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Sample records for 17o nuclear magnetic

  1. The hyperfine structure in the rotational spectra of D{sub 2}{sup 17}O and HD{sup 17}O: Confirmation of the absolute nuclear magnetic shielding scale for oxygen

    SciTech Connect

    Puzzarini, Cristina Cazzoli, Gabriele; Harding, Michael E.; Vázquez, Juana; Gauss, Jürgen

    2015-03-28

    Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono- and bideuterated-water containing {sup 17}O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spin-rotation (SR) and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular, the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimentally determined {sup 17}O spin-rotation constants of D{sub 2}{sup 17}O and HD{sup 17}O were used to derive the paramagnetic part of the corresponding nuclear magnetic shielding constants. Together with the computed diamagnetic contributions as well as the vibrational and temperature corrections, the latter constants have been employed to confirm the oxygen nuclear magnetic shielding scale, recently established on the basis of spin-rotation data for H{sub 2}{sup 17}O [Puzzarini et al., J. Chem. Phys. 131, 234304 (2009)].

  2. Natural abundance 17O nuclear magnetic resonance and computational modeling studies of lithium based liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Deng, Xuchu; Hu, Mary Y.; Wei, Xiaoliang; Wang, Wei; Chen, Zhong; Liu, Jun; Hu, Jian Zhi

    2015-07-01

    Natural abundance 17O NMR measurements were conducted on electrolyte solutions consisting of Li[CF3SO2NSO2CF3] (LiTFSI) dissolved in the solvents of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and their mixtures at various concentrations. It was observed that 17O chemical shifts of solvent molecules change with the concentration of LiTFSI. The chemical shift displacements of carbonyl oxygen are evidently greater than those of ethereal oxygen, strongly indicating that Li+ ion is coordinated with carbonyl oxygen rather than ethereal oxygen. To understand the detailed molecular interaction, computational modeling of 17O chemical shifts was carried out on proposed solvation structures. By comparing the predicted chemical shifts with the experimental values, it is found that a Li+ ion is coordinated with four double bond oxygen atoms from EC, PC, EMC and TFSI- anion. In the case of excessive amount of solvents of EC, PC and EMC the Li+ coordinated solvent molecules are undergoing quick exchange with bulk solvent molecules, resulting in average 17O chemical shifts. Several kinds of solvation structures are identified, where the proportion of each structure in the liquid electrolytes investigated depends on the concentration of LiTFSI.

  3. Natural Abundance 17O Nuclear Magnetic Resonance and Computational Modeling Studies of Lithium Based Liquid Electrolytes

    SciTech Connect

    Deng, Xuchu; Hu, Mary Y.; Wei, Xiaoliang; Wang, Wei; Chen, Zhong; Liu, Jun; Hu, Jian Z.

    2015-07-01

    Natural abundance 17O NMR measurements were conducted on electrolyte solutions consisting of Li[CF3SO2NSO2CF3] (LiTFSI) dissolved in the solvents of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and their mixtures at various concentrations. It was observed that 17O chemical shifts of solvent molecules change with the concentration of LiTFSI. The chemical shift displacements of carbonyl oxygen are evidently greater than those of ethereal oxygen, strongly indicating that Li+ ion is coordinated with carbonyl oxygen rather than ethereal oxygen. To understand the detailed molecular interaction, computational modeling of 17O chemical shifts was carried out on proposed solvation structures. By comparing the predicted chemical shifts with the experimental values, it is found that a Li+ ion is coordinated with four double bond oxygen atoms from EC, PC, EMC and TFSI- anion. In the case of excessive amount of solvents of EC, PC and EMC the Li+ coordinated solvent molecules are undergoing quick exchange with bulk solvent molecules, resulting in average 17O chemical shifts. Several kinds of solvation structures are identified, where the proportion of each structure in the liquid electrolytes investigated depends on the concentration of LiTFSI.

  4. sup 17 O nuclear-magnetic-resonance spectroscopic study of high- T sub c superconductors

    SciTech Connect

    Oldfield, E.; Coretsopoulos, C.; Yang, S.; Reven, L.; Lee, H.C.; Shore, J.; Han, O.H.; Ramli, E. Materials Research Laboratory, University of Illinois at Urbana; Hinks, D.

    1989-10-01

    We have obtained solid-state {sup 17}O NMR spectra of a number of {sup 17}O-enriched oxides and high-temperature oxide superconductors, including Cu{sub 2}{sup I}O, Cu{sup II}O, KCu{sup III}O{sub 2}, Bi{sub 2}O{sub 3}, Tl{sub 2}O{sub 3}, La{sub 1.85}Sr{sub 0.15}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{ital x}}, Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8+{ital x}}, and Ba{sub 0.6}K{sub 0.4}BiO{sub 3}. Spectra of all of the simple diamagnetic oxides contain relatively sharp resonances in a diamagnetic'' region of {similar to}{minus}200 to +700 ppm (from H{sub 2}O, International Union of Pure and Applied Chemistry {delta} scale). Cu{sup II}O exhibits a broad resonance centered at {similar to}4500 ppm.

  5. Evidence for intrinsic impurities in the high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} from {sup 17}O nuclear magnetic resonance.

    SciTech Connect

    Chen, B.; Mukhopadhyay, S.; Halperin, W. P.; Guptasarma, P.; Hinks, D. G.; Materials Science Division; Northwestern Univ.; Univ. of Wisconsin at Milwaukee

    2008-02-01

    We have found that high quality crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi-2212) have intrinsic magnetic defects that depend on oxygen doping. Our {sup 17}O nuclear magnetic resonance spectra provide evidence that local moments form in the CuO{sub 2} plane in both normal and superconducting states. We suggest that these magnetic impurities are related to the electronic disorder that scanning tunneling microscopy experiments identify with the oxygen dopant atoms.

  6. Dynamic Nuclear Polarization of 17O: Direct Polarization

    PubMed Central

    Michaelis, Vladimir K.; Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2014-01-01

    Dynamic nuclear polarization of 17O was studied using four different polarizing agents – the biradical TOTAPOL, and the monoradicals trityl and SA-BDPA, as well as a mixture of the latter two. Field profiles, DNP mechanisms and enhancements were measured to better understand and optimize directly polarizing this low-gamma quadrupolar nucleus using both mono- and bi-radical polarizing agents. Enhancements were recorded < 88 K and were > 100 using the trityl (OX063) radical and < 10 with the other polarizing agents. The > 10,000 fold savings in acquisition time enabled a series of biologically relevant small molecules to be studied with small sample sizes and the measurement of various quadrupolar parameters. The results are discussed with comparison to room temperature studies and GIPAW quantum chemical calculations. These experimental results illustrate the strength of high field DNP and the importance of radical selection for studying low-gamma nuclei. PMID:24195759

  7. Distal and proximal ligand interactions in heme proteins: Correlations between C-O and Fe-C vibrational frequencies, oxygen-17 and carbon-13 nuclear magnetic resonance chemical shifts, and oxygen-17 nuclear quadrupole coupling constants in C sup 17 O- and sup 13 CO-labeled species

    SciTech Connect

    Ki Deok Park; Guo, K.; Adebodun, F.; Chiu, M.L.; Sligar, S.G.; Oldfield, E. )

    1991-03-05

    The authors have obtained the oxygen-17 nuclear magnetic resonance (NMR) spectra of a variety of C{sup 17}O-labeled heme proteins, including sperm whale (Physeter catodon) myoglobin, two synthetic sperm whale myoglobin mutants (His E7 {yields} Val E7; His E7 {yields} Phe E7), adult human hemoglobin, rabbit (Oryctolagus cuniculus) hemoglobin, horseradish (Cochlearia armoracia) peroxidase isoenzymes A and C, and Caldariomyces fumago chloroperoxidase, in some cases as a function of pH, and have determined their isotropic {sup 17}O NMR chemical shifts, {delta}{sub i}, and spin-lattice relaxation times, T{sub 1}. They have also obtained similar results on a picket fence prophyrin. The results show an excellent correlation between the infrared C-O vibrational frequencies, {nu}(C-O), and {delta}{sub i}, between {nu}(C-O) and the {sup 17}O nuclear quadrupole coupling constant, and as expected between e{sup 2}qQ/h and {delta}{sub i}. The results suggest the IR and NMR measurements reflect the same interaction, which is thought to be primarily the degree of {pi}-back-bonding from Fe d to CO {pi}* orbitals, as outlined previously.

  8. Natural abundant (17) O NMR in a 1.5-T Halbach magnet.

    PubMed

    Sørensen, Morten K; Bakharev, Oleg N; Jensen, Ole; Nielsen, Niels Chr

    2016-06-01

    We present mobile, low-field (17) O NMR as a means for monitoring oxygen in liquids. Whereas oxygen is one of the most important elements, oxygen NMR is limited by a poor sensitivity related to low natural abundance and gyro-magnetic ratio of the NMR active (17) O isotope. Here, we demonstrate (17) O NMR detection at a Larmor frequency of 8.74 MHz in a 1.5-T Halbach neodymium magnet with a home-built digital NMR instrument suitable for large-scale production and in-line monitoring applications. The proposed (17) O NMR sensor may be applied for direct, noninvasive measurements of water content in, for example, oil, manure, or food in automated quality or process control. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25641664

  9. Anomalous enrichment of {sup 17}O and {sup 13}C in photodissociation products of CO{sub 2}: Possible role of nuclear spin

    SciTech Connect

    Mahata, Sasadhar; Bhattacharya, S. K.

    2009-06-21

    Oxygen and carbon isotope fractionation associated with products (CO and O{sub 2}) of gas phase photodissociation of CO{sub 2} have been studied using photons from Hg lamp (184.9 nm) and Kr lamp (123.6 and 116.5 nm). In dissociation by Hg lamp photons both CO and O{sub 2} are enriched in {sup 17}O by about 81 per mille compared to the estimate based on a kinetic model. Additionally, CO is enriched in {sup 13}C by about 37 per mille relative to the model composition. In contrast, in dissociation by higher energy Kr lamp photons no such anomaly was found in O{sub 2}. The observed isotopic enrichments in case of Hg lamp dissociation are proposed to be due to a hyperfine interaction between nuclear spin and electron spins or orbital motion causing enhanced dissociation of isotopologues of CO{sub 2} containing {sup 17}O and {sup 13}C. The {sup 17}O enrichment is higher than that of {sup 13}C by a factor of 2.2{+-}0.2 which can be explained by the known magnetic moment ratio of {sup 17}O and {sup 13}C due to differing nuclear spins and g-factors. These results have potential implications in studies of the planetary atmospheres.

  10. Optically detected magnetic resonance studies of photoexcited /sup 17/O-benzophenone. Orbital rotation in the lowest triplet state

    SciTech Connect

    Waeckerle, G.; Baer, M.; Zimmermann, H.; Dinse, K.H.; Yamauchi, S.; Kashmar, R.J.; Pratt, D.W.

    1982-03-01

    The magnetically active isotope of oxygen /sup 17/O has been used to probe the changes in the electron charge and spin density distributions in oxygen valence orbitals which occur when benzophenone is excited to its lowest triplet state. The data obtained include the optically detected magnetic resonance (ODMR) and electron-nuclear double resonance spectra at both zero and high magnetic fields. New methods of analysis of zero-field ODMR spectra, appropriate when the second-order hyperfine splitting exceeds the quadrupole coupling, are described. This analysis yields the principal values of the electron fine-structure (D), oxygen hyperfine (A), and oxygen quadrupole (Q) tensors, and the orientation of their principal axes with respect to the molecular frame. It is found, consistent with expectations for an n..pi..( state, that the direction of the largest component of Q is different from that of the ground state. It is also found, by two independent methods, that the principal transverse axes of A and Q do not conform to the local C/sub 2v/ symmetry axes of the carbonyl group. This result is interpreted to mean that the axis of the n-type oxygen 2p orbital is rotated out of the carbonyl plane, a rotation which appears to be direct consequence of n..pi..(/..pi pi..( configurational mixing. In agreement with this, the principal values of D, A, and Q are different from those expected for a ''pure'' n..pi..( state. Other consequences of n..pi..(/..pi pi..( mixing, not only in benzophenone but also in the lowest triplet states of other aromatic carbonyls, are discussed briefly.

  11. Magnetic isotope effects in the photolysis of dibenzyl ketone on porous silica. /sup 13/C and /sup 17/O enrichments

    SciTech Connect

    Turro, N.J.; Cheng, C.C.; Wan, P.; Chung, C.; Mahler, W.

    1985-04-25

    The photolysis of dibenzyl ketone (DBK) on porous silica has been investigated. Both /sup 13/C and /sup 17/O isotopic enrichment in the ketone remaining after partial photolysis is demonstrated. The efficiency of /sup 13/C enrichment was found to be relatively insensitive to the average pore diameter of the silica host, to the percent coverage by DBK, and to the application of an external magnetic field. A significant dependence of /sup 13/C enrichment with temperature, with a maximum in the enrichment-temperature profile, was observed. The results are interpreted in terms of the competition between pathways available to the triplet C/sub 6/H/sub 5/CH/sub 2/COCH/sub 2/C/sub 6/H/sub 5/ radical pair produced by photolysis of DBK.

  12. Vortex Lattice Formation in High Magnetic Fields in an Underdoped Single Crystal of Hg1201 from 17O NMR

    NASA Astrophysics Data System (ADS)

    Lee, Jeongseop; Xin, Yizhou; Halperin, W. P.; Reyes, A. P.; Kuhns, P. L.

    The vortex lattice in HgBa2CuO4+δ forms at a vortex melting temperature, Tv, typically ~40K for underdoped crystals with a hole doping ~ 0.11. We present our results from 17O NMR for investigation of the vortex lattice as a function of external magnetic field up to 30 T and temperature as low as 5 K. The vortex contribution to the NMR linewidth can be separated from inhomogeneous broadening by deconvolution of the normal state spectra which was measured separately above, Tv. The vortex melting temperature was measured for two underdoped samples marked by the onset of extra linewidth broadening due to the inhomogeneous magnetic field distribution from the solid vortex lattice consistent with transverse relaxation measurements. We have found evidence for a change in the vortex lattice symmetry as a function of external fields. This work was supported by the DOE BES under Grant No. DE-FG02-05ER46248 and the NHMFL through the NSF and State of Florida.

  13. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Andrew, E. R.

    2009-06-01

    Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

  14. (17)O NMR Investigation of Water Structure and Dynamics.

    PubMed

    Keeler, Eric G; Michaelis, Vladimir K; Griffin, Robert G

    2016-08-18

    The structure and dynamics of the bound water in barium chlorate monohydrate were studied with (17)O nuclear magnetic resonance (NMR) spectroscopy in samples that are stationary and spinning at the magic-angle in magnetic fields ranging from 14.1 to 21.1 T. (17)O NMR parameters of the water were determined, and the effects of torsional oscillations of the water molecule on the (17)O quadrupolar coupling constant (CQ) were delineated with variable temperature MAS NMR. With decreasing temperature and reduction of the librational motion, we observe an increase in the experimentally measured CQ explaining the discrepancy between experiments and predictions from density functional theory. In addition, at low temperatures and in the absence of (1)H decoupling, we observe a well-resolved (1)H-(17)O dipole splitting in the spectra, which provides information on the structure of the H2O molecule. The splitting arises because of the homogeneous nature of the coupling between the two (1)H-(17)O dipoles and the (1)H-(1)H dipole. PMID:27454747

  15. /sup 17/O NMR spectroscopy of magnetically ordered YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ microcrystals

    SciTech Connect

    Coretsopoulos, C.; Lee, H.C.; Ramli, E.; Reven, L.; Rauchfuss, T.B.; Oldfield, E.

    1989-01-01

    We have obtained /sup 17/O NMR spectra of powder samples of YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/ and EuBa/sub 2/Cu/sub 3/O/sub 7-//sub x/, as well as magnetically ordered YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/. Two major features are observed in YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/: a sharp resonance at approx. =1800 ppm (from external H/sub 2//sup 17/O, International Union of Pure and Applied Chemistry delta scale) and a broader series of features centered at approx. =400 ppm. The 1800-ppm feature undergoes a diamagnetic shift of approx. =800 ppm on cooling to 77 K, and a similar magnitude shift on Eu substitution, suggesting assignment to the plane oxygens, O(2,3). Measurements on magnetically ordered samples at 8.45 and 11.7 T give the magnitude of the diagonal terms of the electric field gradient tensor, which are 2.3, 3.5, and 5.8 MHz. For the columnar oxygen, O(1), we find e/sup 2/qQ/h = 7.7 MHz, with a chemical shift anisotropy of approx. =660 ppm.

  16. 17O nuclear quadrupole coupling constants of water bound to a metal ion: A gadolinium(III) case study

    NASA Astrophysics Data System (ADS)

    Yazyev, Oleg V.; Helm, Lothar

    2006-08-01

    Rotational correlation times of metal ion aqua complexes can be determined from O17 NMR relaxation rates if the quadrupole coupling constant of the bound water oxygen-17 nucleus is known. The rotational correlation time is an important parameter for the efficiency of Gd3+ complexes as magnetic resonance imaging contrast agents. Using a combination of density functional theory with classical and Car-Parrinello molecular dynamics simulations we performed a computational study of the O17 quadrupole coupling constants in model aqua ions and the [Gd(DOTA)(H2O)]- complex used in clinical diagnostics. For the inner sphere water molecule in the [Gd(DOTA)(H2O)]- complex the determined quadrupole coupling parameter χ√1+η2/3 of 8.7MHz is very similar to that of the liquid water (9.0MHz ). Very close values were also predicted for the the homoleptic aqua ions of Gd3+ and Ca2+. We conclude that the O17 quadrupole coupling parameters of water molecules coordinated to closed shell and lanthanide metal ions are similar to water molecules in the liquid state.

  17. sup 17 O, sup 1 H, and sup 2 H electron nuclear double resonance characterization of solvent, substrate, and inhibitor binding to the (4Fe-4S) sup + cluster of aconitase

    SciTech Connect

    Werst, M.M.; Hoffman, B.M. ); Kennedy, M.C.; Beinert, H. )

    1990-11-01

    {sup 17}O electron nuclear double resonance (ENDOR) studies at X-band (9-GHz) and Q-band (35-GHz) microwave frequencies reveal that the (4Fe-4S){sup {plus}} cluster of substrate-free aconitase (citrate (isocitrate) hydro-lyase, EC 4.2.1.3) binds solvent, H{sub x}O (x = 1,2). Previous {sup 17}O ENDOR studies had disclosed that H{sub x}{sup 17}O binds to the enzyme-substrate complex and also to complexes of enzyme with the substrate analogues trans-aconitate and nitroisocitrate (1-hydroxy-2-nitro-1,3-propanedicarboxylate). The authors have used {sup 1}H and {sup 2}H ENDOR to characterize these solvent species. The authors propose that the fourth ligand of Fe{sub a} in substrate-free enzyme is a hydroxyl ion from the solvent; upon binding of substrate or substrate analogues at this Fe{sub a} site, the solvent species becomes protonated to form a water molecule. Previous {sup 17}O and {sup 13}C ENDOR studies showed that only a single carboxyl, at C-2 of the propane backbone of cis-aconitate or at C-1 of the inhibitor nitroisocitrate, coordinates to the cluster. Together, these results imply that enzyme-catalyzed interconversion of citrate and isocitrate does not involve displacement of an endogenous fourth ligand, but rather addition of the anionic carboxylate ligand and a change in protonation state of a solvent species bound to Fe{sub a}. The authors further report the {sup 17}O hyperfine tensor parameters of the C-2 carboxyl oxygen of substrate bound to the cluster as determined by the field dependence of the {sup 17}O ENDOR signals. {sup 17}O ENDOR studies also show that the carboxyl group of the inhibitor trans-aconitate binds similarly to that off substrate.

  18. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Larsen, Michael; Griffith, Robert; Bulatowicz, Michael

    2014-03-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation (NGC) has concluded the fourth and final phase of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. Traditional MEMS gyros utilize springs as an inherent part of the sensing mechanism, leading to bias and scale factor sensitivity to acceleration and vibration. As a result, they have not met performance expectations in real world environments and to date have been limited to tactical grade applications. The Nuclear Magnetic Resonance Gyroscope (NMRG) utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as an inertial reference for determining rotation. The nuclear spin precession rate sensitivity to acceleration and vibration is negligible for most applications. Therefore, the application of new micro and batch fabrication methods to NMRG technology holds great promise for navigation grade performance in a low cost and compact gyro. This presentation will describe the operational principles, design basics, and demonstrated performance of the NMRG including an overview of the NGC designs developed and demonstrated in the DARPA gyro development program.

  19. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Clark, Philip; Griffith, Robert; Larsen, Michael; Mirijanian, James

    2012-06-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation is concluding the fourth and final phase of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. Traditional MEMS gyros utilize springs as an inherent part of the sensing mechanism, leading to bias and scale factor sensitivity to acceleration and vibration. As a result, they have not met performance expectations in real world environments and to date have been limited to tactical grade applications. The Nuclear Magnetic Resonance Gyroscope (NMRG) utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as an inertial reference for determining rotation. The nuclear spin precession rate sensitivity to acceleration and vibration is negligible for most applications. Therefore, the application of new micro and batch fabrication methods to NMRG technology holds great promise for navigation grade performance in a low cost and compact gyro. This poster will describe the history, operational principles, and design basics of the NMRG including an overview of the NSD designs developed and demonstrated in the DARPA gyro development program. General performance results from phases 3 and 4 will also be presented.

  20. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Griffith, Robert; Larsen, Michael

    2014-03-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation (NGC) has concluded the fourth and final phase of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. Traditional MEMS gyros utilize springs as an inherent part of the sensing mechanism, leading to bias and scale factor sensitivity to acceleration and vibration. As a result, they have not met performance expectations in real world environments and to date have been limited to tactical grade applications. The Nuclear Magnetic Resonance Gyroscope (NMRG) utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as an inertial reference for determining rotation. The nuclear spin precession rate sensitivity to acceleration and vibration is negligible for most applications. Therefore, the application of new micro and batch fabrication methods to NMRG technology holds great promise for navigation grade performance in a low cost and compact gyro. This poster will describe the history, operational principles, design, and demonstrated performance of the NMRG including an overview of the NGC designs developed and demonstrated in the DARPA gyro development program.

  1. Nuclear Magnetic Conduits

    NASA Astrophysics Data System (ADS)

    Desantis, Rich

    2008-10-01

    Point charges are not conduits of magnetism. Vacuum gaps between charges prevent superconductivity. Magnetism occurs w/o charge velocity. A changing magnetic field can add magnetism, w/o magnetism's centripetal force adding speed. Voltage is not charge repulsion energy. Passing electrons through a stationary electron's field cannot reduce its field. Passing the external electrons through a charged capacitor's field discharges the capacitor. Chemical bonds extend between atoms. A superconductive magnet contains a superconductive molecule, the length of its wire. Superconductivity dictates that chemical bonding material is non-vacuum and non-point charge. Its unit is an electron/proton fusion called an ABION. Unpaired abions attract all other unpaired abions within or between atoms. Paired abions have reduced attraction for other abions. Helium is inert because its abions are paired. A lithium atom includes an unpaired abion. Superconductive abions are nuclear magnetic conduits. Equality of transference numbers in electrochemistry is evidence of conduits. In fuel cells and semiconductors, paired voltage-induced redox reactions convert lines of abions into conduits. This temporarily converts bulk insulators to conductors.

  2. Understanding the symmetric line shape in the 17O MAS spectra for hexagonal ice

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Oki, Shinobu; Deguchi, Kenzo; Shimizu, Tadashi

    2016-06-01

    Solid-state 17O Magic-Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectra of 17O-enriched hexagonal ice, [17O]-Ih, between 173 and 253 K were presented. Marked changes in the line shape were clearly observed, indicating water molecular reorientation in the crystal structure. At 173 K, molecular motions were considered to be frozen and analysis of the 1D MAS spectrum yielded the following parameters: quadrupole coupling constant (CQ) = 6.6 ± 0.2 MHz and asymmetry parameter (ηQ) = 0.95 ± 0.05. At 232 K and above, contrary to the conventional explanation, pseudo-symmetric line shapes appeared in the 17O MAS NMR spectra arising from the contribution of second-order quadrupole interactions. As a chemical exchange model to describe these isotropic 17O MAS NMR spectra, a modified Ratcliffe model, which consider the effects of proton disorder, was proposed, and the resulting theoretical spectra could well reproduce the experimental spectra.

  3. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Larsen, Michael

    2011-05-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation is currently in phase 4 of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. The micro-NMRG technology is pushing the boundaries of size, weight, power, and performance allowing new small platform applications of navigation grade Inertial Navigation System (INS) technology. Information on the historical development of the technology, basics of operation, task performance goals, application opportunities, and a phase 2 sample of earth rate measurement data will be presented. Funding Provided by the Defense Advanced Research Projects Agency (DARPA)

  4. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Larsen, Michael; Bulatowicz, Michael; Clark, Philip; Griffith, Robert; Mirijanian, James; Pavell, James

    2015-05-01

    The Nuclear Magnetic Resonance Gyroscope (NMRG) is being developed by the Northrop Grumman Corporation (NGC). Cold and hot atom interferometer based gyroscopes have suffered from Size, Weight, and Power (SWaP) challenges and limits in bandwidth, scale factor stability, dead time, high rotation rate, vibration, and acceleration. NMRG utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as a reference for determining rotation, providing continuous measurement, high bandwidth, stable scale factor, high rotation rate measurement, and low sensitivity to vibration and acceleration in a low SWaP package. The sensitivity to vibration has been partially tested and demonstrates no measured sensitivity within error bars. Real time closed loop implementation of the sensor significantly decreases environmental and systematic sensitivities and supports a compact and low power digital signal processing and control system. Therefore, the NMRG technology holds great promise for navigation grade performance in a low cost SWaP package. The poster will describe the history, operation, and design of the NMRG. General performance results will also be presented along with recent vibration test results.

  5. Probing surface hydrogen bonding and dynamics by natural abundance, multidimensional, 17O DNP-NMR spectroscopy

    DOE PAGESBeta

    Perras, Frederic A.; Chaudhary, Umesh; Slowing, Igor I.; Pruski, Marek

    2016-05-06

    Dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy is increasingly being used as a tool for the atomic-level characterization of surface sites. DNP surface-enhanced SSNMR spectroscopy of materials has, however, been limited to studying relatively receptive nuclei, and the particularly rare 17O nuclide, which is of great interest for materials science, has not been utilized. We demonstrate that advanced 17O SSNMR experiments can be performed on surface species at natural isotopic abundance using DNP. We use 17O DNP surface-enhanced 2D SSNMR to measure 17O{1H} HETCOR spectra as well as dipolar oscillations on a series of thermally treatedmore » mesoporous silica nanoparticle samples having different pore diameters. These experiments allow for a nonintrusive and unambiguous characterization of hydrogen bonding and dynamics at the surface of the material; no other single experiment can give such details about the interactions at the surface. Lastly, our data show that, upon drying, strongly hydrogen-bonded surface silanols, whose motions are greatly restricted by the interaction when compared to lone silanols, are selectively dehydroxylated.« less

  6. Theoretical Study of the Electrostatic and Steric Effects on the Spectroscopic Characteristics of the Metal-Ligand Unit of Heme Proteins. 2. C-O Vibrational Frequencies, 17O Isotropic Chemical Shifts, and Nuclear Quadrupole Coupling Constants

    PubMed Central

    Kushkuley, Boris; Stavrov, Solomon S.

    1997-01-01

    The quantum chemical calculations, vibronic theory of activation, and London-Pople approach are used to study the dependence of the C-O vibrational frequency, 17O isotropic chemical shift, and nuclear quadrupole coupling constant on the distortion of the porphyrin ring and geometry of the CO coordination, changes in the iron-carbon and iron-imidazole distances, magnitude of the iron displacement out of the porphyrin plane, and presence of the charged groups in the heme environment. It is shown that only the electrostatic interactions can cause the variation of all these parameters experimentally observed in different heme proteins, and the heme distortions could modulate this variation. The correlations between the theoretically calculated parameters are shown to be close to the experimentally observed ones. The study of the effect of the electric field of the distal histidine shows that the presence of the four C-O vibrational bands in the infrared absorption spectra of the carbon monoxide complexes of different myoglobins and hemoglobins can be caused by the different orientations of the different tautomeric forms of the distal histidine. The dependence of the 17O isotropic chemical shift and nuclear quadrupole coupling constant on pH and the distal histidine substitution can be also explained from the same point of view. PMID:9017215

  7. Identification of different oxygen species in oxide nanostructures with (17)O solid-state NMR spectroscopy.

    PubMed

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P; Peng, Luming

    2015-02-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the (17)O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency (17)O chemical shifts being observed for the lower coordinated surface sites. H2 (17)O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. (17)O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications. PMID:26601133

  8. GHz nuclear magnetic resonance

    SciTech Connect

    Cross, T.A.; Drobny, G.; Trewhella, J.

    1994-12-01

    For the past dozen years, 500- and 600-MHz spectrometers have become available in many laboratories. The first 600-MHz NMR spectrometer (at Carnegie Mellon University) was commissioned more than 15 years ago and, until 1994, represented the highest field available for high-resolution NMR. This year, we have witnessed unprecedented progress in the development of very high field magnets for NMR spectroscopy, including the delivery of the first commercial 750-MHz NMR spectrometers. In addition, NMR signals have been obtained from 20-Tesla magnets (850 MHz for {sup 1}H`s) at both Los Alamos National Laboratory and Florida State University in the NHMFL (National High Magnetic Field Laboratory). These preliminary experiments have been performed in magnets with 100-ppm homogeneity, but a 20-Tesla magnet developed for the NHMFL will be brought to field this year with a projected homogeneity of 0.1 ppm over a 1-cm-diam spherical volume.

  9. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    PubMed

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom. PMID:26670708

  10. Probing oxidative degradation in polymers using {sup 17}O NMR spectroscopy

    SciTech Connect

    Alam, T.M.; Click, C.A.; Assink, R.A.

    1997-09-01

    Understanding the mechanism of oxidative degradation remains an important goal in being able to predict the aging process in polymer materials. Nuclear magnetic resonance (NMR) spectroscopy has previously been utilized to investigate polymer degradation, including both proton ({sup 1}H) and carbon ({sup 13}C) studies. These previous NMR studies, as well as other spectroscopic investigations, are complicated by the almost overwhelming signal arising from the native undegraded polymer. This makes the identification and quantification of degradation species at small concentrations difficult. In this note we discuss recent investigation into the use of oxygen ({sup 17}O) NMR spectroscopy to probe the oxidative degradation process in polymers at a molecular level. Due to the low natural abundance (0.037%) and a nuclear spin of I=5/2 possessing an appreciable quadrupolar moment, the use of {sup 17}O NMR in polymer investigations has been limited. By utilizing synthetically enriched oxygen gas during the accelerated aging process, both the difficulties of low natural abundance and background interference signals are eliminated. For enriched samples {sup 17}O NMR spectra now provide a unique probe since all of the observed NMR resonances are the direct result of oxidative degradation.

  11. Theory of nuclear magnetic relaxation

    NASA Technical Reports Server (NTRS)

    Mcconnell, J.

    1983-01-01

    A theory of nuclear magnetic interaction is based on the study of the stochastic rotation operator. The theory is applied explicitly to relaxation by anisotropic chemical shift and to spin-rotational interactions. It is applicable also to dipole-dipole and quadrupole interactions.

  12. Identification of different oxygen species in oxide nanostructures with 17O solid-state NMR spectroscopy

    PubMed Central

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P.; Peng, Luming

    2015-01-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the 17O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency 17O chemical shifts being observed for the lower coordinated surface sites. H217O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. 17O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications. PMID:26601133

  13. 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.

  14. Nuclear matter magnetization in the Skyrme model

    SciTech Connect

    Aguirre, R.

    2011-05-15

    The effects of an external magnetic field on the nuclear medium are studied within the Skyrme model of the nuclear interaction. The equation of state, spin polarization, and magnetization are evaluated at zero temperature for both neutron matter and isospin symmetric nuclear matter. We consider the anomalous magnetic moments of the nucleons and the quantization induced by a magnetic field over the proton energy spectrum. A comparison of two versions of the model, allowing or not for spontaneous magnetization, is performed. We cover a range of magnetic-field strengths and matter densities appropriate for astrophysical studies.

  15. 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.

  16. Evanescent Waves Nuclear Magnetic Resonance

    PubMed Central

    Halidi, El Mohamed; Nativel, Eric; Akel, Mohamad; Kenouche, Samir; Coillot, Christophe; Alibert, Eric; Jabakhanji, Bilal; Schimpf, Remy; Zanca, Michel; Stein, Paul; Goze-Bac, Christophe

    2016-01-01

    Nuclear Magnetic Resonance spectroscopy and imaging can be classified as inductive techniques working in the near- to far-field regimes. We investigate an alternative capacitive detection with the use of micrometer sized probes positioned at sub wavelength distances of the sample in order to characterize and model evanescent electromagnetic fields originating from NMR phenomenon. We report that in this experimental configuration the available NMR signal is one order of magnitude larger and follows an exponential decay inversely proportional to the size of the emitters. Those investigations open a new road to a better understanding of the evanescent waves component in NMR with the opportunity to perform localized spectroscopy and imaging. PMID:26751800

  17. Nuclear Magnetic Resonance Study of High Temperature Superconductivity

    NASA Astrophysics Data System (ADS)

    Mounce, Andrew M.

    The high temperature superconductors HgBa2CuO 4+delta (Hg1201) and Bi2SrCa2Cu2O 8+delta (Bi2212) have been treated with 17O for both nuclear magnetic resonance (NMR) sensitivity and various electronic properties. Subsequently, NMR experiments were performed on Hg1201 and Bi2212 to reveal the nature of the pseudogap, in the normal state, and vortex phases, in the superconducting state. NMR has been performed on 17O in an underdoped Hg1201 crystal with a superconducting transition transition temperature of 74 K to look for circulating orbital currents proposed theoretically and inferred from neutron scattering. The measurements reveal narrow spectra which preclude static local fields in the pseudogap phase at the apical site, suggesting that the moments observed with neutrons are fluctuating or the orbital current ordering is not the correct model for the neutron scattering observation. The fine detail of the NMR frequency shifts at the apical oxygen site are consistent with a dipolar field from the Cu+2 site and diamagnetism below the superconducting transition. It has been predicted that superconducting vortices should be electrically charged and that this effect is particularly enhanced for high temperature superconductors. Here it is shown that the Abrikosov vortex lattice, characteristic of the mixed state of superconductors, will become unstable at sufficiently high magnetic field if there is charge trapped on the vortex core for highly anisotropic superconductors. NMR measurements of the magnetic fields generated by vortices in Bi2212 single crystals provide evidence for an electro-statically driven vortex lattice reconstruction with the magnitude of charge on each vortex pancake of 2x10-3e, depending on doping, in line with theoretical estimates. Competition with magnetism is at the heart of high temperature superconductivity, most intensely felt near a vortex core. To investigate vortex magnetism spatially resolved NMR has been used, finding a strongly non

  18. Synchronously pumped nuclear magnetic oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Thrasher, Daniel; Bulatowicz, Michael; Walker, Thad

    2015-05-01

    We present progress towards a synchronously pumped nuclear magnetic oscillator. Alkali frequency shifts and quadrupole shifts are the dominant systematic effects in dual Xe isotope co-magnetometers. By synchronously pumping the Xe nuclei using spin-exchange with an oscillating Rb polarization, the Rb and Xe spins precess transverse to the longitudinal bias field. This configuration is predicted to be insensitive to first order quadrupole interactions and alkali spin-exchange frequency shifts. A key feature that allows co-precession of the Rb and Xe spins, despite a ~ 1000 fold ratio of their gyromagnetic ratios, is to apply the bias field in the form of a sequence of Rb 2 π pulses whose repetition frequency is equal to the Rb Larmor frequency. The 2 π pulses result in an effective Rb magnetic moment of zero, while the Xe precession depends only on the time average of the pulsed field amplitude. Polarization modulation of the pumping light at the Xe NMR frequency allows co-precession of the Rb and Xe spins. We will present our preliminary experimental studies of this new approach to NMR of spin-exchange pumped Xe. Support by the NSF and Northrop Grumman Co.

  19. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-05-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  20. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-08-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  1. Tracing Nitrate Deposition Using Δ 17O

    NASA Astrophysics Data System (ADS)

    Michalski, G m; Hernandez, L.; Meixner, T.; Fenn, M.; Thiemens, M.

    2001-12-01

    Assessing the impact of atmospheric deposition of fixed nitrogen on local, regional, and global biogeochemical cycles has received much attention in recent years. Local and regional ecosystems can suffer from eutrophication and shrinking biodiversity from the increased nitrogen flux, in addition to degradation associated with acid rain ( an increasing proportion of which is as HNO3 ). On a global scale, the effect of nitrogen fertilization on CO2 uptake rates is one of the biggest unknowns in global warming research. This renewed interest has led to new attempts to utilize current, and in the development of new, analytical techniques in order to better understand the source, sink and transport mechanisms of atmospheric nitrogen deposition. Its role as the primary sink of the NOx cycle makes atmospheric nitrate (as particulate nitrate or nitric acid ) the primary source of nitrogen deposition. Stable isotopes of nitrogen and oxygen have been used by several researchers to trace atmospheric nitrate through the biogeochemical system. 15N ratios have been problematic due to the lack of large fractionations and an overlap of 15N ratios between sources. Initial studies of 18O ratios showed promise due to the large enrichment (60 ‰ ) in atmospheric nitrate. However, subsequent studies showed an δ 18O spread of 25 - 80 ‰ and have made quantitative analysis of mixing reservoirs difficult. No studies of δ 17O nitrates have been published. For δ 17O, thermodynamic, kinetic, and equilibrium isotope effects dictate that δ 17O = .52 x δ 18O . Certain photochemical processes violate this rule due to quantum effects and are quantified by Δ 17O = δ 17O -.52 x δ 18O which are called mass independent fractionations (MIF). Atmospheric nitrates have now been measured and have been found to have a large MIF; Δ 17O ~ 25 ‰ and a small range +/- 4‰ . The large variations in δ 18O of atmospheric nitrate are due to mass dependent fractions from transport and source ratios

  2. Natural abundance 17O DNP two-dimensional and surface-enhanced NMR spectroscopy

    DOE PAGESBeta

    Perras, Frédéric A.; Kobayashi, Takeshi; Pruski, Marek

    2015-06-22

    Due to its extremely low natural abundance and quadrupolar nature, the 17O nuclide is very rarely used for spectroscopic investigation of solids by NMR without isotope enrichment. Additionally, the applicability of dynamic nuclear polarization (DNP), which leads to sensitivity enhancements of 2 orders of magnitude, to 17O is wrought with challenges due to the lack of spin diffusion and low polarization transfer efficiency from 1H. Here, we demonstrate new DNP-based measurements that extend 17O solid-state NMR beyond its current capabilities. The use of the PRESTO technique instead of conventional 1H–17O cross-polarization greatly improves the sensitivity and enables the facile measurementmore » of undistorted line shapes and two-dimensional 1H–17O HETCOR NMR spectra as well as accurate internuclear distance measurements at natural abundance. This was applied for distinguishing hydrogen-bonded and lone 17O sites on the surface of silica gel; the one-dimensional spectrum of which could not be used to extract such detail. As a result, this greatly enhanced sensitivity has enabled, for the first time, the detection of surface hydroxyl sites on mesoporous silica at natural abundance, thereby extending the concept of DNP surface-enhanced NMR spectroscopy to the 17O nuclide.« less

  3. 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.

  4. Nuclear Magnetic Resonance Technology for Medical Studies

    NASA Astrophysics Data System (ADS)

    Budinger, Thomas F.; Lauterbur, Paul C.

    1984-10-01

    Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region nuclear magnetic resonance spectroscopy of protons, carbon-13, and phosphorus-31 has developed into a basic science tool for in vivo studies on man and a unique tool for clinical diagnoses of metabolic disorders. At present, nuclear magnetic resonance is considered safe if access to the magnet environment is controlled. Technological advances employing field strengths over 2 teslas will require biophysical studies of heating and static field effects.

  5. 17O NMR study of the doped electrons in lightly oxygen-deficient cubic SrMnO3 -x

    NASA Astrophysics Data System (ADS)

    Trokiner, A.; Verkhovskii, S.; Volkova, Z.; Gerashenko, A.; Mikhalev, K.; Germov, A.; Yakubovskii, A.; Korolev, A.; Dabrowski, B.; Tyutyunnik, A.

    2016-05-01

    The spin susceptibility of the localized Mn (t2 g) electrons, χs, and the spatially distributed spin density of the doped electrons were investigated by 17O nuclear magnetic resonance (NMR) in the paramagnetic (PM) and antiferromagnetic (AF) phases of electron-doped SrMnO3 -x ceramics with the cubic structure. Three lightly doped samples (2 x <0.015 ) were studied with TN=220 K-240 K. In the PM state χs increases gradually from TN and reaches a broad maximum above ˜1.5 TN . The gapped behavior of χs indicates a low-dimensional short-range spin order persisting above TN. These short-range one-dimensional correlations are consistent with 17O NMR results obtained at room temperature, which show that Mn magnetic moments are aligned along the edges of the cubic unit cell. Above 350 K all doped electrons are fast-moving eg electrons. They provide the uniform polarization of the localized spins which increases χs and the increasing doping shifts the oxygen-deficient SrMnO3 -x oxide towards a ferromagnetic (FM) metallic state. At lower T the doped electrons are heterogeneously distributed in the oxide: The fraction of the fast-moving electrons diminishes and vanishes below 100 K, while the remaining doped electrons slow down their hopping and each of them creates a FM domain. These FM domains which are detected below 10 K by 55Mn NMR can be considered as small-size magnetic polarons. Their T -activated hopping in the G-type AF lattice was probed by 17O spin-echo experiments. The energy barrier of hopping shows a trend to grow with increasing doping, indicating that the de Gennes metallic ground state cannot be achieved in oxygen-deficient SrMnO3 -x oxides, probably due to detrimental oxygen vacancy defects.

  6. Nuclear magnetic resonance contrast agents

    DOEpatents

    Smith, Paul H.; Brainard, James R.; Jarvinen, Gordon D.; Ryan, Robert R.

    1997-01-01

    A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC.sub.16 H.sub.14 N.sub.6. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques.

  7. Nuclear magnetic resonance contrast agents

    DOEpatents

    Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.

    1997-12-30

    A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 10 figs.

  8. Nuclear magnetic resonance in Kondo lattice systems

    NASA Astrophysics Data System (ADS)

    Curro, Nicholas J.

    2016-06-01

    Nuclear magnetic resonance has emerged as a vital tool to explore the fundamental physics of Kondo lattice systems. Because nuclear spins experience two different hyperfine couplings to the itinerant conduction electrons and to the local f moments, the Knight shift can probe multiple types of spin correlations that are not accessible via other techniques. The Knight shift provides direct information about the onset of heavy electron coherence and the emergence of the heavy electron fluid.

  9. Nuclear Magnetic Resonance Studies on Vanadium(IV) Electrolyte Solutions for Vanadium Redox Flow Battery

    SciTech Connect

    Vijayakumar, M.; Burton, Sarah D.; Huang, Cheng; Li, Liyu; Yang, Zhenguo; Graff, Gordon L.; Liu, Jun; Hu, Jian Z.; Skyllas-Kazacos, Maria

    2010-11-15

    The vanadium (IV) electrolyte solutions with various vanadium concentrations are studied by variable temperature 1H and 17O Nuclear Magnetic Resonance (NMR) spectroscopy. The structure and kinetics of vanadium (IV) species in the electrolyte solutions are explored with respect to vanadium concentration and temperature. It was found that the vanadium (IV) species exist as hydrated vanadyl ion, i.e. [VO(H2O)5]2+ forming an octahedral coordination with vanadyl oxygen in the axial position and the remaining positions occupied by water molecules. This hydrated vanadyl ion structure is stable in vanadium concentrations up to 3M and in the temperature range of 240 to 340 K. The sulfate anions in the electrolyte solutions are found to be weekly bound to this hydrated vanadyl ion and occupies its second coordination sphere. The possible effects of these sulfate anions in proton and water exchange between vanadyl ion and solvent molecules are discussed based on 1H and 17O NMR results.

  10. 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…

  11. Phosphonate Based High Nuclearity Magnetic Cages.

    PubMed

    Sheikh, Javeed Ahmad; Jena, Himanshu Sekhar; Clearfield, Abraham; Konar, Sanjit

    2016-06-21

    Transition metal based high nuclearity molecular magnetic cages are a very important class of compounds owing to their potential applications in fabricating new generation molecular magnets such as single molecular magnets, magnetic refrigerants, etc. Most of the reported polynuclear cages contain carboxylates or alkoxides as ligands. However, the binding ability of phosphonates with transition metal ions is stronger than the carboxylates or alkoxides. The presence of three oxygen donor sites enables phosphonates to bridge up to nine metal centers simultaneously. But very few phosphonate based transition metal cages were reported in the literature until recently, mainly because of synthetic difficulties, propensity to result in layered compounds, and also their poor crystalline properties. Accordingly, various synthetic strategies have been followed by several groups in order to overcome such synthetic difficulties. These strategies mainly include use of small preformed metal precursors, proper choice of coligands along with the phosphonate ligands, and use of sterically hindered bulky phosphonate ligands. Currently, the phosphonate system offers a library of high nuclearity transition metal and mixed metal (3d-4f) cages with aesthetically pleasing structures and interesting magnetic properties. This Account is in the form of a research landscape on our efforts to synthesize and characterize new types of phosphonate based high nuclearity paramagnetic transition metal cages. We quite often experienced synthetic difficulties with such versatile systems in assembling high nuclearity metal cages. Few methods have been emphasized for the self-assembly of phosphonate systems with suitable transition metal ions in achieving high nuclearity. We highlighted our journey from 2005 until today for phosphonate based high nuclearity transition metal cages with V(IV/V), Mn(II/III), Fe(III), Co(II), Ni(II), and Cu(II) metal ions and their magnetic properties. We observed that

  12. Nuclear magnetic resonance in magnets with a helicoidal magnetic structure in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-11-01

    In this review, the static and dynamic properties of a magnet with a helicoidal magnetic structure placed in an external magnetic field are discussed. The results of the investigation of its ground state and spectra, as well as the amplitudes of the spin excitations are presented. The temperature and field dependences of the basic thermodynamic characteristics (heat capacity, magnetization, and magnetic susceptibility) have been calculated in the spin-wave approximation. The results of calculating the local and integral dynamic magnetic susceptibility are given. This set of data represents a methodical basis for constructing a consistent (in the framework of unified approximations) picture of the NMR absorption in the magnet under consideration. Both local NMR characteristics (resonance frequency, line broadening, enhancement coefficient) and integral characteristics (resultant shape of the absorption line with its specific features) have been calculated. The effective Hamiltonian of the Suhl-Nakamura interaction of nuclear spins through spin waves has been constructed. The second moment and the local broadening of the line of the NMR absorption caused by this interaction have been calculated. The role of the basic local inhomogeneities in the formation of the integral line of the NMR absorption has been analyzed. The opportunities for the experimental NMR investigations in magnets with a chiral spin structure are discussed.

  13. Nuclear magnetic resonance studies of lens transparency

    SciTech Connect

    Beaulieu, C.F.

    1989-01-01

    Transparency of normal lens cytoplasm and loss of transparency in cataract were studied by nuclear magnetic resonance (NMR) methods. Phosphorus ({sup 31}P) NMR spectroscopy was used to measure the {sup 31}P constituents and pH of calf lens cortical and nuclear homogenates and intact lenses as a function of time after lens enucleation and in opacification produced by calcium. Transparency was measured with laser spectroscopy. Despite complete loss of adenosine triphosphate (ATP) within 18 hrs of enucleation, the homogenates and lenses remained 100% transparent. Additions of calcium to ATP-depleted cortical homogenates produced opacification as well as concentration-dependent changes in inorganic phosphate, sugar phosphates, glycerol phosphorylcholine and pH. {sup 1}H relaxation measurements of lens water at 200 MHz proton Larmor frequency studied temperature-dependent phase separation of lens nuclear homogenates. Preliminary measurements of T{sub 1} and T{sub 2} with non-equilibrium temperature changes showed a change in the slope of the temperature dependence of T{sub 1} and T{sub 2} at the phase separation temperature. Subsequent studies with equilibrium temperature changes showed no effect of phase separation on T{sub 1} or T{sub 2}, consistent with the phase separation being a low-energy process. {sup 1}H nuclear magnetic relaxation dispersion (NMRD) studies (measurements of the magnetic field dependence of the water proton 1/T{sub 1} relaxation rates) were performed on (1) calf lens nuclear and cortical homogenates (2) chicken lens homogenates, (3) native and heat-denatured egg white and (4) pure proteins including bovine {gamma}-II crystallin bovine serum albumin (BSA) and myoglobin. The NMRD profiles of all samples exhibited decreases in 1/T{sub 1} with increasing magnetic field.

  14. 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.

  15. 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.

  16. An introduction to biomedical nuclear magnetic resonance

    SciTech Connect

    Petersen, S.B.; Muller, R.N.; Rinck, P.A.

    1985-01-01

    Separated into three sections, this book gives an overview on the principles of nuclear magnetic spectroscopy and the imaging procedures based upon this technique, an insight into the parameters which have influence on the NMR image, e.g. relaxation times, flow and contrast, and finally an account of medical applications in the brain, the spine, the cardiovascular system, the abdomen, and in tumor imaging.

  17. The Diversity of Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Corey W.; Alekseyev, Viktor Y.; Allwardt, Jeffrey R.; Bankovich, Alexander J.; Cade-Menun, Barbara J.; Davis, Ronald W.; Du, Lin-Shu; Garcia, K. Christopher; Herschlag, Daniel; Khosla, Chaitan; Kraut, Daniel A.; Li, Qing; Null, Brian; Puglisi, Joseph D.; Sigala, Paul A.; Stebbins, Jonathan F.; Varani, Luca

    The discovery of the physical phenomenon of Nuclear Magnetic Resonance (NMR) in 1946 gave rise to the spectroscopic technique that has become a remarkably versatile research tool. One could oversimplify NMR spectros-copy by categorizing it into the two broad applications of structure elucidation of molecules (associated with chemistry and biology) and imaging (associated with medicine). But, this certainly does not do NMR spectroscopy justice in demonstrating its general acceptance and utilization across the sciences. This manuscript is not an effort to present an exhaustive, or even partial review of NMR spectroscopy applications, but rather to provide a glimpse at the wide-ranging uses of NMR spectroscopy found within the confines of a single magnetic resonance research facility, the Stanford Magnetic Resonance Laboratory. Included here are summaries of projects involving protein structure determination, mapping of intermolecular interactions, exploring fundamental biological mechanisms, following compound cycling in the environmental, analysis of synthetic solid compounds, and microimaging of a model organism.

  18. 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.

  19. Site-assignment of 17O-NMR signals in itinerant metamagnetic compound Sr 3Ru 2O 7

    NASA Astrophysics Data System (ADS)

    Kitagawa, Kentaro; Ishida, Kenji; Perry, Robin S.; Maeno, Yoshiteru

    2006-05-01

    We have performed an 17O-NMR measurement in the bilayered perovskite ruthenate Sr 3Ru 2O 7 which shows itinerant metamagnetism at low temperatures. Three oxygen sites are identified in the 17O-NMR spectrum. NMR lines arising from the outer-apical O site are observable in the vicinity of a metamagnetic quantum critical point in spite of strong spin fluctuations. The field dependence of the Knight shift scales with the bulk magnetization.

  20. Estimation of the regional cerebral metabolic rate of oxygen consumption with proton detected 17O MRI during precision 17O2 inhalation in swine

    PubMed Central

    Mellon, Eric A.; Beesam, R. Shashank; Baumgardner, James E.; Borthakur, Arijitt; Witschey, Walter R.; Reddy, Ravinder

    2009-01-01

    Despite the importance of metabolic disturbances in many diseases, there are currently no clinically used methods for the detection of oxidative metabolism in vivo. To address this deficiency, 17O MRI techniques are scaled from small animals to swine as a large animal model of human inhalation and circulation. The hemispheric cerebral metabolic rate of oxygen consumption (CMRO2) is estimated in swine by detection of metabolically produced H217O by rapid T1ρ-weighted proton magnetic resonance imaging on a 1.5 Tesla clinical scanner. The 17O is delivered as oxygen gas by a custom, minimal-loss, precision-delivery breathing circuit and converted to H217O by oxidative metabolism. A model for gas arterial input is presented for the deeply breathing large animal. The arterial input function for recirculation of metabolic water is measured by arterial blood sampling and high field 17O spectroscopy. It is found that minimal metabolic water “wash-in” occurs before 60 seconds. A high temporal resolution pulse sequence is employed to measure CMRO2 during those 60 seconds after delivery begins. Only about one tidal volume of 17O enriched oxygen gas is used per measurement. Proton measurements of signal change due to metabolically produced water are correlated with 17O in vivo spectroscopy. Using these techniques, the hemispheric CMRO2 in swine is estimated to be 1.23 ± 0.26 μmol/g/min, consistent with existing literature values. All of the technology used to perform these CMRO2 estimates can easily be adapted to clinical MR scanners, and it is hoped that this work will lead to future studies of human disease. PMID:19428508

  1. Nuclear Magnetic Spin-Noise and Unusual Relaxation of Oxygen-17 in Water

    NASA Astrophysics Data System (ADS)

    Bendet-Taicher, Eli

    Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) have evolved into widely used techniques, providing diagnostic power in medicine and material sciences due to their high precision and non-invasive nature. Due to the small population differences between spin energy states, a significant sensitivity problem for NMR arises. The low sensitivity of NMR is probably its greatest limitation for applications to biological systems. An alternative probe tuning strategy based on the spin-noise response for application in standard one-dimensional and common high-resolution multidimensional standard biomolecular NMR experiments has shown an increase of up to 50% signal-to-noise (SNR) in one-dimensional NMR experiments and an increase of up to 22% in multi-dimensional ones. The method requires the adjustment of the optimal tuning condition, which may be offset by several hundreds kHz from the conventional tuning settings using the noise response of the water protons as an indicator. This work is described in the first part of the thesis (chapters 2--3). The second part (Chapter 4) of the thesis deals with anomalous oxygen-17 NMR relaxation behavior in water. Oxygen-17 (17O), which has spin of 5/2 and a natural abundance of 0.0373% possesses an electric quadrupole moment. Spin-lattice and spin-spin relaxation occur by the quadrupole interaction, while the J-coupling to 1H spins and exchange are deciding factors. T1 and T2 of 17O in water have been previously measured over a large range of temperatures. The spin-spin relaxation times of 17O as a function of temperature show an anomalous behaviour, expressed by a local maximum at the temperature of maximum density (TMD) of water. It is shown that the same anomalous behaviour shifts to the respective temperatures of maximum density for H2O/D2O solutions with different compositions and salt concentrations. This phenomenon can be correlated to the pH dependency of T2 of 17O in water, and water proton exchange rates

  2. On the Δ17O budget of atmospheric O2

    NASA Astrophysics Data System (ADS)

    Young, Edward D.; Yeung, Laurence Y.; Kohl, Issaku E.

    2014-06-01

    We modeled the Δ17O of atmospheric O2 using 27 ordinary differential equations comprising a box model composed of the stratosphere, troposphere, geosphere, hydrosphere and biosphere. Results show that 57% of the deficit in 17O in O2 relative to a reference water fractionation line is the result of kinetic isotope fractionation attending the Dole effect, 33% balances the positive Δ17O of O(1D) in the stratosphere, and 10% is from evapotranspiration. The predicted Δ‧17O O2 relative to waters is -0.410‰ as measured at the δ18O of air. The value for Δ‧17O O2 varies at fixed δ18O with the concentration of atmospheric CO2, gross primary production, and net primary production as well as with reaction rates in the stratosphere. Our model prediction is consistent with our measurements of the oxygen isotopic composition of air O2 compared with rocks if rocks define a fractionation line with an intercept in δ‧17O = 103ln(δ17O/103 + 1) vs. δ‧18O = 103ln(δ18O/103 + 1) space less than SMOW but more positive than some recent measurements imply. The predicted Δ17O is less negative than that obtained from recent measurements of O2 directly against SMOW. Underestimation of Δ‧17O O2 can only be ameliorated if the integrated (bulk) Δ‧17O for stratospheric CO2 is significantly greater than measurements currently allow. Our results underscore the need for high-precision comparisons of the 17O/16O and 18O/16O ratios of atmospheric O2, VSMOW, and rocks.

  3. 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)

  4. {sup 17}O NMR investigations of oxidative degradation in polymers

    SciTech Connect

    Alam, T.M.; Celina, M.; Assink, R.A.; Gillen, K.T.; Clough, R.L.

    1996-12-31

    We have initiated studies using both solution and solid state magic angle spinning {sup 17}O NMR for a series of oxidatively aged polymers. This short note reports the solution {sup 17}O NMR for oxidatively degraded polypropylene, ethylene-propylene-diene, polyisoprene, and nitrile rubber. Enriched O{sub 2} is used during the accelerated aging. 3 figs, 7 refs.

  5. Insight into protein nuclear magnetic resonance research.

    PubMed

    Stoven, V; Lallemand, J Y; Abergel, D; Bouaziz, S; Delsuc, M A; Ekondzi, A; Guittet, E; Laplante, S; Le Goas, R; Malliavin, T

    1990-08-01

    Nuclear magnetic resonance (NMR) is one of the most powerful techniques to investigate the geometry of molecules in solution. It has been widely applied, in recent years, to the study of protein conformation. However, full reconstruction of the 3-D structure of such macro-molecules, still constitutes a real challenge for the spectroscopist. Skills as diverse as biology, spectroscopy, signal processing, or computer sciences, are required. This paper presents various aspects of the research in that domain, and our contribution to it. PMID:2126458

  6. Treatment of scalar-relativistic effects on nuclear magnetic shieldings using a spin-free exact-two-component approach

    NASA Astrophysics Data System (ADS)

    Cheng, Lan; Gauss, Jürgen; Stanton, John F.

