WorldWideScience

Sample records for surfaces wide-line nmr

  1. Determination of oil in seeds by a wide line NMR instrument

    International Nuclear Information System (INIS)

    Marton, Aurel

    1983-01-01

    The oil content of sunflower, rape and soybean seeds was determined by a wide line NMR instrument. Using various model systems the following conclusions were drawn: the sensitivity of the instrument is much higher for the oil content of the seeds than for their water content. This observation can be interpreted in terms of the longer relaxation time of the water protons. The quantitative determination of the oil content of the seeds can be done with a high accuracy provided that the calibration curve for the respective oil is available and the signal of the solid state components of the seeds is corrected. If the water content of the seeds is reduced below 5 per cent, the oil content values obtained by NMR and extraction techniques are in agreement within the experimental error. (author)

  2. Relaxation time estimation in surface NMR

    Science.gov (United States)

    Grunewald, Elliot D.; Walsh, David O.

    2017-03-21

    NMR relaxation time estimation methods and corresponding apparatus generate two or more alternating current transmit pulses with arbitrary amplitudes, time delays, and relative phases; apply a surface NMR acquisition scheme in which initial preparatory pulses, the properties of which may be fixed across a set of multiple acquisition sequence, are transmitted at the start of each acquisition sequence and are followed by one or more depth sensitive pulses, the pulse moments of which are varied across the set of multiple acquisition sequences; and apply processing techniques in which recorded NMR response data are used to estimate NMR properties and the relaxation times T.sub.1 and T.sub.2* as a function of position as well as one-dimensional and two-dimension distributions of T.sub.1 versus T.sub.2* as a function of subsurface position.

  3. Nested Surface Coils for Multinuclear NMR

    OpenAIRE

    Magill, Arthur; Gruetter, Rolf

    2011-01-01

    This article introduces the design of surface coils for multinuclear applications. The relative sensitivities of several NMR-visible nuclei of biological interest are considered, and the motivations to operate an RF coil at multiple frequencies, both sequentially and simultaneously, are reviewed. The design of nested surface coils is then developed. Magnetic fields generated by planar loop and butterfly coils are first introduced. The benefits of quadrature design are briefly considered, and ...

  4. NMR

    International Nuclear Information System (INIS)

    Kneeland, J.B.; Lee, B.C.P.; Whalen, J.P.; Knowles, R.J.R.; Cahill, P.T.

    1984-01-01

    Although still quite new, NMR imaging has already emerged as a safe, noninvasive, painless, and effective diagnostic modality requiring no ionizing radiation. Also, NMR appears already to have established itself as the method of choice for the examination of the brain spinal cord (excluding herniated disks). Another area in which NMR excels is in the examination of the pelvis. The use of surface coils offers the promise of visualizing structures with resolution unobtainable by any other means. In addition, NMR, with its superb visualization of vascular structures and potential ability to measure flow, may soon revolutionize the diagnosis of cardiovascular disease. Finally, NMR, through biochemically and physiologically based T/sub 1/ and T/sub 2/ indices or through spectroscopy, may provide a means of monitoring therapeutic response so as to permit tailoring of treatment to the individual patient. In short, NMR is today probably at the same stage as the x-ray was in Roentgen's day

  5. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva

    2016-08-15

    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  6. Wettability of quartz surface as observed by NMR transverse relaxation time (T2)

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Katika, Konstantina; Fabricius, Ida Lykke

    the wettability property of quartz surface by using Nuclear Magnetic Resonance (NMR) method. The principle of this method is that protons in water relax faster when it comes close to solid surface. We observed that quart is highly water wet. A layer of water (bound water) forms on the quartz surface when...

  7. Phosphorus solubility of agricultural soils: a surface charge and phosphorus-31 NMR speciation study

    Science.gov (United States)

    We investigated ten soils from six states in United States to determine the relationship between potentiometric titration derived soil surface charge and Phosphorus-31 (P) nuclear magnetic resonance (NMR) speciation with the concentration of water-extractable P (WEP). The surface charge value at the...

  8. Characterization of Silicon Nanocrystal Surfaces by Multidimensional Solid-State NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hanrahan, Michael P. [Department; US DOE Ames Laboratory, Ames, Iowa 50011, United States; Fought, Ellie L. [Department; Windus, Theresa L. [Department; Wheeler, Lance M. [Chemistry; Anderson, Nicholas C. [Chemistry; Neale, Nathan R. [Chemistry; Rossini, Aaron J. [Department; US DOE Ames Laboratory, Ames, Iowa 50011, United States

    2017-11-17

    The chemical and photophysical properties of silicon nanocrystals (Si NCs) are strongly dependent on the chemical composition and structure of their surfaces. Here we use fast magic angle spinning (MAS) and proton detection to enable the rapid acquisition of dipolar and scalar 2D 1H-29Si heteronuclear correlation (HETCOR) solid-state NMR spectra and reveal a molecular picture of hydride-terminated and alkyl-functionalized surfaces of Si NCs produced in a nonthermal plasma. 2D 1H-29Si HETCOR and dipolar 2D 1H-1H multiple-quantum correlation spectra illustrate that resonances from surface mono-, di-, and trihydride groups cannot be resolved, contrary to previous literature assignments. Instead the 2D NMR spectra illustrate that there is large distribution of 1H and 29Si chemical shifts for the surface hydride species in both the as-synthesized and functionalized Si NCs. However, proton-detected 1H-29Si refocused INEPT experiments can be used to unambiguously differentiate NMR signals from the different surface hydrides. Varying the 29Si evolution time in refocused INEPT experiments and fitting the oscillation of the NMR signals allows for the relative populations of the different surface hydrides to be estimated. This analysis confirms that monohydride species are the predominant surface species on the as-synthesized Si NCs. A reduction in the populations of the di- and trihydrides is observed upon functionalization with alkyl groups, consistent with our previous hypothesis that the trihydride, or silyl (*SiH3), group is primarily responsible for initiating surface functionalization reactions. Density functional theory (DFT) calculations were used to obtain quantum chemical structural models of the Si NC surface and reproduce the observed 1H and 29Si chemical shifts. The approaches outlined here will be useful to obtain a more detailed picture of surface structures for Si NCs and other hydride-passivated nanomaterials.

  9. Quantification of C=C and C=O Surface Carbons in Detonation Nanodiamond by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J -F; Fang, X -W; Schmidt-Rohr, K

    2014-05-08

    The ability of solid-state 13C NMR to detect and quantify small amounts of sp2-hybridized carbon on the surface of ~5 nm diameter nanodiamond particles is demonstrated. The C=C carbon fraction is only 1.1 ± 0.4% in pristine purified detonation nanodiamond, while a full single-layer graphitic or “bucky diamond” shell would contain ca. 25% of all C in a 5 nm diameter particle. Instead of large aromatic patches repeatedly proposed in the recent literature, sp3-hybridized CH and COH carbons cover most of the nanodiamond particle surface, accounting for ~5% each. C=O and COO groups also seen in X-ray absorption near-edge structure spectroscopy (XANES) but not detected in previous NMR studies make up ca. 1.5% of all C. They are removed by heat treatment at 800 °C, which increases the aromatic fraction. 13C{1H} NMR demonstrates that the various sp2-hybridized carbons are mostly not protonated, but cross-polarization shows that they are separated from 1H by only a few bond lengths, which proves that they are near the protonated surface. Together, the observed C–H, C–OH, C=O, and C=C groups account for 12–14% of all C, which matches the surface fraction expected for bulk-terminated 5 nm diameter diamond particles.

  10. NMR investigations of surfaces and interfaces using spin-polarized xenon

    Energy Technology Data Exchange (ETDEWEB)

    Gaede, Holly Caroline [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1995-07-01

    129Xe NMR is potentially useful for the investigation of material surfaces, but has been limited to high surface area samples in which sufficient xenon can be loaded to achieve acceptable signal to noise ratios. In Chapter 2 conventional 129Xe NMR is used to study a high surface area polymer, a catalyst, and a confined liquid crystal to determine the topology of these systems. Further information about the spatial proximity of different sites of the catalyst and liquid crystal systems is determined through two dimensional exchange NMR in Chapter 3. Lower surface area systems may be investigated with spin-polarized xenon, which may be achieved through optical pumping and spin exchange. Optically polarized xenon can be up to 105times more sensitive than thermally polarized xenon. In Chapter 4 highly polarized xenon is used to examine the surface of poly(acrylonitrile) and the formation of xenon clathrate hydrates. An attractive use of polarized xenon is as a magnetization source in cross polarization experiments. Cross polarization from adsorbed polarized xenon may allow detection of surface nuclei with drastic enhancements. A non-selective low field thermal mixing technique is used to enhance the 13C signal of CO2 of xenon occluded in solid CO2 by a factor of 200. High-field cross polarization from xenon to proton on the surface of high surface area polymers has enabled signal enhancements of ~1,000. These studies, together with investigations of the efficiency of the cross polarization process from polarized xenon, are discussed in Chapter 5. Another use of polarized xenon is as an imaging contrast agent in systems that are not compatible with traditional contrast agents. The resolution attainable with this method is determined through images of structured phantoms in Chapter 6.

  11. Spatial selectivity of the surface coils used in-vivo in NMR spectroscopy

    International Nuclear Information System (INIS)

    Laval, M.; Decorps, M.; Chaillout, J.J.; Confort, S.

    1984-05-01

    Surface coils are being to be of current use in ''in vivo'' NMR spectroscopy. This kind of resonator yields indeed a very good signal to noise ratio when applied to the examination of limited and superficial regions of large organs. But to allow the biological analysis of detected signals, knowledge of the spatial response is necessary. Radiofrequency isofield surfaces, associated with sensitivity curve computed along the coil axis, give a good idea of analysed volume by surface coils. On the other hand, saturation sequence previously applied to excitation pulse is suggested to make the spatial response of surface coil independant of T 1 relaxation time constant of different chemical species within the sample. A short survey on chemical shift imaging either with surface coils or with uniform radiofrequency field resonator is presented in conclusion [fr

  12. Characterizing electrocatalytic surfaces: Electrochemical and NMR studies of methanol and carbon monoxide on Pt/C

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, Patrick; Fojas, Aurora Marie; Rush, Benjamin; Reimer, Jeffrey A.; Cairns, Elton J. [Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720 (United States)

    2007-12-20

    We use cyclic voltammetry (CV) on fuel cell electrodes to elucidate the important differences between adsorbates resulting from carbon monoxide adsorption and methanol adsorption onto commercial Pt/C electrocatalysts in a sulfuric acid electrolyte. Under open circuit conditions, methanol was found to adsorb preferentially onto the Pt sites associated with 'strongly bound' hydrogen. The sites associated with 'weakly bound' hydrogen adsorbed methanol more slowly. In the case of CO adsorption, which requires no adsorbate dehydrogenation, all adsorption sites showed similar affinity towards the adsorbate. Electrochemical oxidation of the adsorbates derived from both methanol and CO exposure exhibit slower oxidation when the adsorbate is associated with cubic-packed-like sites than from close-packed-steps and other sites. NMR of a {sup 13}CO-adlayer prepared by electrochemical adsorption from low concentration {sup 13}CH{sub 3}OH shows a lower NMR shift and smaller linewidth than the previously reported values for electrochemically adsorbed {sup 13}CO gas. These results are interpreted in terms of adsorbate motion on the electrocatalyst surface. (author)

  13. The Surface of Nanoparticle Silicon as Studied by Solid-State NMR

    Directory of Open Access Journals (Sweden)

    Gary E. Maciel

    2012-12-01

    Full Text Available The surface structure and adjacent interior of commercially available silicon nanopowder (np-Si was studied using multinuclear, solid-state NMR spectroscopy. The results are consistent with an overall picture in which the bulk of the np-Si interior consists of highly ordered (“crystalline” silicon atoms, each bound tetrahedrally to four other silicon atoms. From a combination of 1H, 29Si and 2H magic-angle-spinning (MAS NMR results and quantum mechanical 29Si chemical shift calculations, silicon atoms on the surface of “as-received” np-Si were found to exist in a variety of chemical structures, with apparent populations in the order (a (Si–O–3Si–H > (b (Si–O–3SiOH > (c (HO–nSi(Sim(–OSi4−m−n ≈ (d (Si–O–2Si(HOH > (e (Si–O–2Si(–OH2 > (f (Si–O–4Si, where Si stands for a surface silicon atom and Si represents another silicon atom that is attached to Si by either a Si–Si bond or a Si–O–Si linkage. The relative populations of each of these structures can be modified by chemical treatment, including with O2 gas at elevated temperature. A deliberately oxidized sample displays an increased population of (Si–O–3Si–H, as well as (Si–O–3SiOH sites. Considerable heterogeneity of some surface structures was observed. A combination of 1H and 2H MAS experiments provide evidence for a substantial population of silanol (Si–OH moieties, some of which are not readily H-exchangeable, along with the dominant Si–H sites, on the surface of “as-received” np-Si; the silanol moieties are enhanced by deliberate oxidation. An extension of the DEPTH background suppression method is also demonstrated that permits measurement of the T2 relaxation parameter simultaneously with background suppression.

  14. Mapping the surface of Escherichia coli peptide deformylase by NMR with organic solvents.

    Science.gov (United States)

    Byerly, Douglas W; McElroy, Craig A; Foster, Mark P

    2002-07-01

    Identifying potential ligand binding sites on a protein surface is an important first step for targeted structure-based drug discovery. While performing control experiments with Escherichia coli peptide deformylase (PDF), we noted that the organic solvents used to solubilize some ligands perturbed many of the same resonances in PDF as the small molecule inhibitors. To further explore this observation, we recorded (15)N HSQC spectra of E. coli peptide deformylase (PDF) in the presence of trace quantities of several simple organic solvents (acetone, DMSO, ethanol, isopropanol) and identified their sites of interaction from local perturbation of amide chemical shifts. Analysis of the protein surface structure revealed that the ligand-induced shift perturbations map to the active site and one additional surface pocket. The correlation between sites of solvent and inhibitor binding highlights the utility of organic solvents to rapidly and effectively validate and characterize binding sites on proteins prior to designing a drug discovery screen. Further, the solvent-induced perturbations have implications for the use of organic solvents to dissolve candidate ligands in NMR-based screens.

  15. Trans and surface membrane bound zervamicin IIB: 13C-MAOSS-NMR at high spinning speed

    International Nuclear Information System (INIS)

    Raap, J.; Hollander, J.; Ovchinnikova, T. V.; Swischeva, N. V.; Skladnev, D.; Kiihne, S.

    2006-01-01

    Interactions between 15 N-labelled peptides or proteins and lipids can be investigated using membranes aligned on a thin polymer film, which is rolled into a cylinder and inserted into the MAS-NMR rotor. This can be spun at high speed, which is often useful at high field strengths. Unfortunately, substrate films like commercially available polycarbonate or PEEK produce severe overlap with peptide and protein signals in 13 C-MAOSS NMR spectra. We show that a simple house hold foil support allows clear observation of the carbonyl, aromatic and C α signals of peptides and proteins as well as the ester carbonyl and choline signals of phosphocholine lipids. The utility of the new substrate is validated in applications to the membrane active peptide zervamicin IIB. The stability and macroscopic ordering of thin PC10 bilayers was compared with that of thicker POPC bilayers, both supported on the household foil. Sidebands in the 31 P-spectra showed a high degree of alignment of both the supported POPC and PC10 lipid molecules. Compared with POPC, the PC10 lipids are slightly more disordered, most likely due to the increased mobilities of the shorter lipid molecules. This mobility prevents PC10 from forming stable vesicles for MAS studies. The 13 C-peptide peaks were selectively detected in a 13 C-detected 1 H-spin diffusion experiment. Qualitative analysis of build-up curves obtained for different mixing times allowed the transmembrane peptide in PC10 to be distinguished from the surface bound topology in POPC. The 13 C-MAOSS results thus independently confirms previous findings from 15 N spectroscopy [Bechinger, B., Skladnev, D.A., Ogrel, A., Li, X., Rogozhkina, E.V., Ovchinnikova, T.V., O'Neil, J.D.J. and Raap, J. (2001) Biochemistry, 40, 9428-9437]. In summary, application of house hold foil opens the possibility of measuring high resolution 13 C-NMR spectra of peptides and proteins in well ordered membranes, which are required to determine the secondary and

  16. NMR detection and characterization of sialylated glycoproteins and cell surface polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Barb, Adam W. [University of Georgia, Complex Carbohydrate Research Center (United States); Freedberg, Daron I.; Battistel, Marcos D. [Center for Biologics Evaluation and Research, Food and Drug Administration, Laboratory of Bacterial Polysaccharides (United States); Prestegard, James H., E-mail: jpresteg@ccrc.uga.edu [University of Georgia, Complex Carbohydrate Research Center (United States)

    2011-09-15

    Few solution NMR pulse sequences exist that are explicitly designed to characterize carbohydrates (glycans). This is despite the essential role carbohydrate motifs play in cell-cell communication, microbial pathogenesis, autoimmune disease progression and cancer metastasis, and despite that fact that glycans, often shed to extra-cellular fluids, can be diagnostic of disease. Here we present a suite of two dimensional coherence experiments to measure three different correlations (H3-C2, H3-C1, and C1-C2) on sialic acids, a group of nine-carbon carbohydrates found on eukaryotic cell surfaces that often play a key role in disease processes. The chemical shifts of the H3, C2, and C1 nuclei of sialic acids are sensitive to carbohydrate linkage, linkage conformation, and ionization state of the C1 carboxylate. The experiments reported include rigorous filter elements to enable detection and characterization of isotopically labeled sialic acids with high sensitivity in living cells and crude isolates with minimal interference from unwanted signals arising from the {approx}1% {sup 13}C-natural abundance of cellular metabolites. Application is illustrated with detection of sialic acids on living cells, in unpurified mixtures, and at the terminus of the N-glycan on the 55 kDa immunoglobulin G Fc.

  17. NMR detection and characterization of sialylated glycoproteins and cell surface polysaccharides

    International Nuclear Information System (INIS)

    Barb, Adam W.; Freedberg, Darón I.; Battistel, Marcos D.; Prestegard, James H.

    2011-01-01

    Few solution NMR pulse sequences exist that are explicitly designed to characterize carbohydrates (glycans). This is despite the essential role carbohydrate motifs play in cell–cell communication, microbial pathogenesis, autoimmune disease progression and cancer metastasis, and despite that fact that glycans, often shed to extra-cellular fluids, can be diagnostic of disease. Here we present a suite of two dimensional coherence experiments to measure three different correlations (H3–C2, H3–C1, and C1–C2) on sialic acids, a group of nine-carbon carbohydrates found on eukaryotic cell surfaces that often play a key role in disease processes. The chemical shifts of the H3, C2, and C1 nuclei of sialic acids are sensitive to carbohydrate linkage, linkage conformation, and ionization state of the C1 carboxylate. The experiments reported include rigorous filter elements to enable detection and characterization of isotopically labeled sialic acids with high sensitivity in living cells and crude isolates with minimal interference from unwanted signals arising from the ∼1% 13 C-natural abundance of cellular metabolites. Application is illustrated with detection of sialic acids on living cells, in unpurified mixtures, and at the terminus of the N-glycan on the 55 kDa immunoglobulin G Fc.

  18. Changes in Specific Surface as observed by NMR, caused by saturation of Chalk with porewater bearing divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Addassi, Mouadh; Alam, Mohammad Monzurul

    2014-01-01

    Nuclear Magnetic Resonance (NMR) spectrometry has proved to be a good technique for determining the petrophysical properties of reservoir rocks; such as porosity and pore size distribution. We investigated how pore water rich in divalent ions affect the NMR signal from chalk with two different...... samples where precipitation takes place were found to show shifts in the T2 relaxation curve due to the creation of crystals. We were able to identify how differences in the rock texture and precipitants within the pore space may affect the transverse relaxation time by altering the surface......-to-volume ratio of the pore space. The results of this work could benefit the ongoing study on the optimization of the water composition for Enhanced Oil Recovery (EOR) methods and shed light on how it can affect the mechanical and physical properties of the rock....

  19. Structural models of activated γ-alumina surfaces revisited: Thermodynamics, NMR and IR spectroscopies from ab initio calculations

    International Nuclear Information System (INIS)

    Ferreira, Ary R.; Küçükbenli, Emine; Gironcoli, Stefano de; Souza, Wladmir F.; Chiaro, Sandra Shirley X.; Konstantinova, Elena; Leitão, Alexandre A.

    2013-01-01

    Highlights: • Some γ-Alumina surface models already reported in the literature were revisited. • From statistical thermodynamics experimental volcano-type curve was simulated. • From GIPAW calculations H-1 MAS NMR spectra also could be simulated. - Abstract: The activation of highly catalytic γ-alumina surfaces by thermal treatment and the description of the related chemical processes at atomic scale is a topical issue. According to a recent study [J. Am. Chem. Soc. 134 (2012) 14430], the enhanced reactivity of γ-alumina has been associated to tri-coordinated aluminum sites which supposedly are exposed exclusively on the (1 1 0) surfaces of this oxide. In this work, we explore this possibility by modeling the (1 0 0) and (1 1 0) terminations using Krokidis et al. [J. Phys. Chem. B 105 (2001) 5121] bulk structure and performing an extensive search of the most stable hydrated surface models at conditions consistent with experiment. Among the 156 structures analyzed, we identify several “metastable” models for the (1 1 0) surface with a considerable probability of containing the Al III centers at OH coverages of 9.0 and 6.0 OH/nm 2 . We then test the reactivity of these sites through their Lewis acidity by simulating the CO adsorbtion on the surface and our results confirm the high reactivity of Al III centers. Based on the Gibbs free energy of the explored structures, we carry on a thermodynamical analysis at varying hydroxylation degrees and pretreatment temperatures and simulate the experimental volcano-type behavior reported in [J. Am. Chem. Soc. 134 (2012) 14430] and predict the optimum pretreatment temperature as 700 °C, in very good agreement with experimental findings. We further use infrared and solid state MAS NMR spectroscopies and reproduce the 1 H MAS NMR spectra under high vacuum conditions (10 -5 Torr). The strong resemblance of spectra to the experimental ones in the literature [J. Phys. Chem. C 116 (2012) 834] validate further the

  20. Structural models of activated γ-alumina surfaces revisited: Thermodynamics, NMR and IR spectroscopies from ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Ary R. [Universidade Federal de Juiz de Fora (UFJF), Department of Chemistry, Juiz de Fora, MG 36036-330 (Brazil); Küçükbenli, Emine [École Polytechnique Fédérale de Lausanne (EPFL), STI IMX THEOS, CH-1015 Lausanne (Switzerland); Gironcoli, Stefano de [Scuola Internazionale Superiore di Studi Avanzati (SISSA), Condensed Matter Theory Sector, Via Bonomea 265, I-34136 Trieste (Italy); CNR-IOM DEMOCRITOS Simulation Center, Via Bonomea 265, I-34136 Trieste (Italy); Souza, Wladmir F.; Chiaro, Sandra Shirley X. [PETROBRAS-CENPES, Ilha do Fundão, Rio de Janeiro, RJ 21941-915 (Brazil); Konstantinova, Elena [IFSudeste MG, Department of Natural Sciences, Juiz de Fora, MG 36080-001 (Brazil); Leitão, Alexandre A., E-mail: alexandre.leitao@ufjf.edu.br [Universidade Federal de Juiz de Fora (UFJF), Department of Chemistry, Juiz de Fora, MG 36036-330 (Brazil)

    2013-09-23

    Highlights: • Some γ-Alumina surface models already reported in the literature were revisited. • From statistical thermodynamics experimental volcano-type curve was simulated. • From GIPAW calculations H-1 MAS NMR spectra also could be simulated. - Abstract: The activation of highly catalytic γ-alumina surfaces by thermal treatment and the description of the related chemical processes at atomic scale is a topical issue. According to a recent study [J. Am. Chem. Soc. 134 (2012) 14430], the enhanced reactivity of γ-alumina has been associated to tri-coordinated aluminum sites which supposedly are exposed exclusively on the (1 1 0) surfaces of this oxide. In this work, we explore this possibility by modeling the (1 0 0) and (1 1 0) terminations using Krokidis et al. [J. Phys. Chem. B 105 (2001) 5121] bulk structure and performing an extensive search of the most stable hydrated surface models at conditions consistent with experiment. Among the 156 structures analyzed, we identify several “metastable” models for the (1 1 0) surface with a considerable probability of containing the Al{sub III} centers at OH coverages of 9.0 and 6.0 OH/nm{sup 2}. We then test the reactivity of these sites through their Lewis acidity by simulating the CO adsorbtion on the surface and our results confirm the high reactivity of Al{sub III} centers. Based on the Gibbs free energy of the explored structures, we carry on a thermodynamical analysis at varying hydroxylation degrees and pretreatment temperatures and simulate the experimental volcano-type behavior reported in [J. Am. Chem. Soc. 134 (2012) 14430] and predict the optimum pretreatment temperature as 700 °C, in very good agreement with experimental findings. We further use infrared and solid state MAS NMR spectroscopies and reproduce the {sup 1}H MAS NMR spectra under high vacuum conditions (10{sup -5} Torr). The strong resemblance of spectra to the experimental ones in the literature [J. Phys. Chem. C 116 (2012) 834

  1. Structural models of activated γ-alumina surfaces revisited: Thermodynamics, NMR and IR spectroscopies from ab initio calculations

    Science.gov (United States)

    Ferreira, Ary R.; Küçükbenli, Emine; de Gironcoli, Stefano; Souza, Wladmir F.; Chiaro, Sandra Shirley X.; Konstantinova, Elena; Leitão, Alexandre A.

    2013-09-01

    The activation of highly catalytic γ-alumina surfaces by thermal treatment and the description of the related chemical processes at atomic scale is a topical issue. According to a recent study [J. Am. Chem. Soc. 134 (2012) 14430], the enhanced reactivity of γ-alumina has been associated to tri-coordinated aluminum sites which supposedly are exposed exclusively on the (1 1 0) surfaces of this oxide. In this work, we explore this possibility by modeling the (1 0 0) and (1 1 0) terminations using Krokidis et al. [J. Phys. Chem. B 105 (2001) 5121] bulk structure and performing an extensive search of the most stable hydrated surface models at conditions consistent with experiment. Among the 156 structures analyzed, we identify several “metastable” models for the (1 1 0) surface with a considerable probability of containing the AlIII centers at OH coverages of 9.0 and 6.0 OH/nm2. We then test the reactivity of these sites through their Lewis acidity by simulating the CO adsorbtion on the surface and our results confirm the high reactivity of AlIII centers. Based on the Gibbs free energy of the explored structures, we carry on a thermodynamical analysis at varying hydroxylation degrees and pretreatment temperatures and simulate the experimental volcano-type behavior reported in [J. Am. Chem. Soc. 134 (2012) 14430] and predict the optimum pretreatment temperature as 700 °C, in very good agreement with experimental findings. We further use infrared and solid state MAS NMR spectroscopies and reproduce the 1H MAS NMR spectra under high vacuum conditions (10-5 Torr). The strong resemblance of spectra to the experimental ones in the literature [J. Phys. Chem. C 116 (2012) 834] validate further the structural models we have generated in this study.

  2. High resolution NMR spectroscopy of synthetic polymers in bulk

    International Nuclear Information System (INIS)

    Komorski, R.A.

    1986-01-01

    The contents of this book are: Overview of high-resolution NMR of solid polymers; High-resolution NMR of glassy amorphous polymers; Carbon-13 solid-state NMR of semicrystalline polymers; Conformational analysis of polymers of solid-state NMR; High-resolution NMR studies of oriented polymers; High-resolution solid-state NMR of protons in polymers; and Deuterium NMR of solid polymers. This work brings together the various approaches for high-resolution NMR studies of bulk polymers into one volume. Heavy emphasis is, of course, given to 13C NMR studies both above and below Tg. Standard high-power pulse and wide-line techniques are not covered

  3. Polymer binding to carbon nanotubes in aqueous dispersions: residence time on the nanotube surface as obtained by NMR diffusometry.

    Science.gov (United States)

    Frise, Anton E; Pagès, Guilhem; Shtein, Michael; Pri Bar, Ilan; Regev, Oren; Furó, István

    2012-03-08

    The binding of block copolymer Pluronic F-127 in aqueous dispersions of single- (SWCNT) and multiwalled (MWCNT) carbon nanotubes has been studied by pulsed-field-gradient (PFG) (1)H NMR spectroscopy. We show that a major fraction of polymers exist as a free species while a minor fraction is bound to the carbon nanotubes (CNT). The polymers exchange between these two states with residence times on the nanotube surface of 24 ± 5 ms for SWCNT and of 54 ± 11 ms for MWCNT. The CNT concentration in the solution was determined by improved thermal gravimetric analysis (TGA) indicating that the concentration of SWCNT dispersed by F-127 was significantly higher than that for MWCNT. For SWCNT, the area per adsorbed Pluronic F-127 molecule is estimated to be about 40 nm(2).

  4. Adiabatic sweep pulses for earth's field NMR with a surface coil

    Science.gov (United States)

    Conradi, Mark S.; Altobelli, Stephen A.; Sowko, Nicholas J.; Conradi, Susan H.; Fukushima, Eiichi

    2018-03-01

    Adiabatic NMR sweep pulses are described for inversion and excitation in very low magnetic fields B0 and with broad distribution of excitation field amplitude B1. Two aspects distinguish the low field case: (1) when B1 is comparable to or greater than B0, the rotating field approximation fails and (2) inversion sweeps cannot extend to values well below the Larmor frequency because they would approach or pass through zero frequency. Three approaches to inversion are described. The first is a conventional tangent frequency sweep down to the Larmor frequency, a 180° phase shift, and a sweep back up to the starting frequency. The other two are combined frequency and amplitude sweeps covering a narrower frequency range; one is a symmetric sweep from above to below the Larmor frequency and the other uses a smooth decrease of B1 immediately before and after the 180° phase shift. These two AM/FM sweeps show excellent inversion efficiencies over a wide range of B1, a factor of 30 or more. We also demonstrate an excitation sweep that works well in the presence of the same wide range of B1. We show that the primary effect of the counter-rotating field (i.e., at low B0) is that the magnetization suffers large, periodic deviations from where it would be at large B0. Thus, successful sweep pulses must avoid any sharp features in the amplitude, phase, or frequency.

  5. Reassessment of MxiH subunit orientation and fold within native Shigella T3SS needles using surface labelling and solid-state NMR.

    Science.gov (United States)

    Verasdonck, Joeri; Shen, Da-Kang; Treadgold, Alexander; Arthur, Christopher; Böckmann, Anja; Meier, Beat H; Blocker, Ariel J

    2015-12-01

    T3SSs are essential virulence determinants of many Gram-negative bacteria, used to inject bacterial effectors of virulence into eukaryotic host cells. Their major extracellular portion, a ∼50 nm hollow, needle-like structure, is essential to host cell sensing and the conduit for effector secretion. It is formed of a small, conserved subunit arranged as a helical polymer. The structure of the subunit has been studied by electron cryomicroscopy within native polymers and by solid-state NMR in recombinant polymers, yielding two incompatible atomic models. To resolve this controversy, we re-examined the native polymer used for electron cryomicroscopy via surface labelling and solid-state NMR. Our data show the orientation and overall fold of the subunit within this polymer is as established by solid-state NMR for recombinant polymers. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study

    Energy Technology Data Exchange (ETDEWEB)

    Ok, Salim; Hoyt, David W.; Andersen, Amity; Sheets, Julie; Welch, Susan A.; Cole, David R.; Mueller, Karl T.; Washton, Nancy M.

    2017-01-18

    Characterization and modeling of the molecular-level behavior of simple hydrocarbon gases, such as methane, in the presence of both nonporous and nano-porous mineral matrices allows for predictive understanding of important processes in engineered and natural systems. In this study, changes in local electromagnetic environments of the carbon atoms in methane under conditions of high pressure (up to 130 bar) and moderate temperature (up to 346 K) were observed with 13C magic-angle spinning (MAS) NMR spectroscopy while the methane gas was mixed with two model solid substrates: a fumed non-porous, 12 nm particle size silica and a mesoporous silica with 200 nm particle size and 4 nm average pore diameter. Examination of the interactions between methane and the silica systems over temperatures and pressures that include the supercritical regime was allowed by a novel high pressure MAS sample containment system, which provided high resolution spectra collected under in situ conditions. For pure methane, no significant thermal effects were found for the observed 13C chemical shifts at all pressures studied here (28.2 bar, 32.6 bar, 56.4 bar, 65.1 bar, 112.7 bar, and 130.3 bar). However, the 13C chemical shifts of resonances arising from confined methane changed slightly with changes in temperature in mixtures with mesoporous silica. The chemical shift values of 13C nuclides in methane change measurably as a function of pressure both in the pure state and in mixtures with both silica matrices, with a more pronounced shift when meso-porous silica is present. Molecular-level simulations utilizing GCMC, MD and DFT confirm qualitatively that the experimentally measured changes are attributed to interactions of methane with the hydroxylated silica surfaces as well as densification of methane within nanopores and on pore surfaces.

  7. Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study

    International Nuclear Information System (INIS)

    Ok, Salim; Hoyt, David W.; Andersen, Amity; Sheets, Julie; Welch, Susan A.

    2017-01-01

    Characterization and modeling of the molecular-level behavior of simple hydrocarbon gases, such as methane, in the presence of both nonporous and nanoporous mineral matrices allows for predictive understanding of important processes in engineered and natural systems. In this study, we observed changes in local electromagnetic environments of the carbon atoms in methane under conditions of high pressure (up to 130 bar) and moderate temperature (up to 346 K) with 13 C magic-angle spinning (MAS) NMR spectroscopy while the methane gas was mixed with two model solid substrates: a fumed nonporous, 12 nm particle size silica and a mesoporous silica with 200 nm particle size and 4 nm average pore diameter. Examination of the interactions between methane and the silica systems over temperatures and pressures that include the supercritical regime was allowed by a novel high pressure MAS sample containment system, which provided high resolution spectra collected under in situ conditions. There was no significant thermal effects were found for the observed 13 C chemical shifts at all pressures studied here (28.2, 32.6, 56.4, 65.1, 112.7, and 130.3 bar) for pure methane. However, the 13 C chemical shifts of resonances arising from confined methane changed slightly with changes in temperature in mixtures with mesoporous silica. The chemical shift values of 13 C nuclides in methane change measurably as a function of pressure both in the pure state and in mixtures with both silica matrices, with a more pronounced shift when meso-porous silica is present. Molecular-level simulations utilizing GCMC, MD, and DFT confirm qualitatively that the experimentally measured changes are attributed to interactions of methane with the hydroxylated silica surfaces as well as densification of methane within nanopores and on pore surfaces.

  8. Screening Mixtures of Small Molecules for Binding to Multiple Sites on the Surface Tetanus Toxin C Fragment by Bioaffinity NMR

    Energy Technology Data Exchange (ETDEWEB)

    Cosman, M; Zeller, L; Lightstone, F C; Krishnan, V V; Balhorn, R

    2002-01-01

    The clostridial neurotoxins include the closely related tetanus (TeNT) and botulinum (BoNT) toxins. Botulinum toxin is used to treat severe muscle disorders and as a cosmetic wrinkle reducer. Large quantities of botulinum toxin have also been produced by terrorists for use as a biological weapon. Because there are no known antidotes for these toxins, they thus pose a potential threat to human health whether by an accidental overdose or by a hostile deployment. Thus, the discovery of high specificity and affinity compounds that can inhibit their binding to neural cells can be used as antidotes or in the design of chemical detectors. Using the crystal structure of the C fragment of the tetanus toxin (TetC), which is the cell recognition and cell surface binding domain, and the computational program DOCK, sets of small molecules have been predicted to bind to two different sites located on the surface of this protein. While Site-1 is common to the TeNT and BoNTs, Site-2 is unique to TeNT. Pairs of these molecules from each site can then be linked together synthetically to thereby increase the specificity and affinity for this toxin. Electrospray ionization mass spectroscopy was used to experimentally screen each compound for binding. Mixtures containing binders were further screened for activity under biologically relevant conditions using nuclear magnetic resonance (NMR) methods. The screening of mixtures of compounds offers increased efficiency and throughput as compared to testing single compounds and can also evaluate how possible structural changes induced by the binding of one ligand can influence the binding of the second ligand. In addition, competitive binding experiments with mixtures containing ligands predicted to bind the same site could identify the best binder for that site. NMR transfer nuclear Overhauser effect (trNOE) confirm that TetC binds doxorubicin but that this molecule is displaced by N-acetylneuraminic acid (sialic acid) in a mixture that

  9. Screening Mixtures of Small Molecules for Binding to Multiple Sites on the Surface Tetanus Toxin C Fragment by Bioaffinity NMR

    International Nuclear Information System (INIS)

    Cosman, M; Zeller, L; Lightstone, F C; Krishnan, V V; Balhorn, R

    2002-01-01

    The clostridial neurotoxins include the closely related tetanus (TeNT) and botulinum (BoNT) toxins. Botulinum toxin is used to treat severe muscle disorders and as a cosmetic wrinkle reducer. Large quantities of botulinum toxin have also been produced by terrorists for use as a biological weapon. Because there are no known antidotes for these toxins, they thus pose a potential threat to human health whether by an accidental overdose or by a hostile deployment. Thus, the discovery of high specificity and affinity compounds that can inhibit their binding to neural cells can be used as antidotes or in the design of chemical detectors. Using the crystal structure of the C fragment of the tetanus toxin (TetC), which is the cell recognition and cell surface binding domain, and the computational program DOCK, sets of small molecules have been predicted to bind to two different sites located on the surface of this protein. While Site-1 is common to the TeNT and BoNTs, Site-2 is unique to TeNT. Pairs of these molecules from each site can then be linked together synthetically to thereby increase the specificity and affinity for this toxin. Electrospray ionization mass spectroscopy was used to experimentally screen each compound for binding. Mixtures containing binders were further screened for activity under biologically relevant conditions using nuclear magnetic resonance (NMR) methods. The screening of mixtures of compounds offers increased efficiency and throughput as compared to testing single compounds and can also evaluate how possible structural changes induced by the binding of one ligand can influence the binding of the second ligand. In addition, competitive binding experiments with mixtures containing ligands predicted to bind the same site could identify the best binder for that site. NMR transfer nuclear Overhauser effect (trNOE) confirm that TetC binds doxorubicin but that this molecule is displaced by N-acetylneuraminic acid (sialic acid) in a mixture that

  10. Specific binding of a naturally occurring amyloidogenic fragment of Streptococcus mutans adhesin P1 to intact P1 on the cell surface characterized by solid state NMR spectroscopy.

    Science.gov (United States)

    Tang, Wenxing; Bhatt, Avni; Smith, Adam N; Crowley, Paula J; Brady, L Jeannine; Long, Joanna R

    2016-02-01

    The P1 adhesin (aka Antigen I/II or PAc) of the cariogenic bacterium Streptococcus mutans is a cell surface-localized protein involved in sucrose-independent adhesion and colonization of the tooth surface. The immunoreactive and adhesive properties of S. mutans suggest an unusual functional quaternary ultrastructure comprised of intact P1 covalently attached to the cell wall and interacting with non-covalently associated proteolytic fragments thereof, particularly the ~57-kDa C-terminal fragment C123 previously identified as Antigen II. S. mutans is capable of amyloid formation when grown in a biofilm and P1 is among its amyloidogenic proteins. The C123 fragment of P1 readily forms amyloid fibers in vitro suggesting it may play a role in the formation of functional amyloid during biofilm development. Using wild-type and P1-deficient strains of S. mutans, we demonstrate that solid state NMR (ssNMR) spectroscopy can be used to (1) globally characterize cell walls isolated from a Gram-positive bacterium and (2) characterize the specific binding of heterologously expressed, isotopically-enriched C123 to cell wall-anchored P1. Our results lay the groundwork for future high-resolution characterization of the C123/P1 ultrastructure and subsequent steps in biofilm formation via ssNMR spectroscopy, and they support an emerging model of S. mutans colonization whereby quaternary P1-C123 interactions confer adhesive properties important to binding to immobilized human salivary agglutinin.

  11. Specific binding of a naturally occurring amyloidogenic fragment of Streptococcus mutans adhesin P1 to intact P1 on the cell surface characterized by solid state NMR spectroscopy

    International Nuclear Information System (INIS)

    Tang, Wenxing; Bhatt, Avni; Smith, Adam N.; Crowley, Paula J.; Brady, L. Jeannine; Long, Joanna R.

    2016-01-01

    The P1 adhesin (aka Antigen I/II or PAc) of the cariogenic bacterium Streptococcus mutans is a cell surface-localized protein involved in sucrose-independent adhesion and colonization of the tooth surface. The immunoreactive and adhesive properties of S. mutans suggest an unusual functional quaternary ultrastructure comprised of intact P1 covalently attached to the cell wall and interacting with non-covalently associated proteolytic fragments thereof, particularly the ∼57-kDa C-terminal fragment C123 previously identified as Antigen II. S. mutans is capable of amyloid formation when grown in a biofilm and P1 is among its amyloidogenic proteins. The C123 fragment of P1 readily forms amyloid fibers in vitro suggesting it may play a role in the formation of functional amyloid during biofilm development. Using wild-type and P1-deficient strains of S. mutans, we demonstrate that solid state NMR (ssNMR) spectroscopy can be used to (1) globally characterize cell walls isolated from a Gram-positive bacterium and (2) characterize the specific binding of heterologously expressed, isotopically-enriched C123 to cell wall-anchored P1. Our results lay the groundwork for future high-resolution characterization of the C123/P1 ultrastructure and subsequent steps in biofilm formation via ssNMR spectroscopy, and they support an emerging model of S. mutans colonization whereby quaternary P1-C123 interactions confer adhesive properties important to binding to immobilized human salivary agglutinin

  12. Specific binding of a naturally occurring amyloidogenic fragment of Streptococcus mutans adhesin P1 to intact P1 on the cell surface characterized by solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Wenxing; Bhatt, Avni [University of Florida, Department of Biochemistry and Molecular Biology, College of Medicine (United States); Smith, Adam N. [University of Florida, Department of Chemistry, College of Liberal Arts and Sciences (United States); Crowley, Paula J.; Brady, L. Jeannine, E-mail: jbrady@dental.ufl.edu [University of Florida, Department of Oral Biology, College of Dentistry (United States); Long, Joanna R., E-mail: jrlong@ufl.edu [University of Florida, Department of Biochemistry and Molecular Biology, College of Medicine (United States)

    2016-02-15

    The P1 adhesin (aka Antigen I/II or PAc) of the cariogenic bacterium Streptococcus mutans is a cell surface-localized protein involved in sucrose-independent adhesion and colonization of the tooth surface. The immunoreactive and adhesive properties of S. mutans suggest an unusual functional quaternary ultrastructure comprised of intact P1 covalently attached to the cell wall and interacting with non-covalently associated proteolytic fragments thereof, particularly the ∼57-kDa C-terminal fragment C123 previously identified as Antigen II. S. mutans is capable of amyloid formation when grown in a biofilm and P1 is among its amyloidogenic proteins. The C123 fragment of P1 readily forms amyloid fibers in vitro suggesting it may play a role in the formation of functional amyloid during biofilm development. Using wild-type and P1-deficient strains of S. mutans, we demonstrate that solid state NMR (ssNMR) spectroscopy can be used to (1) globally characterize cell walls isolated from a Gram-positive bacterium and (2) characterize the specific binding of heterologously expressed, isotopically-enriched C123 to cell wall-anchored P1. Our results lay the groundwork for future high-resolution characterization of the C123/P1 ultrastructure and subsequent steps in biofilm formation via ssNMR spectroscopy, and they support an emerging model of S. mutans colonization whereby quaternary P1-C123 interactions confer adhesive properties important to binding to immobilized human salivary agglutinin.

  13. Determination of solid fat content by NMR

    International Nuclear Information System (INIS)

    Kawada, Tsukasa; Kato, Chihiro; Suzuki, Kazuaki

    1984-01-01

    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)

  14. Exploring inclusion complexes of ionic liquids with α- and β- cyclodextrin by NMR, IR, mass, density, viscosity, surface tension and conductance study

    Science.gov (United States)

    Barman, Biraj Kumar; Rajbanshi, Biplab; Yasmin, Ananya; Roy, Mahendra Nath

    2018-05-01

    The formation of the host-guest inclusion complexes of ionic liquids namely [BMIm]Cl and [HMIm]Cl with α-CD and β-CD were studied by means of physicochemical and spectroscopic methods. Conductivity and surface tension study were in good agreement with the 1H NMR and FT-IR studies which confirm the formation of the inclusion complexes. The Density and viscosity study also supported the formation of the ICs. Further the stoichiometry was determined 1:1 for each case and the association constants and thermodynamic parameters derived supported the most feasible formation of the [BMIm]Cl- β-CD inclusion complex.

  15. $^{11}$B and $^{27}$Al NMR spin-lattice relaxation and Knight shift study of Mg$_{1-x}$Al$_x$B$_2$. Evidence for anisotropic Fermi surface

    OpenAIRE

    Papavassiliou, G.; Pissas, M.; Karayanni, M.; Fardis, M.; Koutandos, S.; Prassides, K.

    2002-01-01

    We report a detailed study of $^{11}$B and $^{27}$Al NMR spin-lattice relaxation rates ($1/T_1$), as well as of $^{27}$Al Knight shift (K) of Mg$_{1-x}$Al$_x$B$_2$, $0\\leq x\\leq 1$. The obtained ($1/T_1T$) and K vs. x plots are in excellent agreement with ab initio calculations. This asserts experimentally the prediction that the Fermi surface is highly anisotropic, consisting mainly of hole-type 2-D cylindrical sheets from bonding $2p_{x,y}$ boron orbitals. It is also shown that the density ...

  16. O-17 NMR measurement of water

    International Nuclear Information System (INIS)

    Fukazawa, Nobuyuki

    1990-01-01

    Recently, attention has been paid to the various treatment of water and the utilization of water by magnetic treatment, electric field treatment and so on. It has been said that by these treatments, the change in the properties of water arises. The state of this treated water cannot be explained by the properties of water from conventional physical and chemical standpoints. In addition, the method of measurement of whether the change arose or not is not yet determined. It is necessary to establish the method of measurement for the basic state of water. In this study, O-17 NMR which observes the state of water directly at molecular or atomic level was investigated as the method of measuring water. The measurement of O-17 NMR was carried out with a JNR 90Q FT NMR of Fourier transformation type of JEOL Ltd. The experimental method and the results are reported. The result of measurement of the O-17 NMR spectrum for distilled ion exchange water is shown. It is know that it has very wide line width as compared with the NMR spectra of protons and C-13. The relative sensitivity of O-17 observation is about 1/100,000 of that of protons. As to the information on the state of water obtained by O-17 NMR, there are chemical shift and line width. As temperature rose, the line width showed decrease, which seemed to be related to the decrease of hydrogen combination. (K.I.)

  17. Optical pumping and xenon NMR

    International Nuclear Information System (INIS)

    Raftery, M.D.

    1991-11-01

    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 129 Xe 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 131 Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen

  18. NMR identification of the binding surfaces involved in the Salmonella and Shigella Type III secretion tip-translocon protein-protein interactions.

    Science.gov (United States)

    McShan, Andrew C; Kaur, Kawaljit; Chatterjee, Srirupa; Knight, Kevin M; De Guzman, Roberto N

    2016-08-01

    The type III secretion system (T3SS) is essential for the pathogenesis of many bacteria including Salmonella and Shigella, which together are responsible for millions of deaths worldwide each year. The structural component of the T3SS consists of the needle apparatus, which is assembled in part by the protein-protein interaction between the tip and the translocon. The atomic detail of the interaction between the tip and the translocon proteins is currently unknown. Here, we used NMR methods to identify that the N-terminal domain of the Salmonella SipB translocon protein interacts with the SipD tip protein at a surface at the distal region of the tip formed by the mixed α/β domain and a portion of its coiled-coil domain. Likewise, the Shigella IpaB translocon protein and the IpaD tip protein interact with each other using similar surfaces identified for the Salmonella homologs. Furthermore, removal of the extreme N-terminal residues of the translocon protein, previously thought to be important for the interaction, had little change on the binding surface. Finally, mutations at the binding surface of SipD reduced invasion of Salmonella into human intestinal epithelial cells. Together, these results reveal the binding surfaces involved in the tip-translocon protein-protein interaction and advance our understanding of the assembly of the T3SS needle apparatus. Proteins 2016; 84:1097-1107. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Magnetic-Field Effects on the Size of Vortices below the Surface of NbSe2 Detected Using Low Energy β-NMR

    Science.gov (United States)

    Salman, Z.; Wang, D.; Chow, K. H.; Hossain, M. D.; Kreitzman, S. R.; Keeler, T. A.; Levy, C. D. P.; Macfarlane, W. A.; Miller, R. I.; Morris, G. D.; Parolin, T. J.; Saadaoui, H.; Smadella, M.; Kiefl, R. F.

    2007-04-01

    A low energy radioactive beam of polarized Li8 has been used to observe the vortex lattice near the surface of superconducting NbSe2. The inhomogeneous magnetic-field distribution associated with the vortex lattice was measured using depth-resolved β-detected NMR. Below Tc, one observes the characteristic line shape for a triangular vortex lattice which depends on the magnetic penetration depth and vortex core radius. The size of the vortex core varies strongly with the magnetic field. In particular, in a low field of 10.8 mT, the core radius is much larger than the coherence length. The possible origin of these giant vortices is discussed.

  20. Magnetic-field effects on the size of vortices below the surface of NbSe2 detected using low energy beta-NMR.

    Science.gov (United States)

    Salman, Z; Wang, D; Chow, K H; Hossain, M D; Kreitzman, S R; Keeler, T A; Levy, C D P; MacFarlane, W A; Miller, R I; Morris, G D; Parolin, T J; Saadaoui, H; Smadella, M; Kiefl, R F

    2007-04-20

    A low energy radioactive beam of polarized 8Li has been used to observe the vortex lattice near the surface of superconducting NbSe2. The inhomogeneous magnetic-field distribution associated with the vortex lattice was measured using depth-resolved beta-detected NMR. Below Tc, one observes the characteristic line shape for a triangular vortex lattice which depends on the magnetic penetration depth and vortex core radius. The size of the vortex core varies strongly with the magnetic field. In particular, in a low field of 10.8 mT, the core radius is much larger than the coherence length. The possible origin of these giant vortices is discussed.

  1. Nuclear magnetic relaxation dispersion and 31P-NMR studies of the effect of covalent modification of membrane surfaces with poly(ethylene glycol).

    Science.gov (United States)

    Tilcock, C; Ahkong, Q F; Koenig, S H; Brown, R D; Kabalka, G; Fisher, D

    1992-10-05

    Covalent attachment of methoxypoly(ethylene glycol) (MPEG) 5000 to the surface of unilamellar liposomes composed of egg phosphatidylcholine and dioleoylphosphatidylethanolamine (DOPE) (8:2) containing paramagnetic chelates, either entrapped within the interior volume of the liposomes, or associated with the membrane surface, had no effect upon the measured spin-lattice relaxation rates (1/T1) for water in these systems. 31P-NMR studies indicate no destabilization of dioleoylphosphatidylcholine (DOPC)/(DOPE) (1:1) vesicles following attachment of MPEG. However, in DOPC/DOPE (1:3) mixtures, covalent modification with MPEG results in a destabilization of multilamellar vesicles into smaller vesicular structures. These results indicate that covalent attachment of poly(ethylene glycol) to liposomal magnetic resonance agents may prove a useful method for increasing their utility as vascular MR agents by extending their lifetime in the circulation, without decreasing the relaxivity of paramagnetic species associated with the liposome, but that the presence of PEG covalently attached to the membrane surface may modify the polymorphic phase behavior of the lipid system to which it is covalently linked.

