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Sample records for nmr spectroscopy studies

  1. Studies on metabolic regulation using NMR spectroscopy.

    Science.gov (United States)

    Bachelard, H; Badar-Goffer, R; Ben-Yoseph, O; Morris, P; Thatcher, N

    1993-01-01

    The effects of hypoxia and hypoglycaemia on cerebral metabolism and calcium have been studied using multinuclear magnetic resonance spectroscopy. 13C MRS showed that severe hypoxia did not cause any further increase in metabolic flux into lactate seen in mild hypoxia, but there was a further increase in 13C labelling of alanine and glycerol 3-phosphate. These results are discussed in terms of the ability of lactate dehydrogenase to maintain normal levels of NADH in mild hypoxia, but not in severe hypoxia. We conclude that glycerol 3-phosphate and alanine may provide novel means of monitoring severe hypoxia whereas lactate is a reliable indicator only of mild hypoxia. 19F- and 31P NMR spectroscopy showed that neither hypoxia nor hypoglycaemia alone caused any significant change in [Ca2+]i. Combined sequential insults (hypoxia, followed by hypoxia plus hypoglycaemia), or vice versa, produced a 100% increase in [Ca2+]i, whereas immediate exposure to the combined insult (hypoxia plus hypoglycaemia) resulted in a large 5-fold increase in [Ca2+]i, with severe irreversible effects on the energy state. These results are discussed in terms of metabolic adaptation to the single type of insult, which renders the tissue less vulnerable to the combined insult. The effects of this combined insult are far more severe than those caused by glutamate or NMDA, which throws doubt on the current excitoxic hypothesis of cell damage.

  2. 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

  3. Biomolecular recognition mechanisms studied by NMR spectroscopy and MD simulations

    NARCIS (Netherlands)

    Hsu, Shang-Te Danny

    2004-01-01

    This thesis describes the use of solution Nuclear Magnetic Resonance (NMR) spectroscopy and Molecular Dynamics (MD) simulations to study the mechanism of biomolecular recognition with two model systems: i) lipid II-binding lantibiotics (lanthionine-containing antibiotics) and ii) the human immunodef

  4. 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

  5. Relaxation dispersion NMR spectroscopy for the study of protein allostery.

    Science.gov (United States)

    Farber, Patrick J; Mittermaier, Anthony

    2015-06-01

    Allosteric transmission of information between distant sites in biological macromolecules often involves collective transitions between active and inactive conformations. Nuclear magnetic resonance (NMR) spectroscopy can yield detailed information on these dynamics. In particular, relaxation dispersion techniques provide structural, dynamic, and mechanistic information on conformational transitions occurring on the millisecond to microsecond timescales. In this review, we provide an overview of the theory and analysis of Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion NMR experiments and briefly describe their application to the study of allosteric dynamics in the homeodomain from the PBX transcription factor (PBX-HD). CPMG NMR data show that local folding (helix/coil) transitions in one part of PBX-HD help to communicate information between two distant binding sites. Furthermore, the combination of CPMG and other spin relaxation data show that this region can also undergo local misfolding, reminiscent of conformational ensemble models of allostery.

  6. 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

  7. Studies of Molecular Dynamics by Solid State Deuterium NMR Spectroscopy

    Science.gov (United States)

    Zhao, Baiyi

    The rotational dynamics of molecules in a number of solid systems were followed by variable temperature deuterium (^2H), nuclear magnetic resonance (NMR) spectroscopy via changes in the spectral lineshapes and spin-lattice relaxation times (T _1). First the pure solid trimethylamine-borane adduct, (CH_3)_3NBH_3, was studied. For a methyl deuterated sample, T _1 measurements yielded two T_1 minima, 6.9 ms and 4.3 ms corresponding to the slowing of methyl and trimethyl rotation, respectively, with decreasing temperature. Activation energies for methyl and trimethyl rotation, obtained from fitting the T _1 curve as a function of temperature, were 32.8 and 15.0 kJ/mol, respectively; simulations of the spectral lineshapes gave 26.6 and 18.9 kT/mol, respectively. Fitting of the ^2H T_1 curve for the borane deuterated sample gave a BH _3 rotation activation energy of 14.1 kT/mol and a ^2H quadrupolar coupling constant, chi, of 101 kHz. The activation energy for BH_3 rotation obtained from the spectral lineshape simulations gave 12.6 kT/mol. A series of deuterated organic chalcogen cations: (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, were ion exchanged into the cavities of sodium Mordenite LZ-M5 and the dynamics of these guests within the hydrated zeolite were followed by ^2H NMR. All three undergo isotropic motion above about -80 to -90^circC. Below this temperature two superimposed ^2H powder spectra appear; the broad lineshape is consistent with only methyl rotation in a hindered, coordinated site, and the other narrow lineshape is due to both methyl and trimethyl rotation in a less hindered, uncoordinated site. As the temperature is lowered the population of the lower energy coordinated site increases. Relative peak areas yield adsorption enthalpies of 6.7, 7.8 and 10.0 kJ/mol for (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, respectively. The series of methyl deuterated ammonium and phosphonium cations: (CH_3)NH_3^+ , (CH_3)_2NH^+ , (CH_3)_3NH^+ and (CH_3)_4P^+ , were

  8. 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)

  9. Annual reports on NMR spectroscopy

    CERN Document Server

    Webb, Graham A; McCarthy, M J

    1995-01-01

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

  10. Fundamentals of Protein NMR Spectroscopy

    CERN Document Server

    Rule, Gordon S

    2006-01-01

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

  11. 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......- and 2H-labelled peptides. While the solution NMR experiments were performed to determine the structure of SPF-5506-A4 and Conolysin-Mt1, the oriented solid-state NMR experiments served to derive information about the orientation of the peptides with respect to the bilayer normal in order to understand...

  12. Intramolecular hydrogen-bonding studies by NMR spectroscopy

    CERN Document Server

    Cantalapiedra, N A

    2000-01-01

    o-methoxybenzamide and N-methyl-o-methylbenzamide, using the pseudo-contact shifts calculated from the sup 1 H and sup 1 sup 3 C NMR spectra. The main conformation present in solution for o-fluorobenzamide was the one held by an intramolecular N-H...F hydrogen bond. Ab-initio calculations (at the RHF/6-31G* level) have provided additional data for the geometry of the individual molecules. A conformational equilibrium study of some nipecotic acid derivatives (3-substituted piperidines: CO sub 2 H, CO sub 2 Et, CONH sub 2 , CONHMe, CONEt sub 2) and cis-1,3-disubstituted cyclohexane derivatives (NHCOMe/CO sub 2 Me, NHCOMe/CONHMe, NH sub 2 /CO sub 2 H) has been undertaken in a variety of solvents, in order to predict the intramolecular hydrogen-bonding energies involved in the systems. The conformer populations were obtained by direct integration of proton peaks corresponding to the equatorial and axial conformations at low temperature (-80 deg), and by geometrically dependent coupling constants ( sup 3 J sub H s...

  13. Lithium substitution in strontium chlorapatite studied by solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, S.; Sairam, T. N., E-mail: sai@igcar.gov.in; Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Maji, B. K.; Jena, H. [Chemical Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2016-05-23

    Strontium Chlorapatites with various amounts of Li substitution (Sr{sub 10-x}Li{sub x}(PO{sub 4}){sub 6}Cl{sub 2-δ}) were prepared by solid state reaction method and characterized by powder XRD and solid state NMR spectroscopy. XRD reveals shortening of lattice parameters upon Li incorporation. The linewidth of {sup 31}P solid state Magic Angle Spinning NMR spectra decreases with increase in Li content within the apatite phase. This study confirms Li uptake within the apatite phase.

  14. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    Directory of Open Access Journals (Sweden)

    S. Delbaere

    2006-01-01

    is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching obtained by UV-visible spectroscopy are reported.

  15. 14N NMR Spectroscopy Study of Binding Interaction between Sodium Azide and Hydrated Fullerene

    Directory of Open Access Journals (Sweden)

    Tamar Chachibaia

    2017-04-01

    Full Text Available Our study is the first attempt to study the interaction between NaN3 and hydrated fullerenes C60 by means of a non-chemical reaction-based approach. The aim is to study deviations of signals obtained by 14N NMR spectroscopy to detect the binding interaction between sodium azide and hydrated fullerene. We considered 14N NMR spectroscopy as one of the most suitable methods for the characterization of azides to show resonance signals corresponding to the three non-equivalent nitrogen atoms. The results demonstrate that there are changes in the chemical shift positions and line-broadening, which are related to the different molar ratios of NaN3:C60 in the samples.

  16. Conformational equilibrium of phenylacetic acid and its halogenated analogues through theoretical studies, NMR and IR spectroscopy

    Science.gov (United States)

    Levandowski, Mariana N.; Rozada, Thiago C.; Melo, Ulisses Z.; Basso, Ernani A.; Fiorin, Barbara C.

    2017-03-01

    This paper presents a study on the conformational preferences of phenylacetic acid (PA) and its halogenated analogues (FPA, CPA, BPA). To clarify the effects that rule these molecules' behaviour, theoretical calculations were used, for both the isolated phase and solution, combined with nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Most conformations of phenylacetic acid and its halogenated derivatives are stabilized through the hyperconjugative effect, which rules the conformational preference. NMR analyses showed that even with the variation in medium polarity, there was no significant change in the conformation population. Infrared spectroscopy showed similar results for all compounds under study. In most spectra, two bands were found through the carbonyl deconvolution, which is in accordance with the theoretical data. It was possible to prove that variation in the nature of the substituent in the ortho position had no significant influence on the conformational equilibrium.

  17. NMR spectroscopy study of local correlations in water

    Science.gov (United States)

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Stanley, H. Eugene

    2016-12-01

    Using nuclear magnetic resonance we study the dynamics of the hydrogen bond (HB) sub-domains in bulk and emulsified water across a wide temperature range that includes the supercooled regime. We measure the proton spin-lattice T1 and spin-spin T2 relaxation times to understand the hydrophilic interactions that determine the properties of water. We use (i) the Bloembergen, Purcell, and Pound approach that focuses on a single characteristic correlation time τc, and (ii) the Powles and Hubbard approach that measures the proton rotational time τθ. We find that when the temperature is low both relaxation times are strongly correlated when the HB lifetime is long, and that when the temperature is high a decrease in the HB lifetime destroys the water clusters and decouples the dynamic modes of the system.

  18. NMR studies of metalloproteins.

    Science.gov (United States)

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

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

  19. Hyperpolarized 131Xe NMR spectroscopy

    Science.gov (United States)

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

    2011-01-01

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

  20. Structural studies of lithium zinc borohydride by neutron powder diffraction, Raman and NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ravnsbaek, D.B. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Frommen, C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Reed, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Filinchuk, Y. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Institute of Condensed Matter and Nanosciences, Universite Catholique de Louvain, 1 Place L. Pasteur, B-1348, Louvain-la-Neuve (Belgium); Sorby, M.; Hauback, B.C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Jakobsen, H.J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Book, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Besenbacher, F. [Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Skibsted, J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Jensen, T.R., E-mail: trj@chem.au.dk [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark)

    2011-09-15

    Research highlights: > Structural study of the first interpenetrated framework hydride, LiZn{sub 2}(BH{sub 4}){sub 5} > Determination of deuterium positions and revision of crystal structure by PND. > Raman spectroscopy confirms the presence of isolated [Zn{sub 2}(BD{sub 4}){sub 5}]-bar complex anions. > Determination of quadrupole coupling parameters and chemical shifts by {sup 11}B MAS NMR. - Abstract: The crystal structure of LiZn{sub 2}(BH{sub 4}){sub 5} is studied in detail using a combination of powder neutron diffraction (PND), Raman spectroscopy, and {sup 11}B MAS NMR spectroscopy on LiZn{sub 2}(BH{sub 4}){sub 5} and LiZn{sub 2}({sup 11}BD{sub 4}){sub 5}. The aim is to obtain detailed structural knowledge of the first interpenetrated framework hydride compound, LiZn{sub 2}(BD{sub 4}){sub 5} which consists of doubly interpenetrated 3D frameworks built from dinuclear complex ions [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} and lithium ions. The positions of the deuterium atoms are determined using Rietveld refinement of the PND data and the orientation of one of the four independent BD{sub 4}{sup -} groups is revised. The current data reveal that the structure of [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} is more regular than previously reported, as are also the coordinations around the Zn and Li atoms. Both Zn and Li atoms are found to coordinate to the BD{sub 4}{sup -} units via the tetrahedral edges. Some distortion of the angles within the BD{sub 4} units is observed, relative to the expected angles of 109.4 for the ideal tetrahedral coordination. Raman spectroscopy confirms bending and stretching modes from the expected terminal and bridging bidentate BH{sub 4}{sup -} and BD{sub 4}{sup -} units. The {sup 11}B MAS NMR spectrum of the satellite transitions resolves two distinct manifolds of spinning sidebands, which allows estimation of the {sup 11}B quadrupole coupling parameters and isotropic chemical shifts for the four distinct {sup 11}B sites of [Zn{sub 2}(BD

  1. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The synthesis of photochromic 3,3-di( 4 ′ -fluorophenyl-3H-benzopyrans fused to an indole moiety is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data ( λ max⁡ of colored form, colorability, and rate constant of bleaching obtained by UV-visible spectroscopy are reported.

  2. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    OpenAIRE

    S. Delbaere; J. Berthet; M. A. Salvador; Vermeersch, G.; Oliveira,M. M.

    2006-01-01

    The synthesis of photochromic 3,3-di(4′-fluorophenyl)-3H-benzopyrans fused to an indole moiety is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching) obtained by UV-visible spectroscopy are reported.

  3. Postharvest ripening study of sweet lime (Citrus limettioides) in situ by volume-localized NMR spectroscopy.

    Science.gov (United States)

    Banerjee, Abhishek; George, Christy; Bharathwaj, Sathyamoorthy; Chandrakumar, Narayanan

    2009-02-25

    Spatially resolved NMR--especially volume-localized spectroscopy (VLS)is useful in various fields including clinical diagnosis, process monitoring, etc. VLS carries high significance because of its ability to identify molecular species and hence track molecular events. This paper reports the application of VLS at 200 MHz to study the postharvest ripening of sweet lime ( Citrus limettioides ) in situ, including a comparative study of normal and acetylene-mediated ripening. Localization to a cubic voxel of 64 microL was achieved with point-resolved spectroscopy (PRESS). Glucose, sucrose, fructose, and citric acid are found to be among the main constituents in the fruit. In the natural process, the sugar to acid ratio increases with ripening. Ethanol generation is seen to occur at a faster rate in acetylene-mediated ripening. Whereas NMR imaging experiments including parametric imaging (e.g., T(1) or T(2) maps) may be employed for "macro" monitoring of processes such as these, this work demonstrates that the molecular imprint of the process may be tracked noninvasively by VLS.

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

    Science.gov (United States)

    Cavaleiro, Jose A. S.

    1987-01-01

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

  5. Enzyme dynamics from NMR spectroscopy.

    Science.gov (United States)

    Palmer, Arthur G

    2015-02-17

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

  6. A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative using NMR spectroscopy techniques.

    Science.gov (United States)

    Hamzah, Rosniza; Bakar, Mohamad Abu; Khairuddean, Melati; Mohammed, Issam Ahmed; Adnan, Rohana

    2012-09-12

    A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative was carried out using NMR spectroscopy techniques. The overlapping (1)H-NMR signals of ENR-50 at δ 1.56, 1.68-1.70, 2.06, 2.15-2.17 ppm were successfully assigned. In this work, the C=S and quaternary carbon of cyclic dithiocarbonate. All other (1)H- and (13)C-NMR chemical shifts of the derivative remain unchanged with respect to the ENR-50.

  7. 1H NMR spectroscopy-based interventional metabolic phenotyping: a cohort study of rheumatoid arthritis patients

    DEFF Research Database (Denmark)

    Lauridsen, Michael Brændgaard; Bliddal, Henning; Christensen, Robin Daniel Kjersgaard;

    2010-01-01

    1H NMR spectroscopy-based metabolic phenotyping was used to identify biomarkers in the plasma of patients with rheumatoid arthritis (RA). Forty-seven patients with RA (23 with active disease at baseline and 24 in remission) and 51 healthy subjects were evaluated during a one-year follow-up with a...

  8. Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy, a new approach to study humic material?

    Science.gov (United States)

    Knicker, Heike; Lange, Sascha; van Rossum, Barth; Oschkinat, Hartmut

    2016-04-01

    Compared to solution NMR spectroscopy, solid-state NMR spectra suffer from broad resonance lines and low resolution. This could be overcome by the use of 2-dimenstional solid-state NMR pulse sequences. Until recently, this approach has been unfeasible as a routine tool in soil chemistry, mainly because of the low NMR sensitivity of the respective samples. A possibility to circumvent those sensitivity problems represents high-field Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy (Barnes et al., 2008), allowing considerable signal enhancements (Akbey et al., 2010). This is achieved by a microwave-driven transfer of polarization from a paramagnetic center to nuclear spins. Application of DNP to MAS spectra of biological systems (frozen solutions) showed enhancements of the factor 40 to 50 (Hall et al., 1997). Enhancements of this magnitude, thus may enable the use of at least some of the 2D solid-state NMR techniques that are presently already applied for pure proteins but are difficult to apply to soil peptides in their complex matrix. After adjusting the required acquisition parameters to the system "soil organic matter", lower but still promising enhancement factors were achieved. Additional optimization was performed and allowed the acquisition of 2D 13C and 15N solid-state NMR spectra of humified 13C and 15N enriched plant residues. Within the present contribution, the first solid-state DNP NMR spectra of humic material are presented. Those data demonstrate the great potential of this approach which certainly opens new doors for a better understanding of biochemical processes in soils, sediments and water. Akbey, Ü., Franks, W.T., Linden, A., Lange, S., Griffin, R.G., van Rossum, B.-J., Oschkinat, H., 2010. Dynamic nuclear polarization of deuterated proteins. Angewandte Chemie International Edition 49, 7803-7806. Barnes, A.B., De Paëpe, G., van der Wel, P.C.A., Hu, K.N., Joo, C.G., Bajaj, V.S., Mak-Jurkauskas, M.L., Sirigiri, J.R., Herzfeld, J

  9. TG/DTG, FT-ICR Mass Spectrometry, and NMR Spectroscopy Study of Heavy Fuel Oil

    KAUST Repository

    Elbaz, Ayman M.

    2015-11-12

    There is an increasing interest in the comprehensive study of heavy fuel oil (HFO) due to its growing use in furnaces, boilers, marines, and recently in gas turbines. In this work, the thermal combustion characteristics and chemical composition of HFO were investigated using a range of techniques. Thermogravimetric analysis (TGA) was conducted to study the nonisothermal HFO combustion behavior. Chemical characterization of HFO was accomplished using various standard methods in addition to direct infusion atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (APCI-FTICR MS), high resolution 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear multiple bond correlation (HMBC) spectroscopy. By analyzing thermogravimetry and differential thermogravimetry (TG/DTG) results, three different reaction regions were identified in the combustion of HFO with air, specifically, low temperature oxidation region (LTO), fuel deposition (FD), and high temperature oxidation (HTO) region. At the high end of the LTO region, a mass transfer resistance (skin effect) was evident. Kinetic analysis in LTO and HTO regions was conducted using two different kinetic models to calculate the apparent activation energy. In both models, HTO activation energies are higher than those for LTO. The FT-ICR MS technique resolved thousands of aromatic and sulfur containing compounds in the HFO sample and provided compositional details for individual molecules of three major class species. The major classes of compounds included species with one sulfur atom (S1), with two sulfur atoms (S2), and purely hydrocarbons (HC). The DBE (double bond equivalent) abundance plots established for S1 and HC provided additional information on their distributions in the HFO sample. The 1H NMR and 13C NMR results revealed that nearly 59% of the 1H nuclei were distributed as paraffinic CH2 and 5% were in aromatic groups. Nearly 21% of 13C nuclei were

  10. Bacterial expression and isotope labeling of AIMP1/p43 codosome protein for structural studies by multidimensional NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    Vorobyova N. V.

    2015-04-01

    Full Text Available AIMP1/p43 protein is a structural component of multisynthetase complex (codosome in eukaryotes, which reveals both tRNA binding and cytokine activities. Aim. Bacterial expression and purification of isotopically-labeled recombinant AIMP1/p43 protein in E. coli cells for studying its solution structure by multidimensional NMR spectroscopy. Methods. AIMP1/p43 protein was expressed in E. coli BL21(DE3pLysE cells on M9 minimal medium with 15N isotope labeling and purified by metal-chelated chromatography. Heteronuclear 2D 1H-15N NMR experiments were performed in solution at 293 K on Agilent DDR2 800 NMR spectrometer. Results. The AIMP1/p43 protein was obtained in uniformly 15N-labeled form as an NMR sample. A high dispersion of resonance signals in the 2D 1H-15N HSQC NMR spectra confirmed the presence of its compact 3D protein structure. The NMR spectrum of AIMP1/p43 demonstrated a high signal-to-noise ratio and sufficient stability to acquire other multidimensional NMR data sets for determination of the structure of AIMP1/p43 protein in solution. Conclusions. The 15N-labeled AIMP1/p43 protein was stable for 4–7 days, which makes possible acquiring the critical NMR experimental data for detailed structural analysis in solution. Our data on the initial NMR spectra indicated the presence of some additional signals in comparison with the NMR spectrum of EMAP II which could be assigned to amino acids of the N-terminal α-helical fragment of AIMP1/p43.

  11. STRUCTURAL STUDIES OF BIOMATERIALS USING DOUBLE-QUANTUM SOLID-STATE NMR SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Drobny, Gary P.; Long, J. R.; Karlsson, T.; Shaw, Wendy J.; Popham, Jennifer M.; Oyler, N.; Bower, Paula M.; Stringer, J.; Gregory, D.; Mehta, M.; Stayton, Patrick S.

    2004-10-31

    Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composites technologies. Here, we describe both the theory and practice of double-quantum solid-stateNMR(ssNMR) structure-determination techniques, as they are used to determine the secondary structures of surface-adsorbed peptides and proteins. In particular, we have used ssNMR dipolar techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxyapatite (HAP) surface. Here, we also review NMR data on peptides designed to adsorb from aqueous solutions onto highly porous hydrophobic surfaces with specific helical secondary structures. The adsorption or covalent attachment of biological macromolecules onto polymer materials to improve their biocompatibility has been pursued using a variety of approaches, but key to understanding their efficacy is the verification of the structure and dynamics of the immobilized biomolecules using double-quantum ssNMR spectroscopy.

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

    Science.gov (United States)

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

    2011-03-01

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

  13. A strategy for co-translational folding studies of ribosome-bound nascent chain complexes using NMR spectroscopy.

    Science.gov (United States)

    Cassaignau, Anaïs M E; Launay, Hélène M M; Karyadi, Maria-Evangelia; Wang, Xiaolin; Waudby, Christopher A; Deckert, Annika; Robertson, Amy L; Christodoulou, John; Cabrita, Lisa D

    2016-08-01

    During biosynthesis on the ribosome, an elongating nascent polypeptide chain can begin to fold, in a process that is central to all living systems. Detailed structural studies of co-translational protein folding are now beginning to emerge; such studies were previously limited, at least in part, by the inherently dynamic nature of emerging nascent chains, which precluded most structural techniques. NMR spectroscopy is able to provide atomic-resolution information for ribosome-nascent chain complexes (RNCs), but it requires large quantities (≥10 mg) of homogeneous, isotopically labeled RNCs. Further challenges include limited sample working concentration and stability of the RNC sample (which contribute to weak NMR signals) and resonance broadening caused by attachment to the large (2.4-MDa) ribosomal complex. Here, we present a strategy to generate isotopically labeled RNCs in Escherichia coli that are suitable for NMR studies. Uniform translational arrest of the nascent chains is achieved using a stalling motif, and isotopically labeled RNCs are produced at high yield using high-cell-density E. coli growth conditions. Homogeneous RNCs are isolated by combining metal affinity chromatography (to isolate ribosome-bound species) with sucrose density centrifugation (to recover intact 70S monosomes). Sensitivity-optimized NMR spectroscopy is then applied to the RNCs, combined with a suite of parallel NMR and biochemical analyses to cross-validate their integrity, including RNC-optimized NMR diffusion measurements to report on ribosome attachment in situ. Comparative NMR studies of RNCs with the analogous isolated proteins permit a high-resolution description of the structure and dynamics of a nascent chain during its progressive biosynthesis on the ribosome.

  14. An introduction to biological NMR spectroscopy.

    Science.gov (United States)

    Marion, Dominique

    2013-11-01

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

  15. Thermodynamic Study on the Protonation Reactions of Glyphosate in Aqueous Solution: Potentiometry, Calorimetry and NMR spectroscopy.

    Science.gov (United States)

    Liu, Bijun; Dong, Lan; Yu, Qianhong; Li, Xingliang; Wu, Fengchang; Tan, Zhaoyi; Luo, Shunzhong

    2016-03-10

    Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject (J. Phys. Chem. A 2015, 119, 5241-5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7-8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.

  16. Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study.

    Science.gov (United States)

    Ferro, Monica; Castiglione, Franca; Punta, Carlo; Melone, Lucio; Panzeri, Walter; Rossi, Barbara; Trotta, Francesco; Mele, Andrea

    2016-08-15

    The chemical cross-linking of β-cyclodextrin (β-CD) with ethylenediaminetetraacetic dianhydride (EDTA) led to branched polymers referred to as cyclodextrin nanosponges (CDNSEDTA). Two different preparations are described with 1:4 and 1:8 CD-EDTA molar ratios. The corresponding cross-linked polymers were contacted with 0.27 M aqueous solution of ibuprofen sodium salt (IP) leading to homogeneous, colorless, drug loaded hydrogels. The systems were characterized by high resolution magic angle spinning (HR-MAS) NMR spectroscopy. Pulsed field gradient spin echo (PGSE) NMR spectroscopy was used to determine the mean square displacement (MSD) of IP inside the polymeric gel at different observation times td. The data were further processed in order to study the time dependence of MSD: MSD = f(td). The proposed methodology is useful to characterize the different diffusion regimes that, in principle, the solute may experience inside the hydrogel, namely normal or anomalous diffusion. The full protocols including the polymer preparation and purification, the obtainment of drug-loaded hydrogels, the NMR sample preparation, the measurement of MSD by HR-MAS NMR spectroscopy and the final data processing to achieve the time dependence of MSD are here reported and discussed. The presented experiments represent a paradigmatic case and the data are discussed in terms of innovative approach to the characterization of the transport properties of an encapsulated guest within a polymeric host of potential application for drug delivery.

  17. Prostate Cancer Diagnosis: experimental and Clinical Studies With HRMAS NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stenman, Katarina

    2011-07-01

    approach using 1D and 2D high-resolution magic angle spinning (HRMAS) NMR spectroscopy combined with histopathology on intact prostatectomy specimens was evaluated in this research project. The non-destructive nature of HRMAS NMR enables spectroscopic analysis of intact tissue samples with consecutive histological examinations under light microscope. Metabolomics aids in the unraveling and the discovery of organ-specific endogenous metabolites that have the potential to be reliable indicators of organ function and viability, extrinsic and intrinsic perturbations, as well as valuable markers for treatment response. The results may, therefore, be applied clinically to characterize an organ by utilizing bio-markers that have the capacity to distinguish between disease and health. The aim was to characterize the human and the rat prostate in terms of its intermediary metabolism, which is shown here to differ between species and anatomical regions. Furthermore, the aim is to seek the verification of HRMAS NMR derived metabolites which are known to be a part of the prostate metabolome such as, citrate, choline, and the polyamines which were performed, but also the identification of metabolites not previously identified as part of the local prostate metabolism, such as Omega-6, which was detected in tumors. The extended aim was to elucidate novel bio-markers with clinical potential. In this study, the common phyto-nutrient, inositol, which appears to possess protective properties, was identified as being a potentially important PCa bio-marker for the distinction between the more indolent Gleason score 6 and the more aggressive Gleason score 7 in non-malignant prostate tissues with tumors elsewhere in the organ. Further studies in this area of PCa research are therefore warranted

  18. NMR Spectroscopy and Its Value: A Primer

    Science.gov (United States)

    Veeraraghavan, Sudha

    2008-01-01

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

  19. NMR Spectroscopy and Its Value: A Primer

    Science.gov (United States)

    Veeraraghavan, Sudha

    2008-01-01

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

  20. Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, (2)H NMR, and (31)P NMR spectroscopy.

    Science.gov (United States)

    Pötzschner, B; Mohamed, F; Bächer, C; Wagner, E; Lichtinger, A; Bock, D; Kreger, K; Schmidt, H-W; Rössler, E A

    2017-04-28

    We investigate the secondary (β-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of (2)H and (31)P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a β-relaxation (β1 (SBC) and β2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the β-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical (31)P NMR echo spectra of the β2-process, very similar spectral features are observed for the (deuterated) SBC component by (2)H NMR, in addition to its "own" β1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τβ2 are the same. Furthermore, T1(T) of TPP in the temperature region of the β2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the β-process introduced by one component are essentially independent of the second component. Finally, at cTPP

  1. Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, 2H NMR, and 31P NMR spectroscopy

    Science.gov (United States)

    Pötzschner, B.; Mohamed, F.; Bächer, C.; Wagner, E.; Lichtinger, A.; Bock, D.; Kreger, K.; Schmidt, H.-W.; Rössler, E. A.

    2017-04-01

    We investigate the secondary (β-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of 2H and 31P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a β-relaxation (β1 (SBC) and β2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the β-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical 31P NMR echo spectra of the β2-process, very similar spectral features are observed for the (deuterated) SBC component by 2H NMR, in addition to its "own" β1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τβ2 are the same. Furthermore, T1(T) of TPP in the temperature region of the β2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the β-process introduced by one component are essentially independent of the second component. Finally, at cTPP ≤ 20% one

  2. Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

    Science.gov (United States)

    Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

    2011-02-17

    In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

  3. Metabolic profiling for studying chemotype variations in Withania somnifera (L.) Dunal fruits using GC-MS and NMR spectroscopy.

    Science.gov (United States)

    Bhatia, Anil; Bharti, Santosh K; Tewari, Shri K; Sidhu, Om P; Roy, Raja

    2013-09-01

    Withania somnifera (L.) Dunal (Solanaceae), commonly known as Ashwagandha, is one of the most valued Indian medicinal plant with several pharmaceutical and nutraceutical applications. Metabolic profiling was performed by GC-MS and NMR spectroscopy on the fruits obtained from four chemotypes of W. somnifera. A combination of (1)H NMR spectroscopy and GC-MS identified 82 chemically diverse metabolites consisting of organic acids, fatty acids, aliphatic and aromatic amino acids, polyols, sugars, sterols, tocopherols, phenolic acids and withanamides in the fruits of W. somnifera. The range of metabolites identified by GC-MS and NMR of W. somnifera fruits showed various known and unknown metabolites. The primary and secondary metabolites observed in this study represent MVA, DOXP, shikimic acid and phenylpropanoid biosynthetic metabolic pathways. Squalene and tocopherol have been rated as the most potent naturally occurring compounds with antioxidant properties. These compounds have been identified by us for the first time in the fruits of W. somnifera. Multivariate principal component analysis (PCA) on GC-MS and NMR data revealed clear distinctions in the primary and secondary metabolites among the chemotypes. The variation in the metabolite concentration among different chemotypes of the fruits of W. somnifera suggest that specific chemovars can be used to obtain substantial amounts of bioactive ingredients for use as potential pharmacological and nutraceuticals agents.

  4. Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

    Science.gov (United States)

    Kamal, Ghulam Mustafa; Wang, Xiaohua; Bin Yuan; Wang, Jie; Sun, Peng; Zhang, Xu; Liu, Maili

    2016-09-01

    Soy sauce a well known seasoning all over the world, especially in Asia, is available in global market in a wide range of types based on its purpose and the processing methods. Its composition varies with respect to the fermentation processes and addition of additives, preservatives and flavor enhancers. A comprehensive (1)H NMR based study regarding the metabonomic variations of soy sauce to differentiate among different types of soy sauce available on the global market has been limited due to the complexity of the mixture. In present study, (13)C NMR spectroscopy coupled with multivariate statistical data analysis like principle component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) was applied to investigate metabonomic variations among different types of soy sauce, namely super light, super dark, red cooking and mushroom soy sauce. The main additives in soy sauce like glutamate, sucrose and glucose were easily distinguished and quantified using (13)C NMR spectroscopy which were otherwise difficult to be assigned and quantified due to serious signal overlaps in (1)H NMR spectra. The significantly higher concentration of sucrose in dark, red cooking and mushroom flavored soy sauce can directly be linked to the addition of caramel in soy sauce. Similarly, significantly higher level of glutamate in super light as compared to super dark and mushroom flavored soy sauce may come from the addition of monosodium glutamate. The study highlights the potentiality of (13)C NMR based metabonomics coupled with multivariate statistical data analysis in differentiating between the types of soy sauce on the basis of level of additives, raw materials and fermentation procedures.

  5. Study of cyclic quaternary ammonium bromides by B3LYP calculations, NMR and FTIR spectroscopies.

    Science.gov (United States)

    Brycki, Bogumił; Szulc, Adrianna; Kowalczyk, Iwona

    2010-08-16

    N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas phase. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants confirm the optimized geometry.

  6. Study of Cyclic Quaternary Ammonium Bromides by B3LYP Calculations, NMR and FTIR Spectroscopies

    Directory of Open Access Journals (Sweden)

    Iwona Kowalczyk

    2010-08-01

    Full Text Available N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas phase. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants confirm the optimized geometry.

  7. Structural studies of proteins by paramagnetic solid-state NMR spectroscopy

    Science.gov (United States)

    Jaroniec, Christopher P.

    2015-04-01

    Paramagnetism-based nuclear pseudocontact shifts and spin relaxation enhancements contain a wealth of information in solid-state NMR spectra about electron-nucleus distances on the ∼20 Å length scale, far beyond that normally probed through measurements of nuclear dipolar couplings. Such data are especially vital in the context of structural studies of proteins and other biological molecules that suffer from a sparse number of experimentally-accessible atomic distances constraining their three-dimensional fold or intermolecular interactions. This perspective provides a brief overview of the recent developments and applications of paramagnetic magic-angle spinning NMR to biological systems, with primary focus on the investigations of metalloproteins and natively diamagnetic proteins modified with covalent paramagnetic tags.

  8. Structural studies of proteins by paramagnetic solid-state NMR spectroscopy

    Science.gov (United States)

    Jaroniec, Christopher P.

    2015-01-01

    Paramagnetism-based nuclear pseudocontact shifts and spin relaxation enhancements contain a wealth of information in solid-state NMR spectra about electron-nucleus distances on the ~20 Å length scale, far beyond that normally probed through measurements of nuclear dipolar couplings. Such data are especially vital in the context of structural studies of proteins and other biological molecules that suffer from a sparse number of experimentally-accessible atomic distances constraining their three-dimensional fold or intermolecular interactions. This perspective provides a brief overview of the recent developments and applications of paramagnetic magic-angle spinning NMR to biological systems, with primary focus on the investigations of metalloproteins and natively diamagnetic proteins modified with covalent paramagnetic tags. PMID:25797004

  9. 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.

  10. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

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

  11. Conformational Study of 8-C-glucosyl-prunetin by Dynamic NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin,isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-I" gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.

  12. Conformational Study of 8—C—glucosyl—prunetin by Dynamic NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    PeiChengZHANG; YingHongWANG; 等

    2002-01-01

    By means of variable temperature NMR spectra,conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C(sp3)-C(sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1″ gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.

  13. A Guided Inquiry Approach to NMR Spectroscopy

    Science.gov (United States)

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

    1998-04-01

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

  14. Non-polymeric asymmetric binary glass-formers. I. Main relaxations studied by dielectric, (2)H NMR, and (31)P NMR spectroscopy.

    Science.gov (United States)

    Pötzschner, B; Mohamed, F; Bächer, C; Wagner, E; Lichtinger, A; Minikejew, R; Kreger, K; Schmidt, H-W; Rössler, E A

    2017-04-28

    In Paper I of this series of two papers we study the main relaxations of a binary glass former made of the low-Tg component tripropyl phosphate (TPP, Tg = 134 K) and of a specially synthesized (deuterated) spirobichroman derivative (SBC, Tg = 356 K) as the non-polymeric high-Tg component for the full concentration range. A large Tg contrast of the neat components is put into effect. Dielectric spectroscopy and different techniques of (2)H nuclear magnetic resonance (NMR) as well as of (31)P NMR spectroscopy allow to selectively probe the dynamics of the components. For all concentrations, two well separated liquid-like processes are identified. The faster α2-process associated with the low-Tg component TPP shows pronounced dynamic heterogeneities reflected by quasi-logarithmic correlation functions at low TPP concentrations. The slower α1-process involves the reorientation of the high-Tg component SBC. Its correlation function is Kohlrausch-like as in neat glass formers. The corresponding time constants and consequently their glass transition temperatures Tg1 and Tg2 differ more the lower the TPP concentration is. Plasticizer and anti-plasticizer effect, respectively, is observed. At low temperatures a situation arises that the TPP molecules isotropically reorient in an arrested SBC matrix (Tg2 < T < Tg1). At T < Tg2 the liquid-like reorientation of TPP gets arrested too. We find indications that a fraction of the TPP molecule takes part in the slower α1-process of the high-Tg component. All the features known from polymer-plasticizer systems are rediscovered in this non-polymeric highly asymmetric binary mixture. In Paper II [B. Pötzschner et al., J. Chem. Phys. 146, 164504 (2017)] we study the secondary (β-) relaxations of the mixtures.

  15. Non-polymeric asymmetric binary glass-formers. I. Main relaxations studied by dielectric, 2H NMR, and 31P NMR spectroscopy

    Science.gov (United States)

    Pötzschner, B.; Mohamed, F.; Bächer, C.; Wagner, E.; Lichtinger, A.; Minikejew, R.; Kreger, K.; Schmidt, H.-W.; Rössler, E. A.

    2017-04-01

    In Paper I of this series of two papers we study the main relaxations of a binary glass former made of the low-Tg component tripropyl phosphate (TPP, Tg = 134 K) and of a specially synthesized (deuterated) spirobichroman derivative (SBC, Tg = 356 K) as the non-polymeric high-Tg component for the full concentration range. A large Tg contrast of the neat components is put into effect. Dielectric spectroscopy and different techniques of 2H nuclear magnetic resonance (NMR) as well as of 31P NMR spectroscopy allow to selectively probe the dynamics of the components. For all concentrations, two well separated liquid-like processes are identified. The faster α2-process associated with the low-Tg component TPP shows pronounced dynamic heterogeneities reflected by quasi-logarithmic correlation functions at low TPP concentrations. The slower α1-process involves the reorientation of the high-Tg component SBC. Its correlation function is Kohlrausch-like as in neat glass formers. The corresponding time constants and consequently their glass transition temperatures Tg1 and Tg2 differ more the lower the TPP concentration is. Plasticizer and anti-plasticizer effect, respectively, is observed. At low temperatures a situation arises that the TPP molecules isotropically reorient in an arrested SBC matrix (Tg2 < T < Tg1). At T < Tg2 the liquid-like reorientation of TPP gets arrested too. We find indications that a fraction of the TPP molecule takes part in the slower α1-process of the high-Tg component. All the features known from polymer-plasticizer systems are rediscovered in this non-polymeric highly asymmetric binary mixture. In Paper II [B. Pötzschner et al., J. Chem. Phys. 146, 164504 (2017)] we study the secondary (β-) relaxations of the mixtures.

  16. Reconsidering the activation entropy for anomerization of glucose and mannose in water studied by NMR spectroscopy

    Science.gov (United States)

    Kosaka, Ami; Aida, Misako; Katsumoto, Yukiteru

    2015-08-01

    The anomerization of monosaccharides is a very important process to understand how their stereoisomers are stabilized in aqueous solutions. For glucose and mannose, it has been known that α- and β-anomers of hexopyranose exist as the major components. In order to examine the anomerization pathway for glucose and mannose in aqueous solutions, it is indispensable to determine the thermodynamic parameters such as the activation energy, the activation Gibbs free energy (ΔG‡), enthalpy (ΔH‡), and entropy (ΔS‡). Although several research groups reported these quantities in aqueous solution, they have still been controversial especially for ΔS‡. In this paper, we employ 1H NMR spectroscopy for monitoring the population of both α- and β-anomers of glucose and mannose. The contribution of ΔS‡ to ΔG‡ for glucose in water is estimated to be ca. 30%, while that for mannose is 8.0%. The large difference in ΔS‡ suggests that the anomerization pathway is not the same for glucose and mannose.

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

    Science.gov (United States)

    Alonso, David E.; Warren, Steven E.

    2005-01-01

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

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

    Science.gov (United States)

    Alonso, David E.; Warren, Steven E.

    2005-01-01

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

  19. Ionic Liquid-Solute Interactions Studied by 2D NOE NMR Spectroscopy.

    Science.gov (United States)

    Khatun, Sufia; Castner, Edward W

    2015-07-23

    Intermolecular interactions between a Ru(2+)(bpy)3 solute and the anions and cations of four different ionic liquids (ILs) are investigated by 2D NMR nuclear Overhauser effect (NOE) techniques, including {(1)H-(19)F} HOESY and {(1)H-(1)H} ROESY. Four ILs are studied, each having the same bis(trifluoromethylsulfonyl)amide anion in common. Two of the ILs have aliphatic 1-alkyl-1-methylpyrrolidinium cations, while the other two ILs have aromatic 1-alkyl-3-methylimidazolium cations. ILs with both shorter (butyl) and longer (octyl or decyl) cationic alkyl substituents are studied. NOE NMR results suggest that the local environment of IL anions and cations near the Ru(2+)(bpy)3 solute is rather different from the bulk IL structure. The solute-anion and solute-cation interactions are significantly different both for ILs with short vs long alkyl tails and for ILs with aliphatic vs aromatic cation polar head groups. In particular, the solute-anion interactions are observed to be about 3 times stronger for the cations with shorter alkyl tails relative to the ILs with longer alkyl tails. The Ru(2+)(bpy)3 solute interacts with both the polar head and the nonpolar tail groups of the 1-butyl-1-methylpyrrolidinium cation but only with the nonpolar tail groups of the 1-decyl-1-methylpyrrolidinium cation.

  20. Variability of cork from Portuguese Quercus suber studied by solid-state (13)C-NMR and FTIR spectroscopies.

    Science.gov (United States)

    Lopes, M H; Barros, A S; Pascoal Neto, C; Rutledge, D; Delgadillo, I; Gil, A M

    2001-01-01

    A new approach is presented for the study of the variability of Portuguese reproduction cork using solid-state (13)C-NMR spectroscopy and photoacoustic (PAS) FTIR (FTIR-PAS) spectroscopy combined with chemometrics. Cork samples were collected from 12 different geographical sites, and their (13)C-cross-polarization with magic angle spinning (CP/MAS) and FTIR spectra were registered. A large spectral variability among the cork samples was detected by principal component analysis and found to relate to the suberin and carbohydrate contents. This variability was independent of the sample geographical origin but significantly dependent on the cork quality, thus enabling the distinction of cork samples according to the latter property. The suberin content of the cork samples was predicted using multivariate regression models based on the (13)C-NMR and FTIR spectra of the samples as reported previously. Finally, the relationship between the variability of the (13)C-CP/MAS spectra with that of the FTIR-PAS spectra was studied by outer product analysis. This type of multivariate analysis enabled a clear correlation to be established between the peaks assigned to suberin and carbohydrate in the FTIR spectrum and those appearing in the (13)C-CP/MAS spectra.

  1. 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...

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

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    Millions of people around the world take antimicrobial drugs every day to fight off bacterial infections. However, the microbes are starting to fight back and to develop resistance towards conventional antibiotics, posing a major challenge in the future. Therefore, there is a need for exploring...... the opportunities for alternative drugs that cannot be overcome by the bacteria. In this context, cytolytic peptides are being investigated and designed to target cell membranes of microbes specifically. In the search for information about the structure and dynamics of membrane-active peptides, three highly...... to characterize different properties of these peptides. Owing to the membrane-active nature of all three, the peptides were studied in model membranes including isotropic bicelles, magnetically aligned bilayers and mechanically aligned bilayers, employing a diverse set of NMR experiments on unlabeled and 15N...

  3. Conformational studies of vasopressin and mesotocin using NMR spectroscopy and molecular modelling methods. Part I: Studies in water.

    Science.gov (United States)

    Sikorska, Emilia; Rodziewicz-Motowidło, Sylwia

    2008-01-01

    Arginine vasopressin (AVP) and mesotocin (MT) belong to the neurohypophyseal hormone family. The former plays a very important role in the control of urine concentration and the blood pressure in mammals, whereas the latter stimulates uterine concentration and initiates birth in amphibians, marsupials, wallabies, birds, and fishes. Analysis of their 3D structure could be helpful for understanding the evolutionary relationship between all vasopressin- and oxytocin-like hormones. In addition, it allows design of new analogs with appropriate biological activity for humans and animals. In this paper, we present the conformational studies of AVP and MT, under the aqueous conditions. In our investigations, we used 2D NMR spectroscopy and time-averaged molecular dynamics calculations in explicit water. Our studies have shown that both peptides, despite displaying a high sequence homology, differ from each other with regard to the three-dimensional structure. They are in conformational equilibrium as a result of the cis/trans isomerization across the Cys(6)-Pro(7) peptide bond. Both peptides form beta-turns in their cyclic part, wherein the C-terminal fragment of MT is bent, whereas that of AVP is extended.

  4. Dynamic Processes in Prochiral Solvating Agents (pro-CSAs Studied by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jan Labuta

    2014-05-01

    Full Text Available Several dynamic processes, including tautomerism and macrocyclic inversion, in 1H-NMR prochiral solvating agents (pro-CSAs are investigated. Various features of pro-CSA, including modes of interaction for complex formation, stoichiometry, binding strength and temperature effects were compared for three representative pro-CSA molecules. Structural effects of conjugated tetrapyrrole pro-CSA on the mechanism of enantiomeric excess determination are also discussed. Detailed analysis of species (complexes and dynamic processes occurring in solution and their 1H-NMR spectral manifestations at various temperatures is presented.

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

    Energy Technology Data Exchange (ETDEWEB)

    Matwiyoff, N.A.

    1983-01-01

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

  6. NMR spectroscopy: a tool for conformational analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  7. A Study of Quantum Error Correction by Geometric Algebra and Liquid-State NMR Spectroscopy

    CERN Document Server

    Sharf, Y; Somaroo, S S; Havel, T F; Knill, E H; Laflamme, R; Sharf, Yehuda; Cory, David G.; Somaroo, Shyamal S.; Havel, Timothy F.; Knill, Emanuel; Laflamme, Raymond

    2000-01-01

    Quantum error correcting codes enable the information contained in a quantum state to be protected from decoherence due to external perturbations. Applied to NMR, quantum coding does not alter normal relaxation, but rather converts the state of a ``data'' spin into multiple quantum coherences involving additional ancilla spins. These multiple quantum coherences relax at differing rates, thus permitting the original state of the data to be approximately reconstructed by mixing them together in an appropriate fashion. This paper describes the operation of a simple, three-bit quantum code in the product operator formalism, and uses geometric algebra methods to obtain the error-corrected decay curve in the presence of arbitrary correlations in the external random fields. These predictions are confirmed in both the totally correlated and uncorrelated cases by liquid-state NMR experiments on 13C-labeled alanine, using gradient-diffusion methods to implement these idealized decoherence models. Quantum error correcti...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-15

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    This paper outlines the advantages and disadvantages of using high throughput NMR metabolomics for nutritional studies with emphasis on the workflow and data analytical methods for generation of new knowledge. The paper describes one-by-one the major research activities in the interdisciplinary...... structures for multivariate pattern recognition methods and (3) NMR for providing a unique fingerprint of the lipoprotein status of the subject. For the first time in history, by combining NMR spectroscopy and chemometrics we are able to perform inductive nutritional research as a complement to the deductive...

  10. 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...

  11. Applications of NMR spectroscopy to systems biochemistry.

    Science.gov (United States)

    Fan, Teresa W-M; Lane, Andrew N

    2016-02-01

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

  12. Human calf muscular metabolism study with a home-made ergometer using 31P NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Peynsaert, J.; Achten, E.; Claeys, E. [Ghent University Hospital (Belgium); Rousseaux, M. [Ghent University Hospital (Belgium). Dept. of Sport Medicine

    1995-12-01

    Phosphorus-31 NMR measurements were performed to examine the variations in the concentration of phosphate metabolites in calf muscle during exercise. Therefore, volunteers, installed in the supine position, were asked to push repetitively on the pedal of a home-made ergometer. The produced work and the changes in phosphorus containing metabolites were measured continuously. Correlations were made between the inorganic phosphate/phosphocreatine ratio and the cumulative work and between the intracellular pH and the cumulative work. The exercise protocol could be changed interactively with respect to the imposed initial pressure, the maximum pressure, the pressure increase per level and the time a certain level was held. The whole experiment could be graphically followed on-line. In the first stadium, the in vitro reproducibility of the ergometer was tested for different protocols. These tests revealed that, though the deviation in produced work was markedly the highest at high working pressures, the relative error never exceeded 3%. Consequently, the ex vitro reproducibility of the data was examined with the equipment placed in the scanner. Generally, same conclusions could be derived. In a next stage, the work will be synchronized with the biochemical data. Extreme precautions will be taken to examine each volunteer every time under the same physical and psychological conditions.

  13. Hexameric Capsules Studied by Magic Angle Spinning Solid-State NMR Spectroscopy: Identifying Solvent Molecules in Pyrogallol[4]arene Capsules.

    Science.gov (United States)

    Avram, Liat; Goldbourt, Amir; Cohen, Yoram

    2016-01-18

    Powders of pyrogallol[4]arene hexamers were produced by evaporation from organic solvents and were studied, for the first time, by magic angle spinning solid-state NMR (MAS ssNMR). Evaporation selectively removed non-encapsulated solvent molecules leaving stable hexameric capsules encapsulating solvent molecules. After exposure of the powder to solvent vapors, (1)H/(13)C heteronuclear correlation MAS ssNMR experiments were used to assign the signals of the external and encapsulated solvent molecules. The formed capsules were stable for months and the process of solvent encapsulation was reversible. According to the ssNMR experiments, the encapsulated solvent molecules occupy different sites and those sites differ in their mobility. The presented approach paves the way for studying guest exchange, guest affinity, and gas storage in hexamers of this type in the solid state.

  14. NMR studies of metalloproteins

    OpenAIRE

    Li, H; H. Sun

    2011-01-01

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

  15. Membrane protein-lipid interactions in mixed micelles studied by NMR spectroscopy with the use of paramagnetic reagents.

    Science.gov (United States)

    Hilty, Christian; Wider, Gerhard; Fernández, César; Wüthrich, Kurt

    2004-04-02

    For solution NMR studies of the structure and function of membrane proteins, these macromolecules have to be reconstituted and solubilized in detergent micelles. Detailed characterization of the mixed detergent/protein micelles is then of key importance to validate the results from such studies, and to evaluate how faithfully the natural environment of the protein in the biological membrane is mimicked by the micelle. In this paper, a selection of paramagnetic probes with different physicochemical properties are used to characterize the 60 kDa mixed micelles consisting of about 90 molecules of the detergent dihexanoylphosphatidylcholine (DHPC) and one molecule of the Escherichia coli outer-membrane protein X (OmpX), which had previously been extensively studied by solution NMR techniques. The observation of highly selective relaxation effects on the NMR spectra of OmpX and DHPC from a water-soluble relaxation agent and from nitroxide spin labels attached to lipophilic molecules, confirmed data obtained previously with more complex NMR studies of the diamagnetic OmpX/DHPC system, and yielded additional novel insights into the protein-detergent interactions in the mixed micelles. The application of paramagnetic probes to the well-characterized OmpX/DHPC system indicates that such probes should be widely applicable as an efficient support of NMR studies of the topology of mixed membrane protein-detergent micelles.

  16. Applications of Solid-State NMR Spectroscopy for the Study of Lipid Membranes with Polyphilic Guest (MacroMolecules

    Directory of Open Access Journals (Sweden)

    Ruth Bärenwald

    2016-12-01

    Full Text Available The incorporation of polymers or smaller complex molecules into lipid membranes allows for property modifications or the introduction of new functional elements. The corresponding molecular-scale details, such as changes in dynamics or features of potential supramolecular structures, can be studied by a variety of solid-state NMR techniques. Here, we review various approaches to characterizing the structure and dynamics of the guest molecules as well as the lipid phase structure and dynamics by different high-resolution magic-angle spinning proton and 13C NMR experiments as well as static 31P NMR experiments. Special emphasis is placed upon the incorporation of novel synthetic polyphilic molecules such as shape-persistent T- and X-shaped molecules as well as di- and tri-block copolymers. Most of the systems studied feature dynamic heterogeneities, for instance those arising from the coexistence of different phases; possibilities for a quantitative assessment are of particular concern.

  17. Recovering Invisible Signals by Two-Field NMR Spectroscopy.

    Science.gov (United States)

    Cousin, Samuel F; Kadeřávek, Pavel; Haddou, Baptiste; Charlier, Cyril; Marquardsen, Thorsten; Tyburn, Jean-Max; Bovier, Pierre-Alain; Engelke, Frank; Maas, Werner; Bodenhausen, Geoffrey; Pelupessy, Philippe; Ferrage, Fabien

    2016-08-16

    Nuclear magnetic resonance (NMR) studies have benefited tremendously from the steady increase in the strength of magnetic fields. Spectacular improvements in both sensitivity and resolution have enabled the investigation of molecular systems of rising complexity. At very high fields, this progress may be jeopardized by line broadening, which is due to chemical exchange or relaxation by chemical shift anisotropy. In this work, we introduce a two-field NMR spectrometer designed for both excitation and observation of nuclear spins in two distinct magnetic fields in a single experiment. NMR spectra of several small molecules as well as a protein were obtained, with two dimensions acquired at vastly different magnetic fields. Resonances of exchanging groups that are broadened beyond recognition at high field can be sharpened to narrow peaks in the low-field dimension. Two-field NMR spectroscopy enables the measurement of chemical shifts at optimal fields and the study of molecular systems that suffer from internal dynamics, and opens new avenues for NMR spectroscopy at very high magnetic fields.

