In situ high temperature MAS NMR study of the mechanisms of catalysis. Ethane aromatization on Zn-modified zeolite BEA.

Science.gov (United States)

Arzumanov, Sergei S; Gabrienko, Anton A; Freude, Dieter; Stepanov, Alexander G

2009-04-01

Ethane conversion into aromatic hydrocarbons over Zn-modified zeolite BEA has been analyzed by high-temperature MAS NMR spectroscopy. Information about intermediates (Zn-ethyl species) and reaction products (mainly toluene and methane), which were formed under the conditions of a batch reactor, was obtained by (13)C MAS NMR. Kinetics of the reaction, which was monitored by (1)H MAS NMR in situ at the temperature of 573K, provided information about the reaction mechanism. Simulation of the experimental kinetics within the frames of the possible kinetic schemes of the reaction demonstrates that a large amount of methane evolved under ethane aromatization arises from the stage of direct ethane hydrogenolysis.

MAS NMR of HIV-1 protein assemblies

Science.gov (United States)

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

2015-04-01

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

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

International Nuclear Information System (INIS)

Zanatta, N.; Borer, P.N.; Levy, G.C.

1986-01-01

The unique spectral properties of 13 C-NMR for studying nucleic acids and some of the important features of 13 C-NMR in oligonucleotide studies are demostrated. The main difficulty in studying oligonucleotides by 13 C-NMR and recent improvements in NMR instrumentation and advances in oligonucleotide synthesis are presented. The high resolution 13 C-NMR spectra, T 1 relaxation times and NOEs were measured for duplex of the self-complementary oligo-DNAs: d(CG) 3 and d(GGTATACC) are studied. The target of this study is to developed a systematic 13 C-NMR spectral assignment and to investigate the structure and dynamics of these two sequences by this techniques. (M.J.C.) [pt

Application of 13C-labeling and 13C-13C COSY NMR experiments in the structure determination of a microbial natural product.

Science.gov (United States)

Kwon, Yun; Park, Sunghyouk; Shin, Jongheon; Oh, Dong-Chan

2014-08-01

The elucidation of the structures of complex natural products bearing many quaternary carbons remains challenging, even in this advanced spectroscopic era. (13)C-(13)C COSY NMR spectroscopy shows direct couplings between (13)C and (13)C, which comprise the backbone of a natural product. Thus, this type of experiment is particularly useful for natural products bearing consecutive quaternary carbons. However, the low sensitivity of (13)C-based NMR experiments, due to the low natural abundance of the (13)C nucleus, is problematic when applying these techniques. Our efforts in the (13)C labeling of a microbial natural product, cyclopiazonic acid (1), by feeding (13)C-labeled glucose to the fungal culture, enabled us to acquire (13)C-(13)C COSY NMR spectra on a milligram scale that clearly show the carbon backbone of the compound. This is the first application of (13)C-(13)C COSY NMR experiments for a natural product. The results suggest that (13)C-(13)C COSY NMR spectroscopy can be routinely used for the structure determination of microbial natural products by (13)C-enrichment of a compound with (13)C-glucose.

Solubilization and localization of weakly polar lipids in unsonicated egg phosphatidylcholine: A 13C MAS NMR study

International Nuclear Information System (INIS)

Hamilton, J.A.; Fujito, D.T.; Hammer, C.F.

1991-01-01

The weakly polar lipids cholesteryl ester, triacylglycerol, and diacylglycerol incorporate to a limited extent into the lamellar structure of small unilamellar vesicles. The localization of the carbonyl group(s) at the aqueous interface was detected by [ 13 C]carbonyl chemical shift changes relative to the neat unhydrated lipid. This study uses 13 C NMR to investigate the interactions of thes lipids with unsonicated (multilamellar) phosphatidylcholine, a model system for cellular membranes and surfaces of emulsion particles with low curvature. Magic angle spinning reduced the broad lines of the unsonicated dispersions to narrow lines comparable to those from sonicated dispersions. [ 13 C]Carbonyl chemical shifts revealed incorporation of the three lipids into the lamellar structure of the unsonicated phospholipids and a partial hydration of the carbonyl groups similar to that observed in small vesicles. Other properties of interfacial weakly polar lipids in multilayers were similar to those in small unilamellar bilayers. There is thus a general tendency of weakly polar lipids to incorparate at least to a small extent into the lamellar structure of phospholipids and take on interfacial properties that are distinct from their bulk-phase properties. This pool of surface-located lipid is likely to be directly involved in enzymatyic transformations and protein-mediated transport. The 13 C magic angle spinning NMR method may be generally useful for determining the orientation of molecules in model membranes

Quartz Crystal Temperature Sensor for MAS NMR

Science.gov (United States)

Simon, Gerald

1997-10-01

Quartz crystal temperature sensors (QCTS) were tested for the first time as wireless thermometers in NMR MAS rotors utilizing the NMR RF technique itself for exiting and receiving electro-mechanical quartz resonances. This new tool in MAS NMR has a high sensitivity, linearity, and precision. When compared to the frequently used calibration of the variable temperature in the NMR system by a solid state NMR chemical shift thermometer (CST), such as lead nitrate, QCTS shows a number of advantages. It is an inert thermometer in close contact with solid samples operating parallel to the NMR experiment. QCTS can be manufactured for any frequency to be near a NMR frequency of interest (typically 1 to 2 MHz below or above). Due to the strong response of the crystal, signal detection is possible without changing the tuning of the MAS probe. The NMR signal is not influenced due to the relative sharp crystal resonance, restricted excitation by finite pulses, high probeQvalues, and commonly used audio filters. The quadratic dependence of the temperature increase on spinning speed is the same for the QCTS and for the CST lead nitrate and is discussed in terms of frictional heat in accordance with the literature about lead nitrate and with the results of a simple rotor speed jump experiment with differently radial located lead nitrate in the rotor.

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...

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

International Nuclear Information System (INIS)

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

2006-01-01

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

A software framework for analysing solid-state MAS NMR data

International Nuclear Information System (INIS)

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

2011-01-01

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

31P Solid-state MAS NMR spectra

International Nuclear Information System (INIS)

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

1989-01-01

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

Direct 13C NMR Detection in HPLC Hyphenation Mode

DEFF Research Database (Denmark)

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

2012-01-01

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

Structure determination of uniformly {sup 13}C, {sup 15}N labeled protein using qualitative distance restraints from MAS solid-state {sup 13}C-NMR observed paramagnetic relaxation enhancement

Energy Technology Data Exchange (ETDEWEB)

Tamaki, Hajime [Hokkaido University, Graduate School of Life Science (Japan); Egawa, Ayako [Osaka University, Institute for Protein Research (Japan); Kido, Kouki [Hokkaido University, Graduate School of Life Science (Japan); Kameda, Tomoshi [National Institute of Advanced Industrial Science and Technology, Biotechnology Research Institute for Drug Discovery (Japan); Kamiya, Masakatsu; Kikukawa, Takashi; Aizawa, Tomoyasu [Hokkaido University, Faculty of Advanced Life Science (Japan); Fujiwara, Toshimichi [Osaka University, Institute for Protein Research (Japan); Demura, Makoto, E-mail: demura@sci.hokudai.ac.jp [Hokkaido University, Faculty of Advanced Life Science (Japan)

2016-01-15

Magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) is a powerful method for structure determination of insoluble biomolecules. However, structure determination by MAS solid-state NMR remains challenging because it is difficult to obtain a sufficient amount of distance restraints owing to spectral complexity. Collection of distance restraints from paramagnetic relaxation enhancement (PRE) is a promising approach to alleviate this barrier. However, the precision of distance restraints provided by PRE is limited in solid-state NMR because of incomplete averaged interactions and intermolecular PREs. In this report, the backbone structure of the B1 domain of streptococcal protein G (GB1) has been successfully determined by combining the CS-Rosetta protocol and qualitative PRE restraints. The derived structure has a Cα RMSD of 1.49 Å relative to the X-ray structure. It is noteworthy that our protocol can determine the correct structure from only three cysteine-EDTA-Mn{sup 2+} mutants because this number of PRE sites is insufficient when using a conventional structure calculation method based on restrained molecular dynamics and simulated annealing. This study shows that qualitative PRE restraints can be employed effectively for protein structure determination from a limited conformational sampling space using a protein fragment library.

Analysis of mercerization process based on the intensity change of deconvoluted resonances of 13C CP/MAS NMR: Cellulose mercerized under cooling and non-cooling conditions

International Nuclear Information System (INIS)

Miura, Kento; Nakano, Takato

2015-01-01

The area intensity change of C1, C4, and C6 in spectrum obtained by 13 C CP/MAS NMR and the mutual relationship between their changes were examined for cellulose samples treated with various concentrations of aqueous NaOH solutions under non-cooling and cooling conditions. The area intensity of C1-up and C6-down changed cooperatively with that of C4-down which corresponds to the crystallinity of samples: “-up” and “-down” are the up- and down- field component in a splitting peak of NMR spectrum, respectively. The intensity change of C1-up starts to decrease with decreasing in that of C4-down after that of C6-down is almost complete. These changes were more clearly observed for samples treated under cooling condition. It can be suggested that their characteristic change relates closely to the change in conformation of cellulose chains by induced decrystallization and the subsequent crystallization of cellulose II, and presumed that their changes at microscopic level relate to the macroscopic morphological changes such as contraction along the length of cellulose chains and recovery along the length. - Highlight: • Samples were mercerized at various NaOH concentrations under non-cooling and cooling. • The intensity change of C1 starts immediately after that of C6 is complete. • The creation of cell-II starts when decrystallization proceeds to a certain state. • This change relates closely to the change in conformation of cellulose chains. • The above change is more clearly found for samples treated under cooling

Effects of solvent concentration and composition on protein dynamics: 13C MAS NMR studies of elastin in glycerol-water mixtures.

Science.gov (United States)

Demuth, Dominik; Haase, Nils; Malzacher, Daniel; Vogel, Michael

2015-08-01

We use (13)C CP MAS NMR to investigate the dependence of elastin dynamics on the concentration and composition of the solvent at various temperatures. For elastin in pure glycerol, line-shape analysis shows that larger-scale fluctuations of the protein backbone require a minimum glycerol concentration of ~0.6 g/g at ambient temperature, while smaller-scale fluctuations are activated at lower solvation levels of ~0.2 g/g. Immersing elastin in various glycerol-water mixtures, we observe at room temperature that the protein mobility is higher for lower glycerol fractions in the solvent and, thus, lower solvent viscosity. When decreasing the temperature, the elastin spectra approach the line shape for the rigid protein at 245 K for all studied samples, indicating that the protein ceases to be mobile on the experimental time scale of ~10(-5) s. Our findings yield evidence for a strong coupling between elastin fluctuations and solvent dynamics and, hence, such interaction is not restricted to the case of protein-water mixtures. Spectral resolution of different carbon species reveals that the protein-solvent couplings can, however, be different for side chain and backbone units. We discuss these results against the background of the slaving model for protein dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of mercerization process based on the intensity change of deconvoluted resonances of {sup 13}C CP/MAS NMR: Cellulose mercerized under cooling and non-cooling conditions

Energy Technology Data Exchange (ETDEWEB)

Miura, Kento [Mitsubishi Rayon Co., Ltd. Otake Research Laboratories (Japan); Nakano, Takato, E-mail: tnakano@kais.kyoto-u.ac.jp [Laboratory of Biomaterials Design, Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University (Japan)

2015-08-01

The area intensity change of C1, C4, and C6 in spectrum obtained by {sup 13}C CP/MAS NMR and the mutual relationship between their changes were examined for cellulose samples treated with various concentrations of aqueous NaOH solutions under non-cooling and cooling conditions. The area intensity of C1-up and C6-down changed cooperatively with that of C4-down which corresponds to the crystallinity of samples: “-up” and “-down” are the up- and down- field component in a splitting peak of NMR spectrum, respectively. The intensity change of C1-up starts to decrease with decreasing in that of C4-down after that of C6-down is almost complete. These changes were more clearly observed for samples treated under cooling condition. It can be suggested that their characteristic change relates closely to the change in conformation of cellulose chains by induced decrystallization and the subsequent crystallization of cellulose II, and presumed that their changes at microscopic level relate to the macroscopic morphological changes such as contraction along the length of cellulose chains and recovery along the length. - Highlight: • Samples were mercerized at various NaOH concentrations under non-cooling and cooling. • The intensity change of C1 starts immediately after that of C6 is complete. • The creation of cell-II starts when decrystallization proceeds to a certain state. • This change relates closely to the change in conformation of cellulose chains. • The above change is more clearly found for samples treated under cooling.

Carbonaceous species (coke) characterization in zeolites by solid state {sup 13} C NMR; Caracterizacao de especies carbonaceas (coque) em zeolitos por RMN de {sup 13} C estado solido (CP/MAS)

Energy Technology Data Exchange (ETDEWEB)

Mota, Claudio J.A.; Menezes, Sonia C [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

1992-12-31

This work applies solid state {sup 13} C NMR for characterization of carbonaceous species (coke) deposited on zeolites after contact with n-hexane at 370 deg C. The results have shown two types of carbon: saturated (sp{sup 3}) and unsaturated (sp{sup 2}) 4 refs., 4 tabs.

Chemical structure changes in coals after low-temperature oxidation and demineralization by acid treatment as revealed by high resolution solid state 13C NMR

International Nuclear Information System (INIS)

Tekely, P.; Nicole, D.; Delpuech, J.-J.; Totino, E.; Muller, J.F.

1987-01-01

13 C CP/MAS NMR has been used for characterization of chemical structure changes in coals after low-temperature oxidation and prolonged demineralization by acid treatment. In both cases the changes take place mainly in the aliphatic part of coal molecules. 21 refs.; 3 figs.; 2 tabs

13C-NMR of diterpenes with pimarane skeleton

International Nuclear Information System (INIS)

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

1981-01-01

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

Spin-echo based diagonal peak suppression in solid-state MAS NMR homonuclear chemical shift correlation spectra

Science.gov (United States)

Wang, Kaiyu; Zhang, Zhiyong; Ding, Xiaoyan; Tian, Fang; Huang, Yuqing; Chen, Zhong; Fu, Riqiang

2018-02-01

The feasibility of using the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed in such a way that in the indirect dimension only the spin diffused signals are evolved, while all signals not involved in polarization transfer are refocused for cancellation. A data processing procedure is further introduced to reconstruct this acquired spectrum into a conventional two-dimensional homonuclear chemical shift correlation spectrum. A uniformly 13C, 15N labeled Fmoc-valine sample and the transmembrane domain of a human protein, LR11 (sorLA), in native Escherichia coli membranes have been used to illustrate the capability of the proposed method in comparison with standard 13C-13C chemical shift correlation experiments.

Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials

Science.gov (United States)

Paik, Younkee

Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

Optimized slice-selective 1H NMR experiments combined with highly accurate quantitative 13C NMR using an internal reference method

Science.gov (United States)

Jézéquel, Tangi; Silvestre, Virginie; Dinis, Katy; Giraudeau, Patrick; Akoka, Serge

2018-04-01

Isotope ratio monitoring by 13C NMR spectrometry (irm-13C NMR) provides the complete 13C intramolecular position-specific composition at natural abundance. It represents a powerful tool to track the (bio)chemical pathway which has led to the synthesis of targeted molecules, since it allows Position-specific Isotope Analysis (PSIA). Due to the very small composition range (which represents the range of variation of the isotopic composition of a given nuclei) of 13C natural abundance values (50‰), irm-13C NMR requires a 1‰ accuracy and thus highly quantitative analysis by 13C NMR. Until now, the conventional strategy to determine the position-specific abundance xi relies on the combination of irm-MS (isotopic ratio monitoring Mass Spectrometry) and 13C quantitative NMR. However this approach presents a serious drawback since it relies on two different techniques and requires to measure separately the signal of all the carbons of the analyzed compound, which is not always possible. To circumvent this constraint, we recently proposed a new methodology to perform 13C isotopic analysis using an internal reference method and relying on NMR only. The method combines a highly quantitative 1H NMR pulse sequence (named DWET) with a 13C isotopic NMR measurement. However, the recently published DWET sequence is unsuited for samples with short T1, which forms a serious limitation for irm-13C NMR experiments where a relaxing agent is added. In this context, we suggest two variants of the DWET called Multi-WET and Profiled-WET, developed and optimized to reach the same accuracy of 1‰ with a better immunity towards T1 variations. Their performance is evaluated on the determination of the 13C isotopic profile of vanillin. Both pulse sequences show a 1‰ accuracy with an increased robustness to pulse miscalibrations compared to the initial DWET method. This constitutes a major advance in the context of irm-13C NMR since it is now possible to perform isotopic analysis with high

13C and 15N CP/MAS, 1H-15N SCT CP/MAS and FTIR spectroscopy as tools for qualitative detection of the presence of zwitterionic and non-ionic forms of ansa-macrolide 3-formylrifamycin SV and its derivatives in solid state.

Science.gov (United States)

Przybylski, Piotr; Pyta, Krystian; Klich, Katarzyna; Schilf, Wojciech; Kamieński, Bohdan

2014-01-01

(13)C, (15)N CP/MAS, including (1)H-(13)C and (1)H-(15)N short contact time CP/MAS experiments, and FTIR methods were applied for detailed structural characterization of ansa-macrolides as 3-formylrifamycin SV (1) and its derivatives (2-6) in crystal and in powder forms. Although HPLC chromatograms for 2/CH3 OH and 2/CH3 CCl3 were the same for rifampicin crystals dissolved in respective solvents, the UV-vis data recorded for them were different in 300-375 nm region. Detailed solid state (13)C and (15)N CP/MAS NMR and FTIR studies revealed that rifampicin (2), in contrast to 3-formylrifamycin SV (1) and its amino derivatives (3-6), can occur in pure non-ionic or zwitterionic forms in crystal and in pure these forms or a mixture of them in a powder. Multinuclear CP/MAS and FTIR studies demonstrated also that 3-6 derivatives were present exclusively in pure zwitterionic forms, both in powder and in crystal. On the basis of the solid state NMR and FTIR studies, two conformers of 3-formylrifamycin SV were detected in powder form due to the different orientations of carbonyl group of amide moiety. The PM6 molecular modeling at the semi-empirical level of theory, allowed visualization the most energetically favorable non-ionic and zwitterionic forms of 1-6 antibiotics, strongly stabilized via intramolecular H-bonds. FTIR studies indicated that the originally adopted forms of these type antibiotics in crystal or in powder are stable in standard laboratory conditions in time. The results presented point to the fact that because of a possible presence of two forms of rifampicin (compound 2), quantification of the content of this antibiotic in relevant pharmaceuticals needs caution. Copyright © 2013 John Wiley & Sons, Ltd.

13C and 31P NMR study of gluconeogenesis: utilization of 13C-labeled substrates by perfused liver from streptozotocin-diabetic and untreated rats

International Nuclear Information System (INIS)

Cohen, S.M.

1987-01-01

The metabolism of 13 C-labeled substrates was followed by 13 C and 31 P NMR in perfused liver from the streptozotocin-treated rat model of insulin-dependent diabetes. Comparison was made with perfused liver from untreated littermates, fasted either 24 or 12 h. The major routes of pyruvate metabolism were followed by a 13 C NMR approach that provided for the determination of the metabolic fate of several substances simultaneously. The rate of gluconeogenesis was 2-4-fold greater and β-hydroxybutyrate production was 50% greater in liver from the chronically diabetic rats as compared with the control groups. Large differences in the distribution of 13 C label in hepatic alanine were measured between diabetic and control groups. The biosyntheses of 13 C-labeled glutathione and N-carbamoylaspartate were monitored in time-resolved 13 C NMR spectra of perfused liver. Assignments for the resonances of glutathione and N-carbamoylaspartate were made with the aid of 13 C NMR studies of perchloric acid extracts of the freeze-clamped livers. 13 C NMR spectroscopy of the perfusates provided a convenient, rapid assay of the rate of oxidation of [2- 13 C]ethanol, the hepatic output of [2- 13 ]acetaldehyde, and the accumulation of [2- 13 C]acetate in the perfusate. By 31 P NMR spectroscopy, carbamoyl phosphate was measured in all diabetic livers and an unusual P,P'-diesterified pyrophosphate was observed in one-fourth of the diabetic livers examined. Neither of these phosphorylated metabolites was detected in control liver. Both 13 C and 31 P NMR were useful in defining changes in hepatic metabolism in experimental diabetes

1H-NMR/13C-NMR studies of branched structures in PVC obtained at atmospheric pressure

International Nuclear Information System (INIS)

Braun, D.; Holzer, G.; Hjertberg, T.

1981-01-01

The 1 H-NMR-spectra of raw poly (vinyl cloride) obtained at atmospheric pressure (U-PVC) have revealed the presence of high concentrations of branches. The content of labile chlorine was determined by reaction with phenole in order to estimate the branch points with tertiary chlorine. The branch length of reductively dehalogenated U-PVC by 13 C-NMR analysis have provided evidence for both short chain branches including chloromethyl groups and 2.4-dichloro-n-butyl groups and long chain branching. For a number of U-polymers the total amount of branching ranges from 7.5 to 13.5/1000 C. The 13 C-NMR measurements point to a ratio of methyl/butyl branches of 1:1 and short chains/long chains of 6:1. (orig.)

Structural properties of carbon nanotubes derived from 13C NMR

KAUST Repository

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

2011-01-01

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

Anomalous H/D isotope effect on 35Cl NQR frequencies and H/D isotope effect on 1H MAS NMR spectra in pyrrolidinium p-chlorobenzoate

International Nuclear Information System (INIS)

Nakano, Ryo; Honda, Hisashi; Nakata, Eiichi; Takamizawa, Satoshi; Noro, Sumiko; Kimura, Taiki; Kyo, Shin-shin; Ishimaru, Shin'ichi; Miyake, Ryosuke

2010-01-01

An anomalous isotope effect was observed in the 35 Cl NQR frequency of pyrrolidinium p-chlorobenzoate (C 4 H 8 NH 2 + ·ClC 6 H 4 COO - ) by deuterium substitution of hydrogen atoms which form two kinds of N-H...O type hydrogen bonds. Large negative frequency shifts of the 35 Cl resonance lines, reaching 309 kHz at 77 K and 267 kHz at 293 K, were obtained upon deuteration, although the Cl atom in the molecule formed no hydrogen bonds in the crystal. 1 H MAS NMR lines showed significant changes by the deuterium substitution, while in contrast, small shifts of 13 C CP/MAS NMR signals were obtained. Our measurements of 1 H NMR spin-lattice relaxation times (T 1 ) suggested that the H/D isotope shifts detected from the 35 Cl NQR frequencies and 1 H NMR spectra are due to structural changes rather than molecular dynamics. Single-crystal X-ray diffraction measurements showed two remarkable H/D isotope differences in the molecular arrangements, (1) the N-H length along the crystallographic a axis became 1 pm shorter, and (2) the dihedral angle between benzene and the pyrrolidine ring changed by 1.1(2)deg upon deuteration. Using density functional theory estimations, the anomalous 35 Cl NQR frequency shifts and 1 H MAS NMR line-shape changes could be explained by the dihedral angle change rather than the N-H length difference. (author)

A General Protocol for Temperature Calibration of MAS NMR Probes at Arbitrary Spinning Speeds

Science.gov (United States)

Guan, Xudong; Stark, Ruth E.

2010-01-01

A protocol using 207Pb NMR of solid lead nitrate was developed to determine the temperature of magic-angle spinning (MAS) NMR probes over a range of nominal set temperatures and spinning speeds. Using BioMAS and fastMAS probes with typical sample spinning rates of 8 and 35 kHz, respectively, empirical equations were devised to predict the respective sample temperatures. These procedures provide a straightforward recipe for temperature calibration of any MAS probe. PMID:21036557

C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy

International Nuclear Information System (INIS)

Fossell, E.T.; Hall, F.M.; McDonagh, J.

1991-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-12-31

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

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

Science.gov (United States)

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

2018-07-01

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

Identifying inter-residue resonances in crowded 2D {sup 13}C-{sup 13}C chemical shift correlation spectra of membrane proteins by solid-state MAS NMR difference spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Miao Yimin; Cross, Timothy A. [Florida State University, Department of Chemistry and Biochemistry (United States); Fu Riqiang, E-mail: rfu@magnet.fsu.edu [National High Magnet Field Lab (United States)

2013-07-15

The feasibility of using difference spectroscopy, i.e. subtraction of two correlation spectra at different mixing times, for substantially enhanced resolution in crowded two-dimensional {sup 13}C-{sup 13}C chemical shift correlation spectra is presented. With the analyses of {sup 13}C-{sup 13}C spin diffusion in simple spin systems, difference spectroscopy is proposed to partially separate the spin diffusion resonances of relatively short intra-residue distances from the longer inter-residue distances, leading to a better identification of the inter-residue resonances. Here solid-state magic-angle-spinning NMR spectra of the full length M2 protein embedded in synthetic lipid bilayers have been used to illustrate the resolution enhancement in the difference spectra. The integral membrane M2 protein of Influenza A virus assembles as a tetrameric bundle to form a proton-conducting channel that is activated by low pH and is essential for the viral lifecycle. Based on known amino acid resonance assignments from amino acid specific labeled samples of truncated M2 sequences or from time-consuming 3D experiments of uniformly labeled samples, some inter-residue resonances of the full length M2 protein can be identified in the difference spectra of uniformly {sup 13}C labeled protein that are consistent with the high resolution structure of the M2 (22-62) protein (Sharma et al., Science 330(6003):509-512, 2010)

In vivo NMR analysis of incorporation of [2-13C] glycine into silk fibroin

International Nuclear Information System (INIS)

Asakura, Tetsuo; Nagashima, Mariko; Demura, Makoto; Osanai, Minoru.

1990-01-01

The biosynthetic mechanism of silk fibroin in silkworms, Bombyx mori, is unique because this fibrous protein composed mainly of glycine, alanine and serine is produced very rapidly in large quantity in the posterior silk glands. It is very meaningful to investigate into the biosynthesis of silk protein under nondestructive condition by in vivo NMR and C-13 labeling techniques. The sugar metabolism related to the production of silk fibroin was analyzed by monitoring the change in the C-13 labeled peaks in the NMR spectra for silkworms. In this paper, the monitoring of the 2-(C-13) glycine metabolism in Bombyx mori by the C-13 NMR in vivo is reported. In particular, the in vivo transport of glycine from the midgut to the posterior silk gland was measured, and the rate constants were determined with the course of the peak intensity in the C-13 NMR spectra. It is possible to discuss quantitatively the in vivo production of silk fibroin with these rate constants. The experiment and the results are reported. The in vivo C-13 NMR spectra of a 5 day old, 5th instar larva of Bombyx mori after the oral administration of 2-(C-13) glycine are shown. The significant increase of the peak intensity occurred. (K.I.)

Exploring high-resolution magic angle spinning (HR-MAS) NMR spectroscopy for metabonomic analysis of apples.

Science.gov (United States)

Vermathen, Martina; Marzorati, Mattia; Vermathen, Peter

2012-01-01

Classical liquid-state high-resolution (HR) NMR spectroscopy has proved a powerful tool in the metabonomic analysis of liquid food samples like fruit juices. In this paper the application of (1)H high-resolution magic angle spinning (HR-MAS) NMR spectroscopy to apple tissue is presented probing its potential for metabonomic studies. The (1)H HR-MAS NMR spectra are discussed in terms of the chemical composition of apple tissue and compared to liquid-state NMR spectra of apple juice. Differences indicate that specific metabolic changes are induced by juice preparation. The feasibility of HR-MAS NMR-based multivariate analysis is demonstrated by a study distinguishing three different apple cultivars by principal component analysis (PCA). Preliminary results are shown from subsequent studies comparing three different cultivation methods by means of PCA and partial least squares discriminant analysis (PLS-DA) of the HR-MAS NMR data. The compounds responsible for discriminating organically grown apples are discussed. Finally, an outlook of our ongoing work is given including a longitudinal study on apples.

Lipid bilayer-bound conformation of an integral membrane beta barrel protein by multidimensional MAS NMR

International Nuclear Information System (INIS)

Eddy, Matthew T.; Su, Yongchao; Silvers, Robert; Andreas, Loren; Clark, Lindsay; Wagner, Gerhard; Pintacuda, Guido; Emsley, Lyndon; Griffin, Robert G.

2015-01-01

The human voltage dependent anion channel 1 (VDAC) is a 32 kDa β-barrel integral membrane protein that controls the transport of ions across the outer mitochondrial membrane. Despite the determination of VDAC solution and diffraction structures, a structural basis for the mechanism of its function is not yet fully understood. Biophysical studies suggest VDAC requires a lipid bilayer to achieve full function, motivating the need for atomic resolution structural information of VDAC in a membrane environment. Here we report an essential step toward that goal: extensive assignments of backbone and side chain resonances for VDAC in DMPC lipid bilayers via magic angle spinning nuclear magnetic resonance (MAS NMR). VDAC reconstituted into DMPC lipid bilayers spontaneously forms two-dimensional lipid crystals, showing remarkable spectral resolution (0.5–0.3 ppm for 13 C line widths and <0.5 ppm 15 N line widths at 750 MHz). In addition to the benefits of working in a lipid bilayer, several distinct advantages are observed with the lipid crystalline preparation. First, the strong signals and sharp line widths facilitated extensive NMR resonance assignments for an integral membrane β-barrel protein in lipid bilayers by MAS NMR. Second, a large number of residues in loop regions were readily observed and assigned, which can be challenging in detergent-solubilized membrane proteins where loop regions are often not detected due to line broadening from conformational exchange. Third, complete backbone and side chain chemical shift assignments could be obtained for the first 25 residues, which comprise the functionally important N-terminus. The reported assignments allow us to compare predicted torsion angles for VDAC prepared in DMPC 2D lipid crystals, DMPC liposomes, and LDAO-solubilized samples to address the possible effects of the membrane mimetic environment on the conformation of the protein. Concluding, we discuss the strengths and weaknesses of the reported

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

Science.gov (United States)

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

2014-07-01

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

Detailed 1H and 13C NMR spectral data assignment for two dihydrobenzofuran neolignans

International Nuclear Information System (INIS)

Medeiros, Talita C.T.; Dias, Herbert J.; Crotti, Antônio E.M.

2016-01-01

In this work we present a complete proton ( 1 H) and carbon 13 ( 13 C) nuclear magnetic resonance (NMR) spectral analysis of two synthetic dihydrofuran neolignans (±)-trans-dehydrodicoumarate dimethyl ester and (±)-trans-dehydrodiferulate dimethyl ester. Unequivocal assignments were achieved by 1 H NMR, proton decoupled 13 C ( 13 C{ 1 H}) NMR spectra, gradient-selected correlation spectroscopy (gCOSY), J-resolved, gradient-selected heteronuclear multiple quantum coherence (gHMQC), gradient-selected heteronuclear multiple bond coherence (gHMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. All hydrogen coupling constants were measured, clarifying all the hydrogen signals multiplicities. Computational methods were also used to simulate the 1 H and 13 C chemical shifts and showed good agreement with the trans configuration of the substituents at C 7 and C 8 . (author)

Structural characterization of supramolecular assemblies by {sup 13}C spin dilution and 3D solid-state NMR

Energy Technology Data Exchange (ETDEWEB)

Habenstein, Birgit; Loquet, Antoine; Giller, Karin; Becker, Stefan; Lange, Adam, E-mail: adla@nmr.mpibpc.mpg.de [Max Planck Institute for Biophysical Chemistry, Department of NMR-based Structural Biology (Germany)

2013-01-15

{sup 13}C spin diluted protein samples can be produced using [1-{sup 13}C] and [2-{sup 13}C]-glucose (Glc) carbon sources in the bacterial growth medium. The {sup 13}C spin dilution results in favorable {sup 13}C spectral resolution and polarization transfer behavior. We recently reported the combined use of [1-{sup 13}C]- and [2-{sup 13}C]-Glc labeling to facilitate the structural analysis of insoluble and non-crystalline biological systems by solid-state NMR (ssNMR), including sequential assignment, detection of long-range contacts and structure determination of macromolecular assemblies. In solution NMR the beneficial properties of sparsely labeled samples using [2-{sup 13}C]-glycerol ({sup 13}C labeled C{alpha} sites on a {sup 12}C diluted background) have recently been exploited to provide a bi-directional assignment method (Takeuchi et al. in J Biomol NMR 49(1):17-26, 2011 ). Inspired by this approach and our own recent results using [2-{sup 13}C]-Glc as carbon sources for the simplification of ssNMR spectra, we present a strategy for a bi-directional sequential assignment of solid-state NMR resonances and additionally the detection of long-range contacts using the combination of {sup 13}C spin dilution and 3D NMR spectroscopy. We illustrate our results with the sequential assignment and the collection of distance restraints on an insoluble and non-crystalline supramolecular assembly, the Salmonella typhimurium type III secretion system needle.

Heteronuclear 2D (1H-13C) MAS NMR Resolves the Electronic Structure of Coordinated Histidines in Light-Harvesting Complex II: Assessment of Charge Transfer and Electronic Delocalization Effect

International Nuclear Information System (INIS)

Matysik, Joerg; Boer, Ido de; Gast, Peter; Gorkom, Hans J. van; Groot, Huub J.M. de

2004-01-01

In a recent MAS NMR study, two types of histidine residues in the light-harvesting complex II (LH2) of Rhodopseudomonas acidophila were resolved: Type 1 (neutral) and Type 2 (positively charged) (Alia et al. J. Am. Chem. Soc.). The isotropic 13 C shifts of histidines coordinating to B850 BChl a are similar to fully positively charged histidine, while the 15 N shift anisotropy shows a predominantly neutral character. In addition the possibility that the ring currents are quenched by overlap in the superstructure of the complete ring of 18 B850 molecules in the LH2 complex could not be excluded. In the present work, by using two-dimensional heteronuclear ( 1 H- 13 C) dipolar correlation spectroscopy with phase-modulated Lee-Goldburg homonuclear 1 H decoupling applied during the t 1 period, a clear and unambiguous assignment of the protons of histidine interacting with the magnesium of a BChl a molecule is obtained and a significant ring current effect from B850 on the coordinating histidine is resolved. Using the ring current shift on 1 H, we refine the 13 C chemical shift assignment of the coordinating histidine and clearly distinguish the electronic structure of coordinating histidines from that of fully positively charged histidine. The DFT calculations corroborate that the coordinating histidines carry ∼0.2 electronic equivalent of positive charge in LH2. In addition, the data indicate that the ground state electronic structures of individual BChl a/His complexes is largely independent of supermolecular π interactions in the assembly of 18 B850 ring in LH2

Characterization of water in hydrated Bombyx mori silk fibroin fiber and films by 2H NMR relaxation and 13C solid state NMR.

