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1

Phosphorus solubility of agricultural soils: a surface charge and phosphorus-31 NMR speciation study  

Technology Transfer Automated Retrieval System (TEKTRAN)

We investigated ten soils from six states in United States to determine the relationship between potentiometric titration derived soil surface charge and Phosphorus-31 (P) nuclear magnetic resonance (NMR) speciation with the concentration of water-extractable P (WEP). The surface charge value at the...

2

Phosphonato complexes of platinum(II): kinetics of formation and phosphorus-31 NMR characterization studies  

Microsoft Academic Search

Reactions of cis-diamminedichloroplatinum(II) with phosphonoformic acid (PFA), phosphonoacetic acid (PAA), and methylenediphosphonic acid (MDP) yield various phosphonatoplatinum(II) chelates which were characterized by phosphorus-31 NMR spectroscopy. The P-31 resonances for the chelates appear at 6-12 ppm downfield as compared to the uncomplexed ligands. All complexes exhibit monoprotic acidic behavior in the pH range 2-10. The chemical shift-pH profiles yielded acidity constants,

L. L. Slavin; R. N. Bose

1990-01-01

3

Phosphonato complexes of platinum(II): kinetics of formation and phosphorus-31 NMR characterization studies  

SciTech Connect

Reactions of cis-diamminedichloroplatinum(II) with phosphonoformic acid (PFA), phosphonoacetic acid (PAA), and methylenediphosphonic acid (MDP) yield various phosphonatoplatinum(II) chelates which were characterized by phosphorus-31 NMR spectroscopy. The P-31 resonances for the chelates appear at 6-12 ppm downfield as compared to the uncomplexed ligands. All complexes exhibit monoprotic acidic behavior in the pH range 2-10. The chemical shift-pH profiles yielded acidity constants, 1.0 x 10(-4), 1.5 x 10(-4), and 1.3 x 10(-6) M-1, for the PFA, PAA, and MDP chelates. In addition to the monomeric chelate, MDP formed a bridged diplatinum(II,II) complex when it reacted with cis-Pt (NH3)2(H2O)2(2)+. The P-31 resonance for this binuclear complex appears at 22 ppm downfield from the unreacted ligand. Rate data for the complexation reactions of the phosphonate ligands with the dichloroplatinum complex are consistent with a mechanism in which a monodentate complex is formed initially through rate-limiting aquation process of the platinum complex, followed by a rapid chelation. For the PFA and PAA complexes, initial binding sites are the carboxylato oxygens. Implications of the various binding modes of the phosphonates in relationship to their antiviral activities are discussed.

Slavin, L.L.; Bose, R.N. (Chemistry Department, Kent State University, OH (USA))

1990-12-01

4

Phosphonato complexes of platinum(II): kinetics of formation and phosphorus-31 NMR characterization studies.  

PubMed

Reactions of cis-diamminedichloroplatinum(II) with phosphonoformic acid (PFA), phosphonoacetic acid (PAA), and methylenediphosphonic acid (MDP) yield various phosphonatoplatinum(II) chelates which were characterized by phosphorus-31 NMR spectroscopy. The P-31 resonances for the chelates appear at 6-12 ppm downfield as compared to the uncomplexed ligands. All complexes exhibit monoprotic acidic behavior in the pH range 2-10. The chemical shift-pH profiles yielded acidity constants, 1.0 x 10(-4), 1.5 x 10(-4), and 1.3 x 10(-6) M-1, for the PFA, PAA, and MDP chelates. In addition to the monomeric chelate, MDP formed a bridged diplatinum(II,II) complex when it reacted with cis-Pt (NH3)2(H2O)2(2)+. The P-31 resonance for this binuclear complex appears at 22 ppm downfield from the unreacted ligand. Rate data for the complexation reactions of the phosphonate ligands with the dichloroplatinum complex are consistent with a mechanism in which a monodentate complex is formed initially through rate-limiting aquation process of the platinum complex, followed by a rapid chelation. For the PFA and PAA complexes, initial binding sites are the carboxylato oxygens. Implications of the various binding modes of the phosphonates in relationship to their antiviral activities are discussed. PMID:2150856

Slavin, L L; Bose, R N

1990-12-01

5

Synthesis and characterization of polyphosphazene copolymers using phosphorus-31 NMR spectroscopy  

SciTech Connect

It was observed that competitive nucleophilic addition processes may be observed by {sup 31}P NMR spectroscopy. Methoxyethoxyethanol (MEE) and p-methoxyphenol readily substitute for chlorineonto phosphorus and the relative rates are generally comparable to each other. Sterically, the phenol presents is slightly larger than MEE but this does not appear to effect substitution judging by the observed PN(OAr){sub 2} NMR signal. These processes are still being studied.

Stewart, F.F.; Peterson, E.S.; Stone, M.L. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States); Singler, R.E. [Military Academy, West Point, NY (United States). Dept. of Chemistry

1997-01-01

6

Contribution of protein phosphorylation to binding-induced folding of the SLBP–histone mRNA complex probed by phosphorus-31 NMR  

PubMed Central

Phosphorus-31 (31P) NMR can be used to characterize the structure and dynamics of phosphorylated proteins. Here, I use 31P NMR to report on the chemical nature of a phosphothreonine that lies in the RNA binding domain of SLBP (stem-loop binding protein). SLBP is an intrinsically disordered protein and phosphorylation at this threonine promotes the assembly of the SLBP–RNA complex. The data show that the 31P chemical shift can be a good spectroscopic probe for phosphate-coupled folding and binding processes in intrinsically disordered proteins, particularly where the phosphate exhibits torsional strain and is involved in a network of hydrogen-bonding interactions. PMID:25379382

Thapar, Roopa

2014-01-01

7

A high-resolution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopic method for the non-phosphorus markers of chemical warfare agents.  

PubMed

A high-resolution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopic method has been developed for detection, identification and quantification of non-phosphorus markers of toxic nerve agents (soman and V-class), vesicants (HD, HN-2, HN-3), and incapacitating agent (Bz). These analytes were converted to phosphorus-containing derivatives via phosphitylation reaction of their hydroxyl and sulfhydryl functions (using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane). This was followed by (31)P{(1)H} and (31)P NMR analysis of these derivatives. The chemical shifts (?) and coupling constants ((3)J(P-H)) of derivatives were used for their specific detection and identification. The method allowed clear distinction between the alcohols and thiols. The lower limits of detection of these analytes were found to be between 12 and 28 ?g obtained from 128 transients of (31)P{(1)H} quantitative NMR experiments. Utility of the method was ensured by the detection and identification of triethanolamine present (at an original concentration of 5 ?g/mL) in an aqueous sample from 28th OPCW Official Proficiency Tests. PMID:22160203

Mazumder, Avik; Kumar, Ajeet; Purohit, Ajay K; Dubey, Devendra K

2012-02-01

8

Sodium transport and phosphorus metabolism in sodium-loaded yeast: simultaneous observation with sodium-23 and phosphorus-31 NMR spectroscopy in vivo  

SciTech Connect

Simultaneous /sup 23/Na and /sup 31/P NMR spectra were obtained from a number of yeast suspensions. Prior to NMR spectroscopy, the yeast cells were Na-loaded: this replaced some of the intracellular K/sup +/ with Na/sup +/. These cells were also somewhat P-deficient in that they had no polyphosphate species visible in the /sup 31/P NMR spectrum. In the NMR experiments, the Na-loaded cells were suspended in media which contained inorganic phosphate, very low Na/sup +/, a shift reagent for the Na/sup +/ NMR signal. The media differed as to whether dioxygen, glucose, or K/sup +/ was present individually or in combinations and as to whether the medium was buffered or not. The NMR spectra revealed that the cells always lost Na/sup +/ and gained phosphorus. However, the nature of the Na/sup +/ efflux time course and the P metabolism differed depending on the medium. The Na/sup +/ efflux usually proceeded linearly until the amount of Na/sup +/ extruded roughly equaled the amount of NH/sub 4//sup +/ and orthophosphate initially present in the medium. The Na/sup +/ efflux then entered a transition phase, either slowing, ceasing, or transiently reversing, before resuming at about the same value as that of the first phase. The phosphorus metabolism was much more varied. These changes are interpreted in terms of hierarchical energy demands on the cells under the different conditions. In particular, the energy for the Na/sup +/ for NH/sub 4//sup +/ exchange takes precedence over that required to produce and store polyphosphate. This conclusion is supported by the fact that when the cells are forced to exchange K/sup +/, as well as NH/sub 4//sup +/, for Na/sup +/ polyphosphates are never significantly formed, and the initial linear Na/sup +/ efflux phase persists possibly 6 times as long.