  18. UV-visible-DAD and 1H-NMR spectroscopy data fusion for studying the photodegradation process of azo-dyes using MCR-ALS.

    Science.gov (United States)

    Fernández, Cristina; Pilar Callao, M; Larrechi, M Soledad

    2013-12-15

    The photodegradation process of three azo-dyes - Acid Orange 61, Acid Red 97 and Acid Brown 425 - was monitored simultaneously by ultraviolet-visible spectroscopy with diode array detector (UV-vis-DAD) and (1)H-nuclear magnetic resonance ((1)H-NMR). Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to obtain the concentration and spectral profile of the chemical compounds involved in the process. The analysis of the H-NMR data suggests there are more intermediate compounds than those obtained with the UV-vis-DAD data. The fusion of UV-vis-DAD and the (1)H-NMR signal before the multivariate analysis provides better results than when only one of the two detector signals was used. It was concluded that three degradation products were present in the medium when the three azo-dyes had practically degraded. This study is the first application of UV-vis-DAD and (1)H-NMR spectroscopy data fusion in this field and illustrates its potential as a quick method for evaluating the evolution of the azo-dye photodegradation process. © 2013 Elsevier B.V. All rights reserved.

  19. Solid-State 13C NMR Spectroscopy Applied to the Study of Carbon Blacks and Carbon Deposits Obtained by Plasma Pyrolysis of Natural Gas

    Directory of Open Access Journals (Sweden)

    Jair C. C. Freitas

    2016-01-01

    Full Text Available Solid-state 13C nuclear magnetic resonance (NMR spectroscopy was used in this work to analyze the physical and chemical properties of plasma blacks and carbon deposits produced by thermal cracking of natural gas using different types of plasma reactors. In a typical configuration with a double-chamber reactor, N2 or Ar was injected as plasma working gas in the first chamber and natural gas was injected in the second chamber, inside the arc column. The solid residue was collected at different points throughout the plasma apparatus and analyzed by 13C solid-state NMR spectroscopy, using either cross polarization (CP or direct polarization (DP, combined with magic angle spinning (MAS. The 13C CP/MAS NMR spectra of a number of plasma blacks produced in the N2 plasma reactor showed two resonance bands, broadly identified as associated with aromatic and aliphatic groups, with indication of the presence of oxygen- and nitrogen-containing groups in the aliphatic region of the spectrum. In contrast to DP experiments, only a small fraction of 13C nuclei in the plasma blacks are effectively cross-polarized from nearby 1H nuclei and are thus observed in spectra recorded with CP. 13C NMR spectra are thus useful to distinguish between different types of carbon species in plasma blacks and allow a selective study of groups spatially close to hydrogen in the material.

  20. Cis-trans isomerisation of azobenzenes studied by laser-coupled NMR spectroscopy and DFT calculations.

    Science.gov (United States)

    Wazzan, Nuha A; Richardson, Patricia R; Jones, Anita C

    2010-07-30

    In a combined experimental and computational study of a group of para-substituted azobenzenes, the effects of substituents and solvent on the kinetics of thermal cis-to-trans isomerisation have been examined and the success of DFT calculations in predicting kinetic parameters assessed. Mono-substituted species are predicted to isomerise by inversion in both non-polar and polar solvent, whereas for push-pull azobenzenes the mechanism is predicted to change from inversion to rotation on going from non-polar to polar solvent. Computed free energies of activation qualitatively reproduce experimental trends but do not quantitatively predict the kinetics of cis-trans isomerisation. The polarisable continuum model of solvation fails to predict the experimentally observed influence of solvent on the entropy of activation.

  1. Kinetic study of littorine rearrangement in Datura innoxia hairy roots by (13)C NMR spectroscopy.

    Science.gov (United States)

    Lanoue, Arnaud; Boitel-Conti, Michèle; Portais, Jean-Charles; Laberche, Jean-Claude; Barbotin, Jean-Noël; Christen, Philippe; Sangwan-Norreel, Brigitte

    2002-08-01

    The kinetics of tropane alkaloid biosynthesis, particularly the isomerization of littorine into hyoscyamine, were studied by analyzing the kinetics of carbon-13 ((13)C) in metabolites of Datura innoxia hairy root cultures fed with labeled tropoyl moiety precursors. Both littorine and hyoscyamine were the major alkaloids accumulated, while scopolamine was never detected. Feeding root cultures with (RS)-phenyl[1,3-(13)C(2)]lactic acid led to (13)C spin-spin coupling detected on C-1' and C-2' of the hyoscyamine skeleton, which validated the intramolecular rearrangement of littorine into hyoscyamine. Label from phenyl[1-(13)C]alanine or (RS)-phenyl[1,3-(13)C(2)]lactic acid was incorporated at higher levels in littorine than in hyoscyamine. Initially, the apparent hyoscyamine biosynthesized rate (v(app)()hyo = 0.9 micromol (13)C.flask(-1).d(-1)) was lower than littorine formation (v(app)()litto = 1.8 micromol (13)C.flask(-1).d(-1)), suggesting that the isomerization reaction could be rate limiting. The results obtained for the kinetics of littorine biosynthesis were in agreement with the role of this compound as a direct precursor of hyoscyamine biosynthesis.

  2. A study of transition-metal organometallic complexes combining 35Cl solid-state NMR spectroscopy and 35Cl NQR spectroscopy and first-principles DFT calculations.

    Science.gov (United States)

    Johnston, Karen E; O'Keefe, Christopher A; Gauvin, Régis M; Trébosc, Julien; Delevoye, Laurent; Amoureux, Jean-Paul; Popoff, Nicolas; Taoufik, Mostafa; Oudatchin, Konstantin; Schurko, Robert W

    2013-09-09

    A series of transition-metal organometallic complexes with commonly occurring metal-chlorine bonding motifs were characterized using (35)Cl solid-state NMR (SSNMR) spectroscopy, (35)Cl nuclear quadrupole resonance (NQR) spectroscopy, and first-principles density functional theory (DFT) calculations of NMR interaction tensors. Static (35)Cl ultra-wideline NMR spectra were acquired in a piecewise manner at standard (9.4 T) and high (21.1 T) magnetic field strengths using the WURST-QCPMG pulse sequence. The (35)Cl electric field gradient (EFG) and chemical shielding (CS) tensor parameters were readily extracted from analytical simulations of the spectra; in particular, the quadrupolar parameters are shown to be very sensitive to structural differences, and can easily differentiate between chlorine atoms in bridging and terminal bonding environments. (35)Cl NQR spectra were acquired for many of the complexes, which aided in resolving structurally similar, yet crystallographically distinct and magnetically inequivalent chlorine sites, and with the interpretation and assignment of (35)Cl SSNMR spectra. (35)Cl EFG tensors obtained from first-principles DFT calculations are consistently in good agreement with experiment, highlighting the importance of using a combined approach of theoretical and experimental methods for structural characterization. Finally, a preliminary example of a (35)Cl SSNMR spectrum of a transition-metal species (TiCl4) diluted and supported on non-porous silica is presented. The combination of (35)Cl SSNMR and (35)Cl NQR spectroscopy and DFT calculations is shown to be a promising and simple methodology for the characterization of all manner of chlorine-containing transition-metal complexes, in pure, impure bulk and supported forms.

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

    Science.gov (United States)

    Mills, Nancy S.; Shanklin, Michael

    2011-01-01

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

  4. Evidence for altered metabolic pathways during environmental stress: (1)H-NMR spectroscopy based metabolomics and clinical studies on subjects of sea-voyage and Antarctic-stay.

    Science.gov (United States)

    Yadav, Anand Prakash; Chaturvedi, Shubhra; Mishra, Kamla Prasad; Pal, Sunil; Ganju, Lilly; Singh, Shashi Bala

    2014-08-01

    The Antarctic context is an analogue of space travel, with close similarity in ambience of extreme climate, isolation, constrained living spaces, disrupted sleep cycles, and environmental stress. The present study examined the impact of the harsh habitat of Antarctica on human physiology and its metabolic pathways, by analyzing human serum samples, using (1)H-NMR spectroscopy for identification of metabolites; and quantifying other physiological and clinical parameters for correlation between expression data and metabolite data. Sera from seven adult males (of median age 36years) who participated in this study, from the 28th Indian Expeditionary group to the Antarctica station Maitri, were collected in chronological sequence. These included: i) baseline control; ii) during ship journey; iii) at Antarctica, in the months of March, May, August and November; to enable study of temporal evolution of monitored physiological states. 29 metabolites in serum were identified from the 400MHz (1)H-NMR spectra. Out of these, 19 metabolites showed significant variations in levels, during the ship journey and the stay at Maitri, compared to the base-line levels. Further biochemical analysis also supported these results, indicating that the ship journey, and the long-term Antarctic exposure, affected kidney and liver functioning. Our metabolite data highlights for the first time the effect of environmental stress on the patho-physiology of the human system. Multivariate analysis tools were employed for this metabonomics study, using (1)H-NMR spectroscopy.

  5. Effect of genetic and phenotypic factors on the composition of commercial marmande type tomatoes studied through HRMAS NMR spectroscopy.

    Science.gov (United States)

    Iglesias, María José; García López, Jesús; Collados Luján, Juan Fernando; López Ortiz, Fernando; Bojórquez Pereznieto, Humberto; Toresano, Fernando; Camacho, Francisco

    2014-01-01

    The effects of genetic, technological and environmental factors on the chemical composition of four marmande type tomato varieties have been investigated. The study is based on the analysis of (1)H HRMAS NMR spectra of tomato purée using a combination of partial least squares (PLS) and assigned signal analysis (ASA). In agreement with genetic, morphological and taste characteristics of the tomatoes studied, the analysis of the NMR data allows two groups of samples to be differentiated. The type of culture and climatic conditions can reduce the compositional differences. The extension of the compositional changes produced by climatic conditions is variety-depend. Neither grafting nor perlite affect significantly the relative content of primary metabolites. This was not the case for tomatoes grown using the pure hydroponic production system based on the recirculation of nutrient solution, New Growing System NGS®, which seems to be an effective agricultural approach to improve tomato quality.

  6. Dermostatin A and B: chromatography, structural and configurational studies using HPLC, CCD, 13C (125 MHz) and 1H (500 MHz) NMR spectroscopy.

    Science.gov (United States)

    Swamy, M B; Sastry, M K; Nanda, R K

    1994-01-01

    HPLC of crude Dermostatin indicated presence of three pairs of components. Hence, attempts were made to purify Dermostatin. Purification of crude Dermostatin has been carried out using column chromatography and counter current distribution methods. Each of these fractions were tested for activity. The major fraction which showed greater activity was taken for the preparation of Dermostatin nona-acetate. Structural characterisation of Dermostatin nona-acetate has been carried out using UV-visible spectroscopy in different solvents to obtain the characteristic spectrum of a carbonyl conjugated hexaene at room temperature. Structural and configurational studies of Dermostatin nona-acetate using 500 MHz 1H NMR and 125 MHz 13C NMR has been used in the assignment of various functional groups in Dermostatin A and B as well as to provide corroboration to the earlier structural elucidation.

  7. Lanthanide paramagnetic probes for NMR spectroscopic studies of fast molecular conformational dynamics and temperature control. Effective six-site proton exchange in 18-crown-6 by exchange spectroscopy.

    Science.gov (United States)

    Babailov, Sergey P

    2012-02-06

    (1)H and (13)C NMR measurements are reported for the CDCl(3) and CD(2)Cl(2) solutions of [La(18-crown-6)(NO(3))(3)] (I), [Pr(18-crown-6) (NO(3))(3)] (II), [Ce(18-crown-6)(NO(3))(3)] (III), and [Nd(18-crown-6)(NO(3))(3)] (IV) complexes. Temperature dependencies of the (1)H NMR spectra of paramagnetic II-IV have been analyzed using the dynamic NMR (DNMR) methods for six-site exchange. Two types of conformational dynamic processes were identified (the first one is conditioned by interconversion of complex enantiomeric forms and pseudorotation of a macrocycle molecule upon the C(2) symmetry axis; the second one is conditioned by macrocycle molecule inversion). Application of exchange spectroscopy (2D-EXSY) of DNMR for investigation of this dynamic system (II-IV) simplifies the assignment of the NMR signals and represents the first experimental study of multisite exchange. In the present work, the methodology of paramagnetic 4f (Ce, Pr, and Nd) probe applications for the study of free-energy, enthalpy, and entropy changes in chemical exchange processes, as well as the advantages of this method in a comparison with DNMR studies of diamagnetic substances, is discussed. In particular, as a result of paramagnetic chemical shifts in 4f complexes, the range of measurable rate constants expands considerably compared to the analogous range in diamagnetic compounds. Coordination compounds investigated in the paper represent new types of thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solution.

  8. Applied NMR spectroscopy for chemists and life scientists

    CERN Document Server

    Zerbe, Oliver

    2013-01-01

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

  9. Conformation of Novel Azo-Dyes Bearing End-Capped Oligo(ethylene glycol) Studied by UV-vis and NMR Spectroscopy.

    Science.gov (United States)

    Kouvatas, Cassandre; Baille, Wilms E; Ortíz-Palacios, Jesús; Aguilar-Ortíz, Edgar; Rivera, Ernesto; Zhu, X X

    2015-09-17

    Two novel azo-dyes bearing an end-capped oligo(ethylene glycol) chain were synthesized and then studied by UV-visible and NMR spectroscopy. For both azobenzenes, the end-capped oligo(ethylene glycol) segment is on the para position of the first phenyl ring. On the second phenyl ring, a methoxy group is added on the para position for one azo-dye and no substitution group on the other, which made them electronically a push-push and a push system, respectively. The presence of the methoxy group changes significantly the absorption and the photoisomerization behaviors and results in a much less intense absorbance for the trans isomer and a shift from 350 to 360 nm. In the kinetic studies the azobenzene bearing a methoxy group shows a zero-order and a first-order kinetics as a function of the time scale of the study as well as an aggregation phenomenon. This azo-dye in different solvents has been studied by (1)H NMR and pulsed gradient NMR experiments to understand the effects of the photoisomerization and the aggregation on the self-diffusion of these molecules in solutions.

  10. {sup 19}F-labeling of the adenine H2-site to study large RNAs by NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sochor, F. [Johann Wolfgang Goethe-University Frankfurt, Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ) (Germany); Silvers, R. [Massachusetts Institute of Technology, Department of Chemistry, Francis Bitter Magnet Laboratory (United States); Müller, D.; Richter, C.; Fürtig, B., E-mail: fuertig@nmr.uni-frankfurt.de; Schwalbe, H., E-mail: schwalbe@nmr.uni-frankfurt.de [Johann Wolfgang Goethe-University Frankfurt, Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ) (Germany)

    2016-01-15

    In comparison to proteins and protein complexes, the size of RNA amenable to NMR studies is limited despite the development of new isotopic labeling strategies including deuteration and ligation of differentially labeled RNAs. Due to the restricted chemical shift dispersion in only four different nucleotides spectral resolution remains limited in larger RNAs. Labeling RNAs with the NMR-active nucleus {sup 19}F has previously been introduced for small RNAs up to 40 nucleotides (nt). In the presented work, we study the natural occurring RNA aptamer domain of the guanine-sensing riboswitch comprising 73 nucleotides from Bacillus subtilis. The work includes protocols for improved in vitro transcription of 2-fluoroadenosine-5′-triphosphat (2F-ATP) using the mutant P266L of the T7 RNA polymerase. Our NMR analysis shows that the secondary and tertiary structure of the riboswitch is fully maintained and that the specific binding of the cognate ligand hypoxanthine is not impaired by the introduction of the {sup 19}F isotope. The thermal stability of the {sup 19}F-labeled riboswitch is not altered compared to the unmodified sequence, but local base pair stabilities, as measured by hydrogen exchange experiments, are modulated. The characteristic change in the chemical shift of the imino resonances detected in a {sup 1}H,{sup 15}N-HSQC allow the identification of Watson–Crick base paired uridine signals and the {sup 19}F resonances can be used as reporters for tertiary and secondary structure transitions, confirming the potential of {sup 19}F-labeling even for sizeable RNAs in the range of 70 nucleotides.

  11. The Doppler effect in NMR spectroscopy.

    Science.gov (United States)

    Guéron, Maurice

    2003-02-01

    An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

  12. Structural Characterization of Intrinsically Disordered Proteins by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Peter Tompa

    2013-09-01

    Full Text Available Recent advances in NMR methodology and techniques allow the structural investigation of biomolecules of increasing size with atomic resolution. NMR spectroscopy is especially well-suited for the study of intrinsically disordered proteins (IDPs and intrinsically disordered regions (IDRs which are in general highly flexible and do not have a well-defined secondary or tertiary structure under functional conditions. In the last decade, the important role of IDPs in many essential cellular processes has become more evident as the lack of a stable tertiary structure of many protagonists in signal transduction, transcription regulation and cell-cycle regulation has been discovered. The growing demand for structural data of IDPs required the development and adaption of methods such as 13C-direct detected experiments, paramagnetic relaxation enhancements (PREs or residual dipolar couplings (RDCs for the study of ‘unstructured’ molecules in vitro and in-cell. The information obtained by NMR can be processed with novel computational tools to generate conformational ensembles that visualize the conformations IDPs sample under functional conditions. Here, we address NMR experiments and strategies that enable the generation of detailed structural models of IDPs.

  13. Two dimensional fluoride ion conductor RbSn {2}F {5} studied by impedance spectroscopy and {19}F, {119}Sn, and {87}Rb NMR

    Science.gov (United States)

    Yamada, K.; Ahmad, M. M.; Ogiso, Y.; Okuda, T.; Chikami, J.; Miehe, G.; Ehrenberg, H.; Fuess, H.

    2004-07-01

    RbSn2F5 is a two-dimensional fluoride ion conductor. It undergoes a first-order phase transition to a superionic state at 368 K. The structure of the low temperature phase has been determined from the Rietveld analysis of the X-ray powder diffraction. The dynamic properties of the fluoride ions in RbSn2F5 have been studied by impedance spectroscopy and solid state NMR. The dc ionic conductivity of this sample shows an abrupt increase at the phase transition temperature. We have obtained the hopping frequency and the concentration of the charge carriers (F- ions) at different temperatures from the analysis of the conductivity spectra using Almond-West formalism. The estimated values of the charge carriers’ concentration agree well with that determined from the structure and were found to be independent of temperature. The relatively small value of the power-law exponent, n ≈ 0.55, supports the two-dimensional property of the investigated material. Furthermore, 19F NMR with simulation has suggested the diffusive motions of the fluoride ions between different sites. In contrast, 119Sn and 87Rb NMR spectra below 250 K supported the intrinsic disordered nature due to the random distribution of the fluoride ion vacancies.

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

    Science.gov (United States)

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

    2011-08-07

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

  16. 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...

  17. Conformational studies on 2-substituted ethanesulfonates in aqueous solution by 1H NMR spectroscopy and DFT calculations

    Science.gov (United States)

    Musio, Roberta; Sciacovelli, Oronzo

    2009-09-01

    The conformation of some 2-substituted sodium ethanesulfonates exerting biological functions, XCH 2CH 2SO 3Na (X = S -, Br, Cl, OH, NH 2, SH), has been investigated in aqueous solution by 1H NMR spectroscopy. Potential energy curves for rotation about the C-C bond have been calculated at DFT level of theory (B3LYP/6-311++G(2d,p)) in vacuum and in water (by IEF-PCM method). As concerning dianionic coenzyme M (X = S -), 2-bromo- and 2-chloroethanesulfonate, in vacuum the torsional potential curves and the variations of atomic charges and geometric parameters suggest that electrostatic and steric repulsions between the substituent X and -SO3- moiety determine the preference for anti conformer. In isethionate (X = OH), anionic taurine (X = NH 2), and coenzyme M (X = SH), the formation of an intramolecular hydrogen bond stabilizes also gauche-like conformers and the torsional potential curves exhibit two minima. According to Natural Bond Orbital analysis, hydrogen bond can be ascribed to electron transfer from two oxygen lone-pairs of the -SO3- moiety to the antibonding Y-H orbital of the substituent X. In all the compounds examined, hyperconjugative interactions tend to stabilize the gauche conformers with respect to the anti one. This means that conformational preferences in vacuum are determined by a counterbalancing of electrostatic, steric, and hyperconjugative interactions. Calculations in vacuum are not in agreement with the experimental conformational behaviour of the compounds examined. In order to reproduce the experimental results at least qualitatively, solvent effect must be introduced.

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

    Directory of Open Access Journals (Sweden)

    S. Khushu

    1993-07-01

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

  19. Exploring abiotic stress on asynchronous protein metabolism in single kernels of wheat studied by NMR spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Winning, H.; Viereck, N.; Wollenweber, B.

    2009-01-01

    at terminal spikelet, during grain-filling or at both stages. Principal component trajectories of the total protein content and the protein fractions of flour as well as the H-1 NMR spectra of single wheat kernels, wheat flour, and wheat methanol extracts were analysed to elucidate the metabolic development...... during grain-filling. The results from both the H-1 NMR spectra of methanol extracts and the H-1 HR-MAS NMR of single kernels showed that a single drought event during the generative stage had as strong an influence on protein metabolism as two consecutive events of drought. By contrast, a drought event...... indicating that protein metabolism is influenced by multiple drought events, the H-1 NMR spectra of the methanol extracts of flour from mature grains revealed that the amount of fumaric acid is particularly sensitive to water deficits....

  20. All-atom Molecular Dynamics Simulationsand NMR Spectroscopy Study on Interactions and Structures in N-Glycylglycine Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Rong Zhang; Wen-juan Wu; Jing-man Huang; Xin Meng

    2011-01-01

    All-atom molecular dynamics (MD) simulation and the NMR spectra are used to investigate the interactions in N-glycylglycine aqueous solution.Different types of atoms exhibit different capability in forming hydrogen bonds by the radial distribution function analysis.Some typical dominant aggregates are found in different types of hydrogen bonds by the statistical hydrogen-bonding network.Moreover,temperature-dependent NMR are used to compare with the results of the MD simulations.The chemical shifts of the three hydrogen atoms all decrease with the temperature increasing which reveals that the hydrogen bonds are dominant in the glycylglycine aqueous solution.And the NMR results show agreement with the MD simulations.All-atom MD simulations and NMR spectra are successful in revealing the structures and interactions in the N-glycylglycine-water mixtures.

  1. Unscrambling micro-solvation of -COOH and -NH groups in neat dimethyl sulfoxide: insights from (1)H-NMR spectroscopy and computational studies.

    Science.gov (United States)

    Takis, Panteleimon G; Papavasileiou, Konstantinos D; Peristeras, Loukas D; Boulougouris, Georgios C; Melissas, Vasilios S; Troganis, Anastassios N

    2017-05-31

    Dimethyl sulfoxide (DMSO) has a significant, multi-faceted role in medicine, pharmacy, and biology as well as in biophysical chemistry and catalysis. Its physical properties and impact on biomolecular structures still attract major scientific interest, especially the interactions of DMSO with biomolecular functional groups. In the present study, we shed light on the "isolated" carboxylic (-COOH) and amide (-NH) interactions in neat DMSO via(1)H NMR studies along with extensive theoretical approaches, i.e. molecular dynamics (MD) simulations, density functional theory (DFT), and ab initio calculations, applied on model compounds (i.e. acetic and benzoic acid, ethyl acetamidocyanoacetate). Both experimental and theoretical results show excellent agreement, thereby permitting the calculation of the association constants between the studied compounds and DMSO molecules. Our coupled MD simulations, DFT and ab initio calculations, and NMR spectroscopy results indicated that complex formation is entropically driven and DMSO molecules undergo multiple strong interactions with the studied molecules, particularly with the -COOH groups. The combined experimental and theoretical techniques unraveled the interactions of DMSO with the most abundant functional groups of peptides (i.e. peptide bonds, side chain and terminal carboxyl groups) in high detail, providing significant insights on the underlying thermodynamics driving these interactions. Moreover, the developed methodology for the analysis of the simulation results could serve as a template for future thermodynamic and kinetic studies of similar systems.

  2. 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…

  3. Facing and Overcoming Sensitivity Challenges in Biomolecular NMR Spectroscopy

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, Jan Henrik; Boebinger, Gregory S.; Comment, Arnaud

    2015-01-01

    enhance the sensitivity of solid‐ and liquid‐state experiments. While substantial advances have been made in all these areas, numerous challenges remain in the quest of endowing NMR spectroscopy with the sensitivity that has characterized forms of spectroscopies based on electrical or optical measurements....... These challenges, and the ways by which scientists and engineers are striving to solve them, are also addressed....

  4. 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…

  5. Spectroscopy studies on Schiff base N,N‧-bis(salicylidene)-1,2-phenylenediamine by NMR, infrared, Raman and DFT calculations

    Science.gov (United States)

    de Toledo, T. A.; Pizani, P. S.; da Silva, L. E.; Teixeira, A. M. R.; Freire, P. T. C.

    2015-10-01

    N,N‧-bis(salicylidene)-1,2-phenylenediamine, also known as Salophen, is a Schiff base which crystallizes in monoclinic structure and space group P21/c, with four molecules per unit cell. It has been intensely studied in last decades because of its excellent properties with many potential applications. In the present study, the structural and vibrational properties of the Salophen were investigated combining scanning electronic microscopy (SEM), Raman, infrared, nuclear magnetic resonance (NMR) spectroscopy as experimental techniques and theoretical calculation based on density functional theory (DFT). The interpretation of the vibrational modes was carried out by means of potential energy distribution (PED). The theoretical results are in good agreement with experimental ones.

  6. Report on neptunium speciation by NMR and optical spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Tait, C.D.; Palmer, P.D.; Ekberg, S.A.; Clark, D.L.

    1995-11-01

    Hydrolysis and carbonate complexation reactions were examined for NpO{sub 2}{sup 2+} and NpO{sub 2}{sup +} ions by a variety of techniques including potentiometric titration, UV-Vis-NIR and NMR spectroscopy. The equilibrium constant for the reaction 3NpO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} + 3H{sup +} {rightleftharpoons} (NpO{sub 2}){sub 3}(CO{sub 3}){sub 6}{sup 6{minus}} + 3HCO{sub 3}{sup {minus}} was determined to be logK = 19.7 ({plus_minus} 0.8) (I = 2.5 m). {sup 17}O NMR spectroscopy of NpO{sub 2}{sup n+} ions (n = 1,2) reveals a readily observable {sup 17}O resonance for n = 2, but not for n = 1. The first hydrolysis constant for NpO{sub 2}{sup +} was studied as a function of temperature, and the functional form for the temperature-dependent equilibrium constant for the reaction written as NpO{sub 2}{sup +} + H{sub 2}O {rightleftharpoons} NpO{sub 2}OH + H{sup +} was found to be logK = 2.28 {minus} 3780/T, where T is in {degree}K. Finally, the temperature dependence of neptunium(V) carbonate complexation constants was studied. For the first carbonate complexation constant, the appropriate functional form was found to be log{beta}{sub 01} = 1.47 + 786/T.

  7. Oxidative stress-induced metabolic changes in mouse C2C12 myotubes studied with high-resolution 13C, 1H, and 31P NMR spectroscopy

    DEFF Research Database (Denmark)

    Straadt, Ida K; Young, Jette F; Petersen, Bent O;

    2010-01-01

    In this study, stress in relation to slaughter was investigated in a model system by the use of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy for elucidating changes in the metabolites in C2C12 myotubes exposed to H(2)O(2)-induced stress. Oxidative stress resulted in lower...... to lower levels of the unlabeled ((12)C) lactate were identified in the (1)H spectra after stress exposure. These data indicate an increase in de novo synthesis of alanine, concomitant with a release of lactate from the myotubes to the medium at oxidative stress conditions. The changes in the metabolite...... levels of several metabolites, mainly amino acids; however, higher levels of alanine were apparent in the (13)C spectra after incubation with [(13)C(1)]glucose. In the (13)C spectra [(13)C(3)]lactate tended to increase after exposure to increasing concentrations of H(2)O(2); conversely, a tendency...

  8. A straightforward implementation of in situ solution electrochemical ¹³C NMR spectroscopy for studying reactions on commercial electrocatalysts: ethanol oxidation.

    Science.gov (United States)

    Huang, L; Sorte, E G; Sun, S-G; Tong, Y Y J

    2015-05-11

    Identifying and quantifying electrocatalytic-reaction-generated solution species, be they reaction intermediates or products, are highly desirable in terms of understanding the associated reaction mechanisms. We report herein a straightforward implementation of in situ solution electrochemical (13)C NMR spectroscopy for the first time that enables in situ studies of reactions on commercial fuel-cell electrocatalysts (Pt and PtRu blacks). Using ethanol oxidation reaction (EOR) as a working example, we discovered that (1) the complete oxidation of ethanol to CO2 only took place dominantly at the very beginning of a potentiostatic chronoamperometric (CA) measurement and (2) the PtRu had a much higher activity in catalysing oxygen insertion reaction that leads to acetic acid.

  9. Covariance NMR spectroscopy by singular value decomposition.

    Science.gov (United States)

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

    2004-12-01

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

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

    Science.gov (United States)

    Mills, Nancy S.

    1998-06-01

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

  11. Lithium ion micrometer diffusion in a garnet-type cubic Li7La3Zr2O12 (LLZO) studied using 7Li NMR spectroscopy

    Science.gov (United States)

    Hayamizu, Kikuko; Seki, Shiro; Haishi, Tomoyuki

    2017-01-01

    Mobile lithium ions in a cubic garnet Li7La3Zr2O12 (Al-stabilized) were studied using 7Li NMR spectroscopy for membrane and powder samples, the latter of which was ground from the membrane. Lithium diffusion in a micrometer space was measured using the pulsed-gradient spin-echo 7Li NMR method between 70 and 130 °C. When the observation time (Δ ) was shorter than 20 ms, the echo attenuation showed diffusive diffraction patterns, indicating that the Li+ diffusing space is not free but restricted. For longer Δ, the values of apparent diffusion constant (Dapparent) became gradually smaller to approach an equilibrated value (close to a tracer diffusion constant). In addition, the Dapparent depends on the pulse field gradient strength (g) and became smaller as g became larger. These experimental results suggest that the lithium ions diffuse through Li+ pathways surrounded by stationary anions and lithium ions, and are affected by collisions and diffractions. One-dimensional profiles of the membrane sample of thickness 0.5 mm were observed from 65 to 110 °C and the area intensity, as well as the lithium occurrence near the surface, increased with the increase in temperature. The temperature-dependent area intensity showed a correspondence to the number of Li+ carrier ions estimated from the ionic conductivity and the equilibrated diffusion constant through the Nernst-Einstein relationship.

  12. Study of the contact charge transfer behavior between cryptophanes (A and E) and fullerene by absorption, fluorescence and {sup 1}H NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Caihong; Shen Weili; Fan Ruying; Zhang Guomei; Shangguan Lingzhi; Chao Jianbin; Shuang Shaomin [Research Center of Environmental Science and Engineering, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Dong Chuan, E-mail: dc@sxu.edu.cn [Research Center of Environmental Science and Engineering, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Choi, Martin M.F., E-mail: mfchoi@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2009-09-14

    A group of novel cage-like compounds cryptophanes A and E were synthesized from vanillin by a three-step method. The intermolecular interaction between cryptophanes (A and E) and fullerene (C{sub 60}) was investigated in detail by absorption, fluorescence and {sup 1}H NMR spectroscopy. The absorption of C{sub 60} at 410-650 nm decreased in the presence of cryptophanes A or E. The decrease in absorption intensity was proportional to the concentration of cryptophanes A or E. On the other hand, the fluorescence intensity of cryptophanes A or E decreased and the emission maxima were blue-shifted with the increase in C{sub 60} concentration. These results suggest that contact charge transfer (CCT) complexes can be formed from C{sub 60} with cryptophanes A or E. In addition, the electrochemical behavior of cryptophanes (A and E) and C{sub 60} was studied by cyclic voltammetry. The redox currents of cryptophanes (A and E) decreased and the peak potentials were shifted on addition of C{sub 60}. The changes in the chemical shifts ({Delta}{delta}) of aromatic protons of cryptophanes (A and E) in their NMR spectra further support that CCT complexes were formed with cryptophanes as the electron donors and C{sub 60} as the electron acceptor.

  13. Lithium ion micrometer diffusion in a garnet-type cubic Li7La3Zr2O12 (LLZO) studied using (7)Li NMR spectroscopy.

    Science.gov (United States)

    Hayamizu, Kikuko; Seki, Shiro; Haishi, Tomoyuki

    2017-01-14

    Mobile lithium ions in a cubic garnet Li7La3Zr2O12 (Al-stabilized) were studied using (7)Li NMR spectroscopy for membrane and powder samples, the latter of which was ground from the membrane. Lithium diffusion in a micrometer space was measured using the pulsed-gradient spin-echo (7)Li NMR method between 70 and 130 °C. When the observation time (Δ) was shorter than 20 ms, the echo attenuation showed diffusive diffraction patterns, indicating that the Li(+) diffusing space is not free but restricted. For longer Δ, the values of apparent diffusion constant (Dapparent) became gradually smaller to approach an equilibrated value (close to a tracer diffusion constant). In addition, the Dapparent depends on the pulse field gradient strength (g) and became smaller as g became larger. These experimental results suggest that the lithium ions diffuse through Li(+) pathways surrounded by stationary anions and lithium ions, and are affected by collisions and diffractions. One-dimensional profiles of the membrane sample of thickness 0.5 mm were observed from 65 to 110 °C and the area intensity, as well as the lithium occurrence near the surface, increased with the increase in temperature. The temperature-dependent area intensity showed a correspondence to the number of Li(+) carrier ions estimated from the ionic conductivity and the equilibrated diffusion constant through the Nernst-Einstein relationship.

  14. Studies of the Active Sites for Methane Dehydroaromatization Using Ultrahigh-Field Solid-State Mo95 NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Z.; Kwak, Ja Hun; Wang, Yong; Peden, Charles HF; Zheng, Heng; Ma, Ding; Bao, Xinhe

    2009-01-26

    Abstract It is found that the spin-lattice relaxation time, T1, corresponding to the surface exchanged molybdenum species in Mo/HZSM-5 catalysts is short, i.e., less than about 100ms at 21.1 T while the value of T1 for the crystallite MoO3 molecules is longer, i.e., about 30 s. Such a difference, more than two orders in magnitude, is utilized to differentiate the exchanged Mo species from the agglomerate MoO3 in Mo/HZSM-5 catalyst. An approximately linear correlation between the amount of exchanged species and the aromatics formation rate is obtained. This result significantly strengthens our prior conclusion that the exchanged Mo species are the active centers for the methane dehydroaromatization reaction on Mo/HZSM-5 catalysts (J. Am. Chem. Soc. 2008, 130, 3722-3723). Our results also suggest that one exchanged Mo atom anchors on two ion exchange sites and the exchanged Mo species on catalysts are possibly monomeric. Analyzing the linshapes obtained from both the 95Mo MAS and the static spectra indicates that the exchanged sites are heterogeneous, resulting in a significantly broadened MAS spectrum and essentially a featureless but nearly symmetric static lineshape for the exchanged Mo species. Furthermore, for crystallite MoO3 powder sample, the parameters related to the electric-field-gradient (EFG) tensor, the chemical shift anisotropy (CSA) and the three Euler angles required to align the CSA principal axis system with the quadrupolar principal axis system are determined by analyzing both the 95Mo MAS and the static spectra obtained at ultra-high field of 21.1 T. The new results obtained from this study on crystallite MoO3 powders should help to clarify some of the contradictions in prior literature reports from other groups. Key words: 95Mo NMR, MAS, relaxation, surface exchanged species, HZSM-5, electric-field-gradient (EFG), chemical shift anisotropy (CSA), active centers.

  15. Analyzing protein-ligand interactions by dynamic NMR spectroscopy.

    Science.gov (United States)

    Mittermaier, Anthony; Meneses, Erick

    2013-01-01

    Nuclear magnetic resonance (NMR) spectroscopy can provide detailed information on protein-ligand interactions that is inaccessible using other biophysical techniques. This chapter focuses on NMR-based approaches for extracting affinity and rate constants for weakly binding transient protein complexes with lifetimes of less than about a second. Several pulse sequences and analytical techniques are discussed, including line-shape simulations, spin-echo relaxation dispersion methods (CPMG), and magnetization exchange (EXSY) experiments.

  16. Temperature-induced transitions in disordered proteins probed by NMR spectroscopy

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Poulsen, Flemming Martin; Kragelund, Birthe Brandt

    2012-01-01

    Intrinsically disordered proteins are abundant in nature and perform many important physiological functions. Multidimensional NMR spectroscopy has been crucial for the understanding of the conformational properties of disordered proteins and is increasingly used to probe their conformational...... ensembles. Compared to folded proteins, disordered proteins are more malleable and more easily perturbed by environmental factors. Accordingly, the experimental conditions and especially the temperature modify the structural and functional properties of disordered proteins. NMR spectroscopy allows analysis...... of temperature-induced structural changes at residue resolution using secondary chemical shift analysis, paramagnetic relaxation enhancement, and residual dipolar couplings. This chapter discusses practical aspects of NMR studies of temperature-induced structural changes in disordered proteins....

  17. Room temperature chiral discrimination in paramagnetic NMR spectroscopy

    CERN Document Server

    Soncini, Alessandro

    2016-01-01

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

  18. NMR Studies of 3-Acylcamphor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  19. Quantitation of Compounds in Wine Using (1)H NMR Spectroscopy: Description of the Method and Collaborative Study.

    Science.gov (United States)

    Godelmann, Rolf; Kost, Christian; Patz, Claus-Dieter; Ristow, Reinhard; Wachter, Helmut

    2016-09-01

    To examine whether NMR analysis is a suitable method for the quantitative determination of wine components, an international collaborative trial was organized to evaluate the method according to the international regulations and guidelines of the German Institute for Standardization/International Organization for Standardization, AOAC INTERNATIONAL, the International Union of Pure and Applied Chemistry, and the International Organization of Vine and Wine. Sugars such as glucose; acids such as malic, acetic, fumaric, and shikimic acids (the latter two as minor components); and sorbic acid, a preservative, were selected for the exemplary quantitative determination of substances in wine. Selection criteria for the examination of sample material included different NMR spectral signal types (singlet and multiplet), as well as the suitability of the proposed substances for manual integration at different levels of challenge (e.g., interference as a result of the necessary suppression of a water signal or the coverage of different typical wine concentration ranges for a selection of major components, minor components, and additives). To show that this method can be universally applied, NMR measurement and the method of evaluation were not strictly elucidated. Fifteen international laboratories participated in the collaborative trial and determined six parameters in 10 samples. The values, in particular the reproducibility SD (SR), were compared with the expected Horwitz SD (SH) by forming the quotient SR/SH (i.e., the HorRat value). The resulting HorRat values of most parameters were predominantly between 0.6 and 1.5, and thus of an acceptable range.

  20. Quantitative NMR spectroscopy for gas analysis for production of primary reference gas mixtures.

    Science.gov (United States)

    Meyer, K; Rademann, K; Panne, U; Maiwald, M

    2017-02-01

    Due to its direct correlation to the number of spins within a sample quantitative NMR spectroscopy (qNMR) is a promising method with absolute comparison abilities in complex systems in technical, as well as metrological applications. Most of the samples studied with qNMR are in liquid state in diluted solutions, while gas-phase applications represent a rarely applied case. Commercially available NMR equipment was used for purity assessment of liquid and liquefied hydrocarbons serving as raw materials for production of primary reference gas standards. Additionally, gas-phase studies were performed within an online NMR flow probe, as well as in a high-pressure NMR setup to check feasibility as verification method for the composition of gas mixtures. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Hepatic lipid profiling of deer mice fed ethanol using {sup 1}H and {sup 31}P NMR spectroscopy: A dose-dependent subchronic study

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Harshica; Bhopale, Kamlesh K.; Boor, Paul J.; Ansari, G.A. Shakeel; Kaphalia, Bhupendra S., E-mail: bkaphali@utmb.edu

    2012-11-01

    Chronic alcohol abuse is a 2nd major cause of liver disease resulting in significant morbidity and mortality. Alcoholic liver disease (ALD) is characterized by a wide spectrum of pathologies starting from fat accumulation (steatosis) in early reversible stage to inflammation with or without fibrosis and cirrhosis in later irreversible stages. Previously, we reported significant steatosis in the livers of hepatic alcohol dehydrogenase (ADH)-deficient (ADH{sup −}) vs. hepatic ADH-normal (ADH{sup +}) deer mice fed 4% ethanol daily for 2 months [Bhopale et al., 2006, Alcohol 39, 179–188]. However, ADH{sup −} deer mice fed 4% ethanol also showed a significant mortality. Therefore, a dose-dependent study was conducted to understand the mechanism and identify lipid(s) involved in the development of ethanol-induced fatty liver. ADH{sup −} and ADH{sup +} deer mice fed 1, 2 or 3.5% ethanol daily for 2 months and fatty infiltration in the livers were evaluated by histology and by measuring dry weights of extracted lipids. Lipid metabolomic changes in extracted lipids were determined by proton ({sup 1}H) and {sup 31}phosphorus ({sup 31}P) nuclear magnetic resonance (NMR) spectroscopy. The NMR data was analyzed by hierarchical clustering (HC) and principle component analysis (PCA) for pattern recognition. Extensive vacuolization by histology and significantly increased dry weights of total lipids found only in the livers of ADH{sup −} deer mice fed 3.5% ethanol vs. pair-fed controls suggest a dose-dependent formation of fatty liver in ADH{sup −} deer mouse model. Analysis of NMR data of ADH{sup −} deer mice fed 3.5% ethanol vs. pair-fed controls shows increases for total cholesterol, esterified cholesterol, fatty acid methyl esters (FAMEs), triacylglycerides and unsaturation, and decreases for free cholesterol, phospholipids and allylic and diallylic protons. Certain classes of neutral lipids (cholesterol esters, fatty acyl chain (-COCH{sub 2}-) and FAMEs) were

  2. NMR spectroscopy and computing beyond myth and fiction

    CERN Document Server

    De Filippo, S

    1999-01-01

    Starting from the physical algebra, namely the algebra of operators corresponding to macroscopic measurements, a thorough classical theory of NMR spectroscopy is constructed. Its effectiveness in emulating quantum computing stems from the exponential growth of the classical phase space dimension with the number of magnetic nuclei per molecule, this solving a standing scientific dispute. As a by-product, the differential equations for the evolution of macroscopic variables give an exact setting for simulation of NMR spectroscopy both in general and for quantum computing emulation.

  3. Acid-base equilibrium in aqueous solutions of 1,3-dimethylbarbituric acid as studied by 13C NMR spectroscopy

    Science.gov (United States)

    Gryff-Keller, A.; Kraska-Dziadecka, A.

    2011-12-01

    13C NMR spectra of 1,3-dimethylbarbituric acid in aqueous solutions of various acidities and for various solute concentrations have been recorded and interpreted. The spectra recorded at pH = 2 and below contain the signals of the neutral solute molecule exclusively, while the ones recorded at pH = 7 and above only the signals of the appropriate anion, which has been confirmed by theoretical GIAO-DFT calculations. The signals in the spectra recorded for solutions of pH acid-base equilibrium. The kinetic data determined this way have been used to clarify the mechanisms of these processes. The numerical analysis has shown that under the investigated conditions deprotonation of the neutral solute molecules undergoes not only via a simple transfer of the C-H proton to water molecules but also through a process with participation of the barbiturate anions. Moreover, the importance of tautomerism, or association, or both these phenomena for the kinetics of the acid-base transformations in the investigated system has been shown. Qualitatively similar changes of 13C NMR spectra with the solution pH variation have been observed for the parent barbituric acid.

  4. NMR spectroscopy and chemical studies of an arabinan-rich system from the endosperm of the seed of Gleditsia triacanthos.

    Science.gov (United States)

    Navarro, Diego A; Cerezo, Alberto S; Stortz, Carlos A

    2002-02-11

    Exhaustive extraction of the endosperm from the seed of Gleditsia triacanthos using water at room temperature and 50 degrees C left a residue, which was further extracted at 95 degrees C. Precipitation of this extract with 2-propanol yielded major amounts of galactomannan components, while the supernatant was mainly composed of arabinose-rich constituents. Two fractions were obtained by anion-exchange chromatography. The fraction that eluted with water is an arabinan with (1-->5) alpha-L linkages and branching mainly on C-2, accompanied with equal amounts of a low-galactose galactomannan oligosaccharide, and a small proportion of a beta-(1-->4)-galactan. The fraction eluted with an increased ionic strength consists mainly of a similar arabinan, and lower proportions of a high-galactose galactomannan, galactan, and protein. The arabinan moiety in both fractions was characterized by chemical analysis and 1D and 2D NMR spectroscopic techniques.

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

    African Journals Online (AJOL)

    Preferred Customer

    3 Department of Physics, Arts and Science Faculty, Dumlupınar University, Kütahya, Turkey. 4 Department ... been studied experimentally and theoretically using nuclear magnetic resonance (NMR) spectroscopy. 1H, 13C, ... INTRODUCTION.

  6. NMR Structural Studies on Alamethicin Dimers

    Institute of Scientific and Technical Information of China (English)

    李星

    2003-01-01

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

  7. 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...

  8. Using NMR Spectroscopy to Investigate the Solution Behavior of Nerve Agents and Their Binding to Acetylcholinesterase

    Science.gov (United States)

    2016-01-01

    USING NMR SPECTROSCOPY TO INVESTIGATE THE SOLUTION BEHAVIOR OF NERVE AGENTS AND THEIR BINDING TO...XX-01-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) Jan – Jun 2015 4. TITLE AND SUBTITLE Using NMR Spectroscopy to Investigate the...MOLECULAR MOTIONS AND NMR SPECTROSCOPY ...................................................................................................3 4. THE

  9. Forensic examination of electrical tapes using high resolution magic angle spinning ¹H NMR spectroscopy.

    Science.gov (United States)

    Schoenberger, Torsten; Simmross, Ulrich; Poppe, Christian

    2016-01-01

    The application of high resolution magic angle spinning (HR-MAS) (1)H NMR spectroscopy is ideally suited for the differentiation of plastics. In addition to the actual material composition, the different types of polymer architectures and tacticity provide characteristic signals in the fingerprint of the (1)H NMR spectra. The method facilitates forensic comparison, as even small amounts of insoluble but swellable plastic particles are utilized. The performance of HR-MAS NMR can be verified against other methods that were recently addressed in various articles about forensic tape comparison. In this study samples of the 90 electrical tapes already referenced by the FBI laboratory were used. The discrimination power of HR-MAS is demonstrated by the fact that more tape groups can be distinguished by NMR spectroscopy than by using the combined evaluation of several commonly used analytical techniques. An additional advantage of this robust and quick method is the very simple sample preparation.

  10. Oxidative stress-induced metabolic changes in mouse C2C12 myotubes studied with high-resolution 13C, 1H, and 31P NMR spectroscopy.

    Science.gov (United States)

    Straadt, Ida K; Young, Jette F; Petersen, Bent O; Duus, Jens Ø; Gregersen, Niels; Bross, Peter; Oksbjerg, Niels; Theil, Peter K; Bertram, Hanne C

    2010-02-10

    In this study, stress in relation to slaughter was investigated in a model system by the use of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy for elucidating changes in the metabolites in C2C12 myotubes exposed to H(2)O(2)-induced stress. Oxidative stress resulted in lower levels of several metabolites, mainly amino acids; however, higher levels of alanine were apparent in the (13)C spectra after incubation with [(13)C(1)]glucose. In the (13)C spectra [(13)C(3)]lactate tended to increase after exposure to increasing concentrations of H(2)O(2); conversely, a tendency to lower levels of the unlabeled ((12)C) lactate were identified in the (1)H spectra after stress exposure. These data indicate an increase in de novo synthesis of alanine, concomitant with a release of lactate from the myotubes to the medium at oxidative stress conditions. The changes in the metabolite levels could possibly be useful as markers for meat quality traits.

  11. The Effect of Season on the Metabolic Profile of the European Clam Ruditapes decussatus as Studied by 1H-NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Violetta Aru

    2017-07-01

    Full Text Available In this study, the metabolome of Ruditapes decussatus, an economically and ecologically important marine bivalve species widely distributed in the Mediterranean region, was characterized by using proton Nuclear Magnetic Resonance (1H-NMR spectroscopy. Significant seasonal variations in the content of carbohydrates and free amino acids were observed. The relative amounts of alanine and glycine were found to exhibit the same seasonal pattern as the temperature and salinity at the harvesting site. Several putative sex-specific biomarkers were also discovered. Substantial differences were found for alanine and glycine, whose relative amounts were higher in males, while acetoacetate, choline and phosphocholine were more abundant in female clams. These findings reveal novel insights into the baseline metabolism of the European clam and represent a step forward towards a comprehensive metabolic characterization of the species. Besides providing a holistic view on the prominent nutritional components, the characterization of the metabolome of this bivalve represents an important prerequisite for elucidating the underlying metabolic pathways behind the environment-organism interactions.

  12. Functional Groups Determine Biochar Properties (pH and EC) as Studied by Two-Dimensional (13)C NMR Correlation Spectroscopy.

    Science.gov (United States)

    Li, Xiaoming; Shen, Qirong; Zhang, Dongqing; Mei, Xinlan; Ran, Wei; Xu, Yangchun; Yu, Guanghui

    2013-01-01

    While the properties of biochar are closely related to its functional groups, it is unclear under what conditions biochar develops its properties. In this study, two-dimensional (2D) (13)C nuclear magnetic resonance (NMR) correlation spectroscopy was for the first time applied to investigate the development of functional groups and establish their relationship with biochar properties. The results showed that the agricultural biomass carbonized to biochars was a dehydroxylation/dehydrogenation and aromatization process, mainly involving the cleavage of O-alkylated carbons and anomeric O-C-O carbons in addition to the production of fused-ring aromatic structures and aromatic C-O groups. With increasing charring temperature, the mass cleavage of O-alkylated groups and anomeric O-C-O carbons occurred prior to the production of fused-ring aromatic structures. The regression analysis between functional groups and biochar properties (pH and electrical conductivity) further demonstrated that the pH and electrical conductivity of rice straw derived biochars were mainly determined by fused-ring aromatic structures and anomeric O-C-O carbons, but the pH of rice bran derived biochars was determined by both fused-ring aromatic structures and aliphatic O-alkylated (HCOH) carbons. In summary, this work suggests a novel tool for characterising the development of functional groups in biochars.

  13. Functional Groups Determine Biochar Properties (pH and EC as Studied by Two-Dimensional (13C NMR Correlation Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Xiaoming Li

    Full Text Available While the properties of biochar are closely related to its functional groups, it is unclear under what conditions biochar develops its properties. In this study, two-dimensional (2D (13C nuclear magnetic resonance (NMR correlation spectroscopy was for the first time applied to investigate the development of functional groups and establish their relationship with biochar properties. The results showed that the agricultural biomass carbonized to biochars was a dehydroxylation/dehydrogenation and aromatization process, mainly involving the cleavage of O-alkylated carbons and anomeric O-C-O carbons in addition to the production of fused-ring aromatic structures and aromatic C-O groups. With increasing charring temperature, the mass cleavage of O-alkylated groups and anomeric O-C-O carbons occurred prior to the production of fused-ring aromatic structures. The regression analysis between functional groups and biochar properties (pH and electrical conductivity further demonstrated that the pH and electrical conductivity of rice straw derived biochars were mainly determined by fused-ring aromatic structures and anomeric O-C-O carbons, but the pH of rice bran derived biochars was determined by both fused-ring aromatic structures and aliphatic O-alkylated (HCOH carbons. In summary, this work suggests a novel tool for characterising the development of functional groups in biochars.

  14. Insights into the metabolic response to traumatic brain injury as revealed by 13C NMR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Brenda eBartnik-Olson

    2013-10-01

    Full Text Available The present review highlights critical issues related to cerebral metabolism following traumatic brain injury (TBI and the use of 13C labeled substrates and nuclear magnetic resonance (NMR spectroscopy to study these changes. First we address some pathophysiologic factors contributing to metabolic dysfunction following TBI. We then examine how 13C NMR spectroscopy strategies have been used to investigate energy metabolism, neurotransmission, the intracellular redox state, and neuroglial compartmentation following injury. 13C NMR spectroscopy studies of brain extracts from animal models of TBI have revealed enhanced glycolytic production of lactate, evidence of pentose phosphate pathway (PPP activation, and alterations in neuronal and astrocyte oxidative metabolism that are dependent on injury severity. Differential incorporation of label into glutamate and glutamine from 13C labeled glucose or acetate also suggest TBI-induced adaptations to the glutamate-glutamine cycle.

  15. Advanced solid-state NMR spectroscopy of natural organic matter.

    Science.gov (United States)

    Mao, Jingdong; Cao, Xiaoyan; Olk, Dan C; Chu, Wenying; Schmidt-Rohr, Klaus

    2017-05-01

    Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially a systematic approach to NOM characterization, and their applications to the study of NOM. We discuss some basics of how to acquire high-quality and quantitative solid-state (13)C NMR spectra, and address some common technical mistakes that lead to unreliable spectra of NOM. The identification of specific functional groups in NOM, primarily based on (13)C spectral-editing techniques, is described and the theoretical background of some recently-developed spectral-editing techniques is provided. Applications of solid-state NMR to investigating nitrogen (N) in NOM are described, focusing on limitations of the widely used (15)N CP/MAS experiment and the potential of improved advanced NMR techniques for characterizing N forms in NOM. Then techniques used for identifying proximities, heterogeneities and domains are reviewed, and some examples provided. In addition, NMR techniques for studying segmental dynamics in NOM are reviewed. We also briefly discuss applications of solid-state NMR to NOM from various sources, including soil organic matter, aquatic organic matter, organic matter in atmospheric particulate matter, carbonaceous meteoritic organic matter, and fossil fuels. Finally, examples of NMR-based structural models and an outlook are provided. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. NMR contributions to structural dynamics studies of intrinsically disordered proteins☆

    Science.gov (United States)

    Konrat, Robert

    2014-01-01

    Intrinsically disordered proteins (IDPs) are characterized by substantial conformational plasticity. Given their inherent structural flexibility X-ray crystallography is not applicable to study these proteins. In contrast, NMR spectroscopy offers unique opportunities for structural and dynamic studies of IDPs. The past two decades have witnessed significant development of NMR spectroscopy that couples advances in spin physics and chemistry with a broad range of applications. This article will summarize key advances in basic physical-chemistry and NMR methodology, outline their limitations and envision future R&D directions. PMID:24656082

  17. Solid-State NMR Spectroscopy of Metal–Organic Framework Compounds (MOFs

    Directory of Open Access Journals (Sweden)

    Stefan Kaskel

    2012-11-01

    Full Text Available Nuclear Magnetic Resonance (NMR spectroscopy is a well-established method for the investigation of various types of porous materials. During the past decade, metal–organic frameworks have attracted increasing research interest. Solid-state NMR spectroscopy has rapidly evolved into an important tool for the study of the structure, dynamics and flexibility of these materials, as well as for the characterization of host–guest interactions with adsorbed species such as xenon, carbon dioxide, water, and many others. The present review introduces and highlights recent developments in this rapidly growing field.