Science.gov (United States)

Asakura, Tetsuo; Isobe, Kotaro; Kametani, Shunsuke; Ukpebor, Obehi T; Silverstein, Moshe C; Boutis, Gregory S

2017-03-01

The mechanical properties of Bombyx mori silk fibroin (SF), such as elasticity and tensile strength, change remarkably upon hydration. However, the microscopic interaction with water is not currently well understood on a molecular level. In this work, the dynamics of water molecules interacting with SF was studied by 2 H solution NMR relaxation and exchange measurements. Additionally, the conformations of hydrated [3- 13 C]Ala-, [3- 13 C]Ser-, and [3- 13 C]Tyr-SF fibers and films were investigated by 13 C DD/MAS NMR. Using an inverse Laplace transform algorithm, we were able to identify four distinct components in the relaxation times for water in SF fiber. Namely, A: bulk water outside the fiber, B: water molecules trapped weakly on the surface of the fiber, C: bound water molecules located in the inner surface of the fiber, and D: bound water molecules located in the inner part of the fiber were distinguishable. In addition, four components were also observed for water in the SF film immersed in methanol for 30s, while only two components for the film immersed in methanol for 24h. The effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and non-crystalline domains of 13 C selectively labeled SF, respectively, could be determined independently. Our measurements provide new insight relating the characteristics of water and the hydration structure of silk, which are relevant in light of current interest in the design of novel silk-based biomaterials. The mechanical properties of Bombyx mori silk fibroin (SF) change remarkably upon hydration. However, the microscopic interaction between SF and water is not currently well understood on a molecular level. We were able to identify four distinct components in the relaxation times for water in SF fiber by 2 H solution NMR relaxation and exchange measurements. In addition, the effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and

1H HR-MAS NMR and S180 cells: metabolite assignment and evaluation of pulse sequence

International Nuclear Information System (INIS)

Oliveira, Aline L. de; Martinelli, Bruno César B.; Lião, Luciano M.; Pereira, Flávia C.; Silveira-Lacerda, Elisangela P.; Alcantara, Glaucia B.

2014-01-01

High resolution magic angle spinning 1 H nuclear magnetic resonance spectroscopy (HR-MAS NMR) is a useful technique for evaluation of intact cells and tissues. However, optimal NMR parameters are crucial in obtaining reliable results. To identify the key steps for the optimization of HR-MAS NMR parameters, we assessed different pulse sequences and NMR parameters using sarcoma 180 (S180) cells. A complete assignment of the metabolites of S180 is given to assist future studies. (author)

APPLICATION OF A C-13 NMR TOPOLOGICAL MODEL TO THE STRUCTURE ELUCIDATION OF ORGANIC COMPOUNDS

Institute of Scientific and Technical Information of China (English)

袁身刚; 彭琛; 郑崇直

1992-01-01

This paper presents an approach which can elucidate automatically the structures of simple organic compounds from their C-13 NMR spectral data by using a computer. Based on a substructure/C-13 NMR chemical shift topological correlation model, the approach deduces the candidate substructures and the constraints for the substructure assembling from the molecular formula and C-13 NMR spectral data. Then, candidate structures are generated under these constraints by assembling the candidate substructures in a partial superposition manner. Candidate substructures or structures are evaluated once they are generated in order to eliminate those conflicting with the original data as early as possible. The evaluation of a (sub)structure is mainly carried out by simulating its C-13 NMR (sub) spectrum, which is again based on the model, and comparing the simulated spectrum with the original data.

Carbon-13 NMR of flavinoids

International Nuclear Information System (INIS)

Agrawal, P.K.

1989-01-01

The present book has been written with the objective of introducing the organic chemists with the conceptual and experimental basis required for interpretation of 13 C NMR spectra of a flavonoid and to a discussion of general usefulness of the technique in solving flavonoid structural problem. After a brief general introduction to the essential aspects of flavonoids and 13 C NMR spectroscopy, considerable emphasis has been placed in chapter 2 on the various experimental methods and the interpretation of spectral details which enable individual resonance lines to be associated with the appropriate carbons in a molecule. The whole bulk of the literature, published on 13 C NMR of flavonoids in the major journals upto 1986 alongwith some recent references of 1987 has been classified in several categories such as: flavonoids, isflavonoids, other flavonoids, flavonoid glycosides, chalconoids and flavanoids. Each category constitutes a chapter. Finally the last chapter is devoted largely to a discussion for the differentiation of various categories and subcategories of flavonoids and for the establishment of aromatic substitution pattern in these compounds. It should be emphasized that the book is a data book and only concerned with the actual analysis of 13 C NMR spectra, thus a reasonable familiarity with basic instrumentation of 13 C NMR and general pattern of nuclear chemical shifts has been assumed. (author). refs.; figs.; tabs

Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

Science.gov (United States)

Tossell, J. A.

1995-04-01

13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

Total assignment of 1 H and 13 C NMR of Cordiachrome C, a terpenoid benzoquinone from Cordia trichotoma

International Nuclear Information System (INIS)

Alencar, Jane Eire; Pessoa, Otilia Deusdenia Loiola; Lemos, Tlema Leda Gomes de; Silveira, Edilberto Rocha; Braz Filho, Raimundo

1999-01-01

1 D and 2 D NMR techniques were applied for establishing of the complete assignment of hydrogen and carbon-13 NMR of cordiachrome C. Th results were also used to confirm 1 H NMR data already published, as well as to define the relative stereochemistry, which has not been completely established for cordiachrome C, previously isolated from C. millenii

1H-detected MAS solid-state NMR experiments enable the simultaneous mapping of rigid and dynamic domains of membrane proteins

Science.gov (United States)

Gopinath, T.; Nelson, Sarah E. D.; Veglia, Gianluigi

2017-12-01

Magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy is emerging as a unique method for the atomic resolution structure determination of native membrane proteins in lipid bilayers. Although 13C-detected ssNMR experiments continue to play a major role, recent technological developments have made it possible to carry out 1H-detected experiments, boosting both sensitivity and resolution. Here, we describe a new set of 1H-detected hybrid pulse sequences that combine through-bond and through-space correlation elements into single experiments, enabling the simultaneous detection of rigid and dynamic domains of membrane proteins. As proof-of-principle, we applied these new pulse sequences to the membrane protein phospholamban (PLN) reconstituted in lipid bilayers under moderate MAS conditions. The cross-polarization (CP) based elements enabled the detection of the relatively immobile residues of PLN in the transmembrane domain using through-space correlations; whereas the most dynamic region, which is in equilibrium between folded and unfolded states, was mapped by through-bond INEPT-based elements. These new 1H-detected experiments will enable one to detect not only the most populated (ground) states of biomacromolecules, but also sparsely populated high-energy (excited) states for a complete characterization of protein free energy landscapes.

13C NMR for the assessment of human brain glucose metabolism in vivo

International Nuclear Information System (INIS)

Beckman, N.; Seelig, J.; Turkalj, I.; Keller, U.

1991-01-01

Proton-decoupled 13 C NMR spectra of the human head were obtained during hyperglycemic glucose clamping using intravenous infusions of [1- 13 C]glucose in normal volunteers. In addition to 13 C signals of mobile lipids, a variety of new metabolite resonances could be resolved for the first time in the human brain. At an enrichment level of 20% [1- 13 C]glucose, the signals of α- and β-glucose at 92.7 and 96.6 ppm, respectively, could be detected in the human brain after only an infusion period of 15 minutes. The spatial localization of the different regions of interest was confirmed by 13 C NMR spectroscopic imaging with a time resolution of 9 minutes. Increasing the enrichment level to 99% [1- 13 C]glucose not only improved the time resolution but allowed the detection of metabolic breakdown products of [1- 13 C]glucose. The time course of 13 C label incorporation into the C 2 , C 3 , and C 4 resonances of glutamate/glutamine and into lactate could be recorded in the human brain. These results suggest the possibility of obtaining time-resolved, spatially selective, and chemically specific information on the human body

Surface Characterization of Some Novel Bonded Phase Packing Materials for HPLC Columns Using MAS-NMR Spectroscopy

Directory of Open Access Journals (Sweden)

Jude Abia

2015-03-01

Full Text Available Information on the surface properties of three novel chemically bonded phase packing materials for High performance liquid chromatography (HPLC were obtained using spectra obtained by solid state cross-polarization (CP magic-angle spinning (MAS nuclear magnetic resonance (NMR spectroscopic experiments for the 29Si, and 13C nuclei. These packing materials were: Cogent bidentate C18 bonded to type-C silica, hybrid packing materials XTerra MS C18, and XBridge Prep. C18. The spectra obtained using cross-polarization magic angle spinning (CP-MAS on the Cogent bidentate C18 bonded to type-C silica show the surface to be densely populated with hydride groups (Si-H, with a relative surface coverage exceeding 80%. The hybrid packing materials XTerra and XBridge gave spectra that reveal the silicon atoms to be bonded to organic moieties embedded in the molecular structure of these materials with over 90% of the alkyl silicon atoms found within the completely condensed silicon environments. The hydrolytic stability of these materials were investigated in acidic aqueous solutions at pHs of 7.0 and 3.0, and it was found that while the samples of XTerra and XBridge were not affected by hydrolysis at this pH range, the sample of Cogent lost a significant proportion of its Si-H groups after five days of treatment in acidic aqueous solution.

13C NMR spectra and bonding situation of the B-C bond in alkynylboranes

International Nuclear Information System (INIS)

Yamamoto, Yoshinori; Moritani, Ichiro

1975-01-01

13 C NMR spectra of boron substituted alkynes reveal that the β-carbon is deshielded by ca. 21 ppm by a B(O-n-C 4 H 9 ) 2 group. This clearly indicates the presence of a B-C π-bonding in alkynylboranes. (auth.)

{sup 1}H HR-MAS NMR and S180 cells: metabolite assignment and evaluation of pulse sequence

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Aline L. de; Martinelli, Bruno César B.; Lião, Luciano M. [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil). Instituto de Química. Lab. de RMN; Pereira, Flávia C.; Silveira-Lacerda, Elisangela P. [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil). Instituto de Ciências Biológicas. Laboratório Genética Molecular e Citogenética; Alcantara, Glaucia B., E-mail: glaucia.alcantara@ufms.br [Universidade Federal de Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Inst. de Química

2014-07-01

High resolution magic angle spinning {sup 1}H nuclear magnetic resonance spectroscopy (HR-MAS NMR) is a useful technique for evaluation of intact cells and tissues. However, optimal NMR parameters are crucial in obtaining reliable results. To identify the key steps for the optimization of HR-MAS NMR parameters, we assessed different pulse sequences and NMR parameters using sarcoma 180 (S180) cells. A complete assignment of the metabolites of S180 is given to assist future studies. (author)

13C NMR Chemical Shifts of the Triclinic and Monoclinic Crystal forms of Valinomycin

International Nuclear Information System (INIS)

Kameda, Tsunenori; McGeorge, Gary; Orendt, Anita M.; Grant, David M.

2004-01-01

Two different crystalline polymorphs of valinomycin, the triclinic and monoclinic forms, have been studied by high resolution, solid state 13 C CP-MAS NMR spectroscopy. Although the two polymorphs of the crystal are remarkably similar, there are distinct differences in the isotropic chemical shifts between the two spectra. For the triclinic form, the carbon chemical shift tensor components for the alpha carbons adjacent to oxygen in the lactic acid and hydroxyisovaleric acid residues and the ester carbonyls of the valine residue were obtained using the FIREMAT experiment. From the measured components, it was found that the behavior of the isotropic chemical shift, δ iso , for valine residue ester carbonyl carbons is predominately influenced by the intermediate component, δ 22 . Additionally it was found that the smallest shift component, δ 33 , for the L-lactic acid (L-Lac) and D-α-hydroxyisovaleric acid (D-Hyi) C α -O carbon was significantly displaced depending upon the nature of individual amino acid residues, and it is the δ 33 component that governs the behavior of δ iso in these alpha carbons

Out-and-back {sup 13}C-{sup 13}C scalar transfers in protein resonance assignment by proton-detected solid-state NMR under ultra-fast MAS

Energy Technology Data Exchange (ETDEWEB)

Barbet-Massin, Emeline; Pell, Andrew J. [University of Lyon, CNRS/ENS Lyon/UCB Lyon 1, Centre de RMN a Tres Hauts Champs (France); Jaudzems, Kristaps [Latvian Institute of Organic Synthesis (Latvia); Franks, W. Trent; Retel, Joren S. [Leibniz-Institut fuer Molekulare Pharmakologie (Germany); Kotelovica, Svetlana; Akopjana, Inara; Tars, Kaspars [Biomedical Research and Study Center (Latvia); Emsley, Lyndon [University of Lyon, CNRS/ENS Lyon/UCB Lyon 1, Centre de RMN a Tres Hauts Champs (France); Oschkinat, Hartmut [Leibniz-Institut fuer Molekulare Pharmakologie (Germany); Lesage, Anne; Pintacuda, Guido, E-mail: guido.pintacuda@ens-lyon.fr [University of Lyon, CNRS/ENS Lyon/UCB Lyon 1, Centre de RMN a Tres Hauts Champs (France)

2013-08-15

We present here {sup 1}H-detected triple-resonance H/N/C experiments that incorporate CO-CA and CA-CB out-and-back scalar-transfer blocks optimized for robust resonance assignment in biosolids under ultra-fast magic-angle spinning (MAS). The first experiment, (H)(CO)CA(CO)NH, yields {sup 1}H-detected inter-residue correlations, in which we record the chemical shifts of the CA spins in the first indirect dimension while during the scalar-transfer delays the coherences are present only on the longer-lived CO spins. The second experiment, (H)(CA)CB(CA)NH, correlates the side-chain CB chemical shifts with the NH of the same residue. These high sensitivity experiments are demonstrated on both fully-protonated and 100 %-H{sup N} back-protonated perdeuterated microcrystalline samples of Acinetobacter phage 205 (AP205) capsids at 60 kHz MAS.

Ab initio/GIAO-CCSD(T) (13)C NMR study of the rearrangement and dynamic aspects of rapidly equilibrating tertiary carbocations, C6H13(+) and C7H15(+).

Science.gov (United States)

Olah, George A; Prakash, G K Surya; Rasul, Golam

2016-01-05

The rearrangement pathways of the equilibrating tertiary carbocations, 2,3-dimethyl-2-butyl cation (C6H13(+), 1), 2,3,3-trimethyl-2-butyl cation (C7H15(+), 5) and 2,3-dimethyl-2-pentyl cation (C7H15(+), 8 and 9) were investigated using the ab initio/GIAO-CCSD(T) (13)C NMR method. Comparing the calculated and experimental (13)C NMR chemical shifts of a series of carbocations indicates that excellent prediction of δ(13)C could be achieved through scaling. In the case of symmetrical equilibrating cations (1 and 5) the Wagner-Meerwein 1,2-hydride and 1,2-methide shifts, respectively, produce the same structure. This indicates that the overall (13)C NMR chemical shifts are conserved and independent of temperature. However, in the case of unsymmetrical equilibrating cations (8 and 9) the Wagner-Meerwein shift produces different tertiary structures, which have slightly different thermodynamic stabilities and, thus, different spectra. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level structure 8 is only 90 calories/mol more stable than structure 9. Based on computed (13)C NMR chemical shift calculations, mole fractions of these isomers were determined by assuming the observed chemical shifts are due to the weighted average of the chemical shifts of the static ions. © 2015 Wiley Periodicals, Inc.

13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas

Directory of Open Access Journals (Sweden)

Qiang Wei

2018-02-01

Full Text Available The structure evolution characteristics of high-organic-sulfur (HOS coals with a wide range of ranks from typical Chinese areas were investigated using 13C-CP/MAS NMR. The results indicate that the structure parameters that are relevant to coal rank include CH3 carbon (fal*, quaternary carbon, CH/CH2 carbon + quaternary carbon (falH, aliphatic carbon (falC, protonated aromatic carbon (faH, protonated aromatic carbon + aromatic bridgehead carbon (faH+B, aromaticity (faCP, and aromatic carbon (farC. The coal structure changed dramatically in the first two coalification jumps, especially the first one. A large number of aromatic structures condensed, and aliphatic structures rapidly developed at the initial stage of bituminous coal accompanied by remarkable decarboxylation. Compared to ordinary coals, the structure evolution characteristics of HOS coals manifest in three ways: First, the aromatic CH3 carbon, alkylated aromatic carbon (faS, aromatic bridgehead carbon (faB, and phenolic ether (faP are barely relevant to rank, and abundant organic sulfur has an impact on the normal evolution process of coal. Second, the average aromatic cluster sizes of some super-high-organic-sulfur (SHOS coals are not large, and the extensive development of cross bonds and/or bridged bonds form closer connections among the aromatic fringes. Moreover, sulfur-containing functional groups are probably significant components in these linkages. Third, a considerable portion of “oxygen-containing functional groups” in SHOS coals determined by 13C-NMR are actually sulfur-containing groups, which results in the anomaly that the oxygen-containing structures increase with coal rank.

13C-NMR spectra and bonding situation in ketenimines

International Nuclear Information System (INIS)

Firl, J.; Runge, W.; Hartmann, W.; Utikal, H.P.

1975-01-01

13 C-NMR spectra of a series of substituted ketenimines are reported. The terminal carbon resonances are found at unusual high fields between delta 37 and 78, while the central carbon signals appear around delta 189 - 196. On the basis of these results, the bonding situation in ketenimines has been discussed. (auth.)

13C nuclear magnetic resonance data of lanosterol derivatives—Profiling the steric topology of the steroid skeleton via substituent effects on its 13C NMR

Science.gov (United States)

Dias, Jerry Ray; Gao, Hongwu

2009-12-01

The 13C NMR spectra of over 24 tetracyclic triterpenoid derivatives have been structurally analyzed. The 13C NMR chemical shifts allow one to probe the steric topology of the rigid steroid skeleton and inductive effects of its substituents. Use of deuterium labeling in chemical shift assignment and B-ring aromatic terpenoids are also featured.

Detailed {sup 1}H and {sup 13}C NMR spectral data assignment for two dihydrobenzofuran neolignans

Energy Technology Data Exchange (ETDEWEB)

Medeiros, Talita C.T.; Dias, Herbert J.; Crotti, Antônio E.M., E-mail: millercrotti@ffclrp.usp.br [Universidade de São Paulo (USP), Ribeirão Preto, SP (Brazil). Faculdade de Filosofia, Ciências e Letras. Departamento de Química

2016-07-01

In this work we present a complete proton ({sup 1}H) and carbon 13 ({sup 13}C) nuclear magnetic resonance (NMR) spectral analysis of two synthetic dihydrofuran neolignans (±)-trans-dehydrodicoumarate dimethyl ester and (±)-trans-dehydrodiferulate dimethyl ester. Unequivocal assignments were achieved by 1 H NMR, proton decoupled {sup 13}C ({sup 13}C{"1H}) NMR spectra, gradient-selected correlation spectroscopy (gCOSY), J-resolved, gradient-selected heteronuclear multiple quantum coherence (gHMQC), gradient-selected heteronuclear multiple bond coherence (gHMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. All hydrogen coupling constants were measured, clarifying all the hydrogen signals multiplicities. Computational methods were also used to simulate the {sup 1}H and {sup 13}C chemical shifts and showed good agreement with the trans configuration of the substituents at C{sub 7} and C{sub 8}. (author)

Detection of human muscle glycogen by natural abundance 13C NMR

International Nuclear Information System (INIS)

Avison, M.J.; Rothman, D.L.; Nadel, E.; Shulman, R.G.

1988-01-01

Natural abundance 13 C nuclear magnetic resonance spectroscopy was used to detect signals from glycogen in the human gastrocnemius muscle. The reproducibility of the measurement was demonstrated, and the ability to detect dynamic changes was confirmed by measuring a decrease in muscle glycogen levels after exercise and its subsequent repletion. Single frequency gated 1 H decoupling was used to obtain decoupled natural abundance 13 C NMR spectra of the C-1 position of muscle glycogen

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...

1 H MAS NMR study of structure of hybrid siloxane-based networks and the interaction with quartz filler

Czech Academy of Sciences Publication Activity Database

Brus, Jiří; Škrdlantová, M.

2001-01-01

Roč. 281, 1-3 (2001), s. 61-71 ISSN 0022-3093 R&D Projects: GA ČR GA203/98/P290; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4050913 Keywords : hybrid siloxane networks * 1 H MAS NMR spectroscopy * hydrogen bonds Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.363, year: 2001

Metabolic pathways for ketone body production. 13C NMR spectroscopy of rat liver in vivo using 13C-multilabeled fatty acids

International Nuclear Information System (INIS)

Pahl-Wostl, C.; Seelig, J.

1986-01-01

The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with 13 C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of 13 C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the 13 C signal intensities were enhanced by using doubly labeled [1,3- 13 C]butyrate as a substrate. Different 13 C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The 13 C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of 13 C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded β-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. 13 C-labeled glucose could be detected in vivo in the liver of diabetic rats

Determination of fructose metabolic pathways in normal and fructose-intolerant children: A 13C NMR study using [U-13C]fructose

International Nuclear Information System (INIS)

Gopher, A.; Lapidot, A.; Vaisman, N.; Mandel, H.

1990-01-01

An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-[U- 13 C]fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of 13 C NMR spectra of plasma glucose. Significantly lower values (∼3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from 13 C NMR measurement of plasma [ 13 C]glucose isotopomer populations. The finding of isotopomer populations of three adjacent 13 C atoms at glucose C-4 ( 13 C 3 - 13 C 4 - 13 C 5 ) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only ∼50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of [ 13 C]glucose formation from a trace amount of [U- 13 C]fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism

/sup 13/C NMR spectra and electron conduction in 4-substituted diphenylamines

Energy Technology Data Exchange (ETDEWEB)

Filimonov, V.D.; Kogan, R.M.; Tverdokhlebova, N.E.; Shcherbakov, V.V.; Kushnarev, D.F.; Kalabin, G.A.

1986-07-10

The /sup 13/C NMR spectra were recorded for a series of 4-X-diphenylamines, and correlations equations relating the /sup 13/C NMR chemical shifts of the C/sup 1/ and C/sup 4/ positions to the electronic characteristics of the substituent X were obtained. It was established that the conduction of the substituted ring in the 4-X-diphenylamines is practically the same as in 4-X-biphenyls. Joint analysis of the spectral characteristics of the diphenylamines, biphenyls, N-substituted anilines, and carbazoles made it possible to conclude that the increased transmission characteristics of the diphenylamines are determined by the conformational mobility of the two benzene rings and by the unidirectional effect of changes in the introduction and resonance factors with variation in the substituent X.

{sup 13} C-NMR of mesquite gum

Energy Technology Data Exchange (ETDEWEB)

Andrade, Cristina T; Garcia, Rosangela B [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas

1992-12-31

Mesquite and guar gums are galactomannans extracted from the seeds of Proposis Juliflora and Cyamopsis tetragonolobus, respectively. An experimental sample of mesquite gum and a commercial sample of guar gum were partially depolymerized by ultrasonic radiation and the produce analysed by high resolution {sup 13} C-NMR spectroscopy. The different carbon lines were resolved and their assignments were done as those reported in the literature. The galactose to mannose ratios (G/M) were estimated from the relative peak areas of the C-1 lines as G/M=61 for mesquite and G/M=0.54 for guar gum. The next nearest-neighbour probabilities (diad frequencies) of the D-galactosyl substitution to the D-mannose backbone were evaluated by integrating C-4 mannose splitted peaks. (author) 9 refs., 2 figs., 2 tabs.

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

Directory of Open Access Journals (Sweden)

Monica Ferro

2017-01-01

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

13C NMR and EPR spectroscopic evaluation of oil shale mined soil recuperation

International Nuclear Information System (INIS)

Santos, J.V. dos; Mangrich, A.S.; Pereira, B.F.; Pillon, C.N.; Bonagamba, T.J.

2013-01-01

In this work, native forest soil (NFS) organic matter (SOM) sample and SOM samples from a neighboring forest soil area of an oil shale mine which is being rehabilitated for thirty years (RFS) were analyzed. X-band electron paramagnetic resonance (EPR) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopies were used to evaluate the soil reclamation of the Brazilian oil shale mining process. Two-dimensional heterospectral correlation studies of the results obtained from EPRand 13 C NMR were used to obtain information about SOM structures and their interactions with residual paramagnetic metal ion. The signal of the residual metallic oxycation, VO 2+ correlated positively with uronic acid-type hydrophilic organic structures, determined from the 13 C NMR spectra, and correlated negatively with the organic free radical (OFR) signal associated with oxygen atoms (g = 2.0042). The hydrophobic aromatic structures correlate positively with the EPR OFR signal associated with carbon atoms (g = 2.0022). The data from the two spectroscopic magnetic techniques show that the used recuperation process is effective. (author)

Combined chemometric analysis of (1)H NMR, (13)C NMR and stable isotope data to differentiate organic and conventional milk.

Science.gov (United States)

Erich, Sarah; Schill, Sandra; Annweiler, Eva; Waiblinger, Hans-Ulrich; Kuballa, Thomas; Lachenmeier, Dirk W; Monakhova, Yulia B

2015-12-01

The increased sales of organically produced food create a strong need for analytical methods, which could authenticate organic and conventional products. Combined chemometric analysis of (1)H NMR-, (13)C NMR-spectroscopy data, stable-isotope data (IRMS) and α-linolenic acid content (gas chromatography) was used to differentiate organic and conventional milk. In total 85 raw, pasteurized and ultra-heat treated (UHT) milk samples (52 organic and 33 conventional) were collected between August 2013 and May 2014. The carbon isotope ratios of milk protein and milk fat as well as the α-linolenic acid content of these samples were determined. Additionally, the milk fat was analyzed by (1)H and (13)C NMR spectroscopy. The chemometric analysis of combined data (IRMS, GC, NMR) resulted in more precise authentication of German raw and retail milk with a considerably increased classification rate of 95% compared to 81% for NMR and 90% for IRMS using linear discriminate analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

13C and 31P NMR studies of myocardial metabolism

International Nuclear Information System (INIS)

Laughlin, M.R.

1988-01-01

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

A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

International Nuclear Information System (INIS)

Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jorgen

2006-01-01

Recent 27 Al MAS NMR studies of hydrated Portland cements and calcium-silicate-hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known aluminate species in hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered aluminate hydrate which contains Al(OH) 6 3- or O x Al(OH) 6-x (3+x)- units. The formation of the new aluminate hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70-90 o C. From the experiments in this work it is proposed that the new aluminate hydrate is either an amorphous/disordered aluminate hydroxide or a calcium aluminate hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed

13C-NMR chemical shift databases as a quick tool to evaluate structural models of humic substances

DEFF Research Database (Denmark)

Nyrop Albers, Christian; Hansen, Poul Erik

2010-01-01

Models for humic and fulvic acids are discussed based on 13C liquid state NMR spectra combined with results from elemental analysis and titration studies. The analysis of NMR spectra is based on a full reconstruction of the NMR spectrum done with help of 13C-NMR data bases by adding up chemical...... side missing structural elements in the models can be suggested. A number of proposed structures for humic and fulvic acids are discussed based on the above analysis....

Total assignment of {sup 1} H and {sup 13} C NMR of Cordiachrome C, a terpenoid benzoquinone from Cordia trichotoma

Energy Technology Data Exchange (ETDEWEB)

Alencar, Jane Eire; Pessoa, Otilia Deusdenia Loiola; Lemos, Tlema Leda Gomes de; Silveira, Edilberto Rocha [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Quimica Organica e Inorganica; Braz Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Setor de Quimica de Produtos Naturais

1999-05-01

1 D and 2 D NMR techniques were applied for establishing of the complete assignment of hydrogen and carbon-13 NMR of cordiachrome C. Th results were also used to confirm {sup 1} H NMR data already published, as well as to define the relative stereochemistry, which has not been completely established for cordiachrome C, previously isolated from C. millenii.

Intracellular PHB conversion in a type II methanotroph studied by 13 C NMR

NARCIS (Netherlands)

Vecherskaya, M.; Dijkema, C.; Stams, A.J.M.

2001-01-01

Poly-g-hydroxybutyrate (PHB) formation under aerobic conditions via incorporation of [13C-2]acetate as a cosubstrate and its intracellular degradation under anaerobic conditions in a Type II methanotroph was studied by 13C NMR. During PHB synthesis in the presence of labelled acetate, low levels of

Improved background suppression in 1H MAS NMR using composite pulses

Science.gov (United States)

Odedra, Smita; Wimperis, Stephen

2012-08-01

A well known feature of 1H MAS NMR spectroscopy, particularly of solids where the concentration of 1H nuclei is low, is the presence in the spectrum of a significant broad "background" signal arising from 1H nuclei that are outside the MAS rotor and radiofrequency coil, probably located on the surfaces of the static components of the probehead. A popular method of suppressing this unwanted signal is the "depth pulse" method, consisting of a 90° pulse followed by one or two 180° pulses that are phase cycled according to the "Exorcycle" scheme, which removes signal associated with imperfect 180° pulses. Consequently, only spins in the centre of the radiofrequency coil contribute to the 1H MAS spectrum, while those experiencing a low B1 field outside the coil are suppressed. Although very effective at removing background signal from the spectrum, one drawback with this approach is that significant loss of the desired signal from the sample also occurs. Here we investigate the 1H background suppression problem and, in particular, the use of novel antisymmetric passband composite pulses to replace the simple pulses in a depth pulse experiment. We show that it is possible to improve the intensity of the 1H signals of interest while still maintaining effective background suppression. We expect that these results will be relevant to 1H MAS NMR studies of, for example, nominally perdeuterated biological samples or nominally anhydrous inorganic materials.

Unified integration intervals for the structural characterization of oil, coal or fractions there of by 1h NMR and 13c NMR

International Nuclear Information System (INIS)

Avella, Eliseo; Fierro, Ricardo

2010-01-01

Based on an analysis of publications reported between 1972 and 2006, it became clear that there are inaccuracies in the limits of the ranges of integration that the authors assigned to signals in nuclear magnetic resonance (NMR) to the structural characterization of petroleum, coals and their derived fractions, from their hydrogen (1H NMR) and carbon (13C NMR) spectra. Consequently, consolidated limits were determined for the integration of 1H NMR spectra and 13C NMR of these samples using a statistical treatment applied to the limits of integration intervals already published. With these unified limits, correlation NMR charts were developed that are useful for the allocation of the integral at such intervals, and at smaller intervals defined in terms of the intersection between different assignments. Also raised equations needed to establish the integral attributable to specific fragments in an attempt to make a more accurate structural characterization from NMR spectra of oil, coal or fractions derived.

Cyclohexanecarbonitriles: Assigning Configurations at Quaternary Centers From 13C NMR CN Chemical Shifts.1

Science.gov (United States)

Wei, Guoqing

2009-01-01

13C NMR chemical shifts of the nitrile carbon in cyclohexanecarbonitriles directly correlate with the configuration of the quaternary, nitrile-bearing stereocenter. Comparing 13C NMR chemical shifts for over 200 cyclohexanecarbonitriles reveals that equatorially oriented nitriles resonate 3.3 ppm downfield, on average, from their axial counterparts. Pairs of axial/equatorial diastereomers varying only at the nitrile-bearing carbon consistently exhibit downfield shifts of δ 0.4–7.2 for the equatorial nitrile carbon, even in angularly substituted decalins and hydrindanes. PMID:19348434

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

Science.gov (United States)

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

2017-08-09

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

29Si MAS NMR for the zeolite Y - gallium oxide system

International Nuclear Information System (INIS)

Sulikowski, B.; Derewinski, M.; Olejniczak, Z.; Segnowski, S.

1994-01-01

Wide-pore zeolites modified by gallium oxide has been prepared for catalytic use. Its physico-chemical and catalytic properties have been studied. The structure changes of the catalyst have been investigated by means of MAS NMR spectroscopy. Spectra of 29 Si has been described and discussed

HR-MAS NMR allied to chemometric on Hancornia speciosa varieties differentiation

Energy Technology Data Exchange (ETDEWEB)

Flores, Igor S. [Instituto Federal de Goiás (IFG), Luziânia, GO (Brazil); Silva, Andressa K.; Chaves, Lazaro J.; Collevatti, Rosane G.; Lião, Luciano M., E-mail: lucianoliao@ufg.br [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil); Furquim, Leonnardo C. [Faculdade Objetivo, GO (Brazil); Castro, Carlos F.S. [Instituto Federal de Educação, Ciência e Tecnologia Goiano (IFGoiano), GO (Brazil)

2018-05-01

This work describes the potential of chemometric analyses applied to {sup 1}H high-resolution magic angle spinning nuclear magnetic resonance ({sup 1}H HR-MAS NMR) data for the chemotaxonomic investigation of Hancornia speciosa (Apocynaceae) varieties. This plant, popularly known as mangaba, has a complex morphological differentiation and thus chemical analyses can be used for their taxonomic classification. In comparison to traditional techniques, {sup 1}H HR-MAS NMR allied with chemometrics provided a simple and low cost method for chemotaxonomy. Leaves of four varieties of H. speciosa from a common garden experiment was studied and demonstrated that H. speciosa var. speciosa differs from others due to its specific metabolic profile, and var. pubescens was discriminated based on its high phenolic compound content. The distinction between the latter variety and gardineri is important once it allows for the selection of samples with greater commercial value, once they produce the largest and heaviest fruits. (author)

Evidence for radiation induced crosslinking in polytetrafluoroethylene by means of high-resolution solid-state 19F high-speed MAS NMR

International Nuclear Information System (INIS)

Katoh, Etsuko; Sugisawa, Hisashi; Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao; Yamazaki, Toshimasa

1999-01-01

Radiation effects on molecular structure of polytetrafluoroethylene (PTFE) were studied by high-resolution solid-state 19 F high speed magic angle spinning (HS MAS) NMR spectroscopy. Samples used for the NMR studies were prepared by electron beam irradiation of PTFE with a wide range of irradiation doses from 0.5-10 MGy in the molten state at 340 deg. C under oxygen-free atmosphere. While the non-irradiated PTFE displayed only an intense peak of the internal CF 2 , several new signals corresponding to CF 3 , CF 2 and CF groups were observed for the PTFE which was high temperature irradiated at 340 deg. C in oxygen-free atmosphere (hti-PTFE). Intensities of these new signals increased with an increase of irradiation dose. The present solid-state 19 F HS MAS NMR studies provide not only the first experimental evidence regarding the existence of crosslinking structure in hti-PTFE, directly detected as the CF signal, but also the crosslinking density which can be estimated from a proportion of the CF versus total fluorine signal intensities. The higher the irradiation dose, the higher the crosslinking density; hti-PTFE with 10 MGy contains one crosslinking site per approximately 24 CF 2 groups, while the hti-PTFE with 5 MGy contains one crosslinking site per approximately 36 CF 2 groups. Further, G value of crosslinking (G(x)) was estimated from the signal intensities of 19 F HS MAS NMR spectra. The highest G(x)-value, 1.85, was observed for the 2MGy hti-PTFE sample, suggesting that crosslinking of PTFE is formed most efficaciously with 2 MGy irradiation in the molten state at 340 deg. C under oxygen-free atmosphere

Biomolecular solid state NMR with magic-angle spinning at 25K.

Science.gov (United States)

Thurber, Kent R; Tycko, Robert

2008-12-01

A magic-angle spinning (MAS) probe has been constructed which allows the sample to be cooled with helium, while the MAS bearing and drive gases are nitrogen. The sample can be cooled to 25K using roughly 3 L/h of liquid helium, while the 4-mm diameter rotor spins at 6.7 kHz with good stability (+/-5 Hz) for many hours. Proton decoupling fields up to at least 130 kHz can be applied. This helium-cooled MAS probe enables a variety of one-dimensional and two-dimensional NMR experiments on biomolecular solids and other materials at low temperatures, with signal-to-noise proportional to 1/T. We show examples of low-temperature (13)C NMR data for two biomolecular samples, namely the peptide Abeta(14-23) in the form of amyloid fibrils and the protein HP35 in frozen glycerol/water solution. Issues related to temperature calibration, spin-lattice relaxation at low temperatures, paramagnetic doping of frozen solutions, and (13)C MAS NMR linewidths are discussed.