    2013-08-01

    A cost-effective treatment of scalar-relativistic effects on nuclear magnetic shieldings based on the spin-free exact-two-component theory in its one-electron variant (SFX2C-1e) is presented. The SFX2C-1e scheme gains its computational efficiency, in comparison to the four-component approach, from a focus on spin-free contributions and from the elimination of the small component. For the calculation of nuclear magnetic shieldings, the separation of spin-free and spin-dependent terms in the parent four-component theory is carried out here for the matrix representation of the Dirac equation in terms of a restricted-magnetically balanced gauge-including atomic orbital basis. The resulting spin-free four-component matrix elements required to calculate nuclear magnetic shieldings are then used to construct the corresponding SFX2C-1e Hamiltonian and its perturbed counterpart in the context of SFX2C-1e analytic derivative theory. To demonstrate the applicability of the approach, we report coupled-cluster calculations for prototypical problems such as the 17O shieldings of transition-metal oxo complexes (MO_4^{2-}, M = Cr, Mo, and W) and the 129Xe shieldings of xenon fluorides (XeF2, XeF4, and XeF6).

  7. Some Nuclear Techniques in Experimental Magnetism: Mössbauer Effect, Neutron Scattering and Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Piecuch, Michel

    The goal of this chapter is to present three traditional methods for the study of magnetic properties : Mössbauer effect, neutron diffraction and nuclear magnetic resonance. It begins by recalling the basic properties of atomic nuclei and describing the hyperfine interactions between the nucleus and its surrounding. Then, the recoilless absorption of γ-rays by crystal, the Mössbauer effect is presented, we discuss the main parameters measured and show one example of application. Next we present neutron interactions with matter, the interaction of neutrons with the atomic nucleus and the interaction of the neutron magnetic moment with the magnetic moment of electrons. The use of polarized neutron and the inelastic scattering of neutrons are also discussed. The comparison between neutron experiments and synchrotron radiation techniques is briefly reviewed. One example of the use of neutron scattering in the domain of thin film magnetism is shown. Finally, we present the basic theory of nuclear magnetic resonance and one application of this technique to the study of Co/Cu multilayers.

  8. Enrichment of H(2)(17)O from tap water, characterization of the enriched water, and properties of several (17)O-labeled compounds.

    PubMed

    Prasad, Brinda; Lewis, Andrew R; Plettner, Erika

    2011-01-01

    A low-abundance form of water, H(2)(17)O, was enriched from 0.04% to ∼90% by slow evaporation and fractional distillation of tap water. The density and refractive index for H(2)(17)O are reported. Gas chromatography-mass spectrometry (GC-MS) of (16)O- and (17)O-1-hexanols and their trimethyl silyl ethers and of (16)O- and (17)O-hexamethyl disiloxanes was used to determine the percentage of (17)O enrichment in the H(2)(17)O. Furthermore, the chemical shifts of labeled and nonlabeled water dissolved in CDCl(3) differed sufficiently that we could verify the enrichment of H(2)(17)O. (17)O hexanol was synthesized by the reaction of iodohexane with Na(17)OH. (17)O-Labeled trimethylsilanol and (17)O-labeled hexamethyldisiloxane were prepared by the reaction of H(2)(17)O with bis(trimethylsilyl)trifluoroacetamide (BSTFA). To generate standards for (17)O NMR, H(2)(17)O(2), and (17)O camphor were prepared. H(2)(17)O was electrolyzed to form (17)O-labeled hydrogen peroxide which was quantified using two colorimetric assays. (17)O-Labeled camphor was prepared by exchanging the ketone oxygen of camphor using H(2)(17)O. The (17)O-labeled compounds were characterized using (17)O, (1)H, and (13)C NMR and GC-MS. While we were characterizing the labeled camphor, we also detected an unexpected oxygen exchange reaction of primary alcohols, catalyzed by electrophilic ketones such as camphor. The reaction is a displacement of the alcohol OH group by water. This is an example of the usefulness of (17)O NMR in the study of a reaction mechanism that has not been noticed previously. PMID:21128590

  9. Explosive hydrogen burning of 17O in classical novae.

    PubMed

    Fox, C; Iliadis, C; Champagne, A E; Coc, A; José, J; Longland, R; Newton, J; Pollanen, J; Runkle, R

    2004-08-20

    We report on the observation of a new resonance at E(lab)(R)=190 keV in the 17O(p,gamma)18F reaction. The measured resonance strength amounts to omegagamma(pgamma)=(1.2+/-0.2)x10(-6) eV. With this new value, the uncertainties in the 17O(p,gamma)18F and 17O(p,alpha)14N thermonuclear reaction rates are reduced by orders of magnitude at nova temperatures. Our significantly improved reaction rates have major implications for the galactic synthesis of 17O, the stellar production of the radioisotope 18F, and the predicted oxygen isotopic ratios in nova ejecta. PMID:15447168

  10. Solid-State 17O NMR of Paramagnetic Coordination Compounds**

    PubMed Central

    Kong, Xianqi; Terskikh, Victor V.; Khade, Rahul L.; Yang, Liu; Rorick, Amber; Zhang, Yong; He, Peng; Huang, Yining; Wu, Gang

    2015-01-01

    We demonstrate that high-quality solid-state 17O (I = 5/2) NMR spectra can be successfully obtained for paramagnetic coordination compounds in which oxygen atoms are directly bonded to the paramagnetic metal centers. For complexes containing V(III) (S = 1), Cu(II) (S = 1/2), and Mn(III) (S = 2) metal centers, the 17O isotropic paramagnetic shifts were found to span a range of more than 10000 ppm. In several cases, high-resolution 17O NMR spectra were recorded under very fast magic-angle spinning (MAS) conditions at 21.1 T. Quantum chemical computations using density functional theory (DFT) qualitatively reproduced the experimental 17O hyperfine shift tensors. PMID:25694203

  11. Two-dimensional nuclear magnetic resonance petrophysics.

    PubMed

    Sun, Boqin; Dunn, Keh-Jim

    2005-02-01

    Two-dimensional nuclear magnetic resonance (2D NMR) opens a wide area for exploration in petrophysics and has significant impact to petroleum logging technology. When there are multiple fluids with different diffusion coefficients saturated in a porous medium, this information can be extracted and clearly delineated from CPMG measurements of such a system either using regular pulsing sequences or modified two window sequences. The 2D NMR plot with independent variables of T2 relaxation time and diffusion coefficient allows clear separation of oil and water signals in the rocks. This 2D concept can be extended to general studies of fluid-saturated porous media involving other combinations of two or more independent variables, such as chemical shift and T1/T2 relaxation time (reflecting pore size), proton population and diffusion contrast, etc. PMID:15833623

  12. In vivo nuclear magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Leblanc, A.; Evans, H.; Bryan, R. N.; Johnson, P.; Schonfeld, E.; Jhingran, S. G.

    1984-01-01

    A number of physiological changes have been demonstrated in bone, muscle and blood after exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long duration space missions is an important NASA goal. The advent of tomographic nuclear magnetic resonance imaging (NMR or MRI) gives NASA a way to greatly extend early studies of this phenomena in ways not previously possible; NMR is also noninvasive and safe. NMR provides both superb anatomical images for volume assessments of individual organs and quantification of chemical/physical changes induced in the examined tissues. The feasibility of NMR as a tool for human physiological research as it is affected by microgravity is demonstrated. The animal studies employed the rear limb suspended rat as a model of mucle atrophy that results from microgravity. And bedrest of normal male subjects was used to simulate the effects of microgravity on bone and muscle.

  13. Nuclear magnetic resonance imaging in medicine

    PubMed Central

    McKinstry, C S

    1986-01-01

    Using the technique of nuclear magnetic resonance (NMR, MR, MRI), the first images displaying pathology in humans were published in 1980.1 Since then, there has been a rapid extension in the use of the technique, with an estimated 225 machines in use in the USA at the end of 1985.2 Considerable enthusiasm has been expressed for this new imaging technique,3 although awareness of its high cost in the present economic climate has led to reservations being expressed in other quarters.2 The aim of this article is to give an outline of the present state of NMR, and indicate some possible future developments. ImagesFig 1Fig 2Fig 3(a)Fig 3 (b)Fig 4Fig 5Fig 6Fig 7 (a)Fig 7 (b)Fig 8Fig 9Fig 10 PMID:3811023

  14. [Nuclear magnetic resonance in ischemic cardiopathy].

    PubMed

    Meave, Aloha

    2007-01-01

    Nuclear magnetic resonance is the "gold standard" technique to quantify the ventricular volume, the ejection fraction, and the myocardial mass. In patients suffering from ischemic cardiopathy, the ejection fraction is the most important prognostic parameter, even above from lessoned arteries index. An adequate diagnose between a non-viable and a viable myocardium is of great importance in the therapeutic approach for ischemic cardiopathy. By administrating a paramagnetic contrast media named gadolinium, fist pass and late-reinforcement techniques, are applied. With these, it is possible to evaluate the perfusion as well as necrotic areas. In order to identify sub-endocardium ischemia, drugs such as adenosine and dipiridamol, are employed as vasodilators. This technique allows the definition of reinforcement extension, being sub-endocardiac, which is an ailment which affects 50% of the myocardium depth, or even, transmural compromise. PMID:18938717

  15. Nuclear magnetic resonance imaging of the spine

    SciTech Connect

    Modic, M.T.; Weinstein, M.A.; Pavlicek, W.; Starnes, D.L.; Duchesneau, P.M.; Boumphrey, F.; Hardy, R.J. Jr.

    1984-01-01

    Forty subjects were examined to determine the accuracy and clinical usefulness of nuclear magnetic resonance (NMR) examination of the spine. The NMR images were compared with plain radiographs, high-resolution computed tomograms, and myelograms. The study included 15 patients with normal spinal cord anatomy and 25 patients whose pathological conditions included canal stenosis, herniated discs, metastatic tumors, primary cord tumor, trauma, Chiari malformations, syringomyelia, and developmental disorders. Saturation recovery images were best in differentiating between soft tissue and cerebrospinal fluid. NMR was excellent for the evaluation of the foramen magnum region and is presently the modality of choice for the diagnosis of syringomyelia and Chiari malformation. NMR was accurate in diagnosing spinal cord trauma and spinal canal block.

  16. Geochemical Controls on Nuclear Magnetic Resonance Measurements

    SciTech Connect

    Knight, Rosemary; Prasad, Manika; Keating, Kristina

    2003-11-11

    OAK-B135 Our research objectives are to determine, through an extensive set of laboratory experiments, the effect of the specific mineralogic form of iron and the effect of the distribution of iron on proton nuclear magnetic resonance (NMR) relaxation mechanisms. In the first nine months of this project, we have refined the experimental procedures to be used in the acquisition of the laboratory NMR data; have ordered, and conducted preliminary measurements on, the sand samples to be used in the experimental work; and have revised and completed the theoretical model to use in this project. Over the next year, our focus will be on completing the first phase of the experimental work where the form and distribution of the iron in the sands in varied.

  17. Phosphorus 31 nuclear magnetic resonance examination of female reproductive tissues

    SciTech Connect

    Noyszewski, E.A.; Raman, J.; Trupin, S.R.; McFarlin, B.L.; Dawson, M.J. )

    1989-08-01

    Nuclear magnetic resonance spectroscopy is a powerful method of investigating the relationship between metabolism and function in living tissues. We present evidence that the phosphorus 31 spectra of myometrium and placenta are functions of physiologic state and gestational age. Specific spectroscopic abnormalities are observed in association with disorders of pregnancy and gynecologic diseases. Our results suggest that noninvasive nuclear magnetic resonance spectroscopy examinations may sometimes be a useful addition to magnetic resonance imaging examinations, and that nuclear magnetic resonance spectroscopy of biopsy specimens could become a cost-effective method of evaluating certain biochemical abnormalities.

  18. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The

  19. Dynamic nuclear polarization at high magnetic fields

    PubMed Central

    Maly, Thorsten; Debelouchina, Galia T.; Bajaj, Vikram S.; Hu, Kan-Nian; Joo, Chan-Gyu; Mak–Jurkauskas, Melody L.; Sirigiri, Jagadishwar R.; van der Wel, Patrick C. A.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe/γl), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (≥5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms—the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments. PMID:18266416

  20. Zeroth order regular approximation approach to parity violating nuclear magnetic resonance shielding tensors.

    PubMed

    Nahrwold, Sophie; Berger, Robert

    2009-06-01

    In this paper, a quasirelativistic two-component zeroth order regular approximation (ZORA) density functional theory (DFT) approach to the calculation of parity violating (PV) resonance frequency differences between the nuclear magnetic resonance (NMR) spectra of enantiomers is presented and the systematics of PV NMR shielding constants in C(2)-symmetric dihydrogen dichalcogenides (H(2)X(2) with X=(17)O, (33)S, (77)Se, (125)Te, (209)Po) are investigated. The typical sin(2alpha)-like dependence of the PV NMR frequency splittings on the dihedral angle alpha is observed for the entire series. As for the scaling behavior of the effect with the nuclear charge Z of X, the previously reported Z(2.5+/-0.5) scaling in the nonrelativistic limit is reproduced and a scaling of approximately Z(3) for the paramagnetic and Z(5) for the spin-orbit coupling contribution to the frequency splitting is observed in the relativistic framework. The paramagnetic and spin-orbit coupling contributions are typically of opposite sign for the molecular structures studied herein and the maximum scaling of the total ZORA frequency splitting (i.e., the sum of the two contributions) is Z(3.9) for H(2)Po(2). Thus, an earlier claim for a spin-orbit coupling contribution scaling with up to Z(7) for H(2)Po(2) and the erratic dihedral angle dependence obtained for this compound within a four-component Dirac-Hartree-Fock-Coulomb study is not confirmed at the DFT level. The maximum NMR frequency splitting reported here is of the order of 10 mHz for certain clamped conformations of H(2)Po(2) inside a static magnetic field with magnetic flux density of 11.7 T. Frequency splittings of this size have been estimated to be detectable with present day NMR spectrometers. Thus, a NMR route toward molecular PV appears promising once suitable compounds have been identified. PMID:19508050

  1. 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

    2016-04-01

    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. PMID:26964007

  2. Corrections for 17O interference, effects on Δ47 determination

    NASA Astrophysics Data System (ADS)

    Olack, G.; He, B.; Colman, A. S.

    2013-12-01

    The measurements of 13C on CO2 samples are routinely corrected for 17O contribution to the m/z 45 signal (Craig, 1957; Santrock, et al., 1985). The 17O abundance affects the Δ47 calculation, and the amount of 17O present is routinely determined using the relationship between 18O and 17O presented in IAEA TECDOC 825 (Dennis, et al., 2011; Huntington, et al., 2009; Gonfiantini, et al., 1995). In 2010, the IAEA released new recommendations for 17O determinations to be used for 13C corrections (Brand, et al., 2010). We compare the effect of using different ways to determine 17O interference, as well as using the currently accepted N(13C)/N(12C) value for VPDB (Brand, et al., 2010), on heated gas lines, model data, and on CO2 gases made to have similar δ47 and Δ47, but with highly contrasting δ18O and δ13C values. The 2010 IAEA recommendations give a better fit for heated gas data than the TECDOC 825 recommendations. Comparing differences in the data points relative to their respective fitted lines, we see differences on the order of 5 to 10 ppm in Δ47. That corresponds to a systematic error of 2 °C in the temperature estimate (room temperature range), and one that varies with δ13C and δ18O, but not necessarily with δ47. The preliminary work on equilibrated CO2 gases having similar δ47, but very different δ13C and δ18O, showed large (ca. 70 ppm) differences in Δ47 when using the (standard) TECDOC 825 recommendations. The Δ47 values were much closer when the 2010 IUPAC recommendations were used. This also serves as a test of the updated factors for 17O determination, as well as the overall robustness of the Δ47 measurement.

  3. Nuclear magnetic resonance spectrometric assay of beta-lactamase.

    PubMed Central

    Kono, M; O'Hara, K; Shiomi, Y

    1980-01-01

    Beta-Lactam antibiotics and the crude enzyme were mixed in deuterium oxide and placed in a nuclear magnetic resonance tube. The change of the nuclear magnetic resonance spectrum during the enzymatic reaction was then analyzed to determine beta-lactamase activity. By using beta-lactam antibiotics such as penicillins, cephalosporins, and cephamycins as substrates, a comparison of the beta-lactamase activities was made between the nuclear magnetic resonance spectrometric assay and the iodometric assay. There was a close correlation between these two methods. PMID:6986114

  4. Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

    SciTech Connect

    Paulsen, Jeffrey L; Franck, John; Demas, Vasiliki; Bouchard, Louis-S.

    2008-03-27

    Single-sided and mobile nuclear magnetic resonance (NMR) sensors have the advantages of portability, low cost, and low power consumption compared to conventional high-field NMR and magnetic resonance imaging (MRI) systems. We present fast, flexible, and easy-to-implement target field algorithms for mobile NMR and MRI magnet design. The optimization finds a global optimum ina cost function that minimizes the error in the target magnetic field in the sense of least squares. When the technique is tested on a ring array of permanent-magnet elements, the solution matches the classical dipole Halbach solution. For a single-sided handheld NMR sensor, the algorithm yields a 640 G field homogeneous to 16 100 ppm across a 1.9 cc volume located 1.5 cm above the top of the magnets and homogeneous to 32 200 ppm over a 7.6 cc volume. This regime is adequate for MRI applications. We demonstrate that the homogeneous region can be continuously moved away from the sensor by rotating magnet rod elements, opening the way for NMR sensors with adjustable"sensitive volumes."

  5. Nuclear magnetic resonance imaging of the kidney

    SciTech Connect

    Hricak, H.; Crooks, L.; Sheldon, P.; Kaufman, L.

    1983-02-01

    The role of nuclear magnetic resonance (NMR) imaging of the kidney was analyzed in 18 persons (6 normal volunteers, 3 patients with pelvocaliectasis, 2 with peripelvic cysts, 1 with renal sinus lipomatosis, 3 with renal failure, 1 with glycogen storage disease, and 2 with polycystic kidney disease). Ultrasound and/or computed tomography (CT) studies were available for comparison in every case. In the normal kidney distinct anatomical structures were clearly differentiated by NMR. The best anatomical detail ws obtained with spin echo (SE) imaging, using a pulse sequence interval of 1,000 msec and an echo delay time of 28 msec. However, in the evaluation of normal and pathological conditions, all four intensity images (SE 500/28, SE 500/56, SE 1,000/28, and SE 1,000/56) have to be analyzed. No definite advantage was found in using SE imaging with a pulse sequence interval of 1,500 msec. Inversion recovery imaging enhanced the differences between the cortex and medulla, but it had a low signal-to-noise level and, therefore, a suboptimal overall resolution. The advantages of NMR compared with CT and ultrasound are discussed, and it is concluded that NMR imaging will prove to be a useful modality in the evaluation of renal disease.

  6. Selectivity in multiple quantum nuclear magnetic resonance

    SciTech Connect

    Warren, W.S.

    1980-11-01

    The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible.

  7. 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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    The set of 1:1 and 2:1 complexes of XOOX' (X, X' = H, CH3) 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 17O nucleus in each compound. Additional calculations for 1H 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 × 108 V m-1 should be applied to observe a shift of ≈1 ppm for 17O magnetic shielding in the proposed set of complexes.

  8. 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. PMID:21932885

  9. Nuclear magnetization in gallium arsenide quantum dots at zero magnetic field

    PubMed Central

    Sallen, G.; Kunz, S.; Amand, T.; Bouet, L.; Kuroda, T.; Mano, T.; Paget, D.; Krebs, O.; Marie, X.; Sakoda, K.; Urbaszek, B.

    2014-01-01

    Optical and electrical control of the nuclear spin system allows enhancing the sensitivity of NMR applications and spin-based information storage and processing. Dynamic nuclear polarization in semiconductors is commonly achieved in the presence of a stabilizing external magnetic field. Here we report efficient optical pumping of nuclear spins at zero magnetic field in strain-free GaAs quantum dots. The strong interaction of a single, optically injected electron spin with the nuclear spins acts as a stabilizing, effective magnetic field (Knight field) on the nuclei. We optically tune the Knight field amplitude and direction. In combination with a small transverse magnetic field, we are able to control the longitudinal and transverse components of the nuclear spin polarization in the absence of lattice strain—that is, in dots with strongly reduced static nuclear quadrupole effects, as reproduced by our model calculations. PMID:24500329

  10. Nuclear Magnetic Double Resonance Using Weak Perturbing RF Fields

    ERIC Educational Resources Information Center

    Reynolds, G. Fredric

    1977-01-01

    Describes a nuclear magnetic resonance experimental example of spin tickling; also discusses a direct approach for verifying the relative signs of coupling constants in three-spin cyclopropyl systems. (SL)

  11. Nuclear magnetic resonance spectroscopy with single spin sensitivity

    PubMed Central

    Müller, C.; Kong, X.; Cai, J.-M.; Melentijević, K.; Stacey, A.; Markham, M.; Twitchen, D.; Isoya, J.; Pezzagna, S.; Meijer, J.; Du, J. F.; Plenio, M. B.; Naydenov, B.; McGuinness, L. P.; Jelezko, F.

    2014-01-01

    Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen–vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four 29Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds. PMID:25146503

  12. Nuclear magnetic resonance spectroscopy with single spin sensitivity.

    PubMed

    Müller, C; Kong, X; Cai, J-M; Melentijević, K; Stacey, A; Markham, M; Twitchen, D; Isoya, J; Pezzagna, S; Meijer, J; Du, J F; Plenio, M B; Naydenov, B; McGuinness, L P; Jelezko, F

    2014-01-01

    Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen-vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four (29)Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds. PMID:25146503

  13. Study of the soft dipole modes in 140Ce via inelastic scattering of 17O

    NASA Astrophysics Data System (ADS)

    Krzysiek, M.; Kmiecik, M.; Maj, A.; Bednarczyk, P.; Ciemała, M.; Fornal, B.; Grȩbosz, J.; Mazurek, K.; Mȩczyński, W.; Ziȩbliński, M.; Crespi, F. C. L.; Bracco, A.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Giaz, A.; Leoni, S.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Vandone, V.; Wieland, O.; De Angelis, G.; Napoli, D. R.; Valiente-Dobon, J. J.; Bazzacco, D.; Farnea, E.; Gottardo, A.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Michelagnoli, C.; Recchia, F.; Ur, C.; Gadea, A.; Huyuk, T.; Barrientos, D.; Birkenbach, B.; Geibel, K.; Hess, H.; Reiter, P.; Steinbach, T.; Wiens, A.; Bürger, A.; Görgen, A.; Guttormsen, M.; Larsen, A. C.; Siem, S.

    2014-05-01

    The main aim of this study was a deeper understanding of the nuclear structure properties of the soft dipole modes in 140Ce, excited via inelastic scattering of weakly bound 17O projectiles. An important aim was to investigate the ‘splitting’ of the PDR into two parts: a low-energy isoscalar component dominated by neutron-skin oscillations and a higher-energy component lying on the tail of the giant dipole resonance of a rather isovector character. This was already observed for this nucleus, investigated in (α, α‧) and (γ, γ‧) experiments. The experiment was performed at Laboratori Nazionali di Legnaro, Italy. Inelastic scattering of 17O ion beam at 20 MeV A-1 was used to excite the resonance modes in the 140Ce target. Gamma-rays were registered by five triple clusters of AGATA-Demonstrator and nine large volume scintillators (LaBr3). The scattered 17O ions were identified by two ΔE - E Si telescopes of the TRACE array mounted inside the scattering chamber. The telescopes consisted of two segmented Si-pad detectors, each of 60 pixels. Very preliminary data have shown a strong domination of the E1 transitions in the ‘pygmy’ region with a character more similar to the one obtained in alpha scattering experiment.

  14. High-Resolution Nuclear Magnetic Resonance of Solids.

    ERIC Educational Resources Information Center

    Maciel, Gary E.

    1984-01-01

    Examines recent developments in techniques for obtaining high-resolution nuclear magnetic resonance (NMR) spectra on solid samples, discussing the kinds of applications for which these techniques are well suited. Also discusses the characteristics of NMR of solids and generating magnetization for NMR in solids. (JN)

  15. 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)

  16. Electron Paramagnetic Resonance -- Nuclear Magnetic Resonance Three Axis Vector Magnetometer

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Clark, Philip; Griffith, Robert; Larsen, Michael; Mirijanian, James

    2012-06-01

    The Northrop Grumman Corporation is leveraging the technology developed for the Nuclear Magnetic Resonance Gyroscope (NMRG) to build a combined Electron Paramagnetic Resonance -- Nuclear Magnetic Resonance (EPR-NMR) magnetometer. The EPR-NMR approach provides a high bandwidth and high sensitivity simultaneous measurement of all three vector components of the magnetic field averaged over the small volume of the sensor's one vapor cell. This poster will describe the history, operational principles, and design basics of the EPR-NMR magnetometer including an overview of the NSD designs developed and demonstrated to date. General performance results will also be presented.

  17. Desktop fast-field cycling nuclear magnetic resonance relaxometer.

    PubMed

    Sousa, Duarte Mesquita; Marques, Gil Domingos; Cascais, José Manuel; Sebastião, Pedro José

    2010-07-01

    In this paper a new type of Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometer with low power consumption (200W) and cycle to cycle field stability better than 10(-4) is described. The new high-permeability magnet was designed to allow for good magnetic field homogeneity and allows for the sample rotation around an axis perpendicular to magnetic field, operating with magnetic fields between 0 and 0.21T. The power supply of the new relaxometer was specially developed in order to have steady state accurate currents and allow for magnetic field switching times less than 3ms. Additional control circuits were developed and included to compensate the Earth magnetic field component parallel to the field axis and to compensate for parasitic currents. The main aspects of the developed circuits together with some calibrating experimental results using the liquid crystal compounds 5CB and 8CB are presented and discussed. PMID:20688489

  18. Comparison of nuclear electric resonance and nuclear magnetic resonance in integer and fractional quantum Hall states

    SciTech Connect

    Tomimatsu, Toru Shirai, Shota; Hashimoto, Katsushi Sato, Ken; Hirayama, Yoshiro

    2015-08-15

    Electric-field-induced nuclear resonance (NER: nuclear electric resonance) involving quantum Hall states (QHSs) was studied at various filling factors by exploiting changes in nuclear spins polarized at quantum Hall breakdown. Distinct from the magnetic dipole interaction in nuclear magnetic resonance, the interaction of the electric-field gradient with the electric quadrupole moment plays the dominant role in the NER mechanism. The magnitude of the NER signal strongly depends on whether electronic states are localized or extended. This indicates that NER is sensitive to the screening capability of the electric field associated with QHSs.

  19. Effective Giromagnetic Ratios in Artifical Nuclear Magnetization Pumping of the Noble Gases Mix

    NASA Astrophysics Data System (ADS)

    Popov, E. N.; Barantsev, K. A.; Litvinov, A. N.

    2015-09-01

    Dynamic of the nuclear magnetization of the two noble gases mix was studied in this research. Nuclear magnetization pumped along the induction of external magnetic field. Vector of nuclear magnetization is given a tilt by the week rotational magnetic field, which makes NMR for noble gases. Interaction between the nuclear magnetic moments of the different noble gases adducted to shifts at the frequency of nuclear moments precession in external magnetic field. Effective gyromagnetic ratios of the nuclear of noble gases is defined and it different from the tabulated value. There is theoretical calculation of effective gyromagnetic ratios in this research.

  20. Magnet design considerations for Fusion Nuclear Science Facility

    DOE PAGESBeta

    Zhai, Yuhu; Kessel, Chuck; El-guebaly, Laila; Titus, Peter

    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

  1. Nuclear magnetic resonance in optimally-doped YBCO and the electronic phases of bilayer graphene

    NASA Astrophysics Data System (ADS)

    Throckmorton, Robert E.

    We treat two different problems in condensed matter physics. The first concerns nuclear magnetic resonance (NMR) in optimally-doped YBCO in the mixed state. We show that the line shape is broadened due to the fact that the Knight shift becomes position-dependent in the mixed state. We also identify a second mechanism, in which a pair of spin up quasiparticles is emitted or absorbed, by which the nuclear spins can relax in the presence of a magnetic field, and show that this second mechanism dominates at low temperatures. We then compare our results to experimental data on 17O NMR and show that it is possible to explain the data without invoking the presence of antiferromagnetic correlations in the vortex cores. In fact, we show that the effects of such correlations on the 17O relaxation rates are suppressed in the mixed state, as they are in the normal state. The second problem concerns the electronic phases of bilayer graphene at half filling. Using finite-temperature weak-coupling RG methods, we are able to analytically determine all possible outcomes of the RG flow equations for the nine coupling constants. From this, we are able to determine all of the possible leading instabilities that the system may exhibit as its temperature is lowered. We find that the full phase diagram exhibits a very rich structure, with many different possible instabilities. We then specialize to the case of finite range density-density interactions. We introduce such an interaction into the microscopic tight-binding model and show how it can be related to the coupling constants in the lowenergy effective theory, and apply these results to determine the leading instabilities of the system as a function of the range of the interaction. We consider two forms of the interaction, both motivated by experimental setups, namely a potential like that produced by an electron in the presence of an infinite conducting plate, and like that produced by an electron situated exactly halfway between

  2. Hydrogen Burning of {sup 17}O in Classical Novae

    SciTech Connect

    Chafa, A.; Ouichaoui, S.; Tatischeff, V.; Coc, A.; Garrido, F.; Kiener, J.; Lefebvre-Schuhl, A.; Thibaud, J.-P.; Aguer, P.; Barhoumi, S.; Hernanz, M.; Jose, J.; Sereville, N. de

    2005-07-15

    We report on the observation of a previously unknown resonance at E{sub R}{sup lab}=194.1{+-}0.6 keV in the {sup 17}O(p,{alpha}){sup 14}N reaction, with a measured resonance strength {omega}{gamma}{sub p{alpha}}=1.6{+-}0.2 meV. We studied in the same experiment the {sup 17}O(p,{gamma}){sup 18}F reaction by an activation method and the resonance-strength ratio was found to be {omega}{gamma}{sub p{alpha}}/{omega}{gamma}{sub p{gamma}}=470{+-}50. The corresponding excitation energy in the {sup 18}F compound nucleus was determined to be 5789.8{+-}0.3 keV by {gamma}-ray measurements using the {sup 14}N({alpha},{gamma}){sup 18}F reaction. These new resonance properties have important consequences for {sup 17}O nucleosynthesis and {gamma}-ray astronomy of classical novae.

  3. High-nuclearity magnetic clusters: Magnetic interactions in clusters encapsulated by molecular metal oxides

    NASA Astrophysics Data System (ADS)

    Borras-Almenar, Juan José; Coronado, Eugenio; Galan-Mascaros, Jose Ramón; Gómez-García, Carlos J.

    1995-02-01

    The ability of the molecular metal oxides derived from the Keggin anion [PW 12O 40] 3- to accommodate magnetic ions at specific sites, giving rise to polymetallic clusters with increasing spin nuclearities is discussed. Examples of magnetic clusters with three, four and nine metal ions exhibiting ferromagnetic exchange couplings or a coexistence of ferro- and antiferromagnetic couplings are reported.

  4. Local nuclear magnetic resonance spectroscopy with giant magnetic resistance-based sensors

    NASA Astrophysics Data System (ADS)

    Guitard, P. A.; Ayde, R.; Jasmin-Lebras, G.; Caruso, L.; Pannetier-Lecoeur, M.; Fermon, C.

    2016-05-01

    Nuclear Magnetic Resonance (NMR) spectroscopy on small volumes, either on microfluidic channels or in vivo configuration, is a present challenge. We report here a high resolution NMR spectroscopy on micron scale performed with Giant Magnetic Resistance-based sensors placed in a static magnetic B 0 field of 0.3 T. The sensing volume of the order of several tens of pL opens the way to high resolution spectroscopy on volumes unreached so far.

  5. 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.

  6. 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.

  7. In vivo nuclear magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Leblanc, A.

    1986-05-01

    During the past year the Woodlands Baylor Magnetic Resonance Imaging (MRI) facility became fully operational. A detailed description of this facility is given. One significant instrument addition this year was the 100 MHz, 40cm bore superconducting imaging spectrometer. This instrument gives researchers the capability to acquire high energy phosphate spectra. This will be used to investigate ATP, phosphocreatinine and inorganic phosphate changes in normal and atrophied muscle before, during and after exercise. An exercise device for use within the bore of the imaging magnet is under design/construction. The results of a study of T sub 1 and T sub 2 changes in atrophied muscle in animals and human subjects are given. The imaging and analysis of the lower leg of 15 research subjects before and after 5 weeks of complete bedrest was completed. A compilation of these results are attached.

  8. In vivo nuclear magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Leblanc, A.

    1986-01-01

    During the past year the Woodlands Baylor Magnetic Resonance Imaging (MRI) facility became fully operational. A detailed description of this facility is given. One significant instrument addition this year was the 100 MHz, 40cm bore superconducting imaging spectrometer. This instrument gives researchers the capability to acquire high energy phosphate spectra. This will be used to investigate ATP, phosphocreatinine and inorganic phosphate changes in normal and atrophied muscle before, during and after exercise. An exercise device for use within the bore of the imaging magnet is under design/construction. The results of a study of T sub 1 and T sub 2 changes in atrophied muscle in animals and human subjects are given. The imaging and analysis of the lower leg of 15 research subjects before and after 5 weeks of complete bedrest was completed. A compilation of these results are attached.

  9. Magnetic field simulation of magnetic phase detection sensor for steam generator tube in nuclear power plants

    NASA Astrophysics Data System (ADS)

    Ryu, Kwon-sang; Son, Derac; Park, Duck-gun; Kim, Yong-il

    2010-05-01

    Magnetic phases and defects are partly produced in steam generator tubes by stress and heat, because steam generator tubes in nuclear power plants are used under high temperature, high pressure, and radioactivity. The magnetic phases induce an error in the detection of the defects in steam generator tubes by the conventional eddy current method. So a new method is needed for detecting the magnetic phases in the steam generator tubes. We designed a new U-type yoke which has two kinds of coils and simulated the signal by the magnetic phases and defects in the Inconnel 600 tube.

  10. Concepts in Biochemistry: Nuclear Magnetic Resonance Spectroscopy in Biochemistry.

    ERIC Educational Resources Information Center

    Cheatham, Steve

    1989-01-01

    Discusses the nature of a nuclear magnetic resonance (NMR) experiment, the techniques used, the types of structural and dynamic information obtained, and how one can view and refine structures using computer graphics techniques in combination with NMR data. Provides several spectra and a computer graphics image from B-form DNA. (MVL)

  11. 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.

  12. 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…

  13. Nuclear magnetic resonance implementation of a quantum clock synchronization algorithm

    SciTech Connect

    Zhang Jingfu; Long, G.C; Liu Wenzhang; Deng Zhiwei; Lu Zhiheng

    2004-12-01

    The quantum clock synchronization (QCS) algorithm proposed by Chuang [Phys. Rev. Lett. 85, 2006 (2000)] has been implemented in a three qubit nuclear magnetic resonance quantum system. The time difference between two separated clocks can be determined by measuring the output states. The experimental realization of the QCS algorithm also demonstrates an application of the quantum phase estimation.

  14. Nuclear Magnetic Resonance Coupling Constants and Electronic Structure in Molecules.

    ERIC Educational Resources Information Center

    Venanzi, Thomas J.

    1982-01-01

    Theory of nuclear magnetic resonance spin-spin coupling constants and nature of the three types of coupling mechanisms contributing to the overall spin-spin coupling constant are reviewed, including carbon-carbon coupling (neither containing a lone pair of electrons) and carbon-nitrogen coupling (one containing a lone pair of electrons).…

  15. Study of {sup 17}O(p,{alpha}){sup 14}N reaction via the Trojan Horse Method for application to {sup 17}O nucleosynthesis

    SciTech Connect

    Sergi, M. L.; Spitaleri, C.; Pizzone, R. G.; Gulino, M.; Cherubini, S.; Crucilla, V.; La Cognata, M.; Lamia, L.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Tudisco, S.; Tumino, A.; Coc, A.; Hammache, F.; Sereville, N. de; Kiss, G.

    2008-05-21

    Because of the still present uncertainties on its rate, the {sup 17}O(p,{alpha}){sup 14}N is one of the most important reaction to be studied in order to get more information about the fate of {sup 17}O in different astrophysical scenarios. The preliminary study of the three-body reaction {sup 2}H({sup 17}O,{alpha}{sup 14}N)n is presented here as a first stage of the indirect study of this important {sup 17}O(p,{alpha}){sup 14}N reaction through the Trojan Horse Method (THM)

  16. Influence of nuclear spin on chemical reactions: Magnetic isotope and magnetic field effects (A Review)

    PubMed Central

    Turro, Nicholas J.

    1983-01-01

    The course of chemical reactions involving radical pairs may depend on occurrence and orientation of nuclear spins in the pairs. The influence of nuclear spins is maximized when the radical pairs are confined to a space that serves as a cage that allows a certain degree of independent diffusional and rotational motion of the partners of the pair but that also encourages reencounters of the partners within a period which allows the nuclear spins to operate on the odd electron spins of the pair. Under the proper conditions, the nuclear spins can induce intersystem crossing between triplet and singlet states of radical pairs. It is shown that this dependence of intersystem crossing on nuclear spin leads to a magnetic isotope effect on the chemistry of radical pairs which provides a means of separating isotopes on the basis of nuclear spins rather than nuclear masses and also leads to a magnetic field effect on the chemistry of radical pairs which provides a means of influencing the course of polymerization by the application of weak magnetic fields. PMID:16593273

  17. 1- and 2+ discrete states in 90Zr populated via the (17O,'17Oγ ) reaction

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Bracco, A.; Nicolini, R.; Lanza, E. G.; Vitturi, A.; Mengoni, D.; Leoni, S.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Corsi, A.; Giaz, A.; Million, B.; Pellegri, L.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemała, M.; Kmiecik, M.; Krzysiek, M.; Maj, A.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; Cederwall, B.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Hess, H.; Isocrate, R.; Jolie, J.; Jungclaus, A.; Kempley, R. S.; Labiche, M.; Menegazzo, R.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Sahin, E.; Siem, S.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.

    2015-02-01

    2+ and 1- states in 90Zr were populated via the (17O,'17Oγ ) reaction at 340 MeV. The γ decay was measured with high resolution using the AGATA (advanced γ tracking array demonstrator array). Differential cross sections were obtained at few different angles for the scattered particle. The results of the elastic scattering and inelastic excitation of 2+,3-, and 1- states are compared with distorted-wave Born approximation (DWBA) calculations, using both the standard collective form factor and a form factor obtained by folding microscopically calculated transition densities. This allowed to extract the isoscalar component of the 1- state at 6.424 MeV. The comparison of the present (17O,'17Oγ ) data with existing (γ ,γ' ) and (p ,p' ) data in the corresponding region of the γ continuum (6-11 MeV), characterized by a large E 1 component, shows completely different behaviors of the cross section as a function of the nuclear excitation energy. The comparison of the data with DWBA calculations suggests a decrease of the isoscalar strength in the cross section with increasing excitation energy.

  18. Nuclear magnetic resonance imaging at microscopic resolution

    NASA Astrophysics Data System (ADS)

    Johnson, G. Allan; Thompson, Morrow B.; Gewalt, Sally L.; Hayes, Cecil E.

    Resolution limits in NMR imaging are imposed by bandwidth considerations, available magnetic gradients for spatial encoding, and signal to noise. This work reports modification of a clinical NMR imaging device with picture elements of 500 × 500 × 5000 μm to yield picture elements of 50 × 50 × 1000 μm. Resolution has been increased by using smaller gradient coils permitting gradient fields >0.4 mT/cm. Significant improvements in signal to noise are achieved with smaller rf coils, close attention to choice of bandwidth, and signal averaging. These improvements permit visualization of anatomical structures in the rat brain with an effective diameter of 1 cm with the same definition as is seen in human imaging. The techniques and instrumentation should open a number of basic sciences such as embryology, plant sciences, and teratology to the potentials of NMR imaging.

  19. Nuclear magnetic resonance studies of biological systems

    SciTech Connect

    Antypas, W.G. Jr.

    1988-01-01

    The difference between intracellular and extracellular proton relaxation rates provides the basis for the determination of the mean hemoglobin concentration (MHC) in red blood cells. The observed water T{sub 1} relaxation data from red blood cell samples under various conditions were fit to the complete equation for the time-dependent decay of magnetization for a two-compartment system including chemical exchange. The MHC for each sample was calculated from the hematocrit and the intracellular water fraction as determined by NMR. The binding of the phosphorylcholine (PC) analogue, 2-(trimethylphosphonio)-ethylphosphate (phosphoryl-phosphocholine, PPC) to the PC binding myeloma proteins TEPC-15, McPC 603, and MOPC 167 was studied by {sup 31}P NMR.

  20. A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

    NASA Astrophysics Data System (ADS)

    Martel, L.; Somers, J.; Berkmann, C.; Koepp, F.; Rothermel, A.; Pauvert, O.; Selfslag, C.; Farnan, I.

    2013-05-01

    A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (˜10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th1-xUx)O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first 17O MAS-NMR measurements on NpO2+x samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.

  1. Nuclear magnetic resonance imaging in patients with cardiac pacing devices.

    PubMed

    Buendía, Francisco; Sánchez-Gómez, Juan M; Sancho-Tello, María J; Olagüe, José; Osca, Joaquín; Cano, Oscar; Arnau, Miguel A; Igual, Begoña

    2010-06-01

    Currently, nuclear magnetic resonance imaging is contraindicated in patients with a pacemaker or implantable cardioverter-defibrillator. This study was carried out because the potential risks in this situation need to be clearly defined. This prospective study evaluated clinical and electrical parameters before and after magnetic resonance imaging was performed in 33 patients (five with implantable cardioverter-defibrillators and 28 with pacemakers). In these patients, magnetic resonance imaging was considered clinically essential. There were no clinical complications. There was a temporary communication failure in two cases, sensing errors during imaging in two cases, and a safety signal was generated in one pacemaker at the maximum magnetic resonance frequency and output level. There were no technical restrictions on imaging nor were there any permanent changes in the performance of the cardiac pacing device. PMID:20515632

  2. Unconventional nuclear magnetic resonance techniques using nanostructured diamond surfaces

    NASA Astrophysics Data System (ADS)

    Acosta, Victor; Jarmola, Andrey; Budker, Dmitry; Santori, Charles; Huang, Zhihong; Beausoleil, Raymond

    2014-03-01

    Nuclear magnetic resonance (NMR) technologies rely on obtaining high nuclear magnetization, motivating low operating temperatures and high magnetic fields. Dynamic nuclear polarization (DNP) techniques traditionally require another superconducting magnet and THz optics. We seek to use chip-scale devices to polarize nuclei in liquids at room temperature. The technique relies on optical pumping of nitrogen-vacancy (NV) centers and subsequent transfer of polarization to nuclei via hyperfine interaction, spin diffusion, and heteronuclear polarization transfer. We expect efficient polarization transfer will be realized by maximizing the diamond surface area. We have fabricated densely-packed (50 % packing fraction), high-aspect-ratio (10+) nanopillars over mm2 regions of the diamond surface. Pillars designed to have a few-hundred-nanometer diameter act as optical antennas, reducing saturation intensity. We also report progress in using nanopillar arrays as sensitive optical detectors of nano-scale NMR by measuring NV center Zeeman shifts produced by nearby external nuclei. The enhanced surface area increases the effective density of NV centers which couple to external nuclei. Combining these techniques may enable, e.g., identification of trace analytes and molecular imaging.

  3. Enhanced Nuclear Magnetism: Some Novel Features and Prospective Experiments

    NASA Astrophysics Data System (ADS)

    Abragam, A.; Bleaney, B.

    1983-06-01

    This review of enhanced nuclear magnetism discusses a number of features not previously considered, with special reference to new experiments that use dynamic methods to produce high nuclear polarization, followed by adiabatic demagnetization in the rotating frame (a.d.r.f.) to produce nuclear ordered states that may be investigated by the scattering of beams of neutrons. Section 2. The 'enhancement' of the nuclear moment arises from the electronic magnetization M_I induced through the hyperfine interaction. It is shown that the spatial distribution of M_I is the same as that of M_H, the Van Vleck magnetization induced by an external field, provided that J is a good quantum number. The spatial distributions are not in general the same in Russell-Saunders coupling, e.g. in the 3d group. Section 3. The Bloch equations are extended to include anisotropic nuclear moments. Section 4. The 'truncated' spin Hamiltonian is derived for spin-spin interaction between enhanced moments. Section 5. A general cancellation theorem for second-order processes in spin-lattice relaxation is derived, showing that the intrinsic direct process must be of third order. The relaxation rate obeys an equation similar to that for Kramers electronic ions, but reduced as the fifth power of the resonance frequencies. The relaxation rates observed experimentally (except in very high fields) are ascribed to paramagnetic impurities, so that these can be used to produce dynamic nuclear polarization (d.n.p.). Section 6. The interactions of neutrons with the true nuclear moment μ_I, the Van Vleck moment M_H, the 'pseudonuclear' moment M_I and the 'pseudomagnetic' nuclear moment μ *_I are discussed. It is shown that the four contributions can be observed separately by measurement of the form factor for neutron scattering as a function of temperature and direction of the applied magnetic field. Precession of the neutron spin in the 'pseudomagnetic' field H* is discussed with reference to the case of Ho

  4. Long-lived nuclear spin states far from magnetic equivalence.

    PubMed

    Stevanato, Gabriele; Roy, Soumya Singha; Hill-Cousins, Joe; Kuprov, Ilya; Brown, Lynda J; Brown, Richard C D; Pileio, Giuseppe; Levitt, Malcolm H

    2015-02-28

    Clusters of coupled nuclear spins may form long-lived nuclear spin states, which interact weakly with the environment, compared to ordinary nuclear magnetization. All experimental demonstrations of long-lived states have so far involved spin systems which are close to the condition of magnetic equivalence, in which the network of spin-spin couplings is conserved under all pair exchanges of symmetry-related nuclei. We show that the four-spin system of trans-[2,3-(13)C2]-but-2-enedioate exhibits a long-lived nuclear spin state, even though this spin system is very far from magnetic equivalence. The 4-spin long-lived state is accessed by slightly asymmetric chemical substitutions of the centrosymmetric molecular core. The long-lived state is a consequence of the locally centrosymmetric molecular geometry for the trans isomer, and is absent for the cis isomer. A general group theoretical description of long-lived states is presented. It is shown that the symmetries of coherent and incoherent interactions are both important for the existence of long-lived states. PMID:25633837

  5. 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.

  6. Nuclear magnetic resonance and transcutaneous electromagnetic blood flow measurement.

    PubMed

    Battocletti, J H; Halbach, R E; Salles-Cunha, S X; Sances, A

    1983-09-01

    Static and alternating magnetic fields are employed in blood flowmeters using nuclear magnetic resonance (NMR) principles and electromagnetic induction by a moving conductor (TEM). Both techniques require high steady magnetic fields, obtained either from permanent magnets or from electromagnets. A relatively homogeneous magnetic field is needed for NMR, but, though important for calibration, homogeneity is not critical for TEM. NMR is more complex than TEM since it requires radio-frequency and audio-frequency magnetic fields. However, the TEM method requires surface electrodes in contact with the skin, or needle electrodes placed subcutaneously, whereas NMR is contactless. The NMR flowmeter can be calibrated directly, but appropriate and approximate models must be assumed and then solved by computer to quantify blood flow by the TEM flowmeter. Flow in individual vessels is measured a priori in the TEM flowmeter by virtue of the assumed models. To measure flow in individual vessels by NMR, a scanning or ranging method is required, which logically leads to blood flow imaging. The levels of steady, radio-frequency, and audio-frequency magnetic fields used in the two types of flowmeters are low enough so as not to cause any apparent stimulus to human volunteers and patients tested. PMID:6228667

  7. Algorithmic cooling in liquid-state nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Atia, Yosi; Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2016-01-01

    Algorithmic cooling is a method that employs thermalization to increase qubit purification level; namely, it reduces the qubit system's entropy. We utilized gradient ascent pulse engineering, an optimal control algorithm, to implement algorithmic cooling in liquid-state nuclear magnetic resonance. Various cooling algorithms were applied onto the three qubits of C132-trichloroethylene, cooling the system beyond Shannon's entropy bound in several different ways. In particular, in one experiment a carbon qubit was cooled by a factor of 4.61. This work is a step towards potentially integrating tools of NMR quantum computing into in vivo magnetic-resonance spectroscopy.

  8. Nuclear magnetic resonance in environmental engineering: principles and applications.

    PubMed

    Lens, P N; Hemminga, M A

    1998-01-01

    This paper gives an introduction to nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI) in relation to applications in the field of environmental science and engineering. The underlying principles of high resolution solution and solid state NMR, relaxation time measurements and imaging are presented. Then, the use of NMR is illustrated and reviewed in studies of biodegradation and biotransformation of soluble and solid organic matter, removal of nutrients and xenobiotics, fate of heavy metal ions, and transport processes in bioreactor systems. PMID:10335581

  9. Optical pumping in solid state nuclear magnetic resonance

    SciTech Connect

    Tycko, R.; Reimer, J.A.

    1996-08-01

    An important current trend in solid state nuclear magnetic resonance (NMR) is the growing exploitation of optical pumping of nuclear spin polarizations as a means of enhancing and localizing NMR signals. Recent work has been concentrated in two areas, namely optically pumped NMR in semiconductors and optical pumping of noble gases. Progress in these two areas, including technical developments and new applications in physical chemistry, condensed matter physics, and biomedical sciences, is reviewed. Likely directions for future developments are suggested. 58 refs., 13 figs.

  10. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Yang, Jian; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2015-04-07

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  11. Electronic Magnetization of a Quantum Point Contact Measured by Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Kawamura, Minoru; Ono, Keiji; Stano, Peter; Kono, Kimitoshi; Aono, Tomosuke

    2015-07-01

    We report an electronic magnetization measurement of a quantum point contact (QPC) based on nuclear magnetic resonance (NMR) spectroscopy. We find that NMR signals can be detected by measuring the QPC conductance under in-plane magnetic fields. This makes it possible to measure, from Knight shifts of the NMR spectra, the electronic magnetization of a QPC containing only a few electron spins. The magnetization changes smoothly with the QPC potential barrier height and peaks at the conductance plateau of 0.5 ×2 e2/h . The observed features are well captured by a model calculation assuming a smooth potential barrier, supporting a no bound state origin of the 0.7 structure.

  12. Nuclear magnetic resonance spectroscopy of the circadian clock of cyanobacteria.

    PubMed

    Chang, Yong-Gang; Tseng, Roger; Kuo, Nai-Wei; LiWang, Andy

    2013-07-01

    The most well-understood circadian clock at the level of molecular mechanisms is that of cyanobacteria. This overview is on how solution-state nuclear magnetic resonance (NMR) spectroscopy has contributed to this understanding. By exciting atomic spin-½ nuclei in a strong magnetic field, NMR obtains information on their chemical environments, inter-nuclear distances, orientations, and motions. NMR protein samples are typically aqueous, often at near-physiological pH, ionic strength, and temperature. The level of information obtainable by NMR depends on the quality of the NMR sample, by which we mean the solubility and stability of proteins. Here, we use examples from our laboratory to illustrate the advantages and limitations of the technique. PMID:23667047

  13. Relativistic effects on the nuclear magnetic shielding tensor

    NASA Astrophysics Data System (ADS)

    Melo, J. I.; Ruiz de Azua, M. C.; Giribet, C. G.; Aucar, G. A.; Romero, R. H.

    2003-01-01

    A new approach for calculating relativistic corrections to the nuclear magnetic shieldings is presented. Starting from a full relativistic second order perturbation theory expression a two-component formalism is constructed by transforming matrix elements using the elimination of small component scheme and separating out the contributions from the no-virtual pair and the virtual pair part of the second order corrections to the energy. In this way we avoid a strong simplification used previously in the literature. We arrive at final expressions for the relativistic corrections which are equivalent to those of Fukui et al. [J. Chem Phys. 105, 3175 (1996)] and at some other additional terms correcting both the paramagnetic and the diamagnetic part of the nuclear magnetic shielding. Results for some relativistic corrections to the shieldings of the heavy and light nuclei in HX and CH3X (X=Br,I) at both random phase and second order polarization propagator approach levels are given.

  14. Probing soil and aquifer material porosity with nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Hinedi, Z. R.; Kabala, Z. J.; Skaggs, T. H.; Borchardt, D. B.; Lee, R. W. K.; Chang, A. C.

    1993-12-01

    Nuclear magnetic resonance relaxation measurements were used to identify different characteristic porosity domains in soil and aquifer materials. The porosity distribution can be inferred from these measurements by a regularization method applicable to any nuclear magnetic resonance (NMR) relaxation, or by an analytic method applicable only to multiexponential relaxations (D. Orazio et al., 1989). The porosity distribution obtained from NMR relaxation measurements strongly depends on the pore shape factor. For the Borden aquifer material, both the regularized and the analytic pore size distribution obtained from NMR relaxation measurements are consistent with those obtained by Ball et al. (1990) using Hg porosimetry and N2 adsorption. For the Eustis and the Webster soils, the measured porosity domains are qualitatively consistent with those expected based on their respective composition. Our findings suggest that due to the long time required to saturate fine pores, NMR measurements of porosity distribution that are collected at short saturation times are biased toward larger pore sizes.

  15. Nuclear magnetic and quadrupole resonance studies of the stripes materials

    NASA Astrophysics Data System (ADS)

    Grafe, H.-J.

    2012-11-01

    Nuclear Magnetic and Quadrupole Resonance (NMR/NQR) is a powerful tool to probe electronic inhomogeneities in correlated electron systems. Its local character allows for probing different environments due to spin density modulations or inhomogeneous doping distributions emerging from the correlations in these systems. In fact, NMR/NQR is not only sensitive to magnetic properties through interaction of the nuclear spin, but also allows to probe the symmetry of the charge distribution and its homogeneity, as well as structural modulations, through sensitivity to the electric field gradient (EFG). We review the results of NMR and NQR in the cuprates from intrinsic spatial variations of the hole concentration in the normal state to stripe order at low temperatures, thereby keeping in mind the influence of doping induced disorder and inhomogeneities. Finally, we briefly discuss NQR evidence for local electronic inhomogeneities in the recently discovered iron pnictides, suggesting that electronic inhomogeneities are a common feature of correlated electron systems.

  16. Nuclear chiral and magnetic rotation in covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Zhao, Pengwei

    2016-05-01

    Excitations of chiral rotation observed in triaxial nuclei and magnetic and/or antimagnetic rotations (AMR) seen in near-spherical nuclei have attracted a lot of attention. Unlike conventional rotation in well-deformed or superdeformed nuclei, here the rotational axis is not necessary coinciding with any principal axis of the nuclear density distribution. Thus, tilted axis cranking (TAC) is mandatory to describe these excitations self-consistently in the framework of covariant density functional theory (CDFT). We will briefly introduce the formalism of TAC–CDFT and its application for magnetic and AMR phenomena. Configuration-fixed CDFT and its predictions for nuclear chiral configurations and for favorable triaxial deformation parameters are also presented, and the discoveries of the multiple chiral doublets in 133Ce and 103Rh are discussed.

  17. Chemometric Analysis of Nuclear Magnetic Resonance Spectroscopy Data

    SciTech Connect

    ALAM,TODD M.; ALAM,M. KATHLEEN

    2000-07-20

    Chemometric analysis of nuclear magnetic resonance (NMR) spectroscopy has increased dramatically in recent years. A variety of different chemometric techniques have been applied to a wide range of problems in food, agricultural, medical, process and industrial systems. This article gives a brief review of chemometric analysis of NMR spectral data, including a summary of the types of mixtures and experiments analyzed with chemometric techniques. Common experimental problems encountered during the chemometric analysis of NMR data are also discussed.

  18. Dispersion and Aggregation of Magnetic Nanoparticles for Nuclear Waste Separation

    NASA Astrophysics Data System (ADS)

    Han, H.; Singh, M. Kaur T.; Qiang, Y.; Johnson, A.; Paszczynski, A.

    2009-05-01

    A novel method of nuclear waste separation using conjugates of actinide chelators and magnetic nanoparticles (MNPs) is developed. The fast separation can be facilitated by the high magnetic moments of core-shell MNPs. Highly uniform dispersion of MNPs in solutions is required for the efficient conjugation. However, stabilization of well dispersed MNPs hinders fast magnetic collection of the conjugates. To address this dilemma, the dispersion and aggregation of the MNPs has been investigated in both mechanical and chemical approaches. In the mechanical approach, continuous ultrasonic dispersed the MNPs, whereas they re-aggregated after up to 20 minutes treatment. Bead beating method improved the MNPs' suspension time by up to two factors. Nevertheless, the magnetization of MNPs dropped sharply due to the generation of non-magnetic beads' residual. Chemical method using electrolyte and agents with different polarizations had significant effects on the suspension and aggregation of the various sized MNPs. The fine balance of Van de Waals, Brownian forces, magnetic dipole and Coulomb interactions are discussed.

  19. Magnetic Flux Compression Concept for Nuclear Pulse Propulsion and Power

    NASA Technical Reports Server (NTRS)

    Litchford, Ronald J.

    2000-01-01

    The desire for fast, efficient interplanetary transport requires propulsion systems having short acceleration times and very high specific impulse attributes. Unfortunately, most highly efficient propulsion systems which are within the capabilities of present day technologies are either very heavy or yield very low impulse such that the acceleration time to final velocity is too long to be of lasting interest, One exception, the nuclear thermal thruster, could achieve the desired acceleration but it would require inordinately large mass ratios to reach the range of desired final velocities. An alternative approach, among several competing concepts that are beyond our modern technical capabilities, is a pulsed thermonuclear device utilizing microfusion detonations. In this paper, we examine the feasibility of an innovative magnetic flux compression concept for utilizing microfusion detonations, assuming that such low yield nuclear bursts can be realized in practice. In this concept, a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stationary structure formed from a high temperature superconductor (HTSC). In general, we are interested in accomplishing two important functions: (1) collimation of a hot diamagnetic plasma for direct thrust production; and (2) pulse power generation for dense plasma ignition. For the purposes of this research, it is assumed that rnicrofusion detonation technology may become available within a few decades, and that this approach could capitalize on recent advances in inertial confinement fusion ICF) technologies including magnetized target concepts and antimatter initiated nuclear detonations. The charged particle expansion velocity in these detonations can be on the order of 10 (exp 6)- 10 (exp 7) meters per second, and, if effectively collimated by a magnetic nozzle, can yield the Isp and the acceleration levels needed for practical interplanetary spaceflight. The ability to ignite pure

  20. Quantitative velocity distributions via nuclear magnetic resonance flow metering

    NASA Astrophysics Data System (ADS)

    O'Neill, Keelan T.; Fridjonsson, Einar O.; Stanwix, Paul L.; Johns, Michael L.