  18. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  19. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  20. Ion counting in supercapacitor electrodes using NMR spectroscopy.

    Science.gov (United States)

    Griffin, John M; Forse, Alexander C; Wang, Hao; Trease, Nicole M; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P

    2014-01-01

    (19)F NMR spectroscopy has been used to study the local environments of anions in supercapacitor electrodes and to quantify changes in the populations of adsorbed species during charging. In the absence of an applied potential, anionic species adsorbed within carbon micropores (in-pore) are distinguished from those in large mesopores and spaces between particles (ex-pore) by a characteristic nucleus-independent chemical shift (NICS). Adsorption experiments and two-dimensional exchange experiments confirm that anions are in dynamic equilibrium between the in- and ex-pore environments with an exchange rate in the order of tens of Hz. (19)F in situ NMR spectra recorded at different charge states reveal changes in the intensity and NICS of the in-pore resonances, which are interpreted in term of changes in the population and local environments of the adsorbed anions that arise due to the charge-storage process. A comparison of the results obtained for a range of electrolytes reveals that several factors influence the charging mechanism. For a tetraethylammonium tetrafluoroborate electrolyte, positive polarisation of the electrode is found to proceed by anion adsorption at a low concentration, whereas increased ion exchange plays a more important role for a high concentration electrolyte. In contrast, negative polarization of the electrode proceeds by cation adsorption for both concentrations. For a tetrabutylammonium tetrafluoroborate electrolyte, anion expulsion is observed in the negative charging regime; this is attributed to the reduced mobility and/or access of the larger cations inside the pores, which forces the expulsion of anions in order to build up ionic charge. Significant anion expulsion is also observed in the negative charging regime for alkali metal bis(trifluoromethane)sulfonimide electrolytes, suggesting that more subtle factors also affect the charging mechanism.

  1. NMR methodologies for studying mitochondrial bioenergetics.

    Science.gov (United States)

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

    2012-01-01

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

  2. Investigation of Rhodopsin Dynamics in its Signaling State by Solid-State Deuterium NMR Spectroscopy

    Science.gov (United States)

    Struts, Andrey V.; Chawla, Udeep; Perera, Suchithranga M.D.C.; Brown, Michael F.

    2017-01-01

    Site-directed deuterium NMR spectroscopy is a valuable tool to study the structural dynamics of biomolecules in cases where solution NMR is inapplicable. Solid-state 2H NMR spectral studies of aligned membrane samples of rhodopsin with selectively labeled retinal provide information on structural changes of the chromophore in different protein states. In addition, solid-state 2H NMR relaxation time measurements allow one to study the dynamics of the ligand during the transition from the inactive to the active state. Here we describe the methodological aspects of solid-state 2H NMR spectroscopy for functional studies of rhodopsin, with an emphasis on the dynamics of the retinal cofactor. We provide complete protocols for the preparation of NMR samples of rhodopsin with 11-cis-retinal selectively deuterated at the methyl groups in aligned membranes. In addition, we review optimized conditions for trapping the rhodopsin photointermediates; and lastly we address the challenging problem of trapping the signaling state of rhodopsin in aligned membrane films. PMID:25697522

  3. Chemical-shift-resolved ¹⁹F NMR spectroscopy between 13.5 and 135 MHz: Overhauser-DNP-enhanced diagonal suppressed correlation spectroscopy.

    Science.gov (United States)

    George, Christy; Chandrakumar, Narayanan

    2014-08-01

    Overhauser-DNP-enhanced homonuclear 2D (19)F correlation spectroscopy with diagonal suppression is presented for small molecules in the solution state at moderate fields. Multi-frequency, multi-radical studies demonstrate that these relatively low-field experiments may be operated with sensitivity rivalling that of standard 200-1000 MHz NMR spectroscopy. Structural information is accessible without a sensitivity penalty, and diagonal suppressed 2D NMR correlations emerge despite the general lack of multiplet resolution in the 1D ODNP spectra. This powerful general approach avoids the rather stiff excitation, detection, and other special requirements of high-field (19)F NMR spectroscopy.

  4. Simultaneous 31P-NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: a correlation study

    DEFF Research Database (Denmark)

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

    1995-01-01

    A large number of studies have shown amplitude and spectral changes of the electromyogram during exercise, leading to several theories of how these changes might be related to the underlying metabolic changes. The amplitude and spectral changes are generally interpreted as changes in motor unit...... recruitment and a reduction of the muscle fiber conduction velocity due to proton or lactate accumulation. This study focuses on the causality of spectral changes of the surface electromyogram and proton or lactate accumulation and how the changes in motor unit recruitment are related to the metabolic status...... recruitment (as judged by the root mean square of the surface electromyogram) increased hyperbolically during the submaximal static exercise, with decreasing phosphocreatine-to-P(i) ratio reaching maximum at 0.6 (exhaustion), and seems to constitute a consistent metabolic limit to the exercise. The increased...

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  6. Multidimensional solid-state NMR spectroscopy of plant cell walls.

    Science.gov (United States)

    Wang, Tuo; Phyo, Pyae; Hong, Mei

    2016-09-01

    Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant cell walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant cell walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of cellulose and matrix polysaccharides in plant cell walls. These studies have focused on primary cell walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) cellulose, hemicellulose, and pectins form a single network in the primary cell wall; 2) in dicot cell walls, the protein expansin targets the hemicellulose-enriched region of the cellulose microfibril for its wall-loosening function; and 3) primary wall cellulose has polymorphic structures that are distinct from the microbial cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant cell wall structure and function.

  7. Structural investigation of bistrifluron using x-ray crystallography, NMR spectroscopy, and molecular modeling

    CERN Document Server

    Moon, J K; Rhee, S K; Kim, G B; Yun, H S; Chung, B J; Lee, S S; Lim, Y H

    2002-01-01

    A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

  8. Slow-spinning low-sideband HR-MAS NMR spectroscopy: delicate analysis of biological samples

    Science.gov (United States)

    Renault, Marie; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano

    2013-11-01

    High-Resolution Magic-Angle Spinning (HR-MAS) NMR spectroscopy has become an extremely versatile analytical tool to study heterogeneous systems endowed with liquid-like dynamics. Spinning frequencies of several kHz are however required to obtain NMR spectra, devoid of spinning sidebands, with a resolution approaching that of purely isotropic liquid samples. An important limitation of the method is the large centrifugal forces that can damage the structure of the sample. In this communication, we show that optimizing the sample preparation, particularly avoiding air bubbles, and the geometry of the sample chamber of the HR-MAS rotor leads to high-quality low-sideband NMR spectra even at very moderate spinning frequencies, thus allowing the use of well-established solution-state NMR procedures for the characterization of small and highly dynamic molecules in the most fragile samples, such as live cells and intact tissues.

  9. Slow-spinning low-sideband HR-MAS NMR spectroscopy: delicate analysis of biological samples

    Science.gov (United States)

    Renault, Marie; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano

    2013-01-01

    High-Resolution Magic-Angle Spinning (HR-MAS) NMR spectroscopy has become an extremely versatile analytical tool to study heterogeneous systems endowed with liquid-like dynamics. Spinning frequencies of several kHz are however required to obtain NMR spectra, devoid of spinning sidebands, with a resolution approaching that of purely isotropic liquid samples. An important limitation of the method is the large centrifugal forces that can damage the structure of the sample. In this communication, we show that optimizing the sample preparation, particularly avoiding air bubbles, and the geometry of the sample chamber of the HR-MAS rotor leads to high-quality low-sideband NMR spectra even at very moderate spinning frequencies, thus allowing the use of well-established solution-state NMR procedures for the characterization of small and highly dynamic molecules in the most fragile samples, such as live cells and intact tissues. PMID:24284435

  10. Clathrate Structure Determination by Combining Crystal Structure Prediction with Computational and Experimental (129) Xe NMR Spectroscopy.

    Science.gov (United States)

    Selent, Marcin; Nyman, Jonas; Roukala, Juho; Ilczyszyn, Marek; Oilunkaniemi, Raija; Bygrave, Peter J; Laitinen, Risto; Jokisaari, Jukka; Day, Graeme M; Lantto, Perttu

    2017-01-23

    An approach is presented for the structure determination of clathrates using NMR spectroscopy of enclathrated xenon to select from a set of predicted crystal structures. Crystal structure prediction methods have been used to generate an ensemble of putative structures of o- and m-fluorophenol, whose previously unknown clathrate structures have been studied by (129) Xe NMR spectroscopy. The high sensitivity of the (129) Xe chemical shift tensor to the chemical environment and shape of the crystalline cavity makes it ideal as a probe for porous materials. The experimental powder NMR spectra can be used to directly confirm or reject hypothetical crystal structures generated by computational prediction, whose chemical shift tensors have been simulated using density functional theory. For each fluorophenol isomer one predicted crystal structure was found, whose measured and computed chemical shift tensors agree within experimental and computational error margins and these are thus proposed as the true fluorophenol xenon clathrate structures.

  11. NMR Dynamic Studies in Living Systems

    Institute of Scientific and Technical Information of China (English)

    闫永彬; 范明杰; 罗雪春; 张日清

    2002-01-01

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

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

    Science.gov (United States)

    2017-01-01

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

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

    Science.gov (United States)

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

    2004-02-01

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

  14. Simultaneous 19F-1H medium resolution NMR spectroscopy for online reaction monitoring

    Science.gov (United States)

    Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael

    2014-12-01

    Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16″ fluorinated ethylene propylene (FEP) tube with an ID of 0.04″ (1.02 mm) was used as a flow cell in combination with a 5 mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32 MHz and 40.68 MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500 MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16″ FEP tube set-up with an ID of 1.02 mm was characterised regarding the limit of detection (LOQ (1H) = 0.335 mol L-1 and LOQ (19F) = 0.130 mol L-1 for trifluoroethanol in

  15. Online T5 learning model to enhance chemistry students’ understanding of NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    Saksri Supasorn

    2014-08-01

    Full Text Available Regular lecture-based teaching approaches sometimes fail to enhance students’ understanding of some practice-based chemistry topics such as Nuclear Magnetic Resonance (NMR spectroscopy. A new task-based approach called the T5 learning model was introduced for 48 students studying NMR in the Spectroscopic Methods for Chemical Identification course in 2011. Four different NMR learning environments based on T5 learning models were developed. The students were requested to participate in the following online processes in each environment: 1 complete an individual task, 2 provide feedback and evaluate three anonymous peer tasks, 3 adjust their individual task and evaluate peer feedback, 4 complete a team task and evaluate the effort of each group member, and 5 get feedback from instructor to fulfill understanding. The result showed that the students obtained post-achievement NMR score (mean 24.25, SD 4.80 statistically significantly higher than pre- achievement score (mean 12.29, SD 1.69 at p-value of 0.05. In addition, the implementation of T5-D4LP NMR course in each year during 2010-2012 showed that the students achieved high score (about 70% in the NMR topics. The student evaluation of the T5 NMR learning environments revealed that they agreed that peer feedback with instructor facilitation engaged them in deep learning and effectively promoted their conceptual understanding.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-20

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Richards, T.

    1984-09-01

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

  18. Study by Use of (1)H NMR Spectroscopy of the Adsorption and Decomposition of Glycine, Leucine, and Derivatives in TiO2 Photocatalysis.

    Science.gov (United States)

    Nosaka, Atsuko Y; Tanaka, Goro; Nosaka, Yoshio

    2014-06-26

    The photocatalytic decomposition and adsorption of glycine (Gly), Gly-Gly, and Gly-Gly-Gly, and leucine (Leu), Leu-Gly, Gly-Leu, and Leu-Gly-Gly, in TiO2 (100% anatase crystal form) aqueous suspension were investigated by (1)H NMR spectroscopy. The side chain of Leu, the carboxylic group, and the peptide bond were recognized as the adsorptive sites of the peptides on the surface of TiO2. For Gly-Leu and Leu-Gly-Gly, the photocatalytic decomposition that took place under UV irradiation resulted from the preferable adsorption of the hydrophobic side chain of Leu on the TiO2 surface, while for Gly-Gly and Gly-Gly-Gly, the photodecomposition proceeded by weak adsorption of the peptide bonds on the surface of TiO2.

  19. Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China

    Science.gov (United States)

    Aquatic plants are involved in the storage and release capacity for organic matter and nutrients. In this study, solid 13C and solution 31P nuclear magnetic resonance (NMR) spectroscopy were used to characterize the biomass samples of six aquatic plants. Solid 13C NMR spectroscopy revealed the domin...

  20. Synthesis and proton NMR spectroscopy of intra-vesicular gamma-aminobutyric acid (GABA).

    Science.gov (United States)

    Wang, Luke Y-J; Tong, Rong; Kohane, Daniel S

    2013-01-01

    We report the synthesis of vesicles containing gamma-aminobutyric acid (GABA), and their proton nuclear magnetic resonance ((1)H NMR) spectra. These vesicles were constructed to more closely mimic the intracellular environment wherein GABA exists. For this study, these GABA-containing vesicles were examined under (1)H NMR as a potential platform for future studies on the differences between aqueous phantoms, ex vivo brain extracts, and in vivo magnetic resonance spectroscopy results. We found that intra-vesicular GABA faithfully yielded the chemical shifts and J-coupling constants of free aqueous GABA, alongside the chemical shift signals of the vesicle wall.

  1. Use of the Fourier series window protocol with a zig-zag surface coil in 31P NMR human skin spectroscopy. A theoretical study.

    Science.gov (United States)

    Bastin, M E; Cowie, A G; Manners, D N; Hands, L J; Styles, P

    1996-08-01

    The use of a zig-zag surface coil with a three-pulse Fourier Series Window (FSW) has been suggested as a means by which in vivo NMR spectroscopic studies of human skin can be performed. Using direct numerical simulations of the magnetic field profile of a 10 limb zig-zag surface coil, the role of the FSW in reducing NMR signals originating from the deeper skeletal muscle layers is examined theoretically. The extent of muscle signal contamination is determined for different coil inter-limb spacings and pulse width settings. The optimum inter-limb spacing for studying living human skin, that which minimizes signal contamination and maximizes skin signal collected, is shown to be between 4 and 6 mm. These calculations demonstrate that the FSW and zig-zag surface coil offer a protocol for investigating the metabolism of large areas of surface tissue while keeping signal contamination from the deeper skeletal muscle layers down to an acceptable level.

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

    Science.gov (United States)

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

    2014-10-01

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

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Science.gov (United States)

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

    1993-01-01

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

  5. Potential of NMR Spectroscopy in the Characterization of Nonconventional Oils

    Directory of Open Access Journals (Sweden)

    Abdul Majid

    2014-01-01

    Full Text Available NMR spectroscopy was applied for the characterization of two biomass based pyrolysis oil samples. The samples were extracted in various solvents and the extracts were investigated by both 1H and 13C NMR spectroscopy. Subsequent evaluation of the integrated analytical data revealed chemical information regarding semiquantitative estimation of various functional groups. This information could not have been obtained readily from the individual spectroscopic techniques. Semiquantitative estimation of the various functional groups allowed a comparison of the extraction efficiency of these groups in various solvents. The method is based on the premise that although the number of individual molecular species in pyrolysis oil liquid is large, most of these species are composed of a limited number of functional groups. The methodology provided information on the concentration of chemical functionalities that are potentially useful for synthetic modifications and may help to guide the use of pyrolysis oil as a chemical feedstock. The approach described is expected to be generally applicable to complex mixture of hydrocarbon oils such as bio-oils, oil sands bitumen, and coal pyrolysis oils.

  6. Investigating albendazole desmotropes by solid-state NMR spectroscopy.

    Science.gov (United States)

    Chattah, Ana K; Zhang, Rongchun; Mroue, Kamal H; Pfund, Laura Y; Longhi, Marcela R; Ramamoorthy, Ayyalusamy; Garnero, Claudia

    2015-03-02

    Characterization of the molecular structure and physicochemical solid-state properties of the solid forms of pharmaceutical compounds is a key requirement for successful commercialization as potential active ingredients in drug products. These properties can ultimately have a critical effect on the solubility and bioavailability of the final drug product. Here, the desmotropy of Albendazole forms I and II was investigated at the atomic level. Ultrafast magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy, together with powder X-ray diffraction, thermal analysis, and Fourier transform infrared spectroscopy, were performed on polycrystalline samples of the two solids in order to fully characterize and distinguish the two forms. High-resolution one-dimensional (1)H, (13)C, and (15)N together with two-dimensional (1)H/(1)H single quantum-single quantum, (1)H/(1)H single quantum-double quantum, and (1)H/(13)C chemical shift correlation solid-state NMR experiments under MAS conditions were extensively used to decipher the intramolecular and intermolecular hydrogen bonding interactions present in both solid forms. These experiments enabled the unequivocal identification of the tautomers of each desmotrope. Our results also revealed that both solid forms may be described as dimeric structures, with different intermolecular hydrogen bonds connecting the tautomers in each dimer.

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

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, V V

    2005-04-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-02-01

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

  9. Complex Mixture Analysis of Organic Compounds in Yogurt by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yi Lu

    2016-06-01

    Full Text Available NMR measurements do not require separation and chemical modification of samples and therefore rapidly and directly provide non-targeted information on chemical components in complex mixtures. In this study, one-dimensional (1H, 13C, and 31P and two-dimensional (1H-13C and 1H-31P NMR spectroscopy were conducted to analyze yogurt without any pretreatment. 1H, 13C, and 31P NMR signals were assigned to 10 types of compounds. The signals of α/β-lactose and α/β-galactose were separately observed in the 1H NMR spectra. In addition, the signals from the acyl chains of milk fats were also successfully identified but overlapped with many other signals. Quantitative difference spectra were obtained by subtracting the diffusion ordered spectroscopy (DOSY spectra from the quantitative 1H NMR spectra. This method allowed us to eliminate interference on the overlaps; therefore, the correct intensities of signals overlapped with those from the acyl chains of milk fat could be determined directly without separation. Moreover, the 1H-31P HMBC spectra revealed for the first time that N-acetyl-d-glucosamine-1-phosphate is contained in yogurt.

  10. Proton-Based Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Zhang, Rongchun; Mroue, Kamal H; Ramamoorthy, Ayyalusamy

    2017-04-18

    Protons are vastly abundant in a wide range of exciting macromolecules and thus can be a powerful probe to investigate the structure and dynamics at atomic resolution using solid-state NMR (ssNMR) spectroscopy. Unfortunately, the high signal sensitivity, afforded by the high natural-abundance and high gyromagnetic ratio of protons, is greatly compromised by severe line broadening due to the very strong (1)H-(1)H dipolar couplings. As a result, protons are rarely used, in spite of the desperate need for enhancing the sensitivity of ssNMR to study a variety of systems that are not amenable for high resolution investigation using other techniques including X-ray crystallography, cryo-electron microscopy, and solution NMR spectroscopy. Thanks to the remarkable improvement in proton spectral resolution afforded by the significant advances in magic-angle-spinning (MAS) probe technology, (1)H ssNMR spectroscopy has recently attracted considerable attention in the structural and dynamics studies of various molecular systems. However, it still remains a challenge to obtain narrow (1)H spectral lines, especially from proteins, without resorting to deuteration. In this Account, we review recent proton-based ssNMR strategies that have been developed in our laboratory to further improve proton spectral resolution without resorting to chemical deuteration for the purposes of gaining atomistic-level insights into molecular structures of various crystalline solid systems, using small molecules and peptides as illustrative examples. The proton spectral resolution enhancement afforded by the ultrafast MAS frequencies up to 120 kHz is initially discussed, followed by a description of an ensemble of multidimensional NMR pulse sequences, all based on proton detection, that have been developed to obtain in-depth information from dipolar couplings and chemical shift anisotropy (CSA). Simple single channel multidimensional proton NMR experiments could be performed to probe the proximity

  11. Analyzing temperature-induced transitions in disordered proteins by NMR spectroscopy and secondary chemical shift analyses

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Poulsen, Flemming Martin; Kragelund, Birthe Brandt

    2012-01-01

    Intrinsically disordered proteins are abundant in nature and perform many important physiological functions. Multidimensional NMR spectroscopy has been crucial for the understanding of the conformational properties of disordered proteins and is increasingly used to probe their conformational...... ensembles. Compared to folded proteins, disordered proteins are more malleable and more easily perturbed by environmental factors. Accordingly, the experimental conditions and especially the temperature modify the structural and functional properties of disordered proteins. This chapter discusses practical...... aspects of NMR studies of temperature-induced structural changes in disordered proteins using chemical shifts....

  12. Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, D.J.

    1995-07-01

    NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.

  13. Nanostructures of Mg0.65Ti0.35Dx studied with x-ray diffraction, neutron diffraction, and magic-angle-spinning H2 NMR spectroscopy

    Science.gov (United States)

    Srinivasan, S.; Magusin, P. C. M. M.; Kalisvaart, W. P.; Notten, P. H. L.; Cuevas, F.; Latroche, M.; van Santen, R. A.

    2010-02-01

    Magnesium transition-metal alloys have a high hydrogen-storage capacity and show improved hydrogen-uptake and -release kinetics compared to magnesium alone. In the present study we have investigated the structure of bulk magnesium-titanium deuteride Mg0.65Ti0.35Dx prepared via mechanical alloying and gas-phase deuterium absorption by combined use of x-ray diffraction (XRD), neutron diffraction, and magic-angle-spinning H2 nuclear magnetic resonance (NMR). The initial ball-milled alloy has two XRD-distinct Mg and Ti fcc phases. Even after prolonged exposure to deuterium gas at 75 bar and 175°C the materials with and without palladium catalyst are only partly deuterated. Deuterium loading causes the formation of, on the one hand, bct (rutile) MgD2 nanodomains with interdispersed TiDy layers and, on the other hand, a separate fcc (fluorite) TiDz phase. The TiDy phase is XRD invisible, but shows clearly up at a H2 NMR shift of -43ppm between the shift of MgD2 (3 ppm) and the Knight shift of the TiDz phase (-143ppm) . Exchange NMR indicates complete deuterium exchange at 25°C between the MgD2 and TiDy phase within 1 s, as consistent with intimate contacts between these phases. Combined analysis of the XRD and NMR peak areas suggests that the deuterium concentrations y and z in the TiDy and TiDz domains are about 1.5 and 2.0, respectively. Comparing the intrinsic cell parameters of rutile MgH2 and fluorite TiH2 , we propose that stabilization of the mixed nanocomposite may arise from a coherent coupling between the crystal structures of the rutile MgD2 nanodomains and the thin layers of fcc TiDy .

  14. Engagement of CF3 group in N-H···F-C hydrogen bond in the solution state: NMR spectroscopy and MD simulation studies.

    Science.gov (United States)

    Chaudhari, Sachin Rama; Mogurampelly, Santosh; Suryaprakash, N

    2013-01-31

    Unambiguous evidence for the engagement of CF(3) group in N-H···F-C hydrogen bond in a low polarity solvent, the first observation of its kind, is reported. The presence of such weak molecular interactions in the solution state is convincingly established by one and two-dimensional (1)H, (19)F, and natural abundant (15)N NMR spectroscopic studies. The strong and direct evidence is derived by the observation of through-space couplings, such as, (1h)J(FH), (1h)J(FN), and (2h)J(FF), where the spin polarization is transmitted through hydrogen bond. In an interesting example of a molecule containing two CF(3) groups getting simultaneously involved in hydrogen bond, where hydrogen bond mediated couplings are not reflected in the NMR spectrum, (19)F-(19)F NOESY experiment yielded confirmatory evidence. Significant deviations in the strengths of (1)J(NH), variable temperature, and the solvent induced perturbations yielded additional support. The NMR results are corroborated by both DFT calculations and MD simulations, where the quantitative information on different ways of involvement of fluorine in two and three centered hydrogen bonds, their percentage of occurrences, and geometries have been obtained. The hydrogen bond interaction energies have also been calculated.

  15. Ageing of Starch Based Systems as observed with FT-IR and Solid State NMR Spectroscopy

    NARCIS (Netherlands)

    Smits, A.L.M.; Ruhnau, F.C.; Vliegenthart, J.F.G.; Soest, van J.J.G.

    1998-01-01

    The retrogradation and physical ageing of model starch systems with respect to their glass transition temperatures Tg have been investigated by Fourier transform infrared spectroscopy and solid state NMR spectroscopy. Diffuse reflectance Fourier transform infrared (DRIFT) spectra demonstrate the com

  16. Ageing of starch based systems as observed with FT-IR and solid state NMR spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Smits, A.L.M.; Ruhnau, F.C.; Soest, J.J.G. van

    1998-01-01

    The retrogradation and physical ageing of model starch systems with respect to their glass transition temperatures Tg have been investigated by Fourier transform infrared Spectroscopy and solid state NMR spectroscopy. Diffuse reflectance Fourier transform infrared (DRIFT) spectra demonstrate the com

  17. Actinide(IV) and actinide(VI) carbonate speciation studies by PAS and NMR spectroscopies; Yucca Mountain Project: Milestone report 3031-WBS 1.2.3.4.1.3.1

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D.L.; Ekberg, S.A.; Morris, D.E.; Palmer, P.D.; Tait, C.D.

    1994-09-01

    Pulsed-laser photoacoustic spectroscopy (PAS) and Fourier-transform nuclear magnetic resonance (NMR) spectroscopy were used to study speciation of actinide(IV) and actinide(VI) ions (Np, Pu, Am) in aqueous carbonate solutions vs pH, carbonate content, actinide content, temperature. PAS focused on Pu(IV) speciation. Stability fields on a pH (8.4 to 12.0) versus total carbonate content (0.003 to 1.0 M) plot for dilute Pu(IV) carbonate species ([Pu]{sub tot} = 1 mM) were mapped. Four plutonium species, with absorption peaks at 486, 492, 500, and 512 nm were found. Loss of a single carbonate ligand does not account for the difference in speciation for the 486 and 492 nm absorption peaks, nor can any of the observed species be identified as colloidal Pu(IV). NMR data have been obtained for UO{sub 2}{sup 2+}, PuO{sub 2}{sup 2+} and AmO{sub 2}{sup 2+}. This report focuses on results for PuO{sub 2}{sup 2+}. The ligand exchange reaction between free and coordinated carbonate on the PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR spectroscopy. In each of the six different PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} samples, two NMR signals are present, one for the free carbonate ligand and one for the carbonate ligand coordinated to a paramagnetic plutonium metal center. The single{sup 13}C resonance line for coordinated carbonate is consistent with expectations of a monomeric PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} species in solution. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was used for determining ligand exchange parameters for paramagnetic actinide complexes. Eyring analysis at standard conditions provided activation parameters of {Delta}H = 38 KJ/M and {Delta}S = {minus}60 J/K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl(VI) carbonate complex self-exchange reaction.

  18. Fast acquisition of high-resolution 2D NMR spectroscopy in inhomogeneous magnetic fields

    Science.gov (United States)

    Lin, Liangjie; Wei, Zhiliang; Zeng, Qing; Yang, Jian; Lin, Yanqin; Chen, Zhong

    2016-05-01

    High-resolution nuclear magnetic resonance (NMR) spectroscopy plays an important role in chemical and biological analyses. In this study, we combine the J-coupling coherence transfer module with the echo-train acquisition technique for fast acquisition of high-resolution 2D NMR spectra in magnetic fields with unknown spatial variations. The proposed method shows satisfactory performance on a 5 mM ethyl 3-bromopropionate sample, under a 5-kHz (10 ppm at 11.7 T) B0 inhomogeneous field, as well as under varying degrees of pulse-flip-angle deviations. Moreover, a simulative ex situ NMR measurement is also conducted to show the effectiveness of the proposed pulse sequence.

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

    Science.gov (United States)

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

    2005-02-01

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

  20. Multiplicative or t1 Noise in NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Granwehr, Josef

    2005-01-25

    The signal in an NMR experiment is highly sensitive to fluctuations of the environment of the sample. If, for example, the static magnetic field B{sub 0}, the amplitude and phase of radio frequency (rf) pulses, or the resonant frequency of the detection circuit are not perfectly stable and reproducible, the magnetic moment of the spins is altered and becomes a noisy quantity itself. This kind of noise not only depends on the presence of a signal, it is in fact proportional to it. Since all the spins at a particular location in a sample experience the same environment at any given time, this noise primarily affects the reproducibility of an experiment, which is mainly of importance in the indirect dimensions of a multidimensional experiment, when intense lines are suppressed with a phase cycle, or for difference spectroscopy techniques. Equivalently, experiments which are known to be problematic with regard to their reproducibility, like flow experiments or experiments with a mobile target, tend to be affected stronger by multiplicative noise. In this article it is demonstrated how multiplicative noise can be identified and characterized using very simple, repetitive experiments. An error estimation approach is developed to give an intuitive, yet quantitative understanding of its properties. The consequences for multidimensional NMR experiments are outlined, implications for data analysis are shown, and strategies for the optimization of experiments are summarized.

  1. Metabolomic insight into soy sauce through (1)H NMR spectroscopy.

    Science.gov (United States)

    Ko, Bong-Kuk; Ahn, Hyuk-Jin; van den Berg, Frans; Lee, Cherl-Ho; Hong, Young-Shick

    2009-08-12

    Soy sauce, a well-known seasoning in Asia and throughout the world, consists of many metabolites that are produced during fermentation or aging and that have various health benefits. However, their comprehensive assessment has been limited due to targeted or instrumentally specific analysis. This paper presents for the first time a metabolic characterization of soy sauce, especially that aged up to 12 years, to obtain a global understanding of the metabolic variations through (1)H NMR spectroscopy coupled with multivariate pattern recognition techniques. Elevated amino acids and organic acids and the consumption of carbohydrate were associated with continuous involvement of microflora in aging for 12 years. In particular, continuous increases in the levels of betaine were found during aging for up to 12 years, demonstrating that microbial- or enzyme-related metabolites were also coupled with osmotolerant or halophilic bacteria present during aging. This work provides global insights into soy sauce through a (1)H NMR-based metabolomic approach that enhances the current understanding of the holistic metabolome and allows assessment of soy sauce quality.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Min Wang

    2017-03-01

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

  4. Feasibility study for the rapid screening of target molecules using translational diffusion coefficients: diffusion-ordered NMR spectroscopy of biological toxins.

    Science.gov (United States)

    Henderson, Terry J

    2010-02-01

    A panel of 15 biological toxins ranging between approximately 60-28,000 g/mol was used to evaluate the feasibility of screening aqueous samples for toxin analytes based on their translational diffusion coefficients, D(t). Toxin D(t) values were measured by pulsed-field gradient (1)H NMR spectroscopy using a bipolar pulse pair, longitudinal eddy current delay pulse sequence incorporating water suppression to achieve the maximum dynamic range for toxin signals. To collect data for an effective screening protocol, reference D(t) values were determined from five independent measurements at both 25 and 37 degrees C for all toxins in the panel. In the protocol, D(t) values are measured at both temperatures for a suspected toxin target in a sample, and for assignment as a potential toxin analyte, the measurements are required to fall within +/-0.25 x 10(-6) cm(2)/s of both reference D(t) values for at least one toxin in the panel. Only solution viscosity was found to influence sample D(t) measurements appreciably; however, the measurements are easily corrected for viscosity effects by calculating the D(t) value of the suspected toxin at infinite dilution. In conclusion, the protocol provides a rapid and effective means for screening aqueous samples for all toxins in the panel, narrowing toxin identification to < or = 2 possibilities in virtually all cases.

  5. Simulated biological effects of microgravity on phospholipid and energy metabolism of chicken embryonic brain cells studied by 31P-NMR spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Levels of phosphomonoester (PME), phosphodiester (PDE), ATP and pH in brain cells of chicken embryos rotated for 24 h in a clinostat during the period of hatching the 13th day (E13) and 15th day (E15) embryos were investigated by using 31P-NMR spectroscopy. Significant increases in the values of PME, ATP and pH were identified after E13 rotating for 24 h. With the same treatment, differences were obtained in the phospholipid and energy metabolism of E15, but no significant levels have been reached . The calorimetric assay (malachite green method) was used for measuring the activity of total ATPase. A dramatic decrease was evident in the activity of ATPase in brain cells of rotated E13 and E15. The former is more sensitive than the latter. All the levels mentioned above could restore in 24 h after the rotation stopped, except that the level of ATP was still higher than the control.

  6. Metabolic changes in rat prefrontal cortex and hippocampus induced by chronic morphine treatment studied ex vivo by high resolution 1H NMR spectroscopy.

    Science.gov (United States)

    Gao, Hongchang; Xiang, Yun; Sun, Ninglei; Zhu, Hang; Wang, Yaqiang; Liu, Maili; Ma, Yuanye; Lei, Hao

    2007-01-01

    Ex vivo(1)H NMR spectroscopy was used to measure changes in the concentrations of cerebral metabolites in the prefrontal cortex (PFC) and hippocampus of rats subjected to repeated morphine treatment known to cause tolerance/dependence. The results show that repeated morphine exposure induces significant changes in the concentrations of a number of cerebral metabolites, and such changes are region specific. After 10 days of repeated morphine treatment, the concentration of gamma-aminobutyric acid (GABA) increased significantly in the PFC (20+/-11%), but decreased in the hippocampus (-31+/-12%), compared to control. In contrast, the glutamate (Glu) concentrations in both the PFC (-15+/-8%) and hippocampus (-13+/-4%) decreased significantly. Significant changes were also observed in the concentrations of hippocampal glutamine (Gln), myo-inositol, taurine, and N-acetyl aspartate. These morphine-induced changes were reversed during a subsequent 5-day withdrawal period. It is suggested that the observed concentration changes for Glu, Gln and GABA are most likely the result of a shift in the steady-state equilibrium of the Gln-Glu-GABA metabolic cycle. Changes in the metabolism of this neurotransmitter system might be part of the adaptive measures taken by the central nervous system in response to repeated morphine exposure and subsequent withdrawal.

  7. A Study of the Solvation Structure of L-Leucine in Alcohol-Water Binary Solvents through Molecular Dynamics Simulations and FTIR and NMR Spectroscopy.

    Science.gov (United States)

    Takamuku, Toshiyuki; Hatomoto, Yohei; Tonegawa, Junko; Tsutsumi, Youichi; Umecky, Tatsuya

    2015-10-26

    The solvation structures of l-leucine (Leu) in aliphatic-alcohol-water and fluorinated-alcohol-water solvents are elucidated for various alcohol contents by using molecular dynamics (MD) simulations and IR, and (1) H and (13) C NMR spectroscopy. The aliphatic alcohols included methanol, ethanol, and 2-propanol, whereas the fluorinated alcohols were 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol. The MD results show that the hydrophobic alkyl moiety of Leu is surrounded by the alkyl or fluoroalkyl groups of the alcohol molecules. In particular, TFE and HFIP significantly solvate the alkyl group of Leu. IR spectra reveal that the Leu C-H stretching vibration blueshifts in fluorinated alcohol solutions with increasing alcohol content, whereas the vibration redshifts in aliphatic alcohol solutions. When the C-H stretching vibration blueshifts in the fluorinated alcohol solutions, the hydrogen and carbon atoms of the Leu alkyl group are magnetically shielded. Consequently, TFE and HFIP molecules may solvate the Leu alkyl group through the blue-shifting hydrogen bonds.

  8. Ferrous Iron Binding Key to Mms6 Magnetite Biomineralisation: A Mechanistic Study to Understand Magnetite Formation Using pH Titration and NMR Spectroscopy.

    Science.gov (United States)

    Rawlings, Andrea E; Bramble, Jonathan P; Hounslow, Andrea M; Williamson, Michael P; Monnington, Amy E; Cooke, David J; Staniland, Sarah S

    2016-06-01

    Formation of magnetite nanocrystals by magnetotactic bacteria is controlled by specific proteins which regulate the particles' nucleation and growth. One such protein is Mms6. This small, amphiphilic protein can self-assemble and bind ferric ions to aid in magnetite formation. To understand the role of Mms6 during in vitro iron oxide precipitation we have performed in situ pH titrations. We find Mms6 has little effect during ferric salt precipitation, but exerts greatest influence during the incorporation of ferrous ions and conversion of this salt to mixed-valence iron minerals, suggesting Mms6 has a hitherto unrecorded ferrous iron interacting property which promotes the formation of magnetite in ferrous-rich solutions. We show ferrous binding to the DEEVE motif within the C-terminal region of Mms6 by NMR spectroscopy, and model these binding events using molecular simulations. We conclude that Mms6 functions as a magnetite nucleating protein under conditions where ferrous ions predominate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. An Oil Spill in a Tube: An Accessible Approach for Teaching Environmental NMR Spectroscopy

    Science.gov (United States)

    Simpson, Andre´ J.; Mitchell, Perry J.; Masoom, Hussain; Mobarhan, Yalda Liaghati; Adamo, Antonio; Dicks, Andrew P.

    2015-01-01

    NMR spectroscopy has great potential as an instrumental method for environmental chemistry research and monitoring but may be underused in teaching laboratories because of its complexity and the level of expertise required in operating the instrument and interpreting data. This laboratory experiment introduces environmental NMR spectroscopy to…

  10. An Oil Spill in a Tube: An Accessible Approach for Teaching Environmental NMR Spectroscopy

    Science.gov (United States)

    Simpson, Andre´ J.; Mitchell, Perry J.; Masoom, Hussain; Mobarhan, Yalda Liaghati; Adamo, Antonio; Dicks, Andrew P.

    2015-01-01

    NMR spectroscopy has great potential as an instrumental method for environmental chemistry research and monitoring but may be underused in teaching laboratories because of its complexity and the level of expertise required in operating the instrument and interpreting data. This laboratory experiment introduces environmental NMR spectroscopy to…

  11. Determination of gluconeogenesis in man by the use of deuterium-NMR-spectroscopy

    CERN Document Server

    Rosian, E

    2000-01-01

    The aim of this dissertation is the quantification of the deuterium--distribution in human glucose by the use of the deuterium NMR spectroscopy of deuteriated water. The glucose production in human organism is composed of gluconeogenesis and glycolysis. The quantification of the part of gluconeogenesis on the total glucose production was determined by the use of deuterium NMR spectroscopy. (boteke)

  12. Applications of high-resolution solid-state NMR spectroscopy in food science.

    Science.gov (United States)

    Bertocchi, Fabio; Paci, Maurizio

    2008-10-22

    The principal applications of high-resolution solid-state NMR spectroscopy, in the field of food science, are reviewed, after a short general introduction, mainly focusing on the potential of these investigations, which are, today, routine tools for resolving technological problems. Selected examples of the applications in the field of food science of high-resolution solid-state NMR spectroscopy both in (13)C and in (1)H NMR particularly illustrative of the results obtainable are reported in some detail.

  13. {sup 7}Li NMR spectroscopy and ion conduction mechanism of composite gel polymer electrolyte: A comparative study with variation of salt and plasticizer with filler

    Energy Technology Data Exchange (ETDEWEB)

    Saikia, D. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); Chen-Yang, Y.W. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)], E-mail: yuiwhei@cycu.edu.tw; Chen, Y.T.; Li, Y.K.; Lin, S.I. [Department of Chemistry, Center for Nanotechnology and R and D Center for Membrane Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)

    2009-01-30

    Microporous composite gel polymer electrolyte (CGPE) has been prepared by incorporating the home-made silica aerogel (SAG) particles into the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer/LiClO{sub 4} matrix. The ionic transport behavior of the electrolyte is studied with various experimental techniques such as AC impedance, X-ray diffraction (XRD), infrared (IR) spectra, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA), etc. The results reveal that the SAG particles are well dispersed in the electrolytes and incorporate with the other components of the CGPEs. The solid-state {sup 7}Li NMR study has confirmed the interactions of lithium ion with SAG, polymer and plasticizers, causing to form the microporous structure and reduce the glass transition temperature and crystallinity, resulting in an increase in ionic conductivity of the CGPE. The best ionic conductivity (1.04 x 10{sup -2} S/cm at room temperature) is obtained from the composite polymer electrolyte containing 4 wt% of SAG, which is approximately four times higher than the ionic conductivity of the electrolyte without the filler.

  14. A Metabolomic Approach (1H HRMAS NMR Spectroscopy) Supported by Histology to Study Early Post-transplantation Responses in Islet-transplanted Livers

    Science.gov (United States)

    Vivot, Kevin; Benahmed, Malika A.; Seyfritz, Elodie; Bietiger, William; Elbayed, Karim; Ruhland, Elisa; Langlois, Allan; Maillard, Elisa; Pinget, Michel; Jeandidier, Nathalie; Gies, Jean-Pierre; Namer, Izzie-Jacques; Sigrist, Séverine; Reix, Nathalie

    2016-01-01

    Intrahepatic transplantation of islets requires a lot of islets because more than 50% of the graft is lost during the 24 hours following transplantation. We analyzed, in a rat model, early post-transplantation inflammation using systemic inflammatory markers, or directly in islet-transplanted livers by immunohistochemistry. 1H HRMAS NMR was employed to investigate metabolic responses associated with the transplantation. Inflammatory markers (Interleukin-6, α2-macroglobulin) are not suitable to follow islet reactions as they are not islet specific. To study islet specific inflammatory events, immunohistochemistry was performed on sections of islet transplanted livers for thrombin (indicator of the instant blood-mediated inflammatory reaction (IBMIR)) and granulocytes and macrophages. We observed a specific correlation between IBMIR and granulocyte and macrophage infiltration after 12 h. In parallel, we identified a metabolic response associated with transplantation: after 12 h, glucose, alanine, aspartate, glutamate and glutathione were significantly increased. An increase of glucose is a marker of tissue degradation, and could be explained by immune cell infiltration. Alanine, aspartate and glutamate are inter-connected in a common metabolic pathway known to be activated during hypoxia. An increase of glutathione revealed the presence of antioxidant protection. In this study, IBMIR visualization combined with 1H HRMAS NMR facilitated the characterization of cellular and molecular pathways recruited following islet transplantation. PMID:27766032

  15. 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

  16. Analysis and aging of unsaturated polyester resins in contemporary art installations by NMR spectroscopy.

    Science.gov (United States)

    Stamatakis, Georgios; Knuutinen, Ulla; Laitinen, Kai; Spyros, Apostolos

    2010-12-01

    Two original art installations constructed from unsaturated polyester resins (UPR) and four different reference UPR products (before and after UVB aging) were analyzed by high-resolution 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Breaking strain studies were also conducted for the four UPR model products before and after different aging procedures (moisture, UVB exposure, melt/freeze). NMR analysis of the chemical composition of the UPR resin extracts showed they contain several low MW organic compounds and oligomers rich in polar -OH groups that play a significant role in the degradation behavior of the composite UPR materials. Statistical analysis of the NMR compositional data showed that styrene and benzaldehyde contents can be used to differentiate between fresh and aged UPR samples. The phthalate and propylene glycol unit speciation (esterified, primary or secondary -OH) of the extracts provided evidence that UPR resin C was used in the construction of the two art installations, and direct comparison of (1)H and (13)C NMR spectra verified this compositional similarity. UPR resin C was shown by both NMR and breaking strain studies to be the reference UPR most susceptible to degradation by different aging procedures, a characteristic attributed to the lower styrene content of resin C.

  17. Synthesis, spectroscopy (vibrational, NMR and UV-vis) studies, HOMO-LUMO and NBO analysis of 8-formyl-7-hydroxy-4-methylcoumarin by ab initio calculations

    Science.gov (United States)

    Moghanian, Hassan; Mobinikhaledi, Akbar; Monjezi, Roya

    2013-11-01

    In this work, 8-formyl-7-hydroxy-4-methylcoumarin has been synthesized and characterized by elemental analysis, FT-IR, FT Raman, 1H NMR, 13C NMR and UV-vis spectra. The molecular geometry, harmonic vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C chemical shift values of the title compound in the ground state have been calculated by using Hartree-Fock (HF) and density functional methods (B3LYP) with 6-311++G(d,p) as basis set. The vibrational assignments of wave numbers were interpreted in terms of potential energy distribution (PED) analysis and the scaled B3LYP/6-311++G(d,p) results show the good agreement with the experimental values. The UV spectra of investigated compound were recorded in the region of 230-500 nm in chloroform solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) in gas and CHCl3 theoretically and results were compared with experimental observations. The molecular stability arising from hyperconjugative interactions and charge delocalization have been analyzed using natural bond orbital (NBO) analysis. In addition, Frontier Molecular Orbitals (FMO), Molecular Electrostatic Potential (MEP) and thermodynamic properties of the studied compound such as heat capacity (C), entropy (S) and enthalpy changes (H) at different temperatures have been calculated.

  18. {sup 13}CHD{sub 2}–CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins

    Energy Technology Data Exchange (ETDEWEB)

    Rennella, Enrico; Huang, Rui; Velyvis, Algirdas; Kay, Lewis E., E-mail: kay@pound.med.utoronto.ca [The University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)

    2015-10-15

    An NMR experiment for quantifying slow (millisecond) time-scale exchange processes involving the interconversion between visible ground state and invisible, conformationally excited state conformers is presented. The approach exploits chemical exchange saturation transfer (CEST) and makes use of {sup 13}CHD{sub 2} methyl group probes that can be readily incorporated into otherwise highly deuterated proteins. The methodology is validated with an application to a G48A Fyn SH3 domain that exchanges between a folded conformation and a sparsely populated and transiently formed unfolded ensemble. Experiments on a number of different protein systems, including a 360 kDa half-proteasome, establish that the sensitivity of this {sup 13}CHD{sub 2}{sup 13}C–CEST technique can be upwards of a factor of 5 times higher than for a previously published {sup 13}CH{sub 3}{sup 13}C–CEST approach (Bouvignies and Kay in J Biomol NMR 53:303–310, 2012), suggesting that the methodology will be powerful for studies of conformational exchange in high molecular weight proteins.

  19. Study of molecular interactions with 13C DNP-NMR.

    Science.gov (United States)

    Lerche, Mathilde H; Meier, Sebastian; Jensen, Pernille R; Baumann, Herbert; Petersen, Bent O; Karlsson, Magnus; Duus, Jens Ø; Ardenkjaer-Larsen, Jan H

    2010-03-01

    NMR spectroscopy is an established, versatile technique for the detection of molecular interactions, even when these interactions are weak. Signal enhancement by several orders of magnitude through dynamic nuclear polarization alleviates several practical limitations of NMR-based interaction studies. This enhanced non-equilibrium polarization contributes sensitivity for the detection of molecular interactions in a single NMR transient. We show that direct (13)C NMR ligand binding studies at natural isotopic abundance of (13)C gets feasible in this way. Resultant screens are easy to interpret and can be performed at (13)C concentrations below muM. In addition to such ligand-detected studies of molecular interaction, ligand binding can be assessed and quantified with enzymatic assays that employ hyperpolarized substrates at varying enzyme inhibitor concentrations. The physical labeling of nuclear spins by hyperpolarization thus provides the opportunity to devise fast novel in vitro experiments with low material requirement and without the need for synthetic modifications of target or ligands.

  20. Metabolic response to exogenous ethanol in yeast: an in vivo statistical total correlation NMR spectroscopy approach.

    Science.gov (United States)

    Ricci, Maso; Aggravi, Marianna; Bonechi, Claudia; Martini, Silvia; Aloisi, Anna Maria; Rossi, Claudio

    2012-09-01

    In vivo NMR spectroscopy, together with selectively 13C-labelled substrates and 'statistical total correlation spectroscopy' analysis (STOCSY), are valuable tools to collect and interpret the metabolic responses of a living organism to external stimuli. In this study, we applied this approach to evaluate the effects of increasing concentration of exogenous ethanol on the Saccharomyces cerevisiae fermentative metabolism. We show that the STOCSY analysis correctly identifies the different types of correlations among the enriched metabolites involved in the fermentation, and that these correlations are quite stable even in presence of a stressing factor such as the exogenous ethanol.

  1. In vivo and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study; Espectroscopia `in vivo` e de alta resolucao em solidos por RMN: uma ferramenta para o estudo de plantas transgenicas

    Energy Technology Data Exchange (ETDEWEB)

    Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R. [EMBRAPA (Brazil). Centro Nacional de Pesquisa de Defesa da Agricultura; Bonagamba, T.J.; Panepucci, H. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica; Carneiro, M.; Rodrigues, C.A. [EMBRAPA (CENARGEN) (Brazil)

    1995-12-31

    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 2 refs., 4 figs.

  2. Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cancilla, Mark; Lebrilla, Carlito; Ma, Jian-Guo; Medforth, Craig J.; Muzzi, Cinzia M.; Shelnutt, John A.; Smith, Kevin M.; Voss, Lisa

    1999-05-05

    An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) 1H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

  3. Solid state NMR study of bone mineral

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.

    1992-01-01

    In high field (9.4 T) CP MASS (cross polarization magic angle sample spinning) studies, in contrast to the scheme in the literature that infers the presence of minor constituents in spectra, we developed a new scheme to suppress the main part of the spectra to show the minor constituents. In order to perform in vivo solid state NMR studies, a double tuned two port surface coil probe was constructed. This probe is a modified version of the traditional Cross probe, which utilizes two 1/4 wave length 50 ohm transmission line, one with open ended and the other with shorted end, to isolate the high and low frequency circuits. The two resonance frequencies in Cross probe were proton and carbon. Our probe is designed to resonate at the proton and phosphorus frequencies, which are much closer to each other and hence more difficult to be tuned and matched simultaneously. Our approach to solve this problem is that instead of using standard 50 ohm transmission lines, we constructed a low capacity open end coaxial transmission line and low inductance shorted end coaxial transmission line. The Q of the phosphorus channel is high. We developed a short contact time cross polarization technique for non-MASS spectroscopy which reduces the signal of the major component of bone mineral to emphasize the minor component. By applying this technique on intact pork bone samples with our home made surface coil, we observed the wide line component, acid phosphate, for the first time. Hydroxyapatite, brushite and octacalcium are considered in the literature to be the model compounds for bone mineral. Cross polarization dynamics has been studied on hydroxyapatite and brushite, which yielded an NMR value for the distance between proton and phosphorus. One and two dimensional CP MASS spectroscopy of octacalcium phosphate were also studied, which revealed the different cross polarization rates and anisotropic channel shifts of acid phosphate and phosphate ions in octacalcium phosphate.

  4. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    Science.gov (United States)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (γ), such as protons, to the less abundant 13C nuclei with low γ values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; Kögel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90° x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-05-01

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

  7. Concepts and Methods of Solid-State NMR Spectroscopy Applied to Biomembranes.

    Science.gov (United States)

    Molugu, Trivikram R; Lee, Soohyun; Brown, Michael F

    2017-09-14

    Concepts of solid-state NMR spectroscopy and applications to fluid membranes are reviewed in this paper. Membrane lipids with (2)H-labeled acyl chains or polar head groups are studied using (2)H NMR to yield knowledge of their atomistic structures in relation to equilibrium properties. This review demonstrates the principles and applications of solid-state NMR by unifying dipolar and quadrupolar interactions and highlights the unique features offered by solid-state (2)H NMR with experimental illustrations. For randomly oriented multilamellar lipids or aligned membranes, solid-state (2)H NMR enables direct measurement of residual quadrupolar couplings (RQCs) due to individual C-(2)H-labeled segments. The distribution of RQC values gives nearly complete profiles of the segmental order parameters SCD((i)) as a function of acyl segment position (i). Alternatively, one can measure residual dipolar couplings (RDCs) for natural abundance lipid samples to obtain segmental SCH order parameters. A theoretical mean-torque model provides acyl-packing profiles representing the cumulative chain extension along the normal to the aqueous interface. Equilibrium structural properties of fluid bilayers and various thermodynamic quantities can then be calculated, which describe the interactions with cholesterol, detergents, peptides, and integral membrane proteins and formation of lipid rafts. One can also obtain direct information for membrane-bound peptides or proteins by measuring RDCs using magic-angle spinning (MAS) in combination with dipolar recoupling methods. Solid-state NMR methods have been extensively applied to characterize model membranes and membrane-bound peptides and proteins, giving unique information on their conformations, orientations, and interactions in the natural liquid-crystalline state.

  8. Methyl labeling and TROSY NMR spectroscopy of proteins expressed in the eukaryote Pichia pastoris

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Lindsay; Zahm, Jacob A.; Ali, Rustam [University of Texas Southwestern Medical Center, Department of Biophysics (United States); Kukula, Maciej; Bian, Liangqiao [University of Texas at Arlington, Shimadzu Center for Advanced Analytical Chemistry (United States); Patrie, Steven M. [University of Texas Southwestern Medical Center, Department of Pathology (United States); Gardner, Kevin H. [CUNY Advanced Science Research Center, Structural Biology Initiative (United States); Rosen, Michael K.; Rosenbaum, Daniel M., E-mail: dan.rosenbaum@utsouthwestern.edu [University of Texas Southwestern Medical Center, Department of Biophysics (United States)

    2015-07-15

    {sup 13}C Methyl TROSY NMR spectroscopy has emerged as a powerful method for studying the dynamics of large systems such as macromolecular assemblies and membrane proteins. Specific {sup 13}C labeling of aliphatic methyl groups and perdeuteration has been limited primarily to proteins expressed in E. coli, preventing studies of many eukaryotic proteins of physiological and biomedical significance. We demonstrate the feasibility of efficient {sup 13}C isoleucine δ1-methyl labeling in a deuterated background in an established eukaryotic expression host, Pichia pastoris, and show that this method can be used to label the eukaryotic protein actin, which cannot be expressed in bacteria. This approach will enable NMR studies of previously intractable targets.