  2. Tungsten(VI) Carbyne/Bis(carbene) Tautomerization Enabled by N-Donor SBA15 Surface Ligands: A Solid-State NMR and DFT Study

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa

    2016-08-11

    Designing supported well-defined bis(carbene) complexes remains a key challenge in heterogeneous catalysis. The reaction of W(CtBu)(CH(2)tBu)(3) with amine-modified mesoporous SBA15 silica, which has vicinal silanol/silylamine pairs [(SiOH)(SiNH2)], leads to [(SiNH2-)(SiO-)W(CHtBu)(CH(2)tBu)(2)] and [(SiNH2-)(SiO-)W(=CHtBu)(2)(CH(2)tBu). Variable temperature, H-1-H-1 2D double-quantum, H-1-C-13 HETCOR, and HETCOR with spin diffusion solid-state NMR spectroscopy demonstrate tautomerization between the alkyl alkylidyne and the bis(alkylidene) on the SBA15 surface. Such equilibrium is possible through the coordination of W to the surface [(Si-OH)(Si-NH2)] groups, which act as a [N,O] pincer ligand. DFT calculations provide a rationalization for the surface-complex tautomerization and support the experimental results. This direct observation of such a process shows the strong similarity between molecular mechanisms in homogeneous and heterogeneous catalysis. In propane metathesis (at 150 degrees C), the tungsten bis(carbene) tautomer is favorable, with a turnover number (TON) of 262. It is the highest TON among all the tungsten alkyl-supported catalysts.

  3. Nature and structure of aluminum surface sites grafted on silica from a combination of high-field aluminum-27 solid-state NMR spectroscopy and first-principles calculations

    KAUST Repository

    Kerber, Rachel Nathaniel

    2012-04-18

    The determination of the nature and structure of surface sites after chemical modification of large surface area oxides such as silica is a key point for many applications and challenging from a spectroscopic point of view. This has been, for instance, a long-standing problem for silica reacted with alkylaluminum compounds, a system typically studied as a model for a supported methylaluminoxane and aluminum cocatalyst. While 27Al solid-state NMR spectroscopy would be a method of choice, it has been difficult to apply this technique because of large quadrupolar broadenings. Here, from a combined use of the highest stable field NMR instruments (17.6, 20.0, and 23.5 T) and ultrafast magic angle spinning (>60 kHz), high-quality spectra were obtained, allowing isotropic chemical shifts, quadrupolar couplings, and asymmetric parameters to be extracted. Combined with first-principles calculations, these NMR signatures were then assigned to actual structures of surface aluminum sites. For silica (here SBA-15) reacted with triethylaluminum, the surface sites are in fact mainly dinuclear Al species, grafted on the silica surface via either two terminal or two bridging siloxy ligands. Tetrahedral sites, resulting from the incorporation of Al inside the silica matrix, are also seen as minor species. No evidence for putative tri-coordinated Al atoms has been found. © 2012 American Chemical Society.

  4. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sørland, 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 background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

  5. Resolving three-dimensional shape of sub-50 nm wide lines with nanometer-scale sensitivity using conventional optical microscopes

    International Nuclear Information System (INIS)

    Attota, Ravikiran; Dixson, Ronald G.

    2014-01-01

    We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

  6. NMR of lignins

    Science.gov (United States)

    John Ralph; Larry L. Landucci

    2010-01-01

    This chapter will consider the basic aspects and findings of several forms of NMR spectroscopy, including separate discussions of proton, carbon, heteronuclear, and multidimensional NMR. Enhanced focus will be on 13C NMR, because of its qualitative and quantitative importance, followed by NMR’s contributions to our understanding of lignin...

  7. Surface characteristics of the iron-oxyhydroxide layer formed during brick coatings by ESEM/EDS, {sup 23}Na and {sup 1}H MAS NMR, and ToF-SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Allahdin, O. [Chaire Unesco « Sur la gestion de l' eau », Laboratoire Hydrosciences Lavoisier, Université de Bangui, Faculté des Sciences, B.P. 908 (Central African Republic); Wartel, M. [Université Lille1, Laboratoire LASIR (UMR CNRS 8516), Equipe Physico-chimie de l' Environnement, Bât. C8, 2" è" m" e étage, 59655 Villeneuve d' Ascq cedex (France); Mabingui, J. [Chaire Unesco « Sur la gestion de l' eau », Laboratoire Hydrosciences Lavoisier, Université de Bangui, Faculté des Sciences, B.P. 908 (Central African Republic); Revel, B. [Université Lille1, Service RMN, Bât. C4, 59655 Villeneuve d' Ascq cedex (France); Nuns, N. [Université Lille1, Institut Chevreul, 59655 Villeneuve d' Ascq cedex (France); Boughriet, A., E-mail: abdel.boughriet@univ-lille1.fr [Université Lille1, Laboratoire LASIR (UMR CNRS 8516), Equipe Physico-chimie de l' Environnement, Bât. C8, 2" è" m" e étage, 59655 Villeneuve d' Ascq cedex (France)

    2015-09-01

    Brick made locally by craftsmen in Bangui (Central African Republic) was modified first by HCl activation and second by iron-oxyhydroxide impregnation through the precipitation of ferric ions by NaOH at various fixed pH values (ranging from 3 to 13). The elemental analyses of synthesized compounds were performed using ICP-AES, and their surface chemistry/properties were investigated by environmental scanning electron microscopy (ESEM/EDS), {sup 1}H and {sup 23}Na MAS NMR spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The evidence of different {sup 23}Na chemical environments and the coexistence of Si and Al bound to ferrihydrite were made. The surface properties of this material which was found to be dependent upon synthesis pH, contributed to enhance metal uptake from water. - Highlights: • HCl-activated brick was coated at different Fe(III)-precipitation pH. • Surface properties were determined by ESEM, NMR and ToF-SIMS. • Al- and Si-bearing ferrihydrite and different Na environments were detected. • The pH used for modified-brick synthesis influenced metal uptake from water.

  8. NMR-spectroscopy

    International Nuclear Information System (INIS)

    Lundin, A.G.; Fedin, Eh.I.

    1986-01-01

    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

  9. Reversible binding of the HPLC6 isoform of type I antifreeze proteins to ice surfaces and the antifreeze mechanism studied by multiple quantum filtering-spin exchange NMR experiment.

    Science.gov (United States)

    Ba, Yong; Wongskhaluang, Jeff; Li, Jiabo

    2003-01-15

    Antifreeze proteins (AFPs) protect organisms from freezing damage by inhibiting the growth of seed-ice crystals. It has long been hypothesized that irreversible binding of AFPs to ice surfaces is responsible for inhibiting the growth of seed-ice crystals as such a mechanism supports the popularly accepted Kelvin effect for the explanation of local freezing-point depression. However, whether the binding is reversible or irreversible is still under debate due to the lack of direct experimental evidence. Here, we report the first direct experimental result, by using the newly developed multiple quantum (MQ) filtering-spin exchange NMR experiment, that shows that the binding of HPLC6 peptides to ice surfaces is reversible. It was found that the reversible process can be explained by the model of monolayer adsorption. These results suggest that the Kelvin effect is not suitable for explaining the antifreeze mechanism, and direct interactions between the peptides and the ice-surface binding sites are the driving forces for the binding of AFPs to ice surfaces. We propose that there exists a concentration gradient of AFP from an ice-binding surface to the solution due to the affinity of ice surfaces to AFPs. This concentration gradient creates a dense layer of AFP in contact with the ice-binding surface, which depresses the local freezing point because of the colligative property, but not the Kelvin effect.

  10. From single-site tantalum complexes to nanoparticles of TaxNy and TaOxNy supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy

    KAUST Repository

    Mohandas, Janet Chakkamadathil

    2017-06-08

    Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of TaxNy and TaOxNy with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe5 (Me = methyl) and dimeric Ta-2(OMe)(10) with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of H-1, C-13, Si-29, and N-15 at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O-2 insertion into Ta-CH3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta-2(OMe)(10) on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H2O2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as TaxNy/TaOxNy.

  11. Structural changes of humic acids from sinking organic matter and surface sediments investigated by advanced solid-state NMR: Insights into sources, preservation and molecularly uncharacterized components

    Science.gov (United States)

    Mao, Jingdong; Tremblay, Luc; Gagné, Jean-Pierre

    2011-12-01

    Knowledge of the structural changes that particulate organic matter (POM) undergoes in natural systems is essential for determining its reactivity and fate. In the present study, we used advanced solid-state NMR techniques to investigate the chemical structures of sinking particulate matter collected at different depths as well as humic acids (HAs) extracted from these samples and underlying sediments from the Saguenay Fjord and the St. Lawrence Lower Estuary (Canada). Compared to bulk POM, HAs contain more non-polar alkyls, aromatics, and aromatic C-O, but less carbohydrates (or carbohydrate-like structures). In the two locations studied, the C and N contents of the samples (POM and HAs) decreased with depth and after deposition onto sediments, leaving N-poor but O-enriched HAs and suggesting the involvement of partial oxidation reactions during POM microbial degradation. Advanced NMR techniques revealed that, compared to the water-column HAs, sedimentary HAs contained more protonated aromatics, non-protonated aromatics, aromatic C-O, carbohydrates (excluding anomerics), anomerics, OC q, O-C q-O, OCH, and OCH 3 groups, but less non-polar alkyls, NCH, and mobile CH 2 groups. These results are consistent with the relatively high reactivity of lipids and proteins or peptides. In contrast, carbohydrate-like structures were selectively preserved and appeared to be involved in substitution and copolymerization reactions. Some of these trends support the selective degradation (or selective preservation) theory. The results provide insights into mechanisms that likely contribute to the preservation of POM and the formation of molecules that escape characterization by traditional methods. Despite the depletion of non-polar alkyls with depth in HAs, a significant portion of their general structure survived and can be assigned to a model phospholipid. In addition, little changes in the connectivities of different functional groups were observed. Substituted and copolymerized

  12. Effects of specific surface area and porosity on cube counting fractal dimension, lacunarity, configurational entropy, and permeability of model porous networks: Random packing simulations and NMR micro-imaging study

    Science.gov (United States)

    Lee, Bum Han; Lee, Sung Keun

    2013-07-01

    Despite the importance of understanding and quantifying the microstructure of porous networks in diverse geologic settings, the effects of the specific surface area and porosity on the key structural parameters of the networks have not been fully understood. We performed cube-counting fractal dimension (Dcc) and lacunarity analyses of 3D porous networks of model sands and configurational entropy analysis of 2D cross sections of model sands using random packing simulations and nuclear magnetic resonance (NMR) micro-imaging. We established relationships among porosity, specific surface area, structural parameters (Dcc and lacunarity), and the corresponding macroscopic properties (configurational entropy and permeability). The Dcc of the 3D porous networks increases with increasing specific surface area at a constant porosity and with increasing porosity at a constant specific surface area. Predictive relationships correlating Dcc, specific surface area, and porosity were also obtained. The lacunarity at the minimum box size decreases with increasing porosity, and that at the intermediate box size (∼0.469 mm in the current model sands) was reproduced well with specific surface area. The maximum configurational entropy increases with increasing porosity, and the entropy length of the pores decreases with increasing specific surface area and was used to calculate the average connectivity among the pores. The correlation among porosity, specific surface area, and permeability is consistent with the prediction from the Kozeny-Carman equation. From the relationship between the permeability and the Dcc of pores, the permeability can be expressed as a function of the Dcc of pores and porosity. The current methods and these newly identified correlations among structural parameters and properties provide improved insights into the nature of porous media and have useful geophysical and hydrological implications for elasticity and shear viscosity of complex composites of rock

  13. Functional studies using NMR

    International Nuclear Information System (INIS)

    McCready, V.R.; Leach, M.O.; Sutton; Ell, P.

    1986-01-01

    The object of this book is to discuss and evaluate an area of Nuclear Magnetic Resonance which to date has been less emphasized than it might be, namely the use of NMR for functional studies. The book commences with a discussion of the areas in which the NMR techniques might be needed due to deficiencies in other techniques. The physics of NMR especially relating to functional measurement are then explained. Technical factors in producing functional images are discussed and the use of paramagnetic substances for carrying out flow studies are detailed. Particular attention is paid to specific studies in the various organs. The book ends with a survey of imaging in each organ and the relation of NMR images to other techniques such as ultrasound, nuclear medicine and X-rays

  14. Functional studies using NMR

    International Nuclear Information System (INIS)

    McCready, V.R.; Leach, M.; Ell, P.J.

    1987-01-01

    This volume is based on a series of lectures delivered at a one-day teaching symposium on functional and metabolic aspects of NMR measurements held at the Middlesex Hospital Medical School on 1st September 1985 as a part of the European Nuclear Medicine Society Congress. Currently the major emphasis in medical NMR in vivo is on its potential to image and display abnormalities in conventional radiological images, providing increased contrast between normal and abnormal tissue, improved definition of vasculature, and possibly an increased potential for differential diagnosis. Although these areas are undeniably of major importance, it is probable that NMR will continue to complement conventional measurement methods. The major potential benefits to be derived from in vivo NMR measurements are likely to arise from its use as an instrument for functional and metabolic studies in both clinical research and in the everyday management of patients. It is to this area that this volume is directed

  15. UC Merced NMR Instrumentation Acquisition

    Science.gov (United States)

    2015-06-18

    UC Merced NMR Instrumentation Acquisition For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500 MHz NMR...valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. University of California - Merced 5200 North Lake Road Merced , CA 95343...UC Merced NMR Instrumentation Acquisition Report Title For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500

  16. The Effect of Solvent Accessible Surface on Hammett-Type Dependencies of Infinite Dilution 29Si and 13C NMR Shifts in Ring Substituted Silylated Phenols Dissolved in Chloroform and Acetone

    Czech Academy of Sciences Publication Activity Database

    Blechta, Vratislav; Šabata, Stanislav; Sýkora, Jan; Hetflejš, Jiří; Soukupová, Ludmila; Schraml, Jan

    2012-01-01

    Roč. 50, č. 2 (2012), s. 128-134 ISSN 0749-1581 R&D Projects: GA AV ČR IAA400720706; GA ČR GA203/06/0738 Institutional research plan: CEZ:AV0Z40720504 Keywords : 1H NMR * 13C NMR * 29Si NMR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.528, year: 2012

  17. 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.

  18. Microprocessorized NMR measurement

    International Nuclear Information System (INIS)

    Rijllart, A.

    1984-01-01

    An MC68000 CAMAC microprocessor system for fast and accurate NMR signal measurement will be presented. A stand-alone CAMAC microprocessor system (MC68000 STAC) with a special purpose interface sweeps a digital frequency synthesizer and digitizes the NMR signal with a 16-bit ADC of 17 μs conversion time. It averages the NMR signal data over many sweeps and then transfers it through CAMAC to a computer for calculation of the signal parameters. The computer has full software control over the timing and sweep settings of this signal averager, and thus allows optimization of noise suppression. Several of these processor systems can be installed in the same crate for parallel processing, and the flexibility of the STAC also allows easy adaptation to other applications such as transient recording or phase-sensitive detection. (orig.)

  19. Structural NMR assignment

    International Nuclear Information System (INIS)

    Procter, J.B.; Torda, A.E.

    1999-01-01

    Full text: General automated NMR assignment approaches are aimed at full heteronuclear assignment, which is needed for structure determination. Usually, full assignment requires at least as much spectral information as is used for structure generation. For large proteins, obtaining sufficient spectral information may require a number of sample preparations and many spectra, resulting in a significant overhead for the use of NMR in biochemical investigation. For a protein of biochemical interest one may already have an x-ray crystal structure, but spectral assignment is still needed to use NMR as a structural probe for ligand binding studies. In this situation it may be possible to use much less spectral information to make an assignment based purely on the correspondence of structural data to the measurements contained in a few simple spectra. We introduce a framework to accomplish this 'structural assignment', and give some observations on the practical requirements for a structural assignment to succeed

  20. 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.)

  1. Autonomous driving in NMR.

    Science.gov (United States)

    Perez, Manuel

    2017-01-01

    The automatic analysis of NMR data has been a much-desired endeavour for the last six decades, as it is the case with any other analytical technique. This need for automation has only grown as advances in hardware; pulse sequences and automation have opened new research areas to NMR and increased the throughput of data. Full automatic analysis is a worthy, albeit hard, challenge, but in a world of artificial intelligence, instant communication and big data, it seems that this particular fight is happening with only one technique at a time (let this be NMR, MS, IR, UV or any other), when the reality of most laboratories is that there are several types of analytical instrumentation present. Data aggregation, verification and elucidation by using complementary techniques (e.g. MS and NMR) is a desirable outcome to pursue, although a time-consuming one if performed manually; hence, the use of automation to perform the heavy lifting for users is required to make the approach attractive for scientists. Many of the decisions and workflows that could be implemented under automation will depend on the two-way communication with databases that understand analytical data, because it is desirable not only to query these databases but also to grow them in as much of an automatic manner as possible. How these databases are designed, set up and the data inside classified will determine what workflows can be implemented. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  2. NMR, water and plants

    NARCIS (Netherlands)

    As, van H.

    1982-01-01

    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

  3. NMR of unfolded proteins

    Indian Academy of Sciences (India)

    Unknown

    2005-01-03

    Jan 3, 2005 ... out' response to environmental changes with structural complexity ... of 3D structure at atomic resolution of folded proteins ...... 5.14 HIV-1 protease. NMR identification of local structural preferences in. HIV-1 protease in the 'unfolded state' at 6 M gua- nidine hydrochloride has been reported.49 Analyses.

  4. Single-sided NMR

    CERN Document Server

    Casanova, Federico; Blümich, Bernhard

    2011-01-01

    Single-Sided NMR describes the design of the first functioning single-sided tomograph, the related measurement methods, and a number of applications. One of the key advantages to this method is the speed at which the images are obtained.

  5. NMR for chemists and biologists

    CERN Document Server

    Carbajo, Rodrigo J

    2013-01-01

    This book offers a concise introduction to the field of nuclear magnetic resonance or NMR. It presents the basic foundations of NMR in a non-mathematical way and provides an overview of both recent and important biological applications of NMR.

  6. A Hirshfeld surface analysis, crystal and geometry-optimized structure, and solid state NMR studies of two novel α-hydroxyphosphonates C17H21O4P (I) and C19H25O4P(II)

    Science.gov (United States)

    Essid, Idris; Soudani, Sarra; Lefebvre, Frédéric; Kaminsky, Werner; Fujita, Wataru; Ben Nasr, Cherif; Touil, Soufiane

    2017-12-01

    We report efficient and green syntheses of two α-hydroxyphosphonates, C17H21O4P (I) and C19H25O4P (II), obtained by the reaction of dialkylphosphites with 1,3-diphenylacetone, on magnesia support, under solvent-free conditions. Their structures were determined by single crystal X-ray diffraction. Compound (I) crystallizes in the monoclinic system and P21/c space group with a = 10.2656(4), b = 7.0539(3), c = 23.3340(1) Å, β = 100.514(2)°, V = 1661.72(12) Å3 with Z = 4. The structure was refined to R = 0.044, wR(F2) = 0.101. Compound (II) belongs also to the monoclinic system, space group P21/c with the following parameters: a = 11.8110 (13), b = 16.0285 (17), c = 10.0691 (12) Å, β = 103.254(3)°, V = 1855.4 (4)Å3 and Z = 4. The structure was refined to R = 0.061, wR(F2) = 0.173. The molecular properties of these two compounds were characterized by multinuclear solid state (13C and 31P) CP-MAS-NMR. Intermolecular interactions were investigated by Hirshfeld surfaces. Electronic properties such as HOMO and LUMO energies were derived.

  7. Morphology and side-chain dynamics in hydrated hard α-keratin fibres by 1H solid-state NMR

    Science.gov (United States)

    Melian, Claudiu; Demco, Dan E.; Istrate, Monica; Balaceanu, Andreea; Moldovan, Dumitrita; Fechete, Radu; Popescu, Crisan; Möller, Martin

    2009-10-01

    The effect of hydration on phase composition, aminoacids side-chain dynamics, and domain thickness of hard α-keratin was investigated by 1H solid-state NMR. Decomposition of wide-line 1H NMR spectra was used to determine the phase composition and to obtain information on molecular motion. Proton spin-diffusion NMR experiments using a double-quantum dipolar filter were used to estimate the rigid domain sizes for the hydrated Caucasian hair fibres. The relative domain sizes were obtained from the solution of spin-diffusion equation for cylindrical morphologies in the initial-rate approximation by a novel approach. A qualitative model describing the morphological and molecular dynamics changes induced by hydration was developed.

  8. Resonator Sensitivity Optimization in Magnetic Resonance and the Development of a Magic Angle Spinning Probe for the NMR Study of Rare Spin Nuclei on Catalytic Surfaces.

    Science.gov (United States)

    Doty, Francis David

    The sensitivity of an arbitrary resonator for the detection of a magnetic resonance signal is derived from basic energy considerations, and is shown to be dependent on V(,s)/t(,90)P(' 1/2). The radiation damping time constant is shown to be inversely dependent on the rf filling factor. Several resonators are analyzed in detail. The optimum solenoid is shown to have a length of about 1.5 times the diameter. The multilayer solenoid and the capacitively shortened slotted line resonator are shown to have advantages for samples with high dielectric losses. The capacitively shortened slotted line resonator is shown to substantially reduce acoustic ringing problems. Efficient methods are discussed for double and triple tuning these resonators. A slotted cylindrical resonator is described which gives higher sensitivity and faster response time than conventional cavities for very small samples at X-band ESR frequencies. Double tuned circuits using lumped elements are shown to be generally more efficient than those using transmission lines in generating rf fields. The optimum inductance ratio of the two coils in a ('13)C, ('1)H CP experiment is about 3. The high speed cylindrical sample spinner is analyzed in terms of compressible fluid dynamics, resonant modes, and structural analysis to arrive at optimum air bearing and spinner design recommendations. The optimum radial clearance is shown to depend on the 1/3 power of the rotor diameter. The required air bearing hole diameter has a square root dependence on the rotor diameter. Air pockets are shown to increase the resonant frequencies. Relevant data for a number of high strength insulators including hard ceramics are tabulated, and limiting speeds are calculated. CP MAS experiments on a 5% monolayer of n-butylamine absorbed on (gamma)-alumina reveal six lines. By comparison with the liquid phase spectrum it was determined that at least two types of chemically different surface species were present and that surface

  9. 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.

  10. Exploring catalyst passivation with NMR relaxation.

    Science.gov (United States)

    Robinson, Neil; Gladden, Lynn F; D'Agostino, Carmine

    2017-10-26

    NMR relaxation has recently emerged as a novel and non-invasive tool for probing the surface dynamics of adsorbate molecules within liquid-saturated mesoporous catalysts. The elucidation of such dynamics is of particular relevance to the study and development of solvated green catalytic processes, such as the production of chemicals and fuels from bio-resources. In this paper we develop and implement a protocol using high field 1 H NMR spin-lattice relaxation as a probe of the reorientational dynamics of liquids imbibed within mesoporous oxide materials. The observed relaxation of liquids within mesoporous materials is highly sensitive to the adsorbed surface layer, giving insight into tumbling behaviour of spin-bearing chemical environments at the pore surface. As a prototypical example of relevance to liquid-phase catalytic systems, we examine the mobility of liquid methanol within a range of common catalyst supports. In particular, through the calculation and comparison of a suitable interaction parameter, we assess and quantify changes to these surface dynamics upon replacing surface hydroxyl groups with hydrophobic alkyl chains. Our results indicate that the molecular tumbling of adsorbed methanol is enhanced upon surface passivation due to the suppression of surface-adsorbate hydrogen bonding interactions, and tends towards that of the unrestricted bulk liquid. A complex analysis in which we account for the influence of changing pore structure and surface chemistry upon passivation is discussed. The results presented highlight the use of NMR spin-lattice relaxation measurements as a non-invasive probe of molecular dynamics at surfaces of interest to liquid-phase heterogeneous catalysis.

  11. NMR Studies of Peroxidases.

    Science.gov (United States)

    Veitch, Nigel Charles

    Available from UMI in association with The British Library. Requires signed TDF. Peroxidases are a haem-containing group of enzymes with a wide diversity of function within biological systems. While a common characteristic is the ability to catalyse the conversion of hydrogen peroxide to water, it is the accompanying processes of hormone synthesis and degradation which have generated such a high level of interest. However, information at the molecular level is limited to a single well-resolved crystal structure, that of yeast cytochrome c peroxidase. This thesis presents a strategy for the investigation of peroxidase structure and function based on proton nuclear magnetic resonance spectroscopy, a technique which has the ability to address aspects of both protein structure and protein dynamics in solution. The application of one- and two-dimensional NMR techniques has been developed in the context of plant peroxidases, notably the isoenzyme HRP-C derived from the horseradish root. Characterisation of the proton NMR spectra of HRP -C in resting and ligated states provided new information enabling the structure of the binding site for aromatic donor molecules, such as indole-3-propionic, ferulic and benzhydroxamic acids, to be resolved. In order to overcome difficulties encountered with a protein of the complexity of peroxidase, additional information was obtained from chemical shift parameters and the use of peroxidase variants produced by site-directed mutagenesis. A comparative study using NMR spectroscopy was undertaken for wild-type recombinant HRP-C expressed in Escherichia coli, and two protein variants with substitutions made to residues located on the distal side of the haem pocket, Phe41 to Val and Arg38 to Lys. NMR analyses of a plant peroxidase from barley grains and the fungal peroxidase from Coprinus cinereus were also successful using methods conceived with HRP-C. Examination of three specifically constructed recombinant protein variants of C. cinereus

  12. NMR, water and plants

    International Nuclear Information System (INIS)

    As, H. van.

    1982-01-01

    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 π pulses in combination with a linear magnetic field gradient. (Auth.)

  13. Hydrate Shell Growth Measured Using NMR.

    Science.gov (United States)

    Haber, Agnes; Akhfash, Masoumeh; Loh, Charles K; Aman, Zachary M; Fridjonsson, Einar O; May, Eric F; Johns, Michael L

    2015-08-18

    Benchtop nuclear magnetic resonance (NMR) pulsed field gradient (PFG) and relaxation measurements were used to monitor the clathrate hydrate shell growth occurring in water droplets dispersed in a continuous cyclopentane phase. These techniques allowed the growth of hydrate inside the opaque exterior shell to be monitored and, hence, information about the evolution of the shell's morphology to be deduced. NMR relaxation measurements were primarily used to monitor the hydrate shell growth kinetics, while PFG NMR diffusion experiments were used to determine the nominal droplet size distribution (DSD) of the unconverted water inside the shell core. A comparison of mean droplet sizes obtained directly via PFG NMR and independently deduced from relaxation measurements showed that the assumption of the shell model-a perfect spherical core of unconverted water-for these hydrate droplet systems is correct, but only after approximately 24 h of shell growth. Initially, hydrate growth is faster and heat-transfer-limited, leading to porous shells with surface areas larger than that of spheres with equivalent volumes. Subsequently, the hydrate growth rate becomes mass-transfer-limited, and the shells become thicker, spherical, and less porous.

  14. NMR spectroscopic study and DFT calculations of GIAO NMR ...

    African Journals Online (AJOL)

    1H, proton coupled and decoupled 13C, DEPT, HETCOR NMR spectra, the magnitude of one bond 1JCH coupling constants and 13C NMR spin-lattice relaxation time (T1) of 1,9-diaminononane (danon, C9H22N2) have been reported for the first time. 1H, 13C NMR chemical shifts and 1JCH coupling constants of danon ...

  15. NMR imaging of the spine

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.S. (Case Western Reserve Univ. School of Medicine, Cleveland, OH); Kaufman, B.; El Yousef, S.J.; Benson, J.E.; Bonstelle, C.T.; Alfidi, R.J.; Haaga, J.R.; Yeung, H.; Huss, R.G.

    1983-12-01

    The usefulness of nuclear magnetic resonance (NMR) images in the evaluation of spinal disorders below the craniocervical junction was studied. Six normal subjects and 41 patients with various spinal abnormalities were examined. NMR proved capable of demonstrating important normal and pathologic anatomic structures; it was useful in the evaluation of syringohydromyelia and cystic spinal cord tumors, and the bright signal intensity of lipoma was quite impressive. In the evaluation of herniated disk, NMR images offered a new perspective by visualizing abnormal degradation of the signal intensity of the nucleus pulposus itself. NMR images were least valuable in the evaluation of spondylosis and spinal stenosis. Although NMR imaging of the spine is still in a very early developmental stage, the absence of both ionizing radiation and risks associated with contrast material makes it especially attractive as a new diagnostic method. This limited experience with currently available equipment suggests that, with technical refinement, the efficacy of NMR of the spine will increase.

  16. Solid-state NMR studies of supercapacitors.

    Science.gov (United States)

    Griffin, John M; Forse, Alexander C; Grey, Clare P

    2016-01-01

    Electrochemical double-layer capacitors, or 'supercapacitors' are attracting increasing attention as high-power energy storage devices for a wide range of technological applications. These devices store charge through electrostatic interactions between liquid electrolyte ions and the surfaces of porous carbon electrodes. However, many aspects of the fundamental mechanism of supercapacitance are still not well understood, and there is a lack of experimental techniques which are capable of studying working devices. Recently, solid-state NMR has emerged as a powerful tool for studying the local environments and behaviour of electrolyte ions in supercapacitor electrodes. In this Trends article, we review these recent developments and applications. We first discuss the basic principles underlying the mechanism of supercapacitance, as well as the key NMR observables that are relevant to the study of supercapacitor electrodes. We then review some practical aspects of the study of working devices using ex situ and in situ methodologies and explain the key advances that these techniques have allowed on the study of supercapacitor charging mechanisms. NMR experiments have revealed that the pores of the carbon electrodes contain a significant number of electrolyte ions in the absence of any charging potential. This has important implications for the molecular mechanisms of supercapacitance, as charge can be stored by different ion adsorption/desorption processes. Crucially, we show how in situ NMR experiments can be used to quantitatively study and characterise the charging mechanism, with the experiments providing the most detailed picture of charge storage to date, offering the opportunity to design enhanced devices. Finally, an outlook for future directions for solid-state NMR in supercapacitor research is offered. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Processing DOSY NMR Data by Chemometric Methods

    NARCIS (Netherlands)

    Huo, R.

    2006-01-01

    DOSY NMR can be used as a non-invasive separation method for complex mixtures. It is more and more attractive for industrial laboratories, for the main advantage DOSY NMR over routine separation methods such as LC-NMR is easy and economical implementation. With NMR instruments, DOSY NMR data can be

  18. nmr spectroscopic study and dft calculations of giao nmr shieldings

    African Journals Online (AJOL)

    Preferred Customer

    NMR is a sensitive and versatile probe of molecular-scale structure and dynamics in solids and liquids. It has been widely used in chemistry, materials and geochemistry [21-23] and it enables one to get faster and easier structural information. The standard 1D and 2D hetero and homonuclear NMR experiments are enough ...

  19. THz Dynamic Nuclear Polarization NMR.

    Science.gov (United States)

    Nanni, Emilio A; Barnes, Alexander B; Griffin, Robert G; Temkin, Richard J

    2011-08-29

    Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The enhancement in NMR sensitivity can amount to a factor of well above 100, enabling faster data acquisition and greatly improved NMR measurements. With the increasing magnetic fields (up to 23 T) used in NMR research, the required frequency for DNP falls into the THz band (140-600 GHz). Gyrotrons have been developed to meet the demanding specifications for DNP NMR, including power levels of tens of watts; frequency stability of a few megahertz; and power stability of 1% over runs that last for several days to weeks. Continuous gyrotron frequency tuning of over 1 GHz has also been demonstrated. The complete DNP NMR system must include a low loss transmission line; an optimized antenna; and a holder for efficient coupling of the THz radiation to the sample. This paper describes the DNP NMR process and illustrates the THz systems needed for this demanding spectroscopic application. THz DNP NMR is a rapidly developing, exciting area of THz science and technology.

  20. NMR imaging studies of coal

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Z.R.; Zhang, P.Z.; Ding, G.L.; Li, L.Y.; Ye, C.H. [University of Science and Technology, Beijing (China). Dept. of Chemistry

    1996-06-01

    The permeation transportation and swelling behavior of solvents into coal are investigated by NMR imaging using pyridine-d{sub 5} and acetone-d{sub 6}. Images of coal swollen with deuterated solvents illuminate proton distributions of mobile phases within the coal macromolecular networks. More information about the chemical and physical structure of coal can be obtained using NMR imaging techniques.

  1. NMR imaging of osteoarticular pathology

    Energy Technology Data Exchange (ETDEWEB)

    Frocrain, L.; Duvauferrier, R.; Gagey, N. and others

    1987-01-01

    NMR imaging is assuming an increasingly important role in the diagnosis of osteo-articular disorders. Semiological descriptions of the mean pathological disorders of the locomotor system are presented. Some investigation strategies are proposed to compare NMR imaging with other imaging techniques in various pathological states.

  2. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  3. Quantum Information Processing by NMR

    Indian Academy of Sciences (India)

    Keywords. NMR; quantum information processing; quantum computing; qubits; pseudopure states; quantum; pseudopure states; quantum gates; quantum simulations; decoherence. ... T S Mahesh1. Department of Physics and NMR Research Center, Indian Institute of Science Education and Research, Pune 411 008, India ...

  4. Resistive NMR of intracranial hematomas

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, R.A.; Bilaniuk, L.T.; Grossman, R.I.; Levine, R.S.; Lynch, R.; Goldberg, H.I.; Samuel, L.; Edelstein, W.; Bottomley, P.; Redington, R.W.

    1985-01-01

    Comparison between computed tomography and nuclear magnetic resonance imaging in 17 patients with intracranial hematomas indicate a distinct role for NMR in evaluating the stable patient with hematoma. NMR is useful for delineating the extent of the hematoma, the relationship of the hematoma to brain anatomy, and the presence of hematoma at a time when the hematoma is isodense on CT.

  5. 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...

  6. 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.

  7. 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

  8. Nonclassical dynamics of the methyl group in 1,1,1-triphenylethane. Evidence from powder 1H NMR spectra

    KAUST Repository

    Osior, Agnieszka

    2017-03-14

    According to the damped quantum rotation (DQR) theory, hindered rotation of methyl groups, evidenced in nuclear magnetic resonance (NMR) line shapes, is a nonclassical process. It comprises a number of quantum-rate processes measured by two different quantum-rate constants. The classical jump model employing only one rate constant is reproduced if these quantum constants happen to be equal. The values of their ratio, or the nonclassicallity coefficient, determined hitherto from NMR spectra of single crystals and solutions range from about 1.20 to 1.30 in the latter case to above 5.0 in the former, with the value of 1 corresponding to the jump model. Presently, first systematic investigations of the DQR effects in wide-line NMR spectra of a powder sample are reported. For 1,1,1-triphenylethane deuterated in the aromatic positions, the relevant line-shape effects were monitored in the range 99–121 K. The values of the nonclassicality coefficient dropping from 2.7 to 1.7 were evaluated in line shape fits to the experimental powder spectra from the range 99–108 K. At these temperatures, the fits with the conventional line-shape model are visibly inferior to the DQR fits. Using a theoretical model reported earlier, a semiquantitative interpretation of the DQR parameters evaluated from the spectra is given. It is shown that the DQR effects as such can be detected in wide-line NMR spectra of powdered samples, which are relatively facile to measure. However, a fully quantitative picture of these effects can only be obtained from the much more demanding experiments on single crystals.

  9. NMR Studies of Polymer Nanocomposites

    National Research Council Canada - National Science Library

    Greenbaum, Steve

    2001-01-01

    .... The primary tool is pulsed field gradient NMR. A static field gradient method was developed which makes possible variable pressure diffusion measurement, and the application to the important fuel cell membrane NAFION constitute the first results...

  10. β-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 β-NMR project at the ISOLDE facility. The β-NMR technique is well-established in solid-state physics and just recently it is being introduced for applications in biochemistry and life sciences. The β-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.

  11. Interpretations of NMR images

    International Nuclear Information System (INIS)

    Shi, J.Z.; McFarland, W.D.; Chen, S.S.; Sadhu, V.K.

    1986-01-01

    Two color display schemes are generally considered in medical images: pseudo-color and color composite. Psuedo-color technique maps the intensity means of a single monochrome image into a three dimensional color space, the gray level is thus replaced by the assigned color. Such a psuedo-color assignment is somewhat arbitrary but may be advantageous if the monochrome image is composed of simple intensity patterns. A good example of psuedo-color application is in nuclear medicine: The change of gray levels can be simply determined and the isocounts from two regions with different surroundings can be readily recognized. However, the use of psuedo-color in CT or MR imaging is controversial because it does not give additional information and may exaggerate insignificant gray scale differences. The color composite technique maps three parametric image data into a three dimensional color space, and thus three monochrome images are merged to form a single color image. The color composite technique increases the number of ways information can be displayed and provides both quantitative and qualitative data about the object or event represented. This paper describes the application of color composite in NMR images

  12. NMR imaging in theory and in practice

    International Nuclear Information System (INIS)

    Taylor, D.G.; Inamdar, R.; Bushell, M.-C.

    1988-01-01

    This review, completed in 1988, covers basic theory, NMR imaging (selective excitation, image acquisition and reconstruction, spatial localisation of NMR parameters, factors affecting accuracy of NMR parameters, image quality considerations), and NMR imaging in clinical practice. The authors conclude that current NMR technology enables one to image the human body with a clarity matching x-ray CT, in terms of contrast differentiation in soft tissues being superior. (U.K.)

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

    International Nuclear Information System (INIS)

    Matwiyoff, N.A.

    1983-01-01

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

    Energy Technology Data Exchange (ETDEWEB)

    Matwiyoff, N.A.

    1983-01-01

    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.

  15. From single-site tantalum complexes to nanoparticles of Ta x N y and TaO x N y supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy.

    Science.gov (United States)

    Mohandas, Janet C; Abou-Hamad, Edy; Callens, Emmanuel; Samantaray, Manoja K; Gajan, David; Gurinov, Andrei; Ma, Tao; Ould-Chikh, Samy; Hoffman, Adam S; Gates, Bruce C; Basset, Jean-Marie

    2017-08-01

    Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of Ta x N y and TaO x N y with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe 5 (Me = methyl) and dimeric Ta 2 (OMe) 10 with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of 1 H, 13 C, 29 Si, and 15 N at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O 2 insertion into Ta-CH 3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta 2 (OMe) 10 on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H 2 O 2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as Ta x N y /TaO x N y .

  16. Whole-core analysis by 13C NMR

    International Nuclear Information System (INIS)

    Vinegar, H.J.; Tutunjian, P.N.; Edelstein, W.A.; Roemer, P.B.

    1991-01-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance 13 C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. 13 C NMR can be used in cores where the 1 H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. 13 C/ 1 H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good 13 C signal/noise ratio (SNR) is obtained within minutes, while 1 H spectra are obtained in seconds. NMR measurements have been made of the 13 C and 1 H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the 13 C and 1 H signal per unit volume is constant within about 3.5%. For heavy crudes, the 13 C and 1 H density measured by NMR is reduced by the shortening of spin-spin relaxation time. 13 C and 1 H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60 degrees API), and alkanes (C 5 through C 16 ) with viscosities at 77 degrees F ranging from 0.5 cp to 2.5 x 10 7 cp. The 13 C and 1 H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The 13 C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled 13 C NMR is shown to be insensitive to kerogen; thus, 13 C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the 13 C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon

  17. NMR-based milk metabolomics

    DEFF Research Database (Denmark)

    Sundekilde, Ulrik; Larsen, Lotte Bach; Bertram, Hanne Christine S.

    2013-01-01

    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...

  18. Further development of deuterium NMR

    International Nuclear Information System (INIS)

    Al-azzawi, N.A.Y.

    1983-01-01

    In this work dichlorotris (triphenylphosphine) ruthenium (11) (RuCl 2 (PPh 3 ) 3 ) coupled with the deuterium source D 2 O was used as a catalyst for the study of the isotopic exchange reaction in alcohols and amines deuterium labelling of several primary and secondary alcohols have been made, and the position of labelling in the molecule was established by comparison of the 1 H NMR and 2 H NMR spectra while the relative distribution of deuterium was obtained from 2 H NMR spectrum. An oxidation-reduction mechanism was proposed for the hydrogen-deuterium exchange process, since in case of secondary alcohol the anticipated intermediate product (Ketone) was separated and identified. The relative distribution of deuterium was found to be time-dependent. Moreover the labelling in the B. Position was found to increase up on the addition of sodium hydroxide to the reaction mixture. 80 tabs.; 290 figs.; 124 refs

  19. Flow NMR of complex systems

    Energy Technology Data Exchange (ETDEWEB)

    Scheler, U.; Bagusat, F. [Leibniz-Inst. fuer Polymerforschung Dresden e.V., Dresden (Germany)

    2007-07-01

    A combination of NMR imaging and pulsed field gradient (PFG) NMR is applied to investigate flow. NMR longitudinal relaxation is used to generate contrast in a binary system of oil and water. The spatial distribution of each component and its flow pattern are measured separately. As a model a Couette cell with an additional area of high shear is used as model geometry. While a flat smooth interface is found at rest, the interface become bent under rotation, finally emulgation starts because of the velocity differences between the components. Flow from a submillimeter tube into a wide box and out of the box is investigated as well to understand shear-induced mixing and demixing. (orig.)

  20. Proton NMR studies of functionalized nanoparticles in aqueous environments

    Science.gov (United States)

    Tataurova, Yulia Nikolaevna

    Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results

  1. NMR spectroscopic study and DFT calculations of GIAO NMR ...

    African Journals Online (AJOL)

    1H, 13C NMR chemical shifts and 1JCH coupling constants of danon have been calculated by means of B3LYP density functional method with 6-311++G(d,p) basis set. Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for ...

  2. NMR data-driven structure determination using NMR-I-TASSER in the CASD-NMR experiment

    OpenAIRE

    Jang, Richard; Wang, Yan; Xue, Zhidong; Zhang, Yang

    2015-01-01

    NMR-I-TASSER, an adaption of the I-TASSER algorithm combining NMR data for protein structure determination, recently joined the second round of the CASD-NMR experiment. Unlike many molecular dynamics-based methods, NMR-I-TASSER takes a molecular replacement-like approach to the problem by first threading the target through the PDB to identify structural templates which are then used for iterative NOE assignments and fragment structure assembly refinements. The employment of multiple templates...

  3. 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...

  4. Developments in Solid-State NMR

    Indian Academy of Sciences (India)

    reso/020/11/1040-1052. Keywords. NMR; solid state; anisotropy; magic angle spinning dipolar coupling; quadrupolar coupling; chemical shift. Author Affiliations. K V Ramanathan1. NMR Research Center, Indian Institute of Science, Bengaluru ...

  5. Understanding NMR: self-learning manual

    International Nuclear Information System (INIS)

    Kastler, B.

    2000-01-01

    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.)

  6. Characterizing carbohydrate-protein interactions by NMR

    Science.gov (United States)

    Bewley, Carole A.; Shahzad-ul-Hussan, Syed

    2013-01-01

    Interactions between proteins and soluble carbohydrates and/or surface displayed glycans are central to countless recognition, attachment and signaling events in biology. The physical chemical features associated with these binding events vary considerably, depending on the biological system of interest. For example, carbohydrate-protein interactions can be stoichiometric or multivalent, the protein receptors can be monomeric or oligomeric, and the specificity of recognition can be highly stringent or rather promiscuous. Equilibrium dissociation constants for carbohydrate binding are known to vary from micromolar to millimolar, with weak interactions being far more prevalent; and individual carbohydrate binding sites can be truly symmetrical or merely homologous, and hence, the affinities of individual sites within a single protein can vary, as can the order of binding. Several factors, including the weak affinities with which glycans bind their protein receptors, the dynamic nature of the glycans themselves, and the non-equivalent interactions among oligomeric carbohydrate receptors, have made NMR an especially powerful tool for studying and defining carbohydrate-protein interactions. Here we describe those NMR approaches that have proven to be the most robust in characterizing these systems, and explain what type of information can (or cannot) be obtained from each. Our goal is to provide to the reader the information necessary for selecting the correct experiment or sets of experiments to characterize their carbohydrate-protein interaction of interest. PMID:23784792

  7. NMR study of strongly correlated electron systems

    Science.gov (United States)

    Kitaoka, Y.; Tou, H.; Zheng, G.-q.; Ishida, K.; Asayama, K.; Kobayashi, T. C.; Kohda, A.; Takeshita, N.; Amaya, K.; Onuki, Y.; Geibel, G.; Schank, C.; Steglich, F.

    1995-02-01

    Various types of ground states in strongly correlated electron systems have been systematically investigated by means of NMR/NQR at low temperatures under high magnetic field and pressure. We focus on two well-known heavy-electron families, CeCu 2X 2 (X = Si and Ge) (Ce(122)) and UM 2Al 3 (M = Ni and Pd) (U(123)). The Cu NQR experiments on CeCu 2X 2 under high pressure indicate that the physical property of CeCu 2Ge 2 at high pressure, i.e. above the transition at 7.6 GPa from antiferromagnetic (AF) to superconductivity, are clearly related to tha CeCu 2Si 2 at ambient pressure. In addition to the H-T phase diagram established below 7 T, NMR and specific heat experiments on polycrystal CeCu 2.05Si 2 have revealed the presence of a new phase above 7 T. In a high-quality polycrystal of UPd 2Al 3 with a record high- Tc of 2 K at ambient pressure and the narrowest Al NQR line width, the nuclear-spin lattice relaxation rate, 27(1/ T1) measured in zero field has been found to obey the T3 law down to 0.13 K, giving strong evidence that the energy gap vanishes along lines on the Fermi surface. Thus it seems that all heavy-electron superconductors exhibit lines of zero gap, regardless of their different magnetic properties.

  8. Fourier transform n.m.r. spectroscopy

    International Nuclear Information System (INIS)

    Shaw, D.

    1976-01-01

    This book is orientated to techniques rather than applications. The basic theory of n.m.r. is dealt with in a unified approach to the Fourier theory. The middle section of the book concentrates on the practical aspects of Fourier n.m.r., both instrumental and experimental. The final chapters briefly cover general application of n.m.r., but concentrate strongly on those areas where Fourier n.m.r. can give information which is not available by conventional techniques

  9. 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,

  10. Structures of Biomolecules by NMR Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    solution makes NMR more suitable for studying the dynamic behavior of macromolecules. The first high resolution protein structure by NMR spectroscopy was carried out in mid-1980s [3]. Before the beginning of this millennium, NMR spectroscopy was limited to solving 3D struc- tures of proteins with molecular masses less ...

  11. Development of Two-Dimensional NMR

    Indian Academy of Sciences (India)

    IAS Admin

    The development of Fourier transform NMR in the mid. 1960's, did parallel processing of the collection of NMR data, increased the signal/noise ratio by two orders of magnitude and made it possible to record the proton NMR spectra of small proteins which contain hundreds of resonances. The assignment of these ...

  12. Polymers under mechanical stress- an NMR investigation

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, Ute; Scheler, Ulrich [Leibniz Institute of Polymer Research Dresden (Germany); Xu, Bo; Leisen, Johannes; Beckham, Haskell W. [Georgia Institute of Technology, Atlanta, Georgia (United States)

    2010-07-01

    Low-field NMR using permanent magnets in Halbach arrangements permit NMR investigation without the limits present in high-field NMR. The lower field in conjunction with confined stray field permit the application of NMR, in particular relaxation NMR in a stretching apparatus and a rheometer. Crystalline and amorphous fraction of semi-crystalline polymers are distinguished by their transverse relaxation times. Upon mechanical load the relaxation times of the amorphous fraction changes as seen in in-situ measurements on polypropylene rods. During the formation of a neck the crystalline fraction becomes more prominent.

  13. NMR Measurements of Granular Flow and Compaction

    Science.gov (United States)

    Fukushima, Eiichi

    1998-03-01

    Nuclear magnetic resonance (NMR) can be used to measure statistical distributions of granular flow velocity and fluctuations of velocity, as well as spatial distributions of particulate concentration, flow velocity, its fluctuations, and other parameters that may be derived from these. All measurements have been of protons in liquid-containing particles such as mustard seeds or pharmaceutical pills. Our favorite geometry has been the slowly rotating partially filled rotating drum with granular flow taking place along the free surface of the particles. All the above-mentioned parameters have been studied as well as a spatial distribution of particulate diffusion coefficients, energy dissipation due to collisions, as well as segregation of non-uniform mixtures of granular material. Finally, we describe some motions of granular material under periodic vibrations.

  14. 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.

  15. NMR imaging of human atherosclerosis

    International Nuclear Information System (INIS)

    Toussaint, J.F.

    1995-01-01

    Diagnosis and prognosis of atherosclerosis can no longer be evaluated with morphological parameters only. A description of atherosclerotic plaque composition is necessary to study the mechanisms of plaque rupture, which depends on collagenous cap and lipid core thicknesses. NMR, as a biochemical imaging technique, allows visualization of these components using T1 contrast (mobile lipids), T2 contrast (cap vs. core), spin density (calcifications), diffusion imaging, 1H and 13C spectroscopy. Today, these imaging sequences allow to study in vitro the effects of interventional techniques such as angioplasty or atherectomy. Clinical investigations begin, which will attempt to develop in vivo microscopy and test the ability of NMR to predict plaque rupture. (author). 13 refs., 7 figs

  16. PVT Degradation Studies: NMR Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Herman M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-06-06

    Under certain environmental conditions, polyvinyl toluene (PVT) plastic scintillator has been observed to undergo internal fogging. Nuclear magnetic resonance spectroscopy has been used to elucidate the state of water inside the PVT. The deuterium NMR results show that water absorbed by PVT under warm, humid conditions enters several distinct environments, and when the PVT is transferred from incubation to ambient temperature and humidity the water is lost on a time scale of a few hours from these samples. Most of the deuterium NMR peaks can be assigned to bulk liquid water, but almost 35% of the detected signal intensity is contained in a resonance that resembles spectra of water contained in nanometer-scale pores in mesoporous carbon.

  17. Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

    DEFF Research Database (Denmark)

    Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike

    2017-01-01

    , as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6-cm diameter samples...... for laboratory measurements. We present a detailed comparison of the acquired laboratory- and logging-NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near......-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements....

  18. Picoliter NMR spectroscopy using nitrogen-vacancy centers in nanofabricated diamond

    Science.gov (United States)

    Kehayias, Pauli; Jarmola, Andrey; Mosavian, Nazanin; Fescenko, Ilja; Benito, Francisco; Laraoui, Abdelghani; Smits, Janis; Bougas, Lykourgos; Budker, Dmitry; Neumann, Alex; Brueck, Steven; Acosta, Victor

    2017-04-01

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for analytical chemistry, though one drawback is that its utility can be limited by poor sensitivity. This makes NMR characterization challenging for samples with few nuclear spins. Building on the recent advances of using nitrogen-vacancy (NV) color centers in diamond for NMR spectroscopy, we used an NV ensemble (a few-nm layer at the diamond surface) to improve sensitivity, which we further enhance by nanofabricating gratings for greater surface area. With nanofabricated diamond chips we detected the NMR signal from 1 molar 19F in glycerol in a 1 pL volume with nearly 100 × improvement in concentration sensitivity compared to previous reported works. We will present details on our recent findings and ongoing attempts to use this technique in practical applications.