    2016-08-01

    We demonstrate the use of Tikhonov regularisation as a data inversion technique to determine the velocity distributions of flowing liquid streams. Regularisation is applied to the signal produced by a nuclear magnetic resonance (NMR) flow measurement system consisting of a pre-polarising permanent magnet located upstream of an Earth's magnetic field NMR detection coil. A simple free induction decay (FID) NMR signal is measured for the flowing stream in what is effectively a 'time-of-flight' measurement. The FID signal is then modelled as a function of fluid velocity and acquisition time, enabling determination of the velocity probability distributions via regularisation. The mean values of these velocity distributions were successfully validated against in-line rotameters. The ability to quantify multi-modal velocity distributions was also demonstrated using a two-pipe system.

  1. Nuclear magnetic resonance imaging with hyper-polarized noble gases

    SciTech Connect

    Schmidt, D.M.; George, J.S.; Penttila, S.I.; Caprihan, A.

    1997-10-01

    This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The nuclei of noble gases can be hyper polarized through a laser-driven spin exchange to a degree many orders of magnitude larger than that attainable by thermal polarization without requiring a strong magnetic field. The increased polarization from the laser pumping enables a good nuclear magnetic resonance (NMR) signal from a gas. The main goal of this project was to demonstrate diffusion-weighted imaging of such hyper-polarized noble gas with magnetic resonance imaging (MRI). Possible applications include characterizing porosity of materials and dynamically imaging pressure distributions in biological or acoustical systems.

  2. Quantitative velocity distributions via nuclear magnetic resonance flow metering.

    PubMed

    O'Neill, Keelan T; Fridjonsson, Einar O; Stanwix, Paul L; Johns, Michael L

    2016-08-01

    We demonstrate the use of Tikhonov regularisation as a data inversion technique to determine the velocity distributions of flowing liquid streams. Regularisation is applied to the signal produced by a nuclear magnetic resonance (NMR) flow measurement system consisting of a pre-polarising permanent magnet located upstream of an Earth's magnetic field NMR detection coil. A simple free induction decay (FID) NMR signal is measured for the flowing stream in what is effectively a 'time-of-flight' measurement. The FID signal is then modelled as a function of fluid velocity and acquisition time, enabling determination of the velocity probability distributions via regularisation. The mean values of these velocity distributions were successfully validated against in-line rotameters. The ability to quantify multi-modal velocity distributions was also demonstrated using a two-pipe system. PMID:27343484

  3. Theory and computation of nuclear magnetic resonance parameters.

    PubMed

    Vaara, Juha

    2007-10-28

    The art of quantum chemical electronic structure calculation has over the last 15 years reached a point where systematic computational studies of magnetic response properties have become a routine procedure for molecular systems. One of their most prominent areas of application are the spectral parameters of nuclear magnetic resonance (NMR) spectroscopy, due to the immense importance of this experimental method in many scientific disciplines. This article attempts to give an overview on the theory and state-of-the-art of the practical computations in the field, in terms of the size of systems that can be treated, the accuracy that can be expected, and the various factors that would influence the agreement of even the most accurate imaginable electronic structure calculation with experiment. These factors include relativistic effects, thermal effects, as well as solvation/environmental influences, where my group has been active. The dependence of the NMR spectra on external magnetic and optical fields is also briefly touched on. PMID:17925967

  4. New Versions of Terahertz Radiation Sources for Dynamic Nuclear Polarization in Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bratman, V. L.; Kalynov, Yu. K.; Makhalov, P. B.; Fedotov, A. E.

    2014-01-01

    Dynamic nuclear polarization in strong-field nuclear magnetic resonance (NMR) spectroscopy requires terahertz radiation with moderate power levels. Nowadays, conventional gyrotrons are used almost exclusively to generate such radiation. In this review paper, we consider alternative variants of electronic microwave oscillators which require much weaker magnetic fields for their operation, namely, large-orbit gyrotrons operated at high cyclotron-frequency harmonics and Čerenkov-type devices, such as a backward-wave oscillator and a klystron frequency multiplier with tubular electron beams. Additionally, we consider the possibility to use the magnetic field created directly by the solenoid of an NMR spectrometer for operation of both the gyrotron and the backward-wave oscillator. Location of the oscillator in the spectrometer magnet makes it superfluous to use an additional superconducting magnet creating a strong field, significantly reduces the length of the radiation transmission line, and, in the case of Čerenkov-type devices, allows one to increase considerably the output-signal power. According to our calculations, all the electronic devices considered are capable of ensuring the power required for dynamic nuclear polarization (10 W or more) at a frequency of 260 GHz, whereas the gyrotrons, including their versions proposed in this paper, remain a single option at higher frequencies.

  5. Covalency in La2CuO4: A study of 17O hyperfine couplings in the paramagnetic phase

    NASA Astrophysics Data System (ADS)

    Walstedt, R. E.; Cheong, S.-W.

    2001-07-01

    17O nuclear magnetic resonance spectra from single crystals of La2CuO4 are reported for temperatures ranging from 285 to 800 K. Hyperfine tensor data for the planar sites are analyzed using a spin Hamiltonian model that includes spin-orbit coupling effects. The results show a 7.7% hybridization effect of the oxygen 2pσ orbital from a single copper neighbor, in good agreement with recent density-functional (DF) calculations by Hüsser et al. (HSSM). A large, positive isotropic shift component is also reported, presumably originating from the contact interaction with a hybridized 2s orbital component. First-order quadrupolar-splitting data lead to complete characterization of the electric-field gradient (EFG) tensor, which varies only slightly with temperature up to 800 K. EFG tensors for both doped and undoped La2CuO4 are fitted with a two-component model, which incorporates a substantial anisotropy in for the 2pσ wave functions, an effect that originated in the DF calculations of HSSM. This analysis reveals an increased charge density on the planar oxygens for the superconducting phase, in accord with the original Zhang-Rice model. However, the increase is found to correspond to only ~80% of the nominal doped-hole density, corroborating a similar conclusion reached recently by Hammel et al. Regarding the anomalous spin HF interaction reported in a previous paper for the weakly ferromagnetic state, the present results show that its effects extend all the way to and slightly beyond the orthorhombic-tetragonal phase boundary (TO-T~=550 K). Further, the predominant 2s contact HF interaction reported here supports the notion, suggested earlier, that a 2s admixture underlies the anomaly. However, the basic mechanism of the anomaly remains obscure.

  6. Analysis of ringing due to magnetic core materials used in pulsed nuclear magnetic resonance applications

    NASA Astrophysics Data System (ADS)

    Prabhu Gaunkar, Neelam; Nlebedim, Cajetan; Hadimani, Ravi; Bulu, Irfan; Song, Yi-Qiao; Mina, Mani; Jiles, David

    Oil-field well logging instruments employ pulsed nuclear magnetic resonance (NMR) techniques and use inductive sensors to detect and evaluate the presence of particular fluids in geological formations. Acting as both signal transmitters and receivers most inductive sensors employ magnetic cores to enhance the quality and amplitude of signals recorded during field measurements. It is observed that the magnetic core also responds to the applied input signal thereby generating a signal (`ringing') that interferes with the measurement of the signals from the target formations. This causes significant noise and receiver dead time and it is beneficial to eliminate/suppress the signals received from the magnetic core. In this work a detailed analysis of the magnetic core response and in particular loading of the sensor due to the presence of the magnetic core is presented. Pulsed NMR measurements over a frequency band of 100 kHz to 1MHz are used to determine the amplitude and linewidth of the signals acquired from different magnetic core materials. A lower signal amplitude and a higher linewidth are vital since these would correspond to minimal contributions from the magnetic core to the inductive sensor response and thus leading to minimized receiver dead time.

  7. Stray-field nuclear magnetic resonance imaging in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Garrido, Leoncio; Sampayo, José

    2008-03-01

    Magnetic levitation has been proposed as an alternative approach to simulate on Earth microgravity conditions encountered in space, allowing the investigation of weightlessness on materials and biological systems. In general, very strong magnetic fields, 15T or higher, are required to achieve levitation for a majority of diamagnetic substances. Here, we show that it is possible to achieve levitation of these substances in a commercial superconductive magnet operating with a nuclear magnetic resonance (NMR) spectrometer at 9.4T at ambient conditions. Furthermore, stray-field proton NMR imaging is performed in situ at the location where a sample is levitating, showing that it is feasible to obtain the corresponding one-dimensional profile. Considering that water is a diamagnetic substance and the main constituent of living systems, the outlined approach could be useful to investigate alterations in water proton NMR properties induced by low gravity and magnetic forces upon levitating, e.g., seeds, cells, etc. In addition to protons, it would also be possible to observe other nuclei (e.g., F19, P31, etc.) that may be of interest in metabolic and therapeutic investigations.

  8. Simulation of the diurnal variations of the isotope anomaly (?17O) of reactive trace gases (NOx, HOx) and implications for the ?17O of nitrate.

    NASA Astrophysics Data System (ADS)

    Morin, Samuel; Sander, Rolf; Savarino, Joël.

    2010-05-01

    The isotope anomaly of secondary atmospheric species such as nitrate (NO3-) has potential to provide useful constrains on their formation pathways. Indeed, the ?17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero ?17O in the atmosphere. Interpreting variations of ?17O in nitrate requires an in-depth understanding of the ?17O of its precursors taking into account non-linear chemical regimes operating under various environmental settings. In addition, the role of isotope exchange reactions must be carefully accounted for. To investigate the relevance of various assessments of the isotopic signature of nitrate production pathways that have recently been proposed in the literature, an atmospheric chemistry box model (MECCA, Sander et al., 2005, ACP)) was used to explicitly compute the diurnal variations of the isotope anomaly of NOx, HOx under several conditions prevailing in the marine boundary layer. ?17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation applied at each time step of the model (30 seconds typically). The model confirms that diurnal variations in ?17O of NOx are well predicted by the photochemical steady-state relationship introduced by Michalski et al. (2003, GRL) during the day, but that at night a different approach must be employed (e.g. « fossilization » of the ?17O of NOx as soon as the photochemical lifetime of NOx drops below ca. 5 minutes). The model also allows to evaluate the impact on ?17O of NOx and nitrate of the frequently made simplifying assumption that ?17O(HOx)=0 permil, with and without mass-independent fractionation during the H+O2-HO2 reaction. Recommendations for the modeling of ?17O of nitrate will be given, based on the extensive model work carried out. In addition, the link between diurnal variations of the ?17O of nitrate precursors and seasonal

  9. Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates

    SciTech Connect

    Chafa, A.; Ouichaoui, S.; Tatischeff, V.; Coc, A.; Garrido, F.; Kiener, J.; Lefebvre-Schuhl, A.; Thibaud, J.-P.; Aguer, P.; Barhoumi, S.; Hernanz, M.; Jose, J.; Sereville, N. de

    2007-03-15

    The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reactions are of major importance to hydrogen-burning nucleosynthesis in a number of different stellar sites. In particular, {sup 17}O and {sup 18}F nucleosynthesis in classical novae is strongly dependent on the thermonuclear rates of these two reactions. The previously estimated rate for {sup 17}O(p,{alpha}){sup 14}N carries very large uncertainties in the temperature range of classical novae (T=0.01-0.4 GK), whereas a recent measurement has reduced the uncertainty of the {sup 17}O(p,{gamma}){sup 18}F rate. We report on the observation of a previously undiscovered resonance at E{sub c.m.}=183.3 keV in the {sup 17}O(p,{alpha}){sup 14}N reaction, with a measured resonance strength {omega}{gamma}{sub p{alpha}}=(1.6{+-}0.2)x10{sup -3} eV. We studied in the same experiment the {sup 17}O(p,{gamma}){sup 18}F reaction by an activation method, and the resonance strength was found to amount to {omega}{gamma}{sub p{gamma}}=(2.2{+-}0.4)x10{sup -6} eV. The excitation energy of the corresponding level in {sup 18}F was determined to be 5789.8{+-}0.3 keV in a Doppler shift attenuation method measurement, which yielded a value of {tau}<2.6 fs for the level lifetime. The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates were calculated using the measured resonance properties and reconsidering some previous analyses of the contributions of other levels or processes. The {sup 17}O(p,{alpha}){sup 14}N rate is now well established below T=1.5 GK, with uncertainties reduced by orders of magnitude in the temperature range T=0.1-0.4 GK. The uncertainty in the {sup 17}O(p,{gamma}){sup 18}F rate is somewhat larger because of remaining obscurities in the knowledge of the direct capture process. These new resonance properties have important consequences for {sup 17}O nucleosynthesis and {gamma}-ray emission of classical novae.

  10. Chemometric Analysis of Two Dimensional Decay Data: Application to {sup 17}O NMR Relaxation Matrices

    SciTech Connect

    Alam, M.K.; Alam, T.M.

    1999-03-18

    The use of {sup 17}O NMR spectroscopy as a tool to investigate aging in polymer systems has recently been demonstrated. Because the natural abundance of {sup 17}O is extremely low (0.037%), the use of labeled {sup 17}O{sub 2} during the oxidation of polymers produces {sup 17}O NMR spectra whose signals arise entirely from the degradation species (i.e. signals from the bulk or unaged material are not observed). This selective isotopic labeling eliminates the impact of interference from the unaged material, cause (1) above. As discussed by Alam et al. spectral overlap between different degradation species as well as errors in quantification remains a major difficulty in {sup 17}O NMR spectroscopy. As a demonstration of the DECRA and CTBSA methods, relaxation matrices obtained from {sup 17}O NMR for model alcohol systems are evaluated. The benefits and limitations of these newly developed chemometric techniques are discussed.

  11. Tracing atmospheric nitrate deposition in a complex semiarid ecosystem using delta17O.

    PubMed

    Michalski, Greg; Meixner, Thomas; Fenn, Mark; Hernandez, Larry; Sirulnik, Abby; Allen, Edith; Thiemens, Mark

    2004-04-01

    The isotopic composition of nitrate collected from aerosols, fog, and precipitation was measured and found to have a large 17O anomaly with delta17O values ranging from 20 percent per thousand to 30% percent per thousand (delta17O = delta17O - 0.52(delta18O)). This 17O anomaly was used to trace atmospheric deposition of nitrate to a semiarid ecosystem in southern California. We demonstrate that the delta17O signal is a conserved tracer of atmospheric nitrate deposition and is a more robust indicator of N deposition relative to standard delta18O techniques. The data indicate that a substantial portion of nitrate found in the local soil, stream, and groundwater is of atmospheric origin and does not undergo biologic processing before being exported from the system. PMID:15112822

  12. Detection of molecules and cells using nuclear magnetic resonance with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Rümenapp, Christine; Gleich, Bernhard; Mannherz, Hans Georg; Haase, Axel

    2015-04-01

    For the detection of small molecules, proteins or even cells in vitro, functionalised magnetic nanoparticles and nuclear magnetic resonance measurements can be applied. In this work, magnetic nanoparticles with the size of 5-7 nm were functionalised with antibodies to detect two model systems of different sizes, the protein avidin and Saccharomyces cerevisiae as the model organism. The synthesised magnetic nanoparticles showed a narrow size distribution, which was determined using transmission electron microscopy and dynamic light scattering. The magnetic nanoparticles were functionalised with the according antibodies via EDC/NHS chemistry. The binding of the antigen to magnetic nanoparticles was detected through the change in the NMR T2 relaxation time at 0.5 T (≈21.7 MHz). In case of a specific binding the particles cluster and the T2 relaxation time of the sample changes. The detection limit in buffer for FITC-avidin was determined to be 1.35 nM and 107 cells/ml for S. cerevisiae. For fluorescent microscopy the avidin molecules were labelled with FITC and for the detection of S. cerevisiae the magnetic nanoparticles were additionally functionalised with rhodamine. The binding of the particles to S. cerevisiae and the resulting clustering was also seen by transmission electron microscopy.

  13. 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.

  14. 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.

  15. Experimental Study of 17O(p,{alpha})14N and 17O(p,{gamma})18F for Classical Nova Nucleosynthesis

    SciTech Connect

    Chafa, A.; Ouichaoui, S.; Tatischeff, V.; Coc, A.; Garrido, F.; Kiener, J.; Lefebvre-Schuhl, A.; Thibaud, J.-P.; Aguer, P.; Barhoumi, S.; Hernanz, M.; Jose, J.; Sereville, N. de

    2006-04-26

    We investigated the proton-capture reactions on 17O occurring in classical nova explosions. We observed a previously undiscovered resonance at E{sub R}{sup lab}=194.1{+-}0.6 keV in the 17O(p,{alpha})14N reaction, with a measured resonance strength {omega}{gamma}p{alpha}=1.6{+-}0.2 meV. We studied in the same experiment the 17O(p,{gamma})18F reaction by an activation method and the resonance-strength ratio was found to be {omega}{gamma}p{alpha}/{omega}{gamma}p{gamma}=470{+-}50. The corresponding excitation energy in the 18F compound nucleus was determined to be 5789.8{+-}0.3 keV by {gamma}-ray measurements using the 14N({alpha},{gamma})18F reaction. These new resonance properties have important consequences for 17O nucleosynthesis and {gamma}-ray astronomy of classical novae.

  16. Dynamical magnetic and nuclear polarization in complex spin systems: semi-magnetic II-VI quantum dots

    NASA Astrophysics Data System (ADS)

    Abolfath, Ramin M.; Trojnar, Anna; Roostaei, Bahman; Brabec, Thomas; Hawrylak, Pawel

    2013-06-01

    Dynamical magnetic and nuclear polarization in complex spin systems is discussed on the example of transfer of spin from exciton to the central spin of magnetic impurity in a quantum dot in the presence of a finite number of nuclear spins. The exciton is described in terms of electron and heavy-hole spins interacting via exchange interaction with magnetic impurity, via hyperfine interaction with a finite number of nuclear spins and via dipole interaction with photons. The time evolution of the exciton, magnetic impurity and nuclear spins is calculated exactly between quantum jumps corresponding to exciton radiative recombination. The collapse of the wavefunction and the refilling of the quantum dot with a new spin-polarized exciton is shown to lead to the build up of magnetization of the magnetic impurity as well as nuclear spin polarization. The competition between electron spin transfer to magnetic impurity and to nuclear spins simultaneous with the creation of dark excitons is elucidated. The technique presented here opens up the possibility of studying optically induced dynamical magnetic and nuclear polarization in complex spin systems.

  17. Measurement of δ18O, δ17O, and 17O-excess in water by off-axis integrated cavity output spectroscopy and isotope ratio mass spectrometry.

    PubMed

    Berman, Elena S F; Levin, Naomi E; Landais, Amaelle; Li, Shuning; Owano, Thomas

    2013-11-01

    Stable isotopes of water have long been used to improve understanding of the hydrological cycle, catchment hydrology, and polar climate. Recently, there has been increasing interest in measurement and use of the less-abundant (17)O isotope in addition to (2)H and (18)O. Off-axis integrated cavity output spectroscopy (OA-ICOS) is demonstrated for accurate and precise measurements δ(18)O, δ(17)O, and (17)O-excess in liquid water. OA-ICOS involves no sample conversion and has a small footprint, allowing measurements to be made by researchers collecting the samples. Repeated (514) high-throughput measurements of the international isotopic reference water standard Greenland Ice Sheet Precipitation (GISP) demonstrate the precision and accuracy of OA-ICOS: δ(18)OVSMOW-SLAP = -24.74 ± 0.07‰ (1σ) and δ(17)OVSMOW-SLAP = -13.12 ± 0.05‰ (1σ). For comparison, the International Atomic Energy Agency (IAEA) value for δ(18)OVSMOW-SLAP is -24.76 ± 0.09‰ (1σ) and an average of previously reported values for δ(17)OVSMOW-SLAP is -13.12 ± 0.06‰ (1σ). Multiple (26) high-precision measurements of GISP provide a (17)O-excessVSMOW-SLAP of 23 ± 10 per meg (1σ); an average of previously reported values for (17)O-excessVSMOW-SLAP is 22 ± 11 per meg (1σ). For all these OA-ICOS measurements, precision can be further enhanced by additional averaging. OA-ICOS measurements were compared with two independent isotope ratio mass spectrometry (IRMS) laboratories and shown to have comparable accuracy and precision as the current fluorination-IRMS techniques in δ(18)O, δ(17)O, and (17)O-excess. The ability to measure accurately δ(18)O, δ(17)O, and (17)O-excess in liquid water inexpensively and without sample conversion is expected to increase vastly the application of δ(17)O and (17)O-excess measurements for scientific understanding of the water cycle, atmospheric convection, and climate modeling among others. PMID:24032448

  18. 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.

  19. 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.

  20. Measurement of heat transfer coefficients by nuclear magnetic resonance.

    PubMed

    Gultekin, David H; Gore, John C

    2008-11-01

    We demonstrate an experimental method for the measurement of heat transfer coefficient for a fluid system by magnetic resonance imaging. In this method, the temporal variation of thermally induced nuclear shielding is monitored and the average heat transfer coefficient is measured as a function of fluid velocity. We examine the cases of natural convection and forced convection at fluid velocity up to 0.8 m s(-1). These cases correspond to low dimensionless Biot (Bi) number where the heat transfer is limited by thermal convection. We demonstrate the NMR method for two simple geometries, a cylinder and a sphere, to experimentally determine the heat transfer coefficient (h) in two NMR imaging and spectroscopy systems through measuring three NMR parameters, the chemical shift, magnetization and spin self diffusion coefficient. PMID:18524523

  1. Nuclear magnetic resonance tomography with a toroid cavity detector

    SciTech Connect

    Woelk, K.; Rathke, J.W.; Klingler, R.J.

    1995-02-01

    A new type of nuclear magnetic resonance (NMR) tomography has been developed at Argonne National Laboratory. The method uses the strong radio frequency field gradient within a cylindrical toroid cavity to provide high-resolution NMR spectral information while simultaneously resolving distances on the micron scale. The toroid cavity imaging technique differs from conventional magnetic resonance imaging (MRI) in that NMR structural information is not lost during signal processing. The new technique could find a wide range of applications in the characterization of surface layers and in the production of advanced materials. Potential areas of application include in situ monitoring of growth sites during ceramic formation processes, analysis of the oxygen annealing step for wires coated with high-temperature superconducting films, and investigation of the reaction chemistry as a function of distance within the diffusion layer for electrochemical processes.

  2. A personal computer-based nuclear magnetic resonance spectrometer

    NASA Astrophysics Data System (ADS)

    Job, Constantin; Pearson, Robert M.; Brown, Michael F.

    1994-11-01

    Nuclear magnetic resonance (NMR) spectroscopy using personal computer-based hardware has the potential of enabling the application of NMR methods to fields where conventional state of the art equipment is either impractical or too costly. With such a strategy for data acquisition and processing, disciplines including civil engineering, agriculture, geology, archaeology, and others have the possibility of utilizing magnetic resonance techniques within the laboratory or conducting applications directly in the field. Another aspect is the possibility of utilizing existing NMR magnets which may be in good condition but unused because of outdated or nonrepairable electronics. Moreover, NMR applications based on personal computer technology may open up teaching possibilities at the college or even secondary school level. The goal of developing such a personal computer (PC)-based NMR standard is facilitated by existing technologies including logic cell arrays, direct digital frequency synthesis, use of PC-based electrical engineering software tools to fabricate electronic circuits, and the use of permanent magnets based on neodymium-iron-boron alloy. Utilizing such an approach, we have been able to place essentially an entire NMR spectrometer console on two printed circuit boards, with the exception of the receiver and radio frequency power amplifier. Future upgrades to include the deuterium lock and the decoupler unit are readily envisioned. The continued development of such PC-based NMR spectrometers is expected to benefit from the fast growing, practical, and low cost personal computer market.

  3. Magnetic imaging: a new tool for UK national nuclear security.

    PubMed

    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

  4. 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

  5. Nuclear-magnetic-resonance quantum calculations of the Jones polynomial

    SciTech Connect

    Marx, Raimund; Spoerl, Andreas; Pomplun, Nikolas; Schulte-Herbrueggen, Thomas; Glaser, Steffen J.; Fahmy, Amr; Kauffman, Louis; Lomonaco, Samuel; Myers, John M.

    2010-03-15

    The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for a small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots.

  6. 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

  7. A highly integrated FPGA-based nuclear magnetic resonance spectrometer

    NASA Astrophysics Data System (ADS)

    Takeda, Kazuyuki

    2007-03-01

    The digital circuits required for a nuclear magnetic resonance (NMR) spectrometer, including a pulse programmer, a direct digital synthesizer, a digital receiver, and a PC interface, have been built inside a single chip of the field-programmable gate-array (FPGA). By combining the FPGA chip with peripheral analog components, a compact, laptop-sized homebuilt spectrometer has been developed, which is capable of a rf output of up to 400 MHz with amplitude-, phase-, frequency-, and pulse-modulation. The number of rf channels is extendable up to three without further increase in size.

  8. Nuclear Magnetic Resonance Applications to Unconventional Fossil Fuel Resources

    NASA Astrophysics Data System (ADS)

    Kleinberg, R. L.; Leu, G.

    2008-12-01

    Technical and economic projections strongly suggest that fossil fuels will continue to play a dominant role in the global energy market through at least the mid twenty-first century. However, low-cost conventional oil and gas will be depleted in that time frame. Therefore new sources of energy will be needed. We discuss two relatively untapped unconventional fossil fuels: heavy oil and gas hydrate. In both cases, nuclear magnetic resonance plays a key role in appraising the resource and providing information needed for designing production processes.

  9. 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.

  10. Light nuclear charge measurement with Alpha Magnetic Spectrometer Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Basara, Laurent; Choutko, Vitaly; Li, Qiang

    2016-06-01

    The Alpha Magnetic Spectrometer (AMS) is a high energy particle detector installed and operating on board of the International Space Station (ISS) since May 2011. So far more than 70 billion cosmic ray events have been recorded by AMS. In the present paper the Electromagnetic Calorimeter (ECAL) detector of AMS is used to measure cosmic ray nuclear charge magnitudes up to Z=10. The obtained charge magnitude resolution is about 0.1 and 0.3 charge unit for Helium and Carbon, respectively. These measurements are important for an accurate determination of the interaction probabilities of various nuclei with the AMS materials. The ECAL charge calibration and measurement procedures are presented.

  11. Noninvasive nuclear magnetic resonance profiling of painting layers

    NASA Astrophysics Data System (ADS)

    Presciutti, Federica; Perlo, Juan; Casanova, Federico; Glöggler, Stefan; Miliani, Costanza; Blümich, Bernhard; Brunetti, Brunetto Giovanni; Sgamellotti, Antonio

    2008-07-01

    In this work we demonstrate the potential of single-sided nuclear magnetic resonance (NMR) sensors to access deeper layers of paintings noninvasively by means of high-resolution depth profiles spanning several millimeters. The performance of the sensor in resolving painting structures was tested on models for which excellent agreement with microscopy techniques was obtained. The depth profiling NMR technique was used in situ to investigate old master paintings. The observation of differences in NMR relaxation times of tempera binders from these paintings and from artificially aged panels raises the possibility to differentiate between original and recently restored areas.

  12. In vivo Carbon-13 Nuclear Magnetic Resonance Studies of Mammals

    NASA Astrophysics Data System (ADS)

    Alger, J. R.; Sillerud, L. O.; Behar, K. L.; Gillies, R. J.; Shulman, R. G.; Gordon, R. E.; Shaw, D.; Hanley, P. E.

    1981-11-01

    Natural abundance carbon-13 nuclear magnetic resonances (NMR) from human arm and rat tissues have been observed in vivo. These signals arise primarily from triglycerides in fatty tissue. Carbon-13 NMR was also used to follow, in a living rat, the conversion of C-1--labeled glucose, which was introduced into the stomach, to C-1--labeled liver glycogen. The carbon-13 sensitivity and resolution obtained shows that natural abundance carbon-13 NMR will be valuable in the study of disorders in fat metabolism, and that experiments with substrates labeled with carbon-13 can be used to study carbohydrate metabolism in vivo.

  13. Development of Metallic Magnetic Calorimeters for Nuclear Safeguards Applications

    SciTech Connect

    Bates, Cameron Russell

    2015-03-11

    Many nuclear safeguards applications could benefit from high-resolution gamma-ray spectroscopy achievable with metallic magnetic calorimeters. This dissertation covers the development of a system for these applications based on gamma-ray detectors developed at the University of Heidelberg. It demonstrates new calorimeters of this type, which achieved an energy resolution of 45.5 eV full-width at half-maximum at 59.54 keV, roughly ten times better than current state of the art high purity germanium detectors. This is the best energy resolution achieved with a gamma-ray metallic magnetic calorimeter at this energy to date. In addition to demonstrating a new benchmark in energy resolution, an experimental system for measuring samples with metallic magnetic calorimeters was constructed at Lawrence Livermore National Laboratory. This system achieved an energy resolution of 91.3 eV full-width at half-maximum at 59.54 keV under optimal conditions. Using this system it was possible to characterize the linearity of the response, the count-rate limitations, and the energy resolution as a function of temperature of the new calorimeter. With this characterization it was determined that it would be feasible to measure 242Pu in a mixed isotope plutonium sample. A measurement of a mixed isotope plutonium sample was performed over the course of 12 days with a single two-pixel metallic magnetic calorimeter. The relative concentration of 242Pu in comparison to other plutonium isotopes was determined by direct measurement to less than half a percent accuracy. This is comparable with the accuracy of the best-case scenario using traditional indirect methods. The ability to directly measure the relative concentration of 242Pu in a sample could enable more accurate accounting and detection of indications of undeclared activities in nuclear safeguards, a better constraint on source material in forensic samples containing plutonium, and improvements in verification in a future plutonium

  14. Development of Metallic Magnetic Calorimeters for Nuclear Safeguards Applications

    NASA Astrophysics Data System (ADS)

    Bates, Cameron Russell

    Many nuclear safeguards applications could benefit from high-resolution gamma-ray spectroscopy achievable with metallic magnetic calorimeters. This dissertation covers the development of a system for these applications based on gamma-ray detectors developed at the University of Heidelberg. It demonstrates new calorimeters of this type, which achieved an energy resolution of 45.5 eV full-width at half-maximum at 59.54 keV, roughly ten times better than current state of the art high purity germanium detectors. This is the best energy resolution achieved with a gamma-ray metallic magnetic calorimeter at this energy to date. In addition to demonstrating a new benchmark in energy resolution, an experimental system for measuring samples with metallic magnetic calorimeters was constructed at Lawrence Livermore National Laboratory. This system achieved an energy resolution of 91.3 eV full-width at half-maximum at 59.54 keV under optimal conditions. Using this system it was possible to characterize the linearity of the response, the count-rate limitations, and the energy resolution as a function of temperature of the new calorimeter. With this characterization it was determined that it would be feasible to measure 242Pu in a mixed isotope plutonium sample. A measurement of a mixed isotope plutonium sample was performed over the course of 12 days with a single two-pixel metallic magnetic calorimeter. The relative concentration of 242Pu in comparison to other plutonium isotopes was determined by direct measurement to less than half a percent accuracy. This is comparable with the accuracy of the best-case scenario using traditional indirect methods. The ability to directly measure the relative concentration of 242Pu in a sample could enable more accurate accounting and detection of indications of undeclared activities in nuclear safeguards, a better constraint on source material in forensic samples containing plutonium, and improvements in verification in a future plutonium

  15. Mechanism of dynamic nuclear polarization in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Farrar, C. T.; Hall, D. A.; Gerfen, G. J.; Inati, S. J.; Griffin, R. G.

    2001-03-01

    Solid-state NMR signal enhancements of about two orders of magnitude (100-400) have been observed in dynamic nuclear polarization (DNP) experiments performed at high magnetic field (5 T) and low temperature (10 K) using the nitroxide radical 4-amino TEMPO as the source of electron polarization. Since the breadth of the 4-amino TEMPO EPR spectrum is large compared to the nuclear Larmor frequency, it has been assumed that thermal mixing (TM) is the dominate mechanism by which polarization is transferred from electron to nuclear spins. However, theoretical explanations of TM generally assume a homogeneously broadened EPR line and, since the 4-amino TEMPO line at 5 T is inhomogeneously broadened, they do not explain the observed DNP enhancements. Accordingly, we have developed a treatment of DNP that explicitly uses electron-electron cross-relaxation to mediate electron-nuclear polarization transfer. The process proceeds via spin flip-flops between pairs of electronic spin packets whose Zeeman temperatures differ from one another. To confirm the essential features of the model we have studied the field dependence of electron-electron double resonance (ELDOR) data and DNP enhancement data. Both are well simulated using a simple model of electron cross-relaxation in the inhomogeneously broadened 4-amino TEMPO EPR line.

  16. Analysis of ringing effects due to magnetic core materials in pulsed nuclear magnetic resonance circuits

    SciTech Connect

    Prabhu Gaunkar, N. Bouda, N. R. Y.; Nlebedim, I. C.; Hadimani, R. L.; Mina, M.; Jiles, D. C.; Bulu, I.; Ganesan, K.; Song, Y. Q.

    2015-05-07

    This work presents investigations and detailed analysis of ringing in a non-resonant pulsed nuclear magnetic resonance (NMR) circuit. Ringing is a commonly observed phenomenon in high power switching circuits. The oscillations described as ringing impede measurements in pulsed NMR systems. It is therefore desirable that those oscillations decay fast. It is often assumed that one of the causes behind ringing is the role of the magnetic core used in the antenna (acting as an inductive load). We will demonstrate that an LRC subcircuit is also set-up due to the inductive load and needs to be considered due to its parasitic effects. It is observed that the parasitics associated with the inductive load become important at certain frequencies. The output response can be related to the response of an under-damped circuit and to the magnetic core material. This research work demonstrates and discusses ways of controlling ringing by considering interrelationships between different contributing factors.

  17. Characterization of Oxygen Bridged Manganese Model Complexes Using Multifrequency (17)O-Hyperfine EPR Spectroscopies and Density Functional Theory.

    PubMed

    Rapatskiy, Leonid; Ames, William M; Pérez-Navarro, Montserrat; Savitsky, Anton; Griese, Julia J; Weyhermüller, Thomas; Shafaat, Hannah S; Högbom, Martin; Neese, Frank; Pantazis, Dimitrios A; Cox, Nicholas

    2015-10-29

    Multifrequency pulsed EPR data are reported for a series of oxygen bridged (μ-oxo/μ-hydroxo) bimetallic manganese complexes where the oxygen is labeled with the magnetically active isotope (17)O (I = 5/2). Two synthetic complexes and two biological metallocofactors are examined: a planar bis-μ-oxo bridged complex and a bent, bis-μ-oxo-μ-carboxylato bridge complex; the dimanganese catalase, which catalyzes the dismutation of H2O2 to H2O and O2, and the recently identified manganese/iron cofactor of the R2lox protein, a homologue of the small subunit of the ribonuclotide reductase enzyme (class 1c). High field (W-band) hyperfine EPR spectroscopies are demonstrated to be ideal methods to characterize the (17)O magnetic interactions, allowing a magnetic fingerprint for the bridging oxygen ligand to be developed. It is shown that the μ-oxo bridge motif displays a small positive isotropic hyperfine coupling constant of about +5 to +7 MHz and an anisotropic/dipolar coupling of -9 MHz. In addition, protonation of the bridge is correlated with an increase of the hyperfine coupling constant. Broken symmetry density functional theory is evaluated as a predictive tool for estimating hyperfine coupling of bridging species. Experimental and theoretical results provide a framework for the characterization of the oxygen bridge in Mn metallocofactor systems, including the water oxidizing cofactor of photosystem II, allowing the substrate/solvent interface to be examined throughout its catalytic cycle. PMID:26225537

  18. Accelerating Nuclear Magnetic Resonance (NMR) Analysis of Soil Organic Matter with Dynamic Nuclear Polarization (DNP) Enhancement

    NASA Astrophysics Data System (ADS)

    Normand, A. E.; Smith, A. N.; Long, J. R.; Reddy, K. R.

    2014-12-01

    13C magic angle spinning (MAS) solid state Nuclear Magnetic Resonance (ssNMR) has become an essential tool for discerning the chemical composition of soil organic matter (SOM). However, the technique is limited due to the inherent insensitivity of NMR resulting in long acquisition times, especially for low carbon (C) soil. The pursuits of higher magnetic fields or concentrating C with hydrofluoric acid are limited solutions for signal improvement. Recent advances in dynamic nuclear polarization (DNP) have addressed the insensitivity of NMR. DNP utilizes the greater polarization of an unpaired electron in a given magnetic field and transfers that polarization to an NMR active nucleus of interest via microwave irradiation. Signal enhancements of up to a few orders of magnitude have been achieved for various DNP experiments. In this novel study, we conduct DNP 13C cross-polarization (CP) MAS ssNMR experiments of SOM varying in soil C content and chemical composition. DNP signal enhancements reduce the experiment run time allowing samples with low C to be analyzed in hours rather than days. We compare 13C CP MAS ssNMR of SOM with multiple magnetic field strengths, hydrofluoric acid treatment, and novel DNP approaches. We also explore DNP surface enhanced NMR Spectroscopy (SENP) to determine the surface chemistry of SOM. The presented results and future DNP MAS ssNMR advances will lead to further understanding of the nature and processes of SOM.

  19. 17O excess transfer during the NO2 + O3 → NO3 + O2 reaction

    NASA Astrophysics Data System (ADS)

    Berhanu, Tesfaye Ayalneh; Savarino, Joël; Bhattacharya, S. K.; Vicars, Willliam C.

    2012-01-01

    The ozone molecule possesses a unique and distinctive 17O excess (Δ17O), which can be transferred to some of the atmospheric molecules via oxidation. This isotopic signal can be used to trace oxidation reactions in the atmosphere. However, such an approach depends on a robust and quantitative understanding of the oxygen transfer mechanism, which is currently lacking for the gas-phase NO2 + O3 reaction, an important step in the nocturnal production of atmospheric nitrate. In the present study, the transfer of Δ17O from ozone to nitrate radical (NO3) during the gas-phase NO2 + O3 → NO3 + O2 reaction was investigated in a series of laboratory experiments. The isotopic composition (δ17O, δ18O) of the bulk ozone and the oxygen gas produced in the reaction was determined via isotope ratio mass spectrometry. The Δ17O transfer function for the NO2 + O3 reaction was determined to be: Δ17O(O3*) = (1.23 ± 0.19) × Δ17O(O3)bulk + (9.02 ± 0.99). The intramolecular oxygen isotope distribution of ozone was evaluated and results suggest that the excess enrichment resides predominantly on the terminal oxygen atoms of ozone. The results obtained in this study will be useful in the interpretation of high Δ17O values measured for atmospheric nitrate, thus leading to a better understanding of the natural cycling of atmospheric reactive nitrogen.

  20. Low-lying 1- and 2+ states in 124Sn via inelastic scattering of 17O

    NASA Astrophysics Data System (ADS)

    Pellegri, L.; Bracco, A.; Crespi, F. C. L.

    2016-05-01

    The γ decay of low-lying 1-and 2+ states up to the neutron separation energy in 124Sn populate by the inelastic scattering of 17O was measured. The Angular distributions were measured both for the γ rays and the scattered 17O ions. The results are presented.

  1. A solid-state 17O NMR, X-ray, and quantum chemical study of N-α-Fmoc-protected amino acids

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Hashizume, Daisuke; Shimizu, Tadashi; Ohki, Shinobu; Yokoyama, Shigeyuki

    2008-10-01

    We report the results of a solid-state 17O NMR and X-ray investigation of 17O-enriched N-α-fluoren-9-ylmethoxycarbonyl- L-alanine (Fmoc- L-ALA) and N-α-fluoren-9-ylmethoxycarbonyl- O- t-butyl- L-serine (Fmoc- L-SER). The present X-ray results for Fmoc- L-SER show that the compound crystallized in the monoclinic space group P2 1 with unit-cell dimensions a = 5.843, b = 11.937, c = 15.042 Å, and β = 96.19°. Analysis of 17O magic-angle spinning (MAS) spectra and stationary NMR spectra recorded at multiple magnetic fields of the present Fmoc-protected amino acids yields the magnitudes of hydroxyl and carbonyl 17O electric-field-gradient (EFG) and chemical shielding (CS) tensors with the relative orientations between the two NMR tensors. The 17O quadrupole coupling constants ( CQ) are found to be 7.05-7.60 MHz and 7.90-8.35 MHz, and the spans of the CS tensors are 218-236 ppm and 450-521 ppm, for hydroxyl and carbonyl oxygen atoms, respectively. We also carry out quantum chemical calculations using density functional theory in order to investigate the effects of hydrogen-bond angles on 17O NMR parameters. It is demonstrated that, in addition to the hydrogen bond distances, hydrogen bond angles are an important factor in determining the magnitudes of these tensor components.

  2. 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

  3. Continental scale variation in 17O-excess of meteoric waters in the United States

    NASA Astrophysics Data System (ADS)

    Li, Shuning; Levin, Naomi E.; Chesson, Lesley A.

    2015-09-01

    High-precision triple oxygen isotope analysis of waters is an emerging tool in hydrological and paleoclimate research. The existing research on 17O-excess in waters includes surveys of meteoric waters and region-specific studies of high-latitude snow and tropical storms. However, a better understanding of the variation in 17O-excess of waters across large geographic regions is needed to expand the utility of triple oxygen isotope measurements. Here we present 17O-excess data from tap waters across the continental U.S., which we used as a proxy for precipitation. The 17O-excess values of tap waters ranged from -6 to +43 per meg and averaged 17 ± 11 per meg which is lower than the average 17O-excess reported for global meteoric waters, but overlaps with reported 17O-excess values of rainfall from the tropics. We observed relatively high 17O-excess values (>25 per meg) of tap waters in the northwestern U.S. and some of the lowest 17O-excess values (<5 per meg) in the states bordering the Gulf of Mexico. The latitudinal variation of 17O-excess among tap waters likely reflects the different controls on 17O-excess in precipitation. For example, re-evaporation of precipitation and convective processes influence the isotopic composition of tap waters from the southern portions of the U.S., resulting in relatively low 17O-excess values. In contrast, these effects are reduced in tap waters from the northern portions of the U.S. where snow and cold-season rainfall are primarily responsible for the majority of annual precipitation. Exceptions to the latitudinal trend are prevalent in the central portions of the U.S., where mixing and convection are likely responsible for 17O-excess values that are lower than would be expected at their latitudes. The results of this study provide both a first look at the variation of 17O-excess in meteoric waters on a continental scale and a predictive map for 17O-excess of meteoric waters in the U.S.

  4. Nuclear Magnetic Moment of the {sup 57}Cu Ground State

    SciTech Connect

    Minamisono, K.; Mertzimekis, T.J.; Pereira, J.; Mantica, P.F.; Pinter, J.S.; Stoker, J.B.; Tomlin, B.E.; Weerasiri, R.R.; Davies, A.D.; Hass, M.; Rogers, W.F.

    2006-03-17

    The nuclear magnetic moment of the ground state of {sup 57}Cu(I{sup {pi}}=3/2{sup -},T{sub 1/2}=196.3 ms) has been measured to be vertical bar {mu}({sup 57}Cu) vertical bar =(2.00{+-}0.05){mu}{sub N} using the {beta}-NMR technique. Together with the known magnetic moment of the mirror partner {sup 57}Ni, the spin expectation value was extracted as <{sigma}{sigma}{sub z}>=-0.78{+-}0.13. This is the heaviest isospin T=1/2 mirror pair above the {sup 40}Ca region for which both ground state magnetic moments have been determined. The discrepancy between the present results and shell-model calculations in the full fp shell giving {mu}({sup 57}Cu){approx}2.4{mu}{sub N} and <{sigma}{sigma}{sub z}>{approx}0.5 implies significant shell breaking at {sup 56}Ni with the neutron number N=28.

  5. TOPICAL REVIEW: Spatial localization in nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Keevil, Stephen F.

    2006-08-01

    The ability to select a discrete region within the body for signal acquisition is a fundamental requirement of in vivo NMR spectroscopy. Ideally, it should be possible to tailor the selected volume to coincide exactly with the lesion or tissue of interest, without loss of signal from within this volume or contamination with extraneous signals. Many techniques have been developed over the past 25 years employing a combination of RF coil properties, static magnetic field gradients and pulse sequence design in an attempt to meet these goals. This review presents a comprehensive survey of these techniques, their various advantages and disadvantages, and implications for clinical applications. Particular emphasis is placed on the reliability of the techniques in terms of signal loss, contamination and the effect of nuclear relaxation and J-coupling. The survey includes techniques based on RF coil and pulse design alone, those using static magnetic field gradients, and magnetic resonance spectroscopic imaging. Although there is an emphasis on techniques currently in widespread use (PRESS, STEAM, ISIS and MRSI), the review also includes earlier techniques, in order to provide historical context, and techniques that are promising for future use in clinical and biomedical applications.

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

    SciTech Connect

    Adelnia, Fatemeh; Lascialfari, Alessandro; Mariani, Manuel; Ammannato, Luca; Caneschi, Andrea; Rovai, Donella; Winpenny, Richard; Timco, Grigore; Corti, Maurizio Borsa, Ferdinando

    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 ring 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.

  7. {sup 17}O({alpha},{gamma}){sup 21}Ne and {sup 17}O({alpha},n){sup 20}Ne for the weak s process

    SciTech Connect

    Best, A.; Goerres, J.; Beard, M.; Couder, M.; Boer, R. de; Falahat, S.; Gueray, R. T.; Kontos, A.; Kratz, K.-L.; LeBlanc, P. J.; Li, Q.; O'Brien, S.; Oezkan, N.; Pignatari, M.; Sonnabend, K.; Talwar, R.; Tan, W.; Uberseder, E.; Wiescher, M.

    2012-11-20

    The ratio of the reaction rates of the competing channels {sup 17}O({alpha}{gamma}){sup 21}Ne and {sup 17}O({alpha},n){sup 20}Ne determines the efficiency of {sup 16}O as a neutron poison in the s process in low metallicity rotating stars. It has a large impact on the element production, either producing elements to the mass range of A=90 in case of a significant poisoning effect or extending the mass range up to the region of A=150 if the {gamma} channel is of negligible strength. We present an improved study of the reaction {sup 17}O({alpha},n){sup 20}Ne, including an independent measurement of the {sup 17}O({alpha},n{sub 1}){sup 20}Ne channel. A simultaneous R-Matrix fit to both the n{sub 0} and the n{sub 1} channels has been performed. New reaction rates, including recent data on the {sup 17}O({alpha},{gamma}){sup 21}Ne reaction, have been calculated and used as input for stellar network calculations and their impact on the s process in rotating massive stars is discussed.

  8. Development of a micro nuclear magnetic resonance system

    NASA Astrophysics Data System (ADS)

    Goloshevsky, Artem

    Application of Nuclear Magnetic Resonance (NMR) to on-line/in-line control of industrial processes is currently limited by equipment costs and requirements for installation. A superconducting magnet generating strong fields is the most expensive part of a typical NMR instrument. In industrial environments, fringe magnetic fields make accommodation of NMR instruments difficult. However, a portable, low-cost and low-field magnetic resonance system can be used in virtually any environment. Development of a number of hardware components for a portable, low-cost NMR instrument is reported in this dissertation. Chapter one provides a discussion on a miniaturized Helmholtz spiral radio-frequency (RF) coil (average diameter equal to 3.5 mm) and an NMR probe built around a capillary (outer diameter = 1.59 mm and inner diameter = 1.02 mm) for flow imaging. Experiments of NMR spectroscopy, static and dynamic (flow) imaging, conducted with the use of the miniaturized coil, are described. Chapter two presents a microfabricated package of two biaxial gradient coils and a Helmholtz RF coil. Planar configuration of discrete wires was used to create magnetic field gradients. Performance of the microfabricated gradient coils while imaging water flow compared well with a commercial gradient set of much larger size. Chapter three reports on flow imaging experiments with power law fluids (aqueous solutions of sodium salt of carboxymethyl cellulose (CMC)) of different viscosities, carried out in the NMR probe with the miniaturized RF coil and capillary. Viscosities of the CMC solutions were determined based on the curve fits of the velocity profiles and simultaneous measurements of the flow rates. The curve fits were carried out according to the power law model equations. The NMR viscosity measurements compared well with measurements of the same CMC samples, performed on a conventional rotational rheometer. A portable, home-built transceiver, designed for NMR applications utilizing a

  9. Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

    SciTech Connect

    Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris; Williams, Kenneth H.

    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) 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

  10. Partial homogeneity based high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Lin, Liangjie; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2014-09-29

    In nuclear magnetic resonance (NMR) technique, it is of great necessity and importance to obtain high-resolution spectra, especially under inhomogeneous magnetic fields. In this study, a method based on partial homogeneity is proposed for retrieving high-resolution one-dimensional NMR spectra under inhomogeneous fields. Signals from series of small voxels, which characterize high resolution due to small sizes, are recorded simultaneously. Then, an inhomogeneity correction algorithm is developed based on pattern recognition to correct the influence brought by field inhomogeneity automatically, thus yielding high-resolution information. Experiments on chemical solutions and fish spawn were carried out to demonstrate the performance of the proposed method. The proposed method serves as a single radiofrequency pulse high-resolution NMR spectroscopy under inhomogeneous fields and may provide an alternative of obtaining high-resolution spectra of in vivo living systems or chemical-reaction systems, where performances of conventional techniques are usually degenerated by field inhomogeneity.

  11. Nuclear magnetic resonance of iron and copper disease states

    SciTech Connect

    Runge, V.M.; Clanton, J.A.; Smith, F.W.; Hutchison, J.; Mallard, J.; Partain, C.L.; James, A.E. Jr.

    1983-11-01

    The tissue levels of paramagnetic ions are an important factor in the determination of T/sub 1/ values as observed by nuclear magnetic resonance (NMR) imaging. The increased levels of iron present in human disease states such as hemochromatosis lead to decreased T/sub 1/ values. The mean liver T/sub 1/ of three patients with iron storage disease was determined to be 130 msec, significantly different from the value of 154 msec, the mean for 14 normal controls. Whether NMR will be able to detect the increased copper levels in liver and brain in Wilson disease remains for further clinical trials to evaluate. NMR imaging, however, does serve as a noninvasive method for the diagnosis of states of iron overload and as a technique to follow progression of disease or response to medical therapy.

  12. Proton Nuclear Magnetic Resonance Relaxation Measurements in Frog Muscle

    PubMed Central

    Finch, Edward D.; Homer, Louis D.

    1974-01-01

    Proton nuclear magnetic resonance (NMR) relaxation measurements are reported for frog muscle as a function of temperature and Larmor frequency. Each T1ρ, T2, and T1 measurement covered a time domain sufficient to identify the average relaxation time for most intracellular water. Using regression analysis the data were fit with a model where intracellular water molecules are exchanging between a large compartment in which mobility is similar to ordinary water and a small compartment in which motion is restricted. The regression results suggest that: the restricted compartment exhibits a distribution of motions skewed toward that of free water; the residence time of water molecules in the restricted compartment is approximately 1 ms; and, the activation entropy for some water molecules in the restricted compartment is negative. PMID:4547668

  13. Serum metabonomics of acute leukemia using nuclear magnetic resonance spectroscopy

    PubMed Central

    Musharraf, Syed Ghulam; Siddiqui, Amna Jabbar; Shamsi, Tahir; Choudhary, M. Iqbal; Rahman, Atta-ur

    2016-01-01

    Acute leukemia is a critical neoplasm of white blood cells. In order to differentiate between the metabolic alterations associated with two subtypes of acute leukemia, acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), we investigated the serum of ALL and AML patients and compared with two controls (healthy and aplastic anemia) using 1H NMR (nuclear magnetic resonance) spectroscopy. Thirty-seven putative metabolites were identified using Carr-Purcell-Meiboom-Gill (CPMG) sequence. The use of PLS-DA and OPLS-DA models gave results with 84.38% and 90.63% classification rate, respectively. The metabolites responsible for classification are mainly lipids, lactate and glucose. Compared with controls, ALL and AML patients showed serum metabonomic differences involving aberrant metabolism pathways including glycolysis, TCA cycle, lipoprotein changes, choline and fatty acid metabolisms. PMID:27480133

  14. Nuclear magnetic resonance evaluation of stroke: a preliminary report

    SciTech Connect

    Bryan, R.N.; Willcott, M.R.; Schneiders, N.J.; Ford, J.J.; Derman, H.S.

    1983-10-01

    Nine patients who had acute and subacute stroke were examined by nuclear magnetic resonance (NMR) using a 6-MHz Bruker Instruments proton scanner. A modified Carr-Purcell-Meiboom-Gill pulse sequence was used for signal detection. The resultant string of spin-echoes was Fourier transformed into projections that were subsequently back-projected to a series of spin-echo images. From these images, spin density and T/sub 2/ were calculated for each pixel. The NMR scans revealed stroke in each of the patients, while CT demonstrated only eight of the lesions. T/sub 2/ was prolonged in all of the ischemic regions and is the most sensitive NMR parameter in detecting stroke. These preliminary results suggest that NMR scanning of patients who have acute stroke may be cliniclly useful, and that the T/sub 2/ component of the NRM signal is most important.

  15. Nuclear magnetic resonance spectral analysis and molecular properties of berberine

    NASA Astrophysics Data System (ADS)

    Huang, Ming-Ju; Lee, Ken S.; Hurley, Sharon J.

    An extensive theoretical study of berberine has been performed at the ab initio HF/6-31G**, HF/6-311G**, and B3LYP/6-311G** levels with and without solvent effects. The optimized structures are compared with X-ray data. We found that the optimized structures with solvent effects are in slightly better agreement with X-ray data than those without solvent effects. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of berberine were calculated by using the gauge-independent atomic orbital (GIAO) (with and without solvent effects), CSGT, and IGAIM methods. The calculated chemical shifts were compared with the two-dimensional NMR experimental data. Overall, the calculated chemical shifts show very good agreement with the experimental results. The harmonic vibrational frequencies for berberine were calculated at the B3LYP/6-311G** level.

  16. Protein conformation and proton nuclear-magnetic-resonance chemical shifts.

    PubMed

    Pardi, A; Wagner, G; Wüthrich, K

    1983-12-15

    The nuclear magnetic resonance (NMR) chemical shifts of the polypeptide backbone protons in basic pancreatic trypsin inhibitor from bovine organs and the inhibitors E and K from the venom of Dendroaspis polylepis polylepis have been analyzed. Using the corresponding shifts in model peptides, the chemical shifts observed in the proteins were decomposed into random-coil shifts and conformation-dependent shifts. Correlations between contributions to the latter term and the polypeptide conformation were investigated by using the crystal structure of the bovine inhibitor. In addition to the well-known ring-current effects, a correlation was found between chemical shifts of amide and C alpha protons and the length of the hydrogen bonds formed by these protons with nearby oxygen atoms as acceptor groups. There remain sizeable and as yet unexplained residual conformation shifts. Overall, the present treatment provides a satisfactory qualitative explanation for the outstandingly large shifts of backbone hydrogen atoms in these diamagnetic proteins. PMID:6198174

  17. Serum metabonomics of acute leukemia using nuclear magnetic resonance spectroscopy.

    PubMed

    Musharraf, Syed Ghulam; Siddiqui, Amna Jabbar; Shamsi, Tahir; Choudhary, M Iqbal; Rahman, Atta-Ur

    2016-01-01

    Acute leukemia is a critical neoplasm of white blood cells. In order to differentiate between the metabolic alterations associated with two subtypes of acute leukemia, acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), we investigated the serum of ALL and AML patients and compared with two controls (healthy and aplastic anemia) using (1)H NMR (nuclear magnetic resonance) spectroscopy. Thirty-seven putative metabolites were identified using Carr-Purcell-Meiboom-Gill (CPMG) sequence. The use of PLS-DA and OPLS-DA models gave results with 84.38% and 90.63% classification rate, respectively. The metabolites responsible for classification are mainly lipids, lactate and glucose. Compared with controls, ALL and AML patients showed serum metabonomic differences involving aberrant metabolism pathways including glycolysis, TCA cycle, lipoprotein changes, choline and fatty acid metabolisms. PMID:27480133

  18. Applications of nuclear magnetic resonance imaging in process engineering

    NASA Astrophysics Data System (ADS)

    Gladden, Lynn F.; Alexander, Paul

    1996-03-01

    During the past decade, the application of nuclear magnetic resonance (NMR) imaging techniques to problems of relevance to the process industries has been identified. The particular strengths of NMR techniques are their ability to distinguish between different chemical species and to yield information simultaneously on the structure, concentration distribution and flow processes occurring within a given process unit. In this paper, examples of specific applications in the areas of materials and food processing, transport in reactors and two-phase flow are discussed. One specific study, that of the internal structure of a packed column, is considered in detail. This example is reported to illustrate the extent of new, quantitative information of generic importance to many processing operations that can be obtained using NMR imaging in combination with image analysis.

  19. Spatial (data and model) and temporal variability of 17O-excess in East Antarctica

    NASA Astrophysics Data System (ADS)

    Winkler, Renato; Landais, Amaelle; Umuera, Ryu; Xiao, Cunde; Hoffmann, Georg; Jouzel, Jean; Kelley, Maxwell; Fukui, Kotaro

    2010-05-01

    For many decades stable water isotopes (δD and δ18O) are used as tracers in earth's hydrological cycle in order to get information about climatic parameters such as temperature and precipitation. In particular, δD and δ18O in ice cores permit to reconstruct the polar temperature of the past. Improvements of the analytical devices made it possible to measure also the δ17O of water with high precision. The combination of δ18O and δ17O leads to the definition of the so called 17O-excess (ln(δ17O/1000 +1)-0.528ln(δ18O/1000+1)) by analogy with the d-excess (δD -8δ18O). It has been suggested that 17O-excess in the ice cores is a more direct indicator of relative humidity of the source region than d-excess and that the combination of the two parameters is essential to reconstruct the past climatic conditions in the evaporative regions. Here we show new results for the spatial and temporal distribution of 17O-excess in East Antarctica. We especially explore the isotopic composition of the surface snow in remote regions of East Antarctica characterized by very low δ18O (between -60 and -55 permil). Then, we present the record of 17O-excess over the last deglaciation (26 to 8 kyrs BP) in the EPICA Dome C ice core. Interestingly, this 17O-excess record shows a more stable behavior than the one at Vostok. Finally, we compare our results with the spatial variability of 17O-excess in precipitation obtained by the old version of the GISS GCM model.

