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Sample records for superscript 27al nmr

  1. Hydrolysis Studies and Quantitative Determination of Aluminum Ions Using [superscript 27]Al NMR: An Undergraduate Analytical Chemistry Experiment

    Science.gov (United States)

    Curtin, Maria A.; Ingalls, Laura R.; Campbell, Andrew; James-Pederson, Magdalena

    2008-01-01

    This article describes a novel experiment focused on metal ion hydrolysis and the equilibria related to metal ions in aqueous systems. Using [superscript 27]Al NMR, the students become familiar with NMR spectroscopy as a quantitative analytical tool for the determination of aluminum by preparing a standard calibration curve using standard aluminum…

  2. {sup 27}Al NMR studies of NpPd{sub 5}Al{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Chudo, H., E-mail: chudo.hiroyuki@jaea.go.j [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Sakai, H.; Tokunaga, Y.; Kambe, S. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Aoki, D.; Homma, Y.; Shiokawa, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Haga, Y.; Ikeda, S.; Matsuda, T.D. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Yasuoka, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2009-10-15

    We present {sup 27}Al NMR studies for a single crystal of the Np-based superconductor NpPd{sub 5}Al{sub 2}(T{sub c}=4.9K). We have observed a five-line {sup 27}Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T{sub c}. The temperature dependence of the {sup 27}Al nuclear spin-lattice relaxation rate shows no coherence peak below T{sub c}, indicating that NpPd{sub 5}Al{sub 2} is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd{sub 5}Al{sub 2}.

  3. Factor analysis of 27Al MAS NMR spectra for identifying nanocrystalline phases in amorphous geopolymers.

    Science.gov (United States)

    Urbanova, Martina; Kobera, Libor; Brus, Jiri

    2013-11-01

    Nanostructured materials offer enhanced physicochemical properties because of the large interfacial area. Typically, geopolymers with specifically synthesized nanosized zeolites are a promising material for the sorption of pollutants. The structural characterization of these aluminosilicates, however, continues to be a challenge. To circumvent complications resulting from the amorphous character of the aluminosilicate matrix and from the low concentrations of nanosized crystallites, we have proposed a procedure based on factor analysis of (27)Al MAS NMR spectra. The capability of the proposed method was tested on geopolymers that exhibited various tendencies to crystallize (i) completely amorphous systems, (ii) X-ray amorphous systems with nanocrystalline phases, and (iii) highly crystalline systems. Although the recorded (27)Al MAS NMR spectra did not show visible differences between the amorphous systems (i) and the geopolymers with the nanocrystalline phase (ii), the applied factor analysis unambiguously distinguished these materials. The samples were separated into the well-defined clusters, and the systems with the evolving crystalline phase were identified even before any crystalline fraction was detected by X-ray powder diffraction. Reliability of the proposed procedure was verified by comparing it with (29)Si MAS NMR spectra. Factor analysis of (27)Al MAS NMR spectra thus has the ability to reveal spectroscopic features corresponding to the nanocrystalline phases. Because the measurement time of (27)Al MAS NMR spectra is significantly shorter than that of (29)Si MAS NMR data, the proposed procedure is particularly suitable for the analysis of large sets of specifically synthesized geopolymers in which the formation of the limited fractions of nanocrystalline phases is desired. Copyright © 2013 John Wiley & Sons, Ltd.

  4. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  5. Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises

    Science.gov (United States)

    Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

    2012-01-01

    This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

  6. Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises

    Science.gov (United States)

    Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

    2012-01-01

    This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

  7. High-resolution /sup 27/Al NMR study of calcium aluminate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yakerson, V.I.; Nissenbaum, V.D.; Golosman, E.Z.; Mastikhin, V.M.

    1987-06-01

    The high-resolution /sup 27/Al NMR spectra of calcium aluminates, calcium hydroaluminates, and calcium alumina supports and catalysts have been studied. The structures of the anhydrous calcium aluminates (CaAl/sub 2/O/sub 3/, CaAl/sub 4/O/sub 7/, 3CaO x Al/sub 2/O/sub 3/, 12CaO x 7Al/sub 2/O/sub 3/, talyum) consist of aluminum-oxygen tetrahedra and contain various types of aluminum atoms, the nonequivalence of which increases in going from strongly basic to weakly basic aluminates. In the NMR spectrum the signal of octahedrally coordinated aluminum is due to disordered aluminum-oxygen structures. During the forming of the calcium-alumina catalysts and supports the process (AlO/sub 4/) ..-->.. (AlO/sub 6/) takes place during hydration, and (AlO/sub 6/) ..-->.. (AlO/sub 4/) during thermolysis; the nonequivalence of the tetrahedrally coordinated aluminum atoms decreases, while the (AlO/sub 4/):(AlO/sub 6/) ratio decreases as the degree of hydration increases.

  8. Combining (27)Al Solid-State NMR and First-Principles Simulations To Explore Crystal Structure in Disordered Aluminum Oxynitride.

    Science.gov (United States)

    Tu, Bingtian; Liu, Xin; Wang, Hao; Wang, Weimin; Zhai, Pengcheng; Fu, Zhengyi

    2016-12-19

    The nuclear magnetic resonance (NMR) technique gives insight into the local information in a crystal structure, while Rietveld refinement of powder X-ray diffraction (PXRD) sketches out the framework of a crystal lattice. In this work, first-principles calculations were combined with the solid-state NMR technique and Rietveld refinement to explore the crystal structure of a disordered aluminum oxynitride (γ-alon). The theoretical NMR parameters (chemical shift, δiso, quadrupolar coupling constants, CQ, and asymmetry parameter, η) of Al22.5O28.5N3.5, predicted by the gauge-including projector augmented wave (GIPAW) algorithm, were used to facilitate the analytical investigation of the (27)Al magic-angle spinning (MAS) NMR spectra of the as-prepared sample, whose formula was confirmed to be Al2.811O3.565N0.435 by quantitative analysis. The experimental δiso, CQ, and η of (27)Al showed a small discrepancy compared with theoretical models. The ratio of aluminum located at the 8a to 16d sites was calculated to be 0.531 from the relative integration of peaks in the (27)Al NMR spectra. The occupancies of aluminum at the 8a and 16d positions were determined through NMR investigations to be 0.9755 and 0.9178, respectively, and were used in the Rietveld refinement to obtain the lattice parameter and anion parameter of Al2.811O3.565N0.435. The results from (27)Al NMR investigations and PXRD structural refinement complemented each other. This work provides a powerful and accessible strategy to precisely understand the crystal structure of novel oxynitride materials with multiple disorder.

  9. 93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20

    Science.gov (United States)

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

    2015-03-01

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

  10. Solid-state {sup 27}Al and {sup 29}Si NMR investigations on Si-substituted hydrogarnets

    Energy Technology Data Exchange (ETDEWEB)

    Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Pena, P. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)]. E-mail: ppena@icv.csic.es; Aza, A.H. de [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, CSIC, Serrano Galvache, 4, 28033 Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain); Sanz, J. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

    2007-02-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} hydrates prepared by a reaction in the presence of D{sub 2}O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by {sup 29}Si and {sup 27}Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The {sup 29}Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} was followed by {sup 27}Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.

  11. Changes in Structural and Electronic Properties of the Zeolite Framework Induced by Extra-Framework Al and La in H-USY and La(x)NaY : A 29Si and 27Al MAS NMR and 27Al MQ MAS NMR Study

    NARCIS (Netherlands)

    Koningsberger, D.C.; Bokhoven, J.A. van; Roest, A.L.; Miller, J.T.; Nachtegaal, G.H,; Kentgens, A.

    2000-01-01

    A 27Al 3Q MAS, a quantitative 27Al MAS, and a 29Si MAS NMR study has been carried out on La(x)NaY and H-USY. Assignment of the different types of Al coordinations has been done using the results of the MQ MAS experiments. The 29Si MAS and 27Al MAS NMR results obtained at high fields (14.1 T) and

  12. Magnesium and Calcium Aluminate Liquids: In Situ High-Temperature 27Al NMR Spectroscopy.

    Science.gov (United States)

    Poe, B T; McMillan, P F; Coté, B; Massiot, D; Coutures, J P

    1993-02-05

    The use of high-temperature nuclear magnetic resonance (NMR) spectroscopy provides a means of investigating the structure of refractory aluminate liquids at temperatures up to 2500 K. Time-averaged structural information indicates that the average aluminum coordination for magnesium aluminate (MgAl(2)O(4)) liquid is slightly greater than for calcium aluminate (CaAl(2)O(4)) liquid and that in both liquids it is close to four. Ion dynamics simulations for these liquids suggest the presence of four-, five-, and six-coordinated aluminate species, in agreement with NMR experiments on fast-quenched glasses. These species undergo rapid chemical exchange in the high-temperature liquids, which is evidenced by a single Lorentzian NMR line.

  13. $^{11}$B and $^{27}$Al NMR spin-lattice relaxation and Knight shift study of Mg$_{1-x}$Al$_x$B$_2$. Evidence for anisotropic Fermi surface

    OpenAIRE

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

    2002-01-01

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

  14. Hydration kinetics for the alite, belite, and calcium aluminate phase in Portland cements from 27Al and 29Si MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Jensen, Ole Mejlhede; Jakobsen, Hans Jørgen

    1997-01-01

    29Si magic-angle spinning (MAS) NMR spectroscopy is shown to be a valuable tool for obtaining the quantities of alite and belite in hydrated Portland cements. The hydration (1-180 days) of a white Portland cement with 10 wt.% silica fume added is investigated and the degrees of hydration for alite...... belite, and silica fume are determined. It is demonstrated that 27Al MAS NMR spectra of hydrated Portland cements can give quantitative information about the formation of ettringite and the conversion of this phase to monosulphate during hydration....

  15. 11B and 27Al NMR spin-lattice relaxation and Knight shift of Mg1-xAlxB2: Evidence for an anisotropic Fermi surface

    Science.gov (United States)

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

    2002-10-01

    We report a detailed study of the 11B and 27Al NMR spin-lattice relaxation rates (1/T1) and the 27Al Knight shift (K) in Mg1-xAlxB2, 0<=x<=1. The evolution of (1/T1T) and K with x is in excellent agreement with the prediction of ab initio calculations of a highly anisotropic Fermi surface, consisting mainly of hole-type two-dimensional (2D) cylindrical sheets from bonding 2px,y boron orbitals. The density of states at the Fermi level also decreases sharply on Al doping and the 2D sheets collapse at x~0.55, where the superconducting phase disappears.

  16. High field 27Al MAS NMR and TPD studies of active sites in ethanol dehydration using thermally treated transitional aluminas as catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Xu, Suochang; Kwak, Ja Hun; Hu, Mary Y.; Wan, Chuan; Zhao, Zhenchao; Szanyi, Janos; Bao, Xinhe; Han, Xiuwen; Wang, Yong; Peden, Charles H. F.

    2016-04-01

    Gamma-, sigma- and theta-Al2O3 are well known metastable “transitional” alumina structural polymorphs. Upon heating, Al2O3 transitions to the so-called and Al2O3 polymorphs and finally forms the thermally stable Al2O3. The poorly developed crystallinity and co-existence of the , , and Al2O3 prior to forming all Al2O3, making it difficult to characterize the structures as well as to quantify the various phases of the transition alumina. As a result, there are significant controversies in the literatures. In this work, a detailed NMR analysis was carried out at high magnetic field on three special aluminum oxide samples where the, , , Al2O3 phases are made dominant, respectively, by controlling the synthesis conditions. The goal is to simplify, including making unambiguous, spectral assignments in 27Al MAS NMR spectra of transition alumina that have not yet been commonly agreed previously. Specifically, quantitative 1D 27Al MAS NMR was used to quantify the ratios of the different alumina structural units, 2D MQMAS 27Al MAS was used for obtaining the highest spectral resolution to guide the analysis of the 1D spectrum, and a saturation pulse sequence was integrated into the 1D NMR to select the amorphous structures, including obtain spectra where the penta-coordinate sites are observed with enhanced relative intensity. Collectively, this study uniquely assigns Al-peaks (both octahedral and tetrahedral) to the Al2O3 and the Al2O3 phases and offers a new way of understanding, including quantifying, the different structural units and sites in transition alumina samples.

  17. Extraction and [superscript 1]H NMR Analysis of Fats from Convenience Foods: A Laboratory Experiment for Organic Chemistry

    Science.gov (United States)

    Hartel, Aaron M.; Moore, Amy C.

    2014-01-01

    The extraction and analysis of fats from convenience foods (crackers, cookies, chips, candies) has been developed as an experiment for a second-year undergraduate organic chemistry laboratory course. Students gravimetrically determine the fat content per serving and then perform a [superscript 1]H NMR analysis of the recovered fat to determine the…

  18. Extraction and [superscript 1]H NMR Analysis of Fats from Convenience Foods: A Laboratory Experiment for Organic Chemistry

    Science.gov (United States)

    Hartel, Aaron M.; Moore, Amy C.

    2014-01-01

    The extraction and analysis of fats from convenience foods (crackers, cookies, chips, candies) has been developed as an experiment for a second-year undergraduate organic chemistry laboratory course. Students gravimetrically determine the fat content per serving and then perform a [superscript 1]H NMR analysis of the recovered fat to determine the…

  19. NMR Kinetics of the S[subscript N]2 Reaction between BuBr and I[superscript -]: An Introductory Organic Chemistry Laboratory Exercise

    Science.gov (United States)

    Mobley, T. Andrew

    2015-01-01

    A simple organic chemistry experiment is described that investigates the kinetics of the reaction between 1-bromobutane (BuBr) and iodide (I[superscript -]) as followed by observing the disappearance of BuBr and the appearance of 1-iodobutane (BuI) using [superscript 1]H NMR spectroscopy. In small groups of three to four, students acquire data to…

  20. NMR Kinetics of the S[subscript N]2 Reaction between BuBr and I[superscript -]: An Introductory Organic Chemistry Laboratory Exercise

    Science.gov (United States)

    Mobley, T. Andrew

    2015-01-01

    A simple organic chemistry experiment is described that investigates the kinetics of the reaction between 1-bromobutane (BuBr) and iodide (I[superscript -]) as followed by observing the disappearance of BuBr and the appearance of 1-iodobutane (BuI) using [superscript 1]H NMR spectroscopy. In small groups of three to four, students acquire data to…

  1. The structure of aluminosilicate glasses: High-resolution {sup 17}O and {sup 27}Al MAS and 3QMAS NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.K.; Stebbins, J.F.

    2000-05-04

    The authors investigate short-range order and local atomic configuration in charge-balanced aluminosilicate glasses as functions of composition, using {sup 17}O and {sup 27}Al MAS and triple-quantum magic angle spinning (3QMAS) NMR spectroscopy. Enhanced resolution in {sup 17}O and {sup 27}Al 3QMAS spectra, compared to MAS NMR, allows the quantification of the spectra and the extent of disorder using a semiempirical function relating 3QMAS efficiency to a quadrupolar coupling constant (C{sub q}). The variations with the Si/Al ratio (R) in peak positions and widths in the isotropic dimension of {sup 27}Al 3QMAS NMR spectra in both Na and Ca-aluminosilicate glasses can be ascribed to variations in the populations of Al sites with varying numbers of Al vs Si neighbors with composition. In the {sup 17}O 3QMAS spectra, variations of populations of three clearly resolved oxygen sites (Al-O-Al, Si-O-Al, and Si-O-Si) with R and cation field strength are consistent with the predictions given in previous results from {sup 29}Si MAS NMR. The quadrupolar coupling product (P{sub q}) of each oxygen site does not vary significantly with R, but it increases with cation field strength. On the other hand, isotropic chemical shifts ({delta}{sub iso}{sup CS}) increase with decreasing R and increasing cation field strength. These trends suggest that the configuration and framework connectivity in aluminosilicate glasses and melts are relatively constant with R but can be perturbed by high field strength cations with increased Al-O-Al and angular disorder, manifested by the increased variation of {delta}{sub iso}{sup CS} and the formation of non-bridging oxygen (NBO). The extent of disorder in aluminosilicate glasses is reflected in calculated configurational enthalpy, which increases with increasing cation field strength, consistent with the excess enthalpy of mixing data from calorimetry. The method and results given here provide improved prospects for the quantitative application of

  2. Friedel's salt formation in sulfoaluminate cements: A combined XRD and {sup 27}Al MAS NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paul, G. [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Boccaleri, E., E-mail: enrico.boccaleri@mfn.unipmn.it [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Buzzi, L.; Canonico, F. [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy); Gastaldi, D., E-mail: dgastaldi@buzziunicem.it [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy)

    2015-01-15

    Four different binders based on calcium sulfoaluminate cements have been submitted to accelerated chlorination through ionic exchange on hydrated pastes, in order to investigate their ability to chemically bind chloride ions that might reduce chloride penetration. The composition of hydrated cements before and after the treatment was evaluated by means of an X-Ray Diffraction–{sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy combined study, allowing to take into account even partially amorphous phases and to make quantitative assumption on the relative abundance of the different aluminium-containing phases. It was found that low SO{sub 3} Sulfoaluminate–Portland ternary systems are the most effective in binding chloride ions and the active role played by different members of the AFm family in chloride uptake was confirmed. Moreover, a peculiar behavior related to the formation of Friedel's salt in different pH conditions was also established for the different cements.

  3. Structure of shock compressed model basaltic glass: Insights from O K-edge X-ray Raman scattering and high-resolution 27Al NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Keun; Park, Sun Young; Kim, Hyo-Im; Tschauner, Oliver; Asimow, Paul; Bai, Ligang; Xiao, Yuming; Chow, Paul (UNLV); (SNU); (CIT); (CIW)

    2012-05-29

    The detailed atomic structures of shock compressed basaltic glasses are not well understood. Here, we explore the structures of shock compressed silicate glass with a diopside-anorthite eutectic composition (Di{sub 64}An{sub 36}), a common Fe-free model basaltic composition, using oxygen K-edge X-ray Raman scattering and high-resolution {sup 27}Al solid-state NMR spectroscopy and report previously unknown details of shock-induced changes in the atomic configurations. A topologically driven densification of the Di{sub 64}An{sub 36} glass is indicated by the increase in oxygen K-edge energy for the glass upon shock compression. The first experimental evidence of the increase in the fraction of highly coordinated Al in shock compressed glass is found in the {sup 27}Al NMR spectra. This unambiguous evidence of shock-induced changes in Al coordination environments provides atomistic insights into shock compression in basaltic glasses and allows us to microscopically constrain the magnitude of impact events or relevant processes involving natural basalts on Earth and planetary surfaces.

  4. High field 27Al MAS NMR and TPD studies of active sites in ethanol dehydration using thermally treated transitional aluminas as catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Xu, Suochang; Kwak, Ja Hun; Hu, Mary Y.; Wan, Chuan; Zhao, Zhenchao; Szanyi, Janos; Bao, Xinhe; Han, Xiuwen; Wang, Yong; Peden, Charles H. F.

    2016-04-01

    High field quantitative 27Al MAS NMR and temperature programmed desorption (TPD) of ethanol are used to study the surface and phase transformation of gamma-Al2O3 during calcination in the temperature range of 500 to 1300 degrees C. Following ethanol adsorption, ethylene is generated during TPD with a desorption temperature > 200 degrees C. With increasing calcination temperature prior to TPD, the amount of ethylene produced decreases monotonically. Significantly, 27Al MAS NMR reveals that the amount of penta-coordinate Al3+ ions (Lewis acid sites) also decreases with increasing calcination temperature. In fact, a strong correlation between the amount of penta-coordinate Al3+ ions and the amount of strongly adsorbed ethanol molecules (i.e., the ones that convert to ethylene during TPD) is obtained. This result indicates that the penta-coordinate aluminum sites are the catalytic active sites on alumina surfaces during ethanol dehydration reaction across the entire course of gamma- to alpha-Al2O3 phase transformations.

  5. Anomalous resonances in 29Si and 27Al NMR spectra of pyrope ([Mg,Fe]3Al2Si3O12) garnets: effects of paramagnetic cations.

    Science.gov (United States)

    Stebbins, Jonathan F; Kelsey, Kimberly E

    2009-08-28

    In oxide and silicate materials, particularly naturally-occurring minerals with contents of iron oxides greater than a few percent, paramagnetic impurities are well-known to broaden MAS NMR peaks, decrease relaxation times, and even cause overall loss of signal intensity. However, detection of resolved, discrete peaks that are shifted in frequency by nearby unpaired electron spins is rare in such systems. We report here high-resolution (27)Al and (29)Si spectra for synthetic and natural samples of pyrope garnet ([Mg,Fe](3)Al(2)Si(3)O(12)), the latter containing up to 3.5 wt% FeO. For both nuclides, spectra contain anomalous NMR peaks at frequencies that are 25 to 200 ppm from normal ranges, possibly through pseudocontact shifts induced by paramagnetic cations. Quantitation of peak areas suggests that signals from nuclides with such cations in their first shell may be broadened enough to be unobservable, while those with paramagnetics in their second cation shells may be substantially shifted. Overall spin-lattice relaxation rates are greatly enhanced by such impurities, and shifted resonances relax much faster than the unshifted main peaks. A high symmetry crystal structure (in this case cubic), which limits the number of different cation-cation distances in each shell, combined with a relatively low (non-cubic) symmetry for the sites hosting the magnetic cations, may be needed to readily detect such features.

  6. In-Situ Studies of Structure Transformation and Al Coordination of KAl(MoO42 during Heating by High Temperature Raman and 27Al NMR Spectroscopies

    Directory of Open Access Journals (Sweden)

    Min Wang

    2017-03-01

    Full Text Available Recent interest in optimizing composition and synthesis conditions of functional crystals, and the further exploration of new possible candidates for tunable solid-state lasers, has led to significant research on compounds in this family MIMIII(MVIO42 (MI = alkali metal, MIII = Al, In, Sc, Fe, Bi, lanthanide; MVI = Mo, W. The vibrational modes, structure transformation, and Al coordination of crystalline, glassy, and molten states of KAl(MoO42 have been investigated by in-situ high temperature Raman scattering and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR spectroscopy, together with first principles density functional simulation of room temperature Raman spectrum. The results showed that, under the present fast quenching conditions, Al is present predominantly in [AlO6] octahedra in both KAl(MoO42 glass and melt, with the tetrahedrally coordinated Al being minor at approximately 2.7%. The effect of K+, from ordered arrangement in the crystal to random distribution in the melt, on the local chemical environment of Al, was also revealed. The distribution and quantitative analysis of different Al coordination subspecies are final discussed and found to be dependent on the thermal history of the glass samples.

  7. [superscript 1]H NMR Spectroscopy-Based Configurational Analysis of Mono- and Disaccharides and Detection of ß-Glucosidase Activity: An Undergraduate Biochemistry Laboratory

    Science.gov (United States)

    Periyannan, Gopal R.; Lawrence, Barbara A.; Egan, Annie E.

    2015-01-01

    A [superscript 1]H NMR spectroscopy-based laboratory experiment explores mono- and disaccharide structural chemistry, and the enzyme-substrate specificity of glycosidic bond cleavage by ß-glucosidase towards cellobiose (ß-linked gluco-disaccharide) and maltose (a-linked gluco-disaccharide). Structural differences between cellobiose, maltose, and…

  8. A Discovery-Based Hydrochlorination of Carvone Utilizing a Guided-Inquiry Approach to Determine the Product Structure from [superscript 13]C NMR Spectra

    Science.gov (United States)

    Pelter, Michael W.; Walker, Natalie M.

    2012-01-01

    This experiment describes a discovery-based method for the regio- and stereoselective hydrochlorination of carvone, appropriate for a 3-h second-semester organic chemistry laboratory. The product is identified through interpretation of the [superscript 13]C NMR and DEPT spectra are obtained on an Anasazi EFT-60 at 15 MHz as neat samples. A…

  9. A Discovery-Based Hydrochlorination of Carvone Utilizing a Guided-Inquiry Approach to Determine the Product Structure from [superscript 13]C NMR Spectra

    Science.gov (United States)

    Pelter, Michael W.; Walker, Natalie M.

    2012-01-01

    This experiment describes a discovery-based method for the regio- and stereoselective hydrochlorination of carvone, appropriate for a 3-h second-semester organic chemistry laboratory. The product is identified through interpretation of the [superscript 13]C NMR and DEPT spectra are obtained on an Anasazi EFT-60 at 15 MHz as neat samples. A…

  10. [superscript 1]H NMR Spectroscopy-Based Configurational Analysis of Mono- and Disaccharides and Detection of ß-Glucosidase Activity: An Undergraduate Biochemistry Laboratory

    Science.gov (United States)

    Periyannan, Gopal R.; Lawrence, Barbara A.; Egan, Annie E.

    2015-01-01

    A [superscript 1]H NMR spectroscopy-based laboratory experiment explores mono- and disaccharide structural chemistry, and the enzyme-substrate specificity of glycosidic bond cleavage by ß-glucosidase towards cellobiose (ß-linked gluco-disaccharide) and maltose (a-linked gluco-disaccharide). Structural differences between cellobiose, maltose, and…

  11. Using a Problem Solving-Cooperative Learning Approach to Improve Students' Skills for Interpreting [Superscript 1]H NMR Spectra of Unknown Compounds in an Organic Spectroscopy Course

    Science.gov (United States)

    Angawi, Rihab F.

    2014-01-01

    To address third- and fourth-year chemistry students' difficulties with the challenge of interpreting [superscript 1]H NMR spectra, a problem solving-cooperative learning technique was incorporated in a Spectra of Organic Compounds course. Using this approach helped students deepen their understanding of the basics of [superscript 1]H NMR…

  12. Synthesis and NMR Spectral Analysis of Amine Heterocycles: The Effect of Asymmetry on the [superscript 1]H and [superscript 13]C NMR Spectra of N,O-Acetals

    Science.gov (United States)

    Saba, Shahrokh; Ciaccio, James A.; Espinal, Jennifer; Aman, Courtney E.

    2007-01-01

    The stereochemical investigation is conducted to give students the combined experience of chemical synthesis of amines and N-heterocycles and structural stereochemical analysis using NMR spectroscopy. Students are introduced to the concept of topicity-stereochemical relationships between ligands within a molecule by synthesizing N,O-acetals.

  13. Direct Observation of Lattice Aluminum Environments in Li Ion Cathodes LiNi1-y-zCoyAlzO2 and Al-Doped LiNixMnyCozO2 via (27)Al MAS NMR Spectroscopy.

    Science.gov (United States)

    Dogan, Fulya; Vaughey, John T; Iddir, Hakim; Key, Baris

    2016-07-06

    Direct observations of local lattice aluminum environments have been a major challenge for aluminum-bearing Li ion battery materials, such as LiNi1-y-zCoyAlzO2 (NCA) and aluminum-doped LiNixMnyCozO2 (NMC). (27)Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and nonlattice (i.e., surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aid of first-principles DFT calculations, we show direct evidence of lattice Al sites, nonpreferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum-"doped" NMC. Aluminum coordination of the paramagnetic (lattice) and diamagnetic (nonlattice) nature is investigated for Al-doped NMC and NCA. For the latter, the evolution of the lattice site(s) upon cycling is also studied. A clear reordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling.

  14. Pressure induced structural and density changes in Ca and Mg aluminosilicate glasses (MO/Al2O3≤1) recovered from 1-3 GPa: 27Al, 17O, 29Si MAS NMR and density

    Science.gov (United States)

    Bista, S.; Stebbins, J. F.

    2016-12-01

    Numerous studies have shown that at least in Na and K aluminosilicate melts and glasses, the presence of NBO facilitates the increase in Al coordination with pressure, for example albite and jadeite compositions show little structural change at 2-3 GPa. Much less is known about higher field strength cations such as Ca and Mg, despite their importance in mafic magmas. Therefore, in this study, we have studied several compositions of Ca and Mg aluminosilicate glasses with little to no NBO in the metaluminous and peraluminous regions. Our 27Al MAS NMR on the glasses recovered from high T and P show surprisingly rapid increases in average Al coordination with pressure, with the largest increases recorded in the Mg system. In Ca aluminosilicate glasses, the average Al coordination increase in peralkaline and peraluminous glasses follow a much more rapid rise compared to the metaluminous, although the metaluminous composition also shows a significant change in Al coordination unlike the Na aluminosilicate glasses of similar composition. In Mg aluminosilicate glasses, the average Al coordination increase in both peralkaline and metaluminous compositions are similar. Our study shows that the mechanism of the coordination increase with pressure is more complex than the simple consumption of NBO, especially with the high field strength and smaller size modifier cations like Mg. We also observed shifts in 29Si and 17O MAS NMR spectra suggesting increase in high coordinated Al neighbors, but these changes are harder to uniquely interpret.

  15. Why Is It so? The [superscript 1]H-NMR CH[subscript 2] Splitting in Substituted Propanes

    Science.gov (United States)

    Lim, Kieran F.; Dereani, Marino

    2010-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is an important tool in the structural analysis of both organic and inorganic molecules. Proton NMR spectra can yield information about the chemical or bonding environment surrounding various protons, the number of protons in those environments, and the number of neighbouring protons around each…

  16. Introducing NMR to a General Chemistry Audience: A Structural-Based Instrumental Laboratory Relating Lewis Structures, Molecular Models, and [superscript 13]C NMR Data

    Science.gov (United States)

    Pulliam, Curtis R.; Pfeiffer, William F.; Thomas, Alyssa C.

    2015-01-01

    This paper describes a first-year general chemistry laboratory that uses NMR spectroscopy and model building to emphasize molecular shape and structure. It is appropriate for either a traditional or an atoms-first curriculum. Students learn the basis of structure and the use of NMR data through a cooperative learning hands-on laboratory…

  17. Introducing NMR to a General Chemistry Audience: A Structural-Based Instrumental Laboratory Relating Lewis Structures, Molecular Models, and [superscript 13]C NMR Data

    Science.gov (United States)

    Pulliam, Curtis R.; Pfeiffer, William F.; Thomas, Alyssa C.

    2015-01-01

    This paper describes a first-year general chemistry laboratory that uses NMR spectroscopy and model building to emphasize molecular shape and structure. It is appropriate for either a traditional or an atoms-first curriculum. Students learn the basis of structure and the use of NMR data through a cooperative learning hands-on laboratory…

  18. Why Are [superscript 1]H NMR Integrations Not Perfect? An Inquiry-Based Exercise for Exploring the Relationship between Spin Dynamics and NMR Integration in the Organic Laboratory

    Science.gov (United States)

    Weizman, Haim

    2008-01-01

    When FT-NMR is used to collect data without a sufficient delay time between subsequent pulses, the integrated area under certain peaks may result in a lower value than should be observed under appropriate conditions. This discrepancy in integration may deceive the inexperienced eye and consequently can lead to a wrong assignment of the NMR…

  19. New transition metal-rich rare-earth palladium/platinum aluminides with RET{sub 5}Al{sub 2} composition. Structure, magnetism and {sup 27}Al NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Stegemann, Frank; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie

    2015-06-01

    REPd{sub 5}Al{sub 2} compounds with RE = Ce-Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements (RE = Tb-Yb) had not been prepared. We report on the missing members of the REPd{sub 5}Al{sub 2} (RE = Tb-Yb) series as well as on the new REPt{sub 5}Al{sub 2} (RE = Y, Gd-Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi{sub 2}Al{sub 5} type with an anti-arrangement of the T = Pd/Pt and Al atoms. YPd{sub 5}Al{sub 2} and LuPd{sub 5}Al{sub 2}, as well as the respective platinum homologs, YPt{sub 5}Al{sub 2} and LuPt{sub 5}Al{sub 2}, have been characterized also by {sup 27}Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.

  20. {sup 27}Al NMR/NQR study on RRu{sub 2}Al{sub 10} (R: La, Ce) and RFe{sub 2}Al{sub 10} (R: Y, Yb).

    Energy Technology Data Exchange (ETDEWEB)

    Khuntia, Panchanana; Baenitz, Michael; Sarkar, Rajib; Steglich, Frank [Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden (Germany); Strydom, Andre [Physics Department APK, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa)

    2011-07-01

    Ternary orthorhombic aluminides of RT{sub 2}Al{sub 10} type (R:Ce, Yb, T: Fe, Ru, Os) are currently attracting much interest because of a number of exotic properties such as anomalously high magnetic ordering temperatures in CeRu{sub 2}Al{sub 10} and CeOs{sub 2}Al{sub 10}, and strongly hybridized Kondo insulating state in CeFe{sub 2}Al{sub 10}. The Fe-Al systems are of special interest because YFe{sub 2}Al{sub 10} is claimed being located close to a Fe-based ferromagnetic instability at very low temperature. Here pronounced non Fermi liquid (NFL) phenomena are observed. For YbRh{sub 2}Si{sub 2} this NFL behaviour is associated to strong ferromagnetic fluctuations (see {sup 29}Si NMR). Our spin relaxation study on YFe{sub 2}Al{sub 10} gives strong evidence for Fe based ferromagnetic fluctuations evolving towards low temperature in small fields. YbFe{sub 2}Al{sub 10} is a weak Kondo coupled heavy fermion system where no traces of Fe-magnetism could be found.

  1. Analysis of energy autocorrelation functionsin dissipative heavy ion collision of 27Al+27Al

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The excitation functions were measured in the reaction of27Al+27Al at incidentenergies from 114 MeV to 127 MeV in steps of 200 keV. Thedetection angles were continuouslycovered from 10 to 57 in the laboratory system. Theenergy autocorrelation functions of the dissipativefragmentswere analyzed by using different approaches. The nonself-averaging oscillations in theexcitation functions were considered due to the angular momentum coherence and damping ofthe coherent nuclear rotation. The damping results from a quantum chaotic motion.

  2. Solid-state 27Al nuclear magnetic resonance investigation of three aluminum-centered dyes

    KAUST Repository

    Mroué, Kamal H.

    2010-02-01

    We report the first solid-state 27Al NMR study of three aluminum phthalocyanine dyes: aluminum phthalocyanine chloride, AlPcCl (1); aluminum-1,8,15,22-tetrakis(phenylthio)-29H,31H-phthalocyanine chloride, AlPc(SPh)4Cl (2); and aluminum-2,3-naphthalocyanine chloride, AlNcCl (3). Each of these compounds contains Al3+ ions coordinating to four nitrogen atoms and a chlorine atom. Solid-state 27Al NMR spectra, including multiple-quantum magic-angle spinning (MQMAS) spectra and quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) spectra of stationary powdered samples have been acquired at multiple high magnetic field strengths (11.7, 14.1, and 21.1 T) to determine their composition and number of aluminum sites, which were analyzed to extract detailed information on the aluminum electric field gradient (EFG) and nuclear magnetic shielding tensors. The quadrupolar parameters for each 27Al site were determined from spectral simulations, with quadrupolar coupling constants (CQ) ranging from 5.40 to 10.0 MHz and asymmetry parameters (η) ranging from 0.10 to 0.50, and compared well with the results of quantum chemical calculations of these tensors. We also report the largest 27Al chemical shielding anisotropy (CSA), with a span of 120 ± 10 ppm, observed directly in a solid material. The combination of MQMAS and computational predictions are used to interpret the presence of multiple aluminum sites in two of the three samples.

  3. Enzymatic Resolution of 1-Phenylethanol and Formation of a Diastereomer: An Undergraduate [superscript 1]H NMR Experiment to Introduce Chiral Chemistry

    Science.gov (United States)

    Faraldos, Juan A.; Giner, Jos-Luis; Smith, David H.; Wilson, Mark; Ronhovde, Kyla; Wilson, Erin; Clevette, David; Holmes, Andrea E.; Rouhier, Kerry

    2011-01-01

    This organic laboratory experiment introduces students to stereoselective enzyme reactions, resolution of enantiomers, and NMR analysis of diastereomers. The reaction between racemic 1-phenylethanol and vinyl acetate in hexane to form an ester is catalyzed by acylase I. The unreacted alcohol is then treated with a chiral acid and the resulting…

  4. [sup 27]Al nuclear magnetic resonance spectra of Ce[sub 3]Al[sub 11] at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Gavilano, J.L. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Hunziker, J. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Buechi, S. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Fisk, Z. (Los Alamos National Lab., Los Alamos, NM (United States)); Ott, H.R. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland))

    1994-02-01

    We have measured the [sup 27]Al nuclear magnetic resonance, NMR, spectra of oriented powder of the intermetallic compound Ce[sub 3]Al[sub 11] at temperatures between 0.03 K and 20 K, and frequencies of 2.815 MHz, 3.925 MHz, 9.208 MHz and 74.81 MHz. In the paramagnetic state the NMR spectra show the quadrupolar-split contribution of the four inequivalent Al-sites with strongly temperature-dependent Knigth shifts. The NMR spectra indicate the onset of a ferromagnetic phase below 6.2 K transforming into a sinusoidally modulated antiferromagnetic state below 3.3 K. (orig.)

