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Sample records for nmr spin-hamiltonian parameters

  1. Density functional theory calculations of the nuclear magnetic resonance spin-Hamiltonian parameters for two polyamines of prostate tissue: spermidine and spermine

    International Nuclear Information System (INIS)

    1H nuclear magnetic resonance (NMR) spin-Hamiltonian parameters: chemical shifts ? and spin–spin coupling constants J have been calculated for the two polyamines: spermidine and spermine present in prostate tissue. Molecules in the gas phase as well as in solution in water have been investigated using density functional theory calculations. From calculated ? and J values, NMR spectra have been simulated and compared to the experimental ones we acquired at 400 MHz for each polyamine in solution in D2O. From these comparisons, reliable NMR parameters are proposed for spermidine and spermine, among which the J constants were until now unknown for these two molecules

  2. Theoretical investigations of the local structure and the spin Hamiltonian parameters for Ti2+ in MgCl2

    International Nuclear Information System (INIS)

    The local structure and spin Hamiltonian parameters (zero-field splitting and g factors) for Ti2+ in MgCl2 are theoretically studied using the perturbation formulas of these parameters for a 3d2 ion under trigonally distorted octahedra. The contributions from the dynamical Jahn–Teller effect, the configuration interactions and the ligand orbital and spin–orbit coupling interactions are quantitatively involved based on the cluster approach in a uniform way. The chlorine polyhedron around the impurity Ti2+ is found to transform from a slightly compressed octahedron in pure MgCl2 to a slightly elongated one, characterized by the local angular decrease of 0.3° related to the host bond angle 54.78° due to the Jahn–Teller effect. The calculated spin Hamiltonian parameters based on the above trigonal elongation show good agreement with the experimental data. The results are discussed

  3. On the non-standard rhombic spin Hamiltonian parameters derived from Moessbauer spectroscopy and magnetism-related measurements

    International Nuclear Information System (INIS)

    The orthorhombic standardization of spin Hamiltonian parameters is increasingly adopted in the electron magnetic resonance area. The aim of this paper is to elucidate the ramifications of orthorhombic standardization for other spectroscopic and magnetic techniques, which also employ the spin Hamiltonian formalism. This is illustrated by examples derived from the Moessbauer spectroscopy, magnetic moments and magnetic susceptibility, photoinduced changes of magnetization, and other magnetism-related measurements. Implications of standardization in the studies of magnetic ordering, Haldane gap for integer spin systems, the macroscopic quantum tunnelling of magnetization, specific heat measurements, the spin wave theory, and inelastic neutron scattering are also discussed. Several sets of the non-standard zero-field splitting (ZFS) parameters for transition ions at orthorhombic symmetry sites, expressed in various notations and units, are standardized. Calculations are performed using the computer package CST, which yields the standardized ZFS parameter sets. The results are presented in a unified way in the extended Stevens notation bkq and units of cm-1 together with the conventional D and E parameters, which prevail in the studies dealt with in this paper. This enables a direct comparison with the available data for similar ion/host systems. The standardization reveals several inconsistencies in interpretation of the experimental data o interpretation of the experimental data obtained by various techniques

  4. Spin-Hamiltonian parameters and defect structure for the tetragonal Mo5+ center in the reduced BaTiO3:Mo crystal

    International Nuclear Information System (INIS)

    The spin-Hamiltonian parameters (g factors g?, g? and hyperfine structure constants A?, A?) of the tetragonal Mo5+ center in reduced BaTiO3:Mo crystal with low temperature phase are calculated from the high-order perturbation formulas based on the two-mechanism model for d1 ions in octahedral clusters with the ground state 2B2 (|dxy?). In the model, both the contributions to spin-Hamiltonian parameters from the crystal-field (CF) mechanism and that from the charge-transfer (CT) mechanism (which is neglected in the widely-used crystal field theory) are considered. The calculated results are in reasonably agreement with the experimental values. The calculations show that for the spin-Hamiltonian parameters of BaTiO3:Mo5+, the relative importances of CT mechanism |QCT/QCF| are about 17%, 9%, 7% and 7% for Q=?g?, ?g?, A?(2), and A?(2) (where ?g=g?ge, ge?2.0023, the g factor of free electron), respectively. It appears that for the high valence state dn ion clusters in crystals, the precise and complete calculations of spin-Hamiltonian parameters should take both the CF and CT mechanisms into account. The tetragonally-compressed distortion of (MoO6)7? octahedral clusters in the low-temperature rhombohedral phase of BaTiO3 caused by the static Jahn–Teller effect is also acquired from the calculations. The results are discussed. - Highlights: • Spin-Hamiltonian parameters of Mo5+ in rhombohedral BaTiO3 are calculated. • The calculation is based on the two (CF and CT)-mechanism model. • Contribution due to the charge-transfer mechanism should be considered. • Calculation confirms the defect model and obtains the defect structural data

  5. Local structure distortion and spin Hamiltonian parameters of oxide-diluted magnetic semiconductor Mn-doped ZnO

    International Nuclear Information System (INIS)

    The local structure distortion, the spin Hamiltonian (SH) parameters, and the electric fine structure of the ground state for Mn2+ (3d5) ion in ZnO crystals are systematically investigated, where spin–spin (SS), spin–other-orbit (SOO) and orbit–orbit (OO) magnetic interactions, besides the well-known spin-orbit (SO) coupling, are taken into account for the first time, by using the complete diagonalization method. The theoretical results of the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), the Zeeman g-factors: g// and g?, and the energy differences of the ground state: ?1 and ?2 for Mn2+ in Mn2+: ZnO are in good agreement with experimental measurements when the three O2– ions below the Mn2+ ion rotate by 1.085° away from the [111]-axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Mn2+ ions in Mn2+: ZnO crystals. It is found for Mn2+ ions in Mn2+: ZnO crystals that although the SO mechanism is the most important one, the contributions to the SH parameters, made by other four mechanisms, i.e. SS, SOO, OO, and SO?SS?SOO?OO mechanisms, are significant and should not be omitted, especially for calculating ZFS parameter D. (condensed matter: electronic structure, electrical, magnetic, and optical propnetic, and optical properties)

  6. Spin-Hamiltonian parameters of Gd{sup 3+} ion in the room temperature tetragonal phase of BaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wei-Qing [Southwest Jiaotong Univ., Chengdu (China). Key Laboratory of Advanced Technologies of Materials; University of Electronic Science and Technology of China, Chengdu (China). State Key Laboratory of Electronic Thin Films and Integrated Devices; Zheng, Wen-Chen [Sichuan Univ., Chengdu (China). Dept. of Material Science

    2014-10-15

    The spin-Hamiltonian parameters (g factors g {sub vertical} {sub stroke} {sub vertical} {sub stroke}, g {sub perpendicular} {sub to}, and zero-field splittings b{sub 2}{sup 0}, b{sub 4}{sup 0}, b{sub 4}{sup 4}, b{sub 6}{sup 0}, b{sub 6}{sup 4}) of the 4f{sup 7} Gd{sup 3+} ion in the tetragonal phase of a BaTiO{sub 3} crystal are calculated through the diagonalization (of energy matrix) method based on the one-electron crystal field mechanism. In the calculations, the crystal field parameters are estimated from the superposition model with the structural data of the studied crystal. It is found that by using three adjustable intrinsic parameters anti A{sub k}(R{sub 0}) (k = 2, 4, 6) in the superposition model, the seven calculated spin-Hamiltonian parameters are in good agreement with the experimental values, suggesting that the diagonalization method based on one-electron crystal field mechanism is effective in the studies of spin-Hamiltonian parameters for 4f{sup 7} ions in crystals.

  7. Microscopic spin-Hamiltonian parameters and crystal field energy levels for the low C3 symmetry Ni2+ centre in LiNbO3 crystals

    International Nuclear Information System (INIS)

    The microscopic spin-Hamiltonian (MSH) parameters and the crystal field (CF) energy levels for Ni2+ ions in LiNbO3 crystals have been investigated using the crystal field analysis/microscopic spin-Hamiltonian package recently developed. The investigations considered for the first time the spin-spin (SS) and spin-other-orbit (SOO) interactions. The low-symmetry effects (LSE) arising from the additional terms (Im(B43)?0) induced at the C3 symmetry sites by the distortion angle ?, which have been omitted in earlier works, have also been dealt with. This study shows that for LiNbO3 : Ni2+ the contributions arising from SS and SOO interactions to the zero-field splitting parameter D are appreciable, whereas those to g|| and gp-erpendicular are quite small. Since the distortion angle ? ( congruent with 0.68 deg. ) for LiNbO3 : Ni2+ is rather small, the contributions to the spin-Hamiltonian (SH) parameters arising from LSE are also small. Feasibility of application of the superposition model is also discussed. A good overall agreement between the theoretical and experimental results for the SH parameters and the CF energy levels has been obtained

  8. Spin-Hamiltonian parameters and local structures of the tetragonal (CrO4)3- clusters in Cr5+-doped KDP-type crystals

    Science.gov (United States)

    Mei, Yang; Peng, Ren-Ming; Wei, Cheng-Fu; Zheng, Wen-Chen

    2014-05-01

    The spin-Hamiltonian parameters (g factors g//, g? and hyperfine structure constants A//, A?) of tetragonal (CrO4)3- clusters in Cr5+-doped KDP-type crystals KH2PO4, KD2PO4, NH4H2PO4, ND4D2PO4, KH2AsO4, KD2AsO4 and NH4AsO4 are calculated from the high-order perturbation formulas based on the two-mechanism model for the elongated d1 tetrahedral clusters in crystals with the ground state |d>. In the model, the contributions to spin-Hamiltonian parameters from both the crystal field (CF) mechanism and the charge-transfer (CT) mechanism (the latter is neglected in the widely-applied CF theory) are included. On the basis of the calculated values and by taking account of the small admixture of the first excited state |d> to the ground state |d> due to the vibrational motion of ligands (this dynamic effect leads a twinkling elongated tetrahedron to become a compressed one), all the calculated spin-Hamiltonian parameters are in reasonable agreement with the experimental values. The difficulty in the explanation of spin-Hamiltonian parameters by using the conventional static contributions for these Cr5+-doped KDP-type crystals are overcome, and the impurity-induced static local structures of (CrO4)3- clusters (which are different from the corresponding ones in the host crystals) in KDP-type crystals are estimated. The results are discussed.

  9. Studies on the local angular distortion and spin Hamiltonian parameters for the trigonal Co{sup 2+} center in MgCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xian-Fen [University of Electronic Science and Technology of China, Chengdu (China). School of Physical Electronics; Southwest University of Science and Technology of China, Mianyang (China). School of Science; Wu, Shao-Yi; Kuang, Min-Quan; Li, Guo-Liang [University of Electronic Science and Technology of China, Chengdu (China). School of Physical Electronics

    2014-10-15

    The local angular distortion and spin Hamiltonian parameters (g factor g {sub vertical} {sub stroke} {sub vertical} {sub stroke}, g {sub perpendicular} {sub to} and the hyperfine structure constants) for the trigonal Co{sup 2+} center in MgCl{sub 2} are theoretically studied by diagonalizing the 6 x 6 energy matrix of ground {sup 4}T{sub 1} state for a trigonally distorted octahedral 3d{sup 7} cluster. Based on the cluster approach, the contributions from the admixtures of various J (= 1/2, 3/2, 5/2) states and the ligand orbital and spin-orbit coupling interactions are taken into account in a uniform way. The local impurity-ligand bond angle in the Co{sup 2+} center is found to be about 3.44 larger than the host metal-ligand bond angle in the pure crystal due to substitution of smaller Mg{sup 2+} by bigger Co{sup 2+}, inducing a further compressed ligand octahedron. The calculated spin Hamiltonian parameters using the above local angular distortion are in good agreement with the experimental data. The present studies on the local structure and the spin Hamiltonian parameters for Co{sup 2+} in MgCl{sub 2} are tentatively extended to a more general case by comparing the relevant impurity behaviours for Co{sup 2+} in various trigonal environments.

  10. Theoretical study on the local structure and the spin-Hamiltonian parameters for Ni2+ ions at Nb sites in LiNbO3 crystal

    International Nuclear Information System (INIS)

    The relations between the spin-Hamiltonian (SH) parameters and crystal structure of LiNbO3:Ni2+ crystal have been established using the SH theory. On this basis, the SH parameters of LiNbO3:Ni2+ crystal have been calculated. The calculated results are in good agreement with experimental data, and this shows that the model adopted is reasonable. Also, the contributions to SH parameters from spin triplets and spin singlets are discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Spin-spin and spin-other-orbit effects of optical spectra and the spin-Hamiltonian parameters for Cr3+ ions in MgO crystals

    International Nuclear Information System (INIS)

    An extended complete diagonalization method/microscopic spin-Hamiltonian (CDM/MSH) program has been developed, which is applicable for d3 ions at sites of tetragonal symmetry type I (C4v, D2d, D4, D4h) and trigonal symmetry type I (C3v, D3, D3d). The Hamiltonian includes the spin-spin (SS) and spin-other-orbit (SOO) magnetic interactions besides the spin-orbit (SO) magnetic interaction usually taken into account. Utilizing the extended CDM/MSH program, the optical spectra, the spin-Hamiltonian (SH) parameters of the ground state 4B1, and the splitting ?(2E) of the first excited 2E state for Cr3+ (3d3) ions at C4v symmetry sites in MgO crystals have been successfully investigated. It is found that although the SO magnetic interaction is the most important one, the contributions to the SH parameters and the optical spectra from the SS and SOO magnetic interactions for Cr3+:MgO crystals are appreciable and should not be omitted, especially reaching 27.8% for the zero field splitting parameter D

  12. Calculations of spin Hamiltonian parameters and analysis of trigonal distortions in LiSr(Al,Ga)F{sub 6}:Cr{sup 3+} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Brik, M.G. [Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)]. E-mail: brik@ksc.kwansei.ac.jp; Avram, C.N. [Department of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223 Timisoara (Romania); Avram, N.M. [Department of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223 Timisoara (Romania)

    2006-10-01

    The effective spin-Hamiltonian (SH) parameters (zero-field splitting D and g factors g {sub -}parallel and g {sub -}perpendicular ) for Cr{sup 3+} ions in LiSr(Al,Ga)F{sub 6} crystals are calculated from the complete high-order perturbation formulae for a d{sup 3} ion. Parameters of trigonal crystal field acting on the Cr{sup 3+} ion are calculated. The magnitude of trigonal distortion of the [CrF{sub 6}]{sup 3-} clusters is related to the experimental measurements of the spin-Hamiltonian parameters in the considered systems. Since in both crystals g{sub parallel}

  13. Semi-empirical and ab initio DFT modeling of the spin-Hamiltonian parameters for Fe6+: K2MO4 (M = S, Cr, Se)

    Science.gov (United States)

    Avram, N. M.; Brik, M. G.; Andreici, E.-L.

    2014-09-01

    In this paper we calculated the spin-Hamiltonian parameters (g factors {{g}||}, {{g}\\bot } and zero field splitting parameter D) for Fe6+ ions doped in K2MO4 (M = S, Cr, Se) crystals, taking into account the actual site symmetry of the Fe6+ impurity ion. The suggested method is based on the successful application of two different approaches: the crystal field theory (CFT) and density functional based (DFT). Within the CFT model we used the cluster approach and the perturbation theory method, based on the crystal field parameters, which were calculated in the superposition model. Within the DFT approach the calculations were done at the self-consistent field (SCF) by solving the coupled perturbed SCF equations. Comparison with experimental data shows that the obtained results are quite satisfactory, which proves applicability of the suggested calculating technique.

  14. Studies of the spin-Hamiltonian parameters and defect structures for Gd3+ ions in zircon-structure silicates MSiO4 (M=Zr, Hf, Th).

    Science.gov (United States)

    Yang, Wei-Qing; Zheng, Wen-Chen

    2011-09-01

    The spin-Hamiltonian parameters (g factors g?, g? and zero-field splittings b2(0), b4(0), b4(4), b6(0), b6(4)) for 4f7 ion Gd3+ at the tetragonal M4+ site of zircon-structure silicates MSiO4 (M=Zr, Hf, Th) are calculated from a diagonalization (of energy matrix) method. The Hamiltonian concerning this energy matrix contains the free-ion, crystal-field interaction and Zeeman interaction terms and the 56×56 energy matrix is constructed by considering the ground multiplet 8S7/2 and the excited multiplets 6L7/2 (L=P, D, F, G, H, I). The defect structures of Gd3+ centers in the three MSiO4 crystals are yielded from the calculation. The results are discussed. PMID:21665526

  15. Studies of the spin Hamiltonian parameters for Gd3+ in Pr1.98Gd0.02CuO4

    International Nuclear Information System (INIS)

    The spin Hamiltonian parameters (i.e., zero-field splittings (ZFSs) b20, b40, b44 and the g factor) for the tetragonal Gd3+ in Pr1.98Gd0.02CuO4 are studied from the superposition model and the approximation formula including admixture of the ground 8S7/2 and the excited 6L7/2 (L = P, D, F, G) states via the spin-orbit coupling interactions, respectively. The calculated ZFSs and g factor are in reasonable agreement with the experimental data. It is found that the impurity-ligand bonding angles related to the fourfold (C4) axis in the impurity Gd3+ centre are about 0.710 smaller than those in the host

  16. Theoretical investigations of the spin-Hamiltonian parameters and local structural distortion of Fe3+: ZnAl2O4 crystals

    Science.gov (United States)

    Yang, Zi-Yuan

    2014-10-01

    The relations between the spin-Hamiltonian (SH) parameters and the structural parameters of the Fe3+ ions in Fe3+: ZnAl2O4 crystals have been established by means of the microscopic spin Hamiltonian theory and the superposition model (SPM). On the basis of this, the local structure distortion, the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors g factors: g//, g?, and ?g(=g// - g?) for Fe3+ ions in Fe3+: ZnAl2O4 crystals, for the first time taking into account the electronic magnetic interactions, i.e. the spin-spin (SS), the spin-other-orbit (SOO), and the orbit-orbit (OO) interactions, besides the well-known spin-orbit (SO) interaction, are theoretically investigated using complete diagonalization method (CDM). This investigation reveals that the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe3+ ions in Fe3+: ZnAl2O4 crystals. The theoretical second-order ZFS parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors: g//, g?, and ?g of the ground state for Fe3+ ion in Fe3+: ZnAl2O4 crystals yield a good agreement with experiment findings by taking into account the lattice distortions: ?R = 0.0191 nm and ?? = 0.076°. In conclusion, our research shows that there is a slight local structure distortion for Fe3+ ions in Fe3+: ZnAl2O4 crystals, but the site of Fe3+ still retains D3d symmetry. On the other hand, it is found for Fe3+ ions in Fe3+: ZnAl2O4 crystals that the SO mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the SS, SOO, OO, and SO?SS?SOO?OO mechanisms are not appreciable, especially for the ZFS parameter D.

  17. Theoretical studies of the spin Hamiltonian parameters and local structures for the tetragonal Cu{sup 2+} and Ni{sup 3+} centers in Mg{sub 2}TiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hua-Ming, E-mail: huamingzhang66@gmail.com [Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang 330063 (China); Wan, Xiong; Zhang, Zhi-Ming [Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang 330063 (China)

    2013-02-05

    Highlights: Black-Right-Pointing-Pointer Spin Hamiltonian parameters and local structures are analyzed for the impurity Cu{sup 2+} and Ni{sup 3+} centers in Mg{sub 2}TiO{sub 4}. Black-Right-Pointing-Pointer Ligand orbital and spin-orbit coupling contributions are included from the cluster approach due to moderate covalency. Black-Right-Pointing-Pointer Ligand octahedra experience relative elongations along C{sub 4} axis due to Jahn-Teller effect. - Abstract: The local structures of the two impurity Cu{sup 2+} (and Ni{sup 3+}) centers with low spin (S = 1/2) in Mg{sub 2}TiO{sub 4} are theoretically studied by using the perturbation formulas of the spin Hamiltonian parameters for 3d{sup 9} (and 3d{sup 7}) ions in tetragonally elongated octahedra. In these formulas, the tetragonal field parameters are quantitatively determined using the superposition model and the local structures of the impurity Cu{sup 2+} (and Ni{sup 3+}) centers, and the ligand orbital and spin-orbit coupling contributions are included on the basis of the cluster approach in view of moderate covalency for the studied systems. The [CuO{sub 6}]{sup 10-} and [NiO{sub 6}]{sup 9-}clusters on the substitutional Mg{sup 2+} site are found to suffer relative elongations by about {Delta}Z{sub Cu} ( Almost-Equal-To 3.2%) and {Delta}Z{sub Ni} ( Almost-Equal-To 0.7%) for the impurity Cu{sup 2+} and Ni{sup 3+} centers, respectively, along the C{sub 4} axis due to the Jahn-Teller effect. The calculated spin Hamiltonian parameters based on the above Jahn-Teller elongations show good agreement with the observed values. The results are discussed.

  18. Supersymmetric analysis of a spin Hamiltonian model

    Science.gov (United States)

    Demircio?lu, B.; Bilge Ocak, S.; Kuru, ?.

    2006-04-01

    The intertwining method has been applied to the effective potential of the spin Hamiltonian H=-?Sz2-BS. The supersymmetric partner potentials, some of which are singular, are obtained by using low-lying states of this potential. Applying the intertwining method successively, hierarchy of effective potentials has been established. Supersymmetric partner of the transformed spin Hamiltonian's effective potential has also been constructed.

  19. Theoretical investigations of the microscopic spin Hamiltonian parameters including the spin-spin and spin-other-orbit interactions for Ni2+(3d8) ions in trigonal crystal fields

    International Nuclear Information System (INIS)

    The microscopic origin of the spin Hamiltonian (SH) parameters for Ni2+(3d8) ions in a trigonal type I symmetry (C3v,D3d,D3) crystal field (CF) is studied. In addition to the spin-orbit (SO) interaction, we consider also the spin-spin (SS) and spin-other-orbit (SOO) interactions. The relative importance of the four (SO, SS, SOO, and combined SO-SS-SOO) contributions to the SH parameters is investigated using the CFA/MSH package and the complete diagonalization method (CDM). The SO mechanism is dominant for all CF parameter (CFP) ranges studied, except where the contributions DSO to the zero-field splitting (ZFS) parameter D change sign. For the trigonal CFP, vc ? 1200cm-1D due to the other three mechanisms exceeds DSO. Although vertical bar DSOO vertical bar is quite small, the combined vertical bar DSO-SOO vertical bar is appreciable. The SO-based perturbation theory (PT) works generally well for the g-factors: gparallel and gperp, while it fails for D in the vicinity of vc and for large vertical bar v' vertical bar and v>0. The high percentage discrepancy ratio ?D = 2020% for vc indicates unreliability of DSO (in PT). Applications to Ni2+ ions at trigonal symmetry sites in LiNbO3, ?-LiIO3, and Al2O3, are provided. The theore3, are provided. The theoretical SH parameters are in good agreement with the experimental data. The low symmetry (C3) effects induced by the angle ? are tentatively studied, but appear to be quite small

  20. Gravitational spin Hamiltonians from the S matrix

    CERN Document Server

    Vaidya, Varun

    2014-01-01

    We utilize generalized unitarity and recursion relations combined with effective field theory(EFT) techniques to compute spin dependent interaction terms for inspiralling binary systems in the post newtonian(PN) approximation. Using these methods offers great computational advantage over traditional techniques involving feynman diagrams, especially at higher orders in the PN expansion. As a specific example, we reproduce the spin-orbit interaction up to 2.5 PN order as also the leading order $S^2$(3PN) hamiltonian for an arbitrary massive object. We also obtain the unknown $S^3$(3.5PN) spin hamiltonian for an arbitrary massive object in terms of its low frequency linear response to gravitational perturbations, which was till now known only for a black hole. Furthermore, we derive the missing $S^4$ Hamiltonian at leading order(4PN) for an arbitrary massive object and establish that a minimal coupling of a massive elementary particle to gravity leads to a black hole structure. Finally, the Kerr metric is obtain...

  1. Gravitational spin Hamiltonians from the S matrix

    Science.gov (United States)

    Vaidya, Varun

    2015-01-01

    We utilize generalized unitarity and recursion relations combined with effective field theory techniques to compute spin-dependent interaction terms for an inspiralling binary system in the post-Newtonian (PN) approximation. Using these methods offers great computational advantage over traditional techniques involving Feynman diagrams, especially at higher orders in the PN expansion. As a specific example, we reproduce the spin-orbit (up to 2.5PN order) and the leading-order S2 (2PN) Hamiltonian for a binary system with one of the massive objects having nonzero spin using the S -matrix elements of elementary particles. For the same system, we also obtain the S3 (3.5PN) spin Hamiltonian for an arbitrary massive object, which was until now known only for a black hole. Furthermore, we derive the missing S4 Hamiltonian at leading order (4PN), again for an arbitrary massive object and establish that the minimal coupling of an elementary particle to gravity automatically captures the physics of a spinning black hole. Finally, the Kerr metric is obtained as a series in GN by comparing the action of a test particle in the vicinity of a spinning black hole to the derived potential.

  2. Quantum chemical calculations of NMR parameters.

    Czech Academy of Sciences Publication Activity Database

    Schöfberger, W.; Sychrovský, Vladimír; Trantírek, Lukáš

    Dordrecht : Springer, 2006 - (Šponer, J.; Lankaš, F.), s. 513-536 ISBN 978-1-4020-4794-7. - (Challenges and Advances in Computional Chemistry and Physics. 2) R&D Projects: GA ?R GA203/05/0388; GA MŠk(CZ) 1K04011 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z60220518 Keywords : NMR * quantum chemical calculations * chemical shielding * spin-spin coupling Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Magnetic response of the J1-J2 spin Hamiltonian from classical Monte Carlo and Schwinger boson mean field theory

    OpenAIRE

    Yang, Zhihua; Kim, Jung Hoon; Han, Jung Hoon

    2009-01-01

    Magnetic susceptibilities at several potential ordering wave vectors (0,0), (\\pi,0), and (\\pi,\\pi) are analyzed for the antiferromagnetic J1-J2 spin Hamiltonian by classical Monte Carlo and Schwinger boson mean field theories over the parameter range 0 \\le 2J_2/J_1 \\le 2. We find a nearly linear-T behavior of the uniform susceptibility that extends up to the temperature scale of J_1 within both calculation schemes when 2J_2/J_1 is sufficiently removed from the critical point...

  4. Magnetic interactions and microscopic spin Hamiltonian approaches for 3d3 ions at trigonal symmetry sites

    International Nuclear Information System (INIS)

    The spin-Hamiltonian (SH) parameters (D, g//, and g-bar ) for 4A2(3d3)-state ions at trigonal symmetry sites, taking into account the spin-spin (SS), the spin-other-orbit (SOO), the orbit-orbit (OO) magnetic interactions besides the well-known spin-orbit (SO) magnetic interaction, are studied in the intermediate-field coupling scheme using the CDM/MSH (Complete Diagonalization Method/ Microscopic Spin Hamiltonian) program recently developed. It is shown that the SH parameters arise from five microscopic mechanisms including SO coupling mechanism, SS coupling mechanism, SOO coupling mechanism, OO coupling mechanism, and SO-SS-SOO-OO combined coupling mechanism. The relative importance of the five (SO, SS, SOO, OO and combined SO-SS-SOO-OO) contributions to the SH parameters is investigated. It is shown that the SO coupling mechanism in these coupling mechanisms is the most important one. The effect of the OO coupling mechanism on the energy levels is appreciable whereas that on the SH parameters is negligible. The contribution from the SS coupling mechanism to the zero-field splitting (ZFS) parameter D is appreciable but is quite small to g-factors: g// and g-bar . In contrast, the contribution from the SOO coupling mechanism to the ZFS parameter D is quite small but is appreciable to g-factors. Two perturbation theory method approaches have been examined using CDM/MSH program. It is found thaned using CDM/MSH program. It is found that the analytical expressions developed by Macfarlane for D, g//, and g-bar work well in most of the CF ranges considered whereas those developed by Zdansky for D do not work well in almost all the CF ranges considered. The illustrative evaluation is performed for typical laser material Cr3+: Al2O3. The good agreements between the theoretical values and the experimental finding are obtained. It is found that the percentage difference ?D(=|DTotal(CDM)-DSO(CDM)|/|DTotal(CDM)|x100%) reaches 20.9% for laser material Cr3+: Al2O3. The investigation indicates that the contribution to the ZFS parameter D from the SS and SOO magnetic interactions should not be omitted.

  5. Mean-field theory of antiferromagnetic spin Hamiltonian with four spin interactions for bcc lattice

    International Nuclear Information System (INIS)

    An antiferromagnetic spin Hamiltonian with four spin interactions for bcc lattice is investigated on the assumption of four sublattices within the mean-field approximation. Phase diagrams are calculated in the parameter space for zero field. They possess a weak ferromagnetic phase. The effects of the magnetic field on the model are discussed in detail. The susceptibility of the antiferromagnetic phase becomes dependent on temperature in contrast to the usual cases. There is the case where the susceptibility of the SCAF perpendicular phase in the magnetic field on the spin plane can become much larger than the perpendicular susceptibility of this phase. On the basis of these results we examine to what extent this model can be compatible with the recent experimental results obtained in solid 3He. The magnitudes of exchange integrals are determined so as to fit to low-temperature behavior as well as high-temperature behavior of solid 3He. For these parameter values, it is shown that the paramagnetic phase undergoes a second-kind transition into the AF phase. In this phase the susceptibility increases more rapidly with lowering temperature than the extrapolation of the high-temperature Curie-Weiss law, and it shows a sudden drop to a nearly constant value from a peak value at T sub(c1), where this phase makes a first-kind transition to the SCAF parallel phase contrary to the case of Hetherington and Willard. This behavior is qualitatively similar to This behavior is qualitatively similar to that of the solid 3He. (author)

  6. Modeling Ne-21 NMR parameters for carbon nanosystems.

    Czech Academy of Sciences Publication Activity Database

    Kupka, T.; Nieradka, M.; Kaminský, Jakub; Stobinski, L.

    2013-01-01

    Ro?. 51, ?. 10 (2013), s. 676-681. ISSN 0749-1581 R&D Projects: GA ?R GAP208/11/0105; GA MŠk(CZ) LH11033 Grant ostatní: AV ?R(CZ) M200551205 Institutional support: RVO:61388963 Keywords : Ne-21 NMR * GIAO NMR * molecular modeling * carbon nanostructures Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.559, year: 2013

  7. Theory of Half-Metallic Double Perovskites II: Effective Spin Hamiltonian and Disorder Effects

    OpenAIRE

    Erten, Onur; Meetei, O. Nganba; Mukherjee, Anamitra; Randeria, Mohit; Trivedi, Nandini; Woodward, Patrick

    2012-01-01

    Double perovskites like Sr$_2$FeMoO$_6$ are materials with half-metallic ground states and ferrimagnetic T$_{\\rm{c}}$'s well above room temperature. This paper is the second of our comprehensive theory for half metallic double perovskites. Here we derive an effective Hamiltonian for the Fe core spins by "integrating out" the itinerant Mo electrons and obtain an unusual double square-root form of the spin-spin interaction. We validate the classical spin Hamiltonian by compari...

  8. Spin Hamiltonian, order out of a Coulomb phase, and pseudocriticality in the frustrated pyrochlore Heisenberg antiferromagnet FeF3

    Science.gov (United States)

    Sadeghi, Azam; Alaei, Mojtaba; Shahbazi, Farhad; Gingras, Michel J. P.

    2015-04-01

    FeF3, with its half-filled Fe3 +3 d orbital, hence zero orbital angular momentum and S =5 /2 , is often put forward as a prototypical highly frustrated classical Heisenberg pyrochlore antiferromagnet. By employing ab initio density functional theory, we obtain an effective spin Hamiltonian for this material. This Hamiltonian contains nearest-neighbor antiferromagnetic Heisenberg, biquadratic, and Dzyaloshinskii-Moriya interactions as dominant terms and we use Monte Carlo simulations to investigate the nonzero temperature properties of this minimal model. We find that upon decreasing temperature, the system passes through a Coulomb phase, composed of short-range correlated coplanar states, before transforming into an "all-in/all-out" (AIAO) state via a very weakly first-order transition at a critical temperature Tc?22 K, in good agreement with the experimental value for a reasonable set of Coulomb interaction U and Hund's coupling JH describing the material. Despite the transition being first order, the AIAO order parameter evolves below Tc with a power-law behavior characterized by a pseudo "critical exponent" ? ?0.18 in accord with experiment. We comment on the origin of this unusual ? value.

  9. Practical Model Fitting Approaches to the Direct Extraction of NMR Parameters Simultaneously from All Dimensions of Multidimensional NMR Spectra

    International Nuclear Information System (INIS)

    A maximum likelihood (ML)-based approach has been established for the direct extraction of NMR parameters (e.g., frequency, amplitude, phase, and decay rate) simultaneously from all dimensions of a D-dimensional NMR spectrum. The approach, referred to here as HTFD-ML (hybrid time frequency domain maximum likelihood), constructs a time-domain model composed of a sum of exponentially-decaying sinusoidal signals. The apodized Fourier transform of this time-domain signal is a model spectrum that represents the 'best fit' to the equivalent frequency-domain data spectrum. The desired amplitude and frequency parameters can be extracted directly from the signal model constructed by the HTFD-ML algorithm. The HTFD-ML approach presented here, as embodied in the software package CHIFIT, is designed to meet the challenges posed by model fitting of D-dimensional NMR data sets, where each consists of many data points (108 is not uncommon) encoding information about numerous signals (up to 105 for a protein of moderate size) that exhibit spectral overlap. The suitability of the approach is demonstrated by its application to the concerted analysis of a series of ten 2D 1H-15N HSQC experiments measuring 15N T1 relaxation. In addition to demonstrating the practicality of performing maximum likelihood analysis on large, multidimensional NMR spectra, the results demonstrate that this parametric model-fitting approach provides more accurate amplitude and frequency estimates than those obtude and frequency estimates than those obtained from conventional peak-based analysis of the FT spectrum. The improved performance of the model fitting approach derives from its ability to take into account the simultaneous contributions of all signals in a crowded spectral region (deconvolution) as well as to incorporate prior knowledge in constructing models to fit the data

  10. NMR evidence for higher-order multipole order parameters in NpO2.

    Science.gov (United States)

    Tokunaga, Y; Aoki, D; Homma, Y; Kambe, S; Sakai, H; Ikeda, S; Fujimoto, T; Walstedt, R E; Yasuoka, H; Yamamoto, E; Nakamura, A; Shiokawa, Y

    2006-12-22

    We report a microscopic investigation of multipolar order parameters in the ordered state of NpO2 conducted via 17O NMR on a single crystal. From the angular dependence of hyperfine fields at 17O nuclei, we have obtained clear evidence for the appearance of field-induced antiferro-octupolar as well as field-induced antiferro-dipolar moments below T0 = 26 K. We have also observed oscillatory spin-echo decay, which is well understood in terms of small electric field gradients created by antiferro-quadrupolar ordering. This reveals that the quadrupolar order parameter is directly observable by means of NMR. The present NMR studies provide definitive support for a proposed longitudinal triple-q type octupolar-quadrupolar ordering model for NpO2. PMID:17280392

  11. The Model of the Theory of the Quantum Brain Dynamics can be cast on the Heisenberg Spin Hamiltonian

    OpenAIRE

    Ohsaku, Tadafumi

    2003-01-01

    In this note, we show that the model of the quantum brain dynamics can be cast on a kind of the Heisenberg spin Hamiltonian. Therefore, we would like to emphasize that the quantum dynamics of brain should be understood by the physics of quantum spin systems.

  12. 1H and 13C NMR for determining average molecular parameters of asphaltenes from vacuum residue distillation

    International Nuclear Information System (INIS)

    The aim of this work was to obtain average molecular parameters by using some analytical techniques, namely NMR (1H and 13C NMR), vapor pressure osmometry (VPO), and elemental analysis. NMR provided particular information on important molecular parameters such as aromatic carbon fraction, aliphatic carbons fraction, alkyl-substituted aromatic carbons, unsubstituted aromatic carbons, among others. Molecular modeling was employed to build the structure of asphaltenes using the experimental data. (author)

  13. ESR and NMR study of mixed yttrium-lutetium-aluminum garnets

    International Nuclear Information System (INIS)

    ESR of Mo3+ ions and NMR of 27Al nuclei is investigated in mixed single crystals of yttrium-lutetium-aluminium garnets (Ysub(1-x)Lusub(x))3Al5O12, where 0 3+ and 27Al compared with Y3Al5O12 and Lu3Al5O12 single crystals are revealed associated with symmetry and crystalline field parameter changes at isomorphous substitution of Y3+ ions in the rare-earth sublattice of the garnet by those of Lu3+. Symmetry, nearest coordination, and parameters of spin-Hamiltonians are estimated concerning all of Mo3+ and 27Al centres in (Ysub(1-x)Lusub(x))3Al5O12 at x < 0.15. (author)

  14. NMR Principles

    OpenAIRE

    Hore, Pj

    2010-01-01

    The basic theory behind NMR spectroscopy is described. The various NMR parameters that can be obtained from NMR spectra are explained, including the chemical shift, spin-spin coupling, and relaxation. Some explanation of the theory of how NMR is detected is also presented. © 1999 Elsevier Ltd All rights reserved.

  15. Low-field NMR logging sensor for measuring hydraulic parameters of model soils

    Science.gov (United States)

    Sucre, Oscar; Pohlmeier, Andreas; Minière, Adrien; Blümich, Bernhard

    2011-08-01

    SummaryKnowing the exact hydraulic parameters of soils is very important for improving water management in agriculture and for the refinement of climate models. Up to now, however, the investigation of such parameters has required applying two techniques simultaneously which is time-consuming and invasive. Thus, the objective of this current study is to present only one technique, i.e., a new non-invasive method to measure hydraulic parameters of model soils by using low-field nuclear magnetic resonance (NMR). Hereby, two model clay or sandy soils were respectively filled in a 2 m-long acetate column having an integrated PVC tube. After the soils were completely saturated with water, a low-field NMR sensor was moved up and down in the PVC tube to quantitatively measure along the whole column the initial water content of each soil sample. Thereafter, both columns were allowed to drain. Meanwhile, the NMR sensor was set at a certain depth to measure the water content of that soil slice. Once the hydraulic equilibrium was reached in each of the two columns, a final moisture profile was taken along the whole column. Three curves were subsequently generated accordingly: (1) the initial moisture profile, (2) the evolution curve of the moisture depletion at that particular depth, and (3) the final moisture profile. All three curves were then inverse analyzed using a MATLAB code over numerical data produced with the van Genuchten-Mualem model. Hereby, a set of values ( ?, n, ?r and ?s) was found for the hydraulic parameters for the soils under research. Additionally, the complete decaying NMR signal could be analyzed through Inverse Laplace Transformation and averaged on the 1/ T2 space. Through measurement of the decay in pure water, the effect on the relaxation caused by the sample could be estimated from the obtained spectra. The migration of the sample-related average with decreasing saturation speaks for a enhancement of the surface relaxation as the soil dries, in concordance with results found by other authors. In conclusion, this low-field mobile NMR technique has proven itself to be a fast and a non-invasive mean to investigate the hydraulic behavior of soils and to explore microscopical aspect of the water retained in them. In the future, the sensor should allow easy soil moisture measurements on-field.

  16. Surface-induced order parameter distortion in superfluid ³He-B measured by nonlinear NMR.

    Science.gov (United States)

    Levitin, Lev V; Bennett, Robert G; Surovtsev, Evgeny V; Parpia, Jeevak M; Cowan, Brian; Casey, Andrew J; Saunders, John

    2013-12-01

    The B phase of superfluid 3He is a three-dimensional time-reversal invariant topological superfluid, predicted to support gapless Majorana surface states. We confine superfluid 3He into a thin nanofluidic slab geometry. In the presence of a weak symmetry-breaking magnetic field, we have observed two possible states of the confined 3He-B phase manifold, through the small tipping angle NMR response. Large tipping angle nonlinear NMR has allowed the identification of the order parameter of these states and enabled a measurement of the surface-induced gap distortion. The results for two different quasiparticle surface scattering boundary conditions are compared with the predictions of weak-coupling quasiclassical theory. We identify a textural domain wall between the two B phase states, the edge of which at the cavity surface is predicted to host gapless states, protected in the magnetic field. PMID:24476290

  17. Exact two-component relativistic theory for NMR parameters: general formulation and pilot application.

    Science.gov (United States)

    Sun, Qiming; Xiao, Yunlong; Liu, Wenjian

    2012-11-01

    The previously proposed exact two-component (X2C) relativistic theory of nuclear magnetic resonance (NMR) parameters [Q. Sun, W. Liu, Y. Xiao, and L. Cheng, J. Chem. Phys. 131, 081101 (2009)] is reformulated to accommodate two schemes for kinetic balance, five schemes for magnetic balance, and three schemes for decoupling in a unified manner, at both matrix and operator levels. In addition, three definitions of spin magnetization are considered in the coupled-perturbed Kohn-Sham equation. Apart from its simplicity, the most salient feature of X2C-NMR lies in that its diamagnetic and paramagnetic terms agree individually with the corresponding four-component counterparts for any finite basis. For practical applications, five approximate schemes for the first order coupling matrix X(10) and four approximate schemes for the treatment of two-electron integrals are introduced, which render the computations of X2C-NMR very much the same as those of approximate two-component approaches. PMID:23145715

  18. NMR and FTIR characterization of petroleum residues: structural parameters and correlations

    Scientific Electronic Library Online (English)

    Alexandre T., Castro.

    2006-10-01

    Full Text Available Resíduos pesados de petróleo podem ser usados como matéria-prima na produção de diversos materiais de carbono, como piches, isotrópicos e anisotrópicos, e diferentes tipos de coque. A caracterização química destes resíduos, e de materiais de carbono em geral, é um desafio que deve ser abordado para [...] que se possa otimizar adequadamente estes processos de produção. Neste trabalho, resíduos de petróleo de diferentes refinarias foram analisados por RMN, FTIR e análise elementar. Parâmetros de análise foram otimizados para a técnica de RMN e espectroscopia no infravermelho por refletância difusa, uma técnica geralmente aplicada a materiais sólidos, mas que gerou espectros de boa qualidade para estas amostras. Correlações foram encontradas entre os índices de aromaticidade por RMN e FTIR, um parâmetro largamente usado no estudo da formação da mesofase, bem como entre a razão C/H e o índice de aromaticidade. Outros parâmetros estruturais de interesse também foram determinados. Abstract in english Heavy petroleum residues can be used as raw materials in the production of various carbon products, notably isotropic and anisotropic pitches and different types of coke. The chemical characterization of these residues, and carbon materials in general, is a challenge that has to be addressed in orde [...] r to allow the adequate optimization of production processes. In this study, petroleum residues of different refineries were studied by NMR, FTIR and elemental analysis. Optimum parameters were determined for NMR analysis and diffuse reflectance spectroscopy (DRIFTS), a technique that is usually applied to solid materials but was shown to yield good quality spectra for these samples. Correlations were found between NMR and FTIR results for the aromaticity index, a structural parameter widely used in the study of mesophase formation in pitches, as well as between C/H ratios and the aromaticity index. Other structural parameters of interest were also obtained.

  19. Quantum model of a solid-state spin qubit: Ni cluster on a silicon surface by the generalized spin Hamiltonian and X-ray absorption spectroscopy investigations

    CERN Document Server

    Farberovich, Oleg V; Soldatov, Alexander V

    2014-01-01

    We present here the quantum model of a Ni solid-state electron spin qubit on a silicon surface with the use of a density functional scheme for calculation of the exchange integrals in the non-collinear spin configurations in the generalized spin Hamiltonian (GSH) with the anisotropic exchange couplings parameters linking the nickel ions with a silicon substrate. In this article we offer the model of the quantum solid-state N-spin qubit based on the studying of the spin structure and the spin-dynamics simulations of the 3d-metal Ni clusters on a silicon surface. The solution of the problem of the entanglement between a spin states in N-spin systems is becoming more interesting when considering clusters or molecules with a spectral gap in their density of states. For quantifying the distribution of the entanglement between the individual spin eigenvalues (modes) in the spin structure of the N-spin system we use the density of entanglement. We have studied the Rabi oscillations to evaluate the N-spin qubits syst...

  20. Thermal and solvent effects on NMR spectroscopy parameters of a prototypical Chagas disease drug

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Full text. Hydrogen bonds in liquids can be of crucial importance for solvent effects in spectroscopy. We have herein computed the nuclear magnetic spin-spin coupling constants (SSCC) involving 15N and 1H nuclei motivated by the relevance of these couplings for the indirect detection of the 15N chemical shifts. Such nJ(N,H) couplings are now also taken as probes for obtaining structural information in proteins. In this work, we focus on the J-couplings; a complete analysis of the NMR spectral data for the compounds studied can be found in previous papers. Thermal and solvent effects on the SSCCs of metronidazole (1) were studied computationally with appropriate quantum-chemical methods. Metronidazole may serve as a model compound to investigate the influence of solvent molecules on the NMR spin-spin coupling constants in heterocyclic rings. We find a hydrogen bond between 1 and a solvent water molecule that is associated with a bond critical point between the imidazole N-3 atom and a water H atom. AIM analysis indicates this hydrogen bond to be mainly electrostatic in nature. Simple static SSCC calculations in vacuo underestimate the nJ(N-3,H) coupling constants because of the neglect of hydrogen bonding. PCM-based treatments perform reasonably well because of the electrostatic character of the hydrogen bond. For more reliable predictions, it is important to take into account the dynamics of the system and to include nearby solvent molecules explicitly. The reduction of the hyperconjugative interactions involving the sigma CH bond or the sigma {sup *}CH antibond (with the coupling nucleus H) that is found in solution appears to be correlated to the reduction of coupling pathways in the imidazole ring. Since nuclear spin orientation information is transferred electronically to the other nuclei in the molecule, experimentally determined J-couplings directly reflect the nature of the chemical bond involved.106,107 Unlike most other NMR properties, which can be understood on the basis of semiclassical physics, J-coupling is a purely quantum- mechanical phenomenon. The present results provide evidence that hyperconjugative effects in solute molecules are not due to changes in geometric parameters upon solvation, but arise from the direct response of the electronic wave function to the presence of the solvent, which can be represented by discrete molecules and/or the dielectric bulk. We believe that our findings may be helpful to rationalize the relation between NMR parameters and the interactions in hydrogen-bonded complexes. Further applications along these lines are in progress. (author)

  1. Thermal and solvent effects on NMR spectroscopy parameters of a prototypical Chagas disease drug

    International Nuclear Information System (INIS)

    Full text. Hydrogen bonds in liquids can be of crucial importance for solvent effects in spectroscopy. We have herein computed the nuclear magnetic spin-spin coupling constants (SSCC) involving 15N and 1H nuclei motivated by the relevance of these couplings for the indirect detection of the 15N chemical shifts. Such nJ(N,H) couplings are now also taken as probes for obtaining structural information in proteins. In this work, we focus on the J-couplings; a complete analysis of the NMR spectral data for the compounds studied can be found in previous papers. Thermal and solvent effects on the SSCCs of metronidazole (1) were studied computationally with appropriate quantum-chemical methods. Metronidazole may serve as a model compound to investigate the influence of solvent molecules on the NMR spin-spin coupling constants in heterocyclic rings. We find a hydrogen bond between 1 and a solvent water molecule that is associated with a bond critical point between the imidazole N-3 atom and a water H atom. AIM analysis indicates this hydrogen bond to be mainly electrostatic in nature. Simple static SSCC calculations in vacuo underestimate the nJ(N-3,H) coupling constants because of the neglect of hydrogen bonding. PCM-based treatments perform reasonably well because of the electrostatic character of the hydrogen bond. For more reliable predictions, it is important to take into account the dynamics of the system and to include nearby solvent molecules explicitly. The reduction lvent molecules explicitly. The reduction of the hyperconjugative interactions involving the sigma CH bond or the sigma *CH antibond (with the coupling nucleus H) that is found in solution appears to be correlated to the reduction of coupling pathways in the imidazole ring. Since nuclear spin orientation information is transferred electronically to the other nuclei in the molecule, experimentally determined J-couplings directly reflect the nature of the chemical bond involved.106,107 Unlike most other NMR properties, which can be understood on the basis of semiclassical physics, J-coupling is a purely quantum- mechanical phenomenon. The present results provide evidence that hyperconjugative effects in solute molecules are not due to changes in geometric parameters upon solvation, but arise from the direct response of the electronic wave function to the presence of the solvent, which can be represented by discrete molecules and/or the dielectric bulk. We believe that our findings may be helpful to rationalize the relation between NMR parameters and the interactions in hydrogen-bonded complexes. Further applications along these lines are in progress. (author)

  2. 17O and 29Si NMR parameters of MgSiO3 phases from high-resolution solid-state NMR spectroscopy and first-principles calculations.

    Science.gov (United States)

    Ashbrook, Sharon E; Berry, Andrew J; Frost, Daniel J; Gregorovic, Alan; Pickard, Chris J; Readman, Jennifer E; Wimperis, Stephen

    2007-10-31

    The 29Si and 17O NMR parameters of six polymorphs of MgSiO3 were determined through a combination of high-resolution solid-state NMR and first-principles gauge including projector augmented wave (GIPAW) formalism calculations using periodic boundary conditions. MgSiO3 is an important component of the Earth's mantle that undergoes structural changes as a function of pressure and temperature. For the lower pressure polymorphs (ortho-, clino-, and protoenstatite), all oxygen species in the 17O high-resolution triple-quantum magic angle spinning (MAS) NMR spectra were resolved and assigned. These assignments differ from those tentatively suggested in previous work on the basis of empirical experimental correlations. The higher pressure polymorphs of MgSiO3 (majorite, akimotoite, and perovskite) are stabilized at pressures corresponding to the Earth's transition zone and lower mantle, with perovskite being the major constituent at depths >660 km. We present the first 17O NMR data for these materials and confirm previous 29Si work in the literature. The use of high-resolution multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments allows us to resolve distinct oxygen species, and full assignments are suggested. The six polymorphs exhibit a wide variety of structure types, providing an ideal opportunity to consider the variation of NMR parameters (both shielding and quadrupolar) with local structure, including changes in coordination number, local geometry (bond distances and angles), and bonding. For example, we find that, although there is a general correlation of increasing 17O chemical shift with increasing Si-O bond length, the shift observed also depends upon the exact coordination environment. PMID:17924628

  3. The effects of fast molecular motions and nuclear delocalisation on NMR parameters.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Hodgkinson, P.

    Brno : Masaryk University, 2014 - (Novotný, J.; Foroutan-Nejad, C.; Marek, R.). C3 ISBN 978-80-86441-45-0. [ NMR Valtice. Central European NMR Meeting /29./. 27.4.-30.4.2014, Valtice] Institutional support: RVO:61388963 Keywords : NMR spectroscopy * DFT molecular dynamics * nuclear quantum effects Subject RIV: CF - Physical ; Theoretical Chemistry

  4. Modeling NMR and EPR parameters in the metal-organic framework Cu3(BTC)2

    International Nuclear Information System (INIS)

    In the last decade metal-organic frameworks (MOF) have been the subject of intensive research activity due to their tunable porous structure promoting interesting properties and applications. A very powerful tool for characterization of the complex chemical and electronic structure of these nanoporous materials is magnetic resonance spectroscopy. The interpretative and analytical power of the applied NMR and EPR experimental techniques can be significantly enhanced by supplying a reliable theoretical treatment of the underlying spectroscopic parameters. We report on the application of density functional theory (DFT) for computing the magnetic resonance properties of Cu3(BTC)2(H2O)3 (BTC=benzene 1,3,5-tricarboxylate). The ADF 2008 code with Slater basis sets incorporating relativistic corrections has been used for geometry optimization of the MOF building block. We have performed gas phase calculations modeling both the ground singlet and the excited triple state of the Cu(II) ions from the paddle-wheel unit. The nuclear shielding tensors of C and H forming the BTC linkers, as well as the ESR g- and A-tensors of the Cu(II) ions in the paddle-wheel have been calculated and compared to experimental results from the literature.

  5. The effects of fast molecular motions and solvation on NMR parameters.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Bou?, Petr; Exner, T.; Hodgkinson, P.

    Santiago de Compostela : -, 2013. s. 92-93. [SMASH 2013. 22.9.2013-25.9.2013, Santiago de Compostela ] Institutional support: RVO:61388963 Keywords : NMR spectroscopy * DFT calculations * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry

  6. Relativistic many body perturbation theory: Application to spin-Hamiltonian parameters of atoms and ions with half-filled shells

    Science.gov (United States)

    Raghunathan, K.

    1980-03-01

    The relativistic ls coupling scheme is used to construct the ground state of many electron atoms, in particular, of S-state atoms with half filled shells. Some properties of the relativistic ls coupled (rls) ground state are discussed. The rls ground state is compared with that obtained from a multi-configurational approach. The suitability of the rls ground state for many body perturbation theory is discussed and it is seen to permit an appropriate adaptation of Bruckner-Goldstone perturbation expansion for relativistic theory. The high lights of our approach are: (1) the ls coupled basis of the theory permits the use of spin-orbit interaction as a perturbation even on a relativistic ground state and (2) the relativistic nature of the ground state enables the evaluation of the perturbative influence of Breit interaction on many electron wave functions. The rls formalism is tested by applying it to the quadrupole interaction in the ground state of 14 N atom. The relativistic formalism is fully exploited by evaluating the influence of Breit interaction explicitly. It is demonstrated that Breit interaction is crucial for an explanation of the experimental quadrupole interaction observed in this system.

  7. Ground-State Analysis for an Exactly Solvable Coupled-Spin Hamiltonian

    Directory of Open Access Journals (Sweden)

    Eduardo Mattei

    2013-11-01

    Full Text Available We introduce a Hamiltonian for two interacting su(2 spins. We use a mean-field analysis and exact Bethe ansatz results to investigate the ground-state properties of the system in the classical limit, defined as the limit of infinite spin (or highest weight. Complementary insights are provided through investigation of the energy gap, ground-state fidelity, and ground-state entanglement, which are numerically computed for particular parameter values. Despite the simplicity of the model, a rich array of ground-state features are uncovered. Finally, we discuss how this model may be seen as an analogue of the exactly solvable p+ip pairing Hamiltonian.

  8. Effects of Quantum Nuclear Delocalisation on NMR Parameters from Path Integral Molecular Dynamics.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Hodgkinson, P.

    2014-01-01

    Ro?. 20, ?. 8 (2014), s. 2201-2207. ISSN 0947-6539 Grant ostatní: Seventh Framework Programme of the European Union(XE) FP7-299242 People Institutional support: RVO:61388963 Keywords : density functional calculations * isotope effects * NMR spectroscopy * nuclear delocalisation * path integral molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 5.696, year: 2013

  9. The Effects of Fast Molecular Motions and Solvation on NMR Parameters.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Bou?, Petr; Exner, T.; Hodgkinson, P.

    Leipzig : European Science Foundation, 2013. s. 69-70. [CPMD - Leipzig 2013. Matter, life , light from ab initio molecular dynamics simulations. 02.09.2013-06.09.2013, Leipzig] Institutional support: RVO:61388963 Keywords : NMR spectroscopy * DFT calculations * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry

  10. The effects of fast molecular motions and nuclear delocalisation on NMR parameters.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Hodgkinson, P.