  20. δ17O and Δ47—The Heavens can Wait.

    NASA Astrophysics Data System (ADS)

    Olack, G.; Colman, A. S.

    2015-12-01

    Most terrestrial systems fall on or close to the Global Meteoric Water Line, GMWL, for 17O and 18O isotopes. Luz and Barken (2010) recently discussed variations from the GMWL, and typically the differences were in the 50 per meg, or 0.05‰, 17O excess. Landais et al. also looked at water from a Vostok ice core, covering the past 150,000 years, and see differences from GMWL on the order of 45 per meg 17O excess. Carbonate samples are analyze for their 13C and 18O to help understand paleo-climate, water sources, and by looking at clumped isotopes, Δ47, the excess of 13C-18O bonds measured by mass spectroscopy on m/z 47. Those samples will also carry thru the 17O-excess in their waters of formation. We modeled the effect of 17O excess on Δ47 and basically there is little effect in the 50 per meg 17O excess range. We also looked at what would happen with 18O spiked samples, presuming the spike does not add 17O. In that case, a 100 ‰ shift in 18O would give rise to -49‰ 17O excess anomaly. That shows a significant effect, a 1.8 ‰ shift in Δ47 and even a 3.5 ‰ shift in the δ13C reading. So spiked samples are not good candidates for clumped isotope analysis, terrestrial samples probably will not have enough of a 17O excess to affect Δ47 measurements, and extra-terrestrial samples will have to be checked.

  1. The 17O Excess of Stratospheric Nitrous Oxide in Mid-latitude Air

    NASA Astrophysics Data System (ADS)

    Ridley, A.; Kaiser, J.; Laube, J. C.

    2015-12-01

    Tropospheric nitrous oxide (N2O) has a 17O excess of (0.9±0.1) ‰ relative to Vienna Standard Mean Ocean Water (VSMOW). The origin of this 17O excess is under debate: tropospheric and stratospheric in-situ sources as well as isotope fractionation and isotope exchange during biological N2O production are all considered to make a contribution, as might the stratospheric photolysis sink. To constrain the relative contributions of the different processes and to improve our understanding of the underlying atmospheric chemical and microbial processes, more measurements are required. We have measured the 17O excess of stratospheric samples from mid-latitudes, from altitudes between 8 and 26 km. N2O was extracted cryogenically, separated from CO2 and CHF3 by a PoraPlotQ pre-column and then thermally decomposed in a gold furnace at 900 ºC. The precision for the 17O excess of a single 5 nmol N2O aliquot was ±0.3 ‰. This dataset significantly enhances the limited range of oxygen triple isotope measurements in mostly lower stratospheric samples reported by Cliff et al. (1999). The average 17O excess of the stratospheric samples analysed was (-0.19 ±0.46) ‰ relative to tropospheric N2O. Since the 17O excess of the first measurements of stratospheric air is not significantly different to that in tropospheric air, this data suggests that the 17O excess is not of stratospheric origin. This confirms the idea that the origin of the 17O excess is not due to either stratospheric photolysis or reaction with electronically excited oxygen atoms. It suggests that the origin of the 17O excess may therefore be related to tropospheric in situ sources, e.g. NH2+NO2 as proposed by Röckmann et al., 2001, or to microbial nitrogen conversion reactions as suggested by Kaiser and Röckmann, 2005.

  2. Observation of the Nuclear Magnetic Octupole Moment of 137Ba+

    NASA Astrophysics Data System (ADS)

    Hoffman, Matthew

    Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.

  3. Optically Pumped Nuclear Magnetic Resonance in the Quantum Hall Regimes

    NASA Astrophysics Data System (ADS)

    Barrett, S. E.; Khandelwal, P.; Kuzma, N. N.; Pfeiffer, L. N.; West, K. W.

    1997-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) Using this technique, measurements of the Knight shift (K_S)footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation time (T_1)footnote R. Tycko et al., Science 268, 1460 (1995) have been carried out in the Quantum Hall regimes. This talk will focus on our latest measurements of KS and T1 near Landau level filling ν=1, which extend our earlier results to higher magnetic fields (B=12 Tesla) and lower temperatures (T < 1 Kelvin). We will compare these results to the theoretical predictionsfootnote S. L. Sondhi et al., Phys. Rev. B 47, 16419 (1993); H. A. Fertig et al., Phys. Rev. B 50, 11018 (1994) that the charged excitations of the ν = 1 ground state are novel spin textures called skyrmions. The current status of this picture will be discussed.

  4. Multitude of 2+ discrete states in 124Sn observed via the (17O 17O'γ) reaction: Evidence for pygmy quadrupole states

    NASA Astrophysics Data System (ADS)

    Pellegri, L.; Bracco, A.; Tsoneva, N.; Avigo, R.; Benzoni, G.; Blasi, N.; Bottoni, S.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Lenske, H.; Million, B.; Morales, A. I.; Nicolini, R.; Wieland, O.; Bazzacco, D.; Bednarczyk, P.; Birkenbach, B.; Ciemała, M.; de Angelis, G.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Isocrate, R.; Kmiecik, M.; Krzysiek, M.; Lunardi, S.; Maj, A.; Mazurek, K.; Mengoni, D.; Michelagnoli, C.; Napoli, D. R.; Recchia, F.; Siebeck, B.; Siem, S.; Ur, C.; Valiente-Dobón, J. J.

    2015-07-01

    A multitude of discrete 2+ states in 124Sn with energy up to 5 MeV were populated and identified with the (17O, 17O'γ) reaction at 340 MeV. Cross sections were compared with distorted wave Born approximation predictions and in general a good agreement was found. The measured energy and intensity distributions of the 2+ states are very similar to the predictions based on self-consistent density functional theory and extended QRPA approach accounting for multiphonon degrees of freedom. This provides evidence of the excitation of the pygmy quadrupole resonance in skin nuclei.

  5. NMR study of a 17O enriched LaMnO3 stoichiometric crystal

    NASA Astrophysics Data System (ADS)

    Pinsard-Gaudart, L.; Trokiner, A.; Verkhovskii, S.; Gerashenko, A.; Dragoe, N.

    2011-12-01

    We present the synthesis and the NMR characterization of a 17O enriched LaMnO 3 crystalline sample. We checked that it is single phase and, more important, stoichiometric in oxygen. Its 17O enrichment estimated by NMR is about 5.5%. These first 17O NMR results obtained at T=415 K in an undoped parent LaMnO 3 manganite demonstrate that the two oxygen sites of the structure probe very different Mn spin correlations in the paramagnetic orbital ordered phase. This work opens the way to study experimentally the interactions responsible for the orbital order.

  6. Towards a beyond 1 GHz solid-state nuclear magnetic resonance: External lock operation in an external current mode for a 500 MHz nuclear magnetic resonance

    SciTech Connect

    Takahashi, Masato; Maeda, Hideaki; Ebisawa, Yusuke; Tennmei, Konosuke; Yanagisawa, Yoshinori; Nakagome, Hideki; Hosono, Masami; Takasugi, Kenji; Hase, Takashi; Miyazaki, Takayoshi; Fujito, Teruaki; Kiyoshi, Tsukasa; Yamazaki, Toshio

    2012-10-15

    Achieving a higher magnetic field is important for solid-state nuclear magnetic resonance (NMR). But a conventional low temperature superconducting (LTS) magnet cannot exceed 1 GHz (23.5 T) due to the critical magnetic field. Thus, we started a project to replace the Nb{sub 3}Sn innermost coil of an existing 920 MHz NMR (21.6 T) with a Bi-2223 high temperature superconducting (HTS) innermost coil. Unfortunately, the HTS magnet cannot be operated in persistent current mode; an external dc power supply is required to operate the NMR magnet, causing magnetic field fluctuations. These fluctuations can be stabilized by a field-frequency lock system based on an external NMR detection coil. We demonstrate here such a field-frequency lock system in a 500 MHz LTS NMR magnet operated in an external current mode. The system uses a {sup 7}Li sample in a microcoil as external NMR detection system. The required field compensation is calculated from the frequency of the FID as measured with a frequency counter. The system detects the FID signal, determining the FID frequency, and calculates the required compensation coil current to stabilize the sample magnetic field. The magnetic field was stabilized at 0.05 ppm/3 h for magnetic field fluctuations of around 10 ppm. This method is especially effective for a magnet with large magnetic field fluctuations. The magnetic field of the compensation coil is relatively inhomogeneous in these cases and the inhomogeneity of the compensation coil can be taken into account.

  7. New methodology for use in rotating field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Jachman, Rebecca Corina

    High-resolution NMR spectra of samples with anisotropic broadening are simplified to their isotropic spectra by fast rotation of the sample at the magic angle 54.7°. This dissertation concerns the development of novel Nuclear Magnetic Resonance (NMR) methodologies which would rotate the magnetic field instead of the sample, i.e. rotating field NMR. It also provides an overview of the NMR concepts, procedures, and experiments needed to understand the methodologies that will be used for rotating field NMR. A simple two-dimensional shimming method based on harmonic corrector rings provides arbitrary multiple order shimming corrections that are necessary for rotating field systems, but can be used in shimming other systems as well. Those results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to a factor of ten. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients. Additionally, initial investigations into a specialized pulse sequence for the rotating field NMR experiment, which allows for spinning at angles other than the magic angle and spinning slower than the anisotropic broadening is discussed. This will be useful for rotating field NMR because there are limits on how fast a field can be spun and difficulties of reaching the magic angle. This pulse sequence is a combination of the previously established projected magic angle spinning (p-MAS) and magic angle turning (MAT) pulse sequences. One of the goals of this project is for rotating field NMR to be used on biological systems. The p-MAS pulse sequence was successfully tested on bovine tissue samples, which suggests that it will be a viable methodology to use in rotating field NMR. A side experiment on steering magnetic particles by MRI gradients was also carried out. Initial investigations indicate some movement, but for total steering control, further experiments are

  8. Qualitative study of substituent effects on NMR (15)N and (17)O chemical shifts.

    PubMed

    Contreras, Rubén H; Llorente, Tomás; Pagola, Gabriel I; Bustamante, Manuel G; Pasqualini, Enrique E; Melo, Juan I; Tormena, Cláudio F

    2009-09-10

    A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitals that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-beta substituent effects on both (15)N and (17)O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and sigma-hyperconjugative interactions in saturated multicyclic compounds. PMID:19685922

  9. Qualitative Study of Substituent Effects on NMR 15N and 17O Chemical Shifts

    NASA Astrophysics Data System (ADS)

    Contreras, Rubén H.; Llorente, Tomás; Pagola, Gabriel I.; Bustamante, Manuel G.; Pasqualini, Enrique E.; Melo, Juan I.; Tormena, Cláudio F.

    2009-08-01

    A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitals that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-β substituent effects on both 15N and 17O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and σ-hyperconjugative interactions in saturated multicyclic compounds.

  10. The nuclear magnetic shielding as a function of internuclear separation

    NASA Astrophysics Data System (ADS)

    Jameson, Cynthia J.; de Dios, Angel C.

    1993-02-01

    Ab initio calculations of nuclear magnetic shielding surfaces for 23Na in the NaH molecule, 39Ar in ArNe, 21Ne in NeHe, and 39Ar in Ar...NaH are carried out over a wide range of internuclear separations, using a local origin method (LORG) which damps out the long-range errors due to incomplete basis sets. The R dependence of the intermolecular shielding in the attractive region of the potential in these systems and in Ar...Ar and Ar...Na+ are consistent with the long-range limiting forms associated with the shielding hyperpolarizability in conjunction with a mean square electric field approximation. The Cl and F shieldings over the range of nuclear displacements spanning the classical turning points of the ground vibrational states of ClF and F2 are found to be remarkably superposable upon scaling by the factors ṡRe. This holds as well for ClH compared with FH. The shielding of 23Na and 7Li in NaH and LiH molecules are almost superposable. These and the scaling of the intermolecular shielding in rare gas pairs indicate some general similarities of shielding surfaces. The systematic variation in the signs and magnitudes of the first derivative of X nuclear shielding at the equilibrium geometry in XHn molecules of the first and second row of the Periodic Table are shown to be consistent with a general shape for the shielding function σ(R), which we have found in rare gas pairs and for 23Na in NaH.

  11. Oxygen isotope dynamics of atmospheric nitrate over the Antarctic plateau: First combined measurements of ozone and nitrate 17O-excess (Δ17O)

    NASA Astrophysics Data System (ADS)

    Vicars, William; Savarino, Joël; Erbland, Joseph; Preunkert, Susanne; Jourdain, Bruno; Frey, Markus; Gil, Jaime; Legrand, Michel

    2013-04-01

    Variations in the isotopic composition of atmospheric nitrate (NO3-) provide novel indicators for important processes in boundary layer chemistry, often acting as source markers for reactive nitrogen (NOx = NO + NO2) and providing both qualitative and quantitative constraints on the pathways that determine its fate. Stable isotope ratios of nitrate (δ15N, δ17O, δ18O) offer direct insight into the nature and magnitude of the fluxes associated with different processes, thus providing unique information regarding phenomena that are often difficult to quantify from concentration measurements alone. The unique and distinctive 17O-excess (Δ17O = δ17O - 0.52 × δ18O ) of ozone (O3), which is transferred to NOx via oxidation reactions in the atmosphere, has been found to be a particularly useful isotopic fingerprint in studies of NOx transformations. Constraining the propagation of 17O-excess within the NOx cycle is critical in polar areas where there exists the possibility of extending atmospheric interpretations to the glacial/interglacial time scale using deep ice core records of nitrate. Here we present measurements of the comprehensive isotopic composition of atmospheric nitrate collected at Dome C, Antarctica during December 2011 to January 2012. Sampling was conducted within the framework of the OPALE (Oxidant Production over Antarctic Land and its Export) project, thus providing an opportunity to combine our isotopic observations with a wealth of meteorological and chemical data, including in-situ concentration measurements of the gas-phase precursors involved in nitrate production (NOx, O3, OH, HO2, etc.). Furthermore, nitrate isotope analysis has been combined in this study for the first time with parallel observations of the transferrable Δ17O of surface ozone, which was measured concurrently at Dome C using our recently developed analytical approach. This unique dataset has allowed for a direct comparison of observed Δ17O(NO3-) values to those that are

  12. The 17O(p,α)14N reaction measurement via the Trojan horse method and its application to 17O nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; Pizzone, R. G.; Burjan, S. V.; Cherubini, S.; Coc, A.; Gulino, M.; Hammache, F.; Hons, Z.; Irgaziev, B.; Kiss, G. G.; Kroha, V.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; de Séréville, N.; Somorjai, E.; Tumino, A.

    2014-05-01

    The role of oxygen in astrophysics is related to different problems as novae nucleosynthesis and gamma-ray astronomy. In particular, owing to the still present uncertainties on its rate, the 17O(p,α)14N is one of the most important reaction to be studied in order to get more information about the fate of oxygen in different astrophysical scenarios.

  13. 17O(p,α)14N reaction measurement at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; Pizzone, R. G.; Burjan, S. V.; Cherubini, S.; Coc, A.; Gulino, M.; Hammache, F.; Hons, Z.; Irgaziev, B.; Kiss, G. G.; Kroha, V.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; de Séréville, N.; Somorjai, E.; Tumino, A.

    2014-05-01

    The 17O(p,α)14N reaction is of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RG), asymptotic giant branch (AGB) stars, massive stars and classical novae. We report on the indirect study of the 17O(p,α)14N reaction via the Trojan Horse Method by applying the approach recently developed for extracting the resonance strength of narrow resonance in the ultra-low energy region.

  14. Improvement of the high-accuracy 17O(p ,α )14N reaction-rate measurement via the Trojan Horse method for application to 17O nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Tang, X. D.; Bucher, B.; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Lamm, L.; Ma, C.; Notani, M.; O'Brien, S.; Roberson, D.; Tan, W.; Wiescher, M.; Irgaziev, B.; Mukhamedzhanov, A.; Mrazek, J.; Kroha, V.

    2015-06-01

    The 17O(p ,α )14N and 17O(p ,γ )18F reactions are of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RGs), asymptotic giant branch (AGB) stars, massive stars, and classical novae. In particular, they govern the destruction of 17O and the formation of the short-lived radioisotope 18F, which is of special interest for γ -ray astronomy. At temperatures typical of the above-mentioned astrophysical scenario, T =0.01 -0.1 GK for RG, AGB, and massive stars and T =0.1 -0.4 GK for a classical nova explosion, the 17O(p ,α )14N reaction cross section is dominated by two resonances: one at about ERc m=65 keV above the 18F proton threshold energy, corresponding to the EX=5.673 MeV level in 18F, and another one at ERc m=183 keV (EX=5.786 MeV). We report on the indirect study of the 17O(p ,α )14N reaction via the Trojan Horse method by applying the approach recently developed for extracting the strength of narrow resonance at ultralow energies. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature. This value was used as input parameter for reaction-rate determination and its comparison with the result of the direct measurement is also discussed in the light of the electron screening effect.

  15. Novel nuclear magnetic resonance techniques for studying biological molecules

    SciTech Connect

    Laws, David D.

    2000-06-01

    Over the fifty-five year history of Nuclear Magnetic Resonance (NMR), considerable progress has been made in the development of techniques for studying the structure, function, and dynamics of biological molecules. The majority of this research has involved the development of multi-dimensional NMR experiments for studying molecules in solution, although in recent years a number of groups have begun to explore NMR methods for studying biological systems in the solid-state. Despite this new effort, a need still exists for the development of techniques that improve sensitivity, maximize information, and take advantage of all the NMR interactions available in biological molecules. In this dissertation, a variety of novel NMR techniques for studying biomolecules are discussed. A method for determining backbone ({phi}/{psi}) dihedral angles by comparing experimentally determined {sup 13}C{sub a}, chemical-shift anisotropies with theoretical calculations is presented, along with a brief description of the theory behind chemical-shift computation in proteins and peptides. The utility of the Spin-Polarization Induced Nuclear Overhauser Effect (SPINOE) to selectively enhance NMR signals in solution is examined in a variety of systems, as are methods for extracting structural information from cross-relaxation rates that can be measured in SPINOE experiments. Techniques for the production of supercritical and liquid laser-polarized xenon are discussed, as well as the prospects for using optically pumped xenon as a polarizing solvent. In addition, a detailed study of the structure of PrP 89-143 is presented. PrP 89-143 is a 54 residue fragment of the prion proteins which, upon mutation and aggregation, can induce prion diseases in transgenic mice. Whereas the structure of the wild-type PrP 89-143 is a generally unstructured mixture of {alpha}-helical and {beta}-sheet conformers in the solid state, the aggregates formed from the PrP 89-143 mutants appear to be mostly {beta}-sheet.

  16. Nuclear magnetic resonance experiments with dc SQUID amplifiers

    SciTech Connect

    Heaney, M.B. . Dept. of Physics Lawrence Berkeley Lab., CA )

    1990-11-01

    The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

  17. /sup 13/C nuclear magnetic resonance studies of cardiac metabolism

    SciTech Connect

    Seeholzer, S.H.

    1985-01-01

    The last decade has witnessed the increasing use of Nuclear Magnetic Resonance (NMR) techniques for following the metabolic fate of compounds specifically labeled with /sup 13/C. The goals of the present study are: (1) to develop reliable quantitative procedures for measuring the /sup 13/C enrichment of specific carbon sites in compounds enriched by the metabolism of /sup 13/C-labeled substrates in rat heart, and (2) to use these quantitative measurements of fractional /sup 13/C enrichment within the context of a mathematical flux model describing the carbon flow through the TCA cycle and ancillary pathways, as a means for obtaining unknown flux parameters. Rat hearts have been perfused in vitro with various combinations of glucose, acetate, pyruvate, and propionate to achieve steady state flux conditions, followed by perfusion with the same substrates labeled with /sup 13/C in specific carbon sites. The hearts were frozen at different times after addition of /sup 13/C-labeled substrates and neutralized perchloric acid extracts were used to obtain high resolution proton-decoupled /sup 13/C NMR spectra at 90.55 MHz. The fractional /sup 13/C enrichment (F.E.) of individual carbon sites in different metabolites was calculated from the area of the resolved resonances after correction for saturation and nuclear Overhauser effects. These F.E. measurements by /sup 13/C NMR were validated by the analysis of /sup 13/C-/sup 1/H scalar coupling patterns observed in /sup 1/H NMR spectra of the extracted metabolites. The results obtained from perfusion of hearts glucose plus either (2-/sup 13/C) acetate or (3-/sup 13/C) pyruvate are similar to those obtained by previous investigators using /sup 14/C-labeled substrates.

  18. Application of the Trojan Horse Method to study neutron induced reactions: the 17O(n, α)14C reaction

    NASA Astrophysics Data System (ADS)

    Gulino, M.; Spitaleri, C.; Tang, X. D.; Guardo, G. L.; Lamia, L.; Cherubini, S.; Bucher, B.; Burjan, V.; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Goldberg, V. Z.; Hons, Z.; Kroha, V.; Lamm, L.; La Cognata, M.; Li, C.; Ma, C.; Mrazek, J.; Mukhamedzhanov, A. M.; Notani, M.; O'Brien, S.; Pizzone, R. G.; Rapisarda, G. G.; Roberson, D.; Sergi, M. L.; Tan, W.; Thompson, I. J.; Wiescher, M.

    2014-03-01

    The reaction 17O(n, α)14C was studied using virtual neutrons coming from the quasi-free deuteron break-up in the three body reaction 17O+d → α+14C+p. This technique, called virtual neutron method, extends the Trojan Horse method to neutron-induced reactions allowing to study the reaction cross section avoiding the suppression effects coming from the penetrability of the centrifugal barrier. For incident neutron energies from thermal up to a few hundred keV, direct experiments have shown the population of two out of three expected excited states at energies 8213 keV and 8282 keV and the influence of the sub-threshold level at 8038 keV. In the present experiment the 18O excited state at E* = 8.125 MeV, missing in the direct measurement, is observed. The angular distributions of the populated resonances have been measured for the first time. The results unambiguously indicate the ability of the method to overcome the centrifugal barrier suppression effect and to pick out the contribution of the bare nuclear interaction.

  19. Developing hyperpolarized krypton-83 for nuclear magnetic resonance spectroscopy and magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Cleveland, Zackary I.

    This dissertation discusses the production of highly nonequilibrium nuclear spin polarization, referred to as hyperpolarization or hp, in the nuclear spin I = 9/2 noble gas isotope krypton-83 using spin exchange optical pumping (SEOP). This nonequilibrium polarization yields nuclear magnetic resonance (NMR) signals that are enhanced three or more orders of magnitude above those of thermally polarized krypton and enables experiments that would otherwise be impossible. Krypton-83 possesses a nuclear electric quadrupole moment that dominates the longitudinal (T1) relaxation due to coupling of the quadrupole moment to fluctuating electric field gradients generated by distortions to the spherical symmetry of the electronic environment. Relaxation slows polarization buildup and limits the maximum signal intensity but makes krypton-83 a sensitive probe of its environment. The gas-phase krypton-83 longitudinal relaxation rate increases linearly with total gas density due to binary collisions. Density independent relaxation, caused by the formation of krypton-krypton van der Waals molecules and surface adsorption, also contributes to the observed rate. Buffer gases suppress van der Waals molecule mediated relaxation by breaking apart the weakly bound krypton dimers. Surface relaxation is gas composition independent and therefore more difficult to suppress. However, this relaxation mechanism makes hp krypton-83 sensitive to important surface properties including surface-to-volume ratio, surface chemistry, and surface temperature. The presence of surfaces with high krypton adsorption affinities (i.e. hydrophobic surfaces) accelerates the relaxation times and can produce T1 contrast in hp krypton-83 magnetic resonance imaging (MRI). Tobacco smoke deposited on surfaces generates strong T1 contrast allowing the observation of smoke deposition with spatial resolution. Conversely, water adsorption on surfaces significantly lengths the T1 times due competitive surface adsorption

  20. Gradient coil system for nuclear magnetic resonance apparatus

    SciTech Connect

    Frese, G.; Siebold, H.

    1984-08-28

    A gradient coil system for an image-generating, nuclear magnetic resonance tomographic apparatus, particularly a zeugmatographic apparatus. The gradient coil system is arranged on a support body of rotational symmetry, illustratively a hollow cylindrical support body, having an axis which extends along the z-direction of an x, y, z coordinate system which has an origin in the center of imaging region. The gradient coil system contains two pairs of toroidal individual coils which are arranged symmetrically with respect to an x-y plane which extends through the center of the imaging region and which are arranged perpendicular to the z-axis. The direction of current flow in the individual coils of a coil pair is opposite to the direction of flow in the individual coils of the other coil pair. Moreover, further sets of coils are provided for generating field gradient Gx in the x-direction, and Gy in the y-direction. The hollow cylindrical shape of the support body on which the individual coils are arranged permit an imaging region having a substantially spherical volume with a substantially constant field gradient Gz to be achieved. Each of the coils has a predetermined linkage factor which corresponds to the product of the current flowing through the number of coil turns of the coil. Those coils which are arranged further from the plane of symmetry have a substantially larger linkage factor than the coils which are nearer to the plane of symmetry.

  1. Updated methodology for nuclear magnetic resonance characterization of shales

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.

    2013-01-01

    Unconventional petroleum resources, particularly in shales, are expected to play an increasingly important role in the world’s energy portfolio in the coming years. Nuclear magnetic resonance (NMR), particularly at low-field, provides important information in the evaluation of shale resources. Most of the low-field NMR analyses performed on shale samples rely heavily on standard T1 and T2 measurements. We present a new approach using solid echoes in the measurement of T1 and T1–T2 correlations that addresses some of the challenges encountered when making NMR measurements on shale samples compared to conventional reservoir rocks. Combining these techniques with standard T1 and T2 measurements provides a more complete assessment of the hydrogen-bearing constituents (e.g., bitumen, kerogen, clay-bound water) in shale samples. These methods are applied to immature and pyrolyzed oil shale samples to examine the solid and highly viscous organic phases present during the petroleum generation process. The solid echo measurements produce additional signal in the oil shale samples compared to the standard methodologies, indicating the presence of components undergoing homonuclear dipolar coupling. The results presented here include the first low-field NMR measurements performed on kerogen as well as detailed NMR analysis of highly viscous thermally generated bitumen present in pyrolyzed oil shale.

  2. Advances in Nuclear Magnetic Resonance for Drug Discovery

    PubMed Central

    Powers, Robert

    2010-01-01

    Background Drug discovery is a complex and unpredictable endeavor with a high failure rate. Current trends in the pharmaceutical industry have exasperated these challenges and are contributing to the dramatic decline in productivity observed over the last decade. The industrialization of science by forcing the drug discovery process to adhere to assembly-line protocols is imposing unnecessary restrictions, such as short project time-lines. Recent advances in nuclear magnetic resonance are responding to these self-imposed limitations and are providing opportunities to increase the success rate of drug discovery. Objective/Method A review of recent advancements in NMR technology that have the potential of significantly impacting and benefiting the drug discovery process will be presented. These include fast NMR data collection protocols and high-throughput protein structure determination, rapid protein-ligand co-structure determination, lead discovery using fragment-based NMR affinity screens, NMR metabolomics to monitor in vivo efficacy and toxicity for lead compounds, and the identification of new therapeutic targets through the functional annotation of proteins by FAST-NMR. Conclusion NMR is a critical component of the drug discovery process, where the versatility of the technique enables it to continually expand and evolve its role. NMR is expected to maintain this growth over the next decade with advancements in automation, speed of structure calculation, in-cell imaging techniques, and the expansion of NMR amenable targets. PMID:20333269

  3. Two-dimensional nuclear magnetic resonance of quadrupolar systems

    SciTech Connect

    Wang, Shuanhu

    1997-09-17

    This dissertation describes two-dimensional nuclear magnetic resonance theory and experiments which have been developed to study quadruples in the solid state. The technique of multiple-quantum magic-angle spinning (MQMAS) is extensively reviewed and expanded upon in this thesis. Specifically, MQMAS is first compared with another technique, dynamic-angle spinning (DAS). The similarity between the two techniques allows us to extend much of the DAS work to the MQMAS case. Application of MQMAS to a series of aluminum containing materials is then presented. The superior resolution enhancement through MQMAS is exploited to detect the five- and six-coordinated aluminum in many aluminosilicate glasses. Combining the MQMAS method with other experiments, such as HETCOR, greatly expands the possibility of the use of MQMAS to study a large range of problems and is demonstrated in Chapter 5. Finally, the technique switching-angle spinning (SAS) is applied to quadrupolar nuclei to fully characterize a quadrupolar spin system in which all of the 8 NMR parameters are accurately determined. This dissertation is meant to demonstrate that with the combination of two-dimensional NMR concepts and new advanced spinning technologies, a series of multiple-dimensional NMR techniques can be designed to allow a detailed study of quadrupolar nuclei in the solid state.

  4. Water Permeability of Chlorella Cell Membranes by Nuclear Magnetic Resonance

    PubMed Central

    Stout, Darryl G.; Steponkus, Peter L.; Bustard, Larry D.; Cotts, Robert M.

    1978-01-01

    Measurement by two nuclear magnetic resonance (NMR) techniques of the mean residence time τa of water molecules inside Chlorella vulgaris (Beijerinck) var. “viridis” (Chodot) is reported. The first is the Conlon and Outhred (1972 Biochim Biophys Acta 288: 354-361) technique in which extracellular water is doped with paramagnetic Mn2+ ions. Some complications in application of this technique are identified as being caused by the affinity of Chlorella cell walls for Mn2+ ions which shortens the NMR relaxation times of intra- and extracellular water. The second is based upon observations of effects of diffusion on the spin echo of intra- and extracellular water. Echo attenuation of intracellular water is distinguished from that of extracellular water by the extent to which diffusive motion is restricted. Intracellular water, being restricted to the cell volume, suffers less echo attenuation. From the dependence of echo amplitude upon gradient strength at several values of echo time, the mean residence time of intracellular water can be determined. From the mean residence time of intracellular water, the diffusional water permeability coefficient of the Chlorella membrane is calculated to be 2.1 ± 0.4 × 10−3 cm sec−1. PMID:16660456

  5. Nuclear magnetic resonance imaging of water content in the subsurface

    SciTech Connect

    J. Hendricks; T. Yao; A. Kearns

    1999-01-21

    Previous theoretical and experimental studies indicated that surface nuclear magnetic resonance (NMR) has the potential to provide cost-effective water content measurements in the subsurface and is a technology ripe for exploitation in practice. The objectives of this investigation are (a) to test the technique under a wide range of hydrogeological conditions and (b) to generalize existing NMR theories in order to correctly model NMR response from conductive ground and to assess properties of the inverse problem. Twenty-four sites with different hydrogeologic settings were selected in New Mexico and Colorado for testing. The greatest limitation of surface NMR technology appears to be the lack of understanding in which manner the NMR signal is influenced by soil-water factors such as pore size distribution, surface-to-volume ratio, paramagnetic ions dissolved in the ground water, and the presence of ferromagnetic minerals. Although the theoretical basis is found to be sound, several advances need to be made to make surface NMR a viable technology for hydrological investigations. There is a research need to investigate, under controlled laboratory conditions, how the complex factors of soil-water systems affect NMR relaxation times.

  6. Updated methodology for nuclear magnetic resonance characterization of shales.

    PubMed

    Washburn, Kathryn E; Birdwell, Justin E

    2013-08-01

    Unconventional petroleum resources, particularly in shales, are expected to play an increasingly important role in the world's energy portfolio in the coming years. Nuclear magnetic resonance (NMR), particularly at low-field, provides important information in the evaluation of shale resources. Most of the low-field NMR analyses performed on shale samples rely heavily on standard T1 and T2 measurements. We present a new approach using solid echoes in the measurement of T1 and T1-T2 correlations that addresses some of the challenges encountered when making NMR measurements on shale samples compared to conventional reservoir rocks. Combining these techniques with standard T1 and T2 measurements provides a more complete assessment of the hydrogen-bearing constituents (e.g., bitumen, kerogen, clay-bound water) in shale samples. These methods are applied to immature and pyrolyzed oil shale samples to examine the solid and highly viscous organic phases present during the petroleum generation process. The solid echo measurements produce additional signal in the oil shale samples compared to the standard methodologies, indicating the presence of components undergoing homonuclear dipolar coupling. The results presented here include the first low-field NMR measurements performed on kerogen as well as detailed NMR analysis of highly viscous thermally generated bitumen present in pyrolyzed oil shale. PMID:23719372

  7. Proton nuclear magnetic resonance studies on brain edema

    SciTech Connect

    Naruse, S.; Horikawa, Y.; Tanaka, C.; Hirakawa, K.; Nishikawa, H.; Yoshizaki, K.

    1982-06-01

    The water in normal and edematous brain tissues of rats was studied by the pulse nuclear magnetic resonance (NMR) technique, measuring the longitudinal relaxation time (T1) and the transverse relaxation time (T2). In the normal brain, T1 and T2 were single components, both shorter than in pure water. Prolongation and separation of T2 into two components, one fast and one slow, were the characteristic findings in brain edema induced by both cold injury and triethyl tin (TET), although some differences between the two types of edema existed in the content of the lesion and in the degree of changes in T1 and T2 values. Quantitative analysis of T1 and T2 values in their time course relating to water content demonstrated that prolongation of T1 referred to the volume of increased water in tissues examined, and that two phases of T2 reflected the distribution and the content of the edema fluid. From the analysis of the slow component of T2 versus water content during edema formation, it was demonstrated that the increase in edema fluid was steady, and its content was constant during formation of TET-induced edema. On the contrary, during the formation of cold-injury edema, water-rich edema fluid increased during the initial few hours, and protein-rich edema fluid increased thereafter. It was concluded that proton NMR relaxation time measurements may provide new understanding in the field of brain edema research.

  8. Spherical tensor analysis of nuclear magnetic resonance signals.

    PubMed

    van Beek, Jacco D; Carravetta, Marina; Antonioli, Gian Carlo; Levitt, Malcolm H

    2005-06-22

    In a nuclear magnetic-resonance (NMR) experiment, the spin density operator may be regarded as a superposition of irreducible spherical tensor operators. Each of these spin operators evolves during the NMR experiment and may give rise to an NMR signal at a later time. The NMR signal at the end of a pulse sequence may, therefore, be regarded as a superposition of spherical components, each derived from a different spherical tensor operator. We describe an experimental method, called spherical tensor analysis (STA), which allows the complete resolution of the NMR signal into its individual spherical components. The method is demonstrated on a powder of a (13)C-labeled amino acid, exposed to a pulse sequence generating a double-quantum effective Hamiltonian. The propagation of spin order through the space of spherical tensor operators is revealed by the STA procedure, both in static and rotating solids. Possible applications of STA to the NMR of liquids, liquid crystals, and solids are discussed. PMID:16035785

  9. 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.

  10. Monitoring iron mineralization processes using nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Keating, Kristina

    Proton nuclear magnetic resonance (NMR) measurements can be used to probe the molecular-scale physical and chemical environment of water in the pore space of geological materials. In geophysics, NMR relaxation measurements are used in to measure water content and estimate permeability in the top 100 m of Earth's surface. The goal of the research presented in this thesis is to determine if NMR can also be used in geophysical applications to monitor iron mineralization processes associated with contaminant remediation. The first part of the research presented in this thesis focuses on understanding the effect of iron mineral form and redox state on the NMR relaxation response of water in geologic material. Laboratory NMR measurements were made on Fe(III)-bearing minerals (ferrihydrite, lepidocrocite, goethite, and hematite), Fe(II)-bearing minerals (siderite, pyrite, and troilite), and a mixed valence iron-bearing mineral (magnetite). The results of these measurements show that the relaxation rate of water is strongly dependent on the mineral form of iron. Shown in the final section of this thesis are results from an experiment exploring temporal changes in the measured NMR relaxation rates during the reaction of ferrihydrite with aqueous Fe(II). These results show that NMR can be used to monitor temporal chemical changes in iron minerals. I conclude that this research shows that NMR indeed has the potential to be used as a tool for monitoring geochemical reactions associated with contaminant remediation.

  11. Nuclear magnetic resonance proton imaging of bone pathology

    SciTech Connect

    Atlan, H.; Sigal, R.; Hadar, H.; Chisin, R.; Cohen, I.; Lanir, A.; Soudry, M.; Machtey, Y.; Schreiber, R.; Benmair, J.

    1986-02-01

    Thirty-two patients with diversified pathology were examined with a supraconductive NMR imager using spin echo with different TR and TE to obtain T1 and T2 weighted images. They included 20 tumors (12 primary, eight metastasis), six osteomyelitis, three fractures, two osteonecrosis, and one diffuse metabolic (Gaucher) disease. In all cases except for the stress fractures, the bone pathology was clearly visualized in spite of the normal lack of signal from the compact cortical bone. Nuclear magnetic resonance (NMR) imaging proved to be at least as sensitive as radionuclide scintigraphy but much more accurate than all other imaging procedures including computed tomography (CT) and angiography to assess the extension of the lesions, especially in tumors extended to soft tissue. This is due both to easy acquisition of sagittal and coronal sections and to different patterns of pathologic modifications of T1 and T2 which are beginning to be defined. It is hoped that more experience in clinical use of these patterns will help to discriminate between tumor extension and soft-tissue edema. We conclude that while radionuclide scintigraphy will probably remain the most sensitive and easy to perform screening test for bone pathology, NMR imaging, among noninvasive diagnostic procedures, appears to be at least as specific as CT. In addition, where the extension of the lesions is concerned, NMR imaging is much more informative than CT. In pathology of the spine, the easy visualization of the spinal cord should decrease the need for myelography.

  12. Quantum information processing by nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Havel, T. F.; Cory, D. G.; Lloyd, S.; Boulant, N.; Fortunato, E. M.; Pravia, M. A.; Teklemariam, G.; Weinstein, Y. S.; Bhattacharyya, A.; Hou, J.

    2002-03-01

    Nuclear magnetic resonance (NMR) is a direct macroscopic manifestation of the quantum mechanics of the intrinsic angular momentum of atomic nuclei. It is best known for its extraordinary range of applications, which include molecular structure determination, medical imaging, and measurements of flow and diffusion rates. Most recently, liquid-state NMR spectroscopy has been found to provide a powerful experimental tool for the development and evaluation of the coherent control techniques needed for quantum information processing. This burgeoning new interdisciplinary field has the potential to achieve cryptographic, communications, and computational feats far beyond what is possible with known classical physics. Indeed, NMR has made the demonstration of many of these feats sufficiently simple to be carried out by high school summer interns working in our laboratory (see the last two authors). In this paper the basic principles of quantum information processing by NMR spectroscopy are described, along with several illustrative experiments suitable for incorporation into the undergraduate physics curriculum. These experiments are spin-spin interferometry, an implementation of the quantum Fourier transform, and the quantum simulation of a harmonic oscillator.

  13. Discrete decoding based ultrafast multidimensional nuclear magnetic resonance spectroscopy

    SciTech Connect

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

    2015-07-14

    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.

  14. A nuclear magnetic resonance study of water in aggrecan solutions

    PubMed Central

    Foster, Richard J.; Damion, Robin A.; Baboolal, Thomas G.; Smye, Stephen W.; Ries, Michael E.

    2016-01-01

    Aggrecan, a highly charged macromolecule found in articular cartilage, was investigated in aqueous salt solutions with proton nuclear magnetic resonance. The longitudinal and transverse relaxation rates were determined at two different field strengths, 9.4 T and 0.5 T, for a range of temperatures and aggrecan concentrations. The diffusion coefficients of the water molecules were also measured as a function of temperature and aggrecan concentration, using a pulsed field gradient technique at 9.4 T. Assuming an Arrhenius relationship, the activation energies for the various relaxation processes and the translational motion of the water molecules were determined from temperature dependencies as a function of aggrecan concentration in the range 0–5.3% w/w. The longitudinal relaxation rate and inverse diffusion coefficient were approximately equally dependent on concentration and only increased by upto 20% from that of the salt solution. The transverse relaxation rate at high field demonstrated greatest concentration dependence, changing by an order of magnitude across the concentration range examined. We attribute this primarily to chemical exchange. Activation energies appeared to be approximately independent of aggrecan concentration, except for that of the low-field transverse relaxation rate, which decreased with concentration. PMID:27069663

  15. Nuclear magnetic resonance studies of bovine γB-crystallin

    NASA Astrophysics Data System (ADS)

    Thurston, George; Mills, Jeffrey; Michel, Lea; Mathews, Kaylee; Zanet, John; Payan, Angel; van Nostrand, Keith; Kotlarchyk, Michael; Ross, David; Wahle, Christopher; Hamilton, John

    Anisotropy of shape and/or interactions play an important role in determining the properties of concentrated solutions of the eye lens protein, γB-crystallin, including its liquid-liquid phase transition. We are studying γB anisotropic interactions with use of nuclear magnetic resonance (NMR) concentration- and temperature-dependent chemical shift perturbations (CSPs). We analyze two-dimensional heteronuclear spin quantum coherence (HSQC) spectra on backbone nitrogen and attached hydrogen nuclei for CSPs, up to 3 percent volume fraction. Cumulative distribution functions of the CSPs show a concentration and temperature-dependent spread. Many peaks that are highly shifted with either concentration or temperature are close (i) crystal intermolecular contacts (ii) locations of cataractogenic point mutations of a homologous human protein, human γD-crystallin, and (iii) charged amino-acid residues. We also discuss the concentration- and temperature-dependence of NMR and quasielastic light scattering measurements of rotational and translational diffusion of γB crystallin in solution, affected by interprotein attractions. Supported by NIH EY018249.

  16. Optically Pumped Nuclear Magnetic Resonance in the Quantum Hall Regimes

    NASA Astrophysics Data System (ADS)

    Barrett, S. E.; Tycko, R.; Dabbagh, G.; Pfeiffer, L. N.; West, K. W.

    1996-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) Using this technique, measurements of the Knight shiftfootnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation timefootnote R. Tycko et al., Science 268, 1460 (1995) have been carried out in the Quantum Hall regimes. It is clear from these measurements that probing the electronic spin degree of freedom can lead to new insights about the effect of interactions on the many-body ground state and low-lying excited states of these systems. For example, the Knight shift measurements provided the first experimental support for the recent theoretical predictionsfootnote S. L. Sondhi et al., Phys. Rev. B 47, 16419 (1993); H. A. Fertig et al., Phys. Rev. B 50, 11018 (1994) that the charged excitations of the ν = 1 ground state are novel spin textures called skyrmions. The current status of this picture will be discussed.

  17. Features of influence of dc magnetic field pulses on a nuclear spin echo in magnets

    NASA Astrophysics Data System (ADS)

    Mamniashvili, G. I.; Gegechkori, T. O.; Akhalkatsi, A. M.; Gavasheli, C. A.

    2012-06-01

    Signal intensities of a two-pulse nuclear spin echo as a function of parameters of dc magnetic field pulses are measured in the series of materials: Li0.5Fe2.5-xZnxO4 (x < 0.25) (enriched in 57Fe isotope to 96.8%), NiMnSb, Co2MnSi, La1-хСахMnO3 (x = 0.2; 0.25) and polycrystalline Co. Two types of dependences of these signals on a supplying time of such pulses with respect to the times of the exciting RF pulses are found. The mechanisms of influence of a domain structure and a dynamic frequency shift on the observed features of the investigated signals are discussed.

  18. Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance

    SciTech Connect

    Mamone, Salvatore Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H.; Lei, Xuegong; Li, Yongjun; Goh, Kelvin; Horsewill, Anthony J.

    2014-05-21

    The water-endofullerene H{sub 2}O@C{sub 60} provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H{sub 2}O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H{sub 2}O molecules is catalysed by {sup 13}C nuclei present in the cages.

  19. Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mamone, Salvatore; Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Lei, Xuegong; Li, Yongjun; Denning, Mark; Carravetta, Marina; Goh, Kelvin; Horsewill, Anthony J.; Whitby, Richard J.; Levitt, Malcolm H.

    2014-05-01

    The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by 13C nuclei present in the cages.

  20. Characterizing Oxygen Local Environments in Paramagnetic Battery Materials via (17)O NMR and DFT Calculations.

    PubMed

    Seymour, Ieuan D; Middlemiss, Derek S; Halat, David M; Trease, Nicole M; Pell, Andrew J; Grey, Clare P

    2016-08-01

    Experimental techniques that probe the local environment around O in paramagnetic Li-ion cathode materials are essential in order to understand the complex phase transformations and O redox processes that can occur during electrochemical delithiation. While Li NMR is a well-established technique for studying the local environment of Li ions in paramagnetic battery materials, the use of (17)O NMR in the same materials has not yet been reported. In this work, we present a combined (17)O NMR and hybrid density functional theory study of the local O environments in Li2MnO3, a model compound for layered Li-ion batteries. After a simple (17)O enrichment procedure, we observed five resonances with large (17)O shifts ascribed to the Fermi contact interaction with directly bonded Mn(4+) ions. The five peaks were separated into two groups with shifts at 1600 to 1950 ppm and 2100 to 2450 ppm, which, with the aid of first-principles calculations, were assigned to the (17)O shifts of environments similar to the 4i and 8j sites in pristine Li2MnO3, respectively. The multiple O environments in each region were ascribed to the presence of stacking faults within the Li2MnO3 structure. From the ratio of the intensities of the different (17)O environments, the percentage of stacking faults was found to be ca. 10%. The methodology for studying (17)O shifts in paramagnetic solids described in this work will be useful for studying the local environments of O in a range of technologically interesting transition metal oxides. PMID:27404908

  1. Scaling of transverse nuclear magnetic relaxation due to magnetic nanoparticle aggregation.

    PubMed

    Brown, Keith A; Vassiliou, Christophoros C; Issadore, David; Berezovsky, Jesse; Cima, Michael J; Westervelt, R M

    2010-10-01

    The aggregation of superparamagnetic iron oxide (SPIO) nanoparticles decreases the transverse nuclear magnetic resonance (NMR) relaxation time T2CP of adjacent water molecules measured by a Carr-Purcell-Meiboom-Gill (CPMG) pulse-echo sequence. This effect is commonly used to measure the concentrations of a variety of small molecules. We perform extensive Monte Carlo simulations of water diffusing around SPIO nanoparticle aggregates to determine the relationship between T2CP and details of the aggregate. We find that in the motional averaging regime T2CP scales as a power law with the number N of nanoparticles in an aggregate. The specific scaling is dependent on the fractal dimension d of the aggregates. We find T2CP∝N-0.44 for aggregates with d = 2.2, a value typical of diffusion limited aggregation. We also find that in two-nanoparticle systems, T2CP is strongly dependent on the orientation of the two nanoparticles relative to the external magnetic field, which implies that it may be possible to sense the orientation of a two-nanoparticle aggregate. To optimize the sensitivity of SPIO nanoparticle sensors, we propose that it is best to have aggregates with few nanoparticles, close together, measured with long pulse-echo times. PMID:20689678

  2. Non-invasive measurement of cerebral oxygen metabolism in the mouse brain by ultra-high field (17)O MR spectroscopy.

    PubMed

    Cui, Weina; Zhu, Xiao-Hong; Vollmers, Manda L; Colonna, Emily T; Adriany, Gregor; Tramm, Brandon; Dubinsky, Janet M; Öz, Gülin

    2013-12-01

    To assess cerebral energetics in transgenic mouse models of neurologic disease, a robust, efficient, and practical method for quantification of cerebral oxygen consumption is needed. (17)O magnetic resonance spectroscopy (MRS) has been validated to measure cerebral metabolic rate of oxygen (CMRO2) in the rat brain; however, mice present unique challenges because of their small size. We show that CMRO2 measurements with (17)O MRS in the mouse brain are highly reproducible using 16.4 Tesla and a newly designed oxygen delivery system. The method can be utilized to measure mitochondrial function in mice quickly and repeatedly, without oral intubation, and has numerous potential applications to study cerebral energetics. PMID:24064490

  3. Non-invasive measurement of cerebral oxygen metabolism in the mouse brain by ultra-high field 17O MR spectroscopy

    PubMed Central

    Cui, Weina; Zhu, Xiao-Hong; Vollmers, Manda L; Colonna, Emily T; Adriany, Gregor; Tramm, Brandon; Dubinsky, Janet M; Öz, Gülin

    2013-01-01

    To assess cerebral energetics in transgenic mouse models of neurologic disease, a robust, efficient, and practical method for quantification of cerebral oxygen consumption is needed. 17O magnetic resonance spectroscopy (MRS) has been validated to measure cerebral metabolic rate of oxygen (CMRO2) in the rat brain; however, mice present unique challenges because of their small size. We show that CMRO2 measurements with 17O MRS in the mouse brain are highly reproducible using 16.4 Tesla and a newly designed oxygen delivery system. The method can be utilized to measure mitochondrial function in mice quickly and repeatedly, without oral intubation, and has numerous potential applications to study cerebral energetics. PMID:24064490

  4. The thermonuclear reaction rate of 17O(p, γ)18F--a low-energy, high beam current study at LENA

    NASA Astrophysics Data System (ADS)

    Buckner, Matthew; Iliadis, Christian; Kelly, Keegan; Downen, Lori; Champagne, Arthur; Cesaratto, John; Longland, Richard

    2014-03-01

    Classical novae are thought to be the dominant source of 17O in our Galaxy. These energetic events produce 18F that, as it decays to 18O, drives the ejection of nuclear ``ash'' into the interstellar medium. The importance of the non-resonant component of the 17O(p, γ)18F reaction is well established, and numerous studies have been performed to analyze this reaction. However, the temperature regime relevant to explosive hydrogen burning during classical novae corresponds to very low proton bombarding energies. At these low energies, the Coulomb barrier suppresses the reaction yield in the laboratory, and environmental backgrounds dominate the detected signal making it difficult to differentiate the direct capture γ-cascade from background. At the Laboratory for Experimental Nuclear Astrophysics (LENA), our electron cyclotron resonance (ECR) ion source produces intense, low-energy protons (~ 2.0 mA at the target), and these high currents boost the thermonuclear reaction yield. The LENA facility also has a coincidence detector setup that reduces environmental background contributions. Improved 17O(p, γ)18F direct capture reaction rates are currently being determined, and our progress will be reported. The DOE NNSA Stewardship Science Graduate Fellowship under Grant no. DE-FC52-08NA28752.

  5. Nuclear magnetic resonance data of C8H10N4O2

    NASA Astrophysics Data System (ADS)

    Jain, M.

    This document is part of Subvolume C `Chemical Shifts and Coupling Constants for Hydrogen-1, Heterocycles' of Landolt-Börnstein III/40 `Nuclear Magnetic Resonance Data', Group III `Condensed Matter'.

  6. Nuclear magnetic resonance data of C16H25AsS3

    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'.

  7. Nuclear magnetic resonance data of C15H23AsS2

    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'.

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

    SciTech Connect

    Goodson, Boyd M.

    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 permit 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.

  9. 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 ...

  10. Measurments and Modeling of Δ 17O Vatiations in Atmospheric Nitrate

    NASA Astrophysics Data System (ADS)

    Michalski, G. M.; Thiemens, M. H.

    2002-12-01

    The estimated doubling of HNO3 production in the atmosphere in the next 50 years is important from both an ecological and an atmospheric chemistry perspective. The removal of NO-{3 atm} (HNO3 + aerosol nitrate) by dry and wet deposition can initiate serious environmental consequences including soil acidification, forest decline, the alteration of native plant diversity, and the promotion of eutrophication and toxic algae blooms in coastal waters. A reliable, quantitative, tracer of NO-{3 atm} deposition, particularly in regions with multiple nitrate sources and heavy nitrogen cycling is still lacking. In the atmosphere, HNO3 production is the primary sink for NOx, which via direct and catalytic production of ozone regulates the oxidative capacity of the troposphere. The impact heterogeneous versus homogenous HNO3 production exert on global O3 and OH steady state concentrations has also been demonstrated in Global 3-D chemical models. Yet, the extent that anthroprogenic activities have impacted heterogeneous and homogenous production, and how these pathways varied on ancient time scales is also unknown. Nitrate aerosols were collected in La Jolla, Ca. for a one-year period and their oxygen isotopic composition were analyzed (δ 18O and δ 17O). A large Δ 17O17O = δ 17O - 0.515 δ 18O ) was observed and this isotopic signature exhibited a strong seasonal amplitude. The variability in Δ 17O is attributed to variability in HOx and O3 oxidation rates and the seasonal variation of homogeneous versus heterogeneous nitric acid formation reactions. An isotopic model coupled to a photochemical box model reproduced the observed Δ 17O with good precision. Implications for the use of Δ 17O in nitrate as an investigative tool for NOx related chemistry in both present day atmosphere and in ancient atmospheres is discussed. The magnitude of the Δ 17O signature also has implications as a tracer of atmospheric nitrogen deposition. Both the increased detection sensitivity

  11. Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

    SciTech Connect

    Yoshimi, A.; Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S.

    2009-08-04

    A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical-coupling spin maser is improved by installation of a low-noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

  12. Isotope separation of 17O by photodissociation of ozone with near-infrared laser irradiation

    NASA Astrophysics Data System (ADS)

    Hayashida, Shigeru; Kambe, Takashi; Sato, Tetsuya; Igarashi, Takehiro; Kuze, Hiroaki

    2012-04-01

    Oxygen-17 is a stable oxygen isotope useful for various diagnostics in both engineering and medical applications. Enrichment of 17O, however, has been very costly due to the lack of appropriate methods that enable efficient production of 17O on an industrial level. In this paper, we report the first 17O-selective photodissociation of ozone at a relatively high pressure, which has been achieved by irradiating a gas mixture of 10 vol% O3-90 vol% CF4 with narrowband laser. The experiment was conducted on a pilot-plant scale. A total laser power of 1.6 W was generated by external-cavity diode lasers with all the laser wavelengths fixed at the peak of an absorption line of 16O16O17O around 1 μm. The beams were introduced into a 25 -m long photoreaction cell under the sealed-off condition with a total pressure of 20 kPa. Lower cell temperature reduced the background decomposition of ozone, and at the temperature of 158 K, an 17O enrichment factor of 2.2 was attained.

  13. Isotope separation of {sup 17}O by photodissociation of ozone with near-infrared laser irradiation

    SciTech Connect

    Hayashida, Shigeru; Kambe, Takashi; Sato, Tetsuya; Igarashi, Takehiro; Kuze, Hiroaki

    2012-04-01

    Oxygen-17 is a stable oxygen isotope useful for various diagnostics in both engineering and medical applications. Enrichment of {sup 17}O, however, has been very costly due to the lack of appropriate methods that enable efficient production of {sup 17}O on an industrial level. In this paper, we report the first {sup 17}O-selective photodissociation of ozone at a relatively high pressure, which has been achieved by irradiating a gas mixture of 10 vol% O{sub 3}-90 vol% CF{sub 4} with narrowband laser. The experiment was conducted on a pilot-plant scale. A total laser power of 1.6 W was generated by external-cavity diode lasers with all the laser wavelengths fixed at the peak of an absorption line of {sup 16}O{sup 16}O{sup 17}O around 1 {mu}m. The beams were introduced into a 25 -m long photoreaction cell under the sealed-off condition with a total pressure of 20 kPa. Lower cell temperature reduced the background decomposition of ozone, and at the temperature of 158 K, an {sup 17}O enrichment factor of 2.2 was attained.

  14. Survey of {sup 17}O excited states selectively populated by five-particle transfer reactions

    SciTech Connect

    Crisp, A. M.; Roeder, B. T.; Momotyuk, O. A.; Kemper, K. W.; Weintraub, W.; Wiedeking, M.; Keeley, N.

    2008-04-15

    The highly selective reactions {sup 12}C({sup 7}Li,d){sup 17}O and {sup 12}C({sup 6}Li,p){sup 17}O have been used to populate high-lying excited states in {sup 17}O up to 16 MeV in excitation. Several of the states are newly observed, and the existence of others in a previous study of {sup 12}C({sup 6}Li,p){sup 17}O is confirmed. The observed spectra show a clear gap of about 3 MeV, indicating an energy gap between 3p-2h and 5p-4h states in {sup 17}O. Differential cross section angular distributions have been extracted from the data for both reactions and they have been compared with finite-range DWBA calculations by assuming a ''{sup 5}He'' cluster transfer. Possible spins and parities are reported for states at 11.82 MeV (7/2{sup +}), 12.00 MeV (9/2{sup +}),12.22 MeV (7/2{sup -}), and 12.42 MeV (9/2{sup +})

  15. A Multidisciplinary Approach to High Throughput Nuclear Magnetic Resonance Spectroscopy

    PubMed Central

    Pourmodheji, Hossein; Ghafar-Zadeh, Ebrahim; Magierowski, Sebastian

    2016-01-01

    Nuclear Magnetic Resonance (NMR) is a non-contact, powerful structure-elucidation technique for biochemical analysis. NMR spectroscopy is used extensively in a variety of life science applications including drug discovery. However, existing NMR technology is limited in that it cannot run a large number of experiments simultaneously in one unit. Recent advances in micro-fabrication technologies have attracted the attention of researchers to overcome these limitations and significantly accelerate the drug discovery process by developing the next generation of high-throughput NMR spectrometers using Complementary Metal Oxide Semiconductor (CMOS). In this paper, we examine this paradigm shift and explore new design strategies for the development of the next generation of high-throughput NMR spectrometers using CMOS technology. A CMOS NMR system consists of an array of high sensitivity micro-coils integrated with interfacing radio-frequency circuits on the same chip. Herein, we first discuss the key challenges and recent advances in the field of CMOS NMR technology, and then a new design strategy is put forward for the design and implementation of highly sensitive and high-throughput CMOS NMR spectrometers. We thereafter discuss the functionality and applicability of the proposed techniques by demonstrating the results. For microelectronic researchers starting to work in the field of CMOS NMR technology, this paper serves as a tutorial with comprehensive review of state-of-the-art technologies and their performance levels. Based on these levels, the CMOS NMR approach offers unique advantages for high resolution, time-sensitive and high-throughput bimolecular analysis required in a variety of life science applications including drug discovery. PMID:27294925

  16. A Multidisciplinary Approach to High Throughput Nuclear Magnetic Resonance Spectroscopy.

    PubMed

    Pourmodheji, Hossein; Ghafar-Zadeh, Ebrahim; Magierowski, Sebastian

    2016-01-01

    Nuclear Magnetic Resonance (NMR) is a non-contact, powerful structure-elucidation technique for biochemical analysis. NMR spectroscopy is used extensively in a variety of life science applications including drug discovery. However, existing NMR technology is limited in that it cannot run a large number of experiments simultaneously in one unit. Recent advances in micro-fabrication technologies have attracted the attention of researchers to overcome these limitations and significantly accelerate the drug discovery process by developing the next generation of high-throughput NMR spectrometers using Complementary Metal Oxide Semiconductor (CMOS). In this paper, we examine this paradigm shift and explore new design strategies for the development of the next generation of high-throughput NMR spectrometers using CMOS technology. A CMOS NMR system consists of an array of high sensitivity micro-coils integrated with interfacing radio-frequency circuits on the same chip. Herein, we first discuss the key challenges and recent advances in the field of CMOS NMR technology, and then a new design strategy is put forward for the design and implementation of highly sensitive and high-throughput CMOS NMR spectrometers. We thereafter discuss the functionality and applicability of the proposed techniques by demonstrating the results. For microelectronic researchers starting to work in the field of CMOS NMR technology, this paper serves as a tutorial with comprehensive review of state-of-the-art technologies and their performance levels. Based on these levels, the CMOS NMR approach offers unique advantages for high resolution, time-sensitive and high-throughput bimolecular analysis required in a variety of life science applications including drug discovery. PMID:27294925

  17. Optically Pumped Nuclear Magnetic Resonance in the Quantum Hall Regimes

    NASA Astrophysics Data System (ADS)

    Barrett, Sean E.