Hoefeler, H.; Jensen, D.; Pike, M.M.; Delayre, J.L.; Cirillo, V.P.; Springer, C.S. Jr.; Fossel, E.T.; Balschi, J.A.

1987-08-11

9

Mechanism of adenylate kinase. Demonstration of a functional relationship between aspartate 93 and Mg2+ by site-directed mutagenesis and proton, phosphorus-31, and magnesium-25 NMR.  

PubMed

Earlier magnetic resonance studies suggested no direct interaction between Mg2+ ions and adenylate kinase (AK) in the AK.MgATP (adenosine 5'-triphosphate) complex. However, recent NMR studies concluded that the carboxylate of aspartate 119 accepts a hydrogen bond from a water ligand of the bound Mg2+ ion in the muscle AK.MgATP complex [Fry, D.C., Kuby, S.A., & Mildvan, A.S. (1985) Biochemistry 24, 4680-4694]. On the other hand, in the 2.6-A crystal structure of the yeast AK.MgAP5A [P1,P5-bis(5'-adenosyl)pentaphosphate] complex, the Mg2+ ion is in proximity to aspartate 93 [Egner, U., Tomasselli, A.G., & Schulz, G.E. (1987) J. Mol. Biol. 195, 649-658]. Substitution of Asp-93 with alanine resulted in no change in dissociation constants, 4-fold increases in Km, and a 650-fold decrease in kcat. Notable changes have been observed in the chemical shifts of the aromatic protons of histidine 36 and a few other aromatic residues. However, the results of detailed analyses of the free enzymes and the AK.MgAP5A complexes by one- and two-dimensional NMR suggested that the changes are due to localized perturbations. Thus it is concluded that Asp-93 stabilizes the transition state by ca. 3.9 kcal/mol. The next question is how. Since proton NMR results indicated that binding of Mg2+ to the AK.AP5A complex induces some changes in the proton NMR signals of WT but not those of D93A, the functional role of Asp-93 should be in binding to Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2036423

Yan, H G; Tsai, M D

1991-06-01

10

Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca1  

PubMed Central

Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in 31P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by 14N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate. PMID:16666713

Lundberg, Peter; Weich, Rainer G.; Jensén, Paul; Vogel, Hans J.

1989-01-01

11

Mechanism of adenylate kinase. Demonstration of a functional relationship between aspartate 93 and Mg sup 2+ by site-directed mutagenesis and proton, phosphorus-31, and magnesium-25 NMR  

SciTech Connect

Earlier magnetic resonance studies suggested no direct interaction between Mg{sup 2+} ions and adenylate kinase (AK) in the AK{center dot}MgATP (adenosine 5'-triphosphate) complex. However, recent NMR studies concluded that the carboxylate of aspartate 119 accepts a hydrogen bond from a water ligand of the bound Mg{sup 2+} ion in the muscle AK {center dot} MgATP complex. On the other hand, in the 2.6-{angstrom} crystal structure of the yeast AK{center dot}MgAP{sub 5}A (P{sup 1}, P{sup 5}-bis(5'-adenosyl)pentaphosphate) complex, the Mg{sup 2+} ion is in proximity to aspartate 93. Substitution of Asp-93 with alanine resulted in no change in dissociation constants, 4-fold increases in K{sub m}, and a 650-fold decrease in k{sub cat}. Notable changes have been observed in the chemical shifts of the aromatic protons of histidine 36 and a few other aromatic residues. However, the results of detailed analyses of the free enzymes and the AK{center dot}MgAP{sub 5}A complexes by one- and two-dimensional NMR suggested that the changes are due to localized perturbations. Thus it is concluded that Asp-93 stabilizes the transition state by ca. 3.9 kcal/mol. Other results raised the question of whether Mg{sup 2+} could bind to D93A{center dot}nucleotide complexes, which was then probed by {sup 25}MgNMR. The results suggest that Mg{sup 2+} does bind to the D93A{center dot}AP{sub 5}A complex, but possibly only weakly.

Yan, Honggao; Tsai, Mingdaw (Ohio State Univ., Columbus (United States))

1991-06-04

12

Flavodoxin from Anabaena 7120: uniform nitrogen-15 enrichment and hydrogen-1, nitrogen-15, and phosphorus-31 NMR investigation of the flavin mononucleotide binding site in the reduced and oxidized states  

SciTech Connect

Interactions between flavin mononucleotide (FMN) and apoprotein have been investigated in the reduced and oxidized states of the flavodoxin isolated from Anabaena 7120 (M/sub r/ approx. 21,000). /sup 1/H, /sup 15/N, and /sup 31/P NMR have been used to characterize the FMN-protein interactions in both redox states. These are compared with those seen in other flavodoxins. Uniformly enriched (/sup 15/N) flavodoxin was isolated from Anabaena 7120 grown on K/sup 15/NO/sub 3/ as the sole nitrogen source. /sup 15/N insensitive nucleus enhanced by polarization transfer (INEPT) and nuclear Overhauser effect (NOE) studies of this sample provided information regarding protein structure and dynamics. A /sup 1/H-detected /sup 15/N experiment allowed the correlation of nitrogen resonances to those of their attached protons. Over 90% of the expected N-H cross peaks could be resolved in this experiment.

Stockman, B.J.; Westler, W.M.; Mooberry, E.S.; Markley, J.L.

1988-01-12

13

The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [31  

E-print Network

1617 The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [31 P; Shober et al., 2006; Toor et al., 2005a, 2005b) and solid-state phosphorus-31 nuclear magnetic resonance

Sparks, Donald L.

14

The solution structure of Ln (DOTP) 5- complexxes. A comparison of lanthanide-induced paramagnetic shifts with the MMX energy-minimized structure  

NASA Astrophysics Data System (ADS)

Complexes between the trivalent lanthanide ions and the macrocyclic chelate 1,4,7,10-tetraazacyclododecane- N,N',N?,N?-tetra(methylene phosphonate) (DOTP) have been examined by high-resolution NMR spectroscopy. The proton spectra of the diamagnetic La(DOTP) 5- and Lu(DOTP) 5- complexes provide evidence for very rigid chelate structures with the ethylenediamine-containing chelate rings essentially locked into a single conformation at room temperature. The activation energy for ethylenediamine chelate ring interconversions in these complexes is approximately 100 kJ mol -1, considerably higher than that reported previously for the corresponding Ln(DOTA) - complexes (DOTA is the tetraacetate analog of DOTP). Lanthanide-induced shifts are reported for all 1H, 13C, and 31P nuclei in 11 Ln(DOTP) 5- complexes. The proton spectra of these complexes display unusually large lanthanide-induced shifts, one showing a spectrum in which the 1H resonances span 900 ppm. The contact and pseudocontact contributions to these shifts were separated using Reilley's temperature-independent method and the resulting pseudocontact lanthanide-induced NMR shifts were in excellent agreement with those calculated for a structure derived using MMX molecular modeling methods. The pseudocontact shifts provide evidence for Ln (DOTP) 5- chelates which have virtually identical structures along the lanthanide series, with the possible exception of Tm(DOTP) 5-.

