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Sample records for state nmr study

  1. Solid state NMR study of cumbaru flour

    International Nuclear Information System (INIS)

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

    2001-01-01

    The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13 C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T 1 H ρ). Knowing that the chemical structure and molecular dynamic are extremely necessary route to obtain information on the polysaccharides, this work contributes to the classification of the seed containing in the cumbaru fruit to get response on its application. To obtain the initial responses for our purposes some solid state NMR techniques were chosen. The CPMAS 13 C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13 C NMR spectrum showed the presence of domains with distinct molecular mobility, because these domains will differ basically in the distribution size and chain packing. The variable contact time experiment was used to analyse the distribution form of 13 C decays, which give us more information about sample heterogeneity. The T 1 H ρHr values were obtained from the variable contact time and by delayed contact time experiment, because these parameter indicate the order of polysaccharides. From the values of this parameter, we found that this polysaccharide is completely non-ordered. (author)

  2. Solid-state NMR studies of nucleic acid components

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Hodgkinson, P.

    2015-01-01

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

  3. Two dimensional solid state NMR

    International Nuclear Information System (INIS)

    Kentgens, A.P.M.

    1987-01-01

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

  4. Solid-state NMR studies of form I of atorvastatin calcium.

    Science.gov (United States)

    Wang, Wei David; Gao, Xudong; Strohmeier, Mark; Wang, Wei; Bai, Shi; Dybowski, Cecil

    2012-03-22

    Solid-state (13)C, (19)F, and (15)N magic angle spinning NMR studies of Form I of atorvastatin calcium are reported, including chemical shift tensors of all resolvable carbon sites and fluorine sites. The complete (13)C and (19)F chemical shift assignments are given based on an extensive analysis of (13)C-(1)H HETCOR and (13)C-(19)F HETCOR results. The solid-state NMR data indicate that the asymmetric unit of this material contains two atorvastatin molecules. A possible structure of Form I of atorvastatin calcium (ATC-I), derived from solid-state NMR data and density functional theory calculations of various structures, is proposed for this important active pharmaceutical ingredient (API).

  5. Blends of natural rubber and polyurethane lattices studied by solid-state NMR

    International Nuclear Information System (INIS)

    Ricardo, Nagila M.P.S.; Franca, Francisco C.F. de; Price, Colin; Heatley, Frank

    2001-01-01

    Molecular mixing in films formed from a mixture of a polyurethane and natural rubber lattices has been studied using 1 H and 13 C solid-state NMR. The techniques employed include 1 H relaxation measurements, and 13 C cross-polarisation and direct excitation methods. The spectra of the blends were essentially a weighted superposition of the spectra of the individual components, indicating that the polyurethane and rubber remained phase-separated in large domains. (author)

  6. The structure of poly(carbonsuboxide) on the atomic scale: a solid-state NMR study.

    Science.gov (United States)

    Schmedt auf der Günne, Jörn; Beck, Johannes; Hoffbauer, Wilfried; Krieger-Beck, Petra

    2005-07-18

    In this contribution we present a study of the structure of amorphous poly(carbonsuboxide) (C3O2)x by 13C solid-state NMR spectroscopy supported by infrared spectroscopy and chemical analysis. Poly(carbonsuboxide) was obtained by polymerization of carbonsuboxide C3O2, which in turn was synthesized from malonic acid bis(trimethylsilylester). Two different 13C labeling schemes were applied to probe inter- and intramonomeric bonds in the polymer by dipolar solid-state NMR methods and also to allow quantitative 13C MAS NMR spectra. Four types of carbon environments can be distinguished in the NMR spectra. Double-quantum and triple-quantum 2D correlation experiments were used to assign the observed peaks using the through-space and through-bond dipolar coupling. In order to obtain distance constraints for the intermonomeric bonds, double-quantum constant-time experiments were performed. In these experiments an additional filter step was applied to suppress contributions from not directly bonded 13C,13C spin pairs. The 13C NMR intensities, chemical shifts, connectivities and distances gave constraints for both the polymerization mechanism and the short-range order of the polymer. The experimental results were complemented by bond lengths predicted by density functional theory methods for several previously suggested models. Based on the presented evidence we can unambiguously exclude models based on gamma-pyronic units and support models based on alpha-pyronic units. The possibility of planar ladder- and bracelet-like alpha-pyronic structures is discussed.

  7. Natural abundant solid state NMR studies in designed tripeptides for differentiation of multiple conformers.

    Science.gov (United States)

    Jayanthi, S; Chatterjee, Bhaswati; Raghothama, S

    2009-10-01

    Solid state NMR (SSNMR) experiments on heteronuclei in natural abundance are described for three synthetically designed tripeptides Piv-(L)Pro-(L)Pro-(L)Phe-OMe (1), Piv-(D)Pro-(L)Pro-(L)Phe-OMe (2), and Piv-(D)Pro-(L)Pro-(L)Phe-NHMe (3). These peptides exist in different conformation as shown by solution state NMR and single crystal X-ray analysis (Chatterjee et al., Chem Eur J 2008, 14, 6192). In this study, SSNMR has been used to probe the conformations of these peptides in their powder form. The (13)C spectrum of peptide (1) showed doubling of resonances corresponding to cis/cis form, unlike in solution where the similar doubling is attributed to cis/trans form. This has been confirmed by the chemical shift differences of C(beta) and C(gamma) carbon of Proline in peptide (1) both in solution and SSNMR. Peptide (2) and (3) provided single set of resonances which represented all trans form across the di-Proline segment. The results are in agreement with the X-ray analysis. Solid state (15)N resonances, especially from Proline residues provided additional information, which is normally not observable in solution state NMR. (1)H chemical shifts are also obtained from a two-dimensional heteronuclear correlation experiment between (1)H--(13)C. The results confirm the utility of NMR as a useful tool for identifying different conformers in peptides in the solid state. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 851-860, 2009.

  8. Studying the molecular determinants of potassium channel structure and function in membranes by solid-state NMR

    NARCIS (Netherlands)

    van der Cruijsen, Elwin

    2014-01-01

    Solid-state Nuclear Magnetic Resonance (ssNMR) has made remarkable progress in the structural characterization of membrane proteins systems at atomic resolution. Such studies can be further aided by the use of molecular dynamic simulations. Moreover, ssNMR data can be directly compared to functional

  9. Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes

    Directory of Open Access Journals (Sweden)

    Jean-Christophe Daigle

    2018-01-01

    Full Text Available We report the analysis of comb-like polymers by solid-state NMR. The polymers were previously evaluated as solid-polymer-electrolytes (SPE for lithium-polymer-metal batteries that have suitable ionic conductivity at 60 °C. We propose to develop a correlation between 13C solid-state NMR measurements and phase segregation. 13C solid-state NMR is a perfect tool for differentiating polymer phases with fast or slow motions. 7Li was used to monitor the motion of lithium ions in the polymer, and activation energies were calculated.

  10. Solid state multinuclear NMR. A versatile tool for studying the reactivity of solid systems

    Energy Technology Data Exchange (ETDEWEB)

    MacKenzie, Kenneth J.D. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P.O. Box 600, Wellington (New Zealand)

    2004-08-31

    Traditionally, X-ray powder diffraction has been a favoured method for studying chemical reactions in the solid state, but the increasing importance of energy-efficient synthesis methods for solids (e.g. sol-gel synthesis, mechanochemical synthesis) has led to the need for an analytical method not dependent on long-range structural periodicity. Multinuclear solid state nuclear magnetic resonance (NMR) represents a technique which is equally applicable to amorphous or crystalline solids, and is now used in increasing numbers of solid state studies.This paper briefly outlines the principles and practical details of this powerful technique and gives examples of its use in solid-state chemistry, particularly in very recent studies of mechanochemical synthesis of advanced sialon ceramics. The temperature at which these technically important silicon aluminium oxynitride compounds are formed can be significantly lowered by high-energy grinding of their components to produce X-ray amorphous precursors. Solid-state NMR has been used to provide detailed information which could not have been obtained by any other means about the chemical environment of the Si and Al atoms in these amorphous precursors, and the various atomic movements undergone as they crystallise to the final product.

  11. Solid-state NMR of inorganic semiconductors.

    Science.gov (United States)

    Yesinowski, James P

    2012-01-01

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

  12. Solid state NMR and LVSEM studies on the hardening of latex modified tile mortar systems

    International Nuclear Information System (INIS)

    Rottstegge, J.; Arnold, M.; Herschke, L.; Glasser, G.; Wilhelm, M.; Spiess, H.W.; Hergeth, W.D.

    2005-01-01

    Construction mortars contain a broad variety of both inorganic and organic additives beside the cement powder. Here we present a study of tile mortar systems based on portland cement, quartz, methyl cellulose and different latex additives. As known, the methyl cellulose stabilizes the freshly prepared cement paste, the latex additive enhances final hydrophobicity, flexibility and adhesion. Measurements were performed by solid state nuclear magnetic resonance (NMR) and low voltage scanning electron microscopy (LVSEM) to probe the influence of the latex additives on the hydration, hardening and the final tile mortar properties. While solid state NMR enables monitoring of the bulk composition, scanning electron microscopy affords visualization of particles and textures with respect to their shape and the distribution of the different phases. Within the alkaline cement paste, the poly(vinyl acetate) (VAc)-based latex dispersions stabilized by poly(vinyl alcohol) (PVA) were found to be relatively stable against hydrolysis. The influence of the combined organic additives methyl cellulose, poly(vinyl alcohol) and latexes stabilized by poly(vinyl alcohol) on the final silicate structure of the cement hydration products is small. But even small amounts of additives result in an increased ratio of ettringite to monosulfate within the final hydrated tile mortar as monitored by 27 Al NMR. The latex was found to be adsorbed to the inorganic surfaces, acting as glue to the inorganic components. For similar latex water interfaces built up by poly(vinyl alcohol), a variation in the latex polymer composition results in modified organic textures. In addition to the networks of the inorganic cement and of the latex, there is a weak network build up by thin polymer fibers, most probably originating from poly(vinyl alcohol). Besides the weak network, polymer fibers form well-ordered textures covering inorganic crystals such as portlandite

  13. Combined solid state and solution NMR studies of α,ε-15N labeled bovine rhodopsin

    International Nuclear Information System (INIS)

    Werner, Karla; Lehner, Ines; Dhiman, Harpreet Kaur; Richter, Christian; Glaubitz, Clemens; Schwalbe, Harald; Klein-Seetharaman, Judith; Khorana, H. Gobind

    2007-01-01

    Rhodopsin is the visual pigment of the vertebrate rod photoreceptor cell and is the only member of the G protein coupled receptor family for which a crystal structure is available. Towards the study of dynamics in rhodopsin, we report NMR-spectroscopic investigations of α,ε- 15 N-tryptophan labeled rhodopsin in detergent micelles and reconstituted in phospholipids. Using a combination of solid state 13 C, 15 N-REDOR and HETCOR experiments of all possible 13 C' i-1 carbonyl/ 15 N i -tryptophan isotope labeled amide pairs, and H/D exchange 1 H, 15 N-HSQC experiments conducted in solution, we assigned chemical shifts to all five rhodopsin tryptophan backbone 15 N nuclei and partially to their bound protons. 1 H, 15 N chemical shift assignment was achieved for indole side chains of Trp35 1.30 and Trp175 4.65 . 15 N chemical shifts were found to be similar when comparing those obtained in the native like reconstituted lipid environment and those obtained in detergent micelles for all tryptophans except Trp175 4.65 at the membrane interface. The results suggest that the integrated solution and solid state NMR approach presented provides highly complementary information in the study of structure and dynamics of large membrane proteins like rhodopsin

  14. 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.      ...

  15. Location of radiation-induced grafted chains in polymers studied by solid-state NMR

    International Nuclear Information System (INIS)

    Whittacker, A.; Liu, H.

    1998-01-01

    In this study styrene and N-phenyl maleimide monomers were grafted onto poly(ethylene) (PE) chains using gamma radiation. Of main interest is the distribution of grafted chains within the polymer matrix, as this will determine the efficacy of mixing with the glassy polymers. It is expected that grafting will occur within the amorphous regions, and especially near the interface of the crystalline and amorphous regions. A suitable method for characterising the location of the grafted chains is solid-state 13 C NMR spectroscopy. The 13 C CPMAS spectrum of the blend of PE and N-phenyl maleimide mixed in the melt at 150 deg C , prior to reaction, is shown above. The spectrum shows the typical peaks for poly(ethylene) due to the amorphous and crystalline phase at 30.5 and 32.5 ppm, respectively. Peaks are also seen in the aromatic and carbonyl region due to the maleimide (not plotted). Experiments will be described where the NMR magnetisation is prepared in either the crystalline and amorphous regions of the poly(ethylene) prior to spin diffusion to the maleimide and styrene fractions. The location of the grafted monomers can then be determined by monitoring the changes in signal of polymer and graft with time

  16. Solid state NMR method development and studies of biological and biomimetic nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yanyan [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    This thesis describes application and development of advanced solid-state nuclear magnetic resonance techniques for complex materials, in particular organic-inorganic nanocomposites and thermoelectric tellurides. The apatite-collagen interface, essential for understanding the biomineralization process in bone and engineering the interface for controlled bio-mimetic synthesis and optimized mechanical properties, is buried within the nanocomposite of bone. We used multinuclear solid-state NMR to study the composition and structure of the interface. Citrate has been identified as the main organic molecule strongly bound to the apatite surface with a density of 1/(2 nm)2, covering 1/6 of the total surface area in bovine bone. Citrate provides more carboxylate groups, one of the key functional groups found to affect apatite nucleation and growth, than all the non-collagenous proteins all together in bone; thus we propose that citrate stabilizes apatite crystals at a very small thickness of ~3 nm (4 unit cells) to increase bone fracture tolerance. The hypothesis has been confirmed in vitro by adding citrate in the bio-mimetic synthesis of polymerhydroxyapatite nanocomposites. The results have shown that the size of hydroxyapatite nanocrystals decreases as increasing citrate concentration. With citrate concentrations comparable to that in body fluids, similar-sized nanocrystals as in bone have been produced. Besides the dimensions of the apatite crystals, the composition of bone also affects its biofunctional and macroscopic mechanical properties; therefore, our team also extended its effort to enhance the inorganic portion in our bio-mimetic synthesis from originally 15 wt% to current 50 wt% compared to 65 wt% in bovine bone, by using Lysine-Leucine hydroxyapatite nucleating diblock co-polypeptide, which forms a gel at very low concentration. In this thesis, various advanced solid state NMR techniques have been employed to characterize nanocomposites

  17. Functional studies using NMR

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  18. Solid state 13 C NMR quantitative study of wood tar pitches

    International Nuclear Information System (INIS)

    Prauchner, Marcos Juliano; Pasa, Vanya Marcia Duarte; Menezes, Sonia Maria Cabral de

    1999-01-01

    In this work, solid-state 13 C NMR is used with other techniques to characterize Eucalyptus tar pitches and to follow their polymerization reactions. The pitches are the residues of distillation (about 50% m;m) of the tar generated in Eucalyptus slow pyrolysis for charcoal production in metal industry

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

    KAUST Repository

    Chu, Shidong; Maltsev, Sergey B.; Emwas, Abdul-Hamid M.; Lorigan, Gary A.

    2010-01-01

    A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2

  20. Functional studies using NMR

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  1. High resolution NMR study of cellulose in solid state and in solution

    International Nuclear Information System (INIS)

    Saint-Germain, Jean

    1983-01-01

    This research thesis reports the study of native cellulose (cotton) and wood by nuclear magnetic resonance (NMR). As far as the cotton spectrum is concerned, the author assigned resonances which more specifically corresponded to amorphous or crystalline areas. Wood was studied in its bulk condition, and resonances have been determined for the different wood components. The behaviour of cellulose in solution in a solvent has been studied by liquid high resolution NMR. The solvation mechanism has been determined and a study of model components of the macromolecule allowed a conformational study of cellulose in this solvent to be performed. Bi-dimensional NMR and longitudinal relaxation time measurements highlighted the existence of an intramolecular hydrogen bond in the cellulose in solution [fr

  2. NMR study on the low-temperature state of LaMn4Al8

    International Nuclear Information System (INIS)

    Muro, Y.; Nakamura, H.; Kohara, T.

    2007-01-01

    The ground state of the quasi-one-dimensional itinerant electron magnet LaMn 4 Al 8 with strong electron correlation has been investigated by NMR. The presence of weak and broad zero-field 55 Mn resonance, corresponding to internal field of 8-11T, indicates slowing down of spins partially released from the spin-singlet-like state in the spin chains

  3. Hydrothermal reaction of albite and a sodium aluminosilicate glass: A solid-state NMR study

    Science.gov (United States)

    Yang, Wang-hong Alex; Kirkpatrick, R. James

    1989-04-01

    We present here a solid-state NMR study of the structure and chemical composition of the products and mechanisms of the reaction of crystalline low albite and a glass of nearly albite composition with aqueous solutions of pH from 1 to 11 at 250°C. For the crystalline albite, there are no detectable bulk or surface structural changes due to aqueous attack, consistent with the idea that both cation exchange and disruption of the aluminosilicate framework occur only near the mineral/solution interface and that the hydrated surface layer, if it exists, is not more than about 30 Å thick. This reaction occurs by solution/reprecipitation, and its rate decreases with increasing solution pH, supporting the idea that the dissolution of feldspar is initiated by cation-exchange. For the glass, the reaction proceeds by cation exchange of protons for Na +, incorporation of molecular water into the bulk glass, and a small amount of depolymerization of the aluminosilicate framework in the interior of the glass. Cation exchange becomes less important with increasing solution pH. The incorporation of molecular water and cation-exchange cause structural changes in the glass via solidstate adjustment without dissolution/reprecipitation. The large cations in the hydrated glass (Na and K) probably have a shell of water molecules around them, with a maximum average coordination number of six. The secondary phases formed from both albite and the glass are often amorphous and can be well characterized by NMR. The compositional and structural variations of the amorphous phases are important factors in these reactions and cannot be ignored in theoretical models of aluminosilicate dissolution. As expected, the aluminum coordination in the secondary phases changes from six-fold to four-fold as the solution pH increases.

  4. Solid state NMR of materials

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Sharon A; Ferguson, David B; Haw, James F [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry

    1994-12-31

    In situ NMR experiments are studied, including probe of several structures such as the structures of the organic adsorbates, Broensted acid sites, other nuclei associated with active sites, and other framework sites. The authors report that in the absence of high concentrations of paramagnetic sites or metal particles, high resolution MAS spectra are relatively easy to obtain and interpret. It is also concluded that NMR can measure spatial distributions and rates of diffusion; and are able to characterize equilibrium structures and the frequencies and amplitudes of molecular motion

  5. (13)C and (15)N solid-state NMR studies on albendazole and cyclodextrin albendazole complexes.

    Science.gov (United States)

    Ferreira, M João G; García, A; Leonardi, D; Salomon, Claudio J; Lamas, M Celina; Nunes, Teresa G

    2015-06-05

    (13)C and (15)N solid-state nuclear magnetic resonance (NMR) spectra were recorded from albendazole (ABZ) and from ABZ:β-cyclodextrin, ABZ:methyl-β-cyclodextrin, ABZ:hydroxypropyl-β-cyclodextrin and ABZ:citrate-β-cyclodextrin, which were prepared by the spray-drying technique. ABZ signals were typical of a crystalline solid for the pure drug and of an amorphous compound obtained from ABZ:cyclodextrin samples. Relevant spectral differences were correlated with chemical interaction between ABZ and cyclodextrins. The number and type of complexes revealed a strong dependence on the cyclodextrin group substituent. Solid-state NMR data were consistent with the presence of stable inclusion complexes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Slow molecular dynamics in the β relaxation of semicrystalline polymers studied by pure exchange 13C solid state NMR

    International Nuclear Information System (INIS)

    Azevedo, Eduardo R. de; Becker-Guedes, Fabio; Bonagamba, Tito J.; Schmidt-Rohr, Klaus; Iowa State University, Ames, IA

    2001-01-01

    The dynamics in the amorphous regions of semicrystalline polymers exert important influences on mechanical properties, but have been notoriously difficult to characterize. Two new solid-state NMR techniques, PUREX (pure exchange) and CODEX (center band-only detection of exchange) NMR, make it possible to analyze the molecular motions near the glass transition in the amorphous regions of semicrystalline polymers. This is achieved by selectively suppressing the otherwise dominant signals of the static segments in the crystallites. We have applied both NMR techniques to study the slow motions near the glass transition in semicrystalline polymers (β relaxation) and in fully amorphous samples for reference. The studied polymers were isotactic poly(1-butene) (iPB1) (form I), syndiotactic and atactic polypropylenes (sPP, and aPP, respectively), as well as polyisobutylene (PIB). We have analyzed the geometry and time scale of the slow molecular motion for all samples and determined the apparent activation energies. (author)

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

    KAUST Repository

    Chu, Shidong

    2010-11-01

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

  8. Solid state NMR studies for a new carbonization process with high temperature preheating

    Science.gov (United States)

    Saito, Koji; Hatakeyama, Moriaki; Komaki, Ikuo; Katoh, Kenji

    2002-01-01

    A new carbonization process with rapid preheating and coke discharging at medium temperature has been developed in Japan. The result of this process shows that even when no or slightly coking coal is by 50 wt% the coking property is improved and a coking coke with cold strength usable at blast furnace can be manufactured with the new carbonization process. The mechanism of the coking property improvement was examined by coal properties using mainly solid state NMR ( 1H CRAMPS and 13C SPE/MAS, CP/MAS) and NMR imaging (single point imaging, in-situ imaging). It has been clarified that the molecular structure of coal is relaxed by the rapid heating treatment and, in addition, there is a close relation between hydrogen bonding and relaxation of the molecular structure of coal.

  9. NMR studies of incommensurate quantum antiferromagnetic state of LiCuVO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. [NHMFL, Florida State University, 1800 E P.Dirac Dr., Tallahassee FL 32310 (United States); Reyes, A.P. [NHMFL, Florida State University, 1800 E P.Dirac Dr., Tallahassee FL 32310 (United States); Ashey, R. [NHMFL, Florida State University, 1800 E P.Dirac Dr., Tallahassee FL 32310 (United States); Caldwell, T. [NHMFL, Los Alamos, NM 87545 (United States); Prokofiev, A. [Goethe University, 60054 Frankfurt (Germany); Assmus, W. [Goethe University, 60054 Frankfurt (Germany); Teitel' baum, G. [E.K.Zavoiskii Institute for Technical Physics of the RAS, Sibirskii Trakt 10/7, Kazan 420029 (Russian Federation)]. E-mail: grteit@kfti.knc.ru

    2006-05-01

    Our {sup 51}V NMR measurements in the LiCuVO{sub 4} single crystal reveal that the classical quadrupole split signal transforms upon lowering temperature to the single line with the shape typical for the systems undergoing the phase transition to the incommensurate magnetic state. The angular dependence of such a lineshape together with the anomalies of the {sup 51}V nuclear spin relaxation rates make it possible to conclude that the low-temperature magnetic order corresponds to the antiferromagnetic state with the incommensurate modulation along the b-axis of the crystal.

  10. NMR studies of incommensurate quantum antiferromagnetic state of LiCuVO 4

    Science.gov (United States)

    Smith, R.; Reyes, A. P.; Ashey, R.; Caldwell, T.; Prokofiev, A.; Assmus, W.; Teitel'baum, G.

    2006-05-01

    Our 51V NMR measurements in the LiCuVO 4 single crystal reveal that the classical quadrupole split signal transforms upon lowering temperature to the single line with the shape typical for the systems undergoing the phase transition to the incommensurate magnetic state. The angular dependence of such a lineshape together with the anomalies of the 51V nuclear spin relaxation rates make it possible to conclude that the low-temperature magnetic order corresponds to the antiferromagnetic state with the incommensurate modulation along the b-axis of the crystal.

  11. Structural study of the membrane protein MscL using cell-free expression and solid-state NMR

    Science.gov (United States)

    Abdine, Alaa; Verhoeven, Michiel A.; Park, Kyu-Ho; Ghazi, Alexandre; Guittet, Eric; Berrier, Catherine; Van Heijenoort, Carine; Warschawski, Dror E.

    2010-05-01

    High-resolution structures of membrane proteins have so far been obtained mostly by X-ray crystallography, on samples where the protein is surrounded by detergent. Recent developments of solid-state NMR have opened the way to a new approach for the study of integral membrane proteins inside a membrane. At the same time, the extension of cell-free expression to the production of membrane proteins allows for the production of proteins tailor made for NMR. We present here an in situ solid-state NMR study of a membrane protein selectively labeled through the use of cell-free expression. The sample consists of MscL (mechano-sensitive channel of large conductance), a 75 kDa pentameric α-helical ion channel from Escherichia coli, reconstituted in a hydrated lipid bilayer. Compared to a uniformly labeled protein sample, the spectral crowding is greatly reduced in the cell-free expressed protein sample. This approach may be a decisive step required for spectral assignment and structure determination of membrane proteins by solid-state NMR.

  12. Investigation of new NMR methods for structural and dynamic studies in the liquid state

    International Nuclear Information System (INIS)

    Desvaux, H.

    1993-01-01

    After a short presentation of the NMR fundements, three new methods of spin -lattice relaxation in liquids are reported. (1) The method consists of measuring the steady-state nuclear magnetization under strong off-resonance rf irradiation as a function of the angle θ between external field and effective field. For purely dipolar relaxation between homonuclear spins under isotropic Brownian molecular rotation, this variation yields the value of the local correlation time. A departure from the theoretical shape reveals the existence of complex motions or complex relaxation mechanisms. These results have been verified by experimental illustrations. Some numerical simulations have been performed for studying the effects of the distribution of chemical shift and for studying the coherence of the local correlation time concept. (2) The improvements of a modified ROESY experiment are discussed. The use of a time-modulated strong off-resonances rf irradiation permits to suppress totally the problems of the NOESY (suppression of cross-relaxation peaks for molecules where ωτ c ≅ 1.1) and of the ROESY (HOHAHA transfer and angular dispersion due to the chemical shift distribution). The angle θ defined previously can be used as a constraint: either to obtain a ratio of the cross over direct dipolar relaxation rates independent on the correlation time value, or to observe the sole chemical exchange. (3) The difference of the relaxation rates of the coherences at zero and two quanta is always exactly the cross relaxation rates measured by the NOESY experiment. The experimental illustration is presented

  13. Parallel β-Sheet Structure of Alanine Tetrapeptide in the Solid State As Studied by Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Asakura, Tetsuo; Horiguchi, Kumiko; Aoki, Akihiro; Tasei, Yugo; Naito, Akira

    2016-09-01

    The structural analysis of alanine oligopeptides is important for understanding the crystalline region in silks from spiders and wild silkworms and also the mechanism of cellular toxicity of human diseases arising from expansion in polyalanine sequences. The atomic-level structures of alanine tripeptide and tetrapeptide with antiparallel β-sheet structures (AP-Ala3 and AP-Ala4, respectively) together with alanine tripeptide with parallel β-sheet structures (P-Ala3) have been determined, but alanine tetrapeptide with a parallel β-sheet structure (P-Ala4) has not been reported yet. In this article, first, we established the preparation protocol of P-Ala4 from more stable AP-Ala4. Second, complete assignments of the (13)C, (15)N, and (1)H solid-state NMR spectra were performed with (13)C- and (15)N-labeled Ala4 samples using several solid-state NMR techniques. Then, the structural constraints were obtained, for example, the amide proton peaks of P-Ala4 in the (1)H double-quantum magic-angle spinning NMR spectrum were heavily overlapped and observed at about 7.4 ppm, which was a much higher field than that of 8.7-9.1 ppm observed for AP-Ala4, indicating that the intermolecular hydrogen-bond lengths across strands (N-H···O═C) were considerably longer for P-Ala4, that is, 2.21-2.34 Å, than those reported for AP-Ala4, that is, 1.8-1.9 Å. The structural model was proposed for P-Ala4 by NMR results and MD calculations.

  14. Flow-through lipid nanotube arrays for structure-function studies of membrane proteins by solid-state NMR spectroscopy.

    Science.gov (United States)

    Chekmenev, Eduard Y; Gor'kov, Peter L; Cross, Timothy A; Alaouie, Ali M; Smirnov, Alex I

    2006-10-15

    A novel method for studying membrane proteins in a native lipid bilayer environment by solid-state NMR spectroscopy is described and tested. Anodic aluminum oxide (AAO) substrates with flow-through 175 nm wide and 60-mum-long nanopores were employed to form macroscopically aligned peptide-containing lipid bilayers that are fluid and highly hydrated. We demonstrate that the surfaces of both leaflets of such bilayers are fully accessible to aqueous solutes. Thus, high hydration levels as well as pH and desirable ion and/or drug concentrations could be easily maintained and modified as desired in a series of experiments with the same sample. The method allows for membrane protein NMR experiments in a broad pH range that could be extended to as low as 1 and as high as 12 units for a period of up to a few hours and temperatures as high as 70 degrees C without losing the lipid alignment or bilayers from the nanopores. We demonstrate the utility of this method by a solid-state 19.6 T (17)O NMR study of reversible binding effects of mono- and divalent ions on the chemical shift properties of the Leu(10) carbonyl oxygen of transmembrane pore-forming peptide gramicidin A (gA). We further compare the (17)O shifts induced by binding metal ions to the binding of protons in the pH range from 1 to 12 and find a significant difference. This unexpected result points to a difference in mechanisms for ion and proton conduction by the gA pore. We believe that a large number of solid-state NMR-based studies, including structure-function, drug screening, proton exchange, pH, and other titration experiments, will benefit significantly from the method described here.

  15. 43Ca NMR in solid state

    Science.gov (United States)

    Bellot, P.-V.; Trokiner, A.; Zhdanov, Yu.; Yakubovskii, A.

    1998-02-01

    In this paper we show that 43Ca is a suitable NMR probe to study the properties of high-Tc superconducting oxides. In the normal state, we report the temperature and doping dependencies of the spin susceptibility measured by 43Ca NMR. In the superconducting state and more exactly in the mixed state, by analysing 43Ca NMR linewidth, we have studied the magnetic induction distribution due to the presence of vortices and deduced λ, the penetration depth. Dans cet article, on montre que l'isotope 43 du calcium est une bonne sonde RMN pour l'étude des propriétés des oxydes supraconducteurs à haute température. Dans l'état normal, par la détermination du déplacement de la raie, en fonction de la température, on accède à la variation thermique de la susceptibilité de spin. Dans l'état supraconducteur et plus particulièrement dans l'état mixte, la largeur de raie RMN permet d'étudier la distribution d'induction magnétique due à la présence des vortex et de déterminer λ, la longueur de pénétration.

  16. The influence of feedstock and production temperature on biochar carbon chemistry: A solid-state 13C NMR study

    International Nuclear Information System (INIS)

    McBeath, Anna V.; Smernik, Ronald J.; Krull, Evelyn S.; Lehmann, Johannes

    2014-01-01

    Solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy was used to evaluate the carbon chemistry of twenty-six biochars produced from eleven different feedstocks at production temperatures ranging from 350 °C to 600 °C. Carbon-13 NMR spectra were acquired using both cross-polarisation (CP) and direct polarisation (DP) techniques. Overall, the corresponding CP and DP spectra were similar, although aromaticity was slightly higher and observability much higher when DP was used. The relative size and purity of the aromatic ring structures (i.e. aromatic condensation) were also gauged using the ring current technique. Both aromaticity and aromatic condensation increased with increasing production temperature, regardless of the feedstock source. However, there were clear differences in these two measures for biochars produced at the same temperature but from different feedstocks. Based on a relationship previously established in a long-term incubation study between aromatic condensation and the mean residence time (MRT) of biochar, the MRT of the biochars was estimated to range from 1400 years. This study demonstrates how the combination of feedstock composition and production temperature influences the composition of aromatic domains in biochars, which in turn is likely to be related to their recalcitrance and ultimately their carbon sequestration value. -- Highlights: • Sensitive NMR techniques were used to gauge differences in biochar carbon chemistry. • Varying pyrolysis conditions influences biochars recalcitrant properties. • The MRT of contrasting biochars varies considerably from 1400 years

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  18. 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....... Moreover, 13C MAS NMR and infra-red spectroscopy show that PAS did not decompose during synthesis. Large amounts (20-41%) of amorphous aluminum impurities were detected in the structure using 27Al single pulse and 3QMAS NMR spectra, which in combination with 1H single and double quantum experiments also...... 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....

  19. Vortex states of Tl2Ba2CuO6+δ studied via 205Tl NMR at 2 tesla

    International Nuclear Information System (INIS)

    Itoh, Yutaka; Michioka, Chishiro; Yoshimura, Kazuyoshi; Hayashi, Akihiko; Ueda, Yutaka

    2005-01-01

    We report a 205 Tl NMR study of vortex states in an aligned polycrystalline sample of an overdoped high-T c superconductor, Tl 2 Ba 2 CuO 6+δ (Tc - 85 K), at a magnetic field of 2 T along the c axis. We observed an imperfect vortex lattice, so-called Bragg glass, at T=5 K, the coexistence of vortex solid and vortex liquid between 10 and 60 K, and vortex melting between 65 and 85 K. No evidence for local antiferromagnetic ordering at vortex cores was found for our sample. (author)

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    Continuous operation of a polymer photovoltaic device under accelerated conditions for more than 1 year has been demonstrated (8760h at 72 degrees C, 1000Wm(-2), AM 1.5, under vacuum). Formation of hydrogen-bonded networks is proposed to be responsible for the long lifetime and high stability...... observed in photovoltaic devices employing polythiophene substituted with carboxylic-acid moieties under oxygen free conditions. H-1 and C-13 solid-state NMR, IR, and ESR spectroscopy of unmodified and isotopically labeled polythiophenes were studied. Distances between the isotopically labeled carboxylic...

  1. On the structure of amorphous calcium carbonate--a detailed study by solid-state NMR spectroscopy.

    Science.gov (United States)

    Nebel, Holger; Neumann, Markus; Mayer, Christian; Epple, Matthias

    2008-09-01

    The calcium carbonate phases calcite, aragonite, vaterite, monohydrocalcite (calcium carbonate monohydrate), and ikaite (calcium carbonate hexahydrate) were studied by solid-state NMR spectroscopy ( (1)H and (13)C). Further model compounds were sodium hydrogencarbonate, potassium hydrogencarbonate, and calcium hydroxide. With the help of these data, the structure of synthetically prepared additive-free amorphous calcium carbonate (ACC) was analyzed. ACC contains molecular water (as H 2O), a small amount of mobile hydroxide, and no hydrogencarbonate. This supports the concept of ACC as a transient precursor in the formation of calcium carbonate biominerals.

  2. Applications of solid-state Nuclear Magnetic Resonance (NMR) in studies of Portland cements-based materials

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Andersen, Morten Daugaard; Jakobsen, Hans Jørgen

    2007-01-01

    Solid-state NMR spectroscopy represents an important research tool in the characterization of a range of structural properties for cement-based materials. Different approaches of the technique can be used to obtain information on hydration kinetics, mobile and bound water, porosity, and local...... atomic structures. After a short introduction to these NMR techniques, it is exemplified how magic-angle spinning (MAS) NMR can provide quantitative and structural information about specific phases in anhydrous and hydrated Portland cements with main emphasis on the incorporation of Al3+ ions...

  3. Radiation oxidation of polypropylene: A solid-state 13C NMR study using selective isotopic labeling

    International Nuclear Information System (INIS)

    Mowery, Daniel M.; Assink, Roger A.; Derzon, Dora K.; Klamo, Sara B.; Bernstein, Robert; Clough, Roger L.

    2007-01-01

    Polypropylene samples, in which the three different carbon atoms along the chain were selectively labeled with carbon-13, were subjected to radiation under inert and air atmospheres, and to post-irradiation exposure in air at various temperatures. By using solid-state 13 C NMR measurements at room temperature, we have been able to identify and quantify the oxidation products. The isotopic labeling provides insight into chemical reaction mechanisms, since oxidation products can be traced back to their positions of origin on the macromolecule. The major products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. Time-dependent plots of yields of the various oxidation products have been obtained under a wide range of conditions, including the post-irradiation oxidation of a sample at room temperature in air that has been monitored for 2 years. Radiation-oxidation products of polypropylene are contrasted to products measured for 13 C-labeled polyethylene in an earlier investigation: the peroxides formed in irradiated polypropylene are remarkably longer lived, the non-peroxidic products are significantly different, and the overall ratios of oxidation products in polypropylene change relatively little as a function of the extent of oxidation

  4. Combined solid state and solution NMR studies of {alpha},{epsilon}-{sup 15}N labeled bovine rhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Karla; Lehner, Ines [Johann Wolfgang Goethe-Universitaet Frankfurt, Center for Biomolecular Magnetic Resonance (Germany); Dhiman, Harpreet Kaur [University of Pittsburgh School of Medicine, Department of Structural Biology (United States); Richter, Christian; Glaubitz, Clemens; Schwalbe, Harald, E-mail: schwalbe@nmr.uni-frankfurt.de; Klein-Seetharaman, Judith [Johann Wolfgang Goethe-Universitaet Frankfurt, Center for Biomolecular Magnetic Resonance (Germany); Khorana, H. Gobind [Massachusetts Institute of Technology, Departments of Biology and Chemistry (United States)], E-mail: khorana@mit.edu

    2007-04-15

    Rhodopsin is the visual pigment of the vertebrate rod photoreceptor cell and is the only member of the G protein coupled receptor family for which a crystal structure is available. Towards the study of dynamics in rhodopsin, we report NMR-spectroscopic investigations of {alpha},{epsilon}-{sup 15}N-tryptophan labeled rhodopsin in detergent micelles and reconstituted in phospholipids. Using a combination of solid state {sup 13}C,{sup 15}N-REDOR and HETCOR experiments of all possible {sup 13}C'{sub i-1} carbonyl/{sup 15}N{sub i}-tryptophan isotope labeled amide pairs, and H/D exchange {sup 1}H,{sup 15}N-HSQC experiments conducted in solution, we assigned chemical shifts to all five rhodopsin tryptophan backbone {sup 15}N nuclei and partially to their bound protons. {sup 1}H,{sup 15}N chemical shift assignment was achieved for indole side chains of Trp35{sup 1.30} and Trp175{sup 4.65}. {sup 15}N chemical shifts were found to be similar when comparing those obtained in the native like reconstituted lipid environment and those obtained in detergent micelles for all tryptophans except Trp175{sup 4.65} at the membrane interface. The results suggest that the integrated solution and solid state NMR approach presented provides highly complementary information in the study of structure and dynamics of large membrane proteins like rhodopsin.

  5. The structure of phosphate and borosilicate glasses and their structural evolution at high temperatures as studied with solid state NMR spectroscopy: Phase separation, crystallisation and dynamic species exchange

    International Nuclear Information System (INIS)

    Wegner, S.; Van Wullen, L.; Tricot, G.; Tricot, G.

    2010-01-01

    In this contribution we present an in-depth study of the network structure of different phosphate based and borosilicate glasses and its evolution at high temperatures. Employing a range of advanced solid state NMR methodologies, complemented by the results of XPS, the structural motifs on short and intermediate length scales are identified. For the phosphate based glasses, at temperatures above the glass transition temperature Tg, structural relaxation processes and the devitrification of the glasses were monitored in situ employing MAS NMR spectroscopy and X-ray diffraction. Dynamic species exchange involving rapid P-O-P and P-O-Al bond breaking and reforming was observed employing in situ 27 Al and 31 P MAS NMR spectroscopy and could be linked to viscous flow. For the borosilicate glasses, an atomic scale investigation of the phase separation processes was possible in a combined effort of ex situ NMR studies on glass samples with different thermal histories and in situ NMR studies using high temperature MAS NMR spectroscopy including 11 B MAS, 29 Si MAS and in situ 29 Si{ 11 B} REAPDOR NMR spectroscopy. (authors)

  6. sup 3 sup 1 P high resolution solid state NMR studies of phosphoorganic compounds of biological interest

    CERN Document Server

    Potrzebowski, M J; Kazmierski, S

    2001-01-01

    In this review several applications of sup 3 sup 1 P high resolution solid state NMR spectroscopy in structural studies of bioorganic samples is recorded. The problem of pseudopolymorphism of bis[6-O,6'-O-(1,2:3,4diisopropylidene-alpha-D-galactopyranosyl) phosphothionyl] disulfide (1) and application of sup 3 sup 1 P C/MAS experiment to investigate of this phenomenon is discussed. The influence of weak C-H--S intermolecular contacts on molecular packing of 1,6-anhydro-2-O-tosyl-4-S- (5,5-dimethyl-2-thioxa-1,3,2-dioxaphosphophorinan-2-= yl)-beta-D-glucopyranose (2) and S sub P , R sub P diastereomers of deoxyxylothymidyl-3'-O-acetylthymidyl (3',5')-O-(2-cyanoethyl) phosphorothioate (3) and their implication on sup 3 sup 1 P NMR spectra is shown. The final part of review describes the recent progress in structural studies of O-phosphorylated amino acids (serine, threonine, tyrosine), relationship between molecular structure and sup 3 sup 1 P chemical shift parameters delta sub i sub i and influence of hydrogen ...

  7. Myristoylation as a general method for immobilization and alignment of soluble proteins for solid-state NMR structural studies

    International Nuclear Information System (INIS)

    Mesleh, M.F.; Valentine, K.G.; Opella, S.J.; Louis, J.M.; Gronenborn, A.M.

    2003-01-01

    N-terminal myristoylation of the immunoglobulin-binding domain of protein G (GB1) from group G Streptococcus provides the means to bind the protein to aligned phospholipid bilayers for solid-state NMR structural studies. The myristoylated protein is immobilized by its interactions with bilayers, and the sample alignment enables orientationally dependent 15 N chemical shifts and 1 H- 15 N-dipolar couplings to be measured. Spectra calculated for the average solution NMR structure of the protein at various orientations with respect to the magnetic field direction were compared to the experimental spectrum. The best fit identified the orientation of the myristoylated protein on the lipid bilayers, and demonstrated that the protein adopts a similar structure in both its myristoylated and non-myristoylated forms, and that the structure is not grossly distorted by its interaction with the phosholipid bilayer surface or by its location in the restricted aqueous space between bilayer leaflets. The protein is oriented such that its charged sides face the phosphatidylcholine headgroups of the lipids with the single amphiphilic helix running parallel to the bilayer surface

  8. Characterization of phosphate sequestration by a lanthanum modified bentonite clay: A solid-state NMR, EXAFS and PXRD study

    DEFF Research Database (Denmark)

    Dithmer, Line; Lipton, Andrew S; Reitzel, Kasper

    2015-01-01

    Phosphate (Pi) sequestration by a lanthanum (La) exchanged clay mineral (La-Bentonite), which is extensively used in chemical lake restoration, was investigated on the molecular level using a combination of 31P and 139La solid state NMR spectroscopy (SSNMR), extended X-ray absorption spectroscopy...

  9. Epoxy networks reinforced with polyhedral oligomeric silsesquioxanes: structure and segmental dynamics as studied by solid-state NMR

    Czech Academy of Sciences Publication Activity Database

    Brus, Jiří; Urbanová, Martina; Strachota, Adam

    2008-01-01

    Roč. 41, č. 2 (2008), s. 372-386 ISSN 0024-9297 R&D Projects: GA AV ČR IAA400500602 Institutional research plan: CEZ:AV0Z40500505 Keywords : solid-state NMR * polymer networks * polysilsequioxanes Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.407, year: 2008

  10. Solid-state /sup 13/C NMR study of cured resorcinol-formaldehyde resins

    Energy Technology Data Exchange (ETDEWEB)

    Lippmaa, H.; Samoson, A.

    1988-08-01

    The curing process generally follows the pattern observed in the stage of prepolymer formation. Catalysts (NaOH, hexa, Mg(OCOCH/sub 3/)/sub 2/) that have no substantial influence on the isomeric composition of the resorcinol-formaldehyde prepolymers, do not affect the isomeric composition of the cured resins to any significant extent either. Isomeric composition of the cured resins depends mostly on the presence of water during the curing process, necessary for depolymerisation of the added paraformaldehyde. Curing in the melt leads to enhanced 2-substitution in the 1,3-dihydroxybenzene rings. In the /sup 13/C NMR spectra of cured powdered samples, the tendency of 5-methylresorcinol to form oligomers with a higher degree of 2-substitution than resorcinol is clearly apparent. Polycondensation process continues in the powdered resins after initial curing until complete consumption of all formaldehyde. Curing of phenol-formaldehyde resols proceeds through intermediate dimethylene ether formation.

  11. Water interactions with varying molecular states of bovine casein: 2H NMR relaxation studies

    International Nuclear Information System (INIS)

    Kumosinski, T.F.; Pessen, H.; Prestrelski, S.J.; Farrell, H.M. Jr.

    1987-01-01

    The caseins occur in milk as spherical colloidal complexes of protein and salts with an average diameter of 1200 A, the casein micelles. Removal of Ca2+ is thought to result in their dissociation into smaller protein complexes stabilized by hydrophobic interactions and called submicelles. Whether these submicelles actually occur within the micelles as discrete particles interconnected by calcium phosphate salt bridges has been the subject of much controversy. A variety of physical measurements have shown that casein micelles contain an inordinately high amount of trapped water (2 to 7 g H 2 O/g protein). With this in mind it was of interest to determine if NMR relaxation measurements could detect the presence of this trapped water within the micelles, and to evaluate whether it is a continuum with picosecond correlation times or is associated in part with discrete submicellar structures with nanosecond motions. For this purpose the variations in 2 H NMR longitudinal and transverse relaxation rates of water with protein concentration were determined for bovine casein at various temperatures, under both submicellar and micellar conditions. D 2 O was used instead of H 2 O to eliminate cross-relaxation effects. From the protein concentration dependence of the relaxation rates, the second virial coefficient of the protein was obtained by nonlinear regression analysis. Using either an isotropic tumbling or an intermediate asymmetry model, degrees of hydration, v, and correlation times, tau c, were calculated for the caseins; from the latter parameter the Stokes radius, r, was obtained. Next, estimates of molecular weights were obtained from r and the partial specific volume. Values were in the range of those published from other methodologies for the submicelles

  12. Solution and solid state NMR studies of the structure and dynamics of C60 and C70

    International Nuclear Information System (INIS)

    Johnson, R.D.; Yannoni, C.S.; Salem, J.; Meijer, G.; Bethune, D.S.

    1991-01-01

    This paper investigates the structure and dynamics of C 60 and C 70 with 13 C NMR spectroscopy. In solution, high-resolution spectra reveal that C 60 has a single resonance at 143 ppm, indicating a strained, aromatic system with high symmetry. This is strong evidence for a C 60 soccer ball geometry. A 2D NMR INADEQUATE experiment on 13 C-enriched C 70 reveals the bonding connectivity to be a linear string, in firm support of the proposed rugby ball structure with D 5h symmetry, and furnishes resonance assignments. Solid state NMR spectra of C 60 at ambient temperatures yield a narrow resonance, indicative of rapid molecular reorientation. Variable temperature T 1 measurements show that the rotational correlation time is ∼ 10 - 9 s at 230 K. At 77 K, this time increases to more than 1 ms, and the 13 C NMR spectrum of C 60 is a powder pattern due to chemical shift anisotropy (tensor components 220, 186, 40 ppm). At intermediate temperatures a narrow peak is superimposed on the powder pattern, suggesting a distribution of barriers to molecular motion in the sample, or the presence of an additional phase in the solid state. A Carr-Purcell dipolar experiment on C 60 in the solid state allows the first precise determination of the C 60 bond lengths: 1.45 and 1.40 Angstrom

  13. NMR study on the low-temperature state of LaMn{sub 4}Al{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Muro, Y. [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan)]. E-mail: rk04j052@stkt.u-hyogo.ac.jp; Nakamura, H. [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan); Kohara, T. [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan)

    2007-03-15

    The ground state of the quasi-one-dimensional itinerant electron magnet LaMn{sub 4}Al{sub 8} with strong electron correlation has been investigated by NMR. The presence of weak and broad zero-field {sup 55}Mn resonance, corresponding to internal field of 8-11T, indicates slowing down of spins partially released from the spin-singlet-like state in the spin chains.

  14. Sparse "1"3C labelling for solid-state NMR studies of P. pastoris expressed eukaryotic seven-transmembrane proteins

    International Nuclear Information System (INIS)

    Liu, Jing; Liu, Chang; Fan, Ying; Munro, Rachel A.; Ladizhansky, Vladimir; Brown, Leonid S.; Wang, Shenlin

    2016-01-01

    We demonstrate a novel sparse "1"3C labelling approach for methylotrophic yeast P. pastoris expression system, towards solid-state NMR studies of eukaryotic membrane proteins. The labelling scheme was achieved by co-utilizing natural abundance methanol and specifically "1"3C labelled glycerol as carbon sources in the expression medium. This strategy improves the spectral resolution by 1.5 fold, displays site-specific labelling patterns, and has advantages for collecting long-range distance restraints for structure determination of large eukaryotic membrane proteins by solid-state NMR.

  15. Amorphous surface layer versus transient amorphous precursor phase in bone - A case study investigated by solid-state NMR spectroscopy.

    Science.gov (United States)

    Von Euw, Stanislas; Ajili, Widad; Chan-Chang, Tsou-Hsi-Camille; Delices, Annette; Laurent, Guillaume; Babonneau, Florence; Nassif, Nadine; Azaïs, Thierry

    2017-09-01

    The presence of an amorphous surface layer that coats a crystalline core has been proposed for many biominerals, including bone mineral. In parallel, transient amorphous precursor phases have been proposed in various biomineralization processes, including bone biomineralization. Here we propose a methodology to investigate the origin of these amorphous environments taking the bone tissue as a key example. This study relies on the investigation of a bone tissue sample and its comparison with synthetic calcium phosphate samples, including a stoichiometric apatite, an amorphous calcium phosphate sample, and two different biomimetic apatites. To reveal if the amorphous environments in bone originate from an amorphous surface layer or a transient amorphous precursor phase, a combined solid-state nuclear magnetic resonance (NMR) experiment has been used. The latter consists of a double cross polarization 1 H→ 31 P→ 1 H pulse sequence followed by a 1 H magnetization exchange pulse sequence. The presence of an amorphous surface layer has been investigated through the study of the biomimetic apatites; while the presence of a transient amorphous precursor phase in the form of amorphous calcium phosphate particles has been mimicked with the help of a physical mixture of stoichiometric apatite and amorphous calcium phosphate. The NMR results show that the amorphous and the crystalline environments detected in our bone tissue sample belong to the same particle. The presence of an amorphous surface layer that coats the apatitic core of bone apatite particles has been unambiguously confirmed, and it is certain that this amorphous surface layer has strong implication on bone tissue biogenesis and regeneration. Questions still persist on the structural organization of bone and biomimetic apatites. The existing model proposes a core/shell structure, with an amorphous surface layer coating a crystalline bulk. The accuracy of this model is still debated because amorphous calcium

  16. Host-guest interaction of styrene and ethylbenzene in MIL-53 studied by solid-state NMR.

    Science.gov (United States)

    Li, Shenhui; Li, Jing; Tang, Jing; Deng, Feng

    Solid-state NMR was utilized to explore the host-guest interaction between adsorbate and adsorbent at atomic level to understand the separation mechanism of styrene (St) and ethylbenzene (EB) in MIL-53(Al). 13 C- 27 Al double-resonance NMR experiments revealed that the host-guest interaction between St and MIL-53 was much stronger than that of EB adsorption. In addition, 13 C DIPSHIFT experiments suggested that the adsorbed St was less mobile than EB confined inside the MIL-53 pore. Furthermore, the host-guest interaction model between St, EB and MIL-53 was established on the basis of the spatial proximities information extracted from 2D 1 H- 1 H homo-nuclear correlation NMR experiments. According to the experimental observation from solid-state NMR, it was found that the presence of π-π interaction between St and MIL-53 resulted in the stronger host-guest interaction and less mobility of St. This work provides direct experimental evidence for understanding the separation mechanism of St and EB using MIL-53 as an adsorbent. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Solid-state NMR study of stereocomplexes formed by enantiomeric star-shaped PEG-PLA copolymers in water

    NARCIS (Netherlands)

    Calucci, Lucia; Forte, Claudia; Buwalda, S.J.; Dijkstra, Pieter J.

    2011-01-01

    Solid-state NMR was applied to samples obtained by freeze-drying hydrogels of 1:1 (PEG65-NHCO-PLLA13)8/(PEG65-NHCO-PDLA13)8 or (PEG65-NHCO-PDLA13)8 only star block copolymers (where PEG, PLLA, and PDLA stand for poly(ethylene glycol), poly(l-lactide), and poly(d-lactide), respectively) in order to

  18. Study concerning the compatibility of the mixture of nylon-6 and poly(propylene oxide) through solid state NMR

    International Nuclear Information System (INIS)

    Tavares, Maria I.B.; Costa, D.A.; Menezes, Sonia M.C.

    1993-01-01

    NMR has been frequently used for the determination of polymers compatibility. The utilization of the simple pulse technique together with the contact time variation technique has been enabling the evaluation of the compatibility of polymeric systems. This work presents the study of the behaviour of the mixture composed by nylon-6 with poly(propylene oxide) using these techniques. Results are presented

  19. 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.

  20. Solid state NMR of isotope labelled murine fur: a powerful tool to study atomic level keratin structure and treatment effects

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Wai Ching Veronica; Narkevicius, Aurimas; Chow, Wing Ying; Reid, David G.; Rajan, Rakesh [University of Cambridge, Department of Chemistry (United Kingdom); Brooks, Roger A. [University of Cambridge, Department of Trauma and Orthopaedic Surgery, Addenbrooke’s Hospital (United Kingdom); Green, Maggie [University of Cambridge, Central Biomedical Resources, School of Clinical Medicine (United Kingdom); Duer, Melinda J., E-mail: mjd13@cam.ac.uk [University of Cambridge, Department of Chemistry (United Kingdom)

    2016-10-15

    We have prepared mouse fur extensively {sup 13}C,{sup 15}N-labelled in all amino acid types enabling application of 2D solid state NMR techniques which establish covalent and spatial proximities within, and in favorable cases between, residues. {sup 13}C double quantum–single quantum correlation and proton driven spin diffusion techniques are particularly useful for resolving certain amino acid types. Unlike 1D experiments on isotopically normal material, the 2D methods allow the chemical shifts of entire spin systems of numerous residue types to be determined, particularly those with one or more distinctively shifted atoms such as Gly, Ser, Thr, Tyr, Phe, Val, Leu, Ile and Pro. Also the partial resolution of the amide signals into two signal envelopes comprising of α-helical, and β-sheet/random coil components, enables resolution of otherwise overlapped α-carbon signals into two distinct cross peak families corresponding to these respective secondary structural regions. The increase in resolution conferred by extensive labelling offers new opportunities to study the chemical fate and structural environments of specific atom and amino acid types under the influence of commercial processes, and therapeutic or cosmetic treatments.

  1. Liquid-Liquid Phase Separation in Model Nuclear Waste Glasses: A Solid-State Double-Resonance NMR Study

    Energy Technology Data Exchange (ETDEWEB)

    Martineau, Ch.; Michaelis, V.K.; Kroeker, S. [Univ Manitoba, Dept Chem, Winnipeg, MB R3T 2N2 (Canada); Schuller, S. [CEA Valrho Marcoule, LDMC, SECM, DTCD, DEN, F-30207 Bagnols Sur Ceze (France)

    2010-07-01

    Double-resonance nuclear magnetic resonance (NMR) techniques are used in addition to single-resonance NMR experiments to probe the degree of mixing between network-forming cations Si and B, along with the modifier cations Cs{sup +} and Na{sup +} in two molybdenum-bearing model nuclear waste glasses. The double-resonance experiments involving {sup 29}Si in natural abundance are made possible by the implementation of a CPMG pulse-train during the acquisition period of the usual REDOR experiments. For the glass with lower Mo content, the NMR results show a high degree of Si-B mixing, as well as an homogeneous distribution of the cations within the borosilicate network, characteristic of a non-phase-separated glass. For the higher-Mo glass, a decrease of B-Si(Q{sup 4}) mixing is observed, indicating phase separation. {sup 23}Na and {sup 133}Cs NMR results show that although the Cs{sup +} cations, which do not seem to be influenced by the molybdenum content, are spread within the borate network, there is a clustering of the Na{sup +} cations, very likely around the molybdate units. The segregation of a Mo-rich region with Na{sup +} cations appears to shift the bulk borosilicate glass composition toward the metastable liquid liquid immiscibility region and induce additional phase separation. Although no crystallization is observed in the present case, this liquid liquid phase separation is likely to be the first stage of crystallization that can occur at higher Mo loadings or be driven by heat treatment. From this study emerges a consistent picture of the nature and extent of such phase separation phenomena in Mo-bearing glasses, and demonstrates the potential of double-resonance NMR methods for the investigation of phase separation in amorphous materials. (authors)

  2. PVT Degradation Studies: NMR Analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-06

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

  3. Experimental solid state NMR of gas hydrates : problems and solutions

    Energy Technology Data Exchange (ETDEWEB)

    Moudrakovski, I.; Lu, H.; Ripmeester, J. [National Research Council of Canada, Ottawa, ON (Canada). Steacie Inst. for Molecular Sciences; Kumar, R.; Susilo, R. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Luzi, M. [GeoForschungsZentrum Potsdam, Potsdam (Germany)

    2008-07-01

    Solid State NMR is a suitable spectroscopic technique for hydrate research for several reasons, including its capability to distinguish between different structural types of hydrates, its quantitative nature and potential for both in-situ and time resolved experiments. This study illustrated the applications of solid state NMR for compositional and structural studies of clathrate hydrates, with particular emphasis on experimental techniques and potential ways to overcome technical difficulties. In order to use the method to its full capacity, some instrumental developments are needed to adapt it to the specific experimental requirements of hydrate studies, such as very low temperatures and high pressures. This presentation discussed the quantification of the Carbon-13 spectra with examples from natural and synthetic hydrates prepared from multi-component mixtures of hydrocarbons. The main approach used for the first two examples was Carbon-13 NMR with Magic Angle Spinning (MAS) at -100 degrees C. The detailed characterization of mixed hydrogen hydrates required low temperature hydrogen MAS. The quantification problems encountered during these experiments were also discussed. The purpose of these recent experimental developments was to prompt wider application of Solid State NMR in hydrate research. NMR proved to be a viable method for analyzing the composition and structure of multi-component mixed gas hydrates; characterizing natural gas hydrates; and, evaluating the formation conditions and properties of mixed hydrogen hydrates. The limitations of the method were highlighted and sensible choices of experimental conditions and techniques that ensure accurate results were discussed. 34 refs., 10 figs.