Magnetization and 13C NMR spin-lattice relaxation of nanodiamond powder

Energy Technology Data Exchange (ETDEWEB)

Levin, E.M.; Fang, X.W.; Bud' ko, S.L.; Straszheim, W.E.; McCallum, R.W.; Schmidt-Rohr, K.

2008-02-15

The bulk magnetization at temperatures of 1.8-400 K and in magnetic fields up to 70 kOe, the ambient temperature {sup 13}C NMR spin-lattice relaxation, T{sub 1,c}, and the elemental composition of three nanodiamond powder samples have been studied. The total magnetization of nanodiamond can be explained in terms of contributions from (1) the diamagnetic effect of carbon, (2) the paramagnetic effect of unpaired electrons present in nanodiamond grains, and (3) ferromagnetic-like and (4) superparamagnetic contributions from Fe-containing particles detected in spatially resolved energy-dispersive spectroscopy. Contributions (1) and (2) are intrinsic to nanodiamond, while contributions (3) and (4) arise from impurities naturally present in detonation nanodiamond samples. {sup 13}C NMR T{sub 1,c} relaxation would be unaffected by the presence of the ferromagnetic particles with the bulk magnetization of {approx} 0.01 emu/g at 300 K. Thus, a reduction of T{sub 1,c} by 3 orders of magnitude compared to natural and synthetic microdiamonds confirms the presence of unpaired electrons in the nanodiamond grains. The spin concentration in nanodiamond powder corresponds to {approx}30 unpaired electrons per {approx}4.6 nm diameter nanodiamond grain.

Improved background suppression in ¹H MAS NMR using composite pulses.

Science.gov (United States)

Odedra, Smita; Wimperis, Stephen

2012-08-01

A well known feature of ¹H MAS NMR spectroscopy, particularly of solids where the concentration of ¹H nuclei is low, is the presence in the spectrum of a significant broad "background" signal arising from ¹H nuclei that are outside the MAS rotor and radiofrequency coil, probably located on the surfaces of the static components of the probehead. A popular method of suppressing this unwanted signal is the "depth pulse" method, consisting of a 90° pulse followed by one or two 180° pulses that are phase cycled according to the "Exorcycle" scheme, which removes signal associated with imperfect 180° pulses. Consequently, only spins in the centre of the radiofrequency coil contribute to the ¹H MAS spectrum, while those experiencing a low B₁ field outside the coil are suppressed. Although very effective at removing background signal from the spectrum, one drawback with this approach is that significant loss of the desired signal from the sample also occurs. Here we investigate the ¹H background suppression problem and, in particular, the use of novel antisymmetric passband composite pulses to replace the simple pulses in a depth pulse experiment. We show that it is possible to improve the intensity of the ¹H signals of interest while still maintaining effective background suppression. We expect that these results will be relevant to ¹H MAS NMR studies of, for example, nominally perdeuterated biological samples or nominally anhydrous inorganic materials. Copyright © 2012 Elsevier Inc. All rights reserved.

Complete 1H and 13C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

International Nuclear Information System (INIS)

Johann, Susana; Smania Junior, Artur; Branco, Alexsandro

2007-01-01

A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- ( 1 H NMR, { 1 H} -13 C NMR, and APT -13 C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete 1 H and 13 C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated. (author)

{sup 13}C NMR and EPR spectroscopic evaluation of oil shale mined soil recuperation

Energy Technology Data Exchange (ETDEWEB)

Santos, J.V. dos, E-mail: mangrich@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Mangrich, A.S. [Instituto Nacional de Ciencia e Tecnologia: Energia e Ambiente, Salvador, BA (Brazil); Pereira, B.F. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil); Pillon, C.N. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil). Estacao Experimental Cascata; Novotny, E.H. [EMBRAPA Solos, Rio de Janeiro, RJ (Brazil); Bonagamba, T.J. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica; Abbt-Braun, G.; Frimmel, F.H. [Engler-Bunte-Institut, Universitaet Karlsruhe, TH (Germany)

2013-02-15

In this work, native forest soil (NFS) organic matter (SOM) sample and SOM samples from a neighboring forest soil area of an oil shale mine which is being rehabilitated for thirty years (RFS) were analyzed. X-band electron paramagnetic resonance (EPR) and solid-state {sup 13}C nuclear magnetic resonance (NMR) spectroscopies were used to evaluate the soil reclamation of the Brazilian oil shale mining process. Two-dimensional heterospectral correlation studies of the results obtained from EPRand {sup 13}C NMR were used to obtain information about SOM structures and their interactions with residual paramagnetic metal ion. The signal of the residual metallic oxycation, VO{sup 2+} correlated positively with uronic acid-type hydrophilic organic structures, determined from the {sup 13}C NMR spectra, and correlated negatively with the organic free radical (OFR) signal associated with oxygen atoms (g = 2.0042). The hydrophobic aromatic structures correlate positively with the EPR OFR signal associated with carbon atoms (g = 2.0022). The data from the two spectroscopic magnetic techniques show that the used recuperation process is effective. (author)

A First Laboratory Utilizing NMR for Undergraduate Education: Characterization of Edible Fats and Oils by Quantitative [superscript 13]C NMR

Science.gov (United States)

Fry, Charles G.; Hofstetter, Heike; Bowman, Matthew D.

2017-01-01

Quantitative [superscript 13]C NMR provides a straightforward method of analyzing edible oils in undergraduate chemistry laboratories. [superscript 13]C spectra are relatively easy to understand, and are much simpler to analyze and workup than corresponding [superscript 1]H spectra. Average chain length, degree of saturation, and average…

Hydration properties and phosphorous speciation in native, gelatinized and enzymatically modified potato starch analyzed by solid-state MAS NMR

DEFF Research Database (Denmark)

Larsen, Flemming H.; Kasprzak, Miroslaw Marek; Lærke, Helle Nygaard

2013-01-01

Hydration of granular, gelatinized and molecularly modified states of potato starch in terms of molecular mobility were analyzed by 13C and 31P solid-state MAS NMR. Gelatinization (GEL) tremendously reduced the immobile fraction compared to native (NA) starch granules. This effect was enhanced...... by enzyme-assisted catalytic branching with branching enzyme (BE) or combined BE and β-amylase (BB) catalyzed exo-hydrolysis. Carbons of the glycosidic α-1,6 linkages required high hydration rates before adopting uniform chemical shifts indicating solid-state disorder and poor water accessibility...... regions was only observed in NA starch. Moreover phosphorous was observed in a minor pH-insensitive form and as major phosphate in hydrated GEL and BE starches....

Solid state NMR study of cumbaru flour

International Nuclear Information System (INIS)

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

2001-01-01

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

Solid state 13 C NMR quantitative study of wood tar pitches

International Nuclear Information System (INIS)

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

1999-01-01

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

Occurrence, biological activities and 13C NMR data of amides from Piper (Piperaceae)

International Nuclear Information System (INIS)

Nascimento, Jeferson C. do; Paula, Vanderlucia F. de; David, Jorge M.; David, Juceni P.

2012-01-01

This manuscript describes an update review with up to 285 references concerning the occurrence of amides from a variety of species of the genus Piper (Piperaceae). Besides addressing occurrence, this review also describes the biological activities attributed to extracts and pure compounds, a compiled 13 C NMR data set, the main correlations between structural and NMR spectroscopic data of these compounds, and employment of hyphened techniques such as LC-MS, GC-MS and NMR for analysis of amides from biological samples and crude Piper extracts. (author)

Methodology for the identification of tri-terpenes mixtures components by {sup 13} C NMR; Metodologia para identificao dos componentes de misturas de triterpenos por RMN de {sup 13} C

Energy Technology Data Exchange (ETDEWEB)

Olea, Roberto S.G.

1990-12-31

This work describes a methodology for the identification of tri terpenes complex mixtures by {sup 13} C NMR. The use of {sup 13} C NMR techniques, such as obtention of noise decoupled spectra, DEPT 135 and DEPT 90 sequences, allowed the identification of components of triterpene mixtures with identical functionality through comparison of observed {sup 13} C NMR chemical shifts with {sup 13} C NMR chemical shifts reported in the literature. The method proved to be specially helpful in the identification of triterpenes by analysis of chemical shifts assignable to doubly bonded carbons, since the particular position of such double bonds is characteristic of some triterpene skeletons. Application of this methodology indicated the presence of bauerenol, {alpha}-amyrin and {beta}-amyrin in Acmanthera latifolis Griseb. (Malpighiaceae); of germanicone, lupenone, {alpha}-amyrenone and {beta}-amyrenone in Alibertia macrophylla A. Rich. (Rubiaceae); of {alpha}-amyrin acetate, lupeol acetate and {beta}-amyrin acetate in Vernonia polyanthes Schreb. (Asteraceae); {alpha}-amyrenone, {beta}-amyrenone, boehmerone, friedelin, lupenone, {alpha}-amyrin, {beta}-amyrin and glutinol in Scoparia dulcis L. (Scrophulariaceae). (author). 37 refs., 93 figs.

Methodology for the identification of tri-terpenes mixtures components by {sup 13} C NMR; Metodologia para identificao dos componentes de misturas de triterpenos por RMN de {sup 13} C

Energy Technology Data Exchange (ETDEWEB)

Olea, Roberto S.G.

1991-12-31

This work describes a methodology for the identification of tri terpenes complex mixtures by {sup 13} C NMR. The use of {sup 13} C NMR techniques, such as obtention of noise decoupled spectra, DEPT 135 and DEPT 90 sequences, allowed the identification of components of triterpene mixtures with identical functionality through comparison of observed {sup 13} C NMR chemical shifts with {sup 13} C NMR chemical shifts reported in the literature. The method proved to be specially helpful in the identification of triterpenes by analysis of chemical shifts assignable to doubly bonded carbons, since the particular position of such double bonds is characteristic of some triterpene skeletons. Application of this methodology indicated the presence of bauerenol, {alpha}-amyrin and {beta}-amyrin in Acmanthera latifolis Griseb. (Malpighiaceae); of germanicone, lupenone, {alpha}-amyrenone and {beta}-amyrenone in Alibertia macrophylla A. Rich. (Rubiaceae); of {alpha}-amyrin acetate, lupeol acetate and {beta}-amyrin acetate in Vernonia polyanthes Schreb. (Asteraceae); {alpha}-amyrenone, {beta}-amyrenone, boehmerone, friedelin, lupenone, {alpha}-amyrin, {beta}-amyrin and glutinol in Scoparia dulcis L. (Scrophulariaceae). (author). 37 refs., 93 figs.

(13)C-(15)N correlation via unsymmetrical indirect covariance NMR: application to vinblastine.

Science.gov (United States)

Martin, Gary E; Hilton, Bruce D; Blinov, Kirill A; Williams, Antony J

2007-12-01

Unsymmetrical indirect covariance processing methods allow the derivation of hyphenated 2D NMR data from the component 2D spectra, potentially circumventing the acquisition of the much lower sensitivity hyphenated 2D NMR experimental data. Calculation of HSQC-COSY and HSQC-NOESY spectra from GHSQC, COSY, and NOESY spectra, respectively, has been reported. The use of unsymmetrical indirect covariance processing has also been applied to the combination of (1)H- (13)C GHSQC and (1)H- (15)N long-range correlation data (GHMBC, IMPEACH, or CIGAR-HMBC). The application of unsymmetrical indirect covariance processing to spectra of vinblastine is now reported, specifically the algorithmic extraction of (13)C- (15)N correlations via the unsymmetrical indirect covariance processing of the combination of (1)H- (13)C GHSQC and long-range (1)H- (15)N GHMBC to produce the equivalent of a (13)C- (15)N HSQC-HMBC correlation spectrum. The elimination of artifact responses with aromatic solvent-induced shifts (ASIS) is shown in addition to a method of forecasting potential artifact responses through the indirect covariance processing of the GHSQC spectrum used in the unsymmetrical indirect covariance processing.

Novel NMR tools to study structure and dynamics of biomembranes.

Science.gov (United States)

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

2002-06-01

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

Occurrence, biological activities and 13C NMR data of amides from Piper (Piperaceae

Directory of Open Access Journals (Sweden)

Jeferson C. do Nascimento

2012-01-01

Full Text Available This manuscript describes an update review with up to 285 references concerning the occurrence of amides from a variety of species of the genus Piper (Piperaceae. Besides addressing occurrence, this review also describes the biological activities attributed to extracts and pure compounds, a compiled 13C NMR data set, the main correlations between structural and NMR spectroscopic data of these compounds, and employment of hyphened techniques such as LC-MS, GC-MS and NMR for analysis of amides from biological samples and crude Piper extracts.

The ratio of acetate-to-glucose oxidation in astrocytes from a single 13C NMR spectrum of cerebral cortex.

Science.gov (United States)

Marin-Valencia, Isaac; Hooshyar, M Ali; Pichumani, Kumar; Sherry, A Dean; Malloy, Craig R

2015-01-01

The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate. © 2014 International Society for Neurochemistry.

Direct 13C-detected NMR experiments for mapping and characterization of hydrogen bonds in RNA

International Nuclear Information System (INIS)

Fürtig, Boris; Schnieders, Robbin; Richter, Christian; Zetzsche, Heidi; Keyhani, Sara; Helmling, Christina; Kovacs, Helena; Schwalbe, Harald

2016-01-01

In RNA secondary structure determination, it is essential to determine whether a nucleotide is base-paired and not. Base-pairing of nucleotides is mediated by hydrogen bonds. The NMR characterization of hydrogen bonds relies on experiments correlating the NMR resonances of exchangeable protons and can be best performed for structured parts of the RNA, where labile hydrogen atoms are protected from solvent exchange. Functionally important regions in RNA, however, frequently reveal increased dynamic disorder which often leads to NMR signals of exchangeable protons that are broadened beyond 1 H detection. Here, we develop 13 C direct detected experiments to observe all nucleotides in RNA irrespective of whether they are involved in hydrogen bonds or not. Exploiting the self-decoupling of scalar couplings due to the exchange process, the hydrogen bonding behavior of the hydrogen bond donor of each individual nucleotide can be determined. Furthermore, the adaption of HNN-COSY experiments for 13 C direct detection allows correlations of donor–acceptor pairs and the localization of hydrogen-bond acceptor nucleotides. The proposed 13 C direct detected experiments therefore provide information about molecular sites not amenable by conventional proton-detected methods. Such information makes the RNA secondary structure determination by NMR more accurate and helps to validate secondary structure predictions based on bioinformatics.

Study of lignin standard-substances type biphenyl by {sup 13} C NMR; Estudo de substancias-modelo de lignina do tipo bifenila, por RMN de {sup 13} C

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Marcia Alves; Drumond, Mariza Guimaraes; Veloso, Dorila Pilo [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica

1995-12-31

Lignins structural study by NMR has utilized standard-substances spectral comparative analysis. This work has present relaxation time studies for lignin standard-substance, and {sup 13} C NMR chemical shift values were also shown and compared for several compounds. NMR spectra were commented besides experimental data analysis 2 figs., 4 tabs.

Aspects of reaction of N-oxide radical with ethers in 13C NMR spectrum

International Nuclear Information System (INIS)

Kolodziejski, W.

1980-01-01

The stable radical N-oxide 2,2,6,6-tetramethylpiperidine was dissolved in ethers. The 13 C NMR spectra were recorded in the temperature 313K at the frequency 22,625 MHz on the spectrometers with Fourier transformation. The dissolution of the radical in ether caused the contact shifts in NMR spectra. The shifts were measured. (A.S.)

Acetylenes bearing Aromatic Terminal Groups. : II 13C-NMR Spectra of Monosubstituted Diphenylacetylenes

OpenAIRE

野本, 健雄; Nomoto, Takeo

1986-01-01

Six monosubstituted diphenylacetylenes, p-X-C6H4-C≡C-C6H5 1 (Ⅹ=NMe2, NH2, OMe, Cl, and NO2), were synthesized, and 13C-NMR spectra of their acetylenic carbons were measured. Hammett plots of the chemical shifts of the acetylenic α-13C and β-13C (against substituent constants σ) respectively showed a linear relationship, eXCept for β-13C on NMe2 and NH2 groups. The effects of substituents on 13C-Chemical shifts of diphenylacetylenes and effeciency of the C≡C bonds in transmitting the substitue...

Comparison of IRMS and NMR spectrometry for the determination of intramolecular 13C isotope composition: application to ethanol.

Science.gov (United States)

Gilbert, Alexis; Hattori, Ryota; Silvestre, Virginie; Wasano, Nariaki; Akoka, Serge; Hirano, Satoshi; Yamada, Keita; Yoshida, Naohiro; Remaud, Gérald S

2012-09-15

Isotopic (13)C NMR is a relatively recent technique which allows the determination of intramolecular (13)C isotope composition at natural abundance. It has been used in various scientific fields such as authentication, counterfeiting or plant metabolism. Although its precision has already been evaluated, the determination of its trueness remains still challenging. To deal with that issue, a comparison with another normalized technique must be achieved. In this work, we compare the intramolecular (13)C isotope distribution of ethanol from different origins obtained using both Isotope Ratio Mass Spectrometry (IRMS) and Nuclear Magnetic Resonance (NMR) spectrometry techniques. The IRMS approach consists of the oxidation of ethanol to acetic acid followed by the degradation of the latter for the analysis of each fragments formed. We show here that the oxidation of ethanol to acetic acid does not bring any significant error on the determination of the site-specific δ(13)C (δ(13)C(i)) of ethanol using the IRMS approach. The difference between the data obtained for 16 samples from different origins using IRMS and NMR approaches is not statistically significant and remains below 0.3‰. These results are encouraging for the future studies using isotopic NMR, especially in combination with the IRMS approach. Copyright © 2012. Published by Elsevier B.V.

CP/MAS ¹³C NMR study of pulp hornification using nanocrystalline cellulose as a model system.

Science.gov (United States)

Idström, Alexander; Brelid, Harald; Nydén, Magnus; Nordstierna, Lars

2013-01-30

The hornification process of paper pulp was investigated using solid-state (13)C NMR spectroscopy. Nanocrystalline cellulose was used to serve as a model system of the crystalline parts of the fibrils in pulp fibers. Characterization of the nanocrystalline cellulose dimensions was carried out using scanning electron microscopy. The samples were treated by drying and wetting cycles prior to NMR analysis where the hornification phenomenon was recorded by spectral changes of the cellulose C-4 carbon signals. An increase of the crystalline signal and a decrease of the signals corresponding to the accessible amorphous domains were found for both paper pulp and nanocrystalline cellulose. These spectral changes grew stronger with repeating drying and wetting cycles. The results show that cellulose co-crystallization contribute to hornification. Another conclusion is that the surfaces of higher hydrophobicity in cellulose fibrils have an increased preference for aggregation. Copyright © 2012 Elsevier Ltd. All rights reserved.

(1 H, 13 C and 31 P) NMR of phosphonic acid derivatives

International Nuclear Information System (INIS)

Campos, Valdevino; Costa, Valentim E. Uberti

1991-01-01

In the last years the development of phosphates analogues in the medical and agricultural pesticides has being very expressive. 1 H, 13 C and mainly 31 P NMR are used for stereochemical and conformational analysis, and reactivity studies on the compounds resulting from those chemical processes

Configurations and conformations in acyclic, unsaturated hydrocarbons. A 13C NMR study

NARCIS (Netherlands)

Haan, de J.W.; Ven, van de L.J.M.

1973-01-01

13C NMR (CMR) spectra of a number of di- and trisubstituted ethylenes have been measured. Very consistent values are found for the differential shieldings of allylic carbons in a number of linear, (Z)- and (E)-disubstituted ethylenes. The discrepancies between the several structural elements are

Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR.

Science.gov (United States)

Hubert, Jane; Nuzillard, Jean-Marc; Purson, Sylvain; Hamzaoui, Mahmoud; Borie, Nicolas; Reynaud, Romain; Renault, Jean-Hugues

2014-03-18

Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside.

Occurrence, biological activities and {sup 13}C NMR data of amides from Piper (Piperaceae)

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Jeferson C. do; Paula, Vanderlucia F. de [Universidade Estadual do Sudoeste da Bahia, Jequie, BA (Brazil). Dept. de Quimica e Exatas; David, Jorge M. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; David, Juceni P., E-mail: jmdavid@ufba.br [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Fac. de Farmacia

2012-07-01

This manuscript describes an update review with up to 285 references concerning the occurrence of amides from a variety of species of the genus Piper (Piperaceae). Besides addressing occurrence, this review also describes the biological activities attributed to extracts and pure compounds, a compiled {sup 13}C NMR data set, the main correlations between structural and NMR spectroscopic data of these compounds, and employment of hyphened techniques such as LC-MS, GC-MS and NMR for analysis of amides from biological samples and crude Piper extracts. (author)

Spectrally edited 2D 13Csbnd 13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials

Science.gov (United States)

Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

2013-09-01

Two robust combinations of spectral editing techniques with 2D 13Csbnd 13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, Csbnd H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and Cdbnd O carbons

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

Science.gov (United States)

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

2017-07-01

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

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.

Structural properties of carbon nanotubes derived from 13C NMR

KAUST Repository

Abou-Hamad, E.

2011-10-10

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

Application of unsymmetrical indirect covariance NMR methods to the computation of the (13)C (15)N HSQC-IMPEACH and (13)C (15)N HMBC-IMPEACH correlation spectra.

Science.gov (United States)

Martin, Gary E; Hilton, Bruce D; Irish, Patrick A; Blinov, Kirill A; Williams, Antony J

2007-10-01

Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. (c) 2007 John Wiley & Sons, Ltd.

Probing Metal Carbonation Reactions of CO2 in a Model System Containing Forsterite and H2O Using Si-29, C-13 Magic Angle Sample Spinning NMR Spectroscopy

Science.gov (United States)

Hu, J.; Kwak, J.; Hoyt, D. W.; Sears, J. A.; Rosso, K. M.; Felmy, A. R.

2009-12-01

Ex situ solid state NMR have been used for the first time to study fundamental mineral carbonation processes and reaction extent relevant to geologic carbon sequestration using a model silicate mineral forsterite (Mg2SiO4)+scCO2 with and without H2O. Run conditions were 80C and 96 bar. Si-29 NMR clearly shows that in the absence of CO2, the role of H2O is to hydrolyze surface Mg-O-Si bonds to produce Mg2+, and mono- and oligomeric hydroxylated silica species. The surface hydrolysis products contain only Q0 (Si(OH)4) and Q1 (Si(OH)3OSi) species. An equilibrium between Q0, Q1 and Mg2+ with a saturated concentration equivalent to less than 3.2% of the Mg2SiO4 conversion is obtained at a reaction time of up to 7 days. Using scCO2 without H2O, no reaction is observed within 7 days. Using both scCO2 and H2O, the surface reaction products for silica are mainly Q3 (SiOH(OSi)3) species accompanied by a lesser amount of Q2 (Si(OH)2(OSi)2) and Q4 (Si(OSi)4). However, no Q0 and Q1 were detected, indicating the carbonic acid formation/deprotonation and magnesite (MgCO3) precipitation reactions are faster than the forsterite hydrolysis process. Thus it can be concluded that the Mg2SiO4 hydrolysis process is the rate limiting step of the overall mineral carbonation process. Si-29 NMR combined with XRD, TEM, SAED and EDX further reveal that the reaction is a surface reaction with the Mg2SiO4 crystallite in the core and with condensed Q2-Q4 species forming amorphous surface layers. C-13 MAS NMR identified a possible reaction intermediates as (MgCO3)4*Mg(OH)2*5H2O. However, at long reaction times only crystallite magnesite MgCO3 products are observed. This research is part of a broader effort at PNNL to develop experimental tools and fundamental insights into chemical transformations affecting subsurface CO2 reactive transport. Si-29 (left) and C-13 (right) MAS NMR spectra of Mg2SiO4 under various reaction conditions. Si-29 NMR reveals that in scCO2 without H2O, no reaction is

Molecular motion of micellar solutes: a 13C NMR relaxation study

International Nuclear Information System (INIS)

Stark, R.E.; Kasakevich, M.L.; Granger, J.W.

1982-01-01

A series of simple NMR relaxation experiments have been performed on nitrobenzene and aniline dissolved in the ionic detergents sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB). Using 13 C relaxation rates at various molecular sites, and comparing data obtained in organic media with those for micellar solutions, the viscosity at the solubilization site was estimated and a detailed picture of motional restrictions imposed by the micellar enviroment was derived. Viscosities of 8 to 17 cp indicate a rather fluid environment for solubilized nitrobenzene; both additives exhibit altered motional preferences in CTAB solutions only. As an aid in interpretation of the NMR data, quasi-elastic light scattering and other physical techniques have been used to evaluate the influence of organic solutes on micellar size and shape. The NMR methods are examined critically in terms of their general usefulness for studies of solubilization in detergent micelles. 48 references

Direct {sup 13}C-detected NMR experiments for mapping and characterization of hydrogen bonds in RNA

Energy Technology Data Exchange (ETDEWEB)

Fürtig, Boris, E-mail: fuertig@nmr.uni-frankfurt.de; Schnieders, Robbin; Richter, Christian; Zetzsche, Heidi; Keyhani, Sara; Helmling, Christina [Johann Wolfgang Goethe Universität Frankfurt, Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology (Germany); Kovacs, Helena [Bruker BioSpin (Switzerland); Schwalbe, Harald, E-mail: schwalbe@nmr.uni-frankfurt.de [Johann Wolfgang Goethe Universität Frankfurt, Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology (Germany)

2016-03-15

In RNA secondary structure determination, it is essential to determine whether a nucleotide is base-paired and not. Base-pairing of nucleotides is mediated by hydrogen bonds. The NMR characterization of hydrogen bonds relies on experiments correlating the NMR resonances of exchangeable protons and can be best performed for structured parts of the RNA, where labile hydrogen atoms are protected from solvent exchange. Functionally important regions in RNA, however, frequently reveal increased dynamic disorder which often leads to NMR signals of exchangeable protons that are broadened beyond {sup 1}H detection. Here, we develop {sup 13}C direct detected experiments to observe all nucleotides in RNA irrespective of whether they are involved in hydrogen bonds or not. Exploiting the self-decoupling of scalar couplings due to the exchange process, the hydrogen bonding behavior of the hydrogen bond donor of each individual nucleotide can be determined. Furthermore, the adaption of HNN-COSY experiments for {sup 13}C direct detection allows correlations of donor–acceptor pairs and the localization of hydrogen-bond acceptor nucleotides. The proposed {sup 13}C direct detected experiments therefore provide information about molecular sites not amenable by conventional proton-detected methods. Such information makes the RNA secondary structure determination by NMR more accurate and helps to validate secondary structure predictions based on bioinformatics.

NMR study of the 1-13C glucose colon bacterial metabolism

International Nuclear Information System (INIS)

Briet, F.; Flourie, B.; Pochart, P.; Rambaud, J.C.; Desjeux, J.F.; Dallery, L.; Grivet, J.P.

1994-01-01

The aim of the study is to examine in-vitro and by nuclear magnetic resonance the biological pathways for the fermentation of the 1- 13 C labelled glucose (99 atoms percent) by human colon bacteria. The preparation of the bacterial suspension and the glucose degradation kinetics are presented; the NMR analysis sensitivity and quantification features are discussed and results are presented. 2 figs., 1 ref

A 13C{31P} REDOR NMR Investigation of the Role of Glutamic Acid Residues in Statherin-Hydroxyapatite Recognition

Science.gov (United States)

Ndao, Moise; Ash, Jason T.; Breen, Nicholas F.; Goobes, Gil; Stayton, Patrick S.; Drobny, Gary P.

2011-01-01

The side chain carboxyl groups of acidic proteins found in the extra-cellular matrix (ECM) of mineralized tissues play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), the principal mineral component of bone and teeth. Among the acidic proteins found in the saliva is statherin, a 43-residue tyrosine-rich peptide that is a potent lubricant in the salivary pellicle and an inhibitor of both HAP crystal nucleation and growth. Three acidic amino acids – D1, E4, and E5 – are located in the N-terminal 15 amino acid segment, with a fourth amino acid, E26, located outside the N-terminus. We have utilized 13C{31P} REDOR NMR to analyze the role played by acidic amino acids in the binding mechanism of statherin to the HAP surface by measuring the distance between the δ-carboxyl 13C spins of the three glutamic acid side chains of statherin (residues E4, E5, E26) and 31P spins of the phosphate groups at the HAP surface. 13C{31P} REDOR studies of glutamic-5-13C acid incorporated at positions E4 and E26 indicate a 13C–31P distance of more than 6.5 Å between the side chain carboxyl 13C spin of E4 and the closest 31P in the HAP surface. In contrast, the carboxyl 13C spin at E5 has a much shorter 13C–31P internuclear distance of 4.25±0.09 Å, indicating that the carboxyl group of this side chain interacts directly with the surface. 13C T1ρ and slow-spinning MAS studies indicate that the motions of the side chains of E4 and E5 are more restricted than that of E26. Together, these results provide further insight into the molecular interactions of statherin with HAP surfaces. PMID:19678690

Quantitative analysis of deuterium using the isotopic effect on quaternary {sup 13}C NMR chemical shifts

Energy Technology Data Exchange (ETDEWEB)

Darwish, Tamim A., E-mail: tamim.darwish@ansto.gov.au [National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 21, Kirrawee DC, NSW 2232 (Australia); Yepuri, Nageshwar Rao; Holden, Peter J. [National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 21, Kirrawee DC, NSW 2232 (Australia); James, Michael [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia)

2016-07-13

Quantitative analysis of specifically deuterated compounds can be achieved by a number of conventional methods, such as mass spectroscopy, or by quantifying the residual {sup 1}H NMR signals compared to signals from internal standards. However, site specific quantification using these methods becomes challenging when dealing with non-specifically or randomly deuterated compounds that are produced by metal catalyzed hydrothermal reactions in D{sub 2}O, one of the most convenient deuteration methods. In this study, deuterium-induced NMR isotope shifts of quaternary {sup 13}C resonances neighboring deuterated sites have been utilized to quantify the degree of isotope labeling of molecular sites in non-specifically deuterated molecules. By probing {sup 13}C NMR signals while decoupling both proton and deuterium nuclei, it is possible to resolve {sup 13}C resonances of the different isotopologues based on the isotopic shifts and the degree of deuteration of the carbon atoms. We demonstrate that in different isotopologues, the same quaternary carbon, neighboring partially deuterated carbon atoms, are affected to an equal extent by relaxation. Decoupling both nuclei ({sup 1}H, {sup 2}H) resolves closely separated quaternary {sup 13}C signals of the different isotopologues, and allows their accurate integration and quantification under short relaxation delays (D1 = 1 s) and hence fast accumulative spectral acquisition. We have performed a number of approaches to quantify the deuterium content at different specific sites to demonstrate a convenient and generic analysis method for use in randomly deuterated molecules, or in cases of specifically deuterated molecules where back-exchange processes may take place during work up. - Graphical abstract: The relative intensities of quaternary {sup 13}C {"1H,"2H} resonances are equal despite the different relaxation delays, allowing the relative abundance of the different deuterated isotopologues to be calculated using NMR fast

One-Pot Synthesis, X-Ray Diffraction and MAS NMR Spectroscopic Study of Gallosilicate Nitrate Cancrinite Na8[GaSiO4]6(NO34(H2O6

Directory of Open Access Journals (Sweden)

Ashok V. Borhade

2010-01-01

Full Text Available One-pot synthetic gallosilicate nitrate cancrinite (CAN framework topology have been synthesized under hydrothermal conditions at 100 °C. The synthesized product was characterized by, X-ray powder diffraction, IR, Raman and 29Si, 23Na MAS NMR spectroscopy, SEM and thermogravimetry. The crystal structure refinement of pure nitrate cancrinite has been carried out from X-ray data using Rietveld refinement method. Gallosilicate cancrinite Na8[GaSiO4]6(NO34(H2O6 crystalline hexagonal with space group P63 and a = 12.77981 Å (2, c = 5.20217 Å (1, (Rwp = 0.0696 Rp = 0.0527. The results by MAS NMR spectroscopy confirmed the alternating Si, Ga ordering of the gallosilicate framework for a Si/Ga ratio of 1.0. A distribution of the quadrupolar interaction of the sodium cations caused by the enclatherated water molecules and motional effects can be suggested from the 23Na MAS NMR. Thermogravimetric investigation shows the extent of nitrate entrapment, stability within the cancrinite cage and decomposition properties. SEM clearly shows the hexagonal needle shaped crystals of nitrate cancrinite.

1H, 15N and 13C NMR Assignments of Mouse Methionine Sulfoxide Reductase B2

Science.gov (United States)

Breivik, Åshild S.; Aachmann, Finn L.; Sal, Lena S.; Kim, Hwa-Young; Del Conte, Rebecca; Gladyshev, Vadim N.; Dikiy, Alexander

2011-01-01

A recombinant mouse methionine-r-sulfoxide reductase 2 (MsrB2ΔS) isotopically labeled with 15N and 15N/13C was generated. We report here the 1H, 15N and 13C NMR assignments of the reduced form of this protein. PMID:19636904

Complete {sup 1}H and {sup 13}C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

Energy Technology Data Exchange (ETDEWEB)

Johann, Susana; Smania Junior, Artur [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Microbiologia e Parasitologia. Lab. de Antibioticos; Pizzolatti, Moacir G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica; Schripsema, Jan; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Setor de Quimica de Produtos Naturais. Lab. de Quimica e Funcao de Proteinas e Peptideos (LQFPP); Branco, Alexsandro [Universidade Estadual de Feira de Santana, BA (Brazil). Dept. de Saude. Lab. de Fitoquimica]. E-mail: branco@uefs.br

2007-06-15

A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- ({sup 1}H NMR, {l_brace}{sup 1}H{r_brace} {sup -13}C NMR, and APT{sup -13}C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete {sup 1}H and {sup 13}C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated. (author)

Quantitative evaluation of the biosynthetic pathways leading to δ-aminolevulinic acid from the Shemin precursor glycine via the C5 pathway in Arthrobacter hyalinus by analysis of 13C-labeled coproporphyrinogen III biosynthesized from [2-13C]glycine, [1-13C]acetate, and [2-13C]acetate using 13C NMR spectroscopy

International Nuclear Information System (INIS)

Katsumi Iida

2013-01-01

The biosynthetic pathways leading to δ-aminolevulinic acid (ALA) from the Shemin precursor glycine via the C5 pathway in Arthrobacter hyalinus were quantitatively evaluated by means of feeding experiments with [2- 13 C]glycine, sodium [1- 13 C]acetate, and sodium [2- 13 C]acetate, followed by analysis of the labeling patterns of coproporphyrinogen III (Copro'gen III) (biosynthesized from ALA) using 13 C NMR spectroscopy. Two biosynthetic pathways leading to ALA from glycine via the C5 pathway were identified: i.e., transformation of glycine to l-serine catalyzed by glycine hydroxymethyltransferase, and glycine synthase-catalyzed catabolism of glycine to N 5 , N 10 -methylene-tetrahydrofolic acid (THF), which reacts with another molecule of glycine to afford l-serine. l-Serine is transformed to acetyl-CoA via pyruvic acid. Acetyl-CoA enters the tricarboxylic acid cycle, affording 2-oxoglutaric acid, which in turn is transformed to l-glutamic acid. The l-glutamic acid enters the C5 pathway, affording ALA in A. hyalinus. A 13 C NMR spectroscopic comparison of the labeling patterns of Copro'gen III obtained after feeding of [2- 13 C]glycine, sodium [1- 13 C]acetate, and sodium [2- 13 C]acetate showed that [2- 13 C]glycine transformation and [2- 13 C]glycine catabolism in A. hyalinus proceed in the ratio of 52 and 48 %. The reaction of [2- 13 C]glycine and N 5 , N 10 -methylene-THF, that of glycine and N 5 , N 10 -[methylene- 13 C]methylene-THF generated from the [2- 13 C]glycine catabolism, and that of [2- 13 C]glycine and N 5 , N 10 -[methylene- 13 C]methylene-THF transformed the fed [2- 13 C]glycine to [1- 13 C]acetyl-CoA, [2- 13 C]acetyl-CoA, and [1,2- 13 C 2 ]acetyl-CoA in the ratios of 42, 37, and 21 %, respectively. These labeled acetyl-CoAs were then incorporated into ALA. Our results provide a quantitative picture of the pathways of biosynthetic transformation to ALA from glycine in A. hyalinus. (author)

Computer-aided structure analysis. Structure identification by infrared and /sup 13/C NMR measurements

Energy Technology Data Exchange (ETDEWEB)

Szalontai, G; Simon, Z; Csapo, Z; Farkas, M; Pfeifer, Gy [Nehezvegyipari Kutato Intezet, Veszprem (Hungary)

1980-01-01

The results obtained from the computer-aided interpretation of /sup 13/C NMR and IR spectra using the artificial intelligence approach are presented. In its present state the output of the system is a list of functional groups which are resonable candidates for the final structural isomers. The input requires empirical formula, /sup 13/C NMR data (off resonance data also) and IR spectral data. The confirmation of the presence of a functional group is based on comparison of the experimental data with the spectral properties of functional groups stored in a property matrix. If the molecular weight of the compounds studied is less or equal 500, the output contains usually 1.5-2.5 times more groups than really present, in most cases without the loss of the real ones.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-04-01

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

Robust refocusing of 13C magnetization in multidimensional NMR experiments by adiabatic fast passage pulses

International Nuclear Information System (INIS)

Zweckstetter, Markus; Holak, Tad A.