  19. 3D Reconstruction of NMR Images by LabVIEW

    Directory of Open Access Journals (Sweden)

    Peter IZAK

    2007-01-01

    Full Text Available This paper introduces the experiment of 3D reconstruction NMR images via virtual instrumentation - LabVIEW. The main idea is based on marching cubes algorithm and image processing implemented by module of Vision assistant. The two dimensional images shot by the magnetic resonance device provide information about the surface properties of human body. There is implemented algorithm which can be used for 3D reconstruction of magnetic resonance images in biomedical application.

  20. Unraveling the meaning of chemical shifts in protein NMR.

    Science.gov (United States)

    Berjanskii, Mark V; Wishart, David S

    2017-11-01

    Chemical shifts are among the most informative parameters in protein NMR. They provide wealth of information about protein secondary and tertiary structure, protein flexibility, and protein-ligand binding. In this report, we review the progress in interpreting and utilizing protein chemical shifts that has occurred over the past 25years, with a particular focus on the large body of work arising from our group and other Canadian NMR laboratories. More specifically, this review focuses on describing, assessing, and providing some historical context for various chemical shift-based methods to: (1) determine protein secondary and super-secondary structure; (2) derive protein torsion angles; (3) assess protein flexibility; (4) predict residue accessible surface area; (5) refine 3D protein structures; (6) determine 3D protein structures and (7) characterize intrinsically disordered proteins. This review also briefly covers some of the methods that we previously developed to predict chemical shifts from 3D protein structures and/or protein sequence data. It is hoped that this review will help to increase awareness of the considerable utility of NMR chemical shifts in structural biology and facilitate more widespread adoption of chemical-shift based methods by the NMR spectroscopists, structural biologists, protein biophysicists, and biochemists worldwide. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Solid-state NMR of inorganic semiconductors.

    Science.gov (United States)

    Yesinowski, James P

    2012-01-01

    Studies of inorganic semiconductors by solid-state NMR vary widely in terms of the nature of the samples investigated, the techniques employed to observe the NMR signal, and the types of information obtained. Compared with the NMR of diamagnetic non-semiconducting substances, important differences often result from the presence of electron or hole carriers that are the hallmark of semiconductors, and whose theoretical interpretation can be involved. This review aims to provide a broad perspective on the topic for the non-expert by providing: (1) a basic introduction to semiconductor physical concepts relevant to NMR, including common crystal structures and the various methods of making samples; (2) discussions of the NMR spin Hamiltonian, details of some of the NMR techniques and strategies used to make measurements and theoretically predict NMR parameters, and examples of how each of the terms in the Hamiltonian has provided useful information in bulk semiconductors; (3) a discussion of the additional considerations needed to interpret the NMR of nanoscale semiconductors, with selected examples. The area of semiconductor NMR is being revitalized by this interest in nanoscale semiconductors, the great improvements in NMR detection sensitivity and resolution that have occurred, and the current interest in optical pumping and spintronics-related studies. Promising directions for future research will be noted throughout.

  2. Investigating sorption on iron-oxyhydroxide soil minerals by solid-state NMR spectroscopy: a 6Li MAS NMR study of adsorption and absorption on goethite

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Paik, Younkee; Julmis, Keinia

    2005-01-01

    High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, th...... on the goethite surface. Even larger Li hyperfine shifts (289 ppm) were observed for Li+-exchanged goethite, which contains lithium ions in the tunnels of the goethite structure, confirming the Li assignment of the 145 ppm Li resonance to the surface sites. Udgivelsesdato: 2005-Oct-6...

  3. An Inversion Recovery NMR Kinetics Experiment

    OpenAIRE

    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 article will enable instructors to use inversion recovery as a laboratory activity in applied NMR classes and provide research students with a conveni...

  4. Fourier Analysis and Structure Determination. Part II: Pulse NMR and NMR Imaging.

    Science.gov (United States)

    Chesick, John P.

    1989-01-01

    Uses simple pulse NMR experiments to discuss Fourier transforms. Studies the generation of spin echoes used in the imaging procedure. Shows that pulse NMR experiments give signals that are additions of sinusoids of differing amplitudes, frequencies, and phases. (MVL)

  5. Solution NMR structure determination of proteins revisited

    International Nuclear Information System (INIS)

    Billeter, Martin; Wagner, Gerhard; Wuethrich, Kurt

    2008-01-01

    This 'Perspective' bears on the present state of protein structure determination by NMR in solution. The focus is on a comparison of the infrastructure available for NMR structure determination when compared to protein crystal structure determination by X-ray diffraction. The main conclusion emerges that the unique potential of NMR to generate high resolution data also on dynamics, interactions and conformational equilibria has contributed to a lack of standard procedures for structure determination which would be readily amenable to improved efficiency by automation. To spark renewed discussion on the topic of NMR structure determination of proteins, procedural steps with high potential for improvement are identified

  6. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

    NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions

  7. NMR in structure-based drug design.

    Science.gov (United States)

    Carneiro, Marta G; Ab, Eiso; Theisgen, Stephan; Siegal, Gregg

    2017-11-08

    NMR spectroscopy is a powerful technique that can provide valuable structural information for drug discovery endeavors. Here, we discuss the strengths (and limitations) of NMR applications to structure-based drug discovery, highlighting the different levels of resolution and throughput obtainable. Additionally, the emerging field of paramagnetic NMR in drug discovery and recent developments in approaches to speed up and automate protein-observed NMR data collection and analysis are discussed. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  8. NMR characterization of pituitary tumors

    International Nuclear Information System (INIS)

    Osbakken, M.; Gonzales, J.; Page, R.

    1984-01-01

    Twelve patients (5 male, 7 female, mean age 37.9 +- 20) with pituitary tumors were extensively evaluated with NMR imaging using a 1.5K gauss resistive magnet. Saturation recovery (SR), inversion recovery (IR) and spin echo (SE) pulse sequences were used for qualitative characterization of the lesions. T/sub 1/ calculations were also performed for brain and pituitary. Tumor histology and endocrine status were correlated with NMR data. All tumors were large with suprasellar extension (6 with prolactin secretion, 6 without). Pituitary T/sub 1/'s ranged from .2 to .64, the mean T/sub 1/ being longer than that of brain (Brain = .4 +- .04; Pit = .48 +- .14). 3 patients with histological evidence of homogeneous adenomas had long T/sub 1/'s (0.58 +- .05). 3 patients with evidence of recent or old hemorhage into the pituitary had much shorter T/sub 1/'s (0.29 +- .12). There was no relationship between prolactin secretion and T/sub 1/. Qualitative T/sub 1/ and T/sub 2/ information can be obtained by using a combination of SR, IR, and SE images. Using this method in the patients, homogeneous adenomas had similar T/sub 1/'s and longer T/sub 2/'s compared to the brain, while patients with bleeds had shorter T/sub 1/'s and T/sub 2/'s. Image T/sub 1/ characteristics correlated well with the calculated T/sub 1/ values. The range of T/sub 1/ (and potentially T/sub 2/) values which occur in apparently similar lesions are most likely due to anatomical and pathophysiological variations in these lesions. It may be ultimately possible to separate different types of pathological processes based on NMR image T/sub 1/ and T/sub 2/ characteristics after careful comparative studies of NMR and histological data are completed. The combination of calculated T/sub 1/ and T/sub 2/ with image T/sub 1/ and T/sub 2/ information may also be useful in further characterization of lesions

  9. Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR

    NARCIS (Netherlands)

    Van Der Schot, Gijs; Bonvin, Alexandre M J J

    We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on

  10. 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…

  11. NMR studies of oriented molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sinton, S.W.

    1981-11-01

    Deuterium and proton magnetic resonance are used in experiments on a number of compounds which either form liquid crystal mesophases themselves or are dissolved in a liquid crystal solvent. Proton multiple quantum NMR is used to simplify complicated spectra. The theory of nonselective multiple quantum NMR is briefly reviewed. Benzene dissolved in a liquid crystal are used to demonstrate several outcomes of the theory. Experimental studies include proton and deuterium single quantum (..delta..M = +-1) and proton multiple quantum spectra of several molecules which contain the biphenyl moiety. 4-Cyano-4'-n-pentyl-d/sub 11/-biphenyl (5CB-d/sub 11/) is studied as a pure compound in the nematic phase. The obtained chain order parameters and dipolar couplings agree closely with previous results. Models for the effective symmetry of the biphenyl group in 5CB-d/sub 11/ are tested against the experimental spectra. The dihedral angle, defined by the planes containing the rings of the biphenyl group, is found to be 30 +- 2/sup 0/ for 5DB-d/sub 11/. Experiments are also described for 4,4'-d/sub 2/-biphenyl, 4,4' - dibromo-biphenyl, and unsubstituted biphenyl.

  12. Permeability Estimation in Chalk Using NMR and a Modified Kozeny Equation

    DEFF Research Database (Denmark)

    Meireles, Leonardo Teixeira Pinto; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    2017-01-01

    calibration. To translate the T2 relaxation distribution into pore size, an analogy is made between the NMR T2 data and the MICP output. Specific surface data acquired by the Brunauer Emmett Teller method (BET) was used to aid the interpretation of the surface relaxivity. The model was tested in a chalk...

  13. New techniques in NMR spectroscopy

    International Nuclear Information System (INIS)

    Hughes, C.E.

    1998-10-01

    In 1989, Soerensen introduced a method, the unitary bound, for calculating the maximum efficiencies of coherence transfer processes in NMR. This thesis applies this method to quadrupolar nuclei, an area not investigated by Soerensen. In doing so, several questions are raised, and answered, as to the implications of the unitary bound for coherence transfer processes in all areas of NMR. These include discussions of when such processes can be reversed without loss of signal and when sequential coherence transfer steps can be carried out with both steps having the maximum efficiency. One area of NMR of quadrupolar nuclei which has attracted some interest over the past few years has been the selective excitation of 23 Na nuclei in ordered environments. This was hinted at by Jaccard et al. in 1986 and demonstrated in biological systems by Eliav et al. in 1992, who achieved the selective excitation using a double-quantum filtration (DQF) experiment. The following year, Kemp-Harper and Wimperis demonstrated that the Jeener-Broekaert experiment could be used to achieve the same selectivity through excitation of quadrupolar order. The unitary bound shows that neither of these experiments achieve the maximum coherence transfer efficiency. This thesis sets out to improve upon the efficiency of these two experiments. Two multiple-pulse experiments are investigated. One seeks to improve upon the efficiency of the Jeener-Broekaert experiment for spin I = 3/2 nuclei by 33% to achieve the unitary bound efficiency. The other seeks to improve the efficiency of the selective DQF experiment by 41% to achieve the bound for spin I= 3/2 nuclei. 23 Na NMR spectra of cartilage and a lyotropic liquid crystal are presented which show that, although the new version of the Jeener-Broekaert experiment achieves no greater efficiency in practical application than the original, the new DQF experiment produces up to half of the expected improvement in efficiency. Alternative techniques to the

  14. Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, Raz [Univ. of California, Berkeley, CA (United States)

    1993-07-01

    Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. 27Al and 23Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework 27Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na+ cations are directly involved in adsorption processes and reactions in zeolite cavities.

  15. Multinuclear MAS NMR studies on coked zeolites H-ZSM-5

    International Nuclear Information System (INIS)

    Ernst, H.; Freude, D.; Hunger, M.; Pfeifer, H.

    1991-01-01

    During the cracking process carbonaceous materials are deposited on the outer or inner surface of the catalyst. These deposits are in many cases the main cause of catalyst deactivation. Magic angle spinning (MAS) NMR investigations and catalytic n-hexane cracking were carried out on H-ZSM-5 zeolites after a mild hydrothermal de-alumination. By 13 C CP MAS NMR it could be shown that the enhanced catalytic activity does not enhance the coke formation and that the chemical nature of these deposits is essentially aromatic. From 1 H MAS NMR studies performed on shallow-bed activated sealed samples and 27 Al and 29 Si MAS NMR on rehydrated samples it follows that for high coke concentrations the catalyst deactivation is caused mainly by blocking of Broensted acid sites. (author). 27 refs.; 3 figs.; 2 tabs

  16. Solid state NMR studies of materials for energy technology

    Science.gov (United States)

    Nambukara Kodiweera Arachchilage, Chandana K.

    Presented in this dissertation are NMR investigations of the dynamical and structural properties of materials for energy conversion and storage devices. 1H and 2H NMR was used to study water and methanol transportation in sulfonated poly(arylene ether ketone) based membranes for direct methanol fuel cells (DMFC). These results are presented in chapter 3. The amount of liquid in the membrane and ion exchange capacity (IEC) are two main factors that govern the dynamics in these membranes. Water and methanol diffusion coefficients also are comparable. Chapters 4 and 5 are concerned with 31P and 1H NMR in phosphoric acid doped PBI membranes (para-PBI and 2OH-PBI) as well as PBI membranes containing ionic liquids (H3PO4/PMIH2PO4/PBI). These membranes are designed for higher-temperature fuel cell operation. In general, stronger short and long range interactions were observed in the 2OH-PBI matrix, yielding reduced proton transport compared to that of para-PBI. In the case of H3PO4/PMIH2PO 4/PBI, both conductivity and diffusion are higher for the sample with molar ratio 2/4/1. Finally, chapter 6 is devoted to the 31P NMR MAS study of phosphorus-containing structural groups on the surfaces of micro/mesoporous activated carbons. Two spectral features were observed and the narrow feature identifies surface phosphates while the broad component identifies heterogeneous subsurface phosphorus environments including phosphate and more complex structure multiple P-C, P-N and P=N bonds.

  17. NMR Analysis of Some Pentacycloundecanedione Derivatives

    African Journals Online (AJOL)

    NJD

    was used to assist with the elucidation of the asymmetric ketal structure. KEYWORDS. NMR elucidation, pentacycloundecane, 2D NMR. 1. Introduction. The chemistry ... intermediate for the diol 413,14 which is used in the synthesis of various crown ethers13,15–17 and macrocycles.11,18. 2. Experimental. The four products ...

  18. A Guided Inquiry Approach to NMR Spectroscopy

    Science.gov (United States)

    Parmentier, Laura E.; Lisensky, George C.; Spencer, Brock

    1998-04-01

    We present a novel way to introduce NMR spectroscopy into the general chemistry curriculum as part of a week-long aspirin project in our one-semester introductory course. Aspirin is synthesized by reacting salicylic acid and acetic anhydride. Purity is determined by titration and IR and NMR spectroscopy. Students compare IR and NMR spectra of their aspirin product to a series of reference spectra obtained by the class. Students are able to interpret the IR spectra of their aspirin using IR data from previous experiments. NMR is introduced by having students collect 1H NMR spectra of a series of reference compounds chosen to include some of the structural features of aspirin and compare spectra and structures of the reference compounds to develop a correlation chart for chemical shifts. This process is done in small groups using shared class data and is guided by a series of questions designed to relate the different kinds of hydrogen atoms to number and position of peaks in the NMR spectrum. Students then identify the peaks in the NMR spectrum of their aspirin product and relate percent purity by titration with spectral results and percent yield. This is an enjoyable project that combines the synthesis of a familiar material with a guided inquiry-based introduction to NMR spectroscopy.

  19. Synthesis and NMR Elucidation of Novel Pentacycloundecane ...

    African Journals Online (AJOL)

    Herein we report the synthesis and NMR elucidation of five novel pentacycloundecane (PCU)-derived short peptides as potential HIV protease inhibitors. 1H and 13C spectral analysis show major overlapping of methine resonance of the PCU 'cage' thereby making it extremely difficult to assign the NMR signals. Attachment ...

  20. Early history of NMR at Los Alamos

    International Nuclear Information System (INIS)

    Jackson, J.A.

    1985-11-01

    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

  1. Using Cloud Storage for NMR Data Distribution

    Science.gov (United States)

    Soulsby, David

    2012-01-01

    An approach using Google Groups as method for distributing student-acquired NMR data has been implemented. We describe how to configure NMR spectrometer software so that data is uploaded to a laboratory section specific Google Group, thereby removing bottlenecks associated with printing and processing at the spectrometer workstation. Outside of…

  2. 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...

  3. Dynamic NMR Study of Model CMP Slurry Containing Silica Particles as Abrasives

    Science.gov (United States)

    Odeh, F.; Al-Bawab, A.; Li, Y.

    2018-02-01

    Chemical mechanical planarization (CMP) should provide a good surface planarity with minimal surface defectivity. Since CMP slurries are multi-component systems, it is very important to understand the various processes and interactions taking place in such slurries. Several techniques have been employed for such task, however, most of them lack the molecular recognition to investigate molecular interactions without adding probes which in turn increase complexity and might alter the microenvironment of the slurry. Nuclear magnetic resonance (NMR) is a powerful technique that can be employed in such study. The longitudinal relaxation times (T1) of the different components of CMP slurries were measured using Spin Echo-NMR (SE-NMR) at a constant temperature. The fact that NMR is non-invasive and gives information on the molecular level gives more advantage to the technique. The model CMP slurry was prepared in D2O to enable monitoring of T1 for the various components' protons. SE-NMR provide a very powerful tool to study the various interactions and adsorption processes that take place in a model CMP silica based slurry which contains BTA and/or glycine and/or Cu+2 ions. It was found that BTA is very competitive towards complexation with Cu+2 ions and BTA-Cu complex adsorbs on silica surface.

  4. A small-diameter NMR logging tool for groundwater investigations

    Science.gov (United States)

    Walsh, David; Turner, Peter; Grunewald, Elliot; Zhang, Hong; Butler, James J.; Reboulet, Ed; Knobbe, Steve; Christy, Tom; Lane, John W.; Johnson, Carole D.; Munday, Tim; Fitzpatrick, Andrew

    2013-01-01

    A small-diameter nuclear magnetic resonance (NMR) logging tool has been developed and field tested at various sites in the United States and Australia. A novel design approach has produced relatively inexpensive, small-diameter probes that can be run in open or PVC-cased boreholes as small as 2 inches in diameter. The complete system, including surface electronics and various downhole probes, has been successfully tested in small-diameter monitoring wells in a range of hydrogeological settings. A variant of the probe that can be deployed by a direct-push machine has also been developed and tested in the field. The new NMR logging tool provides reliable, direct, and high-resolution information that is of importance for groundwater studies. Specifically, the technology provides direct measurement of total water content (total porosity in the saturated zone or moisture content in the unsaturated zone), and estimates of relative pore-size distribution (bound vs. mobile water content) and hydraulic conductivity. The NMR measurements show good agreement with ancillary data from lithologic logs, geophysical logs, and hydrogeologic measurements, and provide valuable information for groundwater investigations.

  5. Characterization of influenza hemagglutinin interactions with receptor by NMR.

    Directory of Open Access Journals (Sweden)

    Christopher McCullough

    Full Text Available In influenza, the envelope protein hemagglutinin (HA plays a critical role in viral entry by first binding to sialic acid receptors on the cell surface and subsequently mediating fusion of the viral and target membranes. In this work, the receptor binding properties of influenza A HA from different subtypes (H1 A/California/04/09, H5 A/Vietnam/1205/04, H5 A/bar-headed goose/Qinghai/1A/05, and H9 A/Hong Kong/1073/99 have been characterized by NMR spectroscopy. Using saturation transfer difference (STD NMR, we find that all HAs bind to the receptor analogs 2,3-sialyllactose and 2,6-sialyllactose, with subtle differences in the binding mode. Using competition STD NMR, we determine the receptor preferences for the HA subtypes. We find that H5-Qinghai and H9-Hong Kong HA bind to both receptor analogs with similar affinity. On the other hand, H1 exhibits a clear preference for 2,6-sialyllactose while H5-Vietnam exhibits a clear preference for 2,3-sialyllactose. Together, these results are interpreted within the context of differences in both the amino acid sequence and structures of HA from the different subtypes in determining receptor preference.

  6. An introduction to biological NMR spectroscopy

    International Nuclear Information System (INIS)

    Marion, Dominique

    2013-01-01

    NMR spectroscopy is a powerful tool for biologists interested in the structure, dynamics, and interactions of biological macromolecules. This review aims at presenting in an accessible manner the requirements and limitations of this technique. As an introduction, the history of NMR will highlight how the method evolved from physics to chemistry and finally to biology over several decades. We then introduce the NMR spectral parameters used in structural biology, namely the chemical shift, the J-coupling, nuclear Overhauser effects, and residual dipolar couplings. Resonance assignment, the required step for any further NMR study, bears a resemblance to jigsaw puzzle strategy. The NMR spectral parameters are then converted into angle and distances and used as input using restrained molecular dynamics to compute a bundle of structures. When interpreting a NMR-derived structure, the biologist has to judge its quality on the basis of the statistics provided. When the 3D structure is a priori known by other means, the molecular interaction with a partner can be mapped by NMR: information on the binding interface as well as on kinetic and thermodynamic constants can be gathered. NMR is suitable to monitor, over a wide range of frequencies, protein fluctuations that play a crucial role in their biological function. In the last section of this review, intrinsically disordered proteins, which have escaped the attention of classical structural biology, are discussed in the perspective of NMR, one of the rare available techniques able to describe structural ensembles. This Tutorial is part of the International Proteomics Tutorial Programme (IPTP 16 MCP). (authors)

  7. NMR reaction monitoring in flow synthesis

    Directory of Open Access Journals (Sweden)

    M. Victoria Gomez

    2017-02-01

    Full Text Available Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.

  8. The characterisation of polymers using pulsed NMR

    International Nuclear Information System (INIS)

    Charlesby, A.

    1983-01-01

    Broad line pulsed NMR is applied to obtain information on radiation-induced polymer changes and other aspects of polymer science based on the interpretation of spin-spin relaxation curves. Calculations are made to determine the molecular weight, the crosslink density of simple, low molecular weight, flexible polymers. For higher molecular weight polymers, a conclusion can be drawn on the concentrations of entangled and crosslinked units by means of pulsed NMR. Some typical applications of the technique are illustrated by the examples of polyethylenes, rubbers, filled polymeric systems and aqueous polyethylene oxide solutions. The morphology of polymers can be followed by pulsed NMR. (V.N.)

  9. 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)

  10. 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.

  11. Solid-state NMR of polymers

    International Nuclear Information System (INIS)

    Mirau, P.

    2001-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has emerged as one of the most important methods for the solid-state characterisation of polymers. The popularity of NMR is due to the fact that many molecular level features can be measured from the NMR spectra, including the polymer chain conformation, the morphology and the dynamics. The spectral features and relaxation times are affected by local interactions, so they provide information about the structure of polymers on a length scale (2-200 A) that is difficult to measure by other methods. In favourable cases, the NMR experiments provide a molecular-level explanation for the transitions observed by differential scanning calorimetry (DSC) and other methods, and the NMR properties can often be related to the bulk properties. Solid-state NMR has long been of interest in polymer science, and the first solid-state NMR studies of polymers were reported approximately a year after the discovery of nuclear resonance in bulk matter. It was reported in this initial study that the proton line width for natural rubber at room temperature is more like that of a mobile liquid than of a solid, but that the resonance broadens near the glass transition temperature (T g ). This was recognised as being related to a change in chain dynamics above and below the T g . NMR methods developed rapidly after these initial observations, first for polymers in solution and, more recently, for polymers in the solid-state. Solid-state NMR studies of polymers were developed more slowly than their solution-state counterparts because solid-state NMR requires more specialised equipment. Solid-state NMR is now such an important tool that most modern spectrometers are capable of performing these studies. The interest in the NMR of solid polymers is due in part to the fact that most polymers are used in the solid state, and in many cases the NMR properties can be directly related to the macroscopic properties. Polymers have restricted mobility in

  12. NMR data-driven structure determination using NMR-I-TASSER in the CASD-NMR experiment

    International Nuclear Information System (INIS)

    Jang, Richard; Wang, Yan; Xue, Zhidong; Zhang, Yang

    2015-01-01

    NMR-I-TASSER, an adaption of the I-TASSER algorithm combining NMR data for protein structure determination, recently joined the second round of the CASD-NMR experiment. Unlike many molecular dynamics-based methods, NMR-I-TASSER takes a molecular replacement-like approach to the problem by first threading the target through the PDB to identify structural templates which are then used for iterative NOE assignments and fragment structure assembly refinements. The employment of multiple templates allows NMR-I-TASSER to sample different topologies while convergence to a single structure is not required. Retroactive and blind tests of the CASD-NMR targets from Rounds 1 and 2 demonstrate that even without using NOE peak lists I-TASSER can generate correct structure topology with 15 of 20 targets having a TM-score above 0.5. With the addition of NOE-based distance restraints, NMR-I-TASSER significantly improved the I-TASSER models with all models having the TM-score above 0.5. The average RMSD was reduced from 5.29 to 2.14 Å in Round 1 and 3.18 to 1.71 Å in Round 2. There is no obvious difference in the modeling results with using raw and refined peak lists, indicating robustness of the pipeline to the NOE assignment errors. Overall, despite the low-resolution modeling the current NMR-I-TASSER pipeline provides a coarse-grained structure folding approach complementary to traditional molecular dynamics simulations, which can produce fast near-native frameworks for atomic-level structural refinement

  13. NMR data-driven structure determination using NMR-I-TASSER in the CASD-NMR experiment.

    Science.gov (United States)

    Jang, Richard; Wang, Yan; Xue, Zhidong; Zhang, Yang

    2015-08-01

    NMR-I-TASSER, an adaption of the I-TASSER algorithm combining NMR data for protein structure determination, recently joined the second round of the CASD-NMR experiment. Unlike many molecular dynamics-based methods, NMR-I-TASSER takes a molecular replacement-like approach to the problem by first threading the target through the PDB to identify structural templates which are then used for iterative NOE assignments and fragment structure assembly refinements. The employment of multiple templates allows NMR-I-TASSER to sample different topologies while convergence to a single structure is not required. Retroactive and blind tests of the CASD-NMR targets from Rounds 1 and 2 demonstrate that even without using NOE peak lists I-TASSER can generate correct structure topology with 15 of 20 targets having a TM-score above 0.5. With the addition of NOE-based distance restraints, NMR-I-TASSER significantly improved the I-TASSER models with all models having the TM-score above 0.5. The average RMSD was reduced from 5.29 to 2.14 Å in Round 1 and 3.18 to 1.71 Å in Round 2. There is no obvious difference in the modeling results with using raw and refined peak lists, indicating robustness of the pipeline to the NOE assignment errors. Overall, despite the low-resolution modeling the current NMR-I-TASSER pipeline provides a coarse-grained structure folding approach complementary to traditional molecular dynamics simulations, which can produce fast near-native frameworks for atomic-level structural refinement.

  14. AEM and NMR: Tools for the Future of Groundwater Management

    Science.gov (United States)

    Abraham, J. D.; Cannia, J. C.; Lawrie, K.

    2012-12-01

    Within the world, understanding groundwater resources and their management are growing in importance to society as groundwater resources are stressed by drought and continued development. To minimize conflicts, tools and techniques need to be applied to support knowledge-based decisions and management. Airborne electromagnetic (AEM) surveys provide high-quality subsurface data not available from any other source for building the complex hydrogeologic frameworks needed by water-resource managers for effective groundwater management. Traditionally, point data, such as borehole logs, borehole geophysics, surface geophysics, and aquifer tests were interpolated over long distances to create hydrogeologic frameworks. These methods have enjoyed a long history of being the best available technology to inform our understanding of groundwater and how it moves. The AEM techniques proivde pathway for geoscientists to follow to develop more accurate descriptions of the hydrogeological framework. However, the critical and challenging measurements in characterizing aquifers include effective porosity and hydraulic conductivity. These parameters are not reliable derived from AEM. Typically, values for effective porosity and hydraulic conductivity are derived by lithological comparisons with published data; direct measurements of hydraulic conductivity acquired by a few constant head aquifer tests or slug tests; and expensive and time consuming laboratory measurements of cores which can be biased by sampling and the difficulty of making measurements on unconsolidated materials. Aquifer tests are considered to be the best method to gather information on hydraulic conductivity but are rare because of cost and difficult logistics. Also they are unique in design and interpretation from site to site. Nuclear Magnetic Resonance (NMR) can provide a direct measurement of the presence of water in the pore space of aquifer materials. Detection and direct measurement is possible due to the

  15. Nuclear Magnetic Resonance (NMR) Spectroscopic Characterization of Nanomaterials and Biopolymers

    Science.gov (United States)

    Guo, Chengchen

    Nanomaterials have attracted considerable attention in recent research due to their wide applications in various fields such as material science, physical science, electrical engineering, and biomedical engineering. Researchers have developed many methods for synthesizing different types of nanostructures and have further applied them in various applications. However, in many cases, a molecular level understanding of nanoparticles and their associated surface chemistry is lacking investigation. Understanding the surface chemistry of nanomaterials is of great significance for obtaining a better understanding of the properties and functions of the nanomaterials. Nuclear magnetic resonance (NMR) spectroscopy can provide a familiar means of looking at the molecular structure of molecules bound to surfaces of nanomaterials as well as a method to determine the size of nanoparticles in solution. Here, a combination of NMR spectroscopic techniques including one- and two-dimensional NMR spectroscopies was used to investigate the surface chemistry and physical properties of some common nanomaterials, including for example, thiol-protected gold nanostructures and biomolecule-capped silica nanoparticles. Silk is a natural protein fiber that features unique properties such as excellent mechanical properties, biocompatibility, and non-linear optical properties. These appealing physical properties originate from the silk structure, and therefore, the structural analysis of silk is of great importance for revealing the mystery of these impressive properties and developing novel silk-based biomaterials as well. Here, solid-state NMR spectroscopy was used to elucidate the secondary structure of silk proteins in N. clavipes spider dragline silk and B. mori silkworm silk. It is found that the Gly-Gly-X (X=Leu, Tyr, Gln) motif in spider dragline silk is not in a beta-sheet or alpha-helix structure and is very likely to be present in a disordered structure with evidence for 31-helix

  16. Structural investigations of substituted indolizine derivatives by NMR studies

    International Nuclear Information System (INIS)

    Furdui, Bianca; Dinica, Rodica; Demeunynck, Martine; Druta, Ioan

    2008-01-01

    Owing to the increasing importance of indolizine heterocycles in the field of biology and pharmacology we have synthesized and investigated the obtained heterocycles by NMR techniques. In order to investigate the substituent effects on the spectroscopic properties, a series of indolizine derivatives were studied by 1 H-NMR, 13 C-NMR and 2D NMR (GCOSY, GHMBC and GHMQC spectra). (authors)

  17. Simultaneous acquisition of three NMR spectra in a single ...

    Indian Academy of Sciences (India)

    reduce the acquisition time of high-dimensional NMR spectra for metabolomics.8 The different fast NMR methods and their combinations developed during the past decade for proteins and nucleic acids such as single-scan NMR spectroscopy (ultrafast NMR),9–13. HADMARD encoding,14 reduced dimensional (RD). 1091 ...

  18. 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.

  19. Cultural Heritage Studies with Mobile NMR.

    Science.gov (United States)

    Rehorn, Christian; Blümich, Bernhard

    2018-03-30

    Nuclear Magnetic Resonance (NMR) provides in-situ information about selected isotope densities in samples and objects, while also providing contrast through rotational and translational molecular dynamics. These parameters are probed not only in magnetic resonance spectroscopy and imaging but also in nondestructive materials testing by mobile stray-field NMR whose unique perks are valuable in cultural heritage studies. We present recent progress in the analysis of cultural heritage with mobile 1H NMR stray-field sensors, for which the detection zone is outside of the NMR magnet. Prominent applications include the analysis of stratigraphies in paintings and frescoes, and the assessment of material states changing under the impact of aging, conservation and restoration. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Development of Two-Dimensional NMR

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 11. Development of Two-Dimensional NMR: Strucure Determination of Biomolecules in Solution. Anil Kumar. General Article Volume 20 Issue 11 November 2015 pp 995-1002 ...

  1. NMR study of Albemoschus esculentus characterization

    International Nuclear Information System (INIS)

    Bathista, A.L.B.S; Silva, E.O.; Nogueira, Jose de S.; Tavares, M.I.B.

    2001-01-01

    The investigation of the main compounds presented in the Albemoschus esculentus has been carried out employing nuclear magnetic resonance spectroscopy (NMR), using solution and solid state NMR when it one was necessary. The evaluation of NMR data allowed us to characterize the main type of components presented in this kind of sample. It was necessary to use a total information from solid state NMR and also the solution response. From these information we could get that four main components were presented in this sample. One in the shell, that is cellulose, another one between the shell and seeds that is a polysaccharide and in the seed two components were found one is a starch and the second one is an oil, a triacylglycerol. These components are responsible by its physical chemistry properties. (author)

  2. NMR analysis of compositional heterogeneity in polysaccharides

    Science.gov (United States)

    Many copolysaccharides are compositionally heterogeneous, and the composition determined by the usual analytical or spectroscopic methods provides only an average value. For some polysaccharides, the NMR data contain copolymer sequence information, such as diad, triad, and tetrad sequence intensiti...

  3. Bayesian Peak Picking for NMR Spectra

    Directory of Open Access Journals (Sweden)

    Yichen Cheng

    2014-02-01

    Full Text Available 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.

  4. 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.

  5. NMR spectroscopy in the characterization of asphalt

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, P.W.; Desando, M.A.; Raub, M.F.; Hoberg, J.O.; Moats, R.; Stewart, F.F. (Montana State Univ., Bozeman (United States))

    1990-07-01

    NMR spectrometry represents a probe which can provide many details regarding the structure and functionality of asphalts. This is particularly true if it is combined with chromatography and/or chemical modifications. In this project {sup 1}H, {sup 2}H, {sup 13}C, {sup 19}F, {sup 29}Si, {sup 31}P nuclei and a variety of NMR techniques (1D, 2D, DEPT) have been used to describe a few chemical characteristics of the asphalts and chromatographic fractions therefrom.

  6. New insights into glycopeptide antibiotic binding to cell wall precursors using SPR and NMR spectroscopy.

    Science.gov (United States)

    Treviño, Juan; Bayón, Carlos; Ardá, Ana; Marinelli, Flavia; Gandolfi, Raffaella; Molinari, Francesco; Jimenez-Barbero, Jesús; Hernáiz, María J

    2014-06-10

    Glycopeptide antibiotics, such as vancomycin and teicoplanin, are used to treat life-threatening infections caused by multidrug-resistant Gram-positive pathogens. They inhibit bacterial cell wall biosynthesis by binding to the D-Ala-D-Ala C-terminus of peptidoglycan precursors. Vancomycin-resistant bacteria replace the dipeptide with the D-Ala-D-Lac depsipeptide, thus reducing the binding affinity of the antibiotics with their molecular targets. Herein, studies of the interaction of teicoplanin, teicoplanin-like A40926, and of their semisynthetic derivatives (mideplanin, MDL63,246, dalbavancin) with peptide analogues of cell-wall precursors by NMR spectroscopy and surface plasmon resonance (SPR) are reported. NMR spectroscopy revealed the existence of two different complexes in solution, when the different glycopeptides interact with Ac2KdAlaDAlaOH. Despite the NMR experimental conditions, which are different from those employed for the SPR measurements, the NMR spectroscopy results parallel those deduced in the chip with respect to the drastic binding difference existing between the D-Ala and the D-Lac terminating analogues, confirming that all these antibiotics share the same primary molecular mechanism of action and resistance. Kinetic analysis of the interaction between the glycopeptide antibiotics and immobilized AcKdAlaDAlaOH by SPR suggest a dimerization process that was not observed by NMR spectroscopy in DMSO solution. Moreover, in SPR, all glycopeptides with a hydrophobic acyl chain present stronger binding with a hydrophobic surface than vancomycin, indicating that additional interactions through the employed surface are involved. In conclusion, SPR provides a tool to differentiate between vancomycin and other glycopeptides, and the calculated binding affinities at the surface seem to be more relevant to in vitro antimicrobial activity than the estimations from NMR spectroscopy analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Monitoring an Induced Permafrost Warming Experiment Using ERT, Temperature, and NMR in Fairbanks, Alaska

    Science.gov (United States)

    Ulrich, C.; Ajo Franklin, J. B.; Ekblaw, I.; Lindsey, N.; Wagner, A. M.; Saari, S.; Daley, T. M.; Freifeld, B. M.

    2016-12-01

    As global temperatures continue to rise, permafrost landscapes will experience more rapid changes than other global climate zones. Permafrost thaw is a result of increased temperatures in arctic settings resulting in surface deformation and subsurface hydrology changes. From an engineering perspective, surface deformation poses a threat to the stability of existing infrastructure such as roads, utility piping, and building structures. Preemptively detecting or monitoring subsurface thaw dynamics presents a difficult challenge due to the long time scales as deformation occurs. Increased subsurface moisture content results from permafrost thaw of which electrical resistivity tomography (ERT), soil temperature, and nuclear magnetic resonance (NMR) are directly sensitive. In this experiment we evaluate spatial and temporal changes in subsurface permafrost conditions (moisture content and temperature) at a experimental heating plot in Fairbanks, AK. This study focuses on monitoring thaw signatures using multiple collocated electrical resistivity (ERT), borehole temperature, and borehole nuclear magnetic resonance (NMR) measurements. Timelapse ERT (sensitive to changes in moisture content) was inverted using collocated temperature and NMR to constrain ERT inversions. Subsurface thermal state was monitored with timelapse thermistors, sensitive to soil ice content. NMR was collected in multiple boreholes and is sensitive to changes in moisture content and pore scale distribution. As permafrost thaws more hydrogen, in the form of water, is available resulting in a changing NMR response. NMR requires the availability of liquid water in order to induce spin of the hydrogen molecule, hence, if frozen water molecules will be undetectable. In this study, the permafrost is poised close to 0oC and is mainly silt with small pore dimensions; this combination makes NMR particularly useful due to the possibility of sub-zero thaw conditions within the soil column. Overall this

  8. NMRbox: A Resource for Biomolecular NMR Computation.

    Science.gov (United States)

    Maciejewski, Mark W; Schuyler, Adam D; Gryk, Michael R; Moraru, Ion I; Romero, Pedro R; Ulrich, Eldon L; Eghbalnia, Hamid R; Livny, Miron; Delaglio, Frank; Hoch, Jeffrey C

    2017-04-25

    Advances in computation have been enabling many recent advances in biomolecular applications of NMR. Due to the wide diversity of applications of NMR, the number and variety of software packages for processing and analyzing NMR data is quite large, with labs relying on dozens, if not hundreds of software packages. Discovery, acquisition, installation, and maintenance of all these packages is a burdensome task. Because the majority of software packages originate in academic labs, persistence of the software is compromised when developers graduate, funding ceases, or investigators turn to other projects. To simplify access to and use of biomolecular NMR software, foster persistence, and enhance reproducibility of computational workflows, we have developed NMRbox, a shared resource for NMR software and computation. NMRbox employs virtualization to provide a comprehensive software environment preconfigured with hundreds of software packages, available as a downloadable virtual machine or as a Platform-as-a-Service supported by a dedicated compute cloud. Ongoing development includes a metadata harvester to regularize, annotate, and preserve workflows and facilitate and enhance data depositions to BioMagResBank, and tools for Bayesian inference to enhance the robustness and extensibility of computational analyses. In addition to facilitating use and preservation of the rich and dynamic software environment for biomolecular NMR, NMRbox fosters the development and deployment of a new class of metasoftware packages. NMRbox is freely available to not-for-profit users. Copyright © 2017 Biophysical Society. All rights reserved.

  9. A Solid-State NMR Study of Selenium Substitution into Nanocrystalline Hydroxyapatite

    Science.gov (United States)

    Kolmas, Joanna; Kuras, Marzena; Oledzka, Ewa; Sobczak, Marcin

    2015-01-01

    The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface. PMID:25997001

  10. Monitoring the Electrochemical Processes in the Lithium–Air Battery by Solid State NMR Spectroscopy

    Science.gov (United States)

    2013-01-01

    A multi-nuclear solid-state NMR approach is employed to investigate the lithium–air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13C ssNMR provides evidence for carbonate formation on the surface of the carbon cathode, the carbonate being removed at high charging voltages in the first cycle, but accumulating in later cycles. Small amounts of lithium hydroxide and formate are also detected in discharged cathodes and while the hydroxide formation is reversible, the formate persists and accumulates in the cathode upon further cycling. The results indicate that the rechargeability of the battery is limited by both the electrolyte and the carbon cathode stability. The utility of ssNMR spectroscopy in directly detecting product formation and decomposition within the battery is demonstrated, a necessary step in the assessment of new electrolytes, catalysts, and cathode materials for the development of a viable lithium–oxygen battery. PMID:24489976

  11. Monitoring the Electrochemical Processes in the Lithium-Air Battery by Solid State NMR Spectroscopy.

    Science.gov (United States)

    Leskes, Michal; Moore, Amy J; Goward, Gillian R; Grey, Clare P

    2013-12-27

    A multi-nuclear solid-state NMR approach is employed to investigate the lithium-air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17 O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13 C ssNMR provides evidence for carbonate formation on the surface of the carbon cathode, the carbonate being removed at high charging voltages in the first cycle, but accumulating in later cycles. Small amounts of lithium hydroxide and formate are also detected in discharged cathodes and while the hydroxide formation is reversible, the formate persists and accumulates in the cathode upon further cycling. The results indicate that the rechargeability of the battery is limited by both the electrolyte and the carbon cathode stability. The utility of ssNMR spectroscopy in directly detecting product formation and decomposition within the battery is demonstrated, a necessary step in the assessment of new electrolytes, catalysts, and cathode materials for the development of a viable lithium-oxygen battery.

  12. 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 μM taurine solutions, which is the level of sensitivity necessary for biological samples.

  13. Basics of spectroscopic instruments. Hardware of NMR spectrometer

    International Nuclear Information System (INIS)

    Sato, Hajime

    2009-01-01

    NMR is a powerful tool for structure analysis of small molecules, natural products, biological macromolecules, synthesized polymers, samples from material science and so on. Magnetic Resonance Imaging (MRI) is applicable to plants and animals Because most of NMR experiments can be done by an automation mode, one can forget hardware of NMR spectrometers. It would be good to understand features and performance of NMR spectrometers. Here I present hardware of a modern NMR spectrometer which is fully equipped with digital technology. (author)

  14. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T

    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...

  15. Estimating microstructural length scales in k-carrageenan hydrogels by PFG NMR nanoprobe diffusometry

    NARCIS (Netherlands)

    Kort, de D.W.; As, van H.; Duynhoven, van J.P.M.

    2016-01-01

    We use PFG NMR to measure hindered self-diffusion of spherical, monodisperse diffusional nanoprobes in a polysaccharide network.
    These nanoprobes have different diameters in the 1–10 nm range, but identical inert (PEG) surfaces. We use Johnson’s model of
    particle self-diffusion in fibrous

  16. 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…

  17. NMR Spectra through the Eyes of a Student: Eye Tracking Applied to NMR Items

    Science.gov (United States)

    Topczewski, Joseph J.; Topczewski, Anna M.; Tang, Hui; Kendhammer, Lisa K.; Pienta, Norbert J.

    2017-01-01

    Nuclear magnetic resonance spectroscopy (NMR) plays a key role in introductory organic chemistry, spanning theory, concepts, and experimentation. Therefore, it is imperative that the instruction methods for NMR are both efficient and effective. By utilizing eye tracking equipment, the researchers were able to monitor how second-semester organic…

  18. Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR.

    Science.gov (United States)

    van der Schot, Gijs; Bonvin, Alexandre M J J

    2015-08-01

    We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on unassigned NOE lists (Huang et al. in J Am Chem Soc 127:1665-1674, 2005b, doi: 10.1021/ja047109h). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 with recalculated targets using the new R3FP fragment picker for fragment selection and implementing a new annotation of prediction reliability (van der Schot et al. in J Biomol NMR 57:27-35, 2013, doi: 10.1007/s10858-013-9762-6), both implemented in the CS-Rosetta3 WeNMR server. In this second round of CASD-NMR, the WeNMR CS-Rosetta server has demonstrated a much better performance than in the first round since only converged targets were submitted. Further, recalculation of all CASD-NMR targets using the new version of the server demonstrates that our new annotation of prediction quality is giving reliable results. Predictions annotated as weak are often found to provide useful models, but only for a fraction of the sequence, and should therefore only be used with caution.

  19. New methods for the correction of 31P NMR spectra in in vivo NMR spectroscopy

    International Nuclear Information System (INIS)

    Starcuk, Z.; Bartusek, K.; Starcuk, Z. jr.

    1994-01-01

    The new methods for the correction of 31 P NMR spectra in vivo NMR spectroscopy have been performed. A method for the baseline correction of the spectra which represents a combination of time-domain and frequency-domain has been discussed.The method is very fast and efficient for minimization of base line artifacts of biological tissues impact

  20. NMR techniques in the study of cardiovascular structure and functions

    International Nuclear Information System (INIS)

    Osbakken, M.; Haselgrove, J.

    1987-01-01

    The chapter titles of this book are: Introduction to NMR Techniques;Theory of NMR Probe Design;Overview of Magnetic Resonance Imaging to Study the Cardiovascular System;Vascular Anatomy and Physiology Studied with NMR Techniques;Assessment of Myocardial Ischemia and Infarction by Nuclear Magnetic Resonance Imaging;The Use of MRI in Congenital Heart Disease;Cardiomyopathies and Myocarditis Studied with NMR Techniques;Determination of Myocardial Mechanical Function with Magnetic Resonance Imaging Techniques;Determination of Flow Using NMR Techniques;The Use of Contrast Agents in Cardiac MRI;Can Cardiovascular Disease Be Effectively Evaluated with NMR Spectroscopy? NMR Studies of ATP Synthesis Reactions in the Isolated Heart;Studies of Intermediary Metabolism in the Heart by 13C NMR Spectroscopy;23Na and 39K NMR Spectroscopic Studies of the Intact Beating Heart;and Evaluation of Skeletal Muscle Metabolism in Patients with Congestive Heart Failure Using Phosphorus Nuclear Magnetic Resonance

  1. NMR studies of cation transport across membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

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

    International Nuclear Information System (INIS)

    Quibilan, E.I.

    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)

  3. An investigation into the effects of pore connectivity on T2 NMR relaxation

    Science.gov (United States)

    Ghomeshi, Shahin; Kryuchkov, Sergey; Kantzas, Apostolos

    2018-04-01

    Nuclear Magnetic Resonance (NMR) is a powerful technique used to characterize fluids and flow in porous media. The NMR relaxation curves are closely related to pore geometry, and the inversion of the NMR relaxometry data is known to give useful information with regards to pore size distribution (PSD) through the relative amplitudes of the fluids stored in the small and large pores. While this information is crucial, the main challenge for the successful use of the NMR measurements is the proper interpretation of the measured signals. Natural porous media patterns consist of complex pore structures with many interconnected or "coupled" regions, as well as isolated pores. This connectivity along the throats changes the relaxation distribution and in order to properly interpret this data, a thorough understanding of the effects of pore connectivity on the NMR relaxation distribution is warranted. In this paper we address two main points. The first pertains to the fact that there is a discrepancy between the relaxation distribution obtained from experiments, and the ones obtained from solving the mathematical models of diffusion process in the digitized images of the pore space. There are several reasons that may attribute to this such as the lack of a proper incorporation of surface roughness into the model. However, here we are more interested in the effects of pore connectivity and to understand why the typical NMR relaxation distribution obtained from experiments are wider, while the numerical simulations predict that a wider NMR relaxation distribution may indicate poor connectivity. Secondly, by not taking into account the pore coupling effects, from our experience in interpreting the data, we tend to underestimate the pore volume of small pores and overestimate the amplitudes in the large pores. The role of pore coupling becomes even more prominent in rocks with small pore sizes such as for example in shales, clay in sandstones, and in the microstructures of

  4. The use of dielectric and NMR measurements to determine the pore-scale location of organic contaminants. 1997 annual progress report

    International Nuclear Information System (INIS)

    Bryar, T.; Caputi, M.; Knight, R.

    1997-01-01

    'The objective of the three-year research project is to investigate the effect of adsorbed organics on the dielectric and nuclear magnetic resonance (NMR) response of porous geological materials. This will allow us to assess the use of dielectric and NMR measurements at a site to determine whether organic contaminants are present in the central volume of the pore space (in a water-wet system) or are adsorbed to the solid surface. In addition, the authors propose to use laboratory dielectric and NMR measurements to study the kinetics of the adsorption and desorption of organics by conducting experiments where the authors control temperature and vary fluid chemistry. This project can be divided into three parts: sample preparation, NMR studies, dielectric studies. Over the past nine months the authors have made significant progress in sample preparation and NMR studies. As the plan is to conduct the NMR and dielectric measurements on the same set of samples, the authors delayed the start of the dielectric measurements until the first stage of NMR measurements were complete. Below the authors summarize the progress in sample preparation and NMR measurements, first briefly introducing the method used for the NMR measurements.'

  5. Remote tuning of NMR probe circuits.

    Science.gov (United States)

    Kodibagkar, V D; Conradi, M S

    2000-05-01

    There are many circumstances in which the probe tuning adjustments cannot be located near the rf NMR coil. These may occur in high-temperature NMR, low-temperature NMR, and in the use of magnets with small diameter access bores. We address here circuitry for connecting a fixed-tuned probe circuit by a transmission line to a remotely located tuning network. In particular, the bandwidth over which the probe may be remotely tuned while keeping the losses in the transmission line acceptably low is considered. The results show that for all resonant circuit geometries (series, parallel, series-parallel), overcoupling of the line to the tuned circuit is key to obtaining a large tuning bandwidth. At equivalent extents of overcoupling, all resonant circuit geometries have nearly equal remote tuning bandwidths. Particularly for the case of low-loss transmission line, the tuning bandwidth can be many times the tuned circuit's bandwidth, f(o)/Q. Copyright 2000 Academic Press.

  6. Flow NMR of polymers in external fields

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, Ute; Bagusat, Frank; Scheler, Ulrich [Leibniz Institute of Polymer Research Dresden (Germany)

    2008-07-01

    Pulsed-field gradient NMR is applied to study the motion of polymers in an external electric field and under mechanical shear. The application of an electric field drives motion of charged species. In conjunction with the diffusion coefficient from the electrophoretic mobility the effective charge per molecule is derived. The electric field applicable in the aqueous system is too weak to deform the polymer or even abstract counterions. In a shear flow established in a Couette cell partial orientation of polymer chains is measured via residual dipolar couplings. The entire flow field in a non-symmetric flow cell is monitored by a combination of PFG NMR and NMR imaging exhibiting regions of high shear and locally low shear, where polymers relax.

  7. Muscular pathology: echographic and NMR imaging aspects

    International Nuclear Information System (INIS)

    Pascal-Suisse, P.; Beaurain, P.; Mougniot, C.

    1995-01-01

    A comparison of echographic techniques and NMR imaging has been done for the diagnosis of muscular trauma and tumor pathologies. In traumatic pathology, the echographic analysis allows to determine the complete assessment of recent muscular injuries. NMR imaging can be used in granuloma or fibrous callosity appreciation and for the analysis of deep injury (muscles and muscles-tendon junctions) and of muscular aponeurosis. Echography must be used together with color coding Doppler technique in the diagnosis of tumor pathology and for the study of slow fluxes. The recently available energy Doppler technique seems to be powerful in the study of vascularization of small expansive formations, but their extension to adjacent bone or tissue can only be appreciated using NMR imaging. (J.S.)

  8. Deuterium NMR, induced and intrinsic cholesteric lyomesophases

    International Nuclear Information System (INIS)

    Alcantara, M.R.