  4. Application of solid state NMR for the study of surface bound species and fossil fuels

    Energy Technology Data Exchange (ETDEWEB)

    Althaus, Stacey [Iowa State Univ., Ames, IA (United States)

    2014-01-01

    In this study, stimulated echo with pulsed field gradients was used to measure the diffusion of two different solvents, water and hexane, in AP-MSN-2.7 and AP-MSN-3.7. The resulting data were then fit using two different methods. Based on these fits, the diffusion of hexane in AP-MSN-2.7 was shown to be slower than in the larger pores. This agrees well with our studies of catalytic activity, which show an increase in the reaction rate with the increase in pore size. Thus, both substrate inhibition and diffusion played a role in the decreased efficiency of the APMSN with small pore sizes.

  5. NMR study of hydride systems

    International Nuclear Information System (INIS)

    Peretz, M.

    1980-02-01

    The hydrides of thorium (ThH 2 , Th 4 H 15 and Th 4 D 15 ) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x)) 2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th 4 H 15 than in ThH 2 ; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th 4 H 15 ; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

  6. Uniform isotope labeling of a eukaryotic seven-transmembrane helical protein in yeast enables high-resolution solid-state NMR studies in the lipid environment

    International Nuclear Information System (INIS)

    Fan Ying; Shi Lichi; Ladizhansky, Vladimir; Brown, Leonid S.

    2011-01-01

    Overexpression of isotope-labeled multi-spanning eukaryotic membrane proteins for structural NMR studies is often challenging. On the one hand, difficulties with achieving proper folding, membrane insertion, and native-like post-translational modifications frequently disqualify bacterial expression systems. On the other hand, eukaryotic cell cultures can be prohibitively expensive. One of the viable alternatives, successfully used for producing proteins for solution NMR studies, is yeast expression systems, particularly Pichia pastoris. We report on successful implementation and optimization of isotope labeling protocols, previously used for soluble secreted proteins, to produce homogeneous samples of a eukaryotic seven-transmembrane helical protein, rhodopsin from Leptosphaeria maculans. Even in shake-flask cultures, yields exceeded 5 mg of purified uniformly 13 C, 15 N-labeled protein per liter of culture. The protein was stable (at least several weeks at 5°C) and functionally active upon reconstitution into lipid membranes at high protein-to-lipid ratio required for solid-state NMR. The samples gave high-resolution 13 C and 15 N solid-state magic angle spinning NMR spectra, amenable to a detailed structural analysis. We believe that similar protocols can be adopted for challenging mammalian targets, which often resist characterization by other structural methods.

  7. Proton transfer and hydrogen bonding in the organic solid state: a combined XRD/XPS/ssNMR study of 17 organic acid-base complexes.

    Science.gov (United States)

    Stevens, Joanna S; Byard, Stephen J; Seaton, Colin C; Sadiq, Ghazala; Davey, Roger J; Schroeder, Sven L M

    2014-01-21

    The properties of nitrogen centres acting either as hydrogen-bond or Brønsted acceptors in solid molecular acid-base complexes have been probed by N 1s X-ray photoelectron spectroscopy (XPS) as well as (15)N solid-state nuclear magnetic resonance (ssNMR) spectroscopy and are interpreted with reference to local crystallographic structure information provided by X-ray diffraction (XRD). We have previously shown that the strong chemical shift of the N 1s binding energy associated with the protonation of nitrogen centres unequivocally distinguishes protonated (salt) from hydrogen-bonded (co-crystal) nitrogen species. This result is further supported by significant ssNMR shifts to low frequency, which occur with proton transfer from the acid to the base component. Generally, only minor chemical shifts occur upon co-crystal formation, unless a strong hydrogen bond is formed. CASTEP density functional theory (DFT) calculations of (15)N ssNMR isotropic chemical shifts correlate well with the experimental data, confirming that computational predictions of H-bond strengths and associated ssNMR chemical shifts allow the identification of salt and co-crystal structures (NMR crystallography). The excellent agreement between the conclusions drawn by XPS and the combined CASTEP/ssNMR investigations opens up a reliable avenue for local structure characterization in molecular systems even in the absence of crystal structure information, for example for non-crystalline or amorphous matter. The range of 17 different systems investigated in this study demonstrates the generic nature of this approach, which will be applicable to many other molecular materials in organic, physical, and materials chemistry.

  8. Advances in solid-state NMR of cellulose.

    Science.gov (United States)

    Foston, Marcus

    2014-06-01

    Nuclear magnetic resonance (NMR) spectroscopy is a well-established analytical and enabling technology in biofuel research. Over the past few decades, lignocellulosic biomass and its conversion to supplement or displace non-renewable feedstocks has attracted increasing interest. The application of solid-state NMR spectroscopy has long been seen as an important tool in the study of cellulose and lignocellulose structure, biosynthesis, and deconstruction, especially considering the limited number of effective solvent systems and the significance of plant cell wall three-dimensional microstructure and component interaction to conversion yield and rate profiles. This article reviews common and recent applications of solid-state NMR spectroscopy methods that provide insight into the structural and dynamic processes of cellulose that control bulk properties and biofuel conversion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. NMR spectroscopic studies of a TAT-derived model peptide in imidazolium-based ILs: influence on chemical shifts and the cis/trans equilibrium state.

    Science.gov (United States)

    Wiedemann, Christoph; Ohlenschläger, Oliver; Mrestani-Klaus, Carmen; Bordusa, Frank

    2017-09-13

    NMR spectroscopy was used to study systematically the impact of imidazolium-based ionic liquid (IL) solutions on a TAT-derived model peptide containing Xaa-Pro peptide bonds. The selected IL anions cover a wide range of the Hofmeister series of ions. Based on highly resolved one- and two-dimensional NMR spectra individual 1 H and 13 C peptide chemical shift differences were analysed and a classification of IL anions according to the Hofmeister series was derived. The observed chemical shift changes indicate significant interactions between the peptide and the ILs. In addition, we examined the impact of different ILs towards the cis/trans equilibrium state of the Xaa-Pro peptide bonds. In this context, the IL cations appear to be of exceptional importance for inducing an alteration of the native cis/trans equilibrium state of Xaa-Pro bonds in favour of the trans-isomers.

  10. Curing reactions of bismaleimide resins catalyzed by triphenylphosphine. High resolution solid-state 13C NMR study

    International Nuclear Information System (INIS)

    Shibahara, Sumio; Enoki, Takashi; Yamamoto, Takahisa; Motoyoshiya, Jiro; Hayashi, Sadao.

    1996-01-01

    The curing reactions of bismaleimide resins consisted of N,N'-4,4'-diphenylmethanebismaleimide (BMI) and o,o'-diallylbisphenol-A (DABA) in the presence of triphenylphosphine (TPP) as a catalyst were investigated. DSC measurements showed that the catalytic effect of TPP on the curing reaction of BMI was more in the presence of DABA than in its absence. In order to explore this curing reaction, N-phenylmaleimide (PMI) and o-allylphenol (AP) were selected as model compounds. The products of the PMI/TPP system were oligomers and polymers of PMI, whereas the main product of the PMI/AP/TPP system was the PMI trimer which had the five-membered ring formed via the phosphonium ylide intermediate. In these model reactions, 13 C NMR was found to be useful to distinguish between trimerization and polymerization of PMI. On the basis of the results of the model reactions, the curing reactions of bismaleimide resins were investigated by high resolution solid state 13 C NMR techniques. In the BMI/TPP system, maleimides polymerize above 175degC, but the polymerization does not proceed at 120degC. On the other hand, maleimides trimerize above 120degC in the presence of DABA and TPP. The mechanism of the trimerization is briefly discussed. (author)

  11. Solid-state NMR spectroscopy on complex biomolecules

    NARCIS (Netherlands)

    Renault, M.A.M.; Cukkemane, A.A.; Baldus, M.

    2010-01-01

    Biomolecular applications of NMR spectroscopy are often merely associated with soluble molecules or magnetic resonance imaging. However, since the late 1970s, solid-state NMR (ssNMR) spectroscopy has demonstrated its ability to provide atomic-level insight into complex biomolecular systems ranging

  12. 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...

  13. A Solid-State Deuterium NMR and SFG Study of the Side Chain Dynamics of Peptides Adsorbed onto Surfaces

    Science.gov (United States)

    Breen, Nicholas F.; Weidner, Tobias; Li, Kun; Castner, David G.; Drobny, Gary P.

    2011-01-01

    The artificial amphiphilic peptide LKα14 adopts a helical structure at interfaces, with opposite orientation of its leucine (L, hydrophobic) and lysine (K, hydrophilic) side chains. When adsorbed onto surfaces, different residue side chains necessarily have different proximities to the surface, depending on both their position in the helix and the composition of the surface itself. Deuterating the individual leucine residues (isopropyl-d7) permits the use of solid-state deuterium NMR as a site-specific probe of side chain dynamics. In conjunction with SFG as a probe of the peptide binding face, we demonstrate that the mobility of specific leucine side chains at the interface is quantifiable in terms of their surface proximity. PMID:19764755

  14. Solid-State NMR and DFT Studies on the Formation of Well-Defined Silica-Supported Tantallaaziridines: From Synthesis to Catalytic Application

    KAUST Repository

    Hamzaoui, Bilel; Pelletier, Jeremie; Abou-Hamad, Edy; Chen, Yin; El Eter, Mohamad; Chermak, Edrisse; Cavallo, Luigi; Basset, Jean-Marie

    2016-01-01

    spectroscopy, elemental analysis, and 1H,13C HETCOR and DQ TQ solid-state (SS) NMR spectroscopy. The formation mechanism, by β-H abstraction, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C-H activation of the dimethylamide

  15. Study of water dynamics in the soaking, steaming, and solid-state fermentation of glutinous rice by LF-NMR: a novel monitoring approach.

    Science.gov (United States)

    Li, Teng; Tu, Chuanhai; Rui, Xin; Gao, Yangwen; Li, Wei; Wang, Kun; Xiao, Yu; Dong, Mingsheng

    2015-04-01

    Solid-state fermentation (SSF) of starchy grain is a traditional technique for food and alcoholic beverage production in East Asia. In the present study, low-field nuclear magnetic resonance (LF-NMR) was introduced for the elucidation of water dynamics and microstructure alternations during the soaking, steaming, and SSF of glutinous rice as a rapid real-time monitoring method. Three different proton fractions with different mobilities were identified based on the degree of interaction between biopolymers and water. Soaking and steaming significantly changed the proton distribution of the sample. The different phases of SSF were reflected by the T2 parameters. In addition, the variations in the T2 parameters were explained by the microstructure changes of rice induced by SSF. The fermentation time and T2 parameters were sigmoidally correlated. Thus, LF-NMR may be an effective real-time monitoring method for SSF in starch systems.

  16. Tautomerism of pyrazolinones in the solid state: the case of 1-aryl-3-methyl-3-pyrazolin-5-ones. An X-ray and CPMAS NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Foces-Foces, C. [Departamento de Cristalografia. Instituto de Quimica Fisica. Rocasolano. Madrid (Spain); Fontenas, Ch.; Elguero, J. [Instituto de Quimica Medica. Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales. CSIC. Madrid (Spain)

    1997-10-01

    The tautomerism of pyrazolines in solution is one of the best-studied cases of tautomerism. Although there are many X-ray structures of these compounds, no systematic study of their tautomerism in the solid state has been carried out. In this paper we present the results obtained by X-ray crystallography and ``13 C CPMAS NMR on two related compounds, 1-phenyl-and 1-p-bromo phenyl-3-methyl pyrazoline, as well as the result of a search in the CSD. Some general conclusions about the tautomerism of pyrazolines have been drawn. (Author) 22 refs.

  17. Solid State NMR Characterization of Complex Metal Hydrides systems for Hydrogen Storage Applications

    Directory of Open Access Journals (Sweden)

    Son-Jong Hwang

    2011-12-01

    Full Text Available Solid state NMR is widely applied in studies of solid state chemistries for hydrogen storage reactions. Use of 11B MAS NMR in studies of metal borohydrides (BH4 is mainly focused, revisiting the issue of dodecaborane formation and observation of 11B{1H} Nuclear Overhauser Effect.

  18. NMR imaging studies of coal

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-06-01

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

  19. A solid-state NMR and DFT study of compositional modulations in AlxGa1-xAs

    NARCIS (Netherlands)

    Knijn, Paulus J.; Bentum, P. Jan M. van; Eck, Ernst R.H. van; Fang, Changming; Grimminck, Dennis L.A.G.; Groot, Robert A. de; Havenith, Remco W.A.; Marsman, Martijn; Meerts, W. Leo; Wijs, Gilles A. de; Kentgens, Arno P.M.

    2010-01-01

    We have conducted 75As and 69Ga Nuclear Magnetic Resonance (NMR) experiments to investigate order/disorder in AlxGa1-xAs lift-off films with x ~ 0.297 and 0.489. We were able to identify all possible As(AlnGa4-n) sites with n = 0–4 coordinations in 75As NMR spectra using spin-echo experiments at

  20. 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.

  1. NMR Studies of Polymer Nanocomposites

    National Research Council Canada - National Science Library

    Greenbaum, Steve

    2001-01-01

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

  2. Demonstration of Lignin-to-Peroxidase Direct Electron Transfer: A TRANSIENT-STATE KINETICS, DIRECTED MUTAGENESIS, EPR, AND NMR STUDY.

    Science.gov (United States)

    Sáez-Jiménez, Verónica; Baratto, Maria Camilla; Pogni, Rebecca; Rencoret, Jorge; Gutiérrez, Ana; Santos, José Ignacio; Martínez, Angel T; Ruiz-Dueñas, Francisco Javier

    2015-09-18

    Versatile peroxidase (VP) is a high redox-potential peroxidase of biotechnological interest that is able to oxidize phenolic and non-phenolic aromatics, Mn(2+), and different dyes. The ability of VP from Pleurotus eryngii to oxidize water-soluble lignins (softwood and hardwood lignosulfonates) is demonstrated here by a combination of directed mutagenesis and spectroscopic techniques, among others. In addition, direct electron transfer between the peroxidase and the lignin macromolecule was kinetically characterized using stopped-flow spectrophotometry. VP variants were used to show that this reaction strongly depends on the presence of a solvent-exposed tryptophan residue (Trp-164). Moreover, the tryptophanyl radical detected by EPR spectroscopy of H2O2-activated VP (being absent from the W164S variant) was identified as catalytically active because it was reduced during lignosulfonate oxidation, resulting in the appearance of a lignin radical. The decrease of lignin fluorescence (excitation at 355 nm/emission at 400 nm) during VP treatment under steady-state conditions was accompanied by a decrease of the lignin (aromatic nuclei and side chains) signals in one-dimensional and two-dimensional NMR spectra, confirming the ligninolytic capabilities of the enzyme. Simultaneously, size-exclusion chromatography showed an increase of the molecular mass of the modified residual lignin, especially for the (low molecular mass) hardwood lignosulfonate, revealing that the oxidation products tend to recondense during the VP treatment. Finally, mutagenesis of selected residues neighboring Trp-164 resulted in improved apparent second-order rate constants for lignosulfonate reactions, revealing that changes in its protein environment (modifying the net negative charge and/or substrate accessibility/binding) can modulate the reactivity of the catalytic tryptophan. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. NMR studies of the structure of glasses

    International Nuclear Information System (INIS)

    Bray, P.J.; Gravina, S.J.; Stallworth, P.E.; Szu, S.P.; Jianhui Zhong

    1988-01-01

    Earlier continuous wave (CW) NMR studies of chemical bonding and structure in glasses are summarized. Examples are given of this use of the quadrupolar interaction and chemical shift to obtain structural information. New NMR data and analyses are presented for alkali borate and gallate glasses. Extensions to other elements (e.g. molybdenum, lanthanum) are suggested. 44 refs. (author)

  4. 2D NMR studies of biomolecules

    International Nuclear Information System (INIS)

    Lamerichs, R.M.J.N.

    1989-01-01

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

  5. NMR study of Albemoschus esculentus characterization

    International Nuclear Information System (INIS)

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

    2001-01-01

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

  6. NMR studies of metallic tin confined within porous matrices

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Hodgkinson, P.

    2013-01-01

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

  8. 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

  9. A Solid-State NMR Experiment: Analysis of Local Structural Environments in Phosphate Glasses

    Science.gov (United States)

    Anderson, Stanley E.; Saiki, David; Eckert, Hellmut; Meise-Gresch, Karin

    2004-01-01

    An experiment that can be used to directly study the local chemical environments of phosphorus in solid amorphous materials is demonstrated. The experiment aims at familiarizing the students of chemistry with the principles of solid-state NMR, by having them synthesize a simple phosphate glass, and making them observe the (super 31)P NMR spectrum,…

  10. NMR and optical studies of piezoelectric polymers

    International Nuclear Information System (INIS)

    Schmidt, V.H.; Tuthill, G.F.

    1993-01-01

    Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF 2 ) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done

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

    DEFF Research Database (Denmark)

    Malmendal, Anders; Underhaug, Jarl; Otzen, Daniel

    2010-01-01

    To obtain insight into the functions of proteins and their specific roles, it is important to establish efficient procedures for exploring the states that encapsulate their conformational space. Global Protein folding State mapping by multivariate NMR (GPS NMR) is a powerful high-throughput method......-lactalbumin in the presence of the anionic surfactant sodium dodecyl sulfate, SDS, and compare these with other surfactants, acid, denaturants and heat....

  12. Solid-state NMR covariance of homonuclear correlation spectra.

    Science.gov (United States)

    Hu, Bingwen; Amoureux, Jean-Paul; Trebosc, Julien; Deschamps, Michael; Tricot, Gregory

    2008-04-07

    Direct covariance NMR spectroscopy, which does not involve a Fourier transformation along the indirect dimension, is demonstrated to obtain homonuclear correlation two-dimensional (2D) spectra in the solid state. In contrast to the usual 2D Fourier transform (2D-FT) NMR, in a 2D covariance (2D-Cov) spectrum the spectral resolution in the indirect dimension is determined by the resolution along the detection dimension, thereby largely reducing the time-consuming indirect sampling requirement. The covariance method does not need any separate phase correction or apodization along the indirect dimension because it uses those applied in the detection dimension. We compare in detail the specifications obtained with 2D-FT and 2D-Cov, for narrow and broad resonances. The efficiency of the covariance data treatment is demonstrated in organic and inorganic samples that are both well crystallized and amorphous, for spin -1/2 nuclei with 13C, 29Si, and 31P through-space or through-bond homonuclear 2D correlation spectra. In all cases, the experimental time has been reduced by at least a factor of 10, without any loss of resolution and signal to noise ratio, with respect to what is necessary with the 2D-FT NMR. According to this method, we have been able to study the silicate network of glasses by 2D NMR within reasonable experimental time despite the very long relaxation time of the 29Si nucleus. The main limitation of the 2D-Cov data treatment is related to the introduction of autocorrelated peaks onto the diagonal, which does not represent any actual connectivity.

  13. Study of the molecular mobility of methyl-methacrylate and methacrylic acid copolymers by solid state NMR

    International Nuclear Information System (INIS)

    Tavares, Maria Ines B.; Mansur, Claudia R.E.; Monteiro, Elisabeth E.C.

    1997-01-01

    Several methyl-methacrylate/methacrylic acid copolymers were prepared in the presence of concentrated nitric acid. The obtained copolymers were characterized by molecular weigh determination and hydrolization degree. The molecular mobility of these copolymers was studied by solid state nuclear magnetic resonance. Results are presented

  14. NMR studies of cerebral metabolism in vivo

    International Nuclear Information System (INIS)

    Prichard, J.W.

    1986-01-01

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

  15. A software framework for analysing solid-state MAS NMR data

    International Nuclear Information System (INIS)

    Stevens, Tim J.; Fogh, Rasmus H.; Boucher, Wayne; Higman, Victoria A.; Eisenmenger, Frank; Bardiaux, Benjamin; Rossum, Barth-Jan van; Oschkinat, Hartmut; Laue, Ernest D.

    2011-01-01

    Solid-state magic-angle-spinning (MAS) NMR of proteins has undergone many rapid methodological developments in recent years, enabling detailed studies of protein structure, function and dynamics. Software development, however, has not kept pace with these advances and data analysis is mostly performed using tools developed for solution NMR which do not directly address solid-state specific issues. Here we present additions to the CcpNmr Analysis software package which enable easier identification of spinning side bands, straightforward analysis of double quantum spectra, automatic consideration of non-uniform labelling schemes, as well as extension of other existing features to the needs of solid-state MAS data. To underpin this, we have updated and extended the CCPN data model and experiment descriptions to include transfer types and nomenclature appropriate for solid-state NMR experiments, as well as a set of experiment prototypes covering the experiments commonly employed by solid-sate MAS protein NMR spectroscopists. This work not only improves solid-state MAS NMR data analysis but provides a platform for anyone who uses the CCPN data model for programming, data transfer, or data archival involving solid-state MAS NMR data.

  16. Adiabatic fast passage application in solid state NMR study of cross relaxation and molecular dynamics in heteronuclear systems.

    Science.gov (United States)

    Baranowski, M; Woźniak-Braszak, A; Jurga, K

    2016-01-01

    The paper presents the benefits of using fast adiabatic passage for the study of molecular dynamics in the solid state heteronuclear systems in the laboratory frame. A homemade pulse spectrometer operating at the frequency of 30.2MHz and 28.411MHz for protons and fluorines, respectively, has been enhanced with microcontroller direct digital synthesizer DDS controller [1-4]. This work briefly describes how to construct a low-cost and easy-to-assemble adiabatic extension set for homemade and commercial spectrometers based on recently very popular Arduino shields. The described set was designed for fast adiabatic generation. Timing and synchronization problems are discussed. The cross-relaxation experiments with different initial states of the two spin systems have been performed. Contrary to our previous work [5] where the steady-state NOE experiments were conducted now proton spins (1)H are polarized in the magnetic field B0 while fluorine spins (19)F are perturbed by selective saturation for a short time and then the system is allowed to evolve for a period in the absence of a saturating field. The adiabatic passage application leads to a reversal of magnetization of fluorine spins and increases the amplitude of the signal. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Ground state properties of neutron-rich Mg isotopes the "island of inversion" studied with laser and $\\beta$-NMR spectroscopy

    CERN Document Server

    Kowalska, M

    2006-01-01

    Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable $^{24-26}$Mg, as well as spins and magnetic moments of short-lived $^{29,31}$Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and $\\beta$-NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state $^2\\!$S$_{1/2}$ to one of the two lowest excited states $^2\\!$P$_{1/2 ,\\,3/2}$ using continuous wave laser beams. The isotope-shift measurements with fluor...

  18. 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

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

    African Journals Online (AJOL)

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    3Department of Physics, Arts and Science Faculty, Dumlupinar University, Kütahya, ... 1H, 13C NMR chemical shifts and 1JCH coupling constants of .... then estimated using the corresponding TMS shieldings calculated in advance at the same.

  20. Investigation of zeolites by solid state quadrapole NMR

    International Nuclear Information System (INIS)

    Janssen, R.

    1990-01-01

    The subject of this thesis is the NMR investigation of zeolites. The nature and properties of zeolites are discussed. Some of the basic priniples of NMR techniques on quadrupole nuclei are presented. A special technique, namely a two-dimensional nutation experiment is discussed in detail. The theory of the nutation experiment for quadrupole spin species with spin quantum number 3/2 as well as 5/2 is presented. For both spin spcies the theoretical spectra are compared with experimental results. It is also shown that the nutation expeirment can be performed with several pulse schemes. It is shown how phase-sensitive pure-absorption nutation spectra can be obtained and an NMR-probe is presented that is capable of performing NMR experiments at high (up to 500 degree C) temperatures. The two-dimensional nutation NMR technique has been applied to sodium cations in zeolite NaA. For this purpose a numbre of zeolite samples were prepared that contained different amounts of water. With the aid of nutation NMR the hydration of the zeolite can be studied and conclusions can be drawn about the symmetry of the surrounding of the sodium cations. With the aid of an extension of the nutation NMR experiment: Rotary Echo Nutation NMR, it is shown that in zeolite NaA, in various stages of hydration, the sodium cations or water molecules are mobile. Proof is given by means of high-temperature 23 Na-NMR that dehydrates zeolite NaA undergoes a phase transition at ca. 120 degree C. In a high-temperature NMR investigation of zeolite ZSM-5 it is shown that the sodium ions start to execute motions when the temperature is increased. (author). 198 refs.; 72 figs.; 6 tabs

  1. NMR

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  2. Structural investigations of substituted indolizine derivatives by NMR studies

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  3. NMR study of the paramagnetic state of low-dimensional magnets LiCu{sub 2}O{sub 2} and NaCu{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sadykov, A. F., E-mail: sadykov@imp.uran.ru; Piskunov, Yu. V.; Gerashchenko, A. P.; Ogloblichev, V. V.; Smol’nikov, A. G.; Verkhovskii, S. V.; Arapova, I. Yu.; Volkova, Z. N.; Mikhalev, K. N. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation); Bush, A. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation)

    2017-02-15

    A comprehensive NMR study of the magnetic properties of single crystal LiCu{sub 2}O{sub 2} (LCO) and NaCu{sub 2}O{sub 2} (NCO) is carried out in the paramagnetic region of the compounds for various orientations of single crystals in an external magnetic field. The values of the electric-field gradient (EFG) tensor, as well as the dipole and transferred hyperfine magnetic fields for {sup 63,65}Cu, {sup 7}Li, and {sup 23}Na nuclei are determined. The results are compared with the data obtained in previous NMR studies of the magnetically ordered state of LCO/NCO cuprates.

  4. Solid state NMR of spin-1/2 nuclei

    International Nuclear Information System (INIS)

    Wind, R.A.

    1991-01-01

    The detection of nuclear magnetic resonance by Bloch et al. and Purcell and co-workers in 1946 has led to the development of one of the most powerful spectroscopic techniques known today. The reason is that, besides the applied external magnetic field, a nuclear spin also experiences extra local magnetic fields, which are due to surrounding electron clouds (the chemical shift) and other spins. These local fields differ for nuclei located at chemically different positions in a molecule. The result is that an NMR spectrum often consists of several lines, which can be considered to be a fingerprint of the material under investigation an can assist the clarifying its molecular structure. NMR has been especially successful in liquids and liquid like materials, where fast molecular tumblings average out the anisotropies in the local fields, resulting in well-resolved NMR spectra. This paper reports that initially the development of solid-state NMR was less dramatic. Originally, for reasons of sensitivity, attention was focused mainly on 1 H NMR. The result is that the NMR spectrum usually consists of single, broad, featureless line, which, except for special cases such as more or less isolated spin pairs or methyl groups, does not provide much information

  5. Structural Characterization of Febuxostat/l-Pyroglutamic Acid Cocrystal Using Solid-State 13C-NMR and Investigational Study of Its Water Solubility

    Directory of Open Access Journals (Sweden)

    Ji-Hun An

    2017-12-01

    Full Text Available Febuxostat (FB is a poorly water-soluble drug that belongs to BCS class II. The drug is employed for the treatment of inflammatory disease arthritis urica (gout, and the free base, FB form-A, is most preferred for drug formulation. In order to achieve a goal of improving the water solubility of FB form-A, this study was carried out using the cocrystallization technique called the liquid-assisted grinding method to produce FB cocrystals. Here, five amino acids containing amine (NH, oxygen (O, and hydroxyl (OH functional groups, and possessing difference of pKa less than 3 with FB, were selected as coformers. Then, solvents including methanol, ethanol, isopropyl alcohol, n-hexane, dichloromethane, and acetone were used for the cocrystal screening. As a result, a cocrystal was obtained when acetone and l-pyroglutamic acid (PG of 0.5 eq. were employed as solvent and coformer, respectively. The ratio of 2:1, which is the ratio of FB to PG within FB-PG cocrystal, was predicted by means of solid-state CP/MAS 13C-NMR, solution-state NMR (1H, 13C, and 2D and FT-IR. Moreover, Powder X-ray Diffraction (PXRD, Differential Scanning Calorimetry (DSC, and Thermogravimetric Analysis (TGA were used to investigate the characteristics of FB-PG cocrystal. In addition, comparative solubility tests between FB-PG cocrystal and FB form-A were conducted in deionized water and under simulated gastrointestinal pH (1.2, 4, and 6.8 conditions. The result revealed that FB-PG cocrystal has a solubility of four-fold higher than FB form-A in deionized water and two-fold and five-fold greater than FB form-A at simulated gastrointestinal pH 1.2 and pH 4, respectively. Besides, solubilities of FB-PG cocrystal and FB form-A at pH 6.8 were similar to the results measured in deionized water. Therefore, it is postulated that FB-PG cocrystal has a potential overcoming the limitations related to the low aqueous solubility of FB form-A. Accordingly, FB-PG cocrystal is suggested as an

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

    International Nuclear Information System (INIS)

    Osbakken, M.; Haselgrove, J.

    1987-01-01

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

  7. Solid-State NMR and DFT Studies on the Formation of Well-Defined Silica-Supported Tantallaaziridines: From Synthesis to Catalytic Application

    KAUST Repository

    Hamzaoui, Bilel

    2016-01-27

    Single-site, well-defined, silica-supported tantallaaziridine intermediates [≡Si-O-Ta(η2-NRCH2)(NMe2)2] [R=Me (2), Ph (3)] were prepared from silica-supported tetrakis(dimethylamido)tantalum [≡Si-O-Ta(NMe2)4] (1) and fully characterized by FTIR spectroscopy, elemental analysis, and 1H,13C HETCOR and DQ TQ solid-state (SS) NMR spectroscopy. The formation mechanism, by β-H abstraction, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C-H activation of the dimethylamide ligand is favored for R=Ph. The results from catalytic testing in the hydroaminoalkylation of alkenes were consistent with the N-alkyl aryl amine substrates being more efficient than N-dialkyl amines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 15N and 31P solid-state NMR study of transmembrane domain alignment of M2 protein of influenza A virus in hydrated cylindrical lipid bilayers confined to anodic aluminum oxide nanopores.

    Science.gov (United States)

    Chekmenev, Eduard Y; Hu, Jun; Gor'kov, Peter L; Brey, William W; Cross, Timothy A; Ruuge, Andres; Smirnov, Alex I

    2005-04-01

    This communication reports the first example of a high resolution solid-state 15N 2D PISEMA NMR spectrum of a transmembrane peptide aligned using hydrated cylindrical lipid bilayers formed inside nanoporous anodic aluminum oxide (AAO) substrates. The transmembrane domain SSDPLVVA(A-15N)SIIGILHLILWILDRL of M2 protein from influenza A virus was reconstituted in hydrated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine bilayers that were macroscopically aligned by a conventional micro slide glass support or by the AAO nanoporous substrate. 15N and 31P NMR spectra demonstrate that both the phospholipids and the protein transmembrane domain are uniformly aligned in the nanopores. Importantly, nanoporous AAO substrates may offer several advantages for membrane protein alignment in solid-state NMR studies compared to conventional methods. Specifically, higher thermal conductivity of aluminum oxide is expected to suppress thermal gradients associated with inhomogeneous radio frequency heating. Another important advantage of the nanoporous AAO substrate is its excellent accessibility to the bilayer surface for exposure to solute molecules. Such high accessibility achieved through the substrate nanochannel network could facilitate a wide range of structure-function studies of membrane proteins by solid-state NMR.

  9. Solid-State NMR Spectroscopy for the Physical Chemistry Laboratory

    Science.gov (United States)

    Kinnun, Jacob J.; Leftin, Avigdor; Brown, Michael F.

    2013-01-01

    Solid-state nuclear magnetic resonance (NMR) spectroscopy finds growing application to inorganic and organic materials, biological samples, polymers, proteins, and cellular membranes. However, this technique is often neither included in laboratory curricula nor typically covered in undergraduate courses. On the other hand, spectroscopy and…

  10. Probing Interactions of N-Donor Molecules with Open Metal Sites within Paramagnetic Cr-MIL-101: A Solid-State NMR Spectroscopic and Density Functional Theory Study.

    Science.gov (United States)

    Wittmann, Thomas; Mondal, Arobendo; Tschense, Carsten B L; Wittmann, Johannes J; Klimm, Ottokar; Siegel, Renée; Corzilius, Björn; Weber, Birgit; Kaupp, Martin; Senker, Juergen

    2018-02-14

    Understanding host-guest interactions is one of the key requirements for adjusting properties in metal-organic frameworks (MOFs). In particular, systems with coordinatively unsaturated Lewis acidic metal sites feature highly selective adsorption processes. This is attributed to strong interactions with Lewis basic guest molecules. Here we show that a combination of 13 C MAS NMR spectroscopy with state-of-the-art density functional theory (DFT) calculations allows one to unravel the interactions of water, 2-aminopyridine, 3-aminopyridine, and diethylamine with the open metal sites in Cr-MIL-101. The 13 C MAS NMR spectra, obtained with ultrafast magic-angle spinning, are well resolved, with resonances distributed over 1000 ppm. They present a clear signature for each guest at the open metal sites. Based on competition experiments this leads to the following binding preference: water open metal sites, the NMR data offer additional information about the guest and framework dynamics. We expect that our strategy has the potential for probing the binding situation of adsorbate mixtures at the open metal sites of MOFs in general and thus accesses the microscopic interaction mechanisms for this important material class, which is essential for deriving structure-property relationships.

  11. 17O NMR Studies of the Solvation State of cis/trans Isomers of Amides and Model Protected Peptides

    Science.gov (United States)

    Gerothanassis, Ioannis P.; Vakka, Constantina; Troganis, Anastasios

    1996-06-01

    17O shielding constants have been utilized to investigate solvation differences of the cis/trans isomers ofN-methylformamide (NMF),N-ethylformamide (NEF), andtert-butylformamide (TBF) in a variety of solvents with particular emphasis on aqueous solution. Comparisons are also made with protected peptides of the formulas CH3CO-YOH, CH3CO-Y-NHR (Y = Pro, Sar), and CH3CO-Y-Z-NHR (Y = Pro; Z =D-Ala) selectively enriched in17O at the acetyl oxygen atom. Hydration at the amide oxygen induces large and specific modifications of the17O shielding constants, which are practically the same for the cis and trans isomers of NMF, NEF, and the protected peptides. Fortert-butylformamide, the strong deshielding of the trans isomer compared to that of the cis isomer may be attributed to an out-of-plane (torsion-angle) deformation of the amide bond and/or a significant reduction of solvation of the trans isomer due to steric inhibition of the bulkytert-butyl group. Good linear correlation between δ(17O) of amides and δ(17O) of acetone was found for different solvents which have varying dielectric constants and solvation abilities. Sum-over-states calculations, within the solvaton model, underestimate effects of the dielectric constant of the medium on17O shielding, while finite-perturbation-theory calculations give good agreement with the experiment.

  12. 17O NMR Studies of the Solvation State of cissolidustrans Isomers of Amides and Model Protected Peptides

    Science.gov (United States)

    Gerothanassis; Vakka; Troganis

    1996-06-01

    17O shielding constants have been utilized to investigate solvation differences of the cissolidustrans isomers of N-methylformamide (NMF), N-ethylformamide (NEF), and tert-butylformamide (TBF) in a variety of solvents with particular emphasis on aqueous solution. Comparisons are also made with protected peptides of the formulas CH3CO-YOH, CH3CO-Y-NHR (Y = Pro, Sar), and CH3CO-Y-Z-NHR (Y = Pro; Z = D-Ala) selectively enriched in 17O at the acetyl oxygen atom. Hydration at the amide oxygen induces large and specific modifications of the 17O shielding constants, which are practically the same for the cis and trans isomers of NMF, NEF, and the protected peptides. For tert-butylformamide, the strong deshielding of the trans isomer compared to that of the cis isomer may be attributed to an out-of-plane (torsion-angle) deformation of the amide bond andsolidusor a significant reduction of solvation of the trans isomer due to steric inhibition of the bulky tert-butyl group. Good linear correlation between delta(17O) of amides and delta(17O) of acetone was found for different solvents which have varying dielectric constants and solvation abilities. Sum-over-states calculations, within the solvaton model, underestimate effects of the dielectric constant of the medium on 17O shielding, while finite-perturbation-theory calculations give good agreement with the experiment.

  13. NMR studies of spin dynamics in cuprates

    International Nuclear Information System (INIS)

    Takigawa, M.; Mitzi, D.B.

    1994-01-01

    The authors report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi 2.1 Sr 1.94 Ca 0.88 Cu 2.07 O 8+σ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa 2 Cu 3 O 6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector

  14. NMR studies of spin dynamics in cuprates

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-04-01

    We report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi2.1Sr1.94Ca0.88Cu2.07O8+δ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa2Cu3O6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector.

  15. Low electron density of states at the boron site of TMB{sub 2} (TM = Ti, Zr, Hf, and Nb): a {sup 11}B NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, S.; Zogal, O.J.; Peshev, P

    2004-11-30

    The local density of states at the boron site in TMB{sub 2} (TM=Ti, Zr, Hf, and Nb) has been examined using the solid-state {sup 11}B NMR technique. The magic angle spinning (MAS) NMR spectra at room temperature and the spin-lattice relaxation rates have been measured as functions of temperature (30-293 K). The resonance line shifts are small and become more negative in the direction from 3d- to 5d-elements. The relaxation rates follow a linear law characteristic of hyperfine magnetic interaction with conduction electrons. With borides of IV group metals the data can be understood in terms of a very low s-electron density of states and absence of a p-character of the conduction electron wave function at the Fermi level while in the case of NbB{sub 2} a small partial p-electron density of states is assumed. Then, the results are in good agreement with the earlier theoretical prediction.

  16. Comparative study on occurrence characteristics of matrix water in static and gas double-dynamic solid-state fermentations using low-field NMR and MRI.

    Science.gov (United States)

    He, Qin; Chen, Hong-zhang

    2015-12-01

    The water in a solid substrate is generally divided into three forms: hygroscopic, capillary, and free. However, there are few methods available for detecting the contents of different states of water in substrates. In this paper, low-field NMR and MRI were used to analyze the water occurrence characteristics of steam-exploded corn straw in solid-state fermentation (SSF). A significant linear relationship was found between the total NMR peak areas and the total water contents with a correlation coefficient of 0.993. It was further proved to be successful in comparing the contents and distributions of different states of water in static SSF and gas double-dynamic SSF (GDD-SSF). The results showed that among the three states of water, capillary water was the main form of water present and lost in substrates during fermentation. Total water and capillary water contents did not significantly differ as a result of different sample treatments, but hygroscopic water and free water contents in static SSF were respectively 0.38 and 2.98 times that in GDD-SSF with a packing height of 3 cm after fermentation. A relatively uniform water distribution and deep-depth region for microbial growth were found in GDD-SSF, suggesting that GDD-SSF was more suitable for industrialization. This technology has great potential for achieving efficient on-line water supply through water loss detection in SSF.

  17. Lipid Dynamics Studied by Calculation of 31P Solid-State NMR Spectra Using Ensembles from Molecular Dynamics Simulations

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh; Vestergaard, Mikkel; Thøgersen, Lea

    2014-01-01

    , for example, order parameters. Therefore, valuable insight into the dynamics of biomolecules may be achieved by the present method. We have applied this method to study the dynamics of lipid bilayers containing the antimicrobial peptide alamethicin, and we show that the calculated 31P spectra obtained...

  18. Liquid state sup1H and sup13C-NMR studies on polymerisation reaction of 2,2'-difurfuryloxy-2- silapropane

    International Nuclear Information System (INIS)

    Rusli bin Omar

    1994-01-01

    The purpose of this study was to prepare the copolymer of 2,2'-difurfuryloxy-2-silapropane (DFS) and 1,1'-(methylenedi-4, 1-phenylene) bismaleimide (BM). DFS was prepared at 0 degC through the reaction of 2 moles of furfuryl alcohol (FA) with 1 mole of dichlorodimethylsilane (DCMS) in the presence of pyridine and chloroform as a solvent. The formation of this compound was characterized by the sup1H and sup13C-NMR spectroscopy and mass spectrometry. DFS has the ability to undergo the Diels-Alder reaction. The furan end groups of DFS could react with dienophile groups of other materials. The adduct of DFS-BM was prepared by the reaction of DFS with BM at room temperature (18degC) in chloroform (CDClsub3). Characterization of the adduct was carried out through a study of the sup1H and sup13C-NMR spectra of the adduct

  19. Magnetic structure and spin dynamics of the ground state of the molecular cluster Mn12O12 acetate studied by 55Mn NMR

    International Nuclear Information System (INIS)

    Furukawa, Y.; Watanabe, K.; Kumagai, K.; Borsa, F.; Gatteschi, D.

    2001-01-01

    55 Mn nuclear magnetic resonance (NMR) measurements have been carried out in an oriented powder sample of Mn12 acetate at low temperature (1.4--3 K) in order to investigate locally the static and dynamic magnetic properties of the molecule in its high-spin S=10 ground state. We report the observation of three 55 MnNMR lines under zero external magnetic field. From the resonance frequency and the width of the lines we derive the internal hyperfine field and the quadrupole coupling constant at each of the three nonequivalent Mn ion sites. From the field dependence of the spectrum we obtain a direct confirmation of the standard picture, in which spin moments of Mn 4+ ions (S=3/2) of the inner tetrahedron are polarized antiparallel to that of Mn 3+ ions (S=2) of the outer ring with no measurable canting from the easy axis up to an applied field of 6 T. It is found that the splitting of the 55 Mn-NMR lines when a magnetic field is applied at low temperature allows one to monitor the off-equilibrium population of the molecules in the different low lying magnetic states. The measured nuclear spin-lattice relaxation time T 1 strongly depends on temperature and magnetic field. The behavior could be fitted well by considering the local-field fluctuations at the nuclear 55 Mn site due to the thermal reorientation of the total S=10 spin of the molecule. From the fit of the data one can derive the product of the spin-phonon coupling constant times the mean-square value of the fluctuating hyperfine field. The two constants could be estimated separately by making some assumptions. The comparison of the mean-square fluctuation from relaxation with the static hyperfine field from the spectrum suggests that nonuniform terms (q≠0) are important in describing the spin dynamics of the local Mn moments in the ground state

  20. Efficient cellular solid-state NMR of membrane proteins by targeted protein labeling

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Lindsay A. [University of Oxford, Oxford Particle Imaging Centre, The Wellcome Trust Centre for Human Genetics, Division of Structural Biology, Nuffield Department of Medicine (United Kingdom); Daniëls, Mark; Cruijsen, Elwin A. W. van der; Folkers, Gert E.; Baldus, Marc, E-mail: m.baldus@uu.nl [Utrecht University, NMR Spectroscopy, Department of Chemistry, Faculty of Science, Bijvoet Center for Biomolecular Research (Netherlands)

    2015-06-15

    Solid-state NMR spectroscopy (ssNMR) has made significant progress towards the study of membrane proteins in their native cellular membranes. However, reduced spectroscopic sensitivity and high background signal levels can complicate these experiments. Here, we describe a method for ssNMR to specifically label a single protein by repressing endogenous protein expression with rifampicin. Our results demonstrate that treatment of E. coli with rifampicin during induction of recombinant membrane protein expression reduces background signals for different expression levels and improves sensitivity in cellular membrane samples. Further, the method reduces the amount of time and resources needed to produce membrane protein samples, enabling new strategies for studying challenging membrane proteins by ssNMR.

  1. Efficient cellular solid-state NMR of membrane proteins by targeted protein labeling

    International Nuclear Information System (INIS)

    Baker, Lindsay A.; Daniëls, Mark; Cruijsen, Elwin A. W. van der; Folkers, Gert E.; Baldus, Marc

    2015-01-01

    Solid-state NMR spectroscopy (ssNMR) has made significant progress towards the study of membrane proteins in their native cellular membranes. However, reduced spectroscopic sensitivity and high background signal levels can complicate these experiments. Here, we describe a method for ssNMR to specifically label a single protein by repressing endogenous protein expression with rifampicin. Our results demonstrate that treatment of E. coli with rifampicin during induction of recombinant membrane protein expression reduces background signals for different expression levels and improves sensitivity in cellular membrane samples. Further, the method reduces the amount of time and resources needed to produce membrane protein samples, enabling new strategies for studying challenging membrane proteins by ssNMR

  2. DNA oligonucleotide conformations: high resolution NMR studies

    International Nuclear Information System (INIS)

    Mellema, J.-R.

    1984-01-01

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

  3. Characterization of Two Distinct Amorphous Forms of Valsartan by Solid-State NMR.

    Science.gov (United States)

    Skotnicki, Marcin; Apperley, David C; Aguilar, Juan A; Milanowski, Bartłomiej; Pyda, Marek; Hodgkinson, Paul

    2016-01-04

    Valsartan (VAL) is an antihypertensive drug marketed in an amorphous form. Amorphous materials can have different physicochemical properties depending on preparation method, thermal history, etc., but the nature of such materials is difficult to study by diffraction techniques. This study characterizes two different amorphous forms of valsartan (AR and AM) using solid-state NMR (SSNMR) as a primary investigation tool, supported by solution-state NMR, FT-IR, TMDSC, and dissolution tests. The two forms are found to be clearly distinct, with a significantly higher level of structural arrangement in the AR form, as observed in (13)C, (15)N, and (1)H SSNMR. (13)C and (15)N NMR indicates that the fully amorphous material (AM) contains an approximately equal ratio of cis-trans conformers about the amide bond, whereas the AR form exists mainly as one conformer, with minor conformational "defects". (1)H ultrafast MAS NMR shows significant differences in the hydrogen bonding involving the tetrazole and acid hydrogens between the two materials, while (15)N NMR shows that both forms exist as a 1,2,3,4-tetrazole tautomer. NMR relaxation times show subtle differences in local and bulk molecular mobility, which can be connected with the glass transition, the stability of the glassy material, and its response to aging. Counterintuitively the fully amorphous material is found to have a significantly lower dissolution rate than the apparently more ordered AR material.

  4. Modification and intercalation of layered zirconium phosphates: a solid-state NMR monitoring.

    Science.gov (United States)

    Bakhmutov, Vladimir I; Kan, Yuwei; Sheikh, Javeed Ahmad; González-Villegas, Julissa; Colón, Jorge L; Clearfield, Abraham

    2017-07-01

    Several layered zirconium phosphates treated with Zr(IV) ions, modified by monomethoxy-polyethyleneglycol-monophosphate and intercalated with doxorubicin hydrochloride have been studied by solid-state MAS NMR techniques. The organic components of the phosphates have been characterized by the 13 C{ 1 H} CP MAS NMR spectra compared with those of initial compounds. The multinuclear NMR monitoring has provided to establish structure and covalent attachment of organic/inorganic moieties to the surface and interlayer spaces of the phosphates. The MAS NMR experiments including kinetics of proton-phosphorus cross polarization have resulted in an unusual structure of zirconium phosphate 6 combining decoration of the phosphate surface by polymer units and their partial intercalation into the interlayer space. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Rhodopsin-lipid interactions studied by NMR.

    Science.gov (United States)

    Soubias, Olivier; Gawrisch, Klaus

    2013-01-01

    The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200-nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60μm yields on the order of 500cm(2) of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated, and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By (2)H NMR order parameter measurements, it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by (1)H saturation-transfer NMR under conditions of magic angle spinning, we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Peakr: simulating solid-state NMR spectra of proteins

    International Nuclear Information System (INIS)

    Schneider, Robert; Odronitz, Florian; Hammesfahr, Bjorn; Hellkamp, Marcel; Kollmar, Martin

    2013-01-01

    When analyzing solid-state nuclear magnetic resonance (NMR) spectra of proteins, assignment of resonances to nuclei and derivation of restraints for 3D structure calculations are challenging and time-consuming processes. Simulated spectra that have been calculated based on, for example, chemical shift predictions and structural models can be of considerable help. Existing solutions are typically limited in the type of experiment they can consider and difficult to adapt to different settings. Here, we present Peakr, a software to simulate solid-state NMR spectra of proteins. It can generate simulated spectra based on numerous common types of internuclear correlations relevant for assignment and structure elucidation, can compare simulated and experimental spectra and produces lists and visualizations useful for analyzing measured spectra. Compared with other solutions, it is fast, versatile and user friendly. (authors)

  7. 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...

  8. Solid-state NMR of the Yersinia pestis outer membrane protein Ail in lipid bilayer nanodiscs sedimented by ultracentrifugation

    International Nuclear Information System (INIS)

    Ding, Yi; Fujimoto, L. Miya; Yao, Yong; Marassi, Francesca M.

    2015-01-01

    Solid-state NMR studies of sedimented soluble proteins has been developed recently as an attractive approach for overcoming the size limitations of solution NMR spectroscopy while bypassing the need for sample crystallization or precipitation (Bertini et al. Proc Natl Acad Sci USA 108(26):10396–10399, 2011). Inspired by the potential benefits of this method, we have investigated the ability to sediment lipid bilayer nanodiscs reconstituted with a membrane protein. In this study, we show that nanodiscs containing the outer membrane protein Ail from Yersinia pestis can be sedimented for solid-state NMR structural studies, without the need for precipitation or lyophilization. Optimized preparations of Ail in phospholipid nanodiscs support both the structure and the fibronectin binding activity of the protein. The same sample can be used for solution NMR, solid-state NMR and activity assays, facilitating structure–activity correlation experiments across a wide range of timescales

  9. Solid-state NMR of the Yersinia pestis outer membrane protein Ail in lipid bilayer nanodiscs sedimented by ultracentrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yi; Fujimoto, L. Miya; Yao, Yong; Marassi, Francesca M., E-mail: fmarassi@sbmri.org [Sanford-Burnham Medical Research Institute (United States)

    2015-04-15

    Solid-state NMR studies of sedimented soluble proteins has been developed recently as an attractive approach for overcoming the size limitations of solution NMR spectroscopy while bypassing the need for sample crystallization or precipitation (Bertini et al. Proc Natl Acad Sci USA 108(26):10396–10399, 2011). Inspired by the potential benefits of this method, we have investigated the ability to sediment lipid bilayer nanodiscs reconstituted with a membrane protein. In this study, we show that nanodiscs containing the outer membrane protein Ail from Yersinia pestis can be sedimented for solid-state NMR structural studies, without the need for precipitation or lyophilization. Optimized preparations of Ail in phospholipid nanodiscs support both the structure and the fibronectin binding activity of the protein. The same sample can be used for solution NMR, solid-state NMR and activity assays, facilitating structure–activity correlation experiments across a wide range of timescales.

  10. Distinct solvent- and temperature-dependent packing arrangements of anti-parallel β-sheet polyalanines studied with solid-state 13C NMR and MD simulation.

    Science.gov (United States)

    Kametani, Shunsuke; Tasei, Yugo; Nishimura, Akio; Asakura, Tetsuo

    2017-08-09

    Polyalanine (polyA) sequences are well known as the simplest sequence that naturally forms anti-parallel β-sheets and constitute a key element in the structure of spider and wild silkworm silk fibers. We have carried out a systematic analysis of the packing of anti-parallel β-sheets for (Ala) n , n = 5, 6, 7 and 12, using primarily 13 C solid-state NMR and MD simulation. HFIP and TFA are frequently used as the dope solvents for recombinant silks, and polyA was solidified from both HFIP and TFA solutions by drying. An analysis of Ala Cβ peaks in the 13 C CP/MAS NMR spectra indicated that polyA from HFIP was mainly rectangular but polyA from TFA was mainly staggered. The transition from the rectangular to the staggered arrangement in (Ala) 6 was observed for the first time from the change in the Ala Cβ peak through heat treatment at 200 °C for 4 h. The removal of the bound water was confirmed by thermal analysis. This transition could be reproduced by MD simulation of (Ala) 6 molecules at 200 °C after removal of the bound water molecules. In this way, the origin of the stability of the different packing arrangements of polyA was clarified.

  11. Solid-state NMR on complex biomolecules: novel methods and applications

    NARCIS (Netherlands)

    Nand, D.

    2011-01-01

    Solid-state NMR (ssNMR) represents a versatile technique in providing atomic-resolution information without the need for crystals or fast molecular motion required for X-ray crystallography and solution-state NMR, respectively. Recent past has witnessed the ability of this technique in providing

  12. Single crystal NMR studies of high temperature superconductors

    International Nuclear Information System (INIS)

    Pennington, C.H.; Durand, D.J.; Zax, D.B.; Slichter, C.P.; Rice, J.P.; Bukowski, E.D.; Ginsberg, D.M.

    1989-01-01

    The authors report Cu NMR studies in the normal state of a single crystal of the T/sub c/ = 90 K superconductor YBa 2 Cu 3 O/sub 7/minus/δ/. The authors have measured the magnetic shift tensor, the electric field gradient tensor, the nuclear spin-lattice relaxation rate tensor, and the time dependence and functional form of the transverse decay. From these data they obtain information about the charge state and magnetic state of the Cu atoms, and the existence and size of the electronic exchange coupling between spins of adjacent Cu atoms. 18 refs., 3 figs., 2 tabs

  13. 13C solid state NMR investigation of natural resins components

    International Nuclear Information System (INIS)

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

    2001-01-01

    The objective of this work is to establish and analytical methodology as a routine using solid state nuclear magnetic resonance (NMR) techniques to investigate the mainly chemical components presented in natural resins in bulk. And also to evaluate the molecular behaviour of these resins. The routine solid state techniques allow us to assign the main compounds presented in the resins. Therefore, applying specialised techniques, like variable contact time, delayed contact time, dephasing time and proton spin lattice relaxation time in the rotating frame (T 1 H ρ), more information about chemical structure and molecular dynamic is available

  14. High-resolution solution-state NMR of unfractionated plant cell walls

    Science.gov (United States)

    John Ralph; Fachuang Lu; Hoon Kim; Dino Ress; Daniel J. Yelle; Kenneth E. Hammel; Sally A. Ralph; Bernadette Nanayakkara; Armin Wagner; Takuya Akiyama; Paul F. Schatz; Shawn D. Mansfield; Noritsugu Terashima; Wout Boerjan; Bjorn Sundberg; Mattias Hedenstrom

    2009-01-01

    Detailed structural studies on the plant cell wall have traditionally been difficult. NMR is one of the preeminent structural tools, but obtaining high-resolution solution-state spectra has typically required fractionation and isolation of components of interest. With recent methods for dissolution of, admittedly, finely divided plant cell wall material, the wall can...

  15. NMR studies of transmembrane electron transport in human erythrocytes

    International Nuclear Information System (INIS)

    Kennett, E.C.; Bubb, W.A.; Kuchel, P.W.

    2002-01-01

    Full text: Electron transport systems exist in the plasma membranes of all cells. These systems appear to play a role in cell growth and proliferation, intracellular signalling, hormone responses, apoptotic events, cell defence and perhaps most importantly they enable the cell to respond to changes in the redox state of both the intra- and extracellular environments. Previously, 13 C NMR has been used to study transmembrane electron transport in human erythrocytes, specifically the reduction of extracellular 13 C-ferricyanide. NMR is a particularly useful tool for studying such systems as changes in the metabolic state of the cell can be observed concomitantly with extracellular reductase activity. We investigated the oxidation of extracellular NADH by human erythrocytes using 1 H and 31 P NMR spectroscopy. Recent results for glucose-starved human erythrocytes indicate that, under these conditions, extracellular NADH can be oxidised at the plasma membrane with the electron transfer across the membrane resulting in reduction of intracellular NAD + . The activity is inhibited by known trans-plasma membrane electron transport inhibitors (capsaicin and atebrin) and is unaffected by inhibition of the erythrocyte Band 3 anion transporter. These results suggest that electron import from extracellular NADH allows the cell to re-establish a reducing environment after the normal redox balance is disturbed

  16. Solid-state 29Si NMR and FTIR analyses of lignin-silica coprecipitates

    DEFF Research Database (Denmark)

    Cabrera Orozco, Yohanna; Cabrera, Andrés; Larsen, Flemming Hofmann

    2016-01-01

    When agricultural residues are processed to ethanol, lignin and silica are some of the main byproducts. Separation of these two products is difficult and the chemical interactions between lignin and silica are not well described. In the present study, the effect of lignin-silica complexing has been...... investigated by characterizing lignin and silica coprecipitates by FTIR and solid state NMR. Silica particles were coprecipitated with three different lignins, three lignin model compounds, and two silanes representing silica-in-lignin model compounds. Comparison of 29Si SP/MAS NMR spectra revealed differences...