  9. Characterization of metabolites in different kiwifruit varieties by NMR and fluorescence spectroscopy.

    Science.gov (United States)

    Abdul Hamid, Nur Ashikin; Mediani, Ahmed; Maulidiani, M; Abas, Faridah; Park, Yong Seo; Leontowicz, Hanna; Leontowicz, Maria; Namiesnik, Jacek; Gorinstein, S

    2017-05-10

    It is known from our previous studies that kiwifruits, which are used in common human diet, have preventive properties of coronary artery disease. This study describes a combination of (1)H NMR spectroscopy, multivariate data analyses and fluorescence measurements in differentiating of some kiwifruit varieties, their quenching and antioxidant properties. A total of 41 metabolites were identified by comparing with literature data Chenomx database and 2D NMR. The binding properties of the extracted polyphenols against HSA showed higher reactivity of studied two cultivars in comparison with the common Hayward. The results showed that the fluorescence of HSA was quenched by Bidan as much as twice than by other fruits. The correlation between the binding properties of polyphenols in the investigated fruits, their relative quantification and suggested metabolic pathway was established. These results can provide possible application of fruit extracts in pharmaceutical industry.

  10. Dynamic processes and chemical composition of Lepidium sativum seeds determined by means of field-cycling NMR relaxometry and NMR spectroscopy.

    Science.gov (United States)

    Rachocki, A; Latanowicz, L; Tritt-Goc, J

    2012-12-01

    Proton nuclear magnetic resonance (NMR) techniques, such as field-cycling relaxometry, wide-line NMR spectroscopy, and magic angle spinning NMR spectroscopy, were applied to study the seeds of cress, Lepidium sativum. Field-cycling NMR relaxometry was used for the first time to investigate the properties of the whole molecular system of dry cress seeds. This method not only allowed the dynamics to be studied, but was also successful in the differentiation among the solid (i.e., carbohydrates, proteins, or fats forming a solid form of lipids) and liquid-like (oil compounds) components of the seeds. The (1)H NMR relaxation dispersion of oils was interpreted as a superposition of intramolecular and intermolecular contributions. The intramolecular part was described in terms of a Lorentzian spectral density function, whereas a log-Gaussian distribution of correlation times was applied for the intermolecular dipole-dipole contribution. The models applied led to very good agreement with the experimental data and demonstrate that the contribution of the intermolecular relaxation to the overall relaxation should not be disregarded, especially at low frequencies. A power-law frequency dependence of the proton relaxation dispersion was used for the interpretation of the solid components. From the analysis of the (1)H wide-line NMR spectra of the liquid-like component of hydrated cress seeds, we can conclude that the contribution of oil protons should always be taken into account when evaluating the spin-lattice relaxation times values or measuring the moisture and oil content. The application of (1)H magic angle spinning NMR significantly improves resolution in the liquid-like spectrum of seeds and allows the determination of the chemical composition of cress seeds.

  11. Characterization of the insertase BamA in three different membrane mimetics by solution NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Leonor; Zeth, Kornelius; Burmann, Björn M.; Maier, Timm; Hiller, Sebastian, E-mail: sebastian.hiller@unibas.ch [University of Basel, Biozentrum (Switzerland)

    2015-04-15

    The insertase BamA is the central protein of the Bam complex responsible for outer membrane protein biogenesis in Gram-negative bacteria. BamA features a 16-stranded transmembrane β-barrel and five periplasmic POTRA domains, with a total molecular weight of 88 kDa. Whereas the structure of BamA has recently been determined by X-ray crystallography, its functional mechanism is not well understood. This mechanism comprises the insertion of substrates from a dynamic, chaperone-bound state into the bacterial outer membrane, and NMR spectroscopy is thus a method of choice for its elucidation. Here, we report solution NMR studies of different BamA constructs in three different membrane mimetic systems: LDAO micelles, DMPC:DiC{sub 7}PC bicelles and MSP1D1:DMPC nanodiscs. The impact of biochemical parameters on the spectral quality was investigated, including the total protein concentration and the detergent:protein ratio. The barrel of BamA is folded in micelles, bicelles and nanodiscs, but the N-terminal POTRA5 domain is flexibly unfolded in the absence of POTRA4. Measurements of backbone dynamics show that the variable insertion region of BamA, located in the extracellular lid loop L6, features high local flexibility. Our work establishes biochemical preparation schemes for BamA, which will serve as a platform for structural and functional studies of BamA and its role within the Bam complex by solution NMR spectroscopy.

  12. Characterization of the insertase BamA in three different membrane mimetics by solution NMR spectroscopy.

    Science.gov (United States)

    Morgado, Leonor; Zeth, Kornelius; Burmann, Björn M; Maier, Timm; Hiller, Sebastian

    2015-04-01

    The insertase BamA is the central protein of the Bam complex responsible for outer membrane protein biogenesis in Gram-negative bacteria. BamA features a 16-stranded transmembrane β-barrel and five periplasmic POTRA domains, with a total molecular weight of 88 kDa. Whereas the structure of BamA has recently been determined by X-ray crystallography, its functional mechanism is not well understood. This mechanism comprises the insertion of substrates from a dynamic, chaperone-bound state into the bacterial outer membrane, and NMR spectroscopy is thus a method of choice for its elucidation. Here, we report solution NMR studies of different BamA constructs in three different membrane mimetic systems: LDAO micelles, DMPC:DiC7PC bicelles and MSP1D1:DMPC nanodiscs. The impact of biochemical parameters on the spectral quality was investigated, including the total protein concentration and the detergent:protein ratio. The barrel of BamA is folded in micelles, bicelles and nanodiscs, but the N-terminal POTRA5 domain is flexibly unfolded in the absence of POTRA4. Measurements of backbone dynamics show that the variable insertion region of BamA, located in the extracellular lid loop L6, features high local flexibility. Our work establishes biochemical preparation schemes for BamA, which will serve as a platform for structural and functional studies of BamA and its role within the Bam complex by solution NMR spectroscopy.

  13. A complete vibrational study on a potential environmental toxicant agent, the 3,3',4,4'-tetrachloroazobenzene combining the FTIR, FTRaman, UV-Visible and NMR spectroscopies with DFT calculations.

    Science.gov (United States)

    Castillo, María V; Pergomet, Jorgelina L; Carnavale, Gustavo A; Davies, Lilian; Zinczuk, Juan; Brandán, Silvia A

    2015-01-05

    In this study 3,3',4,4'-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared, Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopies. The density functional theory (DFT) together with the 6-31G(*) and 6-311++G(**) basis sets were used to study the structures and vibrational properties of the two cis and trans isomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. A complete assignment of all the observed bands in the vibrational spectra of TCAB was performed combining the DFT calculations with the scaled quantum mechanical force field (SQMFF) methodology. The molecular electrostatic potentials, atomic charges, bond orders and frontier orbitals for the two isomers of TCAB were compared and analyzed. The comparison of the theoretical ultraviolet-visible spectrum with the corresponding experimental demonstrates a good concordance while the calculated (1)H and (13)C chemicals shifts are in good conformity with the corresponding experimental NMR spectra of TCAB in solution. The npp(*) transitions for both forms were studied by natural bond orbital (NBO) while the topological properties were calculated by employing Bader's Atoms in the Molecules (AIM) theory. This study shows that the cis and trans isomers exhibit different structural and vibrational properties and absorption bands. Copyright © 2014. Published by Elsevier B.V.

  14. Characterizations of Some N-Substituted-salicylhydrazide in Mixtures by NMR Diffusion Ordered Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    张芳; 于贤勇; 陈忠; 林深; 刘世雄

    2003-01-01

    Several novel N-substituted-salicylhydrazide ligands, most of which are difficult to be purified or recrystallized so that their chemical configurations can not be confirmed by conventional NMR and/or X-ray diffraction techniques, were synthesized in this experiment, and their chemical configurations in mixture were analyzed and characterized by 2D NMR diffusion ordered spectroscopy (DOSY), a labor-saving virtual separation based on diffusion properties,together with several routine NMR techniques.

  15. Integration of screening and identifying ligand(s) from medicinal plant extracts based on target recognition by using NMR spectroscopy

    OpenAIRE

    2015-01-01

    Authors: Yalin Tang, Qian Shang, Junfeng Xiang, Qianfan Yang, Qiuju Zhou, Lin Li, Hong Zhang, Qian Li, Hongxia Sun, Aijiao Guan, Wei Jiang & Wei Gai ### Abstract This protocol presents the screening of ligand(s) from medicinal plant extracts based on target recognition by using NMR spectroscopy. A detailed description of sample preparation and analysis process is provided. NMR spectroscopies described here are 1H NMR, diffusion-ordered spectroscopy (DOSY), relaxation-edited NMR, ...

  16. NMR studies of actinide dioxides

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-11

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

  17. Determination of the biogenic secondary organic aerosol fraction in the boreal forest by NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    E. Finessi

    2012-01-01

    Full Text Available The study investigates the sources of fine organic aerosol (OA in the boreal forest, based on measurements including both filter sampling (PM1 and online methods and carried out during a one-month campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS were employed to measure on-line concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions.

    The NMR results supported the AMS speciation of oxidized organic aerosol (OOA into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls. Such component, contributing on average 50% of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated with the formation of terrestrial biogenic secondary organic aerosol (BSOA, based on the comparison with spectral profiles obtained from laboratory experiments of

  18. LEGO-NMR spectroscopy: a method to visualize individual subunits in large heteromeric complexes.

    Science.gov (United States)

    Mund, Markus; Overbeck, Jan H; Ullmann, Janina; Sprangers, Remco

    2013-10-18

    Seeing the big picture: Asymmetric macromolecular complexes that are NMR active in only a subset of their subunits can be prepared, thus decreasing NMR spectral complexity. For the hetero heptameric LSm1-7 and LSm2-8 rings NMR spectra of the individual subunits of the complete complex are obtained, showing a conserved RNA binding site. This LEGO-NMR technique makes large asymmetric complexes accessible to detailed NMR spectroscopic studies.

  19. NMR Spectroscopy of Human Eye Tissues: A New Insight into Ocular Biochemistry

    Directory of Open Access Journals (Sweden)

    Tomasz Kryczka

    2014-01-01

    Full Text Available Background. The human eye is a complex organ whose anatomy and functions has been described very well to date. Unfortunately, the knowledge of the biochemistry and metabolic properties of eye tissues varies. Our objective was to reveal the biochemical differences between main tissue components of human eyes. Methods. Corneas, irises, ciliary bodies, lenses, and retinas were obtained from cadaver globes 0-1/2 hours postmortem of 6 male donors (age: 44–61 years. The metabolic profile of tissues was investigated with HR MAS 1H NMR spectroscopy. Results. A total of 29 metabolites were assigned in the NMR spectra of the eye tissues. Significant differences between tissues were revealed in contents of the most distant eye-tissues, while irises and ciliary bodies showed minimal biochemical differences. ATP, acetate, choline, glutamate, lactate, myoinositol, and taurine were identified as the primary biochemical compounds responsible for differentiation of the eye tissues. Conclusions. In this study we showed for the first time the results of the analysis of the main human eye tissues with NMR spectroscopy. The biochemical contents of the selected tissues seemed to correspond to their primary anatomical and functional attributes, the way of the delivery of the nutrients, and the location of the tissues in the eye.

  20. Carbon-dot organic surface modifier analysis by solution-state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Philippidis, Aggelos; Spyros, Apostolos, E-mail: aspyros@chemistry.uoc.gr; Anglos, Demetrios [University of Crete, NMR Laboratory, Department of Chemistry (Greece); Bourlinos, Athanasios B. [University of Ioannina, Physics Department (Greece); Zboril, Radek [Palacky University in Olomouc, Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (Czech Republic); Giannelis, Emmanuel P. [Cornell University, Department of Materials Science and Engineering (United States)

    2013-07-15

    Carbon dots (C-dots) represent a new class of carbon-based materials that were discovered recently and have drawn the interest of the scientific community, particularly because of their attractive optical properties and their potential as fluorescent sensors. Investigation of the chemical structure of C-dots is extremely important for correlating the surface modifier composition with C-dot optical properties and allow for structure-properties fine tuning. In this article, we report the structural analysis of the surface modifiers of three different types of C-dot nanoparticles (Cwax, Cws, and Csalt) by use of 1D- and 2D-high-resolution NMR spectroscopy in solution. We unambiguously verify that the structure of the modifier chains remains chemically unchanged during the passivation procedure, and confirm the covalent attachment of the modifiers to the nanoparticle core, which contributes no signal to the solution-state NMR spectra. To our knowledge, this is the first study confirming the full structural assignment of C-dot organic surface modifiers by use of solution NMR spectroscopy.

  1. Development of a micro flow-through cell for high field NMR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd Michael; McIntyre, Sarah K.

    2011-05-01

    A highly transportable micro flow-through detection cell for nuclear magnetic resonance (NMR) spectroscopy has been designed, fabricated and tested. This flow-through cell allows for the direct coupling between liquid chromatography (LC) and gel permeation chromatography (GPC) resulting in the possibility of hyphenated LC-NMR and GPC-NMR. The advantage of the present flow cell design is that it is independent and unconnected to the detection probe electronics, is compatible with existing commercial high resolution NMR probes, and as such can be easily implemented at any NMR facility. Two different volumes were fabricated corresponding to between {approx}3.8 and 10 {micro}L detection volume. Examples of the performance of the cell on different NMR instruments, and using different NMR detection probes were demonstrated.

  2. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    Science.gov (United States)

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  3. Structure elucidation of glycoprotein glycans and of polysaccharides by NMR spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Leeflang, B.R.; Faber, E.J.; Erbel, P.J.A.

    2000-01-01

    The applicability of 1H-NMR spectroscopy for the determination of the primary and tertiary structure of carbohydrate-containing molecules is demonstrated. For classes of known compounds the characterization can be based on chemical shifts observed in 1D NMR spectra with or without the aid of a compu

  4. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    Science.gov (United States)

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  5. ' q-Titration' of long-chain and short-chain lipids differentiates between structured and mobile residues of membrane proteins studied in bicelles by solution NMR spectroscopy

    Science.gov (United States)

    Son, Woo Sung; Park, Sang Ho; Nothnagel, Henry J.; Lu, George J.; Wang, Yan; Zhang, Hua; Cook, Gabriel A.; Howell, Stanley C.; Opella, Stanley J.

    2012-01-01

    ' q-Titration' refers to the systematic comparison of signal intensities in solution NMR spectra of uniformly 15N labeled membrane proteins solubilized in micelles and isotropic bicelles as a function of the molar ratios ( q) of the long-chain lipids (typically DMPC) to short-chain lipids (typically DHPC). In general, as q increases, the protein resonances broaden and correspondingly have reduced intensities due to the overall slowing of protein reorientation. Since the protein backbone signals do not broaden uniformly, the differences in line widths (and intensities) enable the narrower (more intense) signals associated with mobile residues to be differentiated from the broader (less intense) signals associated with "structured" residues. For membrane proteins with between one and seven trans-membrane helices in isotropic bicelles, we have been able to find a value of q between 0.1 and 1.0 where only signals from mobile residues are observed in the spectra. The signals from the structured residues are broadened so much that they cannot be observed under standard solution NMR conditions. This q value corresponds to the ratio of DMPC:DHPC where the signals from the structured residues are "titrated out" of the spectrum. This q value is unique for each protein. In magnetically aligned bilayers ( q > 2.5) no signals are observed in solution NMR spectra of membrane proteins because the polypeptides are "immobilized" by their interactions with the phospholipid bilayers on the relevant NMR timescale (˜10 5 Hz). No signals are observed from proteins in liposomes (only long-chain lipids) either. We show that it is feasible to obtain complementary solution NMR and solid-state NMR spectra of the same membrane protein, where signals from the mobile residues are present in the solution NMR spectra, and signals from the structured residues are present in the solid-state NMR spectra. With assigned backbone amide resonances, these data are sufficient to describe major features

  6. The neurochemical profile quantified by in vivo(1)H NMR spectroscopy

    OpenAIRE

    João M N Duarte; Lei, Hongxia; Mlynárik, Vladimír; Gruetter, Rolf

    2012-01-01

    Proton NMR spectroscopy is emerging from translational and preclinical neuroscience research as an important tool for evidence based diagnosis and therapy monitoring. It provides biomarkers that offer fingerprints of neurological disorders even in cases where a lesion is not yet observed in MR images. The collection of molecules used as cerebral biomarkers that are detectable by (1)H NMR spectroscopy define the so-called "neurochemical profile". The non-invasive quality of this technique make...

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

    KAUST Repository

    Pump, Eva

    2016-08-15

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

  8. Classification of Wines Based on Combination of 1H NMR Spectroscopy and Principal Component Analysis

    Institute of Scientific and Technical Information of China (English)

    DU, Yuan-Yuan; BAI, Guo-Yun; ZHANG, Xu; LIU, Mai-Li

    2007-01-01

    A combination of 1H nuclear magnetic resonance (NMR) spectroscopy and principal component analysis (PCA)has shown the potential for being a useful method for classification of type, production origin or geographic origin of wines. In this preliminary study, twenty-one bottled wines were classified/separated for their location of production in Shacheng, Changli and Yantai, and the types of the blended, medium dry, dry white and dry red wines, using the NMR-PCA method. The wines were produced by three subsidiary companies of an enterprise according to the same national standard. The separation was believed to be mainly due to the fermentation process for different wines and environmental variations, such as local climate, soil, underground water, sunlight and rainfall. The major chemicals associated with the separation were identified.

  9. Metabolic Profiling of Food Protective Cultures by in vitro NMR Spectroscopy

    DEFF Research Database (Denmark)

    Ebrahimi, Parvaneh

    D project is mainly focused on the application of in vitro NMR spectroscopy for studying the metabolism of protective cultures. As an important part of this work, an analytical protocol was developed for realtime in vitro NMR measurements of bacterial fermentation, which includes guidelines from the sample......Food spoilage is of major concern to the food industry, because it leads to considerable economic losses, a deteriorated environmental food-print, and to possible public health hazards. In order to limit food spoilage, research on the preservation of food products has always received particular......-called protective cultures) has unexploited potential to inhibit the growth of pathogenic microorganisms and enhance the shelf life of the final food product. In order to apply biopreservation in food products effectively, detailed knowledge on the metabolism of protective cultures is required. The present Ph...

  10. Beckmann rearrangement of 15N-cyclohexanone oxime on zeolites silicalite-1, H-ZSM-5, and H-[B]ZSM-5 studied by solid-state NMR spectroscopy.

    Science.gov (United States)

    Marthala, V R Reddy; Jiang, Yijiao; Huang, Jun; Wang, Wei; Gläser, Roger; Hunger, Michael

    2006-11-22

    By means of solid-state 15N NMR spectroscopy, evidence for the formation of nitrilium ions as intermediates of the Beckmann rearrangement of 15N-cyclohexanone oxime to epsilon-caprolactam on silicalite-1, H-ZSM-5, and H-[B]ZSM-5 is reported. The zeolites under study are characterized by different acid strengths (silicalite-1 < H-[B]ZSM-5 < H-ZSM-5). Depending on the nature of catalytically active surface OH groups, reactant and product molecules exist in the nonprotonated or protonated state. In addition, formation of byproducts such as 5-cyano-1-pentene and epsilon-aminocapric acid as a result of dehydration and hydrolysis of the reactant and product molecules, respectively, were observed.

  11. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Yiung- Il [UCSB; Cadars, Sylvian [UCSB; Shayib, Ramzy [UCSB; Feigerle, Charles S [UNIV OF TENNESSEE; Chmelka, Bradley F [UCSB; Seshadri, Ram [UCSB

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  12. Bringing NMR and IR Spectroscopy to High Schools

    Science.gov (United States)

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

    2017-01-01

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

  13. Bringing NMR and IR Spectroscopy to High Schools

    Science.gov (United States)

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

    2017-01-01

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

  14. Advanced solid-state NMR spectroscopy of natural organic matter

    Science.gov (United States)

    Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially the systematic approach to NOM characterization, and their ...

  15. Functional groups identified by solid state 13C NMR spectroscopy

    Science.gov (United States)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  16. (17)O NMR and Raman Spectroscopies of Green Tea Infusion with Nanomaterial to Investigate Their Properties.

    Science.gov (United States)

    Zhou, Changyan; Zhang, Huiping; Yan, Ying; Zhang, Xinya

    2016-09-01

    (17)O NMR and Raman spectrograms of green tea infusions with nanomaterial were investigated. Different green tea infusions were prepared by steeping tea powder with different concentrations of nanomaterial aqueous solution. The tea infusions were tested with (17)O NMR and Raman spectroscopies. The (17)O NMR results showed that line width increased to 90 in the tea infusions after nanomaterial was added as a result of the effects of the self-association of Ca(2+) and tea polyphenol. The results of Raman spectroscopy showed that, in tea infusions, the enhancement of C─C and C─O stretching vibrations suggest an increase in the number of effective components in water.

  17. Interaction between dry starch and plasticisers glycerol or ethylene glycol, measured by differential scanning calorimetry and solid state NMR spectroscopy

    NARCIS (Netherlands)

    Smits, A.L.M.; Kruiskamp, P.H.; Soest, van J.J.G.; Vliegenthart, J.F.G.

    2003-01-01

    The interaction of crystalline amylose and of crystalline and amorphous amylopectin with the plasticisers glycerol or ethylene glycol in the absence of water was studied, by using differential scanning calorimetry (DSC) and solid state nuclear magnetic resonance (NMR) spectroscopy. Upon heating

  18. Labelling analysis for ¹³C MFA using NMR spectroscopy.

    Science.gov (United States)

    Jouhten, Paula; Maaheimo, Hannu

    2014-01-01

    NMR spectroscopy is an efficient method for analyzing (13)C labelling of cellular metabolites. The strength of it is especially the ability to provide direct quantitative positional information on the (13)C labelling status of carbon atoms in metabolites. NMR spectroscopic methods allow also for detection of contiguously (13)C-labelled fragments in the carbon backbones of the metabolites. Furthermore, the recent developments of NMR spectroscopy hardware have substantially improved the sensitivity of the methods. In this chapter we describe a method for analyzing the (13)C labelling of the biomass amino acids for metabolic flux analysis, sample preparation for NMR spectroscopy, acquiring and processing the NMR spectra, and extracting the (13)C labelling information from the NMR data. Different NMR methods are applied depending on the (13)C labelling strategy chosen. These strategies include uniform (13)C labelling, positional (13)C labelling, or a combination of both. Not only the preparation of sample for analysis of (13)C labelling in proteinogenic amino acids in biomass is described, but also the necessary modifications to the method when analysis of (13)C labelling in free metabolic intermediates is of interest. Finally the strategies for using the different NMR-detected (13)C labelling data in (13)C MFA are discussed.

  19. Metabolic response to exogenous ethanol in yeast: An in vivo statistical total correlation NMR spectroscopy approach

    Indian Academy of Sciences (India)

    Maso Ricci; Marianna Aggravi; Claudia Bonechi; Silvia Martini; Anna Maria; Claudio Rossi

    2012-09-01

    In vivo NMR spectroscopy, together with selectively 13C-labelled substrates and ‘statistical total correlation spectroscopy’ analysis (STOCSY), are valuable tools to collect and interpret the metabolic responses of a living organism to external stimuli. In this study, we applied this approach to evaluate the effects of increasing concentration of exogenous ethanol on the Saccharomyces cerevisiae fermentative metabolism. We show that the STOCSY analysis correctly identifies the different types of correlations among the enriched metabolites involved in the fermentation, and that these correlations are quite stable even in presence of a stressing factor such as the exogenous ethanol.

  20. Stereochemical investigations on the diketopiperazine derivatives of enalapril and lisinopril by NMR spectroscopy

    Science.gov (United States)

    Demeter, Ádám; Fodor, Tamás; Fischer, János

    1998-11-01

    Stereochemical analysis of epimeric diketopiperazine (DKP) derivatives of enalapril and lisinopril has been performed by NMR spectroscopy. The present study focuses on the configurational assignment and conformational characteristics of the epimeric DKPs obtained from cyclization and subsequent base-catalyzed hydrolysis. We report full 1H and 13C assignments as obtained by a concerted use of 1D and 2D methods. The configuration of the respective stereogenic centres and the main conformational features were derived from the measured scalar and NOE connections. One conspicuous conformational feature of the sidechain is its tendency to bend over the piperazinedione ring.

  1. Infrared spectroscopy as a tool to characterise starch ordered structure--a joint FTIR-ATR, NMR, XRD and DSC study.

    Science.gov (United States)

    Warren, Frederick J; Gidley, Michael J; Flanagan, Bernadine M

    2016-03-30

    Starch has a heterogeneous, semi-crystalline granular structure and the degree of ordered structure can affect its behaviour in foods and bioplastics. A range of methodologies are employed to study starch structure; differential scanning calorimetry, (13)C nuclear magnetic resonance, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Despite the appeal of FTIR as a rapid, non-destructive methodology, there is currently no systematically defined quantitative relationship between FTIR spectral features and other starch structural measures. Here, we subject 61 starch samples to structural analysis, and systematically correlate FTIR spectra with other measures of starch structure. A hydration dependent peak position shift in the FTIR spectra of starch is observed, resulting from increased molecular order, but with complex, non-linear behaviour. We demonstrate that FTIR is a tool that can quantitatively probe short range interactions in starch structure. However, the assumptions of linear relationships between starch ordered structure and peak ratios are overly simplistic.

  2. Ultra fast magic angle spinning solid - state NMR spectroscopy of intact bone.

    Science.gov (United States)

    Singh, Chandan; Rai, Ratan Kumar; Kayastha, Arvind M; Sinha, Neeraj

    2016-02-01

    Ultra fast magic angle spinning (MAS) has been a potent method to significantly average out homogeneous/inhomogeneous line broadening in solid-state nuclear magnetic resonance (ssNMR) spectroscopy. It has given a new direction to ssNMR spectroscopy with its different applications. We present here the first and foremost application of ultra fast MAS (~60 kHz) for ssNMR spectroscopy of intact bone. This methodology helps to comprehend and elucidate the organic content in the intact bone matrix with resolution and sensitivity enhancement. At this MAS speed, amino protons from organic part of intact bone start to appear in (1) H NMR spectra. The experimental protocol of ultra-high speed MAS for intact bone has been entailed with an additional insight achieved at 60 kHz.

  3. Study by ³¹P NMR spectroscopy of the triacylglycerol degradation processes in olive oil with different heat-transfer mechanisms.

    Science.gov (United States)

    Lucas-Torres, Covadonga; Pérez, Angel; Cabañas, Beatriz; Moreno, Andrés

    2014-12-15

    The thermal degradation of olive oil using conventional and microwave heating under the same experimental conditions were compared. A powerful identification and quantification technique based on (31)P NMR has been developed to characterise the differences between the minor components including diacylglycerol and free fatty acids in the heated samples. The (31)P NMR spectra of the degraded olive oils, which contain OH groups derivatised with a phosphorus reagent, showed that conventional heating is more detrimental to the oil than microwave technique. Conventional heating leads to a significant increase in the diacylglycerol and free fatty acid contents as well as in the number of degradation compounds, which damage the olive oil quality. However, the main process that takes place on using microwave heating is isomerisation between diacylglycerols, a change that could give a potential longer shelf life to the olive oil.

  4. Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, David Joel [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    NMR spectroscopy is ideal for studying weak interactions (formation enthalpy ≤20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*2Yb, is ideal for this purpose. cis-P2PtH2complexes (P = phosphine) were used to produce slow-exchange Cp*2YbL adducts for NMR study. Reversible formation of (P2PtH)2 complexes from cis-P2PtH2 complexes were also studied, followed by interactions of Cp*2Yb with phosphines, R3PX complexes. A NMR study was done on the interactions of Cp*2Yb with H2, CH4, Xe, CO, silanes, stannanes, C6H6, and toluene.

  5. Observations of Quantum Dynamics by Solution-State NMR Spectroscopy

    CERN Document Server

    Pravia, M A; Weinstein, Yu S; Price, M D; Teklemariam, G; Nelson, R J; Sharf, Y; Somaroo, S S; Tseng, C H; Havel, T F; Cory, D G

    1999-01-01

    NMR is emerging as a valuable testbed for the investigation of foundational questions in quantum mechanics. The present paper outlines the preparation of a class of mixed states, called pseudo-pure states, that emulate pure quantum states in the highly mixed environment typically used to describe solution-state NMR samples. It also describes the NMR observation of spinor behavior in spin 1/2 nuclei, the simulation of wave function collapse using a magnetic field gradient, the creation of entangled (or Bell) pseudo-pure states, and a brief discussion of quantum computing logic gates, including the Quantum Fourier Transform. These experiments show that liquid-state NMR can be used to demonstrate quantum dynamics at a level suitable for laboratory exercises.

  6. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β—Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    KaiJunLIAO; XiaoHuaYAN; 等

    2002-01-01

    The inclusion complex of lappaconitine(Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR,2D-NMR spectroscopy. The structure of the complex has been deduced.

  7. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β-Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The inclusion complex of lappaconitine (Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR, 2D-NMR spectroscopy.The structure of the complex has been deduced.``

  8. A comparative study of dynamic NMR spectroscopy in analysis of selected N-alkyl-, N-acyl-, and halogenated cytisine derivatives

    Science.gov (United States)

    Przybył, Anna K.; Kubicki, Maciej

    2011-01-01

    New halogenated derivatives of (-)-cytisine were synthesized: 3-bromo- N-acetylcytisine, 5-bromo- N-acetylcytisine, 3,5-dibromo- N-acetylcytisine, 3-iodo- N-acetylcytisine, 5-iodo- N-acetylcytisine, 3,5-diiodo- N-acetylcytisine. Their structures were established on the basis of their NMR spectra and X-ray diffraction method. The crystal structures confirmed the chair conformation of ring C, while in solution all these compounds are in cis-trans conformational equilibrium with ring C in chair and boat conformation. Additionally, the correct X-ray structure of N-benzylcytisine was resolved.

  9. Li mobility in fast ion conductors followed by NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, J.

    2010-07-01

    Structural features that enhance Li mobility in fast ion conductors with perovskite (Li{sub 3}xLa{sub 2}/3-xTiO{sub 3} series) and Nasicon structure (Li{sub 1}+xTi{sub 2}-xAl{sub x} (PO{sub 4}){sub 3} series) have been investigated. From the analysis of quadrupolar interactions, the local symmetry and exchange processes between structural sites occupied by lithium have been deduced to investigate local motions of lithium in conduction paths of analyzed compounds. The study of spin-lattice (T{sub 1}) and spin-spin (T{sub 2}) relaxation times made possible the analysis of the temperature dependence of Li residence times at structural sites. The comparison of these values with those deduced from conductivity (ac and dc-measurements) allowed the study of Li-motion mechanisms. The onset of long range motions requires the analysis of low frequency measurements (T{sub 2} relaxation and dc-conductivity). The non- Arrhenius behaviour, often observed in fast ion conductors, has been ascribed to order/disorder transitions. At increasing temperatures, Li motions become less correlated, producing the decrement of activation energy. In analyzed compounds, a direct measurement of diffusion coefficients has been obtained from NMR experiments performed with the pulse field gradient (PFG) technique. Finally, it is emphasized the importance of the vacancy percolation in conductivity processes. (Author)

  10. Investigating the Hydrolysis Reactions of a Chemical Warfare Agent Surrogate. A Systematic Study using 1H, 13C, 17O, 19F, 31P, and 35Cl NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wilson, Brendan W. [West Virginia Univ., Morgantown, WV (United States)

    2015-07-24

    During the summer of 2015, I participated in the DHS HS-STEM fellowship at Sandia National Laboratories (SNL, NM) under the supervision of Dr. Todd M. Alam in his Nuclear Magnetic Resonance (NMR) Spectroscopy research group. While with the group, my main project involved pursing various hydrolysis reactions with Diethyl Chlorophosphate (DECP), a surrogate for the agent Sarin (GB). Specifically, I performed different hydrolysis reactions, monitored and tracked the different phosphorous containing species using phosphorous (31P) NMR spectroscopy. With the data collected, I performed kinetics studies mapping the rates of DECP hydrolysis. I also used the NMR of different nuclei such as 1H, 13C, 17O, and 35Cl to help understand the complexity of the reactions that take place. Finally, my last task at SNL was to work with Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) NMR Spectroscopy optimizing conditions for 19F- 31P filtering NMR experiments.

  11. Sensitivity and resolution enhancement in solid-state NMR spectroscopy of bicelles

    Science.gov (United States)

    Dvinskikh, Sergey V.; Yamamoto, Kazutoshi; Dürr, Ulrich H. N.; Ramamoorthy, Ayyalusamy

    2007-02-01

    Magnetically aligned bicelles are becoming attractive model membranes to investigate the structure, dynamics, geometry, and interaction of membrane-associated peptides and proteins using solution- and solid-state NMR experiments. Recent studies have shown that bicelles are more suitable than mechanically aligned bilayers for multidimensional solid-state NMR experiments. In this work, we describe experimental aspects of the natural abundance 13C and 14N NMR spectroscopy of DMPC/DHPC bicelles. In particular, approaches to enhance the sensitivity and resolution and to quantify radio-frequency heating effects are presented. Sensitivity of 13C detection using single pulse excitation, conventional cross-polarization (CP), ramp-CP, and NOE techniques are compared. Our results suggest that the proton decoupling efficiency of the FLOPSY pulse sequence is better than that of continuous wave decoupling, TPPM, SPINAL, and WALTZ sequences. A simple method of monitoring the water proton chemical shift is demonstrated for the measurement of sample temperature and calibration of the radio-frequency-induced heating in the sample. The possibility of using 14N experiments on bicelles is also discussed.

  12. Optimization of sample preparation for accurate results in quantitative NMR spectroscopy

    Science.gov (United States)

    Yamazaki, Taichi; Nakamura, Satoe; Saito, Takeshi

    2017-04-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy has received high marks as an excellent measurement tool that does not require the same reference standard as the analyte. Measurement parameters have been discussed in detail and high-resolution balances have been used for sample preparation. However, the high-resolution balances, such as an ultra-microbalance, are not general-purpose analytical tools and many analysts may find those balances difficult to use, thereby hindering accurate sample preparation for qNMR measurement. In this study, we examined the relationship between the resolution of the balance and the amount of sample weighed during sample preparation. We were able to confirm the accuracy of the assay results for samples weighed on a high-resolution balance, such as the ultra-microbalance. Furthermore, when an appropriate tare and amount of sample was weighed on a given balance, accurate assay results were obtained with another high-resolution balance. Although this is a fundamental result, it offers important evidence that would enhance the versatility of the qNMR method.

  13. Rapid etiological classification of meningitis by NMR spectroscopy based on metabolite profiles and host response.

    Directory of Open Access Journals (Sweden)

    Uwe Himmelreich

    Full Text Available Bacterial meningitis is an acute disease with high mortality that is reduced by early treatment. Identification of the causative microorganism by culture is sensitive but slow. Large volumes of cerebrospinal fluid (CSF are required to maximise sensitivity and establish a provisional diagnosis. We have utilised nuclear magnetic resonance (NMR spectroscopy to rapidly characterise the biochemical profile of CSF from normal rats and animals with pneumococcal or cryptococcal meningitis. Use of a miniaturised capillary NMR system overcame limitations caused by small CSF volumes and low metabolite concentrations. The analysis of the complex NMR spectroscopic data by a supervised statistical classification strategy included major, minor and unidentified metabolites. Reproducible spectral profiles were generated within less than three minutes, and revealed differences in the relative amounts of glucose, lactate, citrate, amino acid residues, acetate and polyols in the three groups. Contributions from microbial metabolism and inflammatory cells were evident. The computerised statistical classification strategy is based on both major metabolites and minor, partially unidentified metabolites. This data analysis proved highly specific for diagnosis (100% specificity in the final validation set, provided those with visible blood contamination were excluded from analysis; 6-8% of samples were classified as indeterminate. This proof of principle study suggests that a rapid etiologic diagnosis of meningitis is possible without prior culture. The method can be fully automated and avoids delays due to processing and selective identification of specific pathogens that are inherent in DNA-based techniques.

  14. Biological effects and physical safety aspects of NMR imaging and in vivo spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tenforde, T.S.; Budinger, T.F.

    1985-08-01

    An assessment is made of the biological effects and physical hazards of static and time-varying fields associated with the NMR devices that are being used for clinical imaging and in vivo spectroscopy. A summary is given of the current state of knowledge concerning the mechanisms of interaction and the bioeffects of these fields. Additional topics that are discussed include: (1) physical effects on pacemakers and metallic implants such as aneurysm clips, (2) human health studies related to the effects of exposure to nonionizing electromagnetic radiation, and (3) extant guidelines for limiting exposure of patients and medical personnel to the fields produced by NMR devices. On the basis of information available at the present time, it is concluded that the fields associated with the current generation of NMR devices do not pose a significant health risk in themselves. However, rigorous guidelines must be followed to avoid the physical interaction of these fields with metallic implants and medical electronic devices. 476 refs., 5 figs., 2 tabs.

  15. Probing platinum azido complexes by 14N and 15N NMR spectroscopy.

    Science.gov (United States)

    Farrer, Nicola J; Gierth, Peter; Sadler, Peter J

    2011-10-17

    Metal azido complexes are of general interest due to their high energetic properties, and platinum azido complexes in particular because of their potential as photoactivatable anticancer prodrugs. However, azido ligands are difficult to probe by NMR spectroscopy due to the quadrupolar nature of (14)N and the lack of scalar (1)H coupling to enhance the sensitivity of the less abundant (15)N by using polarisation transfer. In this work, we report (14)N and (15)N NMR spectroscopic studies of cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))] (1) and trans,trans,trans-[Pt(N(3))(2)(OH)(2)(X)(Y)], where X=Y=NH(3) (2); X=NH(3), Y=py (3) (py=pyridine); X=Y=py (4); and selected Pt(II) precursors. These studies provide the first (15)N NMR data for azido groups in coordination complexes. We discuss one- and three-bond J((15)N,(195)Pt) couplings for azido and am(m)ine ligands. The (14)N(α) (coordinated azido nitrogen) signal in the Pt(IV) azido complexes is extremely broad (W(1/2)≈2124 Hz for 4) in comparison to other metal azido complexes, attributable to a highly asymmetrical electric field gradient at the (14)N(α) atom. Through the use of anti-ringing pulse sequences, the (14)N NMR spectra, which show resolution of the broad (14)N(α) peak, were obtained rapidly (e.g., 1.5 h for 10 mM 4). The linewidths of the (14)N(α) signals correlate with the viscosity of the solvent. For (15) N-enriched samples, it is possible to detect azido (15)N resonances directly, which will allow photoreactions to be followed by 1D (15)N NMR spectroscopy. The T(1) relaxation times for 3 and 4 were in the range 5.7-120 s for (15)N, and 0.9-11.3 ms for (14)N. Analysis of the (1)J((15)N,(195)Pt) coupling constants suggests that an azido ligand has a moderately strong trans influence in octahedral Pt(IV) complexes, within the series 2-picIV)-NH(3) bond to a greater extent than an axial OH(-) ligand. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. How Ions Arrange in Solution: Detailed Insight from NMR Spectroscopy of Paramagnetic Ion Pairs.

    Science.gov (United States)

    Damjanović, Marko; Morita, Takaumi; Horii, Yoji; Katoh, Keiichi; Yamashita, Masahiro; Enders, Markus

    2016-11-04

    Ion pairing between the paramagnetic anion [Tb(obPc)2 ](-) (obPc=2,3,9,10,16,17,23,24-octabutoxyphthalocyaninato), which has a very large magnetic anisotropy, with various diamagnetic counterions [P(Ph)4 ](+) (1 a), [As(Ph)4 ](+) (1 b), bis(triphenylphosphine)iminium ([PPN](+) , 1 c) and tetra-n-butylammonium ([TBA](+) , 1 d) was studied by means of (1) H, (13) C, (14) N, and (31) P NMR spectroscopy in solution at various temperatures. The influence of the paramagnetic anion on the NMR spectroscopy properties of the diamagnetic cations allowed a detailed insight into the distances and relative orientations of the paired ions. Isotropic tumbling models for the description of the quaternary cations are inaccurate, particularly for [TBA](+) with its flexible butyl chains. The effects of temperature and concentration were also assessed. The advantage of this technique is that relatively large distances and the orientation between molecules or ions in solution can be studied. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Solid state NMR studies of gels derived from low molecular mass gelators.

    Science.gov (United States)

    Nonappa; Kolehmainen, E

    2016-07-13

    Since its invention more than six decades ago, nuclear magnetic resonance (NMR) spectroscopy has evolved as an inevitable part of chemical as well as structural analysis of small molecules, polymers, biomaterials and hybrid materials. In the solution state, due to the increased viscosity of complex viscoelastic fluids such as gels, liquid crystals and other soft materials, the rate of molecular tumbling is reduced, which in turn affects the chemical shift anisotropy, dipolar and quadrupolar interactions. As a consequence the solution state NMR spectra show broad lines, and therefore, extracting detailed structural information is a challenging task. In this context, solid state (SS) NMR has the ability to distinguish between a minute amount of polymorphic forms, conformational changes, and the number of non-equivalent molecules in an asymmetric unit of a crystal lattice, and to provide both qualitative as well as quantitative analytical data with a short-range order. Therefore, SS NMR has continued to evolve as an indispensable tool for structural analysis and gave birth to a new field called NMR crystallography. Solid state cross polarization (CP) and high resolution (HR) magic angle spinning (MAS) NMR spectroscopy has been used to study weak interactions in polymer gels. However, the application of SS NMR spectroscopy to study gels derived from low molecular weight gelators has been limited until recently. In this review, we will focus on the importance of solid state NMR spectroscopy in understanding and elucidating the structure of supramolecular gels derived from low molecular weight gelators with selected examples.

  18. Solid state NMR studies of gels derived from low molecular mass gelators

    Science.gov (United States)

    Kolehmainen, E.

    2016-01-01

    Since its invention more than six decades ago, nuclear magnetic resonance (NMR) spectroscopy has evolved as an inevitable part of chemical as well as structural analysis of small molecules, polymers, biomaterials and hybrid materials. In the solution state, due to the increased viscosity of complex viscoelastic fluids such as gels, liquid crystals and other soft materials, the rate of molecular tumbling is reduced, which in turn affects the chemical shift anisotropy, dipolar and quadrupolar interactions. As a consequence the solution state NMR spectra show broad lines, and therefore, extracting detailed structural information is a challenging task. In this context, solid state (SS) NMR has the ability to distinguish between a minute amount of polymorphic forms, conformational changes, and the number of non-equivalent molecules in an asymmetric unit of a crystal lattice, and to provide both qualitative as well as quantitative analytical data with a short-range order. Therefore, SS NMR has continued to evolve as an indispensable tool for structural analysis and gave birth to a new field called NMR crystallography. Solid state cross polarization (CP) and high resolution (HR) magic angle spinning (MAS) NMR spectroscopy has been used to study weak interactions in polymer gels. However, the application of SS NMR spectroscopy to study gels derived from low molecular weight gelators has been limited until recently. In this review, we will focus on the importance of solid state NMR spectroscopy in understanding and elucidating the structure of supramolecular gels derived from low molecular weight gelators with selected examples. PMID:27374054

  19. Study of 3,3' vs. 4,4' DDS isomer curatives on physical properties and phenyl ring motions of DGEBA epoxy via molecular dynamics, deuterium NMR, and dielectric spectroscopy

    Science.gov (United States)

    Tucker, Samuel James

    The purpose of this research is to develop a multiscale understanding of crosslinked amorphous matrices, connecting molecular level events to macroscopic properties. To accomplish this goal, our methodology was to identify network architectures that influence molecular level energy dissipation through mechanisms such as bond rotations, torsions, and ring flips and then relate those molecular motions to macroscopic properties. Studies were accomplished on two aerospace grade matrices: the epoxy, diglycidyl ether of bisphenol A (DGEBA) cured with two amines, 3,3'-diaminodiphenyl sulfone (33DDS) and 4,4'-diaminodiphenyl sulfone (44DDS). The 33DDS/DGEBA and 44DDS/DGEBA served both to provide a baseline for experimental testing of aerospace matrices and to enable the comparison of a meta-substituted vs. para-substituted diamine in chemically isotropic systems. The results presented in the first seven chapters of the dissertation focus on these two matrices. Molecular Dynamics (MD) simulations provide a tool to quickly create networks with alterations in network architectures, such as crosslink density, aromaticity, sulfone content, pendant bulky groups, etc. MD can then be used to predict thermomechanical properties of these matrices and determine the effect of network architecture on properties. In this work, molecular dynamics simulations were used to accurately predict thermomechanical properties of 33DDS/DGEBA and 44DDS/DGEBA. Additionally, modifications to these baseline matrices were made in order to study the effect of network architecture and chemical composition of matrices. To bridge the gap in understanding between network architecture and ultimate matrix performance, molecular motions resulting from the network architecture and responsible for ultimate properties, must be understood. To analyze these molecular motions, various solid state Nuclear Magnetic Resonance (NMR) spectroscopic techniques, Dielectric Spectroscopy (DES), and Dynamic Mechanical Analysis

  20. Toward contrast-enhanced, optically-detected NMR spectroscopy

    Science.gov (United States)

    Meriles, Carlos; Pagliero, Daniela

    2011-03-01

    Optical detection of Nuclear Magnetic Resonance (NMR) takes place via a two-step process that relies on the interaction between optical photons and electrons on the one hand, and the hyperfine coupling between electrons and nuclear spins on the other. The latter depends on the material system under consideration while the former is dominated by the difference between the illumination and optical transition wavelengths. Here we use optical Faraday rotation to monitor nuclear spins in real time after resonant radio-frequency excitation at high-magnetic field. Comparison between inductively and optically detected NMR spectra in model sample fluids indicates that each of these mechanisms can lead to alternate forms of spectral contrast. Extension of these findings may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins, or the characterization of molecular orbitals in diamagnetic systems. We acknowledge support from the National Science Foundation.

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

    Science.gov (United States)

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

    2012-09-07

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

  2. Study of the lithiated phenylacetonitrile monoanions and dianions formed according to the lithiated base used (LHMDS, LDA, or n-BuLi). 2. Alkylation and deuteriation mechanism study by vibrational and NMR spectroscopy and quantum chemistry calculations.

    Science.gov (United States)

    Strzalko, Tekla; Wartski, Lya; Corset, Jacques; Castellà-Ventura, Martine; Froment, Françoise

    2012-08-01

    Mechanisms of alkylation by PhCH(2)Cl or CH(3)I in THF and of deuteriation by DCl (4 N in D(2)O) in THF or THF-toluene of lithiated phenylacetonitrile monoanions and dianions obtained with LHMDS, LDA, or n-BuLi are studied by vibrational and NMR spectroscopy and quantum chemistry calculations. Dialkylation of the three dilithio dianions generated with n-BuLi (2.0-2.7 equiv, THF-hexane) depends on their structure: N-lithio (PhCCNLi)(-)Li(+) and (C,N)-dilithio PhCLiCNLi dianions afford PhCR(2)CN (R = PhCH(2), CH(3)) from the intermediate N-lithio monoalkylated monoanion PhCRCNLi 10; C-lithio dianion (PhCLiCN)(-)Li(+) leads to a carbenoid species, the C-lithio monoalkylated nitrile PhCLiRCN 11, which either eliminates carbene Ph-C-R and different LiCN species or isomerizes to PhCRCNLi in the presence of LiX (X = Cl, I). Dialkylation or dideuteriation of monoanions (monomers, dimers, and heterodimers [PhCHCNLi·LiR'], R' = (SiMe(3))(2)N, (i-Pr)(2)N) obtained with LHMDS or LDA (2.4 equiv, THF) proceeds via a sequential mechanism involving monometalation-monoalkylation (or monodeuteriation) reactions. Some carbene and (LiCNLi)(+) are also observed, and explained by another mechanism implying the C-lithio monoalkylated monoanion PhCLiRCN 9 in the presence of LiX. These results show the ambiphilic behavior of PhCLiRCN as a carbenoid (11) or a carbanion (9) and the importance of LiX formed in situ in the first alkylation step.

  3. NMR spectroscopy of single sub-nL ova with inductive ultra-compact single-chip probes

    Science.gov (United States)

    Grisi, Marco; Vincent, Franck; Volpe, Beatrice; Guidetti, Roberto; Harris, Nicola; Beck, Armin; Boero, Giovanni

    2017-03-01

    Nuclear magnetic resonance (NMR) spectroscopy enables non-invasive chemical studies of intact living matter. However, the use of NMR at the volume scale typical of microorganisms is hindered by sensitivity limitations, and experiments on single intact organisms have so far been limited to entities having volumes larger than 5 nL. Here we show NMR spectroscopy experiments conducted on single intact ova of 0.1 and 0.5 nL (i.e. 10 to 50 times smaller than previously achieved), thereby reaching the relevant volume scale where life development begins for a broad variety of organisms, humans included. Performing experiments with inductive ultra-compact (1 mm2) single-chip NMR probes, consisting of a low noise transceiver and a multilayer 150 μm planar microcoil, we demonstrate that the achieved limit of detection (about 5 pmol of 1H nuclei) is sufficient to detect endogenous compounds. Our findings suggest that single-chip probes are promising candidates to enable NMR-based study and selection of microscopic entities at biologically relevant volume scales.

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

    African Journals Online (AJOL)

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

  5. Evidence for cross-linking in tomato cutin using HR-MAS NMR spectroscopy.

    Science.gov (United States)

    Deshmukh, Ashish P; Simpson, André J; Hatcher, Patrick G

    2003-11-01

    Cutin is a polyester biopolymer component of plant leaf and fruit cuticles, most often associated with waxes and cuticular polysaccharides, and sometimes with another aliphatic biopolymer called cutan. Insolubility of these cuticular biopolymers has made it difficult to apply traditional analytical techniques for structure determination, because most techniques providing molecular level details require solubility. By using the relatively new technique of one and two-dimensional high-resolution magic angle spinning (HR-MAS) NMR spectroscopy, with added information from solid-state 13C NMR spectroscopy, detailed through-bond connectivities and assignments are made for cutin from Lycopersicon esculentum (tomato) fruit. Based on the data obtained, tomato cutin is found to be predominantly an aliphatic polyester with some olefinic and aromatic moieties, consistent with previous studies that employed various degradative approaches. Aside from esters, there are free primary and secondary alcohol groups, as well as free fatty acids. A significant finding is the presence of alpha-branched fatty acids/esters. Mid-chain hydroxyls appear to be generally unesterified, but esters of mid-chain hydroxyls have been identified. The alpha-branched fatty acids/esters and esters of mid-chain hydroxyls could point towards cross-linking.

  6. Phosphorus Speciation of Sequential Extracts of Organic Amendments using NMR Spectroscopy

    Science.gov (United States)

    Akinremi, O.

    2009-04-01

    O.O. 1Akinremi Babasola Ajiboye and Donald N. Flaten 1Department of Soil Science, University of Manitoba, Winnipeg, R3T 2NT, Canada We carried out this study in order to determine the forms of phosphorus in various organic amendments using state-of-the art spectroscopic technique. Anaerobically digested biosolids (BIO), hog (HOG), dairy (DAIRY), beef (BEEF) and poultry (POULTRY) manures were subjected to sequential extraction. The extracts were analyzed by solution 31P nuclear magnetic resonance (NMR) spectroscopy. Most of the total P analysed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) in the sequential extracts of organic amendments were orthophosphate, except POULTRY, which was dominated by organic P. The labile P fraction in all the organic amendments, excluding POULTRY, was mainly orthophosphate P from readily soluble calcium and some aluminum phosphates. In the poultry litter, however, Ca phytate was the main P species controlling P solubility. Such knowledge of the differences in the chemical forms of phosphorus in organic amendments are essential for proper management of these amendments for agro-environmental purposes Key words: organic amendments, solution NMR, sequential fractionation, labile phosphorus

  7. 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

    2017-06-06

    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 310-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.

  8. Profiling formulated monoclonal antibodies by (1)H NMR spectroscopy.

    Science.gov (United States)

    Poppe, Leszek; Jordan, John B; Lawson, Ken; Jerums, Matthew; Apostol, Izydor; Schnier, Paul D

    2013-10-15

    Nuclear magnetic resonance (NMR) is arguably the most direct methodology for characterizing the higher-order structure of proteins in solution. Structural characterization of proteins by NMR typically utilizes heteronuclear experiments. However, for formulated monoclonal antibody (mAb) therapeutics, the use of these approaches is not currently tenable due to the requirements of isotope labeling, the large size of the proteins, and the restraints imposed by various formulations. Here, we present a new strategy to characterize formulated mAbs using (1)H NMR. This method, based on the pulsed field gradient stimulated echo (PGSTE) experiment, facilitates the use of (1)H NMR to generate highly resolved spectra of intact mAbs in their formulation buffers. This method of data acquisition, along with postacquisition signal processing, allows the generation of structural and hydrodynamic profiles of antibodies. We demonstrate how variation of the PGSTE pulse sequence parameters allows proton relaxation rates and relative diffusion coefficients to be obtained in a simple fashion. This new methodology can be used as a robust way to compare and characterize mAb therapeutics.

  9. Probing site-specific 13C/15N-isotope enrichment of spider silk with liquid-state NMR spectroscopy.

    Science.gov (United States)

    Shi, Xiangyan; Yarger, Jeffery L; Holland, Gregory P

    2013-05-01

    Solid-state nuclear magnetic resonance (NMR) has been extensively used to elucidate spider silk protein structure and dynamics. In many of these studies, site-specific isotope enrichment is critical for designing particular NMR methods for silk structure determination. The commonly used isotope analysis techniques, isotope-ratio mass spectroscopy and liquid/gas chromatography-mass spectroscopy, are typically not capable of providing the site-specific isotope information for many systems because an appropriate sample derivatization method is not available. In contrast, NMR does not require any sample derivatization or separation prior to analysis. In this article, conventional liquid-state (1)H NMR was implemented to evaluate incorporation of (13)C/(15)N-labeled amino acids in hydrolyzed spider dragline silk. To determine site-specific (13)C and (15)N isotope enrichments, an analysis method was developed to fit the (1)H-(13)C and (1)H-(15)N J-splitting (J CH and J NH) (1)H NMR peak patterns of hydrolyzed silk fiber. This is demonstrated for Nephila clavipes spiders, where [U-(13)C3,(15)N]-Ala and [1-(13)C,(15)N]-Gly were dissolved in their water supplies. Overall, contents for Ala and Gly isotopomers are extracted for these silk samples. The current methodology can be applied to many fields where site-specific tracking of isotopes is of interest.