  5. {sup 27}Al and {sup 45}Sc NMR spectroscopy on ScT{sub 2}Al and Sc(T{sub 0.5}T{sup '}{sub 0.5}){sub 2}Al (T = T{sup '} = Ni, Pd, Pt, Cu, Ag, Au) Heusler phases and superconductivity in Sc(Pd{sub 0.5}Au{sub 0.5}){sub 2}Al

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Niehaus, Oliver; Janka, Oliver [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany)

    2015-02-15

    The intermetallic Heusler compounds with ScT{sub 2}Al and Sc(T{sub 0.5}T{sup '}{sub 0.5}){sub 2}Al composition with T = T{sup '} = Ni, Pd, Pt, Cu, Ag, Au were synthesized from the elements by arc melting. They crystallize in the cubic MnCu{sub 2}Al type structure, space group Fm anti 3m. The unit cell parameters were determined by powder X-ray diffraction and the structure of Sc(Pd{sub 0.5}Au{sub 0.5}){sub 2}Al was refined on the basis of single-crystal X-ray diffraction. While the majority of the compounds show Pauli-paramagnetism, ScAu{sub 2}Al and the newly synthesized solid solution Sc(Pd{sub 0.5}Au{sub 0.5}){sub 2}Al exhibit superconductivity with transition temperatures of T{sub C} = 4.4 K and T{sub C} = 3.0(1) K, respectively. The superconducting state of Sc(Pd{sub 0.5}Au{sub 0.5}){sub 2}Al was also investigated by electrical resistivity measurements. All the synthesized compounds were furthermore studied by {sup 27}Al and {sup 45}Sc MAS-NMR spectroscopy. The resonance shifts of the synthesized compounds were determined and in Sc(Pd{sub 1-x}Au{sub x}){sub 2}Al a linear relationship between the resonance shifts and the composition was found. Line broadening effects and enhanced quadrupolar interaction strengths observed in the mixed samples can be attributed to the effect of Pd/Au mixing on the 8c Wyckoff site. The NMR spectroscopic data give no clear evidence for or against Sc/Al site disordering. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Do Humans Really Learn A[superscript n] B[superscript n] Artificial Grammars from Exemplars?

    Science.gov (United States)

    Hochmann, Jean-Remy; Azadpour, Mahan; Mehler, Jacques

    2008-01-01

    An important topic in the evolution of language is the kinds of grammars that can be computed by humans and other animals. Fitch and Hauser (F&H; 2004) approached this question by assessing the ability of different species to learn 2 grammars, (AB)[superscript n] and A[superscript n] B[superscript n]. A[superscript n] B[superscript n] was taken to…

  7. Experimental Progress on the NIST ^27Al^+ Optical Clock

    Science.gov (United States)

    Chou, Chin-Wen; Hume, David B.; Koelemeij, Jeroen C. J.; Rosenband, Till; Bergquist, James C.; Wineland, Dave J.

    2009-05-01

    A recent measurement of the frequency ratio between single-ion optical clocks based on ^27Al^+ and ^199Hg^+ at NIST showed a combined statistical and systematic uncertainty of 5.2 x 10-17[1]. Here we report progress on improving both the accuracy and stability of the ^27Al^+ optical clock. We have developed a new trap and laser systems that enable the use of ^25Mg^+ for sympathetic cooling and clock-state detection of ^27Al^+. These developments should reduce time-dilation shifts caused by harmonic motion of the ions and thus lower the dominant systematic uncertainty below 10-17. In the new clock apparatus we have demonstrated spectroscopy of the ^27Al^+ ^1S0 to ^3P0 transition with a quality factor of Q = 3.5 x 10^14 and simultaneously a contrast approaching unity. In addition, we have developed techniques for the sympathetic laser cooling and quantum logic spectroscopy of multiple aluminum ions with the goal of further improving measurement stability [2]. *supported by ONR and NIST [1] T. Rosenband et al., Science 319, 1808 (2008) [2] D. B. Hume et al., Phys. Rev. Lett. 99, 120502 (2007)

  8. 27Al scattering at low energies

    Science.gov (United States)

    Morcelle, V.; Lichtenthäler, R.; Lépine-Szily, A.; Guimarães, V.; Pires, K. C. C.; Lubian, J.; Mendes Junior, D. R.; de Faria, P. N.; Kolata, J. J.; Becchetti, F. D.; Jiang, H.; Aguilera, E. F.; Lizcano, D.; Martinez-Quiroz, E.; Garcia, H.

    2017-01-01

    We present 8B 27Al elastic scattering angular distributions for the proton-halo nucleus 8B at two energies above the Coulomb barrier, namely Elab=15.3 and 21.7 MeV. The experiments were performed in the Radioactive Ion Beams in Brasil facility (RIBRAS) in São Paulo, and in the TwinSol facility at the University of Notre Dame, USA. The angular distributions were measured in the angular range of 15-80 degrees. Optical model and continuum discretized coupled channels calculations were performed, and the total reaction cross sections were derived. A comparison of the 8B+27Al total reaction cross sections with similar systems including exotic, weakly bound, and tightly bound projectiles impinging on the same target is presented.

  9. 27Al nuclear quadrupole resonance study of crystalline aluminosilicates

    Science.gov (United States)

    Lee, Donghoon; Bray, P. J.

    27Al NQR responses have been obtained from the three different forms of crystalline Al 2SiO 5, andalusite, kyanite, and sillimanite, by a very sensitive Robinson-type continuous wave NQR spectrometer at 77 K or at room temperature. From the NQR responses the values of Qcc and of η were determined for all the aluminum coordinations in the powdered samples. The values are compared with those obtained by nuclear magnetic resonance studies of single crystals.

  10. The NIST 27 Al+ quantum-logic clock

    Science.gov (United States)

    Leibrandt, David; Brewer, Samuel; Chen, Jwo-Sy; Hume, David; Hankin, Aaron; Huang, Yao; Chou, Chin-Wen; Rosenband, Till; Wineland, David

    2016-05-01

    Optical atomic clocks based on quantum-logic spectroscopy of the 1 S0 3 P0 transition in 27 Al+ have reached a systematic fractional frequency uncertainty of 8 . 0 ×10-18 , enabling table-top tests of fundamental physics as well as measurements of gravitational potential differences. Currently, the largest limitations to the accuracy are second order time dilation shifts due to the driven motion (i.e., micromotion) and thermal motion of the trapped ions. In order to suppress these shifts, we have designed and built new ion traps based on gold-plated, laser-machined diamond wafers with differential RF drive, and we have operated one of our clocks with the ions laser cooled to near the six mode motional ground state. We present a characterization of the time dilation shifts in the new traps with uncertainties near 1 ×10-18 . Furthermore, we describe a new protocol for clock comparison measurements based on synchronous probing of the two clocks using phase-locked local oscillators, which allows for probe times longer than the laser coherence time and avoids the Dick effect. This work is supported by ARO, DARPA, and ONR.

  11. Spectroscopic factor strengths in $^{27}$Al(d,$^{3}$He)$^{26}$Mg and $^{27}$Al(d,$t$)$^{26}$Al reactions

    CERN Document Server

    Srivastava, P C

    2016-01-01

    In the present work we calculated spectroscopic factor strengths for recently measured experimental data for $1p$ and $1n$ pick-up reactions $^{27}$Al(d,$^{3}$He)$^{26}$Mg [Phys. Rev. C {\\bf 93}, 044601 (2016)] and $^{27}$Al( d,$t$)$^{26}$Al [Phys. Rev. C {\\bf 91}, 054611 (2015)] within the framework of the shell-model. We performed calculations with USDA and USDB effective interactions, results are in a good agreement with the experimental data.

  12. Detection of Fe[superscript 3+] and Al[superscript 3+] by Test Paper

    Science.gov (United States)

    Li, Lili; Xiang, Haifeng; Zhou, Xiangge; Li, Menglong; Wu, Di

    2012-01-01

    A porphyrin-based test paper has been designed and prepared. It can be used to analyze for Al[superscript 3+] and Fe[superscript 3+] in aqueous solution. An experiment employing the test paper can help students understand basic principles of spectrophotometry and how spectrophotometry is used in analyzing for metal ions. (Contains 1 scheme and 1…

  13. Molecular Orbitals of NO, NO[superscript+], and NO[superscript-]: A Computational Quantum Chemistry Experiment

    Science.gov (United States)

    Orenha, Renato P.; Galembeck, Sérgio E.

    2014-01-01

    This computational experiment presents qualitative molecular orbital (QMO) and computational quantum chemistry exercises of NO, NO[superscript+], and NO[superscript-]. Initially students explore several properties of the target molecules by Lewis diagrams and the QMO theory. Then, they compare qualitative conclusions with EHT and DFT calculations…

  14. Measurement of Angular Cross-Correlation of the Cross Section Fluctuation in Dissipative Collision 27Al+27Al%27Al+27Al耗散反应截面涨落的角度关联测量

    Institute of Scientific and Technical Information of China (English)

    胡鹏云; 王琦; 等

    2000-01-01

    27Al+27Al(Elab≈120MeV)耗散反应激发函数涨落的实验研究中,首次在较大的角度范围内获得截面涨落的角度关联系数和角度关联函数.实验结果表明,角度关联函数的形状呈现明显的非对称性,角度相干宽度至少为40°;截面涨落在前后角区表现出明显不同的角度相关性.

  15. Mechanical and wear behaviour of steel chips reinforced Zn27Al composites

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo ALANEME

    2016-12-01

    Full Text Available The mechanical and wear behaviour of Zn27Al alloy reinforced with steel machining chips (an industrial waste was investigated. Two step stir casting process was used to produce the Zn27Al based composites consisting of 5, 7.5 and 10 wt.% of the steel machining chips while unreinforced Zn27Al alloy and a composition consisting of 5 wt.% alumina were also prepared as control samples. Microstrutural analysis; mechanical and wear behaviour were assessed for these composites. The results show that the hardness and wear resistance of the composites increased with increase in weight percent of the steel chips from 5 to 10 wt.%. The UTS, strain to fracture, and the fracture toughness were however highest for the 5 wt.% steel chips reinforced composite grade; and decreased with increase in the weight percent of the steel chips from 5 to 10 wt.%. Generally the Zn27Al alloy based composites reinforced with steel machining chips, exhibited superior mechanical and wear properties in comparison to the unreinforced Zn27Al alloy and the 5 wt.% alumina reinforced Zn27Al alloy composite.

  16. CALCULATION OF THE DAMPING OF THE Zn-27Al ALLOY BASED ON THE MICRO INTERFACE SLIDING MODEL

    Institute of Scientific and Technical Information of China (English)

    Y.Z. Zhao; Q. Gao; Y.C. Liu

    2006-01-01

    The microstructures of the Zn-27Al alloy after modification, solid-solution treatment, and natural aging were studied. It was clarified why the damping properties of Zn-27Al alloys, after treatment,had advanced most on the basis of analyzing the microstructures. Approximate expressions have been educed, which can be used to quantificationally work out the damping of the Zn-27Al alloy on the basis of the micro interface sliding model. By comparing the testing damping properties of the foundry Zn-27Al alloys and the Zn-27Al alloys after modification, solid solution, and natural aging, it was shown that the expressions were rational.

  17. Sympathetic Ground State Cooling and Time-Dilation Shifts in an ^{27}Al^{+} Optical Clock.

    Science.gov (United States)

    Chen, J-S; Brewer, S M; Chou, C W; Wineland, D J; Leibrandt, D R; Hume, D B

    2017-02-03

    We report on Raman sideband cooling of ^{25}Mg^{+} to sympathetically cool the secular modes of motion in a ^{25}Mg^{+}-^{27}Al^{+} two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock-state distribution during the cooling process is studied using a rate-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of -(1.9±0.1)×10^{-18} for an ^{27}Al^{+} clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous ^{27}Al^{+} clocks.

  18. Sympathetic Ground State Cooling and Time-Dilation Shifts in an 27Al+ Optical Clock

    Science.gov (United States)

    Chen, J.-S.; Brewer, S. M.; Chou, C. W.; Wineland, D. J.; Leibrandt, D. R.; Hume, D. B.

    2017-02-01

    We report on Raman sideband cooling of 25Mg+ to sympathetically cool the secular modes of motion in a 25Mg+-27Al+ two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock-state distribution during the cooling process is studied using a rate-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of -(1.9 ±0.1 )×10-18 for an 27Al+ clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous 27Al+ clocks.

  19. Confirming the 3D Solution Structure of a Short Double-Stranded DNA Sequence Using NMR Spectroscopy

    Science.gov (United States)

    Ruhayel, Rasha A.; Berners-Price, Susan J.

    2010-01-01

    2D [superscript 1]H NOESY NMR spectroscopy is routinely used to give information on the closeness of hydrogen atoms through space. This work is based on a 2D [superscript 1]H NOESY NMR spectrum of a 12 base-pair DNA duplex. This 6-h laboratory workshop aims to provide advanced-level chemistry students with a basic, yet solid, understanding of how…

  20. Confirming the 3D Solution Structure of a Short Double-Stranded DNA Sequence Using NMR Spectroscopy

    Science.gov (United States)

    Ruhayel, Rasha A.; Berners-Price, Susan J.

    2010-01-01

    2D [superscript 1]H NOESY NMR spectroscopy is routinely used to give information on the closeness of hydrogen atoms through space. This work is based on a 2D [superscript 1]H NOESY NMR spectrum of a 12 base-pair DNA duplex. This 6-h laboratory workshop aims to provide advanced-level chemistry students with a basic, yet solid, understanding of how…

  1. Polymer Molecular Weight Analysis by [Superscript 1]H NMR Spectroscopy

    Science.gov (United States)

    Izunobi, Josephat U.; Higginbotham, Clement L.

    2011-01-01

    The measurement and analysis of molecular weight and molecular weight distribution remain matters of fundamental importance for the characterization and physical properties of polymers. Gel permeation chromatography (GPC) is the most routinely used method for the molecular weight determination of polymers whereas matrix-assisted laser…

  2. Polymer Molecular Weight Analysis by [Superscript 1]H NMR Spectroscopy

    Science.gov (United States)

    Izunobi, Josephat U.; Higginbotham, Clement L.

    2011-01-01

    The measurement and analysis of molecular weight and molecular weight distribution remain matters of fundamental importance for the characterization and physical properties of polymers. Gel permeation chromatography (GPC) is the most routinely used method for the molecular weight determination of polymers whereas matrix-assisted laser…

  3. 29Si,27Al Magic—Angle—Spinning Nuclear Magnetic Resonance(MAS NMR) Studies of Kaolinite and Its Thermal Transformation Products

    Institute of Scientific and Technical Information of China (English)

    何宏平; 胡澄; 等

    1995-01-01

    27Al,29Si MAS NMR studies of kaolinite and its thermal transformation products show that in the kaolinite-mullite reaction series there is an extensive segregation of Al2O3 and SiO2 and the reaction of Al2O3 with SiO2 to form mullite is the main path of mullite formation.At about 850°C,the peak intensity of Al(V) reaches its maximum and with the further rise of temperature the Al(V)signal completely disappears.At about 950°C,γ-Al2O3 accounts for about 71%of the material phases containing Al atoms.In the series there is no obvious presence of Al-Si spinel.The 27Al and 29Si MAS NMR spectra show that there is an obvious difference between the temperature points for Al-O2(OH)4 octahedral sheet collapsing and Si-O4 tetrahedral sheet breaking down.

  4. Activity-Dependent Excitability Changes Suggest Na[superscript +]/K[superscript +] Pump Dysfunction in Diabetic Neuropathy

    Science.gov (United States)

    Krishnan, Arun V.; Lin, Cindy S.-Y.; Kiernan, Matthew C.

    2008-01-01

    The present study was undertaken to evaluate the role of Na[superscript +]/K[superscript +] pump dysfunction in the development of diabetic neuropathy (DN). Nerve excitability techniques, which provide information about membrane potential and axonal ion channel function, were undertaken in 15 patients with established DN and in 10 patients with…

  5. Long-range angular correlation in dissipative reaction of 27Al+27A1

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Angular correlation of excitation functions in dissipative heavy ion collision 27Al+27A1 has been measured. The incident beam energies ranged from 114MeV to 127 MeV in steps of 200keV. The angular analysis region was continuous from 50° to 90° in the center of mass system. An angular coherent width, at least 40°, was obtained. This long-range angular correlation could not be interpreted in the framework of the standard statistical reaction theory with state of equilibrium or near equilibrium, maybe it reveals the formation of a new kind ofdissipative structure in the reaction of 27Al+27A1 with the state that is far from equilibrium.

  6. Proof without Words: (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1

    Science.gov (United States)

    Khattri, Sanjay Kumar

    2008-01-01

    We present a pictorial proof of the inequation (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1]. The inequation is also confirmed through the Taylor expansion and alternating series theorem.

  7. Proof without Words: (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1

    Science.gov (United States)

    Khattri, Sanjay Kumar

    2008-01-01

    We present a pictorial proof of the inequation (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1]. The inequation is also confirmed through the Taylor expansion and alternating series theorem.

  8. Structure of 26Al studied by one - nucleon transfer reaction 27Al(d,t

    Directory of Open Access Journals (Sweden)

    Srivastava Vishal

    2015-01-01

    Full Text Available The excited states of 26Al have been produced and studied using 27Al(d,t reaction with 25 MeV deuteron as projectile. Optical model potential parameters were extracted from the measured elastic scattering angular distribution. Zero range distorted wave Born approximation analysis for the ground and 0.223 MeV states of 26Al have been done. The spectroscopic factors calculated for these states are found to be in good agreement with the previously reported values.

  9. Excited states of 26Al studied via the reaction 27Al(d,t

    Directory of Open Access Journals (Sweden)

    Srivastava Vishal

    2016-01-01

    Full Text Available The reaction 27Al(d,t at 25 MeV was utilized to study the excited states of 26Al. The angular distributions of the observed excited states of 26Al were analyzed with zero range distorted wave Born approximation as well as by incorporating finite range correction parameters to extract spectroscopic factors. The two sets of extracted spectroscopic factors were compared with each other to see the effect of using finite range correction in the transfer form factor.

  10. 14N + 13C fusion cross sections and compound nucleus limitation in 27Al

    Science.gov (United States)

    Digregorio, D. E.; Gomez del Campo, J.; Chan, Y. D.; Ford, J. L. C., Jr.; Shapira, D.; Ortiz, M. E.

    1982-10-01

    Fusion cross sections for the 14N + 13C system have been measured by detecting the evaporation residues at five bombarding energies which correspond to high excitation energies in the compound nucleus: E*(27Al)=64-110 MeV. The 27Al nucleus can be populated by four different heavy-ion entrance channels-15N + 12C, 16O + 11B, 14N + 13C, and 17O + 10B-which are accessible to experimental measurements. Comparing the present data with those already existing for the above channels, it is found that for E*>60 MeV the curves E* vs Jcr for each system converge, which may be indicative of a limitation imposed by the compound nucleus. The data are discussed in terms of existing models for entrance channel and statistical yrast line limitations. The highest energy point also suggests the existence of a maximum absolute angular momentum limit of ~28ℏ. NUCLEAR REACTIONS 14N + 13C E(14N)=86.0, 103.8, 149.0, 161.3, and 180.0 MeV; measured d2σdΩdE for reaction products from Z=5 to 12. Extracted σfus, σD, σR.

  11. Mechanical and Corrosion Behaviour of Zn-27Al Based Composites Reinforced with Groundnut Shell Ash and Silicon Carbide

    OpenAIRE

    K.K. Alaneme; B.O. Fatile; J.O. Borode

    2014-01-01

    The mechanical and corrosion behaviour of Zn-27Al alloy based composites reinforced with groundnut shell ash and silicon carbide was investigated. Experimental test composite samples were prepared by melting Zn-27Al alloy with pre-determined proportions of groundnut ash and silicon carbide as reinforcements using double stir casting. Microstructural examination, mechanical properties and corrosion behaviour were used to characterize the composites produced. The results show that hardness and ...

  12. Study of $^{26}$Mg through 1p pick up reaction $^{27}$Al(d,$^{3}$He)

    CERN Document Server

    Srivastava, Vishal; Rana, T K; Manna, S; Kundu, S; Bhattacharya, S; Banerjee, K; Roy, P; Pandey, R; Mukherjee, G; Ghosh, T K; Meena, J K; Roy, T; Chaudhuri, A; Sinha, M; Saha, A K; Asgar, Md A; Dey, A; Roy, Subinit; Shaikh, Md M

    2015-01-01

    The even-even nucleus $^{26}$Mg has been studied through the reaction $^{27}$Al(d,$^{3}$He) at 25 MeV beam energy. The spectroscopic factors have been extracted upto 7.50 MeV excitation energy using local, zero range distorted wave Born approximation. The comparison of the spectroscopic factors have been done with previously reported values using the same reaction probe. The extracted spectroscopic factors for different excited states were found to be in good agreement with the previously reported values for the same. The present results were also compared with the predictions from shell model as well as rotational model. The analog states of $^{26}$Al and $^{26}$Mg were found to be in good agreement.

  13. M[superscript 2+]•EDTA Binding Affinities: A Modern Experiment in Thermodynamics for the Physical Chemistry Laboratory

    Science.gov (United States)

    O'Brien, Leah C.; Root, Hannah B.; Wei, Chin-Chuan; Jensen, Drake; Shabestary, Nahid; De Meo, Cristina; Eder, Douglas J.

    2015-01-01

    Isothermal titration calorimetry was used to experimentally determine thermodynamic values for the ethylenediaminetetraacetic acid (EDTA)(aq) + M[superscript 2+](aq) reactions (M[superscript 2+] = Ca[superscript 2+] and Mg[superscript 2+]). Students showed that for reactions in a N-(2-hydroxyethyl)piperazine-N"-ethanesulfonic acid (HEPES)…

  14. [sup 27]Al nuclear magnetic resonance spectra in CeAl[sub 3] at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hunziker, J. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Gavilano, J.L. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Buechi, S. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland)); Ott, H.R. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland))

    1994-02-01

    We have measured the nuclear magnetic resonance, NMR, spectra of CeAl[sub 3] at 3.964 MHz, 2.095 MHz and 0.937 MHz in the temperature range between 0.04 K and 20 K. The complicated NMR absorption line of CeAl[sub 3] powder is shown to have more than one component, corresponding to at least two inequivalent Al sites. Below 0.9 K the relative intensity of a broad asymmetric structure increases, and the width of the NMR spectrum shows a rapid increase. At fields of the order of two kilogauss the asymmetry is strongly supressed. The temperature dependence of the asymmetry and width of the spectrum below 0.9 K, can neither be explained in terms of a temperature dependent Knight shift nor in terms of conventional magnetic ordering. (orig.)

  15. Elastic scattering and fusion cross-sections in 7Li + 27Al reaction

    Indian Academy of Sciences (India)

    D Patel; S Santra; S Mukherjee; B K Nayak; P K Rath; V V Parkar; R K Choudhury

    2013-10-01

    With an aim to understand the effects of breakup and transfer channels on elastic scattering and fusion cross-sections in the 7Li + 27Al reaction, simultaneous measurement of elastic scattering angular distributions and fusion cross-sections have been carried out at various energies (lab = 8.0–16.0 MeV) around the Coulomb barrier. Optical model (OM) analysis of the elastic scattering data does not show any threshold anomaly or breakup threshold anomaly behaviour in the energy dependence of the real and imaginary parts of the OM potential. Fusion cross-section at each bombarding energy is extracted from the measured -particle evaporation energy spectra at backward angles by comparing with the statistical model prediction. Results on fusion cross-sections from the present measurements along with data from the literature have been compared with the coupled-channels predictions. Detailed coupled-channels calculations have been carried out to study the effect of coupling of breakup, inelastic and transfer, channels on elastic scattering and fusion. The effect of 1-stripping transfer coupling was found to be significant compared to that of the projectile breakup couplings in the present system.

  16. Concerning the Integral dx/x[superscript m] (1+x)

    Science.gov (United States)

    Walters, William; Huber, Michael

    2010-01-01

    Consider the integral dx/x[superscript m] (1+x). In the "CRC Standard Mathematical Tables," this integral can require repeated integral evaluations. Enter this integral into your favourite computer algebra system, and the results may be unrecognizable. In this article, we seek to provide a simpler evaluation for integrals of this form. We state up…

  17. Concerning the Integral dx/x[superscript m] (1+x)

    Science.gov (United States)

    Walters, William; Huber, Michael

    2010-01-01

    Consider the integral dx/x[superscript m] (1+x). In the "CRC Standard Mathematical Tables," this integral can require repeated integral evaluations. Enter this integral into your favourite computer algebra system, and the results may be unrecognizable. In this article, we seek to provide a simpler evaluation for integrals of this form. We state up…

  18. On-line. gamma. -ray investigation of the /sup 14/N + /sup 27/Al reaction at 30 Mev/u

    Energy Technology Data Exchange (ETDEWEB)

    Charvet, A.; Beraud, R.; Duffait, R.; Ollivier, T.; Meyer, M.; Kossakowski, R.; Andre, S.; Barneoud, D.; Foin, C.; Genevey, J.

    1985-03-01

    The cross-sections of target-like residues following the /sup 14/N+/sup 27/Al reaction at 30 MeV/u have been measured from in-beam and radioactive ..gamma..-ray spectra. The recoil velocities of some fragments have been estimated from the ..gamma..-ray Doppler broadening.

  19. Use of [superscript 1]H, [superscript 13]C, and [superscript 19]F-NMR Spectroscopy and Computational Modeling to Explore Chemoselectivity in the Formation of a Grignard Reagent

    Science.gov (United States)

    Hein, Sara M.; Kopitzke, Robert W.; Nalli, Thomas W.; Esselman, Brian J.; Hill, Nicholas J.

    2015-01-01

    A discovery-based Grignard experiment for a second-year undergraduate organic chemistry course is described. The exclusive Grignard reagent formed by the reaction of 1-bromo-4-fluorobenzene (1) with Mg is 4-fluorophenylmagnesium bromide (2), which is treated with either benzophenone or CO[subscript 2] to produce the corresponding fluorinated…

  20. Use of [superscript 1]H, [superscript 13]C, and [superscript 19]F-NMR Spectroscopy and Computational Modeling to Explore Chemoselectivity in the Formation of a Grignard Reagent

    Science.gov (United States)

    Hein, Sara M.; Kopitzke, Robert W.; Nalli, Thomas W.; Esselman, Brian J.; Hill, Nicholas J.

    2015-01-01

    A discovery-based Grignard experiment for a second-year undergraduate organic chemistry course is described. The exclusive Grignard reagent formed by the reaction of 1-bromo-4-fluorobenzene (1) with Mg is 4-fluorophenylmagnesium bromide (2), which is treated with either benzophenone or CO[subscript 2] to produce the corresponding fluorinated…

  1. Triple-quantum two-dimentional {sup 27}Al magic-angle spinning nuclear magnetic resonance spectroscopic study of aluminosilicate and aluminate crystals and glasses

    Energy Technology Data Exchange (ETDEWEB)

    Baltisberger, J.H. [Berea College, KY (United States); Xu, Z.; Stebbins, J.F. [Stanford Univ., CA (United States); Wang, S.H.; Pines, A. [Lawrence Berkeley National Lab., CA (United States)

    1996-07-31

    A new two-dimensional magic-angle spinning NMR experiment using multiple-quantum coherence of half-integer quadrupolar nuclei was used to study {sup 27}Al sites in crystalline samples of leucite (KAlSi{sub 2}O{sub 6}), anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}), and kyanite (Al{sub 2}SiO{sub 5}), as well as CaAl{sub 2}Si{sub 2}O{sub 8} glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field. Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle. Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced. In the aluminoborate glass, peaks for sites with different Al coordination numbers are well seperated. The lack of such features in CaAl{sub 2}Si{sub 2}O{sub 8} glass rules out the presence of significant quantities of AlO{sub 5} and AlO{sub 6} groups. 31 refs., 8 figs., 3 tabs.

  2. Low-energy resonances in sup 25 Mg(p,. gamma. ) sup 26 Al, sup 26 Mg(p,. gamma. ) sup 27 Al and sup 27 Al(p,. gamma. ) sup 28 Si

    Energy Technology Data Exchange (ETDEWEB)

    Iliadis, C.; Schange, T.; Rolfs, C.; Schroeder, U.; Somorjai, E.; Trautvetter, H.P.; Wolke, K. (Muenster Univ. (Germany, F.R.). Inst. fuer Kernphysik); Endt, P.M.; Kikstra, S.W. (Rijksuniversiteit Utrecht (Netherlands). Robert van de Graaff Lab.); Champagne, A.E. (Princeton Univ., NJ (USA). Dept. of Physics); Arnould, M.; Paulus, G. (Universite Libre de Bruxelles (Belgium). Inst. d' Astronomie et d' Astrophysique)

    1990-06-11

    Gamma-ray decay schemes have been measured with bare and Compton-suppressed Ge detectors at low-energy resonances (E{sub p}<340 keV) in the (p, {gamma}) reactions on {sup 25}Mg, {sup 26}Mg and {sup 27}Al. Althogether 58 new decay branches have been observed and a new {sup 26}Mg(p, {gamma}){sup 27}Al resonance has been found at E{sub p}=154.5{plus minus}1.0 keV. The new branchings lead to J{sup {pi}}; T determinations (or limitations) for two states in {sup 26}Al and four states in {sup 28}Si. The absolute strengths of the {sup 25}Mg(p, {gamma}){sup 26}Al and {sup 26}Mg(p, {gamma}){sup 27}Al resonances have also been obtained, and the uncertainties of the stellar rates, deduced from the available data for both reactions, are significantly reduced. Some astrophysical consequences are discussed. (orig.).

  3. Integral Representation of the Pictorial Proof of Sum of [superscript n][subscript k=1]k[superscript 2] = 1/6n(n+1)(2n+1)

    Science.gov (United States)

    Kobayashi, Yukio

    2011-01-01

    The pictorial proof of the sum of [superscript n][subscript k=1] k[superscript 2] = 1/6n(n+1)(2n+1) is represented in the form of an integral. The integral representations are also applicable to the sum of [superscript n][subscript k-1] k[superscript m] (m greater than or equal to 3). These representations reveal that the sum of [superscript…

  4. Integral Representation of the Pictorial Proof of Sum of [superscript n][subscript k=1]k[superscript 2] = 1/6n(n+1)(2n+1)

    Science.gov (United States)

    Kobayashi, Yukio

    2011-01-01

    The pictorial proof of the sum of [superscript n][subscript k=1] k[superscript 2] = 1/6n(n+1)(2n+1) is represented in the form of an integral. The integral representations are also applicable to the sum of [superscript n][subscript k-1] k[superscript m] (m greater than or equal to 3). These representations reveal that the sum of [superscript…

  5. Validation of nuclear reaction models of 180 MeV proton-induced fragmentation of {sup 27}Al

    Energy Technology Data Exchange (ETDEWEB)

    Sabra, M.S., E-mail: m.sabra@vanderbilt.edu [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37212 (United States); Clemens, M.A. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Weller, R.A.; Mendenhall, M.H. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37212 (United States); Barghouty, A.F. [NASA Marshall Space Flight Center, Huntsville, AL 35805 (United States); Malik, F.B. [Department of Physics, Southern Illinois University, Carbondale, IL 62901 (United States); Department of Physics, Washington University, St. Louis, MO 63130 (United States)

    2011-11-01

    Kinetic energy, angular distribution, and isobaric cross section data for A = 7-25 fragments formed in p + {sup 27}Al reaction at bombarding energy of 180 MeV are compared with the calculations of the Binary Cascade Model (BIC), the Cascade Exciton Model (CEM), JQMD/PHITS, as well as the Statistical Model with Final State Interaction (SMFSI). For completeness, the kinetic energy spectra of light particles (n, p, {alpha}) formed in p + {sup 27}Al reaction at bombarding energy of 156 MeV are also presented. A general agreement between the data and predictions of these models is found. However, disagreement with the data for the yields of light-mass fragments as well as near-target fragments is also found and discussed. The importance of this comparative study to simulation and analysis of radiation effects on microscopic electrical components operating in space is also discussed.

  6. Mechanical and Corrosion Behaviour of Zn-27Al Based Composites Reinforced with Groundnut Shell Ash and Silicon Carbide

    Directory of Open Access Journals (Sweden)

    K.K. Alaneme

    2014-06-01

    Full Text Available The mechanical and corrosion behaviour of Zn-27Al alloy based composites reinforced with groundnut shell ash and silicon carbide was investigated. Experimental test composite samples were prepared by melting Zn-27Al alloy with pre-determined proportions of groundnut ash and silicon carbide as reinforcements using double stir casting. Microstructural examination, mechanical properties and corrosion behaviour were used to characterize the composites produced. The results show that hardness and ultimate tensile strength of the hybrid composites decreased with increase in GSA content. Although the % Elongation somewhat decreased with increase the GSA content, the trend was not as consistent as that of hardness and tensile strength. The fracture toughness of the hybrid composites however, increased with increase in the GSA content of the composites. In 3.5 % NaCl solution, the composites were resistant to corrosion with some of the hybrid composite grades containing GSA exhibiting relatively superior corrosion resistance to the grades without GSA. In 0.3M H2SO4 solution, the composites were generally a bit more susceptible to corrosion (compared to 3.5 % NaCl solution, but the effect of GSA content on the corrosion resistance of the composites was not consistent for the Zn-27Al alloy based composites.

  7. Atomic scale structure of amorphous aluminum oxyhydroxide, oxide and oxycarbide films probed by very high field (27)Al nuclear magnetic resonance.

    Science.gov (United States)

    Baggetto, L; Sarou-Kanian, V; Florian, P; Gleizes, A N; Massiot, D; Vahlas, C

    2017-03-15

    The atomic scale structure of aluminum in amorphous alumina films processed by direct liquid injection chemical vapor deposition from aluminum tri-isopropoxide (ATI) and dimethyl isopropoxide (DMAI) is investigated by solid-state (27)Al nuclear magnetic resonance (SSNMR) using a very high magnetic field of 20.0 T. This study is performed as a function of the deposition temperature in the range 300-560 °C, 150-450 °C, and 500-700 °C, for the films processed from ATI, DMAI (+H2O), and DMAI (+O2), respectively. While the majority of the films are composed of stoichiometric aluminum oxide, other samples are partially or fully hydroxylated at low temperature, or contain carbidic carbon when processed from DMAI above 500 °C. The quantitative analysis of the SSNMR experiments reveals that the local structure of these films is built from AlO4, AlO5, AlO6 and Al(O,C)4 units with minor proportions of the 6-fold aluminum coordination and significant amounts of oxycarbides in the films processed from DMAI (+O2). The aluminum coordination distribution as well as the chemical shift distribution indicate that the films processed from DMAI present a higher degree of structural disorder compared to the films processed from ATI. Hydroxylation leads to an increase of the 6-fold coordination resulting from the trend of OH groups to integrate into AlO6 units. The evidence of an additional environment in films processed from DMAI (+O2) by (27)Al SSNMR and first-principle NMR calculations on Al4C3 and Al4O4C crystal structures supports that carbon is located in Al(O,C)4 units. The concentration of this coordination environment strongly increases with increasing process temperature from 600 to 700 °C favoring a highly disordered structure and preventing from crystallizing into γ-alumina. The obtained results are a valuable guide to the selection of process conditions for the CVD of amorphous alumina films with regard to targeted applications.

  8. Differential cross section measurements of {sup 27}Al(p,p{sup /}γ){sup 27}Al and {sup 27}Al(p,αγ){sup 24}Mg reactions in the energy range of 1.6–3.0 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Jokar, A., E-mail: arezajokar@gmail.com [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of); Kakuee, O.; Lamehi-Rachti, M. [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of); Sharifzadeh, N. [Payame Noor University, PO Box 19395-13697, Tehran (Iran, Islamic Republic of); Fathollahi, V. [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of)

    2015-11-01

    In this work measurement of differential cross sections of {sup 27}Al(p,p{sup /}γ){sup 27}Al (E{sub γ} = 844, 1014 keV) and {sup 27}Al(p,αγ){sup 24}Mg (E{sub γ} = 1369 keV) nuclear reactions in the proton energy range of 1.6–3.0 MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26 μg/cm{sup 2} Al onto a 129 μg/cm{sup 2} self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

  9. Assessing Cardiff University's Curricula Contribution to Sustainable Development Using the STAUNCH[superscript (RTM)] System

    Science.gov (United States)

    Lozano, Rodrigo; Peattie, Ken

    2011-01-01

    This article presents the results of the sustainable development curricula assessment undertaken at 19 of the 28 schools of Cardiff University using the Sustainability Tool for Assessing UNiversity's Curricula Holistically (STAUNCH[superscript (RTM)]. STAUNCH[superscript (RTM)] was developed with two objectives: (1) to systematically assess how…

  10. Construct Validity of the WISC-IV[superscript UK] with a Large Referred Irish Sample

    Science.gov (United States)

    Watkins, Marley W.; Canivez, Gary L.; James, Trevor; James, Kate; Good, Rebecca

    2013-01-01

    Irish educational psychologists frequently use the Wechsler Intelligence Scale for Children-Fourth U.K. Edition (WISC-IV[superscript UK]) in clinical assessments of children with learning difficulties. Unfortunately, reliability and validity studies of the WISC-IV[superscript UK] have not yet been reported. This study examined the construct…

  11. Phosphorylation of K[superscript +] Channels at Single Residues Regulates Memory Formation

    Science.gov (United States)

    Vernon, Jeffrey; Irvine, Elaine E.; Peters, Marco; Jeyabalan, Jeshmi; Giese, K. Peter

    2016-01-01

    Phosphorylation is a ubiquitous post-translational modification of proteins, and a known physiological regulator of K[superscript +] channel function. Phosphorylation of K[superscript +] channels by kinases has long been presumed to regulate neuronal processing and behavior. Although circumstantial evidence has accumulated from behavioral studies…

  12. Health Literacy Study Circles[superscript +]. Introduction: Overview, Planning, and Facilitation Tips

    Science.gov (United States)

    Rudd, Rima; Soricone, Lisa; Santos, Maricel; Zobel, Emily; Smith, Janet

    2005-01-01

    A Health Literacy Study Circle[superscript +] is a multi-session professional development activity for adult education practitioners, conducted by a facilitator. All the information and materials required to conduct each Health Literacy Study Circle[superscript +] is presented in two parts: this Introduction and the "Facilitator's Guide" for each…

  13. Using Email to Enable E[superscript 3] (Effective, Efficient, and Engaging) Learning

    Science.gov (United States)

    Kim, ChanMin

    2008-01-01

    This article argues that technology that supports both noncognitive and cognitive aspects can make learning more effective, efficient, and engaging (e[superscript 3]-learning). The technology of interest in this article is email. The investigation focuses on characteristics of email that are likely to enable e[superscript 3]-learning. In addition,…

  14. Teaching the Modes of Ca[superscript 2+] Transport between the Plasma Membrane and Endoplasmic Reticulum Using a Classic Paper by Kwan et al.