  17. Yeast-expressed human membrane protein aquaporin-1 yields excellent resolution of solid-state MAS NMR spectra

    International Nuclear Information System (INIS)

    Emami, Sanaz; Fan Ying; Munro, Rachel; Ladizhansky, Vladimir; Brown, Leonid S.

    2013-01-01

    One of the biggest challenges in solid-state NMR studies of membrane proteins is to obtain a homogeneous natively folded sample giving high spectral resolution sufficient for structural studies. Eukaryotic membrane proteins are especially difficult and expensive targets in this respect. Methylotrophic yeast Pichia pastoris is a reliable producer of eukaryotic membrane proteins for crystallography and a promising economical source of isotopically labeled proteins for NMR. We show that eukaryotic membrane protein human aquaporin 1 can be doubly ( 13 C/ 15 N) isotopically labeled in this system and functionally reconstituted into phospholipids, giving excellent resolution of solid-state magic angle spinning NMR spectra.

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

    International Nuclear Information System (INIS)

    Wright, P.E.

    1994-01-01

    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 13 C, 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 13 C and 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

  19. 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.

  20. Proton NMR studies of functionalized nanoparticles in aqueous environments

    Science.gov (United States)

    Tataurova, Yulia Nikolaevna

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

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

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa

    2016-08-11

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

  2. Effects of cooking on the cell walls (dietary fiber) of 'Scarlet Warren' winter squash ( Cucurbita maxima ) studied by polysaccharide linkage analysis and solid-state (13)C NMR.

    Science.gov (United States)

    Ratnayake, R M Sunil; Sims, Ian M; Newman, Roger H; Melton, Laurence D

    2011-07-13

    Cell wall polysaccharides of 'Scarlet Warren' winter squash ( Cucurbita maxima ) were investigated before and after thermal processing. Linkage analysis of polysaccharides was done by gas chromatography coupled to mass spectrometry (GC-MS). The linkage analysis showed the cell wall polysaccharide compositions of raw and cooked squash were similar. The total pectic polysaccharides (galacturonan, rhamnogalacturonan, arabinan, and arabinogalactan) contents of the cell walls of both raw and cooked squash were 39 mol %. The amounts of pectic polysaccharides and xyloglucan in the cell walls of squash showed little alteration on heating. The cellulose content of the raw and cooked cell walls was relatively high at 47 mol %, whereas the xyloglucan content was low at 4 mol %. Solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy techniques were used to examine the molecular motion of the polysaccharides in the cell walls. The mobility of highly flexible galactan depends on the water content of the sample, but no difference was seen between raw and cooked samples. Likewise, the mobility of semimobile pectic polysaccharides was apparently unaltered by cooking. No change was detected in the rigid cellulose microfibrils on cooking.

  3. In situ solid-state NMR and XRD studies of the ADOR process and the unusual structure of zeolite IPC-6

    Science.gov (United States)

    Morris, Samuel A.; Bignami, Giulia P. M.; Tian, Yuyang; Navarro, Marta; Firth, Daniel S.; Čejka, Jiří; Wheatley, Paul S.; Dawson, Daniel M.; Slawinski, Wojciech A.; Wragg, David S.; Morris, Russell E.; Ashbrook, Sharon E.

    2017-10-01

    The assembly-disassembly-organization-reassembly (ADOR) mechanism is a recent method for preparing inorganic framework materials and, in particular, zeolites. This flexible approach has enabled the synthesis of isoreticular families of zeolites with unprecedented continuous control over porosity, and the design and preparation of materials that would have been difficult—or even impossible—to obtain using traditional hydrothermal techniques. Applying the ADOR process to a parent zeolite with the UTL framework topology, for example, has led to six previously unknown zeolites (named IPC-n, where n = 2, 4, 6, 7, 9 and 10). To realize the full potential of the ADOR method, however, a further understanding of the complex mechanism at play is needed. Here, we probe the disassembly, organization and reassembly steps of the ADOR process through a combination of in situ solid-state NMR spectroscopy and powder X-ray diffraction experiments. We further use the insight gained to explain the formation of the unusual structure of zeolite IPC-6.

  4. Protein structural studies by paramagnetic solid-state NMR spectroscopy aided by a compact cyclen-type Cu(II) binding tag

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Ishita; Gao, Min; Arachchige, Rajith J.; Nadaud, Philippe S. [The Ohio State University, Department of Chemistry and Biochemistry (United States); Cunningham, Timothy F.; Saxena, Sunil [University of Pittsburgh, Department of Chemistry (United States); Schwieters, Charles D. [National Institutes of Health, Center for Information Technology (United States); Jaroniec, Christopher P., E-mail: jaroniec@chemistry.ohio-state.edu [The Ohio State University, Department of Chemistry and Biochemistry (United States)

    2015-01-15

    Paramagnetic relaxation enhancements (PREs) are a rich source of structural information in protein solid-state NMR spectroscopy. Here we demonstrate that PRE measurements in natively diamagnetic proteins are facilitated by a thiol-reactive compact, cyclen-based, high-affinity Cu{sup 2+} binding tag, 1-[2-(pyridin-2-yldisulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (TETAC), that overcomes the key shortcomings associated with the use of larger, more flexible metal-binding tags. Using the TETAC–Cu{sup 2+} K28C mutant of B1 immunoglobulin-binding domain of protein G as a model, we find that amino acid residues located within ∼10 Å of the Cu{sup 2+} center experience considerable transverse PREs leading to severely attenuated resonances in 2D {sup 15}N–{sup 13}C correlation spectra. For more distant residues, electron–nucleus distances are accessible via quantitative measurements of longitudinal PREs, and we demonstrate such measurements for {sup 15}N–Cu{sup 2+} distances up to ∼20 Å.

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

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa; Sofack-Kreutzer, Julien; Minenkov, Yury; Abou-Hamad, Edy; Hamzaoui, Bilel; Werghi, Baraa; Anjum, Dalaver H.; Cavallo, Luigi; Huang, Kuo-Wei; Basset, Jean-Marie

    2016-01-01

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

  6. Theoretical predictions of the two-dimensional solid-state NMR spectra: a case study of the 13C-1H correlations in metergoline

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Brus, Jiří

    2013-01-01

    Roč. 586, 24 October (2013), s. 56-60 ISSN 0009-2614 Institutional support: RVO:61389013 Keywords : NMR * shielding * metergoline Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.991, year: 2013

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

    Science.gov (United States)

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

    2013-09-17

    Electrochemical cells, in the form of batteries (or supercapacitors) and fuel cells, are efficient devices for energy storage and conversion. These devices show considerable promise for use in portable and static devices to power electronics and various modes of transport and to produce and store electricity both locally and on the grid. For example, high power and energy density lithium-ion batteries are being developed for use in hybrid electric vehicles where they improve the efficiency of fuel use and help to reduce greenhouse gas emissions. To gain insight into the chemical reactions involving the multiple components (electrodes, electrolytes, interfaces) in the electrochemical cells and to determine how cells operate and how they fail, researchers ideally should employ techniques that allow real-time characterization of the behavior of the cells under operating conditions. This Account reviews the recent use of in situ solid-state NMR spectroscopy, a technique that probes local structure and dynamics, to study these devices. In situ NMR studies of lithium-ion batteries are performed on the entire battery, by using a coin cell design, a flat sealed plastic bag, or a cylindrical cell. The battery is placed inside the NMR coil, leads are connected to a potentiostat, and the NMR spectra are recorded as a function of state of charge. (7)Li is used for many of these experiments because of its high sensitivity, straightforward spectral interpretation, and relevance to these devices. For example, (7)Li spectroscopy was used to detect intermediates formed during electrochemical cycling such as LixC and LiySiz species in batteries with carbon and silicon anodes, respectively. It was also used to observe and quantify the formation and growth of metallic lithium microstructures, which can cause short circuits and battery failure. This approach can be utilized to identify conditions that promote dendrite formation and whether different electrolytes and additives can help

  8. 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...

  9. NMR study of LaPb2

    International Nuclear Information System (INIS)

    Ueda, K.; Kohara, T.; Yamada, Y.

    1995-01-01

    La and Pb NMR signals were observed in LaPb 2 with a superconducting transition temperature of about 7 K. The width of the Pb NMR spectrum with an asymmetric line shape was rather narrower than those of Er-, Gd- and Ho-Pb 2 . The spin-lattice relaxation time of Pb nuclei was twice longer than that of Pb metal. La NMR spectrum had satellites due to the electric quadrupole interaction. These results show that each local environment at La or Pb site in LaPb 2 compound is uniquely determined, compared with those in randomly substituted alloys. ((orig.))

  10. Solid state NMR, basic theory and recent progress for quadrupole nuclei with half-integer spin

    International Nuclear Information System (INIS)

    Dieter, F.

    1998-01-01

    This review describes the basic theory and some recently developed techniques for the study of quadrupole nuclei with half integer spins in powder materials. The latter is connected to the introduction of the double rotation (DOR) by A. Samoson et al. (1) and to the introduction of the multiple quantum magic-angle spinning (MQ MAS) technique by L. Frydman et. al. (2). For integer spins, especially the solid-state deuterium magnetic resonance, we refer to the review of G.L. Hoatson and R.L. Vold: '' 2 H-NMR Spectroscopy of Solids and Liquid Crystals'' (3). For single crystals we refer to O. Kanert and M. Mehring: ''Static quadrupole effects in disordered cubic solids''(4) and we would like also to mention the ''classic'' review of M.H. Cohen and F. Reif: ''Quadrupole effects in NMR studies of solids'' (5). Some more recent reviews in the field under study are D. Freude and J. Haase ''Quadrupole effects in solid-state NMR'' (6). Ch. Jager: ''Satellite Transition Spectroscopy of Quadrupolar Nuclei'' (7) and B.F. Chmelka and J.W. Zwanziger: ''Solid State NMR Line Narrowing Methods for Quadrupolar Nuclei - Double Rotation and Dynamic-Angle Spinning'' (8). A survey of nuclear quadrupole frequency data published before the end of 1982 is given by H. Chihara and N. Nakamura in Landolt-Bornstein, Vol. 20 (9). Values of the chemical shift of quadrupole nuclei in solids can be found in books such as ''Multinuclear NMR'' edited by J. Mason (10). In section 9 of ref (6) some electric field gradient and chemical shift data published from 1983 to 1992 for the most studied quadrupole nuclei sup 27 Al, sup 23 Na, and sup 17 O are given

  11. Recent advances in solid state NMR and its application to ceramics

    International Nuclear Information System (INIS)

    Maekawa, Hideki

    2006-01-01

    The basic principles of solid state NMR are explained. Four application examples contained amorphous glass, determination of defects of oxide crystal, nano particle and ionic materials. The structure of inorganic glass is measured by 29 Si, 11 B, 31 P and 23 Na NMR and Magic Angle Spinning NMR (MAS-NMR), chemical species near hydrogen by Cross-Polarization Magic Angle Spinning (CP/MAS) method, and hydrogen by Combined Rotation And Multiple Pulse Spectroscopy (CRAMPS) and MAS-NMR. Hydrous and anhydrous silicate glass with condensed 17 O was measured by 17 O Multi Quantum Magic Angle Spinning (MQ/MAS). 27 Al in slags was analyzed by 27 Al 5Q-MAS. 89 Y NMR spectrum of YSZ (Yttria Stabilization Zirconia, Y 2 O 3 -ZrO 2 ) was explained. The ion transfer phenomena in the electrolyte are observed directly by the solid state NMR. (S.Y.)

  12. 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.

  13. 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.

  14. Studies of Superfluid 3He Confined to a Regular Submicron Slab Geometry, Using SQUID NMR

    International Nuclear Information System (INIS)

    Casey, Andrew; Corcoles, Antonio; Lusher, Chris; Cowan, Brian; Saunders, John

    2006-01-01

    The effect on the superfluid ground state of confining p-wave superfluid 3He in regular geometries of characteristic size comparable to the diameter of the Cooper pair remains relatively unexplored, in part because of the demands placed by experiments on the sensitivity of the measuring technique. In this paper we report preliminary experiments aimed at the study of 3He confined to a slab geometry. The NMR response of a series of superfluid samples has been investigated using a SQUID NMR amplifier. The sensitivity of this NMR spectrometer enables samples of order 1017 spins, with low filling factor, to be studied with good resolution

  15. Multinuclear solid-state high-resolution and C-13 -{Al-27} double-resonance magic-angle spinning NMR studies on aluminum alkoxides

    NARCIS (Netherlands)

    Abraham, A.; Prins, R.; Bokhoven, J.A. van; Eck, E.R.H. van; Kentgens, A.P.M.

    2006-01-01

    A combination of Al-27 magic-angle spinning (MAS)/multiple quantum (MQ)-MAS, C-13-H-1 CPMAS, and C-13-{Al-27} transfer of population in double-resonance (TRAPDOR) nuclear magnetic resonance (NMR) were used for the structural elucidation of the aluminum alkoxides aluminum ethoxide, aluminum

  16. In situ solid-state NMR and XRD studies of the ADOR process and the unusual structure of zeolite IPC-6

    Czech Academy of Sciences Publication Activity Database

    Morris, S. A.; Bignami, G. P. M.; Tian, Y.; Navarro, M.; Firth, D. S.; Čejka, Jiří; Wheatley, P. S.; Dawson, D. M.; Slawinski, W. A.; Wragg, D. S.; Morris, R. E.; Ashbrook, S. E.

    2017-01-01

    Roč. 9, č. 10 (2017), s. 1012-1018 ISSN 1755-4330 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : NMR * XRD * ADOR process Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 25.870, year: 2016

  17. Solid-state NMR, electrophysiology and molecular dynamics characterization of human VDAC2

    International Nuclear Information System (INIS)

    Gattin, Zrinka; Schneider, Robert; Laukat, Yvonne; Giller, Karin; Maier, Elke; Zweckstetter, Markus; Griesinger, Christian; Benz, Roland; Becker, Stefan; Lange, Adam

    2015-01-01

    The voltage-dependent anion channel (VDAC) is the most abundant protein of the outer mitochondrial membrane and constitutes the major pathway for the transport of ADP, ATP, and other metabolites. In this multidisciplinary study we combined solid-state NMR, electrophysiology, and molecular dynamics simulations, to study the structure of the human VDAC isoform 2 in a lipid bilayer environment. We find that the structure of hVDAC2 is similar to the structure of hVDAC1, in line with recent investigations on zfVDAC2. However, hVDAC2 appears to exhibit an increased conformational heterogeneity compared to hVDAC1 which is reflected in broader solid-state NMR spectra and less defined electrophysiological profiles

  18. Solid-state NMR, electrophysiology and molecular dynamics characterization of human VDAC2

    Energy Technology Data Exchange (ETDEWEB)

    Gattin, Zrinka; Schneider, Robert; Laukat, Yvonne; Giller, Karin [Max Planck Institute for Biophysical Chemistry (Germany); Maier, Elke [Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Lehrstuhl für Biotechnologie (Germany); Zweckstetter, Markus; Griesinger, Christian [Max Planck Institute for Biophysical Chemistry (Germany); Benz, Roland [Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Lehrstuhl für Biotechnologie (Germany); Becker, Stefan; Lange, Adam, E-mail: alange@fmp-berlin.de [Max Planck Institute for Biophysical Chemistry (Germany)

    2015-04-15

    The voltage-dependent anion channel (VDAC) is the most abundant protein of the outer mitochondrial membrane and constitutes the major pathway for the transport of ADP, ATP, and other metabolites. In this multidisciplinary study we combined solid-state NMR, electrophysiology, and molecular dynamics simulations, to study the structure of the human VDAC isoform 2 in a lipid bilayer environment. We find that the structure of hVDAC2 is similar to the structure of hVDAC1, in line with recent investigations on zfVDAC2. However, hVDAC2 appears to exhibit an increased conformational heterogeneity compared to hVDAC1 which is reflected in broader solid-state NMR spectra and less defined electrophysiological profiles.

  19. NMR studies of Na+-anion association effects in polymer electrolytes

    International Nuclear Information System (INIS)

    Greenbaum, S.G.; Pak, Y.S.; Wintergill, M.C.; Fontanella, J.J.

    1988-01-01

    23 Na nuclear magnetic resonance (NMR) measurements on poly (propylene oxide) (PPO) and siloxane based polymer electrolytes containing various sodium salts at a single nominal concentration are reported. In addition, differential scanning calorimetry (DSC) and electrical conductivity studies were carried out on the PPO materials. The NMR-determined mobile Na + concentrations and DSC results provide evidence for ionic aggregation effects which, for some samples, result in salt precipitation at elevated temperatures. 23 Na chemical shifts observed in solid state NMR due to mobile Na + -anion interactions influence ionic transport as well as the number of available carriers. (author). 19 refs.; 7 figs

  20. Applications of NMR to studies of tissue metabolism

    International Nuclear Information System (INIS)

    Avison, M.J.; Hetherington, H.P.; Shulman, R.G.

    1986-01-01

    From its beginnings as a tool for the elucidation of biochemical pathways and bioenergetic status in unicellular organisms, the field of NMR studie in vivo has grown to encompass not only the study of isolated perfused organs, but also the study of various aspects of the biochemistry, physiology, and pathophysiology of these same organs in the intact animal. In recent years several groups have begun to extend the techniques developed in animals to the study of clinically relevant conditions in humans. A comprehensive review of all areas of NMR studies in vivo would be either unacceptably long or very superficial. For this reason the authors have restricted this review to studies published since 1980, except where an earlier study is particularly relevant to the topic under discussion. Furthermore, they have concentrated on areas that have been extending the scope of NMR in vivo. One specific omission is review of NMR studies of tumors, since a comprehensive review has recently appeared

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  2. Tautomerism and the Protonation/Deprotonation of Isocytosine in Liquid- and Solid-States Studied by NMR Spectroscopy and Theoretical Calculations

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Jansa, Petr; Ahonen, K.; Buděšínský, Miloš

    -, č. 8 (2011), s. 1544-1551 ISSN 1434-193X R&D Projects: GA AV ČR KJB400550903; GA MŠk 1M0508 Grant - others:AV ČR(CZ) M200380901 Institutional research plan: CEZ:AV0Z40550506 Keywords : NMR spectroscopy * tautomerism * nitrogen heterocycles * density functional calculations Subject RIV: CC - Organic Chemistry Impact factor: 3.329, year: 2011

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

  4. Some double resonance and multiple quantum NMR studies in solids

    Energy Technology Data Exchange (ETDEWEB)

    Wemmer, D.E.

    1978-08-01

    The first section of this work presents the theory and experimental applications to analysis of molecular motion of chemical shielding lineshapes obtained with high resolution double resonance NMR techniques. Analysis of /sup 13/C powder lineshapes in hexamethylbenzene (HMB) and decamethylferrocene (DMFe) show that these molecules reorient in a jumping manner about the symmetry axis. Analysis of proton chemical shielding lineshapes of residual protons in heavy ice (D/sub 2/O) show that protons are exchanged among the tetrahedral positions of neighboring oxygen atoms, consistent with motion expected from defect migration. The second section describes the application of Fourier Transform Double Quantum NMR to measurement of chemical shielding of deuterium in powder samples. Studies of partially deuterated benzene and ferrocene give equal shielding anisotropies, ..delta..sigma = -6.5 ppM. Theoretical predictions and experimental measurements of dipolar couplings between deuterons using FTDQ NMR are presented. Crystals of BaClO/sub 3/.D/sub 2/O, ..cap alpha..,..beta.. d-2 HMB and ..cap alpha..,..beta..,..gamma.. d-3 HMB were studied, as were powders of d-2 HMB and anisic acid. The third section discusses general multiple quantum spectroscopy in dipolar coupled spin systems. Theoretical description is made for creation and detection of coherences between states without quantum number selection rules ..delta..m = +-1. Descriptions of techniques for partial selectivity of order in preparation and detection of multiple quantum coherences are made. The effects on selectivity and resolution of echo pulses during multiple quantum experiments are discussed. Experimental observation of coherences up to order 6 have been made in a sample of benzene dissolved in a liquid crystal. Experimental verifications of order selection and echo generation have been made.

  5. NMR spectroscopic studies of membrane-bound biological systems

    International Nuclear Information System (INIS)

    Hohlweg, W.

    2013-01-01

    In the course of this thesis, biological NMR spectroscopy was employed in studying membrane-bound peptides and proteins, for which structural information is still comparatively hard to obtain. Initial work focused on various model peptides bound to membrane-mimicking micelles, studying the protonation state of arginine in a membrane environment. Strong evidence for a cation-π complex was found in TM7, a peptide which forms the seventh transmembrane helix of subunit a of the vacuolar-type H+-ATPase (V-ATPase). V-ATPase is a physiologically highly relevant proton pump, which is present in intracellular membranes of all eukaryotic organisms, as well as the plasma membrane of several specialized cells. Loss of functional V-ATPase is associated with human diseases such as osteopetrosis, distal renal tubular acidosis or the spreading of cancer. V-ATPase is considered a potential drug target in the treatment of osteoporosis and cancer, or in the development of novel contraceptives. Results from NMR solution structure determination, NMR titration experiments, paramagnetic relaxation enhancement experiments and tryptophan fluorescence spectroscopy confirm the existence of a buried cation-? complex formed between arginine residue R735, which is essential for proton transport, and neighbouring tryptophan and tyrosine residues. In vivo experiments in the yeast Saccharomyces cerevisiae using selective growth tests and fluorescence microscopy showed that formation of the cation-π complex is essential for V-ATPase function. Deletion of both aromatic residues, as well as only the one tryptophan residue leads to growth defects and inability to maintain vacuolar pH homeostasis. These findings shine new light on the still elusive mechanism of proton transport in V-ATPase, and show that arginine R735 may be directly involved in proton transfer across the membrane. (author) [de

  6. Some double resonance and multiple quantum NMR studies in solids

    International Nuclear Information System (INIS)

    Wemmer, D.E.

    1978-08-01

    The first section of this work presents the theory and experimental applications to analysis of molecular motion of chemical shielding lineshapes obtained with high resolution double resonance NMR techniques. Analysis of 13 C powder lineshapes in hexamethylbenzene (HMB) and decamethylferrocene (DMFe) show that these molecules reorient in a jumping manner about the symmetry axis. Analysis of proton chemical shielding lineshapes of residual protons in heavy ice (D 2 O) show that protons are exchanged among the tetrahedral positions of neighboring oxygen atoms, consistent with motion expected from defect migration. The second section describes the application of Fourier Transform Double Quantum NMR to measurement of chemical shielding of deuterium in powder samples. Studies of partially deuterated benzene and ferrocene give equal shielding anisotropies, Δsigma = -6.5 ppM. Theoretical predictions and experimental measurements of dipolar couplings between deuterons using FTDQ NMR are presented. Crystals of BaClO 3 .D 2 O, α,β d-2 HMB and α,β,γ d-3 HMB were studied, as were powders of d-2 HMB and anisic acid. The third section discusses general multiple quantum spectroscopy in dipolar coupled spin systems. Theoretical description is made for creation and detection of coherences between states without quantum number selection rules Δm = +-1. Descriptions of techniques for partial selectivity of order in preparation and detection of multiple quantum coherences are made. The effects on selectivity and resolution of echo pulses during multiple quantum experiments are discussed. Experimental observation of coherences up to order 6 have been made in a sample of benzene dissolved in a liquid crystal. Experimental verifications of order selection and echo generation have been made

  7. Lateral interactions in the photoreceptor membrane: a NMR study

    International Nuclear Information System (INIS)

    Mollevanger, L.C.P.J.

    1987-01-01

    The photoreceptor membrane has an exceptionally high content of polyunsaturated fatty acyl chains combined with a high amount of phosphatidyl ethanolamine. It is situated in a cell organelle, the rod outer segment, with a high biological activity in which controlable trans-membrane currents of different ions play an important role. These characteristics make it a very interesting biological membrane to search for the existence of non-bilayer structures. Therefore in this thesis a detailed study of the polymorphic phase behaviour of the rod outer segment photoreceptor lipids was undertaken, concerning modulation of the polymorphic phase behaviour of photoreceptor membrane lipids by divalent cations and temperature, polymorphism of the individual phospholipid classes phosphatidylethanolamine and phosphatidylserine and effects of cholesterol, bilayer stabilization by (rhod)opsin. Morphologically intact rod outer segment possesses a large magnetic anisotropy. This property is used to obtain 31 P-NMR of oriented photoreceptor membranes which allows spectral analysis and identification of individual phospholipid classes, and allows to study lateral lipid diffusion in intact disk membranes. The power of high resolution solid state 13 C-NMR to study the conformation of the chromophore in rhodopsin is demonstrated. (Auth.)

  8. 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...

  9. Structural studies of SpoIIAA using NMR

    International Nuclear Information System (INIS)

    Comfort, D.M.

    1998-01-01

    The protein SpoIIAA participates, via phosphorylation and dephosphorylation, in the four-component system that regulates the sporulation sigma factor e. Differential gene expression depends on specialised transcription factors called sigma factors, which direct the RNA polymerase to transcribe specific genes in one or other of the two chambers at various stages of sporulation. The first sporulation-specific sigma factor to be activated is 4 transcription that depends on σ F is essential for the remaining sigma factors to become active in turn. Early in sporulation SpoIIAA is in the phosphorylated state (SpoIIAA-P), as a result of the activity of the ATP-dependent protein kinase, SpoIIAB. About 80 minutes after the initiation of sporulation a specific phosphatase, SpoIIE, begins to hydrolyse SpoIIAA-P, and the resulting SpoIIAA again becomes a substrate for SpoIIAB. SpoIIAB is also an anti-sigma factor which in its free form inhibits a F by binding to it. Competition by SpoIIAA (the anti-anti-sigma factor) for binding to SpoIIAB releases e activity. The three-dimensional structure of SpoIIAA has been determined using high resolution NMR. SpoIIAA has a novel fold, composed of a-helices and P-strand elements. The structural differences between SpoIIAA and its inactive form, SpoIIAA-P, were also investigated by NMR. Tentative evidence points to the observation that phosphorylation of SpoIIAA results in a minor conformational change near the site of phosphorylation, which interferes with the hydrophobic interaction between SpoIIAA and SpoIIAB. Further NMR studies helped to predict the location of SpoIIAA-, GTP-, and ATP-binding sites on the SpoIIAA structure. In addition, the automated iterative NOE assignment algorithm, ARIA, was used to obtain additional NOE-based distance constraints and to calculate a refined structure. (author)

  10. NMR studies of actinide carbide and nitride electronic properties

    International Nuclear Information System (INIS)

    Boutard, Jean-Louis

    1976-12-01

    N.M.R. studies applied to 13 C and 15 N in the solid solutions ThCsub(1-x)Nsub(x), UCsub(1-x)Nsub(x) and in the compounds ThCsub(1-x) and U 2 C 3 , were undertaken to study carbon and nitrogen contribution to chemical bonds and magnetism. For THORIUM MONOCARBIDE AND CARBONITRIDE: ThCsub(1-x) and ThCsub(1-x)Nsub(x), the very strong orbital contribution to the frequency shift reveals an important covalent character of the valence band 6d metal and 2p metalloid states. The ThCsub(1-x) band structure stoichiometry variation is due to 6dγ metal states appearing at the Fermi level and is in-opposition to a rigid band model. A non-saturated bond mechanism is suggested. For URANIUM CARBONITRIDE: UCsub(1-x)Nsub(x), in the concentration range in which no magnetic order appears at low temperature (x<0.90), the results are in opposition to a localized 5f 2 configuration model, and show that the uranium fundamental state is non-magnetic. Nevertheless two qualitatively different behaviors exist: nitrogen concentration lower than 40%: and nitrogen concentration higher than 40%. A model is proposed to account for those domains: it relies on the 5f-2p hybridization parameter which is maximum on 2p band edge (UC) and almost nul for UN. For URANIUM SESQUICARBIDE: U 2 C 3 : the N.M.R. line observation at 4.2 K indicates a non-magnetic fundamental state although the magnetic susceptibility presents a maximum at 60 K. Spin fluctuations in 5f bands are proposed to describe the electronic properties of this compound. [fr

  11. 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.

  12. Some nitrogen-14 NMR studies in solids

    International Nuclear Information System (INIS)

    Pratum, T.K.

    1983-11-01

    The first order quadrupolar perturbation of the 14 N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long 14 N longitudinal relaxation times (T 1 ) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between 14 N and 1 H. Using quadrupolar echo and CP techniques, the 14 N quadrupolar coupling constants (e 2 qQ/h) and asymmetry parameters (eta) have been obtained for a variety of tetraalkylammonium compounds by observation of their quadrupolar powder patterns at various temperatures. For choline chloride and iodide the 14 N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects

  13. An extrapolation scheme for solid-state NMR chemical shift calculations

    Science.gov (United States)

    Nakajima, Takahito

    2017-06-01

    Conventional quantum chemical and solid-state physical approaches include several problems to accurately calculate solid-state nuclear magnetic resonance (NMR) properties. We propose a reliable computational scheme for solid-state NMR chemical shifts using an extrapolation scheme that retains the advantages of these approaches but reduces their disadvantages. Our scheme can satisfactorily yield solid-state NMR magnetic shielding constants. The estimated values have only a small dependence on the low-level density functional theory calculation with the extrapolation scheme. Thus, our approach is efficient because the rough calculation can be performed in the extrapolation scheme.

  14. DNP-enhanced solid-state NMR spectroscopy of active pharmaceutical ingredients.

    Science.gov (United States)

    Zhao, Li; Pinon, Arthur C; Emsley, Lyndon; Rossini, Aaron J

    2017-11-28

    Solid-state NMR spectroscopy has become a valuable tool for the characterization of both pure and formulated active pharmaceutical ingredients (APIs). However, NMR generally suffers from poor sensitivity that often restricts NMR experiments to nuclei with favorable properties, concentrated samples, and acquisition of one-dimensional (1D) NMR spectra. Here, we review how dynamic nuclear polarization (DNP) can be applied to routinely enhance the sensitivity of solid-state NMR experiments by one to two orders of magnitude for both pure and formulated APIs. Sample preparation protocols for relayed DNP experiments and experiments on directly doped APIs are detailed. Numerical spin diffusion models illustrate the dependence of relayed DNP enhancements on the relaxation properties and particle size of the solids and can be used for particle size determination when the other factors are known. We then describe the advanced solid-state NMR experiments that have been enabled by DNP and how they provide unique insight into the molecular and macroscopic structure of APIs. For example, with large sensitivity gains provided by DNP, natural isotopic abundance, 13 C- 13 C double-quantum single-quantum homonuclear correlation NMR spectra of pure APIs can be routinely acquired. DNP also enables solid-state NMR experiments with unreceptive quadrupolar nuclei such as 2 H, 14 N, and 35 Cl that are commonly found in APIs. Applications of DNP-enhanced solid-state NMR spectroscopy for the molecular level characterization of low API load formulations such as commercial tablets and amorphous solid dispersions are described. Future perspectives for DNP-enhanced solid-state NMR experiments on APIs are briefly discussed. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Solid state .sup.13 ./sup.C NMR and DFT quantum-chemical study of polymer electrolyte poly(2-ethyl-2-oxazoline)/AgCF .sub.3 ./sub.SO.sub.3 ./sub

    Czech Academy of Sciences Publication Activity Database

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

    2005-01-01

    Roč. 38, č. 12 (2005), s. 5083 -5087 ISSN 0024-9297 R&D Projects: GA AV ČR(CZ) IAA4050209 Keywords : polymer electrolyte poly(2-ethyl-2-oxazoline)/AgCF3SO3 * solid state NMR * DFT calculations Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.024, year: 2005

  16. Structural study of pyrones by NMR

    International Nuclear Information System (INIS)

    Mandarino, D.G.

    1985-01-01

    Extracts of two species of Aniba, designed Aniba-SA (light petroleum extract) and Aniba-SB (benzene extract), afforded by chromatographic fraccionation some compounds. The isolated compounds were identified using spectrometric data and C 13 -NMR coupled and decompled spectra of pyrones were registered. Measurement of the heteronuclear residual coupling by irradiation proton frequency off-resonance was used for distinguish C-5, C-7 and C-8 carbons of the pyrones SB-1, SB-3, SB-4 and SB-5. (M.J.C.) [pt

  17. Advances in 27Al MAS NMR studies of geopolymers

    Czech Academy of Sciences Publication Activity Database

    Brus, Jiří; Abbrent, Sabina; Kobera, Libor; Urbanová, Martina; Cuba, P.

    2016-01-01

    Roč. 88, č. 2016 (2016), s. 79-147 ISSN 0066-4103 R&D Projects: GA ČR(CZ) GA13-24155S; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : geopolymers * aluminosilicates * solid-state NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.600, year: 2016

  18. Theory and Applications of Solid-State NMR Spectroscopy to Biomembrane Structure and Dynamics

    Science.gov (United States)

    Xu, Xiaolin

    Solid-state Nuclear Magnetic Resonance (NMR) is one of the premiere biophysical methods that can be applied for addressing the structure and dynamics of biomolecules, including proteins, lipids, and nucleic acids. It illustrates the general problem of determining the average biomolecular structure, including the motional mean-square amplitudes and rates of the fluctuations. Lineshape and relaxtion studies give us a view into the molecular properties under different environments. To help the understanding of NMR theory, both lineshape and relaxation experiments are conducted with hexamethylbezene (HMB). This chemical compound with a simple structure serves as a perfect test molecule. Because of its highly symmetric structure, its motions are not very difficult to understand. The results for HMB set benchmarks for other more complicated systems like membrane proteins. After accumulating a large data set on HMB, we also proceed to develop a completely new method of data analysis, which yields the spectral densities in a body-fixed frame revealing internal motions of the system. Among the possible applications of solid-state NMR spectroscopy, we study the light activation mechanism of visual rhodopsin in lipid membranes. As a prototype of G-protein-coupled receptors, which are a large class of membrane proteins, the cofactor isomerization is triggered by photon absorption, and the local structural change is then propagated to a large-scale conformational change of the protein. Facilitation of the binding of transducin then passes along the visual signal to downstream effector proteins like transducin. To study this process, we introduce 2H labels into the rhodopsin chromophore retinal and the C-terminal peptide of transducin to probe the local structure and dynamics of these two hotspots of the rhodopsin activation process. In addition to the examination of local sites with solid-state 2H NMR spectroscopy, wide angle X-ray scattering (WAXS) provides us the chance of

  19. 31P Solid-state MAS NMR spectra

    International Nuclear Information System (INIS)

    Grobet, P.J.; Geerts, H.; Martens, J.A.; Jacobs, P.A.

    1989-01-01

    The structures of the silicoaluminiophosphates MCM-1 and MCM9 were characterized by 27 Al and 31 P MAS NMR. The structural identity of MCM-1 and its silicon-free homologue AlPO 4 -H 3 is demonstrated. The presence of a structural mixture in MCM-9 is confirmed. 31 P MAS NMR spectra of MCM-9 could be interpreted as a superposition of spectra of VPI-5, AlPO 4 -H 3 and SAPO-11 phases. (author). 12 refs.; 3 figs.; 1 tab

  20. A Toolbox of Solid-State NMR Experiments for the Characterization of Soft Organic Nanomaterials

    KAUST Repository

    Straasø, Lasse Arnt

    2016-02-02

    Determining how organic molecules self-assemble into a solid material is a challenging and demanding task if a single crystal of the material cannot be produced. Solid-state NMR spectroscopy offers access to such molecular details via an appropriate selection of techniques. This report gives a selected overview of 1D and 2D solid-state NMR techniques for elucidating the structure of soft organic solids. We focus on how the solid-state NMR techniques are designed from the perspective of the different nuclear interactions, using average Hamiltonian theory and product operators. We also introduce recent methods for quantification and reduction of experimental artifacts. Finally, we highlight how the solid-state NMR techniques can be applied to soft organic materials by reviewing recent applications to semicrystalline polymers, π-conjugated polymers, natural silk, and graphene-related materials.

  1. A Toolbox of Solid-State NMR Experiments for the Characterization of Soft Organic Nanomaterials

    KAUST Repository

    Straasø , Lasse Arnt; Saleem, Qasim; Hansen, Michael Ryan

    2016-01-01

    Determining how organic molecules self-assemble into a solid material is a challenging and demanding task if a single crystal of the material cannot be produced. Solid-state NMR spectroscopy offers access to such molecular details via an appropriate selection of techniques. This report gives a selected overview of 1D and 2D solid-state NMR techniques for elucidating the structure of soft organic solids. We focus on how the solid-state NMR techniques are designed from the perspective of the different nuclear interactions, using average Hamiltonian theory and product operators. We also introduce recent methods for quantification and reduction of experimental artifacts. Finally, we highlight how the solid-state NMR techniques can be applied to soft organic materials by reviewing recent applications to semicrystalline polymers, π-conjugated polymers, natural silk, and graphene-related materials.

  2. Mapping of unfolding states of integral helical membrane proteins by GPS-NMR and scattering techniques

    DEFF Research Database (Denmark)

    Calcutta, Antonello; Jessen, Christian M; Behrens, Manja Annette

    2012-01-01

    induced by unfolding of an integral membrane protein, namely TFE-induced unfolding of KcsA solubilized by the n-dodecyl ß-d-maltoside (DDM) surfactant is investigated by the recently introduced GPS-NMR (Global Protein folding State mapping by multivariate NMR) (Malmendal et al., PlosONE 5, e10262 (2010......)) along with dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). GPS-NMR is used as a tool for fast analysis of the protein unfolding processes upon external perturbation, and DLS and SAXS are used for further structural characterization of the unfolding states. The combination allows...

  3. Dynamic membrane interactions of antibacterial and antifungal biomolecules, and amyloid peptides, revealed by solid-state NMR spectroscopy.

    Science.gov (United States)

    Naito, Akira; Matsumori, Nobuaki; Ramamoorthy, Ayyalusamy

    2018-02-01

    A variety of biomolecules acting on the cell membrane folds into a biologically active structure in the membrane environment. It is, therefore, important to determine the structures and dynamics of such biomolecules in a membrane environment. While several biophysical techniques are used to obtain low-resolution information, solid-state NMR spectroscopy is one of the most powerful means for determining the structure and dynamics of membrane bound biomolecules such as antibacterial biomolecules and amyloidogenic proteins; unlike X-ray crystallography and solution NMR spectroscopy, applications of solid-state NMR spectroscopy are not limited by non-crystalline, non-soluble nature or molecular size of membrane-associated biomolecules. This review article focuses on the applications of solid-state NMR techniques to study a few selected antibacterial and amyloid peptides. Solid-state NMR studies revealing the membrane inserted bent α-helical structure associated with the hemolytic activity of bee venom melittin and the chemical shift oscillation analysis used to determine the transmembrane structure (with α-helix and 3 10 -helix in the N- and C-termini, respectively) of antibiotic peptide alamethicin are discussed in detail. Oligomerization of an amyloidogenic islet amyloid polypeptide (IAPP, or also known as amylin) resulting from its aggregation in a membrane environment, molecular interactions of the antifungal natural product amphotericin B with ergosterol in lipid bilayers, and the mechanism of lipid raft formation by sphingomyelin studied using solid state NMR methods are also discussed in this review article. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. NMR study of the molecular nanomagnet [Fe8(N3C6H15)6O2(OH)12]·[Br8·9H2O] in the high-spin magnetic ground state

    International Nuclear Information System (INIS)

    Furukawa, Y.; Kumagai, K.; Lascialfari, A.; Aldrovandi, S.; Borsa, F.; Sessoli, R.; Gatteschi, D.

    2001-01-01

    The magnetic molecular cluster [Fe 8 (N 3 C 6 H 15 ) 6 O 2 (OH) 12 ] 8+ [Br 8 ·9H 2 O] 8- , in short Fe8, has been investigated at low temperature by 1 H-NMR and relaxation measurements. Some measurements of 2 D-NMR in partially deuterated Fe8 clusters will also be reported. Upon decreasing temperature the NMR spectra display a very broad and structured signal which is the result of the internal local fields at the proton sites due to the local moments of the Fe(III) ions in the total S=10 magnetic ground state. The proton and deuteron NMR spectra have been analyzed and the different resonance peaks have been attributed to the different proton groups in the molecule. The simulation of the spectra by using a dipolar hyperfine field and the accepted model for the orientation of the Fe(III) local moments do not agree with the experiments even when the magnitude of the local Fe(III) moments is allowed to vary. It is concluded that a positive contact hyperfine interaction of the same order of magnitude as the dipolar interaction is present for all proton sites except the water molecules. The temperature and magnetic field dependence of the nuclear spin-lattice relaxation rate is ascribed to the fluctuations of the local Fe(III) moments, which follow rigidly the fluctuations of the total ground state magnetization of the nanomagnet. By using a simple model already utilized for the Mn12 cluster, we derive the value of the spin phonon coupling constant which determines the lifetime broadening of the different magnetic quantum number m substates of the S=10 ground state. It is shown that the lifetime broadening decreases rapidly on lowering the temperature. When the lifetime becomes longer than the reciprocal of the frequency shift of the proton lines a structure emerges in the NMR spectrum reflecting the ''frozen'' local moment configuration

  5. Molecular Dynamics and Morphology of High Performance Elastomers and Fibers by Solid State NMR

    Science.gov (United States)

    2016-06-30

    nuclear magnetic resonance (ssNMR) spectroscopy to investigate the chemical structure and physical state of the residual phosphorous in PBO fiber...ssNMR) spectroscopy to investigate the chemical structure and physical state of the residual phosphorous in PBO fiber, which has been long suspected to...Jason Cain, Jian H. Yu, David Veysset, Keith A. Nelson . Probing the Influence of Molecular Dynamics of Matrix Elastomers on Ballistic Impact Back-face

  6. 15N NMR studies of layered nitride superconductor LixZrNCl

    International Nuclear Information System (INIS)

    Tou, H.; Oshiro, S.; Kotegawa, H.; Taguchi, Y.; Kishiume, Y.; Kasahara, Y.; Iwasa, Y.

    2010-01-01

    NMR measurements were carried out on pristine ZrNCl and Li x ZrNCl. From the 15 N-Knight shift study, the isotropic Knight shift, the traceless chemical (orbital) shift tensor and the traceless Knight shift tensor were determined as K iso = -71 ppm, (σ 1 , σ 2 , σ 3 ) = (-55, -55, 110) ppm and (K 1 , K 2 , K 3 ) = (48, 48, -96) ppm, respectively. In the superconducting state, the fractional change of the 15 N NMR shift for H-parallel ab was observed, evidencing that the pairing symmetry is a spin-singlet state.

  7. 13C and 31P NMR studies of myocardial metabolism

    International Nuclear Information System (INIS)

    Laughlin, M.R.

    1988-01-01

    The fluxes through two enzyme systems have been measured in perfused or in in vivo heart using NMR: phosphocreatine kinase, and glycogen synthase and phosphorylase. The rates of synthesis and degradation of glycogen were monitored in vivo in fed, fasted, and diabetic rat heart during infusions of 13 C-1-glucose and insulin using proton-decoupled 13 C-NMR at 1.9 and 4.7 tesla. The enzyme activities of glycogen synthase and glycogen phosphorylase were also measured in this tissue which had been freeze clamped at the end of the experiment, for comparison with the synthetic rates. For normal fed, fasted, and diabetic animals, synthesis rates were 0.28, 0.16, and 0.15 μmol/min.gww respectively. Glycogen synthase i activity was 0.23, 0.14, and 0.14 μmol/min.gww in these hearts at the end of the experiment, when measured at appropriate substrate and activator concentrations, and follow activation time courses that are consistent with being the main rate determinant for net synthesis in all cases. Turnover of glycogen was studied by observing the preformed 13 C-1-glycogen signal during infusion of 12 C-glucose and insulin, and was found to be close to zero. Extracted phosphorylase a activity was approximately ten times that of synthase i under these circumstances. In order to fully interpret the turnover studies, glycogenolysis of preformed 13 C-glycogen was observed after a bolus of glucagon. The glycogen had either been synthesized from 13 C-1-glucose for a single hour, or during an hour of 13 C-glucose and a subsequent hour of 12 C-glucose infusion. The author observed that breakdown follows an exponential time course related to the phosphorylase a activation state and that the last synthesized glycogen breaks down at the rate of 2.5 μmol/min.gww, five times faster than that synthesized an hour earlier

  8. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen Bengaard; Andersen, Morten D.; Jakobsen, Hans Jørgen

    2006-01-01

    for the C-S-H phase formed during hydration. It will be demonstrated that Al3+ and flouride guest-ions in the anhydrous and hydrated calcium silicates can be studied in detail by 27Al and 19F MAS NMR, thereby providing information on the local structure and the mechanisms for incorporation of these ions......Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the first......- and second-coordination spheres of the spin nucleus under investigation while it is less sensitive to long-range order. Thus, crystalline as well as amorphous phases can be detected in a quantitative manner by solid-state NMR. In particular the structure of the calcium-silicate-hydrate (C-S-H) phase have...

  9. Application of Solution NMR Spectroscopy to Study Protein Dynamics

    Directory of Open Access Journals (Sweden)

    Christoph Göbl

    2012-03-01

    Full Text Available Recent advances in spectroscopic methods allow the identification of minute fluctuations in a protein structure. These dynamic properties have been identified as keys to some biological processes. The consequences of this structural flexibility can be far‑reaching and they add a new dimension to the structure-function relationship of biomolecules. Nuclear Magnetic Resonance (NMR spectroscopy allows the study of structure as well as dynamics of biomolecules in a very broad range of timescales at atomic level. A number of new NMR methods have been developed recently to allow the measurements of time scales and spatial fluctuations, which in turn provide the thermodynamics associated with the biological processes. Since NMR parameters reflect ensemble measurements, structural ensemble approaches in analyzing NMR data have also been developed. These new methods in some instances can even highlight previously hidden conformational features of the biomolecules. In this review we describe several solution NMR methods to study protein dynamics and discuss their impact on important biological processes.

  10. Novel NMR tools to study structure and dynamics of biomembranes.

    Science.gov (United States)

    Gawrisch, Klaus; Eldho, Nadukkudy V; Polozov, Ivan V

    2002-06-01

    Nuclear magnetic resonance (NMR) studies on biomembranes have benefited greatly from introduction of magic angle spinning (MAS) NMR techniques. Improvements in MAS probe technology, combined with the higher magnetic field strength of modern instruments, enables almost liquid-like resolution of lipid resonances. The cross-relaxation rates measured by nuclear Overhauser enhancement spectroscopy (NOESY) provide new insights into conformation and dynamics of lipids with atomic-scale resolution. The data reflect the tremendous motional disorder in the lipid matrix. Transfer of magnetization by spin diffusion along the proton network of lipids is of secondary relevance, even at a long NOESY mixing time of 300 ms. MAS experiments with re-coupling of anisotropic interactions, like the 13C-(1)H dipolar couplings, benefit from the excellent resolution of 13C shifts that enables assignment of the couplings to specific carbon atoms. The traditional 2H NMR experiments on deuterated lipids have higher sensitivity when conducted on oriented samples at higher magnetic field strength. A very large number of NMR parameters from lipid bilayers is now accessible, providing information about conformation and dynamics for every lipid segment. The NMR methods have the sensitivity and resolution to study lipid-protein interaction, lateral lipid organization, and the location of solvents and drugs in the lipid matrix.

  11. Structural studies of SpoIIAA using NMR

    Energy Technology Data Exchange (ETDEWEB)

    Comfort, D.M

    1998-07-01

    The protein SpoIIAA participates, via phosphorylation and dephosphorylation, in the four-component system that regulates the sporulation sigma factor e. Differential gene expression depends on specialised transcription factors called sigma factors, which direct the RNA polymerase to transcribe specific genes in one or other of the two chambers at various stages of sporulation. The first sporulation-specific sigma factor to be activated is 4 transcription that depends on {sigma}{sup F} is essential for the remaining sigma factors to become active in turn. Early in sporulation SpoIIAA is in the phosphorylated state (SpoIIAA-P), as a result of the activity of the ATP-dependent protein kinase, SpoIIAB. About 80 minutes after the initiation of sporulation a specific phosphatase, SpoIIE, begins to hydrolyse SpoIIAA-P, and the resulting SpoIIAA again becomes a substrate for SpoIIAB. SpoIIAB is also an anti-sigma factor which in its free form inhibits a F by binding to it. Competition by SpoIIAA (the anti-anti-sigma factor) for binding to SpoIIAB releases e activity. The three-dimensional structure of SpoIIAA has been determined using high resolution NMR. SpoIIAA has a novel fold, composed of a-helices and P-strand elements. The structural differences between SpoIIAA and its inactive form, SpoIIAA-P, were also investigated by NMR. Tentative evidence points to the observation that phosphorylation of SpoIIAA results in a minor conformational change near the site of phosphorylation, which interferes with the hydrophobic interaction between SpoIIAA and SpoIIAB. Further NMR studies helped to predict the location of SpoIIAA-, GTP-, and ATP-binding sites on the SpoIIAA structure. In addition, the automated iterative NOE assignment algorithm, ARIA, was used to obtain additional NOE-based distance constraints and to calculate a refined structure. (author)

  12. Investigating the reactivity of pMDI with wood cell walls using high-resolution solution-state NMR spectroscopy

    Science.gov (United States)

    Daniel J. Yelle; John Ralph; Charles R. Frihart

    2009-01-01

    The objectives of this study are the following: (1) Use solution-state NMR to assign contours in HSQC spectra of the reaction products between pMDI model compounds and: (a) lignin model compounds, (b) milled-wood lignin, (c) ball-milled wood, (d) microtomed loblolly pine; (2) Determine where and to what degree urethane formation occurs with loblolly pine cell wall...

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

    Directory of Open Access Journals (Sweden)

    Irene D’Amico

    2010-01-01

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

  14. NMR structural studies of peptides and proteins in membranes

    Energy Technology Data Exchange (ETDEWEB)

    Opella, S J [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Chemistry

    1994-12-31

    The use of NMR methodology in structural studies is described as applicable to larger proteins, considering that the majority of membrane proteins is constructed from a limited repertoire of structural and dynamic elements. The membrane associated domains of these proteins are made up of long hydrophobic membrane spanning helices, shorter amphipathic bridging helices in the plane of the bilayer, connecting loops with varying degrees of mobility, and mobile N- and C- terminal sections. NMR studies have been successful in identifying all of these elements and their orientations relative to each other and the membrane bilayer 19 refs., 9 figs.

  15. Study of molecular movements in some organic crystals by NMR

    International Nuclear Information System (INIS)

    Alexandre, M.

    1971-01-01

    After a discussion on molecular crystals (generalities, movements within molecular solids, study of movements, complexes by charge transfer) and some specific ones (molecular complexes of trinitrobenzene or TNB), this research thesis reports the use of nuclear magnetic resonance (NMR) to study molecular movements: generalities on broadband NMR, spin relaxation and strong field network, observation of the absorption signal and measurement of the second moment. The last part reports and discusses experimental results obtained on TNB-naphthalene, on TNB-azulene, on TNB-benzothiophene, and on TNB-indole

  16. Application of solid-state tritium NMR in determining the bioactive conformation of paclitaxel

    International Nuclear Information System (INIS)

    Lin, T.

    2012-01-01

    The determination of the conformation of small molecule bound to its biological target would facilitate people to design improved drugs. This determination can be difficult due to technical limitations, as exemplified by the long standing debate on the microtubule-binding conformation of a natural anticancer drug - paclitaxel. Previous studies using X-ray crystallography and solution-state NMR failed to furnish direct information on the expected conformation. Solid-state NMR may help in this task by providing precise interatomic distances, and the selective labeling on different sites with tritium atoms enables accurate measurement of long-range distances (up to 14.4 Angstroms) owing to the high gyromagnetic ratio of this nucleus, without any structural modification of the molecule. So our project aiming at illustrating the bioactive conformation of paclitaxel consists the syntheses of 6 different paclitaxel isotopomers bearing a pair of tritium at specified positions, flowing by the preparations of corresponding microtubule-labeled paclitaxel complexes. The solid-state tritium NMR analyses of these complexes would provide key distances for determining the expected conformation. Up to now, 2 paclitaxel isotopomers have been prepared from labelling the di-brominated paclitaxel precursor and from coupling the tritiated taxane rings and the tritiated side chains, respectively. The synthetic strategy allowed us to realize the syntheses in generally high yield and good stereoselectivity. Different tritiation methods have been used, from which an isotopic enrichment of higher than 92% was obtained. The syntheses of other 4 isotopomers, together with the microtubule complexes are currently underway in our lab. (author) [fr

  17. Study of solid chemical evolution in torrefaction of different biomasses through solid-state "1"3C cross-polarization/magic angle spinning NMR (nuclear magnetic resonance) and TGA (thermogravimetric analysis)

    International Nuclear Information System (INIS)

    Rodriguez Alonso, Elvira; Dupont, Capucine; Heux, Laurent; Da Silva Perez, Denilson; Commandre, Jean-Michel; Gourdon, Christophe

    2016-01-01

    The objective of this work is to compare mass loss and chemical evolution of the solid phase, versus time, during dynamic torrefaction of different types of biomass. For this purpose, two experiments, ThermoGravimetric Analysis and solid-state "1"3C Cross-Polarization/Magic Angle Spinning Nuclear Magnetic Resonance, were run on four representative biomasses. Overall mass loss and chemical evolution of the solid phase were followed, respectively, as a function of temperature and time. Thanks to this coupled information, it was shown that the knowledge of both solid mass loss and chemical evolution is necessary to characterize torrefaction severity. Moreover, biomasses containing higher proportions of xylan lost mass faster than those containing lower proportions. Lignin showed a protecting role towards cellulose, which would lead to a faster degradation of non-woody biomasses in comparison with woody biomasses. Three parameters would have an influence on solid chemical evolution during torrefaction: xylan content in hemicellulose, lignin content in biomass, and cellulose crystallinity. - Highlights: • Torrefaction of four biomasses was studied with TGA and solid-state NMR. • Both solid mass loss and chemical evolution characterize torrefaction severity. • Biomasses containing a higher proportion of xylan lose mass faster. • Lignin shows a stronger protecting role in degradation of woody biomasses. • Xylan, lignin and crystalline cellulose values influence solid chemical evolution.

  18. Local electronic structure of TM-based alloys: a pulsed NMR study

    International Nuclear Information System (INIS)

    Guerra, D.A.

    1984-01-01

    A pulsed NMR study on several transition metal + metalloid amorphous alloys is reported. The analisis of Knight shifts and nuclear spin-lattice relaxation of metalloids indicates a dominant contribution of p-electrons in the Fermi level density of state, supporting the existence of a p-d hibridization. (author) [pt

  19. Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    different and cytolytic peptides were investigated in this work. The peptides were SPF-5506-A4 from Trichoderma sp, Conolysin-Mt1 from Conus mustelinus, and Alamethicin from Trichoderma viride. The studies employed solution and solid-state NMR spectroscopy in combination with different biophysical methods...

  20. Characterization of nonderivatized plant cell walls using high-resolution solution-state NMR spectroscopy

    Science.gov (United States)

    Daniel J. Yelle; John Ralph; Charles R. Frihart

    2008-01-01

    A recently described plant cell wall dissolution system has been modified to use perdeuterated solvents to allow direct in-NMR-tube dissolution and high-resolution solution-state NMR of the whole cell wall without derivatization. Finely ground cell wall material dissolves in a solvent system containing dimethylsulfoxide-d6 and 1-methylimidazole-d6 in a ratio of 4:1 (v/...

  1. NMR studies of the helical antiferromagnetic compound EuCo2P2

    Science.gov (United States)

    Higa, N.; Ding, Q.-P.; Kubota, F.; Uehara, H.; Yogi, M.; Furukawa, Y.; Sangeetha, N. S.; Johnston, D. C.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y.

    2018-05-01

    In EuCo2P2, 4f electron spins of Eu2+ ions order antiferromagnetically below a Néel temperature TN = 66.5 K . The magnetic structure below TN was reported to be helical with the helix axis along the c-axis from the neutron diffraction study. We report the results of 153Eu, 59Co and 31P nuclear magnetic resonance (NMR) measurements on EuCo2P2 using a single crystal and a powdered sample. In the antiferromagnetic (AFM) state, we succeeded in observing 153Eu, 59Co and 31P NMR spectra in zero magnetic field. The sharp 153Eu zero field NMR (ZF NMR) lines indicate homogeneous Eu ordered moment. The 59Co and 31P ZF NMR spectra showed an asymmetric spectral shape, indicating a distribution of the internal magnetic induction at each nuclear position. The AFM propagation vector k characterizing the helical AFM state can be determined from the internal magnetic induction at Co site. We have determined the model-independent value of the AFM propagation vector k distributed from (0, 0, 0.86)2π/c to (0, 0, 0.73)2π/c, where c is the lattice parameter.

  2. NMR studies of selective population inversion and spin clustering

    International Nuclear Information System (INIS)

    Baum, J.S.

