9 Nb0.1O3 (BF-0.2PFN) reveal very weak ferromagnetism but strong dielectric anomaly at the antiferromagnetic transition temperature (TN) characteristic of magnetoelectric coupling. We correlate these results with nuclear and magnetic structure studies using x-ray and neutron powder diffraction techniques, respectively. Rietveld refinements using x-ray powder diffraction data in the temperature range 300 to 673 K reveal pronounced anomalies in the unit cell parameters at TN, indicating strong magnetoelastic coupling. The nuclear and magnetic structures of BF-0.2PFN were determined from neutron powder diffraction data using a representation theory approach. They show the occurrence of a first-order isostructural phase transition (IPT) accompanying the magnetic ordering below TN˜566 K, leading to significant discontinuous change in the ionic polarization (ΔPz˜1.6(3) μC/cm2) and octahedral tilt angle (˜0.3°) at TN. The ionic polarization obtained from refined positional coordinates of the nuclear structure and Born effective charges is shown to scale linearly with sublattice magnetization, confirming the presence of linear magnetoelectric coupling in BF-0.2PFN at the atomic level, despite the very low value of remanent magnetization (Mr).

Ab initio NMR parameters of BrCH3 and ICH3 with relativistic and vibrational corrections

NASA Astrophysics Data System (ADS)

Uhlíková, Tereza; Urban, Štěpán

2018-05-01

This study is focused on two effects identified when NMR parameters are calculated based on first principles. These effects are 1. vibrational correction of properties when using ab initio optimized equilibrium geometry; 2. relativistic effects and limits of using the Flygare equation. These effects have been investigated and determined for nuclear spin-rotation constants and nuclear magnetic shieldings for the CH3Br and CH3I molecules. The most significant result is the difference between chemical shieldings determined based on the ab initio relativistic four-component Dirac-Coulomb Hamiltonian and chemical shieldings calculated using experimental values and the Flygare equation. This difference is approximately 320 ppm and 1290 ppm for 79Br and 127I in the CH3X molecule, respectively.

Room-temperature coupling between electrical current and nuclear spins in OLEDs

NASA Astrophysics Data System (ADS)

Malissa, H.; Kavand, M.; Waters, D. P.; van Schooten, K. J.; Burn, P. L.; Vardeny, Z. V.; Saam, B.; Lupton, J. M.; Boehme, C.

2014-09-01

The effects of external magnetic fields on the electrical conductivity of organic semiconductors have been attributed to hyperfine coupling of the spins of the charge carriers and hydrogen nuclei. We studied this coupling directly by implementation of pulsed electrically detected nuclear magnetic resonance spectroscopy in organic light-emitting diodes (OLEDs). The data revealed a fingerprint of the isotope (protium or deuterium) involved in the coherent spin precession observed in spin-echo envelope modulation. Furthermore, resonant control of the electric current by nuclear spin orientation was achieved with radiofrequency pulses in a double-resonance scheme, implying current control on energy scales one-millionth the magnitude of the thermal energy.

An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

NASA Technical Reports Server (NTRS)

De, B. R.; Srnka, L. J.

1978-01-01

Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

Nematicity and magnetism in LaFeAsO single crystals probed by 75As nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Ok, J. M.; Baek, S.-H.; Efremov, D. V.; Kappenberger, R.; Aswartham, S.; Kim, J. S.; van den Brink, Jeroen; Büchner, B.

2018-05-01

We report a 75As nuclear magnetic resonance study in LaFeAsO single crystals, which undergoes nematic and antiferromagnetic transitions at Tnem˜156 K and TN˜138 K, respectively. Below Tnem, the 75As spectrum splits sharply into two for an external magnetic field parallel to the orthorhombic a or b axis in the FeAs planes. Our analysis of the data demonstrates that the NMR line splitting arises from an electronically driven rotational symmetry breaking. The 75As spin-lattice relaxation rate as a function of temperature shows that spin fluctuations are strongly enhanced just below Tnem. These NMR findings indicate that nematic order promotes spin fluctuations in magnetically ordered LaFeAsO, as observed in nonmagnetic and superconducting FeSe. We conclude that the origin of nematicity is identical in both FeSe and LaFeAsO regardless of whether or not a long-range magnetic order develops in the nematic state.

Numerical study of the magnetized friction force

NASA Astrophysics Data System (ADS)

Fedotov, A. V.; Bruhwiler, D. L.; Sidorin, A. O.; Abell, D. T.; Ben-Zvi, I.; Busby, R.; Cary, J. R.; Litvinenko, V. N.

2006-07-01

Fundamental advances in experimental nuclear physics will require ion beams with orders of magnitude luminosity increase and temperature reduction. One of the most promising particle accelerator techniques for achieving these goals is electron cooling, where the ion beam repeatedly transfers thermal energy to a copropagating electron beam. The dynamical friction force on a fully ionized gold ion moving through magnetized and unmagnetized electron distributions has been simulated, using molecular dynamics techniques that resolve close binary collisions. We present a comprehensive examination of theoretical models in use by the electron cooling community. Differences in these models are clarified, enabling the accurate design of future electron cooling systems for relativistic ion accelerators.

Influence of the nuclear Zeeman effect on mode locking in pulsed semiconductor quantum dots

NASA Astrophysics Data System (ADS)

Beugeling, Wouter; Uhrig, Götz S.; Anders, Frithjof B.

2017-09-01

The coherence of the electron spin in a semiconductor quantum dot is strongly enhanced by mode locking through nuclear focusing, where the synchronization of the electron spin to periodic pulsing is slowly transferred to the nuclear spins of the semiconductor material, mediated by the hyperfine interaction between these. The external magnetic field that drives the Larmor oscillations of the electron spin also subjects the nuclear spins to a Zeeman-like coupling, albeit a much weaker one. For typical magnetic fields used in experiments, the energy scale of the nuclear Zeeman effect is comparable to that of the hyperfine interaction, so that it is not negligible. In this work, we analyze the influence of the nuclear Zeeman effect on mode locking quantitatively. Within a perturbative framework, we calculate the Overhauser-field distribution after a prolonged period of pulsing. We find that the nuclear Zeeman effect can exchange resonant and nonresonant frequencies. We distinguish between models with a single type and with multiple types of nuclei. For the latter case, the positions of the resonances depend on the individual g factors, rather than on the average value.

Nuclear Magnetic Resonance (NMR) as a tool for the study of the metabolism of Rickettsia slovaca.

PubMed

García-Álvarez, Lara; Busto, Jesús H; Peregrina, Jesús M; Santibáñez, Sonia; Portillo, Aránzazu; Avenoza, Alberto; Oteo, José A

2015-01-01

Rickettsial infections are caused by intracellular bacteria. They do not grow in standard culture media so there are limitations in routine practice to study their metabolism. Nuclear Magnetic Resonance (NMR) spectroscopy is used for identification of metabolites in biological samples. Vero cells infected with Rickettsia slovaca as well as uninfected cells were monitored by (1)H NMR showing the presence of ethanol and lactic acid. As no differences were observed, labeled compounds were added into cultures. When D-[1-13C]glucose was monitored by (13)C NMR no differences among infected and uninfected cells were observed in metabolic profiles. Glucose was transformed into ethanol in all cultures. Monitored experiments carried out with [2-13C]glycine showed differences between infected and uninfected cell cultures spectra. Glycine was partially transformed into serine, but the amount of the serine formed was larger in those infected. Moreover, L-[2-13C]leucine, L-[1-13C]isoleucine and L-[15N]tyrosine were evaluated. No differences among infected and uninfected cells were observed in the metabolic profiles when tyrosine and leucine were monitored. The amino acid L-[1-13C]isoleucine exhibited different metabolism in presence of the R. slovaca, showing a promising behavior as biomarker. In this work we focused on finding one or more compounds that could be metabolized specifically by R. slovaca and could be used as an indicator of its activity. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Anomalous electron spin decoherence in an optically pumped quantum dot

NASA Astrophysics Data System (ADS)

Shi, Xiaofeng; Sham, L. J.

2013-03-01

We study the nuclear-spin-fluctuation induced spin decoherence of an electron (SDE) in an optically pumped quantum dot. The SDE is computed in terms of the steady distribution of the nuclear field (SDNF) formed through the hyperfine interaction (HI) with two different nuclear species in the dot. A feedback loop between the optically driven electron spin and the nuclear spin ensemble determines the SDNF [W. Yang and L. J. Sham, Phy. Rev. B 85, 235319(2012)]. Different from that work and others reviewed therein, where a bilinear HI, SαIβ , between the electron (or hole) spin S and the nuclear spin I is used, we use an effective nonlinear interaction of the form SαIβIγ derived from the Fermi-contact HI. Our feedback loop forms a multi-peak SDNF in which the SDE shows remarkable collapses and revivals in nanosecond time scale. Such an anomalous SDE results from a quantum interference effect of the electron Larmor precession in a multi-peak effective magnetic field. In the presence of a bilinear HI that suppresses the nuclear spin fluctuation, the non-Markovian SDE persists whenever there are finite Fermi contact interactions between two or more kinds of nuclei and the electron in the quantum dot. This work is supported by NSF(PHY 1104446) and the US Army Research Office MURI award W911NF0910406.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Seong-Joo, E-mail: sj.lee@kriss.re.kr; Shim, Jeong Hyun; Kim, Kiwoong

A strong pre-polarization field, usually tenths of a milli-tesla in magnitude, is used to increase the signal-to-noise ratio in ordinary superconducting quantum interference device-based nuclear magnetic resonance/magnetic resonance imaging experiments. Here, we introduce an experimental approach using two techniques to remove the need for the pre-polarization field. A dynamic nuclear polarization (DNP) technique enables us to measure an enhanced resonance signal. In combination with a π/2 pulse to avoid the Bloch-Siegert effect in a micro-tesla field, we obtained an enhanced magnetic resonance image by using DNP technique with a 34.5 μT static external magnetic field without field cycling. In this approach,more » the problems of eddy current and flux trapping in the superconducting pickup coil, both due to the strong pre-polarization field, become negligible.« less

Silicon Nanoparticles as Hyperpolarized Magnetic Resonance Imaging Agents

PubMed Central

Aptekar, Jacob W.; Cassidy, Maja C.; Johnson, Alexander C.; Barton, Robert A.; Lee, Menyoung; Ogier, Alexander C.; Vo, Chinh; Anahtar, Melis N.; Ren, Yin; Bhatia, Sangeeta N.; Ramanathan, Chandrasekhar; Cory, David G.; Hill, Alison L.; Mair, Ross W.; Rosen, Matthew S.; Walsworth, Ronald L.

2014-01-01

Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in-vivo applications of pre-hyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications. PMID:19950973

Silicon nanoparticles as hyperpolarized magnetic resonance imaging agents.

PubMed

Aptekar, Jacob W; Cassidy, Maja C; Johnson, Alexander C; Barton, Robert A; Lee, Menyoung; Ogier, Alexander C; Vo, Chinh; Anahtar, Melis N; Ren, Yin; Bhatia, Sangeeta N; Ramanathan, Chandrasekhar; Cory, David G; Hill, Alison L; Mair, Ross W; Rosen, Matthew S; Walsworth, Ronald L; Marcus, Charles M

2009-12-22

Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in vivo applications of prehyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications.

Evidence for Spin Singlet Pairing with Strong Uniaxial Anisotropy in URu2Si2 Using Nuclear Magnetic Resonance

NASA Astrophysics Data System (ADS)

Hattori, T.; Sakai, H.; Tokunaga, Y.; Kambe, S.; Matsuda, T. D.; Haga, Y.

2018-01-01

In order to identify the spin contribution to superconducting pairing compatible with the so-called "hidden order", Si 29 nuclear magnetic resonance measurements have been performed using a high-quality single crystal of URu2 Si2 . A clear reduction of the Si 29 Knight shift in the superconducting state has been observed under a magnetic field applied along the crystalline c axis, corresponding to the magnetic easy axis. These results provide direct evidence for the formation of spin-singlet Cooper pairs. Consequently, results indicating a very tiny change of the in-plane Knight shift reported previously demonstrate extreme uniaxial anisotropy for the spin susceptibility in the hidden order state.

Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

NASA Astrophysics Data System (ADS)

Weber, Stefan; Kothe, Gerd; Norris, James R.

1997-04-01

The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave radiation. Here, the laser pulse merely defines the beginning of the microwave-induced coherent time evolution. This second mechanism appears the most consistent with current experimental observations.

Probing a chemical compass: novel variants of low-frequency reaction yield detected magnetic resonance.

PubMed

Maeda, Kiminori; Storey, Jonathan G; Liddell, Paul A; Gust, Devens; Hore, P J; Wedge, C J; Timmel, Christiane R

2015-02-07

We present a study of a carotenoid-porphyrin-fullerene triad previously shown to function as a chemical compass: the photogenerated carotenoid-fullerene radical pair recombines at a rate sensitive to the orientation of an applied magnetic field. To characterize the system we develop a time-resolved Low-Frequency Reaction Yield Detected Magnetic Resonance (tr-LF-RYDMR) technique; the effect of varying the relative orientation of applied static and 36 MHz oscillating magnetic fields is shown to be strongly dependent on the strength of the oscillating magnetic field. RYDMR is a diagnostic test for involvement of the radical pair mechanism in the magnetic field sensitivity of reaction rates or yields, and has previously been applied in animal behavioural experiments to verify the involvement of radical-pair-based intermediates in the magnetic compass sense of migratory birds. The spectroscopic selection rules governing RYDMR are well understood at microwave frequencies for which the so-called 'high-field approximation' is valid, but at lower frequencies different models are required. For example, the breakdown of the rotating frame approximation has recently been investigated, but less attention has so far been given to orientation effects. Here we gain physical insights into the interplay of the different magnetic interactions affecting low-frequency RYDMR experiments performed in the challenging regime in which static and oscillating applied magnetic fields as well as internal electron-nuclear hyperfine interactions are of comparable magnitude. Our observations aid the interpretation of existing RYDMR-based animal behavioural studies and will inform future applications of the technique to verify and characterize further the biological receptors involved in avian magnetoreception.

High polarization of nuclear spins mediated by nanoparticles at millikelvin temperatures.

PubMed

Owers-Bradley, John R; Horsewill, Anthony J; Peat, David T; Goh, Kelvin S K; Gadian, David G

2013-07-07

Nuclear magnetic resonance (NMR) techniques are extensively used in many areas of basic and clinical research, as well as in diagnostic medicine. However, NMR signals are intrinsically weak, and this imposes substantial constraints on the amounts and concentrations of materials that can be detected. The signals are weak because of the low energies characteristic of NMR and the resulting very low (typically 0.0001-0.01%) polarization of the nuclear spins. Here, we show that exposure to very low temperatures and high magnetic fields, in conjunction with nanoparticle-mediated relaxation enhancement, can be used to generate extremely high nuclear polarization levels on a realistic timescale; with copper nanoparticles at 15 mK and 14 T, (13)C polarization grew towards its equilibrium level of 23% with an estimated half-time of about 60 hours. This contrasts with a (13)C half-time of at least one year in the presence of aluminium nanoparticles. Cupric oxide nanoparticles were also effective relaxation agents. Our findings lead us to suspect that the relaxation may be mediated, at least in part, by the remarkable magnetic properties that some nanoparticle preparations can display. This methodology offers prospects for achieving polarization levels of 10-50% or more for many nuclear species, with a wide range of potential applications in structural biology and medicine.

Quantitative Determination of Wax Contamination in Polystyrene HIPE Foam Using Solid-State NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cluff, Kyle James; Goodwin, Lynne Alese; Hamilton, Christopher Eric

Differences in molecular mobility between polystyrene foam and Brij-78 wax results in vast differences in the 1H nuclear magnetic resonance (NMR) linewidth. This allows for the convenient determination of wax content in the polystyrene foam components of inertial confinement fusion targets via solid-state NMR. Lastly, contamination levels as low as 0.1% are easily recognized and quantified, and the detection limit is calculated to be 0.02% even when only 32 transients are recorded.

Quantitative Determination of Wax Contamination in Polystyrene HIPE Foam Using Solid-State NMR

DOE PAGES

Cluff, Kyle James; Goodwin, Lynne Alese; Hamilton, Christopher Eric; ...

2017-11-29

Differences in molecular mobility between polystyrene foam and Brij-78 wax results in vast differences in the 1H nuclear magnetic resonance (NMR) linewidth. This allows for the convenient determination of wax content in the polystyrene foam components of inertial confinement fusion targets via solid-state NMR. Lastly, contamination levels as low as 0.1% are easily recognized and quantified, and the detection limit is calculated to be 0.02% even when only 32 transients are recorded.

Neutron polarization analysis study of the frustrated magnetic ground state of β-Mn1-xAlx

NASA Astrophysics Data System (ADS)

Stewart, J. R.; Andersen, K. H.; Cywinski, R.

2008-07-01

We have performed a neutron polarization analysis study of the short-range nuclear and magnetic correlations present in the dilute alloy, β-Mn1-xAlx with 0.03≤x≤0.16 , in order to study the evolution of the magnetic ground state of this system as it achieves static spin-glass order at concentrations x>0.09 . To this end we have developed a reverse-Monte Carlo algorithm which has enabled us to extract Warren-Cowley nuclear short-range order parameters and magnetic spin correlations. Using conventional neutron powder diffraction, we show that the nonmagnetic Al substituents preferentially occupy the magnetic site II Wyckoff positions in the β-Mn structure—resulting in a reduction of the magnetic topological frustration of the Mn atoms. These Al impurities are found to display strong anticlustering behavior. The magnetic spin correlations are predominantly antiferromagnetic, persisting over a short range which is similar for all the samples studied—above and below the spin-liquid-spin-glass boundary—while the observed static (disordered) moment is shown to increase with increasing Al concentration.

NMR evidence of charge fluctuations in multiferroic CuBr2

NASA Astrophysics Data System (ADS)

Wang, Rui-Qi; Zheng, Jia-Cheng; Chen, Tao; Wang, Peng-Shuai; Zhang, Jin-Shan; Cui, Yi; Wang, Chao; Li, Yuan; Xu, Sheng; Yuan, Feng; Yu, Wei-Qiang

2018-03-01

We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance (NQR), and zero-field nuclear magnetic resonance (NMR) measurements on single crystals of multiferroics CuBr2. High quality of the sample is demonstrated by the sharp magnetic and magnetic-driven ferroelectric transition at {T}{{N}}={T}{{C}}≈ 74 K. The zero-field 79Br and 81Br NMR are resolved below T N. The spin-lattice relaxation rates reveal charge fluctuations when cooled below 60 K. Evidences of an increase of NMR linewidth, a reduction of dielectric constant, and an increase of magnetic susceptibility are also seen at low temperatures. These data suggest an emergent instability which competes with the spiral magnetic ordering and the ferroelectricity. Candidate mechanisms are discussed based on the quasi-one-dimensional nature of the magnetic system. Project supported by the Ministry of Science and Technology of China (Grant No. 2016YFA0300504), the National Natural Science Foundation of China (Grant No. 11374364), the Fundamental Research Funds for the Central Universities of China, and the Research Funds of Renmin University, China (Grant No. 14XNLF08).

Dependence of magnetic field and electronic transport of Mn4 Single-molecule magnet in a Single-Electron Transistor

NASA Astrophysics Data System (ADS)

Rodriguez, Alvar; Singh, Simranjeet; Haque, Firoze; Del Barco, Enrique; Nguyen, Tu; Christou, George

2012-02-01

Dependence of magnetic field and electronic transport of Mn4 Single-molecule magnet in a Single-Electron Transistor A. Rodriguez, S. Singh, F. Haque and E. del Barco Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 USA T. Nguyen and G. Christou Department of Chemistry, University of Florida, Gainesville, Florida 32611 USA Abstract We have performed single-electron transport measurements on a series of Mn-based low-nuclearity single-molecule magnets (SMM) observing Coulomb blockade. SMMs with well isolated and low ground spin states, i.e. S = 9/2 (Mn4) and S = 6 (Mn3) were chosen for these studies, such that the ground spin multiplet does not mix with levels of other excited spin states for the magnetic fields (H = 0-8 T) employed in the experiments. Different functionalization groups were employed to change the mechanical, geometrical and transport characteristics of the molecules when deposited from liquid solution on the transistors. Electromigration-broken three-terminal single-electron transistors were used. Results obtained at temperatures down to 240 mK and in the presence of high magnetic fields will be shown.

Magnetoresistive biosensors for quantitative proteomics

NASA Astrophysics Data System (ADS)

Zhou, Xiahan; Huang, Chih-Cheng; Hall, Drew A.

2017-08-01

Quantitative proteomics, as a developing method for study of proteins and identification of diseases, reveals more comprehensive and accurate information of an organism than traditional genomics. A variety of platforms, such as mass spectrometry, optical sensors, electrochemical sensors, magnetic sensors, etc., have been developed for detecting proteins quantitatively. The sandwich immunoassay is widely used as a labeled detection method due to its high specificity and flexibility allowing multiple different types of labels. While optical sensors use enzyme and fluorophore labels to detect proteins with high sensitivity, they often suffer from high background signal and challenges in miniaturization. Magnetic biosensors, including nuclear magnetic resonance sensors, oscillator-based sensors, Hall-effect sensors, and magnetoresistive sensors, use the specific binding events between magnetic nanoparticles (MNPs) and target proteins to measure the analyte concentration. Compared with other biosensing techniques, magnetic sensors take advantage of the intrinsic lack of magnetic signatures in biological samples to achieve high sensitivity and high specificity, and are compatible with semiconductor-based fabrication process to have low-cost and small-size for point-of-care (POC) applications. Although still in the development stage, magnetic biosensing is a promising technique for in-home testing and portable disease monitoring.

Moisture in untreated, acetylated, and furfurylated Norway Spruce monitored during drying below fiber saturation using time domain NMR

Treesearch

Lisbeth G. Thygesen; Thomas Elder

2009-01-01

Using time domain–nuclear magnetic resonance spectroscopy, the moisture content (MC) in Norway spruce [Picea abies (L.) Karst.] sapwood, subjected to three different treatments (untreated, acetylated, and furfurylated), was studied during drying at 40oC at MCs below fiber saturation. Spin–spin relaxation time distributions were derived from Carr-Purcell-...