    Science.gov (United States)

    Liang, Willmann

    2009-01-01

    This teaching article uses the report by Kwan et al., "Effects of methacholine, thapsigargin, and La[superscript 3+] on plasmalemmal and intracellular Ca[superscript 2+] transport in lacrimal acinar cells," where the effects of Ca[superscript 2+]-mobilizing agents in regulating Ca[superscript 2+] fluxes were examined under various conditions.…

  15. Fission, total and neutron capture cross section measurements at ORELA for {sup 233}U, {sup 27}Al and natural chlorine

    Energy Technology Data Exchange (ETDEWEB)

    Guber, K.H.; Spencer, R.R.; Leal, L.C.; Larson, D.C.; Santos, G. Dos; Harvey, J.A.; Hill, N.W.

    1998-08-01

    The authors have made use of the Oak Ridge Electron Linear Accelerator (ORELA) to measure the fission cross section of {sup 233}U in the neutron energy range of 0.36 eV to {approximately} 700 keV. This paper reports integral data and average cross sections. In addition they measured the total neutron cross section of {sup 27}Al and natural chlorine, as well as the capture cross section of Al over an energy range from 100 eV up to about 400 keV.

  16. 27Al fourier-transform electron-spin-echo modulation of Cu 2+-doped zeolites A and X

    Science.gov (United States)

    Goldfarb, Daniella; Kevan, Larry

    Cu 2+-doped NaA, CaA, and NaX zeolites were studied using the electron-spin-echo modulation (ESEM) method. In both hydrated and dehydrated samples 27Al modulation has been observed. The time-domain ESEM traces were Fourier transformed and analyzed in the frequency domain. All FT-ESEM spectra of the hydrated samples showed a single peak at the Larmor frequency of 27Ai, indicating that the zeeman interaction is dominant and that the 27Al quadrupole and hyperfine interactions are relatively small. Considerable changes in the spectrum appear upon dehydration. Several frequencies significantly different from the Larmor frequency appear and the spectrum depends on the major cocation present. The major features of the spectra of the dehydrated zeolites could be theoretically reproduced, using exact diagonalization of the nuclear Hamiltonian, with relatively large isotropic hyperfine and quadrupole coupling constants. For example, in CuCaA and CuNaA zeolites the isotropic hyperfine constant is in the range of 0.2-0.5 and 0.8-1.0 MHz, respectively, with the quadrupole coupling constant in the range of 6-10 MHz for both.

  17. Quadrupolar magic angle spinning NMR spectra fitted using the Pearson IV function.

    Science.gov (United States)

    Mironenko, Roman M; Belskaya, Olga B; Talsi, Valentin P; Likholobov, Vladimir A

    2014-01-01

    The Pearson IV function was used to fit the asymmetric solid-state (27)Al NMR spectra of alumina based catalysts. A high convergence (correlation coefficient is no less than 0.997) between experimental and simulated spectra was achieved. The decomposition of the (27)Al NMR spectra of zinc/aluminum mixed oxides with different Zn/Al molar ratio revealed an increased fraction (6-9%) of pentacoordinated aluminum atoms in these oxides as compared to γ-Al2O3. As the Zn/Al ratio is raised, the fraction of [AlO6] octahedral units decreases, while the fraction of [AlO4] tetrahedra increases.

  18. Contributions of complete fusion and break-up–fusion to intermediate mass fragment production in the low energy interaction of 12C and 27Al

    CERN Document Server

    Förtsch, S V; Colleoni, P; Gadioli, E; Gadioli Erba, E; Mairani, A; Steyn, G F; Lawrie, J J; Smit, F D; Connell, S H; Fearick, R W; Thovhogi, T

    2007-01-01

    The measured spectra of a large number of intermediate mass fragments produced at a CM energy of about 110 MeV in the 27Al(12C, x) reaction as well as in its inverse reaction, 12C(27Al, x), are presented. The analysis of these data suggests that, at this energy, the main reaction mechanisms which contribute to the intermediate mass fragment emission are two-nucleus complete fusion and break-up–fusion reactions.

  19. Elastic scattering and reaction cross sections for {sup 8}B, {sup 7}Be + {sup 27}Al around the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Morcelle, V.; Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Faria, P.N.; Camargo, O.; Barioni, A.; Mendes Junior, D.R.; Condori, R. P.; Zamora, J.C.; Morais, M.C.; Pires, K.C.C.; Scarduelli, V.; Leistenschneider, E.; Zagatto, V.A.B. [Universidade de Sao Paulo (USP), SP (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Aguilera, E.F.; Martinez-Quiroz, E.; Lizcano, D. [Instituto Nacional de Investigaciones Nucleares, DF (Mexico); Kolata, J.; Lamm, L.O. [University of Notre Dame, Indiana (United States); Becchetti, F.; Jiang, H. [University of Michigan, Ann Arbor, MI (United States)

    2011-07-01

    Full text: The advent of radioactive beam production opened a new era in the nuclear physics, allowing the study of nuclei far from the beta stability line. One of the most interesting discoveries is the exotic structure of some of these unstable nuclei, which present the halo, such as {sup 6}He, {sup 11}Be, {sup 11}Li and others. During the last years, systems involving the neutron halo nuclei {sup 6}He have been extensively studied. In the case proton halo nuclei, on the other hand, the amount of available experimental data is very limited. The proton rich nucleus {sup 8}B is very interesting candidate as it has one proton very loosely bound (Sp = 138 KeV) to the {sup 7}Be core. Due to this low binding energy, the {sup 8}B is expected to be a proton halo and the dissociation {sup 8}B -- >{sup 7}Be+p in a collision {sup 8}B+target is expected to be very probable having a considerable effect in the total reaction cross section. We performed {sup 8}B+{sup 27}Al elastic scattering measurements at E{sub lab}= 16.0 and 22.0 MeV. The {sup 8}B beam has been produced by the reaction {sup 3}He({sup 6}Li,{sup 8}B)n and focused on a {sup 27}Al secondary target (2.1 mg/cm{sup 2}). Two experiments have been performed one at the RIBRAS system (Brazil) and another in Twinsol (USA). As the secondary beam is a cocktail of {sup 4}He, {sup 6}Li, {sup 7}Be, {sup 8}B particles, the {sup 7}Be+{sup 27}Al elastic angular distributions have been obtained as well. The elastic angular distributions were analyzed by optical model calculations, using Woods- Saxon potential and the total reaction cross sections have been obtained. The total reaction cross sections have been reduced using the Wong formula and the UFF equation being compared with others data from the literature. (author)

  20. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy

    Science.gov (United States)

    Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.

    2011-01-01

    With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…

  1. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy

    Science.gov (United States)

    Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.

    2011-01-01

    With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…

  2. 27 Al MAS NMR Studies of HBEA Zeolite at Low to High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Wan, Chuan; Vjunov, Aleksei; Wang, Meng; Zhao, Zhenchao; Hu, Mary Y.; Camaioni, Donald M.; Lercher, Johannes A.

    2017-06-01

    27Al single pulse (SP) MAS NMR spectra of HBEA zeolites with high Si/Al ratios of 71 and 75 were obtained at three magnetic field strengths of 7.05, 11.75 and 19.97 T. High field 27Al MAS NMR spectra acquired at 19.97 T show significantly improved spectral resolution, resulting in at least two well-resolved tetrahedral-Al NMR peaks. Based on the results obtained from 27Al MAS and MQMAS NMR acquired at 19.97 T, four different quadrupole peaks are used to deconvolute the 27Al SP MAS spectra acquired at vari-ous fields by using the same set of quadrupole coupling constants, asymmetric parameters and relative integrated peak intensities for the tetrahedral Al peaks. The line shapes of individual peaks change from typical quadrupole line shape at low field to essentially symmetrical line shapes at high field. We demonstrate that for fully hydrated HBEA zeolites the effect of second order quadrupole interaction can be ignored and quantitative spectral analysis can be performed by directly fitting the high field spectra using mixed Gaussian/Lorentzian line shapes. Also, the analytical steps described in our work allow direct assignment of spectral intensity to individual Al tetrahedral sites (T-sites) of zeolite HBEA. Finally, the proposed concept is suggested generally applicable to other zeo-lite framework types, thus, allowing a direct probing of Al distributions by NMR spectroscopic methods in zeolites with high confi-dence.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, R. [California Univ., Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)

    1993-07-01

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

  4. Fictive Temperature Effects on Non-Bridging Oxygen and Five-Coordinated Aluminum in Calcium Aluminosilicate Glasses: High Resolution 17O and 27Al NMR Spectroscopy

    Science.gov (United States)

    Thompson, L. M.; Stebbins, J. F.

    2012-12-01

    Despite the importance of aluminosilicate melts to both the geological and technological communities, the configurational changes with temperature remain poorly understood. However, configurational changes with temperature play an important role in changes in thermodynamic and transport properties, as well as offering insight into potential relationships between minor structural species such as non-bridging oxygen (NBO) and VAl (AlO5). A previous study indicated changes in VAl with temperature in multiple calcium aluminosilicate glasses, while changes in NBO were only observed on the metaluminous join (Stebbins et al., 2008). Here we have expanded this to look at two series of calcium aluminosilicate glasses crossing the metaluminous join on a constant SiO2 isopleth at multiple fictive temperatures. In all cases, the amount of VAl present increased with increasing fictive temperature, although the magnitude of the increase varied with larger increases in the peraluminous regions versus the peralkaline earth regions. Increases in NBO are also observed with increasing fictive temperature in the metaluminous and peraluminous regions. Comparison of these results with those from the earlier study suggests that the changes may be most pronounced in the regions where the deviation from conventional wisdom are at their peak (e.g., in the metaluminous region of alkaline earth aluminosilicate glasses). Comparison of the increases in VAl and NBO with increasing fictive temperature support previous suggestions (Thompson and Stebbins 2011; Thompson and Stebbins 2012) that multiple mechanisms must exist to produce excess VAl and NBO and that at least some of these mechanisms must be decoupled from each other.

  5. 29Si and 27AI MAS NMR Study of Alkali Feldspars

    Institute of Scientific and Technical Information of China (English)

    周玲棣; 郭九皋; 袁汉珍; 李丽云

    1994-01-01

    12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.

  6. Cross-Correlation of Excitation Functions for Different Fragments and Different Scattering Angles in 27Al(19F, x) y Reactions

    Institute of Scientific and Technical Information of China (English)

    HAN Jian-Long; WU He-Yu; LI Zhi-Chang; LU Xiu-Qin; ZHAO Kui; ZHOU Ping; LIU Jian-Cheng; XU Guo-Ji; Sergey Yu Kun; WANG Qi; BAI Zhen; DONG Yu-Chuan; LI Song-Lin; DUAN Li-Min; XU Hu-Shan; XU Hua-Gen; CHEN Ruo-Fu

    2008-01-01

    @@ Excitation functions have been measured for different projectile-like fragments produced in 27 Al(19 F,x)y reactions at incident energies from 110.25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctuations of the excitation functions are observed. The cross-correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle θcm have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion collision of 27 Al(19 F,x )y.

  7. Energy loss measurements of 63Cu, 28Si and 27Al heavy ions crossing thin Polyvinylchloride (PVC) foil

    Science.gov (United States)

    Dib, A.; Ammi, H.; Guesmia, A.; Msimanga, M.; Mammeri, S.; Hedibel, M.; Guedioura, B.; Pineda-Vargas, C. A.

    2015-11-01

    Experimental stopping data of, 63Cu, 28Si and 27Al heavy ions in thin Polyvinylchloride (H3C2Cl1) foil have been obtained over the 0.045-0.50 MeV/nucleon energy range. The measured energy losses were carried out by Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer. A continuous stopping power data obtained in this work are well fitted by our proposed semi-empirical formula and the results are compared to those calculated by LSS formula or generated by SRIM-2013 and MSTAR predictions. Calculations using our formula agree well with the obtained experimental stopping powers, while the LSS formula underestimates the experimental data in the whole investigated energy range. In this work a simple expression for electronic stopping power of heavy ions at low energy in solid targets is introduced. This formula is based on the Firsov and Lindhard-Sharff stopping power models with a small modification made to the original expression, by incorporating the effective charge of moving ions concept and with exponential fit function.

  8. A Wet-Lab Approach to Stereochemistry Using [superscript 31]P NMR Spectroscopy

    Science.gov (United States)

    Fenton, Owen S.; Sculimbrene, Bianca R.

    2011-01-01

    Understanding stereochemistry is an important and difficult task for students to master in organic chemistry. In both introductory and advanced courses, students are encouraged to explore the spatial relationships between molecules, but this exploration is often limited either to the lecture hall or the confines of the library. As such, we sought…

  9. Fluorescence Spectroscopy of tRNA[superscript Phe] Y Base in the Presence of Mg[superscript 2+] and Small Molecule Ligands

    Science.gov (United States)

    Kirk, Sarah R.; Silverstein, Todd P.; McFarlane Holman, Karen L.

    2008-01-01

    This laboratory project is one component of a semester-long advanced biochemistry laboratory course that uses several complementary techniques to study tRNA[superscript Phe] conformational changes induced by ligand binding. In this article we describe a set of experiments in which students use fluorescence spectroscopy to study tRNA[superscript…

  10. Incremental Validity of WISC-IV[superscript UK] Factor Index Scores with a Referred Irish Sample: Predicting Performance on the WIAT-II[superscript UK

    Science.gov (United States)

    Canivez, Gary L.; Watkins, Marley W.; James, Trevor; Good, Rebecca; James, Kate

    2014-01-01

    Background: Subtest and factor scores have typically provided little incremental predictive validity beyond the omnibus IQ score. Aims: This study examined the incremental validity of Wechsler Intelligence Scale for Children-Fourth UK Edition (WISC-IV[superscript UK]; Wechsler, 2004a, "Wechsler Intelligence Scale for Children-Fourth UK…

  11. Incremental Validity of WISC-IV[superscript UK] Factor Index Scores with a Referred Irish Sample: Predicting Performance on the WIAT-II[superscript UK

    Science.gov (United States)

    Canivez, Gary L.; Watkins, Marley W.; James, Trevor; Good, Rebecca; James, Kate

    2014-01-01

    Background: Subtest and factor scores have typically provided little incremental predictive validity beyond the omnibus IQ score. Aims: This study examined the incremental validity of Wechsler Intelligence Scale for Children-Fourth UK Edition (WISC-IV[superscript UK]; Wechsler, 2004a, "Wechsler Intelligence Scale for Children-Fourth UK…

  12. Opposing Actions of Chronic[Deta][superscript 9] Tetrahydrocannabinol and Cannabinoid Antagonists on Hippocampal Long-Term Potentiation

    Science.gov (United States)

    Hoffman, Alexander F.; Oz, Murat; Yang, Ruiqin; Lichtman, Aron H.; Lupica, Carl R.

    2007-01-01

    Memory deficits produced by marijuana arise partly via interaction of the psychoactive component, [Deta][superscript 9]-tetrahydrocannabinol ([Deta][superscript 9]-THC), with cannabinoid receptors in the hippocampus. Although cannabinoids acutely reduce glutamate release and block hippocampal long-term potentiation (LTP), a potential substrate for…

  13. Integrating the SOP[superscript 2] Model into the Flipped Classroom to Foster Cognitive Presence and Learning Achievements

    Science.gov (United States)

    Chen, Hsiu-Ling; Chang, Chiung-Yun

    2017-01-01

    This study explored student teachers' cognitive presence and learning achievements by integrating the SOP[superscript 2] Model in which self-study (S), online group discussion (O) and double-stage presentations (P[superscript 2]) were implemented in the flipped classroom. The research was conducted at a university in Taiwan with 31 student…

  14. Functional MRI and NMR spectroscopy of an operating gas-liquid-solid catalytic reactor.

    Science.gov (United States)

    Koptyug, Igor V; Lysova, Anna A; Kulikov, Alexander V; Kirillov, Valery A; Parmon, Valentin N; Sagdeev, Renad Z

    2005-02-01

    A dynamic in situ study of alpha-methylstyrene catalytic hydrogenation on a single catalyst pellet or in a granular bed is performed using 1H MRI and spatially resolved 1H NMR spectroscopy. Owing to reaction exothermicity, a reciprocating motion of the liquid front within the pellet accompanied by pellet temperature oscillations has been observed. Spatially resolved information on the reactant to product conversion within the catalyst bed has been obtained for a steady-state regime. Two-dimensional 27Al NMR images of alumina catalyst supports and other alumina-containing materials have been detected using moderate magnetic field gradients (80 G/cm) and a two-pulse spin-echo sequence. Temperature dependence of signal intensity and 27Al T1 time of alumina are considered as possible temperature sensors for NMR thermometry applications.

  15. High-temperature NMR study of zeolite Na-A: Detection of a phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, R.; Tijink, G.A.H.; Veeman, W.S.; Maesen, T.L.M.; van Lent, J.F. (Univ. of Nijmegen (Netherlands))

    1989-01-26

    The zeolite Linde 4A is studied by {sup 23}Na, {sup 27}al, and {sup 29}Si NMR at temperatures up to 953 K. {sup 23}Na NMR shows that the quadrupole interaction of sodium ions sited at 6-rings decreases when the temperature increases. With the aid of two-dimensional nutation and exchange experiments it can be shown that large-amplitude motions of the sodium ions, which in principle could explain a decrease of quadrupole interactions, do not occur. The decrease of the quadrupole interaction can be interpreted in terms of a phase transition. From a comparison of the NMR spectra of {sup 23}Na and {sup 27}Al it is concluded that the zeolite framework undergoes a major structural change upon increasing the temperature, before the sodium ions are displaced at higher temperatures. The exchange of sodium ions for potassium ions shifts this transition to higher temperatures.

  16. Structural investigation of aluminium doped ZnO nanoparticles by solid-state NMR spectroscopy.

    Science.gov (United States)

    Avadhut, Yamini S; Weber, Johannes; Hammarberg, Elin; Feldmann, Claus; Schmedt auf der Günne, Jörn

    2012-09-07

    The electrical conductivity of aluminium doped zinc oxide (AZO, ZnO:Al) materials depends on doping induced defects and grain structure. This study aims at relating macroscopic electrical conductivity of AZO nanoparticles with their atomic structure, which is non-trivial because the derived materials are heavily disordered and heterogeneous in nature. For this purpose we synthesized AZO nanoparticles with different doping levels and narrow size distribution by a microwave assisted polyol method followed by drying and a reductive treatment with forming gas. From these particles electrically conductive, optically transparent films were obtained by spin-coating. Characterization involved energy-dispersive X-ray analysis, wet chemical analysis, X-ray diffraction, electron microscopy and dynamic light scattering, which provided a basis for a detailed structural solid-state NMR study. A multinuclear ((27)Al, (13)C, (1)H) spectroscopic investigation required a number of 1D MAS NMR and 2D MAS NMR techniques (T(1)-measurements, (27)Al-MQMAS, (27)Al-(1)H 2D-PRESTO-III heteronuclear correlation spectroscopy), which were corroborated by quantum chemical calculations with an embedded cluster method (EEIM) at the DFT level. From the combined data we conclude that only a small part of the provided Al is incorporated into the ZnO structure by substitution of Zn. The related (27)Al NMR signal undergoes a Knight shift when the material is subjected to a reductive treatment with forming gas. At higher (formal) doping levels Al forms insulating (Al, H and C containing) side-phases, which cover the surface of the ZnO:Al particles and increase the sheet resistivity of spin-coated material. Moreover, calculated (27)Al quadrupole coupling constants serve as a spectroscopic fingerprint by which previously suggested point-defects can be identified and in their great majority be ruled out.

  17. Semi empirical formula for electronic stopping power determination of 24Mg, 27Al and 28Si ions crossing Formvar foil in the ion energy domain of LSS theory

    Science.gov (United States)

    Guesmia, A.; Ammi, H.; Mammeri, S.; Dib, A.; Pineda-Vargas, C. A.; Msimanga, M.; Hedibel, M.

    2014-03-01

    We have determined continuous stopping power of heavy ions in thin Formvar foil for 28Si, 27Al and 24Mg ions over an energy range of (0.1-0.5) MeV/nucleon. Heavy Ions Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer has been used to measure energy loss of charged particles in this thin absorber. Lindhard, Scharff and Schiott (LSS) theory compared with the corresponding determined stopping values in Formvar, shows significantly large deviations. However, a novel semi empirical expression has been proposed here and tested for better stopping power calculations at low velocity in the ion energy domain of LSS theory for 28Si, 27Al and 24Mg ions crossing thin Formvar foil. The results were compared to the obtained experimental stopping power data, predictions of LSS theory and also to those generated by SRIM-2010 computer code. The obtained results exhibit good agreement with experimental data.

  18. Complex fragment production in 50 MeV/A sup 197 Au + sup 12 C, sup 27 Al, and @Cu reactions

    Energy Technology Data Exchange (ETDEWEB)

    Peaslee, G.F.; Moretto, L.G.; Wozniak, G.J.

    1990-04-01

    Complex fragment (Z>6) production was studied in three reverse- kinematic reactions: 50 MeV/A {sup 197}Au + {sup 12}C, {sup 27}Al, and {sup nat}Cu. Typical inclusive cross sections are shown, as well as exclusive results for 2- , 3-, and higher-fold events. Reconstructing the source velocity of these fragments and using a simple incomplete fusion model gives a reliable measure of the impact parameter and excitation energy of the reactions producing these fragments. A clear progression from peripheral (cold) events to more central (very hot) events is seen as function of source velocity. The primary production of fragments in the {sup 197}Au + {sup 12}C and {sup 27}Al reactions is consistent with statistical emission from a thermalized source, up to approximately 5 MeV/A of excitation energy. For the {sup nat}Cu target, another significant source of fragment emission is observed. 20 refs., 15 figs.

  19. Disappearance of flow and the in-medium nucleon-nucleon cross section for {sup 64}Zn+{sup 27}Al collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Zhi-Yong He [Caen Univ., 14 (France). Lab. de Physique Corpusculaire]|[Academia Sinica, Lanzhou, GS (China). Inst. of Modern Physics; Peter, J.; Angelique, J.C.; Bizard, G.; Brou, R.; Cussol, D. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Auger, A.; Cabot, C.; Crema, E. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Buta, A. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire]|[Institute of Atomic Physics, Bucharest (Romania)] [and others

    1996-09-01

    Experimental measurement and theoretical comparison of collective flow can give important information about the nuclear equation of state (EOS) and the in-medium nucleon-nucleon cross section. Experimental measurements of {sup 64}Zn+{sup 27}Al collision from 35 to 79 MeV/u with the 4{pi} array MUR=TONNEAU are presented. The results are compared to BUU calculations. (K.A.).

  20. Microstructure and mechanical behavior of stir-cast Zn–27Al based composites reinforced with rice husk ash, silicon carbide, and graphite

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2017-04-01

    Full Text Available The microstructure and mechanical properties of Zn–27Al based composites reinforced with rice husk ash (RHA, silicon carbide (SiC, and graphite (Cg particles have been investigated. The Zn–27Al composites consisting of varied weight ratios of the reinforcing materials were produced using the stir casting process. Hardness test, tensile properties evaluation, fracture toughness determination, and microstructural examination, were used to characterize the composites produced. Results show that the microstructures of the composites are similar, consisting of the dendritic structure of the Zn–27Al alloy matrix with fine dispersion of the reinforcing particles. The hardness of the composites decreased with increase in the weight percent of RHA (and corresponding decrease in SiC weight percent in the reinforcement. The tensile strength and yield strength decreased slightly with increase in the weight ratio of RHA in the composites with a maximum of 8.5% and 9.6% reductions respectively observed for as much as 40% RHA (corresponding to 40% reduction in SiC in the hybrid reinforcement. Although some of the composite compositions containing RHA had slightly higher % elongation values compared with those without RHA, it was generally observed that the % elongation was invariant to the composite RHA content. The fracture toughness of the composites increases with increase in the weight percent of RHA with as much as a 20% increase obtained for as much as 40% RHA (corresponding to 40% reduction in SiC in the hybrid reinforcement.

  1. Training Scientific Thinking Skills: Evidence from an MCAT[superscript 2015]-Aligned Classroom Module

    Science.gov (United States)

    Stevens, Courtney; Witkow, Melissa R.

    2014-01-01

    The present study reports on the development and evaluation of a classroom module to train scientific thinking skills. The module was implemented in two of four parallel sections of introductory psychology. To assess learning, a passage-based question set from the medical college admissions test (MCAT[superscript 2015]) preview guide was included…

  2. An Analysis of Different Representations for Vectors and Planes in R[superscript 3]: Learning Challenges

    Science.gov (United States)

    Sandoval, Ivonne; Possani, Edgar

    2016-01-01

    The purpose of this paper is to present an analysis of the difficulties faced by students when working with different representations of vectors, planes and their intersections in R[superscript 3]. Duval's theoretical framework on semiotic representations is used to design a set of evaluating activities, and later to analyze student work. The…

  3. Aligning Cost Assessment with Community-Based Participatory Research: The Kin Keeper (superscript SM) Intervention

    Science.gov (United States)

    Meghea, Cristian Ioan; Williams, Karen Patricia

    2015-01-01

    The few existing economic evaluations of community-based health promotion interventions were reported retrospectively at the end of the trial. We report an evaluation of the costs of the Kin Keeper(superscript SM) Cancer Prevention Intervention, a female family-focused educational intervention for underserved women applied to increase breast and…

  4. Relativistic Momentum and Kinetic Energy, and E = mc[superscript 2

    Science.gov (United States)

    Hu, Ben Yu-Kuang

    2009-01-01

    Based on relativistic velocity addition and the conservation of momentum and energy, I present simple derivations of the expressions for the relativistic momentum and kinetic energy of a particle, and for the formula E = mc[superscript 2]. (Contains 5 footnotes and 2 figures.)

  5. LE[superscript 3]AD Academy Builds Professionalism in Vocational Students

    Science.gov (United States)

    Hall, Candace

    2012-01-01

    Principal David Wheeler of Southeastern Regional Vocational-Technical High School founded LE[superscript 3]AD Academy--an innovative program that gives students the opportunity to build and run their own town in teams and with guidance from teachers. The program started in the spring of 2011, and it is innovative in many ways. The students' main…

  6. 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.

  7. Optical and scintillation properties of ce-doped (Gd2Y1)Ga2.7Al2.3O12 single crystal grown by Czochralski method

    Science.gov (United States)

    Wang, Chao; Wu, Yuntao; Ding, Dongzhou; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Ren, Guohao

    2016-06-01

    Multicomponent garnets, due to their excellent light yield and energy resolution, become one of the most promising scintillators used for homeland security and nuclear non-proliferation applications. This work focuses on the optimization of Ce-doped (Gd,Y)3(Ga,Al)5O12 scintillators using a combination strategy of pre-screening and scale-up. Ce-doped GdxY1-xGayAl5-yO12 (x=1, 2 and y=2, 2.2, 2.5, 2.7, 3) polycrystalline powders were prepared by high-temperature solid state reaction method. The desired garnet phase in all the samples was confirmed using X-ray diffraction measurement. By comparing the radioluminescence intensity, the highest scintillation efficiency was achieved at a component of Gd2Y1Ga2.7Al2.3O12:Ce powders. A (Gd2Y1)Ga2.7Al2.3O12 doped with 1% Ce single crystal with dimensions of Ø35×40 mm was grown by Czochralski method using a oriented seed. Luminescence and scintillation properties were measured. An optical transmittance of 84% was achieved in the concerned wavelength from 500 to 800 nm. Its 5d-4f emission of Ce3+ is at 530 nm. The light yield of a Ce1%: Gd2Y1Ga2.7Al2.3O12 single crystal slab at a size of 5×5×1 mm3 can reach about 65,000±3000 Ph/MeV along with two decay components of 94 and 615 ns under 137Cs source irradiation.

  8. Fusion near and below the barrier for the systems 32,34S+24,25,26Mg and 32S+27Al

    Science.gov (United States)

    Berkowitz, G. M.; Braun-Munzinger, P.; Karp, J. S.; Freifelder, R. H.; Renner, T. R.; Wilschut, H. W.

    1983-08-01

    Excitation functions are reported for total fusion near and below the Coulomb barrier of the systems 32,34S+24,25,26Mg and 27Al. The data cannot be reproduced by one-dimensional barrier penetration calculations. The enhancement of the cross sections at low energies is compared to predictions of models taking into acount the static deformation or zero point vibration of the reaction partners. Calculations including zero point motion do not reproduce the observed variations of the measured cross sections with respect to the neutron number of target and projectile. Reasonable agreement is obtained when calculating fusion between statically deformed nuclei. Finally, the fusion process is described in a quantum mechanical coupled channels model, indicating the importance of dynamical effect on sub-barrier fusion. NUCLEAR REACTIONS 24,25,26Mg, 27Al(32,34S, Fusion) 0.9

  9. Applications of the Theorem of Pythagoras in R[superscript 3

    Science.gov (United States)

    Srinivasan, V. K.

    2010-01-01

    Three distinct points A = (a, 0, 0) B = (0, b, 0) and (c, 0, 0) with abc not equal to 0 are taken, respectively on the "x", "y" and the "z"-axes of a rectangular coordinate system in R[superscript 3]. Using the converse of the theorem of Pythagoras, it is shown that the triangle [delta]ABC can never be a right-angled triangle. The result seems to…

  10. NMR GHZ

    CERN Document Server

    Laflamme, R; Zurek, W H; Catasti, P; Mariappan, S V S

    1998-01-01

    We describe the creation of a Greenberger-Horne-Zeilinger (GHZ) state of the form |000>+|111> (three maximally entangled quantum bits) using Nuclear Magnetic Resonance (NMR). We have successfully carried out the experiment using the proton and carbon spins of trichloroethylene, and confirmed the result using state tomography. We have thus extended the space of entangled quantum states explored systematically to three quantum bits, an essential step for quantum computation.

  11. Test Review: Wechsler, D. (2014),"Wechsler Intelligence Scale for Children, Fifth Edition: Canadian 322 (WISC-V[superscript CDN])." Toronto, Ontario: Pearson Canada Assessment.

    Science.gov (United States)

    Cormier, Damien C.; Kennedy, Kathleen E.; Aquilina, Alexandra M.

    2016-01-01

    The Wechsler Intelligence Scale for Children, Fifth Edition: Canadian (WISC-V[superscript CDN]; Wechsler, 2014) is published by Pearson Canada Assessment. The WISC-V[superscript CDN] is a norm-referenced, individually administered intelligence battery that provides a comprehensive diagnostic profile of the cognitive strengths and weaknesses of…

  12. Partial cross section of projectile fragmentation in {sup 197}Au+{sup 27}Al interactions at 1.015 GeV/n

    Energy Technology Data Exchange (ETDEWEB)

    Battacharyya, D.P.; Saha, S.; Basu, B. [Indian Association for the Cultivation of Science, Calcutta (India)] [and others

    1996-02-01

    The large fragmentation of {sup 197}Au projectiles at BEVALAC energy 1.015 GeV/n in Al target has been studied using a stack consisting of CR-39 (DOP) plastic track detectors. The partial cross-sections for the production of large fragments of charge Z{sub F} = 75 to Z{sub F} = 78 in collisions of {sup 197}Au beam of nuclei at 0.930 GeV/n in {sup 27}Al target has been estimated from the cone length distribution. The authors data found comparable to the expected results from the latest semi empirical model of Tsao et al. and that from the abrasion-ablation model of Townsend et al. The present data is in approximate agreement with the active and passive experimental data of Binns et al., and Gerbier et al. in Al target, respectively.

  13. The fusion dynamics for a positive Q-value system: $^{27}$Al+$^{45}$Sc using SEDF and role of spin-orbit interaction potential

    CERN Document Server

    Verma, Dalip Singh

    2016-01-01

    The fusion dynamics for a positive Q-value systems: $^{27}$Al+$^{45}$Sc, at near and deep sub-barrier energies has been investigated using the proximity potentials of Skyrme energy density formalism in semi classical extended Thomas Fermi approach for arbitrarily chosen Skyrme forces: SLy4, SIV, SGII and Proximity77 of Blocki and co-workers. The calculated fusion excitation functions for the proximity potentials obtained for Skyrme forces mentioned above and for the Proximity77 have been compared with experimental data. The proximity potential for Skyrme force SIV is found to be the best and is used in the calculations of the quantities like logarithmic derivative, barriers distributions and $S$-factor. Further, the role of spin-orbit interaction potential in the fusion dynamics of this system has been investigated.

  14. Improving tensile properties of dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy by low temperature high speed extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, T., E-mail: s123055@stn.nagaokaut.ac.jp [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan); Mezaki, T.; Xu, C.; Oh-ishi, K. [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan); Shimizu, K.; Hanaki, S. [Sankyo Tateyama, Inc., Sankyo Material-Company, 8-3, Nagonoe, Imizu, Toyama 934-8515 (Japan); Kamado, S. [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan)

    2015-11-05

    As-cast Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was extruded at temperatures from 350 °C to 500 °C. We examined the microstructural changes during extrusion at different temperatures to clarify dynamic recrystallization mechanisms during extrusion, and also investigated the effect of extrusion temperature on microstructures and mechanical properties of the alloy. High extrusion exit speed of 60 m/min was successfully achieved at wide range of temperatures from 350 °C to 500 °C even when as-cast dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was used as a billet for the extrusion. The extrusion at low temperature refines grain size and weakens basal texture due to continuous dynamic recrystallization (CDRX) together with double twinning. As a result, the alloy sample extruded at 350 °C exhibits higher tensile proof stress of 206 MPa and higher tensile ductility of 29% than T5-treated 6063 aluminum alloy and commercial AZ31 magnesium alloy even in an as-extruded condition. Furthermore, Hall–Petch coefficient for compressive proof stress is 1.8 times larger than that for tensile one, resulting in improvement of yield stress anisotropy (compressive proof stress/tensile yield stress ratio). - Highlights: • Dilute Mg–Al–Ca–Mn alloy can be extruded at high die-exit speed of 60 m/min. • The extrusion at low temperature refines recrystallized grain size and weakens basal texture. • Grain refining improves mechanical properties of dilute Mg–Al–Ca–Mn alloys.

  15. Effect of thermal annealing on scintillation properties of Ce:Gd2Y1Ga2.7Al2.3O12 under different atmosphere

    Science.gov (United States)

    Wang, Chao; Ding, Dongzhou; Wu, Yuntao; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Wang, Qingqing; Ye, Le; Ren, Guohao

    2017-05-01

    Cerium-doped 1% Ce:Gd2Y1Ga2.7Al2.3O12(GYGAG) single crystal samples grown via Czochralski method were annealed under air, O2 and N2 atmospheres from 350 to 1400 °C. The X-ray excited luminescence spectra, energy spectra and UV as well as thermally stimulated luminescence (TSL) spectra were performed comparatively on "as-grown" and thermally annealed samples. It was found that the luminescence efficiency after annealing in air and O2 was significantly enhanced compared to the non-annealed samples and this phenomenon was suggested to be caused by the existence of some oxygen vacancies in the Ce:GYGAG crystals. And the oxygen vacancies in the as-grown GYGAG crystals can be effectively eliminated by means of annealing in O2 containing atmosphere without changing the luminescence mechanism. From the TSL curves before and after annealing, three traps within 77-650 K were found to be related to oxygen vacancies.

  16. Reaction cross sections and elastic scattering energy dependence around the Coulomb barrier for the {sup 7}Be+{sup 27}Al system

    Energy Technology Data Exchange (ETDEWEB)

    Morcelle, Viviane; Gomes, P.R.S.; Lubian, J.; Mendes Junior, D.R. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Camargo, O.; Faria, P.N. de; Gasquez, L.; Morais, M.C.; Condori, R.P.; Pires, K.C.C.; Scarduelli, V. [Universidade de Sao Paulo (USP), SP (Brazil); Barioni, A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Zamora, J.C. [Technische Universitaet Darmstadt (Germany); Aguilera, E.; Martinez-Quiroz, E. [Instituto Nacional de Investigaciones Nucleares (Mexico); Kolata, J.; Jiang, H. [University of Notre Dame, IN (United States); Bechetti, F.D.; Lamm, L.O. [Michigan University, MI (United States); Lizcano, D. [Universidad Autonoma del Estado de Mexico (Mexico)

    2012-07-01

    Full text: Elastic scattering measurements were performed at energies around the Coulomb barrier at the Tandem Accelerators of the Sao Paulo (USP - Brazil ) and Notre Dame (UND - USA) Universities. The {sup 7}Be is a radioactive nucleus and has been produced by the reaction {sup 6}He({sup 6}Li,{sup 9}Be) and impinged on {sup 27}Al and {sup 197}Au secondary targets using a double superconducting systems RIBRAS ( USP ) and Twinsol (UND). The elastic scattering angular distributions were analyzed through the optical model calculations, using the Woods- Saxon form factors [1] and the Sao Paulo potential [2] to fit the experimental data. The total reaction cross sections were also derived and compared with others presented at the literature for other systems. In addition, a study of the nuclear potential energy dependence has been carried out in this work in the dispersion relation context. Due to the fact that {sup 7}Be has a small breakup threshold energy, the results can provide significant information of the influence of the breakup channel on the reactions involving this projectile. For this purpose, {chi}{sup 2}- data analysis with different kind of potentials were performed to identify the energy dependence of the real (V) and imaginary (W) parts of the potential. [1] L.C. Chamon et al., Phys. Rev. C 66, (2002) 014610. [2] R.D. Wood e D.S. Saxon, Phys. Rev. 95 ( 1954) 577. (author)

  17. Study of the A(e,e'$\\pi^+$) Reaction on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au

    Energy Technology Data Exchange (ETDEWEB)

    Qian, X; Clasie, B; Arrington, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Christy, M E; Chudakov, E; Dalton, M M; Daniel, A; Day, D; Dutta, D; El Fassi, L; Ent, R; Fenker, H C; Ferrer, J; Fomin, N; Gao, H; Garrow, K; Gaskell, D; Gray, C; Huber, G M; Jones, M K; Kalantarians, N; Keppel, C E; Kramer, K; Li, Y; Liang, Y; Lung, A F; Malace, S; Markowitz, P; Matsumura, A; Meekins, D G; Mertens, T; Miyoshi, T; Mkrtchyan, H; Monson, R; Navasardyan, T; Niculescu, G; Niculescu, I; Okayasu, Y; Opper, A K; Perdrisat, C; Punjabi, V; Rauf, A W; Rodriquez, V M; Rohe, D; Seely, J; Segbefia, E; Smith, G R; Sumihama, M; Tadevosyan, V; Tang, L; Villano, A; Vulcan, W F; Wesselmann, F R; Wood, S A; Yuan, L; Zheng, X

    2010-05-01

    Cross sections for the p($e,e'\\pi^{+}$)n process on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the nuclear transparencies. Data were taken for four-momentum transfers ranging from $Q^2$=1.1 to 4.8 GeV$^2$ for a fixed center of mass energy of $W$=2.14 GeV. The ratio of $\\sigma_L$ and $\\sigma_T$ was extracted from the measured cross sections for $^1$H, $^2$H, $^{12}$C and $^{63}$Cu targets at $Q^2$ = 2.15 and 4.0 GeV$^2$ allowing for additional studies of the reaction mechanism. The experimental setup and the analysis of the data are described in detail including systematic studies needed to obtain the results. The results for the nuclear transparency and the differential cross sections as a function of the pion momentum at the different values of $Q^2$ are presented. Global features of the data are discussed and the data are compared with the results of model calculations for the p($e,e'\\pi^{+}$)n reaction from nuclear targets.