    Santiago : -, 2014. OP039. [WATOC 2014. Congress of the World Association of Theoretical and Computational Chemists /10./. 05.10.2014-10.10.2014, Santiago] R&D Projects: GA ?R GA13-24880S Institutional support: RVO:61388963 Keywords : NMR spectroscopy * molecular dynamics * DFT calculations Subject RIV: CF - Physical ; Theoretical Chemistry

  11. Microscopic spin Hamiltonian approaches for 3d8 and 3d2 ions in a trigonal crystal field - perturbation theory methods versus complete diagonalization methods

    International Nuclear Information System (INIS)

    In this paper, we critically review the existing microscopic spin Hamiltonian (MSH) approaches, namely the complete diagonalization method (CDM) and the perturbation theory method (PTM), for 3d8(3d2) ions in a trigonal (C3v, D3, D3d) symmetry crystal field (CF). A new CDM is presented and a CFA/MSH computer package based on our crystal-field analysis (CFA) package for 3dN ions is developed for numerical calculations. Our method takes into account the contribution to the SH parameters (D, gparallel and gperpendicular to) from all 45 CF states for 3d8(3d2) ions and is based on the complete diagonalization of the Hamiltonian including the electrostatic interactions, the CF terms (in the intermediate CF scheme) and the spin-orbit coupling. The CFA/MSH package enables us to study not only the CF energy levels and wavefunctions but also the SH parameters as functions of the CF parameters (B20, B40 and B43 or alternatively Dq, ? and ?') for 3d8(3d2) ions in trigonal symmetry. Extensive comparative studies of other MSH approaches are carried out using the CFA/MSH package. First, we check the accuracy of the approximate PTM based on the 'quasi-fourth-order' perturbation formulae developed by Petrosyan and Mirzakhanyan (PM). The present investigations indicate that the PM formulae for the g-factors (gparallelrmulae for the g-factors (gparallel and gperpendicular to) indeed work well, especially for the cases of small v and ?' and large Dq, whereas the PM formula for the zero-field splitting (ZFS) exhibits serious shortcomings. Earlier criticism of the PM approach by Zhou et al (Zhou K W, Zhao S B, Wu P F and Xie J K 1990 Phys. Status Solidi b 162 193) is then revisited. Second, we carry out an extensive comparison of the results of the present CFA/MSH package and those of other CDMs based on the strong- and weak-CF schemes. The CF energy levels and the SH parameters for 3d2 and 3d8 ions at C3v symmetry sites in several crystals are calculated and analysed. Our investigations reveal serious inconsistencies in the CDM results of Zhou et al and Li (Li Y 1995 J. Phys.: Condens. Matter 7 4075) based on the strong-CF scheme for Ni2+ ions in LiNbO3 crystals. The correctness of our CFA/MSH package is verified by comparing our results with the predictions of Ma et al (Ma D P, Ma N, Ma X D and Zhang H M 1998 J. Phys. Chem. Solids 59 1211, Ma D P, Ma X D, Chen J R and Liu Y Y 1997 Phys. Rev. B 56 1780) and Macfarlane (Macfarlane R M 1964 J. Chem. Phys. 40 373) for ?-Al2O3:V3+(3d2) and MgO:Ni2+(3d8). It appears that the two independent approaches show perfect agreement with our approach, unlike those of Zhou et al and Li, which turn out to be unreliable. Our results reveal that the contributions to the ZFS parameter from the higher excited states cannot be neglected; also, the ZFS parameter is very sensitive to slight changes of the crystal structure. Hence our CFA/MSH package, which takes into account the contributions to the ZFS parameter from the higher excited states, can provide reliable results and proves to be a useful tool for the studies of the effect of the lattice distortions, defects and structural disorder on the spectroscopic properties of 3d2 and 3d8 ions at trigonal symmetry sites in crystals. (author)

  12. First-principles investigation of the relation between structural and NMR parameters in vitreous GeO2

    Science.gov (United States)

    Kibalchenko, Mikhail; Yates, Jonathan R.; Pasquarello, Alfredo

    2010-04-01

    NMR parameters of 73Ge and 17O in vitreous GeO2 and quartz GeO2, including the isotropic shifts, the quadrupole coupling constants CQ, and the electric-field-gradient asymmetry parameters ?, are determined through density functional calculations. Clear correlations are established between 73Ge shifts and the mean of the four neighboring Ge-O-Ge bond angles, and between CQ and ? parameters of 17O and the local Ge-O-Ge angle. Available experimental data for CQ and the corresponding established correlation are used to extract the value of 135° for the average Ge-O-Ge angle in vitreous GeO2. The features of the Ge-O-Ge bond angle distribution of vitreous GeO2 derived in this work are consistent with those inferred from other experimental probes.

  13. Longitudinal NMR parameter measurements of Japanese pear fruit during the growing process using a mobile magnetic resonance imaging system

    Science.gov (United States)

    Geya, Yuto; Kimura, Takeshi; Fujisaki, Hirotaka; Terada, Yasuhiko; Kose, Katsumi; Haishi, Tomoyuki; Gemma, Hiroshi; Sekozawa, Yoshihiko

    2013-01-01

    Longitudinal nuclear magnetic resonance (NMR) parameter measurements of Japanese pear fruit (Pyrus pyrifolia Nakai, Kosui) were performed using an electrically mobile magnetic resonance imaging (MRI) system with a 0.2 T and 16 cm gap permanent magnet. To measure the relaxation times and apparent diffusion coefficients of the pear fruit in relation to their weight, seven pear fruits were harvested almost every week during the cell enlargement period and measured in a research orchard. To evaluate the in situ relaxation times, six pear fruits were longitudinally measured for about two months during the same period. The measurements for the harvested samples showed good agreement with the in situ measurements. From the measurements of the harvested samples, it is clear that the relaxation rates of the pear fruits linearly change with the inverse of the linear dimension of the fruits, demonstrating that the relaxation mechanism is a surface relaxation. We therefore conclude that the mobile MRI system is a useful device for measuring the NMR parameters of outdoor living plants.

  14. NMR : nuclear magnetic resonance

    International Nuclear Information System (INIS)

    This book gives description of principles of NMR for example macroscopic magnetization, devices and sample processing, NMR spectrum such as chemical shift, decoupling, interpretation of spectrum, and pulse NMR including parameters of pulse NMR. It also adds polarization transfer experiment such as SPT, INEPT, DEPT, CIDNP, 2D NMR experiment including chemical shift correlation, J-resolved experiment, indirect detection and pulsed field gradient experiment, selective excitation experiment, and NOE for instance the Solomon equations, dipolar coupling, NOE applications.

  15. Spin Hamiltonian, Competing Small Energy Scales and Incommensurate Long Range Order in the Highly Frustrated Gd3Ga5O12 Garnet Antiferromagnet

    OpenAIRE

    Yavors'kii, Taras; Enjalran, Matthew; Gingras, Michel. J. P.

    2005-01-01

    Despite the availability of a spin Hamiltonian for the Gd3Ga5O12 garnet (GGG) for over twenty five years, there has so far been little theoretical insight regarding the many unusual low temperature properties of GGG. Here we investigate GGG in zero magnetic field using mean-field theory. We reproduce the spin liquid-like correlations and, most importantly, explain the positions of the sharp peaks seen in powder neutron diffraction experiments. We show that it is crucial to t...

  16. The determination of 17O NMR parameters of hydroxyl oxygen: a combined deuteration and DOR approach.

    Science.gov (United States)

    Wong, Alan; Hung, Ivan; Howes, Andy P; Anupõld, Tiit; Past, Jaan; Samoson, Ago; Brown, Steven P; Smith, Mark E; Dupree, Ray

    2007-12-01

    The direct detection of hydroxyl oxygen (O-H) by (17)O double-rotation (DOR) NMR is very challenging because of the strong O-H dipole interaction. It is shown that deuteration of the hydroxyl site overcomes this using glycine.HCl as an illustration. Two well-separated sets of narrow (linewidth approximately 80-100 Hz) resonances with their spinning-sidebands are observed for the carboxyl and hydroxyl oxygens in the DOR spectrum of [(17)O,(2)H]glycine.HCl. The chemical shift anisotropy of these sites is obtained from a simulation of the DOR spinning-sideband intensities. The chemical shift span (Omega) for the carboxyl oxygen is found to be much larger than that of the hydroxyl oxygen, with Omega values of 540 +/- 15 and 210 +/- 10 ppm, respectively. PMID:18157798

  17. Multinuclear high-resolution NMR study of compounds from the ternary system NaF-CaF2-AlF3: from determination to modeling of NMR parameters.

    Science.gov (United States)

    Martineau, C; Body, M; Legein, C; Silly, G; Buzaré, J-Y; Fayon, F

    2006-12-11

    27Al and 23Na NMR satellite transition spectroscopy and 3Q magic-angle-spinning spectra are recorded for three compounds from the ternary NaF-CaF2-AlF3 system. The quadrupolar frequency nuQ, asymmetry parameter etaQ, and isotropic chemical shift deltaiso are extracted from the spectrum reconstructions for five aluminum and four sodium sites. The quadrupolar parameters are calculated using the LAPW-based ab initio code WIEN2k. It is necessary to perform a structure optimization of all compounds to ensure a fine agreement between experimental and calculated parameters. By a comparison of experimental and calculated values, an attribution of all of the 27Al and 23Na NMR lines to the crystallographic sites is achieved. High-speed 19F NMR MAS spectra are recorded and reconstructed for the same compounds, leading to the determination of 18 isotropic chemical shifts. The superposition model developed by Bureau et al. is used, allowing a bijective assignment of the 19F NMR lines to the crystallographic sites. PMID:17140229

  18. Diffusion parameters in single-crystalline Li3N as probed by 6Li and 7Li spin-alignment echo NMR spectroscopy in comparison with results from 8Li ?-radiation detected NMR

    International Nuclear Information System (INIS)

    6Li and 7Li two-time spin-alignment echo NMR correlation functions of single-crystalline Li3N are recorded. Around room temperature, the decay of the spin-alignment echo amplitudes is induced by slow Li jumps perpendicular to the Li2N layers. The hopping correlation functions can be best represented by a single exponential. The measured jump rates are consistent with those which were previously determined by 8Li ?-radiation detected NMR at much lower temperatures. Taking the results from 6Li and 7Li NMR as well as from 8Li ?-NMR together, between 360 and 220 K Arrhenius behaviour is found. The corresponding activation energy is 0.65(1) eV and the pre-exponential factor turned out to be 6.4(5) x 1013 s-1. Although probed from a microscopic point of view, the NMR diffusion parameters are in very good agreement with those obtained from dc-conductivity measurements, being sensitive to macroscopic transport properties. (fast track communication)

  19. The effects of some parameters on the calculated 1H NMR relaxation times of cell water

    International Nuclear Information System (INIS)

    The effect of some parameters on the longitudinal and transverse relaxation times is calculated and a comparison between the calculated relaxation times with the results of different measurements is made. (M.S.)

  20. Solid-state NMR calculations for metal oxides and gallates: Shielding and quadrupolar parameters for perovskites and related phases

    Science.gov (United States)

    Middlemiss, Derek S.; Blanc, Frédéric; Pickard, Chris J.; Grey, Clare P.

    2010-05-01

    The NMR parameters obtained from solid-state DFT calculations within the GIPAW approach for 17O- and 69/71Ga-sites in a range of predominantly oxide-based (group II monoxides, SrTiO 3, BaZrO 3, BaSnO 3, BaTiO 3, LaAlO 3, LaGaO 3, SrZrO 3, MgSiO 3 and Ba 2In 2O 5), and gallate (?- and ?-Ga 2O 3, LiGaO 2, NaGaO 2, GaPO 4 and LaGaO 3) materials are compared with experimental values, with a view to the future application of a similar approach to doped phases of interest as candidate intermediate temperature solid oxide fuel cell (ITSOFC) electrolytes. Isotropic and anisotropic chemical shift parameters, quadrupolar coupling constants, and associated asymmetries are presented and analyzed. The unusual GaO 5 site occurring in LaGaGe 2O 7 is also fully characterised. In general, it is found that the theoretical results closely track the experimental trends, though some deviations are identified and discussed, particularly in regard to quadrupolar ?Q-values. The high quality of the computed results suggests that this approach can be extended to study more complex and disordered phases.

  1. Compact NMR

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

  2. Application to ethyl-benzene of a numerical method allowing improvement of NMR spectra resolution and determination of individual component parameters

    International Nuclear Information System (INIS)

    A method for estimating parameters of exponentially damped sinusoidal transients has been applied to a NMR spectrum of ethyl-benzene. As it uses the peak derivatives rather than the classical Fourier ones, it makes them thinner and therefore allows an important resolution improvement. When such separated peaks are pure lorentzian ones, it is possible to estimate their five characteristic parameters, i.e. frequency, amplitude, damping factor, initial phase and time-delay. Gaussian peaks may be treated in the same way. (authors). 3 refs., 6 figs

  3. Possibility of using computers to estimate the correlation between the paramagnetic shifts induced by lanthanides in the NMR spectra and the structural parameters of a lanthanide-substrate system

    International Nuclear Information System (INIS)

    The present work examines the possibility of using computers to estimate the correlation between the paramagnetic shifts induced by lanthanides in the NMR spectra abnd the structural parameters of a lanthanide-substrate system

  4. Spectral assignments and NMR parameter-structure relationships in borates using high-resolution 11B NMR and density functional theory.

    Science.gov (United States)

    Alderman, Oliver L G; Iuga, Dinu; Howes, Andrew P; Pike, Kevin J; Holland, Diane; Dupree, Ray

    2013-06-01

    High-resolution, solid-state (11)B NMR spectra have been obtained at high magnetic fields for a range of polycrystalline borates using double-rotation (DOR), multiple-quantum magic angle spinning and isotopic dilution. DOR linewidths can be less than 0.2 ppm in isotopically diluted samples, allowing highly accurate values for the isotropic chemical shift, ?iso, and electric field gradient to be obtained. The experimental values are used as a test of density functional calculations using both projector augmented wave based CASTEP and WIEN2k. The CASTEP calculations of ?iso are generally in very good agreement with experiment, having r.m.s. deviation 0.40 ppm. WIEN2k calculations of electric field gradient magnitude, CQ, and asymmetry, ?, are also in excellent agreement with experiment, with r.m.s. deviations 0.038 MHz and 0.042 respectively. However, whilst CASTEP gives a similar deviation for ? (0.043) it overestimates CQ by ?15%. After scaling of the calculated electric field gradient by 0.842 the deviation in CQ is practically identical to that of the WIEN2k calculations. The spectral assignments that follow from the experimental and computational results allow identification of correlations between ?iso and (a) the average B-O-B bond angle, ?[combining overline], for both three and four coordinated boron, giving ?iso(B(III)) = (185.1 -?[combining overline])/3.42 ppm and ?iso(B(IV)) = (130.2 -?[combining overline])/5.31 ppm; and (b) the ring-site T(3) unit trigonal planar angular deviation, Stri, giving ?iso(T(3)(ring)) = (1.642 × 10(-2)-Stri)/(8.339 × 10(-4)) ppm. PMID:23608768

  5. A molecular dynamics study of the effects of fast molecular motions on solid-state NMR parameters.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Hodgkinson, P.

    2013-01-01

    Ro?. 15, ?. 43 (2013), s. 8705-8712. ISSN 1466-8033 Grant ostatní: Seventh Framework Programme of the European Union(XE) FP7-299242 People Institutional support: RVO:61388963 Keywords : molecular dynamics * DFT calculations * NMR spectroscopy Subject RIV: CC - Organic Chemistry Impact factor: 3.858, year: 2013

  6. Temperature dependence of contact and dipolar NMR chemical shifts in paramagnetic molecules

    Science.gov (United States)

    Martin, Bob; Autschbach, Jochen

    2015-02-01

    Using a recently proposed equation for NMR nuclear magnetic shielding for molecules with unpaired electrons [A. Soncini and W. Van den Heuvel, J. Chem. Phys. 138, 021103 (2013)], equations for the temperature (T) dependent isotropic shielding for multiplets with an effective spin S equal to 1/2, 1, 3/2, 2, and 5/2 in terms of electron paramagnetic resonance spin Hamiltonian parameters are derived and then expanded in powers of 1/T. One simplifying assumption used is that a matrix derived from the zero-field splitting (ZFS) tensor and the Zeeman coupling matrix (g-tensor) share the same principal axis system. The influence of the rhombic ZFS parameter E is only investigated for S = 1. Expressions for paramagnetic contact shielding (from the isotropic part of the hyperfine coupling matrix) and pseudo-contact or dipolar shielding (from the anisotropic part of the hyperfine coupling matrix) are considered separately. The leading order is always 1/T. A temperature dependence of the contact shielding as 1/T and of the dipolar shielding as 1/T2, which is sometimes assumed in the assignment of paramagnetic chemical shifts, is shown to arise only if S ? 1 and zero-field splitting is appreciable, and only if the Zeeman coupling matrix is nearly isotropic (?g = 0). In such situations, an assignment of contact versus dipolar shifts may be possible based only on linear and quadratic fits of measured variable-temperature chemical shifts versus 1/T. Numerical data are provided for nickelocene (S = 1). Even under the assumption of ?g = 0, a different leading order of contact and dipolar shifts in powers of 1/T is not obtained for S = 3/2. When ?g is not very small, dipolar and contact shifts both depend in leading order in 1/T in all cases, with sizable contributions in order 1/Tn with n = 2 and higher.

  7. NMR Spectroscopy

    Science.gov (United States)

    Reich, Ieva

    Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. These questions pertain to Nuclear magnetic resonance (NMR) spectroscopy and include topics such as: Chemical Shift, Proton NMR, and Carbon NMR.

  8. Theoretical investigations of spin Hamilton parameters and Knight shifts for rhombic and tetragonal CuGeO3

    International Nuclear Information System (INIS)

    The spin Hamiltonian parameters (g factors and hyperfine structure constants) and the Knight shifts for Cu2+ in the spin-Pierels compound CuGeO3 of rhombic and tetragonal phases are theoretically investigated from the high order perturbation formulas of these parameters for a 3d9 ion under rhombically and tetragonally elongated octahedra in a uniform way. The approximately linear relationships between Knight shifts and g factors are found, i.e., Ki/(gi?gs)=Kj/(gj?gs) (with i, j=x, y and z; gs?2.0023). The theoretical results show good agreement with the observed values, and the improvements are achieved by adopting the fewer adjustable parameters as compared with the previous treatments. The anisotropies of the g factors and the Knight shifts are attributed to the local rhombic and tetragonal elongations of the Cu2+ sites. The studies in this work would be helpful to establish complete physical scheme for uniform investigations on EPR and NMR spectroscopic behaviours of Cu2+ (or other similar 3d9 ions) in compounds

  9. 1H NMR z-spectra of acetate methyl in stretched hydrogels: Quantum-mechanical description and Markov chain Monte Carlo relaxation-parameter estimation

    Science.gov (United States)

    Shishmarev, Dmitry; Chapman, Bogdan E.; Naumann, Christoph; Mamone, Salvatore; Kuchel, Philip W.

    2015-01-01

    The 1H NMR signal of the methyl group of sodium acetate is shown to be a triplet in the anisotropic environment of stretched gelatin gel. The multiplet structure of the signal is due to the intra-methyl residual dipolar couplings. The relaxation properties of the spin system were probed by recording steady-state irradiation envelopes ('z-spectra'). A quantum-mechanical model based on irreducible spherical tensors formed by the three magnetically equivalent spins of the methyl group was used to simulate and fit experimental z-spectra. The multiple parameter values of the relaxation model were estimated by using a Bayesian-based Markov chain Monte Carlo algorithm.

  10. Dft Study on 4(5-Imidazole-Carbaldehyde-N(5-Phenylthiosemicarbazone (Imtph: Nmr Shielding Tensors, Thermodynamic Parameters, Nbo Analysis, Molecular Electrostatic Potential (Mep, Homo and Lumo Studies

    Directory of Open Access Journals (Sweden)

    Masoome Sheikhi

    2014-03-01

    Full Text Available The density functional theory (DFT calculations at the level of B3LYP/6-31G was carried out on the structure 4(5-Imidazole-carbaldehyde-N(5-phenylthiosemicarbazone (ImTPh in gas phase using Gaussian 03. Dipole moment (Debye, energy of structure formation (HF; kcal/mol and point group, NMR parameters such as isotropic shielding (?iso and anisotropic shielding (?aniso, ?11, ?22 and ?33 obtained. Also thermodynamic properties and natural bond orbitals (NBO were calculated. Besides, the frontier molecular orbital (FMO analysis and the molecular electrostatic potential (MEP of the compound were investigated by theoretical calculations.

  11. DFT study of molecular structures and 13C NMR parameters of two fluorinated biphenyls and their ?6-tricarbonylchromium complexes

    Science.gov (United States)

    Gryff-Keller, Adam; Szczeci?ski, Przemys?aw

    2015-07-01

    The molecular structures of 2,2?-difluoro-6,6?-dimethylbiphenyl, 4,5-difluoro-9,10-dihydrophenanthrene and of their ?6-tricarbonylchromium complexes have been discussed in the light of the results of molecular energy calculations. Also the isotropic magnetic shielding constants and carbon-fluorine spin-spin coupling constants for these objects have been calculated and compared with the experimental values of 13C NMR chemical shifts and J constants. The calculational methods used were: DFT/BHandH/6-311++G(2d,p) and/or DFT/B3LYP/6-311++G(2d,p). It has been confirmed that experimental 13C NMR chemical shifts for ?6-arene tricarbonylchromium complexes can be satisfactorily predicted using both methods, although the method exploiting BHandH functional is not able to reproduce the 13C NMR chemical shifts of Cr(CO)3 carbon atoms. On the other hand, this method provides the J(13C, 19F) values which are close to the experimental ones.

  12. Study of correlations in molecular motion by multiple quantum NMR

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance is a very useful tool for characterizing molecular configurations through the measurement of transition frequencies and dipolar couplings. The measurement of spectral lineshapes, spin-lattice relaxation times, and transverse relaxation times also provide us with valuable information about correlations in molecular motion. The new technique of multiple quantum nuclear magnetic resonance has numerous advantages over the conventional single quantum NMR techniques in obtaining information about static and dynamic interactions of coupled spin systems. In the first two chapters, the theoretical background of spin Hamiltonians and the density matrix formalism of multiple quantum NMR is discussed. The creation and detection of multiple quantum coherence by multiple pulse sequence are discussed. Prototype multiple quantum spectra of oriented benzene are presented. Redfield relaxation theory and the application of multiple quantum NMR to the study of correlations in fluctuations are presented. A specific example of an oriented methyl group relaxed by paramagnetic impurities is studied in detail. The study of possible correlated motion between two coupled methyl groups by multiple quantum NMR is presented. For a six spin system it is shown that the four-quantum spectrum is sensitive to two-body correlations, and serves a ready test of correlated motion. The study of the spin-lattice dynamics of orienting or tunneling methyl groups (CH3 and CD3) at low temperatures is presented. The anisotropic spin-lattice relaxation of deuterated hexamethylbenzene, caused by the sixfold reorientation of the molecules, is investigated, and the NMR spectrometers and other experimental details are discussed

  13. Optimisation of NMR dynamic models II. A new methodology for the dual optimisation of the model-free parameters and the Brownian rotational diffusion tensor

    International Nuclear Information System (INIS)

    Finding the dynamics of an entire macromolecule is a complex problem as the model-free parameter values are intricately linked to the Brownian rotational diffusion of the molecule, mathematically through the autocorrelation function of the motion and statistically through model selection. The solution to this problem was formulated using set theory as an element of the universal set U-the union of all model-free spaces (d'Auvergne EJ and Gooley PR (2007) Mol BioSyst 3(7), 483-494). The current procedure commonly used to find the universal solution is to initially estimate the diffusion tensor parameters, to optimise the model-free parameters of numerous models, and then to choose the best model via model selection. The global model is then optimised and the procedure repeated until convergence. In this paper a new methodology is presented which takes a different approach to this diffusion seeded model-free paradigm. Rather than starting with the diffusion tensor this iterative protocol begins by optimising the model-free parameters in the absence of any global model parameters, selecting between all the model-free models, and finally optimising the diffusion tensor. The new model-free optimisation protocol will be validated using synthetic data from Schurr JM et al. (1994) J Magn Reson B 105(3), 211-224 and the relaxation data of the bacteriorhodopsin (1-36)BR fragment from Orekhov VY (1999) J Biomol NMR 14(4), 345-356. To demonstrate the importance of this new procedonstrate the importance of this new procedure the NMR relaxation data of the Olfactory Marker Protein (OMP) of Gitti R et al. (2005) Biochem 44(28), 9673-9679 is reanalysed. The result is that the dynamics for certain secondary structural elements is very different from those originally reported

  14. Molecular modeling and experimental studies on structure and NMR parameters of 9-benzyl-3,6-diiodo-9H-carbazole

    DEFF Research Database (Denmark)

    Radula-Janik, Klaudia; Kupka, Teobald

    2015-01-01

    A combined experimental and theoretical study has been performed on 9-benzyl-3,6-diiodo-9H-carbazole. Experimental X-ray (100.0 K) and room-temperature 13C NMR studies were supported by advanced density functional theory (DFT) calculations. The non relativistic structure optimization was performed and the 13C nuclear magnetic shieldings were predicted at the relativistic level of theory using the Zeroth Order Regular Approximation (ZORA). The changes in the benzene and pyrrole rings compared to the unsubstituted carbazole or the parent molecules were discussed in terms of aromaticity changes using the harmonic oscillator model of aromaticity (HOMA) and the nucleus independent chemical shift (NICS) indexes. Theoretical relativistic calculations of chemical shifts of carbons C3 and C6, directly bonded to iodine atoms, produced a reasonable agreement with experiment (initial deviation from experiment of 41.57 ppm dropped to 5.6 ppm). A good linear correlation between experimental and theoretically predicted structural and NMR parameters was observed.

  15. (1)H NMR z-spectra of acetate methyl in stretched hydrogels: quantum-mechanical description and Markov chain Monte Carlo relaxation-parameter estimation.

    Science.gov (United States)

    Shishmarev, Dmitry; Chapman, Bogdan E; Naumann, Christoph; Mamone, Salvatore; Kuchel, Philip W

    2015-01-01

    The (1)H NMR signal of the methyl group of sodium acetate is shown to be a triplet in the anisotropic environment of stretched gelatin gel. The multiplet structure of the signal is due to the intra-methyl residual dipolar couplings. The relaxation properties of the spin system were probed by recording steady-state irradiation envelopes ('z-spectra'). A quantum-mechanical model based on irreducible spherical tensors formed by the three magnetically equivalent spins of the methyl group was used to simulate and fit experimental z-spectra. The multiple parameter values of the relaxation model were estimated by using a Bayesian-based Markov chain Monte Carlo algorithm. PMID:25486634

  16. Conformational stability, vibrational and NMR analysis, chemical potential and thermodynamical parameter of 3-tert-butyl-4-hydroxyanisole

    Science.gov (United States)

    Balachandran, V.; Karpagam, V.; Revathi, B.; Kavimani, M.; Santhi, G.

    2015-01-01

    The FT-IR and FT-Raman spectra of 3-tert-butyl-4-hydroxyanisole (TBHA) molecule have been recorded in the region 4000-400 cm-1 and 3500-100 cm-1, respectively. Optimized geometrical structure, harmonic vibrational frequencies has been computed by B3LYP level using 6-31G (d, p) and 6-311 + G (d, p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The Mulliken charges, the natural bonding orbital (NBO) analysis, the first-order hyperpolarizability of the investigated molecule were computed using DFT calculations. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and analyzed. The isotropic chemical shift computed by 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the TBHA calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations.

  17. Exact NMR simulation of protein-size spin systems using tensor train formalism

    Science.gov (United States)

    Savostyanov, D. V.; Dolgov, S. V.; Werner, J. M.; Kuprov, Ilya

    2014-08-01

    We introduce a new method, based on alternating optimization, for compact representation of spin Hamiltonians and solution of linear systems of algebraic equations in the tensor train format. We demonstrate the method's utility by simulating, without approximations, a N15 NMR spectrum of ubiquitin—a protein containing several hundred interacting nuclear spins. Existing simulation algorithms for the spin system and the NMR experiment in question either require significant approximations or scale exponentially with the spin system size. We compare the proposed method to the Spinach package that uses heuristic restricted state space techniques to achieve polynomial complexity scaling. When the spin system topology is close to a linear chain (e.g., for the backbone of a protein), the tensor train representation is more compact and can be computed faster than the sparse representation using restricted state spaces.

  18. Exact NMR simulation of protein-size spin systems using tensor train formalism

    CERN Document Server

    Savostyanov, D V; Werner, J M; Kuprov, Ilya

    2014-01-01

    We introduce a new method, based on alternating optimization, for compact representation of spin Hamiltonian, and solution of linear systems in the tensor train format. We demonstrate its utility by simulating, without significant approximations, a 15N NMR spectrum of ubiquitin --- protein containing several hundred interacting nuclear spins. Existing simulation algorithms for the spin system and the NMR experiment in question either require significant approximations or scale exponentially with the system size. We compare the proposed method to the Spinach package that uses heuristic restricted state space (RSS) techniques to achieve polynomial complexity scaling. When the spin system topology is close to a linear chain (e.g. for backbone of a protein), the tensor train representation of a Hamiltonian is more compact and can be computed faster than the sparse representation using the RSS.

  19. Theoretical studies of EPR parameters of spin-labels incomplex environments

    OpenAIRE

    Frecus, Bogdan

    2013-01-01

    This thesis encloses quantum chemical calculations performed in the framework of density functional response theory for evaluating electron paramagnetic resonance (EPR) spin Hamiltonian parameters of various spin-labels in different environments. These parameters are the well known electronic g-tensor and the nitrogen hyperfine coupling constants, which are extensively explored in this work for various systems. A special attention was devoted to the relationships that form between the structu...

  20. Benford distributions in NMR

    CERN Document Server

    Bhole, Gaurav; Mahesh, T S

    2014-01-01

    Benford's Law is an empirical law which predicts the frequency of significant digits in databases corresponding to various phenomena, natural or artificial. Although counter intuitive at the first sight, it predicts a higher occurrence of digit 1, and decreasing occurrences to other larger digits. Here we report the Benford analysis of various NMR databases and draw several interesting inferences. We observe that, in general, NMR signals follow Benford distribution in time-domain as well as in frequency domain. Our survey included NMR signals of various nuclear species in a wide variety of molecules in different phases, namely liquid, liquid-crystalline, and solid. We also studied the dependence of Benford distribution on NMR parameters such as signal to noise ratio, number of scans, pulse angles, and apodization. In this process we also find that, under certain circumstances, the Benford analysis can distinguish a genuine spectrum from a visually identical simulated spectrum. Further we find that chemical-sh...

  1. ? –stacking effects on the EPR parameters of a prototypical DNA spin label

    OpenAIRE

    Frecus, Bogdan; Rinkevicius, Zilvinas; Ågren, Hans

    2013-01-01

    The character and value of spin labels for probing environments like double-stranded DNA depends on the degree of changeof the spin Hamiltonian parameters of the spin label induced by the environment. Herein we provide a systematic theoreticalinvestigation of this issue, based on a density functional theory method applied to a spin labeled DNA model system, focusingon the dependence of the EPR properties of the spin label on the ? stacking and hydrogen bonding that occur upon incorporatingth...

  2. Spin-spin cross relaxation and spin-Hamiltonian spectroscopy by optical pumping of Pr/sup 3+/:LaF3

    International Nuclear Information System (INIS)

    We report the observation of an anticrossing in solid-state laser spectroscopy produced by cross relaxation. Spin-spin cross relaxation between the /sup 141/Pr- and /sup 19/F-spin reservoirs in Pr/sup 3+/:LaF3 and its influence on the /sup 141/Pr NMR spectrum is detected by means of optical pumping. The technique employed combines optical pumping and hole burning with either external magnetic field sweep or rf resonance saturation in order to produce slow transient changes in resonant laser transmission. At a certain value of the external Zeeman field, where the energy-level splittings of Pr and F spins match, a level repulsion and discontinuity of the Pr/sup 3+/ NMR lines is observed. This effect is interpreted as the ''anticrossing'' of the combined Pr-F spin-spin reservoir energy states. The Zeeman-quadrupole-Hamiltonian spectrum of the hyperfine optical ground states of Pr/sup 3+/:LaF3 is mapped out over a wide range of Zeeman magnetic fields. A new scheme is proposed for dynamic polarization of nuclei by means of optical pumping, based on resonant cross relaxation between rare spins and spin reservoirs

  3. Quantitative NMR

    Science.gov (United States)

    Korir, Albert K.

    This site features a learning module focused on principles and practice of NMR for quantitative analysis, an application less commonly associated with the technique than is structure determination. Links to simulation packages are included.

  4. NMR Animations

    Science.gov (United States)

    This site features animated tutorials on NMR with sufficient depth to be useful to the non NMR savvy. The animations are accompanied by short descriptions so that the processes displayed can be understood by the viewer. This site goes beyond just showing precession. There are nice animations showing the effect of different pulses, including composite pulses on the magnetization, the effects of magnetic gradient pulses to measure diffusion and do coherence pathway selection.

  5. NMR tutorial

    Science.gov (United States)

    Bogdal, Dariusz

    This site provides an entry-level introduction to NMR in a text and figures format. The site also contains example structure elucidation problems using NMR, IR and MS data complete with hints and answers. Although the molecules included are somewhat simple, the examples do a good job of illustrating the structure elucidation process. The site also has data for several more complex structure determination problems.

  6. NMR analysis of proteins structure

    International Nuclear Information System (INIS)

    The nuclear magnetic resonance (NMR) analysis of proteins aims at determining the 3-D folding of the polypeptide chain. Because of the high number of nuclei observed in the samples, the NMR protein spectra are extremely complex. The different steps of the structure determination are: the preparation of the samples, the acquisition and processing of the NMR signal, the analysis and attribution of spectra, and the calculation of the coordinates of the atoms using the NMR spectra parameters. Content: 1 - proteins and peptides (composition and structure, secondary, tertiary and quaternary structure); 2 - NMR of proteins in solution (characteristics, structures determination, homonuclear experiments, heteronuclear experiments, proteins with a size higher than 20 kDa, intermolecular interactions, stability factors, internal molecular dynamics); 3 - structures calculation (calculation framework, distance geometry, molecular dynamics and simulated annealing, quality of the structure obtained). (J.S.)

  7. Analysis of the temperature and pressure dependence of the 129Xe NMR chemical shift and signal intensity for the derivation of basic parameters of adsorption as applied to zeolite ZSM-5.

    Science.gov (United States)

    Kawata, Yoko; Adachi, Yuko; Haga, Saori; Fukutomi, Junko; Imai, Hirohiko; Kimura, Atsuomi; Fujiwara, Hideaki

    2007-12-01

    Temperature and pressure dependences of the 129Xe NMR chemical shift and the signal intensity have been investigated using ZSM-5 as an adsorbent under routine conditions without using any high-pressure or especially high-temperature facilities. The use of a rigorously shielded system and a calibration sample for the signal intensity was found to be valuable to obtain reliable data about the chemical shift and the signal intensity. The 129Xe NMR data obtained between 0.05 and 1.5 atm and from 24 to 80 degrees C were analyzed based on the Dubinin-Radushkevich equation as well as the Langmuir type equation. In both analyses, chemical shift data succeeded only partially in providing the profile of adsorption, such as energetic aspects, surface area, saturated amount of Xe adsorption and specific parameters of 129Xe chemical shift. It was shown that the reliable total analysis was achieved when the chemical shift data were used together with the intensity data. Such an analysis of the chemical shift data, aided by the intensity data, will be useful in performing nano-material analysis on 129Xe NMR without invoking the traditional methodology of gravimetric or volumetric adsorption experiments. PMID:18071225

  8. The automatic NMR gaussmeter

    International Nuclear Information System (INIS)

    The paper describes the automatic gaussmeter operating according to the principle of nuclear magnetic resonance. There have been discussed the operating principle, the block diagram and operating parameters of the meter. It can be applied to measurements of induction in electromagnets of wide-line radio-spectrometers EPR and NMR and in calibration stands of magnetic induction values. Frequency range of an autodyne oscillator from 0,6 up to 86 MHz for protons is corresponding to the field range from 0.016 up to 2T. Applicaton of other nuclei, such as 7Li and 2D is also foreseen. The induction measurement is carried over automatically, and the NMR signal and value of measured induction are displayed on a monitor screen. (author)

  9. NMR espectroscopic parameters of HX and Si (Sn)X{sub 4} (X = H, F, Cl, Br and I) and SnBr{sub 4-n}I{sub n} model compounds

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado, Alejandro F.; Gimenez, Carlos A. [Physics Department, Natural and Exact Science Faculty, Northeastern University of Argentina and Institute of Modelling and Innovation on Technology, IMIT Avda Libertad 5460, W3404AAS Corrientes (Argentina); Aucar, Gustavo A., E-mail: gaa@unne.edu.ar [Physics Department, Natural and Exact Science Faculty, Northeastern University of Argentina and Institute of Modelling and Innovation on Technology, IMIT Avda Libertad 5460, W3404AAS Corrientes (Argentina)

    2012-02-20

    Graphical abstract: Optimized fully relativistic calculations of NMR J-couplings (HBr, HI), chemical shifts (Si, Sn) and absolute shielding for reference compounds of heavy atoms (Si, Sn) are given. Highlights: Black-Right-Pointing-Pointer In this article we show a procedure to get accurate NMR {sigma}{sup Ref} of Si and Sn. Black-Right-Pointing-Pointer Calculations of {sigma} on more than three heavy-atom-containing molecules are given. Black-Right-Pointing-Pointer Our results are closer to {delta}{sup exp} than previous calculations for SnX{sub 4} (X = H, Cl, Br, I). Black-Right-Pointing-Pointer Optimized basis sets were considered for full R and NR calculations of NMR J and {sigma}. Black-Right-Pointing-Pointer Relativistic effects enlarge electron correlation effects on J-couplings. - Abstract: The NMR spectroscopic parameters are largely influenced by relativistic effects. They are highly dependent on the electronic behavior inside the spatial regions occupied by nuclei. Full relativistic calculations of indirect nuclear spin-spin couplings at random phase level of approach (RPA) in the title compounds with reoptimized Dyall cVTZ basis sets are given. A comparison with the results of calculations with other basis sets that are mostly used within the non-relativistic (NR) domain is presented. We analyzed the dependence of that couplings with the speed of light over the whole range of values, from the full relativistic to the NR regimes. Within this last regime, calculations at the second-order level of approach (SOPPA) indicated that electron correlation effects may not be as important for nuclear magnetic shieldings, but they must be included with care for J-coupling calculations. From these calculations, we determined that relativity enlarges the electron correlation effects of the J-couplings of HBr and HI. Because the results of nuclear magnetic shielding calculations within polarization propagators at the RPA level were reliable, we were able to show a new and easy procedure to obtain absolute nuclear magnetic shieldings on reference compounds for both Si and Sn nuclei: {sigma}[Si (CH{sub 3}){sub 4}] = 421.28 {+-} 29.33 ppm and {sigma}[Sn (CH{sub 3}){sub 4}] = 3814.96 {+-} 79.12 ppm. They were obtained from experimental chemical shifts and accurate nuclear magnetic shielding calculations on different molecular systems.

  10. NMR imaging of the eye, orbita, and optic nerve

    International Nuclear Information System (INIS)

    Starting from an introduction into the physico-technical bases of NMR imaging, the book gives an overview of characteristic NMR findings for the most important diseases of the eye, orbita, and optic nerve, attributing special importance to the choice of suitable diagnostical parameters and instructive image material. The rank of NMR imaging as compared to other imaging techniques is discussed; guidelines for employing NMR imaging in ophthalmology conclude the book. (orig.) With 352 figs., 7 tabs

  11. Mechanical analogues of spin Hamiltonians and dynamics

    International Nuclear Information System (INIS)

    Bloch et al. mapped the precession of the spin-half in a magnetic field of variable magnitude and direction to the rotations of a rigid sphere rolling on a curved surface utilizing SU(2)–SO(3) isomorphism. This formalism is extended to study the behaviour of spin–orbit interactions and the mechanical analogy for Rashba–Dresselhauss spin–orbit interaction in two dimensions is presented by making its spin states isomorphic to the rotations of a rigid sphere rolling on a ring. The change in phase of spin is represented by the angle of rotation of sphere after a complete revolution. In order to develop the mechanical analogy for the spin filter, we find that perfect spin filtration of down spin makes the sphere to rotate at some unique angles and the perfect spin filtration of up spin causes the rotations with certain discrete frequencies.

  12. Gravitational spin Hamiltonians from the S matrix

    OpenAIRE

    Vaidya, Varun

    2014-01-01

    We utilize generalized unitarity and recursion relations combined with effective field theory(EFT) techniques to compute spin dependent interaction terms for inspiralling binary systems in the post newtonian(PN) approximation. Using these methods offers great computational advantage over traditional techniques involving feynman diagrams, especially at higher orders in the PN expansion. As a specific example, we reproduce the spin-orbit interaction up to 2.5 PN order as also ...

  13. First-principles calculations of finite temperature Sc and O NMR parameters in Pb(Sc2/3W1/3)O3

    Science.gov (United States)

    Krakauer, Henry; Walter, Eric J.; Ellden, Jeremy; Hoatson, Gina L.; Vold, Robert L.

    2012-02-01

    Understanding the dynamics of complex relaxor ferroelectrics is important to characterizing their large electromechanical coupling. Preliminary NMR measurements of Sc electric-field-gradients (EFG) in Pb(Sc2/3W1/3)O3 (PSW) show a strong temperature dependence in the range T = 250 - 330 K. To understand this behavior, we use the first-principles GIPAWootnotetextC. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001); method within the Quantum Espresso (QE) packageootnotetextP. Giannozzi et al., Journal of Physics: Condensed Matter 21, 395502 (2009) to calculate ^45Sc and ^17O chemical-shifts and EFG tensors. To study finite temperature effects, we incorporate the thermal expansion of the lattice and sample thermal disorder, using the phonon degrees of freedom. As in our previous studies of perovksites,ootnotetextD. L. Pechkis, E. J. Walter, and H. Krakauer. J. Chem. Phys. 135, 114507 (2011); ibid. 131, 184511 (2009) we show that the ^17O chemical shifts in PSW also exhibit a linear correlation with the nearest-neighbor B-O bond length.

  14. Minimalist Relativistic Force Field: Prediction of Proton-Proton Coupling Constants in (1)H NMR Spectra Is Perfected with NBO Hybridization Parameters.

    Science.gov (United States)

    Kutateladze, Andrei G; Mukhina, Olga A

    2015-05-15

    We previously developed a reliable method for multiparametric scaling of Fermi contacts to achieve fast and accurate prediction of proton-proton spin-spin coupling constants (SSCC) in (1)H NMR. We now report that utilization of NBO hybridization coefficients for carbon atoms in the involved C-H bonds allows for a significant simplification of this parametric scheme, requiring only four general types of SSCCs: geminal, vicinal, 1,3-, and long-range constants. The method is optimized for inexpensive B3LYP/6-31G(d) molecular geometries. A new DU8 basis set, based on a training set of 475 experimental spin-spin coupling constants, is developed for hydrogen and common non-hydrogen atoms (Li, B, C, N, O, F, Si, P, S, Cl, Se, Br, I) to calculate Fermi contacts. On a test set of 919 SSCCs from a diverse collection of natural products and complex synthetic molecules the method gave excellent accuracy of 0.29 Hz (rmsd) with the maximum unsigned error not exceeding 1 Hz. PMID:25885091

  15. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1992-01-01

    The protean nature of the applications of NMR is regularly reflected in Annual Reports on NMR Spectroscopy. Volume 24 is no exception, and it is an ineluctable fact that all areas of science appear to benefit upon submission to the blandishments of NMR. The examples provided here encompass solid state NMR, solid state NMR imaging, NMR studies of interfaces, NMR investigations of cells and organisms, 199 Mercury NMR, and some applications of NMR to the area of coal science.

  16. Fundamentals of NMR

    Science.gov (United States)

    James, Thomas L.

    This e-text presents an introduction to the fundamentals of NMR covering magnetic resonance, pulsed NMR, relaxation, chemical shift, spin-spin coupling, the nuclear Overhauser effect and chemical exchange. The document may be downloaded in PDF format.

  17. NMR analysis of biodiesel

    Science.gov (United States)

    Biodiesel is usually analyzed by the various methods called for in standards such as ASTM D6751 and EN 14214. Nuclear magnetic resonance (NMR) is not one of these methods. However, NMR, with 1H-NMR commonly applied, can be useful in a variety of applications related to biodiesel. These include monit...

  18. Application of the NMR-MOUSE to food emulsions

    Science.gov (United States)

    Pedersen, H. T.; Ablett, S.; Martin, D. R.; Mallett, M. J. D.; Engelsen, S. B.

    2003-11-01

    The application of the NMR-MObile Universal Surface Explorer (NMR-MOUSE) to study food systems is evaluated using oil-in-water emulsions, and the results are compared to those obtained using a conventional low-field NMR (LF-NMR) instrument. The NMR-MOUSE is a small and portable LF-NMR system with a one-sided magnet layout that is used to replace the conventional magnet and probe on a LF-NMR instrument. The high magnetic field gradients associated with the one-sided MOUSE magnet result in NMR signal decays being dominated by molecular diffusion effects, which makes it possible to discriminate between the NMR signals from oil and water. Different data acquisition parameters as well as different approaches to the analysis of the NMR data from a range of oil-in-water emulsions are evaluated, and it is demonstrated how the concentration of oil and water can be determined from the NMR-MOUSE signals. From these model systems it is concluded that the NMR-MOUSE has good potential for the quantitative analysis of intact food products.

  19. NMR studies of multiphase flows II

    Energy Technology Data Exchange (ETDEWEB)

    Altobelli, S.A.; Caprihan, A.; Fukushima, E. [Lovelace Institutes, Albuquerque, NM (United States)] [and others

    1995-12-31

    NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

  20. 11B NMR spectroscopy

    International Nuclear Information System (INIS)

    This paper covers developments in 11B NMR spectroscopy subsequent to a previous review in this series. In addition, it serves to complement the preceding chapter. As in previous years, a major use of 11B has been archival - that is, use for routine characterization of new compounds - although considerable efforts to elucidate correlations between structure and NMR parameters continue. However, some significant trends may be noted. First, availability of high-field spectrometers with multinuclear capability as well as software for sophisticated data manipulation is increasingly common, and, with these instruments, lack of chemical-shift dispersion in the face of relatively large linewidths presents much less of a problem than previously when complex polyboron compounds are to be characterized. Coupled with this, potent separation techniques, exemplified by thin-layer, high-pressure and ion-exchange chromatography, are able to unravel complex mixtures and make pure compounds available for study. Use of X-ray crystallographic facilities with which to structurally characterize compounds whose spectra are reported is today almost routine. Less routine is an appreciation of the fact that one crystal teased from a reaction mixture is not necessarily representative of the system from which it was extracted; use of X-ray powder-diffraction analysis to test this hypothesis is to be encouraged. Thus inability to separate mixtures, to secure high-resolution arate mixtures, to secure high-resolution spectra and structural data are of decreasing importance in boron chemistry, leaving, perhaps, as the rate-limiting factors, creativity and the propensity to select for detailed study systems that offer new, significant and fundamental insights into the chemistry of boron and of the elements to which it bonds

  1. NMR-spectroscopy

    International Nuclear Information System (INIS)

    Physical foundations are given and the most important areas of nuclear magnetic resonance (NMR) application in physics, chemistry, biology are described. A detailed review of the investigations conducted and the NMR applications in different science and technology fields is presented. The method basic experimental variants, including such new ones as high resolution in a solid body; rare isotope resonance; two-dimensional and multi-quantum fourier-spectroscopy; large molecule NMR; NMR tomography and NMR intrascopy etc. are considered. The instruments are briefly described. NMR is characterized as one of the most important investigation methods of the material composition, its molecular and crystal structure, visualization of the living organism and nonmetallic object inner structure

  2. Materials mapped with NMR

    International Nuclear Information System (INIS)

    This article describes the use of nuclear magnetic resonance (NMR) imaging as a non-invasive nondestructive inspection technique for a variety of industrial material applications. NMR relaxation, determined by the lifetime of a nucleus in a given excited state, is used as a clinical contrast mechanism. Hardware for high-resolution industrial NMR imaging still needs to be developed as, to date, it has been chiefly used for medical diagnosis. Techniques used at present are described and future trends suggested. (UK)

  3. Small NMR biomolecular sensors

    Science.gov (United States)

    Sun, Nan; Liu, Yong; Qin, Ling; Lee, Hakho; Weissleder, Ralph; Ham, Donhee

    2013-06-01

    By combining the physics of nuclear magnetic resonance (NMR) and silicon radio-frequency (RF) integrated circuits, we recently created progressively smaller NMR systems, which we originally reported in Refs. [1-4]. Our strategy for NMR system miniaturization proved effective, culminating in the smallest prototype [3,4] that weighs 0.1 kg and can be held at the palm of the hand. These small, low-cost NMR systems can be useful as biomolecular sensors in the personalized medicine setting, and we demonstrated their ability to detect proteins, compounds, and human cancer cells. The present paper, which is not a new technical contribution, reviews these developments.

  4. Understanding NMR Spectroscopy

    Science.gov (United States)

    Keeler, James

    This site provides links to a series of PDF files that represent chapters of an e-text on the basics of NMR. While many other textbooks on NMR are available, the chief merit of this one is that it has a nice chapter on the NMR instrumentation (ch. 5) which should be accessible to undergraduates. The text also provides a relatively mathematics-free or maybe more accurately Dirac bracket notation-free introduction to 1-D and 2-D (COSY and NOESY) experiments that would be appreciated by advanced undergraduates or beginning graduate students involved in undergraduate research experiences using NMR.

  5. NMR and NQR parameters of ethanol crystal

    CERN Document Server

    Milinkovic, M

    2012-01-01

    Electric field gradients and chemical shielding tensors of the stable monoclinic crystal phase of ethanol are computed. The projector-augmented wave (PAW) and gauge-including projector-augmented wave (GIPAW) models in the periodic plane-wave density functional theory are used. The crystal data from X-ray measurements, as well as the structures where either all atomic, or only hydrogen atom positions are optimized in the density functional theory are analyzed. These structural models are also studied by including the semi-empirical Van der Waals correction to the density functional theory. Infrared spectra of these five crystal models are calculated.

  6. NMR-based dynamics of free glycosaminoglycans in solution.

    Science.gov (United States)

    Pomin, Vitor H

    2014-08-01

    Glycosaminoglycans (GAGs) comprise a special class of complex carbohydrates endowed with numerous biological functions. Most of these functions are regulated by conformational arrangements or dynamical properties of GAGs in solution. Nuclear magnetic resonance (NMR) is a powerful technique used for dynamic analyses. Spin relaxation, scalar couplings, chemical shifts and nuclear Overhauser effect resonances are the commonest NMR parameters utilized in such analyses. Computational molecular dynamics are also very often employed in conjunction with, or restrained by, the NMR dataset. This report aims at describing the major NMR-based information available so far concerning the dynamical properties of free GAGs in solution. PMID:24887024

  7. Optimization and practical implementation of ultrafast 2D NMR experiments

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz Junior, Luiz H. K., E-mail: professorkeng@gmail.com [Universidade Federal de Sao Carlos (UFSC), SP (Brazil). Departamento de Quimica; Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Inst. de Quimica; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSC), SP (Brazil). Departamento de Quimica; Giraudeau, Patrick [Universite de Nantes (France). CNRS, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation

    2013-09-01

    Ultrafast 2D NMR is a powerful methodology that allows recording of a 2D NMR spectrum in a fraction of second. However, due to the numerous non-conventional parameters involved in this methodology its implementation is no trivial task. Here, an optimized experimental protocol is carefully described to ensure efficient implementation of ultrafast NMR. The ultrafast spectra resulting from this implementation are presented based on the example of two widely used 2D NMR experiments, COSY and HSQC, obtained in 0.2 s and 41 s, respectively. (author)

  8. Teaching NMR Using Online Textbooks

    OpenAIRE

    Hornak, Joseph P.

    1999-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has almost become an essential analytical tool for the chemist. High-resolution one- and multi-dimensional NMR, timedomain NMR, and NMR microscopy are but a few of the NMR techniques at a chemist's disposal to determine chemical structure and dynamics. Consequently, even small chemistry departments are finding it necessary to provide students with NMR training and experience in at least some of these techniques. The hands-on experience is readily ...

  9. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 55 figs

  10. NMR Spectroscopy - Theory

    Science.gov (United States)

    Lord, J.R.

    This web site begins with a simple quantum description of NMR and proceeds to introduce resonance absorption, relaxation, chemical shifts, and scalar couplings. This site will be useful for advanced undergraduate students needing a description of NMR that is more detailed than that given in most introductory Organic texts.

  11. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 32 refs., 56 figs

  12. Basics of NMR

    Science.gov (United States)

    Hornak, Joseph P.

    Dr. Joseph Hornak of the Rochester Institute of Technology presents this high quality hypertextbook for in-depth coverage of the physics and technique behind Nuclear Magnetic Resonance (NMR) (For Dr. Hornak's Basics of MRI, see the August 4, 1999 Scout Report for Science & Engineering). The material is presented in a detailed and clear manner without over simplifying the concepts. Chapters include "The Mathematics of NMR," "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Pulse Sequences," and much more. A chapter on "NMR Hardware" offers an overview of components (like the superconducting magnet and various coils) used in most NMR systems. The "Practical Considerations" chapter emphasizes spectroscopic techniques. With the screen split into two separate frames, explanatory graphics can be viewed alongside the text. A glossary and a list of symbols are also included in this carefully produced textbook.

  13. NMR logging apparatus

    Science.gov (United States)

    Walsh, David O; Turner, Peter

    2014-05-27

    Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.

  14. Solid state NMR

    International Nuclear Information System (INIS)

    This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry. Each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Dipolar Recoupling, by Niels Chr. Nielsen, Lasse A. Strassoe and Anders B. Nielsen. - Solid-State NMR Techniques for the Structural Determination of Amyloid Fibrils, by Jerry C. C. Chan. - Solid-State 19F-NMR of Peptides in Native Membranes, by Katja Koch, Sergii Afonin, Marco Ieronimo, Marina Berditsch and Anne S. Ulrich. - Probing Quadrupolar Nuclei by Solid-State NMR Spectroscopy: Recent Advances, by Christian Fernandez and Marek Pruski. - Solid State NMR of Porous Materials Zeolites and Related Materials, by Hubert Koller and Mark Weiss. - Solid-State NMR of Inorganic Semiconductors, by James P. Yesinowski.

