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Sample records for c-13 cpmg nmr

  1. Histidine side-chain dynamics and protonation monitored by C-13 CPMG NMR relaxation dispersion

    DEFF Research Database (Denmark)

    Hass, M. A. S.; Yilmaz, A.; Christensen, Hans Erik Mølager;

    2009-01-01

    The use of C-13 NMR relaxation dispersion experiments to monitor micro-millisecond fluctuations in the protonation states of histidine residues in proteins is investigated. To illustrate the approach, measurements on three specifically C-13 labeled histidine residues in plastocyanin (PCu) from...... Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for C-13(epsilon 1) nuclei in the histidine imidazole rings of A.v. PCu. The chemical shift changes obtained from the CPMG dispersion data are in good agreement with those obtained from...... states or other kinds of conformational changes of histidine side chains or their environment. Advantages and shortcomings of using the C-13(epsilon 1) dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains...

  2. Optimization of CPMG sequences for NMR borehole measurements

    Directory of Open Access Journals (Sweden)

    M. Ronczka

    2012-07-01

    Full Text Available Nuklear Magnetic Resonance (NMR can provide key information such as porosity and permeability for hydrological characterization of geological material. Especially the NMR transverse relaxation time T2 is used to estimate permeability since it reflects a pore-size dependent relaxation process. The measurement sequence (CPMG usually used consists of several thousands of electromagnetic pulses to densely record the relaxation process. These pulses are equidistantly spaced by a time constant τ. In NMR borehole applications the use of CPMG sequences for measuring the transverse relaxation time T2 is limited due to requirements on energy consumption. It is state of the art to conduct at least two sequences with different echo spacings (τ for recording fast and slow relaxing processes that correspond to different pore-sizes. For the purpose to reduce the amount of energy used for conducting CPMG sequences and to obtain both, slow and fast, decaying components within one sequence we tested the usage of CPMG sequences with an increasing τ and a decreasing number of pulses. A synthetic study as well as laboratory measurements on samples of glass beads and granulate of different grain size spectra were conducted to evaluate the effects of of an increasing τ spacing, e.g. an enhanced relaxation due to diffusion processes. The results are showing broadened T2 distributions if the number of pulses is decreasing and the mean grain size is increasing, which is mostly an effect of a significantly shortened acquisition time. The shift of T2 distributions to small decay times in dependence of the τ spacing and the mean grain size distribution is observable. We found that it is possible to conduct CPMG sequences with an increased τ spacing. According to the acquisition time and enhanced diffusion the sequence parameters (number of pulses and τmax has to be chosen carefully. Otherwise the underestimated relaxation time (T2 will lead to misinterpretations.

  3. GUARDD: user-friendly MATLAB software for rigorous analysis of CPMG RD NMR data

    OpenAIRE

    Kleckner, Ian R.; Foster, Mark P.

    2011-01-01

    Molecular dynamics are essential for life, and nuclear magnetic resonance (NMR) spectroscopy has been used extensively to characterize these phenomena since the 1950s. For the past 15 years, the Carr-Purcell Meiboom-Gill relaxation dispersion (CPMG RD) NMR experiment has afforded advanced NMR labs access to kinetic, thermodynamic, and structural details of protein and RNA dynamics in the crucial µs-ms time window. However, analysis of RD data is challenging because datasets are often large an...

  4. Optimization of CPMG sequences to measure NMR transverse relaxation time T2 in borehole applications

    Directory of Open Access Journals (Sweden)

    M. Ronczka

    2012-11-01

    Full Text Available Nuclear Magnetic Resonance (NMR can provide key information such as porosity and permeability for hydrological characterization of geological material. In particular the NMR transverse relaxation time T2 is used to estimate permeability since it reflects a pore-size dependent relaxation process. The measurement sequence (CPMG usually consists of several thousands of electromagnetic pulses to densely record the relaxation process and to avoid relaxation processes that are due to diffusion. These pulses are equidistantly spaced by a time constant tE. In NMR borehole applications the use of CPMG sequences for measuring the transverse relaxation time T2 is limited due to requirements on energy consumption. For measuring T2, it is state-of-the-art to conduct at least two sequences with different echo spacings (tE for recording fast and slow relaxing processes that correspond to different pore-sizes. We focus on conducting only a single CPMG sequence and reducing the amount of energy while obtaining both slow and fast decaying components and minimizing the influence of relaxation due to diffusion. Therefore, we tested the usage of CPMG sequences with an increasing tE and a decreasing number of pulses. A synthetic study as well as laboratory measurements on samples of glass beads and granulate material of different grain size spectra were conducted to evaluate the effects of an increasing tE. We show that T2 distributions are broadened if the number of pulses is decreasing and the mean grain size is increasing, which is mostly an effect of a significantly shortened acquisition time. The shift of T2 distributions to small decay times as a function of tE and the mean grain size distribution is observed. We found that it is possible to conduct CPMG sequences with an increased tE. According to the acquisition time and increasing influence of relaxation due to diffusion, the sequence parameters need to be chosen carefully to avoid misinterpretations.

  5. GUARDD: user-friendly MATLAB software for rigorous analysis of CPMG RD NMR data

    International Nuclear Information System (INIS)

    Molecular dynamics are essential for life, and nuclear magnetic resonance (NMR) spectroscopy has been used extensively to characterize these phenomena since the 1950s. For the past 15 years, the Carr-Purcell Meiboom-Gill relaxation dispersion (CPMG RD) NMR experiment has afforded advanced NMR labs access to kinetic, thermodynamic, and structural details of protein and RNA dynamics in the crucial μs-ms time window. However, analysis of RD data is challenging because datasets are often large and require many non-linear fitting parameters, thereby confounding assessment of accuracy. Moreover, novice CPMG experimentalists face an additional barrier because current software options lack an intuitive user interface and extensive documentation. Hence, we present the open-source software package GUARDD (Graphical User-friendly Analysis of Relaxation Dispersion Data), which is designed to organize, automate, and enhance the analytical procedures which operate on CPMG RD data (http://code.google.com/p/guardd/http://code.google.com/p/guardd/). This MATLAB-based program includes a graphical user interface, permits global fitting to multi-field, multi-temperature, multi-coherence data, and implements χ2-mapping procedures, via grid-search and Monte Carlo methods, to enhance and assess fitting accuracy. The presentation features allow users to seamlessly traverse the large amount of results, and the RD Simulator feature can help design future experiments as well as serve as a teaching tool for those unfamiliar with RD phenomena. Based on these innovative features, we expect that GUARDD will fill a well-defined gap in service of the RD NMR community.

  6. GUARDD: user-friendly MATLAB software for rigorous analysis of CPMG RD NMR data

    Energy Technology Data Exchange (ETDEWEB)

    Kleckner, Ian R., E-mail: ian.kleckner@gmail.com [Biophysics Program, Ohio State University (United States); Foster, Mark P., E-mail: Foster.281@osu.edu [Ohio State University, Biochemistry Department (United States)

    2012-01-15

    Molecular dynamics are essential for life, and nuclear magnetic resonance (NMR) spectroscopy has been used extensively to characterize these phenomena since the 1950s. For the past 15 years, the Carr-Purcell Meiboom-Gill relaxation dispersion (CPMG RD) NMR experiment has afforded advanced NMR labs access to kinetic, thermodynamic, and structural details of protein and RNA dynamics in the crucial {mu}s-ms time window. However, analysis of RD data is challenging because datasets are often large and require many non-linear fitting parameters, thereby confounding assessment of accuracy. Moreover, novice CPMG experimentalists face an additional barrier because current software options lack an intuitive user interface and extensive documentation. Hence, we present the open-source software package GUARDD (Graphical User-friendly Analysis of Relaxation Dispersion Data), which is designed to organize, automate, and enhance the analytical procedures which operate on CPMG RD data (http://code.google.com/p/guardd/http://code.google.com/p/guardd/). This MATLAB-based program includes a graphical user interface, permits global fitting to multi-field, multi-temperature, multi-coherence data, and implements {chi}{sup 2}-mapping procedures, via grid-search and Monte Carlo methods, to enhance and assess fitting accuracy. The presentation features allow users to seamlessly traverse the large amount of results, and the RD Simulator feature can help design future experiments as well as serve as a teaching tool for those unfamiliar with RD phenomena. Based on these innovative features, we expect that GUARDD will fill a well-defined gap in service of the RD NMR community.

  7. Histidine side-chain dynamics and protonation monitored by 13C CPMG NMR relaxation dispersion

    International Nuclear Information System (INIS)

    The use of 13C NMR relaxation dispersion experiments to monitor micro-millisecond fluctuations in the protonation states of histidine residues in proteins is investigated. To illustrate the approach, measurements on three specifically 13C labeled histidine residues in plastocyanin (PCu) from Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for 13Cε1 nuclei in the histidine imidazole rings of A.v. PCu. The chemical shift changes obtained from the CPMG dispersion data are in good agreement with those obtained from the chemical shift titration experiments, and the CPMG derived exchange rates agree with those obtained previously from 15N backbone relaxation measurements. Compared to measurements of backbone nuclei, 13Cε1 dispersion provides a more direct method to monitor interchanging protonation states or other kinds of conformational changes of histidine side chains or their environment. Advantages and shortcomings of using the 13Cε1 dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains are discussed

  8. Histidine side-chain dynamics and protonation monitored by {sup 13}C CPMG NMR relaxation dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Hass, Mathias A. S. [Leiden University, Institute of Chemistry (Netherlands); Yilmaz, Ali [University of Copenhagen, Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences (Denmark); Christensen, Hans E. M. [Technical University of Denmark, Department of Chemistry (Denmark); Led, Jens J. [University of Copenhagen, Department of Chemistry (Denmark)], E-mail: led@kiku.dk

    2009-08-15

    The use of {sup 13}C NMR relaxation dispersion experiments to monitor micro-millisecond fluctuations in the protonation states of histidine residues in proteins is investigated. To illustrate the approach, measurements on three specifically {sup 13}C labeled histidine residues in plastocyanin (PCu) from Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for {sup 13}C{sup {epsilon}}{sup 1} nuclei in the histidine imidazole rings of A.v. PCu. The chemical shift changes obtained from the CPMG dispersion data are in good agreement with those obtained from the chemical shift titration experiments, and the CPMG derived exchange rates agree with those obtained previously from {sup 15}N backbone relaxation measurements. Compared to measurements of backbone nuclei, {sup 13}C{sup {epsilon}}{sup 1} dispersion provides a more direct method to monitor interchanging protonation states or other kinds of conformational changes of histidine side chains or their environment. Advantages and shortcomings of using the {sup 13}C{sup {epsilon}}{sup 1} dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains are discussed.

  9. Application of 119Sn CPMG MAS NMR for Fast Characterization of Sn Sites in Zeolites with Natural 119Sn Isotope Abundance

    DEFF Research Database (Denmark)

    G. Kolyagin, Yury; V. Yakimo, Alexander; Tolborg, Søren;

    2016-01-01

    119Sn CPMG MAS NMR is demonstrated to be a fast and efficient method for characterization of Sn-sites in Sn-containing zeolites. Tuning of the CPMG echo-train sequence decreases the experimental time by a factor of 5–40 in the case of as-synthesized and hydrated Sn-BEA samples and by 3 orders of...

  10. C-13 NMR spectra of natural products part 5 - naphthopyrandiones and naphthofurandiones

    International Nuclear Information System (INIS)

    The synthesis of biologically active naphthoquinones using C-13 NMR is studied. The chemical procedure and aspect of carbon chemical shift used to distinguish between ortho and para quinones is described. (M.J.C.)

  11. Application of (119)Sn CPMG MAS NMR for Fast Characterization of Sn Sites in Zeolites with Natural (119)Sn Isotope Abundance.

    Science.gov (United States)

    Kolyagin, Yury G; Yakimov, Alexander V; Tolborg, Søren; Vennestrøm, Peter N R; Ivanova, Irina I

    2016-04-01

    (119)Sn CPMG MAS NMR is demonstrated to be a fast and efficient method for characterization of Sn-sites in Sn-containing zeolites. Tuning of the CPMG echo-train sequence decreases the experimental time by a factor of 5-40 in the case of as-synthesized and hydrated Sn-BEA samples and by 3 orders of magnitude in the case of dehydrated Sn-BEA samples as compared to conventional methods. In the latter case, the reconstruction of the quantitative spectrum without the loss of sensitivity is shown to be possible. The method proposed allows obtaining (119)Sn MAS NMR spectra with improved resolution for Sn-BEA zeolites with natural (119)Sn isotope abundance using conventional MAS NMR equipment. PMID:26978430

  12. C-13 NMR characterization of humic materials isolated by an MIBK partitioning procedure

    International Nuclear Information System (INIS)

    The organic matter from a peat and a stream sediment was fractionated into fulvic acid, humic acid, and humin using a previously reported MIBK (methylisobutyl ketone) partitioning procedure. The bulk stream sediment was collected from the north fork of Clear Creek, Gilpin County, Colorado. The north fork of Clear Creek has its headwaters in the bogs located on Guanella Pass, Gilpin County, Colorado. The peat sample was collected from a boggy soil, classified as a Cryohemist, on Guanella Pass. This work presents the solution state C-13 NMR spectra of humic materials isolated by a unique variation of the traditional method for extracting humus from a soil or peat and finds them typical of humic and fulvic acids. The C-13 NMR spectrum of the humin-humic acid, obtained by disaggregating humin through an extension of this method shows it to be very similar to the C-13 NMR spectrum of the corresponding humic acid recorded under identical conditions. (Auth.)

  13. Modification of the Varian XL-100 NMR spectrometer for submilligram natural abundance C-13 analyses

    Science.gov (United States)

    Wilson, D. M.; Olsen, R. W.; Burlingame, A. L.

    1974-01-01

    Quadrature detection modifications and a microcell arrangement are described for the Varian XL-100 NMR spectrometer which routinely improve sensitivity in C-13 Fourier transform sample-limited studies by a factor of 4 to 5. The power requirement of the RF pulse amplifier is relaxed by a factor of 4. Previously attainable resolution is not affected.

  14. H-1-, C-13-, and N-15-NMR chemical shifts for selected glucosides and ribosides of aromatic cytokinins

    Czech Academy of Sciences Publication Activity Database

    Vícha, J.; Maloň, Michal; Veselá, P.; Humpa, O.; Strnad, Miroslav; Marek, R.

    2010-01-01

    Roč. 48, č. 4 (2010), s. 318-322. ISSN 0749-1581 R&D Projects: GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : NMR * H-1 * C-13 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.247, year: 2010

  15. C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy; Application in patients with breast lesions

    Energy Technology Data Exchange (ETDEWEB)

    Fossell, E.T.; Hall, F.M. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Radiology); McDonagh, J. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Pathology)

    1991-05-01

    The authors have previously described the application of water-suppressed proton nuclear magnetic resonance (H-1 NMR) spectroscopy of plasma for detection of malignancy. Subsequently, hypertriglyceridemia has been identified as a source of false positive results. Here is described a confirmatory, adjunctive technique -analysis of the carbon-13 (C-13) NMR spectrum of plasma- which also identifies the presence of malignancy but is not sensitive to the plasma triglyceride level. Blinded plasma samples from 480 normal donors and 208 patients scheduled for breast biopsy were analyzed by water-suppressed H-1 and C-13 NMR spectroscopy. Triglyceride levels were also measured. Among the normal donors, there were 38 individuals with hypertriglyceridemia of whom 18 had results consistent with malignancy by H-1 NMR spectroscopy. However, the C-13 technique reduced the apparent H-1 false positive rate from 7.0 to 0.6 percent. Similarly, in the breast biopsy cohort, C-13 reduced the false positive rate from 2.8 to 0.9 percent. Furthermore, the accuracy of the combined H-1/C-13 test in this blinded study was greater than 96 percent in 208 patients studied. (author). 27 refs.; 5 figs.; 4 tabs.

  16. Absolute nutrient concentration measurements in cell culture media: (1)H q-NMR spectra and data to compare the efficiency of pH-controlled protein precipitation versus CPMG or post-processing filtering approaches.

    Science.gov (United States)

    Goldoni, Luca; Beringhelli, Tiziana; Rocchia, Walter; Realini, Natalia; Piomelli, Daniele

    2016-09-01

    The NMR spectra and data reported in this article refer to the research article titled "A simple and accurate protocol for absolute polar metabolite quantification in cell cultures using q-NMR" [1]. We provide the (1)H q-NMR spectra of cell culture media (DMEM) after removal of serum proteins, which show the different efficiency of various precipitating solvents, the solvent/DMEM ratios, and pH of the solution. We compare the data of the absolute nutrient concentrations, measured by PULCON external standard method, before and after precipitation of serum proteins and those obtained using CPMG (Carr-Purcell-Meiboom-Gill) sequence or applying post-processing filtering algorithms to remove, from the (1)H q-NMR spectra, the proteins signal contribution. For each of these approaches, the percent error in the absolute value of every measurement for all the nutrients is also plotted as accuracy assessment. PMID:27331118

  17. Solid State C-13 and H-2 NMR Investigations of Paramagnetic Ni(II)(acac)(2)L-2 Complexes

    DEFF Research Database (Denmark)

    Lennartson, A.; Christensen, Lene Ulrikke; McKenzie, C. J.;

    2014-01-01

    = hexafluoroacetylonato, have been characterized by solid state C-13 MAS NMR spectroscopy. H-2 MAS NMR was used to probe the local hydrogen bonding network in [Ni(acac)(2)(D2O)(2)]D2O and cis-[Ni(F-6-acac)(2)(D2O)(2)]. The complexes serve to benchmark the paramagnetic shift, which can be associated with the resonances of......[Ni(acac)(2)(PMe2Ph)(2)], trans-[Ni(acac)(2)(PMePh2)(2)], and the noncrystallographically characterized trans-[Ni(acac)(2)(dppe)], were assigned using these correlations. The complexes with L = H2O, D2O, NH3, and MeOH can be prepared by a series of solid state desorption and sorption reactions. Crystal...... atoms of the coordinated ligands. The methine (CH) and methyl (CH3) have characteristic combinations of the isotropic shift (delta) and anisotropy parameters (d, eta). The size of the anisotropy (d), which is the sum of the chemical shift anisotropy (CSA) and the paramagnetic electron-nuclei dipolar...

  18. Field gradient CPMG applied on postmortem muscles.

    Science.gov (United States)

    Bertram, Hanne Christine

    2004-05-01

    As a new approach, Carr-Purcell-Meiboom-Gill (CPMG) experiments were performed in vitro on porcine muscles (n = 10) during the period from 15 min to 85 min postmortem and again at 24 h postmortem in the absence (G = 0) and the presence of an external field gradient (G = 0.5*10(-3) T/m), which was applied throughout the CPMG sequence. The experiments were performed on low-field nuclear magnetic resonance (NMR) equipment (0.47 T). Due to the inclusion of different pre-slaughter treatments (adrenaline treatment and pre-slaughter exercise/electrical stunning), the muscles could be divided into (I) a group (n = 5) characterized by a reduced decrease in pH postmortem and a high water-holding capacity and (II) a group (n = 5) characterized by an increased rate of pH decrease postmortem and a low water-holding capacity. Distributed analysis of the CPMG data revealed two major relaxation populations with relaxation times about 30-40 and 200-500 ms, respectively, and comparison of data obtained with G = 0 and G = 0.5*10(-3) T/m revealed effects of the external gradient on the relaxation time of both the two relaxation populations, which implies that both diffusion and relaxation contributes to the relaxation of the two populations. At 24 h postmortem the effect of the external field gradient on the relaxation time was significantly affected by muscle group (I vs. II), which reveals local differences in water diffusion in the two meat qualities. Finally, the discriminatory power with regard to muscle group (I vs. II) was investigated for data acquired with G = 0 and G = F = 0.5*10(-3) T/m, and both the two types of data were found highly suitable for separation of muscles according to meat quality. PMID:15120176

  19. Accurate measurements of 13C-13C distances in uniformly 13C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    International Nuclear Information System (INIS)

    Application of sets of 13C-13C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important 13C-13C distances in uniformly 13C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl (13C′) and aliphatic (13Caliphatic) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly 13C,15N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of 13C′-13Caliphatic distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform 13C,15N-labeling on the FGAIL fragment

  20. Fullerene C-70 characterization by C-13 NMR and the importance of the solvent and dynamics in spectral simulations

    Czech Academy of Sciences Publication Activity Database

    Kaminský, Jakub; Buděšínský, Miloš; Taubert, S.; Bouř, Petr; Straka, Michal

    2013-01-01

    Roč. 15, č. 23 (2013), s. 9223-9230. ISSN 1463-9076 R&D Projects: GA ČR GA13-03978S; GA ČR GPP208/10/P356; GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033; GA ČR GA203/09/2037 Grant ostatní: AV ČR(CZ) M200551205 Institutional support: RVO:61388963 Keywords : fullerene * NMR * simulations * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.198, year: 2013

  1. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    Science.gov (United States)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  2. The depletion of protein signals in metabonomics analysis with the WET-CPMG pulse sequence

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool capable of providing a comprehensive metabolic profile of biofluids such as urine, plasma, and serum. Unfortunately, when measuring serum and plasma, the high protein concentration can obscure the signals originating from low molecular weight metabolites. We evaluated the use of different parameters within the Carr-Purcell-Meiboom-Gill (CPMG) pulse train of fast spin-echoes to remove the macromolecular signal contribution in one-dimensional proton (1H) NMR spectra. Experimental parameters such as the refocusing delay in the CPMG pulse train, pulse miscalibration, and recycle time were examined to assess the ability to remove the protein signals from the spectrum without causing a deleterious effect on the signals originating from free, low molecular weight metabolites. The 1H-NMR spectra of a variety of serum samples spiked with 2'-deoxyadenosine were acquired using various acquisition parameters. Our results show that the delay used in the CPMG spin-echo and the combination of the acquisition pulse flip angle and recycle time are the two major factors affecting the observed metabolite signal amplitudes in the resulting 1H-NMR spectrum

  3. Application of binomial-edited CPMG to shale characterization

    Science.gov (United States)

    Washburn, Kathryn E.; Birdwell, Justin E.

    2014-01-01

    Unconventional shale resources may contain a significant amount of hydrogen in organic solids such as kerogen, but it is not possible to directly detect these solids with many NMR systems. Binomial-edited pulse sequences capitalize on magnetization transfer between solids, semi-solids, and liquids to provide an indirect method of detecting solid organic materials in shales. When the organic solids can be directly measured, binomial-editing helps distinguish between different phases. We applied a binomial-edited CPMG pulse sequence to a range of natural and experimentally-altered shale samples. The most substantial signal loss is seen in shales rich in organic solids while fluids associated with inorganic pores seem essentially unaffected. This suggests that binomial-editing is a potential method for determining fluid locations, solid organic content, and kerogen–bitumen discrimination.

  4. A Mo-95 and C-13 Solid-state NMR and Relativistic DFT Investigation of Mesitylenetricarbonylmolybdenum(0) -a Typical Transition Metal Piano-stool Complex

    Energy Technology Data Exchange (ETDEWEB)

    Bryce, David L.; Wasylishen, Roderick E.

    2002-06-21

    The chemical shift (CS) and electric field gradient (EFG) tensors in the piano-stool compound mesitylenetricarbonylmolybdenum(0), 1, have been investigated via {sup 95}Mo and {sup 13}C solid-state magic-angle spinning (MAS) NMR as well as relativistic zeroth-order regular approximation density functional theory (ZORA-DFT) calculations. Molybdenum-95 (I = 5/2) MAS NMR spectra acquired at 18.8 T are dominated by the anisotropic chemical shift interaction ({Omega} = 775 {+-} 30 ppm) rather than the 2nd-order quadrupolar interaction (C{sub Q} = -0.96 {+-} 0.15 MHz), an unusual situation for a quadrupolar nucleus. ZORA-DFT calculations of the {sup 95}Mo EFG and CS tensors are in agreement with the experimental data. Mixing of appropriate occupied and virtual d-orbital dominated MOs in the region of the HOMO-LUMO gap are shown to be responsible for the large chemical shift anisotropy. The small, but non-negligible, {sup 95}Mo quadrupolar interaction is discussed in terms of the geometry about Mo. Carbon-13 CPMAS spectra acquired at 4.7 T demonstrate the crystallographic and magnetic nonequivalence of the twelve {sup 13}C nuclei in 1, despite the chemical equivalence of some of these nuclei in isotropic solutions. The principal components of the carbon CS tensors are determined via a Herzfeld-Berger analysis, and indicate that motion of the mesitylene ring is slow compared to a rate which would influence the carbon CS tensors (i.e. tens of {micro}s). ZORA-DFT calculations reproduce the experimental carbon CS tensors accurately. Oxygen-17 EFG and CS tensors for 1 are also calculated and discussed in terms of existing experimental data for related molybdenum carbonyl compounds. This work provides an example of the information available from combined multi-field solid-state multinuclear magnetic resonance and computational investigations of transition metal compounds, in particular the direct study of quadrupolar transition metal nuclei with relatively small magnetic moments.

  5. Two dimensional IR-FID-CPMG acquisition and adaptation of a maximum entropy reconstruction

    Science.gov (United States)

    Rondeau-Mouro, C.; Kovrlija, R.; Van Steenberge, E.; Moussaoui, S.

    2016-04-01

    By acquiring the FID signal in two-dimensional TD-NMR spectroscopy, it is possible to characterize mixtures or complex samples composed of solid and liquid phases. We have developed a new sequence for this purpose, called IR-FID-CPMG, making it possible to correlate spin-lattice T1 and spin-spin T2 relaxation times, including both liquid and solid phases in samples. We demonstrate here the potential of a new algorithm for the 2D inverse Laplace transformation of IR-FID-CPMG data based on an adapted reconstruction of the maximum entropy method, combining the standard decreasing exponential decay function with an additional term drawn from Abragam's FID function. The results show that the proposed IR-FID-CPMG sequence and its related inversion model allow accurate characterization and quantification of both solid and liquid phases in multiphasic and compartmentalized systems. Moreover, it permits to distinguish between solid phases having different T1 relaxation times or to highlight cross-relaxation phenomena.

  6. Strong coupling effects during X-pulse CPMG experiments recorded on heteronuclear ABX spin systems: artifacts and a simple solution

    International Nuclear Information System (INIS)

    Simulation and experiment have been used to establish that significant artifacts can be generated in X-pulse CPMG relaxation dispersion experiments recorded on heteronuclear ABX spin-systems, such as 13Ci-13Cj-1H, where 13Ci and 13Cj are strongly coupled. A qualitative explanation of the origin of these artifacts is presented along with a simple method to significantly reduce them. An application to the measurement of 1H CPMG relaxation dispersion profiles in an HIV-2 TAR RNA molecule where all ribose sugars are protonated at the 2' position, deuterated at all other sugar positions and 13C labeled at all sugar carbons is presented to illustrate the problems that strong 13C-13C coupling introduces and a simple solution is proposed

  7. Enhanced accuracy of kinetic information from CT-CPMG experiments by transverse rotating-frame spectroscopy

    International Nuclear Information System (INIS)

    Micro-to-millisecond motions of proteins transmit pivotal signals for protein function. A powerful technique for the measurement of these motions is nuclear magnetic resonance spectroscopy. One of the most widely used methodologies for this purpose is the constant-time Carr–Purcell–Meiboom–Gill (CT-CPMG) relaxation dispersion experiment where kinetic and structural information can be obtained at atomic resolution. Extraction of accurate kinetics determined from CT-CPMG data requires refocusing frequencies that are much larger than the nuclei’s exchange rate between states. We investigated the effect when fast processes are probed by CT-CPMG experiments via simulation and show that if the intrinsic relaxation rate (R(CT-CPMG)(2,0) is not known a priori the extraction of accurate kinetics is hindered. Errors on the order of 50 % in the exchange rate are attained when processes become fast, but are minimized to 5 % with a priori R2,0CT-CPMG information. To alleviate this shortcoming, we developed an experimental scheme probing R2,0CT-CPMG with large amplitude spin-lock fields, which specifically contains the intrinsic proton longitudinal Eigenrelaxation rate. Our approach was validated with ubiquitin and the Oscillatoria agardhii agglutinin (OAA). For OAA, an underestimation of 66 % in the kinetic rates was observed if R2,0CT-CPMG is not included during the analysis of CT-CPMG data and result in incorrect kinetics and imprecise amplitude information. This was overcome by combining CT-CPMG with R2,0CT-CPMG measured with a high power R1ρ experiment. In addition, the measurement of R2,0CT-CPMG removes the ambiguities in choosing between different models that describe CT-CPMG data

  8. New guidelines for delta C-13 measurements

    NARCIS (Netherlands)

    Coplen, TB; Brand, WA; Gehre, M; Groning, M; Meijer, HAJ; Toman, B; Verkouteren, RM; Coplen, Tyler B.; Brand, Willi A.; Gröning, Manfred

    2006-01-01

    Consistency of delta C-13 measurements can be improved 39-47% by anchoring the delta C-13 scale with two isotopic reference materials differing substantially in C-13/C-12. It is recommended that delta C-13 values of both organic and inorganic materials be measured and expressed relative to VPDB (Vie

  9. CPMG relaxation rate dispersion in dipole fields around capillaries.

    Science.gov (United States)

    Kurz, F T; Kampf, T; Buschle, L R; Heiland, S; Schlemmer, H-P; Bendszus, M; Ziener, C H

    2016-09-01

    Transverse relaxation rates for Carr-Purcell-Meiboom-Gill (CPMG) sequences increase with inter-echo time in presence of microscopic magnetic field inhomogeneities due to nuclear spin diffusion. For a weak field approximation that includes diffusion effects, the CPMG relaxation rate shift for proton diffusion around capillaries in muscle tissue can be expressed in terms of a frequency correlation function and the inter-echo time. The present work provides an analytical expression for the local relaxation rate shift that is dependent on local blood volume fraction, diffusion coefficient, capillary radius, susceptibility difference and inter-echo time. Asymptotic regions of the model are in agreement with previous modeling results of Brooks et al., Luz et al. and Ziener et al. In comparison with simulation data, the model shows an equal or better accuracy than established approximations. Also, model behavior coincides with experimental data for rat heart and skeletal muscle. The present work provides analytical tools to extract sub-voxel information about uniform capillary networks that can be used to study capillary organization or micro-circulatory remodeling. PMID:27071310

  10. Proton-decoupled CPMG: A better experiment for measuring 15N R2 relaxation in disordered proteins

    Science.gov (United States)

    Yuwen, Tairan; Skrynnikov, Nikolai R.

    2014-04-01

    15N R2 relaxation is one of the most informative experiments for characterization of intrinsically disordered proteins (IDPs). Small changes in nitrogen R2 rates are often used to determine how IDPs respond to various biologically relevant perturbations such as point mutations, posttranslational modifications and weak ligand interactions. However collecting high-quality 15N relaxation data can be difficult. Of necessity, the samples of IDPs are often prepared with low protein concentration and the measurement time can be limited because of rapid sample degradation. Furthermore, due to hardware limitations standard experiments such as 15N spin-lock and CPMG can sample the relaxation decay only to ca. 150 ms. This is much shorter than 15N T2 times in disordered proteins at or near physiological temperature. As a result, the sampling of relaxation decay profiles in these experiments is suboptimal, which further lowers the precision of the measurements. Here we report a new implementation of the proton-decoupled (PD) CPMG experiment which allows one to sample 15N R2 relaxation decay up to ca. 0.5-1 s. The new experiment has been validated through comparison with the well-established spin-lock measurement. Using dilute samples of denatured ubiquitin, we have demonstrated that PD-CPMG produces up to 3-fold improvement in the precision of the data. It is expected that for intrinsically disordered proteins the gains may be even more substantial. We have also shown that this sequence has a number of favorable properties: (i) the spectra are recorded with narrow linewidth in nitrogen dimension; (ii) 15N offset correction is small and easy to calculate; (iii) the experiment is immune to various spurious effects arising from solvent exchange; (iv) the results are stable with respect to pulse miscalibration and rf field inhomogeneity; (v) with minimal change, the pulse sequence can also be used to measure R2 relaxation of 15Nε spins in arginine side chains. We anticipate that

  11. Substitution effect in nuclear magnetic resonance of C-13: α methoxicyclohexanones

    International Nuclear Information System (INIS)

    Eletronic and steric interactions between the carbonyl and methoxyl groups in α-methoxicyclohexanones by H-1 and C-13 nuclear magnetic resonance spectroscopy (n.m.r) is studied. Interpretation of H-1 n.m.r measurements based on the carbonyl group anisotropy is made. The asigment of spectral lines to specific nuclear by Lanthanide Shift Reagent Experiments is confirmed. Interpretation of C-13 n.m.r. spectra with respect to molecular effects and emphirical relationships associated with the substituent was analysed. The C-13 chemical shift asignment by comparison with results of partially (SFORD) and fully decompled spectra and also by relating the measured chemical shift with values cited in the literature for similar compounds are made. A qualitative study using I.R. spectroscopy in attempt to evaluate the predominance of one the conformers of the studied compounds in solutions of n-hexan and chloroform is made. (M.J.C.)

  12. Systematic Errors Associated with the CPMG Pulse Sequence and Their Effect on Motional Analysis of Biomolecules

    Science.gov (United States)

    Ross, A.; Czisch, M.; King, G. C.

    1997-02-01

    A theoretical approach to calculate the time evolution of magnetization during a CPMG pulse sequence of arbitrary parameter settings is developed and verified by experiment. The analysis reveals that off-resonance effects can cause systematic reductions in measured peak amplitudes that commonly lie in the range 5-25%, reaching 50% in unfavorable circumstances. These errors, which are finely dependent upon frequency offset and CPMG parameter settings, are subsequently transferred into erroneousT2values obtained by curve fitting, where they are reduced or amplified depending upon the magnitude of the relaxation time. Subsequent transfer to Lipari-Szabo model analysis can produce significant errors in derived motional parameters, with τeinternal correlation times being affected somewhat more thanS2order parameters. A hazard of this off-resonance phenomenon is its oscillatory nature, so that strongly affected and unaffected signals can be found at various frequencies within a CPMG spectrum. Methods for the reduction of the systematic error are discussed. Relaxation studies on biomolecules, especially at high field strengths, should take account of potential off-resonance contributions.

  13. Optimization of Brain T2 Mapping Using Standard CPMG Sequence In A Clinical Scanner

    Science.gov (United States)

    Hnilicová, P.; Bittšanský, M.; Dobrota, D.

    2014-04-01

    In magnetic resonance imaging, transverse relaxation time (T2) mapping is a useful quantitative tool enabling enhanced diagnostics of many brain pathologies. The aim of our study was to test the influence of different sequence parameters on calculated T2 values, including multi-slice measurements, slice position, interslice gap, echo spacing, and pulse duration. Measurements were performed using standard multi-slice multi-echo CPMG imaging sequence on a 1.5 Tesla routine whole body MR scanner. We used multiple phantoms with different agarose concentrations (0 % to 4 %) and verified the results on a healthy volunteer. It appeared that neither the pulse duration, the size of interslice gap nor the slice shift had any impact on the T2. The measurement accuracy was increased with shorter echo spacing. Standard multi-slice multi-echo CPMG protocol with the shortest echo spacing, also the smallest available interslice gap (100 % of slice thickness) and shorter pulse duration was found to be optimal and reliable for calculating T2 maps in the human brain.

  14. The C-12/C-13 Ratio as a Chemistry Indicator

    Science.gov (United States)

    Wirstroem, Eva; Geppert, Wolf; Persson, Carina; Charnley, Steven

    2011-01-01

    Isotopic ratios of elements are considered powerful tools, e.g. in tracing the origin of solar system body materials, or the degree of nucleosynthesis processing throughout the Galaxy. In interstellar molecules, some isotopic ratios like H/D and C-12/C-13 can also be used as indicators of their chemical origin. Isotope fractionation in gas-phase chemical reactions and gas-dust interaction makes observations of the ratio between C-12 and C-13 isotopologues suitable to distinguish between different formation scenarios. We will present observations of the C-12/C-13 ratio in methanol and formaldehyde towards a sample of embedded, massive young stellar objects. In relation to this we also present results from theoretical modeling showing the usefulness of the C-12/C-13 ratio as a chemistry indicator.

  15. Metabolic Signatures of Lung Cancer in Biofluids: NMR-Based Metabonomics of Blood Plasma

    OpenAIRE

    Rocha, Cláudia M.; Carrola, Joana; Barros, António S.; Gil, Ana M; Goodfellow, Brian J; Carreira, Isabel M; Bernardo, Joao; Gomes, Ana; Sousa, Vitor; Carvalho, Lina; Duarte, Iola F.

    2011-01-01

    In this work, the variations in the metabolic profile of blood plasma from lung cancer patients and healthy controls were investigated through NMR-based metabonomics, to assess the potential of this approach for lung cancer screening and diagnosis. PLS-DA modeling of CPMG spectra from plasma, subjected to Monte Carlo Cross Validation, allowed cancer patients to be discriminated from controls with sensitivity and specificity levels of about 90%. Relatively lower HDL and higher VLDL + LDL in th...

  16. Probing Microsecond Time Scale Dynamics in Proteins by Methyl H-1 Carr-Purcell-Meiboom-Gill Relaxation Dispersion NMR Measurements. Application to Activation of the Signaling Protein NtrC(r)

    NARCIS (Netherlands)

    Otten, Renee; Villali, Janice; Kern, Dorothee; Mulder, Frans A. A.

    2010-01-01

    To study microsecond processes by relaxation dispersion NMR spectroscopy, low power deposition and short pulses are crucial and encourage the development of experiments that employ H-1 Carr-Purcell-Meiboom-Gill (CPMG) pulse trains. Herein, a method is described for the comprehensive study of microse

  17. Study of the fusion reaction 13C+13C

    International Nuclear Information System (INIS)

    The fusion reaction 13C+13C has been studied, it must allow, by comparisons with the system 12C+13C already studied to determine how the presence of a supplementary nucleon in the interaction nuclei of the entrance channel affects the energy dependence of the reaction cross section. The reaction 13C+13C has been studied for incident energies E(CM)=3.05 - 6.88 MeV and no resonant structure seems to appear in the coulombian energies. The reaction products are identified by the energy of their gamma transition using a germanium detector situated at zero degree with respect to the incident beam at approximately 1 cm from the target

  18. Multi-platform subsystem for controlling acquisition, visualization and data organization of an NMR Digital Spectrometer: ToRM Console

    International Nuclear Information System (INIS)

    In this work, we present the recent results from the development of the CIERMag NMR Digital Spectrometer - a subsystem for controlling acquisition, visualization and data organization. Some aspects of the architecture and features will be shown, including a demonstration with CPMG method for transversal relaxation time (T2) measurement using the system. With these achievements, ToRM Console is now being prepared to be an MRI scanner in a near future (author)

  19. Relationships between 1H NMR Relaxation Data and Some Technological Parameters of Meat: A Chemometric Approach

    Science.gov (United States)

    Brown, Robert J. S.; Capozzi, Francesco; Cavani, Claudio; Cremonini, Mauro A.; Petracci, Massimiliano; Placucci, Giuseppe

    2000-11-01

    In this paper chemometrics (ANOVA and PCR) is used to measure unbiased correlations between NMR spin-echo decays of pork M. Longissimus dorsi obtained through Carr-Purcell-Meiboom-Gill (CPMG) experiments at low frequency (20 MHz) and the values of 14 technological parameters commonly used to assess pork meat quality. On the basis of the ANOVA results, it is also found that the CPMG decays of meat cannot be best interpreted with a "discrete" model (i.e., by expanding the decays in a series of a discrete number of exponential components, each with a different transverse relaxation time), but rather with a "continuous" model, by which a continuous distribution of T2's is allowed. The latter model also agrees with literature histological results.

  20. A C13-norisoprenoid gentiobioside from quince fruit.

    Science.gov (United States)

    Winterhalter, P; Harmsen, S; Trani, F

    1991-01-01

    The beta-D-gentiobioside [beta-D-glucopyranosyl(1----6)-beta-D-glucopyranoside] of 3-hydroxy-beta-ionol has been isolated and characterized in quince (Cydonia oblonga) fruit through spectral and chemical studies. Model experiments carried out with this new natural compound revealed its important role as precursor of a number of C13-norisoprenoid flavour compounds of quince essential oil. PMID:1367795

  1. 紫杉醇C13边链的合成%Synthesis of paclitaxel C13 side chain

    Institute of Scientific and Technical Information of China (English)

    赵亚婷; 彭久合; 高瑞昶; 张广明

    2006-01-01

    目的:合成紫杉醇C13边链.方法:反式肉桂酸(1)经单过氧化硫酸氢钾复盐氧化,得到消旋环氧酸(2),化合物2经R-α-苯乙胺拆分、碱化制得钾盐(4),4与叠氮钠的反应产物经酸化得到叠氮酸(5),化合物5用4 mol/L的HCl/MeOH溶液酯化得到叠氮酸甲酯(6),化合物6在含水(15%)四氢呋喃中经Zn/NH4Cl还原、苯甲酰化得到2S-羟基-3S-N-(苯甲酰基)-苯丙酸甲酯(8),化合物8在吡啶中与甲磺酰氯反应即得紫杉醇G13侧链(9).结果:首次以反式肉桂酸(1)为原料制备了紫杉醇C13边链(4S-反式)4,5-二氢-2,4-二苯基-1,3-噁唑-5-甲酸甲酯(9).结论:此方法原料易得,反应条件温和并且成本低,易于生产化生产.

  2. An explanation for the high stability of polycarboxythiophenes in photovoltaic devices—A solid-state NMR dipolar recoupling study

    DEFF Research Database (Denmark)

    Bierring, M.; Nielsen, J.S.; Siu, Ana;

    2008-01-01

    acid carbon atoms were measured by C-13 solid-state magic-angle-spinning (MAS) NMR using symmetry-based double-quantum (2Q) dipolar recoupling. This revealed the presence of C-13-C-13 distances of 3.85 angstrom, which correspond to the C-C distance in hydrogen-bonded carboxylic acid dimers. In spite of...

  3. 26 CFR 31.3306(c)(13)-1 - Services of student nurse or hospital intern.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Services of student nurse or hospital intern. 31.3306(c)(13)-1 Section 31.3306(c)(13)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF...) § 31.3306(c)(13)-1 Services of student nurse or hospital intern. (a) Services performed as a...

  4. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  5. Multi-platform subsystem for controlling acquisition, visualization and data organization of an NMR Digital Spectrometer: ToRM Console; Subsistema multiplataforma para controle de aquisicao, visualizacao e organizacao de dados do Espectrometro Digital de RM: ToRM Console

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Danilo M.D.D. da; Pizetta, Daniel C.; Freire, Guilherme M.; Coelho, Felipe B.; Lourenco, Gustavo V.; Correa, Rodrigo R.M.; Martins, Mateus J.; Vidoto, Edson L.G.; Tannus, Alberto, E-mail: danilomendes@usp.br, E-mail: danilomendesdias@gmail.com [Universidade de Sao Paulo (CIERMag/USP), Sao Carlos, SP (Brazil). Int. de Fisica. Centro de Imagens e Espectroscopia ' in vivo' por Ressonancia Magnetica

    2013-08-15

    In this work, we present the recent results from the development of the CIERMag NMR Digital Spectrometer - a subsystem for controlling acquisition, visualization and data organization. Some aspects of the architecture and features will be shown, including a demonstration with CPMG method for transversal relaxation time (T{sub 2}) measurement using the system. With these achievements, ToRM Console is now being prepared to be an MRI scanner in a near future (author)

  6. An improved method for suppressing protein background in PFG NMR experiments to determine ligand diffusion coefficients in the presence of receptor.