    1986-02-01

    This work describes the development and application of selective excitation techniques in Nuclear Magnetic Resonance. Composite pulses and multiple-quantum methods are used to accomplish various goals, such as broadband and narrowband excitation in liquids, and collective excitation of groups of spins in solids. These methods are applied to a variety of problems, including non-invasive spatial localization, spin cluster size characterization in disordered solids and solid state NMR imaging

  3. Structure determination of helical filaments by solid-state NMR spectroscopy

    Science.gov (United States)

    Ahmed, Mumdooh; Spehr, Johannes; König, Renate; Lünsdorf, Heinrich; Rand, Ulfert; Lührs, Thorsten; Ritter, Christiane

    2016-01-01

    The controlled formation of filamentous protein complexes plays a crucial role in many biological systems and represents an emerging paradigm in signal transduction. The mitochondrial antiviral signaling protein (MAVS) is a central signal transduction hub in innate immunity that is activated by a receptor-induced conversion into helical superstructures (filaments) assembled from its globular caspase activation and recruitment domain. Solid-state NMR (ssNMR) spectroscopy has become one of the most powerful techniques for atomic resolution structures of protein fibrils. However, for helical filaments, the determination of the correct symmetry parameters has remained a significant hurdle for any structural technique and could thus far not be precisely derived from ssNMR data. Here, we solved the atomic resolution structure of helical MAVSCARD filaments exclusively from ssNMR data. We present a generally applicable approach that systematically explores the helical symmetry space by efficient modeling of the helical structure restrained by interprotomer ssNMR distance restraints. Together with classical automated NMR structure calculation, this allowed us to faithfully determine the symmetry that defines the entire assembly. To validate our structure, we probed the protomer arrangement by solvent paramagnetic resonance enhancement, analysis of chemical shift differences relative to the solution NMR structure of the monomer, and mutagenesis. We provide detailed information on the atomic contacts that determine filament stability and describe mechanistic details on the formation of signaling-competent MAVS filaments from inactive monomers. PMID:26733681

  4. NMR studies concerning base-base interactions in oligonucleotides

    International Nuclear Information System (INIS)

    Hoogen, Y.T. van den.

    1988-01-01

    Two main subjects are treated in the present thesis. The firsst part principally deals with the base-base interactions in single-stranded oligoribonucleotides. The second part presents NMR and model-building studies of DNA and RNA duplexes containing an unpaired base. (author). 242 refs.; 26 figs.; 24 tabs

  5. Two-dimensional NMR studies of allyl palladium complexes of ...

    Indian Academy of Sciences (India)

    Administrator

    h3-Allyl complexes are intermediates in organic synthetic reactions such as allylic alkylation and amination. There is growing interest in understanding the structures of chiral h3-allyl intermediates as this would help to unravel the mechanism of enantioselective C–C bond forming reactions. Two-dimensional NMR study is a.

  6. An NMR Protonation Study of Metal Diethylenetriaminepentaacetic Acid Complexes.

    Science.gov (United States)

    Letkeman, Peter

    1979-01-01

    This experiment is suitable for an integrated laboratory course for senior chemistry majors. It introduces the student to a study of the relative basicity of different proton accepting sites. It serves as an opportunity to learn about nmr techniques and could extend to infrared, as well. (BB)

  7. NMR study of structure of lanthanide complexes in solution

    International Nuclear Information System (INIS)

    Choppin, G.R.

    1976-01-01

    The diagnostic value PMR studies of diamagnetic lanthanide complexes to define the nature of the species in the lanthanide-pyruvate system is discussed. The use of NMR spectra of both diamagnetic and paramagnetic lanthanide complexes to obtain detailed structural information is reviewed

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

    International Nuclear Information System (INIS)

    Shakinah Salleh; Faiz Ahmad; Sobri Hussein

    2016-01-01

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

  9. NMR spectroscopy applied to the eye: Drugs and metabolic studies

    Energy Technology Data Exchange (ETDEWEB)

    Saether, Oddbjoern

    2005-07-01

    NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

  10. NMR spectroscopy applied to the eye: Drugs and metabolic studies

    International Nuclear Information System (INIS)

    Saether, Oddbjoern

    2005-01-01

    NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

  11. NMR studies of macroscopic and microscopic properties of liquid crystals

    International Nuclear Information System (INIS)

    Hughes, J.R.

    1998-03-01

    The work presented is concerned with studies of orientational order in liquid crystals and the behaviour of certain mesophases. The experimental technique used in common with all the work is deuterium NMR spectroscopy. Much of the work involves studies of the orientational order of deuteriated solute molecules dissolved in liquid crystal solvents. Chapter 1 gives an introduction to liquid crystals followed by a quantitative description of orientational order. Deuterium NMR in liquid crystals is described and an outline of the molecular field theory behind the orientational order of a rigid, biaxial solute in a uniaxial mesophase is given. In Chapter 2 a novel type of mesophase induction is studied using NMR, where a solute induces up to two extra phases in a discotic mesogen depending on its concentration. The purpose of this work is to try to gain an understanding into the mechanism of the phase induction involved. Chapter 3 is concerned primarily with the macroscopic behaviour of the nematic phase formed by a semi-rigid main-chain polymer in solution. Of particular interest is the study of the reorientation of the monodomain, once the director has been rotated with respect to the magnetic field of the NMR spectrometer. A mesogen which has been claimed to exhibit a biaxial nematic phase is studied in Chapter 4, in order to determine the symmetry of the phase using NMR. Finally, Chapter 5 deals with the differing behaviour of a liquid crystal monomer and its dimer dissolved in common nematic solvents in order to determine whether this agrees with molecular field theory. (author)

  12. Measuring 13Cβ chemical shifts of invisible excited states in proteins by relaxation dispersion NMR spectroscopy

    International Nuclear Information System (INIS)

    Lundstroem, Patrik; Lin Hong; Kay, Lewis E.

    2009-01-01

    A labeling scheme is introduced that facilitates the measurement of accurate 13 C β chemical shifts of invisible, excited states of proteins by relaxation dispersion NMR spectroscopy. The approach makes use of protein over-expression in a strain of E. coli in which the TCA cycle enzyme succinate dehydrogenase is knocked out, leading to the production of samples with high levels of 13 C enrichment (30-40%) at C β side-chain carbon positions for 15 of the amino acids with little 13 C label at positions one bond removed (∼5%). A pair of samples are produced using [1- 13 C]-glucose/NaH 12 CO 3 or [2- 13 C]-glucose as carbon sources with isolated and enriched (>30%) 13 C β positions for 11 and 4 residues, respectively. The efficacy of the labeling procedure is established by NMR spectroscopy. The utility of such samples for measurement of 13 C β chemical shifts of invisible, excited states in exchange with visible, ground conformations is confirmed by relaxation dispersion studies of a protein-ligand binding exchange reaction in which the extracted chemical shift differences from dispersion profiles compare favorably with those obtained directly from measurements on ligand free and fully bound protein samples

  13. Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state 13C NMR and solution 31P NMR spectroscopy

    International Nuclear Information System (INIS)

    Liu, Shasha; Zhu, Yuanrong; Meng, Wei; He, Zhongqi; Feng, Weiying; Zhang, Chen; Giesy, John P.

    2016-01-01

    Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state 13 C NMR and solution 31 P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O–C–O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH 3 and COO/N–C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH 3 and COO/N–C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes. - Highlights: • WEOM derived from aquatic macrophytes was characterized. • C and P in WEOM were characterized by solid 13 C NMR and solution 31 P NMR. • Degradation and transformation of macrophyte-derived C and P were investigated. • Macrophyte-derived WEOM are important source for bioavailable nutrients in lakes.

  14. Hyperpolarized 129Xe as an NMR probe for functional studies

    International Nuclear Information System (INIS)

    Wolber, J.

    2000-01-01

    The nuclear spin polarization of 129 Xe can be enhanced by several orders of magnitude using optical pumping techniques, resulting in a dramatic enhancement of the 129 Xe Nuclear Magnetic Resonance (NMR) signal. The 'hyperpolarized' gas can be used for Magnetic Resonance Imaging (MRI) of the void spaces of the lungs after introduction of the gas into the respiratory system. Furthermore, the high solubility of xenon in blood and lipids suggests the use of 129 Xe NMR for studying blood flow, permeability, perfusion and blood volume. Hyperpolarized 129 Xe MRI has the potential of combining the high sensitivity and functional information of radioactive tracer studies with the high spatial and temporal resolution of MRI. The spin-lattice relaxation time T 1 of 129 Xe in blood determines the loss of polarization during transit from the lungs to the tissue of interest. A difference in the relaxation times of xenon in oxygenated and deoxygenated blood could be used as a contrast mechanism in functional Magnetic Resonance Imaging (fMRI). In this thesis, the hyperpolarized 129 Xe T 1 in human blood is measured in vitro as a function of blood oxygenation, and the relevant relaxation mechanisms are discussed. A new and unexpected finding is that the hyperpolarized 129 Xe NMR spectrum in blood is highly sensitive to blood oxygenation. Therefore, hyperpolarized 129 Xe NMR provides a powerful means of measuring blood oxygenation quantitatively and non-invasively. The interaction of xenon with hemoglobin is responsible for an oxygen-dependent shift of the 129 Xe NMR resonance of xenon in red blood cells. Injection delivery of hyperpolarized 129 Xe in solution could be a more efficient method of administrating the gas for functional NMR studies. For this purpose, suitable biocompatible carrier media have been studied. In particular, the use of perfluorocarbon emulsions, which are already in use as blood substitutes, as delivery media for hyperpolarized 129 Xe has been investigates

  15. 11B NMR study of calcium-hexaborides

    International Nuclear Information System (INIS)

    Mean, B.J.; Lee, K.H.; Kang, K.H.; Lee, Moohee; Rhee, J.S.; Cho, B.K.

    2005-01-01

    We have performed 11 B nuclear magnetic resonance (NMR) measurements to look for microscopic evidence of the ferromagnetic state in several CaB 6 single crystals. A number of 11 B NMR resonance peaks are observed with the frequency and intensity of those peaks distinctively changing depending on the angle between the crystalline axis and a magnetic field. Analyzing this behavior, we find that the electric field gradient tensor at the boron has its principal axis perpendicular to the six cubic faces with a quadrupole resonance frequency ν Q ∼600kHz. However, the satellite resonances are found to be made of two peaks. Detailed analysis of the four composite satellite peaks confirms that there are two different boron sites with slightly different ν Q 's. This suggests that the boron octahedron cages are locally distorted. However, this distortion is not directly related to ferromagnetism. Even though the magnetization data highlight the ferromagnetic hysteresis, 11 B NMR linewidth and shift data show no clear microscopic evidence of the ferromagnetic state in several different compositions of CaB 6 single crystals

  16. Amplitudes and time scales of picosecond-to-microsecond motion in proteins studied by solid-state NMR: a critical evaluation of experimental approaches and application to crystalline ubiquitin

    International Nuclear Information System (INIS)

    Haller, Jens D.; Schanda, Paul

    2013-01-01

    Solid-state NMR provides insight into protein motion over time scales ranging from picoseconds to seconds. While in solution state the methodology to measure protein dynamics is well established, there is currently no such consensus protocol for measuring dynamics in solids. In this article, we perform a detailed investigation of measurement protocols for fast motions, i.e. motions ranging from picoseconds to a few microseconds, which is the range covered by dipolar coupling and relaxation experiments. We perform a detailed theoretical investigation how dipolar couplings and relaxation data can provide information about amplitudes and time scales of local motion. We show that the measurement of dipolar couplings is crucial for obtaining accurate motional parameters, while systematic errors are found when only relaxation data are used. Based on this realization, we investigate how the REDOR experiment can provide such data in a very accurate manner. We identify that with accurate rf calibration, and explicit consideration of rf field inhomogeneities, one can obtain highly accurate absolute order parameters. We then perform joint model-free analyses of 6 relaxation data sets and dipolar couplings, based on previously existing, as well as new data sets on microcrystalline ubiquitin. We show that nanosecond motion can be detected primarily in loop regions, and compare solid-state data to solution-state relaxation and RDC analyses. The protocols investigated here will serve as a useful basis towards the establishment of a routine protocol for the characterization of ps–μs motions in proteins by solid-state NMR

  17. Amplitudes and time scales of picosecond-to-microsecond motion in proteins studied by solid-state NMR: a critical evaluation of experimental approaches and application to crystalline ubiquitin

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Jens D.; Schanda, Paul, E-mail: paul.schanda@ibs.fr [Univ. Grenoble Alpes, Institut de Biologie Structurale (IBS) (France)

    2013-10-09

    Solid-state NMR provides insight into protein motion over time scales ranging from picoseconds to seconds. While in solution state the methodology to measure protein dynamics is well established, there is currently no such consensus protocol for measuring dynamics in solids. In this article, we perform a detailed investigation of measurement protocols for fast motions, i.e. motions ranging from picoseconds to a few microseconds, which is the range covered by dipolar coupling and relaxation experiments. We perform a detailed theoretical investigation how dipolar couplings and relaxation data can provide information about amplitudes and time scales of local motion. We show that the measurement of dipolar couplings is crucial for obtaining accurate motional parameters, while systematic errors are found when only relaxation data are used. Based on this realization, we investigate how the REDOR experiment can provide such data in a very accurate manner. We identify that with accurate rf calibration, and explicit consideration of rf field inhomogeneities, one can obtain highly accurate absolute order parameters. We then perform joint model-free analyses of 6 relaxation data sets and dipolar couplings, based on previously existing, as well as new data sets on microcrystalline ubiquitin. We show that nanosecond motion can be detected primarily in loop regions, and compare solid-state data to solution-state relaxation and RDC analyses. The protocols investigated here will serve as a useful basis towards the establishment of a routine protocol for the characterization of ps–μs motions in proteins by solid-state NMR.

  18. Impact of opal nanoconfinement on electronic properties of sodium particles: NMR studies

    Energy Technology Data Exchange (ETDEWEB)

    Charnaya, E.V., E-mail: charnaya@live.com [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Institute of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Lee, M.K. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); MoST Instrument Center at NCKU, Tainan, 70101 Taiwan (China); Chang, L.J. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Kumzerov, Yu.A.; Fokin, A.V. [A.F. Ioffe Physico-Technical Institute RAS, St. Petersburg, 194021 (Russian Federation); Samoylovich, M.I. [Moscow Institute of Physics and Technology, Moscow, 141700 (Russian Federation); Bugaev, A.S. [CSR Institute of Technology “Technomash”, Moscow, 121108 (Russian Federation)

    2015-03-20

    The {sup 23}Na Knight shift of NMR line which is highly correlated with the electron spin susceptibility and density of states at the Fermi level was studied for the sodium loaded opal. The measurements were carried out within a temperature range from 100 to 400 K for solid and melted confined sodium nanoparticles. The NMR line below 305 K was a singlet with the Knight shift reduced compared to that in bulk. Above this temperature the NMR line split reproducibly into two components with opposite trends in the Knight shift temperature dependences which evidenced a nanoconfinement-induced transformation and heterogeneity in the electron system. The findings were suggested to be related to changes in the topology of the Fermi surface.

  19. Structural investigation of e-beam cured epoxy resins through solid state NMR

    International Nuclear Information System (INIS)

    Alessi, Sabina; Spinella, Alberto; Caponetti, Eugenio; Dispenza, Clelia; Spadaro, Giuseppe

    2012-01-01

    In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artefact, are obtained by solid state NMR, carried out at constant room temperature. - Highlights: ► The structure of two e-beam cured epoxy systems is investigated through solid state NMR. ► The aim is to have direct information about the structure without inducing modifications. ► The different molecular structures are able to emphasize the response of solid state NMR. ► T 1 H, T 1ρ H and T CH measurements indicate different cross-linking degrees. ► The NMR results are in agreement with DMTA analysis performed in a previous paper.

  20. NMR backbone resonance assignments of the prodomain variants of BDNF in the urea denatured state.

    Science.gov (United States)

    Wang, Jing; Bains, Henrietta; Anastasia, Agustin; Bracken, Clay

    2018-04-01

    Brain derived neurotrophic factor (BDNF) is a member of the neurotrophin family of proteins which plays a central role in neuronal survival, growth, plasticity and memory. A single Val66Met variant has been identified in the prodomain of human BDNF that is associated with anxiety, depression and memory disorders. The structural differences within the full-length prodomain Val66 and Met66 isoforms could shed light on the mechanism of action of the Met66 and its impact on the development of neuropsychiatric-associated disorders. In the present study, we report the backbone 1 H, 13 C, and 15 N NMR assignments of both full-length Val66 and Met66 prodomains in the presence of 2 M urea. These conditions were utilized to suppress residual structure and aid subsequent native state structural investigations aimed at mapping and identifying variant-dependent conformational differences under native-state conditions.

  1. Internal protein dynamics on ps to μs timescales as studied by multi-frequency {sup 15}N solid-state NMR relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Zinkevich, Tatiana [Martin-Luther-Universität Halle-Wittenberg, NMRGroup, Faculty of Natural Sciences II, Institut für Physik (Germany); Chevelkov, Veniamin [Max-Planck-Institut für Biophysikalische Chemie (Germany); Reif, Bernd [Technische Universität München, Department Chemie (Germany); Saalwächter, Kay; Krushelnitsky, Alexey, E-mail: krushelnitsky@physik.uni-halle.de [Martin-Luther-Universität Halle-Wittenberg, NMRGroup, Faculty of Natural Sciences II, Institut für Physik (Germany)

    2013-09-19

    A comprehensive analysis of the dynamics of the SH3 domain of chicken alpha-spectrin is presented, based upon {sup 15}N T{sub 1} and on- and off-resonance T{sub 1ρ} relaxation times obtained on deuterated samples with a partial back-exchange of labile protons under a variety of the experimental conditions, taking explicitly into account the dipolar order parameters calculated from {sup 15}N–{sup 1}H dipole–dipole couplings. It is demonstrated that such a multi-frequency approach enables access to motional correlation times spanning about 6 orders of magnitude. We asses the validity of different motional models based upon orientation autocorrelation functions with a different number of motional components. We find that for many residues a “two components” model is not sufficient for a good description of the data and more complicated fitting models must be considered. We show that slow motions with correlation times on the order of 1–10 μs can be determined reliably in spite of rather low apparent amplitudes (below 1 %), and demonstrate that the distribution of the protein backbone mobility along the time scale axis is pronouncedly non-uniform and non-monotonic: two domains of fast (τ < 10{sup −10} s) and intermediate (10{sup −9} s < τ < 10{sup −7} s) motions are separated by a gap of one order of magnitude in time with almost no motions. For slower motions (τ > 10{sup −6} s) we observe a sharp ∼1 order of magnitude decrease of the apparent motional amplitudes. Such a distribution obviously reflects different nature of backbone motions on different time scales, where the slow end may be attributed to weakly populated “excited states.” Surprisingly, our data reveal no clearly evident correlations between secondary structure of the protein and motional parameters. We also could not notice any unambiguous correlations between motions in different time scales along the protein backbone emphasizing the importance of the inter

  2. NMR and XAS Study of Fe-Mo Double Perovskites

    International Nuclear Information System (INIS)

    Zajac, D.A.; Kapusta, C.; Borowiec, M.; Sikora, M.; Marquina, C.; Blasco, J.; Ibarra, M.R.

    2005-01-01

    The results of NMR and XAS measurements of the A 2 FeMoO 6 double perovskites (DP) (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) at the Fe and Mo K edges are reported and the information on the individual site electronic and magnetic properties is analysed. The compounds studied belong to the family of materials exhibiting a high field '' colossal '' magnetoresistance as well as a low field '' giant '' magnetoresistance. Magnetoresistive properties of the compounds arise from their half-metallicity, i.e. only one spin direction being populated in the conduction band, which consists of overlapping spin down 3d Fe, 2p O and 4d Mo electron bands. Within the model, a spin-down electron undergoes a fast hopping through unoccupied oxygen 2p orbitals between Fe 3+ (3d 5 - spin up) and Mo 6+ (4d 0 ) ionic cores. This mechanism implicates an anti-parallel coupling of the Fe and Mo spins and leads to non-integer magnetic moments and a metallic character below TC. The interaction, in analogy with the '' double exchange '' (DE) in manganites, is called '' double exchange-like '' interaction. The superexchange interaction (SE) is also expected to be present, resulting also in an anti-parallel coupling of 3d Fe 3+ and 4d Mo 5+ spins through occupied oxygen 2p orbitals. The insulating character of SE is connected with an increase of the tilt angle of the Fe-O-Mo bond, which is related to a change of the structural tolerance factor f and results in structural distortions. The molybdenum NMR measurements revealed the existence of a non-integer magnetic moment at Mo and Fe, which can be attributed to the DE-like interaction. However, experiments using Moessbauer spectroscopy have shown the existence of two Fe ionisation states - with integer (SE) and non integer (DE) magnetic moments. The 95 Mo and 97 Mo NMR measurements on A 2 FeMoO 6 (A 2 =Sr 2 , SrBa, Ba 2 , Ca 2 ) presented in this work show different values of the Mo hyperfine field and the corresponding magnetic moment. This is attributed

  3. Structural Characterization of Febuxostat/l-Pyroglutamic Acid Cocrystal Using Solid-State 13C-NMR and Investigational Study of Its Water Solubility

    OpenAIRE

    Ji-Hun An; Changjin Lim; Hyung Chul Ryu; Jae Sun Kim; Hyuk Min Kim; Alice Nguvoko Kiyonga; Minho Park; Young-Ger Suh; Gyu Hwan Park; Kiwon Jung

    2017-01-01

    Febuxostat (FB) is a poorly water-soluble drug that belongs to BCS class II. The drug is employed for the treatment of inflammatory disease arthritis urica (gout), and the free base, FB form-A, is most preferred for drug formulation. In order to achieve a goal of improving the water solubility of FB form-A, this study was carried out using the cocrystallization technique called the liquid-assisted grinding method to produce FB cocrystals. Here, five amino acids containing amine (NH), oxygen (...

  4. Contemporary NMR Studies of Protein Electrostatics.

    Science.gov (United States)

    Hass, Mathias A S; Mulder, Frans A A

    2015-01-01

    Electrostatics play an important role in many aspects of protein chemistry. However, the accurate determination of side chain proton affinity in proteins by experiment and theory remains challenging. In recent years the field of nuclear magnetic resonance spectroscopy has advanced the way that protonation states are measured, allowing researchers to examine electrostatic interactions at an unprecedented level of detail and accuracy. Experiments are now in place that follow pH-dependent (13)C and (15)N chemical shifts as spatially close as possible to the sites of protonation, allowing all titratable amino acid side chains to be probed sequence specifically. The strong and telling response of carefully selected reporter nuclei allows individual titration events to be monitored. At the same time, improved frameworks allow researchers to model multiple coupled protonation equilibria and to identify the underlying pH-dependent contributions to the chemical shifts.

  5. Carbon-13 solid state NMR studies in the aromatization of residual coals from hydropyrolised cellulose; Estudo por {sup 13} C RMN em estado solido da aromatizacao em carvoes residuais de celulose hidropirolisada

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, J.D.; Luengo, C.A. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica; Snape, C.A. [Dept. Pure and Apllied Chemistry, Glasgow (United Kingdom)

    1997-12-31

    Pure cellulose was pyrolyzed is a fixed-bed reactor under hydrogen pressure (hydropyrolysis). Residual chars were collected and analysed by solid state nmr {sup 13} C (CP-MAS) and elemental. Hydrophyrolysis parameters such as final temperature in the range of 300 to 520 deg C and hydrogen pressure from 5 to 100 atm gave different char samples. CP-MAS spectra were obtained in a BRUKER MSL-100 spectrometer. The results showed that the aromatic and aliphatic fractions had strong dependence with temperature and no influence with pressure. Elemental analysis indicated the carbon content increased more with temperature than the pressure increasing. (author) 6 refs., 2 figs., 2 tabs.

  6. Powder-XRD and (14) N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides.

    Science.gov (United States)

    Kempgens, Pierre; Britton, Jonathan

    2016-05-01

    Some metal nitrides (TiN, ZrN, InN, GaN, Ca3 N2 , Mg3 N2 , and Ge3 N4 ) have been studied by powder X-ray diffraction (XRD) and (14) N magic angle-spinning (MAS) solid-state NMR spectroscopy. For Ca3 N2 , Mg3 N2 , and Ge3 N4 , no (14) N NMR signal was observed. Low speed (νr  = 2 kHz for TiN, ZrN, and GaN; νr  = 1 kHz for InN) and 'high speed' (νr  = 15 kHz for TiN; νr  = 5 kHz for ZrN; νr  = 10 kHz for InN and GaN) MAS NMR experiments were performed. For TiN, ZrN, InN, and GaN, powder-XRD was used to identify the phases present in each sample. The number of peaks observed for each sample in their (14) N MAS solid-state NMR spectrum matches perfectly well with the number of nitrogen-containing phases identified by powder-XRD. The (14) N MAS solid-state NMR spectra are symmetric and dominated by the quadrupolar interaction. The envelopes of the spinning sidebands manifold are Lorentzian, and it is concluded that there is a distribution of the quadrupolar coupling constants Qcc 's arising from structural defects in the compounds studied. Copyright © 2015 John Wiley & Sons, Ltd.

  7. On the use of atomistic simulations to aid bulk metallic glasses structural elucidation with solid-state NMR.

    Science.gov (United States)

    Ferreira, Ary R; Rino, José P

    2017-08-24

    Solid-state nuclear magnetic resonance (ssNMR) experimental 27 Al metallic shifts reported in the literature for bulk metallic glasses (BMGs) were revisited in the light of state-of-the-art atomistic simulations. In a consistent way, the Gauge-Including Projector Augmented-Wave (GIPAW) method was applied in conjunction with classical molecular dynamics (CMD). A series of Zr-Cu-Al alloys with low Al concentrations were selected as case study systems, for which realistic CMD derived structural models were used for a short- and medium-range order mining. That initial procedure allowed the detection of trends describing changes on the microstructure of the material upon Al alloying, which in turn were used to guide GIPAW calculations with a set of abstract systems in the context of ssNMR. With essential precision and accuracy, the ab initio simulations also yielded valuable trends from the electronic structure point of view, which enabled an overview of the bonding nature of Al-centered clusters as well as its influence on the experimental ssNMR outcomes. The approach described in this work might promote the use of ssNMR spectroscopy in research on glassy metals. Moreover, the results presented demonstrate the possibility to expand the applications of this technique, with deeper insight into nuclear interactions and less speculative assignments.

  8. Broad line NMR study of modified polypropylene fibres

    International Nuclear Information System (INIS)

    Olcak, D.; Sevcovic, L.; Mucha, L.

    1999-01-01

    Study of drawn fibres prepared from an isostatic polypropylene modified by an ethylene aminoalkylacrylate copolymer has been done using the broad line of 1 H NMR. NMR spectra were measured on the set of fibres prepared with a draw ratio λ from 1 to 5.5 at two temperatures, one of them corresponding to the onset of segmental motion and the other one is the minddle of the temperature interval as determined by decrease of the second moment M 2 . Decomposition of the spectra into elementary components related to the amorphous, intermediate and crystalline regions of partially crystalline polymers has been made. The drawing of the fibres was found to enhance the chain mobility in the amorphous region and to restrain the molecular motion in the intermediate region. Such behaviour well supports conclusions predicted in the earlier study based on the spin-lattice relaxation time T 1 and dynamic mechanical data treated using the WLF theory. (Authors)

  9. NMR studies on graphite-methanol system

    International Nuclear Information System (INIS)

    El-Akkad, T.M.

    1977-01-01

    The nuclear magnetic relaxation times for protons of methanol on graphite have been studied. The perpendicular and the transversal magnetization as a function of temperature were measured. The results show that the presence of graphite slowed down the methanol movement compared with that in the pure alcohol, and that the methanol molecules are attached to the graphite surface via methyl groups. (author)

  10. STRUCTURAL STUDY AND INVESTIGATION OF NMR TENSORS ...

    African Journals Online (AJOL)

    NBO studies were performed to the second-order and perturbative estimates of donor-acceptor interaction have been done. The procedures of gauge-invariant atomic orbital (GIAO) and continuous-set-of-gauge-transformation (CSGT) were employed to calculate isotropic shielding, chemical shifts anisotropy and chemical ...

  11. NMR studies of defects created by irradiation in metals

    International Nuclear Information System (INIS)

    Minier, M.; Minier, C.

    1983-06-01

    Nuclear Magnetic Resonance has been rarely used to study point defects created by irradiation in metals. Information obtained in this field using N.M.R. are shown. Some results are also described: characterization of migrating defects in electron irradiated copper; mobility of the complex interstitial-impurity in Al with 150 ppm of chromium; interstitial structure in irradiated aluminum and autodiffusion in metals [fr

  12. NMR studies of electrophoretic mobility in surfactant systems

    International Nuclear Information System (INIS)

    Conveney, F.M.; Strange, J.H.; Smith, A.L.; Smith, E.G.

    1989-01-01

    An experimental technique is described in which the flow of electrically charged micelles is measured in the presence of an applied electric field using an NMR technique. The method is used to determine the electrophoretic mobility at ambient temperature of a 5% aqueous solution of sodium dodecyl sulphate and is shown to provide a new technique for the study of electrophoresis in surfactant solutions. (author). 8 refs.; 4 figs

  13. Betulinic acid spectroscopic studies by NMR

    International Nuclear Information System (INIS)

    Junges, Mario Jose; Fernandes, Joao Batista; Rodrigues Filho, Edson; Vieira, Paulo Cezar; Silva, Maria Fatima das G. Fernandes da

    1995-01-01

    HMQC, HMBC, COSY 1 H- 1 H, DEPT, COSYHLR were used to assign the hydrogen and carbon chemical shifts of betulinic acid. On base in this study it is proposed to change the δ of the carbons 6, 11, 18, 19 and 26 and of the methyls hydrogen in the literature for betulinic acid, as well as of the compounds where betulinic acid was used as model. It was verified that H-5, δ 0,82, is in position strongly shielded. (author)

  14. [Derivative spectrophotometric and NMR spectroscopic study in pharmaceutical science].

    Science.gov (United States)

    Kitamura, Keisuke

    2007-10-01

    This review starts with an introduction of derivative spectrophotometry followed by a description on the construction of a personal computer-assisted derivative spectrophotometric (DS) system. An acquisition system for inputting digitalized absorption spectra into personal computers and a BASIC program for calculating derivative spectra were developed. Then, applications of the system to drug analyses that are difficult with traditional absorption methods are described. Following this, studies on the interactions of drugs with biological macromolecules by the DS and NMR methods were discussed. An (1)H NMR study elucidated that the small unilamellar vesicle (SUV) has a single membrane made of a phosphatidylcholine bilayer, and that chlorpromazine interacts with both the outer and inner layers. (13)C NMR revealed a reduction of the dissociation constants of phenothiazine drugs due to their interaction with SUV. The partition coefficients of phenothiazine, benzodiazepine and steroid drugs in an SUV-water system and the effects of cholesterol or amino lipids content on these partition coefficients were examined by the DS method. The binding constants of phenothiazine drugs to bovine serum albumin (BSA) and the influence of Na(+), K(+), Cl(-), Br(-), and I(-) on these binding constants were determined by DS. It was found that I(-), Br(-), Cl(-) reduce the binding constants in this order, and that Na(+) and K(+) have no effect. A (19)F NMR study revealed that triflupromazine binds to BSA and human serum albumin in two regions including Site II with different populations, and that a nonsteroidal anti-inflammatory drug, niflumic acid, binds Sites Ia and Ib.

  15. Study of β-NMR for Liquid Biological Samples

    CERN Document Server

    Beattie, Caitlin

    2017-01-01

    β-NMR is an exotic form of NMR spectroscopy that allows for the characterization of matter based on the anisotropic β-decay of radioactive probe nuclei. This has been shown to be an effective spectroscopic technique for many different compounds, but its use for liquid biological samples is relatively unexplored. The work at the VITO line of ISOLDE seeks to employ this technique to study such samples. Currently, preparations are being made for an experiment to characterize DNA G-quadruplexes and their interactions with stabilizing cations. More specifically, the work in which I engaged as a summer student focused on the experiment’s liquid handling system and the stability of the relevant biological samples under vacuum.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-07-01

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

  17. Conformational, vibrational, NMR and DFT studies of N-methylacetanilide.

    Science.gov (United States)

    Arjunan, V; Santhanam, R; Rani, T; Rosi, H; Mohan, S

    2013-03-01

    A detailed conformational, vibrational, NMR and DFT studies of N-methylacetanilide have been carried out. In DFT, B3LYP method have been used with 6-31G(**), 6-311++G(**) and cc-pVTZ basis sets. The vibrational frequencies were calculated resulting in IR and Raman frequencies together with intensities and Raman depolarisation ratios. The dipole moment derivatives were computed analytically. Owing to the complexity of the molecule, the potential energy distributions of the vibrational modes of the compound are also calculated. Isoelectronic molecular electrostatic potential surface (MEP) and electron density surface were examined. (1)H and (13)C NMR isotropic chemical shifts were calculated and the assignments made are compared with the experimental values. The energies of important MO's of the compound were also determined from TD-DFT method. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. NMR relaxation studies with MnDPDP

    International Nuclear Information System (INIS)

    Southon, T.E.; Grant, D.; Bjoernerud, A.; Moen, O.M.; Spilling, B.; Martinsen, I.; Refsum, H.

    1997-01-01

    Purpose: Our studies were designed to compare the efficacy of mangafodipir trisodium (MnDPDP, Teslascan) as a tissue-specific MR agent with that of manganese chloride (MnCl 2 ), to compare the efficacy of different doses and rates of administration of MnDPDP, and to collect the data needed for predicting optimum pulse sequences. Material and Methods: The dose response for the relaxation rates R1 and R2 at 0.47 T, and the manganese (Mn) concentrations in rat liver and in the liver, pancreas, heart and adrenals of pigs was determined for both MnDPDP and MnCl 2 administered i.v. Computer simulations were carried out to model the effects of different tissue Mn concentrations and TR on signal intensities and contrast-to-noise ratios. Results: In rat liver and pig organs both compounds produced a positive dose-response in R1 and tissue Mn concentration, and only small or no response in R2. The Mn concentration in rat liver was positively correlated with R1, regardless of the form in which Mn was given, or the rate of administration. Optimal imaging parametes are therefore expected to be different pre- and post-MnDPDP administration. (orig./AJ)

  19. Structural, (197)Au Mössbauer and solid state (31)P CP/MAS NMR studies on bis (cis-bis(diphenylphosphino)ethylene) gold(I) complexes [Au(dppey)(2)]X for X = PF(6), I.

    Science.gov (United States)

    Healy, Peter C; Loughrey, Bradley T; Bowmaker, Graham A; Hanna, John V

    2008-07-28

    (197)Au Mössbauer spectra for the d(10) gold(i) phosphine complexes, [Au(dppey)(2)]X (X = PF(6), I; dppey = (cis-bis(diphenylphosphino)ethylene), and the single crystal X-ray structure and solid state (31)P CPMAS NMR spectrum of [Au(dppey)(2)]I are reported here. In [Au(dppey)(2)]I the AuP(4) coordination geometry is distorted from the approximately D(2) symmetry observed for the PF(6)(-) complex with Au-P bond lengths 2.380(2)-2.426(2) A and inter-ligand P-Au-P angles 110.63(5)-137.71(8) degrees . Quadrupole splitting parameters derived from the Mössbauer spectra are consistent with the increased distortion of the AuP(4) coordination sphere with values of 1.22 and 1.46 mm s(-1) for the PF(6)(-) and I(-) complexes respectively. In the solid state (31)P CP MAS NMR spectrum of [Au(dppey)(2)]I, signals for each of the four crystallographically independent phosphorus nuclei are observed, with the magnitude of the (197)Au quadrupole coupling being sufficiently large to produce a collapse of (1)J(Au-P) splitting from quartets to doublets. The results highlight the important role played by the counter anion in the determination of the structural and spectroscopic properties of these sterically crowded d(10) complexes.

  20. Solid state low power pulsed NMR spectrometer system

    International Nuclear Information System (INIS)

    Nadkarni, S.S.; Parthasarathy, T.G.; Menon, M.P.S.; Hannurkar, P.R.

    1981-01-01

    A pulsed nuclear magnetic resonance spectrometer system is described for relaxation time studies on solid and liquid samples. The spectrometer design is fully solid state and a special microcomputer interface is incorporated for automatic evaluation of the relaxation times. The prototype system has been designed to operate at 9 MHz, but the modular concept used in the construction permits operation at any frequency in the range 5-10 MHz. The system has a recovery time of 15 micro seconds at 9 MHz. The range of measurement for the spin-lattice relaxation time is 0.1 millisecond to 1000 seconds; for spin-spin relaxation time, the range is 14μ seconds to 100 milliseconds. (author)

  1. NMR study of rare earth and actinide complexes

    International Nuclear Information System (INIS)

    Villardi de Montlaur de, G.C.

    1978-01-01

    Proton magnetic resonance studies of lanthanide shift reagents with olefin-transition metal complexes, monoamines and diamines as substrates are described. Shift reagents for olefins are reported: Lnsup(III)(fod) 3 can induce substantial shifts in the nmr spectra of a variety of olefins when silver 1-heptafluororobutyrate is used to complex the olefin. The preparation, properties and efficiency of such systems are described. Configurational aspects and exchange processes of Lnsup(III)(fod) 3 complexes with secondary and tertiary monoamines are analysed by means of dynamic nmr. Factors influencing the stability and the stoichiometry of these complexes and various processes such as nitrogen inversion and ligand exchange are discussed. At low temperature, ring inversion can be slow on an nmr time-scale for Lnsup(III)(fod) 3 -diamino chelates. Barriers to ring inversion in substituted ethylenediamines and propanediamines are obtained. Steric factors appear to play an important role in the stability and kinetics of these bidentate species. The synthesis of uranium-IV crown-ether and cryptate complexes is described. A conformational study of these compounds show evidence of an insertion of the paramagnetic cation as witnessed by the large induced shifts observed. The insertion of uranium in the macrocyclic ligand of a UCl 4 -dicyclohexyl-18-crown-6 complex is confirmed by an X-ray structural determination [fr

  2. Sine-squared shifted pulses for recoupling interactions in solid-state NMR

    Science.gov (United States)

    Jain, Mukul G.; Rajalakshmi, G.; Equbal, Asif; Mote, Kaustubh R.; Agarwal, Vipin; Madhu, P. K.

    2017-06-01

    Rotational-Echo DOuble-Resonance (REDOR) is a versatile experiment for measuring internuclear distance between two heteronuclear spins in solid-state NMR. At slow to intermediate magic-angle spinning (MAS) frequencies, the measurement of distances between strongly coupled spins is challenging due to rapid dephasing of magnetisation. This problem can be remedied by employing the pulse-shifted version of REDOR known as Shifted-REDOR (S-REDOR) that scales down the recoupled dipolar coupling. In this study, we propose a new variant of the REDOR sequence where the positions of the π pulses are determined by a sine-squared function. This new variant has scaling properties similar to S-REDOR. We use theory, numerical simulations, and experiments to compare the dipolar recoupling efficiencies and the experimental robustness of the three REDOR schemes. The proposed variant has advantages in terms of radiofrequency field requirements at fast MAS frequencies.

  3. Influence of water on stability of geopolymers investigated by NMR solid state spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kobera, Libor; Brus, Jiří; Urbanová, Martina; Slavík, R.

    2008-01-01

    Roč. 33, - (2008), s. 86 ISSN 1896-2203. [Mid-European Clay Conference MECC 08 /4./. 22.09.2008-27.09.2008, Zakopane] R&D Projects: GA AV ČR IAA400500602 Institutional research plan: CEZ:AV0Z40500505 Keywords : stability * NMR * solid state spectroscopy * geopolymer Subject RIV: CD - Macromolecular Chemistry

  4. Describing the anisotropic 133Cs solid state NMR interactions in cesium chromate

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Brus, Jiří

    2017-01-01

    Roč. 684, 16 September (2017), s. 8-13 ISSN 0009-2614 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : NMR * DFT * solid state Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.815, year: 2016

  5. Solid state NMR investigations and MD simulations of triblock copolymers in lipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Baerenwald, R.; Ferreira, T. M.; Ollila, Samuli; Saalwaechter, K.

    2017-01-01

    Roč. 46, Suppl 1 (2017), S117 ISSN 0175-7571. [IUPAB congress /19./ and EBSA congress /11./. 16.07.2017-20.07.2017, Edinburgh] Institutional support: RVO:61388963 Keywords : solid state NMR * molecular dynamic simulations Subject RIV: BO - Biophysics

  6. High-Resolution Solid-State NMR Spectroscopy: Characterization of Polymorphism in Cimetidine, a Pharmaceutical Compound

    Science.gov (United States)

    Pacilio, Julia E.; Tokarski, John T.; Quiñones, Rosalynn; Iuliucci, Robbie J.

    2014-01-01

    High-resolution solid-state NMR (SSNMR) spectroscopy has many advantages as a tool to characterize solid-phase material that finds applications in polymer chemistry, nanotechnology, materials science, biomolecular structure determination, and others, including the pharmaceutical industry. The technology associated with achieving high resolution…

  7. Determination of binder distributions in green-state ceramics by NMR imaging

    International Nuclear Information System (INIS)

    Garrido, L.; Ackerman, J.L.; Ellingson, W.A.; Weyand, J.D.

    1988-03-01

    The manufacture of reliable high performance structural ceramics requires a good understanding of the different steps involved in the process. The presence of nonuniformities in the distribution of the polymeric binder could give rise to local fluctuations of density that could produce failure of the ceramic piece. Specimens prepared from Al 2 O 3 with 15 and 2.5% ww binder were imaged using NMR in order to measure binder distribution maps. Results show that NMR imaging could be a useful technique to nondestructively evaluate the quality of green-state specimens. 5 refs., 5 figs

  8. 'In vivo' and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study

    International Nuclear Information System (INIS)

    Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R.

    1995-01-01

    This work has developed a study on transgenic plants using two different techniques of nuclear magnetic resonance, in vivo NMR and high resolution NMR. In order to understand the gene mutations and characterize the plants constituents, NMR spectral data were analysed and discussed, then the results were presented

  9. Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    Monica Ferro

    2017-01-01

    Full Text Available Two different formulations of cyclodextrin nanosponges (CDNS, obtained by polycondensation of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn, were treated with aqueous solutions of ibuprofen sodium salt (IbuNa affording hydrogels that, after lyophilisation, gave two solid CDNS-drug formulations. 1H fast MAS NMR and 13C CP-MAS NMR spectra showed that IbuNa was converted in situ into its acidic and dimeric form (IbuH after freeze-drying. 13C CP-MAS NMR spectra also indicated that the structure of the nanosponge did not undergo changes upon drug loading compared to the unloaded system. However, the 13C NMR spectra collected under variable contact time cross-polarization (VCT-CP conditions showed that the polymeric scaffold CDNS changed significantly its dynamic regime on passing from the empty CDNS to the drug-loaded CDNS, thus showing that the drug encapsulation can be seen as the formation of a real supramolecular aggregate rather than a conglomerate of two solid components. Finally, the structural features obtained from the different solid-state NMR approaches reported matched the information from powder X-ray diffraction profiles.

  10. Solid-State NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization

    International Nuclear Information System (INIS)

    Takahashi, Hiroki; Bardet, Michel; De Paepe, Gael; Hediger, Sabine; Ayala, Isabel; Simorre, Jean-Pierre

    2013-01-01

    Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool. (authors)

  11. Solid-state NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization.

    Science.gov (United States)

    Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine

    2013-04-03

    Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bevilaqua, Rochele C. A.; Miranda, Caetano R. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Rigo, Vagner A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Universidade Tecnológica Federal do Paraná, UTFPR, Cornélio Procópio, PR (Brazil); Veríssimo-Alves, Marcos [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Departamento de Física, ICEx, Universidade Federal Fluminense, UFF, Volta Redonda, RJ (Brazil)

    2014-11-28

    The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca{sup 2+}. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO{sub 3} (101{sup ¯}4)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for {sup 43}Ca, {sup 13}C, and {sup 17}O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.

  13. Recent Advances in Characterization of Lignin Polymer by Solution-State Nuclear Magnetic Resonance (NMR Methodology

    Directory of Open Access Journals (Sweden)

    Run-Cang Sun

    2013-01-01

    Full Text Available The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery. Traditionally, it has been attempted to reveal the complicated and heterogeneous structure of lignin by a series of chemical analyses, such as thioacidolysis (TA, nitrobenzene oxidation (NBO, and derivatization followed by reductive cleavage (DFRC. Recent advances in nuclear magnetic resonance (NMR technology undoubtedly have made solution-state NMR become the most widely used technique in structural characterization of lignin due to its versatility in illustrating structural features and structural transformations of lignin polymers. As one of the most promising diagnostic tools, NMR provides unambiguous evidence for specific structures as well as quantitative structural information. The recent advances in two-dimensional solution-state NMR techniques for structural analysis of lignin in isolated and whole cell wall states (in situ, as well as their applications are reviewed.

  14. MRI and unilateral NMR study of reindeer skin tanning processes.

    Science.gov (United States)

    Zhu, Lizheng; Del Federico, Eleonora; Ilott, Andrew J; Klokkernes, Torunn; Kehlet, Cindie; Jerschow, Alexej

    2015-04-07

    The study of arctic or subarctic indigenous skin clothing material, known for its design and ability to keep the body warm, provides information about the tanning materials and techniques. The study also provides clues about the culture that created it, since tanning processes are often specific to certain indigenous groups. Untreated skin samples and samples treated with willow (Salix sp) bark extract and cod liver oil are compared in this study using both MRI and unilateral NMR techniques. The two types of samples show different proton spatial distributions and different relaxation times, which may also provide information about the tanning technique and aging behavior.

  15. Solid-state {sup 2}H NMR investigations in guest-host systems and plastic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Garibay, J.A.V.

    2004-07-01

    Variable temperature {sup 2}H NMR investigations have been carried out to study the molecular behavior of perdeuterated benzene and pyridine in the inclusion compound with tris-(1,2-dioxyphenyl)-cyclotriphosphazene. Here, a comprehensive variable temperature {sup 2}H NMR study is presented comprising line shape studies and relaxation experiments. The experimental data clearly indicate the presence of highly mobile guest species. Sample cooling gives rise to characteristic line shape effects that can be attributed to a slow-down of the rotational motion. Additional {sup 2}H NMR measurements were performed on the plastic crystal 1,4-diazabicyclo[2,2,2]octane where highly mobile species were observed. A quantitative analysis of the experimental data is achieved by appropriate computer simulations taking into account various molecular motions for each studied system. The analysis of these theoretical data give rise to the kinetic parameters that are in the order of related systems. (orig.)

  16. Genotype evaluation of cowpea seeds (Vigna unguiculata) using 1H qNMR combined with exploratory tools and solid-state NMR.

    Science.gov (United States)

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

    2017-01-01

    The ultimate aim of this study was to apply a non-targeted chemometric analysis (principal component analysis and hierarchical clustering analysis using the heat map approach) of NMR data to investigate the variability of organic compounds in nine genotype cowpea seeds, without any complex pre-treatment. In general, both exploratory tools show that Tvu 233, CE-584, and Setentão genotypes presented higher amount mainly of raffinose and Tvu 382 presented the highest content of choline and least content of raffinose. The evaluation of the aromatic region showed the Setentão genotype with highest content of niacin/vitamin B3 whereas Tvu 382 with lowest amount. To investigate rigid and mobile components in the seeds cotyledon, 13 C CP and SP/MAS solid-state NMR experiments were performed. The cotyledon of the cowpea comprised a rigid part consisting of starch as well as a soft portion made of starch, fatty acids, and protein. The variable contact time experiment suggests the presence of lipid-amylose complexes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state {sup 13}C NMR and solution {sup 31}P NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shasha [College of Water Sciences, Beijing Normal University, Beijing 100875 (China); State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Zhu, Yuanrong, E-mail: zhuyuanrong07@mails.ucas.ac.cn [State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Meng, Wei, E-mail: mengwei@craes.org.cn [State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); He, Zhongqi [USDA-ARS Southern Regional Research Center, 1100 Robert E Lee Blvd, New Orleans, LA 70124 (United States); Feng, Weiying [College of Water Sciences, Beijing Normal University, Beijing 100875 (China); State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Zhang, Chen [State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Giesy, John P. [State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Department of Biomedical and Veterinary Biosciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan (Canada)

    2016-02-01

    Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state {sup 13}C NMR and solution {sup 31}P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O–C–O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH{sub 3} and COO/N–C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH{sub 3} and COO/N–C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes. - Highlights: • WEOM derived from aquatic macrophytes was characterized. • C and P in WEOM were characterized by solid {sup 13}C NMR and solution {sup 31}P NMR. • Degradation and transformation of macrophyte-derived C and P were investigated. • Macrophyte-derived WEOM are important source for bioavailable nutrients in lakes.

  18. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

    Science.gov (United States)

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

  19. NMR studies of phase behaviour in polyacrylonitrile solutions

    International Nuclear Information System (INIS)

    Golightly, J.A.

    1998-10-01

    The aim of the thesis was to study the phase behaviour of aqueous polyacrylonitrile/NaSCN solutions using a variety of nuclear magnetic resonance techniques. Polyacrylonitrile (PAN) is the basis of the acrylic fibre industry, as such fibres contain at least 85% PAN. Despite this industrial importance, the available literature describing the phase behaviour of PAN in solution is far from comprehensive. Bulk 1 H NMR relaxation measurements were carried out over a wide range of concentrations and temperatures to probe the molecular dynamics of the PAN and water molecules. The relaxation data was found to be biexponential decay for all samples, the relative amplitudes of which were shown to be equal to the ratio of PAN protons to water protons. Both species were found to be in the regime of rapid molecular motion. Bulk 1 H NMR self diffusion measurements, using the PFGSTE technique, exhibited a bi-exponential decay of the echo amplitudes. By careful selection of the observation time, Δ, it was possible to independently probe the water and PAN translational diffusion. A background gradient, resulting from inhomogeneities of the magnetic field, complicated the analysis of the data and a novel polynomial least squares fitting procedure was devised to overcome this effect. The measured attenuation of the water diffusion coefficients (D∼10 -6 -10 -5 cm 2 s -1 ) with increasing PAN volume fraction was modelled according to various theories, including free volume and scaling laws. The study of the PAN diffusion coefficient (D∼10 -7 -10 -6 cm 2 s -1 ) was limited by the experimental constraints of the NMR spectrometer. A 1 H NMR one-dimensional imaging technique was used to study the non-solvent induced phase separation (coagulation) of a PAN solution. The time dependence of the measured profiles allowed observation of the coagulation process. A diffusion model was developed to fit the experimental data using a semi-infinite diffusion framework. The fitting parameters

  20. Structural diversity of solid dispersions of acetylsalicylic acid as seen by solid-state NMR.

    Science.gov (United States)

    Policianova, Olivia; Brus, Jiri; Hruby, Martin; Urbanova, Martina; Zhigunov, Alexander; Kredatusova, Jana; Kobera, Libor

    2014-02-03

    Solid dispersions of active pharmaceutical ingredients are of increasing interest due to their versatile use. In the present study polyvinylpyrrolidone (PVP), poly[N-(2-hydroxypropyl)-metacrylamide] (pHPMA), poly(2-ethyl-2-oxazoline) (PEOx), and polyethylene glycol (PEG), each in three Mw, were used to demonstrate structural diversity of solid dispersions. Acetylsalicylic acid (ASA) was used as a model drug. Four distinct types of the solid dispersions of ASA were created using a freeze-drying method: (i) crystalline solid dispersions containing nanocrystalline ASA in a crystalline PEG matrix; (ii) amorphous glass suspensions with large ASA crystallites embedded in amorphous pHPMA; (iii) solid solutions with molecularly dispersed ASA in rigid amorphous PVP; and (iv) nanoheterogeneous solid solutions/suspensions containing nanosized ASA clusters dispersed in a semiflexible matrix of PEOx. The obtained structural data confirmed that the type of solid dispersion can be primarily controlled by the chemical constitutions of the applied polymers, while the molecular weight of the polymers had no detectable impact. The molecular structure of the prepared dispersions was characterized using solid-state NMR, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). By applying various (1)H-(13)C and (1)H-(1)H correlation experiments combined with T1((1)H) and T1ρ((1)H) relaxation data, the extent of the molecular mixing was determined over a wide range of distances, from intimate intermolecular contacts (0.1-0.5 nm) up to the phase-separated nanodomains reaching ca. 500 nm. Hydrogen-bond interactions between ASA and polymers were probed by the analysis of (13)C and (15)N CP/MAS NMR spectra combined with the measurements of (1)H-(15)N dipolar profiles. Overall potentialities and limitations of individual experimental techniques were thoroughly evaluated.

  1. NMR study of CeCoSi3

    International Nuclear Information System (INIS)

    Iwamoto, Y.

    1995-01-01

    Low-temperature susceptibility, NMR and NQR of the 59 Co signal in CeCoSi 3 have been measured. CeCoSi 3 showed a superconducting transition at 0.7-1.2K. From NQR measurement, the nuclear quadrupole frequency and the full width at half maximum (FWHM) of 59 Co in CeCoSi 3 were estimated to be about 1.08MHz and 0.08MHz, respectively. The 59 Co nuclear spin-lattice relaxation rate (1/T 1 ) in CeCoSi 3 was proportional to the temperature (T) as the Fermi liquid state above the superconducting transition temperature (T c ), and then rapidly decreased below T c . ((orig.))

  2. 1H NMR studies of human lysozyme: Spectral assignment and comparison with hen lysozyme

    International Nuclear Information System (INIS)

    Redfield, C.; Dobson, C.M.

    1990-01-01

    Complete main-chain (NH and αCH) 1 H NMR assignments are reported for the 130 residues of human lysozyme, along with extensive assignments for side-chain protons. Analysis of 2-D NOESY experiments shows that the regions of secondary structure for human lysozyme in solution are essentially identical with those found previously in a similar study of hen lysozyme and are in close accord with the structure of the protein reported previously from x-ray diffraction studies in the crystalline state. Comparison of the chemical shifts, spin-spin coupling constants, and hydrogen exchange behavior are also consistent with closely similar structures for the two proteins in solution. In a number of cases specific differences in the NMR parameters between hen and human lysozymes can be correlated with specific differences observed in the crystal structures

  3. Solid-state 13C NMR characterization of polyanilines

    International Nuclear Information System (INIS)

    Kaplan, S.

    1988-01-01

    13 C solid-state nuclear magnetic resonance measurements are reported for the leucoemeraldine base, emeraldine base, and emeraldine hydrochloride forms of polyaniline in order to characterize the structures of these three distinct polymers. Chemical shift assignments are facilitated by use of the cross-depolarization technique to distinguish carbons with and without directly bonded hydrogens. Comparison of the spectra of emeraldine base with those of leucoemeraldine base and air-oxidized leucoemeraldine (which partially converts to emeraldine base) establishes that emeraldine base is essentially an alternating copolymer of reduced 1A (-(C 6 H 4 )N(H)(C 6 H 4 )N(H)-) and oxidized 2A (-(C 6 H 4 )N double-bond(C 6 H 4 )double-bond N-) repeat units. The 8-12 ppm spectral line widths measured for both emeraldine base and leucoemeraldine base are attributed to local fluctuations in conformational and configurational geometries, a distribution in chain packing, and compositional defects. 13 C spin-echo measurements establish that the 60 ppM wide line from the conducting emeraldine hydrochloride is inhomogeneously broadened. It is postulated that this line width is due to local variations in charge density along the polymer backbone arising from polymer structural heterogeneity. 47 refs., 5 figs., 1 tab

  4. Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Elena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Gath, Julia [ETH Zurich, Physical Chemistry (Switzerland); Habenstein, Birgit [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Ravotti, Francesco; Szekely, Kathrin; Huber, Matthias [ETH Zurich, Physical Chemistry (Switzerland); Buchner, Lena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Boeckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Guentert, Peter, E-mail: guentert@em.uni-frankfurt.de [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany)

    2013-07-15

    Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218-289) and {alpha}-synuclein yielded 88-97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77-90 % correctness if also assignments classified as tentative by the algorithm are included.

  5. Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

    International Nuclear Information System (INIS)

    Schmidt, Elena; Gath, Julia; Habenstein, Birgit; Ravotti, Francesco; Székely, Kathrin; Huber, Matthias; Buchner, Lena; Böckmann, Anja; Meier, Beat H.; Güntert, Peter

    2013-01-01

    Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218–289) and α-synuclein yielded 88–97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77–90 % correctness if also assignments classified as tentative by the algorithm are included

  6. Non-Bloch decay of Rabi oscillations in liquid state NMR

    Science.gov (United States)

    Chakrabarti, Arnab; Bhattacharyya, Rangeet

    2018-03-01

    Rabi oscillations are known to exhibit non-Bloch behaviour in anisotropic media. In this letter, we report an experimental observation of non-Bloch decay of Rabi oscillations in isotropic liquid state NMR. To avoid the dephasing due to the radio-frequency inhomogeneities, we develop a modified version of the rotary echo protocol and use it to determine the decay rates of Rabi oscillations. We find that the measured decay rates are proportional to the square of the Rabi frequencies and the proportionality constant is of the order of tens of picoseconds. Further, we show that this non-Bloch nature of the decay rates becomes less prominent with increasing temperature. The implications of the presence of non-Bloch decay rates in liquid state NMR in the context of ensemble quantum computing are also discussed.

  7. 13C CPMAS NMR Studies of Anthocyanidins and their Glucosides

    International Nuclear Information System (INIS)

    Wolniak, M.; Wawer, I.