  15. NMR studies of purine derivatives.

    Czech Academy of Sciences Publication Activity Database

    Procházková, Eliška; ?echová, Lucie; Jansa, Petr; Šála, Michal; Nencka, Radim; Dra?ínský, Martin

    Valtice : Masaryk University, 2012 - (Novotný, J.; Marek, R.). C13 ISBN 978-80-86441-43-6. [NMR Valtice. Central European NMR meeting. Biomolecular NMR /27./. 22.04.2012-25.04.2012, Valtice] Institutional research plan: CEZ:AV0Z40550506 Keywords : NMR * purines * tautomerism * long-range coupling Subject RIV: CC - Organic Chemistry

  16. NMR crystallography in pharmaceutical research.

    Czech Academy of Sciences Publication Activity Database

    Brus, Ji?í; Czernek, Ji?í; Urbanová, Martina; Kobera, Libor; Policianová, Olivia

    Valtice : -, 2011 - (Marek, R.; Novotný, J.). C-3 ISBN 978-80-86441-34-4. [NMR Valtice (Solid-state NMR). Central European NMR Meeting /26./. 01.05.2011-04.05.2011, Valtice] R&D Projects: GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : NMR * pharmaceutical Subject RIV: CB - Analytical Chemistry, Separation

  17. ?-NMR sample optimization

    CERN Document Server

    Zakoucka, Eva

    2013-01-01

    During my summer student programme I was working on sample optimization for a new ?-NMR project at the ISOLDE facility. The ?-NMR technique is well-established in solid-state physics and just recently it is being introduced for applications in biochemistry and life sciences. The ?-NMR collaboration will be applying for beam time to the INTC committee in September for three nuclei: Cu, Zn and Mg. Sample optimization for Mg was already performed last year during the summer student programme. Therefore sample optimization for Cu and Zn had to be completed as well for the project proposal. My part in the project was to perform thorough literature research on techniques studying Cu and Zn complexes in native conditions, search for relevant binding candidates for Cu and Zn applicable for ß-NMR and eventually evaluate selected binding candidates using UV-VIS spectrometry.

  18. Teaching NMR Using Online Textbooks

    Directory of Open Access Journals (Sweden)

    Joseph P. Hornak

    1999-12-01

    Full Text Available Nuclear magnetic resonance (NMR spectroscopy has almost become an essential analytical tool for the chemist. High-resolution one- and multi-dimensional NMR, timedomain NMR, and NMR microscopy are but a few of the NMR techniques at a chemist's disposal to determine chemical structure and dynamics. Consequently, even small chemistry departments are finding it necessary to provide students with NMR training and experience in at least some of these techniques. The hands-on experience is readily provided with access to state-of-the-art commercial spectrometers. Instruction in the principles of NMR is more difficult to achieve as most instructors try to teach NMR using single organic or analytical chemistry book chapters with static figures. This paper describes an online textbook on NMR spectroscopy called The Basics of NMR (http://www.cis.rit.edu/htbooks/nmr/ suitable for use in teaching the principles of NMR spectroscopy. The book utilizes hypertext and animations to present the principles of NMR spectroscopy. The book can be used as a textbook associated with a lecture or as a stand-alone teaching tool. Conference participants are encouraged to review the textbook and evaluate its suitability for us in teaching NMR spectroscopy to undergraduate chemistry majors.

  19. NMR analysis of proteins structure; Structure des proteines par RMN

    Energy Technology Data Exchange (ETDEWEB)

    Malliavin, Th. [Institut de Biologie Physico-Chimique, Lab. de Biochimie Theorique, 75 - Paris (France); Dardel, F. [Paris-5 Univ., Faculte de Pharmacie, Lab. de Cristallographie et RMN Biologiques, 75 (France)

    2002-01-01

    The nuclear magnetic resonance (NMR) analysis of proteins aims at determining the 3-D folding of the polypeptide chain. Because of the high number of nuclei observed in the samples, the NMR protein spectra are extremely complex. The different steps of the structure determination are: the preparation of the samples, the acquisition and processing of the NMR signal, the analysis and attribution of spectra, and the calculation of the coordinates of the atoms using the NMR spectra parameters. Content: 1 - proteins and peptides (composition and structure, secondary, tertiary and quaternary structure); 2 - NMR of proteins in solution (characteristics, structures determination, homonuclear experiments, heteronuclear experiments, proteins with a size higher than 20 kDa, intermolecular interactions, stability factors, internal molecular dynamics); 3 - structures calculation (calculation framework, distance geometry, molecular dynamics and simulated annealing, quality of the structure obtained). (J.S.)

  20. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1994-01-01

    This collection of reports demonstrate the extensive purview of NMR and its applications. The pellucid presentations provided include accounts on application of NMR spectroscopy to sciences and technologies of glassand ceramics; high-resolution solid-state NMR studies on ceramics; NMR studies of zeolite; NMR studies of higher-order structures of solid polymers; and organic thin films. Taken together with reviews in other volumes of this series, the present accountsably demonstrate that NMR is facile princeps when it comes to problem solving in most areas of science, including the medical sciences.

  1. Fluid-Rock Characterization and Interactions in NMR Well Logging

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Kishore K. Mohanty

    2005-09-05

    The objective of this report is to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. The advances made in the understanding of NMR fluid properties are summarized in a chapter written for an AAPG book on NMR well logging. This includes live oils, viscous oils, natural gas mixtures, and the relation between relaxation time and diffusivity. Oil based drilling fluids can have an adverse effect on NMR well logging if it alters the wettability of the formation. The effect of various surfactants on wettability and surface relaxivity are evaluated for silica sand. The relation between the relaxation time and diffusivity distinguishes the response of brine, oil, and gas in a NMR well log. A new NMR pulse sequence in the presence of a field gradient and a new inversion technique enables the T{sub 2} and diffusivity distributions to be displayed as a two-dimensional map. The objectives of pore morphology and rock characterization are to identify vug connectivity by using X-ray CT scan, and to improve NMR permeability correlation. Improved estimation of permeability from NMR response is possible by using estimated tortuosity as a parameter to interpolate between two existing permeability models.

  2. International symposium on NMR spectroscopy

    International Nuclear Information System (INIS)

    The publication consists of 32 papers and presentations from the field of NMR spectroscopy applications submitted to the International Symposium on NMR Spectroscopy held at Smolenice between 29 Sep and 3 Oct, 1980. (B.S.)

  3. NMR imaging technique

    International Nuclear Information System (INIS)

    This invention provides a method that can be adapted to existing NMR tomographic scanners of producing spectra of any given point in the image of the specimen slice, the intensity distribution of a selected resonance within an area of the image of the specimen slice, or an entire NMR spectrum of the given area. The method comprises acquiring n projections of the specimen slice, where n is greater than 1. Each of the projections is then shifted by ? f for the point (the frequency offset of the signal arising from the point, from the true chemical shift)

  4. Prediction of peak overlap in NMR spectra.

    Science.gov (United States)

    Hefke, Frederik; Schmucki, Roland; Güntert, Peter

    2013-06-01

    Peak overlap is one of the major factors complicating the analysis of biomolecular NMR spectra. We present a general method for predicting the extent of peak overlap in multidimensional NMR spectra and its validation using both, experimental data sets and Monte Carlo simulation. The method is based on knowledge of the magnetization transfer pathways of the NMR experiments and chemical shift statistics from the Biological Magnetic Resonance Data Bank. Assuming a normal distribution with characteristic mean value and standard deviation for the chemical shift of each observable atom, an analytic expression was derived for the expected overlap probability of the cross peaks. The analytical approach was verified to agree with the average peak overlap in a large number of individual peak lists simulated using the same chemical shift statistics. The method was applied to eight proteins, including an intrinsically disordered one, for which the prediction results could be compared with the actual overlap based on the experimentally measured chemical shifts. The extent of overlap predicted using only statistical chemical shift information was in good agreement with the overlap that was observed when the measured shifts were used in the virtual spectrum, except for the intrinsically disordered protein. Since the spectral complexity of a protein NMR spectrum is a crucial factor for protein structure determination, analytical overlap prediction can be used to identify potentially difficult proteins before conducting NMR experiments. Overlap predictions can be tailored to particular classes of proteins by preparing statistics from corresponding protein databases. The method is also suitable for optimizing recording parameters and labeling schemes for NMR experiments and improving the reliability of automated spectra analysis and protein structure determination. PMID:23585271

  5. Prediction of peak overlap in NMR spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hefke, Frederik [Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance (Germany); Schmucki, Roland [F. Hoffmann-La Roche AG (Switzerland); Guentert, Peter, E-mail: guentert@em.uni-frankfurt.de [Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance (Germany)

    2013-06-15

    Peak overlap is one of the major factors complicating the analysis of biomolecular NMR spectra. We present a general method for predicting the extent of peak overlap in multidimensional NMR spectra and its validation using both, experimental data sets and Monte Carlo simulation. The method is based on knowledge of the magnetization transfer pathways of the NMR experiments and chemical shift statistics from the Biological Magnetic Resonance Data Bank. Assuming a normal distribution with characteristic mean value and standard deviation for the chemical shift of each observable atom, an analytic expression was derived for the expected overlap probability of the cross peaks. The analytical approach was verified to agree with the average peak overlap in a large number of individual peak lists simulated using the same chemical shift statistics. The method was applied to eight proteins, including an intrinsically disordered one, for which the prediction results could be compared with the actual overlap based on the experimentally measured chemical shifts. The extent of overlap predicted using only statistical chemical shift information was in good agreement with the overlap that was observed when the measured shifts were used in the virtual spectrum, except for the intrinsically disordered protein. Since the spectral complexity of a protein NMR spectrum is a crucial factor for protein structure determination, analytical overlap prediction can be used to identify potentially difficult proteins before conducting NMR experiments. Overlap predictions can be tailored to particular classes of proteins by preparing statistics from corresponding protein databases. The method is also suitable for optimizing recording parameters and labeling schemes for NMR experiments and improving the reliability of automated spectra analysis and protein structure determination.

  6. Prediction of peak overlap in NMR spectra

    International Nuclear Information System (INIS)

    Peak overlap is one of the major factors complicating the analysis of biomolecular NMR spectra. We present a general method for predicting the extent of peak overlap in multidimensional NMR spectra and its validation using both, experimental data sets and Monte Carlo simulation. The method is based on knowledge of the magnetization transfer pathways of the NMR experiments and chemical shift statistics from the Biological Magnetic Resonance Data Bank. Assuming a normal distribution with characteristic mean value and standard deviation for the chemical shift of each observable atom, an analytic expression was derived for the expected overlap probability of the cross peaks. The analytical approach was verified to agree with the average peak overlap in a large number of individual peak lists simulated using the same chemical shift statistics. The method was applied to eight proteins, including an intrinsically disordered one, for which the prediction results could be compared with the actual overlap based on the experimentally measured chemical shifts. The extent of overlap predicted using only statistical chemical shift information was in good agreement with the overlap that was observed when the measured shifts were used in the virtual spectrum, except for the intrinsically disordered protein. Since the spectral complexity of a protein NMR spectrum is a crucial factor for protein structure determination, analytical overlap prediction can be used to identify potentially ction can be used to identify potentially difficult proteins before conducting NMR experiments. Overlap predictions can be tailored to particular classes of proteins by preparing statistics from corresponding protein databases. The method is also suitable for optimizing recording parameters and labeling schemes for NMR experiments and improving the reliability of automated spectra analysis and protein structure determination.

  7. NMR contribution to the actinides chemistry in aqueous solution

    International Nuclear Information System (INIS)

    Multi-nuclei NMR utilization, for actinides aqueous solutions studies, give data on the formed complexes. With the NMR parameters, such as chemical displacements, it is possible to accede to the complex structure, to the determination of the equilibrium constants and so to follow the whole chemical equilibriums occurring in aqueous solutions, with the mi-height width of the NMR signals: to the ligand-metal exchange speed, and with the Sz component of the total magnetization of the electronic spin: to some data on the actinides paramagnetic effects. (A.B.). 6 refs., 3 figs

  8. "Pure by NMR"?

    OpenAIRE

    Claridge, Td; Davies, Sg; Polywka, Me; Roberts, Pm; Russell, Aj; Savory, Ed; Smith, Ad

    2008-01-01

    Integration of a (13)C-(1)H satellite peak of a given (12)C-(1)H parent resonance within a quantitative (1)H NMR spectrum and comparison to the minor component represents a simple protocol for the accurate determination of diastereoisomeric ratios of up to 1000:1 (i.e., 99.8% de).

  9. NMR Studies of Purines.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Pohl, Radek

    Vol. 82. Oxford : Academic Press, 2014 - (Webb, G.), s. 59-113 ISBN 978-0-12-800184-4 R&D Projects: GA ?R GA13-24880S Institutional support: RVO:61388963 Keywords : NMR spectroscopy * purines * DFT calculations * chemical shifts Subject RIV: CC - Organic Chemistry

  10. Soils, Pores, and NMR

    Science.gov (United States)

    Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Haber, Agnes; Sucre, Oscar; Stingaciu, Laura; Stapf, Siegfried; Blümich, Bernhard

    2010-05-01

    Within Cluster A, Partial Project A1, the pore space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the pore geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 samples (Haber-Pohlmeier et al. 2010). Third, relaxometric information forms the basis of understanding magnetic resonance imaging (MRI) results. The general difficulty of imaging in soils are the inherent fast T2 relaxation times due to i) the small pore sizes, ii) presence of paramagnetic ions in the solid matrix, and iii) diffusion in internal gradients. The last point is important, since echo times can not set shorter than about 1ms for imaging purposes. The way out is either the usage of low fields for imaging in soils or special ultra-short pulse sequences, which do not create echoes. In this presentation we will give examples on conventional imaging of macropore fluxes in soil cores (Haber-Pohlmeier et al. 2010), and the combination with relaxometric imaging, as well as the advantages and drawbacks of low-field and ultra-fast pulse imaging. Also first results on the imaging of soil columns measured by SIP in Project A3 are given. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Waterflow Monitored by Tracer Transport in Natural Porous Media Using MRI." Vadose Zone J.: submitted. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Relaxation in a Natural soil: Comparison of Relaxometric Imaging, T1 - T2 Correlation and Fast-Field Cycling NMR." The Open Magnetic Resonance Journal: in print. Pohlmeier, A., S. Haber-Pohlmeier, et al. (2009). "A Fast Field Cycling NMR Relaxometry Study of Natural Soils." Vadose Zone J. 8: 735-742. Stingaciu, L. R., A. Pohlmeier, et al. (2009). "Characterization of unsaturated porous media by high-field and low-field NMR relaxometry." Water Resources Research 45: W08412

  11. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1989-01-01

    Commencing with Volume 21, the aim of this series is to produce a larger number of, relatively short but, timely and authoritative reviews. These will concentrate, in particular, on areas of NMR where recent progress, and developments, are of special interest and will reflect the many NMR developments occurring in the primary scientific literature. The present volume demonstrates the advances which can be made by the application of NMR techniques in many diverse areas of chemistry. Of particular significance is the account of Graphics-Aided NMR which will become an inprotant development in the use of NMR spectroscopy.

  12. Solid state NMR study of cumbaru flour

    International Nuclear Information System (INIS)

    The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T1H?). Knowing that the chemical structure and molecular dynamic are extremely necessary route to obtain information on the polysaccharides, this work contributes to the classification of the seed containing in the cumbaru fruit to get response on its application. To obtain the initial responses for our purposes some solid state NMR techniques were chosen. The CPMAS 13C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13C NMR spectrum showed the presence of domains with distinct molecular mobility, because these domains will differ basically in the distribution size and chain packing. The variable contact time experiment was used to analyse the distribution form of 13C decays, which give us more information about sample heterogeneity. The T1H?Hr values were obtained from the variable contact time and by delayed contact time experiment, because these parameter indicate the order of polysaccharides. From the values of this parameter, we found that this polysaccharide is completely non-ordered. (author)

  13. Some exercises in quantitative NMR imaging

    International Nuclear Information System (INIS)

    The articles represented in this thesis result from a series of investigations that evaluate the potential of NMR imaging as a quantitative research tool. In the first article the possible use of proton spin-lattice relaxation time T1 in tissue characterization, tumor recognition and monitoring tissue response to radiotherapy is explored. The next article addresses the question whether water proton spin-lattice relaxation curves of biological tissues are adequately described by a single time constant T1, and analyzes the implications of multi-exponentiality for quantitative NMR imaging. In the third article the use of NMR imaging as a quantitative research tool is discussed on the basis of phantom experiments. The fourth article describes a method which enables unambiguous retrieval of sign information in a set of magnetic resonance images of the inversion recovery type. The next article shows how this method can be adapted to allow accurate calculation of T1 pictures on a pixel-by-pixel basis. The sixth article, finally, describes a simulation procedure which enables a straightforward determination of NMR imaging pulse sequence parameters for optimal tissue contrast. (orig.)

  14. Applications of Unilateral NMR in Nondestructive Testing

    OpenAIRE

    Sharma, Shatrughan

    2004-01-01

    Für die Messung mit NMR-Spektroskopie wird eine Probe in der Regel vorbereitet, gemessen und anschließend entsorgt. In dem Fall, dass Probe nicht zerstört werden darf, gewinnt die Relaxationsanalyse bei niedrigen Feldern, i.e. die niedrig-auflösende NMR, an Bedeutung. Für große Proben ist die unilaterale NMR mit inhomogenen Feldern die Methode der Wahl. Unilaterale NMR oder inside-out NMR ist eine etablierte Technik der niedrig-auflösende NMR. Die NMR-MOUSE(Mobile Universal Surface Explorer) ...

  15. NMR used for Saudi crude asphaltenes

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy with proton (/sup 1/H) and carbon 13 (/sup 13/C) has been used to determine the structural characteristics of asphaltenes from four commercial Saudi Arabian crude oils. These characteristics are important to refiners that have deep conversion processes to determine yields from the residual fractions of the Saudi crudes, and to determine the operating parameters of the process units. The spectra obtained give some structural similarities among the crude oils, as well as some differences. Values of various structural parameters have been tabulated from the spectra

  16. NMR, water and plants

    International Nuclear Information System (INIS)

    This thesis describes the application of a non-destructive pulsed proton NMR method mainly to measure water transport in the xylem vessels of plant stems and in some model systems. The results are equally well applicable to liquid flow in other biological objects than plants, e.g. flow of blood and other body fluids in human and animals. The method is based on a pulse sequence of equidistant ? pulses in combination with a linear magnetic field gradient. (Auth.)

  17. NMR methods for beer characterization and quality control.

    Science.gov (United States)

    Rodrigues, J E; Gil, A M

    2011-12-01

    The use of high-resolution NMR spectroscopy in the brewing industry is described; most studies having aimed at assessing the composition of beer and its raw materials and correlating it to a variety of quality parameters. First, the application of NMR to the qualitative characterization of beer is reviewed, addressing both targeted and untargeted methods and focusing on both beer extracts and direct beer analysis. A subsequent chapter addresses the NMR studies, which envisage the development of new rapid methods for beer analysis and quality control, such as site-specific natural fractionation-NMR and multivariate data analysis methods for marker search or rapid compound quantification. Finally, possible future perspectives toward a deeper and more complete understanding of beer and its brewing process are discussed. PMID:22290708

  18. Rhodopsin-lipid interactions studied by NMR.

    Science.gov (United States)

    Soubias, Olivier; Gawrisch, Klaus

    2013-01-01

    The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200-nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60?m yields on the order of 500cm(2) of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated, and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By (2)H NMR order parameter measurements, it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by (1)H saturation-transfer NMR under conditions of magic angle spinning, we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. PMID:23374188

  19. DNA oligonucleotide conformations: high resolution NMR studies

    International Nuclear Information System (INIS)

    The present work describes a DNA double-helix model, which is well comparable with the models derived from fibre-diffraction studies. The model has a mononucleotide repeat with torsion angles in accordance with average geometries as derived from 1H NMR studies. Special attention was paid to reduce the number of short H-H nonbonding contacts, which are abundantly present in the 'classical' fibre-diffraction models. Chapter 3 describes the first complete assignment of a 1H NMR spectrum of a DNA tetramer, d(TAAT). Preliminary conformational data derived from the spectral parameters recorded at 27 0C are given. A more detailed analysis employing temperature-dependence studies is given in Chapter 4. (Auth.)

  20. Some nitrogen-14 NMR studies in solids

    International Nuclear Information System (INIS)

    The first order quadrupolar perturbation of the 14N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long 14N longitudinal relaxation times (T1) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between 14N and 1H. Using quadrupolar echo and CP techniques, the 14N quadrupolar coupling constants (e2qQ/h) and asymmetry parameters (eta) have been obtained for a variety of tetraalkylammonium compounds by observation of their quadrupolar powder patterns at various temperatures. For choline chloride and iodide the 14N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects

  1. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1994-01-01

    Over recent years, no other technique has grown to such importance as that of NMR spectroscopy. It is used in all branches of science where precise structural determination is required and where the nature of interactions and reactions in solution is being studied. Annual Reports on NMR Spectroscopy has established itself as a means for the specialist and non-specialist alike to become familiar with new applications of the technique in all branches of chemistry, including biochemistry, and pharmaceutics. This volume focuses on theoretical aspects of NMR nuclear shielding and on applications of NMR to polymer science.

  2. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1995-01-01

    Over recent years, no other technique has grown to such importance as that of NMR spectroscopy. It is used in all branches of science where precise structural determination is required and where the nature of interactions and reactions in solution is being studied. Annual Reports on NMR Spectroscopy has established itself as a means for the specialist and non-specialist alike to become familiar with new applications of the technique in all branches of chemistry, including biochemistry, and pharmaceutics. This volume focuses on theoretical aspects of NMR nuclear shielding and on applications of NMR to polymer science.

  3. Quantum spin Hamiltonians for the SU(2)_k WZW model

    CERN Document Server

    Nielsen, Anne E B; Sierra, German

    2011-01-01

    We propose to use null vectors in conformal field theories to derive model Hamiltonians of quantum spin chains and corresponding ground state wave function(s). The approach is quite general, and we illustrate it by constructing a family of Hamiltonians whose ground states are the chiral correlators of the SU(2)_k WZW model for integer values of the level k. The simplest example corresponds to k=1 and is essentially a nonuniform generalization of the Haldane-Shastry model with long-range exchange couplings. At level k=2, we analyze the model for N spin 1 fields. We find that the Renyi entropy and the two-point spin correlator show, respectively, logarithmic growth and algebraic decay. Furthermore, we use the null vectors to derive a set of algebraic, linear equations relating spin correlators within each model. At level k=1, these equations allow us to compute the two-point spin correlators analytically for the finite chain uniform Haldane-Shastry model and to obtain numerical results for the nonuniform case a...

  4. Ground states of unfrustrated spin Hamiltonians satisfy an area law

    International Nuclear Information System (INIS)

    We show that ground states of unfrustrated quantum spin-1/2 systems on general lattices satisfy an entanglement area law, provided that the Hamiltonian can be decomposed into nearest-neighbor interaction terms that have entangled excited states. The ground state manifold can be efficiently described as the image of a low-dimensional subspace of low Schmidt measure, under an efficiently contractible tree-tensor network. This structure gives rise to the possibility of efficiently simulating the complete ground space (which is in general degenerate). We briefly discuss 'non-generic' cases, including highly degenerate interactions with product eigenbases, using a relationship to percolation theory. We finally assess the possibility of using such tree tensor networks to simulate almost frustration-free spin models.

  5. Ground states of unfrustrated spin Hamiltonians satisfy an area law

    CERN Document Server

    de Beaudrap, Niel; Eisert, Jens

    2010-01-01

    We show that ground states of unfrustrated quantum spin-1/2 systems on general lattices satisfy an entanglement area law, provided that the Hamiltonian can be decomposed into nearest-neighbor interaction terms which have entangled excited states. The ground state manifold can be efficiently described as the image of a low-dimensional subspace of low Schmidt measure, under an efficiently contractible tree-tensor network. This structure gives rise to the possibility of efficiently simulating the complete ground space (which is in general degenerate). We briefly discuss "non-generic" cases, including highly degenerate interactions with product eigenbases, using a relationship to percolation theory. We finally assess the possibility of using such tree tensor networks to simulate almost frustration-free spin models.

  6. The determination of sulfoxide configuration in six-membered rings using NMR specroscopy and DFT calculations.

    Czech Academy of Sciences Publication Activity Database

    Dra?ínský, Martin; Pohl, Radek; Slav?tínská, Lenka; Jank?, J.; Bud?šínský, Miloš

    2011-01-01

    Ro?. 22, ?. 3 (2011), s. 356-366. ISSN 0957-4166 R&D Projects: GA ?R GA203/09/1919 Institutional research plan: CEZ:AV0Z40550506 Keywords : NMR * calculation of NMR parameters * sulfoxides * configuration Subject RIV: CC - Organic Chemistry Impact factor: 2.652, year: 2011

  7. Introduction to the conformational investigation of peptides and proteins by using two-dimensional proton NMR experiments

    International Nuclear Information System (INIS)

    This report presents the elementary bases for an initiation to the conformational study of peptides and proteins by using two-dimensional proton NMR experiments. First, some general features of protein structures are summarized. A second chapter is devoted to the basic NMR experiments and to the spectral parameters which provide a structural information. This description is illustrated by NMR spectra of peptides. The third chapter concerns the most standard two-dimensional proton NMR experiments and their use for a conformational study of peptides and proteins. Lastly, an example of NMR structural investigation of a peptide is reported

  8. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1985-01-01

    The current extent of applications of NMR spectroscopy to molecular problems is indicated by the diversity of the reviews presented in this volume. Dr. H.W.E. Rattle reports on NMR of amino acids, peptides, and proteins, which brings his account in Volume 11A up to date.

  9. Nuclear magnetic resonance (NMR) tomography

    International Nuclear Information System (INIS)

    A brief survey of the working principle of the NMR technique in diagnostical medicine is given. Its clinical usefulness for locating tumors, diagnosing various other diseases, such as some mental illnesses and multiple sclerosis, and its possibilities for studying biochemical processes in vivo are mentioned. The price of NMR image scanners and the problems of the strong magnetic field around the machines are mentioned

  10. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A

    1986-01-01

    NMR spectroscopy has grown to be a vitally important technique with applications in many areas of science. Annual Reports on NMR Spectroscopy is quickly becoming the source for the latest information on current progress, both experimental and theoretical. Chemists in a variety of disciplines will be interested in this up-to-date, comprehensive series.

  11. Annual reports on NMR spectroscopy

    CERN Document Server

    1991-01-01

    This book is part of a series on spectroscopy, and covers NMR studiesof isolated spin-pairs in the solid state, the oxidation state dependence of transition metal shieldings, the Cinderella nuclei, nuclear spin relaxation in organic systems, solutions of macromolecules and aggregates and the NMR of coals and coal products. Related titlesare volumes 20, 21 and 22 in the series.

  12. Structural Biology: Practical NMR Applications

    CERN Document Server

    Teng, Quincy

    2005-01-01

    This textbook begins with an overview of NMR development and applications in biological systems. It describes recent developments in instrument hardware and methodology. Chapters highlight the scope and limitation of NMR methods. While detailed math and quantum mechanics dealing with NMR theory have been addressed in several well-known NMR volumes, chapter two of this volume illustrates the fundamental principles and concepts of NMR spectroscopy in a more descriptive manner. Topics such as instrument setup, data acquisition, and data processing using a variety of offline software are discussed. Chapters further discuss several routine stategies for preparing samples, especially for macromolecules and complexes. The target market for such a volume includes researchers in the field of biochemistry, chemistry, structural biology and biophysics.

  13. Fundamentals of Protein NMR Spectroscopy

    CERN Document Server

    Rule, Gordon S

    2006-01-01

    NMR spectroscopy has proven to be a powerful technique to study the structure and dynamics of biological macromolecules. Fundamentals of Protein NMR Spectroscopy is a comprehensive textbook that guides the reader from a basic understanding of the phenomenological properties of magnetic resonance to the application and interpretation of modern multi-dimensional NMR experiments on 15N/13C-labeled proteins. Beginning with elementary quantum mechanics, a set of practical rules is presented and used to describe many commonly employed multi-dimensional, multi-nuclear NMR pulse sequences. A modular analysis of NMR pulse sequence building blocks also provides a basis for understanding and developing novel pulse programs. This text not only covers topics from chemical shift assignment to protein structure refinement, as well as the analysis of protein dynamics and chemical kinetics, but also provides a practical guide to many aspects of modern spectrometer hardware, sample preparation, experimental set-up, and data pr...

  14. Flow units from integrated WFT and NMR data

    Energy Technology Data Exchange (ETDEWEB)

    Kasap, E.; Altunbay, M.; Georgi, D.

    1997-08-01

    Reliable and continuous permeability profiles are vital as both hard and soft data required for delineating reservoir architecture. They can improve the vertical resolution of seismic data, well-to-well stratigraphic correlations, and kriging between the well locations. In conditional simulations, permeability profiles are imposed as the conditioning data. Variograms, covariance functions and other geostatistical indicators are more reliable when based on good quality permeability data. Nuclear Magnetic Resonance (NMR) logging and Wireline Formation Tests (WFT) separately generate a wealth of information, and their synthesis extends the value of this information further by providing continuous and accurate permeability profiles without increasing the cost. NMR and WFT data present a unique combination because WFTs provide discrete, in situ permeability based on fluid-flow, whilst NMR responds to the fluids in the pore space and yields effective porosity, pore-size distribution, bound and moveable fluid saturations, and permeability. The NMR permeability is derived from the T{sub 2}-distribution data. Several equations have been proposed to transform T{sub 2} data to permeability. Regardless of the transform model used, the NMR-derived permeabilities depend on interpretation parameters that may be rock specific. The objective of this study is to integrate WFT permeabilities with NMR-derived, T{sub 2} distribution-based permeabilities and thereby arrive at core quality, continuously measured permeability profiles. We outlined the procedures to integrate NMR and WFT data and applied the procedure to a field case. Finally, this study advocates the use of hydraulic unit concepts to extend the WFT-NMR derived, core quality permeabilities to uncored intervals or uncored wells.

  15. Solid state NMR of sulfa-drugs

    Energy Technology Data Exchange (ETDEWEB)

    Portieri, A

    2001-07-01

    This work has been a study of systems, mostly of sulfa-drugs, showing polymorphic behaviour. Using different means as solid state NMR, X-ray analysis, * and theoretical calculations, we have seen how it is possible to understand results obtained from the different techniques, proving how the study of polymorphic systems needs cooperative advice from the different techniques that are able to detect polymorphic differences. Within the sulfa-drugs I have been mostly concentrating on sulfanilamide, studying {sup 13}C and {sup 15}N solid state NMR spectra of the different polymorphs. The NMR parameters that have been most interesting to study, have been the relaxation times that have revealed complicated motion of the molecule despite it being a small molecule. In order to obtain detailed information from {sup 15}N spectra it has been necessary to enrich the samples and this has enabled a study of the shielding tensors of the nitrogens in the molecule. {sup 13}C spectra were also recorded of systems studied sulfathiazole solvates, that proved to show some of the same solid state effects in the NMR spectra as sulfanilamide. Shielding calculations have proved to be still limited in order to obtain reliable information on the shielding of both {sup 13}C and {sup 15}N nuclei but considering hydrogen-bonded molecules, as opposed to isolated molecules, seemed to have improved the calculations quite a lot, so that some idea of intermolecular effects could be deducted. Exact positions of the hydrogen has proved to be essential as well in order to improve the calculations. Finally a case study for the REDOR pulse sequence has been carried out. Different attempts to understand the effects influencing this particular experiment have been carried out on 20% and 99% doubly enriched glycine, as well as on a particular sample, doubly enriched BRL55834, but the internuclear distances measured with this technique still displayed some uncertainties that made results not thoroughly reliable. (author)

  16. Solid state NMR of sulfa-drugs

    International Nuclear Information System (INIS)

    This work has been a study of systems, mostly of sulfa-drugs, showing polymorphic behaviour. Using different means as solid state NMR, X-ray analysis, * and theoretical calculations, we have seen how it is possible to understand results obtained from the different techniques, proving how the study of polymorphic systems needs cooperative advice from the different techniques that are able to detect polymorphic differences. Within the sulfa-drugs I have been mostly concentrating on sulfanilamide, studying 13C and 15N solid state NMR spectra of the different polymorphs. The NMR parameters that have been most interesting to study, have been the relaxation times that have revealed complicated motion of the molecule despite it being a small molecule. In order to obtain detailed information from 15N spectra it has been necessary to enrich the samples and this has enabled a study of the shielding tensors of the nitrogens in the molecule. 13C spectra were also recorded of systems studied sulfathiazole solvates, that proved to show some of the same solid state effects in the NMR spectra as sulfanilamide. Shielding calculations have proved to be still limited in order to obtain reliable information on the shielding of both 13C and 15N nuclei but considering hydrogen-bonded molecules, as opposed to isolated molecules, seemed to have improved the calculations quite a lot, so that some idea of intermolecular effects that some idea of intermolecular effects could be deducted. Exact positions of the hydrogen has proved to be essential as well in order to improve the calculations. Finally a case study for the REDOR pulse sequence has been carried out. Different attempts to understand the effects influencing this particular experiment have been carried out on 20% and 99% doubly enriched glycine, as well as on a particular sample, doubly enriched BRL55834, but the internuclear distances measured with this technique still displayed some uncertainties that made results not thoroughly reliable. (author)

  17. Two dimensional solid state NMR

    International Nuclear Information System (INIS)

    This thesis illustrates, by discussing some existing and newly developed 2D solid state experiments, that two-dimensional NMR of solids is a useful and important extension of NMR techniques. Chapter 1 gives an overview of spin interactions and averaging techniques important in solid state NMR. As 2D NMR is already an established technique in solutions, only the basics of two dimensional NMR are presented in chapter 2, with an emphasis on the aspects important for solid spectra. The following chapters discuss the theoretical background and applications of specific 2D solid state experiments. An application of 2D-J resolved NMR, analogous to J-resolved spectroscopy in solutions, to natural rubber is given in chapter 3. In chapter 4 the anisotropic chemical shift is mapped out against the heteronuclear dipolar interaction to obtain information about the orientation of the shielding tensor in poly-(oxymethylene). Chapter 5 concentrates on the study of super-slow molecular motions in polymers using a variant of the 2D exchange experiment developed by us. Finally chapter 6 discusses a new experiment, 2D nutation NMR, which makes it possible to study the quadrupole interaction of half-integer spins. 230 refs.; 48 figs.; 8 tabs

  18. 17O NMR studies of substituted 1,3,4-oxadiazoles.

    Science.gov (United States)

    Gierczyk, B?a?ej; Zalas, Maciej; Ka?mierczak, Marcin; Grajewski, Jakub; Pankiewicz, Rados?aw; Wyrzykiewicz, Bo?ena

    2011-10-01

    Three series of substituted 1,3,4-oxadiazoles were studied by (17)O NMR spectroscopy. Chemical shifts values were correlated with empirical Hammett parameters as well as calculated bond lengths and chemical shielding values. PMID:21919055

  19. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A; McCarthy, M J

    1995-01-01

    Over recent years, no other technique has grown to such importance as that of NMR spectroscopy. It is used in all branches of science where precise structural determination is required and where the nature of interactions and reactions in solution is being studied. Annual Reports on NMR Spectroscopy has established itself as a means for the specialist and non-specialist alike to become familiar with new applications of the technique in all branches of chemistry, including biochemistry, and pharmaceutics. This volume focuses on theoretical aspects of NMR nuclear shielding and on applications of

  20. Dynamic NMR of nano- and microstructured materials

    International Nuclear Information System (INIS)

    The fast technological advancement which took place over the past few decades sustained the development of various categories of advanced polymeric, composite and porous materials, with complex physical and chemical properties determined by their structure and dynamics at nano- and micrometer levels. This brought forth the necessity of combining different methods of analysis, which cover multiple length scales, in order to allow for a comprehensive characterization and a valid prediction of a material's macroscopic behaviour. The purpose of this work was to characterize the structure and dynamics of various types of nano- and micro structured systems, such as silane crosslinked poly(ethylene), cement-in-polymer dispersion with different compositions or model and natural porous media, using a combination of nuclear magnetic resonance (NMR) methods that provide relevant information on different length scales of interest. Data processing and interpretation was facilitated by self-made computational procedures and mathematical models. The different subjects approached in this work are briefly presented in Chapter 1 (Introduction) and discussed in detail further on in an order according to the length scale of the motion probed. In Chapter 2 proton NMR wideline spectroscopy is used to obtain information on the phase composition, molecular mobility and domain sizes of crosslinked poly(ethylene) (PE), a polymer commonly used in a broad range of applications, from day-to-day life basic commodities like water and sewage pipes, to insulating coatings for medium and high voltage wires. Due to its industrial importance, this type of PE has been previously characterized using a variety of methods. The novelty brought by this study is the quantitative analysis of the spin diffusion (SD) coefficients and domain sizes of different phases by a dedicated software developed for solving the spin diffusion equations for a lamellar morphology, using as input data extracted from NMR double quantum filtered SD experiments and including a series of bonds for and minimizing uncertainties in the estimation of essential parameters. Recently developed cement-in-polymer dispersions (c/p) with different compositions and cement to polymer ratios are investigated in Chapters 3 and 4, by a vast array of NMR techniques, that probe, on different length scales, the structure of the investigated specimens, as well as the dynamics of water transport inside the materials. Chapter 3 presents the results obtained using multinuclear solid state magic angle spinning NMR to probe, at nanometer level, the structure of cement-in-polymer dispersions. The hydration effects and crystallization of the inorganic matrix are probed by 29Si NMR while the chemical reactions of the organic phase are quantified by 13C cross-polarization; the results are correlated with data offered by other analysis techniques. The study of hydrated c/p is continued in Chapter 4, where proton NMR imaging is employed to obtain information about the microstructural changes which take place upon exposure to water at different temperatures. The water transport in the c/p matrix is monitored on line and the hydration phenomenon, together with information about the physical suffered by the samples are discussed with regard to polymer type, amount and curing conditions. A simple mathematical model of diffusion in a cylindrical system, involving time dependent diffusion coefficients and variable surface concentrations, is used to predict the manner in which the water amount inside the organic/cementitious pastes evolves in time. Further on, the effects of diffusive and advective transport in model and natural porous media are systematically investigated in Chapters 5 and 6. NMR exchange relaxometry is known as a very powerful tool for probing the structure and dynamics of fully or partially hydrated porous systems, but, until know, no information existed on how the effects of slow advective transport - a phenomenon of considerable interest for different branches of science and industry - are reflected i

  1. Essential NMR for Scientists and Engineers

    Science.gov (United States)

    Blömich, Bernhard

    ESSENTIAL NMR is a set of lecture notes for scientists and engineers who want to brush up on their knowledge of NMR. This book is also a compendium for graduate and postgraduate students of physics and chemistry as well as for their teachers, covering all fields of NMR, i.e. NMR methodology and hardware, chemical analysis, 2D-spectroscopy, NMR imaging, flow NMR, and quality control NMR. The material, selected and organized for a one-semester course, is presented with pairs of pages addressing particular topics.

  2. Rotary motion of complexes in solution and NMR correlation times

    International Nuclear Information System (INIS)

    Considered is the model of retarded rotation of octahedral aquacomplexes of transition metal ions (Mn2+, Cu2+, V2+, Gd2+, NpO2+) in solution with regard to activation energy distribution according to complex freedom degrees. Proceeding from comparison with experimental values of NMR rotation correlation times a conclusion is made that water molecules in aquacomplex participate in the activation process of rotary motion. An expression is obtained which connects NMR - correlation time of complex rotary motion with their structural parameters in solution

  3. NMR of superfluid 3He in anisotropic aerogel

    CERN Document Server

    Kunimatsu, T; Izumina, K; Matsubara, A; Sasaki, Y; Kubota, M; Ishikawa, O; Mizusaki, T; Bunkov, Yu M; Bunkov, Yu.M.

    2006-01-01

    We report on orientation of the order parameter in the 3He-A and 3He-B phases caused by aerogel anisotropy. In 3He-A we have observed relatively homogeneous NMR line with an anomalously large negative frequency shift. We can attribute this effect to an orientation of orbital momentum along the axis of density anisotropy. The similar orientation effect we have seen in 3He-B. We can measure the A-phase Leggett frequency, which shows the same energy gap suppression as in the B-phase. We observe a correlation of A - B transition temperature and NMR frequency shift.

  4. Carbon-13 NMR studies of liquid crystals

    International Nuclear Information System (INIS)

    High resolution, proton decoupled 13C nmr are observed for a series of neat nematic liquid crystals, the p-alkoxyazoxybenzenes, and a smectic-A liquid crystal, diethylazoxydibenzoate in a magnetic field of 23 kG. The (uniaxial) order parameters S = less than P2(costheta) greater than are found to be about 0.4 and 0.9 for the nematic and smectic-A phase respectively at the clearing points. The order parameter increases with decreasing temperature in the nematic phase but is constant, or nearly so, with temperature in the smectic-A phase. In the nematic series studied, the ordering exhibits an even-odd alternation along the series and qualitative agreement with a recent theory due to Marcelja is found. In both phases, the spectra show that the molecule rotates rapidly about its long axis. Tentative conclusions about molecular conformational motion and 14N spin relaxation are presented for both nematic and smectic-A phases. In the smectic-A phase, the sample is rotated about an axis perpendicular to H0 and the resulting spectra are dicusssed. The theory of observed chemical shifts in liquid crystals is discussed and equations are derived which relate the nmr spectra of liquid-crystals to the order parameters. A model for the smectic-C phase due to Luz and Meiboom and Doane is described and lineshapes are determined on the basis of this model for special cases. The dependence of the order parameters on the molecular potential which give rise to the various degrees of order in the different liquid crystalline phases is examined. To a good approximation the functional dependence of the order parameters on the molecular potential is shown to be a simple one in the limit of small tilt angle in the smectic-C phase

  5. Practical applications of NMR in civil engineering

    OpenAIRE

    Wolter, B.; Kohl, F.; Surkowa, N.; Dobmann, G.

    2003-01-01

    By studying Hydrogen Nuclear Magnetic Resonance (1H-NMR) signals of water in porous materials, it is possible to determine their properties of water storage and transport. Besides, NMR studies can provide detailed information about the porous microstructure (porosity, pore-size distribution) of these materials. This approach is used in geophysical applications of NMR (e.g. for subsoil investigations), whereas a special NMR instrumentation ("NMR logging" tool) is lowered down into a drilled bo...

  6. Compact orthogonal NMR field sensor

    Science.gov (United States)

    Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL)

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  7. NMR characterization of thin films

    Science.gov (United States)

    Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2010-06-15

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  8. Optical pumping and xenon NMR

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen

  9. PROBING PLANT METABOLISM WITH NMR.

    OpenAIRE

    Ratcliffe, Rg; Shachar-hill, Y.

    2001-01-01

    Analytical methods for probing plant metabolism are taking on new significance in the era of functional genomics and metabolic engineering. Among the available methods, nuclear magnetic resonance (NMR) spectroscopy is a technique that can provide insights into the integration and regulation of plant metabolism through a combination of in vivo and in vitro measurements. Thus NMR can be used to identify, quantify, and localize metabolites, to define the intracellular environment, and to explore...

  10. Ligand screening by saturation-transfer difference (STD) NMR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, V V

    2005-04-26

    NMR based methods to screen for high-affinity ligands have become an indispensable tool for designing rationalized drugs, as these offer a combination of good experimental design of the screening process and data interpretation methods, which together provide unprecedented information on the complex nature of protein-ligand interactions. These methods rely on measuring direct changes in the spectral parameters, that are often simpler than the complex experimental procedures used to study structure and dynamics of proteins. The goal of this review article is to provide the basic details of NMR based ligand-screening methods, with particular focus on the saturation transfer difference (STD) experiment. In addition, we provide an overview of other NMR experimental methods and a practical guide on how to go about designing and implementing them.

  11. Variable-temperature NMR and conformational analysis of Oenothein B

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Suzana C.; Carvalho, Ariadne G.; Fortes, Gilmara A.C.; Ferri, Pedro H.; Oliveira, Anselmo E. de, E-mail: suzana.quimica.ufg@hotmail.com [Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Instituto de Quimica

    2014-02-15

    Oenothein B is a dimeric hydrolyzable tannin with a wide range of biological activities, such as antitumour, anti-inflammatory and antiviral. Its nuclear magnetic resonance (NMR) at room temperature show duplications and broadening of signals. Experiments of 1D and 2D NMR at lower temperatures were useful for the complete NMR assignments of all hydrogens and carbons. The 3D structure of the most stable conformer was determined for the first time by nuclear Overhauser effect spectroscopy (NOESY) experiment (-20 deg C) and density functional theory (DFT)(B3LYP/6-31G)/ polarizable continuum model (PCM) quantum chemical calculations. The favoured conformation showed a highly compacted geometry and a lack of symmetry, in which the two valoneoyl groups showed distinct conformational parameters and stabilities. (author)

  12. jsNMR: an embedded platform-independent NMR spectrum viewer.

    Science.gov (United States)

    Vosegaard, Thomas

    2015-04-01

    jsNMR is a lightweight NMR spectrum viewer written in JavaScript/HyperText Markup Language (HTML), which provides a cross-platform spectrum visualizer that runs on all computer architectures including mobile devices. Experimental (and simulated) datasets are easily opened in jsNMR by (i) drag and drop on a jsNMR browser window, (ii) by preparing a jsNMR file from the jsNMR web site, or (iii) by mailing the raw data to the jsNMR web portal. jsNMR embeds the original data in the HTML file, so a jsNMR file is a self-transforming dataset that may be exported to various formats, e.g. comma-separated values. The main applications of jsNMR are to provide easy access to NMR data without the need for dedicated software installed and to provide the possibility to visualize NMR spectra on web sites. PMID:25641013

  13. Medical applications of NMR imaging and NMR spectroscopy with stable isotopes. Summary

    International Nuclear Information System (INIS)

    The current status of NMR imaging and NMR spectroscopy are summarized. For the most part examples from the March 1983 Puerto Rico symposium are used to illustrate the utility of NMR in medicine. 18 refs., 5 figs

  14. NMR of a Phospholipid: Modules for Advanced Laboratory Courses

    Science.gov (United States)

    Gaede, Holly C.; Stark, Ruth E.

    2001-09-01

    A laboratory project is described that builds upon the NMR experience undergraduates receive in organic chemistry with a battery of NMR experiments that investigate egg phosphatidylcholine (egg PC). This material, often labeled in health food stores as lecithin, is a major constituent of mammalian cell membranes. The NMR experiments may be used to make resonance assignments, to study molecular organization in model membranes, to test the effects of instrumental parameters, and to investigate the physics of nuclear spin systems. A suite of modular NMR exercises is described, so that the instructor may tailor the laboratory sessions to biochemistry, instrumental analysis, or physical chemistry. The experiments include solution-state one-dimensional (1D) 1H, 13C, and 31P experiments; two-dimensional (2D) TOtal Correlated SpectroscopY (TOCSY); and the spectral editing technique of Distortionless Enhancement by Polarization Transfer (DEPT). To demonstrate the differences between solution and solid-state NMR spectroscopy and instrumentation, a second set of experiments generates 1H, 13C, and 31P spectra of egg PC dispersed in aqueous solution, under both static and magic-angle spinning conditions.

  15. Evaluation of abdominal aortic aneurysms with NMR imaging

    International Nuclear Information System (INIS)

    Seven patients (5 male and 2 female, age range from 50 to 88) with angiographic proven abdominal aortic aneurysms were evaluated with NMR imaging (1.5 K gauss system) of the abdomen. Images were obtained in transverse, coronal and saggital planes with three radiofrequency pulse sequences [saturation recovery (SR), inversion recovery (IR), and spin echo (SE)]. All of the aneurysms were identified as to site and relative size with NMR images. The lumen in which there was flowing blood was always dark (low intensity), whereas the aneurysmal area which contained presumed clot was brighter (high intensity) on SR images. Although the size, location and relationship to other blood vessels was best demonstrated on aortography, NMR images provided similar information in all cases. NMR images correctly demonstrated thrombus in six cases. The authors conclude that NMR imaging provides a clear delineation of the anatomy of abdominal aortic aneurysms. In addition it can provide information concerning tissue type, i.e., it distinguished clot from moving blood. It may be possible in the future to further characterize atherosclerotic and other pathological changes in vessel architecture by using various pulse sequences and timing parameters to provide in vivo histological typing

  16. Bootstrap calibration and uncertainty estimation of downhole NMR hydraulic conductivity estimates in an unconsolidated aquifer.

    Science.gov (United States)

    Parsekian, A D; Dlubac, K; Grunewald, E; Butler, J J; Knight, R; Walsh, D O

    2015-01-01

    Characterization of hydraulic conductivity (K) in aquifers is critical for evaluation, management, and remediation of groundwater resources. While estimates of K have been traditionally obtained using hydraulic tests over discrete intervals in wells, geophysical measurements are emerging as an alternative way to estimate this parameter. Nuclear magnetic resonance (NMR) logging, a technology once largely applied to characterization of deep consolidated rock petroleum reservoirs, is beginning to see use in near-surface unconsolidated aquifers. Using a well-known rock physics relationship-the Schlumberger Doll Research (SDR) equation--K and porosity can be estimated from NMR water content and relaxation time. Calibration of SDR parameters is necessary for this transformation because NMR relaxation properties are, in part, a function of magnetic mineralization and pore space geometry, which are locally variable quantities. Here, we present a statistically based method for calibrating SDR parameters that establishes a range for the estimated parameters and simultaneously estimates the uncertainty of the resulting K values. We used co-located logging NMR and direct K measurements in an unconsolidated fluvial aquifer in Lawrence, Kansas, USA to demonstrate that K can be estimated using logging NMR to a similar level of uncertainty as with traditional direct hydraulic measurements in unconsolidated sediments under field conditions. Results of this study provide a benchmark for future calibrations of NMR to obtain K in unconsolidated sediments and suggest a method for evaluating uncertainty in both K and SDR parameter values. PMID:24520904

  17. NMR relaxation times of trabecular bone-reproducibility, relationships to tissue structure and effects of sample freezing

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy provides a potential tool for non-invasive evaluation of the trabecular bone structure. The objective of this study was to determine the reproducibility of the NMR relaxation parameters (T2, Carr-Purcel-T2, T1?) for fat and water and relate those to the structural parameters obtained by micro-computed tomography (?CT). Especially, we aimed to evaluate the effect of freezing on the relaxation parameters. For storing bone samples, freezing is the standard procedure during which the biochemical and cellular organization of the bone marrow may be affected. Bovine trabecular bone samples were stored at -20 0C for 7 days and measured by NMR spectroscopy before and after freezing. The reproducibility of NMR relaxation parameters, as expressed by the coefficient of variation, ranged from 3.1% to 27.9%. In fresh samples, some correlations between NMR and structural parameters (Tb.N, Tb.Sp) were significant (e.g. the relaxation rate for T2 of fat versus Tb.Sp: r = -0.716, p < 0.01). Freezing did not significantly change the NMR relaxation times but the correlations between relaxation parameters and the ?CT structural parameters were not statistically significant after freezing, suggesting some nonsystematic alterations of the marrow structure. Therefore, the use of frozen bone samples for NMR relaxation studies may provide inferior information about the trabecular bone structmation about the trabecular bone structure.

  18. Pulsed zero field NMR of solids and liquid crystals

    International Nuclear Information System (INIS)

    This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs

  19. Pulsed zero field NMR of solids and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, A.M.

    1987-02-01

    This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs.

  20. NMR Analysis of 2-(2?, 3?-dihydro-1?H-inden-1?-yl-1H-indene

    Directory of Open Access Journals (Sweden)

    PETER SPITELLER

    2001-12-01

    Full Text Available 1H, 13C and two dimensional NMR analyses were applied to determine the NMR parameters of 2-(2?,3?-dihydro-1?H-inden-1?-yl-1H-indene. The chemical shifts of all the H- and C-atoms, as well as the appropriate coupling constants were determined and the complete NMR resonance assignments of the molecule are given. The predicted patterns of the four different H atoms of the two methylene groups of the indane structural element coincided completely with the complex patterns in the NMR spectra.

  1. Joint numerical microscale simulations of multi-phase flow and NMR relaxation behaviour in porous media

    Science.gov (United States)

    Mohnke, O.; Ahrenholz, B.

    2011-12-01

    Nuclear Magnetic Resonance (NMR) is a useful tool for analyzing gas (methane) and fluids (water, oil) in rock formations in order to derive transport and storage properties such as pore-size distributions or relative permeability. Even though there is considerable NMR data available about hydraulic properties of rock formations, this information is only empirical. Thus, the aim of this paper is to present joint NMR and multi-phase flow simulations in micro-scale pore systems derived from micro-CT images to quantify relationships between NMR parameters and transport and storage properties of partially saturated rocks. Hereby, the NMR differential equations were implemented using an advection/diffusion lattice-Boltzmann method (LBM) where the flow field is computed by a coupled LBM CFD solver. The results of numerical imbibition and drainage experiments quantitatively agree with laboratory experiments with regard to frequently found peak shifts and bimodal NMR decay time distributions related to residual water in films and corners as well as to fluids/gases trapped in large pores. This numerical framework enables one to quantitatively describe NMR surface and bulk relaxation processes, diffusive coupling along with the multi-phase flow properties of partially saturated porous systems. Furthermore, it is a viable alternative to the more time-consuming and less controllable laboratory experiments. Such virtual experimental setups can considerably help to benchmark and validate statistical network models to better understand hydraulic properties of partially saturated rocks by using experimentally obtained NMR data.

  2. Quantitative chemical analysis by NMR

    International Nuclear Information System (INIS)

    This paper reports that nuclear magnetic resonance (NMR) spectroscopy offers several important advantages as a technique for quantitative chemical analysis, including the ease with which multicomponent mixtures can be analyzed, the nondestructive nature of NMR, and the direct proportionality of the integrated resonance intensity (I) and concentration (C) of nuclei giving the resonance: I = kC. With proper attention to experimental conditions, the proportionality constant is the same for all resonances in a spectrum. Thus NMR differs substantially from chromatographic methods and from together spectroscopic methods, which require a predetermined response factor for each compound being determined. Relative concentrations can be obtained directly from relative resonance intensities while absolute concentrations can be obtained by adding a known concentration of another compound as an internal intensity standard

  3. Understanding NMR: self-learning manual

    International Nuclear Information System (INIS)

    This initiation to the principles of nuclear magnetic resonance (NMR) imaging allows to understand the essential basic physical principles for the realization and the interpretation of an NMR examination. (J.S.)

  4. Radiofrequency and magnet technology in medical NMR

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) is briefly described, particularly its rf and magnet aspects. Particular attention is given to the duplexer, the rf coils, and new kinds of magnets for remote sensing NMR

  5. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

  6. Radiofrequency and magnet technology in medical NMR

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, E.

    1984-01-01

    Nuclear magnetic resonance (NMR) is briefly described, particularly its rf and magnet aspects. Particular attention is given to the duplexer, the rf coils, and new kinds of magnets for remote sensing NMR. (LEW)

  7. Two-dimensional NMR spectrometry

    International Nuclear Information System (INIS)

    This article is the second in a two-part series. In part one (ANALYTICAL CHEMISTRY, May 15) the authors discussed one-dimensional nuclear magnetic resonance (NMR) spectra and some relatively advanced nuclear spin gymnastics experiments that provide a capability for selective sensitivity enhancements. In this article and overview and some applications of two-dimensional NMR experiments are presented. These powerful experiments are important complements to the one-dimensional experiments. As in the more sophisticated one-dimensional experiments, the two-dimensional experiments involve three distinct time periods: a preparation period, t0; an evolution period, t1; and a detection period, t2

  8. NMR and chemistry: an introduction to modern NMR spectroscopy. 3. ed.

    International Nuclear Information System (INIS)

    In the third edition of NMR and chemistry the theory of nuclear magnetic resonance is discussed. New techniques in two-dimensional NMR, imaging and high-resolution solid-state NMR are described. The applications of NMR imaging to medicine and to investigating the molecular structure of complex molecules is discussed. (UK)

  9. NMR velocity mapping and RHEO-NMR in complex liquids

    International Nuclear Information System (INIS)

    By using the NMR technique, we have determined the velocity distribution and the rate of strain in a micelle solution (cetylpyridinium chloride and sodium salicylate) below and above a critical shear rate and have studied the isotropic and stress-induced ordered nematic phases in a micelle solution CTAB/D2O in a cylindric Couette cell.