  10. NMR studies on UPt 3

    Science.gov (United States)

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

    2000-06-01

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

  11. Studies of Transition Metal Complexes Using Dynamic NMR Techniques.

    Science.gov (United States)

    Coston, Timothy Peter John

    Available from UMI in association with The British Library. This Thesis is primarily concerned with the quantitative study of fluxional processes in, predominantly platinum(IV) complexes, with the ligands 1,1,2,2-tetrakis(methylthio)ethane (MeS)_2CHCH(SMe)_2 , and 1,1,2,2-tetrakis(methylthio)ethene (MeS) _2C=C(SMe)_2. Quantitative information relating to the energetics of these processes has been obtained by a combination of one- and two-dimensional NMR techniques. Chapter One provides an introduction to the background of fluxional processes in transition metal complexes together with data concerning the energetics of the processes that have already been studied by NMR techniques. Chapter Two provides a thorough grounding in NMR techniques, in particular those concerned with the quantitative measurement of rates involved in chemical exchange processes. A description of the use of 2D EXSY NMR spectroscopy in obtaining rate data is given. The properties of the magnetic isotope of platinum are given in Chapter Three. A general survey is also given of some additional compounds that have already been studied by platinum-195 spectroscopy. Chapter Four is concerned with the quantitative study of low temperature (complexes (PtXMe_3 (MeS)_2CHCH(SMe) _2) (X = Cl, Br, I). These complexes were studied by dynamic nuclear magnetic resonance and the information regarding the rates of sulphur inversion was obtained by complete band-shape analysis. Chapter Five is concerned with high temperature (>333 K) fluxionality, of the previous complexes, as studied by a combination of one- and two -dimensional NMR techniques. Aside from obtaining thermodynamic parameters for all the processes, a new novel mechanism is proposed. Chapter Six is primarily concerned with the NMR investigation of the new dinuclear complexes ((PtXMe _3)_2(MeS) _2CHCH(SMe)_2) (X = Cl, Br, I). The solution properties have been established and thermo-dynamic parameters obtained for low and high temperature

  12. Comparison of the compression strength of human vertebral bodies with the mass and density of apatite: a study by 31P NMR spectroscopy.

    Science.gov (United States)

    Brown, C E; Srinivasan, R; Sigmann, P; Myklebust, J B; Battocletti, J H

    1988-10-01

    The force needed to fracture individual human thoracic and lumbar vertebral bodies is compared with the mass and density of apatite. 31P NMR spectrometry was used to quantify the apatite, because it permits the mineral content of bone to be determined noninvasively with minimal nonspecific interference from the organic matrix or from variations in composition of the marrow. Experiments were performed with bones of similar structure and function from a single individual with no history of trabecular fractures, to compensate for the effects of the other variables that affect bone strength. The coefficient of correlation between compression strength and the volume density (i.e., g/cm3) of apatite was 0.95. The correlation of strength with the mass (i.e., grams) of apatite in a vertebral body also was reasonably good, r = 0.82, but correlations with areal density (i.e., g/cm2) and linear density (i.e., g/cm) were much poorer.

  13. NMR structural studies on antifreeze proteins.

    Science.gov (United States)

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

    1998-01-01

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

  14. Gradient-Diffusion Methods for Simulating Decoherence by NMR Spectroscopy

    CERN Document Server

    Havel, T F; Viola, L; Cory, D G; Havel, Timothy F.; Sharf, Yehuda; Viola, Lorenza; Cory, David G.

    2001-01-01

    Theoretical techniques are developed for designing nuclear magnetic resonance (NMR) experiments to simulate a variety of adiabatic decoherence (aka T_2 relaxation) processes, using sequences of pulsed field gradients and diffusion periods. To this end an efficient Hadamard product formalism is introduced and used to derive Lindblad master equations from NMR pulse sequences for both collective and independent phase damping on any number of spins. The Kraus operator sum form is shown to be related to the Hadamard form by diagonalization, and explicit Lindblad and Kraus operators given for arbitrary correlations between two spins. Finally, gradient-diffusion methods are outlined for more complex forms of decoherence, including the three-axis collective model.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    DEFF Research Database (Denmark)

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

    1994-01-01

    . A nonmagnetic ergometer was used for ankle dorsiflexions that activated only the anterior tibial muscle as verified by post exercise imaging. The coil design and the adiabatic sech/tanh pulse improved sensitivity by 45% and 56% respectively, compared with standard techniques. Simultaneous electromyographic......The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human...... skeletal muscle, a relationship that is still poorly understood. This study describes the optimization of skeletal muscle 31P-MRS in a whole-body magnet, involving surface coil design, utilization of adiabatic radio frequency pulses and advanced time-domain fitting, to the technical design of SEMG...

  18. 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.

  19. The host plant Pinus pinaster exerts specific effects on phosphate efflux and polyphosphate metabolism of the ectomycorrhizal fungus Hebeloma cylindrosporum: a radiotracer, cytological staining and (31) P NMR spectroscopy study.

    Science.gov (United States)

    Torres-Aquino, Margarita; Becquer, Adeline; Le Guernevé, Christine; Louche, Julien; Amenc, Laurie K; Staunton, Siobhan; Quiquampoix, Hervé; Plassard, Claude

    2017-02-01

    Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP) synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypothesis for the ECM fungus Hebeloma cylindrosporum grown in vitro and incubated without plant or with host (Pinus pinaster) and non-host (Zea mays) plants, using an experimental system simulating the symbiotic interface. We used (32) P labelling to quantify P accumulation and P efflux and in vivo and in vitro nuclear magnetic resonance (NMR) spectroscopy and cytological staining to follow the fate of fungal polyP. Phosphate supply triggered a massive P accumulation as newly synthesized long-chain polyP in H. cylindrosporum if previously grown under P-deficient conditions. P efflux from H. cylindrosporum towards the roots was stimulated by both host and non-host plants. However, the host plant enhanced (32) P release compared with the non-host plant and specifically increased the proportion of short-chain polyP in the interacting mycelia. These results support the existence of specific host plant effects on fungal P metabolism able to provide P in the apoplast of ectomycorrhizal roots.

  20. Metal Carbonation of Forsterite in Wet Supercritical CO2: The Role of H2O Studied by Solid State C-13 and Si-29 NMR Spectroscopy

    Science.gov (United States)

    Hu, J.; Kwak, J.; Turcu, R. V.; Rosso, K. M.; Ilton, E. S.; Wang, C.; Sears, J. A.; Felmy, A. R.; Hoyt, D. W.

    2010-12-01

    Selected as a model mineral carbonation system for geological carbon sequestration in mafic host rocks, chemical mechanisms of forsterite carbonation in supercritical CO2 containing water varied from dry to well above saturation, including at saturation, were investigated by a combination of solid state NMR (C-13 SP-, CP-MAS, Si-29 SP-, CP-MAS), XRD, TEM and XPS. Run conditions were 80 degrees (C) and 75 bars. Major findings are as follows. At high water contents where a bulk aqueous solution coexisted with water-saturated scCO2, forsterite was converted into magnesite and a separate Mg-free amorphous SiO2 reaction product characterized by highly polymerized oligomeric Q4, and to a lesser extent by Q3 silica species. As the amount of added water was reduced, hydrated intermediate reaction products that did not evolve to magnesite could be identified until at zero water no reaction intermediates or magnesite carbonation products were observed. The intermediate reaction products identified were a complex mixture of partially hydrated/hydroxylated magnesium carbonate species and a variety of surface silica species with low polymerization extent. The intermediates were mainly in an amorphous state, forming a thin layer on the surface. Formation of these intermediate species consumes water by hydrolysis of Mg-O-Si linkages at the forsterite surface as well as by incorporation of water in the lattice. If insufficient water is available, the reaction is found not to proceed far enough to form magnesite and amorphous SiO2. Water in excess of this limit appears necessary for the intermediates to evolve to anhydrous magnesite, a process that is expected to liberate water for continued reaction. Hence, for a given fluid/forsterite ratio there appears to be a water threshold (i.e., the formation of H2O film with sufficient thickness estimated to be between 3.2 and 18.4 nm) above which a significant portion of the water is recycled in an apparent quasi-catalytic role for the

  1. Enhanced detection of aldehydes in Extra-Virgin Olive Oil by means of band selective NMR spectroscopy

    Science.gov (United States)

    Dugo, Giacomo; Rotondo, Archimede; Mallamace, Domenico; Cicero, Nicola; Salvo, Andrea; Rotondo, Enrico; Corsaro, Carmelo

    2015-02-01

    High resolution Nuclear Magnetic Resonance (NMR) spectroscopy is a very powerful tool for comprehensive food analyses and especially for Extra-Virgin Olive Oils (EVOOs). We use the NMR technique to study the spectral region of aldehydes (8-10 ppm) for EVOOs coming from the south part of Italy. We perform novel experiments by using mono and bidimensional band selective spin-echo pulse sequences and identify four structural classes of aldehydes in EVOOs. For the first time such species are identified in EVOOs without any chemical treatment; only dilution with CDCl3 is employed. This would allow the discrimination of different EVOOs for the aldehydes content increasing the potentiality of the NMR technique in the screening of metabolites for geographical characterization of EVOOs.

  2. Complex mixture analysis of organic compounds in green coffee bean extract by two-dimensional NMR spectroscopy.

    Science.gov (United States)

    Wei, Feifei; Furihata, Kazuo; Hu, Fangyu; Miyakawa, Takuya; Tanokura, Masaru

    2010-11-01

    A complex mixture analysis by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy was carried out for the first time for the identification and quantification of organic compounds in green coffee bean extract (GCBE). A combination of (1)H-(1)H DQF-COSY, (1)H-(13)C HSQC, and (1)H-(13)C CT-HMBC two-dimensional sequences was used, and 16 compounds were identified. In particular, three isomers of caffeoylquinic acid were identified in the complex mixture without any separation. In addition, GCBE components were quantified by the integration of carbon signals by use of a relaxation reagent and an inverse-gated decoupling method without a nuclear Overhauser effect. This NMR methodology provides detailed information about the kinds and amounts of GCBE components, and in our study, the chemical makeup of GCBE was clarified by the NMR results. 2010 John Wiley & Sons, Ltd.

  3. Using relaxation dispersion NMR spectroscopy to determine structures of excited, invisible protein states

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, D. Flemming; Vallurupalli, Pramodh; Kay, Lewis E. [University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)], E-mail: kay@pound.med.utoronto.ca

    2008-07-15

    Currently the main focus of structural biology is the determination of static three-dimensional representations of biomolecules that for the most part correspond to low energy (ground state) conformations. However, it is becoming increasingly well recognized that higher energy structures often play important roles in function as well. Because these conformers are populated to only low levels and are often only transiently formed their study is not amenable to many of the tools of structural biology. In this perspective we discuss the role of CPMG-based relaxation dispersion NMR spectroscopy in characterizing these low populated, invisible states. It is shown that robust methods for measuring both backbone chemical shifts and residual anisotropic interactions in the excited state are in place and that these data provide valuable restraints for structural studies of invisible conformers.

  4. NMR spectroscopy of aminoacylase 1 deficiency, a novel inborn error of metabolism.

    Science.gov (United States)

    Engelke, Udo F H; Sass, Jörn Oliver; Van Coster, Rudy N; Gerlo, Erik; Olbrich, Heike; Krywawych, Stefan; Calvin, Jacqui; Hart, Claire; Omran, Heymut; Wevers, Ron A

    2008-02-01

    Aminoacylase 1 deficiency is a novel inborn error of metabolism. The clinical significance of the deficiency is under discussion, as well as the possible consequences of the defect for brain metabolism and function. This study includes the five originally published cases as well as three novel ones. NMR spectroscopy of urine, serum and cerebrospinal fluid has been used to study these patients. A typical profile with 11 accumulating N-acetylated amino acids was observed in urine from the patients. The concentration of most of the accumulating metabolites is typically 100-500 micromol/mmol creatinine. Two additional minor N-acetylated metabolites remain unidentified. The concentrations of the accumulating metabolites are amino acids in the cerebrospinal fluid from one patient. Our data define aminoacylase 1 deficiency at the metabolite level providing a specific urinary profile of accumulating N-acetylated amino acids.

  5. Probing the interaction of U(vi) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy.

    Science.gov (United States)

    Uribe, Eva C; Mason, Harris E; Shusterman, Jennifer A; Bruchet, Anthony; Nitsche, Heino

    2016-06-21

    The fundamental interaction of U(vi) with diethylphosphatoethyl triethoxysilane functionalized SBA-15 mesoporous silica is studied by macroscopic batch experiments and solid-state NMR spectroscopy. DPTS-functionalized silica has been shown to extract U(vi) from nitric acid solutions at or above pH 3. Extraction is dependent on pH and ionic strength. Single-pulse (31)P NMR on U(vi) contacted samples revealed that U(vi) only interacts with a fraction of the ligands present on the surface. At pH 4 the U(vi) extraction capacity of the material is limited to 27-37% of the theoretical capacity, based on ligand loading. We combined single pulse (31)P NMR on U(vi)-contacted samples with batch studies to measure a ligand-to-metal ratio of approximately 2 : 1 at pH 3 and 4. Batch studies and cross-polarization NMR measurements reveal that U(vi) binds to deprotonated phosphonate and/or silanol sites. We use (31)P-(31)P DQ-DRENAR NMR studies to compare the average dipolar coupling between phosphorus spins for both U(vi)-complexed and non-complexed ligand environments. These measurements reveal that U(vi) extraction is not limited by inadequate surface distribution of ligands, but rather by low stability of the surface phosphonate complex.

  6. Studies on supramolecular gel formation using DOSY NMR.

    Science.gov (United States)

    Nonappa; Šaman, David; Kolehmainen, Erkki

    2015-04-01

    Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential DOSY processing, and the results were compared with the automated Bayesian DOSY transformation to obtain 2D plots. Our results provide useful information on the stepwise self-assembly of small molecules leading to gelation. We believe that the results obtained from these experiments are applicable in determining the CGC and gel melting temperatures of supramolecular gels.

  7. Theory of mirrored time domain sampling for NMR spectroscopy.

    Science.gov (United States)

    Ghosh, Arindam; Wu, Yibing; He, Yunfen; Szyperski, Thomas

    2011-12-01

    A generalized theory is presented for novel mirrored hypercomplex time domain sampling (MHS) of NMR spectra. It is the salient new feature of MHS that two interferograms are acquired with different directionality of time evolution, that is, one is sampled forward from time t=0 to the maximal evolution time tmax, while the second is sampled backward from t=0 to -tmax. The sampling can be accomplished in a (semi) constant time or non constant-time manner. Subsequently, the two interferograms are linearly combined to yield a complex time domain signal. The manifold of MHS schemes considered here is defined by arbitrary settings of sampling phases ('primary phase shifts') and amplitudes of the two interferograms. It is shown that, for any two given primary phase shifts, the addition theorems of trigonometric functions yield the unique linear combination required to form the complex signal. In the framework of clean absorption mode (CAM) acquisition of NMR spectra being devoid of residual dispersive signal components, 'secondary phase shifts' represent time domain phase errors which are to be eliminated. In contrast, such secondary phase shifts may be introduced by experimental design in order to encode additional NMR parameters, a new class of NMR experiments proposed here. For generalization, it is further considered that secondary phase shifts may depend on primary phase shifts and/or sampling directionality. In order to compare with MHS theory, a correspondingly generalized theory is derived for widely used hypercomplex ('States') sampling (HS). With generalized theory it is shown, first, that previously introduced 'canonical' schemes, characterized by primary phases being multiples of π/4, afford maximal intensity of the desired absorptive signals in the absence of secondary phase shifts, and second, how primary phases can be adjusted to maximize the signal intensity provided that the secondary phase shifts are known. Third, it is demonstrated that theory enables

  8. MODERN NMR TECHNIQUES FOR THE STUDY OF LARGE PROTEINS IN SOLUTION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A number of important methodological developments in high resolution NMR spectroscopy have led to significant increases in the size limitations that previously impeded solution structural studies of macromolecules. Specifically, isotope labeling and TROSY triple resonance spectroscopy has resulted in substantial sensitivity and resolution gain for applications to large molecular weight proteins.

  9. Application of 13C NMR spectroscopy to characterize organic chemical components of decomposing coarse woody debris from different climatic regions

    Directory of Open Access Journals (Sweden)

    Takuya Hishinuma

    2015-04-01

    Full Text Available Solid-state 13C nuclear magnetic resonance (NMR spectroscopy was applied to coarse woody debris (CWD in different stages of decomposition and collected from forest floor of a subtropical, a cool temperate, and a subalpine forest in Japan. The purpose was to test its applicability to characterize organic chemical composition of CWD of broad-leaved and coniferous trees from different climatic conditions. O-alkyl-C, mainly representing carbohydrates, was the predominant component of CWD at the three sites, accounting for 43.5-58.1% of the NMR spectra. Generally, the relative area under the signals for aromatic-C and phenolic-C, mainly representing lignin, increased, whereas the relative area for O-alkyl-C decreased, as the decay class advanced. The relative area under NMR chemical shift regions was significantly correlated with the chemical properties examined with proximate analyses. That is, O-alkyl-C and di-O-alkyl-C NMR signal areas were positively correlated with the volumetric density of CWD and the content of total carbohydrates. Methoxyl-C, aromatic-C, phenolic-C, carboxyl-C, and carbonyl-C were positively correlated with the contents of acid-unhydrolyzable residues (lignin, tannins, and cutin and nitrogen. Lignin-C calculated from NMR signals increased, and polysaccharide-C decreased, with the decay class of CWD at the three study sites. A review of previous studies on 13C NMR spectroscopy for decomposing CWD suggested further needs of its application to broad-leaved trees from tropical and subtropical regions.

  10. Ultrasensitive anion detection by NMR spectroscopy: a supramolecular strategy based on modulation of chemical exchange rate.

    Science.gov (United States)

    Perruchoud, Loïse H; Hadzovic, Alen; Zhang, Xiao-An

    2015-06-08

    NMR spectroscopy is a powerful tool for monitoring molecular interactions and is widely used to characterize supramolecular systems at the atomic level. NMR is limited for sensing purposes, however, due to low sensitivity. Dynamic processes such as conformational changes or binding events can induce drastic effects on NMR spectra in response to variations in chemical exchange (CE) rate, which can lead to new strategies in the design of supramolecular sensors through the control and monitoring of CE rate. Here, we present an indirect NMR anion sensing technique in which increased CE rate, due to anion-induced conformational flexibility of a relatively rigid structure of a novel sensor, allows ultrasensitive anion detection as low as 120 nM.

  11. NMR difference spectroscopy with a dual saddle-coil difference probe.

    Science.gov (United States)

    Macnaughtan, Megan A; Smith, Aaron P; Goldsbrough, Peter B; Santini, Robert E; Raftery, Daniel

    2004-03-01

    A new difference probe for nuclear magnetic resonance (NMR) spectroscopy is presented. The difference probe uses two saddle-shaped coils to excite and detect two samples simultaneously. The samples are held in a specially modified 3-mm NMR tube with an Ultem plastic disk to separate the samples. The probe's resonant circuit contains two crossed diodes that passively switch the relative phase of each coil during the NMR experiment. The result is a difference spectrum from the two samples. The degree of cancellation of common signals was determined to be approximately 90%, and the application of the probe to relaxation-edited difference spectroscopy for identifying protein-ligand interactions was demonstrated using glutathione and glutathione S-transferase binding protein.

  12. Identification of Imitation Cheese and Imitation Ice Cream Based on Vegetable Fat Using NMR Spectroscopy and Chemometrics

    OpenAIRE

    Monakhova, Yulia B.; Rolf Godelmann; Claudia Andlauer; Thomas Kuballa; Lachenmeier, Dirk W.

    2013-01-01

    Vegetable oils and fats may be used as cheap substitutes for milk fat to manufacture imitation cheese or imitation ice cream. In this study, 400 MHz nuclear magnetic resonance (NMR) spectroscopy of the fat fraction of the products was used in the context of food surveillance to validate the labeling of milk-based products. For sample preparation, the fat was extracted using an automated Weibull-Stoldt methodology. Using principal component analysis (PCA), imitation products can be easily dete...

  13. Predicting Fuel Ignition Quality Using 1H NMR Spectroscopy and Multiple Linear Regression

    KAUST Repository

    Abdul Jameel, Abdul Gani

    2016-09-14

    An improved model for the prediction of ignition quality of hydrocarbon fuels has been developed using 1H nuclear magnetic resonance (NMR) spectroscopy and multiple linear regression (MLR) modeling. Cetane number (CN) and derived cetane number (DCN) of 71 pure hydrocarbons and 54 hydrocarbon blends were utilized as a data set to study the relationship between ignition quality and molecular structure. CN and DCN are functional equivalents and collectively referred to as D/CN, herein. The effect of molecular weight and weight percent of structural parameters such as paraffinic CH3 groups, paraffinic CH2 groups, paraffinic CH groups, olefinic CH–CH2 groups, naphthenic CH–CH2 groups, and aromatic C–CH groups on D/CN was studied. A particular emphasis on the effect of branching (i.e., methyl substitution) on the D/CN was studied, and a new parameter denoted as the branching index (BI) was introduced to quantify this effect. A new formula was developed to calculate the BI of hydrocarbon fuels using 1H NMR spectroscopy. Multiple linear regression (MLR) modeling was used to develop an empirical relationship between D/CN and the eight structural parameters. This was then used to predict the DCN of many hydrocarbon fuels. The developed model has a high correlation coefficient (R2 = 0.97) and was validated with experimentally measured DCN of twenty-two real fuel mixtures (e.g., gasolines and diesels) and fifty-nine blends of known composition, and the predicted values matched well with the experimental data.

  14. Solid State NMR Studies of Energy Conversion and Storage Materials

    Science.gov (United States)

    Jankuru Hennadige, Sohan Roshel De Silva

    NMR (Nuclear magnetic resonance) spectroscopy is utilized to study energy conversion and storage materials. Different types of NMR techniques including Magic Angle Spinning, Cross-polarization and relaxation measurement experiments were employed. Four different projects are discussed in this dissertation. First, three types of CFx battery materials were investigated. Electrochemical studies have demonstrated different electrochemical performances by one type, delivering superior performance over the other two. 13C and 19F MAS NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among different types. Next as the second project, layered polymer dielectrics were investigated by NMR. Previous studies have shown that thin film capacitors are improved by using alternate layers of two polymers with complementary properties: one with a high breakdown strength and one with high dielectric constant as opposed to monolithic layers. 13C to 1H cross-polarization techniques were used to investigate any inter-layer properties that may cause the increase in the dielectric strength. The third project was to study two types of thermoelectric materials. These samples were made of heavily doped phosphorous and boron in silicon by two different methods: ball-milled and annealed. These samples were investigated by NMR to determine the degree of disorder and obtain insight into the doping efficiency. The last ongoing project is on a lithium-ion battery system. The nature of passivating layers or the solid electrolyte interphase (SEI) formed on the electrodes surface is important because of the direct correlation between the SEI and the battery life time/durability. Multinuclear (7Li, 19F, 31P) techniques are employed to identify the composition of the SEI formation of both positive and negative electrodes.

  15. Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory

    Science.gov (United States)

    Pavel, John T.; Hyde, Erin C.; Bruch, Martha D.

    2012-01-01

    This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possible…

  16. Stereochemical investigation of selegiline HCl with /sup 1/H and /sup 13/C NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Podanyi, B. (CHINOIN Gyogyszer- es Vegyeszeti Termekek Gyara, Budapest (Hungary))

    1982-12-01

    Selegiline HCl, the bioactive substance of the antiparkinsonic medicine, JUMEX was investigated by NMR spectroscopy. The dominant conformer was determined. Optically active shift-reagent was used for the determination of optical purity. The /sup 13/C spectrum was analyzed, and molecular dynamics was investigated at different temperatures.

  17. Introducing High School Students to NMR Spectroscopy through Percent Composition Determination Using Low-Field Spectrometers

    Science.gov (United States)

    Bonjour, Jessica L.; Pitzer, Joy M.; Frost, John A.

    2015-01-01

    Mole to gram conversions, density, and percent composition are fundamental concepts in first year chemistry at the high school or undergraduate level; however, students often find it difficult to engage with these concepts. We present a simple laboratory experiment utilizing portable nuclear magnetic resonance spectroscopy (NMR) to determine the…

  18. 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…

  19. Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory

    Science.gov (United States)

    Pavel, John T.; Hyde, Erin C.; Bruch, Martha D.

    2012-01-01

    This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possible…

  20. USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY TO INVESTIGATE PMDI REACTIONS WITH WOOD

    Science.gov (United States)

    Solution-state NMR spectroscopy provides a powerful tool for understanding the formation of chemical bonds between wood components and adhesives. Finely ground cell wall (CW) material fully dissolves in a solvent system containing dimethylsulfoxide (DMSO-d6) and N-methyl¬imidazole (NMI-d6), keeping ...

  1. 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…

  2. 1H NMR spectroscopy-based interventional metabolic phenotyping

    DEFF Research Database (Denmark)

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

    2010-01-01

    1H NMR spectroscopy-based metabolic phenotyping was used to identify biomarkers in the plasma of patients with rheumatoid arthritis (RA). Forty-seven patients with RA (23 with active disease at baseline and 24 in remission) and 51 healthy subjects were evaluated during a one-year follow-up with a...

  3. Carbon-deuterium rotational-echo double-resonance NMR spectroscopy of lyophilized aspartame formulations.

    Science.gov (United States)

    Luthra, Suman A; Utz, Marcel; Gorman, Eric M; Pikal, Michael J; Munson, Eric J; Lubach, Joseph W

    2012-01-01

    In this study, changes in the local conformation of aspartame were observed in annealed lyophilized glasses by monitoring changes in the distance between two labeled sites using C-(2)H rotational-echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. Confirmation that the REDOR experiments were producing accurate distance measurement was ensured by measuring the (13)C-(15)N distance in glycine. The experiment was further verified by measuring the REDOR dephasing curve on (13)C-(2)H methionine. (13)C-(2)H REDOR dephasing curves were then measured on lyophilized aspartame-disaccharide formulations. In aspartame-sucrose formulation, the internuclear distances increased upon annealing, which correlated with decreased chemical reactivity. By contrast, annealing had only a minimal effect on the dephasing curve in aspartame-trehalose formulation. The results show that stability is a function of both mobility and local structure (conformation), even in a small molecule system such as lyophilized aspartame-sucrose.

  4. Quantitative analysis of sesquiterpene lactones in extract of Arnica montana L. by 1H NMR spectroscopy.

    Science.gov (United States)

    Staneva, Jordanka; Denkova, Pavletta; Todorova, Milka; Evstatieva, Ljuba

    2011-01-01

    (1)H NMR spectroscopy was used as a method for quantitative analysis of sesquiterpene lactones present in a crude lactone fraction isolated from Arnica montana. Eight main components - tigloyl-, methacryloyl-, isobutyryl- and 2-methylbutyryl-esters of helenalin (H) and 11α,13-dihydrohelenalin (DH) were identified in the studied sample. The method allows the determination of the total amount of sesquiterpene lactones and the quantity of both type helenalin and 11α,13-dihydrohelenalin esters separately. Furthermore, 6-O-tigloylhelenalin (HT, 1), 6-O-methacryloylhelenalin (HM, 2), 6-O-tigloyl-11α,13-dihydrohelenalin (DHT, 5), and 6-O-methacryloyl-11α,13-dihydrohelenalin (DHM, 6) were quantified as individual components.

  5. Exploiting hydrophobicity for efficient production of transmembrane helices for structure determination by NMR spectroscopy

    DEFF Research Database (Denmark)

    Bugge, Katrine Østergaard; Steinocher, Helena; Brooks, Andrew J.

    2015-01-01

    Despite the biological and pharmaceutical significance of membrane proteins, their tertiary structures constitute less than 3% of known structures. One of the major obstacles for initiating structural studies of membrane proteins by NMR spectroscopy is the generation of high amounts of isotope......-labeled protein. In this work, we have exploited the hydrophobic nature of membrane proteins to develop a simple and efficient production scheme for isotope-labeled single-pass transmembrane domains (TMDs) with or without intrinsically disordered regions. We have evaluated the applicability and limitations...... of the strategy using seven membrane protein variants that differ in their overall hydrophobicity and length and show a recovery for suitable variants of >70%. The developed production scheme is cost-efficient and easy to implement and has the potential to facilitate an increase in the number of structures...

  6. 2H NMR studies of supercooled and glassy aspirin

    Science.gov (United States)

    Nath, R.; Nowaczyk, A.; Geil, B.; Bohmer, R.

    2007-11-01

    Acetyl salicylic acid, deuterated at the methyl group, was investigated using 2H-NMR in its supercooled and glassy states. Just above the glass transition temperature the molecular reorientations were studied using stimulated-echo spectroscopy and demonstrated a large degree of similarity with other glass formers. Deep in the glassy phase the NMR spectra look similar to those reported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they are indicative for rotational tunneling with a relatively large tunneling frequency. Measurements of the spin-lattice relaxation times for temperatures below 150 K reveal a broad distribution of correlation times in the glass. The dominant energy barrier characterizing the slow-down of the methyl group is significantly smaller than the well defined barrier in the crystal.

  7. 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.

  8. Metabolomic changes in CSF of migraine patients measured with (1)H-NMR spectroscopy.

    Science.gov (United States)

    Zielman, Ronald; Postma, Rudmer; Verhoeven, Aswin; Bakels, Floor; van Oosterhout, Willebrordus P J; Meissner, Axel; van den Maagdenberg, Arn M J M; Terwindt, Gisela M; Mayboroda, Oleg A; Ferrari, Michel D

    2016-11-15

    Migraine is a common episodic brain disorder. Treatment options and diagnosis are hampered by an incomplete understanding of disease pathophysiology and the lack of objective diagnostic markers. The aim of this study was to identify biochemical differences characteristic for different subtypes of migraine in cerebrospinal fluid (CSF) of migraine patients using an exploratory (1)H-NMR-based metabolomics approach. CSF was obtained, in between migraine attacks, via lumbar puncture from patients with hemiplegic migraine, migraine with aura, migraine without aura, and healthy controls. Metabolite concentrations were measured by quantitative (1)H-NMR spectroscopy. Multivariate data analysis was used to find the optimal set of predictors, generalized linear models (GLM) were used to ascertain the differential significance of individual metabolites. In CSF samples from 18 patients with hemiplegic migraine, 38 with migraine with aura, 27 migraine without aura, and 43 healthy controls, nineteen metabolites were identified and quantified. Hemiplegic migraine patients could be discriminated from healthy controls using supervised multivariate modelling with 2-hydroxybutyrate and 2-hydroxyisovalerate as the most discriminant metabolites. Univariate GLM analysis showed 2-hydroxybutyrate to be lower in hemiplegic migraine compared with healthy controls; no significant differences were observed for other metabolites. It was not possible to discriminate migraine with and without aura from healthy controls based on their metabolic profile. Using an exploratory (1)H-NMR metabolomics analysis we identified metabolites that were able to discriminate hemiplegic migraine patients from healthy controls. The lower levels of 2-hydroxybutyrate found in patients with hemiplegic migraine could indicate a dysregulation of the brain's energy metabolism. An experimental confirmation in vitro or in animal models will be required to confirm or discard this hypothesis. Migraine with and migraine

  9. In Situ and Ex Situ Low-Field NMR Spectroscopy and MRI Endowed by SABRE Hyperpolarization**

    Science.gov (United States)

    Barskiy, Danila A.; Kovtunov, Kirill V.; Koptyug, Igor V.; He, Ping; Groome, Kirsten A.; Best, Quinn A.; Shi, Fan; Goodson, Boyd M.; Shchepin, Roman V.; Truong, Milton L.; Coffey, Aaron M.; Waddell, Kevin W.; Chekmenev, Eduard Y.

    2015-01-01

    By using 5.75 and 47.5 mT nuclear magnetic resonance (NMR) spectroscopy, up to 105-fold sensitivity enhancement through signal amplification by reversible exchange (SABRE) was enabled, and subsecond temporal resolution was used to monitor an exchange reaction that resulted in the buildup and decay of hyperpolarized species after parahydrogen bubbling. We demonstrated the high-resolution low-field proton magnetic resonance imaging (MRI) of pyridine in a 47.5 mT magnetic field endowed by SABRE. Molecular imaging (i.e. imaging of dilute hyperpolarized substances rather than the bulk medium) was conducted in two regimes: in situ real-time MRI of the reaction mixture (in which pyridine was hyperpolarized), and ex situ MRI (in which hyperpolarization decays) of the liquid hyperpolarized product. Low-field (milli-Tesla range, e.g. 5.75 and 47.5 mT used in this study) parahydrogen-enhanced NMR and MRI, which are free from the limitations of high-field magnetic resonance (including susceptibility-induced gradients of the static magnetic field at phase interfaces), potentially enables new imaging applications as well as differentiation of hyperpolarized chemical species on demand by exploiting spin manipulations with static and alternating magnetic fields. PMID:25367202

  10. Improving Assessment of Lipoprotein Profile in Type 1 Diabetes by 1H NMR Spectroscopy

    Science.gov (United States)

    Brugnara, Laura; Mallol, Roger; Ribalta, Josep; Vinaixa, Maria; Murillo, Serafín; Casserras, Teresa; Guardiola, Montse; Vallvé, Joan Carles; Kalko, Susana G.; Correig, Xavier; Novials, Anna

    2015-01-01

    Patients with type 1 diabetes (T1D) present increased risk of cardiovascular disease (CVD). The aim of this study is to improve the assessment of lipoprotein profile in patients with T1D by using a robust developed method 1H nuclear magnetic resonance spectroscopy (1H NMR), for further correlation with clinical factors associated to CVD. Thirty patients with T1D and 30 non-diabetes control (CT) subjects, matched for gender, age, body composition (DXA, BMI, waist/hip ratio), regular physical activity levels and cardiorespiratory capacity (VO2peak), were analyzed. Dietary records and routine lipids were assessed. Serum lipoprotein particle subfractions, particle sizes, and cholesterol and triglycerides subfractions were analyzed by 1H NMR. It was evidenced that subjects with T1D presented lower concentrations of small LDL cholesterol, medium VLDL particles, large VLDL triglycerides, and total triglycerides as compared to CT subjects. Women with T1D presented a positive association with HDL size (plipoprotein profile as compared to control counterparts. In addition, slight alterations in BMI and/or body fat composition showed to be relevant to provoking alterations in lipoproteins profiles. Finally, body fat composition appears to be a determinant for cardioprotector lipoprotein profile. PMID:26317989

  11. Structural characterization of homogalacturonan by NMR spectroscopy - assignment of reference compounds

    DEFF Research Database (Denmark)

    Petersen, Bent O.; Meier, Sebastian; Duus, Jens Øllgaard;

    2008-01-01

    Complete assignment of 1H and 13C NMR of six hexagalactopyranuronic acids with varying degree and pattern of methyl esterification is reported. The NMR experiments were run at room temperature using approximately 2 mg of sample making this method convenient for studying the structure of homogalac......Complete assignment of 1H and 13C NMR of six hexagalactopyranuronic acids with varying degree and pattern of methyl esterification is reported. The NMR experiments were run at room temperature using approximately 2 mg of sample making this method convenient for studying the structure...

  12. Area per lipid and cholesterol interactions in membranes from separated local-field (13)C NMR spectroscopy.

    Science.gov (United States)

    Leftin, Avigdor; Molugu, Trivikram R; Job, Constantin; Beyer, Klaus; Brown, Michael F

    2014-11-18

    Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state (13)C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved (13)C-(1)H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the (13)C-(1)H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state (13)C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive.

  13. Hadamard NMR spectroscopy for two-dimensional quantum information processing and parallel search algorithms.

    Science.gov (United States)

    Gopinath, T; Kumar, Anil

    2006-12-01

    Hadamard spectroscopy has earlier been used to speed-up multi-dimensional NMR experiments. In this work, we speed-up the two-dimensional quantum computing scheme, by using Hadamard spectroscopy in the indirect dimension, resulting in a scheme which is faster and requires the Fourier transformation only in the direct dimension. Two and three qubit quantum gates are implemented with an extra observer qubit. We also use one-dimensional Hadamard spectroscopy for binary information storage by spatial encoding and implementation of a parallel search algorithm.

  14. Fast 2D NMR Spectroscopy for In vivo Monitoring of Bacterial Metabolism in Complex Mixtures

    Directory of Open Access Journals (Sweden)

    Rupashree Dass

    2017-07-01

    Full Text Available The biological toolbox is full of techniques developed originally for analytical chemistry. Among them, spectroscopic experiments are very important source of atomic-level structural information. Nuclear magnetic resonance (NMR spectroscopy, although very advanced in chemical and biophysical applications, has been used in microbiology only in a limited manner. So far, mostly one-dimensional 1H experiments have been reported in studies of bacterial metabolism monitored in situ. However, low spectral resolution and limited information on molecular topology limits the usability of these methods. These problems are particularly evident in the case of complex mixtures, where spectral peaks originating from many compounds overlap and make the interpretation of changes in a spectrum difficult or even impossible. Often a suite of two-dimensional (2D NMR experiments is used to improve resolution and extract structural information from internuclear correlations. However, for dynamically changing sample, like bacterial culture, the time-consuming sampling of so-called indirect time dimensions in 2D experiments is inefficient. Here, we propose the technique known from analytical chemistry and structural biology of proteins, i.e., time-resolved non-uniform sampling. The method allows application of 2D (and multi-D experiments in the case of quickly varying samples. The indirect dimension here is sparsely sampled resulting in significant reduction of experimental time. Compared to conventional approach based on a series of 1D measurements, this method provides extraordinary resolution and is a real-time approach to process monitoring. In this study, we demonstrate the usability of the method on a sample of Escherichia coli culture affected by ampicillin and on a sample of Propionibacterium acnes, an acne causing bacterium, mixed with a dose of face tonic, which is a complicated, multi-component mixture providing complex NMR spectrum. Through our experiments

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Full text. Hydrogen bonds in liquids can be of crucial importance for solvent effects in spectroscopy. We have herein computed the nuclear magnetic spin-spin coupling constants (SSCC) involving 15N and 1H nuclei motivated by the relevance of these couplings for the indirect detection of the 15N chemical shifts. Such nJ(N,H) couplings are now also taken as probes for obtaining structural information in proteins. In this work, we focus on the J-couplings; a complete analysis of the NMR spectral data for the compounds studied can be found in previous papers. Thermal and solvent effects on the SSCCs of metronidazole (1) were studied computationally with appropriate quantum-chemical methods. Metronidazole may serve as a model compound to investigate the influence of solvent molecules on the NMR spin-spin coupling constants in heterocyclic rings. We find a hydrogen bond between 1 and a solvent water molecule that is associated with a bond critical point between the imidazole N-3 atom and a water H atom. AIM analysis indicates this hydrogen bond to be mainly electrostatic in nature. Simple static SSCC calculations in vacuo underestimate the nJ(N-3,H) coupling constants because of the neglect of hydrogen bonding. PCM-based treatments perform reasonably well because of the electrostatic character of the hydrogen bond. For more reliable predictions, it is important to take into account the dynamics of the system and to include nearby solvent molecules explicitly. The reduction of the hyperconjugative interactions involving the sigma CH bond or the sigma {sup *}CH antibond (with the coupling nucleus H) that is found in solution appears to be correlated to the reduction of coupling pathways in the imidazole ring. Since nuclear spin orientation information is transferred electronically to the other nuclei in the molecule, experimentally determined J-couplings directly reflect the nature of the chemical bond involved.106,107 Unlike most other NMR properties, which can be

  16. New methods and applications in solid-state NMR spectroscopy of quadrupolar nuclei.

    Science.gov (United States)

    Ashbrook, Sharon E; Sneddon, Scott

    2014-11-05

    Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future.

  17. Quantification of organic and amino acids in beer by 1H NMR spectroscopy.

    Science.gov (United States)

    Nord, Lars I; Vaag, Pia; Duus, Jens Ø

    2004-08-15

    The quantification of organic and amino acids in beer using 1H NMR spectroscopy is demonstrated. Quantification was made both by integration of signals in the spectra together with use of calibration references and by use of partial least-squares (PLS) regression. Results from the NMR quantifications were compared with those obtained from determinations by amino acid analysis on HPLC and organic acid analysis by capillary electrophoresis. The described NMR-based methods could satisfactorily be used for quantification of several of the investigated metabolites in beer down to approximately 10 mg/L and for most with a good to high accuracy compared to results obtained by HPLC and capillary electrophoresis (R2 0.90-0.99). This was achieved with a simple sample preparation and one-dimensional 1H NMR spectra obtained in a few minutes. The use of PLS clearly improves the accuracy of the quantifications, based on comparison to results obtained by HPLC and capillary electrophoresis, and furthermore permits the determination of components with partially overlapped signals in the spectrum. NMR spectroscopy in combination with PLS will be a useful tool for the quantification of metabolites, not only in beer but also in other beverages and biofluids.

  18. An NMR study on shale wettability

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  19. Encoded loop-lanthanide-binding tags for long-range distance measurements in proteins by NMR and EPR spectroscopy.

    Science.gov (United States)

    Barthelmes, Dominic; Gränz, Markus; Barthelmes, Katja; Allen, Karen N; Imperiali, Barbara; Prisner, Thomas; Schwalbe, Harald

    2015-11-01

    We recently engineered encodable lanthanide binding tags (LBTs) into proteins and demonstrated their applicability in Nuclear Magnetic Resonance (NMR) spectroscopy, X-ray crystallography and luminescence studies. Here, we engineered two-loop-LBTs into the model protein interleukin-1β (IL1β) and measured (1)H, (15)N-pseudocontact shifts (PCSs) by NMR spectroscopy. We determined the Δχ-tensors associated with each Tm(3+)-loaded loop-LBT and show that the experimental PCSs yield structural information at the interface between the two metal ion centers at atomic resolution. Such information is very valuable for the determination of the sites of interfaces in protein-protein-complexes. Combining the experimental PCSs of the two-loop-LBT construct IL1β-S2R2 and the respective single-loop-LBT constructs IL1β-S2, IL1β-R2 we additionally determined the distance between the metal ion centers. Further, we explore the use of two-loop LBTs loaded with Gd(3+) as a novel tool for distance determination by Electron Paramagnetic Resonance spectroscopy and show the NMR-derived distances to be remarkably consistent with distances derived from Pulsed Electron-Electron Dipolar Resonance.

  20. Quantitative analysis of amygdalin and prunasin in Prunus serotina Ehrh. using (1) H-NMR spectroscopy.

    Science.gov (United States)

    Santos Pimenta, Lúcia P; Schilthuizen, Menno; Verpoorte, Robert; Choi, Young Hae

    2014-01-01

    Prunus serotina is native to North America but has been invasively introduced in Europe since the seventeenth century. This plant contains cyanogenic glycosides that are believed to be related to its success as an invasive plant. For these compounds, chromatographic- or spectrometric-based (targeting on HCN hydrolysis) methods of analysis have been employed so far. However, the conventional methods require tedious preparation steps and a long measuring time. To develop a fast and simple method to quantify the cyanogenic glycosides, amygdalin and prunasin in dried Prunus serotina leaves without any pre-purification steps using (1) H-NMR spectroscopy. Extracts of Prunus serotina leaves using CH3 OH-d4 and KH2 PO4 buffer in D2 O (1:1) were quantitatively analysed for amygdalin and prunasin using (1) H-NMR spectroscopy. Different internal standards were evaluated for accuracy and stability. The purity of quantitated (1) H-NMR signals was evaluated using several two-dimensional NMR experiments. Trimethylsilylpropionic acid sodium salt-d4 proved most suitable as the internal standard for quantitative (1) H-NMR analysis. Two-dimensional J-resolved NMR was shown to be a useful tool to confirm the structures and to check for possible signal overlapping with the target signals for the quantitation. Twenty-two samples of P. serotina were subsequently quantitatively analysed for the cyanogenic glycosides prunasin and amygdalin. The NMR method offers a fast, high-throughput analysis of cyanogenic glycosides in dried leaves permitting simultaneous quantification and identification of prunasin and amygdalin in Prunus serotina. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Application of INEPT 109Ag and 15N NMR spectroscopy for the study of metal-ligand interaction of silver analogues of Copper(I) model compounds

    NARCIS (Netherlands)

    Koten, G. van; Stein, G.C. van; Brevard, C.

    1983-01-01

    Because of the presence of copper (in its reduced state) at active sites in protein it has become very important to study copper(I) model complexes by spectroscopic techniques.We now report that if copper(I) in model complexes can be substituted by silver(I) with retention of the structural features

  2. Recent Advances in Multinuclear NMR Spectroscopy for Chiral Recognition of Organic Compounds

    Directory of Open Access Journals (Sweden)

    Márcio S. Silva

    2017-02-01

    Full Text Available Nuclear magnetic resonance (NMR is a powerful tool for the elucidation of chemical structure and chiral recognition. In the last decade, the number of probes, media, and experiments to analyze chiral environments has rapidly increased. The evaluation of chiral molecules and systems has become a routine task in almost all NMR laboratories, allowing for the determination of molecular connectivities and the construction of spatial relationships. Among the features that improve the chiral recognition abilities by NMR is the application of different nuclei. The simplicity of the multinuclear NMR spectra relative to 1H, the minimal influence of the experimental conditions, and the larger shift dispersion make these nuclei especially suitable for NMR analysis. Herein, the recent advances in multinuclear (19F, 31P, 13C, and 77Se NMR spectroscopy for chiral recognition of organic compounds are presented. The review describes new chiral derivatizing agents and chiral solvating agents used for stereodiscrimination and the assignment of the absolute configuration of small organic compounds.

  3. Synthesis of [F3S(triple bond)NXeF][AsF6] and structural study by multi-NMR and Raman spectroscopy, electronic structure calculations, and X-ray crystallography.

    Science.gov (United States)

    Smith, Gregory L; Mercier, Hélène P A; Schrobilgen, Gary J

    2007-02-19

    The salt, [F3S(triple bond)NXeF][AsF6], has been synthesized by the reaction of [XeF][AsF6] with liquid N(triple bond)SF3 at -20 degrees C. The Xe-N bonded cation provides a rare example of xenon bound to an inorganic nitrogen base in which nitrogen is formally sp-hybridized. The F3S(triple bond)NXeF+ cation was characterized by Raman spectroscopy at -150 degrees C and by 129Xe, 19F, and 14N NMR spectroscopy in HF solution at -20 degrees C and in BrF5 solution at -60 degrees C. Colorless [F3S(triple bond)NXeF][AsF6] was crystallized from HF solvent at -45 degrees C, and its low-temperature X-ray crystal structure was determined. The Xe-N bond is among the longest Xe-N bonds known (2.236(4) A), whereas the Xe-F bond length (1.938(3) A) is significantly shorter than that of XeF2 but longer than in XeF+ salts. The Xe-F and Xe-N bond lengths are similar to those of HC(triple bond)NXeF+, placing it among the most ionic Xe-N bonds known. The nonlinear Xe-N-S angle (142.6(3)o) contrasts with the linear angle predicted by electronic structure calculations and is attributed to close N...F contacts within the crystallographic unit cell. Electronic structure calculations at the MP2 and DFT levels of theory were used to calculate the gas-phase geometries, charges, bond orders, and valencies of F3S(triple bond)NXeF+ and to assign vibrational frequencies. The calculated small energy difference (7.9 kJ mol-1) between bent and linear Xe-N-S angles also indicates that the bent geometry is likely the result of crystal packing. The structural studies, natural bond orbital analyses, and calculated gas-phase dissociation enthalpies reveal that F3S(triple bond)NXeF+ is among the weakest donor-acceptor adducts of XeF+ with an Xe-N donor-acceptor interaction that is very similar to that of HC(triple bond)NXeF+, but considerably stronger than that of F3S(triple bond)NAsF5. Despite the low dissociation enthalpy of the donor-acceptor bond in F3S(triple bond)NXeF+, 129Xe, 19F, and 14N NMR

  4. Anatomising proton NMR spectra with pure shift 2D J-spectroscopy: A cautionary tale

    Science.gov (United States)

    Kiraly, Peter; Foroozandeh, Mohammadali; Nilsson, Mathias; Morris, Gareth A.

    2017-09-01

    Analysis of proton NMR spectra has been a key tool in structure determination for over 60 years. A classic tool is 2D J-spectroscopy, but common problems are the difficulty of obtaining the absorption mode lineshapes needed for accurate results, and the need for a 45° shear of the final 2D spectrum. A novel 2D NMR method is reported here that allows straightforward determination of homonuclear couplings, using a modified version of the PSYCHE method to suppress couplings in the direct dimension. The method illustrates the need for care when combining pure shift data acquisition with multiple pulse methods.

  5. Solid-phase enolate chemistry investigated using HR-MAS NMR spectroscopy.

    Science.gov (United States)

    Fruchart, Jean-Sébastien; Lippens, Guy; Kuhn, Cyrille; Gras-Masse, Hélène; Melnyk, Oleg

    2002-01-25

    Supported P4-t-Bu enolate chemistry of phenylacetyloxymethyl polystyrene (PS) resin was investigated using high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Direct analysis of the crude reaction suspensions through the use of a diffusion filter (DF) allowed a rapid selection of the optimal experimental conditions, but also the characterization of the enolate on the solid phase. Comparison with solution experiments and literature data allowed us to address partially the structure of the enolate. HR-MAS NMR spectra of the enolate revealed also a tight interaction of P4-t-Bu base with the polymer matrix.

  6. Disclosing the multi-faceted world of weakly interacting inorganic systems by means of NMR spectroscopy.

    Science.gov (United States)

    Rocchigiani, Luca; Macchioni, Alceo

    2016-02-21

    The potential of NMR spectroscopy to investigate inorganic systems assembled by, or whose reactivity is affected by, non-covalent interactions is described. Subjects that have received particular attention in recent years (halogen bonding and Frustrated Lewis Pairs) and more classical subjects that remain under-explored (self-aggregation of ion pairs in low polar solvents, behavior of MAO containing metallocenium ion pairs, and hydrogen bonding/ion pairing effects in Au(i) catalysis) are considered, using an innovative approach, always focusing on the crucial information that can be provided by NMR.

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

    Directory of Open Access Journals (Sweden)

    Caroline Werner Pereira da Silva Grandizoli

    2014-01-01

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

  8. MEASURING VARIABILITY SOURCES IN NMR METABOLOMIC STUDIES

    OpenAIRE

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

    2013-01-01

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

  9. Study of Conformation and Dynamics of Molecules Adsorbed in Zeolites by 1H NMR

    Science.gov (United States)

    Michel, Dieter; Bohlmann, Winfried; Roland, Jorg; Mulla-Osman, Samir

    The chapter Study of Conformation and Dynamics of Molecules Adsorbed in Zeolites by 1H NMR is concerned with the application of high-resolution (HR) solid-state NMR techniques to study the behavior of molecules adsorbed on surfaces of nanoporous solids, such as zeolitic molecular sieves. This includes a combined or alternative application of conventional high-resolution NMR methods and of high-resolution solid-state NMR techniques, including magic-angle sample spinning (MAS), cross-polarization (CP), high-power decoupling and appropriate multiple-pulse sequences for two- or higher dimensional NMR and multiple-quantum spectroscopy. The interaction of adsorbed molecules with adsorption centers in the internal surfaces of porous solids does not only lead to changes in the reorientational and translational mobility of the molecular species but influences also the molecular conformation. Examples will be given for simple olefins in interaction with inner zeolite surfaces. Conclusions about the correlation times of the internal reorientational and translational dynamics are derived in complete agreement with the conclusion obtained from diffusion coefficients by means of PFG NMR (second chapter). Since the methodical approach of HR MAS NMR in heterogeneous systems presented here is also valuable for the investigation of lyotropic crystalline phases using HR MAS NMR (in Chap. 12) And for the NMR studies of cartilage (in Chap. 13) it was also the aim of this chapter to elucidate also the methodical background of these measurements in some more detail.

  10. Structural characterization of homogalacturonan by NMR spectroscopy-assignment of reference compounds.

    Science.gov (United States)

    Petersen, Bent O; Meier, Sebastian; Duus, Jens Ø; Clausen, Mads H

    2008-11-03

    Complete assignment of (1)H and (13)C NMR of six hexagalactopyranuronic acids with varying degree and pattern of methyl esterification is reported. The NMR experiments were run at room temperature using approximately 2mg of sample making this method convenient for studying the structure of homogalacturonan oligosaccharides.

  11. Stripline-based microfluidic devices for high-resolution NMR spectroscopy

    NARCIS (Netherlands)

    Bart, J.

    2009-01-01

    A novel route towards microchip integrated NMR analysis was studied. For NMR analysis of mass-limited samples, research has focussed for decennia on microsolenoidal or planar helical detection coils on microfluidic substrates. Since these approaches suffer from static field distortion resulting in

  12. 1020MHz single-channel proton fast magic angle spinning solid-state NMR spectroscopy.

    Science.gov (United States)

    Pandey, Manoj Kumar; Zhang, Rongchun; Hashi, Kenjiro; Ohki, Shinobu; Nishijima, Gen; Matsumoto, Shinji; Noguchi, Takashi; Deguchi, Kenzo; Goto, Atsushi; Shimizu, Tadashi; Maeda, Hideaki; Takahashi, Masato; Yanagisawa, Yoshinori; Yamazaki, Toshio; Iguchi, Seiya; Tanaka, Ryoji; Nemoto, Takahiro; Miyamoto, Tetsuo; Suematsu, Hiroto; Saito, Kazuyoshi; Miki, Takashi; Ramamoorthy, Ayyalusamy; Nishiyama, Yusuke

    2015-12-01

    This study reports a first successful demonstration of a single channel proton 3D and 2D high-throughput ultrafast magic angle spinning (MAS) solid-state NMR techniques in an ultra-high magnetic field (1020MHz) NMR spectrometer comprised of HTS/LTS magnet. High spectral resolution is well demonstrated.