Geraldes, Carlos F. G. C.; Sherry, A. Dean; Kiefer, Garry E.

15

Deuterium and phosphorus-31 nuclear magnetic resonance study of the interaction of melittin with dimyristoylphosphatidylcholine bilayers and the effects of contaminating phospholipase A/sub 2/  

SciTech Connect

The interaction of bee venom melittin with dimyristoylphosphatidylcholine (DMPC) selectively deuteriated in the choline head group has been studied by deuterium and phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy. The action of residual phospholipase A/sub 2/ in melittin samples resulted in mixtures of DMPC and its hydrolytic products that underwent reversible transitions at temperatures between 30 and 35/sup 0/C from extended bilayers to micellar particles which gave narrow single-line deuterium and phosphorus-31 NMR spectra. Similar transitions were observed in DMPC-myristoyllysophosphatidylcholine (lysoPC)-myristic acid mixtures containing melittin but not in melittin-free mixtures, indicating that melittin is able to stabilize extended bilayers containing DMPC and its hydrolytic products in the liquid-crystalline phase. Melittin, free of phospholipase A/sub 2/ activity, and at 3-5 mol % relative to DMPC, induced reversible transitions between extended bilayers and micellar particles on passing through the liquid-crystalline to gel phase transition temperature of the lipid, effects similar to those observed in melittin-acyl chain deuteriated dipalmitoylphosphatidylcholine (DPPC) mixtures. LysoPC at concentrations of 20 mol % or greater relative to DMPC induced transitions between extended bilayers and micellar particles with characteristics similar to those induced by melittin. It is proposed that these melittin- and lysoPC-induced transitions share similar mechanisms. The effects of melittin on the quadrupole splittings and T/sub 1/ relaxation times of head-group-deuteriated DMPC in the liquid-crystalline phase share features similar to the effects of metal ions on DPPC head groups, indicating that the conformational properties of the choline head group in PC bilayers may be affected by melittin and by metal ions in a similar manner.

Dempsey, C.E.; Watts, A.

1987-09-08

16

Dynamics of phosphate head groups in biomembranes. Comprehensive analysis using phosphorus-31 nuclear magnetic resonance lineshape and relaxation time measurements.  

PubMed Central

Phospholipid head group dynamics have been studied by pulsed phosphorus-31 nuclear magnetic resonance (31P-NMR) of unoriented and macroscopically aligned dimyristoylphosphatidylcholine model membranes in the temperature range, 203-343 K. Lineshapes and echo intensities have been recorded as a function of interpulse delay times, temperature and macroscopic orientation of the bilayer normal with respect to the magnetic field. The dipolar proton-phosphorus (1H-31P) contribution to the transverse relaxation time, T2E, and to lineshapes was eliminated by means of a proton spin-lock sequence. In case of longitudinal spin relaxation, T1Z, the amount of dipolar coupling was evaluated by measuring the maximum nuclear Overhauser enhancement. Hence, the results could be analyzed by considering chemical shift anisotropy as the only relaxation mechanism. The presence of various minima both in T1Z and T2E temperature plots as well as the angular dependence of these relaxation times allowed description of the dynamics of the phosphate head group in the 31P-NMR time window, by three different motional classes, i.e., intramolecular, intermolecular and collective motions. The intramolecular motions consist of two hindered rotations and one free rotation around the bonds linking the phosphate head group to the glycerol backbone. These motions are the fastest in the hierarchy of time with correlation times varying from less than 10(-12) to 10(-6) s in the temperature range investigated. The intermolecular motions are assigned to phospholipid long axis rotation and fluctuation. They have correlation times ranging from 10(-11) s at high temperatures to 10(-3) s at low temperatures. The slowest motion affecting the 31P-NMR observables is assigned to viscoelastic modes, i.e., so called order director fluctuations and is only detected at high temperatures, above the main transition in pulse frequency dependent T2ECP experiments. Comprehensive analysis of the phosphate head group dynamics is achieved by a dynamic NMR model based on the stochastic Liouville equation. In addition to correlation times, this analysis provides activation energies and order parameters for the various motions, and a value for the bilayer elastic constant. PMID:1540698

Dufourc, E J; Mayer, C; Stohrer, J; Althoff, G; Kothe, G

1992-01-01

17

Phosphorus-31 MRI of hard and soft solids using quadratic echo line-narrowing  

PubMed Central

Magnetic resonance imaging (MRI) of solids is rarely attempted. One of the main reasons is that the broader MR linewidths, compared to the narrow resonance of the hydrogen (1H) in free water, limit both the attainable spatial resolution and the signal-to-noise ratio. Basic physics research, stimulated by the quest to build a quantum computer, gave rise to a unique MR pulse sequence that offers a solution to this long-standing problem. The “quadratic echo” significantly narrows the broad MR spectrum of solids. Applying field gradients in sync with this line-narrowing sequence offers a fresh approach to carry out MRI of hard and soft solids with high spatial resolution and with a wide range of potential uses. Here we demonstrate that this method can be used to carry out three-dimensional MRI of the phosphorus (31P) in ex vivo bone and soft tissue samples. PMID:22431609

Frey, Merideth A.; Michaud, Michael; VanHouten, Joshua N.; Insogna, Karl L.; Madri, Joseph A.; Barrett, Sean E.

2012-01-01

18

Phosphorus31 nuclear magnetic resonance of double- and triple-helical nucleic acids. Phosphorus31 chemical shifts as a probe of phosphorus-oxygen ester bond torsional angles  

Microsoft Academic Search

The temperature dependence to the ³¹P NMR spectra of poly(d(GC))-poly(d(GC)), d(GC)â, phenylalanine tRNA (yeast) and mixtures of poly(A) + oligo(U) is presented. The ³¹P NMR spectra of mixtures of complementary RNA and of the poly d(GC) self-complementary DNA provide torsional information on the phosphate ester conformation in the double, triple, and ''Z'' helix. The increasing downfield shift with temperature for

D. G. Gorenstein; B. A. Luxon; E. M. Goldfield; K. Lai; D. Vegeais

1982-01-01

19

Phosphorus-31 nuclear magnetic resonance spectroscopic study of the canine pancreas: applications to acute alcoholic pancreatitis  

SciTech Connect

The first nuclear magnetic resonance spectroscopic study of the canine pancreas is described. Both in-vivo, ex-vivo protocols and NMR observables are discussed. The stability of the ex-vivo preparation based on the NMR observables is established for at least four hours. The spectra obtained from the in-vivo and ex-vivo preparations exhibited similar metabolite ratios, further validating the model. Metabolite levels were unchanged by a 50% increase in perfusion rate. Only trace amounts of phosphocreatine were observed either in the intact gland or in extracts. Acute alcoholic pancreatitis was mimicked by free fatty acid infusion. Injury resulted in hyperamylasemia, edema (weight gain), increased hematocrit and perfusion pressure, and depressed levels of high energy phosphates.

Janes, N.; Clemens, J.A.; Glickson, J.D.; Cameron, J.L.