  18. Energy loss measurements of {sup 63}Cu, {sup 28}Si and {sup 27}Al heavy ions crossing thin Polyvinylchloride (PVC) foil

    Energy Technology Data Exchange (ETDEWEB)

    Dib, A.; Ammi, H. [Centre de Recherche Nucléaire d’Alger, 2 Bd. Frantz Fanon, B.P. 399, Alger-Gare, Algiers (Algeria); Guesmia, A., E-mail: guesmia@tlabs.ac.za [Departement de physique, Faculté des Sciences, Université Saad Dahlab, B. P. 270, Route de Soumaa, Blida (Algeria); Departement de physique, Faculté des Sciences, Université M’hamed Bougara, Boumerdes (Algeria); iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Msimanga, M. [Department of Physics, Arcadia Campus, Tshwane University of Technology, P. Bag X680, Pretoria (South Africa); Mammeri, S. [Centre de Recherche Nucléaire d’Alger, 2 Bd. Frantz Fanon, B.P. 399, Alger-Gare, Algiers (Algeria); Hedibel, M. [Departement de physique, Faculté des Sciences, Université M’hamed Bougara, Boumerdes (Algeria); Guedioura, B. [Centre de Recherche Nucléaire de Draria, B.P. 43, Sebala-Draria, Algiers (Algeria); Pineda-Vargas, C.A. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Faculty of Health and Wellness Sciences, CPUT, P.O. Box 1906, Bellville 7535 (South Africa)

    2015-11-15

    Experimental stopping data of, {sup 63}Cu, {sup 28}Si and {sup 27}Al heavy ions in thin Polyvinylchloride (H{sub 3}C{sub 2}Cl{sub 1}) foil have been obtained over the 0.045–0.50 MeV/nucleon energy range. The measured energy losses were carried out by Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer. A continuous stopping power data obtained in this work are well fitted by our proposed semi-empirical formula and the results are compared to those calculated by LSS formula or generated by SRIM-2013 and MSTAR predictions. Calculations using our formula agree well with the obtained experimental stopping powers, while the LSS formula underestimates the experimental data in the whole investigated energy range. In this work a simple expression for electronic stopping power of heavy ions at low energy in solid targets is introduced. This formula is based on the Firsov and Lindhard–Sharff stopping power models with a small modification made to the original expression, by incorporating the effective charge of moving ions concept and with exponential fit function.

  19. Synthesis and [superscript 1]H NMR Spectroscopic Elucidation of Five- and Six-Membered D-Ribonolactone Derivatives

    Science.gov (United States)

    Sales, Eric S.; Silveira, Gustavo P.

    2015-01-01

    Lactone-size identification of [subscript D]-ribonolactone derivatives has been debated for four decades due to complex lactone-ring rearrangements and acetal migration. This laboratory experiment for an upper-division undergraduate organic chemistry laboratory course describes a fast and reliable assignment of lactone-size derivatives from…

  20. Synthesis and [superscript 1]H NMR Spectroscopic Elucidation of Five- and Six-Membered D-Ribonolactone Derivatives

    Science.gov (United States)

    Sales, Eric S.; Silveira, Gustavo P.

    2015-01-01

    Lactone-size identification of [subscript D]-ribonolactone derivatives has been debated for four decades due to complex lactone-ring rearrangements and acetal migration. This laboratory experiment for an upper-division undergraduate organic chemistry laboratory course describes a fast and reliable assignment of lactone-size derivatives from…

  1. Photochemical Synthesis and Ligand Exchange Reactions of Ru(CO)[subscript 4] (Eta[superscript 2]-Alkene) Compounds

    Science.gov (United States)

    Cooke, Jason; Berry, David E.; Fawkes, Kelli L.

    2007-01-01

    The photochemical synthesis and subsequent ligand exchange reactions of Ru(CO)[subscript 4] (eta[superscript2]-alkene) compounds has provided a novel experiment for upper-level inorganic chemistry laboratory courses. The experiment is designed to provide a system in which the changing electronic properties of the alkene ligands could be easily…

  2. [[superscript 3]H]-Flunitrazepam-Labeled Benzodiazepine Binding Sites in the Hippocampal Formation in Autism: A Multiple Concentration Autoradiographic Study

    Science.gov (United States)

    Guptill, Jeffrey T.; Booker, Anne B.; Gibbs, Terrell T.; Kemper, Thomas L.; Bauman, Margaret L.; Blatt, Gene J.

    2007-01-01

    Increasing evidence indicates that the GABAergic system in cerebellar and limbic structures is affected in autism. We extended our previous study that found reduced [[superscript 3]H] flunitrazepam-labeled benzodiazepine sites in the autistic hippocampus to determine whether this reduction was due to a decrease in binding site number (B [subscript…

  3. Role of L-Type Ca[superscript 2+] Channel Isoforms in the Extinction of Conditioned Fear

    Science.gov (United States)

    Busquet, Perrine; Hetzenauer, Alfred; Sinnegger-Brauns, Martina J.; Striessnig, Jorg; Singewald, Nicolas

    2008-01-01

    Dihydropyridine (DHP) L-type Ca[superscript 2+] channel (LTCC) antagonists, such as nifedipine, have been reported to impair the extinction of conditioned fear without interfering with its acquisition. Identification of the LTCC isoforms mediating this DHP effect is an essential basis to reveal their role as potential drug targets for the…

  4. Mobility and relaxation determinations of lithium in lithium aluminate ceramics using solid-state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, F.F.; Peterson, E.S. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Stebbins, J.F. [Stanford Univ., CA (United States)] [and others

    1995-02-01

    Lithium aluminate is one of the materials being considered for fusion reactor blankets. When preparing the ceramic, it is important to be able to monitor the microstructures since it is a controlling factor in the rate of tritium release from the blanket. Nuclear magnetic resonance spectroscopy (NMR) has been shown to be a useful tool for the nondestructive analysis of ceramics. Studies detailed in this paper include spectral acquisition, assignment, spin-lattice relaxation time measurements, temperature effects, their correlation to structure, and material purity. The ceramic of interest was lithium aluminate, LiAl{sub 5}O{sub 8}. This material was studied by observation of the NMR active nuclei {sup 6}Li, {sup 7}Li, and {sup 27}Al. For these nuclei, spin-lattice relaxation times (T{sub 1}) were measured and were found to vary considerably, correlating to the presence of paramagnetic impurities within the crystalline lattice. Previous research has shown that the coordination about the aluminum nucleus can be determined using {sup 27}Al NMR spectroscopy. Aluminum-27 NMR spectroscopy was successfully applied, and it provided valuable insight into composition of the ceramic. 20 refs., 4 figs., 3 tabs.

  5. The Effects of Temperature, Viscosity, and Molecular Size on the Aluminum-27 QCT NMR of Transferrins

    Science.gov (United States)

    Aramini, James M.; Vogel, Hans J.

    1996-02-01

    A number of reports in recent years have demonstrated the feasibility of detecting quadrupolar metal ions bound tightly to rather large proteins via the quadrupolar central transition (QCT) NMR approach. In this article, an in-depth investigation of several interesting properties of transferrin-bound27Al NMR signals, namely, their dependence on temperature, viscosity, and molecular size is presented. It is shown that (1) decreasing temperature and (2) increasing viscosity by adding reagents such as glycerol and ethylene glycol perturb only the linewidths of transferrin-bound27Al signals, and, in fact, produce a decrease in signal linewidth. These effects are in accord with quadrupolar relaxation theory, which predicts that the linewidth of the central transition of a half-integer quadrupolar nucleus should decrease with increasing correlation time of the protein under nonextreme narrowing conditions. Furthermore, it is demonstrated that these trends, which are completely opposite to those generally observed in NMR spectroscopy, can be exploited to monitor ovotransferrin half-molecule reassociation reactions. In combination with the peculiar properties of transferrin-bound quadrupolar nuclei reported in the literature to date, the phenomena described here provide the basis for understanding the conditions and experimental parameters which may facilitate the application of the QCT NMR technique to the study of other quadrupolar nuclei and proteins.

  6. Validation of quantitative {sup 1}H NMR method for the analysis of pharmaceutical formulations; Validacao de metodo quantitativo por RMN de {sup 1}H para analises de formulacoes farmaceuticas

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara da S. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Colnago, Luiz Alberto, E-mail: luiz.colnago@embrapa.br [Embrapa Instrumentacao, Sao Carlos, SP (Brazil)

    2013-09-01

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

  7. NMR of lignins

    Science.gov (United States)

    John Ralph; Larry L. Landucci

    2010-01-01

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

  8. A Comparative Study of Different Amorphous and Paracrystalline Silica by NMR and SEM/EDS

    Institute of Scientific and Technical Information of China (English)

    JIA Yuan; WANG Baomin; ZHANG Tingting

    2015-01-01

    This work aimed to research the structure models of amorphous materials. Five amorphous and paracrystalline samples (natural or artiifcial) were investigated via29Si/27Al nuclear magnetic resonance (NMR) and field emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS). The results of NMR showed the resonances of different specimens:-93.2 ppm,-101.8 ppm,-111.8 ppm for natural pozzolana opal shale (POS). These peaks were assigned to the Q2(2OH), Q3(OH)/Q4(1Al) and Q4 respectively. The results of27Al MAS NMR indicated that Al substituted for Si site in tetrahedral existing in the POS, while the Al/Si atomic ratio in opal was low (around 0.04). For the alkali-silicate-hydrate gel, there were at least three resolved signals assigned to Q0 and Q1, respectively. For the fused silica glass powder, there were the primary signals centered about at the range from-107 to-137 ppm, which were assigned to Q4 units. In addition, the peaks at around-98 and-108 ppm were corresponding to Q3(1OH) and Q4 units existing in aerogel silica structure.

  9. Infrared and MAS NMR Spectroscopic Studies of Al18B4O33

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The IR spectrum and 11B and 27Al MAS NMR spectra of Al18B4O33 are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms. TheIR spectrum shows that the strong vibrations of the BO3 groups are present in the 1 500~1 200em-1 region, and very weak bands of BO4 units are present in the region from 1 000 to 1 100cm-1. 11B MAS NMR spectrum indicates that the strong signal for BO3 units appears in the region from δ +5 to δ +20, and the very weak signal for BO4 units is at about δ-1, while 27AlMAS NMR spectrum shows five peaks at about δ +62, +42. 1, +14,-4.7 and-6.4, originating from AlO4, AlO4, A1O5, AlO6 and AlO6, respectively. These results reveal that there areminor BO4 units in Al18B4O33, indicating that a small amount of B atoms substitute for Al atomsin the 4-fold coordination.

  10. Observation of Distinct Surface AlIV Sites and Phosphonate Binding Modes in Gamma-Alumina and Concrete by High-Field 27Al and 31P MAS NMR

    Science.gov (United States)

    2009-01-01

    indeed the case for concrete, especially for species such as 6 and 7 which can typically only be dissolved (extracted) by protic media at acidic pH .3...Munavalli, S.; Carnes , C. L.; Kapoor, P. N.; Klabunde, K. J. J. Am. Chem. Soc. 2001, 123, 1636–1644. (4) Wagner, G. W.; Procell, L. R.; Munavalli, S. J

  11. A multinuclear static NMR study of geopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  12. The Flexible Mind Is Associated with the Catechol-O-Methyltransferase (COMT) Val[superscript 158]Met Polymorphism: Evidence for a Role of Dopamine in the Control of Task-Switching

    Science.gov (United States)

    Colzato, Lorenza S.; Waszak, Florian; Nieuwenhuis, Sander; Posthuma, Danielle; Hommel, Bernhard

    2010-01-01

    Genetic variability related to the catechol-O-methyltransferase (COMT) gene Val[superscript 128]Met polymorphism) has received increasing attention as a possible modulator of cognitive control functions. Recent evidence suggests that the Val[superscript 128]Met genotype may differentially affect cognitive stability and flexibility, in such a way…

  13. 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.

  14. Extra-framework aluminium species in hydrated faujasite zeolite as investigated by two-dimensional solid-state NMR spectroscopy and theoretical calculations.

    Science.gov (United States)

    Li, Shenhui; Zheng, Anmin; Su, Yongchao; Fang, Hanjun; Shen, Wanling; Yu, Zhiwu; Chen, Lei; Deng, Feng

    2010-04-21

    Extra-framework aluminium (EFAL) species in hydrated dealuminated HY zeolite were thoroughly investigated by various two-dimensional solid-state NMR techniques as well as density functional theoretical calculations. (27)Al MQ MAS NMR experiments demonstrated that five-coordinated and four-coordinated extra-framework aluminium subsequently disappeared with the increase of water loading, and the quadrupole interaction of each aluminium species decreased gradually during the hydration process. (1)H double quantum MAS NMR revealed that the EFAL species in the hydrated zeolite consisted of three components: a hydroxyl AlOH group, and two types of water molecule (rigid and mobile water). (1)H-(27)Al LG-CP HETCOR experiments indicated that both the extra-framework and the framework Al atoms were in close proximity to the rigid water in the fully rehydrated zeolite. The experimental results were further confirmed by DFT theoretical calculations. Moreover, theoretical calculation results further demonstrated that the EFAL species in the hydrated zeolite consisted of the three components and the calculated (1)H NMR chemical shift for each component agreed well with our NMR observations. It is the rigid water that connects the extra-framework aluminium with the four-coordinated framework aluminium through strong hydrogen bonds.

  15. Solid-state NMR studies of Al-doped and Al{sub 2}O{sub 3}-coated LiCoO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngil; Kim, Dongmin; Lee, Hyeyeoun [Dongbu Advanced Research Inst., Daejeon (Korea). Chemical Analysis Team; Woo, Ae Ja [Ewha Womans Univ., Seoul (Korea); Han, Kyoo Seung [Chungnam National Univ., Daejeon (Korea). Dept. of Fine Chemicals Engineering and Chemistry; Ryu, D. [Electronics and Telecommunications Research Inst., Daejeon (Korea); Sohn, Daewon [Hanyang Univ., Seoul (Korea). Dept. of Chemistry

    2004-11-30

    As a cathode material for commercial lithium rechargeable battery, Al-doped and Al{sub 2}O{sub 3}-coated LiCoO{sub 2} were structurally characterized and compared by using solid-state {sup 7}Li and {sup 27}Al magic angle spinning (MAS) NMR. The structural states of lithium and aluminum in those samples were successfully identified by calculation of NMR spectra. {sup 7}Li MAS NMR spectra of samples had shown similar features having more than three lithium sites, which were determined as quadrupole coupling constant with the same asymmetric parameter ({eta} = 0.1); C{sub Q} = 1.10 MHz for octahedral site, and C{sub Q} 2.97 MHz and C{sub Q} = 3.83 MHz for shoulders. {sup 27}Al MAS NMR spectra of samples, however, showed significant difference in two observed aluminum sites. In the simulation of NMR spectrum for Al{sub 2}O{sub 3}-coated LiCoO{sub 2}, the values of C{sub Q} and {eta} were obtained; 4.45 MHz and {eta} = 0.86 for tetrahedral site and 4.31 MHz and {eta} = 0.81 for octahedral.

  16. High-pressure low-temperature locknut cell for both EPR and NMR studies to 10 kilobars and 77 K

    Science.gov (United States)

    Sinha, Shantanu; Srinivasan, R.

    1983-11-01

    A locked high-pressure cell with working pressure range up to 10 kbars suitable for low-temperature studies to 77 K has been described. It can be used for both EPR and NMR studies of single crystals (and other solid samples). The high-pressure seal and all other aspects of the cell remain the same for either application. Only a change of the bottom plug is required for a switch from a nuclear-magnetic-resonance (NMR) to an electron-paramagnetic-resonance (EPR) experiment. Details of the procedure for the calibration of pressure inside the cell at various temperatures are discussed. The performance of the cell in EPR (Cr3+ion) and NMR (27Al nucleus) studies is reported.

  17. NMR logging apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, David O; Turner, Peter

    2014-05-27

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

  18. NMR logging apparatus

    Science.gov (United States)

    Walsh, David O; Turner, Peter

    2014-05-27

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

  19. NMR studies of metalloproteins.

    Science.gov (United States)

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has long been used as an invaluable tool for structure and dynamic studies of macromolecules. Here we focus on the application of NMR spectroscopy in characterization of metalloproteins, including structural studies and identification of metal coordination spheres by hetero-/homo-nuclear metal NMR spectroscopy. Paramagnetic NMR as well as (13)C directly detected protonless NMR spectroscopy will also be addressed for application to paramagnetic metalloproteins. Moreover, these techniques offer great potential for studies of other non-metal binding macromolecules.

  20. NMR sensor for onboard ship detection of catalytic fines in marine fuel oils.

    Science.gov (United States)

    Sørensen, Morten K; Vinding, Mads S; Bakharev, Oleg N; Nesgaard, Tomas; Jensen, Ole; Nielsen, Niels Chr

    2014-08-01

    A mobile, low-field nuclear magnetic resonance (NMR) sensor for onboard, inline detection of catalytic fines in fuel oil in the shipping industry is presented as an alternative to onshore laboratory measurements. Catalytic fines (called cat fines) are aluminosilicate zeolite catalysts utilized in the oil cracking process at refineries. When present in fuel oil, cat fines cause abrasive wear of engine parts and may ultimately lead to engine breakdown with large economical consequences, thereby motivating methods for inline measurements. Here, we report on a robust, mobile, and low-cost (27)Al NMR sensor for continuous online measurement of the level of catalytic fines in fuel oil onboard ships. The sensor enables accurate measurements of aluminum (catalytic fines) in ppm concentrations in good agreement with commercial laboratory reference measurements.

  1. Investigating lanthanide dopant distributions in Yttrium Aluminum Garnet (YAG) using solid state paramagnetic NMR.

    Science.gov (United States)

    McCarty, Ryan J; Stebbins, Jonathan F

    2016-10-01

    This paper demonstrates the approach of using paramagnetic effects observed in NMR spectra to investigate the distribution of lanthanide dopant cations in YAG (yttrium aluminum garnet, Y3Al5O12) optical materials, as a complimentary technique to optical spectroscopy and other standard methods of characterization. We investigate the effects of Ce(3+), Nd(3+), Yb(3+), Tm(3+), and Tm(3+)-Cr(3+) on (27)Al and (89)Y NMR spectra. We note shifted resonances for both AlO4 and AlO6 sites. In some cases, multiple shifted peaks are observable, and some of these can be empirically assigned to dopant cations in known configurations to the observed nuclides. In many cases, AlO6 peaks shifted by more than one magnetic neighbor can be detected. In general, we observe that the measured intensities of shifted resonances, when spinning sidebands are included, are consistent with predictions from models with dopant cations that are randomly distributed throughout the lattice. In at least one set of (27)Al spectra, we identify two sub-peaks possibly resulting from two paramagnetic cations with magnetically coupled spin states neighboring the observed nucleus. We identify systematic changes in the spectra related to known parameters describing the magnetic effects of lanthanide cations, such as larger shift distances when the expectation value of electron spins is greater. We lastly comment on the promise of this technique in future analyses of laser and other crystalline oxide materials. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. UC Merced NMR Instrumentation Acquisition

    Science.gov (United States)

    2015-06-18

    UC Merced NMR Instrumentation Acquisition For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500 MHz NMR ...UC Merced NMR Instrumentation Acquisition Report Title For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500...MHz NMR have been delivered, installed, and incorporated into research and two lab courses. While no results from these instruments have been

  3. Heavy-ion fusion cross sections of weakly bound {sup 9}Be on {sup 27}Al, {sup 64}Zn and tightly bound {sup 16}O on {sup 64}Zn target using Coulomb and proximity potential

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K.P., E-mail: drkpsanthosh@gmail.com; Bobby Jose, V.

    2014-02-15

    The total fusion cross sections for the fusion of weakly bound {sup 9}Be on {sup 27}Al and {sup 64}Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus {sup 16}O on {sup 64}Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems {sup 9}Be+{sup 27}Al, {sup 9}Be+{sup 64}Zn and {sup 16}O+{sup 64}Zn have also been described.

  4. Heavy-ion fusion cross sections of weakly bound $^{9}$Be on $^{27}$Al, $^{64}$Zn and tightly bound $^{16}$O on $^{64}$Zn target using Coulomb and proximity potential

    CERN Document Server

    Santhosh, K P

    2013-01-01

    The total fusion cross sections for the fusion of weakly bound $^{9}$Be on $^{27}$Al and $^{64}$Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus $^{16}$O on $^{64}$Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems $^{9}$Be + $^{27}$Al, $^{9}$Be+ $^{64}$Zn and $^{16}$O + $^{64}$Zn have also been d...

  5. Benford distributions in NMR

    CERN Document Server

    Bhole, Gaurav; Mahesh, T S

    2014-01-01

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

  6. Binary Logistic Regression Analysis for Detecting Differential Item Functioning: Effectiveness of R[superscript 2] and Delta Log Odds Ratio Effect Size Measures

    Science.gov (United States)

    Hidalgo, Mª Dolores; Gómez-Benito, Juana; Zumbo, Bruno D.

    2014-01-01

    The authors analyze the effectiveness of the R[superscript 2] and delta log odds ratio effect size measures when using logistic regression analysis to detect differential item functioning (DIF) in dichotomous items. A simulation study was carried out, and the Type I error rate and power estimates under conditions in which only statistical testing…

  7. Binary Logistic Regression Analysis for Detecting Differential Item Functioning: Effectiveness of R[superscript 2] and Delta Log Odds Ratio Effect Size Measures

    Science.gov (United States)

    Hidalgo, Mª Dolores; Gómez-Benito, Juana; Zumbo, Bruno D.

    2014-01-01

    The authors analyze the effectiveness of the R[superscript 2] and delta log odds ratio effect size measures when using logistic regression analysis to detect differential item functioning (DIF) in dichotomous items. A simulation study was carried out, and the Type I error rate and power estimates under conditions in which only statistical testing…

  8. The Relationship between Post Reach Exit Exam (E[superscript 2]) Failure Remediation and NCLEX-RN Success of Graduates of Baccalaureate Nursing Programs

    Science.gov (United States)

    Allen, Patricia Gale

    2009-01-01

    An ex post facto study was conducted to determine whether any relationship exists between remediation post Reach Exit Exam (E[superscript 2]) failure and NCLEX-RN success of graduates of baccalaureate nursing programs. Data was gathered from responses to the seventh annual validity study (V7S) offered to deans and directors of nursing programs by…

  9. Lower "N"-Acetyl-Aspartate Levels in Prefrontal Cortices in Pediatric Bipolar Disorder: A (Superscript 1]H Magnetic Resonance Spectroscopy Study

    Science.gov (United States)

    Caetano, Sheila C.; Olvera, Rene L.; Hatch, John P.; Sanches, Marsal; Chen, Hua Hsuan; Nicoletti, Mark; Stanley, Jeffrey A.; Fonseca, Manoela; Hunter, Kristina; Lafer, Beny; Pliszka, Steven R.; Soares, Jair C.

    2011-01-01

    Objective: The few studies applying single-voxel [superscript 1]H spectroscopy in children and adolescents with bipolar disorder (BD) have reported low "N"-acetyl-aspartate (NAA) levels in the dorsolateral prefrontal cortex (DLPFC), and high myo-inositol/phosphocreatine plus creatine (PCr+Cr) ratios in the anterior cingulate. The aim of this study…

  10. Students' Understanding of Limiting Behavior at a Point for Functions from [Set of Real Numbers][superscript 2] to [Set of Real Numbers

    Science.gov (United States)

    Mamona-Downs, Joanna K.; Megalou, Foteini J.

    2013-01-01

    The aim of this paper is to examine students' understanding of the limiting behavior of a function from [set of real numbers][superscript 2] to [set of real numbers] at a point "P." This understanding depends on which definition is used for a limit. Several definitions are considered; two of these concern the notion of a neighborhood of "P", while…

  11. Alterations in CNS Activity Induced by Botulinum Toxin Treatment in Spasmodic Dysphonia: An H[subscript 2][superscript 15]O PET Study

    Science.gov (United States)

    Ali, S. Omar; Thomassen, Michael; Schulz, Geralyn M.; Hosey, Lara A.; Varga, Mary; Ludlow, Christy L.; Braun, Allen R.

    2006-01-01

    Speech-related changes in regional cerebral blood flow (rCBF) were measured using H[subscript 2][superscript 15]O positron-emission tomography in 9 adults with adductor spasmodic dysphonia (ADSD) before and after botulinum toxin (BTX) injection and 10 age- and gender-matched volunteers without neurological disorders. Scans were acquired at rest…

  12. The Influence of Tier One of RtI[superscript 2] and Instructional Coaching on Teacher Instruction and Student/ELL Learning: A Multiple Case Study

    Science.gov (United States)

    Valadez, Frances E.

    2012-01-01

    The purpose of this case study was to demonstrate the influence of Tier 1 of Response to Intervention and Instruction (RtI[superscript 2]) and instructional coaching on teachers' instruction and on students' and English Language Learners' (ELL) learning. Research was conducted in one large urban elementary school. The unit of study…

  13. What Does f[subscript xx]f[subscript yy] - f[superscript 2][subscript xy] Greater than 0 "Really" Mean?

    Science.gov (United States)

    McCartin, Brian J.

    2008-01-01

    This note presents geometric and physical interpretations of the sufficient condition for a critical point to be a strict relative extremum: f[subscript xx]f[subscript yy] - f[superscript 2][subscript xy] greater than 0. The role of the double derivative f[subscript xy] in this inequality will be highlighted in these interpretations. (Contains 14…

  14. Catechol-O-Methyltransferase "Val[superscript 158]Met" Genotype, Parenting Practices and Adolescent Alcohol Use: Testing the Differential Susceptibility Hypothesis

    Science.gov (United States)

    Laucht, Manfred; Blomeyer, Dorothea; Buchmann, Arlette F.; Treutlein, Jens; Schmidt, Martin H.; Esser, Gunter; Jennen-Steinmetz, Christine; Rietschel, Marcella; Zimmermann, Ulrich S.; Banaschewski, Tobias

    2012-01-01

    Background: Recently, first evidence has been reported for a gene-parenting interaction (G x E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase ("COMT") "Val[superscript 158]Met" polymorphism as a genetic susceptibility factor. Moreover, the current study…

  15. What Does f[subscript xx]f[subscript yy] - f[superscript 2][subscript xy] Greater than 0 "Really" Mean?

    Science.gov (United States)

    McCartin, Brian J.

    2008-01-01

    This note presents geometric and physical interpretations of the sufficient condition for a critical point to be a strict relative extremum: f[subscript xx]f[subscript yy] - f[superscript 2][subscript xy] greater than 0. The role of the double derivative f[subscript xy] in this inequality will be highlighted in these interpretations. (Contains 14…

  16. Determining the Transference Number of H[superscript +](aq) by a Modified Moving Boundary Method: A Directed Study for the Undergraduate Physical Chemistry Laboratory

    Science.gov (United States)

    Dabke, Rajeev B.; Gebeyehu, Zewdu; Padelford, Jonathan

    2012-01-01

    A directed study for the undergraduate physical chemistry laboratory for determining the transference number of H[superscript +](aq) using a modified moving boundary method is presented. The laboratory study combines Faraday's laws of electrolysis with mole ratios and the perfect gas equation. The volume of hydrogen gas produced at the cathode is…

  17. PR[superscript 2]EPS: Preparation, Recruitment, Retention and Excellence in the Physical Sciences, Including Engineering. A Report on the 2004, 2005 and 2006 Science Summer Camps

    Science.gov (United States)

    Bachman, Nancy J.; Bischoff, Paul J.; Gallagher, Hugh; Labroo, Sunil; Schaumloffel, John C.

    2008-01-01

    Now in its fourth year, PR[superscript 2]EPS is a National Science Foundation funded initiative designed to recruit high school students to attend college majoring in the physical sciences, including engineering and secondary science education, and to help ensure their retention within the program until graduation. A central feature of the…

  18. Gray Matter Volume in Adolescent Anxiety: An Impact of the Brain-Derived Neurotrophic Factor Val[superscript 66]Met Polymorphism?

    Science.gov (United States)

    Mueller, Sven C.; Aouidad, Aveline; Gorodetsky, Elena; Goldman, David; Pine, Daniel S.; Ernst, Monique

    2013-01-01

    Objective: Minimal research links anxiety disorders in adolescents to regional gray matter volume (GMV) abnormalities and their modulation by genetic factors. Prior research suggests that a brain-derived neurotrophic factor (BNDF) Val[superscript 66]Met polymorphism may modulate such brain morphometry profiles. Method: Using voxel-based…

  19. Gray Matter Volume in Adolescent Anxiety: An Impact of the Brain-Derived Neurotrophic Factor Val[superscript 66]Met Polymorphism?

    Science.gov (United States)

    Mueller, Sven C.; Aouidad, Aveline; Gorodetsky, Elena; Goldman, David; Pine, Daniel S.; Ernst, Monique

    2013-01-01

    Objective: Minimal research links anxiety disorders in adolescents to regional gray matter volume (GMV) abnormalities and their modulation by genetic factors. Prior research suggests that a brain-derived neurotrophic factor (BNDF) Val[superscript 66]Met polymorphism may modulate such brain morphometry profiles. Method: Using voxel-based…

  20. Lower "N"-Acetyl-Aspartate Levels in Prefrontal Cortices in Pediatric Bipolar Disorder: A (Superscript 1]H Magnetic Resonance Spectroscopy Study

    Science.gov (United States)

    Caetano, Sheila C.; Olvera, Rene L.; Hatch, John P.; Sanches, Marsal; Chen, Hua Hsuan; Nicoletti, Mark; Stanley, Jeffrey A.; Fonseca, Manoela; Hunter, Kristina; Lafer, Beny; Pliszka, Steven R.; Soares, Jair C.

    2011-01-01

    Objective: The few studies applying single-voxel [superscript 1]H spectroscopy in children and adolescents with bipolar disorder (BD) have reported low "N"-acetyl-aspartate (NAA) levels in the dorsolateral prefrontal cortex (DLPFC), and high myo-inositol/phosphocreatine plus creatine (PCr+Cr) ratios in the anterior cingulate. The aim of this study…

  1. Utilizing Organizational Culture to Predict Responses to Planned Change in a Public School: A Test of the OC[superscript 3] Model

    Science.gov (United States)

    Sandberg, Eric Christian

    2012-01-01

    The primary purpose of this research was to test the capability of the Organizational Change in Cultural Context (OC[superscript 3]) Model (Latta, 2009, 2011) to predict responses to change. According to Latta, predictions of resistance to or facilitation of change can be predicted by utilizing organizational culture and its alignment with the…

  2. Optical and scintillation properties of Ce-doped (Gd{sub 2}Y{sub 1})Ga{sub 2.7}Al{sub 2.3}O{sub 12} single crystal grown by Czochralski method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Wu, Yuntao; Ding, Dongzhou; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Ren, Guohao, E-mail: rgh@mail.sic.ac.cn

    2016-06-01

    Multicomponent garnets, due to their excellent light yield and energy resolution, become one of the most promising scintillators used for homeland security and nuclear non-proliferation applications. This work focuses on the optimization of Ce-doped (Gd,Y){sub 3}(Ga,Al){sub 5}O{sub 12} scintillators using a combination strategy of pre-screening and scale-up. Ce-doped Gd{sub x}Y{sub 1−x}Ga{sub y}Al{sub 5−y}O{sub 12} (x=1, 2 and y=2, 2.2, 2.5, 2.7, 3) polycrystalline powders were prepared by high-temperature solid state reaction method. The desired garnet phase in all the samples was confirmed using X-ray diffraction measurement. By comparing the radioluminescence intensity, the highest scintillation efficiency was achieved at a component of Gd{sub 2}Y{sub 1}Ga{sub 2.7}Al{sub 2.3}O{sub 12}:Ce powders. A (Gd{sub 2}Y{sub 1})Ga{sub 2.7}Al{sub 2.3}O{sub 12} doped with 1% Ce single crystal with dimensions of Ø35×40 mm was grown by Czochralski method using a <111> oriented seed. Luminescence and scintillation properties were measured. An optical transmittance of 84% was achieved in the concerned wavelength from 500 to 800 nm. Its 5d–4f emission of Ce{sup 3+} is at 530 nm. The light yield of a Ce1%: Gd{sub 2}Y{sub 1}Ga{sub 2.7}Al{sub 2.3}O{sub 12} single crystal slab at a size of 5×5×1 mm{sup 3} can reach about 65,000±3000 Ph/MeV along with two decay components of 94 and 615 ns under {sup 137}Cs source irradiation.

  3. SQUID detected NMR and NQR. Superconducting Quantum Interference Device.

    Science.gov (United States)

    Augustine, M P; TonThat, D M; Clarke, J

    1998-03-01

    The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 muphi0 Hz(-1/2) at liquid helium temperatures. Here phi0 = h/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned input circuit the SQUID measures the flux, rather than the rate of change of flux, and thus retains its high sensitivity down to arbitrarily low frequencies. This feature is exploited in a cw spectrometer that monitors the change in the static magnetization of a sample induced by radio frequency irradiation. Examples of this technique are the detection of NQR in 27Al in sapphire and 11B in boron nitride, and a level crossing technique to enhance the signal of 14N in peptides. Research is now focused on a SQUID-based spectrometer for pulsed NQR and NMR, which has a bandwidth of 0-5 MHz. This spectrometer is used with spin-echo techniques to measure the NQR longitudinal and transverse relaxation times of 14N in NH4ClO4, 63+/-6 ms and 22+/-2 ms, respectively. With the aid of two-frequency pulses to excite the 359 kHz and 714 kHz resonances in ruby simultaneously, it is possible to obtain a two-dimensional NQR spectrum. As a third example, the pulsed spectrometer is used to study NMR spectrum of 129Xe after polariza-tion with optically pumped Rb. The NMR line can be detected at frequencies as low as 200 Hz. At fields below about 2 mT the longitudinal relaxation time saturates at about 2000 s. Two recent experiments in other laboratories have extended these pulsed NMR techniques to higher temperatures and smaller samples. In the first, images were obtained of mineral oil floating on water at room temperature. In the second, a SQUID configured as a thin film gradiometer was used to detect NMR in a 50 microm particle of 195Pt at 6 mT and 4.2 K.

  4. MAS-NMR investigations of the crystallization behaviour of lithium aluminum silicate (LAS) glasses containing P 2O 5 and TiO 2 nucleants

    Science.gov (United States)

    Ananthanarayanan, A.; Kothiyal, G. P.; Montagne, L.; Revel, B.

    2010-06-01

    Lithium aluminum silicate (LAS) glass of composition (mol%) 20.4Li 2O-4.0Al 2O 3-68.6SiO 2-3.0K 2O-2.6B 2O 3-0.5P 2O 5-0.9TiO 2 was prepared by melt quenching. The glass was then nucleated and crystallized based on differential thermal analysis (DTA) data and was characterized by 29Si, 31P, 11B and 27Al MAS-NMR. XRD and 29Si NMR showed that lithium metasilicate (Li 2SiO 3) is the first phase to c form followed by cristobalite (SiO 2) and lithium disilicate (Li 2Si 2O 5). 29Si MAS-NMR revealed a change in the network structure already for the glasses nucleated at 550 °C. Since crystalline Li 3PO 4, as observed by 31P MAS-NMR, forms concurrently with the silicate phases, we conclude that crystalline Li 3PO 4 does not act as a nucleating agent for lithium silicate phases. Moreover, 31P NMR indicates the formation of M-PO 4 ( M=B, Al or Ti) complexes. The presence of BO 3 and BO 4 structural units in all the glass/glass-ceramic samples is revealed through 11B MAS-NMR. B remains in the residual glass and the crystallization of silicate phases causes a reduction in the number of alkali ions available for charge compensation. As a result, the number of trigonally coordinated B (BO 3) increases at the expense of tetrahedrally coordinated B (BO 4). The 27Al MAS-NMR spectra indicate the presence of tetrahedrally coordinated Al species, which are only slightly perturbed by the crystallization.