    2005-01-01

    Anthocyanins are responsible for red, purple or blue colours of flower petals and can be found in red or black fruits and berries. Many foods, especially red grapes and wines, aronia or blueberries contain large amounts of anthocyanins. Their health beneficial effects are related to antioxidant and radical scavenging properties. Structural analysis of anthocyanins by NMR are few, owing to the difficulty in obtaining analysable spectra for unstable, interconverting compounds, available in small amounts. Compounds studied by us were isolated from fruits and berries. 13 C CPMAS NMR spectra were recorded on a Bruker DSX-400 spectrometer for solid chlorides of: cyanidin, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, pelargonidin and pelargonidin 3-O-glucoside. Dipolar dephased and short contact pulse sequences were used as an aid in the assignment of resonances in CPMAS spectra of solids. Inspection of the spectra indicates that anthocyanidins are in the form of flavylium (cationic) and not in form of the chalcone.: the resonance of C2 appears at ca. 160 ppm and C3 at ca. 135 ppm, whereas C ring opening produces C2 = O, for which chemical shift of ca. 180 ppm can be expected. A comparison of experimental (CPMAS) and predicted (GIAO DFT) shielding constants for cyanidin provided information about the orientation of OH groups, twist angle of aromatic ring B and the localization of the chloride anion.(author)

  8. LARGE SCALE PRODUCTION, PURIFICATION, AND 65CU SOLID STATE NMR OF AZURIN

    Energy Technology Data Exchange (ETDEWEB)

    Gao, A.; Heck, R.W.

    2008-01-01

    This paper details a way to produce azurin with an effi ciency over 10 times greater than previously described and demonstrates the fi rst solid state nuclear magnetic resonance spectrum of 65Cu(I) in a metalloprotein. A synthetic gene for azurin based upon the DNA sequence from Pseudomonas aeruginosa including the periplasmic targeting sequence was subcloned into a T7 overexpression vector to create the plasmid pGS-azurin, which was transformed into BL21 (DE3) competent cells. The leader sequence on the expressed protein causes it to be exported to the periplasmic space of Escherichia coli. Bacteria grown in a fermentation unit were induced to overexpress the azurin, which was subsequently purifi ed through an endosmotic shock procedure followed by high performance liquid chromatography (HPLC). 1,500 mg of azurin were purifi ed per liter of culture. 65Cu(II) was added to apo-azurin and then reduced. The 65Cu metal cofactor in azurin was observed with solid state nuclear magnetic resonance (NMR) to determine any structural variations that accompanied copper reduction. This is the fi rst solid state NMR spectra of a copper(I) metalloprotein. Analysis of the NMR spectra is being used to complement hypotheses set forth by x-ray diffraction and computational calculations of electron transfer mechanisms in azurin.

  9. Visualising substrate-fingermark interactions: Solid-state NMR spectroscopy of amino acid reagent development on cellulose substrates.

    Science.gov (United States)

    Spindler, Xanthe; Shimmon, Ronald; Roux, Claude; Lennard, Chris

    2015-05-01

    Most spectroscopic studies of the reaction products formed by ninhydrin, 1,2-indanedione-zinc (Ind-Zn) and 1,8-diazafluoren-9-one (DFO) when reacted with amino acids or latent fingermarks on paper substrates are focused on visible absorption or luminescence spectroscopy. In addition, structural elucidation studies are typically limited to solution-based mass spectrometry or liquid nuclear magnetic resonance (NMR) spectroscopy, which does not provide an accurate representation of the fingermark development process on common paper substrates. The research presented in this article demonstrates that solid-state carbon-13 magic angle spinning NMR ((13)C-MAS-NMR) is a technique that can not only be utilised for structural studies of fingermark enhancement reagents, but is a promising technique for characterising the effect of paper chemistry on fingermark deposition and enhancement. The latter opens up a research area that has been under-explored to date but has the potential to improve our understanding of how fingermark secretions and enhancement reagents interact with paper substrates. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. High resolution solid-state NMR spectroscopy of the Yersinia pestis outer membrane protein Ail in lipid membranes

    International Nuclear Information System (INIS)

    Yao, Yong; Dutta, Samit Kumar; Park, Sang Ho; Rai, Ratan; Fujimoto, L. Miya; Bobkov, Andrey A.; Opella, Stanley J.; Marassi, Francesca M.

    2017-01-01

    The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail’s biological activity. Here, we demonstrate that high-resolution solid-state NMR spectra can be obtained from samples of Ail in detergent-free phospholipid liposomes, prepared with a lipid to protein molar ratio of 100. The spectra, obtained with 13 C or 1 H detection, have very narrow line widths (0.40–0.60 ppm for 13 C, 0.11–0.15 ppm for 1 H, and 0.46–0.64 ppm for 15 N) that are consistent with a high level of sample homogeneity. The spectra enable resonance assignments to be obtained for N, CO, CA and CB atomic sites from 75 out of 156 residues in the sequence of Ail, including 80% of the transmembrane region. The 1 H-detected solid-state NMR 1 H/ 15 N correlation spectra obtained for Ail in liposomes compare very favorably with the solution NMR 1 H/ 15 N TROSY spectra obtained for Ail in nanodiscs prepared with a similar lipid to protein molar ratio. These results set the stage for studies of the molecular basis of the functional interactions of Ail with its protein partners from human host cells, as well as the development of drugs targeting Ail.

  11. High resolution solid-state NMR spectroscopy of the Yersinia pestis outer membrane protein Ail in lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yong; Dutta, Samit Kumar [Sanford Burnham Prebys Medical Discovery Institute (United States); Park, Sang Ho; Rai, Ratan [University of California San Diego, Department of Chemistry and Biochemistry (United States); Fujimoto, L. Miya; Bobkov, Andrey A. [Sanford Burnham Prebys Medical Discovery Institute (United States); Opella, Stanley J. [University of California San Diego, Department of Chemistry and Biochemistry (United States); Marassi, Francesca M., E-mail: fmarassi@sbp.edu [Sanford Burnham Prebys Medical Discovery Institute (United States)

    2017-03-15

    The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail’s biological activity. Here, we demonstrate that high-resolution solid-state NMR spectra can be obtained from samples of Ail in detergent-free phospholipid liposomes, prepared with a lipid to protein molar ratio of 100. The spectra, obtained with {sup 13}C or {sup 1}H detection, have very narrow line widths (0.40–0.60 ppm for {sup 13}C, 0.11–0.15 ppm for {sup 1}H, and 0.46–0.64 ppm for {sup 15}N) that are consistent with a high level of sample homogeneity. The spectra enable resonance assignments to be obtained for N, CO, CA and CB atomic sites from 75 out of 156 residues in the sequence of Ail, including 80% of the transmembrane region. The {sup 1}H-detected solid-state NMR {sup 1}H/{sup 15}N correlation spectra obtained for Ail in liposomes compare very favorably with the solution NMR {sup 1}H/{sup 15}N TROSY spectra obtained for Ail in nanodiscs prepared with a similar lipid to protein molar ratio. These results set the stage for studies of the molecular basis of the functional interactions of Ail with its protein partners from human host cells, as well as the development of drugs targeting Ail.

  12. Unconventional superconductivity in PuRhGa5: Ga NMR/NQR study

    International Nuclear Information System (INIS)

    Sakai, H.; Tokunaga, Y.; Fujimoto, T.; Kambe, S.; Walstedt, R.E.; Yasuoka, H.; Aoki, D.; Homma, Y.; Yamamoto, E.; Nakamura, A.; Shiokawa, Y.; Nakajima, K.; Arai, Y.; Matsuda, T.D.; Haga, Y.; Onuki, Y.

    2006-01-01

    69,71 Ga NMR/NQR studies have been performed on a single crystal of the transuranium superconductor PuRhGa 5 with T c ∼9K. The spin-lattice relaxation rate 1/T 1 reveals that PuRhGa 5 is an unconventional superconductor having an anisotropic superconducting gap. Moreover, Korringa behavior (1/T 1 T=const.) is observed in the normal state below ∼30K. This result suggests that the superconductivity sets in after the formation of a Fermi liquid state in this compound

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

    International Nuclear Information System (INIS)

    Marion, D.

    2008-07-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  15. Solution NMR study of the yeast cytochrome c peroxidase: cytochrome c interaction

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, Alexander N., E-mail: ovolkov@vub.ac.be; Nuland, Nico A. J. van [Vrije Universiteit Brussel, Jean Jeener NMR Centre, Structural Biology Brussels (Belgium)

    2013-07-15

    Here we present a solution NMR study of the complex between yeast cytochrome c (Cc) and cytochrome c peroxidase (CcP), a paradigm for understanding the biological electron transfer. Performed for the first time, the CcP-observed heteronuclear NMR experiments were used to probe the Cc binding in solution. Combining the Cc- and CcP-detected experiments, the binding interface on both proteins was mapped out, confirming that the X-ray structure of the complex is maintained in solution. Using NMR titrations and chemical shift perturbation analysis, we show that the interaction is independent of the CcP spin-state and is only weakly affected by the Cc redox state. Based on these findings, we argue that the complex of the ferrous Cc and the cyanide-bound CcP is a good mimic of the catalytically-active Cc-CcP compound I species. Finally, no chemical shift perturbations due to the Cc binding at the low-affinity CcP site were observed at low ionic strength. We discuss possible reasons for the absence of the effects and outline future research directions.

  16. Development and Application of a Low-Volume Flow System for Solution-State in Vivo NMR.

    Science.gov (United States)

    Tabatabaei Anaraki, Maryam; Dutta Majumdar, Rudraksha; Wagner, Nicole; Soong, Ronald; Kovacevic, Vera; Reiner, Eric J; Bhavsar, Satyendra P; Ortiz Almirall, Xavier; Lane, Daniel; Simpson, Myrna J; Heumann, Hermann; Schmidt, Sebastian; Simpson, André J

    2018-06-18

    In vivo nuclear magnetic resonance (NMR) spectroscopy is a particularly powerful technique, since it allows samples to be analyzed in their natural, unaltered state, criteria paramount for living organisms. In this study, a novel continuous low-volume flow system, suitable for in vivo NMR metabolomics studies, is demonstrated. The system allows improved locking, shimming, and water suppression, as well as allowing the use of trace amounts of expensive toxic contaminants or low volumes of precious natural environmental samples as stressors. The use of a double pump design with a sump slurry pump return allows algal food suspensions to be continually supplied without the need for filters, eliminating the possibility of clogging and leaks. Using the flow system, the living organism can be kept alive without stress indefinitely. To evaluate the feasibility and applicability of the flow system, changes in the metabolite profile of 13 C enriched Daphnia magna over a 24-h period are compared when feeding laboratory food vs exposing them to a natural algal bloom sample. Clear metabolic changes are observed over a range of metabolites including carbohydrates, lipids, amino acids, and a nucleotide demonstrating in vivo NMR as a powerful tool to monitor environmental stress. The particular bloom used here was low in microcystins, and the metabolic stress impacts are consistent with the bloom being a poor food source forcing the Daphnia to utilize their own energy reserves.

  17. NMR study of thermal decomposition of lithium tetrahydroaluminate

    International Nuclear Information System (INIS)

    Tarasov, V.P.; Bakum, S.I.; Kuznetsova, S.F.

    1997-01-01

    Pyrolysis of lithium aluminotetrahydrides and deuterides, LiAlH 4 and LiAlD 4 , was studied by 1 H, 7 Li, 27 Al NMR in 20-700 deg C range. 20-30 time constriction of resonance lines of studied nuclei at 170 deg C testifies to melting of the compounds. It is shown that at LiAlD 4 melting point the first stage of pyrolysis is described by two parallel reactions: LiAlD 4 -> LiD + Al + D 2 , LiAlD 4 + LiD -> Li 3 AlD 6 , which proceed with different rates. It was revealed that reactions of lithium hydride (deuteride) with metallic aluminium at temperatures above 400 deg C resulted to formation of intermetallic compounds of LiAl and LiAl 3 composition. LiAl is characterized by higher thermal stability, than LiAl 3 . 20 refs., 6 figs., 2 tabs

  18. NMR studies of two spliced leader RNAs using isotope labeling

    Energy Technology Data Exchange (ETDEWEB)

    Lapham, J.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

    1994-12-01

    Spliced leader RNAs are a class of RNA molecules (<200 nts) involved in the trans splicing of messenger RNA found in trypanosomes, nematodes, and other lower eukaryotes. The spliced leader RNA from the trypanosome Leptomonas Collosoma exists in two alternate structural forms with similar thermal stabilities. The 54 nucleotides on the 5{prime} end of the SL molecule is structurally independent from the 3{prime} half of the RNA, and displays the two structural forms. Furthermore, the favored of the two structures was shown to contain anomalous nuclease sensitivity and thermal stability features, which suggests that there may be tertiary interactions between the splice site and other nucleotides in the 5{prime} end. Multidimensional NMR studies are underway to elucidate the structural elements present in the SL RNAs that give rise to their physical properties. Two spliced leader sequences have been studied. The first, the 54 nucleotides on the 5{prime} end of the L. Collosoma sequence, was selected because of earlier studies in our laboratory. The second sequence is the 5{prime} end of the trypanosome Crithidia Fasciculata, which was chosen because of its greater sequence homology to other SL sequences. Given the complexity of the NMR spectra for RNA molecules of this size, we have incorporated {sup 15}N/{sup 13}C-labeled nucleotides into the RNA. One of the techniques we have developed to simplify the spectra of these RNA molecules is isotope labeling of specific regions of the RNA. This has been especially helpful in assigning the secondary structure of molecules that may be able to adopt multiple conformations. Using this technique one can examine a part of the molecule without spectral interference from the unlabeled portion. We hope this approach will promote an avenue for studying the structure of larger RNAs in their native surroundings.

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

    Science.gov (United States)

    Chong, Yuan

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

  20. Overcoming the solubility limit with solubility-enhancement tags: successful applications in biomolecular NMR studies

    International Nuclear Information System (INIS)

    Zhou Pei; Wagner, Gerhard

    2010-01-01

    Although the rapid progress of NMR technology has significantly expanded the range of NMR-trackable systems, preparation of NMR-suitable samples that are highly soluble and stable remains a bottleneck for studies of many biological systems. The application of solubility-enhancement tags (SETs) has been highly effective in overcoming solubility and sample stability issues and has enabled structural studies of important biological systems previously deemed unapproachable by solution NMR techniques. In this review, we provide a brief survey of the development and successful applications of the SET strategy in biomolecular NMR. We also comment on the criteria for choosing optimal SETs, such as for differently charged target proteins, and recent new developments on NMR-invisible SETs.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  2. SIMPSON: A general simulation program for solid-state NMR spectroscopy

    Science.gov (United States)

    Bak, Mads; Rasmussen, Jimmy T.; Nielsen, Niels Chr.

    2011-12-01

    A computer program for fast and accurate numerical simulation of solid-state NMR experiments is described. The program is designed to emulate a NMR spectrometer by letting the user specify high-level NMR concepts such as spin systems, nuclear spin interactions, RF irradiation, free precession, phase cycling, coherence-order filtering, and implicit/explicit acquisition. These elements are implemented using the Tel scripting language to ensure a minimum of programming overhead and direct interpretation without the need for compilation, while maintaining the flexibility of a full-featured programming language. Basicly, there are no intrinsic limitations to the number of spins, types of interactions, sample conditions (static or spinning, powders, uniaxially oriented molecules, single crystals, or solutions), and the complexity or number of spectral dimensions for the pulse sequence. The applicability ranges from simple ID experiments to advanced multiple-pulse and multiple-dimensional experiments, series of simulations, parameter scans, complex data manipulation/visualization, and iterative fitting of simulated to experimental spectra. A major effort has been devoted to optimizing the computation speed using state-of-the-art algorithms for the time-consuming parts of the calculations implemented in the core of the program using the C programming language. Modification and maintenance of the program are facilitated by releasing the program as open source software (General Public License) currently at http://nmr.imsb.au.dk. The general features of the program are demonstrated by numerical simulations of various aspects for REDOR, rotational resonance, DRAMA, DRAWS, HORROR, C7, TEDOR, POST-C7, CW decoupling, TPPM, F-SLG, SLF, SEMA-CP, PISEMA, RFDR, QCPMG-MAS, and MQ-MAS experiments.

  3. Part I. Generation of tailored radio-frequency pulses for NMR. Part II. Deuterium NMR studies of oriented DNA, and its interaction with water

    International Nuclear Information System (INIS)

    Brandes, R.

    1988-01-01

    A novel method for generating tailored radio-frequency pulses for use in NMR is presented. For this purpose, an inexpensive device based on analog audio filters was built. As an application, the superior selectivity of this method is shown by comparing it with a soft pulse excitation. The theoretical response of the magnetization to these tailored rf pulses is also calculated. Deuterium NMR line shapes of 2 H-labeled purine bases in solid, uniaxially oriented Li- and Na-DNA have been obtained. The spectral densities of motion were determined for the Li-DNA samples to test a model for uncorrelated, restricted base motion. For the first time, a 2 H spectrum is reported for 2 H labeled DNA in the liquid crystalline state. A procedure is outlined to separate the base motion from the DNA axis motion. In addition to the studies of DNA itself, the interaction of water (D 2 O) with samples of uniaxially oriented Na- and Li-DNA have been studied by high resolution 2 H NMR

  4. TD-NMR studies on CuSO{sub 4} salt hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Nestle, Nikolaus; Magin, Peter; Wengeler, Robert [BASF Aktiengesellschaft, Ludwigshafen (Germany); Kleinschmidt, Sebastian [Universitaet Magdeburg, FB Chemie (Germany)

    2008-07-01

    Despite the high concentration of paramagnetic copper ions, solid CuSO{sub 4} hydrates exhibit surprizingly narrow NMR signals. This is known since the late 1940s. Using TD-NMR methods established for polymer studies, the relaxation behaviour of CuSO{sub 4} preparations with different water content was studied at room temperature. For the water content of the pentahydrate and below, the NMR signal exhibits a pure solid-state-type magnetization decay behaviour. For slightly overstoichiometric moisture contents, a liquid-like signal is observed in addition to the solid signal. However, the relative amplitudes of the solid and the liquid signal do not mirror the stoichiometric composition of the pentahydrate and the excess water. Instead, the solid signal amplitude only accounts for four hydrate water molecules while the fifth water exhibits rapid exchange with the liquid phase and thus contributes to the liquid-type signal. This finding is in good agreement to results from investigations into the crystal structure of solid CuSO4 pentahydrate.

  5. NMR studies of interfaces, strain and anisotropy in Co/Cu multilayers

    International Nuclear Information System (INIS)

    Thomson, T.; Riedi, P.C.

    1999-01-01

    59 Co NMR studies of multilayers are able to give three direct pieces of information: (i) the crystal phase of Co, fcc (217.4 MHz), hcp (220-228 MHz) and in exotic cases bcc (198 MHz) for films measured at T= 4.2 K, (ii) the nature of the interfaces from low frequency satellite lines, and (iii) the strain state deduced from small changes in the line positions. Extensive studies of Co/Cu multilayer interfacial structures as a function of deposition technique, layer thickness, substrate/buffer layer structure and annealing temperature have been undertaken. This work has shed new light on the relationship between interfacial structure and magnetoresistance and in particular has demonstrated that flat, atomic scale, interfaces lead to greater magnetoresistance. The difference between the Co and Cu lattice constant results in an extensive, tensile in-plane strain developing in Co layers provided that some epitaxial registry is present. Information on strain effects can be obtained from the position and width of the NMR lines. The magnetic anisotropy field can be determined by measuring the field dependence of the enhancement effect due to electronic magnetisation. This provides unique insight into the distribution of magnetic anisotropy within the Co layers, as the enhancement can be investigated independently for each NMR line and, hence, provides environment specific information on magnetic anisotropy at the interfaces and in the interior of the layers

  6. Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet.

    Science.gov (United States)

    Vennemann, T; Jeong, M; Yoon, D; Magrez, A; Berger, H; Yang, L; Živković, I; Babkevich, P; Rønnow, H M

    2018-04-01

    We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO 4 with S = 1/2 (Mo 5+ ) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31 P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

  7. Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet

    Science.gov (United States)

    Vennemann, T.; Jeong, M.; Yoon, D.; Magrez, A.; Berger, H.; Yang, L.; Živković, I.; Babkevich, P.; Rønnow, H. M.

    2018-04-01

    We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO4 with S = 1/2 (Mo5+) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

  8. Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state (13)C NMR and solution (31)P NMR spectroscopy.

    Science.gov (United States)

    Liu, Shasha; Zhu, Yuanrong; Meng, Wei; He, Zhongqi; Feng, Weiying; Zhang, Chen; Giesy, John P

    2016-02-01

    Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state (13)C NMR and solution (31)P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O-C-O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH3 and COO/N-C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH3 and COO/N-C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state 13C NMR and solution 31P NMR spectroscopy

    Science.gov (United States)

    LIU, S. S.; Zhu, Y.; Meng, W.; Wu, F.

    2016-12-01

    Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state 13C NMR and solution 31P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O-C-O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH3 and COO/N-C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH3 and COO/N-C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes.

  10. High resolution NMR spectroscopy of synthetic polymers in bulk

    International Nuclear Information System (INIS)

    Komorski, R.A.

    1986-01-01

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

  11. Changes in Lignin and Polysaccharide Components in 13 Cultivars of Rice Straw following Dilute Acid Pretreatment as Studied by Solution-State 2D 1H-13C NMR

    Science.gov (United States)

    Teramura, Hiroshi; Sasaki, Kengo; Oshima, Tomoko; Aikawa, Shimpei; Matsuda, Fumio; Okamoto, Mami; Shirai, Tomokazu; Kawaguchi, Hideo; Ogino, Chiaki; Yamasaki, Masanori; Kikuchi, Jun; Kondo, Akihiko

    2015-01-01

    A renewable raw material, rice straw is pretreated for biorefinery usage. Solution-state two-dimensional (2D) 1H-13 C hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, was used to analyze 13 cultivars of rice straw before and after dilute acid pretreatment, to characterize general changes in the lignin and polysaccharide components. Intensities of most (15 of 16) peaks related to lignin aromatic regions, such as p-coumarate, guaiacyl, syringyl, p-hydroxyphenyl, and cinnamyl alcohol, and methoxyl, increased or remained unchanged after pretreatment. In contrast, intensities of most (11 of 13) peaks related to lignin aliphatic linkages or ferulate decreased. Decreased heterogeneity in the intensities of three peaks related to cellulose components in acid-insoluble residues resulted in similar glucose yield (0.45–0.59 g/g-dry biomass). Starch-derived components showed positive correlations (r = 0.71 to 0.96) with glucose, 5-hydroxymethylfurfural (5-HMF), and formate concentrations in the liquid hydrolysates, and negative correlations (r = –0.95 to –0.97) with xylose concentration and acid-insoluble residue yield. These results showed the fate of lignin and polysaccharide components by pretreatment, suggesting that lignin aromatic regions and cellulose components were retained in the acid insoluble residues and starch-derived components were transformed into glucose, 5-HMF, and formate in the liquid hydrolysate. PMID:26083431

  12. Positively charged polysilsesquioxane/iodide lonic liquid as a quasi solid-state redox electrolyte for dye-sensitized photo electrochemical cells: infrared, 29 Si NMR, and electrical studies

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available A new sol-gel precursor based on 1-methyl-3-[3-(trimethoxy- λ 4 -silylpropyl]-1 H -imidazolium iodide (MTMSPI + I − was synthesized and investigated as a potential novel quasi solid-state ionic liquid redox electrolyte for dye-synthesized photoelectrochemical (DSPEC cells of the Graetzel type. MTMSPI + I − was hydrolyzed with acidified water and the reaction products of the sol-gel condensation reactions assessed with the help of 29 Si NMR and infrared spectroscopic techniques. Results of the time-dependent spectra analyses showed the formation of positively charged polyhedral cube-like silsesquioxane species that still contained a small amount of silanol end groups, which were removed after heating at 200 ° C . After cooling, the resulting material formed is a tough, yellowish, and transparent solid, which could be reheated again and used for assembling DSPEC cells. The addition of iodine increased the specific conductivity of the hydrolyzed and nonhydrolyzed MTMSPI + I − , which we attributed to the formation of triiodide ions contributed to the conductivity via the Grotthus mechanism. DSPEC cells based on a titania-dye system with MTMSPI + I − electrolyte containing iodine (0.1 M reached an overall efficiency between 3.3–3.7%.

  13. The bonded in the chestnut-tree (Aesculus hippocastanum L.) bark water freezing process studied by means NMR method

    International Nuclear Information System (INIS)

    Haranczyk, H.; Weglarz, W.

    1994-01-01

    The bonded in the chestnut-tree (Aesculus hippocastanum L.) bark water freezing process was studied by means NMR method. The measured relaxation time (as a function of temperature) shows two compounds. First from solid state water (T 2 * 20 μs) and the second one from liquid water (T 2 * = 1 ms). This results are presented and discussed

  14. Interaction of charged amphiphilic drugs with phosphatidylcholine vesicles studied by NMR

    International Nuclear Information System (INIS)

    Eriksson, L.E.G.

    1987-01-01

    Small unilamellar vesicles from egg phosphatidylcholine in NaCl solutions were exposed to some amphiphilic pharmaca. The aromatic drugs (chlorpromazine, dibucaine, tetracaine, imipramine and propranolol) were in their cationic form of the amines. By 1 H- and 31 P-NMR the membrane signals were observed. In particular, the N-methyl choline proton signals were followed upon drug addition. The intrinsic chemical shift difference (0.02 ppm) between the inner (upfield) and outer choline signals was influenced by the drug concentration. Packing properties of the lipid head groups and ring current shift probably contributed. At very high drug concentration, the vesicles are destroyed. A transformation into a micellar state with a high sample viscosity took place in a narrow concentration range of drug. The anion effects of Cl - were studied from the 35 Cl-NMR linewidth at 9.8 and 39.1 MHz. A continuous increase in the signal linewidth followed upon drug addition to the vesicles. Only chlorpromazine produced a broadening in the absence of vesicles (NaCl blank). The linewidth reflected a critical micelle concentration of this drug around 7 mM in 0.1 M NaCl. The 35 Cl-NMR experiments demonstrated the existence of an anionic counterion effect. This phenomenon should be accounted for when quantitatively analysing drug-membrane interactions in electrostatic terms. (Auth.)

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

    Science.gov (United States)

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

    2009-11-03

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

  16. Moessbauer and NMR study of novel Tin(IV)-lactames

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, Erno; Szalay, Roland; Homonnay, Zoltan, E-mail: homonnay@ludens.elte.hu; Nagy, Sandor [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

    2012-03-15

    N-tributylstannylated 2-pyrrolidinone was reacted with tributyltin triflate in different molar ratios and the complex formation monitored using {sup 1}H-NMR, {sup 13}C-NMR and {sup 119}Sn Moessbauer spectroscopy. Comparing the carbon NMR and tin Moessbauer results, a reaction scheme is suggested for the complexation which assumes the formation of a simultaneously O- and N-tributylstannylated pyrrolidinone cation. The formation of the only O-stannylated pyrrolidinone is also assumed to account for the non-constant Moessbauer parameters of the two tin environments in the distannylated pyrrolidinone cation when the ratio of tributyltin triflate is increased in the reaction.

  17. Solid-state NMR analysis of membrane proteins and protein aggregates by proton detected spectroscopy

    International Nuclear Information System (INIS)

    Zhou, Donghua H.; Nieuwkoop, Andrew J.; Berthold, Deborah A.; Comellas, Gemma; Sperling, Lindsay J.; Tang, Ming; Shah, Gautam J.; Brea, Elliott J.; Lemkau, Luisel R.; Rienstra, Chad M.

    2012-01-01

    Solid-state NMR has emerged as an important tool for structural biology and chemistry, capable of solving atomic-resolution structures for proteins in membrane-bound and aggregated states. Proton detection methods have been recently realized under fast magic-angle spinning conditions, providing large sensitivity enhancements for efficient examination of uniformly labeled proteins. The first and often most challenging step of protein structure determination by NMR is the site-specific resonance assignment. Here we demonstrate resonance assignments based on high-sensitivity proton-detected three-dimensional experiments for samples of different physical states, including a fully-protonated small protein (GB1, 6 kDa), a deuterated microcrystalline protein (DsbA, 21 kDa), a membrane protein (DsbB, 20 kDa) prepared in a lipid environment, and the extended core of a fibrillar protein (α-synuclein, 14 kDa). In our implementation of these experiments, including CONH, CO(CA)NH, CANH, CA(CO)NH, CBCANH, and CBCA(CO)NH, dipolar-based polarization transfer methods have been chosen for optimal efficiency for relatively high protonation levels (full protonation or 100 % amide proton), fast magic-angle spinning conditions (40 kHz) and moderate proton decoupling power levels. Each H–N pair correlates exclusively to either intra- or inter-residue carbons, but not both, to maximize spectral resolution. Experiment time can be reduced by at least a factor of 10 by using proton detection in comparison to carbon detection. These high-sensitivity experiments are especially important for membrane proteins, which often have rather low expression yield. Proton-detection based experiments are expected to play an important role in accelerating protein structure elucidation by solid-state NMR with the improved sensitivity and resolution.

  18. Characterization of ZSM-5 zeolites synthesized by amorphous seed method by 29 Si solid state NMR

    International Nuclear Information System (INIS)

    Souza, Claudia M.G. de; Lau, Yiu Lam; Menezes, Sonia Cabral de

    1993-01-01

    The main objective of this analysis was to study the structure of samples synthesised by the amorphous seed method. The implications of this process upon the synthesized material were unknown. In the synthesis it was used ethanol and amorphous seed, which were added to the final synthesis mixture. It was observed a very significant reduction in the reaction time when compared to conventional synthesis. NMR was used to study the defects in the crystal lattice. Results are presented and discussed

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

    International Nuclear Information System (INIS)

    Hanrahan, Michael P.; Fought, Ellie L.; Windus, Theresa L.; Wheeler, Lance M.; Anderson, Nicholas C.

    2017-01-01

    The chemical and photophysical properties of silicon nanocrystals (Si NCs) are strongly dependent on the chemical composition and structure of their surfaces. Here we use fast magic angle spinning (MAS) and proton detection to enable the rapid acquisition of dipolar and scalar 2D 1 H– 29 Si heteronuclear correlation (HETCOR) solid-state NMR spectra and reveal a molecular picture of hydride-terminated and alkyl-functionalized surfaces of Si NCs produced in a nonthermal plasma. 2D 1 H– 29 Si HETCOR and dipolar 2D 1 H– 1 H multiple-quantum correlation spectra illustrate that resonances from surface mono-, di-, and trihydride groups cannot be resolved, contrary to previous literature assignments. Instead the 2D NMR spectra illustrate that there is large distribution of 1 H and 29 Si chemical shifts for the surface hydride species in both the as-synthesized and functionalized Si NCs. However, proton-detected 1 H– 29 Si refocused INEPT experiments can be used to unambiguously differentiate NMR signals from the different surface hydrides. Varying the 29 Si evolution time in refocused INEPT experiments and fitting the oscillation of the NMR signals allows for the relative populations of the different surface hydrides to be estimated. This analysis confirms that monohydride species are the predominant surface species on the as-synthesized Si NCs. A reduction in the populations of the di- and trihydrides is observed upon functionalization with alkyl groups, consistent with our previous hypothesis that the trihydride, or silyl (*SiH 3 ), group is primarily responsible for initiating surface functionalization reactions. Density functional theory (DFT) calculations were used to obtain quantum chemical structural models of the Si NC surface and reproduce the observed 1 H and 29 Si chemical shifts. Furthermore, the approaches outlined here will be useful to obtain a more detailed picture of surface structures for Si NCs and other hydride-passivated nanomaterials.

  20. Criteria to average out the chemical shift anisotropy in solid-state NMR when irradiated with BABA I, BABA II, and C7 radiofrequency pulse sequences.

    Science.gov (United States)

    Stephane Mananga, Eugene

    2013-01-01

    Floquet-Magnus expansion is used to study the effect of chemical shift anisotropy in solid-state NMR of rotating solids. The chemical shift interaction is irradiated with two types of radiofrequency pulse sequences: BABA and C7. The criteria for the chemical shift anisotropy to be averaged out in each rotor period are obtained. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Multinuclear NMR studies of single lipid bilayers supported in cylindrical aluminum oxide nanopores.

    Science.gov (United States)

    Gaede, Holly C; Luckett, Keith M; Polozov, Ivan V; Gawrisch, Klaus

    2004-08-31

    Lipid bilayers were deposited inside the 0.2 microm pores of anodic aluminum oxide (AAO) filters by extrusion of multilamellar liposomes and their properties studied by 2H, 31P, and 1H solid-state NMR. Only the first bilayer adhered strongly to the inner surface of the pores. Additional layers were washed out easily by a flow of water as demonstrated by 1H magic angle spinning NMR experiments with addition of Pr3+ ions to shift accessible lipid headgroup resonances. A 13 mm diameter Anopore filter of 60 microm thickness oriented approximately 2.5 x 10(-7) mol of lipid as a single bilayer, corresponding to a total membrane area of about 500 cm2. The 2H NMR spectra of chain deuterated POPC are consistent with adsorption of wavy, tubular bilayers to the inner pore surface. By NMR diffusion experiments, we determined the average length of those lipid tubules to be approximately 0.4 microm. There is evidence for a thick water layer between lipid tubules and the pore surface. The ends of tubules are well sealed against the pore such that Pr3+ ions cannot penetrate into the water underneath the bilayers. We successfully trapped poly(ethylene glycol) (PEG) with a molecular weight of 8000 in this water layer. From the quantity of trapped PEG, we calculated an average water layer thickness of 3 nm. Lipid order parameters and motional properties are unperturbed by the solid support, in agreement with existence of a water layer. Such unperturbed, solid supported membranes are ideal for incorporation of membrane-spanning proteins with large intra- and extracellular domains. The experiments suggest the promise of such porous filters as membrane support in biosensors.

  2. Atomic substitutions in synthetic apatite; Insights from solid-state NMR spectroscopy

    Science.gov (United States)

    Vaughn, John S.

    Apatite, Ca5(PO4)3X (where X = F, Cl, or OH), is a unique mineral group capable of atomic substitutions for cations and anions of varied size and charge. Accommodation of differing substituents requires some kind of structural adaptation, e.g. new atomic positions, vacancies, or coupled substitutions. These structural adaptations often give rise to important physicochemical properties relevant to a range of scientific disciplines. Examples include volatile trapping during apatite crystallization, substitution for large radionuclides for long-term storage of nuclear fission waste, substitution for fluoride to improve acid resistivity in dental enamel composed dominantly of hydroxylapatite, and the development of novel biomaterials with enhanced biocompatibility. Despite the importance and ubiquity of atomic substitutions in apatite materials, many of the mechanisms by which these reactions occur are poorly understood. Presence of substituents at dilute concentration and occupancy of disordered atomic positions hinder detection by bulk characterization methods such as X-ray diffraction (XRD) and infrared (IR) spectroscopy. Solid-state nuclear magnetic resonance (NMR) spectroscopy is an isotope-specific structural characterization technique that does not require ordered atomic arrangements, and is therefore well suited to investigate atomic substitutions and structural adaptations in apatite. In the present work, solid-state NMR is utilized to investigate structural adaptations in three different types of apatite materials; a series of near-binary F, Cl apatite, carbonate-hydroxylapatite compositions prepared under various synthesis conditions, and a heat-treated hydroxylapatite enriched in 17O. The results indicate that hydroxyl groups in low-H, near binary F,Cl apatite facilitate solid-solution between F and Cl via column reversals, which result in average hexagonal symmetry despite very dilute OH concentration ( 2 mol percent). In addition, 19F NMR spectra indicate

  3. Detergent/nanodisc screening for high-resolution NMR studies of an integral membrane protein containing a cytoplasmic domain.

    Directory of Open Access Journals (Sweden)

    Christos Tzitzilonis

    Full Text Available Because membrane proteins need to be extracted from their natural environment and reconstituted in artificial milieus for the 3D structure determination by X-ray crystallography or NMR, the search for membrane mimetic that conserve the native structure and functional activities remains challenging. We demonstrate here a detergent/nanodisc screening study by NMR of the bacterial α-helical membrane protein YgaP containing a cytoplasmic rhodanese domain. The analysis of 2D [(15N,(1H]-TROSY spectra shows that only a careful usage of low amounts of mixed detergents did not perturb the cytoplasmic domain while solubilizing in parallel the transmembrane segments with good spectral quality. In contrast, the incorporation of YgaP into nanodiscs appeared to be straightforward and yielded a surprisingly high quality [(15N,(1H]-TROSY spectrum opening an avenue for the structural studies of a helical membrane protein in a bilayer system by solution state NMR.

  4. 'Boomerang'-like insertion of a fusogenic peptide in a lipid membrane revealed by solid-state 19F NMR.

    Science.gov (United States)

    Afonin, Sergii; Dürr, Ulrich H N; Glaser, Ralf W; Ulrich, Anne S

    2004-02-01

    Solid state (19)F NMR revealed the conformation and alignment of the fusogenic peptide sequence B18 from the sea urchin fertilization protein bindin embedded in flat phospholipid bilayers. Single (19)F labels were introduced into nine distinct positions along the wild-type sequence by substituting each hydrophobic amino acid, one by one, with L-4-fluorophenylglycine. Their anisotropic chemical shifts were measured in uniaxially oriented membrane samples and used as orientational constraints to model the peptide structure in the membrane-bound state. Previous (1)H NMR studies of B18 in 30% TFE and in detergent micelles had shown that the peptide structure consists of two alpha-helical segments that are connected by a flexible hinge. This helix-break-helix motif was confirmed here by the solid-state (19)F NMR data, while no other secondary structure (beta-sheet, 3(10)-helix) was compatible with the set of orientational constraints. For both alpha-helical segments we found that the helical conformation extends all the way to the respective N- and C-termini of the peptide. Analysis of the corresponding tilt and azimuthal rotation angles showed that the N-terminal helix of B18 is immersed obliquely into the bilayer (at a tilt angle tau approximately 54 degrees), whereas the C-terminus is peripherally aligned (tau approximately 91 degrees). The azimuthal orientation of the two segments is consistent with the amphiphilic distribution of side-chains. The observed 'boomerang'-like mode of insertion into the membrane may thus explain how peptide binding leads to lipid dehydration and acyl chain perturbation as a prerequisite for bilayer fusion to occur. Copyright 2004 John Wiley & Sons, Ltd.

  5. Isotope labeling strategies for NMR studies of RNA

    International Nuclear Information System (INIS)

    Lu, Kun; Miyazaki, Yasuyuki; Summers, Michael F.

    2010-01-01

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

  6. Studies on supramolecular gel formation using DOSY NMR

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

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

  7. NMR study of novel heavy fermion superconductor CePt{sub 3}Si

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, K. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan)]. E-mail: ueda@sci.u-hyogo.ac.jp; Kohara, T. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Motoyama, G. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Oda, Y. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan)

    2007-03-15

    Si29 NMR experiments were performed to study microscopically the normal and superconducting states in Si29 enriched CePt{sub 3}Si. A Si29 Knight shift parallel to the c-axis did not decrease below the T{sub c}. The 1/T{sub 1} result taken with a field cycling method showed no distinct coherence peak just below T{sub c} and a steep decrease below T{sub c} on cooling. The estimated value of the superconducting energy gap was about 2{delta}=3.6k{sub B}T{sub c}. These results may be an evidence for triplet pairing superconductivity.

  8. Identification of aquatically available carbon from algae through solution-state NMR of whole (13)C-labelled cells.

    Science.gov (United States)

    Akhter, Mohammad; Dutta Majumdar, Rudraksha; Fortier-McGill, Blythe; Soong, Ronald; Liaghati-Mobarhan, Yalda; Simpson, Myrna; Arhonditsis, George; Schmidt, Sebastian; Heumann, Hermann; Simpson, André J

    2016-06-01

    Green algae and cyanobacteria are primary producers with profound impact on food web functioning. Both represent key carbon sources and sinks in the aquatic environment, helping modulate the dissolved organic matter balance and representing a potential biofuel source. Underlying the impact of algae and cyanobacteria on an ecosystem level is their molecular composition. Herein, intact (13)C-labelled whole cell suspensions of Chlamydomonas reinhardtii, Chlorella vulgaris and Synechocystis were studied using a variety of 1D and 2D (1)H/(13)C solution-state nuclear magnetic resonance (NMR) spectroscopic experiments. Solution-state NMR spectroscopy of whole cell suspensions is particularly relevant as it identifies species that are mobile (dissolved or dynamic gels), 'aquatically available' and directly contribute to the aquatic carbon pool upon lysis, death or become a readily available food source on consumption. In this study, a wide range of metabolites and structural components were identified within the whole cell suspensions. In addition, significant differences in the lipid/triacylglyceride (TAG) content of green algae and cyanobacteria were confirmed. Mobile species in algae are quite different from those in abundance in 'classic' dissolved organic matter (DOM) indicating that if algae are major contributors to DOM, considerable selective preservation of minor components (e.g. sterols) or biotransformation would have to occur. Identifying the metabolites and dissolved components within algal cells by NMR permits future studies of carbon transfer between species and through the food chain, whilst providing a foundation to better understand the role of algae in the formation of DOM and the sequestration/transformation of carbon in aquatic environments.

  9. Characterisation of different polymorphs of tris(8-hydroxyquinolinatoaluminium(III using solid-state NMR and DFT calculations

    Directory of Open Access Journals (Sweden)

    Periasamy N

    2009-11-01

    Full Text Available Abstract Background Organic light emitting devices (OLED are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato-aluminium(III, known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. Results We report here 27Al one-dimensional (1D and two-dimensional (2D multiple-quantum magic-angle spinning (MQMAS NMR studies of the meridional (α-phase and the facial (δ-phase isomeric forms of Alq3. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory quantum-chemical calculations. We have also studied solvated phase of Alq3 containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the α-phase and the δ-phase, although the fluorescence emission shows no substantial difference between the α-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq3 has similar XRD patterns and quadrupolar parameters to that of the α-phase. Conclusion The 2D MQMAS experiments have shown that all the different modifications of Alq3 have 27Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq3 containing ethanol has structural difference from the α-phase of Alq3 (containing meridional isomer from the solid-state NMR studies

  10. Characterisation of different polymorphs of tris(8-hydroxyquinolinato)aluminium(III) using solid-state NMR and DFT calculations.

    Science.gov (United States)

    Goswami, Mithun; Nayak, Pabitra K; Periasamy, N; Madhu, P K

    2009-11-09

    Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. We report here 27Al one-dimensional (1D) and two-dimensional (2D) multiple-quantum magic-angle spinning (MQMAS) NMR studies of the meridional (alpha-phase) and the facial (delta-phase) isomeric forms of Alq3. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory) quantum-chemical calculations. We have also studied solvated phase of Alq3 containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the alpha-phase and the delta-phase, although the fluorescence emission shows no substantial difference between the alpha-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq3 has similar XRD patterns and quadrupolar parameters to that of the alpha-phase. The 2D MQMAS experiments have shown that all the different modifications of Alq3 have 27Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq3 containing ethanol has structural difference from the alpha-phase of Alq3 (containing meridional isomer) from the solid-state NMR studies. Solid-state NMR can hence be

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

    KAUST Repository

    Abou-Hamad, E.; Babaa, M.-R.; Bouhrara, M.; Kim, Y.; Saih, Y.; Dennler, S.; Mauri, F.; Basset, Jean-Marie; Goze-Bac, C.; Wå gberg, T.

    2011-01-01

    We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled

  12. NMR study of spin dynamics in mesoscopic molecular clusters

    Science.gov (United States)

    Borsa, Ferdinando

    1998-03-01

    Recent published and umpublished work regarding the magnetic properties and the spin dynamics of molecules containing rings of 6,8 and 10 spins and of molecules containing clusters of 8 and 12 spins are reviewed. The 1H nuclear spin-lattice relaxation rate (NSLR) and the Muon Spin Resonance relaxation in Mn12 (A.Lascialfari, D.Gatteschi, F.Borsa, A.Shastri, Z.H.Jang and P.Carretta, Phys.Rev. B 1 January 1998) and Fe8 clusters are presented and discussed with regards to the high temperature spin dynamics of the Mn (Fe) magnetic moments and with regards to the low temperature superparamagnetic behavior. 1H and 63Cu NMR results are presented for two "quantum" spin rings : Cu6 and Cu8. The Cu6 is a weakly coupled (J/k=60K) ferromagnetic S=1/2 spin ring while Cu8 is a strongly coupled (J/k greater than 400K) antiferromagnetic S=1/2 spin ring.The dependence of the NSRL from temperature and from applied magnetic field are analyzed in terms of the calculated magnetic energy levels of the magnetic ring. The values of the energy gap between the ground state and the first excited state are extracted from the exponential decrease of the NSLR as the temperature is lowered. The results in the Cu ( S=1/2) "quantum" rings are compared with the results in "quantum" chains and ladders and with the results in "classical" Fe (S=5/2) antiferromagnetic rings : Fe6 and Fe10 (A.Lascialfari, D.Gatteschi, F.Borsa and A.Cornia , Phys.Rev. 55B,14341,1997) ).

  13. Effects of sample preparation conditions on biomolecular solid-state NMR lineshapes

    Energy Technology Data Exchange (ETDEWEB)

    Jakeman, David L.; Mitchell, Dan J.; Shuttleworth, Wendy A.; Evans, Jeremy N.S. [Washington State University, Department of Biochemistry and Biophysics (United States)

    1998-10-15

    Sample preparation conditions with the 46 kDa enzyme complex of 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase, shikimate-3-phosphate (S3P) and glyphosate (GLP) have been examined in an attempt to reduce linewidths in solid-state NMR spectra. The linewidths of {sup 13}P resonances associated with enzyme bound S3P and GLP in the lyophilized ternary complex have been reduced to 150 {+-} 12 Hz and 125 {+-} 7 Hz respectively, by a variety of methods involving additives and freezing techniques.

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

    Science.gov (United States)

    Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike; Auken, Esben; Barfod, Adrian A. S.; Ferré, Ty P. A.; Vilhelmsen, Troels N.; Johnson, Carole D.; Christiansen, Anders V.

    2017-11-01

    The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.

  15. Solid-state 13C magic angle spinning NMR spectroscopy characterization of particle size structural variations in synthetic nanodiamonds

    International Nuclear Information System (INIS)

    Alam, Todd M.

    2004-01-01

    Solid-state 13 C magic angle spinning (MAS) NMR spectroscopy has been used to quantify the different carbon species observed in synthetically produced nanodiamonds. Two different diamond-like carbon species were observed using 13 C MAS NMR, which have been attributed to a highly ordered crystalline diamond phase and a disordered crystalline diamond phase. The relative ratio of these different diamond phases was found to vary with the particle size of the nanodiamond materials

  16. Crystal structure and tautomerism of Pigment Yellow 138 determined by X-ray powder diffraction and solid-state NMR

    DEFF Research Database (Denmark)

    Gumbert, Silke D.; Körbitzer, Meike; Alig, Edith

    2016-01-01

    The crystal structure of C.I. Pigment Yellow 138 was determined from X-ray powder diffraction data using real-space methods with subsequent Rietveld refinements. The tautomeric state was investigated by solid-state 1D and 2D multinuclear NMR experiments. In the crystals, the compound exhibits...... the NH-tautomer with a hydrogen atom situated at the nitrogen of the quinoline moiety. Direct evidence of the presence of the NH-tautomer is provided by 1H–14N HMQC solid-state NMR at very fast MAS. Solid-state dispersion-corrected density functional theory calculations with BLYP-D3 confirm...

  17. Quantum tunneling of magnetization in molecular nanomagnet Fe8 studied by NMR

    International Nuclear Information System (INIS)

    Maegawa, Satoru; Ueda, Miki

    2003-01-01

    Magnetization and NMR measurements have been performed for single crystals of molecular magnet Fe8. The field and temperature dependences of magnetization below 25 K are well described in terms of the isolated clusters with the total spin S=10. The stepwise recoveries of 1 H-NMR signals at the level crossing fields caused by the resonant quantum tunneling of magnetization were observed below 400 mK. The recovery of the NMR signals are explained by the fluctuation caused by the transition between the energy states of Fe magnetizations governed by Landau-Zener quantum transitions

  18. A 55Mn NMR study of the La0.75Sr0.25MnO3 nanoparticles

    International Nuclear Information System (INIS)

    Rybicki, D.; Sikora, M.; Kapusta, Cz.; Riedi, P.C.; Jirak, Z.; Knizek, K.; Marysko, M.; Pollert, E.; Veverka, P.

    2006-01-01

    We report on a 55 Mn NMR study of the La 0.75 Sr 0.25 MnO 3 nanoparticles of the average grain size 33 nm and 114 nm at 4.2 K and 77 K and at applied field of 0, 0.2 and 0.5T. A dominant signal from the double exchange (DE) controlled metallic ferromagnetic interior of the grains as well as a small signal from insulating ferromagnetic regions is observed. From a comparison with bulk magnetization measurement the thickness of the nonferromagnetic outer layer of the grains and the amount of the ferromagnetic insulating phase was determined. The relative amount of these phases with respect to the ferromagnetic metallic phase increases with decreasing grain size. The DE line in the NMR spectrum shows a frequency shift with applied field according to a full 55 Mn gyromagnetic ratio. A value of the demagnetizing field close to zero is obtained, which indicates a single domain state of the nanoparticles. For the sample with larger grains a higher NMR enhancement is observed, which indicates a higher magnetic susceptibility of the sample at the NMR frequencies. A comparison with the NMR data obtained on a microcrystalline material is made. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Probing membrane protein structure using water polarization transfer solid-state NMR.

    Science.gov (United States)

    Williams, Jonathan K; Hong, Mei

    2014-10-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected (1)H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins. Copyright © 2014 Elsevier Inc. All

  20. High resolution NMR theory and chemical applications

    CERN Document Server

    Becker, Edwin D

    1999-01-01

    High Resolution NMR provides a broad treatment of the principles and theory of nuclear magnetic resonance (NMR) as it is used in the chemical sciences. It is written at an "intermediate" level, with mathematics used to augment, rather than replace, clear verbal descriptions of the phenomena. The book is intended to allow a graduate student, advanced undergraduate, or researcher to understand NMR at a fundamental level, and to see illustrations of the applications of NMR to the determination of the structure of small organic molecules and macromolecules, including proteins. Emphasis is on the study of NMR in liquids, but the treatment also includes high resolution NMR in the solid state and the principles of NMR imaging and localized spectroscopy. Careful attention is given to developing and interrelating four approaches - steady state energy levels, the rotating vector picture, the density matrix, and the product operator formalism. The presentation is based on the assumption that the reader has an acquaintan...

  1. Ground-state properties of K-isotopes from laser and $\\beta$-NMR spectroscopy

    CERN Multimedia

    Lievens, P; Rajabali, M M; Krieger, A R

    By combining high-resolution laser spectroscopy with $\\beta$-NMR spectroscopy on polarized K-beams we aim to establish the ground-state spins and magnetic moments of the neutron-rich $^{48,49,50,51}$K isotopes from N=29 to N=32. Spins and magnetic moments of the odd-K isotopes up to N=28 reveal an inversion of the ground-state, from the normal $\\,{I}$=3/2 ($\\pi{d}_{3/2}^{-1}$) in $^{41-45}$K$\\to\\,{I}$=1/2 ($\\pi{s}_{1/2}^{-1}$) in $^{47}$K. This inversion of the proton single particle levels is related to the strong proton $d_{3/2}$ - neutron $f_{7/2}$ interaction which lowers the energy of the $\\pi{d}_{3/2}$ single particle state when filling the $\

  2. High resolution deuterium NMR studies of bacterial metabolism

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-12-25

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

  3. High resolution deuterium NMR studies of bacterial metabolism

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  4. Hydrogen-1 NMR relaxation time studies in membrane: anesthetic systems

    International Nuclear Information System (INIS)

    Pinto, L.M.A.; Fraceto, L.; Paula, E. de; Franzoni, L.; Spisni, A.

    1997-01-01

    The study of local anesthetics'(LA) interaction with model phospholipid membranes is justified by the direct correlation between anesthetic's hydrophobicity and its potency/toxicity. By the same reason, uncharged LA species seems to play a crucial role in anesthesia. Most clinically used LA are small amphiphilics with a protonated amine group (pKa around 8). Although both charged (protonated) and uncharged forms can coexist at physiological pH, it has been shown (Lee, Biochim. Biophys. Acta 514:95, 1978; Screier et al. Biochim. Biophys. Acta 769:231, 1984) that the real anesthetic pka can be down-shifted, due to differential partition into membranes, increasing the ratio of uncharged species at pH 7.4. We have measured 1 H-NMR longitudinal relaxation times (T 1 ) for phospholipid and three local anesthetics (tetracaine, lidocaine, benzocaine), in sonicated vesicles at a 3:1 molar ratio. All the LA protons have shown smaller T 1 in this system than in isotropic phases, reflecting LA immobilization caused by insertion in the membrane. T 1 values for the lipid protons in the presence of LA were analyzed, in an attempt to identify specific LA:lipid contact regions. (author)

  5. Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR.

    Science.gov (United States)

    Kim, Sung Joon; Chang, James; Singh, Manmilan

    2015-01-01

    Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Structure and dynamics of cationic membrane peptides and proteins: Insights from solid-state NMR

    Science.gov (United States)

    Hong, Mei; Su, Yongchao

    2011-01-01

    Many membrane peptides and protein domains contain functionally important cationic Arg and Lys residues, whose insertion into the hydrophobic interior of the lipid bilayer encounters significant energy barriers. To understand how these cationic molecules overcome the free energy barrier to insert into the lipid membrane, we have used solid-state NMR spectroscopy to determine the membrane-bound topology of these peptides. A versatile array of solid-state NMR experiments now readily yields the conformation, dynamics, orientation, depth of insertion, and site-specific protein–lipid interactions of these molecules. We summarize key findings of several Arg-rich membrane peptides, including β-sheet antimicrobial peptides, unstructured cell-penetrating peptides, and the voltage-sensing helix of voltage-gated potassium channels. Our results indicate the central role of guanidinium-phosphate and guanidinium-water interactions in dictating the structural topology of these cationic molecules in the lipid membrane, which in turn account for the mechanisms of this functionally diverse class of membrane peptides. PMID:21344534

  7. Characterization of the ground state dynamics of proteorhodopsin by NMR and optical spectroscopies

    International Nuclear Information System (INIS)

    Stehle, Jochen; Scholz, Frank; Löhr, Frank; Reckel, Sina; Roos, Christian; Blum, Michaela; Braun, Markus; Glaubitz, Clemens; Dötsch, Volker; Wachtveitl, Josef; Schwalbe, Harald

    2012-01-01

    We characterized the dynamics of proteorhodopsin (PR), solubilized in diC7PC, a detergent micelle, by liquid-state NMR spectroscopy at T = 323 K. Insights into the dynamics of PR at different time scales could be obtained and dynamic hot spots could be identified at distinct, functionally relevant regions of the protein, including the BC loop, the EF loop, the N-terminal part of helix F and the C-terminal part of helix G. We further characterize the dependence of the photocycle on different detergents (n-Dodecyl β-D-maltoside DDM; 1,2-diheptanoyl-sn-glycero-3-phosphocholine diC7PC) by ultrafast time-resolved UV/VIS spectroscopy. While the photocycle intermediates of PR in diC7PC and DDM exhibit highly similar spectral characteristics, significant changes in the population of these intermediates are observed. In-situ NMR experiments have been applied to characterize structural changes during the photocycle. Light-induced chemical shift changes detected during the photocycle in diC7PC are very small, in line with the changes in the population of intermediates in the photocycle of proteorhodopsin in diC7PC, where the late O-intermediate populated in DDM is missing and the population is shifted towards an equilibrium of intermediates states (M, N, O) without accumulation of a single populated intermediate.

  8. Contribution of exogenous substrates to acetyl coenzyme A: Measurement by 13C NMR under non-steady-state conditions

    International Nuclear Information System (INIS)

    Malloy, C.R.; Jeffrey, F.M.H.; Thompson, J.R.; Sherry, A.D.

    1990-01-01

    A method is presented for the rapid determination of substrate selection in a manner that is not restricted to conditions of metabolic and isotopic steady state. Competition between several substrates can be assessed directly and continuously in a single experiment, allowing the effect of interventions to be studied. It is shown that a single proton-decoupled 13 C NMR spectrum of glutamate provides a direct measure of the contribution of exogenous 13 C-labeled substrates to acetyl-CoA without measurement of oxygen consumption and that steady-state conditions need not apply. Two sets of experiments were performed: one in which a metabolic steady state but a non-steady-state 13 C distribution was achieved and another in which both metabolism and labeling were not at steady state. In the first group, isolated rat hearts were supplied with [1,2- 13 C]acetate, [3- 13 C]lactate, and unlabeled glucose. 13 C NMR spectra of extracts from hearts perfused under identical conditions for 5 or 30 min were compared. In spite of significant differences in the spectra, the measured contributions of acetate, lactate, and unlabeled sources to acetyl-CoA were the same. In the second set of experiments, the same group of labeled substrates was used in a regional ischemia model in isolated rabbit hearts to show regional differences in substrate utilization under both metabolic and isotopic non steady state. The time resolution of these measurements may not be limited by technical contraints but by the rate of carbon flux in the citric acid cycle. Although this technique is demonstrated for the heart, it is applicable to all tissues

  9. 11B nutation NMR study of powdered borosilicates

    International Nuclear Information System (INIS)

    Woo, Ae Ja; Yang, Kyung Hwa; Han, Duk Young

    1998-01-01

    In this work, we applied the 1D 11 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO 2 -B 2 O 3 ). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11 B nutation NMR experiment. The 11 B NMR parameters, quadrupole coupling constants (e 2 qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed

  10. Measurement of Lipid Accumulation in Chlorella vulgaris via Flow Cytometry and Liquid-State ¹H NMR Spectroscopy for Development of an NMR-Traceable Flow Cytometry Protocol

    Science.gov (United States)

    Bono Jr., Michael S.; Garcia, Ravi D.; Sri-Jayantha, Dylan V.; Ahner, Beth A.; Kirby, Brian J.