1988-01-01

20

Phosphorus-31 MRI of bones using quadratic echo line-narrowing  

NASA Astrophysics Data System (ADS)

There is a great need to probe the internal composition of bone on the sub-0.1 mm length scale, both to study normal features and to look for signs of disease. Despite the obvious importance of the mineral fraction to the biomechanical properties of skeletal tissue, few non-destructive techniques are available to evaluate changes in its chemical structure and functional microarchitecture on the interior of bones. MRI would be an excellent candidate, but bone is a particularly challenging tissue to study given the relatively low water density and wider linewidths of its solid components. Recent fundamental research in quantum computing gave rise to a new NMR pulse sequence - the quadratic echo - that can be used to narrow the broad NMR spectrum of solids. This offers a new route to do high spatial resolution, 3D ^31P MRI of bone that complements conventional MRI and x-ray based techniques to study bone physiology and structure. We have used our pulse sequence to do 3D ^31P MRI of ex vivo bones with a spatial resolution of (sub-450 ?m)^3, limited only by the specifications of a conventional 4 Tesla liquid-state MRI system. We will describe our plans to push this technique towards the factor of 1000 increase in spatial resolution imposed by fundamental limits.

Frey, Merideth; Barrett, Sean; Insogna, Karl; Vanhouten, Joshua

2012-02-01

21

Phosphorus-31 Nuclear Magnetic Resonance Study of the Effect of Pentachlorophenol (PCP) on the Physiologies of PCP-Degrading Microorganisms  

PubMed Central

Free and agarose-encapsulated pentachlorophenol (PCP)-degrading Sphingomonas sp. isolates UG25 and UG30 were compared to Sphingomonas chlorophenolica ATCC 39723 with respect to the ability to degrade PCP. Pretreatment of the UG25 and UG30 strains with 50 ?g of PCP per ml enabled the cells to subsequently degrade higher levels of this environmental pollutant. Similar treatment of ATCC 39723 cells had no effect on the level of PCP degraded by this strain. Phosphorus-31 nuclear magnetic resonance spectra of agarose-immobilized strains UG25 and UG30 grown in the absence of PCP showed that there was marked deenergization of the cells upon exposure to a nonlethal concentration of PCP (120 ?g/ml). For example, no transmembrane pH gradient was observed, and the ATP levels were lower than the levels obtained in the absence of PCP. The transmembrane pH gradient and ATP levels were restored once the immobilized cells had almost completely degraded the PCP in the perfusion medium. PCP-pretreated cells, on the other hand, maintained their transmembrane pH gradient and ATP levels even in the presence of high levels of PCP. The ability of PCP-pretreated strain UG25 and UG30 cells to remain energized in the presence of PCP was shown to correlate with an altered membrane phospholipid profile; these cells had a higher concentration of cardiolipin than cells cultured in the absence of PCP. Strain ATCC 39723, which did not degrade higher levels of PCP after PCP pretreatment, did not show this response. PMID:11472931

Lohmeier-Vogel, Elke M.; Leung, Kam T.; Lee, Hung; Trevors, Jack T.; Vogel, Hans J.

2001-01-01

22

Effect of Cyclosporine on Hepatic Energy Status and on Fructose Metabolism after Portacaval Shunt in Dog as Monitored by Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy in Vivo  

PubMed Central

The effect of cyclosporin A on the hepatic energy status and intracellular pH of the liver and its response to a fructose challenge has been investigated using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy in dogs. Three experimental groups were studied: (a) control dogs (n = 5), (b) dogs 4 days after the creation of an end-to-side portacaval shunt (n = 5), and (c) dogs 4 days after portacaval shunt and continuous infusion of cyclosporin A (4 mg/kg/day) by way of the left portal vein (portacaval shunt plus cyclosporin A, n = 5). The phosphorus-31 nuclear magnetic resonance spectra were obtained at 81 MHz using a Bruker BIOSPEC II 4.7-tesla nuclear magnetic resonance system equipped with a 40-cm horizontal bore superconducting solenoid. The phosphomonoesters (p < 0.01), inorganic phosphate and ATP levels (p < 0.05) were decreased significantly in portacaval shunt–treated and in portacaval shunt-plus-cyclosporin A–treated dogs compared with unshunted control dogs. After a fructose challenge (750 mg/kg body wt, intravenously), fructose-1-phosphate metabolism was reduced in portacaval shunt–treated dogs compared with either the normal or portacaval shunt-plus-cyclosporin A–treated dogs (p < 0.05). Both portacaval shunt– and portacaval shunt-plus-cyclosporin A–treated dogs demonstrated a reduced decline in ATP levels after fructose infusion when compared with the controls (p < 0.05). Immediately after the fructose challenge, the intracellular pH decreased from 7.30 ± 0.03 to 7.00 ± 0.05 in all animals (p < 0.01) and then gradually returned to normal over 60 min. These data, obtained in vivo using phosphorus-31 nuclear magnetic resonance spectroscopy of the liver after a portacaval shunt, suggest that: (a) the energy status of the liver is reduced in dogs with a portacaval shunt compared with that of normal controls and (b) cyclosporin A treatment ameliorates the reduction in hepatic metabolism normally observed after a fructose challenge to the liver with a portacaval shunt. PMID:2010174

Rossaro, Lorenzo; Mazzaferro, Vincenzo; Scotti-Foglieni, Carlo L.; Williams, Donald S.; Simplaceanu, Elena; Simplaceanu, Virgil; Francavilla, Antonio; Starzl, Thomas E.; Ho, Chien; Van Thiel, David H.

2010-01-01

23

Absolute concentration determination of phosphorus metabolites in the Langendorff-perfused rabbit heart by phosphorus-31 nuclear magnetic resonance  

SciTech Connect

The concentrations of mobile high energy phosphorus metabolites and intracellular pH of Langendorff-perfused rabbit heart have been determined under control and reduced flow conditions. Absolute concentration determination was accomplished by Lorentzian lineshape analysis after development of hexachlorocyclotriphosphazene as an external intensity standard. Hearts were demonstrated to be biochemically and physiologically competent during control perfusion periods and compromised during reduced flow conditions by independent hemodynamic and metabolic measurements coincident with the NMR experiment. Reduction in perfusate flow from 20 mL/min to 5.0 mL/min (25% flow) or 2.5 mL/min (12.5% flow) demonstrated a fall in phosphocreatine and adenosine triphosphate concentrations, a rise in cytosolic inorganic phosphate concentrations, and drops in pH. Subsequent recovery upon reflow was observed. The derived values for the free concentration of ADP were very close to the reported values of the Michaelis constant for respiratory stimulation, implicating a regulatory role for this molecule in cellular respiration. Strong evidence that the creating kinase reaction was in equilibrium in the 25% flow study was seen. The NMR observable correlated closely with myocardial performance and biochemical indices of metabolic function, and supported the use of phosphocreatine as an indicator of current metabolic integrity.

Gard, J.K.

1984-01-01

24

Protective effect of pretreatment with the calcium antagonist anipamil on the ischemic-reperfused rat myocardium: a phosphorus-31 nuclear magnetic resonance study  

SciTech Connect

To assess whether the prophylactic administration of anipamil, a new calcium antagonist, protects the heart against the effects of ischemia and reperfusion, rats were injected intraperitoneally twice daily for 5 days with 5 mg/kg body weight of this drug. The heart was then isolated and perfused by the Langendorff technique. Phosphorus-31 nuclear magnetic resonance spectroscopy was used to monitor myocardial energy metabolism and intracellular pH during control perfusion and 30 min of total ischemia (37/sup 0/C), followed by 30 min of reperfusion. Pretreatment with anipamil altered neither left ventricular developed pressure under normoxic conditions nor the rate and extent of depletion of adenosine triphosphate (ATP) and creatine phosphate during ischemia. Intracellular acidification, however, was attenuated. On reperfusion, hearts from anipamil-pretreated animals recovered significantly better than untreated hearts with respect to replenishment of ATP and creatine phosphate stores, restitution of low levels of intracellular inorganic phosphate and recovery of left ventricular function and coronary flow. Intracellular pH recovered rapidly to preischemic levels, whereas in untreated hearts a complex intracellular inorganic phosphate peak indicated the existence of areas of different pH within the myocardium. It is concluded that anipamil pretreatment protects the heart against some of the deleterious effects of ischemia and reperfusion. Because this protection occurred in the absence of a negative inotropic effect during normoxia, it cannot be attributed to an energy-sparing effect during ischemia. Therefore, alternative mechanisms of action are to be considered.