1999-01-01

We show that adiabatic fast passage (AFP) pulses are robust refocusing elements of transverse 13 C magnetization in multidimensional NMR experiments. A pair of identical AFP pulses can refocus selected parts or a complete 13 C chemical shift range in 13 C spectra. In the constant time 13 C- 1 H HSQC, replacement of attenuated rectangular pulses by selective AFP pulses results in a sensitivity enhancement of up to a factor of 1.8. In the 3D CBCA(CO)NH the signal-to-noise ratio is increased by a factor of up to 1.6

13C CPMAS NMR Studies of Anthocyanidins and their Glucosides

International Nuclear Information System (INIS)

Wolniak, M.; Wawer, I.

2005-01-01

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

13C NMR and stereochestry of 1-β-phenylethylcyclohexanol derivatives obtained by synthesis

International Nuclear Information System (INIS)

Antunes, O.A.C.; Braz Filho, R.

1986-01-01

1-β-Phenylethylcyclohexanol derivatives substituted in position 2 have been synthesized and analysed by 13 C-NMR spectroscopy. Their stereochemistry have been considered as cis (hydroxyl in C-1 and substituent in C-2) which is in agreement with the pertinent literature. Derivatives obtained were 2-β-phenylethyl-2-allycyclohexanol, 1-β-phenylethyl-2-methylcyclohexanol, 7a-β-phenylethylperhy-drobenzo (b) furan, and 1-β-phenylethyl-2-β-hydroxyethylcyclohexanol. (author) [pt

Authentication of the origin of vanillin using quantitative natural abundance 13C NMR.

Science.gov (United States)

Tenailleau, Eve J; Lancelin, Pierre; Robins, Richard J; Akoka, Serge

2004-12-29

The use of 13C isotopic distribution as an efficient means to determine the origin of vanillin has been substantiated. Using quantitative 13C NMR, the 13C/12C ratios at all eight carbon positions can be exploited. On a set of 21 samples of vanillin from five different origins, complete discrimination can be achieved. It is shown that, for many purposes, a rapid analysis in which only five sites are used is sufficient. However, improved discrimination using all eight sites is preferable to differentiate between different methods of production from natural ferulic acid or between natural and lignin-derived vanillin on the basis of the 13C/12C ratios characteristic of different origins. The C1 and C8 positions are demonstrated to be the most significant sites for discrimination using principle component analysis. However, aromatic carbon positions make an essential contribution, notably in differentiating between natural and lignin-derived vanillin.

HR-MAS NMR for rapid identification of illicit substances in tablets and Blotter papers seized by Police Department

International Nuclear Information System (INIS)

Souza, Luciano F.; Vieira, Tarcísio S.; Lião, Luciano M.; Alcantara, Glaucia B.

2016-01-01

Illicit substances found in blotter papers and tablets seized by police are traditionally identified and characterized from extracts of these materials. However, the procedures involved in extraction stages can result in artifacts and even contamination of the samples to be analyzed. On the other hand, high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) is a technique that requires no pretreatment steps, enabling direct analysis of the material, including the analysis of new illegal synthetic psychoactive substances. This study presents and discusses applications of the HR-MAS NMR in the analysis of tablets and blotter papers seized. Additional analysis in solution of the extracts of these materials was performed to compare the obtained spectral resolution signals. The results demonstrated that the HR-MAS NMR allowed the rapid identification of 3,4-methylenedioxy-N-methylcathinone (methylone), 4-methylmethcathinone (mephedrone), 2,5-dimethoxy-4-bromoamphetamine (DOB) and 2-(4-bromo-2,5-dimethoxyphenyl)-N-[(2- methoxyphenyl)methyl]ethanamine (25B-NBOMe) in samples of tablets and blotter papers seized in Goiás State, Brazil. (author)

HR-MAS NMR for rapid identification of illicit substances in tablets and Blotter papers seized by Police Department

Energy Technology Data Exchange (ETDEWEB)

Souza, Luciano F.; Vieira, Tarcísio S.; Lião, Luciano M., E-mail: lucianoliao@ufg.br [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil). Instituto de Química; Alcantara, Glaucia B. [Universidade Federal de Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Instituto de Química

2016-07-01

Illicit substances found in blotter papers and tablets seized by police are traditionally identified and characterized from extracts of these materials. However, the procedures involved in extraction stages can result in artifacts and even contamination of the samples to be analyzed. On the other hand, high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) is a technique that requires no pretreatment steps, enabling direct analysis of the material, including the analysis of new illegal synthetic psychoactive substances. This study presents and discusses applications of the HR-MAS NMR in the analysis of tablets and blotter papers seized. Additional analysis in solution of the extracts of these materials was performed to compare the obtained spectral resolution signals. The results demonstrated that the HR-MAS NMR allowed the rapid identification of 3,4-methylenedioxy-N-methylcathinone (methylone), 4-methylmethcathinone (mephedrone), 2,5-dimethoxy-4-bromoamphetamine (DOB) and 2-(4-bromo-2,5-dimethoxyphenyl)-N-[(2- methoxyphenyl)methyl]ethanamine (25B-NBOMe) in samples of tablets and blotter papers seized in Goiás State, Brazil. (author)

Variable temperature 127I MAS NMR of β-AgI

International Nuclear Information System (INIS)

Wagner, G.W.

1991-01-01

Variable temperature 127 I MAS NMR of β-AgI powder, measured from 123 to 413 K is sensitive to Ag + diffusion through the iodine lattice. In low temperature spectra, the iodine ions appear to be in nearly static environments in agreement with the low temperature crystal structure. However, at higher temperatures, substantial broadening of the central transition linewidth is consistent with the presence of two types of Ag + diffusion with activation energies of 0.17 and 0.0080 eV. (author). 15 refs.; 5 figs.; 1 tab

High-resolution proton and carbon-13 NMR of membranes: why sonicate?

International Nuclear Information System (INIS)

Oldfield, E.; Bowers, J.L.; Forbes, J.

1987-01-01

The authors have obtained high-field (11.7-T) proton and carbon-13 Fourier transform (FT) nuclear magnetic resonance (NMR) spectra of egg lecithin and egg lecithin-chloresterol (1:1) multibilayers, using magic-angle sample spinning (MASS) techniques, and sonicated egg lecithin and egg lecithin-cholesterol (1:1) vesicles, using conventional FT NMR methods. Resolution of the proton and carbon-13 MASS NMR spectra of the pure egg lecithin samples is essentially identical with that of sonicated samples, but spectra of the unsonicated lipid, using MASS, can be obtained very much faster than with the more dilute, sonicated systems. With the 1:1 lecithin-cholesterol system, proton MASS NMR spectra are virtually identical with conventional FT spectra of sonicated samples, while the 13 C NMR, the authors demonstrate that most 13 C nuclei in the cholesterol moiety can be monitored, even though these same nuclei are essentially invisible, i.e., are severely broadened, in the corresponding sonicated systems. In addition, 13 C MASS NMR spectra can again be recorded much faster than with sonicated samples, due to concentration effects. Taken together, these results strongly suggest there will seldom be need in the future to resort to ultransonic disruption of lipid bilayer membranes in order to obtain high-resolution proton or carbon-13 NMR spectra

Use of 13NMR to delineate the mode of association or binding of 13C-labeled pollutants with humic materials

International Nuclear Information System (INIS)

Bortiatynski, J.M.; Minard, R.D.; Hatcher, P.G.

1993-01-01

13 C NMR has recently been shown to be a powerful technique for the examination of the covalent binding of pollutants to humic materials when the latter are enriched with 13 C. Enhanced signals are observed for the carbons that are highly enriched with 13 C while the remaining signals due to naturally abundant 13 C form unlabeled pollutant carbons or humic substances are at the baseline noise level. If covalent bonding and/or non covalent associations take place at or near the site of the 13 C label(s), the nature of the bonding or association can be discerned and the adsorption coefficients can be calculated. In this paper, the authors present the results of such binding studies which demonstrate the great potential of this technique

Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

Energy Technology Data Exchange (ETDEWEB)

Thurber, Kent R., E-mail: thurberk@niddk.nih.gov; Tycko, Robert [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)

2014-05-14

We report solid state {sup 13}C and {sup 1}H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, {sup 1}H and cross-polarized {sup 13}C NMR signals from {sup 15}N,{sup 13}C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T{sub 1e} is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

International Nuclear Information System (INIS)

Thurber, Kent R.; Tycko, Robert

2014-01-01

We report solid state 13 C and 1 H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1 H and cross-polarized 13 C NMR signals from 15 N, 13 C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T 1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations

Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves.

Science.gov (United States)

Thurber, Kent R; Tycko, Robert

2014-05-14

We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

Effects of insulin on perfused liver from streptozotocin-diabetic and untreated rats: 13C NMR assay of pyruvate kinase flux

International Nuclear Information System (INIS)

Cohen, S.M.

1987-01-01

The effects of insulin in vitro on perfused liver from streptozotocin-diabetic rats and their untreated littermates during gluconeogenesis from either [3- 13 C]alanine + ethanol or [2- 13 C]pyruvate + NH 4 Cl + ethanol were studied by 13 C NMR. A 13 C NMR determination of the rate of pyruvate kinase flux under steady-state conditions of active gluconeogenesis was developed; this assay includes a check on the reuse of recycled pyruvate. The preparations studied provided gradations of pyruvate kinase flux within the confines of the assay's requirement of active gluconeogenesis. By this determination, the rate of pyruvate kinase flux was 0.74 +/- 0.04 of the gluconeogenic rate in liver from 24-h-fasted controls; in liver from 12-h fasted controls, relative pyruvate kinase flux increased to 1.0 +/- 0.2. In diabetic liver, this flux was undetectable by the authors NMR method. Insulin's hepatic influence in vitro was greatest in the streptozotocin model of type 1 diabetes: upon treatment of diabetic liver with 7 nM insulin in vitro, a partial reversal of many of the differences noted between diabetic and control liver was demonstrated by 13 C NMR. A major effect of insulin in vitro upon diabetic liver was the induction of a large increase in the rate of pyruvate kinase flux, bringing relative and absolute fluxes up to the levels measured in 24-h-fasted controls. By way of comparison, the effects of ischemia on diabetic liver were studied by 13 C NMR to test whether changes in allosteric effectors under these conditions could also increase pyruvate kinase flux. A large increase in this activity was demonstrated in ischemic diabetic liver

Protolytic properties of polyamine wasp toxin analogues studied by 13C NMR spectroscopy

DEFF Research Database (Denmark)

Strømgaard, Kristian; Piazzi, Lorna; Olsen, Christian A

2006-01-01

Acid-base properties of the natural polyamine wasp toxin PhTX-433 (1) and seven synthetic analogues [PhTX-343 (2), PhTX-334 (3), PhTX-443 (4), PhTX-434 (5), PhTX-344 (6), PhTX-444 (7), and PhTX-333 (8)], each having four protolytic sites, were characterized by 13C NMR spectroscopy. Nonlinear......, multiparameter, simultaneous fit of all chemical shift data obtained from the NMR titration curves yielded macroscopic pKa values as well as intrinsic chemical shift data of all differently protonated macrospecies. Analyses of the chemical shift data demonstrated strong interactions between all four sites...

Microstructure study of ethylene, propylene and 1-decene terpolymers by 13C-NMR

International Nuclear Information System (INIS)

Ferreira, Marcio; Escher, Fernanda Nunes; Galland, Griselda Barrera

2001-01-01

Terpolymers of ethylene-propylene-1-decene with different composition of monomers were obtained using the metallocenes catalyst rac-EtInd 2 ZrCl 2 . The complete 13 C-NMR characterization of these terpolymers was done qualitatively and quantitatively. Chemical shifts, carbon assignments and corresponding integrals for each triad sequence are presented. (author)

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Computational characterization of 13C NMR lineshapes of carbon dioxide in structure 1 clathrate hydrates

Energy Technology Data Exchange (ETDEWEB)

Dornan, P.; Woo, T.K. [Ottawa Univ., ON (Canada). Dept. of Chemistry

2008-07-01

Nonspherical large cages in structure one clathrates impose non-uniform motion of nonspherical guest molecules and anisotropic lineshapes in nuclear magnetic resonance (NMR) spectra of the guest. This paper presented a general method for calculating the chemical shift lineshape anisotropy of guest molecules in clathrate hydrate compounds from molecular dynamics simulations for the case of weak host, guest dipolar coupling. In order to calculate the cage chemical shielding tensors and the NMR lineshape produced by each guest molecule, the study involved the use of orientational distributions from molecular dynamics simulation along with time and powder angle averaging. The total predicted lineshape anisotropy was calculated from the superposition of the lineshapes of all guests. The approach was applied to calculate the temperature dependent 13C NMR lineshape anisotropy of carbon dioxide in structure 1 clathrates. The paper presented the computational methodology and results and discussion. It was concluded that the resulting lineshapes were in good agreement with the experimental 13C NMR spectrum at each temperature. The method provided a uniform procedure to calculate the lineshapes at different temperatures and no prior assumptions about the nature of the motion of the guest in cages was required. 37 refs., 2 tabs., 3 figs.

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

Directory of Open Access Journals (Sweden)

Guillaume D.

1999-07-01

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

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.

Characterization of solid polymer dispersions of active pharmaceutical ingredients by 19F MAS NMR and factor analysis

Czech Academy of Sciences Publication Activity Database

Urbanová, Martina; Brus, Jiří; Šeděnková, Ivana; Policianová, Olivia; Kobera, Libor

2013-01-01

Roč. 100, 1 January (2013), s. 59-66 ISSN 1386-1425 R&D Projects: GA ČR GPP106/11/P426; GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : solid-state NMR * factor analysis * 19F MAS NMR Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 2.129, year: 2013

Incorporation of phosphorus guest ions in the calcium silicate phases of Portland cement from 31P MAS NMR spectroscopy.

Science.gov (United States)

Poulsen, Søren L; Jakobsen, Hans J; Skibsted, Jørgen

2010-06-21

Portland cements may contain small quantities of phosphorus (typically below 0.5 wt % P(2)O(5)), originating from either the raw materials or alternative sources of fuel used to heat the cement kilns. This work reports the first (31)P MAS NMR study of anhydrous and hydrated Portland cements that focuses on the phase and site preferences of the (PO(4))(3-) guest ions in the main clinker phases and hydration products. The observed (31)P chemical shifts (10 to -2 ppm), the (31)P chemical shift anisotropy, and the resemblance of the lineshapes in the (31)P and (29)Si MAS NMR spectra strongly suggest that (PO(4))(3-) units are incorporated in the calcium silicate phases, alite (Ca(3)SiO(5)) and belite (Ca(2)SiO(4)), by substitution for (SiO(4))(4-) tetrahedra. This assignment is further supported by a determination of the spin-lattice relaxation times for (31)P in alite and belite, which exhibit the same ratio as observed for the corresponding (29)Si relaxation times. From simulations of the intensities, observed in inversion-recovery spectra for a white Portland cement, it is deduced that 1.3% and 2.1% of the Si sites in alite and belite, respectively, are replaced by phosphorus. Charge balance may potentially be achieved to some extent by a coupled substitution mechanism where Ca(2+) is replaced by Fe(3+) ions, which may account for the interaction of the (31)P spins with paramagnetic Fe(3+) ions as observed for the ordinary Portland cements. A minor fraction of phosphorus may also be present in the separate phase Ca(3)(PO(4))(2), as indicated by the observation of a narrow resonance at delta((31)P) = 3.0 ppm for two of the studied cements. (31)P{(1)H} CP/MAS NMR spectra following the hydration of a white Portland cement show that the resonances from the hydrous phosphate species fall in the same spectral range as observed for (PO(4))(3-) incorporated in alite. This similarity and the absence of a large (31)P chemical shift ansitropy indicate that the hydrous (PO(4

13C and 29Si NMR as a probe to investigate polysiloxanes used in dental applications

International Nuclear Information System (INIS)

Silva, Naira Machado da; Tavares, Maria Ines B.

2001-01-01

The properties of dental mould polymeric materials are strongly influenced by the chemical structure of both the polymer and the catalyst used in the crosslink reaction between them. In order to characterize and suggest some modifications on the materials interfacial interactions, mixtures of Polymer-catalyst were prepared. The polymer and the catalyst chemical structures were obtained by 13 C, 1 H and 129 Si NMR analysis in solution state. From the solution NMR results it was obtained the structure of the polymer and the catalyst and also the kind of the crosslink reaction taken. The CPMAS 1 '3C NMR analysis in the solid state were used to identify chemical structure of the polymeric dental moulded sample. (author)

NMR studies of chemical structural variation of insoluble organic matter from different carbonaceous chondrite groups

Science.gov (United States)

Cody, George D.; Alexander, Conel M. O.'D.

2005-02-01

Solid-state 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic experiments have been performed on isolated meteoritic Insoluble Organic Matter (IOM) spanning four different carbonaceous chondrite meteorite groups; a CR2 (EET92042), a CI1 (Orgueil), a CM2 (Murchison), and the unique C2 meteorite, Tagish Lake. These solid state NMR experiments reveal considerable variation in bulk organic composition across the different meteorite group's IOM. The fraction of aromatic carbon increases as CR2 meteorite groups. Single pulse (SP) 13C magic angle spinning (MAS) NMR experiments reveal the presence of nanodiamonds with an apparent concentration ranking in the IOM of CR2 IOM of all four meteoritic IOM fractions are highly substituted. Fast spinning SP 1H MAS NMR spectral data combined with other NMR experimental data reveal that the average hydrogen content of sp 3 bonded carbon functional groups is low, requiring a high degree of aliphatic chain branching in each IOM fraction. The variation in chemistry across the meteorite groups is consistent with alteration by low temperature chemical oxidation. It is concluded that such chemistry principally affected the aliphatic moieties whereas the aromatic moieties and nanodiamonds may have been largely unaffected.

Pectins from apple pomace - characterization by 13C and 1H NMR spectroscopy

International Nuclear Information System (INIS)

Marcon, M.V.; Carneiro, P.I.B.; Wosiacki, G.; Beleski-Carneiro, E.; Petkowicz, C.L.O.

2005-01-01

Pectins were extracted from apple pomace flour with 5% (w/v) aqueous citric acid solutions under different time and temperature according to an experimental design (factorial 2 2 with triplicate of central point). Monosaccharide composition of fractions was determined by colorimetric analysis and gas chromatography. The structure of pectins was studied by NMR spectroscopy. The degree of esterification (DE=30.5-55.9), determined by FT-IR spectroscopy, was indirectly correlated with increasing temperature and time of extraction, showing that drastic conditions for extraction promote hydrolysis of esterified units. High content of galacturonic acid is consistent with the smooth region of the polysaccharide. 13 C and 1 H NMR spectroscopy confirmed the presence of uronic acids in the free and methyl ester forms. NMR data also showed the presence of arabinan and galactan as side chains. (author)

A new Schiff base compound N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone): synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra.

Science.gov (United States)

Saheb, Vahid; Sheikhshoaie, Iran

2011-10-15

The Schiff base compound, N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone) (NDHA) is synthesized through the condensation of 2-hydroxylacetophenone and 2,2-dimethyl 1,3-amino propane in methanol at ambient temperature. The yellow crystalline precipitate is used for X-ray single-crystal determination and measuring Fourier transform infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP, PBEPBE and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the FTIR, (1)H NMR and (13)C NMR spectra of the compound. Time-dependent density functional theory (TDDFT) method is used to calculate the UV-visible spectrum of NDHA. Vibrational frequencies are determined experimentally and compared with those obtained theoretically. Vibrational assignments and analysis of the fundamental modes of the compound are also performed. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR and (13)C NMR chemical shifts calculated by all DFT methods are consistent with the experimental data. However, the NMR shielding tensors computed at the B3LYP/6-31+G(d,p) level of theory are in better agreement with experimental (1)H NMR and (13)C NMR spectra. The electronic absorption spectrum calculated at the B3LYP/6-31+G(d,p) level by using TD-DFT method is in accordance with the observed UV-visible spectrum of NDHA. In addition, some quantum descriptors of the molecule are calculated and conformational analysis is performed and the results were compared with the crystallographic data. Copyright © 2011 Elsevier B.V. All rights reserved.

Direct observation of glycogen synthesis in human muscle with 13C NMR

International Nuclear Information System (INIS)

Jue, T.; Rothman, D.L.; Shulman, G.I.; Tavitian, B.A.; DeFronzo, R.A.; Shulman, R.G.

1989-01-01

On the basis of previous indirect measurements, skeletal muscle has been implicated as the major site of glucose uptake and it has been suggested that muscle glycogen formation is the dominant pathway. However, direct measurements of the rates of glycogen synthesis have not been possible by previous techniques. The authors have developed 13 C NMR methods to measure directly the rate of human muscle glycogen formation from infused, isotopically labeled [1- 13 C]glucose. They show that under conditions of imposed hyperglycemia and hyperinsulinemia, a majority of the infused glucose was converted to muscle glycogen in a normal man. This directly shows that muscle is the major site of glucose disposal under these conditions, and provides quantitation of the glucose flux to muscle glycogen

XRD and solid state 13C-NMR evaluation of the crystallinity enhancement of 13C-labeled bacterial cellulose biosynthesized by Komagataeibacter xylinus under different stimuli: A comparative strategy of analyses.

Science.gov (United States)

Meza-Contreras, Juan C; Manriquez-Gonzalez, Ricardo; Gutiérrez-Ortega, José A; Gonzalez-Garcia, Yolanda

2018-05-22

The production and crystallinity of 13 C bacterial cellulose (BC) was examined in static culture of Komagataeibacter xylinus with different chemical and physical stimuli: the addition of NaCl or cloramphenicol as well as exposure to a magnetic field or to UV light. Crystalline BC biosynthesized under each stimulus was studied by XRD and solid state 13 C NMR analyses. All treatments produced BC with enhanced crystallinity over 90% (XRD) and 80% (NMR) compared to the control (83 and 76%, respectively) or to Avicel (77 and 62%, respectively). The XRD data indicated that the crystallite size was 80-85 Å. Furthermore, changes on the allomorphs (I α and I β ) ratio tendency of BC samples addressed to the stimuli were estimated using the C4 signal from 13 C NMR data. These results showed a decrease of the allomorph I α (3%) when BC was biosynthesized with UV light and chloramphenicol compared to control (58.79%). In contrast, the BC obtained with NaCl increased up to 60.31% of the I α allomorph ratio. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sensitivity and Resolution Enhanced Solid-State NMR for Paramagnetic Systems and Biomolecules under Very Fast Magic Angle Spinning

KAUST Repository

Parthasarathy, Sudhakar

2013-09-17

Recent research in fast magic angle spinning (MAS) methods has drastically improved the resolution and sensitivity of NMR spectroscopy of biomolecules and materials in solids. In this Account, we summarize recent and ongoing developments in this area by presenting (13)C and (1)H solid-state NMR (SSNMR) studies on paramagnetic systems and biomolecules under fast MAS from our laboratories. First, we describe how very fast MAS (VFMAS) at the spinning speed of at least 20 kHz allows us to overcome major difficulties in (1)H and (13)C high-resolution SSNMR of paramagnetic systems. As a result, we can enhance both sensitivity and resolution by up to a few orders of magnitude. Using fast recycling (∼ms/scan) with short (1)H T1 values, we can perform (1)H SSNMR microanalysis of paramagnetic systems on the microgram scale with greatly improved sensitivity over that observed for diamagnetic systems. Second, we discuss how VFMAS at a spinning speed greater than ∼40 kHz can enhance the sensitivity and resolution of (13)C biomolecular SSNMR measurements. Low-power (1)H decoupling schemes under VFMAS offer excellent spectral resolution for (13)C SSNMR by nominal (1)H RF irradiation at ∼10 kHz. By combining the VFMAS approach with enhanced (1)H T1 relaxation by paramagnetic doping, we can achieve extremely fast recycling in modern biomolecular SSNMR experiments. Experiments with (13)C-labeled ubiquitin doped with 10 mM Cu-EDTA demonstrate how effectively this new approach, called paramagnetic assisted condensed data collection (PACC), enhances the sensitivity. Lastly, we examine (13)C SSNMR measurements for biomolecules under faster MAS at a higher field. Our preliminary (13)C SSNMR data of Aβ amyloid fibrils and GB1 microcrystals acquired at (1)H NMR frequencies of 750-800 MHz suggest that the combined use of the PACC approach and ultrahigh fields could allow for routine multidimensional SSNMR analyses of proteins at the 50-200 nmol level. Also, we briefly discuss the

Microscopic structural analysis of fractured silk fibers from Bombyx mori and Samia cynthia ricini using 13C CP/MAS NMR with a 1 mm microcoil MAS NMR probehead

KAUST Repository

Yamauchi, Kazuo; Yamasaki, Shizuo; Takahashi, Rui; Asakura, Tetsuo

2010-01-01

Conformational changes have been studied in silk fibers from the domestic silkworm Bombyx mori and a wild silkworm Samia cynthia ricini as a result of fractured by stretching. About 300 samples consisting of only the fractured regions of [1-13C

Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

Science.gov (United States)

Zhang, Z T; Xu, C; Dmytriieva, D; Molatta, S; Wosnitza, J; Wang, Y T; Helm, M; Zhou, Shengqiang; Kühne, H

2017-10-20

We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13 C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13 C nuclear spin-lattice relaxation rate [Formula: see text] by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of [Formula: see text] below about 10 K can well be described by a thermally activated form, [Formula: see text], yielding a singular Zeeman energy of ([Formula: see text]) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments.

Structural characteristics of marine sedimentary humic acids by CP/MAS sup(13)C NMR spectroscopy

Digital Repository Service at National Institute of Oceanography (India)

Sardessai, S.; Wahidullah, S.

quino- nes or semiquinones which exhibit 13C resonance at around 195 ppm. Free radicals of semiquinone type have been reported from the aquatic environment [2]. Spectra of all the four samples show absorption at 195 ppm. The total acidity of marine..., significant resonance at 55 ppm (8.9) from aromatic methoxy carbon suggests that phenol is present mostly as methyl ether and not as free phenol. The signal at 55 ppm is also attributed to aliphatic carbon adjacent to the amino functional group as in amino...

Positional enrichment by proton analysis (PEPA). A one-dimensional "1H-NMR approach for "1"3C stable isotope tracer studies in metabolomics

International Nuclear Information System (INIS)

Vinaixa, Maria; Yanes, Oscar; Rodriguez, Miguel A.; Capellades, Jordi; Aivio, Suvi; Stracker, Travis H.; Gomez, Josep; Canyellas, Nicolau

2017-01-01

A novel metabolomics approach for NMR-based stable isotope tracer studies called PEPA is presented, and its performance validated using human cancer cells. PEPA detects the position of carbon label in isotopically enriched metabolites and quantifies fractional enrichment by indirect determination of "1"3C-satellite peaks using 1D-"1H-NMR spectra. In comparison with "1"3C-NMR, TOCSY and HSQC, PEPA improves sensitivity, accelerates the elucidation of "1"3C positions in labeled metabolites and the quantification of the percentage of stable isotope enrichment. Altogether, PEPA provides a novel framework for extending the high-throughput of "1H-NMR metabolic profiling to stable isotope tracing in metabolomics, facilitating and complementing the information derived from 2D-NMR experiments and expanding the range of isotopically enriched metabolites detected in cellular extracts. (copyright 2017 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

Structural characterization of heat treated pitch by solid state /sup 13/C nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sfihi, H.; Tougne, P.; Legrand, A.P.; Couderc, P.; Saint-Romain, J.L.

1988-12-01

The objective of this paper is to determine structural parameters (aromaticity factor, fractions of protonated and non-protonated aromatic carbons) of some pitches, and to follow their evolution as a function of the heat treatment duration. For such a determination, /sup 13/C-/sup 1/H cross polarization combined with magic angle spinning and dipolar dephasing (CP/MAS/DD) NMR was used. 15 refs., 4 figs., 1 tab.

Sub-minute kinetics of human red cell fumarase: 1 H spin-echo NMR spectroscopy and 13 C rapid-dissolution dynamic nuclear polarization.

Science.gov (United States)

Shishmarev, Dmitry; Wright, Alan J; Rodrigues, Tiago B; Pileio, Giuseppe; Stevanato, Gabriele; Brindle, Kevin M; Kuchel, Philip W

2018-03-01

Fumarate is an important probe of metabolism in hyperpolarized magnetic resonance imaging and spectroscopy. It is used to detect the release of fumarase in cancer tissues, which is associated with necrosis and drug treatment. Nevertheless, there are limited reports describing the detailed kinetic studies of this enzyme in various cells and tissues. Thus, we aimed to evaluate the sub-minute kinetics of human red blood cell fumarase using nuclear magnetic resonance (NMR) spectroscopy, and to provide a quantitative description of the enzyme that is relevant to the use of fumarate as a probe of cell rupture. The fumarase reaction was studied using time courses of 1 H spin-echo and 13 C-NMR spectra. 1 H-NMR experiments showed that the fumarase reaction in hemolysates is sufficiently rapid to make its kinetics amenable to study in a period of approximately 3 min, a timescale characteristic of hyperpolarized 13 C-NMR spectroscopy. The rapid-dissolution dynamic nuclear polarization (RD-DNP) technique was used to hyperpolarize [1,4- 13 C]fumarate, which was injected into concentrated hemolysates. The kinetic data were analyzed using recently developed FmR α analysis and modeling of the enzymatic reaction using Michaelis-Menten equations. In RD-DNP experiments, the decline in the 13 C-NMR signal from fumarate, and the concurrent rise and fall of that from malate, were captured with high spectral resolution and signal-to-noise ratio, which allowed the robust quantification of fumarase kinetics. The kinetic parameters obtained indicate the potential contribution of hemolysis to the overall rate of the fumarase reaction when 13 C-NMR RD-DNP is used to detect necrosis in animal models of implanted tumors. The analytical procedures developed will be applicable to studies of other rapid enzymatic reactions using conventional and hyperpolarized substrate NMR spectroscopy. Copyright © 2018 John Wiley & Sons, Ltd.

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.

Estimation of glucose carbon recycling in children with glycogen storage disease: A 13C NMR study using [U-13C]glucose

International Nuclear Information System (INIS)

Kalderon, B.; Korman, S.H.; Gutman, A.; Lapidot, A.

1989-01-01

A stable isotope procedure to estimate hepatic glucose carbon recycling and thereby elucidate the mechanism by which glucose is produced in patients lacking glucose 6-phosphatase is described. A total of 10 studies was performed in children with glycogen storage disease type I (GSD-I) and type III (GSD-III) and control subjects. A primed dose-constant nasogastric infusion of D-[U- 13 C]glucose or an infusion diluted with nonlabeled glucose solution was administered following different periods of fasting. Hepatic glucose carbon recycling was estimated from 13 C NMR spectra. The values obtained for GSD-I patients coincided with the standard [U- 13 C]glucose dilution curve. These results indicate that the plasma glucose of GSD-I subjects comprises only a mixture of 99% 13 C-enriched D-[U- 13 C]glucose and unlabeled glucose but lacks any recycled glucose. Significantly different glucose carbon recycling values were obtained for two GSD-III patients in comparison to GSD-I patients. The results eliminate a mechanism for glucose production in GSD-I children involving gluconeogenesis. However, glucose release by amylo-1,6-glucosidase activity would result in endogenous glucose production of non- 13 C-labeled and nonrecycled glucose carbon, as was found in this study. In GSD-III patients gluconeogenesis is suggested as the major route for endogenous glucose synthesis. The contribution of the triose-phosphate pathway in these patients has been determined

Experiments and strategies for the assignment of fully13 C/15N-labelled polypeptides by solid state NMR

International Nuclear Information System (INIS)

Straus, Suzana K.; Bremi, Tobias; Ernst, Richard R.

1998-01-01

High-resolution heteronuclear NMR correlation experiments and strategies are proposed for the assignment of fully 13 C/ 15 N-labelled polypeptides in the solid state. By the combination of intra-residue and inter-residue 13 C- 15 N correlation experiments with 13 C- 13 C spin-diffusion studies, it becomes feasible to partially assign backbone and side-chain resonances in solid proteins. The performance of sequences using 15 N instead of 13 C detection is evaluated regarding sensitivity and resolution for a labelled dipeptide (L-Val-L-Phe). The techniques are used for a partial assignment of the 15 N and 13 C resonances in human ubiquitin

Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

Science.gov (United States)

Zhang, Zhi Tao; Xu, C; Dmytriieva, Daryna; Molatta, Sebastian; Wosnitza, J; Wang, Y T; Helm, Manfred; Zhou, Shengqiang; Kuehne, Hannes

2017-09-18

We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by $^{13}$C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the $^{13}$C nuclear spin-lattice relaxation rate $1/T_{1}$ by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of $1/T_{1}$ below about 10 K can well be described by a thermally activated form, $1/T_{1}\\propto\\exp(-\\Delta/k_{B}T)$, yielding a singular Zeeman energy of ($0.41\\pm0.01$) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments. © 2017 IOP Publishing Ltd.

Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

International Nuclear Information System (INIS)

Clark, D.L.; Hobart, D.E.; Palmer, P.D.; Sullivan, J.C.; Stout, B.E.