    Science.gov (United States)

    Becker, Bridget A; Morris, Kevin F; Larive, Cynthia K

    2006-08-01

    In NMR diffusion experiments to study ligand-protein binding equilibria, the spectral background due to broad protein resonances can contribute significantly to the measured ligand signal intensity resulting in erroneous binding affinities. One method to suppress the protein spectral background involves coupling a CPMG pulse train before or after the BPPSTE pulse sequence to allow for differential T(2) relaxation of the broad protein resonances. Here, we present an improved method, the Gradient Phase Encoded Spin-lock (GraPES) experiment that integrates the relaxation filter into the diffusion period. Compared with sequential CPMG-BPPSTE pulse sequences, GraPES offers effective suppression of the protein background with improved signal-to-noise ratios and shorter experiment times. PMID:16698296

  7. Study for the charge symmetric systems, 12C+13N and 12C+13C with the orthogonalized coupled-reaction-channel method

    International Nuclear Information System (INIS)

    The charge-symmetric scattering systems, 12C+13N and 12C+13C have been investigated by using the orthogonalized coupled-reaction-channel (OCRC) method with the basis functions of the elastic, inelastic and transfer channels defined by the single-particle states, 1p1/2, 2s1/2, 1d5/2 and 1d3/2 of the valence nucleon in 13N or 13C. The data of the elastic scattering of 13N on 12C measured by Lienard et al. have been explained consistently with the data of the elastic and inelastic scattering of the 12C+13C system. The CRC effects both on the above systems are very strong, although those on the 12C+13N system are fairly weaker than the 12C+13C system. The role of the highly excited single-particle states 1d3/2 is particularly important in the formation of a specific CRC scheme, i.e., the formation of the covalent molecules due to the hybridization caused by the mixing of the different parity single-particle states. The fusion cross sections of the 12C+13C system at energies below the Coulomb barrier are strongly enhanced as a result of the strong CRC effects as compared with those of the 12C+12C system, while in 12C+13N system the enhancement of the sub-barrier fusion has not been observed. The above absorption mechanism for the 12C+13C system explains the lack of the molecular-resonance phenomena observed in the 12C+12C system. We check the effects of the dipole (E1) transition of the valence nucleon in 13N (and also in 13C) due to the core-core Coulomb interaction in the scattering at sub-barrier energies. The effects are not appreciable. (author)

  8. Non-uniform sampling of NMR relaxation data

    DEFF Research Database (Denmark)

    Schwarz-Linnet, Troels; Teilum, Kaare

    2016-01-01

    The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors...... in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of (15)N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance...... reconstructs the non-uniform sampled spectra with high accuracy. For two of the four analyzed datasets, a coverage of only 20 % results in essentially the same results as the fully sampled data. As exemplified by other data, such a low coverage is in general not enough to produce reliable results. We find...

  9. Direct correlation of internal gradients and pore size distributions with low field NMR

    Science.gov (United States)

    Zhang, Yan; Xiao, Lizhi; Liao, Guangzhi; Blümich, Bernhard

    2016-06-01

    Internal magnetic field gradients Gint, which arise from the magnetic susceptibility difference Δχ between solid matrix and fluid in porous media relate to the pore geometry. However, this relationship is complex and not well understood. Here we correlate internal-gradient distributions to pore-size distributions directly to examine internal gradients in detail at low field NMR. The pore-size distributions were obtained by the method of Decay due to Diffusion in the Internal Field (DDIF), and the internal-gradient distributions were measured with the Carr-Purcell-Meiboom-Gill (CPMG) method. The internal-gradient-pore-size distributions correlation maps were obtained for water in packs of glass beads with different diameter and in a sandstone sample. The relationship between internal gradients and pore structure is analyzed in detail by considering the restricted diffusion of fluids in porous samples. For each case diffusion regimes are assigned by plotting normalized CPMG data and comparing the diffusion lengths, the dephasing lengths and pore diameters. In the free-diffusion limit, the correlation maps reveal the true relationship between pore structure and internal gradients so that Δχ can be approximated from the correlation maps. This limit is met most easily at low field. It provides information about porous media, which is expected to benefit the oil industry, in particular NMR well logging.

  10. 26 CFR 1.501(c)(13)-1 - Cemetery companies and crematoria.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Cemetery companies and crematoria. 1.501(c)(13)-1...) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Exempt Organizations § 1.501(c)(13)-1 Cemetery companies and crematoria. (a) Nonprofit mutual cemetery companies. A nonprofit cemetery company may be...

  11. Rapid and simple determination of T1 relaxation times in time-domain NMR by Continuous Wave Free Precession sequence.

    Science.gov (United States)

    Moraes, Tiago Bueno; Monaretto, Tatiana; Colnago, Luiz Alberto

    2016-09-01

    Longitudinal (T1) and transverse (T2) relaxation times have been widely used in time-domain NMR (TD-NMR) to determine several physicochemical properties of petroleum, polymers, and food products. The measurement of T2 through the CPMG pulse sequence has been used in most of these applications because it denotes a rapid, robust method. On the other hand, T1 has been occasionally used in TD-NMR due to the long measurement time required to collect multiple points along the T1 relaxation curve. Recently, several rapid methods to measure T1 have been proposed. Those methods based upon single shot, known as Continuous Wave Free Precession (CWFP) pulse sequences, have been employed in the simultaneous measurement of T1 and T2 in a rapid fashion. However, these sequences can be used exclusively in instrument featuring short dead time because the magnitude of the signal at thermal equilibrium is required. In this paper, we demonstrate that a special CWFP sequence with a low flip angle can be a simple and rapid method to measure T1 regardless of instruments dead time. Experimental results confirmed that the method called CWFP-T1 may be used to measure both single T1 value and T1 distribution in heterogeneous samples. Therefore, CWFP-T1 sequence can be a feasible alternative to CPMG in the determination of physicochemical properties, particularly in processes where fast protocols are requested such as industrial applications. PMID:27376553

  12. Rapid and simple determination of T1 relaxation times in time-domain NMR by Continuous Wave Free Precession sequence

    Science.gov (United States)

    Moraes, Tiago Bueno; Monaretto, Tatiana; Colnago, Luiz Alberto

    2016-09-01

    Longitudinal (T1) and transverse (T2) relaxation times have been widely used in time-domain NMR (TD-NMR) to determine several physicochemical properties of petroleum, polymers, and food products. The measurement of T2 through the CPMG pulse sequence has been used in most of these applications because it denotes a rapid, robust method. On the other hand, T1 has been occasionally used in TD-NMR due to the long measurement time required to collect multiple points along the T1 relaxation curve. Recently, several rapid methods to measure T1 have been proposed. Those methods based upon single shot, known as Continuous Wave Free Precession (CWFP) pulse sequences, have been employed in the simultaneous measurement of T1 and T2 in a rapid fashion. However, these sequences can be used exclusively in instrument featuring short dead time because the magnitude of the signal at thermal equilibrium is required. In this paper, we demonstrate that a special CWFP sequence with a low flip angle can be a simple and rapid method to measure T1 regardless of instruments dead time. Experimental results confirmed that the method called CWFP-T1 may be used to measure both single T1 value and T1 distribution in heterogeneous samples. Therefore, CWFP-T1 sequence can be a feasible alternative to CPMG in the determination of physicochemical properties, particularly in processes where fast protocols are requested such as industrial applications.

  13. Analysis of oil content and oil quality in oilseeds by low-field NMR

    International Nuclear Information System (INIS)

    To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field 1H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T2 values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field 1H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production. (author)

  14. Transport of C-13-labelled linoleic and C-13-labelled caprylic acid in rat plasma after administration of specific structured triacylglycerols

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    transport of dietary C-13-labelled fatty acids in rat plasma to compare the chylomicron fatty acid metabolism after administration of specific structured, long chain and medium chain triacylglycerols. Rats were fed ML*M, M*LM*, L*L*L* or M*M*M* (L=linoleic acid, 18:2n-6, M=caprylic acid, 8:0, * = C-13......The lymphatic transport of structured triacylglycerol consisting of medium and long chain fatty acids in rats has been investigated in several studies, but the following metabolism of the absorbed fatty acids carried in chylomicrons is less elucidated. In the present study we determined the......-labelled fatty acid) by gavage. A maximum transport of 0.5% of the administered C-13-labelled 18:2n-6 was observed in 1mL rat plasma both after administration of L*L*L* and ML*M, while approximately 0.04% of the administered C-13-labelled 8:0 was detected in 1mL plasma following administration of M*M*M* or...

  15. Fusion cross section of 12C+13C at sub-barrier energies

    Science.gov (United States)

    Zhang, N. T.; Tang, X. D.; Chen, H.; Chesneanu, D.; Straticiuc, M.; Trache, L.; Burducea, I.; Li, K. A.; Li, Y. J.; Ghita, D. G.; Margineanu, R.; Pantelica, A.; Gomoiu, C.

    2016-02-01

    In the recent work at Notre Dame, correlations between three carbon isotope fusion systems have been studied and it is found that the fusion cross sections of 12C+13Cand 13C+13C provide an upper limit on the fusion cross section of the astrophysically important 12C+12C reaction.The aim of this work is to continue such research by measuring the fusion cross section of the 12C+13C reaction to lower energies. In this experiment, the off-line activity measurement was performed in the ultra-low background laboratory 12C+13C and the fusion cross section for has been determined in the energy range of Ec.m. =2.5-6.8 MeV. Comparison between this work and several models is also presented.

  16. Origin of the Conformational Modulation of the C-13 NMR Chemical Shift of Methoxy Groups in Aromatic Natural Compounds

    Czech Academy of Sciences Publication Activity Database

    Toušek, J.; Straka, Michal; Sklenář, V.; Marek, R.

    2013-01-01

    Roč. 117, č. 3 (2013), s. 661-669. ISSN 1089-5639 Grant ostatní: Central European Institute of Technology(XE) CZ.1.05/1.1.00/02.0068; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : generalized gradient approximation * intramolecular vanderwaals interactions * polarizable continuum model Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.775, year: 2013

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

    International Nuclear Information System (INIS)

    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

  18. 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

  19. Paramagnetic NMR relaxation in polymeric matrixes: sensitivity enhancement and selective suppression of embedded species (1H and 13C PSR filter).

    Science.gov (United States)

    Fernandez-Megia, Eduardo; Correa, Juan; Novoa-Carballal, Ramon; Riguera, Ricardo

    2007-12-12

    A study of the practical applications of the addition of paramagnetic spin relaxation (PSR) ions to a variety of polymers (PLL, PAA, PGA, PVP, and polysaccharides such as hyaluronic acid, chitosan, mannan, and dextran) in solution (D2O and DMSO-d6) is described. Use of Gd(III), Cu(II), and Mn(II) allows a reduction of up to 500% in the 1H longitudinal relaxation times (T1), and so in the time necessary for recording quantitative NMR spectra (sensitivity enhancement) neither an increase of the spectral line width nor chemical shift changes resulted from addition of any of the PSR agents tested. Selective suppression of the 1H and 13C NMR signals of certain components (low MW molecules and polymers) in the spectrum of a mixture was attained thanks to their different sensitivity [transverse relaxation times (T2)] to Gd(III) (PSR filter). Illustration of this strategy with block copolymers (PGA-g-PEG) and mixtures of polymers and low MW molecules (i.e., lactose-hyaluronic acid, dextran-PAA, PVP-glutamic acid) in 1D and 2D NMR experiments (COSY and HMQC) is presented. In those mixtures where PSR and CPMG filters alone failed in the suppression of certain components (i.e., PVP-mannan-hyaluronic acid) due to their similarity of 1H T2 values and sensitivities to Gd(III), use of the PSR filter in combination with CPMG sequences (PSR-CPMG filter) successfully resulted in the sequential suppression of the components (hyaluronic acid first and then mannan). PMID:18004845

  20. Gastric emptying of a solid meal starts during meal ingestion : Combined study using C-13-octanoic acid breath test and Doppler ultrasonography - Absence of a lag phase in C-13-octanoic acid breath test

    NARCIS (Netherlands)

    Minderhoud, IM; Mundt, MW; Roelofs, JMM; Samsom, M

    2004-01-01

    Scintigraphy and the C-13-octanoic acid breath test are both applied to assess gastric emptying. Using the C-13-octanoic acid breath test, excretion curves show C-13 excretion immediately after ingestion of a solid egg meal, in contrast with scintigraphy where gastric emptying is observed after a la

  1. Compact NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bluemich, Bernhard; Haber-Pohlmeier, Sabina; Zia, Wasif [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMC)

    2014-06-01

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

  2. Compact NMR

    International Nuclear Information System (INIS)

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

  3. Budding yeast cDNA sequencing project: S03036-24_C13 [Budding yeast cDNA sequencing project

    Lifescience Database Archive (English)

    Full Text Available S03036-24_C 13 - - - Show S03036-24_C 13 Seqid S03036-24_C 13 Link to SGD - Link to dbEST - Link to ... UC SC ... Genome Browser - Sequenc e >S03036-24_C 13.phd NNN ... NNNNNNNNNNNNNNANNNNNNNNTGNNGGNNNNNTNNNNNN ANTTGNTATC GAC TTNNTTCC NNNNGAGANNNNNNTGGANAANGANGAGNNNNNGNANAC ... TTNNGANAAANANNC NNANGGTGAGAGCC AGATCC NNNNNNGC GGATTGNGAGC AAATC G TTAAG ... TTC AGGTC AAGTAAAAATTGATTTC NAAAAC TAATTTC TC TTATAC NANNNTTT ...

  4. The 12C/13C ratio in stellar atmospheres. VI. Five luminous cool stars

    International Nuclear Information System (INIS)

    The isotopic abundance ratio, 12C/13C, is derived from the CO vibration rotation lines at 1.6 and 2.3 μ for five cool luminous stars by a simple curve-of-growth technique. A new analysis of CN lines at 8000 A is also described for α Sco and α Ori. Results derived independently from CO and CN are in agreement. Final results are 12C/13C=7 +- 2(α Ori), 12 +- 3(α Sco), 7 +- 3(β Peg), 25 +- 7(chi Cyg), 17 +- 4(α Her), and 7 +- 1.5(α Boo). The α Boo analysis provides a check on the CO curve-of-growth technique; the 12C/13C ratio from the 2.3 μ CO lines is in good agreement with the previously determined ratio from CN and CH lines

  5. Cobwebs of Ophiuchus. I. Strands of (C-13)O - the mass distribution

    International Nuclear Information System (INIS)

    A 4.5 deg x 6.5 deg area of the Rho Ophiuchus molecular complex has been mapped in J = 1-0 (C-13)O with a 2.4 arcmin beam. The spatial distribution of (C-13)O, the distribution of clumps according to size, mass, density, and kinetic temperature are described. The distribution of material in the cloud is compared with the magnetic field distribution and with a shocked cloud model. Evidence supporting the role of shock in the cloud is found in the cloud morphology. 48 references

  6. Adulteration of honey : relation between microscopic analysis and delta C-13 measurements

    NARCIS (Netherlands)

    Kerkvliet, JD; Meijer, HAJ

    2000-01-01

    Upon routine microscopic analysis of some honey samples, parenchyma cells, single rings of ring vessels and epidermal cells are found. These cells originate from the sugar cane stem. We investigated whether there was a relation between these plant fragments and the delta C-13 value of honey. 17 hone

  7. Probing the possibility of a 12C13C abundance gradient from observations of interstellar CH+

    International Nuclear Information System (INIS)

    I have performed high signal-to-noise (SN /equals/ 300 to 500) observations of interstellar CH/sup /plus// at Lick Observatory and at CTIO of the reddened, early-type stars HD 183143, HD 24432, and HD 157038 in an effort to probe the existence of a 12C13C abundance gradient in our Galaxy

  8. Stereoselective synthesis of the C1–C13 segment of dolabelide B

    OpenAIRE

    Keck, Gary E.; McLaws, Mark D.

    2005-01-01

    The efficient construction of the C1–C13 segment of dolabelide B is described. A key element of the synthesis entails BITIP catalyzed asymmetric methallylation to establish the C7 stereocenter, which was then used to direct the stereoselective installation of the C9 and C11 centers through Evans reduction and 1,5-anti aldol condensation, respectively.

  9. Particulate organic matter delta C-13 variations across the Drake Passage

    Science.gov (United States)

    Rau, G. H.; Takahashi, T.; Des Marais, D. J.; Sullivan, C. W.

    1991-01-01

    Particulate organic matter (POM) was sampled during two cruise transects across the Drake Passage during March 1986 to investigate the unusual C-13 depletion in high-latitude Southern Ocean plankton. This POM delta C-13 transition from -23.2 o/oo at 53.3 deg S to values as low as -30.3 o/oo at above 62 deg S does not track previously reported abrupt changes in water chemistry and plankton species composition associated with the Polar Front Zone. The north-south isotopic trend is not accompanied by significant changes in POM carbon or nitrogen concentrations, or in POM C/N. Differences in plankton standing crop or biochemistry (e.g. lipid content) do not appear responsible for the isotopic trends observed. The latitudinal change in POM delta C-13 is highly correlated with water temperature and with the calculated concentration of CO2 (aq) at equilibrium with atmospheric CO2. These observations are consistent with the hypothesis that CO2 (aq) significantly influences POM delta C-13 in ocean surface waters.

  10. Simulation of interaction of circular clusters C7, C12, C13 with nanographene

    International Nuclear Information System (INIS)

    Interaction of circular carbon clusters C7, C12 and C13 with graphene consisting of 272 atoms has been studied by computer simulation based on the Monte Carlo method. The mutual arrangement of the cluster atoms and graphene and their cohesive energy before and after their interaction have been investigated. (author)

  11. Metabolic network analysis of Penicillium chrysogenum using C-13-labeled glucose

    DEFF Research Database (Denmark)

    Christensen, Bjarke; Nielsen, Jens

    2000-01-01

    Using C-13-labeled glucose fed to a penicillin-overproducing strain of Penicillium chrysogenum, the intracellular fluxes were quantified, and the presence of two new pathways, not previously described in this organism, is suggested. Thus, glycine was synthesized not only by serine hydroxymethyltr...

  12. Impact of transamination reactions and protein turnover on labeling dynamics in C-13-labeling experiments

    DEFF Research Database (Denmark)

    Grotkjær, Thomas; Åkesson, M.; Christensen, Bjarke;

    2004-01-01

    A dynamic model describing carbon atom transitions in the central metabolism of Saccharomyces cerevisiae is used to investigate the influence of transamination reactions and protein turnover on the transient behavior of C-13-labeling chemostat experiments. The simulations performed suggest that c...

  13. Microscale simulations of NMR relaxation in porous media

    Science.gov (United States)

    Mohnke, Oliver; Klitzsch, Norbert

    2010-05-01

    ). In this respect substantial coupling effects in typical porous rocks can be observed at pore sizes about magnetic field gradients in rocks arise due to susceptibility contrasts in pore fluid and rock matrix and depend on the magnetic field strength (Larmor frequency). To model the increased relaxation rate observed in CPMG measurements due to diffusive motion in a magnetic (internal) gradient field the simulations are coupled with calculations of spatial distribution of field gradients within the simulated fluid-matrix system according to Ampere's law. Contrary to common assumptions of a constant ratio between T1 and T2 in petrophysical NMR the CPMG simulations in the presence of internal gradients show a significant increase of T1/T2 ratios with decreasing pore sizes. This implies a shift of derived signal contributions to smaller pore sizes, e.g. oil, to study basic correlations between NMR and hydrological parameters of partially saturated rocks. This study was conducted within the framework of the Transregional Collaborative Research Centre 32, funded by the German Research Foundation (DFG).

  14. Proton NMR study of water permeability of hepatocyte membrane

    International Nuclear Information System (INIS)

    It is known that Nuclear Magnetic Resonance (NMR) relaxation methods may provide useful information regarding the permeability of the cell membrane. In the case of erythrocyte membrane, the NMR relaxation methods put in evidence the permeability changes due to different diseases or to chronic internal irradiation. The aim of this work was to investigate the water transport across the normal and oncological stressed hepatocyte membrane and to evaluate in which extend the T2 - NMR may reveal permeability changes due to the oncological factor. Isolated hepatocytes were obtained from Wistar male rat liver using a two phase perfusion technique with collagenase. The oncogenic stress was induced by acute administration of 2 - acetaminofluorene (2-AAF), 20 mg per body weight, twice in 48 hours before liver extraction. The cell viability after isolation was assessed by trypan blue exclusion. The NMR measurements were carried out on hepatocytes suspension doped with a relaxation agent (8 mM Mn Cl2). The transversal relaxation functions were determined for temperatures within the range 7 - 40 deg. C, using the standard CPMG pulse sequence. For all investigated temperatures the relaxation curves have a biexponential behavior corresponding to the water exchange between inner (A) and outer (B) cell compartments. The apparent relaxation times, T2A, T2B were obtained from experimental data via Singular Value Decomposition fitting and were used to determine experimentally the mean lifetime value of water molecules inside the liver cells. Since T may be directly related to the permeability of the membrane by P = (V/A)/T, it results that the oncogenic stress induces an increase of membrane water permeability accompanied by the change of activation energy. Therefore one may conclude that the acute administration of 2 - AAF induces conformation changes of the membrane structure which significantly affects the water transport process across the membrane

  15. Comparative study of inversion methods of three-dimensional NMR and sensitivity to fluids

    Science.gov (United States)

    Tan, Maojin; Wang, Peng; Mao, Keyu

    2014-04-01

    Three-dimensional nuclear magnetic resonance (3D NMR) logging can simultaneously measure transverse relaxation time (T2), longitudinal relaxation time (T1), and diffusion coefficient (D). These parameters can be used to distinguish fluids in the porous reservoirs. For 3D NMR logging, the relaxation mechanism and mathematical model, Fredholm equation, are introduced, and the inversion methods including Singular Value Decomposition (SVD), Butler-Reeds-Dawson (BRD), and Global Inversion (GI) methods are studied in detail, respectively. During one simulation test, multi-echo CPMG sequence activation is designed firstly, echo trains of the ideal fluid models are synthesized, then an inversion algorithm is carried on these synthetic echo trains, and finally T2-T1-D map is built. Futhermore, SVD, BRD, and GI methods are respectively applied into a same fluid model, and the computing speed and inversion accuracy are compared and analyzed. When the optimal inversion method and matrix dimention are applied, the inversion results are in good aggreement with the supposed fluid model, which indicates that the inversion method of 3D NMR is applieable for fluid typing of oil and gas reservoirs. Additionally, the forward modeling and inversion tests are made in oil-water and gas-water models, respectively, the sensitivity to the fluids in different magnetic field gradients is also examined in detail. The effect of magnetic gradient on fluid typing in 3D NMR logging is stuied and the optimal manetic gradient is choosen.

  16. Chemical vs. biotechnological synthesis of C13-apocarotenoids: current methods, applications and perspectives.

    Science.gov (United States)

    Cataldo, Vicente F; López, Javiera; Cárcamo, Martín; Agosin, Eduardo

    2016-07-01

    Apocarotenoids are natural compounds derived from the oxidative cleavage of carotenoids. Particularly, C13-apocarotenoids are volatile compounds that contribute to the aromas of different flowers and fruits and are highly valued by the Flavor and Fragrance industry. So far, the chemical synthesis of these terpenoids has dominated the industry. Nonetheless, the increasing consumer demand for more natural and sustainable processes raises an interesting opportunity for bio-production alternatives. In this regard, enzymatic biocatalysis and metabolically engineered microorganisms emerge as attractive biotechnological options. The present review summarizes promising bioengineering approaches with regard to chemical production methods for the synthesis of two families of C13-apocarotenoids: ionones/dihydroionones and damascones/damascenone. We discuss each method and its applicability, with a thorough comparative analysis for ionones, focusing on the production process, regulatory aspects, and sustainability. PMID:27154347

  17. Stellar Origins of C-13 and N-15-Enriched Presolar SiC Grains

    Science.gov (United States)

    Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua; Pignatari, Marco; Jose, Jordi; Nguyen, Ann

    2016-01-01

    Extreme excesses of 13 C ( C (12 C/ 13 CSiC 20) in rare presolar SiClar SiC grains have been considered diagnostic of an origin in classical novae [1], though an origin in core-collapse supernovae (CCSNe) has also been proposed [2]. We report multi-element isotopic data for 19 13 C- and 15 N-enriched presolar SiC grains(12 C/13 C<16 and 14 N/ 15 N<150) from an acid resistant residue of the Murchison meteorite. These grains are enriched in 13 C and15 N, but with quite diverse Si isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures.

  18. Four-dimensional 13C/13C-edited nuclear Overhauser Enhancement Spectroscopy of a protein in solution: Application to interleukin 1β

    International Nuclear Information System (INIS)

    A four-dimensional 13C/13C-edited NOESY experiment is described which dramatically improves the resolution of protein NMR spectra and enables the straightforward assignment of nuclear Overhauser effects involving aliphatic and/or aromatic protons in larger proteins. The experiment is demonstrated for uniformly (>95%) 13C-labeled interleukin 1β, a protein of 153 residues and 17.4 kDa, which plays a key role in the immune response. NOEs between aliphatic and/or aromatic protons are first spread out into a third dimension by the 13C chemical shift of the carbon atom attached to the originating proton and subsequently into a fourth dimension by the 13C chemical shift of the carbon atom attached to the destination proton. Thus, each NOE cross peak is labeled by four chemical shifts. By this means, ambiguities in the assignment of NOEs that arise from chemical shift overlap and degeneracy are completely removed. Further, NOEs between protons with the same chemical shifts can readily be detected providing their attached carbon atoms have different 13C chemical shifts. The design of the pulse sequence requires special care to minimize the level of artifacts arising from undesired coherence transfer pathways, and in particular those associated with diagonal peaks which correspond to magnetization that has not been transferred from one proton to another. The 4D 13C/13C-edited NOESY experiment is characterized by high sensitivity as the through-bond transfer steps involve the large 1JCH (130 Hz) couplings, and it is possible to obtain high-quality spectra on 1-2 mM samples of 13C-labeled protein in as little as 3 days. This experiment should open up the application of protein structure determination by NMR to a large number of medium-sized proteins (150-300 residues) of biological interest

  19. NMR spectroscopy

    International Nuclear Information System (INIS)

    The book reviews the applications of NMR-spectroscopy in medicine and biology. The first chapter of about 40 pages summarizes the history of development and explains the chemical and physical fundamentals of this new and non-invasive method in an easily comprehensible manner. The other chapters summarize diagnostic results obtained with this method in organs and tissues, so that the reader will find a systematic overview of the available findings obtained in the various organ systems. It must be noted, however, that ongoing research work and new insight quite naturally will necessitate corrections to be done, as is the case here with some biochemical interpretations which would need adjustment to latest research results. NMR-spectroscopy is able to measure very fine energy differences on the molecular level, and thus offers insight into metabolic processes, with the advantage that there is no need of applying ionizing radiation in order to qualitatively or quantitatively analyse the metabolic processes in the various organ systems. (orig./DG) With 40 figs., 4 tabs

  20. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    Science.gov (United States)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  1. Solid-State NMR Examination of Alteration Layers on a Nuclear Waste Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Kelly A. [Penn State Univ., State College, PA (United States). Dept. of Chemistry; Washton, Nancy M. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Science Lab.; Ryan, Joseph V. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pantano, Carlo G. [Penn State Univ., State College, PA (United States). Dept. of Materials Science and Engineering; Mueller, Karl T. [Penn State Univ., State College, PA (United States). Dept. of Chemistry; Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Science Lab.

    2013-06-01

    Solid-state NMR is a powerful tool for probing the role and significance of alteration layers in determining the kinetics for the corrosion of nuclear waste glass. NMR methods are used to probe the chemical structure of the alteration layers to elucidate information about their chemical complexity, leading to increased insight into the mechanism of altered layer formation. Two glass compositions were examined in this study: a glass preliminarily designed for nuclear waste immobilization (called AFCI) and a simplified version of this AFCI glass (which we call SA1R). Powdered glasses with controlled and known particles sizes were corroded at 90 °C for periods of one and five months with a surface-area to solution-volume ratio of 100,000 m-1. 1H-29Si CP-CPMG MAS NMR, 1H-27Al CP-MAS NMR, 1H-11B CP-MAS NMR, and 1H-23Na CP-MAS NMR experiments provide isolated structural information about the alteration layers, which differ in structure from that of the pristine glass. Both glasses studied here develop alteration layers composed primarily of [IV]Si species. Aluminum is also retained in the alteration layers, perhaps facilitated by the observed increase in coordination from [IV]Al to [VI]Al, which correlates with a loss of charge balancing cations. 1H-11B CP-MAS NMR observations indicated a retention of boron in hydrated glass layers, which has not been characterized by previous work. For the AFCI glass, secondary phase formation begins during the corrosion times considered here, and these neophases are detected within the alteration layers. We identify precursor phases as crystalline sodium metasilicates. An important finding is that layer thickness depends on the length of the initial alteration stages and varies only with respect to silicon species during the residual rate regime.

  2. Solid-State NMR Examination of Alteration Layers on a Nuclear Waste Glasses

    International Nuclear Information System (INIS)

    Solid-state NMR is a powerful tool for probing the role and significance of alteration layers in determining the kinetics for the corrosion of nuclear waste glass. NMR methods are used to probe the chemical structure of the alteration layers to elucidate information about their chemical complexity, leading to increased insight into the mechanism of altered layer formation. Two glass compositions were examined in this study: a glass preliminarily designed for nuclear waste immobilization (called AFCI) and a simplified version of this AFCI glass (which we call SA1R). Powdered glasses with controlled and known particles sizes were corroded at 90 °C for periods of one and five months with a surface-area to solution-volume ratio of 100,000 m-1. 1H-29Si CP-CPMG MAS NMR, 1H-27Al CP-MAS NMR, 1H-11B CP-MAS NMR, and 1H-23Na CP-MAS NMR experiments provide isolated structural information about the alteration layers, which differ in structure from that of the pristine glass. Both glasses studied here develop alteration layers composed primarily of [IV]Si species. Aluminum is also retained in the alteration layers, perhaps facilitated by the observed increase in coordination from [IV]Al to [VI]Al, which correlates with a loss of charge balancing cations. 1H-11B CP-MAS NMR observations indicated a retention of boron in hydrated glass layers, which has not been characterized by previous work. For the AFCI glass, secondary phase formation begins during the corrosion times considered here, and these neophases are detected within the alteration layers. We identify precursor phases as crystalline sodium metasilicates. An important finding is that layer thickness depends on the length of the initial alteration stages and varies only with respect to silicon species during the residual rate regime

  3. Structural study of pyrones by NMR

    International Nuclear Information System (INIS)

    Extracts of two species of Aniba, designed Aniba-SA (light petroleum extract) and Aniba-SB (benzene extract), afforded by chromatographic fraccionation some compounds. The isolated compounds were identified using spectrometric data and C13-NMR coupled and decompled spectra of pyrones were registered. Measurement of the heteronuclear residual coupling by irradiation proton frequency off-resonance was used for distinguish C-5, C-7 and C-8 carbons of the pyrones SB-1, SB-3, SB-4 and SB-5. (M.J.C.)

  4. The simultaneous biosynthesis and uptake of amino acids by Lactococcus lactis studied by C-13-labeling experiments

    DEFF Research Database (Denmark)

    Jensen, N.B.S.; Christensen, B.; Nielsen, Jette;

    2002-01-01

    Uniformly C-13 labeled glucose was fed to a lactic acid bacterium growing on a defined medium supplemented with all proteinogenic amino acids except glutamate. Aspartate stemming from the protein pool and from the extracellular medium was enriched with C-13 disclosing a substantial de novo biosyn...

  5. Valence neutrons' role in the collisions 13C+12C and 13C+13C

    International Nuclear Information System (INIS)

    The resonant behaviour is not limited to collisions between α-like nuclei: resonance structures have been observed in the direct channels for the 13C+12C and 13C+13C collisions; in the contrary, the resonances observed in the fusion channels are not so pronounced as in the 12C+12C case: the valence neutrons increase the number of reaction channels and the density of states in the states in the compound nuclei, the resonances are therefore 'washed out' and it is difficult to observe them experimentally

  6. C-13 relaxation time gradients in complexes of linear oligosaccharides and cyclodextrin

    International Nuclear Information System (INIS)

    A non-destructive method for sugar sequence determination is suggested using C-13 relaxation time gradients which are observable when the center of mass of the molecule is shifted by complexation with cyclodextrin. Quick and precise T1 measurements can be done in reasonable machine time because of the high solubility of simple methylated derivatives of cyclodextrin in water and because of the 1:1 host-guest ratio. A relaxation time gradient of more than 20% has been reported for a benzyl trisaccharide complex. (author)

  7. NMR-CT of cerebrovascular diseases using pulse sequence of Carr-Purcell-Meiboom-Gill method

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance-computed tomography (NMR-CT) findings of 114 cases of cerebrovascular diseases are reported. The NMR-CT used for this study was a product of Bruker Company in West Germany. It has a 0.15 tesla resistive magnet, using the pulse sequence of the Carr-Purcell-Meiboom-Gill (CPMG) method. Intracerebral hematoma showing iso- or low density on X-ray CT could be detected by NMR-CT in the subacute stage and even in the chronic stage. T1 and T2 relaxation times (T1, T2) of hematoma showed prolongation as time passed from about 2 weeks after the onset. NMR-CT detected small or lacunar infarctic lesions at the basal ganglia, the brain stem or the posterior fossa. Prolongations of T1 and T2 in infarctic foci were more marked than in hematomas. In two cases of transient ischemic attack, the responsible lesions were detected by NMR-CT, but no abnormality was found on X-ray CT at the same time. Moreover, as disappearance of the abnormal image and normalization of T1 and T2 in these foci were noted by follow-up NMR-CT after bypass surgery, it was suggested that these lesions were reversible and might be a critical low perfusion area, the so-called ischemic penumbra. NMR-CT findings in moyamoya disease were the same as those obtained by X-ray CT. However, slightly ischemic lesions might be detected by NMR-CT. Therefore, operative indications and effectiveness for ischemic moyamoya disease might be decided by NMR-CT. For arteriovenous malformations (AVMs), NMR-CT was an excellent diagnostic method because the extent of the lesions was easily recognized, and dilated vessels were depicted as low or no signal intensity areas without using contrast media. Three dimensional observation of brain tissues surrounding the AVM was possible by NMR-CT. These areas were depicted as T1 and T2 prolonged regions on calculated NMR images. This finding may indicate ischemic or necrotic changes due to the blood steal phenomena. (J.P.N.)

  8. Non-uniform sampling of NMR relaxation data

    International Nuclear Information System (INIS)

    The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of 15N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition reconstructs the non-uniform sampled spectra with high accuracy. For two of the four analyzed datasets, a coverage of only 20 % results in essentially the same results as the fully sampled data. As exemplified by other data, such a low coverage is in general not enough to produce reliable results. We find that a coverage level not compromising the final results can be estimated by recording a single full two-dimensional spectrum and reducing the spectrum quality in silico

  9. Non-uniform sampling of NMR relaxation data

    Energy Technology Data Exchange (ETDEWEB)

    Linnet, Troels E.; Teilum, Kaare, E-mail: kaare.teilum@bio.ku.dk [University of Copenhagen, SBiNLab and the Linderstrøm-Lang Centre for Protein Science, Department of Biology (Denmark)

    2016-02-15

    The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of {sup 15}N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition reconstructs the non-uniform sampled spectra with high accuracy. For two of the four analyzed datasets, a coverage of only 20 % results in essentially the same results as the fully sampled data. As exemplified by other data, such a low coverage is in general not enough to produce reliable results. We find that a coverage level not compromising the final results can be estimated by recording a single full two-dimensional spectrum and reducing the spectrum quality in silico.

  10. CNONa and 12C/13C in giants of 10 open clusters

    CERN Document Server

    Smiljanic, R; North, P; Barbuy, B; Charbonnel, C; Mowlavi, N

    2008-01-01

    Evolved low-mass stars with a large range in metallicity bear signatures of a non-standard mixing event in their surface abundances of Li, C, N, and in their 12C/13C ratio. A Na overabundance has also been reported in some giants of open clusters but remains debated. Recently, the cause of the extra-mixing has been attributed to thermohaline convection that should take place after the RGB bump for low mass stars and on the early-AGB for more massive objects. In order to track the occurrence of this process over a large mass range, we derive in a homogeneous way the abundances of C, N, O, and Na, as well as the 12C/13C ratio in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to 3.1 Msun. A group of first ascent red giants with M/Msun $\\leq$ 2.5 exhibits smaller [N/C] ratios than those measured in clump giants of the same mass range, suggesting an additional increase of the [N/C] ratio after the first dredge-up. The sodium abundances corrected from NLTE are found to be about solar. [Na/F...

  11. Recoveries of rat lymph FA after administration of specific structured C-13-TAG

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Mu, Huiling; Høy, Carl-Erik

    2003-01-01

    intragastrically administered L*L*L*, M*M*M*, ML*M, and ML*L* (where * = C-13-labeled FA) in rats. Lymph lipids were separated into lipid classes and analyzed by GC combustion isotope ratio MS. The recoveries of lymph TAG 18:2n-6 8 h after administration of L*L*L*, ML*M, and ML*L* were 38.6, 48.4, and 49.......1%, respectively, whereas after 24 h the recoveries were approximately 50% in all experimental groups. The exogenous contribution to lymph TAG 18:2n-6 was approximately 80 and 60% at maximum absorption of the specific structured TAG and L*L*L*, respectively, 3-6 h after administration. The tendency toward more...

  12. Recoveries of rat lymph FA after administration of specific structured C-13-TAG

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Mu, Huiling; Høy, Carl-Erik

    2003-01-01

    intragastrically administered L*L*L*, M*M*M*, ML*M, and ML*L* (where * = C-13-labeled FA) in rats. Lymph lipids were separated into lipid classes and analyzed by GC combustion isotope ratio MS. The recoveries of lymph TAG 18:2n-6 8 h after administration of L*L*L*, ML*M, and ML*L* were 38.6, 48.4, and 49.......1%, respectively, whereas after 24 h the recoveries were approximately 50% in all experimental groups. The exogenous contribution to lymph TAG 18:2n-6 was approximately 80 and 60% at maximum absorption of the specific structured TAG and L*L*L*, respectively, 3-6 h after administration. The tendency toward more...... low stimulation of chylomicron formation. These results demonstrate tendencies toward faster lymphatic recovery of long-chain FA after administration of specific structured TAG compared with long-chain TAG....

  13. NMR studies of metabolism

    International Nuclear Information System (INIS)

    In this paper, the authors present applications of NMR to the study of different aspects of metabolism. The authors begin with a brief outline of localization methods that are commonly used to obtain in vivo NMR spectra. The authors then describe in more detail metabolic information recently obtained by NMR of perfused organs, intact animals, and humans. Previous reviews have already covered the applications of NMR to the study of metabolism in microorganisms, isolated or cultivated cells, and tumors. NMR spectroscopy of the brain, and human in vivo NMR spectroscopy have also been reviewed

  14. The first noncoordinated phosphonium diylide, [Me2P(C13H8)2]-, and its ylidic and cationic counterparts: synthesis, structural characterization, and interaction with the heavy group 2 metals.

    Science.gov (United States)

    Brady, E D; Hanusa, T P; Pink, M; Young, V G

    2000-12-25

    Treatment of potassium or lithium fluorenide with MePCl2 generates the organophosphine MeP(C13H9)2, which on reaction with methyl iodide produces the phosphonium species [Me2P(C13H9)2]I in 74% yield. In the solid state, H...I contacts of product from the reaction with the calcium complex was structurally identified as the salt [CaI(thf)5][Me2P(C13H8)2]. The anion, which is outside the coordination sphere of the calcium, represents the first structurally authenticated example of a free phosphonium diylide. The P-C(ylidic) bond length of 1.748(4) A reflects some partial multiple bond character. 1H and 31P NMR spectra suggest that the barium analogue is similar. Density functional theory calculations were performed on representative phosphonium diylides as an aid to interpreting the bonding in this class of compounds. Despite the strong electrostatic attraction that usually drives metal-ligand binding in highly ionic systems, calcium and barium prefer to coordinate to a single iodide ion and several neutral oxygen donors rather than to the charged diylide. PMID:11188523

  15. NMR analysis of biodiesel

    Science.gov (United States)

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

  16. Applications of artificial intelligence for organic chemistry: analysis of C-13 spectra

    Energy Technology Data Exchange (ETDEWEB)

    Gray, N.A.B.

    1984-01-01

    An expert system has been developed to aid in the analysis of carbon-13 nuclear magnetic resonance (/sup 13/C NMR) spectra of complex organic molecules. This system uses a knowledge base of rules relating substructural and spectral features: these rules are derived automatically from data for known structures. Such rules have a number of current, practical applications relating to spectrum prediction. They also constitute the basis of a method for the structural interpretation of /sup 13/C spectral data of unknown compounds. This method, which is basically a constraint refinement search, provides for a much more complete analysis of such data than any approach currently utilized. 29 references.

  17. Study of α-monosubstituted methyl acetates by C-13 and H-1 Nuclear Magnetic resonance

    International Nuclear Information System (INIS)

    The substituents effects on the methylene and carbonyl carbons chemical shifts of some α-monosubstituted methyl acetates Z-CH2-COOMe(Z=H,Cl,Br,I,OME,SMe,NMe2 and Me) is studied. Some data of Carbon 13 NMr in the light of the substituents empirical and electronic effects are shown. Solvent and concentration effects on the hydrogen-1 chemical shifts of methyl acetate, bromoacetate and Iodoacetate were interpreted in the light of the Cα-C(O)-bond rotational isomerism. (M.J.C.)

  18. Analysis of oil content and oil quality in oilseeds by low-field NMR; Analise do teor e da qualidade dos lipideos presentes em sementes de oleaginosas por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Constantino, Andre F.; Lacerda Junior, Valdemar; Santos, Reginaldo B. dos; Greco, Sandro J.; Silva, Renzo C.; Neto, Alvaro C.; Barbosa, Lucio L.; Castro, Eustaquio V.R. de [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Quimica; Freitas, Jair C.C. [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Fisica

    2014-07-01

    To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field {sup 1}H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T{sub 2} values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field {sup 1}H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production. (author)

  19. Interstellar CN and CH+ in Diffuse Molecular Clouds: 12C/13C Ratios and CN Excitation

    CERN Document Server

    Ritchey, A M; Lambert, D L

    2010-01-01

    We present very high signal-to-noise ratio absorption-line observations of CN and CH+ along 13 lines of sight through diffuse molecular clouds. The data are examined to extract precise isotopologic ratios of 12CN/13CN and 12CH+/13CH+ in order to assess predictions of diffuse cloud chemistry. Our results on 12CH+/13CH+ confirm that this ratio does not deviate from the ambient 12C/13C ratio in local interstellar clouds, as expected if the formation of CH+ involves nonthermal processes. We find that 12CN/13CN, however, can be significantly fractionated away from the ambient value. The dispersion in our sample of 12CN/13CN ratios is similar to that found in recent surveys of 12CO/13CO. For sight lines where both ratios have been determined, the 12CN/13CN ratios are generally fractionated in the opposite sense compared to 12CO/13CO. Chemical fractionation in CO results from competition between selective photodissociation and isotopic charge exchange. An inverse relationship between 12CN/13CN and 12CO/13CO follows ...

  20. Yield and enrichment studies of C-13 isotope by multi-photon dissociation of Freon-22 at low temperatures

    Indian Academy of Sciences (India)

    Manoj Kumar; Anant Deshpande; Chintan Gupta; A K Nath

    2003-06-01

    Multi-photon dissociation of Freon-22 (CF2HCl) at low temperatures has been carried out to separate the C-13 isotope using a TEA CO2 laser. Yield and enrichment of C-13 isotope in the product C2F4 are studied at 9(22) laser line as a function of temperature (-50°C to 30°C). It is observed that at a given fluence when the temperature is lowered the yield decreases and the enrichment factor of C-13 increases. Room temperature irradiation of CF2HCl towards the blue edge of C-13 absorption (i.e. at 9(20) laser line) gives low yield of the product (C2F4) at a fluence, which produces the desired enrichment factor of 100. An increase in fluence gives very high yield of C2F4 but the enrichment factor is very low. Irradiating CF2HCl at a temperature of -10°C enhances the enrichment factor to 100 and the yield obtained is comparable to that towards the red edge of C-13 absorption (i.e. at 9(26) laser line). At a given enrichment factor higher enrichment efficiency is achieved when CF2HCl is irradiated at lower temperature.