  5. Fusion near and below the barrier for the systems /sup 32,34/S+/sup 24,25,26/Mg and /sup 32/S+/sup 27/Al

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, G.M.; Braun-Munzinger, P.; Karp, J.S.; Freifelder, R.H.; Renner, T.R.; Wilschut, H.W.

    1983-08-01

    Excitation functions are reported for total fusion near and below the Coulomb barrier of the systems /sup 32,34/S+/sup 24,25,26/Mg and /sup 27/Al. The data cannot be reproduced by one-dimensional barrier penetration calculations. The enhancement of the cross sections at low energies is compared to predictions of models taking into acount the static deformation or zero point vibration of the reaction partners. Calculations including zero point motion do not reproduce the observed variations of the measured cross sections with respect to the neutron number of target and projectile. Reasonable agreement is obtained when calculating fusion between statically deformed nuclei. Finally, the fusion process is described in a quantum mechanical coupled channels model, indicating the importance of dynamical effect on sub-barrier fusion.

  6. Evidence of a two-source emission fo light charged particles in coincidence with pions produced in sup 16 O+ sup 27 Al collisions at 94 MeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Barbera, R.; Badala, A.; Adorno, A.; Bonasera, A.; Di Toro, M.; Palmeri, A.; Pappalardo, G.S. (Istituto Nazionale di Fisica Nucleare, Catania (Italy)); Bizard, G.; Bougault, R.; Durand, D.; Genoux-Lubain, A.; Laville, J.L.; Lefebvres, F.; Patry, J.P. (Caen Univ., 14 (France). Lab. de Physique Corpusculaire); Jin, G.M. (Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)); Rosato, E. (Naples Univ. (Italy). Dipt. di Scienze Fisiche Istituto Nazionale di Fisica Nucleare, Naples (Italy))

    1990-11-26

    H and He ions have been detected in coincidence with charged pions in the reaction induced by {sup 16}O on {sup 27}Al target at 94 MeV/u incident energy. We analyse velocity spectra and cross sections of He ions emitted in the angular range 4deg-150deg in coincidence with charged pions detected at 90deg. A two-source emission mechanism of the helium particles and a pion statistical production from an equilibrated participant zone is stressed. The absolute yields at different angles are compared with results of a theoretical model for medium energy heavy-ion reactions in the framework of a participant-spectator picture. (orig.).

  7. Teaching NMR Using Online Textbooks

    Directory of Open Access Journals (Sweden)

    Joseph P. Hornak

    1999-12-01

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

  8. Investigation of Ti-doped NaAlH4 by solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Majzoub, E; Herberg, J

    2003-11-24

    In recent years, the development of Ti-doped NaAlH{sub 4} as a hydrogen storage material has gained attention because of its large weight percentage of hydrogen ({approx}5%) compared to traditional interstitial hydrides. The addition of transition-metal dopants, in the form of Ti-halides, such as TiCl{sub 3}, dramatically improves the kinetics of the absorption and desorption of hydrogen from NaAlH{sub 4}. However, the role that Ti plays in enhancing the absorption and desorption of H{sub 2} is still unknown. In the present study, {sup 27}Al, {sup 23}Na, and {sup 1}H MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) has been performed to understand the titanium speciation in Ti-doped NaAlH{sub 4}. All experiments were performed on a sample of crushed single crystals exposed to Ti during growth, a sample of solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, a reacted sample of solvent-mixed TiCl{sub 3} + {sup 3}NaAlH{sub 4} with THF, and a reacted sample of ball-milled TiCl3 + 3NaAlH{sub 4}. The {sup 27}Al MAS NMR has shown differences in compound formation between solvent-mixed TiCl{sub 3} + 3NaAlH{sub 4} with THF and the mechanically ball-milled TiCl{sub 3} + 3NaAlH{sub 4}. {sup 27}Al MAS NMR of the mechanically ball-milled mixture of fully-reacted TiCl{sub 3} + 3NaAlH{sub 4} showed spectral signatures of TiAl{sub 3} while, the solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, which is totally reacted, does not show the presences of TiAl{sub 3}, but shows the existence of Al{sub 2}O{sub 3}.

  9. Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs.

    Science.gov (United States)

    Edén, Mattias

    2010-05-01

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental (23)Na and (27)Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl(2)O(5)), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations.

  10. NMR, Water and Plants

    NARCIS (Netherlands)

    As, van H.

    1982-01-01

    This Thesis describes the application of a non-destructive pulsed proton NMR method mainly to measure water transport in the xylem vessels of plant stems and in some model systems. The results are equally well applicable to liquid flow in other biological objects than plants, e.g. flow of blood and

  11. Single-sided NMR

    CERN Document Server

    Casanova, Federico; Blümich, Bernhard

    2011-01-01

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

  12. Autonomous driving in NMR.

    Science.gov (United States)

    Perez, Manuel

    2017-01-01

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

  13. 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

  14. NMR charaterization of the pseudogap at the Fermi level in Quasicrystals

    Science.gov (United States)

    Tang, X.-P.; Wonnell, S. K.; Hill, E. A.; Wu, Y.; Poon, S. J.

    1996-11-01

    The electronic properties of quasicrystals and their crystalline approximants have been studied by ^27Al nuclear magnetic resonance. An anomalous temperature dependence of the spin-lattice relaxation rate (T_1-1), T_1-1 ~ T^2, was observed in a broad temperature range in i-AlCuFe, R-AlCuFe, i-AlCuRu, i-AlPdRe, and α-AlMnSi. This temperature dependence can be explained by the presence of a pseudogap described by g(E) ~ |E-E_F|^1/2. This type of density-of-state was predicted by a recent theoretical calculation(C. Janot et. al., Phys. Rev. Lett. 72, 1674(1994)) and also was indicated by a recent photonemission measurement (X. Wu et. al., Phys. Rev. Lett. 75, 4540(1995)) in i-AlPdMn. Our NMR results gave the first experimental evidence that this special electronic density-of-state is a common feature in quasicrystals. For all these samples, reasonable width of the pseudogap has been obtained from the temperature dependence of the spin-lattice relaxation rate. A weak temperature dependence of the Knight shift K ~ T^1/2, as a result of g(E) ~ |E-E_F|^1/2 is also consistent with our ^27Al measurements.

  15. NMR for chemists and biologists

    CERN Document Server

    Carbajo, Rodrigo J

    2013-01-01

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

  16. NMR magnet technology at MIT

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.E.C.; Bobrov, E.S.; Iwasa, Y.; Punchard, W.F.B.; Wrenn, J.; Zhukovsky, A. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab.)

    1992-01-01

    The design and construction of high field superconducting NMR magnets has much in common with other types of adiabatic superconducting magnets. However, two issues have a particular relevance to NMR magnets. They are field drift and homogeneity. In this paper the control of these factors in the particular context of high field NMR spectrometer magnets is examined.

  17. 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.

  18. NMR studies of metalloproteins

    OpenAIRE

    Li, H; H. Sun

    2011-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has...

  19. Formation of an Oxidant-Sensible Pd(II) Coordination Compound and Its [superscript 1]H NMR Specific Characterization: A Preparative and Analytical Challenge in Current Coordination Chemistry

    Science.gov (United States)

    Abraham, Maria L.; Oppel, Iris M.

    2014-01-01

    A three-part experiment that leads to the synthesis of palladium(II) complex starting from a C[subscript 3]-symmetric triaminoguanidinium-based ligand is presented. In the first part, the preparation of tris-benzylidenetriaminoguanidinium chloride ([H[subscript 6]Br[subscript 3]L]Cl) by an acidic catalyzed 3-fold imine formation reaction of…

  20. Effect of thermal annealing on scintillation properties of Ce:Gd{sub 2}Y{sub 1}Ga{sub 2.7}Al{sub 2.3}O{sub 12} under different atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Ding, Dongzhou; Wu, Yuntao; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Wang, Qingqing; Ye, Le; Ren, Guohao [Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai (China)

    2017-05-15

    Cerium-doped 1% Ce:Gd{sub 2}Y{sub 1}Ga{sub 2.7}Al{sub 2.3}O{sub 12}(GYGAG) single crystal samples grown via Czochralski method were annealed under air, O{sub 2} and N{sub 2} atmospheres from 350 to 1400 C. The X-ray excited luminescence spectra, energy spectra and UV as well as thermally stimulated luminescence (TSL) spectra were performed comparatively on ''as-grown'' and thermally annealed samples. It was found that the luminescence efficiency after annealing in air and O{sub 2} was significantly enhanced compared to the non-annealed samples and this phenomenon was suggested to be caused by the existence of some oxygen vacancies in the Ce:GYGAG crystals. And the oxygen vacancies in the as-grown GYGAG crystals can be effectively eliminated by means of annealing in O{sub 2} containing atmosphere without changing the luminescence mechanism. From the TSL curves before and after annealing, three traps within 77-650 K were found to be related to oxygen vacancies. (orig.)

  1. Estimation of multi-group cross section covariances for {sup 235,238}U, {sup 239}Pu, {sup 241}Am, {sup 56}Fe, {sup 23}Na and {sup 27}Al

    Energy Technology Data Exchange (ETDEWEB)

    De Saint Jean, C.; Archier, P.; Noguere, G.; Litaize, O.; Vaglio-Gaudard, C.; Bernard, D.; Leray, O. [CEA, DEN, DER, Cadarache, F-13108 Saint-Paul-lez-Durance (France)

    2012-07-01

    This paper presents the methodology used to estimate multi-group covariances for some major isotopes used in reactor physics. The starting point of this evaluation is the modelling of the neutron induced reactions based on nuclear reaction models with parameters. These latest are the vectors of uncertainties as they are absorbing uncertainties and correlation arising from the confrontation of nuclear reaction model to microscopic experiment. These uncertainties are then propagated towards multi-group cross sections. As major breakthroughs were then asked by nuclear reactor physicists to assess proper uncertainties to be used in applications, a solution is proposed by the use of integral experiment information at two different stages in the covariance estimation. In this paper, we will explain briefly the treatment of all type of uncertainties, including experimental ones (statistical and systematic) as well as those coming from validation of nuclear data on dedicated integral experiment (nuclear data oriented). We will illustrate the use of this methodology with various isotopes such as {sup 235,238}U, {sup 239}Pu, {sup 241}Am, {sup 56}Fe, {sup 23}Na and {sup 27}Al. (authors)

  2. Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Malki, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Mekhalif, Z.; Detriche, S.; Fonder, G. [Laboratoire de Chimie et Electrochimie des Surfaces, Facultés Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, B-5000 Namur (Belgium); Boumaza, A., E-mail: charif_boumaza@yahoo.com [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Djelloul, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria)

    2014-07-01

    The changes caused by heat treatment of gibbsite powder at 300–1473 K were studied using the X-ray diffraction (XRD), X-ray photoemission (XPS) spectra and {sup 27}Al magic angle spinning nuclear magnetic resonance spectroscopy ({sup 27}Al MAS NMR). XRD analysis indicates that the transformation sequence involves the formation of κ-Al{sub 2}O{sub 3} as an intermediate phase between χ- and α-Al{sub 2}O{sub 3}. The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. XPS analysis indicates that the ratio of aluminium atoms to oxygen atoms in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3} increases, whereas the expected ratio is observed in α-Al{sub 2}O{sub 3}. The percentage of AlO{sub 4} units in the transition aluminas follows the same behaviour as the ratio of Al/O. - Graphical abstract: The percentage of AlO{sub 4} units in transition aluminas follows the same behaviour as the ratio of Al/O. - Highlights: • Calcination products of gibbsite studied by XRD, XPS and solid-state NMR. • The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. • The Al/O atomic ratio determined by XPS is larger than 2/3 in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3}. • The percentage of AlO{sub 4} in the aluminas follows the same behaviour as the Al/O atomic ratio.

  3. Transformer-coupled NMR probe

    Science.gov (United States)

    Utsuzawa, Shin; Mandal, Soumyajit; Song, Yi-Qiao

    2012-03-01

    In this study, we propose an NMR probe circuit that uses a transformer with a ferromagnetic core for impedance matching. The ferromagnetic core provides a strong but confined coupling that result in efficient energy transfer between the sample coil and NMR spectrometer, while not disturbing the B1 field generated by the sample coil. We built a transformer-coupled NMR probe and found that it offers comparable performance (loss NQR.

  4. Magic Angle Spinning NMR Metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Z.

    2016-05-31

    Nuclear Magnetic Resonance (NMR) spectroscopy is a non-destructive, quantitative, reproducible, untargeted and unbiased method that requires no or minimal sample preparation, and is one of the leading analytical tools for metabonomics research [1-3]. The easy quantification and the no need of prior knowledge about compounds present in a sample associated with NMR are advantageous over other techniques [1,4]. 1H NMR is especially attractive because protons are present in virtually all metabolites and its NMR sensitivity is high, enabling the simultaneous identification and monitoring of a wide range of low molecular weight metabolites.

  5. Tannin Fingerprinting in Vegetable Tanned Leather by Solid State NMR Spectroscopy and Comparison with Leathers Tanned by Other Processes

    Directory of Open Access Journals (Sweden)

    Jan H. van der Westhuizen

    2011-01-01

    Full Text Available Solid state 13C-NMR spectra of pure tannin powders from four different sources – mimosa, quebracho, chestnut and tara – are readily distinguishable from each other, both in pure commercial powder form, and in leather which they have been used to tan.  Groups of signals indicative of the source, and type (condensed vs. hydrolyzable of tannin used in the manufacture are well resolved in the spectra of the finished leathers.  These fingerprints are compared with those arising from leathers tanned with other common tanning agents.  Paramagnetic chromium (III tanning causes widespread but selective disappearance of signals from the spectrum of leather collagen, including resonances from acidic aspartyl and glutamyl residues, likely bound to Cr (III structures. Aluminium (III and glutaraldehyde tanning both cause considerable leather collagen signal sharpening suggesting some increase in molecular structural ordering. The 27Al-NMR signal from the former material is consistent with an octahedral coordination by oxygen ligands. Solid state NMR thus provides easily recognisable reagent specific spectral fingerprints of the products of vegetable and some other common tanning processes. Because spectra are related to molecular properties, NMR is potentially a powerful tool in leather process enhancement and quality or provenance assurance.

  6. NMR Studies of 3-Acylcamphor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    NMR studies of some chiral 3-acyclcamphor were conducted.A complete assignment was given to 3-(4-pyridyl)carbonylcamphor by the 2D NMR technology.Assignments were also given to other b -diketones.The results showed that those 3-acylcamphors exist in the enol forms,while 2-benzoyl menthone exists in diketon form.

  7. 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.

  8. 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.

  9. 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...

  10. NMR molecular photography

    CERN Document Server

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

    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 signals can be excited, resulting in a spectrum showing many sharp peaks with controllable frequencies and amplitudes. The spectral resolution is enhanced by using a second weak pulse with a 90 phase shift, so that the 1024 bits of information can be retrieved as a set of well-resolved pseudo-2D spectra reproducing the input pattern.

  11. Gel synthesis of an albite (NaAlSi[sub 3]O[sub 8]) glass: An NMR analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schmelz, C.E.; Stebbins, J.F. (Stanford Univ., CA (United States))

    1993-08-01

    The authors have extended the range and complexity of glasses formed by the combination of metal-alkoxides by synthesizing a clear, homogeneous gel of albite (NaAlSi[sub 3]O[sub 8]) composition and heat-treating it to make a densified glass. Systematic changes in [sup 29]Si, [sup 27]Al, and [sup 23]Na NMR spectra of gels with heat treatment are similar to differences in published spectra of hydrated albite glasses with varying water contents. The [sup 29]Si spectra showed one peak; if Q[sup 3](OH) species are present in the samples, it is not obvious in the spectra. Analysis of the rate of spin transfer in CPMAS experiments suggests a Si-H distance [approximately]15% shorter than that seen in Q[sup 3](OH) species in silica gel. Both the [sup 27]Al and [sup 23]Na peaks show an increase in quadrupolar broadening with heat treatment of the gel. Two peaks are present in the [sup 23]Na spectra for gels heat-treated to 300 and 500[degrees]C, possibly due to sites with different sodium coordination. It is proposed that the differences in spectra can be explained by the differences in volatile content of the samples (including water as either H[sub 2]O or OH[sup [minus

  12. A solid state NMR study of layered double hydroxides intercalated with para-amino salicylate, a tuberculosis drug

    DEFF Research Database (Denmark)

    Jensen, Nicholai Daugaard; Bjerring, Morten; Nielsen, Ulla Gro

    2016-01-01

    Para-amino salicylate (PAS), a tubercolosis drug, was intercalated in three different layered double hydroxides (MgAl, ZnAl, and CaAl-LDH) and the samples were studied by multi-nuclear (1H, 13C, and 27Al) solid state NMR (SSNMR) spectroscopy in combination with powder X-ray diffraction (PXRD......), elemental analysis and IR-spectroscopy to gain insight into the bulk and atomic level structure of these LDHs especially with a view to the purity of the LDH-PAS materials and the concentration of impurities. The intercalations of PAS in MgAl-, ZnAl-, and CaAl-LDH's were confirmed by 13C SSNMR and PXRD...... showed that the M(II):Al ratio was higher than predicted from the bulk metal composition of MgAl-PAS and ZnAl-PAS. Moreover, the first high-resolution 1H SSNMR spectra of a CaAl LDH is reported and assigned using 1H single and double quantum experiments in combination with 27Al{1H} HETCOR....

  13. Investigating the Surface Structure of γ-Al 2 O 3 Supported WO X Catalysts by High Field 27 Al MAS NMR and Electronic Structure Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chuan; Hu, Mary Y.; Jaegers, Nicholas R.; Shi, Dachuan; Wang, Huamin; Gao, Feng; Qin, Zhaohai; Wang, Yong; Hu, Jian Zhi

    2016-10-13

    The metal-support interaction in γ-Al2O3 supported WOX catalysts is investigated by a combination of high field quantitative single pulse (SP) 27Al MAS NMR spectroscopy, 2D MQMAS, 1H-27Al CP/MAS, and electronic structure calculations. NMR allows the observation of at least seven different Al sites, including a pentahedral Al site, three different tetrahedral Al sites, and three octahedral Al sites. It is found that the penta-coordinated Al (AlP) site density decreases monotonically with an increased WOX loading while the octahedral Al (AlO) site density increases concurrently. This suggests that the Alp sites are the preferred surface anchoring positions for the WOX species. Importantly, the AlP site isotropic chemical shift observed for the unsupported γ-Al2O3 at about 38 ppm migrates into the octahedral region with a new isotropic chemical shift value appearing near 7 ppm when the Alp site is anchored by WOX species. Density functional theory (DFT) computational modeling of the NMR parameters on proposed cluster models is carried out to accurately interpret the dramatic chemical shift changes from which the detailed anchoring mechanisms are obtained. It is found that tungsten dimers and monomers are the preferred supported surface species on γ-Al2O3, wherein one monomeric and several dimeric structures are identified as the most likely surface anchoring structures.

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

    African Journals Online (AJOL)

    Preferred Customer

    various fields of science and industry such as microelectronic and aerospace ... GIAO/DFT (Gauge Including Atomic Orbitals/Density Functional Theory) approach is .... successfully by using NMR and quantum chemical calculations.

  15. NMR spectrometers as "magnetic tongues"

    DEFF Research Database (Denmark)

    Malmendal, Anders; Amoresano, Claudia; Trotta, Roberta

    2011-01-01

    opened up the possibility to calibrate the sensory perception. In this frame, we have tested the potentiality of nuclear magnetic resonance spectroscopy as a predictive tool to measure sensory descriptors. In particular, we have used an NMR metabolomic approach that allowed us to differentiate...... 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...

  16. 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

  17. An NMR Evidence of Sharp Features in the Pseudogap of Quasicrystals

    Science.gov (United States)

    Tang, X.-P.; Wonnell, S. K.; Hill, E. A.; Wu, Y.; Poon, S. J.

    1997-03-01

    The electronic properties of the quasicrystals have been studied by ^27Al, ^63Cu and ^65Cu NMR. The nuclear spin- lattice relaxation rate was found to obey a universal T^2 temperature dependence over a wide temperature range (90K-500K) in quasicrystalline i-AlCuRu, i-AlCuFe, i-AlPdRe and crystalline approximant α-AlMnSi. The relaxation mechanism was proven to be electronic in origin. This unconventional temperature dependence is a clear evidence of a sharp feature in the electronic density-of-state (DOS) near the Fermi level E_F, N(E)=N_0[1+(|E-E_F|/Δ)^1/2]. A weak temperature dependence of the Knight shift K ∝ T^1/2, as a result of this type of DOS was also observed. Such DOS was expected for a Van Hove-type singularity as well as theoretical predictions based on the model of hierarchy of clusters(C. Janot et. al., Phys. Rev. Lett. 72, 1674(1994)). Our NMR study suggests that it is a common feature in quasicrystals. It was found that i-AlPdRe, i- AlCuRu possess sharper pseudogaps and smaller N(E_F) than in the other samples, in agreement with the established heat capacity, electric conductivity measurements.

  18. β-NMR sample optimization

    CERN Document Server

    Zakoucka, Eva

    2013-01-01

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

  19. 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 ).

  20. Compact orthogonal NMR field sensor

    Science.gov (United States)

    Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL

    2009-02-03

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

  1. Optical pumping and xenon NMR

    Energy Technology Data Exchange (ETDEWEB)

    Raftery, M. Daniel [Univ. of California, Berkeley, CA (United States)

    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 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.

  2. 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.

  3. NMR characterization of thin films

    Science.gov (United States)

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

    2008-11-25

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

  4. Weight Management Guides for Pregnant Women with a Body Mass index (BMI) Greater than or Equal to 40kg/m[Superscript 2]: A Qualitative Exploration of Their Use in Maternity Care

    Science.gov (United States)

    Smith, Debbie M.; Ward, Christine; Forbes, Shareen; Reynolds, Rebecca M.; Denison, Fiona C.

    2013-01-01

    Objective: Maternal obesity (Body Mass Index [BMI] greater than or equal to 30kg/m([superscript 2]) is associated with numerous maternal and fetal complications. Recent guidelines have called for advice to be given to women as pregnancy is a good time for intervention as due to women's motivations for change being high and changes may impact on…

  5. Weight Management Guides for Pregnant Women with a Body Mass index (BMI) Greater than or Equal to 40kg/m[Superscript 2]: A Qualitative Exploration of Their Use in Maternity Care

    Science.gov (United States)

    Smith, Debbie M.; Ward, Christine; Forbes, Shareen; Reynolds, Rebecca M.; Denison, Fiona C.

    2013-01-01

    Objective: Maternal obesity (Body Mass Index [BMI] greater than or equal to 30kg/m([superscript 2]) is associated with numerous maternal and fetal complications. Recent guidelines have called for advice to be given to women as pregnancy is a good time for intervention as due to women's motivations for change being high and changes may impact on…

  6. Consecutive C[subscript 60] Fullerene Dissociation from Ir([eta][superscript 2]-C[subscript 60])(CO)(Cl)(PPh[subscript 3])[subscript 2] and the Oxidative Addition of Benzene

    Science.gov (United States)

    Felix, Tamara; Cortes-Figueroa, Jose E.

    2010-01-01

    This laboratory activity is a mechanistic exploration of the interactions between electronically deficient organometallic compounds and solvent molecules. Simple kinetics experiments designed to explore the mechanism of C[subscript 60] fullerene-benzene exchange on Ir(([eta][superscript 2]-C[subscript 60])(CO)(Cl)(PPh[subscript 3])[subscript 2]…

  7. Project h[schwa]li?dx[superscript w]/Healthy Hearts across Generations: Development and Evaluation Design of a Tribally Based Cardiovascular Disease Prevention Intervention for American Indian Families

    Science.gov (United States)

    Walters, Karina L.; LaMarr, June; Levy, Rona L.; Pearson, Cynthia; Maresca, Teresa; Mohammed, Selina A.; Simoni, Jane M.; Evans-Campbell, Teresa; Fredriksen-Goldsen, Karen; Fryberg, Sheryl; Jobe, Jared B.

    2012-01-01

    American Indian and Alaska Native (AIAN) populations are disproportionately at risk for cardiovascular disease (CVD), diabetes, and obesity, compared with the general US population. This article describes the h[schwa]li?dx[superscript w]/Healthy Hearts Across Generations project, an AIAN-run, tribally based randomized controlled trial (January…

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

    Energy Technology Data Exchange (ETDEWEB)

    Matwiyoff, N.A.

    1983-01-01

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

  9. 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.

  10. The aluminium effect on the structure of silico-phosphate glasses studied by NMR and FTIR

    Science.gov (United States)

    Sitarz, Maciej; Fojud, Zbigniew; Olejniczak, Zbigniew

    2009-04-01

    Silico-phosphate glasses of NaCaPO 4-SiO 2 and NaCaPO 4-AlPO 4-SiO 2 system have been the subject of the presented investigations. Glasses of these systems are the basis for the preparation of glassy-crystalline biomaterials [R.D. Rawlings, Clin. Mater. 14 (1993) 155]. Detailed knowledge of the precursor glass structure is necessary for proper design of the glassy-crystalline biomaterials preparation procedure. Since there is no long-range ordering in glasses, spectroscopic methods which make it possible to study the short range ordering should be applied. MIR studies carried out in the work have allowed to establish that the glasses of the systems studied show domain composition [L.L. Hench, R.J. Splinter, T.K. Greenlee, W.C. Allen, J. Biol. Res. Symp. 2 (1971) 117; L.L. Hench, R.J. Splinter, W.C. Allen, T.K. Greenlee, J. Biol. Res. 5 (1972) 117]. Domain structure is close to that of the corresponding crystalline phases. It has been shown that even small amount of aluminium in the glass (5 mol.% of AlPO 4) significantly influences both, its texture (microscopic and EDX studies) and its structure (spectroscopic studies). 27Al NMR investigations have made it possible to establish unequivocally that aluminium occurs exclusively in tetrahedral coordination, i.e. it is involved in the formation of glass framework. Presence of aluminium results in significant changes in the [SiO 4] 4- and [PO 4] 3- tetrahedra environment which is reflected in 23Na, 31P and 29Si NMR spectra. Changes in the shapes and positions of the bands in the NMR spectra of glasses belonging to the NaCaPO 4-AlPO 4-SiO 2 system confirm great influence of aluminium on silico-phosphate glasses structure.

  11. Geochemical kinetics via the Swift-Connick equations and solution NMR

    Science.gov (United States)

    Harley, Steven J.; Ohlin, C. André; Casey, William H.

    2011-07-01

    Signal analysis in Nuclear Magnetic Resonance spectroscopy is among the most powerful methods to quantify reaction rates in aqueous solutions. To this end, the Swift-Connick approximations to the Bloch-McConnell equations have been used extensively to estimate rate parameters for elementary reactions. The method is primarily used for 17O NMR in aqueous solutions, but the list of geochemically relevant nuclei that can be used is long, and includes 29Si, 27Al, 19F, 13C and many others of particular interest to geochemists. Here we review the derivation of both the Swift-Connick and Bloch-McConnell equations and emphasize assumptions and quirks. For example, the equations were derived for CW-NMR, but are used with modern pulse FT-NMR and can be applied to systems that have exchange rates that are shorter than the lifetime of a typical pulse. The method requires a dilute solution where the minor reacting species contributes a negligible amount of total magnetization. We evaluate the sensitivity of results to this dilute-solution requirement and also highlight the need for chemically well-defined systems if reliable data are to be obtained. The limitations in using longitudinal relaxation to estimate reaction rate parameters are discussed. Finally, we provide examples of the application of the method, including ligand exchanges from aqua ions and hydrolysis complexes, that emphasize its flexibility. Once the basic requirements of the Swift-Connick method are met, it allows geochemists to establish rates of elementary reactions. Reactions at this scale lend themselves well to methods of computational simulation and could provide key tests of accuracy.

  12. NMR studies of actinide dioxides

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)], E-mail: tokunaga.yo@jaea.go.jp; Sakai, H.; Fujimoto, T.; Kambe, S.; Walstedt, R.E.; Ikushima, K.; Yasuoka, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Aoki, D.; Homma, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Haga, Y.; Matsuda, T.D.; Ikeda, S.; Yamamoto, E.; Nakamura, A. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Shiokawa, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nakajima, K.; Arai, Y. [Department of Nuclear Energy System, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2007-10-11

    {sup 17}O NMR measurements have been performed on a series of the actinide dioxides, UO{sub 2}, NpO{sub 2} and PuO{sub 2}. Although the {sup 17}O NMR spectra in these materials are similar at higher temperatures, the low-temperature spectra present are significantly different. In UO{sub 2} we have observed a wide spectrum, forming a rectangular shape below T{sub N}=30 K. In NpO{sub 2}, on the other hand, the spectra broaden rather gradually and exhibit a two-peak structure below T{sub 0}=26 K. In PuO{sub 2}, neither spectrum broadening nor splitting has been observed. We show that these NMR spectra clearly indicate the different nature of the low-temperature magnetic ground states in these actinide compounds.

  13. NMR and dynamics of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Lian, L.Y.; Barsukov, I.L. [Leicester Univ. (United Kingdom)

    1994-12-31

    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.

  14. Spectral Estimation of NMR Relaxation

    Science.gov (United States)

    Naugler, David G.; Cushley, Robert J.

    2000-08-01

    In this paper, spectral estimation of NMR relaxation is constructed as an extension of Fourier Transform (FT) theory as it is practiced in NMR or MRI, where multidimensional FT theory is used. nD NMR strives to separate overlapping resonances, so the treatment given here deals primarily with monoexponential decay. In the domain of real error, it is shown how optimal estimation based on prior knowledge can be derived. Assuming small Gaussian error, the estimation variance and bias are derived. Minimum bias and minimum variance are shown to be contradictory experimental design objectives. The analytical continuation of spectral estimation is constructed in an optimal manner. An important property of spectral estimation is that it is phase invariant. Hence, hypercomplex data storage is unnecessary. It is shown that, under reasonable assumptions, spectral estimation is unbiased in the context of complex error and its variance is reduced because the modulus of the whole signal is used. Because of phase invariance, the labor of phasing and any error due to imperfect phase can be avoided. A comparison of spectral estimation with nonlinear least squares (NLS) estimation is made analytically and with numerical examples. Compared to conventional sampling for NLS estimation, spectral estimation would typically provide estimation values of comparable precision in one-quarter to one-tenth of the spectrometer time when S/N is high. When S/N is low, the time saved can be used for signal averaging at the sampled points to give better precision. NLS typically provides one estimate at a time, whereas spectral estimation is inherently parallel. The frequency dimensions of conventional nD FT NMR may be denoted D1, D2, etc. As an extension of nD FT NMR, one can view spectral estimation of NMR relaxation as an extension into the zeroth dimension. In nD NMR, the information content of a spectrum can be extracted as a set of n-tuples (ω1, … ωn), corresponding to the peak maxima

  15. Chromium liquid waste inertization in an inorganic alkali activated matrix: Leaching and NMR multinuclear approach

    Energy Technology Data Exchange (ETDEWEB)

    Ponzoni, Chiara, E-mail: chiara.ponzoni@unimore.it [University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena (Italy); Lancellotti, Isabella; Barbieri, Luisa [University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena (Italy); Spinella, Alberto; Saladino, Maria Luisa [University of Palermo CGA-UniNetLab, Palermo (Italy); Martino, Delia Chillura [University of Palermo, Department STEBICEF, Palermo (Italy); Caponetti, Eugenio [University of Palermo CGA-UniNetLab, Palermo (Italy); University of Palermo, Department STEBICEF, Palermo (Italy); Armetta, Francesco [University of Palermo, Department STEBICEF, Palermo (Italy); Leonelli, Cristina [University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena (Italy)

    2015-04-09

    Highlights: • Inertization of chromium liquid waste in aluminosilicate matrix. • Water less inertization technique exploiting the waste water content. • Liquid waste inertization without drying step. • Long term stabilization study through leaching test. • SEM analysis and {sup 29}Si and {sup 27}Al MAS NMR in relation with long curing time. - Abstract: A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process - from the precursor dissolution to the final geopolymer matrix hardening - of different geopolymers containing a waste amount ranging from 3 to 20% wt and their capability to inertize chromium cations were studied by: i) the leaching tests, according to the EN 12,457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the aluminosilicate matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of T−O−T bonds (where T is Al or Si) by {sup 29}Si and {sup 27}Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for

  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. 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...

  18. "Solvent Effects" in 1H NMR Spectroscopy.

    Science.gov (United States)

    Cavaleiro, Jose A. S.

    1987-01-01

    Describes a simple undergraduate experiment in chemistry dealing with the "solvent effects" in nuclear magnetic resonance (NMR) spectroscopy. Stresses the importance of having students learn NMR spectroscopy as a tool in analytical chemistry. (TW)

  19. Proton detection of MAS solid-state NMR spectra of half-integer quadrupolar nuclei.

    Science.gov (United States)

    Venkatesh, Amrit; Hanrahan, Michael P; Rossini, Aaron J

    Fast magic angle spinning (MAS) and proton detection has found widespread application to enhance the sensitivity of solid-state NMR experiments with spin-1/2 nuclei such as (13)C, (15)N and (29)Si, however, this approach is not yet routinely applied to half-integer quadrupolar nuclei. Here we have investigated the feasibility of using fast MAS and proton detection to enhance the sensitivity of solid-state NMR experiments with half-integer quadrupolar nuclei. The previously described dipolar hetero-nuclear multiple quantum correlation (D-HMQC) and dipolar refocused insensitive nuclei enhanced by polarization transfer (D-RINEPT) pulse sequences were used for proton detection of half-integer quadrupolar nuclei. Quantitative comparisons of signal-to-noise ratios and the sensitivity of proton detected D-HMQC and D-RINEPT and direct detection spin echo and quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) solid-state NMR spectra, demonstrate that one dimensional proton detected experiments can provide sensitivity similar to or exceeding that obtainable with direct detection QCPMG experiments. 2D D-HMQC and D-RINEPT experiments provide less sensitivity than QCPMG experiments but proton detected 2D hetero-nuclear correlation solid-state NMR spectra of half-integer nuclei can still be acquired in about the same time as a 1D spin echo spectrum. Notably, the rarely used D-RINEPT pulse sequence is found to provide similar, or better sensitivity than D-HMQC in some cases. Proton detected D-RINEPT benefits from the short longitudinal relaxation times (T1) normally associated with half-integer quadrupolar nuclei, it can be combined with existing signal enhancement methods for quadrupolar nuclei, and t1-noise in the indirect dimension can easily be removed by pre-saturation of the (1)H nuclei. The rapid acquisition of proton detected 2D HETCOR solid-state NMR spectra of a range of half-integer quadrupolar nuclei such as (17)O, (27)Al, (35)Cl and (71)Ga is demonstrated. Copyright

  20. 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,

  1. NMR and NQR study of Si-doped (6,0) zigzag single-walled aluminum nitride nanotube as n or P-semiconductors.

    Science.gov (United States)

    Baei, Mohammad T; Peyghan, Ali Ahmadi; Tavakoli, Khadijeh; Babaheydari, Ali Kazemi; Moghimi, Masoumeh

    2012-09-01

    Density functional theory (DFT) calculations were performed to investigate the electronic structure properties of pristine and Si-doped aluminum nitride nanotubes as n or P-semiconductors at the B3LYP/6-31G* level of theory in order to evaluate the influence of Si-doped in the (6,0) zigzag AlNNTs. We extended the DFT calculation to predict the electronic structure properties of Si-doped aluminum nitride nanotubes, which are very important for production of solid-state devices and other applications. To this aim, pristine and Si-doped AlNNT structures in two models (Si(N) and Si(Al)) were optimized, and then the electronic properties, the isotropic (CS(I)) and anisotropic (CS(A)) chemical shielding parameters for the sites of various (27)Al and (14)N atoms, NQR parameters for the sites of various of (27)Al and (14)N atoms, and quantum molecular descriptors were calculated in the optimized structures. The optimized structures, the electronic properties, NMR and NQR parameters, and quantum molecular descriptors for the Si(N) and Si(Al) models show that the Si(N) model is a more reactive material than the pristine or Si(Al) model.

  2. Time domain NMR applied to food products

    NARCIS (Netherlands)

    Duynhoven, van J.P.M.; Voda, A.; Witek, M.M.; As, van H.