Chemical Principles Revisited. Proton Magnetic Resonance Spectroscopy.

ERIC Educational Resources Information Center

McQuarrie, Donald A.

1988-01-01

Discusses how to interpret nuclear magnetic resonance (NMR) spectra and how to use them to determine molecular structures. This discussion is limited to spectra that are a result of observation of only the protons in a molecule. This type is called proton magnetic resonance (PMR) spectra. (CW)

Local structures of mesoporous bioactive glasses and their surface alterations in vitro: inferences from solid-state nuclear magnetic resonance

PubMed Central

Gunawidjaja, Philips N.; Mathew, Renny; Lo, Andy Y. H.; Izquierdo-Barba, Isabel; García, Ana; Arcos, Daniel; Mattias Edén, María Vallet-Regí

2012-01-01

We review the benefits of using 29Si and 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy for probing the local structures of both bulk and surface portions of mesoporous bioactive glasses (MBGs) of the CaO–SiO2−(P2O5) system. These mesoporous materials exhibit an ordered pore arrangement, and are promising candidates for improved bone and tooth implants. We discuss experimental MAS NMR results from three MBGs displaying different Ca, Si and P contents: the 29Si NMR spectra were recorded either directly by employing radio-frequency pulses to 29Si, or by magnetization transfers from neighbouring protons using cross polarization, thereby providing quantitative information about the silicate speciation present in the pore wall and at the MBG surface, respectively. The surface modifications were monitored for the three MBGs during their immersion in a simulated body fluid (SBF) for intervals between 30 min and one week. The results were formulated as a reaction sequence describing the interconversions between the distinct silicate species. We generally observed a depletion of Ca2+ ions at the MBG surface, and a minor condensation of the silicate-surface network over one week of SBF soaking. PMID:22349247

Specific patterns of spinal metabolites underlying α-Me-5-HT-evoked pruritus compared with histamine and capsaicin assessed by proton nuclear magnetic resonance spectroscopy.

PubMed

Liu, Taotao; He, Zhigang; Tian, Xuebi; Kamal, Ghulam Mustafa; Li, Zhixiao; Liu, Zeyuan; Liu, Huili; Xu, Fuqiang; Wang, Jie; Xiang, Hongbing

2017-06-01

The mechanism behind itching is not well understood. Proton nuclear magnetic resonance ( 1 H-NMR) spectroscopic analysis of spinal cord extracts provides a quick modality for evaluating the specific metabolic activity of α-Me-5-HT-evoked pruritus mice. In the current study, four groups of young adult male C57Bl/6 mice were investigated; one group treated with saline, while the other groups intradermally injected with α-Me-5-HT (histamine independent pruritogen), histamine (histamine dependent pruritogen) and capsaicin (algogenic substance), respectively. The intradermal microinjection of α-Me-5-HT and histamine resulted in a dramatic increase in the itch behavior. Furthermore, the results of NMR studies of the spinal cord extracts revealed that the metabolites show very different patterns for these different drugs, especially when comparing α-Me-5-HT and capsaicin. All the animals in the groups of α-Me-5-HT and capsaicin were completely separated using the metabolite parameters and principal component analysis. For α-Me-5-HT, the concentrations of glutamate, GABA, glycine and aspartate increased significantly, especially for GABA (increased 17.2%, p=0.008). Furthermore, the concentration of NAA increased, but there was no significant difference (increased 11.3%, p=0.191) compared to capsaicin (decreased 29.1%, p=0.002). Thus the application of magnetic resonance spectroscopy technique, coupled with statistical analysis, could further explain the mechanism behind itching evoked by α-Me-5-HT or other drugs. It can thus improve our understanding of itch pathophysiology and pharmacological therapies which may contribute to itch relief. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of order-disorder transitions in the quest for molecular multiferroics: structural and magnetic neutron studies of a mixed valence iron(II)-iron(III) formate framework.

PubMed

Cañadillas-Delgado, Laura; Fabelo, Oscar; Rodríguez-Velamazán, J Alberto; Lemée-Cailleau, Marie-Hélène; Mason, Sax A; Pardo, Emilio; Lloret, Francesc; Zhao, Jiong-Peng; Bu, Xian-He; Simonet, Virginie; Colin, Claire V; Rodríguez-Carvajal, Juan

2012-12-05

Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH(2)(CH(3))(2)](n)[Fe(III)Fe(II)(HCOO)(6)](n). The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities of the [Fe(III)Fe(II)(HCOO)(6)](n) framework. In the low-temperature phase, a change in space group from P31c to R3c occurs, involving a tripling of the c-axis due to the ordering of the dimethylammonium counterion. The occurrence of this nuclear phase transition is associated with an electric transition, from paraelectric to antiferroelectric. A combination of powder and single crystal neutron diffraction measurements below the magnetic order transition (ca. 37 K) has been used to determine unequivocally the magnetic structure of this Néel N-Type ferrimagnet, proving that the ferrimagnetic behavior is due to a noncompensation of the different Fe(II) and Fe(III) magnetic moments.

Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

NASA Astrophysics Data System (ADS)

Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

2015-11-01

Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urban, Jeffry Todd

Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantum-mechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics.more » The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nuclei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy. The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.« less

A simple scheme for magnetic balance in four-component relativistic Kohn-Sham calculations of nuclear magnetic resonance shielding constants in a Gaussian basis.

PubMed

Olejniczak, Małgorzata; Bast, Radovan; Saue, Trond; Pecul, Magdalena

2012-01-07

We report the implementation of nuclear magnetic resonance (NMR) shielding tensors within the four-component relativistic Kohn-Sham density functional theory including non-collinear spin magnetization and employing London atomic orbitals to ensure gauge origin independent results, together with a new and efficient scheme for assuring correct balance between the large and small components of a molecular four-component spinor in the presence of an external magnetic field (simple magnetic balance). To test our formalism we have carried out calculations of NMR shielding tensors for the HX series (X = F, Cl, Br, I, At), the Xe atom, and the Xe dimer. The advantage of simple magnetic balance scheme combined with the use of London atomic orbitals is the fast convergence of results (when compared with restricted kinetic balance) and elimination of linear dependencies in the basis set (when compared to unrestricted kinetic balance). The effect of including spin magnetization in the description of NMR shielding tensor has been found important for hydrogen atoms in heavy HX molecules, causing an increase of isotropic values of 10%, but negligible for heavy atoms.

PROGRESS IN DESIGN OF THE INSTRUMENTATION AND CONTROL OF THE TOKAMAK COOLING WATER SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korsah, Kofi; DeVan, Bill; Ashburn, David

This paper discusses progress in the design of the control, interlock and safety systems of the Tokamak Cooling Water System (TCWS) for the ITER fusion reactor. The TCWS instrumentation and control (I&C) is one of approximately 200 separate plant I&C systems (e.g., vacuum system I&C, magnets system I&C) that interface to a common central I&C system through standardized networks. Several aspects of the I&C are similar to the I&C of fission-based power plants. However, some of the unique features of the ITER fusion reactor and the TCWS (e.g., high quasi-static magnetic field, need for baking and drying as well asmore » cooling operations), also demand some unique safety and qualification considerations. The paper compares the design strategy/guidelines of the TCWS I&C and the I&C of conventional nuclear power plants. Issues such as safety classifications, independence between control and safety systems, sensor sharing, redundancy, voting schemes, and qualification methodologies are discussed. It is concluded that independence and separation requirements are similar in both designs. However, the voting schemes for safety systems in nuclear power plants typically use 2oo4 (i.e., 4 divisions of safety I&C, any 2 of which is sufficient to trigger a safety action), while 2oo3 voting logic - within each of 2 independent trains - is used in the TCWS I&C. It is also noted that 2oo3 voting is also acceptable in nuclear power plants if adequate risk assessment and reliability is demonstrated. Finally, while qualification requirements provide similar guidance [e.g., both IEC 60780 (invoked in ITER-space), and IEEE 323 (invoked in fission power plant space) provide similar guidance], an important qualification consideration is the susceptibility of I&C to the magnetic fields of ITER. Also, the radiation environments are different. In the case of magnetic fields the paper discusses some options that are being considered.« less

Current and Perspective Applications of Dense Plasma Focus Devices

NASA Astrophysics Data System (ADS)

Gribkov, V. A.

2008-04-01

Dense Plasma Focus (DPF) devices' applications, which are intended to support the main-stream large-scale nuclear fusion programs (NFP) from one side (both in fundamental problems of Dense Magnetized Plasma physics and in its engineering issues) as well as elaborated for an immediate use in a number of fields from the other one, are described. In the first direction such problems as self-generated magnetic fields, implosion stability of plasma shells having a high aspect ratio, etc. are important for the Inertial Confinement Fusion (ICF) programs (e.g. as NIF), whereas different problems of current disruption phenomenon, plasma turbulence, mechanisms of generation of fast particles and neutrons in magnetized plasmas are of great interest for the large devices of the Magnetic Plasma Confinement—MPC (e.g. as ITER). In a sphere of the engineering problems of NFP it is shown that in particular the radiation material sciences have DPF as a very efficient tool for radiation tests of prospect materials and for improvement of their characteristics. In the field of broad-band current applications some results obtained in the fields of radiation material sciences, radiobiology, nuclear medicine, express Neutron Activation Analysis (including a single-shot interrogation of hidden illegal objects), dynamic non-destructive quality control, X-Ray microlithography and micromachining, and micro-radiography are presented. As the examples of the potential future applications it is proposed to use DPF as a powerful high-flux neutron source to generate very powerful pulses of neutrons in the nanosecond (ns) range of its duration for innovative experiments in nuclear physics, for the goals of radiation treatment of malignant tumors, for neutron tests of materials of the first wall, blankets and NFP device's constructions (with fluences up to 1 dpa per a year term), and ns pulses of fast electrons, neutrons and hard X-Rays for brachytherapy.

Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris

2015-02-24

This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR)more » and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements were collected on columns of Rifle sediments during acetate amendment. The laboratory experiments were designed to simulate the field experiments; changes in geophysical signals were expected to correlate with changes in redox conditions and iron speciation. Field MS logging measurements revealed vertically stratified magnetic mineralization, likely the result of detrital magnetic fraction within the bulk alluvium. Little to no change was observed in the MS data suggesting negligible production of magnetic phases (e.g. magnetite, pyrrhotite) as a result of sulfidogenesis. Borehole NMR measurements contained high levels of noise contamination requiring significant signal processing, and analysis suggests that any changes may be difficult to differentiate from simultaneous changes in water content. Laboratory MS and NMR measurements remained relatively stable throughout the course of the acetate amendment experiment, consistent with field measurements. However, SIP measurements changed during the acetate amendment associated with the formation of iron-sulfide mineral phases; a finding that is consistent with chemical analysis of the solid phase materials in the columns.« less

Mechanisms of superconductivity investigated by nuclear radiation

NASA Technical Reports Server (NTRS)

Autler, S. H.; Coffey, H. T.; Keller, E. L.; Patterson, A.

1967-01-01

Investigation focused on the behavior of superconducting magnet and its constituent materials during and after exposure to nuclear radiation. The results will indicate the feasibility of their use in diverse applications and various environments.

A quasi-optical and corrugated waveguide microwave transmission system for simultaneous dynamic nuclear polarization NMR on two separate 14.1 T spectrometers

PubMed Central

Dubroca, Thierry; Smith, Adam N.; Pike, Kevin J.; Froud, Stuart; Wylde, Richard; Trociewitz, Bianca; McKay, Johannes; Mentink-Vigier, Frederic; van Tol, Johan; Wi, Sungsool; Brey, William; Long, Joanna R.; Frydman, Lucio; Hill, Stephen

2018-01-01

Nuclear magnetic resonance (NMR) is an intrinsically insensitive technique, with Boltzmann distributions of nuclear spin states on the order of parts per million in conventional magnetic fields. To overcome this limitation, dynamic nuclear polarization (DNP) can be used to gain up to three orders of magnitude in signal enhancement, which can decrease experimental time by up to six orders of magnitude. In DNP experiments, nuclear spin polarization is enhanced by transferring the relatively larger electron polarization to NMR active nuclei via microwave irradiation. Here, we describe the design and performance of a quasi-optical system enabling the use of a single 395 GHz gyrotron microwave source to simultaneously perform DNP experiments on two different 14.1 T (1H 600 MHz) NMR spectrometers: one configured for magic angle spinning (MAS) solid state NMR; the other configured for solution state NMR experiments. In particular, we describe how the high power microwave beam is split, transmitted, and manipulated between the two spectrometers. A 13C enhancement of 128 is achieved via the cross effect for alanine, using the nitroxide biradical AMUPol, under MAS-DNP conditions at 110 K, while a 31P enhancement of 160 is achieved via the Overhauser effect for triphenylphosphine using the monoradical BDPA under solution NMR conditions at room temperature. The latter result is the first demonstration of Overhauser DNP in the solution state at a field of 14.1 T (1H 600 MHz). Moreover these results have been produced with large sample volumes (~100 μL, i.e. 3 mm diameter NMR tubes). PMID:29459343

A quasi-optical and corrugated waveguide microwave transmission system for simultaneous dynamic nuclear polarization NMR on two separate 14.1 T spectrometers

NASA Astrophysics Data System (ADS)

Dubroca, Thierry; Smith, Adam N.; Pike, Kevin J.; Froud, Stuart; Wylde, Richard; Trociewitz, Bianca; McKay, Johannes; Mentink-Vigier, Frederic; van Tol, Johan; Wi, Sungsool; Brey, William; Long, Joanna R.; Frydman, Lucio; Hill, Stephen

2018-04-01

Nuclear magnetic resonance (NMR) is an intrinsically insensitive technique, with Boltzmann distributions of nuclear spin states on the order of parts per million in conventional magnetic fields. To overcome this limitation, dynamic nuclear polarization (DNP) can be used to gain up to three orders of magnitude in signal enhancement, which can decrease experimental time by up to six orders of magnitude. In DNP experiments, nuclear spin polarization is enhanced by transferring the relatively larger electron polarization to NMR active nuclei via microwave irradiation. Here, we describe the design and performance of a quasi-optical system enabling the use of a single 395 GHz gyrotron microwave source to simultaneously perform DNP experiments on two different 14.1 T (1H 600 MHz) NMR spectrometers: one configured for magic angle spinning (MAS) solid state NMR; the other configured for solution state NMR experiments. In particular, we describe how the high power microwave beam is split, transmitted, and manipulated between the two spectrometers. A 13C enhancement of 128 is achieved via the cross effect for alanine, using the nitroxide biradical AMUPol, under MAS-DNP conditions at 110 K, while a 31P enhancement of 160 is achieved via the Overhauser effect for triphenylphosphine using the monoradical BDPA under solution NMR conditions at room temperature. The latter result is the first demonstration of Overhauser DNP in the solution state at a field of 14.1 T (1H 600 MHz). Moreover these results have been produced with large sample volumes (∼100 μL, i.e. 3 mm diameter NMR tubes).

A quasi-optical and corrugated waveguide microwave transmission system for simultaneous dynamic nuclear polarization NMR on two separate 14.1 T spectrometers.

PubMed

Dubroca, Thierry; Smith, Adam N; Pike, Kevin J; Froud, Stuart; Wylde, Richard; Trociewitz, Bianca; McKay, Johannes; Mentink-Vigier, Frederic; van Tol, Johan; Wi, Sungsool; Brey, William; Long, Joanna R; Frydman, Lucio; Hill, Stephen

2018-04-01

Nuclear magnetic resonance (NMR) is an intrinsically insensitive technique, with Boltzmann distributions of nuclear spin states on the order of parts per million in conventional magnetic fields. To overcome this limitation, dynamic nuclear polarization (DNP) can be used to gain up to three orders of magnitude in signal enhancement, which can decrease experimental time by up to six orders of magnitude. In DNP experiments, nuclear spin polarization is enhanced by transferring the relatively larger electron polarization to NMR active nuclei via microwave irradiation. Here, we describe the design and performance of a quasi-optical system enabling the use of a single 395 GHz gyrotron microwave source to simultaneously perform DNP experiments on two different 14.1 T ( 1 H 600 MHz) NMR spectrometers: one configured for magic angle spinning (MAS) solid state NMR; the other configured for solution state NMR experiments. In particular, we describe how the high power microwave beam is split, transmitted, and manipulated between the two spectrometers. A 13 C enhancement of 128 is achieved via the cross effect for alanine, using the nitroxide biradical AMUPol, under MAS-DNP conditions at 110 K, while a 31 P enhancement of 160 is achieved via the Overhauser effect for triphenylphosphine using the monoradical BDPA under solution NMR conditions at room temperature. The latter result is the first demonstration of Overhauser DNP in the solution state at a field of 14.1 T ( 1 H 600 MHz). Moreover these results have been produced with large sample volumes (∼100 µL, i.e. 3 mm diameter NMR tubes). Copyright © 2018 Elsevier Inc. All rights reserved.

Design and test of a double-nuclear RF coil for 1H MRI and 13C MRSI at 7 T

NASA Astrophysics Data System (ADS)

Rutledge, Omar; Kwak, Tiffany; Cao, Peng; Zhang, Xiaoliang

2016-06-01

RF coil operation at the ultrahigh field of 7 T is fraught with technical challenges that limit the advancement of novel human in vivo applications at 7 T. In this work, a hybrid technique combining a microstrip transmission line and a lumped-element L-C loop coil to form a double-nuclear RF coil for proton magnetic resonance imaging and carbon magnetic resonance spectroscopy at 7 T was proposed and investigated. Network analysis revealed a high Q-factor and excellent decoupling between the coils. Proton images and localized carbon spectra were acquired with high sensitivity. The successful testing of this novel double-nuclear coil demonstrates the feasibility of this hybrid design for double-nuclear MR imaging and spectroscopy studies at the ultrahigh field of 7 T.

Astrophysical Nuclear Reaction Rates in the Dense Metallic Environments

NASA Astrophysics Data System (ADS)

Kilic, Ali Ihsan

2017-09-01

Nuclear reaction rates can be enhanced by many orders of magnitude in dense and relatively cold astrophysical plasmas such as in white dwarfs, brown dwarfs, and giant planets. Similar conditions are also present in supernova explosions where the ignition conditions are vital for cosmological models. White dwarfs are compact objects that have both extremely high interior densities and very strong local magnetic fields. For the first time, a new formula has been developed to explain cross section and reaction rate quantities for light elements that includes not only the nuclear component but also the material dependence, magnetic field, and crystal structure dependency in dense metallic environments. I will present the impact of the developed formula on the cross section and reaction rates for light elements. This could have possible technological applications in energy production using nuclear fusion reactions.

Fully gapped spin-singlet superconductivity in noncentrosymmetric PbTaSe2: 207Pb nuclear magnetic resonance study

NASA Astrophysics Data System (ADS)

Maeda, S.; Matano, K.; Zheng, Guo-qing

2018-05-01

We report the 207Pb nuclear magnetic resonance (NMR) measurements on polycrystalline sample of PbTaSe2 with noncentrosymmetric crystal structure and topological electronic band. The nuclear spin-lattice relaxation rate 1 /T1 shows a suppressed coherence peak below the superconducting transition temperature Tc=4.05 K and decreases as an exponential function of temperature. The penetration depth derived from the NMR spectrum is almost temperature independent below T =0.7 Tc. The Knight shift K decreases below Tc. These results suggest spin-singlet superconductivity with a fully opened gap 2 Δ =3.5 kBTc in PbTaSe2.

Electrical detection of ortho–para conversion in fullerene-encapsulated water

PubMed Central

Meier, Benno; Mamone, Salvatore; Concistrè, Maria; Alonso-Valdesueiro, Javier; Krachmalnicoff, Andrea; Whitby, Richard J.; Levitt, Malcolm H.

2015-01-01

Water exists in two spin isomers, ortho and para, that have different nuclear spin states. In bulk water, rapid proton exchange and hindered molecular rotation obscure the direct observation of two spin isomers. The supramolecular endofullerene H2O@C60 provides freely rotating, isolated water molecules even at cryogenic temperatures. Here we show that the bulk dielectric constant of this substance depends on the ortho/para ratio, and changes slowly in time after a sudden temperature jump, due to nuclear spin conversion. The attribution of the effect to ortho–para conversion is validated by comparison with nuclear magnetic resonance and quantum theory. The change in dielectric constant is consistent with an electric dipole moment of 0.51±0.05 Debye for an encapsulated water molecule, indicating the partial shielding of the water dipole by the encapsulating cage. The dependence of bulk dielectric constant on nuclear spin isomer composition appears to be a previously unreported physical phenomenon. PMID:26299447

Origin of the magnetoelectric effect in the Cs2FeCl5.D2O compound

NASA Astrophysics Data System (ADS)

Fabelo, Oscar; Rodríguez-Velamazán, J. Alberto; Canadillas-Delgado, Laura; Mazzuca, Lidia; Campo, Javier; Millán, Ángel; Chapon, Laurent C.; Rodríguez-Carvajal, Juan

2017-09-01

Cs2FeCl5.D2O has been identified as a linear magnetoelectric material, although the correlation of this property with the magnetic structures of this compound has not been adequately studied. We have used single-crystal and powder neutron diffraction to obtain detailed information about its nuclear and magnetic structures. From the nuclear structure analysis, we describe the occurrence of a phase transition related to the reorganization of the [FeCl5.D2O] -2 ions and the Cs+ counterion. The magnetic structure was determined at zero magnetic field at 1.8 K using single-crystal diffraction and its temperature evolution was recorded using powder diffraction. The symmetry analysis of the magnetic structure is compatible with the occurrence of the magnetoelectric effect. Moreover, the evolution of the magnetic structure as a function of the external magnetic field has also been studied. The reorientation of the magnetic moments under applied external field along the easy axis (b axis at low temperature) is compatible with the occurrence of a spin-flop transition. The application of a magnetic field below TN compels the magnetic moments to flip from the b axis to the a c plane (with a small induced component along the b axis), for a critical magnetic field of ca. 1.2 T.