    1998-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) This OPNMR technique was previously used to measure the Knight shift (K_S)footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation time (T_1)footnote R. Tycko et al., Science 268, 1460 (1995) near Landau level filling ν=1, which provided the first experimental support for the theoretical predictionsfootnote S. L. Sondhi et al., Phys. Rev. B 47, 16419 (1993); H. A. Fertig et al., Phys. Rev. B 50, 11018 (1994) that the charged excitations of the ν = 1 ground state are novel spin textures called skyrmions. We have recently demonstrated that OPNMR is possible in fields up to B=12 Tesla, and temperatures down to T= 0.3 K, making it a viable new probe of the Fractional Quantum Hall Regime. In this talk we will present our latest OPNMR measurements near Landau level filling ν=1/3, which include the first direct measurement of the electron spin polarization at ν=1/3. The spin polarization drops as the filling factor is varied away from ν=1/3, indicating that the quasiparticles and quasiholes are not fully spin-polarized. We will also show how the NMR lineshape away from ν=1/3 changes dramatically at low temperatures, which is due to slowing of the electron dynamics, and a reduction in the motional narrowing of the NMR line. The current understanding of these results will be discussed.

  18. Nuclear magnetic resonance studies of macroscopic morphology and dynamics

    SciTech Connect

    Barrall, G A

    1995-09-01

    Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.

  19. Nuclear magnetic resonance imaging. (Latest citations from the US Patent database). Published Search

    SciTech Connect

    Not Available

    1993-01-01

    The bibliography contains citations of selected patents concerning imaging systems and components used in nuclear magnetic resonance (NMR) devices. Data acquisition methods and applications in fluid flow are presented. Magnet systems used in the imaging process are briefly cited. (Contains a minimum of 159 citations and includes a subject term index and title list.)

  20. The relationship between environmental abundant electromagnetic fields and packaging shape to their effects on the 17O NMR and Raman spectra of H2O-NaCl

    NASA Astrophysics Data System (ADS)

    Abdelsamie, Maher A. A.; Rahman, Russly B. Abdul; Mustafa, Shuhaimi; Hashim, Dzulkifly

    2015-07-01

    In this study, two identical groups of four containers with different packaging shapes made of polymethyl methacrylate (PMMA) were used to store H2O-NaCl solution for seven days at ambient room temperature (25 °C). Faraday shield was used to shield one group. The surrounding electromagnetic fields were measured during the storage period by using R&S®TS-EMF EMF measurement system. Samples of H2O-NaCl were collected at the end of the storage period and examined by 17Oxygene nuclear magnetic resonance spectroscopy (17O NMR) and Raman spectroscopy. Electromagnetic simulation was used to explore the relationship between the packaging shape of H2O-NaCl containers and the environmentally abundant electromagnetic fields to their effects on the cluster size of water. The study showed variations in the cluster size of water stored inside the two groups of containers. It was observed that the cluster size of water stored in the unshielded containers was lower than that of the shielded containers. The cluster size of water stored in the unshielded pyramidal container was lower than the cluster size of water stored in the unshielded rectangular, square, and cylindrical containers. The EM simulation results showed significant variations in the total specific absorption rate SAR and maximum point SAR values induced in the H2O-NaCl solution in the unshielded container models at 2400 MHz for both vertical and horizontal polarization. It can be concluded that the variations in the values of SAR induced in H2O-NaCl solution are directly related to the variations in the cluster size of the stored water.

  1. Atmosphere-surface interactions on Mars: delta 17O measurements of carbonate from ALH 84001.

    PubMed

    Farquhar, J; Thiemens, M H; Jackson, T

    1998-06-01

    Oxygen isotope measurements of carbonate from martian meteorite ALH 84001 (delta18O = 18.3 +/- 0.4 per mil, delta17O = 10.3 +/- 0.2 per mil, and Delta17O = 0.8 +/- 0.05 per mil) are fractionated with respect to those of silicate minerals. These measurements support the existence of two oxygen isotope reservoirs (the atmosphere and the silicate planet) on Mars at the time of carbonate growth. The cause of the atmospheric oxygen isotope anomaly may be exchange between CO2 and O(1D) produced by the photodecomposition of ozone. Atmospheric oxygen isotope compositions may be transferred to carbonate minerals by CO2-H2O exchange and mineral growth. A sink of 17O-depleted oxygen, as required by mass balance, may exist in the planetary regolith. PMID:9616116

  2. The ^17O(p,α)^14N reaction measured using a novel technique

    NASA Astrophysics Data System (ADS)

    Moazen, B. H.; Blackmon, J. C.; Bardayan, D. W.; Chae, K. Y.; Chipps, K.; Domizioli, C. P.; Fitzgerald, R.; Greife, U.; Hix, W. R.; Jones, K. L.; Kozub, R. L.; Lingerfelt, E. J.; Livesay, R. J.; Nesaraja, C. D.; Pain, S. D.; Roberts, L. F.; Shriner, J. F., Jr.; Smith, M. S.; Thomas, J. S.

    2007-10-01

    We developed a new approach for measuring (p,α) reactions and applied it to measure the energy and strength of the 183 keV resonance in ^17O(p,α)^ 14N that was recently reported to significantly increase the reaction rate in novae. A beam of ^17O from the Holifield Radioactive Ion Beam Facility [ORNL] tandem accelerator bombarded hydrogen gas, which filled a differentially pumped scattering chamber at pressures up to 4 Torr. Reaction products were detected in coincidence and the vertex of the reaction was determined from the relative kinematics of the two products. Nova simulations show the new ^17O(p,α)^14N reaction rate significantly decreases ^18F production in low mass ONeMg nova but affects more energetic novae less. Results and astrophysical implications will be presented as well as comments regarding my past CEU participation. ORNL is managed by UT-Battelle for the US DOE.

  3. Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer.

    PubMed

    Tayler, Michael C D; Sjolander, Tobias F; Pines, Alexander; Budker, Dmitry

    2016-09-01

    We describe new analytical capabilities for nuclear magnetic resonance (NMR) experiments in which signal detection is performed with chemical resolution (via spin-spin J couplings) in the zero to ultra-low magnetic field region, below 1μT. Using magnetic fields in the 100μT to 1mT range, we demonstrate the implementation of conventional NMR pulse sequences with spin-species selectivity. PMID:27391123

  4. Development and applications of NMR (nuclear magnetic resonance) in low fields and zero field

    SciTech Connect

    Bielecki, A.

    1987-05-01

    This dissertation is about nuclear magnetic resonance (NMR) spectroscopy in the absence of applied magnetic fields. NMR is usually done in large magnetic fields, often as large as can be practically attained. The motivation for going the opposite way, toward zero field, is that for certain types of materials, particularly powdered or polycrystalline solids, the NMR spectra in zero field are easier to interpret than those obtained in high field. 92 refs., 60 figs., 1 tab.

  5. Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer

    NASA Astrophysics Data System (ADS)

    Tayler, Michael C. D.; Sjolander, Tobias F.; Pines, Alexander; Budker, Dmitry

    2016-09-01

    We describe new analytical capabilities for nuclear magnetic resonance (NMR) experiments in which signal detection is performed with chemical resolution (via spin-spin J couplings) in the zero to ultra-low magnetic field region, below 1 μT. Using magnetic fields in the 100 μT to 1 mT range, we demonstrate the implementation of conventional NMR pulse sequences with spin-species selectivity.

  6. CRDS of 17O enriched water between 5850 and 6671 cm-1: More than 1000 energy levels of H217O and HD17O newly determined

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Leshchishina, O.; Karlovets, E. V.; Mondelain, D.; Kassi, S.; Campargue, A.

    2016-07-01

    The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 5850 and 6671 cm-1. Two series of recordings were performed with pressure values of 1.0 and 12.0 Torr. The investigated spectral region corresponds to the important 1.55 μm transparency window of the atmosphere where water absorption is very weak. The high sensitivity of the recordings (αmin ~ 5×10-11 cm-1) allows detecting lines with intensity spanning six orders of magnitude (1.4×10-30-3.6×10-24 cm/molecule at room temperature). The experimental list includes more than 10,300 lines. The assignments of water lines were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. More than 8500 lines were assigned to 9619 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). All but four transitions of the 16O and 18O isotopologues were assigned using known experimental energy levels. More than half of the assigned H217O and HD17O transitions correspond to new (or corrected) upper energy levels. About 1000 new H217O transitions associated with upper states of the second triad and of the first hexad were identified. Most of the newly assigned HD17O transitions belong to the ν1+ν3 and 2ν2+ν3 bands. The assigned transitions allowed to newly determine or correct 20 highly excited rotational levels of the vibrational ground state of this isotopologue. Overall 791 and 266 energy levels are newly determined for H217O and HD17O, respectively. A few additional levels were corrected compared to literature values. The obtained experimental results are compared to the spectroscopic parameters provided by the HITRAN database and to the empirical energy levels recommended by an IUPAC task group.

  7. 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).

  8. High resolution δ17O-δ18O as a single mineral thermometer

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Sengupta, S.; Pack, A.

    2014-12-01

    The equilibrium relationship α17O/16Oa-b = (α18O/16Oa-b)θ makes the analysis of δ17O redundant for most terrestrial applications. However the θ term varies with temperature, so that ultra-high precision δ17O data provide additional information not available from δ18O alone. If the δ18O and δ17O values of formation water covary in a known way (e.g., meteoric water, ocean water), then a unique solution for both temperature and the δ18O of the formation fluids can be obtained from the combined δ18O-δ17O mineral values. The paired δ18O-δ17O values are in essence a single mineral thermometer. Unlike clumped isotopes or combined δ18O-δD data, the δ18O and δ17O values of a mineral have identical 'diagenetic potential', and will only be altered with a high F/R ratio. We have made an empirical determination of the temperature dependence on θ = -710/T2 + 0.5305 using Pleistocene diatom data from ODP Leg 177, Site 1093 (δ18O = 39.610, δ17O = 20.536‰), which is almost identical to Pack and Herwartz (EPSL, 2014). Application to ancient cherts gives the following results: The δ18O-δ17O values of cherts vary systematically with age, from Archean to Proterozoic to Phanerozoic. The Archean cherts are incompatible with modern seawater under any temperature conditions. Instead they have equilibrated with water of δ18O= -10±3 (‰ vs SMOW) at 50 to 70°C. These data support a lighter ocean in the Archean by ~5‰. Proterozoic cherts equilibrated at 35-50°C with meteoric water of -8±3‰ and Phanerozoic cherts equilibrated with mixed meteoric water/ocean water at similar temperatures and higher δ18O values (-3±3‰). The δ18O values of lacustrine diatoms from the Valles Caldera, NM, vary by over 20‰ between glacial and interglacial times. The combined δ18O-δ17O values of interglacial diatoms give T= ~12°C, δ18Ometeoric water = -9‰. A glacial age diatom sample gives T=<10°C, δ18Ometeoric water = -20‰. These data could not be obtained from the

  9. Dynamics of Protein Kinases: Insights from Nuclear Magnetic Resonance

    PubMed Central

    Xiao, Yao; Liddle, Jennifer C.; Pardi, Arthur; Ahn, Natalie G.

    2015-01-01

    CONSPECTUS Protein kinases are ubiquitous enzymes with critical roles in cellular processes and pathology. As a result, researchers have studied their activity and regulatory mechanisms extensively. Thousands of X-ray structures give snapshots of the architectures of protein kinases in various states of activation and ligand binding. However, the extent of and manner by which protein motions and conformational dynamics underlie the function and regulation of these important enzymes is not well understood. Nuclear magnetic resonance (NMR) methods provide complementary information about protein conformation and dynamics in solution. However, until recently, the large size of these enzymes prevented researchers from using these methods with kinases. Developments in transverse relaxation-optimized spectroscopy (TROSY)-based techniques and more efficient isotope labeling strategies are now allowing researchers to carry out NMR studies on full-length protein kinases. In this Account, we describe recent insights into the role of dynamics in protein kinase regulation and catalysis that have been gained from NMR measurements of chemical shift changes and line broadening, residual dipolar couplings, and relaxation. These findings show strong associations between protein motion and events that control kinase activity. Dynamic and conformational changes occurring at ligand binding sites and other regulatory domains of these proteins propagate to conserved kinase core regions that mediate catalytic function. NMR measurements of slow time scale (microsecond to millisecond) motions also reveal that kinases carry out global exchange processes that synchronize multiple residues and allosteric interconversion between conformational states. Activating covalent modifications or ligand binding to form the Michaelis complex can induce these global processes. Inhibitors can also exploit the exchange properties of kinases by using conformational selection to form dynamically quenched

  10. Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

    NASA Astrophysics Data System (ADS)

    Nichol, John M.; Hemesath, Eric R.; Lauhon, Lincoln J.; Budakian, Raffi

    2012-02-01

    The authors report the use of a radio frequency (rf) silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1H spins in polystyrene. To couple the 1H spins to the nanowire oscillator, a magnetic resonance force detection protocol was developed that utilizes a nanoscale current-carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited an ultralow force noise near the thermal limit of the oscillator.

  11. Measurements and Modeling of (16)O(12)C(17)O Spectroscopic Parameters at 2µm

    NASA Astrophysics Data System (ADS)

    Jacquemart, D.; Sung, K.; Brown, L. R.; Coleman, M.; Mantz, A. W.; Smith, M. A. H.

    2014-06-01

    In the present study, line-intensity measurements for 16O12C17O were performed using a high-resolution Fourier transform spectrometer (Bruker IFS-125HR) together with a Herriott cell allowing a 20.956 m absorption path. For this, a 17O-enriched CO2 gas sample mixture was used. The 16O12C17O isotopologue abundance in the sample was determined to be 0.3991 by mass spectrometry. Since a collisional narrowing effect has been observed, the Rautian profile was systematically used instead of the Voigt profile. Finally, around 1000 transitions were studied between 4604 and 5126 cm-1 involving 15 bands of the 16O12C17O isotopologue. For each of the 15 bands, transition dipole moments and Herman-Wallis factors were derived, which also enabled a global comparison with theoretical calculations and predictions achieved for carbon dioxide. For the measured and calculated line positions, the accuracy is between 0.1 - 1×10-3 cm-1. For line intensities, depending on the intensity of the band, accuracies are between 2 - 3 % for 5 cold bands and 2 hot bands and between 6 - 30 % for 8 weaker hot bands. Results from this work are compared to previous works and to HITRAN 2012. Complete line lists were generated to support atmospheric remote sensing for the Earth (e.g. GOSAT, OCO-2 ...), Mars and Venus.

  12. Investigation of Oxidative Degradation in Polymers Using (17)O NMR Spectroscopy

    SciTech Connect

    Alam, Todd M.; Celina, Mathew; Assink, Roger A.; Clough, Roger L.; Gillen, Kenneth T.; Wheeler David R.

    1999-07-20

    The thermal oxidation of pentacontane (C{sub 50}H{sub 102}), and of the homopolymer polyisoprene, has been investigated using {sup 17}O NMR spectroscopy. By performing the oxidation using {sup 17}O labeled O{sub 2} gas, it is possible to easily identify degradation products, even at relatively low concentrations. It is demonstrated that details of the degradation mechanism can be obtained from analysis of the {sup 17}O NMR spectra as a function of total oxidation. Pentacontane reveals the widest variety of reaction products, and exhibits changes in the relative product distributions with increasing O{sub 2} consumption. At low levels of oxygen incorporation, peroxides are the major oxidation product, while at later stages of degradation these species are replaced by increasing concentrations of ketones, alcohols, carboxylic acids and esters. Analyzing the product distribution can help in identification of the different free-radical decomposition pathways of hydroperoxides, including recombination, proton abstraction and chain scission, as well as secondary reactions. The {sup 17}O NMR spectra of thermally oxidized polyisoprene reveal fewer degradation functionalities, but exhibit an increased complexity in the type of observed degradation species due to structural features such as unsaturation and methyl branching. Alcohols and ethers formed from hydrogen abstraction and free radical termination.

  13. Solid state nuclear magnetic resonance investigations of advanced energy materials

    NASA Astrophysics Data System (ADS)

    Bennett, George D.

    In order to better understand the physical electrochemical changes that take place in lithium ion batteries and asymmetric hybrid supercapacitors solid state nuclear magnetic resonance (NMR) spectroscopy has been useful to probe and identify changes on the atomic and molecular level. NMR is used to characterize the local environment and investigate the dynamical properties of materials used in electrochemical storage devices (ESD). NMR investigations was used to better understand the chemical composition of the solid electrolyte interphase which form on the negative and positive electrodes of lithium batteries as well as identify the breakdown products that occur in the operation of the asymmetric hybrid supercapacitors. The use of nano-structured particles in the development of new materials causes changes in the electrical, structural and other material properties. NMR was used to investigate the affects of fluorinated and non fluorinated single wall nanotubes (SWNT). In this thesis three experiments were performed using solid state NMR samples to better characterize them. The electrochemical reactions of a lithium ion battery determine its operational profile. Numerous means have been employed to enhance battery cycle life and operating temperature range. One primary means is the choice and makeup of the electrolyte. This study focuses on the characteristics of the solid electrolyte interphase (SEI) that is formed on the electrodes surface during the charge discharge cycle. The electrolyte in this study was altered with several additives in order to determine the influence of the additives on SEI formation as well as the intercalation and de-intercalation of lithium ions in the electrodes. 7Li NMR studies where used to characterize the SEI and its composition. Solid state NMR studies of the carbon enriched acetonitrile electrolyte in a nonaqueous asymmetric hybrid supercapacitor were performed. Magic angle spinning (MAS) coupled with cross polarization NMR

  14. Nuclear magnetic resonance multiwindow analysis of proton local fields and magnetization distribution in natural and deuterated mouse muscle.

    PubMed Central

    Peemoeller, H; Pintar, M M

    1979-01-01

    The proton free-induction decays, spin-spin relaxation times, local fields in the rotating frame, and spin-lattice relaxation times in the laboratory and rotating frames, in natural and fully deuterated mouse muscle, are reported. Measurements were taken above and below freezing temperature and at two time windows on the free-induction decay. A comparative analysis show that the magnetization fractions deduced from the different experiments are in good agreement. The main conclusion is that the resolution of the (heterogeneous) muscle nuclear magnetic resonance (NMR) response is improved by the multiwindow analysis. PMID:262554

  15. High-Gradient Nanomagnets on Cantilevers for Sensitive Detection of Nuclear Magnetic Resonance

    PubMed Central

    Longenecker, Jonilyn G.; Mamin, H. J.; Senko, Alexander W.; Chen, Lei; Rettner, Charles T.; Rugar, Daniel; Marohn, John A.

    2012-01-01

    Detection of magnetic resonance as a force between a magnetic tip and nuclear spins has previously been shown to enable sub-10 nm resolution 1H imaging. Maximizing the spin force in such a magnetic resonance force microscopy (MRFM) experiment demands a high field gradient. In order to study a wide range of samples, it is equally desirable to locate the magnetic tip on the force sensor. Here we report the development of attonewton-sensitivity cantilevers with high gradient cobalt nanomagnet tips. The damage layer thickness and saturation magnetization of the magnetic material were characterized by X-ray photoelectron spectroscopy and superconducting quantum interference device magnetometry. The coercive field and saturation magnetization of an individual tip were quantified in situ using frequency-shift cantilever magnetometry. Measurements of cantilever dissipation versus magnetic field and tip-sample separation were conducted. MRFM signals from protons in a polystyrene film were studied versus rf irradiation frequency and tip-sample separation, and from this data the tip field and tip-field gradient were evaluated. Magnetic tip performance was assessed by numerically modeling the frequency dependence of the magnetic resonance signal. We observed a tip-field gradient ∂Bztip∕∂z estimated to be between 4.4 and 5.4 MT m−1, which is comparable to the gradient used in recent 4 nm resolution 1H imaging experiments and larger by nearly an order of magnitude than the gradient achieved in prior magnet-on-cantilever MRFM experiments. PMID:23033869

  16. 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.

  17. 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. PMID:26847544

  18. 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.

  19. A Search for Nonstandard Neutron Spin Interactions using Dual Species Xenon Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Larsen, Michael; Mirijanian, James; Fu, Changbo; Yan, Haiyang; Smith, Erick; Snow, Mike; Walker, Thad

    2012-06-01

    NMR measurements using polarized noble gases can constrain possible exotic spin-dependent interactions involving nucleons. A differential measurement insensitive to magnetic field fluctuations can be performed using a mixture of two polarized species with different ratios of nucleon spin to magnetic moment. We used the NMR cell test station at Northrop Grumman Corporation (NGC) (developed to evaluate dual species xenon vapor cells for the Nuclear Magnetic Resonance Gyroscope) to search for NMR frequency shifts of xenon-129 and xenon-131 when a non-magnetic zirconia rod is modulated near the NMR cell. We simultaneously excited both Xe isotopes and detected free-induction-decay transients. In combination with theoretical calculations of the neutron spin contribution to the nuclear angular momentum, the measurements put a new upper bound on possible monopole-dipole interactions of the neutron for ranges around 1mm. This work is supported by the NGC Internal Research and Development (IRAD) funding, the Department of Energy, and the NSF.

  20. Practice and applications of 17-O-excess measurements of water using novel laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Dennis, K. J.; Steig, E. J.; Vasileios, G.; Schauer, A. J.; Schoenemann, S. W.; Hoffnagle, J.

    2014-12-01

    17O-excess, defined as the deviation from the Global Meteoric Water Line (GMWL) in a plot of ln(δ18O+1) vs. ln(δ17O+1), is an evolving tool for understanding the modern water cycle and reconstructing past climate regimes. Because of competing effects between equilibrium and kinetic fractionation small variations in 17O-excess can be used, for example, to (i) infer changes in temperature and sea ice across glacial-interglacial cycles in Antarctica (Schoenemann et al., 2014), (ii) study the role of rain re-evaporation during convective events thereby improving the incorporation of isotopes into GCMs (Landais et al., 2010), and (iii) assess the role of stratospheric water vapor intrusions at high altitudes or in polar regions (Winkler et al., 2013). In natural waters, variability in 17O-excess is very small (on the order of tens of per meg, where 1 per meg is 0.001‰). Until recently, only measurements made via Isotope Ratio Mass Spectrometry (IRMS) could achieve the required precision, following time-consuming front-end chemistry that converted H2O into O2 for analysis of m/z+ 32, 33 and 34. Recent improvements in laser-based spectroscopy, e.g., Cavity Ring-Down Spectroscopy (CRDS), are enabling quicker and easier measurement of 17O-excess in water (Steig et al., 2013; 2014). The Picarro L2140-i is certified with a precision of ≤ 0.015‰; however implementation of best practices can result in an achievable precision of ≤ 0.008‰, thereby demonstrating comparable performance to IRMS. We will review our recommendations for achieving high-precision measurements of 17O-excess on the Picarro L2140-i, including how to calibrate the system, the frequency of standards analysis, the number of replicate injections and vials required, and approaches to dealing with sample-to-sample memory. We will also compare the external accuracy achieved by three distinct Picarro L2140-i analyzers for multiple waters with distinct isotopic composition.

  1. Diamond-nitrogen-vacancy electronic and nuclear spin-state anticrossings under weak transverse magnetic fields

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    We report on detailed studies of electronic and nuclear spin states in the diamond-nitrogen-vacancy (NV) center under weak transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV hyperfine level anticrossing (LAC) occurring at bias fields of tens of gauss—two orders of magnitude lower than previously reported LACs at ˜500 and ˜1000 G axial magnetic fields. We then discuss how the NV ground-state Hamiltonian can be manipulated in this regime to tailor the NV's sensitivity to environmental factors and to map into the nuclear spin state.

  2. 29Si nuclear magnetic resonance study of URu2Si2 under pressure

    NASA Astrophysics Data System (ADS)

    Shirer, K. R.; Dioguardi, A. P.; Bush, B. T.; Crocker, J.; Lin, C. H.; Klavins, P.; Cooley, J. C.; Maple, M. B.; Chang, K. B.; Poeppelmeier, K. R.; Curro, N. J.

    2016-01-01

    We report 29Si nuclear magnetic resonance measurements of single crystals and aligned powders of URu2Si2 under pressure in the hidden order and paramagnetic phases. We find that the Knight shift decreases 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. This suppression persists under pressure, and the onset temperature is mildly enhanced.

  3. Nuclear magnetic resonance relaxation and diffusion in the presence of internal gradients: the effect of magnetic field strength.

    PubMed

    Mitchell, J; Chandrasekera, T C; Johns, M L; Gladden, L F; Fordham, E J

    2010-02-01

    It is known that internal magnetic field gradients in porous materials, caused by susceptibility differences at the solid-fluid interfaces, alter the observed effective Nuclear Magnetic Resonance transverse relaxation times T2,eff. The internal gradients scale with the strength of the static background magnetic field B0. Here, we acquire data at various magnitudes of B0 to observe the influence of internal gradients on T2-T2 exchange measurements; the theory discussed and observations made are applicable to any T2-T2 analysis of heterogeneous materials. At high magnetic field strengths, it is possible to observe diffusive exchange between regions of local internal gradient extrema within individual pores. Therefore, the observed exchange pathways are not associated with pore-to-pore exchange. Understanding the significance of internal gradients in transverse relaxation measurements is critical to interpreting these results. We present the example of water in porous sandstone rock and offer a guideline to determine whether an observed T2,eff relaxation time distribution reflects the pore size distribution for a given susceptibility contrast (magnetic field strength) and spin echo separation. More generally, we confirm that for porous materials T1 provides a better indication of the pore size distribution than T2,eff at high magnetic field strengths (B0>1 T), and demonstrate the data analysis necessary to validate pore size interpretations of T2,eff measurements. PMID:20365625

  4. Simulating the budget and distribution of Δ17O in CO2 with a global atmosphere-biosphere model

    NASA Astrophysics Data System (ADS)

    Peters, Wouter; Schneider, Linda; Hofmann, Magdalena E. G.; van der Velde, Ivar; Röckmann, Thomas

    2015-04-01

    The isotope ratios of 16O, 17O and 18O in CO2 are referred to as the triple-oxygen isotope composition of CO2, and have long held promise to better understand terrestrial carbon cycling. However, measurement precision as well as an incomplete understanding of fractionation during equilibrium exchange and diffusion of CO2 have been a challenge, especially for the estimation of gross primary production (GPP) and respiration from measured δ17O and δ18O isotope ratios in CO2. The excess-17O in CO2 (Δ17O), defined as the deviation of the δ17O and δ18O ratios from an expected mass-dependent fractionation line, is in principle easier to interpret as many processes that simultaneously affect δ17O and δ18O are not reflected in Δ17O. Two global box model simulations suggest that atmospheric Δ17O is therefore mostly determined by transport of relatively δ17O enriched CO2 from the stratosphere, and its equilibration in leaf-water back to an excess of close to zero, following diffusion as part of photosynthetic CO2 uptake by vegetation. This makes Δ17O an interesting tracer for photosynthesis at the global scale, and the first decadal time series have recently been published that indeed suggest strong GPP-driven variations in atmospheric Δ17O. In this study, we expand the modeling of Δ17O beyond the current two global box model results published by explicitly simulating the global atmospheric Δ17O distribution over a five year period. We specifically are interested whether regional gradients in Δ17O in areas with large GPP such as Amazonia leave an imprint on Δ17O that can be measured with the rapidly improving measurement precision (10-40 permeg currently). Therefore, we used the SIBCASA biosphere model at 1x1 degrees globally to simulate hourly fluxes of Δ17O into and out of C3 and C4 vegetation as well as soils. These fluxes were then fed into the TM5 atmospheric transport model at 6x4 degrees horizontal resolution to simulate the hourly spatial gradients in

  5. Ferromagnetic ordering in NpAl2: Magnetic susceptibility and 27Al nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Martel, L.; Griveau, J.-C.; Eloirdi, R.; Selfslag, C.; Colineau, E.; Caciuffo, R.

    2015-08-01

    We report on the magnetic properties of the neptunium based ferromagnetic compound NpAl2. We used magnetization measurements and 27Al NMR spectroscopy to access magnetic features related to the paramagnetic and ordered states (TC=56 K). While very precise DC SQUID magnetization measurements confirm ferromagnetic ordering, they show a relatively small hysteresis loop at 5 K reduced with a coercive field HCo~3000 Oe. The variable offset cumulative spectra (VOCS) acquired in the paramagnetic state show a high sensitivity of the 27Al nuclei spectral parameters (Knight shifts and line broadening) to the ferromagnetic ordering, even at room temperature.

  6. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2010-12-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxyde (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. We present results from numerical simulations carried out using the atmospheric chemistry box model (CAABA/MECCA) to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model confirms that diurnal variations in Δ17O of NOx are well predicted by the photochemical steady-state relationship during the day, but that at night a different approach must be employed (i.e. "fossilization" of the Δ17O of NOx as soon as the photolytical lifetime of NOx drops below ca. 5 min). We quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2 under the various environmental conditions analyzed, which is of particular relevance to larger-scale implementations of Δ17O where high computational costs cannot be afforded.

  7. Predicting (17)O NMR chemical shifts of polyoxometalates using density functional theory.

    PubMed

    Sharma, Rupali; Zhang, Jie; Ohlin, C André

    2016-03-21

    We have investigated the computation of (17)O NMR chemical shifts of a wide range of polyoxometalates using density functional theory. The effects of basis sets and exchange-correlation functionals are explored, and whereas pure DFT functionals generally predict the chemical shifts of terminal oxygen sites quite well, hybrid functionals are required for the prediction of accurate chemical shifts in conjunction with linear regression. By using PBE0/def2-tzvp//PBE0/cc-pvtz(H-Ar), lanl2dz(K-) we have computed the chemical shifts of 37 polyoxometalates, corresponding to 209 (17)O NMR signals. We also show that at this level of theory the protonation-induced pH dependence of the chemical shift of the triprotic hexaniobate Lindqvist anion, [HxNb6O19]((8-x)), can be reproduced, which suggests that hypotheses regarding loci of protonation can be confidently tested. PMID:26925832

  8. Pygmy dipole resonance in 124Sn populated by inelastic scattering of 17O

    NASA Astrophysics Data System (ADS)

    Pellegri, L.; Bracco, A.; Crespi, F. C. L.; Leoni, S.; Camera, F.; Lanza, E. G.; Kmiecik, M.; Maj, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Nicolini, R.; Vandone, V.; Wieland, O.; Bazzacco, D.; Bednarczyk, P.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Cederwall, B.; Charles, L.; Ciemala, M.; De Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Gernhäuser, R.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hess, H.; Isocrate, R.; Jolie, J.; Judson, D.; Jungclaus, A.; Karkour, N.; Krzysiek, M.; Litvinova, E.; Lunardi, S.; Mazurek, K.; Mengoni, D.; Michelagnoli, C.; Menegazzo, R.; Molini, P.; Napoli, D. R.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Salsac, M. D.; Siebeck, B.; Siem, S.; Simpson, J.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente Dobon, J. J.; Zieblinski, M.

    2014-11-01

    The γ decay from the high-lying states of 124Sn was measured using the inelastic scattering of 17O at 340 MeV. The emitted γ rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented ΔE- E silicon telescopes. The angular distribution was measured both for the γ rays and the scattered 17O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with (γ ,γ‧) and (α ,α‧ γ) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1- excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density.

  9. Nuclear quadrupole resonance studies of the SORC sequence and nuclear magnetic resonance studies of polymers

    SciTech Connect

    Jayakody, J.R.P.

    1993-12-31

    The behavior of induction signals during steady-state pulse irradiation in {sup 14}N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method. Also as part of the NQR work, cocaine base has been detected using conventional NQR techniques. The experimental results show that SORC detection can be of sufficient sensitivity to form the basis of narcotics screening devices for both mail and airline baggage. A new NMR technique, to obtain the correlation time of the random thermal motion of a polymer at temperatures near the glass transition has been introduced. The temperature dependence is a result of thermal motion. For slow-motion of a polymer chain near the glass transition, the CSA parameter begins to decrease. This motional narrowing can be interpreted to yield the correlation time of the thermal motion. In this work nitrocellulose isotopically highly enriched with {sup 15}N was studied at four different temperatures between 27{degrees} and 120{degrees} Celsius and the correlation times for polymer backbone motions were obtained. Naflon films containing water (D{sub 2}O and H{sub 2} {sup 17}O) and methanol (CH{sub 3}OD, CH{sub 3} {sup 17}OH), have been studied using deuteron and oxygen-17 NMR spectroscopy. Glassy behavior of the water domains at low temperature is evidenced by the specific nature of the {sup 2}H NMR lineshapes. Activation energies extracted from {sup 2}H spin-lattice relaxation data on the high temperature side of the T{sub 1} minimum exhibit a steady increase with increasing water content. In spite of a high degree of molecular mobility, angular-dependent spectra of both unstretched and stretched samples reflect considerable anisotrophy of the host polymer.

  10. Seasonal variations in 35S and Δ17O of sulfate aerosols on the Antarctic plateau

    NASA Astrophysics Data System (ADS)

    Hill-Falkenthal, Jason; Priyadarshi, Antra; Savarino, Joel; Thiemens, Mark

    2013-08-01

    The first reported seasonal Δ17O anomaly in sulfate aerosols and measurements of radioactive 35SO42- activities collected from Dome C, Antarctica, are reported. Δ17O values exhibit minima during summer (as low as 0.91‰) when tropospheric oxidation patterns are dominated by OH/H2O2 mechanisms. Significant enrichment during autumn and spring is observed (up to 2.40‰) as ozone oxidation increases in the troposphere relative to summer and both stratospheric sources and long-range transport become more significant to the total sulfate budget. An unexpected decrease in Δ17O is seen as winter progresses. This decline is concluded to potentially arise due to a reduction in vertical mixing in the troposphere or linked to variations in the long-range transport of sulfur species to Antarctica. 35SO42- activities exhibit maxima during summer (up to 1219 atoms 35S/m3) that correlate with the peak in stratospheric flux and minima during winter (as low as 146 atoms 35S/m3) when the lack of solar radiation substantially reduces photochemical activity. It is shown that 35S offers the potential to be used as an additional tracer to study stratospheric and tropospheric interactions and is used to estimate stratospheric input of sulfur (combination of SO2 and SO42-). Stratospheric sulfur input produces maxima during summer/autumn with an upper limit of 5.5 ng/m3 and minima during winter/spring with an upper limit of 1.1 ng/m3. From these results, it is concluded that the variation in Δ17O is more reliant upon shifts in tropospheric oxidation mechanisms and long-range transport than on changes in the stratospheric flux.

  11. [Identification of organic substances by means of spectral methods in forensic toxicological analysis. II. Nuclear magnetic resonance].

    PubMed

    Smysl, B

    1975-05-01

    In opening the paper, the authors present a brief outline of the fundamentals of nuclear magnetic resonance. Using selected cases from practice, they demonstrate the use of nuclear magnetic resonance for the purpose of forensic toxicologic analysis. The method is particularly suitable for identifying unknown organic compounds and for analysing mixtures of substances. PMID:1242821

  12. Solid-State 17O NMR Study of Benzoic Acid Adsorption On Metal Oxide Surfaces

    SciTech Connect

    Hagaman, Edward {Ed} W; Chen, Banghao; Jiao, Jian; Parsons, Williams

    2012-01-01

    Solid-state 17O NMR spectra of 17O-labeled benzoic and anisic acids are reported and benzoic acid is used to probe the surface of metal oxides. Complexes formed when benzoic acid is dry-mixed with mesoporous silica, and nonporous titania and alumina are characterized. Chemical reactions with silica are not observed. The nature of benzoic acid on silica is a function of the water content of the oxide. The acid disperses in the pores of the silica if the silica is in equilibrium with ambient laboratory humidity. The acid displays high mobility as evidenced by a liquid-like, Lorentzian resonance. Excess benzoic acid remains as the crystalline hydrogen-bonded dimer. Benzoic acid reacts with titania and alumina surfaces in equilibrium with laboratory air to form the corresponding titanium and aluminum benzoates. In both materials the oxygen of the 17O-labeled acid is bound to the metal, showing the reaction proceeds by bond formation between oxygen deficient metal sites and the oxygen of the carboxylic acid. 27Al MAS NMR confirms this mechanism for the reaction on alumina. Dry mixing of benzoic acid with alumina rapidly quenches pentacoordinate aluminum sites, excellent evidence that these sites are confined to the surface of the alumina particles.

  13. Metallogrid Single-Molecule Magnet: Solvent-Induced Nuclearity Transformation and Magnetic Hysteresis at 16 K.

    PubMed

    Huang, Wei; Shen, Fu-Xing; Wu, Shu-Qi; Liu, Li; Wu, Dayu; Zheng, Zhe; Xu, Jun; Zhang, Ming; Huang, Xing-Cai; Jiang, Jun; Pan, Feifei; Li, Yao; Zhu, Kun; Sato, Osamu

    2016-06-01

    Structural assembly and reversible transformation between a metallogrid Dy4 SMM (2) and its fragment Dy2 (1) were established in the different solvent media. The zero-field magnetization relaxation was slowed for dysprosium metallogrid (2) with relaxation barrier of Ueff = 61.3 K when compared to Dy2 (1). Both magnetic dilution and application of a moderate magnetic field suppress ground-state quantum tunneling of magnetization and result in an enhanced Ueff of 119.9 and 96.7 K for 2, respectively. Interestingly, the lanthanide metallogrid complex (2) exhibits magnetic hysteresis loop even up to 16 K at a given field sweep rate of 500 Oe/s. PMID:27164298

  14. Magnetic Separation for Nuclear Material Detection and Surveillance

    SciTech Connect

    Worl, L.A.; Devlin, D.; Hill, D.; Padilla, D.; Prenger, F.C.

    1998-08-01

    A high performance superconducting magnet is being developed for particle retrieval from field collected samples. Results show that maximum separation effectiveness is obtained when the matrix fiber diameter approaches the diameter of the particles to be captured. Experimentally, the authors obtained a single particle capture limit with 0.8{micro}m PuO{sub 2} particles with dodecane as a carrier fluid. The development of new matrix materials is being pursued through the controlled corrosion of stainless steel wool, or the deposition of nickel dendrites on the existing stainless steel matrix material. They have also derived a model from a continuity equation that uses empirically determined capture cross section values. This enables the prediction of high gradient magnetic separator performance for a variety of materials and applications. The model can be used to optimize the capture cross section and thus increase the capture efficiency.

  15. Iodine magnetic moments measured by on-line nuclear orientation

    NASA Astrophysics Data System (ADS)

    Stone, N. J.; Rikovska, J.; Green, V. R.; Shaw, T. L.; Krane, K. S.; Walker, P. M.; Grant, I. S.

    1987-03-01

    On-Line measurements of magnetic dipole moments of117 122I are interpreted using coupling of the odd particles to a deformed core. The results show interesting effects of g7/2, d5/2 orbital admixtures in the odd-A isotopes, which are close to spherical. The odd-odd isotopes118, 120I show clear examples of shape co-existence.

  16. Nuclear magnetic resonance linewidth and spin diffusion in {sup 29}Si isotopically controlled silicon

    SciTech Connect

    Hayashi, Hiroshi; Itoh, Kohei M.; Vlasenko, Leonid S.

    2008-10-15

    A nuclear magnetic resonance (NMR) study was performed with n-type silicon single crystals containing {sup 29}Si isotope abundance f ranges from 1.2% to 99.2%. The nuclear spin diffusion coefficient D has been determined from the linewidth of significantly enhanced {sup 29}Si NMR signals utilizing a developed dynamic nuclear polarization (DNP) method. The {sup 29}Si NMR linewidth depends linearly on f, at least when f<10%, and approaches {proportional_to}f{sup 1/2} dependence when f>50%. The estimated {sup 29}Si nuclear spin diffusion time T{sub sd} between phosphorus atoms used for DNP is more than ten times shorter than the nuclear polarization time T{sub 1}{sup p} of {sup 29}Si nuclei around phosphorus. Therefore, the regime of 'rapid spin diffusion' is realized in the DNP experiments.

  17. In vivo nuclear magnetic resonance spectroscopy of a transplanted brain tumour.

    PubMed Central

    Koeze, T. H.; Lantos, P. L.; Iles, R. A.; Gordon, R. E.

    1984-01-01

    In vivo nuclear magnetic resonance 31P spectroscopy was used to demonstrate different patterns of high energy phosphate metabolism in a group of malignant tumours of glial origin. In some of the more malignant tumours a decrease in adenylate energy charge was found. This was associated with a decline in phosphocreatine and an increase in sugar phosphate and inorganic phosphorus. PMID:6704312

  18. 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…

  19. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  1. 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.

  2. 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…

  3. SURFACE NUCLEAR MAGNETIC RESONANCE IMAGING OF WATER CONTENT DISTRIBUTION IN THE SUBSURFACE

    EPA Science Inventory

    The objective of this research is to advance the technology of nuclear magnetic resonance (NMR) for direct measurement of water content distributions in the subsurface. The proof-of-concept of this method has been demonstrated by Russian scientists at the Institute of Chemical Ki...

  4. Nuclear-spin-induced cotton-mouton effect in a strong external magnetic field.

    PubMed

    Fu, Li-Juan; Vaara, Juha

    2014-08-01

    Novel, high-sensitivity and high-resolution spectroscopic methods can provide site-specific nuclear information by exploiting nuclear magneto-optic properties. We present a first-principles electronic structure formulation of the recently proposed nuclear-spin-induced Cotton-Mouton effect in a strong external magnetic field (NSCM-B). In NSCM-B, ellipticity is induced in a linearly polarized light beam, which can be attributed to both the dependence of the symmetric dynamic polarizability on the external magnetic field and the nuclear magnetic moment, as well as the temperature-dependent partial alignment of the molecules due to the magnetic fields. Quantum-chemical calculations of NSCM-B were conducted for a series of molecular liquids. The overall order of magnitude of the induced ellipticities is predicted to be 10(-11) -10(-6) rad T(-1)  M(-1)  cm(-1) for fully spin-polarized nuclei. In particular, liquid-state heavy-atom systems should be promising for experiments in the Voigt setup. PMID:24862946

  5. 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...

  6. MINIATURE NUCLEAR MAGNETIC RESONANCE SPECTROMETER FOR IN-SITU AND IN-PROCESS ANALYSIS AND MONITORING

    EPA Science Inventory

    The objective of this research project is to develop a new analytical instrument based on the principle of nuclear magnetic resonance (NMR) for in-situ, in-field and in-process characterization and monitoring of various substances and chemical processes. The new instrument will b...

  7. 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…

  8. Structural Isomer Identification via NMR: A Nuclear Magnetic Resonance Experiment for Organic, Analytical, or Physical Chemistry.

    ERIC Educational Resources Information Center

    Szafran, Zvi

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment that examines the ability of nuclear magnetic resonance (NMR) to distinguish between structural isomers via resonance multiplicities and chemical shifts. Reasons for incorporating the experiment into organic, analytical, or physical chemistry…

  9. Manipulation of the nuclear spin ensemble in a quantum dot with chirped magnetic resonance pulses

    NASA Astrophysics Data System (ADS)

    Munsch, Mathieu; Wüst, Gunter; Kuhlmann, Andreas V.; Xue, Fei; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.; Poggio, Martino; Warburton, Richard J.

    2014-09-01

    The nuclear spins in nanostructured semiconductors play a central role in quantum applications. The nuclear spins represent a useful resource for generating local magnetic fields but nuclear spin noise represents a major source of dephasing for spin qubits. Controlling the nuclear spins enhances the resource while suppressing the noise. NMR techniques are challenging: the group III and V isotopes have large spins with widely different gyromagnetic ratios; in strained material there are large atom-dependent quadrupole shifts; and nanoscale NMR is hard to detect. We report NMR on 100,000 nuclear spins of a quantum dot using chirped radiofrequency pulses. Following polarization, we demonstrate a reversal of the nuclear spin. We can flip the nuclear spin back and forth a hundred times. We demonstrate that chirped NMR is a powerful way of determining the chemical composition, the initial nuclear spin temperatures and quadrupole frequency distributions for all the main isotopes. The key observation is a plateau in the NMR signal as a function of sweep rate: we achieve inversion at the first quantum transition for all isotopes simultaneously. These experiments represent a generic technique for manipulating nanoscale inhomogeneous nuclear spin ensembles and open the way to probe the coherence of such mesoscopic systems.

  10. Force Detected Nuclear Magnetic Resonance on ammonium sulfate and magnesium diboride

    NASA Astrophysics Data System (ADS)

    Chia, Han-Jong

    Nuclear magnetic resonance force microscopy (NMRFM) is a technique that combines aspects of scanning probe microscopy (SPM) and nuclear magnetic resonance (NMR) to obtain 3 dimensional nanoscale spatial resolution and perform spectroscopy. We describe the components of a helium-3 NM-RFM probe and studies of ammonium sulfate ((NH4)2SO4) and magnesium dibordie (MgB2). For our room temperature (NH4)2SO 4 studies we were able to perform a 1-D scan and perform nutation and spin echo experiments. In our 77 K MgB2 we demonstrate a 1-D scan of a 30 mum powder sample. In addition, we describe magnetic measurements of the possible dilute semiconductors MnxSc 1-xN and Fe0:1Sc 0:9N.

  11. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    SciTech Connect

    Mance, Deni; Baldus, Marc; Gast, Peter; Huber, Martina; Ivanov, Konstantin L.

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  12. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Mance, Deni; Gast, Peter; Huber, Martina; Baldus, Marc; Ivanov, Konstantin L.

    2015-06-01

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between "bulk" and "core" nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  13. Spinodal instabilities and the distillation effect in nuclear matter under strong magnetic fields

    SciTech Connect

    Rabhi, A.; Providencia, C.; Providencia, J. Da

    2009-01-15

    We study the effect of strong magnetic fields, of the order of 10{sup 18}-10{sup 19} G, on the instability region of nuclear matter at subsaturation densities. Relativistic nuclear models both with constant couplings and with density-dependent parameters are considered. It is shown that a strong magnetic field can have large effects on the instability regions giving rise to bands of instability and wider unstable regions. As a consequence, we predict larger transition densities at the inner edge of the crust of compact stars with strong magnetic fields. The direction of instability gives rise to a very strong distillation effect if the last Landau level is only partially filled. However, for almost completed Landau levels, an antidistillation effect may occur.

  14. Tracing the Atmospheric Source of Desert Nitrates Using Δ 17O

    NASA Astrophysics Data System (ADS)

    Michalski, G. M.; Holve, M.; Feldmeier, J.; Bao, H.; Reheis, M.; Bockheim, J. G.; Thiemens, M. H.

    2001-05-01

    Mineral, caliche, and soil nitrates are found throughout the worlds deserts, including the cold dry Wright Valley of Antarctica, the Atacama desert in Chile and the Mojave desert in the southwest United States. Several authors have suggested biologic sources of these nitrates while others have postulated atmospheric deposition. A recent study utilizing 18O indicated that 30%, and perhaps 100%, of nitrates found in the Atacama and Mojave were of atmospheric origin [1]. A more quantitative assessment of the source strength of atmospheric nitrates was impossible because of the high variability of δ 18 18O of atmospheric nitrates and uncertainties in conditions of biologic production. Mass independently fractionated (MIF) processes are defined and quantified by the equation Δ 17O = δ 17O - .52x δ 18O. MIF processes are associated with the photochemistry of trace gases in the atmosphere and have been found in O3, N2O, CO, and sulfate aerosols . A large MIF (Δ 17O ~ 28 ‰ ) in nitrate aerosols collected in polluted regions was recently reported [2]. Here we extend measurements of MIF in nitrate to the dry deposition of nitrate in less polluted areas (Mojave desert). In addition we trace the MIF signal as it accumulates in the regolith as nitrate salts and minerals and is mixed with biologically produced nitrate (nitrification). Also examined were the isotopic composition of soil nitrates from Antarctic dry valleys. Dust samples were collected as part of the NADP program and soils were collected throughout the Mojave and Death Valley regions of California. Isotope analysis was done in addition to soluble ion content (Cl, NO3, SO4). Dust samples collected by dry deposition samplers showed a large MIF > 20‰ approaching values measured in urban nitrate aerosol. Soils collected throughout the region showed large variations in Δ 17O from ~ 0 to 18 ‰ . The low Δ 17O values are nitrates dominated by biologic nitrification and higher values are nitrates derived by

  15. Nuclear magnetic resonance study of the collagen matrix in tendon

    NASA Astrophysics Data System (ADS)

    Krasnosselskaia, Lada Vadimovna

    Understanding of complex interactions of water with macromolecules is a prerequisite for quantitative musculoskeletal imaging and this dissertation presents a study on NMR characteristics of water in anisotropic environment of the collagen extracellular matrix of tendon. The first chapter of the dissertation analyzes a "magic angle" effect, a well known in clinical practice artifact of a sudden signal increase in normal tendons and ligaments at the orientation of 55° with respect to the static magnetic field of an MRI scanner. The physical basis of the orientation dependence of the free induction decay is studied in ex-vivo mammalian tissue at the field strength of 2 Tesla. Obtained quantitative measures are related to the model of heterogeneous water phases in the collagen extracellular matrix of tendon. A novel effect of central frequency shift of the water signal is reported and hypothesis on the origin of the effect is put forward. Clinical applications of NMR and MRI constantly benefit from adopting methods and techniques from the field of NMR of liquids, solids and liquid crystals. In the second chapter, a pseudo solid echo technique is evaluated for the purpose of detecting slow motions in the collagen matrix at different hydration and temperatures, at the field strength of 11.74 Tesla (500 MHz). The pseudo solid echo is shown capable in detecting motions on the scale of 10-3-10-6 seconds. 1H spin-lattice relaxation study at different levels of hydration and temperatures is presented in the third chapter. Predictions of the molecular model of collagen hydration are verified at the field strength of 11.74 Tesla (500 MHz) and temperature of 6°C, 26°C and 37°C. In the fourth chapter, an efficient adaptive mesh numerical code is developed on the basis of the octal tree data structure for assessment of the bulk magnetic susceptibility effects. The code allows calculation of the microscopic magnetic field as "seen by the nucleus" for uniformly magnetized

  16. Nuclear magnetic resonance studies of lysine-vasopressin: structural constraints.

    PubMed

    Von Dreele, P H; Brewster, A I; Bovey, F A; Scheraga, H A; Ferger, M F; Du Vigneaud, V

    1971-12-01

    The 220-MHz proton NMR spectra of lysine-vasopressin and some related compounds are examined in deuterated dimethyl sulfoxide to obtain structural information that must be satisfied by any proposed conformation of the molecule. This structural information is in the form of dihedral angles (for rotation about the NH-C(alpha)H bonds) from coupling constants, possible hydrogen bonding of the CONH(2) and backbone amide groups from the temperature-dependence of the chemical shift, and aromatic ring-aromatic ring interaction from the effect of the magnetically anisotropic groups on the chemical shift. PMID:5289251

  17. Cavity- and waveguide-resonators in electron paramagnetic resonance, nuclear magnetic resonance, and magnetic resonance imaging.

    PubMed

    Webb, Andrew

    2014-11-01

    Cavity resonators are widely used in electron paramagnetic resonance, very high field magnetic resonance microimaging and also in high field human imaging. The basic principles and designs of different forms of cavity resonators including rectangular, cylindrical, re-entrant, cavity magnetrons, toroidal cavities and dielectric resonators are reviewed. Applications in EPR and MRI are summarized, and finally the topic of traveling wave MRI using the magnet bore as a waveguide is discussed. PMID:25456314

  18. Anisotropic nuclear magnetic shielding in C sub 60

    SciTech Connect

    Fowler, P.W. ); Lazzeretti, P.; Malagoli, M.; Zansai, R. )

    1991-08-22

    Extrapolation from ab initio coupled Hartree-Fock calculations is used to estimate the anisotropic {sup 13}C nuclear shielding tensor for each site in C{sub 60}. The principal components of the symmetric shielding tensor are 179, 10, and {minus}51 ppm. The derived chemical shifts have the same pattern as those deduced from solid-state NMR measurements, and their mean differs from the experimental shift by less than 4 ppm. The large diamagnetic component is associated with a near-radical local axis and the paramagnetic component with the normal to the local mirror plane.

  19. Nuclear Quadrupole Resonance Studies of the Sorc Sequence and Nuclear Magnetic Resonance Studies of Polymers.

    NASA Astrophysics Data System (ADS)

    Jayakody, Jayakody R. Pemadasa

    1993-01-01

    The behavior of induction signals during steady -state pulse irradiation in ^{14} N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method. Also as part of the NQR work, Cocaine base has been detected using conventional NQR techniques. The experimental results show that SORC detection can be of sufficient sensitivity to form the basis of narcotics screening devices for both mail and airline baggage. A new NMR technique, to obtain the correlation time of the random thermal motion of a polymer at temperatures near the glass transition has been introduced. The temperature dependence is a result of thermal motion. For slow-motion of a polymer chain near the glass transition, the CSA parameter begins to decrease. This motional narrowing can be interpreted to yield the correlation time of the thermal motion. In this work Nitrocellulose isotopically highly enriched with ^{15}N was studied at four different temperatures between 27^ circ and 120^circ Celsius and the correlation times for polymer backbone motions were obtained. Nafion films containing, water (D_2 O and H_2^{17}O) and methanol (CH_3OD, CH _3^{17}OH), have been studied using Deuteron and Oxygen-17 NMR spectroscopy. Glassy behavior of the water domains at low temperature is evidenced by the specific nature of the ^2H NMR lineshapes. Activation energies extracted from ^2H spin-lattice relaxation data on the high temperature side of the T_1 minimum exhibit a steady increase with increasing water content. In spite of a high degree of molecular mobility, angular-dependent spectra of both unstretched and stretched samples reflect considerable anisotropy of the host polymer. Activation volumes corresponding to a specific dynamical

  20. Spin-exchange narrowing in a nuclear magnetic transverse oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Thrasher, Daniel; Bulatowicz, Michael; Walker, Thad

    2015-05-01

    We demonstrate spin exchange narrowing in synchronously pumped Xe NMR. The Xe NMR is driven by spin exchange with Rb atoms whose polarization is square-wave modulated at the Xe NMR frequency. On resonance, the nuclei precess in phase with the Rb polarization. Off resonance, however, the spin-exchange fields from the Rb cause the Xe to develop a static orthogonal spin component. This induces broadening in the NMR line while also dramatically suppressing the phase shift between the precessing Rb and Xe polarizations. We can compensate for this effect by adding an oscillating magnetic field oriented along the optical pumping axis and 180 degrees out of phase with the Rb polarization. This narrows the NMR line width to approximately the T1 limit, and nearly restores the usual relationship between detuning and phase shift. These results suggest the possibility of using the alkali field with appropriate magnetic field feedback along the bias field direction to narrow the NMR linewidth below the usual T1 limit. Support by the NSF and Northrop Grumman Co.

  1. Matrix decompositions of two-dimensional nuclear magnetic resonance spectra.

    PubMed Central

    Havel, T F; Najfeld, I; Yang, J X

    1994-01-01

    Two-dimensional NMR spectra are rectangular arrays of real numbers, which are commonly regarded as digitized images to be analyzed visually. If one treats them instead as mathematical matrices, linear algebra techniques can also be used to extract valuable information from them. This matrix approach is greatly facilitated by means of a physically significant decomposition of these spectra into a product of matrices--namely, S = PAPT. Here, P denotes a matrix whose columns contain the digitized contours of each individual peak or multiple in the one-dimensional spectrum, PT is its transpose, and A is an interaction matrix specific to the experiment in question. The practical applications of this decomposition are considered in detail for two important types of two-dimensional NMR spectra, double quantum-filtered correlated spectroscopy and nuclear Overhauser effect spectroscopy, both in the weak-coupling approximation. The elements of A are the signed intensities of the cross-peaks in a double quantum-filtered correlated spectrum, or the integrated cross-peak intensities in the case of a nuclear Overhauser effect spectrum. This decomposition not only permits these spectra to be efficiently simulated but also permits the corresponding inverse problems to be given an elegant mathematical formulation to which standard numerical methods are applicable. Finally, the extension of this decomposition to the case of strong coupling is given. PMID:8058742

  2. The Trojan Horse Method as a tool to investigate low-energy resonances: the {sup 18}O(p, {alpha}){sup 15}N and {sup 17}O(p, {alpha}){sup 14}N cases

    SciTech Connect

    La Cognata, M.; Sergi, M. L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; Kiss, G.; Lamia, L.; Pizzone, R. G.; Romano, S.; Mukhamedzhanov, A.; Goldberg, V.; Tribble, R.; Coc, A.; Hammache, F.; Sereville, N. de; Tumino, A.