  13. NMR Studies of Cartilage Dynamics, Diffusion, Degradation

    Science.gov (United States)

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

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

  14. On the exactness of effective Floquet Hamiltonians employed in solid-state NMR spectroscopy

    Science.gov (United States)

    Garg, Rajat; Ramachandran, Ramesh

    2017-05-01

    Development of theoretical models based on analytic theory has remained an active pursuit in molecular spectroscopy for its utility both in the design of experiments as well as in the interpretation of spectroscopic data. In particular, the role of "Effective Hamiltonians" in the evolution of theoretical frameworks is well known across all forms of spectroscopy. Nevertheless, a constant revalidation of the approximations employed in the theoretical frameworks is necessitated by the constant improvements on the experimental front in addition to the complexity posed by the systems under study. Here in this article, we confine our discussion to the derivation of effective Floquet Hamiltonians based on the contact transformation procedure. While the importance of the effective Floquet Hamiltonians in the qualitative description of NMR experiments has been realized in simpler cases, its extension in quantifying spectral data deserves a cautious approach. With this objective, the validity of the approximations employed in the derivation of the effective Floquet Hamiltonians is re-examined through a comparison with exact numerical methods under differing experimental conditions. The limitations arising from the existing analytic methods are outlined along with remedial measures for improving the accuracy of the derived effective Floquet Hamiltonians.

  15. Remeasuring HEWL pKa values by NMR spectroscopy 

    DEFF Research Database (Denmark)

    Webb, Helen; Tynan-Connolly, Barbara Mary; Lee, Gregory M;

    2011-01-01

    protonated carbons and protons in this protein. We extracted pK(a) values from the resulting titration curves using standard fitting methods, and compared these values to each other, and with those measured previously by ¹H NMR (Bartik et al., Biophys J 1994;66:1180–1184). This analysis gives insights......Site-specific pK(a) values measured by NMR spectroscopy provide essential information on protein electrostatics, the pH-dependence of protein structure, dynamics and function, and constitute an important benchmark for protein pK(a) calculation algorithms. Titration curves can be measured...... by tracking the NMR chemical shifts of several reporter nuclei versus sample pH. However, careful analysis of these curves is needed to extract residue-specific pK(a) values since pH-dependent chemical shift changes can arise from many sources, including through-bond inductive effects, through-space electric...

  16. Structures of larger proteins in solution: Three- and four-dimensional heteronuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gronenborn, A.M.; Clore, G.M. [National Institutes of Health, Bethesda, MD (United States)

    1994-12-01

    Complete understanding of a protein`s function and mechanism of action can only be achieved with a knowledge of its three-dimensional structure at atomic resolution. At present, there are two methods available for determining such structures. The first method, which has been established for many years, is x-ray diffraction of protein single crystals. The second method has blossomed only in the last 5 years and is based on the application of nuclear magnetic resonance (NMR) spectroscopy to proteins in solution. This review paper describes three- and four-dimensional NMR methods applied to protein structure determination and was adapted from Clore and Gronenborn. The review focuses on the underlying principals and practice of multidimensional NMR and the structural information obtained.

  17. High-resolution NMR and diffusion-ordered spectroscopy of port wine.

    Science.gov (United States)

    Nilsson, Mathias; Duarte, Iola F; Almeida, Cláudia; Delgadillo, Ivonne; Goodfellow, Brian J; Gil, Ana M; Morris, Gareth A

    2004-06-16

    The use of high-resolution NMR and high-resolution diffusion-ordered spectroscopy (DOSY) for the characterization of selected Port wine samples of different ages with the aim of identifying changes in composition is described. Conventional 1D and 2D NMR methods enabled the identification of about 35 compounds, including minor components such as some medium-chain alcohols, amino acids, and organic acids. High-resolution (HR) DOSY extended sample characterization, increasing the number of compounds identified and NMR assignments made, by providing information on the relative molecular sizes of the metabolites present. Port wines of different ages were found to differ mainly in their content of (a) organic acids and some amino acids, (b) an unidentified possible disaccharide, and (c) large aromatic species. The relative amount of these last high Mw aromatics is seen to decrease significantly in the oldest wine, as expected from the known formation and precipitation of anthocyanin-based polymers during red wine aging.

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

    Science.gov (United States)

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

    1993-02-05

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

  19. Solid-state (13)C CP MAS NMR spectroscopy of mushrooms gives directly the ratio between proteins and polysaccharides.

    Science.gov (United States)

    Pizzoferrato, L; Manzi, P; Bertocchi, F; Fanelli, C; Rotilio, G; Paci, M

    2000-11-01

    The solid-state (13)C CP MAS NMR technique has the potential of monitoring the chemical composition in the solid state of an intact food sample. This property has been utilized to study mushrooms of different species (Pleurotus ostreatus, Pleurotus eryngii, Pleurotus pulmunarius, and Lentinula edodes), already characterized by chemical analyses for protein and dietary fiber components. Solid-state (13)C CP MAS NMR spectroscopy reveals a large difference in the ratio between the glucidic and the proteic resonances probably depending on the mushroom species. An accurate inspection by model compounds and suitable mixtures of proteins and saccharides gives a methodology to interpret these experimental data. A good correlation (R(2) = 0.93; R(2) = 0.81) has been obtained by comparing the NMR data with the results of the chemical analyses. The results suggest the possibility to perform a taxonomic study and/or a nutritional study on the basis of the ratio between protein and polysaccharide levels determined by NMR or chemical methodologies.

  20. Establishing resolution-improved NMR spectroscopy in high magnetic fields with unknown spatiotemporal variations

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiyong; Cai, Shuhui; Zheng, Zhenyao; Lin, Yulan, E-mail: chenz@xmu.edu.cn, E-mail: lylfj2005@xmu.edu.cn; Chen, Zhong, E-mail: chenz@xmu.edu.cn, E-mail: lylfj2005@xmu.edu.cn [Department of Electronic Science, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen (China); Smith, Pieter E. S. [Chemical Physics Department, Weizmann Institute of Science, Rehovot (Israel)

    2015-12-28

    A half-century quest for higher magnetic fields has been an integral part of the progress undergone in the Nuclear Magnetic Resonance (NMR) study of materials’ structure and dynamics. Because 2D NMR relies on systematic changes in coherences’ phases as a function of an encoding time varied over a series of independent experiments, it generally cannot be applied in temporally unstable fields. This precludes most NMR methods from being used to characterize samples situated in hybrid or resistive magnets that are capable of achieving extremely high magnetic field strength. Recently, “ultrafast” NMR has been developed into an effective and widely applicable methodology enabling the acquisition of a multidimensional NMR spectrum in a single scan; it can therefore be used to partially mitigate the effects of temporally varying magnetic fields. Nevertheless, the strong interference of fluctuating fields with the spatial encoding of ultrafast NMR still severely restricts measurement sensitivity and resolution. Here, we introduce a strategy for obtaining high resolution NMR spectra that exploits the immunity of intermolecular zero-quantum coherences (iZQCs) to field instabilities and inhomogeneities. The spatial encoding of iZQCs is combined with a J-modulated detection scheme that removes the influence of arbitrary field inhomogeneities during acquisition. This new method can acquire high-resolution one-dimensional NMR spectra in large inhomogeneous and fluctuating fields, and it is tested with fields experimentally modeled to mimic those of resistive and resistive-superconducting hybrid magnets.

  1. 1H HR-MAS NMR Spectroscopy and the Metabolite Determination of Typical Foods in Mediterranean Diet

    Directory of Open Access Journals (Sweden)

    Carmelo Corsaro

    2015-01-01

    Full Text Available NMR spectroscopy has become an experimental technique widely used in food science. The experimental procedures that allow precise and quantitative analysis on different foods are relatively simple. For a better sensitivity and resolution, NMR spectroscopy is usually applied to liquid sample by means of extraction procedures that can be addressed to the observation of particular compounds. For the study of semisolid systems such as intact tissues, High-Resolution Magic Angle Spinning (HR-MAS has received great attention within the biomedical area and beyond. Metabolic profiling and metabolism changes can be investigated both in animal organs and in foods. In this work we present a proton HR-MAS NMR study on the typical vegetable foods of Mediterranean diet such as the Protected Geographical Indication (PGI cherry tomato of Pachino, the PGI Interdonato lemon of Messina, several Protected Designation of Origin (PDO extra virgin olive oils from Sicily, and the Traditional Italian Food Product (PAT red garlic of Nubia. We were able to identify and quantify the main metabolites within the studied systems that can be used for their characterization and authentication.

  2. In vivo NMR spectroscopy of the liver. Spectroscopie RMN du foie in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Jehenson, P.; Cuenod, C.A.; Syrota, A. (CEA, 91 - Orsay (FR). Service Hospitalier Frederic Joliot)

    1989-01-01

    The application of in vivo MR spectroscopy to the study of the liver is currently an expanding field of research. Owing to technical difficulties, the results obtained thus far were mainly those of animal observations. Several nuclei have been considered: hydrogen, phosphorus, carbon or fluorine. This non-traumatic method allows following and quantifying the various metabolic pathways, especially during hepatic diseases. The major metabolic pathways, i.e. neoglycogenesis, glycogenolysis, Krebs' cycle, etc., are studied, as well as their alterations during diseases such as ischemia, diabetes or alcoholism. The development of this promising technique requires the cooperation of various clinical and fundamental disciplines.

  3. Variability within intramuscular fat content of pigs as measured by gravimetry, FTIR and NMR spectroscopy.

    Science.gov (United States)

    Geers, R; Decanniere, C; Villé, H; Van Hecke, P; Bosschaerts, L

    1995-01-01

    In order to determine in vivo intramuscular fat content of pigs' biceps femoris, three methods were compared. Gravimetry and FTIR spectroscopy after total fat extraction from a biopsy (about 400 mg skeletal muscle tissue) and in vivo (1)H NMR spectroscopy after imaging and volume of interest selection were used. Mean values (g fat/100 g fresh tissue) were, respectively, 1·47 ± 0·35 (gravimetry), 1·26 ± 0·33 (FTIR) and 0·51 ± 0·19 (NMR); but NMR-values represented only triglycerides. Within an intramuscular fat range from 1·1 to 2·7 g per 100 g fresh muscle tissue, possible to estimate a calibration line between the in vitro and in vivo data for hybrid piglets of about 18 kg. Repeated in vivo NMR measurements on the same muscle volume showed a mean coefficient of variation of 5·5 ± 2·7%. The coefficient of variation of measurements on different volumes within the same muscle was 14 ± 10%. The mean intramuscular fat content of 18 kg or 100 kg pigs was, respectively, 1·64 ± 0·46 (biceps femoris) and 1·32 ± 0·1 (longissimus dorsi) g per 100 g fresh muscle tissue.

  4. Analyzing the adsorption of blood plasma components by means of fullerene-containing silica gels and NMR spectroscopy in solids

    Science.gov (United States)

    Melenevskaya, E. Yu.; Mokeev, M. V.; Nasonova, K. V.; Podosenova, N. G.; Sharonova, L. V.; Gribanov, A. V.

    2012-10-01

    The results from studying the adsorption of blood plasma components (e.g., protein, triglycerides, cholesterol, and lipoproteins of low and high density) using silica gels modified with fullerene molecules (in the form of C60 or the hydroxylated form of C60(OH) x ) and subjected to hydration (or, alternatively, dehydration) are presented. The conditions for preparing adsorbents that allow us to control the adsorption capacity of silica gel and the selectivity of adsorption toward the components of blood plasma, are revealed. The nature and strength of the interactions of the introduced components (fullerene molecules and water) with functional groups on the silica surface are studied by means of solid state NMR spectroscopy (NMR-SS). Conclusions regarding the nature of the centers that control adsorption are drawn on the basis of NMR-SS spectra in combination with direct measurements of adsorption. The interaction of the oxygen of the hydroxyl group of silica gel with fullerene, leading to the formation of electron-donor complexes of C60-H, C60-OH, or C60-OSi type, is demonstrated by the observed changes in the NMR-SS spectra of silica gels in the presence of fullerene.

  5. Analysis of Structural Variability in Pharmaceutical Excipients Using Solid-State NMR Spectroscopy

    OpenAIRE

    Sperger, Diana M.; Munson, Eric Jon

    2011-01-01

    Polysaccharide-based excipients comprise the majority of most solid dosage forms and can vary dramatically in terms of structural and functionally related properties. Analytical methods for characterizing these important formulation components are crucial. Solid-state NMR spectroscopy (SSNMR) can provide a wealth of information on these materials while offering the advantages of non-destructive sample preparation and selectivity. The overall objective of this work is to identify SSNMR paramet...

  6. Authentication of beef versus horse meat using 60 MHz 1H NMR spectroscopy

    OpenAIRE

    Jakes, W.; Gerdova, A.; Defernez, M.; Watson, A. D.; McCallum, C.; Limer, E.; Colquhoun, I. J.; Williamson, D. C.; Kemsley, E.K.

    2015-01-01

    This work reports a candidate screening protocol to distinguish beef from horse meat based upon comparison of triglyceride signatures obtained by 60 MHz 1H NMR spectroscopy. Using a simple chloroform-based extraction, we obtained classic low-field triglyceride spectra from typically a 10 min acquisition time. Peak integration was sufficient to differentiate samples of fresh beef (76 extractions) and horse (62 extractions) using Naïve Bayes classification. Principal component analysis gave a t...

  7. Metabolite profiling of Curcuma species grown in different regions using 1H NMR spectroscopy and multivariate analysis.

    Science.gov (United States)

    Jung, Youngae; Lee, Jueun; Kim, Ho Kyoung; Moon, Byeong Cheol; Ji, Yunui; Ryu, Do Hyun; Hwang, Geum-Sook

    2012-12-07

    Curcuma is used to treat skin diseases and colic inflammatory disorders, and in insect repellants and antimicrobial and antidiabetic medications. Two Curcuma species (C. aromatica and C. longa) grown in Jeju-do and Jin-do were used in this study. Methanolic extracts were analyzed by (1)H NMR spectroscopy, and metabolite profiling coupled with multivariate analysis was applied to characterize the differences between species or origin. PCA analysis showed significantly greater differences between species than origins, and the metabolites responsible for the differences were identified. The concentrations of sugars (glucose, fructose, and sucrose) and essential oils (eucalyptol, curdione, and germacrone) were significantly different between the two species. However, the samples from Jeju-do and Jin-do were different mainly in their concentrations of organic acids (fumarate, succinate, acetate, and formate) and sugars. This study demonstrates that NMR-based metabolomics is an efficient method for fingerprinting and determining differences between Curcuma species or those grown in different regions.

  8. Identification of the Glycosaminoglycan Binding Site of Interleukin-10 by NMR Spectroscopy.

    Science.gov (United States)

    Künze, Georg; Köhling, Sebastian; Vogel, Alexander; Rademann, Jörg; Huster, Daniel

    2016-02-05

    The biological function of interleukin-10 (IL-10), a pleiotropic cytokine with an essential role in inflammatory processes, is known to be affected by glycosaminoglycans (GAGs). GAGs are highly negatively charged polysaccharides and integral components of the extracellular matrix with important functions in the biology of many growth factors and cytokines. The molecular mechanism of the IL-10/GAG interaction is unclear. In particular, experimental evidence about IL-10/GAG binding sites is lacking, despite its importance for understanding the biological role of the interaction. Here, we report the experimental determination of a GAG binding site of IL-10. Although no co-crystal structure of the IL-10·GAG complex could be obtained, its structural characterization was possible by NMR spectroscopy. Chemical shift perturbations of IL-10 induced by GAG binding were used to narrow down the location of the binding site and to assess the affinity for different GAG molecules. Subsequent observation of NMR pseudocontact shifts of IL-10 and its heparin ligand, as induced by a protein-attached lanthanide spin label, provided structural restraints for the protein·ligand complex. Using these restraints, pseudocontact shift-based rigid body docking together with molecular dynamics simulations yielded a GAG binding model. The heparin binding site is located at the C-terminal end of helix D and the adjacent DE loop and coincides with a patch of positively charged residues involving arginines 102, 104, 106, and 107 and lysines 117 and 119. This study represents the first experimental characterization of the IL-10·GAG complex structure and provides the starting point for revealing the biological significance of the interaction of IL-10 with GAGs.

  9. Synthesis, characterization and spectroscopy studying of some metal complexes of a new Schiff base ligand; X-ray crystal structure, NMR and IR investigation of a new dodecahedron Cd(II) complex

    Science.gov (United States)

    Golbedaghi, Reza; Rezaeivala, Majid; Khalili, Maryam; Notash, Behrouz; Karimi, Javad

    2016-12-01

    Some new [Cd(H2L1)(NO3)]ClO4 (1), [Mn(H2L1)](ClO4)2 (2), [Ni(H2L1)](ClO4)2 (3) and [Cu(H2L1)](ClO4)2 (4) complexes were prepared by the reaction of a Schiff base ligand and M (II) metal ions in equimolar ratios (M = Cd, Mn, Ni and Cu). The ligand H2L1 was synthesized by reaction of 2-[2-(3-formyl phenoxy)propoxy]benzaldehyde and ethanol amine and characterized by IR, 1H,13C NMR spectroscopy and elemental analysis. The synthesized complexes were characterized with IR and elemental analysis in all cases and 1H, 13C NMR, and X-ray in the case of Cd(II) complex. The X-ray crystal structure of compound 1 showed that all nitrogen and oxygen atoms of Schiff base ligand (N2O4) and a molecule of nitrate with two donor oxygen atom have been coordinated to the metal ion and the Cd(II) ion is in an eight-coordinate environment that is best described as a distorted dodecahedron geometry.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-01

    The development of fast magic angle spinning (MAS) opened up an opportunity for the indirect detection of insensitive low-γ nuclei (e.g., 13C and 15N) via the sensitive high-{gamma} nuclei (e.g., 1H and 19F) in solid-state NMR, with advanced sensitivity and resolution. In this thesis, new methodology utilizing fast MAS is presented, including through-bond indirectly detected heteronuclear correlation (HETCOR) spectroscopy, which is assisted by multiple RF pulse sequences for 1H-1H homonuclear decoupling. Also presented is a simple new strategy for optimization of 1H-1H homonuclear decoupling. As applications, various classes of materials, such as catalytic nanoscale materials, biomolecules, and organic complexes, are studied by combining indirect detection and other one-dimensional (1D) and two-dimensional (2D) NMR techniques. Indirectly detected through-bond HETCOR spectroscopy utilizing refocused INEPT (INEPTR) mixing was developed under fast MAS (Chapter 2). The time performance of this approach in 1H detected 2D 1H{l_brace}13C{r_brace} spectra was significantly improved, by a factor of almost 10, compared to the traditional 13C detected experiments, as demonstrated by measuring naturally abundant organic-inorganic mesoporous hybrid materials. The through-bond scheme was demonstrated as a new analytical tool, which provides complementary structural information in solid-state systems in addition to through-space correlation. To further benefit the sensitivity of the INEPT transfer in rigid solids, the combined rotation and multiple-pulse spectroscopy (CRAMPS) was implemented for homonuclear 1H decoupling under fast MAS (Chapter 3). Several decoupling schemes (PMLG5m$\\bar{x}$, PMLG5mm$\\bar{x}$x and SAM3) were analyzed to maximize the performance of through-bond transfer based

  11. Study of NMR porosity for terrestrial formation in China

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaowen; XIAO Lizhi; XIE Ranhong; ZHANG Yuanzhong

    2006-01-01

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

  12. Characterization of plant-derived carbon and phosphorus in lakes by sequential fractionation and 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); Wu, Fengchang, E-mail: wufengchang@vip.skleg.cn [State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Meng, Wei [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); 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)

    2016-10-01

    Although debris from aquatic macrophytes is one of the most important endogenous sources of organic matter (OM) and nutrients in lakes, its biogeochemical cycling and contribution to internal load of nutrients in eutrophic lakes are still poorly understood. In this study, sequential fractionation by H{sub 2}O, 0.1 M NaOH and 1.0 M HCl, combined with {sup 13}C and {sup 31}P NMR spectroscopy, was developed and used to characterize organic carbon (C) and phosphorus (P) in six aquatic plants collected from Tai Lake (Ch: Taihu), China. Organic matter, determined by total organic carbon (TOC), was unequally distributed in H{sub 2}O (21.2%), NaOH (29.9%), HCl (3.5%) and residual (45.3%) fractions. For P in debris of aquatic plants, 53.3% was extracted by H{sub 2}O, 31.9% by NaOH, and 11% by HCl, with 3.8% in residual fractions. Predominant OM components extracted by H{sub 2}O and NaOH were carbohydrates, proteins and aliphatic acids. Inorganic P (P{sub i}) was the primary form of P in H{sub 2}O fractions, whereas organic P (P{sub o}) was the primary form of P in NaOH fractions. The subsequent HCl fractions extracted fewer species of C and P. Some non-extractable carbohydrates, aromatics and metal phytate compounds remained in residual fractions. Based on sequential extraction and NMR analysis, it was proposed that those forms of C (54.7% of TOC) and P (96.2% of TP) in H{sub 2}O, NaOH and HCl fractions are potentially released to overlying water as labile components, while those in residues are stable and likely preserved in sediments of lakes. These results will be helpful in understanding internal loading of nutrients from debris of aquatic macrophytes and their recycling in lakes. - Highlights: • Sequential fractionation combined with NMR analysis was applied on aquatic plants. • Labile and stable C and P forms in aquatic plants were characterized. • 54.7% of OM and 96.2% of P in aquatic plants are potentially available. • 45.3% of OM and 3.8% of P in aquatic

  13. Assessing the fate and transformation of plant residues in the terrestrial environment using HR-MAS NMR spectroscopy

    Science.gov (United States)

    Kelleher, Brian P.; Simpson, Myrna J.; Simpson, Andre J.

    2006-08-01

    Plant litter decomposition plays a fundamental role in carbon and nitrogen cycles, provides key nutrients to the soil environment and represents a potentially large positive feedback to atmospheric CO 2. However, the full details of decomposition pathways and products are unknown. Here we present the first application of HR-MAS NMR spectroscopy on 13C and 15N labeled plant materials, and apply this approach in a preliminary study to monitor the environmental degradation of the pine and wheatgrass residues over time. In HR-MAS, is it possible to acquire very high resolution NMR data of plant biomass, and apply the vast array of multidimensional experiments available in conventional solution-state NMR. High levels of isotopic enrichment combined with HR-MAS significantly enhance the detection limits, and provide a wealth of information that is unattainable by any other method. Diffusion edited HR-MAS NMR data reveal the rapid loss of carbohydrate structures, while two-dimensional (2-D) HR-MAS NMR spectra demonstrate the relatively fast loss of both hydrolysable and condensed tannin structures from all plant tissues studied. Aromatic (partially lignin) and aliphatic components (waxes, cuticles) tend to persist, along with a small fraction of carbohydrate, and become highly functionalized over time. While one-dimensional (1-D) 13C HR-MAS NMR spectra of fresh plant tissue reflect compositional differences between pine and grass, these differences become negligible after decomposition suggesting that recalcitrant carbon may be similar despite the plant source. Two-dimensional 1H- 15N HR-MAS NMR analysis of the pine residue suggests that nitrogen from specific peptides is either selectively preserved or used for the synthesis of what appears to be novel structures. The amount of relevant data generated from plant components in situ using HR-MAS NMR is highly encouraging, and demonstrates that complete assignment will yield unprecedented structural knowledge of plant cell

  14. Alternatives to Nuclear Overhauser Enhancement Spectroscopy Presat and Carr-Purcell-Meiboom-Gill Presat for NMR-Based Metabolomics.

    Science.gov (United States)

    Le Guennec, Adrien; Tayyari, Fariba; Edison, Arthur S

    2017-09-05

    NMR metabolomics are primarily conducted with 1D nuclear Overhauser enhancement spectroscopy (NOESY) presat for water suppression and Carr-Purcell-Meiboom-Gill (CPMG) presat as a T2 filter to remove macromolecule signals. Others pulse sequences exist for these two objectives but are not often used in metabolomics studies, because they are less robust or unknown to the NMR metabolomics community. However, recent improvements on alternative pulse sequences provide attractive alternatives to 1D NOESY presat and CPMG presat. We focus this perspective on PURGE, a water suppression technique, and PROJECT presat, a T2 filter. These two pulse sequences, when optimized, performed at least on par with 1D NOESY presat and CPMG presat, if not better. These pulse sequences were tested on common samples for metabolomics, human plasma, and urine.

  15. In-situ annotation of carbohydrate diversity, abundance, and degradability in highly complex mixtures using NMR spectroscopy

    DEFF Research Database (Denmark)

    Meier, Sebastian

    2014-01-01

    Many functions of carbohydrates depend on the detection of short structural motifs, approximately up to hexasaccharide length, by receptors or catalysts. This study investigates the usefulness of state-of-the-art 1H–13C nuclear-magnetic-resonance (NMR) spectroscopy for characterizing the diversity......, abundance, and degradability of such short structural motifs in plant-derived carbohydrates. Assignments of carbohydrate signals for 1H–13C NMR spectra of beer, wine, and fruit juice yield up to >130 assignments in situ, i.e. in individual samples without separation or derivatization. More than 500...... structural motifs can be resolved over a concentration range of ~103 in experiments of a few hours duration. The diversity of carbohydrate units increases according to power laws at lower concentrations for both cereal and fruit-derived samples. Simple graphs resolve the smaller overall contribution of more...

  16. Si-29 NMR spectroscopy of naturally-shocked quartz from Meteor Crater, Arizona: Correlation to Kieffer's classification scheme

    Science.gov (United States)

    Boslough, M. B.; Cygan, R. T.; Kirkpatrick, R. J.

    1993-01-01

    We have applied solid state Si-29 nuclear magnetic resonance (NMR) spectroscopy to five naturally-shocked Coconino Sandstone samples from Meteor Crater, Arizona, with the goal of examining possible correlations between NMR spectral characteristics and shock level. This work follows our observation of a strong correlation between the width of a Si-29 resonance and peak shock pressure for experimentally shocked quartz powders. The peak width increase is due to the shock-induced formation of amorphous silica, which increases as a function of shock pressure over the range that we studied (7.5 to 22 GPa). The Coconino Sandstone spectra are in excellent agreement with the classification scheme of Kieffer in terms of presence and approximate abundances of quartz, coesite, stishovite, and glass. We also observe a new resonance in two moderately shocked samples that we have tentatively identified with silicon in tetrahedra with one hydroxyl group in a densified form of amorphous silica.

  17. Conformational analysis of 3-(trimethylsilyl)propionic acid by NMR spectroscopy: an unusual expression of the beta-silyl effect.

    Science.gov (United States)

    Nkansah, Richard A; Gerken, James B; Roberts, John D

    2007-08-31

    The rotational freedom of the carbon-carbon single bonds of 1,2-disubstituted ethanes affords the possibility of these compounds existing as a rapidly interconverting mixture of conformers in solution. The conformational preferences of one such compound, 3-(trimethylsilyl)propionic acid, and its anion were studied in water, dimethyl sulfoxide, methanol, ethanol, isopropyl alcohol, tert-butyl alcohol, tetrahydrofuran, and toluene with 1H NMR spectroscopy. The conformational preferences were determined from the vicinal proton-proton coupling constants between the hydrogen nuclei of the CH(2)CH(2) group with the aid of the Altona equations to derive the equilibrium anti and gauche percentages of rotamers from the averaged NMR-time scale couplings. Conformational analyses of 4,4-dimethylpentanoic acid and its anion as well as 2-(trimethylsilyl)ethanesulfonate anion were also conducted to compare the relative structural influences on the conformational preferences of silicon and carbon.

  18. Spanning or looping? The order and conformation of bipolar phospholipids in lipid membranes using 2H NMR spectroscopy.

    Science.gov (United States)

    Cuccia, L A; Morin, F; Beck, A; Hébert, N; Just, G; Lennox, R B

    2000-12-01

    Solid-state 2H NMR spectroscopy was used to study and characterize the conformation and order of bolaform lipid membranes. A series of 2H-labeled bolaform phosphatidylcholines has been synthesized and their properties compared to a [D4]dimyristoylphosphatidylcholine (DMPC) and a [D8]-32 macrocyclic phosphatidylcholine. 31P NMR measurements establish that the aqueous dispersions of these lipids adopt lamellar phases. Computational dePakeing was used to extract the spectrum of the oriented system from spectra consisting of a superposition of randomly oriented domains in an unoriented sample. A large (> 90 %) and constant value for the normalized segmental order parameter (Smol) was observed for all positions along the diacyl chain of the bolaform lipids and only a small population ( 90%) of the bolaform lipids is assigned to a highly ordered, spanning conformer.

  19. NMR study of magnetism and superparamagnetism

    Science.gov (United States)

    Yuan, Shaojie

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

  20. EPR and NMR spectroscopy on spin-labeled proteins

    NARCIS (Netherlands)

    Finiguerra, Michelina Giuseppina

    2011-01-01

    Spin labeling and electron paramagnetic resonance (EPR) have been employed to study structure and dynamics of proteins. The surface polarity of four single cysteine mutants of the Zn-azurin in frozen solution were studied using 275 GHz EPR (J-band), with the advantage compared to 9 GHz (X-band) and

  1. Investigating fatty acids inserted into magnetically aligned phospholipid bilayers using EPR and solid-state NMR spectroscopy

    Science.gov (United States)

    Nusair, Nisreen A.; Tiburu, Elvis K.; Dave, Paresh C.; Lorigan, Gary A.

    2004-06-01

    This is the first time 2H solid-state NMR spectroscopy and spin-labeled EPR spectroscopy have been utilized to probe the structural orientation and dynamics of a stearic acid incorporated into magnetically aligned phospholipid bilayers or bicelles. The data gleaned from the two different techniques provide a more complete description of the bilayer membrane system. Both methods provided similar qualitative information on the phospholipid bilayer, high order, and low motion for the hydrocarbon segment close to the carboxyl groups of the stearic acid and less order and more rapid motion at the end towards the terminal methyl groups. However, the segmental order parameters differed markedly due to the different orientations that the nitroxide and C-D bond axes transform with the various stearic acid acyl chain conformations, and because of the difference in dynamic sensitivity between NMR and EPR over the timescales examined. 5-, 7-, 12-, and 16-doxylstearic acids spin-labels were used in the EPR experiments and stearic acid-d 35 was used in the solid-state NMR experiments. The influence of the addition of cholesterol and the variation of temperature on the fatty acid hydrocarbon chain ordering in the DMPC/DHPC phospholipid bilayers was also studied. Cholesterol increased the degree of ordering of the hydrocarbon chains. Conversely, as the temperature of the magnetically aligned phospholipid bilayers increased, the order parameters decreased due to the higher random motion of the acyl chain of the stearic acid. The results indicate that magnetically aligned phospholipid bilayers are an excellent model membrane system and can be used for both NMR and EPR studies.

  2. 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.

  3. Quantification of Water-Soluble Metabolites in Medicinal Mushrooms Using Proton NMR Spectroscopy.

    Science.gov (United States)

    Lo, Yu-Chang; Chien, Shih-Chang; Mishchuk, Darya O; Slupsky, Carolyn M; Mau, Jeng-Leun

    2016-01-01

    The water-soluble metabolites in 5 mushrooms were identified and quantified using proton nuclear magnetic resonance (NMR) spectroscopy and software for targeted metabolite detection and quantification. In total, 35 compounds were found in Agaricus brasiliensis, 25 in Taiwanofungus camphoratus, 23 in Ganoderma lucidum (Taiwan) and Lentinus edodes, and 16 in G. lucidum (China). Total amounts of all identified metabolites in A. brasiliensis, T. camphoratus, G. lucidum, G. lucidum (China), and L. edodes were 149,950.51, 12,834.18, 9,549.09, 2,788.41, and 111,726.51 mg/kg dry weight, respectively. These metabolites were categorized into 4 groups: free amino acids and derivatives, carbohydrates, carboxylic acids, and nucleosides. Carbohydrates were the most abundant metabolites among all 4 groups, with mannitol having the highest concentration among all analyzed metabolites (848-94,104 mg/kg dry weight). Principal components analysis (PCA) showed obvious distinction among the metabolites of the 5 different kinds of mushrooms analyzed in this study. Thus PCA could provide an optional analytical way of identifying and recognizing the compositions of flavor products. Furthermore, the results of this study demonstrate that NMRbased metabolomics is a powerful tool for differentiating between various medicinal mushrooms.

  4. NMR spectroscopy reveals the presence and association of lipids and keratin in adhesive gecko setae

    Science.gov (United States)

    Jain, Dharamdeep; Stark, Alyssa Y.; Niewiarowski, Peter H.; Miyoshi, Toshikazu; Dhinojwala, Ali

    2015-01-01

    Lipid and protein aggregates are one of the fundamental materials of biological systems. Examples include cell membranes, insect cuticle, vertebrate epidermis, feathers, hair and adhesive structures known as ‘setae’ on gecko toes. Until recently gecko setae were assumed to be composed entirely of keratin, but analysis of footprints left behind by geckos walking on surfaces revealed that setae include various kinds of lipids. However, the arrangement and molecular-level behavior of lipids and keratin in the setae is still not known. In the present study we demonstrate, for the first time, the use of Nuclear Magnetic Resonance (NMR) spectroscopy techniques to confirm the presence of lipids and investigate their association with keratin in ‘pristine' sheds, or natural molts of the adhesive toe pad and non-adhesive regions of the skin. Analysis was also carried on the sheds after they were ‘delipidized’ to remove surface lipids. Our results show a distribution of similar lipids in both the skin and toe shed but with different dynamics at a molecular level. The present study can help us understand the gecko system both biologically and for design of synthetic adhesives, but the findings may be relevant to the characteristics of lipid-protein interactions in other biological systems. PMID:25902194

  5. NMR-based approach to the analysis of radiopharmaceuticals: radiochemical purity, specific activity, and radioactive concentration values by proton and tritium NMR spectroscopy.

    Science.gov (United States)

    Schenk, David J; Dormer, Peter G; Hesk, David; Pollack, Scott R; Lavey, Carolee Flader

    2015-06-15

    Compounds containing tritium are widely used across the drug discovery and development landscape. These materials are widely utilized because they can be efficiently synthesized and produced at high specific activity. Results from internally calibrated (3)H and (1)H nuclear magnetic resonance (NMR) spectroscopy suggests that at least in some cases, this calibrated approach could supplement or potentially replace radio-high-performance liquid chromatography for radiochemical purity, dilution and scintillation counting for the measurement of radioactivity per volume, and liquid chromatography/mass spectrometry analysis for the determination of specific activity. In summary, the NMR-derived values agreed with those from the standard approaches to within 1% to 9% for solution count and specific activity. Additionally, the NMR-derived values for radiochemical purity deviated by less than 5%. A benefit of this method is that these values may be calculated at the same time that (3)H NMR analysis provides the location and distribution of tritium atoms within the molecule. Presented and discussed here is the application of this method, advantages and disadvantages of the approach, and a rationale for utilizing internally calibrated (1)H and (3)H NMR spectroscopy for specific activity, radioactive concentration, and radiochemical purity whenever acquiring (3)H NMR for tritium location. Copyright © 2015 John Wiley & Sons, Ltd.

  6. An NMR study of adsorbed helium films

    Science.gov (United States)

    Kent, Anthony Joseph

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

  7. Phosphorolytic activity of Escherichia coli glycyl-tRNA synthetase towards its cognate aminoacyl adenylate detected by 31P-NMR spectroscopy and thin-layer chromatography

    DEFF Research Database (Denmark)

    Led, Jens Jørgen; Switon, Werner K.; Jensen, Kaj Frank

    1983-01-01

    The catalytic activity of highly purified Escherichia coli glycyl-tRNA synthetase has been studied by 31P-NMR spectroscopy and thin-layer chromatography on poly(ethyleneimine)-cellulose. It was found that this synthetase, besides the activation of its cognate amino acid and the syntheses...

  8. Structure-Correlation NMR Spectroscopy for Macromolecules Using Repeated Bidirectional Photoisomerization of Azobenzene.

    Science.gov (United States)

    Nagashima, Toshio; Ueda, Keisuke; Nishimura, Chiaki; Yamazaki, Toshio

    2015-11-17

    Control over macromolecular structure offers bright potentials for manipulation of macromolecular functions. We here present structure-correlation NMR spectroscopy to analyze the correlation between polymorphic macromolecular structures driven by photoisomerization of azobenzene. The structural conversion of azobenzene was induced within the mixing time of a NOESY experiment using a colored light source, and the reverse structural conversion was induced during the relaxation delay using a light source of another color. The correlation spectrum between trans- and cis-azobenzene was then obtained. To maximize the efficiency of the bidirectional photoisomerization of azobenzene-containing macromolecules, we developed a novel light-irradiation NMR sample tube and method for irradiating target molecules in an NMR radio frequency (rf) coil. When this sample tube was used for photoisomerization of an azobenzene derivative at a concentration of 0.2 mM, data collection with reasonable sensitivity applicable to macromolecules was achieved. We performed isomerization of an azobenzene-cross-linked peptide within the mixing time of a NOESY experiment that produced cross-peaks between helix and random-coil forms of the peptide. Thus, these results indicate that macromolecular structure manipulation can be incorporated into an NMR pulse sequence using an azobenzene derivative and irradiation with light of two types of wavelengths, providing a new method for structural analysis of metastable states of macromolecules.

  9. Metabolomic Fingerprinting of Romaneschi Globe Artichokes by NMR Spectroscopy and Multivariate Data Analysis.

    Science.gov (United States)

    de Falco, Bruna; Incerti, Guido; Pepe, Rosa; Amato, Mariana; Lanzotti, Virginia

    2016-09-01

    Globe artichoke (Cynara cardunculus L. var. scolymus L. Fiori) and cardoon (Cynara cardunculus L. var. altilis DC) are sources of nutraceuticals and bioactive compounds. To apply a NMR metabolomic fingerprinting approach to Cynara cardunculus heads to obtain simultaneous identification and quantitation of the major classes of organic compounds. The edible part of 14 Globe artichoke populations, belonging to the Romaneschi varietal group, were extracted to obtain apolar and polar organic extracts. The analysis was also extended to one species of cultivated cardoon for comparison. The (1) H-NMR of the extracts allowed simultaneous identification of the bioactive metabolites whose quantitation have been obtained by spectral integration followed by principal component analysis (PCA). Apolar organic extracts were mainly based on highly unsaturated long chain lipids. Polar organic extracts contained organic acids, amino acids, sugars (mainly inulin), caffeoyl derivatives (mainly cynarin), flavonoids, and terpenes. The level of nutraceuticals was found to be highest in the Italian landraces Bianco di Pertosa zia E and Natalina while cardoon showed the lowest content of all metabolites thus confirming the genetic distance between artichokes and cardoon. Metabolomic approach coupling NMR spectroscopy with multivariate data analysis allowed for a detailed metabolite profile of artichoke and cardoon varieties to be obtained. Relevant differences in the relative content of the metabolites were observed for the species analysed. This work is the first application of (1) H-NMR with multivariate statistics to provide a metabolomic fingerprinting of Cynara scolymus. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vagner Fernandes Knupp

    2009-02-01

    Full Text Available Friedelin (1, 3b-friedelinol (2, 28-hydroxyfriedelin (3, 16a-hydroxyfriedelin (4, 30-hydroxyfriedelin (5 and 16a,28-dihydroxyfriedelin (6 were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl3 solution, 16a-hydroxyfriedelin (4 reacted turning into 3-oxo-16-methylfriedel-16-ene (7. This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl3 solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY spectroscopy and mass spectrometry (GC-MS. It is also the first time that all the 13C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.

  11. Qualitative and quantitative control of carbonated cola beverages using ¹H NMR spectroscopy.

    Science.gov (United States)

    Maes, Pauline; Monakhova, Yulia B; Kuballa, Thomas; Reusch, Helmut; Lachenmeier, Dirk W

    2012-03-21

    ¹H Nuclear magnetic resonance (NMR) spectroscopy (400 MHz) was used in the context of food surveillance to develop a reliable analytical tool to differentiate brands of cola beverages and to quantify selected constituents of the soft drinks. The preparation of the samples required only degassing and addition of 0.1% of TSP in D₂O for locking and referencing followed by adjustment of pH to 4.5. The NMR spectra obtained can be considered as "fingerprints" and were analyzed by principal component analysis (PCA). Clusters from colas of the same brand were observed, and significant differences between premium and discount brands were found. The quantification of caffeine, acesulfame-K, aspartame, cyclamate, benzoate, hydroxymethylfurfural (HMF), sulfite ammonia caramel (E 150D), and vanillin was simultaneously possible using external calibration curves and applying TSP as internal standard. Limits of detection for caffeine, aspartame, acesulfame-K, and benzoate were 1.7, 3.5, 0.8, and 1.0 mg/L, respectively. Hence, NMR spectroscopy combined with chemometrics is an efficient tool for simultaneous identification of soft drinks and quantification of selected constituents.

  12. Phenylalanine and tyrosine methyl ester intramolecular interactions and conformational analysis by (1)H NMR and infrared spectroscopies and theoretical calculations.

    Science.gov (United States)

    Cormanich, Rodrigo A; Ducati, Lucas C; Tormena, Cláudio F; Rittner, Roberto

    2014-04-01

    Amino acid conformational analysis in solution are scarce, since these compounds present a bipolar zwitterionic structure ((+)H3NCHRCOO(-)) in these media. Also, intramolecular hydrogen bonds have been classified as the sole interactions governing amino acid conformational behavior in the literature. In the present work we propose phenylalanine and tyrosine methyl ester conformational studies in different solvents by (1)H NMR and infrared spectroscopies and theoretical calculations. Both experimental and theoretical results are in agreement and suggest that the conformational behavior of the phenylalanine and tyrosine methyl esters are similar and are dictated by the interplay between steric and hyperconjugative interactions.

  13. High-resolution (19)F MAS NMR spectroscopy: structural disorder and unusual J couplings in a fluorinated hydroxy-silicate.

    Science.gov (United States)

    Griffin, John M; Yates, Jonathan R; Berry, Andrew J; Wimperis, Stephen; Ashbrook, Sharon E

    2010-11-10

    High-resolution (19)F magic angle spinning (MAS) NMR spectroscopy is used to study disorder and bonding in a crystalline solid. (19)F MAS NMR reveals four distinct F sites in a 50% fluorine-substituted deuterated hydrous magnesium silicate (clinohumite, 4Mg(2)SiO(4)·Mg(OD(1-x)F(x))(2) with x = 0.5), indicating extensive structural disorder. The four (19)F peaks can be assigned using density functional theory (DFT) calculations of NMR parameters for a number of structural models with a range of possible local F environments generated by F(-)/OH(-) substitution. These assignments are supported by two-dimensional (19)F double-quantum MAS NMR experiments that correlate F sites based on either spatial proximity (via dipolar couplings) or through-bond connectivity (via scalar, or J, couplings). The observation of (19)F-(19)F J couplings is unexpected as the fluorines coordinate Mg atoms and the Mg-F interaction is normally considered to be ionic in character (i.e., there is no formal F-Mg-F covalent bonding arrangement). However, DFT calculations predict significant (19)F-(19)F J couplings, and these are in good agreement with the splittings observed in a (19)F J-resolved MAS NMR experiment. The existence of these J couplings is discussed in relation to both the nature of bonding in the solid state and the occurrence of so-called "through-space" (19)F-(19)F J couplings in solution. Finally, we note that we have found similar structural disorder and spin-spin interactions in both synthetic and naturally occurring clinohumite samples.

  14. Effects of varying water adsorption on a Cu3(BTC)2 metal-organic framework (MOF) as studied by 1H and 13C solid-state NMR spectroscopy.

    Science.gov (United States)

    Gul-E-Noor, Farhana; Jee, Bettina; Pöppl, Andreas; Hartmann, Martin; Himsl, Dieter; Bertmer, Marko

    2011-05-07

    The process of water adsorption on a dehydrated Cu(3)(BTC)(2) (copper (II) benzene 1,3,5-tricarboxylate) metal-organic framework (MOF) was studied with (1)H and (13)C solid-state NMR. Different relative amounts of water (0.5, 0.75, 1, 1.5, 2, and 5 mole equivalents with respect to copper) were adsorbed via the gas phase. (1)H and (13)C MAS NMR spectra of dehydrated and water-loaded Cu(3)(BTC)(2) samples gave evidence on the structural changes due to water adsorption within the MOF material as well as information on water dynamics. The analysis of (1)H spinning sideband intensities reveals differences in the (1)H-(63/65)Cu hyperfine coupling between dehydrated and water-loaded samples. The investigation was continued for 60 days to follow the stability of the Cu(3)(BTC)(2) network under humid conditions. NMR data reveal that Cu(3)(BTC)(2) decomposes quite fast with the decomposition being different for different water contents. This journal is © the Owner Societies 2011

  15. Differentiating brown and white adipose tissues by high-resolution diffusion NMR spectroscopy.

    Science.gov (United States)

    Verma, Sanjay Kumar; Nagashima, Kaz; Yaligar, Jadegoud; Michael, Navin; Lee, Swee Shean; Xianfeng, Tian; Gopalan, Venkatesh; Sadananthan, Suresh Anand; Anantharaj, Rengaraj; Velan, S Sendhil

    2017-01-01

    There are two types of fat tissues, white adipose tissue (WAT) and brown adipose tissue (BAT), which essentially perform opposite functions in whole body energy metabolism. There is a large interest in identifying novel biophysical properties of WAT and BAT by a quantitative and easy-to-run technique. In this work, we used high-resolution pulsed field gradient diffusion NMR spectroscopy to study the apparent diffusion coefficient (ADC) of fat molecules in rat BAT and WAT samples. The ADC of fat in BAT and WAT from rats fed with a chow diet was compared with that of rats fed with a high-fat diet to monitor how the diffusion properties change due to obesity-associated parameters such as lipid droplet size, fatty acid chain length, and saturation. Feeding a high-fat diet resulted in increased saturation, increased chain lengths, and reduced ADC of fat in WAT. The ADC of fat was lower in BAT relative to WAT in rats fed both chow and high-fat diets. Diffusion of fat was restricted in BAT due to the presence of small multilocular lipid droplets. Our findings indicate that in vivo diffusion might be a potential way for better delineation of BAT and WAT in both lean and obese states.

  16. Distribution and mobility of phosphates and sodium ions in cheese by solid-state 31P and double-quantum filtered 23Na NMR spectroscopy.

    Science.gov (United States)

    Gobet, Mallory; Rondeau-Mouro, Corinne; Buchin, Solange; Le Quéré, Jean-Luc; Guichard, Elisabeth; Foucat, Loïc; Moreau, Céline

    2010-04-01

    The feasibility of solid-state magic angle spinning (MAS) (31)P nuclear magnetic resonance (NMR) spectroscopy and (23)Na NMR spectroscopy to investigate both phosphates and Na(+) ions distribution in semi-hard cheeses in a non-destructive way was studied. Two semi-hard cheeses of known composition were made with two different salt contents. (31)P Single-pulse excitation and cross-polarization MAS experiments allowed, for the first time, the identification and quantification of soluble and insoluble phosphates in the cheeses. The presence of a relatively 'mobile' fraction of colloidal phosphates was evidenced. The detection by (23)Na single-quantum NMR experiments of all the sodium ions in the cheeses was validated. The presence of a fraction of 'bound' sodium ions was evidenced by (23)Na double-quantum filtered NMR experiments. We demonstrated that NMR is a suitable tool to investigate both phosphates and Na(+) ions distributions in cheeses. The impact of the sodium content on the various phosphorus forms distribution was discussed and results demonstrated that NMR would be an important tool for the cheese industry for the processes controls.

  17. Human in vivo cardiac phosphorus NMR spectroscopy at 3.0 Tesla

    Science.gov (United States)

    Bruner, Angela Properzio

    One of the newest methods with great potential for use in clinical diagnosis of heart disease is human, cardiac, phosphorus NMR spectroscopy (cardiac p 31 MRS). Cardiac p31 MRS is able to provide quantitative, non-invasive, functional information about the myocardial energy metabolites such as pH, phosphocreatine (PCr), and adenosinetriphosphate (ATP). In addition to the use of cardiac p3l MRS for other types of cardiac problems, studies have shown that the ratio of PCr/ATP and pH are sensitive and specific markers of ischemia at the myocardial level. In human studies, typically performed at 1.5 Tesla, PCr/ATP has been relatively easy to measure but often requires long scan times to provide adequate signal-to-noise (SNR). In addition, pH which relies on identification of inorganic phosphate (Pi), has rarely been obtained. Significant improvement in the quality of cardiac p31 MRS was achieved through the use of the General Electric SIGNATM 3.0 Tesla whole body magnet, improved coil designs and optimized pulse sequences. Phantom and human studies performed on many types of imaging and spectroscopy sequences, identified breathhold gradient-echo imaging and oblique DRESS p31 spectroscopy as the best compromises between SNR, flexibility and quality localization. Both single-turn and quadrature 10-cm diameter, p31 radiofrequency coils, were tested with the quadrature coil providing greater SNR, but at a greater depth to avoid skeletal muscle contamination. Cardiac p31 MRS obtained in just 6 to 8 minutes, gated, showed both improved SNR and discernment of Pi allowing for pH measurement. A handgrip, in-magnet exerciser was designed, created and tested at 1.5 and 3.0 Tesla on volunteers and patients. In ischemic patients, this exercise was adequate to cause a repeated drop in PCr/ATP and pH with approximately eight minutes of isometric exercise at 30% maximum effort. As expected from literature, this exercise did not cause a drop in PCr/ATP for reference volunteers.

  18. Interface Induced Growth and Transformation of Polymer-Conjugated Proto-Crystalline Phases in Aluminosilicate Hybrids: A Multiple-Quantum (23)Na-(23)Na MAS NMR Correlation Spectroscopy Study.

    Science.gov (United States)

    Brus, Jiri; Kobera, Libor; Urbanova, Martina; Doušová, Barbora; Lhotka, Miloslav; Koloušek, David; Kotek, Jiří; Čuba, Pavel; Czernek, Jiri; Dědeček, Jiří

    2016-03-22

    Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix. This secondary epoxide phase not only enhances the mechanical integrity of the resulting hybrids but also introduces additional binding sites accessible for compensating negative charge on the aluminosilicate framework. This way, the polymer network initiates growth and subsequent transformation of protocrystalline short-range ordered zeolite domains that are located at the organic-inorganic interface. By applying an experimental approach based on 2D (23)Na-(23)Na double-quantum (DQ) MAS NMR spectroscopy, we discovered multiple sodium binding sites in these protocrystalline domains, in which immobilized Na(+) ions form pairs or small clusters. It is further demonstrated that these sites, the local geometry of which allows for the pairing of sodium ions, are preferentially occupied by Pb(2+) ions during the ion exchange. The proposed synthesis protocol thus allows for the preparation of a novel type of geopolymer hybrids with polymer-conjugated zeolite phases suitable for capturing and storage of metal cations. The demonstrated (23)Na-(23)Na DQ MAS NMR combined with DFT calculations represents a suitable approach for understanding the role of Na(+) ions in aluminositicate solids and related inorganic-organic hybrids, particularly their specific arrangement and clustering at interfacial areas.

  19. Synthesis, spectroscopy (IR, multinuclear NMR, ESI-MS), diffraction, density functional study and in vitro antiproliferative activity of pyrazole-beta-diketone dihalotin(IV) compounds on 5 melanoma cell lines.

    Science.gov (United States)

    Pettinari, Claudio; Caruso, Francesco; Zaffaroni, Nadia; Villa, Raffaella; Marchetti, Fabio; Pettinari, Riccardo; Phillips, Christine; Tanski, Joseph; Rossi, Miriam

    2006-01-01

    Novel 4-acylpyrazolon-5-ato-dihalotin(IV) complexes, [Q2SnX2], (X = F, Cl, Br or I); HQ = HQ(CHPh2) (1,2-dihydro-3-methyl-1-phenyl-4-(2,2-diphenylacetyl)pyrazol-5-one), HQ(Bn) (1,2-dihydro-3-methyl-1-phenyl-4-(2-phenylacetyl)pyrazol-5-one) or HQ(CF3,py) (4-(2,2,2-trifluoroacetyl)-1,2-dihydro-3-methyl-1-(pyridin-2-yl)pyrazol-5-one) have been synthesized and characterized by spectroscopic (IR, 1H, 13C, 19F and 119Sn NMR, electrospray ionisation mass spectrometry (ESI-MS)), analytical and structural methods (X-ray and density functional theory). 119Sn chemical shifts depend on the nature of the halides bonded to tin. Isomer conversion, detected in solution by NMR spectroscopy, is related to the acyl moiety bulkiness while the cis(Cl)-cis(acyl)-trans(pyrazolonato) scheme is found in the solid state. The in vitro antiproliferative tests of three derivatives on three human melanoma cell lines (JR8, SK-MEL-5, MEL501) and two melanoma cell clones (2/21 and 2/60) show dose-dependent decrease of cell proliferation in all cell lines. The activity correlates with the nature of the substituent on position 1 of pyrazole, decreasing in the order pyridyl>Ph>methyl. The activity for (Q(CF3,py))2SnCl2 on the SK-MEL-5 cell line is IC50 = 50 microM.

  20. Refolding of ribonuclease A monitored by real-time photo-CIDNP NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Day, Iain J. [University of Sussex, Department of Chemistry and Biochemistry, School of Life Sciences (United Kingdom); Maeda, Kiminori; Paisley, Howard J. [University of Oxford, Department of Chemistry, Physical and Theoretical Chemistry Laboratory (United Kingdom); Mok, K. Hun [University of Dublin, Trinity College, School of Biochemistry and Immunology (Ireland)], E-mail: mok1@tcd.ie; Hore, P. J. [University of Oxford, Department of Chemistry, Physical and Theoretical Chemistry Laboratory (United Kingdom)], E-mail: peter.hore@chem.ox.ac.uk

    2009-06-15

    Photo-CIDNP NMR spectroscopy is a powerful method for investigating the solvent accessibility of histidine, tyrosine and tryptophan residues in a protein. When coupled to real-time NMR, this technique allows changes in the environments of these residues to be used as a probe of protein folding. In this paper we describe experiments performed to monitor the refolding of ribonuclease A following dilution from a high concentration of chemical denaturant. These experiments provide a good example of the utility of this technique which provides information that is difficult to obtain by other biophysical methods. Real-time photo-CIDNP measurements yield residue-specific kinetic data pertaining to the folding reaction, interpreted in terms of current knowledge of the folding of bovine pancreatic ribonuclease A.

  1. Detoxification of organophosphorus pesticides and nerve agents through RSDL: efficacy evaluation by (31)P NMR spectroscopy.