Investigating a Quadrant Surface Coil Array for NQR Remote Sensing

DTIC Science & Technology

2014-10-23

UNCLASSIFIED 1  Abstract—this paper is on the design and fabrication of a surface coil array in a quadrant layout for NQR (Nuclear Quadrupole...coupling and SNR (Signal-to-Noise Ratio) at standoff distances perpendicular from each coil. Index Terms— Nuclear Quadrupole Resonance, NQR ...Coil Array, probe, Nuclear Magnetic Resonance, tuning, decoupling, RLC, mutual coupling, RLC I. INTRODUCTION N Nuclear quadrupole resonance ( NQR

Nuclear relaxation in an electric field enables the determination of isotropic magnetic shielding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garbacz, Piotr, E-mail: pgarbacz@chem.uw.edu.pl

2016-08-14

It is shown that in contrast to the case of nuclear relaxation in a magnetic field B, simultaneous application of the magnetic field B and an additional electric field E causes transverse relaxation of a spin-1/2 nucleus with the rate proportional to the square of the isotropic part of the magnetic shielding tensor. This effect can contribute noticeably to the transverse relaxation rate of heavy nuclei in molecules that possess permanent electric dipole moments. Relativistic quantum mechanical computations indicate that for {sup 205}Tl nucleus in a Pt-Tl bonded complex, Pt(CN){sub 5}Tl, the transverse relaxation rate induced by the electric fieldmore » is of the order of 1 s{sup −1} at E = 5 kV/mm and B = 10 T.« less

Moissanite anvil cell design for Giga-Pascal nuclear magnetic resonance.

PubMed

Meier, Thomas; Herzig, Tobias; Haase, Jürgen

2014-04-01

A new design of a non-magnetic high-pressure anvil cell for nuclear magnetic resonance (NMR) experiments at Giga-Pascal pressures is presented, which uses a micro-coil inside the pressurized region for high-sensitivity NMR. The comparably small cell has a length of 22 mm and a diameter of 18 mm, so it can be used with most NMR magnets. The performance of the cell is demonstrated with external-force vs. internal-pressure experiments, and the cell is shown to perform well at pressures up to 23.5 GPa using 800 μm 6H-SiC large cone Boehler-type anvils. (1)H, (23)Na, (27)Al, (69)Ga, and (71)Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.

Time-domain multiple-quantum NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weitekamp, Daniel P.

1982-11-01

The development of time-domain multiple-quantum nuclear magnetic resonance is reviewed through mid 1982 and some prospects for future development are indicated. Particular attention is given to the problem of obtaining resolved, interpretable, many-quantum spectra for anisotropic magnetically isolated systems of coupled spins. New results are presented on a number of topics including the optimization of multiple-quantum-line intensities, analysis of noise in two-dimensional spectroscopy, and the use of order-selective excitation for cross polarization between nuclear-spin species.

Computer Code for Interpreting 13C NMR Relaxation Measurements with Specific Models of Molecular Motion: The Rigid Isotropic and Symmetric Top Rotor Models and the Flexible Symmetric Top Rotor Model

DTIC Science & Technology

2017-01-01

unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT: Carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy is a powerful technique for...FLEXIBLE SYMMETRIC TOP ROTOR MODEL 1. INTRODUCTION Nuclear magnetic resonance (NMR) spectroscopy is a tremendously powerful technique for...application of NMR spectroscopy concerns the property of molecular motion, which is related to many physical, and even biological, functions of molecules in

The application of NMR and MS methods for detection of adulteration of wine, fruit juices, and olive oil. A review.

PubMed

Ogrinc, N; Kosir, I J; Spangenberg, J E; Kidric, J

2003-06-01

This review covers two important techniques, high resolution nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), used to characterize food products and detect possible adulteration of wine, fruit juices, and olive oil, all important products of the Mediterranean Basin. Emphasis is placed on the complementary use of SNIF-NMR (site-specific natural isotopic fractionation nuclear magnetic resonance) and IRMS (isotope-ratio mass spectrometry) in association with chemometric methods for detecting the adulteration.

Solid state nuclear magnetic resonance studies of prion peptides and proteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heller, Jonathan

1997-08-01

High-resolution structural studies using x-ray diffraction and solution nuclear magnetic resonance (NMR) are not feasible for proteins of low volubility and high tendency to aggregate. Solid state NMR (SSNMR) is in principle capable of providing structural information in such systems, however to do this efficiently and accurately, further SSNMR tools must be developed This dissertation describes the development of three new methods and their application to a biological system of interest, the priori protein (PrP).

A noninvasive method to study regulation of extracellular fluid volume in rats using nuclear magnetic resonance

EPA Pesticide Factsheets

NMR fluid measurements of commonly used rat strains when subjected to SQ normotonic or hypertonic salines, as well as physiologic comparisons to sedentary and exercised subjects.This dataset is associated with the following publication:Gordon , C., P. Phillips , and A. Johnstone. A Noninvasive Method to Study Regulation of Extracellular Fluid Volume in Rats Using Nuclear Magnetic Resonance. American Journal of Physiology- Renal Physiology. American Physiological Society, Bethesda, MD, USA, 310(5): 426-31, (2016).

Diagnostic imaging of the lower genitourinary tract

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rifkin, M.D.

1985-01-01

Dr. Rifkin analyzes the relative merits of ultrasound, computed tomography, magnetic resonance imaging, nuclear medicine, and radiography. He correlates ultrasound findings with those of computed tomography, radiography, and nuclear medicine and assesses the potential benefits of magnetic resonance imaging as compared with ultrasound and other imaging modalities. Each imaging modality is discussed in terms of its role as the primary, secondary, or complementary study for diagnoses involving the urinary bladder and perivesical spaces, the prostate and seminal vesicles, the urethra and penis, and the scrotal sac.

Double-spiral magnetic structure of the Fe/Cr multilayer revealed by nuclear resonance reflectivity

NASA Astrophysics Data System (ADS)

Andreeva, M. A.; Baulin, R. A.; Chumakov, A. I.; Rüffer, R.; Smirnov, G. V.; Babanov, Y. A.; Devyaterikov, D. I.; Milyaev, M. A.; Ponomarev, D. A.; Romashev, L. N.; Ustinov, V. V.

2018-01-01

We have studied the magnetization depth profiles in a [57Fe (dFe) /Cr (dCr) ]30 multilayer with ultrathin Fe layers and nominal thickness of the chromium spacers dCr≈2.0 nm using nuclear resonance scattering of synchrotron radiation. The presence of a broad pure-magnetic half-order (1/2) Bragg reflection has been detected at zero external field. The joint fit of the reflectivity curves and Mössbauer spectra of reflectivity measured near the critical angle and at the "magnetic" peak reveals that the magnetic structure of the multilayer is formed by two spirals, one in the odd and another one in the even iron layers, with the opposite signs of rotation. The double-spiral structure starts from the surface with the almost-antiferromagnetic alignment of the adjacent Fe layers. The rotation of the two spirals leads to nearly ferromagnetic alignment of the two magnetic subsystems at some depth, where the sudden turn of the magnetic vectors by ˜180∘ (spin flop) appears, and both spirals start to rotate in opposite directions. The observation of this unusual double-spiral magnetic structure suggests that the unique properties of giant magnetoresistance devices can be further tailored using ultrathin magnetic layers.

Design and Analysis of Embedded I&C for a Fully Submerged Magnetically Suspended Impeller Pump

DOE PAGES

Melin, Alexander M.; Kisner, Roger A.

2018-04-03

Improving nuclear reactor power system designs and fuel-processing technologies for safer and more efficient operation requires the development of new component designs. In particular, many of the advanced reactor designs such as the molten salt reactors and high-temperature gas-cooled reactors have operating environments beyond the capability of most currently available commercial components. To address this gap, new cross-cutting technologies need to be developed that will enable design, fabrication, and reliable operation of new classes of reactor components. The Advanced Sensor Initiative of the Nuclear Energy Enabling Technologies initiative is investigating advanced sensor and control designs that are capable of operatingmore » in these extreme environments. Under this initiative, Oak Ridge National Laboratory (ORNL) has been developing embedded instrumentation and control (I&C) for extreme environments. To develop, test, and validate these new sensing and control techniques, ORNL is building a pump test bed that utilizes submerged magnetic bearings to levitate the shaft. The eventual goal is to apply these techniques to a high-temperature (700°C) canned rotor pump that utilizes active magnetic bearings to eliminate the need for mechanical bearings and seals. The technologies will benefit the Next Generation Power Plant, Advanced Reactor Concepts, and Small Modular Reactor programs. In this paper, we will detail the design and analysis of the embedded I&C test bed with submerged magnetic bearings, focusing on the interplay between the different major systems. Then we will analyze the forces on the shaft and their role in the magnetic bearing design. Next, we will develop the radial and thrust bearing geometries needed to meet the operational requirements of the test bed. In conclusion, we will present some initial system identification results to validate the theoretical models of the test bed dynamics.« less

Design and Analysis of Embedded I&C for a Fully Submerged Magnetically Suspended Impeller Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melin, Alexander M.; Kisner, Roger A.

Improving nuclear reactor power system designs and fuel-processing technologies for safer and more efficient operation requires the development of new component designs. In particular, many of the advanced reactor designs such as the molten salt reactors and high-temperature gas-cooled reactors have operating environments beyond the capability of most currently available commercial components. To address this gap, new cross-cutting technologies need to be developed that will enable design, fabrication, and reliable operation of new classes of reactor components. The Advanced Sensor Initiative of the Nuclear Energy Enabling Technologies initiative is investigating advanced sensor and control designs that are capable of operatingmore » in these extreme environments. Under this initiative, Oak Ridge National Laboratory (ORNL) has been developing embedded instrumentation and control (I&C) for extreme environments. To develop, test, and validate these new sensing and control techniques, ORNL is building a pump test bed that utilizes submerged magnetic bearings to levitate the shaft. The eventual goal is to apply these techniques to a high-temperature (700°C) canned rotor pump that utilizes active magnetic bearings to eliminate the need for mechanical bearings and seals. The technologies will benefit the Next Generation Power Plant, Advanced Reactor Concepts, and Small Modular Reactor programs. In this paper, we will detail the design and analysis of the embedded I&C test bed with submerged magnetic bearings, focusing on the interplay between the different major systems. Then we will analyze the forces on the shaft and their role in the magnetic bearing design. Next, we will develop the radial and thrust bearing geometries needed to meet the operational requirements of the test bed. In conclusion, we will present some initial system identification results to validate the theoretical models of the test bed dynamics.« less

Notch filtering the nuclear environment of a spin qubit.

PubMed

Malinowski, Filip K; Martins, Frederico; Nissen, Peter D; Barnes, Edwin; Cywiński, Łukasz; Rudner, Mark S; Fallahi, Saeed; Gardner, Geoffrey C; Manfra, Michael J; Marcus, Charles M; Kuemmeth, Ferdinand

2017-01-01

Electron spins in gate-defined quantum dots provide a promising platform for quantum computation. In particular, spin-based quantum computing in gallium arsenide takes advantage of the high quality of semiconducting materials, reliability in fabricating arrays of quantum dots and accurate qubit operations. However, the effective magnetic noise arising from the hyperfine interaction with uncontrolled nuclear spins in the host lattice constitutes a major source of decoherence. Low-frequency nuclear noise, responsible for fast (10 ns) inhomogeneous dephasing, can be removed by echo techniques. High-frequency nuclear noise, recently studied via echo revivals, occurs in narrow-frequency bands related to differences in Larmor precession of the three isotopes 69 Ga, 71 Ga and 75 As (refs 15,16,17). Here, we show that both low- and high-frequency nuclear noise can be filtered by appropriate dynamical decoupling sequences, resulting in a substantial enhancement of spin qubit coherence times. Using nuclear notch filtering, we demonstrate a spin coherence time (T 2 ) of 0.87 ms, five orders of magnitude longer than typical exchange gate times, and exceeding the longest coherence times reported to date in Si/SiGe gate-defined quantum dots.

Non-invasively predicting differentiation of pancreatic cancer through comparative serum metabonomic profiling.

PubMed

Wen, Shi; Zhan, Bohan; Feng, Jianghua; Hu, Weize; Lin, Xianchao; Bai, Jianxi; Huang, Heguang

2017-11-02

The differentiation of pancreatic ductal adenocarcinoma (PDAC) could be associated with prognosis and may influence the choices of clinical management. No applicable methods could reliably predict the tumor differentiation preoperatively. Thus, the aim of this study was to compare the metabonomic profiling of pancreatic ductal adenocarcinoma with different differentiations and assess the feasibility of predicting tumor differentiations through metabonomic strategy based on nuclear magnetic resonance spectroscopy. By implanting pancreatic cancer cell strains Panc-1, Bxpc-3 and SW1990 in nude mice in situ, we successfully established the orthotopic xenograft models of PDAC with different differentiations. The metabonomic profiling of serum from different PDAC was achieved and analyzed by using 1 H nuclear magnetic resonance (NMR) spectroscopy combined with the multivariate statistical analysis. Then, the differential metabolites acquired were used for enrichment analysis of metabolic pathways to get a deep insight. An obvious metabonomic difference was demonstrated between all groups and the pattern recognition models were established successfully. The higher concentrations of amino acids, glycolytic and glutaminolytic participators in SW1990 and choline-contain metabolites in Panc-1 relative to other PDAC cells were demonstrated, which may be served as potential indicators for tumor differentiation. The metabolic pathways and differential metabolites identified in current study may be associated with specific pathways such as serine-glycine-one-carbon and glutaminolytic pathways, which can regulate tumorous proliferation and epigenetic regulation. The NMR-based metabonomic strategy may be served as a non-invasive detection method for predicting tumor differentiation preoperatively.

High-Nuclearity Magnetic Clusters: Generalized Spin Hamiltonian and Its Use for the Calculation of the Energy Levels, Bulk Magnetic Properties, and Inelastic Neutron Scattering Spectra.

PubMed

Borrás-Almenar, J. J.; Clemente-Juan, J. M.; Coronado, E.; Tsukerblat, B. S.

1999-12-27

A general solution of the exchange problem in the high-nuclearity spin clusters (HNSC) containing arbitrary number of exchange-coupled centers and topology is developed. All constituent magnetic centers are supposed to possess well-isolated orbitally non-degenerate ground states so that the isotropic Heisenberg-Dirac-Van Vleck (HDVV) term is the leading part of the exchange spin Hamiltonian. Along with the HDVV term, we consider higher-order isotropic exchange terms (biquadratic exchange), as well as the anisotropic terms (anisotropic and antisymmetric exchange interactions and local single-ion anisotropies). All these terms are expressed as irreducible tensor operators (ITO). This allows us to take full advantage of the spin symmetry of the system. At the same time, we have also benefitted by taking into account the point group symmetry of the cluster, which allows us to work with symmetrized spin functions. This results in an additional reduction of the matrices to diagonalize. The approach developed here is accompanied by an efficient computational procedure that allows us to calculate the bulk magnetic properties (magnetic susceptibility, magnetization, and magnetic specific heat) as well as the spectroscopic properties of HNSC. Special attention is paid to calculate the magnetic excitations observed by inelastic neutron scattering (INS), their intensities, and their Q and temperature dependencies. This spectroscopic technique provides direct access to the energies and wave functions of the different spin states of the cluster; thus, it can be applied to spin clusters in order to obtain deep and detailed information on the nature of the magnetic exchange phenomenon. The general expression for the INS cross-section of spin clusters interacting by all kinds of exchange interactions, including also the single-ion zero-field splitting term, is derived for the first time. A closed-form expression is also derived for the particular case in which only the isotropic exchange interactions are involved. Finally this approach has been used to model the magnetic properties as well as the INS spectra of the polyoxometalate anion [Ni(9)(OH)(3)(H(2)O)(6)(HPO(4))(2)(PW(9)O(34))(3)](16)(-), which contains a central magnetic cluster formed by nine exchange-coupled Ni(II) ions surrounded by diamagnetic phosphotungstate ligands (PW(9)O(34))(9)(-).

Electromagnetic Nature of Nuclear Energy

NASA Astrophysics Data System (ADS)

Schaeffer, Bernard

2014-09-01

As it is known since two millenaries, there is an attraction between an electric charge and a neutral object. Coulomb found the fundamental laws of electricity two centuries ago. After one century of nuclear physics, the fundamental laws of the strong force are still ignored. It has been found that electric and magnetic Coulomb's laws alone, without any hypothetical centrifugal force, are able to predict the binding energy of the simplest bound nucleus, the deuteron 2 H with a precision of 4 % . The nuclear potential is given by the formula: Uem2 H / A =e2/4 πɛ0 (1/rnp + a - 1/rnp - a ) + μ0 |μnμp |/4 π rnp3. This potential shows a horizontal inflection point where the electric and magnetic forces are equilibrated, coinciding with the experimental deuteron binding energy. Similar results have been obtained for the α particle 4 He where the electric attractive potential is four times larger than that of 2 H while the magnetic repulsion is only 1 . 5 times larger and the 4 HE binding energy six times larger than that of the deuteron. These results, prove the electromagnetic nature of the nuclear energy without the usual assumptions.

A study of heavy-heavy nuclear reactions. [nuclear research/nuclear particles

NASA Technical Reports Server (NTRS)

Khandelwal, G. S.

1975-01-01

Calculations are presented for the reaction products in high energy collisions and of the atmospheric transport of particles such as protons, neutrons and other nucleons. The magnetic moments of charmed baryons are examined. Total cross sections which are required for cosmic heavy ion transport and shielding studies are also examined.

ONR Far East Scientific Bulletin, Volume 7, Number 4, October-December 1982,

DTIC Science & Technology

1982-12-01

transition metal compounds (2), - ESR and relaxation (3), - rare earth and actinides (3), - magnetics and superconductivity (3), - transition metal...34Itinerant Electron Magnetism ," by T. Moriya, - "Organic Superconductivity ," by D. Jerome, and - "Recent Developments in Solid Earth Sciences," by...compounds, low dimension systems, random systems, surface magnetism , magnetism and superconductivity , Kondo problem, diamagnetism and nuclear

Investigation of laser polarized xenon magnetic resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

1998-01-01

Ground-based investigations of a new biomedical diagnostic technology: nuclear magnetic resonance of laser polarized noble gas are addressed. The specific research tasks discussed are: (1) Development of a large-scale noble gas polarization system; (2) biomedical investigations using laser polarized noble gas in conventional (high magnetic field) NMR systems; and (3) the development and application of a low magnetic field system for laser polarized noble gas NMR.

NMR study of heavy fermion compound EuNi2P2

NASA Astrophysics Data System (ADS)

Magishi, K.; Watanabe, R.; Hisada, A.; Saito, T.; Koyama, K.; Fujiwara, T.

2015-03-01

We report the results of 31P-nuclear magnetic resonance (NMR) measurements on heavy fermion compound EuNi2P2 in order to investigate the magnetic properties at low temperatures from a microscopic view point. The Knight shift has a negative value in an entire temperature range, and the absolute value increases with decreasing temperature but exhibits a broad maximum around 40 K, which is similar to the behavior of the magnetic susceptibility. Also, the nuclear spin-lattice relaxation rate 1/T1 is almost constant at high temperatures above 200 K, which is reminiscent of the relaxation mechanism dominated by the interaction of the 31P nucleus with fluctuating Eu-4f moments. Below 200 K, 1/T1 gradually decreases on cooling due to the change of the valence in the Eu ion. At low temperatures, 1/T1 does not obey the Korringa relation, in contrast to typical heavy fermion compounds. The nuclear spin-spin relaxation rate 1/T2 shows the similar behavior as 1/T1 at high temperatures. But, below 50 K, 1/T2 increases upon cooling due to the development of the magnetic excitation.

High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Tingting; Zhao, Jing, E-mail: zhaojing-8239@jlu.edu.cn; Peter Grünberg Institute

2014-11-15

In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2more » fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.« less

MHD Effect on Unsteady Mixed Convection Boundary Layer Flow past a Circular Cylinder with Constant Wall Temperature

NASA Astrophysics Data System (ADS)

Ismail, M. A.; Mohamad, N. F.; Ilias, M. R.; Shafie, S.

2017-09-01

Magnetohydrodynamic (MHD) effect is a study on motion of electrical-conducting fluid under magnetic fields. This effect has great intention due to its applications such as design of heat exchanger and nuclear reactor. In the problem in fluid motion, flow of separation can reduced the effectiveness of the system as well as can increased the energy lost. This study will present the results on reducing the flow separation by considering magnetic effect. In this study, unsteady mixed convection boundary layer flow past a circular cylinder is given attention. Focus of study is on the separation times that affected by the magnetic fields. The mathematical models in the form of partial differential equations are transformed into nonlinear coupled ordinary differential equations and solved numerically using an implicit finite-difference scheme known as Keller-box method. The effect of magnetic parameter on velocity and temperature profiles as well as skin friction and Nusselt number are studied.

Medical Imaging.

ERIC Educational Resources Information Center

Jaffe, C. Carl

1982-01-01

Describes principle imaging techniques, their applications, and their limitations in terms of diagnostic capability and possible adverse biological effects. Techniques include film radiography, computed tomography, nuclear medicine, positron emission tomography (PET), ultrasonography, nuclear magnetic resonance, and digital radiography. PET has…

Isotope-Identifying neutron reflectometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikitenko, Yu. V., E-mail: nikiten@nf.jinr.ru; Petrenko, A. V.; Gundorin, N. A.

2015-07-15

The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

Thermal Analysis of Acetylene Terminated Sulfone (ATS) Resin

DTIC Science & Technology

1990-01-18

Hydrogen Sulfide by Difference Gravimetry 71 (6) Analysis by Quantitative Proton Nuclear 72 Magnetic Resonance (NMR) Spectroscopy C.YI The Noncondensable...CARBONYL SULFIDE 24 DISTRIBUTION OF SULFUR IN THE PRODUCTS OF THERMAL 72 DEGRADATION TO 1020’C OF PRECURED ATS-G 25 GRAVIMETRY OF THE CONDENSABLE VOLATILE...procedure was devised making use of gravimetry in conjunction with proton NMR spectroscopy. The condensable volatile product fraction of degradation was

129Xe NMR chemical shift in Xe@C60 calculated at experimental conditions: essential role of the relativity, dynamics, and explicit solvent.