Kirkels, J.H.; Ruigrok, T.J.; Van Echteld, C.J.; Meijler, F.L.

1988-05-01

25

NMR Spectroscopy  

NSDL National Science Digital Library

Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. These questions pertain to Nuclear magnetic resonance (NMR) spectroscopy and include topics such as: Chemical Shift, Proton NMR, and Carbon NMR.

Reich, Ieva

26

Comparison of Phosphorus Forms in Wet and Dried Animal Manures by Solution Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy and Enzymatic Hydrolysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both enzymatic hydrolysis and solution 31P nuclear magnetic resonance (NMR) spectroscopy have been used to characterize P compounds in animal manures. However, no comparison of the two methods has been reported in the literature. In this study, we compared P compounds in dairy and poultry manures i...

27

Strategies for the uses of lanthanide NMR shift probes in the determination of protein structure in solutio. Application to the EF calcium binding site of carp parvalbumin.  

PubMed Central

The homologous sequences observed for many calcium binding proteins such as parvalbumin, troponin C, the myosin light chains, and calmodulin has lead to the hypothesis that these proteins have homologous structures at the level of their calcium binding sites. This paper discusses the development of a nuclear magnetic resonance (NMR) technique which will enable us to test this structural hypothesis in solution. The technique involves the substitution of a paramagnetic lanthanide ion for the calcium ion which results in lanthanide induced shifts and broadening in the 1H NMR spectrum of the protein. These shifts are sensitive monitors of the precise geometrical orientation of each proton nucleus relative to the metal. The values of several parameters in the equation relating the NMR shifts to the structure are however known as priori. We have attempted to determine these parameters, the orientation and principal elements of the magnetic susceptibility tensor of the protein bound metal, by studying the lanthanide induced shifts for the protein parvalbumin whose structure has been determined by x-ray crystallographic techniques. The interaction of the lanthanide ytterbium with parvalbumin results in high resolution NMR spectra exhibiting a series of resonances with shifts spread over the range 32 to -19 ppm. The orientation and principal elements of the ytterbium magnetic susceptibility tensor have been determined using three assigned NMR resonances, the His-26 C2 and C4 protons and the amino terminal acetyl protons, and seven methyl groups; all with known geometry relative to the EF calcium binding site. The elucidation of these parameters has allowed us to compare the observed spectrum of the nuclei surrounding the EF calcium binding site of parvalbumin with that calculated from the x-ray structure. A significant number of the calculated shifts are larger than any of the observed shifts. We feel that a refinement of the x-ray based proton coordinates will be possible utilizing the geometric information contained in the lanthanide shifted NMR spectrum. PMID:7248448

Lee, L; Sykes, B D

1980-01-01

28

Kinetics of 1H --> 31P NMR cross-polarization in bone apatite and its mineral standards.  

PubMed

Kinetics of NMR cross-polarization (CP) from protons to phosphorus-31 nuclei was studied in the following samples: mineral of whole human bone, apatite prepared from bone, natural brushite, synthetic hydroxyapatite (hydrated and calcined), and synthetic carbonatoapatite of type B with 9 wt% of CO(3) (2-). In order to avoid an effect of magic angle spinning on CP and relaxation, the experiments were carried out on static samples. Parameters of the CP kinetics were discussed for trabecular and cortical bone tissue from adult subjects in comparison to the synthetic mineral standards. It was found that carbonatoapatite shows similar CP behavior to the bone mineral. Both materials undergo two-component CP kinetics. The fast-relaxing classical component is from the surface of apatite crystals and the slow-relaxing nonclassical component comes from the crystal interior. The components have been unambiguously assigned using inverse CP from phosphorus-31 to protons. The study provides information on a structured water layer, which covers crystal surface of carbonato- and bone apatite. The layer encompasses ca 40% of apatite phosphorus and its thickness is more than ca 2 nm. PMID:18306247

Kaflak, Agnieszka; Kolodziejski, Waclaw

2008-04-01

29

NMR Spectroscopy  

NSDL National Science Digital Library

This site contains web-based programs that allow the user to predict chemical shifts, spin-spin coupling patterns and NMR line shapes affected by dynamic chemical exchange. This site will be most useful for students with a good background in the fundamentals of NMR theory.

Shattuck, Thomas W.

30

Quantitative NMR  

NSDL National Science Digital Library

This site features a learning module focused on principles and practice of NMR for quantitative analysis, an application less commonly associated with the technique than is structure determination. Links to simulation packages are included.

Korir, Albert K.

31

NMR Animations  

NSDL National Science Digital Library

This site features animated tutorials on NMR with sufficient depth to be useful to the non NMR savvy. The animations are accompanied by short descriptions so that the processes displayed can be understood by the viewer. This site goes beyond just showing precession. There are nice animations showing the effect of different pulses, including composite pulses on the magnetization, the effects of magnetic gradient pulses to measure diffusion and do coherence pathway selection.

32

NMR tutorial  

NSDL National Science Digital Library

This site provides an entry-level introduction to NMR in a text and figures format. The site also contains example structure elucidation problems using NMR, IR and MS data complete with hints and answers. Although the molecules included are somewhat simple, the examples do a good job of illustrating the structure elucidation process. The site also has data for several more complex structure determination problems.

Bogdal, Dariusz

33

NMR imaging  

SciTech Connect

Since hydrogen is the most abundant element in all living organisms, proton NMR lends itself well as a method of investigation in biology and medicine. NMR imaging has some special advantages as a diagnostic tool: no ionizing radiation is used, it is noninvasive; it provides a safer means of imaging than the use of x-rays, gamma rays, positrons, or heavy ions. In contrast with ultrasound, the radiation penetrates the bony structures without attenuation. In additional to morphological information, NMR imaging provides additional diagnostic insights through relaxation parameters, which are not available from other imaging methods. In the decade since the first primitive NMR images were obtained, the quality of images now obtained approaches those from CT x-ray scanners. Prototype instruments are being constructed for clinical evaluation and the first whole-body scanners are beginning to appear on the market at costs comparable to CT scanners. Primary differences in equipment for conventional NMR and NMR imaging are the much larger aperture magnets that are required for the examination of human subjects and the addition of coils to generate field gradients and facilities for manipulating the gradients. Early results from clinical trials in many parts of the world are encouraging, and in a few years, the usefuleness of this modality of medical imaging to the medical profession in diagnosis and treatment of disease will be defined. 10 figures.

Andrew, E.R.