    Science.gov (United States)

    Elsinghorst, Paul W; Worek, Franz; Koller, Marianne

    2015-03-04

    Intoxication by organophosphorus compounds, especially by pesticides, poses a considerable risk to the affected individual. Countermeasures involve both medical intervention by means of antidotes as well as external decontamination to reduce the risk of dermal absorption. One of the few decontamination options available is Reactive Skin Decontamination Lotion (RSDL), which was originally developed for military use. Here, we present a (31)P NMR spectroscopy based methodology to evaluate the detoxification efficacy of RSDL with respect to a series of organophosphorus pesticides and nerve agents. Kinetic analysis of the obtained NMR data provided degradation half-lives proving that RSDL is also reasonably effective against organophosphorus pesticides. Unexpected observations of different RSDL degradation patterns are presented in view of its reported oximate-catalyzed mechanism of action.

  2. Monitoring adsorption-induced switching by (129)Xe NMR spectroscopy in a new metal-organic framework Ni(2)(2,6-ndc)(2)(dabco).

    Science.gov (United States)

    Klein, Nicole; Herzog, Christin; Sabo, Michal; Senkovska, Irena; Getzschmann, Jürgen; Paasch, Silvia; Lohe, Martin R; Brunner, Eike; Kaskel, Stefan

    2010-10-07

    The synthesis and structure of a new flexible metal-organic framework Ni(2)(2,6-ndc)(2)(dabco) (DUT-8(Ni), DUT = Dresden University of Technology, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane) as well as its characterization by gas adsorption and (129)Xe NMR spectroscopy is described. The compound shows reversible structural transformation without loss of crystallinity upon solvent removal and physisorption of several gases. Xenon adsorption studies combined with (129)Xe NMR spectroscopy turn out to be favorable methods for the detection and characterization of the so-called "gate-pressure" effect in this novel MOF material. The linewidth and chemical shift of the (129)Xe NMR signal are shown to be very sensitive parameters for the detection of this structural transition from a narrow pore system with low porosity to a wide pore state. The transition and threshold temperature is clearly detected.

  3. 口腔癌患者血清核磁共振代谢组学研究%Metabonomic studies of serum obtained from oral cancer patients using 1H NMR spectroscopy

    Institute of Scientific and Technical Information of China (English)

    黄奇骏; 姚婕; 黎玉君; 翁合妹; 龚嘉欣; 丘翠环; 杨永霞

    2013-01-01

    Objective To research the metabolite compositions of the serum samples from oral cancer patients by using nuclear magnetic resonance (NMR) based metabonomics. Methods NMR 1H spectra were measured for serum samples from 10 healthy volunteers and 10 oral cancer patients. The spectra data were analyzed by principal component analysis (PCA) to reveal the metabonomic profiles of serum from oral cancer patients and the corresponding biochemical changes. Results There were obvious metabonomic differences between healthy volunteers and oral cancer patients which were highlighted by the increased levels in amino acids (leucine, isoleucine, valine, tyrosine, phenylalanine, his-tidine), glutamate,glycoprotein, methylamine, dimethylamine and glucose, together with the decreased levels of lactate and choline in oral cancer patients. Conclusion The results show that the metabonome of serum from oral cancer patients differ markedly from that of the healthy volunteers, which indicates that serum NMR 'H spectroscopy in conjunction with PCA offers an efficient tool for the diagnosis of oral cancer.%目的 应用核磁共振代谢组学方法研究口腔癌患者血清代谢组的特征及其变化.方法健康人血清(健康组,10例)和口腔癌患者血清(口腔癌组,10例)样本,采用BRUKER 500 MHz 超导核磁共振波谱仪进行检测,运用PCA分析方法,研究口腔癌患者血清代谢组的特征,探讨相关生化过程的改变.结果健康组与口腔癌组患者血清代谢谱有不同的代谢特征.口腔癌患者血清中氨基酸(亮氨酸、异亮氨酸、缬氨酸、酪氨酸、苯丙氨酸、组氨酸),谷氨酸、糖蛋白、甲胺和二甲胺、葡萄糖的含量是升高的,而乳酸和胆碱的含量降低.结论根据血清代谢物的变化可以区分健康人和口腔癌患者.这种基于核磁共振氢谱的代谢组学方法可为口腔癌的诊断提供可靠代谢依据.

  4. 31P NMR for the study of P metabolism and translocation in arbuscular mycorrhizal fungi

    DEFF Research Database (Denmark)

    Rasmussen, N.; Lloyd, D.C.; Ratcliffe, R.G.

    2000-01-01

    P-31 nuclear magnetic resonance (NMR) spectroscopy was used to study phosphate (P) metabolism in mycorrhizal and nonmycorrhizal roots of cucumber (Cucumis sativus L) and in external mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith. The in vivo NMR method allows...... biological systems to be studied non-invasively and non-destructively. (3)1P NMR experiments provide information about cytoplasmic and vacuolar pH, based on the pH-dependent chemical shifts of the signals arising from the inorganic P (P-i) located in the two compartments. Similarly, the resonances arising...... from alpha, beta and gamma phosphates of nucleoside triphosphates (NTP) and nucleoside diphosphates (NDP) supply knowledge about the metabolic activity and the energetic status of the tissue. In addition, the kinetic behaviour of P uptake and storage can be determined with this method. The (3)1P NMR...

  5. NMR doesn't lie or how solid-state NMR spectroscopy contributed to a better understanding of the nature and function of soil organic matter (Philippe Duchaufour Medal Lecture)

    Science.gov (United States)

    Knicker, Heike

    2016-04-01

    "Nuclear magnetic resonance (NMR) does not lie". More than anything else, this statement of a former colleague and friend has shaped my relation to solid-state NMR spectroscopy. Indeed, if this technique leads to results which contradict the expectations, it is because i) some parts of the instrument are broken, ii) maladjustment of the acquisition parameters or iii) wrong preparation or confusion of samples. However, it may be even simpler, namely that the expectations were wrong. Of course, for researchers, the latter is the most interesting possibility since it forces to reassess accepted views and to search for new explanations. As my major analytical tool, NMR spectroscopy has confronted me with this challenge often enough to turn this issue into the main subject of my talk and to share with the audience how it formed my understanding of function and nature of soil organic matter (SOM). Already shortly after its introduction into soil science in the 1980's, the data obtained with solid-state 13C NMR spectroscopy opened the stage for ongoing discussions, since they showed that in humified SOM aromatic carbon is considerably less important than previously thought. This finding had major implications regarding the understanding of the origin of SOM and the mechanisms by which it is formed. Certainly, the discrepancy between the new results and previous paradigms contributed to mistrust in the reliability of solid-state NMR techniques. The respective discussion has survived up to our days, although already in the 1980's and 1990's fundamental studies could demonstrate that quantitative solid-state NMR data can be obtained if i) correct acquisition parameters are chosen, ii) the impact of paramagnetic compounds is reduced and iii) the presence of soot in soils can be excluded. On the other hand, this mistrust led to a detailed analysis of the impact of paramagnetics on the NMR behavior of C groups which then improved our understanding of the role of carbohydrates

  6. 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.

  7. Microfabricated inserts for magic angle coil spinning (MACS wireless NMR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Vlad Badilita

    Full Text Available This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the "magic angle" of 54.74° with respect to the direction of the magnetic field (magic angle spinning - MAS, accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii given the high spinning rates (tens of kHz involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds.

  8. NMR studies of polysaccharides from brown seaweeds

    Energy Technology Data Exchange (ETDEWEB)

    Noseda, M.D.; Tisher, C.A.; Gorin, P.A.J.; Duarte, M.E.R. [Parana Univ., Curitiba, PR (Brazil). Dept. de Bioquimica; Cerezo, A.S. [Buenos Aires Univ. Nacional (Argentina). Dept. de Quimica Organica

    1997-12-31

    Alginic acid is the major intercellular polysaccharide serving as matrix in the brown algae and is comprised of an unbranched chain of (1->4)-linked {beta}-D-mannuronic acid (M) and {alpha}-L-guluronic acid (G), arranged in a blockwise fashion. The composition of the monomer residues and the block structure varies depending on the source of the polymer. The selective binding of cations to alginate accounts for its ability to form gels, which is dependent on the number and lenght of the G-blocks. They are widely used industrially for their ability to retain water, and for their gelling, viscosifying and stabilizing properties (Smidsrod and draget, 1996). In this study, alginate composition and block structure in Sargassum stenophyllum has been determined by chemical methods and NMR spectroscopic analysis. (author) 4 refs., 3 figs.

  9. Separation of 2H MAS NMR Spectra by Two-Dimensional Spectroscopy

    Science.gov (United States)

    Kristensen, J. H.; Bildsøe, H.; Jakobsen, H. J.; Nielsen, N. C.

    1999-08-01

    New methods for optimum separation of 2H MAS NMR spectra are presented. The approach is based on hypercomplex spectroscopy that is useful for sign discrimination and phase separation. A new theoretical formalism is developed for the description of hypercomplex experiments. This exploits the properties of Lie algebras and hypercomplex numbers to obtain a solution to the Liouville-von Neumann equation. The solution is expressed in terms of coherence transfer functions that describe the allowed coherence transfer pathways in the system. The theoretical formalism is essential in order to understand all the features of hypercomplex experiments. The method is applied to the development of two-dimensional quadrupole-resolved 2H MAS NMR spectroscopy. The important features of this technique are discussed and two different versions are presented with widely different characteristics. An improved version of two-dimensional double-quantum 2H MAS NMR spectroscopy is developed. The conditions under which the double-quantum experiment is useful are discussed and its performance is compared with that observed for the quadrupole-resolved experiments. A general method is presented for evaluating the optimum pulse sequence parameters consistent with maximum sensitivity and resolution. This approach improves the performance of the experiments and is essential for any further development of the techniques. The effects of finite pulse width and hypercomplex data processing may lead to both intensity and phase distortions in the spectra. These effects are analyzed and general correction procedures are suggested. The techniques are applied to polycrystalline malonic-acid-2H4 for which the spinning sideband manifolds from the carboxyl and methylene deuterons are separated. The spinning sideband manifolds are simulated to determine the quadrupole parameters. The values are consistent with previous results, indicating that the techniques are both accurate and reliable.

  10. 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.

  11. NMR study of hydroxy and amide protons in hyaluronan polymers.

    Science.gov (United States)

    Nestor, Gustav; Sandström, Corine

    2017-02-10

    Hyaluronan (HA) is an important and well characterized glycosaminoglycan with high viscosity and water-retaining capacity. Nonetheless, it is not fully understood whether conformational properties of the easily characterized HA oligomers can be transferred to HA polymers. To investigate possible differences in hydration, hydrogen bonding and flexibility between HA polymers and oligomers, hydroxy and amide protons of HA polymers were studied by solution-state and high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Measurements of chemical shifts, temperature coefficients and NOEs in HA polymers revealed that the NMR data are very similar compared to the interior of a HA octasaccharide, supporting transient hydrogen bond interactions across the β(1→3) and β(1→4) glycosidic linkages. However, differences in NOEs suggested a cis-like orientation between NH and H2 in the HA polymer. The lack of concentration dependence of the hydroxy proton chemical shifts suggests that there are no direct inter-chain interactions involving hydroxy protons at the concentrations investigated.

  12. Probing the Pu4 + magnetic moment in PuF4 with 19F NMR spectroscopy

    Science.gov (United States)

    Capan, Cigdem; Dempsey, Richard J.; Sinkov, Sergey; McNamara, Bruce K.; Cho, Herman

    2016-06-01

    The magnetic fields produced by Pu4 + centers have been measured by 19F NMR spectroscopy to elucidate the Pu-F electronic interactions in polycrystalline PuF4. Spectra acquired at applied fields of 2.35 and 7.05 T reveal a linear scaling of the 19F line shape. A model is presented that treats the line broadening and shifts as due to dipolar fields produced by Pu valence electrons in localized noninteracting orbitals. Alternative explanations for the observed line shape involving covalent Pu-F bonding, superexchange interactions, and electronic configurations with enhanced magnetic moments are considered.

  13. Employing NMR Spectroscopy To Evaluate Transmission of Electronic Effects in 4-Substituted Chalcones

    Science.gov (United States)

    Wachter-Jurcsak, Nanette; Zamani, Hossein

    1999-05-01

    Described is an organic synthesis experiment that demonstrates the electronic transmission by substituents. The effect of substitution at the para-position of the styryl ring of 1,3-diphenyl-2-propenones (chalcones) by typical electron-donating or -accepting groups can be observed by proton and carbon-13 NMR spectroscopy. A linear correlation is observed when the differences in chemical shift measurements for H are plotted against the corresponding Hammett substituent constant values. Good correlation between carbon-13 chemical shifts of the alpha carbon are also observed. The syntheses of the 4-substituted chalcones is presented as well as a brief discussion of the theory.

  14. Studies on irradiation stability of polystyrene by NMR

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  15. 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...

  16. 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.

  17. Comparison of Metabolite Concentrations in the Left Dorsolateral Prefrontal Cortex, the Left Frontal White Matter, and the Left Hippocampus in Patients in Stable Schizophrenia Treated with Antipsychotics with or without Antidepressants. 1H-NMR Spectroscopy Study

    Directory of Open Access Journals (Sweden)

    Dominik Strzelecki

    2015-10-01

    Full Text Available Managing affective, negative, and cognitive symptoms remains the most difficult therapeutic problem in stable phase of schizophrenia. Efforts include administration of antidepressants. Drugs effects on brain metabolic parameters can be evaluated by means of proton nuclear magnetic resonance (1H-NMR spectroscopy. We compared spectroscopic parameters in the left prefrontal cortex (DLPFC, the left frontal white matter (WM and the left hippocampus and assessed the relationship between treatment and the spectroscopic parameters in both groups. We recruited 25 patients diagnosed with schizophrenia (DSM-IV-TR, with dominant negative symptoms and in stable clinical condition, who were treated with antipsychotic and antidepressive medication for minimum of three months. A group of 25 patients with schizophrenia, who were taking antipsychotic drugs but not antidepressants, was matched. We compared metabolic parameters (N-acetylaspartate (NAA, myo-inositol (mI, glutamatergic parameters (Glx, choline (Cho, and creatine (Cr between the two groups. All patients were also assessed with the Positive and Negative Syndrome Scale (PANSS and the Calgary Depression Scale for Schizophrenia (CDSS. In patients receiving antidepressants we observed significantly higher NAA/Cr and NAA/Cho ratios within the DLPFC, as well as significantly higher mI/Cr within the frontal WM. Moreover, we noted significantly lower values of parameters associated with the glutamatergic transmission—Glx/Cr and Glx/Cho in the hippocampus. Doses of antipsychotic drugs in the group treated with antidepressants were also significantly lower in the patients showing similar severity of psychopathology.

  18. 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 $\

  19. Redox-dependent conformational changes in eukaryotic cytochromes revealed by paramagnetic NMR spectroscopy.

    Science.gov (United States)

    Volkov, Alexander N; Vanwetswinkel, Sophie; Van de Water, Karen; van Nuland, Nico A J

    2012-03-01

    Cytochrome c (Cc) is a soluble electron carrier protein, transferring reducing equivalents between Cc reductase and Cc oxidase in eukaryotes. In this work, we assessed the structural differences between reduced and oxidized Cc in solution by paramagnetic NMR spectroscopy. First, we have obtained nearly-complete backbone NMR resonance assignments for iso-1-yeast Cc and horse Cc in both oxidation states. These were further used to derive pseudocontact shifts (PCSs) arising from the paramagnetic haem group. Then, an extensive dataset comprising over 450 measured PCSs and high-resolution X-ray and solution NMR structures of both proteins were used to define the anisotropic magnetic susceptibility tensor, Δχ. For most nuclei, the PCSs back-calculated from the Δχ tensor are in excellent agreement with the experimental PCS values. However, several contiguous stretches-clustered around G41, N52, and A81-exhibit large deviations both in yeast and horse Cc. This behaviour is indicative of redox-dependent structural changes, the extent of which is likely conserved in the protein family. We propose that the observed discrepancies arise from the changes in protein dynamics and discuss possible functional implications.

  20. Structural Characterization of Lignins Isolated from Caragana sinica Using FT-IR and NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    XIAOLing-ping; SHIZheng-jun; XUFeng; SUN Run-cang; Amar Kmohanty

    2011-01-01

    In order to efficiently explore and use woody biomass,six lignin fractions were isolated from dewaxed Caragana sinica via successive extraction with organic.solvents and alkaline solutions.The lignin structures were characterized by Fourier transform infrared spectroscopy (FT-IR) and 1D and 2D Nuclear Magnetic Resonance (NMR).FT-IR spectra revealed that the “core” of the lignin structure did not significantly change during the treatment under the conditions given.The results of 1 H and 13C NMR demonstrated that the lignin fraction L2,isolated with 70% ethanol containing 1% NaOH,was mainly composed of β-O-4 ether bonds together with G and S units and trace p-hydroxyphenyl unit.Based on the 2D HSQC NMR spectrum,the ethanol organosolv lignin fraction L1,extracted with 70% ethanol,presents a predominance of β-O-4' arylether linkages (61% of total side chains),and a low abundance of condensed carbon-carbon linked structures (such as β-β',β-1',and β-5') and a lower S/G ratio.Furthermore,a small percentage (ca.9%) of the linkage side chain was found to be acylated at the γ-carbon.

  1. Novel monosaccharide fermentation products in Caldicellulosiruptor saccharolyticus identified using NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Isern, Nancy G.; Xue, Junfeng; Rao, Jaya V.; Cort, John R.; Ahring, Birgitte K.

    2013-04-03

    Profiles of metabolites produced by the thermophilic obligately anaerobic cellulose-degrading Gram-positive bacterium Caldicellulosiruptor saccharolyticus DSM 8903 strain following growth on different monosaccharides (D-glucose, D-mannose, L-arabinose, D-arabinose, D-xylose, L-fucose, and D-fucose) as carbon sources revealed several unexpected fermentation products, suggesting novel metabolic capacities and unexplored metabolic pathways in this organism. Both 1H and 13C nuclear magnetic resonance (NMR) spectroscopy were used to determine intracellular and extracellular metabolite profiles. Metabolite profiles were determined from 1-D 1H NMR spectra by curve fitting against spectral libraries provided in Chenomx software. To reduce uncertainties due to unassigned, overlapping, or poorly-resolved peaks, metabolite identifications were confirmed with 2-D homonuclear and heteronuclear NMR experiments. In addition to expected metabolites such as acetate, lactate, glycerol, and ethanol, several novel fermentation products were identified: ethylene glycol (from growth on D-arabinose, though not L-arabinose), acetoin and 2,3-butanediol (from D-glucose and L-arabinose), and hydroxyacetone (from D-mannose and L-arabinose). Production of ethylene glycol from D-arabinose was particularly notable, with around 10% of the substrate carbon converted into this uncommon fermentation product. The novel products have not previously been reported to be produced by C. saccharolyticus, nor would they be easily predicted from the current genome annotation, and show new potentials for using this strain for production of bioproducts.

  2. Investigation of Oxidative Degradation in Polymers Using (17)O NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd M.; Celina, Mathew; Assink, Roger A.; Clough, Roger L.; Gillen, Kenneth T.; Wheeler David R.

    1999-07-20

    The thermal oxidation of pentacontane (C{sub 50}H{sub 102}), and of the homopolymer polyisoprene, has been investigated using {sup 17}O NMR spectroscopy. By performing the oxidation using {sup 17}O labeled O{sub 2} gas, it is possible to easily identify degradation products, even at relatively low concentrations. It is demonstrated that details of the degradation mechanism can be obtained from analysis of the {sup 17}O NMR spectra as a function of total oxidation. Pentacontane reveals the widest variety of reaction products, and exhibits changes in the relative product distributions with increasing O{sub 2} consumption. At low levels of oxygen incorporation, peroxides are the major oxidation product, while at later stages of degradation these species are replaced by increasing concentrations of ketones, alcohols, carboxylic acids and esters. Analyzing the product distribution can help in identification of the different free-radical decomposition pathways of hydroperoxides, including recombination, proton abstraction and chain scission, as well as secondary reactions. The {sup 17}O NMR spectra of thermally oxidized polyisoprene reveal fewer degradation functionalities, but exhibit an increased complexity in the type of observed degradation species due to structural features such as unsaturation and methyl branching. Alcohols and ethers formed from hydrogen abstraction and free radical termination.

  3. Symmetry Breaking in NMR Spectroscopy: The Elucidation of Hidden Molecular Rearrangement Processes

    Directory of Open Access Journals (Sweden)

    Michael J. McGlinchey

    2014-08-01

    Full Text Available Variable-temperature NMR spectroscopy is probably the most convenient and sensitive technique to monitor changes in molecular structure in solution. Rearrangements that are rapid on the NMR time-scale exhibit simplified spectra, whereby non-equivalent nuclear environments yield time-averaged resonances. At lower temperatures, when the rate of exchange is sufficiently reduced, these degeneracies are split and the underlying “static” molecular symmetry, as seen by X-ray crystallography, becomes apparent. Frequently, however, such rearrangement processes are hidden, even when they become slow on the NMR time-scale, because the molecular point group remains unchanged. Judicious symmetry breaking, such as by substitution of a molecular fragment by a similar, but not identical moiety, or by the incorporation of potentially diastereotopic (chemically non-equivalent nuclei, allows the elucidation of the kinetics and energetics of such processes. Examples are chosen that include a wide range of rotations, migrations and other rearrangements in organic, inorganic and organometallic chemistry.

  4. Methylation patterns of aquatic humic substances determined by 13C NMR spectroscopy

    Science.gov (United States)

    Thorn, K.A.; Steelink, C.; Wershaw, R. L.

    1987-01-01

    13C NMR spectroscopy is used to examine the hydroxyl group functionality of a series of humic and fulvic acids from different aquatic environments. Samples first are methylated with 13C-labeled diazomethane. The NMR spectra of the diazomethylated samples allow one to distinguish between methyl esters of carboxylic acids, methyl ethers of phenolic hydroxyls, and methyl ethers of phenolic hydroxyls adjacent to two substituents. Samples are then permethylated with 13C-labeled methyl iodide/NaH. 13C NMR spectra of permethylated samples show that a significant fraction of the hydroxyl groups is not methylated with diazomethane alone. In these spectra methyl ethers of carbohydrate and aliphatic hydroxyls overlap with methyl ethers of phenolic hydroxyls. Side reactions of the methyltion procedure including carbon methylation in the CH3I/NaH procedure, are also examined. Humic and fulvic acids from bog, swamp, groundwater, and lake waters showssome differences in their distribution of hydroxyl groups, mainly in the concentrations of phenolic hydroxyls, which may be attributed to their different biogeochemical origins. ?? 1987.

  5. Advanced Structural Determination of Diterpene Esters Using Molecular Modeling and NMR Spectroscopy.

    Science.gov (United States)

    Nothias-Scaglia, Louis-Félix; Gallard, Jean-François; Dumontet, Vincent; Roussi, Fanny; Costa, Jean; Iorga, Bogdan I; Paolini, Julien; Litaudon, Marc

    2015-10-23

    Three new jatrophane esters (1-3) were isolated from Euphorbia amygdaloides ssp. semiperfoliata, including an unprecedented macrocyclic jatrophane ester bearing a hemiketal substructure, named jatrohemiketal (3). The chemical structures of compounds 1-3 and their relative configurations were determined by spectroscopic analysis. The absolute configuration of compound 3 was determined unambiguously through an original strategy combining NMR spectroscopy and molecular modeling. Conformational search calculations were performed for the four possible diastereomers 3a-3d differing in their C-6 and C-9 stereocenters, and the lowest energy conformer was used as input structure for geometry optimization. The prediction of NMR parameters ((1)H and (13)C chemical shifts and (1)H-(1)H coupling constants) by density functional theory (DFT) calculations allowed identifying the most plausible diastereomer. Finally, the stereostructure of 3 was solved by comparison of the structural features obtained by molecular modeling for 3a-3d with NMR-derived data (the values of dihedral angles deduced from the vicinal proton-proton coupling constants ((3)JHH) and interproton distances determined by ROESY). The methodology described herein provides an efficient way to solve or confirm structural elucidation of new macrocyclic diterpene esters, in particular when no crystal structure is available.

  6. Mapping protein-protein interaction by {sup 13}C'-detected heteronuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bertini, Ivano, E-mail: ivanobertini@cerm.unifi.it; Felli, Isabella C. [University of Florence, Department of Chemistry (Italy); Gonnelli, Leonardo [University of Florence, Magnetic Resonance Center (CERM) (Italy); Pierattelli, Roberta [University of Florence, Department of Chemistry (Italy); Spyranti, Zinovia; Spyroulias, Georgios A. [University of Patras, Department of Pharmacy (Greece)

    2006-10-15

    The copper-mediated protein-protein interaction between yeast Atx1 and Ccc2 has been examined by protonless heteronuclear NMR and compared with the already available {sup 1}H-{sup 15}N HSQC information. The observed chemical shift variations are analyzed with respect to the actual solution structure, available through intermolecular NOEs. The advantage of using the CON-IPAP spectrum with respect to the {sup 1}H-{sup 15}N HSQC resides in the increased number of signals observed, including those of prolines. CBCACO-IPAP experiments allow us to focus on the interaction region and on side-chain carbonyls, while a newly designed CEN-IPAP experiment on side-chains of lysines. An attempt is made to rationalize the chemical shift variations on the basis of the structural data involving the interface between the proteins and the nearby regions. It is here proposed that protonless{sup 13}C direct-detection NMR is a useful complement to {sup 1}H based NMR spectroscopy for monitoring protein-protein and protein-ligand interactions.

  7. Optimization of identity operation in NMR spectroscopy via genetic algorithm: Application to the TEDOR experiment

    Science.gov (United States)

    Manu, V. S.; Veglia, Gianluigi

    2016-12-01

    Identity operation in the form of π pulses is widely used in NMR spectroscopy. For an isolated single spin system, a sequence of even number of π pulses performs an identity operation, leaving the spin state essentially unaltered. For multi-spin systems, trains of π pulses with appropriate phases and time delays modulate the spin Hamiltonian to perform operations such as decoupling and recoupling. However, experimental imperfections often jeopardize the outcome, leading to severe losses in sensitivity. Here, we demonstrate that a newly designed Genetic Algorithm (GA) is able to optimize a train of π pulses, resulting in a robust identity operation. As proof-of-concept, we optimized the recoupling sequence in the transferred-echo double-resonance (TEDOR) pulse sequence, a key experiment in biological magic angle spinning (MAS) solid-state NMR for measuring multiple carbon-nitrogen distances. The GA modified TEDOR (GMO-TEDOR) experiment with improved recoupling efficiency results in a net gain of sensitivity up to 28% as tested on a uniformly 13C, 15N labeled microcrystalline ubiquitin sample. The robust identity operation achieved via GA paves the way for the optimization of several other pulse sequences used for both solid- and liquid-state NMR used for decoupling, recoupling, and relaxation experiments.

  8. 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.

  9. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

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

  10. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

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

  11. 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

  12. New strategy for stable-isotope-aided, multidimensional NMR spectroscopy of DNA oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Okira; Tate, Shin-Ichi; Kainosho, Masatsune [Tokyo Metropolitan Univ., Tokyo (Japan)

    1994-12-01

    Nuclear Magnetic Resonance (NMR) is the most efficient method for determining the solution structures of biomolecules. By applying multidimensional heteronuclear NMR techniques to {sup 13}C/{sup 15}N-labeled proteins, we can determine the solution structures of proteins with molecular mass of 20 to 30kDa at an accuracy similar to that of x-ray crystallography. Improvements in NMR instrumentation and techniques as well as the development of protein engineering methods for labeling proteins have rapidly advanced multidimensional heteronuclear NMR of proteins. In contrast, multidimensional heteronuclear NMR studies of nucleic acids is less advanced because there were no efficient methods for preparing large amounts of labeled DNA/RNA oligomers. In this report, we focused on the chemical synthesis of DNA oligomers labeled at specific residue(s). RNA oligomers with specific labels, which are difficult to synthesize by the enzyme method, can be synthesized by the chemical method. The specific labels are useful for conformational analysis of larger molecules such as protein-nucleic acid complexes.

  13. [Effect of rehabilitation after myocardial infarction on muscular metabolism. Contribution of phosphorus 31 NMR spectroscopy].

    Science.gov (United States)

    Cottin, Y; Marcer, I; Walker, P; Verges, B; Caillaux, B X; Louis, P; Didier, J P; Casillas, J M; Brunotte, F; Wolf, J E

    1994-06-01

    P 31 NMR spectroscopy is a recent technique which allows a non-invasive and direct analysis of oxidative metabolism and pH changes, an indicator of acidosis due to lactic acid accumulation in the skeletal muscles. The authors investigated oxidative muscular metabolism of the sural triceps in 10 patients after myocardial infarction by performing a study after the acute phase and repeating the study after a programme of physical training. At rest, there were no significant differences. On the other hand, for the same level of maximal effort, the depletion in phosphocreatinine (PCr) and the accumulation of inorganic phosphate (Pi) were significantly lower after physical training: the PCr/PCr + Pi increased from 0.467 +/- 0.179 to 0.538 +/- 0.20 (p < 0.02) and the Pi/PCr ratio decreased from 1.570 +/- 1.440 to 1.181 +/- 1.069 (p < 0.05). The pH at the same level of maximal exercise did not change significantly between the two periods: 6.85 +/- 0.16 vs 6.88 +/- 0.15 (NS). The peak oxygen consumption (VO2) measured during bicycle ergometry increased significantly from 23.4 +/- 10.5 to 28.3 +/- 12.14 ml/min/kg after exercise training (p < 0.01). In addition, a correlation was observed between the improvement of the peripheral parameters (PCr/PCr + Pi) and the increase in VO2 max (r = 0.757, p < 0.01). The authors results confirm the effects of physical training on oxidative metabolisms of the peripheral muscles and its influence on improvement of global performance of coronary patients.

  14. Measuring {sup 13}C{sup {beta}} chemical shifts of invisible excited states in proteins by relaxation dispersion NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lundstroem, Patrik [Linkoeping University, Molecular Biotechnology/IFM (Sweden); Lin Hong [Hospital for Sick Children, Molecular Structure and Function (Canada); Kay, Lewis E. [University of Toronto, Department of Medical Genetics (Canada)], E-mail: kay@pound.med.utoronto.ca

    2009-07-15

    A labeling scheme is introduced that facilitates the measurement of accurate {sup 13}C{sup {beta}} 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 {sup 13}C enrichment (30-40%) at C{sup {beta}} side-chain carbon positions for 15 of the amino acids with little {sup 13}C label at positions one bond removed ({approx}5%). A pair of samples are produced using [1-{sup 13}C]-glucose/NaH{sup 12}CO{sub 3} or [2-{sup 13}C]-glucose as carbon sources with isolated and enriched (>30%) {sup 13}C{sup {beta}} 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 {sup 13}C{sup {beta}} 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.

  15. Identification of Imitation Cheese and Imitation Ice Cream Based on Vegetable Fat Using NMR Spectroscopy and Chemometrics

    Directory of Open Access Journals (Sweden)

    Yulia B. Monakhova

    2013-01-01

    Full Text Available Vegetable oils and fats may be used as cheap substitutes for milk fat to manufacture imitation cheese or imitation ice cream. In this study, 400 MHz nuclear magnetic resonance (NMR spectroscopy of the fat fraction of the products was used in the context of food surveillance to validate the labeling of milk-based products. For sample preparation, the fat was extracted using an automated Weibull-Stoldt methodology. Using principal component analysis (PCA, imitation products can be easily detected. In both cheese and ice cream, a differentiation according to the type of raw material (milk fat and vegetable fat was possible. The loadings plot shows that imitation products were distinguishable by differences in their fatty acid ratios. Furthermore, a differentiation of several types of cheese (Edamer, Gouda, Emmentaler, and Feta was possible. Quantitative data regarding the composition of the investigated products can also be predicted from the same spectra using partial least squares (PLS regression. The models obtained for 13 compounds in cheese (R2 0.75–0.95 and 17 compounds in ice cream (R2 0.83–0.99 (e.g., fatty acids and esters were suitable for a screening analysis. NMR spectroscopy was judged as suitable for the routine analysis of dairy products based on milk or on vegetable fat substitutes.

  16. Identification of Imitation Cheese and Imitation Ice Cream Based on Vegetable Fat Using NMR Spectroscopy and Chemometrics.

    Science.gov (United States)

    Monakhova, Yulia B; Godelmann, Rolf; Andlauer, Claudia; Kuballa, Thomas; Lachenmeier, Dirk W

    2013-01-01

    Vegetable oils and fats may be used as cheap substitutes for milk fat to manufacture imitation cheese or imitation ice cream. In this study, 400 MHz nuclear magnetic resonance (NMR) spectroscopy of the fat fraction of the products was used in the context of food surveillance to validate the labeling of milk-based products. For sample preparation, the fat was extracted using an automated Weibull-Stoldt methodology. Using principal component analysis (PCA), imitation products can be easily detected. In both cheese and ice cream, a differentiation according to the type of raw material (milk fat and vegetable fat) was possible. The loadings plot shows that imitation products were distinguishable by differences in their fatty acid ratios. Furthermore, a differentiation of several types of cheese (Edamer, Gouda, Emmentaler, and Feta) was possible. Quantitative data regarding the composition of the investigated products can also be predicted from the same spectra using partial least squares (PLS) regression. The models obtained for 13 compounds in cheese (R (2) 0.75-0.95) and 17 compounds in ice cream (R (2) 0.83-0.99) (e.g., fatty acids and esters) were suitable for a screening analysis. NMR spectroscopy was judged as suitable for the routine analysis of dairy products based on milk or on vegetable fat substitutes.

  17. Identification of Imitation Cheese and Imitation Ice Cream Based on Vegetable Fat Using NMR Spectroscopy and Chemometrics

    Science.gov (United States)

    Monakhova, Yulia B.; Godelmann, Rolf; Andlauer, Claudia; Kuballa, Thomas; Lachenmeier, Dirk W.

    2013-01-01

    Vegetable oils and fats may be used as cheap substitutes for milk fat to manufacture imitation cheese or imitation ice cream. In this study, 400 MHz nuclear magnetic resonance (NMR) spectroscopy of the fat fraction of the products was used in the context of food surveillance to validate the labeling of milk-based products. For sample preparation, the fat was extracted using an automated Weibull-Stoldt methodology. Using principal component analysis (PCA), imitation products can be easily detected. In both cheese and ice cream, a differentiation according to the type of raw material (milk fat and vegetable fat) was possible. The loadings plot shows that imitation products were distinguishable by differences in their fatty acid ratios. Furthermore, a differentiation of several types of cheese (Edamer, Gouda, Emmentaler, and Feta) was possible. Quantitative data regarding the composition of the investigated products can also be predicted from the same spectra using partial least squares (PLS) regression. The models obtained for 13 compounds in cheese (R 2 0.75–0.95) and 17 compounds in ice cream (R 2 0.83–0.99) (e.g., fatty acids and esters) were suitable for a screening analysis. NMR spectroscopy was judged as suitable for the routine analysis of dairy products based on milk or on vegetable fat substitutes. PMID:26904597

  18. Characterization of pyrogenic organic matter by 2-dimenstional HETeronucleus CORelation solid-state 13C NMR (HETCOR) spectroscopy

    Science.gov (United States)

    Knicker, Heike

    2016-04-01

    During the last years, increasing evidences are provided that the common view of charcoal as a polyaromatic network is too much simplified. Experiments with model compounds indicated that it represents a heterogeneous mixture of thermally altered biomacromolecules with N, O and likely also S substitutions as common features. If produced from a N-rich feedstock, the so called black nitrogen (BN) has to be considered as an integral part of the aromatic charcoal network. In order to study this network one-dimensional (1D) solid-state nuclear magnetic resonance (NMR) spectroscopy is often applied. However, this technique suffers from broad resonance lines and low resolution. Applying 2D techniques can help but until recently, this was unfeasible for natural organic matter (NOM) due to sensitivity problems and the high complexity of the material. On the other hand, during the last decade, the development of stronger magnetic field instruments and advanced pulse sequences has put them into reach for NOM research. Although 2D NMR spectroscopy has many different applications, all pulse sequences are based on the introduction of a preparation time during which the magnetization of a spin system is adjusted into a state appropriate to whatever properties are to be detected in the indirect dimension. Then, the spins are allowed to evolve with the given conditions and after their additional manipulation during a mixing period the modulated magnetization is detected. Assembling several 1D spectra with incrementing evolution time creates a data set which is two-dimensional in time (t1, t2). Fourier transformation of both dimensions leads to a 2D contour plot correlating the interactions detected in the indirect dimension t1 with the signals detected in the direct dimension t2. The so called solid-state heteronuclear correlation (HETCOR) NMR spectroscopy represents a 2D technique allows the determination which protons are interacting with which carbons. In the present work this

  19. Improved compositional analysis of block copolymers using diffusion ordered NMR spectroscopy.

    Science.gov (United States)

    Viel, Stéphane; Mazarin, Michaël; Giordanengo, Rémi; Phan, Trang N T; Charles, Laurence; Caldarelli, Stefano; Bertin, Denis

    2009-11-03

    Block copolymers constitute a fascinating class of polymeric materials that are used in a broad range of applications. The performance of these materials is highly coupled to the physical and chemical properties of the constituting block copolymers. Traditionally, the composition of block copolymers is obtained by 1H NMR spectroscopy on purified copolymer fractions. Specifically, the integrals of a properly selected set of 1H resonances are compared and used to infer the number average molecular weight (M(n)) of one of the block from the (typically known) M(n) value of the other. As a corollary, compositional determinations achieved on imperfectly purified samples lead to serious errors, especially when isolation of the block copolymer from the initial macro initiator is tedious. This investigation shows that Diffusion Ordered NMR Spectroscopy (DOSY) can be used to provide a way to assess the advancement degree of the copolymerization purification/reaction, in order to optimize it and hence contribute to an improved compositional analysis of the resulting copolymer. To this purpose, a series of amphiphilic polystyrene-b-poly(ethylene oxide) block copolymers, obtained by controlled free-radical nitroxide mediated polymerization, were analyzed and it is shown that, under proper experimental conditions, DOSY allows for an improved compositional analysis of these block copolymers.

  20. Identification and quantitative determination of lignans in Cedrus atlantica resins using 13C NMR spectroscopy.

    Science.gov (United States)

    Nam, Anne-Marie; Paoli, Mathieu; Castola, Vincent; Casanova, Joseph; Bighelli, Ange

    2011-03-01

    Identification and quantitative determination of individual components of resin collected on the trunk of 28 Cedrus atlantica trees, grown in Corsica, has been carried out using 13C NMR spectroscopy. Eight resin acids bearing either the pimarane or abietane skeleton, two monoterpene hydrocarbons and four oxygenated neutral diterpenes have been identified, as well as three lignans, scarcely found in resins. Three groups could be distinguished within the 28 resin samples. The nine samples of Group I had their composition dominated by diterpene acids (33.7-45.8%), with abietic acid (6.2-18.7%) and isopimaric acid (5.1-12.6%) being the major components. The four samples of Group II contained resin acids (main components) and lignans in moderate amounts (up to 10.3%). Conversely, lignans (38.8-63.8%) were by far the major components of the 15 samples of Group III. Depending on the sample, the major component was pinoresinol (18.1-38.9%), lariciresinol (17.2-33.7%) or lariciresinol 9'-acetate (16.9-29.1%). Finally, due to the high biological interest in lignans, a rapid procedure, based on 1H NMR spectroscopy, was developed for quantification of lignans in resins of C. atlantica.

  1. A multinuclear static NMR study of geopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  2. Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies

    Science.gov (United States)

    Schenck, Heather L.; Hui, KaWai

    2011-01-01

    These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). The…

  3. Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies

    Science.gov (United States)

    Schenck, Heather L.; Hui, KaWai

    2011-01-01

    These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). The…

  4. New Insights into High-Performance Thermoelectric Tellurides from ^125Te NMR Spectroscopy

    Science.gov (United States)

    Levin, E. M.; Hu, Y.-Y.; Cook, B. A.; Harringa, J. L.; Schmidt-Rohr, K.; Kanatzidis, M. G.

    2009-11-01

    Thermoelectric materials are widely used for direct transformation of heat to electricity (Seebeck effect) and for solid state refrigeration (Peltier effect). Efforts to increase the efficiency of high-performance thermoelectrics, which include narrow-gap, doped tellurium-based semiconductors, require detailed knowledge of their local structure and bonding. We have used ^125Te nuclear magnetic resonance (NMR) as a local probe for obtaining better understanding of these high-performance thermoelectric tellurides, specifically PbTe doped with Ag and Sb (LAST materials) and GeTe doped with Ag and Sb (TAGS materials). The resonance frequencies and line shapes of the NMR spectra, as well as spin-lattice relaxation times and chemical shift anisotropies are highly sensitive to the composition and synthesis conditions of LAST and TAGS materials, enabling studies of the local composition, distortion, bonding, and carrier concentration. Several intriguing phenomena including electronic inhomogeneity and local distortions of the crystal lattice have been observed by NMR.

  5. Two-dimensional NMR exchange spectroscopy. Quantitative treatment of multisite exchanging systems

    Science.gov (United States)

    Abel, Edward W.; Coston, Timothy P. J.; Orrell, Keith G.; Šik, Vladimir; Stephenson, David

    A general method for evaluating rate constants in complex exchange networks with N-sites from two-dimensional EXSY (NOESY) NMR spectra is proposed. A computer program D2DNMR capable of performing signal intensity to exchange rate calculations (and vice versa), based on a matrix formalism, is outlined. The method is illustrated by 195Pt 2D NMR studies of the A ⇌ B ⇌ C spin system arising from pyramidal sulfur inversion in platinum(IV) complexes of type [Pt XMe 3(MeSCH 2CH 2SMe)] ( X = Cl, I). Comparison with 1H NMR bandshape analyses of the same compounds shows high agreement between the rate constants and activation parameters determined by both techniques. Mechanisms of 195Pt spin-lattice relaxation are briefly discussed.

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  8. Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Macduff O. Okuom

    2013-01-01

    Full Text Available DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB, and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1 and the analyte (caffeine that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed.

  9. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang; Feng; Wu; Chengtai; 等

    2003-01-01

    The NMR methods (including 1H NMR, variable temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  10. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang Feng; Wu Xiao-jun; Wu Cheng-tai

    2003-01-01

    The NMR methods (including 1H NMR, vari-able temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  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. Dynamic NMR study of dinitrophenyl derivatives of seven-membered cyclic ketals of pyridoxine.

    Science.gov (United States)

    Rakhmatullin, Ilfat Z; Galiullina, Leisan F; Garipov, Marsel' R; Strel'nik, Alexey D; Shtyrlin, Yurii G; Klochkov, Vladimir V

    2015-10-01

    Two pyridoxine derivatives containing a dinitrophenyl moiety were investigated by (1)H NMR spectroscopy. Conformational dynamics in solution were studied for each compound using dynamic NMR experiments. It was shown that both compounds studied are involved into two conformational exchange processes. The first process is a transformation of the seven-membered cycle conformation between the enantiomeric P-twist and M-twist forms, and the second is a rotation of the dinitrophenyl fragment of the molecules around the C-O bond. Energy barriers of both conformational transitions were determined.

  13. Hydrogen bonding and stacking pi-pi interactions in solid 6-thioguanine and 6-mercaptopurine (antileukemia and antineoplastic drugs) studied by NMR-NQR double resonance spectroscopy and density functional theory.

    Science.gov (United States)

    Latosińska, J N; Seliger, J; Zagar, V; Burchardt, D V

    2009-07-30

    A chemotherapeutic drug 6-thioguanine (2-amino-1,7-dihydro-6H-purine-6-thione, 6-TG) has been studied experimentally in the solid state by NMR-NQR double resonance and theoretically by the density functional theory. Fourteen resonance frequencies on (14)N have been detected and assigned to particular nitrogen sites in the 6-TG molecule. A valid assignment of NQR frequencies for 6-mercaptopurine (6-MP) has been proposed. The effects of molecular aggregations, related to intermolecular hydrogen bonding and stacking pi-pi interactions on the NQR parameters have been analyzed within the DFT and AIM (atoms in molecules) formalism for 6-TG and 6-mercaptopurine (6-MP). The so-called global reactivity descriptors have been calculated to compare the properties of molecules of 6-TG and 6-MP, to check the effect of -NH(2) group as well as to identify the differences in crystal packing.

  14. 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.

  15. Comprehensive multiphase NMR spectroscopy: Basic experimental approaches to differentiate phases in heterogeneous samples

    Science.gov (United States)

    Courtier-Murias, Denis; Farooq, Hashim; Masoom, Hussain; Botana, Adolfo; Soong, Ronald; Longstaffe, James G.; Simpson, Myrna J.; Maas, Werner E.; Fey, Michael; Andrew, Brian; Struppe, Jochem; Hutchins, Howard; Krishnamurthy, Sridevi; Kumar, Rajeev; Monette, Martine; Stronks, Henry J.; Hume, Alan; Simpson, André J.

    2012-04-01

    Heterogeneous samples, such as soils, sediments, plants, tissues, foods and organisms, often contain liquid-, gel- and solid-like phases and it is the synergism between these phases that determine their environmental and biological properties. Studying each phase separately can perturb the sample, removing important structural information such as chemical interactions at the gel-solid interface, kinetics across boundaries and conformation in the natural state. In order to overcome these limitations a Comprehensive Multiphase-Nuclear Magnetic Resonance (CMP-NMR) probe has been developed, and is introduced here, that permits all bonds in all phases to be studied and differentiated in whole unaltered natural samples. The CMP-NMR probe is built with high power circuitry, Magic Angle Spinning (MAS), is fitted with a lock channel, pulse field gradients, and is fully susceptibility matched. Consequently, this novel NMR probe has to cover all HR-MAS aspects without compromising power handling to permit the full range of solution-, gel- and solid-state experiments available today. Using this technology, both structures and interactions can be studied independently in each phase as well as transfer/interactions between phases within a heterogeneous sample. This paper outlines some basic experimental approaches using a model heterogeneous multiphase sample containing liquid-, gel- and solid-like components in water, yielding separate 1H and 13C spectra for the different phases. In addition, 19F performance is also addressed. To illustrate the capability of 19F NMR soil samples, containing two different contaminants, are used, demonstrating a preliminary, but real-world application of this technology. This novel NMR approach possesses a great potential for the in situ study of natural samples in their native state.

  16. NMR ANALYSIS OF MALE FATHEAD MINNOW URINARY METABOLITES: A POTENTIAL APPROACH FOR STUDYING IMPACTS OF CHEMICAL EXPOSURES

    Science.gov (United States)

    The potential for profiling endogenous metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one dimensional (1D) and two dimensional (2D) NMR spectroscopy w...

  17. Solution NMR studies on Helicobacter pylori proteins for antibiotic target discovery.

    Science.gov (United States)

    Lee, Ki-Young; Lee, Bong-Jin

    2016-07-01

    Helicobacter pylori (H. pylori) is a well-known widespread pathogenic bacterium that survives in the extremely acidic conditions of the human gastric mucosa. The global prevalence of H. pylori-resistant antibiotics has become an emerging issue in the 21st century and has necessitated the development of novel antibiotic drugs. Many efforts have aimed to discover antibiotic target proteins of H. pylori based on its genome of more than 1600 genes. This article highlights NMR spectroscopy as a valuable tool for determining the structure and dynamics of potential antibiotic-targeted proteins of H. pylori and evaluating their modes of interaction with native or synthetic binding partners. The residue-specific information on binding in solution provides a structural basis to identify and optimize lead compounds. NMR spectroscopy is a powerful method for obtaining details of biomolecular interactions with a broad range of binding affinities. This strength facilitates the identification of the binding interface of the encounter complex that plays an integral role in a variety of biological functions. This low-affinity complex is difficult to crystallize, which impedes structure determination using X-ray crystallography. Additionally, the relative binding affinities can be predicted from the type of spectral change upon binding. High-resolution NMR spectroscopy in combination with advanced computer simulation would provide more confidence in complex structures. The application of NMR to studies of the H. pylori protein could contribute to the development of these targeted novel antibiotics.

  18. Quantification of lignin-carbohydrate linkages with high-resolution NMR spectroscopy.

    Science.gov (United States)

    Balakshin, Mikhail; Capanema, Ewellyn; Gracz, Hanna; Chang, Hou-min; Jameel, Hasan

    2011-06-01

    A quantitative approach to characterize lignin-carbohydrate complex (LCC) linkages using a combination of quantitative ¹³C NMR and HSQC 2D NMR techniques has been developed. Crude milled wood lignin (MWLc), LCC extracted from MWLc with acetic acid (LCC-AcOH) and cellulolytic enzyme lignin (CEL) preparations were isolated from loblolly pine (Pinus taeda) and white birch (Betula pendula) woods and characterized using this methodology on a routine 300 MHz NMR spectrometer and on a 950 MHz spectrometer equipped with a cryogenic probe. Structural variations in the pine and birch LCC preparations of different types (MWL, CEL and LCC-AcOH) were elucidated. The use of the high field NMR spectrometer equipped with the cryogenic probe resulted in a remarkable improvement in the resolution of the LCC signals and, therefore, is of primary importance for an accurate quantification of LCC linkages. The preparations investigated showed the presence of different amounts of benzyl ether, γ-ester and phenyl glycoside LCC bonds. Benzyl ester moieties were not detected. Pine LCC-AcOH and birch MWLc preparations were preferable for the analysis of phenyl glycoside and ester LCC linkages in pine and birch, correspondingly, whereas CEL preparations were the best to study benzyl ether LCC structures. The data obtained indicate that pinewood contains higher amounts of benzyl ether LCC linkages, but lower amounts of phenyl glycoside and γ-ester LCC moieties as compared to birch wood.

  19. In situ NMR spectroscopy of supercapacitors: insight into the charge storage mechanism.

    Science.gov (United States)

    Wang, Hao; Forse, Alexander C; Griffin, John M; Trease, Nicole M; Trognko, Lorie; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P

    2013-12-18

    Electrochemical capacitors, commonly known as supercapacitors, are important energy storage devices with high power capabilities and long cycle lives. Here we report the development and application of in situ nuclear magnetic resonance (NMR) methodologies to study changes at the electrode-electrolyte interface in working devices as they charge and discharge. For a supercapacitor comprising activated carbon electrodes and an organic electrolyte, NMR experiments carried out at different charge states allow quantification of the number of charge storing species and show that there are at least two distinct charge storage regimes. At cell voltages below 0.75 V, electrolyte anions are increasingly desorbed from the carbon micropores at the negative electrode, while at the positive electrode there is little change in the number of anions that are adsorbed as the voltage is increased. However, above a cell voltage of 0.75 V, dramatic increases in the amount of adsorbed anions in the positive electrode are observed while anions continue to be desorbed at the negative electrode. NMR experiments with simultaneous cyclic voltammetry show that supercapacitor charging causes marked changes to the local environments of charge storing species, with periodic changes of their chemical shift observed. NMR calculations on a model carbon fragment show that the addition and removal of electrons from a delocalized system should lead to considerable increases in the nucleus-independent chemical shift of nearby species, in agreement with our experimental observations.

  20. A simple mathematical model and practical approach for evaluating citric acid cycle fluxes in perfused rat hearts by 13C-NMR and 1H-NMR spectroscopy.

    Science.gov (United States)

    Tran-Dinh, S; Hoerter, J A; Mateo, P; Bouet, F; Herve, M

    1997-04-15

    We propose a simple mathematical model and a practical approach for evaluating the flux constant and the absolute value of flux in the citric acid cycle in perfused organs by 13C-NMR and 1H-NMR spectroscopy. We demonstrate that 13C-NMR glutamate spectra are independent of the relative sizes of the mitochondrial and cytosolic compartments and the exchange rates of glutamates, unless there is a difference in 13C chemical shifts of glutamate carbons between the two compartments. Wistar rat hearts (five beating and four KCl-arrested hearts) were aerobically perfused with 100% enriched [2-(13)C]acetate and the kinetics of glutamate carbon labeling from perchloric acid extracts were studied at various perfusion times. Under our experimental conditions, the citric acid cycle flux constant, which represents the fraction of glutamate in exchange with the citric acid cycle per unit time, is about 0.350 +/- 0.003 min(-1) for beating hearts and 0.0741 +/- 0.004 min(-1) for KCl-arrested hearts. The absolute values of the citric acid flux for beating hearts and for KCl-arrested hearts are 1.06 +/- 0.06 micromol x min(-1) x mg(-1) and 0.21 +/- 0.02 micromol x min(-1) x g(-1), respectively. The fraction of unlabeled acetate determined from the proton signal of the methyl group is small and essentially the same in beating and arrested hearts (7.4 +/- 1.7% and 8.8 +/- 2.1%, respectively). Thus, the large difference in the Glu C2/C4 between beating and arrested hearts is not due to the important contribution from anaplerotic sources in arrested hearts but simply to a substantial difference in citric acid cycle fluxes. Our model fits the experimental data well, indicating a fast exchange between 2-oxoglutarate and glutamate in the mitochondria of rat hearts. Analysis of the flux constant, calculated from the half-time of glutamate C4 labeling given in the literature, allows for a comparison of the citric acid flux for various working conditions in different animal species.

  1. Nuclear magnetic resonance spectroscopy. Status and perspectives of in-vivo NMR spectroscopy as a medical diagnostic technique. Kernresonanzspektroskopie. Stand und Perspektiven der in-vivo-NMR-Spektroskopie in der medizinischen Diagnostik

    Energy Technology Data Exchange (ETDEWEB)

    Rueterjans, H.

    1987-01-01

    Contributions by various authors who are working in the field of NMR imaging present the current status and the perspectives of in-vivo nuclear magnetic resonance spectroscopy, explaining not only the scientific and medical aspects, but also technical and physical principles as well as questions concerning practical organisation and training, and points of main interest for further research activities. (orig./TRV).