PubMed

Standara, Stanislav; Kulhánek, Petr; Marek, Radek; Straka, Michal

2013-08-15

The isotropic (129)Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the (129)Xe NMR CS. The (129)Xe shielding constant was obtained by averaging the (129)Xe nuclear magnetic shieldings calculated for snapshots obtained from the molecular dynamics trajectory of the Xe@C60 system embedded in a periodic box of benzene molecules. Relativistic corrections were added at the Breit-Pauli perturbation theory (BPPT) level, included the solvent, and were dynamically averaged. It is demonstrated that the contribution of internal dynamics of the Xe@C60 system represents about 8% of the total nonrelativistic NMR CS, whereas the effects of dynamical solvent add another 8%. The dynamically averaged relativistic effects contribute by 9% to the total calculated (129)Xe NMR CS. The final theoretical value of 172.7 ppm corresponds well to the experimental (129)Xe CS of 179.2 ppm and lies within the estimated errors of the model. The presented computational protocol serves as a prototype for calculations of (129)Xe NMR parameters in different Xe atom guest-host systems. Copyright © 2013 Wiley Periodicals, Inc.

Electrically tunable dynamic nuclear spin polarization in GaAs quantum dots at zero magnetic field

NASA Astrophysics Data System (ADS)

Manca, M.; Wang, G.; Kuroda, T.; Shree, S.; Balocchi, A.; Renucci, P.; Marie, X.; Durnev, M. V.; Glazov, M. M.; Sakoda, K.; Mano, T.; Amand, T.; Urbaszek, B.

2018-04-01

In III-V semiconductor nano-structures, the electron and nuclear spin dynamics are strongly coupled. Both spin systems can be controlled optically. The nuclear spin dynamics are widely studied, but little is known about the initialization mechanisms. Here, we investigate optical pumping of carrier and nuclear spins in charge tunable GaAs dots grown on 111A substrates. We demonstrate dynamic nuclear polarization (DNP) at zero magnetic field in a single quantum dot for the positively charged exciton X+ state transition. We tune the DNP in both amplitude and sign by variation of an applied bias voltage Vg. Variation of ΔVg on the order of 100 mV changes the Overhauser splitting (nuclear spin polarization) from -30 μeV (-22%) to +10 μeV (+7%) although the X+ photoluminescence polarization does not change sign over this voltage range. This indicates that absorption in the structure and energy relaxation towards the X+ ground state might provide favourable scenarios for efficient electron-nuclear spin flip-flops, generating DNP during the first tens of ps of the X+ lifetime which is on the order of hundreds of ps. Voltage control of DNP is further confirmed in Hanle experiments.

Compressed baryonic matter at FAIR: JINR participation

NASA Astrophysics Data System (ADS)

Kurilkin, P.; Ladygin, V.; Malakhov, A.; Senger, P.

2015-11-01

The scientific mission of the Compressed Baryonic Matter(CBM) experiment is the study of the nuclear matter properties at the high baryon densities in heavy ion collisions at the Facility of Antiproton and Ion Research (FAIR) in Darmstadt. We present the results on JINR participation in the CBM experiment. JINR teams are responsible on the design, the coordination of superconducting(SC) magnet manufacture, its testing and installation in CBM cave. Together with Silicon Tracker System it will provide the momentum resolution better 1% for different configuration of CBM setup. The characteristics and technical aspects of the magnet are discussed. JINR plays also a significant role in the manufacture of two straw tracker station for the muon detection system. JINR team takes part in the development of new method for simulation, processing and analysis experimental data for different basic detectors of CBM.

The Nobel Prize in Medicine for Magnetic Resonance Imaging

ERIC Educational Resources Information Center

Fry, Charles G.

2004-01-01

Nobel Prize in Medicine awarded in December 2003 to chemist Paul C. Lauterbur and physicist Peter Mansfield for the development of magnetic resonance imaging (MRI), a long overdue recognition of the huge impact MRI has had in medical diagnostics and research is mentioned. MRI was derived, and remains an extension of nuclear magnetic resonance…

Molecular dynamic heterogeneity of confined lipid films by 1H magnetization-exchange nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Buda, A.; Demco, D. E.; Jagadeesh, B.; Blümich, B.

2005-01-01

The molecular dynamic heterogeneity of monolayer to submonolayer thin lecithin films confined to submicron cylindrical pores were investigated by 1H magnetization exchange nuclear magnetic resonance. In this experiment a z-magnetization gradient was generated by a double-quantum dipolar filter. The magnetization-exchange decay and buildup curves were interpreted with the help of a theoretical model based on the approximation of a one-dimensional spin-diffusion process in a three-domain morphology. The dynamic heterogeneity of the fatty acid chains and the effects of the surface area per molecule, the diameter of the pores, and the temperature were characterized with the help of local spin-diffusion coefficients. The effect of various parameters on the molecular dynamics of the mobile region of the fatty acid chains was quantified by introducing an ad hoc Gaussian distribution function of the 1H residual dipolar couplings. For the lipid films investigated in this study, the surface induced order and the geometrical confinement affect the chain dynamics of the entire molecule. Therefore, each part of the chain independently reflects the effect of surface coverage, pore size, and temperature.

Wide-angle x-ray scattering and solid-state nuclear magnetic resonance data combined to test models for cellulose microfibrils in mung bean cell walls.

PubMed

Newman, Roger H; Hill, Stefan J; Harris, Philip J

2013-12-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette.

Status of the measurement of the nuclear components in cosmic rays with the AMS-02 experiment

NASA Astrophysics Data System (ADS)

Donnini, F.

2017-01-01

The Alpha Magnetic Spectrometer (AMS-02) is a large-acceptance (0.45 m 2 sr) magnetic spectrometer operating on board the International Space Station since May 2011. One of the main scientific objectives of the mission is the measurement of the nuclei fluxes in cosmic rays (CR). The identification of nuclei is achieved by the combination of independent measurements of the absolute charge, provided by different sub-detectors: the Silicon Tracker, the Time-of-Flight system (TOF), the Ring Imaging Cherenkov Counter (RICH), the Transition Radiation Detector (TRD) and the Electromagnetic Calorimeter (ECAL). In this contribution the results of nuclei fluxes already shown by the AMS collaboration are presented.

Combining Two-Dimensional Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy, Imaging Desorption Electrospray Ionization Mass Spectrometry, and Direct Analysis in Real-Time Mass Spectrometry for the Integral Investigation of Counterfeit Pharmaceuticals

PubMed Central

Nyadong, Leonard; Harris, Glenn A.; Balayssac, Stéphane; Galhena, Asiri S.; Malet-Martino, Myriam; Martino, Robert; Parry, R. Mitchell; Wang, May Dongmei; Fernández, Facundo M.; Gilard, Véronique

2016-01-01

During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered 1H nuclear magnetic resonance spectroscopy (2D DOSY 1H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY 1H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug “chemotyping”. In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY 1H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials. PMID:19453162

Combining two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy, imaging desorption electrospray ionization mass spectrometry, and direct analysis in real-time mass spectrometry for the integral investigation of counterfeit pharmaceuticals.

PubMed

Nyadong, Leonard; Harris, Glenn A; Balayssac, Stéphane; Galhena, Asiri S; Malet-Martino, Myriam; Martino, Robert; Parry, R Mitchell; Wang, May Dongmei; Fernández, Facundo M; Gilard, Véronique

2009-06-15

During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered (1)H nuclear magnetic resonance spectroscopy (2D DOSY (1)H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY (1)H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug "chemotyping". In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY (1)H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials.

Continuous flow Overhauser dynamic nuclear polarization of water in the fringe field of a clinical magnetic resonance imaging system for authentic image contrast

PubMed Central

Lingwood, Mark D.; Siaw, Ting Ann; Sailasuta, Napapon; Ross, Brian D.; Bhattacharya, Pratip; Han, Songi

2016-01-01

We describe and demonstrate a system to generate hyperpolarized water in the 0.35 T fringe field of a clinical 1.5 T whole-body magnetic resonance imaging (MRI) magnet. Once generated, the hyperpolarized water is quickly and continuously transferred from the 0.35 T fringe to the 1.5 T center field of the same magnet for image acquisition using standard MRI equipment. The hyperpolarization is based on Overhauser dynamic nuclear polarization (DNP), which effectively and quickly transfers the higher spin polarization of free radicals to nuclear spins at ambient temperatures. We visualize the dispersion of hyperpolarized water as it flows through water-saturated systems by utilizing an observed −15 fold DNP signal enhancement with respect to the unenhanced 1H MRI signal of water at 1.5 T. The experimental DNP apparatus presented here is readily portable and can be brought to and used with any conventional unshielded MRI system. A new method of immobilizing radicals to gel beads via polyelectrolyte linker arms is described, which led to superior flow Overhauser DNP performance compared to previously presented gels. We discuss the general applicability of Overhauser DNP hyperpolarization of water and aqueous solutions in the fringe field of commercially available magnets with central fields up to 4.7 Tesla. PMID:20541445

Synergy and destructive interferences between local magnetic anisotropies in binuclear complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guihéry, Nathalie; Ruamps, Renaud; Maurice, Rémi

2015-12-31

Magnetic anisotropy is responsible for the single molecule magnet behavior of transition metal complexes. This behavior is characterized by a slow relaxation of the magnetization for low enough temperatures, and thus for a possible blocking of the magnetization. This bistable behavior can lead to possible technological applications in the domain of data storage or quantum computing. Therefore, the understanding of the microscopic origin of magnetic anisotropy has received a considerable interest during the last two decades. The presentation focuses on the determination of the anisotropy parameters of both mono-nuclear and bi-nuclear types of complexes and on the control and optimizationmore » of the anisotropic properties. The validity of the model Hamiltonians commonly used to characterize such complexes has been questioned and it is shown that neither the standard multispin Hamiltonian nor the giant spin Hamiltonian are appropriate for weakly coupled ions. Alternative models have been proposed and used to properly extract the relevant parameters. Rationalizations of the magnitude and nature of both local anisotropies of single ions and the molecular anisotropy of polynuclear complexes are provided. The synergy and interference effects between local magnetic anisotropies are studied in a series of binuclear complexes.« less

Water absorption of freeze-dried meat at different water activities: a multianalytical approach using sorption isotherm, differential scanning calorimetry, and nuclear magnetic resonance.

PubMed

Venturi, Luca; Rocculi, Pietro; Cavani, Claudio; Placucci, Giuseppe; Dalla Rosa, Marco; Cremonini, Mauro A

2007-12-26

Hydration of freeze-dried chicken breast meat was followed in the water activity range of aw=0.12-0.99 by a multianalytical approach comprising of sorption isotherm, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The amount of frozen water and the shape of the T2-relaxogram were evaluated at each water content by DSC and NMR, respectively. Data revealed an agreement between sorption isotherm and DSC experiments about the onset of bulk water (aw=0.83-0.86), and NMR detected mobile water starting at aw=0.75. The origin of the short-transverse relaxation time part of the meat NMR signal was also reinvestigated through deuteration experiments and proposed to arise from protons belonging to plasticized matrix structures. It is proved both by D2O experiments and by gravimetry that the extra protons not contributing to the water content in the NMR experiments are about 6.4% of the total proton NMR CPMG signal of meat.

Characterization of proton exchange membrane materials for fuel cells by solid state nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kong, Zueqian

2010-01-01

Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-anglemore » X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel cell, while dispersed water molecules and polymer ribbons account for the structures at low and high hydration levels, respectively.« less

Rheological and nuclear magnetic resonance (NMR) study of the hydration and heating of undeveloped wheat doughs.

PubMed

Lopes-da-Silva, J A; Santos, Dora M J; Freitas, Andreia; Brites, Carla; Gil, Ana M

2007-07-11

The undeveloped doughs of two wheat flours differing in technological performance were characterized at the supramolecular level, by fundamental small-deformation oscillatory rheology and shear viscometry, and at the molecular level, by nuclear magnetic resonance (NMR) spectroscopy. For the harder variety, the higher storage moduli indicated lower mobility of the protein/water matrix in the 0.001-100 s range. Conversely, 1H NMR indicated higher molecular mobility in the sub-microsecond range for protein/water, whereas starch was found to be generally more hindered. It is suggested that faster protein/water motions are at the basis of the higher structural rearrangement indicated by tan delta for the harder variety. Rheological effects of heating-cooling reflect mainly starch behavior, whereas 1H NMR spectra and relaxation times give additional information on component mixing and molecular mobility. The heated softer variety dough formed a rigid lattice and, although a similar tendency was seen for the hard variety, all of its components remained more mobile. About 60% of starch crystallizes in both varieties, which may explain their similar rheological behaviors upon cooling.

Pulsed-High Field/High-Frequency EPR Spectroscopy

NASA Astrophysics Data System (ADS)

Fuhs, Michael; Moebius, Klaus

Pulsed high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy is used to disentangle many kinds of different effects often obscured in continuous wave (cw) EPR spectra at lower magnetic fields/microwave frequencies. While the high magnetic field increases the resolution of G tensors and of nuclear Larmor frequencies, the high frequencies allow for higher time resolution for molecular dynamics as well as for transient paramagnetic intermediates studied with time-resolved EPR. Pulsed EPR methods are used for example for relaxation-time studies, and pulsed Electron Nuclear DOuble Resonance (ENDOR) is used to resolve unresolved hyperfine structure hidden in inhomogeneous linewidths. In the present article we introduce the basic concepts and selected applications to structure and mobility studies on electron transfer systems, reaction centers of photosynthesis as well as biomimetic models. The article concludes with an introduction to stochastic EPR which makes use of an other concept for investigating resonance systems in order to increase the excitation bandwidth of pulsed EPR. The limited excitation bandwidth of pulses at high frequency is one of the main limitations which, so far, made Fourier transform methods hardly feasible.

Nuclear magnetic resonance (NMR)-based metabolomics for cancer research.

PubMed

Ranjan, Renuka; Sinha, Neeraj

2018-05-07

Nuclear magnetic resonance (NMR) has emerged as an effective tool in various spheres of biomedical research, amongst which metabolomics is an important method for the study of various types of disease. Metabolomics has proved its stronghold in cancer research by the development of different NMR methods over time for the study of metabolites, thus identifying key players in the aetiology of cancer. A plethora of one-dimensional and two-dimensional NMR experiments (in solids, semi-solids and solution phases) are utilized to obtain metabolic profiles of biofluids, cell extracts and tissue biopsy samples, which can further be subjected to statistical analysis. Any alteration in the assigned metabolite peaks gives an indication of changes in metabolic pathways. These defined changes demonstrate the utility of NMR in the early diagnosis of cancer and provide further measures to combat malignancy and its progression. This review provides a snapshot of the trending NMR techniques and the statistical analysis involved in the metabolomics of diseases, with emphasis on advances in NMR methodology developed for cancer research. Copyright © 2018 John Wiley & Sons, Ltd.

1,1-dimethylhydrazine as a high purity nitrogen source for MOVPE-water reduction and quantification using nuclear magnetic resonance, gas chromatography-atomic emission detection spectroscopy and cryogenic-mass spectroscopy analytical techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odedra, R.; Smith, L.M.; Rushworth, S.A.

2000-01-01

Hydrazine derivatives are attractive low temperature nitrogen sources for use in MOVPE due to their low thermal stability. However their purification and subsequent analysis has not previously been investigated in depth for this application. A detailed study on 1,1-dimethylhydrazine {l{underscore}brace}(CH{sub 3}){sub 2}N-NH{sub 2}{r{underscore}brace} purified by eight different methods and the subsequent quantitative measurements of water present in the samples obtained is reported here. A correlation between {sup 1}H nuclear magnetic resonance spectroscopy (NMR), gas chromatography-atomic emission detection (GC-AED) and cryogenic mass spectroscopy (Cryogenic-MS) has been performed. All three analysis techniques can be used to measure water in the samples andmore » with the best purification the water content can be lowered well below 100 ppm. The high purity of this material has been demonstrated by growth results and the state-of-the-art performance of laser diodes.« less

Metabolomics by Proton High-Resolution Magic-Angle-Spinning Nuclear Magnetic Resonance of Tomato Plants Treated with Two Secondary Metabolites Isolated from Trichoderma.

PubMed

Mazzei, Pierluigi; Vinale, Francesco; Woo, Sheridan Lois; Pascale, Alberto; Lorito, Matteo; Piccolo, Alessandro

2016-05-11

Trichoderma fungi release 6-pentyl-2H-pyran-2-one (1) and harzianic acid (2) secondary metabolites to improve plant growth and health protection. We isolated metabolites 1 and 2 from Trichoderma strains, whose different concentrations were used to treat seeds of Solanum lycopersicum. The metabolic profile in the resulting 15 day old tomato leaves was studied by high-resolution magic-angle-spinning nuclear magnetic resonance (HRMAS NMR) spectroscopy directly on the whole samples without any preliminary extraction. Principal component analysis (PCA) of HRMAS NMR showed significantly enhanced acetylcholine and γ-aminobutyric acid (GABA) content accompanied by variable amount of amino acids in samples treated with both Trichoderma secondary metabolites. Seed germination rates, seedling fresh weight, and the metabolome of tomato leaves were also dependent upon doses of metabolites 1 and 2 treatments. HRMAS NMR spectroscopy was proven to represent a rapid and reliable technique for evaluating specific changes in the metabolome of plant leaves and calibrating the best concentration of bioactive compounds required to stimulate plant growth.

A nuclear magnetic resonance study of the dynamics of organofluorine interactions with a dissolved humic acid.

PubMed

Longstaffe, James G; Courtier-Murias, Denis; Simpson, Andre J

2016-02-01

A quantitative understanding of the dynamics of the interactions between organofluorine compounds and humic acids will contribute to an improved understanding of the role that Natural Organic Matter plays as a mediator in the fate, transport and distribution of these contaminants in the environment. Here, Nuclear Magnetic Resonance (NMR) spectroscopy-based diffusion measurements are used to estimate the association dynamics between dissolved humic acid and selected organofluorine compounds: pentafluoroaniline, pentafluorophenol, potassium perfluorooctane sulfonate, and perfluorooctanoic acid. Under the conditions used here, the strength of the association with humic acid increases linearly as temperature decreases for all compounds except for perfluorooctanoic acid, which exhibits divergent behavior with a non-linear decrease in the extent of interaction as temperature decreases. A general interaction mechanism controlled largely by desolvation effects is suggested for all compounds examined here except for perfluorooctanoic acid, which exhibits a specific mode of interaction consistent with a proteinaceous binding site. Reverse Heteronuclear Saturation Transfer Difference NMR is used to confirm the identity and nature of the humic acid binding sites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural characterization of hemicelluloses and topochemical changes in Eucalyptus cell wall during alkali ethanol treatment.

PubMed

Li, Han-Yin; Sun, Shao-Ni; Zhou, Xia; Peng, Feng; Sun, Run-Cang

2015-06-05

Eucalyptus was sequentially extracted with 70% ethanol containing 0.4, 1.0, 2.0, 3.0, and 5.0% NaOH for 2h at 80°C. The chemical composition and structural features of the hemicellulosic fractions obtained were comparatively characterized by the combination of high-performance anion-exchange chromatography, gel permeation chromatography, Fourier transform infrared, and nuclear magnetic resonance spectroscopies. Furthermore, the main component distribution and their changes in cell wall were investigated by confocal Raman microscopy. Based on the Fourier transform infrared and nuclear magnetic resonance analyses, the hemicelluloses extracted from Eucalyptus mainly have a linear backbone of (1→4)-linked-β-d-xylopyranosyl residues decorated with branch at O-2 of 4-O-methyl-α-glucuronic acid unit. Raman analysis revealed that the dissolution of hemicelluloses was different in the morphological regions, and the hemicelluloses released mainly originated from the secondary wall. The information obtained from the study conducted by combining chemical characterization with ultrastructure provides important basis for studying the mechanism of the alkali treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

The solution structure of a local anesthetic and phospholipids: Conformational analysis by one- and two-dimensional nuclear magnetic resonance spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basti, M.M.

1988-01-01

Both sections of this study include the use of several high-resolution nuclear magnetic resonance (NMR) techniques. The first part is concerned with the conformational analysis of dibucaine (a local anesthetic) by the use of the lanthanide shift reagent Yb(fod){sub 3} and by computer calculations. The second part of the dissertation is concerned with the study of dioctanoylphosphatidylcholine and dodecylphosphorylcholine and the sulfur analogues of these molecules in deuterated chloroform and chloroform/methanol (2:1 v/v). 2D COSY and {sup 1}H-{sup 13}C heteronuclear correlation experiments were used to make {sup 1}H and {sup 13}C assignments. In both analogues of the phosphatidylcholine molecule, themore » three-bond {sup 1}H-{sup 1}H, {sup 31}P-{sup 13}C, and {sup 31}P-{sup 1}H coupling constants were measured using {sup 1}H, {sup 13}C and {sup 31}P NMR spectroscopy. A number of these coupling constants were significantly different between the two analogues.« less

Rapid Identification of Candida Species by Using Nuclear Magnetic Resonance Spectroscopy and a Statistical Classification Strategy

PubMed Central

Himmelreich, Uwe; Somorjai, Ray L.; Dolenko, Brion; Lee, Ok Cha; Daniel, Heide-Marie; Murray, Ronan; Mountford, Carolyn E.; Sorrell, Tania C.

2003-01-01

Nuclear magnetic resonance (NMR) spectra were acquired from suspensions of clinically important yeast species of the genus Candida to characterize the relationship between metabolite profiles and species identification. Major metabolites were identified by using two-dimensional correlation NMR spectroscopy. One-dimensional proton NMR spectra were analyzed by using a staged statistical classification strategy. Analysis of NMR spectra from 442 isolates of Candida albicans, C. glabrata, C. krusei, C. parapsilosis, and C. tropicalis resulted in rapid, accurate identification when compared with conventional and DNA-based identification. Spectral regions used for the classification of the five yeast species revealed species-specific differences in relative amounts of lipids, trehalose, polyols, and other metabolites. Isolates of C. parapsilosis and C. glabrata with unusual PCR fingerprinting patterns also generated atypical NMR spectra, suggesting the possibility of intraspecies discontinuity. We conclude that NMR spectroscopy combined with a statistical classification strategy is a rapid, nondestructive, and potentially valuable method for identification and chemotaxonomic characterization that may be broadly applicable to fungi and other microorganisms. PMID:12902244

Decoherence and fluctuation dynamics of the quantum dot nuclear spin bath probed by nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Chekhovich, Evgeny A.