1983-04-01

34

User Guide: Liquids NMR  

E-print Network

User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C Software Pub. No. 01-999161-00, Rev. B0801 #12;User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C Software Pub. No. 01-999161-00, Rev. B0801 #12;User Guide: Liquids NMR Varian NMR Spectrometer Systems With VNMR 6.1C

Zhou, Pei

35

1. An N.M.R. Study of Keto-Enol Tautomerism in -Diketones. Allen, G. and Dwek, R.A. (1966) J. Chem. Soc. B, 161-163.  

E-print Network

Interaction and its Application to Dynamic Polarisation Results of Phosphorus-31 Nuclei. Dwek, R.A., Richards.Phys., 6, 529-532. 5. Dynamic Polarisation of Phosphorus-31 Nuclei at 12,500 Gauss. Dwek, R.A. and Richards.Rev.Phys.Chem. 18, 99-124. 11. Scalar interactions in phosphorus-31 systems as studied by dynamic nuclear

36

C NMR Spectra C NMR Spectra  

E-print Network

S16 1 H and 13 C NMR Spectra (see p S3) Me N-i-Pr #12;S17 1 H and 13 C NMR Spectra (see p S3) Me NBn #12;S18 1 H and 13 C NMR Spectra (see p S4) NBn #12;S19 1 H and 13 C NMR Spectra (see p S4) NBn Me Me Me #12;S20 1 H and 13 C NMR Spectra (see p S4) N-n-Bu Me Me Me #12;S21 1 H and 13 C NMR Spectra

Collum, David B.

37

In vivo sup 31 P-NMR spectroscopy of chronically stimulated canine skeletal muscle  

SciTech Connect

Chronic stimulation converts skeletal muscle of mixed fiber type to a uniform muscle made up of type I, fatigue-resistant fibers. Here, the bioenergetic correlates of fatigue resistance in conditioned canine latissimus dorsi are assessed with in vivo phosphorus-31 nuclear magnetic resonance ({sup 31}P-NMR) spectroscopy. After chronic electrical stimulation, five dogs underwent {sup 31}P-NMR spectroscopic and isometric tension measurements on conditioned and contralateral control muscle during stimulation for 200, 300, 500, and 800 ms of an 1,100-ms duty cycle. With stimulation, phosphocreatine (PCr) fell proportional to the degree of stimulation in both conditioned and control muscle but fell significantly less in conditioned muscle at all the least intense stimulation period (200 ms). Isometric tension, expressed as a tension time index per gram muscle, was significantly greater in the conditioned muscle at the two longest stimulation periods. The overall small change in PCr and the lack of a plateau in tension observed in the conditioned muscle are similar to that seen in cardiac muscle during increased energy demand. This study indicates that the conditioned muscle's markedly enhanced resistance to fatigue is in part the result of its increased capacity for oxidative phosphorylation.

Clark, B.J. III; McCully, A.K.; Subramanian, H.V.; Hammond, R.L.; Salmons, S.; Chance, B.; Stephenson, L.W. (Children's Hospital of Philadelphia, Harrison (USA) Univ. of Pennsylvania School of Medicine, Philadelphia (USA) Univ. of Birmingham (England))

1988-02-01

38

Interaction of the Saccharomyces cerevisiae. alpha. -factor with phospholipid vesicles as revealed by proton and phosphorus NMR  

SciTech Connect

Proton and phosphorus-31 nuclear magnetic resonance ({sup 1}H and {sup 31}P NMR) studies of the interaction between a tridecapeptide pheromone, the {alpha}-factor of Saccharomyces cerevisiae, and sonicated lipid vesicles are reported. {sup 31}P NMR studies demonstrate that there is interaction of the peptide with the phosphorus headgroups, and quasielastic light scattering (QLS) studies indicate that lipid vesicles increase in size upon addition of peptide. Previous solution (aqueous and DMSO) studies from this laboratory indicate that {alpha}-factor is highly flexible with only one long-lived identifiable structural feature, a type II {beta}-turn spanning the central portion of the peptide. Two-dimensional (2D) {sup 1}H nuclear Overhauser effect spectroscopy (NOESY) studies demonstrate a marked ordering of the peptide upon interaction with lipid, suggesting a compact N-terminus, in addition to a stabilized {beta}-turn. In contrast to these results in both solution and lipid environment, Wakamatsu et al. proposed a lipid environment conformation, on the basis of one-dimensional transferred NOE studies in D{sub 2}O, which does not include the {beta}-turn.

Jelicks, L.A.; Broido, M.S.; Becker, J.M.; Naider, F.R. (City Univ. of New York, NY (USA))

1989-05-16

39

Fundamentals of NMR  

NSDL National Science Digital Library

This e-text presents an introduction to the fundamentals of NMR covering magnetic resonance, pulsed NMR, relaxation, chemical shift, spin-spin coupling, the nuclear Overhauser effect and chemical exchange. The document may be downloaded in PDF format.

James, Thomas L.

40

NMR analysis of biodiesel  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

41

31P-NMR SPECTROSCOPY OF RAT LIVER DURING SIMPLE STORAGE OR CONTINUOUS HYPOTHERMIC PERFUSION1  

PubMed Central

SUMMARY The ATP content and intracellular pH (pHi)3 of isolated rat liver before, during, and after cold preservation in either UW-lactobionate (UW, n=10) or Euro-Collins (EC, n=8) solutions were monitored using phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy. The 31P-NMR spectra were obtained on a 4.7-Tesla system operating at 81 MHz. Fructose metabolism, liver enzyme release, O2 consumption, and rat survival after liver transplantation were also evaluated. During simple cold storage (SCS), the ATP level declined to undetectable levels with both preservation solutions while the pHi declined to approximately 7.0. In contrast, during continuous hypothermic perfusion (CHP), hepatic ATP levels remained measurable during the 24-hour EC preservation and actually increased significantly (p>0.01) during UW preservation. After reperfusion at 37°C with Krebs-lactate, the SCS livers treated with EC differed significantly from the UW livers in terms of their ATP and pHi as well as their response to a fructose challenge. In contrast, livers undergoing CHP demonstrated similar behaviors with both solutions. These results demonstrate an increase in the hepatic ATP content during CHP which occurs with UW but is not seen with EC. On the other hand, only livers that were simply stored with UW achieved significant survival after transplant, while CHP livers were affected by vascular damage as demonstrated by fatal thrombosis after transplant. These data suggest that ATP content is not the only determinant of good liver function although a system of hypothermic perfusion might further improve liver preservation efficacy should injury to vascular endothelium be avoided. PMID:1402332

Rossaro, Lorenzo; Murase, Noriko; Caldwell, Cary; Farghali, Hassan; Casavilla, Adrian; Starzl, Thomas E.; Ho, Chien; Van Thiel, David H.

2010-01-01

42

Understanding NMR Spectroscopy  

NSDL National Science Digital Library

This site provides links to a series of PDF files that represent chapters of an e-text on the basics of NMR. While many other textbooks on NMR are available, the chief merit of this one is that it has a nice chapter on the NMR instrumentation (ch. 5) which should be accessible to undergraduates. The text also provides a relatively mathematics-free or maybe more accurately Dirac bracket notation-free introduction to 1-D and 2-D (COSY and NOESY) experiments that would be appreciated by advanced undergraduates or beginning graduate students involved in undergraduate research experiences using NMR.

Keeler, James

43

NMR Spectroscopy - Theory  

NSDL National Science Digital Library

This web site begins with a simple quantum description of NMR and proceeds to introduce resonance absorption, relaxation, chemical shifts, and scalar couplings. This site will be useful for advanced undergraduate students needing a description of NMR that is more detailed than that given in most introductory Organic texts.

Lord, J.R.

44

Lectures on pulsed NMR  

SciTech Connect

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

Pines, A.

1988-08-01

45

Lectures on pulsed NMR  

SciTech Connect

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

Pines, A.