    2015-01-01

    In this study, we cultured Chlorella vulgaris cells with a range of lipid contents, induced via nitrogen starvation, and characterized them via flow cytometry, with BODIPY 505/515 as a fluorescent lipid label, and liquid-state 1H NMR spectroscopy. In doing so, we demonstrate the utility of calibrating flow cytometric measurements of algal lipid content using triacylglyceride (TAG, also known as triacylglycerol or triglyceride) content per cell as measured via quantitative 1H NMR. Ensemble-averaged fluorescence of BODIPY-labeled cells was highly correlated with average TAG content per cell measured by bulk NMR, with a linear regression yielding a linear fit with r 2 = 0.9974. This correlation compares favorably to previous calibrations of flow cytometry protocols to lipid content measured via extraction, and calibration by NMR avoids the time and complexity that is generally required for lipid quantitation via extraction. Flow cytometry calibrated to a direct measurement of TAG content can be used to investigate the distribution of lipid contents for cells within a culture. Our flow cytometry measurements showed that Chlorella vulgaris cells subjected to nitrogen limitation exhibited higher mean lipid content but a wider distribution of lipid content that overlapped the relatively narrow distribution of lipid content for replete cells, suggesting that nitrogen limitation induces lipid accumulation in only a subset of cells. Calibration of flow cytometry protocols using direct in situ measurement of TAG content via NMR will facilitate rapid development of more precise flow cytometry protocols, enabling investigation of algal lipid accumulation for development of more productive algal biofuel feedstocks and cultivation protocols. PMID:26267664

  11. Measurement of lipid accumulation in Chlorella vulgaris via flow cytometry and liquid-state ¹H NMR spectroscopy for development of an NMR-traceable flow cytometry protocol.

    Directory of Open Access Journals (Sweden)

    Michael S Bono

    Full Text Available In this study, we cultured Chlorella vulgaris cells with a range of lipid contents, induced via nitrogen starvation, and characterized them via flow cytometry, with BODIPY 505/515 as a fluorescent lipid label, and liquid-state 1H NMR spectroscopy. In doing so, we demonstrate the utility of calibrating flow cytometric measurements of algal lipid content using triacylglyceride (TAG, also known as triacylglycerol or triglyceride content per cell as measured via quantitative 1H NMR. Ensemble-averaged fluorescence of BODIPY-labeled cells was highly correlated with average TAG content per cell measured by bulk NMR, with a linear regression yielding a linear fit with r2 = 0.9974. This correlation compares favorably to previous calibrations of flow cytometry protocols to lipid content measured via extraction, and calibration by NMR avoids the time and complexity that is generally required for lipid quantitation via extraction. Flow cytometry calibrated to a direct measurement of TAG content can be used to investigate the distribution of lipid contents for cells within a culture. Our flow cytometry measurements showed that Chlorella vulgaris cells subjected to nitrogen limitation exhibited higher mean lipid content but a wider distribution of lipid content that overlapped the relatively narrow distribution of lipid content for replete cells, suggesting that nitrogen limitation induces lipid accumulation in only a subset of cells. Calibration of flow cytometry protocols using direct in situ measurement of TAG content via NMR will facilitate rapid development of more precise flow cytometry protocols, enabling investigation of algal lipid accumulation for development of more productive algal biofuel feedstocks and cultivation protocols.

  12. Measurement of lipid accumulation in Chlorella vulgaris via flow cytometry and liquid-state ¹H NMR spectroscopy for development of an NMR-traceable flow cytometry protocol.

    Science.gov (United States)

    Bono, Michael S; Garcia, Ravi D; Sri-Jayantha, Dylan V; Ahner, Beth A; Kirby, Brian J

    2015-01-01

    In this study, we cultured Chlorella vulgaris cells with a range of lipid contents, induced via nitrogen starvation, and characterized them via flow cytometry, with BODIPY 505/515 as a fluorescent lipid label, and liquid-state 1H NMR spectroscopy. In doing so, we demonstrate the utility of calibrating flow cytometric measurements of algal lipid content using triacylglyceride (TAG, also known as triacylglycerol or triglyceride) content per cell as measured via quantitative 1H NMR. Ensemble-averaged fluorescence of BODIPY-labeled cells was highly correlated with average TAG content per cell measured by bulk NMR, with a linear regression yielding a linear fit with r2 = 0.9974. This correlation compares favorably to previous calibrations of flow cytometry protocols to lipid content measured via extraction, and calibration by NMR avoids the time and complexity that is generally required for lipid quantitation via extraction. Flow cytometry calibrated to a direct measurement of TAG content can be used to investigate the distribution of lipid contents for cells within a culture. Our flow cytometry measurements showed that Chlorella vulgaris cells subjected to nitrogen limitation exhibited higher mean lipid content but a wider distribution of lipid content that overlapped the relatively narrow distribution of lipid content for replete cells, suggesting that nitrogen limitation induces lipid accumulation in only a subset of cells. Calibration of flow cytometry protocols using direct in situ measurement of TAG content via NMR will facilitate rapid development of more precise flow cytometry protocols, enabling investigation of algal lipid accumulation for development of more productive algal biofuel feedstocks and cultivation protocols.

  13. Selected topics from recent NMR studies of organolithium compounds

    Directory of Open Access Journals (Sweden)

    Günther Harald

    1999-01-01

    Full Text Available After a short introduction to NMR spectroscopy of alkali and alkaline earth metals the review concentrates on NMR investigations of organolithium compounds. The isotopic fingerprint method, which rests on deuterium-induced isotope shifts for 6Li resonances, is introduced and exemplified with applications from the aggregation behavior of cyclopropyllithium systems and mixed aggregate formation between methyllithium and lithium salts. In the following chapter, one- and two-dimensional pulse experiments, both for homo- and for heteronuclear spin systems are discussed. Finally, the structural aspects associated with benzyllithium are outlined and the formation of polylithium systems by lithium reduction of biphenylenes is described.

  14. Solid state NMR sequential resonance assignments and conformational analysis of the 2x10.4 kDa dimeric form of the Bacillus subtilis protein Crh

    Energy Technology Data Exchange (ETDEWEB)

    Boeckmann, Anja [Institut de Biologie et Chimie des Proteines, C.N.R.S UMR 5086 (France)], E-mail: a.bockmann@ibcp.fr; Lange, Adam [Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR (Germany); Galinier, Anne [Institut de Biologie Structurale et Microbiologie, C.N.R.S UPR 9043 (France); Luca, Sorin [Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR (Germany); Giraud, Nicolas; Juy, Michel [Institut de Biologie et Chimie des Proteines, C.N.R.S UMR 5086 (France); Heise, Henrike [Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR (Germany); Montserret, Roland; Penin, Francois [Institut de Biologie et Chimie des Proteines, C.N.R.S UMR 5086 (France); Baldus, Marc [Max-Planck-Institute for Biophysical Chemistry, Solid-state NMR (Germany)], E-mail: maba@mpibpc.mpg.de

    2003-12-15

    Solid state NMR sample preparation and resonance assignments of the U-[{sup 13}C,{sup 15}N] 2x10.4 kDa dimeric form of the regulatory protein Crh in microcrystalline, PEG precipitated form are presented. Intra- and interresidue correlations using dipolar polarization transfer methods led to nearly complete sequential assignments of the protein, and to 88% of all {sup 15}N, {sup 13}C chemical shifts. For several residues, the resonance assignments differ significantly from those reported for the monomeric form analyzed by solution state NMR. Dihedral angles obtained from a TALOS-based statistical analysis suggest that the microcrystalline arrangement of Crh must be similar to the domain-swapped dimeric structure of a single crystal form recently solved using X-ray crystallography. For a limited number of protein residues, a remarkable doubling of the observed NMR resonances is observed indicative of local static or dynamic conformational disorder. Our study reports resonance assignments for the largest protein investigated by solid state NMR so far and describes the conformational dimeric variant of Crh with previously unknown chemical shifts.

  15. Combined Approach for the Structural Characterization of Alkali Fluoroscandates: Solid-State NMR, Powder X-ray Diffraction, and Density Functional Theory Calculations.

    Science.gov (United States)

    Rakhmatullin, Aydar; Polovov, Ilya B; Maltsev, Dmitry; Allix, Mathieu; Volkovich, Vladimir; Chukin, Andrey V; Boča, Miroslav; Bessada, Catherine

    2018-02-05

    The structures of several fluoroscandate compounds are presented here using a characterization approach combining powder X-ray diffraction and solid-state NMR. The structure of K 5 Sc 3 F 14 was fully determined from Rietveld refinement performed on powder X-ray diffraction data. Moreover, the local structures of NaScF 4 , Li 3 ScF 6 , KSc 2 F 7 , and Na 3 ScF 6 compounds were studied in detail from solid-state 19 F and 45 Sc NMR experiments. The 45 Sc chemical shift ranges for six- and seven-coordinated scandium environments were defined. The 19 F chemical shift ranges for bridging and terminal fluorine atoms were also determined. First-principles calculations of the 19 F and 45 Sc NMR parameters were carried out using plane-wave basis sets and periodic boundary conditions (CASTEP), and the results were compared with the experimental data. A good agreement between the calculated shielding constants and experimental chemical shifts was obtained. This demonstrates the good potential of computational methods in spectroscopic assignments of solid-state 45 Sc NMR spectroscopy.

  16. Manifestations of classical physics in the quantum evolution of correlated spin states in pulsed NMR experiments.

    Science.gov (United States)

    Ligare, Martin

    2016-05-01

    Multiple-pulse NMR experiments are a powerful tool for the investigation of molecules with coupled nuclear spins. The product operator formalism provides a way to understand the quantum evolution of an ensemble of weakly coupled spins in such experiments using some of the more intuitive concepts of classical physics and semi-classical vector representations. In this paper I present a new way in which to interpret the quantum evolution of an ensemble of spins. I recast the quantum problem in terms of mixtures of pure states of two spins whose expectation values evolve identically to those of classical moments. Pictorial representations of these classically evolving states provide a way to calculate the time evolution of ensembles of weakly coupled spins without the full machinery of quantum mechanics, offering insight to anyone who understands precession of magnetic moments in magnetic fields.

  17. High Pressure ZZ-Exchange NMR Reveals Key Features of Protein Folding Transition States.

    Science.gov (United States)

    Zhang, Yi; Kitazawa, Soichiro; Peran, Ivan; Stenzoski, Natalie; McCallum, Scott A; Raleigh, Daniel P; Royer, Catherine A

    2016-11-23

    Understanding protein folding mechanisms and their sequence dependence requires the determination of residue-specific apparent kinetic rate constants for the folding and unfolding reactions. Conventional two-dimensional NMR, such as HSQC experiments, can provide residue-specific information for proteins. However, folding is generally too fast for such experiments. ZZ-exchange NMR spectroscopy allows determination of folding and unfolding rates on much faster time scales, yet even this regime is not fast enough for many protein folding reactions. The application of high hydrostatic pressure slows folding by orders of magnitude due to positive activation volumes for the folding reaction. We combined high pressure perturbation with ZZ-exchange spectroscopy on two autonomously folding protein domains derived from the ribosomal protein, L9. We obtained residue-specific apparent rates at 2500 bar for the N-terminal domain of L9 (NTL9), and rates at atmospheric pressure for a mutant of the C-terminal domain (CTL9) from pressure dependent ZZ-exchange measurements. Our results revealed that NTL9 folding is almost perfectly two-state, while small deviations from two-state behavior were observed for CTL9. Both domains exhibited large positive activation volumes for folding. The volumetric properties of these domains reveal that their transition states contain most of the internal solvent excluded voids that are found in the hydrophobic cores of the respective native states. These results demonstrate that by coupling it with high pressure, ZZ-exchange can be extended to investigate a large number of protein conformational transitions.

  18. 31P-NMR studies on turnover rates of phosphocreatine in superfused cerebral tissues

    International Nuclear Information System (INIS)

    Bachelard, H.S.; Cox, D.W.G.; Morris, P.G.; Feeney, J.

    1986-01-01

    The spectra obtained using 31 P-NMR on superfused cerebral cortex preparations in vitro are comparable with those reported for in vivo studies. The rate constants for creatine kinase, measured by saturation transfer techniques, were 0.23s -1 for the forward reaction (transfer of phosphate from creatine phosphate to ADP) and 0.55s -1 for the reverse reaction. Calculated flux rates were similar for the two reactions, at ca 0.7 μmol s -1 g -1 . Mild hypoxia caused a 30 to 50% decrease in creatine phosphate without detectable change in ATP;the rate constant for the forward reaction was increased by about 50%. The sensitivity of the energy state was similar to that found in parallel experiments for synaptic function. In contrast, lowering the glucose to 0.5 mM had no effect on the 31 P-NMR spectrum, so confirming that the energy state is far less sensitive to hypoglycaemia than synaptic function (which becomes impaired below 2mM glucose). Further lowering of the glucose to 0.2mM caused a 30% decrease in creatine phosphate, and unlike hypoxia, the ATP also fell by 30%. No change was detected in the rate constant. The results of preliminary experiments on even lower glucose (0.1mM) suggest that the rate constant may increase under these conditions but this needs confirmation from further experiments

  19. Metabolic studies with NMR spectroscopy of the alga Dunaliella salina trapped within agarose beads.

    Science.gov (United States)

    Bental, M; Pick, U; Avron, M; Degani, H

    1990-02-22

    A technique for the entrapment of the unicellular algae Dunaliella salina in agarose beads and their perfusion during NMR measurements is presented. The trapped cells maintained their ability to proliferate under normal growth conditions, and remained viable and stable under steady-state conditions for long periods during NMR measurements. Following osmotic shock in the dark, prominent changes were observed in the intracellular level of ATP and polyphosphates, but little to no changes in the intracellular pH or orthoposphate content. When cells were subjected to hyperosmotic shock, the ATP level decreased. The content of NMR-visible polyphosphates decreased as well, presumably due to the production of longer, NMR-invisible structures. Following hypoosmotic shock, the ATP content increased and longer polyphosphates were broken down to shorter, more mobile polymers.

  20. NMR study of thermoresponsive block copolymer in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

    2016-01-01

    Roč. 217, č. 12 (2016), s. 1370-1375 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * NMR * NOESY Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

  1. 235U NMR study of the itinerant antiferromagnet USb2

    International Nuclear Information System (INIS)

    Kato, Harukazu; Sakai, Hironori; Ikushima, Kenji; Kambe, Shinsaku; Tokunaga, Yo; Aoki, Dai; Haga, Yoshinori; O-bar nuki, Yoshichika; Yasuoka, Hiroshi; Walstedt, Russell E.

    2005-01-01

    We have succeeded in resolving a 235 U antiferromagnetic nuclear magnetic resonance (AFNMR) signal using 235 U-enriched samples of USb 2 . The uranium hyperfine field and coupling constant estimated for this compound are consistent with those from other experiments. This is the first reported observation of 235 U NMR in conducting host material

  2. Dynamics in photosynthetic transient complexes studied by paramagnetic NMR spectroscopy

    NARCIS (Netherlands)

    Scanu, Sandra

    2013-01-01

    This PhD thesis focuses on fundamental aspects of protein-protein interactions. A multidisciplinary methodology for the detection and visualization of transient, lowly-populated encounter protein complexes is described. The new methodology combined paramagnetic NMR spectroscopy with computational

  3. Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Takegoshi, K., E-mail: takeyan@kuchem.kyoto-u.ac.jp; Miyazawa, Norihiro [Division of Chemistry, Graduate School of Science, Kyoto University, 606-8502 Kyoto (Japan); Sharma, Kshama [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Madhu, P. K. [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

    2015-04-07

    We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

  4. Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

    Science.gov (United States)

    Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

    2015-04-01

    We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

  5. Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

    International Nuclear Information System (INIS)

    Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

    2015-01-01

    We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order

  6. Phase-alternated composite π/2 pulses for solid state quadrupole echo NMR spectroscopy

    International Nuclear Information System (INIS)

    Ramamoorthy, A.; Narasimhan, P.T.

    1991-01-01

    Phase-alternated composite π/2 pulses have been constructed for spin I=1 to overcome quadrupole interaction effects in solid state nuclear magnetic resonance(NMR) spectroscopy. Magnus expansion approach is used to design these sequences in a manner similar to the NMR coherent averaging theory. It is inferred that the symmetric phase-alternated composite π/2 pulses reported here are quite successful in producing quadrupole echo free phase distortions. This effectiveness of the present composite pulses is due to the fact that most of them are of shorter durations as compared to the ones reported in literature. In this theoretical procedure, irreducible spherical tensor operator formalism is employed to simplify the complexity involved in the evaluation of Magnus expansion terms. It has been argued in this paper that composite π/2 pulse sequences for this purpose can also be derived from the broadband inversion π pulses which are designed to compensate electric field gradient(efg) inhomogeniety in spin I=1 nuclear quadrupole resonance(NQR) spectroscopy. (author). 28 refs

  7. NMR study of lignins model-trimers of the type 5-5'/β-0-4'

    International Nuclear Information System (INIS)

    Pilo-Veloso, Dorila; Stefani, Guglielmo M.; Drumond, Mariza Guimaraes; Alves, Vera Lucia

    1997-01-01

    Lignins are very abundant macromolecules in vegetables. In addition to be an important sub product in pulp and paper industry, these compounds are also a source of chemical raw materials. One of the most important methodologies for the chemical structural study of these compounds is solid state nuclear magnetic resonance. This work presents the NMR study of three unedited lignins compounds derived from Eucalyptus grandis

  8. Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

    International Nuclear Information System (INIS)

    Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G.; Boffo, Elisangela F.; Figueira, Glyn M.

    2012-01-01

    The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, 1 H HR-MAS NMR and 1 H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

  9. Authenticity study of Phyllanthus species by NMR and FT-IR Techniques coupled with chemometric methods

    Directory of Open Access Journals (Sweden)

    Maiara S. Santos

    2012-01-01

    Full Text Available The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as "quebra-pedras" in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques.

  10. Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

    2012-07-01

    The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

  11. Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

    2012-07-01

    The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

  12. A comparative study of bone scintigraphy and NMR for vertebral diseases

    International Nuclear Information System (INIS)

    Nakatani, Mariko; Sekiya, Toru; Hata, Yuichi; Mori, Yutaka; Yasuda, Masanobu; Kawakami, Kenji; Tada, Sinpei

    1985-01-01

    A comparative study of NMR and bone scintigraphy was performed in vertebral disorders, and the significance of both modalities was evaluated. Twelve patients with various vertebral abnormalities including ten cases of vertebral metastases, one case of cervical caries and one case of Granular cell tumor of L3, were examined. In 4 patients, NMR showed abnormalities in the same regions as the bone scintigrams. In another 3 patients. NMR did not show the disorders reported on bone scintigrams. This may be due to the low NMR sensitivity to tiny infiltration of tumor cells in the bone marrow. In 3 out of the remaining 5 patients, NMR demonstrated abnormal findings, whilst the bone scintigrams were normal. Previous bone scintigrams in these patients before treatment had shown abnormal accumulation of activity in the region of abnormal NMR findings. This may be due to the fact that NMR detects the irreversible change of bone marrow, and bone scintigram demonstrates the turn over of bone minerals. This limited experience suggests that both madalities are complementary in the evaluation of vertebral abnormalities. (author)

  13. Automated sample preparation station for studying self-diffusion in porous solids with NMR spectroscopy

    Science.gov (United States)

    Hedin, Niklas; DeMartin, Gregory J.; Reyes, Sebastián C.

    2006-03-01

    In studies of gas diffusion in porous solids with nuclear magnetic resonance (NMR) spectroscopy the sample preparation procedure becomes very important. An apparatus is presented here that pretreats the sample ex situ and accurately sets the desired pressure and temperature within the NMR tube prior to its introduction in the spectrometer. The gas manifold that supplies the NMR tube is also connected to a microbalance containing another portion of the same sample, which is kept at the same temperature as the sample in the NMR tube. This arrangement permits the simultaneous measurement of the adsorption loading on the sample, which is required for the interpretation of the NMR diffusion experiments. Furthermore, to ensure a good seal of the NMR tube, a hybrid valve design composed of titanium, a Teflon® seat, and Kalrez® O-rings is utilized. A computer controlled algorithm ensures the accuracy and reproducibility of all the procedures, enabling the NMR diffusion experiments to be performed at well controlled conditions of pressure, temperature, and amount of gas adsorbed on the porous sample.

  14. 31P NMR study of phosphate metabolites in intact developing seeds of wheat, soybean and mustard

    International Nuclear Information System (INIS)

    Gambhir, P.N.; Pande, P.C.; Ratcliffe, R.G.

    1994-01-01

    The study of 31 P NMR spectra of intact developing seeds of wheat, soybean and mustard and its possible use for assessing the relative degree of hypoxia under in vivo conditions are reported. 7 refs., 2 figs

  15. An improved ultrafast 2D NMR experiment: Towards atom-resolved real-time studies of protein kinetics at multi-Hz rates

    International Nuclear Information System (INIS)

    Gal, Maayan; Kern, Thomas; Schanda, Paul; Frydman, Lucio; Brutscher, Bernhard

    2009-01-01

    Multidimensional NMR spectroscopy is a well-established technique for the characterization of structure and fast-time-scale dynamics of highly populated ground states of biological macromolecules. The investigation of short-lived excited states that are important for molecular folding, misfolding and function, however, remains a challenge for modern biomolecular NMR techniques. Off-equilibrium real-time kinetic NMR methods allow direct observation of conformational or chemical changes by following peak positions and intensities in a series of spectra recorded during a kinetic event. Because standard multidimensional NMR methods required to yield sufficient atom-resolution are intrinsically time-consuming, many interesting phenomena are excluded from real-time NMR analysis. Recently, spatially encoded ultrafast 2D NMR techniques have been proposed that allow one to acquire a 2D NMR experiment within a single transient. In addition, when combined with the SOFAST technique, such ultrafast experiments can be repeated at high rates. One of the problems detected for such ultrafast protein NMR experiments is related to the heteronuclear decoupling during detection with interferences between the pulses and the oscillatory magnetic field gradients arising in this scheme. Here we present a method for improved ultrafast data acquisition yielding higher signal to noise and sharper lines in single-scan 2D NMR spectra. In combination with a fast-mixing device, the recording of 1 H- 15 N correlation spectra with repetition rates of up to a few Hertz becomes feasible, enabling real-time studies of protein kinetics occurring on time scales down to a few seconds

  16. Membrane lipids protected from oxidation by red wine tannins: a proton NMR study.

    Science.gov (United States)

    Furlan, Aurélien L; Jobin, Marie-Lise; Buchoux, Sébastien; Grélard, Axelle; Dufourc, Erick J; Géan, Julie

    2014-12-01

    Dietary polyphenols widespread in vegetables and beverages like red wine and tea have been reported to possess antioxidant properties that could have positive effects on human health. In this study, we propose a new in situ and non-invasive method based on proton liquid-state nuclear magnetic resonance (NMR) to determine the antioxidant efficiency of red wine tannins on a twice-unsaturated phospholipid, 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLiPC), embedded in a membrane model. Four tannins were studied: (+)-catechin (C), (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG). The lipid degradation kinetics was determined by measuring the loss of the bis-allylic protons during oxidation induced by a radical initiator, 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH). The antioxidant efficiency, i.e. the ability of tannins to slow down the lipid oxidation rate, was shown to be higher for galloylated tannins, ECG and EGCG. Furthermore, the mixture of four tannins was more efficient than the most effective tannin, EGCG, demonstrating a synergistic effect. To better understand the antioxidant action mechanism of polyphenols on lipid membranes, the tannin location was investigated by NMR and molecular dynamics. A correlation between antioxidant action of tannins and their location at the membrane interface (inserted at the glycerol backbone level) could thus be established. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  17. Structural characterization of supramolecular assemblies by {sup 13}C spin dilution and 3D solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Habenstein, Birgit; Loquet, Antoine; Giller, Karin; Becker, Stefan; Lange, Adam, E-mail: adla@nmr.mpibpc.mpg.de [Max Planck Institute for Biophysical Chemistry, Department of NMR-based Structural Biology (Germany)

    2013-01-15

    {sup 13}C spin diluted protein samples can be produced using [1-{sup 13}C] and [2-{sup 13}C]-glucose (Glc) carbon sources in the bacterial growth medium. The {sup 13}C spin dilution results in favorable {sup 13}C spectral resolution and polarization transfer behavior. We recently reported the combined use of [1-{sup 13}C]- and [2-{sup 13}C]-Glc labeling to facilitate the structural analysis of insoluble and non-crystalline biological systems by solid-state NMR (ssNMR), including sequential assignment, detection of long-range contacts and structure determination of macromolecular assemblies. In solution NMR the beneficial properties of sparsely labeled samples using [2-{sup 13}C]-glycerol ({sup 13}C labeled C{alpha} sites on a {sup 12}C diluted background) have recently been exploited to provide a bi-directional assignment method (Takeuchi et al. in J Biomol NMR 49(1):17-26, 2011 ). Inspired by this approach and our own recent results using [2-{sup 13}C]-Glc as carbon sources for the simplification of ssNMR spectra, we present a strategy for a bi-directional sequential assignment of solid-state NMR resonances and additionally the detection of long-range contacts using the combination of {sup 13}C spin dilution and 3D NMR spectroscopy. We illustrate our results with the sequential assignment and the collection of distance restraints on an insoluble and non-crystalline supramolecular assembly, the Salmonella typhimurium type III secretion system needle.

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

    Science.gov (United States)

    2015-01-01

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

  19. NMR structural studies of oligosaccharides and other natural products

    DEFF Research Database (Denmark)

    Kjærulff, Louise

    produce secondary metabolites for signaling and competing against other organisms, and these molecules are important in drug discovery due to their inherent biological activities. From a marine Photobacterium (P. halotolerans) we isolated the solonamides and the ngercheumicins, two families of cyclic...... through the nJCH correlation, this experiment has exciting applications for configurational assignment of e.g. carbohydrates and for residual dipolar couplings. Identification of known molecules and discovery of novel molecules are other important applications of NMR spectroscopy. Bacteria and fungi....... fijiensis, was also investigated for production of novel secondary metabolites, and a new pyranonigrin (E) was isolated and structure elucidated by NMR spectroscopy along with JBIR-74 and decumbenone A, two known metabolites previously isolated from Aspergillus and Penicillium species. Oligosaccharides...

  20. High Resolution NMR Studies of Encapsulated Proteins In Liquid Ethane

    Science.gov (United States)

    Peterson, Ronald W.; Lefebvre, Brian G.; Wand, A. Joshua

    2005-01-01

    Many of the difficulties presented by large, aggregation-prone, and membrane proteins to modern solution NMR spectroscopy can be alleviated by actively seeking to increase the effective rate of molecular reorientation. An emerging approach involves encapsulating the protein of interest within the protective shell of a reverse micelle, and dissolving the resulting particle in a low viscosity fluid, such as the short chain alkanes. Here we present the encapsulation of proteins with high structural fidelity within reverse micelles dissolved in liquid ethane. The addition of appropriate co-surfactants can significantly reduce the pressure required for successful encapsulation. At these reduced pressures, the viscosity of the ethane solution is low enough to provide sufficiently rapid molecular reorientation to significantly lengthen the spin-spin NMR relaxation times of the encapsulated protein. PMID:16028922

  1. The flexibility of SIMPSON and SIMMOL for numerical simulations in solid-and liquid-state NMR spectroscopy

    International Nuclear Information System (INIS)

    Vosegaard, T.; Malmendal, A.; Nielsen, N.C.

    2002-01-01

    Addressing the need for numerical simulations in the design and interpretation of advanced solid- and liquid-state NMR experiments, we present a number of novel features for numerical simulations based on the SIMPSON and SIMMOL open source software packages. Major attention is devoted to the flexibility of these Tcl-interfaced programs for numerical simulation of NMR experiments being complicated by demands for efficient powder averaging, large spin systems, and multiple-pulse rf irradiation. These features are exemplified by fast simulation of second-order quadrupolar powder patterns using crystallite interpolation, analysis of rotary resonance triple-quantum excitation for quadrupolar nuclei, iterative fitting of MQ-MAS spectra by combination of SIMIPSON and MINUIT, simulation of multiple-dimensional PISEMA-type correlation experiments for macroscopically oriented membrane proteins, simulation of Hartman-Hahn polarization transfers in liquid-state NMR, and visualization of the spin evolution under complex composite broad-band excitation pulses. (author)

  2. A comparison study of PET, NMR, and CT imaging in cerebral ischemia

    International Nuclear Information System (INIS)

    Babikian, V.L.; Ford, C.S.; Buonanno, F.S.; Kistler, J.P.; Ackerman, R.H.; Alpert, N.M.; Correia, J.A.; Johnson, K.A.; Buxton, R.B.

    1987-01-01

    Whether ischemia without infarction produces recognizable changes in relaxation times of ischemic but viable brain is an important, unresolved issue. Therefore, a study was initiated of patients with cerebral ischemia, using positron emission tomography (PET), NMR, and computed tomography (CT) to compare and contrast the pathophysiologic information provided by each and to study the issue of whether cerebral ischemia without infarction can be appreciated by proton NMR imaging. Here the initial results are reported. 4 refs.; 2 figs.; 1 table

  3. NMR spectroscopy study of agar-based polymers electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, R.I.; Tambelli, C.E. [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Fac. de Zootecnia e Engenharia de Alimentos; Raphael, E. [Universidade Federal de Sao Joao del-Rey (UFSJ), MG (Brazil). Dept. de Ciencias Naturais; Silva, I.D.A.; Magon, C.J.; Donoso, J.P. [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2012-07-01

    Full text: This communication presents the results of preparation and characterization of transparent films obtained from agar and acetic acid. The films were characterized by electrochemical impedance spectroscopy (EIS) and nuclear magnetic resonance (NMR). The film formed by agar (Sigma Aldrich) was dispersed in water and kept under stirring and heating at 100 deg C. Next, glycerol, formaldehyde and different quantities of acetic acid (25 and 50 wt%) were added to this solution. The obtained solution was placed on a glass plate and left to dry for 48 hours in oven at 50 deg C to obtain the films, which were kept under vacuum before characterization. The ionic conductivity of the films display an Arrhenius behavior with activation energy E{sub a} = 78 (25 wt% of acetic acid) and E{sub a} = 87 kJ/mol (50 wt% of acetic acid). The conductivity values were 3:0 X 10{sup -6} and 1:2 X 10{sup -4} S/cm at room temperature and 4:4 X 10{sup -4} and 1:5 X 10{sup -3}S/cm at 70 deg C, for the 25 and 50 wt% of acetic acid respectively. To investigate the mechanism of protonic conduction in the polymer proton conductor proton NMR measurements were performed in the temperature range 200-370 K. The {sup 1}H-NMR results exhibit the qualitative feature associated with the proton mobility, namely the presence of well defined {sup 1}H spin-lattice relaxation maxima at 300 K. Activation energy of the order of 40 kJ/mol was obtained from the {sup 1}H-NMR line narrowing data. The ionic conductivity of the film combined with their transparency, flexibility, homogeneity and good adhesion to the glasses or metals indicate that agar-based SPEs are promising materials for used on optoelectronic applications. (author)

  4. In situ NMR studies of reactions on catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Haw, James F [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry

    1994-12-31

    Zeolites are useful in the synthesis of fine chemicals. The systematic understanding of organic chemistry of zeolite catalysis may contribute to: the elucidation of reaction mechanisms of existing catalytic processes; the discovery of new catalytic reactions; the application of zeolite catalysis to the synthesis of fine chemicals. This work presents species of zeolites identified by in situ NMR; reactions of organic chemicals on zeolites and proposes mechanisms as well as reactivity trends 3 refs., 7 tabs.

  5. Study on the interactions PVC/plasticizers by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Maria I.B.; Monteiro, Elisabeth E.C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas; Harris, Robin [Durham Univ. (United Kingdom). Dept. of Chemistry

    1992-12-31

    The nature of the interactions between PVC and plasticizers as di-butyl phthalate and di-2-ethyl-hexyl phthalate can be investigated using proton/carbon-13 NMR techniques. The measurements of T{sub 1} for protons and carbon-13 and T{sub 1} P for protons can provide a good source of information about the complex behaviour for those two systems which were investigated. (author) 14 refs., 5 figs., 1 tab.

  6. NMR Studies of Lithium Iodide Based Solid Electrolytes

    DEFF Research Database (Denmark)

    Dupree, R.; Howells, R. J.; Hooper, A.

    1983-01-01

    In mixture of LiI with γAl2O3 the ionic conductivity is found to increase by up to three orders of magnitude over pure LiI. NMR measurements of7Li relaxation times were performed on both anhydrous LiI and a mixture of LiI with 30m/o γAl2O3. The relaxation is found to be purely dipolar in origin f...

  7. Characterization of the Vibrio cholerae extracellular matrix: a top-down solid-state NMR approach.

    Science.gov (United States)

    Reichhardt, Courtney; Fong, Jiunn C N; Yildiz, Fitnat; Cegelski, Lynette

    2015-01-01

    Bacterial biofilms are communities of bacterial cells surrounded by a self-secreted extracellular matrix. Biofilm formation by Vibrio cholerae, the human pathogen responsible for cholera, contributes to its environmental survival and infectivity. Important genetic and molecular requirements have been identified for V. cholerae biofilm formation, yet a compositional accounting of these parts in the intact biofilm or extracellular matrix has not been described. As insoluble and non-crystalline assemblies, determinations of biofilm composition pose a challenge to conventional biochemical and biophysical analyses. The V. cholerae extracellular matrix composition is particularly complex with several proteins, complex polysaccharides, and other biomolecules having been identified as matrix parts. We developed a new top-down solid-state NMR approach to spectroscopically assign and quantify the carbon pools of the intact V. cholerae extracellular matrix using ¹³C CPMAS and ¹³C{(¹⁵N}, ¹⁵N{³¹P}, and ¹³C{³¹P}REDOR. General sugar, lipid, and amino acid pools were first profiled and then further annotated and quantified as specific carbon types, including carbonyls, amides, glycyl carbons, and anomerics. In addition, ¹⁵N profiling revealed a large amine pool relative to amide contributions, reflecting the prevalence of molecular modifications with free amine groups. Our top-down approach could be implemented immediately to examine the extracellular matrix from mutant strains that might alter polysaccharide production or lipid release beyond the cell surface; or to monitor changes that may accompany environmental variations and stressors such as altered nutrient composition, oxidative stress or antibiotics. More generally, our analysis has demonstrated that solid-state NMR is a valuable tool to characterize complex biofilm systems. Copyright © 2014. Published by Elsevier B.V.

  8. The contribution of solid-state NMR spectroscopy to understanding biomineralization: Atomic and molecular structure of bone

    Science.gov (United States)

    Duer, Melinda J.

    2015-04-01

    Solid-state NMR spectroscopy has had a major impact on our understanding of the structure of mineralized tissues, in particular bone. Bone exemplifies the organic-inorganic composite structure inherent in mineralized tissues. The organic component of the extracellular matrix in bone is primarily composed of ordered fibrils of collagen triple-helical molecules, in which the inorganic component, calcium phosphate particles, composed of stacks of mineral platelets, are arranged around the fibrils. This perspective argues that key factors in our current structural model of bone mineral have come about through NMR spectroscopy and have yielded the primary information on how the mineral particles interface and bind with the underlying organic matrix. The structure of collagen within the organic matrix of bone or any other structural tissue has yet to be determined, but here too, this perspective shows there has been real progress made through application of solid-state NMR spectroscopy in conjunction with other techniques. In particular, NMR spectroscopy has highlighted the fact that even within these structural proteins, there is considerable dynamics, which suggests that one should be cautious when using inherently static structural models, such as those arising from X-ray diffraction analyses, to gain insight into molecular roles. It is clear that the NMR approach is still in its infancy in this area, and that we can expect many more developments in the future, particularly in understanding the molecular mechanisms of bone diseases and ageing.

  9. Solid-State NMR Spectroscopy Proves the Presence of Penta-coordinated Sc Sites in MIL-100(Sc).

    Science.gov (United States)

    Giovine, Raynald; Volkringer, Christophe; Ashbrook, Sharon E; Trébosc, Julien; McKay, David; Loiseau, Thierry; Amoureux, Jean-Paul; Lafon, Olivier; Pourpoint, Frédérique

    2017-07-18

    Advanced solid-state NMR methods and first-principles calculations demonstrate for the first time the formation of penta-coordinated scandium sites. These coordinatively unsaturated sites were shown during the thermal activation of scandium-based metal-organic frameworks (MOFs). A 45 Sc NMR experiment allows their specific observation in activated Sc 3 BTB 2 (H 3 BTB=1,3,5-tris(4-carboxyphenyl)benzene) and MIL-100(Sc) MOFs. The assignment of the ScO 5 groups is supported by the DFT calculations of NMR parameters. The presence of ScO 5 Lewis acid sites in MIL-100(Sc) explains furthermore its catalytic activity. The first NMR experiment to probe 13 C- 45 Sc distances is also introduced. This advanced solid-state NMR pulse sequence allows the demonstration of the shrinkage of the MIL-100(Sc) network when the activation temperature is raised. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Brain oxidative metabolism of the newborn dog: correlation between 31P NMR spectroscopy and pyridine nucleotide redox state.

    Science.gov (United States)

    Mayevsky, A; Nioka, S; Subramanian, V H; Chance, B

    1988-04-01

    The effects of both anoxia and short- and long-term hypoxia on brain oxidative metabolism were studied in newborn dogs. Oxidative metabolism was evaluated by two independent measures: in vivo continuous monitoring of mitochondrial NADH redox state and energy stores as calculated from the phosphocreatine (PCr)/Pi levels measured by 31P nuclear magnetic resonance (NMR) spectroscopy. The hemodynamic response to low oxygen supply was further evaluated by measuring the changes in the reflected light intensity at 366 nm (the excitation wavelength for NADH). The animal underwent surgery and was prepared for monitoring of the two signals (NADH and PCr/Pi). It was then placed inside a Phosphoenergetics 260-80 NMR spectrometer magnet with a 31-cm bore. Each animal (1-21 days old) was exposed to short-term anoxia or hypoxia as well as to long-term hypoxia (1-2 h). The results can be summarized as follow: (a) In the normoxic brain, the ratio between PCr and Pi was greater than 1 (1.2-1.4), while under hypoxia or asphyxia a significant decrease that was correlated to the FiO2 levels was recorded. (b) A clear correlation was found between the decrease in PCr/Pi values and the increased NADH redox state developed under decreased O2 supply to the brain. (c) Exposing the animal to moderately long-term hypoxia led to a stabilized low-energy state of the brain with a good recovery after rebreathing normal air. (d) Under long-term and severe hypoxia, the microcirculatory autoregulatory mechanism was damaged and massive vasoconstriction was optically recorded simultaneously with a significant decrease in PCr/Pi values.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. A neutron-X-ray, NMR and calorimetric study of glassy Probucol synthesized using containerless techniques

    International Nuclear Information System (INIS)

    Weber, J.K.R.; Benmore, C.J.; Tailor, A.N.; Tumber, S.K.; Neuefeind, J.; Cherry, B.; Yarger, J.L.; Mou, Q.; Weber, W.; Byrn, S.R.

    2013-01-01

    Highlights: • Acoustic levitation was used to make phase-pure glassy forms of pharmaceutical compounds. • Neutrons, X-rays and NMR were used to characterize the glasses. • The glass comprised of slightly distorted molecules packed in a random network. • Potential for new drug synthesis routes is discussed. - Abstract: Acoustic levitation was used to trap 1–3 mm diameter drops of Probucol and other pharmaceutical materials in containerless conditions. Samples were studied in situ using X-ray diffraction and ex situ using neutron diffraction, NMR and DSC techniques. The materials were brought into non-equilibrium states by supersaturating solutions or by supercooling melts. The glass transition and crystallization temperatures of glassy Probucol were 29 ± 1 and 71 ± 1 °C respectively. The glassy form was stable with a shelf life of at least 8 months. A neutron/X-ray difference function of the glass showed that while molecular sub-groups remain rigid, many of the hydrogen correlations observed in the crystal become smeared out in the disordered material. The glass is principally comprised of slightly distorted Form I Probucol molecules with disordered packing rather than large changes in the individual molecular structure. Avoiding surface contact-induced nucleation provided access to highly non-equilibrium phases and enabled synthesis of phase-pure glasses

  12. NMR Techniques in Metabolomic Studies: A Quick Overview on Examples of Utilization.

    Science.gov (United States)

    Kruk, Joanna; Doskocz, Marek; Jodłowska, Elżbieta; Zacharzewska, Anna; Łakomiec, Joanna; Czaja, Kornelia; Kujawski, Jacek

    2017-01-01

    Metabolomics is a rapidly developing branch of science that concentrates on identifying biologically active molecules with potential biomarker properties. To define the best biomarkers for diseases, metabolomics uses both models (in vitro, animals) and human, as well as, various techniques such as mass spectroscopy, gas chromatography, liquid chromatography, infrared and UV-VIS spectroscopy and nuclear magnetic resonance. The last one takes advantage of the magnetic properties of certain nuclei, such as 1 H, 13 C, 31 P, 19 F, especially their ability to absorb and emit energy, what is crucial for analyzing samples. Among many spectroscopic NMR techniques not only one-dimensional (1D) techniques are known, but for many years two-dimensional (2D, for example, COSY, DOSY, JRES, HETCORE, HMQS), three-dimensional (3D, DART-MS, HRMAS, HSQC, HMBC) and solid-state NMR have been used. In this paper, authors taking apart fundamental division of nuclear magnetic resonance techniques intend to shown their wide application in metabolomic studies, especially in identifying biomarkers.

  13. A neutron-X-ray, NMR and calorimetric study of glassy Probucol synthesized using containerless techniques

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.K.R., E-mail: rweber@anl.gov [Materials Development, Inc., Arlington Heights, IL 60004 (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); Benmore, C.J. [Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Physics, Arizona State University, AZ 85287 (United States); Tailor, A.N.; Tumber, S.K. [Materials Development, Inc., Arlington Heights, IL 60004 (United States); Neuefeind, J. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cherry, B. [Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Yarger, J.L. [Department of Physics, Arizona State University, AZ 85287 (United States); Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Mou, Q. [Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Weber, W. [Department of Physics, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Byrn, S.R. [Department of Industrial and Physical Pharmacy, Purdue University, IN 47907 (United States)

    2013-10-16

    Highlights: • Acoustic levitation was used to make phase-pure glassy forms of pharmaceutical compounds. • Neutrons, X-rays and NMR were used to characterize the glasses. • The glass comprised of slightly distorted molecules packed in a random network. • Potential for new drug synthesis routes is discussed. - Abstract: Acoustic levitation was used to trap 1–3 mm diameter drops of Probucol and other pharmaceutical materials in containerless conditions. Samples were studied in situ using X-ray diffraction and ex situ using neutron diffraction, NMR and DSC techniques. The materials were brought into non-equilibrium states by supersaturating solutions or by supercooling melts. The glass transition and crystallization temperatures of glassy Probucol were 29 ± 1 and 71 ± 1 °C respectively. The glassy form was stable with a shelf life of at least 8 months. A neutron/X-ray difference function of the glass showed that while molecular sub-groups remain rigid, many of the hydrogen correlations observed in the crystal become smeared out in the disordered material. The glass is principally comprised of slightly distorted Form I Probucol molecules with disordered packing rather than large changes in the individual molecular structure. Avoiding surface contact-induced nucleation provided access to highly non-equilibrium phases and enabled synthesis of phase-pure glasses.

  14. Theoretical study of NMR, infrared and Raman spectra on triple-decker phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga, 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic properties of multi-decker phthalocyanines were studied by theoretical calculation. Electronic structures, excited processes at multi-states, isotropic chemical shifts of {sup 13}C, {sup 14}N and {sup 1}H-nuclear magnetic resonance (NMR), principle V-tensor in electronic field gradient (EFG) tensor and asymmetry parameters (η), vibration mode in infrared (IR) and Raman spectra of triple-decker phthalocyanines were calculated by density functional theory (DFT) and time-dependent DFT using B3LYP as basis function. Electron density distribution was delocalized on the phthalocyanine rings with electron static potential. Considerable separation of chemical shifts in {sup 13}C, {sup 14}N and {sup 1}H-NMR was originated from nuclear spin interaction between nitrogen and carbon atoms, nuclear quadrupole interaction based on EFG and η of central metal under crystal field. Calculated optical absorption at multi-excited process was derived from overlapping π-orbital on the phthalocyanine rings. The vibration modes in IR and Raman spectra were based on in-plane deformation and stretching vibrations of metal-ligand coordination bond on the deformed structure.

  15. Studies on Photodarkening Effect in Glassy As2S3 Using High Field NMR

    Science.gov (United States)

    Hari, Parameswar; Su, Tining; Taylor, Craig; Reyes, Arneil; Kuhns, Phil; Moulton, William; Sullivan, N. S.

    2001-03-01

    Photodarkening, or the shift of the optical absorption edge to smaller energies after excitation with light whose energy is near that of the optical band edge, has been studied in many chalcogenide glasses for many years. Recently we have conducted nuclear magnetic resonance (NMR) studies of 75As in glassy As2S3 at 17T . We compared the 75As NMR lineshape in glassy As2S3 before and after irradiation at 77K. After irradiation at 514.5 nm for 230 hours with 170 mW/cm2 there is a subtle change in the NMR lineshape. This change is reversible on annealing at 200 C for 1.75 hours. We will discuss the implications of this result based on NMR lineshape analysis using an exact solution of the spin 3/2 Hamiltonian

  16. An in-cell NMR study of monitoring stress-induced increase of cytosolic Ca{sup 2+} concentration in HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, Dambarudhar Shiba Sankar; Haremaki, Takahiro; Hamatsu, Jumpei; Inoue, Jin; Kamoshida, Hajime; Ikeya, Teppei; Mishima, Masaki [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan); Mikawa, Tsutomu [Cellular and Molecular Biology Unit, RIKEN Advanced Science Institute, Wako-shi, Saitama 351-0198 (Japan); Hayashi, Nobuhiro [Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 B-1, Nagatsuda-chou, Midori-ku, Yokohama, Kanagawa 226-8501 (Japan); Shirakawa, Masahiro [Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Ito, Yutaka, E-mail: ito-yutaka@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan)

    2013-09-06

    Highlights: •We performed time-resolved NMR observations of calbindin D{sub 9k} in HeLa cells. •Stress-induced increase of cytosolic Ca{sup 2+} concentration was observed by in-cell NMR. •Calbindin D{sub 9k} showed the state-transition from Mg{sup 2+}- to Ca{sup 2+}-bound state in cells. •We provide a useful tool for in situ monitoring of the healthiness of the cells. -- Abstract: Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. The lifetime of in-cell NMR samples is however much shorter than that in culture media, presumably because of various stresses as well as the nutrient depletion in the anaerobic environment within the NMR tube. It is well known that Ca{sup 2+}-bursts occur in HeLa cells under various stresses, hence the cytosolic Ca{sup 2+} concentration can be regarded as a good indicator of the healthiness of cells in NMR tubes. In this study, aiming at monitoring the states of proteins resulting from the change of cytosolic Ca{sup 2+} concentration during experiments, human calbindin D{sub 9k} (P47M + C80) was used as the model protein and cultured HeLa cells as host cells. Time-resolved measurements of 2D {sup 1}H–{sup 15}N SOFAST–HMQC experiments of calbindin D{sub 9k} (P47M + C80) in HeLa cells showed time-dependent changes in the cross-peak patterns in the spectra. Comparison with in vitro assignments revealed that calbindin D{sub 9k} (P47M + C80) is initially in the Mg{sup 2+}-bound state, and then gradually converted to the Ca{sup 2+}-bound state. This conversion process initiates after NMR sample preparation. These results showed, for the first time, that cells inside the NMR tube were stressed, presumably because of cell precipitation, the lack of oxygen and nutrients, etc., thereby releasing Ca{sup 2+} into cytosol during the measurements. The results demonstrated that in-cell NMR can monitor the state transitions of stimulated cells through the observation of

  17. A combined NMR and XRD study of AFI and AEL type molecular sieves

    NARCIS (Netherlands)

    Peeters, M.P.J.; Ven, van de L.J.M.; Haan, de J.W.; Hooff, van J.H.C.

    1993-01-01

    Calcined dehydrated AlPO4-5 was studied by x-ray powder diffraction, 31P MAS, and 27Al double-resonance (DOR) NMR. Three crystallog. different sites can be distinguished in the structure of dehydrated AlPO4-5 in the ratio 1:1:1. The obsd. splitting of the NMR spectra is correlated to the line width

  18. Experiments and strategies for the assignment of fully13 C/15N-labelled polypeptides by solid state NMR

    International Nuclear Information System (INIS)

    Straus, Suzana K.; Bremi, Tobias; Ernst, Richard R.

    1998-01-01

    High-resolution heteronuclear NMR correlation experiments and strategies are proposed for the assignment of fully 13 C/ 15 N-labelled polypeptides in the solid state. By the combination of intra-residue and inter-residue 13 C- 15 N correlation experiments with 13 C- 13 C spin-diffusion studies, it becomes feasible to partially assign backbone and side-chain resonances in solid proteins. The performance of sequences using 15 N instead of 13 C detection is evaluated regarding sensitivity and resolution for a labelled dipeptide (L-Val-L-Phe). The techniques are used for a partial assignment of the 15 N and 13 C resonances in human ubiquitin

  19. Measurement of conformational constraints in an elastin-mimetic protein by residue-pair selected solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Mei [Iowa State University, Department of Chemistry (United States)], E-mail: mhong@iastate.edu; McMillan, R. Andrew; Conticello, Vincent P. [Emory University, Department of Chemistry (United States)

    2002-02-15

    We introduce a solid-state NMR technique for selective detection of a residue pair in multiply labeled proteins to obtain site-specific structural constraints. The method exploits the frequency-offset dependence of cross polarization to achieve {sup 13}CO{sub i} {sup {yields}} {sup 15}N{sub i} {sup {yields}} {sup 13}C{alpha}{sub i} transfer between two residues. A {sup 13}C, {sup 15}N-labeled elastin mimetic protein (VPGVG){sub n} is used to demonstrate the method. The technique selected the Gly3 C{alpha} signal while suppressing the Gly5 C{alpha} signal, and allowed the measurement of the Gly3 C{alpha} chemical shift anisotropy to derive information on the protein conformation. This residue-pair selection technique should simplify the study of protein structure at specific residues.

  20. Measurement of conformational constraints in an elastin-mimetic protein by residue-pair selected solid-state NMR

    International Nuclear Information System (INIS)

    Hong, Mei; McMillan, R. Andrew; Conticello, Vincent P.

    2002-01-01

    We introduce a solid-state NMR technique for selective detection of a residue pair in multiply labeled proteins to obtain site-specific structural constraints. The method exploits the frequency-offset dependence of cross polarization to achieve 13 CO i → 15 N i → 13 Cα i transfer between two residues. A 13 C, 15 N-labeled elastin mimetic protein (VPGVG) n is used to demonstrate the method. The technique selected the Gly3 Cα signal while suppressing the Gly5 Cα signal, and allowed the measurement of the Gly3 Cα chemical shift anisotropy to derive information on the protein conformation. This residue-pair selection technique should simplify the study of protein structure at specific residues

  1. NMR Study of Solvation Effect on Geometry of Proton-Bound Homodimers of Increasing Size

    KAUST Repository

    Gurinov, Andrei A.; Denisov, Gleb S.; Borissova, Alexandra O.; Goloveshkin, Alexander S.; Greindl, Julian; Limbach, Hans-Heinrich; Shenderovich, Ilya G.

    2017-01-01

    Hydrogen bond geometries in the proton-bound homodimers of quinoline and acridine derivatives in an aprotic polar solution have been experimentally studied using 1H NMR at 120 K. The reported results show that increase of the dielec-tric permittivity of the medium results in contraction of the N…N distance. The degree of contraction depends on the homodimer's size and its substituent-specific solvation features. Neither of these effects can be reproduced using conven-tional implicit solvent models employed in computational studies. In general, the N…N distance in the homodimers of pyridine, quinoline, and acridine derivatives decreases in the sequence gas phase > solid state > polar solvent.

  2. NMR Study of Solvation Effect on Geometry of Proton-Bound Homodimers of Increasing Size

    KAUST Repository

    Gurinov, Andrei A.

    2017-10-24

    Hydrogen bond geometries in the proton-bound homodimers of quinoline and acridine derivatives in an aprotic polar solution have been experimentally studied using 1H NMR at 120 K. The reported results show that increase of the dielec-tric permittivity of the medium results in contraction of the N…N distance. The degree of contraction depends on the homodimer\\'s size and its substituent-specific solvation features. Neither of these effects can be reproduced using conven-tional implicit solvent models employed in computational studies. In general, the N…N distance in the homodimers of pyridine, quinoline, and acridine derivatives decreases in the sequence gas phase > solid state > polar solvent.

  3. Indirect detection in solid state NMR: An illustrious history and a bright future

    Science.gov (United States)

    Tycko, Robert

    2018-03-01

    Many of us have a love/hate relationship with nuclear magnetic resonance (NMR). We love the information content of NMR data, which provides us with essential information about structure, dynamics, and material properties that is not available from any other measurement, and we love the fact that NMR methods can be applied to almost any problem in almost any area of science. But we hate the low sensitivity of NMR, which forces us to make big samples, spend many tedious hours or days taking data, or live with marginal signal-to-noise.

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  5. NMR studies of chemical structural variation of insoluble organic matter from different carbonaceous chondrite groups

    Science.gov (United States)

    Cody, George D.; Alexander, Conel M. O.'D.

    2005-02-01

    Solid-state 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic experiments have been performed on isolated meteoritic Insoluble Organic Matter (IOM) spanning four different carbonaceous chondrite meteorite groups; a CR2 (EET92042), a CI1 (Orgueil), a CM2 (Murchison), and the unique C2 meteorite, Tagish Lake. These solid state NMR experiments reveal considerable variation in bulk organic composition across the different meteorite group's IOM. The fraction of aromatic carbon increases as CR2 meteorite groups. Single pulse (SP) 13C magic angle spinning (MAS) NMR experiments reveal the presence of nanodiamonds with an apparent concentration ranking in the IOM of CR2 IOM of all four meteoritic IOM fractions are highly substituted. Fast spinning SP 1H MAS NMR spectral data combined with other NMR experimental data reveal that the average hydrogen content of sp 3 bonded carbon functional groups is low, requiring a high degree of aliphatic chain branching in each IOM fraction. The variation in chemistry across the meteorite groups is consistent with alteration by low temperature chemical oxidation. It is concluded that such chemistry principally affected the aliphatic moieties whereas the aromatic moieties and nanodiamonds may have been largely unaffected.

  6. NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

    Directory of Open Access Journals (Sweden)

    Fen Yue

    2018-04-01

    Full Text Available Hydrothermal carbonization (HTC is a valuable approach to convert furfural residue (FR into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H13C HSQC etc. especially 1D selective gradient total correlation spectroscopy (TOCSY NMR were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies. Keywords: NMR, Hydrothermal carbonization, Furfural residue, Stock process water

  7. Characterization of a Cyclic Nucleotide-Activated K+ Channel and its Lipid Environment by Using Solid-State NMR Spectroscopy

    NARCIS (Netherlands)

    Cukkemane, A.A.; Baldus, M.

    2013-01-01

    Voltage-gated ion channels are large tetrameric multidomain membrane proteins that play crucial roles in various cellular transduction pathways. Because of their large size and domain-related mobility, structural characterization has proved challenging. We analyzed high-resolution solid-state NMR

  8. A solution-state NMR approach to elucidating pMDI-wood bonding mechanisms in loblolly pine

    Science.gov (United States)

    Daniel Joseph Yelle

    2009-01-01

    Solution-state NMR spectroscopy is a powerful tool for unambiguously determining the existence or absence of covalent chemical bonds between wood components and adhesives. Finely ground wood cell wall material dissolves in a solvent system containing DMSO-d6 and NMI-d6, keeping wood component polymers intact and in a near-...

  9. Highly efficient F-19 heteronuclear decoupling in solid-state NMR spectroscopy using supercycled refocused-CW irradiation

    DEFF Research Database (Denmark)

    Equbal, Asif; Basse, Kristoffer; Nielsen, Niels Christian

    2016-01-01

    We present heteronuclear F-19 refocused CW (rCW) decoupling pulse sequences for solid-state magic-angle- spinning NMR applications. The decoupling sequences have been designed specifically to ensure suppression of the pertinent C-13-F-19 dipolar coupling interactions while simultaneously suppress...