2017-06-01

Dynamics of nuclear spin decoherence and nuclear spin flip-flops in self-assembled InGaAs/GaAs quantum dots are studied experimentally using optically detected nuclear magnetic resonance (NMR). Nuclear spin-echo decay times are found to be in the range 1-4 ms. This is a factor of ~3 longer than in strain-free GaAs/AlGaAs structures and is shown to result from strain-induced quadrupolar effects that suppress nuclear spin flip-flops. The correlation times of the flip-flops are examined using a novel frequency-comb NMR technique and are found to exceed 1 s, a factor of ~1000 longer than in strain-free structures. These findings complement recent studies of electron spin coherence and reveal the paradoxical dual role of the quadrupolar effects in self-assembled quantum dots: large increase of the nuclear spin bath coherence and at the same time significant reduction of the electron spin-qubit coherence. Approaches to increasing electron spin coherence are discussed. In particular the nanohole filled GaAs/AlGaAs quantum dots are an attractive option: while their optical quality matches the self-assembled dots the quadrupolar effects measured in NMR spectra are a factor of 1000 smaller.

Beta-hairpin formation in aqueous solution and in the presence of trifluoroethanol: a (1)H and (13)C nuclear magnetic resonance conformational study of designed peptides.

PubMed

Santiveri, Clara M; Pantoja-Uceda, David; Rico, Manuel; Jiménez, M Angeles

2005-10-15

In order to check our current knowledge on the principles involved in beta-hairpin formation, we have modified the sequence of a 3:5 beta-hairpin forming peptide with two different purposes, first to increase the stability of the formed 3:5 beta-hairpin, and second to convert the 3:5 beta-hairpin into a 2:2 beta-hairpin. The conformational behavior of the designed peptides was investigated in aqueous solution and in 30% trifluoroethanol (TFE) by analysis of the following nuclear magnetic resonance (NMR) parameters: nuclear Overhauser effect (NOE) data, and C(alpha)H, (13)C(alpha), and (13)C(beta) conformational shifts. From the differences in the ability to adopt beta-hairpin structures in these peptides, we have arrived to the following conclusions: (i) beta-Hairpin population increases with the statistical propensity of residues to occupy each turn position. (ii) The loop length, and in turn, the beta-hairpin type, can be modified as a function of the type of turn favored by the loop sequence. These two conclusions reinforce previous results about the importance of beta-turn sequence in beta-hairpin folding. (iii) Side-chain packing on each face of the beta-sheet may play a major role in beta-hairpin stability; hence simplified analysis in terms of isolated pair interactions and intrinsic beta-sheet propensities is insufficient. (iv) Contributions to beta-hairpin stability of turn and strand sequences are not completely independent. (v) The burial of hydrophobic surface upon beta-hairpin formation that, in turn, depends on side-chain packing also contributes to beta-hairpin stability. (vi) As previously observed, TFE stabilizes beta-hairpin structures, but the extent of the contribution of different factors to beta-hairpin formation is sometimes different in aqueous solution and in 30% TFE. (c) 2005 Wiley Periodicals, Inc. Biopolymers 79: 150-162, 2005.

Local dynamic nuclear polarization using quantum point contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wald, K.R.; Kouwenhoven, L.P.; McEuen, P.L.

1994-08-15

We have used quantum point contacts (QPCs) to locally create and probe dynamic nuclear polarization (DNP) in GaAs heterostructures in the quantum Hall regime. DNP is created via scattering between spin-polarized Landau level electrons and the Ga and As nuclear spins, and it leads to hysteresis in the dc transport characteristics. The nuclear origin of this hysteresis is demonstrated by nuclear magnetic resonance (NMR). Our results show that QPCs can be used to create and probe local nuclear spin populations, opening up new possibilities for mesoscopic NMR experiments.

Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors

NASA Astrophysics Data System (ADS)

Franke, David P.; Hrubesch, Florian M.; Künzl, Markus; Becker, Hans-Werner; Itoh, Kohei M.; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S.

2015-07-01

The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S11=1.5 ×1022 V /m2 and S44=6 ×1022 V /m2 . We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling.

Theory of Nuclear Quadrupole Interactions in the Chemical Ferromagnet p-Cl-Ph-CH-N=TEMPO

NASA Astrophysics Data System (ADS)

Briere, Tina M.; Jeong, Junho; Sahoo, N.; Das, T. P.; Ohira, S.; Nishiyama, K.; Nagamine, K.

2002-03-01

The study(Junho Jeong et al., Physica B 289-290, 132 (2000).) of the magnetic hyperfine properties of chemical ferromagnets provides valuable information about the electronic spin distributions in the individual molecules. Insights into the electronic charge distributions and their anisotropy can be obtained from electric quadrupole interactions for the different nuclei in these systems. For this purpose we have studied the nuclear quadrupole interactions(T. P. Das and E. L. Hahn "Nuclear Quadrupole Resonance Spectroscopy", Academic Press Inc., New York, 1958.) for the 14^N nuclei in the NO group and the bridge nitrogen, the 17^O nucleus in the NO group and the 35^Cl nucleus in the p-Cl-Ph-CH-N=TEMPO system both by itself and in the presence of trapped μ and Mu. Comparison will be made between our results and available experimental quadrupole coupling constant (e^2qQ) and asymmetry parameter (η) data.

Nuclear quadrupole resonance lineshape analysis for different motional models: Stochastic Liouville approach

NASA Astrophysics Data System (ADS)

Kruk, D.; Earle, K. A.; Mielczarek, A.; Kubica, A.; Milewska, A.; Moscicki, J.

2011-12-01

A general theory of lineshapes in nuclear quadrupole resonance (NQR), based on the stochastic Liouville equation, is presented. The description is valid for arbitrary motional conditions (particularly beyond the valid range of perturbation approaches) and interaction strengths. It can be applied to the computation of NQR spectra for any spin quantum number and for any applied magnetic field. The treatment presented here is an adaptation of the "Swedish slow motion theory," [T. Nilsson and J. Kowalewski, J. Magn. Reson. 146, 345 (2000), 10.1006/jmre.2000.2125] originally formulated for paramagnetic systems, to NQR spectral analysis. The description is formulated for simple (Brownian) diffusion, free diffusion, and jump diffusion models. The two latter models account for molecular cooperativity effects in dense systems (such as liquids of high viscosity or molecular glasses). The sensitivity of NQR slow motion spectra to the mechanism of the motional processes modulating the nuclear quadrupole interaction is discussed.

High-nuclearity mixed-valence clusters and mixed-valence chains: general approach to the calculation of the energy levels and bulk magnetic properties.

PubMed

Clemente-Juan, J M; Borrás-Almenar, J J; Coronado, E; Palii, A V; Tsukerblat, B S

2009-05-18

A general approach to the problem of electron delocalization in the high-nuclearity mixed-valence (MV) clusters containing an arbitrary number of localized spins and itinerant electrons is developed. Along with the double exchange, we consider the isotropic magnetic exchange between the localized electrons as well as the Coulomb intercenter repulsion. As distinguished from the previous approaches dealing with the MV systems in which itinerant electrons are delocalized over all constituent metal sites, here, we consider a more common case of systems exhibiting partial delocalization and containing several delocalized domains. Taking full advantage of the powerful angular momentum technique, we were able to derive closed form analytical expressions for the matrix elements of the full Hamiltonian. These expressions provide an efficient tool for treating complex mixed-valence systems, because they contain only products of 6j-symbols (that appear while treating the delocalized parts) and 9j-symbols (exchange interactions in localized parts) and do not contain high-order recoupling coefficients and 3j-symbols that essentially constrained all previous theories of mixed valency. The approach developed here is accompanied by an efficient computational procedure that allows us to calculate the bulk thermodynamic properties (magnetic susceptibility, magnetization, and magnetic specific heat) of high-nuclearity MV clusters. Finally, this approach has been used to discuss the magnetic properties of the octanuclear MV cluster [Fe(8)(mu(4)-O)(4)(4-Cl-pz)(12)Cl(4)](-) and the diphthalocyanine chains [YPc(2)].CH(2)Cl(2) and [ScPc(2)].CH(2)Cl(2) composed of MV dimers interacting through the magnetic exchange and Coulomb repulsion.

Fingerprints of single nuclear spin energy levels using STM - ENDOR

NASA Astrophysics Data System (ADS)

Manassen, Yishay; Averbukh, Michael; Jbara, Moamen; Siebenhofer, Bernhard; Shnirman, Alexander; Horovitz, Baruch

2018-04-01

We performed STM-ENDOR experiments where the intensity of one of the hyperfine components detected in ESR-STM is recorded while an rf power is irradiated into the tunneling junction and its frequency is swept. When the latter frequency is near a nuclear transition a dip in ESR-STM signal is observed. This experiment was performed in three different systems: near surface SiC vacancies where the electron spin is coupled to a next nearest neighbor 29Si nucleus; Cu deposited on Si(111)7x7 surface, where the unpaired electron of the Cu atom is coupled to the Cu nucleus (63Cu, 65Cu) and on Tempo molecules adsorbed on Au(111), where the unpaired electron is coupled to a Nitrogen nucleus (14N). While some of the hyperfine values are unresolved in the ESR-STM data due to linewidth we find that they are accurately determined in the STM-ENDOR data including those from remote nuclei, which are not detected in the ESR-STM spectrum. Furthermore, STM-ENDOR can measure single nuclear Zeeman frequencies, distinguish between isotopes through their different nuclear magnetic moments and detect quadrupole spectra. We also develop and solve a Bloch type equation for the coupled electron-nuclear system that facilitates interpretation of the data. The improved spectral resolution of STM - ENDOR opens many possibilities for nanometric scale chemical analysis.

Fingerprints of single nuclear spin energy levels using STM - ENDOR.

PubMed

Manassen, Yishay; Averbukh, Michael; Jbara, Moamen; Siebenhofer, Bernhard; Shnirman, Alexander; Horovitz, Baruch

2018-04-01

We performed STM-ENDOR experiments where the intensity of one of the hyperfine components detected in ESR-STM is recorded while an rf power is irradiated into the tunneling junction and its frequency is swept. When the latter frequency is near a nuclear transition a dip in ESR-STM signal is observed. This experiment was performed in three different systems: near surface SiC vacancies where the electron spin is coupled to a next nearest neighbor 29 Si nucleus; Cu deposited on Si(111)7x7 surface, where the unpaired electron of the Cu atom is coupled to the Cu nucleus ( 63 Cu, 65 Cu) and on Tempo molecules adsorbed on Au(111), where the unpaired electron is coupled to a Nitrogen nucleus ( 14 N). While some of the hyperfine values are unresolved in the ESR-STM data due to linewidth we find that they are accurately determined in the STM-ENDOR data including those from remote nuclei, which are not detected in the ESR-STM spectrum. Furthermore, STM-ENDOR can measure single nuclear Zeeman frequencies, distinguish between isotopes through their different nuclear magnetic moments and detect quadrupole spectra. We also develop and solve a Bloch type equation for the coupled electron-nuclear system that facilitates interpretation of the data. The improved spectral resolution of STM - ENDOR opens many possibilities for nanometric scale chemical analysis. Copyright © 2018 Elsevier Inc. All rights reserved.

Neutronics Comparison Analysis of the Water Cooled Ceramics Breeding Blanket for CFETR

NASA Astrophysics Data System (ADS)

Li, Jia; Zhang, Xiaokang; Gao, Fangfang; Pu, Yong

2016-02-01

China Fusion Engineering Test Reactor (CFETR) is an ITER-like fusion engineering test reactor that is intended to fill the scientific and technical gaps between ITER and DEMO. One of the main missions of CFETR is to achieve a tritium breeding ratio that is no less than 1.2 to ensure tritium self-sufficiency. A concept design for a water cooled ceramics breeding blanket (WCCB) is presented based on a scheme with the breeder and the multiplier located in separate panels for CFETR. Based on this concept, a one-dimensional (1D) radial built breeding blanket was first designed, and then several three-dimensional models were developed with various neutron source definitions and breeding blanket module arrangements based on the 1D radial build. A set of nuclear analyses have been carried out to compare the differences in neutronics characteristics given by different calculation models, addressing neutron wall loading (NWL), tritium breeding ratio (TBR), fast neutron flux on inboard side and nuclear heating deposition on main in-vessel components. The impact of differences in modeling on the nuclear performance has been analyzed and summarized regarding the WCCB concept design. supported by the National Special Project for Magnetic Confined Nuclear Fusion Energy (Nos. 2013GB108004, 2014GB122000, and 2014GB119000), and National Natural Science Foundation of China (No. 11175207)

Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet.

PubMed

Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P; Keiderling, Uwe; Ono, Kanta

2016-06-20

We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.

Multiple magnetic scattering in small-angle neutron scattering of Nd–Fe–B nanocrystalline magnet

PubMed Central

Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta

2016-01-01

We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd–Fe–B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd–Fe–B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd–Fe–B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters. PMID:27321149

Spider Silk: From Protein-Rich Gland Fluids to Diverse Biopolymer Fibers

DTIC Science & Technology

2016-01-06

characterize the protein-rich fluid in the various spider silk producing glands. We have been using a battery of magnetic resonance methods including...solution and solid-state nuclear magnetic resonance (NMR) and micro imaging (MRI) in combination with wide angle and small angle X-ray diffraction...range of magnetic resonance methods. We successfully developed magnetic resonance imaging (MRI) techniques with localized spectroscopy to probe the silk

Direct enhancement of nitrogen-15 targets at high-field by fast ADAPT-SABRE

NASA Astrophysics Data System (ADS)

Roy, Soumya S.; Stevanato, Gabriele; Rayner, Peter J.; Duckett, Simon B.

2017-12-01

Signal Amplification by Reversible Exchange (SABRE) is an attractive nuclear spin hyperpolarization technique capable of huge sensitivity enhancement in nuclear magnetic resonance (NMR) detection. The resonance condition of SABRE hyperpolarization depends on coherent spin mixing, which can be achieved naturally at a low magnetic field. The optimum transfer field to spin-1/2 heteronuclei is technically demanding, as it requires field strengths weaker than the earth's magnetic field for efficient spin mixing. In this paper, we illustrate an approach to achieve strong 15N SABRE hyperpolarization at high magnetic field by a radio frequency (RF) driven coherent transfer mechanism based on alternate pulsing and delay to achieve polarization transfer. The presented scheme is found to be highly robust and much faster than existing related methods, producing ∼ 3 orders of magnitude 15N signal enhancement within 2 s of RF pulsing.

Direct enhancement of nitrogen-15 targets at high-field by fast ADAPT-SABRE.

PubMed

Roy, Soumya S; Stevanato, Gabriele; Rayner, Peter J; Duckett, Simon B

2017-12-01

Signal Amplification by Reversible Exchange (SABRE) is an attractive nuclear spin hyperpolarization technique capable of huge sensitivity enhancement in nuclear magnetic resonance (NMR) detection. The resonance condition of SABRE hyperpolarization depends on coherent spin mixing, which can be achieved naturally at a low magnetic field. The optimum transfer field to spin-1/2 heteronuclei is technically demanding, as it requires field strengths weaker than the earth's magnetic field for efficient spin mixing. In this paper, we illustrate an approach to achieve strong 15 N SABRE hyperpolarization at high magnetic field by a radio frequency (RF) driven coherent transfer mechanism based on alternate pulsing and delay to achieve polarization transfer. The presented scheme is found to be highly robust and much faster than existing related methods, producing ∼3 orders of magnitude 15 N signal enhancement within 2 s of RF pulsing. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Nuclear magnetic resonance properties of lunar samples.

NASA Technical Reports Server (NTRS)

Kline, D.; Weeks, R. A.

1972-01-01

Nuclear magnetic resonance spectra of Na-23, Al-27, and P-31 in fines samples 10084,60 and 14163,168 and in crystalline rock samples 12021,55 and 14321,166, have been recorded over a range of frequencies up to 20 MHz. A shift in the field at which maximum absorption occurs for all of the spectra relative to the field at which maximum absorption occurs for terrestrial analogues is attributed to a sample-dependent magnetic field at the Na, Al, and P sites opposing the laboratory field. The magnitude of these fields internal to the samples is sample dependent and varies from 5 to 10 G. These fields do not correlate with the iron content of the samples. However, the presence of single-domain particles of iron distributed throughout the plagioclase fraction that contains the principal fraction of Na and Al is inferred from electron magnetic resonance spectra shapes.

Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

PubMed

Zhang, Z T; Xu, C; Dmytriieva, D; Molatta, S; Wosnitza, J; Wang, Y T; Helm, M; Zhou, Shengqiang; Kühne, H

2017-10-20

We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13 C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13 C nuclear spin-lattice relaxation rate [Formula: see text] by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of [Formula: see text] below about 10 K can well be described by a thermally activated form, [Formula: see text], yielding a singular Zeeman energy of ([Formula: see text]) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments.

Nuclear reactor shutdown system

DOEpatents

Bhate, Suresh K.; Cooper, Martin H.; Riffe, Delmar R.; Kinney, Calvin L.

1981-01-01

An inherent shutdown system for a nuclear reactor having neutron absorbing rods affixed to an armature which is held in an upper position by a magnetic flux flowing through a Curie temperature material. The Curie temperature material is fixedly positioned about the exterior of an inner duct in an annular region through which reactor coolant flows. Elongated fuel rods extending from within the core upwardly toward the Curie temperature material are preferably disposed within the annular region. Upon abnormal conditions which result in high neutron flux and coolant temperature, the Curie material loses its magnetic permeability, breaking the magnetic flux path and allowing the armature and absorber rods to drop into the core, thus shutting down the fissioning reaction. The armature and absorber rods are retrieved by lowering the housing for the electromagnet forming coils which create a magnetic flux path which includes the inner duct wall. The coil housing then is raised, resetting the armature.

Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meier, Thomas; Herzig, Tobias; Haase, Jürgen

2014-04-15

A new design of a non-magnetic high-pressure anvil cell for nuclear magnetic resonance (NMR) experiments at Giga-Pascal pressures is presented, which uses a micro-coil inside the pressurized region for high-sensitivity NMR. The comparably small cell has a length of 22 mm and a diameter of 18 mm, so it can be used with most NMR magnets. The performance of the cell is demonstrated with external-force vs. internal-pressure experiments, and the cell is shown to perform well at pressures up to 23.5 GPa using 800 μm 6H-SiC large cone Boehler-type anvils. {sup 1}H, {sup 23}Na, {sup 27}Al, {sup 69}Ga, and {supmore » 71}Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.« less

Spin-lattice relaxation of optically polarized nuclei in p -type GaAs

NASA Astrophysics Data System (ADS)

Kotur, M.; Dzhioev, R. I.; Vladimirova, M.; Cherbunin, R. V.; Sokolov, P. S.; Yakovlev, D. R.; Bayer, M.; Suter, D.; Kavokin, K. V.

2018-04-01

Spin-lattice relaxation of the nuclear spin system in p -type GaAs is studied using a three-stage experimental protocol including optical pumping and measuring the difference of the nuclear spin polarization before and after a dark interval of variable length. This method allows us to measure the spin-lattice relaxation time T1 of optically pumped nuclei "in the dark," that is, in the absence of illumination. The measured T1 values fall into the subsecond time range, being three orders of magnitude shorter than in earlier studied n -type GaAs. The drastic difference is further emphasized by magnetic-field and temperature dependencies of T1 in p -GaAs, showing no similarity to those in n -GaAs. This unexpected behavior finds its explanation in the spatial selectivity of the optical pumping in p -GaAs, that is only efficient in the vicinity of shallow donors, together with the quadrupole relaxation of nuclear spins, which is induced by electric fields within closely spaced donor-acceptor pairs. The developed theoretical model explains the whole set of experimental results.

Magnetic manipulation of nanorods in the nucleus of living cells.

PubMed

Celedon, Alfredo; Hale, Christopher M; Wirtz, Denis

2011-10-19

The organization of chromatin in the cell nucleus is crucial for gene expression regulation. However, physically probing the nuclear interior is challenging because high forces have to be applied using minimally invasive techniques. Here, magnetic nanorods embedded in the nucleus of living cells are subjected to controlled rotational forces, producing micron-sized displacements in the nuclear interior. The resulting time-dependent rotation of the nanorods is analyzed in terms of viscoelastic parameters of the nucleus, in wild-type and Lamin A/C deficient cells. This method and analysis reveal that Lamin A/C knockout, together perhaps with other changes that result from the knockout, induce significant decreases in the nuclear viscosity and elasticity. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Nuclear resonance reflectivity from a [57Fe/Cr]30 multilayer with the Synchrotron Mössbauer Source.

PubMed

Andreeva, Marina A; Baulin, Roman A; Chumakov, Aleksandr I; Rüffer, Rudolf; Smirnov, Gennadii V; Babanov, Yurii A; Devyaterikov, Denis I; Milyaev, Mikhail A; Ponomarev, Dmitrii A; Romashev, Lazar N; Ustinov, Vladimir V

2018-03-01

Mössbauer reflectivity spectra and nuclear resonance reflectivity (NRR) curves have been measured using the Synchrotron Mössbauer Source (SMS) for a [ 57 Fe/Cr] 30 periodic multilayer, characterized by the antiferromagnetic interlayer coupling between adjacent 57 Fe layers. Specific features of the Mössbauer reflectivity spectra measured with π-polarized radiation of the SMS near the critical angle and at the `magnetic' maximum on the NRR curve are analyzed. The variation of the ratio of lines in the Mössbauer reflectivity spectra and the change of the intensity of the `magnetic' maximum under an applied external field has been used to reveal the transformation of the magnetic alignment in the investigated multilayer.

Introduction to Nuclear Magnetic Resonance

NASA Technical Reports Server (NTRS)

Manatt, Stanley L.

1985-01-01

The purpose of this paper is to try to give a short overview of what the status is on nuclear magnetic resonance (NMR). It's a subject where one really has to spend some time to look at the physics in detail to develop a proper working understanding. I feel it's not appropriate to present to you density matrices, Hamiltonians of all sorts, and differential equations representing the motion of spins. I'm really going to present some history and status, and show a few very simple concepts involved in NMR. It is a form of radio frequency spectroscopy and there are a great number of nuclei that can be studied very usefully with the technique. NMR requires a magnet, a r.f. transmitter/receiver system, and a data acquisition system.