  10. A SENSITIVE NMR THERMOMETER FOR MULTINUCLEI FT NMR

    Science.gov (United States)

    A pernicious problem in multinuclei FT NMR is accurate measurement of sample temperature. This arises from several factors including widespread use of high-power decoupling, large sample tubes (with potentially large temperature gradients across the sample volume), and lack of su...

  11. NMR STUDIES OF THE STRUCTURE OF GLASS

    OpenAIRE

    Bray, P.; W.

    1982-01-01

    Over the past 25 years, wide-line Nuclear Magnetic Resonance (NMR) techniques have been used successfully to study the structure of glasses on an atomic scale [1]. Analysis of the quadrupolar structure in NMR spectra of borate glasses has yielded quantitative determinations of the relative numbers of boron atoms in various oxygen environments. After a brief discussion of the relevant as ects of NMR theory, this paper will present some of the most recent studies : B11 NMR in sodium borosilicat...

  12. High resolution NMR theory and chemical applications

    CERN Document Server

    Becker, Edwin D

    1969-01-01

    High Resolution NMR: Theory and Chemical Applications focuses on the applications of nuclear magnetic resonance (NMR), as well as chemical shifts, lattices, and couplings. The book first offers information on the theory of NMR, including nuclear spin and magnetic moment, spin lattice relaxation, line widths, saturation, quantum mechanical description of NMR, and ringing. The text then ponders on instrumentation and techniques and chemical shifts. Discussions focus on the origin of chemical shifts, reference compounds, empirical correlations of chemical shifts, modulation and phase detection,

  13. NMR analysis of plant nitrogen metabolism.

    OpenAIRE

    Mesnard, F (Fred); Ratcliffe, RG

    2005-01-01

    The analysis of primary and secondary nitrogen metabolism in plants by nuclear magnetic resonance (NMR) spectroscopy is comprehensively reviewed. NMR is a versatile analytical tool, and the combined use of (1)H, (2)H, (13)C, (14)N and (15)N NMR allows detailed investigation of the acquisition, assimilation and metabolism of nitrogen. The analysis of tissue extracts can be complemented by the in vivo NMR analysis of functioning tissues and cell suspensions, and by the application of solid stat...

  14. 63Cu and 65Cu NMR study on an amorphous Ni-Cu-P alloy

    International Nuclear Information System (INIS)

    63Cu and 65Cu NMR spectra were recorded on an amorphous Ni-Cu-P alloy using the point-by-point spin echo technique and the spin-lattice relaxation times were measured by the 180 deg pulse-spin echo and the saturation comb-spin echo sequences. The results were compared with the corresponding parameters of the 31P NMR spectrum. It was concluded that the quadrupole broadening is the dominant factor in the NMR spectra of both Cu isotopes and the Korringa-type mechanism is responsible for the nuclear spin-lattice relaxation. (author)

  15. X-ray and NMR tomography - medical equipment applied in petroleum research

    International Nuclear Information System (INIS)

    Results from short, preliminary studies are presented where X-ray and Nuclear Magnetic Resonance (NMR) tomography are applied to form pictures from drill core samples. X-ray tomography may be utilized to determine the density of dry core samples containing fluids. This method is thus well suited for flow studies in porous media. NMR tomography offers the possibility to study fundamental fluid/rock parameters like wettability, but the method has to be further developed and tested

  16. Computer Simulation of NMR Spectra.

    Science.gov (United States)

    Ellison, A.

    1983-01-01

    Describes a PASCAL computer program which provides interactive analysis and display of high-resolution nuclear magnetic resonance (NMR) spectra from spin one-half nuclei using a hard-copy or monitor. Includes general and theoretical program descriptions, program capability, and examples of its use. (Source for program/documentation is included.)…

  17. QUANTITATIVE 15N NMR SPECTROSCOPY

    Science.gov (United States)

    Line intensities in 15N NMR spectra are strongly influenced by spin-lattice and spin-spin relaxation times, relaxation mechanisms and experimental conditions. Special care has to be taken in using 15N spectra for quantitative purposes. Quantitative aspects are discussed for the 1...

  18. The physics of NMR tomography

    International Nuclear Information System (INIS)

    The nuclear magnetic resonance properties of the nuclei of atoms is a convenient means for elucidating the morphology and pathophysiology of the human body. The fundamental principles of Larmor precession are discussed from the classical as well as from the quantum mechanical point of view. In this paper, principles of NMR medical imaging and its clinical applications are discussed. (orig.)

  19. NMR analysis, protonation equilibria and decomposition kinetics of tolperisone.

    Science.gov (United States)

    Orgován, Gábor; Tihanyi, Károly; Noszál, Béla

    2009-12-01

    The rate constants of spontaneous and hydroxide-catalyzed decomposition and the tautomer-specific protonation constants of tolperisone, a classical muscle relaxant were determined. A solution NMR method without any separation techniques was elaborated to quantitate the progress of decomposition. All the rate and equilibrium constants were determined at four different temperatures and the activation parameters were calculated. The molecular mechanism of decomposition is proposed. PMID:19577875

  20. Techniques and approaches to proton NMR imaging of the head

    International Nuclear Information System (INIS)

    The next few years will undoubtedly see a refinement of proton imaging technology and a broader data base will indicate to what extent proton relaxation parameters are able to detect and characterize disease. In addition, it is likely that imaging of other nuclei (e.g. 31P, 23Na, 19F) will become a reality, although it must be stated that due to their inherently lower sensitivity to NMR detection and/or lower physiological concentration, clinical images of nuclei other than 1H will undoubtedly have a low spatial resolution and may require relatively long imaging times. Nonetheless, herein lies the exciting possibility of non-invasive metabolic or functional imaging. The realm of NMR contrast agents is just beginning to be explored, and developments in high-speed imaging indicate useful applications in cardiology. So whilst improvements in image quality can be expected, as was the case with X-ray CT, the application of NMR in medicine will diversify to yield information of a more specifically functional nature. This, together with the very low attendant biological risk, heralds a bright future for NMR in clinical diagnosis

  1. Insight into sodium silicate glass structural organization by multinuclear NMR combined with first-principles calculations

    Science.gov (United States)

    Angeli, Frédéric; Villain, Olivier; Schuller, Sophie; Ispas, Simona; Charpentier, Thibault

    2011-05-01

    Short and medium range order of silica and sodium silicate glasses have been investigated from a quantitative analysis of 29Si MAS NMR and 23Na, 17O MQMAS NMR spectra. The method described enables the extraction of the underlying 17O NMR parameter distributions of bridging oxygens (BOs) and non-bridging oxygens (NBOs), and yields site populations which are confirmed by 29Si NMR data. The extracted NMR parameter distributions and their variations with respect to the glass chemical composition can then be analyzed in terms of local structural features (bond angles and bond lengths, coordination numbers) with the help of molecular dynamics simulations combined with first-principles calculations of NMR parameters. Correlations of relevant structural parameters with 23Na, 29Si and 17O NMR interactions (isotropic chemical shift ? iso, quadrupolar coupling constant C Q and quadrupolar asymmetry parameter ? Q) are re-examined and their applicability is discussed. These data offer better insights into the structural organization of the glass network, including both chemical and topological disorder. Adding sodium to pure silica significantly diminishes the Si-O-Si bond angles and leads to a longer mean Si-O bond length with a slight decrease of the mean Na-O bond length. Moreover, the present data are in favor of a homogeneous distribution of Na around both oxygen species in the silicate network. Finally, our approach was found to be sensitive enough to investigate the effect of addition of a small quantity of molybdenum oxide (about 1 mol%) on the 17O MAS spectrum, opening new possibilities for investigating the Mo environment in silicate glasses.

  2. Broadband (1) H homodecoupled NMR experiments: Recent developments, methods and applications.

    Science.gov (United States)

    Castañar, Laura; Parella, Teodor

    2015-06-01

    In recent years, a great interest in the development of new broadband (1) H homonuclear decoupled techniques providing simplified JHH multiplet patterns has emerged again in the field of small molecule NMR. The resulting highly*-resolved (1) H NMR spectra display resonances as collapsed singlets, therefore minimizing signal overlap and expediting spectral analysis. Dr. Teodor Parella and Laura Castañar present a comprehensive compilation of the most recent advances in pure shift NMR spectroscopy, with a detailed discussion about the most relevant practical aspects in terms of pulse sequence design, selectivity, sensitivity, spectral resolution and performance. The implementation of the different reported strategies into traditional 1D and 2D NMR experiments is described and the combination with other complementary resolution-enhanced NMR techniques opens the door of the revolutionary concept of ultra high-resolved NMR spectroscopy. The usefulness of these novel techniques are illustrated for a number of challenging practical applications, such as the determination/ differentiation of very small chemical shift differences, analysis of highly crowded spectral regions, and the simplified and precise determination of relevant NMR parameters such as coupling constants, relaxation times or diffusion coefficients. PMID:25998075

  3. Measurements of Boar Spermatozoa Motility Using PFG NMR Method

    International Nuclear Information System (INIS)

    The evaluation of spermatozoa motility, viability and morphology is an essential parameter in the examination of sperm quality and in the establishment of correlations between sperm quality and fertility. Until now, assessment of sperm quality has been based on subjective evaluation of parameters, such as motility and viability, and on objective parameters, such as semen concentration and morphology abnormalities. When subjective optical microscopic evaluation was used in humans and animals, variations of 30 to 60% have been reported in the estimation of the motility parameters of the same ejaculates. To overcome this variability, different systems have been proposed such as turbidimetry, laser-Doppler spectroscopy, and photometric methods. Other accurate techniques, such as flow cytometry, which allows the evaluation of concentration, and cellulose-acetate/nitrate filter measure only a single semen parameter. The more recent track semen analysis system, based on individual spermatozoon evaluation, offers an accurate calculation of different semen parameters. Although some interesting results have already been obtained, many questions remain, which have to be answered to allow for further development in veterinary medicine, clinical fertility settings, physiological, and toxicology research activities. Pulsed field gradient nuclear magnetic resonance (PFG NMR) techniques have been presented demonstrating the potential to study flow and transport processes in complex s flow and transport processes in complex systems. By PFG NMR, the molecular displacement can be measured that occurs during a time interval D, between two consecutive magnetic field gradient pulses. In this poster we present the results of PFG-NMR obtained for a number of samples of boar spermatozoa with varying motility and discuss whether this method can be useful for fast and reliable spermatozoa motility evaluation. (author)

  4. 1H HR-MAS NMR and S180 cells: metabolite assignment and evaluation of pulse sequence

    Scientific Electronic Library Online (English)

    Aline L. de, Oliveira; Bruno César B., Martinelli; Luciano M., Lião; Flávia C., Pereira; Elisangela P., Silveira-Lacerda; Glaucia B., Alcantara.

    1135-11-01

    Full Text Available Ressonância magnética nuclear de ¹H de alta resolução com giro no ângulo mágico (HR-MAS NMR) é uma técnica empregada na avaliação de células e tecidos intactos. Entretanto, parâmetros bem estabelecidos de NMR são cruciais para a obtenção de resultados confiáveis. A fim de discutir as principais etap [...] as envolvidas na otimização das análises de HR-MAS NMR, este artigo avaliou diferentes sequências de pulsos e parâmetros de NMR usando células de sarcoma 180 (S180). O completo assinalamento dos metabólitos de S180 é também apresentado para auxiliar estudos futuros. Abstract in english High resolution magic angle spinning ¹H nuclear magnetic resonance spectroscopy (HR-MAS NMR) is a useful technique for evaluation of intact cells and tissues. However, optimal NMR parameters are crucial in obtaining reliable results. To identify the key steps for the optimization of HR-MAS NMR param [...] eters, we assessed different pulse sequences and NMR parameters using sarcoma 180 (S180) cells. A complete assignment of the metabolites of S180 is given to assist future studies.

  5. Measuring material susceptibility using NMR

    Science.gov (United States)

    SanGiorgio, Paul; Zens, Albert

    2015-06-01

    We report on a method of measuring the high-field susceptibilities of paramagnetic and diamagnetic materials using only a standard NMR system equipped with pulsed field gradients. We demonstrate the accuracy and sensitivity of the technique by measuring a series of 99.9% copper wires with diameters between 0.16 mm and 0.79 mm. We measured the volumetric susceptibility of the copper to be ? = - 9.5 ± 0.2 ·10-6 , which agrees with the literature value of pure copper, - 9.6 ·10-6 . In addition to making quantitative measurements, this technique can also be used to evaluate the effectiveness of compensation schemes used to produce "zero-susceptibility" materials needed for construction of high-resolution NMR probes.

  6. NMR metabolomics for assessment of exercise effects with mouse biofluids

    Energy Technology Data Exchange (ETDEWEB)

    Le Moyec, Laurence; Mille-Hamard, Laurence; Breuneval, Carole; Petot, Helene; Billat, Veronique L. [Universite Evry Val d' Essonne, UBIAE INSERM U902, Evry Cedex (France); Triba, Mohamed N. [Universite Paris 13, CSPBAT UMR 7244, Bobigny (France)

    2012-08-15

    Exercise modulates the metabolome in urine or blood as demonstrated previously for humans and animal models. Using nuclear magnetic resonance (NMR) metabolomics, the present study compares the metabolic consequences of an exhaustive exercise at peak velocity (Vp) and at critical velocity (Vc) on mice. Since small-volume samples (blood and urine) were collected, dilution was necessary to acquire NMR spectra. Consequently, specific processing methods were applied before statistical analysis. According to the type of exercise (control group, Vp group and Vc group), 26 male mice were divided into three groups. Mice were sacrificed 2 h after the end of exercise, and urine and blood samples were drawn from each mouse. Proton NMR spectra were acquired with urine and deproteinized blood. The NMR data were aligned with the icoshift method and normalised using the probabilistic quotient method. Finally, data were analysed with the orthogonal projection of latent-structure analysis. The spectra obtained with deproteinized blood can neither discriminate the control mice from exercised mice nor discriminate according to the duration of the exercise. With urine samples, a significant statistical model can be estimated when comparing the control mice to both groups, Vc and Vp. The best model is obtained according to the exercise duration with all mice. Taking into account the spectral regions having the highest correlations, the discriminant metabolites are allantoin, inosine and branched-chain amino acids. In conclusion, metabolomic profiles assessed with NMR are highly dependent on the exercise. These results show that urine samples are more informative than blood samples and that the duration of the exercise is a more important parameter to influence the metabolomic status than the exercise velocity. (orig.)

  7. NMR-Based Milk Metabolomics

    Directory of Open Access Journals (Sweden)

    Hanne C. Bertram

    2013-04-01

    Full Text Available Milk is a key component in infant nutrition worldwide and, in the Western parts of the world, also in adult nutrition. Milk of bovine origin is both consumed fresh and processed into a variety of dairy products including cheese, fermented milk products, and infant formula. The nutritional quality and processing capabilities of bovine milk is closely associated to milk composition. Metabolomics is ideal in the study of the low-molecular-weight compounds in milk, and this review focuses on the recent nuclear magnetic resonance (NMR-based metabolomics trends in milk research, including applications linking the milk metabolite profiling with nutritional aspects, and applications which aim to link the milk metabolite profile to various technological qualities of milk. The metabolite profiling studies encompass the identification of novel metabolites, which potentially can be used as biomarkers or as bioactive compounds. Furthermore, metabolomics applications elucidating how the differential regulated genes affects milk composition are also reported. This review will highlight the recent advances in NMR-based metabolomics on milk, as well as give a brief summary of when NMR spectroscopy can be useful for gaining a better understanding of how milk composition is linked to nutritional or quality traits.

  8. NMR-based milk metabolomics

    DEFF Research Database (Denmark)

    Sundekilde, Ulrik; Larsen, Lotte Bach

    2013-01-01

    Milk is a key component in infant nutrition worldwide and, in the Western parts of the world, also in adult nutrition. Milk of bovine origin is both consumed fresh and processed into a variety of dairy products including cheese, fermented milk products, and infant formula. The nutritional quality and processing capabilities of bovine milk is closely associated to milk composition. Metabolomics is ideal in the study of the low-molecular-weight compounds in milk, and this review focuses on the recent nuclear magnetic resonance (NMR)-based metabolomics trends in milk research, including applications linking the milk metabolite profiling with nutritional aspects, and applications which aim to link the milk metabolite profile to various technological qualities of milk. The metabolite profiling studies encompass the identification of novel metabolites, which potentially can be used as biomarkers or as bioactive compounds. Furthermore, metabolomics applications elucidating how the differential regulated genes affects milk composition are also reported. This review will highlight the recent advances in NMR-based metabolomics on milk, as well as give a brief summary of when NMR spectroscopy can be useful for gaining a better understanding of how milk composition is linked to nutritional or quality traits.

  9. Rheo-NMR of shear banded flow in wormlike micelles

    Science.gov (United States)

    Callaghan, Paul

    2008-03-01

    Rheo-NMR gives access to detailed information about the flow field generated by the device used to induce deformational flow. It also provides information about colloidal or molecular organisation and dynamics, under conditions of flow. In particular, NMR offers the possibility of measuring nuclear spin relaxation times and molecular self-diffusion coefficients, sensitive respectively to molecular brownian motions and their restrictions due to local structure. Furthermore, through the use of orientation-dependent terms in the spin interactions, such as the nuclear quadrupole or dipolar interactions, NMR permits the measurement of molecular order parameters. When combined with imaging methods, NMR in principle allows such measurements to be spatially localized, often with resolution down to a few 10s of microns In the study of shear banding phenomena in wormlike micelles, Rheo-NMR has proven of especial value, not only indicating the clear existence of shear bands, but also that they are associated with fluctuations, and sometimes, with molecular alignment. The subtlety of the correspondence (or lack of correspondence) between birefringence effects and shear banded flow has also been revealed. Recent measurements of shear-banded flow under Couette flow of the micellar system 10% w/v cetylpyridinium chloride and sodium salicylate (CPyCl/NaSal) molar ratio 2:1 in 0.5 M NaCl in ^1H2O, indicate that shear banding fluctuations are consistent with the shear stress fluctuations observed in rheological measurements. Furthermore we find a coupling between flow fluctuations in the gradient and vorticity directions. Using ^2H NMR spectroscopy on a deuterated probe molecule (n-decane) in the wormlike micellar interior, direct measurement of the shear-induced nematic phase transition is reported. More recently we have used Rheo-NMR to investigate the flow and alignment properties of worm-like micelles formed by a 5% w/w solution of the BASF difunctional block copolymer non-ionic surfactant, Pluronic P105 in water along with 4.3% w/v 1-phenylethanol-d5. A variety of shear-banding and alignment behaviours are observed, along with both stable and fluctuating flows.

  10. Development and Characterization of NMR Measurements for Polymer Gel Dosimetry

    Science.gov (United States)

    Kwong, Zachary; Whitney, Heather

    2012-03-01

    Polymer gel dosimeters are systems of water, gelatin, and monomers which form polymers upon irradiation. The gelatin matrix retains dose distribution in 3D form, facilitating truly integrated measurements of complex dose plans for radiation therapy. Polymer gels have two proton pools coupled by exchange: free solvent protons and bound polymerized macromolecular protons. Measuring magnetization transfer (MT) and relaxation affords useful insights into particle rigidity and chemical exchange effects on relaxation in polymer gels. Polymer gel dose response has been previously quantified with several techniques, most often in terms of MRI parameters, usually at field strengths of 1.5 T and below. The research described here investigates the dose response of a revised MAGIC gel dosimeter via both high-field imaging and simpler nuclear magnetic resonance (NMR) spectroscopy. This includes both transverse and longitudinal relaxation rates (R2 and R1) and quantitative MT parameters. We investigated estimating polymer molecular weight for a given applied dose using the Rouse model and R2 data from the imaging study. Finally, we began development of NMR methods for studying dose response, requiring adaption of NMR experiments to accommodate for radiation damping.

  11. Automated NMR relaxation dispersion data analysis using NESSY

    Directory of Open Access Journals (Sweden)

    Gooley Paul R

    2011-10-01

    Full Text Available Abstract Background Proteins are dynamic molecules with motions ranging from picoseconds to longer than seconds. Many protein functions, however, appear to occur on the micro to millisecond timescale and therefore there has been intense research of the importance of these motions in catalysis and molecular interactions. Nuclear Magnetic Resonance (NMR relaxation dispersion experiments are used to measure motion of discrete nuclei within the micro to millisecond timescale. Information about conformational/chemical exchange, populations of exchanging states and chemical shift differences are extracted from these experiments. To ensure these parameters are correctly extracted, accurate and careful analysis of these experiments is necessary. Results The software introduced in this article is designed for the automatic analysis of relaxation dispersion data and the extraction of the parameters mentioned above. It is written in Python for multi platform use and highest performance. Experimental data can be fitted to different models using the Levenberg-Marquardt minimization algorithm and different statistical tests can be used to select the best model. To demonstrate the functionality of this program, synthetic data as well as NMR data were analyzed. Analysis of these data including the generation of plots and color coded structures can be performed with minimal user intervention and using standard procedures that are included in the program. Conclusions NESSY is easy to use open source software to analyze NMR relaxation data. The robustness and standard procedures are demonstrated in this article.

  12. Quadrupole central transition 17O NMR spectroscopy of biological macromolecules in aqueous solution.

    Science.gov (United States)

    Zhu, Jianfeng; Wu, Gang

    2011-02-01

    We demonstrate a general nuclear magnetic resonance (NMR) spectroscopic approach in obtaining high-resolution (17)O (spin-5/2) NMR spectra for biological macromolecules in aqueous solution. This approach, termed quadrupole central transition (QCT) NMR, is based on the multiexponential relaxation properties of half-integer quadrupolar nuclei in molecules undergoing slow isotropic tumbling motion. Under such a circumstance, Redfield's relaxation theory predicts that the central transition, m(I) = +1/2 ? -1/2, can exhibit relatively long transverse relaxation time constants, thus giving rise to relatively narrow spectral lines. Using three robust protein-ligand complexes of size ranging from 65 to 240 kDa, we have obtained (17)O QCT NMR spectra with unprecedented resolution, allowing the chemical environment around the targeted oxygen atoms to be directly probed for the first time. The new QCT approach increases the size limit of molecular systems previously attainable by solution (17)O NMR by nearly 3 orders of magnitude (1000-fold). We have also shown that, when both quadrupole and shielding anisotropy interactions are operative, (17)O QCT NMR spectra display an analogous transverse relaxation optimized spectroscopy type behavior in that the condition for optimal resolution depends on the applied magnetic field. We conclude that, with the currently available moderate and ultrahigh magnetic fields (14 T and higher), this (17)O QCT NMR approach is applicable to a wide variety of biological macromolecules. The new (17)O NMR parameters so obtained for biological molecules are complementary to those obtained from (1)H, (13)C, and (15)N NMR studies. PMID:21175170

  13. Pseudogap in Fe2VGa: NMR evidence

    Science.gov (United States)

    Lue, C. S.; Ross, Joseph H.

    2001-02-01

    We report the results of a 51V and 69Ga nuclear magnetic resonance (NMR) study of Fe2VGa at temperatures between 4 and 450 K. The presence of magnetic antisite defects is deduced from the NMR linewidth, which displays a Curie-law temperature dependence. The absence of associated NMR shifts indicates the material to be intrinsically nonmagnetic. At low temperatures the NMR spin-lattice relaxation rate exhibits Korringa behavior, indicating a small carrier density at the Fermi level. At elevated temperatures, the Knight shifts and NMR relaxation rates go over to a thermally activated response, a semiconductor-like behavior. These results are consistent with pseudogap features identified by recent band structure calculations. The Fermi level density of states deduced from NMR is considerably smaller than given by the specific heat coefficient, ?. The electronic properties are compared to the isostructural semimetal Fe2VAl.

  14. Transverse NMR relaxation as a probe of mesoscopic structure

    CERN Document Server

    Kiselev, V G; Kiselev, Valerij G.; Novikov, Dmitry S.

    2002-01-01

    We show that transverse NMR signal relaxation averaged over a macroscopic volume is extremely sensitive to structure of mesoscopic paramagnetic inhomogeneities. Such a sensitivity is proposed as a novel kind of contrast in the NMR measurements. We model the medium by a suspension of arbitrary shaped mesoscopic paramagnetic objects, and find transverse relaxation without adjustable parameters in the case when the dephasing effect of an individual object is small. Results indicate a strong relaxation rate dependence on the shape of the objects. As a major application we consider transverse spin relaxation in the whole blood, for which our theory agrees well with experiments and Monte-Carlo simulations. Applications to a wide range of problems in complex systems (porous media, biological systems, diffusion limited reaction rates) are discussed.

  15. Antiferro multipolar ordering and it's identification by NMR experiment

    International Nuclear Information System (INIS)

    The antiferro-ordering of multipolar moments often plays important roles in the low temperature phase transition of f-electron systems. The splitting of NMR spectra, which is analyzed in terms of the invariant hyperfine coupling between the nuclear spin and the multipolar moments of magnetic ions, gives important information about the multipolar ordering. Experimental and theoretical studies on CeB6 and NpO2 are presented as typical examples. The study on the low temperature phase of PrFe4P12, whose nature has been controversial, are reviewed. It was concluded that it has an antiferro order with the order-parameter characterized by the identity representation of the point group. The large anisotropy of NMR splitting in the magnetic field direction dependence suggests important roles of moments with higher ranks in PrFe4P12. (author)

  16. Time domain NMR applied to food products

    OpenAIRE

    Duynhoven, J., van; Voda, A.; Witek, M.M.; As, H (Henk) van

    2010-01-01

    Time-domain NMR is being used throughout all areas of food science and technology. A wide range of one- and two-dimensional relaxometric and diffusometric applications have been implemented on cost-effective, robust and easy-to-use benchtop NMR equipment. Time-domain NMR applications do not only cover research and development but also quality and process control in the food supply chain. Here the opportunity to further downsize and tailor equipment has allowed for “mobile” sensor applicat...

  17. High-resolution NMR with hybrid magnets

    International Nuclear Information System (INIS)

    Hybrid magnets can achieve substantially higher fields than those available in superconducting magnets, but their spatial homogeneity and temporal stability are unacceptable for high-resolution NMR. To overcome this disadvantage, various methods have been examined. The detection of intermolecular zero-quantum coherences is proposed for the removable of the effects of inhomogeneity and drift. Ferromagnetic inserts combined with feedback control of power supply and NMR reference deconvolution can be used to obtain well-resolved solid-state NMR. In this report, two methods for compensating effect of field fluctuation were examined to attain high-resolution NMR spectra with a hybrid magnet. In one method, time dependence of electromotive force induced for a pickup coil attached near a sample was measured synchronously with acquisition of NMR. Observed voltage across the picked coil was converted to field fluctuation data, which was used to deconvolute NMR signals. This method was applied to 79Br Magic Angle Spinning (MAS) NMR or KBr under a 30T magnetic field. More precise reference signal was required for NMR spectra of liquids because of sharp lines. The other method was developed by using the phase angle of NMR spectrum caused by field fluctuation. Trial experiment by the latter method was performed with the two nuclei probes attaching a coil artificially generating field fluctuation. The sample used in this experiment was a mixture of a small amount of ethynt was a mixture of a small amount of ethyl benzene in benzene d6. (Y. Kazumata)

  18. NMR studies of isotopically labeled RNA

    Energy Technology Data Exchange (ETDEWEB)

    Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

    1994-12-01

    In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

  19. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sorland, Geir Humborstad

    2014-01-01

    Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with backgro

  20. Access to NMR Spectroscopy for Two-Year College Students: The NMR Site at Trinity University

    Science.gov (United States)

    Mills, Nancy S.; Shanklin, Michael

    2011-01-01

    Students at two-year colleges and small four-year colleges have often obtained their exposure to NMR spectroscopy through "canned" spectra because the cost of an NMR spectrometer, particularly a high-field spectrometer, is prohibitive in these environments. This article describes the design of a NMR site at Trinity University in which spectral…

  1. Phenomenological simulation and density functional theory prediction of 57 Fe Mössbauer parameters: application to magnetically coupled diiron proteins

    Science.gov (United States)

    Rodriguez, Jorge H.

    2013-04-01

    The use of phenomenological spin Hamiltonians and of spin density functional theory for the analysis and interpretation of Mössbauer spectra of antiferromagnetic or ferromagnetic diiron centers is briefly discussed. The spectroscopic parameters of the hydroxylase component of methane monooxygenase (MMOH), an enzyme that catalyzes the conversion of methane to methanol, have been studied. In its reduced diferrous state (MMOH Red ) the enzyme displays 57Fe Mössbauer and EPR parameters characteristic of two ferromagnetically coupled high spin ferrous ions. However, Mössbauer spectra recorded for MMOH Red from two different bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, display slightly different electric quadrupole splittings (? E Q ) in apparent contradiction to their essentially identical active site crystallographic structures and biochemical functions. Herein, the Mössbauer spectral parameters of MMOH Red have been predicted and studied via spin density functional theory. The somewhat different ? E Q recorded for the two bacteria have been traced to the relative position of an essentially unbound water molecule within their diiron active sites. It is shown that the presence or absence of the unbound water molecule mainly affects the electric field gradient at only one iron ion of the binuclear active sites.

  2. Hydrogeological Parameter Estimation Using Low-Field Proton Nuclear Magnetic Resonance: Lessons from the Laboratory

    Science.gov (United States)

    Keating, K.; Falzone, S.; Osterman, G. K.; Wallace, D. S.

    2014-12-01

    Geophysical methods can provide a non-invasive method for estimating spatial variability in hydrogeological parameters such as water content, hydraulic conductivity, and matric potential. Proton nuclear magnetic resonance (NMR) is unique amongst geophysical methods in that it is directly sensitive to water, via the initial signal magnitude, and thus provides a robust estimate of water content. In addition, the NMR relaxation time is sensitive to pore geometry, allowing it to be used to predict the hydraulic conductivity and to determine water retention curves. While NMR measurements are considered a mature technology in the petroleum industry, the strength of NMR data for hydrogeophysical studies is still being realized. The major ongoing challenge is to generate a functional mapping of the relationship between pore geometry and relaxation time, while accounting for pore chemistry. In our research, we are developing and refining quantitative petrophysical models that relate NMR parameters to hydrogeological parameters. Here we present laboratory measurements that highlight our recent successes in using NMR measurements to estimate several hydrogeological parameters and overcome the limitations of the standard petrophysical models. We examine these relationships by collecting NMR measurements on synthetic and geologic materials with carefully controlled or quantified pore properties, i.e., pore surface-area-to-volume ratio (S/V), pore size and surface iron concentration, and relate these variables to hydrogeological parameters including water content, hydraulic conductivity, and/or the water retention curve. Our major results include developing a relationship between the NMR relaxation times and water saturation across diverse chemical environments, and showing that for materials with rough surfaces, S/V, and not average pore diameter, is the relevant parameter in the interpretation of NMR data. Despite the many challenges in interpreting the measurements, valuable information about hydrogeological parameters can be obtained from NMR relaxation data, and we conclude by outlining pathways for improving the interpretation of NMR data for hydrogeophysical investigations.

  3. The eNMR platform for structural biology

    OpenAIRE

    Bonvin, A. M. J. J.; Rosato, A.; Wassenaar, T. A.

    2010-01-01

    The e-NMR project is a European cooperation initiative that aims at providing the bio-NMR user community with a software platform integrating and streamlining the computational approaches necessary for the analysis of bio-NMR data. The e-NMR platform is based on a Grid computational infrastructure. A main focus of the current implementation of the e-NMR platform is on streamlining structure determination protocols. Indeed, to facilitate the use of NMR spectroscopy in t...

  4. An Inexpensive High-Throughput NMR Tube Cleaning Apparatus

    OpenAIRE

    Zhang, Bo; Hodgson, James; Hancock, Walter; Powers, Robert

    2011-01-01

    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 (~$2 to $8/tube), using commercial NMR tube cleaners (~$15K) or abandoning NMR tubes for flow probe technology (~$75K). Instead, we describe a relatively inexpensive (~$400) and easily constructed apparatus that can clean 180 NMR tubes an hour while using a modest amount of solvent. The a...

  5. Synthesis and carbon-13 NMR studies of liquid crystals

    Science.gov (United States)

    Sun, Hong

    2000-08-01

    The orientation of different segments of 4'-cyanophenyl 4-heptylbenzoate (7CPB) has been investigated using 13C NMR. The method of proton encoded local field (PELF) spectroscopy was used in combination with off-magic-angle spinning (OMAS) of the sample. High-resolution 2D spectra were obtained and the order parameters were calculated from the spectra. Linear relationships between the obtained order parameters and anisotropic chemical shifts determined by 1D 13C NMR were established and semi-empirical parameters were obtained. A 1:2 mixture of 7CPB and its chain-perfluorinated analog (7PFCPB) shows interesting phase behavior with changing of temperature. The mixture was studied by the use of 13C NMR and polarizing optical microscopy. The order parameters of 7CPB in the smectic A phase of the mixture were calculated using the semi-empirical parameters obtained by the 2D NMR method. Eight series of liquid crystals containing an electron- donating group at one end of a conjugated system and an electron-withdrawing group at the other end have been synthesized. The electron-donating group is 4- n-alkylpiperazinyl group, the electron- withdrawing group is nitro group and the conjugated system is diphenyldiazene with zero, one or two substituents on the phenyl rings. The substituents are -F, -Cl, and -CH3. Two series of compounds with cyano group as electron-withdrawing group were also synthesized. Most of the compounds synthesized are nematogenic and exhibit rather broad liquid crystalline ranges. The effects of the lateral substituents on the optical absorption and phase transition temperatures are correlated with their nature and position of substitution. Birefringence, dielectric anisotropy, elastic constant ratio and rise time of the liquid crystals were carried out using 10 wt% LC mixtures in E7. It has been found that lateral substituents have subtle effects on the properties. The presence of lateral substituents depresses melting points and clearing points of the liquid crystals. All the liquid crystals synthesized in this work have relatively large values of birefiringence, although the dielectric anisotropy values were not as high as desired. The incorporation of a fluorine atom onto the position neighboring the nitro group enhances the conjugation of the push-pull system and liquid crystals with better physical properties were obtained.

  6. Design of a low cost NMR Spectrometer

    Science.gov (United States)

    Hollos, Stefan; Hollos, Richard

    2000-09-01

    We describe the design of a small desktop nuclear magnetic resonance (NMR) spectrometer suitable for use as a teaching device. The design goal was to create the simplest, most low cost NMR spectrometer possible. The circuitry is designed from the ground up using common off the shelf components. A strong magnetic field is produced by a pair of rare earth permanent magnets.

  7. An Inversion Recovery NMR Kinetics Experiment

    Science.gov (United States)

    Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

    2011-01-01

    A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this…

  8. Early history of NMR at Los Alamos

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy has developed into an important research tool in chemistry. More recently, NMR imaging and in vivo spectroscopy promise to produce a revolution in medicine and biochemistry. Early experiments at Los Alamos led to DOE programs involving stable isotopes of importance to biology and to medicine. These events are briefly recounted. 2 refs

  9. NMR Spectroscopy and Its Value: A Primer

    Science.gov (United States)

    Veeraraghavan, Sudha

    2008-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is widely used by chemists. Furthermore, the use of NMR spectroscopy to solve structures of macromolecules or to examine protein-ligand interactions is popular. Yet, few students entering graduate education in biological sciences have been introduced to this method or its utility. Over the last six…

  10. 2D NMR studies of biomolecules

    International Nuclear Information System (INIS)

    The work described in this thesis comprises two related subjects. The first part describes methods to derive high-resolution structures of proteins in solution using two-dimensional (2-D) NMR. The second part describes 2-D NMR studies on the interaction between proteins and DNA. (author). 261 refs.; 52 figs.; 23 tabs

  11. Bituminous ore characterization by integrating low-field NMR with density and particle size distribution measurements

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) imaging is often used to determine the content of oil sands ore. However, it is difficult for current NMR spectrometers to differentiate bitumen spectra and clay-bound water signals. This paper provided details of a novel method for determining the fluid and solids content of oil sands using low-field NMR. The method involved the integration of a density measurement to an NMR algorithm combined with laboratory oil sands evaluations. Thawed raw oil sands samples were weighed and injected with nitrogen to calculate the gas occupied volume. An independent solid content estimate was made by measuring both the weight and the bulk density of an ore sample. The sample was then placed into an NMR spectrometer and exposed to different CPMG parameters. Bitumen and water content were determined using the NMR algorithm. Particle size distribution analysis using Dean-Stark extraction showed that the method correlated with the fast relaxation components of water spectra in both oil sands and water-saturated sand extracted from the ore. A vacuum saturation step was then followed by a centrifugal desaturation of the sand to irreducible saturation. The method was then tested with samples of 4 Athabasca oil sands. It was concluded that use of the new method will accelerate core analysis times

  12. 1H-NMR urinalysis

    International Nuclear Information System (INIS)

    In an effort to examine the usefulness of 1H-nuclear magnetic resonance (NMR) urinalysis in the diagnosis of congenital metabolic disorders, 70 kinds of urinary metabolites were analysed in relation to the diagnosis of inborn errors of amino acid and organic acid disorders. Homogated decoupling (HMG) method failed to analyze six metabolites within the undetectable range. When non-decoupling method (NON), in which the materials are dissolved in dimethyl sulfoxide, was used, the identification of signals became possible. The combination of HMG and NON methods was, therefore, considered to identify all of the metabolites. When the urine samples, which were obtained from patients with hyperglycerolemia, hyperornithinemia, glutaric acidemia type II, or glycerol kinase deficiency, were analysed by using both HMG and NON methods, abnormally increased urinary metabolites were detected. 1H-NMR urinalysis, if used in the combination of HMG and NON methods, may allow simultanenous screening of inborn errors of metabolism of amino acid and organic acid disorders. (Namekawa, K.)

  13. NMR studies of molecules in liquid crystals and graphite

    Science.gov (United States)

    Rosen, M. E.

    1992-06-01

    NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.

  14. Image reconstruction by NMR Fresnel diffractive imaging technique

    International Nuclear Information System (INIS)

    A new approach to MR angiography, the NMR diffractive imaging technique, has been investigated. The expression for NMR signals obtained in the NMR diffractive imaging technique is similar to the equation for Fresnel diffraction in light waves or sound waves. Therefore, it is possible to reconstruct an image focusing on any plane in the depth direction from data scanned two-dimensionally by changing an imaging parameter in the reconstruction step. To support this imaging technique, a coil system composed of six coils was designed. Experiments were performed using an ultra-low-field MRI scanner to acquire two-dimensional data in the proposed technique. Even though blurred images outside the focus are superimposed on the image in the focal plane, the three-dimensional distribution of the object can be recognized by moving the focal plane in the depth direction. To obtain supplemental information for the object, acquiring images from different angles is helpful for recognizing the spatial distribution of the object more precisely. Although the image obtained contains blurred images outside the focus the proposed imaging technique is expected to be useful in MR fast angiography. (author)

  15. Carbon-13 NMR spectroscopy of biological systems

    CERN Document Server

    Beckmann, Nicolau

    1995-01-01

    This book is intended to provide an in-depth understanding of 13C NMR as a tool in biological research. 13C NMR has provided unique information concerning complex biological systems, from proteins and nucleic acids to animals and humans. The subjects addressed include multidimensional heteronuclear techniques for structural studies of molecules in the liquid and solid states, the investigation of interactions in model membranes, the elucidation of metabolic pathwaysin vitro and in vivo on animals, and noninvasive metabolic studies performed on humans. The book is a unique mix of NMR methods and biological applications which makes it a convenient reference for those interested in research in this interdisciplinary area of physics, chemistry, biology, and medicine.Key Features* An interdisciplinary text with emphasis on both 13C NMR methodology and the relevant biological and biomedical issues* State-of-the-art 13C NMR techniques are described; Whenever possible, their advantages over other approaches are empha...

  16. NMR and MRI apparatus and method

    Science.gov (United States)

    Clarke, John; Kelso, Nathan; Lee, SeungKyun; Moessle, Michael; Myers, Whittier; McDermott, Robert; ten Haken, Bernard; Pines, Alexander; Trabesinger, Andreas

    2007-03-06

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  17. Solid-state 17O NMR of pharmaceutical compounds: salicylic acid and aspirin.

    Science.gov (United States)

    Kong, Xianqi; Shan, Melissa; Terskikh, Victor; Hung, Ivan; Gan, Zhehong; Wu, Gang

    2013-08-22

    We report solid-state NMR characterization of the (17)O quadrupole coupling (QC) and chemical shift (CS) tensors in five site-specifically (17)O-labeled samples of salicylic acid and o-acetylsalicylic acid (Aspirin). High-quality (17)O NMR spectra were obtained for these important pharmaceutical compounds under both static and magic angle spinning (MAS) conditions at two magnetic fields, 14.0 and 21.1 T. A total of 14 (17)O QC and CS tensors were experimentally determined for the seven oxygen sites in salicylic acid and Aspirin. Although both salicylic acid and Aspirin form hydrogen bonded cyclic dimers in the solid state, we found that the potential curves for the concerted double proton transfer in these two compounds are significantly different. In particular, while the double-well potential curve in Aspirin is nearly symmetrical, it is highly asymmetrical in salicylic acid. This difference results in quite different temperature dependencies in (17)O MAS spectra of the two compounds. A careful analysis of variable-temperature (17)O MAS NMR spectra of Aspirin allowed us to obtain the energy asymmetry (?E) of the double-well potential, ?E = 3.0 ± 0.5 kJ/mol. We were also able to determine a lower limit of ?E for salicylic acid, ?E > 10 kJ/mol. These asymmetrical features in potential energy curves were confirmed by plane-wave DFT computations, which yielded ?E = 3.7 and 17.8 kJ/mol for Aspirin and salicylic acid, respectively. To complement the solid-state (17)O NMR data, we also obtained solid-state (1)H and (13)C NMR spectra for salicylic acid and Aspirin. Using experimental NMR parameters obtained for all magnetic nuclei present in salicylic acid and Aspirin, we found that plane-wave DFT computations can produce highly accurate NMR parameters in well-defined crystalline organic compounds. PMID:23879687

  18. Variable-temperature 17O NMR studies allow quantitative evaluation of molecular dynamics in organic solids.

    Science.gov (United States)

    Kong, Xianqi; O'Dell, Luke A; Terskikh, Victor; Ye, Eric; Wang, Ruiyao; Wu, Gang

    2012-09-01

    We report a comprehensive variable-temperature solid-state (17)O NMR study of three (17)O-labeled crystalline sulfonic acids: 2-aminoethane-1-sulfonic acid (taurine, T), 3-aminopropane-1-sulfonic acid (homotaurine, HT), and 4-aminobutane-1-sulfonic acid (ABSA). In the solid state, all three compounds exist as zwitterionic structures, NH(3)(+)-R-SO(3)(-), in which the SO(3)(-) group is involved in various degrees of O···H-N hydrogen bonding. High-quality (17)O NMR spectra have been obtained for all three compounds under both static and magic angle spinning (MAS) conditions at 21.1 T, allowing the complete set of (17)O NMR tensor parameters to be measured. Assignment of the observed (17)O NMR parameters to the correct oxygen sites in the crystal lattice was achieved with the aid of DFT calculations. By modeling the temperature dependence of (17)O NMR powder line shapes, we have not only confirmed that the SO(3)(-) groups in these compounds undergo a 3-fold rotational jump mechanism but also extracted the corresponding jump rates (10(2)-10(5) s(-1)) and the associated activation energies (E(a)) for this process (E(a) = 48 ± 7, 42 ± 3, and 45 ± 1 kJ mol(-1) for T, HT, and ABSA, respectively). This is the first time that SO(3)(-) rotational dynamics have been directly probed by solid-state (17)O NMR. Using the experimental activation energies for SO(3)(-) rotation, we were able to evaluate quantitatively the total hydrogen bond energy that each SO(3)(-) group is involved in within the crystal lattice. The activation energies also correlate with calculated rotational energy barriers. This work provides a clear illustration of the utility of solid-state (17)O NMR in quantifying dynamic processes occurring in organic solids. Similar studies applied to selectively (17)O-labeled biomolecules would appear to be very feasible. PMID:22877150

  19. Median Modified Wiener Filter for nonlinear adaptive spatial denoising of protein NMR multidimensional spectra

    Science.gov (United States)

    Cannistraci, Carlo Vittorio; Abbas, Ahmed; Gao, Xin

    2015-01-01

    Denoising multidimensional NMR-spectra is a fundamental step in NMR protein structure determination. The state-of-the-art method uses wavelet-denoising, which may suffer when applied to non-stationary signals affected by Gaussian-white-noise mixed with strong impulsive artifacts, like those in multi-dimensional NMR-spectra. Regrettably, Wavelet's performance depends on a combinatorial search of wavelet shapes and parameters; and multi-dimensional extension of wavelet-denoising is highly non-trivial, which hampers its application to multidimensional NMR-spectra. Here, we endorse a diverse philosophy of denoising NMR-spectra: less is more! We consider spatial filters that have only one parameter to tune: the window-size. We propose, for the first time, the 3D extension of the median-modified-Wiener-filter (MMWF), an adaptive variant of the median-filter, and also its novel variation named MMWF*. We test the proposed filters and the Wiener-filter, an adaptive variant of the mean-filter, on a benchmark set that contains 16 two-dimensional and three-dimensional NMR-spectra extracted from eight proteins. Our results demonstrate that the adaptive spatial filters significantly outperform their non-adaptive versions. The performance of the new MMWF* on 2D/3D-spectra is even better than wavelet-denoising. Noticeably, MMWF* produces stable high performance almost invariant for diverse window-size settings: this signifies a consistent advantage in the implementation of automatic pipelines for protein NMR-spectra analysis. PMID:25619991

  20. Median Modified Wiener Filter for nonlinear adaptive spatial denoising of protein NMR multidimensional spectra

    KAUST Repository

    Cannistraci, Carlo Vittorio

    2015-01-26

    Denoising multidimensional NMR-spectra is a fundamental step in NMR protein structure determination. The state-of-the-art method uses wavelet-denoising, which may suffer when applied to non-stationary signals affected by Gaussian-white-noise mixed with strong impulsive artifacts, like those in multi-dimensional NMR-spectra. Regrettably, Wavelet\\'s performance depends on a combinatorial search of wavelet shapes and parameters; and multi-dimensional extension of wavelet-denoising is highly non-trivial, which hampers its application to multidimensional NMR-spectra. Here, we endorse a diverse philosophy of denoising NMR-spectra: less is more! We consider spatial filters that have only one parameter to tune: the window-size. We propose, for the first time, the 3D extension of the median-modified-Wiener-filter (MMWF), an adaptive variant of the median-filter, and also its novel variation named MMWF*. We test the proposed filters and the Wiener-filter, an adaptive variant of the mean-filter, on a benchmark set that contains 16 two-dimensional and three-dimensional NMR-spectra extracted from eight proteins. Our results demonstrate that the adaptive spatial filters significantly outperform their non-adaptive versions. The performance of the new MMWF* on 2D/3D-spectra is even better than wavelet-denoising. Noticeably, MMWF* produces stable high performance almost invariant for diverse window-size settings: this signifies a consistent advantage in the implementation of automatic pipelines for protein NMR-spectra analysis.

  1. A HTS dc SQUID-NMR: fabrication of the SQUID and application to low-field NMR for fruit quality detection

    Science.gov (United States)

    Isingizwe Nturambirwe, J. Frédéric; Perold, Willem J.; Opara, Linus U.

    2014-06-01

    Superconducting Quantum Interference Devices (SQUIDs) have made the detection of low-field (LF) and ultra-low field nuclear magnetic resonance (ULF-NMR) a reality. The latter has been proven to be a potential tool for non-destructive quality testing of horticultural products, amongst many other applications. High-Temperature Superconductor (HTS) dc SQUIDS are likely to allow for the development of not only low-cost NMR systems but also prototypes that are mobile and easily maintainable. A HTS dc SQUID was manufactured on an YBCO thin film, using a novel laser based lithography method. The lithography was implemented by a new laser system developed in-house, as a model of low-cost lithography systems. The junctions of the dc SQUID were tested and displayed normal I-V characteristics in the acceptable range for the application. In order to determine the viability of low-field NMR for non-destructive quality measurement of horticultural products, a commercial HTS dc SQUID-NMR system was used to measure quality parameters of banana during ripening. The trend of color change and sugar increase of the banana during ripening were the most highly correlated attributes to the SQUID-NMR measured parameter, average T1 (spin-lattice relaxation time). Further studies were done, that involved processing of the NMR signal into relaxation time resolved spectra. A spectral signature of banana was obtained, where each peak is a T1 value corresponding to a proton pool, and is reported here. These results will potentially lead to deeper understanding of the quality of the samples under study.

  2. NMR study of the ma?etic metals cobalt and nickel in the paramagnetic and ferromagnetic states

    International Nuclear Information System (INIS)

    Results of NMR measurements in the 3d - electron transition metals nickel and cobalt are presented. Measurements were performed in the paramagnetic and ferromagnetic states, as close as possible, experimentally to the Curie transition temperature Tsub(c). It is shown that NMR is a powerful tool to study the behavior of magnetic metals. The developed experimental technique enables measurements in an extended temperature range in metals with strongly temperature dependent parameters. (B.G.)

  3. Effect of Secondary Echo Signals in Spin-Systems with a Large Inhomogeneous Broadening of NMR Line

    OpenAIRE

    Chigvinadze, J. G.; Mamniashvili, G. I.; Sharimanov, Yu G.

    2003-01-01

    The possibility of comparatively simple and fast determination of characteristic relaxation parameters T1, T2 and T3 for nuclear spin-systems with strong Larmor and Rabi inhomogeneous broadenings of NMR lines using the secondary echo signal effect was experimentally shown. Resides, this method gives opportunity to obtain a valuable infomation on the inhomogeneous NMR broadening which reflects the character of magnetic field microscopic destribution in such systems, as exampl...

  4. NMR spectroscopic characterization of ?-cyclodextrin inclusion complex with vanillin

    International Nuclear Information System (INIS)

    The inclusion of vanillin by ?-cyclodextrin was investigated by 1H NMR. The continuous variation technique was used to evidence the formation of soluble 1:1 complex in aqueous solution. The association constant of vanillin with ?-cyclodextrin has been obtained at 298 K by fitting the experimental chemical shifts differences, ??obs ?free - ?obs of the observed guest and host protons, with a non-linear regression method. Besides the effective association constant, the fitting procedure allows a precise determination of all chemical shift parameters characterizing the pure complex. They can by used for an analysis of the geometry of the molecular complex in solution.

  5. Assessment of structural changes of human teeth by low-field nuclear magnetic resonance (NMR)

    International Nuclear Information System (INIS)

    A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in vitro. The technique involves spin–spin relaxation measurement and inversion spin–spin spectral analysis methods. The spin–spin relaxation decay curve is converted into a T2 distribution spectrum by a sum of single exponential decays. The NMR spectra from the extracted dentin-portion-only and dental pulp-cells-only were compared with the whole extracted teeth spectra, for the dentin and pulp peak assignments. While dentin and pulp are highly significant parameters in determining tooth quality, variations in these parameters with age can be used as an effective tool for estimating tooth quality. Here we propose an NMR calibration method—the ratio of the amount of dentin to the amount of pulp obtained from NMR T2 distribution spectra can be used for measuring the age-related structural changes in teeth while eliminating any variations in size of teeth. Eight teeth (third molars) extracted from humans, aged among 17–67 years old, were tested in this study. It is found that the intensity ratio of dentin to pulp sensitively changes from 0.48 to 3.2 approaching a linear growth with age. This indicates that age-related structural changes in human teeth can be detected using the low-field NMR technique

  6. CoNSEnsX: an ensemble view of protein structures and NMR-derived experimental data

    Directory of Open Access Journals (Sweden)

    Perczel András

    2010-10-01

    Full Text Available Abstract Background In conjunction with the recognition of the functional role of internal dynamics of proteins at various timescales, there is an emerging use of dynamic structural ensembles instead of individual conformers. These ensembles are usually substantially more diverse than conventional NMR ensembles and eliminate the expectation that a single conformer should fulfill all NMR parameters originating from 1016 - 1017 molecules in the sample tube. Thus, the accuracy of dynamic conformational ensembles should be evaluated differently to that of single conformers. Results We constructed the web application CoNSEnsX (Consistency of NMR-derived Structural Ensembles with eXperimental data allowing fast, simple and convenient assessment of the correspondence of the ensemble as a whole with diverse independent NMR parameters available. We have chosen different ensembles of three proteins, human ubiquitin, a small protease inhibitor and a disordered subunit of cGMP phosphodiesterase 5/6 for detailed evaluation and demonstration of the capabilities of the CoNSEnsX approach. Conclusions Our results present a new conceptual method for the evaluation of dynamic conformational ensembles resulting from NMR structure determination. The designed CoNSEnsX approach gives a complete evaluation of these ensembles and is freely available as a web service at http://consensx.chem.elte.hu.

  7. High-resolution NMR imaging of mandibular joints, with special emphasis on soft tissue imaging

    International Nuclear Information System (INIS)

    NMR imaging is the technique finally allowing good imaging of the soft tissue parts of the mandibular joint without recourse to surgery or ionizing radiation. Surface coils yield high-resolution images, and proper selection of tomographic parameters achieves excellent tissue contrast data without the use of positive or negative contrast media. (orig.)