    2010-01-01

    Time-domain NMR is being used throughout all areas of food science and technology. A wide range of one- and two-dimensional relaxometric and diffusometric applications have been implemented on cost-effective, robust and easy-to-use benchtop NMR equipment. Time-domain NMR applications do not only

  3. Investigations of adsorption sites on oxide surfaces using solid-state NMR and TPD-IGC

    Science.gov (United States)

    Golombeck, Rebecca A.

    diameters and thermal histories. The bulk structural features in both compositions of glass fibers were identified using high-resolution 29Si, 27Al, and 11B magic-angle spinning (MAS) NMR spectroscopic measurements. In multi-component glasses, the determination of silicon, aluminum, and boron distributions becomes difficult due to the competitive nature of the network-modifying oxides among the network-forming oxides. In pure silicates, 29Si MAS NMR can often resolve resonances arising from silicate tetrahedron having varying numbers of bridging oxygens. In aluminoborosilicate glasses, aluminum is present in four-, five-, and six- coordination with oxygen as neighbors. The speciation of the aluminum can be determined using 27Al MAS NMR. The fraction of tetrahedral boron species in the glass fibers were measured using 11B MAS NMR, which is typically used to study the short-range structure of borate containing glasses such as alkali borate, borosilicate, and aluminoborosilicate glasses. While solid-state NMR is a powerful tool for elucidating bonding environments and coordination changes in the glass structure, it cannot quantitatively probe low to moderate surface area samples due to insufficient spins. Chemical probes either physisorbed or chemisorbed to the fiber's surface can increase the surface selectivity of NMR for analysis of samples with low surface areas and provide information about the local molecular structure of the reactive surface site. Common chemical probe molecules contain NMR active nuclei such as 19F or may be enriched with 13C. A silyating agent, (3,3,3-trifluoropropyl)dimethylchlorosilane (TFS), reacts with reactive surface hydroxyls, which can be quantified by utilizing the NMR active nucleus (19F) contained in the probe molecule. The observed 19F MAS NMR peak area is integrated and compared against a standard of known fluorine spins (concentration), allowing the number of reactive hydroxyl sites to be quantified. IGC is a method used to study the

  4. Direct Characterization of Kerogen by X-ray and Solid-State [superscript 13]C Nuclear Magnetic Resonance Methods

    Energy Technology Data Exchange (ETDEWEB)

    Kelemen, S. R.; Afeworki, M.; Gorbaty, M.L.; Sansone, M.; Kwiatek, P.J.; Walters, C.C.; Freund, H.; Siskin, M.; Bence, A.E.; Curry, D.J.; Solum, M.; Pugmire, R.J.; Vandenbroucke, M.; Leblond, M.; Behar, F. (ExxonMobil); (ExxonMobil); (IFP); (Utah)

    2008-06-12

    A combination of solid-state {sup 13}C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between the Rock-Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice parameters are derived from solid-state {sup 13}C NMR analysis. As expected, the amount of aromatic carbon, measured by both {sup 13}C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and Rock-Eval T{sub max}, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter type follows a different relationship. The average aliphatic carbon chain length (Cn) decreases with an increasing amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12 to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted. There is basic agreement between XPS and {sup 13}C NMR results for the amount and speciation of organic oxygen. XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl-carboxyl species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur seen in the

  5. ELISE NMR: Experimental liquid sealing of NMR samples

    Science.gov (United States)

    Wieruszeski, Jean-Michel; Landrieu, Isabelle; Hanoulle, Xavier; Lippens, Guy

    2006-08-01

    We present a simple, generally applicable approach to prevent sample evaporation when working at elevated temperatures in high resolution NMR. It consists of experimentally sealing the NMR sample by a second liquid (Experimental Liquid Sealing, ELISE). For aqueous samples, we identified the mineral oil commonly used in PCR application as the best candidate, because it contains only a very limited amount of water-soluble contaminants, is stable over time and heat resistant. The procedure does not interfere with shim settings, and is compatible with a wide variety of samples, including oligosaccharides and proteins. For chloroform samples, a simple drop of water allows to efficiently seal the sample, avoiding solvent evaporation even over lengthy time periods.

  6. 27Al, 47,49Ti, 31P, and 13C MAS NMR Study of VX, GD, and HD Reactions with Nanosize Al2O3, Conventional Al2O3 and TiO2, and Aluminum and Titanium Metal

    Science.gov (United States)

    2007-01-01

    pH ,3 compared to that of 1 which is insoluble at neutral pH . Thus, the sharpness of the peak for 2 is attributed to increased motion as a result of...O’Connor, R. J.; Munavalli, S.; Carnes , C. L.; Kapoor, P. N.; Klabunde, K. J. J. Am. Chem. Soc. 2001, 123, 1636-1644. (4) (a) Mehring, M.; Guerrero, G

  7. Experience[superscript]2

    Science.gov (United States)

    Barker, Kim

    2011-01-01

    Researching whimsical and spirited artists can inspire new ideas and methods of communicating how art remains a valuable part of people's lives both in and out of the classroom. This instructional resource explores one such contemporary artist who, driven by a curiosity in human interaction, continues to explore the world in fanciful and…

  8. 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.

  9. 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.

  10. Hyperpolarized 131Xe NMR spectroscopy

    Science.gov (United States)

    Stupic, Karl F.; Cleveland, Zackary I.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2011-01-01

    Hyperpolarized (hp) 131Xe with up to 2.2% spin polarization (i.e., 5000-fold signal enhancement at 9.4 T) was obtained after separation from the rubidium vapor of the spin-exchange optical pumping (SEOP) process. The SEOP was applied for several minutes in a stopped-flow mode, and the fast, quadrupolar-driven T1 relaxation of this spin I = 3/2 noble gas isotope required a rapid subsequent rubidium removal and swift transfer into the high magnetic field region for NMR detection. Because of the xenon density dependent 131Xe quadrupolar relaxation in the gas phase, the SEOP polarization build-up exhibits an even more pronounced dependence on xenon partial pressure than that observed in 129Xe SEOP. 131Xe is the only stable noble gas isotope with a positive gyromagnetic ratio and shows therefore a different relative phase between hp signal and thermal signal compared to all other noble gases. The gas phase 131Xe NMR spectrum displays a surface and magnetic field dependent quadrupolar splitting that was found to have additional gas pressure and gas composition dependence. The splitting was reduced by the presence of water vapor that presumably influences xenon-surface interactions. The hp 131Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp 131Xe NMR spectroscopy studies, a general equation for the high temperature, thermal spin polarization, P, for spin I⩾1/2 nuclei is presented.

  11. Glyphosate complexation to aluminium(III). An equilibrium and structural study in solution using potentiometry, multinuclear NMR, ATR-FTIR, ESI-MS and DFT calculations.

    Science.gov (United States)

    Purgel, Mihály; Takács, Zoltán; Jonsson, Caroline M; Nagy, Lajos; Andersson, Ingegärd; Bányai, István; Pápai, Imre; Persson, Per; Sjöberg, Staffan; Tóth, Imre

    2009-11-01

    The stoichiometries and stability constants of a series of Al(3+)-N-phosponomethyl glycine (PMG/H(3)L) complexes have been determined in acidic aqueous solution using a combination of precise potentiometric titration data, quantitative (27)Al and (31)P NMR spectra, ATR-FTIR spectrum and ESI-MS measurements (0.6M NaCl, 25 degrees C). Besides the mononuclear AlH(2)L(2+), Al(H(2)L)(HL), Al(HL)(2)(-) and Al(HL)L(2-), dimeric Al(2)(HL)L(+) and trinuclear Al(3)H(5)L(4)(2+) complexes have been postulated. (1)H and (31)P NMR data show that different isomers co-exist in solution and the isomerization reactions are slow on the (31)P NMR time scale. The geometries of monomeric and dimeric complexes likely double hydroxo bridged and double phosphonate bridged isomers have been optimized using DFT ab initio calculations starting from rational structural proposals. Energy calculations using the PCM solvation method also support the co-existence of isomers in solutions.

  12. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sørland, Geir Humborstad

    2014-01-01

    Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

  13. Applications of NMR in Dairy Research

    Directory of Open Access Journals (Sweden)

    Anthony D. Maher

    2014-03-01

    Full Text Available NMR is a robust analytical technique that has been employed to investigate the properties of many substances of agricultural relevance. NMR was first used to investigate the properties of milk in the 1950s and has since been employed in a wide range of studies; including properties analysis of specific milk proteins to metabolomics techniques used to monitor the health of dairy cows. In this brief review, we highlight the different uses of NMR in the dairy industry.

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

    Science.gov (United States)

    Chesick, John P.

    1989-01-01

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

  15. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. Solid-state NMR and Membrane Proteins

    Science.gov (United States)

    Opella, Stanley J.

    2015-01-01

    The native environment for a membrane protein is a phospholipid bilayer. Because the protein is immobilized on NMR timescales by the interactions within a bilayer membrane, solid-state NMR methods are essential to obtain high-resolution spectra. Approaches have been developed for both unoriented and oriented samples, however, they all rest on the foundation of the most fundamental aspects solid-state NMR, and the chemical shift and homo- and hetero-nuclear dipole-dipole interactions. Solid-state NMR has advanced sufficiently to enable the structures of membrane proteins to be determined under near-native conditions in phospholipid bilayers. PMID:25681966

  20. UV-Raman and NMR spectroscopic studies on the crystallization of zeolite A and a new synthetic route.

    Science.gov (United States)

    Ren, Limin; Li, Caijin; Fan, Fengtao; Guo, Qiang; Liang, Desheng; Feng, Zhaochi; Li, Can; Li, Shougui; Xiao, Feng-Shou

    2011-05-23

    UV-Raman and NMR spectroscopy, combined with other techniques, have been used to characterize crystallization of zeolite A. In situ UV-Raman spectroscopy shows that the starting gel for crystallization of zeolite A contains a lot of four-ring (4R) building units and the appearance of six-ring (6R) building blocks is the signal for crystal formation. (29)Si NMR spectroscopy results suggest that the starting gel is double four-ring (D4R) rich and during crystallization of zeolite A both α and β cages appear. (27)Al NMR spectroscopy results indicate the absence of Al (2Si) species in the starting gel, suggesting the absence of single 4R building units in the starting gel. Furthermore, composition analysis of both solid and liquid samples shows that the solid rather than liquid phase predominates for the crystallization of zeolite A. Therefore, it is proposed that the crystallization of zeolite A mainly occurs in the solid phase by self-assembly or rearrangement starting from the zeolite building units mainly consisting of D4R. The essential role of D4R is directly confirmed by successful conversion from a solution of D4R to zeolite A in the presence of NaCl, and the importance of solid phase is reasonably demonstrated by the successful synthesis of zeolite A from a dry aluminosilicate gel. By considering that the solid phase has a major contribution to crystallization, a novel route was designed to synthesizing zeolite A from the raw materials water glass (Na(2)SiO(3) in aqueous solution) and NaAlO(2), without additional water and NaOH; this route not only simplifies synthetic procedures, but reduces water consumption. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

    Mills, Nancy S.; Shanklin, Michael

    2011-01-01

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

  2. Enzyme dynamics from NMR spectroscopy.

    Science.gov (United States)

    Palmer, Arthur G

    2015-02-17

    CONSPECTUS: Biological activities of enzymes, including regulation or coordination of mechanistic stages preceding or following the chemical step, may depend upon kinetic or equilibrium changes in protein conformations. Exchange of more open or flexible conformational states with more closed or constrained states can influence inhibition, allosteric regulation, substrate recognition, formation of the Michaelis complex, side reactions, and product release. NMR spectroscopy has long been applied to the study of conformational dynamic processes in enzymes because these phenomena can be characterized over multiple time scales with atomic site resolution. Laboratory-frame spin-relaxation measurements, sensitive to reorientational motions on picosecond-nanosecond time scales, and rotating-frame relaxation-dispersion measurements, sensitive to chemical exchange processes on microsecond-millisecond time scales, provide information on both conformational distributions and kinetics. This Account reviews NMR spin relaxation studies of the enzymes ribonuclease HI from mesophilic (Escherichia coli) and thermophilic (Thermus thermophilus) bacteria, E. coli AlkB, and Saccharomyces cerevisiae triosephosphate isomerase to illustrate the contributions of conformational flexibility and dynamics to diverse steps in enzyme mechanism. Spin relaxation measurements and molecular dynamics (MD) simulations of the bacterial ribonuclease H enzymes show that the handle region, one of three loop regions that interact with substrates, interconverts between two conformations. Comparison of these conformations with the structure of the complex between Homo sapiens ribonuclease H and a DNA:RNA substrate suggests that the more closed state is inhibitory to binding. The large population of the closed conformation in T. thermophilus ribonuclease H contributes to the increased Michaelis constant compared with the E. coli enzyme. NMR spin relaxation and fluorescence spectroscopy have characterized a

  3. 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…

  4. 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…

  5. Planar microcoil-based microfluidic NMR probes.

    NARCIS (Netherlands)

    Massin, C.; Vincent, F.; Homsy, A.; Ehrmann, K.; Boero, G.; Besse, P-A; Daridon, A.; Verpoorte, E.; de Rooij, N.F.; Popovic, R.S.

    2003-01-01

    Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120

  6. 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…

  7. An Inversion Recovery NMR Kinetics Experiment

    Science.gov (United States)

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

    2011-01-01

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

  8. 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…

  9. Planar microcoil-based microfluidic NMR probes.

    NARCIS (Netherlands)

    Massin, C.; Vincent, F.; Homsy, A.; Ehrmann, K.; Boero, G.; Besse, P-A; Daridon, A.; Verpoorte, E.; de Rooij, N.F.; Popovic, R.S.

    2003-01-01

    Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120

  10. 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.

  11. Challenges and perspectives in quantitative NMR.

    Science.gov (United States)

    Giraudeau, Patrick

    2017-01-01

    This perspective article summarizes, from the author's point of view at the beginning of 2016, the major challenges and perspectives in the field of quantitative NMR. The key concepts in quantitative NMR are first summarized; then, the most recent evolutions in terms of resolution and sensitivity are discussed, as well as some potential future research directions in this field. A particular focus is made on methodologies capable of boosting the resolution and sensitivity of quantitative NMR, which could open application perspectives in fields where the sample complexity and the analyte concentrations are particularly challenging. These include multi-dimensional quantitative NMR and hyperpolarization techniques such as para-hydrogen-induced polarization or dynamic nuclear polarization. Because quantitative NMR cannot be dissociated from the key concepts of analytical chemistry, i.e. trueness and precision, the methodological developments are systematically described together with their level of analytical performance. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. NMR and MRI apparatus and method

    Science.gov (United States)

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

    2007-03-06

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

  13. 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...

  14. Robust, integrated computational control of NMR experiments to achieve optimal assignment by ADAPT-NMR.

    Science.gov (United States)

    Bahrami, Arash; Tonelli, Marco; Sahu, Sarata C; Singarapu, Kiran K; Eghbalnia, Hamid R; Markley, John L

    2012-01-01

    ADAPT-NMR (Assignment-directed Data collection Algorithm utilizing a Probabilistic Toolkit in NMR) represents a groundbreaking prototype for automated protein structure determination by nuclear magnetic resonance (NMR) spectroscopy. With a [(13)C,(15)N]-labeled protein sample loaded into the NMR spectrometer, ADAPT-NMR delivers complete backbone resonance assignments and secondary structure in an optimal fashion without human intervention. ADAPT-NMR achieves this by implementing a strategy in which the goal of optimal assignment in each step determines the subsequent step by analyzing the current sum of available data. ADAPT-NMR is the first iterative and fully automated approach designed specifically for the optimal assignment of proteins with fast data collection as a byproduct of this goal. ADAPT-NMR evaluates the current spectral information, and uses a goal-directed objective function to select the optimal next data collection step(s) and then directs the NMR spectrometer to collect the selected data set. ADAPT-NMR extracts peak positions from the newly collected data and uses this information in updating the analysis resonance assignments and secondary structure. The goal-directed objective function then defines the next data collection step. The procedure continues until the collected data support comprehensive peak identification, resonance assignments at the desired level of completeness, and protein secondary structure. We present test cases in which ADAPT-NMR achieved results in two days or less that would have taken two months or more by manual approaches.

  15. Robust, integrated computational control of NMR experiments to achieve optimal assignment by ADAPT-NMR.

    Directory of Open Access Journals (Sweden)

    Arash Bahrami

    Full Text Available ADAPT-NMR (Assignment-directed Data collection Algorithm utilizing a Probabilistic Toolkit in NMR represents a groundbreaking prototype for automated protein structure determination by nuclear magnetic resonance (NMR spectroscopy. With a [(13C,(15N]-labeled protein sample loaded into the NMR spectrometer, ADAPT-NMR delivers complete backbone resonance assignments and secondary structure in an optimal fashion without human intervention. ADAPT-NMR achieves this by implementing a strategy in which the goal of optimal assignment in each step determines the subsequent step by analyzing the current sum of available data. ADAPT-NMR is the first iterative and fully automated approach designed specifically for the optimal assignment of proteins with fast data collection as a byproduct of this goal. ADAPT-NMR evaluates the current spectral information, and uses a goal-directed objective function to select the optimal next data collection step(s and then directs the NMR spectrometer to collect the selected data set. ADAPT-NMR extracts peak positions from the newly collected data and uses this information in updating the analysis resonance assignments and secondary structure. The goal-directed objective function then defines the next data collection step. The procedure continues until the collected data support comprehensive peak identification, resonance assignments at the desired level of completeness, and protein secondary structure. We present test cases in which ADAPT-NMR achieved results in two days or less that would have taken two months or more by manual approaches.

  16. 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 or as bioactive...

  17. Preprocessing of NMR metabolomics data.

    Science.gov (United States)

    Euceda, Leslie R; Giskeødegård, Guro F; Bathen, Tone F

    2015-05-01

    Metabolomics involves the large scale analysis of metabolites and thus, provides information regarding cellular processes in a biological sample. Independently of the analytical technique used, a vast amount of data is always acquired when carrying out metabolomics studies; this results in complex datasets with large amounts of variables. This type of data requires multivariate statistical analysis for its proper biological interpretation. Prior to multivariate analysis, preprocessing of the data must be carried out to remove unwanted variation such as instrumental or experimental artifacts. This review aims to outline the steps in the preprocessing of NMR metabolomics data and describe some of the methods to perform these. Since using different preprocessing methods may produce different results, it is important that an appropriate pipeline exists for the selection of the optimal combination of methods in the preprocessing workflow.

  18. NMR Hyperpolarization Techniques of Gases.

    Science.gov (United States)

    Barskiy, Danila A; Coffey, Aaron M; Nikolaou, Panayiotis; Mikhaylov, Dmitry M; Goodson, Boyd M; Branca, Rosa T; Lu, George J; Shapiro, Mikhail G; Telkki, Ville-Veikko; Zhivonitko, Vladimir V; Koptyug, Igor V; Salnikov, Oleg G; Kovtunov, Kirill V; Bukhtiyarov, Valerii I; Rosen, Matthew S; Barlow, Michael J; Safavi, Shahideh; Hall, Ian P; Schröder, Leif; Chekmenev, Eduard Y

    2017-01-18

    Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4-8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can often be readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This Minireview covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. 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.

  20. An introduction to biological NMR spectroscopy.

    Science.gov (United States)

    Marion, Dominique

    2013-11-01

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

  1. MAS NMR of HIV-1 protein assemblies

    Science.gov (United States)

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

    2015-04-01

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

  2. Scalar operators in solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Boqin

    1991-11-01

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

  3. NMR reaction monitoring in flow synthesis

    Directory of Open Access Journals (Sweden)

    M. Victoria Gomez

    2017-02-01

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

  4. Oriented solid-state NMR spectrosocpy

    DEFF Research Database (Denmark)

    Bertelsen, Kresten

    This thesis is concerned with driving forward oriented solid-state NMR spectroscopy as a viable technique for studying peptides in membrane bilayers. I will show that structural heterogeneity is an intrinsic part of the peptide/lipid system and that NMR can be used to characterize static...... and dynamic structural features of the peptides and its local surroundings. In fact one need to take into account the dynamical features of the system in order to correctly predict the structure from oriented solid-state NMR spectra.      ...

  5. Graphical programming for pulse automated NMR experiments

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-01-01

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

  6. NMR studies on UPt 3

    Science.gov (United States)

    Kitaoka, Y.; Tou, H.; Ishida, K.; Kimura, N.; Ōnuki, Y.; Yamamoto, E.; Haga, Y.; Maezawa, K.

    2000-06-01

    A complete set of the 195Pt Knight-shift (KS) data on the superconducting (SC) state in UPt 3 identified the spin structure of the Cooper pair corresponding to the multiple SC phases. UPt 3 was acclaimed as the first odd-parity superconductor including a non-unitary pairing state characterized by the two-component d vector like db+ idc at low T and low H [H. Tou et al., Phys. Rev. Lett. 77 (1996) 1374; 80 (1998) 3129]. We have shed further light on these novel results through a comparison with the singlet even-parity anisotropic superconductors CeCu 2Si 2 and UPd 2Al 3. In the singlet pairing state, the fractional decrease in KS below T c, δK obs is independent of the crystal direction. We have found that δ χobs=( NAμ B/ Ahf)δ Kobs where Ahf is the hyperfine coupling constant, is in good agreement with spin susceptibilities χγel calculated from an enhanced electronic specific heat γel and χnmr from the quasiparticle Korringa relation T1TKs2=const. This gives direct evidence that the χs of heavy quasiparticles in CeCu 2Si 2 and UPd 2Al 3 is rather isotropic and decreases to zero as T→0 due to the Cooper-pair formation. On the other hand in UPt 3, the δ χobsb, cs along the b- and c-axis in the non-unitary-pairing state (B phase) are two orders of magnitude smaller than χγel and χnmr. These anomalously small values for δ χobsb, cs may suggest either that the spin degree of freedom in the B phase is not perfectly locked to the a-axis or that χs is not enhanced although γel is. The latter is theoretically pointed out by Ikeda and Miyake [J. Phys. Soc. Japan 66 (1997) 3714] to be possible if 5f electrons in the non-Kramerse singlet ground state for 5f 2 are hybridized with conduction electrons. We need further effort towards coherent understanding of a microscopic mechanism leading to the occurrence of the odd-parity superconductivity in UPt 3.

  7. 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

  8. 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.

  9. NMR and Moessbauer Study of Al{sub 2}O{sub 3}-Eu{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N., E-mail: tnava@imp.mx; Salas, P.; Llanos, M. E. [Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo (Mexico); Perez-Pastenes, H.; Viveros, T. [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de IPH (Mexico)

    2005-02-15

    Alumina-europia mixed oxides with 5 and 10 wt.% Eu{sub 2}O{sub 3} were studied by Moessbauer spectroscopy, {sup 27}Al MAS-NMR and X-ray diffraction (XRD). The samples were prepared by the sol-gel technique. The XRD patterns for the calcined samples show a broad peak around 2{theta} = 30{sup o} which is assigned to the Eu{sub 2}O{sub 3}; after treatment with hydrogen at 1073 K no reduction to Eu{sup +2} or Eu{sup 0} was observed. The NMR spectra show three peaks, which are assigned to the octahedral, pentahedral and tetrahedral aluminum sites; the intensity of each peak depends on the concentration of europium ions. The Moessbauer spectra of the calcined samples show a single peak near zero velocity which is attributed to the Eu{sup +3}; after H{sub 2} treatment at 1073 K similar spectra were obtained, suggesting Eu{sup +3} is not reducibly at this temperature.

  10. MAS NMR, DRIFT, and FT-Raman Characterization of SiO(2)-AlPO(4)-B(2)O(3) Ternary Catalytic Systems.

    Science.gov (United States)

    Aramendía; Boráu; Jiménez; Marinas; Ruiz; Urbano

    1999-09-01

    This work deals with the preparation of SiO(2)-AlPO(4)-B(2)O(3) ternary systems from impregation of a SiO(2)-AlPO(4) solid previously synthesized with B(OH)(3) (0-10% B(OH)(3), by weight). Characterization of the resulting solids has been carried out from adsorption-desorption isotherms of nitrogen, DRIFT, FT-Raman, pyridine adsorption, and (1)H, (11)B, (27)Al, and (31)P MAS NMR. The textural properties are scarcely changed by the impregnation and calcination steps. Moreover, the MAS NMR experiments indicated that the components of the solids do not interact among them. The solids were tested in the dehydration-dehydrogenation of propan-2-ol, widely used to correlate catalytic activity with the surface acid-base properties of the solids. The catalytic results indicate that the effect of boron dopping is an increase in the overall acidity of the solids. Copyright 1999 Academic Press.

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

    Science.gov (United States)

    Alonso, David E.; Warren, Steven E.

    2005-01-01

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

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

    Science.gov (United States)

    Alonso, David E.; Warren, Steven E.

    2005-01-01

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

  13. Bayesian peak picking for NMR spectra.

    Science.gov (United States)

    Cheng, Yichen; Gao, Xin; Liang, Faming

    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. Bayesian Peak Picking for NMR Spectra

    KAUST Repository

    Cheng, Yichen

    2014-02-01

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

  15. Relaxation time estimation in surface NMR

    Science.gov (United States)

    Grunewald, Elliot D.; Walsh, David O.

    2017-03-21

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

  16. NMR analysis of compositional heterogeneity in polysaccharides

    Science.gov (United States)

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

  17. Relaxation time estimation in surface NMR

    Energy Technology Data Exchange (ETDEWEB)

    Grunewald, Elliot D.; Walsh, David O.

    2017-03-21

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

  18. Introduction to NMR Quantum Information Processing

    CERN Document Server

    Laflamme, R; Cory, D G; Fortunato, E M; Havel, T F; Miquel, C; Martínez, R; Negrevergne, C; Ortiz, G; Pravia, M A; Sharf, Y; Sinha, S; Somma, R D; Viola, L

    2002-01-01

    After a general introduction to nuclear magnetic resonance (NMR), we give the basics of implementing quantum algorithms. We describe how qubits are realized and controlled with RF pulses, their internal interactions, and gradient fields. A peculiarity of NMR is that the internal interactions (given by the internal Hamiltonian) are always on. We discuss how they can be effectively turned off with the help of a standard NMR method called ``refocusing''. Liquid state NMR experiments are done at room temperature, leading to an extremely mixed (that is, nearly random) initial state. Despite this high degree of randomness, it is possible to investigate QIP because the relaxation time (the time scale over which useful signal from a computation is lost) is sufficiently long. We explain how this feature leads to the crucial ability of simulating a pure (non-random) state by using ``pseudopure'' states. We discuss how the ``answer'' provided by a computation is obtained by measurement and how this measurement differs f...

  19. 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.

  20. 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.

  1. NMR spectra and potentiometry studies of aluminum(III) binding with coenzyme NAD+ in acidic aqueous solutions.

    Science.gov (United States)

    Yang, Xiaodi; Bi, Shuping; Yang, Xiaoliang; Yang, Li; Hu, Jun; Liu, Jian; Yang, Zhengbiao

    2003-06-01

    Complexation and conformational studies of coenzyme NAD+ with aluminum were conducted in acidic aqueous solutions (pH 2-5) by means of potentiometry as well as multinuclear (1H, 13C, 31P, 27Al) and two-dimensional (1H, 1H-NOESY) NMR spectroscopy. These led to the following results: (1) Al could coordinate with NAD+ through the following binding sites: N7' of adenine and pyrophosphate free oxygen (O(A)1, O(N)1,O(A)2) to form various mononuclear 1:1 (AlLH23+, AlLH2+) and 2:1 (AlL2-) species, and dinuclear 2:2 (Al2L22+) species. (2) The conformations of NAD+ and Al-NAD+ depended on the solvents and different species in the complexes. The results suggest the occurrence of an Al-linked complexation, which causes structural changes at the primary recognition sites and secondary conformational alterations for coenzymes. This finding will help us to understand role of Al in biological enzyme reaction systems.

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

    KAUST Repository

    Kerber, Rachel Nathaniel

    2012-04-18

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

  3. Energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil over a range of energies 0.1-0.6 MeV/u by time-of-flight spectrometry

    Science.gov (United States)

    Guesmia, A.; Ammi, H.; Msimanga, M.; Dib, A.; Mammeri, S.; Pineda-Vargas, C. A.; Hedibel, M.

    2015-02-01

    The energy-loss straggling of 28Si, 27Al, 24Mg, 19F, 16O and 12C partially stripped heavy ions has been determined in Formvar polymeric thin foil over a continuous range of energies 0.1-0.6 MeV/u, by using a powerful method based on the combination of Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique and Time of Flight (ToF) spectrometer. The obtained energy loss straggling values have been analyzed and compared with the corresponding computed values adopting some widely used energy loss straggling formulations such as, Bohr, Bethe-Livingston and Yang formulas. The aim of such a comparison is to check the reliability and accuracy of the existing energy loss straggling formulations. The experimental results of energy loss straggling of all ions are found to be significantly greater than those predicted by the theories. These differences can be attributed to the charge exchange straggling. This effect has to be taken into account in order to explain the obtained results.

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

    Science.gov (United States)

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

    2015-08-01

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

  6. 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…

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

    Science.gov (United States)

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

    2017-01-01

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

  8. 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…

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

    Science.gov (United States)

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

    2017-01-01

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

  10. Characterization of heroin samples by 1H NMR and 2D DOSY 1H NMR.

    Science.gov (United States)

    Balayssac, Stéphane; Retailleau, Emmanuel; Bertrand, Geneviève; Escot, Marie-Pierre; Martino, Robert; Malet-Martino, Myriam; Gilard, Véronique

    2014-01-01

    Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures.

  11. 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......–SPE–NMR-system with a cryogenically cooled probe head, designed for 1.7 mm NMR-tubes. The resulting 1H NMR spectra (600 MHz) were evaluated against a database of previously acquired and prepared spectra. The in-house developed matching algorithm, based on partitioning of the spectra and allowing for changes in the chemical shifts...... and analogues. The database matching of the resulting spectra positively identified expected compounds, while the number of false positives was few and easily recognized....

  12. 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

  13. Theoretical NMR correlations based Structure Discussion

    Directory of Open Access Journals (Sweden)

    Junker Jochen

    2011-07-01

    Full Text Available Abstract The constitutional assignment of natural products by NMR spectroscopy is usually based on 2D NMR experiments like COSY, HSQC, and HMBC. The actual difficulty of the structure elucidation problem depends more on the type of the investigated molecule than on its size. The moment HMBC data is involved in the process or a large number of heteroatoms is present, a possibility of multiple solutions fitting the same data set exists. A structure elucidation software can be used to find such alternative constitutional assignments and help in the discussion in order to find the correct solution. But this is rarely done. This article describes the use of theoretical NMR correlation data in the structure elucidation process with WEBCOCON, not for the initial constitutional assignments, but to define how well a suggested molecule could have been described by NMR correlation data. The results of this analysis can be used to decide on further steps needed to assure the correctness of the structural assignment. As first step the analysis of the deviation of carbon chemical shifts is performed, comparing chemical shifts predicted for each possible solution with the experimental data. The application of this technique to three well known compounds is shown. Using NMR correlation data alone for the description of the constitutions is not always enough, even when including 13C chemical shift prediction.

  14. Radiation damping in microcoil NMR probes.

    Science.gov (United States)

    Krishnan, V V

    2006-04-01

    Radiation damping arises from the field induced in the receiver coil by large bulk magnetization and tends to selectively drive this magnetization back to equilibrium much faster than relaxation processes. The demand for increased sensitivity in mass-limited samples has led to the development of microcoil NMR probes that are capable of obtaining high quality NMR spectra with small sample volumes (nL-microL). Microcoil probes are optimized to increase sensitivity by increasing either the sample-to-coil ratio (filling factor) of the probe or quality factor of the detection coil. Though radiation damping effects have been studied in standard NMR probes, these effects have not been measured in the microcoil probes. Here a systematic evaluation of radiation damping effects in a microcoil NMR probe is presented and the results are compared with similar measurements in conventional large volume samples. These results show that radiation-damping effects in microcoil probe is much more pronounced than in 5 mm probes, and that it is critically important to optimize NMR experiments to minimize these effects. As microcoil probes provide better control of the bulk magnetization, with good RF and B0 inhomogeneity, in addition to negligible dipolar field effects due to nearly spherical sample volumes, these probes can be used exclusively to study the complex behavior of radiation damping.

  15. Magic angle spinning NMR of paramagnetic proteins.

    Science.gov (United States)

    Knight, Michael J; Felli, Isabella C; Pierattelli, Roberta; Emsley, Lyndon; Pintacuda, Guido

    2013-09-17

    Metal ions are ubiquitous in biochemical and cellular processes. Since many metal ions are paramagnetic due to the presence of unpaired electrons, paramagnetic molecules are an important class of targets for research in structural biology and related fields. Today, NMR spectroscopy plays a central role in the investigation of the structure and chemical properties of paramagnetic metalloproteins, linking the observed paramagnetic phenomena directly to electronic and molecular structure. A major step forward in the study of proteins by solid-state NMR came with the advent of ultrafast magic angle spinning (MAS) and the ability to use (1)H detection. Combined, these techniques have allowed investigators to observe nuclei that previously were invisible in highly paramagnetic metalloproteins. In addition, these techniques have enabled quantitative site-specific measurement of a variety of long-range paramagnetic effects. Instead of limiting solid-state NMR studies of biological systems, paramagnetism provides an information-rich phenomenon that can be exploited in these studies. This Account emphasizes state-of-the-art methods and applications of solid-state NMR in paramagnetic systems in biological chemistry. In particular, we discuss the use of ultrafast MAS and (1)H-detection in perdeuterated paramagnetic metalloproteins. Current methodology allows us to determine the structure and dynamics of metalloenzymes, and, as an example, we describe solid-state NMR studies of microcrystalline superoxide dismutase, a 32 kDa dimer. Data were acquired with remarkably short times, and these experiments required only a few milligrams of sample.

  16. NMR structural studies on antifreeze proteins.

    Science.gov (United States)

    Sönnichsen, F D; Davies, P L; Sykes, B D

    1998-01-01

    Antifreeze proteins (AFPs) are a structurally diverse class of proteins that bind to ice and inhibit its growth in a noncolligative manner. This adsorption-inhibition mechanism operating at the ice surface results in a lowering of the (nonequilibrium) freezing point below the melting point. A lowering of approximately 1 degree C, which is sufficient to prevent fish from freezing in ice-laden seawater, requires millimolar AFP levels in the blood. The solubility of AFPs at these millimolar concentrations and the small size of the AFPs (typically 3-15 kDa) make them ideal subjects for NMR analysis. Although fish AFPs are naturally abundant, seasonal expression, restricted access to polar fishes, and difficulties in separating numerous similar isoforms have made protein expression the method of choice for producing AFPs for structural studies. Expression of recombinant AFPs has also facilitated NMR analysis by permitting isotopic labeling with 15N and 13C and has permitted mutations to be made to help with the interpretation of NMR data. NMR analysis has recently solved two AFP structures and provided valuable information about the disposition of ice-binding side chains in a third. The potential exists to solve other AFP structures, including the newly described insect AFPs, and to use solid-state NMR techniques to address fundamental questions about the nature of the interaction between AFPs and ice.

  17. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  18. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  19. Covariance NMR spectroscopy by singular value decomposition.

    Science.gov (United States)

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

    2004-12-01

    Covariance NMR is demonstrated for homonuclear 2D NMR data collected using the hypercomplex and TPPI methods. Absorption mode 2D spectra are obtained by application of the square-root operation to the covariance matrices. The resulting spectra closely resemble the 2D Fourier transformation spectra, except that they are fully symmetric with the spectral resolution along both dimensions determined by the favorable resolution achievable along omega2. An efficient method is introduced for the calculation of the square root of the covariance spectrum by applying a singular value decomposition (SVD) directly to the mixed time-frequency domain data matrix. Applications are shown for 2D NOESY and 2QF-COSY data sets and computational benchmarks are given for data matrix dimensions typically encountered in practice. The SVD implementation makes covariance NMR amenable to routine applications.

  20. NMR detection with an atomic magnetometer

    CERN Document Server

    Savukov, I M

    2004-01-01

    We demonstrate detection of NMR signals using a non-cryogenic atomic magnetometer and describe several novel applications of this technique. A water free induction decay (FID) signal in a 0.5 $\\mu$T field is detected using a spin-exchange-relaxation-free K magnetometer and the possibility of using a multi-channel magnetometer for 3-D MRI requiring only a single FID signal is described. We also demonstrate detection of less than $10^{13}$ $^{129}$Xe atoms whose NMR signal is enhanced by a factor of 540 due to Fermi-contact interaction with K atoms. This technique allows detection of less than $10^{9}$ $^{129}$Xe spins in a flowing system suitable for remote NMR applications.

  1. NMR with Hyperpolarised Protons in Metals

    Energy Technology Data Exchange (ETDEWEB)

    Engelbertz, A., E-mail: engelbert@iskp.uni-bonn.de; Anbalagan, P.; Bommas, C.; Eversheim, P.-D.; Hartman, D. T.; Maier, K. [University of Bonn, Helmholtz- Institut fuer Strahlen und Kernphysik (Germany)

    2004-12-15

    Proton pulse NMR, established as a versatile method in Solid State Physics, Chemistry, Biology and Medical Science, requires on the order of 10{sup 18} nuclei to detect an electromagnetic signal in a free induction decay (FID). The main cause for this small sensitivity is the low polarisation in the order of a few ppm due to the Boltzmann distribution in the magnetic field. Thus, NMR experiments on hydrogen are limited to metals with extremely high hydrogen solubility like Pd near room temperature. Using a polarised proton beam, a NMR signal is possible with as few as 10{sup 13} implanted nuclei. For the first time spin-spin and spin-lattice relaxation times were measured in Au and W with this technique at the Bonn cyclotron.

  2. Entanglement witness derived from NMR superdense coding

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Robabeh [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Takeda, Kazuyuki [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Ozawa, Masanao [Graduate School of Information Sciences, Tohoku University, Aoba-ku, Sendai 980-8579 (Japan); Kitagawa, Masahiro [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2006-03-03

    It is shown that superdense coding (SDC) experiments by means of nuclear magnetic resonance (NMR) can show non-classical efficiency gain over classical communication only for nuclear spin polarization beyond a certain threshold, and this threshold coincides with that for non-separability of the density matrix. It is also claimed that transfer of two-bit information mediated by a single qubit in the previous NMR SDC experiments with low nuclear spin polarization is not ascribed to the non-classical effect induced by entanglement, but merely to a statistical effect in an ensemble system having a large number of molecules. Towards experimental detection of entanglement, a new class of entanglement witnesses is proposed, which is based on the measurement of nuclear spin magnetizations in the Bell basis and is suitable for actual NMR experiments.

  3. NMR Spectroscopy: Processing Strategies (by Peter Bigler)

    Science.gov (United States)

    Mills, Nancy S.