Natural chemical shielding analysis of nuclear magnetic resonance shielding tensors from gauge-including atomic orbital calculations

NASA Astrophysics Data System (ADS)

Bohmann, Jonathan A.; Weinhold, Frank; Farrar, Thomas C.

1997-07-01

Nuclear magnetic shielding tensors computed by the gauge including atomic orbital (GIAO) method in the Hartree-Fock self-consistent-field (HF-SCF) framework are partitioned into magnetic contributions from chemical bonds and lone pairs by means of natural chemical shielding (NCS) analysis, an extension of natural bond orbital (NBO) analysis. NCS analysis complements the description provided by alternative localized orbital methods by directly calculating chemical shieldings due to delocalized features in the electronic structure, such as bond conjugation and hyperconjugation. Examples of NCS tensor decomposition are reported for CH4, CO, and H2CO, for which a graphical mnemonic due to Cornwell is used to illustrate the effect of hyperconjugative delocalization on the carbon shielding.

High-energy transients. [from weakly and strongly magnetic neutron stars

NASA Technical Reports Server (NTRS)

Lamb, D. Q.

1991-01-01

The observational characteristics of X-ray bursts are reviewed and the thermonuclear-flash model is examined to assess the suitability of the model and the sources of X- and gamma-ray bursts. The profiles of X-ray bursts from five different sources are delineated, and the global analysis of nuclear burning is discussed to review th range possible X-ray burst behavior. The analysis by Fushiki and Lamb (1987) is noted for the description of regions which lie away from the steady-state cut. The discussion of cyclotron lines in gamma-ray bursts emphasizes the source GB880205, and it is shown that Raman and cyclotron resonant scattering can explain the observed positions, strengths, and widths of the dips in the spectrum. X-ray bursts are theorized to emanate from weakly magnetic neutron stars, and gamma-ray bursts are shown to be the products of strongly magnetic neutron stars.

Atypical β-Catenin Activated Child Hepatocellular Tumor

PubMed Central

Unlu, Havva Akmaz; Karakus, Esra; Yazal Erdem, Arzu; Yakut, Zeynep Ilerisoy

2015-01-01

Hepatocellular adenomas are a benign, focal, hepatic neoplasm that have been divided into four subtypes according to the genetic and pathological features. The β-catenin activated subtype accounts for 10-15% of all hepatocellular adenomas and specific magnetic resonance imaging features have been defined for different hepatocellular adenomas subtypes. The current study aimed to report the magnetic resonance imaging features of a well differentiated hepatocellular carcinoma that developed on the basis of β-catenin activated hepatocellular adenomas in a child. In this case, atypical diffuse steatosis was determined in the lesion. In the literature, diffuse steatosis, which is defined as a feature of the hepatocyte nuclear factor-1α-inactivated hepatocellular adenomas subtype, has not been previously reported in any β-catenin activated hepatocellular adenomas case. Interlacing magnetic resonance imaging findings between subtypes show that there are still many mysteries about this topic and larger studies are warranted. PMID:26157702

Magnetic Field Design for the LANL nEDM Experiment

NASA Astrophysics Data System (ADS)

Dadisman, Ryan

2017-09-01

A recent UCN source upgrade at LANSCE makes possible an order of magnitude advancement in the measurement of the neutron electric dipole moment by use of the familiar Ramsey method of separated oscillatory fields. A highly uniform B0 magnetic field is required to achieve sufficiently long spin-relaxation times and to suppress the false EDM caused by the geometric phase effect. We identified a multi-gap solenoid as an ideal candidate to simultaneously achieve the uniformity requirements, via optimization of the gap lengths between and current within different sections, and provide plentiful access to the fiducial region. Results from initial tests of the coil when installed in the magnetic shield house enclosing the experiment will be presented. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-SC-0014622.

Magnetic rotation (MR) band-crossing at high spin states: Role of nucleons in this crossing in N = 78 odd-Z isotones

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Garg, Ritika; Mandal, Samit Kumar

2013-02-01

Magnetic-dipole rotational (MR) bands were discovered about 15 years ago, and have been explained using shears mechanism. The theoretical understanding of these bands has been provided using tilted axis cranking (TAC). At present, magnetic rotation has been seen in whole nuclear landscape and about 180 bands in 80 nuclides has been observed in mass regions A=20, 60, 80, 110, 135 and 195 respectively. The crossing of these bands (ΔI = 1) is very much similar to normal band crossing (ΔI = 2) and already exhibited in different mass regions. We have observed new MR bands and their crossing in the A = 130 mass region in 135La, 137Pr and 139Pm nuclei. The systematic evolution of this phenomenon in N=78 odd-Z isotones leads us to understand the role on nucleons in this crossing.

The application of magnetic resonance microimaging to the visible light curing of dental resins. 3. Stray-field nuclear magnetic resonance imaging (STRAFI).

PubMed

Lloyd, C H; Scrimgeour, S N; Lane, D M; Hunter, G; McDonald, P J

2001-09-01

To investigate the application of stray-field nuclear magnetic resonance imaging (STRAFI) to the visible light curing of dental restorative materials. STRAFI can overcome peak broadening associated with the conventional magnetic resonance microimaging (MRM) of glassy polymers, and has the potential to image dental restorative resins at both low and high degrees of conversion. Cylindrical composite specimens were light-cured from one end to produce some that were fully cured throughout their length and others that were fully cured at one end and uncured at the other. A one-dimensional probe was used to measure the magnetisation in 40 microm thick slices at 100 microm intervals along the length of the specimen. A quadrature pulse sequence was applied and the magnetisation decay recorded in a train of eight echoes. A value for T(2) could be obtained only for the polymer (59+/-16 microms), therefore the echoes were summed to give an approximate indication of the degree of conversion. The echo sum for the monomer was significantly higher than that for the polymer. Differences in composite shade and cure time produced changes in the cure profiles. STRAFI produced measurements for both monomer and polymer in all stages of conversion that allowed cure profiles to be produced. Summing the decay echoes produced a qualitative measure of the condition of the material in the selected slice. The same data can be used to calculate T(2), a quantitative parameter. This first investigation has demonstrated that STRAFI is well suited to polymerisation studies.

Structural Insights into the Calcium-Mediated Allosteric Transition in the C-Terminal Domain of Calmodulin from Nuclear Magnetic Resonance Measurements.

PubMed

Kukic, Predrag; Lundström, Patrik; Camilloni, Carlo; Evenäs, Johan; Akke, Mikael; Vendruscolo, Michele

2016-01-12

Calmodulin is a two-domain signaling protein that becomes activated upon binding cooperatively two pairs of calcium ions, leading to large-scale conformational changes that expose its binding site. Despite significant advances in understanding the structural biology of calmodulin functions, the mechanistic details of the conformational transition between closed and open states have remained unclear. To investigate this transition, we used a combination of molecular dynamics simulations and nuclear magnetic resonance (NMR) experiments on the Ca(2+)-saturated E140Q C-terminal domain variant. Using chemical shift restraints in replica-averaged metadynamics simulations, we obtained a high-resolution structural ensemble consisting of two conformational states and validated such an ensemble against three independent experimental data sets, namely, interproton nuclear Overhauser enhancements, (15)N order parameters, and chemical shift differences between the exchanging states. Through a detailed analysis of this structural ensemble and of the corresponding statistical weights, we characterized a calcium-mediated conformational transition whereby the coordination of Ca(2+) by just one oxygen of the bidentate ligand E140 triggers a concerted movement of the two EF-hands that exposes the target binding site. This analysis provides atomistic insights into a possible Ca(2+)-mediated activation mechanism of calmodulin that cannot be achieved from static structures alone or from ensemble NMR measurements of the transition between conformations.

13C nuclear magnetic resonance and gas chromatography-mass spectrometry studies of carbon metabolism in the actinomycin D producer Streptomyces parvulus by use of 13C-labeled precursors.

PubMed Central

Inbar, L; Lapidot, A

1991-01-01

Fructose and glutamate metabolism was monitored in cell suspensions of streptomyces parvulus by 13C nuclear magnetic resonance. The experiments were performed for cells grown with various 13C sources in a growth medium containing D-[U-13C]fructose, L-[13C]glutamate, or L-[U-13C]aspartate and with nonlabeled precursors to compare intracellular pools in S. parvulus cells at different periods of the cell life cycle. The transport of fructose into the cells was biphasic in nature; during rapid transport, mannitol, fructose, and glucose 6-phosphate were accumulated intracellularly, whereas during the passive diffusion of fructose, the intracellular carbohydrate pool comprised mainly trehalose (1,1'-alpha-alpha-D-glucose). The regulation of fructokinase activity by the intracellular intermediates may play an important role in fructose catabolism in S. parvulus. Transaldolase activity in S. parvulus was determined from the 13C nuclear magnetic resonance labeling pattern of trehalose carbons obtained from cells grown in medium containing either L-[U-13C]aspartate or L-[U-13C]glutamate. Only carbons 4, 5, and 6 of the disaccharide were labeled. Isotopomer analysis of the trehalose carbons led us to conclude that the flux through the reverse glycolytic pathway, condensation of glyceraldehyde 3-phosphate with dihydroxyacetone phosphate, makes at best a minor contribution to the 13C-labeled glucose units observed in trehalose. The pentose pathway and transaldolase activity can explain the labeling pattern of 4,5,6-13C3 of trehalose. Moreover, the transfer of the 13C label of L-[U-13C]aspartate into the different isotopomers of trehalose C4, C5, and C6 by the transaldolase activity allowed us to calculate the relative fluxes from oxaloacetate via gluconeogenesis and through the tricarboxylic acid cycle. The ratio of the two fluxes is approximately 1. However, the main carbon source for trehalose synthesis in S. parvulus is fructose and not glutamate or aspartate. The 13C enrichment and isotopomer population, measured by nuclear magnetic resonance and gas chromatography-mass spectrometry, of the actinomycin D peptide ring enabled us to specify the origins of the five amino acids of actinomycin D. Threonine and proline exhibited isotopomer populations similar to that of the extracellular L-[13C]glutamate, indicating that protein catabolism is the origin of their 13C label, whereas the isotopomer populations of sarcosine and N-methylvaline were similar to those of the new intracellular pool of S. parvulus that originated from D-[U-13C]fructose during the production of actinomycin D. PMID:1744035

Francis bitter national magnet laboratory annual report, July 1991 through June 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-06-01

;Contents: Reports on Laboratory Research Programs--Magneto-Optics and Semiconductor Physics, Superconductivity and Magnetism, Solid State Nuclear Magnetic Resonance, Condensed Matter Chemistry, Biomagnetism, Magnet Technology, Instrumentation, Molecular Biophysics, Carbon Filters and Fullerenes; Reports of Visiting Scientists--Reports of Users of the High Magnetic Field Facility, Reports of the Users of the Pulsed Field Facility, Reports of the Users of the High Field NMR Facility; Appendices--Publications and Meeting Speeches, Organization, Summary of High Magnetic Field Facility Use--January 1, 1984 through June 30, 1992, Geographic Distribution of High Magnetic Field Facility Users (Excluding FBNML Staff), Summary of Educational Activities.

Francis Bitter National Magnet Laboratory annual report, July 1990 through June 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-06-01

The contents include: reports on laboratory research programs--magneto-optics and semiconductor physics, magnetism, superconductivity, solid state nuclear magnetic resonance, condensed matter chemistry, biomagnetism, magnet technology, instrumentation, molecular biophysics; reports of visiting scientists--reports of users of the high magnetic field facility, reports of users of the pulsed field facility, reports of users of the SQUID magnetometer and Mossbauer facility, reports of users of the high field NMR facility; appendices--publications and meeting speeches, organization, summary of high magnetic field facility use, user tables, geographic distribution of high magnetic field facility users, summary of educational activities.

Francis Bitter National Magnet Laboratory annual report, July 1989 through June 1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-01-01

Contents: Reports on laboratory research programs: Magneto-optics and semiconductor physics, Magnetism, Superconductivity, Solid state nuclear magnetic resonance, Condensed matter chemistry, Biomagnetism, Magnet technology, Molecular biophysics; Reports of visiting scientists: Reports of users of the High Magnetic Field Facility, Reports of users of the pulsed field facility, Reports of users of the squid magnetometer and Mossbauer facility, Reports of users of the high field NMR facility; Appendices: Publications and meeting speeches, Organization, Summary of high magnetic field facility use, User tables, Geographic distribution of high magnetic field facility users, Summary of educational activities.

Development of Millimeter Wave Fabry-Pérot Resonator for Simultaneous Electron-Spin and Nuclear Magnetic Resonance Measurement

NASA Astrophysics Data System (ADS)

Ishikawa, Yuya; Ohya, Kenta; Fujii, Yutaka; Fukuda, Akira; Miura, Shunsuke; Mitsudo, Seitaro; Yamamori, Hidetomo; Kikuchi, Hikomitsu

2018-04-01

We report a Fabry-Pérot resonator with spherical and flat mirrors to allow simultaneous electron-spin resonance (ESR) and nuclear magnetic resonance (NMR) measurements that could be used for double magnetic resonance (DoMR). In order to perform simultaneous ESR and NMR measurements, the flat mirror must reflect millimeter wavelength electromagnetic waves and the resonator must have a high Q value ( Q > 3000) for ESR frequencies, while the mirror must simultaneously let NMR frequencies pass through. This requirement can be achieved by exploiting the difference of skin depth for the two frequencies, since skin depth is inversely proportional to the square root of the frequency. In consideration of the skin depth, the optimum conditions for conducting ESR and NMR using a gold thin film are explored by examining the relation between the Q value and the film thickness. A flat mirror with a gold thin film was fabricated by sputtering gold on an epoxy plate. We also installed a Helmholtz radio frequency coil for NMR and tested the system both at room and low temperatures with an optimally thick gold film. As a result, signals were obtained at 0.18 K for ESR and at 1.3 K for NMR. A flat-mirrored resonator with a thin gold film surface is an effective way to locate NMR coils closer to the sample being examined with DoMR.

Detection of tannins in modern and fossil barks and in plant residues by high-resolution solid-state 13C nuclear magnetic resonance

USGS Publications Warehouse

Wilson, M.A.; Hatcher, P.G.

1988-01-01

Bark samples isolated from brown coal deposits in Victoria, Australia, and buried wood from Rhizophora mangle have been studies by high-resolution solid-state nuclear magnetic resonance (NMR) techniques. Dipolar dephasing 13C NMR appears to be a useful method of detecting the presence of tannins in geochemical samples including barks, buried woods, peats and leaf litter. It is shown that tannins are selectively preserved in bark during coalification to the brown coal stage. ?? 1988.

Direct monitoring by carbon-13 nuclear magnetic resonance spectroscopy of the metabolism and metabolic rate of 13C-labeled compounds in vivo.

PubMed

Iida, K; Hidoh, O; Fukami, J; Kajiwara, M

1991-01-01

Carbon-13 nuclear magnetic resonance spectroscopy has been used to observe the transformations of [1-13C]-D-glucose to [1,1'-13C2]-D-trehalose, and [3-13C]-L-alanine to [2-13C]-L-glutamic acid in the living body of Gryllodes sigillatus. [3-13C]-D-Alanine was not metabolized. The metabolic rate of [1-13C]-D-glucose was found to be altered by prior injection of boric acid.

Implementation of Quantum Private Queries Using Nuclear Magnetic Resonance

NASA Astrophysics Data System (ADS)

Wang, Chuan; Hao, Liang; Zhao, Lian-Jie

2011-08-01

We present a modified protocol for the realization of a quantum private query process on a classical database. Using one-qubit query and CNOT operation, the query process can be realized in a two-mode database. In the query process, the data privacy is preserved as the sender would not reveal any information about the database besides her query information, and the database provider cannot retain any information about the query. We implement the quantum private query protocol in a nuclear magnetic resonance system. The density matrix of the memory registers are constructed.

A potential nuclear magnetic resonance imaging approach for noncontact temperature measurement

NASA Technical Reports Server (NTRS)

Manatt, Stanley L.

1989-01-01

It is proposed that in a nuclear magnetic resonance (NMR) imaging experiment that it should be possible to measure temperature through an extended volume. The basis for such a measurement would depend upon sensing a temperature dependent on NMR parameter in an inert, volatile molecule (or fluid) filling the volume of interest. Exploratory work suggest that one suitable candidate for such a purpose might be CH3Cl. Possible parameters, other inert gases and feasible measurement schemes that might provide such temperature measurement are discussed.

A versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy.

NASA Technical Reports Server (NTRS)

Tarr, C. E.; Nickerson, M. A.

1972-01-01

A digital pulse programmer producing the standard pulse sequences required for pulsed nuclear magnetic resonance spectroscopy is described. In addition, a 'saturation burst' sequence, useful in the measurement of long relaxation times in solids, is provided. Both positive and negative 4 V trigger pulses are produced that are fully synchronous with a crystal-controlled time base, and the pulse programmer may be phase-locked with a maximum pulse jitter of 3 ns to the oscillator of a coherent pulse spectrometer. Medium speed TTL integrated circuits are used throughout.

Nuclear magnetic resonance diagnosis of an anaplastic astrocytoma.

PubMed

Jackson, J A; Derman, H S; Harper, R L; Willcott, M R; Ford, J J; Schneiders, N J; McCrary, J A; Kelly, A; Bryan, R N

1984-01-01

A patient presented with an 8-month history of a progressive left homonymous visual field deficit, left hemiparesis, and a left thalamocortical sensory deficit that was not detectable by repeated conventional neurodiagnostic evaluations. Proton nuclear magnetic resonance (NMR) imaging revealed a right parietal lesion characterized by a prolonged T2 (spin-spin relaxation time). At surgery, the mass proved to be an anaplastic astrocytoma. NMR appears to be more sensitive than x-ray computerized tomography scanning in some patients with malignant gliomas and offers the clinician an additional probe with which to evaluate these patients.

Proton electron nuclear double resonance from nitrosyl horse heart myoglobin: the role of His-E7 and Val-E11.

PubMed Central

Flores, M; Wajnberg, E; Bemski, G

2000-01-01

Electron nuclear double resonance (ENDOR) spectroscopy has been used to study protons in nitrosyl horse heart myoglobin (MbNO). (1)H ENDOR spectra were recorded for different settings of the magnetic field. Detailed analysis of the ENDOR powder spectra, using computer simulation, based on the "orientation-selection" principle, leads to the identification of the available protons in the heme pocket. We observe hyperfine interactions of the N(HisF8)-Fe(2+)-N(NO) complex with five protons in axial and with eight protons in the rhombic symmetry along different orientations, including those of the principal axes of the g-tensor. Protons from His-E7 and Val-E11 residues are identified in the two symmetries, rhombic and axial, exhibited by MbNO. Our results indicate that both residues are present inside the heme pocket and help to stabilize one particular conformation. PMID:10733988

Optimization of 13C dynamic nuclear polarization: isotopic labeling of free radicals

NASA Astrophysics Data System (ADS)

Niedbalski, Peter; Parish, Christopher; Kiswandi, Andhika; Lumata, Lloyd

Dynamic nuclear polarization (DNP) is a physics technique that amplifies the nuclear magnetic resonance (NMR) signals by transferring the high polarization of the electrons to the nuclear spins. Thus, the choice of free radical is crucial in DNP as it can directly affect the NMR signal enhancement levels, typically on the order of several thousand-fold in the liquid-state. In this study, we have investigated the efficiency of four variants of the well-known 4-oxo-TEMPO radical (normal 4-oxo-TEMPO plus its 15N-enriched and/or perdeuterated variants) for use in DNP of an important metabolic tracer [1-13C]acetate. Though the variants have significant differences in electron paramagnetic resonance (EPR) spectra, we have found that changing the composition of the TEMPO radical through deuteration or 15N doping yields no significant difference in 13C DNP efficiency at 3.35 T and 1.2 K. On the other hand, deuteration of the solvent causes a significant increase of 13C polarization that is consistent over all the 4-oxo-TEMPO variants. These findings are consistent with the thermal mixing model of DNP. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and the Robert A. Welch Foundation Grant No. AT-1877.

Nuclear Spin Locking and Extended Two-Electron Spin Decoherence Time in an InAs Quantum Dot Molecule

NASA Astrophysics Data System (ADS)

Chow, Colin; Ross, Aaron; Steel, Duncan; Sham, L. J.; Bracker, Allan; Gammon, Daniel

2015-03-01

The spin eigenstates for two electrons confined in a self-assembled InAs quantum dot molecule (QDM) consist of the spin singlet state, S, with J = 0 and the triplet states T-, T0 and T+, with J = 1. When a transverse magnetic field (Voigt geometry) is applied, the two-electron system can be initialized to the different states with appropriate laser excitation. Under the excitation of a weak probe laser, non-Lorentzian lineshapes are obtained when the system is initialized to either T- or T+, where T- results in a ``resonance locking'' lineshape while T+ gives a ``resonance avoiding '' lineshape: two different manifestations of hysteresis showing the importance of memory in the system. These observations signify dynamic nuclear spin polarization (DNSP) arising from a feedback mechanism involving hyperfine interaction between lattice nuclei and delocalized electron spins, and Overhauser shift due to nuclear spin polarization. Using pump configurations that generate coherent population trapping, the isolation of the electron spin from the optical excitation shows the stabilization of the nuclear spin ensemble. The dark-state lineshape measures the lengthened electron spin decoherence time, from 1 ns to 1 μs. Our detailed spectra highlight the potential of QDM for realizing a two-qubit gate. This work is supported by NSF, ARO, AFOSR, DARPA, and ONR.

Dynamic nuclear polarization using frequency modulation at 3.34 T.