  1. A rapid and automated low resolution NMR method to analyze oil quality in intact oilseeds

    International Nuclear Information System (INIS)

    Oilseeds with modified fatty acid profiles have been the genetic alternative for high quality vegetable oil for food and biodiesel applications. They can provide stable, functional oils for the food industry, without the hydrogenation process that produces trans-fatty acid, which has been linked to cardiovascular disease. High yield and high quality oilseeds are also necessary for the success of biodiesel programs, as polyunsatured or saturated fatty acid oil produces biofuel with undesirable properties. In this paper, a rapid and automated low resolution NMR method to select intact oilseeds with a modified fatty acid profile is introduced, based on 1H transverse relaxation time (T 2). The T 2 weighted NMR signal, obtained by a CPMG pulse sequence and processed by chemometric methods was able to determine the oil quality in intact seeds by its fatty composition, cetane number, iodine value and kinematic viscosity with a correlation coefficient r > 0.9. The automated system has the potential to analyze more than 1000 samples per hour and is a powerful tool to speed up the selection of high quality oilseeds for food and biodiesel applications

  2. Metabolic signatures of lung cancer in biofluids: NMR-based metabonomics of blood plasma.

    Science.gov (United States)

    Rocha, Cláudia M; Carrola, Joana; Barros, António S; Gil, Ana M; Goodfellow, Brian J; Carreira, Isabel M; Bernardo, João; Gomes, Ana; Sousa, Vitor; Carvalho, Lina; Duarte, Iola F

    2011-09-01

    In this work, the variations in the metabolic profile of blood plasma from lung cancer patients and healthy controls were investigated through NMR-based metabonomics, to assess the potential of this approach for lung cancer screening and diagnosis. PLS-DA modeling of CPMG spectra from plasma, subjected to Monte Carlo Cross Validation, allowed cancer patients to be discriminated from controls with sensitivity and specificity levels of about 90%. Relatively lower HDL and higher VLDL + LDL in the patients' plasma, together with increased lactate and pyruvate and decreased levels of glucose, citrate, formate, acetate, several amino acids (alanine, glutamine, histidine, tyrosine, valine), and methanol, could be detected. These changes were found to be present at initial disease stages and could be related to known cancer biochemical hallmarks, such as enhanced glycolysis, glutaminolysis, and gluconeogenesis, together with suppressed Krebs cycle and reduced lipid catabolism, thus supporting the hypothesis of a systemic metabolic signature for lung cancer. Despite the possible confounding influence of age, smoking habits, and other uncontrolled factors, these results indicate that NMR-based metabonomics of blood plasma can be useful as a screening tool to identify suspicious cases for subsequent, more specific radiological tests, thus contributing to improved disease management. PMID:21744875

  3. Interaction of hydrated protons with octyl-phenyl-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO): NMR and theoretical study.

    Science.gov (United States)

    Kříž, Jaroslav; Dybal, Jiří; Makrlík, Emanuel; Vaňura, Petr

    2011-10-01

    Interaction of octyl-phenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO, the 'classical' rare metal extraction agent) with fully ionized hydrated protons (HP) was studied in acetonitrile-d(3) using (1)H, (13)C, (31)P NMR, PFG NMR and magnetic relaxation. The experimental results were confronted with high-precision ab initio DFT calculations. Relative chemical shifts of NMR signals of CMPO (0.01 mol/L) under the presence of HP in the molar ratio β = 0-2.0 mol/mol show binding between CMPO and HP. Self-diffusion measurements using (1)H PFG NMR demonstrate that larger complexes with higher content of CMPO are generally formed at β CMPO)(2)·HP (C(2)) and CMPO.HP (C(1)). The logarithms of the respective stabilization constants log K(i) were found to be 7.518 (C(2)) and 4.581 (C(1)). The system dynamics was studied by measuring the transverse (1)H NMR relaxation using CPMG sequence with varying delays t(p) between the π pulses in the mixtures with β = 0.4-0.8. The following exchange correlation times were obtained: τ(10) = 2.35 × 10(-5), τ(20) = 0.82 × 10(-4), τ(21) = 0.45 × 10(-3) s. The DFT calculations support the conclusion that the complexes C(1) and C(2) are the main species in the mixtures of CMPO with HP. They also agree with the NMR and FTIR observation that the main site to which H(3) O(+) is bound is the P=O group, whereas the amide group does not form a strong bond with the ion when excess water molecules are present. PMID:21898583

  4. NMR at 900 MHz

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ An important factor in the development of solutionstate NMR has always been th e ability to produce stable and homogeneous magnetic fields. As higher and higher field strengths are reached the pressure is growing on manufacturers to produce NMR systems with greatly improved spectral resolution and signal to noise ratio. The introduction of the Varian 900 MHz INOVA system in August 2000 featuring Oxford Instruments 21.1 T magnet represents the latest pioneering development in NMR technology.

  5. Characteristic coupling constants 1J(13C-13C) of some mesoionic methylides contaIning a diphenyltetrazolium ring

    OpenAIRE

    Jazwinski, Jaroslaw; Kozminski, Wtktor; stefaniak, Lech; Webl, Graham A.

    1994-01-01

    1J(13C-13C) data are presented for some Types A and B tetrazoliwn methylides. The results show a large amoWlt of double bond character for the C5-C6 bond which is significantly reduced upon protonation. A similar decrease in bond order is noted for the C6-C8 bond following protonation.

  6. Radiation Oxidation Mechanisms in Polyolefins Studied by C-13 Isotopic Labeling

    International Nuclear Information System (INIS)

    Control of oxidative degradation is a critical consideration in most applications involving polymers and radiation. In radiation crosslinking or sterilization, or in the use of polymers in radiation environments (such as nuclear plants), the objective is to minimize degradation as much as possible. In other applications, a controlled, partial degradation is desired to alter processing properties, or to enhance adhesion or solubility. To gain more understanding of the complex processes of radiation oxidation, samples of one important commercial polyolefin, polypropylene, were synthesized in which the three different carbon atoms along the chain were selectively labeled with carbon-13. These samples were subjected to radiation under inert and air atmospheres, and to post-irradiation thermal exposure in air at various temperatures. Analysis of macromolecular radiation-oxidation products was carried out using 13C NMR and FTIR. Time-dependent plots of oxidation products have been obtained from the NMR measurements, including the post-irradiation oxidation of a sample held at room temperature in air that has been monitored for 2 years. Analysis of volatile oxidation products (CO, CO2, and small organic molecules) was accomplished with gas chromatography / mass spectroscopy. The position of the 13C labels in the degradation products, have been traced back to their positions of origin on the macromolecule, providing insights into the chemical reaction mechanisms through which the products were formed. The major solid-phase products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of macromolecular products arising from reactions at the methyl side chain. Significant temperature-dependent differences are

  7. {sup 1} H and {sup 13} C NMR of phenyl barbiturilidene; RMN de H-1 e C-13 de fenil barbiturilidenos

    Energy Technology Data Exchange (ETDEWEB)

    Villar, Jose Daniel Figueroa; Santos, Nedina Lucia dos; Cruz, Elizabete Rangel [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

    1991-12-31

    The condensation of barbituric acids with aromatic aldehydes gives the phenyl barbiturilidenes, which are studied as intermediary compounds in the synthesis of new heterocyclic compounds for pharmaceutical use. One of the most characteristic reactions of these compounds is the Michael type addition reaction, in the exocyclic carbon-carbon double binding. The reaction with 2,4-di nitrophenyl hydrazine reaction is been used as a test of this type of reactivity, which supplies the respective hydrazone and barbituric acid. In this work, preliminary studies have been performed for establishing correlations between the Brown parameter ({sigma}{sup +}), the chemical shifts ({delta}) of the barbiturilidene atoms involved in the reaction, and their reactivities 3 refs., 1 fig., 6 tabs.

  8. High-Frequency C-13 and Si-29 NMR Chemical Shifts in Diamagnetic Low-Valence Compounds of TII and Pb-II: Decisive Role of Relativistic Effects

    Czech Academy of Sciences Publication Activity Database

    Vícha, J.; Marek, R.; Straka, Michal

    2016-01-01

    Roč. 55, č. 4 (2016), s. 1770-1781. ISSN 0020-1669 R&D Projects: GA ČR(CZ) GA14-03564S Institutional support: RVO:61388963 Keywords : density functional theory * transition metal complexes * closed-shell interactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.762, year: 2014

  9. C-13 isotopic studies of the surface catalysed reactions of methane

    International Nuclear Information System (INIS)

    The ability of methane to methylate aromatic compounds, which are considered to be models for coal, is being studied. Related to this reaction, but at higher temperatures, is the direct formation of benzene from methane in the presence of these catalysts. Controversy exists in the literature on the former reaction, and 13C isotope studies are being used to resolve the question. The interest in this reaction arises because the utilisation of methane, in the form of natural gas, in place of hydrogen for direct coal liquefaction would have major economic advantage. For this reason Isotope studies in this area have contributed significantly to an understanding of the methylation reactions. The paper describes experiments utilising methane13C, which show that methylation of aromatics such as naphthalene by the methane13C is catalysed by microporous, Cu-exchanged SAPO-5, at elevated pressures (6.8 MPa) and temperatures around 400 degree C. The mass spectrometric analysis and n.m.r. study of the isotopic composition of the products of the methylation reaction demonstrate unequivocally that methane provides the additional carbon atom for the methylated products. Thermodynamic calculations predict that the reaction is favourable at high methane pressures under these experimental conditions. The mechanism as suggested by the isotope study is discussed. The catalysts which show activity for the activation of methane for direct methylation of organic compounds, such as naphthalene, toluene, phenol and pyrene, are substituted aluminophosphate molecular sieves, EIAPO-5 (where El=Pb, Cu, Ni and Si) and a number of metal substituted zeolites. Our earlier tritium studies had shown that these catalysts will activate alkanes, at least as far as isotope hydrogen exchange reactions are concerned

  10. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

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

  11. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

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

  12. Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

    Science.gov (United States)

    Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

    2016-02-01

    0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

  13. Characterization and differentiation of seven vinhos verdes grape varieties on the basis of monoterpenic and C13-norisoprenoid compounds

    OpenAIRE

    Genisheva, Zlatina Asenova; Vilanova, Mar; Oliveira, J.M.

    2008-01-01

    Les profils aromatiques des 7 cépages recommandés pour la production de Vinho Verde ont été établis en ce qui concerne les C13-norisoprenoïdes et les composés monoterpéniques, trouvés dans les deux fractions de l´arôme, livre et glycosillée. Dix-huit monoterpènes ont été identifiés et quantifiées, dans la fraction libre, et d’autres 22 attachés à des glycosides. Quinze C13-norisoprenoïdes ont été identifiés et quantifiés dans la fraction glycosillée. Le cépage Loureiro peut fac...

  14. Metabonomic study of human serum in gallbladder cancer by 1H NMR spectroscopy

    International Nuclear Information System (INIS)

    Gallbladder carcinoma (GBC) is one of the most lethal malignancies of upper gastrointestinal tract and it has the highest mortality rate in Chile and India. It has a very high incidence rates in northern India therefore it is also called as an Indian disease. There are several factors which play important role in development of gallbladder cancer including long-standing stones in gallbladder and alterations in composition of bile. Studies on gallstones and gallbladder tissues revealed that benign group can easily be discriminated from malignant group. Many proteomic studies have been performed for different cancers and several responsible serum protein markers have been identified but there is no such metabonomics study that shows the presence of any biomarker associated with gallbladder carcinoma. Identification of such biomarker would help immensely in the diagnostic of GBC. For this study we have collected blood samples (70; including patients from Chronic Cholecystitis (CC), XanthoGranulomatous Cholecystitis (XGC) and Gallbladder Cancer (GBC)) post-operatively (immediately after surgery) from patient undergoing cholecystectomy in Department of Surgical Gastroenterology, SGPGIMS. Control samples were also collected from 20 volunteers after 12 hrs of fasting. 4 ml of blood sample was collected and was allowed to clot in plastic tube for 30 min at room temperature in incubator. The serum was collected by centrifugation and samples were stored at -80 deg C till NMR experiments. 400 μL of serum was used for recording NMR spectra. NMR spectra were recorded at Bruker Avance 800 MHz spectrometer using CPMG pulse sequence with water presaturation. Control serum shows presence of various amino acids and low molecular weight metabolites. Detailed multivariate analysis along with markers found in serum associated with GBC will be presented. (author)

  15. Functional studies using NMR

    International Nuclear Information System (INIS)

    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

  16. Renal transplant NMR

    International Nuclear Information System (INIS)

    The preliminary results of NMR evaluation of renal transplants (Txs) are reported including correlation with nuclear medicine (NM) and ultrasound (US). Thirteen Txs (8 cadaver (Cd), 5 living related doner (LRD) in 13 patients (6M, 7F) ranging in age from 25-47 (x 35) were evaluated by NM (32), NMR (15) and US (5). Clinical diagnoses included: rejection (8), ATN (2), infarction (1), and normal (2). Of the 8 patients with rejection (5) Cd; 3 LRD) pathologic proof was obtained in 3. An experimental 0.12 T resistive magnet (GE) was used with a partial saturation technique with repetition time (TR) of 143 and 286 msec to provide T1 weighting. T2 weighted information was obtained with a spin echo technique with echo times (TE) of 20, 40, 60 and 80 msec. The NMR appearance of normal Txs consisted of a uniform signal intensity (Tx> pelvic musculature), well-defined internal architecture with good cortical medullary differentiation and normal appearing vessels. The NMR appearance of abnormal transplants consisted of a heterogeneous or overall decrease in signal intensity (kidney muscle) with poor cortical medullary differentiation with or without a halo of decreased signal intensity. Although NMR was able to differentiate normal from abnormal, it was unable to clearly discriminate between ATN and rejection. Advantages of NMR included the ability to demonstrate regional anatomy, vasculature, post operative fluid collections and hematomas, and associated avascular necrosis of the hips

  17. 鲜花生的低场核磁共振横向弛豫分析%Low Field NMR Transverse Relaxation Spectrum of Peanut

    Institute of Scientific and Technical Information of China (English)

    李潮锐; 刘青; 杨培强

    2014-01-01

    As low field 1 H NMR relaxation can effectively measure moisture and fat in oil seed,the key problem is technology for identification of the contribution from these components respectively.The pea-nut mass change with hydrogenation is recorded for optimizing NMR measurement process.The CPMG (Carr-Purcell-Meiboom-Gill) technique was applied to obtain the NMR transverse relaxation of peanut and peanut oil samples,and the resonance relaxation spectrum was analyzed with the method of continu-ous spectrum iteration.According to the variation of relaxation spectrum peak area with peanut mass,the assignments of the relaxation peaks were determined with the results from peanut oil.The study found that the transverse relaxation spectrum peaks reflected the fat content in dry peanut.Compared with fat con-tent measured with traditional technology,the peak areas for dry fresh peanut had a positive linear corre-lation with its fat concentration.The results demonstrate that the NMR transverse relaxation spectrum can be used for determination of fat content in fresh peanut.%尽管低场1 H-核磁共振(NMR)弛豫谱技术可以有效地获取油料作物种子中水和油脂等组分含量信息,但实现准确分析的关键前提是解决弛豫谱的标识问题。首先,通过记录鲜花生脱水过程质量随时间变化确定核磁共振测量步骤;随之,采用CPMG (Carr-Purcell-Meiboom-Gill)方法获得花生核磁共振横向弛豫数据;最后,使用连续谱迭代方法得到花生核磁共振弛豫谱。由弛豫谱峰面积与花生质量变化关系,并借助纯花生油实验结果确认了样品脂肪的核磁共振横向弛豫谱。基于单位质量干燥花生和纯花生油两者的脂肪弛豫谱峰面积之比获得与索氏抽提法相吻合的含油率。

  18. Metabolic network analysis on Phaffia rhodozyma yeast using C-13-labeled glucose and gas chromatography-mass spectrometry

    DEFF Research Database (Denmark)

    Cannizzaro, C.; Christensen, B.; Nielsen, Jens;

    2004-01-01

    Carotenoid production by micro organisms, as opposed to chemical synthesis, could fulfill an ever-increasing demand for 'all natural' products. The yeast Phaffia rhodozyma has received considerable attention because it produces the red pigment astaxanthin, commonly used as an animal feed supplement....... In order to have a better understanding of its metabolism, labeling experiments with [1-C-13]glucose were conducted with the wildtype strain (CBS5905T) and a hyper-producing carotenoid strain (J4-3) in order to determine their metabolic network structure and estimate intracellular fluxes. Amino acid...

  19. NMR Aerosolomics: Novel NMR Method for Organic Aerosol Analysis

    Czech Academy of Sciences Publication Activity Database

    Horník, Štěpán; Schwarz, Jaroslav; Sýkora, Jan

    - : -, 2015, s. 162. ISBN N. [Small Molecule NMR Conference - SMASH 2015. Baveno (IT), 20.09.2015-23.09.2015] Institutional support: RVO:67985858 Keywords : aerosol * analysis * NMR Subject RIV: CC - Organic Chemistry

  20. Solid-, Solution-, and Gas-state NMR Monitoring of 13C-Cellulose Degradation in an Anaerobic Microbial Ecosystem

    Directory of Open Access Journals (Sweden)

    Yasuhiro Date

    2013-07-01

    Full Text Available Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. 13C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and 13C-13C/13C-12C isotopomers in the microbial degradation of 13C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid.

  1. NMR imaging technique

    International Nuclear Information System (INIS)

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

  2. An NMR and ab initio quantum chemical study of acid-base equilibria for conformationally constrained acidic alpha-amino acids in aqueous solution

    DEFF Research Database (Denmark)

    Nielsen, Peter Aadal; Jaroszewski, Jerzy W.; Norrby, Per-Ola;

    2001-01-01

    The protonation states of a series of piperidinedicarboxylic acids (PDAs), which are conformationally constrained acidic alpha -amino acids, have been studied by C-13 NMR titration in water. The resulting data have been correlated with theoretical results obtained by HF/6-31+G* calculations using...

  3. Accurate determination of the fine-structure intervals in the 3P ground states of C-13 and C-12 by far-infrared laser magnetic resonance

    Science.gov (United States)

    Cooksy, A. L.; Saykally, R. J.; Brown, J. M.; Evenson, K. M.

    1986-01-01

    Accurate values are presented for the fine-structure intervals in the 3P ground state of neutral atomic C-12 and C-13 as obtained from laser magnetic resonance spectroscopy. The rigorous analysis of C-13 hyperfine structure, the measurement of resonant fields for C-12 transitions at several additional far-infrared laser frequencies, and the increased precision of the C-12 measurements, permit significant improvement in the evaluation of these energies relative to earlier work. These results will expedite the direct and precise measurement of these transitions in interstellar sources and should assist in the determination of the interstellar C-12/C-13 abundance ratio.

  4. Accurate determination of the fine-structure intervals in the 3P ground states of C-13 and C-12 by far-infrared laser magnetic resonance

    International Nuclear Information System (INIS)

    Accurate values are presented for the fine-structure intervals in the 3P ground state of neutral atomic C-12 and C-13 as obtained from laser magnetic resonance spectroscopy. The rigorous analysis of C-13 hyperfine structure, the measurement of resonant fields for C-12 transitions at several additional far-infrared laser frequencies, and the increased precision of the C-12 measurements, permit significant improvement in the evaluation of these energies relative to earlier work. These results will expedite the direct and precise measurement of these transitions in interstellar sources and should assist in the determination of the interstellar C-12/C-13 abundance ratio. 16 references

  5. Impact of reduction on the properties of metal bisdithiolenes: multinuclear solid-state NMR and structural studies on Pt(tfd)2 and its reduced forms.

    Science.gov (United States)

    Tang, Joel A; Kogut, Elzbieta; Norton, Danielle; Lough, Alan J; McGarvey, Bruce R; Fekl, Ulrich; Schurko, Robert W

    2009-03-19

    Transition-metal dithiolene complexes have interesting structures and fascinating redox properties, making them promising candidates for a number of applications, including superconductors, photonic devices, chemical sensors, and catalysts. However, not enough is known about the molecular electronic origins of these properties. Multinuclear solid-state NMR spectroscopy and first-principles calculations are used to examine the molecular and electronic structures of the redox series [Pt(tfd)(2)](z-) (tfd = S(2)C(2)(CF(3))(2); z = 0, 1, 2; the anionic species have [NEt(4)](+) countercations). Single-crystal X-ray structures for the neutral (z = 0) and the fully reduced forms (z = 2) were obtained. The two species have very similar structures but differ slightly in their intraligand bond lengths. (19)F-(195)Pt CP/CPMG and (195)Pt magic-angle spinning (MAS) NMR experiments are used to probe the diamagnetic (z = 0, 2) species, revealing large platinum chemical shielding anisotropies (CSA) with distinct CS tensor properties, despite the very similar structural features of these species. Density functional theory (DFT) calculations are used to rationalize the large platinum CSAs and CS tensor orientations of the diamagnetic species using molecular orbital (MO) analysis, and are used to explain their distinct molecular electronic structures in the context of the NMR data. The paramagnetic species (z = 1) is examined using both EPR spectroscopy and (13)C and (19)F MAS NMR spectroscopy. Platinum g-tensor components were determined by using solid-state EPR experiments. The unpaired electron spin densities at (13)C and (19)F nuclei were measured by employing variable-temperature (13)C and (19)F NMR experiments. DFT and ab initio calculations are able to qualitatively reproduce the experimentally measured g-tensor components and spin densities. The combination of experimental and theoretical data confirm localization of unpaired electron density in the pi-system of the

  6. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    Science.gov (United States)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  7. NMR a substitute for CT

    International Nuclear Information System (INIS)

    The possibility that NMR (Nuclear Magnetic Resonance) can be a substitute for CT (Computerized Tomography), is described. NMR focus on the nuclei in the atoms of certain elements, for example hydrogen

  8. 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.)

  9. NMR crystallography of polylactide

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří

    Prague : Institute of Macromolecular Chemistry AS CR, v. v. i, 2013. s. 60. ISBN 978-80-85009-77-4. [European Symposium on Polymer Spectroscopy /19./ - ESOPS19. Prague Meeting on Macromolecules /77./. 07.07.2013-11.07.2013, Prague] Institutional support: RVO:61389013 Keywords : NMR crystallography * polylactide Subject RIV: CD - Macromolecular Chemistry

  10. Soils, Pores, and NMR

    Science.gov (United States)

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

    2010-05-01

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

  11. The Protease Allergen Pen c 13 Induces Allergic Airway Inflammation and Changes in Epithelial Barrier Integrity and Function in a Murine Model*

    OpenAIRE

    Chen, Jui-Chieh; Chuang, Jiing-Guang; Su, Yu-Yi; Chiang, Bor-Luen; Lin, You-Shuei; Chow, Lu-Ping

    2011-01-01

    Fungal allergens are associated with the development of asthma, and some have been characterized as proteases. Here, we established an animal model of allergic airway inflammation in response to continuous exposure to proteolytically active Pen c 13, a major allergen secreted by Penicillium citrinum. In functional analyses, Pen c 13 exposure led to increased airway hyperresponsiveness, significant inflammatory cell infiltration, mucus overproduction, and collagen deposition in the lung, drama...

  12. Natural abundance of N-15 and C-13 in fish tissues and the use of stable isotopes as dietary protein tracers in rainbow trout and gilthead sea bream

    OpenAIRE

    Beltran, M; Fernandez-borras, J.; Medale, Francoise; Perez-sanchez, J.; Kaushik, Sadasivam; Blasco, J.

    2009-01-01

    For developing efficient diets, two sets of experiments examined whether the use and allocation of dietary protein can be traced by labelling with stable isotopes (N-15 and C-13) in two culture fish (Oncorhynchus mykiss and Sparus aurata). In the first experiment, natural abundance and tissue distribution of these isotopes were determined, by measuring the delta C-13 and delta N-15 values by isotopic ratio mass spectrometry, in fingerlings (14-17 g) adapted to diets differing in the percentag...

  13. Development of a low resolution (1)H NMR spectroscopic technique for the study of matrix mobility in fresh and freeze-thawed hen egg yolk.

    Science.gov (United States)

    Au, Carmen; Wang, Tong; Acevedo, Nuria C

    2016-08-01

    Three experiments were conducted in developing a low resolution proton nuclear magnetic resonance ((1)H NMR) spectroscopic technique to study matrix mobility in fresh and freeze-thawed gelled yolk. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was used to measure spin-spin relaxation times of proton pools representing major yolk constituents. A component identification test distinguished 3-4 pools. The least mobile pool was assigned to proteins, protein-lipid and protein-water interactions, and the most mobile to unbound water. The remaining pools were assigned to lipids, lipid-protein and lipid-water interactions. A stability test indicated that yolk had varied matrix mobility within the same sample across five days of refrigeration storage. A reproducibility test demonstrated high repeatability of fresh yolk measurements, but significant differences (p<0.05) were found within gelled yolk samples. This research determined that (1)H NMR spectroscopy, a non-destructive technique, can identify yolk components and detect changes in the matrix. PMID:26988489

  14. The automatic NMR gaussmeter

    International Nuclear Information System (INIS)

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

  15. NMR of unfolded proteins

    Indian Academy of Sciences (India)

    Amarnath Chtterjee; Ashutosh Kumar; Jeetender Chugh; Sudha Srivastava; Neel S Bhavesh; Ramakrishna V Hosur

    2005-01-01

    In the post-genomic era, as more and more genome sequences are becoming known and hectic efforts are underway to decode the information content in them, it is becoming increasingly evident that flexibility in proteins plays a crucial role in many of the biological functions. Many proteins have intrinsic disorder either wholly or in specific regions. It appears that this disorder may be important for regulatory functions of the proteins, on the one hand, and may help in directing the folding process to reach the compact native state, on the other. Nuclear magnetic resonance (NMR) has over the last two decades emerged as the sole, most powerful technique to help characterize these disordered protein systems. In this review, we first discuss the significance of disorder in proteins and then describe the recent developments in NMR methods for their characterization. A brief description of the results obtained on several disordered proteins is presented at the end.

  16. NMR, water and plants

    International Nuclear Information System (INIS)

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

  17. Spectra identification and interpretation comparing the spectral informations - the example of infrared, C13 magnetic resonance and mass spectroscopy

    International Nuclear Information System (INIS)

    A computer assisted spectra interpretation based on special comparison was developed. The search program implements three different searching strategies to be used according to the specific analytical problem: Search for a spectrum of the same substance, partial structure search and spectra identification for mixed substances. It turned out, that the success of a search program depends significantly on the used spectra collection; optimization procedures involve the information content classification for each spectral information. A combined search program is demonstrated for infrared, 13C-NMR and mass spectra. (TW)

  18. Catenanes: A molecular mechanics analysis of the (C13H26)2 Structure 13-13 D2.

    Science.gov (United States)

    Lii, Jenn-Huei; Allinger, Norman L; Hu, Ching-Han; Schaefer, Henry F

    2016-01-01

    Molecular mechanics (MM4) studies have been carried out on the catenane (C13H26)2, specifically 13-13D2. The structure obtained is in general agreement with second-order perturbation theory. More importantly, the MM4 structure allows a breakdown of the energy of the molecule into its component classical parts. This allows an understanding of why the structure is so distorted, in terms of C-C bonding and nonbonding interactions, van der Waals repulsion, C-C-C and C-C-H angle bending, torsional energies, stretch-bend, torsion-stretch, and bend-torsion-bend interactions. Clearly, the hole in 113-membered ring is too small for the other ring to fit through comfortably. There are too many atoms trying to fit into the limited space at the same time, leading to large van der Waals repulsions. The rings distort in such a way as to enlarge this available space, and lower the total energy of the molecule. While the distortions are spread around the rings, one of the nominally tetrahedral C-C-C bond angles in each ring is opened to 147.9° by MM4 (146.8° by MP2). The stability of the compound is discussed in terms of the strain energy. PMID:26511440

  19. 12C/13C and H/D vapor pressure isotope effects of fluoroform: intermolecular interactions in liquid fluoroform

    International Nuclear Information System (INIS)

    A precision cryostat of the Bigeleisen-Brooks-Ribnikar-Ishida (BBIR) type with associated vacuum systems has been constructed and the appropriate temperature/pressure measurement and control systems designed and implemented. Various improvements in the cryostat design were incorporated in order to facilitate the assembly and repair processes. A major design change involved the incorporation of a digital stand alone computer to control cryostat operations. This apparatus was used to measure the 12C/13C and H/D Vapor Pressure Isotope Effects of Fluoroform. Analysis of the measured VPIE results, in light of existing experimental data and theories, has demonstrated the need of a temperature dependent liquid force field, specifically a temperature-dependent interaction force constant between the C-H stretching motion and translational motion in the direction of the figure axis of CHF3. This result is consistent with the observed spectroscopic data and vibrational and configurational models of fluoroform dimers. The intermolecular interaction is believed to be a weak hydrogen-bond in nature

  20. 2D NMR技术在石油测井中的应用%Application of 2D NMR Techniques in Petroleum Logging

    Institute of Scientific and Technical Information of China (English)

    顾兆斌; 刘卫; 孙佃庆; 孙威

    2009-01-01

    近几年, 2D NMR技术得到迅速发展, 特别是在核磁共振测井领域. 该文将主要介绍2D NMR技术的脉冲序列、弛豫原理以及2D NMR技术在石油测井中应用. 2D NMR技术是在梯度场的作用下, 利用一系列回波时间间隔不同的CPMG脉冲进行测量, 利用二维的数学反演得到2D NMR. 2D NMR技术可以直接测量自扩散系数、弛豫时间、原油粘度、含油饱和度、可动水饱和度、孔隙度、 渗透率等地层流体性质和岩石物性参数. 从2D NMR谱上, 可以直观的区分油、气、水, 判断储层润湿性, 确定内部磁场梯度等. 2D NMR技术为识别流体类型提供了新方法.%This review paper introduces 2D NMR pulse trains frequently used in petroleum logging and their applications, as well as relevant relaxation mechanisms. In NMR logging, often a set of data is acquired at different CPMG echo spacing in the presence of constant gradient magnetic field. Two-dimensional mathematical inversion is then applied to solve the dataset, yielding two-dimensional NMR map (D-T_2). In the meanwhile, 2D NMR technique can be used to measure the property parameters of formation fluid and the petrophysics parameters directly, such as diffusion coefficient, relaxation time, crude oil viscosity, oil saturation, free water saturation, porosity, permeability and so on. The 2D NMR map can also be used to differentiate oil, gas and water, determine internal gradient field in and judge wettability of the sample. 2D NMR techniques offer powerful tools for identifying fluid type in NMR logging.

  1. NMR molecular photography

    OpenAIRE

    Khitrin, Anatoly K.; Ermakov, Vladimir L.; Fung, B M

    2002-01-01

    A procedure is described for storing a 2D pattern consisting of 32x32 = 1024 bits in a spin state of a molecular system and then retrieving the stored information as a stack of NMR spectra. The system used is a nematic liquid crystal, the protons of which act as spin clusters with strong intramolecular interactions. The technique used is a programmable multi-frequency irradiation with low amplitude. When it is applied to the liquid crystal, a large number of coherent long-lived 1H response si...

  2. Enhancement of Palmarumycin C12 and C13 Production by the Endophytic Fungus Berkleasmium sp. Dzf12 in an Aqueous-Organic Solvent System

    Directory of Open Access Journals (Sweden)

    Yan Mou

    2015-11-01

    Full Text Available The endophytic fungus Berkleasmium sp. Dzf12, isolated from Dioscorea zingiberensis, was found to produce palmarumycins C12 and C13 which possess a great variety of biological activities. Seven biocompatible water-immiscible organic solvents including n-dodecane, n-hexadecane, 1-hexadecene, liquid paraffin, dibutyl phthalate, butyl oleate and oleic acid were evaluated to improve palmarumycins C12 and C13 production in suspension culture of Berkleasmium sp. Dzf12. Among the chosen solvents both butyl oleate and liquid paraffin were the most effective to improve palmarumycins C12 and C13 production. The addition of dibutyl phthalate, butyl oleate and oleic acid to the cultures of Berkleasmium sp. Dzf12 significantly enhanced palmarumycin C12 production by adsorbing palmarumycin C12 into the organic phase. When butyl oleate was fed at 5% (v/v in medium at the beginning of fermentation (day 0, the highest palmarumycin C12 yield (191.6 mg/L was achieved, about a 34.87-fold increase in comparison with the control (5.3 mg/L. n-Dodecane, 1-hexadecene and liquid paraffin had a great influence on the production of palmarumycin C13. When liquid paraffin was added at 10% (v/v in medium on day 3 of fermentation, the palmarumycin C13 yield reached a maximum value (134.1 mg/L, which was 4.35-fold that of the control (30.8 mg/L. Application of the aqueous-organic solvent system should be a simple and efficient process strategy for enhancing palmarumycin C12 and C13 production in liquid cultures of the endophytic fungus Berkleasmium sp. Dzf12.

  3. Comparison of the Quantitative Values of C-14 and C-13 UBT to Reflect the Presence and Degree of Ongoing Helicobacter pylori Infection

    International Nuclear Information System (INIS)

    A urea breath test (UBT) using C-14 or C-13 has been developed for identifying Helicobacter (H) pylori infection on the basis of urease production with release of labeled CO2. We investigated if the C-14 and C-13 UBT have the difference to reflect the presence and degree of H. pylori infection detected by gastroduodenoscopic biopsies (GBx) in the same patients. Thirty eight patients (M:F=28:10, age 53.4±13.0 yrs) with upper gastrointestinal symptoms such as indigestion, gastric fullness or pain consecutively underwent C-14 UBT, GBx and C-13 UBT within one week before medications. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (37 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive (≥200 dpm), intermediate (50∼199 dpm) or negative (<50 dpm). For the C-13 UBT, the results were classified as positive (≥2.5) or negative (<2.5). The results of GBx with Giemsa stain were graded 0 (normal) to 4 (diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT and C-13 UBT results with GBx grade as a gold standard. The prevalence of H. pylori infection by GBx with Giemsa stain was 25/38 (65.8%). In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.0%, 92.3%, 95.8%, 91.7% and 92.1%, respectively. However, the C-13 UBT had sensitivity, specificity, PPV, NPV and accuracy of 96.0%, 84.6%, 92.3%, 91.7% and 92.1%, respectively. The more significant correlation in C-14 than C-13 UBT (r=0.948 vs r=0.819, p<0.001) was found between the value of UBT and the grade of distribution of H. pylori infection. We conclude that the diagnostic performance between C-14 and C-13 UBT to detect H. pylori infection is not significantly different, but the value of C-14 UBT more

  4. Comparison of the Quantitative Values of C-14 and C-13 UBT to Reflect the Presence and Degree of Ongoing Helicobacter pylori Infection

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seok Tae; Kim, Dong Wook; Jeong, Hwan Jeong; Sohn, Myung Hee [Chonbuk National University Medical School, Jeonju (Korea, Republic of)

    2008-06-15

    A urea breath test (UBT) using C-14 or C-13 has been developed for identifying Helicobacter (H) pylori infection on the basis of urease production with release of labeled CO{sub 2}. We investigated if the C-14 and C-13 UBT have the difference to reflect the presence and degree of H. pylori infection detected by gastroduodenoscopic biopsies (GBx) in the same patients. Thirty eight patients (M:F=28:10, age 53.4{+-}13.0 yrs) with upper gastrointestinal symptoms such as indigestion, gastric fullness or pain consecutively underwent C-14 UBT, GBx and C-13 UBT within one week before medications. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (37 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive ({>=}200 dpm), intermediate (50{approx}199 dpm) or negative (<50 dpm). For the C-13 UBT, the results were classified as positive ({>=}2.5) or negative (<2.5). The results of GBx with Giemsa stain were graded 0 (normal) to 4 (diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT and C-13 UBT results with GBx grade as a gold standard. The prevalence of H. pylori infection by GBx with Giemsa stain was 25/38 (65.8%). In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.0%, 92.3%, 95.8%, 91.7% and 92.1%, respectively. However, the C-13 UBT had sensitivity, specificity, PPV, NPV and accuracy of 96.0%, 84.6%, 92.3%, 91.7% and 92.1%, respectively. The more significant correlation in C-14 than C-13 UBT (r=0.948 vs r=0.819, p<0.001) was found between the value of UBT and the grade of distribution of H. pylori infection. We conclude that the diagnostic performance between C-14 and C-13 UBT to detect H. pylori infection is not significantly different, but the value of C-14 UBT

  5. Embedded NMR Sensor to Monitor Compressive Strength Development and Pore Size Distribution in Hydrating Concrete

    Directory of Open Access Journals (Sweden)

    Floriberto Díaz-Díaz

    2013-11-01

    Full Text Available In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30 and high (0.6 w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30. The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97 from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer.

  6. An NMR study of sodium poly(acrylate) adsorption on rutile

    International Nuclear Information System (INIS)

    Adsorption of sodium poly(acrylate) (PA) on rutile particles in aqueous dispersion was studied. Two different molecular weights of PA (2,100 and 30,000) and two different grades of rutile were used. Various pHs, ionic strengths, and PA concentrations were investigated. The main technique employed was measurement of the transverse NMR relaxation of the solvent using the CPMG pulse sequence. Other techniques used to augment these results include electroacoustics, scanning electron microscopy, and measurement of the adsorbed amount of PA by a fluorescence spectroscopy technique using the dye acridine orange. Adsorption of small ions such as Na+, K+, Cl-, and NO3- to the particle surface was found to have a significant effect on the measured transverse relaxation rate, that was dependent on the pH and the concentration of the ions. There was usually an additional effect on the relaxation due to the adsorbed PA, but only qualitative rather than quantitative information about the adsorption could be deduced. At pH 4 especially, it could be seen that the results were consistent with the common assertion that polymers adsorb in a flat conformation at low concentration, and only become looped when all of the surface sites are full. At pH 10 it was found that the relaxation rate for the longer chain PA samples fluctuated over time, indicating metastable PA conformations. There were also unusual trends in the relaxation rate for these samples, which could be due to a previously proposed small ion complexation mechanism for PA adsorption at high pH in this system. It is possible that an extensive and comprehensive study using this technique, investigating all of the relevant parameters, especially the effect of small ion adsorption, may allow a quantitative description of the adsorbed conformation. (author)

  7. Bentonite pore structure based on SAXS, chloride porosity and NMR studies

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. 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 inter-lamellar (IL) and non-inter-lamellar (non-IL) pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from MX-80 bentonite were studied with nuclear magnetic resonance (NMR) and small-angle x-ray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.7 and 1.6 g/cm3. The NMR technique was used to get information about the relative amounts of different water types in the bentonite samples by following a method similar to the one described in Ohkubo et al. (2008). The pores in the bentonite/water samples offer different conditions for water molecules. In a motion-restricted environment, the relaxation rate of water next to the layer surfaces is greater than that of the bulk water. The results were obtained using 1H NMR T1ρ relaxation time measurements using the short inter-pulse CPMG method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurement on bentonite samples was used to get information about the size distribution of the inter-lamellar distance of montmorillonite. However, it is not possible to conclude from the SAXS curve which fraction of montmorillonite contributes to the SAXS spectra, i.e. which part of the surface area can be considered as an inter-lamellar one. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results to evaluate the bentonite microstructure of MX-80 samples. Two microstructural models of bentonite, the layer model and the gel model, were used in the evaluation. In the layer model, the montmorillonite was organized in stacks having

  8. NMR spectrometers as "magnetic tongues"

    DEFF Research Database (Denmark)

    Malmendal, Anders; Amoresano, Claudia; Trotta, Roberta;

    2011-01-01

    the analyzed samples based on their chemical composition. We were able to correlate the NMR metabolomic fingerprints recorded for canned tomato samples to the sensory descriptors bitterness, sweetness, sourness, saltiness, tomato and metal taste, redness, and density, suggesting that NMR might be a very useful...

  9. 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.

  10. 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.

  11. 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...

  12. Land-use related organic matter dynamics in North Cameroon soils assessed by C-13 analysis of soil organic matter fractions

    NARCIS (Netherlands)

    Sevink, J; Obale-Ebanga, F; Meijer, HAJ

    2005-01-01

    Topsoil samples from cultivated and adjacent non-cultivated fields on three major agricultural soils in North Cameroon were fractionated into particle-size fractions that were analysed subsequently for their C and C-13 contents. The aim was to obtain further insight into the dynamics of soil organic

  13. Maximization of yield of C-13 isotope by multiphoton dissociation of Freon-22 using high average power TEA CO2 laser

    Indian Academy of Sciences (India)

    Manoj Kumar; Anant Deshpande; Chintan Gupta; A K Biswas; A K Nath

    2002-12-01

    Selective multi-photon dissociation (MPD) of Freon-22 (CF2HCl) molecules has been carried out using a TEA CO2 laser at various CO2 laser lines (9(20)-9(26)) in order to maximize the yield of C-13 isotope in the product (C2F4) at an enrichment factor of 100. The effects of laser pulse tail due to the presence of N2 in the laser mixture on the enrichment factor and yield of C-13 are investigated. It is found that the addition of a small amount of N2 is possible in the laser mixture without a significant drop in the yield at desired enrichment factor. Addition of a small amount of N2 improves the laser efficiency considerably. At a given pulse energy, a slight change in the near field intensity distribution of a laser severely affects the selectivity of C-13 isotope. The computed far-field intensity distributions of the measured near-field intensities show marked spatial variation in the focal spots that leads to a drop in selectivity. For macroscopic production of C-13 isotope a simple and novel multi-pass cavity has been designed and tested to focus the energy repeatedly keeping the optimum fluence constant at each focal spot.

  14. The C-13 Suess effect in the world surface oceans and its implications for oceanic uptake of CO2 : Analysis of observations at Bermuda

    NARCIS (Netherlands)

    Bacastow, RB; Keeling, CD; Lueker, TJ; Wahlen, M; Mook, WG

    1996-01-01

    Surface ocean water delta(13)C measurements near Bermuda are examined in an attempt to find the annual decrease caused by the addition of anthropogenic CO2 to the atmosphere. We refer to this trend as the surface ocean C-13 Suess effect. Interannual variability, which may be related to the El Nino -

  15. Constants of NMR spectra

    International Nuclear Information System (INIS)

    The NMR (nuclear magnetic resonance) spectroscopy is a method for studying matter. It has been developed in a lot of fields of physics, physical chemistry, chemistry and biology. It concerns both the solid state and the liquid state. The study in solution of synthesis organic molecules or of organic molecules of natural origin and of biological molecules is particularly stressed on but it is also possible to study inorganic molecules. The originality of this method is to give both data on each atoms of the studied structure, on the atoms sequence in this structure, on the conformation and on the related configurations. It allows to reveal the interactions between separate molecules too. It is also a precious tool for the analysis of molecular movements. The development of this method for the study of condensed phases is particularly studied nowadays and the data obtained are for a lot of fields as acute as those obtained at the liquid state. (O.M.)