    1998-06-01

    Peter Bigler. VCH: New York, 1997. 249 pp. ISBN 3-527-28812-0. $99.00. This book, part of a four-volume series planned to deal with all aspects of a standard NMR experiment, is almost the exact book I have been hoping to find. My department has acquired, as have hundreds of other undergraduate institutions, high-field NMR instrumentation and the capability of doing extremely sophisticated experiments. However, the training is often a one- or two-day experience in which the material retained by the faculty trained is garbled and filled with holes, not unlike the information our students seem to retain. This text, and the accompanying exercises based on data contained on a CD-ROM, goes a long way to fill in the gaps and clarify misunderstandings about NMR processing.

  4. 1H NMR spectra dataset and solid-state NMR data of cowpea (Vigna unguiculata)

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  5. Instrumentation in NMR/NMR imaging; Instrumentation en RMN/IRM

    Energy Technology Data Exchange (ETDEWEB)

    Favre, B.; Desgoutte, P.; Marguet, Ch. [Universite Claude Bernard, Lab. de Resonance Magnetique Nuleaire, 69 - Villeurbanne (France)

    1999-07-01

    Nuclear Magnetic Resonance (NMR) is largely used in medical imaging and in spectroscopy for the chemistry. The equipment is complex and explosive, and is not easily accessible for teaching. The didactic machine presented here allows, thanks to an extreme simplification, to approach essential notions of NMR with a cost and a space-factor reduced. It allows to visualize the phenomenon of NMR, to illustrate its main applications, and to measure main parameters concerning the magnetic field or the sample. In addition, it can be used to study signal acquisition and processing, fundamental digital and analog electronic circuits, programming... (authors)

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

    Science.gov (United States)

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

    2017-04-01

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

  7. Applied NMR spectroscopy for chemists and life scientists

    CERN Document Server

    Zerbe, Oliver

    2013-01-01

    From complex structure elucidation to biomolecular interactions - this applicationoriented textbook covers both theory and practice of modern NMR applications. Part one sets the stage with a general description of NMR introducing important parameters such as the chemical shift and scalar or dipolar couplings. Part two describes the theory behind NMR, providing a profound understanding of the involved spin physics, deliberately kept shorter than in other NMR textbooks, and without a rigorous mathematical treatment of all the physico-chemical computations. Part three discusses technical and practical aspects of how to use NMR. Important phenomena such as relaxation, exchange, or the nuclear Overhauser effects and the methods of modern NMR spectroscopy including multidimensional experiments, solid state NMR, and the measurement of molecular interactions are the subject of part four. The final part explains the use of NMR for the structure determination of selected classes of complex biomolecules, from steroids t...

  8. Quantification of complex mixtures by NMR

    NARCIS (Netherlands)

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

    2013-01-01

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

  9. Bench-top NMR-food

    NARCIS (Netherlands)

    Voda, M.A.; Duynhoven, Van J.

    2016-01-01

    In food research and development, relaxometric and diffusometric benchtop NMR methods have been used to obtain quantitative phase compositional and food microstructural parameters in a routine manner. The most commonly used applications are assessment of solid fat content, and water and oil dropl

  10. NMR and Mushrooms : imaging post harvest senescence

    NARCIS (Netherlands)

    Donker, H.C.W.

    1999-01-01

    The objective of the study described in this thesis was to explore the potentials of NMR for the study of water relations in harvested mushrooms ( Agaricus bisporus ). Since harvested mushrooms tend to continue their growth after harvest, their morphogenesis is heavily influenced by the external cli

  11. NMR characterization of polymers: Review and update

    Science.gov (United States)

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

  12. NMR analog of the quantum disentanglement eraser.

    Science.gov (United States)

    Teklemariam, G; Fortunato, E M; Pravia, M A; Havel, T F; Cory, D G

    2001-06-25

    We report the implementation of a three-spin quantum disentanglement eraser on a liquid-state NMR quantum information processor. A key feature of this experiment was its use of pulsed magnetic field gradients to mimic projective measurements. This ability is an important step towards the development of an experimentally controllable system which can simulate any quantum dynamics, both coherent and decoherent.

  13. Structural Studies of Biological Solids Using NMR

    Science.gov (United States)

    Ramamoorthy, Ayyalusamy

    2011-03-01

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

  14. 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.

  15. NMR of porous bio-systems

    NARCIS (Netherlands)

    Snaar, J.E.M.

    2002-01-01

    The structure and dynamics of water diffusion and -transport at a microscale in heterogeneous porous media have been investigated using various 1H NMR techniques. In particular in biological porous media the dynamics are usually very complex

  16. CASD-NMR: critical assessment of automated structure determination by NMR

    NARCIS (Netherlands)

    Rosato, A.; van der Schot, G.; Bonvin, A.M.J.J.

    2009-01-01

    NMR spectroscopy is currently the only technique for determining the solution structure of biological macromolecules. This typically requires both the assignment of resonances and a labor-intensive analysis of multidimensional nuclear Overhauser effect spectroscopy (NOESY) spectra, in which peaks

  17. A mobile one-sided NMR sensor with a homogeneous magnetic field: the NMR-MOLE.

    Science.gov (United States)

    Manz, B; Coy, A; Dykstra, R; Eccles, C D; Hunter, M W; Parkinson, B J; Callaghan, P T

    2006-11-01

    A new portable NMR sensor with a novel one-sided access magnet design, termed NMR-MOLE (MObile Lateral Explorer), has been characterised in terms of sensitivity and depth penetration. The magnet has been designed to be portable and create a volume with a relatively homogeneous magnetic field, 15,000 ppm over a region from 4 to 16 mm away from the probe, with maximum sensitivity at a depth of 10 mm. The proton NMR frequency is 3.3 MHz. We have demonstrated that with this approach a highly sensitive, portable, unilateral NMR sensor can be built. Such a design is especially suited for the characterisation of liquids in situations where unilateral or portable access is required.

  18. Progress in NMR Applications to Well Logging and Formation Evaluation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Since its discovery in 1946, NMR has become a valuable tool in physics, chemistry, biology, and medicine. With the invention of NMR logging tools that take the medical MRI or laboratory NMR equipment and turn it inside-out, the application of sophisticated laboratory techniques to determine formation properties in situ is now available. The capability has opened a new era in formation evaluation just as the introduction of NMR has revolutionized the other scientific areas.

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

    OpenAIRE

    Queiroz Júnior,Luiz H. K.; Antonio G. Ferreira; Patrick Giraudeau

    2013-01-01

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Schot, Gijs van der [Uppsala University, Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology (Sweden); Bonvin, Alexandre M. J. J., E-mail: a.m.j.j.bonvin@uu.nl [Utrecht University, Faculty of Science – Chemistry, Bijvoet Center for Biomolecular Research (Netherlands)

    2015-08-15

    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.

  1. Several Applications of NMR in Organic Chemistry Research

    Institute of Scientific and Technical Information of China (English)

    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.

  2. Several Applications of NMR in Organic Chemistry Research

    Institute of Scientific and Technical Information of China (English)

    CUI; yuxin; 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.  ……

  3. Polymeric proanthocyanidins 13C NMR studies of procyanidins

    Science.gov (United States)

    Lawrence J. Porter; Roger H. Newman; Lai Yeap Foo; Herbert Wong; Richard W. Hemingway

    1982-01-01

    Proanthocyanidin polymers have been shown to consist entirely of flavan-3-ol units by a combination of techniques including 13C n.m.r. spectroscopy. The 13C n.m.r. spectra of the polymers and related molecules are now considered in more detail. Prior to this study UC n.m.r. data has been published of procyanidins and...

  4. Study of NMR porosity for terrestrial formation in China

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaowen; XIAO Lizhi; XIE Ranhong; ZHANG Yuanzhong

    2006-01-01

    NMR logging is an effective method for porosity measurement. NMR-derived porosity only comes from the pore fluid and is, in principle, not affected by rock matrix. However, it is found that the difference between NMR-derived and conventional log-derived porosities is often between 2 to 6 pu, which is unacceptable, in terrestrial formation in China. In the paper, the theory of NMR porosity was reviewed. The influence factors on NMR porosity error were analyzed based on NMR core measurements. More than 30 core samples with a wide range of porosities including sandstone, limestone and artificial ceramic were chosen for the conventional and NMR porosity measurements. The current NMR data acquisition method was studied based on laboratory NMR core measurements and found to be not good for terrestrial formation. A new NMR data acquisition method suiting for terrestrial formation in China was proposed and much improved the accuracy of NMR porosity measurement. It is suggested that the analysis of core samples from different regions should be carried out before logging in order to obtain accurate NMR porosity.

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

    Science.gov (United States)

    Takeda, Kazuyuki

    2008-06-01

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

  6. Continuous Flow 1H and 13C NMR Spectroscopy in Microfluidic Stripline NMR Chips

    Science.gov (United States)

    2017-01-01

    Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline’s favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional 1H, 13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds. PMID:28194934

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

    Science.gov (United States)

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

    2004-02-01

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

  8. NMR CHARACTERIZATIONS OF PROPERTIES OF HETEROGENEOUS MEDIA

    Energy Technology Data Exchange (ETDEWEB)

    C.T. Philip Chang; Changho Choi; Jeromy T. Hollenshead; Rudi Michalak; Jack Phan; Ramon Saavedra; John C. Slattery; Jinsoo Uh; Randi Valestrand; A. Ted Watson; Song Xue

    2005-01-01

    A critical and long-standing need within the petroleum industry is the specification of suitable petrophysical properties for mathematical simulation of fluid flow in petroleum reservoirs (i.e., reservoir characterization). The development of accurate reservoir characterizations is extremely challenging. Property variations may be described on many scales, and the information available from measurements reflect different scales. In fact, experiments on laboratory core samples, well-log data, well-test data, and reservoir-production data all represent information potentially valuable to reservoir characterization, yet they all reflect information about spatial variations of properties at different scales. Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) provide enormous potential for developing new descriptions and understandings of heterogeneous media. NMR has the rare capability to probe permeable media non-invasively, with spatial resolution, and it provides unique information about molecular motions and interactions that are sensitive to morphology. NMR well-logging provides the best opportunity ever to resolve permeability distributions within petroleum reservoirs. We develop MRI methods to determine, for the first time, spatially resolved distributions of porosity and permeability within permeable media samples that approach the intrinsic scale: the finest resolution of these macroscopic properties possible. To our knowledge, this is the first time that the permeability is actually resolved at a scale smaller than the sample. In order to do this, we have developed a robust method to determine of relaxation distributions from NMR experiments and a novel implementation and analysis of MRI experiments to determine the amount of fluid corresponding to imaging regions, which are in turn used to determine porosity and saturation distributions. We have developed a novel MRI experiment to determine velocity distributions within flowing experiments, and

  9. Solid state NMR of biopolymers and synthetic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Jelinski, Lynn W. [Cornell Univ., Geneva, NY (United States)

    1995-12-31

    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 {sup 13} C and {sup 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) 11 refs., 5 figs., 3 tabs.

  10. Direct 13C NMR Detection in HPLC Hyphenation Mode

    DEFF Research Database (Denmark)

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

    2012-01-01

    Solid phase extraction (SPE) was introduced as a crucial step in the HPLC-SPE-NMR technique to enable online analyte enrichment from which proton-detected NMR experiments on submicrogram amounts from complex mixtures were possible. However, the significance of direct-detected (13)C NMR experiments...... application of HPLC-SPE-NMR analysis using direct-detected (13)C NMR spectra. HPLC column loading, accumulative SPE trappings, and the effect of different elution solvents were evaluated and optimized. A column loading of approximately 600 mug of a prefractionated triterpenoid mixture, six trappings...

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

    Science.gov (United States)

    Schreckenbach, Georg

    2002-12-16

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

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

    Science.gov (United States)

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

    2011-08-07

    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.

  13. Solid-state NMR basic principles and practice

    CERN Document Server

    Apperley, David C; Hodgkinson, Paul

    2012-01-01

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

  14. Solid-state NMR basic principles and practice

    CERN Document Server

    Apperley, David C; Hodgkinson, Paul

    2014-01-01

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

  15. Fully automated system for pulsed NMR measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cantor, David Milton

    1977-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. NMR and the local structure of relaxors

    Directory of Open Access Journals (Sweden)

    Blinc R.

    2002-01-01

    Full Text Available The relaxor transition in cubic perovskite relaxors (PMN, PSN and PST and tungsten bronze relaxor (SBN has been studied by NMR. The observed spectra are composed of a narrow -1/2 « 1/2 central transition superimposed on a broad background due to satellite transitions. The chemical heterogeneity, responsible for relaxor properties, is reflected here in the structure of the central transition part. The latter is composed of two components, one due to ordered and the other due to disordered regions. Despite of the fact that the macroscopic symmetry does not change when relaxor transition occurs, a non-zero quadruple coupling constant determined from NMR clearly demonstrates the broken local symmetry.

  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. Zero-field NMR and NQR spectrometer

    Science.gov (United States)

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

    1986-03-01

    In comparison to high-field NMR, zero-field techniques offer advantages in terms of spectral interpretability in studies of polycrystalline or amorphous solids. This article describes a technique and apparatus for time-domain measurements of nuclear magnetism in the absence of applied fields (Fourier transform zero-field NMR and NQR). Magnetic field cycling and high field detection are employed to enhance sensitivity. The field cycling is accomplished with an air-driven shuttle system which moves the sample between regions of high and low magnetic field, in combination with switchable electromagnets in the low-field region. Sudden field steps or pulses are used to initiate coherent nuclear spin evolution in zero field and to monitor such evolution as a function of time. Experimental results are shown and analyzed. Possible variations on the basic method are described and their relative advantages are discussed.

  2. 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.

  3. 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.

  4. MEASURING VARIABILITY SOURCES IN NMR METABOLOMIC STUDIES

    OpenAIRE

    Rozet, Eric; de Tullio, Pascal; Hubert, Philippe; Govaerts., B.

    2013-01-01

    Due to the huge amount of information available in NMR spectra obtained from the analysis of metabolomic experiments, multivariate analysis such as Principal Component Analysis (PCA) are required to understand the influence of treatments over the metabolites [1]. However, many experiments in metabolomics studies have more complexes variability structures than simply comparing several treatments: they may include time effects, biological effects such as diet or hormonal status, and other bloc...

  5. 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.

  6. NMR Structural Studies on Alamethicin Dimers

    Institute of Scientific and Technical Information of China (English)

    李星

    2003-01-01

    15N labeled alamethicin dimer was synthesized. The structure and dynamics of alamethicin dimers were studied with nuclear magnetic resonance (NMR) spectroscopy. The data from 15N-labeled alamethicin dimer suggest little differences in conformation between the dimer and monomer in the Aib1-Pro14 region. Significant difference in the conformation of the C-terminus are manifest in the NH chemical shifts in the Val15-Pho20 region.

  7. Automatic maximum entropy spectral reconstruction in NMR.

    Science.gov (United States)

    Mobli, Mehdi; Maciejewski, Mark W; Gryk, Michael R; Hoch, Jeffrey C

    2007-10-01

    Developments in superconducting magnets, cryogenic probes, isotope labeling strategies, and sophisticated pulse sequences together have enabled the application, in principle, of high-resolution NMR spectroscopy to biomolecular systems approaching 1 megadalton. In practice, however, conventional approaches to NMR that utilize the fast Fourier transform, which require data collected at uniform time intervals, result in prohibitively lengthy data collection times in order to achieve the full resolution afforded by high field magnets. A variety of approaches that involve nonuniform sampling have been proposed, each utilizing a non-Fourier method of spectrum analysis. A very general non-Fourier method that is capable of utilizing data collected using any of the proposed nonuniform sampling strategies is maximum entropy reconstruction. A limiting factor in the adoption of maximum entropy reconstruction in NMR has been the need to specify non-intuitive parameters. Here we describe a fully automated system for maximum entropy reconstruction that requires no user-specified parameters. A web-accessible script generator provides the user interface to the system.

  8. 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.

  9. 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...

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

    Science.gov (United States)

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

    2012-10-01

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

  11. Protein NMR structures refined without NOE data.

    Science.gov (United States)

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

    2014-01-01

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

  12. In-cell NMR: a topical review

    Directory of Open Access Journals (Sweden)

    Enrico Luchinat

    2017-03-01

    Full Text Available Classical structural biology approaches allow structural characterization of biological macromolecules in vitro, far from their physiological context. Nowadays, thanks to the wealth of structural data available and to technological and methodological advances, the interest of the research community is gradually shifting from pure structural determination towards the study of functional aspects of biomolecules. Therefore, a cellular structural approach is ideally needed to characterize biological molecules, such as proteins, in their native cellular environment and the functional processes that they are involved in. In-cell NMR is a new application of high-resolution nuclear magnetic resonance spectroscopy that allows structural and dynamical features of proteins and other macromolecules to be analyzed directly in living cells. Owing to its challenging nature, this methodology has shown slow, but steady, development over the past 15 years. To date, several in-cell NMR approaches have been successfully applied to both bacterial and eukaryotic cells, including several human cell lines, and important structural and functional aspects have been elucidated. In this topical review, the major advances of in-cell NMR are summarized, with a special focus on recent developments in eukaryotic and mammalian cells.

  13. 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...

  14. Phosphorus NMR of isolated perfused morris hepatomas

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R.A.; Meyer, R.A.; Brown, T.R.; Sauer, L.A.

    1986-03-05

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

  15. NMR Studies of Cartilage Dynamics, Diffusion, Degradation

    Science.gov (United States)

    Huster, Daniel; Schiller, Jurgen; Naji, Lama; Kaufmann Jorn; Arnold, Klaus

    An increasing number of people is suffering from rheumatic diseases, and, therefore, methods of early diagnosis of joint degeneration are urgently required. For their establishment, however, an improved knowledge about the molecular organisation of cartilage would be helpful. Cartilage consists of three main components: Water, collagen and chondroitin sulfate (CS) that is (together with further polysaccharides and proteins) a major constituent of the proteoglycans of cartilage. 1H and 13C MAS (magic-angle spinning) NMR (nuclear magnetic resonance) opened new perspectives for the study of the macromolecular components in cartilage. We have primarily studied the mobilities of CS and collagen in bovine nasal and pig articular cartilage (that differ significantly in their collagen/polysaccharide content) by measuring 13C NMR relaxation times as well as the corresponding 13C CP (cross polarisation) MAS NMR spectra. These data clearly indicate that the mobility of cartilage macromolecules is broadly distributed from almost completely rigid (collagen) to highly mobile (polysaccharides), which lends cartilage its mechanical strength and shock-absorbing properties.

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

    Science.gov (United States)

    Skinner, Simon P; Fogh, Rasmus H; Boucher, Wayne; Ragan, Timothy J; Mureddu, Luca G; Vuister, Geerten W

    2016-10-01

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

  17. 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.

  18. Direct Speciation of Phosphorus in Alum-Amended Poultry Litter: Solid-State 31P NMR Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Hunger, Stefan; Cho, Herman M.; Sims, James T.; Sparks, Donald L.

    2004-02-01

    Amending poultry litter (PL) with aluminum sulfate (alum) has proven to be effective in reducing water-soluble phosphorus (P) in the litter and in runoff from fields that have received PL applications; it has therefore been suggested as a best management practice. Although its effectiveness has been demonstrated on a macroscopic scale in the field, little is known about P speciation in either alumamended or unamended litter. This knowledge is important for the evaluation of the long-term stability and bioavailability of P, which is a necessary prerequisite for the assessment of the sustainability of intensive poultry operations. Both solid state MAS and CP-MAS {sup 31}P NMR as well as {sup 31}P({sup 27}Al) TRAPDOR were used to investigate P speciation in alumamended and unamended PL. The results indicate the presence of a complex mixture of organic and inorganic orthophosphate phases. A calcium phosphate phase, probably a surface precipitate on calcium carbonate, could be identified in both unamended and alum-amended PL, as well as physically bound HPO{sub 4}{sup 2-}. Phosphate associated with Al was found in the alum-amended PL, most probably a mixture of a poorly ordered wavellite and phosphate surface complexes on aluminum hydroxide that had been formed by the hydrolysis of alum. However, a complex mixture of organic and inorganic phosphate species could not be resolved. Phosphate associated with Al comprised on average 40{+-}14% of the total P in alum-amended PL, whereas calcium phosphate phases comprised on average 7{+-}4% in the alum-amended PL and 14{+-}5% in the unamended PL.

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Bingol, Kerem; Brüschweiler, Rafael

    2017-02-01

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

  2. Modern solid-state NMR on functional polymers; Moderne Festkoerper-NMR an Funktionspolymeren

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M.

    2004-07-01

    In this thesis the microscopic structures of natural caoutchouc, on silicic acid plugged polydimethylsiloxane (PDMS), and polyamide-clay-nanocomposite are studied. For natural caoutchouc it is shown how the network density can be characterized by the study of the dipole-dipole couplings between protons and carbon by means of the heteronuclear double-quantum NMR method and further double-resonance experiments. In PDMS homo- and heteronuclear multi-quantum NMR, spin-diffusion, relaxometry, and double-resonance experiments are used for the study of the dependence of the molecular motion on external influences. Finally the structural change of polyamides by addition of clay particles is studied.

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

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

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

  4. 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.

  5. 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.

  6. High resolution MAS-NMR in combinatorial chemistry.

    Science.gov (United States)

    Shapiro, M J; Gounarides, J S

    High-resolution magic angle spinning (hr-MAS) NMR is a powerful tool for characterizing organic reactions on solid support. Because magic angle spinning reduces the line-broadening due to dipolar coupling and variations in bulk magnetic susceptibility, line widths approaching those obtained in solution-phase NMR can be obtained. The magic angle spinning method is amenable for use in conjunction with a variety of NMR-pulse sequences, making it possible to perform full-structure determinations and conformational analysis on compounds attached to a polymer support. Diffusion-weighted MAS-NMR methods such as SPEEDY (Spin-Echo-Enhanced Diffusion-Filtered Spectroscopy) can be used to remove unwanted signals from the solvent, residual reactants, and the polymer support from the MAS-NMR spectrum, leaving only those signals arising from the resin-bound product. This review will present the applications of high-resolution magic angle spinning NMR for use in combinatorial chemistry research.

  7. 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 image analysis were carried out on sixteen greensand samples from two formations in the Nini field of the North Sea. Hermod Formation is weakly cemented, whereas Ty Formation is characterized by microcrystalline quartz cement. The surface area measured by the BET method and the NMR derived surface...... with macro-pores. Permeability may be predicted from NMR by using Kozeny's equation when surface relaxivity is known. Capillary pressure drainage curves may be predicted from NMR T2 distribution when pore size distribution within a sample is homogeneous....

  8. (S)Pinning down protein interactions by NMR

    DEFF Research Database (Denmark)

    Teilum, Kaare; Kunze, Micha Ben Achim; Erlendsson, Simon

    2017-01-01

    all types of protein reactions, which can span orders of magnitudes in affinities, reaction rates and lifetimes of states. As the more versatile technique, solution NMR spectroscopy offers a remarkable catalogue of methods that can be successfully applied to the quantitative as well as qualitative...... descriptions of protein interactions. In this review we provide an easy-access approach to NMR for the non-NMR specialist and describe how and when solution state NMR spectroscopy is the method of choice for addressing protein ligand interaction. We describe very briefly the theoretical background...... and illustrate simple protein-ligand interactions and as well as typical strategies for measuring binding constants using NMR spectroscopy. Finally, this review provides examples of caveats of the method as well as the options to improve the outcome of an NMR analysis of a protein interaction reaction...

  9. NMR Based Quantum Information Processing Achievements and Prospects

    CERN Document Server

    Cory, D G; Knill, E H; Viola, L; Havel, T F; Boulant, N; Boutis, G; Fortunato, E M; Lloyd, S; Martínez, R; Negrevergne, C; Pravia, M A; Sharf, Y; Teklemariam, G; Weinstein, Yu S; Zurek, W H

    2000-01-01

    Nuclear magnetic resonance (NMR) provides an experimental setting to explore physical implementations of quantum information processing (QIP). Here we introduce the basic background for understanding applications of NMR to QIP and explain their current successes, limitations and potential. NMR spectroscopy is well known for its wealth of diverse coherent manipulations of spin dynamics. Ideas and instrumentation from liquid state NMR spectroscopy have been used to experiment with QIP. This approach has carried the field to a complexity of about 10 qubits, a small number for quantum computation but large enough for observing and better understanding the complexity of the quantum world. While liquid state NMR is the only present-day technology about to reach this number of qubits, further increases in complexity will require new methods. We sketch one direction leading towards a scalable quantum computer using spin 1/2 particles. The next step of which is a solid state NMR-based QIP capable of reaching 10-30 qub...

  10. Lithium Polymer Electrolytes and Solid State NMR

    Science.gov (United States)

    Berkeley, Emily R.

    2004-01-01

    Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for

  11. NMR study of magnetism and superparamagnetism

    Science.gov (United States)

    Yuan, Shaojie

    The research described in this dissertation is concerned with two different types of magnetic materials. Both types of systems involve competing interactions between transition metal ions. New approaches involving magnetic resonance in the large hyperfine fields at nuclear sites have been developed. The interactions responsible for the properties that have been investigated in the materials studied are geometric frustration in an insulator and ferromagnetic and antiferromagnetic interactions in a metal alloy. Further details are given below. The extended kagome frustrated system YBaCo4O7 has 2D kagome and triangular lattices of Co ions stacked along the c-axis. Antiferromagnetic (AF) ordering accompanied by a structural transition has been reported in the literature. From a zero field (ZF) NMR single crystal rotation experiment, we have obtained the Co spin configurations for both the kagome and triangular layers. A 'spin-flop' configuration between the spins on the kagome layer and the spins on the triangular layer is indicated by our results. Our NMR findings are compared with neutron scattering results for this intriguing frustrated AF spin system. The non-stoichiometric oxygenated sister compound YBaCo4O7.1 has application potential for oxygen storage. While, its' magnetic properties are quite different from those of the stoichiometric compound, in spite of their similar structures of alternating kagome and triangular Co layers. Various techniques, including ZF NMR have been used to investigate the spin dynamics and spin configuration in a single crystal of YBaCo4O7.1. A magnetic transition at 80 K is observed, which is interpreted as the freezing out of spins in the triangular layers. At low temperatures (below 50 K), the spin dynamics persists and a fraction of spins in the kagome layers form a viscous spin liquid. Below 10 K, a glass-like spin structure forms and a large distribution of spin correlation times are suggested by nuclear spin lattice relaxation

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

    Energy Technology Data Exchange (ETDEWEB)

    Hirasaki, George J.; Mohanty, Kishore K.

    2003-02-10

    The objective of this project was to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. The advances made in the understanding of NMR fluid properties are summarized in a chapter written for an AAPG book on NMR well logging. This includes live oils, viscous oils, natural gas mixtures, and the relation between relaxation time and diffusivity.

  13. Complete NMR analysis of oxytocin in phosphate buffer.

    Science.gov (United States)

    Ohno, Akiko; Kawasaki, Nana; Fukuhara, Kiyoshi; Okuda, Haruhiro; Yamaguchi, Teruhide

    2010-02-01

    Complete NMR analysis of oxytocin (OXT) in phosphate buffer was elucidated by one-dimensional (1D)- and two-dimensional (2D)-NMR techniques, which involve the assignment of peptide amide NH protons and carbamoyl NH(2) protons. The (1)H-(15)N correlation of seven amide NH protons and three carbamoyl NH(2) protons were also shown by HSQC NMR of OXT without (15)N enrichment.

  14. 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.

  15. Direct 13C NMR Detection in HPLC Hyphenation Mode

    DEFF Research Database (Denmark)

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

    2012-01-01

    Solid phase extraction (SPE) was introduced as a crucial step in the HPLC-SPE-NMR technique to enable online analyte enrichment from which proton-detected NMR experiments on submicrogram amounts from complex mixtures were possible. However, the significance of direct-detected (13)C NMR experiments......, and an acquisition time of 13 h resulted in spectra with adequate signal-to-noise ratios to detect all C-13 signals....

  16. NMR Characterizations of Properties of Heterogeneous Media

    Energy Technology Data Exchange (ETDEWEB)

    Uh, Jinsoo; Phan, Jack; Xue, Dong; Watson, A. Ted

    2003-01-28

    The overall goal of this project was to develop reliable methods for resolving macroscopic properties important for describing the flow of one or more fluid phases in reservoirs from formation measurements. During this reporting period, the determination of surface relaxivity from NMR data was investigated. A new method for determining the surface relaxivity from measured data was developed and tested with data obtained from an Exxon sample. The new method avoids the use of a certain mathematical short-time approximation in the data analysis, which has been shown to be unsuitable.

  17. Quenched Hydrogen Exchange NMR of Amyloid Fibrils.

    Science.gov (United States)

    Alexandrescu, Andrei T

    2016-01-01

    Amyloid fibrils are associated with a number of human diseases. These aggregatively misfolded intermolecular β-sheet assemblies constitute some of the most challenging targets in structural biology because to their complexity, size, and insolubility. Here, protocols and controls are described for experiments designed to study hydrogen-bonding in amyloid fibrils indirectly, by transferring information about amide proton occupancy in the fibrils to the dimethyl sulfoxide-denatured state. Since the denatured state is amenable to solution NMR spectroscopy, the method can provide residue-level-resolution data on hydrogen exchange for the monomers that make up the fibrils.

  18. NMR-tomography of the heart

    Energy Technology Data Exchange (ETDEWEB)

    Weikl, A.; Bachmann, K.

    1987-04-03

    The NMR-tomography as a non-invasive imaging process is examined regarding to the value to answer clinical issues. This method allows an evaluation of qualitative, quantitative, morphological and functional parameters. The diagnostic use on the heart shows early myocardial changes, thrombosis, changes in the dynamics of the left ventricle (EDV, ESV, EF), the quantitative wall movement and the blood flow in a shunt defect. The placed value of echocardiography, myocardial scintigraphy and coronary angiography in the diagnosis of acquired valvular heart disease, myocardial perfusion and coronary heart disease is not lowered by the above mentioned method.

  19. Dynamic NMR cardiac imaging in a piglet

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-12-01

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

  20. 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.

  1. Touch NMR: An NMR Data Processing Application for the iPad

    Science.gov (United States)

    Li, Qiyue; Chen, Zhiwei; Yan, Zhiping; Wang, Cheng; Chen, Zhong

    2014-01-01

    Nuclear magnetic resonance (NMR) spectroscopy has become one of the most powerful technologies to aid research in numerous scientific disciplines. With the development of consumer electronics, mobile devices have played increasingly important roles in our daily life. However, there is currently no application available for mobile devices able to…

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

    DEFF Research Database (Denmark)

    Li, Xiaozhou; Tapmeyer, Lukas; Bolte, Michael

    2016-01-01

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

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

    NARCIS (Netherlands)

    Mierlo, van C.

    1990-01-01

    1H NMR techniques have been applied for a thorough study of the uncrystallizable Megasphaera elsdenii flavodoxin in its three redox states. The aim of the research project described in this thesis was to obtain answers regarding questions concerni

  4. 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.

  5. 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)

  6. 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.

  7. An NMR study of adsorbed helium films

    Science.gov (United States)

    Kent, Anthony Joseph

    The properties of sub-monolayer Helium-3 films adsorbed on two totally different but planar substrates, Mylar† film and exfoliated graphite have been studied using NMR. The nuclear magnetic relaxation times T1 and T 2 have been measured as functions of fractional monolayer completion, temperature, substrate plane orientation and Larmor frequency using a specially designed and constructed NMR spectrometer system. The results obtained with a Mylar film substrate are consistent3with the formation of patches of solid 3He at regions of preferential adsorption on the substrate. Measurements of T2 m very low coverage 3He films on exfoliated graphite also indicate that the adsorbate forms areas of relatively high density solid, in agreement with the thermodynamic analysis of Elgin and Goodstein. Finally, detailed measurements of T2 as a function of all of the above parameters at low areal densities will help us to characterise the relaxation processes for the fluid phase of 33He on exfoliated graphite. †Mylar is the tradename of poly(ethelene-terephthalate) film, marketed by Du Pont.

  8. NMR probe for dynamic-angle spinning

    Science.gov (United States)

    Mueller, K. T.; Chingas, G. C.; Pines, A.

    1991-06-01

    We describe the design of a probe for dynamic-angle spinning (DAS) NMR experiments, comprised of a spinning cylindrical sample holder whose axis may be reoriented rapidly between discrete directions within the bore of a superconducting magnet. This allows the refocusing of nuclear spin magnetization that evolves under anisotropic interactions such as chemical shift anisotropy and quadrupolar coupling, providing high resolution NMR spectra for quadrupolar nuclei in solid materials. The probe includes an axial air delivery system to bearing and drive jets which support and spin a rotor containing the sample. Axis reorientation is accomplished with a pulley attached to the probehead and coupled to a stepping motor outside of the magnet. The choice of motor and gear ratio is based on an analysis of the moments of inertia of the motor and load, the desired angular resolution, and simplicity of design. Control of angular accuracy and precision are discussed, as well as the efficiency of radiofrequency irradiation and detection. High resolution DAS spectra of oxygen-17 and aluminum-27 nuclei in polycrystalline minerals illustrate the experimental capabilities.

  9. Probe for high resolution NMR with sample reorientation

    Science.gov (United States)

    Pines, Alexander; Samoson, Ago

    1990-01-01

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

  10. Bringing NMR and IR Spectroscopy to High Schools

    Science.gov (United States)

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

    2017-01-01

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

  11. 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.

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

    CERN Document Server

    Fleming, George T

    2004-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Kishore K. Mohanty

    2005-09-05

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

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

    Science.gov (United States)

    The 1H NMR methodology used in the study of genetically modified (GM) foodstuff is discussed. The study of transgenic lettuce (Lactuca sativa cv "Luxor") over-expressing the KNAT1 gene from Arabidopsis is presented as a novel study-case. The 1H NMR metabolic profiling was carried out. Twenty-two wat...

  15. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang; Feng; Wu; Chengtai; 等

    2003-01-01

    The NMR methods (including 1H NMR, variable temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  16. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang Feng; Wu Xiao-jun; Wu Cheng-tai

    2003-01-01

    The NMR methods (including 1H NMR, vari-able temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  17. Bringing NMR and IR Spectroscopy to High Schools

    Science.gov (United States)

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

    2017-01-01

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

  18. Advanced solid-state NMR spectroscopy of natural organic matter

    Science.gov (United States)

    Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially the systematic approach to NOM characterization, and their ...

  19. Characterizing RNA ensembles from NMR data with kinematic models

    DEFF Research Database (Denmark)

    Fonseca, Rasmus; Pachov, Dimitar V.; Bernauer, Julie;

    2014-01-01

    the conformational landscapes of 3D RNA encoded by NMR proton chemical shifts. KGSrna resolves motionally averaged NMR data into structural contributions; when coupled with residual dipolar coupling data, a KGSrna ensemble revealed a previously uncharacterized transient excited state of the HIV-1 trans...

  20. Realization of quantum discrete Fourier transform with NMR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The pulse sequences of the logic operations used in quantum discrete Fourier transform are designed for the experiment of nuclear magnetic resonance(NMR), and 2-qubit discrete Fourier transforms are implemented experimentally with NMR. The experimental errors are examined and methods for reducing the errors are proposed.

  1. Development of β-NMR and β-NQR

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dong-Mei(周冬梅); M. Mihara; M. Fukuda; K. Matsuta; T. Minamisono; ZHU Sheng-Yun(朱升云); ZHENG Yong-Nan(郑永男); ZHU Jia-Zheng(朱佳政); XU Yong-Jun(徐勇军); DU En-Peng(杜恩鹏); WANG Zhi-Qiang(王志强); Luo Hai-Long(骆海龙); YUAN Da-Qing(袁大庆); RONG Chao-Fan(容超凡)

    2003-01-01

    The β-NMR (nuclear magnetic resonance) and β-NQR (nuclear quadrupole resonance) technique and its experimental set-up have been developed for the first time in China. The lifetime, magnetic moment and spin polarization of 12B were determined. The experimental results show the reliability of this newly developed β-NMR andβ-NQR set-up.

  2. SPE-NMR metabolite sub-profiling of urine

    NARCIS (Netherlands)

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

    2012-01-01

    NMR-based metabolite profiling of urine is a fast and reproducible method for detection of numerous metabolites with diverse chemical properties. However, signal overlap in the (1)H NMR profiles of human urine may hamper quantification and identification of metabolites. Therefore, a new method has b

  3. SPE-NMR metabolite sub-profiling of urine

    NARCIS (Netherlands)

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

    2012-01-01

    NMR-based metabolite profiling of urine is a fast and reproducible method for detection of numerous metabolites with diverse chemical properties. However, signal overlap in the (1)H NMR profiles of human urine may hamper quantification and identification of metabolites. Therefore, a new method has

  4. Achieving High Accuracy in Calculations of NMR Parameters

    DEFF Research Database (Denmark)

    Faber, Rasmus

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most commonly used tools in the analysis of chemical structures. In NMR the nuclear spin-states of a molecule are probed, yielding information about the chemical environment of each nucleus. As the spins of nearby nuclei interact, concre...

  5. 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.

  6. Functional groups identified by solid state 13C NMR spectroscopy

    Science.gov (United States)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  7. Advanced solid-state NMR spectroscopy of natural organic matter.