PubMed

Hovav, Y; Feintuch, A; Vega, S; Goldfarb, D

2014-01-01

During dynamic nuclear polarization (DNP) experiments polarization is transferred from unpaired electrons to their neighboring nuclear spins, resulting in dramatic enhancement of the NMR signals. While in most cases this is achieved by continuous wave (cw) irradiation applied to samples in fixed external magnetic fields, here we show that DNP enhancement of static samples can improve by modulating the microwave (MW) frequency at a constant field of 3.34 T. The efficiency of triangular shaped modulation is explored by monitoring the (1)H signal enhancement in frozen solutions containing different TEMPOL radical concentrations at different temperatures. The optimal modulation parameters are examined experimentally and under the most favorable conditions a threefold enhancement is obtained with respect to constant frequency DNP in samples with low radical concentrations. The results are interpreted using numerical simulations on small spin systems. In particular, it is shown experimentally and explained theoretically that: (i) The optimal modulation frequency is higher than the electron spin-lattice relaxation rate. (ii) The optimal modulation amplitude must be smaller than the nuclear Larmor frequency and the EPR line-width, as expected. (iii) The MW frequencies corresponding to the enhancement maxima and minima are shifted away from one another when using frequency modulation, relative to the constant frequency experiments. Copyright © 2013 Elsevier Inc. All rights reserved.

Low-temperature nuclear magnetic resonance investigation of systems frustrated by competing exchange interactions

NASA Astrophysics Data System (ADS)

Roy, Beas

This doctoral thesis emphasizes on the study of frustrated systems which form a very interesting class of compounds in physics. The technique used for the investigation of the magnetic properties of the frustrated materials is Nuclear Magnetic Resonance (NMR). NMR is a very novel tool for the microscopic study of the spin systems. NMR enables us to investigate the local magnetic properties of any system exclusively. The NMR experiments on the different systems yield us knowledge of the static as well as the dynamic behavior of the electronic spins. Frustrated systems bear great possibilities of revelation of new physics through the new ground states they exhibit. The vandates AA'VO(PO4)2 [AA' ≡ Zn2 and BaCd] are great prototypes of the J1-J2 model which consists of magnetic ions sitting on the corners of a square lattice. Frustration is caused by the competing nearest-neighbor (NN) and next-nearest neighbor (NNN) exchange interactions. The NMR investigation concludes a columnar antiferromagnetic (AFM) state for both the compounds from the sharp peak of the nuclear spin-lattice relaxation rate (1/T1) and a sudden broadening of the 31P-NMR spectrum. The important conclusion from our study is the establishment of the first H-P-T phase diagram of BaCdVO(PO4)2. Application of high pressure reduces the saturation field (HS) in BaCdVO(PO4)2 and decreases the ratio J2/J1, pushing the system more towards a questionable boundary (a disordered ground state) between the columnar AFM and a ferromagnetic ground state. A pressure up to 2.4 GPa will completely suppress HS. The Fe ions in the `122' iron-arsenide superconductors also sit on a square lattice thus closely resembling the J1-J2 model. The 75As-NMR and Nuclear Quadrupole Resonance (NQR) experiments are conducted in the compound CaFe2As2 prepared by two different heat treatment methods (`as-grown' and `annealed'). Interestingly the two samples show two different ground states. While the ground state of the `as-grown' sample shows a non-magnetic collapsed tetragonal phase (with no magnetic fluctuations), the ground state of the `annealed' sample shows a magnetically long-range ordered orthorhombic phase. The temperature dependence of 1/T1 and that of Knight shift showed that the electron correlations completely disappear in the nonsuperconducting collapsed tetragonal phase in `as-grown' sample of CaFe2As2 indicating quenching of Fe moments. The insulating A-site spinel compound CoAl2O4 exhibits frustration due to competing NN and NNN exchange interactions. This compound has been studied for a long time yet there has been a contradiction as to what the ground state of this compound is. The origin of this ambiguity was pointed out to be microstructure effects such as site-inversion between Co and Al. Thus depending on the value of degree of site inversion x [(Co{1-x}Alx)[Al{2-x}Cox]O4], the ground states differ. A very high quality sample was prepared (x ≈ 0.06) and 27Al and 59Co NMR were performed to study the ground state of this compound. Together with the results from heat capacity, magnetic measurements and neutron diffraction measurements we conclude that the ground state is collinear AFM. We settled a long debated problem for the ground state of CoAl2O4. The compound BiMn2PO6 is a magnetically frustrated system with three-dimensional magnetic ordering. Frustration in this compound is caused by the comparable values of the exchange interactions along the chain, along the rung and in between the ladders. Thus the magnetic structure of this compound is quite complex with the temperature dependence of magnetic susceptibility exhibiting peak at 30 K, a jump at 43 K and a change of slope at 10 K. 31P-NMR study was done on this system to investigate the nature of transitions (if any) at these temperatures. NMR study suggested a long-range AFM transition at 30 K with a sharp peak in 1/T1. No signature of transition at 43 K suggested its origin is extrinsic. Between 10 K and 30 K the NMR spectra proved the existence of a commensurate magnetic order while below 10 K, the shape of the NMR spectrum changes either due to an incommensurate magnetic order or due to spin reorientation. In summary the work presented in this thesis focusses on the NMR investigation of the magnetic properties of various compounds frustrated by the competing exchange interactions. References. [1] A. Yogi, N. Ahmad, R. Nath, A. A. Tsirlin, J. Sichelschmidt, B. Roy and Y. Furukawa, arXiv:1409.3076 (submitted to Phys. Rev. B). [2] Beas Roy, Yuji Furukawa, Ramesh Nath, David C. Johnston, J. Phys.: Conf. Ser. 320, 012048 (2011). [3] Beas Roy, Yuji Furukawa, David Johnston, Ramesh Nath, Yasuhiro Komaki, Hideto Fukazawa, and Yoh Kohori, ``Magnetic phase diagram of the two-dimensional frustrated square lattice compound BaCdVO(PO4)2 from high-pressure and low-temperature 31P-NMR study'', Paper to be submitted. [4] S. Ran, S. L. Bud'ko, D. K. Pratt, A. Kreyssig, M. G. Kim, M. J. Kramer, D. H. Ryan, W. N. Rowan-Weetaluktuk, Y. Furukawa, B. Roy, A. I. Goldman, and P. C. Canfield, Phys. Rev. B 83, 144517 (2011). [5] Y. Furukawa, B. Roy, S. Ran, S. L. Bud'ko and P. C. Canfield, Phys. Rev. B 89, 121109 (R) (2014). [6] B. Roy, Abhishek Pandey, Q. Zhang, T. W. Heitmann, D. Vaknin, D. C. Johnston, and Y. Furukawa, Phys. Rev. B 88, 174415 (2013). [7] R. Nath, K. M. Ranjith, B. Roy, D. C. Johnston, Y. Furukawa, and A. A. Tsirlin, Phys. Rev. B 90, 024431 (2014).

Spin-orbit ZORA and four-component Dirac-Coulomb estimation of relativistic corrections to isotropic nuclear shieldings and chemical shifts of noble gas dimers.

PubMed

Jankowska, Marzena; Kupka, Teobald; Stobiński, Leszek; Faber, Rasmus; Lacerda, Evanildo G; Sauer, Stephan P A

2016-02-05

Hartree-Fock and density functional theory with the hybrid B3LYP and general gradient KT2 exchange-correlation functionals were used for nonrelativistic and relativistic nuclear magnetic shielding calculations of helium, neon, argon, krypton, and xenon dimers and free atoms. Relativistic corrections were calculated with the scalar and spin-orbit zeroth-order regular approximation Hamiltonian in combination with the large Slater-type basis set QZ4P as well as with the four-component Dirac-Coulomb Hamiltonian using Dyall's acv4z basis sets. The relativistic corrections to the nuclear magnetic shieldings and chemical shifts are combined with nonrelativistic coupled cluster singles and doubles with noniterative triple excitations [CCSD(T)] calculations using the very large polarization-consistent basis sets aug-pcSseg-4 for He, Ne and Ar, aug-pcSseg-3 for Kr, and the AQZP basis set for Xe. For the dimers also, zero-point vibrational (ZPV) corrections are obtained at the CCSD(T) level with the same basis sets were added. Best estimates of the dimer chemical shifts are generated from these nuclear magnetic shieldings and the relative importance of electron correlation, ZPV, and relativistic corrections for the shieldings and chemical shifts is analyzed. © 2015 Wiley Periodicals, Inc.

Construction and 13C NMR signal-amplification efficiency of a dynamic nuclear polarizer at 6.4 T and 1.4 K

NASA Astrophysics Data System (ADS)

Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Ferguson, Sarah; Taylor, David; McDonald, George; Lumata, Lloyd

Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging technique in biomedical and metabolic imaging since it amplifies the liquid-state nuclear magnetic resonance (NMR) and imaging (MRI) signals by >10,000-fold. Originally used in nuclear scattering experiments, DNP works by creating a non-Boltzmann nuclear spin distribution by transferring the high electron (γ = 28,000 MHz/T) thermal polarization to the nuclear spins via microwave irradiation of the sample at high magnetic field and low temperature. A dissolution device is used to rapidly dissolve the frozen sample and consequently produces an injectable ``hyperpolarized'' liquid at physiologically-tolerable temperature. Here we report the construction and performance evaluation of a dissolution DNP hyperpolarizer at 6.4 T and 1.4 K using a continuous-flow cryostat. The solid and liquid-state 13C NMR signal enhancement levels of 13C acetate samples doped with trityl OX063 and 4-oxo-TEMPO free radicals will be discussed and compared with the results from the 3.35 T commercial hyperpolarizer. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

Solution nuclear magnetic resonance spectroscopy on a nanostructured diamond chip.

PubMed

Kehayias, P; Jarmola, A; Mosavian, N; Fescenko, I; Benito, F M; Laraoui, A; Smits, J; Bougas, L; Budker, D; Neumann, A; Brueck, S R J; Acosta, V M

2017-08-04

Sensors using nitrogen-vacancy centers in diamond are a promising tool for small-volume nuclear magnetic resonance (NMR) spectroscopy, but the limited sensitivity remains a challenge. Here we show nearly two orders of magnitude improvement in concentration sensitivity over previous nitrogen-vacancy and picoliter NMR studies. We demonstrate NMR spectroscopy of picoliter-volume solutions using a nanostructured diamond chip with dense, high-aspect-ratio nanogratings, enhancing the surface area by 15 times. The nanograting sidewalls are doped with nitrogen-vacancies located a few nanometers from the diamond surface to detect the NMR spectrum of roughly 1 pl of fluid lying within adjacent nanograting grooves. We perform 1 H and 19 F nuclear magnetic resonance spectroscopy at room temperature in magnetic fields below 50 mT. Using a solution of CsF in glycerol, we determine that 4 ± 2 × 10 12 19 F spins in a 1 pl volume can be detected with a signal-to-noise ratio of 3 in 1 s of integration.Nitrogen vacancy (NV) centres in diamond can be used for NMR spectroscopy, but increased sensitivity is needed to avoid long measurement times. Kehayias et al. present a nanostructured diamond grating with a high density of NV centres, enabling NMR spectroscopy of picoliter-volume solutions.

Assembly and performance of a 6.4 T cryogen-free dynamic nuclear polarization system.

PubMed

Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Wang, Qing; Lumata, Lloyd

2017-09-01

We report on the assembly and performance evaluation of a 180-GHz/6.4 T dynamic nuclear polarization (DNP) system based on a cryogen-free superconducting magnet. The DNP system utilizes a variable-field superconducting magnet that can be ramped up to 9 T and equipped with cryocoolers that can cool the sample space with the DNP assembly down to 1.8 K via the Joule-Thomson effect. A homebuilt DNP probe insert with top-tuned nuclear magnetic resonance coil and microwave port was incorporated into the sample space in which the effective sample temperature is approximately 1.9 K when a 180-GHz microwave source is on during DNP operation. 13 C DNP of [1- 13 C] acetate samples doped with trityl OX063 and 4-oxo-TEMPO in this system have resulted in solid-state 13 C polarization levels of 58 ± 3% and 18 ± 2%, respectively. The relatively high 13 C polarization levels achieved in this work have demonstrated that the use of a cryogen-free superconducting magnet for 13 C DNP is feasible and in fact, relatively efficient-a major leap to offset the high cost of liquid helium consumption in DNP experiments. Copyright © 2017 John Wiley & Sons, Ltd.

Design and expected performance of a compact and continuous nuclear demagnetization refrigerator for sub-mK applications

NASA Astrophysics Data System (ADS)

Toda, Ryo; Murakawa, Satoshi; Fukuyama, Hiroshi

2018-03-01

Sub-mK temperatures are achievable by a copper nuclear demagnetization refrigerator (NDR). Recently, research demands for such an ultra-low temperature environment are increasing not only in condensed matter physics but also in astrophysics. A standard NDR requires a specially designed room, a high-field superconducting magnet, and a high-power dilution refrigerator (DR). And it is a one-shot cooling apparatus. To reduce these requirements, we are developing a compact and continuous NDR with two PrNi5 nuclear stages which occupies only a small space next to an appropriate pre-cooling stage such as DR. PrNi5 has a large magnetic-field enhancement on Pr3+ nuclei due to the strong hyperfine coupling. This enables us to enclose each stage in a miniature superconducting magnet and to locate two such sets in close proximity by surrounding them with high-permeability magnetic shields. The two stages are thermally connected in series to the pre-cooling stage by two Zn superconducting heat switches. A numerical analysis taking account of thermal resistances of all parts and an eddy current heating shows that the lowest sample temperature of 0.8 mK can be maintained continuously under a 10 nW ambient heat leak.

Novel scintillators and silicon photomultipliers for nuclear physics and applications

NASA Astrophysics Data System (ADS)

Jenkins, David

2015-06-01

Until comparatively recently, scintillator detectors were seen as an old-fashioned tool of nuclear physics with more attention being given to areas such as gamma-ray tracking using high-purity germanium detectors. Next-generation scintillator detectors, such as lanthanum bromide, which were developed for the demands of space science and gamma- ray telescopes, are found to have strong applicability to low energy nuclear physics. Their excellent timing resolution makes them very suitable for fast timing measurements and their much improved energy resolution compared to conventional scintillators promises to open up new avenues in nuclear physics research which were presently hard to access. Such "medium-resolution" spectroscopy has broad interest across several areas of contemporary interest such as the study of nuclear giant resonances. In addition to the connections to space science, it is striking that the demands of contemporary medical imaging have strong overlap with those of experimental nuclear physics. An example is the interest in PET-MRI combined imaging which requires putting scintillator detectors in a high magnetic field environment. This has led to strong advances in the area of silicon photomultipliers, a solid-state replacement for photomultiplier tubes, which are insensitive to magnetic fields. Broad application to nuclear physics of this technology may be foreseen.

Evidence of solvent-gelator interaction in sugar-based organogel studied by field-cycling NMR relaxometry.

PubMed

Bielejewski, Michal; Tritt-Goc, Jadwiga

2010-11-16

The dynamics of bulk toluene and toluene confined in the 1,2-O-(1-ethylpropylidene)-α-D-glucofuranose gel was studied using (1)H field-cycling nuclear magnetic resonance relaxometry. The proton spin-lattice relaxation time T(1) was measured as a function of the magnetic field strength and temperature. The observed dispersion in the frequency range 10(4)-10(6) Hz for the relaxation rate of toluene in the gel system give evidence of the interaction between the toluene and the gelator aggregates. The data were interpreted in terms of the two-fraction fast-exchange model. Additionally it was also shown that a cooling rate during gel preparation process influences the gel microstructure and leads to different gelator-solvent interactions as reflected in a different behavior of the proton spin-lattice relaxation rate of toluene within the gel observed at the low frequency range.

Redox-dependent structure change and hyperfine nuclear magnetic resonance shifts in cytochrome c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Yiquing; Roder, H.; Englander, S.W.

1990-04-10

Proton nuclear magnetic resonance assignments for reduced and oxidized equine cytochrome c show that many individual protons exhibit different chemical shifts in the two protein forms, reflecting diamagnetic shift effects due to structure change, and in addition contact and pseudocontact shifts that occur only in the paramagnetic oxidized form. To evaluate the chemical shift differences for structure change, the authors removed the pseudocontact shift contribution by a calculation based on knowledge of the electron spin g tensor. The g-tensor calculation, when repeated using only 12 available C{sub {alpha}}H proton resonances for cytochrom c from tuna, proved to be remarkably stable.more » The derived g tensor was then used together with spatial coordinates for the oxidized form to calculate the pseudocontact shift contribution to proton resonances at 400 identifiable sites throughout the protein, so that the redox-dependent chemical shift discrepancy, could be evaluated. Large residual changes in chemical shift define the Fermi contact shifts, where are found as expected to be limited to the immediate covalent structure of the heme and its ligands and to be asymmetrically distributed over the heme. The chemical shift discrepancies observed appear in the main to reflect structure-dependent diamagnetic shifts rather than hyperfine effects due to displacements in the pseudocontact shift field. Although 51 protons in 29 different residues exhibit significant chemical shift changes, the general impressions one of small structural adjustments to redox-dependent strain rather than sizeable structural displacements or rearrangements.« less

Grade classification of neuroepithelial tumors using high-resolution magic-angle spinning proton nuclear magnetic resonance spectroscopy and pattern recognition.

PubMed

Chen, WenXue; Lou, HaiYan; Zhang, HongPing; Nie, Xiu; Lan, WenXian; Yang, YongXia; Xiang, Yun; Qi, JianPin; Lei, Hao; Tang, HuiRu; Chen, FenEr; Deng, Feng

2011-07-01

Clinical data have shown that survival rates vary considerably among brain tumor patients, according to the type and grade of the tumor. Metabolite profiles of intact tumor tissues measured with high-resolution magic-angle spinning proton nuclear magnetic resonance spectroscopy (HRMAS (1)H NMRS) can provide important information on tumor biology and metabolism. These metabolic fingerprints can then be used for tumor classification and grading, with great potential value for tumor diagnosis. We studied the metabolic characteristics of 30 neuroepithelial tumor biopsies, including two astrocytomas (grade I), 12 astrocytomas (grade II), eight anaplastic astrocytomas (grade III), three glioblastomas (grade IV) and five medulloblastomas (grade IV) from 30 patients using HRMAS (1)H NMRS. The results were correlated with pathological features using multivariate data analysis, including principal component analysis (PCA). There were significant differences in the levels of N-acetyl-aspartate (NAA), creatine, myo-inositol, glycine and lactate between tumors of different grades (P<0.05). There were also significant differences in the ratios of NAA/creatine, lactate/creatine, myo-inositol/creatine, glycine/creatine, scyllo-inositol/creatine and alanine/creatine (P<0.05). A soft independent modeling of class analogy model produced a predictive accuracy of 87% for high-grade (grade III-IV) brain tumors with a sensitivity of 87% and a specificity of 93%. HRMAS (1)H NMR spectroscopy in conjunction with pattern recognition thus provides a potentially useful tool for the rapid and accurate classification of human brain tumor grades.

Profiling contents of water-soluble metabolites and mineral nutrients to evaluate the effects of pesticides and organic and chemical fertilizers on tomato fruit quality.

PubMed

Watanabe, Masami; Ohta, Yuko; Licang, Sun; Motoyama, Naoki; Kikuchi, Jun

2015-02-15

In this study, the contents of water-soluble metabolites and mineral nutrients were measured in tomatoes cultured using organic and chemical fertilizers, with or without pesticides. Mineral nutrients and water-soluble metabolites were determined by inductively coupled plasma-atomic emission spectrometry and (1)H nuclear magnetic resonance spectrometry, respectively, and results were analysed by principal components analysis (PCA). The mineral nutrient and water-soluble metabolite profiles differed between organic and chemical fertilizer applications, which accounted for 88.0% and 55.4%, respectively, of the variation. (1)H-(13)C-hetero-nuclear single quantum coherence experiments identified aliphatic protons that contributed to the discrimination of PCA. Pesticide application had little effect on mineral nutrient content (except Fe and P), but affected the correlation between mineral nutrients and metabolites. Differences in the content of mineral nutrients and water-soluble metabolites resulting from different fertilizer and pesticide applications probably affect tomato quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

NASA Astrophysics Data System (ADS)

Okuno, Yusuke; Cavagnero, Silvia

2018-01-01

Given its short hyperpolarization time (∼10-6 s) and mostly non-perturbative nature, photo-chemically induced dynamic nuclear polarization (photo-CIDNP) is a powerful tool for sensitivity enhancement in nuclear magnetic resonance. In this study, we explore the extent of 1H-detected 13C nuclear hyperpolarization that can be gained via photo-CIDNP in the presence of small-molecule additives containing a heavy atom. The underlying rationale for this methodology is the well-known external-heavy-atom (EHA) effect, which leads to significant enhancements in the intersystem-crossing rate of selected photosensitizer dyes from photoexcited singlet to triplet. We exploited the EHA effect upon addition of moderate amounts of halogen-atom-containing cosolutes. The resulting increase in the transient triplet-state population of the photo-CIDNP sensitizer fluorescein resulted in a significant increase in the nuclear hyperpolarization achievable via photo-CIDNP in liquids. We also explored the internal-heavy-atom (IHA) effect, which is mediated by halogen atoms covalently incorporated into the photosensitizer dye. Widely different outcomes were achieved in the case of EHA and IHA, with EHA being largely preferable in terms of net hyperpolarization.

High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yuqing; Cai, Shuhui; Yang, Yu

2016-03-14

High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this methodmore » are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.« less

Field-cycling NMR experiments in an ultra-wide magnetic field range: relaxation and coherent polarization transfer.

PubMed

Zhukov, Ivan V; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Grishin, Yuri A; Vieth, Hans-Martin; Ivanov, Konstantin L

2018-05-09

An experimental method is described allowing fast field-cycling Nuclear Magnetic Resonance (NMR) experiments over a wide range of magnetic fields from 5 nT to 10 T. The method makes use of a hybrid technique: the high field range is covered by positioning the sample in the inhomogeneous stray field of the NMR spectrometer magnet. For fields below 2 mT a magnetic shield is mounted on top of the spectrometer; inside the shield the magnetic field is controlled by a specially designed coil system. This combination allows us to measure T1-relaxation times and nuclear Overhauser effect parameters over the full range in a routine way. For coupled proton-carbon spin systems relaxation with a common T1 is found at low fields, where the spins are "strongly coupled". In some cases, experiments at ultralow fields provide access to heteronuclear long-lived spin states. Efficient coherent polarization transfer is seen for proton-carbon spin systems at ultralow fields as follows from the observation of quantum oscillations in the polarization evolution. Applications to analysis and the manipulation of heteronuclear spin systems are discussed.