    1982-01-01

    Induced and intrinsic cholesteric lyotropic mesophases were studied. Induced cholesteric lyomesophases based on potassium laurate (KL) system, with small amounts of cholesterol added, were studied by deuterium NMR and by polarizing microscopy. Order profiles obtained from deuterium NMR of KL perdenderated chains in both induced cholesteric and normal mesophases were compared. The intrinsic cholesteric lyotropic mesophases were based on the amphiphile potassium N-lauroyl serinate (KLNS) in the resolved levo form. The study of the type I intrinsic cholesteric mesophase was made by optical microscopy under polarized light and the type II intrinsic cholesteric lyomesophase was characterized by deuterium NMR. The new texture was explained by the use of the theory of disclinations developed for thermotropic liquid crystals, specially for cholesteric type. (M.J.C.) [pt

  9. NMR Evidence for the Topologically Nontrivial Nature in a Family of Half-Heusler Compounds

    KAUST Repository

    Zhang, Xiaoming

    2016-03-16

    Spin-orbit coupling (SOC) is expected to partly determine the topologically nontrivial electronic structure of heavy half-Heusler ternary compounds. However, to date, attempts to experimentally observe either the strength of SOC or how it modifies the bulk band structure have been unsuccessful. By using bulk-sensitive nuclear magnetic resonance (NMR) spectroscopy combined with first-principles calculations, we reveal that 209Bi NMR isotropic shifts scale with relativity in terms of the strength of SOC and average atomic numbers, indicating strong relativistic effects on NMR parameters. According to first-principles calculations, we further claim that nuclear magnetic shieldings from relativistic p1/2 states and paramagnetic contributions from low-lying unoccupied p3/2 states are both sensitive to the details of band structures tuned by relativity, which explains why the hidden relativistic effects on band structure can be revealed by 209Bi NMR isotropic shifts in topologically nontrivial half-Heusler compounds. Used in complement to surface-sensitive methods, such as angle resolved photon electron spectroscopy and scanning tunneling spectroscopy, NMR can provide valuable information on bulk electronic states.

  10. Prediction of peak overlap in NMR spectra

    International Nuclear Information System (INIS)

    Hefke, Frederik; Schmucki, Roland; Güntert, Peter

    2013-01-01

    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.

  11. Applications of NMR in biological metabolic research

    International Nuclear Information System (INIS)

    Nie Jiarui; Li Xiuqin; He Chunjian

    1989-01-01

    The nuclear magnetic resonance has become a powerful means of studying biological metabolism in non-invasive and non-destructive way. Being used to study the metabolic processes of living system in normal physiological conditions as well as in molecular level, the method is better than other conventional approaches. Using important parameters such as NMR-chemical shifts, longitudinal relaxation time and transverse relaxation time, it is possible to probe the metabolic processes as well as conformation, concentration, transportation and distribution of reacting and resulting substances. The NMR spectroscopy of 1 H, 31 P and 13 C nuclei has already been widely used in metabolic researches

  12. Programmable pulse series generator for NMR relaxometer

    International Nuclear Information System (INIS)

    Stolbunov, R.N.; Chichikov, S.A.; Lundin, A.G.

    2005-01-01

    Paper describes a pulse series generator for NMR relaxometer. The operation mode is set on the basis of the PC program by the PCI bus in the internal memory. The design is based on two Altera Company MAX7000S and Cyclone family microcircuits using the Qartus II 4.0 software. The basic parameters are as follows: pulse minimum length - 50 ns, time resolution - 10 ns, pulse maximum number - 1024, number of controlled output channels - 8. The designed device as a part of the NMR hardware-software system enables to record, to process and to store the experiment results in the form of electronic document [ru

  13. NMR studies of single crystal chromium diboride

    Energy Technology Data Exchange (ETDEWEB)

    Michioka, C. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)]. E-mail: michioka@kuchem.kyoto-u.ac.jp; Itoh, Y. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Yoshimura, K. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Watabe, Y. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558 (Japan); Kousaka, Y. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558 (Japan); Ichikawa, H. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558 (Japan); Akimitsu, J. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558 (Japan)

    2007-03-15

    We report {sup 11}B NMR studies of a single crystal CrB{sub 2}. From the temperature dependence of the Fourier-transformed NMR spectra in the paramagnetic state, the hyperfine coupling constants are estimated to be A{sub Cr-B} = -0.64,-0.74 and -0.71kOe/{mu}{sub B} for H parallel c, H parallel a and H parallel [210], respectively. In the magnetically ordered state, the spectra in H parallel a and H parallel [210] consist of superposition of a broad hump and five peaks, which correspond to the incommensurate and commensurate spin structures.

  14. Amphoteric surface active agents

    OpenAIRE

    Eissa, A.M. F.

    1995-01-01

    2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C12, C14, C16 and C18carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR) and nuclear magnetic resonance (NMR). Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height a...

  15. Use of earth field spin echo NMR to search for liquid minerals

    Science.gov (United States)

    Stoeffl, Wolfgang

    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.

  16. Final Report: DoE SBIR Phase 2 Low-Cost Small Diameter NMR Technologies for In-Situ Subsurface Characterization and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, David Oliver [Vista Clara Inc., Mukilteo, WA (United States)

    2010-09-03

    In this Phase 2 SBIR program, Vista Clara successfully developed and field-tested small diameter NNR logging tools for subsurface characterization and monitoring. This effort involved the design and development surface electronics, a winch with 470ft cable, and three interchangeable downhole probes: a 3.5â diameter borehole NMR probe, a 1.67â diameter borehole NMR probe, and a 2.5â diameter NMR probe that can be deployed using a Geoprobe direct push machine. The 3.5â probe was tested extensively over a 6 week period including 4â to 8â boreholes in Washington, Idaho, Nebraska, Colorado, Kansas, Connecticut and Massachusetts. The field test campaign was highly successful. The 1.67â probe was assembled, tested and calibrated in the laboratory. The 2.5â Geoprobe probe is in final assembly and testing at the time of this report. The completed Phase 2 R&D program has resulted in the first NMR logging tool that can be deployed in boreholes of 4â diameter, the first NMR logging tool that can be deployed in boreholes on 2â diameter, and the first NMR logging tool that can be deployed by a direct push machine. These small diameter tools make NMR logging technically and economically feasible, for the first time. Previously available NMR logging tools were developed for oilfield applications and are prohibitively large and expensive for the majority of near surface groundwater characterization problems.

  17. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

    OpenAIRE

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin; He, Lan

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same intern...

  18. 1H NMR spectra dataset and solid-state NMR data of cowpea (Vigna unguiculata).

    Science.gov (United States)

    Alves Filho, Elenilson G; Silva, Lorena M A; Teofilo, Elizita M; Larsen, Flemming H; de Brito, Edy S

    2017-04-01

    In this article the NMR data from chemical shifts, coupling constants, and structures of all the characterized compounds were provided, beyond a complementary PCA evaluation for the corresponding manuscript (E.G. Alves Filho, L.M.A. Silva, E.M. Teofilo, F.H. Larsen, E.S. de Brito, 2017) [3]. In addition, a complementary assessment from solid-state NMR data was provided. For further chemometric analysis, numerical matrices from the raw 1 H NMR data were made available in Microsoft Excel workbook format (.xls).

  19. Recommendations of the wwPDB NMR Validation Task Force

    Science.gov (United States)

    Montelione, Gaetano T.; Nilges, Michael; Bax, Ad; Güntert, Peter; Herrmann, Torsten; Richardson, Jane S.; Schwieters, Charles; Vranken, Wim F.; Vuister, Geerten W.; Wishart, David S.; Berman, Helen M.; Kleywegt, Gerard J.; Markley, John L.

    2013-01-01

    As methods for analysis of biomolecular structure and dynamics using nuclear magnetic resonance spectroscopy (NMR) continue to advance, the resulting 3D structures, chemical shifts, and other NMR data are broadly impacting biology, chemistry, and medicine. Structure model assessment is a critical area of NMR methods development, and is an essential component of the process of making these structures accessible and useful to the wider scientific community. For these reasons, the Worldwide Protein Data Bank (wwPDB) has convened an NMR Validation Task Force (NMR-VTF) to work with the wwPDB partners in developing metrics and policies for biomolecular NMR data harvesting, structure representation, and structure quality assessment. This paper summarizes the recommendations of the NMR-VTF, and lays the groundwork for future work in developing standards and metrics for biomolecular NMR structure quality assessment. PMID:24010715

  20. Current NMR Techniques for Structure-Based Drug Discovery.

    Science.gov (United States)

    Sugiki, Toshihiko; Furuita, Kyoko; Fujiwara, Toshimichi; Kojima, Chojiro

    2018-01-12

    A variety of nuclear magnetic resonance (NMR) applications have been developed for structure-based drug discovery (SBDD). NMR provides many advantages over other methods, such as the ability to directly observe chemical compounds and target biomolecules, and to be used for ligand-based and protein-based approaches. NMR can also provide important information about the interactions in a protein-ligand complex, such as structure, dynamics, and affinity, even when the interaction is too weak to be detected by ELISA or fluorescence resonance energy transfer (FRET)-based high-throughput screening (HTS) or to be crystalized. In this study, we reviewed current NMR techniques. We focused on recent progress in NMR measurement and sample preparation techniques that have expanded the potential of NMR-based SBDD, such as fluorine NMR ( 19 F-NMR) screening, structure modeling of weak complexes, and site-specific isotope labeling of challenging targets.

  1. nmrML: A Community Supported Open Data Standard for the Description, Storage, and Exchange of NMR Data.

    Science.gov (United States)

    Schober, Daniel; Jacob, Daniel; Wilson, Michael; Cruz, Joseph A; Marcu, Ana; Grant, Jason R; Moing, Annick; Deborde, Catherine; de Figueiredo, Luis F; Haug, Kenneth; Rocca-Serra, Philippe; Easton, John; Ebbels, Timothy M D; Hao, Jie; Ludwig, Christian; Günther, Ulrich L; Rosato, Antonio; Klein, Matthias S; Lewis, Ian A; Luchinat, Claudio; Jones, Andrew R; Grauslys, Arturas; Larralde, Martin; Yokochi, Masashi; Kobayashi, Naohiro; Porzel, Andrea; Griffin, Julian L; Viant, Mark R; Wishart, David S; Steinbeck, Christoph; Salek, Reza M; Neumann, Steffen

    2018-01-02

    NMR is a widely used analytical technique with a growing number of repositories available. As a result, demands for a vendor-agnostic, open data format for long-term archiving of NMR data have emerged with the aim to ease and encourage sharing, comparison, and reuse of NMR data. Here we present nmrML, an open XML-based exchange and storage format for NMR spectral data. The nmrML format is intended to be fully compatible with existing NMR data for chemical, biochemical, and metabolomics experiments. nmrML can capture raw NMR data, spectral data acquisition parameters, and where available spectral metadata, such as chemical structures associated with spectral assignments. The nmrML format is compatible with pure-compound NMR data for reference spectral libraries as well as NMR data from complex biomixtures, i.e., metabolomics experiments. To facilitate format conversions, we provide nmrML converters for Bruker, JEOL and Agilent/Varian vendor formats. In addition, easy-to-use Web-based spectral viewing, processing, and spectral assignment tools that read and write nmrML have been developed. Software libraries and Web services for data validation are available for tool developers and end-users. The nmrML format has already been adopted for capturing and disseminating NMR data for small molecules by several open source data processing tools and metabolomics reference spectral libraries, e.g., serving as storage format for the MetaboLights data repository. The nmrML open access data standard has been endorsed by the Metabolomics Standards Initiative (MSI), and we here encourage user participation and feedback to increase usability and make it a successful standard.

  2. Untangle soil-water-mucilage interactions: 1H NMR Relaxometry is lifting the veil

    Science.gov (United States)

    Brax, Mathilde; Buchmann, Christian; Schaumann, Gabriele Ellen

    2017-04-01

    Mucilage is mainly produced at the root tips and has a high water holding capacity derived from highly hydrophilic gel-forming substances. The objective of the MUCILAGE project is to understand the mechanistic role of mucilage for the regulation of water supply for plants. Our subproject investigates the chemical and physical properties of mucilage as pure gel and mixed with soil. 1H-NMR Relaxometry and PFG NMR represent non-intrusive powerful methods for soil scientific research by allowing quantification of the water distribution as well as monitoring of the water mobility in soil pores and gel phases.Relaxation of gel water differs from the one of pure water due to additional interactions with the gel matrix. Mucilage in soil leads to a hierarchical pore structure, consisting of the polymeric biohydrogel network surrounded by the surface of soil particles. The two types of relaxation rates 1/T1 and 1/T2 measured with 1H-NMR relaxometry refer to different relaxation mechanisms of water, while PFG-NMR measures the water self-diffusion coefficient. The objective of our study is to distinguish in situ water in gel from pore water in a simplified soil system, and to determine how the "gel effect" affects both relaxation rates and the water self-diffusion coefficient in porous systems. We demonstrate how the mucilage concentration and the soil solution alter the properties of water in the respective gel phases and pore systems in model soils. To distinguish gel-inherent processes from classical processes, we investigated the variations of the water mobility in pure chia mucilage under different conditions by using 1H-NMR relaxometry and PFG NMR. Using model soils, the signals coming from pore water and gel water were differentiated. We combined the equations describing 1H-NMR relaxation in porous systems and our experimental results, to explain how the presence of gel in soil affects 1H-NMR relaxation. Out of this knowledge we propose a method, which determines in

  3. NMR experiments on a three-dimensional vibrofluidized granular medium

    Science.gov (United States)

    Huan, Chao; Yang, Xiaoyu; Candela, D.; Mair, R. W.; Walsworth, R. L.

    2004-04-01

    A three-dimensional granular system fluidized by vertical container vibrations was studied using pulsed field gradient NMR coupled with one-dimensional magnetic resonance imaging. The system consisted of mustard seeds vibrated vertically at 50 Hz, and the number of layers Nl⩽4 was sufficiently low to achieve a nearly time-independent granular fluid. Using NMR, the vertical profiles of density and granular temperature were directly measured, along with the distributions of vertical and horizontal grain velocities. The velocity distributions showed modest deviations from Maxwell-Boltzmann statistics, except for the vertical velocity distribution near the sample bottom, which was highly skewed and non-Gaussian. Data taken for three values of Nl and two dimensionless accelerations Γ=15,18 were fitted to a hydrodynamic theory, which successfully models the density and temperature profiles away from the vibrating container bottom. A temperature inversion near the free upper surface is observed, in agreement with predictions based on the hydrodynamic parameter μ which is nonzero only in inelastic systems.

  4. NMR and mass spectrometry of phosphorus in wetlands

    Science.gov (United States)

    El-Rifai, H.; Heerboth, M.; Gedris, T.E.; Newman, S.; Orem, W.; Cooper, W.T.

    2008-01-01

    There is at present little information on the long-term stability of phosphorus sequestered in wetlands. Phosphorus sequestered during high loading periods may be relatively unstable and easily remobilized following changes in nutrient status or hydrological regime, but the chemical forms of sequestered phosphorus that do remobilize are largely unknown at this time. A lack of suitable analytical techniques has contributed to this dearth of knowledge regarding the stability of soil organic phosphorus. We analysed phosphorus in soils from the 'head' of Rescue Strand tree island and an adjacent marsh in the Florida Everglades by 31P nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry. Tree islands are important areas of biodiversity within the Everglades and offer a unique opportunity to study phosphorus sequestration because they are exposed to large phosphorus loads and appear to be natural nutrient sinks. The 31P NMR profiling of extracts from surface and sediment samples in the tree island indicates that phosphorus input to Rescue Strand tree island soils is mostly in the form of inorganic ortho-phosphate and is either refractory when deposited or rapidly recycled by the native vegetation into a stable phosphorus pool largely resistant to re-utilization by plants or microbes. Mass spectrometry revealed the presence of inositol hexakisphosphate, a common organic monophosphate ester not previously observed in Everglades' soils. ?? 2008 The Authors.

  5. Unique opportunities for NMR methods in structural genomics.

    Science.gov (United States)

    Montelione, Gaetano T; Arrowsmith, Cheryl; Girvin, Mark E; Kennedy, Michael A; Markley, John L; Powers, Robert; Prestegard, James H; Szyperski, Thomas

    2009-04-01

    This Perspective, arising from a workshop held in July 2008 in Buffalo NY, provides an overview of the role NMR has played in the United States Protein Structure Initiative (PSI), and a vision of how NMR will contribute to the forthcoming PSI-Biology program. NMR has contributed in key ways to structure production by the PSI, and new methods have been developed which are impacting the broader protein NMR community.

  6. Some exercises in quantitative NMR imaging

    International Nuclear Information System (INIS)

    Bakker, C.J.G.

    1985-01-01

    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 T 1 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 T 1 , 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 T 1 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.)

  7. Quantitative evaluation of experimental NMR restraints.

    NARCIS (Netherlands)

    Nabuurs, S.B.; Spronk, C.A.E.M.; Krieger, E.; Maassen, Hans; Vriend, G.; Vuister, G.W.

    2003-01-01

    Nuclear Overhauser effect (NOE) data are an indispensable source of structural information in biomolecular structure determination by NMR spectroscopy. The number and type of experimental restraints used in the structure calculation and the RMS deviation of the restraints are usually reported. We

  8. Quantification of complex mixtures by NMR

    NARCIS (Netherlands)

    Duynhoven, van J.P.M.; Velzen, van E.; Jacobs, D.M.

    2013-01-01

    NMR has firmly established itself as an analytical tool that can quantify analyte concentrations in complex mixtures in a rapid, cost-effective, accurate and precise manner. Here, the technological advances with respect to instrumentation, sample preparation, data acquisition and data processing

  9. NMR characterization of polymers: Review and update

    Science.gov (United States)

    NMR spectroscopy is a major technique for the characterization and analysis of polymers. A large number of methodologies have been developed in both the liquid and the solid state, and the literature has grown considerably (1-5). The field now covers a broad spectrum of activities, including polym...

  10. Structures of Biomolecules by NMR Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    GENERAL | ARTICLE integral part of NMR-based structural biology research. A num- ber of computational tools are being developed which utilize such information from BMRB and PDB at various stages of the structure determination process. 2. An Overview of the Structure Determination Process. A flowchart of the different ...

  11. 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.

  12. Structural Studies of Biological Solids Using NMR

    Science.gov (United States)

    Ramamoorthy, Ayyalusamy

    2011-03-01

    High-resolution structure and dynamics of biological molecules are important in understanding their function. While studies have been successful in solving the structures of water-soluble biomolecules, it has been proven difficult to determine the structures of membrane proteins and fibril systems. Recent studies have shown that solid-state NMR is a promising technique and could be highly valuable in studying such non-crystalline and non-soluble biosystems. I will present strategies to study the structures of such challenging systems and also about the applications of solid-state NMR to study the modes of membrane-peptide interactions for a better assessment of the prospects of antimicrobial peptides as substitutes to antibiotics in the control of human disease. Our studies on the mechanism of membrane disruption by LL-37 (a human antimicrobial peptide), analogs of the naturally occurring antimicrobial peptide magainin2 extracted from the skin of the African frog Xenopus Laevis, and pardaxin will be presented. Solid-state NMR experiments were used to determine the secondary structure, dynamics and topology of these peptides in lipid bilayers. Similarities and difference in the cell-lysing mechanism, and their dependence on the membrane composition, of these peptides will be discussed. Atomic-level resolution NMR structures of amyloidogenic proteins revealing the misfolding pathway and early intermediates that play key roles in amyloid toxicity will also be presented.

  13. Synthesis and NMR Elucidation of Novel Pentacycloundecane ...

    African Journals Online (AJOL)

    NICO

    2012-01-24

    Jan 24, 2012 ... research in this field, the NMR assignments of five PCU deriva- tives (1–5) ... macology.4,11 We have recently reported a family of PCU lactam .... These assignments are presented in Table 2. RESEARCH ARTICLE. R. Karpoormath, O.K. Onajole, T. Naicker, T. Govender, G.E.M. Maguire and H.G. Kruger.

  14. Advanced Laboratory NMR Spectrometer with Applications.

    Science.gov (United States)

    Biscegli, Clovis; And Others

    1982-01-01

    A description is given of an inexpensive nuclear magnetic resonance (NMR) spectrometer suitable for use in advanced laboratory courses. Applications to the nondestructive analysis of the oil content in corn seeds and in monitoring the crystallization of polymers are presented. (SK)

  15. NMR imaging of the cardiovascular system

    International Nuclear Information System (INIS)

    Canby, R.C.; Evanochko, W.T.; Pohost, G.M.

    1986-01-01

    Proton nuclear magnetic resonance (NMR) imaging permits high-resolution tomographic and three-dimensional images of the human body to be obtained without exposure to ionizing radiation. Such imaging not only yields anatomic resolution comparable to X-ray examinations but also provides a potential means to discriminate between healthy tissue and diseased tissue. This potential is based on certain NMR properties known as relaxation times, which determine, in part, the signal intensity in an image. These properties are related to such factors as the sizes and concentrations of proteins and mobile lipids and the compartmentalization of the protons of water. Although NMR imaging (also called magnetic resonance imaging, MRI) is becoming widely available for clinical use, application to the cardiovascular system, though promising, remains primarily a research tool. Gated proton NMR imaging can generate cardiac images with excellent morphologic detail and contrast; however, its ultimate importance as a cardiovascular diagnostic modality will depend on the development of several unique applications. These applications are discussed in this paper

  16. The bar coil for NMR tomograph

    International Nuclear Information System (INIS)

    Bogorodzki, P.; Piatkowski, A.; Wasielewski, J.

    1995-01-01

    The bar coil (bi-planar) for the NMR tomograph, designed for medical diagnostics, has been described. The tests of coil shown that it generates good homogenous magnetic field in a big volume what results in improving of the signal-to-noise ratio

  17. NMR blood vessel imaging method and apparatus

    International Nuclear Information System (INIS)

    Riederer, S.J.

    1988-01-01

    A high speed method of forming computed images of blood vessels based on measurements of characteristics of a body is described comprising the steps of: subjecting a predetermined body area containing blood vessels of interest to, successively, applications of a short repetition time (TR) NMR pulse sequence during the period of high blood velocity and then to corresponding applications during the period of low blood velocity for successive heart beat cycles; weighting the collected imaging data from each application of the NMR pulse sequence according to whether the data was acquired during the period of high blood velocity or a period of low blood velocity of the corresponding heart beat cycle; accumulating weighted imaging data from a plurality of NMR pulse sequences corresponding to high blood velocity periods and from a plurality of NMR pulse sequences corresponding to low blood velocity periods; subtracting the weighted imaging data corresponding to each specific phase encoding acquired during the high blood velocity periods from the weighted imaging data for the same phase encoding corresponding to low blood velocity periods in order to compute blood vessel imaging data; and forming an image of the blood vessels of interest from the blood vessel imaging data

  18. Theoretical molecular structure, vibrational frequencies and NMR ...

    African Journals Online (AJOL)

    Theoretical results have been successfully compared with available experimental data in the literature. Regarding the calculations, 2mpe-4bb prefers enol-imine form and DFT method is superior to HF approach except for predicting bond lengths. KEY WORDS: Schiff bases, Normal mode frequencies, HF, DFT, NMR. Bull.

  19. Recent Advances in Targeted and Untargeted Metabolomics by NMR and MS/NMR Methods

    Energy Technology Data Exchange (ETDEWEB)

    Bingol, Ahmet K.

    2018-04-18

    Metabolomics has made significant progress in multiple fronts in the last 18 months. This minireview aimed to give an overview of these advancements in the light of their contribution to targeted and untargeted metabolomics. New computational approaches have emerged to overcome manual absolute quantitation step of metabolites in 1D 1H NMR spectra. This provides more consistency between inter-laboratory comparisons. Integration of 2D NMR metabolomics databases under a unified web server allowed very accurate identification of the metabolites that have been catalogued in these databases. For the remaining uncatalogued and unknown metabolites, new cheminformatics approaches have been developed by combining NMR and mass spectrometry. These hybrid NMR/MS approaches accelerated the identification of unknowns in untargeted studies, and now they are allowing to profile ever larger number of metabolites in application studies.

  20. Petrophysical properties of greensand as predicted from NMR measurements

    DEFF Research Database (Denmark)

    Hossain, Zakir; Grattoni, Carlos A.; Solymar, Mikael

    2011-01-01

    ABSTRACT: Nuclear magnetic resonance (NMR) is a useful tool in reservoir evaluation. The objective of this study is to predict petrophysical properties from NMR T2 distributions. A series of laboratory experiments including core analysis, capillary pressure measurements, NMR T2 measurements and i...

  1. Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR

    International Nuclear Information System (INIS)

    Schot, Gijs van der; Bonvin, Alexandre M. J. J.

    2015-01-01

    We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on unassigned NOE lists (Huang et al. in J Am Chem Soc 127:1665–1674, 2005b, doi: 10.1021/ja047109h 10.1021/ja047109h ). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 with recalculated targets using the new R3FP fragment picker for fragment selection and implementing a new annotation of prediction reliability (van der Schot et al. in J Biomol NMR 57:27–35, 2013, doi: 10.1007/s10858-013-9762-6 10.1007/s10858-013-9762-6 ), both implemented in the CS-Rosetta3 WeNMR server. In this second round of CASD-NMR, the WeNMR CS-Rosetta server has demonstrated a much better performance than in the first round since only converged targets were submitted. Further, recalculation of all CASD-NMR targets using the new version of the server demonstrates that our new annotation of prediction quality is giving reliable results. Predictions annotated as weak are often found to provide useful models, but only for a fraction of the sequence, and should therefore only be used with caution

  2. Structural investigations on betacyanin pigments by LC NMR and 2D NMR spectroscopy.

    Science.gov (United States)

    Stintzing, Florian C; Conrad, Jürgen; Klaiber, Iris; Beifuss, Uwe; Carle, Reinhold

    2004-02-01

    Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was available. Because of its sufficient stability under highly acidic conditions otherwise detrimental for betacyanins, this pigment remained an exemption. Since betalains are most stable in the pH range of 5-7, a new solvent system has been developed allowing improved data acquisition through improved pigment stability at near neutral pH. Thus, not only (1)H, but for the first time also partial (13)C data of betanin, isobetanin, phyllocactin and hylocerenin isolated from red-purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose, Cactaceae] could be indirectly obtained by gHSQC- and gHMQC-NMR experiments.

  3. OPENCORE NMR: open-source core modules for implementing an integrated FPGA-based NMR spectrometer.

    Science.gov (United States)

    Takeda, Kazuyuki

    2008-06-01

    A tool kit for implementing an integrated FPGA-based NMR spectrometer [K. Takeda, A highly integrated FPGA-based nuclear magnetic resonance spectrometer, Rev. Sci. Instrum. 78 (2007) 033103], referred to as the OPENCORE NMR spectrometer, is open to public. The system is composed of an FPGA chip and several peripheral boards for USB communication, direct-digital synthesis (DDS), RF transmission, signal acquisition, etc. Inside the FPGA chip have been implemented a number of digital modules including three pulse programmers, the digital part of DDS, a digital quadrature demodulator, dual digital low-pass filters, and a PC interface. These FPGA core modules are written in VHDL, and their source codes are available on our website. This work aims at providing sufficient information with which one can, given some facility in circuit board manufacturing, reproduce the OPENCORE NMR spectrometer presented here. Also, the users are encouraged to modify the design of spectrometer according to their own specific needs. A home-built NMR spectrometer can serve complementary roles to a sophisticated commercial spectrometer, should one comes across such new ideas that require heavy modification to hardware inside the spectrometer. This work can lower the barrier of building a handmade NMR spectrometer in the laboratory, and promote novel and exciting NMR experiments.

  4. In situ solid-state NMR spectroscopy of electrochemical cells: batteries, supercapacitors, and fuel cells.

    Science.gov (United States)

    Blanc, Frédéric; Leskes, Michal; Grey, Clare P

    2013-09-17

    prevent dendrite formation. The in situ method was also applied to monitor (by (11)B NMR) electrochemical double-layer formation in supercapacitors in real time. Though this method is useful, it comes with challenges. The separation of the contributions from the different cell components in the NMR spectra is not trivial because of overlapping resonances. In addition, orientation-dependent NMR interactions, including the spatial- and orientation-dependent bulk magnetic susceptibility (BMS) effects, can lead to resonance broadening. Efforts to understand and mitigate these BMS effects are discussed in this Account. The in situ NMR investigation of fuel cells initially focused on the surface electrochemistry at the electrodes and the electrochemical oxidation of methanol and CO to CO2 on the Pt cathode. On the basis of the (13)C and (195)Pt NMR spectra of the adsorbates and electrodes, CO adsorbed on Pt and other reaction intermediates and complete oxidation products were detected and their mode of binding to the electrodes investigated. Appropriate design and engineering of the NMR hardware has allowed researchers to integrate intact direct methanol fuel cells into NMR probes. Chemical transformations of the circulating methanol could be followed and reaction intermediates could be detected in real time by either (2)H or (13)C NMR spectroscopy. By use of the in situ NMR approach, factors that control fuel cell performance, such as methanol cross over and catalyst performance, were identified.

  5. Relation Between Acid and Catalytic Properties of Chlorinated Gamma-Alumina. a 31p Mas Nmr and Ftir Investigation

    Directory of Open Access Journals (Sweden)

    Guillaume D.

    1999-07-01

    Full Text Available In this paper, we have studied the effect of chlorine on the surface properties of gamma-alumina, especially on their acid properties. The use of FTIR spectroscopy and 31P MAS NMR of adsorbed trimethylphosphine allows to propose a chlorination mechanism. To correlate the surface properties of these chlorinated gamma-alumina with their catalytic properties, we have used a model reaction, the cracking of n-heptane under reforming conditions. The analysis of the correlation between acid properties determined by 31P MAS NMR and the catalytic results (in terms of activities and selectivities allows to identify which sites are involved in the cracking reaction.

  6. A 1H NMR spectroscopic study on the tryptophan residues of lysozyme included by glucosyl-β-cyclodextrin

    Science.gov (United States)

    Yamamoto, Tatsuyuki; Kobayashi, Teruya; Yoshikiyo, Keisuke; Matsui, Yoshihisa; Takahashi, Tetsuya; Aso, Yuji

    2009-02-01

    A 1H NMR spectroscopic study showed that the side chains of Trp residues of chicken egg white lysozyme in an aqueous solution are included by Glucosyl-β-cyclodextrin (G1-β-CD). The 1H NMR signals due to Trp residues shifted with the addition of G1-β-CD. The addition of methyl α- D-glucopyranoside, which has no inclusion ability, gave different effect on the shift of 1H NMR signals. The 1H NMR signals due to Cys64 and Ile98 were also influenced to a considerable extent with the addition of G1-β-CD, suggesting that these hydrophobic amino acid residues are also included by the CD. The chemical shift values of 1H NMR signals, due to indole rings of tryptophan residues, changed more with the addition of G1-β-CD. The magnitudes of the chemical shift change were different depending on their locations in the protein. The chemical shift values of 1H NMR signals, due to those Trp residues in the active site of the lysozyme were smaller than those locating at relatively near the surface of the protein.

  7. Solid-state NMR basic principles and practice

    CERN Document Server

    Apperley, David C; Hodgkinson, Paul

    2014-01-01

    Nuclear Magnetic Resonance (NMR) has proved to be a uniquely powerful and versatile tool for analyzing and characterizing chemicals and materials of all kinds. This book focuses on the latest developments and applications for "solid-state" NMR, which has found new uses from archaeology to crystallography to biomaterials and pharmaceutical science research. The book will provide materials engineers, analytical chemists, and physicists, in and out of lab, a survey of the techniques and the essential tools of solid-state NMR, together with a practical guide on applications. In this concise introduction to the growing field of solid-state nuclear magnetic resonance spectroscopy The reader will find: * Basic NMR concepts for solids, including guidance on the spin-1/2 nuclei concept * Coverage of the quantum mechanics aspects of solid state NMR and an introduction to the concept of quadrupolar nuclei * An understanding relaxation, exchange and quantitation in NMR * An analysis and interpretation of NMR data, with e...

  8. NMR shielding calculations across the periodic table: diamagnetic uranium compounds. 2. Ligand and metal NMR.

    Science.gov (United States)

    Schreckenbach, Georg

    2002-12-16

    In this and a previous article (J. Phys. Chem. A 2000, 104, 8244), the range of application for relativistic density functional theory (DFT) is extended to the calculation of nuclear magnetic resonance (NMR) shieldings and chemical shifts in diamagnetic actinide compounds. Two relativistic DFT methods are used, ZORA ("zeroth-order regular approximation") and the quasirelativistic (QR) method. In the given second paper, NMR shieldings and chemical shifts are calculated and discussed for a wide range of compounds. The molecules studied comprise uranyl complexes, [UO(2)L(n)](+/-)(q); UF(6); inorganic UF(6) derivatives, UF(6-n)Cl(n), n = 0-6; and organometallic UF(6) derivatives, UF(6-n)(OCH(3))(n), n = 0-5. Uranyl complexes include [UO(2)F(4)](2-), [UO(2)Cl(4)](2-), [UO(2)(OH)(4)](2-), [UO(2)(CO(3))(3)](4-), and [UO(2)(H(2)O)(5)](2+). For the ligand NMR, moderate (e.g., (19)F NMR chemical shifts in UF(6-n)Cl(n)) to excellent agreement [e.g., (19)F chemical shift tensor in UF(6) or (1)H NMR in UF(6-n)(OCH(3))(n)] has been found between theory and experiment. The methods have been used to calculate the experimentally unknown (235)U NMR chemical shifts. A large chemical shift range of at least 21,000 ppm has been predicted for the (235)U nucleus. ZORA spin-orbit appears to be the most accurate method for predicting actinide metal chemical shifts. Trends in the (235)U NMR chemical shifts of UF(6-n)L(n) molecules are analyzed and explained in terms of the calculated electronic structure. It is argued that the energy separation and interaction between occupied and virtual orbitals with f-character are the determining factors.

  9. Unilateral NMR, 13C CPMAS NMR spectroscopy and micro-analytical techniques for studying the materials and state of conservation of an ancient Egyptian wooden sarcophagus.

    Science.gov (United States)

    Proietti, Noemi; Presciutti, Federica; Di Tullio, Valeria; Doherty, Brenda; Marinelli, Anna Maria; Provinciali, Barbara; Macchioni, Nicola; Capitani, Donatella; Miliani, Costanza

    2011-03-01

    A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV-XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix. This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood and the presence of organic substances by (13)C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical microscopy (OM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Raman and surface enhanced (resonance) Raman spectroscopy (SERS/SERRS), infrared and GC-MS techniques, evidencing original components such as clay minerals, Egyptian green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy.

  10. Some nitrogen-14 NMR studies in solids

    Energy Technology Data Exchange (ETDEWEB)

    Pratum, T.K.

    1983-11-01

    The first order quadrupolar perturbation of the /sup 14/N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long /sup 14/N longitudinal relaxation times (T/sub 1/) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between /sup 14/N and /sup 1/H. Using quadrupolar echo and CP techniques, the /sup 14/N quadrupolar coupling constants (e/sup 2/qQ/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 /sup 14/N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects.

  11. Fully automated system for pulsed NMR measurements

    International Nuclear Information System (INIS)

    Cantor, D.M.

    1977-01-01

    A system is described which places many of the complex, tedious operations for pulsed NMR experiments under computer control. It automatically optimizes the experiment parameters of pulse length and phase, and precision, accuracy, and measurement speed are improved. The hardware interface between the computer and the NMR instrument is described. Design features, justification of the choices made between alternative design strategies, and details of the implementation of design goals are presented. Software features common to all the available experiments are discussed. Optimization of pulse lengths and phases is performed via a sequential search technique called Uniplex. Measurements of the spin-lattice and spin-spin relaxation times and of diffusion constants are automatic. Options for expansion of the system are explored along with some of the limitations of the system

  12. Some nitrogen-14 NMR studies in solids

    International Nuclear Information System (INIS)

    Pratum, T.K.

    1983-11-01

    The first order quadrupolar perturbation of the 14 N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long 14 N longitudinal relaxation times (T 1 ) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between 14 N and 1 H. Using quadrupolar echo and CP techniques, the 14 N quadrupolar coupling constants (e 2 qQ/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 14 N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects

  13. {beta}-nmr of Palladium foil

    Energy Technology Data Exchange (ETDEWEB)

    Parolin, T.J. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Salman, Z. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Chakhalian, J. [Max-Plank Institute for Solid State Research, D-70569 Stuttgart (Germany); Wang, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Keeler, T.A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Hossain, Md. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Kiefl, R.F. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Canadian Institute for Advanced Research (Canada); Chow, K.H. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2J1 (Canada); Morris, G.D. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Miller, R.I. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); MacFarlane, W.A. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)]. E-mail: wam@chem.ubc.ca

    2006-03-31

    Beta-detected NMR ({beta}-nmr) of low-energy implanted {sup 8}Li{sup +} was studied in metallic palladium. The resonance was found to have a large negative shift with respect to the reference signal in the cubic insulator MgO. This shift exhibited significant temperature dependence on cooling below room temperature, approximately proportionate to the temperature-dependent spin susceptibility of pure Pd. Thus it is tentatively attributed to a Knight shift (K) caused by a large negative hyperfine coupling; a phenomenon common in transition metal ions, but not in alkalis. However, the spin-lattice relaxation of {sup 8}Li is much slower than expected from the Korringa law for such a large K. We compare results from samples of very different thicknesses: 12.5{mu}m foil and a 100nm thin film.

  14. DNA oligonucleotide conformations: high resolution NMR studies

    International Nuclear Information System (INIS)

    Mellema, J.-R.

    1984-01-01

    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 1 H 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 1 H NMR spectrum of a DNA tetramer, d(TAAT). Preliminary conformational data derived from the spectral parameters recorded at 27 0 C are given. A more detailed analysis employing temperature-dependence studies is given in Chapter 4. (Auth.)

  15. NMR Fingerprints of Eucommia ulmoides Oliver

    Directory of Open Access Journals (Sweden)

    JIANG Yang-ming

    2017-12-01

    Full Text Available The 1H NMR fingerprint of Eucommia ulmoides acquired with a CPMG pulse sequence was analyzed with the complete reduction to amplitude-frequency table (CRAFT approach. The signals of target compounds were extracted without chemical separation and purification. Quantitative analysis showed that the average concentration of pinoresinol glucoside (PDG in Eucommia ulmoides got from Guiyang medical plant garden was 0.275 6% with a relative standard deviation (RSD of 1.69%. The results were consistent with those obtained by high performance liquid chromatography (average content of 0.269 6% and RSD of 0.65%. NMR fingerprint and multivariate statistical analysis also revealed that there existed significant differences between Hunan and Guizhou Eucommia ulmoides Oliver.

  16. Exploring the limits to spatially resolved NMR

    Energy Technology Data Exchange (ETDEWEB)

    Gaedke, Achim; Nestle, Nikolaus [TU Darmstadt, Institute of Condensed Matter Physics (Germany)

    2010-07-01

    Recent advances in MRI have demonstrated resolutions down to 1 {mu}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.

  17. Quantitative calibration of radiofrequency NMR Stark effects.

    Science.gov (United States)

    Tarasek, Matthew R; Kempf, James G

    2011-10-01

    Nuclear magnetic resonance (NMR) Stark responses can occur in quadrupolar nuclei for an electric field oscillating at twice the usual NMR frequency (2ω(0)). Calibration of responses to an applied E field is needed to establish nuclear spins as probes of native E fields within material and molecular systems. We present an improved approach and apparatus for accurate measurement of quadrupolar Stark effects. Updated values of C(14) (the response parameter in cubic crystals) were obtained for both (69)Ga and (75)As in GaAs. Keys to improvement include a modified implementation of voltage dividers to assess the 2ω(0) amplitude, |E|, and the stabilization of divider response by reduction of stray couplings in 2ω(0) circuitry. Finally, accuracy was enhanced by filtering sets of |E| through a linear response function that we established for the radiofrequency amplifier. Our approach is verified by two types of spectral results. Steady-state 2ω(0) excitation to presaturate NMR spectra yielded C(14) = (2.59 ± 0.06) × 10(12) m(-1) for (69)Ga at room-temperature and 14.1 T. For (75)As, we obtained (3.1 ± 0.1) × 10(12) m(-1). Both values reconcile with earlier results from 77 K and below 1 T, whereas current experiments are at room temperature and 14.1 T. Finally, we present results where few-microsecond pulses of the 2ω(0) field induced small (tens of Hz) changes in high-resolution NMR line shapes. There too, spectra collected vs |E| agree with the model for response, further establishing the validity of our protocols to specify |E|.

  18. NMR of 1,2-dioxiquinolines

    International Nuclear Information System (INIS)

    Figueroa Villar, Jose Daniel; Santos, N.L. dos

    1993-01-01

    Several derivates of quinoline are known for presenting pharmacological activity as antibiotics and anti-parasites, from which an important group are the antibiotics for the treatment of malaria and infections of the urinary tract. This work presents the structures and the NMR spectra of three new derivates of quinoline. These compounds are being tested as possible antibiotics for the treatment of urinary infections caused by Escherichia coli which are extremely resistant to other types of antibiotics

  19. NMR dispersion measurement of dynamic nuclear polarization

    International Nuclear Information System (INIS)

    Davies, K.; Cox, S.F.J.

    1978-01-01

    The feasibility of monitoring dynamic nuclear polarization from the NMR dispersive susceptibility is examined. Two prototype instruments are tested in a polarized proton target using organic target material. The more promising employs a tunnel diode oscillator, inside the target cavity, and should provide a precise polarization measurement working at a frequency far enough from the main resonance for the disturbance of the measured polarization to be negligible. Other existing methods for measuring target polarization are briefly reviewed. (author)

  20. Structure of high-resolution NMR spectra

    CERN Document Server

    Corio, PL

    2012-01-01

    Structure of High-Resolution NMR Spectra provides the principles, theories, and mathematical and physical concepts of high-resolution nuclear magnetic resonance spectra.The book presents the elementary theory of magnetic resonance; the quantum mechanical theory of angular momentum; the general theory of steady state spectra; and multiple quantum transitions, double resonance and spin echo experiments.Physicists, chemists, and researchers will find the book a valuable reference text.

  1. 3D Reconstruction of NMR Images

    Directory of Open Access Journals (Sweden)

    Peter Izak

    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.

  2. observed by high pressure NMR and NQR

    Indian Academy of Sciences (India)

    Department of Material Science, Himeji Institute of Technology, Kamigori,. Akogun, Hyogo 678-1297, Japan. ∗. Email: kohara@sci.himeji tech.ac.jp. Abstract. NMR and NQR studies on two interesting systems (URu2Si2, CeTIn5) were performed under high pressure. (1) URu2Si2: In the pressure range 3.0 to 8.3 kbar, we ...

  3. Comparison of NMR and crystal structures highlights conformational isomerism in protein active sites

    International Nuclear Information System (INIS)

    Serrano, Pedro; Pedrini, Bill; Geralt, Michael; Jaudzems, Kristaps; Mohanty, Biswaranjan; Horst, Reto; Herrmann, Torsten; Elsliger, Marc-André; Wilson, Ian A.; Wüthrich, Kurt

    2010-01-01

    Tools for systematic comparisons of NMR and crystal structures developed by the JCSG were applied to two proteins with known functions: the T. maritima anti-σ factor antagonist TM1081 and the mouse γ-glutamylamine cyclotransferase A2LD1 (gi:13879369). In an attempt to exploit the complementarity of crystal and NMR data, the combined use of the two structure-determination techniques was explored for the initial steps in the challenge of searching proteins of unknown functions for putative active sites. The JCSG has recently developed a protocol for systematic comparisons of high-quality crystal and NMR structures of proteins. In this paper, the extent to which this approach can provide function-related information on the two functionally annotated proteins TM1081, a Thermotoga maritima anti-σ factor antagonist, and A2LD1 (gi:13879369), a mouse γ-glutamylamine cyclotransferase, is explored. The NMR structures of the two proteins have been determined in solution at 313 and 298 K, respectively, using the current JCSG protocol based on the software package UNIO for extensive automation. The corresponding crystal structures were solved by the JCSG at 100 K and 1.6 Å resolution and at 100 K and 1.9 Å resolution, respectively. The NMR and crystal structures of the two proteins share the same overall molecular architectures. However, the precision of the structure determination along the amino-acid sequence varies over a significantly wider range in the NMR structures than in the crystal structures. Thereby, in each of the two NMR structures about 65% of the residues have displacements below the average and in both proteins the less well ordered residues include large parts of the active sites, in addition to some highly solvent-exposed surface areas. Whereas the latter show increased disorder in the crystal and in solution, the active-site regions display increased displacements only in the NMR structures, where they undergo local conformational exchange on the

  4. NMR detects molecular interactions of graphene with aromatic and aliphatic hydrocarbons in water

    Science.gov (United States)

    Bichenkova, Elena V.; Raju, Arun P. A.; Burusco, Kepa K.; Kinloch, Ian A.; Novoselov, Kostya S.; Clarke, David J.

    2018-03-01

    Polyaromatic carbon is widely held to be strongly diamagnetic and hydrophobic, with textbook van der Waals and ‘π-stacked’ binding of hydrocarbons, which disrupt their self-assembled supramolecular structures. The NMR of organic molecules sequestered by polyaromatic carbon is expected to be dominated by shielding from the orbital diamagnetism of π electrons. We report the first evidence of very different polar and magnetic behavior in water, wherein graphene remained well-dispersed after extensive dialysis and behaved as a 1H-NMR-silent ghost. Magnetic effects dominated the NMR of organic structures which interacted with graphene, with changes in spin-spin coupling, vast increase in relaxation, line broadening and decrease in NMR peak heights when bound to graphene. However, the interactions were weak, reversible and did not disrupt organic self-assemblies reliant on hydrophobic ‘π-stacking’, even when substantially sequestered on the surface of graphene by the high surface area available. Interacting assemblies of aromatic molecules retained their strongly-shielded NMR signals and remained within self-assembled structures, with slower rates of diffusion from association with graphene, but with no further shielding from graphene. Binding to graphene was selective for positively-charged organic assemblies, weaker for non-aromatic and negligible for strongly-negatively-charged molecules, presumably repelled by a negative zeta potential of graphene in water. Stronger binders, or considerable excess of weaker binders readily reversed physisorption, with no evidence of structural changes from chemisorption. The fundamental nature of these different electronic interactions between organic and polyaromatic carbon is considered with relevance to electronics, charge storage, sensor, medical, pharmaceutical and environmental research.

  5. Comparison of soil organic carbon speciation using C NEXAFS and CPMAS 13C NMR spectroscopy.

    Science.gov (United States)

    Prietzel, Jörg; Müller, Svenja; Kögel-Knabner, Ingrid; Thieme, Jürgen; Jaye, Cherno; Fischer, Daniel

    2018-07-01

    We compared synchrotron-based C near-edge X-ray absorption fine structure (NEXAFS) and CPMAS 13 C nuclear magnetic resonance (NMR) spectroscopy with respect to their precision and accuracy to quantify different organic carbon (OC) species in defined mixtures of soil organic matter source compounds. We also used both methods to quantify different OC species in organic surface horizons of a Histic Leptosol as well as in mineral topsoil and subsoil horizons of two soils with different parent material, stage of pedogenesis, and OC content (Cambisol: 15-30 OC mgg -1 , Podzol: 0.9-7 OC mgg -1 ). CPMAS 13 C NMR spectroscopy was more accurate and precise (mean recovery of different C functional groups 96-103%) than C NEXAFS spectroscopy (mean recovery 92-113%). For organic surface and topsoil samples, NMR spectroscopy consistently yielded larger O-alkyl C percentages and smaller alkyl C percentages than C NEXAFS spectroscopy. For the Cambisol subsoil samples both methods performed well and showed similar C speciation results. NEXAFS spectroscopy yielded excellent spectra with a high signal-to-noise ratio also for OC-poor Podzol subsoil samples, whereas this was not the case for CPMAS 13 C NMR spectroscopy even after sample treatment with HF. Our results confirm the analytical power of CPMAS 13 C NMR spectroscopy for a reliable quantitative OC speciation in soils with >10mgOCg -1 . Moreover, they highlight the potential of synchrotron-based C NEXAFS spectroscopy as fast, non-invasive method to semi-quantify different C functional groups in soils with low C content (0.9-10mgg -1 ). Copyright © 2018 Elsevier B.V. All rights reserved.

  6. NMR methodologies for studying mitochondrial bioenergetics.

    Science.gov (United States)

    Alves, Tiago C; Jarak, Ivana; Carvalho, Rui A

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is a technique with an increasing importance in the study of metabolic diseases. Its initial important role in the determination of chemical structures (1, 2) has been considerably overcome by its potential for the in vivo study of metabolism (3-5). The main characteristic that makes this technique so attractive is its noninvasiveness. Only nuclei capable of transitioning between energy states, in the presence of an intense and constant magnetic field, are studied. This includes abundant nuclei such as proton ((1)H) and phosphorous ((31)P), as well as stable isotopes such as deuterium ((2)H) and carbon 13 ((13)C). This allows a wide range of applications that vary from the determination of water distribution in tissues (as obtained in a magnetic resonance imaging scan) to the calculation of metabolic fluxes under ex vivo and in vivo conditions without the need to use radioactive tracers or tissue biopsies (as in a magnetic resonance spectroscopy (MRS) scan). In this chapter, some technical aspects of the methodology of an NMR/MRS experiment as well as how it can be used to study mitochondrial bioenergetics are overviewed. Advantages and disadvantages of in vivo MRS versus high-resolution NMR using proton high rotation magic angle spinning (HRMAS) of tissue biopsies and tissue extracts are also discussed.

  7. 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...

  8. Solid state NMR study of cumbaru flour

    International Nuclear Information System (INIS)

    Nogueira, Jose S.; Bathista, Andre L.B.S.; Silva, Emerson O.; Priante Filho, Nicolau; Tavares, Maria I.B.

    2001-01-01

    The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13 C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T 1 H ρ). 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 13 C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13 C 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 13 C decays, which give us more information about sample heterogeneity. The T 1 H ρHr 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)

  9. Multispectral dual isotope and NMR image analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vannier, M.W.; Beihn, R.M.; Butterfield, R.L.; De Land, F.H.

    1985-05-01

    Dual isotope scintigraphy and nuclear magnetic resonance imaging produce image data that is intrinsically multispectral. That is multiple images of the same anatomic region are generated with different gray scale distribution and morphologic content that is largely redundant. Image processing technology, originally developed by NASA for satellite imaging, is available for multispectral analysis. These methods have been applied to provide tissue characterization. Tissue specific information encoded in the grapy scale data from dual isotope and NMR studies may be extracted using multispectral pattern recognition methods. The authors used table lookup minimum distance, maximum likelihood and cluster analysis techniques with data sets from Ga-67 / Tc-99m, 1-131 labeled antibodies / Tc-99m, Tc-99m perfusion / Xe-133 ventilation, and NMR studies. The results show; tissue characteristic signatures exist in dual isotope and NMR imaging, and these spectral signatures are identifiable using multispectral image analysis and provide tissue classification maps with scatter diagrams that facilitate interpretation and assist in elucidating subtle changes.

  10. Protein NMR structures refined without NOE data.

    Science.gov (United States)

    Ryu, Hyojung; Kim, Tae-Rae; Ahn, SeonJoo; Ji, Sunyoung; Lee, Jinhyuk

    2014-01-01

    The refinement of low-quality structures is an important challenge in protein structure prediction. Many studies have been conducted on protein structure refinement; the refinement of structures derived from NMR spectroscopy has been especially intensively studied. In this study, we generated flat-bottom distance potential instead of NOE data because NOE data have ambiguity and uncertainty. The potential was derived from distance information from given structures and prevented structural dislocation during the refinement process. A simulated annealing protocol was used to minimize the potential energy of the structure. The protocol was tested on 134 NMR structures in the Protein Data Bank (PDB) that also have X-ray structures. Among them, 50 structures were used as a training set to find the optimal "width" parameter in the flat-bottom distance potential functions. In the validation set (the other 84 structures), most of the 12 quality assessment scores of the refined structures were significantly improved (total score increased from 1.215 to 2.044). Moreover, the secondary structure similarity of the refined structure was improved over that of the original structure. Finally, we demonstrate that the combination of two energy potentials, statistical torsion angle potential (STAP) and the flat-bottom distance potential, can drive the refinement of NMR structures.