1992-01-01

The uranyl(VI) carbonate system has been re-examined using 13 C NMR of 99.9% 13 C-enriched U VI O 2 ( 13 CO 3 ) 3 4- in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu VI O 2 ( 13 CO 3 ) 3 4- and Am VI O 2 ( 13 CO 3 ) 3 4- systems has been examined by variable temperature 13 C NMR line-broadening techniques 13 C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of ΔG double-dagger 295 = 56 kJ/M, ΔH double-dagger = 38 kJ/M, and ΔS double-dagger = -60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress

13C NMR and relaxation studies of the nanomagnet Mn12-acetate

Science.gov (United States)

Achey, Randall M.; Kuhns, Philip L.; Reyes, Arneil P.; Moulton, William G.; Dalal, Naresh S.

2001-08-01

The nanomagnet [Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O, also known as Mn12, has been synthesized with 13C labeling at the CH3 groups, and investigated by 13C NMR at fields up to 23 T. Using oriented samples, it is possible to resolve four distinct 13C peaks at room temperature, located on both sides of the unshifted Larmor frequency. These peaks were assigned to the four hyperfine-shifted, magnetically inequivalent sets of 13CH3 groups in the Mn12 lattice, based on a comparison with the crystal structure and point-dipole and spin-density calculations. These results establish that the unpaired electron spin density of the S=10 system in this cluster extends over the entire molecular framework, not just the core. These results are discussed in relationship to inelastic neutron scattering measurements. The temperature and field dependence of the 13C nuclear-spin-lattice-relaxation time T1 on the least shifted peak was measured. A single weakly field-dependent minimum at about 60 K is observed in the temperature dependence of the measured T1. The relaxation mechanism responsible for the T1 minimum is ascribed mainly to hindered rotation of the methyl group of the acetate ligand at higher temperature, and to electronic spin fluctuations at lower temperature.

1H MAS NMR (magic-angle spinning nuclear magnetic resonance) techniques for the quantitative determination of hydrogen types in solid catalysts and supports.

Science.gov (United States)

Kennedy, Gordon J; Afeworki, Mobae; Calabro, David C; Chase, Clarence E; Smiley, Randolph J

2004-06-01

Distinct hydrogen species are present in important inorganic solids such as zeolites, silicoaluminophosphates (SAPOs), mesoporous materials, amorphous silicas, and aluminas. These H species include hydrogens associated with acidic sites such as Al(OH)Si, non-framework aluminum sites, silanols, and surface functionalities. Direct and quantitative methodology to identify, measure, and monitor these hydrogen species are key to monitoring catalyst activity, optimizing synthesis conditions, tracking post-synthesis structural modifications, and in the preparation of novel catalytic materials. Many workers have developed several techniques to address these issues, including 1H MAS NMR (magic-angle spinning nuclear magnetic resonance). 1H MAS NMR offers many potential advantages over other techniques, but care is needed in recognizing experimental limitations and developing sample handling and NMR methodology to obtain quantitatively reliable data. A simplified approach is described that permits vacuum dehydration of multiple samples simultaneously and directly in the MAS rotor without the need for epoxy, flame sealing, or extensive glovebox use. We have found that careful optimization of important NMR conditions, such as magnetic field homogeneity and magic angle setting are necessary to acquire quantitative, high-resolution spectra that accurately measure the concentrations of the different hydrogen species present. Details of this 1H MAS NMR methodology with representative applications to zeolites, SAPOs, M41S, and silicas as a function of synthesis conditions and post-synthesis treatments (i.e., steaming, thermal dehydroxylation, and functionalization) are presented.

Selective and extensive 13C labeling of a membrane protein for solid-state NMR investigations

International Nuclear Information System (INIS)

Hong, M.; Jakes, K.

1999-01-01

The selective and extensive 13C labeling of mostly hydrophobic amino acid residues in a 25 kDa membrane protein, the colicin Ia channel domain, is reported. The novel 13C labeling approach takes advantage of the amino acid biosynthetic pathways in bacteria and suppresses the synthesis of the amino acid products of the citric acid cycle. The selectivity and extensiveness of labeling significantly simplify the solid-state NMR spectra, reduce line broadening, and should permit the simultaneous measurement of multiple structural constraints. We show the assignment of most 13C resonances to specific amino acid types based on the characteristic chemical shifts, the 13C labeling pattern, and the amino acid composition of the protein. The assignment is partly confirmed by a 2D homonuclear double-quantum-filter experiment under magic-angle spinning. The high sensitivity and spectral resolution attained with this 13C-labeling protocol, which is termed TEASE for ten-amino acid selective and extensive labeling, are demonstrated

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 pH variation have been observed for the parent barbituric acid.

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

International Nuclear Information System (INIS)

Werner, I.; Bacher, A.; Eisenreich, W.

1997-01-01

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

Metallic nature of Sn{sub 1-} {sub x} Sb {sub x} O{sub 2{+-}} {sub {delta}} (x=0.0, 0.10 and 0.20) mixed oxides: Probed by {sup 119}Sn MAS NMR

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, O.D. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)]. E-mail: ddjaya@apsara.barc.ernet.in; Sudarsan, V. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kulshreshtha, S.K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2007-04-15

Antimony doped SnO{sub 2} samples were prepared by co-precipitation method and characterized by X-ray diffraction (XRD), {sup 119}Sn magic angle spinning nuclear magnetic resonance (MAS NMR) and variable temperature electrical conductivity measurements. Based on {sup 119}Sn MAS NMR measurements on these samples, it was established that only above 400 deg. C, the structural units of antimony and tin interacts, resulting in the metallic nature. Metallic behavior of the high-temperature heated samples was further confirmed by the variable temperature electrical conductivity measurements.

Site-specific 13C content by quantitative isotopic 13C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

International Nuclear Information System (INIS)

Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S.

2013-01-01

Graphical abstract: -- Highlights: •First ring test on isotopic 13 C NMR spectrometry. •Evaluation of the intra- and inter-variability of the NMR spectrometers used. •Definition of a protocol for qualification of the performance of the spectrometer. -- Abstract: Isotopic 13 C NMR spectrometry, which is able to measure intra-molecular 13 C composition, is of emerging demand because of the new information provided by the 13 C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic 13 C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular 13 C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic 13 C NMR was then assessed on vanillin from three different origins associated with specific δ 13 C i profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ 13 C i in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results

Conformational analysis of 9,10-dihydroanthracenes. Molecular mechanics calculations and /sup 13/C NMR

Energy Technology Data Exchange (ETDEWEB)

Rabideau, P.W.; Mooney, J.L.; Lipkowitz, K.B.

1986-12-24

The conformational analyses of 9, 10-dihydroanthracene and several of its methylated and ethylated derivatives are studied by empirical force field calculations (MM2 and MMPI). The computational results are considered in light of previous and current carbon NMR data. Model compounds are examined which involve fixed, planar, and boat-shaped conformations about the central ring, and these /sup 13/C NMR data are then compared with flexible systems. It is concluded that carbon chemical shifts and carbon-hydrogen coupling constants are consistent with the results of molecular mechanics calculations which indicate a greater tendency for planarity around the central ring than previously considered.

Effect of Ge/Si substitutions on the local geometry of Si framework sites in zeolites: A combined high resolutionsup29/supSi MAS NMR and DFT/MM study on zeolite Beta polymorph C (BEC)

Czech Academy of Sciences Publication Activity Database

Whittleton, Sarah R.; Vicente, A.; Fernandez, C.; Rastegar, Somayeh F.; Fishchuk, Anna V.; Sklenák, Štěpán

2018-01-01

Roč. 267, SEP 2018 (2018), s. 124-133 ISSN 1387-1811 R&D Projects: GA ČR(CZ) GA15-14007S Grant - others:Ga MŠk(CZ) LM2015070 Institutional support: RVO:61388955 Keywords : 29 Si MAS NMR * bec * Ge-zeolites * Germanoaluminosilicates * Zeolite Beta polymorph C Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.615, year: 2016

Positional enrichment by proton analysis (PEPA). A one-dimensional {sup 1}H-NMR approach for {sup 13}C stable isotope tracer studies in metabolomics

Energy Technology Data Exchange (ETDEWEB)

Vinaixa, Maria; Yanes, Oscar [Department of Electronic Engineering-Universitat Rovira i Virgili, Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus (Spain); Rodriguez, Miguel A.; Capellades, Jordi [Universitat Rovira i Virgili, Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus (Spain); Aivio, Suvi; Stracker, Travis H. [Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (Spain); Gomez, Josep; Canyellas, Nicolau [Department of Electronic Engineering-, Universitat Rovira i Virgili, Tarragona (Spain)

2017-03-20

A novel metabolomics approach for NMR-based stable isotope tracer studies called PEPA is presented, and its performance validated using human cancer cells. PEPA detects the position of carbon label in isotopically enriched metabolites and quantifies fractional enrichment by indirect determination of {sup 13}C-satellite peaks using 1D-{sup 1}H-NMR spectra. In comparison with {sup 13}C-NMR, TOCSY and HSQC, PEPA improves sensitivity, accelerates the elucidation of {sup 13}C positions in labeled metabolites and the quantification of the percentage of stable isotope enrichment. Altogether, PEPA provides a novel framework for extending the high-throughput of {sup 1}H-NMR metabolic profiling to stable isotope tracing in metabolomics, facilitating and complementing the information derived from 2D-NMR experiments and expanding the range of isotopically enriched metabolites detected in cellular extracts. (copyright 2017 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

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. Copyright © 2016 Elsevier B.V. All rights reserved.

A 13C NMR Study of 7-Norbornadienyl Cation by Modified Hammett-Brown Equation

International Nuclear Information System (INIS)

Park, Jeong Kyu; Shin, Jung Hyu

1999-01-01

A series of the para-substituted 7-aryl-norbornadienyl cation (3) was prepared in FSO 3 H/SO 2 ClF solution at -100 .deg. C and their 13 C NMR shifts were measured at -80 .deg. C. The plots of the chemical shifts (changes in chemical shifts) of cationic carbon, Δδ C+ , against our calculated new substituent constant, σ c+ s, gave an excellent correlation (r = 0.994), with a p c+ value of 12.63. These results indicate that the new substituent onstants, σ c+ s, can be successfully employed to compare the relative charge demand of the carbonium ion by π- and πσ-participation

Complete {sup 1}H and {sup 13}C NMR structural assignments for a group of four goyazensolide-type furanoheliangolides

Energy Technology Data Exchange (ETDEWEB)

Soares, Ana Carolina Ferreira; Silva, Aline Nazare; Matos, Priscilla Mendonca; Silva, Eder Henrique da; Heleno, Vladimir Constantino Gomes [Universidade de Franca, Franca, SP (Brazil). Nucleo de Pesquisas em Ciencias Exatas e Tecnologicas; Lopes, Norberto Peporine; Lopes, Joao Luis Callegari [Universidade de Sao Paulo (FCFRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Ciencias Farmaceuticas de Ribeirao Preto. Dept. de Quimica e Fisica; Sass, Daiane Cristina, E-mail: vheleno_05@yahoo.com.br [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Filosofia, Ciencias e Letras de Ribeirao Preto. Dept. de Quimica

2012-07-01

Four goyazensolide-type sesquiterpene lactones - lychnofolide, centratherin, goyazensolide and goyazensolide acetate - were thoroughly studied by NMR experimental techniques. {sup 1}H NMR, {sup 13}C NMR {l_brace}{sup 1}H{r_brace}, COSY, HMQC, HMBC, J-res. and NOE experiments were performed to provide the needed structural information. Complete and unequivocal assignment, including the determination of all multiplicities, was obtained for each structure and the data collections are presented in tables (author)

Experimental (FT-IR, FT-Raman, 1H, 13C NMR) and theoretical study of alkali metal 2-aminobenzoates

Science.gov (United States)

Samsonowicz, M.; Świsłocka, R.; Regulska, E.; Lewandowski, W.

2008-09-01

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-aminobenzoic acid was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-aminobenzoic acid and its alkali metal salts were recorded. The assignment of vibrational spectra was done on the basis of literature data, theoretical calculations and our previous experience. Characteristic shifts of bands and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons ( 1H NMR) and carbons ( 13C NMR) in the series of studied alkali metal 2-aminobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G ∗∗ basis set. Geometric aromaticity indices, dipole moments and energies were also calculated. The theoretical wavenumbers and intensities of IR and Raman spectra were obtained. The calculated parameters were compared to experimental characteristic of studied compounds.

Synthesis of 24-methyl sterols sterospecifically labelled with 2H in the isopropyl methyl groups. 13C NMR spectral assignment of C-26 and C-27 resonances

International Nuclear Information System (INIS)

Colombo, D.; Ronchetti, F.; Toma, L.

1990-01-01

Through analysis of the 13 C NMR spectra of (25S)-[27- 2 H]campesterol (1) and (25R)-[26- 2 H]dihydrobrassicasterol (2), the C-26 and C-27 resonances have been unambiguously assigned; the biosynthetic applications are discussed. (author)

Chemical profile of beans cultivars (Phaseolus vulgaris) by 1H NMR - high resolution magic angle spinning (HR-MAS);Perfil quimico de cultivares de feijao (Phaseolus vulgaris) pela tecnica de high resolution magic angle spinning (HR-MAS)

Energy Technology Data Exchange (ETDEWEB)

Liao, Luciano Morais; Choze, Rafael; Cavalcante, Pedro Paulo Araujo; Santos, Suzana da Costa; Ferri, Pedro Henrique, E-mail: luciano@quimica.ufg.b [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Inst. de Quimica; Ferreira, Antonio Gilberto [Universidade Federal de Sao Carlos (UFScar), SP (Brazil). Dept. de Quimica

2010-07-01

The application of one-dimensional proton high-resolution magic angle spinning ({sup 1}H HR-MAS) NMR combined with a typical advantages of solid and liquid-state NMR techniques was used as input variables for the multivariate statistical analysis. In this paper, different cultivars of beans (Phaseolus vulgaris) developed and in development by EMBRAPA - Arroz e Feijao were analyzed by {sup 1}H HR-MAS, which have been demonstrated to be a valuable tool in its differentiation according chemical composition and avoid the manipulation of the samples as used in other techniques. (author)

One-azabicyclic compounds. 22. Stereochemistry and /sup 13/C NMR spectra of salts of pyrrolizidine and its homologs with protonic acids

Energy Technology Data Exchange (ETDEWEB)

Subbotin, O.A.; Skvortsov, I.M.

1986-06-01

/sup 13/C NMR spectra were obtained for pyrrolizidinium salts and their homologs and their signals were assigned. With the exception of highly strained cis-3,8-H-cis-5,8-H-3,5-dimethylpyrrolizidine (VI), all the bases studied upon their direct mixing with CF/sub 3/CO/sub 2/H form salts only with cis-fused rings in the cation. Mixtures of salts with cis- and trans-fused pyrrolizidinium fragments are formed upon the reaction of cis-3,8-H-methyl- (III) and cis-3,8-H-cis-5,8-H-3,5-dimethylpyrrolizidine (VI) under conditions close to those for kinetically-controlled amine protonation. The /sup 13/C NMR spectra of the isomeric pyrrolizidinium salts obtained as a result of the absorption of base VI by sulfuric acid were used to evaluate the conformational equilibrium in the starting compound VI. The /sup 13/C NMR chemical shifts of unsubstituted trans-fused pyrrolizidinium salts were predicted.

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

DEFF Research Database (Denmark)

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

2005-01-01

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

Metabolic engineering applications of in vivo 31P and 13C NMR studies of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Shanks, J.V.

1989-01-01

With intent to quantify NMR measurements as much as possible, analysis techniques of the in vivo 31 P NMR spectrum are developed. A systematic procedure is formulated for estimating the relative intracellular concentrations of the sugar phosphates in S. cerevisiae from the 31 P NMR spectrum. In addition, in vivo correlation of inorganic phosphate chemical shift with the chemical shifts of 3-phosphoglycerate, β-fructose 1,6-diphosphate, fructose 6-phosphate, and glucose 6-phosphate are determined. Also, a method was developed for elucidation of the cytoplasmic and vacuolar components of inorganic phosphate in the 31 P NMR spectrum of S. cerevisiae. An in vivo correlation relating the inorganic phosphate chemical shift of the vacuole with the chemical shift of the resonance for pyrophosphate and the terminal phosphate of polyphosphate (PP 1 ) is established. Transient measurements provided by 31 P NMR are applied to reg1 mutant and standard strains. 31 P and 13 C NMR measurements are used to analyze the performance of recombinant strains in which the glucose phosphorylation step had been altered

Sensitivity enhancement of 13C nuclei in 2D J-resolved NMR spectroscopy using a recycled-flow system

International Nuclear Information System (INIS)

Ha, S.T.K.; Lee, R.W.K.; Wilkins, C.L.

1987-01-01

Recycled-flow nuclear magnetic resonance for sensitivity enhancement in 1/2 spin nuclei has been reported previously, achieving several-fold signal enhancement. The success of the method depends upon premagnetization of nuclei prior to flowing into the detector region, obviating the need for delays following data acquisition to allow spin-lattice relaxation and reduce experiment time. The actual gains of sensitivity enhancement for 13 C- 1 H 2D J-resolved NMR using a recycled-flow method are evaluated. Possible enhancements for two types of J-resolved measurements, namely, one-bond 13 C- 1 H and long range J-resolved spectroscopy, are estimated using a simple Carr-Purcell spin-echo approach to quantify the 13 C signals. The pulse sequence is simply 90 0 -t /sub 1/2/-180 0 -t/sub 1/2/-AT-t/sub d/, where t/sub 1/2/ is half the evolution time, AT is the acquisition time, and t/sub d/ the experiment repetition time. In a static 2D NMR experiment, t/sub d/ usually must be the same order of the longest spin-lattice relaxation time (T 1 ) of nuclei. Quantitative measurements using a recycled-flow system indicate t/dub d/ can be reduced to a fraction of T 1 ; hence significant time savings can be achieved. Time-savings of between 2 and 25 can be anticipated for 2D spectroscopy under flow measurement conditions used in the present study. Other types of 2D NMR spectroscopy (autocorrelation and double quantum NMR) are discussed

Ab initio/GIAO-CCSD(T) study of structures, energies, and 13C NMR chemical shifts of C4H7(+) and C5H9(+) ions: relative stability and dynamic aspects of the cyclopropylcarbinyl vs bicyclobutonium ions.

Science.gov (United States)

Olah, George A; Surya Prakash, G K; Rasul, Golam

2008-07-16

The structures and energies of the carbocations C 4H 7 (+) and C 5H 9 (+) were calculated using the ab initio method. The (13)C NMR chemical shifts of the carbocations were calculated using the GIAO-CCSD(T) method. The pisigma-delocalized bisected cyclopropylcarbinyl cation, 1 and nonclassical bicyclobutonium ion, 2 were found to be the minima for C 4H 7 (+) at the MP2/cc-pVTZ level. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level the structure 2 is 0.4 kcal/mol more stable than the structure 1. The (13)C NMR chemical shifts of 1 and 2 were calculated by the GIAO-CCSD(T) method. Based on relative energies and (13)C NMR chemical shift calculations, an equilibrium involving the 1 and 2 in superacid solutions is most likely responsible for the experimentally observed (13)C NMR chemical shifts, with the latter as the predominant equilibrating species. The alpha-methylcyclopropylcarbinyl cation, 4, and nonclassical bicyclobutonium ion, 5, were found to be the minima for C 5H 9 (+) at the MP2/cc-pVTZ level. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level ion 5 is 5.9 kcal/mol more stable than the structure 4. The calculated (13)C NMR chemical shifts of 5 agree rather well with the experimental values of C 5H 9 (+).

13C and 31P NMR [Nuclear Magnetic Resonance] studies of prostate tumor metabolism

International Nuclear Information System (INIS)

Sillerud, L.O.; Halliday, K.R.; Freyer, J.P; Griffey, R.H.; Fenoglio-Preiser, C.

1989-01-01

The current research on prostate cancer by NMR spectroscopy and microscopy will most significantly contribute to tumor diagnosis and characterization only if sound biochemical models of tumor metabolism are established and tested. Prior searches focused on universal markers of malignancy, have to date, revealed no universal markers by any method. It is unlikely that NMRS will succeed where other methods have failed, however, NMR spectroscopy does provide a non-invasive means to analyze multiple compounds simultaneously in vivo. In order to fully evaluate the ability of NMRS to differentiate non-malignant from malignant tissues it is necessary to determine sufficient multiple parameters from specific, well-diagnosed, histological tumor types that, in comparison to normal tissue and non-neoplastic, non-normal pathologies from which the given neoplasm must be differentiated, one has enough degrees of freedom to make a mathematically and statistically significant determination. Confounding factors may consist of tumor heterogeneity arising from regional variations in differentiation, ischemia, necrosis, hemorrhage, inflammation and the presence of intermingled normal tissue. One related aspect of our work is the development of { 13 C}- 1 H metabolic imaging of 13 C for metabolic characterization, with enhanced spatial localization (46). This should markedly extend the range of potential clinical NMR uses because the spatial variation in prostate metabolism may prove to be just as important in tumor diagnoses as bulk (volume-averaged) properties themselves. It is our hope that NMRS and spectroscopic imaging will reveal a sound correlation between prostate metabolism and tumor properties that will be clinically straightforward and useful for diagnosis

A preliminary study of the relation between adsorption and CP-MAS-NMR characteristics of fused silica model substrates

NARCIS (Netherlands)

Scholten, A.B.; Janssen, J.G.M.; Haan, de J.W.; Cramers, C.A.M.G.; Sandra, P.J.F.; Devos, G.; Sandra, P.

1993-01-01

The fumed silica model substrate Aerosil was trimethylsilylated to different extents and studied by the combination of IGC and 29Si CP-MAS-NMR. Dihydroxydisiloxane groups were shown to be chemically more reactive than monohydroxytrisiloxane groups. Chromatographic experiments showed that these

13C-NMR reveals glycerol as an unexpected major metabolite of the protozoan parasite Trichomonas vaginalis

International Nuclear Information System (INIS)

Chapman, A.; Lloyd, D.; Linstead, D.J.; Williams, J.

1985-01-01

13 C-NMR has been used to study the kinetics of the formation of metabolites from [l- 13 C]glucose in intact cells of Trichomonas vaginalis during anaerobic incubation. As well as the expected metabolites lactate and acetate, this technique revealed glycerol as an additional major product, present in amounts equimolar with acetate. The formation of glycerol is readily explained in terms of the need to maintain redox balance. This protozoan now joins the small group of organisms which are known to produce glycerol as a result of normal metabolic activities. (Auth.)

Analysis of neuron–astrocyte metabolic cooperation in the brain of db/db mice with cognitive decline using 13C NMR spectroscopy

OpenAIRE

Zheng, Hong; Zheng, Yongquan; Wang, Dan; Cai, Aimin; Lin, Qiuting; Zhao, Liangcai; Chen, Minjiang; Deng, Mingjie; Ye, Xinjian; Gao, Hongchang

2016-01-01

Type 2 diabetes has been linked to cognitive impairment, but its potential metabolic mechanism is still unclear. The present study aimed to explore neuron–astrocyte metabolic cooperation in the brain of diabetic (db/db, BKS.Cg-m+/+ Leprdb/J) mice with cognitive decline using 13C NMR technique in combination with intravenous [2-13C]-acetate and [3-13C]-lactate infusions. We found that the 13C-enrichment from [2-13C]-acetate into tricarboxylic acid cycle intermediate, succinate, was significant...

Partial least squares modeling of combined infrared, 1H NMR and 13C NMR spectra to predict long residue properties of crude oils

NARCIS (Netherlands)

de Peinder, P.; Visser, T.; Petrauskas, D.D.; Salvatori, F.; Soulimani, F.; Weckhuysen, B.M.

2009-01-01

Research has been carried out to determine the potential of partial least squares (PLS) modeling of mid-infrared (IR) spectra of crude oils combined with the corresponding 1H and 13C nuclear magnetic resonance (NMR) data, to predict the long residue (LR) properties of these substances. The study

Polysaccharides of algae. Pt. 37. Characterization of hybrid structure of substituted agarose from Polysiphonia morrowii (Rhodophyta, Rhodomelaceae) using. beta. -agarase and /sup 13/C-NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Usov, A.I.; Ivanova, E.G.

1987-09-01

Structure of gel-forming galactan from Polysiphonia morrowii was analysed using bacterial ..beta..-agarase and /sup 13/C-nuclear magnetic resonance (/sup 13/C-NMR) spectroscopy. The polysaccharide was shown to contain: a) blocks composed of agarobiose residues, partly 6-O-methylated and 6-sulfated, which are sensitive to enzymolysis; b) extended blocks composed of agarobiose 6-sulfate residues, which are resistant to ..beta..-agarase action. The latter blocks contain also ..beta..-D-galactopyranosyl-(1->4)-..cap alpha..-L-galactopyranose 6.6'-disulfate residues (biogenetic precursors of agarobiose 6-sulfate), which are hardly detectable by /sup 13/C-NMR spectrum of the starting polysaccharide. Action of alkali on the enzyme-resistant fraction afforded a polysaccharide preparation having /sup 13/C-NMR spectrum of agarose 6-sulfate.

Heteronuclear three-dimensional NMR spectroscopy. Natural abundance 13C chemical shift editing of 1H-1H COSY spectra

International Nuclear Information System (INIS)

Fesik, S.W.; Gampe, R.T. Jr.; Zuiderweg, E.R.P.

1989-01-01

It has been demonstrated that heteronuclear 3D NMR spectroscopy can be effectively applied to small molecules with 13 C at natural abundance. A 78mM solution of the aminoglycoside, kanamycin A was used for this experiment. The heteronuclear 3D NMR spectroscopy is shown to be a useful method for resolving spectral overlap in all frequency domains. 10 refs., 2 figs

13C NMR and XPS characterization of anion adsorbent with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse

International Nuclear Information System (INIS)

Cao, Wei; Wang, Zhenqian; Zeng, Qingling; Shen, Chunhua

2016-01-01

Highlights: • 13 C NMR and XPS were successfully used to characterize quaternary ammonium groups in the surface of crop straw based anion adsorbents. • The results obtained from different kinds of crop straw material clearly confirmed the presence of quaternary ammonium groups. • The composition of C-groups and N-groups also were determined by curving fitting of high-resolution XPS C1 and N1 spectra. - Abstract: Despite amino groups modified crop straw has been intensively studied as new and low-cost adsorbent for removal of anionic species from water, there is still a lack of clear characterization for amino groups, especially quaternary ammonium groups in the surface of crop straw. In this study, we used 13 C NMR and XPS technologies to characterize adsorbents with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse. 13 C NMR spectra clearly showed the presence of quaternary ammonium groups in lignocelluloses structure of modified crop straw. The increase of nitrogen observed in XPS survey spectra also indicated the existence of quaternary ammonium group in the surface of the adsorbents. The curve fitting of high-resolution XPS N1s and C1s spectra were conducted to probe the composition of nitrogen and carbon contained groups, respectively. The results showed the proportion of quaternary ammonium group significantly increased in the prepared adsorbent’s surface that was dominated by methyl/methylene, hydroxyl, quaternary ammonium, ether and carbonyl groups. This study proved that 13 C NMR and XPS could be successfully utilized for characterization of quaternary ammonium modified crop straw adsorbents.

Antiferromagnetic Ordering in Quasi-Triangular Localized Spin System, β'-Et2Me2P[Pd(dmit)2]2, Studied by 13C NMR

Science.gov (United States)

Otsuka, Kei; Iikubo, Hideaki; Kogure, Takayuki; Takano, Yoshiki; Hiraki, Ko-ichi; Takahashi, Toshihiro; Cui, Hengbo; Kato, Reizo

2014-05-01

We performed 13C NMR measurements of a selectively 13C isotope-labeled single-crystal sample of a frustrated spin system, β'-Et2Me2P[Pd(dmit)2]2. A long-range antiferromagnetic (AF) ordering below 17 K was confirmed by the observation of NMR spectrum broadening and well split resonance lines at lower temperatures. NMR spectra in the AF state can be well explained by a two sublattice model. From the analysis of the angular dependence of the NMR spectrum, we clarified the magnetic structure in the AF state, where the easy and hard axes are the crystallographic c*- and b-axes, respectively, and the effective localized moments are quite small, ˜0.28 μB/dimer. This suggests a strong quantum fluctuation effect due to magnetic frustrations in a quasi-triangular spin-1/2 system.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Experimental and DFT evaluation of the 1H and 13C NMR chemical shifts for calix[4]arenes

Science.gov (United States)

Guzzo, Rodrigo N.; Rezende, Michelle Jakeline Cunha; Kartnaller, Vinicius; Carneiro, José Walkimar de M.; Stoyanov, Stanislav R.; Costa, Leonardo Moreira da

2018-04-01

The density functional theory is employed to determine the efficiency of 11 exchange-correlation (XC) functionals to compute the 1H and 13C NMR chemical shifts of p-tert-butylcalix[4]arene (ptcx4, R1 = C(CH3)3) and congeners using the 6-31G(d,p) basis set. The statistical analysis shows that B3LYP, B3PW91 and PBE1PBE are the best XC functionals for the calculation of 1H chemical shifts. Moreover, the best results for the 13C chemical shifts are obtained using the LC-WPBE, M06-2X and wB97X-D functionals. The performance of these XC functionals is tested for three other calix[4]arenes: p-sulfonic acid calix[4]arene (sfxcx4 - R1 = SO3H), p-nitro-calix[4]arene (ncx4, R1 = NO2) and calix[4]arene (cx4 - R1 = H). For 1H chemical shifts B3LYP, B3PW91 and PBE1PBE yield similar results, although B3PW91 shows more consistency in the calculated error for the different structures. For 13C NMR chemical shifts, the XC functional that stood out as best is LC-WPBE. Indeed, the three functionals selected for each of 1H and 13C show good accuracy and can be used in future studies involving the prediction of 1H and 13C chemical shifts for this type of compounds.

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

International Nuclear Information System (INIS)

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

1996-01-01

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

Characterizing crystal disorder of trospium chloride: a comprehensive, 13C CP/MAS NMR, DSC, FTIR, and XRPD study

Czech Academy of Sciences Publication Activity Database

Urbanová, Martina; Šturcová, Adriana; Brus, Jiří; Beneš, Hynek; Skořepová, E.; Kratochvíl, B.; Čejka, J.; Šeděnková, Ivana; Kobera, Libor; Policianová, Olivia; Šturc, A.

2013-01-01

Roč. 102, č. 4 (2013), s. 1235-1248 ISSN 0022-3549 R&D Projects: GA ČR GPP106/11/P426 Institutional support: RVO:61389013 Keywords : trospium chloride * solid state NMR * factor analysis Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.007, year: 2013

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

Science.gov (United States)

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

2005-07-18

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

Site-specific {sup 13}C content by quantitative isotopic {sup 13}C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

Energy Technology Data Exchange (ETDEWEB)

Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst [Firmenich SA, Corporate R and D Division, P.O. Box 239, 1211 Geneva 8 (Switzerland); Gilbert, Alexis; Yamada, Keita [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Yoshida, Naohiro [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Pagelot, Alain [Bruker Biospin SAS, 34 rue de l‘Industrie, 67166 Wissembourg Cedex (France); Moskau, Detlef; Moreno, Aitor [Bruker Biospin AG, Industriestrasse 26, 8117 Fällanden (Switzerland); Schleucher, Jürgen [Department of Medical Biochemistry and Biophysics, Umeå University, S-90187 Umeå (Sweden); Reniero, Fabiano; Holland, Margaret; Guillou, Claude [European Commission, Joint Research Centre – Institute for Health and Consumer Protection, via E. Fermi 2749, I-21027 Ispra (Italy); Silvestre, Virginie; Akoka, Serge [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Remaud, Gérald S., E-mail: gerald.remaud@univ-nantes.fr [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France)

2013-07-25

Graphical abstract: -- Highlights: •First ring test on isotopic {sup 13}C NMR spectrometry. •Evaluation of the intra- and inter-variability of the NMR spectrometers used. •Definition of a protocol for qualification of the performance of the spectrometer. -- Abstract: Isotopic {sup 13}C NMR spectrometry, which is able to measure intra-molecular {sup 13}C composition, is of emerging demand because of the new information provided by the {sup 13}C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic {sup 13}C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular {sup 13}C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic {sup 13}C NMR was then assessed on vanillin from three different origins associated with specific δ{sup 13}C{sub i} profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ{sup 13}C{sub i} in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

27Al MAS NMR spectroscopic identification of reaction intermediates in the carbothermal reduction and nitridation of alumina

International Nuclear Information System (INIS)

Jung, Woo-Sik; Chae, Seen-Ae

2010-01-01

The reaction intermediates in the carbothermal reduction and nitridation (CRN) reaction of γ-Al 2 O 3 were identified by 27 Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. This identification ruled out the possibility of a reaction mechanism involving the gaseous reaction intermediates. In the CRN reaction of γ-Al 2 O 3 , AlO 4 units were converted to AlN stepwise via AlN x O 4-x (x = 1, 2, 3) intermediates, while AlO 6 units were more slowly converted to AlN than AlO 4 units and the NMR peaks of partially nitridated AlO 6 units were not detected. The NMR peak intensities of partially nitridated AlO 4 units became weaker with increasing reaction temperature.

Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

Science.gov (United States)

Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

2010-01-01

We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

NMR studies of bent DNA using {sup 13}C-enriched samples

Energy Technology Data Exchange (ETDEWEB)

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

1994-12-01

Bending of the DNA double helix can be brought about by introducing runs of adenines (A-tracts) in phase with the helical repeat of the DNA. The requirements for bending of DNA by A-tracts are that the length of the A-tract be greater than 3 base pairs and that the A-tracts must be in phase with the helical repeat (every 10 or 11 bp). Other factors, such as the number of adenines in the run, flanking sequences, and whether the A-tracts are phased with respect to the 5{prime}A or the 3{prime}A, have effects upon the degree of bending as assayed by electrophoretic mobility on native polyacrylamide gels. There are a number of models for bending A-tract DNA. The junction-bending model postulates that the structure of A-tracts is similar to the fiber diffraction structure of poly A, in which there is a significant degree of base pair tilt with respect to the helix axis. In this model, bending occurs at the junction between the A-tract and the B-form helix to allow favorable stacking interactions to occur. The bend of the helix could arise as a result of some other perturbation of B-form DNA by A-tracts, such as propeller twist; bending also could be due to a combination of factors. Our goal is to find the structural features of A-tracts responsible for bending of the helix by performing NMR on oligonucleotides containing A-tracts to obtain higher resolution structural data. One of the problems encountered in NMR structure determination of nucleic acids and other macromolecules is the assignment of resonances to nuclei. This procedure can be greatly facilitated through the use of {sup 13}C-enriched nucleic acid samples. We are developing a technique for the enzymatic synthesis of labeled DNA for NMR. The technique we are developing is similar to RNA labeling techniques already in use. The technique involves growth of methylotrophic bacteria on {sup 13}CH{sub 3}OH.

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

Science.gov (United States)

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

2015-06-05

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

Carbon-13 composition of bulk dry wines by irm-EA/MS and irm-13C NMR: An indicator of vine water status

Directory of Open Access Journals (Sweden)

Guyon Francois

2017-01-01

Full Text Available Measurements performed on a set of 32 authentic wines (not submitted to any oenological treatment and their ethanol, recovered by distillation, show high correlation between δ13C of bulk wine and its ethanol. These measurements were performed by isotope ratio monitoring by mass spectrometry coupled to an elemental analyzer (irm-EA/MS. Then a series of wines produced by vines of which water status was assessed during the growing season with predawn leaf water potential measurements, was studied by irm-EA/MS. As expected δ13C is correlated to vine water status conditions, as a result of stomatal closure. The ethanol of these specific wines was also analyzed by isotope ratio monitoring and by nuclear magnetic resonance (irm-13C NMR to determine carbon-13 composition on the two specific sites of the ethanol skeleton. If these measurements confirm the correlation between 13C composition and vine growth conditions, the 13C stereospecific information does not make vine water status assessment more precise.