  16. Membrane-bound structure and alignment of the antimicrobial {beta}-sheet peptide gramicidin S derived from angular and distance constraints by solid state 19F-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Jesus; Grage, Stephan L. [University of Jena, Department of Molecular Biology (Germany); Kondejewski, Leslie H. [University of Alberta, Protein Engineering Network of Centres of Excellence (Canada); Hodges, Robert S.; McElhaney, Ronald N. [University of Alberta, Department of Biochemistry (Canada); Ulrich, Anne S. [University of Jena, Department of Molecular Biology (Germany)

    2001-11-15

    The antimicrobial properties of the cyclic {beta}-sheet peptide gramicidin S are attributed to its destabilizing effect on lipid membranes. Here we present the membrane-bound structure and alignment of a derivative of this peptide, based on angular and distance constraints. Solid-state {sup 19}F-NMR was used to study a {sup 19}F-labelled gramicidin S analogue in dimyristoylphosphatidylcholine bilayers at a lipid:peptide ratio of 80:1 and above. Two equivalent leucine side chains were replaced by the non-natural amino acid 4F-phenylglycine, which serves as a highly sensitive reporter on the structure and dynamics of the peptide backbone. Using a modified CPMG multipulse sequence, the distance between the two {sup 19}F-labels was measured from their homonuclear dipolar coupling as 6 A, in good agreement with the known backbone structure of natural gramicidin S in solution. By analyzing the anisotropic chemical shift of the {sup 19}F-labels in macroscopically oriented membrane samples, we determined the alignment of the peptide in the bilayer and described its temperature-dependent mobility. In the gel phase, the {sup 19}F-labelled gramicidin S is aligned symmetrically with respect to the membrane normal, i.e., with its cyclic {beta}-sheet backbone lying flat in the plane of the bilayer, which is fully consistent with its amphiphilic character. Upon raising the temperature to the liquid crystalline state, a considerable narrowing of the {sup 19}F-NMR chemical shift dispersion is observed, which is attributed the onset of global rotation of the peptide and further wobbling motions. This study demonstrates the potential of the {sup 19}F nucleus to describe suitably labelled polypeptides in membranes, requiring only little material and short NMR acquisition times.

  17. Two dimensional solid state NMR

    International Nuclear Information System (INIS)

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

  18. NMR for chemists and biologists

    CERN Document Server

    Carbajo, Rodrigo J

    2013-01-01

    This book intends to be an easy and concise introduction to the field of nuclear magnetic resonance or NMR, which has revolutionized life sciences in the last twenty years. A significant part of the progress observed in scientific areas like Chemistry, Biology or Medicine can be ascribed to the development experienced by NMR in recent times. Many of the books currently available on NMR deal with the theoretical basis and some of its main applications, but they generally demand a strong background in Physics and Mathematics for a full understanding. This book is aimed to a wide scientific audie

  19. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A; McCarthy, M J

    1995-01-01

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

  20. Metabolic flux determination using carbon 13 NMR. Application to normal and tumoral cells from central nervous system

    International Nuclear Information System (INIS)

    Carbon 13 NMR constitutes a potent tool to study cellular metabolism by the use of 13C enriched substrates. Analyzes of 13C NMR spectra recorded from acidic cell extracts lead to the evaluation of specific enrichment of various metabolites. On the other hand, the measure of homonuclear 13C-13C spin coupling gives information on the different isotopomers for a given molecule. Mathematical models were different isotopomers for a given molecule. Mathematical models were developed to interpret the NMR data in terms of metabolic fluxes through the metabolic network of interest. Various models established in our laboratory are presented. These models were applied to metabolic studies of cultured central nervous system cells as rat cerebellar astrocytes and granule cells, and the C6 glioma cell line. (authors). 17 refs., 3 figs., 2 tabs

  1. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    Science.gov (United States)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    . The Hartmann-Hahn condition can be expressed as γHB1H = γCB1C, where γH and γC are the gyromagnetic ratios of protons and carbons, whereas B1H and B1C are the 1H and 13C radio-frequency (r.f.) fields applied to the nuclei. The Hartmann-Hahn condition is affected by the H-C dipolar interaction strength (Stejskal & Memory, 1994). All the factors affecting dipolar interactions may mismatch the Hartmann-Hahn condition and prevent a quantitative representation of the NOM chemical composition (Conte et al., 2004). It has been reported that under low speed MAS conditions, broad matching profiles are centered around the Hartmann-Hahn condition....... With increasing spinning speed the Hartmann-Hahn matching profiles break down in a series of narrow matching bands separated by the rotor frequency (Stejskal & Memory, 1994). In order to account for the instability of the Hartmann-Hahn condition at higher rotor spin rates (>10 kHz), variable amplitude cross-polarization techniques (RAMP-CP) have been developed (Metz et al., 1996). So far, to our knowledge, the prevailing way used to obtain quantitative 13C-CPMAS NMR results was to optimize the 1H and 13C spin lock r.f. fields on simple standard systems such as glycine and to use those r.f. field values to run experiments on unknown organic samples. The aim of the present study was to experimentally evidence that the stability of the Hartmann-Hahn condition was different for different samples with a known structure. Moreover, Hartmann-Hahn profiles of four different humic acids (HAs) were also provided in order to show that the 1H/13C r.f. spin lock field strength must also be tested on the HAs prior to a quantitative evaluation of their 13C-CPMAS NMR spectra. Baldock, J.A., Oades, J.M., Nelson, P.N., Skene, T.M., Golchin, A. & Clarke, P., 1997. Assessing the extent of decomposition of natural organic materials using solid-state C-13 NMR spectroscopy. Australian Journal of Soil Research, 35, 1061-1083. Conte, P., Piccolo, A

  2. Integrative NMR for biomolecular research.

    Science.gov (United States)

    Lee, Woonghee; Cornilescu, Gabriel; Dashti, Hesam; Eghbalnia, Hamid R; Tonelli, Marco; Westler, William M; Butcher, Samuel E; Henzler-Wildman, Katherine A; Markley, John L

    2016-04-01

    NMR spectroscopy is a powerful technique for determining structural and functional features of biomolecules in physiological solution as well as for observing their intermolecular interactions in real-time. However, complex steps associated with its practice have made the approach daunting for non-specialists. We introduce an NMR platform that makes biomolecular NMR spectroscopy much more accessible by integrating tools, databases, web services, and video tutorials that can be launched by simple installation of NMRFAM software packages or using a cross-platform virtual machine that can be run on any standard laptop or desktop computer. The software package can be downloaded freely from the NMRFAM software download page ( http://pine.nmrfam.wisc.edu/download_packages.html ), and detailed instructions are available from the Integrative NMR Video Tutorial page ( http://pine.nmrfam.wisc.edu/integrative.html ). PMID:27023095

  3. Optical pumping and xenon NMR

    Energy Technology Data Exchange (ETDEWEB)

    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 [sup 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 [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  4. Optical pumping and xenon NMR

    Energy Technology Data Exchange (ETDEWEB)

    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 {sup 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 {sup 131}Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  5. Optical pumping and xenon NMR

    International Nuclear Information System (INIS)

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

  6. Variablility of stable isotope signatures (delta C-13 and delta N-15) in two spider crab populations (Maja brachydactyla) in Western Europe

    OpenAIRE

    Bodin, N.; Le Loc'H, François; Hily, C.; Caisey, X.; Latrouite, D.; Le Guellec, A. M.

    2007-01-01

    The ontogenic variations of nitrogen and carbon stable isotopic signatures (delta N-15 and delta C-13) were investigated in two spider crab (Maja brachydactyla) populations inhabiting in different biotopes of Western Europe. The Iroise Sea population is localized in Western Brittany and characterized by a seasonal migration occurring on a large bathymetric and habitat gradient while the Seine Bay population, in the Eastern English Channel, remains in a more homogeneous environment during its ...

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

    International Nuclear Information System (INIS)

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

  8. NMR Dynamic Studies in Living Systems

    Institute of Scientific and Technical Information of China (English)

    闫永彬; 范明杰; 罗雪春; 张日清

    2002-01-01

    Nuclear magnetic resonance (NMR) can noninvasively monitor the intracellular concentrations and kinetic properties of numerous inorganic and organic compounds. These characteristics have made NMR a useful tool for dynamic studies of living systems. Applications of NMR to living systems have successfully extended to many areas, including studies of metabolic regulation, ion transport, and intracellular reaction rates in vivo. The major purpose of this review is to summarize the results that can be obtained by modern NMR techniques in living systems. With the advances of new techniques, NMR measurements of various nuclides have been performed for specific physiological purposes. Although some technical problems still remain and there are still discrepancies between NMR and traditional biochemical results, the abundant and unique information obtained from NMR spectra suggests that NMR will be more extensively applied in future studies of living systems. The fast development of these new techniques is providing many new NMR applications in living systems, as well as in structural biology.

  9. A Quantitative NMR Analysis of Phosphorus in Carbonaceous and Ordinary Chondrites

    Science.gov (United States)

    Pasek, M. A.; Smith, V. D.; Lauretta, D. S.

    2004-01-01

    Phosphorus is important in a number of biochemical molecules, from DNA to ATP. Early life may have depended on meteorites as a primary source of phosphorus as simple dissolution of crustal apatite may not produce the necessary concentration of phosphate. Phosphorus is found in several mineral phases in meteorites. Apatite and other Ca- and Mg phosphate minerals tend to be the dominant phosphorus reservoir in stony meteorites, whereas in more iron-rich or reduced meteorites, the phosphide minerals schreibersite, (Fe, Ni)3P, and perryite, (Ni, Fe)5(Si, P)2 are dominant. However, in CM chondrites that have experienced significant aqueous alteration, phosphorus has been detected in more exotic molecules. A series of phosphonic acids including methyl-, ethyl-, propyl- and butyl- phosphonic acids were observed by GC-MS in Murchison. Phosphorian sulfides are in Murchison and Murray. NMR spectrometry is capable of detecting multiple substances with one experiment, is non-destructive, and potentially quantitative, as discussed below. Despite these advantages, NMR spectrometry is infrequently applied to meteoritic studies due in large part to a lack of applicability to many compounds and the relatively high limit of detection requirements. Carbon-13 solid-state NMR has been applied to macromolecular carbon in Murchison. P-31 NMR has many advantages over aqueous carbon-13 NMR spectrometry. P-31 is the only isotope of phosphorus, and P-31 gives a signal approximately twice as strong as C-13. These two factors together with the relative abundances of carbon and phosphorus imply that phosphorus should give a signal approximately 20 as strong as carbon in a given sample. A discussion on the preparation of the quantitative standard and NMR studies are presented

  10. NMR and dynamics of biopolymers

    International Nuclear Information System (INIS)

    Several basic experimental analytical NMR techniques that are frequently used for the qualitative and quantitative analysis of dynamic and exchange processes, focusing on proteins systems, are described: chemical exchange (slow exchange, fast exchange, intermediate exchange), heteronuclear relaxation measurements (relaxation parameters, strategy of relaxation data analysis, experimental results and examples, motional model interpretation of relaxation data, homonuclear relaxation); slow large-scale exchange and hydrogen-deuterium exchange are also studied: mechanisms of hydrogen exchange in a native protein, methods for measuring amide exchange rates by NMR, interpretation of amide exchange rates. 9 fig., 3 tab., 56 ref

  11. Two-dimensional NMR spectrometry

    International Nuclear Information System (INIS)

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

  12. Advanced NMR characterization of zeolite catalysts

    Science.gov (United States)

    Welsh, L. B.

    1985-04-01

    The program discussed in this report is a two-year two-phase joint UOP-University of Illinois study of the application of improved high resolution solid state nuclear magnetic resonance (NMR) techniques to the characterization of zeolite catalysts. During the first phase of this program very pure, and in some cases isotopically enriched faujasites will be prepared and studied by magic angle sample spinning NMR (MASS NMR) and variable engine sample spinning NMR (VASS NMR) on 500 and 360 MHz (proton frequency) NMR spectrometers. The NMR techniques that will be emphasized are the measurement and analysis of the (17)O NMR properties, (27)Al NMR intensity quantitation, and (27)Al and (29)Si NMR relaxation rates. During the second phase of this program these NMR techniques will be used to study the effects of impurity concentration, dealumination treatments and cation exchange on the NMR properties of faujasites. The initial emphasis of this program during Phase I is on the preparation and measurement of the NMR properties of (17)O enriched Na-Y faujasties.

  13. Accelerator mass spectrometry measurements of the C-13(n,gamma)C-14 and N-14(n,p)C-14 cross sections

    OpenAIRE

    Wallner, A.; Bichler, M.; Buczak, K.; Dillmann, I.; Kaeppeler, F.; A. Karakas; Lederer, C.; Lugaro, M.; Mair, K.; A.Mengoni; Schaetzel, G.; P. Steier; Trautvetter, H. P.

    2016-01-01

    The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the C-13(n,gamma)C-14 and the N-14(n,p)C-14 cross sections, which act as a neutron poison in s-process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT = 25 keV, and also at higher energies between En = 123 an...

  14. Partitioning of ocean and land uptake of CO2 as inferred by delta C-13 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network

    Science.gov (United States)

    Ciais, Philippe; Tans, Pieter P.; White, James W. C.; Trolier, Michael; Francey, Roger J.; Berry, Joe A.; Randall, David R.; Sellers, Piers J.; Collatz, James G.; Schimel, David S.

    1995-01-01

    Using delta C-13 measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta C-13 measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. We perform an inverse deconvolution of both CO2 and delta C-13 observations, using a two-dimensional model of atmospheric transport. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the simple biosphere (SiB) model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(exp 15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.2 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 deg N absorbed 2.7 GTC. The equatorial oceans between 10 deg S and 10 deg N were a net source to the atmosphere of 0.9 GTC. We obtained a sink of 1.6 GTC in southern ocean gyres south of 20 deg S, although the deconvolution is poorly constrained by sparse data coverage at high southern latitudes. The seasonal uptake of CO2 in the northern gyres appears to be correlated with a bloom of phytoplankton in surface waters. On land, northern temperate and boreal ecosystems between 35 deg N and 65 deg N were found to be a major sink of CO2 in 1992, as large as 3.5 GTC. Northern tropical ecosystems (equator-30 deg N) appear to be a net

  15. Radiofrequency and magnet technology in medical NMR

    International Nuclear Information System (INIS)

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

  16. 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...

  17. 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,

  18. Cancer metastasis detected by NMR

    International Nuclear Information System (INIS)

    A narrow NMR line originating from the plasma membrane of a cancer cell is unexpected. The behaviour of these lines is explained in terms of fundamental physics and chemistry. There is biochemical evidence to support the presence of neutral lipid domains in the plasma membrane. T2 relaxation and clinical implications are briefly discussed

  19. Transmission of Electronic Substituent Effects across the 1,12-Dicarba-doso-dodecaborane Cage: A Computational Study Based on Structural Variation, Atomic Charges, and C-13 NMR Chemical Shifts

    Czech Academy of Sciences Publication Activity Database

    Campanelli, A.R.; Domenicano, A.; Hnyk, Drahomír

    2015-01-01

    Roč. 119, č. 1 (2015), s. 205-214. ISSN 1089-5639 R&D Projects: GA ČR GAP208/10/2269 Institutional support: RVO:61388980 Keywords : MONOSUBSTITUTED BENZENE RINGS * 4-SUBSTITUTED BIPHENYLS * 3-DIMENSIONAL AROMATICITY * CARBORANES * DERIVATIVES Subject RIV: CA - Inorganic Chemistry Impact factor: 2.693, year: 2014

  20. First stars IX -Mixing in extremely metal-poor giants. Variation of the 12C/13C, [Na/Mg] and [Al/Mg] ratios

    CERN Document Server

    Spite, M; Hill, V; Spite, F; François, P; Plez, B; Bonifacio, P; Molaro, P; Depagne, E; Andersen, J; Barbuy, B; Beers, T C; Nordström, B; Primas, F

    2006-01-01

    Extremely metal-poor (EMP) stars preserve a fossil record of the composition of the ISM when the Galaxy formed. It is crucial, however, to verify whether internal mixing has modified their surface. We aim to understand the CNO abundance variations found in some, but not all EMP field giants analysed earlier. Mixing beyond the first dredge-up of standard models is required, and its origin needs clarification.The 12C/13C ratio is the most robust diagnostic of deep mixing, because it is insensitive to the adopted stellar parameters and should be uniformly high in near-primordial gas. We have measured 12C and 13C abundances in 35 EMP giants from high-quality VLT/UVES spectra. Correlations with other abundance data are used to study the depth of mixing.The 12C/13C ratio is found to correlate with [C/Fe] (and Li/H), and clearly anti-correlate with [N/Fe]. Evidence for such deep mixing is observed in giants above log L/Lsolar = 2.6, brighter than in less metal-poor stars, but matching the bump in the luminosity func...

  1. The circumstellar shell of the post-AGB star HD 56126 the $^{12}C ^{12}C \\/ ^{12}C ^{13}C$isotope ratio and $^{12}C ^{16}O$ column density

    CERN Document Server

    Bakker, E J; Lambert, Eric J. Bakker & David L.

    1998-01-01

    We have made the first detection of circumstellar absorption lines of the 12C13C (Phillips) system 1-0 band and the 12C16O first-overtone 2-0 band in the spectrum of the post-AGB star HD56126 (IRAS07134+1005). The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C12C/12C13C=36+-13, 12C16O/(12C12C+12C13C)=606+-230, and 12C16O/(12C14N+13C14N)=475+-175. The isotopic exchange reaction for 12C12C is too slow to significantly alter the 12C12C/12C13C ratio and the 12C12C to 12C13C ratio a good measure of half the carbon isotope ratio: 12C/13C=2 X 12C12C/12C13C=72+-26. A fit of the 12C12C excitation model of van Dishoeck & Black (1982) to the relative population distribution of 12C12C yields n sigma / I = 3.3 +- 1.0 X 1e-14. At r=1e16cm this translates in n=1.7e7cm-3 and dM/dt=2.5e-4Msol/year.

  2. NMR Studies of Inclusion Compounds

    OpenAIRE

    Nikkhou Aski, Sahar

    2008-01-01

    This thesis presents the application of some of the NMR methods in studying host-guest complexes, mainly in solution. The general focus of the work is on investigating the reorientational dynamics of some small molecules that are bound inside cavities of larger moieties. In the current work, these moieties belong to two groups: cryptophanes and cyclodextrins. Depending on the structure of the cavities, properties of the guest molecules and the formed complexes vary. Chloroform and dichloromet...

  3. Measurement of deformations by NMR

    Science.gov (United States)

    Bytchenkoff, Dimitri; Rodts, Stéphane

    2015-12-01

    Two NMR data acquisition protocols together with corresponding data processing algorithms for locating macroscopic objects, measuring distances between them or monitoring their displacements or deformations with microscopic precision are presented and discussed. The performance of the methods is demonstrated by applying them to the measurement of deformations of a freely supported beam under loading. We believe that our methods will find their applications in mechanics, civil engineering and medicine.

  4. The relationship between delta C-13 of organic matter and (CO2(aq)) in ocean surface water - Data from the JGOFS site in the northeast Atlantic Ocean and a model. [Joint Global Ocean Flux Study

    Science.gov (United States)

    Rau, G. H.; Takahashi, T.; Des Marais, D. J.; Repeta, D. J.; Martin, J. H.

    1992-01-01

    Consistent with the hypothesis that plankton delta C-14 and (CO2(aq)) are inversely related, increases in both sinking and suspended particulate organic matter (POM) delta C-13 detected by the Joint Global Ocean Flux Study (JGOFS) were highly negatively correlated with mixed-layer (CO2(aq)). A model of plant delta C-13 by Farquhar et al. (1982) is adapted to show that under a constant phytoplankton demand for CO2 an inverse nonlinear suspended POM delta C-13 response to ambient (CO2(aq)) is expected. Differences between predicted and observed suspended POM delta C-13 vs. (CO2(aq)) trends and among observed relationships can be reconciled if biological CO2 demand is allowed to vary.

  5. Mixed-time parallel evolution in multiple quantum NMR experiments: sensitivity and resolution enhancement in heteronuclear NMR

    International Nuclear Information System (INIS)

    A new strategy is demonstrated that simultaneously enhances sensitivity and resolution in three- or higher-dimensional heteronuclear multiple quantum NMR experiments. The approach, referred to as mixed-time parallel evolution (MT-PARE), utilizes evolution of chemical shifts of the spins participating in the multiple quantum coherence in parallel, thereby reducing signal losses relative to sequential evolution. The signal in a given PARE dimension, t1, is of a non-decaying constant-time nature for a duration that depends on the length of t2, and vice versa, prior to the onset of conventional exponential decay. Line shape simulations for the 1H-15N PARE indicate that this strategy significantly enhances both sensitivity and resolution in the indirect 1H dimension, and that the unusual signal decay profile results in acceptable line shapes. Incorporation of the MT-PARE approach into a 3D HMQC-NOESY experiment for measurement of HN-HN NOEs in KcsA in SDS micelles at 50oC was found to increase the experimental sensitivity by a factor of 1.7±0.3 with a concomitant resolution increase in the indirectly detected 1H dimension. The method is also demonstrated for a situation in which homonuclear 13C-13C decoupling is required while measuring weak H3'-2'OH NOEs in an RNA oligomer

  6. RECENT PROGRESS IN BIOMOLECULAR NMR

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Structural genomics and proteomics were born from the understanding that functions of a protein are dictated by its 3D structure and dynamics. To understand protein functions on a genomic scale, we must know protein structures on a genomic scale. High resolution NMR can be used for this purpose. Traditional multidimensional NMR structure determination protocols become ineffective for structural genomics since to obtain a structure of a small protein of 15kD requires many months of painstaking spectral analysis and modeling. Recent advances in magnet and probe technology and in experimental methods have expanded the range of proteins amenable to structure determination and make the large scale structure determination possible. These advances are (1) effective expression systems for protein production, (2) introduction of cryoprobe, (3) structure determination with the use of the minimal amount of structural restraints obtained from the chemical shifts, residual dipolar couplings, NOEs, and computer modeling. In this talk,Iwill briefly outline these developments and related works done in our NMR lab.

  7. NMR-Based Milk Metabolomics

    Directory of Open Access Journals (Sweden)

    Hanne C. Bertram

    2013-04-01

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

  8. NMR-Based Milk Metabolomics.

    Science.gov (United States)

    Sundekilde, Ulrik K; Larsen, Lotte B; Bertram, Hanne C

    2013-01-01

    Milk is a key component in infant nutrition worldwide and, in the Western parts of the world, also in adult nutrition. Milk of bovine origin is both consumed fresh and processed into a variety of dairy products including cheese, fermented milk products, and infant formula. The nutritional quality and processing capabilities of bovine milk is closely associated to milk composition. Metabolomics is ideal in the study of the low-molecular-weight compounds in milk, and this review focuses on the recent nuclear magnetic resonance (NMR)-based metabolomics trends in milk research, including applications linking the milk metabolite profiling with nutritional aspects, and applications which aim to link the milk metabolite profile to various technological qualities of milk. The metabolite profiling studies encompass the identification of novel metabolites, which potentially can be used as biomarkers or as bioactive compounds. Furthermore, metabolomics applications elucidating how the differential regulated genes affects milk composition are also reported. This review will highlight the recent advances in NMR-based metabolomics on milk, as well as give a brief summary of when NMR spectroscopy can be useful for gaining a better understanding of how milk composition is linked to nutritional or quality traits. PMID:24957988

  9. Structural proteomics by NMR spectroscopy.

    Science.gov (United States)

    Shin, Joon; Lee, Woonghee; Lee, Weontae

    2008-08-01

    Structural proteomics is one of the powerful research areas in the postgenomic era, elucidating structure-function relationships of uncharacterized gene products based on the 3D protein structure. It proposes biochemical and cellular functions of unannotated proteins and thereby identifies potential drug design and protein engineering targets. Recently, a number of pioneering groups in structural proteomics research have achieved proof of structural proteomic theory by predicting the 3D structures of hypothetical proteins that successfully identified the biological functions of those proteins. The pioneering groups made use of a number of techniques, including NMR spectroscopy, which has been applied successfully to structural proteomics studies over the past 10 years. In addition, advances in hardware design, data acquisition methods, sample preparation and automation of data analysis have been developed and successfully applied to high-throughput structure determination techniques. These efforts ensure that NMR spectroscopy will become an important methodology for performing structural proteomics research on a genomic scale. NMR-based structural proteomics together with x-ray crystallography will provide a comprehensive structural database to predict the basic biological functions of hypothetical proteins identified by the genome projects. PMID:18761469

  10. C-14 dating and C-13/C-12 isotopic ratio in soils covered by natural vegetation of cerrado-floresta ecosystem at Humaita (AM)/Brazil

    International Nuclear Information System (INIS)

    The most recent evidences show that in the Amazon region significant climatic changes occurred in the Quaternary, with emphasis to the dry periods during the Pleistocene and increased precipitation in the Holocene. In this region are found areas with characteristics of cerrado, surrounded by tropical rain forest. The evaluations of soil, vegetation and climate interactions for the formation of these areas are important. Carbon isotopes (12 C, 13 C, 14 C) have been applied in soil organic matter (SOM) of Humaita region, southern Amazon, to evaluate changes in vegetation communities during the Holocene. Isotopic composition of SOM in the deeper part of the soil profiles, shows that probably in the early Holocene the forest has been in the area today occupied by the cerrado vegetation. The results of SOM in the shallow part of soil profiles characterize perfectly the three types of actual vegetation communities. (author)

  11. C-12/C-13 and O-16/O-18 ratios in the atmosphere of Venus from high-resolution 10-micron spectroscopy

    International Nuclear Information System (INIS)

    High-resolution observations of the thermal emission spectrum of Venus have been recorded in the 10.5-micron region, and these have led to the detection of several lines from the nu(3) - nu(1) bands of C-13O2 and C-12O-16O-18, as well as from the weak nu(3)+nu(2) - nu(1)+nu(2) band of C-12O2. The results obtained characterize the cloud top levels of Venus' atmosphere, at about 66 km; the derived ratios should be able to represent global values on Venus. These determinations are in agreement with in situ Pioneer Venus and Venera atmospheric composition measurements. It is demonstrated that important isotopic ratios are obtainable with ground-based spectroscopy. 26 references

  12. Asymmetric Aminohydroxylation Synthesis of Paclitaxel Side Chain Precursor%不对称氨羟化反应合成紫杉醇C13片段

    Institute of Scientific and Technical Information of China (English)

    陈雷; 孙晓莉; 匡永清; 张生勇

    2005-01-01

    用反式肉桂酸异丙酯为原料,N-溴代苯甲酰胺为助氧化供氮试剂,分别在配体3、4存在下进行锇催化的不对称氨羟化反应,一步制得抗癌药紫杉醇的C13片段N-苯甲酰基-(2R,3S)-3-苯基异丝氨酸异丙酯,收率分别为41.2%和43.6%,对映体过量(ee)均为97%.

  13. Spatio-temporal isotopic signatures (delta C-13 and delta N-15) reveal that two sympatric West African mullet species do not feed on the same basal production sources

    OpenAIRE

    Le Loc'H, François; Durand, Jean-Dominique; Diop, K.; Panfili, Jacques

    2015-01-01

    Potential trophic competition between two sympatric mullet species, Mugil cephalus and Mugil curema, was explored in the hypersaline estuary of the Saloum Delta (Senegal) using C-13 and N-15 composition of muscle tissues. Between species, N-15 compositions were similar, suggesting a similar trophic level, while the difference in C-13 compositions indicated that these species did not feed from exactly the same basal production sources or at least not in the same proportions. This result provid...

  14. Rapid solid-state NMR of deuterated proteins by interleaved cross-polarization from 1H and 2H nuclei

    Science.gov (United States)

    Bjerring, Morten; Paaske, Berit; Oschkinat, Hartmut; Akbey, Ümit; Nielsen, Niels Chr.

    2012-01-01

    We present a novel sampling strategy, interleaving acquisition of multiple NMR spectra by exploiting initial polarization subsequently from 1H and 2H spins, taking advantage of their different T1 relaxation times. Different 1H- and 2H-polarization based spectra are in this way simultaneously recorded improving either information content or sensitivity by adding spectra. The so-called Relaxation-optimized Acquisition of Proton Interleaved with Deuterium (RAPID) 1H → 13C/ 2H → 13C CP/MAS multiple-acquisition method is demonstrated by 1D and 2D experiments using a uniformly 2H, 15N, 13C-labeled α-spectrin SH3 domain sample with all or 30% back-exchanged labile 2H to 1H. It is demonstrated how 1D 13C CP/MAS or 2D 13C- 13C correlation spectra initialized with polarization from either 1H or 2H may be recorded simultaneously with flexibility to be added or used individually for spectral editing. It is also shown how 2D 13C- 13C correlation spectra may be recorded interleaved with 2H- 13C correlation spectra to obtain 13C- 13C correlations along with information about dynamics from 2H sideband patterns.

  15. The Circumstellar Shell of the Post-Asymptotic Giant Branch Star HD 56126: 12C12C/12C13C Isotope Ratio and 12C16O Column Density

    Science.gov (United States)

    Bakker, Eric J.; Lambert, David L.

    1998-11-01

    We have made the first detection of circumstellar absorption lines of the 12C13C A 1Πu-X 1Σ+g (Phillips) system 1-0 band and the 12C16O X 1Σ+ first-overtone 2-0 band in the spectrum of the post-AGB star HD 56126 (IRAS 07134+1005). All current detections of circumstellar molecular absorption lines toward HD 56126 (12C2, 12C13C, 12C14N, 13C14N, and 12C16O) yield the same heliocentric velocity of VCSE = 77.6 +/- 0.4 km s-1. The 12C2, 12C13C, and 12C16O lines give rotational temperatures and integrated column densities of Trot = 328 +/- 37 K, log Nint = 15.34 +/- 0.10 cm-2, Trot = 256 +/- 30 K, log Nint = 13.79 +/- 0.12 cm-2, and Trot = 51 +/- 37 K, log Nint = 18.12 +/- 0.13 cm-2, respectively. The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C2/12C13C = 36 +/- 13 and 12C16O/(12C2 + 12C13C) = 606 +/- 230. Combined with data from a previous paper, we find relative column densities of 12C16O/(12C14N + 13C14N) = 475 +/- 175 and 12C14N/13C14N = 38 +/- 2. Under chemical equilibrium conditions, 12C13C is formed twice as easily as 12C2. The isotopic exchange reaction for 12C2 is too slow to significantly alter the 12C2/12C13C ratio, and the 12C2 to 12C13C ratio is a good measure of half the carbon isotope ratio: 12C/13C = 2 × 12C2/12C13C = 72 +/- 26. This is in agreement with our prediction that the isotopic exchange reaction for 12C14N is efficient and our observation in Paper III of 12C14N/13C14N = 38 +/- 2. A fit of the C2 excitation model of van Dishoeck & Black to the relative population distribution of C2 yields nc σ/I = 3.3 +/- 1.0 × 10-14. At r ~= 1016 cm, this translates into nc = 1.7 × 107 cm-3 and Ṁ~=2.5×10-4 M⊙ yr-1.

  16. Quality assessment of protein NMR structures

    OpenAIRE

    Rosato A.; Montelione G.T.; Tejero R.

    2013-01-01

    Biomolecular NMR structures are now routinely used in biology, chemistry, and bioinformatics. Methods and metrics for assessing the accuracy and precision of protein NMR structures are beginning to be standardized across the biological NMR community. These include both knowledge-based assessment metrics, parameterized from the database of protein structures, and model versus data assessment metrics. On line servers are available that provide comprehensive protein structure quality assessment ...

  17. NMR INVESTIGATIONS OF HYDROGENATED AMORPHOUS SILICON

    OpenAIRE

    J. Reimer

    1981-01-01

    A review is presented of the N.M.R. (Nuclear Magnetic Resonance) studies to date of hydrogenated amorphous silicon-hydrogen films. Structural features of proton N.M.R. lineshapes, dynamics of hydrogen containing defect sites, and the promise of quantitative determinations of local silicon-hydrogen bonding environments are discussed in detail. Finally, some comments are given on future directions for N.M.R. studies of hydrogenated thin films.

  18. 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...

  19. NMR studies of isotopically labeled RNA

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-01

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

  20. Ligand-receptor Interactions by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Novak. P.

    2008-04-01

    Full Text Available Today NMR spectroscopy is a method of choice for elucidation of interactions between biomolecules and the potential ligands. Knowledge on these interactions is an essential prerequisite for the rational drug design. The most important contribution of NMR to drug design a few years ago was the 3D structure determination of proteins. Besides delivering the 3D structures of the free proteins as a raw material for the modeling studies on ligand binding, NMR can directly yield valuable experimental data on the biologically important protein-ligand complexes. In addition to X-ray diffraction, NMR spectroscopy can provide information on the internal protein dynamics ordynamics of intermolecular interactions. Changes in NMR parameters allow us to detect ("SAR by NMR" and quantitatively determine binding affinities (titration, diffusion NMR experiments, etc. of potential ligands. Also, it is possible to determine the binding site and conformations of ligands, receptors and receptor-ligand complexes with the help of NMR methods such as tr-NOESY. Epitopes or functional groups responsible for binding of ligands to the receptor can be identified by employing STD or WaterLOGSY experiments. In this review are described some of the most frequent NMR methods for the characterization of the interactions between biomolecules and ligands, together with their advantages and disadvantages.

  1. NMR exposure sensitizes tumor cells to apoptosis.

    Science.gov (United States)

    Ghibelli, L; Cerella, C; Cordisco, S; Clavarino, G; Marazzi, S; De Nicola, M; Nuccitelli, S; D'Alessio, M; Magrini, A; Bergamaschi, A; Guerrisi, V; Porfiri, L M

    2006-03-01

    NMR technology has dramatically contributed to the revolution of image diagnostic. NMR apparatuses use combinations of microwaves over a homogeneous strong (1 Tesla) static magnetic field. We had previously shown that low intensity (0.3-66 mT) static magnetic fields deeply affect apoptosis in a Ca2+ dependent fashion (Fanelli et al., 1999 FASEBJ., 13;95-102). The rationale of the present study is to examine whether exposure to the static magnetic fields of NMR can affect apoptosis induced on reporter tumor cells of haematopoietic origin. The impressive result was the strong increase (1.8-2.5 fold) of damage-induced apoptosis by NMR. This potentiation is due to cytosolic Ca2+ overload consequent to NMR-promoted Ca2+ influx, since it is prevented by intracellular (BAPTA-AM) and extracellular (EGTA) Ca2+ chelation or by inhibition of plasma membrane L-type Ca2+ channels. Three-days follow up of treated cultures shows that NMR decrease long term cell survival, thus increasing the efficiency of cytocidal treatments. Importantly, mononuclear white blood cells are not sensitised to apoptosis by NMR, showing that NMR may increase the differential cytotoxicity of antitumor drugs on tumor vs normal cells. This strong, differential potentiating effect of NMR on tumor cell apoptosis may have important implications, being in fact a possible adjuvant for antitumor therapies. PMID:16528477

  2. Spin-Exchange Pumped NMR Gyros

    CERN Document Server

    Walker, Thad G

    2016-01-01

    We present the basic theory governing spin-exchange pumped NMR gyros. We review the basic physics of spin-exchange collisions and relaxation as they pertain to precision NMR. We present a simple model of operation as an NMR oscillator and use it to analyze the dynamic response and noise properties of the oscillator. We discuss the primary systematic errors (differential alkali fields, quadrupole shifts, and offset drifts) that limit the bias stability, and discuss methods to minimize them. We give with a brief overview of a practical implementation and performance of an NMR gyro built by Northrop-Grumman Corporation, and conclude with some comments about future prospects.

  3. Advance reservoir evaluation by using NMR logging

    International Nuclear Information System (INIS)

    Based on brief explanation of the measurement principle for nuclear magnetic resonance (NMR) logging, this paper illustrates the importance of NMR logging in reservoir evaluation through typical case examples. These case examples include: Reservoir characterization and productivity evaluation by using NMR logging, determination of reservoir porosity in complex lithology, identification of oil, water and gas zones under complex reservoir conditions where resistivity log data give poor indication, guiding the implementation of completion and drilling programs, etc. Excellent application results indicate that NMR logging has its special features and advantages in comparison with conventional logging techniques. It is a very practical and very promising logging technology

  4. NMR characterization of pituitary tumors

    International Nuclear Information System (INIS)

    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

  5. NMR investigation of Ag nanoparticles

    Science.gov (United States)

    Son, Kwanghyo; Jang, Zeehoon

    2013-01-01

    109Ag nuclear magnetic resonance (NMR) and relaxation measurements have been performed on two powder samples of Ag nanoparticles with average sizes of 20 nm and 80 nm. The measurements have been done in an external field of 9.4 T and in the temperature range 10 K Knight shift ( K) and the nuclear spin-lattice relaxation rate (1/ T 1) are observed to be almost identical to the values reported for the bulk Ag metal, whereby the Korringa ratio R(= K 2 T 1 T/S) is found to be 2.0 for both samples in the investigated temperature range.

  6. 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.

  7. An isotope approach based on C-13 pulse-chase labelling vs. the root trenching method to separate heterotrophic and autotrophic respiration in cultivated peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, C.; Pitkamaki, A. S.; Tavi, N. M.; Koponen, H. T.; Martikainen, P. J. [Univ.of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], e-mail: christina.biasi@uef.fi

    2012-11-01

    We tested an isotope method based on C-13 pulse-chase labelling for determining the fractional contribution of soil microbial respiration to overall soil respiration in an organic soil (cutaway peatland, eastern Finland), cultivated with the bioenergy crop, reed canary grass. The plants were exposed to CO{sub 2}-13 for five hours and the label was thereafter determined in CO{sub 2} derived from the soil-root system. A two-pool isotope mixing model was used to separate sources of respiration. The isotopic approach showed that a minimum of 50% of the total CO{sub 2} originated from soil-microbial respiration. Even though the method uses undisturbed soil-plant systems, it has limitations concerning the experimental determination of the true isotopic signal of all components contributing to autotrophic respiration. A trenching experiment which was comparatively conducted resulted in a 71% fractional contribution of soil-microbial respiration. This value was likely overestimated. Further studies are needed to evaluate critically the output from these two partitioning approaches. (orig.)

  8. Carbon-rich presolar grains from massive stars. Subsolar 12C/13C and 14N/15N ratios and the mystery of 15N

    CERN Document Server

    Pignatari, M; Hoppe, P; Jordan, C J; Gibson, B K; Trappitsch, R; Herwig, F; Fryer, C; Hirschi, R; Timmes, F X

    2015-01-01

    Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C, and low-density graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing 12C/13C and 14N/15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the SN shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the pu...

  9. 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.

  10. NMR spectra of phosphorus 17O esters

    International Nuclear Information System (INIS)

    By the 17O NMR method the authors investigated methyl, ethyl, isopropyl, tert-butyl, and phenyl ethylene phosphites; methyl, ethyl, and isopropyl trimethylene phosphites; and methyl, ethyl, isopropyl, and tert-butyl o-phenylene phosphites. They also determined the 13C and 31P NMR spectra of these compounds

  11. 2D NMR studies of biomolecules

    International Nuclear Information System (INIS)

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

  12. NMR Spectroscopy and Its Value: A Primer

    Science.gov (United States)

    Veeraraghavan, Sudha

    2008-01-01

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

  13. An Inversion Recovery NMR Kinetics Experiment

    Science.gov (United States)

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

    2011-01-01

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

  14. 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…

  15. Early history of NMR at Los Alamos

    International Nuclear Information System (INIS)

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

  16. 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...

  17. Applications of NMR spectroscopy to systems biochemistry.

    Science.gov (United States)

    Fan, Teresa W-M; Lane, Andrew N

    2016-02-01

    The past decades of advancements in NMR have made it a very powerful tool for metabolic research. Despite its limitations in sensitivity relative to mass spectrometric techniques, NMR has a number of unparalleled advantages for metabolic studies, most notably the rigor and versatility in structure elucidation, isotope-filtered selection of molecules, and analysis of positional isotopomer distributions in complex mixtures afforded by multinuclear and multidimensional experiments. In addition, NMR has the capacity for spatially selective in vivo imaging and dynamical analysis of metabolism in tissues of living organisms. In conjunction with the use of stable isotope tracers, NMR is a method of choice for exploring the dynamics and compartmentation of metabolic pathways and networks, for which our current understanding is grossly insufficient. In this review, we describe how various direct and isotope-edited 1D and 2D NMR methods can be employed to profile metabolites and their isotopomer distributions by stable isotope-resolved metabolomic (SIRM) analysis. We also highlight the importance of sample preparation methods including rapid cryoquenching, efficient extraction, and chemoselective derivatization to facilitate robust and reproducible NMR-based metabolomic analysis. We further illustrate how NMR has been applied in vitro, ex vivo, or in vivo in various stable isotope tracer-based metabolic studies, to gain systematic and novel metabolic insights in different biological systems, including human subjects. The pathway and network knowledge generated from NMR- and MS-based tracing of isotopically enriched substrates will be invaluable for directing functional analysis of other 'omics data to achieve understanding of regulation of biochemical systems, as demonstrated in a case study. Future developments in NMR technologies and reagents to enhance both detection sensitivity and resolution should further empower NMR in systems biochemical research. PMID:26952191

  18. NMR-based milk metabolomics

    DEFF Research Database (Denmark)

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

    2013-01-01

    Milk is a key component in infant nutrition worldwide and, in the Western parts of the world, also in adult nutrition. Milk of bovine origin is both consumed fresh and processed into a variety of dairy products including cheese, fermented milk products, and infant formula. The nutritional quality...... and processing capabilities of bovine milk is closely associated to milk composition. Metabolomics is ideal in the study of the low-molecular-weight compounds in milk, and this review focuses on the recent nuclear magnetic resonance (NMR)-based metabolomics trends in milk research, including...... applications linking the milk metabolite profiling with nutritional aspects, and applications which aim to link the milk metabolite profile to various technological qualities of milk. The metabolite profiling studies encompass the identification of novel metabolites, which potentially can be used as biomarkers...

  19. An NMR and ab initio quantum chemical study of acid-base equilibria for conformationally constrained acidic alpha-amino acids in aqueous solution

    DEFF Research Database (Denmark)

    Nielsen, Peter Aadal; Jaroszewski, Jerzy W.; Norrby, Per-Ola; Liljefors, Tommy

    2001-01-01

    The protonation states of a series of piperidinedicarboxylic acids (PDAs), which are conformationally constrained acidic alpha -amino acids, have been studied by C-13 NMR titration in water. The resulting data have been correlated with theoretical results obtained by HF/6-31+G* calculations using...... the polarizable continuum model (PCM) fore the description of water. The PDAs are highly ionizable and contain one or two possible internal hydrogen bonds. In the present study, we show that the PCM model is able to reproduce the relative stabilities of the different protonation states of the PDAs...

  20. A study of 0 transverse polarization transfer in (p, n) reactions from 12C, 13C and 40Ca at 80 and 50 MeV

    International Nuclear Information System (INIS)

    Transverse-polarization-transfer coefficients DNN for the (p, n) reaction at θ=0 have been measured on 12C, 13C and 40Ca targets at Ep=80 MeV and the 12C and 13C targets at Ep=50 MeV. As for the 12C and 13C(p, n) reactions, DNN for the transitions corresponding to the Gamow-Teller type and the Fermi and Gamow-Teller mixed type are compared to distorted-wave Born-approximation calculations. Observed DNN values are reproduced reasonably well by the calculations employing either the effective interactions M3Y or the M3Ym in which VTτ and Vστ are modified. A value for R2=[σGT(0 )/σF(0 )][B(F)/B(GT)] is deduced by using only the DNN data from the 13C(p, n) reaction, and is roughly consistent with R=[1]/[55]Ep, empirically determined from the cross-section data at 0 . As for the 40Ca(p, n) reaction, the observed value for the giant-dipole-resonance region is DNN=0.23±0.05, indicating that the spinflip and non-spinflip resonances are unresolved. Utilizing information from higher-energy DNN data, the transition-strength ratio f of non-spinflip to spinflip and DNN(SF) pertinent to spinflip transitions have been deduced empirically for the giant-dipole-resonance region. Obtained f and DNN(SF) values are 1.4±0.4 and -0.25±0.10, respectively, and are roughly consistent with the RPA calculations. ((orig.))