  11. CcpNmr AnalysisAssign: a flexible platform for integrated NMR analysis

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Simon P.; Fogh, Rasmus H. [University of Leicester, Department of Molecular and Cell Biology, Leicester Institute for Structural- and Chemical Biology (United Kingdom); Boucher, Wayne [University of Cambridge, Department of Biochemistry (United Kingdom); Ragan, Timothy J.; Mureddu, Luca G.; Vuister, Geerten W., E-mail: gv29@le.ac.uk [University of Leicester, Department of Molecular and Cell Biology, Leicester Institute for Structural- and Chemical Biology (United Kingdom)

    2016-10-15

    NMR spectroscopy is an indispensably powerful technique for the analysis of biomolecules under ambient conditions, both for structural- and functional studies. However, in practice the complexity of the technique has often frustrated its application by non-specialists. In this paper, we present CcpNmr version-3, the latest software release from the Collaborative Computational Project for NMR, for all aspects of NMR data analysis, including liquid- and solid-state NMR data. This software has been designed to be simple, functional and flexible, and aims to ensure that routine tasks can be performed in a straightforward manner. We have designed the software according to modern software engineering principles and leveraged the capabilities of modern graphics libraries to simplify a variety of data analysis tasks. We describe the process of backbone assignment as an example of the flexibility and simplicity of implementing workflows, as well as the toolkit used to create the necessary graphics for this workflow. The package can be downloaded from www.ccpn.ac.uk/v3-software/downloads http://www.ccpn.ac.uk/v3-software/downloads and is freely available to all non-profit organisations.

  12. Guiding automated NMR structure determination using a global optimization metric, the NMR DP score

    International Nuclear Information System (INIS)

    Huang, Yuanpeng Janet; Mao, Binchen; Xu, Fei; Montelione, Gaetano T.

    2015-01-01

    ASDP is an automated NMR NOE assignment program. It uses a distinct bottom-up topology-constrained network anchoring approach for NOE interpretation, with 2D, 3D and/or 4D NOESY peak lists and resonance assignments as input, and generates unambiguous NOE constraints for iterative structure calculations. ASDP is designed to function interactively with various structure determination programs that use distance restraints to generate molecular models. In the CASD–NMR project, ASDP was tested and further developed using blinded NMR data, including resonance assignments, either raw or manually-curated (refined) NOESY peak list data, and in some cases 15 N– 1 H residual dipolar coupling data. In these blinded tests, in which the reference structure was not available until after structures were generated, the fully-automated ASDP program performed very well on all targets using both the raw and refined NOESY peak list data. Improvements of ASDP relative to its predecessor program for automated NOESY peak assignments, AutoStructure, were driven by challenges provided by these CASD–NMR data. These algorithmic improvements include (1) using a global metric of structural accuracy, the discriminating power score, for guiding model selection during the iterative NOE interpretation process, and (2) identifying incorrect NOESY cross peak assignments caused by errors in the NMR resonance assignment list. These improvements provide a more robust automated NOESY analysis program, ASDP, with the unique capability of being utilized with alternative structure generation and refinement programs including CYANA, CNS, and/or Rosetta

  13. Molecular Mobility of the Interface in a Model Composite: A NMR Study

    Science.gov (United States)

    1992-07-15

    phenylene ) bismaleimide (BMI), was obtained from Aldrich and used as received. Curing reactions were carried out in a crucible by heating at 185 ’C for...coupling agents onto silica surfaces and the interaction of these functional silanes with a bismaleimide resin was studied. Carbon-13 CP/MAS NMR was used to...confirm the bonding between the silane and bismaleimide (BMI) resin and elucidate the nature of the crosslinking reaction of BMI. Deuterated coupling

  14. Well-defined azazirconacyclopropane complexes supported on silica structurally determined by 2D NMR comparative elucidation

    KAUST Repository

    El Eter, Mohamad

    2013-01-01

    Grafting of Zr(NMe2)4 on mesoporous silica SBA-15 afforded selectively well-defined surface species SiOZr(NMe2) (η2NMeCH2). 2D solid-state NMR (1H- 13C HETCOR, Multiple Quantum) experiments have shown a unique structural rearrangement occurring on the immobilised zirconium bis methylamido ligand. © The Royal Society of Chemistry 2013.

  15. NMR Detection of Semi-Specific Antibody Interactions in Serum Environments

    Directory of Open Access Journals (Sweden)

    Saeko Yanaka

    2017-09-01

    Full Text Available Although antibody functions are executed in heterogeneous blood streams characterized by molecular crowding and promiscuous intermolecular interaction, detailed structural characterizations of antibody interactions have thus far been performed under homogeneous in vitro conditions. NMR spectroscopy potentially has the ability to study protein structures in heterogeneous environments, assuming that the target protein can be labeled with NMR-active isotopes. Based on our successful development of isotope labeling of antibody glycoproteins, here we apply NMR spectroscopy to characterize antibody interactions in heterogeneous extracellular environments using mouse IgG-Fc as a test molecule. In human serum, many of the HSQC peaks originating from the Fc backbone exhibited attenuation in intensity of various magnitudes. Similar spectral changes were induced by the Fab fragment of polyclonal IgG isolated from the serum, but not by serum albumin, indicating that a subset of antibodies reactive with mouse IgG-Fc exists in human serum without preimmunization. The metaepitopes recognized by serum polyclonal IgG cover the entire molecular surface of Fc, including the binding sites to Fc receptors and C1q. In-serum NMR observation will offer useful tools for the detailed characterization of biopharamaceuticals, including therapeutic antibodies in physiologically relevant heterogeneous environments, also giving deeper insight into molecular recognition by polyclonal antibodies in the immune system.

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

    International Nuclear Information System (INIS)

    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

  17. 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.

  18. Portable microcoil NMR detection coupled to capillary electrophoresis.

    Science.gov (United States)

    Diekmann, Joana; Adams, Kristl L; Klunder, Gregory L; Evans, Lee; Steele, Paul; Vogt, Carla; Herberg, Julie L

    2011-02-15

    High-efficiency separation techniques, such as capillary electrophoresis (CE), coupled to a nondestructive nuclear magnetic resonance (NMR) spectrometer offer the ability to separate, chemically identify, and provide structural information on analytes in small sample volumes. Previous CE-NMR coupled systems utilized laboratory-scale NMR magnets and spectrometers, which require very long separation capillaries. New technological developments in electronics have reduced the size of the NMR system, and small 1-2 T permanent magnets provide the possibilities of a truly portable NMR. The microcoils used in portable and laboratory-scale NMR may offer the advantage of improved mass sensitivity because the limit of detection (LOD) is proportional to the coil diameter. In this work, CE is coupled with a portable, briefcase-sized NMR system that incorporates a microcoil probe and a 1.8 T permanent magnet to measure (19)F NMR spectra. Separations of fluorinated molecules are demonstrated with stopped- and continuous-flow NMR detection. The results demonstrate that coupling CE to a portable NMR instrument is feasible and can provide a low-cost method to obtain structural information on microliter samples. An LOD of 31.8 nmol for perfluorotributylamine with a resolution of 4 ppm has been achieved with this system.

  19. Solid-state NMR paramagnetic relaxation enhancement immersion depth studies in phospholipid bilayers

    KAUST Repository

    Chu, Shidong

    2010-11-01

    A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine (PSPC) phospholipid bilayers as paramagnetic moieties and the resulting enhancements of the longitudinal relaxation (T1) times of 31P nuclei on the surface of the bilayers were measured by a standard inversion recovery pulse sequence. The 31P NMR spin-lattice relaxation times decrease steadily as the DOXYL spin label moves closer to the surface as well as the concentration of the spin-labeled lipids increase. The enhanced relaxation vs. the position and concentration of spin-labels indicate that PRE induced by the DOXYL spin label are significant to determine longer distances over the whole range of the membrane depths. When these data were combined with estimated correlation times τc, the r-6-weighted, time-averaged distances between the spin-labels and the 31P nuclei on the membrane surface were estimated. The application of using this solid-state NMR PRE approach coupled with site-directed spin labeling (SDSL) may be a powerful method for measuring membrane protein immersion depth. © 2010 Elsevier Inc. All rights reserved.

  20. Knowns and unknowns in metabolomics identified by multidimensional NMR and hybrid MS/NMR methods

    Energy Technology Data Exchange (ETDEWEB)

    Bingol, Kerem; Brüschweiler, Rafael

    2017-02-01

    Metabolomics continues to make rapid progress through the development of new and better methods and their applications to gain insight into the metabolism of a wide range of different biological systems from a systems biology perspective. Customization of NMR databases and search tools allows the faster and more accurate identification of known metabolites, whereas the identification of unknowns, without a need for extensive purification, requires new strategies to integrate NMR with mass spectrometry, cheminformatics, and computational methods. For some applications, the use of covalent and non-covalent attachments in the form of labeled tags or nanoparticles can significantly reduce the complexity of these tasks.

  1. NMR Studies of Protein Hydration and Protein-Ligand Interactions

    Science.gov (United States)

    Chong, Yuan

    Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

  2. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Quantitative nuclear magnetic resonance (qNMR is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR and only a few fluorine qNMR (19F qNMR were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes.

  3. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

    Science.gov (United States)

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes. PMID:27688925

  4. Direct Comparison of (19)F qNMR and (1)H qNMR by Characterizing Atorvastatin Calcium Content.

    Science.gov (United States)

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin; He, Lan

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR ((1)H qNMR) and only a few fluorine qNMR ((19)F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both (19)F and (1)H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that (19)F qNMR has similar precision and sensitivity to (1)H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from (19)F qNMR is that the analyte signal is with less or no interference from impurities. (19)F qNMR is an excellent approach to quantify fluorine-containing analytes.

  5. Two dimensional NMR of liquids and oriented molecules

    Energy Technology Data Exchange (ETDEWEB)

    Gochin, M.

    1987-02-01

    Chapter 1 discusses the quantum mechanical formalism used for describing the interaction between magnetic dipoles that dictates the appearance of a spectrum. The NMR characteristics of liquids and liquid crystals are stressed. Chapter 2 reviews the theory of multiple quantum and two dimensional NMR. Properties of typical spectra and phase cycling procedures are discussed. Chapter 3 describes a specific application of heteronuclear double quantum coherence to the removal of inhomogeneous broadening in liquids. Pulse sequences have been devised which cancel out any contribution from this inhomogeneity to the final spectrum. An interpretation of various pulse sequences for the case of /sup 13/C and /sup 1/H is given, together with methods of spectral editing by removal or retention of the homo- or heteronuclear J coupling. The technique is applied to a demonstration of high resolution in both frequency and spatial dimensions with a surface coil. In Chapter 4, multiple quantum filtered 2-D spectroscopy is demonstrated as an effective means of studying randomly deuterated molecules dissolved in a nematic liquid crystal. Magnitudes of dipole coupling constants have been determined for benzene and hexane, and their signs and assignments found from high order multiple quantum spectra. For the first time, a realistic impression of the conformation of hexane can be estimated from these results. Chapter 5 is a technical description of the MDB DCHIB-DR11W parallel interface which has been set up to transfer data between the Data General Nova 820 minicomputer, interfaced to the 360 MHz spectrometer, and the Vax 11/730. It covers operation of the boards, physical specifications and installation, and programs for testing and running the interface.

  6. Two dimensional NMR of liquids and oriented molecules

    International Nuclear Information System (INIS)

    Gochin, M.

    1987-02-01

    Chapter 1 discusses the quantum mechanical formalism used for describing the interaction between magnetic dipoles that dictates the appearance of a spectrum. The NMR characteristics of liquids and liquid crystals are stressed. Chapter 2 reviews the theory of multiple quantum and two dimensional NMR. Properties of typical spectra and phase cycling procedures are discussed. Chapter 3 describes a specific application of heteronuclear double quantum coherence to the removal of inhomogeneous broadening in liquids. Pulse sequences have been devised which cancel out any contribution from this inhomogeneity to the final spectrum. An interpretation of various pulse sequences for the case of 13 C and 1 H is given, together with methods of spectral editing by removal or retention of the homo- or heteronuclear J coupling. The technique is applied to a demonstration of high resolution in both frequency and spatial dimensions with a surface coil. In Chapter 4, multiple quantum filtered 2-D spectroscopy is demonstrated as an effective means of studying randomly deuterated molecules dissolved in a nematic liquid crystal. Magnitudes of dipole coupling constants have been determined for benzene and hexane, and their signs and assignments found from high order multiple quantum spectra. For the first time, a realistic impression of the conformation of hexane can be estimated from these results. Chapter 5 is a technical description of the MDB DCHIB-DR11W parallel interface which has been set up to transfer data between the Data General Nova 820 minicomputer, interfaced to the 360 MHz spectrometer, and the Vax 11/730. It covers operation of the boards, physical specifications and installation, and programs for testing and running the interface

  7. Rovibrational and temperature effects in theoretical studies of NMR parameters

    DEFF Research Database (Denmark)

    Faber, Rasmus; Kaminsky, Jakub; Sauer, Stephan P. A.

    2016-01-01

    The demand for high precision calculations of NMR shieldings (or their related values, chemical shifts δ) and spin-spin coupling constants facilitating and supporting detailed interpretations of NMR spectra increases hand in hand with the development of computational techniques and hardware...... resources. Highly sophisticated calculations including even relativistic effects are nowadays possible for these properties. However, NMR parameters depend not only on molecular structure and environment but also on molecular flexibility and temperature and the apparent success of theoretical predictions...

  8. Xenon NMR with spectroscopic, spatial, and temporal resolution

    OpenAIRE

    Münnemann, Kerstin

    2006-01-01

    129Xe NMR has found many applications in material sciences and medicine because of two useful properties of Xenon atoms for NMR: the sensitivity to their environment due to their highly polarizable electron cloud, which results in a wide range of chemical shifts, and the ability of being hyperpolarized, which overcomes the problem of the low signal-to-noise ratio of thermally polarized Xenon. In this work a variety of different experiments were performed that combine NMR measurements with spe...

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Misiewicz, Julia [Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry (Germany); Afonin, Sergii; Grage, Stephan L.; Berg, Jonas van den; Strandberg, Erik; Wadhwani, Parvesh [Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2) (Germany); Ulrich, Anne S., E-mail: anne.ulrich@kit.edu [Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry (Germany)

    2015-04-15

    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. {sup 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 {sup 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. {sup 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, {sup 2}H-NMR analysis of the acyl chain order parameter profiles showed that BP100 leads to considerable membrane thinning and thereby local destabilization.

  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.

  12. β-NMR of a thin Pt film

    Science.gov (United States)

    Fan, I.; Chow, K. H.; Parolin, T. J.; Egilmez, M.; Hossain, M. D.; Jung, J.; Keeler, T. A.; Kiefl, R. F.; Kreitzman, S. R.; Levy, C. D. P.; Ma, R.; Morris, G. D.; Pearson, M. R.; Saadaoui, H.; Salman, Z.; Smadella, M.; Song, Q.; Wang, D.; Xu, M.; MacFarlane, W. A.

    2009-04-01

    We report beta-detected NMR ( β-NMR) measurements on a 50 nm thick platinum (Pt) film grown on a magnesium oxide (MgO) substrate. The frequency of the β-NMR resonance in Pt was compared to the MgO reference frequency to estimate the Knight shift at various temperatures (100-300 K). The Knight shift was found to be negative and strongly temperature dependent. The implications are discussed and compared to other transition metals that have been studied via β-NMR previously.

  13. 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)

  14. beta-NMR of a thin Pt film

    Energy Technology Data Exchange (ETDEWEB)

    Fan, I., E-mail: ifan@phys.ualberta.c [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Chow, K.H. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Parolin, T.J. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Egilmez, M. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Hossain, M.D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Jung, J. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Keeler, T.A.; Kiefl, R.F. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Kreitzman, S.R.; Levy, C.D.P. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Ma, R. [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Morris, G.D.; Pearson, M.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Saadaoui, H. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Salman, Z. [Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom); ISIS Facility, Rutherford-Appleton Laboratory, Chilton, Didcot, Oxon, UK OX11 0QX (United Kingdom); Smadella, M.; Song, Q.; Wang, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Xu, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); MacFarlane, W.A. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

    2009-04-15

    We report beta-detected NMR (beta-NMR) measurements on a 50 nm thick platinum (Pt) film grown on a magnesium oxide (MgO) substrate. The frequency of the beta-NMR resonance in Pt was compared to the MgO reference frequency to estimate the Knight shift at various temperatures (100-300 K). The Knight shift was found to be negative and strongly temperature dependent. The implications are discussed and compared to other transition metals that have been studied via beta-NMR previously.

  15. A NMR spectrometer for educational purposes

    International Nuclear Information System (INIS)

    Colnago, Luiz A.; Torre Neto, Andre

    1991-01-01

    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. Structural study of pyrones by NMR

    International Nuclear Information System (INIS)

    Mandarino, D.G.

    1985-01-01

    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 C 13 -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.) [pt

  17. Dynamic NMR cardiac imaging in a piglet

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, M.; Rzedzian, R.; Mansfield, P. (Nottingham Univ. (UK). Dept. of Physics); Coupland, R.E. (Nottingham Univ. (UK). Queen' s Medical Centre)

    1983-12-01

    NMR echo-planar imaging (EPI) has been used in a real-time mode to visualise the thorax of a live piglet. Moving pictures are available on an immediate image display system which demonstrates dynamic cardiac function. Frame rates vary from one per cardiac cycle in a prospective stroboscopic mode with immediate visual output to a maximum of 10 frames per second yielding up to six looks in one piglet heart cycle, but using a visual playback mode. A completely new system has been used to obtain these images, features of which include a probe assembly with 22 cm access and an AP400 array processor for real-time data processing.

  18. 31 P-NMR, 77 Se-NMR and mass spectral studies on some ...

    African Journals Online (AJOL)

    A series of aminophosphines were prepared by controlled condensation reaction between PCl3 or PhPCl2 and amines, and they were converted into the corresponding chalcogenides. 31P-NMR and mass spectral data were collected for characterization of these asymmetrically substituted phosphines, and in addition, ...

  19. Crystallographic and dynamic aspects of solid-state NMR calibration compounds: towards ab initio NMR crystallography

    DEFF Research Database (Denmark)

    Li, Xiaozhou; Tapmeyer, Lukas; Bolte, Michael

    2016-01-01

    The excellent results of dispersion-corrected density functional theory (DFT-D) calculations for static systems have been well established over the past decade. The introduction of dynamics into DFT-D calculations is a target, especially for the field of molecular NMR crystallography. Four 13C ss...

  20. 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…

  1. 1H NMR spectra dataset and solid-state NMR data of cowpea (Vigna unguiculata)

    DEFF Research Database (Denmark)

    Alves Filho, Elenilson G.; Silva, Lorena M. A.; Teofilo, Elizita M.

    2017-01-01

    In this article the NMR data from chemical shifts, coupling constants, and structures of all the characterized compounds were provided, beyond a complementary PCA evaluation for the corresponding manuscript (E.G. Alves Filho, L.M.A. Silva, E.M. Teofilo, F.H. Larsen, E.S. de Brito, 2017) [3]. In a...

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

    NARCIS (Netherlands)

    Mierlo, van C.

    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

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

    Science.gov (United States)

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

    2015-01-01

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

  4. Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as 31P qNMR standards

    OpenAIRE

    Weber, Michael; Hellriegel, Christine; Rueck, Alexander; Wuethrich, Juerg; Jenks, Peter; Obkircher, Markus

    2014-01-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that 1H qNMR can be performed with high accuracy leading to measurement uncertainties below 1?% relative. It was even demonstrated that the combination of 1H qNMR with metrological weighing can lead to measurement uncertainties below 0....

  5. 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.

  6. Permeability in Rotliegend gas sandstones to gas and brine as predicted from NMR, mercury injection and image analysis

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Fabricius, Ida Lykke; Fisher, Quentin

    2015-01-01

    Permeability characterisation of low permeability, clay-rich gas sandstones is part of production forecasting and reservoir management. The physically based Kozeny (1927) equation linking permeability with porosity and pore size is derived for a porous medium with a homogeneous pore size, whereas...... the pore sizes in tight sandstones can range from nm to μm. Nuclear magnetic resonance (NMR) transverse relaxation was used to estimate a pore size distribution for 63 samples of Rotliegend sandstone. The surface relaxation parameter required to relate NMR to pore size is estimated by combination of NMR...... and mercury injection data. To estimate which pores control permeability to gas, gas permeability was calculated for each pore size increment by using the Kozeny equation. Permeability to brine is modelled by assuming a bound water layer on the mineral pore interface. The measured brine permeabilities...

  7. Analysis of trivalent cation complexation to functionalized mesoporous silica using solid-state NMR spectroscopy.

    Science.gov (United States)

    Shusterman, Jennifer; Mason, Harris; Bruchet, Anthony; Zavarin, Mavrik; Kersting, Annie B; Nitsche, Heino

    2014-11-28

    Functionalized mesoporous silica has applications in separations science, catalysis, and sensors. In this work, we studied the fundamental interactions of trivalent cations with functionalized mesoporous silica. We contacted trivalent cations of varying ionic radii with N-[5-(trimethoxysilyl)-2-aza-1-oxopentyl]caprolactam functionalized mesoporous silica with the aim of probing the binding mechanism of the metal to the surface of the solid. We studied the functionalized silica using solid-state nuclear magnetic resonance (NMR) spectroscopy before and after contact with the metals of interest. We collected NMR spectra of the various metals, as well as of (29)Si and (13)C to probe the silica substrate and the ligand properties, respectively. The NMR spectra indicate that the metals bind to the functionalized silica via two mechanisms. Aluminum sorbed to both the silica and the ligand, but with different coordination for each. Scandium also sorbed to both the silica and the ligand, and unlike the aluminum, had the same coordination number. Additionally, the functionalized silica was susceptible to acid hydrolysis and two primary mechanisms of degradation were observed: detachment from the silica surface and opening of the seven-membered ring in the ligand. Opening of the seven-membered ring may be beneficial in that it decreases steric hindrance of the molecule for binding.

  8. Quantification of radiation induced crosslinking in a commercial, toughened silicone rubber, TR-55, by 1H MQ-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Chinn, S; Alviso, C; Harvey, C A; Giuliani, J; Wilson, T; Cohenour, R

    2008-11-10

    Radiation induced degradation in a commercial, filled silicone composite has been studied by SPME/GC-MS, DMA, DSC, swelling, and Multiple Quantum NMR. Analysis of volatile and semivolatile species indicates degradation via decomposition of the peroxide curing catalyst and radiation induced backbiting reactions. DMA, swelling, and spin-echo NMR analysis indicate a increase in crosslink density of near 100% upon exposure to a cumulative dose of 250 kGray. Analysis of the sol-fraction via Charlseby-Pinner analysis indicates a ratio of chain scission to crosslinking yields of 0.38, consistent with the dominance of the crosslinking observed by DMA, swelling and spin-echo NMR and the chain scissioning reactions observed by MS analysis. Multiple Quantum NMR has revealed a bimodal distribution of residual dipolar couplings near 1 krad/sec and 5 krad/sec in an approximately 90:10 ratio, consistent with bulk network chains and chains associated with the filler surface. Upon exposure to radiation, the mean {Omega}{sub d} for both domains and the width of both domains both increased. The MQ NMR analysis provided increase insight into the effects of ionizing radiation on the network structure of silicone polymers.

  9. Vortex lattice disorder in YBa2Cu3O7-δ probed using β-NMR

    Science.gov (United States)

    Saadaoui, H.; Macfarlane, W. A.; Salman, Z.; Morris, G. D.; Song, Q.; Chow, K. H.; Hossain, M. D.; Levy, C. D. P.; Mansour, A. I.; Parolin, T. J.; Pearson, M. R.; Smadella, M.; Wang, D.; Kiefl, R. F.

    2009-12-01

    β -detected NMR (β-NMR) has been used to study vortex lattice disorder near the surface of the high- TC superconductor YBa2Cu3O7-δ (YBCO). The magnetic-field distribution from the vortex lattice was detected by implanting a low-energy beam of highly polarized L8i+ into a thin overlayer of silver on optimally doped, twinned, and detwinned YBCO samples. The resonance in Ag broadens significantly below the transition temperature TC as expected from the emerging field lines of the vortex lattice in YBCO. However, the lineshape is more symmetric and the dependence on the applied magnetic field is much weaker than expected from an ideal vortex lattice, indicating that the vortex density varies across the face of the sample, likely due to pinning at twin boundaries. At low temperatures the broadening from such disorder does not scale with the superfluid density.

  10. New class of aggregates in aqueous solution: an NMR, thermodynamic, and dynamic light scattering study.

    Science.gov (United States)

    Sanna, Cecilia; La Mesa, Camillo; Mannina, Luisa; Stano, Pasquale; Viel, Stéphane; Segre, Annalaura

    2006-07-04

    We investigated the aggregation properties of two classes of aromatic and hydrophobic compounds, namely chloroacetamides and ethyl 3-phenyl-2-nitropropionates, in moderately concentrated aqueous solution (millimolar range). The identification of all species present in solution under specific experimental conditions was performed by 1D and 2D NMR, pulsed gradient spin-echo NMR, and dynamic light scattering techniques. Some physical-chemical properties (viscosity, surface tension, and colligative properties) of the aqueous solutions were also determined. Both classes of compounds behave quite similarly: in solution, three distinct species, namely a monomeric species, small and mobile aggregates, and large and stiff aggregates, are observed. The results give insight into a new class of aggregates, held together by pi-pi interactions, which show an unusual associative behavior in water.

  11. NMR study of damage on isolated perfused rat heart exposed to ischemia and hypoxia

    International Nuclear Information System (INIS)

    Luo Xuechun; Yan Yongbin; Zhang Riqing; Fan Lili

    2001-01-01

    Myocardial ischemia is the most common and primary cause of myocardium damage. Numerous conventional techniques and methods have been developed for ischemia and reperfusion studies. However, because of damage to the heart sample, most of these techniques can not be used to continuously monitor the full dynamic course of the myocardial metabolic pathway. The nuclear magnetic resonance (NMR) surface coil technique, which overcomes the limitations of conventional instrumentation, can be used to quantitatively study every stage of the perfused heart (especially after perfusion stoppage) continuously, dynamically, and without damage under normal or designed physiological conditions at the molecular level. In this paper, 31 P-NMR was used to study the effects of ischemia and hypoxia on isolated perfused hearts. The results show that complete hypoxia caused more severe functional damage to the myocardial cells than complete ischemia

  12. Local environments and lithium adsorption on the iron oxyhydroxides lepidocrocite (gamma-FeOOH) and goethite (alpha-FeOOH): A 2H-2 and 7Li solid-state MAS NMR study

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Grey, Clare P.; Paik, Jonkim

    2008-01-01

    2H and 7LiMAS NMR spectroscopy techniques were applied to study the local surface and bulk environments of iron oxyhydroxide lepiclocrocite (gamma-FeOOH). 2H variable-temperature (VT) MAS NMR experiments were performed, showing the presence of short-range, strong antiferromagnetic correlations......, even at temperatures above the Neel temperature, TN, 77 K. The formation of a Li+ inner-sphere complex on the surface of lepiclocrocite was confirmed by the observation of a signal with a large 7Li hyperfine shift in the 7Li  MAS NMR spectrum. The effect of pH and relative humidity (RH...

  13. Characterization of interphases appearing on LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} using {sup 7}Li MAS NMR

    Energy Technology Data Exchange (ETDEWEB)

    Dupre, Nicolas; Guyomard, Dominique [Institut des Materiaux Jean Rouxel, 2 rue de la Houssiniere, BP 32229, F-44322 Nantes Cedex 3 (France); Martin, Jean-Frederic [Institut des Materiaux Jean Rouxel, 2 rue de la Houssiniere, BP 32229, F-44322 Nantes Cedex 3 (France); Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan); Yamada, Atsuo; Kanno, Ryoji [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8502 (Japan)

    2009-04-01

    {sup 7}Li MAS NMR, usually a bulk characterization technique, is used here to analyze the positive electrode/electrolyte interphase. The sharpening of the NMR spectra line shape as the amount of surface species increases shows that the observed signal is clearly the sum of signals due to the distribution of lithium ions in the interphase in terms of distance from the bulk of electrode active material. This technique is then used to compare characteristics of the interphase coming from the contact with LiPF{sub 6}-based electrolyte in the case of storage or electrochemical cycling. A clear influence of the change of potential on the interphase configuration and in particular on its intimacy with the bulk of active material is deduced from the change in NMR spectra lineshape. This information is hardly obtained by other characterization technique, making NMR a powerful tool for the study of interphases and passivation layers in lithium batteries materials. (author)

  14. "Perfecting" WATERGATE: clean proton NMR spectra from aqueous solution.

    Science.gov (United States)

    Adams, Ralph W; Holroyd, Chloe M; Aguilar, Juan A; Nilsson, Mathias; Morris, Gareth A

    2013-01-14

    A simple modification of the WATERGATE solvent suppression method greatly improves the quality of (1)H NMR spectra obtainable from samples in H(2)O. The new method allows (1)H signals to be measured even when close in chemical shift to the signal of water, as for example in the NMR spectra of carbohydrates.

  15. SPE-NMR metabolite sub-profiling of urine

    NARCIS (Netherlands)

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

    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

  16. EXPERIMENTAL AND THEORETICAL NMR STUDY OF 4-(1 ...

    African Journals Online (AJOL)

    Preferred Customer

    increased to cover various kinds of compounds, including biological, inorganic and organometallic compounds [8]. 1D and 2D hetero- and homonuclear NMR methods enable to get full assignments and structural information of organic compounds [9-11]. For the theoretical NMR investigations, the gauge including atomic ...

  17. Designing of high-resolution photoresists: use of modern NMR ...

    Indian Academy of Sciences (India)

    Applications of improved 1-D/ 2-D NMR spectroscopic techniques have been reviewed for quantitatively estimating the incorporation of different monomers and degree of linearity in resin microstructure. Comparison of the NMR data with those from lithography leads to a distinct correlation between resin microstructure and ...

  18. Rapid prediction of multi-dimensional NMR data sets

    International Nuclear Information System (INIS)

    Gradmann, Sabine; Ader, Christian; Heinrich, Ines; Nand, Deepak; Dittmann, Marc; Cukkemane, Abhishek; Dijk, Marc van; Bonvin, Alexandre M. J. J.; Engelhard, Martin; Baldus, Marc

    2012-01-01

    We present a computational environment for Fast Analysis of multidimensional NMR DAta Sets (FANDAS) that allows assembling multidimensional data sets from a variety of input parameters and facilitates comparing and modifying such “in silico” data sets during the various stages of the NMR data analysis. The input parameters can vary from (partial) NMR assignments directly obtained from experiments to values retrieved from in silico prediction programs. The resulting predicted data sets enable a rapid evaluation of sample labeling in light of spectral resolution and structural content, using standard NMR software such as Sparky. In addition, direct comparison to experimental data sets can be used to validate NMR assignments, distinguish different molecular components, refine structural models or other parameters derived from NMR data. The method is demonstrated in the context of solid-state NMR data obtained for the cyclic nucleotide binding domain of a bacterial cyclic nucleotide-gated channel and on membrane-embedded sensory rhodopsin II. FANDAS is freely available as web portal under WeNMR (http://www.wenmr.eu/services/FANDAShttp://www.wenmr.eu/services/FANDAS).

  19. Recent excitements in protein NMR: Large proteins and biologically ...

    Indian Academy of Sciences (India)

    2016-10-14

    Oct 14, 2016 ... quality. These problems severely limit NMR studies of large molecules, which is directly reflected in a fewer number of. NMR-derived protein structures with ...... Energy landscape of CAP* showing the two states, inactive (I) and active (A), and their fractional populations (93% and 7%, respectively).

  20. Probe for high resolution NMR with sample reorientation

    Science.gov (United States)

    Pines, A.; Samoson, A.

    1990-02-06

    An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions are zero. 8 figs.

  1. Bringing NMR and IR Spectroscopy to High Schools

    Science.gov (United States)

    Bonjour, Jessica L.; Hass, Alisa L.; Pollock, David W.; Huebner, Aaron; Frost, John A.

    2017-01-01

    Development of benchtop, portable Fourier transform nuclear magnetic resonance (NMR) and infrared (IR) spectrometers has opened up opportunities for creating university-high school partnerships that provide high school students with hands-on experience with NMR and IR instruments. With recent changes to the international baccalaureate chemistry…

  2. Improved Baseline in 29Si NMR Spectra of Water Glasses

    Czech Academy of Sciences Publication Activity Database

    Schraml, Jan; Sandor, P.; Korec, S.; Krump, M.; Foller, B.

    2013-01-01

    Roč. 51, č. 7 (2013), s. 403-406 ISSN 0749-1581 Grant - others:GA MPO(CZ) FR-TI1/335; GA MŠk(CZ) LM2011020 Institutional support: RVO:67985858 Keywords : NMR * 29Si NMR * acoustic ringing Subject RIV: JI - Composite Materials Impact factor: 1.559, year: 2013

  3. NMR Probe for Electrons in Semiconductor Mesoscopic Structures

    Indian Academy of Sciences (India)

    2009-11-14

    Nov 14, 2009 ... NMR Probe for Electrons in. Semiconductor. Mesoscopic Structures. Vikram Tripathi. TIFR, Mumbai. IInd Platinum Jubilee Meeting. Indian Academy of Sciences. Bangalore ... We showed NMR techniques can be very useful in such circumstances. .... Exploit the main physical difference. Low energy (long ...

  4. 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.

  5. Fast mapping of global protein folding states by multivariate NMR:

    DEFF Research Database (Denmark)

    Malmendal, Anders; Underhaug, Jarl; Otzen, Daniel

    2010-01-01

    that provides such an overview. GPS NMR exploits the unique ability of NMR to simultaneously record signals from individual hydrogen atoms in complex macromolecular systems and of multivariate analysis to describe spectral variations from these by a few variables for establishment of, and positioning in......, protein-folding state maps. The method is fast, sensitive, and robust, and it works without isotope-labelling. The unique capabilities of GPS NMR to identify different folding states and to compare different unfolding processes are demonstrated by mapping of the equilibrium folding space of bovine alpha......To obtain insight into the functions of proteins and their specific roles, it is important to establish efficient procedures for exploring the states that encapsulate their conformational space. Global Protein folding State mapping by multivariate NMR (GPS NMR) is a powerful high-throughput method...

  6. Optimized fast mixing device for real-time NMR applications

    Science.gov (United States)

    Franco, Rémi; Favier, Adrien; Schanda, Paul; Brutscher, Bernhard

    2017-08-01

    We present an improved fast mixing device based on the rapid mixing of two solutions inside the NMR probe, as originally proposed by Hore and coworkers (J. Am. Chem. Soc. 125 (2003) 12484-12492). Such a device is important for off-equilibrium studies of molecular kinetics by multidimensional real-time NMR spectrsocopy. The novelty of this device is that it allows removing the injector from the NMR detection volume after mixing, and thus provides good magnetic field homogeneity independently of the initial sample volume placed in the NMR probe. The apparatus is simple to build, inexpensive, and can be used without any hardware modification on any type of liquid-state NMR spectrometer. We demonstrate the performance of our fast mixing device in terms of improved magnetic field homogeneity, and show an application to the study of protein folding and the structural characterization of transiently populated folding intermediates.

  7. NMR and the surgery of tumours at the craniocervical junction

    International Nuclear Information System (INIS)

    Ahyai, A.; Matsumara, A.; Rittmeyer, K.

    1987-01-01

    The diagnosis of tumors in the posterior fossa and at the craniocervical junction has always been problematic. In this region of the brain a clear visualization of the exact extent and relations of a space-occupying lesion is indispensable in assessing whether it is operable. Even though a tumor with its perifocal edema can be detected by CT, NMR opens new perspectives for the neurosurgeon. The authors present these cases in 3 groups. Group 1 comprises patients for whom NMR results contra-indicated operation. Group II consists of patients who would probably not have been operated on prior to the use of NMR. Group III includes patients who would probably not have been operated on prior to the use of NMR (e.g arachnoid cysts, Dandy-Walker malformations, etc); the excellent multi-dimensional imaging by NMR rendered the advisability of operation questionable, so that improved diagnostics may have spared the patients unnecessary operations

  8. $\\beta$-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.

  9. High-Sensitivity Rheo-NMR Spectroscopy for Protein Studies.

    Science.gov (United States)

    Morimoto, Daichi; Walinda, Erik; Iwakawa, Naoto; Nishizawa, Mayu; Kawata, Yasushi; Yamamoto, Akihiko; Shirakawa, Masahiro; Scheler, Ulrich; Sugase, Kenji

    2017-07-18

    Shear stress can induce structural deformation of proteins, which might result in aggregate formation. Rheo-NMR spectroscopy has the potential to monitor structural changes in proteins under shear stress at the atomic level; however, existing Rheo-NMR methodologies have insufficient sensitivity to probe protein structure and dynamics. Here we present a simple and versatile approach to Rheo-NMR, which maximizes sensitivity by using a spectrometer equipped with a cryogenic probe. As a result, the sensitivity of the instrument ranks highest among the Rheo-NMR spectrometers reported so far. We demonstrate that the newly developed Rheo-NMR instrument can acquire high-quality relaxation data for a protein under shear stress and can trace structural changes in a protein during fibril formation in real time. The described approach will facilitate rheological studies on protein structural deformation, thereby aiding a physical understanding of shear-induced amyloid fibril formation.

  10. Crystallographically-based analysis of the NMR spectra of maghemite

    International Nuclear Information System (INIS)

    Spiers, K.M.; Cashion, J.D.

    2012-01-01

    All possible iron environments with respect to nearest neighbour vacancies in vacancy-ordered and vacancy-disordered maghemite have been evaluated and used as the foundation for a crystallographically-based analysis of the published NMR spectra of maghemite. The spectral components have been assigned to particular configurations and excellent agreement obtained in comparing predicted spectra with published spectra taken in applied magnetic fields. The broadness of the published NMR lines has been explained by calculations of the magnetic dipole fields at the various iron sites and consideration of the supertransferred hyperfine fields. - Highlights: ► Analysis of 57 Fe NMR of maghemite based on vacancy ordering and nearest neighbour vacancies. ► Assignment of NMR spectral components based on crystallographic analysis of unique iron sites. ► Strong agreement between predicted spectra and published spectra taken in applied magnetic fields. ► Maghemite NMR spectral broadening due to various iron sites and supertransferred hyperfine field.

  11. Investigation of zeolites by solid state quadrapole NMR

    International Nuclear Information System (INIS)

    Janssen, R.

    1990-01-01

    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 23 Na-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

  12. NMR spectroscopy: a tool for conformational analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tormena, Claudio F.; Cormanich, Rodrigo A.; Rittner, Roberto, E-mail: rittner@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica. Lab. de Fisico-Quimica Organica; Freitas, Matheus P. [Universidade Federal de Lavras (UFLA), MG (Brazil). Dept. de Qumica

    2011-07-01

    The present review deals with the application of NMR data to the conformational analysis of simple organic compounds, together with other experimental methods like infrared spectroscopy and with theoretical calculations. Each sub-section describes the results for a group of compounds which belong to a given organic function like ketones, esters, etc. Studies of a single compound, even of special relevance, were excluded since the main goal of this review is to compare the results for a given function, where different substituents were used or small structural changes were introduced in the substrate, in an attempt to disclose their effects in the conformational equilibrium. Moreover, the huge amount of data available in the literature, on this research field, imposed some limitations which will be detailed in the Introduction, but it can be reminded in advance that these limitations include mostly the period when these results were published. (author)

  13. NMR spectroscopy: a tool for conformational analysis

    International Nuclear Information System (INIS)

    Tormena, Claudio F.; Cormanich, Rodrigo A.; Rittner, Roberto; Freitas, Matheus P.

    2011-01-01

    The present review deals with the application of NMR data to the conformational analysis of simple organic compounds, together with other experimental methods like infrared spectroscopy and with theoretical calculations. Each sub-section describes the results for a group of compounds which belong to a given organic function like ketones, esters, etc. Studies of a single compound, even of special relevance, were excluded since the main goal of this review is to compare the results for a given function, where different substituents were used or small structural changes were introduced in the substrate, in an attempt to disclose their effects in the conformational equilibrium. Moreover, the huge amount of data available in the literature, on this research field, imposed some limitations which will be detailed in the Introduction, but it can be reminded in advance that these limitations include mostly the period when these results were published. (author)

  14. Dynamic NMR cardiac imaging in a piglet

    International Nuclear Information System (INIS)

    Doyle, M.; Rzedzian, R.; Mansfield, P.; Coupland, R.E.

    1983-01-01

    NMR echo-planar imaging (EPI) has been used in a real-time mode to visualise the thorax of a live piglet. Moving pictures are available on an immediate image display system which demonstrates dynamic cardiac function. Frame rates vary from one per cardiac cycle in a prospective stroboscopic mode with immediate visual output to a maximum of 10 frames per second yielding up to six looks in one piglet heart cycle, but using a visual playback mode. A completely new system has been used to obtain these images, features of which include a probe assembly with 22 cm access and an AP400 array processor for real-time data processing. (author)

  15. ImatraNMR: Novel software for batch integration and analysis of quantitative NMR spectra

    Science.gov (United States)

    Mäkelä, A. V.; Heikkilä, O.; Kilpeläinen, I.; Heikkinen, S.

    2011-08-01

    Quantitative NMR spectroscopy is a useful and important tool for analysis of various mixtures. Recently, in addition of traditional quantitative 1D 1H and 13C NMR methods, a variety of pulse sequences aimed for quantitative or semiquantitative analysis have been developed. To obtain actual usable results from quantitative spectra, they must be processed and analyzed with suitable software. Currently, there are many processing packages available from spectrometer manufacturers and third party developers, and most of them are capable of analyzing and integration of quantitative spectra. However, they are mainly aimed for processing single or few spectra, and are slow and difficult to use when large numbers of spectra and signals are being analyzed, even when using pre-saved integration areas or custom scripting features. In this article, we present a novel software, ImatraNMR, designed for batch analysis of quantitative spectra. In addition to capability of analyzing large number of spectra, it provides results in text and CSV formats, allowing further data-analysis using spreadsheet programs or general analysis programs, such as Matlab. The software is written with Java, and thus it should run in any platform capable of providing Java Runtime Environment version 1.6 or newer, however, currently it has only been tested with Windows and Linux (Ubuntu 10.04). The software is free for non-commercial use, and is provided with source code upon request.

  16. Can NMR solve some significant challenges in metabolomics?

    Science.gov (United States)

    Nagana Gowda, G. A.; Raftery, Daniel

    2015-11-01

    The field of metabolomics continues to witness rapid growth driven by fundamental studies, methods development, and applications in a number of disciplines that include biomedical science, plant and nutrition sciences, drug development, energy and environmental sciences, toxicology, etc. NMR spectroscopy is one of the two most widely used analytical platforms in the metabolomics field, along with mass spectrometry (MS). NMR's excellent reproducibility and quantitative accuracy, its ability to identify structures of unknown metabolites, its capacity to generate metabolite profiles using intact bio-specimens with no need for separation, and its capabilities for tracing metabolic pathways using isotope labeled substrates offer unique strengths for metabolomics applications. However, NMR's limited sensitivity and resolution continue to pose a major challenge and have restricted both the number and the quantitative accuracy of metabolites analyzed by NMR. Further, the analysis of highly complex biological samples has increased the demand for new methods with improved detection, better unknown identification, and more accurate quantitation of larger numbers of metabolites. Recent efforts have contributed significant improvements in these areas, and have thereby enhanced the pool of routinely quantifiable metabolites. Additionally, efforts focused on combining NMR and MS promise opportunities to exploit the combined strength of the two analytical platforms for direct comparison of the metabolite data, unknown identification and reliable biomarker discovery that continue to challenge the metabolomics field. This article presents our perspectives on the emerging trends in NMR-based metabolomics and NMR's continuing role in the field with an emphasis on recent and ongoing research from our laboratory.

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

    Science.gov (United States)

    Cobas, Carlos; Iglesias, Isaac; Seoane, Felipe

    2015-08-01

    Touch-screen computers are emerging as a popular platform for many applications, including those in chemistry and analytical sciences. In this work, we present our implementation of a new NMR 'app' designed for hand-held and portable touch-controlled devices, such as smartphones and tablets. It features a flexible architecture formed by a powerful NMR processing and analysis kernel and an intuitive user interface that makes full use of the smart devices haptic capabilities. Routine 1D and 2D NMR spectra acquired in most NMR instruments can be processed in a fully unattended way. More advanced experiments such as non-uniform sampled NMR spectra are also supported through a very efficient parallelized Modified Iterative Soft Thresholding algorithm. Specific technical development features as well as the overall feasibility of using NMR software apps will also be discussed. All aspects considered the functionalities of the app allowing it to work as a stand-alone tool or as a 'companion' to more advanced desktop applications such as Mnova NMR. Copyright © 2015 John Wiley & Sons, Ltd.

  18. NMR study of local diamagnetic properties of carbon structures with multiwalled nanotubes

    International Nuclear Information System (INIS)

    Nikolaev, E.G.; Omel'yanovsky, O.E.; Prudkovsky, V.S.; Sadakov, A.V.; Tsebro, V.I.

    2009-01-01

    The reasons for the high diamagnetic susceptibility of carbon columns, which are covered with a nanotube mesh, from the interior part of cathode deposits have been studied by means of NMR. A comparative study is made of the 13 C NMR spectra and the magnetic susceptibility of carbon columns before and after ultrasonic processing as well as of finely dispersed material, obtained as a result of such processing, enriched with multilayer nanotubes. The strong diamagnetism of the carbon columns is apparently associated with a quite dense conglomerate of graphite particles, nanotubes, and multilayer polyhedral particles present in their core and not with the surface mesh of multilayer nanotubes. To make a more accurate determination of the character of the anisotropy of the magnetic susceptibility of multilayer carbon nanotubes, the form of the 13 C NMR spectra of samples enriched with multilayer nanotubes, where the nanotubes are either not oriented or only partially oriented, is analyzed. It is shown that the diamagnetic susceptibility of multilayer carbon nanotubes is highest when the magnetic field is oriented perpendicular to their axis

  19. Structure and orientation of dynorphin bound to lipid bilayers by 13C solid-state NMR

    Science.gov (United States)

    Uezono, Takiko; Toraya, Shuichi; Obata, Maki; Nishimura, Katsuyuki; Tuzi, Satoru; Saitô, Hazime; Naito, Akira

    2005-07-01

    Secondary structure and orientation of dynorphin bound to dimyristoylphosphatidylcholine (DMPC) bilayer were investigated by solid-state 13C NMR spectroscopy. For this purpose, 13C NMR spectra of the site-specifically 13C-labeled dynorphin were measured in the membrane-bound state under static, magic angle spinning (MAS), and slow MAS conditions. In the static experiment, magnetically oriented vesicle system (MOVS) induced by dynorphin was successfully used to investigate the orientation of dynorphin bound to the lipid bilayers. It was found that dynorphin adopts an α-helical structure in the N-terminus from Gly 2 to Leu 5 by analyses of the isotropic chemical shifts obtained from the MAS experiments. In contrast, it adopts disordered conformations from the center to the C-terminus and is located on the membrane surface. The static 13C NMR spectra indicated that MOVS-bound dynorphin was oriented to the magnetic field and rotated rapidly about the bilayer normal. Subsequently, we analyzed the 13C chemical shift tensors of carbonyl carbons in the peptide backbone by considering the rotational motion of the N-terminal α-helix. It was revealed that the N-terminal α-helix is inserted into the membrane with the tilt angle of 21° to the bilayer normal. This structure suggests a possibility that dynorphin interacts with the extracellular loop II of the κ-receptor through a helix-helix interaction.

  20. Solid-state (49/47)Ti NMR of titanium-based MCM-41 hybrid materials.

    Science.gov (United States)

    Ballesteros, Ruth; Fajardo, Mariano; Sierra, Isabel; Force, Carmen; del Hierro, Isabel

    2009-11-03

    Titanium solid-state NMR spectroscopy data for a series of organic-inorganic titanium MCM-41 based materials have been collected. These materials have been synthesized by first modifying the mesoporous silica MCM-41 in one step with a mixture of silanes: a triazine propyl triethoxysilane acting as functional linker and methyltrimethoxysilane or hexamethyldisilizane as capped agents to mask the remaining silanol groups. Second, the appropiate titanium precursor Ti(OPr(i))(4), [{Ti(OPr(i))(3)(OMent)}(2)] (OMent = 1R,2S,5R-(-)-menthoxo), Ti(OPr(i))(4), or [Ti(eta(5)-C(5)HMe(4))Cl(3)], has been immobilized by reaction with the modified MCM-41. Finally, after Ti(OPr(i))(4) immobilization onto the organomodified support the reaction with the chiral (+)-diethyl-l-tartrate was accomplished. The materials without functional linker have been also prepared by reaction in one step of the capped agent and the titanium precursor with the mesoporous silica. Relevant correlations of titanium NMR resonance chemical shifts and line widths can be inferred depending on different factors. The immobilization procedure used to prepare titanium-based MCM-41 hybrid materials and the choice of the silylating reagents employed to mask the silanol groups present on the silica surfaces produce significant differences in the Ti NMR spectra. Furthermore, depending on the electronic and sterical influence of the substituents directly attached to the titanium center, chemical shifts and line widths are modified providing novel information about titanium structure.

  1. Application of NMR Methods to Identify Detection Reagents for Use in the Development of Robust Nanosensors

    Energy Technology Data Exchange (ETDEWEB)

    Cosman, M; Krishnan, V V; Balhorn, R

    2004-04-29

    Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique for studying bi-molecular interactions at the atomic scale. Our NMR lab is involved in the identification of small molecules, or ligands that bind to target protein receptors, such as tetanus (TeNT) and botulinum (BoNT) neurotoxins, anthrax proteins and HLA-DR10 receptors on non-Hodgkin's lymphoma cancer cells. Once low affinity binders are identified, they can be linked together to produce multidentate synthetic high affinity ligands (SHALs) that have very high specificity for their target protein receptors. An important nanotechnology application for SHALs is their use in the development of robust chemical sensors or biochips for the detection of pathogen proteins in environmental samples or body fluids. Here, we describe a recently developed NMR competition assay based on transferred nuclear Overhauser effect spectroscopy (trNOESY) that enables the identification of sets of ligands that bind to the same site, or a different site, on the surface of TeNT fragment C (TetC) than a known ''marker'' ligand, doxorubicin. Using this assay, we can identify the optimal pairs of ligands to be linked together for creating detection reagents, as well as estimate the relative binding constants for ligands competing for the same site.

  2. New insight into the microtexture of chalks from NMR analysis

    DEFF Research Database (Denmark)

    Faÿ-Gomord, Ophélie; Soete, Jeroen; Katika, Konstantina

    2016-01-01

    An integrated petrographical and petrophysical study was carried out on a set of 35 outcrop chalk samples, covering a wide range of lithologies and textures. In this study various chalk rock-types have been characterized, in terms of microtextures and porous network, by integrating both geological...... quality chalks independently of their sedimentological and/or diagenetic history. The study aims to develop an NMR-based approach to characterize a broad range of chalk samples. The provided laboratory low-field NMR chalk classification can be used as a guide to interpret NMR logging data...