Evolution of organic matter during composting of different organic wastes assessed by CPMAS 13C NMR spectroscopy

International Nuclear Information System (INIS)

Caricasole, P.; Provenzano, M.R.; Hatcher, P.G.; Senesi, N.

2011-01-01

In this paper, the evolution of organic matter (OM) during composting of different mixtures of various organic wastes was assessed by means of chemical analyses and CPMAS 13 C NMR spectroscopy measured during composting. The trends of temperatures and C/N ratios supported the correct evolution of the processes. The CPMAS 13 C NMR spectra of all composting substrates indicated a reduction in carbohydrates and an increase in aromatic, phenolic, carboxylic and carbonylic C which suggested a preference by microorganisms for easily degradable C molecules. The presence of hardly degradable pine needles in one of the substrates accounted for the lowest increase in alkyl C and the lowest reduction in carbohydrates and carboxyl C as opposite to another substrate characterized by the presence of a highly degradable material such as spent yeast from beer production, which showed the highest increase of the alkyl C/O-alkyl C ratio. The highest increase of COOH deriving by the oxidative degradation of cellulose was shown by a substrate composed by about 50% of plant residues. The smallest increases in alkyl C/O-alkyl C ratio and in polysaccharides were associated to the degradation of proteins and lipids which are major components of sewage sludge. Results obtained were related to the different composition of fresh organic substrates and provided evidence of different OM evolution patterns as a function of the initial substrate composition.

Effect of pressure on the short-range structure and speciation of carbon in alkali silicate and aluminosilicate glasses and melts at high pressure up to 8 GPa: 13C, 27Al, 17O and 29Si solid-state NMR study

Science.gov (United States)

Kim, Eun Jeong; Fei, Yingwei; Lee, Sung Keun

2018-03-01

Despite the pioneering efforts to explore the nature of carbon in carbon-bearing silicate melts under compression, experimental data for the speciation and the solubility of carbon in silicate melts above 4 GPa have not been reported. Here, we explore the speciation of carbon and pressure-induced changes in network structures of carbon-bearing silicate (Na2O-3SiO2, NS3) and sodium aluminosilicate (NaAlSi3O8, albite) glasses quenched from melts at high pressure up to 8 GPa using multi-nuclear solid-state NMR. The 27Al triple quantum (3Q) MAS NMR spectra for carbon-bearing albite melts revealed the pressure-induced increase in the topological disorder around 4 coordinated Al ([4]Al) without forming [5,6]Al. These structural changes are similar to those in volatile-free albite melts at high pressure, indicating that the addition of CO2 in silicate melts may not induce any additional increase in the topological disorder around Al at high pressure. 13C MAS NMR spectra for carbon-bearing albite melts show multiple carbonate species, including [4]Si(CO3)[4]Si, [4]Si(CO3)[4]Al, [4]Al(CO3)[4]Al, and free CO32-. The fraction of [4]Si(CO3)[4]Al increases with increasing pressure, while those of other bridging carbonate species decrease, indicating that the addition of CO2 may enhance mixing of Si and Al at high pressure. A noticeable change is not observed for 29Si NMR spectra for the carbon-bearing albite glasses with varying pressure at 1.5-6 GPa. These NMR results confirm that the densification mechanisms established for fluid-free, polymerized aluminosilicate melts can be applied to the carbon-bearing albite melts at high pressure. In contrast, the 29Si MAS NMR spectra for partially depolymerized, carbon-bearing NS3 glasses show that the fraction of [5,6]Si increases with increasing pressure at the expense of Q3 species ([4]Si species with one non-bridging oxygen as the nearest neighbor). The pressure-induced increase in topological disorder around Si is evident from an

Other compounds isolated from Simira glaziovii and the 1H and 13C NMR chemical shift assignments of new 1-epi-castanopsol

International Nuclear Information System (INIS)

Araujo, Marcelo F. de; Vieira, Ivo J. Curcino; Braz-Filho, Raimundo; Carvalho, Mario G. de

2012-01-01

A new triterpene, 1-epi-castanopsol, besides eleven known compounds: sitosterol, stigmasterol, campesterol, lupeol, lupenone, simirane B, syringaresinol, scopoletin, isofraxidin, 6,7,8-trimethoxycoumarin and harman, were isolated from the wood of Simira glaziovii. The structures of the known compounds were defined by 1D, 2D 1 H, 13 C NMR spectra data analyses and comparison with literature data. The detailed spectral data analyses allowed the definition of the structure of the new 1-epi isomer of castanopsol and performance of 1 H and 13 C NMR chemical shift assignments. (author)

Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR

Science.gov (United States)

Yau, Wai-Ming; Thurber, Kent R.; Tycko, Robert

2014-07-01

We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25-30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2-6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92-128 for cross-polarized 13C NMR signals from 15N,13C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6-3.8 s for 1H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute 13C NMR signal amplitudes and build-up times, are approximately 2-4 times lower than with the best triradicals.

27Al Magic Angle Spinning–Nuclear Magnetic Resonance (MAS-NMR) Analyses Applied to Historical Mortars

Czech Academy of Sciences Publication Activity Database

Hanzlíček, Tomáš; Perná, Ivana; Brus, Jiří

2013-01-01

Roč. 7, č. 2 (2013), s. 153-164 ISSN 1558-3058 R&D Projects: GA AV ČR IAA300460702 Institutional research plan: CEZ:AV0Z30460519; CEZ:AV0Z40500505 Keywords : mortars * magic angle spinning –nuclear magnetic resonance (MAS-NMR) in solid state * alumina-silicates Subject RIV: DM - Solid Waste and Recycling Impact factor: 0.714, year: 2013 http://www.tandfonline.com/doi/abs/10.1080/15583058.2011.624253

Regioselectivity of tributyltin ether mediated alkylations. A 119Sn and 13C NMR study

International Nuclear Information System (INIS)

Cruzado, C.; Bernabe, M.; Martin-Lomas, M.

1989-01-01

The 119 Sn and 13 C NMR spectra of the stannylated species resulting from the treatment of conformationally rigid polyhydroxylated compounds with bis(tributyltin) oxide have been determined and the effect of N-methylimidazole, added as catalyst in tributyltin ether mediated regioselective alkylations, has been investigated. The observed signal intensity changes, upfield shifts, signal broadenings, and the results of variable temperature experiments have been interpreted as indicative of the selective formation of pentacoordinated tin species, involving conveniently disposed adjacent hydroxyl groups, on addition of the catalyst. On these bases, a mechanistic hypothesis for the observed regioselectivity of N-methylimidazole-catalyzed tributyltin ether mediated benzylations is proposed. 13 references, 5 tables

Changes in chemical composition of litter during decomposition: a review of published 13C NMR spectra

Czech Academy of Sciences Publication Activity Database

Cepáková, Šárka; Frouz, Jan

2015-01-01

Roč. 15, č. 3 (2015), s. 805-815 ISSN 0718-9516 Grant - others:GAJU(CZ) GAJU/04-146/2013P; GA ČR(CZ) GAP504/12/1288 Program:GA Institutional support: RVO:60077344 Keywords : 13C CPMAS NMR * litter decomposition * litter quality * soil organic matter Subject RIV: DF - Soil Science Impact factor: 1.600, year: 2015

New perspectives of 19F MAS NMR in the characterization of amorphous forms of atorvastatin in dosage formulations

Czech Academy of Sciences Publication Activity Database

Brus, Jiří; Urbanová, Martina; Šeděnková, Ivana; Brusová, H.

2011-01-01

Roč. 409, 1/2 (2011), s. 62-74 ISSN 0378-5173 R&D Projects: GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : 19F MAS NMR * factor analysis * polymorphism Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.350, year: 2011

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Prototropic tautomerism of 5-nitrobenzimidazole derivatives in {sup 1}H, {sup 13}C and {sup 15}N NMR spectra; Tautomeria prototropowa pochodnych 5-nitrobenzimidazolu w widmach {sup 1}H, {sup 13}C, {sup 15}N NMR

Energy Technology Data Exchange (ETDEWEB)

Wiench, J W; Bocian, W; Stefaniak, L [Inst. Chemii Organicznej, Polska Akademia Nauk, Warsaw (Poland)

1994-12-31

NMR spectra of 5-nitrobenzimidazole derivatives in DMSO solution show the fast exchange of protons. The line broadening in {sup 1}H,{sup 13}C and {sup 15}N spectra have been observed. The interpretation of the spectra has been done basing on chemical shifts values and couplings between nuclei in the investigated derivatives. 3 refs, 2 figs, 3 tabs.

Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses

International Nuclear Information System (INIS)

Eldridge, S.M.; Chen, C.R.; Xu, Z.H.; Nelson, P.N.; Boyd, S.E.; Meszaros, I.; Chan, K.Y.

2013-01-01

Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state 13 C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes

Synthesis of [5,6-13C2, 1-14C]olivetolic acid, methyl [1'-13C]olivetolate and [5,6-13C2, 1-14C]cannabigerolic acid

International Nuclear Information System (INIS)

Porwoll, J.P.; Leete, E.

1985-01-01

Potential advanced intermediates in the biosynthesis of delta 9 -tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous 13 C atoms and 14 C. Methyl [5,6- 13 C 2 , 1- 14 C]olivetolate was prepared from lithium [ 13 C 2 ]acetylide and dimethyl [2- 14 C]malonate. Reaction with geranyl bromide afforded methyl [5,6- 13 C 2 , 1- 14 C]cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The 13 C- 13 C couplings observable in the 13 C NMR spectra of these 13 C-enriched compounds and their synthetic precursors are recorded. Methyl [1'- 14 C]olivetolate was prepared from 13 CO 2 to confirm assignments of the 13 C chemical shifts in the pentyl side chain of these compounds. (author)

Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

Science.gov (United States)

Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

2016-01-21

Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

Intermolecular Interactions in Crystalline Theobromine as Reflected in Electron Deformation Density and (13)C NMR Chemical Shift Tensors.

Science.gov (United States)

Bouzková, Kateřina; Babinský, Martin; Novosadová, Lucie; Marek, Radek

2013-06-11

An understanding of the role of intermolecular interactions in crystal formation is essential to control the generation of diverse crystalline forms which is an important concern for pharmaceutical industry. Very recently, we reported a new approach to interpret the relationships between intermolecular hydrogen bonding, redistribution of electron density in the system, and NMR chemical shifts (Babinský et al. J. Phys. Chem. A, 2013, 117, 497). Here, we employ this approach to characterize a full set of crystal interactions in a sample of anhydrous theobromine as reflected in (13)C NMR chemical shift tensors (CSTs). The important intermolecular contacts are identified by comparing the DFT-calculated NMR CSTs for an isolated theobromine molecule and for clusters composed of several molecules as selected from the available X-ray diffraction data. Furthermore, electron deformation density (EDD) and shielding deformation density (SDD) in the proximity of the nuclei involved in the proposed interactions are calculated and visualized. In addition to the recently reported observations for hydrogen bonding, we focus here particularly on the stacking interactions. Although the principal relations between the EDD and CST for hydrogen bonding (HB) and stacking interactions are similar, the real-space consequences are rather different. Whereas the C-H···X hydrogen bonding influences predominantly and significantly the in-plane principal component of the (13)C CST perpendicular to the HB path and the C═O···H hydrogen bonding modulates both in-plane components of the carbonyl (13)C CST, the stacking modulates the out-of-plane electron density resulting in weak deshielding (2-8 ppm) of both in-plane principal components of the CST and weak shielding (∼ 5 ppm) of the out-of-plane component. The hydrogen-bonding and stacking interactions may add to or subtract from one another to produce total values observed experimentally. On the example of theobromine, we demonstrate

Advances in 27Al MAS NMR studies of geopolymers

Czech Academy of Sciences Publication Activity Database

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

2016-01-01

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

Mono terpenes characterization by {sup 1} H and {sup 13} C-1 NMR; Caracterizacao de monoterpenos por RMN - {sup 1} H e de {sup 13} C-1

Energy Technology Data Exchange (ETDEWEB)

Araujo, Martha T. de [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Fisico-Quimica; Silveira, Carmen L.P. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Quimica Organica; Mcchesney, James D [Mississippi Univ., University, MS (United States). Research Inst. of Pharmaceutical Sciences

1992-12-31

Artemisinine, a new lactone sesquiterpene containing one peroxide binding, is the main anti malarial agent obtained from the Artemisia annua L. Viewing to obtain a simple synthetic route for artemisinic acid preparation, which is the key intermediary for total synthesis of this type of anti malarial agent, R-carvone has been chosen as starting material. The S-carvone was used as model for reaction optimization and preparation of derivatives to be used for NMR studies. The main objective of this work is the signalling of the {sup 13} C and {sup 1} H NMR spectra, using the 2 D-COSY and 2 D-Hector spectra 4 refs., 3 figs., 1 tab

13C NMR and XPS characterization of anion adsorbent with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse

Science.gov (United States)

Cao, Wei; Wang, Zhenqian; Zeng, Qingling; Shen, Chunhua

2016-12-01

Despite amino groups modified crop straw has been intensively studied as new and low-cost adsorbent for removal of anionic species from water, there is still a lack of clear characterization for amino groups, especially quaternary ammonium groups in the surface of crop straw. In this study, we used 13C NMR and XPS technologies to characterize adsorbents with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse. 13C NMR spectra clearly showed the presence of quaternary ammonium groups in lignocelluloses structure of modified crop straw. The increase of nitrogen observed in XPS survey spectra also indicated the existence of quaternary ammonium group in the surface of the adsorbents. The curve fitting of high-resolution XPS N1s and C1s spectra were conducted to probe the composition of nitrogen and carbon contained groups, respectively. The results showed the proportion of quaternary ammonium group significantly increased in the prepared adsorbent's surface that was dominated by methyl/methylene, hydroxyl, quaternary ammonium, ether and carbonyl groups. This study proved that 13C NMR and XPS could be successfully utilized for characterization of quaternary ammonium modified crop straw adsorbents.

Determination of structural topology of a membrane protein in lipid bilayers using polarization optimized experiments (POE) for static and MAS solid state NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Mote, Kaustubh R. [University of Minnesota, Department of Chemistry (United States); Gopinath, T. [University of Minnesota, Department of Biochemistry, Molecular Biology and Biophysics (United States); Veglia, Gianluigi, E-mail: vegli001@umn.edu [University of Minnesota, Department of Chemistry (United States)

2013-10-15

The low sensitivity inherent to both the static and magic angle spinning techniques of solid-state NMR (ssNMR) spectroscopy has thus far limited the routine application of multidimensional experiments to determine the structure of membrane proteins in lipid bilayers. Here, we demonstrate the advantage of using a recently developed class of experiments, polarization optimized experiments, for both static and MAS spectroscopy to achieve higher sensitivity and substantial time-savings for 2D and 3D experiments. We used sarcolipin, a single pass membrane protein, reconstituted in oriented bicelles (for oriented ssNMR) and multilamellar vesicles (for MAS ssNMR) as a benchmark. The restraints derived by these experiments are then combined into a hybrid energy function to allow simultaneous determination of structure and topology. The resulting structural ensemble converged to a helical conformation with a backbone RMSD {approx}0.44 A, a tilt angle of 24 Degree-Sign {+-} 1 Degree-Sign , and an azimuthal angle of 55 Degree-Sign {+-} 6 Degree-Sign . This work represents a crucial first step toward obtaining high-resolution structures of large membrane proteins using combined multidimensional oriented solid-state NMR and magic angle spinning solid-state NMR.

Combined use of EPR and 23Na MAS NMR spectroscopy for assessing the properties of the mixed cobalt-nickel-manganese layers of P3-NayCo1-2xNixMnxO2.

Science.gov (United States)

Kalapsazova, M; Ivanova, S; Kukeva, R; Simova, S; Wegner, S; Zhecheva, E; Stoyanova, R

2017-10-11

Knowledge on the formation of mixed transition metal layers on lithium and sodium transition metal oxides, Li/Na(Co,Ni,Mn,)O 2 , determines the ability to control their electrochemical properties as electrode materials in alkaline ion batteries. Taking this into account, herein we combine the EPR and 23 Na MAS NMR spectroscopic techniques to gain insights into the structural peculiarities of the mixed cobalt-nickel-manganese layers of Na y Co 1-2x Ni x Mn x O 2 with a three-layer stacking (P3-type) structure. Two types of compositions are examined where diamagnetic Co 3+ and paramagnetic Ni 3+ and Mn 4+ are stabilized: Na 2/3 Co 1/3 Ni 1/3 Mn 1/3 O 2 and Na 1/2 Ni 1/2 Mn 1/2 O 2 . EPR spectroscopy operating in the X- and Q-band region is applied with an aim to improve the spectra resolution and, on the other hand, to provide straightforward information on the coordination of the transition metal ions inside the layers. The analysis of EPR spectra is based on the reference for the Mn 4+ and Ni 2+ ions occurring simultaneously in oxides with two layer stacking, P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 . Complementary to EPR, 23 Na MAS NMR spectroscopy at high spinning rates is undertaken to assess the local structure of the Na nucleus in the layered P3-Na y Co 1-2x Ni x Mn x O 2 oxides. All results are discussed taking into account the EPR and NMR data for the well-known lithium analogues O3-LiCo 1/3 Ni 1/3 Mn 1/3 O 2 and O3-LiNi 1/2 Mn 1/2 O 2 . Finally, the structure peculiarities of the transition metal layers extracted from the EPR and NMR methods are demonstrated by electrochemical intercalation of Li + ions into P3-Na y Co 1-2x Ni x Mn x O 2 .

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

Energy Technology Data Exchange (ETDEWEB)

Lippmaa, H.; Samoson, A.

1988-08-01

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

{sup 13}C NMR and XPS characterization of anion adsorbent with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse

Energy Technology Data Exchange (ETDEWEB)

Cao, Wei, E-mail: weicao@hqu.edu.cn; Wang, Zhenqian; Zeng, Qingling; Shen, Chunhua

2016-12-15

Highlights: • {sup 13}C NMR and XPS were successfully used to characterize quaternary ammonium groups in the surface of crop straw based anion adsorbents. • The results obtained from different kinds of crop straw material clearly confirmed the presence of quaternary ammonium groups. • The composition of C-groups and N-groups also were determined by curving fitting of high-resolution XPS C1 and N1 spectra. - Abstract: Despite amino groups modified crop straw has been intensively studied as new and low-cost adsorbent for removal of anionic species from water, there is still a lack of clear characterization for amino groups, especially quaternary ammonium groups in the surface of crop straw. In this study, we used {sup 13}C NMR and XPS technologies to characterize adsorbents with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse. {sup 13}C NMR spectra clearly showed the presence of quaternary ammonium groups in lignocelluloses structure of modified crop straw. The increase of nitrogen observed in XPS survey spectra also indicated the existence of quaternary ammonium group in the surface of the adsorbents. The curve fitting of high-resolution XPS N1s and C1s spectra were conducted to probe the composition of nitrogen and carbon contained groups, respectively. The results showed the proportion of quaternary ammonium group significantly increased in the prepared adsorbent’s surface that was dominated by methyl/methylene, hydroxyl, quaternary ammonium, ether and carbonyl groups. This study proved that {sup 13}C NMR and XPS could be successfully utilized for characterization of quaternary ammonium modified crop straw adsorbents.

Phosphole complexes of Gold(I) halides: Comparison of solution and solid-state structures by a combination of solution and CP/MAS 31P NMR spectroscopy and x-ray crystallography

International Nuclear Information System (INIS)

Attar, S.; Nelson, J.H.; Bearden, W.H.; Alcock, N.W.; Alyea, E.C.

1990-01-01

A series of complexes of 1-phenyldibenzophosphole (DBP), 1-phenyl-3,4,-dimethylphosphole (DMPP), and triphenylphosphine of the type L n AuX (n = 1, L = DBP, DMPP, Ph 3 P, X = Cl, Br, I; n = 3, L = DBP, X = Cl, Br, I; n = 3, L = Ph 3 P, X = Cl; n = 4, L = DBP, DMPP, X = PF 6 ) have been prepared and characterized. The structures of (DBP)AuCl (1), (DBP) 3 AuCl (2), and (DMPP)AuCl (3) have been determined from three-dimensional x-ray data collected by counter methods. Crystal structure of the complexes is reported. The CP/MAS 31 P( 1 H) NMR spectrum of complex 1 shows two resonances in a 1:1 intensity ratio, and the CP/MAS 31 P( 1 H) NMR spectrum of complex 3 shows three resonances in a 1:1:1 intensity ratio for reasons that are not yet understood. Though the three phospholes are crystallographically inequivalent (d(AuP) = 2.359 (1), 2.382 (1), and 2.374 (2) angstrom) the molecule has effective C s symmetry as evidenced by the observation of two 31 P resonances in a 2:1 intensity ratio in its CP/MAS 31 P( 1 H) NMR spectrum. Variable-temperature 31 P( 1 H) NMR spectra obtained on solutions of LAuCl + L in various ratios were analyzed to determine the nature of the species present in solution and to gain information regarding their relative stabilities as a function of the nature of the phosphine. 79 refs., 8 figs., 9 tabs

Synthesis of [21-13C]-cholesterol

International Nuclear Information System (INIS)

Caballero, G.M.; Gros, E.G.

1994-01-01

The synthesis of [21- 13 C]-cholesterol from 3β-O-(t-butyldimethylsilyl)-17β-cyano-androst-5-ene is described. Labelled carbon-atom was introduced by Grignard reaction of nitrile derivative with [ 13 C]-methylmagnesium iodide. Location of label was confirmed by 13 C-NMR spectroscopy. (author)

Structure and equilibria of Ca 2+-complexes of glucose and sorbitol from multinuclear ( 1H, 13C and 43Ca) NMR measurements supplemented with molecular modelling calculations

Science.gov (United States)

Pallagi, A.; Dudás, Cs.; Csendes, Z.; Forgó, P.; Pálinkó, I.; Sipos, P.

2011-05-01

Ca 2+-complexation of D-glucose and D-sorbitol have been investigated with the aid of multinuclear ( 1H, 13C and 43Ca) NMR spectroscopy and ab initio quantum chemical calculations. Formation constants of the forming 1:1 complexes have been estimated from one-dimensional 13C NMR spectra obtained at constant ionic strength (1 M NaCl). Binding sites were identified from 2D 1H- 43Ca NMR spectra. 2D NMR measurements and ab initio calculations indicated that Ca 2+ ions were bound in a tridentate manner via the glycosidic OH, the ethereal oxygen in the ring and the OH on the terminal carbon for the α- and β-anomers of glucose and for sorbitol simultaneous binding of four hydroxide moieties (C1, C2, C4 and C6) was suggested.

1H-13C NMR-based profiling of biotechnological starch utilization

DEFF Research Database (Denmark)

Sundekilde, Ulrik K.; Meier, Sebastian

2016-01-01

Starch is used in food-and non-food applications as a renewable and degradable source of carbon and energy. Insight into the chemical detail of starch degradation remains challenging as the starch constituents amylose and amylopectin are homopolymers. We show that considerable molecular detail...... of starch fragmentation can be obtained from multivariate analysis of spectral features in optimized 1H-13C NMR spectroscopy of starch fragments to identify relevant features that distinguish processes in starch utilization. As a case study, we compare the profiles of starch fragments in commercial beer...... samples. Spectroscopic profiles of homooligomeric starch fragments can be excellent indicators of process conditions. In addition, differences in the structure and composition of starch fragments have predictive value for down-stream process output such as ethanol production from starch. Thus, high...

13C NMR investigation of the structure of cationic carbonyls in transition metal zeolites

International Nuclear Information System (INIS)

Ben Taarit, Y.

1979-01-01

13 C NMR spectroscopy was used to investigate the nature of carbon monoxide adsorbed on transition metal ions hosted in a synthetic faujastite type zeolite. The adsorbed CO species was characterised by a highly shielded carbon nucleus. Using the Pople approximation for the paramagnetic shielding term, the observed chemical shift was rationalised assuming the formation of a cationic carbonyl species with an appreciable electronic transfer from the carbon lone pair to the transition metal ion and negligible π back-bonding if at all. (Auth.)

1H and 13C NMR spectral data of new saponins from Cordia piauhiensis.

Science.gov (United States)

Santos, Renata P; Silveira, Edilberto R; Uchôa, Daniel Esdras de A; Pessoa, Otília Deusdênia L; Viana, Francisco Arnaldo; Braz-Filho, Raimundo

2007-08-01

Two new bidesmoside triterpenoid saponins were isolated from stems of Cordia piauhiensis. Their structures, characterized as 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl pomolic acid 28-O-beta-D-glucopyranosyl ester (1) and 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (2), were unequivocally established after extensive NMR (1H, 13C, DEPT 135 degrees, COSY, HSQC, HMBC, TOCSY, and NOESY) studies. Copyright 2007 John Wiley & Sons, Ltd.

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.

Sup(13)C NMR studies of glucose disposal in normal and non-insulin-dependent diabetic humans

International Nuclear Information System (INIS)

Shulman, G.I.; Rothman, D.L.; Shulman, R.G.

1990-01-01

To examine the extent to which the defect in insulin action in subjects with non-insulin-dependent diabetes mellitus (NIDDM) can be accounted for by impairment of muscle glycogen synthesis, we performed combined hyperglycemic-hyperinsulinemic clamp studies with [ 13 C]glucose in five subjects with NIDDM and in six age- and weight-matched healthy subjects. The rate of incorporation of intravenously infused [1- 13 C]glucose into muscle glycogen was measured directly in the gastrocnemius muscle by means of a nuclear magnetic resonance (NMR) spectrometer with a 15.5 min time resolution and a 13 C surface coil. The steady-state plasma concentrations of insulin and glucose were similar in both study groups. The mean (±SE) rate of glycogen synthesis, as determined by 13 C NMR, was 78±28 and 183±39 μmol-glucosyl units (kg muscle tissue (wet mass)) -1 min -1 in the diabetic and normal subjects, respectively. The mean glucose uptake was markedly reduced in the diabetic as compared with the normal subjects. The mean rate of non-oxidative glucose metabolism was 22±4 μmol kg -1 min -1 in the diabetic subjects and 42±4 μmol kg -1 min -1 in the normal subjects. When these rates are extrapolated to apply to the whole body, the synthesis of muscle glycogen would account for most of the total-body glucose uptake and all of the non-oxidative glucose metabolism in both normal and diabetic subjects. We conclude that muscle glycogen synthesis is the principal pathway of glucose disposal in both normal and diabetic subjects and that defects in muscle glycogen synthesis have a dominant role in the insulin resistance that occurs in persons with NIDDM. (author)

Pressure-temperature phase diagram of a charge-ordered organic conductor studied by C13 NMR

Science.gov (United States)

Itou, T.; Miyagawa, K.; Nakamura, J.; Kanoda, K.; Hiraki, K.; Takahashi, T.

2014-07-01

We performed C13 NMR measurements on the quasi-one-dimensional (Q1D) charge-ordered system (DI-DCNQI)2Ag under ambient and applied pressure to clarify the pressure-temperature phase diagram. For pressures up to 15 kbar, the NMR spectra exhibit complicated splitting at low temperatures, indicating a "generalized 3D Wigner crystal" state. In this pressure region, we find that increased pressure causes a decrease in the charge disproportionation ratio, along with a decrease in the transition temperature of the generalized 3D Wigner crystal. In the high-pressure region, near 20 kbar, where a 1D confined liquid crosses over to a 3D Fermi liquid at high temperatures, the ground state is replaced by a nonmagnetic insulating state that is qualitatively different from the generalized 3D Wigner crystal.

Synergistic effect of the simultaneous chemometric analysis of {sup 1}H NMR spectroscopic and stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data: Application to wine analysis

Energy Technology Data Exchange (ETDEWEB)

Monakhova, Yulia B., E-mail: yul-monakhova@mail.ru [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Department of Chemistry, Saratov State University, Astrakhanskaya Street 83, Saratov 410012 (Russian Federation); Godelmann, Rolf [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Hermann, Armin [Landesuntersuchungsamt -Institut für Lebensmittelchemie und Arzneimittelprüfung, Emy-Roeder-Straße 1, Mainz 55129 (Germany); Kuballa, Thomas [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Cannet, Claire; Schäfer, Hartmut; Spraul, Manfred [Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Rutledge, Douglas N. [AgroParisTech, UMR 1145, Ingénierie Procédés Aliments, 16 rue Claude Bernard, Paris F-75005 (France)

2014-06-23

Highlights: • {sup 1}H NMR profilings of 718 wines were fused with stable isotope analysis data (SNIF-NMR, {sup 18}O, {sup 13}C). • The best improvement was obtained for prediction of the geographical origin of wine. • Certain enhancement was also obtained for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data). • Independent component analysis was used as an alternative chemometric tool for classification. - Abstract: It is known that {sup 1}H NMR spectroscopy represents a good tool for predicting the grape variety, the geographical origin, and the year of vintage of wine. In the present study we have shown that classification models can be improved when {sup 1}H NMR profiles are fused with stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data. Variable selection based on clustering of latent variables was performed on {sup 1}H NMR data. Afterwards, the combined data of 718 wine samples from Germany were analyzed using linear discriminant analysis (LDA), partial least squares-discriminant analysis (PLS-DA), factorial discriminant analysis (FDA) and independent components analysis (ICA). Moreover, several specialized multiblock methods (common components and specific weights analysis (ComDim), consensus PCA and consensus PLS-DA) were applied to the data. The best improvement in comparison with {sup 1}H NMR data was obtained for prediction of the geographical origin (up to 100% for the fused data, whereas stable isotope data resulted only in 60–70% correct prediction and {sup 1}H NMR data alone in 82–89% respectively). Certain enhancement was obtained also for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data), whereas in case of grape varieties improved models were not obtained. The combination of {sup 1}H NMR data with stable isotope data improves efficiency of classification models for geographical origin and vintage of wine and can be potentially used for other food products as well.

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

International Nuclear Information System (INIS)

Rusli bin Omar

1994-01-01

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

Evaluation of natural rubber from IAC series clones by solid state {sup 13}C NMR; Avaliacao da borracha natural de clones da serie IAC por {sup 13}C RMN no estado solido

Energy Technology Data Exchange (ETDEWEB)

Martins, Maria A.; Moreno, Rogerio M.B.; Goncalves, Paulo S. [Instituto Agronomico de Campinas, SP (Brazil). Centro de Cafe e Plantas Tropicais. Programa Seringueira]. E-mails: paulog@iac.sp.gov.br; mariaalice@cnpdia.embrapa.br; Forato, Lucimara A.; Colnago, Luiz A.; Mattoso, Luiz H.C. [EMBRAPA Instrumentacao Agropecuaria, Sao Carlos, SP (Brazil)]. E-mail: colnago@cnpdia.embrapa.br; forato@cnpdia.embrapa.br; rogerio@cnpdia.embrapa.br; mattoso@cnpdia.embrapa.br; Job, Aldo E. [Universidade Estadual Paulista (UNESP), Presidente Prudente, SP (Brazil). Departamento de Fisica, Quimica e Biologia

2005-07-01

Agronomic Institute (IAC) and EMBRAPA Agricultural Instrumentation (EMBRAPA/CNPDIA) have been studied Hevea species in order to increase the production of the natural rubber and to develop new clones more appropriated to Brazil's soil and climate. Structural characterization of natural rubber [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg.] from new clones of the IAC series (IAC 300, 301, 302, 303, 35, 40, and 56) and from RRIM 600 clone has been studied by high-resolution solid-state {sup 13}C NMR and by single pulse technique. The results have shown that the application of solid-state {sup 13}C NMR using the single pulse technique is a powerful tool to study natural rubber. The spectra obtained through this technique confirmed that natural rubber from all clones studied are cis-1,4-polyisoprene (author) form.(author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-05-08

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

Molecular composition of recycled organic wastes, as determined by solid-state {sup 13}C NMR and elemental analyses

Energy Technology Data Exchange (ETDEWEB)

Eldridge, S.M., E-mail: simon.eldridge@dpi.nsw.gov.au [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); NSW Department of Primary Industries, Bruxner Highway, Wollongbar, NSW 2477 (Australia); Chen, C.R. [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); Xu, Z.H. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Nelson, P.N. [School of Earth and Environmental Sciences, James Cook University, Cairns, QLD 4870 (Australia); Boyd, S.E. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Meszaros, I. [Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia); Chan, K.Y. [Graduate School of Environment, Macquarie University, North Ryde, NSW 2109 (Australia); Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia)

2013-11-15

Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state {sup 13}C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

Improved quantification of alite and belite in anhydrous Portland cements by 29Si MAS NMR: Effects of paramagnetic ions

DEFF Research Database (Denmark)

Poulsen, Søren Lundsted; Kocaba, Vanessa; Le Saoût, Gwenn

2009-01-01

The applicability, reliability, and repeatability of 29Si MAS NMR for determination of the quantities of alite (Ca3SiO5) and belite (Ca2SiO4) in anhydrous Portland cement was investigated in detail for 11 commercial Portland cements and the results compared with phase quantifications based...

1H NMR, 13C NMR and Computational Daft Study of the Solution Structure of 2-Formylcyclohexane-1,3-Dione and its Alkali Metal Salts

International Nuclear Information System (INIS)

Szczecinski, P.; Gryff-Keller, A.; Molchanov, S.

2005-01-01

Triketones have been known for many years to be efficient inhibitors of (4-hydroxyphenyl)pyruvate dioxygenase (HPPD), an enzyme very important for plants and animals, which catalyzes the tyrosine catabolism. Inhibition of this process has been used for both herbicidal and medical purposes. The mechanism of inhibition of HPPD by triketones is still under investigation. Recently, an almost complete mechanistic model of interaction between the mentioned enzyme and its inhibitor has been proposed. However, some arguments used by the authors to rationalize the proposed mechanism cannot be accepted. Therefore further developing of the investigation in this field is justified. In the present work the solution structure of 2-formylcyclohexane-1,3-dione, a simple molecular model of HPPD inhibitors, has been investigated using 1 H and 13 C NMR spectroscopic methods and theoretical DFT-based calculations. (author)

Iminium ion chemistry of mitosene DNA alkylating agents. Enriched 13C NMR and isolation studies.