    2010-08-12

    The {sup 18}O(p, {alpha}){sup 15}N and {sup 17}O(p, {alpha}){sup 14}N reactions are of primary importance in several as-trophysical scenarios, including nucleosynthesis inside Asymptotic Giant Branch stars and oxygen and nitrogen isotopic ratios in meteorite grains. They are also key reactions to understand exotic systems such as R-Coronae Borealis stars and novae. Thus, the measurement of their cross sections in the low energy region can be crucial to reduce the nuclear uncertainty on theoretical predictions, because the resonance parameters are poorly determined. The Trojan Horse Method, in its newly developed form particularly suited to investigate low-energy resonances, has been applied to the {sup 2}H({sup 18}O, {alpha}{sup 15}N)n and {sup 2}H({sup 17}O, {alpha}{sup 14}N)n reactions to deduce the {sup 18}O(p, {alpha}){sup 15}N and {sup 17}O(p, {alpha}){sup 14}N cross sections at low energies. Resonances in the {sup 18}O(p, {alpha}){sup 15}N and {sup 17}O(p, {alpha}){sup 14}N excitation functions have been studied and the resonance parameters deduced.

  3. Joint Experimental and Computational 17O and 1H Solid State NMR Study of Ba2In2O4(OH)2 Structure and Dynamics

    PubMed Central

    2015-01-01

    A structural characterization of the hydrated form of the brownmillerite-type phase Ba2In2O5, Ba2In2O4(OH)2, is reported using experimental multinuclear NMR spectroscopy and density functional theory (DFT) energy and GIPAW NMR calculations. When the oxygen ions from H2O fill the inherent O vacancies of the brownmillerite structure, one of the water protons remains in the same layer (O3) while the second proton is located in the neighboring layer (O2) in sites with partial occupancies, as previously demonstrated by Jayaraman et al. (Solid State Ionics2004, 170, 25−32) using X-ray and neutron studies. Calculations of possible proton arrangements within the partially occupied layer of Ba2In2O4(OH)2 yield a set of low energy structures; GIPAW NMR calculations on these configurations yield 1H and 17O chemical shifts and peak intensity ratios, which are then used to help assign the experimental MAS NMR spectra. Three distinct 1H resonances in a 2:1:1 ratio are obtained experimentally, the most intense resonance being assigned to the proton in the O3 layer. The two weaker signals are due to O2 layer protons, one set hydrogen bonding to the O3 layer and the other hydrogen bonding alternately toward the O3 and O1 layers. 1H magnetization exchange experiments reveal that all three resonances originate from protons in the same crystallographic phase, the protons exchanging with each other above approximately 150 °C. Three distinct types of oxygen atoms are evident from the DFT GIPAW calculations bare oxygens (O), oxygens directly bonded to a proton (H-donor O), and oxygen ions that are hydrogen bonded to a proton (H-acceptor O). The 17O calculated shifts and quadrupolar parameters are used to assign the experimental spectra, the assignments being confirmed by 1H–17O double resonance experiments. PMID:26321789

  4. Magnetic-field-induced quadrupole coupling in the nuclear magnetic resonance of noble-gas atoms and molecules

    SciTech Connect

    Manninen, Pekka; Vaara, Juha; Pyykkoe, Pekka

    2004-10-01

    An analytic response theory formulation for the leading-order magnetic field-induced and field-dependent quadrupole splitting in nuclear magnetic resonance spectra is presented and demonstrated with first-principles calculations for {sup 21}Ne, {sup 36}Ar, and {sup 83}Kr in noble gas atoms. The case of molecules was studied for {sup 33}S in the sulphur hexafluoride molecule, as well as for {sup 47/49}Ti, {sup 91}Zr, and {sup 177,179}Hf in group(IV) tetrahalides. According to our calculations, the hitherto experimentally unknown field-induced quadrupole splitting in molecules rises to 10{sup 2} Hz for {sup 177,179}Hf nuclei in HfF{sub 4} and 10{sup 1} Hz for {sup 47/49}Ti in TiCl{sub 4}, and is hence of observable magnitude.

  5. HyReSpect: A broadband fast-averaging spectrometer for nuclear magnetic resonance of magnetic materials

    NASA Astrophysics Data System (ADS)

    Allodi, G.; Banderini, A.; De Renzi, R.; Vignali, C.

    2005-08-01

    We announce the successful development of a homemade frequency-swept nuclear magnetic resonance (NMR) spectrometer entirely designed and built at the University of Parma, optimized for the study of magnetic materials but also offering good performance as a general-purpose instrument for solid-state NMR. The spectrometer features heterodyne-based pulser and receiver with four-quadrant phase shifting and quadrature detection; a 150 MHz digital signal processor as a digital pulser for timing and control functions, capable of triggering events with a resolution of 6.6 ns; a two-channel 12 bit 25MS/s digitizer hosted by a personal computer; and a graphical user interface control program running under Linux, which also integrates external field and temperature controls. The receiver exhibits a flat response from 8 up to 670 MHz, a frequency span suitable for the investigation of magnetic transition metal compounds (V, Co, Mn, Cu), and intrinsic dead time of less than 2μs, as required with the fast-relaxing NMR signals often encountered in magnetic materials. The rf design employing only one external signal generator, and the fast-averaging performance of the system (more than 10 000 repetitions per second), are probably the most remarkable features of our apparatus.

  6. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

    NASA Astrophysics Data System (ADS)

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-01

    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 method 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.

  7. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment.

    PubMed

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    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 method 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. PMID:26979686

  8. Fabrication and Magnetic Properties of Co-Doped TiO2 Powders Studied by Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Ge, Shi-Hui; Wang, Xin-Wei; Kou, Xiao-Ming; Zhou, Xue-Yun; Xi, Li; Zuo, Ya-Lu; Yang, Xiao-Lin; Zhao, Yu-Xuan

    2005-07-01

    Co0.04Ti0.96O2 powders are fabricated by sol-gel method. The structure and magnetic properties are investigated under different annealing conditions systematically with emphasis on the influence of oxygen pressure. Pure anatase structure was acquired for all the samples annealed at 450 degrees C for one hour. The samples annealed in air exhibit evident room-temperature ferromagnetism (RTFM) with a small magnetic moment of 0.029 μB per Co atom and coercivity Hc of 26 Oe, while the samples annealed in vacuum have strong RTFM with a larger magnetic moment of 1.18 μB per Co atom and Hc of 430 Oe. The zero-field spin echo nuclear magnetic resonance spectrum of 59Co is obtained to prove the existence of Co clusters in the latter samples, implying that the Co clusters are responsible for the strong RTFM in the samples annealed in vacuum. No Co cluster could be observed using both XPS and NMR techniques in the samples annealed in air, implying that the RTFM found in these samples is intrinsic.

  9. Methodological aspects in the calculation of parity-violating effects in nuclear magnetic resonance parameters.

    PubMed

    Weijo, Ville; Bast, Radovan; Manninen, Pekka; Saue, Trond; Vaara, Juha

    2007-02-21

    We examine the quantum chemical calculation of parity-violating (PV) electroweak contributions to the spectral parameters of nuclear magnetic resonance (NMR) from a methodological point of view. Nuclear magnetic shielding and indirect spin-spin coupling constants are considered and evaluated for three chiral molecules, H2O2, H2S2, and H2Se2. The effects of the choice of a one-particle basis set and the treatment of electron correlation, as well as the effects of special relativity, are studied. All of them are found to be relevant. The basis-set dependence is very pronounced, especially at the electron correlated ab initio levels of theory. Coupled-cluster and density-functional theory (DFT) results for PV contributions differ significantly from the Hartree-Fock data. DFT overestimates the PV effects, particularly with nonhybrid exchange-correlation functionals. Beginning from third-row elements, special relativity is of importance for the PV NMR properties, shown here by comparing perturbational one-component and various four-component calculations. In contrast to what is found for nuclear magnetic shielding, the choice of the model for nuclear charge distribution--point charge or extended (Gaussian)--has a significant impact on the PV contribution to the spin-spin coupling constants. PMID:17328593

  10. Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials

    DOEpatents

    Kraus, Robert H.; Matlashov, Andrei N.; Espy, Michelle A.; Volegov, Petr L.

    2010-03-30

    An ultra-low magnetic field NMR system can non-invasively examine containers. Database matching techniques can then identify hazardous materials within the containers. Ultra-low field NMR systems are ideal for this purpose because they do not require large powerful magnets and because they can examine materials enclosed in conductive shells such as lead shells. The NMR examination technique can be combined with ultra-low field NMR imaging, where an NMR image is obtained and analyzed to identify target volumes. Spatial sensitivity encoding can also be used to identify target volumes. After the target volumes are identified the NMR measurement technique can be used to identify their contents.

  11. New insights into the bonding arrangements of L- and D-glutamates from solid state 17O NMR

    NASA Astrophysics Data System (ADS)

    Lemaitre, V.; Pike, K. J.; Watts, A.; Anupold, T.; Samoson, A.; Smith, M. E.; Dupree, R.

    2003-03-01

    Magic angle spinning (MAS) from L- and D-glutamic acid-HCl at 14.1 T produces highly structured and very similar NMR spectra. Lines from all 4 oxygen sites are readily distinguished and assigned. These 17O NMR spectra are very different from the previously reported 17O spectrum of the D, L-form presumably because that was a racemic crystal. 17O NMR from L-monosodium glutamate-HCl is very different again requiring the application of double angle rotation and 3 quantum MAS NMR to provide resolution of 5 different sites. Hence high resolution 17O solid state NMR techniques offer possible new insight into biochemical bonding processes.

  12. Nuclear heating, radiation damage, and waste management options for the HYLIFE-II final focus magnets

    SciTech Connect

    Latkowski, J F; Moir, R W; House, P A

    1999-08-09

    Heavy-ion fusion (HIF) designs for inertial fusion energy (XFE) power plants typically require final focusing magnets just outside the reaction chamber and blanket. Due to penetrations within the chamber and blanket, the magnets are exposed to a radiation environment. Although the magnet bores would be sized to avoid line-of-sight irradiation, the magnets still would be susceptible to nuclear heating and radiation damage from neutrons and y-rays. Additionally, the magnets must be included in waste management considerations due to neutron activation. Modified versions of the HYLIFE-II IFE power plant featuring two-sided illumination by arrays of 32 or 96 beams from each side are presented. A simple, point-of-departure quadrupole magnet design is assumed, and a three-dimensional neutronics model is created for the Flibe pocket, first wall, blanket, shield, and final two focusing magnets. This work details state-of-the-art neutronics calculations and shows that the final focus system needs to be included in the economic and environmental considerations for the driver-chamber interface of any HIF IFE power plant design.

  13. Meso-Scale Magnetic Signatures for Nuclear Reactor Steel Irradiation Embrittlement Monitoring

    SciTech Connect

    Suter, Jonathan D.; Ramuhalli, Pradeep; McCloy, John S.; Xu, Ke; Hu, Shenyang Y.; Li, Yulan; Jiang, Weilin; Edwards, Danny J.; Schemer-Kohrn, Alan L.; Johnson, Bradley R.

    2015-03-31

    Verifying the structural integrity of passive components in light-water and advanced reactors will be necessary to ensure safe, long-term operations of the existing U.S. nuclear fleet. This objective can be achieved through nondestructive condition monitoring techniques, which can be integrated with plant operations to quantify the ‘state of health’ of structural materials in real-time. While nondestructive methods for monitoring many classes of degradation (such as fatigue or stress corrosion cracking) are relatively advanced, this is not the case for degradation caused by irradiation. The development of non-destructive evaluation (NDE) technologies for these types of degradation will require advanced materials characterization techniques and tools that enable comprehensive understanding of nuclear reactor material microstructural and behavioral changes under extreme operating environments. Irradiation-induced degradation of reactor steels causes changes in their microstructure that impacts their micro-magnetic properties. In this paper, we describe preliminary results to integrate advanced material characterization techniques with meso-scale computational models to provide an interpretive understanding of the state of degradation in a material. Microstructural data are presented from monocrystalline Fe and are correlated with variable-field magnetic force microscopy and micro-magnetic measurements. In future efforts, microstructural measurements and meso-scale magnetic measurements on thin films will be used to gain insights into the structural state of these materials to study the impact of irradiation on magnetic properties. Preliminary conclusions from these correlations are presented, and next steps described.

  14. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2011-04-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxide (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. This article reviews and illustrates a series of basic concepts relevant to the propagation of the Δ17O of ozone to other reactive or secondary atmospheric species within a photochemical box model. We present results from numerical simulations carried out using the atmospheric chemistry box model CAABA/MECCA to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Using a simplified but realistic tropospheric gas-phase chemistry mechanism, Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the mass-balance equations, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model results confirm that diurnal variations in Δ17O of NOx predicted by the photochemical steady-state relationship during the day match those from the explicit treatment, but not at night. Indeed, the Δ17O of NOx is "frozen" at night as soon as the photolytical lifetime of NOx drops below ca. 10 min. We introduce and quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2, which is of particular relevance to larger-scale simulations of Δ17O where high computational costs cannot be afforded.

  15. Quantitative nuclear magnetic resonance imaging: characterisation of experimental cerebral oedema.

    PubMed Central

    Barnes, D; McDonald, W I; Johnson, G; Tofts, P S; Landon, D N

    1987-01-01

    Magnetic resonance imaging (MRI) has been used quantitatively to define the characteristics of two different models of experimental cerebral oedema in cats: vasogenic oedema produced by cortical freezing and cytotoxic oedema induced by triethyl tin. The MRI results have been correlated with the ultrastructural changes. The images accurately delineated the anatomical extent of the oedema in the two lesions, but did not otherwise discriminate between them. The patterns of measured increase in T1' and T2' were, however, characteristic for each type of oedema, and reflected the protein content. The magnetisation decay characteristics of both normal and oedematous white matter were monoexponential for T1 but biexponential for T2 decay. The relative sizes of the two component exponentials of the latter corresponded with the physical sizes of the major tissue water compartments. Quantitative MRI data can provide reliable information about the physico-chemical environment of tissue water in normal and oedematous cerebral tissue, and are useful for distinguishing between acute and chronic lesions in multiple sclerosis. Images PMID:3572428

  16. Mechanical design parameters for detection of nuclear signals by magnetic resonance force microscopy

    SciTech Connect

    Moore, G.J.; Hanlon, J.A.; Lamartine, B.; Hawley, M.; Solem, J.C.; Signer, S.; Jarmer, J.J.; Penttila, S.; Sillerud, L.O.; Pryputniewicz, R.J.

    1993-10-01

    Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene.

  17. Two-dimensional nuclear magnetic resonance studies of molecular structure in liquids and liquid crystals

    SciTech Connect

    Rucker, S.P.

    1991-07-01

    Magnetic couplings between protons, such as through-space dipole couplings, and scalar J-couplings depend sensitively on the structure of the molecule. Two dimensional nuclear magnetic resonance experiments provide a powerful tool for measuring these couplings, correlating them to specific pairs of protons within the molecule, and calculating the structure. This work discusses the development of NMR methods for examining two such classes of problems -- determination of the secondary structure of flexible molecules in anisotropic solutions, and primary structure of large biomolecules in aqueous solutions. 201 refs., 84 figs., 19 tabs.

  18. Micro-coil detection of nuclear magnetic resonance for nanofluidic samples

    SciTech Connect

    Shibahara, A.; Casey, A.; Lusher, C. P.; Saunders, J.; Aßmann, C.; Schurig, Th.; Drung, D.

    2014-02-15

    We have developed a novel dc SQUID system with a micro-coil input circuit to act as a local probe of quantum matter and nanosystems. The planar niobium micro-coil pickup loop is located remotely from the SQUID, coupled through a superconducting twisted pair. A high degree of coupling between the coil and the region of interest of similar dimensions (up to ∼ 100 microns) can be achieved. We report nuclear magnetic resonance (NMR) measurements to characterise the sensitivity of these coils to {sup 3}He in the gas phase at 4.2 K in a 30 mT magnetic field.

  19. Generation of low-frequency electric and magnetic fields during large- scale chemical and nuclear explosions

    SciTech Connect

    Adushkin, V.V.; Dubinya, V.A.; Karaseva, V.A.; Soloviev, S.P.; Surkov, V.V.

    1995-06-01

    We discuss the main parameters of the electric field in the surface layer of the atmosphere and the results of the investigations of the natural electric field variations. Experimental investigations of the electromagnetic field for explosions in air are presented. Electromagnetic signals generated by underground nuclear and chemical explosions are discussed and explosions for 1976--1991 are listed. Long term anomalies of the earth`s electromagnetic field in the vicinity of underground explosions were also investigated. Study of the phenomenon of the irreversible shock magnetization showed that in the zone nearest to the explosion the quasistatic magnetic field decreases in inverse proportion to the distance.

  20. Nuclear Magnetic Moment of {sup 210}Fr: A Combined Theoretical and Experimental Approach

    SciTech Connect

    Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; Iskrenova-Tchoukova, E.; Safronova, M. S.

    2008-05-02

    We measure the hyperfine splitting of the 9S{sub 1/2} level of {sup 210}Fr, and find a magnetic dipole hyperfine constant A=622.25(36) MHz. The theoretical value, obtained using the relativistic all-order method from the electronic wave function at the nucleus, allows us to extract a nuclear magnetic moment of 4.38(5){mu}{sub N} for this isotope, which represents a factor of 2 improvement in precision over previous measurements. The same method can be applied to other rare isotopes and elements.

  1. A two-axis goniometer for low-temperature nuclear magnetic resonance measurements on single crystals

    NASA Astrophysics Data System (ADS)

    Shiroka, T.; Casola, F.; Mesot, J.; Bachmann, W.; Ott, H.-R.

    2012-09-01

    We report on the construction of a two-axis goniometer intended for low-temperature, single-crystal nuclear magnetic resonance (NMR) measurements. With the use of home-made and commercially available parts, our simple probe-head design achieves good sensitivity, while maintaining a high angular precision and the ability to orient samples also when cooled to liquid helium temperatures. The probe with the goniometer is adapted to be inserted into a commercial 4He-flow cryostat, which fits into a wide-bore superconducting solenoid magnet. Selected examples of NMR measurements illustrate the operation of the device.

  2. Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

    SciTech Connect

    Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

    2014-12-15

    We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR.

  3. Using dual-bacterial denitrification to improve δ15N determinations of nitrates containing mass-independent 17O

    USGS Publications Warehouse

    Coplen, T.B.; Böhlke, J.K.; Casciotti, K.L.

    2004-01-01

    The bacterial denitrification method for isotopic analysis of nitrate using N2O generated from Pseudomonas aureofaciens may overestimate ??15N values by as much as 1-2??? for samples containing atmospheric nitrate because of mass-independent 17O variations in such samples. By analyzing such samples for ??15N and ??18O using the denitrifier Pseudomonas chlororaphis, one obtains nearly correct ??15N values because oxygen in N 2O generated by P. chlororaphis is primarily derived from H 2O. The difference between the apparent ??15N value determined with P. aureofaciens and that determined with P. chlororaphis, assuming mass-dependent oxygen isotopic fractionation, reflects the amount of mass-independent 17O in a nitrate sample. By interspersing nitrate isotopic reference materials having substantially different ?? 18O values with samples, one can normalize oxygen isotope ratios and determine the fractions of oxygen in N2O derived from the nitrate and from water with each denitrifier. This information can be used to improve ??15N values of nitrates having excess 17O. The same analyses also yield estimates of the magnitude of 17O excess in the nitrate (expressed as ??17O) that may be useful in some environmental studies. The 1-?? uncertainties of ??15N, ??18O and ??17O measurements are ??0.2, ??0.3 and ??5???, respectively. Copyright ?? 2004 John Wiley & Sons, Ltd.

  4. Solid-State (17)O NMR of Oxygen-Nitrogen Singly Bonded Compounds: Hydroxylammonium Chloride and Sodium Trioxodinitrate (Angeli's Salt).

    PubMed

    Lu, Jiasheng; Kong, Xianqi; Terskikh, Victor; Wu, Gang

    2015-07-23

    We report a solid-state NMR study of (17)O-labeled hydroxylammonium chloride ([H(17)O-NH3]Cl) and sodium trioxodinitrate monohydrate (Na2[(17)ONNO2]·H2O, Angeli's salt). The common feature in these two compounds is that they both contain oxygen atoms that are singly bonded to nitrogen. For this class of oxygen-containing functional groups, there is very limited solid-state (17)O NMR data in the literature. In this work, we experimentally measured the (17)O chemical shift and quadrupolar coupling tensors. With the aid of plane-wave DFT computation, the (17)O NMR tensor orientations were determined in the molecular frame of reference. We found that the characteristic feature of an O-N single bond is that the (17)O nucleus exhibits a large quadrupolar coupling constant (13-15 MHz) but a rather small chemical shift anisotropy (100-250 ppm), in sharp contrast with the nitroso (O═N) functional group for which both quantities are very large (e.g., 16 MHz and 3000 ppm, respectively). PMID:26107984

  5. Nuclear magnetic resonance imaging and spectroscopy of human brain function.

    PubMed Central

    Shulman, R G; Blamire, A M; Rothman, D L; McCarthy, G

    1993-01-01

    The techniques of in vivo magnetic resonance (MR) imaging and spectroscopy have been established over the past two decades. Recent applications of these methods to study human brain function have become a rapidly growing area of research. The development of methods using standard MR contrast agents within the cerebral vasculature has allowed measurements of regional cerebral blood volume (rCBV), which are activity dependent. Subsequent investigations linked the MR relaxation properties of brain tissue to blood oxygenation levels which are also modulated by consumption and blood flow (rCBF). These methods have allowed mapping of brain activity in human visual and motor cortex as well as in areas of the frontal lobe involved in language. The methods have high enough spatial and temporal sensitivity to be used in individual subjects. MR spectroscopy of proton and carbon-13 nuclei has been used to measure rates of glucose transport and metabolism in the human brain. The steady-state measurements of brain glucose concentrations can be used to monitor the glycolytic flux, whereas subsequent glucose metabolism--i.e., the flux into the cerebral glutamate pool--can be used to measure tricarboxylic acid cycle flux. Under visual stimulation the concentration of lactate in the visual cortex has been shown to increase by MR spectroscopy. This increase is compatible with an increase of anaerobic glycolysis under these conditions as earlier proposed from positron emission tomography studies. It is shown how MR spectroscopy can extend this understanding of brain metabolism. Images Fig. 1 Fig. 2 Fig. 3 PMID:8475050

  6. Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

    SciTech Connect

    Casadei, Cecilia

    2011-01-01

    The aim of the present thesis is to investigate the local magnetic properties of homometallic Cr8 antiferromagnetic (AFM) ring and the changes occurring by replacing one Cr3+ ion with diamagnetic Cd2+ (Cr7Cd) and with Ni2+ (Cr7Ni). In the heterometallic ring a redistribution of the local magnetic moment is expected in the low temperature ground state. We have investigated those changes by both 53Cr-NMR and 19F-NMR. We have determined the order of magnitude of the transferred hyperfine coupling constant 19F - M+ where M+ = Cr3+, Ni2+ in the different rings. This latter result gives useful information about the overlapping of the electronic wavefunctions involved in the coordinative bond.

  7. Nuclear Magnetic Resonance (NMR) analysis of a Kel-F resin and lacquer

    NASA Astrophysics Data System (ADS)

    Rutenberg, A. C.

    1985-08-01

    Proton, carbon, and fluorine nuclear magnetic resonance (NMR) spectroscopy has been used at the Oak Ridge Y-12 Plant to determine the concentration of various species present in Kel-F 800 resin and its lacquers. Nuclear magnetic resonance (NMR) spectroscopy has been used to characterize Kel-F 800 resin and to measure the various chemical species present in a lacquer based on this resin. Proton NMR spectroscopy was used to measure the ratio of ethyl acetate to xylenes and to estimate the vinylidene fluoride content of the resin. Fluorine NMR spectroscopy was used to determine the water and ethanol content of the lacquer as well as some of its components. Fluorine NMR spectroscopy was also used to estimate the amount of perfluorodecanoate emulsifier present in the Kel-F resin. Carbon-13 NMR spectroscopy was used to determine the isomeric composition of various batches of xylenes and as an alternate method for measuring the vinylidene fluoride content of the resin.

  8. NMR-based structural biology enhanced by dynamic nuclear polarization at high magnetic field.

    PubMed

    Koers, Eline J; van der Cruijsen, Elwin A W; Rosay, Melanie; Weingarth, Markus; Prokofyev, Alexander; Sauvée, Claire; Ouari, Olivier; van der Zwan, Johan; Pongs, Olaf; Tordo, Paul; Maas, Werner E; Baldus, Marc

    2014-11-01

    Dynamic nuclear polarization (DNP) has become a powerful method to enhance spectroscopic sensitivity in the context of magnetic resonance imaging and nuclear magnetic resonance spectroscopy. We show that, compared to DNP at lower field (400 MHz/263 GHz), high field DNP (800 MHz/527 GHz) can significantly enhance spectral resolution and allows exploitation of the paramagnetic relaxation properties of DNP polarizing agents as direct structural probes under magic angle spinning conditions. Applied to a membrane-embedded K(+) channel, this approach allowed us to refine the membrane-embedded channel structure and revealed conformational substates that are present during two different stages of the channel gating cycle. High-field DNP thus offers atomic insight into the role of molecular plasticity during the course of biomolecular function in a complex cellular environment. PMID:25284462

  9. Measurement of conductivity and permittivity on samples sealed in nuclear magnetic resonance tubes

    SciTech Connect

    Huang, W.; Angell, C. A.; Yarger, J. L.; Richert, R.

    2013-07-15

    We present a broadband impedance spectroscopy instrument designed to measure conductivity and/or permittivity for samples that are sealed in glass tubes, such as the standard 5 mm tubes used for nuclear magnetic resonance experiments. The calibrations and corrections required to extract the dielectric properties of the sample itself are outlined. It is demonstrated that good estimates of the value of dc-conductivity can be obtained even without correcting for the effects of glass or air on the overall impedance. The approach is validated by comparing data obtained from samples sealed in nuclear magnetic resonance tubes with those from standard dielectric cells, using glycerol and butylmethylimidazolium-hexafluorophosphate as respective examples of a molecular and an ionic liquid. This instrument and approach may prove useful for other studies of permittivity and conductivity where contact to the metal electrodes or to the ambient atmosphere needs to be avoided.

  10. 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.

  11. Effect of the {delta} meson on the instabilities of nuclear matter under strong magnetic fields

    SciTech Connect

    Rabhi, A.; Providencia, C.; Da Providencia, J.

    2009-08-15

    We study the influence of the isovector-scalar meson on the spinodal instabilities and the distillation effect in asymmetric nonhomogenous nuclear matter under strong magnetic fields of the order of 10{sup 18}-10{sup 19} G. Relativistic nuclear models both with constant couplings (NLW) and with density-dependent parameters (DDRH) are considered. A strong magnetic field can have large effects on the instability regions giving rise to bands of instability and wider unstable regions. It is shown that for neutron-rich matter the inclusion of the {delta} meson increases the size of the instability region for NLW models and decreases it for the DDRH models. The effect of the {delta} meson on the transition density to homogeneous {beta}-equilibrium matter is discussed. The DDRH{delta} model predicts the smallest transition pressures, about half the values obtained for NL{delta}.

  12. Low magnetic field dynamic nuclear polarization using a single-coil two-channel probe

    SciTech Connect

    TonThat, D.M.; Augustine, M.P.; Pines, A.; Clarke, J. |

    1997-03-01

    We describe the design and construction of a single-coil, two-channel probe for the detection of low-field magnetic resonance using dynamic nuclear polarization (DNP). The high-frequency channel of the probe, which is used to saturate the electron spins, is tuned to the electron Larmor frequency, 75 MHz at 2.7 mT, and matched to 50 {Omega}. Low-field, {sup 1}H nuclear magnetic resonance (NMR) is detected through the second, low-frequency channel at frequencies {lt}1 MHz. The performance of the probe was tested by measuring the DNP of protons in a manganese (II) chloride solution at 2.7 mT. At the proton NMR frequency of 120 kHz, the signal amplitude was enhanced over the value without DNP by a factor of about 200. {copyright} {ital 1997 American Institute of Physics.}

  13. 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

  14. Measurement of conductivity and permittivity on samples sealed in nuclear magnetic resonance tubes

    NASA Astrophysics Data System (ADS)

    Huang, W.; Angell, C. A.; Yarger, J. L.; Richert, R.

    2013-07-01

    We present a broadband impedance spectroscopy instrument designed to measure conductivity and/or permittivity for samples that are sealed in glass tubes, such as the standard 5 mm tubes used for nuclear magnetic resonance experiments. The calibrations and corrections required to extract the dielectric properties of the sample itself are outlined. It is demonstrated that good estimates of the value of dc-conductivity can be obtained even without correcting for the effects of glass or air on the overall impedance. The approach is validated by comparing data obtained from samples sealed in nuclear magnetic resonance tubes with those from standard dielectric cells, using glycerol and butylmethylimidazolium-hexafluorophosphate as respective examples of a molecular and an ionic liquid. This instrument and approach may prove useful for other studies of permittivity and conductivity where contact to the metal electrodes or to the ambient atmosphere needs to be avoided.

  15. Quantitative constraints on the 17O-excess (Δ17O) signature of surface ozone: Ambient measurements from 50°N to 50°S using the nitrite-coated filter technique

    NASA Astrophysics Data System (ADS)

    Vicars, William C.; Savarino, Joël

    2014-06-01

    The unique and distinctive 17O-excess (Δ17O) of ozone (O3) provides a conservative tracer for oxidative processes in both modern and paleo-atmospheres and has acted as the primary driver of theoretical and experimental research into non-mass-dependent fractionation (NMDF) for over three decades. However, due to the inherent complexity of extracting O3 from ambient air, the existing observational dataset for tropospheric O3 isotopic composition remains quite small. Recent analytical developments have provided a robust and reliable means for determining Δ17O(O3)trans., the transferrable Δ17O signature of ozone in the troposphere (Vicars et al., 2012). We have employed this new methodology in a systematic investigation of the spatial and seasonal features of Δ17O(O3)trans. in two separate field campaigns: a weekly sampling effort at our laboratory in Grenoble, France (45°N) throughout 2012 (n = 47) and a four-week campaign onboard the Research Vessel (R/V) Polarstern along a latitudinal transect from 50°S to 50°N in the Atlantic Ocean (n = 30). The bulk 17O-excess of ozone, denoted Δ17O(O3)bulk, exhibited mean (±1σ) values of 26.2 ± 1.3‰ (Δ17O(O3)trans. = 39.3 ± 2.0‰) and 25.9 ± 1.1‰ (Δ17O(O3)trans. = 38.8 ± 1.6‰) for the Grenoble and R/V Polarstern collections, respectively. This range of values is in excellent quantitative agreement with the two previous studies of ozone triple-isotope composition, which have yielded mean (±1σ) Δ17O(O3)bulk values of 25.4 ± 9.0‰ (n = 89). However, the magnitude of variability detected in the present study is much smaller than that formerly reported. In fact, the standard deviation of Δ17O(O3)bulk in each new dataset is lower than the uncertainty previously estimated for the filter technique (±1.7‰), indicating a low level of natural spatial and temporal variation in the 17O-excess of surface ozone. For instance, no clear temporal pattern in Δ17O(O3) is evident in the annual record from Grenoble

  16. Revealing the climate of snowball Earth from Δ17O systematics of hydrothermal rocks

    PubMed Central

    Herwartz, Daniel; Pack, Andreas; Krylov, Dmitri; Xiao, Yilin; Muehlenbachs, Karlis; Sengupta, Sukanya; Di Rocco, Tommaso

    2015-01-01

    The oxygen isotopic composition of hydrothermally altered rocks partly originates from the interacting fluid. We use the triple oxygen isotope composition (17O/16O, 18O/16O) of Proterozoic rocks to reconstruct the 18O/16O ratio of ancient meteoric waters. Some of these waters have originated from snowball Earth glaciers and thus give insight into the climate and hydrology of these critical intervals in Earth history. For a Paleoproterozoic [∼2.3–2.4 gigayears ago (Ga)] snowball Earth, δ18O = −43 ± 3‰ is estimated for pristine meteoric waters that precipitated at low paleo-latitudes (≤35°N). Today, such low 18O/16O values are only observed in central Antarctica, where long distillation trajectories in combination with low condensation temperatures promote extreme 18O depletion. For a Neoproterozoic (∼0.6–0.7 Ga) snowball Earth, higher meltwater δ18O estimates of −21 ± 3‰ imply less extreme climate conditions at similar paleo-latitudes (≤35°N). Both estimates are single snapshots of ancient water samples and may not represent peak snowball Earth conditions. We demonstrate how 17O/16O measurements provide information beyond traditional 18O/16O measurements, even though all fractionation processes are purely mass dependent. PMID:25870269

  17. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  18. Revealing the climate of snowball Earth from Δ17O systematics of hydrothermal rocks.

    PubMed

    Herwartz, Daniel; Pack, Andreas; Krylov, Dmitri; Xiao, Yilin; Muehlenbachs, Karlis; Sengupta, Sukanya; Di Rocco, Tommaso

    2015-04-28

    The oxygen isotopic composition of hydrothermally altered rocks partly originates from the interacting fluid. We use the triple oxygen isotope composition ((17)O/(16)O, (18)O/(16)O) of Proterozoic rocks to reconstruct the (18)O/(16)O ratio of ancient meteoric waters. Some of these waters have originated from snowball Earth glaciers and thus give insight into the climate and hydrology of these critical intervals in Earth history. For a Paleoproterozoic [∼2.3-2.4 gigayears ago (Ga)] snowball Earth, δ(18)O = -43 ± 3‰ is estimated for pristine meteoric waters that precipitated at low paleo-latitudes (≤35°N). Today, such low (18)O/(16)O values are only observed in central Antarctica, where long distillation trajectories in combination with low condensation temperatures promote extreme (18)O depletion. For a Neoproterozoic (∼0.6-0.7 Ga) snowball Earth, higher meltwater δ(18)O estimates of -21 ± 3‰ imply less extreme climate conditions at similar paleo-latitudes (≤35°N). Both estimates are single snapshots of ancient water samples and may not represent peak snowball Earth conditions. We demonstrate how (17)O/(16)O measurements provide information beyond traditional (18)O/(16)O measurements, even though all fractionation processes are purely mass dependent. PMID:25870269

  19. 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.

  20. High-Resolution Proton Nuclear Magnetic Resonance Analysis of Metastatic Cancer Cells

    NASA Astrophysics Data System (ADS)

    Mountford, Carolyn E.; Wright, Lesley C.; Holmes, Kerry T.; MacKinnon, Wanda B.; Gregory, Patricia; Fox, Richard M.

    1984-12-01

    High-resolution proton nuclear magnetic resonance (NMR) studies of intact cancer cells revealed differences between cells with the capacity to metastasize and those that produce locally invasive tumors. The NMR resonances that characterize the metastatic cells were associated with an increased ratio of cholesterol to phospholipid and an increased amount of plasma membrane--bound cholesterol ester. High-resolution NMR spectroscopy could therefore be used to assess the metastatic potential of primary tumors.

  1. Nuclear magnetic resonance studies of granular flows: Technical progress report, quarter ending 09/30/93

    SciTech Connect

    Not Available

    1993-10-27

    This Technical Progress Report for the quarter ending 09/30/93 describes work on two tasks which are part of nuclear magnetic resonance studies of granular flows. (1) Research has been directed toward improving concentration measurements under reasonably fast conditions. (2) The process continues of obtaining comprehensive velocity, concentration, and diffusion information at several angular velocities of the cylinder for seeds (mustard, sesame, and sunflower seeds) flowing in a half-filled cylinder.

  2. Theory and applications of maps on SO(3) in nuclear magnetic resonance

    SciTech Connect

    Cho, H.M.

    1987-02-01

    Theoretical approaches and experimental work in the design of multiple pulse sequences in Nuclear Magnetic Resonance (NMR) are the subjects of this dissertation. Sequences of discrete pulses which reproduce the nominal effect of single pulses, but over substantially broader, narrower, or more selective ranges of transition frequencies, radiofrequency field amplitudes, and spin-spin couplings than the single pulses they replace, are developed and demonstrated. 107 refs., 86 figs., 6 tabs.

  3. Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments

    NASA Astrophysics Data System (ADS)

    Tang, Yiqiao; Hürlimann, Martin; Mandal, Soumyajit; Paulsen, Jeffrey; Song, Yi-Qiao

    2014-02-01

    A coaxial nuclear magnetic resonance (NMR) probe is built to measure diffusion and relaxation properties of liquid samples. In particular, we demonstrate the acquisition of two-dimensional (2D) distribution functions (T1-T2 and diffusion-T2), essential for fluids characterization. The compact design holds promise for miniaturization, thus enabling the measurement of molecular diffusion that is inaccessible to conventional micro-NMR setups. Potential applications range from crude oil characterization to biomolecular screening and detections.

  4. Fetal imaging by nuclear magnetic resonance: a study in goats: work in progress

    SciTech Connect

    Foster, M.A.; Knight, C.H.; Rimmington, J.E.; Mallard, J.R.

    1983-10-01

    Nuclear magnetic resonance proton imaging was used to obtain images of goat fetuses in utero. The long T1 relaxation time of amniotic fluid makes it appear black on proton density images when examined using the Aberdeen imager, and so allows very good discrimination of the position and structure of the fetus. Some fetal internal tissues can be seen on T1 images. These findings suggest that NMR imaging has great potential in pregnancy studies.

  5. Spatial aspects of nuclear magnetic resonance spectroscopy: Static and radio-frequency magnetic field gradients in principle and practice

    NASA Astrophysics Data System (ADS)

    Sodickson, Aaron David

    All nuclear magnetic resonance (NMR) measurements are influenced by the spatial distribution of spin properties across the sample volume. This thesis presents a general theoretical treatment of spatial phenomena in NMR along with a number of experimental explorations. A generalized k space formalism is described which lends physical insight into the spatial modulations underlying a wide variety of NMR experiments. The approach involves a Fourier decomposition of spin coherences into a set of basis functions that most naturally describes the evolution of the system under field gradients and RF pulses. It provides a straightforward physical interpretation of the sample's spatial behavior while simplifying the calculation of analytical results for any signal pathway of interest. The formalism is applied to a diverse range of NMR experiments, including imaging, echo experiments, flow and diffusion measurements, selective excitation sequences, and multiple quantum coherence pathway selection techniques. A modification of the BIRD and TANGO sequences is presented which incorporates RF gradients to eliminate the net magnetization from uncoupled spins, while completely preserving magnetization with the proper scalar-coupling constant. The spatial variation of the B1 field strength-here due to the residual field inhomogeneity of a nominally homogeneous coil-causes dephasing of the uncoupled line while refocussing the desired magnetization in a rotary echo. The sequence is demonstrated for selective excitation of the satellites in a chloroform sample, yielding suppression of the uncoupled magnetization by a factor of approximately 800. A simplified approach to shimming for a high resolution magic angle spinning (MAS) probe is developed. Correction fields of the desired symmetry about the sample's spinning axis are derived as linear combinations of the usual lab-frame spherical harmonic shim-field geometries. The effects of sample spinning are incorporated which further

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

    PubMed

    Yoder, Jacob; Malone, Michael W; Espy, Michelle A; Sevanto, Sanna

    2014-09-01

    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 for 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. PMID:25273775

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

    SciTech Connect

    Yoder, Jacob; Malone, Michael W.; Espy, Michelle A.; Sevanto, Sanna

    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 for 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.

  8. A nuclear magnetic resonance probe of group IV clathrates

    NASA Astrophysics Data System (ADS)

    Gou, Weiping

    The clathrates feature large cages of silicon, germanium, or tin, with guest atoms in the cage centers. The group IV clathrates are interesting because of their thermoelectric efficiency, and their glasslike thermal conductivity at low temperatures. Clathrates show a variety of properties, and the motion of cage center atoms is not well understood. In Sr8Ga16Ge30, we found that the slow atomic motion in the order 10-5 s is present in this system, which is much slower than what would be expected for standard atomic dynamics. NMR studies of Sr8Ga16Ge30 showed that Knight shift and T1 results are consistent with low density metallic behavior. The lineshapes exhibit changes consistent with motional narrowing at low temperatures, and this indicates unusually slow hopping rates. To further investigate this behavior, we made a series of measurements using the Carr-Purcell-Meiboom-Gill NMR sequence. Fitting the results to a hopping model yielded an activation energy of 4.6 K. We can understand all of our observations in terms of non-resonant atomic tunneling between asymmetric sites within the cages, in the presence of disorder. For Ba8Ga16Ge30, the relaxation behavior (T1) deviates from the Korringa relation, and the Knight shift and linewidth change with temperature. Those results could be explained by carrier freezout, and the development of a dilute set of magnetic moments due to these localized carriers. For Ba8Ga 16Ge30 samples made from Ga flux, we observed different T1 and Knight shift behavior as compared to n type material. This is due to the differences in carrier type among these different samples. The p type sample has a smaller Knight shift and a slower relaxation rate than n type samples made with the stoichiometric ratio, which is consistent with a change in orbital symmetry between the conduction and valence bands. WDS study for Ba8Al10Ge36 showed the existence of vacancies in the Al-deficient samples, which results in some degree of ordering of Al

  9. Separation Nanotechnology of Diethylenetriaminepentaacetic Acid Bonded Magnetic Nanoparticles for Spent Nuclear Fuel

    SciTech Connect

    Kaur, Maninder; Johnson, Andrew; Tian, Guoxin; Jiang, Weilin; Rao, Linfeng; Paszczynski, Andrzej; Qiang, You

    2013-01-01

    A nanomagnetic separation method based on Diethylenetriaminepentaacetic acid (DTPA) conjugated with magnetic nanoparticles (MNPs) is studied for application in spent nuclear fuel separation. The high affinity of DTPA towards actinides aids in separation from the highly acidic medium of nuclear waste. The solubility and magnetization of particles at low pH is protected by encapsulating them in silica layer. Surface functionalization of silica coated particles with polyamines enhances the loading capacity of the chelators on MNPs. The particles were characterized before and after surface modification using transmission electron microscopy (TEM), helium ion microscopy (HIM), Fourier transform-infrared (FT-IR) spectrometry, and X-ray diffractometry. The coated and uncoated samples were studied using vibrating sample magnetometer (VSM) to understand the change in magnetic properties due to the influence of the surface functionalization. The hydrodynamic size and surface charge of the particles are investigated using Dynamic Light Scattering (DLS). The uptake behavior of Am(III), Pu(IV), U(VI), and Np(V) from 0.1M NaNO3 solution was investigated. The sorption result shows the strong affinity of DTPA towards Am(III) and Pu(IV) by extracting 97% and 80% of actinides, respectively. The high removal efficiency and fast uptake of actinides make the chelator conjugated MNPs an effective method for spent nuclear fuel separation.

  10. 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. PMID:27265668

  11. (83)Kr nuclear magnetic moment in terms of that of (3)He.

    PubMed

    Makulski, Włodzimierz

    2014-08-01

    High resolution NMR spectroscopy was applied to precisely determine the (83)Kr nuclear magnetic dipole moment on the basis of new results available for nuclear magnetic shielding in krypton and helium-3 atoms. Small amounts of (3)He as the solutes and (83)Kr as the buffer gas were observed in (3)He and (83)Kr NMR spectra at the constant external field, B0 = 11.7578 T. In each case, the resonance frequencies (ν(He) and ν(Kr)) were linearly dependent on the density of gaseous solvent. The extrapolation of experimental points to the zero density of gaseous krypton allowed for the evaluation of both resonance frequencies free from intermolecular interactions. By combining these measurements with the recommended (83)Kr chemical shielding value, the nuclear magnetic moment could be determined with much better precision than ever before, μ((83)Kr) = -0.9707297(32)μN, with the improvement due to the greater accuracy of the spectral data. PMID:24842240

  12. Nuclear relaxation in an electric field enables the determination of isotropic magnetic shielding

    NASA Astrophysics Data System (ADS)

    Garbacz, Piotr

    2016-08-01

    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 205Tl nucleus in a Pt-Tl bonded complex, Pt(CN)5Tl, the transverse relaxation rate induced by the electric field is of the order of 1 s-1 at E = 5 kV/mm and B = 10 T.

  13. Superconducting quantum interference device microsusceptometer balanced over a wide bandwidth for nuclear magnetic resonance applications

    SciTech Connect

    Vinante, A. Falferi, P.; Mezzena, R.

    2014-10-15

    Superconducting Quantum Interference Device (SQUID) microsusceptometers have been widely used to study magnetic properties of materials at microscale. As intrinsically balanced devices, they could also be exploited for direct SQUID-detection of nuclear magnetic resonance (NMR) from micron sized samples, or for SQUID readout of mechanically detected NMR from submicron sized samples. Here, we demonstrate a double balancing technique that enables achievement of very low residual imbalance of a SQUID microsusceptometer over a wide bandwidth. In particular, we can generate ac magnetic fields within the SQUID loop as large as 1 mT, for frequencies ranging from dc up to a few MHz. As an application, we demonstrate direct detection of NMR from {sup 1}H spins in a glycerol droplet placed directly on top of the 20 μm SQUID loops.

  14. Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

    SciTech Connect

    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 {sup 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.

  15. Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    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. 1H, 23Na, 27Al, 69Ga, and 71Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.

  16. First evidence of detecting surface nuclear magnetic resonance signals using a compact B-field sensor

    NASA Astrophysics Data System (ADS)

    Davis, Aaron C.; Dlugosch, Raphael; Queitsch, Matthias; Macnae, James C.; Stolz, Ronny; Müller-Petke, Mike

    2014-06-01

    The noninvasive detection and characterization of subsurface aquifer structures demands geophysical techniques. Surface nuclear magnetic resonance (SNMR) is the only technique that is directly sensitive to hydrogen protons and, therefore, allows for unambiguous detection of subsurface water. Traditionally, SNMR utilizes large surface coils for both transmitting excitation pulses and recording the groundwater response. Recorded data are thus a voltage induced by the time derivative of the secondary magnetic field. For the first time, we demonstrate that the secondary magnetic field in a SNMR experiment can be directly detected using a superconducting quantum interference device magnetometer. Conducting measurements at a test site in Germany, we demonstrate not only the ability to detect SNMR signals on the order of femtoTesla but also we are able to satisfy the observed data by inverse modeling. This is expected to open up completely new applications for this exciting technology.

  17. Meso-scale magnetic signatures for nuclear reactor steel irradiation embrittlement monitoring

    NASA Astrophysics Data System (ADS)

    Suter, J. D.; Ramuhalli, P.; McCloy, J. S.; Xu, K.; Hu, S.; Li, Y.; Jiang, W.; Edwards, D. J.; Schemer-Kohrn, A. L.; Johnson, B. R.

    2015-03-01

    Verifying the structural integrity of passive components in light water and advanced reactors will be necessary to ensure safe, long-term operations of the existing U.S. nuclear fleet. This objective can be achieved through nondestructive condition monitoring techniques, which can be integrated with plant operations to quantify the "state of health" of structural materials in real-time. While nondestructive methods for monitoring many classes of degradation (such as fatigue or stress corrosion cracking) are relatively advanced, this is not the case for degradation caused by irradiation. The development of nondestructive evaluation technologies for these types of degradation will require advanced materials characterization techniques and tools that enable comprehensive understanding of nuclear reactor material microstructural and behavioral changes under extreme operating environments. Irradiation-induced degradation of reactor steels causes changes in their microstructure that impacts their micro-magnetic properties. In this paper, we describe preliminary results of integrating advanced material characterization techniques with meso-scale computational models. In the future, this will help to provide an interpretive understanding of the state of degradation in structural materials. Microstructural data are presented from monocrystalline Fe and are correlated with variable-field magnetic force microscopy and micro-magnetic measurements. Ongoing research is focused on extending the measurements and models on thin films to gain insights into the structural state of irradiated materials and the resulting impact on magnetic properties. Preliminary conclusions from these correlations are presented, and next steps described.

  18. Heterometallic Cu(II)-Dy(III) Clusters of Different Nuclearities with Slow Magnetic Relaxation.

    PubMed

    Modak, Ritwik; Sikdar, Yeasin; Cosquer, Goulven; Chatterjee, Sudipta; Yamashita, Masahiro; Goswami, Sanchita

    2016-01-19

    The synthesis, structures, and magnetic properties of two heterometallic Cu(II)-Dy(III) clusters are reported. The first structural motif displays a pentanuclear Cu(II)4Dy(III) core, while the second one reveals a nonanuclear Cu(II)6Dy(III)3 core. We employed o-vanillin-based Schiff base ligands combining o-vanillin with 3-amino-1-propanol, H2vap, (2-[(3-hydroxy-propylimino)-methyl]-6-methoxy-phenol), and 2-aminoethanol, H2vae, (2-[(3-hydroxy-ethylimino)-methyl]-6-methoxy-phenol). The differing nuclearities of the two clusters stem from the choice of imino alcohol arm in the Schiff bases, H2vap and H2vae. This work is aimed at broadening the diversity of Cu(II)-Dy(III) clusters and to perceive the consequence of changing the length of the alcohol arm on the nuclearity of the cluster, providing valuable insight into promising future synthetic directions. The underlying topological entity of the pentanuclear Cu4Dy cluster is reported for the first time. The investigation of magnetic behaviors of 1 and 2 below 2 K reveals slow magnetic relaxation with a significant influence coming from the variation of the alcohol arm affecting the nature of magnetic interactions. PMID:26702645

  19. Meso-scale magnetic signatures for nuclear reactor steel irradiation embrittlement monitoring

    SciTech Connect

    Suter, J. D. Ramuhalli, P. Hu, S.; Li, Y.; Jiang, W.; Edwards, D. J.; Schemer-Kohrn, A. L.; Johnson, B. R.; McCloy, J. S. Xu, K.

    2015-03-31

    Verifying the structural integrity of passive components in light water and advanced reactors will be necessary to ensure safe, long-term operations of the existing U.S. nuclear fleet. This objective can be achieved through nondestructive condition monitoring techniques, which can be integrated with plant operations to quantify the “state of health” of structural materials in real-time. While nondestructive methods for monitoring many classes of degradation (such as fatigue or stress corrosion cracking) are relatively advanced, this is not the case for degradation caused by irradiation. The development of nondestructive evaluation technologies for these types of degradation will require advanced materials characterization techniques and tools that enable comprehensive understanding of nuclear reactor material microstructural and behavioral changes under extreme operating environments. Irradiation-induced degradation of reactor steels causes changes in their microstructure that impacts their micro-magnetic properties. In this paper, we describe preliminary results of integrating advanced material characterization techniques with meso-scale computational models. In the future, this will help to provide an interpretive understanding of the state of degradation in structural materials. Microstructural data are presented from monocrystalline Fe and are correlated with variable-field magnetic force microscopy and micro-magnetic measurements. Ongoing research is focused on extending the measurements and models on thin films to gain insights into the structural state of irradiated materials and the resulting impact on magnetic properties. Preliminary conclusions from these correlations are presented, and next steps described.

  20. A Nuclear Magnetic Resonance Force Microscope for Micron-scale Liquids

    NASA Astrophysics Data System (ADS)

    Giraldo, Felipe; Paster, Jeremy W.; Tennant, Daniel M.; Markert, John T.

    2015-03-01

    We have designed and constructed a Nuclear Magnetic Resonance Force Microscopy (NMRFM) probe for the analysis of liquid and soft matter samples. This NRMFM probe uses a magnet-on-cantilever geometry and is equipped with dual x- y- z piezoelectric motion stages, for micron-step coarse positioning and sub-nanometer fine positioning of both the laser interferometer and the sample with respect to the cantilever, permitting three-dimensional scanning-mode detection of nuclear magnetism. The probe keeps the cantilever detector in high vacuum, maintaining a high Q, while the local NMR properties of nearby aqueous samples in glass microtubes are measured. The entire probe head fits in either a 3.5-cm bore magnet or in an electromagnet with a similarly small gap. We plan to demonstrate the ability to scan and distinguish microscale NMR properties using a copper sulfate solution with concentrations in the 2-20 millimolar range, thus providing dynamical imaging of regions with differing longitudinal relaxation times, T1. This concentration range will permit us to compare the conventional saturation-recovery pulse sequence with a more efficient single-pulse detection, possible when T1 is comparable to or less than the duration of the modified cyclic-adiabatic-inversion pulse.

  1. Electric quadrupole polarizabilities of nuclear magnetic shielding in some small molecules.

    PubMed

    Ferraro, M B; Caputo, M C; Pagola, G I; Lazzeretti, P

    2008-01-28

    Computational procedures, based on (i) the Ramsey common origin approach and (ii) the continuous transformation of the origin of the quantum mechanical current density-diamagnetic zero (CTOCD-DZ), were applied at the Hartree-Fock level to determine electric quadrupole polarizabilities of nuclear magnetic shielding for molecules in the presence of a nonuniform electric field with a uniform gradient. The quadrupole polarizabilities depend on the origin of the coordinate system, but values of the magnetic field induced at a reference nucleus, determined via the CTOCD-DZ approach, are origin independent for any calculations relying on the algebraic approximation, irrespective of size and quality of the (gaugeless) basis set employed. On the other hand, theoretical estimates of the induced magnetic field obtained by single-origin methods are translationally invariant only in the limit of complete basis sets. Calculations of electric quadrupole polarizabilities of nuclear magnetic shielding are reported for H(2), HF, H(2)O, NH(3), and CH(4) molecules. PMID:18247940

  2. Electric quadrupole polarizabilities of nuclear magnetic shielding in some small molecules

    NASA Astrophysics Data System (ADS)

    Ferraro, M. B.; Caputo, M. C.; Pagola, G. I.; Lazzeretti, P.

    2008-01-01

    Computational procedures, based on (i) the Ramsey common origin approach and (ii) the continuous transformation of the origin of the quantum mechanical current density-diamagnetic zero (CTOCD-DZ), were applied at the Hartree-Fock level to determine electric quadrupole polarizabilities of nuclear magnetic shielding for molecules in the presence of a nonuniform electric field with a uniform gradient. The quadrupole polarizabilities depend on the origin of the coordinate system, but values of the magnetic field induced at a reference nucleus, determined via the CTOCD-DZ approach, are origin independent for any calculations relying on the algebraic approximation, irrespective of size and quality of the (gaugeless) basis set employed. On the other hand, theoretical estimates of the induced magnetic field obtained by single-origin methods are translationally invariant only in the limit of complete basis sets. Calculations of electric quadrupole polarizabilities of nuclear magnetic shielding are reported for H2, HF, H2O, NH3, and CH4 molecules.

  3. Enhanced affinity of ketotifen toward tamarind seed polysaccharide in comparison with hydroxyethylcellulose and hyaluronic acid: a nuclear magnetic resonance investigation.

    PubMed

    Uccello-Barretta, Gloria; Nazzi, Samuele; Balzano, Federica; Di Colo, Giacomo; Zambito, Ylenia; Zaino, Chiara; Sansò, Marco; Salvadori, Eleonora; Benvenuti, Marco

    2008-08-01

    Nuclear magnetic resonance (NMR) spectroscopy demonstrated that, in aqueous solution, ketotifen fumarate bound more strongly to tamarind seed polysaccharide (TSP) than to hydroxyethylcellulose or hyaluronic acid. Results were confirmed by dynamic dialysis technique. PMID:18595715

  4. Two Phase Flow Measurements by Nuclear Magnetic Resonance (NMR)

    SciTech Connect

    Altobelli, Stephen A; Fukushima, Eiichi

    2006-08-14

    different nuclei, protons and 19F. It also uses two different types of NMR image formation, a conventional spin-echo and a single-point method. The single-point method is notable for being useful for imaging materials which are much more rigid than can usually be studied by NMR imaging. We use it to image “low density” polyethylene (LDPE) plastic in this application. We have reduced the imaging time for this three-phase imaging method to less than 10 s per pair of profiles by using new hardware. Directly measuring the solid LDPE signal was a novel feature for multi-phase flow studies. We also used thermally polarized gas NMR (as opposed to hyper-polarized gas) which produces low signal to noise ratios because gas densities are on the order of 1000 times smaller than liquid densities. However since we used multi-atom molecules that have short T1's and operated at elevated pressures we could overcome some of the losses. Thermally polarized gases have advantages over hyperpolarized gases in the ease of preparation, and in maintaining a well-defined polarization. In these studies (Codd and Altobelli, 2003), we used stimulated echo sequences to successfully obtain propagators of gas in bead packs out to observation times of 300 ms. Zarraga, et al. (2000) used laser-sheet profilometry to investigate normal stress differences in concentrated suspensions. Recently we developed an NMR imaging analog for comparison with numerical work that is being performed by Rekha Rao at Sandia National Laboratories (Rao, Mondy, Sun, et al, 2002). A neutrally buoyant suspension of 100 mm PMMA spheres in a Newtonian liquid was sheared in a vertical Couette apparatus inside the magnet. The outer cylinder rotates and the inner cylinder is fixed. At these low rotation rates, the free-surface of the Newtonian liquid shows no measurable deformation, but the suspension clearly shows its non-Newtonian character.

  5. Nuclear Spin Polarization of Phosphorus Donors in Silicon. Direct Evidence from 31P-Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Gumann, Patryk; Ramanathan, Chandrasekhar; Patange, Om; Moussa, Osama; Thewalt, Mike; Riemann, Helge; Abrosimov, Nikolay; Becker, Peter; Pohl, Hans-Joachim; Itoh, Kohei; Cory, David G.

    2014-03-01

    We experimentally demonstrate the optical hyperpolarization and coherent control of 31P, nuclear spins in single crystal silicon via the inductive readout of the nuclear magnetic resonance (NMR) signal of 31P at a concentration of 1.5 x 1015 cc-1. The obtained polarization is sufficient the 31P spin polarization of 1.17 x 1015 in a 10 mm x 10 mm sample, observed in one FID with signal-to-noise ration of 113. The linewidth is 800 Hz. The Hahn echo pulse sequence reveals a 31P T2 time of 0.42 s at 1.6 K, which was extended by the Carr Purcell cycle to 1.2 s at the same temperature. The maximum build-up of the nuclear polarization was achieved within ~577 seconds, at 4.2 K, in 6.7 T, using optical excitations provided by an infra-red laser. This work has been supported by CERC Canada.