  8. Stereochemistry of tropane N-oxide derivatives studied by experimental and theoretical NMR.

    Czech Academy of Sciences Publication Activity Database

    Pohl, Radek; Dra?ínský, Martin; Slav?tínská, Lenka; Bud?šínský, Miloš

    Frankfurt am Main : Cuvillier Verlag Göttingen, 2011. s. 279-279. [EUROMAR 2011. Magnetic Resonance Conference. 21.08.2011-25.08.2011, Frankfurt am Main] Institutional research plan: CEZ:AV0Z40550506 Keywords : stereochemistry * calculation of the NMR parameters * DFT GIAO Subject RIV: CC - Organic Chemistry

  9. Clinical experience with NMR imaging

    International Nuclear Information System (INIS)

    The book presents results and experience obtained by about 2.400 examinations made in the Grosshadern clinical centre. All examinations have been made with a 1.5 T nuclear tomograph of Siemens AG (Magnetom), with magnetic inductions of 0.35 T and 1.0 T. Methodological problems and problems of principle today still make it difficult to determine the relaxation times, but the authors nevertheless decided to also include this kind of data in the material of the various chapters. The readers should take this information as a line of orientation for comparison rather than as established data, all the more since the development towards higher magnetic inductions will certainly mean longer T1 times. The various chapters dealing with the individual body regions or organs each present information on an optimized examination technique, which is the result of scientifically based, applied research work with NMR imaging device. The developments in equipment have led to shorter echo times for enhanced T1 pulse sequences, and to longer echo times for enhanced T2 pulse sequences. The pulse sequences given indicate optimum conditions with regard to sensitivity and specificity of the technique. The enhanced clinical application of NMR imaging over the last few years acccumulated and well improved knowledge of the diagnostic potentials of the method, and of the problems involved. However, the amount of information available today does not yet allow a coon available today does not yet allow a comprehensive evaluation of the method to be made, so that the material presented in this book is meant as a presentation of the current state of the art; with further developments to be expected. With 1061 figs., 81 tabs

  10. NMR spectroscopy: Application to metabolic research

    International Nuclear Information System (INIS)

    The aim of this chapter is to demonstrate the considerable clinical potential of NMR spectroscopy. In reviewing the course of imaging and spectroscopy over the past decade one sees that imaging has moved from visualisation of the internal structure of various fruits to high definition neurological and body imaging, where pixel sizes (x 0.3 mm/sup 2/) approach those obtainable in high resolution CT. However, the clinical superiority of NMR imaging in identifying pathological information is controversial: conversely, the interpretation of NMR spectroscopy, especially /sup 31/P, is well understood. Few in vivo clinical studies have been performed, principally due to the low availability of large magnets of suitable field strength and the formidable difficulties of defining precise volumes within a patient from which spectra may be taken. In reviewing the field of NMR spectroscopy it will be shown that these obstacles can be overcome and that much of the groundwork on animal studies may be readily transferred to the clinical environment. Many clinical spectroscopy systems have come into operation over the past year and a large increase in human studies is expected. In this review the major organ/tissue systems examined using NMR spectroscopy are discussed. Many of these studies have been carried out on animals, but the extrapolation to in vivo clinical studies is clearly apparent. First, however, it is profitable to review briefly how we obtain an NMR spectrum from an are how we obtain an NMR spectrum from an area of interest

  11. Scalar operators in solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Boqin

    1991-11-01

    Selectivity and resolution of solid-state NMR spectra are determined by dispersion of local magnetic fields originating from relaxation effects and orientation-dependent resonant frequencies of spin nuclei. Theoretically, the orientation-dependent resonant frequencies can be represented by a set of irreducible tensors. Among these tensors, only zero rank tensors (scalar operators) are capable of providing high resolution NMR spectra. This thesis presents a series of new developments in high resolution solid-state NMR concerning the reconstruction of various scalar operators motion in solid C{sub 60} is analyzed.

  12. Introduction to some basic aspects of NMR

    International Nuclear Information System (INIS)

    The principal interactions are reviewed that are experienced by nuclear spins making magnetic resonance feasible and which disturb it in a way that gives access to the properties of bulk matter. The interactions leading to NMR include Zeeman interaction, dipole-dipole interactions, and exchange interactions. Spin-lattice relaxation relevant to NMR is revisited next. It is followed by an overview of spin temperature. Finally, the care of periodic Hamiltonian is discussed in detail as another contribution to NMR. (R.P.) 48 refs., 12 figs

  13. Graphical programming for pulse automated NMR experiments

    Energy Technology Data Exchange (ETDEWEB)

    Belmonte, S.B. [Universidade do Estado, Rio de Janeiro, RJ (Brazil); Oliveira, I.S.; Guimaraes, A.P. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1999-01-01

    We describe a software program designed to control a broadband pulse Nuclear Magnetic Resonance (NMR) spectrometer used in zero-field NMR studies of magnetic metals. The software is written in the graphical language LabVIEW. This type of programming allows modifications and the inclusion of new routines to be easily made by the non-specialist, without changing the basic structure of the program. The program corrects for differences in the gain of the two acquisition channels [U (phase) and V (quadrature)], and automatic baseline subtraction. We present examples of measurements of NMR spectra, spin-echo decay (T{sub 2}), and quadrupolar oscillations, performed in magnetic intermetallic compounds. (author)

  14. MAS NMR of HIV-1 protein assemblies

    Science.gov (United States)

    Suiter, Christopher L.; Quinn, Caitlin M.; Lu, Manman; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana

    2015-04-01

    The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates.

  15. Probing porous media with gas diffusion NMR

    Science.gov (United States)

    Mair, R. W.; Wong, G. P.; Hoffmann, D.; Hurlimann, M. D.; Patz, S.; Schwartz, L. M.; Walsworth, R. L.

    1999-01-01

    We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of porous media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate rocks.

  16. Applications of 1H-NMR relaxometry in experimental liver studies

    International Nuclear Information System (INIS)

    Purpose of this study was to investigate applications of proton nuclear magnetic resonance (1H-NMR) relaxometry in experimental medicine. Relaxometry was performed by measurements of spin-lattice (T1) and spin-spin (T2) relaxation time parameters on liver biopsies up to four hours after biopsy excision. Variations of relaxation times due to species and strain, different sample handling and different liver damage models, ethionine fatty liver and paracetamol liver necrosis, were investigated. Cell integrity effects were studied on homogenized liver samples. Relaxation time parameters, especially 'main' components T1A and T2A of biexponential model fit, were identified to react very sensitive after tissue damages as well as to cell viability. Thus, investigation of stored liver grafts was performed in order to evaluate the possibility of a rapid liver graft viability testing method for human liver transplantation surgery by 1H-NMR relaxometry. Another series of measurements was performed to investigate the applicability of isoflurane anesthesia for in vivo NMR experiments. This study proved the good appropriateness of isoflurane for that purpose provided that physiological monitoring and individual adjustment of anesthesia are performed. In these investigations it could be revealed that mainly T1A and T2A are influenced by tissue condition and that different information is inherent id that different information is inherent in these two parameters, with T2A reflecting tissue viability and changes of tissue conditions very sensitively but rather unspecifically in respect to the damage applied. Based on these results the following future applications of 1H-NMR relaxometry are suggested : (1) model investigations, (2) investigation of given pathologies, (3) investigation of basic requirements for in vivo NMR and (4) application in a liver graft viability testing protocol, which seems to be the most important future application of 1H-NMR relaxometry in medicine. (author)

  17. The Corset Effect, Field-Cycling NMR Relaxometry, Transverse NMR Relaxation, Field-Gradient NMR Diffusometry, and Incoherent Neutron Scattering

    OpenAIRE

    Kimmich, Rainer; Fatkullin, Nail

    2010-01-01

    The corset effect is an experimentally established dynamic confinement phenomenon first observed by field-cycling NMR relaxometry and transverse NMR relaxation in polymer melts in pores with dimensions ranging from a few nanometers up to 0.06 micrometers or even more. The techniques employed are specifically sensitive to rotational fluctuations of polymer segments. It will be shown that neutron scattering and other methods probing translational fluctuations are not suitable ...

  18. ADAPT-NMR Enhancer: complete package for reduced dimensionality in protein NMR spectroscopy

    OpenAIRE

    Lee, Woonghee; Bahrami, Arash; Markley, John L.

    2012-01-01

    Summary: ADAPT-nuclear magnetic resonance (ADAPT-NMR) offers an automated approach to the concurrent acquisition and processing of protein NMR data with the goal of complete backbone and side chain assignments. What the approach lacks is a useful graphical interface for reviewing results and for searching for missing peaks that may have prevented assignments or led to incorrect assignments. Because most of the data ADAPT-NMR collects are 2D tilted planes used to find peaks in 3...

  19. NMR Analysis of Unknowns: An Introduction to 2D NMR Spectroscopy

    Science.gov (United States)

    Alonso, David E.; Warren, Steven E.

    2005-01-01

    A study combined 1D (one-dimensional) and 2D (two-dimensional) NMR spectroscopy to solve structural organic problems of three unknowns, which include 2-, 3-, and 4-heptanone. Results showed [to the first power]H NMR and [to the thirteenth power]C NMR signal assignments for 2- and 3-heptanone were more challenging than for 4-heptanone owing to the…

  20. 93Nb and 17O NMR chemical shifts of niobiophosphate compounds.

    Science.gov (United States)

    Flambard, A; Montagne, L; Delevoye, L; Steuernagel, S

    2007-10-01

    Niobiophosphate compounds with a large range of niobium and oxygen environments were studied with (93)Nb and (17)O solid-state NMR. (93)Nb isotropic chemical shift of pure niobate Nb(ONb)(6), pure phosphate Nb(OP)(6) and mixed phosphate-niobate Nb(OP)(x)(ONb)((6-x)) (1NMR spectra of a series of enriched samples provided the chemical shift and quadrupolar parameters for 4 types of oxygen environment (P-O-P, P-O-Na, P-O-Nb and Nb-O-Nb). Finally, Nb-O-Nb sites were characterized by a large (17)O chemical shift anisotropy. PMID:17728114

  1. Microscopic evidence of the FFLO state in CeCoIn5 probed by NMR study

    International Nuclear Information System (INIS)

    An anomalous temperature dependence of 115In-NMR spectrum is observed in the newly-discovered high field and low temperature superconducting phase of CeCoIn5. The anomalies near the upper limit of H C 2 are attributed to spatially-distributed local density of states of quasiparticles. From a simulation with the phenomenological model for the sinusoidally-modulated superconducting order parameter, the present NMR study provides a microscopic evidence that the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is realized at the high field phase in CeCoIn5. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. (35)Cl solid-state NMR of halide ionic liquids at ultrahigh fields.

    Science.gov (United States)

    Gordon, Peter G; Brouwer, Darren H; Ripmeester, John A

    2008-12-11

    This Letter describes recent work investigating the solid-state NMR spectra of (35)Cl nuclei in an assortment of ionic liquids under static and MAS conditions at field strengths of 9.4 and 21.1 T. At high field it was possible to resolve and extract information from multiple unique crystallographic sites and to resolve otherwise complex spectra that were analyzed to extract information regarding the electric field gradient (EFG) and chemical shift tensors, including their relative orientation. The NMR parameters were found to be typical of organic salts in general. PMID:19007195

  3. Grape juice quality control by means of ¹H nmr spectroscopy and chemometric analyses

    Scientific Electronic Library Online (English)

    Caroline Werner Pereira da Silva, Grandizoli; Francinete Ramos, Campos; Fabio, Simonelli; Andersson, Barison.

    1227-12-01

    Full Text Available This work shows the application of ¹H NMR spectroscopy and chemometrics for quality control of grape juice. A wide range of quality assurance parameters were assessed by single ¹H NMR experiments acquired directly from juice. The investigation revealed that conditions and time of storage should be r [...] evised and indicated on all labels. The sterilization process of homemade grape juices was efficient, making it possible to store them for long periods without additives. Furthermore, chemometric analysis classified the best commercial grape juices to be similar to homemade grape juices, indicating that this approach can be used to determine the authenticity after adulteration.

  4. 31P NMR knights shifts in the UPY (Y = S, Se, Te) compounds

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance of 31P measurements have been made for UPY (where Y = S, Se and Te) compounds. The resonance lines show the effect of anisotropic Knight shifts. In the UPS, the NMR data indicate an axial symmetry of the phosphorus environment whereas for UPSe and UPTe the symmetry is lower than the axial one. The result for UPSe disagrees with earlier structural studies. An analysis of NMR spectra indicates that both the asymmetry parameter epsilon and the isotropic component of the Knight shift increase with the increase of atomic weight of the Y element. (orig.)

  5. Validation of quantitative 1H NMR method for the analysis of pharmaceutical formulations

    International Nuclear Information System (INIS)

    The need for effective and reliable quality control in products from pharmaceutical industries renders the analyses of their active ingredients and constituents of great importance. This study presents the theoretical basis of ¹H NMR for quantitative analyses and an example of the method validation according to Resolution RE N. 899 by the Brazilian National Health Surveillance Agency (ANVISA), in which the compound paracetamol was the active ingredient. All evaluated parameters (selectivity, linearity, accuracy, repeatability and robustness) showed satisfactory results. It was concluded that a single NMR measurement provides structural and quantitative information of active components and excipients in the sample. (author)

  6. Substituent Effects in the 13C-NMR Spectra of Six-Membered Nitrogen Heteroaromatic Compounds

    Directory of Open Access Journals (Sweden)

    Janusz Oszczapowicz

    2005-01-01

    Full Text Available Abstract: It is shown that the 13C-NMR chemical shifts of carbon atoms in substituted sixmembered heteroaromatic compounds correlate with the correponding "additivity parameters" for substituted benzene derivatives. Thus, for precalculation of chemical shifts in such compounds, just one set of parameters can be used. The differences between experimental chemical shifts and those calculated from correlation with the common set may provide insights into intramolecular interactions not reported in the literature.

  7. Solid-state 13C NMR spectroscopic, chemolytic and biological assessment of pretreated municipal solid waste

    OpenAIRE

    Pichler, M.; Knicker, Heike; Kögel-Knabner, I.

    2001-01-01

    In Central Europe, composting and anaerobic digestion of municipal solid waste (MSW) is used as pretreatment before landfilling to reduce landfill emissions. MSW samples were analyzed before, during, and after pretreatment to assess the stability of the organic matter. Chemolytic, nuclear magnetic resonance (NMR) spectroscopic, and respiration parameters were correlated to evaluate a substitution of the time-consuming respiration analysis by chemical parameters. 13C cross polarization magic a...

  8. 33S NMR cryogenic probe for taurine detection

    Science.gov (United States)

    Hobo, Fumio; Takahashi, Masato; Maeda, Hideaki

    2009-03-01

    With the goal of a S33 nuclear magnetic resonance (NMR) probe applicable to in vivo NMR on taurine-biological samples, we have developed the S33 NMR cryogenic probe, which is applicable to taurine solutions. The NMR sensitivity gain relative to a conventional broadband probe is as large as 3.5. This work suggests that improvements in the preamplifier could allow NMR measurements on 100 ?M taurine solutions, which is the level of sensitivity necessary for biological samples.

  9. NMR data visualization, processing, and analysis on mobile devices.

    Science.gov (United States)

    Cobas, Carlos; Fernández, Isaac Iglesias; Otero, Felipe Seoane

    2015-08-01

    The design and technical development and capabilities of a new NMR app operating on both Android and iOS platforms to quickly visualize, process, analyze, and share NMR data on mobile devices, 'anywhere, anytime' are described. Routine 1D and 2D NMR spectra acquired in both high field and benchtop NMR instruments are fully supported. More advanced experiments such as non-uniform sampled NMR spectra can also be processed. PMID:26200331

  10. A new laboratory approach to shale analysis using NMR relaxometry

    Science.gov (United States)

    Washburn, Kathryn E.; Birdwell, Justin E.

    2013-01-01

    Low-field nuclear magnetic resonance (LF-NMR) relaxometry is a non-invasive technique commonly used to assess hydrogen-bearing fluids in petroleum reservoir rocks. Measurements made using LF-NMR provide information on rock porosity, pore-size distributions, and in some cases, fluid types and saturations (Timur, 1967; Kenyon et al., 1986; Straley et al., 1994; Brown, 2001; Jackson, 2001; Kleinberg, 2001; Hurlimann et al., 2002). Recent improvements in LF-NMR instrument electronics have made it possible to apply methods used to measure pore fluids to assess highly viscous and even solid organic phases within reservoir rocks. T1 and T2 relaxation responses behave very differently in solids and liquids; therefore the relationship between these two modes of relaxation can be used to differentiate organic phases in rock samples or to characterize extracted organic materials. Using T1-T2 correlation data, organic components present in shales, such as kerogen and bitumen, can be examined in laboratory relaxometry measurements. In addition, implementation of a solid-echo pulse sequence to refocus T2 relaxation caused by homonuclear dipolar coupling during correlation measurements allows for improved resolution of solid-phase protons. LF-NMR measurements of T1 and T2 relaxation time distributions were carried out on raw oil shale samples from the Eocene Green River Formation and pyrolyzed samples of these shales processed by hydrous pyrolysis and techniques meant to mimic surface and in-situ retorting. Samples processed using the In Situ Simulator approach ranged from bitumen and early oil generation through to depletion of petroleum generating potential. The standard T1-T2 correlation plots revealed distinct peaks representative of solid- and liquid-like organic phases; results on the pyrolyzed shales reflect changes that occurred during thermal processing. The solid-echo T1 and T2 measurements were used to improve assessment of the solid organic phases, specifically kerogen, thermally degraded kerogen, and char. Integrated peak areas from the LF-NMR results representative of kerogen and bitumen were found to be well correlated with S1 and S2 parameters from Rock-Eval programmed pyrolysis. This study demonstrates that LFNMR relaxometry can provide a wide range of information on shales and other reservoir rocks that goes well beyond porosity and pore-fluid analysis.

  11. Quantitative analysis of NMR spectra with chemometrics

    Science.gov (United States)

    Winning, H.; Larsen, F. H.; Bro, R.; Engelsen, S. B.

    2008-01-01

    The number of applications of chemometrics to series of NMR spectra is rapidly increasing due to an emerging interest for quantitative NMR spectroscopy e.g. in the pharmaceutical and food industries. This paper gives an analysis of advantages and limitations of applying the two most common chemometric procedures, Principal Component Analysis (PCA) and Multivariate Curve Resolution (MCR), to a designed set of 231 simple alcohol mixture (propanol, butanol and pentanol) 1H 400 MHz spectra. The study clearly demonstrates that the major advantage of chemometrics is the visualisation of larger data structures which adds a new exploratory dimension to NMR research. While robustness and powerful data visualisation and exploration are the main qualities of the PCA method, the study demonstrates that the bilinear MCR method is an even more powerful method for resolving pure component NMR spectra from mixtures when certain conditions are met.

  12. NMR studies of cerebral metabolism in vivo

    International Nuclear Information System (INIS)

    The nature and extent of the potential synergism between PET and NMR methods is not yet well appreciated in the biomedical community. The long-range interest of medical neurobiology will be well served by efforts of PET and NMR scientists to follow each others' work so that opportunities for productive interchange can be efficiently exploited. Appreciation of the synergism by the rest of the biomedical community will follow naturally. PET is said by the people doing it to be still in its infancy, for they are more concerned with advancing their discipline than with admiring its already impressive achievements. On the scale of the same developmental metaphor, many NMR methods for studying the living human brain are still in utero. The best way to provide the reader a sense of the current status and future course of NMR research in medical neurobiology is by discussion of published in vivo studies. Such a discussion, adapted from another article is what follows

  13. NMR and optical studies of piezoelectric polymers

    International Nuclear Information System (INIS)

    Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF2) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done

  14. Bayesian Peak Picking for NMR Spectra

    KAUST Repository

    Cheng, Yichen

    2014-02-01

    Protein structure determination is a very important topic in structural genomics, which helps people to understand varieties of biological functions such as protein-protein interactions, protein–DNA interactions and so on. Nowadays, nuclear magnetic resonance (NMR) has often been used to determine the three-dimensional structures of protein in vivo. This study aims to automate the peak picking step, the most important and tricky step in NMR structure determination. We propose to model the NMR spectrum by a mixture of bivariate Gaussian densities and use the stochastic approximation Monte Carlo algorithm as the computational tool to solve the problem. Under the Bayesian framework, the peak picking problem is casted as a variable selection problem. The proposed method can automatically distinguish true peaks from false ones without preprocessing the data. To the best of our knowledge, this is the first effort in the literature that tackles the peak picking problem for NMR spectrum data using Bayesian method.

  15. Epitope mapping by solution NMR spectroscopy.

    Science.gov (United States)

    Bardelli, M; Livoti, E; Simonelli, L; Pedotti, M; Moraes, A; Valente, A P; Varani, L

    2015-06-01

    Antibodies play an ever more prominent role in basic research as well as in the biotechnology and pharmaceutical sectors. Characterizing their epitopes, that is, the region that they recognize on their target molecule, is useful for purposes ranging from molecular biology research to vaccine design and intellectual property protection. Solution NMR spectroscopy is ideally suited to the atomic level characterization of intermolecular interfaces and, as a consequence, to epitope discovery. Here, we illustrate how NMR epitope mapping can be used to rapidly and accurately determine protein antigen epitopes. The basic concept is that differences in the NMR signal of an antigen free or bound by an antibody will identify epitope residues. NMR epitope mapping provides more detailed information than mutagenesis or peptide mapping and can be much more rapid than X-ray crystallography. Advantages and drawbacks of this technique are discussed together with practical considerations. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25726811

  16. Theoretical NMR correlations based Structure Discussion

    OpenAIRE

    Junker Jochen

    2011-01-01

    Abstract The constitutional assignment of natural products by NMR spectroscopy is usually based on 2D NMR experiments like COSY, HSQC, and HMBC. The actual difficulty of the structure elucidation problem depends more on the type of the investigated molecule than on its size. The moment HMBC data is involved in the process or a large number of heteroatoms is present, a possibility of multiple solutions fitting the same data set exists. A structure elucidation software can be used to find such ...

  17. Scalable NMR Spectroscopy with Semiconductor Chips

    OpenAIRE

    Ha, Dongwan

    2014-01-01

    Conventional nuclear magnetic resonance (NMR) spectrometers—the electronic brain that orchestrates and monitors nuclear spin motions—are bulky, expensive, thus, not scalable. In this thesis, we report on scalable 4-mm2 silicon spectrometer chips that perform a broad range of two-dimensional NMR spectroscopy—e.g., correlation spectroscopy, J-resolved spectroscopy, and heteronuclear quantum coherence spectroscopy—as well as one-dimensional spectroscopy and relaxometry. I...

  18. Annual Reports on NMR Spectroscopy. Volume 58

    OpenAIRE

    Fagan, Andrew John

    2005-01-01

    A novel NMR technique for imaging materials exhibiting extremely short T2 relaxation times is described and some examples of its application to materials of scientific and industrial interest are presented. The technique employs continuous wave (CW) radiofrequency irradiation of the sample together with continual detection, and thus the experimental deadtime inherent in pulsed techniques is effectively eliminated. The mechanisms which broaden the NMR linewidths of materials in the solid state...

  19. Recent advances in SQUID NMR techniques

    International Nuclear Information System (INIS)

    A discussion of the techniques used for performing a variety of magnetic resonance experiments using a SQUID is presented. In particular, measurements of the nuclear magnetism of liquid 3He in the temperature range 1.2 K to 2 mK in magnetic fields of 3.7 to 309 Oe using pulsed NMR, c-w NMR, adiabatic fast passage, and static susceptibility using the same detection system are discussed

  20. Frontiers of NMR in Molecular Biology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-08-25

    NMR spectroscopy is expanding the horizons of structural biology by determining the structures and describing the dynamics of blobular proteins in aqueous solution, as well as other classes of proteins including membrane proteins and the polypeptides that form the aggregates diagnostic of prion and amyloid diseases. Significant results are also emerging on DNA and RNA oligomers and their complexes with proteins. This meeting focused attention on key structural questions emanating from molecular biology and how NMR spectroscopy can be used to answer them.

  1. Multinuclear NMR characterization of microemulsions

    International Nuclear Information System (INIS)

    One major goal of heterogeneous catalysis by metals is the preparation of small and uniform particles. This can be achieved partially by depositing them on a support, which in turn decreases their ability for sintering. Nevertheless, these particles show, in most cases, a rather broad distribution in size and/or a bimodal distribution. A new method is proposed for the preparation of very small (20-70 A) monodisperse particles of Ni2B, Co2B and Ni-Co-B, and their formation is examined from a mechanistic point of view. These catalysts are used in room-temperature liquid-phase hydrogenation and they are synthesized by reduction with NaBH4 of Ni(II) and Co(II) ionns solubilized in one of the microemulsions composed of cetyltrimethylammonium bromide (CTAB), hexan-1-ol and water. The solubilization sites and the interaction of Co(II) and Ni(II) ions with CTAB or hexan-1-ol molecules were studied by 13C-NMR and by UV-VIS absorption spectroscopy. It is concluded that the metallic ions are basically solvated in the inner water cores and one or more hexan-1-ol molecules are included in their first solvation shells. The size of the inner water core is measured by an indirect method (19F-NMR), based on the distribution of 6-fluorohexan-1-ol between the interface and the hexan-1-ol organic medium. The size of metal boride particles depends upon the micellar composition (especially on the water concentration) and on the metal ihe water concentration) and on the metal ion concentration. Larger particles are obtained at higher water content, while the curve of particle size as a function of Co(II) or Ni(II) concentration showed a clear-cut minimum. This latter can be explained, provided a critical number of Co(II) or Ni(II) ions is assumed for the formation of nuclei. (author). 40 refs.; 6 figs.; 2 tabs

  2. Solid-state NMR in the analysis of drugs and naturally occurring materials.

    Science.gov (United States)

    Paradowska, Katarzyna; Wawer, Iwona

    2014-05-01

    This article presents some of the solid-state NMR (SSNMR) techniques used in the pharmaceutical and biomedical research. Solid-state magic angle spinning (MAS) NMR provides structural information on powder amorphous solids for which single-crystal diffraction structures cannot be obtained. NMR is non-destructive; the powder sample may be used for further studies. Quantitative results can be obtained, although solid-state NMR spectra are not normally quantitative. As compared with other techniques, MAS NMR is insensitive and requires a significant amount of the powder sample (2-100mg) to fill the 1.3-7 mm ZrO2 rotor. This is its main drawback, since natural compounds isolated from plants, microorganisms or cell cultures are difficult to obtain in quantities higher than a few milligrams. Multinuclear MAS NMR routinely uses (1)H and (13)C nuclei, less frequently (15)N, (19)F, (31)P, (77)Se, (29)Si, (43)Ca or (23)Na. The article focuses on the pharmaceutical applications of SSNMR, the studies were aimed to control over manufacturing processes (e.g. crystallization and milling) investigation of chemical and physical stability of solid forms both as pure drug and in a formulated product. SSNMR is used in combination with some other analytical methods (DSC, XRD, FT-IR) and theoretical calculations of NMR parameters. Biologically active compounds, such as amino acids and small peptides, steroids and flavonoids were studied by SSNMR methods (part 4) providing valuable structural information. The SSNMR experiments performed on biopolymers and large natural products like proteins, cellulose and lipid layers are commented upon briefly in part 5. PMID:24173236

  3. Quantitative Analysis of STD-NMR Spectra of Reversibly Forming Ligand-Receptor Complexes

    Science.gov (United States)

    Krishna, N. Rama; Jayalakshmi, V.

    We describe our work on the quantitative analysis of STD-NMR spectra of reversibly forming ligand-receptor complexes. This analysis is based on the theory of complete relaxation and conformational exchange matrix analysis of saturation transfer (CORCEMA-ST) effects. As part of this work, we have developed two separate versions of the CORCEMA-ST program. The first version predicts the expected STD intensities for a given model of a ligand-protein complex, and compares them quantitatively with the experimental data. This version is very useful for rapidly determining if a model for a given ligand-protein complex is compatible with the STD-NMR data obtained in solution. It is also useful in determining the optimal experimental conditions for undertaking the STD-NMR measurements on a given complex by computer simulations. In the second version of the CORCEMA-ST program, we have implemented a torsion angle refinement feature for the bound ligand within the protein binding pocket. In this approach, the global minimum for the bound ligand conformation is obtained by a hybrid structure refinement protocol involving CORCEMA-ST calculation of intensities and simulated annealing refinement of torsion angles of the bound ligand using STD-NMR intensities as experimental constraints to minimize a pseudo-energy function. This procedure is useful in refining and improving the initial models based on crystallography, computer docking, or other procedures to generate models for the bound ligand within the protein binding pocket compatible with solution STD-NMR data. In this chapter we describe the properties of the STD-NMR spectra, including the dependence of the intensities on various parameters. We also describe the results of the CORCEMA-ST analyses of experimental STD-NMR data on some ligand-protein complexes to illustrate the quantitative analysis of the data using this method. This CORCEMA-ST program is likely to be useful in structure-based drug design efforts.

  4. A microscale protein NMR sample screening pipeline

    International Nuclear Information System (INIS)

    As part of efforts to develop improved methods for NMR protein sample preparation and structure determination, the Northeast Structural Genomics Consortium (NESG) has implemented an NMR screening pipeline for protein target selection, construct optimization, and buffer optimization, incorporating efficient microscale NMR screening of proteins using a micro-cryoprobe. The process is feasible because the newest generation probe requires only small amounts of protein, typically 30-200 ?g in 8-35 ?l volume. Extensive automation has been made possible by the combination of database tools, mechanization of key process steps, and the use of a micro-cryoprobe that gives excellent data while requiring little optimization and manual setup. In this perspective, we describe the overall process used by the NESG for screening NMR samples as part of a sample optimization process, assessing optimal construct design and solution conditions, as well as for determining protein rotational correlation times in order to assess protein oligomerization states. Database infrastructure has been developed to allow for flexible implementation of new screening protocols and harvesting of the resulting output. The NESG micro NMR screening pipeline has also been used for detergent screening of membrane proteins. Descriptions of the individual steps in the NESG NMR sample design, production, and screening pipeline are presented in the format of a standard operating procedure.erating procedure.

  5. Parameter Estimation

    DEFF Research Database (Denmark)

    Sales-Cruz, Mauricio; Heitzig, Martina

    2011-01-01

    In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models.

  6. NMR-Based Multi Parametric Quality Control of Fruit Juices: SGF Profiling

    Directory of Open Access Journals (Sweden)

    Fang Fang

    2009-11-01

    Full Text Available With SGF Profiling™ we introduce an NMR-based screening method for the quality control of fruit juices. This method has been developed in a joint effort by Bruker BioSpin GmbH and SGF International e.V. The system is fully automated with respect to sample transfer, measurement, data analysis and reporting and is set up on an Avance 400 MHz flow-injection NMR spectrometer. For each fruit juice a multitude of parameters related to quality and authenticity are evaluated simultaneously from a single data set acquired within a few minutes. This multimarker/multi-aspect NMR screening approach features low cost-per-sample and is highly competitive with conventional and targeted fruit juice quality control methods.

  7. 63,65Cu NMR Method in a Local Field for Investigation of Copper Ore Concentrates

    Science.gov (United States)

    Gavrilenko, A. N.; Starykh, R. V.; Khabibullin, I. Kh.; Matukhin, V. L.

    2015-01-01

    To choose the most efficient method and ore beneficiation flow diagram, it is important to know physical and chemical properties of ore concentrates. The feasibility of application of the 63,65Cu nuclear magnetic resonance (NMR) method in a local field aimed at studying the properties of copper ore concentrates in the copper-iron-sulfur system is demonstrated. 63,65Cu NMR spectrum is measured in a local field for a copper concentrate sample and relaxation parameters (times T1 and T2) are obtained. The spectrum obtained was used to identify a mineral (chalcopyrite) contained in the concentrate. Based on the experimental data, comparative characteristics of natural chalcopyrite and beneficiated copper concentrate are given. The feasibility of application of the NMR method in a local field to explore mineral deposits is analyzed.

  8. Residual broadening in high-resolution NMR of quadrupolar nuclei in solids

    CERN Document Server

    McManus, J

    2001-01-01

    amorphous materials. The spectra of these compounds show significant additional broadening due to the presence of distributions of chemical shift and quadrupolar parameters. A lineshape-fitting routine is proposed, tested and applied to obtain quantitative estimates of these distributions in the sup 2 sup 7 AI MQMAS NMR spectra of a series of amorphous aluminosilicate compounds. Solid-state NMR spectra of quadrupolar nuclei are often poorly resolved due to the presence of anisotropic second-order quadrupolar broadening, even under conventional magic angle spinning (MAS) conditions. The two-dimensional multiple-quantum MAS (MQMAS) experiment is one of several techniques which have been designed to remove this broadening and provide high-resolution NMR spectra of half-integer quadrupolar nuclei. This thesis demonstrates that, in the absence of this pure quadrupolar broadening, it is possible to observe a weak quadrupolar-dipolar interaction which also survives conventional MAS and is the result of dipolar coupl...

  9. A simulated annealing approach for solving zeolite crystal structures from two-dimensional NMR correlation spectra.

    Science.gov (United States)

    Brouwer, Darren H; Horvath, Matthew

    2015-02-01

    An improved NMR crystallography strategy is presented for determining the structures of network materials such as zeolites from just a single two-dimensional (2D) NMR correlation spectrum that probes nearest-neighbor interactions, combined with the unit cell parameters and space group information measured in a diffraction experiment. The correlation information contained within a 2D spectrum is converted into a "connectivity matrix" which is incorporated into a cost function whose minimum is searched for using a simulated annealing algorithm. The algorithm was extensively tested on over 150 zeolite frameworks from the International Zeolite Association database of zeolite structures and shown to be very robust and efficient in reconstructing the structures from connectivity information. The structure determination of the pure silica zeolites ITQ-4, Ferrierite, and Sigma-2 from experimental 2D (29)Si double-quantum NMR spectra and powder X-ray diffraction data using this improved approach is also presented. PMID:25466355

  10. Optically detected NMR of optically hyperpolarized 31P neutral donors in 28Si

    CERN Document Server

    Steger, M; Yang, A; Saeedi, K; Hayden, M E; Thewalt, M L W; Itoh, K M; Riemann, H; Abrosimov, N V; Becker, P; Pohl, H -J

    2010-01-01

    The electron and nuclear spins of the shallow donor 31P are promising qubit candidates invoked in many proposed Si-based quantum computing schemes. We have recently shown that the near-elimination of inhomogeneous broadening in highly isotopically enriched 28Si enables an optical readout of both the donor electron and nuclear spins by resolving the donor hyperfine splitting in the near-gap donor bound exciton transitions. We have also shown that pumping these same transitions can very quickly produce large electron and nuclear hyperpolarizations at low magnetic fields, where the equilibrium electron and nuclear polarizations are near zero. Here we show preliminary results of the measurement of 31P neutral donor NMR parameters using this optical nuclear hyperpolarization mechanism for preparation of the 31P nuclear spin system, followed by optical readout of the resulting nuclear spin population after manipulation with NMR pulse sequences. This allows for the observation of single-shot NMR signals with very hi...

  11. A new de-noising method of NMR FID signals based on wavelet transform

    International Nuclear Information System (INIS)

    Taking aim at the de-noising of clinical NMR FID signals, the paper analyzes the wavelet transform characteristic of available signals and noises separately based on wavelet transform technology. With the principles of three de-noising methods wavelet-based, wavelet transform modulus maxima, threshold shrinkage, and translation invariance. Effective solutions for selecting method of wavelet basis function, optimized thresholding function and wavelet decomposing parameters are put forward, so as the distinguishing method between signals and noises. Taking brain gliomas as an example, the paper implements effective experimental solutions based on the wavelet transform de-noising technology. About 30 clinical NMR data obtained from the NMR devices have been de-noised to provide high quality data and validated the new method. (authors)

  12. NMR structural study of the prototropic equilibrium in solution of Schiff bases as model compounds.

    Science.gov (United States)

    Ortegón-Reyna, David; Garcías-Morales, Cesar; Padilla-Martínez, Itzia; García-Báez, Efren; Aríza-Castolo, Armando; Peraza-Campos, Ana; Martínez-Martínez, Francisco

    2013-01-01

    An NMR titration method has been used to simultaneously measure the acid dissociation constant (pKa) and the intramolecular NHO prototropic constant ?KNHO on a set of Schiff bases. The model compounds were synthesized from benzylamine and substituted ortho-hydroxyaldehydes, appropriately substituted with electron-donating and electron-withdrawing groups to modulate the acidity of the intramolecular NHO hydrogen bond. The structure in solution was established by 1H-, 13C- and 15N-NMR spectroscopy. The physicochemical parameters of the intramolecular NHO hydrogen bond (pKa, ?KNHO and ??G°) were obtained from 1H-NMR titration data and pH measurements. The Henderson-Hasselbalch data analysis indicated that the systems are weakly acidic, and the predominant NHO equilibrium was established using Polster-Lachmann ?-diagram analysis and Perrin model data linearization. PMID:24384925

  13. Identifying Stereoisomers by ab-initio Calculation of Secondary Isotope Shifts on NMR Chemical Shieldings

    Directory of Open Access Journals (Sweden)

    Karl-Heinz Böhm

    2014-04-01

    Full Text Available We present ab-initio calculations of secondary isotope effects on NMR chemical shieldings. The change of the NMR chemical shift of a certain nucleus that is observed if another nucleus is replaced by a different isotope can be calculated by computing vibrational corrections on the NMR parameters using electronic structure methods. We demonstrate that the accuracy of the computational results is sufficient to even distinguish different conformers. For this purpose, benchmark calculations for fluoro(2-2Hethane in gauche and antiperiplanar conformation are carried out at the HF, MP2 and CCSD(T level of theory using basis sets ranging from double- to quadruple-zeta quality. The methodology is applied to the secondary isotope shifts for 2-fluoronorbornane in order to resolve an ambiguity in the literature on the assignment of endo- and exo-2-fluoronorbornanes with deuterium substituents in endo-3 and exo-3 positions, also yielding insight into mechanistic details of the corresponding synthesis.

  14. Early non-destructive biofouling detection in spiral wound RO Membranes using a mobile earth's field NMR

    KAUST Repository

    Fridjonsson, E.O.

    2015-04-20

    We demonstrate the use of Earth\\'s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (signal relaxation parameters T1, T2 and the total NMR signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  15. NMR study of hydride systems

    International Nuclear Information System (INIS)

    The hydrides of thorium (ThH2, Th4H15 and Th4D15) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x))2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th4H15 than in ThH2; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th4H15; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

  16. NMR in highly correlated superconductors

    International Nuclear Information System (INIS)

    Results of our systematic NMR study in high Tc cuprates are reviewed. The antiferromagnetic spin fluctuations (AFSF) decrease in the order of La1.85Sr0.15CuO4. YBa2Cu3O7 and Tl2Ba2CuO6+y. 1/T1 of 63Cu in the CuO2 plane in the normal state follows essentially a Curie-Weiss law at high temperature and T1T = const. law at low temperature. The temperature dependence of 1/T1 and the Knight shift together with their impurity effect in the superconducting state strongly suggest d-wave pairing implying the AFSF to be responsible for the occurrence of superconductivity. From the NQR frequency measurement the density of Cu 3d and O 2p holes decreases and increases, respectively, in the order of La, Y and Tl compounds, which is consistent with the change of AFSF. The relation between Tc and ?Q, and their pressure dependence suggest that there exists and optimum value of the ratio of Cu 3d and O 2p hole density to give a maximum in Tc. (orig.)

  17. Solid-state 27Al MRI and NMR thermometry for catalytic applications with conventional (liquids) MRI instrumentation and techniques.

    Science.gov (United States)

    Koptyug, Igor V; Sagdeev, Dmitry R; Gerkema, Edo; Van As, Henk; Sagdeev, Renad Z

    2005-07-01

    Multidimensional images of Al2O3 pellets, cordierite monolith, glass tube, polycrystalline V2O5 and other materials have been detected by 27Al, 51V, and 23Na NMR imaging using techniques and instrumentation conventionally employed for imaging of liquids. These results demonstrate that, contrary to the widely accepted opinion, imaging of "rigid" solids does not necessarily require utilization of solid state NMR imaging approaches, pulse sequences and hardware even for quadrupolar nuclei which exhibit line widths in excess of 100 kHz, such as 51V in polycrystalline V2O5. It is further demonstrated that both 27Al NMR signal intensity and spin-lattice relaxation time decrease with increasing temperature and thus can potentially serve as temperature sensitive parameters for spatially resolved NMR thermometry. PMID:15949745

  18. Determination of relative natural isotopic abundance of 2H using NMR spectroscopy and application in food analysis

    International Nuclear Information System (INIS)

    The basic relations are defined for determining the content of deuterium in compound CXHP. Hydrogen atoms 1H and 2H are distributed among the individual diastereotopic points in the molecule which is either monodeuterized or non deuterized. The SNIF-NMR parameter is derived from these assumptions. Procedures are presented for preparing samples for NMR experiments. For measuring NMR spectra of 2H the effects are considered of relaxation times and the total time of measurement. Relaxation times of deuterium in small molecules are of the order of 1 second. The possibilities are shown of using 2H NMR spectroscopy for the study of deuterium transfer during chemical and biochemical reactions, for the determination of isotope purity, the determination of the origin of the sample and for the surveillance of technological processes. Examples of the applications are given. (E.S.). 3 figs., 8 tabs., 42 refs

  19. Wine analysis to check quality and authenticity by fully-automated 1H-NMR

    Directory of Open Access Journals (Sweden)

    Spraul Manfred

    2015-01-01

    Full Text Available Fully-automated high resolution 1H-NMR spectroscopy offers unique screening capabilities for food quality and safety by combining non-targeted and targeted screening in one analysis (15–20?min from acquisition to report. The advantage of high resolution 1H-NMR is its absolute reproducibility and transferability from laboratory to laboratory, which is not equaled by any other method currently used in food analysis. NMR reproducibility allows statistical investigations e.g. for detection of variety, geographical origin and adulterations, where smallest changes of many ingredients at the same time must be recorded. Reproducibility and transferability of the solutions shown are user-, instrument- and laboratory-independent. Sample prepara- tion, measurement and processing are based on strict standard operation procedures which are substantial for this fully automated solution. The non-targeted approach to the data allows detecting even unknown deviations, if they are visible in the 1H-NMR spectra of e.g. fruit juice, wine or honey. The same data acquired in high-throughput mode are also subjected to quantification of multiple compounds. This 1H-NMR methodology will shortly be introduced, then results on wine will be presented and the advantages of the solutions shown. The method has been proven on juice, honey and wine, where so far unknown frauds could be detected, while at the same time generating targeted parameters are obtained.

  20. Quantitation of lung water by NMR imaging: A preliminary study

    International Nuclear Information System (INIS)

    This study investigates the relation of the NMR spin-lattice relaxation time (T/sub 1/) to tissue wetness in an animal model of pulmonary edema. Imaging was performed with a whole-body resistive magnet prototype NMR imager (Technicare, Inc.) operating at 0.15T. Following control NMR imaging, mongrel, mongrel dogs (n=4) were anesthetized and subjected to saline pulmonary lavage (15 ml/kg) while in a lateral position, repeated 2-5 times to produce mild to severe edema and hypoxemia (prelavage, on 100%, P/sub a/O/sub 2/ > 300 mm Hg; post lavage P/sub a/O/sub 2/ 65-85 mm Hg). The animals were maintained on positive pressure ventilation with halothane/O/sub 2/. Model P/sub a/O/sub 2/ stability was 15%/hr. Axial NMR images were obtained at the level of the carina. Partial saturation pulse sequences (900-1800-spin echo) were used in which the T/sub 2/ parameter was held constant (time to echo, T/sub E/) at 30 msec, while the T/sub 1/ parameter (repetition rate, T/sub R/) varied in multiple steps from 500-4500 msec, allowing production of a parametric image of T/sub 1/ distribution. Following sacrifice, two 1-cm thick transverse sections were removed from the lungs at the level of the carina. One set of transverse sections was analyzed intact and from the adjacent section four samples (approx. 5 cm/sup 2/) were excised. Gravimetric measurement of dry and wet weight was done, and comparison made to T/sub 1/ measurements found by in vivo imaging. Tissue weements found by in vivo imaging. Tissue wetness bore a linear relation to T/sub 1/ both when lung samples (n=12, r=0.7, rho<0.02) and whole slices (n=8, r=0.66, rho? 0.05) were used. The data also corresponds well to previous data determined in vitro at a different field strength, using a different animal model. Thus, T/sub 1/ calculation may allow quantitation of lung water

  1. Investigation of ferroelectric nanostructured systems by ESR and NMR methods

    International Nuclear Information System (INIS)

    Full text: The theoretical and experimental investigation of ferroelectric nanopowders is performed. Since the most prominent size effect in ferroelectric nanomaterials was known to be size driven ferroelectric-paraelectric phase transition at some critical particle size R = Rcr the study of this effect manifestation in radiospectroscopy spectra was the main goal of the paper. In the theoretical part, the size effect of the parameters of the central transition +1/2 -1/2 lines which are known to be the most intensive for powder sample both in ESR and NMR are considered for the materials with ferroelectric tetragonal phase at room temperature and cubic paraelectric phase in the bulk. Therefore the transformation of axial symmetry spectra into cubic symmetry ones can be expected at R ? Rcr. For this transformation description the spontaneous polarization inhomogeneity inside a particle and distribution of particle sizes calculated previously were taken into account. Both these factors lead to inhomogeneous broadening of the lines. In ESR spectra the transformation of the spectra from axial symmetry to cubic symmetry lines was obtained with decreasing of nanoparticle sizes with practically complete disappearance of axial spectra at R ? Rcr. The method of Rcr value extraction from the ratio of the different symmetry spectra intensities was proposed. Size effect in NMR spectra for nuclei with quadrupole moments was consideei with quadrupole moments was considered, i.e. +1/2 -1/2 transition perturbed by second order quadrupole interaction of the nuclei with electric field gradient was calculated. Allowing for the absence of cubic symmetry in the vicinity of surface even in paraelectric phase, namely at R ? Rcr (P = 0), we described this size effect in core and shell model. Measurements of Fe3+ ESR spectra and 137Ba NMR spectra in nanopowder of BaTiO3 were carried out. The samples were prepared by rate-controlled method. Laser granulometry method analysis had shown that the particles sizes are distributed around two maxima with R bar ? 160 nm and R bar ? 40 nm. The decrease of intensity of axial symmetry ESR lines of Fe3+ and appearance of cubic symmetry line was observed with the average sizes decrease with complete disappearance of axial spectra at R bar ? 40 nm. NMR spectra practically did not change in all the samples although the essential narrowing of the line was expected at R ? Rcr. The comparison of the theory with experiment was carried out. The theory fits experimental data pretty good. The value of critical size Rcr ? 40 nm was extracted from ESR data. The asymmetry and broadening of right hand side shoulder of ESR cubic symmetry line was shown to be related to contribution of paramagnetic centers in the vicinity of the particles surface with lower than cubic symmetry. Such type of contribution to NMR line can be the main reason of absence of the pronounced size effect, namely the narrowing of the line, in NMR spectra of nuclei with quadrupole mechanism that defined the spectra main characteristics. The nuclei with chemical shift mechanism can be more sensitive for size effect investigations by NMR method. (author)

  2. Use of NMR and NMR Prediction Software to Identify Components in Red Bull Energy Drinks

    Science.gov (United States)

    Simpson, Andre J.; Shirzadi, Azadeh; Burrow, Timothy E.; Dicks, Andrew P.; Lefebvre, Brent; Corrin, Tricia

    2009-01-01

    A laboratory experiment designed as part of an upper-level undergraduate analytical chemistry course is described. Students investigate two popular soft drinks (Red Bull Energy Drink and sugar-free Red Bull Energy Drink) by NMR spectroscopy. With assistance of modern NMR prediction software they identify and quantify major components in each…

  3. Parameter libraries

    International Nuclear Information System (INIS)

    Full text: Recommendations for future parameter libraries: 1. The existing parameter library should be updated, extended and corrected regularly based on the latest measurements, evaluations and theoretical studies by international collaborations (through CRPs or other activities). What parts of the parameter library to be updated and corrected should be taken into account in setting up the activity. 2. New parameters should be added according to the new mechanisms or approaches introduced in the nuclear reaction model code and the updated results from nuclear theory studies. 3. Information on the range of parameters, especially for nuclear reaction model parameters used for covariance evaluations and sensitivity studies of nuclear data should be recommended. The information which can be used for this purpose should be considered based on the nuclear reaction models such like OM, DWBA, H-F and exciton model, etc. which are popular in the nuclear reaction model codes. 4. The model parameters (global and local) and related information for the unstable nuclei model calculations should be recommended and the uncertainties from the parameters for the model calculations of unstable nuclei should be studied and analyzed. 5. If some parameter systematics could be provided, it would help the nuclear data evaluators and nuclear data users to perform the model calculations. 6. CRPs and collaborations should be considered to address the above items. (author)bove items. (author)

  4. Research on physical properties using optical pump NMR: NMR of C-60FET and nanotubes

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) is recognized as a very powerful instrument for study of microstructure and electronic states, but the essential weak point is in its poor sensitivity. In order to overcome this weak point and to able to apply NMR to nanometer size region, a light irradiation method was introduced. In light pumping NMR, NMR is measured during irradiation of circularly polarized light being equivalent to transition energies of an electron system. The light pumping NMR instrument was set up, and experiments were tentatively carried out to silicon and GaAs wafers. Remarkable enhancement of signal intensity was observed in the experiment, but the mechanism of the enhancement was not fully resolved. (Y. Kazumata)

  5. Application of site-specific natural isotope fractionation (SNIF-NMR) of hydrogen to the characterization of European beers

    International Nuclear Information System (INIS)

    More than one hundred samples of European beers have been investigated by the new SNIF-NMR method which is based on 2H NMR at the natural abundance level and enables site-specific natural isotope fractionation factors in ethanol to be determined. The relative (R) and absolute (D/H)sub(i) parameters are shown to be characteristic of the country where the beers are brewed and the observed variations are explained in terms of cereal composition, water resource, and manufacturing processing (fermentation, yeast, temperature cycle). These new parameters find analytical and mechanistic applications in the identification of a beer and in the investigation of a fermentation process. (author)

  6. Measuring the contrast-enhancement in the skin and subcutaneous fatty tissue with the NMR-Mouse registered: a feasibility study

    International Nuclear Information System (INIS)

    Purpose: the NMR-Mouse registered is an open and mobile sensor for measuring NMR relaxation parameters in organic matters. T1-measurements of the subcutaneous fatty tissue and the skin are reported. Material and method: for the first time, the NMR-Mouse registered was employed to measure the signal recovery following saturation of the skin and the subcutaneous fatty tissue of three patients, before and after administering a contrast agent. Results: despite a low signal-to-noise ratio, changes in the relaxation behaviour of the skin could be detected. Malignant tissue exhibits faster signal recovery than scar tissue and healthy tissue, which only show a small difference. Conclusions: changes in the relaxation behavior can be monitored with the NMR-Mouse registered. Before the clinical use of the NMR-Mouse, sensitivity, sensor mounting device, and sensor tuning must be improved. Further investigations need to be performed on a statistically relevant number of patients. (orig.)

  7. Stacked planar micro coils for single-sided NMR applications

    Science.gov (United States)

    Watzlaw, Jan; Glöggler, Stefan; Blümich, Bernhard; Mokwa, Wilfried; Schnakenberg, Uwe

    2013-05-01

    This paper describes planar micro structured coils fabricated in a novel multilayer assembly for single-sided NMR experiments. By arranging the coil's turns in both lateral and vertical directions, all relevant coil parameters can be tailored to a specific application. To this end, we implemented an optimization algorithm based on simulations applying finite element methods (FEMs), which maximizes the coil's sensitivity and thus signal-to-noise ratio (SNR) while incorporating boundary conditions such as the coil's electrical properties and a localized sensitivity needed for single-sided applications. Utilizing thin-film technology and microstructuring techniques, the planar character is kept by a sub-millimeter overall thickness. The coils are adapted to the Profile NMR-MOUSE® magnet with a homogeneous slice of about 200 ?m in height and a uniform depth gradient of about 20 T/m. The final design of a coil with 20 turns, separated in four layers with five turns each, and an outer dimension of 4 × 4 mm2 is able to measure a sample volume almost five times smaller than that of a state-of-the-art 14 × 16 mm2 Profile NMR-MOUSE® coil with the same SNR. This allows for volume-limited measurements with high SNR and enables different future developments. The minimal dead time of 4 ?s facilitates further improvements of the SNR by echo adding techniques and the characterization of samples with short T2 relaxation times. Measurements on solid polymers like polyethylene (PE) and polypropylene (PP) with T2 components as short as 200 ?s approve the overall beneficial coil properties. Furthermore the ability to perform depth profiling with microscopic resolution is demonstrated.

  8. Variable-temperature NMR and conformational analysis of oenothein B

    Scientific Electronic Library Online (English)

    Suzana C., Santos; Ariadne G., Carvalho; Gilmara A. C., Fortes; Pedro H., Ferri; Anselmo E. de, Oliveira.

    2014-02-01

    Full Text Available Oenoteína B é um tanino hidrolisável dimérico com um amplo espectro de atividades biológicas, tais como antitumoral, anti-inflamatória e anti-viral. Seus espectros de ressonância magnética nuclear (RMN) à temperatura ambiente apresentam duplicações e alargamento de sinais. Experimentos de RMN uni e [...] bidimensionais a baixas temperaturas foram úteis no assinalamento de todos os sinais de hidrogênios e carbonos sem a necessidade de derivatização. A estrutura tridimensional do confôrmero mais estável foi determinada pela primeira vez através do experimento de espectroscopia de efeito nuclear Overhauser (NOESY) (-20 ºC) e cálculos computacionais usando métodos de teoria do funcional de densidade (DFT) (B3LYP/6-31G) e modelo contínuo polarizado (PCM). A conformação mais favorecida apresentou uma geometria altamente compactada e sem simetria, onde os dois grupos valoneoila mostraram diferentes parâmetros conformacionais e estabilidades. Abstract in english Oenothein B is a dimeric hydrolysable tannin with a wide range of biological activities, such as antitumour, anti-inflammatory and antiviral. Its nuclear magnetic resonance (NMR) at room temperature show duplications and broadening of signals. Experiments of 1D and 2D NMR at lower temperatures were [...] useful for the complete NMR assignments of all hydrogens and carbons. The 3D structure of the most stable conformer was determined for the first time by nuclear Overhauser effect spectroscopy (NOESY) experiment (-20 ºC) and density functional theory (DFT)(B3LYP/6-31G)/ polarizable continuum model (PCM) quantum chemical calculations. The favoured conformation showed a highly compacted geometry and a lack of symmetry, in which the two valoneoyl groups showed distinct conformational parameters and stabilities.