  1. Indirectly detected chemical shift correlation NMR spectroscopy in solids under fast magic angle spinning

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Kanmi [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    on decoupling efficiency as well as scaling factors. Indirect detection with assistance of PMLGm$\\bar{x}$ during INEPTR transfer proved to offer the highest sensitivity gains of 3-10. In addition, the CRAMPS sequence was applied under fast MAS to increase the 1H resolution during t1 evolution in the traditional, 13C detected HETCOR scheme. Two naturally abundant solids, tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (f-MLF-OH) and brown coal, with well ordered and highly disordered structures, respectively, are studied to confirm the capabilities of these techniques. Concomitantly, a simple optimization of 1H homonuclear dipolar decoupling at MAS rates exceeding 10 kHz was developed (Chapter 4). The fine-tuned decoupling efficiency can be obtained by minimizing the signal loss due to transverse relaxation in a simple spin-echo experiment, using directly the sample of interest. The excellent agreement between observed decoupling pattern and earlier theoretical predictions confirmed the utility of this strategy. The properties of naturally abundant surface-bound fluorocarbon groups in mesoporous silica nanoparticles (MSNs) were investigated by the above-mentioned multidimensional solid-state NMR experiments and theoretical modeling (Chapter 5). Two conformations of (pentafluorophenyl)propyl groups (abbreviated as PFP) were determined as PFP-prone and PFP-upright, whose aromatic rings are located above the siloxane bridges and in roughly upright position, respectively. Several 1D and 2D NMR techniques were implemented in the characterizations, including indirectly detected 1H{l_brace}13C{r_brace} and 19F{l_brace}13C{r_brace} 2D HETCOR, Carr-Purcell-Meiboom-Gill (CPMG) assisted 29Si direct polarization and 29Si19F 2D experiments, 2D double-quantum (DQ) 19F MAS NMR spectra and spin-echo measurements

  2. NMR in solid ionic and nanoionics

    International Nuclear Information System (INIS)

    Full text: Nuclear Magnetic Resonance (NMR) is a spectroscopic technique which employs magnetic nuclei to study, among others, the dynamics of condensed matter at the atomic level. Thus, NMR has been and still is a successful instrument in the research field of solid electrolytes also known as solid ionics. This paper presents the typical NMR experiments performed in solid ionics together with some examples from nanoionics. The experiments to be discussed comprise: (i) measurements of the diffusion coefficient employing the pulsed-field gradient and the static fringe-field method; (ii) the experimentally related NMR imaging; (iii) double resonance experiments like spin-echo double resonance (SEDOR) and two-dimensional Fourier transform NMR (2D-FT NMR); (iv) various types of nuclear relaxation, in particular spin-lattice relaxation. The NMR techniques yield information on topics like the following: type and number of mobile atoms and defects, diffusion pathways (e.g. dimensionality restrictions), atomic jump frequencies, activation energy and activation volume of these movements, diffusion coefficient with activation energy and prefactor, correlation effects in atomic movements, space correlation factor, cooperative phenomena, symmetry of atomic sites, behavior at phase transitions. These applications will be illustrated by giving examples from crystals, glasses, and polymers. (author)

  3. An introduction to biological NMR spectroscopy

    International Nuclear Information System (INIS)

    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)

  4. Graphical programming for pulse automated NMR experiments

    International Nuclear Information System (INIS)

    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 (T2), and quadrupolar oscillations, performed in magnetic intermetallic compounds. (author)

  5. NMR imaging of the brain: initial impressions

    International Nuclear Information System (INIS)

    An NMR imaging system designed and built by Thorn-EMI Ltd was installed at Hammersmith Hospital in March 1981. In the first year of operation 180 patients and 40 volunteers have had cranial examinations and initial impressions bases on this experience are presented. Patients with a wide variety of neurological diseases have been studied to provide a basis for diagnostic interpretation, to define distinctive features, and to evaluate different types of scanning sequences. NMR imaging appears to be of considerable value in neurological diagnosis and has a number of advantages over CT. The detailed evaluation of NMR imaging will require much more work but the initial results are very promising

  6. Solid-state NMR of polymers

    Energy Technology Data Exchange (ETDEWEB)

    Mirau, P

    2001-07-01

    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{sub g}). This was recognised as being related to a change in chain dynamics above and below the T{sub 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

  7. Solid-state NMR of polymers

    International Nuclear Information System (INIS)

    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 (Tg). This was recognised as being related to a change in chain dynamics above and below the Tg. 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 solids

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Richard [Huazhong University of Science and Technology, School of Software Engineering (China); Wang, Yan [Huazhong University of Science and Technology, School of Life Science and Technology (China); Xue, Zhidong, E-mail: zdxue@hust.edu.cn [Huazhong University of Science and Technology, School of Software Engineering (China); Zhang, Yang, E-mail: zhng@umich.edu [University of Michigan, Department of Computational Medicine and Bioinformatics (United States)

    2015-08-15

    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.

  10. In vivo determination of very-low-density lipoprotein-apolipoprotein B100 secretion rates in humans with a low dose of L-[1-C-13]valine and isotope ratio mass spectrometry

    NARCIS (Netherlands)

    de Sain-van der Velden, MGM; Rabelink, TJ; Gadellaa, MM; Elzinga, H; Reijngoud, DJ; Kuipers, F; Stellaard, F

    1998-01-01

    The aim of the present study was to determine the rate of very-low-density lipoprotein (VLDL)-apolipoprotein (apo) B100 secretion in humans with a minimized amount of L-[1-C-13]valine infusion in combination with the use of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) an

  11. Determination of low isotopic enrichment of L-[1-C-13]valine by gas chromatography combustion isotope ratio mass spectrometry : a robust method for measuring protein fractional synthetic rates in vivo

    NARCIS (Netherlands)

    Reijngoud, DJ; Hellstern, G; Elzinga, H; de Sain-van der Velden, MG; Okken, A; Stellaard, F

    1998-01-01

    A method was developed for measuring protein fractional synthetic rates using the N-methoxycarbonylmethyl ester (MCM) derivative of L-[1-C-13]valine and on-line gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The derivatization procedure can be performed rapidly and GC sep

  12. Interfaces in polymer nanocomposites - An NMR study

    Science.gov (United States)

    Böhme, Ute; Scheler, Ulrich

    2016-03-01

    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. 1H relaxation NMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the transverse relaxation time T2 is most suited. In this presentation we report on two applications of T2 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.

  13. 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.

  14. Characterization of Hydrogenated Fullerenes by NMR Spectroscopy

    Science.gov (United States)

    Hedenström, Mattias; Wågberg, Thomas; Johnels, Dan

    NMR spectroscopy is so far the only analytical technique that has been used to get a detailed structural characterization of hydrogenated fullerenes. A substantial amount of information derived from different NMR experiments can thus be found in the literature for a number of fullerenes hydrogenated to various degrees. These studies have benefitted from the fact that chemical shifts of 1H and 13C and in some cases also 3He can be used to obtain structural information of these compounds. Such results, together with discussions about different NMR experiments and general considerations regarding sample preparations, are summarized in this chapter. The unique information, both structural and physicochemical, that can be derived from different NMR experiments ensures that this technique will continue to be of central importance in characterization of hydrogenated fullerenes.

  15. NMR spectroscopy assists synthetic fuels research

    Energy Technology Data Exchange (ETDEWEB)

    Cookson, D.J.; Smith, B.E.

    1983-01-01

    NMR spectroscopy has proved to be a useful and versatile technique for the study of synthetic fuels feedstocks, catalysts, process intermediates and final products. Some applications of the technique to coal and gas conversion research are illustrated and discussed.

  16. NMR studies of cerebral metabolism in vivo

    International Nuclear Information System (INIS)

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

  17. NMR study of hydride systems

    International Nuclear Information System (INIS)

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

  18. Rheology of Blood by NMR

    Science.gov (United States)

    Han, Song-I.; Marseille, Oliver; Gehlen, Christa; Blümich, Bernhard

    2001-09-01

    Pipe flow of blood in tubes of 1 and 7 mm inner diameter, respectively, was investigated employing two-dimensional NMR velocity imaging and PFG propagator measurements at different Reynolds numbers between 10 and 3500. The results are compared to flow of a water/glycerol mixture of matching viscosity under identical conditions. The transition from laminar to turbulent flow is observed by both a flattening of the velocity profile and a change of the propagator shape. For blood flow this transition is found to be shifted toward higher Reynolds numbers as compared to the transition of the water/glycerol mixture. This observation is in agreement with predictions from hydraulic measurements and is a consequence of the non-Newtonian flow characteristics of blood as a suspension of erythrocytes and plasma. Likewise, a deviation from the laminar flow condition is observed for blood at low Reynolds numbers between 10 and 100. This phenomenon is unknown for Newtonian liquids and is explained by the onset of a geometrical arrangement of the erythrocytes, the so-called rouleaux effect.

  19. Observation of supramolecular aggregation by dosy NMR

    Czech Academy of Sciences Publication Activity Database

    Šaman, David; Wimmer, Zdeněk; Kolehmainen, E.

    Tatranská Lomnica : Slovak National NMR Centre. Slovak Chemical Society, 2011 - (Liptaj, T.; Imrich, J.; Kovaľaková, M.; Olčák, D.). s. 56-56 ISBN 978-80-89284-77-1. [Magnetic Moments in Central Europe. 16.03.2011-20.03.2011, Tatranská Lomnica] R&D Projects: GA MŠk 2B06024 Institutional research plan: CEZ:AV0Z40550506 Keywords : difusion * NMR Subject RIV: CC - Organic Chemistry

  20. NMR Investigation of the Quantum Piegonhole Effect

    OpenAIRE

    S., Anjusha V.; Hegde, Swathi S.; Mahesh, T. S.

    2015-01-01

    Quantum simulators based on nuclear spin-systems controlled by NMR techniques have been used for studying various quantum phenomena. In this work, using a four-qubit NMR quantum simulator, we investigate the recently postulated quantum pigeon-hole effect. In mathematics, the pigeonhole effect is described by a set of three objects being allocated with only two containers. Classically, one would expect at least one container to accommodate more than one object. However, recently it was predict...

  1. NMR of Membrane Proteins: Beyond Crystals.

    Science.gov (United States)

    Rajesh, Sundaresan; Overduin, Michael; Bonev, Boyan B

    2016-01-01

    Membrane proteins are essential for the flow of signals, nutrients and energy between cells and between compartments of the cell. Their mechanisms can only be fully understood once the precise structures, dynamics and interactions involved are defined at atomic resolution. Through advances in solution and solid state NMR spectroscopy, this information is now available, as demonstrated by recent studies of stable peripheral and transmembrane proteins. Here we highlight recent cases of G-protein coupled receptors, outer membrane proteins, such as VDAC, phosphoinositide sensors, such as the FAPP-1 pleckstrin homology domain, and enzymes including the metalloproteinase MMP-12. The studies highlighted have resulted in the determination of the 3D structures, dynamical properties and interaction surfaces for membrane-associated proteins using advanced isotope labelling strategies, solubilisation systems and NMR experiments designed for very high field magnets. Solid state NMR offers further insights into the structure and multimeric assembly of membrane proteins in lipid bilayers, as well as into interactions with ligands and targets. Remaining challenges for wider application of NMR to membrane structural biology include the need for overexpression and purification systems for the production of isotope-labelled proteins with fragile folds, and the availability of only a few expensive perdeuterated detergents.Step changes that may transform the field include polymers, such as styrene maleic acid, which obviate the need for detergent altogether, and allow direct high yield purification from cells or membranes. Broader demand for NMR may be facilitated by MODA software, which instantly predicts membrane interactive residues that can subsequently be validated by NMR. In addition, recent developments in dynamic nuclear polarization NMR instrumentation offer a remarkable sensitivity enhancement from low molarity samples and cell surfaces. These advances illustrate the current

  2. 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.

  3. NMR studies of multiphase flows II

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  4. 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.

  5. 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…

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

    DEFF Research Database (Denmark)

    Johansen, Kenneth; Wubshet, Sileshi Gizachew; Nyberg, Nils

    2013-01-01

    Time based trapping of chromatographically separated compounds on to solid-phase extraction cartridges (SPE) and subsequent elution to NMR-tubes was done to emulate the function of HPLC–NMR for dereplication purposes. Sufficient mass sensitivity was obtained by the use of a state-of-the-art HPLC...

  7. NMR standard probe for precision measurement of the free proton NMR frequency

    International Nuclear Information System (INIS)

    The authors have designed and constructed a special NMR standard probe using a spehrical pure water sample to determine the free proton NMR frequency fp at high field and an accuracy of 0.04 ppm has been achieved. Since the proton gyromagnetic ratio γp is less well known (∼0.1 ppm), the free proton NMR frequency measured by the probe may serve as a calibration standard for the magnetic field B. The standard probe can be used at various magnetic field values without introducing any additional magnetic perturbations. The probe is designed in such a way that a cylindrical sample or a small NMR probe can be inserted to replace the 1 cm diameter spherical water sample for systematic studies. Other NMR probes can be calibrated easily against the standard probe using a calibration form. Results will be presented and discussed

  8. BOOK REVIEW: NMR Imaging of Materials

    Science.gov (United States)

    Blümich, Bernhard

    2003-09-01

    Magnetic resonance imaging (MRI) of materials is a field of increasing importance. Applications extend from fundamental science like the characterization of fluid transport in porous rock, catalyst pellets and hemodialysers into various fields of engineering for process optimization and product quality control. While the results of MRI imaging are being appreciated by a growing community, the methods of imaging are far more diverse for materials applications than for medical imaging of human beings. Blümich has delivered the first book in this field. It was published in hardback three years ago and is now offered as a paperback for nearly half the price. The text provides an introduction to MRI imaging of materials covering solid-state NMR spectroscopy, imaging methods for liquid and solid samples, and unusual MRI in terms of specialized approaches to spatial resolution such as an MRI surface scanner. The book represents an excellent and thorough treatment which will help to grow research in materials MRI. Blümich developed the treatise over many years for his research students, graduates in chemistry, physics and engineering. But it may also be useful for medical students looking for a less formal discussion of solid-state NMR spectroscopy. The structure of this book is easy to perceive. The first three chapters cover an introduction, the fundamentals and methods of solid-state NMR spectroscopy. The book starts at the ground level where no previous knowledge about NMR is assumed. Chapter 4 discusses a wide variety of transformations beyond the Fourier transformation. In particular, the Hadamard transformation and the 'wavelet' transformation are missing from most related books. This chapter also includes a description of noise-correlation spectroscopy, which promises the imaging of large objects without the need for extremely powerful radio-frequency transmitters. Chapters 5 and 6 cover basic imaging methods. The following chapter about the use of relaxation and

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

    International Nuclear Information System (INIS)

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

  10. Characterization by NMR of ozonized methyl linoleate

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

  11. 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. PMID:10783273

  12. A modularized pulse programmer for NMR spectroscopy

    International Nuclear Information System (INIS)

    A modularized pulse programmer for a NMR spectrometer is described. It consists of a networked PCI-104 single-board computer and a field programmable gate array (FPGA). The PCI-104 is dedicated to translate the pulse sequence elements from the host computer into 48-bit binary words and download these words to the FPGA, while the FPGA functions as a sequencer to execute these binary words. High-resolution NMR spectra obtained on a home-built spectrometer with four pulse programmers working concurrently demonstrate the effectiveness of the pulse programmer. Advantages of the module include (1) once designed it can be duplicated and used to construct a scalable NMR/MRI system with multiple transmitter and receiver channels, (2) it is a totally programmable system in which all specific applications are determined by software, and (3) it provides enough reserve for possible new pulse sequences

  13. Deuterium NMR, induced and intrinsic cholesteric lyomesophases

    International Nuclear Information System (INIS)

    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.)

  14. Handbook of tritium NMR spectroscopy and applications

    International Nuclear Information System (INIS)

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

  15. NMR Microscopy - Micron-Level Resolution.

    Science.gov (United States)

    Kwok, Wing-Chi Edmund

    1990-01-01

    Nuclear Magnetic Resonance Imaging (MRI) has been developed into a powerful and widely used diagnostic tool since the invention of techniques using linear magnetic field gradients in 1973. The variety of imaging contrasts obtainable in MRI, such as spin density, relaxation times and flow rate, gives MRI a significant advantage over other imaging techniques. For common diagnostic applications, image resolutions have been in the order of millimeters with slice thicknesses in centimeters. For many research applications, however, resolutions in the order of tens of microns or smaller are needed. NMR Imaging in these high resolution disciplines is known as NMR microscopy. Compared with conventional microscopy, NMR microscopy has the advantage of being non-invasive and non-destructive. The major obstacles of NMR microscopy are low signal-to-noise ratio and effects due to spin diffusion. To overcome these difficulties, more sensitive RF probes and very high magnetic field gradients have to be used. The most effective way to increase sensitivity is to build smaller probes. Microscope probes of different designs have been built and evaluated. Magnetic field gradient coils that can produce linear field gradients up to 450 Gauss/cm were also assembled. In addition, since microscope probes often employ remote capacitors for RF tuning, the associated signal loss in the transmission line was studied. Imaging experiments have been carried out in a 2.1 Tesla small bore superconducting magnet using the typical two-dimensional spin warp imaging technique. Images have been acquired for both biological and non-biological samples. The highest resolution was obtained in an image of a nerve bundle from the spinal cord of a racoon and has an in-plane resolution of 4 microns. These experiments have demonstrated the potential application of NMR microscopy to pathological research, nervous system study and non -destructive testings of materials. One way to further improve NMR microscopy is

  16. The Quiet Renaissance of Protein NMR

    Science.gov (United States)

    Barrett, Paul J.; Chen, Jiang; Cho, Min-Kyu; Kim, Ji-Hun; Lu, Zhenwei; Mathew, Sijo; Peng, Dungeng; Song, Yuanli; Van Horn, Wade D.; Zhuang, Tiandi; Sönnichsen, Frank D.; Sanders, Charles R.

    2013-01-01

    From roughly 1985 through the start of the new millennium, the cutting edge of solution protein nuclear magnetic resonance (NMR) spectroscopy was to a significant extent driven by the aspiration to determine structures. Here we survey recent advances in protein NMR that herald a renaissance in which a number of its most important applications reflect the broad problem-solving capability displayed by this method during its classical era during the 1970s and early 80s. “Without receivers fitted and kept in order, the air may tingle and thrill with the message, but it will not reach my spirit and consciousness.” Mary Slessor, Calabar, circa 1910 PMID:23368985

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

    OpenAIRE

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

    2016-01-01

    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). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 ...

  18. Benzhydroximic Acids - NMR Study of Trimethylsilyl Derivatives

    Czech Academy of Sciences Publication Activity Database

    Schraml, Jan; Kvíčalová, Magdalena; Soukupová, Ludmila; Blechta, Vratislav; Exner, Otto

    2000-01-01

    Roč. 597, 1-2 (2000), s. 200-205. ISSN 0022-328X R&D Projects: GA AV ČR IAA4072605; GA MŠk LB98233 Keywords : trimethylsilyl derivatives * substituted benzhydroximic acids * NMR chemical shifts Subject RIV: CC - Organic Chemistry Impact factor: 1.632, year: 2000

  19. Responsibilities of NMR application in research

    International Nuclear Information System (INIS)

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

  20. NMR study of multiferroic iron niobate perovskites

    Czech Academy of Sciences Publication Activity Database

    Kouřil, K.; Chlan, V.; Štěpánková, H.; Řezníček, R.; Laguta, Valentyn; Raevski, I. P.

    Warszawa : Polish Academy of Sciences, 2015, s. 234-236. ISSN 0587-4246. [The European Conference PHYSICS OF MAGNETISM 2014/PM'14/. Poznań (PL), 23.06.2014-27.06.2014] R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : multiferroics * magnetism * NMR Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. The bar coil for NMR tomograph

    International Nuclear Information System (INIS)

    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

  2. Molecular dynamics - NMR experiments and simulations

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Hodgkinson, P.; Kessler, Jiří; Bouř, Petr

    Brno : Masaryk University Press, 2015 - (Sklenář, V.). s. 277-278 ISBN 978-80-210-7890-1. [EUROMAR 2015. 05.07.2015-10.07.2015, Praha] Institutional support: RVO:61388963 Keywords : molecular dynamics * NMR spectroscopy * MD simulations Subject RIV: CF - Physical ; Theoretical Chemistry

  3. 3D Reconstruction of NMR Images

    OpenAIRE

    Peter Izak; Milan Smetana; Libor Hargas; Miroslav Hrianka; Pavol Spanik

    2007-01-01

    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.

  4. Novel NMR Method for Organic Aerosol Analysis

    Czech Academy of Sciences Publication Activity Database

    Horník, Štěpán

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

  5. Some exercises in quantitative NMR imaging

    International Nuclear Information System (INIS)

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

  6. Novel NMR Method for Organic Aerosol Analysis

    Czech Academy of Sciences Publication Activity Database

    Horník, Štěpán

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

  7. 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.

  8. SQUID detected NMR in microtesla magnetic fields

    Science.gov (United States)

    Matlachov, Andrei N.; Volegov, Petr L.; Espy, Michelle A.; George, John S.; Kraus, Robert H.

    2004-09-01

    We have built an NMR system that employs a superconducting quantum interference device (SQUID) detector and operates in measurement fields of 2-25 μT. The system uses a pre-polarizing field from 4 to 30 mT generated by simple room-temperature wire-wound coils that are turned off during measurements. The instrument has an open geometry with samples located outside the cryostat at room-temperature. This removes constraints on sample size and allows us to obtain signals from living tissue. We have obtained 1H NMR spectra from a variety of samples including water, mineral oil, and a live frog. We also acquired gradient encoded free induction decay (FID) data from a water-plastic phantom in the μT regime, from which simple projection images were reconstructed. NMR signals from samples inside metallic containers have also been acquired. This is possible because the penetration skin depth is much greater at the low operating frequencies of this system than for conventional systems. Advantages to ultra-low field NMR measurements include lower susceptibility artifacts caused by high strength polarizing and measurement fields, and negligible line width broadening due to measurement field inhomogeneity, reducing the burden of producing highly homogeneous fields.

  9. Combining solid-state NMR spectroscopy with first-principles calculations - a guide to NMR crystallography.

    Science.gov (United States)

    Ashbrook, Sharon E; McKay, David

    2016-06-01

    Recent advances in the application of first-principles calculations of NMR parameters to periodic systems have resulted in widespread interest in their use to support experimental measurement. Such calculations often play an important role in the emerging field of "NMR crystallography", where NMR spectroscopy is combined with techniques such as diffraction, to aid structure determination. Here, we discuss the current state-of-the-art for combining experiment and calculation in NMR spectroscopy, considering the basic theory behind the computational approaches and their practical application. We consider the issues associated with geometry optimisation and how the effects of temperature may be included in the calculation. The automated prediction of structural candidates and the treatment of disordered and dynamic solids are discussed. Finally, we consider the areas where further development is needed in this field and its potential future impact. PMID:27117884

  10. e-NMR gLite grid enabled infrastructure

    NARCIS (Netherlands)

    Ferreira, N.L.; Wassenaar, T.A.; de Vries, S.J.; van Dijk, M.; van der Schot, G.; van der Zwan, J.; Boelens, R.; Bonvin, A.M.J.J.; Giachetti, A.; Carotenuto, D.; Rosato, A.; Bertini, I.; Herrmann, T.; Bagaria, A.; Zharavin, V.; Jonker, H.R.A.; Güntert, P.; Schwalbe, H.; Vranken, W.F.

    2010-01-01

    The e-NMR project is an European e-infrastructure that aims at providing the bio-NMR community with a software platform integrating and streamlining computational approaches necessary for NMR data analysis. The infrastructure is grid enabled with fteen gLite based partners sharing computational reso

  11. Several Applications of NMR in Organic Chemistry Research

    Institute of Scientific and Technical Information of China (English)

    CUI yuxin; LIU xuehui; XU hao

    2001-01-01

    @@ Modem NMR techniques, especially 2D-NMR have presented their powerful application in organic chemistry. Not only in structural determination, mechanism investigation, but also in solution conformation study for natural products. In this paper, various pulse field gradient NMR techniques such as COSY, NOESY, HMBC and HMQC were combined to study these problems.

  12. 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...

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

    International Nuclear Information System (INIS)

    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

  14. 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. PMID:26974032

  15. NMR Constraints Analyser: a web-server for the graphical analysis of NMR experimental constraints.

    Science.gov (United States)

    Heller, Davide Martin; Giorgetti, Alejandro

    2010-07-01

    Nuclear magnetic resonance (NMR) spectroscopy together with X-ray crystallography, are the main techniques used for the determination of high-resolution 3D structures of biological molecules. The output of an NMR experiment includes a set of lower and upper limits for the distances (constraints) between pairs of atoms. If the number of constraints is high enough, there will be a finite number of possible conformations (models) of the macromolecule satisfying the data. Thus, the more constraints are measured, the better defined these structures will be. The availability of a user-friendly tool able to help in the analysis and interpretation of the number of experimental constraints per residue, is thus of valuable importance when assessing the levels of structure definition of NMR solved biological macromolecules, in particular, when high-quality structures are needed in techniques such as, computational biology approaches, site-directed mutagenesis experiments and/or drug design. Here, we present a free publicly available web-server, i.e. NMR Constraints Analyser, which is aimed at providing an automatic graphical analysis of the NMR experimental constraints atom by atom. The NMR Constraints Analyser server is available from the web-page http://molsim.sci.univr.it/constraint. PMID:20513646

  16. Sensitivity enhancement using paramagnetic relaxation in MAS solid-state NMR of perdeuterated proteins

    Science.gov (United States)

    Linser, Rasmus; Chevelkov, Veniamin; Diehl, Anne; Reif, Bernd

    2007-12-01

    Previously, Ishii et al., could show that chelated paramagnetic ions can be employed to significantly decrease the recycle delay of a MAS solid-state NMR experiment [N.P. Wickramasinghe, M. Kotecha, A. Samoson, J. Past, Y. Ishii, Sensitivity enhancement in C-13 solid-state NMR of protein microcrystals by use of paramagnetic metal ions for optimizing H-1 T-1 relaxation, J. Magn. Reson. 184 (2007) 350-356]. Application of the method is limited to very robust samples, for which sample stability is not compromised by RF induced heating. In addition, probe integrity might be perturbed in standard MAS PRE experiments due to the use of very short duty cycles. We show that these deleterious effects can be avoided if perdeuterated proteins are employed that have been re-crystallized from D 2O:H 2O = 9:1 containing buffer solutions. The experiments are demonstrated using the SH3 domain of chicken α-spectrin as a model system. The labeling scheme allows to record proton detected 1H, 15N correlation spectra with very high resolution in the absence of heteronuclear dipolar decoupling. Cu-edta as a doping reagent yields a reduction of the recycle delay by up to a factor of 15. In particular, we find that the 1H T1 for the bulk H N magnetization is reduced from 4.4 s to 0.3 s if the Cu-edta concentration is increased from 0 mM to 250 mM. Possible perturbations like chemical shift changes or line broadening due to the paramagnetic chelate complex are minimal. No degradation of our samples was observed in the course of the experiments.

  17. CPMG sequences with enhanced sensitivity to chemical exchange

    International Nuclear Information System (INIS)

    Improved relaxation-compensated Carr-Purcell-Meiboom-Gill pulse sequences are reported for studying chemical exchange of backbone 15N nuclei. In contrast to the original methods [J. P. Loria, M. Rance, and A. G. Palmer, J. Am. Chem. Soc.121, 2331-2332 (1999)], phenomenological relaxation rate constants obtained using the new sequences do not contain contributions from 1H-1H dipole-dipole interactions. Consequently, detection and quantification of chemical exchange processes are facilitated because the relaxation rate constant in the limit of fast pulsing can be obtained independently from conventional 15N spin relaxation measurements. The advantages of the experiments are demonstrated using basic pancreatic trypsin inhibitor

  18. Solid-state NMR Study of the YadA Membrane-Anchor Domain in the Bacterial Outer Membrane.

    Science.gov (United States)

    Shahid, Shakeel A; Nagaraj, Madhu; Chauhan, Nandini; Franks, Trent W; Bardiaux, Benjamin; Habeck, Michael; Orwick-Rydmark, Marcella; Linke, Dirk; van Rossum, Barth-J

    2015-10-19

    MAS-NMR was used to study the structure and dynamics at ambient temperatures of the membrane-anchor domain of YadA (YadA-M) in a pellet of the outer membrane of E. coli in which it was expressed. YadA is an adhesin from the pathogen Yersinia enterocolitica that is involved in interactions with the host cell, and it is a model protein for studying the autotransport process. Existing assignments were sucessfully transferred to a large part of the YadA-M protein in the E. coli lipid environment by using (13) C-(13) C DARR and PDSD spectra at different mixing times. The chemical shifts in most regions of YadA-M are unchanged relative to those in microcrystalline YadA-M preparations from which a structure has previously been solved, including the ASSA region that is proposed to be involved in transition-state hairpin formation for transport of the soluble domain. Comparisons of the dynamics between the microcrystalline and membrane-embedded samples indicate greater flexibility of the ASSA region in the outer-membrane preparation at physiological temperatures. This study will pave the way towards MAS-NMR structure determination of membrane proteins, and a better understanding of functionally important dynamic residues in native membrane environments. PMID:26332158

  19. Squid detected NMR and MRI at ultralow fields

    Science.gov (United States)

    Clarke, John; Pines, Alexander; McDermott, Robert F.; Trabesinger, Andreas H.

    2008-12-16

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

  20. Solid state NMR of biopolymers and synthetic polymers

    International Nuclear Information System (INIS)

    Solid state NMR has been invaluable in evaluating the structure, phase separation, and dynamics of polymers. Because polymers are generally used in the solid state, solid state NMR is especially powerful because it provides information about the materials in their native state. This review gives a general overview of solid state NMR, concentrating on solid state 13 C and 2 H NMR. It then focuses on two examples: the biopolymer spider silka and the engineering material polyurethane. It illustrates how solid state NMR can provide new information about synthetic and bio-polymers. (author)

  1. The dynamic of the contact between Humaita fields and the natural forest of south Amazonas through the isotopic study (12 C, 13 C and 14 C) of the soil organic matter

    International Nuclear Information System (INIS)

    This paper presents isotopic data (12 C, 13 C and 14 C) of five soil profiles from the southern region of State of Amazonas, where is located the Campos de Humaita (savannah) vegetation community, surrounded by the tropical forest. The objective is to supply information about probable palaeoclimatic and palaeovegetation changes occurred in the tropical region for the last 10,000 years. Stable carbon isotopes of the soil organic matter (SOM) were used for the characterization of the expansion/regression process of the ecosystem equilibrium, and the radiocarbon dating of the SOM to establish the chronology. (author). 24 refs., 3 tabs

  2. NMR with excitation modulated by Frank sequences.

    Science.gov (United States)

    Blümich, Bernhard; Gong, Qingxia; Byrne, Eimear; Greferath, Marcus

    2009-07-01

    Miniaturized NMR is of growing importance in bio-, chemical, and -material sciences. Other than the magnet, bulky components are the radio-frequency power amplifier and the power supply or battery pack. We show that constant flip-angle excitation with phase modulation following a particular type of polyphase perfect sequences results in low peak excitation power at high response peak power. It has ideal power distribution in both the time domain and the frequency domain. A savings in peak excitation power of six orders of magnitude has been realized compared to conventionally pulsed excitation. Among others, the excitation promises to be of use for button-cell operated miniature NMR devices as well as for complying with specific-absorption-rate regulations in high-field medical imaging. PMID:19386525

  3. Nuclear spin noise in NMR revisited

    Science.gov (United States)

    Ferrand, Guillaume; Huber, Gaspard; Luong, Michel; Desvaux, Hervé

    2015-09-01

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

  4. Nuclear spin noise in NMR revisited

    CERN Document Server

    Ferrand, Guillaume; Luong, Michel; Desvaux, Hervé

    2015-01-01

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

  5. TROSY NMR with partially deuterated proteins.

    Science.gov (United States)

    Eletsky, A; Kienhöfer, A; Pervushin, K

    2001-06-01

    TROSY-type optimization of liquid-state NMR experiments is based on the preservation of unique coherence transfer pathways with distinct transverse relaxation properties. The broadband decoupling of the 1H spins interchanges the TROSY and anti-TROSY magnetization transfer pathways and thus is not used in TROSY-type triple resonance experiments or is replaced with narrowband selective decoupling. To achieve the full advantage of TROSY, the uniform deuteration of proteins is usually required. Here we propose a new and general method for 1H broadband decoupling in TROSY NMR, which does not compromise the relaxation optimization in the 15N-1H moieties, but uniformly and efficiently refocuses the 1JCH scalar coupling evolution in the 13C-1H moieties. Combined with the conventional 2H decoupling, this method enables obtaining high sensitivity TROSY-type triple resonance spectra with partially deuterated or fully protonated 13C,15N labeled proteins. PMID:11495249

  6. NMR Quantum Calculations of the Jones Polynomial

    CERN Document Server

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

    2009-01-01

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

  7. NMR-based diffusion lattice imaging.

    Science.gov (United States)

    Laun, Frederik Bernd; Müller, Lars; Kuder, Tristan Anselm

    2016-03-01

    Nuclear magnetic resonance (NMR) diffusion experiments are widely employed as they yield information about structures hindering the diffusion process, e.g., about cell membranes. While it has been shown in recent articles that these experiments can be used to determine the shape of closed pores averaged over a volume of interest, it is still an open question how much information can be gained in open well-connected systems. In this theoretical work, it is shown that the full structure information of connected periodic systems is accessible. To this end, the so-called "SEquential Rephasing by Pulsed field-gradient Encoding N Time intervals" (SERPENT) sequence is used, which employs several diffusion encoding gradient pulses with different amplitudes. Two two-dimensional solid matrices that are surrounded by an NMR-visible medium are considered: a hexagonal lattice of cylinders and a rectangular lattice of isosceles triangles. PMID:27078384

  8. 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.

  9. An NMR study on shale wettability

    Energy Technology Data Exchange (ETDEWEB)

    Odusina, Elijah; Sondergeld, Carl; Rai, Chandra [University of Oklahoma (United States)

    2011-07-01

    In recent years, the importance of shales as unconventional gas resources has grown significantly. It is therefore important to reach a better understanding of their petrophysical properties. One of the important rock properties that is directly linked to successful hydrocarbon recovery is wettability. This paper presents a study on shale wettability using nuclear magnetic resonance (NMR) to monitor sequential imbibition of brine and oil. Due to the presence of mineralogical variations, low permeability and viscosity, and complex pore structure, the interpretation of wettability using conventional approaches becomes complex. Samples that included 21 core plugs from the Eagle Ford shale, 12 from the Barnett, 11 from the Floyd, and 10 from the Woodford shale were analyzed. The NMR study confirmed the water-wet behavior of Berea sandstone. From the study, it was seen that the Woodford shale showed more affinity for dodecane than did the other shales.

  10. DNA oligonucleotide conformations: high resolution NMR studies

    International Nuclear Information System (INIS)

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

  11. NMR-Based Diffusion Lattice Imaging

    CERN Document Server

    Laun, Frederik Bernd

    2013-01-01

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

  12. NMR spectral analysis using prior knowledge

    Science.gov (United States)

    Kasai, Takuma; Nagata, Kenji; Okada, Masato; Kigawa, Takanori

    2016-03-01

    Signal assignment is a fundamental step for analyses of protein structure and dynamics with nuclear magnetic resonance (NMR). Main-chain signal assignment is achieved with a sequential assignment method and/or an amino-acid selective stable isotope labeling (AASIL) method. Combinatorial selective labeling (CSL) methods, as well as our labeling strategy, stable isotope encoding (SiCode), were developed to reduce the required number of labeled samples, since one of the drawbacks of AASIL is that many samples are needed. Signal overlapping in NMR spectra interferes with amino-acid determination by CSL and SiCode. Since spectral deconvolution by peak fitting with a gradient method cannot resolve closely overlapped signals, we developed a new method to perform both peak fitting and amino acid determination simultaneously, with a replica exchange Monte Carlo method, incorporating prior knowledge of stable-isotope labeling ratios and the amino-acid sequence of the protein.

  13. NMR-based diffusion lattice imaging

    Science.gov (United States)

    Laun, Frederik Bernd; Müller, Lars; Kuder, Tristan Anselm

    2016-03-01

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

  14. Fully automated system for pulsed NMR measurements

    International Nuclear Information System (INIS)

    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

  15. 1H NMR in a-Si

    Science.gov (United States)

    Carlos, W. E.; Taylor, P. C.

    1982-10-01

    Results of pulsed NMR studies of hydrogen in a-Si: H prepared at several laboratories by glow discharge of silane are presented. The origins of the two 1H NMR lines seen in almost all samples of a-Si: H are discussed. Solid-echo measurements are presented which indicate that these two components are due to spatially isolated groups of protons. We attribute the narrow line to protons slightly clustered in the bulk of the material and the broad line to protons distributed on internal surfaces. The spin-lattice relaxation time shows a minimum at T~30 K which is interpreted as due to relaxation via spin diffusion to a small number of H2 molecules acting as relaxation centers. Annealing results suggest that all the hydrogen molecules are trapped in very similar sites.

  16. Some nitrogen-14 NMR studies in solids

    International Nuclear Information System (INIS)

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

  17. NMR studies of nucleic acid dynamics

    Science.gov (United States)

    Al-Hashimi, Hashim M.

    2013-12-01

    Nucleic acid structures have to satisfy two diametrically opposite requirements; on one hand they have to adopt well-defined 3D structures that can be specifically recognized by proteins; on the other hand, their structures must be sufficiently flexible to undergo very large conformational changes that are required during key biochemical processes, including replication, transcription, and translation. How do nucleic acids introduce flexibility into their 3D structure without losing biological specificity? Here, I describe the development and application of NMR spectroscopic techniques in my laboratory for characterizing the dynamic properties of nucleic acids that tightly integrate a broad set of NMR measurements, including residual dipolar couplings, spin relaxation, and relaxation dispersion with sample engineering and computational approaches. This approach allowed us to obtain fundamental new insights into directional flexibility in nucleic acids that enable their structures to change in a very specific functional manner.

  18. Nuclear spin noise in NMR revisited

    Energy Technology Data Exchange (ETDEWEB)

    Ferrand, Guillaume; Luong, Michel [Laboratoire d’Ingénierie des Systèmes Accélérateurs et des Hyperfréquences, SACM, CEA, Université Paris-Saclay, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Huber, Gaspard; Desvaux, Hervé, E-mail: herve.desvaux@cea.fr [Laboratoire Structure et Dynamique par Résonance Magnétique, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA/Saclay, F-91191 Gif-sur-Yvette (France)

    2015-09-07

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

  19. Nuclear spin noise in NMR revisited

    International Nuclear Information System (INIS)

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

  20. 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.

  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. Probing Organometallic Reactions With 19F NMR

    OpenAIRE

    Hawrelak, Eric James

    2002-01-01

    This dissertation explores fundamental aspects of the reaction of group 4 metallocenes with methylaluminoxane (MAO) that lead to active Ziegler-Natta olefin polymerization catalysts. A novel experimental approach is described, in which a unique spectroscopic probe (a fluorinated substituent) is attached to the metallocene ancillary ligands and the metallocene/MAO mixtures are analyzed using 19F NMR spectroscopy. Group 4 metallocene dimethides bearing pentafluorophenyl (C6F5) substituents ...

  3. NMR investigations of G-quadruplex structures

    OpenAIRE

    Bessi, Irene

    2016-01-01

    This thesis deals with the NMR characterization of the structure and the folding dynamics of DNA G quadruplexes as potential therapeutic target in cancer therapy and building block for DNA based nanotechnology. The first part of this thesis (Chapters 1-5) introduces the reader to the world of G quadruplexes. The main features of the classic Watson Crick double helix and alternative non B DNA structures are illustrated in Chapter 1. Many different base pairing schemes are possible, besid...

  4. NMR of 1,2-dioxiquinolines

    International Nuclear Information System (INIS)

    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

  5. NMR Studies on Organic and Biological Solids

    OpenAIRE

    Yang, Chen

    2015-01-01

    Solid-state NMR (SSNMR) studies on biomolecules and organic molecular crystals are presented here. The biological part of the work is focused on improving resolution and sensitivity of SSNMR techniques for larger protein systems, while the studies on organic molecular crystals extend the application of SSNMR to determining the crystal structure of a photoreaction intermediate. First, a long-observation-window band-selective homonuclear decoupling scheme is introduced. The homonuclear decoupli...

  6. 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.

  7. Funktionelle NMR-Mikroskopie an Pflanzenwurzeln

    OpenAIRE

    Kaufmann, Ilja

    2009-01-01

    Als nicht-invasive Methode bietet die magnetische Kernspinresonanztomographie durch ihre Vielzahl an messbaren Größen wie Wassergehalt und Flussgeschwindigkeiten gute Voraussetzungen, um funktionelle Abläufe in Pflanzen und insbesondere Pflanzenwurzeln zu untersuchen. Für funktionelle NMR-Mikroskopie notwendige Hardware und Methoden wurden in dieser Arbeit entwickelt und angewendet. Aufgrund der starken Suszeptibilitätsunterschiede in den Proben und der notwendigen Zeitauflösung für funktione...

  8. Randomization improves sparse sampling in multidimensional NMR

    OpenAIRE

    Hoch, Jeffrey C.; Maciejewski, Mark W.; Filipovic, Blagoje

    2008-01-01

    While a number of strategies have been developed to reduce data collection requirements for multidimensional NMR based on non-Fourier methods of spectrum analysis, there is an increasing awareness that the principal differences in the performance of these methods is attributable to the sampling strategies employed, and not the method of spectrum analysis per se. The ability of maximum entropy reconstruction to utilize essentially arbitrary sampling schemes makes it an useful platform for comp...

  9. Rhodopsin-lipid interactions studied by NMR.

    Science.gov (United States)

    Soubias, Olivier; Gawrisch, Klaus

    2013-01-01

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

  10. 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. PMID:22057574

  11. 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...

  12. Cutoff-Free Traveling Wave NMR

    CERN Document Server

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

    2011-01-01

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

  13. Solid state NMR study of cumbaru flour

    International Nuclear Information System (INIS)

    The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T1Hρ). Knowing that the chemical structure and molecular dynamic are extremely necessary route to obtain information on the polysaccharides, this work contributes to the classification of the seed containing in the cumbaru fruit to get response on its application. To obtain the initial responses for our purposes some solid state NMR techniques were chosen. The CPMAS 13C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13C NMR spectrum showed the presence of domains with distinct molecular mobility, because these domains will differ basically in the distribution size and chain packing. The variable contact time experiment was used to analyse the distribution form of 13C decays, which give us more information about sample heterogeneity. The T1HρHr 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)

  14. Multispectral dual isotope and NMR image analysis

    International Nuclear Information System (INIS)

    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

  15. Discrete analysis of stochastic NMR.II

    Science.gov (United States)

    Wong, S. T. S.; Rods, M. S.; Newmark, R. D.; Budinger, T. F.

    Stochastic NMR is an efficient technique for high-field in vivo imaging and spectroscopic studies where the peak RF power required may be prohibitively high for conventional pulsed NMR techniques. A stochastic NMR experiment excites the spin system with a sequence of RF pulses where the flip angles or the phases of the pulses are samples of a discrete stochastic process. In a previous paper the stochastic experiment was analyzed and analytic expressions for the input-output cross-correlations, average signal power, and signal spectral density were obtained for a general stochastic RF excitation. In this paper specific cases of excitation with random phase, fixed flip angle, and excitation with two random components in quadrature are analyzed. The input-output cross-correlation for these two types of excitations is shown to be Lorentzian. Line broadening is the only spectral distortion as the RF excitation power is increased. The systematic noise power is inversely proportional to the number of data points N used in the spectral reconstruction. The use of a complete maximum length sequence (MLS) may improve the signal-to-systematic-noise ratio by 20 dB relative to random binary excitation, but peculiar features in the higher-order autocorrelations of MLS cause noise-like distortion in the reconstructed spectra when the excitation power is high. The amount of noise-like distortion depends on the choice of the MLS generator.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuanpeng Janet, E-mail: yphuang@cabm.rutgers.edu; Mao, Binchen; Xu, Fei; Montelione, Gaetano T., E-mail: gtm@rutgers.edu [Rutgers, The State University of New Jersey, Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, and Northeast Structural Genomics Consortium (United States)

    2015-08-15

    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 {sup 15}N–{sup 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.