Absence of 60-Hz, 0.1-mT magnetic field-induced changes in oncogene transcription rates or levels in CEM-CM3 cells.

PubMed

Jahreis, G P; Johnson, P G; Zhao, Y L; Hui, S W

1998-12-22

Our objective was to assess the reproducibility of the 60-Hz magnetic field-induced, time-dependent transcription changes of c-fos, c-jun and c-myc oncogenes in CEM-CM3 cells reported by Phillips et al. (Biochim. Biophys. Acta, 1132 (1992) 140-144). Cells were exposed to a 60-Hz magnetic field (MF) at 0.1 mT (rms), generated by a pair of Helmholtz coils energized in a reinforcing (MF) mode, or to a null magnetic field when the coils were energized in a bucking (sham) mode. After MF or sham exposure for 15, 30, 60 or 120 min, nuclei and cytoplasmic RNA were extracted. Transcription rates were measured by a nuclear run-on assay, and values were normalized against either their zero-time exposure values, or against those of the c-G3PDH (housekeeping) gene at the same time points. There was no significant difference, at P=0.05, detected between MF and either sham-exposed or control cells at any time point. Transcript levels of the oncogenes were measured by Northern analysis and normalized as above. No significant difference (P=0.05) in transcript levels between MF and either sham-exposed or control cells was detected.

Magnetic Imaging: a New Tool for UK National Nuclear Security

NASA Astrophysics Data System (ADS)

Darrer, Brendan J.; Watson, Joe C.; Bartlett, Paul; Renzoni, Ferruccio

2015-01-01

Combating illicit trafficking of Special Nuclear Material may require the ability to image through electromagnetic shields. This is the case when the trafficking involves cargo containers. Thus, suitable detection techniques are required to penetrate a ferromagnetic enclosure. The present study considers techniques that employ an electromagnetic based principle of detection. It is generally assumed that a ferromagnetic metallic enclosure will effectively act as a Faraday cage to electromagnetic radiation and therefore screen any form of interrogating electromagnetic radiation from penetrating, thus denying the detection of any eventual hidden material. In contrast, we demonstrate that it is actually possible to capture magnetic images of a conductive object through a set of metallic ferromagnetic enclosures. This validates electromagnetic interrogation techniques as a potential detection tool for National Nuclear Security applications.

Magnetic Imaging: a New Tool for UK National Nuclear Security

PubMed Central

Darrer, Brendan J.; Watson, Joe C.; Bartlett, Paul; Renzoni, Ferruccio

2015-01-01

Combating illicit trafficking of Special Nuclear Material may require the ability to image through electromagnetic shields. This is the case when the trafficking involves cargo containers. Thus, suitable detection techniques are required to penetrate a ferromagnetic enclosure. The present study considers techniques that employ an electromagnetic based principle of detection. It is generally assumed that a ferromagnetic metallic enclosure will effectively act as a Faraday cage to electromagnetic radiation and therefore screen any form of interrogating electromagnetic radiation from penetrating, thus denying the detection of any eventual hidden material. In contrast, we demonstrate that it is actually possible to capture magnetic images of a conductive object through a set of metallic ferromagnetic enclosures. This validates electromagnetic interrogation techniques as a potential detection tool for National Nuclear Security applications. PMID:25608957

Magnetic imaging: a new tool for UK national nuclear security.

PubMed

Darrer, Brendan J; Watson, Joe C; Bartlett, Paul; Renzoni, Ferruccio

2015-01-22

Combating illicit trafficking of Special Nuclear Material may require the ability to image through electromagnetic shields. This is the case when the trafficking involves cargo containers. Thus, suitable detection techniques are required to penetrate a ferromagnetic enclosure. The present study considers techniques that employ an electromagnetic based principle of detection. It is generally assumed that a ferromagnetic metallic enclosure will effectively act as a Faraday cage to electromagnetic radiation and therefore screen any form of interrogating electromagnetic radiation from penetrating, thus denying the detection of any eventual hidden material. In contrast, we demonstrate that it is actually possible to capture magnetic images of a conductive object through a set of metallic ferromagnetic enclosures. This validates electromagnetic interrogation techniques as a potential detection tool for National Nuclear Security applications.

Extending the electron spin coherence time of atomic hydrogen by dynamical decoupling.

PubMed

Mitrikas, George; Efthimiadou, Eleni K; Kordas, George

2014-02-14

We study the electron spin decoherence of encapsulated atomic hydrogen in octasilsesquioxane cages induced by the (1)H and (29)Si nuclear spin bath. By applying the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence we significantly suppress the low-frequency noise due to nuclear spin flip-flops up to the point where a maximum T2 = 56 μs is observed. Moreover, dynamical decoupling with the CPMG sequence reveals the existence of two other sources of decoherence: first, a classical magnetic field noise imposed by the (1)H nuclear spins of the cage organic substituents, which can be described by a virtual fluctuating magnetic field with the proton Larmor frequency, and second, decoherence due to anisotropic hyperfine coupling between the electron and the inner (29)Si spins of the cage.

10 CFR 1045.15 - Classification and declassification presumptions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... experimental physics, engineering, materials science, biology and medicine; (2) Magnetic confinement fusion... the application of the criteria in § 1045.16 indicates otherwise: (1) Detailed designs, specifications... design and analysis of nuclear weapons; (3) Vulnerabilities of U.S. nuclear weapons to sabotage...

10 CFR 1045.15 - Classification and declassification presumptions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... experimental physics, engineering, materials science, biology and medicine; (2) Magnetic confinement fusion... the application of the criteria in § 1045.16 indicates otherwise: (1) Detailed designs, specifications... design and analysis of nuclear weapons; (3) Vulnerabilities of U.S. nuclear weapons to sabotage...

Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: longitudinal relaxation dispersion for spin I = 1.

PubMed

Nilsson, Tomas; Halle, Bertil

2012-08-07

The frequency dependence of the longitudinal relaxation rate, known as the magnetic relaxation dispersion (MRD), can provide a frequency-resolved characterization of molecular motions in complex biological and colloidal systems on time scales ranging from 1 ns to 100 μs. The conformational dynamics of immobilized proteins and other biopolymers can thus be probed in vitro or in vivo by exploiting internal water molecules or labile hydrogens that exchange with a dominant bulk water pool. Numerous water (1)H and (2)H MRD studies of such systems have been reported, but the widely different theoretical models currently used to analyze the MRD data have resulted in divergent views of the underlying molecular motions. We have argued that the essential mechanism responsible for the main dispersion is the exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings when internal water molecules or labile hydrogens escape from orientationally confining macromolecular sites. In the EMOR model, the exchange process is thus not just a means of mixing spin populations but it is also the direct cause of spin relaxation. Although the EMOR theory has been used in several studies to analyze water (2)H MRD data from immobilized biopolymers, the fully developed theory has not been described. Here, we present a comprehensive account of a generalized version of the EMOR theory for spin I = 1 nuclides like (2)H. As compared to a previously described version of the EMOR theory, the present version incorporates three generalizations that are all essential in applications to experimental data: (i) a biaxial (residual) electric field gradient tensor, (ii) direct and indirect effects of internal motions, and (iii) multiple sites with different exchange rates. In addition, we describe and assess different approximations to the exact EMOR theory that are useful in various regimes. In particular, we consider the experimentally important dilute regime, for which approximate analytical results are derived. As shown by the analytical expressions, and confirmed by exact numerical calculations, the dispersion is governed by the pure nuclear quadrupole resonance frequencies in the ultraslow-motion regime, where the relaxation rate also exhibits a much stronger dependence on the electric field gradient asymmetry than in the motional-narrowing regime.

Thermally generated magnetic fields in laser-driven compressions and explosions

NASA Technical Reports Server (NTRS)

Tidman, D. A.

1975-01-01

The evolution of thermally generated magnetic fields in a plasma undergoing a nearly spherically symmetric adiabatic compression or expansion is calculated. The analysis is applied to obtain approximate results for the development of magnetic fields in laser-driven compression and explosion of a pellet of nuclear fuel. Localized sources, such as those occurring at composition boundaries in structured pellets or at shock fronts, give stronger fields than those deriving from smoothly distributed asymmetries. Although these fields may approach 10 million G in the late stages of compression, this is not expected to present difficulties for the compression process. Assuming ignition of a nuclear explosion occurs, the sources become much stronger, and values of approximately 10 billion G are obtained at tamper boundaries assuming a 20% departure from spherical symmetry during the explosion.

Communication: Heterogeneous water dynamics on a clathrate hydrate lattice detected by multidimensional oxygen nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Adjei-Acheamfour, Mischa; Storek, Michael; Böhmer, Roland

2017-05-01

Previous deuteron nuclear magnetic resonance studies revealed conflicting evidence regarding the possible motional heterogeneity of the water dynamics on the hydrate lattice of an ice-like crystal. Using oxygen-17 nuclei as a sensitive quadrupolar probe, the reorientational two-time correlation function displays a clear nonexponentiality. To check whether this dispersive behavior is a consequence of dynamic heterogeneity or rather of an intrinsic nonexponentiality, a multidimensional, four-time magnetic resonance experiment was devised that is generally applicable to strongly quadrupolarly perturbed half-integer nuclei such as oxygen-17. Measurements of an appropriate four-time function demonstrate that it is possible to select a subensemble of slow water molecules. Its mean time scale is compared to theoretical predictions and evidence for significant motional heterogeneity is found.

Wide-Angle X-Ray Scattering and Solid-State Nuclear Magnetic Resonance Data Combined to Test Models for Cellulose Microfibrils in Mung Bean Cell Walls1

PubMed Central

Newman, Roger H.; Hill, Stefan J.; Harris, Philip J.

2013-01-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette. PMID:24154621

Magnetic shield for turbomolecular pump of the Magnetized Plasma Linear Experimental device at Saha Institute of Nuclear Physics.

PubMed

Biswas, Subir; Chattopadhyay, Monobir; Pal, Rabindranath

2011-01-01

The turbo molecular pump of the Magnetized Plasma Linear Experimental device is protected from damage by a magnetic shield. As the pump runs continuously in a magnetic field environment during a plasma physics experiment, it may get damaged owing to eddy current effect. For design and testing of the shield, first we simulate in details various aspects of magnetic shield layouts using a readily available field design code. The performance of the shield made from two half cylinders of soft iron material, is experimentally observed to agree very well with the simulation results.

ADVANCED DESIGNS OF MAGNETIC JACK-TYPE CONTROL ROD DRIVE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, J.N.

1959-11-01

The magnetic jack is a device for positioning the control rods In a nuclear reactor, especially in a reactor containing water under pressure. Magnetic actuation precludes the need for shaft seals and eliminates the problems associated with mechanisms operating in water. It consists of a pressure shell, four sets of external stationary magnet coils (hold, grip, lift, pull down), and one Internal moving part (ammature) that impants linear motion to a cluster of rods. (W.L.H.)

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-06-29

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2009-11-10

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2007-12-11

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-07-13

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2009-10-27

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Stages of Adult Soft Tissue Sarcoma

MedlinePlus

... that uses a magnet, radio waves , and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). PET scan (positron emission tomography scan) : A procedure to find malignant tumor cells ...

Treatment Option Overview (Adult Soft Tissue Sarcoma)

MedlinePlus

... that uses a magnet, radio waves , and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). PET scan (positron emission tomography scan) : A procedure to find malignant tumor cells ...

Treatment Options for Adult Soft Tissue Sarcoma

MedlinePlus

... that uses a magnet, radio waves , and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). PET scan (positron emission tomography scan) : A procedure to find malignant tumor cells ...

Quantum simulations of nuclei and nuclear pasta with the multiresolution adaptive numerical environment for scientific simulations

NASA Astrophysics Data System (ADS)

Sagert, I.; Fann, G. I.; Fattoyev, F. J.; Postnikov, S.; Horowitz, C. J.

2016-05-01

Background: Neutron star and supernova matter at densities just below the nuclear matter saturation density is expected to form a lattice of exotic shapes. These so-called nuclear pasta phases are caused by Coulomb frustration. Their elastic and transport properties are believed to play an important role for thermal and magnetic field evolution, rotation, and oscillation of neutron stars. Furthermore, they can impact neutrino opacities in core-collapse supernovae. Purpose: In this work, we present proof-of-principle three-dimensional (3D) Skyrme Hartree-Fock (SHF) simulations of nuclear pasta with the Multi-resolution ADaptive Numerical Environment for Scientific Simulations (MADNESS). Methods: We perform benchmark studies of 16O, 208Pb, and 238U nuclear ground states and calculate binding energies via 3D SHF simulations. Results are compared with experimentally measured binding energies as well as with theoretically predicted values from an established SHF code. The nuclear pasta simulation is initialized in the so-called waffle geometry as obtained by the Indiana University Molecular Dynamics (IUMD) code. The size of the unit cell is 24 fm with an average density of about ρ =0.05 fm-3 , proton fraction of Yp=0.3 , and temperature of T =0 MeV. Results: Our calculations reproduce the binding energies and shapes of light and heavy nuclei with different geometries. For the pasta simulation, we find that the final geometry is very similar to the initial waffle state. We compare calculations with and without spin-orbit forces. We find that while subtle differences are present, the pasta phase remains in the waffle geometry. Conclusions: Within the MADNESS framework, we can successfully perform calculations of inhomogeneous nuclear matter. By using pasta configurations from IUMD it is possible to explore different geometries and test the impact of self-consistent calculations on the latter.

Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

DOE PAGES

Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; ...

2015-10-20

In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

A simple hand-held magnet array for efficient and reproducible SABRE hyperpolarisation using manual sample shaking.

PubMed

Richardson, Peter M; Jackson, Scott; Parrott, Andrew J; Nordon, Alison; Duckett, Simon B; Halse, Meghan E

2018-07-01

Signal amplification by reversible exchange (SABRE) is a hyperpolarisation technique that catalytically transfers nuclear polarisation from parahydrogen, the singlet nuclear isomer of H 2 , to a substrate in solution. The SABRE exchange reaction is carried out in a polarisation transfer field (PTF) of tens of gauss before transfer to a stronger magnetic field for nuclear magnetic resonance (NMR) detection. In the simplest implementation, polarisation transfer is achieved by shaking the sample in the stray field of a superconducting NMR magnet. Although convenient, this method suffers from limited reproducibility and cannot be used with NMR spectrometers that do not have appreciable stray fields, such as benchtop instruments. Here, we use a simple hand-held permanent magnet array to provide the necessary PTF during sample shaking. We find that the use of this array provides a 25% increase in SABRE enhancement over the stray field approach, while also providing improved reproducibility. Arrays with a range of PTFs were tested, and the PTF-dependent SABRE enhancements were found to be in excellent agreement with comparable experiments carried out using an automated flow system where an electromagnet is used to generate the PTF. We anticipate that this approach will improve the efficiency and reproducibility of SABRE experiments carried out using manual shaking and will be particularly useful for benchtop NMR, where a suitable stray field is not readily accessible. The ability to construct arrays with a range of PTFs will also enable the rapid optimisation of SABRE enhancement as function of PTF for new substrate and catalyst systems. © 2017 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons Ltd.

Comparative analyses of studies of childhood leukemia and magnetic fields, radon and gamma radiation.

PubMed

Kheifets, Leeka; Swanson, John; Yuan, Yingzhe; Kusters, Cynthia; Vergara, Ximena

2017-06-26

In this paper we compare the findings of epidemiologic studies of childhood leukemia that examined at least two of ELF magnetic fields and/or distance to power lines, and exposure to radon and gamma radiation or distance to nuclear plants. Many of the methodologic aspects are common to studies of non-ionising (i.e. ELF-MF) and ionising radiation. A systematic search and review of studies with more than one exposure under study identified 33 key and 35 supplementary papers from ten countries that have been included in this review. Examining studies that have looked at several radiation exposures, and comparing similarities and differences for the different types of radiation, through the use of directed acyclic graphs, we evaluate to what extent bias, confounding and other methodological issues might be operating in these studies. We found some indication of bias, although results are not clear cut. There is little evidence that confounding has had a substantial influence on results. Influence of the residential mobility on the study conduct and interpretation is complex and can manifest as a selection bias, confounding, increased measurement error or could also be a potential risk factor. Other factors associated with distance to power lines and to nuclear power plants should be investigated. A more complete and consistent reporting of results in the future studies will allow for a more informative comparison across studies and integration of results.

Synthesis, spectral and magnetic studies of mono- and bi-nuclear metal complexes of a new bis(tridentate NO2) Schiff base ligand derived from 4,6-diacetylresorcinol and ethanolamine.

PubMed

Shebl, Magdy

2009-07-15

A new bis(tridentate NO2) Schiff base ligand, H(4)L, was prepared by the reaction of the bifunctional carbonyl compound; 4,6-diacetylresorcinol (DAR) with ethanolamine. The ligand reacted with iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), cerium(III) and uranyl(VI) ions, in absence and in presence of LiOH, to yield mono- and bi-nuclear complexes with different coordinating sites. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. In absence of LiOH, mononuclear complexes (2, 3 and 5-9) as well as binuclear complexes (1 and 4) were obtained. In mononuclear complexes, the ligand acted as a neutral, mono- and di-basic/bi- and tetra-dentate ligand while in binuclear complexes (1 and 4), the ligand acted as a bis(mono- or di-basic/tridentate) ligand. On the other hand, in presence of LiOH, only binuclear complexes (10-15) were obtained in which the ligand acted as a bis(dibasic tridentate) ligand. The metal complexes exhibited different geometrical arrangements such as octahedral, tetrahedral, square planar, square pyramidal and pentagonal bipyramidal arrangements.

High-resolution nuclear magnetic resonance spectroscopic study of metabolites in the cerebrospinal fluid of patients with cervical myelopathy and lumbar radiculopathy

PubMed Central

Morio, Yasuo; Meshitsuka, Shunsuke; Yamane, Koji; Nanjo, Yoshiro; Teshima, Ryota

2010-01-01

There have been few reports describing substances related to oxidative and intermediary metabolism in the cerebrospinal fluid (CSF) in patients with spinal degenerative disorders. This study investigated whether the concentrations of metabolites in the CSF differed between patients with spinal degenerative disorders and controls, and whether the concentrations of these metabolites correlated with the severity of symptoms. CSF samples were obtained from 30 patients with cervical myelopathy (Group M), 30 patients with lumbar radiculopathy (Group R), and 10 volunteers (control). Metabolites in these CSF samples were measured by nuclear magnetic resonance spectroscopy. There were no differences in the concentrations of lactate, alanine, acetate, glutamate, pyruvate, or citrate between Groups M and R, between Group M and the control, or between Group R and the control. In Group M, neither symptom duration nor the Japanese Orthopaedic Association score correlated with the concentration of any metabolite. In Group R, the symptom duration positively correlated with the concentration of lactate, glutamate, and citrate in CSF. The duration of nerve root block showed a negative correlation with the concentrations of acetate in CSF of the patients in Group R. In patients with lumbar radiculopathy, there is a possibility of increased aerobic metabolic activity or decreased gluconeogenic activity in patients with shorter symptom duration, and increased aerobic metabolic activity in patients with severe inflammation around a nerve root. PMID:20490871

JRTF: A Flexible Software Framework for Real-Time Control in Magnetic Confinement Nuclear Fusion Experiments

NASA Astrophysics Data System (ADS)

Zhang, M.; Zheng, G. Z.; Zheng, W.; Chen, Z.; Yuan, T.; Yang, C.

2016-04-01

The magnetic confinement nuclear fusion experiments require various real-time control applications like plasma control. ITER has designed the Fast Plant System Controller (FPSC) for this job. ITER provided hardware and software standards and guidelines for building a FPSC. In order to develop various real-time FPSC applications efficiently, a flexible real-time software framework called J-TEXT real-time framework (JRTF) is developed by J-TEXT tokamak team. JRTF allowed developers to implement different functions as independent and reusable modules called Application Blocks (AB). The AB developers only need to focus on implementing the control tasks or the algorithms. The timing, scheduling, data sharing and eventing are handled by the JRTF pipelines. JRTF provides great flexibility on developing ABs. Unit test against ABs can be developed easily and ABs can even be used in non-JRTF applications. JRTF also provides interfaces allowing JRTF applications to be configured and monitored at runtime. JRTF is compatible with ITER standard FPSC hardware and ITER (Control, Data Access and Communication) CODAC Core software. It can be configured and monitored using (Experimental Physics and Industrial Control System) EPICS. Moreover the JRTF can be ported to different platforms and be integrated with supervisory control software other than EPICS. The paper presents the design and implementation of JRTF as well as brief test results.

Magnetization transfer contrast-suppressed imaging of amide proton transfer and relayed nuclear overhauser enhancement chemical exchange saturation transfer effects in the human brain at 7T.

PubMed

Xu, Xiang; Yadav, Nirbhay N; Zeng, Haifeng; Jones, Craig K; Zhou, Jinyuan; van Zijl, Peter C M; Xu, Jiadi

2016-01-01

To use the variable delay multipulse (VDMP) chemical exchange saturation transfer (CEST) approach to obtain clean amide proton transfer (APT) and relayed Nuclear Overhauser enhancement (rNOE) CEST images in the human brain by suppressing the conventional magnetization transfer contrast (MTC) and reducing the direct water saturation contribution. The VDMP CEST scheme consists of a train of RF pulses with a specific mixing time. The CEST signal with respect to the mixing time shows distinguishable characteristics for protons with different exchange rates. Exchange rate filtered CEST images are generated by subtracting images acquired at two mixing times at which the MTC signals are equal, while the APT and rNOE-CEST signals differ. Because the subtraction is performed at the same frequency offset for each voxel and the CEST signals are broad, no B0 correction is needed. MTC-suppressed APT and rNOE-CEST images of human brain were obtained using the VDMP method. The APT-CEST data show hyperintensity in gray matter versus white matter, whereas the rNOE-CEST images show negligible contrast between gray and white matter. The VDMP approach provides a simple and rapid way of recording MTC-suppressed APT-CEST and rNOE-CEST images without the need for B0 field correction. © 2015 Wiley Periodicals, Inc.