  9. BOOK REVIEW: NMR Imaging of Materials

    Science.gov (United States)

    Blümich, Bernhard

    2003-09-01

    Magnetic resonance imaging (MRI) of materials is a field of increasing importance. Applications extend from fundamental science like the characterization of fluid transport in porous rock, catalyst pellets and hemodialysers into various fields of engineering for process optimization and product quality control. While the results of MRI imaging are being appreciated by a growing community, the methods of imaging are far more diverse for materials applications than for medical imaging of human beings. Blümich has delivered the first book in this field. It was published in hardback three years ago and is now offered as a paperback for nearly half the price. The text provides an introduction to MRI imaging of materials covering solid-state NMR spectroscopy, imaging methods for liquid and solid samples, and unusual MRI in terms of specialized approaches to spatial resolution such as an MRI surface scanner. The book represents an excellent and thorough treatment which will help to grow research in materials MRI. Blümich developed the treatise over many years for his research students, graduates in chemistry, physics and engineering. But it may also be useful for medical students looking for a less formal discussion of solid-state NMR spectroscopy. The structure of this book is easy to perceive. The first three chapters cover an introduction, the fundamentals and methods of solid-state NMR spectroscopy. The book starts at the ground level where no previous knowledge about NMR is assumed. Chapter 4 discusses a wide variety of transformations beyond the Fourier transformation. In particular, the Hadamard transformation and the 'wavelet' transformation are missing from most related books. This chapter also includes a description of noise-correlation spectroscopy, which promises the imaging of large objects without the need for extremely powerful radio-frequency transmitters. Chapters 5 and 6 cover basic imaging methods. The following chapter about the use of relaxation and spectroscopic methods to weight or filter the spin signals represents the core of the book. This is a subject where Blümich is deeply involved with substantial contributions. The chapter includes a lot of ideas to provide MR contrast between different regions based on their mobility, diffusion, spin couplings or NMR spectra. After describing NMR imaging methods for solids with broad lines, Blümich spends time on applications in the last two chapters of the book. This part is really fun to read. It underlines the effort to bring NMR into many kinds of manufacturing. Car tyres and high-voltage cables are just two such areas. Elastomeric materials, green-state ceramics and food science represent other interesting fields of applications. This part of the book represents a personal but nevertheless extensive compilation of modern applications. As a matter of course the MOUSE is presented, a portable permanent-magnet based NMR developed by Blümich and his co-workers. Thus the book is not only of interest to NMR spectroscopists but also to people in material science and chemical engineering. The bibliography and indexing are excellent and may serve as an attractive reference source for NMR spectroscopists. The book is the first on the subject and likely to become the standard text for NMR imaging of materials as the books by Abragam, Slicher and Ernst et al are for NMR spectroscopy. The purchase of this beautiful book for people dealing with NMR spectroscopy or medical MRI is highly recommended. Ralf Ludwig

  10. Mobile NMR for analysis of polyethylene pipes

    International Nuclear Information System (INIS)

    NMR relaxometry is a suitable tool to determine the morphology of semi-crystalline polymers by its ability to discriminate between rigid, mostly crystalline and soft, usually amorphous material. The NMR-MOUSE (nuclear magnetic resonance mobile universal surface explorer) was explored in this work to supply morphological data of poly(ethylene) pipes nondestructively. PE-100 pipes were investigated in the new state, after squeezing them flat, and after annealing well below the glass temperature. Furthermore, the change in morphology induced by a pressure load from the inside and a point load from the outside was investigated as a function of depth, and the morphology change across a welding line was imaged. A shear-band was detected by destructive high-field NMR imaging in an area of severe deformation of a pipe, where an anomalous depths profile was observed by the NMR-MOUSE. These results demonstrate that the NMR-MOUSE is a suitable tool for non-destructive state assessment of polymer pipes on the basis of laboratory reference data. (author)

  11. Nuclear magnetic resonance (NMR): principles and applications

    International Nuclear Information System (INIS)

    The basis for the phenomenon of nuclear magnetic resonance (NMR) is the ability of certain nuclei possessing both intrinsic angular momentum or ''spin'' I and magnetic moment to absorb electromagnetic energy in the radio frequency range. In principle, there are approximately 200 nuclei which may be investigated using the NMR technique. The NMR spectrum consists of intensity peaks along an axis calibrated in terms of the steady magnetic field or the frequency of the radiofrequency electromagnetic radiation. Analysis of the number, spacing, position and intensity of the lines in an NMR spectrum consists of intensity peaks along an axis calibrated in terms of the steady magnetic field or the frequency of the radiofrequency electromagnetic radiation. Analysis of the number, spacing, position and intensity of the lines in an NMR spectrum provides a variety of qualitative and quantitative analytical applications. The most obvious applications consist of the measurements of nuclear properties, such as spin number and nuclear magnetic moment. In liquids, the fine structure of resonance spectra provides a tool for chemical identification and molecular structure analysis. Other applications include the measurements of self-diffusion coefficients, magnetic fields and field homogeneity, inter-nuclear distances, and, in some cases, the water content of biological materials. (author)

  12. NMR methodologies in the analysis of blueberries.

    Science.gov (United States)

    Capitani, Donatella; Sobolev, Anatoly P; Delfini, Maurizio; Vista, Silvia; Antiochia, Riccarda; Proietti, Noemi; Bubici, Salvatore; Ferrante, Gianni; Carradori, Simone; De Salvador, Flavio Roberto; Mannina, Luisa

    2014-06-01

    An NMR analytical protocol based on complementary high and low field measurements is proposed for blueberry characterization. Untargeted NMR metabolite profiling of blueberries aqueous and organic extracts as well as targeted NMR analysis focused on anthocyanins and other phenols are reported. Bligh-Dyer and microwave-assisted extractions were carried out and compared showing a better recovery of lipidic fraction in the case of microwave procedure. Water-soluble metabolites belonging to different classes such as sugars, amino acids, organic acids, and phenolic compounds, as well as metabolites soluble in organic solvent such as triglycerides, sterols, and fatty acids, were identified. Five anthocyanins (malvidin-3-glucoside, malvidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-galactoside, and petunidin-3-glucoside) and 3-O-?-l-rhamnopyranosyl quercetin were identified in solid phase extract. The water status of fresh and withered blueberries was monitored by portable NMR and fast-field cycling NMR. (1) H depth profiles, T2 transverse relaxation times and dispersion profiles were found to be sensitive to the withering. PMID:24668393

  13. Nuclear magnetic resonance (NMR) blood flow imaging

    International Nuclear Information System (INIS)

    Picture element values in NMR images are dependent not only upon T/sub 1/ and T/sub 2/ relaxation times but also on the local density and velocity of hydrogen nuclei moving through the region being imaged. In 1959 the potential of non-imaging NMR for measuring blood flow was demonstrated. Recently several investigators have proposed methods for combining NMR imaging with NMR blood flow measurements. The authors have investigated the relationships between various radiofrequency pulse sequences and flow rate and their effects on image intensity using a constant flow pump and a 0.5 Tesla Technicare Teslacon NMR imager. Dilute mixtures of ethylene glycol were used to simulate blood. Flow measurements were made in Tygon Tubing (12 mm) at variable velocities ranging from 0-35 cm/sec. The flow phantom was used to calibrate several pulse sequences relating image intensity and vascular flow velocity. Representative patient studies demonstrating blood-flow have been performed. The calibration is being extended to pulsatile flow systems

  14. Structural fidelity and NMR relaxation analysis in a prototype RNA hairpin.

    Science.gov (United States)

    Giamba?u, George M; York, Darrin M; Case, David A

    2015-05-01

    RNA hairpins are widespread and very stable motifs that contribute decisively to RNA folding and biological function. The GTP1G2C3A4C5U6U7C8G9G10U11G12C13C14 construct (with a central UUCG tetraloop) has been extensively studied by solution NMR, and offers and excellent opportunity to evaluate the structure and dynamical description afforded by molecular dynamics (MD) simulations. Here, we compare average structural parameters and NMR relaxation rates estimated from a series of multiple independent explicit solvent MD simulations using the two most recent RNA AMBER force fields (ff99 and ff10). Predicted overall tumbling times are ?20% faster than those inferred from analysis of NMR data and follow the same trend when temperature and ionic strength is varied. The Watson-Crick stem and the "canonical" UUCG loop structure are maintained in most simulations including the characteristic syn conformation along the glycosidic bond of G9, although some key hydrogen bonds in the loop are partially disrupted. Our analysis pinpoints G9-G10 backbone conformations as a locus of discrepancies between experiment and simulation. In general the results for the more recent force-field parameters (ff10) are closer to experiment than those for the older ones (ff99). This work provides a comprehensive and detailed comparison of state of the art MD simulations against a wide variety of solution NMR measurements. PMID:25805858

  15. Determination of solid fat content by NMR

    International Nuclear Information System (INIS)

    To establish a standard method for determing solid fat content, the NMR method was tested at six laboratories and the results were examined for collaboration. Two types of instruments, pulse NMR and wide-line NMR were used. Standard deviation in results at six laboratories was less than 1.5 for the step wise method, but more than 1.5 for the rapid method. The standard deviation in results at a single laboratory was much less than either of these cases. No significant difference could be observed in the values obtained using both instruments. Solid fat content values measured for a mixture of fully hydrogenated rapeseed and rapeseed oil agreed well with the percentage of solid by weight. (author)

  16. Characterization by NMR of ozonized methyl linoleate

    International Nuclear Information System (INIS)

    In the present study ozonized methyl linoleate with peroxide index of 1,800 mmol-equiv kg-1 was chemically characterized. Ozonation of methyl linoleate produced hydroperoxides, ozonides and aldehydes which were identified by 1H and 13C NMR two-dimensional. The standard methyl linoleate and ozonized methyl linoleate shown very similar 1H NMR spectra except for the signals at ? 9.7 and ? 9.6 that correspond to aldehydic hydrogen, ? 5.7 and ? 5.5 (olefinic signals from hydroperoxides) and ? 5.2 ppm (multiplet from ozonides methynic hydrogen). Other resonance assignments are based on the connectivities provided by the hydrogen scalar coupling constants. These results indicate that NMR spectroscopy can provide valuable information about the amount of formed oxygenated compounds in the ozonized methyl linoleate in order to use it to follow up ozone therapy and chemistry of ozonized vegetable oil. (author)

  17. Characterization by NMR of ozonized methyl linoleate

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Maritza F. [National Center for Scientific Research, Havana (Cuba). Ozone Research Center. Dept. of Ozonized Substances]. E-mail: maritza.diaz@cnic.edu.cu; Gavin, Jose A. [University of the Laguna, Tenerife (Spain)

    2007-07-01

    In the present study ozonized methyl linoleate with peroxide index of 1,800 mmol-equiv kg{sup -1} was chemically characterized. Ozonation of methyl linoleate produced hydroperoxides, ozonides and aldehydes which were identified by {sup 1}H and {sup 13}C NMR two-dimensional. The standard methyl linoleate and ozonized methyl linoleate shown very similar {sup 1}H NMR spectra except for the signals at {delta} 9.7 and {delta} 9.6 that correspond to aldehydic hydrogen, {delta} 5.7 and {delta} 5.5 (olefinic signals from hydroperoxides) and {delta} 5.2 ppm (multiplet from ozonides methynic hydrogen). Other resonance assignments are based on the connectivities provided by the hydrogen scalar coupling constants. These results indicate that NMR spectroscopy can provide valuable information about the amount of formed oxygenated compounds in the ozonized methyl linoleate in order to use it to follow up ozone therapy and chemistry of ozonized vegetable oil. (author)

  18. Handbook of tritium NMR spectroscopy and applications

    International Nuclear Information System (INIS)

    Following a brief introduction, highlighting the importance of 3H nmr spectroscopy for tritium tracer studies, Chapter 1 deals with the theory of the method, the interpretation of spectra and other experimental aspects, emphasizing the importance of careful sample preparation and the special relationship of 3H nmr spectral detail to the wealth of published data for proton spectra. Chapter 2 reviews the current methods for labelling compounds with tritium and the relationship of observed patterns of labelling to these methods. Chapter 3 describes applications of 3H nmr spectroscopy to research in the life sciences which illustrate the power of the technique. Studies employing this analytical tool have revealed numerous interesting and indeed unexpected results in the behaviour of tritium atoms in labelled molecules. These studies have included applications of tritiated compounds in analytical and biochemical problems, in problems of catalysis and reaction mechanisms, and in other areas of scientific research. (author)

  19. O17 NMR spectra of diphosphatopolyoxomolybdates

    International Nuclear Information System (INIS)

    Aqueous solutions of the salts Na6P2Mo18O62x52H2O(1), Na4H2P2Mo5O23x10H2O(2) and Na6P2Mo5O23x14H2O(3) with concentration 0.2(1), and 0.4(2)(3) mol/l have been studied using NMR method on the 17O and 31P nuclei. Chemical shifts of 17O and 31P NMR of heteropolyanions P2Mo5O236- and P2Mo18O626- are measured. It is shown that chemical shift of 17O NMR in polyoxomolybdate correlates with the distance to the nearest molybdenum atom

  20. Covariance NMR spectroscopy by singular value decomposition

    Science.gov (United States)

    Trbovic, Nikola; Smirnov, Serge; Zhang, Fengli; Brüschweiler, Rafael

    2004-12-01

    Covariance NMR is demonstrated for homonuclear 2D NMR data collected using the hypercomplex and TPPI methods. Absorption mode 2D spectra are obtained by application of the square-root operation to the covariance matrices. The resulting spectra closely resemble the 2D Fourier transformation spectra, except that they are fully symmetric with the spectral resolution along both dimensions determined by the favorable resolution achievable along ?2. An efficient method is introduced for the calculation of the square root of the covariance spectrum by applying a singular value decomposition (SVD) directly to the mixed time-frequency domain data matrix. Applications are shown for 2D NOESY and 2QF-COSY data sets and computational benchmarks are given for data matrix dimensions typically encountered in practice. The SVD implementation makes covariance NMR amenable to routine applications.

  1. NMR with Hyperpolarised Protons in Metals

    International Nuclear Information System (INIS)

    Proton pulse NMR, established as a versatile method in Solid State Physics, Chemistry, Biology and Medical Science, requires on the order of 1018 nuclei to detect an electromagnetic signal in a free induction decay (FID). The main cause for this small sensitivity is the low polarisation in the order of a few ppm due to the Boltzmann distribution in the magnetic field. Thus, NMR experiments on hydrogen are limited to metals with extremely high hydrogen solubility like Pd near room temperature. Using a polarised proton beam, a NMR signal is possible with as few as 1013 implanted nuclei. For the first time spin-spin and spin-lattice relaxation times were measured in Au and W with this technique at the Bonn cyclotron.

  2. NMR-based metabolomics of mammalian cell and tissue cultures

    International Nuclear Information System (INIS)

    NMR spectroscopy was used to evaluate growth media and the cellular metabolome in two systems of interest to biomedical research. The first of these was a Chinese hamster ovary cell line engineered to express a recombinant protein. Here, NMR spectroscopy and a quantum mechanical total line shape analysis were utilized to quantify 30 metabolites such as amino acids, Krebs cycle intermediates, activated sugars, cofactors, and others in both media and cell extracts. The impact of bioreactor scale and addition of anti-apoptotic agents to the media on the extracellular and intracellular metabolome indicated changes in metabolic pathways of energy utilization. These results shed light into culture parameters that can be manipulated to optimize growth and protein production. Second, metabolomic analysis was performed on the superfusion media in a common model used for drug metabolism and toxicology studies, in vitro liver slices. In this study, it is demonstrated that two of the 48 standard media components, choline and histidine are depleted at a faster rate than many other nutrients. Augmenting the starting media with extra choline and histidine improves the long-term liver slice viability as measured by higher tissues levels of lactate dehydrogenase (LDH), glutathione and ATP, as well as lower LDH levels in the media at time points out to 94 h after initiation of incubation. In both models, media components and cellular metabolites are measured over time and correlated wis are measured over time and correlated with currently accepted endpoint measures.

  3. NMR-based metabolomics of mammalian cell and tissue cultures

    Energy Technology Data Exchange (ETDEWEB)

    Aranibar, Nelly; Borys, Michael; Mackin, Nancy A.; Ly, Van; Abu-Absi, Nicholas; Abu-Absi, Susan [Bristol-Myers Squibb Company (United States); Niemitz, Matthias [PERCH Solutions Ltd. (Finland); Schilling, Bernhard; Li, Zheng Jian; Brock, Barry; Russell, Reb J.; Tymiak, Adrienne; Reily, Michael D., E-mail: michael.reily@bms.com [Bristol-Myers Squibb Company (United States)

    2011-04-15

    NMR spectroscopy was used to evaluate growth media and the cellular metabolome in two systems of interest to biomedical research. The first of these was a Chinese hamster ovary cell line engineered to express a recombinant protein. Here, NMR spectroscopy and a quantum mechanical total line shape analysis were utilized to quantify 30 metabolites such as amino acids, Krebs cycle intermediates, activated sugars, cofactors, and others in both media and cell extracts. The impact of bioreactor scale and addition of anti-apoptotic agents to the media on the extracellular and intracellular metabolome indicated changes in metabolic pathways of energy utilization. These results shed light into culture parameters that can be manipulated to optimize growth and protein production. Second, metabolomic analysis was performed on the superfusion media in a common model used for drug metabolism and toxicology studies, in vitro liver slices. In this study, it is demonstrated that two of the 48 standard media components, choline and histidine are depleted at a faster rate than many other nutrients. Augmenting the starting media with extra choline and histidine improves the long-term liver slice viability as measured by higher tissues levels of lactate dehydrogenase (LDH), glutathione and ATP, as well as lower LDH levels in the media at time points out to 94 h after initiation of incubation. In both models, media components and cellular metabolites are measured over time and correlated with currently accepted endpoint measures.

  4. Tailoring broadband inversion pulses for MAS solid state NMR.

    Science.gov (United States)

    Riedel, Kerstin; Herbst, Christian; Leppert, Jörg; Ohlenschläger, Oliver; Görlach, Matthias; Ramachandran, Ramadurai

    2006-08-01

    A simple approach is demonstrated for designing optimised broadband inversion pulses for MAS solid state NMR studies of biological systems. The method involves a two step numerical optimisation procedure and takes into account experimental requirements such as the pulse length, resonance offset range and extent of H(1) inhomogeneity compensation needed. A simulated annealing protocol is used initially to find appropriate values for the parameters that define the well known tanh/tan adiabatic pulse such that a satisfactory spin inversion is achieved with minimum RF field strength. This information is then used in the subsequent stage of refinement where the RF pulse characteristics are further tailored via a local optimisation procedure without imposing any restrictions on the amplitude and frequency modulation profiles. We demonstrate that this approach constitutes a generally applicable tool for obtaining pulses with good inversion characteristics. At moderate MAS frequencies the efficacy of the method is experimentally demonstrated for generating double-quantum NMR spectra via the zero-quantum dipolar recoupling scheme RFDR. PMID:16937242

  5. NMR linewidth and skyrmion localization in quantum hall ferromagnets

    International Nuclear Information System (INIS)

    Full text: The ground state of the two-dimensional electron gas (2DEG) at filling factor one (V = 1) is a spin-polarized state in which all electrons completely fill the lowest Landau level with spin up polarization (quantum Hall ferromagnet). The low lying charged excitation of the 2DEG is called skyrmion, or charged spin texture, and carries an unusual spin distribution. Pictorially, this distribution can be viewed as a conguration in which the spin field points down at a given position and smoothly rotates as one moves radially outwards from that point, until all the spins are polarized as in the ground state. The existence of this many body electronic state was confirmed performing optically pumped nuclear magnetic resonance (OPNMR) measurements of the 71Ga nuclei located in an n-doped GaAs multiple quantum well. As the nuclei of the quantum wells are coupled to the the spins of the 2DEG via the isotropic Fermi contact interaction, the Knight shift (Ks) from the NMR signal gives information about the spin polarization of the 2DEG. It was reported that Ks symmetrically drops around v = 1, showing that the charged excitation of the quantum Hall ferromagnet involves a large number of spin-ips. However, recently new OPNMR measurements in multiple quantum wells were performed at very low temperatures (T = 0:3 K) showing that the Knight shift data around v = 1 consist of a tilted plateau, in contrast to the symmetrical fall atup> in contrast to the symmetrical fall at higher temperatures. As NMR is a local probe, it was argued that the existence of the tilted plateau is related to the localization of the skyrmions. In addition, the full width at half maximum (FWHM) of the OPNMR signal has a non-monotonic temperature dependence at v = 1, increasing when the temperature is lowered up to a critical value and then, falling down. It is well known that the linewidth of the NMR measurements is aected by the dynamics of the nuclei (motional narrowing effect). However, as the 71Ga nuclei are spatially fixed in the GaAs quantum wells, any observed dynamical effect must be related to the dynamics of 2DEG. In particular, if v = 1, those effects should be related to the skyrmion dynamics. Therefore, the present work will be devoted to show that the interplay between skyrmion dynamics and localization effects are enough to explain the NMR profile in the whole range of the experimentally available parameters. (author)

  6. Space-Filling Curves for Quantum Control Parameters

    OpenAIRE

    Shafee, Fariel

    2003-01-01

    We consider the use of space-filling curves (SFC) in scanning control parameters for quantum chemical systems. First we show that a formally exact SFC must be singular in the control parameters, but a finite discrete generalization can be used with no problem. We then make general observations about the relevance of SFCs in preference to linear scans of the parameters. Finally we present a simple magnetic field example relevant in NMR and show from the calculated autocorrela...

  7. 119Sn, 13C and 1H NMR studies of aryloxy- and arylthio(1-butyl)stannanes

    International Nuclear Information System (INIS)

    Two series of compounds were prepared and studied by means of 119 Sn, 13C, and 1H NMR spectroscopy, viz aryloxy-and N-heteroaryloxytris(1-butyl)stannanes and their thio analogues Bu3SnER, and diaryloxy- and di (N-heteroaryloxy)bis(1-butyl)stannanes and their thio analogues Bu2Sn(ER)2, where E means oxygen or sulfur, Bu is 1-butyl, R=phenyl, 1-naphthyl, or 8-quinolyl. Based on a comparison of NMR spectral parameters of both series of organotin compounds, and on a comparison with NMR spectral parameters of analogous, purely organic compounds CH3ER, the consequences are discussed of the presence of tin atoms in the organotin substituents and of nitrogen heteroatoms in the aromatic systems, and the ensuing structure of the organotin compounds is considered. (author). 4 tabs., 31 refs

  8. Applications of NMR spectroscopy to xenobiotic metabolism

    International Nuclear Information System (INIS)

    Recent years have seen high field NMR spectrometers become commonplace in research laboratories. At the same time, major advances in methodology for structural analysis have occurred, particularly notable among these being the development of two-dimensional spectroscopic techniques. Many applications have been made of NMR spectroscopy in the study of xenobiotic metabolic processes. This deals with two specific applications which have been made in the author's laboratory and involve mechanistic studies of the reactions of the carcinogens ethylene dibromide and aflatoxin with DNA

  9. Tritiation methods and tritium NMR spectroscopy

    International Nuclear Information System (INIS)

    We have used a simple process for the production of highly tritiated water and characterized the product species by 1H and 3H NMR spectroscopy. The water is readily manipulated and used in subsequent reactions either as T2O, CH3COOT or CF3COOT. Development of tritiated diimide has progressed to the point where cis-hydrogenated products at 1-20 Ci/mmole S.A. are possible. Tri-n-butyl tin tritide has been produced at >95% tritium content and well characterized by multinuclear NMR techniques. 27 refs., 3 figs

  10. "Shim pulses" for NMR spectroscopy and imaging

    Science.gov (United States)

    Topgaard, Daniel; Martin, Rachel W.; Sakellariou, Dimitris; Meriles, Carlos A.; Pines, Alexander

    2004-12-01

    A way to use adiabatic radiofrequency pulses and modulated magnetic-field gradient pulses, together constituting a "shim pulse," for NMR spectroscopy and imaging is demonstrated. These pulses capitalize on phase shifts derived from probe gradient coils to compensate for nonlinear intrinsic main magnetic field homogeneity for spectroscopy, as well as for deviations from linear gradients for imaging. This approach opens up the possibility of exploiting cheaper, less-than-perfect magnets and gradient coils for NMR applications. adiabatic | modulated gradient | MRI | pulse sequence | numerical optimization

  11. Experience of NMR tomography of the skeleton

    International Nuclear Information System (INIS)

    The value of nuclear magnetic resonance (NMR) tomography in the skeleton is analysed in 27 patients who had been examined by a prototype NMR scanner (resistive magnet, 0.2 Tesla). Anatomical structures and detail can be seen using the spin-echo mode and brief sequences. There is marked contrast difference between normal and abnormal tissues. Pathological changes lead to marked alterations in relaxation times. Inflammatory conditions, tumours and aseptic bone necrosis are demonstrated with a high degree of sensitivity. Tomography in the three geometric planes, with any desired additional plane, shows the extent and localisation of bone abnormalities. (orig.)

  12. NMR characterization of high cis polybutadiene

    International Nuclear Information System (INIS)

    In this work a laboratory scale process was studied for the production of polybutadiene with high content of cis-1,4 repeating units. A Ziegler-Natta catalytic system constituted of neodymium versatate (Nd), tert-butyl chloride (Cl) and an organo aluminium compound (Al) was used. The influence of the organo aluminium (co catalyst) type, Al/Nd and Cl/Nd molar ratios on the polymer microstructure was verified. The polymers microstructures were characterized by 13C nuclear magnetic resonance (NMR). The maximum content of cis-1,4 repeating units determined by 13C-NMR was 97.37%. (author)

  13. NMR characterization of high cis polybutadiene

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, L.A.; Tavares, M.I.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano]. E-mail: mibt@ima.ufrj.br; Coutinho, F.M.B.; Costa, M.A.S. [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Inst. de Quimica

    2004-07-01

    In this work a laboratory scale process was studied for the production of polybutadiene with high content of cis-1,4 repeating units. A Ziegler-Natta catalytic system constituted of neodymium versatate (Nd), tert-butyl chloride (Cl) and an organo aluminium compound (Al) was used. The influence of the organo aluminium (co catalyst) type, Al/Nd and Cl/Nd molar ratios on the polymer microstructure was verified. The polymers microstructures were characterized by {sup 13}C nuclear magnetic resonance (NMR). The maximum content of cis-1,4 repeating units determined by {sup 13}C-NMR was 97.37%. (author)

  14. NMR detection with an atomic magnetometer

    OpenAIRE

    Savukov, I. M.; Romalis, M. V.

    2004-01-01

    We demonstrate detection of NMR signals using a non-cryogenic atomic magnetometer and describe several novel applications of this technique. A water free induction decay (FID) signal in a 0.5 $\\mu$T field is detected using a spin-exchange-relaxation-free K magnetometer and the possibility of using a multi-channel magnetometer for 3-D MRI requiring only a single FID signal is described. We also demonstrate detection of less than $10^{13}$ $^{129}$Xe atoms whose NMR signal is ...

  15. (13)C NMR Metabolomics: INADEQUATE Network Analysis.

    Science.gov (United States)

    Clendinen, Chaevien S; Pasquel, Christian; Ajredini, Ramadan; Edison, Arthur S

    2015-06-01

    The many advantages of (13)C NMR are often overshadowed by its intrinsically low sensitivity. Given that carbon makes up the backbone of most biologically relevant molecules, (13)C NMR offers a straightforward measurement of these compounds. Two-dimensional (13)C-(13)C correlation experiments like INADEQUATE (incredible natural abundance double quantum transfer experiment) are ideal for the structural elucidation of natural products and have great but untapped potential for metabolomics analysis. We demonstrate a new and semiautomated approach called INETA (INADEQUATE network analysis) for the untargeted analysis of INADEQUATE data sets using an in silico INADEQUATE database. We demonstrate this approach using isotopically labeled Caenorhabditis elegans mixtures. PMID:25932900

  16. “In-plant” NMR: Analysis of the Intact Plant Vesicularia dubyana by High Resolution NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Viktor P. Kutyshenko

    2015-03-01

    Full Text Available We present here the concept of “in-plant” NMR and show that high-resolution NMR spectroscopy is suitable for the analysis of intact plants and can be used to follow the changes in the intraorganismal molecular composition over long time periods. The NMR-based analysis of the effect of different concentrations of heavy water on the aquatic plant Vesicularia dubyana revealed that due to the presence of specific adaptive mechanisms this plant can sustain the presence of up to 85% of D2O. However, it dies in 100% heavy water.

  17. SPE-NMR metabolite sub-profiling of urine

    OpenAIRE

    Jacobs, D.M.; Spiesser, L.; Garnier, M; Roo, N., de; Dorsten, F., van; Hollebrands, B.; van Velzen, E; Draijer, R; Duynhoven, J.P.M. van

    2012-01-01

    NMR-based metabolite profiling of urine is a fast and reproducible method for detection of numerous metabolites with diverse chemical properties. However, signal overlap in the (1)H NMR profiles of human urine may hamper quantification and identification of metabolites. Therefore, a new method has been developed using automated solid-phase extraction (SPE) combined with NMR metabolite profiling. SPE-NMR of urine resulted in three fractions with complementary and reproducible sub-profiles. The...

  18. Constraining 17O and 27Al NMR spectra of high-pressure crystals and glasses: New data for jadeite, pyrope, grossular, and mullite

    Science.gov (United States)

    Kelsey, K.E.; Stebbins, J.F.; Du, L.-S.; Hankins, B.

    2007-01-01

    The 17O NMR spectra of glasses quenched from melts at high pressure are often difficult to interpret due to overlapping peaks and lack of crystalline model compounds. High-pressure aluminosilicate glasses often contain significant amounts of [5]Al and [6]Al, thus these high-pressure glasses must contain oxygen bonded to high-coordinated aluminum. The 17O NMR parameters for the minerals jadeite, pyrope, grossular, and mullite are presented to assist interpretation of glass spectra and to help test quantum chemical calculations. The 17O NMR parameters for jadeite and grossular support previous peak assignments of oxygen bonded to Si and high-coordinated Al in high-pressure glasses as well as quantum chemical calculations. The oxygen tricluster in mullite is very similar to the previously observed tricluster in grossite (CaAl4 O7) and suspected triclusters in glasses. We also present 27Al NMR spectra for pyrope, grossular, and mullite.

  19. The complete 51V MAS NMR spectrum of surface vanadia nanoparticles on anatase (TiO2): vanadia surface structure of a DeNOx catalyst.

    Science.gov (United States)

    Nielsen, Ulla Gro; Topsøe, Nan-Yu; Brorson, Michael; Skibsted, Jørgen; Jakobsen, Hans J

    2004-04-21

    The first observations of the complete manifold of spinning sidebands (ssbs) including both the central and satellite transitions in (51)V MAS NMR spectra of surface vanadia nanoparticles on titania in DeNO(x) catalysts are presented. (51)V quadrupole coupling and chemical shift anisotropy parameters for the dominating vanadia structure are determined from (51)V MAS NMR spectra recorded at 9.4 and 14.1 T. Based on correlations previously established between (51)V NMR parameters and crystal structure data for inorganic vanadates, the NMR data are consistent with vanadium in a distorted octahedral oxygen coordination environment for the so-called strongly bonded vanadia species on the surface. The investigation includes two vanadia-titania model catalysts and six industrial-type DeNO(x) catalysts. PMID:15080698

  20. Effect of Ancillary Ligand on Electronic Structure as Probed by 51V Solid-State NMR Spectroscopy for Vanadium-o-Dioxolene Complexes

    OpenAIRE

    Goncharova-zapata, Olga; Chatterjee, Pabitra B.; Hou, Guangjin; Quinn, Laurence L.; Li, Mingyue; Yehl, Jenna; Crans, Debbie C.; Polenova, Tatyana

    2013-01-01

    A series of vanadium(V) complexes with o-dioxolene (catecholato) ligands and an ancillary ligand, (N-(salicylideneaminato)ethylenediamine) (hensal), were investigated using 51V solid-state magic angle spinning NMR spectroscopy (51V MAS NMR) to assess the local environment of the vanadium(V). The solid-state 51V NMR parameters of vanadium(V) complexes with a related potentially tetradentate ancillary ligand (N-salicylidene-N?-(2-hydroxyethyl)ethylenediamine) (h2shed) were previously shown to...

  1. 17O NMR investigation of phosphite hydrolysis mechanisms.

    Science.gov (United States)

    McIntyre, Sarah K; Alam, Todd M

    2007-12-01

    The use of solution 17O NMR spectroscopy in verifying the mechanism of trialkyl phosphite hydrolysis is presented. Trimethyl phosphite was reacted with 17O-labeled H2O at different temperatures and two reactant concentrations, with the reaction being monitored by 17O NMR. Kinetic details elucidated from the NMR spectra are also discussed. PMID:18044801

  2. Analysis of polymorphism in pharmaceutical solids: Toward NMR crystallography.

    Czech Academy of Sciences Publication Activity Database

    Brus, Ji?í; Urbanová, Martina; Czernek, Ji?í

    Ljubljana : Slovenian NMR Centre, 2006. s. 51. [Frontiers of Biomolecular NMR. 30.06.2006-01.07.2006, Ljubljana] R&D Projects: GA AV ?R IAA400500602 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymorphism * NMR spectroscopy Subject RIV: CD - Macromolecular Chemistry

  3. Shape-independent model (SHIM) approach for studying aggregation by NMR diffusometry

    Science.gov (United States)

    Hernandez Santiago, Adrian A.; Buchelnikov, Anatoly S.; Rubinson, Maria A.; Yesylevskyy, Semen O.; Parkinson, John A.; Evstigneev, Maxim P.

    2015-03-01

    NMR diffusometry has been gaining wide popularity in various areas of applied chemistry for investigating diffusion and complexation processes in solid and aqueous phases. To date, the application of this method to study aggregation phenomena proceeding beyond the dimer stage of assembly has been restricted by the need for a priori knowledge of the aggregates' shape, commonly difficult to know in practice. We describe here a comprehensive analysis of aggregation parameter-dependency on the type and shape selected for modeling assembly processes, and report for the first time a shape-independent model (designated the SHIM approach), which may be used as an alternative in cases when information on aggregates' shapes is unavailable. The model can be used for determining equilibrium aggregation parameters from self-diffusion NMR data including equilibrium self-association constant and changes in enthalpy, ?H, and entropy, ?S.

  4. Clinical application and evaluation of the diagnostic significance of NMR-tomography

    International Nuclear Information System (INIS)

    Aim of the project was the clinical application and evaluation of the diagnostic significance of NMR-tomography. About 3 000 patients have been examined especially with diseases of the brain. In 75% of all cases pathological findings could be detected. A subgroup of these patients was used for comprehensive studies with regard to tissue characterization based on the calculation of relaxation time parameters. With methods of image processing and classification techniques we tried to get a clear correlation between combined NMR-parameters and human tissue types. The results show that this procedure is able to improve the detectibility and the association to finding groups and tumorgradings in certain cases. (orig./ECB) With 134 refs., 17 tabs., 86 figs

  5. Crystallinity and compositional changes in carbonated apatites: Evidence from {sup 31}P solid-state NMR, Raman, and AFM analysis

    Energy Technology Data Exchange (ETDEWEB)

    McElderry, John-David P.; Zhu, Peizhi [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Mroue, Kamal H. [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Xu, Jiadi [Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Pavan, Barbara [Department of Chemistry and Science of Advanced Materials Program, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Fang, Ming [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Zhao, Guisheng; McNerny, Erin; Kohn, David H.; Franceschi, Renny T. [School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Holl, Mark M.Banaszak [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Tecklenburg, Mary M.J., E-mail: mary.tecklenburg@cmich.edu [Department of Chemistry and Science of Advanced Materials Program, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Ramamoorthy, Ayyalusamy [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Morris, Michael D. [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States)

    2013-10-15

    Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and {sup 31}P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse {sup 31}P NMR linewidth and inverse Raman PO{sub 4}{sup 3?}?{sub 1} bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3–10.3 wt% CO{sub 3}{sup 2?} range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the {sup 31}P NMR chemical shift frequency and the Raman phosphate ?{sub 1} band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals. - Graphical abstract: Carbonated apatite shows an abrupt change in spectral (NMR, Raman) and morphological (AFM) properties at a composition of about one carbonate substitution per unit cell. Display Omitted - Highlights: • Crystallinity (XRD), particle size (AFM) of carbonated apatites and bone mineral. • Linear relationships among crystallinity, {sup 31}P NMR and Raman inverse bandwidths. • Low and high carbonated apatites use different charge-balancing ion-loss mechanism.

  6. Crystallinity and compositional changes in carbonated apatites: Evidence from 31P solid-state NMR, Raman, and AFM analysis

    International Nuclear Information System (INIS)

    Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO43??1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3–10.3 wt% CO32? range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ?1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals. - Graphical abstract: Carbonated apatite shows an abrupt change in spectral (NMR, Raman) and morphological (AFM) properties at a composition of about one carbonate substitution per unit cell. Display Omitted - Highlights: • Crystallinity (XRD), particle size (AFM) of carbonated apatites and bone mineral. • Linear relationships among crystallinity, 31P NMR and Raman inverse bandwidths. • Low and high carbonated apatites use different charge-balancing ion-loss mechanism

  7. Antiferromagnetism Induced in the Vortex Core of Tl2Ba2CuO6++? Probed by Spatially-Resolved 205Tl-NMR

    International Nuclear Information System (INIS)

    Magnetism in the vortex core state has been studied by spatially-resolved NMR. The nuclear spin lattice relaxation rate T1-1 of 205Tl in nearly optimal-doped Tl2Ba2CuO6+? (Tc=85 K) is significantly enhanced in the vortex core region. The NMR results suggest that the suppression of the d-wave superconducting order parameter in the vortex core leads to the nucleation of islands with local antiferromagnetic (AF) order. (author)

  8. Genetic algorithms and solid state NMR pulse sequences

    CERN Document Server

    Bechmann, Matthias; Sebald, Angelika

    2013-01-01

    The use of genetic algorithms for the optimisation of magic angle spinning NMR pulse sequences is discussed. The discussion uses as an example the optimisation of the C7 dipolar recoupling pulse sequence, aiming to achieve improved efficiency for spin systems characterised by large chemical shielding anisotropies and/or small dipolar coupling interactions. The optimised pulse sequence is found to be robust over a wide range of parameters, requires only minimal a priori knowledge of the spin system for experimental implementations with buildup rates being solely determined by the magnitude of the dipolar coupling interaction, but is found to be less broadbanded than the original C7 pulse sequence. The optimised pulse sequence breaks the synchronicity between r.f. pulses and sample spinning.

  9. Novel fast imaging techniques for diagnostic NMR imaging

    International Nuclear Information System (INIS)

    The dissertation deals with a methodological enhancement of a fast MR imaging technique, the snapshot-FLASH (fast low-angle shot) technique. The first and primary goal was to optimize the snapshot-FLASH technique with a view to its application for diagnostic imaging of the heart. This optimization was to achieve a further reduction of measuring time per single shot and an increase in information gained per time unit. Another very important goal was to improve the method towards more exact, faster and as efficient as possible measurement of n.m.r. parameters. With these goals in mind, new two- or three-dimensional versions and a multilayered version of the snapshot-FLASH imaging sequence were developed. The results obtained in practice are explained and discussed. (orig./DG)

  10. Al NMR: a novel NMR data processing program optimized for sparse sampling

    International Nuclear Information System (INIS)

    Sparse sampling in biomolecular multidimensional NMR offers increased acquisition speed and resolution and, if appropriate conditions are met, an increase in sensitivity. Sparse sampling of indirectly detected time domains combined with the direct truly multidimensional Fourier transform has elicited particular attention because of the ability to generate a final spectrum amenable to traditional analysis techniques. A number of sparse sampling schemes have been described including radial sampling, random sampling, concentric sampling and variations thereof. A fundamental feature of these sampling schemes is that the resulting time domain data array is not amenable to traditional Fourier transform based processing and phasing correction techniques. In addition, radial sampling approaches offer a number of advantages and capabilities that are also not accessible using standard NMR processing techniques. These include sensitivity enhancement, sub-matrix processing and determination of minimal sets of sampling angles. Here we describe a new software package (Al NMR) that enables these capabilities in the context of a general NMR data processing environment.

  11. Demixing of severely overlapping NMR spectra through multiple-quantum NMR.

    Science.gov (United States)

    Manjunatha Reddy, G N; Caldarelli, Stefano

    2010-04-15

    We introduce an NMR method to help in the analysis of complex mixtures. The spectra of molecular fragments are obtained as the traces of a correlation spectrum of the regular (1)H NMR spectrum on one dimension with the one of the highest possible (1)H multiple-quantum (MaxQ) order. As this latter is a function of the number of distinguishable protons in a given molecular fragment, the analysis of a series of multiple-quantum spectra is required to achieve a complete assignment. This MaxQ NMR approach is likely to perform best in the case of signals concentrated in a very narrow frequency range, which is a challenging situation commonly encountered in many relevant analytical problems such as the characterization of extraction fractions (oil, plants, tissues), biological fluids, or environmentally relevant samples. As a demonstration, we apply the MaxQ NMR analysis to a mixture of 11 poly- and monocyclic aromatic hydrocarbons. PMID:20329747

  12. High-resolution NMR structure of an RNA model system: the 14-mer cUUCGg tetraloop hairpin RNA.

    Science.gov (United States)

    Nozinovic, Senada; Fürtig, Boris; Jonker, Hendrik R A; Richter, Christian; Schwalbe, Harald

    2010-01-01

    We present a high-resolution nuclear magnetic resonance (NMR) solution structure of a 14-mer RNA hairpin capped by cUUCGg tetraloop. This short and very stable RNA presents an important model system for the study of RNA structure and dynamics using NMR spectroscopy, molecular dynamics (MD) simulations and RNA force-field development. The extraordinary high precision of the structure (root mean square deviation of 0.3 A) could be achieved by measuring and incorporating all currently accessible NMR parameters, including distances derived from nuclear Overhauser effect (NOE) intensities, torsion-angle dependent homonuclear and heteronuclear scalar coupling constants, projection-angle-dependent cross-correlated relaxation rates and residual dipolar couplings. The structure calculations were performed with the program CNS using the ARIA setup and protocols. The structure quality was further improved by a final refinement in explicit water using OPLS force field parameters for non-bonded interactions and charges. In addition, the 2'-hydroxyl groups have been assigned and their conformation has been analyzed based on NOE contacts. The structure currently defines a benchmark for the precision and accuracy amenable to RNA structure determination by NMR spectroscopy. Here, we discuss the impact of various NMR restraints on structure quality and discuss in detail the dynamics of this system as previously determined. PMID:19906714

  13. 93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20

    Science.gov (United States)

    Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

    2015-03-01

    We report a study of 93Nb- and 27Al-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a praseodymium based compound PrNb2Al20. The observed NMR line at around 3 T and 30 K shows a superposition of typical powder patterns of one Nb signal and at least two Al signals. 93Nb-NMR line could be reproduced by using the previously reported NQR frequency ?Q ? 1.8MHz and asymmetry parameter ? ? 0 [Kubo T et al 2014 JPS Conf. Proc. 3 012031]. From 27Al-NMR/NQR, NQR parameters are obtained to be ?Q,A ? 1.53 MHz, and ?A ? 0.20 for the site A, and ?Q,B ? 2.28 MHz, and ?B ? 0.17 for the site B. By comparing this result with the previous 27Al-NMR study of PrT2Al20 (T = Ti, V) [Tokunaga Y et al 2013 Phys. Rev. B 88 085124], these two Al site are assigned to the two of three crystallographycally inequivalent Al sites.

  14. Crystallinity and compositional changes in carbonated apatites: Evidence from 31P solid-state NMR, Raman, and AFM analysis

    Science.gov (United States)

    McElderry, John-David P.; Zhu, Peizhi; Mroue, Kamal H.; Xu, Jiadi; Pavan, Barbara; Fang, Ming; Zhao, Guisheng; McNerny, Erin; Kohn, David H.; Franceschi, Renny T.; Holl, Mark M. Banaszak; Tecklenburg, Mary M.J.; Ramamoorthy, Ayyalusamy; Morris, Michael D.

    2013-01-01

    Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO43? ?1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3–10.3 wt% CO32? range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ?1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals. PMID:24273344

  15. NMR based geographical characterization of roasted coffee.

    Science.gov (United States)

    Consonni, Roberto; Cagliani, Laura Ruth; Cogliati, Clelia

    2012-01-15

    The increasing attention for food quality and safety led to develop several analytical techniques suitable to address these demands. Coffee has been already demonstrated to represent a worldwide appreciated beverage and its high economical value could induce frauds or adulteration practices involving both compositional and geographical aspects. In the last years, metabolic profiling revealed to be suitable to face the quality determination of food matrices and NMR confirmed its potentiality in metabolites characterization. The present study reports the capability of NMR spectroscopy to investigate the metabolite content of roasted Coffea arabica samples from the three main production areas, America, Africa and Asia. OPLS-DA models performed on (1)H NMR data led to a clear separation of samples according to their origin: fatty acids, chlorogenic acids and lactate and finally acetate and trigonelline resulted the main compounds characterizing the American, African and Asian samples respectively. The analytical approach here presented confirmed the potentiality of the joined NMR analysis and statistical treatments in quality determination of food matrices. PMID:22265520

  16. Hyperpolarized NMR Probes for Biological Assays

    Directory of Open Access Journals (Sweden)

    Sebastian Meier

    2014-01-01

    Full Text Available During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments.

  17. 57Fe NMR study of manganese ferrites.

    Czech Academy of Sciences Publication Activity Database

    Chlan, V.; Procházka, V.; Št?pánková, H.; Sedlák, B.; Novák, Pavel; Šimša, Zden?k; Brabers, V.A.M.

    2008-01-01

    Ro?. 320, ?. 11 (2008), e96-e99. ISSN 0304-8853 R&D Projects: GA ?R GA202/06/0051 Institutional research plan: CEZ:AV0Z10100521 Keywords : manganate ferrites * NMR Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2008

  18. Pharmacological studies of cerebral edema by NMR

    International Nuclear Information System (INIS)

    Wistar male rats have been orally administered 2 mg.kg-1j-1 of triethyltin (TET) chloride for 5 consecutive days. The results was a cerebral edema which constituted a reproducible and useful experimental model for pharmacological screening of drugs used in ageing. Water content modifications and clinical behaviour for 11 days from the beginning of experiment have been linked to T1 and T2 proton relaxation times measured by nuclear magnetic resonance (1H-NMR). The observation of 3 central nervous system structures, which differ in white matter content, has lead to the conclusion that NMR is a more sensitive technique to follow up the edema evolution than the water content measurement alone; it has also allowed to discriminate intra from extra-cellular edema (osmotic and TET edema), and has proved the action of two drugs which are used in aging process treatment on the TET edema (dihydroergotoxine 2x10 mg.kg-1j-1 and (-) eburnamonine 2x50 mg.kg-1j-1). In the future the mastery of this technology will be used to study other nuclei (Na, K, P) which will bring more physiopathological informations and to pharmacological investigations of the brain by NMR tomography or focalised NMR

  19. Method of producing images by NMR techniques

    International Nuclear Information System (INIS)

    The patent relates to methods of producing images of samples by NMR techniques. The method involves free induction signals, which are generated by gyro-magnetically excited nuclei in a sample. Fourier transformation of the signals yields the image. (U.K.)

  20. NMR and Ms studies of miscellaneous hydrodisulfides

    International Nuclear Information System (INIS)

    Syntheses of five alkyl and arylalkyl hydrodisulfides were designed, and three hydrodisulfides were newly obtained. Methyl and ethyl hydrodisulfides as well as the three were subjected to nmr spectroscopic analysis, and the date were compared with those of thiols and other hydrodisulfides. Ms spectra of representative hydrodisulfides were also measured. (author)

  1. Minimising research bottlenecks by decluttering NMR spectra.

    Science.gov (United States)

    Aguilar, Juan A; Cassani, Julia; Delbianco, Martina; Adams, Ralph W; Nilsson, Mathias; Morris, Gareth A

    2015-04-20

    The lack of resolving power in everyday NMR produces ambiguous data, causing bottlenecks, lengthening multi-step projects and increasing the likelihood of making mistakes. Significant impacts can be made in many fields by minimising these problems with the aid of pure shift techniques. PMID:25756360

  2. Novel NMR Method for Organic Aerosol Analysis.

    Czech Academy of Sciences Publication Activity Database

    Horník, Št?pán

    Prague : Institute of Chemical Process Fundamental of the CAS, v. v. i, 2015 - (Bendová, M.; Wagner, Z.), s. 20-21 ISBN 978-80-86186-70-2. [Bažant Postgraduate Conference 2015. Prague (CZ)] Institutional support: RVO:67985858 Keywords : nmr method * organic aerosol composition * analysis Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Responsibilities of NMR application in research

    International Nuclear Information System (INIS)

    NMR investigations in clinical and/or scientific studies may be covered by different radiation protection regulations and legal liability responsibilities. The following topics are discussed: incidental findings, applicability to the situation in radiological hospitals, explicit abandonment of probands/patients, liability of the clinic, liability with respect to contrast agent administration, creation of additional imaging, attendance of radiologists, information requirements.

  4. NMR analysis of a fluorocarbon copolymer

    International Nuclear Information System (INIS)

    Vinylidene fluoride (VF2) can be copolymerized with chlorotrifluoroethylene (CTFE) in an aqueous emulsion using a peroxide chain initiator. The physical properties of the resulting fluorocarbon polymer depend on the ratio of VF2 to CTFE and the randomness of the copolymerization. When CTFE and VF are polymerized in an approximately 3:1 mole ratio, the resulting polymer is soluble in acetone (and other solvents) at room temperature. Using proton and fluorine-19 NMR, the mole ratio of CTFE to VF2, the emulsifier (perfluorodecanoate) concentration, and the randomness of copolymerization can be determined. A trifluorotoluene internal standard is added to a d6-acetone solution of the fluoropolymer. Proton NMR is used to determine the amount of VF2. Fluorine-19 NMR is used to measure the amount of emulsifier and the randomness of copolymerization. Each analysis requires about 5 minutes, and is quite precise, with relative standard deviations from 3 to 10% (10 replicates analyzed). In addition, the results from NMR analyses agree well with wet chemical analyses. 4 refs., 3 figs., 3 tabs

  5. Proton NMR studies on Megasphaera elsdenii flavodoxin: structure elucidation by 2D-NMR and implications.

    OpenAIRE

    Mierlo, C. P. M.

    1990-01-01

    1H NMR techniques have been applied for a thorough study of the uncrystallizable Megasphaera elsdenii flavodoxin in its three redox states. The aim of the research project described in this thesis was to obtain answers regarding questions concerning the redox potential regulation of FMN by the protein and the observed activation barrier occurring between the oxidized and one-electron reduced redox states of the protein. Detailed information about the structure of the, from a NMR point of view...

  6. Insights into the local residual entropy of proteins provided by NMR relaxation.

    OpenAIRE

    Li, Z.; Raychaudhuri, S.; Wand, A. J.

    1996-01-01

    A simple model is used to illustrate the relationship between the dynamics measured by NMR relaxation methods and the local residual entropy of proteins. The expected local dynamic behavior of well-packed extended amino acid side chains are described by employing a one-dimensional vibrator that encapsulates both the spatial and temporal character of the motion. This model is then related to entropy and to the generalized order parameter of the popular "model-free" treatment often used in the ...

  7. Substituent effects on the 13C-NMR spectra of E-3-arylideneflavanones

    International Nuclear Information System (INIS)

    Substituent effects on the 13C-NMR spectra of eleven E-3-arylideneflavanones have been investigated. The influence of the conformation of the hetero ring and other steric interactions on the transmission mechanism are discussed. Chemical shifts of the C-? and C-#betta# atoms have been correlated with the Hammett sigma-type parameters and have been analysed on the basis of the Swain-Lupton equation. (author)

  8. NMR of 51V and semiconductor-metal phase transition in vanadium dioxide

    International Nuclear Information System (INIS)

    The parameters characterizing electron-nuclear interactions in vanadium dioxide have been determined using the results of measurement of the 51V NMR. Quantitative measurements of relative phase content with the metallic and semiconductor conductivity close to the phase transition temperature have been carried out. The data obtained are in agreement with the concept of appearance of metallic phase ''drops'' in a semiconductor phase and do not confirm the assumption of smooth changes in large interphase layers leading to the gradual structure reconstruction

  9. Calculations of NMR properties for sI and sII clathrate hydrates of carbon dioxide

    Science.gov (United States)

    Siuda, Pawe?; Sadlej, Joanna

    2014-03-01

    Nuclear shielding and spin-spin coupling constants (intra- and intermolecular) have been calculated for cages forming sI and sII clathrate hydrates of carbon dioxide (for all atoms of host and guest molecules). Structures of 512, 51262 and 51264 cages have been constructed using neutronographic data and DFT/B3LYP calculations conducted with HuzIII-su3 basis set for NMR parameters determination. Based on those results it is possible to discriminate between CO2 molecules residing in each type of the cage. The analysis of NMR parameters calculated for water molecules is focused on their dependence on geometry of the molecular environment. It is possible to connect changes in NMR parameters with types of H-bond patterns present in cages of hydrates and the strength of H-bonds formed. Moreover, our results show that topologically differentiable water molecules forming cages are characterized by distinct NMR parameters, for example 17O shielding constants for water molecules of different topologies differ by 1.6 and 2.1 ppm for cages 51262 and 51264, respectively. This observation could be confirmed experimentally.

  10. Squid detected NMR and MRI at ultralow fields

    Science.gov (United States)

    Clarke, John (Berkeley, CA); Pines, Alexander (Berkeley, CA); McDermott, Robert F. (Monona, WI); Trabesinger, Andreas H. (London, GB)

    2008-12-16

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  11. NMR characterization of hydrocarbon adsorption on calcite surfaces: A first principles study

    Science.gov (United States)

    Bevilaqua, Rochele C. A.; Rigo, Vagner A.; Veríssimo-Alves, Marcos; Miranda, Caetano R.

    2014-11-01

    The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca2+. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO3 ( {10bar 14} )). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for 43Ca, 13C, and 17O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.

  12. Comprehensive Solid-State NMR Characterization of Electronic Structure in Ditechnetium Heptoxide

    International Nuclear Information System (INIS)

    A relativistic density functional description of the electronic structure of Tc2O7 has been evaluated by comparison with solid state 99Tc and 17O NMR spectroscopic data (the former isotope a weak beta-emitter). Every site in the molecule can be populated by a nucleus with favorable NMR characteristics, providing the rare opportunity to obtain a comprehensive set of chemical shift and electric field gradient tensors for a small molecular transition metal oxide. NMR parameters were computed for the central molecule of a (Tc2O7)17 cluster, using standard ZORA optimized all-electron QZ4P basis sets for the central molecule and DZ basis sets for surrounding atoms. The magnitudes of the predicted tensor principal values appear to be uniformly larger than observed experimentally, but discrepancies were within the accuracy of the approximation methods used. The convergence of calculated and measured NMR data suggests that the theoretical analysis has validity for the quantitative understanding of structural, magnetic, and chemical properties of Tc(VII) oxides.

  13. Comprehensive Solid-State NMR Characterization of Electronic Structure in Ditechnetium Heptoxide

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Herman M.; De Jong, Wibe A.; Sattelberger, Alfred P.; Poineau, Frederic; Czerwinski, Ken

    2010-09-29

    A relativistic density functional description of the electronic structure of Tc2O7 has been evaluated by comparison with solid state 99Tc and 17O NMR spectroscopic data (the former isotope a weak beta-emitter). Every site in the molecule can be populated by a nucleus with favorable NMR characteristics, providing the rare opportunity to obtain a comprehensive set of chemical shift and electric field gradient tensors for a small molecular transition metal oxide. NMR parameters were computed for the central molecule of a (Tc2O7)17 cluster, using standard ZORA optimized all-electron QZ4P basis sets for the central molecule and DZ basis sets for surrounding atoms. The magnitudes of the predicted tensor principal values appear to be uniformly larger than observed experimentally, but discrepancies were within the accuracy of the approximation methods used. The convergence of calculated and measured NMR data suggests that the theoretical analysis has validity for the quantitative understanding of structural, magnetic, and chemical properties of Tc(VII) oxides. The William R. Wiley Environmental Molecular Sciences Laboratory is a U.S. Department of Energy (DOE) national scientific user facility located at Pacific Northwest National Laboratory (PNNL) in Richland, Washington. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  14. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    Energy Technology Data Exchange (ETDEWEB)

    Richards, T.

    1984-09-01

    NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures.

  15. Non-destructive characterization of materials by single-sided NMR

    International Nuclear Information System (INIS)

    The experiments conducted in this work demonstrate the efficiency and sensitivity of single-sided NMR for investigating macromolecular materials on large time and length scales. Elastomers can readily be characterized by unilateral NMR of protons in terms of a variety of parameters, which correlate with the overall molecular mobility. In this way information about the cross-link density, state of cure and strain, the effects of aging and product heterogeneity can obtained. For these purposes, the NMR-MOUSE was used to optimize product development and to monitor product and production quality on-line. The sensor is also suitable for nondestructive probing of the mechanical deformation in cross-linked elastomers. A special magnet design that fits a stress-strain device has been used for complementary investigation of a series of different rubber stripes during mechanical testing. The profile NMR-MOUSE was found to be a unique tool for the characterization of changes induced by the UV irradiation in natural rubber. The aging profiles were interpreted for the first time based on a novel model in which the radiation absorption coefficient depends on the depth in the sample. (orig.)