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

    International Nuclear Information System (INIS)

    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 15N–1H 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

  18. Portable NMR systems for non destructive testing

    International Nuclear Information System (INIS)

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

  19. Magic-angle-spinning NMR (MAS-NMR) spectroscopy and the structure of zeolites

    International Nuclear Information System (INIS)

    After outlining the chemical features and properties which make zeolites such an important group of catalysts and sorbents, the article explains how high-resolution solid-state NMR with magic-angle spinning reveals numerous new insights into their structure. 29Si-MAS-NMR readily and quantitatively identifies five distinct Si(OAl)sub(n)(OSi)sub(4-n) structural groups in zeolitic frameworks (n=0,1,...4), corresponding to the first tetrahedral coordination shell of a silicon atom. Many catalytic and other chemical properties of zeolites are governed by the short-range Si, Al order, the nature of which is greatly clarified by 29Si-MAS-NMR. (orig./EF)

  20. Fast automated protein NMR data collection and assignment by ADAPT-NMR on Bruker spectrometers

    Science.gov (United States)

    Lee, Woonghee; Hu, Kaifeng; Tonelli, Marco; Bahrami, Arash; Neuhardt, Elizabeth; Glass, Karen C.; Markley, John L.

    2013-11-01

    ADAPT-NMR (Assignment-directed Data collection Algorithm utilizing a Probabilistic Toolkit in NMR) supports automated NMR data collection and backbone and side chain assignment for [U-13C, U-15N]-labeled proteins. Given the sequence of the protein and data for the orthogonal 2D 1H-15N and 1H-13C planes, the algorithm automatically directs the collection of tilted plane data from a variety of triple-resonance experiments so as to follow an efficient pathway toward the probabilistic assignment of 1H, 13C, and 15N signals to specific atoms in the covalent structure of the protein. Data collection and assignment calculations continue until the addition of new data no longer improves the assignment score. ADAPT-NMR was first implemented on Varian (Agilent) spectrometers [A. Bahrami, M. Tonelli, S.C. Sahu, K.K. Singarapu, H.R. Eghbalnia, J.L. Markley, PLoS One 7 (2012) e33173]. Because of broader interest in the approach, we present here a version of ADAPT-NMR for Bruker spectrometers. We have developed two AU console programs (ADAPT_ORTHO_run and ADAPT_NMR_run) that run under TOPSPIN Versions 3.0 and higher. To illustrate the performance of the algorithm on a Bruker spectrometer, we tested one protein, chlorella ubiquitin (76 amino acid residues), that had been used with the Varian version: the Bruker and Varian versions achieved the same level of assignment completeness (98% in 20 h). As a more rigorous evaluation of the Bruker version, we tested a larger protein, BRPF1 bromodomain (114 amino acid residues), which yielded an automated assignment completeness of 86% in 55 h. Both experiments were carried out on a 500 MHz Bruker AVANCE III spectrometer equipped with a z-gradient 5 mm TCI probe. ADAPT-NMR is available at http://pine.nmrfam.wisc.edu/ADAPT-NMR in the form of pulse programs, the two AU programs, and instructions for installation and use.

  1. Dynamic NMR of nano- and microstructured materials

    Energy Technology Data Exchange (ETDEWEB)

    Olaru, Maria Alexandra

    2013-07-01

    The fast technological advancement which took place over the past few decades sustained the development of various categories of advanced polymeric, composite and porous materials, with complex physical and chemical properties determined by their structure and dynamics at nano- and micrometer levels. This brought forth the necessity of combining different methods of analysis, which cover multiple length scales, in order to allow for a comprehensive characterization and a valid prediction of a material's macroscopic behaviour. The purpose of this work was to characterize the structure and dynamics of various types of nano- and micro structured systems, such as silane crosslinked poly(ethylene), cement-in-polymer dispersion with different compositions or model and natural porous media, using a combination of nuclear magnetic resonance (NMR) methods that provide relevant information on different length scales of interest. Data processing and interpretation was facilitated by self-made computational procedures and mathematical models. The different subjects approached in this work are briefly presented in Chapter 1 (Introduction) and discussed in detail further on in an order according to the length scale of the motion probed. In Chapter 2 proton NMR wideline spectroscopy is used to obtain information on the phase composition, molecular mobility and domain sizes of crosslinked poly(ethylene) (PE), a polymer commonly used in a broad range of applications, from day-to-day life basic commodities like water and sewage pipes, to insulating coatings for medium and high voltage wires. Due to its industrial importance, this type of PE has been previously characterized using a variety of methods. The novelty brought by this study is the quantitative analysis of the spin diffusion (SD) coefficients and domain sizes of different phases by a dedicated software developed for solving the spin diffusion equations for a lamellar morphology, using as input data extracted from NMR

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-01

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

  3. In-cell NMR in Xenopus laevis oocytes.

    Science.gov (United States)

    Thongwichian, Rossukon; Selenko, Philipp

    2012-01-01

    For the purpose of studying IDPs inside cells of higher organisms, several eukaryotic in-cell NMR systems have been developed over the past years. In this chapter we will focus on high-resolution in-cell NMR applications in Xenopus laevis oocytes, the first eukaryotic cellular model system to be established. In contrast to prokaryotic in-cell NMR samples, eukaryotic in-cell NMR specimens are prepared by cytoplasmic delivery of an exogenously produced, isotope-labeled protein into the non-isotope-labeled environment of the respective "host" cell. In-cell NMR applications in Xenopus oocytes rely on intracellular sample deposition by direct microinjection into the oocyte cytoplasm. Here, we describe the preparation of oocyte in-cell NMR samples for IDP studies in this cellular model environment. PMID:22760310

  4. 13C-NMR assignment, structure, and dynamics of deoxyoligonucleotides

    International Nuclear Information System (INIS)

    The unique spectral properties of 13C-NMR for studying nucleic acids and some of the important features of 13C-NMR in oligonucleotide studies are demostrated. The main difficulty in studying oligonucleotides by 13C-NMR and recent improvements in NMR instrumentation and advances in oligonucleotide synthesis are presented. The high resolution 13C-NMR spectra, T1 relaxation times and NOEs were measured for duplex of the self-complementary oligo-DNAs: d(CG)3 and d(GGTATACC) are studied. The target of this study is to developed a systematic 13C-NMR spectral assignment and to investigate the structure and dynamics of these two sequences by this techniques. (M.J.C.)

  5. The Expanding Role of NMR in Drug Discovery and Development

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ The role of NMR in the pharmaceutical industry has changed dramatically over the last decade. Once thought of as an analytical technique used primarily to support synthetic chemistry, NMR now has an important role in the investigation of biochemical changes involved in clinical diseases and drug toxicity. It is also used extensively to elucidate the structures of drug metabolites. Data obtained using LC NMR MS and 19F NMR will be used to illustrate the utility of hyphenated methods in identifying xenobiotic metabolites as part of a drug development program. The application of NMR to the study of potential drug toxicity will also be described using the cationic, amphiphilic drugs chloroquine and amiodarone. These drugs are known to induce phospholipidosis characterized by lysosomal lamellar bodies and drug accumulation. Using a metabonomic approach, NMR spectroscopy of urine allowed the identification of a combination of urinary biomarkers of phospholipidosis.

  6. Magic-angle-spinning NMR studies of zeolite SAPO-5

    Science.gov (United States)

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

    1988-01-01

    SAPO-5 was synthesized using triethylamine as template. Magic-angle-spinning (MAS) NMR of 1H, 27Al, 29Si and 31P was used to study the silicon incorporation into the framework and the nature of the Brønsted sites. 1H MAS NMR shows two types of bridging hydroxyl groups. 29Si MAS NMR indicates that silicon substitutes mostly for phosphorus and that there is a small amount of crystalline SiO 2 in the zeolite powder.

  7. Classical model for bulk-ensemble NMR quantum computation

    OpenAIRE

    Schack, R.; Caves, C. M.

    1999-01-01

    We present a classical model for bulk-ensemble NMR quantum computation: the quantum state of the NMR sample is described by a probability distribution over the orientations of classical tops, and quantum gates are described by classical transition probabilities. All NMR quantum computing experiments performed so far with three quantum bits can be accounted for in this classical model. After a few entangling gates, the classical model suffers an exponential decrease of the measured signal, whe...

  8. Studies on irradiation stability of polystyrene by NMR

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; SUN Wan-Fu; XIE Cheng-Xi

    2004-01-01

    The irradiation stability of polystyrene (PS) was studied by 13C and 1H NMR spectra, Nuclear Overhauser Relaxation (NOE) and 13C NMR spin-lattice relaxation time (T1). The results indicate that 13C and 1H NMR chemical shifts, NOE and T1 were almost invariant with the increase of irradiation dose. This shows that polystyrene is particularly stable within 2.5 kGy doses and the mechanism of its stability is discussed.

  9. Nuclear Magnetic Resonance Logging While Drilling (NMR-LWD)

    OpenAIRE

    Blanz, Martin; Kruspe, Thomas; Thern, Holger Frank; Kurz, Gerhard Alfons

    2015-01-01

    NMR T2 distribution measurement is our chosen everyday method for NMR logging while drilling oil and gas wells. This method yields straightforward preparation and execution of the job as well as a normally easy interpretation of the measured data. For instance, gas and light oil discrimination against water is feasible by direct observation of the T2 distribution. A condition for this measurement method is a NMR logging tool that hardly moves while drilling and in addition uses a small static...

  10. Solid-state NMR studies of globular and membrane proteins

    OpenAIRE

    Luca, Sorin

    2003-01-01

    Spektroskopie erlaubt die Eigenschaften und Struktur der Materie durch Einsatz elektromagnetischer Strahlung auf molekularer Ebene zu untersuchen. Die Kernspinresonanz (NMR) ist ein spezielles Gebiet der Spektroskopie, die die magnetischen Eigenschaften der Atomkerne auswertet. Ein kurzer Überblick über die historischen Weiterentwicklungen im Bereich der NMR ergibt sich aus einer Betrachtung der Nobelpreise, die bisher im Zusammenhang der NMR vergeben wurden: 1952 empfingen Felix Bloch und Ed...

  11. NMR Studies of Quantum Rotors Confined in Zeolite

    Science.gov (United States)

    Ji, Yu; Hamida, J. A.; Sullivan, N. S.

    2010-02-01

    We report the results of NMR studies of methane trapped in zeolite at low temperatures. Samples were prepared to contain 1.0±0.2 molecules per α-sodalite cage of zeolite-13X. The NMR spin-spin and spin-lattice relaxation times were measured for 4NMR spin-spin relaxation is seen at this “melting” transition.

  12. Hochfeld 1H-NMR-Mikroskopie zur biophysikalischen Grundlagenforschung

    OpenAIRE

    Haddad, Daniel

    2005-01-01

    Dank der mit modernen NMR-Spektrometern (Kernspintomographen) routinemäßig realisierbaren isotropen räumlichen Auflösungen von wenigen Mikrometern, ergeben sich für die 1H NMR-Mikroskopie zahlreiche neue Anwendungsgebiete. Allerdings sind die Möglichkeiten und Grenzen der NMR-Mikroskopie bezüglich ihrer praktischen Anwendbarkeit bisher nur wenig untersucht worden. Die vorliegende Arbeit ist im Bereich der biophysikalischen Grundlagenforschung angesiedelt und soll die praktische Anwendbarkeit ...

  13. Stroke, evolution of NMR imaging characteristics

    International Nuclear Information System (INIS)

    This study evaluates the NMR imaging characteristics of stroke and temporal evolution of these features. Patients with acute stroke clinically had NMR imaging (prototype 0.15T resistive imager, Technicare, Inc.) acutely (n=37), at approximately 2 weeks (n=31) and 3 months (n=10). Patients with old (> 1 yr.) stroke were also imaged (n=7). Partial saturation sequences were used employing echo time (T/sub E/) of 30, 60 and 120 msec, as well as inversion recovery (TR) sequences. Partial saturation images displayed a homogeneous increase in signal at lesion sites in both bland and hemorrhagic infarcts, reflection prolongation of spin-spin relaxation (T/sub 2/) due to increased tissue water content, blood and edema being indistinguishable. IR images recovered low signal from bland infarcts due to prolongation of spinlattice relaxation (T/sub 1/) by tissue edema, hemorrhagic lesions and short (T/sub 1/) centrally (blood) with moderate or increased IR signal, and low signal peripherally (edema). On follow-up IR imaging, hematomas developed low signal centres, possibly reflection cavitation, with short T/sub 2/ rims, possibly indicating the presence of iron-laden macrophages. In 2 patients with hemorrhagic infarcts an area of increased signal (prolonged T/sub 2/) was seen on initial partial saturation images in the homologous portion of the other hemisphere (normal by CT). This may reflect a local alteration of blood volume or velocity. In 5 patients with old infarcts, a rim of prolonged T/sub 2/ was seen at the periphery of old lesions, possibly reflecting a local chronic increase in extravascular or intravascular water, slowing of blood velocity, or a zone of neuronal dropout. Detailed pathophysiologic correlation is required to understand the basis of these NMR findings

  14. Stroke, evolution of NMR imaging characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, R.L.; Carr, T.; Kertesz, A.; Black, S.; Cooper, P.; Stewart, S.

    1984-01-01

    This study evaluates the NMR imaging characteristics of stroke and temporal evolution of these features. Patients with acute stroke clinically had NMR imaging (prototype 0.15T resistive imager, Technicare, Inc.) acutely (n=37), at approximately 2 weeks (n=31) and 3 months (n=10). Patients with old (> 1 yr.) stroke were also imaged (n=7). Partial saturation sequences were used employing echo time (T/sub E/) of 30, 60 and 120 msec, as well as inversion recovery (TR) sequences. Partial saturation images displayed a homogeneous increase in signal at lesion sites in both bland and hemorrhagic infarcts, reflection prolongation of spin-spin relaxation (T/sub 2/) due to increased tissue water content, blood and edema being indistinguishable. IR images recovered low signal from bland infarcts due to prolongation of spinlattice relaxation (T/sub 1/) by tissue edema, hemorrhagic lesions and short (T/sub 1/) centrally (blood) with moderate or increased IR signal, and low signal peripherally (edema). On follow-up IR imaging, hematomas developed low signal centres, possibly reflection cavitation, with short T/sub 2/ rims, possibly indicating the presence of iron-laden macrophages. In 2 patients with hemorrhagic infarcts an area of increased signal (prolonged T/sub 2/) was seen on initial partial saturation images in the homologous portion of the other hemisphere (normal by CT). This may reflect a local alteration of blood volume or velocity. In 5 patients with old infarcts, a rim of prolonged T/sub 2/ was seen at the periphery of old lesions, possibly reflecting a local chronic increase in extravascular or intravascular water, slowing of blood velocity, or a zone of neuronal dropout. Detailed pathophysiologic correlation is required to understand the basis of these NMR findings.

  15. Monitoring organic reactions by UF-NMR spectroscopy.

    Science.gov (United States)

    Herrera, Antonio; Fernández-Valle, Encarnación; Martínez-Álvarez, Roberto; Molero-Vílchez, Dolores; Pardo-Botero, Zulay D; Sáez-Barajas, Elena

    2015-11-01

    Standard 2D NMR experiments suffer from the many t1 increments needed for spectra with sufficient digital resolution in the indirect dimension. Despite the different methodological approaches to overcome this problem, these increments have prevented studies of fast reactions. The development of ultrafast NMR (UF-NMR) has decisively speeded up the time scale of standard NMR to allow the study of organic reactions as they happen in real time to reveal mechanistic details. This mini-review summarizes the results achieved in monitoring organic reactions through this exciting technique. PMID:25998506

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

    Directory of Open Access Journals (Sweden)

    Luiz H. K. Queiroz Júnior

    2013-01-01

    Full Text Available 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.

  17. 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)

  18. Rotational Doppler Effect and Barnett Field in Spinning NMR

    Science.gov (United States)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  19. Measurement of vorticity diffusion by NMR microscopy.

    Science.gov (United States)

    Brown, Jennifer R; Callaghan, Paul T

    2010-05-01

    In a Newtonian fluid, vorticity diffuses at a rate determined by the kinematic viscosity. Here we use rapid NMR velocimetry, based on a RARE sequence, to image the time-dependent velocity field on startup of a fluid-filled cylinder and therefore measure the diffusion of vorticity. The results are consistent with the solution to the vorticity diffusion equation where the angular velocity on the outside surface of the fluid, at the cylinder's rotating wall, is fixed. This method is a means of measuring kinematic viscosity for low viscosity fluids without the need to measure stress. PMID:20189854

  20. Wideband transmitter for pulse NMR spectrometer

    International Nuclear Information System (INIS)

    A wideband pulse transmitter for NMR excitation in fields of up to 2.4 T (except for 1H, 1F, 203Tl, and 205Tl nuclei) is described. The transmitter provides a pulse power of 400-600 W into a 50-Omega load at frequencies of 2-40 MHz. The transmitter is equipped with a pulse programmer, which allows independent setting, in each of 16 program steps, of pulse durations or pauses of from 10-7 to 103 sec, output powers of from 0 to -63 dB, and a phase of radio-frequency filling of 0 or 1800

  1. Solid state NMR study calcium phosphate ceramics

    International Nuclear Information System (INIS)

    High-resolution 31P and 1H NMR spectra at 40 and 121 MHz 31P and 300 MHz 1H of synthetic and biological samples of calcium phosphates have been obtained by magic angle spinning (MAS) at spinning speeds up to 6.5 kHz, and high power proton decoupling. The samples include crystalline hydroxyapatite, a deficient hydroxyapatite characterized by a Ca/P atomic ratio of 1.5, a poorly crystallized hydroxyapatite, monetite, brushite, octacalcium phosphate, β-tricalcium phosphate and rabbit femoral bone. The interactions between nuclei in unlike structures and the mobility of acid protons are discussed. (author). 11 refs.; 2 figs.; 1 tab

  2. In Vivo Measurements of NMR Relaxation Times

    OpenAIRE

    Kroeker, Randall M.; Mcveigh, Elliot R.; Hardy, Peter; Bronskill, Michael J.; Henkelman, R. Mark

    1985-01-01

    A series of solenoidal NMR probes were built to measure T1 and T2 relaxation times in vivo in the mouse, over the frequency range of 5 to 60 MHz, using inversion-recovery and spin-echo pulse sequences. KHT tumors growing in the legs of C3H mice were studied and compared with normal mouse legs. The tumor relaxation times were studied at 10 MHz during the course of tumor growth and as a function of frequency when the tumor had a mass of approximately 0.9 g. Mouse legs with tumors have higher T1...

  3. Analysis of multiple pulse NMR in solids

    Science.gov (United States)

    Rhim, W.-K.; Elleman, D. D.; Vaughan, R. W.

    1973-01-01

    The general problems associated with the removal of the effects of dipolar broadening from solid-state NMR spectra are analyzed. The effects of finite pulse width and H sub 1 inhomogeneity are shown to have limited the resolution of previous pulse cycles, and a new eight-pulse cycle designed to minimize these problems is discussed. Spectra for F-19 in CaF2 taken with this cycle are presented which show residual linewidth near 10 Hz. The feasibility of measuring proton chemical shift tensors is discussed.

  4. Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy

    International Nuclear Information System (INIS)

    Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis

  5. Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Konuma, Tsuyoshi [Icahn School of Medicine at Mount Sinai, Department of Structural and Chemical Biology (United States); Harada, Erisa [Suntory Foundation for Life Sciences, Bioorganic Research Institute (Japan); Sugase, Kenji, E-mail: sugase@sunbor.or.jp, E-mail: sugase@moleng.kyoto-u.ac.jp [Kyoto University, Department of Molecular Engineering, Graduate School of Engineering (Japan)

    2015-12-15

    Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis.

  6. Study of the production yields of 18F, 11C, 13N and 15O positron emitters from plasma-laser proton sources at ELI-Beamlines for labeling of PET radiopharmaceuticals

    Science.gov (United States)

    Amato, Ernesto; Italiano, Antonio; Margarone, Daniele; Pagano, Benedetta; Baldari, Sergio; Korn, Georg

    2016-03-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of microfluidics labeling approaches. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources such that expected at the ELI-Beamlines facility. 18F, 11C, 13N and 15O production yields were calculated through the TALYS software, by taking into account the broad proton spectra expected. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of 18F-, 11C- and 13N-labeled radiopharmaceuticals exploiting fast and efficient microfluidic labeling systems.

  7. 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.

  8. Insights into oxidation mechanisms in gamma irradiated polypropylene, utilizing selective isotopic labeling with analysis by GC/MS, NMR and FTIR

    International Nuclear Information System (INIS)

    In an effort to shed additional light on the chemical mechanisms underlying the radiation-oxidation of polypropylene, we are using samples having selective C-13 isotopic labeling at the three unique sites within the macromolecular structure. After radiation exposure, we applied gas chromatography/mass spectroscopy (GC/MS), solid-state C-13 NMR, and FTIR to evaluate the applicability of each technique in identifying the molecular labeling of the oxidation products, with the goal of determining the site of origin of the products with respect to the macromolecule. Using GC/MS, we have identified the position of origin of CO2 and CO2 from the polymer. Most of the CO2 (60%) and CO (≥ 90%) come from the C(1) (methylene) position of polypropylene, with (30%) of the CO2 originating from the C(3) (methyl) position, and 10% coming from the C(2) (tertiary) position. By GC/MS we have also identified the labeling patterns in four volatile oxidation products (acetone, methylisobutylketone, isobutane, and methyl acetate), and have used this information to map each compound onto the macromolecular framework. Using NMR we have been able to identify and quantify the time-dependent formation of solid-phase degradation products occurring from post-irradiation aging of polypropylene samples held for 28 months at room temperature in air. Most of the solid oxidation products occur at the C(2) (tertiary) site; the predominant species, C(2) peroxides, increase linearly during about the first 2 years, after which they plateau at a relatively high concentration. (author)

  9. Assignment of the side-chain 1H and 13C resonances of interleukin-1β using double- and triple-resonance heteronuclear three-dimensional NMR spectroscopy

    International Nuclear Information System (INIS)

    The assignment of the aliphatic 1H and 13C resonances of IL-1β, a protein of 153 residues and molecular mass 17.4 kDa, is presented by use of a number of novel three-dimensional (3D) heteronuclear NMR experiments which rely on large heteronuclear one-bond J couplings to transfer magnetization and establish through-bond connectivities. These 3D NMR experiments circumvent problems traditionally associated with the application of conventional 2D 1H-1H correlation experiments to proteins of this size, in particular the extensive chemical shift overlap which precludes the interpretation of the spectra and the reduced sensitivity arising from 1H line widths that are often significantly larger than the 1H-1H J couplings. The assignment proceeds in two stages. In the first step the 13Cα chemical shifts are correlated with the NH and 15N chemical shifts by a 3D triple-resonance NH-15N-13Cα (HNCA) correlation experiment which reveals both intraresidue NH(i)-15N(i)-13Cα(i) and some weaker interresidue NH(i)-15N(i)-Cα(i-1) correlations, the former via intraresidue one-bond 1JNCα and the latter via interresidue two-bond 2HNCα couplings. The second step involves the identification of side-chain spin systems by 3D 1H-13C-13C-1H correlated (HCCH-COSY) and 3D 1H-13C-13C-1H total correlated (HCCH-TOCSY) spectroscopy, the latter making use of isotropic mixing of 13C magnetization to obtain relayed connectivities along the side chains. The authors were able to obtain complete 1H and 13C side-chain assignments for all residues, with the exception of 4 (out of a total of 15) lysine residues for which partial assignments were obtained

  10. NMR study of high-TC superconductors

    International Nuclear Information System (INIS)

    Recent NMR study of high-TC superconductors carried out by Osaka group is reviewed. NQR frequency νQ, Knight shift K, T1 of 63Cu and 17O were measured over a wide hole doping range from light- to heavy-doped systems, LSCO, YBCO, HBCCO, BSCCO, TBCCO and TBCO, together with impurity and pressure effect. By analysing νQ, K and T1, the local hole numbers of Cu and O at the CuO2 plane, n(Cu) and n(O) the relative magnitude of the uniform susceptibility, χ0 and the low-frequency component of the antiferromagnetic spin fluctuations (AFSF), χQ/Γ (χQ is the staggered susceptibility and Γ is the characteristic energy of the spin fluctuation at q=0) are obtained. The relation between n(Cu), n(O) and χQ, χQ/Γ, TC, etc. were discussed. There are optimum values of n(Cu)/2n(O) and n(Cu)+2n(O) to give maximum TC. The NMR results in the superconducting state are well-explained by d-wave pairing model. The result is consistent with the AFSF mediated superconducting model. (orig.)

  11. Nuclear magnetic resonance (NMR)-based metabolomics.

    Science.gov (United States)

    Keun, Hector C; Athersuch, Toby J

    2011-01-01

    Biofluids are by far the most commonly studied sample type in metabolic profiling studies, encompassing blood, urine, cerebrospinal fluid, cell culture media and many others. A number of these fluids can be obtained at a high sampling frequency with minimal invasion, permitting detailed characterisation of dynamic metabolic events. One of the attractive properties of solution-state metabolomics is the ability to generate profiles from these fluids following simple preparation, allowing the analyst to gain a naturalistic, largely unbiased view of their composition that is highly representative of the in vivo situation. Solution-state samples can also be generated from the extraction of tissue or cellular samples that can be tailored to target metabolites with particular properties. Nuclear magnetic resonance (NMR) provides an excellent technique for profiling these fluids and is especially adept at characterising complex solutions. Profiling biofluid samples by NMR requires appropriate preparation and experimental conditions to overcome the demands of varied sample matrices, including those with high protein, lipid or saline content, as well as the presence of water in aqueous samples. PMID:21207299

  12. In vivo NMR spectroscopy of ripening avocado

    International Nuclear Information System (INIS)

    Ripening of avocado fruit is associated with a dramatic increase in respiration. Previous studies have indicated that the increase in respiration is brought about by activation of the glycolytic reaction catalyzing the conversion of fructose-6-phosphate to fructose 1,6-bisphosphate. The authors reinvestigated the proposed role of glycolytic regulation in the respiratory increase using in vivo 31P nuclear magnetic resonance (NMR) spectroscopy using an external surface coil and analysis of phosphofructokinase (PFK), phosphofructophosphotransferase (PFP), and fructose 2,6-bisphosphate (fru 2,6-P2) levels in ripening avocado fruit. In vivo 31P NMR spectroscopy revealed large increases in ATP levels accompanying the increase in respiration. Both glycolytic enzymes, PFK and PFP, were present in avocado fruit, with the latter activity being highly stimulated by fru 2,6-P2. Fructose 2,6-bisphosphate levels increased approximately 90% at the onset of ripening, indicating that the respiratory increase in ripening avocado may be regulated by the activation of PFP brought about by an increase in fru 2,6-P2

  13. Retrobiosynthetic NMR studies with 13C-labeled glucose. Formation of gallic acid in plants and fungi

    International Nuclear Information System (INIS)

    The biosynthesis of gallic acid was studied in cultures of the fungus Phycomyces blakesleeanus and in leaves of the tree Rhus typhina. Fungal cultures were grown with [1-13C]glucose or with a mixture of unlabeled glucose and [U-13C6]glucose. Young leaves of R. typhina were kept in an incubation chamber and were supplied with a solution containing a mixture of unlabeled glucose and [U-13C6]glucose via the leaf stem. Isotope distributions in isolated gallic acid and aromatic amino acids were analyzed by one-dimensional 1H and 13C NMR spectroscopy. A quantitative analysis of the complex isotopomer composition of metabolites was obtained by deconvolution of the 13C13C coupling multiplets using numerical simulation methods. This approach required the accurate analysis of heavy isotope chemical shift effects in a variety of different isotopomers and the analysis of long range 13C13C coupling constants. The resulting isotopomer patterns were interpreted using a retrobiosynthetic approach based on a comparison between the isotopomer patterns of gallic acid and tyrosine. The data show that both in the fungus and in the plant all carbon atoms of gallic acid are biosynthetically equivalent to carbon atoms of shikimate. Notably, the carboxylic group of gallic acid is derived from the carboxylic group of an early intermediate of the shikimate pathway and not from the side chain of phenylalanine or tyrosine. It follows that the committed precursor of gallic acid is an intermediate of the shikimate pathway prior to prephenate or arogenate, most probably 5-dehydroshikimate. A formation of gallic acid via phenylalanine, the lignin precursor, caffeic acid, or 3,4, 5-trihydroxycinnamic acid can be ruled out as major pathways in the fungus and in young leaves of R. typhina. The incorporation of uniformly 13C-labeled glucose followed by quantitative NMR analysis of isotopomer patterns is suggested as a general method for biosynthetic studies. As shown by the plant experiment, this

  14. Rapid prediction of multi-dimensional NMR data sets

    Energy Technology Data Exchange (ETDEWEB)

    Gradmann, Sabine; Ader, Christian [Utrecht University, Faculty of Science, Bijvoet Center for Biomolecular Research (Netherlands); Heinrich, Ines [Max Planck Institute for Molecular Physiology, Department of Physical Biochemistry (Germany); Nand, Deepak [Utrecht University, Faculty of Science, Bijvoet Center for Biomolecular Research (Netherlands); Dittmann, Marc [Max Planck Institute for Molecular Physiology, Department of Physical Biochemistry (Germany); Cukkemane, Abhishek; Dijk, Marc van; Bonvin, Alexandre M. J. J. [Utrecht University, Faculty of Science, Bijvoet Center for Biomolecular Research (Netherlands); Engelhard, Martin [Max Planck Institute for Molecular Physiology, Department of Physical Biochemistry (Germany); Baldus, Marc, E-mail: m.baldus@uu.nl [Utrecht University, Faculty of Science, Bijvoet Center for Biomolecular Research (Netherlands)

    2012-12-15

    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).

  15. Solid state NMR and DFT study of polymer electrolytes

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Brus, Jiří; Dybal, Jiří; Kang, Y. S.

    Linz : Institut für Organische Chemie, Johannes Kepler Universität, 2004 - (Müller, N.). s. 28 [Central European NMR Symposium /6./. 27.09.2004, Linz] R&D Projects: GA AV ČR IAA4050209 Keywords : solid polymer electrolytes * solid state NMR * quantum-chemical DFT calculation Subject RIV: CD - Macromolecular Chemistry

  16. Rapid prediction of multi-dimensional NMR data sets

    International Nuclear Information System (INIS)

    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).

  17. Chemical Equilibrium in Supramolecular Systems as Studied by NMR Spectrometry

    Science.gov (United States)

    Gonzalez-Gaitano, Gustavo; Tardajos, Gloria

    2004-01-01

    Undergraduate students are required to study the chemical balance in supramolecular assemblies constituting two or more interacting species, by using proton NMR spectrometry. A good knowledge of physical chemistry, fundamentals of chemical balance, and NMR are pre-requisites for conducting this study.

  18. 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

    of the primary approaches that were considered. Topics discussed included the future of ultrahigh‐field NMR systems, emerging NMR detection technologies, new approaches to nuclear hyperpolarization, and progress in sample preparation. All of these are orthogonal efforts, whose gains could multiply...... optical measurements. These challenges, and the ways by which scientists and engineers are striving to solve them, are also addressed....

  19. NMR study of phase separation in solutions of linear polymers

    Czech Academy of Sciences Publication Activity Database

    Kouřilová, H.; Šťastná, J.; Hanyková, L.; Spěváček, Jiří

    Poznań : Adam Mickiewicz University, 2010 - (Jurga, S.). s. 27 [AMPERE NMR School. 17.06.2010-26.06.2010, Poznań - Wierzba] R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Keywords : phase separation * polymer solution * NMR Subject RIV: CD - Macromolecular Chemistry

  20. NMR crystallography of active pharmaceuticals ingredients for industrial applications

    Czech Academy of Sciences Publication Activity Database

    Urbanová, Martina; Brus, Jiří; Kobera, Libor

    Herceg Novi : Materials Research Society, 2008. s. 165. [Annual Conference YUCOMAT 2008 /10./. 08.09.2008-12.09.2008, Herceg Novi] R&D Projects: GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : MAS NMR * atorvastatin * NMR crystallography Subject RIV: CF - Physical ; Theoretical Chemistry

  1. What can be expected from NMR in reversed micelles?

    International Nuclear Information System (INIS)

    A review is given of NMR studies on reversed micellar systems since 1970. General principles are emphasized through examples which have led to relevant physico-chemical results in the area. NMR techniques or theories are not detailed in order to focus primarily on the information obtained on the micelles. (author). 50 refs.; 9 figs

  2. Development of portable NMR polarimeter system for polarized HD target

    CERN Document Server

    Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

    2011-01-01

    A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 kg to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.

  3. What can Lattice QCD theorists learn from NMR spectroscopists?

    International Nuclear Information System (INIS)

    Euclidean-time hadron correlation functions computed in Lattice QCD (LQCD) are modeled by a sum of decaying exponentials, reminiscent of the exponentially damped sinusoid models of free induction decay (FID) in Nuclear Magnetic Resonance (NMR) spectroscopy. We present our initial progress in studying how data modeling techniques commonly used in NMR perform when applied to LQCD data

  4. The Characterization of Comblike Polymer Electrolyte by Means of NMR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The comblike polymers based on poly (styrene-co-maleic anhydride) backbone with poly (ethylene glycol) methyl ether as side chains were synthesized and characterized by 1H NMR, with the result compared with that of IR.It is found that it is both feasible and simple to synthesize this kind of compounds with the help of 1H NMR.

  5. Heteronuclear Multidimensional Protein NMR in a Teaching Laboratory

    Science.gov (United States)

    Wright, Nathan T.

    2016-01-01

    Heteronuclear multidimensional NMR techniques are commonly used to study protein structure, function, and dynamics, yet they are rarely taught at the undergraduate level. Here, we describe a senior undergraduate laboratory where students collect, process, and analyze heteronuclear multidimensional NMR experiments using an unstudied Ig domain (Ig2…

  6. Dynamics in solids studied by NMR crystalography and MD simulations

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Šála, Michal; Hodgkinson, P.

    Baveno : -, 2015. s. 20-21. [SMASH 2015. Small Molecule NMR Conference. 20.09.2015-23.09.2015, Baveno] R&D Projects: GA ČR GA15-11223S; GA ČR GA13-24880S Institutional support: RVO:61388963 Keywords : molecular dynamics * calculations of NMR parameters * path integral molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry

  7. Current progress and future prospects in NMR imaging

    International Nuclear Information System (INIS)

    Future prospects in NMR imaging will depend not only on the extent to which images of diagnostic quality can be obtained in reasonable short times, but, more importantly, on whether the whole range of NMR measurements and techniques can be applied to achieve a useful degree of tissue characterization and the measurement of blood flow in vivo. (orig./VJ)

  8. What can Lattice QCD theorists learn from NMR spectroscopists?

    Energy Technology Data Exchange (ETDEWEB)

    George Fleming

    2003-06-01

    Euclidean-time hadron correlation functions computed in Lattice QCD (LQCD) are modeled by a sum of decaying exponentials, reminiscent of the exponentially damped sinusoid models of free induction decay (FID) in Nuclear Magnetic Resonance (NMR) spectroscopy. We present our initial progress in studying how data modeling techniques commonly used in NMR perform when applied to LQCD data.

  9. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.

    Science.gov (United States)

    Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D

    2014-10-01

    An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts. PMID:24946863

  10. Dynamics of solutions and fluid mixtures by NMR

    International Nuclear Information System (INIS)

    After a short introduction to NMR spectroscopy, with a special emphasis on dynamical aspects, an overview on two fundamental aspects of molecular dynamics, NMR relaxation and its relationship with molecular reorientation, and magnetization transfer phenomena induced by molecular rate processes (dynamic NMR) is presented, followed by specific mechanisms of relaxation encountered in paramagnetic systems or with quadrupolar nuclei. Application fields are then reviewed: solvent exchange on metal ions with a variable pressure NMR approach, applications of field gradients in NMR, aggregation phenomena and micro-heterogeneity in surfactant solutions, polymers and biopolymers in the liquid state, liquid-like molecules in rigid matrices and in soft matter (swollen polymers and gels, fluids in and on inorganic materials, food)

  11. $\\beta$-NMR of copper isotopes in ionic liquids

    CERN Multimedia

    We propose to test the feasibility of spin-polarization and $\\beta$-NMR studies on several short-lived copper isotopes, $^{58}$ Cu, $^{74}$Cu and $^{75}$Cu in crystals and liquids. The motivation is given by biological studies of Cu with $\\beta$-NMR in liquid samples, since Cu is present in a large number of enzymes involved in electron transfer and activation of oxygen. The technique is based on spin-polarization via optical pumping in the new VITO beamline. We will use the existing lasers, NMR magnet and NMR chambers and we will prepare a new optical pumping system. The studies will be devoted to tests of achieved $\\beta$-asymmetry in solid hosts, the behaviour of asymmetry when increasing vacuum, and finally NMR scans in ionic liquids. The achieved spin polarization will be also relevant for the plans to measure with high precision the magnetic moments of neutron-rich Cu isotopes.

  12. A nomenclature and data model to describe NMR experiments

    International Nuclear Information System (INIS)

    Despite ongoing efforts in organising NMR information, there is no consistent and well-described generic standard for naming NMR experiments. The main reason for the absence of a universal naming system is that the information content of the coherence pathways is difficult to describe in full detail. We propose a system that describes the common and generic elements of the coherence pathways produced by pulse sequences. The system itself is formalised by an 'NMR experiment protocol' model, which is described in the Universal Modelling Language (UML) as part of the CCPN data model. Furthermore, normalized experiment names can be derived from this proposed model. We hope this article will stimulate discussion to organise the wealth of NMR experiments, and that by bringing this discussion into the public domain we can improve and expand our proposed system to include as much information and as many NMR experiments as possible

  13. Dynamics of antibody domains studied by solution NMR.

    Science.gov (United States)

    Vu, Bang K; Walsh, Joseph D; Dimitrov, Dimiter S; Ishima, Rieko

    2009-01-01

    Information on local dynamics of antibodies is important to evaluate stability, to rationally design variants, and to clarify conformational disorders at the epitope binding sites. Such information may also be useful for improved understanding of antigen recognition. NMR can be used for characterization of local protein dynamics at the atomic level through relaxation measurements. Due to the complexity of the NMR spectra, an extensive use of this method is limited to small protein molecules, for example, antibody domains and some scFv. Here, we describe a protocol that was used to study the dynamics of an antibody domain in solution using NMR. We describe protein preparation for NMR studies, NMR sample optimization, signal assignments, and dynamics experiments. PMID:19252840

  14. NMR screening for rapid protein characterization in structural proteomics.

    Science.gov (United States)

    Hill, Justine M

    2008-01-01

    In the age of structural proteomics when protein structures are targeted on a genome-wide scale, the identification of proteins that are amenable to analysis using x-ray crystallography or NMR spectroscopy is the key to high throughput structure determination. NMR screening is a beneficial part of a structural proteomics pipeline because of its ability to provide detailed biophysical information about the protein targets under investigation at an early stage of the structure determination process. This chapter describes efficient methods for the production of uniformly (15)N-labeled proteins for NMR screening using both conventional IPTG induction and autoinduction approaches in E. coli. Details of sample preparation for NMR and the acquisition of 1D (1)H NMR and 2D (1)H-(15)N HSQC spectra to assess the structural characteristics and suitability of proteins for further structural studies are also provided. PMID:18542882

  15. PI-103增强顺铂对CI3K细胞裸鼠移植瘤生长的抑制作用%PI-103 Enhances Cisplatin-Caused Growth Inhibition of C13K Cell Xenografts in Nude Mice

    Institute of Scientific and Technical Information of China (English)

    刘勇; 孔繁飞; 方勇; 李智敏; 孙淑华

    2013-01-01

    Objective To examine the effect of PI-103 in combination with cisplatin on the proliferation and apoptosis of C13K cells and growth of xenografts of nude mice. Methods The proliferation of C13K cells was assessed by MTT assay after exposure to PI 403, cisplatin or both. Apoptosis was evaluated by flow cytometry. Immunoblot analysis was performed to detect the ex -pression of phosphorylation of AKT and S6 kinase 1. C13K cells was subcutaneously transplanted into nude mice ( n = 16) , which were randomly divided into control group , PI-103 group, cisplatin group and combined treatment group. After treatment for 4 consecutive weeks, the tumor inhibition rate was evaluated. Results PI-103 in combination with cisplatin inhibited the proliferation of C13 K cells in a time-dependent manner. The inhibitory effect of combination therapy was superior to PI 403 or cisplatin treatment alone. PI403 increased cisplatin induced apoptosis in C13K cells. PI403 inhibited the expression of phosphorylation of AKT and S6 kinase 1 in C13K cells. PI-103 plus cisplatin significantly inhibited the growth of xenografts in nude mice and there was significant difference between combined treatment group and cisplatin group. Conclusion PI-103 may enhance growth inhibition of C13K cell xenografts by cisplatin in nude mice.%目的 通过评价PI-103联用顺铂对C13K细胞体外增殖、凋亡及裸鼠移植瘤生长的影响为卵巢癌的靶向治疗寻找新的药物.方法 C13K细胞经PI-103和/或顺铂处理后,以MTT法检测细胞的增殖情况,以流式细胞仪检测细胞凋亡,Western印迹检测p-AKT和p-S6K1的表达情况.建立C13K细胞皮下裸鼠移植瘤模型,随机分成对照组、PI-103组、顺铂组、合并组4组,连续用药4周.观察肿瘤生长情况,计算抑瘤率.结果 PI-103联合顺铂抑制C13K细胞增殖,且随时间延长抑制作用越显著,抑制效果优于单独用药.PI-103可增强顺铂在C13K细胞中引起的凋亡.经PI-103作用后的C13K

  16. Variations of NMR signals by hyperpolarization and ultrasound; Variation von NMR-Signalen durch Hyperpolarisation und Ultraschall

    Energy Technology Data Exchange (ETDEWEB)

    Engelbertz, A.

    2006-07-01

    In this thesis it is described how p-NMR can be applied to metals with verlo low hydrogen concentrations and how a combination of ultrasound and NMR can lead to an improvement of the measureing method. As examples measurements on H{sub 2}O and ethanol are described. (HSI)

  17. A solid state pulsed NMR spectrometer

    International Nuclear Information System (INIS)

    A 10 MHz pulsed NMR spectrometer, built using mostly solid state devices, is described. The pulse programmer provides 2-pulse, 3-pulse, saturation burst and Carr-Purcell sequences both in repetitive and manual modes of operation. The transmitter has a maximum power output of approximately 2 kW with a 75Ω output impedance termination. The total gain of the receiver system is around 120 dB with a minimum band width of 2 MHz. The recovery time of the receiver is approximately 7μsec. A two-channel boxcar integrator capable of working in the single channel, differential and double boxcar modes provides signal to noise ratio improvement. The sensitivity and the linearity of the boxcar integrator are approximately 2 mV and approximately 0.1% respectively. (auth.)