  10. Dispersion of Silicate in Tricalcium Phosphate Elucidated by Solid-State NMR

    Energy Technology Data Exchange (ETDEWEB)

    Rewal, A.; Wei, X.; Akinc, M.; Schmidt-Rohr, K.

    2008-03-12

    The dispersion of silicate in tricalcium phosphate, a resorbable bioceramics for bone replacement, has been investigated by various solid-state nuclear magnetic resonance (NMR) methods. In samples prepared with 5 and 10 mol% of both {sup 29}SiO{sub 2} and ZnO, three types of silicate have been detected: (i) SiO{sub 4}{sup 4-} (Q{sub 0} sites) with long longitudinal (T{sub 1,Si}) relaxation times ({approx} 10,000 s), which substitute for {approx}1% of PO{sub 4}{sup 3-}; (ii) silicate nanoinclusions containing Q{sub 2}, Q{sub 1}, and Q{sub 0} sites with T{sub 1,Si} 100 s, which account for most of the silicon; and (iii) crystalline Q{sub 4} (SiO{sub 2}) with long T{sub 1,Si}. Sensitivity was enhanced >100-fold by {sup 29}Si enrichment and refocused detection. The inclusions in both samples have a diameter of {approx}8 nm, as proved by {sup 29}Si{l_brace}{sup 31}P{r_brace} REDOR dephasing on a 30-ms time scale, which was simulated using a multispin approach specifically suited for nanoparticles. {sup 29}Si CODEX NMR with 30-s {sup 29}Si spin diffusion confirms that an inclusion contains >10 Si (consistent with the REDOR result of >100 Si per inclusion). Overlapping signals of silicate Q{sub 2}, Q{sub 1}, and Q{sub 0} sites were spectrally edited based on their J-couplings, using double-quantum filtering. The large inhomogeneous broadening of the Q{sub 2}, Q{sub 1}, and Q{sub 0} {sup 29}Si subspectra indicates that the nanoinclusions are amorphous.

  11. Effect of electrolyte sorbed by nonion-exchange mechanism on the state and diffusive mobility of water and alkali metal ions in perfluorinated sulfocationic membranes from NMR data

    International Nuclear Information System (INIS)

    Volkov, V.I.; Sidorenkova, E.A.; Korochkova, S.A.; Novikov, N.A.; Sokol'skaya, I.B.; Timashev, S.F.

    1994-01-01

    On the basis of data of high-resolution NMR on 1 H nuclei of water, 23 Na and 133 Cs, of counterions Na + and Ca + the influence of nonionexchange sorved alkalis and metal chlorides on the state and diffusive mobility of the counterions was studied. It is shown that the type of co-ion can affect considerably the translational diffusion of metal ions

  12. A Field Study of NMR Logging to Quantify Petroleum Contamination in Subsurface Sediments

    Science.gov (United States)

    Fay, E. L.; Knight, R. J.; Grunewald, E. D.

    2016-12-01

    Nuclear magnetic resonance (NMR) measurements are directly sensitive to hydrogen-bearing fluids including water and petroleum products. NMR logging tools can be used to detect and quantify petroleum hydrocarbon contamination in the sediments surrounding a well or borehole. An advantage of the NMR method is that data can be collected in both cased and uncased holes. In order to estimate the volume of in-situ hydrocarbon, there must be sufficient contrast between either the relaxation times (T2) or the diffusion coefficients (D) of water and the contaminant. In a field study conducted in Pine Ridge, South Dakota, NMR logging measurements were used to investigate an area of hydrocarbon contamination from leaking underground storage tanks. A contaminant sample recovered from a monitoring well at the site was found to be consistent with a mixture of gasoline and diesel fuel. NMR measurements were collected in two PVC-cased monitoring wells; D and T2 measurements were used together to detect and quantify contaminant in the sediments above and below the water table at both of the wells. While the contrast in D between the fluids was found to be inadequate for fluid typing, the T2 contrast between the contaminant and water in silt enabled the estimation of the water and contaminant volumes. This study shows that NMR logging can be used to detect and quantify in-situ contamination, but also highlights the importance of sediment and contaminant properties that lead to a sufficiently large contrast in T2 or D.

  13. Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

    Science.gov (United States)

    Kupka, Teobald; Wieczorek, Piotr P.

    2016-01-01

    In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of 1H and 13C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

  14. NMR studies of sodium cholate-lecithin mixed micelles

    International Nuclear Information System (INIS)

    Eriksson, P.-O.; Lindblom, G.; Arvidson, G.

    1983-01-01

    T 1 and T 2 2 H-NMR relaxation times have been measured for 2 H-labelled phosphatidylcholine in the aqueous solution phase of the ternary system lecithin-sodium cholate-water. In this phase aggregates are formed by a mixture of cholate and lecithin. Information about the dimension of these miscellar aggregates has been obtained from a simple model of the relaxation times in which two modes of molecular motion are considered. The results obtained accord well with recent investigations using laser-light scattering techniques

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

    Science.gov (United States)

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

    2013-10-01

    Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO43-ν1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3-10.3 wt% CO32- range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ν1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals.

  16. Evidence for radiation induced crosslinking in polytetrafluoroethylene by means of high-resolution solid-state 19F high-speed MAS NMR

    International Nuclear Information System (INIS)

    Katoh, Etsuko; Sugisawa, Hisashi; Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao; Yamazaki, Toshimasa

    1999-01-01

    Radiation effects on molecular structure of polytetrafluoroethylene (PTFE) were studied by high-resolution solid-state 19 F high speed magic angle spinning (HS MAS) NMR spectroscopy. Samples used for the NMR studies were prepared by electron beam irradiation of PTFE with a wide range of irradiation doses from 0.5-10 MGy in the molten state at 340 deg. C under oxygen-free atmosphere. While the non-irradiated PTFE displayed only an intense peak of the internal CF 2 , several new signals corresponding to CF 3 , CF 2 and CF groups were observed for the PTFE which was high temperature irradiated at 340 deg. C in oxygen-free atmosphere (hti-PTFE). Intensities of these new signals increased with an increase of irradiation dose. The present solid-state 19 F HS MAS NMR studies provide not only the first experimental evidence regarding the existence of crosslinking structure in hti-PTFE, directly detected as the CF signal, but also the crosslinking density which can be estimated from a proportion of the CF versus total fluorine signal intensities. The higher the irradiation dose, the higher the crosslinking density; hti-PTFE with 10 MGy contains one crosslinking site per approximately 24 CF 2 groups, while the hti-PTFE with 5 MGy contains one crosslinking site per approximately 36 CF 2 groups. Further, G value of crosslinking (G(x)) was estimated from the signal intensities of 19 F HS MAS NMR spectra. The highest G(x)-value, 1.85, was observed for the 2MGy hti-PTFE sample, suggesting that crosslinking of PTFE is formed most efficaciously with 2 MGy irradiation in the molten state at 340 deg. C under oxygen-free atmosphere

  17. Measurement of 14N quadrupole couplings in biomolecular solids using indirect-detection 14N solid-state NMR with DNP.

    Science.gov (United States)

    Jarvis, J A; Haies, I; Lelli, M; Rossini, A J; Kuprov, I; Carravetta, M; Williamson, P T F

    2017-11-07

    The quadrupolar interaction experienced by the spin-1 14 N nucleus is known to be extremely sensitive to local structure and dynamics. Furthermore, the 14 N isotope is 99.6% naturally abundant, making it an attractive target for characterisation of nitrogen-rich biological molecules by solid-state NMR. In this study, dynamic nuclear polarization (DNP) is used in conjunction with indirect 14 N detected solid-state NMR experiments to simultaneously characterise the quadrupolar interaction at multiple 14 N sites in the backbone of the microcrystalline protein, GB3. Considerable variation in the quadrupolar interaction (>700 kHz) is observed throughout the protein backbone. The distribution in quadrupolar interactions observed reports on the variation in local backbone conformation and subtle differences in hydrogen-bonding; demonstrating a new route to the structural and dynamic analysis of biomolecules.

  18. Characterizing the Secondary Protein Structure of Black Widow Dragline Silk Using Solid-State NMR & X-ray Diffraction

    Science.gov (United States)

    Jenkins, Janelle E.; Sampath, Sujatha; Butler, Emily; Kim, Jihyun; Henning, Robert W.; Holland, Gregory P.; Yarger, Jeffery L.

    2013-01-01

    This study provides a detailed secondary structural characterization of major ampullate dragline silk from Latrodectus hesperus (black widow) spiders. X-ray diffraction results show that the structure of black widow major ampullate silk fibers is comprised of stacked β-sheet nanocrystallites oriented parallel to the fiber axis and an amorphous region with oriented (anisotropic) and isotropic components. The combination of two-dimensional (2D) 13C-13C through-space and through-bond solid-state NMR experiments provide chemical shifts that are used to determine detailed information about amino acid motif secondary structure in black widow spider dragline silk. Individual amino acids are incorporated into different repetitive motifs that make up the majority of this protein-based biopolymer. From the solid-state NMR measurements, we assign distinct secondary conformations to each repetitive amino acid motif and hence to the amino acids that make up the motifs. Specifically, alanine is incorporated in β-sheet (poly(Alan) and poly(Gly-Ala)), 31-helix (poly(Gly-Gly-Xaa), and α-helix (poly(Gln-Gln-Ala-Tyr)) components. Glycine is determined to be in β-sheet (poly(Gly-Ala)) and 31-helical (poly(Gly-Gly-Xaa)) regions, while serine is present in β-sheet (poly(Gly-Ala-Ser)), 31-helix (poly(Gly-Gly-Ser)), and β-turn (poly(Gly-Pro-Ser)) structures. These various motif-specific secondary structural elements are quantitatively correlated to the primary amino acid sequence of major ampullate spidroin 1 and 2 (MaSp1 and MaSp2) and are shown to form a self-consistent model for black widow dragline silk. PMID:24024617

  19. N-15 NMR study of the immobilization of 2,4- and 2,6-dinitrotoluene in aerobic compost

    Science.gov (United States)

    Thorn, K.A.; Pennington, J.C.; Kennedy, K.R.; Cox, L.G.; Hayes, C.A.; Porter, B.E.

    2008-01-01

    Large-scale aerobic windrow composting has been used to bioremediate washout lagoon soils contaminated with the explosives TNT (2,4,6- trinitrotoluene) and RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) at several sites within the United States. We previously used 15N NMR to investigate the reduction and binding of T15NT in aerobic bench -scale reactors simulating the conditions of windrow composting. These studies have been extended to 2,4-dinitrotoluene (2,4DNT) and 2,6-dinitrotoluene (2,6DNT), which, as impurities in TNT, are usually present wherever soils have been contaminated with TNT. Liquid-state 15N NMR analyses of laboratory reactions between 4-methyl-3-nitroaniline-15N, the major monoamine reduction product of 2,4DNT, and the Elliot soil humic acid, both in the presence and absence of horseradish peroxidase, indicated that the amine underwent covalent binding with quinone and other carbonyl groups in the soil humic acid to form both heterocyclic and non-heterocyclic condensation products. Liquid-state 15N NMR analyses of the methanol extracts of 20 day aerobic bench-scale composts of 2,4-di-15N-nitrotoluene and 2,6-di-15N-nitrotoluene revealed the presence of nitrite and monoamine, but not diamine, reduction products, indicating the occurrence of both dioxygenase enzyme and reductive degradation pathways. Solid-state CP/MAS 15N NMR analyses of the whole composts, however, suggested that reduction to monoamines followed by covalent binding of the amines to organic matter was the predominant pathway. ?? 2008 American Chemical Society.

  20. 31P-NMR studies on perfused mouse liver

    International Nuclear Information System (INIS)

    McLaughlin, A.C.; Takeda, H.; Chance, B.

    1978-01-01

    From a metabolic viewpoint, the most important organ in the body is the liver. In contrast to more specialized organs such as heart and kidney which perform only one major function, the liver performs a number of major metabolic functions. Two of the most important functions are the catabolism and storage of foodstuffs (in the form of glycogen) and the control of most of the constituents of the blood (in particular, the blood glucose level). Most of these functions are localized within a single type of cell. One way that the liver is able to regulate these diverse reactions is by the control of the ATP level in the cell. Encouraged by the recent success of many groups in using 31 P-NMR to provide a continuous and non-destructive monitor of ATP levels in isolated cells, skeletal muscle, and perfused organs such as heart and kidney, 31 P-NMR was used to investigate ATP levels in perfused liver of mice

  1. Positional isotope exchange studies on enzyme using NMR spectroscopy

    International Nuclear Information System (INIS)

    Matsunaga, T.O.

    1987-01-01

    The isotopically enriched compounds, 18 O-β,γ-ATP and 18 O bridge-labeled pyrophosphate, synthesized previously in this laboratory, were used to investigate and measure the exchange vs. turnover of substrates and products from their central complexes in four selected enzyme systems. Using hi-field 31 P NMR, we were able to differentiate between 18 O labeled in the bridge vs. the non-bridge positions by virtue of the isotope shift upon the phosphorus nuclei. The bridge to non-bridge scrambling of the label was quantitated and the exchange vs. turnover ratios under a variety of conditions was determined. Using the substrate inhibitor carboxycreatinine, PIX experiments with 18 O-β,γ-ATP and creatine kinase were conducted. It was shown that carboxycreatinine and creatine kinase promoted exchange of the 18 O label as determined by NMR. We have concluded that carboxycreatinine is either a substrate that catalyzes very slow turnover or it catalyzes exchange by a dissociative (SN 1 /sub P/) type of mechanism

  2. NMR study of CeTe at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hinderer, J. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)]. E-mail: hinderer@phys.ethz.ch; Weyeneth, S.M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Weller, M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Gavilano, J.L. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Felder, E. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Hulliger, F. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Ott, H.R. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)

    2006-05-01

    We present {sup 125}Te NMR measurements on CeTe powder at temperatures between 1 and 150K and in magnetic fields between 5 and 8T. CeTe is a rocksalt-type intermetallic compound. It orders antiferromagnetically at T{sub N}{approx}2.2K with a much reduced ordered moment [H.R. Ott, J.K. Kjems, F. Hulliger, Phys. Rev. Lett. 42 20 (1979) 1378]. From our low-temperature NMR spectra we infer the presence of at least three inequivalent Te sites at low temperatures. Considering the crystal structure this result is completely unexpected. The linewidths and the Knight shifts of the individual lines are significantly different and increase substantially with decreasing temperature. They follow the temperature dependence of the magnetic susceptibility above 20K. Above T{sub N}, hyperfine fields of 1.6, 0.8 and 0.0T at the three Te sites per Bohr magneton of Ce moment are deduced from Knight shift vs. magnetic susceptibility data. These values are typical for transferred hyperfine fields via conduction electrons.

  3. {sup 77}Se NMR study of nonmagnetic-magnetic transition in (TMTSF){sub 2}X

    Energy Technology Data Exchange (ETDEWEB)

    Mito, T., E-mail: mito_takeshi@hotmail.co [Graduate School of Material Science, University of Hyogo, Hyogo 678-1297 (Japan); Nishiyama, K.; Koyama, T.; Ueda, K.; Kohara, T.; Takeuchi, K.; Akutsu, H.; Yamada, J. [Graduate School of Material Science, University of Hyogo, Hyogo 678-1297 (Japan); Kornilov, A.; Pudalov, V.M. [P.N. Lebedev Physics Institute, Moscow 119991 (Russian Federation); Qualls, J.S. [Sonoma State University, Rohnert Park, CA 94928 (United States)

    2010-12-15

    {sup 77}Se NMR measurements have been carried out on (TMTSF){sub 2}X (X = PF{sub 6} and AsF{sub 6}) single crystals. For both compounds, NMR lines split into double-peaked spectra in the SDW state, which is explained with sinusoidal internal field at Se nucleus positions having the same incommensurate wave number with that of the SDW order. No change in the lineshape was observed at T{sub x} at which the spin-relaxation rate shows a kink, suggesting that this anomaly does not cause significant static changes in internal field at the Se-site.

  4. Postprandial metabolomics: A pilot mass spectrometry and NMR study of the human plasma metabolome in response to a challenge meal

    International Nuclear Information System (INIS)

    Karimpour, Masoumeh; Surowiec, Izabella; Wu, Junfang; Gouveia-Figueira, Sandra; Pinto, Rui; Trygg, Johan; Zivkovic, Angela M.; Nording, Malin L.

    2016-01-01

    The study of postprandial metabolism is relevant for understanding metabolic diseases and characterizing personal responses to diet. We combined three analytical platforms – gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) – to validate a multi-platform approach for characterizing individual variation in the postprandial state. We analyzed the postprandial plasma metabolome by introducing, at three occasions, meal challenges on a usual diet, and 1.5 years later, on a modified background diet. The postprandial response was stable over time and largely independent of the background diet as revealed by all three analytical platforms. Coverage of the metabolome between NMR and GC-MS included more polar metabolites detectable only by NMR and more hydrophobic compounds detected by GC-MS. The variability across three separate testing occasions among the identified metabolites was in the range of 1.1–86% for GC-MS and 0.9–42% for NMR in the fasting state at baseline. For the LC-MS analysis, the coefficients of variation of the detected compounds in the fasting state at baseline were in the range of 2–97% for the positive and 4–69% for the negative mode. Multivariate analysis (MVA) of metabolites detected with GC-MS revealed that for both background diets, levels of postprandial amino acids and sugars increased whereas those of fatty acids decreased at 0.5 h after the meal was consumed, reflecting the expected response to the challenge meal. MVA of NMR data revealed increasing postprandial levels of amino acids and other organic acids together with decreasing levels of acetoacetate and 3-hydroxybutanoic acid, also independent of the background diet. Together these data show that the postprandial response to the same challenge meal was stable even though it was tested 1.5 years apart, and that it was largely independent of background diet. This work demonstrates the efficacy of a

  5. Postprandial metabolomics: A pilot mass spectrometry and NMR study of the human plasma metabolome in response to a challenge meal

    Energy Technology Data Exchange (ETDEWEB)

    Karimpour, Masoumeh; Surowiec, Izabella; Wu, Junfang [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Gouveia-Figueira, Sandra [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå (Sweden); Pinto, Rui [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Bioinformatics Infrastructure for Life Sciences (Sweden); Trygg, Johan [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Zivkovic, Angela M. [Department of Nutrition, University of California, Davis, One Shields Ave, CA 95616 (United States); Nording, Malin L., E-mail: malin.nording@umu.se [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden)

    2016-02-18

    The study of postprandial metabolism is relevant for understanding metabolic diseases and characterizing personal responses to diet. We combined three analytical platforms – gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) – to validate a multi-platform approach for characterizing individual variation in the postprandial state. We analyzed the postprandial plasma metabolome by introducing, at three occasions, meal challenges on a usual diet, and 1.5 years later, on a modified background diet. The postprandial response was stable over time and largely independent of the background diet as revealed by all three analytical platforms. Coverage of the metabolome between NMR and GC-MS included more polar metabolites detectable only by NMR and more hydrophobic compounds detected by GC-MS. The variability across three separate testing occasions among the identified metabolites was in the range of 1.1–86% for GC-MS and 0.9–42% for NMR in the fasting state at baseline. For the LC-MS analysis, the coefficients of variation of the detected compounds in the fasting state at baseline were in the range of 2–97% for the positive and 4–69% for the negative mode. Multivariate analysis (MVA) of metabolites detected with GC-MS revealed that for both background diets, levels of postprandial amino acids and sugars increased whereas those of fatty acids decreased at 0.5 h after the meal was consumed, reflecting the expected response to the challenge meal. MVA of NMR data revealed increasing postprandial levels of amino acids and other organic acids together with decreasing levels of acetoacetate and 3-hydroxybutanoic acid, also independent of the background diet. Together these data show that the postprandial response to the same challenge meal was stable even though it was tested 1.5 years apart, and that it was largely independent of background diet. This work demonstrates the efficacy of a

  6. Investigation into state of phosphomolybdovanadic heteropolyacids in aqueous solutions by the NMR method

    International Nuclear Information System (INIS)

    Maksimovskaya, R.I.; Fedotov, M.A.; Mastikhin, V.M.; Kuznetsova, L.I.; Matveev, K.I.

    1978-01-01

    The methods of 31 P, 51 V, and 17 O NMR have been used for studying the solutions of phospho-molybdenum-vanadium heteropolyacids (HPA) with x=0,1,2,3 (HPA-x) and their mixture with changing concentration, acidity, temperature, and upon partial reduction for separating the lines corresponding to HPA with a certain x. It has been found that in aqueous solutions HPA is present as a mixture of HPA of different compositions; the relationship has been observed between chemical shifts of the lines and the solution acidity which is of a different character for HPA with different x. This allows to make a conclusion about the mechanism of HPA protonation

  7. Error characterization and quantum control benchmarking in liquid state NMR using quantum information processing techniques

    Science.gov (United States)

    Laforest, Martin

    single and multi qubit systems. Even though liquid state NMR is argued to be unsuitable for scalable quantum information processing, it remains the best test-bed system to experimentally implement, verify and develop protocols aimed at increasing the control over general quantum information processors. For this reason, all the protocols described in this thesis have been implemented in liquid state NMR, which then led to further development of control and analysis techniques.

  8. Sensitivity and Resolution Enhanced Solid-State NMR for Paramagnetic Systems and Biomolecules under Very Fast Magic Angle Spinning

    KAUST Repository

    Parthasarathy, Sudhakar

    2013-09-17

    Recent research in fast magic angle spinning (MAS) methods has drastically improved the resolution and sensitivity of NMR spectroscopy of biomolecules and materials in solids. In this Account, we summarize recent and ongoing developments in this area by presenting (13)C and (1)H solid-state NMR (SSNMR) studies on paramagnetic systems and biomolecules under fast MAS from our laboratories. First, we describe how very fast MAS (VFMAS) at the spinning speed of at least 20 kHz allows us to overcome major difficulties in (1)H and (13)C high-resolution SSNMR of paramagnetic systems. As a result, we can enhance both sensitivity and resolution by up to a few orders of magnitude. Using fast recycling (∼ms/scan) with short (1)H T1 values, we can perform (1)H SSNMR microanalysis of paramagnetic systems on the microgram scale with greatly improved sensitivity over that observed for diamagnetic systems. Second, we discuss how VFMAS at a spinning speed greater than ∼40 kHz can enhance the sensitivity and resolution of (13)C biomolecular SSNMR measurements. Low-power (1)H decoupling schemes under VFMAS offer excellent spectral resolution for (13)C SSNMR by nominal (1)H RF irradiation at ∼10 kHz. By combining the VFMAS approach with enhanced (1)H T1 relaxation by paramagnetic doping, we can achieve extremely fast recycling in modern biomolecular SSNMR experiments. Experiments with (13)C-labeled ubiquitin doped with 10 mM Cu-EDTA demonstrate how effectively this new approach, called paramagnetic assisted condensed data collection (PACC), enhances the sensitivity. Lastly, we examine (13)C SSNMR measurements for biomolecules under faster MAS at a higher field. Our preliminary (13)C SSNMR data of Aβ amyloid fibrils and GB1 microcrystals acquired at (1)H NMR frequencies of 750-800 MHz suggest that the combined use of the PACC approach and ultrahigh fields could allow for routine multidimensional SSNMR analyses of proteins at the 50-200 nmol level. Also, we briefly discuss the

  9. Synthetic routes to a nanoscale inorganic cluster [Ga13(μ3-OH)6(μ2-OH)18(H2O)](NO3)15 evaluated by solid-state 71Ga NMR

    International Nuclear Information System (INIS)

    Hammann, Blake A.; Marsh, David A.; Ma, Zayd L.; Wood, Suzannah R.; Eric West, Michael; Johnson, Darren W.; Hayes, Sophia E.

    2016-01-01

    Solid-state 71 Ga NMR was used to characterize a series of [Ga 13 (μ 3 -OH) 6 (μ 2 -OH) 18 (H 2 O)](NO 3 ) 15 “Ga 13 ” molecular clusters synthesized by multiple methods. These molecular clusters are precursors to thin film electronics and may be employed in energy applications. The synthetic routes provide varying levels of impurities in the solid phase, and these impurities often elude traditional characterization techniques such as powder X-ray diffraction and Raman spectroscopy. Solid-state NMR can provide a window into the gallium species even in amorphous phases. This information is vital in order to prevent the impurities from causing defect sites in the corresponding thin films upon gelation and condensation (polymerization) of the Ga 13 clusters. This work demonstrates the resolving power of solid-state NMR to evaluate structure and synthetic quality in the solid state, and the application of high-field NMR to study quadrupolar species, such as 71 Ga. - Graphical abstract: The various synthetic routes and 71 Ga solid-state NMR spectra of the nanoscale inorganic cluster [Ga 13 (μ 3 -OH) 6 (μ 2 -OH) 18 (H 2 O)](NO 3 ) 15 . - Highlights: • Solid-state 71 Ga NMR of hydroxo-aquo metal clusters and the impurities present. • High-field NMR capability allows for quadrupolar species, such as 71 Ga, to be routinely studied. • Efficient and environmentally friendly synthetic routes have been developed to prepare hydroxo-aquo metal clusters.

  10. NMR studies of structures of lanthanide dicarboxylate complexes in solution

    International Nuclear Information System (INIS)

    Choppin, G.R.; Kullberg, L.

    PMR pand 13 C shift data were measured for complexes of Pr(III), Eu(III) and Yb(III) with ethylene 1,2-dioxydiacetate (EDODA), ethylene 1,2-dithiodiacetate (EDSDA), and ethylene, 1,2-diaminodiacetate (EDDA). Solubility problems limited analysis of the EDSDA and EDDA data to qualitative evaluation. In the EDSDA complexes, the data indicate that the sulfur atoms do not participate in bonding to the lanthanide cations. Moreover, both carboxylate groups seem to bind Pr and Eu while Yb interacts with only a single carboxylate group. The EDDA complexes are tetradentate with long lived (NMR scale) Ln-N bonds. Shift theory allowed more quantitative analysis of the EDODA complexes. They are tetradentate with a puckered chelate ring and Ln-O(ether) distances of 2.3 A

  11. 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.

  12. Tannin fingerprinting in vegetable tanned leather by solid state NMR spectroscopy and comparison with leathers tanned by other processes.

    Science.gov (United States)

    Romer, Frederik H; Underwood, Andrew P; Senekal, Nadine D; Bonnet, Susan L; Duer, Melinda J; Reid, David G; van der Westhuizen, Jan H

    2011-01-28

    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.

  13. Proton and deuteron NMR study of PTFE ionomer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, G; Pak, Y S [Dept. of Materials Science, McMaster Univ., Hamilton, Ontario (Canada)

    1992-02-01

    Proton and deuteron NMR have been conducted to investigate the ionic motion in perfluorinated ionomer membranes from Dow Chemical (XUS) and DuPont (Nafion{sup R}). Two proton relaxation peaks were found in the XUS specimen absorbed with H{sub 2}O. The major (narrow) peak presented a spin-lattice relaxation time (T{sub 1}) of 107 ms while the minor (broader) one gave much longer T{sub 1}. While the former was attributed to the water molecules involved in restricted motion, the latter was expected to be associated with the protons located in the vicinity of the sulfonate groups. Similar to the previous results from the others, only a single peak was detected in Nafion{sup R} in {sup 1}H spectra, indicating that the protons in the different environments were engaging rapid exchange within NMR time scale. In contrast to the inverse proportion dependence of the linewidth on the water sorption in Nafion{sup R}, the major line of the XUS membrane exhibited insensitive linewidth dependence on the variation of H{sub 2}O concentration. The difference was attributed to the existence of narrow breaths of the pores in XUS sample, such that free water contribution to the enhancement of proton mobility was limited. The {sup 2}H spectra of Nafion{sup R} were found to possess a doublet, due to nuclear quadrupolar interaction. Dow (XUS) membrane treated in at 100% relative humidity (RH) D{sub 2}O presented a single peak with the linewidth insensitive to the amount of heavy water absorbed. An additional rise emerged on the ''shoulder'' of this single peak when treated at 33% RH. It is concluded that XUS membrane does not provide strong hydrogen bonding to eliminate the rapid motion average over the nuclear quadrupole interaction. (orig.).

  14. Structural Studies of Bcl-xL/ligand Complexes using {sup 19}F NMR

    Energy Technology Data Exchange (ETDEWEB)

    Yu Liping; Hajduk, Philip J.; Mack, Jamey; Olejniczak, Edward T. [GPRD, Abbott Laboratories, Pharmaceutical Discovery Division (United States)], E-mail: Edward.olejniczak@abbott.com

    2006-04-15

    Fluorine atoms are often incorporated into drug molecules as part of the lead optimization process in order to improve affinity or modify undesirable metabolic and pharmacokinetic profiles. From an NMR perspective, the abundance of fluorinated drug leads provides an exploitable niche for structural studies using {sup 19}F NMR in the drug discovery process. As {sup 19}F has no interfering background signal from biological sources, {sup 19}F NMR studies of fluorinated drugs bound to their protein receptors can yield easily interpretable and unambiguous structural constraints. {sup 19}F can also be selectively incorporated into proteins to obtain additional constraints for structural studies. Despite these advantages, {sup 19}F NMR has rarely been exploited for structural studies due to its broad lines in macromolecules and their ligand complexes, leading to weak signals in {sup 1}H/{sup 19}F heteronuclear NOE experiments. Here we demonstrate several different experimental strategies that use {sup 19}F NMR to obtain ligand-protein structural constraints for ligands bound to the anti-apoptotic protein Bcl-xL, a drug target for anti-cancer therapy. These examples indicate the applicability of these methods to typical structural problems encountered in the drug development process.

  15. Gravity-driven pH adjustment for site-specific protein pKa measurement by solution-state NMR

    Science.gov (United States)

    Li, Wei

    2017-12-01

    To automate pH adjustment in site-specific protein pKa measurement by solution-state NMR, I present a funnel with two caps for the standard 5 mm NMR tube. The novelty of this simple-to-build and inexpensive apparatus is that it allows automatic gravity-driven pH adjustment within the magnet, and consequently results in a fully automated NMR-monitored pH titration without any hardware modification on the NMR spectrometer.

  16. The pH behavior of a 2-aminoethyl dihydrogen phosphate zwitterion studied with NMR-titrations

    Science.gov (United States)

    Myller, A. T.; Karhe, J. J.; Haukka, M.; Pakkanen, T. T.

    2013-02-01

    In this study a bifunctional 2-aminoethyl dihydrogen phosphate (AEPH2) was 1H and 31P NMR characterized in a pH range of 1-12 in order to determine the zwitterion properties in different pH regions in H2O and D2O solutions. NMR was also used to determine the pH range where AEPH2 exists as a zwitterion. The phosphate group has two deprotonation points, around pH 1 and 6, while the amino group deprotonates at pH 11. The zwitterion form of AEPH2 (NH3+sbnd CHsbnd CHsbnd OPOH) exists as the main ion between pH 1 and 6 in water solutions and also in the solid state.

  17. Selective and extensive 13C labeling of a membrane protein for solid-state NMR investigations

    International Nuclear Information System (INIS)

    Hong, M.; Jakes, K.

    1999-01-01

    The selective and extensive 13C labeling of mostly hydrophobic amino acid residues in a 25 kDa membrane protein, the colicin Ia channel domain, is reported. The novel 13C labeling approach takes advantage of the amino acid biosynthetic pathways in bacteria and suppresses the synthesis of the amino acid products of the citric acid cycle. The selectivity and extensiveness of labeling significantly simplify the solid-state NMR spectra, reduce line broadening, and should permit the simultaneous measurement of multiple structural constraints. We show the assignment of most 13C resonances to specific amino acid types based on the characteristic chemical shifts, the 13C labeling pattern, and the amino acid composition of the protein. The assignment is partly confirmed by a 2D homonuclear double-quantum-filter experiment under magic-angle spinning. The high sensitivity and spectral resolution attained with this 13C-labeling protocol, which is termed TEASE for ten-amino acid selective and extensive labeling, are demonstrated

  18. Delineating pMDI model reactions with loblolly pine via solution-state NMR spectroscopy. Part 2, Non-catalyzed reactions with the wood cell wall

    Science.gov (United States)

    Daniel J. Yelle; John Ralph; Charles R. Frihart

    2011-01-01

    Solution-state NMR provides a powerful tool to observe the presence or absence of covalent bonds between wood and adhesives. Finely ground wood can be dissolved in an NMR compatible solvent system containing dimethylsulfoxide-d6 and N-methylimidazole-d6, in which the wood polymers remain largely intact. High-resolution...

  19. Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

    International Nuclear Information System (INIS)

    Rivas Mercury, J.M.; Pena, P.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

    2007-01-01

    Partially deuterated Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x hydrates prepared by a reaction in the presence of D 2 O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29 Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x was followed by 27 Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 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

  20. Unusual spin frozen state in a frustrated pyrochlore system NaCaCo{sub 2}F{sub 7} as observed by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, R.; Brueckner, F.; Klauss, H.H. [IFP, TU Dresden (Germany); Krizan, J.W.; Cava, R.J. [Department of Chemistry, Princeton University, Princeton, NJ (United States)

    2016-07-01

    We present {sup 23}Na -and {sup 19}F NMR results on the magnetically frustrated pyrochlore NaCaCo{sub 2}F{sub 7} with a frustration index of f = θ{sub CW}/T{sub f} ∝ 56. Recent neutron scattering experiments proposed XY like antiferromagnetic spin clusters at low energies in NaCaCo{sub 2}F{sub 7}. {sup 23}Na NMR -spectra reveal the presence of two magnetically non equivalent Na sites in conjunction with the local Co{sup 2+} spin structure. Below 3.6 K both the {sup 23}Na -and {sup 19}F spectra broaden due to the formation of static spin correlations. A huge reduction of the {sup 19}F -and {sup 23}Na NMR signal intensity hints at a quasi-static field distribution in NaCaCo{sub 2}F{sub 7} in this regime. The {sup 19}F spin-lattice relaxation rate {sup 19}(1/T{sub 1}) exhibits a peak at around 2.9 K, at the same temperature range where ac and dc susceptibility data show a broad maximum. The character of the spin fluctuation appears to be isotropic. The overall temperature dependence of {sup 19}(1/T{sub 1}) can be described by the BPP theory considering a fluctuating hyperfine field with an autocorrelation function. The correlation time of the autocorrelation function exhibits an activation behavior further indicating the spin-frozen state. While the present NMR studies suggest the spin frozen state at low temperatures, μSR investigations however reveal the presence of so called persistent spin dynamics down to 20 mK implying an exotic ground state in NaCaCo{sub 2}F{sub 7}.

  1. 1H Nuclear Magnetic Resonance (NMR) metabonomic study of breast cancer in Indian population

    International Nuclear Information System (INIS)

    Sonkar, Kanchan; Sinha, Neeraj; Arshad, Farah

    2012-01-01

    Breast cancer is the most common cancer diagnosed in women worldwide with over 1.3 million new cases per year. Recently it has been observed that breast cancer is increasing very rapidly in low income countries including India. Lipids not only play very important and vital role of prime structural component in human body they are also important functional components in cellular metabolism. Transformation from benign to malignant tissue involves several biochemical processes and understanding these processes provides very useful insight related to cancer prognosis. Thus study of lipids becomes very important and NMR spectroscopy is one of the techniques which can be utilized to identifying all lipid components simultaneously. The tissue specimens (35, benign 20 and malignant 15; patient age group 47 yrs) were collected after breast surgeries and were snap frozen in liquid nitrogen. Part of all tissues was sent for routine histopathology. Lipid extraction was performed by Folch method (Folch, 1957) using cholesterol and methanol (2:1 ratio). The NMR spectra of the extracted lipids were recorded immediately after the sample preparation. All NMR experiments were performed on a Bruker Avance 800 MHz spectrometer. 1 H NMR analysis of lipid extract of breast tissue in Indian population shows there is significant elevation of phosphotidycholine, plasmalogen and esterified cholesterol with decrease in triacylglycerol in cancer breast compared to benign tissue implying that their metabolism is definitely altered during carcinogenesis. This study analyzes the role of NMR as an additional diagnostic tool on the basis of examination of lipid extract. (author)

  2. NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes.

    Science.gov (United States)

    Adam, Christian; Beele, Björn B; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J

    2015-02-01

    C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15 N labeling and characterized by NMR and LIFDI-MS methods. 15 N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15 N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP) 3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP) 3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.

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

    Science.gov (United States)

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

    2018-02-01

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

  4. NMR/NQR study of the superconductor Y2Ba4Cu7O15

    International Nuclear Information System (INIS)

    Stern, R.

    1995-01-01

    This dissertation concentrates on several important aspects of the high temperature superconductivity research. Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies in Y-Ba-O compounds contribute information regarding various aspects, ranging from the direct observation of strong coupling between the adjacent planes in the double plane to conclusions concerning the spatial symmetry of paring state in these cuprates. We report the first results in the 93 K superconductor Y 2 Ba 4 Cu 7 O 15 . This compound turns out to be a structure containing differently doped CuO 2 planes. The planes in the 1-2-3(1-2-4) block are only slightly lower (higher) doped than those in the corresponding parent compounds YBa 2 Cu 3 O 7 and YBa 2 Cu 4 O 8 . The results obtained from measurements on oxygen depleted Y 2 Ba 4 Cu 7 O 15-x show two new features which could explain the dissimilar variation of T c with oxygen content compared to YBa 2 Cu 3 O 7-x : i) the double chains donate charge carriers to the planes and ii) the chain fragments which survive when emptying single chains are longer than in YBa 2 Cu 3 O 7-x . The pressure induced charge transfer from chain to plane in each block of Y 2 Ba 4 Cu 7 O 15 is the same as in the corresponding parent compound. We explore the strong coupling between nonequivalent planes in this compound using the three main NMR/NQR quantities, K spin , 1/T 1 ; and T 2G,ind , and estimate its approximate strength directly from spin-echo double resonance (SEDOR) experiments. We obtain for the ratio of the effective inter- and intraplane exchange-coupling constants the value of 0.3 just above T c . This ratio decreases with increasing temperature. (author) figs., tabs., refs

  5. Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin.

    Science.gov (United States)

    Wałęsa, Roksana; Ptak, Tomasz; Siodłak, Dawid; Kupka, Teobald; Broda, Małgorzata A

    2014-06-01

    The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by (1)H and (13)C NMR. Six complexes EYL-Ac-Phe-NHMe, stabilized by N-H···O or/and C-H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar 'head' of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in phosphate group that acts as proton acceptor. Copyright © 2014 John Wiley & Sons, Ltd.

  6. On-Going Bentonite Pore Water Studies by NMR and SAXS

    International Nuclear Information System (INIS)

    Carlsson, Torbjoern; Muurinen, Arto; Root, Andrew

    2013-01-01

    Compacted water-saturated MX-80 bentonite is presently being studied by SAXS and NMR in order to quantify the major pore water phases in the bentonite. The SAXS and NMR measurements gave very similar results indicating that the pore water is mainly distributed between two major phases (interlayer and non-interlayer water) and also indicate how these phases depend on the bentonite dry density. The results from the SAXS and NMR studies at VTT indicate the same thing: - The pore water in water-saturated compacted (?dry = 0.7-1.6 g/cm 3 ) bentonite is divided into two main phases: interlayer water and non-interlayer water. - The amounts of these pore water phases can be determined quantitatively with the above methods. (authors)

  7. NMR relaxometry study of plaster mortar with polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Jumate, E.; Manea, D. [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania); Moldovan, D.; Fechete, R. [Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca (Romania)

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

  8. NMR relaxometry study of plaster mortar with polymer additives

    Science.gov (United States)

    Jumate, E.; Moldovan, D.; Fechete, R.; Manea, D.

    2013-11-01

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T2 relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T2 distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T2 relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T2 relaxation rates corresponding to the bound water.

  9. NMR relaxometry study of plaster mortar with polymer additives

    International Nuclear Information System (INIS)

    Jumate, E.; Manea, D.; Moldovan, D.; Fechete, R.

    2013-01-01

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T 2 relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T 2 distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T 2 relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T 2 relaxation rates corresponding to the bound water

  10. Xenon-Water Interaction in Bacterial Suspensions as Studied by NMR

    DEFF Research Database (Denmark)

    Rodin, V.; Ponomarev, Alexander; Gerasimov, Maxim

    2017-01-01

    suspensions of Escherichia coli in the presence of xenon using nuclear magnetic resonance (NMR). The work studied how the spin-lattice relaxation times of water protons in suspension change under xenon conditions. Xenon is able to form clathrate hydrates with water molecules at a temperature above the melting...... point of ice. The work studied NMR relaxation times which reflect the rotation freedom of water molecules in suspension. Lower relaxation times indicate reduced rotational freedom of water. Single exponential behavior of spin-lattice relaxation of protons in the suspensions of microorganisms has been...

  11. Synergistic Applications of MD and NMR for the Study of Biological Systems

    Directory of Open Access Journals (Sweden)

    Olivier Fisette

    2012-01-01

    same time, theoretical and computational approaches gain in reliability and their field of application widens. In this short paper, we discuss recent advances in the areas of solution nuclear magnetic resonance (NMR spectroscopy and molecular dynamics (MD simulations that were made possible by the combination of both methods, that is, through their synergistic use. We present the main NMR observables and parameters that can be computed from simulations, and how they are used in a variety of complementary applications, including dynamics studies, model-free analysis, force field validation, and structural studies.

  12. Probing hydrogen bonds in the antibody-bound HIV-1 gp120 V3 loop by solid state NMR REDOR measurements

    Energy Technology Data Exchange (ETDEWEB)

    Balbach, John J. [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States); Yang Jun; Weliky, David P. [Michigan State University, Department of Chemistry (United States); Steinbach, Peter J. [National Institutes of Health, Center for Molecular Modeling, Center for Information Technology (United States); Tugarinov, Vitali; Anglister, Jacob [Weizmann Institute of Science, Department of Structural Biology (Israel); Tycko, Robert [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2000-04-15

    We describe solid state NMR measurements on frozen solutions of the complex of the 24-residue HIV-1 gp120 V3 loop peptide RP135 with the Fab fragment of the anti-gp120 antibody 0.5{beta}, using rotational echo double resonance (REDOR). In order to probe possible hydrogen bonding between arginine side chains and glycine backbone carbonyls in the region of the conserved Gly-Pro-Gly-Arg (GPGR) motif of the V3 loop, RP135 samples were prepared with {sup 15}N labels at the {eta} nitrogen positions of arginine side chains and {sup 13}C labels at glycine carbonyl positions and {sup 13}C-detected {sup 13}C-{sup 15}N REDOR measurements were performed on peptide/antibody complexes of these labeled samples. Such hydrogen bonding was previously observed in a crystal structure of the V3 loop peptide/antibody complex RP142/59.1 [Ghiara et al. (1994) Science, 264, 82-85], but is shown by the REDOR measurements to be absent in the RP135/0.5{beta} complex. These results confirm the antibody-dependent conformational differences in the GPGR motif suggested by previously reported solid state NMR measurements of {phi} and {psi} backbone dihedral angles in the RP135/0.5{beta} complex. In addition, we describe REDOR measurements on the helical synthetic peptide MB(i+4)EK in frozen solution that establish our ability to detect {sup 13}C-{sup 15}N dipole-dipole couplings in the distance range appropriate to these hydrogen bonding studies. We also report the results of molecular modeling calculations on the central portion RP135, using a combination of the solid state NMR restraints of Weliky et al. [Nat. Struct. Biol., 6, 141-145, 1999] and the liquid state NMR restraints of Tugarinov et al. (Nat. Struct. Biol., 6, 331-335, 1999]. The dynamics calculations demonstrate the mutual compatibility of the two sets of experimental structural restraints and reduce ambiguities in the solid state NMR restraints that result from symmetry and signal-to-noise considerations.

  13. Probing hydrogen bonds in the antibody-bound HIV-1 gp120 V3 loop by solid state NMR REDOR measurements

    International Nuclear Information System (INIS)

    Balbach, John J.; Yang Jun; Weliky, David P.; Steinbach, Peter J.; Tugarinov, Vitali; Anglister, Jacob; Tycko, Robert

    2000-01-01

    We describe solid state NMR measurements on frozen solutions of the complex of the 24-residue HIV-1 gp120 V3 loop peptide RP135 with the Fab fragment of the anti-gp120 antibody 0.5β, using rotational echo double resonance (REDOR). In order to probe possible hydrogen bonding between arginine side chains and glycine backbone carbonyls in the region of the conserved Gly-Pro-Gly-Arg (GPGR) motif of the V3 loop, RP135 samples were prepared with 15 N labels at the η nitrogen positions of arginine side chains and 13 C labels at glycine carbonyl positions and 13 C-detected 13 C- 15 N REDOR measurements were performed on peptide/antibody complexes of these labeled samples. Such hydrogen bonding was previously observed in a crystal structure of the V3 loop peptide/antibody complex RP142/59.1 [Ghiara et al. (1994) Science, 264, 82-85], but is shown by the REDOR measurements to be absent in the RP135/0.5β complex. These results confirm the antibody-dependent conformational differences in the GPGR motif suggested by previously reported solid state NMR measurements of φ and Ψ backbone dihedral angles in the RP135/0.5β complex. In addition, we describe REDOR measurements on the helical synthetic peptide MB(i+4)EK in frozen solution that establish our ability to detect 13 C- 15 N dipole-dipole couplings in the distance range appropriate to these hydrogen bonding studies. We also report the results of molecular modeling calculations on the central portion RP135, using a combination of the solid state NMR restraints of Weliky et al. [Nat. Struct. Biol., 6, 141-145, 1999] and the liquid state NMR restraints of Tugarinov et al. (Nat. Struct. Biol., 6, 331-335, 1999]. The dynamics calculations demonstrate the mutual compatibility of the two sets of experimental structural restraints and reduce ambiguities in the solid state NMR restraints that result from symmetry and signal-to-noise considerations

  14. 1H-NMR/13C-NMR studies of branched structures in PVC obtained at atmospheric pressure

    International Nuclear Information System (INIS)

    Braun, D.; Holzer, G.; Hjertberg, T.

    1981-01-01

    The 1 H-NMR-spectra of raw poly (vinyl cloride) obtained at atmospheric pressure (U-PVC) have revealed the presence of high concentrations of branches. The content of labile chlorine was determined by reaction with phenole in order to estimate the branch points with tertiary chlorine. The branch length of reductively dehalogenated U-PVC by 13 C-NMR analysis have provided evidence for both short chain branches including chloromethyl groups and 2.4-dichloro-n-butyl groups and long chain branching. For a number of U-polymers the total amount of branching ranges from 7.5 to 13.5/1000 C. The 13 C-NMR measurements point to a ratio of methyl/butyl branches of 1:1 and short chains/long chains of 6:1. (orig.)

  15. 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.

  16. Which kind of aromatic structures are produced during biomass charring? New insights provided by modern solid-state NMR spectroscopy

    Science.gov (United States)

    Knicker, Heike; Paneque-Carmona, Marina; Velasco-Molina, Marta; de la Rosa, José Maria; León-Ovelar, Laura Regina; Fernandez-Boy, Elena

    2017-04-01

    Intense research on biochar and charcoal of the last years has revealed that depending on the production conditions, the chemical and physical characteristics of their aromatic network can greatly vary. Since such variations are determining the behavior and stability of charred material in soils, a better understanding of the structural changes occurring during their heating and the impact of those changes on their function is needed. One method to characterize pyrogenic organic matter (PyOM) represents solid-state 13C NMR spectroscopy applying the cross polarization (CP) magic angle spinning technique (MAS). A drawback of this technique is that the quantification of NMR spectra of samples with highly condensed and proton-depleted structures is assumed to be bias. Typical samples with such attributes are charcoals produced at temperatures above 700°C under pyrolytic conditions. Commonly their high condensation degree leads to graphenic structures that are not only reducing the CP efficiency but create also a conductive lattice which acts as a shield and prevents the entering of the excitation pulse into the sample during the NMR experiments. Since the latter can damage the NMR probe and in the most cases the obtained NMR spectra show only one broad signal assignable to aromatic C, this technique is rarely applied for characterizing high temperature chars or soot. As a consequence, a more detailed knowledge of the nature of the aromatic ring systems is still missing. The latter is also true for the aromatic domains of PyOM produced at lower temperatures, since older NMR instruments operating at low magnetic fields deliver solid-state 13C NMR spectra with low resolution which turns a more detailed analysis of the aromatic chemical shift region into a challenging task. In order to overcome this disadvantages, modern NMR spectroscopy offers not only instruments with greatly improved resolution but also special pulse sequences for NMR experiments which allow a more

  17. Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials

    Science.gov (United States)

    Paik, Younkee

    Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

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

    International Nuclear Information System (INIS)

    Holzmueller, P.

    1992-01-01

    Purpose of this study was to investigate applications of proton nuclear magnetic resonance ( 1 H-NMR) relaxometry in experimental medicine. Relaxometry was performed by measurements of spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation time parameters on liver biopsies up to four hours after biopsy excision. Variations of relaxation times due to species and strain, different sample handling and different liver damage models, ethionine fatty liver and paracetamol liver necrosis, were investigated. Cell integrity effects were studied on homogenized liver samples. Relaxation time parameters, especially 'main' components T 1A and T 2A of biexponential model fit, were identified to react very sensitive after tissue damages as well as to cell viability. Thus, investigation of stored liver grafts was performed in order to evaluate the possibility of a rapid liver graft viability testing method for human liver transplantation surgery by 1 H-NMR relaxometry. Another series of measurements was performed to investigate the applicability of isoflurane anesthesia for in vivo NMR experiments. This study proved the good appropriateness of isoflurane for that purpose provided that physiological monitoring and individual adjustment of anesthesia are performed. In these investigations it could be revealed that mainly T 1A and T 2A are influenced by tissue condition and that different information is inherent in these two parameters, with T 2A reflecting tissue viability and changes of tissue conditions very sensitively but rather unspecifically in respect to the damage applied. Based on these results the following future applications of 1 H-NMR relaxometry are suggested : (1) model investigations, (2) investigation of given pathologies, (3) investigation of basic requirements for in vivo NMR and (4) application in a liver graft viability testing protocol, which seems to be the most important future application of 1 H-NMR relaxometry in medicine. (author)

  19. 31P-NMR study of human pyrimidine 5'-nucleotidase deficient erythrocytes

    International Nuclear Information System (INIS)

    Higaki, Tsuyoshi; Kagimoto, Tadashi; Nagata, Koichi; Tanase, Sumio; Morino, Yoshimasa; Takatsuki, Kiyoshi

    1982-01-01

    Metabolic disorder of nucleotides in human pyrimidine 5'-nucleotidase (P5N) deficient erythrocytes was studied by 31 P-NMR with high resolution. Identification by combination of high-speed liquid chromatography revealed two-fold increases from the normal in the spectra in the α-, β- and γ-zones of nucleoside triphosphates of P5N deficient erythrocytes, 2,3-diphosphoglycerate shifted to the 0.3 ppm low magnetic field and signals of NAD and UDP-sugars(s) in the diphosphodiester zone. These results were obtained from the 31 P-NMR spectrum about one hour after blood sampling, indicating the high utility of this NMR for the diagnosis of P5N deficiency. (Chiba, N.)

  20. Positron annihilation and 129Xe NMR studies of free volume in polymers

    International Nuclear Information System (INIS)

    Nagasaka, Bunsow; Eguchi, Taro; Nakayama, Hirokazu; Nakamura, Nobuo; Ito, Yasuo

    2000-01-01

    The existence and the average size of free volume in bisphenol-A polycarbonate (PC), low-density polyethylene (LDPE), poly (2,6-dimethyl-phenylene oxide)(PPO), and polytetrafluoroethylene (PTFE) were studied by positron annihilation and 129 Xe NMR measurements. The 129 Xe NMR chemical shifts for xenon adsorbed in the polymers indicated that the average pore size of the free volume increased in the following order: PC, LDPE, PPO, and PTFE. This order of the pore size of the free volume agrees well with that estimated from the longest lifetime (τ 3 ) of ortho-positronium formed in the polymers. The unique correlation that δ -1 ∝ r is established between the 129 Xe NMR chemical shift (δ) and the pore size (r), which is deduced from the positron annihilation measurements.

  1. Structural variation study of cobalt nanoparticles synthesized by co-precipitation method using 59Co NMR

    Science.gov (United States)

    Manjunatha, M.; Kumar, Rajeev; B. M., Siddesh; Sahoo, Balaram; Damle, R.; Ramesh, K. P.

    2018-04-01

    We have synthesized cobalt nanoparticles using co-precipitation method. Further, the two phases of the cobalt is monitored by varying the synthesis parameters. 59Co NMR and XRD are used as characterization tools to study the phase variation in the cobalt samples. XRD and NMR results show a remarkable correlation in the two samples (Co-1 and Co-2). Co-2 has predominant fcc and hcp phases, whereas, Co-1 has fcc phase with lower amount of hcp. Both the samples show same saturation magnetization (Ms) but there is a remarkable difference in the phase composition. Thus, 59Co NMR appears to be a good tool to identify the phase purity of the ferromagnetic cobalt samples.

  2. Molecular motion of micellar solutes: a 13C NMR relaxation study

    International Nuclear Information System (INIS)

    Stark, R.E.; Kasakevich, M.L.; Granger, J.W.

    1982-01-01

    A series of simple NMR relaxation experiments have been performed on nitrobenzene and aniline dissolved in the ionic detergents sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB). Using 13 C relaxation rates at various molecular sites, and comparing data obtained in organic media with those for micellar solutions, the viscosity at the solubilization site was estimated and a detailed picture of motional restrictions imposed by the micellar enviroment was derived. Viscosities of 8 to 17 cp indicate a rather fluid environment for solubilized nitrobenzene; both additives exhibit altered motional preferences in CTAB solutions only. As an aid in interpretation of the NMR data, quasi-elastic light scattering and other physical techniques have been used to evaluate the influence of organic solutes on micellar size and shape. The NMR methods are examined critically in terms of their general usefulness for studies of solubilization in detergent micelles. 48 references

  3. 27Al NMR studies of NpPd5Al2

    International Nuclear Information System (INIS)

    Chudo, H.; Sakai, H.; Tokunaga, Y.; Kambe, S.; Aoki, D.; Homma, Y.; Shiokawa, Y.; Haga, Y.; Ikeda, S.; Matsuda, T.D.; Onuki, Y.; Yasuoka, H.

    2009-01-01

    We present 27 Al NMR studies for a single crystal of the Np-based superconductor NpPd 5 Al 2 (T c =4.9K). We have observed a five-line 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 c . The temperature dependence of the 27 Al nuclear spin-lattice relaxation rate shows no coherence peak below T c , indicating that NpPd 5 Al 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 5 Al 2 .

  4. 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...

  5. Paramagnetic relaxation enhancements in NMR peptide-membrane interaction studies

    International Nuclear Information System (INIS)

    Kosol, S.

    2011-01-01

    Small membrane-bound proteins or peptides are involved in numerous essential biological processes, like cellular recognition, signaling, channel formation, and cytolysis. The secondary structure, orientation, mode of interaction and dynamics of these peptides can be as varied as their functions. Their localization in the membrane, the immersion depth, and their binding mode are factors critical to the function of these peptides. The atomic 3D solution structure of peptides bound to micelles can be determined by NMR spectroscopy. However, by employing paramagnetic relaxation enhancements (PREs) information on the complete topology of peptide bound to a micelle can be obtained. The antimicrobial peptide maximin H6, fst, a bacterial toxin, and the human peptide hormone ghrelin served as membrane-bound model peptides of similar sizes but strongly differing amino acid sequences. Their structures and binding behavior were determined and compared.The measured PREs provided suitable data for determining and distinguishing the different topologies of the investigated peptides bound to micelles. Maximin H6 and fst fold into α-helices upon insertion into a membrane, whereas the unstructured ghrelin is freely mobile in solution and interacts only via a covalently bound octanoyl group with the lipids. Maximin H6 is oriented parallel to the membrane surface, enabling the peptide to aggregate at the membrane water interface. Fst binds in transmembrane orientation with a protruding intrinsically disordered region near the C-terminus. Aside from determining the orientation of the bound peptides from the PREs, the moieties critical for membrane binding could be mapped in ghrelin. If suitable relaxation-edited spectra are acquired, the complete orientation and immersion depth of a peptide bound to a micelle can readily be obtained. (author) [de

  6. Conformational dynamics of Escherichia coli flavodoxins in apo- and holo-states by solution NMR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Qian Ye

    Full Text Available Flavodoxins are a family of small FMN-binding proteins that commonly exist in prokaryotes. They utilize a non-covalently bound FMN molecule to act as the redox center during the electron transfer processes in various important biological pathways. Although extensive investigations were performed, detailed molecular mechanisms of cofactor binding and electron transfer remain elusive. Herein we report the solution NMR studies on Escherichia coli flavodoxins FldA and YqcA, belonging to the long-chain and short-chain flavodoxin subfamilies respectively. Our structural studies demonstrate that both proteins show the typical flavodoxin fold, with extensive conformational exchanges observed near the FMN binding pocket in their apo-forms. Cofactor binding significantly stabilizes both proteins as revealed by the extension of secondary structures in the holo-forms, and the overall rigidity shown by the backbone dynamics data. However, the 50 s loops of both proteins in the holo-form still show conformational exchanges on the µs-ms timescales, which appears to be a common feature in the flavodoxin family, and might play an important role in structural fine-tuning during the electron transfer reactions.