Science.gov (United States)

Ouyang, A; Skibo, E B

2000-05-16

Described herein is a study of the reductive alkylation chemistry of mitosene antitumor agents. We employed a 13C-enriched electrophilic center to probe the fate of the iminium ion resulting from reductive activation. The 13C-labeled center permitted the identification of complex products resulting from alkylation reactions. In the case of DNA reductive alkylation, the type and number of alkylation sites were readily assessed by 13C NMR. Although there has been much excellent work done in the area of mitosene chemistry and biochemistry, the present study provides a number of new findings: (1) The major fate of the iminium ion is head-to-tail polymerization, even in dilute solutions. (2) Dithionite reductive activation results in the formation of mitosene sulfite esters as well as the previously observed sulfonate adducts. (3) The mitosene iminium ion alkylates the adenosine 6-amino group as well as the guanosine 2-amino group. The identification of the latter adduct was greatly facilitated by the 13C-label at the electrophilic center. (4) The mitosene iminium ion alkylates DNA at both nitrogen and oxygen centers without any apparent base selectivity. The complexity of mitosene reductive alkylation of DNA will require continued adduct isolation studies.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Science.gov (United States)

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

2002-01-01

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

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

DEFF Research Database (Denmark)

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

2008-01-01

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

Two-dimensional NMR spectroscopy of 13C methanol at less than 5 μT

Science.gov (United States)

Shim, Jeong Hyun; Lee, Seong-Joo; Hwang, Seong-min; Yu, Kwon-Kyu; Kim, Kiwoong

2014-09-01

Two-dimensional (2D) spectroscopy is one of the most significant applications of nuclear magnetic resonance (NMR). Here, we demonstrate that the 2D NMR can be performed even at a low magnetic field of less than 5 μT, which is ten times less than the Earth’s magnetic field. The pulses used in the experiment were composed of circularly polarized fields for coherent as well as wideband excitations. Since the excitation band covers the entire spectral range, the simplest two-pulse sequence delivered the full 2D spectrum. At 5 μT, methanol with 13C enriched up to 99% belongs to a strongly coupled regime, and thus its 2D spectrum exhibits complicated spectral correlations, which can be exploited as a fingerprint in chemical analysis. In addition, we show that, with compressive sensing, the acquisition of the 2D spectrum can be accelerated to take only 45% of the overall duration.

Two flavonoids from Iboza riparia and the unambiguous assignments of the 1H and 13C NMR signals of their methoxyle groups

International Nuclear Information System (INIS)

Haider, A.; Matida, A.; Zelnik, R.

1988-01-01

Two rare flavonoids, salvigenin and cirsimaritin, were isolated from the leaves of Iboza riparia. The 1 H and 13 C NMR spectra as well as non-quaternary carbon signals shift are analysed. (M.J.C.) [pt

An improved synthesis of α-13C glycine and heteronuclear NMR studies of its incorporation into thioredoxin

International Nuclear Information System (INIS)

Wishart, D.S.; Sykes, B.D.; Richards, F.M.

1992-01-01

We present an improved method to easily prepare gram quantities of α- 13 C glycine beginning from K 13 CN. The four step synthesis involves the production of an N, N-diphenyl-cyanoformamidine intermediate through the coupling of cyanide to N, N-diphenylcarbodiimide. Subsequent reduction by LiAlH 4 and hydrolysis of the resulting amidine produces fully enriched α- 13 C labelled glycine with a 45-50% yield. This relatively fast and simple synthesis uses only commonly available compounds and requires no special equipment, making the process easy to perform in any well equipped biochemistry laboratory. We further demonstrate that the product may be used, without extensive purification, to specifically label bacterially expressed proteins (E. coli thioredoxin) through standard biosynthetic procedures. We also show that the 13 C glycine-labelled protein may be readily analyzed using commonly available heteronuclear NMR techniques. Complete assignments for all 9 glycines of native E. coli thoredoxin are presented. (Author)

Characterization of organic matter in sediment cores of the Todos os Santos Bay, Bahia, Brazil, by elemental analysis and 13C NMR

International Nuclear Information System (INIS)

Costa, A.B.; Novotny, E.H.; Bloise, A.C.; Azevedo, E.R. de; Bonagamba, T.J.; Zucchi, M.R.; Santos, V.L.C.S.; Azevedo, A.E.G.

2011-01-01

Highlights: → The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by EA and 13 C NMR. → This article reports a study of six sediment cores collected at different depths and regions. → The elemental profiles of cores suggest an abrupt change in the sedimentation regime, corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects. → The results presented illustrate several important aspects of environmental impact of human activity on this bay. - Abstract: The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by elemental analysis and 13 C Nuclear Magnetic Resonance ( 13 C NMR). This article reports a study of six sediment cores collected at different depths and regions of Todos os Santos Bay. The elemental profiles of cores collected on the eastern side of Frades Island suggest an abrupt change in the sedimentation regime. Autoregressive Integrated Moving Average (ARIMA) analysis corroborates this result. The range of depths of the cores corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects in the region. Principal Component Analysis of the 13 C NMR spectra clearly differentiates sediment samples closer to the Subae estuary, which have high contents of terrestrial organic matter, from those closer to a local oil refinery. The results presented in this article illustrate several important aspects of environmental impact of human activity on this bay.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-04-01

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

Use of proton-enhanced, natural abundance /sup 13/C NMR to study the molecular dynamics of model and biological membranes

Energy Technology Data Exchange (ETDEWEB)

Cornell, B A [Commonwealth Scientific and Industrial Research Organization, North Ryde (Australia). Div. of Food Research; Keniry, M [Sydney Univ. (Australia). Dept. of Physical Chemistry; Hiller, R G [Macquarie Univ., North Ryde (Australia). School of Biological Sciences; Smith, R [La Trobe Univ., Bundoora (Australia). Dept. of Biochemistry

1980-06-16

Proton-enhanced NMR of the natural abundance /sup 13/C nuclei is used to study the lipid mobility in dispersions containing cholesterol, the polypeptide gramicidin A, and in membrane proparations derived from spinach chloroplasts and bovine brain myelin.

Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

NARCIS (Netherlands)

Negahdar, Leila; Gonzalez-Quiroga, Arturo; Otyuskaya, Daria; Toraman, Hilal E.; Liu, Li; Jastrzebski, Johann T B H; Van Geem, Kevin M.; Marin, Guy B.; Thybaut, Joris W.; Weckhuysen, Bert M.

2016-01-01

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas

Experimental solid state NMR of gas hydrates : problems and solutions

Energy Technology Data Exchange (ETDEWEB)

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

2008-07-01

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

Analysis of Hydroperoxides in solid Polyethylene by NMR and EPR Spectroscopy

International Nuclear Information System (INIS)

Assink, Roger A.; Celina, Mathias C.; Dunbar, Timothy D.; Alam, Todd M.; Clough, Roger Lee; Gillen, Kenneth T.

2000-01-01

The authors have shown that the hydroperoxide species in γ-irradiated 13 C-polyethylene can be directly observed by 13 C MAS NMR spectroscopy. The experiment was performed without the need for special sample preparation such as chemical derivatization or dissolution. Annealing experiments were employed to study the thermal decomposition of the hydroperoxide species and to measure an activation energy of 98 kJ/mol. EPR spectroscopy suggests that residual polyenyl and alkylperoxy radicals are predominantly trapped in interracial or crystalline regions, while the peroxy radicals observed after UV-photolysis of hydroperoxides are in amorphous regions

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

Directory of Open Access Journals (Sweden)

Ji-Hun An

2017-12-01

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

Other compounds isolated from Simira glaziovii and the {sup 1}H and {sup 13}C NMR chemical shift assignments of new 1-epi-castanopsol

Energy Technology Data Exchange (ETDEWEB)

Araujo, Marcelo F. de; Vieira, Ivo J. Curcino [Universidade Federal Rural do Rio de Janeiro, Seropedica, RJ (Brazil). Dept. de Quimica; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias Tecnologicas. Lab. de Ciencias Quimicas; Carvalho, Mario G. de, E-mail: mgeraldo@ufrrj.br [Universidade Federal do Rio de Janeiro (NPPN/UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisa em Produtos Naturais

2012-07-01

A new triterpene, 1-epi-castanopsol, besides eleven known compounds: sitosterol, stigmasterol, campesterol, lupeol, lupenone, simirane B, syringaresinol, scopoletin, isofraxidin, 6,7,8-trimethoxycoumarin and harman, were isolated from the wood of Simira glaziovii. The structures of the known compounds were defined by 1D, 2D {sup 1}H, {sup 13}C NMR spectra data analyses and comparison with literature data. The detailed spectral data analyses allowed the definition of the structure of the new 1-epi isomer of castanopsol and performance of {sup 1}H and {sup 13}C NMR chemical shift assignments. (author)

Lightweight hydrogen-storage material Mg0.65Sc0.35D2 studied with 2H and 2H–{45Sc} MAS NMR exchange spectroscopy

NARCIS (Netherlands)

Srinivasan, S.; Magusin, P.C.M.M.

2011-01-01

Using double-quantum 2H MAS NMR with 45Sc recoupling and Bloch–Siegert compensated 2H–{45Sc} TRAPDOR we have identified the overlapping NMR signals of deuterium with and without scandium neighbors in Mg0.65Sc0.35D2, a candidate lightweight material for hydrogen storage. At room temperature we also

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

International Nuclear Information System (INIS)

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

1991-01-01

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

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

Science.gov (United States)

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

2016-06-01

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

Spectroscopic effects in 1H and 13C NMR spectra of 4,4'-di-substituted 3,3'-diquinolines sulfides

International Nuclear Information System (INIS)

Pluta, K.

1994-01-01

The 1 H and 13 C NMR spectra of 4,4'-disubstituted sulfides of 3,3'-quinolines have been studied in CDCl 3 solutions. The observed spectroscopic effects have been interpreted in terms of molecule structure and configuration. The factors being responsible for the value of spectroscopic effects have been discussed

NMR structure analysis of uniformly 13C-labeled carbohydrates.

Science.gov (United States)

Fontana, Carolina; Kovacs, Helena; Widmalm, Göran

2014-06-01

In this study, a set of nuclear magnetic resonance experiments, some of them commonly used in the study of (13)C-labeled proteins and/or nucleic acids, is applied for the structure determination of uniformly (13)C-enriched carbohydrates. Two model substances were employed: one compound of low molecular weight [(UL-(13)C)-sucrose, 342 Da] and one compound of medium molecular weight ((13)C-enriched O-antigenic polysaccharide isolated from Escherichia coli O142, ~10 kDa). The first step in this approach involves the assignment of the carbon resonances in each monosaccharide spin system using the anomeric carbon signal as the starting point. The (13)C resonances are traced using (13)C-(13)C correlations from homonuclear experiments, such as (H)CC-CT-COSY, (H)CC-NOESY, CC-CT-TOCSY and/or virtually decoupled (H)CC-TOCSY. Based on the assignment of the (13)C resonances, the (1)H chemical shifts are derived in a straightforward manner using one-bond (1)H-(13)C correlations from heteronuclear experiments (HC-CT-HSQC). In order to avoid the (1) J CC splitting of the (13)C resonances and to improve the resolution, either constant-time (CT) in the indirect dimension or virtual decoupling in the direct dimension were used. The monosaccharide sequence and linkage positions in oligosaccharides were determined using either (13)C or (1)H detected experiments, namely CC-CT-COSY, band-selective (H)CC-TOCSY, HC-CT-HSQC-NOESY or long-range HC-CT-HSQC. However, due to the short T2 relaxation time associated with larger polysaccharides, the sequential information in the O-antigen polysaccharide from E. coli O142 could only be elucidated using the (1)H-detected experiments. Exchanging protons of hydroxyl groups and N-acetyl amides in the (13)C-enriched polysaccharide were assigned by using HC-H2BC spectra. The assignment of the N-acetyl groups with (15)N at natural abundance was completed by using HN-SOFAST-HMQC, HNCA, HNCO and (13)C-detected (H)CACO spectra.

Assessing Heterogeneity of Osteolytic Lesions in Multiple Myeloma by 1H HR-MAS NMR Metabolomics

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Laurette Tavel

2016-10-01

Full Text Available Multiple myeloma (MM is a malignancy of plasma cells characterized by multifocal osteolytic bone lesions. Macroscopic and genetic heterogeneity has been documented within MM lesions. Understanding the bases of such heterogeneity may unveil relevant features of MM pathobiology. To this aim, we deployed unbiased 1H high-resolution magic-angle spinning (HR-MAS nuclear magnetic resonance (NMR metabolomics to analyze multiple biopsy specimens of osteolytic lesions from one case of pathological fracture caused by MM. Multivariate analyses on normalized metabolite peak integrals allowed clusterization of samples in accordance with a posteriori histological findings. We investigated the relationship between morphological and NMR features by merging morphological data and metabolite profiling into a single correlation matrix. Data-merging addressed tissue heterogeneity, and greatly facilitated the mapping of lesions and nearby healthy tissues. Our proof-of-principle study reveals integrated metabolomics and histomorphology as a promising approach for the targeted study of osteolytic lesions.

A 13C-NMR study of mutant hemoglobins with altered oxygen affinity

International Nuclear Information System (INIS)

Smith, M.L.; Norden, B.; Edlund, U.; Paul, K.-G.

1986-01-01

The 13 CO-NMR spectra of carbonylhemoglobins Saint Mande (β 102Asn → Tyr), Malmo (β 97His → Gln), Hotel Dieu (β 99Asp → Gly) and A o have been determined. The positions of the 13 CO resonances for hemoglobins A o , Malmo and Hotel Dieu were similar indicating similar ligand environments for all. The 13 CO resonance for the β-subunit of Saint Mande was upfield-shifted compared to the others. This is evidence that structural changes at the β102 position directly affect iron-ligand bonding as well as quaternary structure. (Auth.)

1H and 13C NMR studies of palladium(2) and platinium(2) complexes with S-Methyl-L-Cysteine

International Nuclear Information System (INIS)

Allain, A.; Jezowska-Trzebiatowska, B.; Kozlowski, H.

1979-01-01

Our recent 1 H NMR studies on Pd(2)-S-Methyl-L-Cysteine(SMC) complexes have shown that the use of a conformational analysis to establish the complexed species existing in solution may provide clearer results than considering the proton chemical shift only. However, the use of the vicinal coupling constant of ABC spectrum of αCH-βCH 2 proton unit to estimate the rotational isomer fractions, may contain some ambiguity, especially on the proton assignment of the methylene group. For this reason 13 C NMR method has been applied to study these systems. (author)

C-13 NMR spectra of all-trans-N-retinylidene-n-butylamine as an analogue of the Schiff base linkage compound in visual pigment

Energy Technology Data Exchange (ETDEWEB)

Tokito, Y; Inoue, Y; Chujo, R [Tokyo Inst. of Tech. (Japan). Faculty of Science; Miyoshi, Y

1975-01-01

In the process of visual excitation, a visual pigment, rhodopsin, plays a role of a photoreceptor, and it has been known that the first step in the process is the photoisomerization of the rhodopsin visual chromophore. The bathochromic shift has been regarded as the result of the formation of Schiff base linkage of retinal with opsin. In this study, C-13 NMR spectra were obtained for the analogue of the compound with Schiff base linkage in the visual pigment, and the chemical shift change for going from all trans-retinal to all trans-N-retinylidene-n-butylamine (NRB) was discussed. Further, the effect of N protonation in NRB was examined as the reflection of the function of visual pigment. The compound with Schiff base linkage of all trans-retinal with n-butylamine, namely NRB, was used. The nuclear magnetic resonance (NMR) spectra of carbon-13 Fourier transformation were obtained for this sample at natural abundance with a JNM PS-100 spectrometer. In the C-13 FT NMR spectrum of NRB, besides eight peaks in the C-13 NMR of all trans-retinal, four peaks were observed in higher field region. They originated from the portion of n-butylamine in the compound with Schiff base linkage. The peaks in lower field region were assigned to eleven conjugated polyene carbons by the measurement of spin-lattice relaxation time and shift. The chemical shift change for going from retinal to NRB is shown. It is concluded that the ..pi..-electrons in polyene chains are considerably delocalized by the collapse of bond alteration in the retinal forming Schiff base linkage.

Characterization of two minor saponins from Cordia piauhiensis by 1H and 13C NMR spectroscopy.

Science.gov (United States)

Santos, Renata P; Silveira, Edilberto R; Lemos, Telma Leda G; Viana, Francisco Arnaldo; Braz-Filho, Raimundo; Pessoa, Otília Deusdênia L

2005-06-01

A careful NMR analysis with full assignment of the 1H and 13C spectral data for two minor saponins isolated from stems of Cordia piauhiensis is reported. These saponins were isolated by high-performance liquid chromatography and characterized as 3beta-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]pomolic acid 28-O-[beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl] ester (1) and 3beta-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]oleanolic acid 28-O-[beta-D-xylopyranosyl-(1 --> 2)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl] ester (2). Their structures were established using a combination of 1D and 2D (1H, 1H-COSY, TOCSY, NOESY, gs-HMQC and gs-HMBC) NMR techniques, electrospray ionization mass spectrometry and chemical evidence. Copyright 2005 John Wiley & Sons, Ltd.

13C, 15N Resonance Assignment of Parts of the HET-s Prion Protein in its Amyloid Form

International Nuclear Information System (INIS)

Siemer, Ansgar B.; Ritter, Christiane; Steinmetz, Michel O.; Ernst, Matthias; Riek, Roland; Meier, Beat H.

2006-01-01

The partial 15 N and 13 C solid-state NMR resonance assignment of the HET-s prion protein fragment 218-289 in its amyloid form is presented. It is based on experiments measured at MAS frequencies in the range of 20-40 kHz using exclusively adiabatic polarization-transfer schemes. The resonance assignment within each residue is based on two-dimensional 13 C-- 13 C correlation spectra utilizing the DREAM mixing scheme. The sequential linking of the assigned residues used a set of two- and three-dimensional 15 N-- 13 C correlation experiments. Almost all cross peaks visible in the spectra are assigned, but only resonances from 43 of the 78 amino-acid residues could be detected. The missing residues are thought to be highly disordered and/or highly dynamic giving rise to broad resonance lines that escaped detection in the experiments applied. The line widths of the observed resonances are narrow and comparable to line widths observed in micro-crystalline samples. The 43 assigned residues are located in two fragments of about 20 residues

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...

Evaluation of thermoplastic starch/MMT nanocomposites by nuclear magnetic resonance (NMR)

International Nuclear Information System (INIS)

Schlemmer, D.; Rodrigues, Tiago C.A.F.; Resck, I.S.; Sales, M.J.A.

2010-01-01

Starch has been studied for replace petrochemical plastics for short shelf life. However, the starch films have limitations: sensitivity to moisture and poor mechanical strength. This can be improved by incorporating loads such as montmorillonite, forming nanocomposites. Nanocomposites were prepared with 1, 3, 5 and 10% of montmorillonite, using vegetable oils of Brazilian Cerrado as plasticizers. The NMR spectra of oils are similar, but the intensities of the signals varying with the proportion of fatty acids. The molar mass of the oils was also calculated by NMR. The spectrum of CP/MAS 13 C NMR for starch presented a duplet in 97 and 98 ppm, on the amorphous domains of C-1, indicating a crystal type A. The spectra of the nanocomposites are similar to those of starch and oils. No new peaks appear, suggesting that there are no strong chemical bonds between components. (author)

Metabolic Effects of Hypoxia in Colorectal Cancer by 13C NMR Isotopomer Analysis

Directory of Open Access Journals (Sweden)

Ana M. Abrantes

2014-01-01

Full Text Available 13C NMR isotopomer analysis was used to characterize intermediary metabolism in three colorectal cancer cell lines (WiDr, LS1034, and C2BBe1 and determine the “metabolic remodeling” that occurs under hypoxia. Under normoxia, the three colorectal cancer cell lines present high rates of lactate production and can be seen as “Warburg” like cancer cells independently of substrate availability, since such profile was dominant at both high and low glucose media contents. The LS1034 was the less glycolytic of the three cell lines and was the most affected by the event of hypoxia, raising abruptly glucose consumption and lactate production. The other two colorectal cell lines, WiDr and C2BBe1, adapted better to hypoxia and were able to maintain their oxidative fluxes even at the very low levels of oxygen. These differential metabolic behaviors of the three colorectal cell lines show how important an adequate knowledge of the “metabolic remodeling” that follows a given cancer treatment is towards the correct (redesign of therapeutic strategies against cancer.

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 (PMLG5_m^$\\bar{x}$, PMLG5_mm^$\\bar{x}$x and SAM3) were analyzed to maximize the performance of through-bond transfer based

Acetate and bicarbonate assimilation and metabolite formation in Chlamydomonas reinhardtii: a 13C-NMR study.

Directory of Open Access Journals (Sweden)

Himanshu Singh

Full Text Available Cellular metabolite analyses by (13C-NMR showed that C. reinhardtii cells assimilate acetate at a faster rate in heterotrophy than in mixotrophy. While heterotrophic cells produced bicarbonate and CO2aq, mixotrophy cells produced bicarbonate alone as predominant metabolite. Experiments with singly (13C-labelled acetate ((13CH(3-COOH or CH(3-(13COOH supported that both the (13C nuclei give rise to bicarbonate and CO2(aq. The observed metabolite(s upon further incubation led to the production of starch and triacylglycerol (TAG in mixotrophy, whereas in heterotrophy the TAG production was minimal with substantial accumulation of glycerol and starch. Prolonged incubation up to eight days, without the addition of fresh acetate, led to an increased TAG production at the expense of bicarbonate, akin to that of nitrogen-starvation. However, such TAG production was substantially high in mixotrophy as compared to that in heterotrophy. Addition of mitochondrial un-coupler blocked the formation of bicarbonate and CO2(aq in heterotrophic cells, even though acetate uptake ensued. Addition of PSII-inhibitor to mixotrophic cells resulted in partial conversion of bicarbonate into CO2(aq, which were found to be in equilibrium. In an independent experiment, we have monitored assimilation of bicarbonate via photoautotrophy and found that the cells indeed produce starch and TAG at a much faster rate as compared to that in mixotrophy and heterotrophy. Further, we noticed that the accumulation of starch is relatively more as compared to TAG. Based on these observations, we suggest that acetate assimilation in C. reinhardtii does not directly lead to TAG formation but via bicarbonate/CO2(aq pathways. Photoautotrophic mode is found to be the best growth condition for the production of starch and TAG and starch in C. reinhardtii.

({sup 1} H, {sup 13} C and {sup 31} P) NMR of phosphonic acid derivatives; Ressonancia magnetica nuclear ({sup 1} H, {sup 13} C, {sup 31} P) de derivados do acido fosfonico

Energy Technology Data Exchange (ETDEWEB)

Campos, Valdevino; Costa, Valentim E. Uberti [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Quimica

1992-12-31

In the last years the development of phosphates analogues in the medical and agricultural pesticides has being very expressive. {sup 1} H, {sup 13} C and mainly {sup 31} P NMR are used for stereochemical and conformational analysis, and reactivity studies on the compounds resulting from those chemical processes 2 refs., 4 figs., 1 tab.

Soil nitrogen mineralisation and organic matter composition revealed by 13C NMR spectroscopy under repeated prescribed burning in eucalypt forests of south-east Queensland

International Nuclear Information System (INIS)

Guinto, D. F.; Saffigna, P. G.; Xu, Z. H.; House, A. P. N.; Perera, M. C. S.

1999-01-01

The effects of burning on in situ extractable nitrogen (NH + 4 -N+NO - 3 -N) and net N mineralisation following scheduled fuel reduction burns in repeatedly burnt dry and wet sclerophyll forest sites in south-east Queensland were assessed. In addition, soil organic matter composition in the wet sclerophyll site was assessed by 13 C NMR spectroscopy. The results showed that at the dry sclerophyll site, extractable N and net N mineralisation for 1 year were largely unaffected by burning, while at the wet sclerophyll site, these parameters decreased. 13 C NMR analysis of soil samples from the wet sclerophyll site revealed that there was a significant reduction in the proportion of O-alkyl (alkoxy/carbohydrate) C with increasing burning frequency. Statistically significant effects on the other chemical shift regions were not detected. The ratio of alkyl C to O-alkyl C, a proposed index of organic matter decomposition, increased with increasing burning frequency. A high ratio of alkyl C to O-alkyl C suggests low amounts of carbohydrates relative to waxes and cutins, which could in turn lead to slower mineralisation. The findings are in accord with this hypothesis. There were significant linear relationships between cumulative N mineralisation for 1 year and the proportions of alkyl C and O-alkyl C, and the ratio of alkyl C/O-alkyl C. Thus, in addition to reductions in substrate quantity (low organic C and total N for burnt soils), there was also an alteration of substrate quality as revealed by 13 C NMR spectroscopy which is reflected in low N mineralisation. Copyright (1999) CSIRO Publishing

Detection and assignment of phosphoserine and phosphothreonine residues by {sup 13}C-{sup 31}P spin-echo difference NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Lawrence P., E-mail: mcintosh@chem.ubc.ca; Kang, Hyun-Seo; Okon, Mark [University of British Columbia, Department of Biochemistry (Canada); Nelson, Mary L.; Graves, Barbara J. [University of Utah, Department of Oncological Sciences, Huntsman Cancer Institute (United States); Brutscher, Bernhard [CNRS, CEA, UJF, Institut de Biologie Structurale Jean-Pierre Ebel (France)], E-mail: bernhard.brutscher@ibs.fr

2009-01-15

A simple NMR method is presented for the identification and assignment of phosphorylated serine and threonine residues in {sup 13}C- or {sup 13}C/{sup 15}N-labeled proteins. By exploiting modest ({approx}5 Hz) 2- and 3-bond {sup 13}C-{sup 31}P scalar couplings, the aliphatic {sup 1}H-{sup 13}C signals from phosphoserines and phosphothreonines can be detected selectively in a {sup 31}P spin-echo difference constant time {sup 1}H-{sup 13}C HSQC spectrum. Inclusion of the same {sup 31}P spin-echo element within the {sup 13}C frequency editing period of an intraHNCA or HN(CO)CA experiment allows identification of the amide {sup 1}H{sup N} and {sup 15}N signals of residues (i) for which {sup 13}C{sup {alpha}}(i) or {sup 13}C{sup {alpha}}(i - 1), respectively, are coupled to a phosphate. Furthermore, {sup 31}P resonance assignments can be obtained by applying selective low power cw {sup 31}P decoupling during the spin-echo period. The approach is demonstrated using a PNT domain containing fragment of the transcription factor Ets-1, phosphorylated in vitro at Thr38 and Ser41 with the MAP kinase ERK2.

1H, 13C and 31P-NMR spectroscopic study of glucose metabolism of muscle larva Trichinella spiralis (U.S.A. strain), and the effects of the end-products on the host (mouse)

International Nuclear Information System (INIS)

Nishina, Masami

1988-01-01

1 H- and 13 C-nuclear magnetic resonance (NMR) spectroscopy was used to identify and quantitate metabolites excreted by muscle larva Trichinella spiralis maintained aerobically in the presence of D- ( 13 C 6 ) glucose and (1, 1'- 13 C 2 ) succinate. End-products of glucose metabolism studied by 1 H-NMR were lactate, acetate, succinate, proionate, n-valerate and alanine, at the molar ratio of 1:2:1:0.6:0.5:0.6. 13 C-NMR measurement proved that all the products originated from the glucose in the medium via the phosphoenolpyruvate carboxykinase-succinate pathway and the tricarboxylic acid cycle. In vivo 31 P-NMR spectra were also taken by the surface coil method from the leg muscle of mice which had been infected with T. spiralis. Intracelluar pH and relative amount of ATP in the leg muscle of the infected mice were found to decrease significantly as compared with that of control mice. (author)

Conditions to obtain precise and true measurements of the intramolecular {sup 13}C distribution in organic molecules by isotopic {sup 13}C nuclear magnetic resonance spectrometry

Energy Technology Data Exchange (ETDEWEB)

Bayle, Kevin [EBSI Team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 Rue de la Houssinière, BP 92208, F-44322, Nantes Cedex 3 (France); Gilbert, Alexis [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Earth–Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Julien, Maxime [EBSI Team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 Rue de la Houssinière, BP 92208, F-44322, Nantes Cedex 3 (France); Yamada, Keita [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Silvestre, Virginie; Robins, Richard J.; Akoka, Serge [EBSI Team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 Rue de la Houssinière, BP 92208, F-44322, Nantes Cedex 3 (France); Yoshida, Naohiro [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Earth–Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Remaud, Gérald S., E-mail: gerald.remaud@univ-nantes.fr [EBSI Team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 Rue de la Houssinière, BP 92208, F-44322, Nantes Cedex 3 (France)

2014-10-10

Highlights: • Evaluation of the trueness and precision criteria of isotopic {sup 13}C NMR spectrometry. • Use of bi-labelled [1,2-{sup 13}C{sub 2}]acetic acid to determine the performance of the instrumental response. • Inter-calibration of the {sup 13}C intramolecular composition of acetic acid using the technique GC-Py–irm-MS. - Abstract: Intramolecular {sup 13}C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic {sup 13}C NMR spectrometry provides a general tool for measuring the position-specific {sup 13}C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal {sup 13}C distribution, and (ii) an approach to determining the “absolute” position-specific {sup 13}C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the {sup 13}C frequency range of the studied molecule, i.e. the chemical shift range. The “absolute value” and, therefore, the trueness of the {sup 13}C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH{sub 3} by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py–irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py–irm-MS (thus, the “true” value) while the other showed a bias, which was

Synthesis of (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolic acid, methyl (1'-/sup 13/C)olivetolate and (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolic acid

Energy Technology Data Exchange (ETDEWEB)

Porwoll, J P; Leete, E [Minnesota Univ., Minneapolis (USA). Dept. of Chemistry

1985-03-01

Potential advanced intermediates in the biosynthesis of delta/sup 9/-tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous /sup 13/C atoms and /sup 14/C. Methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolate was prepared from lithium (/sup 13/C/sub 2/)acetylide and dimethyl (2-/sup 14/C)malonate. Reaction with geranyl bromide afforded methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The /sup 13/C-/sup 13/C couplings observable in the /sup 13/C NMR spectra of these /sup 13/C-enriched compounds and their synthetic precursors are recorded. Methyl (1'-/sup 14/C)olivetolate was prepared from /sup 13/CO/sub 2/ to confirm assignments of the /sup 13/C chemical shifts in the pentyl side chain of these compounds.

Recoupling and decoupling of nuclear spin interactions at high MAS frequencies: numerical design of CNnν symmetry-based RF pulse schemes

International Nuclear Information System (INIS)

Herbst, Christian; Herbst, Jirada; Kirschstein, Anika; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

2009-01-01

The CN n ν class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning solid state NMR studies of biological systems, involves the application of a basic 'C' element corresponding to an RF cycle with unity propagator. In this study, the design of CN n ν symmetry-based RF pulse sequences for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated 13 C- 13 C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated basic 'C' elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by an RF phase value. The phase-modulation profile of the 'C' element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were evaluated via numerical simulations and experimental measurements and are presented here

{sup 13}C-NMR studies on disulfide bond isomerization in bovine pancreatic trypsin inhibitor (BPTI)

Energy Technology Data Exchange (ETDEWEB)

Takeda, Mitsuhiro [Kumamoto University, Department of Structural BioImaging, Faculty of Life Sciences (Japan); Miyanoiri, Yohei [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Terauchi, Tsutomu [Tokyo Metropolitan University, Graduate School of Science and Engineering (Japan); Kainosho, Masatsune, E-mail: kainosho@tmu.ac.jp [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan)

2016-09-15

Conformational isomerization of disulfide bonds is associated with the dynamics and thus the functional aspects of proteins. However, our understanding of the isomerization is limited by experimental difficulties in probing it. We explored the disulfide conformational isomerization of the Cys14–Cys38 disulfide bond in bovine pancreatic trypsin inhibitor (BPTI), by performing an NMR line-shape analysis of its Cys carbon peaks. In this approach, 1D {sup 13}C spectra were recorded at small temperature intervals for BPTI samples selectively labeled with site-specifically {sup 13}C-enriched Cys, and the recorded peaks were displayed in the order of the temperature after the spectral scales were normalized to a carbon peak. Over the profile of the line-shape, exchange broadening that altered with temperature was manifested for the carbon peaks of Cys14 and Cys38. The Cys14–Cys38 disulfide bond reportedly exists in equilibrium between a high-populated (M) and two low-populated states (m{sub c14} and m{sub c38}). Consistent with the three-site exchange model, biphasic exchange broadening arising from the two processes was observed for the peak of the Cys14 α-carbon. As the exchange broadening is maximized when the exchange rate equals the chemical shift difference in Hz between equilibrating sites, semi-quantitative information that was useful for establishing conditions for {sup 13}C relaxation dispersion experiments was obtained through the carbon line-shape profile. With respect to the m{sub c38} isomerization, the {sup 1}H-{sup 13}C signals at the β-position of the minor state were resolved from the major peaks and detected by exchange experiments at a low temperature.

1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

International Nuclear Information System (INIS)

Arévalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernández-Maldonado, Arturo J.

2012-01-01

The location of extraframework cations in Sr 2+ and Ba 2+ ion-exchanged SAPO-34 was estimated by means of 1 H and 23 Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO 2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO 2 adsorption performance. Highlights: ► Location of extraframework Sr 2+ or Ba 2+ cations was estimated by means of 1 H and 23 Na MAS NMR. ► Level of Sr 2+ or Ba 2+ ion exchange was limited by the presence of protons and sodium cations. ► Presence of ammonium cations in the supercages facilitated the exchange. ► Sr 2+ and Ba 2+ ion exchanged SAPOs are outstanding CO 2 adsorbents.

Carbon-13 NMR study of switch variant anti-dansyl antibodies: Antigen binding and domain-domain interactions

International Nuclear Information System (INIS)

Kato, Koichi; Matsunaga, Chigusa; Odaka, Asano; Yamato, Sumie; Takaha, Wakana; Shimada, Ichio; Arata, Yoji

1991-01-01

A 13 C NMR study is reported of switch variant anti-dansyl antibodies, which possess the identical V H , V L , and C L domains in conjunction with highly homologous but not identical heavy-chain constant regions. Each of the antibodies has been selectively labeled with 13 C at the carbonyl carbon of Trp, Tyr, His, or Cys residue by growing hybridoma cells in serum-free medium. Spectral assignments have been made by folowing the procedure described previously for the switch variant antibodies labeled with [1- 13 C]Met. On the basis of the spectral data collected for the antibodies and their proteolytic fragments, the authors discuss how 13 C NMR spectroscopy can be used for the structural analyses of antigen binding and also of domain-domain interactions in the antibody molecule

Application of DRIFTS, ¹³ C NMR, and py-MBMS to Characterize the Effects of Soil Science Oxidation Assays on Soil Organic Matter Composition in a Mollic Xerofluvent

Energy Technology Data Exchange (ETDEWEB)

Margenot, Andrew J.; Calderón, Francisco J.; Magrini, Kimberly A.; Evans, Robert J.

2016-12-20

Chemical oxidations are routinely employed in soil science to study soil organic matter (SOM), and their interpretation could be improved by characterizing oxidation effects on SOM composition with spectroscopy. We investigated the effects of routinely employed oxidants on SOM composition in a Mollic Xerofluvent representative of intensively managed agricultural soils in the California Central Valley. Soil samples were subjected to oxidation by potassium permanganate (KMnO4), sodium hypochlorite (NaOCl), and hydrogen peroxide (H2O2). Additionally, non-oxidized and oxidized soils were treated with hydrofluoric acid (HF) to evaluate reduction of the mineral component to improve spectroscopy of oxidation effects. Oxidized non-HF and HF-treated soils were characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), 13C cross polarization magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy, and pyrolysis molecular beam mass spectrometry (py-MBMS), and for particle size distribution (PSD) using laser diffractometry (LD). Across the range of soil organic carbon (OC) removed by oxidations (14-72%), aliphatic C-H stretch at 3000-2800 cm-1 (DRIFTS) decreased with OC removal, and this trend was enhanced by HF treatment due to significant demineralization in this soil (70%). Analysis by NMR spectroscopy was feasible only after HF treatment, and did not reveal trends between OC removal and C functional groups. Pyrolysis-MBMS did not detect differences among oxidations, even after HF treatment of soils. Hydrofluoric acid entailed OC loss (13-39%), and for H2O2 oxidized soils increased C:N and substantially decreased mean particle size. This study demonstrates the feasibility of using HF to improve characterizations of SOM composition following oxidations as practiced in soil science, in particular for DRIFTS. Since OC removal by oxidants, mineral removal by HF, and the interaction of oxidants and HF observed for this soil may

1H, 13C and 13N chemical shifts and 1H-15N and 13C-15N heteronuclear spin-spin coupling constants n the NMR spectra of 5-substituted furfural oximes

International Nuclear Information System (INIS)

Popelis, Yu.Yu.; Liepin'sh, E.E.; Lukevits, E.Ya.