  18. NMR investigations of YMn2Hx hydrides

    International Nuclear Information System (INIS)

    The YMn2Hx hydrides with x = 1, 2, 3 were investigated by 55Mn NMR spin echo measurements at atmospheric and high pressure. Resonance lines at frequencies up to 440 MHz were observed for the hydrides, corresponding to a huge increase of the hyperfine fields at those Mn with hydrogen neighbours. At high pressure the initial decrease of the magnitude of the Mn hyperfine field of YMn2H1 at 4.2 K was found to be 4% per kbar which is an order of magnitude bigger than observed in the other magnetically ordered materials. The effects are interpreted in terms of changes of the orbital contribution and valence electron contribution to the hyperfine field caused by hydrogenation and the influence of the external pressure. (orig.)

  19. Long Lived NMR Signal in Bone

    CERN Document Server

    Zhang, Boyang; Khitrin, Anatoly; Jerschow, Alexej

    2012-01-01

    Solids and rigid tissues such as bone, ligaments, and tendons, typically appear dark in magnetic resonance imaging (MRI), which is due to the extremely short-lived proton nuclear magnetic resonance (NMR) signals. This short lifetime is due to strong dipolar interactions between immobilized proton spins, which render it challenging to detect these signals with sufficient resolution and sensitivity. Here we show the possibility of exciting long-lived signals in cortical bone tissue with a signature consistent with that of bound water signals. Contrary to long-standing belief, it is further shown that dipolar coupling networks are an integral requirement for the excitation of these long-lived signals. The use of these signals could enhance the ability to visualize rigid tissues and solid samples with high sensitivity, resolution, and specificity via MRI.

  20. Experimental implementation of a NMR entanglement witness

    CERN Document Server

    Filgueiras, J G; Auccaise, R E; Vianna, R O; Sarthour, R S; Oliveira, I S

    2012-01-01

    Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage. On this paper it is experimentally analyzed an entanglement witness recently proposed in the context of Nuclear Magnetic Resonance (NMR) experiments to test it in some Bell-diagonal states. We also propose some optimal entanglement witness for Bell-diagonal states. The efficiency of the two types of EW's are compared to a measure of entanglement with tomographic cost, the generalized robustness of entanglement. It is used a GRAPE algorithm to produce an entangled state which is out of the detection region of the EW for Bell-diagonal states. Upon relaxation, the results show that there is a region in which both EW fails, whereas the generalized robustness still shows entanglement, but with the entanglement witness proposed here with a better performance.

  1. NMR spectroscopy assists synthetic fuels research

    International Nuclear Information System (INIS)

    There is little doubt that sources of liquid transport fuels, other than petroleum, will need to be developed for the future. While coal, oil shale and natural gas are potentially appropriate hydrocarbon resources, they all require chemical processing before a substitute crude oil (or synfuel) can be produced. There are many different possible pathways by which alternative crudes can be produced and subsequently upgraded to transport fuel quality. To develop and evaluate processing strategies it is necessary to gain some understanding of the nature of feedstocks, catalysts, process intermediates and potential final products. Nuclear Magnetic Resonance (NMR) spectroscopy has proven a useful and versatile technique for this purpose. Some contributions from this technique to coal and gas conversion research are illustrated and discussed

  2. Two-Dimensional NMR Lineshape Analysis.

    Science.gov (United States)

    Waudby, Christopher A; Ramos, Andres; Cabrita, Lisa D; Christodoulou, John

    2016-01-01

    NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions. PMID:27109776

  3. Spatially resolved spectroscopy using tapered stripline NMR

    Science.gov (United States)

    Tijssen, Koen C. H.; Bart, Jacob; Tiggelaar, Roald M.; Janssen, J. W. G. (Hans); Kentgens, Arno P. M.; van Bentum, P. Jan M.

    2016-02-01

    Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10-2-101 s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.

  4. Carbon-13 NMR studies of liquid crystals

    International Nuclear Information System (INIS)

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

  5. NMR study of hyper-polarized 129Xe and applications to liquid-phase NMR experiments

    International Nuclear Information System (INIS)

    In liquid samples where both nuclear polarization and spin density are strong, the magnetization dynamics, which can be analysed by NMR (nuclear magnetic resonance) methods, is deeply influenced by the internal couplings induced by local dipolar fields. The present thesis describes some of the many consequences associated to the presence in the sample of concentrated xenon hyper-polarized by an optical pumping process. First, we deal with the induced modifications in frequency and line width of the proton and xenon spectra, then we present the results of SPIDER, a coherent polarization transfer experiment designed to enhance the polarization of protons, in order to increase their NMR signal level. A third part is dedicated to the description of the apparition of repeated chaotic maser emissions by un unstable xenon magnetization coupled to the detection coil tuned at the xenon Larmor frequency (here 138 MHz). In the last part, we present a new method allowing a better tuning of any NMR detection probe and resulting in sensible gains in terms of sensitivity and signal shaping. Finally, we conclude with a partial questioning of the classical relaxation theory in the specific field of highly polarized and concentrated spin systems in a liquid phase. (author)

  6. Temperature-dependent sensitivity enhancement of solid-state NMR spectra of α-synuclein fibrils

    International Nuclear Information System (INIS)

    The protein α-synuclein (AS) is the primary fibrillar component of Lewy bodies, the pathological hallmark of Parkinson's disease. Wild-type human AS and the three mutant forms linked to Parkinson's disease (A53T, A30P, and E46K) all form fibrils through a nucleation-dependent pathway; however, the biophysical details of these fibrillation events are not yet well understood. Atomic-level structural insight is required in order to elucidate the potential role of AS fibrils in Parkinson's disease. Here we show that low temperature acquisition of magic-angle spinning NMR spectra of wild type AS fibrils-greatly enhances spectral sensitivity, enabling the detection of a substantially larger number of spin systems. At 0 ± 3 deg. C sample temperature, cross polarization (CP) experiments yield weak signals. Lower temperature spectra (-40 ± 3 deg. C) demonstrated several times greater signal intensity, an effect further amplified in 3D 15N-13C-13C experiments, which are required to perform backbone assignments on this sample. Thus 3D experiments enabled assignments of most amino acids in the rigid part of the fibril (approximately residues 64 to 94), as well as tentative site-specific assignments for T22, V26, A27, Y39, G41, S42, H50, V52, A53, T54, V55, V63, A107, I112, and S129. Most of these signals were not observed in 2D or 3D spectra at 0 ± 3 deg. C. Spectra acquired at low temperatures therefore permitted more complete chemical shift assignments. Observation of the majority of residues in AS fibrils represents an important step towards solving the 3D structure

  7. Quantum Mechanical Nature in Liquid NMR Quantum Computing

    Institute of Scientific and Technical Information of China (English)

    LONGGui-Lu; YANHai-Yang; 等

    2002-01-01

    The quantum nature of bulk ensemble NMR quantum computing-the center of recent heated debate,is addressed.Concepts of the mixed state and entanglement are examined,and the data in a two-qubit liquid NMR quantum computation are analyzed.the main points in this paper are;i) Density matrix describes the "state" of an average particle in an ensemble.It does not describe the state of an individual particle in an ensemble;ii) Entanglement is a property of the wave function of a microscopic particle(such as a molecule in a liquid NMR sample),and separability of the density matrix canot be used to measure the entanglement of mixed ensemble;iii) The state evolution in bulkensemble NMR quantum computation is quantum-mechanical;iv) The coefficient before the effective pure state density matrix,ε,is a measure of the simultaneity of the molecules in an ensemble,It reflets the intensity of the NMR signal and has no significance in quantifying the entanglement in the bulk ensemble NMR system.The decomposition of the density matrix into product states is only an indication that the ensemble can be prepared by an ensemble with the particles unentangeld.We conclude that effective-pure-state NMR quantum computation is genuine,not just classical simulations.

  8. High-resolution NMR spectroscopy under the fume hood.

    Science.gov (United States)

    Küster, Simon K; Danieli, Ernesto; Blümich, Bernhard; Casanova, Federico

    2011-08-01

    This work reports the possibility to acquire high-resolution (1)H NMR spectra with a fist-sized NMR magnet directly installed under the fume hood. The small NMR sensor based on permanent magnets was used to monitor the trimerization of propionaldehyde catalyzed by indium trichloride in real time by continuously circulating the reaction mixture through the magnet bore in a closed loop with the help of a peristaltic pump. Thanks to the chemical selectivity of NMR spectroscopy the progress of the reaction can be monitored on-line by determining the concentrations of both reactant and product from the area under their respective lines in the NMR spectra as a function of time. This in situ measurement demonstrates that NMR probes can be used in chemistry laboratories, e.g. for reaction optimization, or installed at specific points of interest along industrial process lines. Therefore, it will open the door for the implementation of feedback control based on spectroscopic NMR data. PMID:21698335

  9. Molecular dynamics simulations on PGLa using NMR orientational constraints

    International Nuclear Information System (INIS)

    NMR data obtained by solid state NMR from anisotropic samples are used as orientational constraints in molecular dynamics simulations for determining the structure and dynamics of the PGLa peptide within a membrane environment. For the simulation the recently developed molecular dynamics with orientational constraints technique (MDOC) is used. This method introduces orientation dependent pseudo-forces into the COSMOS-NMR force field. Acting during a molecular dynamics simulation these forces drive molecular rotations, re-orientations and folding in such a way that the motional time-averages of the tensorial NMR properties are consistent with the experimentally measured NMR parameters. This MDOC strategy does not depend on the initial choice of atomic coordinates, and is in principle suitable for any flexible and mobile kind of molecule; and it is of course possible to account for flexible parts of peptides or their side-chains. MDOC has been applied to the antimicrobial peptide PGLa and a related dimer model. With these simulations it was possible to reproduce most NMR parameters within the experimental error bounds. The alignment, conformation and order parameters of the membrane-bound molecule and its dimer were directly derived with MDOC from the NMR data. Furthermore, this new approach yielded for the first time the distribution of segmental orientations with respect to the membrane and the order parameter tensors of the dimer systems. It was demonstrated the deuterium splittings measured at the peptide to lipid ratio of 1/50 are consistent with a membrane spanning orientation of the peptide

  10. Molecular dynamics simulations on PGLa using NMR orientational constraints

    Energy Technology Data Exchange (ETDEWEB)

    Sternberg, Ulrich, E-mail: ulrich.sternberg@partner.kit.edu; Witter, Raiker [Tallinn University of Technology, Technomedicum (Estonia)

    2015-11-15

    NMR data obtained by solid state NMR from anisotropic samples are used as orientational constraints in molecular dynamics simulations for determining the structure and dynamics of the PGLa peptide within a membrane environment. For the simulation the recently developed molecular dynamics with orientational constraints technique (MDOC) is used. This method introduces orientation dependent pseudo-forces into the COSMOS-NMR force field. Acting during a molecular dynamics simulation these forces drive molecular rotations, re-orientations and folding in such a way that the motional time-averages of the tensorial NMR properties are consistent with the experimentally measured NMR parameters. This MDOC strategy does not depend on the initial choice of atomic coordinates, and is in principle suitable for any flexible and mobile kind of molecule; and it is of course possible to account for flexible parts of peptides or their side-chains. MDOC has been applied to the antimicrobial peptide PGLa and a related dimer model. With these simulations it was possible to reproduce most NMR parameters within the experimental error bounds. The alignment, conformation and order parameters of the membrane-bound molecule and its dimer were directly derived with MDOC from the NMR data. Furthermore, this new approach yielded for the first time the distribution of segmental orientations with respect to the membrane and the order parameter tensors of the dimer systems. It was demonstrated the deuterium splittings measured at the peptide to lipid ratio of 1/50 are consistent with a membrane spanning orientation of the peptide.

  11. 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.

  12. Understanding NMR relaxometry of partially water-saturated rocks

    Directory of Open Access Journals (Sweden)

    O. Mohnke

    2014-11-01

    Full Text Available Nuclear Magnetic Resonance (NMR relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. These assessments are based on the proportionality of NMR signal amplitude and relaxation time to porosity (water content and pore size, respectively. The relationship between pore size and NMR relaxation time depends on pore shape, which is usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks differs strongly from the response calculated for spherical or cylindrical pores, because these pore shapes cannot account for water menisci remaining in the corners of de-saturated angular pores. Therefore, we consider a bundle of pores with triangular cross-sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of de-saturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions. For this pore model, NMR amplitude and NMR relaxation time at partial water saturation strongly depend on pore shape even so the NMR relaxation time at full saturation only depends on the surface to volume ratio of the pore. The pore-shape-dependence at partial saturation arises from the pore shape and capillary pressure dependent water distribution in pores with triangular cross-sections. Moreover, we show the qualitative agreement of the saturation dependent relaxation time distributions of our model with those observed for rocks and soils.

  13. Developments of RF Coil for P in vivo NMR Spectroscopy .

    Directory of Open Access Journals (Sweden)

    S. Khushu

    1993-07-01

    Full Text Available RF receiver coils are very important parts of an NMR System. The design of these coils is very critical and has a dramatic effect on the SNR of the NMR signal and are generally developed in TRA/REC mode. This paper reports the developments of a 3.5 cm TRA/REC 26 MHz RF coil for P spectroscopy of small organs like thyroid. The coil is small in size, fits well in the neck for thyroid spectroscopy and is successfully working with the 1.5 tesla whole body Superconducting NMR System available at INMAS.

  14. Developments of RF Coil for P in vivo NMR Spectroscopy .

    OpenAIRE

    S. Khushu; S.B. Mehta; Sushil Chandra; A Jena

    1993-01-01

    RF receiver coils are very important parts of an NMR System. The design of these coils is very critical and has a dramatic effect on the SNR of the NMR signal and are generally developed in TRA/REC mode. This paper reports the developments of a 3.5 cm TRA/REC 26 MHz RF coil for P spectroscopy of small organs like thyroid. The coil is small in size, fits well in the neck for thyroid spectroscopy and is successfully working with the 1.5 tesla whole body Superconducting NMR System availab...

  15. Superparamagnetic particles as possible contrast agents for NMR imaging

    International Nuclear Information System (INIS)

    The development of 'magneto-pharmaceuticals' plays an important role in the extension of nuclear magnetic resonance (NMR) for diagnostic medicine. Fundamental investigations leading to the new area of NMR contrast agents are considered. Superparamagnetic particles represent a new class of NMR contrast agents that usually referred to as T2 or T*2 contrast agents as opposed to T1 agents, such as paramagnetic chelates. Another novelty presented by superparamagnetic agents is their specific distribution. The synthesis and the transverse R2 and longitudinal R1 relaxivity measurements of some ferro-, ferri- and superparamagnetic particles suspensions are presented. (authors)

  16. Molecular dynamics computer simulations based on NMR data

    International Nuclear Information System (INIS)

    In the work described in this thesis atom-atom distance information obtained from two-dimensional cuclear magnetic resonance is combined with molecular dynamics simulaitons. The simulation is used to improve the accuracy of a structure model constructed on the basis of NMR data. During the MD refinement the crude NMR structure is simultaneously optimized with respect to the atomic interaction function and to the set of atom-atom distances or other NMR information. This means that insufficient experimental data is completed with theoretical knowledge and the combination will lead to more reliable structures than would be obtained from one technique alone. (author). 191 refs.; 17 figs.; 12 schemes; 22 tabs

  17. Room Temperature Chiral Discrimination in Paramagnetic NMR Spectroscopy

    Science.gov (United States)

    Soncini, Alessandro; Calvello, Simone

    2016-04-01

    A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization P rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. 140, 011103 (2014)] is generalized here to paramagnetic systems. Our theory predicts new contributions to P , varying as the square of the inverse temperature. Ab initio calculations for ten Dy3 + complexes, at 293 K, show that, in strongly anisotropic paramagnetic molecules, P can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.

  18. Holographic reconstruction of NMR images in Fresnel transform technique

    International Nuclear Information System (INIS)

    The free induction signal in the NMR Fresnel transform imaging technique is expressed by a similar equation to that of the Fresnel diffraction equation in light. It is possible to record NMR signals on a photographic film as a hologram in the same manner as optical holography. Since the dynamic range of the signal in the Fresnel transform technique is small, image information can be recorded on a hologram at a high efficiency. Very clear images are reconstructed optically from the NMR hologram in many experiments. Image brightness are improved by using a compound hologram in which several same holograms are arranged periodically. (author)

  19. A simple low-cost single-crystal NMR setup

    Science.gov (United States)

    Vinding, Mads S.; Kessler, Tommy O.; Vosegaard, Thomas

    2016-08-01

    A low-cost single-crystal NMR kit is presented along with a web-based post-processing software. The kit consists of a piezo-crystal motor and a goniometer for the crystal, both embedded in a standard wide-bore NMR probe with a 3D printed scaffold. The NMR pulse program controls the angle setting automatically, and the post-processing software incorporates a range of orientation-angle discrepancies present in the kit and other single-crystal setups. Results with a NaNO3 single-crystal show a high degree of reproducibility and excellent agreement with previous findings for the anisotropic quadrupolar interaction.

  20. Room temperature chiral discrimination in paramagnetic NMR spectroscopy

    CERN Document Server

    Soncini, Alessandro

    2016-01-01

    A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization $\\mathbf{P}$ rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. $\\mathbf{140}$, 011103 (2014)], is here generalized to paramagnetic systems. Our theory predicts new contributions to $\\mathbf{P}$, varying as the square of the inverse temperature. Ab initio calculations for ten Dy$^{3+}$ complexes, at 293K, show that in strongly anisotropic paramagnetic molecules $\\mathbf{P}$ can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.

  1. Structural biology applications of solid state MAS DNP NMR

    Science.gov (United States)

    Akbey, Ümit; Oschkinat, Hartmut

    2016-08-01

    Dynamic Nuclear Polarization (DNP) has long been an aim for increasing sensitivity of nuclear magnetic resonance (NMR) spectroscopy, delivering spectra in shorter experiment times or of smaller sample amounts. In recent years, it has been applied in magic angle spinning (MAS) solid-state NMR to a large range of samples, including biological macromolecules and functional materials. New research directions in structural biology can be envisaged by DNP, facilitating investigations on very large complexes or very heterogeneous samples. Here we present a summary of state of the art DNP MAS NMR spectroscopy and its applications to structural biology, discussing the technical challenges and factors affecting DNP performance.

  2. GC-MS and NMR analysis of the bioactive compounds from the crude extracts of Waltheria indica and the histopathological changes induced in albino rats challenged with Naja nigricollis venom

    Directory of Open Access Journals (Sweden)

    Philip Ilani

    2016-05-01

    Full Text Available Objective: To develop a characteristic fingerprint of the different chemical compounds of plant by gas chromatography-mass spectrometer (GC-MS and nuclear magnetic resonance (NMR analysis and assess the effect of the crude extract on histological changes induced in Naja nigricollis (N. nigricollis envenomed albino rats. Methods: The coarsely powdered Waltheria indica (W. indica whole plant material was extracted using 70% methanol. GC-MS analysis was carried out using a Shimadzu GC-MS QP 2010 plus system of gas chromatography interfaced to a mass spectrometer. The identification of components was based on National Institute of Standard and Technology-08 and Willey-8 libraries. Hydrogen-NMR spectra of the extracts was performed using Bruker Biospin Avance 400-MHz NMR spectrophotometer with a 5 mm broad inverse probe head, equipped with shielded z-gradient accessories and C-13 NMR hetero-nuclear single quantum correction was carried out using the Brucker’s standard pulse library. The efficacy of the crude extract of W. indica whole plant was tested and the lesions induced in the liver, brain and kidney of albino rats challenged with N. nigricollis were analyzed by light microscopy. Results: The identification of the bioactive compounds from W. indica by GC-MS analysis revealed 41 peaks. A total of 38 compounds were identified with majority having important pharmacological activities that included anti-microbial, anti-cancer, anti-oxidant antiinflammatory, anti-allergenic, anti-ageing, anti-arthritic, larvicidal, anti-convulsant and herbicidal activities. C-13 and hydrogen-NMR analysis of W. indica elucidated key bioactive compounds in the whole plant that were consistent with the classes of bioactive compounds detected by GC-MS analysis. The efficacy of the crude extract of W. indica whole plant in ameliorating histopathological lesions induced in the liver, brain and kidney of albino rats challenged with N. nigricollis venom revealed the

  3. GC-MS and NMR analysis of the bioactive compounds from the crude extracts ofWaltheria indica and the histopathological changes induced in albino rats challenged withNaja nigricollis venom

    Institute of Scientific and Technical Information of China (English)

    Philip Ilani; Nicholas Ajodo; Folashade Adewusi; Samirat Yakubu; Victor Yakubu Cosmos; Ache Eunice; Atonila Kayode Ezekiel; Oshiedu Sarah; Emmanuel Amlabu

    2016-01-01

    Objective:To develop a characteristic fingerprint of the different chemical compounds of plant by gas chromatography-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR) analysis and assess the effect of the crude extract on histological changes induced inNaja nigricollis(N. nigricollis)envenomed albino rats. Methods: The coarsely powderedWaltheria indica (W. indica) whole plant material was extracted using 70% methanol.GC-MS analysis was carried out using a ShimadzuGC-MS QP 2010 plus system of gas chromatography interfaced to a mass spectrometer. The identification of components was based on National Institute of Standard and Technology-08 and Willey-8 libraries. Hydrogen-NMR spectra of the extracts was performed using Bruker Biospin Avance 400-MHzNMR spectrophotometer with a 5 mm broad inverse probe head, equipped with shielded z-gradient accessories andC-13 NMR hetero-nuclear single quantum correction was carried out using the Brucker’s standard pulse library. The efficacy of the crude extract ofW. indica whole plant was tested and the lesions induced in the liver, brain and kidney of albino rats challenged withN. nigricollis were analyzed by light microscopy. Results:The identification of the bioactive compounds fromW. indica byGC-MS analysis revealed 41 peaks. A total of 38 compounds were identified with majority having important pharmacological activities that included anti-microbial, anti-cancer, anti-oxidant anti-inflammatory, anti-allergenic, anti-ageing, anti-arthritic, larvicidal, anti-convulsant and herbicidal activities.C-13 and hydrogen-NMR analysis ofW. indica elucidated key bioactive compounds in the whole plant that were consistent with the classes of bioactive compounds detected byGC-MS analysis. The efficacy of the crude extract ofW. indica whole plant in ameliorating histopathological lesions induced in the liver, brain and kidney of albino rats challenged withN. nigricollis venom revealed the abrogation of tissue degeneration when

  4. NMR Methods, Applications and Trends for Groundwater Evaluation and Management

    Science.gov (United States)

    Walsh, D. O.; Grunewald, E. D.

    2011-12-01

    Nuclear magnetic resonance (NMR) measurements have a tremendous potential for improving groundwater characterization, as they provide direct detection and measurement of groundwater and unique information about pore-scale properties. NMR measurements, commonly used in chemistry and medicine, are utilized in geophysical investigations through non-invasive surface NMR (SNMR) or downhole NMR logging measurements. Our recent and ongoing research has focused on improving the performance and interpretation of NMR field measurements for groundwater characterization. Engineering advancements have addressed several key technical challenges associated with SNMR measurements. Susceptibility of SNMR measurements to environmental noise has been dramatically reduced through the development of multi-channel acquisition hardware and noise-cancellation software. Multi-channel instrumentation (up to 12 channels) has also enabled more efficient 2D and 3D imaging. Previous limitations in measuring NMR signals from water in silt, clay and magnetic geology have been addressed by shortening the instrument dead-time from 40 ms to 4 ms, and increasing the power output. Improved pulse sequences have been developed to more accurately estimate NMR relaxation times and their distributions, which are sensitive to pore size distributions. Cumulatively, these advancements have vastly expanded the range of environments in which SNMR measurements can be obtained, enabling detection of groundwater in smaller pores, in magnetic geology, in the unsaturated zone, and nearby to infrastructure (presented here in case studies). NMR logging can provide high-resolution estimates of bound and mobile water content and pore size distributions. While NMR logging has been utilized in oil and gas applications for decades, its use in groundwater investigations has been limited by the large size and high cost of oilfield NMR logging tools and services. Recently, engineering efforts funded by the US Department of

  5. 13C-NMR of diterpenes with pimarane skeleton

    International Nuclear Information System (INIS)

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

  6. Structure and dynamics of model membranes by advanced NMR spectroscopy

    International Nuclear Information System (INIS)

    The molecular conformation and dynamics of phospholipids have important implications for the detailed understanding of membrane function, fluidity, composition and protein-lipid interaction. The advanced nuclear magnetic resonance (NMR) methods used in the study of structure and dynamics of model membranes are reviewed. Conformational exchange of the lipid headgroup as well as segmental order can be measured using dipolar couplings between the nuclei 31 P - 1 H, 13 C - 1 H, 1 H - 1 H and 31 P - 13 C by a novel solid-state two-dimensional (2D) NMR technique. Self-diffusion of lipids and water in lipid bilayers measured by sensitive NMR method of fringe field of superconducting magnet as well as 2D deuterium exchange NMR spectroscopy are presented. The powerful method of 2D NOESY in establishing the intermolecular interaction between an antineoplastic drug (daunomycin) and a model membrane is discussed. (authors)

  7. Mobile NMR for geophysical analysis and materials testing

    Institute of Scientific and Technical Information of China (English)

    BLUMICH Bernhard; MAULER Jǒrg; HABER Agnes; PERLO Juan; DANIELI Ernesto; CASANOVA Federico

    2009-01-01

    Initiated by well logging NMR, portable NMR instruments are being developed for a variety of novel applications in materials testing, process analysis and control, which provides new opportunities for geophysical investigations. Small-diameter cylindrical sensors can probe short distances into the walls of slim-line logging holes, and single-sided sensors enable non-destructive testing of large objects. Both sensors are characterized by small sensitive volumes. Barrel-shaped magnets that accommodate the sample in their center have higher sensitivity due to a larger sensitive volume but can accommodate only samples like drill cores, which fit in size to the diameter of the magnet bore. Both types of magnets can be scaled down to the size of a coffee mug to arrive at sub-compact NMR equipment. Portable NMR magnets are reviewed in the context of applications related to geophysics.

  8. NMR methods for the investigation of structure and transport

    International Nuclear Information System (INIS)

    Extensive derivations of required fundamental relations for readers with engineering background New applications based on MRI, PGSE-NMR, and low-field NMR New concepts in quantitative data evaluation and image analysis Methods of nuclear magnetic resonance (NMR) are increasingly applied in engineering sciences. The book summarizes research in the field of chemical and process engineering performed at the Karlsruhe Institute of Technology (KIT). Fundamentals of the methods are exposed for readers with an engineering background. Applications cover the fields of mechanical process engineering (filtration, solid-liquid separation, powder mixing, rheometry), chemical process engineering (trickle-bed reactor, ceramic sponges), bioprocess engineering (biofilm growth), and food process engineering (microwave heating, emulsions). Magnetic Resonance Imaging (MRI) as well as low-field NMR are covered with notes on hardware. Emphasis is placed on quantitative data analysis and image processing. (orig.)

  9. Isotope labeling strategies for NMR studies of RNA

    International Nuclear Information System (INIS)

    The known biological functions of RNA have expanded in recent years and now include gene regulation, maintenance of sub-cellular structure, and catalysis, in addition to propagation of genetic information. As for proteins, RNA function is tightly correlated with structure. Unlike proteins, structural information for larger, biologically functional RNAs is relatively limited. NMR signal degeneracy, relaxation problems, and a paucity of long-range 1H-1H dipolar contacts have limited the utility of traditional NMR approaches. Selective isotope labeling, including nucleotide-specific and segmental labeling strategies, may provide the best opportunities for obtaining structural information by NMR. Here we review methods that have been developed for preparing and purifying isotopically labeled RNAs, as well as NMR strategies that have been employed for signal assignment and structure determination.

  10. 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

    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...

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

    International Nuclear Information System (INIS)

    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

  12. Analysis of human urine metabolites using SPE and NMR spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nuclear magnetic resonance (NMR) spectroscopic analysis of metabonome/metabolome has widespread applications in biomedical science researches. However, most of NMR resonances for urinary metabolites remain to be fully assigned. In the present study, human urine samples from two healthy volunteers were pre-treated with C18 solid-phase extraction and the resultant 5 sub-fractions were subjected to one- and two-dimensional NMR studies, including 1H J-Resolved, 1H-1H COSY, 1H-1H TOCSY, 1H-13C HSQC, and HMBC 2D NMR. More than 70 low molecular weight metabolites were identified, and complete assignments of 1H and 13C resonances including many complex coupled spin systems were obtained.

  13. Solution NMR studies of polytopic α-helical membrane proteins.

    Science.gov (United States)

    Nietlispach, Daniel; Gautier, Antoine

    2011-08-01

    NMR spectroscopy has established itself as one of the main techniques for the structural study of integral membrane proteins. Remarkably, over the last few years, substantial progress has been achieved in the structure determination of increasingly complex polytopical α-helical membrane proteins, with their size approaching ∼100kDa. Such advances are the result of significant improvements in NMR methodology, sample preparation and powerful selective isotope labelling schemes. We review the requirements facilitating such work based on the more recent solution NMR studies of α-helical proteins. While the majority of such studies still use detergent-solubilized proteins, alternative more native-like lipid-based media are emerging. Recent interaction, dynamics and conformational studies are discussed that cast a promising light on the future role of NMR in this important and exciting area. PMID:21775128

  14. Recent progress in protein structure analysis by NMR spectroscopy

    International Nuclear Information System (INIS)

    In recent years, many NMR methodologies have been developed to improve the molecular weight limit of protein structure analysis. Sophisticated selective stable-isotope labeling techniques such as the SAIL method solved the issue of signal reduction due to increased correlation time and that of spectral overlapping. Residual dipolar coupling and paramagnetic relaxation enhancement enabled to obtain long-range distance restraints for structure determination. NMR analysis of intrinsically disordered protein revealed novel molecular recognition mode of protein called coupling folding and binding. NMR method also revealed intermediates in macromolecular binding processes. New data acquisition techniques such the projection spectroscopy and the non-linear sampling, which introduced signal processing techniques, were developed to reduce the data acquisition time and/or increase sensitivity. In this chapter, recent progress in protein structure analysis by NMR spectroscopy is summarized. (author)

  15. NMR study of some coumarins and furocoumarins methylated

    Science.gov (United States)

    Miranda, R.; Santana, L.; Uriarte, E.; Zagotto, G.

    1994-01-01

    The 1H and 13C NMR spectra of various methylcoumarins and methylfurocoumarins are reported. All signals were assigned and the influence on chemical shifts of methylation at various positions was determined.

  16. NMR methods for the investigation of structure and transport

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Edme H. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Mechanische Verfahrenstechnik und Mechanik

    2012-07-01

    Extensive derivations of required fundamental relations for readers with engineering background New applications based on MRI, PGSE-NMR, and low-field NMR New concepts in quantitative data evaluation and image analysis Methods of nuclear magnetic resonance (NMR) are increasingly applied in engineering sciences. The book summarizes research in the field of chemical and process engineering performed at the Karlsruhe Institute of Technology (KIT). Fundamentals of the methods are exposed for readers with an engineering background. Applications cover the fields of mechanical process engineering (filtration, solid-liquid separation, powder mixing, rheometry), chemical process engineering (trickle-bed reactor, ceramic sponges), bioprocess engineering (biofilm growth), and food process engineering (microwave heating, emulsions). Magnetic Resonance Imaging (MRI) as well as low-field NMR are covered with notes on hardware. Emphasis is placed on quantitative data analysis and image processing. (orig.)

  17. Optical analogue of 2D heteronuclear double-quantum NMR

    CERN Document Server

    Tollerud, Jonathan

    2016-01-01

    Heteronuclear multi-quantum spectroscopy is a powerful part of the NMR toolbox, commonly used to identify specific sequences of atoms in complex pulse sequences designed to determine the structure of complex molecules, including proteins. Optical coherent multidimensional spectroscopy (CMDS) is analogous to multidimensional NMR and many of the techniques of NMR have been adapted for application in the optical regime. This has been highly successful, with CMDS being used to understand energy transfer in photosynthesis and many body effects in semiconductor nanostructures amongst many other scientific breakthroughs. Experimental challenges have, however, prevented the translation of heteronuclear multi-quantum NMR to the optical regime, where capabilities to isolate signals in otherwise congested spectra, reduce acquisition times and enable more incisive probes of multi-particle correlations and complex electronic systems would have great benefit. Here we utilise a diffraction based pulseshaper to impose the tw...

  18. NMR - from basic physics to images of the human body

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) is a remarkable phenomenon which involves the exchange of very weak radio frequency radiation between atomic nuclei and a sensitive detecting apparatus. It was originally regarded as a rather esoteric effect of great theoretical interest, but has since proved to have an amazing range of applications over many scientific disciplines, including nuclear physics, solid state physics, all branches of chemistry, biochemistry, physiology and most recently in medical diagnosis. In this Discourse the principles of NMR and trace briefly the history of its applications are examined and illustrated. Headings are: early history; nuclear resonance; relaxation time; the chemical shift; spin-spin coupling (NMR spectra); chemical shifts in biological tissue; NMR imaging; conclusions. (author)

  19. 31P NMR Study on Some Phosphorus-Containing Compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    31P NMR has become a widely applied spectroscopic probe of the structure of phosphorus-containing compounds. Meanwhile, the application of 31P NMR has been rapidly expanded to biochemistry and medicinal chemistry of phosphorus-containing compounds because the growing importance of the phosphorus compounds is now widely realized. We report here the results of 31P NMR study on some phosphorus-containing compounds, namely, O-alkyl O-4-nitrophenyl methyl phosphonates with different alkyl chain-length (MePO-n), 4-nitrophenyl alkylphenylphosphinates with different alkyl chain-length (PhP-n), diethyl phosphono- acetonitrile anion and diethyl phosphite anion . Our results indicate that 31P NMR can not only be applied to not only the study of the hydrolytic reactions of MePO-8 and PhP-8 but also be applied to the study of the presence of the anions of diethylphosphonoacetonitrile and diethyl phosphite in nucleophilic reactions.

  20. 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: 1.179, year: 2014

  1. 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.

  2. A multinuclear static NMR study of geopolymerisation

    International Nuclear Information System (INIS)

    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 23Na, 27Al and 29Si 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

  3. NMR studies of the exocyclic 1,N6-ethenodeoxyadenosine adduct (εdA) opposite thymidine in a DNA duplex. Nonplanar alignment of εdA(anti) and dT(anti) at the lesion site

    International Nuclear Information System (INIS)

    Two-dimensional proton NMR studies are reported on the complementary d(C-A-T-G-T-G-T-A-C)·d(G-T-A-C-εA-C-A-T-G) nonanucleotide duplex (designated εdA·dT 9-mer duplex) containing 1,N6-ethenodeoxyadenosine (εdA), a carcinogen-DNA adduct, positioned opposite thymidine in the center of the helix. The authors NMR studies have focused on the conformation of the εdA·dT 9-mer duplex at neutral pH with emphasis on defining the alignment at the dT5·εdA14 lesion site. The through-space NOE distance connectivities establish that both dT5 and εdA14 adopt anti glycosidic torsion angles, are directed into the interior of the helix, and stack with flanking Watson-Crick dG4·dC15 and dG6·dC13 pairs. Furthermore, the d(G4-T5-G6)·d(C13-εA14-C15) trinucleotide segment centered about the dT5·εdA14 lesion site adopts a right-handed helical conformation in solution. Energy minimization computations were undertaken starting from six different alignments of dT5(anti) and εdA14(anti) at the lesion site and were guided by distance constraints defined by lower and upper bounds estimated from NOESY data sets on the εdA·dT 9-mer duplex. The NMR data are consistent with a nonplanar alignment of εdA14(anti) and dT5(anti) with dT5 displaced toward the flanking dG4·dC15 base pair within the d(G4-T5-G6)·d(C13-εA14-C15) segment of the εdA·dT 9-mer duplex

  4. 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: 3.840, year: 2014 http://pubs.rsc.org/en/content/articlepdf/2015/ra/c4ra14404j

  5. NMR at the frontier of pulsed high field magnets

    International Nuclear Information System (INIS)

    The first 1H, 2D, 63Cu NMR experiments in pulsed high field magnets are reported. The resonances were observed near the field maximum. Examples at field strengths up to 46 T are shown. The experimental set-up and strategies for calibrating the magnets will be discussed. The obtainable signal-to-noise and resolution shows that NMR in pulsed high field magnets is able to become a valuable research tool

  6. Laundering and Deinking Applications of 1H NMR Imaging

    Science.gov (United States)

    Tutunjian, P. N.; Borchardt, J. K.; Prieto, N. E.; Raney, K. H.; Ferris, J. A.

    One-dimensional 1H NMR imaging techniques are used to visualize oil removal from fabrics and paper fibers immersed in aqueous solutions of nonionic detergents. The method provides a unique approach to the study of oil-removal kinetics in nonionic detergent systems where traditional optical techniques fail due to solution turbidity. The only requirement of the NMR experiment is the use of deuterated water in order to selectively image the hydrocarbon phase. Preliminary applications to laundering and paper deinking are discussed.

  7. NMR Spectroscopic Investigations of Catalyzed Reactions. Mechanisms, Kinetics & Unexpected Intermediates

    OpenAIRE

    Leutzsch, Markus

    2015-01-01

    This thesis describes mechanistic studies by NMR spectroscopy in different areas of homogenous catalysis. Over the last years a wide range of organocatalysts were developed enabling highly diverse transformations with high enantioselectivities and excellent yields. In contrast to the high amount of publications on this field, a mechanistic understanding based on experimental evidences is often underinvestigated. Therefore the first two chapters of this thesis are focused on various (NMR-)...

  8. NMR and protein folding: equilibrium and stopped-flow studies.

    OpenAIRE

    Frieden, C.; Hoeltzli, S D; Ropson, I. J.

    1993-01-01

    NMR studies are now unraveling the structure of intermediates of protein folding using hydrogen-deuterium exchange methodologies. These studies provide information about the time dependence of formation of secondary structure. They require the ability to assign specific resonances in the NMR spectra to specific amide protons of a protein followed by experiments involving competition between folding and exchange reactions. Another approach is to use 19F-substituted amino acids to follow change...

  9. Rapid characterization of molecular diffusion by NMR spectroscopy.

    Science.gov (United States)

    Pudakalakatti, Shivanand M; Chandra, Kousik; Thirupathi, Ravula; Atreya, Hanudatta S

    2014-11-24

    An NMR-based approach for rapid characterization of translational diffusion of molecules has been developed. Unlike the conventional method of acquiring a series of 2D (13)C and (1)H spectra, the proposed approach involves a single 2D NMR spectrum, which can be acquired in minutes. Using this method, it was possible to detect the presence of intermediate oligomeric species of diphenylalanine in solution during the process of its self-assembly to form nanotubular structures. PMID:25331210

  10. NMR studies of thermoresponsive polymers in aqueous solutions and hydrogels

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří

    Poznań : Department of Macromolecular Physics, Faculty of Physics and NanoBioMedical Centre, Adam Mickiewicz University in Poznań, The Centre for European Integration, 2014 - (Jurga, S.). s. 27 [Ampere NMR School. 22.06.2014-28.06.2014, Zakopane] R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : NMR * thermoresponsive polymer * aqueous solution Subject RIV: CD - Macromolecular Chemistry

  11. NMR investigations of thermoresponsive polymers in aqueous solutions

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří

    Poznaň : Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 2012. s. 26. [Ampere NMR School. 24.06.2012-30.06.2012, Poznaň] R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : thermoresponsive polymer * aqueous solution * NMR Subject RIV: CD - Macromolecular Chemistry

  12. NMR study in amorphous CoZr thin film alloys

    International Nuclear Information System (INIS)

    59Co NMR study has been carried out in a series of magnetic thin film amorphous Co1-xZrx alloys in the concentration range 0.1< x<0.4. The analysis shows that every Zr nearest neighbour lowers the NMR frequency on Co in the amorphous CoZr alloys by about 30 MHz and that the alloy structure in Co-rich compositions resembles the polytetrahedrally closed packed crystalline phases. (orig.)

  13. Dynamics of Antibody Domains Studied by Solution NMR

    OpenAIRE

    Vu, Bang K.; Walsh, Joseph D.; Dimitrov, Dimiter S.; Ishima, Rieko

    2009-01-01

    Information on local dynamics of antibodies is important to evaluate stability, to rationally design variants, and to clarify conformational disorders at the epitope binding sites. Such information may also be useful for improved understanding of antigen recognition. NMR can be used for characterization of local protein dynamics at the atomic level through relaxation measurements. Due to the complexity of the NMR spectra, an extensive use of this method is limited to small protein molecules, ...

  14. Flow units from integrated WFT and NMR data

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-08-01

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

  15. Solid state NMR coal science. Final progress report

    Energy Technology Data Exchange (ETDEWEB)

    Zilm, K.W.

    1986-08-01

    This report covers the final work on this project and summarizes the accomplishments of the project. The dipolar shift correlated 2D NMR method described in previous reports has been applied to a whole coal successfully. The theory necessary for semi-quantitative interpretation of this data has also been worked out and implemented computationally. Several interesting structural features in coal seen by the 2D dipolar shift experiment not previously observed by other NMR methods are discussed. 4 figs.

  16. Perspectives on a Solid State NMR Quantum Computer

    CERN Document Server

    Feldman, E B; Fel'dman, Edward B.; Lacelle, Serge

    2001-01-01

    A quantum information processing device, based on bulk solid state NMR of the quasi-one dimensional material hydroxyapatite, is proposed following the magnetic resonance force microscopy work of Yamamoto et al (quant-ph/0009122). In a macroscopic sample of hydroxyapatite, our solid state NMR model yields a limit of 10^8 qubits imposed by physics, while development of current technological considerations should allow an upper bound in the range of hundreds to thousands of qubits.

  17. 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.

  18. 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 ostatní: 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

  19. Manifestations of nuclear anapole moments in solid state NMR

    CERN Document Server

    Mukhamedjanov, T N; Cadogan, J M

    2004-01-01

    We suggest to use insulating garnets doped by rare earth ions for measurements of nuclear anapole moments. A parity violating shift of the NMR frequency arises due to the combined effect of the lattice crystal field and the anapole moment of the rare-earth nucleus. We show that there are two different observable effects related to frequency: 1) A shift of the NMR frequency in an external electric field applied to the solid. The value of the shift is about \\Delta \

  20. Study of reference material for NMR core analysis

    International Nuclear Information System (INIS)

    Reference Materials of NMR core experimental analysis have been studied systematically in this paper. According to the national standard criterion, a set of NMR reference materials have been made successfully. These reference materials include fluid pattern-D2O and H2O, divergence of glass grain muster, and the solid ceramics. They have been applied to the core analysis in Daqing, Xinjiang, Dagang Oilfield, etc. The results show, fluid pattern, divergence of glass grain muster as well as ceramics reference materials have different calibration results of core NMR porosity as a result of their different relaxation mechanisms. Fluid pattern is suitable for NMR porosity calibration in Berea sandstone as well as terrestrial sediment sand with little shale content and well sorted. Ceramics reference material is applied to shaly sand with average sorted. Both fluid pattern and solid ceramics material are not suitable for calibration in sandstone sample with high clay content, complex lithology with rich paramagnetic materials. It is suggested that the representative natural core sample should be selected as regional reference material to calibrate NMR porosity of complex lithology, or internal magnetic field gradient in complex rock grain/fluid system should be studied in order to get corrected NMR porosity. (authors)

  1. NMR-based screening of membrane protein ligands.

    Science.gov (United States)

    Yanamala, Naveena; Dutta, Arpana; Beck, Barbara; van Vliet, Bart; van Fleet, Bart; Hay, Kelly; Yazbak, Ahmad; Ishima, Rieko; Doemling, Alexander; Klein-Seetharaman, Judith

    2010-03-01

    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 ligands non-specifically, overlap with protein signals, modulate protein dynamics and conformational exchange and compromise sensitivity by adding highly intense background signals. In this article, we discuss the special considerations arising from these problems when conducting NMR-based ligand-binding studies with membrane proteins. While the use of (13)C and (15)N isotopes is becoming increasingly feasible, (19)F and (1)H NMR-based approaches are currently the most widely explored. By using suitable NMR parameter selection schemes independent of or exploiting the presence of detergent, (1)H-based approaches require least effort in sample preparation because of the high sensitivity and natural abundance of (1)H in both, ligand and protein. On the other hand, the (19)F nucleus provides an ideal NMR probe because of its similarly high sensitivity to that of (1)H and the lack of natural (19)F background in biologic systems. Despite its potential, the use of NMR spectroscopy is highly underdeveloped in the area of drug discovery for membrane proteins. PMID:20331645

  2. Ultrafast 2D NMR: An Emerging Tool in Analytical Spectroscopy

    Science.gov (United States)

    Giraudeau, Patrick; Frydman, Lucio

    2014-06-01

    Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago, a so-called ultrafast (UF) approach was proposed, capable of delivering arbitrary 2D NMR spectra involving any kind of homo- or heteronuclear correlation, in a single scan. During the intervening years, the performance of this subsecond 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool experiencing an expanded scope of applications. This review summarizes the principles and main developments that have contributed to the success of this approach and focuses on applications that have been recently demonstrated in various areas of analytical chemistry—from the real-time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications.