  7. Synthesis of deuterium-labeled plant sterols and analysis of their side-chain mobility by solid state deuterium NMR

    International Nuclear Information System (INIS)

    Marsan, M.P.; Muller, I.; Milon, A.

    1996-01-01

    Sitosterol and stigmasterol, plant sterols, were deuterated at specific positions. Orientation and mobility of the deuterated sitosterol and stigmasterol (and two of their diasteromers) on oriented lipid bilayers were analyzed by deuterium NMR spectroscopy. Orientation and mobility of the side chains was revealed by these studies

  8. 53Cr NMR study of CuCrO2 multiferroic

    Science.gov (United States)

    Smol'nikov, A. G.; Ogloblichev, V. V.; Verkhovskii, S. V.; Mikhalev, K. N.; Yakubovskii, A. Yu.; Kumagai, K.; Furukawa, Y.; Sadykov, A. F.; Piskunov, Yu. V.; Gerashchenko, A. P.; Barilo, S. N.; Shiryaev, S. V.

    2015-11-01

    The magnetically ordered phase of the CuCrO2 single crystal has been studied by the nuclear magnetic resonance (NMR) method on 53Cr nuclei in the absence of an external magnetic field. The 53Cr NMR spectrum is observed in the frequency range νres = 61-66 MHz. The shape of the spectrum depends on the delay tdel between pulses in the pulse sequence τπ/2- t del-τπ- t del-echo. The spin-spin and spin-lattice relaxation times have been measured. Components of the electric field gradient, hyperfine fields, and the magnetic moment on chromium atoms have been estimated.

  9. In vivo 7Li and 19F NMR studies of drugs in the brain

    International Nuclear Information System (INIS)

    Komoroski, Richard A.

    1999-01-01

    For various reasons, it is advantageous to measure the concentration of a psychoactive drug in the brain in vivo. Many drugs contain the element fluorine. Using 19 F NMR spectroscopy, we have studied the psychoactive drugs trifluoperazine and fluoxetine in the brain in vivo. Using 7 Li NMR, it is possible to detect lithium ion, used to treat manic depressive illness. We have measured the concentration and distribution of lithium in both human and rat brain in vivo. Measurement of drug levels in the human brain may provide a measure of therapeutic or toxic effects, as well as insight into drug metabolism and mechanism of action. (author)

  10. sup(1)H-NMR study of restricted rotation in dithiophosphoromethyl acetanilides

    International Nuclear Information System (INIS)

    Kovacs, Zs.

    1985-01-01

    sup(1)H-NMR spectra of a series of dithiophosphoromethyl acetanilide derivatives were investigated. The presence of an ortho substituted aryl group bonded to the nitrogen atom of the amide group allowed the observation of restricted internal rotation around the aryl-nitrogen bond. Coalescence temperature and the values of the free energy of activation were determined from the temperature dependent NMR behaviour of these molecules. The possibility of cis-trans isomerism about the nitrogen carbonyl bond was also studied, and the assignment of the conformation of the existing isomer was also made using the aromatic solvent induced shift. (author)

  11. {sup 11}B-NMR spectroscopic study on the interaction of epinephrine and p-BPA

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, K.; Yoshino, K. [Shinshu Univ., Department of Chemistry, Matsumoto, Nagano (Japan)

    2000-10-01

    It is studied that p-BPA (p-bronophenylalanine) which formed complex with catechol functional group has interaction with epinephrine by {sup 11}B-NMR. Two {sup 11}B-NMR resonance signals were observed at pH 7.0. The signal at 29.6 ppm is assigned to p-BPA and at 10.8 ppm is assigned to that of complex. We can determine complex formation constants (logK') in various pH. (author)

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

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  13. Characterization of water in hydrated Bombyx mori silk fibroin fiber and films by 2H NMR relaxation and 13C solid state NMR.

    Science.gov (United States)

    Asakura, Tetsuo; Isobe, Kotaro; Kametani, Shunsuke; Ukpebor, Obehi T; Silverstein, Moshe C; Boutis, Gregory S

    2017-03-01

    The mechanical properties of Bombyx mori silk fibroin (SF), such as elasticity and tensile strength, change remarkably upon hydration. However, the microscopic interaction with water is not currently well understood on a molecular level. In this work, the dynamics of water molecules interacting with SF was studied by 2 H solution NMR relaxation and exchange measurements. Additionally, the conformations of hydrated [3- 13 C]Ala-, [3- 13 C]Ser-, and [3- 13 C]Tyr-SF fibers and films were investigated by 13 C DD/MAS NMR. Using an inverse Laplace transform algorithm, we were able to identify four distinct components in the relaxation times for water in SF fiber. Namely, A: bulk water outside the fiber, B: water molecules trapped weakly on the surface of the fiber, C: bound water molecules located in the inner surface of the fiber, and D: bound water molecules located in the inner part of the fiber were distinguishable. In addition, four components were also observed for water in the SF film immersed in methanol for 30s, while only two components for the film immersed in methanol for 24h. The effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and non-crystalline domains of 13 C selectively labeled SF, respectively, could be determined independently. Our measurements provide new insight relating the characteristics of water and the hydration structure of silk, which are relevant in light of current interest in the design of novel silk-based biomaterials. The mechanical properties of Bombyx mori silk fibroin (SF) change remarkably upon hydration. However, the microscopic interaction between SF and water is not currently well understood on a molecular level. We were able to identify four distinct components in the relaxation times for water in SF fiber by 2 H solution NMR relaxation and exchange measurements. In addition, the effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and

  14. Spirocyclic character of ixazomib citrate revealed by comprehensive XRD, NMR and DFT study

    Czech Academy of Sciences Publication Activity Database

    Skořepová, E.; Čerňa, I.; Vlasáková, R.; Zvoníček, V.; Tkadlecová, M.; Dušek, Michal

    2017-01-01

    Roč. 1148, Nov (2017), s. 22-27 ISSN 0022-2860 R&D Projects: GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : ixazomib citrate * molecular structure * stereoisomers * crystal structure * NMR * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.753, year: 2016

  15. NMR-study of dynamic structural transtions in RNA-molecules

    OpenAIRE

    Fürtig, Boris

    2007-01-01

    The following thesis is concerned with the elucidation of structural changes of RNA molecules during the time course of dynamic processes that are commonly denoted as folding reactions. In contrast to the field of protein folding, the concept of RNA folding comprises not only folding reactions itself but also refolding- or conformational switching- and assembly processes (see chapter III). The method in this thesis to monitor these diverse processes is high resolution liquid-state NMR spectro...

  16. μSR and NMR study of the superconducting Heusler compound YPd2Sn

    Science.gov (United States)

    Saadaoui, H.; Shiroka, T.; Amato, A.; Baines, C.; Luetkens, H.; Pomjakushina, E.; Pomjakushin, V.; Mesot, J.; Pikulski, M.; Morenzoni, E.

    2013-09-01

    We report on muon-spin rotation and relaxation (μSR) and 119Sn nuclear magnetic resonance (NMR) measurements to study the microscopic superconducting and magnetic properties of the Heusler compound with the highest superconducting transition temperature, YPd2Sn (Tc=5.4 K). Measurements in the vortex state provide the temperature dependence of the effective magnetic penetration depth λ(T) and the field dependence of the superconducting gap Δ(0). The results are consistent with a very dirty s-wave BCS superconductor with a gap Δ(0)=0.85(3) meV, λ(0)=212(1) nm, and a Ginzburg-Landau coherence length ξGL(0)≅23 nm. In spite of its very dirty character, the effective density of condensed charge carriers is high compared to that in the normal state. The μSR data in a broad range of applied fields are well reproduced by taking into account a field-related reduction of the effective superconducting gap. Zero-field μSR measurements, sensitive to the possible presence of very small magnetic moments, do not show any indications of magnetism in this compound.

  17. Water speciation in sodium silicate glasses (quenched melts): A comprehensive NMR study

    Science.gov (United States)

    Xue, X.; Kanzaki, M.; Eguchi, J.

    2012-12-01

    Dissolution mechanism of water is an important factor governing how the dissolved water affects the physical and thermodynamic properties of silicate melts and glasses. Our previous studies have demonstrated that 1H MAS NMR in combination with 29Si-1H and 27Al-1H double-resonance NMR experiments is an effective approach for unambiguously differentiating and quantifying different water species in quenched silicate melts (glasses). Several contrasting dissolution mechanisms have been revealed depending on the melt composition: for relatively polymerized melts, the formation of SiOH/AlOH species (plus molecular H2O) and depolymerization of the network structure dominate; whereas for depolymerized Ca-Mg silicate melts, free OH (e.g. MgOH) become increasingly important (cf. [1]). The proportion of free OH species has been shown to decrease with both increasing melt polymerization (silica content) and decreasing field strength of the network modifying cations (from Mg to Ca). Our previous 1H and 29Si MAS NMR results for hydrous Na silicate glasses of limited compositions (Na2Si4O9 and Na2Si2O5) were consistent with negligible free OH (NaOH) species and depolymerizing effect of water dissolution [2]. On the other hand, there were also other studies that proposed the presence of significant NaOH species in hydrous glasses near the Na2Si2O5 composition. The purpose of this study is apply the approach of combined 1H MAS NMR and double-resonance (29Si-1H and 23Na-1H) NMR to gain unambiguous evidence for the OH speciation in Na silicate glasses (melts) as a function of composition. Hydrous Na silicate glasses containing mostly ≤ 1 wt% H2O for a range of Na/Si ratios from 0.33 to 1.33 have been synthesized by rapidly quenching melts either at 0.2 GPa using an internally heated gas pressure vessel or at 1 GPa using a piston cylinder high-pressure apparatus. NMR spectra have been acquired using a 9.4 T Varian Unity-Inova spectrometer. The 29Si and 1H chemical shifts are

  18. Intracellular PHB conversion in a type II methanotroph studied by 13 C NMR

    NARCIS (Netherlands)

    Vecherskaya, M.; Dijkema, C.; Stams, A.J.M.

    2001-01-01

    Poly-g-hydroxybutyrate (PHB) formation under aerobic conditions via incorporation of [13C-2]acetate as a cosubstrate and its intracellular degradation under anaerobic conditions in a Type II methanotroph was studied by 13C NMR. During PHB synthesis in the presence of labelled acetate, low levels of

  19. Dehydration/hydration of granular beds for thermal storage applications: a combined NMR and temperature study

    NARCIS (Netherlands)

    Donkers, P.A.J.; Pel, L.; Adan, O.C.G.

    For heat/cold storage systems a granular bed of salt hydrates is studied during dehydration/hydration. The water density in these beds are measured with help of NMR. Diffusion based dehydration of a granular bed of Na2SO4·10H2O is shown to be internally limited as larger grains dehydrate faster than

  20. Cs{sub 4}P{sub 2}Se{sub 10}: A new compound discovered with the application of solid-state and high temperature NMR

    Energy Technology Data Exchange (ETDEWEB)

    Gave, Matthew A; Canlas, Christian G [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Chung, In [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Iyer, Ratnasabapathy G [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Kanatzidis, Mercouri G [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States)], E-mail: m-kanatzidis@northwestern.edu; Weliky, David P. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: weliky@chemistry.msu.edu

    2007-10-15

    The new compound Cs{sub 4}P{sub 2}Se{sub 10} was serendipitously produced in high purity during a high-temperature synthesis done in a nuclear magnetic resonance (NMR) spectrometer. {sup 31}P magic angle spinning (MAS) NMR of the products of the synthesis revealed that the dominant phosphorus-containing product had a chemical shift of -52.8 ppm that could not be assigned to any known compound. Deep reddish brown well-formed plate-like crystals were isolated from the NMR reaction ampoule and the structure was solved with X-ray diffraction. Cs{sub 4}P{sub 2}Se{sub 10} has the triclinic space group P-1 with a=7.3587(11) A, b=7.4546(11) A, c=10.1420(15) A, {alpha}=85.938(2){sup o}, {beta}=88.055(2){sup o}, and {gamma}=85.609(2){sup o} and contains the [P{sub 2}Se{sub 10}]{sup 4-} anion. To our knowledge, this is the first compound containing this anion that is composed of two tetrahedral (PSe{sub 4}) units connected by a diselenide linkage. It was also possible to form a glass by quenching the melt in ice water, and Cs{sub 4}P{sub 2}Se{sub 10} was recovered upon annealing. The static {sup 31}P NMR spectrum at 350 deg. C contained a single peak with a -35 ppm chemical shift and a {approx}7 ppm peak width. This study highlights the potential of solid-state and high-temperature NMR for aiding discovery of new compounds and for probing the species that exist at high temperature. - Graphical abstract: The new compound Cs{sub 4}P{sub 2}Se{sub 10} was discovered following a high-temperature in situ synthesis in the NMR spectrometer and the structure was determined by single-crystal X-ray diffraction. It contains the new [P{sub 2}Se{sub 10}]{sup 4-} anion.

  1. Solid NMR study of lithium ions accommodated in various transition metal oxides

    International Nuclear Information System (INIS)

    Kanzaki, Yasushi; Suzuki, Noriko

    2008-01-01

    Solid NMR was used to elucidate the lithium accommodation/extraction reaction in various transition metal oxides. The first study was the lithium ion exchange reaction of titanium antimonic acid (TiSbA). The effect of hydration on the selectivity of lithium ion in the solid phase was examined using 7 Li NMR. The second study was the irreversible ion exchange behavior of HNbO 3 . The selectivity for the lithium ion and the irreversible behavior were examined using 1 H and 7 Li NMR. The third study was the isotope separation between 6 Li and 7 Li in various inorganic ion exchangers. The high isotope separation coefficient was ascribed to the degree of dehydration during the ion exchange reaction. The degree of dehydration was examined by 1 H and 7 Li NMR studies. The last study was determining the mechanism of the lithium accommodation/extraction reaction of λ-MnO 2 in an aqueous solution. The different paths between the accommodation and extraction and the formation of MnO 4- during the accommodation were determined by chemical analysis. The Knight shift in the 7 Li MAS-NMR spectra of Li 0.5 MnO 2 suggested the localization of the electron density on the lithium nuclei. An XPS study also suggested the presence of an electron density on the lithium nuclei. A pH-independent redox couple was assumed to account for the accommodation/extraction reaction of lithium ions, such as Li(I)/Li(0). (author)

  2. Ground-state magnetization of the molecular cluster Mn12O12-acetate as seen by proton NMR

    International Nuclear Information System (INIS)

    Furukawa, Y.; Watanabe, K.; Kumagai, K.; Jang, Z. H.; Lascialfari, A.; Borsa, F.; Gatteschi, D.

    2000-01-01

    1 H nuclear magnetic resonance (NMR) measurements have been carried out in Mn 12 O 12 -acetate clusters at low temperature in order to investigate microscopically the static and dynamic magnetic properties of the molecule in its high-spin S=10 ground state. Below liquid helium temperature it is found that the local hyperfine fields at the proton sites are static as expected for the very slow superparamagnetic relaxation of Mn 12 O 12 at low temperature. The magnitude and distribution of the hyperfine fields can be reproduced to a good approximation by considering only the dipolar interaction of protons with the local Mn magnetic moments and by assigning the magnitude and orientation of the local moments of the different Mn 3+ and Mn 4+ ions according to an accepted coupling scheme for the total S=10 ground state. The relaxation time of the macroscopic magnetization of the cluster was measured by monitoring the change of the intensity of the 1 H-NMR shifted lines following inversion of the applied magnetic field. This is possible because the sudden change of the field orientation changes the sign of the shift of the NMR lines in the proton spectrum. Although important differences are noticed, the relaxation time of the magnetization as measured indirectly by the 1 H-NMR method is comparable to the one obtained directly with a superconducting quantum interference device magnetometer. In particular we could reproduce the minima in the relaxation time as a function of magnetic field at the fields for level crossing, minima which are considered to be a signature of the quantum tunneling of the magnetization

  3. Solid state NMR and bioequivalence comparison of the pharmacokinetic parameters of two formulations of clindamycin

    KAUST Repository

    Al-Talla, Zeyad

    2011-01-01

    Objective: The purpose of this study was to compare the pharmacokinetic parameters and determine the bioequivalence of a generic formulation of clindamycin that is sold in the local markets in the Middle East (Clindox® 150 mg capsule; test) with a reference formulation (Dalacin C® 150 mg capsule) in healthy adult male volunteers. Methods: A single-dose, open-label, 2-period crossover study was conducted. Healthy male volunteers were randomly assigned to oral administration of a single treatment of the reference and test formulations. The same groups were given the alternate formulation. After dosing, serial blood samples were withdrawn for a period of 24 h. Serum harvested from the blood samples was analyzed for clindamycin by high performance liquid chromatography (HPLC) with ultraviolet detection. Pharmacokinetic parameters, including AUC0-∞, AUC 0-t, Cmax, Ke, tmax and t 1/2 were determined from the serum concentrations for both formulations (test and reference). The products were tested for bioequivalence after log-transformation of the data. Results: 24 healthy adult male volunteers from Jordan (mean [SD] age, 28.8 (7.7) years (range 19-45 years); height, 175.8 (10.6) cm (range 159.0-192.0 cm); weight, 75.6 (11.0) kg (range 58-101 kg); and body mass index, 24.4 (1.8) kg/m2 (range 21.3-28 kg/m2)) were enrolled in and completed the study. The 13C NMR spectra for both Dalacin C® and Clindox® showed 18 distinct lines associated with the 18 different carbon atoms. Conclusion: The statistical comparison suggested that Clindox® capsules are bioequivalent to Dalacin C® capsules. The 13C CPMAS results confirmed that the two drugs exhibit typical clindamycin spectra. ©2011 Dustri-Verlag Dr. K. Feistle.

  4. Principles of nuclear magnetic resonance (NMR) - current state of the art

    International Nuclear Information System (INIS)

    Lerski, R.A.

    1985-01-01

    Nuclear magnetic resonance (NMR) imaging has progressed rapidly from laboratory curiosity to commercial exploitation and clinical application in the space of only three years. The physical principles underlying the technique are described and the equipment requirements outlined. The question of optimal magnetic field strength is discussed. (author)

  5. On the predictions of the 11B solid state NMR parameters

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Brus, Jiří

    655–656, 1 July (2016), s. 66-70 ISSN 0009-2614 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : NMR * DFT * GIPAW Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.815, year: 2016

  6. Conformational Plasticity of the Cell-Penetrating Peptide SAP As Revealed by Solid-State 19F-NMR and Circular Dichroism Spectroscopies.

    Science.gov (United States)

    Afonin, Sergii; Kubyshkin, Vladimir; Mykhailiuk, Pavel K; Komarov, Igor V; Ulrich, Anne S

    2017-07-13

    The cell-penetrating peptide SAP, which was designed as an amphipathic poly-l-proline helix II (PPII), was suggested to self-assemble into regular fibrils that are relevant for its internalization. Herein we have analyzed the structure of SAP in the membrane-bound state by solid-state 19 F-NMR, which revealed other structural states, in addition to the expected surface-aligned PPII. Trifluoromethyl-bicyclopentyl-glycine (CF 3 -Bpg) and two rigid isomers of trifluoromethyl-4,5-methanoprolines (CF 3 -MePro) were used as labels for 19 F-NMR analysis. The equilibria between different conformations of SAP were studied and were found to be shifted by the substituents at Pro-11. Synchrotron-CD results suggested that substituting Pro-11 by CF 3 -MePro governed the coil-to-PPII equilibrium in solution and in the presence of a lipid bilayer. Using CD and 19 F-NMR, we examined the slow kinetics of the association of SAP with membranes and the dependence of the SAP conformational dynamics on the lipid composition. The peptide did not bind to lipids in the solid ordered phase and aggregated only in the liquid ordered "raft"-like bilayers. Self-association could not be detected in solution or in the presence of liquid disordered membranes. Surface-bound amphipathic SAP in a nonaggregated state was structured as a mixture of nonideal extended conformations reflecting the equilibrium already present in solution, i.e., before binding to the membrane.

  7. Integrating Solid-State NMR and Computational Modeling to Investigate the Structure and Dynamics of Membrane-Associated Ghrelin

    Science.gov (United States)

    Els-Heindl, Sylvia; Chollet, Constance; Scheidt, Holger A.; Beck-Sickinger, Annette G.; Meiler, Jens; Huster, Daniel

    2015-01-01

    The peptide hormone ghrelin activates the growth hormone secretagogue receptor 1a, also known as the ghrelin receptor. This 28-residue peptide is acylated at Ser3 and is the only peptide hormone in the human body that is lipid-modified by an octanoyl group. Little is known about the structure and dynamics of membrane-associated ghrelin. We carried out solid-state NMR studies of ghrelin in lipid vesicles, followed by computational modeling of the peptide using Rosetta. Isotropic chemical shift data of isotopically labeled ghrelin provide information about the peptide’s secondary structure. Spin diffusion experiments indicate that ghrelin binds to membranes via its lipidated Ser3. Further, Phe4, as well as electrostatics involving the peptide’s positively charged residues and lipid polar headgroups, contribute to the binding energy. Other than the lipid anchor, ghrelin is highly flexible and mobile at the membrane surface. This observation is supported by our predicted model ensemble, which is in good agreement with experimentally determined chemical shifts. In the final ensemble of models, residues 8–17 form an α-helix, while residues 21–23 and 26–27 often adopt a polyproline II helical conformation. These helices appear to assist the peptide in forming an amphipathic conformation so that it can bind to the membrane. PMID:25803439

  8. Integrating solid-state NMR and computational modeling to investigate the structure and dynamics of membrane-associated ghrelin.

    Directory of Open Access Journals (Sweden)

    Gerrit Vortmeier

    Full Text Available The peptide hormone ghrelin activates the growth hormone secretagogue receptor 1a, also known as the ghrelin receptor. This 28-residue peptide is acylated at Ser3 and is the only peptide hormone in the human body that is lipid-modified by an octanoyl group. Little is known about the structure and dynamics of membrane-associated ghrelin. We carried out solid-state NMR studies of ghrelin in lipid vesicles, followed by computational modeling of the peptide using Rosetta. Isotropic chemical shift data of isotopically labeled ghrelin provide information about the peptide's secondary structure. Spin diffusion experiments indicate that ghrelin binds to membranes via its lipidated Ser3. Further, Phe4, as well as electrostatics involving the peptide's positively charged residues and lipid polar headgroups, contribute to the binding energy. Other than the lipid anchor, ghrelin is highly flexible and mobile at the membrane surface. This observation is supported by our predicted model ensemble, which is in good agreement with experimentally determined chemical shifts. In the final ensemble of models, residues 8-17 form an α-helix, while residues 21-23 and 26-27 often adopt a polyproline II helical conformation. These helices appear to assist the peptide in forming an amphipathic conformation so that it can bind to the membrane.

  9. Measurements of relative chemical shift tensor orientations in solid-state NMR: new slow magic angle spinning dipolar recoupling experiments.

    Science.gov (United States)

    Jurd, Andrew P S; Titman, Jeremy J

    2009-08-28

    Solid-state NMR experiments can be used to determine conformational parameters, such as interatomic distances and torsion angles. The latter can be obtained from measurements of the relative orientation of two chemical shift tensors, if the orientation of these with respect to the surrounding bonds is known. In this paper, a new rotor-synchronized magic angle spinning (MAS) dipolar correlation experiment is described which can be used in this way. Because the experiment requires slow MAS rates, a novel recoupling sequence, designed using symmetry principles, is incorporated into the mixing period. This recoupling sequence is based in turn on a new composite cyclic pulse referred to as COAST (for combined offset and anisotropy stabilization). The new COAST-C7(2)(1) sequence is shown to give good theoretical and experimental recoupling efficiency, even when the CSA far exceeds the MAS rate. In this regime, previous recoupling sequences, such as POST-C7(2)(1), exhibit poor recoupling performance. The effectiveness of the new method has been explored by a study of the dipeptide L-phenylalanyl-L-phenylalanine.

  10. Study of conformation and dynamic of surfactant molecules in graphite oxide via NMR

    Energy Technology Data Exchange (ETDEWEB)

    Ai, X.Q. [Jiangsu Second Normal University, College of Physics and Electronic Engineering, Nanjing (China); Ma, L.G. [Nanjing Xiaozhuang University, School of Electronic Engineering, Nanjing (China)

    2016-08-15

    The conformation and dynamic of surfactant in graphite oxide (GO) was investigated by solid-state {sup 13}C magic-angle-spinning NMR and {sup 1}H-{sup 13}C cross-polarization/magic-angle-spinning NMR spectra. The conformation ordering of the alkyl chains in the confined system shows strong dependence on its orientation. While the alkyl chains parallel to the GO layer in lateral monolayer arrangement are in gauche conformation in addition to a small amount of all-trans conformation, those with orientation radiating away from the GO in paraffin bilayer arrangement is in all-trans conformation in addition to some gauche conformation even though high-order diffraction peaks appears. NMR results suggest that the least mobile segment is located at the GO-surfactant interface corresponding to the N-methylene group. Further from it, the mobility of the alkyl chain increases. The terminal methyl and N-methyl carbon groups have the highest mobile. The chains in all-trans conformational state are characterized as more rigid than chains with gauche conformation; each segment of the confined alkyl chains with the lateral monolayer arrangement exhibits less mobility as compared to that with the paraffin bilayer arrangement. (orig.)

  11. NMR study of hexanucleotide d(CCGCGG)2 containing two triplet repeats of fragile X syndrome

    International Nuclear Information System (INIS)

    Monleon, Daniel; Esteve, Vicent; Celda, Bernardo

    2003-01-01

    Long repeated stretches of d(CCG) and tri-nucleotide are crucial mutations that cause hereditary forms of mental retardation (fragile X-syndrome). Moreover, the alternating (CG) di-nucleotide is one of the candidates for Z-DNA conformation. Solution NMR structure of d(CCGCGG) 2 has been solved and is discussed. The determined NMR solution structure is a distorted highly bent B-DNA conformation with increased flexibility in both terminal residues. This conformation differs significantly from the Z-DNA tetramer structure reported for the same hexamer in the crystal state at similar ionic strength by Malinina and co-workers. Crystal structure of d(CCGCGG) 2 at high salt concentration includes a central alternating tetramer in Z-DNA conformation, while the initial cytosine swings out and forms a Watson-Crick base-pair with the terminal guanine of a symmetry-related molecule. In solution, NMR data for sugar ring puckering combined with restrained molecular dynamics simulations starting from a Z-DNA form show that terminal furanose residues could adopt the conformation required for aromatic bases swinging out. Therefore, tetramer formation could be considered possible once the hexanucleotide had previously adopted the Z-DNA form. This work gives some insight into correlations between anomalous crystal structures and their accessibility in the solution state

  12. Effect of pressure on the short-range structure and speciation of carbon in alkali silicate and aluminosilicate glasses and melts at high pressure up to 8 GPa: 13C, 27Al, 17O and 29Si solid-state NMR study

    Science.gov (United States)

    Kim, Eun Jeong; Fei, Yingwei; Lee, Sung Keun

    2018-03-01

    Despite the pioneering efforts to explore the nature of carbon in carbon-bearing silicate melts under compression, experimental data for the speciation and the solubility of carbon in silicate melts above 4 GPa have not been reported. Here, we explore the speciation of carbon and pressure-induced changes in network structures of carbon-bearing silicate (Na2O-3SiO2, NS3) and sodium aluminosilicate (NaAlSi3O8, albite) glasses quenched from melts at high pressure up to 8 GPa using multi-nuclear solid-state NMR. The 27Al triple quantum (3Q) MAS NMR spectra for carbon-bearing albite melts revealed the pressure-induced increase in the topological disorder around 4 coordinated Al ([4]Al) without forming [5,6]Al. These structural changes are similar to those in volatile-free albite melts at high pressure, indicating that the addition of CO2 in silicate melts may not induce any additional increase in the topological disorder around Al at high pressure. 13C MAS NMR spectra for carbon-bearing albite melts show multiple carbonate species, including [4]Si(CO3)[4]Si, [4]Si(CO3)[4]Al, [4]Al(CO3)[4]Al, and free CO32-. The fraction of [4]Si(CO3)[4]Al increases with increasing pressure, while those of other bridging carbonate species decrease, indicating that the addition of CO2 may enhance mixing of Si and Al at high pressure. A noticeable change is not observed for 29Si NMR spectra for the carbon-bearing albite glasses with varying pressure at 1.5-6 GPa. These NMR results confirm that the densification mechanisms established for fluid-free, polymerized aluminosilicate melts can be applied to the carbon-bearing albite melts at high pressure. In contrast, the 29Si MAS NMR spectra for partially depolymerized, carbon-bearing NS3 glasses show that the fraction of [5,6]Si increases with increasing pressure at the expense of Q3 species ([4]Si species with one non-bridging oxygen as the nearest neighbor). The pressure-induced increase in topological disorder around Si is evident from an

  13. In situ NMR and modeling studies of nitroxide mediated copolymerization of styrene and n-butyl acrylate

    NARCIS (Netherlands)

    Hlalele, L.; Klumperman, L.

    2011-01-01

    The combination of in situ1H NMR and in situ31P NMR was used to study the nitroxide mediated copolymerization of styrene and n-butyl acrylate. The alkoxyamine MAMA-DEPN was employed to initiate and mediate the copolymerization. The nature of the ultimate/terminal monomer units of dormant polymer

  14. Study of acute biochemical effects of thallium toxicity in mouse urine by NMR spectroscopy.

    Science.gov (United States)

    Tyagi, Ritu; Rana, Poonam; Khan, Ahmad Raza; Bhatnagar, Deepak; Devi, M Memita; Chaturvedi, Shubhra; Tripathi, Rajendra P; Khushu, Subash

    2011-10-01

    Thallium (Tl) is a toxic heavy metal and its exposure to the human body causes physiological and biochemical changes due to its interference with potassium-dependent biological reactions. A high-resolution (1)H NMR spectroscopy based metabonomic approach has been applied for investigating acute biochemical effects caused by thallium sulfate (Tl(2)SO(4)). Male strain A mice were divided in three groups and received three doses of Tl(2)SO(4) (5, 10 and 20 mg kg(-1) b.w., i.p.). Urine samples collected at 3, 24, 72 and 96 h post-dose time points were analyzed by (1)H NMR spectroscopy. NMR spectral data were processed and analyzed using principal components analysis to represent biochemical variations induced by Tl(2)SO(4). Results showed Tl-exposed mice urine to have distinct metabonomic phenotypes and revealed dose- and time-dependent clustering of treated groups. The metabolic signature of urine analysis from Tl(2)SO(4)-treated animals exhibited an increase in the levels of creatinine, taurine, hippurate and β-hydroxybutyrate along with a decrease in energy metabolites trimethylamine and choline. These findings revealed Tl-induced disturbed gut flora, membrane metabolite, energy and protein metabolism, representing physiological dysfunction of vital organs. The present study indicates the great potential of NMR-based metabonomics in mapping metabolic response for toxicology, which could ultimately lead to identification of potential markers for Tl toxicity. Copyright © 2011 John Wiley & Sons, Ltd.

  15. Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective.

    Science.gov (United States)

    Tian, Donglin; Li, Tao; Zhang, Rongchun; Wu, Qiang; Chen, Tiehong; Sun, Pingchuan; Ramamoorthy, Ayyalusamy

    2017-06-29

    Fabricating materials with excellent mechanical performance from the natural renewable and degradable biopolymers has drawn significant attention in recent decades due to the environmental concerns and energy crisis. As two of the most promising substitutes of synthetic polymers, silk fibroin (SF), and cellulose, have been widely used in the field of textile, biomedicine, biotechnology, etc. Particularly, the cellulose/SF blend film exhibits better strength and toughness than that of regenerated cellulose film. Herein, this study is aimed to understand the molecular origin of the enhanced mechanical properties for the cellulose/SF blend film, using solid-state NMR as a main tool to investigate the conformational changes, intermolecular interactions between cellulose and SF and the water organization. It is found that the content of the β-sheet structure is increased in the cellulose/SF blend film with respect to the regenerated SF film, accompanied by the reduction of the content of random coil structures. In addition, the strong hydrogen bonding interaction between the SF and cellulose is clearly elucidated by the two-dimensional (2D) 1 H- 13 C heteronuclear correlation (HETCOR) NMR experiments, demonstrating that the SF and cellulose are miscible at the molecular level. Moreover, it is also found that the -NH groups of SF prefer to form hydrogen bonds with the hydroxyl groups bonded to carbons C2 and C3 of cellulose, while the hydroxyl groups bonded to carbon C6 and the ether oxygen are less favorable for hydrogen bonding interactions with the -NH groups of SF. Interestingly, bound water is found to be present in the air-dried cellulose/SF blend film, which is predominantly associated with the cellulose backbones as determined by 2D 1 H- 13 C wide-line-separation (WISE) experiments with spin diffusion. This clearly reveals the presence of nanoheterogeneity in the cellulose/SF blend film, although cellulose and SF are miscible at a molecular level. Without doubt

  16. Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR

    Science.gov (United States)

    Yau, Wai-Ming; Thurber, Kent R.; Tycko, Robert

    2014-07-01

    We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25-30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2-6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92-128 for cross-polarized 13C NMR signals from 15N,13C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6-3.8 s for 1H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute 13C NMR signal amplitudes and build-up times, are approximately 2-4 times lower than with the best triradicals.

  17. Molecular composition of recycled organic wastes, as determined by solid-state {sup 13}C NMR and elemental analyses

    Energy Technology Data Exchange (ETDEWEB)

    Eldridge, S.M., E-mail: simon.eldridge@dpi.nsw.gov.au [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); NSW Department of Primary Industries, Bruxner Highway, Wollongbar, NSW 2477 (Australia); Chen, C.R. [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); Xu, Z.H. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Nelson, P.N. [School of Earth and Environmental Sciences, James Cook University, Cairns, QLD 4870 (Australia); Boyd, S.E. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Meszaros, I. [Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia); Chan, K.Y. [Graduate School of Environment, Macquarie University, North Ryde, NSW 2109 (Australia); Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia)

    2013-11-15

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state {sup 13}C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

  18. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Son-Jong, E-mail: Sonjong@cheme.caltech.edu [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Hyun-Sook [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); To, Magnus [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Young-Su; Cho, Young Whan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Hyungkeun; Kim, Chul [Department of Chemistry, Hannam University, Daejeon 305-811 (Korea, Republic of)

    2015-10-05

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH{sub 4} crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of {sup 1}H–{sup 11}B in LiBH{sub 4} was monitored in series of VT NMR spectra to probe translational mobility of LiBH{sub 4} that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH{sub 4}–Ca(BH{sub 4}){sub 2} mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH{sub 4} that has been proven to be highly versatile in many energy related applications.

  19. Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses

    International Nuclear Information System (INIS)

    Eldridge, S.M.; Chen, C.R.; Xu, Z.H.; Nelson, P.N.; Boyd, S.E.; Meszaros, I.; Chan, K.Y.

    2013-01-01

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state 13 C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes

  20. NMR and luminescence spectroscopy study of formation of mixed β-diketonate europium complexes

    International Nuclear Information System (INIS)

    Kavun, V.Ya.; Kalinovskaya, I.V.; Karasev, V.E.; Chernyshov, B.N.; Steblevskaya, N.I.

    1987-01-01

    Methods of NMR ('H, 19 F) and luminescent spectroscopy were applied to study ligand substitution in Eu(β-dik) 3 phen-CDCl 3 -(β-dik)' systems, where β-dik-acetylacetone (AA) and hexafluoroacetyl-acetone (HFAA), phen-1.10-phenathroline at different mole ratio (m) of competing ligands (m=AA/HFAA). Formation of mixed Eu(AA) 2 (HFAA)phen and Eu(AA)(HFAA) 2 phen complexes is proved; calculation of the stark structure of 5 D 0 - 7 F j (j=0,1,2) transitions in low-temperature luminescence spectra is conducted for these complexes. It is stated that at minimum HFAA concentration in the solution the latter replaces AA from europium coordination sphere. It is shown that depending on the value in substitution of acidoligands proceeds successfully by the equations Eu(AA) 3 phen+(NHFAA) n → Eu(AA) 3-n → (HFAA) n phen+(NAA) n ; (n=1,2,3)

  1. Nitrogen Use Efficiency and Carbon Isotope Discrimination Study on NMR151 and NMR152 Mutant Lines Rice at Field Under Different Nitrogen Rates and Water Potentials

    International Nuclear Information System (INIS)

    Ahmad Nazrul Abdul Wahid; Shyful Azizi Abdul Rahman; Abdul Rahim Harun; Latiffah Nordin; Abdul Razak Ruslan; Hazlina Abdullah; Khairuddin Abdul Rahim

    2016-01-01

    This study was conducted to evaluate the nitrogen use efficiency and "1"3C isotope discrimination of rice mutant lines viz. NMR151 and NMR152. Both cultivars are developed under rice radiation mutagenesis programme for adaptability to aerobic conditions. In the present study, NMR151 and NMR152 were grown under conditions of varying water potentials and nitrogen levels in a field. Two water potentials and three nitrogen rates in a completely randomized design with three replications were carried out. The rice mutants were grown for 110 days under two water potentials, (i) Field capacity from 0 to 110 DAS [FC], and (ii) Field capacity from 0 to 40 DAS and 30 % dry of field capacity from 41 to 110 DAS [SS] and three nitrogen rates, (i) 0 kg N/ ha (0N), (ii) 60 kg N/ ha (60N), and (iii) 120 kg N/ ha (120N). "1"5N isotopic tracer technique was used in this study, whereby the "1"5N labeled urea fertilizer 5.20 % atom excess (a.e) was utilized as a tracer for nitrogen use efficiency (NUE) study. "1"5N isotope presence in the samples was determined using emission spectrometry and percentage of total nitrogen was determined by the Kjeldahl method. "1"5N a.e values of the samples were used in the determination of the NUE. The value of "1"3C isotope discrimination (Δ"1"3C) in the sample was determined using isotope ratio mass spectrometry (IRMS). The "1"3C isotope discrimination technique was used as a tool to identify drought resistance rice cultivars with improves water use efficiency. The growth and agronomy data, viz. plant height, number of tillers, grain yield, straw yield, and 1000 grain weight also were recorded. Results from this study showed nitrogen rates imparted significant effects on yield (grain and straw) plant height, number of tillers and 1000 grain weight. Water potentials had significant effects only on 1000 grain weight and Δ"1"3C. The NUE for both mutant lines rice showed no significant different between treatments. Both Rice mutant lines rice NMR151

  2. NMR-CT scanner

    International Nuclear Information System (INIS)

    Kose, Katsumi; Sato, Kozo; Sugimoto, Hiroshi; Sato, Masataka.

    1983-01-01

    A brief explanation is made on the imaging methods for a practical diagnostic NMR-CT scanner : A whole-body NMR-CT scanner utilizing a resistive magnet has been developed by Toshiba in cooperation with the Institute for Solid State Physics, the University of Tokyo. Typical NMR-CT images of volunteers and patients obtained in the clinical experiments using this device are presented. Detailed specifications are also shown about the practical NMR-CTs which are to be put on the market after obtaining the government approval. (author)

  3. 2H Solid-State NMR Analysis of the Dynamics and Organization of Water in Hydrated Chitosan

    Directory of Open Access Journals (Sweden)

    Fenfen Wang

    2016-04-01

    Full Text Available Understanding water–biopolymer interactions, which strongly affect the function and properties of biopolymer-based tissue engineering and drug delivery materials, remains a challenge. Chitosan, which is an important biopolymer for the construction of artificial tissue grafts and for drug delivery, has attracted extensive attention in recent decades, where neutralization with an alkali solution can substantially enhance the final properties of chitosan films cast from an acidic solution. In this work, to elucidate the effect of water on the properties of chitosan films, we investigated the dynamics and different states of water in non-neutralized (CTS-A and neutralized (CTS-N hydrated chitosan by mobility selective variable-temperature (VT 2H solid-state NMR spectroscopy. Four distinct types of water exist in all of the samples with regards to dynamic behavior. First, non-freezable, rigid and strongly bound water was found in the crystalline domain at low temperatures. The second component consists of weakly bound water, which is highly mobile and exhibits isotropic motion, even below 260 K. Another type of water undergoes well-defined 180° flips around their bisector axis. Moreover, free water is also present in the films. For the CTS-A sample in particular, another special water species were bounded to acetic acid molecules via strong hydrogen bonding. In the case of CTS-N, the onset of motions of the weakly bound water molecules at 260 K was revealed by 2H-NMR spectroscopy. This water is not crystalline, even below 260 K, which is also the major contribution to the flexibility of chitosan chains and thus toughness of materials. By contrast, such motion was not observed in CTS-A. On the basis of the 2H solid-state NMR results, it is concluded that the unique toughness of CTS-N mainly originates from the weakly bound water as well as the interactions between water and the chitosan chains.

  4. Biomolecular solid state NMR with magic-angle spinning at 25K.

    Science.gov (United States)

    Thurber, Kent R; Tycko, Robert

    2008-12-01

    A magic-angle spinning (MAS) probe has been constructed which allows the sample to be cooled with helium, while the MAS bearing and drive gases are nitrogen. The sample can be cooled to 25K using roughly 3 L/h of liquid helium, while the 4-mm diameter rotor spins at 6.7 kHz with good stability (+/-5 Hz) for many hours. Proton decoupling fields up to at least 130 kHz can be applied. This helium-cooled MAS probe enables a variety of one-dimensional and two-dimensional NMR experiments on biomolecular solids and other materials at low temperatures, with signal-to-noise proportional to 1/T. We show examples of low-temperature (13)C NMR data for two biomolecular samples, namely the peptide Abeta(14-23) in the form of amyloid fibrils and the protein HP35 in frozen glycerol/water solution. Issues related to temperature calibration, spin-lattice relaxation at low temperatures, paramagnetic doping of frozen solutions, and (13)C MAS NMR linewidths are discussed.

  5. Spectroscopic techniques (Moessbauer spectrometry, NMR, ESR...) as tools to resolve doubtful NMR images: Study of the craniopharyngioma tumor

    International Nuclear Information System (INIS)

    Rimbert, J.N.; Dumas, F.; Lafargue, C.; Kellershohn, C.; Brunelle, F.; Lallemand, D.

    1990-01-01

    Craniopharyngioma, an intracranial tumor, exhibits hyperintensity in the Spin-Echo-T 2 -NMR image and a hyposignal in the SE-T 1 -image. However, in some cases (15-20% cases), hypersignals are seen in both SE-T 1 and T 2 -MRI. Using spectroscopic techniques, Moessbauer spectrometry in particular, we have demonstrated that the T 1 hypersignal is due to ferritin, dissolved in the cystic liquid, after tumor cell lysis, in the course of time. Other possible reasons inducing a shortening of the T 1 relaxation time (presence of lipids, intratumoral hemorrhage) have been rejected. (orig.)

  6. Nano-mole scale sequential signal assignment by 1 H-detected protein solid-state NMR

    KAUST Repository

    Wang, Songlin; Parthasarathy, Sudhakar; Xiao, Yiling; Nishiyama, Yusuke; Long, Fei; Matsuda, Isamu; Endo, Yuki; Nemoto, Takahiro; Yamauchi, Kazuo; Asakura, Tetsuo; Takeda, Mitsuhiro; Terauchi, Tsutomu; Kainosho, Masatsune; Ishii, Yoshitaka

    2015-01-01

    We present a 3D 1H-detected solid-state NMR (SSNMR) approach for main-chain signal assignments of 10-100 nmol of fully protonated proteins using ultra-fast magic-angle spinning (MAS) at ∼80 kHz by a novel spectral-editing method, which permits drastic spectral simplification. The approach offers ∼110 fold time saving over a traditional 3D 13C-detected SSNMR approach. This journal is © The Royal Society of Chemistry 2015.

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

    OpenAIRE

    Jan H. van der Westhuizen; David G. Reid; Melinda J. Duer; Susan L. Bonnet; Frederik H. Romer; Andrew P. Underwood; Nadine D. Senekal

    2011-01-01

    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 tann...

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

    International Nuclear Information System (INIS)

    Luo Xuechun; Yan Yongbin; Zhang Riqing; Fan Lili

    2001-01-01

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

  9. Comparative NMR study of nPrBTP and iPrBTP

    Energy Technology Data Exchange (ETDEWEB)

    Adam, C.; Muellich, U.; Geist, A.; Geckeis, H. [Karlsruhe Institute of Technology - KIT, Institute for Nuclear Waste Disposal - INE, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rohde, V. [Fraunhofer Institute for Chemical Technology - ICT, Environmental Engineering, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany); Kaden, P. [Helmholtz-Zentrum Dresden - Rossendorf e. V., Institute of Resource Ecology, Bautzner Landstrasse 400, 01328 Dresden (Germany); Panak, P.J. [Karlsruhe Institute of Technology - KIT, Institute for Nuclear Waste Disposal - INE, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); University of Heidelberg, Department of Physical Chemistry, Im Neuenheimer Feld 253, 69120 Heidelberg (Germany)

    2016-07-01

    Bis-triazinyl-pyridine type ligands are important extracting agents for separating trivalent actinide ions from trivalent lanthanides. The alkyl substituents on the lateral triazine rings have a significant effect on the stability of the ligand against hydrolysis and radiolysis. Furthermore they influence solubility, extraction behaviour and selectivity. TRLFS and extraction studies suggest differences in complexation and extraction behaviour of BTP ligands bearing iso-propyl or n-propyl substituents, respectively. As NMR studies allow insight into the metal-ligand bonding, we conducted NMR studies on a range of {sup 15}N-labelled nPrBTP and iPrBTP Ln(III) and Am(III) complexes. Our results show that no strong change in the metal-ligand bonding occurs, thus excluding electronic reasons for differences in complexation behaviour, extraction kinetics and selectivity. This supports mechanistic reasons for the observed differences. (authors)

  10. Direct NMR Evidence that Transient Tautomeric and Anionic States in dG·dT Form Watson-Crick-like Base Pairs.

    Science.gov (United States)

    Szymanski, Eric S; Kimsey, Isaac J; Al-Hashimi, Hashim M

    2017-03-29

    The replicative and translational machinery utilizes the unique geometry of canonical G·C and A·T/U Watson-Crick base pairs to discriminate against DNA and RNA mismatches in order to ensure high fidelity replication, transcription, and translation. There is growing evidence that spontaneous errors occur when mismatches adopt a Watson-Crick-like geometry through tautomerization and/or ionization of the bases. Studies employing NMR relaxation dispersion recently showed that wobble dG·dT and rG·rU mismatches in DNA and RNA duplexes transiently form tautomeric and anionic species with probabilities (≈0.01-0.40%) that are in concordance with replicative and translational errors. Although computational studies indicate that these exceptionally short-lived and low-abundance species form Watson-Crick-like base pairs, their conformation could not be directly deduced from the experimental data, and alternative pairing geometries could not be ruled out. Here, we report direct NMR evidence that the transient tautomeric and anionic species form hydrogen-bonded Watson-Crick-like base pairs. A guanine-to-inosine substitution, which selectively knocks out a Watson-Crick-type (G)N2H 2 ···O2(T) hydrogen bond, significantly destabilized the transient tautomeric and anionic species, as assessed by lack of any detectable chemical exchange by imino nitrogen rotating frame spin relaxation (R 1ρ ) experiments. An 15 N R 1ρ NMR experiment targeting the amino nitrogen of guanine (dG-N2) provides direct evidence for Watson-Crick (G)N2H 2 ···O2(T) hydrogen bonding in the transient tautomeric state. The strategy presented in this work can be generally applied to examine hydrogen-bonding patterns in nucleic acid transient states including in other tautomeric and anionic species that are postulated to play roles in replication and translational errors.

  11. The microscopic NMR probe in chiral magnets. Zero field-, field-modulated- and Skyrmion- states in FeGe and MnSi

    Energy Technology Data Exchange (ETDEWEB)

    Baenitz, Michael; Yasuoka, Hiroshi; Majumder, Mayukh; Khuntia, Panchanan; Schmidt, Marcus [MPI for the Chemical Physics of Solids, Dresden (Germany); Witt, Sebastian; Krellner, Cornelius [Goethe University, Frankfurt am Main (Germany)

    2016-07-01

    Cubic FeGe is a prototype B20 chiral magnet (T{sub c} = 280 K) which allows to study chiral correlations directly ''on-site'' via the{sup 57}Fe nucleus because of its S=1/2 nuclear spin interacting only with the electron spin moment. NMR provides the static and dynamic staggered local magnetization M{sub Q} through the hyperfine field (H{sub hf}) and the spin lattice relaxation rate (SLRR = 1/T{sub 1}). Measurements were performed on randomly oriented {sup 57}Fe enriched FeGe single crystals between 2-300 K. Helical-, conical- and field-polarized-states could be clearly identified and spin dynamics of each phase was investigated. MnSi single crystals and {sup 29}Si enriched MnSi polycrystals were studied by {sup 29}Si-NMR (S=1/2) in the ordered state (T{sub c} = 29 K) and above. The T- and H- dependence of H{sub hf} and SLRR was investigated in great detail for both FeGe and MnSi.The {sup 29}Si-NMR lines in MnSi are narrow and H{sub hf}-values obtained are smaller than in FeGe. Our results are in general accordance with the extended SCR theory for itinerant helical magnets, although the theory does not include the symmetry breaking in the B20 structure and the multi-band nature. For FeGe correlations are complex due to its more localized magnetism.

  12. Spying on Fe ions and their role in modified aluminosilicates during the sorption of anions using solid-state NMR spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kobera, Libor; Abbrent, Sabina; Holcova, L.; Urbanová, Martina; Koloušek, D.; Doušová, B.; Brus, Jiří

    2017-01-01

    Roč. 241, 15 March (2017), s. 115-122 ISSN 1387-1811 R&D Projects: GA ČR(CZ) GA13-24155S; GA ČR(CZ) GA16-13778S Institutional support: RVO:61389013 Keywords : paramagnetic NMR shift * solid-state NMR * aluminosilicate Subject RIV: JN - Civil Engineering OBOR OECD: Civil engineering Impact factor: 3.615, year: 2016

  13. Investigation of Sc(3) state in nonaqueous solutions by the 45Sc NMR method of high permission

    International Nuclear Information System (INIS)

    Buslaev, Yu.A.; Kirakosyan, G.A.; Tarasov, V.P.

    1980-01-01

    The ScCl 3 + CH 3 CN and ScCl 3 + KNCS + CH 3 CN solutions have been studied by a high-resolution NMR 45 Sc method. It has been estimated that in acetonitrile solutions, with competing ligands of Cl - and NCS - being available, hexacoordination Sc(3) complexes of various compositions are formed, and solvent molecules also take part in formation of the coordination sphere of scandium. Chemical shifts in NMR 45 Sc signals depend linearly on the number of chlor- or NCS - ions bound to scandium(3). This made it possible to determine the value of chemical shifts in signals of all 28 potential complexes formed in a system with three competing ligands

  14. NMR studies of myocardial energy metabolism and ionic homeostasis during ischemia and reperfusion

    International Nuclear Information System (INIS)

    Kirkels, J.H.

    1989-01-01

    In this study several aspects of myocardial energy metabolism and ionic homeostasis during ischemia and reperfusion were investigated in isolated perfused rat hearts, regionally ischemic rabbit hearts, and ex vivo human donor hearts during long term hypothermic cardioplegia. Phosphorus-31 nuclear magnetic resonance ( 31 P NMR) spectroscopy was used as a powerful tool to non-destructively follow the time course in changes in intracellular high-energy phosphates, (creatine phosphate and ATP), inorganic phosphate, and pH. In addition, changes in intracellular free magnesium were followed during ischemia and reperfusion. Sodium-23 ( 23 Na) NMR spectroscopy was used to study intracellular sodium during ischemia and reperfusion and during calcium-free perfusion. (author). 495 refs.; 33 figs.; 11 tabs

  15. Coexistence of spin frozen state and persistent spin dynamics in NaSrCo{sub 2}F{sub 7} as probed by μSR and NMR

    Energy Technology Data Exchange (ETDEWEB)

    Dengre, Shanu; Sarkar, Rajib; Braeuninger, Sascha Albert; Brueckner, Felix; Materne, Philipp; Klauss, Hans-Henning [Institute for Solid State Physics, TU Dresden (Germany); Krizan, Jason W.; Cava, Robert J. [Department of Chemistry, Princeton University, Princeton, NJ (United States); Luetkens, Hubertus; Baines, Chris [Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, Villigen (Switzerland)

    2016-07-01

    {sup 23}Na -and {sup 19}F NMR, and μSR experiments are performed to explore the microscopic properties of NaSrCo{sub 2}F{sub 7}, which is a newly discovered magnetically frustrated pyrochlore with weak bond disorder and with a frustration index of f = 42. While {sup 23}Na and {sup 19}F NMR experiments clearly suggest the presence of quasi static field distribution below ∝3 K as reflected in the huge NMR line broadening and wipe out effect of NMR signal intensity, μSR experiments on the other hand remains passive to this spin frozen state. Both NMR and μSR results indicate the slowing down of the magnetic (spin) fluctuations upon cooling towards the NMR spin frozen state. μSR relaxation rate increases slightly below ∝ 3 K, and remains not only constant down to 20 mK, but also stands independent in longitudinal magnetic field upto 4000 G implying that the spin fluctuations are dynamic. These observations suggest the coexistence of partial spin frozen state and persistent spin dynamics in NaSrCo{sub 2}F{sub 7}.

  16. Determination of structural topology of a membrane protein in lipid bilayers using polarization optimized experiments (POE) for static and MAS solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mote, Kaustubh R. [University of Minnesota, Department of Chemistry (United States); Gopinath, T. [University of Minnesota, Department of Biochemistry, Molecular Biology and Biophysics (United States); Veglia, Gianluigi, E-mail: vegli001@umn.edu [University of Minnesota, Department of Chemistry (United States)

    2013-10-15

    The low sensitivity inherent to both the static and magic angle spinning techniques of solid-state NMR (ssNMR) spectroscopy has thus far limited the routine application of multidimensional experiments to determine the structure of membrane proteins in lipid bilayers. Here, we demonstrate the advantage of using a recently developed class of experiments, polarization optimized experiments, for both static and MAS spectroscopy to achieve higher sensitivity and substantial time-savings for 2D and 3D experiments. We used sarcolipin, a single pass membrane protein, reconstituted in oriented bicelles (for oriented ssNMR) and multilamellar vesicles (for MAS ssNMR) as a benchmark. The restraints derived by these experiments are then combined into a hybrid energy function to allow simultaneous determination of structure and topology. The resulting structural ensemble converged to a helical conformation with a backbone RMSD {approx}0.44 A, a tilt angle of 24 Degree-Sign {+-} 1 Degree-Sign , and an azimuthal angle of 55 Degree-Sign {+-} 6 Degree-Sign . This work represents a crucial first step toward obtaining high-resolution structures of large membrane proteins using combined multidimensional oriented solid-state NMR and magic angle spinning solid-state NMR.

  17. Ab initio study, investigation of NMR shielding tensors, NBO and ...

    African Journals Online (AJOL)

    The electrochemical oxidation of dopamine and 3,4-dihydroxymethamphetamine (HHMA) has been studied in the presence of GSH and cysteine as a nucleophile. In order to determine the optimized geometries, energies, dipole moments, atomic charges, thermochemical analysis and other properties, we performed ...

  18. The in-vitro study of human blood leukemic cells by pulsed NMR

    International Nuclear Information System (INIS)

    Zulkarnaen, M.; Munawir; Wibowo, Tono; Suyitno, Gogot

    1983-01-01

    The diagram of leukemic cells in human blood has been studied by using the NMR longitudinal relaxation technique. The observation was treated in whole blood, serum and blood cell. Every result was compared with previous observation and show that the values of the proton longitudinal relaxation in the leukemic whole blood almost twice or more that of normal blood, while in the serum and the blood cell, the values are nearly the same. (author)

  19. NMR study of the 1-13C glucose colon bacterial metabolism

    International Nuclear Information System (INIS)

    Briet, F.; Flourie, B.; Pochart, P.; Rambaud, J.C.; Desjeux, J.F.; Dallery, L.; Grivet, J.P.

    1994-01-01

    The aim of the study is to examine in-vitro and by nuclear magnetic resonance the biological pathways for the fermentation of the 1- 13 C labelled glucose (99 atoms percent) by human colon bacteria. The preparation of the bacterial suspension and the glucose degradation kinetics are presented; the NMR analysis sensitivity and quantification features are discussed and results are presented. 2 figs., 1 ref

  20. Hydration properties and phosphorous speciation in native, gelatinized and enzymatically modified potato starch analyzed by solid-state MAS NMR

    DEFF Research Database (Denmark)

    Larsen, Flemming H.; Kasprzak, Miroslaw Marek; Lærke, Helle Nygaard

    2013-01-01

    Hydration of granular, gelatinized and molecularly modified states of potato starch in terms of molecular mobility were analyzed by 13C and 31P solid-state MAS NMR. Gelatinization (GEL) tremendously reduced the immobile fraction compared to native (NA) starch granules. This effect was enhanced...... by enzyme-assisted catalytic branching with branching enzyme (BE) or combined BE and β-amylase (BB) catalyzed exo-hydrolysis. Carbons of the glycosidic α-1,6 linkages required high hydration rates before adopting uniform chemical shifts indicating solid-state disorder and poor water accessibility...... regions was only observed in NA starch. Moreover phosphorous was observed in a minor pH-insensitive form and as major phosphate in hydrated GEL and BE starches....