  16. Non-destructive characterization of materials by single-sided NMR

    Energy Technology Data Exchange (ETDEWEB)

    Goga, Nicolae-Octavian

    2007-08-20

    The experiments conducted in this work demonstrate the efficiency and sensitivity of single-sided NMR for investigating macromolecular materials on large time and length scales. Elastomers can readily be characterized by unilateral NMR of protons in terms of a variety of parameters, which correlate with the overall molecular mobility. In this way information about the cross-link density, state of cure and strain, the effects of aging and product heterogeneity can obtained. For these purposes, the NMR-MOUSE was used to optimize product development and to monitor product and production quality on-line. The sensor is also suitable for nondestructive probing of the mechanical deformation in cross-linked elastomers. A special magnet design that fits a stress-strain device has been used for complementary investigation of a series of different rubber stripes during mechanical testing. The profile NMR-MOUSE was found to be a unique tool for the characterization of changes induced by the UV irradiation in natural rubber. The aging profiles were interpreted for the first time based on a novel model in which the radiation absorption coefficient depends on the depth in the sample. (orig.)

  17. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    International Nuclear Information System (INIS)

    NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures

  18. The Evaluation of Polyethylene/Clay Composite from Solid State NMR

    Directory of Open Access Journals (Sweden)

    Antônio G. Ferreira

    2011-05-01

    Full Text Available Polymeric nanocomposites based on polyethylene (PE and Brazilian natural montmorillonite clay (MN were obtained by melt processing, using a twin-screw extruder. The main objective of this work is focusing on the characterization of composites materials by solid-state nuclear magnetic resonance (NMR. The solid-state NMR measurements were used to observe both polymer matrix (through carbon-13 and hydrogen nuclei and the clay (silicon-29 and aluminum-27. The polymer matrix analyses were carried out applying solid state techniques, such as: cross-polarization magic angle spinning (CPMAS, variable contact time (VCT and by the proton spin-lattice relaxation time in the rotating frame parameter (T1?H, detected from the resolved carbon-13 decay of the VCT experiment and through the determination of spin-lattice relaxation time, T1H (using low field NMR. The clay was analyzed by 29Si and 27Al, employing MAS NMR technique. From those techniques we can have principally response on clay dispersion in the polyethylene matrix, as well as the interactions between both components in the nanostructured material. The T1H response was an important result which showed, that the materials formed, presented different molecular domains (according to the domain size that varied from 25 to 50 nm, measured by relaxation, considering the clay dispersion mode in terms of intercalation and/or exfoliation in the polymer matrix.

  19. Molecular mobility in Medicago truncatula seed during early stage of germination: Neutron scattering and NMR investigations

    Energy Technology Data Exchange (ETDEWEB)

    Falourd, Xavier [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France); Natali, Francesca [CNR-IOM-OGG, c/o Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Peters, Judith [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Université Joseph Fourier UFR PhITEM, BP 53, 38041 Grenoble Cedex 9 (France); Institut de Biologie Structurale, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France); Foucat, Loïc, E-mail: Loic.Foucat@nantes.inra.fr [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France)

    2014-01-15

    Highlights: • Neutron scattering and NMR approaches were used to characterize seed germination. • A parallel between macromolecular motions and water dynamics was established. • Freezing/thawing cycle revealed a hysteresis connected to the seed hydration level. - Abstract: First hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing–thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content.

  20. WebSpectra: Problems in NMR and IR Spectroscopy

    Science.gov (United States)

    From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

  1. Bomb parameters

    International Nuclear Information System (INIS)

    The reconstruction of neutron and gamma-ray doses at Hiroshima and Nagasaki begins with a determination of the parameters describing the explosion. The calculations of the air transported radiation fields and survivor doses from the Hiroshima and Nagasaki bombs require knowledge of a variety of parameters related to the explosions. These various parameters include the heading of the bomber when the bomb was released, the epicenters of the explosions, the bomb yields, and the tilt of the bombs at time of explosion. The epicenter of a bomb is the explosion point in air that is specified in terms of a burst height and a hypocenter (or the point on the ground directly below the epicenter of the explosion). The current reassessment refines the energy yield and burst height for the Hiroshima bomb, as well as the locations of the Hiroshima and Nagasaki hypocenters on the modern city maps used in the analysis of the activation data for neutrons and TLD data for gamma rays. (J.P.N.)

  2. Thermal maturity of type II kerogen from the New Albany Shale assessed by 13C CP/MAS NMR.

    Science.gov (United States)

    Werner-Zwanziger, Ulrike; Lis, Grzegorz; Mastalerz, Maria; Schimmelmann, Arndt

    2005-01-01

    Thermal maturity of oil and gas source rocks is typically quantified in terms of vitrinite reflectance, which is based on optical properties of terrestrial woody remains. This study evaluates 13C CP/MAS NMR parameters in kerogen (i.e., the insoluble fraction of organic matter in sediments and sedimentary rocks) as proxies for thermal maturity in marine-derived source rocks where terrestrially derived vitrinite is often absent or sparse. In a suite of samples from the New Albany Shale (Middle Devonian to the Early Mississippian, Illinois Basin) the abundance of aromatic carbon in kerogen determined by 13C CP/MAS NMR correlates linearly well with vitrinite reflectance. PMID:15589735

  3. Dynamic (1)H NMR studies of hindered internal rotations in the synthesized particular phosphorus ylide: Experimental and theoretical approaches.

    Science.gov (United States)

    Habibi-Khorassani, Sayyed Mostafa; Shahraki, Mehdi; Maghsoodlou, Malek Taher; Erfani, Susan

    2015-06-15

    Dynamic (1)H NMR measurements were performed within the synthesized particular phosphorus ylide involving 4-formylphenyl phenylcarbamate. Four rotational process and thereby parameters were targeted for rotation around the CC, C-C, HCNC and OCNC bonds. The Gibbs free activation energy in CDCl3, ?G(?)exp, was found to be 64±2, 50±2, 41±2 and 63±2, respectively. These findings were compared with related ab initio and DFT results on simulated situation. Theoretical methods tested, were comparable to the present D (1)H NMR data. PMID:25796011

  4. Dynamic 1H NMR studies of hindered internal rotations in the synthesized particular phosphorus ylide: Experimental and theoretical approaches

    Science.gov (United States)

    Habibi-Khorassani, Sayyed Mostafa; Shahraki, Mehdi; Maghsoodlou, Malek Taher; Erfani, Susan

    2015-06-01

    Dynamic 1H NMR measurements were performed within the synthesized particular phosphorus ylide involving 4-formylphenyl phenylcarbamate. Four rotational process and thereby parameters were targeted for rotation around the Cdbnd C, C-C, HCsbnd NC and OCsbnd NC bonds. The Gibbs free activation energy in CDCl3, ?G?exp, was found to be 64 ± 2, 50 ± 2, 41 ± 2 and 63 ± 2, respectively. These findings were compared with related ab initio and DFT results on simulated situation. Theoretical methods tested, were comparable to the present D 1H NMR data.

  5. A unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear resonance and inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Limbach, H.H.; Ulrich, S.; Buntkowsky, G. [Freie Univ. Berlin (Germany). Inst. fuer Organische Chemie; Sabo-Etienne, S.; Chaudret, B. [Toulouse-3 Univ., 31 (France). Lab. de Chimie de Coordination du C.N.R.S.; Kubas, G.J.; Eckert, J. [Los Alamos National Lab., NM (United States)

    1995-08-12

    In this paper a unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) is presented. It is shown that both exchange processes coexist i.e. do not transform into each other although they may dominate the spectra in different temperature ranges. This superposition is the consequence of the incorporation of the tunnel frequency J of the coherent process into the nuclear two-spin hamiltonian of hydrogen pairs which allows to treat the problem using the well known density matrix theory of NMR line-shapes developed by Alexander and Binsch. It is shown that this theory can also be used to predict the line-shapes of the rotational tunneling transitions observed in the INS spectra of transition metal dihydrogen complexes and that both NMR and INS spectra depend on similar parameters.

  6. Spin Hamiltonian of the Highly Frustrated Gd3Ga5O12 Garnet Antiferromagnet

    CERN Document Server

    Yavorskii, T; Gingras, M J P; Yavors'kii, Taras; Enjalran, Matthew; Gingras, Michel J.P.

    2005-01-01

    Gadolinium Gallium Garnet (GGG) is a fascinating magnetic material that displays an ordered phase in an applied magnetic field, but lacks long-range order and shows spin glass behavior in zero field. We investigate GGG in the zero field regime using a variational mean-field theory approach. We reproduce the spin liquid like correlations and the positions of sharp peaks seen in powder neutron diffraction measurements on GGG. Contrary to the current belief, our results speak in favor of a scenario where GGG is on the verge of developing true conventional long-range magnetic order in zero magnetic field.

  7. Theory of the spin Hamiltonian of ClO2 in single crystals of silver chlorate

    International Nuclear Information System (INIS)

    The EPR of ClO2 in gamma irradiated single crystals of AgClO3 was recently observed and the g and A tensors appeared rotated with respect to each other by approximately 60 about one of the molecular axis of ClO2. This effect was studied by considering a crystal field that breaks the C/sub 2v/ symmetry of ClO2. The crystal field was estimated from a point charge model that includes the Ag+ and ClO/sub -/3 ions that are the nearest to the ClO2 fragment. This model gives a good qualitative agreement with the experimental results: It predicts the same axis and direction of rotation that were observed and a value of the angle of rotation between 0.80 and 4.40 (depending on the position of the ClO2 in the crystal lattice). In this model the g tensor is practically unaffected by the crystal fields and the orientation of the ClO2 fragment is consequently determined by the principal axis of this tensor

  8. NMR Quantum Calculations of the Jones Polynomial

    CERN Document Server

    Marx, Raimund; Kauffman, Louis; Lomonaco, Samuel; Spörl, Andreas; Pomplun, Nikolas; Myers, John; Glaser, Steffen J

    2009-01-01

    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 pseudo pure 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 state of the molecule in each case, we are able to estimate the value of the Jones Polynomial for each of the knots.

  9. Nuclear spin noise in NMR revisited

    CERN Document Server

    Ferrand, Guillaume; Luong, Michel; Desvaux, Hervé

    2015-01-01

    The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite, preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a "bump" or as a "dip" superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparison to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the Spin-Noise and Frequency-Shift Tuning Optima.

  10. NMR-Based Diffusion Lattice Imaging

    CERN Document Server

    Laun, Frederik Bernd

    2013-01-01

    Nuclear magnetic resonance (NMR) diffusion experiments are widely employed as they yield information about structures hindering the diffusion process, e.g. about cell membranes. While it has been shown in recent articles, that these experiments can be used to determine the exact shape of closed pores averaged over a volume of interest, it is still an open question how much information can be gained in open systems. In this theoretical work, we show that the full structure information of periodic open systems is accessible. To this end, the so-called 'SEquential Rephasing by Pulsed field-gradient Encoding N Time-intervals' (SERPENT) sequence is used, which employs several diffusion weighting gradient pulses with different amplitudes. The structural information is obtained by an iterative technique relying on a Gaussian envelope model of the diffusion propagator. Two solid matrices that are surrounded by an NMR-visible medium are considered: a hexagonal lattice of cylinders and a cubic lattice of triangles.

  11. (129)Xe NMR of Mesoporous Silicas

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.T.; Asink, R.A.; Kneller, J.M.; Pietrass, T.

    1999-04-23

    The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.

  12. NMR and CD spectral features of thiaheterohelicenes

    International Nuclear Information System (INIS)

    NMR and CD spectral features of a series of thiaheterohelicenes containing alternant thiophene and benzene rings were examined as associated with their helical structures. The terminal ring protons of the thiaheterohelicenes reflected the characteristics of intramolecular overlap of aromatic rings in 1H NMR spectra. With the progression of the helix a sudden chemical shift of the #betta# proton in the end thiophene ring to the higher field occurred, in contrast to carbohelicenes in which the drift of the upfield shift of the corresponding terminal ring proton was gradually suppressed. The CD spectra of thiaheterohelicenes were quite different from those of carbohelicenes. The intensities of the ? and #betta# absorption bands weakened with the progressive annelation, whereas the intensity of the p absorption band gradually increased, accompanied by a successive increase in the anisotropy factor of the band. These facts suggest that the structures of thiaheterohelicenes differ from those of carbohelicenes in having a peculiar distortion of the helix. (author)

  13. Exploring the limits to spatially resolved NMR

    International Nuclear Information System (INIS)

    Recent advances in MRI have demonstrated resolutions down to 1 ?m. Magnetic resonance force microscopy has the potential to reach sensitivity for single nuclear spins. Given these numbers, in vivo imaging of single cells or even biomacromolecules may seem possible. However, for in vivo applications, there are fundamental differences in the contrast mechanisms compared to MRI at macroscopic scales as the length scale of of molecular self-diffusion exceeds that of the spatial resolution on the NMR time scale. Those effects - which are fundamentally different from the echo attenuation in field gradient NMR - even may lead to general limitations on the spatial resolution achievable in aqueous systems with high water content. In our contribution, we explore those effects on a model system in a high-resolution stray-field imaging setup. In addition to experimental results, simulations based on the Bloch-Torrey equation are presented.

  14. Protein structure by solid state NMR

    International Nuclear Information System (INIS)

    The relative orientations (phi, Psi angles) of adjacent peptide bond planes define the secondary and tertiary structure of peptides and proteins. These orientations can be determined solely on the basis of solid state NMR experiments on single crystal or uniaxially oriented samples. Examples include single crystals of peptides and the coat protein of magnetically oriented filamentous bacteriophage where synthetic and biosynthetic labelling make available various 15N and 13C dipole-dipole couplings. Fundamental and overtone 14N NMR measurements can be performed in natural abundance and give quadrapole splitting, second order shift, mutation frequency and dipole-dipole couplings. The general interpretation strategy for translating spectral frequencies and splittings to orientations relies on several computational steps and molecular graphics presentation

  15. NMR imaging of the honeybee brain

    Directory of Open Access Journals (Sweden)

    D. Haddad

    2004-03-01

    Full Text Available NMR microscopy provides non-invasively distinct soft-tissue contrast in small biological samples. We were able to visualize the three-dimensional structure of the honeybee brain in its natural shape in the intact head capsule. Thus, in addition to acquiring detailed information about the shapes and volumes of the different brain compartments, we were able to show their relative orientations toward each other within the head capsule. Since the brain was lightly fixed but not dehydrated, and stayed attached to the head capsule and its internal structures, the NMR experiments exhibited larger volumes and a more natural stereo geometry of the various brain structures compared to confocal laser microscopy experiments on dissected, dehydrated and cleared brains.

  16. HPLC-NMR revisited: Using time-slice HPLC-SPE-NMR with database assisted dereplication

    DEFF Research Database (Denmark)

    Johansen, Kenneth; Wubshet, Sileshi Gizachew

    2013-01-01

    Time based trapping of chromatographically separated compounds on to solid-phase extraction cartridges (SPE) and subsequent elution to NMR-tubes was done to emulate the function of HPLC–NMR for dereplication purposes. Sufficient mass sensitivity was obtained by the use of a state-of-the-art HPLC–SPE–NMR-system with a cryogenically cooled probe head, designed for 1.7 mm NMR-tubes. The resulting 1H NMR spectra (600 MHz) were evaluated against a database of previously acquired and prepared spectra. The in-house developed matching algorithm, based on partitioning of the spectra and allowing for changes in the chemical shifts, is described and the code included as Supplementary Information. Two mixtures of natural products was used to test the approach; one extract of Carthamus oxyacantha (wild safflower) containing an array of spiro compounds and one extract of the endophytic fungus Penicillum namyslowski containing griseofulvin and analogues. The database matching of the resulting spectra positively identified expected compounds, while the number of false positives was few and easily recognized.

  17. Nuclear magnetic resonance apparatus having semitoroidal RF coil for use in topical NMR and NMR imaging

    International Nuclear Information System (INIS)

    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, to enable NMR measurements to be taken from selected regions inside an object, particularly 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 electric field interactions. The coil may be combined with a like orthogonal coil and suitably driven to provide a circularly polarised field; or it may be used in conjunction with a concentrically nested smaller semitoroidal coil to move the maximum field further from the coil assembly. (author)

  18. 3D Reconstruction of NMR Images

    Directory of Open Access Journals (Sweden)

    Pavol Spanik

    2007-01-01

    Full Text Available This paper introduces experiment of 3D reconstruction NMR images scanned from magnetic resonance device. There are described methods which can be used for 3D reconstruction magnetic resonance images in biomedical application. The main idea is based on marching cubes algorithm. For this task was chosen sophistication method by program Vision Assistant, which is a part of program LabVIEW.

  19. First Principles NMR Signatures of Graphene Oxide

    OpenAIRE

    Lu, Ning; Huang, Ying; Li, Haibei; Li, Zhenyu; Yang, Jinlong

    2010-01-01

    Nuclear magnetic resonance (NMR) has been widely used in the graphene oxide (GO) structure study. However, the detailed relationship between its spectroscopic features and the GO structural configuration has remained elusive. Based on first principles $^{13}$C chemical shift calculations using the gauge including projector augmented waves (GIPAW) method, we provide a spectrum-structure connection. Chemical shift of carbon is found to be very sensitive to atomic environment, ...

  20. Impurity Site NMR Relaxation in Unconventional Superconductors

    OpenAIRE

    Matsumoto, Masashige

    2000-01-01

    Impurity nuclear spin relaxation is studied theoretically. A single impurity generates a bound state localized around the impurity atom in unconventional superconductors. With increasing impurity potential, the relaxation rate $T_1^{-1}$ is reduced by the impurity potential. However, it has a peak at low temperatures due to the impurity bound state. The peak disappears at non-impurity sites. The impurity site NMR measurement detecting a local electronic structure just on the...

  1. NMR-Based Diffusion Lattice Imaging

    OpenAIRE

    Laun, Frederik Bernd; Kuder, Tristan Anselm

    2013-01-01

    Nuclear magnetic resonance (NMR) diffusion experiments are widely employed as they yield information about structures hindering the diffusion process, e.g. about cell membranes. While it has been shown in recent articles, that these experiments can be used to determine the exact shape of closed pores averaged over a volume of interest, it is still an open question how much information can be gained in open systems. In this theoretical work, we show that the full structure in...

  2. NMR studies of protein dynamics and structure

    OpenAIRE

    A?de?n, Jo?rgen

    2010-01-01

    Enzymes are extraordinary molecules that can accelerate chemical reactions by several orders of magnitude. With recent advancements in structural biology together with classical enzymology the mechanism of many enzymes has become understood at the molecular level. During the last ten years significant efforts have been invested to understand the structure and dynamics of the actual catalyst (i. e. the enzyme). There has been a tremendous development in NMR spectroscopy (both hardware and puls...

  3. Strange kinetics, porous media, and NMR

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) techniques cover a broad range of length and time scales on which dynamic properties of fluids confined in porous media can be investigated. This report refers to field-cycling NMR relaxometry, field gradient NMR diffusometry and NMR microscopy. The objective was to examine diffusion, hydrodynamic dispersion, flow, and thermal convection under the influence of geometrical confinements and surface interactions in porous media. The anomalous character of these phenomena will be demonstrated and discussed in comparison with computer simulations and theoretical concepts. The first part of this presentation is devoted to nanoporous samples. It is shown that molecular Levy walks along inner surfaces occur under certain conditions. Mutual 'obstruction' of molecules in molecular sieves and zeolites is another source of diffusion anomaly known as single-file diffusion which can be described by Gaussian propagators with a diffusion coefficient depending on time in a certain limit. In the case of polymers confined in narrow artificial tubes of a porous solid matrix, the characteristics of reptation were experimentally verified. The second part mainly refers to 'trapping' effects as a source of anomalous transport characterised by non-Gaussian propagators. Model objects fabricated on the basis of percolation cluster models were examined with respect to flow, diffusion, thermal convection and hydrodynamic dispersion. The elucidation of transport laispersion. The elucidation of transport laws in model systems of well defined and mathematically describable geometries is considered to be a promising way for the exploration of the structure/dynamics relationship in porous media as a long-term objective

  4. Dynamic nuclear polarization surface enhanced NMR spectroscopy

    OpenAIRE

    Aaron J. Rossini; Zagdoun, Alexandre; Lelli, Moreno; Lesage, Anne; Copéret, Christophe; Emsley, Lyndon

    2013-01-01

    Many of the functions and applications of advanced materials result from their interfacial structures and properties. However, the difficulty in characterizing the surface structure of these materials at an atomic level can often slow their further development Solid-state NMR can probe surface structure and complement established surface science techniques, but its low sensitivity often limits its application. Many materials have low surface areas and/or low concentrations of active/surface s...

  5. Video: Proton Nuclear Magnetic Resonance (NMR)

    Science.gov (United States)

    This video, distributed on YouTube by the Royal Society of Chemistry, describes the basic principles of Nuclear Magnetic Resonance. This video is a good primer and would be very useful to supplement introductory lectures on NMR. The video covers the basic theory behind a 1H spectrum and goes through actually acquiring a spectrum. The top-off look of the instrument is useful and how the superconducting magnet is mounted. Running time for the video is 8:43.

  6. Analyzing NMR spectra with the Morlet wavelet

    OpenAIRE

    Suvichakorn, Aimamorn; Antoine, Jean-pierre; 16th European Signal Processing Conference (EUSIPCO 2008)

    2008-01-01

    The time-scale representation of the Morlet wavelet trans- form is studied on characterizing NMR signals. By an an- alytical analysis and simulations, the wavelet shows a satis- factory performance even when a baseline, an additive Gaussian noise and a solvent are presented in the signals. It can also cope with non-Lorentzian lineshapes which commonly occur due to inhomogeneous distribution of molecules in a substance. These results signify the Morlet wavelet transform as a potential tool to ...

  7. Lock-in amplifier for NMR experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zulkarnaen, M.M.; Isaris, R. (Gama Research Centre, Jogyakarta (Indonesia))

    1981-07-01

    Resonance signals of proton Nuclear Magnetic Resonance (NMR) usually become smaller as the liquid sample becomes more viscous. For solid sample, the signals becomes too small to be significantly observed, and generally the signal to noise ratio is less than unity. The idea of constructing a lock-in amplifier is to increase the signal to noise ratio based on a simple design and availability of components. Results of the performance of the equipment applicable to liquid and solid sample are enclosed.

  8. A thermogravimetric and NMR study of ?-aluminas

    International Nuclear Information System (INIS)

    The Na+ tracer diffusion coefficient and the 27Al NMR spin lattice relaxation time in Na ?-alumina display on anomalous temperature dependence near 470 K. These phenomena are related to absorption of water which takes place when the temperature is decreased below 470 K. Water absorption processes in pure and partially substituted ?-aluminas are studied by thermogravimetric analysis. Their effects upon conductivity are qualitatively discussed. (orig.)

  9. NMR imaging of the honeybee brain

    OpenAIRE

    D. Haddad; F. Schaupp; Brandt, R.; G. Manz; Menzel, R.; Haase, A

    2004-01-01

    NMR microscopy provides non-invasively distinct soft-tissue contrast in small biological samples. We were able to visualize the three-dimensional structure of the honeybee brain in its natural shape in the intact head capsule. Thus, in addition to acquiring detailed information about the shapes and volumes of the different brain compartments, we were able to show their relative orientations toward each other within the head capsule. Since the brain was lightly fixed but not dehydrated, and st...

  10. Gradient Decay Measurement in NMR Tomography.

    Czech Academy of Sciences Publication Activity Database

    Kubásek, R.; Gescheidtová, E.; Bartušek, Karel

    Cambridge : Electromagnetics Academy, 2009, s. 1102-1104. ISBN 978-1-934142-10-3. ISSN 1559-9450. [Progress in Electromagnetics Research Symposium 2009 Moscow. Moscow (RU), 18.08.2009-21.08.2009] R&D Projects: GA ?R(CZ) GA102/07/0389 Institutional research plan: CEZ:AV0Z20650511 Keywords : Gradient Decay * NMR Tomography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Action of the multifunctional peptide BP100 on native biomembranes examined by solid-state NMR.

    Science.gov (United States)

    Misiewicz, Julia; Afonin, Sergii; Grage, Stephan L; van den Berg, Jonas; Strandberg, Erik; Wadhwani, Parvesh; Ulrich, Anne S

    2015-04-01

    Membrane composition is a key factor that regulates the destructive activity of antimicrobial peptides and the non-leaky permeation of cell penetrating peptides in vivo. Hence, the choice of model membrane is a crucial aspect in NMR studies and should reflect the biological situation as closely as possible. Here, we explore the structure and dynamics of the short multifunctional peptide BP100 using a multinuclear solid-state NMR approach. The membrane alignment and mobility of this 11 amino acid peptide was studied in various synthetic lipid bilayers with different net charge, fluidity, and thickness, as well as in native biomembranes harvested from prokaryotic and eukaryotic cells. (19)F-NMR provided the high sensitivity and lack of natural abundance background that are necessary to observe a labelled peptide even in protoplast membranes from Micrococcus luteus and in erythrocyte ghosts. Six selectively (19)F-labeled BP100 analogues gave remarkably similar spectra in all of the macroscopically oriented membrane systems, which were studied under quasi-native conditions of ambient temperature and full hydration. This similarity suggests that BP100 has the same surface-bound helical structure and high mobility in the different biomembranes and model membranes alike, independent of charge, thickness or cholesterol content of the system. (31)P-NMR spectra of the phospholipid components did not indicate any bilayer perturbation, so the formation of toroidal wormholes or micellarization can be excluded as a mechanism of its antimicrobial or cell penetrating action. However, (2)H-NMR analysis of the acyl chain order parameter profiles showed that BP100 leads to considerable membrane thinning and thereby local destabilization. PMID:25616492

  12. On the track to silica-supported tungsten oxo metathesis catalysts: input from 17O solid-state NMR.

    Science.gov (United States)

    Merle, Nicolas; Girard, Guillaume; Popoff, Nicolas; De Mallmann, Aimery; Bouhoute, Yassine; Trébosc, Julien; Berrier, Elise; Paul, Jean-François; Nicholas, Christopher P; Del Rosal, Iker; Maron, Laurent; Gauvin, Régis M; Delevoye, Laurent; Taoufik, Mostafa

    2013-09-01

    The grafting of an oxo chloro trisalkyl tungsten derivative on silica dehydroxylated at 700 °C was studied by several techniques that showed reaction via W-Cl cleavage, to afford a well-defined precatalyst for alkene metathesis. This was further confirmed by DFT calculations on the grafting process. (17)O labeling of the oxo moiety of a series of related molecular and supported tungsten oxo derivatives was achieved, and the corresponding (17)O MAS NMR spectra were recorded. Combined experimental and theoretical NMR studies yielded information on the local structure of the surface species. Assessment of the (17)O NMR parameters also confirmed the nature of the grafting pathway by ruling out other possible grafting schemes, thanks to highly characteristic anisotropic features arising from the quadrupolar and chemical shift interactions. PMID:23944270

  13. Earth's field NMR; a surface moisture detector?

    Science.gov (United States)

    Fukushima, Eiichi; Altobelli, Stephen; McDowell, Andrew; Zhang, Tongsheng

    2012-10-01

    Earth's field NMR (EFNMR), being free of magnets, would be an ideal teaching medium as well as a mobile NMR technique except for its weak S/N. The common EFNMR apparatus uses a powerful prepolarization field to enhance the spin magnetization before the experiment. We introduce a coil design geared to larger but manageable samples with sufficient sensitivity without prepolarization to move EFNMR closer to routine use and to provide an inexpensive teaching tool. Our coil consists of parallel wires spread out on a plywood to form a current sheet with the current return wires separated so they will not influence the main part of the coil assembly. The sensitive region is a relatively thin region parallel to the coil and close to it. A single turn of the coil is wound to be topologically equivalent to a figure-8. The two crossing segments in the center of a figure-8 form two of the parallel wires of the flat coil. Thus, a two-turn figure-8 has four crossing wires so its topologically equivalent coil will have four parallel wires with currents in phase. Together with the excellent sensitivity, this coil offers outstanding interference rejection because of the figure-8 geometry. An example of such a coil has 328 parallel wires covering a ˜1 meter square plywood which yields a good NMR signal from 26 liters of water spread out roughly over the area of the coil in less than one minute in a nearby park.

  14. Principles of high resolution NMR in solids

    CERN Document Server

    Mehring, Michael

    1983-01-01

    The field of Nuclear Magnetic Resonance (NMR) has developed at a fascinating pace during the last decade. It always has been an extremely valuable tool to the organic chemist by supplying molecular "finger print" spectra at the atomic level. Unfortunately the high resolution achievable in liquid solutions could not be obtained in solids and physicists and physical chemists had to live with unresolved lines open to a wealth of curve fitting procedures and a vast amount of speculations. High resolution NMR in solids seemed to be a paradoxon. Broad structure­ less lines are usually encountered when dealing with NMR in solids. Only with the recent advent of mUltiple pulse, magic angle, cross-polarization, two-dimen­ sional and multiple-quantum spectroscopy and other techniques during the last decade it became possible to resolve finer details of nuclear spin interactions in solids. I have felt that graduate students, researchers and others beginning to get involved with these techniques needed a book which trea...

  15. NMR properties of petroleum reservoir fluids.

    Science.gov (United States)

    Hirasaki, George J; Lo, Sho-Wei; Zhang, Ying

    2003-01-01

    NMR well logging of petroleum reservoir require the measurement of the NMR response of water, oil, and gas in the pore space of rocks at elevated temperatures and pressures. The viscosity of the oil may range from less than 1 cp to greater than 10,000 cp. Also, the oil and gas are not a single component but rather a broad distribution of components. The log mean T1 and T2 relaxation time of dead (gas free) crude oils are correlated with viscosity/temperature and Larmor frequency. The relaxation time of live oils deviate from the correlation for dead crude oils. This deviation can be correlated with the methane content of the oil. Natural gas in the reservoir has components other than methane. Mixing rules are developed to accommodate components such as ethane, propane, carbon dioxide, and nitrogen. Interpretation of NMR logs uses both relaxation and diffusion to distinguish the different fluids present in the formation. Crude oils have a broad spectrum of components but the relaxation time distribution and diffusion coefficient distribution are correlated. This correlation is used to distinguish crude oil from the response of water in the pores of the rock. This correlation can also be used to estimate viscosity of the crude oil. PMID:12850718

  16. Cutoff-Free Traveling Wave NMR

    CERN Document Server

    Tang, Joel A; Sodickson, Daniel K; Jerschow, Alexej

    2011-01-01

    Recently, the concept of traveling-wave NMR/MRI was introduced by Brunner et al. (Nature 457, 994-992 (2009)), who demonstrated MR images acquired using radio frequency (RF) waves propagating down the bore of an MR scanner. One of the significant limitations of this approach is that each bore has a specific cutoff frequency, which can be higher than most Larmor frequencies of at the magnetic field strengths commonly in use for MR imaging and spectroscopy today. We overcome this limitation by using a central conductor in the waveguide and thereby converting it to a transmission line (TL), which has no cutoff frequency. Broadband propagation of waves through the sample thus becomes possible. NMR spectra and images with such an arrangement are presented and genuine traveling wave behavior is demonstrated. In addition to facilitating NMR spectroscopy and imaging in smaller bores via traveling waves, this approach also allows one to perform multinuclear traveling wave experiments (an example of which is shown), an...

  17. Phosphorus NMR of isolated perfused morris hepatomas

    International Nuclear Information System (INIS)

    The authors are developing techniques for the study of perfused solid tumors by NMR. Tissue-isolated solid hepatomas were grown to 1-2 cm diameter as described previously. The arterial supply was isolated and the tumors perfused (0.5 - 1.0 ml/min) in vitro at 25 C with a 15% suspension of red blood cells in Krebs-Henseliet solution. 31P-NMR spectra were acquired at 162 MHz in a specially-designed NMR probe using a solenoidal coil. Intracellular pH (monitored from the chemical shift of inorganic phosphate) and ATP levels were stable for up to 6 hrs during perfusion. During 30 min of global ischemia, ATP decreased by 75% and pH fell from 7.0 to 6.7. These changes were reversed by 1 hr reperfusion. In addition to ATP and phosphate, the spectra included a large resonance due to phosphomonoesters, as well as peaks consistent with glycerylphosphocholine, glyceryl-phosphoethanolamine, phosphocreatine, NAD, and UDPG. However, the most novel feature of the spectra was the presence of an unidentified peak in the phosphonate region (+ 16.9 ppm). The peak was not present in spectra of muscle, liver, brain, kidney, or fat tissues excised from the same animals. They are presently attempting to identify the compound that gives rise to this peak and to establish its metabolic origin

  18. Origin of NMR shielding in fluorides

    Science.gov (United States)

    Laskowski, Robert; Blaha, Peter

    2012-06-01

    In this work, we analyze in detail the relation between electronic structure and fluorine nuclear magnetic resonance (NMR) shielding in a series of solid state alkali fluorides (LiF, NaF, KF, RbF, and CsF). For that purpose, we use solid-state NMR calculations implemented in the density functional theory full potential wien2k code (APW+lo). Both measurements and calculations show that the NMR shielding varies across the series by approximately 200 ppm. We focus our discussion on an explanation of the origin of the observed trend, and we show that the variation is mainly determined by contributions from “semicore” metal-p and valence F-p bands. More specifically, the trend in fluorine shielding can be related to the small but significant change in the hybridization of these states. A second important ingredient determining the value of the shielding is the presence and position of metal-d states in the unoccupied part of the Kohn-Sham bands. Although the present analysis has been demonstrated for the 19F nucleus in alkali fluorides, the main results are more general and can explain similar trends observed in other solids and for other nuclei.

  19. NMR studies of protein-ligand interactions.

    Science.gov (United States)

    Goldflam, Michael; Tarragó, Teresa; Gairí, Margarida; Giralt, Ernest

    2012-01-01

    Nuclear magnetic resonance (NMR) has evolved into a powerful tool for characterizing protein-ligand interactions in solution under near physiological conditions. It is now frequently harnessed to assess the affinity and specificity of interactions; to identify binding epitopes on proteins and ligands; and to characterize the structural rearrangements induced by binding.The first section of this chapter provides a general overview of the NMR study of protein-ligand interactions. The section is divided according to two main categories of experiments: those based on observing protein signals and those based on observing ligand signals. The next section explains two case studies performed in the authors' laboratory. The first of these deals with the interaction between vascular endothelial growth factor and a peptidic ligand, and includes a detailed protocol of chemical shift perturbation experiments. The second one reports on the interaction between prolyl oligopeptidase and a small molecule as monitored by ligand saturation transfer difference (STD), and illustrates how NMR can be used to confirm binding and to identify the binding epitope of a ligand. PMID:22167678

  20. Structural and Nutritional Properties of Pasta from Triticum monococcum and Triticum durum Species. A Combined (1)H NMR, MRI, and Digestibility Study.

    Science.gov (United States)

    Pasini, Gabriella; Greco, Fulvia; Cremonini, Mauro A; Brandolini, Andrea; Consonni, Roberto; Gussoni, Maristella

    2015-05-27

    The aim of the present study was to characterize the structure of two different types of pasta, namely Triticum turgidum ssp. durum (cv. Saragolla) and Triticum monococcum ssp. monococcum (cv. Monlis), under different processing conditions. MRI analysis and NMR spectroscopy (i.e., T1 and T2 NMR relaxation times and diffusion parameters) were conducted on pasta, and (1)H NMR spectroscopic analysis of the chemical compounds released by pasta samples during the cooking process was performed. In addition, starch digestibility (enzimatically determined) was also investigated. The NMR results indicated that Saragolla pasta has a more compact structure, ascribed to pasta network and in particular to different technological gluten properties, that mainly determine the lower ability of Monlis pasta in binding water. These results correlate well with the lower rate of starch hydrolysis measured for Monlis pasta compared to Saragolla when both are dried at high temperature. PMID:25940450

  1. Computer-intensive simulation of solid-state NMR experiments using SIMPSON

    Science.gov (United States)

    Tošner, Zden?k; Andersen, Rasmus; Stevensson, Baltzar; Edén, Mattias; Nielsen, Niels Chr.; Vosegaard, Thomas

    2014-09-01

    Conducting large-scale solid-state NMR simulations requires fast computer software potentially in combination with efficient computational resources to complete within a reasonable time frame. Such simulations may involve large spin systems, multiple-parameter fitting of experimental spectra, or multiple-pulse experiment design using parameter scan, non-linear optimization, or optimal control procedures. To efficiently accommodate such simulations, we here present an improved version of the widely distributed open-source SIMPSON NMR simulation software package adapted to contemporary high performance hardware setups. The software is optimized for fast performance on standard stand-alone computers, multi-core processors, and large clusters of identical nodes. We describe the novel features for fast computation including internal matrix manipulations, propagator setups and acquisition strategies. For efficient calculation of powder averages, we implemented interpolation method of Alderman, Solum, and Grant, as well as recently introduced fast Wigner transform interpolation technique. The potential of the optimal control toolbox is greatly enhanced by higher precision gradients in combination with the efficient optimization algorithm known as limited memory Broyden-Fletcher-Goldfarb-Shanno. In addition, advanced parallelization can be used in all types of calculations, providing significant time reductions. SIMPSON is thus reflecting current knowledge in the field of numerical simulations of solid-state NMR experiments. The efficiency and novel features are demonstrated on the representative simulations.

  2. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    International Nuclear Information System (INIS)

    NMR imaging, NMR spectroscopy, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the rodent brain after in vivo helium beam irradiation with single doses of 10, 20, 30, and 50 Gy. Two-dimensional Fourier transform spin-echo imaging and saturation recovery with projection reconstruction were used to measure the NMR relaxation parameters. These parameters were correlated with proton spectroscopy and histopathology. Additional high resolution in vitro proton spectroscopy was performed on brain extracts to observe chemical changes that could not be seen in vivo. The major findings from these experiments were that at 4-14 days postirradiation, image intensity and T1 relaxation time decreased on the irradiated side and increased on the nonirradiated side relative to nonirradiated control animals. In vivo surface coil proton spectroscopy methods demonstrated changes in lipid and phosphatidylcholine (p-choline) peaks. In vitro studies of the aqueous fraction of brain extracts showed radiation-induced changes in lactate, 4-aminobutyric acid, and p-choline peak areas. In the organic fraction, radiation-induced changes were observed in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. With histology and Evans blue injections, blood-brain barrier alterations were seen as early as 4 days after a dose of 50 Gy

  3. Using 17O solid-state NMR and first principles calculation to characterise structure and dynamics in inorganic framework materials.

    Science.gov (United States)

    Soleilhavoup, Anne; Hampson, Matthew R; Clark, Stewart J; Evans, John S O; Hodgkinson, Paul

    2007-12-01

    The use of solid-state (17)O NMR to determine local chemical environment and to characterise oxygen dynamics is illustrated in studies of zirconium tungstate, ZrW(2)O(8), and tungsten oxide, WO(3). Simple 1D magic-angle spinning (MAS) NMR allows the chemical environments in ZrW(2)O(8) to be readily characterised, and the use of a combination of one- and two-dimensional experiments to characterise oxygen dynamics in its cubic phase is reviewed. Combining local information about structure and dynamics from NMR with long-range structural information from diffraction allows a comprehensive picture of the material to be developed. Recent work is described that uses first principles calculation of NMR parameters to probe subtle asymmetries in the WO(6) octahedra that form the structural motif in WO(3). NMR is shown to be a highly sensitive probe of local structure, allowing different models derived from high-quality neutron diffraction studies to be distinguished. The density functional theory (DFT) calculations allow clear correlations between (17)O chemical shifts and distortions of the structure to be established. PMID:18157838

  4. Probing the local structural environment of calcium by natural-abundance solid-state 43 Ca NMR

    Science.gov (United States)

    Lin, Zhongjie; Smith, M. E.; Sowrey, F. E.; Newport, R. J.

    2004-06-01

    New natural-abundance 43 Ca magic angle spinning (MAS) NMR data measured at high magnetic field ( 14.1 T ) is presented for a range of crystalline calcium-containing binary and ternary inorganic compounds. The combination of high field, moderate MAS (up to 4.5 kHz ), and large sample volume (a 9.5 mm diameter MAS rotor) means that a good signal-to-noise ratio can generally be obtained in a time ( ˜12 h ) that makes 43 Ca NMR a feasible approach for determining information about calcium siting in a wide range of materials of physical interest. This study greatly increases the number of 43 Ca NMR parameters determined for solid materials in the literature, extending reports to local nearest-neighbor coordinations to other than oxygen. These data show that the isotropic chemical shift range is >250 ppm and typically that the quadrupole interaction is natural-abundance 43 Ca MAS NMR studies to amorphous materials are reported by examining sol-gel prepared calcium silicate materials. The data show that in the initial amorphous mixture at lower temperatures (120 350°C) the calcium environment is more like that in the parent calcium nitrate than a silicate, and that further heat treatment causes very significant broadening of the calcium resonance. The implications of this observation for the use of natural-abundance 43 Ca MAS NMR structural studies of amorphous materials are examined.

  5. NMR spectroscopy of experimentally shocked single crystal quartz: A reexamination of the NMR shock barometer

    Science.gov (United States)

    Fiske, P. S.; Gratz, A. J.; Nellis, W. J.

    1993-01-01

    Cygan and others report a broadening of the Si-29 nuclear magnetic resonance (NMR) peak for synthetic quartz powders with increasing shock pressure which they propose as a shock wave barometer for natural systems. These results are expanded by studying single crystal quartz shocked to 12 and 33 GPa using the 6.5 m two-stage light-gas gun at Lawrence Livermore National Laboratories. Our NMR results differ substantially from those of Cygan and others and suggest that the proposed shock wave barometer may require refinement. The difference in results between this study and that of Cygan and others is most likely caused by different starting materials (single crystal vs. powder) and different shock loading histories. NMR results from single crystal studies may be more applicable to natural systems.

  6. Portable NMR systems for non destructive testing

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) is one of the more recent sensing technologies and has become very popular for its ability to non-invasively probe down to the molecular level the properties of many materials and living organisms. Its greatest impact has been in the areas of chemistry and medical radiology, but now it is being applied to biochemistry, structural biology, and materials science research. In the past ten years, NMR has made significant contributions to horticulture, biotechnology, chemical engineering, petroleum science and food technology and now stands on the threshold of making an impact on environmental monitoring, building technology, and security technology. Traditionally NMR/MRI is performed using laboratory or clinic based superconducting magnets, but now it is moving out into industry in the form of portable permanent magnet based systems. NMR development is being driven by advancements in electronics, computing and magnet technology and so continues to advance in capability and application. In the building industry, it is often necessary to determine the moisture content of concrete so that it can be optimally cured for strength or to know when floor coverings can be applied. Presently the only way to accurately gauge the true moisture content is to use destructive techniques. This is the method that Parrot used to generate the graph shown in figure 1. Typically the industry yardstick of a 'month per inch' is used for estimating the time requirch' is used for estimating the time required before the concrete surface can be covered, but from this data it is clear that even after a year there can still remain a significant amount of moisture. Concrete is inherently porous and so is greatly affected by the environment and the laying process methods. This makes it very difficult to make predictions based on calibrated standards. What is required is a portable instrument that can be taken to a site to non-destructively obtain the moisture content. NMR technology is now being developed for this specific application in the form of a permanent magnet based probe and an associated backpack containing the necessary signal processing, control electronics and batteries

  7. Isotope labeling for NMR studies of macromolecular structure and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Wright, P.E. [Scripps Research Institute, La Jolla, CA (United States)

    1994-12-01

    Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform {sup 13}C, {sup 15}N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific {sup 13}C and {sup 15}N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions.

  8. A primer to nutritional metabolomics by NMR spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Savorani, Francesco; Rasmussen, Morten Arendt

    2013-01-01

    This paper outlines the advantages and disadvantages of using high throughput NMR metabolomics for nutritional studies with emphasis on the workflow and data analytical methods for generation of new knowledge. The paper describes one-by-one the major research activities in the interdisciplinary metabolomics platform and highlights the opportunities that NMR spectra can provide in future nutrition studies. Three areas are emphasized: (1) NMR as an unbiased and non-destructive platform for providing an overview of the metabolome under investigation, (2) NMR for providing versatile information and data structures for multivariate pattern recognition methods and (3) NMR for providing a unique fingerprint of the lipoprotein status of the subject. For the first time in history, by combining NMR spectroscopy and chemometrics we are able to perform inductive nutritional research as a complement to the deductive approach. (C) 2013 Elsevier Ltd. All rights reserved.

  9. High resolution solid state NMR techniques and applications in advanced materials

    International Nuclear Information System (INIS)

    Full text: High resolution solid state NMR has emerged as an important method for the structural characterization of diverse insoluble materials. A number of new techniques have been developed over the years for providing incisive characterization at the atomic level. We will introduce some of the newly developed magic angle spinning multi-pulse methods as applied to spin 1/2 (1H, 13C, 15N, 29Si, 31P) and half-integer (17O, 23Na, 25Mg, 27Al, 51V) nuclei, along with experimental schemes which provide enhanced sensitivity for studying low concentration of active species. Several applications of the methods to diverse materials, namely, microporous and mesoporous catalysis, hybrid materials, polymers, pharmaceutical polymorphs, nano-scale materials and energy storage materials will be presented. Additionally, spectral analysis and computer simulation methods will be introduced and their effective use for the quantitative determination of structurally relevant NMR parameters will be outlined

  10. 27Al and 29Si MAS NMR investigations of cordierite glass, mu- and alpha-cordierite.

    Science.gov (United States)

    Storek, W; Müller, R; Kunath-Fandrei, G

    1997-12-01

    27Al and 29Si Magic-Angle Spinning NMR results are reported for conventionally prepared glass of cordierite stoichiometry (2MgO.2Al2O3.5SiO2), the metastable high-quartz solid solution (mu-cordierite) and the high-temperature polymorph of cordierite (alpha-cordierite). Both, 27Al two-dimensional (2D) quadrupole nutation experiments and 27Al satellite transition spectroscopy (SATRAS) have been applied to identify two different tetrahedrally-coordinated aluminium sites (AlO4). SATRAS has been used to extract the quadrupole interaction parameters and their distribution, the isotropic chemical shifts and the relative populations of the different Al sites. Both, the 27Al and 29Si NMR results, lead to the conclusion that a perfect Si/Al disorder does not exist in these investigated cordierite samples. PMID:9477452

  11. Characterization of noninnocent metal complexes using solid-state NMR spectroscopy: o-dioxolene vanadium complexes.

    Science.gov (United States)

    Chatterjee, Pabitra B; Goncharov-Zapata, Olga; Quinn, Laurence L; Hou, Guangjin; Hamaed, Hiyam; Schurko, Robert W; Polenova, Tatyana; Crans, Debbie C

    2011-10-17

    (51)V solid-state NMR (SSNMR) studies of a series of noninnocent vanadium(V) catechol complexes have been conducted to evaluate the possibility that (51)V NMR observables, quadrupolar and chemical shift anisotropies, and electronic structures of such compounds can be used to characterize these compounds. The vanadium(V) catechol complexes described in these studies have relatively small quadrupolar coupling constants, which cover a surprisingly small range from 3.4 to 4.2 MHz. On the other hand, isotropic (51)V NMR chemical shifts cover a wide range from -200 to 400 ppm in solution and from -219 to 530 ppm in the solid state. A linear correlation of (51)V NMR isotropic solution and solid-state chemical shifts of complexes containing noninnocent ligands is observed. These experimental results provide the information needed for the application of (51)V SSNMR spectroscopy in characterizing the electronic properties of a wide variety of vanadium-containing systems and, in particular, those containing noninnocent ligands and that have chemical shifts outside the populated range of -300 to -700 ppm. The studies presented in this report demonstrate that the small quadrupolar couplings covering a narrow range of values reflect the symmetric electronic charge distribution, which is also similar across these complexes. These quadrupolar interaction parameters alone are not sufficient to capture the rich electronic structure of these complexes. In contrast, the chemical shift anisotropy tensor elements accessible from (51)V SSNMR experiments are a highly sensitive probe of subtle differences in electronic distribution and orbital occupancy in these compounds. Quantum chemical (density functional theory) calculations of NMR parameters for [VO(hshed)(Cat)] yield a (51)V chemical shift anisotropy tensor in reasonable agreement with the experimental results, but surprisingly the calculated quadrupolar coupling constant is significantly greater than the experimental value. The studies demonstrate that substitution of the catechol ligand with electron-donating groups results in an increase in the HOMO-LUMO gap and can be directly followed by an upfield shift for the vanadium catechol complex. In contrast, substitution of the catechol ligand with electron-withdrawing groups results in a decrease in the HOMO-LUMO gap and can directly be followed by a downfield shift for the complex. The vanadium catechol complexes were used in this work because (51)V is a half-integer quadrupolar nucleus whose NMR observables are highly sensitive to the local environment. However, the results are general and could be extended to other redox-active complexes that exhibit coordination chemistry similar to that of the vanadium catechol complexes. PMID:21842875

  12. Nucleic acid helix structure determination from NMR proton chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Werf, Ramon M. van der; Tessari, Marco; Wijmenga, Sybren S., E-mail: S.Wijmenga@science.ru.nl [Radboud University Nijmegen, Department of Biophysical Chemistry, Institute of Molecules and Materials (Netherlands)

    2013-06-15

    We present a method for de novo derivation of the three-dimensional helix structure of nucleic acids using non-exchangeable proton chemical shifts as sole source of experimental restraints. The method is called chemical shift de novo structure derivation protocol employing singular value decomposition (CHEOPS) and uses iterative singular value decomposition to optimize the structure in helix parameter space. The correct performance of CHEOPS and its range of application are established via an extensive set of structure derivations using either simulated or experimental chemical shifts as input. The simulated input data are used to assess in a defined manner the effect of errors or limitations in the input data on the derived structures. We find that the RNA helix parameters can be determined with high accuracy. We finally demonstrate via three deposited RNA structures that experimental proton chemical shifts suffice to derive RNA helix structures with high precision and accuracy. CHEOPS provides, subject to further development, new directions for high-resolution NMR structure determination of nucleic acids.

  13. Solvent exchange on metal ions: a variable pressure NMR approach

    International Nuclear Information System (INIS)

    Among the possible fields of application to solution chemistry, ionic solvation is studied using an unusual approach, DNMR under high pressure: high pressure NMR instrumentation and methodology, NMR techniques for the study of solvent exchange (isotopic labelling, line-shape analysis, relaxation rate measurements, magnetization transfer, 2-D NMR); studies in the fields of octahedral complexes, tetrahedral complexes, lanthanide ions, square planar complexes, are discussed. 19 fig., 12 tab., 95 ref

  14. Fluid-Rock Characterization and Interactions in NMR Well Logging

    Energy Technology Data Exchange (ETDEWEB)

    Hirasaki, George J.; Mohanty, Kishore K.

    2003-02-10

    The objective of this project was to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. The advances made in the understanding of NMR fluid properties are summarized in a chapter written for an AAPG book on NMR well logging. This includes live oils, viscous oils, natural gas mixtures, and the relation between relaxation time and diffusivity.

  15. Overhauser Dynamic Nuclear Polarization-Enhanced NMR Relaxometry

    OpenAIRE

    Franck, John M.; Kausik, Ravinath; Han, Songi

    2013-01-01

    We present a new methodological basis for selectively illuminating a dilute population of fluid within a porous medium. Specifically, transport in porous materials can be analyzed by now-standard nuclear magnetic resonance (NMR) relaxometry and NMR pulsed field gradient (PFG) diffusometry methods in combination with with the prominent NMR signal amplification tool, dynamic nuclear polarization (DNP). The key components of the approach introduced here are (1) to selectively place intrinsic or ...

  16. Rotational Doppler Effect and Barnett Field in Spinning NMR

    Science.gov (United States)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  17. Review of advances in coupling electrochemistry and liquid state NMR.

    Science.gov (United States)

    Bussy, Ugo; Boujtita, Mohammed

    2015-05-01

    The coupling of electrochemistry and NMR spectroscopy (EC-NMR) may present an interesting approach in the environmental oxidative degradation or metabolism studies. This review presents experimental advances in the field of EC-NMR and highlights the main advantages and drawbacks of in situ and on line of NMR spectroelectrochemistry. The analysis of NMR spectra recorded in situ or on line EC-NMR permits to elucidate the reaction pathway of the electrochemical oxidation reactions and could constitute a fast way for monitoring unstable species as for instance quinone and quinone imine structures without using any coupling agents. The use of 1D and 2D NMR coupled with electrochemistry may leads to the elucidation of the major species produced from the electrochemical oxidation process. The present review gives an overview about the development of the electrochemical cells which can operate on line or in situ with NMR measurements. Future developments and potential applications of EC-NMR are also discussed. PMID:25702997

  18. Understanding NMR relaxometry of partially water-saturated rocks

    Science.gov (United States)

    Mohnke, O.; Jorand, R.; Nordlund, C.; Klitzsch, N.

    2015-06-01

    Nuclear magnetic resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. Estimations of these properties are based on the direct link of the initial NMR signal amplitude to porosity (water content) and of the NMR relaxation time to pore size. Herein, pore shapes are usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks may differ strongly from the responses calculated for spherical or cylindrical pores, because these pore shapes do not account for water menisci remaining in the corners of desaturated angular pores. Therefore, we consider a bundle of pores with triangular cross sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of desaturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions. For this pore model, the NMR amplitudes and NMR relaxation times at partial water saturation strongly depend on pore shape, i.e., arising from the capillary pressure and pore shape-dependent water distribution in desaturated pores with triangular cross sections. Even so, the NMR relaxation time at full saturation only depends on the surface-to-volume ratio of the pore. Moreover, we show the qualitative agreement of the saturation-dependent relaxation-time distributions of our model with those observed for rocks and soils.

  19. Combination of NMR relaxometry and mechanical testing during vulcanization

    OpenAIRE

    Kahle, S.; Nussbaum, W.; Hehn, M.; Raich, H. P.; Wilhelm, M.; Blümler, P.

    2008-01-01

    A new design for an in-situ combination of NMR and rheological measurements is presented. The NMR instrumentation is based on a Bruker Minispec spectrometer with a home-built magnet system consisting of 64 permanent magnets in a so-called MANDHALA arrangement. This magnet reaches a flux density of about 0.23T, corresponding to a 1H NMR resonance frequency of about 9.5MHz. The NMR apparatus is combined with a Scarabaeus SISV50 instrument with modified sample cells to allow synchronous in...