  6. 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. PMID:24093546

  7. Proton-Enhanced 13C Nuclear Magnetic Resonance of Lipids and Biomembranes

    PubMed Central

    Urbina, Julio; Waugh, J. S.

    1974-01-01

    A recently developed nuclear double resonance technique which permits sensitive detection, together with high resolution, of rare spins in solids or other dipolar-coupled nuclear systems [Pines, Gibby, and Waugh (1973) J. Chem. Phys. 59, 569] has been applied to the study of natural abundance 13C-nuclear magnetic resonance in lipid mesophases and of selectively labeled carbon sites in bacterial membranes. Detailed microscopic information on the molecular organization and phase transitions of the lipid phases and their interaction with ions and other molecules can be obtained from the study of the chemical shift anisotropies and dynamical aspects of the 13C NMR spectra of unsonicated lipid dispersions (liposomes). Experiments are reported which demonstrated the feasibility of quantitatively observing the 13C-nuclear magnetic resonance of specifically labeled sites in unperturbed Escherichia coli membrane vesicles for the study of the physical state of the lipids with the aim of relating it to the known lipid-dependent functional properties of the membranes. PMID:4531036

  8. Nuclear magnetic resonance of external protons using continuous dynamical decoupling with shallow NV centers

    NASA Astrophysics Data System (ADS)

    de Las Casas, Charles; Ohno, Kenichi; Awschalom, David D.

    2015-03-01

    The nitrogen vacancy (NV) center in diamond is a paramagnetic defect with excellent spin properties that can reside within a few nanometers of the diamond surface, enabling atomic-scale magnetic resonance sensing of external nuclear spins. Here we use rotating frame longitudinal spin relaxation (T1ρ) based sensing schemes, known as Continuous Dynamical Decoupling (CDD), to detect external nuclear spins with shallow NV centers (<5 nm from the surface). Distinguishing neighboring nuclear spins from each other requires the NV center be near enough to create differences in the hyperfine shifts and coupling strengths of the nuclei. However, spin coherence time and consequently the sensitivity of dynamical decoupling techniques degrade sharply as NVs become shallower. We use strong continuous driving to overcome this fast decoherence and detect an ensemble of external nuclear spins using a single shallow NV center with a short T2 (<2 μs) at magnetic fields as high as 0.5 Tesla. The increased sensitivity of this method relative to pulsed dynamical decoupling techniques demonstrates the benefits of CDD for sensing with very shallow NV centers. This work was supported by DARPA, AFOSR, and the DIAMANT program.

  9. Using magnetic moments to study the nuclear structure of I{>=} 2 states

    SciTech Connect

    Torres, D. A.

    2013-05-06

    The experimental study of magnetic moments for nuclear states near the ground state, I{>=} 2, provides a powerful tool to test nuclear structure models. Traditionally, the use of Coulomb excitation reactions have been utilized to study low spin states, mostly I= 2. The use of alternative reaction channels, such as {alpha} transfer, for the production of radioactive species that, otherwise, will be only produced in future radioactive beam facilities has proved to be an alternative to measure not only excited states with I > 2, but to populate and study long-live radioactive nuclei. This contribution will present the experimental tools and challenges for the use of the transient field technique for the measurement of g factors in nuclear states with I{>=} 2, using Coulomb excitation and {alpha}-transfer reactions. Recent examples of experimental results near the N= 50 shell closure, and the experimental challenges for future implementations with radioactive beams, will be discussed.

  10. Infrared spectroscopy of 17O- and 18O-enriched carbon dioxide: Line positions and intensities in the 4681-5337 cm-1 region

    NASA Astrophysics Data System (ADS)

    Borkov, Yu. G.; Jacquemart, D.; Lyulin, O. M.; Tashkun, S. A.; Perevalov, V. I.

    2015-07-01

    The line positions and intensities of carbon dioxide isotopologues have been retrieved in the 4681-5337 cm-1 spectral range from Fourier transform spectra of carbon dioxide recorded in LADIR (Paris, France) with the Bruker IFS 125-HR [Jacquemart D, et al., J Quant Spectrosc Radiat Transf 2012;113:961-975]. In total 6386 line positions and intensities of 89 bands of 12 isotopologues 16O12C16O, 16O13C16O, 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 18O12C18O, 17O12C18O, 17O12C17O, 18O13C18O, 17O13C18O, and 17O13C17O have been retrieved. 23 bands were newly assigned. All studied bands belong to the ΔP=7 series of transitions, where P = 2V1 +V2 + 3V3 is the polyad number (Vi are vibrational quantum numbers). The accuracy of the line position measurement is about 0.3×10-3 cm-1 for the unblended and not very weak lines. The accuracy of the line intensities varies from 4% to 15% depending on the isotopologue, on the intensity of the line and on the extent of the line overlapping. The observed intensities were used to fit the effective dipole moment parameters for the ΔP=7 series of transitions in 16O12C18O, 16O12C17O, 12C17O2, 17O12C18O, 16O13C17O, 13C17O2 and 17O13C18O isotopologues of carbon dioxide.

  11. [Recent progress in nuclear magnetic resonance spectrum for drug research and development].

    PubMed

    Zhong, Jun; Jiang, Xue-mei

    2015-01-01

    In the process of modern drug research, the new methods and technologies which can detect drug molecules' chemical composition, structure and interaction with biomolecules are always the key scientific problems people care about. Spectra (including IR, UV and NMR) are the most common analytical methods, of which NMR can obtain detailed parameter about the nucleus of organic molecules through researching the laws of nuclear transition in the impact of surrounding chemical environment. The parameter contains rich information about the chemical composition, structure and interaction with other molecules of organic molecules. In many complex environments, such as liquid, solid or gas state, even biological in situ environment, NMR can provide molecules' chemical composition, atomic-resolution three-dimensional structure, information of interaction with each other and dynamic process, especially the information about drug interacting with biomacromolecules. In recent years, the applications of nuclear magnetic resonance spectrum in drug research and development are more and more widespread. This paper reviewed its recent progress in structure and dynamic of targeted biological macromolecules, drug design and screening and drug metabolism in drug research and development. In the first part, we gave a brief introduction of nuclear magnetic resonance technology and its applications in drug research. In the second part, we explained the basic principles briefly and summarized progress in methods and techniques for drug research. In the third part, we discussed applications of nuclear magnetic resonance ir structure and dynamic of targeted biological macromolecules, drug design and screening and drug metabolism in detail. The conclusions were stated in the last part. PMID:25993865

  12. Small-scale instrumentation for nuclear magnetic resonance of porous media

    NASA Astrophysics Data System (ADS)

    Blümich, Bernhard; Casanova, Federico; Dabrowski, Martin; Danieli, Ernesto; Evertz, Loribeth; Haber, Agnes; Van Landeghem, Maxime; Haber-Pohlmeier, Sabina; Olaru, Alexandra; Perlo, Juan; Sucre, Oscar

    2011-01-01

    The investigation of fluids confined to porous media is the oldest topic of investigation with small-scale nuclear magnetic resonance (NMR) instruments, as such instruments are mobile and can be moved to the site of the object, such as the borehole of an oil well. While the analysis was originally restricted by the inferior homogeneity of the employed magnets to relaxation measurements, today, portable magnets are available for all types of NMR measurements concerning relaxometry, imaging and spectroscopy in two types of geometries. These geometries refer to closed magnets that surround the sample and open magnets, which are brought close to the object for measurement. The current state of the art of portable, small-scale NMR instruments is reviewed and recent applications of such instruments are featured. These include the porosity analysis and description of diesel particulate filters, the determination of the moisture content in walls from gray concrete, new approaches to analyze the pore space and moisture migration in soil, and the constitutional analysis of the mortar base of ancient wall paintings.

  13. Nanomagnetism of Core-Shell Magnetic Nanoparticles and Application in Spent Nuclear Fuel Separation

    NASA Astrophysics Data System (ADS)

    Tarsem Singh, Maninder Kaur

    This dissertation presents the study on novel core-shell magnetic nanoparticles (NPs) with unique magnetic properties. Understanding the fundamental physics of antiferromagnetic - ferromagnetic interactions is essential to apply in different applications. Chromium (Cr) doped and undoped core-shell iron/iron-oxide NPs have been synthesized using cluster deposition system and studied with respect to their nanostructures, morphologies, sizes, chemical composition and magnetic properties. The room-temperature magnetic properties of Fe based NPs shows the strong dependence of intra/inter-particle interaction on NP size. The Cr-doped Fe NP shows the origin of sigma-FeCr phase at very low Cr concentration (2 at.%) unlike others reported at high Cr content and interaction reversal from dipolar to exchange interaction. A theoretical model of watermelon is constructed based on the experimental results and core-shell NP system in order to explain the physics of exchange interaction in Cr-doped Fe particles. The magnetic nanoparticle---chelator separation nanotechnology is investigated for spent nuclear fuel recycling and is reported 97% and 80% of extraction for Am(III) and Pu(IV) actinides respectively. If the long-term heat generating actinides such as Am(III) can be efficiently removed from the used fuel raffinates, the volume of material that can be placed in a given amount of repository space can be significantly increased. As it is a simple, versatile, compact, and cost efficient process that minimizes secondary waste and improves storage performance.

  14. Rapid measurements of heterogeneity in sandstones using low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mitchell, Jonathan

    2014-03-01

    Sandstone rocks can contain microscopic variations in composition that complicate interpretation of nuclear magnetic resonance (NMR) relaxation time measurements. In this work, methods for assessing the degree of sample heterogeneity are demonstrated in three sandstones. A two-dimensional T1-Δχapp correlation (where Δχapp is the apparent solid/liquid magnetic susceptibility contrast) reveals the microscopic heterogeneity in composition, whilst a spatially resolved T1 profile reveals the macroscopic structural heterogeneity. To perform these measurements efficiently, a rapid measure of longitudinal T1 relaxation time has been implemented on a low-field NMR spectrometer with a magnetic field strength B0=0.3 T. The “double-shot” T1 pulse sequence is appropriate for analysis of porous materials in general. Example relaxation time distributions are presented for doped water phantoms to validate the method. The acquisition time of the double-shot T1 sequence is equivalent to the single-shot Carr-Purcell Meiboom-Gill (CPMG) sequence used routinely in petrophysics to measure transverse T2 relaxation. Rapid T1 measurements enable practical studies of core plugs at magnetic field strengths previously considered inappropriate, as T1 is independent of molecular diffusion through pore-scale (internal) magnetic field gradients.

  15. Partial-Homogeneity-Based Two-Dimensional High-Resolution Nuclear Magnetic Resonance Spectroscopy under Inhomogeneous Magnetic Fields.

    PubMed

    Qiu, Wenqi; Wei, Zhiliang; Ding, Nan; Yang, Yu; Ye, Qimiao; Lin, Yulan; Chen, Zhong

    2016-05-18

    High-resolution multidimensional nuclear magnetic resonance (NMR) spectroscopy serves as an irreplaceable and versatile tool in various chemical investigations. In this study, a method based on the concept of partial homogeneity is developed to offer two-dimensional (2D) high-resolution NMR spectra under inhomogeneous fields. Oscillating gradients are exerted to encode the high-resolution information, and a field-inhomogeneity correction algorithm based on pattern recognition is designed to recover high-resolution spectra. Under fields where inhomogeneity primarily distributes along a single orientation, the proposed method will improve performances of 2D NMR spectroscopy without increasing the experimental duration or significant loss in sensitivity, and thus may open important perspectives for studies of inhomogeneous chemical systems. PMID:26891886

  16. Pygmy dipole resonance in 140Ce via inelastic scattering of 17O

    NASA Astrophysics Data System (ADS)

    Krzysiek, M.; Kmiecik, M.; Maj, A.; Bednarczyk, P.; Bracco, A.; Crespi, F. C. L.; Lanza, E. G.; Litvinova, E.; Paar, N.; Avigo, R.; Bazzacco, D.; Benzoni, G.; Birkenbach, B.; Blasi, N.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Ciemała, M.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Giaz, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hess, H.; Isocarte, R.; Jungclaus, A.; Leoni, S.; Ljungvall, J.; Lunardi, S.; Mazurek, K.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Milion, B.; Morales, A. I.; Napoli, D. R.; Nicolini, R.; Pellegri, L.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Salsac, M. D.; Siebeck, B.; Siem, S.; Söderström, P.-A.; Ur, C.; Valiente-Dobon, J. J.; Wieland, O.; Ziebliński, M.

    2016-04-01

    The γ decay from the high-lying states of 140Ce excited via inelastic scattering of 17O at a bombarding energy of 340 MeV was measured using the high-resolution AGATA-demonstrator array in coincidence with scattered ions detected in two segmented Δ E -E silicon detectors. Angular distributions of scattered ions and emitted γ rays were measured, as well as their differential cross sections. The excitation of 1- states below the neutron separation energy is similar to the one obtained in reactions with the α isoscalar probe. The comparison between the experimental differential cross sections and the corresponding predictions using the distorted-wave Born approximation allowed us to extract the isoscalar component of identified 1- pygmy states. For this analysis the form factor obtained by folding microscopically calculated transition densities and optical potentials was used.

  17. Optimised conditions for the synthesis of (17)O and (18)O labelled cholesterol.

    PubMed

    de la Calle Arregui, Celia; Purdie, Jonathan A; Haslam, Catherine A; Law, Robert V; Sanderson, John M

    2016-02-01

    Conditions are described for the preparation of cholesterol with (17)O and (18)O labels from i-cholesteryl methyl ether using minimal amounts of isotopically enriched water. Optimum yields employed trifluoromethanesulfonic acid as catalyst in 1,4-dioxane at room temperature with 5 equivalents of water. An isotopic enrichment >90% of that of the water used for the reaction could be attained. Tetrafluoroboric acid could also be used as catalyst, at the expense of a lower overall reaction yield. Byproducts from the reaction included dicholesteryl ether, methyl cholesteryl ether, compounds formed by ether hydrolysis, and olefins arising from elimination reactions. Reactions in tetrahydrofuran yielded significant amounts of cholesteryl ethers formed by reaction with alcohols arising from hydrolysis of the solvent. PMID:26724708

  18. Rapid Synthesis of Thin and Long Mo17O47 Nanowire-Arrays in an Oxygen Deficient Flame.

    PubMed

    Allen, Patrick; Cai, Lili; Zhou, Lite; Zhao, Chenqi; Rao, Pratap M

    2016-01-01

    Mo17O47 nanowire-arrays are promising active materials and electrically-conductive supports for batteries and other devices. While high surface area resulting from long, thin, densely packed nanowires generally leads to improved performance in a wide variety of applications, the Mo17O47 nanowire-arrays synthesized previously by electrically-heated chemical vapor deposition under vacuum conditions were relatively thick and short. Here, we demonstrate a method to grow significantly thinner and longer, densely packed, high-purity Mo17O47 nanowire-arrays with diameters of 20-60 nm and lengths of 4-6 μm on metal foil substrates using rapid atmospheric flame vapor deposition without any chamber or walls. The atmospheric pressure and 1000 °C evaporation temperature resulted in smaller diameters, longer lengths and order-of-magnitude faster growth rate than previously demonstrated. As explained by kinetic and thermodynamic calculations, the selective synthesis of high-purity Mo17O47 nanowires is achieved due to low oxygen partial pressure in the flame products as a result of the high ratio of fuel to oxidizer supplied to the flame, which enables the correct ratio of MoO2 and MoO3 vapor concentrations for the growth of Mo17O47. This flame synthesis method is therefore a promising route for the growth of composition-controlled one-dimensional metal oxide nanomaterials for many applications. PMID:27271194

  19. Rapid Synthesis of Thin and Long Mo17O47 Nanowire-Arrays in an Oxygen Deficient Flame

    PubMed Central

    Allen, Patrick; Cai, Lili; Zhou, Lite; Zhao, Chenqi; Rao, Pratap M.

    2016-01-01

    Mo17O47 nanowire-arrays are promising active materials and electrically-conductive supports for batteries and other devices. While high surface area resulting from long, thin, densely packed nanowires generally leads to improved performance in a wide variety of applications, the Mo17O47 nanowire-arrays synthesized previously by electrically-heated chemical vapor deposition under vacuum conditions were relatively thick and short. Here, we demonstrate a method to grow significantly thinner and longer, densely packed, high-purity Mo17O47 nanowire-arrays with diameters of 20–60 nm and lengths of 4–6 μm on metal foil substrates using rapid atmospheric flame vapor deposition without any chamber or walls. The atmospheric pressure and 1000 °C evaporation temperature resulted in smaller diameters, longer lengths and order-of-magnitude faster growth rate than previously demonstrated. As explained by kinetic and thermodynamic calculations, the selective synthesis of high-purity Mo17O47 nanowires is achieved due to low oxygen partial pressure in the flame products as a result of the high ratio of fuel to oxidizer supplied to the flame, which enables the correct ratio of MoO2 and MoO3 vapor concentrations for the growth of Mo17O47. This flame synthesis method is therefore a promising route for the growth of composition-controlled one-dimensional metal oxide nanomaterials for many applications. PMID:27271194

  20. Rapid Synthesis of Thin and Long Mo17O47 Nanowire-Arrays in an Oxygen Deficient Flame

    NASA Astrophysics Data System (ADS)

    Allen, Patrick; Cai, Lili; Zhou, Lite; Zhao, Chenqi; Rao, Pratap M.

    2016-06-01

    Mo17O47 nanowire-arrays are promising active materials and electrically-conductive supports for batteries and other devices. While high surface area resulting from long, thin, densely packed nanowires generally leads to improved performance in a wide variety of applications, the Mo17O47 nanowire-arrays synthesized previously by electrically-heated chemical vapor deposition under vacuum conditions were relatively thick and short. Here, we demonstrate a method to grow significantly thinner and longer, densely packed, high-purity Mo17O47 nanowire-arrays with diameters of 20–60 nm and lengths of 4–6 μm on metal foil substrates using rapid atmospheric flame vapor deposition without any chamber or walls. The atmospheric pressure and 1000 °C evaporation temperature resulted in smaller diameters, longer lengths and order-of-magnitude faster growth rate than previously demonstrated. As explained by kinetic and thermodynamic calculations, the selective synthesis of high-purity Mo17O47 nanowires is achieved due to low oxygen partial pressure in the flame products as a result of the high ratio of fuel to oxidizer supplied to the flame, which enables the correct ratio of MoO2 and MoO3 vapor concentrations for the growth of Mo17O47. This flame synthesis method is therefore a promising route for the growth of composition-controlled one-dimensional metal oxide nanomaterials for many applications.

  1. 17O-excess traces atmospheric nitrate in paleo groundwater of the Saharan desert

    NASA Astrophysics Data System (ADS)

    Dietzel, M.; Leis, A.; Abdalla, R.; Savarino, J.; Morin, S.; Böttcher, M. E.; Köhler, S.

    2013-12-01

    Saharan paleo groundwater from the Hasouna area of Libya contains up to 1.8 mM of nitrate, the origin of which is still disputed. Herein we show that a positive 17O-excess in NO3- (Δ17ONO3 = δ17ONO3 - 0.52 δ18ONO3) is preserved in the paleo groundwater. The 17O-excess provides an excellent tracer of atmospheric NO3-, which is caused by the interaction of ozone with NOx via photochemical reactions, coupled with a non-mass dependent isotope fractionation. Our Δ17ONO3 data from 0.4 to 5.0‰ (n = 28) indicate that up to x [NO3-]atm = 20 mol % of total dissolved NO3- originated from the Earth's atmosphere. High Δ17ONO3 values correspond to soils that are barren in dry periods, while low Δ17ONO3 values correspond to more fertile soils. Coupled high Δ17ONO3 and high x [NO3-]atm values are caused by a sudden wash out of dry deposition of atmospheric NO3- on plant or soil surfaces within humid-wet cycles. The individual isotope and chemical composition of the Hasouna groundwater can be followed by a binary mixing approach using the lowest and highest mineralized groundwater as end-members without considering evaporation. Using the δ34SSO4 and δ18OSO4 isotope signature of dissolved sulfate, no indication is found for a superimposition by denitrification, e.g. involving pyrite minerals within the aquifers. It is suggested that dissolved sulfate originates from the dissolution of calcium sulfate minerals during groundwater evolution.

  2. 17O excess traces atmospheric nitrate in paleo-groundwater of the Saharan desert

    NASA Astrophysics Data System (ADS)

    Dietzel, M.; Leis, A.; Abdalla, R.; Savarino, J.; Morin, S.; Böttcher, M. E.; Köhler, S.

    2014-06-01

    Saharan paleo-groundwater from the Hasouna area of Libya contains up to 1.8 mM of nitrate, which exceeds the World Health Organization limit for drinking water, but the origin is still disputed. Herein we show that a positive 17O excess in NO3- (Δ17ONO3 = Δ17ONO3 - 0.52 δ18ONO3) is preserved in the paleo-groundwater. The 17O excess provides an excellent tracer of atmospheric NO3-, which is caused by the interaction of ozone with NOx via photochemical reactions, coupled with a non-mass-dependent isotope fractionation. Our Δ17ONO3 data from 0.4 to 5.0 ‰ (n = 28) indicate that up to 20 mol % of total dissolved NO3- originated from the Earth's atmosphere (x[NO3-]atm), where the remaining NO3- refers to microbially induced nitrification in soils. High Δ17ONO3 values correspond to soils that are barren in dry periods, while low Δ17ONO3 values correspond to more fertile soils. Coupled high Δ17ONO3 and high x[NO3-]atm values are caused by a sudden wash-out of accumulated disposition of atmospheric NO3- on plants, soil surfaces and in vadose zones within humid-wet cycles. The individual isotope and chemical composition of the Hasouna groundwater can be followed by a binary mixing approach using the lowest and highest mineralised groundwater as end members without considering evaporation. Using the δ34SSO4 and δ18OSO4 isotope signature of dissolved SO42-, no indication is found for a superimposition by denitrification, e.g. involving pyrite minerals within the aquifers. It is suggested that dissolved SO42- originates from the dissolution of CaSO4 minerals during groundwater evolution.

  3. Tunnel-diode resonator and nuclear magnetic resonance studies of low-dimensional magnetic and superconducting systems

    NASA Astrophysics Data System (ADS)

    Yeninas, Steven Lee

    This thesis emphasizes two frequency-domain techniques which uniquely employ radio frequency (RF) excitations to investigate the static and dynamic properties of novel magnetic and superconducting materials. The first technique is a tunnel-diode resonator (TDR) which detects bulk changes in the dynamic susceptibility, chi = dM/dH. The capability of TDR to operate at low temperatures (less than 100 mK) and high fields (up to 65 T in pulsed fields) was critical for investigations of the antiferromagnetically correlated magnetic molecules Cr12Cu2 and Cr12 Ln4 (Ln = Y, Eu, Gd, Tb, Dy, Ho, Er, Yb), and the superconductor SrFe2(As1--xPx) 2 (x = 0.35). Investigations of Cr12Cu 2 and Cr12Ln4 demonstrates the first implementation of TDR to experimentally investigate the lowlying energy spectra of magnetic molecules in pulsed magnetic fields. Zeeman splitting of the quantum spin states results in transitions between field-dependent ground state energy levels observed as peaks in dM/dH at 600 mK, and demonstrate good agreement with theoretical calculations using a isotropic Heisenberg spin Hamiltonian. Increasing temperature to 2.5 K, TDR reveals a rich spectrum of frequency-dependent level crossings from thermally populated excited states which cannot be observed by conventional static magnetometry techniques. The last study presented uses TDR in pulsed fields to determine the temperature-dependent upper-critical field Hc2 to investigate the effects of columnar defects arising from heavy ion irradiation of SrFe2(As 1--xPx)2. Results suggest irradiation uniformly suppresses Tc and Hc2, and does not introduce additional features on H c2(T) and the shapes of the anisotropic Hc2 curves indicates a nodal superconducting gap. The second technique is nuclear magnetic resonance (NMR) which yields site specific magnetic and electronic information arising from hyperfine interactions for select magnetic nuclei. NMR spectra and nuclear spin-lattice relaxation measurements are reported

  4. Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

    SciTech Connect

    Urban, Jeffry Todd

    2004-12-21

    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. 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

  5. Theory of damped quantum rotation in nuclear magnetic resonance spectra. III. Nuclear permutation symmetry of the line shape equation.

    PubMed

    Szymański, S

    2009-12-28

    The damped quantum rotation (DQR) theory describes manifestations in nuclear magnetic resonance spectra of the coherent and stochastic dynamics of N-fold molecular rotors composed of indistinguishable particles. The standard jump model is only a limiting case of the DQR approach; outside this limit, the stochastic motions of such rotors have no kinematic description. In this paper, completing the previous two of this series, consequences of nuclear permutation symmetry for the properties of the DQR line shape equation are considered. The systems addressed are planar rotors, such as aromatic hydrocarbons' rings, occurring inside of molecular crystals oriented in the magnetic field. Under such conditions, oddfold rotors can have nontrivial permutation symmetries only for peculiar orientations while evenfold ones always retain their intrinsic symmetry element, which is rotation by 180 degrees about the N-fold axis; in specific orientations the latter can gain two additional symmetry elements. It is shown that the symmetry selection rules applicable to the classical rate processes in fluids, once recognized as having two diverse aspects, macroscopic and microscopic, are also rigorously valid for the DQR processes in the solid state. However, formal justification of these rules is different because the DQR equation is based on the Pauli principle, which is ignored in the jump model. For objects like the benzene ring, exploitation of these rules in simulations of spectra using the DQR equation can be of critical significance for the feasibility of the calculations. Examples of such calculations for the proton system of the benzene ring in a general orientation are provided. It is also shown that, because of the intrinsic symmetries of the evenfold rotors, many of the DQR processes, which such rotors can undergo, are unobservable in NMR spectra. PMID:20059076

  6. Measurement of the true transverse nuclear magnetic resonance relaxation in the presence of field gradients

    NASA Astrophysics Data System (ADS)

    Mitchell, J.; Chandrasekera, T. C.; Gladden, L. F.

    2013-08-01

    A measure of the nuclear spin transverse relaxation time T2, as determined using the nuclear magnetic resonance Carr-Purcell Meiboom-Gill (CPMG) experiment, provides unique information characterizing the microstructure of porous media which are themselves ubiquitous across fields of petrophysics, biophysics, and chemical engineering. However, the CPMG measurement is sensitive to diffusion in large magnetic field gradients. Under such conditions an effective relaxation time T_{2,eff} is observed instead, described by a combination of relaxation and diffusion exponents. The relaxation exponent always varies as nte (where n is the number, and te is the temporal separation, of spin echoes). The diffusion exponent varies as nt_e^k, where 1 < k ⩽ 3, although the exact analytic form is often unknown. Here we present a general approach to separating the influence of relaxation and diffusion by utilizing a composite diffusion exponent. Any T_{2,eff} component with a power of k > 1 is removed to provide a measure of the true T2 relaxation time distribution from CPMG data acquired in the presence of a strong background gradient. We apply the technique to discriminate between the effects of relaxation and diffusion in porous media using catalysts and rocks as examples. The method is generally applicable to any CPMG measurements conducted in the presence of a static magnetic field gradient.

  7. High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

    SciTech Connect

    Lin, Tingting; Zhao, Jing; Zhang, Yi; Krause, Hans-Joachim; Lee, Yong-Ho; Lin, Jun

    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 2 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.

  8. Nuclear magnetic resonance inverse spectra of InGaAs quantum dots: Atomistic level structural information

    NASA Astrophysics Data System (ADS)

    Bulutay, Ceyhun; Chekhovich, E. A.; Tartakovskii, A. I.

    2014-11-01

    A wealth of atomistic information is contained within a self-assembled quantum dot (QD), associated with its chemical composition and the growth history. In the presence of quadrupolar nuclei, as in InGaAs QDs, much of this is inherited to nuclear spins via the coupling between the strain within the polar lattice and the electric quadrupole moments of the nuclei. Here, we present a computational study of the recently introduced inverse spectra nuclear magnetic resonance technique to assess its suitability for extracting such structural information. We observe marked spectral differences between the compound InAs and alloy InGaAs QDs. These are linked to the local biaxial and shear strains, and the local bonding configurations. The cation alloying plays a crucial role especially for the arsenic nuclei. The isotopic line profiles also largely differ among nuclear species: While the central transition of the gallium isotopes have a narrow linewidth, those of arsenic and indium are much broader and oppositely skewed with respect to each other. The statistical distributions of electric field gradient (EFG) parameters of the nuclei within the QD are analyzed. The consequences of various EFG axial orientation characteristics are discussed. Finally, the possibility of suppressing the first-order quadrupolar shifts is demonstrated by simply tilting the sample with respect to the static magnetic field.

  9. Probing the effective nuclear-spin magnetic field in a single quantum dot via full counting statistics

    SciTech Connect

    Xue, Hai-Bin; Nie, Yi-Hang; Chen, Jingzhe; Ren, Wei

    2015-03-15

    We study theoretically the full counting statistics of electron transport through a quantum dot weakly coupled to two ferromagnetic leads, in which an effective nuclear-spin magnetic field originating from the configuration of nuclear spins is considered. We demonstrate that the quantum coherence between the two singly-occupied eigenstates and the spin polarization of two ferromagnetic leads play an important role in the formation of super-Poissonian noise. In particular, the orientation and magnitude of the effective field have a significant influence on the variations of the values of high-order cumulants, and the variations of the skewness and kurtosis values are more sensitive to the orientation and magnitude of the effective field than the shot noise. Thus, the high-order cumulants of transport current can be used to qualitatively extract information on the orientation and magnitude of the effective nuclear-spin magnetic field in a single quantum dot. - Highlights: • The effective nuclear-spin magnetic field gives rise to the off-diagonal elements of the reduced density matrix of single QD. • The off-diagonal elements of reduced density matrix of the QD have a significant impact on the high-order current cumulants. • The high-order current cumulants are sensitive to the orientation and magnitude of the effective nuclear-spin magnetic field. • The FCS can be used to detect the orientation and magnitude of the effective nuclear-spin magnetic field in a single QD.

  10. Prospects for Sub-Micron Solid State Nuclear Magnetic Resonance Imaging with Low-Temperature Dynamic Nuclear Polarization

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2010-01-01

    Summary We evaluate the feasibility of 1H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol/water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 µl sample yields a 1H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that 1H NMR signals from 1 µm3 voxel volumes should be readily detectable, and voxels as small as 0.03 µm3 may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz 1H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension. PMID:20458431

  11. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K

    NASA Astrophysics Data System (ADS)

    Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20-25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids.

  12. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K

    PubMed Central

    Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2012-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20–25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier (Thurber et al., J. Magn. Reson. 2008) [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids. PMID:23238592

  13. Solid-state nitrogen-14 nuclear magnetic resonance enhanced by dynamic nuclear polarization using a gyrotron.

    PubMed

    Vitzthum, Veronika; Caporini, Marc A; Bodenhausen, Geoffrey

    2010-07-01

    By combining indirect detection of 14N with dynamic nuclear polarization (DNP) using a gyrotron, the signal-to-noise ratio can be dramatically improved and the recovery delay between subsequent experiments can be shortened. Spectra of glassy samples of the amino acid proline doped with the stable bi-radical TOTAPOL rotating at 15.625 kHz at 110K were obtained in a 400 MHz solid-state NMR spectrometer equipped with a gyrotron for microwave irradiation at 263 GHz. DNP enhancement factors on the order of epsilon approximately 40 were achieved. The recovery delays can be reduced from 60 s without radicals at 300 K to 6 s with radicals at 110 K. In the absence of radicals at room temperature, the proton relaxation in proline is inefficient due to the absence of rotating methyl groups and other heat sinks, thus making long recovery delays mandatory. DNP allows one to reduce the acquisition times of 13C-detected 14N spectra from several days to a few hours. PMID:20488737

  14. Nuclear magnetic resonance study of the bonding and diffusion of CO chemisorbed on Pd

    SciTech Connect

    Shore, S.E.; Ansermet, J.; Slichter, C.P.; Sinfelt, J.H.

    1987-03-02

    The authors report use of /sup 17/O and /sup 13/C NMR to study the bonding of CO on Pd particles. By /sup 17/O-/sup 13/C double resonance, they measure the CO bond length to be 1.20 +- 0.03 A. The /sup 13/C resonance frequency is exceptionally high, 310 ppm above values typical for metal carbonyls. Evidence that the shift arises from electron-spin polarization is given from studies of the magnitude and the dependence on temperature and frequency of the /sup 13/C spin-lattice relaxation time. A diffusion enegy of 6 +- 2 kcal/mole, half that of CO on Pt, is deduced from motional narrowing of the /sup 13/C NMR line.

  15. The use and promise of nuclear magnetic resonance imaging in epilepsy.

    PubMed

    Oldendorf, W H

    1984-01-01

    The revolutionary influence of X-ray computerized tomography (CT) on neurodiagnosis will be considerably extended by a newer imaging probe using magnetic fields. This form of imaging uses nuclear magnetic resonance (NMR) as the probe-tissue interaction to make many regional measurements of tissue in a short time, thus allowing an image to be computer-reconstructed. The nuclei of about 100 nuclides have significant magnetic properties, behaving like small permanent bar magnets. The most interesting of these in brain tissue are ordinary hydrogen, sodium, and phosphorus. Placed in a strong magnetic field, they partially align themselves with the field. They can then absorb energy which will subsequently be reradiated. Since the resonant frequency of each nucleus is proportional to the magnetic field in which it finds itself, producing fields which change predictably in strength with position, it becomes possible to localize the activated nuclei. Images of hydrogen density and relaxation times can be made and offer considerable tissue characterization. Bone is nearly invisible and considerable gray-white matter contrast is seen. Factors altering water-binding in tissues affect the image. Malignant tissue usually is seen in contrast to adjacent healthy tissue. Movement of blood is visible. By measuring energy-rich phosphorus, energy stores can be determined. There is no tissue ionization, no injected contrast materials are needed, and there are no radioactive materials involved. NMR scanners probably will replace CT within the next decade for most brain scanning purposes and will offer considerably greater tissue characterization which surely will influence studies of human epilepsy. PMID:6745224

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

    SciTech Connect

    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 locked 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.}

  17. VizieR Online Data Catalog: C18O/C17O ratios in the Galactic center

    NASA Astrophysics Data System (ADS)

    Zhang, J. S.; Sun, L. L.; Riquelme, D.; Henkel, C.; Lu, D. R.; Zhang, Y.; Wang, J. Z.; Wang, M.; Li, J.

    2015-09-01

    Our mapping observations of the J=1-0 lines of 12CO, 13 and C17O were carried out with the DLH 13.7m telescope of the Purple Mountain Observatory (PMO) at Delingha in 2011 January and 2012 May and November. The C18O and C17O lines were also observed in single-point mode toward Sgr B2 with the IRAM 30m telescope in 2011 September, and toward Sgr C and Sgr D with the Mopra 22m in 2014 June. (2 data files).

  18. Correlations between 29Si, 17O and 1H NMR properties and local structures in silicates: an ab initio calculation

    NASA Astrophysics Data System (ADS)

    Xue, X.; Kanzaki, M.

    In order to gain insight into the correlations between 29Si, 17O and 1H NMR properties (chemical shift and quadrupolar coupling parameters) and local structures in silicates, ab initio self-consistent field Hartree-Fock molecular orbital calculations have been carried out on silicate clusters of various polymerizations and intertetrahedral (Si-O-Si) angles. These include Si(OH)4 monomers (isolated as well as interacting), Si2O(OH)6 dimers (C2 symmetry) with the Si-O-Si angle fixed at 5° intervals from 120° to 180°, Si3O2(OH)8 linear trimers (C2 symmetry) with varying Si-O-Si angles, Si3O3(OH)6 three-membered rings (D3 and C1 symmetries), Si4O4(OH)8 four-membered ring (C4 symmetry) and Si8O12(OH)8 octamer (D4 symmetry). The calculated 29Si, 17O and 1H isotropic chemical shifts (δiSi, δiO and δiH) for these clusters are all close to experimental NMR data for similar local structures in crystalline silicates. The calculated 17O quadrupolar coupling constants (QCC) of the bridging oxygens (Si-O-Si) are also in good agreement with experimental data. The calculated 17O QCC of silanols (Si-O-H) are much larger than those of the bridging oxygens, but unfortunately there are no experimental data for similar groups in well-characterized crystalline phases for comparison. There is a good correlation between δiSi and the mean Si-O-Si angle for both Q1 and Q2, where Qn denotes Si with n other tetrahedral Si next-nearest neighbors. Both the δiO and the 17O electric field gradient asymmetry parameter, η of the bridging oxygens have been found to depend strongly on the O site symmetry, in addition to the Si-O-Si angle. On the other hand, the 17O QCC seems to be influenced little by structural parameters other than the Si-O-Si angle, and is thus expected to be the most reliable 17O NMR parameter that can be used to decipher Si-O-Si angle distribution information. Both the 17O QCC and the 2H QCC of silanols decrease with decreasing length of hydrogen bond to a second O atom

  19. On the introduction of 17O+p reaction rates evaluated through the THM in AGB nucleosynthesis calculations

    NASA Astrophysics Data System (ADS)

    Palmerini, S.; Sergi, M. L.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Spitaleri, C.

    2014-05-01

    The rates for the 17O(p,αα14N, 17O(p,α)18F and 18O(p,α)15N reactions deduced trough the Trojan Horse Method (THM) have been introduced into a state-of-the-art asymptotic giant branch (AGB) models for proton-capture nucleosynthesis and cool bottom process. The predicted abundances have been compared with isotopic compositions provided by geochemical analysis of presolar grains. As a result, an improved agreement is found between the models and the isotopic mix of oxide grains of AGB origins, whose composition is the signature of low-temperature proton-capture nucleosynthesis.

  20. Resonance Strength Measurement at Astrophysical Energies: The 17O(p,α)14N Reaction Studied via THM

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Mukhamedzhanov, A.; Irgaziev, B.; Tang, X. D.; Wischer, M.; Mrazek, J.; Kroha, V.

    2016-05-01

    In recent years, the Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of proton-induced reactions on 17O nuclei, overcoming extrapolation procedures and enhancement effects due to electron screening. We will report on the indirect study of the 17O(p,α)14N reaction via the Trojan Horse Method by applying the approach developed for extracting the resonance strength of narrow resonance in the ultralow energy region. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature.

  1. Resonance strength measurement at astrophysical energies: The 17O(p,α)14N reaction studied via Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Mukhamedzhanov, A.; Irgaziev, B.; Tang, X. D.; Wiescher, M.; Mrazek, J.; Kroha, V.

    2015-10-01

    In recent years, the Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of proton-induced reactions on 17O nuclei, overcoming extrapolation procedures and enhancement effects due to electron screening. We will report on the indirect study of the 17O(p,α)14N reaction via the THM by applying the approach developed for extracting the resonance strength of narrow resonance in the ultralow energy region. Two measurements will be described and the experimental THM cross sections will be shown for both experiments.

  2. Potential barriers and Landau-Zener promotion in the inelastic excitation of /sup 17/O by /sup 13/C ions

    SciTech Connect

    Park, J.Y.; Gramlich, K.; Scheid, W.; Greiner, W.

    1986-05-01

    The inelastic excitation of the (1/2)/sup +/ (871 keV) state of /sup 17/O in the reaction of /sup 13/C on /sup 17/O is described by a time-dependent quantum mechanical model with two diabatic states and a classical treatment of the radial relative motion. The structures in the angle-integrated cross section are interpreted as caused by the barriers of the angular momentum-dependent potentials. The transition strength is enhanced by the Landau-Zener effect between the levels considered.

  3. Tracing Atmospheric Sulfate Through a Subalpine Ecosystem Using 17O and 35S, Loch Vale Watershed, Colorado

    NASA Astrophysics Data System (ADS)

    Kester, C. L.; Johnson, C. A.; Mast, M. A.; Michel, R. L.

    2002-12-01

    Over the past several decades, sulfur cycles have been examined in numerous watersheds worldwide to assess the impacts of changes in sulfuric acid deposition rates. A thorough understanding of sulfur behavior in these systems requires that the sulfate influxes from bedrock weathering and from atmospheric deposition be known, and that the extent of sulfur uptake by biomass be determined. Following the discovery of excess 17O in atmospheric sulfate (Lee et al, 2001, GRL 28:1783), we used 17O to help constrain sulfur dynamics and fluxes in alpine/subalpine watersheds in the Rocky Mountains of Colorado (Johnson et al, 2001, GRL 28:4483). Building on this work, and on our previous studies employing cosmogenic 35S (t1/2=87 d, Michel et al, 2000, WRR 36:27), we report a combined 17O-35S study of sulfate in an undisturbed subalpine watershed, Loch Vale, Colorado. In this study, both isotopes were measured in sulfate from a suite of stream and spring waters collected in 1999, and in sulfate from the 1999 snowpack. The snowpack sulfate represents the dominant fraction of annual atmospheric deposition to the watershed. Individual sampling sites show linear correlations between excess 17O and 35S, suggesting that there are two dominant sources of surface water sulfate. The data arrays extend neither toward the measured compositions of snowpack sulfate (Δ17O=1.3‰ , 35S=53 mBq/mg sulfate at Julian day 90), nor toward the compositions characteristic of sulfate from bedrock weathering (Δ17O =0, 35S=0). Thus, the mixing components are themselves composites of different sulfate types. One component appears to be sulfate from bedrock weathering plus atmospheric sulfate with watershed residence times great enough for its 35S to have decayed to below detection (> approx 1 yr). The second mixing component is atmospheric sulfate, a portion of which was subject to redox cycling in soil organic matter - thereby erasing the excess 17O fingerprint - on timescales short enough that 35S is

  4. 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.

  5. Effects of Barrier-Induced Nuclear Spin Magnetization Inhomogeneities on Diffusion-Attenuated MR Signal

    PubMed Central

    Sukstanskii, A.L.; Ackerman, J.J.H.; Yablonskiy, D.A.

    2007-01-01

    The spatial distribution of the transverse nuclear spin magnetization, appearing in a single compartment with impermeable boundaries in a Stejskal-Tanner gradient pulse MR experiment, is analyzed in detail. At short diffusion times the presence of diffusion-restrictive barriers (membranes) reduces effective diffusivity near the membranes and leads to an inhomogeneous spin magnetization distribution (the edge-enhancement effect). In this case, the signal reveals a quasi-two-compartment behavior and can be empirically modeled remarkably well by a biexponential function. The current results provide a framework for interpreting experimental MR data on various phenoma, including water diffusion in giant axons, metabolite diffusion in the brain, and hyperpolarized gas diffusion in lung airways. PMID:14523959

  6. New formulation of Magnetization Equation for Flowing Nuclear Spin under NMR/MRI Excitation(I)

    NASA Astrophysics Data System (ADS)

    de, Dilip; Emetere, Moses; Omotosho, Victor

    2015-03-01

    We have obtained for the first time from the Bloch NMR equations the correct dependence of the single component of magnetization, My and Mz at resonance (NMR/MRI) on relaxation times, rf B1 field (pulsed or continuous), blood(nuclear spin) flow velocity, etc. in the rotating frame of reference. The equations are applicable for both CW and pulsed NMR experiments with or without flow of spins. Our approaches can be extended easily to include gradient fields and diffusion of spins, if needed in NMR/MRI experiments. We also discuss the application of our equations to a specific case of MR excitation scheme: Free induction decay. The first time new equations of single component of MR magnetization and further equations that can be derived with the methodologies used here, can be applied towards accurate simulation of MR images/signals and extraction of parameters of clinical importance through comparison of the measured and the simulated images/signals.

  7. A Magnetic Carbon Sorbent for Radioactive Material from the Fukushima Nuclear Accident

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Daizo; Furukawa, Kazumi; Takasuga, Masaya; Watanabe, Koki

    2014-08-01

    Here we present the first report of a carbon-γ-Fe2O3 nanoparticle composite of mesoporous carbon, bearing COOH- and phenolic OH- functional groups on its surface, a remarkable and magnetically separable adsorbent, for the radioactive material emitted by the Fukushima Daiichi nuclear power plant accident. Contaminated water and soil at a level of 1,739 Bq kg-1 (134Cs and 137Cs at 509 Bq kg-1 and 1,230 Bq kg-1, respectively) and 114,000 Bq kg-1 (134Cs and 137Cs at 38,700 Bq kg-1 and 75,300 Bq kg-1, respectively) were decontaminated by 99% and 90% respectively with just one treatment carried out in Nihonmatsu city in Fukushima. Since this material is remarkably high performance, magnetically separable, and a readily applicable technology, it would reduce the environmental impact of the Fukushima accident if it were used.

  8. Characterization of high-level nuclear waste glass using magnetic measurements

    SciTech Connect

    Senftle, F.E.; Thorpe, A.N.; Grant, J.R.; Barkatt, A.

    1994-12-31

    Magnetic measurements constitute a promising method for the characterization of nuclear waste glasses in view of their simplicity and small sample weight requirements. Initial studies of simulated high-level waste glasses show that the Curie constant is generally a useful indicator of the Fe{sup 2+}:Fe{sup 3+} ratio. Glasses produced by air-cooling in large vessels show systematic deviations between experimental and calcined values, which are indicative of the presence of small amounts of crystalline iron-containing phases. Most of the iron in these phases becomes dissolved in the glass upon re-heating and more rapid quenching. The studies further show that upon leaching the glass in water some of the iron in the surface regions of the glass is converted to a form which has high temperature-independent magnetic susceptibility.

  9. Alternative approach to the standardization of NMR spectra. Direct measurement of nuclear magnetic shielding in molecules.

    PubMed

    Jackowski, Karol; Jaszuński, Michał; Wilczek, Marcin

    2010-02-25

    Exploring the relation between shielding constants, resonance frequencies and magnetic moments of the nuclei we demonstrate that nuclear magnetic shielding can be directly observed from NMR spectra. In this approach, the absolute shielding constants of all the nuclei can be related to a single reference scale, with atomic (3)He as the primary standard. The accuracy of the data obtained using our method is confirmed comparing the (1)H and (13)C shielding constants for a series of deuterated compounds with those determined analyzing the traditional chemical shifts. Since the use of helium-3 is not in general a practical alternative, we next transfer the reference standard to the (2)H signals of external lock solvents, in this way making the method easy and ready for application with most NMR spectrometers. Finally, we illustrate our new method with the measurements of the (2/1)H primary isotope effects in several liquid deuterated solvents. PMID:20112974

  10. Optically Pumped Nuclear Magnetic Resonance near Landau level filling ν = 1/3

    NASA Astrophysics Data System (ADS)

    Khandelwal, P.; Kuzma, N. N.; Barrett, S. E.; Pfeiffer, L. N.; West, K. W.

    1997-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) Using this technique, measurements of the Knight shift (K_S)footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation time (T_1)footnote R. Tycko et al., Science 268, 1460 (1995) have been carried out in the Quantum Hall regimes. In this talk will present our recent measurements of KS and T1 near Landau level filling ν = 1/3, which were carried out in high magnetic fields (up to 12 Tesla) and at low temperatures (T < 1 Kelvin). We will compare these results to the data obtained near ν = 1 and ν = 2/3.

  11. Contributed Review: Nuclear magnetic resonance core analysis at 0.3 T

    SciTech Connect

    Mitchell, Jonathan Fordham, Edmund J.

    2014-11-15

    Nuclear magnetic resonance (NMR) provides a powerful toolbox for petrophysical characterization of reservoir core plugs and fluids in the laboratory. Previously, there has been considerable focus on low field magnet technology for well log calibration. Now there is renewed interest in the study of reservoir samples using stronger magnets to complement these standard NMR measurements. Here, the capabilities of an imaging magnet with a field strength of 0.3 T (corresponding to 12.9 MHz for proton) are reviewed in the context of reservoir core analysis. Quantitative estimates of porosity (saturation) and pore size distributions are obtained under favorable conditions (e.g., in carbonates), with the added advantage of multidimensional imaging, detection of lower gyromagnetic ratio nuclei, and short probe recovery times that make the system suitable for shale studies. Intermediate field instruments provide quantitative porosity maps of rock plugs that cannot be obtained using high field medical scanners due to the field-dependent susceptibility contrast in the porous medium. Example data are presented that highlight the potential applications of an intermediate field imaging instrument as a complement to low field instruments in core analysis and for materials science studies in general.

  12. Applicability of radioactive 99mTc-O4- magnetic fluid to nuclear medicine

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Hee; Kim, Seong-Min; Kim, Keun-Ho; Kim, Chong-Oh

    2011-01-01

    Magnetite nanoparticles were synthesized with solution of ferrous and ferric chlorides and ammonia water by sonochemical method. The hydrophilically radioactive magnetic fluids were prepared by labeling technetium pertechnetate (99mTc-O4-) and then adsorbing alginic acid on the magnetite particles. In order to measure some properties of the dispersed particles, the magnetic fluids were freezed down to -70 oC, and were dried in vacuum. The total size of the particles was about 15 nm with the core diameter of 12 nm and their superparamagnetic saturation magnetization was 63 emu/g for the core-shell of Fe3O4/Algin and 52 emu/g for that of Fe3O4/99mTc-O4-/Algin. The labeling of radioactive 99mTc-O4- to the magnetite particles was efficient to about 70 %. The fluid of magnetic particles on which the radioisotopic substance is labeled with such an efficiency level may be applied as a tracer for diagnosis in nuclear medicine.

  13. Billion-fold enhancement in sensitivity of nuclear magnetic resonance spectroscopy for magnesium ions in solution.

    PubMed

    Gottberg, Alexander; Stachura, Monika; Kowalska, Magdalena; Bissell, Mark L; Arcisauskaite, Vaida; Blaum, Klaus; Helmke, Alexander; Johnston, Karl; Kreim, Kim; Larsen, Flemming H; Neugart, Rainer; Neyens, Gerda; Garcia Ruiz, Ronald F; Szunyogh, Daniel; Thulstrup, Peter W; Yordanov, Deyan T; Hemmingsen, Lars

    2014-12-15

    β-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, β-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. (31)Mg β-NMR spectra are measured for as few as 10(7) magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry. PMID:25303164

  14. Atomic electric dipole moment induced by the nuclear electric dipole moment: The magnetic moment effect

    SciTech Connect

    Porsev, S. G.; Ginges, J. S. M.; Flambaum, V. V.

    2011-04-15

    We have considered a mechanism for inducing a time-reversal violating electric dipole moment (EDM) in atoms through the interaction of a nuclear EDM d{sub N} with the hyperfine interaction, the ''magnetic moment effect''. We have derived the operator for this interaction and presented analytical formulas for the matrix elements between atomic states. Induced EDMs in the diamagnetic atoms {sup 129}Xe, {sup 171}Yb, {sup 199}Hg, {sup 211}Rn, and {sup 225}Ra have been calculated numerically. From the experimental limits on the atomic EDMs of {sup 129}Xe and {sup 199}Hg we have placed the following constraints on the nuclear EDMs, |d{sub N}({sup 129}Xe)|<1.1x10{sup -21}|e|cm and |d{sub N}({sup 199}Hg)|<2.8x10{sup -24}|e|cm.

  15. Nanoscale nuclear magnetic resonance with a 1.9-nm-deep nitrogen-vacancy sensor

    SciTech Connect

    Loretz, M.; Degen, C. L.; Pezzagna, S.; Meijer, J.

    2014-01-20

    We present nanoscale nuclear magnetic resonance (NMR) measurements performed with nitrogen-vacancy (NV) centers located down to about 2 nm from the diamond surface. NV centers were created by shallow ion implantation followed by a slow, nanometer-by-nanometer removal of diamond material using oxidative etching in air. The close proximity of NV centers to the surface yielded large {sup 1}H NMR signals of up to 3.4 μT-rms, corresponding to ∼330 statistically polarized or ∼10 fully polarized proton spins in a (1.8 nm){sup 3} detection volume.

  16. Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

    PubMed

    Sjolander, Tobias F; Tayler, Michael C D; King, Jonathan P; Budker, Dmitry; Pines, Alexander

    2016-06-30

    We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5-5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions. PMID:27243376

  17. Eddy current disruption: effect on nuclear magnetic resonance coil impedance and power loss.

    PubMed

    Harpen, M D

    1989-01-01

    We present a theoretical development and experimental verification of a description of power loss and sample resistance for a lossy sample in a nuclear magnetic resonance radio frequency coil for a sample geometry where the eddy current streamlines are disrupted from their usually assumed circular paths. Specifically treated is the case of a lossy hemisphere. The problem is solved for two orientations; with the induction parallel and perpendicular to the flat surface of the hemisphere. Results of this analysis as well as those for the full sphere as presented by Hoult and Lauterbur are compared with observation for a variety of sample conductivities and orientation. PMID:2811760

  18. Quantitative carbon-13 nuclear magnetic resonance spectroscopic study of mobile residues in bacteriorhodopsin

    SciTech Connect

    Bowers, J.L.; Oldfield, E.

    1988-07-12

    The authors have used quantitative carbon-13 nuclear magnetic resonance (NMR) spectroscopy to study the dynamic structure of the backbone of bacteriorhodopsin in the purple membrane of Halobacterium halobium R/sub 1/ and JW-3. NMR experiments were performed using an internal sucrose quantitation standard on purple membranes in which one of the following /sup 13/C'-labeled amino acids had been biosynthetically incorporated: glycine, isoleucine, lysine, phenylalanine, and valine. The results suggest that the C-terminus of the polypeptide chain backbone, and possibly one of the connecting loops, undergoes rapid, large angle fluctuations. The results are compared with previous NMR and fluorescence spectroscopic data obtained on bacteriorhodopsin.

  19. Material degradation of liquid organic semiconductors analyzed by nuclear magnetic resonance spectroscopy

    SciTech Connect

    Fukushima, Tatsuya; Yamamoto, Junichi; Fukuchi, Masashi; Kaji, Hironori; Hirata, Shuzo; Jung, Heo Hyo; Adachi, Chihaya; Hirata, Osamu; Shibano, Yuki

    2015-08-15

    Liquid organic light-emitting diodes (liquid OLEDs) are unique devices consisting only of liquid organic semiconductors in the active layer, and the device performances have been investigated recently. However, the device degradation, especially, the origin has been unknown. In this study, we show that material degradation occurs in liquid OLEDs, whose active layer is composed of carbazole with an ethylene glycol chain. Nuclear magnetic resonance (NMR) experiments clearly exhibit that the dimerization reaction of carbazole moiety occurs in the liquid OLEDs during driving the devices. In contrast, cleavages of the ethylene glycol chain are not detected within experimental error. The dimerization reaction is considered to be related to the device degradation.

  20. New Approach to High-Pressure Nuclear Magnetic Resonance with Anvil Cells

    NASA Astrophysics Data System (ADS)

    Meissner, T.; Goh, S. K.; Haase, J.; Meier, B.; Rybicki, D.; Alireza, P. L.

    2010-04-01

    A novel approach that uses radio-frequency microcoils in the high-pressure region of anvil cells with Nuclear Magnetic Resonance (NMR) experiments is described. High-sensitivity Al NMR data at 70 kbar for Al metal are presented for the first time. An expected decrease in the Al Knight shift at 70 kbar is observed, as well as an unexpected change in the local charge symmetry at the Al nucleus. The latter is not predicted by chemical structure analysis under high pressure.

  1. Nuclear Magnetic Resonance Studies of Bulk States of Bi2Se3

    NASA Astrophysics Data System (ADS)

    Nisson, D. M.; Dioguardi, A. P.; Klavins, P.; Lin, C. H.; Shirer, K.; Shockley, A.; Crocker, J.; Curro, N. J.; NMR Group Team

    2013-03-01

    We present 209Bi nuclear magnetic resonance (NMR) spectra and relaxation rate data on single crystals of Bi2Se3 grown under various conditions, whose carrier concentrations, resistivities, and Shubnikov-de Haas (SdH) frequencies have been measured. Our NMR data reveal properties of the bulk states, which are influenced by the presence of intrinsic carriers. We find that both the Knight shift and the electric field gradient of the Bi is correlated with carrier concentration, and atypical spectral profiles. Surprisingly, spin-lattice relaxation is not strongly temperature dependent.

  2. Special Features in Application of Nuclear Magnetic Spectroscopy to Study Flows of Liquid Media

    NASA Astrophysics Data System (ADS)

    Davydov, V. V.; Dudkin, V. I.; Karseev, A. Yu.; Vologdin, V. A.

    2016-01-01

    We consider the special features involved in studying flows of liquid media using a nuclear magnetic resonance spectrometer. Taking these special features into account in the design of the NMR spectrometer lets us determine the relative concentrations of paramagnetic ions, and also lets us measure the longitudinal (T1 ) and transverse (T2 ) relaxation times within <0.5% in liquid flows. This lets us completely eliminate errors in determining the state of the flowing medium using the measured relaxation constants T1 and T2, which is especially important when working with medicinal suspensions and biological solutions. We present the results of experimental studies on flows of liquid media.

  3. {sup 1}H nuclear magnetic resonance study of hydrated water dynamics in perfluorosulfonic acid ionomer Nafion

    SciTech Connect

    Han, Jun Hee; Lee, Kyu Won; Jeon, G. W.; Lee, Cheol Eui; Park, W. K.; Choi, E. H.

    2015-01-12

    We have studied the dynamics of hydrated water molecules in the proton exchange membrane of Nafion by means of high-resolution {sup 1}H nuclear magnetic resonance (NMR) measurements. “Bound” and “free” states of hydrated water clusters as well as the exchange protons were identified from the NMR chemical shift measurements, and their activation energies were obtained from the temperature-dependent laboratory- and rotating-frame spin-lattice relaxation measurements. Besides, a peculiar motional transition in the ultralow frequency region was observed at 373 K for the “free” hydrated water from the rotating-frame NMR spin-lattice relaxation time measurements.

  4. Determination of alkylbenzenesulfonate surfactants in groundwater using macroreticular resins and carbon-13 nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thurman, E.M.; Willoughby, T.; Barber, L.B., Jr.; Thorn, K.A.