  3. High-field NMR using resistive and hybrid magnets

    Science.gov (United States)

    Gan, Zhehong; Kwak, Hyung-Tae; Bird, Mark; Cross, Timothy; Gor'kov, Peter; Brey, William; Shetty, Kiran

    2008-03-01

    Resistive and resistive-superconducting hybrid magnets can generate dc magnetic fields much higher than conventional superconducting NMR magnets but the field spatial homogeneity and temporal stability are usually not sufficient for high-resolution NMR experiments. Hardware and technique development addressing these issues are presented for high-resolution NMR at magnetic fields up to 40 T. Passive ferromagnetic shimming and magic-angle spinning are used effectively to reduce the broadening from inhomogeneous magnetic field. A phase correction technique based on simultaneous heteronuclear detection is developed to compensate magnetic field fluctuations to achieve high spectral resolution.

  4. NMR imaging of bladder tumors in males. Preliminary clinical experience

    International Nuclear Information System (INIS)

    Sigal, R.; Rein, A.J.J.T.; Atlan, H.; Lanir, A.; Kedar, S.; Segal, S.

    1985-01-01

    Nuclear magnetic resonance (NMR) of the normal and pathologic bladder was performed in 10 male subjects: 5 normal volunteers, 4 with bladder primary carcinoma, 1 with bladder metastasis. All scanning was done using a superconductive magnet operating at 0.5 T. Spin echo was used as pulse sequence. The diagnosis was confirmed in all cases by NMR imaging. The ability of the technique to provide images in axial, sagital and coronal planes allowed a precise assessment of the morphology and the size of the tumors. The lack of hazards and the quality of images may promote NMR imaging to a prominent role in the diagnosis of human bladder cancer [fr

  5. NMR studies of metallic tin confined within porous matrices

    International Nuclear Information System (INIS)

    Charnaya, E. V.; Tien, Cheng; Lee, M. K.; Kumzerov, Yu. A.

    2007-01-01

    119 Sn NMR studies were carried out for metallic tin confined within synthetic opal and porous glass. Tin was embedded into nanoporous matrices in the melted state under pressure. The Knight shift for liquid confined tin was found to decrease with decreasing pore size. Correlations between NMR line shapes, Knight shift, and pore filling were observed. The melting and freezing phase transitions of tin under confinement were studied through temperature dependences of NMR signals upon warming and cooling. Melting of tin within the opal matrix agreed well with the liquid skin model suggested for small isolated particles. The influence of the pore filling on the melting process was shown

  6. Recent developments in combining LODESR imaging with proton NMR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, I.; Robb, F.J.L.; McCallum, S.J.; Koptioug, A.; Lurie, D.J. [Department of Biomedical Physics and Bioengineering, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD (United Kingdom)

    1998-07-01

    We have designed and constructed RF coil assemblies and the appropriate instrumentation for combining proton NMR imaging with LODESR imaging. This has enabled us to collect sequential images from the same sample using both methods. The coil assembly consists of a crossed ellipse coil for LODESR and proton NMR signal detection and a saddle coil for excitation of the ESR resonance. Images have been collected of phantoms containing copper sulphate and Tempol solutions. NMR images were collected (4.3 min) and within 30 s LODESR data collection started (collection time 2.5 min). Only the Tempol solutions are visible in the LODESR images. (author)

  7. Characterisation of triacetone triperoxide (TATP) conformers using LC-NMR.

    Science.gov (United States)

    Haroune, Nicolas; Crowson, Andrew; Campbell, Bill

    2011-06-01

    Previous studies [1,2] have reported the existence of two conformers of TATP. This study demonstrates the ability of LC-NMR to separate and characterise the individual conformers. The NMR data is consistent with the proposed structures for the two conformers. Re-equilibration can be followed by NMR and the kinetics of the process studied. Over the past decade the use of the explosive TATP in terrorist devices has increased. Therefore, the ability to analyse and characterise this material has assumed greater importance. Copyright © 2010 Forensic Science Society. All rights reserved.

  8. NMR and domain wall mobility in intermetallic compounds

    International Nuclear Information System (INIS)

    Guimaraes, A.P.; Sampaio, L.C.; Cunha, S.F.; Alves, K.M.B.

    1991-01-01

    The technique of pulsed NMR can be used to study the distribution of hyperfine fields in a magnetic matrix. The dynamics of the domain walls are relevant to the generation of NMR signals. In the present study on the (R x Y 1-x ) Fe 2 intermetallic compounds, the reduction in the signals is associated to increased propagation fields. This indicates that a smaller domain wall mobility is at the origin of these effects. NMR spectra in this system show the importance of direct and indirect (i.e., mediated by Fe atoms) terms in the transferred hyperfine field. (author)

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

    DEFF Research Database (Denmark)

    Savorani, Francesco; Rasmussen, Morten Arendt; Mikkelsen, Mette Skau

    2013-01-01

    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......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...

  10. Joint inversion of NMR and SIP data to estimate pore size distribution of geomaterials

    Science.gov (United States)

    Niu, Qifei; Zhang, Chi

    2018-03-01

    There are growing interests in using geophysical tools to characterize the microstructure of geomaterials because of the non-invasive nature and the applicability in field. In these applications, multiple types of geophysical data sets are usually processed separately, which may be inadequate to constrain the key feature of target variables. Therefore, simultaneous processing of multiple data sets could potentially improve the resolution. In this study, we propose a method to estimate pore size distribution by joint inversion of nuclear magnetic resonance (NMR) T2 relaxation and spectral induced polarization (SIP) spectra. The petrophysical relation between NMR T2 relaxation time and SIP relaxation time is incorporated in a nonlinear least squares problem formulation, which is solved using Gauss-Newton method. The joint inversion scheme is applied to a synthetic sample and a Berea sandstone sample. The jointly estimated pore size distributions are very close to the true model and results from other experimental method. Even when the knowledge of the petrophysical models of the sample is incomplete, the joint inversion can still capture the main features of the pore size distribution of the samples, including the general shape and relative peak positions of the distribution curves. It is also found from the numerical example that the surface relaxivity of the sample could be extracted with the joint inversion of NMR and SIP data if the diffusion coefficient of the ions in the electrical double layer is known. Comparing to individual inversions, the joint inversion could improve the resolution of the estimated pore size distribution because of the addition of extra data sets. The proposed approach might constitute a first step towards a comprehensive joint inversion that can extract the full pore geometry information of a geomaterial from NMR and SIP data.

  11. Value of NMR Parameters and DFT Calculations for Quantum Information Processing Utilizing Phosphorus Heterocycles.

    Science.gov (United States)

    Lino, Jéssica B R; Rocha, Eduardo P; Ramalho, Teodorico C

    2017-06-15

    Quantum computing is the field of science that uses quantum-mechanical phenomena, such as superposition and entanglement, to perform operations on data. The fundamental information unit used in quantum computing is the quantum bit or qubit. It is well-known that quantum computers could theoretically be able to solve problems much more quickly than any classical computers. Currently, the first and still the most successful implementations of quantum information processing (QIP) have been based on nuclear spins in liquids. However, molecules that enable many qubits NMR QIP implementations should meet some conditions: have large chemical shifts and be appropriately dispersed for qubit addressability, appreciable spin-spin coupling between any pair of spins, and a long relaxation time. In this line, benzyldene-2,3-dihydro-1H-[1,3]diphosphole (BDF) derivatives have been theoretically tested for maximizing large chemical shifts, spin-spin coupling, and minimizing the hyperfine coupling constant. Thus, the structures were optimized at the B3LYP/6-311G(d,p) level and showed a significant similarity with the experimental geometrical parameters. The NMR spectroscopic parameters (δ and J) were calculated with six different DFT functionals. The τ-HCTH/6-31G(2d) level is in better agreement with the experimental data of 31 P and 13 C chemical shifts, while PCM-B3LYP/cc-pVDZ level shows a decrease on deviation between calculated and experimental values for P-P and P-C SSCC. The surface response technique was employed to rationalize how the hyperfine constant varies with the chemical shifts and coupling constants values. From our findings, BDF-NO 2 was the best candidate for NMR quantum computations (NMR-QC) among the studied series.

  12. [Optimization of experimental parameters for quantitative NMR (qNMR) and its application in quantitative analysis of traditional Chinese medicines].

    Science.gov (United States)

    Ma, Xiao-Li; Zou, Ping-Ping; Lei, Wei; Tu, Peng-Fei; Jiang, Yong

    2014-09-01

    Quantitative NMR (qNMR) is a technology based on the principle of NMR. This technology does not need the references of the determined components, which supplies a solution for the problem of reference scarcity in the quantitative analysis of traditional Chinese medicines. Moreover, this technology has the advantages of easy operation, non-destructiveness for the determined sample, high accuracy and repeatability, in comparison with HPLC, LC-MS and GC-MS. NMR technology has achieved quantum leap in sensitivity and accuracy with the development of NMR hardware. In addition, the choice of appropriate experimental parameters of the pre-treatment and measurement procedure as well as the post-acquisition processing is also important for obtaining high-quality and reproducible NMR spectra. This review summarizes the principle of qHNMR, the various experimental parameters affecting the accuracy and the precision of qHNMR, such as signal to noise ratio, relaxation delay, pulse width, acquisition time, window function, phase correction and baseline correction, and their corresponding optimized methods. Moreover, the application of qHNMR in the fields of quantitation of single or multi-components of traditional Chinese medicines, the purity detection of references, and the quality analysis of foods has been discussed. In addition, the existing questions and the future application prospects of qNMR in natural product areas are also presented.

  13. Study on the Effects of Oligo chitosan and Bioliquifert on Two Rice Mutants, NMR 151 and NMR 152

    International Nuclear Information System (INIS)

    Shakinah Salleh; Faiz Ahmad; Sobri Hussein

    2016-01-01

    Nuclear Malaysia has successfully developed two new rice mutants namely NMR 151 and NMR 152. In addition, Nuclear Malaysia has also successfully developed Oligo chitosan and liquid bio fertilizer (Bioliquifert). Oligo chitosan acts as elicitor that has been proven to be very effective in controlling disease infections and improving yield productivity. Bioliquifert on the other hand is a mixture of microbes containing major nutrient-providing microorganisms. The objective of this study is to observe the effects of Oligo chitosan and Bioliquifert on rice mutants, NMR 151 and NMR 152. The treatment was applied on 14 day old seedlings of MR 219, NMR 151 and NMR 152 sowed in 20 cm pots containing silty clay from the paddy soil of Tanjung Karang, Selangor. The seedlings were then placed in the greenhouse at Nuclear Malaysia until it reaches 110 days old. Study was conducted in a Complete Randomized Design (CRD) with 3 replications was used and each replication consisted of three plants. All treatments received compound and single dressing fertilizer as recommended by National Rice Production Package except for Treatment 2 and 3, in which Treatment 2 received Oligo chitosan and Bioliquifert while Treatment 3 only received Bioliquifert. Results on plant height, number of tiller and plant fresh weight are not significantly different for all cultivar except for seed dry weight of NMR 152 and MR 219. (author)

  14. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    Energy Technology Data Exchange (ETDEWEB)

    Dempsey, C.; Bitbol, M.; Watts, A. (Oxford Univ. (England))

    1989-08-08

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the {alpha}- and {beta}-methylenes of the choline head group (DMPC-d{sub 4}) and dimyristoylphosphatidylserine deuterated in the {alpha}-methylene and {beta}-CH positions of the serine head group (DMPS-d{sub 3}) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d{sub 4} induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d{sub 4} in the ternary mixture was similar to the spectrum from pure DMPC-d{sub 4} bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d{sub 3} indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d{sub 4} results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide.

  15. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    International Nuclear Information System (INIS)

    Dempsey, C.; Bitbol, M.; Watts, A.

    1989-01-01

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the α- and β-methylenes of the choline head group (DMPC-d 4 ) and dimyristoylphosphatidylserine deuterated in the α-methylene and β-CH positions of the serine head group (DMPS-d 3 ) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d 4 induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d 4 in the ternary mixture was similar to the spectrum from pure DMPC-d 4 bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d 3 indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d 4 results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide

  16. Vortex lattice disorder in YBa2Cu3O studied with β-NMR

    Science.gov (United States)

    Saadaoui, H.; MacFarlane, W. A.; Morris, G. D.; Salman, Z.; Chow, K. H.; Fan, I.; Hossain, M. D.; Liang, R.; Mansour, A. I.; Parolin, T. J.; Smadella, M.; Song, Q.; Wang, D.; Kiefl, R. F.

    2009-04-01

    In this paper, we report Li+8β-NMR measurements in thin Ag films deposited on the surface of YBa2Cu3O (YBCO) in the vortex state. The resonance in the Ag overlayer broadens dramatically below the superconducting transition temperature Tc, as expected from the underlying vortex lattice in the YBCO. However, the lineshape is much broader and more symmetric than expected for an ideal vortex lattice. These results indicate the observed field distribution in the Ag overlayer is dominated by extrinsic, long length scale disorder.

  17. Artificial intelligence in NMR imaging and image processing

    International Nuclear Information System (INIS)

    Kuhn, M.H.

    1988-01-01

    NMR tomography offers a wealth of information and data acquisition variants. Artificial intelligence is able to efficiently support the selection of measuring parameters and the evaluation of results. (orig.) [de

  18. NMR with Combined Antiangiogenic and Radiation Therapies - Breast Cancer

    National Research Council Canada - National Science Library

    Brown, Stephen

    2000-01-01

    The original goal of the present study was to determine optimal strategies for combining radiation and antiangiogenic therapies in spontaneous murine tumors and to evaluate the potential of Nuclear Magnetic Resonance (NMR...

  19. Studies on supramolecular gel formation using DOSY NMR

    Czech Academy of Sciences Publication Activity Database

    Nonappa, N.; Šaman, David; Kolehmainen, E.

    2015-01-01

    Roč. 53, č. 4 (2015), s. 256-260 ISSN 0749-1581 Institutional support: RVO:61388963 Keywords : DOSY * VT NMR * gel * diffusion coefficients Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.226, year: 2015

  20. Cell signaling, post-translational protein modifications and NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Theillet, Francois-Xavier [In-cell NMR Group, Department of NMR-Supported Structural Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin) (Germany); Smet-Nocca, Caroline [Universite Lille Nord de France, CNRS UMR 8576 (France); Liokatis, Stamatios; Thongwichian, Rossukon; Kosten, Jonas [In-cell NMR Group, Department of NMR-Supported Structural Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin) (Germany); Yoon, Mi-Kyung; Kriwacki, Richard W. [St. Jude Children' s Research Hospital, Department of Structural Biology (United States); Landrieu, Isabelle; Lippens, Guy [Universite Lille Nord de France, CNRS UMR 8576 (France); Selenko, Philipp, E-mail: selenko@fmp-berlin.de [In-cell NMR Group, Department of NMR-Supported Structural Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin) (Germany)

    2012-11-15

    Post-translationally modified proteins make up the majority of the proteome and establish, to a large part, the impressive level of functional diversity in higher, multi-cellular organisms. Most eukaryotic post-translational protein modifications (PTMs) denote reversible, covalent additions of small chemical entities such as phosphate-, acyl-, alkyl- and glycosyl-groups onto selected subsets of modifiable amino acids. In turn, these modifications induce highly specific changes in the chemical environments of individual protein residues, which are readily detected by high-resolution NMR spectroscopy. In the following, we provide a concise compendium of NMR characteristics of the main types of eukaryotic PTMs: serine, threonine, tyrosine and histidine phosphorylation, lysine acetylation, lysine and arginine methylation, and serine, threonine O-glycosylation. We further delineate the previously uncharacterized NMR properties of lysine propionylation, butyrylation, succinylation, malonylation and crotonylation, which, altogether, define an initial reference frame for comprehensive PTM studies by high-resolution NMR spectroscopy.

  1. EPR and NMR detection of transient radicals and reaction products

    International Nuclear Information System (INIS)

    Trifunac, A.D.

    1981-01-01

    Magnetic resonance methods in radiation chemistry are illustrated. The most recent developments in pulsed EPR and NMR studies in pulse radiolysis are outlined with emphasis on the study of transient radicals and their reaction products. 12 figures

  2. A high-pressure NMR probe for aqueous geochemistry.

    Science.gov (United States)

    Pautler, Brent G; Colla, Christopher A; Johnson, Rene L; Klavins, Peter; Harley, Stephen J; Ohlin, C André; Sverjensky, Dimitri A; Walton, Jeffrey H; Casey, William H

    2014-09-08

    A non-magnetic piston-cylinder pressure cell is presented for solution-state NMR spectroscopy at geochemical pressures. The probe has been calibrated up to 20 kbar using in situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10 μL of sample in a microcoil. Initial (11)B NMR spectroscopy of the H3BO3-catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation. The inexpensive probe design doubles the current pressure range available for solution NMR spectroscopy and is particularly important to advance the field of aqueous geochemistry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Structural, vibrational, NMR, quantum chemical, DNA binding and ...

    Indian Academy of Sciences (India)

    -one oxime (HL¹) and 3-(pyridin-2-ylmethylimino)-pentan-2-one oxime (HL²) have been synthesized and characterized by elemental analysis, IR and NMR techniques. The conformational behavior was investigated using the density functional ...

  4. Structure of Coordination Complexes: The Synergy between NMR ...

    African Journals Online (AJOL)

    Cl2 and Ti(β-diketonato)2(biphen) complexes as determined by density functional theory (DFT) methods and the application of the Boltzmann equation, are in agreement with crystal structures and variable temperature NMR results. Secondly ...

  5. 13C-NMR of diterpenes with pimarane skeleton

    International Nuclear Information System (INIS)

    Garcez, W.S.; Pereira, A.L.; Silva Queiroz, P.P. da; Silva, R.S. da; Valente, L.M.M.; Peixoto, E.M.; Cunha Pinto, A. da

    1981-01-01

    The effect of substituent groups on the chemical shift of carbons using nuclear magnetic resonance spectra of carbon 13 ( 13 C-NMR) is discussed. Diterpenes having pimarane skeleton, isolated from plants of Velloziaceae family are analysed. (ARHC) [pt

  6. Contribution of proton NMR relaxation to the investigation of ...

    Indian Academy of Sciences (India)

    001 Lisboa, Portugal. *Author for correspondence. Abstract. We present in this work a review concerning wide frequency range T1 proton NMR relaxation studies performed in compounds exhibiting columnar mesophases, namely the Col ho.

  7. Interfaces in polymer nanocomposites – An NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Böhme, Ute; Scheler, Ulrich, E-mail: scheler@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden (Germany)

    2016-03-09

    Nuclear Magnetic Resonance (NMR) is applied for the investigation of polymer nanocomposites. Solid-state NMR is applied to study the modification steps to compatibilize layered double hydroxides with non-polar polymers. {sup 1}H relaxation NMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the transverse relaxation time T{sub 2} is most suited. In this presentation we report on two applications of T{sub 2} measurements under external mechanical stress. In a low-field system relaxation NMR studies are performed in-situ under uniaxial stress. High-temperature experiments in a Couette cell permit the investigation of the polymer dynamics in the melt under shear flow.

  8. Interfaces in polymer nanocomposites – An NMR study

    International Nuclear Information System (INIS)

    Böhme, Ute; Scheler, Ulrich

    2016-01-01

    Nuclear Magnetic Resonance (NMR) is applied for the investigation of polymer nanocomposites. Solid-state NMR is applied to study the modification steps to compatibilize layered double hydroxides with non-polar polymers. 1 H relaxation NMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the transverse relaxation time T 2 is most suited. In this presentation we report on two applications of T 2 measurements under external mechanical stress. In a low-field system relaxation NMR studies are performed in-situ under uniaxial stress. High-temperature experiments in a Couette cell permit the investigation of the polymer dynamics in the melt under shear flow.

  9. [Rapid analysis of suppositories by quantitative 1H NMR spectroscopy].

    Science.gov (United States)

    Abramovich, R A; Kovaleva, S A; Goriainov, S V; Vorob'ev, A N; Kalabin, G A

    2012-01-01

    Rapid analysis of suppositories with ibuprofen and arbidol by quantitative 1H NMR spectroscopy was performed. Optimal conditions for the analysis were developed. The results are useful for design of rapid methods for quality control of suppositories with different components

  10. Proton NMR relaxation in hydrous melts

    International Nuclear Information System (INIS)

    Braunstein, J.; Bacarella, A.L.; Benjamin, B.M.; Brown, L.L.; Girard, C.

    1976-01-01

    Pulse and continuous wave NMR measurements are reported for protons in hydrous melts of calcium nitrate at temperatures between -4 and 120 0 C. Although measured in different temperature ranges, spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation times appear to be nearly equal to each other and proportional to the self-diffusion coefficients of solute metal cations such as Cd 2+ . At temperatures near 50 0 C, mean Arrhenius coefficients Δ H/sub T 1 / (kcal/mol) are 7.9, 7.3, and 4.8, respectively, for melts containing 2.8, 4.0, and 8.0 moles of water per mole of calcium nitrate, compared to 4.6 kcal/mol for pure water. Temperature dependence of T 1 and T 2 in Ca(NO 3 ) 2 -2.8 H 2 O between -4 and 120 0 C are non-Arrhenius and can be represented by a Fulcher-type equation with a ''zero mobility temperature'' (T 0 ) of 225 0 K, close to the value of T 0 for solute diffusion, electrical conductance and viscosity. Resolution of the relaxation rates into correlation times for intramolecular (rotational) and intermolecular (translational) diffusional motion is discussed in terms of the Bloembergen-Purcell-Pound and more recent models for dipolar relaxation

  11. A multinuclear static NMR study of geopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Favier, Aurélie, E-mail: aurelie.favier@epfl.ch [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); Habert, Guillaume [Institute for Construction and Infrastructure Management, ETH Zurich, CH-8093 Zurich (Switzerland); Roussel, Nicolas [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); D' Espinose de Lacaillerie, Jean-Baptiste [Ecole Supérieure de Physique et de Chimie Indusrtrielles de la Ville de Paris (ESPCI), ParisTech, PSL Research University, Soft Matter Sciences and Engineering Laboratory SIMM, CNRS UMR 7615, 10 rue Vauquelin, F-75005 Paris (France)

    2015-09-15

    Geopolymers are inorganic binders obtained by alkali activation of aluminosilicates. While the structure of geopolymers is now well understood, the details of the geopolymerisation reaction and their impact on the rheology of the paste remain uncertain. In this work, we follow the elastic properties of a paste made with metakaolin and sodium silicate solution. After the first sharp increase of elastic modulus occurring a few hundred of seconds after mixing and related to the heterogeneous formation of an alumina–silicate gel with a molar ratio Si/Al < 4 located at the grains boundaries, we focus on the progressive increase in elastic modulus on a period of few hours during the setting of the geopolymer. In this study, we combine the study of rheological properties of the paste with {sup 23}Na, {sup 27}Al and {sup 29}Si static NMR measurement in order to better understand the origin of this second increase in elastic modulus. Our results show that, after a few hours, Al and Na evolution in the liquid phase are concomitant. This suggests the precipitation of an aluminosilicate phase where Al is in tetrahedral position and Na compensates the charge. Furthermore, Si speciation confirms this result and allows us to identify the precipitation of a product, which has a chemical composition close to the final composition of geopolymer. This study provides strong evidence for a heterogeneous formation of an aluminosilicate glass directly from the first gel and the silicate solution without the need for a reorganisation of Gel 1 into Gel 2.

  12. NMR-CT image and symbol phantoms

    International Nuclear Information System (INIS)

    Hongo, Syozo; Yamaguchi, Hiroshi; Takeshita, Hiroshi

    1990-01-01

    We have developed Japanese phantoms in two procedures. One is described as a mathematical expression. Another is 'symbol phantoms' in 3 dimensional picture-elements, each of which symbolize an organ name. The concept and the algorithm of the symbol phantom enables us to make a phantom for a individual in terms of all his transversal section images. We got 85 transversal section images of head and trunk parts, and those of 40 legs parts by using NMR-CT. We have made the individual phantom for computation of organ doses. The transversal section images were not so clear to identify all organs needed to dose estimation that we had to do hand-editing the shapes of organs with viewing a typical section images: we could not yet make symbol phantom in a automatic editing. Symbols were coded to be visual cords as ASCII characters. After we got the symbol phantom of the first stage, we can edit it easily using a word-processor. Symbol phantom could describe more freely the shape of organs than mathematical phantom. Symbol phantom has several advantages to be an individual phantom, but the only difficult point is how to determine its end-point as a reference man when we apply the method to build the reference man. (author)

  13. "perfecting" WATERGATE: Clean proton NMR spectra from aqueous solution

    OpenAIRE

    Adams, Ralph W.; Holroyd, Chloe M.; Aguilar Malavia, Juan; Nilsson, Mathias; Morris, Gareth A.

    2013-01-01

    A simple modification of the WATERGATE solvent suppression method greatly improves the quality of 1H NMR spectra obtainable from samples in H2O. The new method allows 1H signals to be measured even when close in chemical shift to the signal of water, as for example in the NMR spectra of carbohydrates. This journal is © 2013 The Royal Society of Chemistry.

  14. Solid-state NMR studies of nucleic acid components

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Hodgkinson, P.

    2015-01-01

    Roč. 5, č. 16 (2015), s. 12300-12310 ISSN 2046-2069 R&D Projects: GA ČR GA13-24880S Institutional support: RVO:61388963 Keywords : NMR spectroscopy * nucleic acids * solid-state NMR Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015 http://pubs.rsc.org/en/content/articlepdf/2015/ra/c4ra14404j

  15. 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 which are needed for formation evaluation by NMR well logging. NMR well logging is finding wide use in formation evaluation. The formation parameters commonly estimated were porosity, permeability, and capillary bound water. Special cases include estimation of oil viscosity, residual oil saturation, location of oil/water contact, and interpretation on whether the hydrocarbon is oil or gas.

  16. 2D NMR-spectroscopic screening reveals polyketides in ladybugs

    OpenAIRE

    Deyrup, Stephen T.; Eckman, Laura E.; McCarthy, Patrick H.; Smedley, Scott R.; Meinwald, Jerrold; Schroeder, Frank C.

    2011-01-01

    Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature’s cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior...

  17. Noninvasive detection of nanoparticle clustering by water proton NMR

    Energy Technology Data Exchange (ETDEWEB)

    Taraban, Marc B.; Truong, Huy C.; Ilavsky, Jan; DePaz, Roberto A.; Lobo, Brian; Yu, Y. Bruce

    2017-06-01

    It is shown that water proton NMR can detect uncontrolled clustering of inert nanoparticles (NPs) formulated as aqueous suspensions. The clustering of NPs causes the compartmentalization of water molecules, leading to accelerated proton spin de-coherence, and hence, much faster water transverse relaxation rates. The results suggest that water proton NMR can be used to noninvasively inspect NP products by commercial end users and researchers.

  18. 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.

  19. 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

    Roč. 51, č. 10 (2013), s. 676-681 ISSN 0749-1581 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:AV ČR(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

  20. Investigating the Mechanisms of Amylolysis of Starch Granules by Solution-State NMR

    Science.gov (United States)

    2015-01-01

    Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice starch granules are highly mobile and that during hydrothermal treatment, when the granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of starch. PMID:25815624

  1. Final Report: Characterization of Hydrogen Adsorption in Carbon-Based Materials by NMR

    International Nuclear Information System (INIS)

    Wu, Yue; Kleinhammes, Alfred

    2011-01-01

    is well suited for hydrogen storage due to its controlled microporous structure and large surface area; and (4) A new porosimetry method for evaluating the pore landscape using H2 as a probe was developed. 1H NMR can probe the nanoscale pore structure of synthesized material and can assess the pore dimension over a range covering 1.2 nm to 2.5 nm, the size that is desired for H2 adsorption. Analysis of 1H NMR spectra in conjunction with the characterization of the bonding structure of the adsorbent by 13C NMR distinguishes between a heterogeneous and homogeneous pore structure as evidenced by the work on AX21 and activated PEEK. Most of the sorbents studied are suited to hydrogen storage at low temperature (T < 100K). Of the materials investigated, only boron substituted graphite has the potential to work at higher temperatures if the boron content in the favorable planar BC3 configuration that actively contributes to adsorption can be increased.

  2. Final Report: Characterization of Hydrogen Adsorption in Carbon-Based Materials by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yue; Kleinhammes, Alfred

    2011-07-11

    activated PEEK is well suited for hydrogen storage due to its controlled microporous structure and large surface area. • A new porosimetry method for evaluating the pore landscape using H2 as a probe was developed. 1H NMR can probe the nanoscale pore structure of synthesized material and can assess the pore dimension over a range covering 1.2 nm to 2.5 nm, the size that is desired for H2 adsorption. • Analysis of 1H NMR spectra in conjunction with the characterization of the bonding structure of the adsorbent by 13C NMR distinguishes between a heterogeneous and homogeneous pore structure as evidenced by the work on AX21 and activated PEEK. • Most of the sorbents studied are suited to hydrogen storage at low temperature (T < 100K). Of the materials investigated, only boron substituted graphite has the potential to work at higher temperatures if the boron content in the favorable planar BC3 configuration that actively contributes to adsorption can be increased.

  3. Broadband rotational resonance in solid state NMR spectroscopy.

    Science.gov (United States)

    Chan, Jerry C C; Tycko, Robert

    2004-05-08

    A new technique for restoring nuclear magnetic dipole-dipole couplings under magic-angle spinning (MAS) in solid state nuclear magnetic resonance (NMR) spectroscopy is described and demonstrated. In this technique, called broadband rotational resonance (BroBaRR), the coupling between a pair of nuclear spins with NMR frequency difference close (but not necessarily equal) to the MAS frequency is restored by the application of a train of weak radio-frequency pulses at a carrier frequency close to the average of the two NMR frequencies. Phase or amplitude modulation of the pulse train at half the MAS frequency splits the carrier into sidebands close to the two NMR frequencies. The pulse train then removes offsets from the exact rotational resonance condition, leading to dipolar recoupling over a bandwidth controlled by the amplitude of the pulse train. (13)C NMR experiments on uniformly (15)N,(13)C-labeled L-valineHClH(2)O powder validate the theoretical analysis. BroBaRR will be useful in studies of molecular structures by solid state NMR, for example in the detection of long-range couplings between carbons in uniformly labeled organic and biological materials.

  4. Conjoined use of EM and NMR in RNA structure refinement.

    Directory of Open Access Journals (Sweden)

    Zhou Gong

    Full Text Available More than 40% of the RNA structures have been determined using nuclear magnetic resonance (NMR technique. NMR mainly provides local structural information of protons and works most effectively on relatively small biomacromolecules. Hence structural characterization of large RNAs can be difficult for NMR alone. Electron microscopy (EM provides global shape information of macromolecules at nanometer resolution, which should be complementary to NMR for RNA structure determination. Here we developed a new energy term in Xplor-NIH against the density map obtained by EM. We conjointly used NMR and map restraints for the structure refinement of three RNA systems—U2/U6 small-nuclear RNA, genome-packing motif (Ψ(CD2 from Moloney murine leukemia virus, and ribosome-binding element from turnip crinkle virus. In all three systems, we showed that the incorporation of a map restraint, either experimental or generated from known PDB structure, greatly improves structural precision and accuracy. Importantly, our method does not rely on an initial model assembled from RNA duplexes, and allows full torsional freedom for each nucleotide in the torsion angle simulated annealing refinement. As increasing number of macromolecules can be characterized by both NMR and EM, the marriage between the two techniques would enable better characterization of RNA three-dimensional structures.

  5. 29Si NMR and SAXS investigation of the hybrid organic-inorganic glasses obtained by consolidation of the melting gels

    Science.gov (United States)

    Jitianu, Andrei; Cadars, Sylvian; Zhang, Fan; Rodriguez, Gabriela; Picard, Quentin; Aparicio, Mario; Mosa, Jadra; Klein, Lisa C.

    2017-01-01

    This study is focused on structural characterization of hybrid glasses obtained by consolidation of melting gels. The melting gels were prepared in molar ratios of methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES) of 75%MTES-25%DMDES and 65%MTES-35%DMDES. Following consolidation, the hybrid glasses were characterized using Raman, 29Si and 13C Nuclear Magnetic Resonance (NMR) spectroscopies, synchrotron Small Angle X-Ray Scattering (SAXS) and scanning electron microscopy (SEM). Raman spectroscopy revealed the presence of Si-C bonds in the hybrid glasses and 8-membered ring structures in the Si-O-Si network. Qualitative NMR spectroscopy identified the main molecular species, while quantitative NMR data showed that the ratio of trimers (T) to dimers (D) varied between 4.6 and 3.8. Two-dimensional 29Si NMR data were used to identify two distinct types of T3 environments. SAXS data showed that the glasses are homogeneous across the nm to micrometer length scales. The scattering cross section was one thousand times lower than what is expected when phase separation occurs. The SEM images show a uniform surface without defects, in agreement with the SAXS results, which further supports that the hybrid glasses are nonporous. PMID:28262904

  6. Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as (31)P qNMR standards.

    Science.gov (United States)

    Weber, Michael; Hellriegel, Christine; Rueck, Alexander; Wuethrich, Juerg; Jenks, Peter; Obkircher, Markus

    2015-04-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that (1)H qNMR can be performed with high accuracy leading to measurement uncertainties below 1 % relative. It was even demonstrated that the combination of (1)H qNMR with metrological weighing can lead to measurement uncertainties below 0.1 % when highly pure substances are used. Although qNMR reference standards are already available as certified reference materials (CRM) providing traceability on the basis of (1)H qNMR experiments, there is an increasing demand for purity assays on phosphorylated organic compounds and metabolites requiring CRM for quantification by (31)P qNMR. Unfortunately, the number of available primary phosphorus standards is limited to a few inorganic CRM which only can be used for the analysis of water-soluble analytes but fail when organic solvents must be employed. This paper presents the concept of value assignment by (31)P qNMR measurements for the development of CRM and describes different approaches to establish traceability to primary Standard Reference Material from the National Institute of Standards and Technology (NIST SRM). Phosphonoacetic acid is analyzed as a water-soluble CRM candidate, whereas triphenyl phosphate is a good candidate for the use as qNMR reference material in organic solvents. These substances contain both nuclei, (1)H and (31)P, and the concept is to show that it is possible to indirectly quantify a potential phosphorus standard via its protons using (1)H qNMR. The same standard with its assigned purity can then be used for the quantification of an analyte via its phosphorus using (31)P qNMR. For the validation of the concept, triphenyl phosphate and phosphonoacetic acid have been used as (31)P qNMR standards to determine the purity of the analyte

  7. Development of 19F-NMR chemical shift detection of DNA B-Z equilibrium using 19F-NMR.

    Science.gov (United States)

    Nakamura, S; Yang, H; Hirata, C; Kersaudy, F; Fujimoto, K

    2017-06-28

    Various DNA conformational changes are in correlation with biological events. In particular, DNA B-Z equilibrium showed a high correlation with translation and transcription. In this study, we developed a DNA probe containing 5-trifluoromethylcytidine or 5-trifluoromethylthymidine to detect DNA B-Z equilibrium using 19 F-NMR. Its probe enabled the quantitative detection of B-, Z-, and ss-DNA based on 19 F-NMR chemical shift change.

  8. NMR-CT in muscular disorders

    International Nuclear Information System (INIS)

    Matsumura, Kiichiro; Nakano, Imaharu; Fukuda, Nobuo; Ikehira, Hiroo; Tateno, Yukio.

    1987-01-01

    Proton NMR-CT (magnetic field strength 0.1 Tesla, resonant frequency 4.5 MHz) was performed in 10 normal females and 19 Duchenne muscular dystrophy (DMD) carriers. The mean age was 39 ± 12 years for the normal females and 42 ± 6 years for the DMD carriers. In DMD carriers, there were 4 definite, 4 probable, and 11 possible carriers. T 1 (spin-lattice relaxation time) image was obtained for a slice at the buttock, mid-thigh and calf levels respectively. T 1 values were measured for the medial portion of the gluteus maximus, the vastus lateralis of the quadriceps femoris, and the gastrocnemius. The bound water fraction (BWF) was calculated from Fullerton's equation based on the fast proton diffusion model. The following results were obtained: (1) In normal females, muscle T 1 value was highest in the gastrocnemius and lowest in the gluteus maximus. (2) In DMD carriers, T 1 values of the gluteus maximus and quadriceps femoris were significantly higher than those of the normal females. There was, however, no significant difference in T 1 value of the gastrocnemius between DMD carriers and normal females. (3) In DMD carriers, BWFs of the gluteus maximus and quadriceps femoris were significantly lower than those of the normal females. (4) In DMD carriers, no significant correlation was observed between the muscle T 1 values and the serum creatine phosphokinase values. Increased tissue water content in the lower parts of the body due to gravity is considered to be the primary cause of the high T 1 value in the gastrocnemius of normal females. The presence of the degenerating muscle fibers are presumed responsible for the high T 1 value and low BWF in the proximal muscles of DMD carriers. (author)

  9. NMR-CT in muscular disorders

    International Nuclear Information System (INIS)

    Matsumura, Kiichiro; Nakano, Imaharu; Ikehira, Hiroo; Fukuda, Nobuo; Tateno, Yukio.

    1986-01-01

    Proton NMR-CT (magnetic field strength 0.1 Tesla, resonant frequency 4.5 MHz) was performed in 15 normal (NC) and 20 Duchenne muscular dystrophy (DMD) males. The age ranged from 3 to 47 years for the NC males, and 1 to 14 years for the DMD males. In the DMD group there were one subclinical stage, 4 stage 1, 6 stage 2, 4 stage 3, and 5 stage 5 or higher patients. T 1 (longitudinal relaxation) images were obtained for three slices at the buttock, midthigh, and calf levels. The T 1 values were measured for the medial portion of the gluteus maximus, the vastus lateralis of the quadriceps femoris, the adductors, the sartorius, the gracilis, and the gastrocnemius muscles. Bound water fraction (BWF) was calculated from Fullerton's equation based on the fast diffusion model. The following results were obtained: (1) In the NC group, muscle T 1 values declined gradually with maturation under the age of 10, and became constant beyond that. The average T 1 value was 280 ms for the age group between 3 and 6 years, 270 ms for 7 and 10 years, and 260 ms for those older than 10 years. (2) Muscle BWF increased with maturation in the NC group. (3) In the DMD group, T 1 values were initially higher than normal (300 ms), declined rapidly with the progress of the disease, and reached the same low level as the subcutaneous fat (190 ms). (4) This decrease of T 1 value in DMD was not uniform for all muscles, being most prominent in the gluteus maximus and least so in the sartorius and gracilis. (5) In the early stages of DMD, the BWF was lower than normal. (J.P.N.)

  10. Timing and related artifacts in multidimensional NMR

    International Nuclear Information System (INIS)

    Marion, Dominique

    2012-01-01

    The information content of multidimensional NMR spectra is limited by the presence of several kinds of artifacts that originate from incorrect timing of evolution periods. The objective of this review is to provide tools for successful implementation of published pulse sequences, in which timing and pulse compensations are often implicit. We will analyze the constraints set by the use of Fourier transformation, the spin precession during rectangular or shaped pulses, the Bloch-Siegert effects due to pulse on other spins and the delay introduced by the filters for the acquisition dimension. A frequency dependent phase correction or an incorrect scaling of the first data point leads to baseline offsets or curvature due to the properties of the Fourier transform. Because any r.f. pulse has a finite length, chemical shift is always active during excitation, flip-back, inversion, and refocusing pulses. Rectangular or selective shaped pulses can be split into three periods: an ideal rotation surrounded by two chemical shift evolution periods, which should be subtracted from the adjacent delays to avoid linear phase correction. Bloch-Siegert effects originate from irradiation at frequencies near those observed in the spectrum and can lead to phase or frequency shifts. They can be minimized by simultaneous irradiation on both sides of the observed spins. In terms of timing, the very end of the pulse sequence the acquisition behaves differently since the data are filtered by either analog or digital means. This additional delay is filter and spectrometer specific and should be tuned to minimize the required phase correction. Combined together, all these adjustments lead to perfectly phased spectra with flat baseline and no peak shifts or distortion. (author)

  11. 31P NMR saturation-transfer and 13C NMR kinetic studies of glycolytic regulation during anaerobic and aerobic glycolysis

    International Nuclear Information System (INIS)

    Campbell-Burk, S.L.; den Hollander, J.A.; Alger, J.R.; Shulman, R.G.

    1987-01-01

    31 P NMR saturation-transfer techniques have been employed in glucose-gown derepressed yeast to determine unidirectional fluxes in the upper part of the Embden-Meyerhof-Parnas pathway. The experiments were performed during anaerobic and aerobic glycolysis by saturating the ATP/sub γ/ resonances and monitoring changes in the phosphomonoester signals from glucose 6-phosphate and fructose 1,6-bisphosphate. These experiments were supplemented with 13 C NMR measurements of glucose utilization rates and 13 C NMR label distribution studies. Combined with data obtained previously from radioisotope measurement, these 31 P and 13 C NMR kinetic studies allowed estimation of the net glycolytic flow in addition to relative flows through phosphofructokinase (PFK) and Fru-1,6-P 2 ase during anaerobic and aerobic glycolysis. The 31 P NMR saturation-transfer results are consistent with previous results obtained from measurements of metabolite levels, radioisotope data, and 13 C NMR studies, providing additional support for in vivo measurement of the flows during glycolysis

  12. Efficient DNP NMR of Membrane Proteins: Sample Preparation Protocols, Sensitivity, and Radical Location

    Science.gov (United States)

    Liao, Shu Y.; Lee, Myungwoon; Wang, Tuo; Sergeyev, Ivan V.; Hong, Mei

    2016-01-01

    Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~4 fold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105–160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes. PMID:26873390

  13. Bentonite pore structure based on SAXS, chloride exclusion and NMR studies

    International Nuclear Information System (INIS)

    Muurinen, A.; Carlsson, T.

    2013-11-01

    Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Na montmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm 3 . The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T 1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm 3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 % and non-interlayer porosity of 12 %. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 A. From the montmorillonite surface area 98 % was interlayer and 2 % non-interlayer. Evaluation of the interlayer and non

  14. Novel Techniques for Pulsed Field Gradient NMR Measurements

    Science.gov (United States)

    Brey, William Wallace

    Pulsed field gradient (PFG) techniques now find application in multiple quantum filtering and diffusion experiments as well as in magnetic resonance imaging and spatially selective spectroscopy. Conventionally, the gradient fields are produced by azimuthal and longitudinal currents on the surfaces of one or two cylinders. Using a series of planar units consisting of azimuthal and radial current elements spaced along the longitudinal axis, we have designed gradient coils having linear regions that extend axially nearly to the ends of the coil and to more than 80% of the inner radius. These designs locate the current return paths on a concentric cylinder, so the coils are called Concentric Return Path (CRP) coils. Coils having extended linear regions can be made smaller for a given sample size. Among the advantages that can accrue from using smaller coils are improved gradient strength and switching time, reduced eddy currents in the absence of shielding, and improved use of bore space. We used an approximation technique to predict the remaining eddy currents and a time-domain model of coil performance to simulate the electrical performance of the CRP coil and several reduced volume coils of more conventional design. One of the conventional coils was designed based on the time-domain performance model. A single-point acquisition technique was developed to measure the remaining eddy currents of the reduced volume coils. Adaptive sampling increases the dynamic range of the measurement. Measuring only the center of the stimulated echo removes chemical shift and B_0 inhomogeneity effects. The technique was also used to design an inverse filter to remove the eddy current effects in a larger coil set. We added pulsed field gradient and imaging capability to a 7 T commercial spectrometer to perform neuroscience and embryology research and used it in preliminary studies of binary liquid mixtures separating near a critical point. These techniques and coil designs will find

  15. Accurate, fully-automated NMR spectral profiling for metabolomics.

    Directory of Open Access Journals (Sweden)

    Siamak Ravanbakhsh

    Full Text Available Many diseases cause significant changes to the concentrations of small molecules (a.k.a. metabolites that appear in a person's biofluids, which means such diseases can often be readily detected from a person's "metabolic profile"-i.e., the list of concentrations of those metabolites. This information can be extracted from a biofluids Nuclear Magnetic Resonance (NMR spectrum. However, due to its complexity, NMR spectral profiling has remained manual, resulting in slow, expensive and error-prone procedures that have hindered clinical and industrial adoption of metabolomics via NMR. This paper presents a system, BAYESIL, which can quickly, accurately, and autonomously produce a person's metabolic profile. Given a 1D 1H NMR spectrum of a complex biofluid (specifically serum or cerebrospinal fluid, BAYESIL can automatically determine the metabolic profile. This requires first performing several spectral processing steps, then matching the resulting spectrum against a reference compound library, which contains the "signatures" of each relevant metabolite. BAYESIL views spectral matching as an inference problem within a probabilistic graphical model that rapidly approximates the most probable metabolic profile. Our extensive studies on a diverse set of complex mixtures including real biological samples (serum and CSF, defined mixtures and realistic computer generated spectra; involving > 50 compounds, show that BAYESIL can autonomously find the concentration of NMR-detectable metabolites accurately (~ 90% correct identification and ~ 10% quantification error, in less than 5 minutes on a single CPU. These results demonstrate that BAYESIL is the first fully-automatic publicly-accessible system that provides quantitative NMR spectral profiling effectively-with an accuracy on these biofluids that meets or exceeds the performance of trained experts. We anticipate this tool will usher in high-throughput metabolomics and enable a wealth of new applications of

  16. Comparing pharmacophore models derived from crystallography and NMR ensembles

    Science.gov (United States)

    Ghanakota, Phani; Carlson, Heather A.

    2017-11-01

    NMR and X-ray crystallography are the two most widely used methods for determining protein structures. Our previous study examining NMR versus X-Ray sources of protein conformations showed improved performance with NMR structures when used in our Multiple Protein Structures (MPS) method for receptor-based pharmacophores (Damm, Carlson, J Am Chem Soc 129:8225-8235, 2007). However, that work was based on a single test case, HIV-1 protease, because of the rich data available for that system. New data for more systems are available now, which calls for further examination of the effect of different sources of protein conformations. The MPS technique was applied to Growth factor receptor bound protein 2 (Grb2), Src SH2 homology domain (Src-SH2), FK506-binding protein 1A (FKBP12), and Peroxisome proliferator-activated receptor-γ (PPAR-γ). Pharmacophore models from both crystal and NMR ensembles were able to discriminate between high-affinity, low-affinity, and decoy molecules. As we found in our original study, NMR models showed optimal performance when all elements were used. The crystal models had more pharmacophore elements compared to their NMR counterparts. The crystal-based models exhibited optimum performance only when pharmacophore elements were dropped. This supports our assertion that the higher flexibility in NMR ensembles helps focus the models on the most essential interactions with the protein. Our studies suggest that the "extra" pharmacophore elements seen at the periphery in X-ray models arise as a result of decreased protein flexibility and make very little contribution to model performance.

  17. 1H-NMR, 1H-NMR T2-edited, and 2D-NMR in bipolar disorder metabolic profiling.

    Science.gov (United States)

    Sethi, Sumit; Pedrini, Mariana; Rizzo, Lucas B; Zeni-Graiff, Maiara; Mas, Caroline Dal; Cassinelli, Ana Cláudia; Noto, Mariane N; Asevedo, Elson; Cordeiro, Quirino; Pontes, João G M; Brasil, Antonio J M; Lacerda, Acioly; Hayashi, Mirian A F; Poppi, Ronei; Tasic, Ljubica; Brietzke, Elisa

    2017-12-01

    The objective of this study was to identify molecular alterations in the human blood serum related to bipolar disorder, using nuclear magnetic resonance (NMR) spectroscopy and chemometrics. Metabolomic profiling, employing 1 H-NMR, 1 H-NMR T 2 -edited, and 2D-NMR spectroscopy and chemometrics of human blood serum samples from patients with bipolar disorder (n = 26) compared with healthy volunteers (n = 50) was performed. The investigated groups presented distinct metabolic profiles, in which the main differential metabolites found in the serum sample of bipolar disorder patients compared with those from controls were lipids, lipid metabolism-related molecules (choline, myo-inositol), and some amino acids (N-acetyl-L-phenyl alanine, N-acetyl-L-aspartyl-L-glutamic acid, L-glutamine). In addition, amygdalin, α-ketoglutaric acid, and lipoamide, among other compounds, were also present or were significantly altered in the serum of bipolar disorder patients. The data presented herein suggest that some of these metabolites differentially distributed between the groups studied may be directly related to the bipolar disorder pathophysiology. The strategy employed here showed significant potential for exploring pathophysiological features and molecular pathways involved in bipolar disorder. Thus, our findings may contribute to pave the way for future studies aiming at identifying important potential biomarkers for bipolar disorder diagnosis or progression follow-up.

  18. NMR structure of the N-terminal domain of the replication initiator protein DnaA

    Energy Technology Data Exchange (ETDEWEB)

    Wemmer, David E.; Lowery, Thomas J.; Pelton, Jeffrey G.; Chandonia, John-Marc; Kim, Rosalind; Yokota, Hisao; Wemmer, David E.

    2007-08-07

    DnaA is an essential component in the initiation of bacterial chromosomal replication. DnaA binds to a series of 9 base pair repeats leading to oligomerization, recruitment of the DnaBC helicase, and the assembly of the replication fork machinery. The structure of the N-terminal domain (residues 1-100) of DnaA from Mycoplasma genitalium was determined by NMR spectroscopy. The backbone r.m.s.d. for the first 86 residues was 0.6 +/- 0.2 Angstrom based on 742 NOE, 50 hydrogen bond, 46 backbone angle, and 88 residual dipolar coupling restraints. Ultracentrifugation studies revealed that the domain is monomeric in solution. Features on the protein surface include a hydrophobic cleft flanked by several negative residues on one side, and positive residues on the other. A negatively charged ridge is present on the opposite face of the protein. These surfaces may be important sites of interaction with other proteins involved in the replication process. Together, the structure and NMR assignments should facilitate the design of new experiments to probe the protein-protein interactions essential for the initiation of DNA replication.

  19. FTIR AND NMR STUDIES OF ADSORBED CETHYLTRIMETHYLAMMONIUM CHLORIDE IN MCM-41 MATERIALS

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2010-06-01

    Full Text Available The high use of surface-active agents (surfactants by industry and households today leads to environmental pollution, therefore treatments are required to remove such substances from the environment. One of the important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41 and its modified product of MCM41-TMCS were used to adsorb cationic surfactants, cethyltrimethylammonium chloride, CTAC. FTIR and NMR methods were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane (MCM41-TMCS. Both unmodified and modified MCM-41 can adsorb the surfactant. The interaction of CTAC with MCM-41 was mostly the electrostatic interaction between the electropositive end of the surfactant and MCM-41, whereas in modified MCM-41 hydrophobic interactions become more dominant. These hydrophobic interactions appear however to involve the methyl groups on the head group of the surfactant interacting with the modified surface.   Keywords: FTIR, NMR, adsorbed CTAC, MCM-41 materials

  20. β-NMR investigation of the vortex lattice near the interface of silver and Pr1.85Ce0.15CuO thin films

    Science.gov (United States)

    Saadaoui, H.; MacFarlane, W. A.; Salman, Z.; Morris, G. D.; Chow, K. H.; Fan, I.; Fournier, P.; Hossain, M. D.; Keeler, T. A.; Kreitzman, S. R.; Levy, C. D. P.; Mansour, A. I.; Miller, R. I.; Parolin, T. J.; Pearson, M. R.; Song, Q.; Wang, D.; Kiefl, R. F.

    2009-04-01

    In this paper, we report observation of the vortex lattice above the surface of high-temperature superconductors Pr2-xCexCuO using beta-detected NMR ( β-NMR) of Li+8 implanted in a 40 nm thick Ag overlayer. The resonance in Ag broadens dramatically below the transition temperature Tc as expected from the vortex lattice in the underlying superconductor. However, the lineshape is nearly symmetric with the absence of a high-field tail and exhibits a slight positive shift of the average field below Tc.