  20. Physiological parameters

    International Nuclear Information System (INIS)

    The physiological characteristics of man depend on the intake, metabolism and excretion of stable elements from food, water, and air. The physiological behavior of natural radionuclides and radionuclides from nuclear weapons testing and from the utilization of nuclear energy is believed to follow the pattern of stable elements. Hence information on the normal physiological processes occurring in the human body plays an important role in the assessment of the radiation dose received by man. Two important physiological parameters needed for internal dose determination are the pulmonary function and the water balance. In the Coordinated Research Programme on the characterization of Asian population, five participants submitted data on these physiological characteristics - China, India, Japan, Philippines and Viet Nam. During the CRP, data on other pertinent characteristics such as physical and dietary were simultaneously being collected. Hence, the information on the physiological characteristics alone, coming from the five participants were not complete and are probably not sufficient to establish standard values for the Reference Asian Man. Nonetheless, the data collected is a valuable contribution to this research programme

  1. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoaceticum metabolic profiles

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Junfeng; Isern, Nancy G.; Ewing, R James; Liyu, Andrey V.; Sears, Jesse A.; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R.; Ahring, Birgitte K.; Majors, Paul D.

    2014-06-20

    An in-situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch-growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution, high sensitivity NMR (HR-NMR) spectroscopy. In-situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at an NMR frequency of 500 MHz, and aliquots of the bioreactor contents were taken for 600 MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in-situ NMR bioreactor facilitated monitoring of the fermentation process in real time, enabling identification of intermediate and end-point metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with the HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.

  2. Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

    Science.gov (United States)

    Mao, Jingdong; Fang, Xiaowen; Lan, Yeqing; Schimmelmann, Arndt; Mastalerz, Maria; Xu, Ling; Schmidt-Rohr, Klaus

    2010-04-01

    We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH 3, CH 2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (˜30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ˜30 carbons, and of ˜20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H- 13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters.

  3. Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

    Science.gov (United States)

    Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

    2010-01-01

    We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

  4. Lithium Polymer Electrolytes and Solid State NMR

    Science.gov (United States)

    Berkeley, Emily R.

    2004-01-01

    Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for participation on a variety of other projects, including aero-gels and carbon graphite mat en als. The goals of the polymer electrolyte research are to improve the physical properties of the polymers. This includes improving conductivity, durability, and expanding the temperature range over which it is effective. Currently, good conductivity is only present at high temperatures. My goals are to experiment with different arrangements of rods and coils to achieve these desirable properties. Some of my experiments include changing the number of repeat units in the polymer, the size of the diamines, and the types of coil. Analysis of these new polymers indicates improvement in some properties, such as lower glass transition temperature; however, they are not as flexible as desired. With further research we hope to produce polymers that encompass all of these properties to a high degree.

  5. Elastic deformation and area per lipid of membranes: atomistic view from solid-state deuterium NMR spectroscopy.

    Science.gov (United States)

    Kinnun, Jacob J; Mallikarjunaiah, K J; Petrache, Horia I; Brown, Michael F

    2015-01-01

    This article reviews the application of solid-state ²H nuclear magnetic resonance (NMR) spectroscopy for investigating the deformation of lipid bilayers at the atomistic level. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Solid-state ²H NMR yields observables directly related to the stress field of the lipid bilayer. The extent to which lipid bilayers are deformed by osmotic pressure is integral to how lipid-protein interactions affect membrane functions. Calculations of the average area per lipid and related structural properties are pertinent to bilayer remodeling and molecular dynamics (MD) simulations of membranes. To establish structural quantities, such as area per lipid and volumetric bilayer thickness, a mean-torque analysis of ²H NMR order parameters is applied. Osmotic stress is introduced by adding polymer solutions or by gravimetric dehydration, which are thermodynamically equivalent. Solid-state NMR studies of lipids under osmotic stress probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions. Removal of water yields a reduction of the mean area per lipid, with a corresponding increase in volumetric bilayer thickness, by up to 20% in the liquid-crystalline state. Hydrophobic mismatch can shift protein states involving mechanosensation, transport, and molecular recognition by G-protein-coupled receptors. Measurements of the order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Solid-state ²H NMR thus reveals how membrane deformation can affect protein conformational changes within the stress field of the lipid bilayer. PMID:24946141

  6. Detailed Analysis of Phenylsilane Polymers by 29Si NMR Supported by GPC-NMR.

    Czech Academy of Sciences Publication Activity Database

    Pinkas, Ji?í; Merna, J.; Karban, Jind?ich; Sýkora, Jan

    Dead Sea : University of Jordan, 2010. s. 132. [Eurasia Conference on Chemical Sciences /11./. 06.10.2010-10.10.2010, Dead Sea] Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40720504 Keywords : phenylsilane polymers * NMR * catalysis Subject RIV: CF - Physical ; Theoretical Chemistry

  7. Touch NMR: An NMR Data Processing Application for the iPad

    Science.gov (United States)

    Li, Qiyue; Chen, Zhiwei; Yan, Zhiping; Wang, Cheng; Chen, Zhong

    2014-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has become one of the most powerful technologies to aid research in numerous scientific disciplines. With the development of consumer electronics, mobile devices have played increasingly important roles in our daily life. However, there is currently no application available for mobile devices able to…

  8. Characterization by NMR of Ozonized methyl linoleate

    Scientific Electronic Library Online (English)

    Maritza F., Díaz; José A., Gavín.

    Full Text Available No presente estudo o linoleato de metila ozonizado com índice de peróxidos de 1.800 mmol-equiv. kg-1 foi caracterizado quimicamente. Os efeitos do ozônio sobre o linoleato de metila produz hidroperóxidos, ozonideos e aldeídos, os quais foram identificados por técnicas de ressonância magnética nuclea [...] r de ¹H e 13C, mono- e bidimensional. O linoleato de metila padrão e o linoleato de metila ozonizado mostram espectros muito similares, excetuando os valores de ressonância (delta 9,7 e delta 9,6) que correspondem aos hidrogênios aldeídicos (delta 5,7 e delta 5,5) e olefínicos de hidroperóxidos (delta 5,2). Outras atribuições estão baseadas nas conectividades fornecidas pelas constantes de acoplamento. Estes resultados indicam que a espectrometria de RMN pode oferecer informação valiosa a respeito da quantidade de compostos oxigenados formados à partir do linoleato de metila ozonizado para o uso em ozonoterapia e na química de óleos vegetais ozonizados. Abstract in english In the present study ozonized methyl linoleate with peroxide index of 1,800 mmol-equiv kg-1 was chemically characterized. Ozonation of methyl linoleate produced hydroperoxides, ozonides and aldehydes which were identified by ¹H and 13C NMR two-dimensional. The standard methyl linoleate and ozonized [...] methyl linoleate shown very similar ¹H NMR spectra except for the signals at delta 9.7 and delta 9.6 that correspond to aldehydic hydrogen, delta 5.7 and delta 5.5 (olefinic signals from hydroperoxides) and delta 5.2 ppm (multiplet from ozonides methynic hydrogen). Other resonance assignments are based on the connectivities provided by the hydrogen scalar coupling constants. These results indicate that NMR spectroscopy can provide valuable information about the amount of formed oxygenated compounds in the ozonized methyl linoleate in order to use it to follow up ozone therapy and chemistry of ozonized vegetable oil.

  9. CHARACTERIZATION OF METABOLITES IN SMALL FISH BIOFLUIDS AND TISSUES BY NMR SPECTROSCOPY

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized for assessing ecotoxicity in small fish models by means of metabolomics. Two fundamental challenges of NMR-based metabolomics are the detection limit and characterization of metabolites (or NMR resonance assignments...

  10. Safety assessment of NMR clinical equipment

    International Nuclear Information System (INIS)

    This are the proceedings of a workshop held on March 13/14, 1986, in Tuebingen, FRG, within the activities of the EEC Concerted Research Project 'Identification and Characterization of Biological Tissues by NMR', carried out under the auspices of the Biomedical Engineering Group, EEC Committee on Medical and Public Health. The 17 lectures are presented as full-text papers or as compacts. Beside of safety aspects the main themes are the biological effects of magnetic fields and electric currents on body temperature, blood flow, brain, etc. (orig./MG)

  11. In Vivo Measurements of NMR Relaxation Times

    OpenAIRE

    Kroeker, Randall M.; Mcveigh, Elliot R.; Hardy, Peter; Bronskill, Michael J.; Henkelman, R Mark

    1985-01-01

    A series of solenoidal NMR probes were built to measure T1 and T2 relaxation times in vivo in the mouse, over the frequency range of 5 to 60 MHz, using inversion-recovery and spin-echo pulse sequences. KHT tumors growing in the legs of C3H mice were studied and compared with normal mouse legs. The tumor relaxation times were studied at 10 MHz during the course of tumor growth and as a function of frequency when the tumor had a mass of approximately 0.9 g. Mouse legs with tumors have higher T1...

  12. High resolution NMR theory and chemical applications

    CERN Document Server

    Becker, Edwin D

    1980-01-01

    High Resolution NMR: Theory and Chemical Applications discusses the principles and theory of nuclear magnetic resonance and how this concept is used in the chemical sciences. This book is written at an intermediate level, with mathematics used to augment verbal descriptions of the phenomena. This text pays attention to developing and interrelating four approaches - the steady state energy levels, the rotating vector picture, the density matrix, and the product operator formalism. The style of this book is based on the assumption that the reader has an acquaintance with the general principles o

  13. Structural study of pyrones by NMR

    International Nuclear Information System (INIS)

    Extracts of two species of Aniba, designed Aniba-SA (light petroleum extract) and Aniba-SB (benzene extract), afforded by chromatographic fraccionation some compounds. The isolated compounds were identified using spectrometric data and C13-NMR coupled and decompled spectra of pyrones were registered. Measurement of the heteronuclear residual coupling by irradiation proton frequency off-resonance was used for distinguish C-5, C-7 and C-8 carbons of the pyrones SB-1, SB-3, SB-4 and SB-5. (M.J.C.)

  14. Temperature dependence of NMR in magnetite.

    Czech Academy of Sciences Publication Activity Database

    Novák, Pavel; Št?pánková, H.; Englich, J.; Kohout, J.; Brabers, V. A. M.

    Kyoto : The Japan Society of Powder and Powder Metallurgy, 2000 - (Abe, M.; Yamazaki, Y.), s. 131-134 ISBN 4-9900214-7-9. [International Conference on Ferrites /8./. Kyoto (JP), 18.09.2000-21.09.2000] R&D Projects: GA ?R GA202/00/1601; GA ?R GA202/97/P070 Grant ostatní: GA UK(XC) 170/2000/B-FYZ Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetite * NMR Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. A NMR spectrometer for educational purposes

    International Nuclear Information System (INIS)

    A NMR spectrometer has been constructed for educational purposes, such as teaching of the technique basic principles and instrumentation. The spectrometer has been designed with a minimum number of components so that the students may have acquittance with both the spectrometer, through block diagrams, and the small numbers of existent components . The device was based on a 0.t Tesla magnet from the continuous wave spectrometer (E M 300 - Varian) existent at the Instituto Militar de Engenharia, and it is expected to facilitate the comprehension of the commercial spectrometers

  16. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.

    Science.gov (United States)

    Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D

    2014-10-01

    An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts. PMID:24946863

  17. DC SQUID-based NMR detection from room temperature samples

    International Nuclear Information System (INIS)

    The authors have recently succeeded in measuring an NMR signal at 0.01 T from a sample at room temperature using a receiver based on the DC superconducting quantum interference device (SQUID). It is believed that this is the first time that a SQUID has been used for a direct NMR measurement from a sample positioned outside the cryogenic environment. (author)

  18. What can Lattice QCD theorists learn from NMR spectroscopists?

    CERN Document Server

    Fleming, George T

    2004-01-01

    Euclidean-time hadron correlation functions computed in Lattice QCD (LQCD) are modeled by a sum of decaying exponentials, reminiscent of the exponentially damped sinusoid models of free induction decay (FID) in Nuclear Magnetic Resonance (NMR) spectroscopy. We present our initial progress in studying how data modeling techniques commonly used in NMR perform when applied to LQCD data.

  19. Development of portable NMR polarimeter system for polarized HD target

    International Nuclear Information System (INIS)

    A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.

  20. Development of portable NMR polarimeter system for polarized HD target

    CERN Document Server

    Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

    2011-01-01

    A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 kg to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.

  1. What can Lattice QCD theorists learn from NMR spectroscopists?

    International Nuclear Information System (INIS)

    Euclidean-time hadron correlation functions computed in Lattice QCD (LQCD) are modeled by a sum of decaying exponentials, reminiscent of the exponentially damped sinusoid models of free induction decay (FID) in Nuclear Magnetic Resonance (NMR) spectroscopy. We present our initial progress in studying how data modeling techniques commonly used in NMR perform when applied to LQCD data

  2. NMR crystallography of active pharmaceuticals ingredients for industrial applications.

    Czech Academy of Sciences Publication Activity Database

    Urbanová, Martina; Brus, Ji?í; Kobera, Libor

    Herceg Novi : Materials Research Society, 2008. s. 165. [Annual Conference YUCOMAT 2008 /10./. 08.09.2008-12.09.2008, Herceg Novi] R&D Projects: GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : MAS NMR * atorvastatin * NMR crystallography Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Variations of NMR signals by hyperpolarization and ultrasound

    International Nuclear Information System (INIS)

    In this thesis it is described how p-NMR can be applied to metals with verlo low hydrogen concentrations and how a combination of ultrasound and NMR can lead to an improvement of the measureing method. As examples measurements on H2O and ethanol are described. (HSI)

  4. NMR CHARACTERIZATION OF DIHYDROSTERCULIC ACID AND ITS METHYL ESTER

    Science.gov (United States)

    Dihydrosterculic acid (2-octyl cyclopropaneoctanoic acid) and its methyl ester were selected for 1H- and 13C-NMR analysis as compounds representative of cyclopropane fatty acids. The 500 MHz 1H-NMR spectra acquired with CDCl3 as solvent show two individual peaks at -0.30 and 0.60 ppm for the methyl...

  5. Two-dimensional NMR spectroscopy. Applications for chemists and biochemists

    International Nuclear Information System (INIS)

    Two-dimensional nuclear magnetic resonance spectroscopy (2-D NMR) has become a very powerful class of experiments (in the hands of an adept scientist) with broad adaptability to new situations. It is the product of a happy marriage between modern pulse FT-NMR technology, with its large memory and high-speed computers, and the physicists and chemists who love to manipulate spin systems. Basic 2-D experiments are now a standard capability of modern NMR spectrometers, and this timely book intends to make 2-D NMR users of those who are familiar with normal 1-D NMR. The 2-D NMR goal is correlation of the lines of the observed NMR spectrum with other properties of the system. This book deals with applications to high-resolution spectrum analysis, utilizing either coupling between the NMR-active nuclei or chemical exchange to perform the correlation. The coupling can be scalar (through bonds) or direct through space (within 5 A). The coupling may be homonuclear (between like nuclei) or heteronuclear

  6. Web Spectra: Problems in NMR and IR spectroscopy

    Science.gov (United States)

    Merlic, Craig A.

    This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13 C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy.

  7. NMR structure validation in relation to dynamics and structure determination.

    Science.gov (United States)

    Vranken, Wim F

    2014-10-01

    NMR spectroscopy is a key technique for understanding the behaviour of proteins, especially highly dynamic proteins that adopt multiple conformations in solution. Overall, protein structures determined from NMR spectroscopy data constitute just over 10% of the Protein Data Bank archive. This review covers the validation of these NMR protein structures, but rather than describing currently available methodology, it focuses on concepts that are important for understanding where and how validation is most relevant. First, the inherent characteristics of the protein under study have an influence on quality and quantity of the distinct types of data that can be acquired from NMR experiments. Second, these NMR data are necessarily transformed into a model for use in a structure calculation protocol, and the protein structures that result from this reflect the types of NMR data used as well as the protein characteristics. The validation of NMR protein structures should therefore take account, wherever possible, of the inherent behavioural characteristics of the protein, the types of available NMR data, and the calculation protocol. These concepts are discussed in the context of 'knowledge based' and 'model versus data' validation, with suggestions for questions to ask and different validation categories to consider. The principal aim of this review is to stimulate discussion and to help the reader understand the relationships between the above elements in order to make informed decisions on which validation approaches are the most relevant in particular cases. PMID:25444697

  8. Exploring abiotic stress on asynchronous protein metabolism in single kernels of wheat studied by NMR spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Winning, H; Viereck, N

    2009-01-01

    Extreme climate events are being recognized as important factors in the effects on crop growth and yield. Increased climatic variability leads to more frequent extreme conditions which may result in crops being exposed to more than one extreme event within a growing season. The aim of this study was to examine the implications of different drought treatments on the protein fractions in grains of winter wheat using 1H nuclear magnetic resonance spectroscopy followed by chemometric analysis. Triticum aestivum L. cv. Vinjett was studied in a semi-field experiment and subjected to drought episodes either at terminal spikelet, during grain-filling or at both stages. Principal component trajectories of the total protein content and the protein fractions of flour as well as the 1H NMR spectra of single wheat kernels, wheat flour, and wheat methanol extracts were analysed to elucidate the metabolic development during grain-filling. The results from both the 1H NMR spectra of methanol extracts and the 1H HR-MAS NMR ofsingle kernels showed that a single drought event during the generative stage had as strong an influence on protein metabolism as two consecutive events of drought. By contrast, a drought event at the vegetative growth stage had little effect on the parameters investigated. For the first time, 1H HR-MAS NMR spectra of grains taken during grain-filling were analysed by an advanced multiway model. In addition to the results from the chemical protein analysis and the 1H HR-MAS NMR spectra of single kernels indicating that protein metabolism is influenced by multiple drought events, the 1H NMR spectra of the methanol extracts of flour from mature grains revealed that the amount of fumaric acid is particularly sensitive to water deficits.

  9. Exploring abiotic stress on asynchronous protein metabolism in single kernels of wheat studied by NMR spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Winning, H.; Viereck, N.

    2009-01-01

    Extreme climate events are being recognized as important factors in the effects on crop growth and yield. Increased climatic variability leads to more frequent extreme conditions which may result in crops being exposed to more than one extreme event within a growing season. The aim of this study was to examine the implications of different drought treatments on the protein fractions in grains of winter wheat using H-1 nuclear magnetic resonance spectroscopy followed by chemometric analysis. Triticum aestivum L. cv. Vinjett was studied in a semi-field experiment and subjected to drought episodes either at terminal spikelet, during grain-filling or at both stages. Principal component trajectories of the total protein content and the protein fractions of flour as well as the H-1 NMR spectra of single wheat kernels, wheat flour, and wheat methanol extracts were analysed to elucidate the metabolic development during grain-filling. The results from both the H-1 NMR spectra of methanol extracts and the H-1 HR-MAS NMR of single kernels showed that a single drought event during the generative stage had as strong an influence on protein metabolism as two consecutive events of drought. By contrast, a drought event at the vegetative growth stage had little effect on the parameters investigated. For the first time, H-1 HR-MAS NMR spectra of grains taken during grain-filling were analysed by an advanced multiway model. In addition to the results from the chemical protein analysis and the H-1 HR-MAS NMR spectra of single kernels indicating that protein metabolism is influenced by multiple drought events, the H-1 NMR spectra of the methanol extracts of flour from mature grains revealed that the amount of fumaric acid is particularly sensitive to water deficits.

  10. Experimental and NMR theoretical methodology applied to geometric analysis of the bioactive clerodane trans-dehydrocrotonin

    Scientific Electronic Library Online (English)

    Breno Almeida, Soares; Caio Lima, Firme; Maria Aparecida Medeiros, Maciel; Carlos R., Kaiser; Eduardo, Schilling; Adailton J., Bortoluzzi.

    2014-04-01

    Full Text Available trans-Desidrocrotonina (t-DCTN), um bioditerpeno do tipo 19-nor-clerodano isolado de Croton cajucara Benth, representa um dos clerodanos da atualidade com maiores índices de investigações científicas. Neste trabalho, uma nova abordagem unindo dados de difração de raios X, dados de ressonância magnét [...] ica nuclear (NMR) e dados teóricos foi aplicada para a completa caracterização da t-DCTN. Para tanto, a geometria de t-DCTN foi reavaliada por difração de raios X e NMR de ¹H e 13C e foi comparada com os dados teóricos obtidos por B3LYP/6-311G++(d,p). A subsequente avaliação dos valores teóricos e experimentais de deslocamentos químicos de NMR e constantes de acoplamento spin-spin apresentou correlações muito boas entre propriedades magnéticas teóricas e experimentais. Adicionalmente, os índices de deslocalização entre átomos de hidrogênio, d(H,H'), correlacionaram bem com os dados experimentais e calculados de constante de acoplamento. Uma análise topológica complementar utilizando a teoria quântica de átomos em moléculas (QTAIM) mostrou interações intramoleculares para t-DCTN. Abstract in english trans-Dehydrocrotonin (t-DCTN) a bioactive 19-nor-diterpenoid clerodane type isolated from Croton cajucara Benth, is one of the most investigated clerodane in the current literature. In this work, a new approach joining X-ray diffraction data, nuclear magnetic resonance (NMR) data and theoretical ca [...] lculations was applied to the thorough characterization of t-DCTN. For that, the geometry of t-DCTN was reevaluated by X-ray diffraction as well as ¹H and 13C NMR data, whose geometrical parameters where compared to those obtained from B3LYP/6-311G++(d,p) level of theory. From the evaluation of both calculated and experimental values of ¹H and 13C NMR chemical shifts and spin-spin coupling constants, it was found very good correlations between theoretical and experimental magnetic properties of t-DCTN. Additionally, the delocalization indexes between hydrogen atoms correlated accurately with theoretical and experimental spin-spin coupling constants. An additional topological analysis from quantum theory of atoms in molecules (QTAIM) showed intramolecular interactions for t-DCTN.

  11. NMR studies of actinide oxides - A review

    Science.gov (United States)

    Walstedt, Russell E.; Tokunaga, Yo; Kambe, Shinsaku

    2014-08-01

    In this paper, we offer a brief review of the ground-state properties of the cubic oxides AnO2, where An=U, Np, Pu and Am, as revealed mainly by NMR studies of the 17O2- ligand. For PuO2, where the ground state is a nonmagnetic singlet eigenstate of the cubic crystal field, only the 239Pu has been studied, in a recent breakthrough observation of this elusive isotope [1]. For UO2 and NpO2, the former has an exotic four-sublattice antiferromagnetic (AFM) ground state, while the latter has the first multipolar ground state to be identified among actinide compounds, namely a mixture of octupolar and rank 5 (triakontadipolar) order. On the other hand AmO2, even with the longest-lived isotope 243Am, becomes disordered so quickly from radiation self-damage that its ground state in a recent study was simply a spin glass, while the actual ground state of the cubic crystalline compound remains obscured by this experimental problem. The emphasis throughout is on how 17O NMR studies complement other experimental data to confirm and verify the known exotic magnetic ground states of AnO2 systems. xml:lang="fr"

  12. NMR study of high-TC superconductors

    International Nuclear Information System (INIS)

    Recent NMR study of high-TC superconductors carried out by Osaka group is reviewed. NQR frequency ?Q, Knight shift K, T1 of 63Cu and 17O were measured over a wide hole doping range from light- to heavy-doped systems, LSCO, YBCO, HBCCO, BSCCO, TBCCO and TBCO, together with impurity and pressure effect. By analysing ?Q, K and T1, the local hole numbers of Cu and O at the CuO2 plane, n(Cu) and n(O) the relative magnitude of the uniform susceptibility, ?0 and the low-frequency component of the antiferromagnetic spin fluctuations (AFSF), ?Q/? (?Q is the staggered susceptibility and ? is the characteristic energy of the spin fluctuation at q=0) are obtained. The relation between n(Cu), n(O) and ?Q, ?Q/?, TC, etc. were discussed. There are optimum values of n(Cu)/2n(O) and n(Cu)+2n(O) to give maximum TC. The NMR results in the superconducting state are well-explained by d-wave pairing model. The result is consistent with the AFSF mediated superconducting model. (orig.)

  13. In vivo NMR spectroscopy of ripening avocado

    International Nuclear Information System (INIS)

    Ripening of avocado fruit is associated with a dramatic increase in respiration. Previous studies have indicated that the increase in respiration is brought about by activation of the glycolytic reaction catalyzing the conversion of fructose-6-phosphate to fructose 1,6-bisphosphate. The authors reinvestigated the proposed role of glycolytic regulation in the respiratory increase using in vivo 31P nuclear magnetic resonance (NMR) spectroscopy using an external surface coil and analysis of phosphofructokinase (PFK), phosphofructophosphotransferase (PFP), and fructose 2,6-bisphosphate (fru 2,6-P2) levels in ripening avocado fruit. In vivo 31P NMR spectroscopy revealed large increases in ATP levels accompanying the increase in respiration. Both glycolytic enzymes, PFK and PFP, were present in avocado fruit, with the latter activity being highly stimulated by fru 2,6-P2. Fructose 2,6-bisphosphate levels increased approximately 90% at the onset of ripening, indicating that the respiratory increase in ripening avocado may be regulated by the activation of PFP brought about by an increase in fru 2,6-P2

  14. Use of earth field spin echo NMR to search for liquid minerals

    Science.gov (United States)

    Stoeffl, Wolfgang (Livermore, CA)

    2001-01-01

    An instrument for measuring the spatial, qualitative and quantitative parameters of an underground nuclear magnetic resonance (NMR) active liquid mineral deposit, including oil and water. A phased array of excitation and receiver antennas on the surface and/or in a borehole excites the NMR active nuclei in the deposit, and using known techniques from magnetic resonance imaging (MRI), the spatial and quantitative distribution of the deposit can be measured. A surface array may utilize, for example, four large (50-500 diameter) diameter wire loops laid on the ground surface, and a weak (1.5-2.5 kHz) alternating current (AC) field applied, matching the NMR frequency of hydrogen in the rather flat and uniform earth magnetic field. For a short duration (a few seconds) an additional gradient field can be generated, superimposed to the earth field, by applying direct current (DC) to the grid (wire loops), enhancing the position sensitivity of the spin-echo and also suppressing large surface water signals by shifting them to a different frequency. The surface coil excitation can be combined with downhole receivers, which are much more radio-quiet compared to surface receivers, and this combination also enhances the position resolution of the MRI significantly. A downhole receiver module, for example, may have a 5.5 inch diameter and fit in a standard six inch borehole having a one-quarter inch thick stainless steel casing. The receiver module may include more than one receiver units for improved penetration and better position resolution.

  15. In vivo quantitative NMR imaging of fruit tissues during growth using Spoiled Gradient Echo sequence.

    Science.gov (United States)

    Kenouche, S; Perrier, M; Bertin, N; Larionova, J; Ayadi, A; Zanca, M; Long, J; Bezzi, N; Stein, P C; Guari, Y; Cieslak, M; Godin, C; Goze-Bac, C

    2014-12-01

    Nondestructive studies of physiological processes in agronomic products require increasingly higher spatial and temporal resolutions. Nuclear Magnetic Resonance (NMR) imaging is a non-invasive technique providing physiological and morphological information on biological tissues. The aim of this study was to design a robust and accurate quantitative measurement method based on NMR imaging combined with contrast agent (CA) for mapping and quantifying water transport in growing cherry tomato fruits. A multiple flip-angle Spoiled Gradient Echo (SGE) imaging sequence was used to evaluate the intrinsic parameters maps M0 and T1 of the fruit tissues. Water transport and paths flow were monitored using Gd(3+)/[Fe(CN)6](3-)/D-mannitol nanoparticles as a tracer. This dynamic study was carried out using a compartmental modeling. The CA was preferentially accumulated in the surrounding tissues of columella and in the seed envelopes. The total quantities and the average volume flow of water estimated are: 198 mg, 1.76 mm(3)/h for the columella and 326 mg, 2.91 mm(3)/h for the seed envelopes. We demonstrate in this paper that the NMR imaging technique coupled with efficient and biocompatible CA in physiological medium has the potential to become a major tool in plant physiology research. PMID:25131625

  16. In situ NMR observation of mono- and binuclear rhodium dihydride complexes using parahydrogen-induced polarization.

    Science.gov (United States)

    Koch, A; Bargon, J

    2001-01-29

    Starting from the binuclear complex [RhCl(NBD)]2 (NBD = 2,5-norbornadiene) in the presence of the phosphines L = PMe3, PMe2Ph, PMePh2, PEt3, PEt2Ph, PEtPh2, or P(n-butyl)3, various mononuclear dihydrides of the type Rh(H)2CIL3, i.e., those of the homogeneous hydrogenation catalysts RhCIL3, have been obtained upon addition of parahydrogen, and their 1H NMR spectra have been investigated using parahydrogen-induced polarization (PHIP). Furthermore, the two binuclear complexes (H)(Cl)Rh(PMe3)2(mu-Cl)(mu-H)Rh(PMe3) and (H)(Cl)Rh(PMe2Ph)2(mu-Cl)(mu-H)Rh(PMe2Ph) have been detected and characterized by means of this in situ NMR method. Analogous complexes with trifluoroacetate instead of chloride, i.e., Rh(H)2(CF3COO)L3, have been generated in situ starting from Rh(NBD)(acac) in the presence of trifluoroacetic acid in combination with the phosphines L = PPh3, PEt2Ph, PEt3, and P(n-butyl)3, and their 1H NMR parameters have been determined. PMID:11209612

  17. Theoretical and experimental IR, Raman and NMR spectra in studying the electronic structure of 2-nitrobenzoates

    Science.gov (United States)

    ?wis?ocka, R.; Samsonowicz, M.; Regulska, E.; Lewandowski, W.

    2007-05-01

    The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-nitrobenzoic acid (2-NBA) was studied. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6-311++G ?? basis set. The theoretical IR and NMR spectra were obtained. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-nitrobenzoic acid salts of alkali metals were also recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 2-nitrobenzoates (2-NB) and ionic potential, electronegativity, atomic mass and affinity of metals were found. The chemical shifts of protons and carbons ( 1H, 13C NMR) in the series of studied alkali metal 2-nitrobenzoates were observed too. The calculated parameters were compared to experimental characteristic of studied compounds.

  18. Powder MAS NMR lineshapes of quadrupolar nuclei in the presence of second-order quadrupole interaction.

    Science.gov (United States)

    Ajoy, G; Ramakrishna, J; Bahçeli, S; Klinowski, J

    2000-07-01

    We derive a complete analytical solution for the powder magic angle spinning (MAS) nuclear magnetic resonance (NMR) lineshape in the presence of second-order quadrupole interaction, considering a radiofrequency (rf) pulse of finite width, a finite MAS frequency, and a non-zero asymmetry parameter. (Ix) is calculated using two approaches. The first applies time-dependent perturbation theory in the presence of the rf pulse and stationary perturbation theory (SPT) in its absence. The second is based on the Magnus expansion of the density matrix in the interaction representation during the pulse and SPT in its absence. We solve the problem in the laboratory frame using the properties of the Fourier transform and spin operators. Diagonalisation is not required. Both approaches agree well with each other under all conditions and also with the transition probability approach for the central transition. The Magnus expansion exists at all times and the effect of the non-secular terms is negligible. We describe an analytical method of averaging (Ix) over the Euler angles and simulate the 11B MAS NMR lineshapes for crystalline and vitreous B2O3. A critical analysis is given of all earlier calculations of the MAS NMR lineshape. PMID:10928635

  19. Nuclear quadrupole perturbations in 51V NMR spectra of oxovanadium(+V) complexes

    International Nuclear Information System (INIS)

    Nuclear electric quadrupole coupling constants e2qQ/h have been obtained by evaluation of quadrupole perturbations in 51V NMR spectra of various vanadyl esters and esterchlorides of the general formula VOCCsub(3-n)(OR)sub(n) (n=0-3; R=Me, Prsup(n), Prsup(i), Busup(n) and Busup(i)). e2qQ/h values have been calculated from (i) 2nd. order quadrupole splitting of the 51V NMR signals in pseudopolycrystalline samples, (ii) 1st. order quadrupole splittings in nematic liquid crystals and (iii) line widths ?#betta#sub(1/2) of the 51V and 35CI NMR signals in the liquid isotropic state and e2qQ/h(35CI) obtained by pure NQR measurements. The influences of the asymmetry parameter eta and the orientation of the crystallites in powder spectra are considered, and temperature and concentration effects upon ?#betta#sub(1/2) and 51V shielding (isotropic phases) and the ordering factor Ssub(a) (mesophases) are discussed. (orig.)

  20. Experimental and NMR theoretical methodology applied to geometric analysis of the bioactive clerodane trans-dehydrocrotonin

    International Nuclear Information System (INIS)

    trans-Dehydrocrotonin (t-DCTN) a bioactive 19-nor-diterpenoid clerodane type isolated from Croton cajucara Benth, is one of the most investigated clerodane in the current literature. In this work, a new approach joining X-ray diffraction data, nuclear magnetic resonance (NMR) data and theoretical calculations was applied to the thorough characterization of t-DCTN. For that, the geometry of t-DCTN was reevaluated by X-ray diffraction as well as 1H and 13C NMR data, whose geometrical parameters where compared to those obtained from B3LYP/6-311G++(d,p) level of theory. From the evaluation of both calculated and experimental values of 1H and 13C NMR chemical shifts and spin-spin coupling constants, it was found very good correlations between theoretical and experimental magnetic properties of t-DCTN. Additionally, the delocalization indexes between hydrogen atoms correlated accurately with theoretical and experimental spin-spin coupling constants. An additional topological analysis from quantum theory of atoms in molecules (QTAIM) showed intramolecular interactions for t-DCTN. (author)

  1. 69,71Ga and 14N high-field NMR of gallium nitride films

    International Nuclear Information System (INIS)

    Gallium nitride thick films produced by HVPE having varying levels of defects have been characterized by 69,71Ga and 14N NMR at high field (11.7 T). The highest quality film yields the sharpest NMR peaks, from which highly accurate NMR parameters, viz. nuclear quadrupole coupling constants (NQCC), isotropic chemical shifts and chemical shift anisotropies, could be derived from studies as a function of film orientation. Poorer quality films (larger X-ray rocking curve widths) exhibit markedly broader 71Ga satellite transition peaks with a longer T2 relaxation time, and additional high-frequency shoulders or peaks for the central transitions. The linewidths of the14N doublet are also broader in the poorer quality films. The 71Ga spectra of films containing high oxygen levels show a new high-frequency central-transition peak with a very short T1. The high-frequency peaks in all cases may be due to Knight shifts arising from conduction electrons. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Identifying stereoisomers by ab-initio calculation of secondary isotope shifts on NMR chemical shieldings.

    Science.gov (United States)

    Böhm, Karl-Heinz; Banert, Klaus; Auer, Alexander A

    2014-01-01

    We present ab-initio calculations of secondary isotope effects on NMR chemical shieldings. The change of the NMR chemical shift of a certain nucleus that is observed if another nucleus is replaced by a different isotope can be calculated by computing vibrational corrections on the NMR parameters using electronic structure methods. We demonstrate that the accuracy of the computational results is sufficient to even distinguish different conformers. For this purpose, benchmark calculations for fluoro(2-2H)ethane in gauche and antiperiplanar conformation are carried out at the HF, MP2 and CCSD(T) level of theory using basis sets ranging from double- to quadruple-zeta quality. The methodology is applied to the secondary isotope shifts for 2-fluoronorbornane in order to resolve an ambiguity in the literature on the assignment of endo- and exo-2-fluoronorbornanes with deuterium substituents in endo-3 and exo-3 positions, also yielding insight into mechanistic details of the corresponding synthesis. PMID:24762967

  3. 13C NMR study of the stereochemical configuration of PMMA produced by radiation-induced polymerization

    International Nuclear Information System (INIS)

    A 13C NMR method is developed to study the stereochemical configuration of polymethylmethacrylate (PMMA) produced by 60Co ?-radiation-induced polymerization. Seven 13C NMR lines are observed for the carbonyl carbon resonance with excellent resolution at ambient temperature and a field of 20 MHz. A systematic investigation of the effects of radiation on the NMR spectra of the tactic sample shows that the spectrum of the skeletal carbon and that of the ?-CH3 are well resolved. The most striking aspect of the-carba koxy resonance area is that it is clearly resolved into pentads. The triad and pentad distribution can be correlated with the equations of 22 (mm) (??)/(m?)2 = 1. and 44 (1/2m2 - 1/2m + 1)4 (mmmm) (????)/(mmm? + ... = m???) = 1. Bernoullian statistics is applicable to the description of the stereochemical configuration by a single parameter Pm = 0.209. From the data of the triad distribution, the average sequence length n-bar, the meso linkage sequence length n-barm and the racemic linkage sequence length n-bar? are calculated to be 1.27, 1.26 and 5.78 respectively. It is also observed that m-arrangement is favored over ?-arrangement, which might be attributed to the difference in the activation free energy in the formation step

  4. Targeted natural product isolation guided by HPLC-SPE-NMR: Constituents of Hubertia species

    DEFF Research Database (Denmark)

    Sprogoe, K.; Staek, D.

    2007-01-01

    The hyphenated technique, high-performance liquid chromatography-solid-phase extraction-nuclear magnetic resonance spectroscopy (HPLC-SPE-NMR), has been applied for rapid identification of novel natural products in crude extracts of Hubertia ambavilla and Hubertia tomentosa. The technique allowed full or partial identification of all major extract constituents and demonstrated the presence of unusual quinic acid derivatives containing the (1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl residue that exhibit strongly coupled ABXY patterns, the parameters of which were obtained by spin simulations. Using homo- and heteronuclear 2D NMR data acquired in the HPLC-SPE-NMR mode, complete structure determination of three new natural products, i.e., 3,5-di-O-caffeoyl-4-O-[(1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl]quini c acid (1), its 2-hydroxy derivative (2), and 3,5-di-O-caffeoyl-4-O-[(4-hydroxyphenyl)acetyl]quinic acid (3), was performed. Finally, targeted isolation of 1 was achieved by SPE fractionation and preparative HPLC, followed by evaluation of its antioxidant and antimicrobial activity. In contrast to chlorogenic acid and 3,5-di-O-caffeoylquinic acid, which act as antioxidants, compound 1 proved at the same conditions to possess prooxidant activity in an assay evaluating the oxidation of human low-density lipoprotein induced by Cu2+.

  5. In vivo quantitative NMR imaging of fruit tissues during growth using Spoiled Gradient Echo sequence

    DEFF Research Database (Denmark)

    Kenouche, S.; Perrier, M.

    2014-01-01

    Nondestructive studies of physiological processes in agronomic products require increasingly higher spatial and temporal resolutions. Nuclear Magnetic Resonance (NMR) imaging is a non-invasive technique providing physiological and morphological information on biological tissues. The aim of this study was to design a robust and accurate quantitative measurement method based on NMR imaging combined with contrast agent (CA) for mapping and quantifying water transport in growing cherry tomato fruits. A multiple flip-angle Spoiled Gradient Echo (SGE) imaging sequence was used to evaluate the intrinsic parameters maps M 0 and T 1 of the fruit tissues. Water transport and paths flow were monitored using Gd 3+/[Fe(CN)6]3-/D - mannitol nanoparticles as a tracer. This dynamic study was carried out using a compartmental modeling. The CA was preferentially accumulated in the surrounding tissues of columella and in the seed envelopes. The total quantities and the average volume flow of water estimated are: 198 mg, 1.76 mm3/h for the columella and 326 mg, 2.91 mm 3/h for the seed envelopes. We demonstrate in this paper that the NMR imaging technique coupled with efficient and biocompatible CA in physiological medium has the potential to become a major tool in plant physiology research. © 2014 Elsevier Inc.

  6. Experimental and NMR theoretical methodology applied to geometric analysis of the bioactive clerodane trans-dehydrocrotonin

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Breno Almeida; Firme, Caio Lima, E-mail: firme.caio@gmail.com, E-mail: caiofirme@quimica.ufrn.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Instituto de Quimica; Maciel, Maria Aparecida Medeiros [Universidade Potiguar, Natal, RN (Brazil). Programa de Pos-graduacao em Biotecnologia; Kaiser, Carlos R. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica; Schilling, Eduardo; Bortoluzzi, Adailton J. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Quimica

    2014-04-15

    trans-Dehydrocrotonin (t-DCTN) a bioactive 19-nor-diterpenoid clerodane type isolated from Croton cajucara Benth, is one of the most investigated clerodane in the current literature. In this work, a new approach joining X-ray diffraction data, nuclear magnetic resonance (NMR) data and theoretical calculations was applied to the thorough characterization of t-DCTN. For that, the geometry of t-DCTN was reevaluated by X-ray diffraction as well as {sup 1}H and {sup 13}C NMR data, whose geometrical parameters where compared to those obtained from B3LYP/6-311G++(d,p) level of theory. From the evaluation of both calculated and experimental values of {sup 1}H and {sup 13}C NMR chemical shifts and spin-spin coupling constants, it was found very good correlations between theoretical and experimental magnetic properties of t-DCTN. Additionally, the delocalization indexes between hydrogen atoms correlated accurately with theoretical and experimental spin-spin coupling constants. An additional topological analysis from quantum theory of atoms in molecules (QTAIM) showed intramolecular interactions for t-DCTN. (author)

  7. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects.

    Science.gov (United States)

    Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T; Henriksen, O

    1994-02-01

    The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human skeletal muscle, a relationship that is still poorly understood. This study describes the optimization of skeletal muscle 31P-MRS in a whole-body magnet, involving surface coil design, utilization of adiabatic radio frequency pulses and advanced time-domain fitting, to the technical design of SEMG. A nonmagnetic ergometer was used for ankle dorsiflexions that activated only the anterior tibial muscle as verified by post exercise imaging. The coil design and the adiabatic sech/tanh pulse improved sensitivity by 45% and 56% respectively, compared with standard techniques. Simultaneous electromyographic recordings did not deteriorate the NMR spectra. The VARPRO time domain fitting routine was very suitable for estimating 31P muscle spectra. With these methods it was possible to accurately estimate parameters describing metabolic and electrical changes during rest, exercise and the entire recovery period with a 20-s time resolution on a standard 1.5 T whole-body NMR scanner. PMID:8133762

  8. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects.

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C

    1994-01-01

    The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human skeletal muscle, a relationship that is still poorly understood. This study describes the optimization of skeletal muscle 31P-MRS in a whole-body magnet, involving surface coil design, utilization of adiabatic radio frequency pulses and advanced time-domain fitting, to the technical design of SEMG. A nonmagnetic ergometer was used for ankle dorsiflexions that activated only the anterior tibial muscle as verified by post exercise imaging. The coil design and the adiabatic sech/tanh pulse improved sensitivity by 45% and 56% respectively, compared with standard techniques. Simultaneous electromyographic recordings did not deteriorate the NMR spectra. The VARPRO time domain fitting routine was very suitable for estimating 31P muscle spectra. With these methods it was possible to accurately estimate parameters describing metabolic and electrical changes during rest, exercise and the entire recovery period with a 20-s time resolution on a standard 1.5 T whole-body NMR scanner.

  9. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C

    1994-01-01

    The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human skeletal muscle, a relationship that is still poorly understood. This study describes the optimization of skeletal muscle 31P-MRS in a whole-body magnet, involving surface coil design, utilization of adiabatic radio frequency pulses and advanced time-domain fitting, to the technical design of SEMG. A nonmagnetic ergometer was used for ankle dorsiflexions that activated only the anterior tibial muscle as verified by post exercise imaging. The coil design and the adiabatic sech/tanh pulse improved sensitivity by 45% and 56% respectively, compared with standard techniques. Simultaneous electromyographic recordings did not deteriorate the NMR spectra. The VARPRO time domain fitting routine was very suitable for estimating 31P muscle spectra. With these methods it was possible to accurately estimate parameters describing metabolic and electrical changes during rest, exercise and the entire recovery period with a 20-s time resolution on a standard 1.5 T whole-body NMR scanner.

  10. Studies of organic paint binders by NMR spectroscopy

    Science.gov (United States)

    Spyros, A.; Anglos, D.

    2006-06-01

    Nuclear magnetic resonance spectroscopy is applied to the study of aged binding media used in paintings, namely linseed oil, egg tempera and an acrylic medium. High resolution 1D and 2D NMR experiments establish the state of hydrolysis and oxidation of the linseed and egg tempera binders after five years of aging, by determining several markers sensitive to the hydrolytic and oxidative processes of the binder lipid fraction. The composition of the acrylic binder co-polymer is determined by 2D NMR spectroscopy, while the identification of a surfactant, poly(ethylene glycol), found in greater amounts in aged acrylic medium, is reported. The non-destructive nature of the proposed analytical NMR methodology, and minimization of the amount of binder material needed through the use of sophisticated cryoprobes and hyphenated LC-NMR techniques, make NMR attractive for the arts analyst, in view of its rapid nature and experimental simplicity.

  11. $\\beta$-NMR of copper isotopes in ionic liquids

    CERN Multimedia

    We propose to test the feasibility of spin-polarization and $\\beta$-NMR studies on several short-lived copper isotopes, $^{58}$ Cu, $^{74}$Cu and $^{75}$Cu in crystals and liquids. The motivation is given by biological studies of Cu with $\\beta$-NMR in liquid samples, since Cu is present in a large number of enzymes involved in electron transfer and activation of oxygen. The technique is based on spin-polarization via optical pumping in the new VITO beamline. We will use the existing lasers, NMR magnet and NMR chambers and we will prepare a new optical pumping system. The studies will be devoted to tests of achieved $\\beta$-asymmetry in solid hosts, the behaviour of asymmetry when increasing vacuum, and finally NMR scans in ionic liquids. The achieved spin polarization will be also relevant for the plans to measure with high precision the magnetic moments of neutron-rich Cu isotopes.

  12. Metabolomic analysis using optimized NMR and statistical methods.

    Science.gov (United States)

    Araníbar, Nelly; Ott, Karl-Heinz; Roongta, Vikram; Mueller, Luciano

    2006-08-01

    NMR-based metabolomics requires robust automated methodologies, and the accuracy of NMR-based metabolomics data is greatly influenced by the reproducibility of data acquisition and processing methods. Effective water resonance signal suppression and reproducible spectral phasing and baseline traces across series of related samples are crucial for statistical analysis. We assess robustness, repeatability, sensitivity, selectivity, and practicality of commonly used solvent peak suppression methods in the NMR analysis of biofluids with respect to the automated processing of the NMR spectra and the impact of pulse sequence and data processing methods on the sensitivity of pattern recognition and statistical analysis of the metabolite profiles. We introduce two modifications to the excitation sculpting pulse sequence whereby the excitation solvent suppression pulse cascade is preceded by low-power water resonance presaturation pulses during the relaxation delay. Our analysis indicates that combining water presaturation with excitation sculpting water suppression delivers the most reproducible and information-rich NMR spectra of biofluids. PMID:16762305

  13. Membrane Protein Structure and Dynamics from NMR Spectroscopy

    Science.gov (United States)

    Hong, Mei; Zhang, Yuan; Hu, Fanghao

    2012-05-01

    We review the current state of membrane protein structure determination using solid-state nuclear magnetic resonance (NMR) spectroscopy. Multidimensional magic-angle-spinning correlation NMR combined with oriented-sample experiments has made it possible to measure a full panel of structural constraints of membrane proteins directly in lipid bilayers. These constraints include torsion angles, interatomic distances, oligomeric structure, protein dynamics, ligand structure and dynamics, and protein orientation and depth of insertion in the lipid bilayer. Using solid-state NMR, researchers have studied potassium channels, proton channels, Ca2+ pumps, G protein-coupled receptors, bacterial outer membrane proteins, and viral fusion proteins to elucidate their mechanisms of action. Many of these membrane proteins have also been investigated in detergent micelles using solution NMR. Comparison of the solid-state and solution NMR structures provides important insights into the effects of the solubilizing environment on membrane protein structure and dynamics.

  14. Dynamics of solutions and fluid mixtures by NMR

    International Nuclear Information System (INIS)

    After a short introduction to NMR spectroscopy, with a special emphasis on dynamical aspects, an overview on two fundamental aspects of molecular dynamics, NMR relaxation and its relationship with molecular reorientation, and magnetization transfer phenomena induced by molecular rate processes (dynamic NMR) is presented, followed by specific mechanisms of relaxation encountered in paramagnetic systems or with quadrupolar nuclei. Application fields are then reviewed: solvent exchange on metal ions with a variable pressure NMR approach, applications of field gradients in NMR, aggregation phenomena and micro-heterogeneity in surfactant solutions, polymers and biopolymers in the liquid state, liquid-like molecules in rigid matrices and in soft matter (swollen polymers and gels, fluids in and on inorganic materials, food)

  15. Improvements of NMR image quality using adaptive nonlinear filter

    International Nuclear Information System (INIS)

    To improve quality of NMR images, a new method of image processing is proposed. Generally, the effective image processing is performed by using features of images. I have found our two features by examining NMR images: 1) noise of NMR image follows Rayleigh distribution, namely salt-and-pepper noise; 2) its standard deviation is easy to calculate. Utilizing these features, I have proposed an adaptive nonlinear filtering method, which is performed by judging the isolation status of pixels using the standard deviation of the noise in NMR image. This method can reduce noise in NMR images without causing significant blurring. Simulations and a human head image using the proposed method are demonstrated and compared with those using conventional filtering method, showing the effectiveness of the new method. (author)

  16. Analysis of {sup 2}H NMR spectra of water molecules on the surface of nano-silica material MCM-41: Deconvolution of the signal into a Lorentzian and a powder pattern line shapes

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, J., E-mail: jamal.hassan@kustar.ac.ae [Applied Mathematics and Sciences, KUSTAR, UAE and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada)

    2012-01-01

    Water {sup 2}H NMR signal on the surface of nano-silica material MCM-41 consists of two overlapping resonances. The {sup 2}H water spectrum shows a superposition of a Lorentzian line shape and the familiar NMR powder pattern line shape, indicating the existence of two spin components. Exchange occurs between these two groups. Decomposition of the two signals is a crucial starting point to study the exchange process. In this article we have determined these spin component populations along with other important parameters for the {sup 2}H water NMR signal over a temperature range between 223 K and 343 K.

  17. Investigation of zeolites by solid state quadrapole NMR

    International Nuclear Information System (INIS)

    The subject of this thesis is the NMR investigation of zeolites. The nature and properties of zeolites are discussed. Some of the basic priniples of NMR techniques on quadrupole nuclei are presented. A special technique, namely a two-dimensional nutation experiment is discussed in detail. The theory of the nutation experiment for quadrupole spin species with spin quantum number 3/2 as well as 5/2 is presented. For both spin spcies the theoretical spectra are compared with experimental results. It is also shown that the nutation expeirment can be performed with several pulse schemes. It is shown how phase-sensitive pure-absorption nutation spectra can be obtained and an NMR-probe is presented that is capable of performing NMR experiments at high (up to 500 degree C) temperatures. The two-dimensional nutation NMR technique has been applied to sodium cations in zeolite NaA. For this purpose a numbre of zeolite samples were prepared that contained different amounts of water. With the aid of nutation NMR the hydration of the zeolite can be studied and conclusions can be drawn about the symmetry of the surrounding of the sodium cations. With the aid of an extension of the nutation NMR experiment: Rotary Echo Nutation NMR, it is shown that in zeolite NaA, in various stages of hydration, the sodium cations or water molecules are mobile. Proof is given by means of high-temperature 23Na-NMR that dehydrates zeolite NaA undergoes a phase transition at ca. 120 degree C. In a high-temperature NMR investigation of zeolite ZSM-5 it is shown that the sodium ions start to execute motions when the temperature is increased. (author). 198 refs.; 72 figs.; 6 tabs

  18. Variations of NMR signals by hyperpolarization and ultrasound; Variation von NMR-Signalen durch Hyperpolarisation und Ultraschall

    Energy Technology Data Exchange (ETDEWEB)

    Engelbertz, A.

    2006-07-01

    In this thesis it is described how p-NMR can be applied to metals with verlo low hydrogen concentrations and how a combination of ultrasound and NMR can lead to an improvement of the measureing method. As examples measurements on H{sub 2}O and ethanol are described. (HSI)

  19. Microscopic origins of the zero-field splitting parameters for 6S(3d5) state ions at tetragonal symmetry crystal field

    International Nuclear Information System (INIS)

    The microscopic origin of the zero-field splitting (ZFS) parameters including D and (a+2F/3), for 6S(3d5) state ion at tetragonal symmetry crystal field (CF), taking into account the electronic magnetic interactions, i.e. the spin-spin (SS), the spin-other-orbit (SOO), and the orbit-orbit (OO) interactions, besides the well-known spin-orbit (SO) interaction, have been investigated using the complete diagonalization method (CDM) and the microscopic spin Hamiltonian theory. Although the SO mechanism is the most important one, the contributions to the ZFS parameters D and (a+2F/3) due to the four additional mechanisms: SS, SOO, OO, and the combined SO?SS?SOO?OO coupling mechanism, are appreciable and shall not be omitted. The individual contributions to the ZFS parameters arising from the spin quartet states and the spin doublet states have been analyzed. It is shown that the ZFS parameters D and (a+2F/3) arise from the spin quartet states as well as the combined effects between the spin doublet states and the spin quartets states, whereas the contributions to D and (a+2F/3) from the spin doublet states are zero. Our investigations show that the rank-2 ZFS parameter D primarily results from the spin quartet states, whereas the rank-4 ZFS parameter (a+2F/3) primarily results from the combined effects between the spin doublet states and the spin quartet states. The contributions to the rank-2 ZFS parameter D from the net spin quartet states excerom the net spin quartet states exceed 95% and the contributions to the rank-4 ZFS parameter (a+2F/3) from the combined effects between the spin doublet states and the spin quartet states exceed 88.2% for the selected ranges of the crystal field parameters. The dependence of the ZFS parameters D and (a+2F/3) on the CF parameters Dq, B20, and Bl40 for 6S(3d5) state ions at tetragonal symmetry have been studied. It is found that the relations hold: |D(-Dq)|?-|D(Dq)|, (a+2F/3)(-Dq)?(a+2F/3)(-Dq) for |Dq|>800 cm-1. The illustrative evaluation is performed for typical crystal materials: Mn2+: Rb2CdF4, Mn2+: K2MgF4, and Mn2+: K2ZnF4 crystals. The good agreements between the theoretical values and the experimental finding are obtained.

  20. Structural investigation of molten fluorides of nuclear interest by NMR and XAFS spectroscopies

    International Nuclear Information System (INIS)

    In the frame of the renewal of the different nuclear plans, the molten salt reactor is one of the six concepts of reactors of 4. generation. This reactor has the particularity to use a liquid fuel based on LiF-ThF4 mixtures. In order to develop and to optimize this concept, it is important to characterize the structure of the melt and to describe its physical and chemical properties. Our work has been based on the study of the system MF-ZrF4 (M = Li, Na, K) selected as a model of ThF4 based systems. We have combined two spectroscopic techniques, the Nuclear Magnetic Resonance and the X-ray Absorption at high temperature, with molecular dynamics calculations. We particularly focused on the local environments of the fluorine and the zirconium. In order to interpret the NMR data obtain in the molten state, we performed a preliminary study on zirconium halides and rare earth and alkali fluoro zirconates using the 91Zr solid-state NMR at very high magnetic fields. New correlations between structural parameters and NMR data have been established. At high temperature, in MF-ZrF4 melts we have shown the coexistence of three different kind of Zr-based complexes with different proportions depending on the amount of ZrF4 and on the nature of the alkali. Depending on the ZrF4 content, three kinds of fluorine have been characterized: form free fluorines at low amount of zirconium fluorides, fluorines involved in Zr-based complexes and bridging fluorines at higher ZrF4 content. This original and innovative approach of molten fluorides mixtures, combining NMR and EXAFS at high temperature with molecular dynamics calculations, is very efficient to describe their speciation and thus their fluoro-acidity. (author)