1986-09-01

46

NMR logging apparatus  

DOEpatents

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

Walsh, David O; Turner, Peter

2014-05-27

47

Basics of NMR  

NSDL National Science Digital Library

Dr. Joseph Hornak of the Rochester Institute of Technology presents this high quality hypertextbook for in-depth coverage of the physics and technique behind Nuclear Magnetic Resonance (NMR) (For Dr. Hornak's Basics of MRI, see the August 4, 1999 Scout Report for Science & Engineering). The material is presented in a detailed and clear manner without over simplifying the concepts. Chapters include "The Mathematics of NMR," "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Pulse Sequences," and much more. A chapter on "NMR Hardware" offers an overview of components (like the superconducting magnet and various coils) used in most NMR systems. The "Practical Considerations" chapter emphasizes spectroscopic techniques. With the screen split into two separate frames, explanatory graphics can be viewed alongside the text. A glossary and a list of symbols are also included in this carefully produced textbook.

Hornak, Joseph P.

48

Pressure effect of the /sup 1/H NMR spectra of organic compounds in the presence of lanthanide shift reagents. A formally associative process characterized by volume expansion  

SciTech Connect

Following the successful application of hydrostatic pressure in mechanistic investigations of organic reactions, chemists have launched a vigorous effort to apply this tool to substitution reactions of coordination compounds. The authors began to study pressure effects in the NMR spectra of keton-lanthanide combination with the hope that the increase shifts anticipated might enhance the utility of the method, perhaps even expand its applicability to new classes of compounds. 5-Phenyl- and 5-tert-butyladamantan-2-one, piperidine, tetrahydrofuran, and cyclopentanol exhibited pressure-reduced lanthanide-induced shifts with Eu(fod)/sub 3/; Yb(fob)/sub 3/ and the shielding reagent Pr(fod)/sub 3/ showed the same effect with adamantanone. Solvent variations (CD/sub 2/Cl/sub 2/, CCl/sub 4/) caused minor changes in the magnitude of these shifts but did not reverse any. With the objective of learning whether these effects are due to a suppressed equilibrium population or to a reduction in the bound shift of the complex, they measured the spectra for a series or equimolar solutions of adamantanone and Eu(fod)/sub 3/ in CDCl/sub 3/ and used the Bouquant-Chuche equation to calculate both. Reasonable agreement with known atmosphere pressure data was obtained.

Schulman, E.M.; Cheung, C.K.; Merbach, A.E.; Yamada, H.; le Noble, W.J.

1987-11-11

49

Catalytic mechanism of ?-phosphate attack in dUTPase is revealed by X-ray crystallographic snapshots of distinct intermediates, 31P-NMR spectroscopy and reaction path modelling  

PubMed Central

Enzymatic synthesis and hydrolysis of nucleoside phosphate compounds play a key role in various biological pathways, like signal transduction, DNA synthesis and metabolism. Although these processes have been studied extensively, numerous key issues regarding the chemical pathway and atomic movements remain open for many enzymatic reactions. Here, using the Mason–Pfizer monkey retrovirus dUTPase, we study the dUTPase-catalyzed hydrolysis of dUTP, an incorrect DNA building block, to elaborate the mechanistic details at high resolution. Combining mass spectrometry analysis of the dUTPase-catalyzed reaction carried out in and quantum mechanics/molecular mechanics (QM/MM) simulation, we show that the nucleophilic attack occurs at the ?-phosphate site. Phosphorus-31 NMR spectroscopy (31P-NMR) analysis confirms the site of attack and shows the capability of dUTPase to cleave the dUTP analogue ?,?-imido-dUTP, containing the imido linkage usually regarded to be non-hydrolyzable. We present numerous X-ray crystal structures of distinct dUTPase and nucleoside phosphate complexes, which report on the progress of the chemical reaction along the reaction coordinate. The presently used combination of diverse structural methods reveals details of the nucleophilic attack and identifies a novel enzyme–product complex structure. PMID:23982515

Barabás, Orsolya; Németh, Veronika; Bodor, Andrea; Perczel, András; Rosta, Edina; Kele, Zoltán; Zagyva, Imre; Szabadka, Zoltán; Grolmusz, Vince I.; Wilmanns, Matthias; Vértessy, Beáta G.

2013-01-01

50

Modern NMR Spectroscopy.  

ERIC Educational Resources Information Center

Discusses direct chemical information that can be obtained from modern nuclear magnetic resonance (NMR) methods, concentrating on the types of problems that can be solved. Shows how selected methods provide information about polymers, bipolymers, biochemistry, small organic molecules, inorganic compounds, and compounds oriented in a magnetic…

Jelinski, Lynn W.

1984-01-01

51

NMR Studies of Peroxidases.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. Peroxidases are a haem-containing group of enzymes with a wide diversity of function within biological systems. While a common characteristic is the ability to catalyse the conversion of hydrogen peroxide to water, it is the accompanying processes of hormone synthesis and degradation which have generated such a high level of interest. However, information at the molecular level is limited to a single well-resolved crystal structure, that of yeast cytochrome c peroxidase. This thesis presents a strategy for the investigation of peroxidase structure and function based on proton nuclear magnetic resonance spectroscopy, a technique which has the ability to address aspects of both protein structure and protein dynamics in solution. The application of one- and two-dimensional NMR techniques has been developed in the context of plant peroxidases, notably the isoenzyme HRP-C derived from the horseradish root. Characterisation of the proton NMR spectra of HRP -C in resting and ligated states provided new information enabling the structure of the binding site for aromatic donor molecules, such as indole-3-propionic, ferulic and benzhydroxamic acids, to be resolved. In order to overcome difficulties encountered with a protein of the complexity of peroxidase, additional information was obtained from chemical shift parameters and the use of peroxidase variants produced by site-directed mutagenesis. A comparative study using NMR spectroscopy was undertaken for wild-type recombinant HRP-C expressed in Escherichia coli, and two protein variants with substitutions made to residues located on the distal side of the haem pocket, Phe41 to Val and Arg38 to Lys. NMR analyses of a plant peroxidase from barley grains and the fungal peroxidase from Coprinus cinereus were also successful using methods conceived with HRP-C. Examination of three specifically constructed recombinant protein variants of C. cinereus peroxidase was essential in confirming the identity of residues participating in the aromatic donor molecule binding site of peroxidases.

Veitch, Nigel Charles

52

Soils, Pores, and NMR  

NASA Astrophysics Data System (ADS)

Within Cluster A, Partial Project A1, the pore space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the pore geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 < 5 ms. Moreover, the dependence of the relaxation rate on magnetic field strength allows the identification of 2D diffusion at the interfaces as the mechanism which governs the relaxation process (Pohlmeier et al. 2009). T2 relaxation curves are frequently measured for the rapid characterization of soils by means of the CPMG echo train. Basically, they contain the same information about the pore systems like T1 curves, since mostly the overall relaxation is dominated by surface relaxivity and the surface/volume ratio of the pores. However, one must be aware that T2 relaxation is additionally affected by diffusion in internal gradients, and this can be overcome by using sufficiently short echo times and low magnetic fields (Stingaciu et al. 2009). Second, the logic continuation of conventional relaxation measurements is the 2-dimensional experiment, where prior to the final detection of the CPMG echo train an encoding period is applied. This can be T1-encoding by an inversion pulse, or T2 encoding by a sequence of 90 and 180° pulses. During the following evolution time the separately encoded signals can mix and this reveals information about the connectivity of the pore system. Examples are given for T1-T2 correlation of some soil samples (Haber-Pohlmeier et al. 2010). Third, relaxometric information forms the basis of understanding magnetic resonance imaging (MRI) results. The general difficulty of imaging in soils are the inherent fast T2 relaxation times due to i) the small pore sizes, ii) presence of paramagnetic ions in the solid matrix, and iii) diffusion in internal gradients. The last point is important, since echo times can not set shorter than about 1ms for imaging purposes. The way out is either the usage of low fields for imaging in soils or special ultra-short pulse sequences, which do not create echoes. In this presentation we will give examples on conventional imaging of macropore fluxes in soil cores (Haber-Pohlmeier et al. 2010), and the combination with relaxometric imaging, as well as the advantages and drawbacks of low-field and ultra-fast pulse imaging. Also first results on the imaging of soil columns measured by SIP in Project A3 are given. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Waterflow Monitored by Tracer Transport in Natural Porous Media Using MRI." Vadose Zone J.: submitted. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Relaxation in a Natural soil: Comparison of Relaxometric Imaging, T1 - T2 Correlation and Fast-Field Cycling NMR." The Open Magnetic Resonance Journal: in print. Pohlmeier, A., S. Haber-Pohlmeier, et al. (2009). "A Fast Field Cycling NMR Relaxometry Study of Natural Soils." Vadose Zone J. 8: 735-742. Stingaciu, L. R., A. Pohlmeier, et al. (2009). "Characterization of unsaturated porous media by high-field and low-field NMR relaxometry." Water Resources Research 45: W08412