    Science.gov (United States)

    Mao, Jingdong; Cao, Xiaoyan; Olk, Dan C; Chu, Wenying; Schmidt-Rohr, Klaus

    2017-05-01

    Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially a systematic approach to NOM characterization, and their applications to the study of NOM. We discuss some basics of how to acquire high-quality and quantitative solid-state (13)C NMR spectra, and address some common technical mistakes that lead to unreliable spectra of NOM. The identification of specific functional groups in NOM, primarily based on (13)C spectral-editing techniques, is described and the theoretical background of some recently-developed spectral-editing techniques is provided. Applications of solid-state NMR to investigating nitrogen (N) in NOM are described, focusing on limitations of the widely used (15)N CP/MAS experiment and the potential of improved advanced NMR techniques for characterizing N forms in NOM. Then techniques used for identifying proximities, heterogeneities and domains are reviewed, and some examples provided. In addition, NMR techniques for studying segmental dynamics in NOM are reviewed. We also briefly discuss applications of solid-state NMR to NOM from various sources, including soil organic matter, aquatic organic matter, organic matter in atmospheric particulate matter, carbonaceous meteoritic organic matter, and fossil fuels. Finally, examples of NMR-based structural models and an outlook are provided. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. 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.

  9. $\\beta$-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.

  10. The acquisition of multidimensional NMR spectra within a single scan

    Science.gov (United States)

    Frydman, Lucio; Scherf, Tali; Lupulescu, Adonis

    2002-01-01

    A scheme enabling the complete sampling of multidimensional NMR domains within a single continuous acquisition is introduced and exemplified. Provided that an analyte's signal is sufficiently strong, the acquisition time of multidimensional NMR experiments can thus be shortened by orders of magnitude. This could enable the characterization of transient events such as proteins folding, 2D NMR experiments on samples being chromatographed, bring the duration of higher dimensional experiments (e.g., 4D NMR) into the lifetime of most proteins under physiological conditions, and facilitate the incorporation of spectroscopic 2D sequences into in vivo imaging investigations. The protocol is compatible with existing multidimensional pulse sequences and can be implemented by using conventional hardware; its performance is exemplified here with a variety of homonuclear 2D NMR acquisitions. PMID:12461169

  11. 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.

  12. Solid state NMR study calcium phosphate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, J.L.; Facchini, L.; Legrand, A.P. (Laboratoire de Physique Quantique, Paris (France). CNRS, URA421, ESPCI); Rey, C. (CNRS, Toulouse (France). ENSC. Laboratoire de Physico-chimie des Solides); Lemaitre, J. (EPF Lausanne (France). Laboratoire de Technologie des Poudres)

    1990-04-01

    High-resolution {sup 31}P and {sup 1}H NMR spectra at 40 and 121 MHz {sup 31}P and 300 MHz {sup 1}H 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, {beta}-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.

  13. 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.

  14. Fresco paintings studied by unilateral NMR

    Science.gov (United States)

    Proietti, N.; Capitani, D.; Lamanna, R.; Presciutti, F.; Rossi, E.; Segre, A. L.

    2005-11-01

    Unilateral NMR has been used to monitor the state of conservation of frescoes in the Vasari's house in Florence. The causes of deterioration of ancient frescoes are varied, which result in the detachment and crumbling of the painted film from the supporting plaster and in the outcropping of salts. Unilateral measurements of Hahn echo performed on such frescoes have allowed a perfect identification of the detachment of the painted film from the plaster. The presence of soluble salts on the pictorial film affects the spin-spin relaxation times, T2. It is then possible using this technique, to characterize the effect of chemical treatments, of cleansing and consolidation procedures using the distribution of T2 spin-spin relaxation times.

  15. NMR studies of polysaccharides from brown seaweeds

    Energy Technology Data Exchange (ETDEWEB)

    Noseda, M.D.; Tisher, C.A.; Gorin, P.A.J.; Duarte, M.E.R. [Parana Univ., Curitiba, PR (Brazil). Dept. de Bioquimica; Cerezo, A.S. [Buenos Aires Univ. Nacional (Argentina). Dept. de Quimica Organica

    1997-12-31

    Alginic acid is the major intercellular polysaccharide serving as matrix in the brown algae and is comprised of an unbranched chain of (1->4)-linked {beta}-D-mannuronic acid (M) and {alpha}-L-guluronic acid (G), arranged in a blockwise fashion. The composition of the monomer residues and the block structure varies depending on the source of the polymer. The selective binding of cations to alginate accounts for its ability to form gels, which is dependent on the number and lenght of the G-blocks. They are widely used industrially for their ability to retain water, and for their gelling, viscosifying and stabilizing properties (Smidsrod and draget, 1996). In this study, alginate composition and block structure in Sargassum stenophyllum has been determined by chemical methods and NMR spectroscopic analysis. (author) 4 refs., 3 figs.

  16. NMR spectroscopy: a tool for conformational analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  17. Two-Dimensional NMR Lineshape Analysis

    Science.gov (United States)

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

    2016-04-01

    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.

  18. Solid state NMR of sulfa-drugs

    CERN Document Server

    Portieri, A

    2001-01-01

    deducted. Exact positions of the hydrogen has proved to be essential as well in order to improve the calculations. Finally a case study for the REDOR pulse sequence has been carried out. Different attempts to understand the effects influencing this particular experiment have been carried out on 20% and 99% doubly enriched glycine, as well as on a particular sample, doubly enriched BRL55834, but the internuclear distances measured with this technique still displayed some uncertainties that made results not thoroughly reliable. This work has been a study of systems, mostly of sulfa-drugs, showing polymorphic behaviour. Using different means as solid state NMR, X-ray analysis, * and theoretical calculations, we have seen how it is possible to understand results obtained from the different techniques, proving how the study of polymorphic systems needs cooperative advice from the different techniques that are able to detect polymorphic differences. Within the sulfa-drugs I have been mostly concentrating on sulfani...

  19. NMR local coil with adjustable spacing

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, G.T.

    1988-03-22

    A local coil assembly for use in NMR imaging is described which comprises: a base; a first local coil module mounted to the base and extending upward therefrom; sockets disposed in the base, each at a different distance from the first local coil module; a second local coil module having a connector therein which mates with each of the sockets to enable the second local coil module to be connected to the base at any one of the sockets; and a set of reactive components. The values of the respective reactive components are selected such that the second local oil module may be connected to any of the sockets without any substantial change in the resonant frequency of the assembly.

  20. Solid-state NMR structures of integral membrane proteins.

    Science.gov (United States)

    Patching, Simon G

    2015-01-01

    Solid-state NMR is unique for its ability to obtain three-dimensional structures and to measure atomic-resolution structural and dynamic information for membrane proteins in native lipid bilayers. An increasing number and complexity of integral membrane protein structures have been determined by solid-state NMR using two main methods. Oriented sample solid-state NMR uses macroscopically aligned lipid bilayers to obtain orientational restraints that define secondary structure and global fold of embedded peptides and proteins and their orientation and topology in lipid bilayers. Magic angle spinning (MAS) solid-state NMR uses unoriented rapidly spinning samples to obtain distance and torsion angle restraints that define tertiary structure and helix packing arrangements. Details of all current protein structures are described, highlighting developments in experimental strategy and other technological advancements. Some structures originate from combining solid- and solution-state NMR information and some have used solid-state NMR to refine X-ray crystal structures. Solid-state NMR has also validated the structures of proteins determined in different membrane mimetics by solution-state NMR and X-ray crystallography and is therefore complementary to other structural biology techniques. By continuing efforts in identifying membrane protein targets and developing expression, isotope labelling and sample preparation strategies, probe technology, NMR experiments, calculation and modelling methods and combination with other techniques, it should be feasible to determine the structures of many more membrane proteins of biological and biomedical importance using solid-state NMR. This will provide three-dimensional structures and atomic-resolution structural information for characterising ligand and drug interactions, dynamics and molecular mechanisms of membrane proteins under physiological lipid bilayer conditions.

  1. Solid state NMR study of bone mineral

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.

    1992-01-01

    In high field (9.4 T) CP MASS (cross polarization magic angle sample spinning) studies, in contrast to the scheme in the literature that infers the presence of minor constituents in spectra, we developed a new scheme to suppress the main part of the spectra to show the minor constituents. In order to perform in vivo solid state NMR studies, a double tuned two port surface coil probe was constructed. This probe is a modified version of the traditional Cross probe, which utilizes two 1/4 wave length 50 ohm transmission line, one with open ended and the other with shorted end, to isolate the high and low frequency circuits. The two resonance frequencies in Cross probe were proton and carbon. Our probe is designed to resonate at the proton and phosphorus frequencies, which are much closer to each other and hence more difficult to be tuned and matched simultaneously. Our approach to solve this problem is that instead of using standard 50 ohm transmission lines, we constructed a low capacity open end coaxial transmission line and low inductance shorted end coaxial transmission line. The Q of the phosphorus channel is high. We developed a short contact time cross polarization technique for non-MASS spectroscopy which reduces the signal of the major component of bone mineral to emphasize the minor component. By applying this technique on intact pork bone samples with our home made surface coil, we observed the wide line component, acid phosphate, for the first time. Hydroxyapatite, brushite and octacalcium are considered in the literature to be the model compounds for bone mineral. Cross polarization dynamics has been studied on hydroxyapatite and brushite, which yielded an NMR value for the distance between proton and phosphorus. One and two dimensional CP MASS spectroscopy of octacalcium phosphate were also studied, which revealed the different cross polarization rates and anisotropic channel shifts of acid phosphate and phosphate ions in octacalcium phosphate.

  2. 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)

  3. PepsNMR for the 1H-NMR metabolomic data pre-processing

    OpenAIRE

    Martin, Manon; Legat, Benoît; Leenders, Justine; Vanwinsberghe, Julien; Rousseau, Réjane; Boulanger, Bruno; Eilers, Paul H. C.; De Tullio, Pascal; Govaerts, Bernadette

    2017-01-01

    In the analysis of complex biological samples, control over experimental design and data acquisition procedures cannot ensure alone well-conditioned 1H-NMR spectra with maximal information recovery for data analysis. A third major element affects the accuracy and robustness of the results: the data pre-processing/pre-treatment for which not enough attention is usually devoted, in particular in the metabolomic studies. The usual approach is to use proprietary software provided by the analytica...

  4. Conformationally selective multidimensional chemical shift ranges in proteins from a PACSY database purged using intrinsic quality criteria

    OpenAIRE

    2015-01-01

    We have determined refined multidimensional chemical shift ranges for intra-residue correlations ([superscript 13]C–[superscript 13]C, [superscript 15]N–[superscript 13]C, etc.) in proteins, which can be used to gain type-assignment and/or secondary-structure information from experimental NMR spectra. The chemical-shift ranges are the result of a statistical analysis of the PACSY database of >3000 proteins with 3D structures (1,200,207 [superscript 13]C chemical shifts and >3 million chemical...

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

    Science.gov (United States)

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

    2011-08-01

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

  6. Combined chemometric analysis of (1)H NMR, (13)C NMR and stable isotope data to differentiate organic and conventional milk.

    Science.gov (United States)

    Erich, Sarah; Schill, Sandra; Annweiler, Eva; Waiblinger, Hans-Ulrich; Kuballa, Thomas; Lachenmeier, Dirk W; Monakhova, Yulia B

    2015-12-01

    The increased sales of organically produced food create a strong need for analytical methods, which could authenticate organic and conventional products. Combined chemometric analysis of (1)H NMR-, (13)C NMR-spectroscopy data, stable-isotope data (IRMS) and α-linolenic acid content (gas chromatography) was used to differentiate organic and conventional milk. In total 85 raw, pasteurized and ultra-heat treated (UHT) milk samples (52 organic and 33 conventional) were collected between August 2013 and May 2014. The carbon isotope ratios of milk protein and milk fat as well as the α-linolenic acid content of these samples were determined. Additionally, the milk fat was analyzed by (1)H and (13)C NMR spectroscopy. The chemometric analysis of combined data (IRMS, GC, NMR) resulted in more precise authentication of German raw and retail milk with a considerably increased classification rate of 95% compared to 81% for NMR and 90% for IRMS using linear discriminate analysis.

  7. An Enzyme Kinetics Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Olsen, Robert J.; Olsen, Julie A.; Giles, Greta A.

    2010-01-01

    An experiment using [superscript 1]H NMR spectroscopy to observe the kinetics of the acylase 1-catalyzed hydrolysis of "N"-acetyl-DL-methionine has been developed for the organic laboratory. The L-enantiomer of the reactant is hydrolyzed completely in less than 2 h, and [superscript 1]H NMR spectroscopic data from a single sample can be worked up…

  8. Dispersion Properties of NMR Relaxation for Crude Oil

    Institute of Scientific and Technical Information of China (English)

    Xie Ranhong; Xiao Lizhi

    2007-01-01

    Special requirements for design of tools used for wireline NMR logging and NMR logging while drilling and for interpretation model are demanded due to the dispersion properties of NMR relaxation for crude oil.NMR longitudinal relaxation time (T1) and transverse relaxation time (T2) of the dead oil samples with different viscosities were measured by NMR spectrometers with a Larmor frequency of 2 MHz and 23 MHz at five different temperatures respectively.The results showed that T1 was obviously dependent on the Larmor frequency of NMR spectrometer.The degree of T1 dispersion became stronger with the increasing crude oil viscosity,Larmor frequency and the viscosity/temperature ratio.T2 was independent of NMR spectrometer measuring frequency.It is suggested that the resonance frequency should be selected lower than 2 MHz when measuring T1 in logging while-drilling and that T1 dispersion should be corrected when Larmor frequency is higher than 2 MHz.

  9. Molecular dynamics simulations on PGLa using NMR orientational constraints.

    Science.gov (United States)

    Sternberg, Ulrich; Witter, Raiker

    2015-11-01

    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. Benchmarking NMR experiments: a relational database of protein pulse sequences.

    Science.gov (United States)

    Senthamarai, Russell R P; Kuprov, Ilya; Pervushin, Konstantin

    2010-03-01

    Systematic benchmarking of multi-dimensional protein NMR experiments is a critical prerequisite for optimal allocation of NMR resources for structural analysis of challenging proteins, e.g. large proteins with limited solubility or proteins prone to aggregation. We propose a set of benchmarking parameters for essential protein NMR experiments organized into a lightweight (single XML file) relational database (RDB), which includes all the necessary auxiliaries (waveforms, decoupling sequences, calibration tables, setup algorithms and an RDB management system). The database is interfaced to the Spinach library (http://spindynamics.org), which enables accurate simulation and benchmarking of NMR experiments on large spin systems. A key feature is the ability to use a single user-specified spin system to simulate the majority of deposited solution state NMR experiments, thus providing the (hitherto unavailable) unified framework for pulse sequence evaluation. This development enables predicting relative sensitivity of deposited implementations of NMR experiments, thus providing a basis for comparison, optimization and, eventually, automation of NMR analysis. The benchmarking is demonstrated with two proteins, of 170 amino acids I domain of alphaXbeta2 Integrin and 440 amino acids NS3 helicase.

  12. 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.

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

    Science.gov (United States)

    Cobas, Carlos; Iglesias, Isaac; Seoane, Felipe

    2015-08-01

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

  14. 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.

  15. Local silico-aluminophosphate interfaces within phosphated H-ZSM-5 zeolites

    NARCIS (Netherlands)

    Van Der Bij, Hendrik E.; Weckhuysen, Bert M.

    2014-01-01

    In order to elucidate phosphorus-zeolite H-ZSM-5 interactions, a variety of phosphorus-modified zeolite H-ZSM-5 materials were studied in a multi-spectroscopic manner. By deploying single pulse 27Al, 31P MAS NMR, 2D heteronuclear 27Al-31P correlation (HETCOR), 27Al MQ MAS NMR spectroscopy, TPD of py

  16. NMR studies on polyphosphide Ce6Ni6P17

    Science.gov (United States)

    Koyama, T.; Yamada, H.; Ueda, K.; Mito, T.; Aoyama, Y.; Nakano, T.; Takeda, N.

    2016-02-01

    We report the result of 31P nuclear magnetic resonance (NMR) studies on Ce6Ni6P17. The observed NMR spectra show a Lorentzian-type and an asymmetric shapes, reflecting the local symmetry around each P site in the cubic unit cell. We have identified the observed NMR lines corresponding to three inequivalent P sites and deduced the temperature dependence of the Knight shift for each site. The Knight shifts increase with decreasing temperature down to 1.5 K, indicating a localized spin system of Ce6Ni6P17. Antiferromagnetic correlation between 4f spins is suggested from the negative sign of the Weiss-temperature.

  17. 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.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    This paper outlines the advantages and disadvantages of using high throughput NMR metabolomics for nutritional studies with emphasis on the workflow and data analytical methods for generation of new knowledge. The paper describes one-by-one the major research activities in the interdisciplinary...... structures for multivariate pattern recognition methods and (3) NMR for providing a unique fingerprint of the lipoprotein status of the subject. For the first time in history, by combining NMR spectroscopy and chemometrics we are able to perform inductive nutritional research as a complement to the deductive...

  19. NMR contributions to structural dynamics studies of intrinsically disordered proteins☆

    Science.gov (United States)

    Konrat, Robert

    2014-01-01

    Intrinsically disordered proteins (IDPs) are characterized by substantial conformational plasticity. Given their inherent structural flexibility X-ray crystallography is not applicable to study these proteins. In contrast, NMR spectroscopy offers unique opportunities for structural and dynamic studies of IDPs. The past two decades have witnessed significant development of NMR spectroscopy that couples advances in spin physics and chemistry with a broad range of applications. This article will summarize key advances in basic physical-chemistry and NMR methodology, outline their limitations and envision future R&D directions. PMID:24656082

  20. On the use of ultracentrifugal devices for sedimented solute NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bertini, Ivano, E-mail: ivanobertini@cerm.unifi.it [University of Florence, Center for Magnetic Resonance (CERM) (Italy); Engelke, Frank [Bruker Biospin GmbH (Germany); Gonnelli, Leonardo [University of Florence, Center for Magnetic Resonance (CERM) (Italy); Knott, Benno [Bruker Biospin GmbH (Germany); Luchinat, Claudio, E-mail: luchinat@cerm.unifi.it [University of Florence, Center for Magnetic Resonance (CERM) (Italy); Osen, David [Bruker Biospin GmbH (Germany); Ravera, Enrico [University of Florence, Center for Magnetic Resonance (CERM) (Italy)

    2012-10-15

    We have recently proposed sedimented solute NMR (SedNMR) as a solid-state method to access biomolecules without the need of crystallization or other sample manipulation. The drawback of SedNMR is that samples are intrinsically diluted and this is detrimental for the signal intensity. Ultracentrifugal devices can be used to increase the amount of sample inside the rotor, overcoming the intrinsic sensitivity limitation of the method. We designed two different devices and we here report the directions for using such devices and the relevant equations for determining the parameters for sedimentation.

  1. Chiral NMR solvating additives for differentiation of enantiomers.

    Science.gov (United States)

    Uccello-Barretta, Gloria; Balzano, Federica

    2013-01-01

    This chapter will describe the general features and main categories of chiral solvating agents (CSAs) for NMR spectroscopy, spanning from low-medium sized CSAs to macrocyclic ones. CSAs based on chiral ionic liquids (CILs) will be introduced in view of their increasing popularity, and, finally, a short paragraph will be dedicated to special applications of CSAs in particular experimental conditions. Several valuable works, which are mainly devoted to investigate enantiodifferentiation mechanisms by NMR, will not be discussed. The main objective is to identify the current trend in the research areas dedicated to the development of new CSAs for NMR spectroscopy.

  2. Characterization of a chiral nematic mesoporous organosilica using NMR

    Science.gov (United States)

    Manning, Alan; Shopsowitz, Kevin; Giese, Michael; MacLachlan, Mark; Dong, Ronald; Michal, Carl

    2012-10-01

    Using templation with nanocrystalline cellulose, a mesoporous organosilica film with a chiral nematic pore structure has recently been developed. [1] We have used a variety of Nuclear Magnetic Resonance (NMR) techniques to characterize the pore structure. The pore size distribution has been found by analyzing the freezing point depression of absorbed water via NMR cryoporometry. The effective longitudinal and transverse pore diameters for diffusing water were investigated with Pulsed-Field Gradient (PFG) NMR and compared to a 1-D connected-pore model. Preliminary data on testing imposed chiral ordering in absorbed liquid crystals is also presented. [4pt] [1] K.E. Shopsowitz et al. JACS 134(2), 867 (2012)

  3. Nanoscale NMR and NQR with Nitrogen Vacancy Centers

    Science.gov (United States)

    Urbach, Elana; Lovchinsky, Igor; Sanchez-Yamagishi, Javier; Choi, Soonwon; Bylinskii, Alexei; Dwyer, Bo; Andersen, Trond; Sushkov, Alex; Park, Hongkun; Lukin, Mikhail

    2016-05-01

    Nuclear quadrupole resonance (NQR) is a powerful tool which is used to detect quadrupolar interaction in nuclear spins with I > 1/2. Conventional NQR and NMR technology, however, rely on measuring magnetic fields from a macroscopic number of spins. Extending NMR and NQR techniques to the nanoscale could allow us to learn structural information about interesting materials and biomolecules. We present recent progress on using Nitrogen-Vacancy (NV) centers in diamond to perform room temperature nanoscale NMR and NQR spectroscopy on small numbers of nuclear spins in hexagonal boron nitride.

  4. 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.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    quality chalks independently of their sedimentological and/or diagenetic history. The study aims to develop an NMR-based approach to characterize a broad range of chalk samples. The provided laboratory low-field NMR chalk classification can be used as a guide to interpret NMR logging data...... size and T2 logarithmic (T2lm) was calculated. It is apparent that tight chalks, whether their characteristics are sedimentological or diagenetic, yield smaller pore body sizes (T2lm well as narrower pore throats (average radius

  6. 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.

  7. Lorentz-to-Gauss multiplication (LGM) in FT NMR

    Energy Technology Data Exchange (ETDEWEB)

    Makhiyanov, N. [Production Association ``Nizhnekamskneftekhym``, Nizhnekamsk, Tatarstan (Russian Federation); Kupka, T. [Uniwersytet Slaski, Katowice (Poland)]|[Zaklad Fizyki Ciala Stalego, Polska Akademia Nauk, Zabrze (Poland); Pasterna, G. [Institute of Nuclear Physics, Cracow (Poland); Dziegielewski, J.O. [Uniwersytet Slaski, Katowice (Poland)

    1994-12-31

    High resolution proton and carbon NMR spectra of macromolecules and biomolecules are often overcrowded and with many partly overlapped signals. Several data processing methods to resolve partly overlapped NMR peaks have been reported. Among the Lorentz-to-Gauss and CDRE (Convulsion Difference Resolution Enhancement) methods are wide used. In this work calculation of the best set of parameters were carried out from a raw spectral data (initial FID and the corresponding untreated spectrum) and a method of prediction of optimal Lorentz-to-Gauss method parameters are suggested. The feasibility of this approach to improve the quality of NMR spectra from various resonating nuclei was shown too. 8 refs, 1 fig.

  8. The PAW/GIPAW approach for computing NMR parameters: a new dimension added to NMR study of solids.

    Science.gov (United States)

    Charpentier, Thibault

    2011-07-01

    In 2001, Mauri and Pickard introduced the gauge including projected augmented wave (GIPAW) method that enabled for the first time the calculation of all-electron NMR parameters in solids, i.e. accounting for periodic boundary conditions. The GIPAW method roots in the plane wave pseudopotential formalism of the density functional theory (DFT), and avoids the use of the cluster approximation. This method has undoubtedly revitalized the interest in quantum chemical calculations in the solid-state NMR community. It has quickly evolved and improved so that the calculation of the key components of NMR interactions, namely the shielding and electric field gradient tensors, has now become a routine for most of the common nuclei studied in NMR. Availability of reliable implementations in several software packages (CASTEP, Quantum Espresso, PARATEC) make its usage more and more increasingly popular, maybe indispensable in near future for all material NMR studies. The majority of nuclei of the periodic table have already been investigated by GIPAW, and because of its high accuracy it is quickly becoming an essential tool for interpreting and understanding experimental NMR spectra, providing reliable assignments of the observed resonances to crystallographic sites or enabling a priori prediction of NMR data. The continuous increase of computing power makes ever larger (and thus more realistic) systems amenable to first-principles analysis. In the near future perspectives, as the incorporation of dynamical effects and/or disorder are still at their early developments, these areas will certainly be the prime target.

  9. Dilute Bicellar Solutions for Structural NMR Work

    Science.gov (United States)

    Struppe, Jochem; Vold, Regitze R.

    1998-12-01

    Deuterium NMR spectroscopy has been employed to characterize the concentration dependence of orientational order in DMPC/DHPC bicellar solutions with molar ratiosq= [DMPC]/[DHPC] = 3.3, 2.7, and 2.3. The stability of a discotic nematic phase can, in general, be predicted from a simple Onsager picture involving the size and concentration of the mesogenic unit, but for the bicellar solutions this model is not adequate. Specifically, macroscopic alignment is observed at total lipid concentrations well below that, 1-10% (w/w) predicted by Onsager's model. Thus the discotic nematic phase is stable to ≈3-5% (w/w) forq= 3.3-2.3, and the bicellar order is highest just before phase separation occurs at the minimum total phospholipid concentration. This implies the presence of a DHPCbic⇄ DHPCsolequilibrium in establishing bicellar size, thereby extending the range of concentrations for which alignment occurs. Bicellar morphology has been verified for a wide range of concentrations, temperatures, andq-values, but as viscosity measurements demonstrate, major morphological changes take place as the temperature is reduced below 30°C.

  10. The Doppler effect in NMR spectroscopy.

    Science.gov (United States)

    Guéron, Maurice

    2003-02-01

    An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

  11. Studies on metabolic regulation using NMR spectroscopy.

    Science.gov (United States)

    Bachelard, H; Badar-Goffer, R; Ben-Yoseph, O; Morris, P; Thatcher, N

    1993-01-01

    The effects of hypoxia and hypoglycaemia on cerebral metabolism and calcium have been studied using multinuclear magnetic resonance spectroscopy. 13C MRS showed that severe hypoxia did not cause any further increase in metabolic flux into lactate seen in mild hypoxia, but there was a further increase in 13C labelling of alanine and glycerol 3-phosphate. These results are discussed in terms of the ability of lactate dehydrogenase to maintain normal levels of NADH in mild hypoxia, but not in severe hypoxia. We conclude that glycerol 3-phosphate and alanine may provide novel means of monitoring severe hypoxia whereas lactate is a reliable indicator only of mild hypoxia. 19F- and 31P NMR spectroscopy showed that neither hypoxia nor hypoglycaemia alone caused any significant change in [Ca2+]i. Combined sequential insults (hypoxia, followed by hypoxia plus hypoglycaemia), or vice versa, produced a 100% increase in [Ca2+]i, whereas immediate exposure to the combined insult (hypoxia plus hypoglycaemia) resulted in a large 5-fold increase in [Ca2+]i, with severe irreversible effects on the energy state. These results are discussed in terms of metabolic adaptation to the single type of insult, which renders the tissue less vulnerable to the combined insult. The effects of this combined insult are far more severe than those caused by glutamate or NMDA, which throws doubt on the current excitoxic hypothesis of cell damage.

  12. NMR methods for beer characterization and quality control.

    Science.gov (United States)

    Rodrigues, J E; Gil, A M

    2011-12-01

    The use of high-resolution NMR spectroscopy in the brewing industry is described; most studies having aimed at assessing the composition of beer and its raw materials and correlating it to a variety of quality parameters. First, the application of NMR to the qualitative characterization of beer is reviewed, addressing both targeted and untargeted methods and focusing on both beer extracts and direct beer analysis. A subsequent chapter addresses the NMR studies, which envisage the development of new rapid methods for beer analysis and quality control, such as site-specific natural fractionation-NMR and multivariate data analysis methods for marker search or rapid compound quantification. Finally, possible future perspectives toward a deeper and more complete understanding of beer and its brewing process are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

  13. 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.

  14. Detection of low-populated reaction intermediates with hyperpolarized NMR.

    Science.gov (United States)

    Jensen, Pernille R; Meier, Sebastian; Ardenkjaer-Larsen, Jan H; Duus, Jens Ø; Karlsson, Magnus; Lerche, Mathilde H

    2009-09-14

    Hyperpolarized (13)C NMR spectroscopy can provide the sensitivity and spectral resolution to detect, identify and quantify low-populated reaction intermediates, thus yielding direct chemical information on reaction mechanisms in real-time assays.

  15. Study of molecular interactions with 13C DNP-NMR.

    Science.gov (United States)

    Lerche, Mathilde H; Meier, Sebastian; Jensen, Pernille R; Baumann, Herbert; Petersen, Bent O; Karlsson, Magnus; Duus, Jens Ø; Ardenkjaer-Larsen, Jan H

    2010-03-01

    NMR spectroscopy is an established, versatile technique for the detection of molecular interactions, even when these interactions are weak. Signal enhancement by several orders of magnitude through dynamic nuclear polarization alleviates several practical limitations of NMR-based interaction studies. This enhanced non-equilibrium polarization contributes sensitivity for the detection of molecular interactions in a single NMR transient. We show that direct (13)C NMR ligand binding studies at natural isotopic abundance of (13)C gets feasible in this way. Resultant screens are easy to interpret and can be performed at (13)C concentrations below muM. In addition to such ligand-detected studies of molecular interaction, ligand binding can be assessed and quantified with enzymatic assays that employ hyperpolarized substrates at varying enzyme inhibitor concentrations. The physical labeling of nuclear spins by hyperpolarization thus provides the opportunity to devise fast novel in vitro experiments with low material requirement and without the need for synthetic modifications of target or ligands.

  16. Metabolic pathway visualization in living yeast by DNP-NMR.

    Science.gov (United States)

    Meier, Sebastian; Karlsson, Magnus; Jensen, Pernille R; Lerche, Mathilde H; Duus, Jens Ø

    2011-10-01

    Central carbon metabolism of living Saccharomyces cerevisiae is visualized by DNP-NMR. Experiments are conducted as real time assays that detect metabolic bottlenecks, pathway use, reversibility of reactions and reaction mechanisms in vivo with subsecond time resolution.

  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. Observations of Quantum Dynamics by Solution-State NMR Spectroscopy

    CERN Document Server

    Pravia, M A; Weinstein, Yu S; Price, M D; Teklemariam, G; Nelson, R J; Sharf, Y; Somaroo, S S; Tseng, C H; Havel, T F; Cory, D G

    1999-01-01

    NMR is emerging as a valuable testbed for the investigation of foundational questions in quantum mechanics. The present paper outlines the preparation of a class of mixed states, called pseudo-pure states, that emulate pure quantum states in the highly mixed environment typically used to describe solution-state NMR samples. It also describes the NMR observation of spinor behavior in spin 1/2 nuclei, the simulation of wave function collapse using a magnetic field gradient, the creation of entangled (or Bell) pseudo-pure states, and a brief discussion of quantum computing logic gates, including the Quantum Fourier Transform. These experiments show that liquid-state NMR can be used to demonstrate quantum dynamics at a level suitable for laboratory exercises.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-15

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

  20. 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.)

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

    African Journals Online (AJOL)

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    3 Department of Physics, Arts and Science Faculty, Dumlupınar University, Kütahya, Turkey. 4 Department ... been studied experimentally and theoretically using nuclear magnetic resonance (NMR) spectroscopy. 1H, 13C, ... INTRODUCTION.

  2. 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.

  3. Interfaces in polymer nanocomposites – An NMR study

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-09

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

  4. 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.

  5. Dihydroflavanonols from Cedrus deodara, A (13)C NMR study.

    Science.gov (United States)

    Agrawal, P K; Agarwal, S K; Rastogi, R P; Osterdahal, B G

    1981-09-01

    High resolution (13)C NMR study of taxifolin, cedeodarin, cedrin and their methyl ethers allowed unambiguous placement of the Me in 5,7-dihydroxyflavanonol nucleus, besides providing other valuable information on the substitution pattern in the molecule.

  6. A Quick and Easy Simplification of Benzocaine's NMR Spectrum

    Science.gov (United States)

    Carpenter, Suzanne R.; Wallace, Richard H.

    2006-04-01

    The preparation of benzocaine is a common experiment used in sophomore-level organic chemistry. Its straightforward procedure and predictable good yields make it ideal for the beginning organic student. Analysis of the product via NMR spectroscopy, however, can be confusing to the novice interpreter. An inexpensive, quick, and effective method for simplifying the NMR spectrum is reported. The method results in a spectrum that is cleanly integrated and more easily interpreted.

  7. Analyzing protein-ligand interactions by dynamic NMR spectroscopy.

    Science.gov (United States)

    Mittermaier, Anthony; Meneses, Erick

    2013-01-01

    Nuclear magnetic resonance (NMR) spectroscopy can provide detailed information on protein-ligand interactions that is inaccessible using other biophysical techniques. This chapter focuses on NMR-based approaches for extracting affinity and rate constants for weakly binding transient protein complexes with lifetimes of less than about a second. Several pulse sequences and analytical techniques are discussed, including line-shape simulations, spin-echo relaxation dispersion methods (CPMG), and magnetization exchange (EXSY) experiments.

  8. Editorial: New 1.2 GHz NMR Spectrometers- New Horizons?

    Science.gov (United States)

    Schwalbe, Harald

    2017-08-21

    The latest ultrahigh-field NMR spectrometers are a huge technological challenge that require large financial investments. In his Guest Editorial, Harald Schwalbe justifies the need for spectrometers with higher magnetic field strengths. The important results from previous generations of high-field NMR spectrometers are discussed, and research areas are identified that will benefit from the latest spectrometers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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.

  10. Perspectives on a Solid State NMR Quantum Computer

    OpenAIRE

    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.

  11. 2D NMR-spectroscopic screening reveals polyketides in ladybugs

    OpenAIRE

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

    2011-01-01

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

  12. 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.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    The demand for high precision calculations of NMR shieldings (or their related values, chemical shifts δ) and spin-spin coupling constants facilitating and supporting detailed interpretations of NMR spectra increases hand in hand with the development of computational techniques and hardware...... for molecular equilibrium geometries creates a demand for zero point vibrational and temperature corrections. In this chapter we describe briefly the theory behind rovibrational corrections and review then some important contributions to this field....

  14. Equilibrium and structure of the Al(III)-ethylenediamine-N,N'-bis(3-hydroxy-2-propionate) (EDBHP) complex. A multi-method study by potentiometry, NMR, ESI MS and X-ray diffraction.

    Science.gov (United States)

    Jószai, Róbert; Kerekes, Imola; Satoshi, Igarashi; Sawada, Kiyoshi; Zékány, László; Tóth, Imre

    2006-07-14

    The equilibrium and structure of the complex formed by Al(III) and ethylenediamine-N,N'-bis(3-hydroxy-2-propionate) (EDBHP2-) have been studied using pH-potentiometry, 1H and 27Al NMR, ESI MS and single crystal X-ray diffraction methods. The EDBHP ligand is a strong Al-binder in aqueous solution for pH between 4 and 8 and for c(Al) = c(EDBHP)> or = 0.1 mmol dm(-3). The dominating complex identified by ESI MS and potentiometry is a neutral dimer, Al2L2(OH)2, with logbeta(22-2) = 14.16 +/- 0.03. In the solid Al2(EDBHP)2(OH)2.2H2O the Al(III) ions are connected through a double hydroxo bridge. Both four-dentate organic ligands are coordinated terminally through two carboxylate groups and two N-donors forming three five-membered chelate rings. The hydroxyl groups of the ligand EDBHP remain protonated and are not coordinated to the aluminium ions. The structure and composition of the dimer are very likely the same in solution and the solid state.

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

    Directory of Open Access Journals (Sweden)

    Zhou Gong

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

  16. The development of solid-state NMR of membrane proteins.

    Science.gov (United States)

    Opella, Stanley J

    Most biological functions are carried out in supramolecular assemblies. As a result of their slow reorientation in solution, these assemblies have been resistant to the widely employed solution NMR approaches. The development of solid-state NMR to first of all overcome the correlation time problem and then obtain informative high-resolution spectra of proteins in supramolecular assemblies, such as virus particles and membranes, is described here. High resolution solid-state NMR is deeply intertwined with the history of NMR, and the seminal paper was published in 1948. Although the general principles were understood by the end of the 1950s, it has taken more than fifty years for instrumentation and experimental methods to become equal to the technical problems presented by the biological assemblies of greatest interest. It is now possible to obtain atomic resolution structures of viral coat proteins in virus particles and membrane proteins in phospholipid bilayers by oriented sample solid-state NMR methods. The development of this aspect of the field of solid-state NMR is summarized in this review article.

  17. Protein folding on the ribosome studied using NMR spectroscopy

    Science.gov (United States)

    Waudby, Christopher A.; Launay, Hélène; Cabrita, Lisa D.; Christodoulou, John

    2013-01-01

    NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome–nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity. PMID:24083462

  18. Amide-Exchange-Rate-Edited NMR (AERE-NMR) Experiment:A Novel Method for Resolving Overlapping Resonances

    Institute of Scientific and Technical Information of China (English)

    LIU Xue-Hui; LIN Dong-Hai

    2007-01-01

    This paper describes an amide-exchange-rate-edited (AERE) NMR method that can effectively alleviate the problem of resonance overlap for proteins and peptides. This method exploits the diversity of amide proton exchange rates and consists of two complementary experiments: (1) SEA (solvent exposed amide)-type NMR experiments to map exchangeable surface residues whose amides are not involved in hydrogen bonding, and (2) presat-type NMR experiments to map solvent inaccessibly buried residues or nonexchangeable residues located in hydrogen-bonded secondary structures with properly controlled saturation transfer via amide proton exchanges with the solvent. This method separates overlapping resonances in a spectrum into two complementary spectra. The AERE-NMR method was demonstrated with a sample of 15N/13C/2H(70%) labeled ribosome-inactivating protein trichosanthin of 247 residues.

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

    Science.gov (United States)

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

    2015-04-01

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

  20. 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.