  1. Application of fluorine NMR for structure identification of steroids.

    Science.gov (United States)

    Ampt, Kirsten A M; Aspers, Ruud L E G; Jaeger, Martin; Geutjes, Pepijn E T J; Honing, Maarten; Wijmenga, Sybren S

    2011-05-01

    Fluorinated steroids were examined using 1D and 2D homo- and heteronuclear (19)F NMR, such as (19)F-(1) H and (19)F-(13)C. The utilization of fluorine NMR accounted for spectral simplification and resulted in a straightforward pathway for the determination of structures including the configuration of these compounds; these steroids present an illustrative example for other types of fluorinated compounds, which are increasingly encountered in drug discovery. The potential of (19)F NMR is elaborated on in detail for two compounds containing diastereotopic fluorines with different coupling patterns. The analysis of the coupling patterns and the through-space interactions resulted in the determination of the structure and configuration. Heteronuclear correlation experiments, i.e. (19)F-(1)H HETCOR, (19)F-(13)C HMQC and HMBC, and (19)F-(1)H HOESY, were applied to determine first the relative stereochemistry and then the molecular configuration at C4 and C5 of a steroidal compound bearing a fused three-membered ring with two fluorine substituents. These examples proved (19)F NMR to be a useful addition to the extensively used (1)H and (13)C NMR within structure elucidation and configuration determination of small molecules. Copyright © 2011 John Wiley & Sons, Ltd.

  2. Theoretical Modeling of 99 Tc NMR Chemical Shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Gabriel B.; Andersen, Amity; Washton, Nancy M.; Chatterjee, Sayandev; Levitskaia, Tatiana G.

    2016-09-06

    Technetium (Tc) displays a rich chemistry due to the wide range of oxidation states (from -I to +VII) and ability to form coordination compounds. Determination of Tc speciation in complex mixtures is a major challenge, and 99Tc NMR spec-troscopy is widely used to probe chemical environments of Tc in odd oxidation states. However interpretation of the 99Tc NMR data is hindered by the lack of reference compounds. DFT computations can help fill this gap, but to date few com-putational studies have focused on 99Tc NMR of compounds and complexes. This work systematically evaluates the inclu-sion small percentages of Hartree-Fock exchange correlation and relativistic effects in DFT computations to support in-terpretation of the 99Tc NMR spectra. Hybrid functionals are found to perform better than their pure GGA counterparts, and non-relativistic calculations have been found to generally show a lower mean absolute deviation from experiment. Overall non-relativistic PBE0 and B3PW91 calculations are found to most accurately predict 99Tc NMR chemical shifts.

  3. Chirp echo Fourier transform EPR-detected NMR

    Science.gov (United States)

    Wili, Nino; Jeschke, Gunnar

    2018-04-01

    A new ultra-wide band (UWB) pulse EPR method is introduced for observing all nuclear frequencies of a paramagnetic center in a single shot. It is based on burning spectral holes with a high turning angle (HTA) pulse that excites forbidden transitions and subsequent detection of the hole pattern by a chirp echo. We term this method Chirp Echo Epr SpectroscopY (CHEESY)-detected NMR. The approach is a revival of FT EPR-detected NMR. It yields similar spectra and the same type of information as electron-electron double resonance (ELDOR)-detected NMR, but with a multiplex advantage. We apply CHEESY-detected NMR in Q band to nitroxides and correlate the hyperfine spectrum to the EPR spectrum by varying the frequency of the HTA pulse. Furthermore, a selective π pulse before the HTA pulse allows for detecting hyperfine sublevel correlations between transitions of one nucleus and for elucidating the coupling regime, the same information as revealed by the HYSCORE experiment. This is demonstrated on hexaaquamanganese(II). We expect that CHEESY-detected NMR is generally applicable to disordered systems and that our results further motivate the development of EPR spectrometers capable of coherent UWB excitation and detection, especially at higher fields and frequencies.

  4. The GNAT: A new tool for processing NMR data.

    Science.gov (United States)

    Castañar, Laura; Poggetto, Guilherme Dal; Colbourne, Adam A; Morris, Gareth A; Nilsson, Mathias

    2018-02-02

    The GNAT (General NMR Analysis Toolbox) is a free and open-source software package for processing, visualising, and analysing NMR data. It supersedes the popular DOSY Toolbox, which has a narrower focus on diffusion NMR. Data import of most common formats from the major NMR platforms is supported, as well as a GNAT generic format. Key basic processing of NMR data (e.g., Fourier transformation, baseline correction, and phasing) is catered for within the program, as well as more advanced techniques (e.g., reference deconvolution and pure shift FID reconstruction). Analysis tools include DOSY and SCORE for diffusion data, ROSY T 1 /T 2 estimation for relaxation data, and PARAFAC for multilinear analysis. The GNAT is written for the MATLAB® language and comes with a user-friendly graphical user interface. The standard version is intended to run with a MATLAB installation, but completely free-standing compiled versions for Windows, Mac, and Linux are also freely available. © 2018 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons Ltd.

  5. Time domain NMR evaluation of poly(vinyl alcohol) xerogels

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Elton Jorge da Rocha; Cavalcante, Maxwell de Paula; Tavares, Maria Ines Bruno, E-mail: mibt@ima.ufrj.br [Universidade Federal do Rio de Janeiro (IMA/UFRJ), Rio de Janeiro, RJ (Brazil). Centro de Tecnologia. Instituto de Macromoleculas Professora Eloisa Mano

    2016-05-15

    Poly(vinyl alcohol) (PVA)-based chemically cross-linked xerogels, both neat and loaded with nanoparticulate hydrophilic silica (SiO{sub 2}), were obtained and characterized mainly through time domain NMR experiments (TD-NMR). Fourier-transform infrared (FT-IR) and wide angle X-ray diffraction (WAXD) analyses were employed as secondary methods. TD-NMR, through the interpretation of the spin-lattice relaxation constant values and related information, showed both cross-linking and nanoparticle influences on PVA matrix. SiO{sub 2} does not interact chemically with the PVA chains, but has effect on its molecular mobility, as investigated via TD-NMR. Apparent energy of activation, spin-lattice time constant and size of spin domains in the sample have almost linear dependence with the degree of cross-linking of the PVA and are affected by the addition of SiO{sub 2}. These three parameters were derived from a single set of TD-NMR experiments, which demonstrates the versatility of the technique for characterization of inorganic-organic hybrid xerogels, an important class of materials. (author)

  6. Selected topics in solution-phase biomolecular NMR spectroscopy

    Science.gov (United States)

    Kay, Lewis E.; Frydman, Lucio

    2017-05-01

    Solution bio-NMR spectroscopy continues to enjoy a preeminent role as an important tool in elucidating the structure and dynamics of a range of important biomolecules and in relating these to function. Equally impressive is how NMR continues to 'reinvent' itself through the efforts of many brilliant practitioners who ask increasingly demanding and increasingly biologically relevant questions. The ability to manipulate spin Hamiltonians - almost at will - to dissect the information of interest contributes to the success of the endeavor and ensures that the NMR technology will be well poised to contribute to as yet unknown frontiers in the future. As a tribute to the versatility of solution NMR in biomolecular studies and to the continued rapid advances in the field we present a Virtual Special Issue (VSI) that includes over 40 articles on various aspects of solution-state biomolecular NMR that have been published in the Journal of Magnetic Resonance in the past 7 years. These, in total, help celebrate the achievements of this vibrant field.

  7. High resolution deuterium NMR studies of bacterial metabolism

    International Nuclear Information System (INIS)

    Aguayo, J.B.; Gamcsik, M.P.; Dick, J.D.

    1988-01-01

    High resolution deuterium NMR spectra were obtained from suspensions of five bacterial strains: Escherichia coli, Clostridium perfringens, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus aureus. Deuterium-labeled D-glucose at C-1, C-2, and C-6 was used to monitor dynamically anaerobic metabolism. The flux of glucose through the various bacterial metabolic pathways could be determined by following the disappearance of glucose and the appearance of the major end products in the 2H NMR spectrum. The presence of both labeled and unlabeled metabolites could be detected using 1H NMR spectroscopy since the proton resonances in the labeled species are shifted upfield due to an isotopic chemical shift effect. The 1H-1H scalar coupling observed in both the 2H and 1H NMR spectra was used to assign definitively the resonances of labeled species. An increase in the intensity of natural abundance deuterium signal of water can be used to monitor pathways in which a deuteron is lost from the labeled metabolite. The steps in which label loss can occur are outlined, and the influence these processes have on the ability of 2H NMR spectroscopy to monitor metabolism are assessed

  8. NMR Characterization of Flavanone Naringenin 7-O-Glycoside Diastereomer

    Directory of Open Access Journals (Sweden)

    SUN Li-juan

    2017-12-01

    Full Text Available To discriminate R and S flavanone glycoside using NMR, the mixture of R and S naringenin 7-O-glycoside was first isolated from Gleditsia sinensis. 1H and 13C NMR data of the mixture were recorded with 1H NMR, 13C NMR, 1H-1H COSY, 1H-13C HSQC and 1H-13C HMBC in DMSO-d6 solution. The two diastereomers were then separated with chiral chromatographic isolation, with their absolute configurations determined by circular dichroism. To avoid the disturbance of protons from glucose residues to dihydroflavonoid, 1H NMR spectra were acquired for pure R and S naringenin 7-O-glycoside and their mixture in CD3CN. The two diastereomers showed the largest proton chemical shift differences at the end group of glucose residue (H-1" with a chemical shift difference of 9.4 Hz. The OH-5 proton showed a chemical shift difference of 5.8 Hz. The chemical shift of the three protons on ring C were all influenced by configuration.

  9. Study of cultured fibroblasts in vivo using NMR

    Energy Technology Data Exchange (ETDEWEB)

    Karczmar, G.S.

    1984-08-01

    The goal was to study the compartmentation of phosphorylated glycolytic intermediates in intact Chicken Embryo Fibroblasts (CEFs) using /sup 31/P NMR at 109 MHz. A technique for maintaining functional cells at high densities in an NMR magnet is described. Signals were detected from cytoplasmic inorganic phosphate (P/sub i/), ATP, NAD, NADH, phosphorylcholine and phosphorylethanolamine. The effect of external glucose on cytoplasmic pools of phosphates was studied. When cells were perfused with glucose-free medium the rate of glycolysis decreased, the amplitudes of the ATP resonances decreased, and the P/sub i/ intensity increased. The quantity of NMR-detectable P/sub i/ produced was significantly greater than the quantity of NMR-detectable ATP which was lost. Experiments with /sup 32/P labeled P/sub i/ showed that as the concentration of glucose in the medium was increase, the amount of phosphate sequestered in the cells increased. We conclude that there is a pool of P/sub i/ which is not detected by high resolution NMR and that the size of this pool increases as the rate of glycolysis increase. Longtitudinal relaxation times of intracellular phosphates in normal, transformed, and primary CEFs were measured. The results demonstrate that relaxation times of phosphates are sensitive to structural and metabolic changes which occur when cells are grown in culture. 59 references. 31 figures.

  10. Recovery of Underwater Resonances by Magnetization Transferred NMR Spectroscopy (RECUR-NMR)

    Science.gov (United States)

    Liu, Maili; Tang, Huiru; Nicholson, Jeremy K.; Lindon, John C.

    2001-11-01

    A method for detecting small molecule NMR resonances under a water peak in biological samples is presented. After high-efficiency solvent suppression using double WATERGATE, either a TOCSY- or ROESY-based coherence transfer sequence is applied to reestablish the resonances close to, or under, water through magnetization transfer using scalar or dipolar coupling, respectively. The use of the TOCSY and ROESY methods ensures an in-phase magnetization transfer, which makes the new approach readily extended for the measurement of transverse relaxation times, internuclear ROEs, and ROE buildup rates. An extension of the new approach for J-resolved spectroscopy is also presented and tested using a sample of human blood plasma.

  11. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A

    1979-01-01

    Progress in Surface and Membrane Science, Volume 12 covers the advances in the study of surface and membrane science. The book discusses the topographical differentiation of the cell surface; the NMR studies of model biological membrane system; and an irreversible thermodynamic approach to energy coupling in mitochondria and chloroplasts. The text also describes water at surfaces; the nature of microemulsions; and the energy principle in the stability of interfaces. Biochemists, physicists, chemical engineers, and people involved in surface and coatings research will find the book invaluable.

  12. Elucidation of meso- and microporosity in soil components with 129-Xe NMR spectroscopy of adsorbed xenon

    Science.gov (United States)

    Filimonova, Svetlana; Nossov, Andrey; Knicker, Heike; Kögel-Knabner, Ingrid

    2010-05-01

    Soil meso- and micropores (2-50 nm and bio-macromolecules. Natural soil particle size fractions were obtained from a non-allophanic Andosol and from Arenosol, i.e. soils containing charred residues and also characterised by a high content of Al oxides (case of the Andosol). DOM sorption on the studied Al oxides occurred inhomogeneously as it was inferred from the existence of the "empty" pores and the pores coated with OM. The latter were evidenced by the different Xe adsorption enthalpies estimated from the temperature dependences of the chemical shift. The increased sensitivity of the HP 129-Xe NMR allowed us detecting micropores in the charcoals, where the N2 adsorption method underestimated porosity due to the restricted diffusion of N2 at 77 K. The observed differences between the HP and TP 129-Xe patterns were explained by the slow diffusion of xenon within an interconnected but highly constricted pore system of the charcoals. The estimated width of those constricted pore openings was of the order of one or two diameters of the Xe atom. Similar "bottle neck" effects may also exist in the natural soil particle size fractions, as it was inferred from the increased pore access for Xe adsorption performed at elevated pressures (2-4 bar). The unusually large 129-Xe shifts (up to 170 ppm) detected for the for the H2O2-treated clay fractions of the Andosol (Bw horizon) coincided with their large specific surface areas(up to 220 m2/g) and were attributed to the pores formed by agglomerates of the nano-sized Al - humus complexes with contribution from the charred residues. Micropores found in the Arenosol fractions were attributed to the charred residues. Briefly, 129-Xe NMR spectroscopy shows its potential for studying soil meso- and micropores due to: i) higher sensitivity for probing micropores within polymeric organic structures, e.g. charcoals, as compared to the N2 adsorption; ii) possibility to use elevated pressures of the adsorbate for increasing the pore

  13. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T

    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...

  14. Observation of isolated carbon atoms and the study of their mobility on Pt clusters by NMR

    International Nuclear Information System (INIS)

    Wang, P.; Ansermet, J.; Slichter, C.P.; Sinfelt, J.H.

    1985-01-01

    The authors have used NMR to determine the structure of surface species after the C-C bond scission of adsorbed acetylene and ethylene on Pt clusters produced by heating the samples to 690 K. They have found the species to be predominantly isolated carbon atoms adsorbed on Pt surfaces. They have studied the mobility of adsorbed carbon atoms from motional narrowing of the 13 C line shapes and motion-induced shortening of the spin-lattice relaxation times. They have found that the carbon atoms on Pt clusters are very mobile, their activation energy of 7 +- 1 kcal/mole for translational motion being less than half that of CO on Pt clusters

  15. High field NMR spectroscopy and FTICR mass spectrometry: powerful discovery tools for the molecular level characterization of marine dissolved organic matter from the South Atlantic Ocean

    Science.gov (United States)

    Hertkorn, N.; Harir, M.; Koch, B. P.; Michalke, B.; Grill, P.; Schmitt-Kopplin, P.

    2012-01-01

    Non target high resolution organic structural spectroscopy of marine dissolved organic matter (DOM) isolated on 27 November 2008 by means of solid phase extraction (SPE) from four different depths in the South Atlantic Ocean off the Angola coast (3.1° E; -17.7° S; Angola basin) provided molecular level information of complex unknowns with unprecedented coverage and resolution. The sampling was intended to represent major characteristic oceanic regimes of general significance: 5 m (FISH; near surface photic zone), 48 m (FMAX; fluorescence maximum), 200 m (upper mesopelagic zone) and 5446 m (30 m above ground). 800 MHz proton (1H) nuclear magnetic resonance (NMR) 1H NMR, spectra were least affected by fast and differential transverse NMR relaxation and produced at first similar looking, rather smooth bulk NMR envelopes reflecting intrinsic averaging from massive signal overlap. Visibly resolved NMR signatures were most abundant in surface DOM but contributed at most a few percent to the total 1H NMR integral and were mainly limited to unsaturated and singly oxygenated carbon chemical environments. The relative abundance and variance of resolved signatures between samples was maximal in the aromatic region; in particular, the aromatic resolved NMR signature of the deep ocean sample at 5446 m was considerably different from that of all other samples. When scaled to equal total NMR integral, 1H NMR spectra of the four marine DOM samples revealed considerable variance in abundance for all major chemical environments across the entire range of chemical shift. Abundance of singly oxygenated CH units and acetate derivatives declined from surface to depth whereas aliphatics and carboxyl-rich alicyclic molecules (CRAM) derived molecules increased in abundance. Surface DOM contained a remarkably lesser abundance of methyl esters than all other marine DOM, likely a consequence of photodegradation from direct exposure to sunlight. All DOM showed similar overall 13C NMR

  16. De novo protein structure determination using sparse NMR data

    International Nuclear Information System (INIS)

    Bowers, Peter M.; Strauss, Charlie E.M.; Baker, David

    2000-01-01

    We describe a method for generating moderate to high-resolution protein structures using limited NMR data combined with the ab initio protein structure prediction method Rosetta. Peptide fragments are selected from proteins of known structure based on sequence similarity and consistency with chemical shift and NOE data. Models are built from these fragments by minimizing an energy function that favors hydrophobic burial, strand pairing, and satisfaction of NOE constraints. Models generated using this procedure with ∼1 NOE constraint per residue are in some cases closer to the corresponding X-ray structures than the published NMR solution structures. The method requires only the sparse constraints available during initial stages of NMR structure determination, and thus holds promise for increasing the speed with which protein solution structures can be determined

  17. Applications of saturation transfer difference NMR in biological systems.

    Science.gov (United States)

    Bhunia, Anirban; Bhattacharjya, Surajit; Chatterjee, Subhrangsu

    2012-05-01

    The method of saturation transfer difference (STD) nuclear magnetic resonance (NMR) is an indispensable NMR tool in drug discovery. It identifies binding epitope(s) at the atomic resolution of small molecule ligands (e.g. organic drugs, peptides and oligosaccharides), while interacting with their receptors, such as proteins and/or nucleic acids. The method is widely used to screen active drug molecules, simultaneously ranking them in a qualitative way. STD NMR is highly successful for a variety of high molecular weight systems, such as whole viruses, platelets, intact cells, lipopolysaccharide micelles, membrane proteins, recombinant proteins and dispersion pigments. Modifications of STD pulse programs using (13)C and (15)N nuclei are now used to overcome the signal overlapping that occurs with more complex structures. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. NMRFx Processor: a cross-platform NMR data processing program

    International Nuclear Information System (INIS)

    Norris, Michael; Fetler, Bayard; Marchant, Jan; Johnson, Bruce A.

    2016-01-01

    NMRFx Processor is a new program for the processing of NMR data. Written in the Java programming language, NMRFx Processor is a cross-platform application and runs on Linux, Mac OS X and Windows operating systems. The application can be run in both a graphical user interface (GUI) mode and from the command line. Processing scripts are written in the Python programming language and executed so that the low-level Java commands are automatically run in parallel on computers with multiple cores or CPUs. Processing scripts can be generated automatically from the parameters of NMR experiments or interactively constructed in the GUI. A wide variety of processing operations are provided, including methods for processing of non-uniformly sampled datasets using iterative soft thresholding. The interactive GUI also enables the use of the program as an educational tool for teaching basic and advanced techniques in NMR data analysis.

  19. Experimental demonstration of quantum contextuality on an NMR qutrit

    International Nuclear Information System (INIS)

    Dogra, Shruti; Dorai, Kavita; Arvind

    2016-01-01

    We experimentally test quantum contextuality of a single qutrit using NMR. The contextuality inequalities based on nine observables developed by Kurzynski et al. are first reformulated in terms of traceless observables which can be measured in an NMR experiment. These inequalities reveal the contextuality of almost all single-qutrit states. We demonstrate the violation of the inequality on four different initial states of a spin-1 deuterium nucleus oriented in a liquid crystal matrix, and follow the violation as the states evolve in time. We also describe and experimentally perform a single-shot test of contextuality for a subclass of qutrit states whose density matrix is diagonal in the energy basis. - Highlights: • A contextuality inequality for a single qutrit was designed using traceless observables. • The violation of the inequality was experimentally demonstrated using NMR. • A single-shot test was experimentally performed for a subclass of diagonal qutrit states.

  20. NMR imaging of cell phone radiation absorption in brain tissue

    Science.gov (United States)

    Gultekin, David H.; Moeller, Lothar

    2013-01-01

    A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance frequency shift of hydrogen protons in brain tissue. This proposed application of NMR thermometry offers sufficient spatial and temporal resolution to characterize the hot spots from absorbed cell phone radiation in aqueous media and biological tissues. Specific absorption rate measurements averaged over 1 mg and 10 s in the brain tissue cover the total absorption volume. Reference measurements with fiber optic temperature sensors confirm the accuracy of the NMR thermometry. PMID:23248293

  1. NMRFx Processor: a cross-platform NMR data processing program.

    Science.gov (United States)

    Norris, Michael; Fetler, Bayard; Marchant, Jan; Johnson, Bruce A

    2016-08-01

    NMRFx Processor is a new program for the processing of NMR data. Written in the Java programming language, NMRFx Processor is a cross-platform application and runs on Linux, Mac OS X and Windows operating systems. The application can be run in both a graphical user interface (GUI) mode and from the command line. Processing scripts are written in the Python programming language and executed so that the low-level Java commands are automatically run in parallel on computers with multiple cores or CPUs. Processing scripts can be generated automatically from the parameters of NMR experiments or interactively constructed in the GUI. A wide variety of processing operations are provided, including methods for processing of non-uniformly sampled datasets using iterative soft thresholding. The interactive GUI also enables the use of the program as an educational tool for teaching basic and advanced techniques in NMR data analysis.

  2. NMR investigation of actinide (4) beta-diketonates

    International Nuclear Information System (INIS)

    Shcherbakova, L.L.; Mishin, V.Ya.; Rubtsov, E.M.

    1984-01-01

    NMR spectra of dipivaloylmethanates (DPM) of tetravalent thorium, uranium, neptunium and plutonium in various solvents in the 153-353 K temperature range have been studied. The mentioned coordination compounds, as well as acetylacetonates, in solution have coordination number eight and do not form solvates with polar molecules. They are stable to hydrolysis and to moderate radiation loads. In the case of uranium- and neptunium compounds a photochemical instability is detected, which could be used for synthesis of previously unknown actinyl dipivaloylmethanates. According to low-temperature NMR spectra two types of stoichiometric softness of the compounds studied are found. A problem of contact and pseudocontact contributions to the paramagnetic shifts in actinide (4) β-diketonates is discussed. An exact characteristic behaviour of the NMR-shifts of signals of DPM tret-butyl groups of the β-diketonates under considerafion is of interest from the analytical viewpoint

  3. The installation of a commercial resistive NMR imager

    International Nuclear Information System (INIS)

    Smith, M.A.; Best, J.J.K.; Douglas, R.H.B.; Kean, D.M.

    1984-01-01

    It has been demonstrated that a relatively low-cost resistive NMR imager can be installed in a normal hospital environment without many major or expensive modifications. The magnet can be adjusted to give adequate uniformity and there is sufficient RF shielding to give good quality clinical images. The fringe field of the magnet of this system, which operates at the lowest field strength of any commercial NMR imager, does not present a problem to imaging unit staff. The long term reliability and detailed specifications with regard to image quality have yet to be determined. These will be determined whilst the imager is being used for clinical studies as part of the national clinical evaluation of NMR imaging supported by the Medical Research Council. (author)

  4. NMR-Metabolic Methodology in the Study of GM Foods

    Directory of Open Access Journals (Sweden)

    Irene D’Amico

    2010-01-01

    Full Text Available The 1H-NMR methodology used in the study of genetically modified (GM foods is discussed. Transgenic lettuce (Lactuca sativa cv "Luxor" over-expressing the Arabidopsis KNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars present in leaves of conventional and GM lettuce were monitored by NMR and quantified at two developmental stages. The NMR spectra did not reveal any difference in metabolite composition between the GM lettuce and the wild type counterpart. Statistical analyses of metabolite variables highlighted metabolism variation as a function of leaf development as well as the transgene. A main effect of the transgene was in altering sugar metabolism.

  5. 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.

  6. Automated high-resolution NMR with a sample changer

    International Nuclear Information System (INIS)

    Wade, C.G.; Johnson, R.D.; Philson, S.B.; Strouse, J.; McEnroe, F.J.

    1989-01-01

    Within the past two years, it has become possible to obtain high-resolution NMR spectra using automated commercial instrumentation. Software control of all spectrometer functions has reduced most of the tedious manual operations to typing a few computer commands or even making selections from a menu. Addition of an automatic sample changer is the next natural step in improving efficiency and sample throughput; it has a significant (and even unexpected) impact on how NMR laboratories are run and how it is taught. Such an instrument makes even sophisticated experiments routine, so that people with no previous exposure to NMR can run these experiments after a training session of an hour or less. This A/C Interface examines the impact of such instrumentation on both the academic and the industrial laboratory

  7. Clinical NMR imaging of the brain: 140 cases

    International Nuclear Information System (INIS)

    Bydder, G.M.; Steiner, R.E.; Young, I.R.; Hall, A.S.; Thomas, D.J.; Marshall, J.; Pallis, C.A.; Legg, N.J.

    1982-01-01

    Cranial nuclear magnetic resonance (NMR) scans were performed on 13 healthy volunteers and 140 patients with a broad spectrum of neurologic disease and compared with x-ray computed tomography (CT) scans. Advantages of NMR imaging include the high level of gray-white matter contrast, lack of bone artifact, variety of possible sequences, transverse, sagittal, and coronal imaging, sensitivity to pathologic change, and lack of known hazard. Disadvantages include lack of bone detail, limited spatial resolution, lack of contrast agents, and cost. Promising directions for future clinical research include developmental neurology, tissue characterization with T 1 and T 2 , assessment of blood flow, and the development of contrast agents. Much more detailed evaluation will be required, but NMR seems to be a potentially important addition to existing techniques of neurologic diagnosis

  8. Carbohydrate-protein interactions: a 3D view by NMR.

    Science.gov (United States)

    Roldós, Virginia; Cañada, F Javier; Jiménez-Barbero, Jesús

    2011-05-02

    This review focuses on the application of NMR methods for understanding, at the molecular and atomic levels, the diverse mechanisms by which sugar molecules are recognised by the binding sites of lectins, antibodies and enzymes. Given the intrinsic chemical natures of sugars and their flexibility, it is well established that NMR parameters should be complemented by computational methods in attempts to unravel the structural and conformational features of the molecular recognition process unambiguously. We therefore aim here to describe new and significant advances in the knowledge of carbohydrate-protein interactions, obtained by employing state-of-the-art NMR and molecular modelling. We have not attempted to prepare an exhaustive review but have tried to focus on describing the key aspects that should be considered when tackling a problem within this research topic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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)

  10. NMRFx Processor: a cross-platform NMR data processing program

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Michael; Fetler, Bayard [One Moon Scientific, Inc. (United States); Marchant, Jan [University of Maryland Baltimore County, Howard Hughes Medical Institute (United States); Johnson, Bruce A., E-mail: bruce.johnson@asrc.cuny.edu [One Moon Scientific, Inc. (United States)

    2016-08-15

    NMRFx Processor is a new program for the processing of NMR data. Written in the Java programming language, NMRFx Processor is a cross-platform application and runs on Linux, Mac OS X and Windows operating systems. The application can be run in both a graphical user interface (GUI) mode and from the command line. Processing scripts are written in the Python programming language and executed so that the low-level Java commands are automatically run in parallel on computers with multiple cores or CPUs. Processing scripts can be generated automatically from the parameters of NMR experiments or interactively constructed in the GUI. A wide variety of processing operations are provided, including methods for processing of non-uniformly sampled datasets using iterative soft thresholding. The interactive GUI also enables the use of the program as an educational tool for teaching basic and advanced techniques in NMR data analysis.

  11. Thermometry of hot spot using NMR for hyperthermia

    International Nuclear Information System (INIS)

    Amemiya, Yoshifumi; Kamimura, Yoshitsugu

    1983-01-01

    Lately noticed hyperthermia in cancer therapy requires non-invasive measurement of the temperature at the warmed site in the deep portion of human body. Nuclear magnetic relaxation time of NMR is also usable for cancer diagnosis. For coordination of these two techniques, it was judged suitable to measure temperature by NMR so that cancer diagnosis and treatment and evaluation of therapeutic effect might be incorporated into one system. This report dealt with concrete procedures of measuring the temperature of deep portions by NMR. Computations revealed that the coefficient of temperature of the thermal equilibrium magnetization was useful, that magnetic field focusing was the most effective imaging technique and that temperature rise in areas about 2 cm in radius could be measured without large errors. (Chiba, N.)

  12. Multinuclear NMR studies of hemoproteins and their model compounds

    International Nuclear Information System (INIS)

    Lee, H.C.

    1988-01-01

    Nuclear magnetic resonance (NMR) in both solution and solid state has been used to study the active site structure of various hemoproteins, and the nature of the iron-oxygen bond in oxyhemoglobin. The first iron-57 NMR spectra of a metalloprotein, carbonmonoxymyoglobin, has been obtained, yielding the isotropic chemical shift, the anisotropy of the chemical shielding tensor and the rotational correlation time of the protein. The oxygen-17 NMR signals from CO ligands bound to oxygen-transport hemoproteins are much narrower than expected, and the lineshape is non-Lorentzian. The results indicate that the unusual linewidths and lineshapes originate from the multiexponential nature of quadrupolar relaxation outside of the extreme narrowing limit, permitting determinations of the oxygen-17 nuclear quadrupole coupling constants and the rotational correlation time of the proteins

  13. NMR of geophysical drill cores with a mobile Halbach scanner

    International Nuclear Information System (INIS)

    Talnishnikh, E.

    2007-01-01

    This thesis is devoted to a mobile NMR with an improved Halbach scanner. This is a lightweight tube-shaped magnet with sensitive volume larger and a homogeneity of the magnetic field higher than the previous prototype version. The improved Halbach scanner is used for analysis of water-saturated drill cores and plugs with diameters up to 60 mm. To provide the analysis, the standard 1D technique with the CPMG sequence as well as 2D correlation experiments were successfully applied and adapted to study properties of fluid-saturated sediments. Afterwards the Halbach scanner was calibrated to fast non-destructive measurements of porosity, relaxation time distributions, and estimation of permeability. These properties can be calculated directly from the NMR data using the developed methodology. Any independent measurements of these properties with other methods are not needed. One of the main results of this work is the development of a new NMR on-line core scanner for measurements of porosity in long cylindrical and semi cylindrical drill cores. Also dedicated software was written to operate the NMR on-line core scanner. The physical background of this work is the study of the diffusion influence on transverse relaxation. The diffusion effect in the presence of internal gradients in porous media was probed by 1D and 2D experiments. The transverse relaxation time distributions obtained from 1D and from 2D experiments are comparable but different in fine details. Two new methodologies were developed based on the results of this study. First is the methodology quantifying the influence of diffusion in the internal gradients of water-saturated sediments on transverse relaxation from 2D correlation experiments. The second one is the correction of the permeability estimation from the NMR data taking in account the influence of the diffusion. Furthermore, PFG NMR technique was used to study restricted diffusion in the same kind of samples. Preliminary results are reported

  14. NMR crystallography of α-poly(L-lactide).

    Science.gov (United States)

    Pawlak, Tomasz; Jaworska, Magdalena; Potrzebowski, Marek J

    2013-03-07

    A complementary approach that combines NMR measurements, analysis of X-ray and neutron powder diffraction data and advanced quantum mechanical calculations was employed to study the α-polymorph of L-polylactide. Such a strategy, which is known as NMR crystallography, to the best of our knowledge, is used here for the first time for the fine refinement of the crystal structure of a synthetic polymer. The GIPAW method was used to compute the NMR shielding parameters for the different models, which included the α-PLLA structure obtained by 2-dimensional wide-angle X-ray diffraction (WAXD) at -150 °C (model M1) and at 25 °C (model M2), neutron diffraction (WAND) measurements (model M3) and the fully optimized geometry of the PLLA chains in the unit cell with defined size (model M4). The influence of changes in the chain conformation on the (13)C σ(ii) NMR shielding parameters is shown. The correlation between the σ(ii) and δ(ii) values for the M1-M4 models revealed that the M4 model provided the best fit. Moreover, a comparison of the experimental (13)C NMR spectra with the spectra calculated using the M1-M4 models strongly supports the data for the M4 model. The GIPAW method, via verification using NMR measurements, was shown to be capable of the fine refinement of the crystal structures of polymers when coarse X-ray diffraction data for powdered samples are available.

  15. NMR of geophysical drill cores with a mobile Halbach scanner

    Energy Technology Data Exchange (ETDEWEB)

    Talnishnikh, E.

    2007-08-21

    This thesis is devoted to a mobile NMR with an improved Halbach scanner. This is a lightweight tube-shaped magnet with sensitive volume larger and a homogeneity of the magnetic field higher than the previous prototype version. The improved Halbach scanner is used for analysis of water-saturated drill cores and plugs with diameters up to 60 mm. To provide the analysis, the standard 1D technique with the CPMG sequence as well as 2D correlation experiments were successfully applied and adapted to study properties of fluid-saturated sediments. Afterwards the Halbach scanner was calibrated to fast non-destructive measurements of porosity, relaxation time distributions, and estimation of permeability. These properties can be calculated directly from the NMR data using the developed methodology. Any independent measurements of these properties with other methods are not needed. One of the main results of this work is the development of a new NMR on-line core scanner for measurements of porosity in long cylindrical and semi cylindrical drill cores. Also dedicated software was written to operate the NMR on-line core scanner. The physical background of this work is the study of the diffusion influence on transverse relaxation. The diffusion effect in the presence of internal gradients in porous media was probed by 1D and 2D experiments. The transverse relaxation time distributions obtained from 1D and from 2D experiments are comparable but different in fine details. Two new methodologies were developed based on the results of this study. First is the methodology quantifying the influence of diffusion in the internal gradients of water-saturated sediments on transverse relaxation from 2D correlation experiments. The second one is the correction of the permeability estimation from the NMR data taking in account the influence of the diffusion. Furthermore, PFG NMR technique was used to study restricted diffusion in the same kind of samples. Preliminary results are reported

  16. MetAssimulo:Simulation of Realistic NMR Metabolic Profiles

    Directory of Open Access Journals (Sweden)

    De Iorio Maria

    2010-10-01

    Full Text Available Abstract Background Probing the complex fusion of genetic and environmental interactions, metabolic profiling (or metabolomics/metabonomics, the study of small molecules involved in metabolic reactions, is a rapidly expanding 'omics' field. A major technique for capturing metabolite data is 1H-NMR spectroscopy and this yields highly complex profiles that require sophisticated statistical analysis methods. However, experimental data is difficult to control and expensive to obtain. Thus data simulation is a productive route to aid algorithm development. Results MetAssimulo is a MATLAB-based package that has been developed to simulate 1H-NMR spectra of complex mixtures such as metabolic profiles. Drawing data from a metabolite standard spectral database in conjunction with concentration information input by the user or constructed automatically from the Human Metabolome Database, MetAssimulo is able to create realistic metabolic profiles containing large numbers of metabolites with a range of user-defined properties. Current features include the simulation of two groups ('case' and 'control' specified by means and standard deviations of concentrations for each metabolite. The software enables addition of spectral noise with a realistic autocorrelation structure at user controllable levels. A crucial feature of the algorithm is its ability to simulate both intra- and inter-metabolite correlations, the analysis of which is fundamental to many techniques in the field. Further, MetAssimulo is able to simulate shifts in NMR peak positions that result from matrix effects such as pH differences which are often observed in metabolic NMR spectra and pose serious challenges for statistical algorithms. Conclusions No other software is currently able to simulate NMR metabolic profiles with such complexity and flexibility. This paper describes the algorithm behind MetAssimulo and demonstrates how it can be used to simulate realistic NMR metabolic profiles with

  17. Structural properties of carbon nanotubes derived from 13C NMR

    KAUST Repository

    Abou-Hamad, E.

    2011-10-10

    We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled carbon nanotubes with diameters in the range from 0.7 to 100 nm and with number of walls from 1 to 90. We provide models on how diameter and the number of nanotube walls influence NMR linewidth and line position. Both models are supported by theoretical calculations. Increasing the diameter D, from the smallest investigated nanotube, which in our study corresponds to the inner nanotube of a double-walled tube to the largest studied diameter, corresponding to large multiwalled nanotubes, leads to a 23.5 ppm diamagnetic shift of the isotropic NMR line position δ. We show that the isotropic line follows the relation δ = 18.3/D + 102.5 ppm, where D is the diameter of the tube and NMR line position δ is relative to tetramethylsilane. The relation asymptotically tends to approach the line position expected in graphene. A characteristic broadening of the line shape is observed with the increasing number of walls. This feature can be rationalized by an isotropic shift distribution originating from different diamagnetic shielding of the encapsulated nanotubes together with a heterogeneity of the samples. Based on our results, NMR is shown to be a nondestructive spectroscopic method that can be used as a complementary method to, for example, transmission electron microscopy to obtain structural information for carbon nanotubes, especially bulk samples.

  18. A model of the complex between human beta-microseminoprotein and CRISP-3 based on NMR data

    DEFF Research Database (Denmark)

    Ghasriani, Houman; Fernlund, Per; Udby, Lene

    2008-01-01

    MSP and CRISP-3 with multidimensional NMR. (15)N-HSQC spectra show substantial differences between free and complexed hMSP. Using several 3D-NMR spectra of triply labeled hMSP in complex with a recombinant N-terminal domain of CRISP-3, most of the backbone of hMSP could be assigned. The data show...... that only one side of hMSP, comprising beta-strands 1, 4, 5, and 8 are affected by the complex formation, indicating that beta-strands 1 and 8 form the main binding surface. Based on this we present a tentative structure for the hMSP-CRISP-3 complex using the known crystal structure of triflin as a model...

  19. Structure and function of the Juxta membrane domain of the human epidermal growth factor receptor by NMR spectroscopy

    International Nuclear Information System (INIS)

    Choowongkomon, Kiattawee; Carlin, Cathleen; Sonnichsen, Frank D.

    2005-10-01

    The epidermal growth factor receptor (EGFR) is a member of the receptor tyrosine kinase family involved in the regulation of cellular proliferation and differentiation. Its juxta membrane domain (JX), the region located between the transmembrane and kinase domains, plays important roles in receptor trafficking since both basolateral sorting in polarized epithelial cells and lysosomal sorting signals are identified in this region. In order to understand the regulation of these signals, we characterized the structural properties of recombinant JX domain in dodecyl phosphocholine detergent (DPC) by nuclear magnetic resonance (NMR) spectroscopy. In DPC micelles, structures derived from NMR data showed three amphipathic, helical segments. Two equivalent average structural models on the surface of micelles were obtained that differ only in the relative orientation between the first and second helices. Our data suggests that the activity of sorting signals may be regulated by their membrane association and restricted accessibility in the intact receptor

  20. 1H NMR spectroscopy-based interventional metabolic phenotyping

    DEFF Research Database (Denmark)

    Lauridsen, Michael B; Bliddal, Henning; Christensen, Robin

    2010-01-01

    -up with assessments of disease activity (DAS-28) and 1H NMR spectroscopy of plasma samples. Discriminant analysis provided evidence that the metabolic profiles predicted disease severity. Cholesterol, lactate, acetylated glycoprotein, and lipid signatures were found to be candidate biomarkers for disease severity.......0007). However, after 31 days of optimized therapy, the two patient groups were not significantly different (P=0.91). The metabolic profiles of both groups of RA patients were different from the healthy subjects. 1H NMR-based metabolic phenotyping of plasma samples in patients with RA is well suited...

  1. NMR analysis of silk for the interpretation of ancient history

    International Nuclear Information System (INIS)

    Chujo, Riichiro

    1998-01-01

    The aim of this paper is the characterization of archaeological silk with the aid of nuclear magnetic resonance (NMR). In this paper the nucleus is confined to 13C as a stable isotope carbon which is the most basic element in organic compounds. Among the stable carbon isotopes 12C is the most abundant but it has no magnetic moment and the natural abundance of 13C is only 1.108% and this isotope is frequently used in NMR due to its non-zero magnetic moment

  2. Recent progress in NMR microscopy towards cellular imaging

    International Nuclear Information System (INIS)

    Cho, Z.H.; Ahn, C.B.; Juh, S.C.; Friedenberg, R.M.; Fraser, S.E.; Jacobs, R.E.

    1990-01-01

    Recent advances in NMR microscopy based on fundamental physical parameters and experimental factors are discussed. We consider fundamental resolution limits due to molecular diffusion and the experimental system bandwidth, as well as practical resolution limits arising from poor signal-to-noise ratio due to small imaging voxel size and finite line broadening due to signal attenuation brought about by diffusion. Several microscopic imaging pulse sequences are presented and applied to elucidating cellular imaging problems such as the cell lineage patterns in Xenopus laevis embryos. Experimental results obtained with 7.0 T NMR microscopy system are presented. (author)

  3. Use of NMR in profiling of cocaine seizures

    DEFF Research Database (Denmark)

    Pagano, Bruno; Lauri, Ilaria; De Tito, Stefano

    2013-01-01

    Cocaine is the most widely used illicit drug, and its origin is always the focus of intense investigation aimed at identifying the trafficking routes. Since NMR represents a unique methodology for performing chemical identification and quantification, here it is proposed a strategy based on (1)H...... NMR spectral analysis in conjunction with multivariate analysis to identify the chemical "fingerprint" of cocaine samples, and to link cocaine samples based on this information. The most relevant spectral regions containing the fingerprint have been identified: δH 0.86-0.96, 1.50-1.56, 5.90-5.93, 6...

  4. NMR of mercury in porous coal and silica gel

    International Nuclear Information System (INIS)

    Kasperovich, V.S.; Charnaya, E.V.; Tien, C.; Wur, C.S.

    2003-01-01

    Temperature dependences of the integral intensity and NMR signals Knight shift in 199 Hg nuclei are measured for liquid and solid mercury introduced into the porous coal and silica gel. The decrease in the crystallization completion temperature and small temperature hysteresis (from 4 up to 9 K) between melting and crystallization are identified. Mercury melting temperature in pores coincided with melting temperature of the bulk mercury. NMR signal from crystalline mercury under conditions of limited geometry was observed for the first time. It is ascertained that Knight shift for mercury in the pores both in liquid and crystalline phases is lesser than for the bulk mercury [ru

  5. Probing Spin Crossover in a Solution by Paramagnetic NMR Spectroscopy.

    Science.gov (United States)

    Pavlov, Alexander A; Denisov, Gleb L; Kiskin, Mikhail A; Nelyubina, Yulia V; Novikov, Valentin V

    2017-12-18

    Spin transitions in spin-crossover compounds are now routinely studied in the solid state by magnetometry; however, only a few methods exist for studies in solution. The currently used Evans method, which relies on NMR spectroscopy to measure the magnetic susceptibility, requires the availability of a very pure sample of the paramagnetic compound and its exact concentration. To overcome these limitations, we propose an alternative NMR-based technique for evaluating spin-state populations by only using the chemical shifts of a spin-crossover compound; those can be routinely obtained for a solution that contains unknown impurities and paramagnetic admixtures or is contaminated otherwise.

  6. NMR studies on antiferromagnetism in alkali-electro-sodalite

    International Nuclear Information System (INIS)

    Tou, H.; Maniwa, Y.; Mizoguchi, K.; Damjanovic, L.; Srdanov, V.I.

    2001-01-01

    We report 27 Al-NMR and DC-magnetic susceptibility measurements on recently discovered alkali-electro-sodalite (AES, A=Sodium, Potassium). AES is known to be a Mott insulator consisting of a body-centered-cubic lattice of F-centers. 27 Al-NMR measurements demonstrate that SES (S=Sodium) and PES (P=Potassium) undergo an antiferromagnetic transition around T N ∼48 and 70 K, respectively. Magnetic properties, especially on the temperature dependence of the susceptibility, seem to be quite sensitive to the size of the F-centers

  7. Determination of Polybutadiene Unsaturation Content in Thermal and Thermo-Oxidative Degradation Processes by NMR

    Directory of Open Access Journals (Sweden)

    Farshid Ziaee

    2013-01-01

    Full Text Available The unsaturation content of various polybutadiene (PBD types of 1,4-cis, 1,4-trans and 1,2-vinyl isomers with different molecular weights was investigated. An important parameter for unsaturation content of polybutadiene would be the determination of olefnic and aliphatic contents for three types of isomers. For this purpose, proton and carbon nuclear magnetic resonance spectroscopy methods were employed for determination of 1,4-cis, 1,4-trans and 1,2-vinyl contents. A change of adjustable parameter of NMR software was made for accurate integrals giving better results. The accuracy in calculation of low molecular weight PBD, surface area of chain end group decreased in aliphatic region. Furthermore, the changing of unsaturation content versus time was considered for 1,2-PBD and 1,4-PBD in thermal degradation conditions at 250°C. NMR results showed that during heating, the unsaturation content decreased for 1,2-PBD and was not changed for 1,4-PBD. In fact, the basic factor responsible for changing of unsaturation content in thermal degradation of PBD may be due to the presence of 1,2-vinyl isomer. Finally, changing in unsaturation content versus time was observed for 1,2-PBD and 1,4-PBD in thermo-oxidative degradation conditions at 100°C. The NMR results showed that at extended time, the unsaturation content decreased for 1,4-PBD and was not changed for 1,2-PBD. Moreover, the basic factor for changes in unsaturation content in thermo-oxidative degradation of PBD is due to the presence of 1,4-cis and 1,4-trans isomers.

  8. Weak self-association of cytochrome c peroxidase molecules observed by paramagnetic NMR

    Energy Technology Data Exchange (ETDEWEB)

    Schilder, Jesika; Ubbink, Marcellus, E-mail: m.ubbink@chem.leidenuniv.nl [Leiden University, Gorlaeus Laboratories, Leiden Institute of Chemistry (Netherlands)

    2016-05-15

    There is growing experimental evidence that many proteins exhibit a tendency for (ultra)weak homo- or hetero- oligomerization interactions. With the development of paramagnetic relaxation enhancement NMR spectroscopy it has become possible to characterize weak complexes experimentally and even detect complexes with affinities in the 1–25 mM range. We present evidence for a weak complex between cytochrome c peroxidase (CcP) molecules. In a previous study, we attached nitroxide based spin labels at three positions on CcP with the intent of observing intramolecular PRE effects. However, several intermolecular PRE effects were also observed suggesting a weak self-association between CcP molecules. The CcP–CcP complex was characterized using paramagnetic NMR and protein docking. The interaction occurs between the surface that is also part of the stereo-specific binding site for its physiological partner, cytochrome c (Cc), and several small, positively charged patches on the “back” of CcP. The CcP–CcP complex is not a stereo-specific complex. It is a dynamic ensemble of orientations, characteristic of an encounter state. The contact areas resemble those observed for CcP molecules in crystals. The CcP–CcP complex formation competes with that of the CcP-Cc complex. However, the affinity for Cc is much larger and thus it is expected that, under physiological conditions, auto-inhibition will be limited.Graphical AbstractA weak self-association between cytochrome c peroxidase molecules was characterized using paramagnetic NMR.

  9. A portable single-sided magnet system for remote NMR measurements of pulmonary function

    Science.gov (United States)

    Mikayel, Dabaghyan; Iga, Muradyan; James, Butler; Eric, Frederick; Feng, Zhou; Angelos, Kyriazis; Charles, Hardin; Samuel, Patz; Mirko, Hrovat

    2014-01-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). PMID:24953556

  10. A portable single-sided magnet system for remote NMR measurements of pulmonary function.

    Science.gov (United States)

    Dabaghyan, Mikayel; Muradyan, Iga; Hrovat, Alan; Butler, James; Frederick, Eric; Zhou, Feng; Kyriazis, Angelos; Hardin, Charles; Patz, Samuel; Hrovat, Mirko

    2014-12-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). Copyright © 2014 John Wiley & Sons, Ltd.

  11. A community resource of experimental data for NMR / X-ray crystal structure pairs.

    Science.gov (United States)

    Everett, John K; Tejero, Roberto; Murthy, Sarath B K; Acton, Thomas B; Aramini, James M; Baran, Michael C; Benach, Jordi; Cort, John R; Eletsky, Alexander; Forouhar, Farhad; Guan, Rongjin; Kuzin, Alexandre P; Lee, Hsiau-Wei; Liu, Gaohua; Mani, Rajeswari; Mao, Binchen; Mills, Jeffrey L; Montelione, Alexander F; Pederson, Kari; Powers, Robert; Ramelot, Theresa; Rossi, Paolo; Seetharaman, Jayaraman; Snyder, David; Swapna, G V T; Vorobiev, Sergey M; Wu, Yibing; Xiao, Rong; Yang, Yunhuang; Arrowsmith, Cheryl H; Hunt, John F; Kennedy, Michael A; Prestegard, James H; Szyperski, Thomas; Tong, Liang; Montelione, Gaetano T

    2016-01-01

    We have developed an online NMR / X-ray Structure Pair Data Repository. The NIGMS Protein Structure Initiative (PSI) has provided many valuable reagents, 3D structures, and technologies for structural biology. The Northeast Structural Genomics Consortium was one of several PSI centers. NESG used both X-ray crystallography and NMR spectroscopy for protein structure determination. A key goal of the PSI was to provide experimental structures for at least one representative of each of hundreds of targeted protein domain families. In some cases, structures for identical (or nearly identical) constructs were determined by both NMR and X-ray crystallography. NMR spectroscopy and X-ray diffraction data for 41 of these "NMR / X-ray" structure pairs determined using conventional triple-resonance NMR methods with extensive sidechain resonance assignments have been organized in an online NMR / X-ray Structure Pair Data Repository. In addition, several NMR data sets for perdeuterated, methyl-protonated protein samples are included in this repository. As an example of the utility of this repository, these data were used to revisit questions about the precision and accuracy of protein NMR structures first outlined by Levy and coworkers several years ago (Andrec et al., Proteins 2007;69:449-465). These results demonstrate that the agreement between NMR and X-ray crystal structures is improved using modern methods of protein NMR spectroscopy. The NMR / X-ray Structure Pair Data Repository will provide a valuable resource for new computational NMR methods development. © 2015 The Protein Society.

  12. NMR spectroscopy applied to the eye: Drugs and metabolic studies

    International Nuclear Information System (INIS)

    Saether, Oddbjoern

    2005-01-01

    NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

  13. NMR spectroscopy applied to the eye: Drugs and metabolic studies

    Energy Technology Data Exchange (ETDEWEB)

    Saether, Oddbjoern

    2005-07-01

    NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

  14. Adiabatic Low-Pass J Filters for Artifact Suppression in Heteronuclear NMR

    DEFF Research Database (Denmark)

    Meier, Sebastian; Benie, Andrew J; Duus, Jens Øllgaard

    2009-01-01

    NMR artifact purging: Modern NMR experiments depend on efficient coherence transfer pathways for their sensitivity and on suppression of undesired pathways leading to artifacts for their spectral clarity. A novel robust adiabatic element suppresses hard-to-get-at artifacts....