    1987-01-01

    Alkylbenzenesulfonate surfactants were determined in groundwater at concentrations as low as 0.3 mg/L. The method uses XAD-8 resin for concentration, followed by elution with methanol, separation of anionic and nonionic surfactants by anion exchange, quantitation by titration, and identification by 13C nuclear magnetic resonance spectrometry. Laboratory standards and field samples containing straight-chain and branched-chain alkylbenzenesulfonates, sodium dodecyl sulfate, and alkylbenzene ethoxylates were studied. The XAD-8 extraction of surfactants from groundwater was completed in the field, which simplified sample preservation and reduced the cost of transporting samples.

  5. Characterization of humic acid fractions by C-13 nuclear magnetic resonance spectroscopy

    USGS Publications Warehouse

    Wershaw, R. L.; Thorn, K.A.; Pinckney, D.J.

    1988-01-01

    Soil humic acids from different environments were fractionated by adsorption chromatography on Sephadex and characterized by C-13 nuclear magnetic resonance (NMR) spectroscopy. The C-13 NMR spectra of the fractions consist of some sharp, well-resolved lines and some broad bands in contrast to the spectra of the unfractionated humic acids, where the bands are broader and less well-resolved. The marked increase in resolution is apparently due to increased homogeneity of the fractions. These spectra are compared to the spectra of model compounds.

  6. Probing protein quinary interactions by in-cell nuclear magnetic resonance spectroscopy.

    PubMed

    Majumder, Subhabrata; Xue, Jing; DeMott, Christopher M; Reverdatto, Sergey; Burz, David S; Shekhtman, Alexander

    2015-05-01

    Historically introduced by McConkey to explain the slow mutation rate of highly abundant proteins, weak protein (quinary) interactions are an emergent property of living cells. The protein complexes that result from quinary interactions are transient and thus difficult to study biochemically in vitro. Cross-correlated relaxation-induced polarization transfer-based in-cell nuclear magnetic resonance allows the characterization of protein quinary interactions with atomic resolution inside live prokaryotic and eukaryotic cells. We show that RNAs are an important component of protein quinary interactions. Protein quinary interactions are unique to the target protein and may affect physicochemical properties, protein activity, and interactions with drugs. PMID:25894651

  7. Molecular Structure Laboratory. Fourier Transform Nuclear Magnetic Resonance (FTNMR) Spectrometer and Ancillary Instrumentation at SUNY Geneseo

    SciTech Connect

    Geiger, David K

    2015-12-31

    An Agilent 400-MR nuclear magnetic resonance (NMR) spectrometer and ancillary equipment were purchased, which are being used for molecular structure elucidation.  The instrumentation is housed in a pre-existing facility designed specifically for its use. This instrument package is being used to expand the research and educational efforts of the faculty and students at SUNY-Geneseo and is made available to neighboring educational institutions and business concerns.  Funds were also used for training of College personnel, maintenance of the instrumentation, and installation of the equipment.

  8. Nuclear magnetic resonance study of sulfate reorientations in LiNaSO4.

    PubMed

    Shakhovoy, R A; Rakhmatullin, A; Deschamps, M; Sarou-Kanian, V; Bessada, C

    2016-05-01

    A nuclear magnetic resonance study of the sulfate ion reorientations in β-LiNaSO4 has been carried out. The influence of the SO4 reorientational jumps on the quadrupolar interactions of (7)Li nuclei was investigated by a jump reorientational model, which has not previously been applied to sulfates. The activation energy required for the SO4 reorientations was found to be 0.19 eV. It was also revealed that the SO4 reorientational disorder should be associated with a small anomaly of a heat capacity at around 600 K, which was previously observed experimentally. PMID:27028697

  9. Nuclear magnetic resonance: a key metabolomics platform in the drug discovery process.

    PubMed

    Leenders, Justine; Frédérich, Michel; de Tullio, Pascal

    2015-06-01

    Metabolomics is an innovative tool that is now emerging in the drug discovery process. Indeed, its ability to follow the dynamic perturbations in the metabolome resulting from pathologies but also from drug treatment and or/toxicity is of value for the development of new therapeutic approaches. Nuclear magnetic resonance (NMR) spectroscopy, which is an important analytical technique for several steps of the lead discovery, validation and optimization processes, has been described, together with mass spectrometry (MS) as one of the major platform that could be used for metabolomics studies. This review highlights why NMR could be considered a key tool for the application of metabolomics in drug discovery. PMID:26190682

  10. Nuclear magnetic resonance study of sulfate reorientations in LiNaSO4

    NASA Astrophysics Data System (ADS)

    Shakhovoy, R. A.; Rakhmatullin, A.; Deschamps, M.; Sarou-Kanian, V.; Bessada, C.

    2016-05-01

    A nuclear magnetic resonance study of the sulfate ion reorientations in β-LiNaSO4 has been carried out. The influence of the SO4 reorientational jumps on the quadrupolar interactions of 7Li nuclei was investigated by a jump reorientational model, which has not previously been applied to sulfates. The activation energy required for the SO4 reorientations was found to be 0.19 eV. It was also revealed that the SO4 reorientational disorder should be associated with a small anomaly of a heat capacity at around 600 K, which was previously observed experimentally.

  11. Effect of magnetic quadrupole lens alignment on a nuclear microprobe resolution

    NASA Astrophysics Data System (ADS)

    Kolinko, S. V.; Ponomarev, A. G.

    2016-04-01

    The paper reports the research trends in developing probe-forming systems with high demagnification and analysis factors that limit a nuclear microprobe resolution. Parasitic aberrations caused by tilts and offsets of magnetic quadrupoles are studied in terms of their effect on probe parameters on a target. The most common arrangements of probe-forming systems such as a triplet and "Russian quadruplet" with separated geometry are considered. The accuracy prerequisites for the positioning of the quadrupoles are defined, and practical guidelines for alignment of probe-forming systems with high demagnification factors are suggested.

  12. 1H nuclear magnetic resonance study of distinct interstitial hydrogen dynamics in ZnO

    NASA Astrophysics Data System (ADS)

    Kue Park, Jun; Won Lee, Kyu; Eui Lee, Cheol

    2013-07-01

    A comprehensive 1H nuclear magnetic resonance (NMR) study has been carried out for hydrogen dynamics in a sol-gel-prepared ZnO system. The temperature-dependent linewidth and chemical shift measurements sensitively reflected the proton motions and changes in the local environment. Besides, two types of interstitial proton (Hi+) motions were distinguished from the spin-spin relaxation time measurements, one of them with an activation energy of 0.16 eV and the other with that of 0.33 eV depending on the temperature ranges.

  13. Isotropic proton-detected local-field nuclear magnetic resonancein solids

    SciTech Connect

    Havlin, Robert H.; Walls, Jamie D.; Pines, Alexander

    2004-08-04

    A new nuclear magnetic resonance (NMR) method is presented which produces linear, isotropic proton-detected local-field spectra for InS spin systems in powdered samples. The method, HETeronuclear Isotropic Evolution (HETIE), refocuses the anisotropic portion of the heteronuclear dipolar coupling frequencies by evolving the system under a series of specially designed Hamiltonians and evolution pathways. The theory behind HETIE is represented along with experimental studies conducted on a powdered sample of ferrocene, demonstrating the methodology outlined in this paper. Applications of HETIE for structural determination in solid-state NMR are discussed.

  14. Atomic force microscopy-coupled microcoils for cellular-scale nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Mousoulis, Charilaos; Maleki, Teimour; Ziaie, Babak; Neu, Corey P.

    2013-04-01

    We present the coupling of atomic force microscopy (AFM) and nuclear magnetic resonance (NMR) technologies to enable topographical, mechanical, and chemical profiling of biological samples. Here, we fabricate and perform proof-of-concept testing of radiofrequency planar microcoils on commercial AFM cantilevers. The sensitive region of the coil was estimated to cover an approximate volume of 19.4 × 103 μm3 (19.4 pl). Functionality of the spectroscopic module of the prototype device is illustrated through the detection of 1Η resonance in deionized water. The acquired spectra depict combined NMR capability with AFM that may ultimately enable biophysical and biochemical studies at the single cell level.

  15. 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.

  16. Nanoscale Nuclear Magnetic Resonance with a Nitrogen-Vacancy Spin Sensor

    NASA Astrophysics Data System (ADS)

    Mamin, H. J.; Kim, M.; Sherwood, M. H.; Rettner, C. T.; Ohno, K.; Awschalom, D. D.; Rugar, D.

    2013-02-01

    Extension of nuclear magnetic resonance (NMR) to nanoscale samples has been a longstanding challenge because of the insensitivity of conventional detection methods. We demonstrated the use of an individual, near-surface nitrogen-vacancy (NV) center in diamond as a sensor to detect proton NMR in an organic sample located external to the diamond. Using a combination of electron spin echoes and proton spin manipulation, we showed that the NV center senses the nanotesla field fluctuations from the protons, enabling both time-domain and spectroscopic NMR measurements on the nanometer scale.

  17. Combining Nuclear Magnetic Resonance Spectroscopy and Density Functional Theory Calculations to Characterize Carvedilol Polymorphs.

    PubMed

    Rezende, Carlos A; San Gil, Rosane A S; Borré, Leandro B; Pires, José Ricardo; Vaiss, Viviane S; Resende, Jackson A L C; Leitão, Alexandre A; De Alencastro, Ricardo B; Leal, Katia Z

    2016-09-01

    The experiments of carvedilol form II, form III, and hydrate by (13)C and (15)N cross-polarization magic-angle spinning (CP MAS) are reported. The GIPAW (gauge-including projector-augmented wave) method from DFT (density functional theory) calculations was used to simulate (13)C and (15)N chemical shifts. A very good agreement was found for the comparison between the global results of experimental and calculated nuclear magnetic resonance (NMR) chemical shifts for carvedilol polymorphs. This work aims a comprehensive understanding of carvedilol crystalline forms employing solution and solid-state NMR as well as DFT calculations. PMID:26372719

  18. Experimental study of quantum simulation for quantum chemistry with a nuclear magnetic resonance simulator.

    PubMed

    Lu, Dawei; Xu, Nanyang; Xu, Boruo; Li, Zhaokai; Chen, Hongwei; Peng, Xinhua; Xu, Ruixue; Du, Jiangfeng

    2012-10-13

    Quantum computers have been proved to be able to mimic quantum systems efficiently in polynomial time. Quantum chemistry problems, such as static molecular energy calculations and dynamical chemical reaction simulations, become very intractable on classical computers with scaling up of the system. Therefore, quantum simulation is a feasible and effective approach to tackle quantum chemistry problems. Proof-of-principle experiments have been implemented on the calculation of the hydrogen molecular energies and one-dimensional chemical isomerization reaction dynamics using nuclear magnetic resonance systems. We conclude that quantum simulation will surpass classical computers for quantum chemistry in the near future. PMID:22946038

  19. Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments

    SciTech Connect

    Tang, Yiqiao; Hürlimann, Martin; Mandal, Soumyajit; Paulsen, Jeffrey; Song, Yi-Qiao

    2014-02-21

    A coaxial nuclear magnetic resonance (NMR) probe is built to measure diffusion and relaxation properties of liquid samples. In particular, we demonstrate the acquisition of two-dimensional (2D) distribution functions (T{sub 1}-T{sub 2} and diffusion–T{sub 2}), essential for fluids characterization. The compact design holds promise for miniaturization, thus enabling the measurement of molecular diffusion that is inaccessible to conventional micro-NMR setups. Potential applications range from crude oil characterization to biomolecular screening and detections.

  20. Measurement of nuclear magnetic dipole—dipole couplings in magic angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Tycko, Robert; Dabbagh, Gary

    1990-10-01

    We describe a method for measuring nuclear magnetic dipole—dipole couplings in NMR spectra of solids undergoing rapid magic angle spinning (MAS). We show in theory, simulations, and experiments that the couplings, which are averaged out by MAS alone, can be recovered by applying simple resonant radiofrequency pulse sequences in synchrony with the sample rotation. Experimental 13C dipolar powder pattern spectra of polycrystalline ( 13CH 3) 2C(OH)SO 3Na obtained in a two-dimensional experiment based on this method are presented. The method provides a means of determining internuclear distances in polycrystalline and noncrystalline solids while retaining the high resolution and sensitivity afforded by MAS.

  1. High-resolution proton nuclear magnetic resonance characterization of seminolipid from bovine spermatozoa.

    PubMed

    Alvarez, J G; Storey, B T; Hemling, M L; Grob, R L

    1990-06-01

    The high-resolution one- and two-dimensional proton nuclear magnetic resonance (1H-NMR) characterization of seminolipid from bovine spermatozoa is presented. The 1H-NMR data was confirmed by gas-liquid chromatography-mass spectrometric analysis of the partially methylated alditol acetates of the sugar unit, mild alkaline methanolysis of the glyceryl ester, mobility on normal phase and diphasic thin-layer chromatography (HPTLC), and fast atom bombardment mass spectrometry (FAB-MS). The structure of the molecule corresponds to 1-O-hexadecyl-2-O-hexadecanoyl-3-O-beta-D-(3'-sulfo)-galactopyranosyl- sn-glycerol. PMID:2373957

  2. Development of Nuclear Magnetic Resonance Imaging/spectroscopy for improved petroleum recovery. Final report

    SciTech Connect

    Barrufet, M.A.; Flumerfelt, F.W.; Walsh, M.P.; Watson, A.T.

    1994-04-01

    The overall objectives of this program are to develop and apply Nuclear Magnetic Resonance Imaging (NMRI) and CT X-Ray Scanning methods for determining rock, fluid, and petrophysical properties and for fundamental studies of multiphase flow behavior in porous media. Specific objectives are divided into four subtasks: (1) development of NMRI and CT scanning for the determination of rock-fluid and petrophysical properties; (2) development of NMRI and CT scanning for characterizing conventional multiphase displacement processes; (3) development of NMR and CT scanning for characterizing dispersed phase processes; and (4) miscible displacement studies.

  3. An inexpensive high-throughput nuclear magnetic resonance tube cleaning apparatus.

    PubMed

    Zhang, Bo; Hodgson, James; Hancock, Walter; Powers, Robert

    2011-09-15

    Large-scale nuclear magnetic resonance (NMR) tube cleaning is currently a bottleneck in high-throughput NMR ligand affinity screens. Expensive alternatives include discarding the NMR tubes after a single use (~US $2-$8/tube), using commercial NMR tube cleaners (~$15,000), and abandoning NMR tubes for flow probe technology (~$75,000). Instead, we describe a relatively inexpensive (~$400) and easily constructed apparatus that can clean 180 NMR tubes per hour while using a modest amount of solvent. The application of this apparatus significantly shortens the time to recycle NMR tubes while avoiding cross-contamination and tube damage. PMID:21640698

  4. Efficient dynamic nuclear polarization of phosphorus in silicon in strong magnetic fields and at low temperatures

    NASA Astrophysics Data System (ADS)

    Järvinen, J.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Zvezdov, D.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2014-12-01

    Efficient manipulation of nuclear spins is important for utilizing them as qubits for quantum computing. In this work we report record high polarizations of 31P and 29Si nuclear spins in P-doped silicon in a strong magnetic field (4.6 T) and at temperatures below 1 K. We reached 31P nuclear polarization values exceeding 98 % after 20 min of pumping the high-field electron spin resonance (ESR) line with a very small microwave power of 0.4 μ W . We evaluate that the ratio of the hyperfine-state populations increases by three orders of magnitude after 2 hours of pumping, and an extremely pure nuclear spin state can be created, with less than 0.01 ppb impurities. A negative dynamic nuclear polarization has been observed by pumping the low-field ESR line of 31P followed by the flip-flip cross relaxation, the transition which is fully forbidden for isolated donors. We estimate that while pumping the ESR transitions of 31P also the nuclei of 29Si get polarized, and polarization exceeding 60 % has been obtained. We performed measurements of relaxation rates of flip-flop and flip-flip transitions which turned out to be nearly temperature independent. Temperature dependence of the 31P nuclear relaxation was studied down to 0.75 K, below which the relaxation time became too long to be measured. We found that the polarization evolution under pumping and during relaxation deviates substantially from a simple exponential function of time. We suggest that the nonexponential polarization dynamics of 31P donors is mediated by the orientation of 29Si nuclei, which affect the transition probabilities of the forbidden cross-relaxation processes.

  5. Phonon effects on x-ray absorption and nuclear magnetic resonance spectroscopies

    NASA Astrophysics Data System (ADS)

    Nemausat, Ruidy; Cabaret, Delphine; Gervais, Christel; Brouder, Christian; Trcera, Nicolas; Bordage, Amélie; Errea, Ion; Mauri, Francesco

    2015-10-01

    In material sciences, spectroscopic approaches combining ab initio calculations with experiments are commonly used to accurately analyze the experimental spectral data. Most state-of-the-art first-principles calculations are usually performed assuming an equilibrium static lattice. Yet, nuclear motion affects spectra even when reduced to the zero-point motion at 0 K. We propose a framework based on density-functional theory that includes quantum thermal fluctuations in theoretical x-ray absorption near-edge structure (XANES) and solid-state nuclear magnetic resonance (NMR) spectroscopies and allows to well describe temperature effects observed experimentally. Within the Born-Oppenheimer and quasiharmonic approximations, we incorporate the nuclear motion by generating several nonequilibrium configurations from the dynamical matrix. The averaged calculated XANES and NMR spectral data have been compared to experiments in MgO. The good agreement obtained between experiments and calculations validates the developed approach, which suggests that calculating the XANES spectra at finite temperature by averaging individual nonequilibrium configurations is a suitable approximation. This study highlights the relevance of phonon renormalization and the relative contributions of thermal expansion and nuclear dynamics on NMR and XANES spectra on a wide range of temperatures.

  6. Modeling Nuclear Fusion in High Energy Density Plasmas Using a Strongly Magnetized Non-neutral Plasma

    NASA Astrophysics Data System (ADS)

    Dubin, D. H. E.

    2005-10-01

    In the hot dense interiors of stars and giant planets, nuclear reactions are predicted to occur at rates that are greatly enhanced compared to those at low densities. The enhancement is caused by plasma screening of the reacting pairs, increasing the probability of close collisions. However, strongly enhanced nuclear reaction rates have never been observed in the laboratory. This poster discusses a method for observing the enhancement using an analogy between nuclear energy and cyclotron energy in a non-neutral plasma in a strong magnetic field. In such a plasma, cyclotron energy is an adiabatic invariant, and is released only through close collisions that break this invariant. It is shown that the rate of release of cyclotron energy is enhanced by precisely the same factor as that for the release of nuclear energy, because both processes rely on close collisions that are enhanced by plasma screening.ootnotetextD. Dubin, Phys. Rev. Lett. 94, 025002 (2005). Simulations measuring the screening enhancement will be presented, and the possibility of exciting and studying burn fronts will be discussed.ootnotetextSee also adjacent poster by J. Bollinger.

  7. Time-reversal symmetry violation in molecules induced by nuclear magnetic quadrupole moments.

    PubMed

    Flambaum, V V; DeMille, D; Kozlov, M G

    2014-09-01

    Recent measurements in paramagnetic molecules improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Time-reversal (T) and parity (P) symmetry violation in molecules may also come from their nuclei. We point out that nuclear T, P-odd effects are amplified in paramagnetic molecules containing deformed nuclei, where the primary effects arise from the T, P-odd nuclear magnetic quadrupole moment (MQM). We perform calculations of T, P-odd effects in the molecules TaN, ThO, ThF+, HfF+, YbF, HgF, and BaF induced by MQMs. We compare our results with those for the diamagnetic TlF molecule, where the T, P-odd effects are produced by the nuclear Schiff moment. We argue that measurements in molecules with MQMs may provide improved limits on the strength of T, P-odd nuclear forces, on the proton, neutron, and quark EDMs, on quark chromo-EDMs, and on the QCD θ term and CP-violating quark interactions. PMID:25238355

  8. Diethylstilbestrol can effectively accelerate estradiol-17-O-glucuronidation, while potently inhibiting estradiol-3-O-glucuronidation

    SciTech Connect

    Zhu, Liangliang; Xiao, Ling; Xia, Yangliu; Zhou, Kun; Wang, Huili; Huang, Minyi; Ge, Guangbo; Wu, Yan; Wu, Ganlin; Yang, Ling

    2015-03-01

    This in vitro study investigates the effects of diethylstilbestrol (DES), a widely used toxic synthetic estrogen, on estradiol-3- and 17-O- (E2-3/17-O) glucuronidation, via culturing human liver microsomes (HLMs) or recombinant UDP-glucuronosyltransferases (UGTs) with DES and E2. DES can potently inhibit E2-3-O-glucuronidation in HLM, a probe reaction for UGT1A1. Kinetic assays indicate that the inhibition follows a competitive inhibition mechanism, with the Ki value of 2.1 ± 0.3 μM, which is less than the possible in vivo level. In contrast to the inhibition on E2-3-O-glucuronidation, the acceleration is observed on E2-17-O-glucuronidation in HLM, in which cholestatic E2-17-O-glucuronide is generated. In the presence of DES (0–6.25 μM), K{sub m} values for E2-17-O-glucuronidation are located in the range of 7.2–7.4 μM, while V{sub max} values range from 0.38 to 1.54 nmol/min/mg. The mechanism behind the activation in HLM is further demonstrated by the fact that DES can efficiently elevate the activity of UGT1A4 in catalyzing E2-17-O-glucuronidation. The presence of DES (2 μM) can elevate V{sub max} from 0.016 to 0.81 nmol/min/mg, while lifting K{sub m} in a much lesser extent from 4.4 to 11 μM. Activation of E2-17-O-glucuronidation is well described by a two binding site model, with K{sub A}, α, and β values of 0.077 ± 0.18 μM, 3.3 ± 1.1 and 104 ± 56, respectively. However, diverse effects of DES towards E2-3/17-O-glucuronidation are not observed in liver microsomes from several common experimental animals. In summary, this study issues new potential toxic mechanisms for DES: potently inhibiting the activity of UGT1A1 and powerfully accelerating the formation of cholestatic E2-17-O-glucuronide by UGT1A4. - Highlights: • E2-3-O-glucuronidation in HLM is inhibited when co-incubated with DES. • E2-17-O-glucuronidation in HLM is stimulated when co-incubated with DES. • Acceleration of E2-17-O-glucuronidationin in HLM by DES is via activating the

  9. Magnetization studies of the nuclear spin ordered phases of solid 3He in silver sinters

    NASA Astrophysics Data System (ADS)

    Schuberth, E. A.; Kath, M.; Tassini, L.; Millan-Chacartegui, C.

    2005-08-01

    Solid 3He, in the bcc lattice between 34 and 100 bar, exhibits two nuclear magnetic ordered phases in the sub-mK temperature range, the so called U2D2 low (magnetic) field phase and the “high field phase” above 0.4 T. To determine the exact spin structure of these phases we started a project of neutron scattering from the ordered solid in collaboration with the Hahn-Meitner Institute, Berlin, and other European and US groups. For this experiment it is crucial to grow a single crystal within the sinter needed for cooling the solid to temperatures of the order of 500 μK (or even twenty times lower in the case of the hcp lattice which is formed above 100 bar) and to keep it there long enough to measure a magnetic neutron reflection. We studied the growth of crystals in Ag sinters of different pore size and with different growth speeds to find an optimal way to obtain single crystalline samples. As a first diagnostic step we performed pulsed NMR measurements in the ordered phases of solid 3He in a sinter of 2700 Å particle size down to temperatures of 450 μK at various molar volumes. We could keep the samples in the ordered state for as long as 140 h. The second method we used was SQUID magnetometry. For the low field phase TN was indicated by a drop of the intensity, both in the NMR signal and in the dc magnetization, whereas in the high field phase an increase of about 30% was observed below the ordering temperature. For the fabrication of the sinters a packing fraction of 50% and subsequent annealing proved to be very favorable to obtain cold ordered solid. Furthermore, we find that a paramagnetic surface contribution from a few monolayers of 3He exists down to 500 μK in addition to the bulk magnetization.

  10. Calibrated high-precision 17O-excess measurements using cavity ring-down spectroscopy with laser-current-tuned cavity resonance

    NASA Astrophysics Data System (ADS)

    Steig, E. J.; Gkinis, V.; Schauer, A. J.; Schoenemann, S. W.; Samek, K.; Hoffnagle, J.; Dennis, K. J.; Tan, S. M.

    2014-08-01

    High-precision analysis of the 17O / 16O isotope ratio in water and water vapor is of interest in hydrological, paleoclimate, and atmospheric science applications. Of specific interest is the parameter 17O excess (Δ17O), a measure of the deviation from a~linear relationship between 17O / 16O and 18O / 16O ratios. Conventional analyses of Δ17O of water are obtained by fluorination of H2O to O2 that is analyzed by dual-inlet isotope ratio mass spectrometry (IRMS). We describe a new laser spectroscopy instrument for high-precision Δ17O measurements. The new instrument uses cavity ring-down spectroscopy (CRDS) with laser-current-tuned cavity resonance to achieve reduced measurement drift compared with previous-generation instruments. Liquid water and water-vapor samples can be analyzed with a better than 8 per meg precision for Δ17O using integration times of less than 30 min. Calibration with respect to accepted water standards demonstrates that both the precision and the accuracy of Δ17O are competitive with conventional IRMS methods. The new instrument also achieves simultaneous analysis of δ18O, Δ17O and δD with precision of < 0.03‰, < 0.02 and < 0.2‰, respectively, based on repeated calibrated measurements.

  11. Investigation of enzymatic C-P bond formation using multiple quantum HCP nuclear magnetic resonance spectroscopy.

    PubMed

    Hu, Kaifeng; Werner, Williard J; Allen, Kylie D; Wang, Susan C

    2015-04-01

    The biochemical mechanism for the formation of the C-P-C bond sequence found in l-phosphinothricin, a natural product with antibiotic and herbicidal activity, remains unclear. To obtain further insight into the catalytic mechanism of PhpK, the P-methyltransferase responsible for the formation of the second C-P bond in l-phosphinothricin, we utilized a combination of stable isotopes and two-dimensional nuclear magnetic resonance spectroscopy. Exploiting the newly emerged Bruker QCI probe (Bruker Corp.), we specifically designed and ran a (13) C-(31) P multiple quantum (1) H-(13) C-(31) P (HCP) experiment in (1) H-(31) P two-dimensional mode directly on a PhpK-catalyzed reaction mixture using (13) CH3 -labeled methylcobalamin as the methyl group donor. This method is particularly advantageous because minimal sample purification is needed to maximize product visualization. The observed 3:1:1:3 multiplet specifically and unequivocally illustrates direct bond formation between (13) CH3 and (31) P. Related nuclear magnetic resonance experiments based upon these principles may be designed for the study of enzymatic and/or synthetic chemical reaction mechanisms. PMID:25594737

  12. Monitoring lactic acid production during milk fermentation by in situ quantitative proton nuclear magnetic resonance spectroscopy.

    PubMed

    Bouteille, R; Gaudet, M; Lecanu, B; This, H

    2013-04-01

    When fermenting milk, lactic bacteria convert part of α- and β-lactoses into d- and l- lactic acids, causing a pH decrease responsible for casein coagulation. Lactic acid monitoring during fermentation is essential for the control of dairy gel textural and organoleptic properties, and is a way to evaluate strain efficiency. Currently, titrations are used to follow the quantity of acids formed during jellification of milk but they are not specific to lactic acid. An analytical method without the use of any reagent was investigated to quantify lactic acid during milk fermentation: in situ quantitative proton nuclear magnetic resonance spectroscopy. Two methods using in situ quantitative proton nuclear magnetic resonance spectroscopy were compared: (1) d- and l-lactic acids content determination, using the resonance of their methyl protons, showing an increase from 2.06 ± 0.02 to 8.16 ± 0.74 g/L during 240 min of fermentation; and (2) the determination of the α- and β-lactoses content, decreasing from 42.68 ± 0.02 to 30.76 ± 1.75 g/L for the same fermentation duration. The ratio between the molar concentrations of produced lactic acids and consumed lactoses enabled cross-validation, as the value (2.02 ± 0.18) is consistent with lactic acid bacteria metabolism. PMID:23403188

  13. Nuclear Magnetic Dipole and Electric Quadrupole Moments: Their Measurement and Tabulation as Accessible Data

    SciTech Connect

    Stone, N. J.

    2015-09-15

    The most recent tabulations of nuclear magnetic dipole and electric quadrupole moments have been prepared and published by the Nuclear Data Section of the IAEA, Vienna [N. J. Stone, Report No. INDC(NDS)-0650 (2013); Report No. INDC(NDS)-0658 (2014)]. The first of these is a table of recommended quadrupole moments for all isotopes in which all experimental results are made consistent with a limited number of adopted standards for each element; the second is a combined listing of all measurements of both moments. Both tables cover all isotopes and energy levels. In this paper, the considerations relevant to the preparation of both tables are described, together with observations as to the importance and (where appropriate) application of necessary corrections to achieve the “best” values. Some discussion of experimental methods is included with emphasis on their precision. The aim of the published quadrupole moment table is to provide a standard reference in which the value given for each moment is the best available and for which full provenance is given. A table of recommended magnetic dipole moments is in preparation, with the same objective in view.

  14. Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

    PubMed Central

    Koumoulis, Dimitrios; Morris, Gerald D.; He, Liang; Kou, Xufeng; King, Danny; Wang, Dong; Hossain, Masrur D.; Wang, Kang L.; Fiete, Gregory A.; Kanatzidis, Mercouri G.; Bouchard, Louis-S.

    2015-01-01

    Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive 8Li+ ions that can provide “one-dimensional imaging” in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the 8Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electron–nuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials. PMID:26124141

  15. Nuclear Magnetic Resonance Project at the Medical University of South Carolina

    SciTech Connect

    Lacy, Eric R.

    2008-04-25

    Department of Energy funds were used to support the development of a Center for Marine Structural Biology at the Marine Resources Center at Ft. Johnson in Charleston, South Carolina. The Ft. Johnson site is home to five institutions in a unique state/federal/academic partnership whose member institutions include the National Ocean Service (NOS), the National Institute of Standards and Technology (NIST), the Medical University of South Carolina (MUSC), the SC Department of Natural Resources, and the College of Charleston. The Center for Marine Structural Biology sits adjacent to the newly completed Hollings Marine Laboratory and houses a 700 and 800 MHz nuclear magnetic resource instruments. The completed center is operational and meets it goal to provide state-of-the-art nuclear magnetic resonance capabilities to resolve the molecular structures of compounds that have direct relevance to human health, including marine-derived biotoxins that are tested against cancer cell lines through collaborative studies with researchers at the Hollings Cancer Center at MUSC. Funds from the DOE assisted, in part, with the purchase of NMR probes and ancillary equipment for the 800 MHz NMR instrument. In addition, developmental funds was used to support the visit of an Scientific Advisory Board and for the NMR Planning Team to visit currently operational high field NMR facilities to guide their choice of instrumentation and design of the building.

  16. Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

    NASA Astrophysics Data System (ADS)

    Koumoulis, Dimitrios; Morris, Gerald D.; He, Liang; Kou, Xufeng; King, Danny; Wang, Dong; Hossain, Masrur D.; Wang, Kang L.; Fiete, Gregory A.; Kanatzidis, Mercouri G.; Bouchard, Louis-S.

    2015-07-01

    Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive 8Li+ ions that can provide "one-dimensional imaging" in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the 8Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electron-nuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials.

  17. Investigation of enzymatic C–P bond formation using multiple quantum HCP nuclear magnetic resonance spectroscopy

    PubMed Central

    Hu, Kaifeng; Werner, Williard J.; Allen, Kylie D.; Wang, Susan C.

    2015-01-01

    The biochemical mechanism for the formation of the C–P–C bond sequence found in L-phosphinothricin, a natural product with antibiotic and herbicidal activity, remains unclear. To obtain further insight into the catalytic mechanism of PhpK, the P-methyltransferase responsible for the formation of the second C–P bond in L-phosphinothricin, we utilized a combination of stable isotopes and two-dimensional nuclear magnetic resonance spectroscopy. Exploiting the newly emerged Bruker QCI probe (Bruker Corp.), we specifically designed and ran a 13C-31P multiple quantum 1H-13C-31P (HCP) experiment in 1H-31P two-dimensional mode directly on a PhpK-catalyzed reaction mixture using 13CH3-labeled methylcobalamin as the methyl group donor. This method is particularly advantageous because minimal sample purification is needed to maximize product visualization. The observed 3:1:1:3 multiplet specifically and unequivocally illustrates direct bond formation between 13CH3 and 31P. Related nuclear magnetic resonance experiments based upon these principles may be designed for the study of enzymatic and/or synthetic chemical reaction mechanisms. PMID:25594737

  18. Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators.

    PubMed

    Koumoulis, Dimitrios; Morris, Gerald D; He, Liang; Kou, Xufeng; King, Danny; Wang, Dong; Hossain, Masrur D; Wang, Kang L; Fiete, Gregory A; Kanatzidis, Mercouri G; Bouchard, Louis-S

    2015-07-14

    Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive (8)Li(+) ions that can provide "one-dimensional imaging" in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the (8)Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electron-nuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials. PMID:26124141

  19. 17O(n,α)14C cross section from 25 meV to approximately 1 MeV

    NASA Astrophysics Data System (ADS)

    Koehler, P. E.; Graff, S. M.

    1991-12-01

    We have measured the 17O(n,α)14C cross section from thermal energy to approximately 1 MeV. A bump in the data near 3 keV could be fitted by a state whose properties are consistent with a known subthreshold J π=1- level at Ex=8.039 MeV. The cause of the 1/v cross section near thermal energy could not be determined although the known 2+ state at 8.213 MeV was found to be too narrow to contribute much to the thermal cross section. Our data are compared to measurements made via the inverse reaction. There are many differences between the two sets of data. The astrophysical reaction rate was calculated from the measured cross section. This reaction plays a role in the nucleosynthesis of heavy elements in nonstandard big-bang models. At big-bang temperatures, the experimental rate was found to be in fair agreement with the rate estimated from the previously known properties of states of 18O in this region. Furthermore, using the available information from experiments, it was estimated that the 17O(n,α)14C rate is approximately a factor of 103-104 times larger than the 17O(n,γ)18O rate at big-bang temperatures. As a result, there may be significant cycling between 14C and 17O resulting in a reduction of heavy-element nucleosynthesis.

  20. Synthesis of 5α-androstane-3α,17β-diol 17-O-glucuronide histaminyl conjugate for immunoassays.

    PubMed

    Vinš, Petr; Černý, Ivan; Mikšátková, Petra; Drašar, Pavel

    2016-05-01

    Simple method of preparation of 5α-androstane-3α,17β-diol 17-O-glucuronide N-histaminyl amide was developed for the construction of immunoanalytical kit. Improved method of glucuronide derivative synthesis was used, followed by hydroxybenzotriazole-dicyclohexylcarbodiimide coupling with histamine. PMID:26898541

  1. Effects on ^18F production in novae from changes in the ^17O(p,α)^14N rate

    NASA Astrophysics Data System (ADS)

    Moazen, B. H.; Blackmon, J. C.; Bardayan, D. W.; Chae, K. Y.; Chipps, K.; Domizioli, C. P.; Fitzgerald, R.; Greife, U.; Hix, W. R.; Jones, K. L.; Kozub, R. L.; Lingerfelt, E. J.; Livesay, R. J.; Nesaraja, C. D.; Pain, S. D.; Roberts, L. F.; Shriner, J. F., Jr.; Smith, M. S.; Thomas, J. S.

    2008-04-01

    The properties of a resonance at 183 keV are important for understanding the ^17 O(p,α)^14N and ^17O(p,γ)^18F reaction rates at nova temperatures and was recently reported to significantly increase the (p,α) reaction rate. A method involving the bombardment of a hydrogen filled target chamber was recently developed at ORNL for measuring the strength and energy of (p, α) resonances and was applied to measure this resonance in ^17O(p, α)^14N. The strength of the resonance was confirmed and post-processing nova nucleosynthesis simulations show the new ^17O(p,α)^14N reaction rate significantly decreases ^18F production in low mass ONeMg novae but has little effect on more energetic novae [Moazen et. al. Phys. Rev. C 75 065801 (2007)]. Results and astrophysical implications will be presented as well as future plans to measure ^18F(p,α)^15O with this technique. ORNL is managed by UT Battelle for the US DOE

  2. Computational 17O-NMR spectroscopy of organic acids and peracids: comparison of solvation models.

    PubMed

    Baggioli, Alberto; Crescenzi, Orlando; Field, Martin J; Castiglione, Franca; Raos, Guido

    2013-01-28

    We examine several computational strategies for the prediction of the (17)O-NMR shielding constants for a selection of organic acids and peracids in aqueous solution. In particular, we consider water (the solvent and reference for the chemical shifts), hydrogen peroxide, acetic acid, lactic acid and peracetic acid. First of all, we demonstrate that the PBE0 density functional in combination with the 6-311+G(d,p) basis set provides an excellent compromise between computational cost and accuracy in the calculation of the shielding constants. Next, we move on to the problem of the solvent representation. Our results confirm the shortcomings of the Polarizable Continuum Model (PCM) in the description of systems susceptible to strong hydrogen bonding interactions, while at the same time they demonstrate its usefulness within a molecular-continuum approach, whereby PCM is applied to describe the solvation of the solute surrounded by some explicit solvent molecules. We examine different models of the solvation shells, sampling their configurations using both energy minimizations of finite clusters and molecular dynamics simulations of bulk systems. Hybrid molecular dynamics simulations, in which the solute is described at the PM6 semiempirical level and the solvent by the TIP3P model, prove to be a promising sampling method for medium-to-large sized systems. The roles of solvent shell size and structure are also briefly discussed. PMID:23223608

  3. Investigation of the Herzberg (C1Σ+→A1Π) band system in 12C17O

    NASA Astrophysics Data System (ADS)

    Hakalla, Rafał

    2015-10-01

    The C→A (0,1), (0,2) and (0,3) rovibronic bands of the less-abundant 12C17O isotopologue are studied in high resolution using a high-accuracy dispersive optical spectroscopy in the region of 22,800-26,100 cm-1. Calibration with respect to simultaneously recorded thorium atomic lines, obtained from several overlapped orders of the spectrum in the visible range, as well as a stainless steel hollow-cathode molecular lamp with two anodes, yields an absolute accuracy of wavenumbers measurements of about 0.0025 cm-1 for the CO spectra. All 261 spectra lines of the Herzberg band system in 12C17O, up to Jmax=34, were precisely measured and rotationally analyzed. As a result, the merged rotational constants and rotational equilibrium constants for the C1Σ+ Rydberg state, as well as the band origins, the isotope shifts, the RKR turning points, Franck-Condon factors, relative intensities, and r-centroids of the C→A system in the 12C17O isotopologue were obtained. An experimental RKR potential energy curve and vibrational levels of the C1Σ+ state in 12C17O together with highly excited k3Π, c3Π, E1Π, B1Σ+ and D‧1Σ+ states lying in the region between the first dissociation limit and the ionization potential of CO were plotted. A detailed investigation of possible perturbations that should occur in the C1Σ+(υ=0) Rydberg state of less-abundant 12C17O isotopologue in the close vicinity of the k3Π(υ=1, 2) and c3Π(υ=0) states in the region 92,000 cm-1 was performed. In the A1Π, υ=3 state of 12C17O, extensive, multi-state rotational perturbations were found and analyzed. Also, a global isotopic analysis of the C1Σ+ Rydberg state was carried out in the 12C16O, 12C17O, 13C16O, 12C18O, 13C17O, and 13C18O as well as in 14C16O and 14C18O isotopologues. This analysis enabled us to determine, amongst others, the vibrational equilibrium constants in 12C17O for the C1Σ+ state, to improve these constants in the 12C16O, 13C16O, 12C18O, 13C17O, and 13C18O isotopologues and

  4. 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.

  5. MOA: Magnetic Field Oscillating Amplified Thruster and its Application for Nuclear Electric and Thermal Propulsion

    SciTech Connect

    Frischauf, Norbert; Hettmer, Manfred; Grassauer, Andreas; Bartusch, Tobias; Koudelka, Otto

    2006-07-01

    More than 60 years after the later Nobel laureate Hannes Alfven had published a letter stating that oscillating magnetic fields can accelerate ionised matter via magneto-hydrodynamic interactions in a wave like fashion, the technical implementation of Alfven waves for propulsive purposes has been proposed, patented and examined for the first time by a group of inventors. The name of the concept, utilising Alfven waves to accelerate ionised matter for propulsive purposes, is MOA - Magnetic field Oscillating Amplified thruster. Alfven waves are generated by making use of two coils, one being permanently powered and serving also as magnetic nozzle, the other one being switched on and off in a cyclic way, deforming the field lines of the overall system. It is this deformation that generates Alfven waves, which are in the next step used to transport and compress the propulsive medium, in theory leading to a propulsion system with a much higher performance than any other electric propulsion system. Based on computer simulations, which were conducted to get a first estimate on the performance of the system, MOA is a highly flexible propulsion system, whose performance parameters might easily be adapted, by changing the mass flow and/or the power level. As such the system is capable to deliver a maximum specific impulse of 13116 s (12.87 mN) at a power level of 11.16 kW, using Xe as propellant, but can also be attuned to provide a thrust of 236.5 mN (2411 s) at 6.15 kW of power. While space propulsion is expected to be the prime application for MOA and is supported by numerous applications such as Solar and/or Nuclear Electric Propulsion or even as an 'afterburner system' for Nuclear Thermal Propulsion, other terrestrial applications can be thought of as well, making the system highly suited for a common space-terrestrial application research and utilisation strategy. (authors)

  6. Nuclear magnetic resonance as a method of fluid mobility detection in porous media

    NASA Astrophysics Data System (ADS)

    Zhakov, Sergey; Loskutov, Valentin

    2016-04-01

    The nuclear magnetic resonance (NMR) method is widely used for studying the structure of porous media and processes taking place in such media. This method permits to determine porosity and pore-size distributions, which have direct practical application in various areas. The problem of porous media permeability determination is connected directly with extraction of hydrocarbons from pays and water from aquiferous layers. But it is impossible to measure directly amount of fluid past through the fixes cross section for determination of bed permeability. So various indirect approaches are used to find correlation of permeability value with porosity and pore size distribution which can be determined directly using NMR relaxometry. In contrast to porosity, permeability is dynamic characteristic of porous media so it may be measured correctly only in conditions of moving fluid. Natural porous medium has branched pore structure, so a chaotic component of fluid velocity will occur even for constant mean filtration fluid velocity. In the presence of magnetic field gradient this chaotic fluid velocity will produce additional spin dephasing and decrease of relaxation time [1]. Direct detecting of fluid movement in porous core samples through the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence has been demonstrated and theoretical model and analysis was given. Experiments were made on a set of sandstone samples (Berea, Bentheimer, Castle Gate, Leopard) and with synthetic high-perm samples made of abrasive material. The experiments show that the NMR spin echo measurements permit to fix mean fluid velocity mm/sec. The experiments and the theoretical model show that for low fluid velocities the mean relaxation rate is proportional to fluid velocity . The results may serve as the basis for determination of mobility of liquids in porous media and permeability. 1. P.T.Callaghan. Principles of Nuclear Magnetic Resonance Microscopy. 1991, Oxford University Press.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  8. Effects of magnetic fields on the nuclear burning propagation and the Type Ia SNe runaway

    NASA Astrophysics Data System (ADS)

    Hristov, Boyan; Collins, David C.; Hoeflich, Peter; Weatherford, Charles

    2016-01-01

    The consistency of Type Ia SNe allows for simple descriptions of the phenomena founded on basic physics and yet no theory is able to explain the observations entirely. In particular we are addressing an outstanding problem with current 3D simulations, in which Rayleigh-Taylor (RT) instabilities bring too much burned material to the outer layers thus mixing iron group elements towards the surface but those are not observed. Additionally light curves are reproduced well only in spherically symmetric explosions, while they break down when instabilities are present. We attempt to explain these discrepancies by introducing magnetic fields, which affects the rate of growth of unstable modes. Specifically it increases the growth rate of modes parallel to itself and suppress the transverse modes. This reduces the mixing in two possible ways: stronger burning causes faster pre-expansion, then plumes rise with the similar speed as the surrounding material is expanding; and RT instabilities are suppressed so much that they don't rise at all. Our preliminary models run in a rectangular domain inside a C/O white dwarf (WD) extending 120km along the stellar radius and is about 15km on the side. External magnetic fields between 1e4G and 1e9G are superimposed at various angles to the WD radius. A simple two-species nuclear network is employed in the form of fuel-product (C/O -> 56Ni). The front propagation is modeled as diffusion of the burned fraction of the C/O fuel. All simulations were done with Enzo - a 3D AMR MHD code for astrophysical and cosmological imulations, which was enhanced with additional physics for the nuclear burning. Future work will extend to full star simulations and more complex nuclear networks.

  9. Correction for the 17O interference in δ(13C) measurements when analyzing CO2 with stable isotope mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Assonov, Sergey S.

    2010-01-01

    Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011 180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 – λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygen-bearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.

  10. Nuclear, optical, and magnetic resonance imaging in a mouse mammary window chamber model

    NASA Astrophysics Data System (ADS)

    Leung, Hui Min; Schafer, Rachel; Gmitro, Arthur F.

    2014-09-01

    An orthotopic mouse mammary window chamber (MWC) model has been developed for multimodal in-vivo functional and anatomical imaging of breast cancer xenografts. Capabilities to image numerous physiological aspects of the same tumor microenvironment over time has important applications such as in experiments studying the efficacies of therapeutic interventions, improvement of cancer detection and investigating basic cancer biology. The compatibility of this MWC model with optical, nuclear and magnetic resonance imaging (MRI) makes it possible to perform a multitude of studies ranging from cellular imaging to whole body imaging. Thus, the MWC represents a powerful tool for breast cancer research. Here, two imaging applications are highlighted, namely the nuclear imaging of glycolytic metabolism with 18FFDG and MRI of tissue perfusion. Nuclear imaging is performed with the use of a 3μm thin phosphor scintillator placed directly in contact with the tissue and visible light from the scintillation is directly detected in a low noise, light tight imaging system. Tissue perfusion is imaged either qualitatively with a dynamic contrast enhancement (DCE) MRI technique or quantitatively with an arterial spin labeling flow-sensitive alternating inversion recovery-rapid acquisition with relaxation enhancement (FAIR-RARE) technique.

  11. Cardiovascular imaging in the diagnosis and monitoring of cardiotoxicity: cardiovascular magnetic resonance and nuclear cardiology.

    PubMed

    Pepe, Alessia; Pizzino, Fausto; Gargiulo, Paola; Perrone-Filardi, Pasquale; Cadeddu, Christian; Mele, Donato; Monte, Ines; Novo, Giuseppina; Zito, Concetta; Di Bella, Gianluca

    2016-05-01

    Chemotherapy-induced cardiotoxicity (CTX) is a determining factor for the quality of life and mortality of patients administered potentially cardiotoxic drugs and in long-term cancer survivors. Therefore, prevention and early detection of CTX are highly desirable, as is the exploration of alternative therapeutic strategies and/or the proposal of potentially cardioprotective treatments. In recent years, cardiovascular imaging has acquired a pivotal role in this setting. Although echocardiography remains the diagnostic method most used to monitor cancer patients, the need for more reliable, reproducible and accurate detection of early chemotherapy-induced CTX has encouraged the introduction of second-line advanced imaging modalities, such as cardiac magnetic resonance (CMR) and nuclear techniques, into the clinical setting. This review of the Working Group on Drug Cardiotoxicity and Cardioprotection of the Italian Society of Cardiology aims to afford an overview of the most important findings from the literature about the role of CMR and nuclear techniques in the management of chemotherapy-treated patients, describe conventional and new parameters for detecting CTX from both diagnostic and prognostic perspectives and provide integrated insight into the role of CMR and nuclear techniques compared with other imaging tools and versus the positions of the most important international societies. PMID:27183525

  12. 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.

  13. 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

  14. On the possibility of determining the thermodynamic temperature of colloid solutions by the nuclear magnetic resonance method

    NASA Astrophysics Data System (ADS)

    Davydov, V. V.; Dudkin, V. I.

    2016-07-01

    A new method of determining the thermodynamic temperature of colloid solutions placed onto a sealed glass vessel is considered; the method is based on measurements of the magnetic susceptibility in flowing liquid by the magnetic nuclear resonance method. Experimental results show that the Curie law holds for colloid solutions in the temperature range of 278-333 K, in which ferrofluid cells prepared based on these solutions are used.

  15. Local moment and inhomogeneous hyperfine interaction in the CuO2 plane of Bi2Sr2CaCu2O8+δ (Bi2212) single crystal by ^17O NMR

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Mukhopadhyay, Sutirtha; Halperin, William

    2007-03-01

    The ^17O NMR spectra of Bi2Sr2CaCu2O8+δ (Bi2212) single crystals were measured in the magnetic field of 8 T from 4 K to 200 K. The linewidth of the oxygen in CuO2 plane, O(1), was found to follow a Curie temperature dependence in the normal state, where the Curie coefficient decreases with the increase of δ oxygen in the crystal. In the superconductive state, it decreases with deceasing temperature, proportional to the decreasing Knight shift. This temperature dependence of the linewidth identifies the existence of local moment and inhomogeneous hyperfine interaction in the CuO2 plane.

  16. Intracellular water in Artemia cysts (brine shrimp): Investigations by deuterium and oxygen-17 nuclear magnetic resonance.

    PubMed

    Kasturi, S R; Seitz, P K; Chang, D C; Hazlewood, C F

    1990-08-01

    The dormant cysts of Artemia undergo cycles of hydration-dehydration without losing viability. Therefore, Artemia cysts serve as an excellent intact cellular system for studying the dynamics of water-protein interactions as a function of hydration. Deuterium spin-lattice (T(1)) and spin-spin (T(2)) relaxation times of water in cysts hydrated with D(2)O have been measured for hydrations between 1.5 and 0.1 g of D(2)O per gram of dry solids. When the relaxation rates (I/T(1), I/T(2)) of (2)H and (17)O are plotted as a function of the reciprocal of hydration (1/H), an abrupt change in slope is observed near 0.6 g of D(2)O (or H(2) (17)O)/gram of dry solids, the hydration at which conventional metabolism is activated in this system. The results have been discussed in terms of the two-site and multisite exchange models for the water-protein interaction as well as protein dynamics models. The (2)H and (17)O relaxation rates as a function of hydration show striking similarities to those observed for anisotropic motion of water molecules in protein crystals.It is suggested here that although the simple two-site exchange model or n-site exchange model could be used to explain our data at high hydration levels, such models are not adequate at low hydration levels (<0.6 g H(2)O/g) where several complex interactions between water and proteins play a predominant role in the relaxation of water nuclei. We further suggest that the abrupt change in the slope of I/T(1) as a function of hydration in the vicinity of 0.6 g H(2)O/g is due to a change in water-protein interactions resulting from a variation in the dynamics of protein motion. PMID:19431762

  17. C++ OPPS, a new software for the interpretation of protein dynamics from nuclear magnetic resonance measurements

    NASA Astrophysics Data System (ADS)

    Zerbetto, Mirco; Polimeno, Antonino; Meirovitch, Eva

    Nuclear magnetic resonance (NMR) is a powerful tool for elucidating protein dynamics because of the possibility to interpret nuclear spin relaxation properties in terms of microdynamic parameters. Magnetic relaxation times T1, T2, and NOE depend on dipolar and quadrupolar interactions, on chemical shift anisotropy and cross-correlation effects. Within the framework of given motional model, it is possible to express the NMR relaxation times as functions of spectral densities (Abragam, The Principles of Nuclear Magnetism; Oxford University Press: Clarendon, London, 1961), obtaining the connection between macroscopic observables and microscopic properties. In this context, recently Meirovitch et al. (Shapiro et al., Biochemistry 2002, 41, 6271, Meirovitch et al., J Phys Chem B 2006, 110, 20615, Meirovitch et al., J Phys Chem B 2007, 111, 12865) applied the dynamical model introduced by Polimeno and Freed (Polimeno and Freed, Adv Chem Phys 1993, 83, 89, Polimeno and Freed, J Phys Chem 1995, 99, 10995), known as the slowly relaxing local structure (SRLS) model, to the study of NMR data. The program C++OPPS (http://www.chimica.unipd.it/licc/), developed in our laboratory, implements the SRLS model in an user-friendly way with a graphical user interface (GUI), introduced to simplify the work to users who do not feel at ease with the complex mathematics of the model and the difficulties of command line based programs. The program is an evolution of the old FORTRAN 77 implementation COPPS (COupled Protein Probe Smoluchowski) and presents a number of new features: the presence of an easy to use GUI written in JAVA; high calculation performance thanks to features of C++ language, employment of BLAS (basic linear algebra subprograms) library (Blackford et al., Trans Math Soft 2002, 28, 135) in handling matrix-vector operations and parallelization of the code under the MPI (message passing interface) paradigm (Gropp et al., Parallel Comput 1996, 22, 789, Gropp and Lusk, User

  18. Rationale for the combination of nuclear medicine with magnetic resonance for pre-clinical imaging.

    PubMed

    Wagenaar, Douglas J; Kapusta, Maciej; Li, Junqiang; Patt, Bradley E

    2006-08-01

    Multi-modality combinations of SPECT/CT and PET/CT have proven to be highly successful in the clinic and small animal SPECT/CT and PET/CT are becoming the norm in the research and drug development setting. However, the use of ionizing radiation from a high-resolution CT scanner is undesirable in any setting and particularly in small animal imaging (SAI), in laboratory experiments where it can result in radiation doses of sufficient magnitude that the experimental results can be influenced by the organism's response to radiation. The alternative use of magnetic resonance (MR) would offer a high-resolution, non-ionizing method for anatomical imaging of laboratory animals. MR brings considerably more than its 3D anatomical capability, especially regarding the imaging of laboratory animals. Dynamic MR imaging techniques can facilitate studies of perfusion, oxygenation, and diffusion amongst others. Further, MR spectroscopy can provide images that can be related to the concentration of endogenous molecules in vivo. MR imaging of injected contrast agents extends MR into the domain of molecular imaging. In combination with nuclear medicine (NM) SPECT and PET modalities in small animal imaging, MR would facilitate studies of dynamic processes such as biodistribution, pharmacokinetics, and pharmacodynamics. However, the detectors for nearly all PET and SPECT systems are still based on vacuum tube technology, namely: photomultiplier tubes (PMT's) in which the signal is generated by transporting electrons over a substantial distance within an evacuated glass tube, making them inoperable in even small magnetic fields. Thus the combination of SPECT or PET with MR has not been practical until the recent availability of semiconductor detectors such as silicon avalanche photodiodes (APD's) for PET and CdZnTe (CZT) detectors for SPECT coupled with the availability of high-density low noise ASIC electronics to read out the semiconductor detectors. The strong advantage of these

  19. Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal.

    PubMed

    Lintuvuori, Juho; Straka, Michal; Vaara, Juha

    2007-03-01

    We present constant-pressure Monte Carlo simulations of nuclear magnetic resonance (NMR) spectral parameters, nuclear magnetic shielding relative to the free atom as well as nuclear quadrupole coupling, for atomic xenon dissolved in a model thermotropic liquid crystal. The solvent is described by Gay-Berne (GB) molecules with parametrization kappa=4.4, kappa{'}=20.0 , and mu=nu=1 . The reduced pressure of P{*}=2.0 is used. Previous simulations of a pure GB system with this parametrization have shown that upon lowering the temperature, the model exhibits isotropic, nematic, smectic- A , and smectic- B /molecular crystal phases. We introduce spherical xenon solutes and adjust the energy and length scales of the GB-Xe interaction to those of the GB-GB interaction. This is done through first principles quantum chemical calculations carried out for a dimer of model mesogens as well as the mesogen-xenon complex. We preparametrize quantum chemically the Xe nuclear shielding and quadrupole coupling tensors when interacting with the model mesogen, and use the parametrization in a pairwise additive fashion in the analysis of the simulation. We present the temperature evolution of {129/131}Xe shielding and 131Xe quadrupole coupling in the different phases of the GB model. From the simulations, separate isotropic and anisotropic contributions to the experimentally available total shielding can be obtained. At the experimentally relevant concentration, the presence of the xenon atoms does not significantly affect the phase behavior as compared to the pure GB model. The simulations reproduce many of the characteristic experimental features of Xe NMR in real thermotropic LCs: Discontinuity in the value or trends of the shielding and quadrupole coupling at the nematic-isotropic and smectic-A-nematic phase transitions, nonlinear shift evolution in the nematic phase reflecting the behavior of the orientational order parameter, and decreasing shift in the smectic-A phase. The last

  20. Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal

    NASA Astrophysics Data System (ADS)

    Lintuvuori, Juho; Straka, Michal; Vaara, Juha

    2007-03-01

    We present constant-pressure Monte Carlo simulations of nuclear magnetic resonance (NMR) spectral parameters, nuclear magnetic shielding relative to the free atom as well as nuclear quadrupole coupling, for atomic xenon dissolved in a model thermotropic liquid crystal. The solvent is described by Gay-Berne (GB) molecules with parametrization κ=4.4 , κ'=20.0 , and μ=ν=1 . The reduced pressure of P⋆=2.0 is used. Previous simulations of a pure GB system with this parametrization have shown that upon lowering the temperature, the model exhibits isotropic, nematic, smectic- A , and smectic- B /molecular crystal phases. We introduce spherical xenon solutes and adjust the energy and length scales of the GB-Xe interaction to those of the GB-GB interaction. This is done through first principles quantum chemical calculations carried out for a dimer of model mesogens as well as the mesogen-xenon complex. We preparametrize quantum chemically the Xe nuclear shielding and quadrupole coupling tensors when interacting with the model mesogen, and use the parametrization in a pairwise additive fashion in the analysis of the simulation. We present the temperature evolution of Xe129/131 shielding and Xe131 quadrupole coupling in the different phases of the GB model. From the simulations, separate isotropic and anisotropic contributions to the experimentally available total shielding can be obtained. At the experimentally relevant concentration, the presence of the xenon atoms does not significantly affect the phase behavior as compared to the pure GB model. The simulations reproduce many of the characteristic experimental features of Xe NMR in real thermotropic LCs: Discontinuity in the value or trends of the shielding and quadrupole coupling at the nematic-isotropic and smectic- A -nematic phase transitions, nonlinear shift evolution in the nematic phase reflecting the behavior of the orientational order parameter, and decreasing shift in the smectic- A phase. The last