  2. Propionate metabolism in the rat heart by 13C n.m.r. spectroscopy.

    Science.gov (United States)

    Sherry, A D; Malloy, C R; Roby, R E; Rajagopal, A; Jeffrey, F M

    1988-01-01

    High-resolution 13C n.m.r. spectroscopy has been used to examine propionate metabolism in the perfused rat heart. A number of tricarboxylic acid (TCA) cycle intermediates are observable by 13C n.m.r. in hearts perfused with mixtures of pyruvate and propionate. When the enriched 13C-labelled nucleus originates with pyruvate, the resonances of the intermediates appear as multiplets due to formation of multiply-enriched 13C-labelled isotopomers, whereas when the 13C-labelled nucleus originates with propionate, these same intermediates appear as singlets in the 13C spectrum since entry of propionate into the TCA cycle occurs via succinyl-CoA. An analysis of the isotopomer populations in hearts perfused with [3-13C]pyruvate plus unlabelled propionate indicates that about 27% of the total pyruvate pool available to the heart is derived directly from unlabelled propionate. This was substantiated by perfusing a heart for 2 h with [3-13C]propionate as the only available exogenous substrate. Under these conditions, all of the propionate consumed by the heart, as measured by conventional chemical analysis, ultimately entered the oxidative pathway as [2-13C] or [3-13C]pyruvate. This is consistent with entry of propionate into the TCA cycle intermediate pools as succinyl-CoA and concomitant disposal of malate to pyruvate via the malic enzyme. 13C resonances arising from enriched methylmalonate and propionylcarnitine are also detected in hearts perfused with [3-13C] or [1-13C]propionate which suggests that 13C n.m.r. may be useful as a non-invasive probe in vivo of metabolic abnormalities involving the propionate pathway, such as methylmalonic aciduria or propionic acidaemia. PMID:3178775

  3. Fast screening of turkish olive oil by NMR spectroscopy for geographical determination and discrimination purposes

    Directory of Open Access Journals (Sweden)

    Ok, S.

    2014-06-01

    Full Text Available The main goal of this study is to rapidly screen olive oil contents by acquiring one dimensional (1D 1H NMR spectra of 38 samples from Turkey, The Middle East, and Libya. The quantitative analysis of the 1H NMR helped in distinguishing the geographical origin of the olive oil samples. The intensity of 1H NMR variables was submitted to the statistical method, analysis of variance (ANOVA. As a result of combining the NMR data and ANOVA, olive oils were discriminated based on regional origin rather than province. This less time consuming discriminative screening by 1H NMR does not require any further analysis of the olive oil, including oxidative stability measurements or gas chromatography. The possibility of determining authenticity, even in an olive growing area of a small village was also shown. The two-dimensional (2D non-invasive 1H DOSY NMR experiment, known as “NMR chromatography”, was used to determine the olive oil sub-fraction.El objetivo es conocer de manera rápida el contenido de aceite de oliva mediante la adquisición de espectros de 1H RMN de una dimensión (1D. El estudio se ha realizado con 38 muestras procedentes de Turquía, Oriente Medio y Libia. El análisis cuantitativo de 1H RMN ayudó a distinguir el origen geográfico de las muestras de aceites de oliva. La intensidad de las señales de 1H RMN se sometió a estudio estadístico mediante análisis de varianza (ANOVA. Como resultado de la combinación de los datos de RMN y ANOVA, los aceites de oliva fueron discriminados por origen regional antes que por provincia. Esta técnica de discriminación rápida por 1H RMN no requiere ningún análisis adicional de los aceites de oliva mediante estudios de estabilidad a la oxidación o cromatografía de gases. También se demostró la posibilidad de determinar la autenticidad, incluso en el área de cultivo del olivo de una pequeña aldea. Los experimentos de RMN bi-dimensionales (2D no invasiva 1H DOSY, conocido como

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

    NARCIS (Netherlands)

    Mierlo, van C.

    1990-01-01

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

  5. Rapid determination of coenzyme Q10 in food supplements using 1H NMR spectroscopy.

    Science.gov (United States)

    Monakhova, Yulia B; Ruge, Ingrid; Kuballa, Thomas; Lerch, Christiane; Lachenmeier, Dirk W

    2013-01-01

    A methodology utilizing 1H NMR spectroscopy has been developed to measure the concentration of coenzyme Q10 (CoQ10) in dietary supplements. For sample preparation, a very simple dilution with deuterated chloroform and addition of internal standard is sufficient. CoQ10 produces a distinct peak of the CH groups in the isoprene side chain of the molecule in the δ 5.15 - 5.05 ppm range, where it can be distinguished from other matrix compounds. The method was shown to be of adequate sensitivity with a limit of detection (LOD) of 7.8 mg/L, to control the CoQ10 content in the majority of the products. The precision expressed as relative standard deviation was around 5 %; linearity was observed from 14 to 2000 mg/L (R = 0.99). The developed methodology was applied for the analysis of 21 food supplements (capsules, tablets, and liquid products). On the basis of the labeled amounts, only two products contained substantially lower concentrations of CoQ10 (57 % and 51 %). All other concentrations varied between 83 % and 190 % with respect to labeling. The developed NMR method may be used by quality assurance laboratories for routine control of CoQ10 products.

  6. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    Science.gov (United States)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  7. Characterization of alkyl carbon in forest soils by CPMAS 13C NMR spectroscopy and dipolar dephasing

    Science.gov (United States)

    Kogel-Knabner, I.; Hatcher, P.G.

    1989-01-01

    Samples obtained from forest soils at different stages of decomposition were treated sequentially with chloroform/methanol (extraction of lipids), sulfuric acid (hydrolysis), and sodium chlorite (delignification) to enrich them in refractory alkyl carbon. As revealed by NMR spectroscopy, this treatment yielded residues with high contents of alkyl carbon. In the NMR spectra of residues obtained from litter samples, resonances for carbohydrates are also present, indicating that these carbohydrates are tightly bound to the alkyl carbon structures. During decomposition in the soils this resistant carbohydrate fraction is lost almost completely. In the litter samples the alkyl carbon shows a dipolar dephasing behavior indicative of two structural components, a rigid and a more mobile component. As depth and decomposition increase, only the rigid component is observed. This fact could be due to selective degradation of the mobile component or to changes in molecular mobility during decomposition, e.g., because of an increase in cross linking or contact with the mineral matter of the soil.

  8. Microstructure determination of 2-hydroxy ethyl methacrylate and methyl acrylate copolymers by NMR spectroscopy

    Science.gov (United States)

    Brar, A. S.; Hooda, Sunita; Goyal, Ashok Kumar

    2007-02-01

    Copolymers of 2-Hydroxy ethyl methacrylate and methyl acrylate (H/M) of different compositions were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator under nitrogen atmosphere. The copolymers compositions were calculated from 1H NMR spectra. The reactivity ratios for H/M copolymers obtained from a linear Kelen-Tudos method (KT) and nonlinear error-in-variables method (EVM) are rH = 3.31 ± 0.08, rM = 0.23 ± 0.00 and rH = 3.32, rM = 0.23, respectively. The complete spectral assignment of methine, methylene, methyl and carbonyl carbon regions in terms of compositional and configurational sequences of H/M copolymers was done with the help of 13C{ 1H} NMR, distortionless enhancement by polarization transfer (DEPT), two-dimensional heteronuclear single quantum coherence (HSQC) along with total correlated spectroscopy (TOCSY). Further, the assignments of carbonyl region were made with the help of heteronuclear multiple bond coherence (HMBC) spectrum.

  9. Time-domain Bayesian detection and estimation of noisy damped sinusoidal signals applied to NMR spectroscopy.

    Science.gov (United States)

    Rubtsov, Denis V; Griffin, Julian L

    2007-10-01

    The problem of model detection and parameter estimation for noisy signals arises in different areas of science and engineering including audio processing, seismology, electrical engineering, and NMR spectroscopy. We have adopted the Bayesian modeling framework to jointly detect and estimate signal resonances. This considers a model of the time-domain complex free induction decay (FID) signal as a sum of exponentially damped sinusoidal components. The number of model components and component parameters are considered unknown random variables to be estimated. A Reversible Jump Markov Chain Monte Carlo technique is used to draw samples from the joint posterior distribution on the subspaces of different dimensions. The proposed algorithm has been tested on synthetic data, the (1)H NMR FID of a standard of L-glutamic acid and a blood plasma sample. The detection and estimation performance is compared with Akaike information criterion (AIC), minimum description length (MDL) and the matrix pencil method. The results show the Bayesian algorithm superior in performance especially in difficult cases of detecting low-amplitude and strongly overlapping resonances in noisy signals.

  10. Authentication of beef versus horse meat using 60 MHz 1H NMR spectroscopy.

    Science.gov (United States)

    Jakes, W; Gerdova, A; Defernez, M; Watson, A D; McCallum, C; Limer, E; Colquhoun, I J; Williamson, D C; Kemsley, E K

    2015-05-15

    This work reports a candidate screening protocol to distinguish beef from horse meat based upon comparison of triglyceride signatures obtained by 60 MHz (1)H NMR spectroscopy. Using a simple chloroform-based extraction, we obtained classic low-field triglyceride spectra from typically a 10 min acquisition time. Peak integration was sufficient to differentiate samples of fresh beef (76 extractions) and horse (62 extractions) using Naïve Bayes classification. Principal component analysis gave a two-dimensional "authentic" beef region (p=0.001) against which further spectra could be compared. This model was challenged using a subset of 23 freeze-thawed training samples. The outcomes indicated that storing samples by freezing does not adversely affect the analysis. Of a further collection of extractions from previously unseen samples, 90/91 beef spectra were classified as authentic, and 16/16 horse spectra as non-authentic. We conclude that 60 MHz (1)H NMR represents a feasible high-throughput approach for screening raw meat.

  11. Synthesis and Resolution of the Atropisomeric 1,1'-Bi-2-Naphthol: An Experiment in Organic Synthesis and 2-D NMR Spectroscopy

    Science.gov (United States)

    Mak, Kendrew K. W.

    2004-01-01

    NMR spectroscopy is presented. It is seen that the experiment regarding the synthesis and resolution of 1,1'-Bi-2-naphtol presents a good experiment for teaching organic synthesis and NMR spectroscopy and provides a strategy for obtaining enantiopure compounds from achiral starting materials.

  12. Synthesis and Resolution of the Atropisomeric 1,1'-Bi-2-Naphthol: An Experiment in Organic Synthesis and 2-D NMR Spectroscopy

    Science.gov (United States)

    Mak, Kendrew K. W.

    2004-01-01

    NMR spectroscopy is presented. It is seen that the experiment regarding the synthesis and resolution of 1,1'-Bi-2-naphtol presents a good experiment for teaching organic synthesis and NMR spectroscopy and provides a strategy for obtaining enantiopure compounds from achiral starting materials.

  13. High-resolution 1H NMR spectroscopy of fish muscle, eggs and small whole fish via Hadamard-encoded intermolecular multiple-quantum coherence.

    Directory of Open Access Journals (Sweden)

    Honghao Cai

    Full Text Available BACKGROUND AND PURPOSE: Nuclear magnetic resonance (NMR spectroscopy has become an important technique for tissue studies. Since tissues are in semisolid-state, their high-resolution (HR spectra cannot be obtained by conventional NMR spectroscopy. Because of this restriction, extraction and high-resolution magic angle spinning (HR MAS are widely applied for HR NMR spectra of tissues. However, both of the methods are subject to limitations. In this study, the feasibility of HR (1H NMR spectroscopy based on intermolecular multiple-quantum coherence (iMQC technique is explored using fish muscle, fish eggs, and a whole fish as examples. MATERIALS AND METHODS: Intact salmon muscle tissues, intact eggs from shishamo smelt and a whole fish (Siamese algae eater are studied by using conventional 1D one-pulse sequence, Hadamard-encoded iMQC sequence, and HR MAS. RESULTS: When we use the conventional 1D one-pulse sequence, hardly any useful spectral information can be obtained due to the severe field inhomogeneity. By contrast, HR NMR spectra can be obtained in a short period of time by using the Hadamard-encoded iMQC method without shimming. Most signals from fatty acids and small metabolites can be observed. Compared to HR MAS, the iMQC method is non-invasive, but the resolution and the sensitivity of resulting spectra are not as high as those of HR MAS spectra. CONCLUSION: Due to the immunity to field inhomogeneity, the iMQC technique can be a proper supplement to HR MAS, and it provides an alternative for the investigation in cases with field distortions and with samples unsuitable for spinning. The acquisition time of the proposed method is greatly reduced by introduction of the Hadamard-encoded technique, in comparison with that of conventional iMQC method.

  14. Low-field (1)H NMR spectroscopy for distinguishing between arabica and robusta ground roast coffees.

    Science.gov (United States)

    Defernez, Marianne; Wren, Ella; Watson, Andrew D; Gunning, Yvonne; Colquhoun, Ian J; Le Gall, Gwénaëlle; Williamson, David; Kemsley, E Kate

    2017-02-01

    This work reports a new screening protocol for addressing issues of coffee authenticity using low-field (60MHz) bench-top (1)H NMR spectroscopy. Using a simple chloroform-based extraction, useful spectra were obtained from the lipophilic fraction of ground roast coffees. It was found that 16-O-methylcafestol (16-OMC, a recognized marker compound for robusta beans) gives rise to an isolated peak in the 60MHz spectrum, which can be used as an indicator of the presence of robusta beans in the sample. A total of 81 extracts from authenticated coffees and mixtures were analysed, from which the detection limit of robusta in arabica was estimated to be between 10% and 20% w/w. Using the established protocol, a surveillance exercise was conducted of 27 retail samples of ground roast coffees which were labelled as "100% arabica". None were found to contain undeclared robusta content above the estimated detection limit.

  15. Characterization of polysulfone and polysulfone/vanillin microcapsules by 1H NMR spectroscopy, solid-state 13C CP/MAS-NMR spectroscopy, and N2 adsorption-desorption analyses.

    Science.gov (United States)

    Peña, Brisa; de Ménorval, Louis-Charles; Garcia-Valls, Ricard; Gumí, Tània

    2011-11-01

    Textile detergent and softener industries have incorporated perfume microencapsulation technology to improve their products. Perfume encapsulation allows perfume protection until use and provides a long-lasting fragrance release. But, certain industrial microcapsules show low encapsulation capacity and low material stability. Polysulfone capsules have been already proposed to solve these drawbacks. Among them, PSf/Vanillin capsules were considered as a desirable system. They present both good material stability and high encapsulation capacity. However, several factors such as the final location of the perfume in the polymeric matrix, the aggregation state that it has in the capsule and its interaction with the capsule components have not been studied yet. These factors can provide vast information about the capsule performance and its improvement. With the aim to characterize these parameters, the physical and chemical properties of PSf/Vanillin capsules have been investigated by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and N(2) adsorption-desorption measurements. AFM micrograph and N(2) isotherms confirm that the presence of vanillin modify the physical structure of PSf/Vanillin microcapsules as it is trapped in the capsule porosity. NMR results show that vanillin is present in solid state in PSf/Vanillin microcapsules.

  16. Solution NMR Studies of Mycobacterium tuberculosis Proteins for Antibiotic Target Discovery

    Directory of Open Access Journals (Sweden)

    Do-Hee Kim

    2017-08-01

    Full Text Available Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, which triggers severe pulmonary diseases. Recently, multidrug/extensively drug-resistant tuberculosis strains have emerged and continue to threaten global health. Because of the development of drug-resistant tuberculosis, there is an urgent need for novel antibiotics to treat these drug-resistant bacteria. In light of the clinical importance of M. tuberculosis, 2067 structures of M. tuberculsosis proteins have been determined. Among them, 52 structures have been solved and studied using solution nuclear magnetic resonance (NMR. The functional details based on structural analysis of M. tuberculosis using NMR can provide essential biochemical data for the development of novel antibiotic drugs. In this review, we introduce diverse structural and biochemical studies on M. tuberculosis proteins determined using NMR spectroscopy.

  17. Investigation of multiaxial molecular dynamics by 2H MAS NMR spectroscopy.

    Science.gov (United States)

    Kristensen, J H; Hoatson, G L; Vold, R L

    1998-11-01

    The technique of 2H MAS NMR spectroscopy is presented for the investigation of multiaxial molecular dynamics. To evaluate the effects of discrete random reorientation a Lie algebraic formalism based on the stochastic Liouville-von Neumann equation is developed. The solution to the stochastic Liouville-von Neumann equation is obtained both in the presence and absence of rf irradiation. This allows effects of molecular dynamics to be evaluated during rf pulses and extends the applicability of the formalism to arbitrary multiple pulse experiments. Theoretical methods are presented for the description of multiaxial dynamics with particular emphasis on the application of vector parameters to represent molecular rotations. Numerical time and powder integration algorithms are presented that are both efficient and easy to implement computationally. The applicability of 2H MAS NMR spectroscopy for investigating molecular dynamics is evaluated from theoretical spectra. To demonstrate the potential of the technique the dynamics of thiourea-2H4 is investigated experimentally. From a series of variable temperature MAS and quadrupole echo spectra it has been found that the dynamics can be described by composite rotation about the CS and CN bonds. Both experiments are sensitive to the fast CS rotation which is shown to be described by the Arrhenius parameters E(CS) = 46.4 +/- 2.3 kJ mol(-1) and ln(A(CS))= 32.6 +/- 0.9. The MAS experiment represents a significant improvement by simultaneously allowing the dynamics of the slow CN rotation to be fully characterized in terms of E(CN) = 56.3 +/- 3.4 kJ mol(-1) and ln(A(CN)) = 25.3 +/- 1.1.

  18. Quantitative NMR spectroscopy of complex technical mixtures using a virtual reference: chemical equilibria and reaction kinetics of formaldehyde-water-1,3,5-trioxane.

    Science.gov (United States)

    Maiwald, Michael; Grützner, Thomas; Ströfer, Eckhard; Hasse, Hans

    2006-07-01

    Quantitative 1H NMR spectroscopy was used to study chemical equilibria and reaction kinetics of both the formation and decomposition of 1,3,5-trioxane in aqueous formaldehyde solutions. The reaction was homogeneously catalyzed with up to 0.10 g g(-1) sulfuric acid at temperatures between 360 and 383 K so that most of the experiments had to be carried out pressurized. The studied mixtures were complex due to the formation of methylene glycol and poly(oxymethylene) glycols in aqueous formaldehyde and the presence of considerable amounts of ionized species. Most common internal standards are decomposed by the hot sulfuric acid and external standards were not applicable using the flow NMR probe or pressurizable NMR sample tubes. Therefore, for the quantification of the small trioxane signals, a novel procedure was applied, in which electronically generated NMR signals were used as highly stable Virtual References (VR). The NMR decoupler channel with wave-form generator was used as the source of the reference signal, which was irradiated into the probe using the lock coil. Details on the experimental procedure are presented. It is shown that the presented method yields reliable quantitative reaction data for the complex studied mixtures.

  19. 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.

  20. NMR studies of nucleic acid dynamics

    Science.gov (United States)

    Al-Hashimi, Hashim M.

    2013-12-01

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

  1. Structure and Dynamics in Amphiphilic Bilayers: NMR and MD simulation Studies

    OpenAIRE

    2013-01-01

    Solid-state nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations were employed to study molecular structure and dynamics in amphiphilic bilayers. This thesis reports on method development and practical applications to two types of bilayer systems: simple cell membrane models composed of phosphatidylcholine lipids and cholesterol; and liquid crystals composed of ethyleneoxide-based surfactants often used in technological applications and in fundamental studies ...

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    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...... acid carbon atoms were measured by C-13 solid-state magic-angle-spinning (MAS) NMR using symmetry-based double-quantum (2Q) dipolar recoupling. This revealed the presence of C-13-C-13 distances of 3.85 angstrom, which correspond to the C-C distance in hydrogen-bonded carboxylic acid dimers. In spite...... of the presence of carboxylic groups in the polymer as demonstrated by C-13 CP/MAS NMR and IR spectroscopy, the absence of carboxylic protons in solid state H-1 NMR spectra indicate that they are mobile. We link the extraordinary stability of this system to the rigid nature, cross-linking through a hydrogen...

  3. Dihydroflavanonols from Cedrus deodara, A (13)C NMR study.

    Science.gov (United States)

    Agrawal, P K; Agarwal, S K; Rastogi, R P; Osterdahal, B G

    1981-09-01

    High resolution (13)C NMR study of taxifolin, cedeodarin, cedrin and their methyl ethers allowed unambiguous placement of the Me in 5,7-dihydroxyflavanonol nucleus, besides providing other valuable information on the substitution pattern in the molecule.

  4. NMR studies on polyphosphide Ce6Ni6P17

    Science.gov (United States)

    Koyama, T.; Yamada, H.; Ueda, K.; Mito, T.; Aoyama, Y.; Nakano, T.; Takeda, N.

    2016-02-01

    We report the result of 31P nuclear magnetic resonance (NMR) studies on Ce6Ni6P17. The observed NMR spectra show a Lorentzian-type and an asymmetric shapes, reflecting the local symmetry around each P site in the cubic unit cell. We have identified the observed NMR lines corresponding to three inequivalent P sites and deduced the temperature dependence of the Knight shift for each site. The Knight shifts increase with decreasing temperature down to 1.5 K, indicating a localized spin system of Ce6Ni6P17. Antiferromagnetic correlation between 4f spins is suggested from the negative sign of the Weiss-temperature.

  5. NMR and IR Spectroscopy for the Structural Characterization of Edible Fats and Oils: An Instrumental Analysis Laboratory

    Science.gov (United States)

    Crowther, Molly W.

    2008-01-01

    This article describes an upper-level instrumental laboratory for undergraduates that explores the complementary nature of IR and NMR spectroscopy for analysis of several edible fats and oils that are structurally similar but differ in physical properties and health implications. Five different fats and oils are analyzed for average chain length,…

  6. Functional dynamics of human FKBP12 revealed by methyl C-13 rotating frame relaxation dispersion NMR spectroscopy

    NARCIS (Netherlands)

    Brath, U; Akke, M; Yang, DW; Kay, LE; Mulder, FAA

    2006-01-01

    Transverse relaxation dispersion NMR spectroscopy can provide atom-specific information about time scales, populations, and the extent of structural reorganization in proteins under equilibrium conditions. A method is described that uses side-chain methyl groups as local reporters for conformational

  7. Response to the Letter to the Editor regarding "Determination of the fatty acid profile by 1H-NMR spectroscopy."

    Science.gov (United States)

    In expansion of previous work (G. Knothe, J.A. Kenar, Determination of the fatty acid profile by 1H-NMR spectroscopy, Eur. J. Lipid Sci. Technol. 2004, 106, 88-96), an additional approach is discussed for quantitating saturated fatty acids in the fatty acid profiles of common vegetable oils by 1H-NM...

  8. Multinuclear nanoliter one-dimensional and two-dimensional NMR spectroscopy with a single non-resonant microcoil

    NARCIS (Netherlands)

    Fratila, R.M.; Gomez, M.V.; Sykora, S.; Velders, A.H.

    2014-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique, but its low sensitivity and highly sophisticated, costly, equipment severely constrain more widespread applications. Here we show that a non-resonant planar transceiver microcoil integrated in a microfluidic chip (dete

  9. A multi-metabolite analysis of serum by H-1 NMR spectroscopy: Early systemic signs of Alzheimer's disease

    NARCIS (Netherlands)

    Tukiainen, T.; Tynkkynen, T.; Mäkinen, V.P.; Jylänki, P.P.; Kangas, A.J.; Hokkanen, J.; Vehtari, A.; Grohn, O.; Hallikainen, M.; Soininen, H.; Kivipelto, M.; Groop, P.H.; Kaski, K.; Laatikainen, R.; Soininen, P.; Pirttilä, T.; Ala-Korpela, M.

    2008-01-01

    A three-molecular-window approach for H-1 NMR spectroscopy of serum is presented to obtain specific molecular data on lipoproteins, Various low-molecular-weight metabolites, and individual lipid molecules together with their degree of (poly)(un)saturation. The multiple data were analysed with self-o

  10. Functional dynamics of human FKBP12 revealed by methyl C-13 rotating frame relaxation dispersion NMR spectroscopy

    NARCIS (Netherlands)

    Brath, U; Akke, M; Yang, DW; Kay, LE; Mulder, FAA

    2006-01-01

    Transverse relaxation dispersion NMR spectroscopy can provide atom-specific information about time scales, populations, and the extent of structural reorganization in proteins under equilibrium conditions. A method is described that uses side-chain methyl groups as local reporters for conformational

  11. High-resolution 1H-NMR spectroscopy of free and glycosidically linked O-acetylated sialic acids

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Haverkamp, J.; Halbeek, H. van; Dorland, L.; Pfeil, R.; Schauer, R.

    1982-01-01

    A number of naturally occurring and synthetic, partially O-acetylated derivatives of N-acetylneuraminic and N-glycoloylneuraminic acids have been investigated by 360-MHz 1H-NMR spectroscopy. O-Acetylation causes strong downfield shifts for the resonances of neighbouring sugar-skeleton protons. The c

  12. An efficient method and device for transfer of semisolid materials into solid-state NMR spectroscopy rotors.

    Science.gov (United States)

    Hisao, Grant S; Harland, Michael A; Brown, Robert A; Berthold, Deborah A; Wilson, Thomas E; Rienstra, Chad M

    2016-04-01

    The study of mass-limited biological samples by magic angle spinning (MAS) solid-state NMR spectroscopy critically relies upon the high-yield transfer of material from a biological preparation into the MAS rotor. This issue is particularly important for maintaining biological activity and hydration of semi-solid samples such as membrane proteins in lipid bilayers, pharmaceutical formulations, microcrystalline proteins and protein fibrils. Here we present protocols and designs for rotor-packing devices specifically suited for packing hydrated samples into Pencil-style 1.6 mm, 3.2 mm standard, and 3.2 mm limited speed MAS rotors. The devices are modular and therefore readily adaptable to other rotor and/or ultracentrifugation tube geometries.

  13. 31P NMR Study on Some Phosphorus-Containing Compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  14. NMR and Infrared Study of Thermal Oxidation of cis-1, 4-Polybutadiene

    Science.gov (United States)

    Gemmer, Robert V.; Golub, Morton A.

    1978-01-01

    A study of the microstructural changes occuring in CB during thermal, uncatalyzed oxidation was carried out. Although the oxidation of CB is accompanied by extensive crosslinking with attendant insolubilization, it was found possible to follow the oxidation of solid CB directly with C-13 NMR spectroscopy. The predominant products appearing in the C-13 NMR spectra of oxidized CB are epoxides. The presence of lesser amounts of alcohols, peroxides, and carbonyl structures was adduced from complementary infrared and NMR spectra of soluble extracts obtained from the oxidized, crosslinked CB. This distribution of functional groups contrasts with that previously reported for the autooxidation of 1,4-polyisoprene. The difference was rationalized in terms of the relative stabilities of intermediate radical species involved in the autoxidation of CB and 1,4-polyisoprene.

  15. Two-dimensional NMR spectroscopy links structural moieties of soil organic matter to the temperature sensitivity of its decomposition

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Schleucher, Jürgen

    2015-04-01

    Soil organic matter (SOM) represents a huge carbon pool, specifically in boreal ecosystems. Warming-induced release of large amounts of CO2 from the soil carbon pool might become a significant exacerbating feedback to global warming, if decomposition rates of boreal soils were more sensitive to increased temperatures. Despite a large number of studies dedicated to the topic, it has proven difficult to elucidate how the organo-chemical composition of SOM influences its decomposition, or its quality as a substrate for microbial metabolism. A great part of this challenge results from our inability to achieve a detailed characterization of the complex composition of SOM on the level of molecular structural moieties. 13C nuclear magnetic resonance (NMR) spectroscopy is a common tool to characterize SOM. However, SOM is a very complex mixture and the chemical shift regions distinguished in the 13C NMR spectra often represent many different molecular fragments. For example, in the carbohydrates region, signals of all monosaccharides present in many different polymers overlap. This overlap thwarts attempts to identify molecular moieties, resulting in insufficient information to characterize SOM composition. We applied two-dimensional (2D) NMR to characterize SOM with highly increased resolution. We directly dissolved finely ground litters and forest floors'fibric and humic horizons'of both coniferous and deciduous boreal forests in dimethyl sulfoxide and analyzed the resulting solution with a 2D 1H-13C NMR experiment. In the 2D planes of these spectra, signals of CH groups can be resolved based on their 13C and 1H chemical shifts, hence the resolving power and information content of these NMR spectra is hugely increased. The 2D spectra indeed resolved overlaps observed in 1D 13C spectra, so that hundreds of distinct CH groups could be observed and many molecular fragments could be identified. For instance, in the aromatics region, signals from individual lignin units could

  16. Intermolecular alignment in Y145Stop human prion protein amyloid fibrils probed by solid-state NMR spectroscopy.

    Science.gov (United States)

    Helmus, Jonathan J; Surewicz, Krystyna; Apostol, Marcin I; Surewicz, Witold K; Jaroniec, Christopher P

    2011-09-07

    The Y145Stop mutant of human prion protein, huPrP23-144, has been linked to PrP cerebral amyloid angiopathy, an inherited amyloid disease, and also serves as a valuable in vitro model for investigating the molecular basis of amyloid strains. Prior studies of huPrP23-144 amyloid by magic-angle-spinning (MAS) solid-state NMR spectroscopy revealed a compact β-rich amyloid core region near the C-terminus and an unstructured N-terminal domain. Here, with the focus on understanding the higher-order architecture of huPrP23-144 fibrils, we probed the intermolecular alignment of β-strands within the amyloid core using MAS NMR techniques and fibrils formed from equimolar mixtures of (15)N-labeled protein and (13)C-huPrP23-144 prepared with [1,3-(13)C(2)] or [2-(13)C]glycerol. Numerous intermolecular correlations involving backbone atoms observed in 2D (15)N-(13)C spectra unequivocally suggest an overall parallel in-register alignment of the β-sheet core. Additional experiments that report on intermolecular (15)N-(13)CO and (15)N-(13)Cα dipolar couplings yielded an estimated strand spacing that is within ∼10% of the distances of 4.7-4.8 Å typical for parallel β-sheets.

  17. Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy.

    Science.gov (United States)

    Thawarkar, Sachin; Khupse, Nageshwar D; Kumar, Anil

    2016-04-01

    Electrical conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4 ], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (1) H NMR chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3 COO] in D2 O and in [D6 ]DMSO are determined by using (1) H nuclei with pulsed field gradient spin-echo NMR spectroscopy.

  18. Conformational Analysis of Triazine Dendrimers: Using NMR Spectroscopy To Probe the Choreography of a Dendrimer's Dance.

    Science.gov (United States)

    Moreno, Karlos X; Simanek, Eric E

    2008-06-24

    One-dimensional (1D) and two-dimensional (2D) NMR studies are used to probe the conformation of a melamine dendrimer bearing unique NMR signals from the core to the periphery. Four conceptual anchors for dendrimer conformation emerge from these experiments. First, changes in isomer populations observed by (1)H NMR reveal the onset of globular structure. Second, NOE complexity emerges with globular structure: variable temperature NOESY studies show that the peripheral groups, BOC-protected aliphatic amines, fold back into the globular core of the macromolecule at 75 degrees C in DMSO-d(6). Third, variable temperature coefficients measured for NH protons suggest that solvent is largely excluded from the interior of the dendrimer: the carbamate NH groups of the periphery are most sensitive to temperature while the NHs nearest the core show little temperature dependence. Conformation is influenced by solvent choice: backfolding is observed in DMSO-d(6), but not in either CDCl(3) or CD(3)OD. Finally, relaxation studies show that peripheral groups are more dynamic than groups at the core. These anchors consolidate observations made by many groups on disparate systems within a common architecture.

  19. Interfaces in polymer nanocomposites – An NMR study

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-09

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

  20. Analysis of structural variability in pharmaceutical excipients using solid-state NMR spectroscopy.

    Science.gov (United States)

    Sperger, Diana M; Munson, Eric Jon

    2011-09-01

    Polysaccharide-based excipients comprise the majority of most solid dosage forms and can vary dramatically in terms of structural and functionally related properties. Analytical methods for characterizing these important formulation components are crucial. Solid-state NMR spectroscopy (SSNMR) can provide a wealth of information on these materials while offering the advantages of non-destructive sample preparation and selectivity. The overall objective of this work is to identify SSNMR parameters that can be used to detect differences among these excipients. Excipients were obtained from a wide range of suppliers and analyzed as received; (13)C SSNMR spectra were acquired using a Chemagnetics CMX-300 spectrometer operating at approximately 75 MHz. The resolution of SSNMR signals of many excipients allows for positive identification of the major form present. Alginic acid and sodium alginate can be differentiated based on carbonyl peak position. Analysis of relative peak intensities provides insight into the purity of a carrageenan sample compared to known standards. The SSNMR spectrum of starch can be used to identify the source and to quantitate the amorphous and crystalline content. Relaxation values and peak areas of starch derivatives can be related to the degree of hydrolysis, providing an alternative method for determining dextrose equivalent. Differences in peak intensities and relaxation time values of HPMC samples can be correlated to the amount of methoxy subsituent groups. Important characteristics of excipients such as form identification, structural differences, crystalline and amorphous content, and water content variations can be detected using SSNMR spectroscopy.

  1. Characterization of bio-oil from hydrothermal liquefaction of organic waste by NMR spectroscopy and FTICR mass spectrometry.

    Science.gov (United States)

    Leonardis, Irene; Chiaberge, Stefano; Fiorani, Tiziana; Spera, Silvia; Battistel, Ezio; Bosetti, Aldo; Cesti, Pietro; Reale, Samantha; De Angelis, Francesco

    2013-01-01

    Solid wastes of organic origins are potential feedstocks for the production of liquid biofuels, which could be suitable alternatives to fossil fuels for the transport and heating sectors, as well as for industrial use. By hydrothermal liquefaction, the wet biomass is partially transformed into a water-immiscible, oil-like organic matter called bio-oil. In this study, an integrated NMR spectroscopy/mass spectrometry approach has been developed for the characterization of the hydrothermal liquefaction of bio-oil at the molecular level. (1)H and (13)C NMR spectroscopy were used for the identification of functional groups and gauging the aromatic carbon content in the mixture. GC-MS analysis revealed that the volatile fraction was rich in fatty acids, as well as in amides and esters. High-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been applied in a systematic way to fully categorize the bio-oil in terms of different classes of components, according to their molecular formulas. Most importantly, for the first time, by using this technique, and for the liquefaction bio-oil characterization in particular, FT-MS data have been used to develop a methodology for the determination of the aromatic versus aliphatic carbon and nitrogen content. It is well known that, because they resist hydrogenation and represent sources of polluting species, both aromatic molecules and nitrogen-containing species raise concerns for subsequent upgrading of bio-oil into a diesel-like fuel. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. NMR and EPR Studies of Free-Radical Intermediates from Experiments Mimicking the Winds on Mars

    DEFF Research Database (Denmark)

    Jakobsen, Hans J.; Song, Likai; Gan, Zhehong

    2016-01-01

    A new kind of solid gas chemical reactions has been investigated using solid-state powder H-2, C-13, and Si-29 NMR and EPR spectroscopies. These studies involve reactions between a silicate-created Si free-radical intermediate and a few ordinary gases such as isotopically H-2-, C-13-, and O-17......)-C-13, (encapsulation of the gas) and the indication of a congested methyl group in the product from reaction with methane....

  3. Glycerol as a reference material for fecal fat quantitation using low-resolution time domain ¹H NMR spectroscopy.

    Science.gov (United States)

    Corsetti, James P; Sterry, Judy; Sakpal, Manisha; Lefevre, Brian H; Ryan, Dan

    2011-11-01

    To assess glycerol as reference material for low-resolution time-domain (1)H NMR analysis of fecal fat. NMR analysis of fecal fat in stool samples with added glycerol was used to assess linearity, recovery, and relationship with NMR lipid signal. The study revealed for added glycerol excellent linearity (r=0.9998), recovery (101-104%), and linear relationship with simulated fecal fat content. Glycerol is an effective reference material for NMR fecal fat analysis. Copyright © 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  4. NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

    Energy Technology Data Exchange (ETDEWEB)

    Foerland, Kjersti

    2005-07-01

    In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41.

  5. Development and application of a membrane cyclone reactor for in vivo NMR spectroscopy with high microbial cell densities.

    Science.gov (United States)

    Hartbrich, A; Schmitz, G; Weuster-Botz, D; de Graaf, A A; Wandrey, C

    1996-09-20

    A new bioreactor system has been developed for in vivo NMR spectroscopy of microorganisms under defined physiological conditions. This cyclone reactor with an integrated NMR flow cell is continuously operated in the magnet of a 400-MHz wide-bore NMR spectrometer system. The residence times of medium and cells are decoupled by a circulation-integrated cross-flow microfiltration module to achieve higher cell densities as compared to continuous fermentations without cell retention (increase in cell density up to a factor of 10 in steady state). Volumetric mass transfer coefficients k(L)a of more than 1.0 s(-1) are possible in the membrane cyclone reactor, ensuring adequate oxygen supply [oxygen transfer rate >15,000 mg O(2) .(L h)(-1)] of high cell densities. With the aid of the membrane cyclone reactor we were able to show, using continuous in vivo (31)P NMR spectroscopy of anaerobic glucose fermentation by Zymomonas mobilis, that the NMR signal intensity was directly proportional to the cell concentration in the reactor. The concentration profiles of intracellular inorganic phosphate, NAD(H), NDP, NTP, UDP-sugar, a cyclic pyrophosphate, two sugar phosphate pools, and extracellular inorganic phosphate were recorded after a shift from one steady state to another. The intracellular cyclic pyrophosphate had not been detected before in in vitro measurements of Zymomonas mobilis extracts due to the high instability of this compound. Using continuous in vivo (13)C NMR spectroscopy of aerobic glucose utilization by Corynebacterium glutamicum at a density of 25 g(cell dry weight) . L(-1), the membrane cyclone reactor served to measure the different dynamics of labeling in the carbon atoms of L-lactate, L-glutamate, succinate, and L-lysine with a time resolution of 10 min after impressing a [1-(13)C]-glucose pulse.

  6. An in vitro model for the in vivo mobilization of cadmium by chelating agents using 113Cd-NMR spectroscopy.

    Science.gov (United States)

    Beaty, J A; Jones, M M; Wilson, D J; Ma, L

    1992-01-01

    An in vitro method, based on 113Cd-NMR spectroscopy, that provides an alternative to the use of animals for an initial screening of cadmium antagonists is presented. The relative values of the effective stability constants of potential chelating antagonists for cadmium are estimated by using 113Cd-NMR spectroscopy to determine the concentrations of the cadmium species involved in appropriate competitive equilibria. This is accomplished via an examination of the competition between the proposed antagonist and EDTA (ethylenediaminetetraacetic acid) for cadmium-113; previously, EDTA has been shown to be capable of removing cadmium from such in vivo binding sites as metallothionein. The reactions proceed via the stepwise addition of three dithiocarbamate groups to the cadmium accompanied by the concurrent stepwise release of donor groups from the EDTA. The resulting 113Cd-NMR data allow for the determination of the overall stability constant for the complex formed between cadmium and N-methyl-D-glucamine dithiocarbamate, iminodiacetic acid dithiocarbamate, proline dithiocarbamate, sarcosine dithiocarbamate. The use of 113Cd-NMR spectroscopy has the potential for providing direct evidence on the effectiveness of chelate antagonists to compete with endogenous ligands for other toxic metal ions. This technique could prove very useful for other compounds that are not stable enough toward acid and/or base to be examined by standard titrimetric methods.

  7. "Pulse pair technique in high resolution NMR" a reprint of the historical 1971 lecture notes on two-dimensional spectroscopy.

    Science.gov (United States)

    Jeener, Jean; Alewaeters, Gerrit

    2016-05-01

    The review articles published in "Progress in NMR Spectroscopy" are usually invited treatments of topics of current interest, but occasionally the Editorial Board may take an initiative to publish important historical material that is not widely available. The present article represents just such a case. Jean Jeener gave a lecture in 1971 at a summer school in Basko Polje, in what was then called Yugoslavia. As is now widely known, Jean Jeener laid down the foundations in that lecture of two - and higher - dimensional NMR spectroscopy by proposing the homonuclear COSY experiment. Jeener realized that the new proposal would open the door towards protein NMR and molecular structure determinations, but he felt that useful versions of such experiments could not be achieved with the NMR, computer and electronics technology available at that time, so that copies of the lecture notes were circulated (the Basko Polje lecture notes by J. Jeener and G. Alewaeters), but no formal publication followed. Fortunately, Ernst, Freeman, Griffin, and many others were more far-sighted and optimistic. An early useful extension was Ernst's proposal to replace the original projection/reconstruction technique of MRI by the widely adopted Fourier transform method inspired by the Basko Polje lecture. Later, the pulse method spread over many fields of spectroscopy as soon as the required technology became available. Jean Jeener, Emeritus professor, Université Libre de Bruxelles. Geoffrey Bodenhausen, Ecole Normale Supérieure, Paris.

  8. Binding of phenol and differently halogenated phenols to dissolved humic matter as measured by NMR spectroscopy.

    Science.gov (United States)

    Smejkalová, Daniela; Spaccini, Riccardo; Fontaine, Barbara; Piccolo, Alessandro

    2009-07-15

    1H- and 19F-NMR measurements of spin-lattice (T1) and spin-spin (T2) relaxationtimes and diffusion ordered spectroscopy (DOSY) were applied to investigate the association of nonsubstituted (phenol (P)) and halogen-substituted (2,4-dichlorophenol (DCP); 2,4,6-trichlorophenol (TCP), and 2,4,6-trifluorophenol (TFP) phenols with a dissolved humic acid (HA). T1 and T2 values for both 1H and 19F in phenols decreased with enhancing HA concentration, indicating reduction in molecular mobility due to formation of noncovalent interactions. Moreover, correlation times (tau c) for different hydrogen and fluorine atoms in phenols showed that anisotropic mobility turned into isotropic motion with HA additions. Changes in relaxation times suggested that DCP and TCP were more extensively bound to HA than P and TFP. This was confirmed by diffusion measurements which showed full association of DCP and TCP to a less amount of HA than that required for entire complexation of P and TFP. Calculated values of binding constants (Ka) reflected the overall NMR behavior, being significantly larger for DCP- and TCP-HA (10.04 +/- 1.32 and 4.47 +/- 0.35 M(-1), respectively) than for P- and TFP-HA complexes (0.57 +/- 0.03 and 0.28 +/- 0.01 M(-1), respectively). Binding increased with decreasing solution pH, thus indicating a dependence on the fraction of protonated form (alpha) of phenols in solution. However, it was found that the hydrophobicity conferred to phenols by chlorine atoms on aromatic rings is a stronger drive than alpha for the phenols repartition within the HA hydrophobic domains.

  9. The 'Nuts and Bolts' of 13C NMR Spectroscopy at Elevated-Pressures and -Temperatures for Monitoring In Situ CO2 Conversion to Metal Carbonates

    Science.gov (United States)

    Moore, J. K.; Surface, J. A.; Skemer, P. A.; Conradi, M. S.; Hayes, S. E.

    2013-12-01

    We will present details of newly-constructed specialized NMR designed to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies on unmixed slurries of minerals in the presence of CO2 or other gases. This static probe is capable of achieving 300 bar, 300C conditions, and it is designed to spectroscopically examine 13C signals in mixtures of solids, liquids, gases, and supercritical fluids. Ultimately, our aim is to monitor CO2 uptake in both ultramafic rocks and in more porous geological materials to understand the mechanisms of chemisorption as a function of temperature, pressure and pH. We will give details of the hardware setup, and we will show a variety of static in situ NMR, as well as ex situ 'magic-angle spinning' NMR to show the analyses that are possible of minerals in pure form and in mixtures. In addition, specific NMR pulse sequences, techniques, and modeling will be described in detail. In this in situ NMR probe, we are able to simulate processes at geologically relevant fluid pressures and temperatures, monitoring the kinetics of CO2 conversion to carbonates. The in situ NMR experiments consist of heterogeneous mixtures of rock, salty brine solution, and moderate pressure CO2 gas at elevated temperatures. The purpose of studying these reactions is to determine conditions that affect the efficacy of carbonate formation in various targeted geological reservoirs (i.e., peroditite, or others). Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals, including metastable intermediates (such as hydromagnesite, or dypingite in the case of magnesium carbonate species, or vaterite in the case of calcium carbonate species). Such species are distinguishable from a combination of the 13C isotropic chemical shift, the static 13C lineshape, and changes in spin-lattice (T1) relaxation times. We will demonstrate that NMR can be used for quantitative

  10. 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

    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...... in the cement phases. The role of flouride ions is of special interest for mineralized Portland cements and it demonstrated that the location of these anions in anhydrous and hydrated Portland cements can be clarified using 19F MAS or 29Si{19F} CP/MAS NMR despite these cements contain only about 0.2 wt...

  11. Styrylpyrylium Salts: 1H and 13C NMR High-Resolution Spectroscopy (1D and 2D

    Directory of Open Access Journals (Sweden)

    Jean Claude W. Ouédraogo

    2010-01-01

    Full Text Available 1H and 13C NMR high-resolution spectroscopy (1D and 2D (1H, 1H-COSY, HSQC, HMBC for four styrylpyrylium perchlorates were carried out and signal attributions are reported. Chemical shifts observed on 13C NMR spectra for the styrylpyrylium salts were compared with net atomic charge for carbon obtained by AM1 semiempirical calculations. The position of the styryl group present low effect on chemical shifts for carbon atoms, while the presence of methyl group led to the unshielding of the substituted carbon.

  12. Two-dimensional NMR spectroscopy strongly enhances soil organic matter composition analysis

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Hedenström, Mattias; Schleucher, Jürgen

    2016-04-01

    Soil organic matter (SOM) is the largest terrestrial carbon pool and strongly affects soil properties. With climate change, understanding SOM processes and turnover and how they could be affected by increasing temperatures becomes critical. This is particularly key for organic soils as they represent a huge carbon pool in very sensitive ecosystems, like boreal ecosystems and peatlands. Nevertheless, characterization of SOM molecular composition, which is essential to elucidate soil carbon processes, is not easily achieved, and further advancements in that area are greatly needed. Solid-state one-dimensional (1D) 13C nuclear magnetic resonance (NMR) spectroscopy is often used to characterize its molecular composition, but only provides data on a few major functional groups, which regroup many different molecular fragments. For instance, in the carbohydrates region, signals of all monosaccharides present in many different polymers overlap. This overlap thwarts attempts to identify molecular moieties, resulting in insufficient information to characterize SOM composition. Here we show that two-dimensional (2D) liquid-state 1H-13C NMR spectra provided much richer data on the composition of boreal plant litter and organic surface soil. The 2D spectra indeed resolved overlaps observed in 1D 13C spectra and displayed signals from hundreds of identifiable molecular groups. For example, in the aromatics region, signals from individual lignin units could be recognized. It was hence possible to follow the fate of specific structural moieties in soils. We observed differences between litter and soil samples, and were able to relate them to the decomposition of identifiable moieties. Sample preparation and data acquisition were both simple and fast. Further, using multivariate data analysis, we aimed at linking the detailed chemical fingerprints of SOM to turnover rates in a soil incubation experiment. With the multivariate models, we were able to identify specific molecular

  13. Solid state NMR study calcium phosphate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, J.L.; Facchini, L.; Legrand, A.P. (Laboratoire de Physique Quantique, Paris (France). CNRS, URA421, ESPCI); Rey, C. (CNRS, Toulouse (France). ENSC. Laboratoire de Physico-chimie des Solides); Lemaitre, J. (EPF Lausanne (France). Laboratoire de Technologie des Poudres)

    1990-04-01

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

  14. Fresco paintings studied by unilateral NMR

    Science.gov (United States)

    Proietti, N.; Capitani, D.; Lamanna, R.; Presciutti, F.; Rossi, E.; Segre, A. L.

    2005-11-01

    Unilateral NMR has been used to monitor the state of conservation of frescoes in the Vasari's house in Florence. The causes of deterioration of ancient frescoes are varied, which result in the detachment and crumbling of the painted film from the supporting plaster and in the outcropping of salts. Unilateral measurements of Hahn echo performed on such frescoes have allowed a perfect identification of the detachment of the painted film from the plaster. The presence of soluble salts on the pictorial film affects the spin-spin relaxation times, T2. It is then possible using this technique, to characterize the effect of chemical treatments, of cleansing and consolidation procedures using the distribution of T2 spin-spin relaxation times.

  15. Effect on the content of n-acetylaspartate, total creatine, choline containing compounds, and lactate in the hippocampus of rats exposed to aromatic white spirit for three weeks measured by NMR spectroscopy

    DEFF Research Database (Denmark)

    Steensgaard, A; Ostergaard, G; Jensen, C V;

    1996-01-01

    parameters in vivo, and to examine the same subjects repeatedly over time. NMR spectroscopy was used to study the effects of organic solvents in rats. Rats were exposed to 0, 400 ppm, or 800 ppm of aromatic white spirit 6 hr/day, 7 days/week for 3 weeks. During the first week, the rats showed signs...... spirit induces changes in neurotransmitter concentrations, indices of oxidative stress, and electrophysiological parameters. Others have confirmed that acute behavioural effects can be induced by short-term high-level exposure. With NMR spectroscopy technique it is possible to study neurochemical...... of irritation of mucous membranes, and appeared to be sedated. Both types of effect gradually diminished during the second week. The rats were examined by single volume of interest (VOI) NMR spectroscopy. N-acetylaspartate, creatinine and phosphocreatinine, and choline containing compounds were measured...

  16. Analysis of organic matter at the soil-water interface by NMR spectroscopy: Implications for contaminant sorption processes

    Science.gov (United States)

    Simpson, M.; Simpson, A.

    2009-05-01

    Contaminant sorption to soil organic matter (OM) is the main fate of nonionic, hydrophobic organic contaminants in terrestrial environments and a number of studies have suggested that both soil OM structure and physical conformation (as regulated by the clay mineral phase) govern contaminant sorption processes. To investigate this further, a number of soil samples were characterized by both solid-state 13 C Cross Polarization Magic Angle Spinning (CPMAS) NMR and 1H High Resolution Magic Angle Spinning (HR- MAS) NMR. HR-MAS NMR is an innovative NMR method that allows one to examine samples that are semi- solid using liquid state NMR methods (ie: observe 1H which is more sensitive than 13C). With HR-MAS NMR, only those structures that are in contact with the solvent are NMR visible thus one can probe different components within a mixture using different solvents. The 1H HR-MAS NMR spectrum of a grassland soil swollen in water (D2O) is dominated by signals from alkyl and O-alkyl structures but signals from aromatic protons are negligible (the peak at ~8.2ppm is attributed to formic acid). When the soil is swollen in DMSO-d6, a solvent which is more penetrating and capable of breaking hydrogen bonds, aromatic signals are visible suggesting that the aromatic structures are buried within the soil matrix and do not exist at the soil-water interface. The 13C solid-state NMR data confirms that aromatic carbon is present in substantial amounts (estimated at ~40% of the total 13C signal) therefore, the lack of 1H aromatic signals in the HR-MAS NMR spectrum indicates that aromatic structures are buried and that the soil-water interface is dominated by aliphatic chains, carbohydrates, and peptides. The NMR data indicates that the mineral component of soils governs the physical conformation of OM at the soil-water interface.

  17. Adsorption-desorption induced structural changes of Cu-MOF evidenced by solid state NMR and EPR spectroscopy.

    Science.gov (United States)

    Jiang, Yijiao; Huang, Jun; Kasumaj, Besnik; Jeschke, Gunnar; Hunger, Michael; Mallat, Tamas; Baiker, Alfons

    2009-02-18

    Adsorption-desorption induced structural changes of Cu(bpy)(H(2)O)(2)(BF(4)),(bpy) (bpy = 4,4'-bipyridine) [Cu-MOF] have been evidenced by combined NMR and EPR spectroscopy. Upon adsorption of probe molecules even at a few mbar, EPR spectra show that they are activated to form complexes at Cu(II) sites, which results in a change of the Cu-MOF's structure as indicated by a high-field shift of the (11)B MAS NMR. After desorption, both EPR and (11)B MAS NMR spectra evidenced that the structure of the Cu-MOF reversibly shifted to the original state. This observation indicates that MOFs can undergo structural changes during processes where adsorption-desorption steps are involved such as gas storage, separation, and catalysis.

  18. NMR studies on antitumor drug candidates, berberine and berberrubine

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Young Wook; Jung, Jin Won; Kang, Mi Ran; Chung, In Kwon; Lee, Weon Tae [Yonsei Univ., Seoul (Korea, Republic of)

    2002-03-01

    Berberine and berberrubine, which display antitumor activity, have also demonstrated distinct enzyme-poisoning activities by stabilizing topoisomerase II-DNA cleavable complexes. The protoberberine berberrubine differs in chemical structure with berberine at only one position, however, it shows a prominent activity different from berberine. Solution structures of berberine and berberrubine determined by NMR spectroscopy are similar, however, the minor structural rearrangement has been observed near 19 methoxy or hydroxyl group. We suggest that the DNA cleavage activities of topoisomerase II poisons could be correlated with both chemical environments and minor structural change together with hydrophobicity of interacting side chains of drugs with DNA molecules.

  19. Screening and assignment of phenylboronic acid and its anhydride formation by NMR spectroscopy

    Science.gov (United States)

    Chaudhari, Sachin R.

    2015-08-01

    The study discusses an approach that allows simultaneous determination of boronic acid and its anhydride without the need for tedious physical separation of the mixture. The assignment of the proton spectra of monomer, dimer and trimer was achieved by combining utility of 1D and 2D experimental techniques including 2D DOSY. The differential intensities of NMR peaks and supplementary resonances were detected in low polar solvents, such as, chloroform, toluene and in a non-polar solvent benzene. A fascinating phenomenon is observed at lower temperature where there is a formation of aryl boronic acid with the disappearance of boraxine formation.

  20. Metabolic Profiling of Cells in Response to Drug Treatment using (1)H High-resolution Magic Angle Spinning (HR-MAS) NMR Spectroscopy.

    Science.gov (United States)

    Vermathen, Martina; Diserens, Gaëlle; Vermathen, Peter; Furrer, Julien

    2017-03-29

    High-resolution magic angle spinning (HR-MAS) is an NMR technique that provides access to well resolved liquid-like 1H NMR spectra of semi-solid samples. Therefore, 1H HR-MAS NMR spectroscopy has become an important tool for the direct analysis of biological samples such as tissues and cells in a mostly non-destructive way. Here, we focus on the application of HR-MAS NMR combined with multivariate statistical methods used for metabolic profiling of cells and in particular for the study of cellular metabolic responses to drug exposure. The principles of HR-MAS and the metabolomic approach are briefly described. As an example, a study on the metabolic response of different cell types towards treatment with a highly cytotoxic hexacationic ruthenium metallaprism as potential anti-cancer drug is presented. Specific metabolites and metabolic pathways are suggested to be associated with the cellular response. The study demonstrates the potential of HR-MAS metabolomics applied to cells for addressing the intracellular processes involved in the treatment with organometallic drugs.