  15. 8Li β-NMR study of epitaxial LixCoO2 films

    Science.gov (United States)

    Sugiyama, J.; Harada, M.; Oki, H.; Shiraki, S.; Hitosugi, T.; Ofer, O.; Salman, Z.; Song, Q.; Wang, D.; Saadaoui, H.; Morris, G. D.; Chow, K. H.; MacFarlane, W. A.; Kiefl, R. F.

    2014-12-01

    In order to investigate the diffusive motion of Li+ in a thin film electrode material for Li-ion batteries, we have measured β-NMR spectra of 8Li+ ions implanted into epitaxial films of Li0.7CoO2 and LiCoO2 in the temperature range between 10 and 310 K. Below 100 K, the spin-lattice relaxation rate (1/T1) in the Li0.7CoO2 film increased with decreasing temperature, indicating the appearance and evolution of localized magnetic moments, as observed with μ+SR. As temperature is increased from 100 K, 1/T1 starts to increase above ~ 200 K, where both Li- NMR and μ+SR also sensed an increase in 1/T1 due to Li-diffusion. Interestingly, such diffusive behavior was found to depend on the implantation energy, possibly because the surface of the film is decomposed due to chemical instability of the Li0.7CoO2 phase in air. Such diffusive behavior was not observed for the LiCoO2 film up to 310 K.

  16. Electronic characterization of lithographically patterned microcoils for high sensitivity NMR detection.

    Science.gov (United States)

    Demas, Vasiliki; Bernhardt, Anthony; Malba, Vince; Adams, Kristl L; Evans, Lee; Harvey, Christopher; Maxwell, Robert S; Herberg, Julie L

    2009-09-01

    Nuclear magnetic resonance (NMR) offers a non-destructive, powerful, structure-specific analytical method for the identification of chemical and biological systems. The use of radio frequency (RF) microcoils has been shown to increase the sensitivity in mass-limited samples. Recent advances in micro-receiver technology have further demonstrated a substantial increase in mass sensitivity [D.L. Olson, T.L. Peck, A.G. Webb, R.L. Magin, J.V. Sweedler, High-resolution microcoil H-1-NMR for mass-limited, nanoliter-volume samples, Science 270 (5244) (1995) 1967-1970]. Lithographic methods for producing solenoid microcoils possess a level of flexibility and reproducibility that exceeds previous production methods, such as hand winding microcoils. This paper presents electrical characterizations of RF microcoils produced by a unique laser lithography system that can pattern three dimensional surfaces and compares calculated and experimental results to those for wire wound RF microcoils. We show that existing optimization conditions for RF coil design still hold true for RF microcoils produced by lithography. Current lithographic microcoils show somewhat inferior performance to wire wound RF microcoils due to limitations in the existing electroplating technique. In principle, however, when the pitch of the RF microcoil is less than 100mum lithographic coils should show comparable performance to wire wound coils. In the cases of larger pitch, wire cross sections can be significantly larger and resistances lower than microfabricated conductors.

  17. [Interactions between proteins and cation exchange adsorbents analyzed by NMR and hydrogen/deuterium exchange technique].

    Science.gov (United States)

    Wang, Kang; Hao, Dongxia; Qi, Shuting; Ma, Guanghui

    2014-09-01

    In silico acquirement of the accurate residue details of protein on chromatographic media is a bottleneck in protein chromatography separation and purification. Here we developed a novel approach by coupling with H/D exchange and nuclear magnetic resonance to observe hen egg white lysozyme (HEWL) unfolding behavior adsorbed on cation exchange media (SP Sepharose FF). Analysis of 1D 1H-NMR shows that protein unfolding accelerated H/D exchange rate, leading to more loss of signal of amide hydrogen owing to exposure of residues and the more unfolding of protein. Analysis of two-dimensional hydrogen-hydrogen total correlation spectroscopy shows that lysozyme lost more signals and experienced great unfolding during its adsorption on media surface. However, for several distinct fragments, the protection degrees varied, the adsorbed lysozyme lost more signal intensity and was less protected at disorder structures (coil, bend, and turn), but was comparatively more protected against exchange at secondary structure domains (α-helix, β-sheet). Finally, the binding site was determined by electrostatic calculations using computer simulation methods in conjunction with hydrogen deuterium labeled protein and NMR. This study would help deeply understand the microscopic mechanism of protein chromatography and guide the purposely design of chromatographic process and media. Moreover, it also provide an effective tool to study the protein and biomaterials interaction in other applications.

  18. Recent developments in solution nuclear magnetic resonance (NMR)-based molecular biology.

    Science.gov (United States)

    Ziarek, Joshua J; Baptista, Diego; Wagner, Gerhard

    2018-01-01

    Visualizing post-translational modifications, conformations, and interaction surfaces of protein structures at atomic resolution underpins the development of novel therapeutics to combat disease. As computational resources expand, in silico calculations coupled with experimentally derived structures and functional assays have led to an explosion in structure-based drug design (SBDD) with several compounds in clinical trials. It is increasingly clear that "hidden" transition-state structures along activation trajectories can be harnessed to develop novel classes of allosteric inhibitors. The goal of this mini-review is to empower the clinical researcher with a general knowledge of the strengths and weaknesses of nuclear magnetic resonance (NMR) spectroscopy in molecular medicine. Although NMR can determine protein structures at atomic resolution, its unrivaled strength lies in sensing subtle changes in a nuclei's chemical environment as a result of intrinsic conformational dynamics, solution conditions, and binding interactions. These can be recorded at atomic resolution, without explicit structure determination, and then incorporated with static structures or molecular dynamics simulations to produce a complete biological picture.

  19. FTIR AND NMR STUDIES OF ADSORBED TRITON X-114 IN MCM-41 MATERIALS

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2010-06-01

    Full Text Available One source of water pollutions is caused by the high use of surface-active agents (surfactants by industries and households. As a consequence, it is required to remove such substances from the environment One of the important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41 and its modification MCM41-TMCS were used to adsorb nonionic surfactant, Triton X-114. FTIR and NMR methods were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane (MCM41-TMCS. Both unmodified and modified MCM-41 can adsorb the surfactant. The amount adsorbed in the unmodified material is higher than that in the modified one. The interaction of Triton X-114 with MCM-41 was hydrogen bonding between the silanol groups in MCM-41 and hydroxyl groups of Triton X-114. For modified samples, Triton X-114 interacted with alkylsilyl groups mostly through hydrophobic interaction. It is more likely that the interaction was through C12, C13, C26 and C27 of Triton X-114.    Keywords: FTIR, NMR, adsorbed Triton X-114, MCM-41 materials

  20. LC-NMR Technique in the Analysis of Phytosterols in Natural Extracts

    Directory of Open Access Journals (Sweden)

    Štěpán Horník

    2013-01-01

    Full Text Available The ability of LC-NMR to detect simultaneously free and conjugated phytosterols in natural extracts was tested. The advantages and disadvantages of a gradient HPLC-NMR method were compared to the fast composition screening using SEC-NMR method. Fractions of free and conjugated phytosterols were isolated and analyzed by isocratic HPLC-NMR methods. The results of qualitative and quantitative analyses were in a good agreement with the literature data.

  1. NMR Spectroscopy in Glass Science: A Review of the Elements

    Directory of Open Access Journals (Sweden)

    Randall Youngman

    2018-03-01

    Full Text Available The study of inorganic glass structure is critically important for basic glass science and especially the commercial development of glasses for a variety of technological uses. One of the best means by which to achieve this understanding is through application of solid-state nuclear magnetic resonance (NMR spectroscopy, which has a long and interesting history. This technique is element specific, but highly complex, and thus, one of the many inquiries made by non-NMR specialists working in glass science is what type of information and which elements can be studied by this method. This review presents a summary of the different elements that are amenable to the study of glasses by NMR spectroscopy and provides examples of the type of atomic level structural information that can be achieved. It serves to inform the non-specialist working in glass science and technology about some of the benefits and challenges involved in the study of inorganic glass structure using modern, readily-available NMR methods.

  2. Quantitative produced water analysis using mobile 1H NMR

    Science.gov (United States)

    Wagner, Lisabeth; Kalli, Chris; Fridjonsson, Einar O.; May, Eric F.; Stanwix, Paul L.; Graham, Brendan F.; Carroll, Matthew R. J.; Johns, Michael L.

    2016-10-01

    Measurement of oil contamination of produced water is required in the oil and gas industry to the (ppm) level prior to discharge in order to meet typical environmental legislative requirements. Here we present the use of compact, mobile 1H nuclear magnetic resonance (NMR) spectroscopy, in combination with solid phase extraction (SPE), to meet this metrology need. The NMR hardware employed featured a sufficiently homogeneous magnetic field, such that chemical shift differences could be used to unambiguously differentiate, and hence quantitatively detect, the required oil and solvent NMR signals. A solvent system consisting of 1% v/v chloroform in tetrachloroethylene was deployed, this provided a comparable 1H NMR signal intensity for the oil and the solvent (chloroform) and hence an internal reference 1H signal from the chloroform resulting in the measurement being effectively self-calibrating. The measurement process was applied to water contaminated with hexane or crude oil over the range 1-30 ppm. The results were validated against known solubility limits as well as infrared analysis and gas chromatography.

  3. Direct 13C NMR Detection in HPLC Hyphenation Mode

    DEFF Research Database (Denmark)

    Wubshet, Sileshi Gizachew; Johansen, Kenneth; Nyberg, Nils

    2012-01-01

    is indubitable in simplifying structural elucidations. In the current study, we demonstrated direct (13)C NMR detection of triterpenoids from a Ganoderma lucidum extract in hyphenation mode. The combined advantage of a cryogenically cooled probe, miniaturization, and multiple trapping enabled the first reported...

  4. Evaluation of algorithms for analysis of NMR relaxation decay curves

    NARCIS (Netherlands)

    Weerd, van der L.; Vergeldt, F.J.; Jager, de P.A.; As, van H.

    2000-01-01

    Quantitative processing of NMR relaxation images depends on the characteristics of the used fitting algorithm. Therefore several common fitting algorithms are compared for decay curves with low signal-to-noise ratios. The use of magnitude data yields a non-zero base line, and is shown to result in

  5. Solid State NMR Characterization and Adsorption Properties of ...

    African Journals Online (AJOL)

    ... agents and clinoptilolite at 140 °C inDMFunder nitrogen atmosphere. The light in weight and fluffy composites obtained were characterized by FT-IR, XRD, TGA, SEM and Solid State NMR. Results depicted possible chemical interactions between the two materials (lignocellulose and clinoptilolite). Used as adsorbents, the ...

  6. NMR investigation of boron impurities in refined metallurgical grade silicon

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, Hans-Joachim; Loeser, Wolfgang; Schmitz, Steffen; Sakaliyska, Miroslava [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Wurmehl, Sabine [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Institute for Solid State Physics, Technische Universitaet Dresden (Germany); Eisert, Stefan; Reichenbach, Birk; Mueller, Tim [Adensis GmbH, Dresden (Germany); Acker, Joerg; Rietig, Anja; Ducke, Jana [Department of Chemistry, Faculty for Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg (Germany)

    2015-09-15

    The nuclear magnetic resonance (NMR) method was applied for tracking boron impurities in the refining process of metallurgical grade (MG) silicon. From the NMR signal of the {sup 11}B isotope at an operating temperature 4.2 K, the boron concentration can be estimated down to the order of 1-10 wppm B. After melting and resolidification of MG-Si alloyed with Ca and Ti, a major fraction of B impurities remains in the Si solid solution as inferred from the characteristic NMR frequency. The alloying element Ti does not form substantial fractions of TiB{sub 2}. Acid leaching of crushed powders of MG-Si alloyed with Ca and Ti can diminish the initial impurity content of B suggesting its accumulation in the grain boundary phases. NMR signals of TiB{sub 2} at 4.2 K and room temperature (RT), and of poly-Si with different B doping at 4.2 K. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Numerical simulation of NQR/NMR: Applications in quantum computing.

    Science.gov (United States)

    Possa, Denimar; Gaudio, Anderson C; Freitas, Jair C C

    2011-04-01

    A numerical simulation program able to simulate nuclear quadrupole resonance (NQR) as well as nuclear magnetic resonance (NMR) experiments is presented, written using the Mathematica package, aiming especially applications in quantum computing. The program makes use of the interaction picture to compute the effect of the relevant nuclear spin interactions, without any assumption about the relative size of each interaction. This makes the program flexible and versatile, being useful in a wide range of experimental situations, going from NQR (at zero or under small applied magnetic field) to high-field NMR experiments. Some conditions specifically required for quantum computing applications are implemented in the program, such as the possibility of use of elliptically polarized radiofrequency and the inclusion of first- and second-order terms in the average Hamiltonian expansion. A number of examples dealing with simple NQR and quadrupole-perturbed NMR experiments are presented, along with the proposal of experiments to create quantum pseudopure states and logic gates using NQR. The program and the various application examples are freely available through the link http://www.profanderson.net/files/nmr_nqr.php. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. NMR-based screening of membrane protein ligands

    NARCIS (Netherlands)

    Yanamala, Naveena; Dutta, Arpana; Beck, Barbara; Van Fleet, Bart; Hay, Kelly; Yazbak, Ahmad; Ishima, Rieko; Doemling, Alexander; Klein-Seetharaman, Judith

    2010-01-01

    Membrane proteins pose problems for the application of NMR-based ligand-screening methods because of the need to maintain the proteins in a membrane mimetic environment such as detergent micelles: they add to the molecular weight of the protein, increase the viscosity of the solution, interact with

  9. SYNTHESIS, IR AND NMR SPECTRAL CORRELATIONS IN SOME ...

    African Journals Online (AJOL)

    Preferred Customer

    correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral data has been studied. KEY WORDS: Diimines, IR and NMR spectra, Spectral correlation, Hammett sigma constants.

  10. HIGH FIELD 13C NMR SPECTROSCOPIC ANALYSIS OF THE ...

    African Journals Online (AJOL)

    a

    2 carbon atoms of Sat in the β and α glyceridic positions. The. 34.114 ppm ... Table 1. 13C NMR chemical shifts of Jatropha curcas oil. Chemical shift (ppm). Assignment. 173.388. C-1, Sat. 173.302. C-1, O, L (α). 172.887. C-1, O, L (β). 34.223.

  11. Quantification of food polysaccharide mixtures by ¹H NMR

    NARCIS (Netherlands)

    Merkx, Donny W.H.; Westphal, Yvonne; Velzen, van Ewoud J.J.; Thakoer, Kavish V.; Roo, de Niels; Duynhoven, van John P.M.

    2018-01-01

    Polysaccharides are food ingredients that critically determine rheological properties and shelf life. A qualitative and quantitative assessment on food-specific polysaccharide mixtures by 1H NMR is presented. The method is based on the identification of intact polysaccharides, combined

  12. Extraction of alkaloids for NMR-based profiling

    DEFF Research Database (Denmark)

    Yilmaz, Ali; Nyberg, Nils; Jaroszewski, Jerzy W.

    2012-01-01

    A museum collection of Cinchona cortex samples (n = 117), from the period 1850–1950, were extracted with a mixture of chloroform-d1, methanol-d4, water-d2, and perchloric acid in the ratios 5:5:1:1. The extracts were directly analyzed using 1H NMR spectroscopy (600 MHz) and the spectra evaluated ...

  13. Advances in 27Al MAS NMR studies of geopolymers

    Czech Academy of Sciences Publication Activity Database

    Brus, Jiří; Abbrent, Sabina; Kobera, Libor; Urbanová, Martina; Cuba, P.

    2016-01-01

    Roč. 88, č. 2016 (2016), s. 79-147 ISSN 0066-4103 R&D Projects: GA ČR(CZ) GA13-24155S; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : geopolymers * aluminosilicates * solid-state NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.600, year: 2016

  14. Dynamics in photosynthetic transient complexes studied by paramagnetic NMR spectroscopy

    NARCIS (Netherlands)

    Scanu, Sandra

    2013-01-01

    This PhD thesis focuses on fundamental aspects of protein-protein interactions. A multidisciplinary methodology for the detection and visualization of transient, lowly-populated encounter protein complexes is described. The new methodology combined paramagnetic NMR spectroscopy with computational

  15. NMR metabolomics of thrips (Frankliniella occidentalis) resistance in Senecio hybrids.

    Science.gov (United States)

    Leiss, Kirsten A; Choi, Young H; Abdel-Farid, Ibrahim B; Verpoorte, Robert; Klinkhamer, Peter G L

    2009-02-01

    Western flower thrips (Frankliniella occidentalis) has become a key insect pest of agricultural and horticultural crops worldwide. Little is known about host plant resistance to thrips. In this study, we investigated thrips resistance in F (2) hybrids of Senecio jacobaea and Senecio aquaticus. We identified thrips-resistant hybrids applying three different bioassays. Subsequently, we compared the metabolomic profiles of these hybrids applying nuclear magnetic resonance spectroscopy (NMR). The new developments of NMR facilitate a wide range coverage of the metabolome. This makes NMR especially suitable if there is no a priori knowledge of the compounds related to herbivore resistance and allows a holistic approach analyzing different chemical compounds simultaneously. We show that the metabolomes of thrips-resistant and -susceptible hybrids differed considerably. Thrips-resistant hybrids contained higher amounts of the pyrrolizidine alkaloids (PA), jacobine, and jaconine, especially in younger leaves. Also, a flavanoid, kaempferol glucoside, accumulated in the resistant plants. Both PAs and kaempferol are known for their inhibitory effect on herbivores. In resistant and susceptible F (2) hybrids, young leaves showed less thrips damage than old leaves. Consistent with the optimal plant defense theory, young leaves contained increased levels of primary metabolites such as sucrose, raffinose, and stachyose, but also accumulated jacaranone as a secondary plant defense compound. Our results prove NMR as a promising tool to identify different metabolites involved in herbivore resistance. It constitutes a significant advance in the study of plant-insect relationships, providing key information on the implementation of herbivore resistance breeding strategies in plants.

  16. Synthesis, IR and NMR spectral correlations in some symmetrical ...

    African Journals Online (AJOL)

    A series of diimines have been synthesized by coupling of diamine with substituted benzaldehydes. The purities of these diimines were checked by their analytical and spectroscopic data. The spectral frequencies νCN (cm-1), NMR chemical shifts (δ, ppm) of C-H and C=N of these diimines have been correlated with ...

  17. Recent excitements in protein NMR: Large proteins and biologically ...

    Indian Academy of Sciences (India)

    The advent of Transverse Relaxation Optimized SpectroscopY (TROSY) and perdeuteration allowed biomolecularNMR spectroscopists to overcome the size limitation barrier (~20 kDa) in de novo structure determination of proteins.The utility of these techniques was immediately demonstrated on large proteins and protein ...

  18. Structural, vibrational, NMR, quantum chemical, DNA binding and ...

    Indian Academy of Sciences (India)

    Structural, vibrational, NMR, quantum chemical, DNA binding and protein docking studies of two flexible imine oximes. YUNUS KAYAa,b. aDepartment of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey. bDepartment of Chemistry, Faculty of Natural Sciences, Architecture, and Engineering, ...

  19. 235U NMR study of the itinerant antiferromagnet USb2

    International Nuclear Information System (INIS)

    Kato, Harukazu; Sakai, Hironori; Ikushima, Kenji; Kambe, Shinsaku; Tokunaga, Yo; Aoki, Dai; Haga, Yoshinori; O-bar nuki, Yoshichika; Yasuoka, Hiroshi; Walstedt, Russell E.

    2005-01-01

    We have succeeded in resolving a 235 U antiferromagnetic nuclear magnetic resonance (AFNMR) signal using 235 U-enriched samples of USb 2 . The uranium hyperfine field and coupling constant estimated for this compound are consistent with those from other experiments. This is the first reported observation of 235 U NMR in conducting host material

  20. Quantitative 1D saturation profiles on chalk by NMR

    DEFF Research Database (Denmark)

    Olsen, Dan; Topp, Simon; Stensgaard, Anders

    1996-01-01

    Quantitative one-dimensional saturation profiles showing the distribution of water and oil in chalk core samples are calculated from NMR measurements utilizing a 1D CSI spectroscopy pulse sequence. Saturation profiles may be acquired under conditions of fluid flow through the sample. Results reveal...

  1. Two-dimensional NMR studies of allyl palladium complexes of ...

    Indian Academy of Sciences (India)

    Administrator

    h3-Allyl complexes are intermediates in organic synthetic reactions such as allylic alkylation and amination. There is growing interest in understanding the structures of chiral h3-allyl intermediates as this would help to unravel the mechanism of enantioselective C–C bond forming reactions. Two-dimensional NMR study is a.

  2. NMR in rotating magnetic fields: Magic angle field spinning

    Energy Technology Data Exchange (ETDEWEB)

    Sakellariou, D.; Meriles, C.; Martin, R.; Pines, A.

    2004-09-10

    Magic angle sample spinning has been one of the cornerstones in high-resolution solid state NMR. Spinning frequencies nowadays have increased by at least one order of magnitude over the ones used in the first experiments and the technique has gained tremendous popularity. It is currently a routine procedure in solid-state NMR, high-resolution liquid-state NMR and solid-state MRI. The technique enhances the spectral resolution by averaging away rank 2 anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. Andrew proposed that it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B0 field (B0-MAS) and this has been recently demonstrated using electromagnetic field rotation. Here we discuss on the possibilities to perform field rotation using alternative hardware, together with spectroscopic methods to recover isotropic resolution even in cases where the field is not rotating at the magic angle. Extension to higher magnetic fields would be beneficial in situations where the physical manipulation of the sample is inconvenient or impossible. Such situations occur often in materials or biomedical samples where ''ex-situ'' NMR spectroscopy and imaging analysis is needed.

  3. NMR - finding in a case of Morquio's syndrome with syncope

    International Nuclear Information System (INIS)

    Treig, T.; Huk, W.; Nusslein, B.

    1987-01-01

    Acute or chronic cervical myelopathies are well known neurological complications of mucopolysaccharidoses This paper deals with a case of a mild form of Morquio's disease which appeared with syncope. NMR-imaging of the cranio-spinal region demonstrated a high intensity echo in the medulla oblongata before and after spinal decompression

  4. NMR study of thermoresponsive block copolymer in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

    2016-01-01

    Roč. 217, č. 12 (2016), s. 1370-1375 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * NMR * NOESY Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

  5. nmr spectroscopic study and dft calculations of vibrational analyses ...

    African Journals Online (AJOL)

    Preferred Customer

    Furthermore, GIAO/DFT (Gauge Including Atomic Orbitals/Density. Functional Theory) approach is extensively used for the calculations of chemical shifts for various types of compounds [14-20]. During the last decade an important breakthrough in the calculation of NMR spin-spin coupling constants took place when the ...

  6. (Cicer arietinum L.) seeds during germination by NMR spectroscopy

    African Journals Online (AJOL)

    Experiments were conducted to characterize the changes in water status during imbibition by nuclear magnetic resonance (NMR) spectroscopy in chickpea seeds exposed to static magnetic fields of 100 mT for 1 h. Water uptake during seed germination showed three phases with rapid initial hydration phase I, followed by ...

  7. Contribution of proton NMR relaxation to the investigation of ...

    Indian Academy of Sciences (India)

    Centro de Fisica da Materia Condensada (UL), Av. Prof. Gama Pinto 2, 1699 Lisboa Cedex, Portugal. IST (UTL), Av. Rovisco Pais, 1049-001 Lisboa, Portugal. *Author for correspondence. Abstract. We present in this work a review concerning wide frequency range T1 proton NMR relaxation studies performed in compounds ...

  8. NMR and NQR study of the thermodynamically stable quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Shastri, Ananda [Iowa State Univ., Ames, IA (United States)

    1995-02-10

    27Al and 61,65Cu NMR measurements are reported for powder samples of stable AlCuFe and AlCuRu icosahedral quasicrystals and their crystalline approximants, and for a AlPdMn single grain quasicrystal. Furthermore, 27Al NQR spectra at 4.2 K have been observed in the AlCuFe and AlCuRu samples. From the quadrupole perturbed NMR spectra at different magnetic fields, and from the zero field NQR spectra, a wide distribution of local electric field gradient (EFG) tensor components and principal axis system orientations was found at the Al site. A model EFG calculation based on a 1/1 AlCuFe approximant was successful in explaining the observed NQR spectra. It is concluded that the average local gradient is largely determined by the p-electron wave function at the Al site, while the width of the distribution is due to the lattice contribution to the EFG. Comparison of 63Cu NMR with 27Al NMR shows that the EFG distribution at the two sites is similar, but that the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more s-type wave function of the conduction electrons.

  9. Identification of Spinel Iron Oxide Nanoparticles by 57Fe NMR

    Directory of Open Access Journals (Sweden)

    SangGap Lee

    2011-12-01

    Full Text Available We have synthesized and studied monodisperse iron oxide nanoparticles of smaller than 10 nm to identify between the two spinel phases, magnetite and maghemite. It is shown that 57Fe NMR spectroscopy is a promising tool for distinguishing between the two phases.

  10. Facing and Overcoming Sensitivity Challenges in Biomolecular NMR Spectroscopy

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, Jan Henrik; Boebinger, Gregory S.; Comment, Arnaud

    2015-01-01

    enhance the sensitivity of solid‐ and liquid‐state experiments. While substantial advances have been made in all these areas, numerous challenges remain in the quest of endowing NMR spectroscopy with the sensitivity that has characterized forms of spectroscopies based on electrical or optical measurements....... These challenges, and the ways by which scientists and engineers are striving to solve them, are also addressed....

  11. NMR evidence of a valinomycin-proton complex

    Czech Academy of Sciences Publication Activity Database

    Kříž, Jaroslav; Makrlík, E.; Vaňura, P.

    2006-01-01

    Roč. 81, č. 2 (2006), s. 104-108 ISSN 0006-3525 R&D Projects: GA AV ČR 1ET400500402 Keywords : valinomycin * ion carriers * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.480, year: 2006

  12. Nondestructive NMR technique for moisture determination in radioactive materials.

    Energy Technology Data Exchange (ETDEWEB)

    Aumeier, S.; Gerald, R.E. II; Growney, E.; Nunez, L.; Kaminski, M.

    1998-12-04

    This progress report focuses on experimental and computational studies used to evaluate nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) for detecting, quantifying, and monitoring hydrogen and other magnetically active nuclei ({sup 3}H, {sup 3}He, {sup 239}Pu, {sup 241}Pu) in Spent nuclear fuels and packaging materials. The detection of moisture by using a toroid cavity NMR imager has been demonstrated in SiO{sub 2} and UO{sub 2} systems. The total moisture was quantified by means of {sup 1}H NMR detection of H{sub 2}O with a sensitivity of 100 ppm. In addition, an MRI technique that was used to determine the moisture distribution also enabled investigators to discriminate between bulk and stationary water sorbed on the particles. This imaging feature is unavailable in any other nondestructive assay (NDA) technique. Following the initial success of this program, the NMR detector volume was scaled up from the original design by a factor of 2000. The capacity of this detector exceeds the size specified by DOE-STD-3013-96.

  13. NMR Probe for Electrons in Semiconductor Mesoscopic Structures

    Indian Academy of Sciences (India)

    2009-11-14

    Nov 14, 2009 ... Strongly correlated electron systems: Overview. Problem: How to detect the electronic state in nanoscale structures. Two examples where the usual methods don't work. Solution: We showed NMR techniques can be very useful in such circumstances. Outline ...

  14. NMR studies on DNA binding specificity of the lac repressor

    NARCIS (Netherlands)

    Kopke Salinas, Roberto

    2005-01-01

    The thesis describes NMR structures of two protein-DNA complexes. The first structure shows how the protein, the DNA binding domain of lac repressor, recognizes its natural DNA binding site, by adaptation and read out of the nucleotide sequence. The second one shows how the DNA binding specificity

  15. Diamond Deposition and Defect Chemistry Studied via Solid State NMR

    Science.gov (United States)

    1994-06-30

    of the CSA powder patterns are characterized for CF. , hydroxyapatite . 25 groups. Within a certain band of motional narrowing, CF2 and HnchroughNMR e...containedinan epoxy -sealedglas tube. Ilm2. Room tmperature high-speed (15 kHz) MAS "FNMRspetra This Io r ofintensityoffthe highfrequency shoukde featurewould of

  16. Pulsed zero field NMR of solids and liquid crystals

    International Nuclear Information System (INIS)

    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

  17. NMR: nuclear magnetic resonance imaging; IRM: imagerie par resonance magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Doyon, D

    2003-07-01

    NMR has become an indispensable technique in medical imaging. Thanks to its innocuity, many informations are revealed by this technique in particular in the study of the cardiovascular system, of the pelvis, liver, breast of children and pregnant women. Thanks to its permanent improvements, NMR allows today a morphological but also a functional analysis of new domains, like the cerebral functions, the spectroscopy, the study of cerebral-spinal liquid fluxes, the diffusion and perfusion in tissues. The aim of this book is double: first to give to the reader the indispensable physical, technical and semeiological bases for the understanding of NMR, and to make a status of the most recent advances of this examination technique. This 4. edition has been fully updated in order to integrate the most recent technical advances, in particular in the head and osteo-articular domains. After an historical and technical recall, the different domains of application are presented according to a didactical scheme: description of techniques and preparation of examinations, presentation of normal results and of main pathologies. The interventional and functional NMR are the object of a more specific development. The main protocols of exploration with respect to body part and to the pathology are developed at the end of the book. (J.S.)

  18. NMR spectroscopy of muscle proteins; Spektroskopia MRJ bialek miesniowych

    Energy Technology Data Exchange (ETDEWEB)

    Slosarek, G. [Inst. Fizyki, Univ. A. Mickiewicza, Poznan (Poland)

    1995-12-31

    Author reviews various experimental techniques used for study of the structure of muscle proteins. Difficulties of application of NMR are described. Studies of the influence of Ca{sup 2+} on flexibility of actin polymer are presented. 11 refs, 3 figs.

  19. Study of cultured fibroblasts in vivo using NMR

    Energy Technology Data Exchange (ETDEWEB)

    Karczmar, G.S.

    1984-01-01

    The goal of this thesis was to study the compartmentation of phosphorylated glycolytic intermediates in intact Chicken Embryo Fibroblasts (CEFs) using /sup 31/P NMR at 109 MHz. Because glycolysis is regulated differently in normal and virally transformed CEFs, NMR experiments were performed on both types of cells. A technique for maintaining functional cells at high densities in an NMR magnet is described. Signals were detected from cytoplasmic inorganic phosphate (P/sub i/), ATP, NAD, NADH, phosphorylcholine and phosphorylethanolamine. The effect of external glucose on cytoplasmic pools of phosphates was studied. However, experiments with /sup 32/P labelled P/sub i/ showed that as the concentration of glucose in the medium was increased, the amount of phosphate sequestered in the cells increased. They conclude that there is a pool of P/sub i/ which is not detected by high resolution of NMR and that the size of this pool increases as the rate of glycolysis increases. These effects were found only in cultured cells; the data for transformed and normal cells were similar. Longitudinal relaxation times of intracellular phosphates in normal, transformed, and primary CEFs were measured.

  20. FT-IR, NMR SPECTROSCOPIC and QUANTUM MECHANICAL ...

    African Journals Online (AJOL)

    FT-IR, NMR SPECTROSCOPIC and QUANTUM MECHANICAL. INVESTIGATIONS OF TWO FERROCENE DERIVATIVES. Özgür Alver1* and Cemal Parlak2. 1Department of Physics, Science Faculty, Anadolu University, Eskişehir, 26470, Turkey. 2Department of Physics, Science Faculty, Ege University, İzmir, 35100, ...

  1. Ordering in nematic liquid crystals from NMR cross-polarization ...

    Indian Academy of Sciences (India)

    Abstract. The measurement of dipolar couplings between nuclei is a convenient way of obtatining directly liquid crystalline ordering through NMR since the coupling is dependent on the average orientation of the dipolar vector in the magnetic field which also aligns the liquid crystal. However, measurement of the dipolar ...

  2. 103Rh NMR spectroscopy and its application to rhodium chemistry.

    Science.gov (United States)

    Ernsting, Jan Meine; Gaemers, Sander; Elsevier, Cornelis J

    2004-09-01

    Rhodium is used for a number of large processes that rely on homogeneous rhodium-catalyzed reactions, for instance rhodium-catalyzed hydroformylation of alkenes, carbonylation of methanol to acetic acid and hydrodesulfurization of thiophene derivatives (in crude oil). Many laboratory applications in organometallic chemistry and catalysis involve organorhodium chemistry and a wealth of rhodium coordination compounds is known. For these and other areas, 103Rh NMR spectroscopy appears to be a very useful analytical tool. In this review, most of the literature concerning 103Rh NMR spectroscopy published from 1989 up to and including 2003 has been covered. After an introduction to several experimental methods for the detection of the insensitive 103Rh nucleus, a discussion of factors affecting the transition metal chemical shift is given. Computational aspects and calculations of chemical shifts are also briefly addressed. Next, the application of 103Rh NMR in coordination and organometallic chemistry is elaborated in more detail by highlighting recent developments in measurement and interpretation of 103Rh NMR data, in relation to rhodium-assisted reactions and homogeneous catalysis. The dependence of the 103Rh chemical shift on the ligands at rhodium in the first coordination sphere, on the complex geometry, oxidation state, temperature, solvent and concentration is treated. Several classes of compounds and special cases such as chiral rhodium compounds are reviewed. Finally, a section on scalar coupling to rhodium is provided. 2004 John Wiley & Sons, Ltd.

  3. NMR studies concerning base-base interactions in oligonucleotides

    International Nuclear Information System (INIS)

    Hoogen, Y.T. van den.

    1988-01-01

    Two main subjects are treated in the present thesis. The firsst part principally deals with the base-base interactions in single-stranded oligoribonucleotides. The second part presents NMR and model-building studies of DNA and RNA duplexes containing an unpaired base. (author). 242 refs.; 26 figs.; 24 tabs

  4. On the solid-state NMR spectra of naproxen

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří

    2015-01-01

    Roč. 619, 5 January (2015), s. 230-235 ISSN 0009-2614 R&D Projects: GA ČR(CZ) GA14-03636S Institutional support: RVO:61389013 Keywords : pharmaceutical s * NMR crystallography Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.860, year: 2015

  5. Brain 31P NMR spectroscopy in the conscious rat

    NARCIS (Netherlands)

    Deutz, N. E.; Bovée, W. M.; Chamuleau, R. A.

    1986-01-01

    Using a home-built head-body holder (HBH) which enables in vivo 31P NMR spectroscopy measurements on conscious rats, no significant changes were observed in the cerebral relative concentrations of ATP, phosphocreatine, phosphomonoesters, inorganic phosphate and intracellular pH during pentobarbital

  6. Fourier transform and its application to 1D and 2D NMR

    International Nuclear Information System (INIS)

    Canet, D.

    1988-01-01

    In this review article, the following points are developed: Pulsed NMR and Fourier transform; Fourier transform and two-dimensional spectroscopy; Mathematical properties of Fourier transform; Fourier transform of a sine function- one dimensional NMR; Fourier transform of a product of sine functions - two-dimensional NMR; Data manipulations in the time domain; Numerical Fourier transform [fr

  7. Magic-Angle-Spinning Solid-State NMR of Membrane Proteins

    NARCIS (Netherlands)

    Baker, Lindsay A.; Folkers, Gert E.; Sinnige, Tessa; Houben, Klaartje; Kaplan, M.; van der Cruijsen, Elwin A W; Baldus, Marc

    2015-01-01

    Solid-state NMR spectroscopy (ssNMR) provides increasing possibilities to examine membrane proteins in different molecular settings, ranging from synthetic bilayers to whole cells. This flexibility often enables ssNMR experiments to be directly correlated with membrane protein function. In this

  8. 'In vivo' and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study

    International Nuclear Information System (INIS)

    Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R.

    1995-01-01

    This work has developed a study on transgenic plants using two different techniques of nuclear magnetic resonance, in vivo NMR and high resolution NMR. In order to understand the gene mutations and characterize the plants constituents, NMR spectral data were analysed and discussed, then the results were presented

  9. Unilateral NMR applied to the conservation of works of art.

    Science.gov (United States)

    Del Federico, Eleonora; Centeno, Silvia A; Kehlet, Cindie; Currier, Penelope; Stockman, Denise; Jerschow, Alexej

    2010-01-01

    In conventional NMR, samples from works of art in sizes above those considered acceptable in the field of art conservation would have to be removed to place them into the bore of large superconducting magnets. The portable permanent-magnet-based systems, by contrast, can be used in situ to study works of art, in a noninvasive manner. One of these portable NMR systems, NMR-MOUSE(R), measures the information contained in one pixel in an NMR image from a region of about 1 cm(2), which can be as thin as 2-3 microm. With such a high depth resolution, profiles through the structures of art objects can be measured to characterize the materials, the artists' techniques, and the deterioration processes. A novel application of the technique to study a deterioration process and to follow up a conservation treatment is presented in which micrometer-thick oil stains on paper are differentiated and characterized. In this example, the spin-spin relaxation T (2) of the stain is correlated to the iodine number and to the degree of cross-linking of the oil, parameters that are crucial in choosing an appropriate conservation treatment to remove them. It is also shown that the variation of T (2) over the course of treatments with organic solvents can be used to monitor the progress of the conservation interventions. It is expected that unilateral NMR in combination with multivariate data analysis will fill a gap within the set of high-spatial-resolution techniques currently available for the noninvasive analysis of materials in works of art, where procedures to study the inorganic components are currently far more developed than those suitable for the study of the organic components.

  10. A global analysis of NMR distance constraints from the PDB

    International Nuclear Information System (INIS)

    Vranken, Wim

    2007-01-01

    Information obtained from Nuclear Magnetic Resonance (NMR) experiments is encoded as a set of constraint lists when calculating three-dimensional structures for a protein. With the amount of constraint data from the world wide Protein Data Bank (wwPDB) that is now available, it is possible to do a global, large-scale analysis using only information from the constraints, without taking the coordinate information into account. This article describes such an analysis of distance constraints from NOE data based on a set of 1834 NMR PDB entries containing 1909 protein chains. In order to best represent the quality and extent of the data that is currently deposited at the wwPDB, only the original data as deposited by the authors was used, and no attempt was made to 'clean up' and further interpret this information. Because the constraint lists provide a single set of data, and not an ensemble of structural solutions, they are easier to analyse and provide a reduced form of structural information that is relevant for NMR analysis only. The online resource resulting from this analysis makes it possible to check, for example, how often a particular contact occurs when assigning NOESY spectra, or to find out whether a particular sequence fragment is likely to be difficult to assign. In this respect it formalises information that scientists with experience in spectrum analysis are aware of but cannot necessarily quantify. The analysis described here illustrates the importance of depositing constraints (and all other possible NMR derived information) along with the structure coordinates, as this type of information can greatly assist the NMR community

  11. NMR Spectroscopy of the Hydrated Layer of Composite Particles Based on Nanosized Al2O3 and Vitreous Humor

    Science.gov (United States)

    Turov, V. V.; Gerashchenko, I. I.; Markina, A. I.

    2013-11-01

    The hydrated layer of composite particles prepared using Al2O3 and cattle vitreous humor was investigated using NMR spectroscopy. It was found that water bound to Al2O3 nanoparticles was present in the form of clusters with different degrees of association and energies of interaction with the surface. Water bound to the surface of the Al2O3/vitreous humor composite became more uniform upon immobilization of vitreous humor components on the surface of the Al2O3. With this, the clusters of adsorbed water had characteristics that were close to those found in air and weakly polar CHCl3 media. Addition of polar CH3CN led to the formation of very small water clusters. PMR spectra of the surface of the Al2O3/vitreous humor composite in the presence of trifluoroacetic acid differentiated four types of hydrated structures that differed in the degree of water association.

  12. The 'Nuts and Bolts' of 13C NMR Spectroscopy at Elevated-Pressures and -Temperatures for Monitoring In Situ CO2 Conversion to Metal Carbonates

    Science.gov (United States)

    Moore, J. K.; Surface, J. A.; Skemer, P. A.; Conradi, M. S.; Hayes, S. E.

    2013-12-01

    characterization of multiple metastable mineral phases in pure forms and in mixtures. Notably, NMR spectroscopy is able to observe signals from amorphous materials, and mixtures of both crystalline and amorphous species can be analyzed. NMR results are verified through a combination of Raman spectroscopy and powder XRD (of crystalline species). Further, we have examined the effects on mineralization reactions of pH gradients in the sample--also monitored in situ by NMR--and these results will be presented. Reference: 'In Situ Measurement of Magnesium Carbonate Formation from CO2 Using Static High-Pressure and -Temperature 13C NMR' J. Andrew Surface, Philip Skemer, Sophia E. Hayes, and Mark S. Conradi, Environ. Sci. Technol. 2013, 47, 119-125. DOI: 10.1021/es301287n

  13. Two dimensional NMR studies of polysaccharides

    International Nuclear Information System (INIS)

    Byrd, R.A.; Egan, W.; Summers, M.F.

    1987-01-01

    Polysaccharides are very important components in the immune response system. Capsular polysaccharides and lipopolysaccharides occupy cell surface sites of bacteria, play key roles in recognition and some have been used to develop vaccines. Consequently, the ability to determine chemical structures of these systems is vital to an understanding of their immunogenic action. The authors have been utilizing recently developed two-dimensional homonuclear and heteronuclear correlation spectroscopy for unambiguous assignment and structure determination of a number of polysaccharides. In particular, the 1 H-detected heteronuclear correlation experiments are essential to the rapid and sensitive determination of these structures. Linkage sites are determined by independent polarization transfer experiments and multiple quantum correlation experiments. These methods permit the complete structure determination on very small amounts of the polysaccharides. They present the results of a number of structural determinations and discuss the limits of these experiments in terms of their applications to polysaccharides

  14. Solid state NMR method development and studies of biological and biomimetic nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yanyan [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    This thesis describes application and development of advanced solid-state nuclear magnetic resonance techniques for complex materials, in particular organic-inorganic nanocomposites and thermoelectric tellurides. The apatite-collagen interface, essential for understanding the biomineralization process in bone and engineering the interface for controlled bio-mimetic synthesis and optimized mechanical properties, is buried within the nanocomposite of bone. We used multinuclear solid-state NMR to study the composition and structure of the interface. Citrate has been identified as the main organic molecule strongly bound to the apatite surface with a density of 1/(2 nm)2, covering 1/6 of the total surface area in bovine bone. Citrate provides more carboxylate groups, one of the key functional groups found to affect apatite nucleation and growth, than all the non-collagenous proteins all together in bone; thus we propose that citrate stabilizes apatite crystals at a very small thickness of ~3 nm (4 unit cells) to increase bone fracture tolerance. The hypothesis has been confirmed in vitro by adding citrate in the bio-mimetic synthesis of polymerhydroxyapatite nanocomposites. The results have shown that the size of hydroxyapatite nanocrystals decreases as increasing citrate concentration. With citrate concentrations comparable to that in body fluids, similar-sized nanocrystals as in bone have been produced. Besides the dimensions of the apatite crystals, the composition of bone also affects its biofunctional and macroscopic mechanical properties; therefore, our team also extended its effort to enhance the inorganic portion in our bio-mimetic synthesis from originally 15 wt% to current 50 wt% compared to 65 wt% in bovine bone, by using Lysine-Leucine hydroxyapatite nucleating diblock co-polypeptide, which forms a gel at very low concentration. In this thesis, various advanced solid state NMR techniques have been employed to characterize nanocomposites

  15. The structural topology of wild-type phospholamban in oriented lipid bilayers using 15N solid-state NMR spectroscopy.

    Science.gov (United States)

    Abu-Baker, Shadi; Lu, Jun-Xia; Chu, Shidong; Shetty, Kiran K; Gor'kov, Peter L; Lorigan, Gary A

    2007-11-01

    For the first time, 15N solid-state NMR experiments were conducted on wild-type phospholamban (WT-PLB) embedded inside mechanically oriented phospholipid bilayers to investigate the topology of its cytoplasmic and transmembrane domains. 15N solid-state NMR spectra of site-specific 15N-labeled WT-PLB indicate that the transmembrane domain has a tilt angle of 13 degrees+/-6 degrees with respect to the POPC (1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine) bilayer normal and that the cytoplasmic domain of WT-PLB lies on the surface of the phospholipid bilayers. Comparable results were obtained from site-specific 15N-labeled WT-PLB embedded inside DOPC/DOPE (1,2-dioleoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) mechanically oriented phospholipids' bilayers. The new NMR data support a pinwheel geometry of WT-PLB, but disagree with a bellflower structure in micelles, and indicate that the orientation of the cytoplasmic domain of the WT-PLB is similar to that reported for the monomeric AFA-PLB mutant.

  16. Natural Abundance 43Ca NMR as a Tool for Exploring Calcium Biomineralization: Renal Stone Formation and Growth

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, Geoffrey M.; Kirkpatrick, Robert J.

    2011-12-07

    Renal stone diseases are a global health issue with little effective therapeutic recourse aside from surgery and shock-wave lithotripsy, primarily because the fundamental chemical mechanisms behind calcium biomineralization are poorly understood. In this work, we show that natural abundance 43Ca NMR at 21.1 T is an effective means to probe the molecular-level Ca2+ structure in oxalate-based kidney stones. We find that the 43Ca NMR resonance of an authentic oxalate-based kidney stone cannot be explained by a single pure phase of any common Ca2+-bearing stone mineral. Combined with XRD results, our findings suggest an altered calcium oxalate monohydrate-like Ca2+ coordination environment for some fraction of Ca2+ in our sample. The evidence is consistent with existing literature hypothesizing that nonoxalate organic material interacts directly with Ca2+ at stone surfaces and is the primary driver of renal stone aggregation and growth. Our findings show that 43Ca NMR spectroscopy may provide unique and crucial insight into the fundamental chemistry of kidney stone formation, growth, and the role organic molecules play in these processes.

  17. Application of NMR-based techniques in aquatic toxicology: brief examples.

    Science.gov (United States)

    Tjeerdema, Ronald S

    2008-01-01

    Nuclear magnetic resonance spectroscopy (NMR) has been employed over many years for the elucidation of chemical structures. However, in more recent years it has been used to characterize sublethal actions of pollutants in aquatic organisms. For instance, in vivo NMR involves live, intact organisms or cell cultures and the application of chemical stressors to reveal toxic mechanisms in real time. Alternatively, NMR-based metabolomics involves rapid cessation of metabolic activity following chemical exposure (via liquid N(2)) to provide an assessment of metabolic actions via more traditional NMR analysis. Two examples are briefly presented to exemplify the power of NMR for assessing toxic actions in marine and freshwater organisms.

  18. Flow-through lipid nanotube arrays for structure-function studies of membrane proteins by solid-state NMR spectroscopy.

    Science.gov (United States)

    Chekmenev, Eduard Y; Gor'kov, Peter L; Cross, Timothy A; Alaouie, Ali M; Smirnov, Alex I

    2006-10-15

    A novel method for studying membrane proteins in a native lipid bilayer environment by solid-state NMR spectroscopy is described and tested. Anodic aluminum oxide (AAO) substrates with flow-through 175 nm wide and 60-mum-long nanopores were employed to form macroscopically aligned peptide-containing lipid bilayers that are fluid and highly hydrated. We demonstrate that the surfaces of both leaflets of such bilayers are fully accessible to aqueous solutes. Thus, high hydration levels as well as pH and desirable ion and/or drug concentrations could be easily maintained and modified as desired in a series of experiments with the same sample. The method allows for membrane protein NMR experiments in a broad pH range that could be extended to as low as 1 and as high as 12 units for a period of up to a few hours and temperatures as high as 70 degrees C without losing the lipid alignment or bilayers from the nanopores. We demonstrate the utility of this method by a solid-state 19.6 T (17)O NMR study of reversible binding effects of mono- and divalent ions on the chemical shift properties of the Leu(10) carbonyl oxygen of transmembrane pore-forming peptide gramicidin A (gA). We further compare the (17)O shifts induced by binding metal ions to the binding of protons in the pH range from 1 to 12 and find a significant difference. This unexpected result points to a difference in mechanisms for ion and proton conduction by the gA pore. We believe that a large number of solid-state NMR-based studies, including structure-function, drug screening, proton exchange, pH, and other titration experiments, will benefit significantly from the method described here.

  19. Chiral Discrimination through1H NMR and Luminescence Spectroscopy: Dynamic Processes and Solid Strip for Chiral Recognition.

    Science.gov (United States)

    Gangopadhyay, Monalisa; Maity, Arunava; Dey, Ananta; Rajamohanan, P R; Ravindranathan, Sapna; Das, Amitava

    2017-12-22

    The appropriate choice of the host molecules with well-defined optical activity (S-H/R-H) helps in the differentiation between two secondary ammonium ion-derivative guest molecules with different optical activities (R-G/S-G) based on the fluorescence resonance energy transfer (FRET)-based luminescence responses. Crown ether-based host molecules with opposite chiral configurations (R-H, S-H) have been derived from 1,1'-bi-2-naphthol (BINOL) derivatives that have axially chiral biaryl centers. These chiral crown ethers form host-guest complexes (i.e., [2]pseudorotaxanes) with chiral secondary ammonium ion derivatives (R-G, S-G). NMR spectroscopic studies show that the complexes are in a dynamic equilibrium in solution. Results of the 1 H NMR and fluorescence spectroscopic studies indicate a head-on orientation of the host and guest in the [2]pseudorotaxanes. The difference in the efficiency in the FRET-based responses between anthracene and the BINOL derivatives allow efficient chiral discrimination of the guests. Isothermal titration calorimetry and NMR investigations reveal that inclusion complexes between hosts and guests of the same chirality (R-H⋅R-G, S-H⋅S-G) are more stable relative to those of opposite chirality (R-H⋅S-G, S-H⋅R-G). However, FRET-based energy-transfer efficiency is higher for R-H⋅S-G and S-H⋅R-G complexes. NMR spectroscopic studies show that the relative orientation of the guest in the host cavity is significantly different when the host binds a guest of the same or opposite chirality; furthermore, the latter is more favorable for FRET, thus enabling discrimination between enantiomers. Interestingly, chiral discrimination of guest ions could also be achieved by using silica surfaces modified with chiral host molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. High resolution solid-state NMR spectroscopy of the Yersinia pestis outer membrane protein Ail in lipid membranes

    International Nuclear Information System (INIS)

    Yao, Yong; Dutta, Samit Kumar; Park, Sang Ho; Rai, Ratan; Fujimoto, L. Miya; Bobkov, Andrey A.; Opella, Stanley J.; Marassi, Francesca M.

    2017-01-01

    The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail’s biological activity. Here, we demonstrate that high-resolution solid-state NMR spectra can be obtained from samples of Ail in detergent-free phospholipid liposomes, prepared with a lipid to protein molar ratio of 100. The spectra, obtained with 13 C or 1 H detection, have very narrow line widths (0.40–0.60 ppm for 13 C, 0.11–0.15 ppm for 1 H, and 0.46–0.64 ppm for 15 N) that are consistent with a high level of sample homogeneity. The spectra enable resonance assignments to be obtained for N, CO, CA and CB atomic sites from 75 out of 156 residues in the sequence of Ail, including 80% of the transmembrane region. The 1 H-detected solid-state NMR 1 H/ 15 N correlation spectra obtained for Ail in liposomes compare very favorably with the solution NMR 1 H/ 15 N TROSY spectra obtained for Ail in nanodiscs prepared with a similar lipid to protein molar ratio. These results set the stage for studies of the molecular basis of the functional interactions of Ail with its protein partners from human host cells, as well as the development of drugs targeting Ail.