  3. NMR Logging to Estimate Hydraulic Conductivity in Unconsolidated Aquifers.

    Science.gov (United States)

    Knight, Rosemary; Walsh, David O; Butler, James J; Grunewald, Elliot; Liu, Gaisheng; Parsekian, Andrew D; Reboulet, Edward C; Knobbe, Steve; Barrows, Mercer

    2016-01-01

    Nuclear magnetic resonance (NMR) logging provides a new means of estimating the hydraulic conductivity (K) of unconsolidated aquifers. The estimation of K from the measured NMR parameters can be performed using the Schlumberger-Doll Research (SDR) equation, which is based on the Kozeny-Carman equation and initially developed for obtaining permeability from NMR logging in petroleum reservoirs. The SDR equation includes empirically determined constants. Decades of research for petroleum applications have resulted in standard values for these constants that can provide accurate estimates of permeability in consolidated formations. The question we asked: Can standard values for the constants be defined for hydrogeologic applications that would yield accurate estimates of K in unconsolidated aquifers? Working at 10 locations at three field sites in Kansas and Washington, USA, we acquired NMR and K data using direct-push methods over a 10- to 20-m depth interval in the shallow subsurface. Analysis of pairs of NMR and K data revealed that we could dramatically improve K estimates by replacing the standard petroleum constants with new constants, optimal for estimating K in the unconsolidated materials at the field sites. Most significant was the finding that there was little change in the SDR constants between sites. This suggests that we can define a new set of constants that can be used to obtain high resolution, cost-effective estimates of K from NMR logging in unconsolidated aquifers. This significant result has the potential to change dramatically the approach to determining K for hydrogeologic applications. PMID:25810149

  4. The theoretic design of NMR pulses program of arbitrary N-qubit Grover's algorithm and the NMR experiment proof

    Institute of Scientific and Technical Information of China (English)

    YANG; Xiaodong(杨晓冬); MIAO; Xijia(缪希茄)

    2002-01-01

    Grover's quantum searching algorithm is most widely studied in the current quantum computation research, and has been implemented experimentally by NMR (Nuclear Magnetic Resonance) technique. In this article, we design arbitrary N-qubit NMR pulses program of Grover's algorithm based on the multiple-quantum operator algebra theory and demonstrate 2-qubit pulses program experimentally. The result also proves the validity of the multiple-quantum operator algebra theory.

  5. (13)C NMR assignments of regenerated cellulose from solid-state 2D NMR spectroscopy.

    Science.gov (United States)

    Idström, Alexander; Schantz, Staffan; Sundberg, Johan; Chmelka, Bradley F; Gatenholm, Paul; Nordstierna, Lars

    2016-10-20

    From the assignment of the solid-state (13)C NMR signals in the C4 region, distinct types of crystalline cellulose, cellulose at crystalline surfaces, and disordered cellulose can be identified and quantified. For regenerated cellulose, complete (13)C assignments of the other carbon regions have not previously been attainable, due to signal overlap. In this study, two-dimensional (2D) NMR correlation methods were used to resolve and assign (13)C signals for all carbon atoms in regenerated cellulose. (13)C-enriched bacterial nanocellulose was biosynthesized, dissolved, and coagulated as highly crystalline cellulose II. Specifically, four distinct (13)C signals were observed corresponding to conformationally different anhydroglucose units: two signals assigned to crystalline moieties and two signals assigned to non-crystalline species. The C1, C4 and C6 regions for cellulose II were fully examined by global spectral deconvolution, which yielded qualitative trends of the relative populations of the different cellulose moieties, as a function of wetting and drying treatments. PMID:27474592

  6. Accessible surface area from NMR chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hafsa, Noor E.; Arndt, David; Wishart, David S., E-mail: david.wishart@ualberta.ca [University of Alberta, Department of Computing Science (Canada)

    2015-07-15

    Accessible surface area (ASA) is the surface area of an atom, amino acid or biomolecule that is exposed to solvent. The calculation of a molecule’s ASA requires three-dimensional coordinate data and the use of a “rolling ball” algorithm to both define and calculate the ASA. For polymers such as proteins, the ASA for individual amino acids is closely related to the hydrophobicity of the amino acid as well as its local secondary and tertiary structure. For proteins, ASA is a structural descriptor that can often be as informative as secondary structure. Consequently there has been considerable effort over the past two decades to try to predict ASA from protein sequence data and to use ASA information (derived from chemical modification studies) as a structure constraint. Recently it has become evident that protein chemical shifts are also sensitive to ASA. Given the potential utility of ASA estimates as structural constraints for NMR we decided to explore this relationship further. Using machine learning techniques (specifically a boosted tree regression model) we developed an algorithm called “ShiftASA” that combines chemical-shift and sequence derived features to accurately estimate per-residue fractional ASA values of water-soluble proteins. This method showed a correlation coefficient between predicted and experimental values of 0.79 when evaluated on a set of 65 independent test proteins, which was an 8.2 % improvement over the next best performing (sequence-only) method. On a separate test set of 92 proteins, ShiftASA reported a mean correlation coefficient of 0.82, which was 12.3 % better than the next best performing method. ShiftASA is available as a web server ( http://shiftasa.wishartlab.com http://shiftasa.wishartlab.com ) for submitting input queries for fractional ASA calculation.

  7. Accessible surface area from NMR chemical shifts

    International Nuclear Information System (INIS)

    Accessible surface area (ASA) is the surface area of an atom, amino acid or biomolecule that is exposed to solvent. The calculation of a molecule’s ASA requires three-dimensional coordinate data and the use of a “rolling ball” algorithm to both define and calculate the ASA. For polymers such as proteins, the ASA for individual amino acids is closely related to the hydrophobicity of the amino acid as well as its local secondary and tertiary structure. For proteins, ASA is a structural descriptor that can often be as informative as secondary structure. Consequently there has been considerable effort over the past two decades to try to predict ASA from protein sequence data and to use ASA information (derived from chemical modification studies) as a structure constraint. Recently it has become evident that protein chemical shifts are also sensitive to ASA. Given the potential utility of ASA estimates as structural constraints for NMR we decided to explore this relationship further. Using machine learning techniques (specifically a boosted tree regression model) we developed an algorithm called “ShiftASA” that combines chemical-shift and sequence derived features to accurately estimate per-residue fractional ASA values of water-soluble proteins. This method showed a correlation coefficient between predicted and experimental values of 0.79 when evaluated on a set of 65 independent test proteins, which was an 8.2 % improvement over the next best performing (sequence-only) method. On a separate test set of 92 proteins, ShiftASA reported a mean correlation coefficient of 0.82, which was 12.3 % better than the next best performing method. ShiftASA is available as a web server ( http://shiftasa.wishartlab.com http://shiftasa.wishartlab.com ) for submitting input queries for fractional ASA calculation

  8. Monitoring prion protein stability by NMR.

    Science.gov (United States)

    Julien, Olivier; Graether, Steffen P; Sykes, Brian D

    2009-01-01

    Prion diseases, or transmissible spongiform encephalopathies (TSE), are a group of fatal neurological diseases that affect both humans and animals. At the end of the 20th century, bovine spongiform encephalopathy (BSE), better known as mad cow disease, was shown to be transmissible to humans. This resulted in considerable concern for public health and a number of questions for scientists. The first question answered was the possible source of the disease, which appears to be the prion protein (PrP). There are two major forms of this protein: the native, noninfectious form (PrP(C)), and the misfolded infectious form (PrP(Sc)). PrP(C) is mainly alpha-helical in structure, whereas PrP(Sc) aggregates into an assembly of beta-sheets, forming amyloid fibrils. Since the first solution structure of the noninfectious form of the mouse prion protein, about 30 structures of the globular portion of PrP(C) have been characterized from different organisms. However, only a few minor differences are observed when comparing one PrP(C) structure to another. The key to understanding prion formation may then be not in the structure of PrP(C), but in the mechanism underlying PrP(C) unfolding and then conversion into a misfolded fibril state. To identify the possible region(s) of PrP(C) responsible for initiating the conversion into the amyloid fibril formation, nuclear magnetic resonance (NMR) was applied to characterize the stability and structure of PrP(C) and intermediate states during the conversion from PrP(C) to PrP(Sc). Subsequently urea was used to induce unfolding, and data analysis revealed region-specific structural stabilities that may bring insights into the mechanisms underlying conversion of protein into an infectious prion. PMID:19697241

  9. GEL-STATE NMR OF BALL-MILLED WHOLE CELL WALLS IN DMSO-d6 USING 2D SOLUTION-STATE NMR SPECTROSCOPY

    Science.gov (United States)

    Plant cell walls were used for obtaining 2D solution-state NMR spectra without actual solubilization or structural modification. Ball-milled whole cell walls were swelled directly in the NMR tube with DMSO-d6 where they formed a gel. There are relatively few gel-state NMR studies. Most have involved...

  10. 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

  11. Transient protein-protein interactions visualized by solution NMR.

    Science.gov (United States)

    Liu, Zhu; Gong, Zhou; Dong, Xu; Tang, Chun

    2016-01-01

    Proteins interact with each other to establish their identities in cell. The affinities for the interactions span more than ten orders of magnitude, and KD values in μM-mM regimen are considered transient and are important in cell signaling. Solution NMR including diamagnetic and paramagnetic techniques has enabled atomic-resolution depictions of transient protein-protein interactions. Diamagnetic NMR allows characterization of protein complexes with KD values up to several mM, whereas ultraweak and fleeting complexes can be modeled with the use of paramagnetic NMR especially paramagnetic relaxation enhancement (PRE). When tackling ever-larger protein complexes, PRE can be particularly useful in providing long-range intermolecular distance restraints. As NMR measurements are averaged over the ensemble of complex structures, structural information for dynamic protein-protein interactions besides the stereospecific one can often be extracted. Herein the protein interaction dynamics are exemplified by encounter complexes, alternative binding modes, and coupled binding/folding of intrinsically disordered proteins. Further integration of NMR with other biophysical techniques should allow better visualization of transient protein-protein interactions. In particular, single-molecule data may facilitate the interpretation of ensemble-averaged NMR data. Though same structures of proteins and protein complexes were found in cell as in diluted solution, we anticipate that the dynamics of transient protein protein-protein interactions be different, which awaits awaits exploration by NMR. This article is part of a Special Issue entitled: Physiological Enzymology and Protein Functions. This article is part of a Special Issue entitled: Physiological Enzymology and Protein Functions. PMID:25896389

  12. NMR imaging and cryoporometry of swelling clays

    Science.gov (United States)

    Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

    2010-05-01

    strength as well as investigating the effect of the confining geometry and material surface properties seem to be worth to pursue. Acknowledgements: This work has been supported by the Swedish Nuclear Fuel and Waste Management Co (SKB) and the Swedish Research Council VR. References: [1] Dvinskikh S. V., Szutkowski K., Furó I. MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay. J. Magn. Reson. 198, 146 (2009). [2] Petrov O. V., Furó I. NMR cryoporometry: Principles, applications and potential. Prog. Nucl. Magn. Reson. Spec. 54, 97 (2009).

  13. Low Cost CE-NMR with Microcoils for Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    Adams, K L; Klunder, G; Demas, V; Malba, V; Bernhardt, A; Evan, L; Harvey, C; Maxwell, R; Herberg, J

    2008-07-25

    Understanding speciation in solids and solutions is important for environmental and toxicological purposes. Capillary electrophoresis (CE) is a simple rapid separation technique that can be used to identify species in solution. CE is particularly is well suited for rapid separations of metal containing samples. Direct on-capillary measurement of metal compound speciation can be obtained with nuclear magnetic resonance (NMR). The development of a low-cost microcoil CE-NMR system for in situ characterization of samples of interest is discussed. High precision laser lithography is used to produce copper sputtered microcoils that have comparable resistivity and quality factors to that of hand wound microcoils. A portable NMR system coupled with a CE system has the potential to identify chemical species in aqueous solutions. In addition, transient isotachophoresis can separate and pre-concentrate samples of interest to obtain separate chemical peaks for speciation by online NMR analysis. We are developing separation assays to determine the speciation of chemical complexes in solutions with minimal perturbation to the original sample equilibrium. On-line NMR measurements will be made downstream of the UV detector.

  14. Low Cost CE-NMR with Microcoils for Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    Adams, K; Klunder, G; Demas, V; Malba, V; Bernhardt, A; Evan, L; Harvey, C; Maxwell, R; Herberg, J L

    2009-01-08

    Understanding speciation in solids and solutions is important for environmental and toxicological purposes. Capillary electrophoresis (CE) is a simple rapid separation technique that can be used to identify species in solution. CE is particularly is well suited for rapid separations of metal containing samples. Direct on-capillary measurement of metal compound speciation can be obtained with nuclear magnetic resonance (NMR). The development of a low-cost microcoil CE-NMR system for in situ characterization of samples of interest is discussed. High precision laser lithography is used to produce copper sputtered microcoils that have comparable resistivity and quality factors to that of hand wound microcoils. A portable NMR system coupled with a CE system has the potential to identify chemical species in aqueous solutions. In addition, transient isotachophoresis can separate and pre-concentrate samples of interest to obtain separate chemical peaks for speciation by online NMR analysis. We are developing separation assays to determine the speciation of chemical complexes in solutions with minimal perturbation to the original sample equilibrium. On-line NMR measurements will be made downstream of the UV detector.

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

    International Nuclear Information System (INIS)

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

  16. GFT projection NMR spectroscopy for proteins in the solid state

    International Nuclear Information System (INIS)

    Recording of four-dimensional (4D) spectra for proteins in the solid state has opened new avenues to obtain virtually complete resonance assignments and three-dimensional (3D) structures of proteins. As in solution state NMR, the sampling of three indirect dimensions leads per se to long minimal measurement time. Furthermore, artifact suppression in solid state NMR relies primarily on radio-frequency pulse phase cycling. For an n-step phase cycle, the minimal measurement times of both 3D and 4D spectra are increased n times. To tackle the associated 'sampling problem' and to avoid sampling limited data acquisition, solid state G-Matrix Fourier Transform (SS GFT) projection NMR is introduced to rapidly acquire 3D and 4D spectral information. Specifically, (4,3)D (HA)CANCOCX and (3,2)D (HACA)NCOCX were implemented and recorded for the 6 kDa protein GB1 within about 10% of the time required for acquiring the conventional congeners with the same maximal evolution times and spectral widths in the indirect dimensions. Spectral analysis was complemented by comparative analysis of expected spectral congestion in conventional and GFT NMR experiments, demonstrating that high spectral resolution of the GFT NMR experiments enables one to efficiently obtain nearly complete resonance assignments even for large proteins.

  17. Quantum Mechanical Nature in Liquid NMR Quantum Computing

    Institute of Scientific and Technical Information of China (English)

    LONG Gui-Lu; YAN Hai-Yang; LI Yan-Song; TU Chang-Cun; ZHU Sheng-Jiang; RUAN Dong; SUN Yang; TAO Jia-Xun; CHEN Hao-Ming

    2002-01-01

    The quantum nature of bulk ensemble NMR quantum computing the center of recent heated debate,is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMRquantum computation are analyzed. The main points in this paper are: i) Density matrix describes the "state" of anaverage particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglementis a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separabilityof the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMRquantum computation is quantum-mechanical; iv) The coefficient before the effective pure state densitymatrix, e, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signaland has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of thedensity matrix into product states is only an indication that the ensemble can be prepared by an ensemble with theparticles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classicalsimulations.

  18. High resolution deuterium NMR studies of bacterial metabolism

    International Nuclear Information System (INIS)

    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

  19. High resolution deuterium NMR studies of bacterial metabolism

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-12-25

    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.

  20. Batch profiling calibration for robust NMR metabonomic data analysis.

    Science.gov (United States)

    Fages, Anne; Pontoizeau, Clément; Jobard, Elodie; Lévy, Pierre; Bartosch, Birke; Elena-Herrmann, Bénédicte

    2013-11-01

    Metabonomic studies involve the analysis of large numbers of samples to identify significant changes in the metabolic fingerprints of biological systems, possibly with sufficient statistical power for analysis. While procedures related to sample preparation and spectral data acquisition generally include the use of independent sample batches, these might be sources of systematic variation whose effects should be removed to focus on phenotyping the relevant biological variability. In this work, we describe a grouped-batch profile (GBP) calibration strategy to adjust nuclear magnetic resonance (NMR) metabolomic data-sets for batch effects either introduced during NMR experiments or samples work-up. We show how this method can be applied to data calibration in the context of a large-scale NMR epidemiological study where quality control samples are available. We also illustrate the efficiency of a batch profile correction for NMR metabonomic investigation of cell extracts, where GBP can significantly improve the predictive power of multivariate statistical models for discriminant analysis of the cell infection status. The method is applicable to a broad range of NMR metabolomic/metabonomic cohort studies. PMID:23975089

  1. 29Si NMR: A new tool for coal liquids characterization

    Science.gov (United States)

    Rose, K. D.; Scouten, C. G.

    1981-02-01

    Protonated heteroatom functionalities (COOH, OH, Sh, NH) have a major impact on the chemical and physical properties of coal materials. Characterization of these functionalities will, therefore, be important to efficient development of new coal utilization technologies. Silicon-29 NMR spectroscopy of the trimethysilyl derivatives of these functional groups is a powerful new tool for this characterization. Preparation of the trimethylsilyl derivatives is carried out in the NMR sample tube and the 29Si NMR spectrum of the products is accumulated under conditions similar to those routinely used in 13NMR. Studies on derivatized model compounds show that 29Si chemical shifts are generally segraged into three regions characteristic of COOh, OH and SH, and NH functionalities. The 29Si resonances of aromatic OH derivatives are further differentiated so that the major oxygenated components of coal liquids can be monitored as a function of processing and distillation conditions. Quantitative 29Si NMR results are used to calculate total OH and COOH concentrations in several solutions. Comparison of these results with the elemental oxygen content permits an estimated of the percentage oxygen present in non-derivatizable (e.g., ether) groups. The technique is illustrated using soluble coal liquid distillate fractions boiling in the range of initial boiling point to 1050°F (566 °C).

  2. Development of a superconducting bulk magnet for NMR and MRI

    Science.gov (United States)

    Nakamura, Takashi; Tamada, Daiki; Yanagi, Yousuke; Itoh, Yoshitaka; Nemoto, Takahiro; Utumi, Hiroaki; Kose, Katsumi

    2015-10-01

    A superconducting bulk magnet composed of six vertically stacked annular single-domain c-axis-oriented Eu-Ba-Cu-O crystals was energized to 4.74 T using a conventional superconducting magnet for high-resolution NMR spectroscopy. Shim coils, gradient coils, and radio frequency coils for high resolution NMR and MRI were installed in the 23 mm-diameter room-temperature bore of the bulk magnet. A 6.9 ppm peak-to-peak homogeneous region suitable for MRI was achieved in the central cylindrical region (6.2 mm diameter, 9.1 mm length) of the bulk magnet by using a single layer shim coil. A 21 Hz spectral resolution that can be used for high resolution NMR spectroscopy was obtained in the central cylindrical region (1.3 mm diameter, 4 mm length) of the bulk magnet by using a multichannel shim coil. A clear 3D MR image dataset of a chemically fixed mouse fetus with (50 μm)3 voxel resolution was obtained in 5.5 h. We therefore concluded that the cryogen-free superconducting bulk magnet developed in this study is useful for high-resolution desktop NMR, MRI and mobile NMR device.

  3. Application of Solution NMR Spectroscopy to Study Protein Dynamics

    Directory of Open Access Journals (Sweden)

    Christoph Göbl

    2012-03-01

    Full Text Available Recent advances in spectroscopic methods allow the identification of minute fluctuations in a protein structure. These dynamic properties have been identified as keys to some biological processes. The consequences of this structural flexibility can be far‑reaching and they add a new dimension to the structure-function relationship of biomolecules. Nuclear Magnetic Resonance (NMR spectroscopy allows the study of structure as well as dynamics of biomolecules in a very broad range of timescales at atomic level. A number of new NMR methods have been developed recently to allow the measurements of time scales and spatial fluctuations, which in turn provide the thermodynamics associated with the biological processes. Since NMR parameters reflect ensemble measurements, structural ensemble approaches in analyzing NMR data have also been developed. These new methods in some instances can even highlight previously hidden conformational features of the biomolecules. In this review we describe several solution NMR methods to study protein dynamics and discuss their impact on important biological processes.

  4. A survey on quantitative analysis of organic compounds by nuclear magnetic resonance (NMR) spectroscopy

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) spectroscopy is known as a powerful analytical technique, which is used to determine the structure of small and macro organic compounds. In recent years, 1H NMR is being recognized more and more as a quantitative analytical method, which is based on the principle where the area under a 1H NMR signal peak in solution state is proportional to the number of nuclei contributing to the peak. In this report, the basic concepts, developmental history and current state of the quantitative 1H NMR (qNMR) method are described. Furthermore, future prospect of the qNMR method is presented. (author)

  5. Detection of thin film NMR spectrum by Magnetic Resonance Force Microscopy

    Science.gov (United States)

    Saun, Seung-Bo; Kwon, Sungmin; Lee, Soonchil; Won, Soonho

    2014-03-01

    NMR is widely used in many fields due to its powerful advantages such as nondestructive, chemically selective detection, and local probing. However, because of its low sensitivity, it is difficult to investigate thin film samples by conventional NMR. MRFM is the combined technic of NMR and Scanning Probe Microscopy (SPM), and it enabled exceptional sensitivity increasement of NMR detection. We succeeded in detecting general thin film NMR spectrum for the first time by modifying the MRFM. CaF2 34nm thin film NMR was detected and we observed 20 Gauss spectrum in proximity to bulk spectrum which is about 10 Gauss.

  6. 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.

  7. Deuterium NMR Studies of the Structure and Dynamics of Gramicidin.

    Science.gov (United States)

    Hing, Andrew William

    1990-01-01

    The structure and dynamics of the membrane peptide gramicidin are investigated by deuterium NMR. A specific structural and dynamical question about the peptide backbone of gramicidin is investigated by deuterating the alpha carbon of the third alanine residue. Deuterium NMR experiments performed on this analog in oriented lipid bilayers indicate that the c_alpha- ^2H bond makes an angle relative to the helical axis that is in agreement with the bond angle predicted by the beta^{6.3} helical model. A second structural and dynamical question about the peptide backbone of gramicidin is investigated by deuterating the formyl group of two different analogs. Deuterium NMR experiments performed on these analogs show that the spectra of the two analogs are very similar. However, the analog possessing D-leucine as the second residue also appears to exist in a second, minor conformation which does not seem to exist for the analog possessing glycine as the second residue.

  8. Computer systems for laboratory networks and high-performance NMR.

    Science.gov (United States)

    Levy, G C; Begemann, J H

    1985-08-01

    Modern computer technology is significantly enhancing the associated tasks of spectroscopic data acquisition and data reduction and analysis. Distributed data processing techniques, particularly laboratory computer networking, are rapidly changing the scientist's ability to optimize results from complex experiments. Optimization of nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI) experimental results requires use of powerful, large-memory (virtual memory preferred) computers with integrated (and supported) high-speed links to magnetic resonance instrumentation. Laboratory architectures with larger computers, in order to extend data reduction capabilities, have facilitated the transition to NMR laboratory computer networking. Examples of a polymer microstructure analysis and in vivo 31P metabolic analysis are given. This paper also discusses laboratory data processing trends anticipated over the next 5-10 years. Full networking of NMR laboratories is just now becoming a reality. PMID:3840171

  9. NMR structure improvement: A structural bioinformatics & visualization approach

    Science.gov (United States)

    Block, Jeremy N.

    The overall goal of this project is to enhance the physical accuracy of individual models in macromolecular NMR (Nuclear Magnetic Resonance) structures and the realism of variation within NMR ensembles of models, while improving agreement with the experimental data. A secondary overall goal is to combine synergistically the best aspects of NMR and crystallographic methodologies to better illuminate the underlying joint molecular reality. This is accomplished by using the powerful method of all-atom contact analysis (describing detailed sterics between atoms, including hydrogens); new graphical representations and interactive tools in 3D and virtual reality; and structural bioinformatics approaches to the expanded and enhanced data now available. The resulting better descriptions of macromolecular structure and its dynamic variation enhances the effectiveness of the many biomedical applications that depend on detailed molecular structure, such as mutational analysis, homology modeling, molecular simulations, protein design, and drug design.

  10. Multidimensional NMR Inversion without Kronecker Products: Multilinear Inversion

    CERN Document Server

    Medellín, David; Torres-Verdín, Carlos

    2016-01-01

    Multidimensional NMR inversion using Kronecker products poses several challenges. First, kernel compression is only possible when the kernel matrices are separable, and in recent years, there has been an increasing interest in NMR sequences with non-separable kernels. Second, in three or more dimensions, the singular value decomposition is not unique; therefore kernel compression is not well-defined for higher dimensions. Without kernel compression, the Kronecker product yields matrices that require large amounts of memory, making the inversion intractable for personal computers. Finally, incorporating arbitrary regularization terms is not possible using the Lawson-Hanson (LH) or the Butler-Reeds-Dawson (BRD) algorithms. We develop a minimization-based inversion method that circumvents the above problems by using multilinear forms to perform multidimensional NMR inversion without using kernel compression or Kronecker products. The new method is memory efficient, requiring less than 0.1% of the memory required...

  11. NMR/MRI with hyperpolarized gas and high Tc SQUID

    Science.gov (United States)

    Schlenga, Klaus; de Souza, Ricardo E.; Wong-Foy, Annjoe; Clarke, John; Pines, Alexander

    2000-01-01

    A method and apparatus for the detection of nuclear magnetic resonance (NMR) signals and production of magnetic resonance imaging (MRI) from samples combines the use of hyperpolarized inert gases to enhance the NMR signals from target nuclei in a sample and a high critical temperature (Tc) superconducting quantum interference device (SQUID) to detect the NMR signals. The system operates in static magnetic fields of 3 mT or less (down to 0.1 mT), and at temperatures from liquid nitrogen (77K) to room temperature. Sample size is limited only by the size of the magnetic field coils and not by the detector. The detector is a high Tc SQUID magnetometer designed so that the SQUID detector can be very close to the sample, which can be at room temperature.

  12. Solid-state NMR on defects in lead titanates

    International Nuclear Information System (INIS)

    Failure of ferroelectrics is not well understood. In our approach, we employ various solid-state NMR techniques to characterize and quantify chemical structures that arise from crystallographic defects. Especially, the existence and distributions of 1H as water or other species is a primary goal in our research. 1H spectra are known to be often of low resolution due to the strong homonuclear dipolar coupling. With sophisticated NMR techniques, e. g. echo methods and multiple quantum transitions, we want to get more insight into the defect structures. This enables both improvement in spectral resolution as well as to obtain information about the dynamics of present chemical structures such as water. Additionally, all nuclei present in lead titanates are accessible by NMR with different degree of sensitivity. Especially, with self-built equipment we are able to increase the abundance of the 17O nuclei and therefore allow for detection

  13. 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.

  14. Mobile sensor for high resolution NMR spectroscopy and imaging

    Science.gov (United States)

    Danieli, Ernesto; Mauler, Jörg; Perlo, Juan; Blümich, Bernhard; Casanova, Federico

    2009-05-01

    In this work we describe the construction of a mobile NMR tomograph with a highly homogeneous magnetic field. Fast MRI techniques as well as NMR spectroscopy measurements were carried out. The magnet is based on a Halbach array built from identical permanent magnet blocks generating a magnetic field of 0.22 T. To shim the field inhomogeneities inherent to magnet arrays constructed from these materials, a shim strategy based on the use of movable magnet blocks is employed. With this approach a reduction of the line-width from ˜20 kHz to less than 0.1 kHz was achieved, that is by more than two orders of magnitude, in a volume of 21 cm 3. Implementing a RARE sequence, 3D images of different objects placed in this volume were obtained in short experimental times. Moreover, by reducing the sample size to 1 cm 3, sub ppm resolution is obtained in 1H NMR spectra.

  15. 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)

  16. 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. PMID:27457481

  17. High resolution NMR measurements using a 400 MHz NMR with an (RE)Ba2Cu3O7-x high-temperature superconducting inner coil: Towards a compact super-high-field NMR

    Science.gov (United States)

    Piao, R.; Iguchi, S.; Hamada, M.; Matsumoto, S.; Suematsu, H.; Saito, A. T.; Li, J.; Nakagome, H.; Takao, T.; Takahashi, M.; Maeda, H.; Yanagisawa, Y.

    2016-02-01

    Use of high-temperature superconducting (HTS) inner coils in combination with conventional low-temperature superconducting (LTS) outer coils for an NMR magnet, i.e. a LTS/HTS NMR magnet, is a suitable option to realize a high-resolution NMR spectrometer with operating frequency >1 GHz. From the standpoint of creating a compact magnet, (RE: Rare earth) Ba2Cu3O7-x (REBCO) HTS inner coils which can tolerate a strong hoop stress caused by a Lorentz force are preferred. However, in our previous work on a first-generation 400 MHz LTS/REBCO NMR magnet, the NMR resolution and sensitivity were about ten times worse than that of a conventional LTS NMR magnet. The result was caused by a large field inhomogeneity in the REBCO coil itself and the shielding effect of a screening current induced in that coil. In the present paper, we describe the operation of a modified 400 MHz LTS/REBCO NMR magnet with an advanced field compensation technology using a combination of novel ferromagnetic shimming and an appropriate procedure for NMR spectrum line shape optimization. We succeeded in obtaining a good NMR line shape and 2D NOESY spectrum for a lysozyme aqueous sample. We believe that this technology is indispensable for the realization of a compact super-high-field high-resolution NMR.

  18. NMR imaging of fluid dynamics in reservoir core.

    Science.gov (United States)

    Baldwin, B A; Yamanashi, W S

    1988-01-01

    A medical NMR imaging instrument has been modified to image water and oil in reservoir rocks by the construction of a new receiving coil. Both oil and water inside the core produced readily detectable proton NMR signals, while the rock matrix produced no signal. Because of similar T2 NMR relaxation times, the water was doped with a paramagnetic ion, Mn+2, to reduce its T2 relaxation time. This procedure enhanced the separation between the oil and water phases in the resulting images. Sequential measurements, as water imbibed into one end and oil was expelled from the other end of a core plug, produced a series of images which showed the dynamics of the fluids. For water-wet Berea Sandstone a flood front was readily observed, but some of the oil was apparently left behind in small, isolated pockets which were larger than individual pores. After several additional pore volumes of water flowed through the plug the NMR image indicated a homogeneous distribution of oil. The amount of residual oil, as determined from the ratio of NMR intensities, closely approximated the residual oil saturation of fully flooded Berea samples measured by Dean-Stark extraction. A Berea sandstone core treated to make it partially oil-wet, did not show a definitive flood front, but appeared to channel the water around the perimeter of the core plug. The relative ease with which these images were made indicates that NMR imaging can be a useful technique to follow the dynamics of oil and water through a core plug for a variety of production processes. PMID:3226235

  19. 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.

  20. 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

  1. 31P Solid-state MAS NMR spectra

    International Nuclear Information System (INIS)

    The structures of the silicoaluminiophosphates MCM-1 and MCM9 were characterized by 27Al and 31P MAS NMR. The structural identity of MCM-1 and its silicon-free homologue AlPO4-H3 is demonstrated. The presence of a structural mixture in MCM-9 is confirmed. 31P MAS NMR spectra of MCM-9 could be interpreted as a superposition of spectra of VPI-5, AlPO4-H3 and SAPO-11 phases. (author). 12 refs.; 3 figs.; 1 tab

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

    International Nuclear Information System (INIS)

    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

  3. NMR Probe of Metallic States in Nanoscale Topological Insulators

    OpenAIRE

    Koumoulis, Dimitrios; Chasapis, Thomas C.; Taylor, Robert E; Lake, Michael P.; King, Danny; Jarenwattananon, Nanette N.; Fiete, Gregory A.; Kanatzidis, Mercouri G.; Bouchard, Louis-S.

    2013-01-01

    A 125Te NMR study of bismuth telluride nanoparticles as function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from single to bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from p-band carriers. Whereas nanocrystals follow a Korringa law in the range 140-420K, micrometer particles do so only below 200K. The results reveal increased meta...

  4. An NMR investigation of isotope exchange involving multiply labelled intermediates

    International Nuclear Information System (INIS)

    Information about enzyme systems can be obtained from studies of isotope exchange reactions. NMR can monitor these reactions continuously, even in intact biological samples. In this paper 1H NMR is used to study a 1H/2H exchange process which involves multiple labelling of NADH. The NADH is an intermediate in an exchange process involving the glycolytic enzymes glyceraldehyde phosphate dehydrogenase, lactate dehydrogenase, triose phosphate isomerase and aldolase. The form of the observed exchange is predicted by an extended theory of isotope exchange. (author)

  5. NMR studies of the mechanism of enzyme action

    International Nuclear Information System (INIS)

    No single technique can fully elucidate an enzyme mechanism. The authors' laboratory has therefore been using a number of methods, including NMR, to study two broad classes of enzyme-catalyzed reactions that are ubiquitous in biochemistry, namely, nucleophilic substitutions on phosphorus and the polarization of carbonyl groups. In this chapter the authors first discuss those parameters of NMR spectroscopy that are most useful in studying enzyme mechanisms. They then consider, with specific examples, the mechanisms of enzyme-catalyzed nucleophilic substitution on phosphorus, and enzyme-catalyzed carbonyl polarization reactions, including reactions of biotin

  6. Handbook of proton-NMR spectra and data index

    CERN Document Server

    Asahi Research Center Co, Ltd

    2013-01-01

    Handbook of Proton-NMR Spectra and Data: Index to Volumes 1-10 compiles four types of indexes used in charting the proton-NMR spectral database -Chemical Name Index, Molecular Formula Index, Substructure Index, and Chemical Shift Index. The Chemical Name Index compiles all chemical names in alphabetical order, followed by a spectrum number. When the desired organic compound cannot be found in the Chemical Name Index or its nomenclature is unclear, it becomes necessary to look for a compound by means of its molecular formula, hence the Molecular Formula Index. A unique notation system for repre

  7. Nuclear magnetic resonance (NMR) imaging in Huntington's disease

    International Nuclear Information System (INIS)

    Three patients with Huntington's disease (including two siblings) were evaluated with NMR imaging. Caudate atrophy was seen by inversion recovery (IR) 1000/300 scans in Case I, by IR 1000/300 scans in Case 2, and by IR 1000/300, IR 1000/350, spin-echo (SE) 1080/80, and SE 500/40 scans in Case 3. NMR imaging is considered to be of value in the diagnosis of central nervous diseases by combining several imaging techniques and pulse sequences. (Namekawa, K.)

  8. Applications of NMR in the characterization of pharmaceutical microemulsions.

    Science.gov (United States)

    Hathout, Rania M; Woodman, Timothy J

    2012-07-10

    Microemulsions have successfully proven themselves as useful vehicles for drugs through the different routes of administration because they can confer on drugs greater water solubility and bioavailability. The ability to understand the structural aspects of these important drug delivery systems is essential to the progress of this science. The use of NMR techniques in pharmaceutical and drug delivery science is increasing especially in the characterization field. This review demonstrates the major and novel NMR methods and techniques used in understanding and characterizing the different microemulsion components, types and structures. PMID:22579644

  9. ISOLATION AND NMR SPECTRAL ASSIGNMENTS OF STEVIOLBIOSIDE AND STEVIOSIDE

    Directory of Open Access Journals (Sweden)

    Venkata Sai Prakash Chaturvedula

    2011-04-01

    Full Text Available The complete 1H and 13C NMR assignments of the two diterpene glycosides, 13-[(2-O--D-glucopyranosyl--D-glucopyranosyloxy]-ent-kaur-16-en-19-oic acid (steviolbioside and 3-[(2-O--D-glucopyranosyl--D-glucopyranosyloxy]-ent-kaur-16-en-19-oic acid β-D-glucopyranosyl ester (stevioside isolated from Stevia rebaudiana were achieved on the basis of extensive NMR (1H and 13C, COSY, HMQC, HMBC and MS spectral data. The structures of steviolbioside and stevioside were further supported by acid and enzymatic hydrolysis studies by identifying their corresponding aglycone and sugar residues.

  10. NMR spectroscopic study of the Murex trunculus dyeing process.

    Science.gov (United States)

    Hoffman, Rina C; Zilber, Reut C; Hoffman, Roy E

    2010-11-01

    It is widely accepted that indigo dyes derived from Murex trunculus were used to produce the biblical dyes tekhelet and argaman. We describe a method of following the debromination of natural leucoindigos and their binding to wool using NMR spectroscopy. Debromination is observed prior to reaction with the wool and prior to oxidation. Binding to the wool is shown to occur prior to oxidation. NMR allows the dyeing process to be followed. This, in principle, could be used to correct problems during dyeing that would increase the reliability of the process. PMID:20882520

  11. In situ NMR analysis of fluids contained in sedimentary rock

    Science.gov (United States)

    de Swiet TM; Tomaselli; Hurlimann; Pines

    1998-08-01

    Limitations of resolution and absorption in standard chemical spectroscopic techniques have made it difficult to study fluids in sedimentary rocks. In this paper, we show that a chemical characterization of pore fluids may be obtained in situ by magic angle spinning (MAS) nuclear magnetic resonance (NMR), which is normally used for solid samples. 1H MAS-NMR spectra of water and crude oil in Berea sandstone show sufficient chemical shift resolution for a straightforward determination of the oil/water ratio. Copyright 1998 Academic Press. PMID:9716484

  12. Experimental demonstration of quantum contextuality on an NMR qutrit

    Science.gov (United States)

    Dogra, Shruti; Dorai, Kavita; Arvind

    2016-05-01

    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.

  13. Mapping protein conformational energy landscapes using NMR and molecular simulation

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy provides detailed understanding of the nature and extent of protein dynamics on physiologically important timescales. We present recent advances in the combination of NMR with state-of-the art molecular simulation that are providing unique new insight into the motions on timescales from nanoseconds to milliseconds. In particular, we focus on methods based on residual dipolar couplings (RDCs) that allow for detailed mapping of the protein conformational energy landscape. A novel combination of RDCs with accelerated molecular dynamics allows for the development of ensemble representations of the underlying Boltzmann ensemble. (authors)

  14. NMR Meets Tau: Insights into Its Function and Pathology.

    Science.gov (United States)

    Lippens, Guy; Landrieu, Isabelle; Smet, Caroline; Huvent, Isabelle; Gandhi, Neha S; Gigant, Benoît; Despres, Clément; Qi, Haoling; Lopez, Juan

    2016-01-01

    In this review, we focus on what we have learned from Nuclear Magnetic Resonance (NMR) studies on the neuronal microtubule-associated protein Tau. We consider both the mechanistic details of Tau: the tubulin relationship and its aggregation process. Phosphorylation of Tau is intimately linked to both aspects. NMR spectroscopy has depicted accurate phosphorylation patterns by different kinases, and its non-destructive character has allowed functional assays with the same samples. Finally, we will discuss other post-translational modifications of Tau and its interaction with other cellular factors in relationship to its (dys)function. PMID:27338491

  15. NMR Based Diffusion Pore Imaging by Double Wave Vector Measurements

    CERN Document Server

    Kuder, Tristan Anselm

    2012-01-01

    In porous material research, one main interest of nuclear magnetic resonance (NMR) diffusion experiments is the determination of the exact shape of pores. It has been a longstanding ques-tion if this is achievable in principle. In this work, we present a method using short diffusion gradient pulses only, which is able to reveal the shape of arbitrary closed pores without rely-ing on a priori knowledge. In comparison to former approaches, the method has reduced de-mands on relaxation times and allows for a more flexible NMR sequence design, since, for example, stimulated echoes can be used.

  16. NMR Meets Tau: Insights into Its Function and Pathology

    Science.gov (United States)

    Lippens, Guy; Landrieu, Isabelle; Smet, Caroline; Huvent, Isabelle; Gandhi, Neha S.; Gigant, Benoît; Despres, Clément; Qi, Haoling; Lopez, Juan

    2016-01-01

    In this review, we focus on what we have learned from Nuclear Magnetic Resonance (NMR) studies on the neuronal microtubule-associated protein Tau. We consider both the mechanistic details of Tau: the tubulin relationship and its aggregation process. Phosphorylation of Tau is intimately linked to both aspects. NMR spectroscopy has depicted accurate phosphorylation patterns by different kinases, and its non-destructive character has allowed functional assays with the same samples. Finally, we will discuss other post-translational modifications of Tau and its interaction with other cellular factors in relationship to its (dys)function. PMID:27338491

  17. NMR investigation of intermetallic compound FeΛ2Sc

    International Nuclear Information System (INIS)

    Structure, macro- and microscopic magnetic properties of Fe12Sc intermetallides are studied. The structure of compounds has been determined roentgenographically using FeKsub(α) irradiation. NMR measurements have been carried out at 4.2 77 and 293 K and structure measurements - at 293 K. Fe2Sc samples magnetation, measured with the help of vibrational manometer in the 9 kOe field and in the temperature range from 293-1000 K, is equal to approximately 400 Gs (measurement accuracy approximately 3%). Curie temperature for Fe2Sc is determined according to the point of magnetization curve decay bend at high temperatures. Analysis of NMR spectra is carried out

  18. Biosynthetic origin of acetic acid using SNIF-NMR

    International Nuclear Information System (INIS)

    The main purpose of this work is to describe the use of the technique Site-Specific Natural Isotopic Fractionation of hydrogen (SNIF-NMR), using 2H and 1H NMR spectroscopy, to investigate the biosynthetic origin of acetic acid in commercial samples of Brazilian vinegar. This method is based on the deuterium to hydrogen ratio at a specific position (methyl group) of acetic acid obtained by fermentation, through different biosynthetic mechanisms, which result in different isotopic ratios. We measured the isotopic ratio of vinegars obtained through C3, C4, and CAM biosynthetic mechanisms, blends of C3 and C4 (agrins) and synthetic acetic acid. (author)

  19. Localized double-quantum-filtered 1H NMR spectroscopy

    Science.gov (United States)

    Thomas, M. A.; Hetherington, H. P.; Meyerhoff, D. J.; Twieg, D. B.

    The image-guided in vivo spectroscopic (ISIS) pulse sequence has been combined with a double-quantum-filter scheme in order to obtain localized and water-suppressed 1H NMR spectra of J-coupled metabolites. The coherence-transfer efficiency associated with the DQ filter for AX and A 3X spin systems is described. Phantom results of carnosine, alanine, and ethanol in aqueous solution are presented. For comparison, the 1H NMR spectrum of alanine in aqueous solution with the binomial (1331, 2662) spin-echo sequence is also shown.

  20. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

    Science.gov (United States)

    Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

    2016-06-13

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of