1986-01-01

The 1 H, 13 C, and 15 N NMR spectra of 15 N-enriched 5-substituted furfural oximes were investigated. It was shown that the chemical shifts of the ring atoms and the oxime group correlate satisfactorily with the F and R substituent constants, whereas their sensitivity to the effect of the substituents is lower than in monosubstituted furan derivatives. The constants of spin-spin coupling between the ring protons and the oxime group were determined. An analysis of the 1 H- 1 H spin-spin coupling constants (SSCC) on the basis of their stereospecificity indicates that the E isomers have primarily an s-trans conformation in polar dimethyl sulfoxide, whereas the Z isomers, on the other hand, have an s-cis conformation. The signs of the direct and geminal 13 C- 15 N SSCC were determined for 5-trimethylsilylfurfural oxime

Selective {sup 2}H and {sup 13}C labeling in NMR analysis of solution protein structure and dynamics

Energy Technology Data Exchange (ETDEWEB)

LeMaster, D.M. [Northwestern Univ., Evanston, IL (United States)

1994-12-01

Preparation of samples bearing combined isotope enrichment patterns has played a central role in the recent advances in NMR analysis of proteins in solution. In particular, uniform {sup 13}C, {sup 15}N enrichment has made it possible to apply heteronuclear multidimensional correlation experiments for the mainchain assignments of proteins larger than 30 KDa. In contrast, selective labeling approaches can offer advantages in terms of the directedness of the information provided, such as chirality and residue type assignments, as well as through enhancements in resolution and sensitivity that result from editing the spectral complexity, the relaxation pathways and the scalar coupling networks. In addition, the combination of selective {sup 13}C and {sup 2}H enrichment can greatly facilitate the determination of heteronuclear relaxation behavior.

A MAS NMR and DRIFT study of the Ga species in Ga/H-ZSM5 catalysts and their effect on propane ammoxidation

NARCIS (Netherlands)

Pal, P.; Quartararo, J.; Hamid, abd S.B.; Derouane, E.G.; Védrine, J.C.; Magusin, P.C.M.M.; Anderson, B.G.

2005-01-01

71Ga, 27Al and 29Si MAS-NMR and DRIFT spectroscopies were used to characterize the state of gallium in Ga/H-ZSM5 catalysts tested for their ability to catalyse the ammoxidation of propane. Ga-species were observed in two different possible environments: octahedrally-coordinated gallium in small

{sup 13}C, {sup 15}N Resonance Assignment of Parts of the HET-s Prion Protein in its Amyloid Form

Energy Technology Data Exchange (ETDEWEB)

Siemer, Ansgar B. [Physical Chemistry (Switzerland); Ritter, Christiane [Salk Institute, Structural Biology Laboratory (United States); Steinmetz, Michel O. [Paul Scherrer Institut, Biomolecular Research, Structural Biology (Switzerland); Ernst, Matthias [Physical Chemistry (Switzerland); Riek, Roland [Salk Institute, Structural Biology Laboratory (United States); Meier, Beat H. [Physical Chemistry (Switzerland)

2006-02-15

The partial {sup 15}N and {sup 13}C solid-state NMR resonance assignment of the HET-s prion protein fragment 218-289 in its amyloid form is presented. It is based on experiments measured at MAS frequencies in the range of 20-40 kHz using exclusively adiabatic polarization-transfer schemes. The resonance assignment within each residue is based on two-dimensional {sup 13}C--{sup 13}C correlation spectra utilizing the DREAM mixing scheme. The sequential linking of the assigned residues used a set of two- and three-dimensional {sup 15}N--{sup 13}C correlation experiments. Almost all cross peaks visible in the spectra are assigned, but only resonances from 43 of the 78 amino-acid residues could be detected. The missing residues are thought to be highly disordered and/or highly dynamic giving rise to broad resonance lines that escaped detection in the experiments applied. The line widths of the observed resonances are narrow and comparable to line widths observed in micro-crystalline samples. The 43 assigned residues are located in two fragments of about 20 residues.

/sup 13/C, /sup 17/O, and /sup 33/S NMR spectra of alkyl phenyl sulfones C/sub 6/H/sub 5/SO/sub 2/Alk

Energy Technology Data Exchange (ETDEWEB)

Bzhezovskii, V.M.; Valeev, R.B.; Kalabin, G.A.; Aliev, I.A.

1987-06-20

The /sup 13/C, /sup 17/O, and /sup 33/S NMR spectra of alkyl phenyl sulfones C/sub 6/H/sub 5/SO/sub 2/Alk were obtained. The changes in the screening of the /sup 13/C, /sup 17/O, and /sup 33/S nuclei in these compounds are determined by the effect of the alkyl substituents, which alternates in sign and decreases along the chain of atoms in the order: CH/sub 3/, C/sub 2/H/sub 5/, iso-C/sub 3/H/sub 7/, and tert-C/sub 4/H/sub 9/. In the alkyl phenyl sulfides C/sub 6/H/sub 5/SAlk the additional effect of disruption in the p,..pi.. interaction between the sulfur atom and the benzene ring as a result of conformational changes is superimposed on the screening of the /sup 13/C/sup ortho/ nuclei. For the changes in the screening of the /sup 13/C/sup para/ nuclei in C/sub 6/H/sub 5/SAlk the steric disruption of the p,..pi.. conjugation by the alkyl substituents is determining.

Synthesis of (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolic acid, methyl (1'-/sup 13/C)olivetolate and (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolic acid

Energy Technology Data Exchange (ETDEWEB)

Porwoll, J.P.; Leete, E. (Minnesota Univ., Minneapolis (USA). Dept. of Chemistry)

1985-03-01

Potential advanced intermediates in the biosynthesis of delta/sup 9/-tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous /sup 13/C atoms and /sup 14/C. Methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolate was prepared from lithium (/sup 13/C/sub 2/)acetylide and dimethyl (2-/sup 14/C)malonate. Reaction with geranyl bromide afforded methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The /sup 13/C-/sup 13/C couplings observable in the /sup 13/C NMR spectra of these /sup 13/C-enriched compounds and their synthetic precursors are recorded. Methyl (1'-/sup 14/C)olivetolate was prepared from /sup 13/CO/sub 2/ to confirm assignments of the /sup 13/C chemical shifts in the pentyl side chain of these compounds.

Organic matter characterization during the anaerobic digestion of different biomasses by means of CPMAS 13C NMR spectroscopy

International Nuclear Information System (INIS)

Tambone, Fulvia; Adani, Fabrizio; Gigliotti, Giovanni; Volpe, Daniela; Fabbri, Claudio; Provenzano, Maria Rosaria

2013-01-01

The aim of this work was to characterize ingestates and their corresponding digestates obtained in two full-scale biogas production plants processing a) mixtures of organic wastes in co-digestion, and b) pig slurry in order to assess the organic matter transformation during anaerobic digestion by means of chemical analysis and 13 CPMAS-NMR spectroscopy. Results proved that digestates obtained by different organic substrates exhibited significant chemical differences related to the different initial composition of substrates. We proposed the use of the aliphaticity index in order to highlight the different chemical nature of ingestates and their corresponding digestates. In order to verify whether the AD process leads to stabilized final products regardless the initial composition of biomass in view of a possible agronomical use of digestate, a comparison of CPMAS 13 C NMR data of a number of ingestates and digestates available in literature was carried out. Results indicated that most of the aromatic structures present in the substrate tend to degrade during the process and that anaerobic digestion proceeds through preferential degradation of carbohydrates such as cellulose and hemicellulose and, as a consequence, concentration of more chemically recalcitrant aliphatic molecules occurs. -- Highlights: ► We studied anaerobic digestion by means of chemical analysis and 13 CPMAS-NMR spectroscopy. ► Significant chemical differences in digestates were highlighted. ► We proposed the use of the aliphaticity index in order to differentiate digestates. ► Most of the aromatic structures tend to degrade. ► Carbohydrates are degraded and recalcitrant aliphatic molecules concentrate

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

DEFF Research Database (Denmark)

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

1997-01-01

29Si magic-angle spinning (MAS) NMR spectroscopy is shown to be a valuable tool for obtaining the quantities of alite and belite in hydrated Portland cements. The hydration (1-180 days) of a white Portland cement with 10 wt.% silica fume added is investigated and the degrees of hydration for alite...

Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K.

Science.gov (United States)

Thurber, Kent R; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

2013-01-01

We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20-25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier, but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized (13)C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional (13)C MAS NMR spectra of frozen solutions of uniformly (13)C-labeled l-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly (13)C-labeled amino acids. Published by Elsevier Inc.

Carbon-13 NMR study of switch variant anti-dansyl antibodies: Antigen binding and domain-domain interactions

Energy Technology Data Exchange (ETDEWEB)

Kato, Koichi; Matsunaga, Chigusa; Odaka, Asano; Yamato, Sumie; Takaha, Wakana; Shimada, Ichio; Arata, Yoji (Univ. of Tokyo (Japan))

1991-07-02

A {sup 13}C NMR study is reported of switch variant anti-dansyl antibodies, which possess the identical V{sub H}, V{sub L}, and C{sub L} domains in conjunction with highly homologous but not identical heavy-chain constant regions. Each of the antibodies has been selectively labeled with {sup 13}C at the carbonyl carbon of Trp, Tyr, His, or Cys residue by growing hybridoma cells in serum-free medium. Spectral assignments have been made by folowing the procedure described previously for the switch variant antibodies labeled with (1-{sup 13}C)Met. On the basis of the spectral data collected for the antibodies and their proteolytic fragments, the authors discuss how {sup 13}C NMR spectroscopy can be used for the structural analyses of antigen binding and also of domain-domain interactions in the antibody molecule.

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

DEFF Research Database (Denmark)

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

2016-01-01

Para-amino salicylate (PAS), a tubercolosis drug, was intercalated in three different layered double hydroxides (MgAl, ZnAl, and CaAl-LDH) and the samples were studied by multi-nuclear (1H, 13C, and 27Al) solid state NMR (SSNMR) spectroscopy in combination with powder X-ray diffraction (PXRD....... Moreover, 13C MAS NMR and infra-red spectroscopy show that PAS did not decompose during synthesis. Large amounts (20-41%) of amorphous aluminum impurities were detected in the structure using 27Al single pulse and 3QMAS NMR spectra, which in combination with 1H single and double quantum experiments also...... showed that the M(II):Al ratio was higher than predicted from the bulk metal composition of MgAl-PAS and ZnAl-PAS. Moreover, the first high-resolution 1H SSNMR spectra of a CaAl LDH is reported and assigned using 1H single and double quantum experiments in combination with 27Al{1H} HETCOR....

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

Science.gov (United States)

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

2018-02-14

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

[1-13C]Glucose entry in neuronal and astrocytic intermediary metabolism of aged rats. A study of the effects of nicergoline treatment by 13C NMR spectroscopy.

Science.gov (United States)

Miccheli, Alfredo; Puccetti, Caterina; Capuani, Giorgio; Di Cocco, Maria Enrica; Giardino, Luciana; Calzà, Laura; Battaglia, Angelo; Battistin, Leontino; Conti, Filippo

2003-03-14

Age-related changes in glucose utilization through the TCA cycle were studied using [1-13C]glucose and 13C, 1H NMR spectroscopy on rat brain extracts. Significant increases in lactate levels, as well as in creatine/phosphocreatine ratios (Cr/PCr), and a decrease in N-acetyl-aspartate (NAA) and aspartate levels were observed in aged rat brains as compared to adult animals following glucose administration. The total amount of 13C from [1-13C]glucose incorporated in glutamate, glutamine, aspartate and GABA was significantly decreased in control aged rat brains as compared to adult brains. The results showed a decrease in oxidative glucose utilization of control aged rat brains. The long-term nicergoline treatment increased NAA and glutamate levels, and decreased the lactate levels as well as the Cr/PCr ratios in aged rat brains as compared to adult rats. The total amount of 13C incorporated in glutamate, glutamine, aspartate, NAA and GABA was increased by nicergoline treatment, showing an improvement in oxidative glucose metabolism in aged brains. A significant increase in pyruvate carboxylase/pyruvate dehydrogenase activity (PC/PDH) in the synthesis of glutamate in nicergoline-treated aged rats is consistent with an increase in the transport of glutamine from glia to neurons for conversion into glutamate. In adult rat brains, no effect of nicergoline on glutamate PC/PDH activity was observed, although an increase in PC/PDH activity in glutamine was, suggesting that nicergoline affects the glutamate/glutamine cycle between neurons and glia in different ways depending on the age of animals. These results provide new insights into the effects of nicergoline on the CNS.

Biosynthesis of quinolizidine alkaloids. Incorporation of [1-amino-15N, 1-13C] cadaverine into lupanine, 13-hydroxylupanine, and angustifoline

International Nuclear Information System (INIS)

Rana, J.; Robins, D.J.

1985-01-01

The labelling patterns in (+)-lupanine, (+)-13-hydroxylupanine, and (+)-angustifoline derived biosynthetically from [1-amino- 15 N,1- 13 C]-1,5-diaminopentane (cadaverine) have been established by 13 C n.m.r. spectroscopy. Three cadaverine units are incorporated to about the same extent into each of these three alkaloids. The presence of two doublets due to 13 C- 15 N coupling in the 13 C brace 1 H brace n.m.r. spectra associated with C-2 and C-15 of lupanine and 13-hydroxylupanine, and one 13 C- 15 N doublet at C-2 of angustifoline, indicate that two of the cadaverine units are converted into the outer rings of the tetracyclic quinolizidine alkaloids in a specific fashion. (author)

General method of preparation of uniformly 13C, 15N-labeled DNA fragments for NMR analysis of DNA structures

International Nuclear Information System (INIS)

Rene, Brigitte; Masliah, Gregoire; Zargarian, Loussine; Mauffret, Olivier; Fermandjian, Serge

2006-01-01

Summary 13 C, 15 N labeling of biomolecules allows easier assignments of NMR resonances and provides a larger number of NMR parameters, which greatly improves the quality of DNA structures. However, there is no general DNA-labeling procedure, like those employed for proteins and RNAs. Here, we describe a general and widely applicable approach designed for preparation of isotopically labeled DNA fragments that can be used for NMR studies. The procedure is based on the PCR amplification of oligonucleotides in the presence of labeled deoxynucleotides triphosphates. It allows great flexibility thanks to insertion of a short DNA sequence (linker) between two repeats of DNA sequence to study. Size and sequence of the linker are designed as to create restriction sites at the junctions with DNA of interest. DNA duplex with desired sequence and size is released upon enzymatic digestion of the PCR product. The suitability of the procedure is validated through the preparation of two biological relevant DNA fragments

Assessing the extent of decomposition of natural organic materials using solid-state 13C NMR spectroscopy

International Nuclear Information System (INIS)

Baddock, J.A.; Oades, J.M.; Nelson, P.N.; Skene, T.M.; Golchin, A.; Clarke, P.

1997-01-01

Solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy has become an important tool for examining the chemical structure of natural organic materials and the chemical changes associated with decomposition. In this paper, solid-state 13 C NMR data pertaining to changes in the chemical composition of a diverse range of natural organic materials, including wood, peat, composts, forest litter layers, and organic materials in surface layers of mineral soils, were reviewed with the objective of deriving an index of the extent of decomposition of such organic materials based on changes in chemical composition. Chemical changes associated with the decomposition of wood varied considerably and were dependent on a strong interaction between the species of wood examined and the species composition of the microbial decomposer community, making the derivation of a single general index applicable to wood decomposition unlikely. For the remaining forms of natural organic residues, decomposition was almost always associated with an increased content of alkyl C and a decreased content of O-alkyl C. The concomitant increase and decrease in alkyl and O-alkyl C contents, respectively, suggested that the ratio of alkyl to O-alkyl carbon (A/O-A ratio) may provide a sensitive index of the extent of decomposition. Contrary to the traditional view that humic substances with an aromatic core accumulate as decomposition proceeds, changes in the aromatic region were variable and suggested a relationship with the activity of lignin-degrading fungi. The A/O-A ratio did appear to provide a sensitive index of extent of decomposition provided that its use was restricted to situations where the organic materials were derived from a common starting material. In addition, the potential for adsorption of highly decomposable materials on mineral soil surfaces and the impacts which such an adsorption may have on bioavailability required consideration when the A/O-A ratio was used to assess the

Analysis of neuron–astrocyte metabolic cooperation in the brain of db/db mice with cognitive decline using 13C NMR spectroscopy

Science.gov (United States)

Zheng, Hong; Zheng, Yongquan; Wang, Dan; Cai, Aimin; Lin, Qiuting; Zhao, Liangcai; Chen, Minjiang; Deng, Mingjie; Ye, Xinjian

2016-01-01

Type 2 diabetes has been linked to cognitive impairment, but its potential metabolic mechanism is still unclear. The present study aimed to explore neuron–astrocyte metabolic cooperation in the brain of diabetic (db/db, BKS.Cg-m+/+ Leprdb/J) mice with cognitive decline using 13C NMR technique in combination with intravenous [2-13C]-acetate and [3-13C]-lactate infusions. We found that the 13C-enrichment from [2-13C]-acetate into tricarboxylic acid cycle intermediate, succinate, was significantly decreased in db/db mice with cognitive decline compared with wild-type (WT, C57BLKS/J) mice, while an opposite result was obtained after [3-13C]-lactate infusion. Relative to WT mice, db/db mice with cognitive decline had significantly lower 13C labeling percentages in neurotransmitters including glutamine, glutamate, and γ-aminobutyric acid after [2-13C]-acetate infusion. However, [3-13C]-lactate resulted in increased 13C-enrichments in neurotransmitters in db/db mice with cognitive decline. This may indicate that the disturbance of neurotransmitter metabolism occurred during the development of cognitive decline. In addition, a reduction in 13C-labeling of lactate and an increase in gluconeogenesis were found from both labeled infusions in db/db mice with cognitive decline. Therefore, our results suggest that the development of cognitive decline in type 2 diabetes may be implicated to an unbalanced metabolism in neuron–astrocyte cooperation and an enhancement of gluconeogenesis. PMID:26762505

Analysis of neuron-astrocyte metabolic cooperation in the brain of db/db mice with cognitive decline using 13C NMR spectroscopy.

Science.gov (United States)

Zheng, Hong; Zheng, Yongquan; Wang, Dan; Cai, Aimin; Lin, Qiuting; Zhao, Liangcai; Chen, Minjiang; Deng, Mingjie; Ye, Xinjian; Gao, Hongchang

2017-01-01

Type 2 diabetes has been linked to cognitive impairment, but its potential metabolic mechanism is still unclear. The present study aimed to explore neuron-astrocyte metabolic cooperation in the brain of diabetic (db/db, BKS.Cg-m +/+ Leprdb/J) mice with cognitive decline using 13 C NMR technique in combination with intravenous [2- 13 C]-acetate and [3- 13 C]-lactate infusions. We found that the 13 C-enrichment from [2- 13 C]-acetate into tricarboxylic acid cycle intermediate, succinate, was significantly decreased in db/db mice with cognitive decline compared with wild-type (WT, C57BLKS/J) mice, while an opposite result was obtained after [3- 13 C]-lactate infusion. Relative to WT mice, db/db mice with cognitive decline had significantly lower 13 C labeling percentages in neurotransmitters including glutamine, glutamate, and γ-aminobutyric acid after [2- 13 C]-acetate infusion. However, [3- 13 C]-lactate resulted in increased 13 C-enrichments in neurotransmitters in db/db mice with cognitive decline. This may indicate that the disturbance of neurotransmitter metabolism occurred during the development of cognitive decline. In addition, a reduction in 13 C-labeling of lactate and an increase in gluconeogenesis were found from both labeled infusions in db/db mice with cognitive decline. Therefore, our results suggest that the development of cognitive decline in type 2 diabetes may be implicated to an unbalanced metabolism in neuron-astrocyte cooperation and an enhancement of gluconeogenesis. © The Author(s) 2016.

Synthesis of ring-13C-labelled and ring-demethylated retinals

International Nuclear Information System (INIS)

Courtin, J.M.L.

1988-01-01

Efficient synthetic schemes are described for the preparation of the required mono- and di- 13 C labelled retinals based on simple 13 C labelled starting materials. Results from solid-state 13 C-NMR spectroscopic studies of the various ring- 13 C labelled bacteriorhodopsins and rhodopsins are discussed. 404 refs.; 74 figs.; 16 tabs

Proton chemical shift tensors determined by 3D ultrafast MAS double-quantum NMR spectroscopy

International Nuclear Information System (INIS)

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

2015-01-01

Proton NMR spectroscopy in the solid state has recently attracted much attention owing to the significant enhancement in spectral resolution afforded by the remarkable advances in ultrafast magic angle spinning (MAS) capabilities. In particular, proton chemical shift anisotropy (CSA) has become an important tool for obtaining specific insights into inter/intra-molecular hydrogen bonding. However, even at the highest currently feasible spinning frequencies (110–120 kHz), 1 H MAS NMR spectra of rigid solids still suffer from poor resolution and severe peak overlap caused by the strong 1 H– 1 H homonuclear dipolar couplings and narrow 1 H chemical shift (CS) ranges, which render it difficult to determine the CSA of specific proton sites in the standard CSA/single-quantum (SQ) chemical shift correlation experiment. Herein, we propose a three-dimensional (3D) 1 H double-quantum (DQ) chemical shift/CSA/SQ chemical shift correlation experiment to extract the CS tensors of proton sites whose signals are not well resolved along the single-quantum chemical shift dimension. As extracted from the 3D spectrum, the F1/F3 (DQ/SQ) projection provides valuable information about 1 H– 1 H proximities, which might also reveal the hydrogen-bonding connectivities. In addition, the F2/F3 (CSA/SQ) correlation spectrum, which is similar to the regular 2D CSA/SQ correlation experiment, yields chemical shift anisotropic line shapes at different isotropic chemical shifts. More importantly, since the F2/F1 (CSA/DQ) spectrum correlates the CSA with the DQ signal induced by two neighboring proton sites, the CSA spectrum sliced at a specific DQ chemical shift position contains the CSA information of two neighboring spins indicated by the DQ chemical shift. If these two spins have different CS tensors, both tensors can be extracted by numerical fitting. We believe that this robust and elegant single-channel proton-based 3D experiment provides useful atomistic-level structural and dynamical

Recent advances in solid state NMR and its application to ceramics

International Nuclear Information System (INIS)

Maekawa, Hideki

2006-01-01

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

Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

Energy Technology Data Exchange (ETDEWEB)

Chagas, L.H.; De Carvalho, G.S.G. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); San Gil, R.A.S. [Universidade Federal do Rio de Janeiro, Instituto de Química, 21949-900 Rio de Janeiro, RJ (Brazil); Chiaro, S.S.X. [PETROBRAS-CENPES, 21941-915 Rio de Janeiro, RJ (Brazil); Leitão, A.A. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); Diniz, R., E-mail: renata.diniz@ufjf.edu.br [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil)

2014-01-01

Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

13C NMR relaxation times of hepatic glycogen in vitro and in vivo

International Nuclear Information System (INIS)

Zang, Lihsin; Laughlin, M.R.; Rothman, D.L.; Shulman, R.G.

1990-01-01

The field dependence of relaxation times of the C-1 carbon of glycogen was studied in vitro by natural-abundance 13 C NMR. T 1 is strongly field dependent, while T 2 does not change significantly with magnetic field. T 1 and T 2 were also measured for rat hepatic glycogen enriched with [1- 13 C]glucose in vivo at 4.7 T, and similar relaxation times were observed as those obtained in vitro at the same field. The in vitro values of T 1 were 65 ± 5 ms at 2.1 T, 142 ± 10 ms at 4.7 T, and 300 ± 10 ms at 8.4 T, while T 2 values were 6.7 ± 1 ms at 2.1 T, 9.4 ± 1 ms at 4.7 T, and 9.5 ± 1 ms at 8.4 T. Calculations based on the rigid-rotor nearest-neighbor model give qualitatively good agreement with the T 1 field dependence with a best-fit correlation time of 6.4 x 10 -9 s, which is significantly smaller than τ M , the estimated overall correlation time for the glycogen molecule (ca. 10 -5 s). A more accurate fit of T 1 data using a modified Lipari and Szabo approach indicates that internal fast motions dominate the T 1 relaxation in glycogen. On the other hand, the T 2 relaxation is dominated by the overall correlation time τ M while the internal motions are almost but not completely unrestricted

Analysis of the mechanical properties and characterization by solid state 13 C NMR of recycled EVA copolymer/silica composites

International Nuclear Information System (INIS)

Stael, Giovanni Chaves; Rocha, Marisa Cristina Guimaraes

2005-01-01

The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate) - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM), and the 13 C Nuclear Magnetic Resonance (NMR) showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group. (author)

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

Science.gov (United States)

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

2016-01-04

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

Identification and quantitative determination of carbohydrates in ethanolic extracts of two conifers using 13C NMR spectroscopy.

Science.gov (United States)

Duquesnoy, Emilie; Castola, Vincent; Casanova, Joseph

2008-04-07

We developed a method for the direct identification and quantification of carbohydrates in raw vegetable extracts using (13)C NMR spectroscopy without any preliminary step of precipitation or reduction of the components. This method has been validated (accuracy, precision and response linearity) using pure compounds and artificial mixtures before being applied to authentic ethanolic extracts of pine needles, pine wood and pine cones and fir twigs. We determined that carbohydrates represented from 15% to 35% of the crude extracts in which pinitol was the principal constituent accompanied by arabinitol, mannitol, glucose and fructose.

Applications of artificial intelligence techniques to organic chemistry. Study on 13C NMR of steroids using computer

International Nuclear Information System (INIS)

Lins, A.P.; Furlan, M.; Gastmans, G.P.; Emerenciano, V.P.

1991-01-01

This work describes the utilization of two groups of programs in searching for characteristic signals of NMR 13 C steroidal compounds. The first group of programs used data bases with the spectral data and a methodology that enables the choice and the search of substructures. The chemical shifts and multiplicities for each specific substructure are used as rules to identify different types and subtypes of steroidal compounds. The second one was built to apply the rules formulated by the first group of programs and to foresee any skeletal based on a spectral analysis. (author)

Halogen effect on structure and ¹³C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

DEFF Research Database (Denmark)

Radula-Janik, Klaudia; Kupka, Teobald; Ejsmont, Krzysztof

2013-01-01

Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory and their 13C NMR isotropic nuclear shieldings were predicted using density functional theory (DFT). The model compounds contained 9H-, N-methyl and N-ethyl derivatives...

Mechanism of Phenol Alkylation in Zeolite H-BEA Using In Situ Solid-State NMR Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zhao, Zhenchao [Institute; Shi, Hui [Institute; Wan, Chuan [Institute; Hu, Mary Y. [Institute; Liu, Yuanshuai [Department; Mei, Donghai [Institute; Camaioni, Donald M. [Institute; Hu, Jian Zhi [Institute; Lercher, Johannes A. [Institute; Department

2017-06-27

Alkylation of phenolic compounds in the liquid phase is of fundamental and practical importance to the conversion of biomass-derived feedstocks into fuels and chemicals. In this work, the reaction mechanism for phenol alkylation with cyclohexanol and cyclohexene has been investigated on a commercial HBEA zeolite by in situ 13C MAS NMR, using decalin as the solvent. From the variable temperature 13C MAS NMR measurements of phenol and cyclohexanol adsorption on HBEA from decalin solutions, it is shown that the two molecules have similar adsorption strength in the HBEA pore. Phenol alkylation with cyclohexanol, however, becomes significantly measurable only after cyclohexanol is largely converted to cyclohexene via dehydration. This is in contrast to the initially rapid alkylation of phenol when using cyclohexene as the co-reactant. 13C isotope scrambling results demonstrate that the electrophile, presumably cyclohexyl carbenium ion, is directly formed in a protonation step when cyclohexene is the co-reactant, but requires re-adsorption of the alcohol dehydration product, cyclohexene, when cyclohexanol dimer is the dominant surface species (e.g., at 0.5 M cyclohexanol concentration) that is unable to generate carbenium ion. At the initial reaction stage of phenol-cyclohexanol alkylation on HBEA, the presence of the cyclohexanol dimer species hinders the adsorption of cyclohexene at the Brønsted acid site and the subsequent activation of the more potent electrophile (carbenium ion). Isotope scrambling data also show that intramolecular rearrangement of cyclohexyl phenyl ether, the O-alkylation product, does not significantly contribute to the formation of C-alkylation products.

/sup 1/H, /sup 13/C and /sup 31/P-NMR spectroscopic study of glucose metabolism of muscle larva Trichinella spiralis (U. S. A. strain), and the effects of the end-products on the host (mouse)

Energy Technology Data Exchange (ETDEWEB)

Nishina, Masami

1988-11-01

/sup 1/H- and /sup 13/C-nuclear magnetic resonance (NMR) spectroscopy was used to identify and quantitate metabolites excreted by muscle larva Trichinella spiralis maintained aerobically in the presence of D- (/sup 13/C/sub 6/) glucose and (1, 1'-/sup 13/C/sub 2/) succinate. End-products of glucose metabolism studied by /sup 1/H-NMR were lactate, acetate, succinate, proionate, n-valerate and alanine, at the molar ratio of 1:2:1:0.6:0.5:0.6. /sup 13/C-NMR measurement proved that all the products originated from the glucose in the medium via the phosphoenolpyruvate carboxykinase-succinate pathway and the tricarboxylic acid cycle. In vivo /sup 31/P-NMR spectra were also taken by the surface coil method from the leg muscle of mice which had been infected with T. spiralis. Intracelluar pH and relative amount of ATP in the leg muscle of the infected mice were found to decrease significantly as compared with that of control mice.

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

NARCIS (Netherlands)

Oosthoek-de Vries, Anna Jo; Bart, Jacob; Tiggelaar, Roald M.; Janssen, Johannes W.G.; van Bentum, Jan (P.J.M.); Gardeniers, Han J.G.E.; Kentgens, Arno P.M.

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

Characterization of threonine side chain dynamics in an antifreeze protein using natural abundance {sup 13}C NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Daley, Margaret E.; Sykes, Brian D. [University of Alberta, Department of Biochemistry, CIHR Group in Protein Structure and Function and Protein Engineering Network of Centres of Excellence (Canada)

2004-06-15

The dynamics of threonine side chains of the Tenebrio molitor antifreeze protein (TmAFP) were investigated using natural abundance {sup 13}C NMR. In TmAFP, the array of threonine residues on one face of the protein is responsible for conferring its ability to bind crystalline ice and inhibit its growth. Heteronuclear longitudinal and transverse relaxation rates and the {sup 1}H-{sup 13}C NOE were determined in this study. The C{alpha}H relaxation measurements were compared to the previously measured {sup 15}N backbone parameters and these are found to be in agreement. For the analysis of the threonine side chain motions, the model of restricted rotational diffusion about the {chi}{sub 1} dihedral angle was employed [London and Avitabile (1978) J. Am. Chem. Soc., 100, 7159-7165]. We demonstrate that the motion experienced by the ice binding threonine side chains is highly restricted, with an approximate upper limit of less than {+-}25 deg.

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

Czech Academy of Sciences Publication Activity Database

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

2012-01-01

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

Characterization of threonine side chain dynamics in an antifreeze protein using natural abundance 13C NMR spectroscopy

International Nuclear Information System (INIS)

Daley, Margaret E.; Sykes, Brian D.

2004-01-01

The dynamics of threonine side chains of the Tenebrio molitor antifreeze protein (TmAFP) were investigated using natural abundance 13 C NMR. In TmAFP, the array of threonine residues on one face of the protein is responsible for conferring its ability to bind crystalline ice and inhibit its growth. Heteronuclear longitudinal and transverse relaxation rates and the 1 H- 13 C NOE were determined in this study. The CαH relaxation measurements were compared to the previously measured 15 N backbone parameters and these are found to be in agreement. For the analysis of the threonine side chain motions, the model of restricted rotational diffusion about the χ 1 dihedral angle was employed [London and Avitabile (1978) J. Am. Chem. Soc., 100, 7159-7165]. We demonstrate that the motion experienced by the ice binding threonine side chains is highly restricted, with an approximate upper limit of less than ±25 deg

Nano-mole scale sequential signal assignment by 1 H-detected protein solid-state NMR

KAUST Repository

Wang, Songlin; Parthasarathy, Sudhakar; Xiao, Yiling; Nishiyama, Yusuke; Long, Fei; Matsuda, Isamu; Endo, Yuki; Nemoto, Takahiro; Yamauchi, Kazuo; Asakura, Tetsuo; Takeda, Mitsuhiro; Terauchi, Tsutomu; Kainosho, Masatsune; Ishii, Yoshitaka

2015-01-01

We present a 3D 1H-detected solid-state NMR (SSNMR) approach for main-chain signal assignments of 10-100 nmol of fully protonated proteins using ultra-fast magic-angle spinning (MAS) at ∼80 kHz by a novel spectral-editing method, which permits drastic spectral simplification. The approach offers ∼110 fold time saving over a traditional 3D 13C-detected SSNMR approach. This journal is © The Royal Society of Chemistry 2015.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

NMR 1H,13C, 15N backbone and 13C side chain resonance assignment of the G12C mutant of human K-Ras bound to GDP.

Science.gov (United States)

Sharma, Alok K; Lee, Seung-Joo; Rigby, Alan C; Townson, Sharon A

2018-05-02

K-Ras is a key driver of oncogenesis, accounting for approximately 80% of Ras-driven human cancers. The small GTPase cycles between an inactive, GDP-bound and an active, GTP-bound state, regulated by guanine nucleotide exchange factors and GTPase activating proteins, respectively. Activated K-Ras regulates cell proliferation, differentiation and survival by signaling through several effector pathways, including Raf-MAPK. Oncogenic mutations that impair the GTPase activity of K-Ras result in a hyperactivated state, leading to uncontrolled cellular proliferation and tumorogenesis. A cysteine mutation at glycine 12 is commonly found in K-Ras associated cancers, and has become a recent focus for therapeutic intervention. We report here 1 H N, 15 N, and 13 C resonance assignments for the 19.3 kDa (aa 1-169) human K-Ras protein harboring an oncogenic G12C mutation in the GDP-bound form (K-RAS G12C-GDP ), using heteronuclear, multidimensional NMR spectroscopy. Backbone 1 H- 15 N correlations have been assigned for all non-proline residues, except for the first methionine residue.

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.

Analysis of the mechanical properties and characterization by solid state 13C NMR of recycled EVA copolymer/silica composites

Directory of Open Access Journals (Sweden)

Giovanni Chaves Stael

2005-09-01

Full Text Available The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM, and the 13C Nuclear Magnetic Resonance (NMR showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group.