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

2010-05-01

53

NMR spectroscopic studies of "titanocene"  

E-print Network

NMR SPECTROSCOPIC STUDIES OF "TITANOCENE" A Thea is by DONALD FLOYD BIRKELBACH Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1971 Ma)or Sub...)cot: Chemistry NMR SPECTROSCOPIC STUDIES OF "TITANOCENE" A Thesis by DONALD FLOYD BIRKELBACH Approved as to style and content by: (C ai"iman of Committee) (Head of Department) (Member) (Member) (Member) (Memb er) (Member) May 1971 ABSTRACT NMR...

Birkelbach, Donald Floyd

1971-01-01

54

NMR Spectroscopy of Azo Dyes  

Microsoft Academic Search

The known NMR spectroscopy data on different types of synthetic azo and polyazo dyes, including metal complexes, are correlated. The fundamentally new opportunities in the NMR spectroscopy of 1H, 13C, and 15N nuclei in solving problems of structural chemistry in this field of industrial chemistry are demonstrated. The bibliography includes 124 references.

L A Fedorov

1988-01-01

55

NMR Spectroscopy of Azo Dyes  

NASA Astrophysics Data System (ADS)

The known NMR spectroscopy data on different types of synthetic azo and polyazo dyes, including metal complexes, are correlated. The fundamentally new opportunities in the NMR spectroscopy of 1H, 13C, and 15N nuclei in solving problems of structural chemistry in this field of industrial chemistry are demonstrated. The bibliography includes 124 references.

Fedorov, L. A.

1988-10-01

56

THz Dynamic Nuclear Polarization NMR  

PubMed Central

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The enhancement in NMR sensitivity can amount to a factor of well above 100, enabling faster data acquisition and greatly improved NMR measurements. With the increasing magnetic fields (up to 23 T) used in NMR research, the required frequency for DNP falls into the THz band (140–600 GHz). Gyrotrons have been developed to meet the demanding specifications for DNP NMR, including power levels of tens of watts; frequency stability of a few megahertz; and power stability of 1% over runs that last for several days to weeks. Continuous gyrotron frequency tuning of over 1 GHz has also been demonstrated. The complete DNP NMR system must include a low loss transmission line; an optimized antenna; and a holder for efficient coupling of the THz radiation to the sample. This paper describes the DNP NMR process and illustrates the THz systems needed for this demanding spectroscopic application. THz DNP NMR is a rapidly developing, exciting area of THz science and technology. PMID:24639915

Nanni, Emilio A.; Barnes, Alexander B.; Griffin, Robert G.; Temkin, Richard J.

2013-01-01

57

Two-dimensional NMR spectroscopy  

SciTech Connect

Written for chemists and biochemists who are not NMR spectroscopists, but who wish to use the new techniques of two-dimensional NMR spectroscopy, this book brings together for the first time much of the practical and experimental data needed. It also serves as information source for industrial, academic, and graduate student researchers who already use NMR spectroscopy, but not yet in two dimensions. The authors describe the use of 2-D NMR in a wide variety of chemical and biochemical fields, among them peptides, steroids, oligo- and poly-saccharides, nucleic acids, natural products (including terpenoids, alkaloids, and coal-derived heterocyclics), and organic synthetic intermediates. They consider throughout the book both the advantages and limitations of using 2-D NMR.

Croasmun, W.R.; Carlson, R.M.K.

1987-01-01

58

NMR Sample Policy Version: 20 Jul 2006  

E-print Network

NMR Sample Policy Version: 20 Jul 2006 Task: NMR Sample Preparation Equipment Used: Centrifuge, p Assessment NMR002 `Protein NMR Sample Preparation' on the Cancer Studies COSHH database covers a number bacteria. 3. Low: Use of any biological hazard is discouraged and must follow all COSHH regulations. Some

Birmingham, University of

59

THz Dynamic Nuclear Polarization NMR  

E-print Network

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

Nanni, Emilio Alessandro

60

Optical pumping and xenon NMR  

SciTech Connect

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

Raftery, M.D.

1991-11-01

61

Optical pumping and xenon NMR  

SciTech Connect

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

Raftery, M.D.

1991-11-01

62

Multispectral Analysis of NMR Imagery  

NASA Technical Reports Server (NTRS)

Conference paper discusses initial efforts to adapt multispectral satellite-image analysis to nuclear magnetic resonance (NMR) scans of human body. Flexibility of these techniques makes it possible to present NMR data in variety of formats, including pseudocolor composite images of pathological internal features. Techniques do not have to be greatly modified from form in which used to produce satellite maps of such Earth features as water, rock, or foliage.

Butterfield, R. L.; Vannier, M. W. And Associates; Jordan, D.

1985-01-01

63

NMR characterization of thin films  

DOEpatents

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

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

2010-06-15

64

NMR characterization of thin films  

DOEpatents

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

Gerald, II, Rex E. (Brookfield, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Homer Glen, IL); Diaz, Rocio (Chicago, IL); Vukovic, Lela (Westchester, IL)

2008-11-25

65

Polarization transfer NMR imaging  

DOEpatents

A nuclear magnetic resonance (NMR) image is obtained with spatial information modulated by chemical information. The modulation is obtained through polarization transfer from a first element representing the desired chemical, or functional, information, which is covalently bonded and spin-spin coupled with a second element effective to provide the imaging data. First and second rf pulses are provided at first and second frequencies for exciting the imaging and functional elements, with imaging gradients applied therebetween to spatially separate the nuclei response for imaging. The second rf pulse is applied at a time after the first pulse which is the inverse of the spin coupling constant to select the transfer element nuclei which are spin coupled to the functional element nuclei for imaging. In a particular application, compounds such as glucose, lactate, or lactose, can be labeled with .sup.13 C and metabolic processes involving the compounds can be imaged with the sensitivity of .sup.1 H and the selectivity of .sup.13 C.

Sillerud, Laurel O. (Los Alamos, NM); van Hulsteyn, David B. (Santa Fe, NM)

1990-01-01

66

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

SciTech Connect

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

Matwiyoff, N.A.

1983-01-01

67

NMR characterization of shocked quartz  

SciTech Connect

We have characterized experimentally and naturally-shocked quartz (both synthetic and natural samples) by solid state nuclear magnetic resonance (NMR) spectroscopy. Relaxation analysis of experimentally-shocked samples provides a means for quantitative characterization of the amorphous/disordered silica component NMR spectra demonstrate that magnetization in both the amorphous and crystalline components follows power-law behavior as a function of recycle time. This observation is consistent with the relaxation of nuclear spins by paramagnetic impurities. A fractal dimension can be extracted from the power-law exponent associated with each phase, and relative abundances can be extracted from integrated intensities of deconvolved peaks. NMR spectroscopy of naturally-shocked sandstone from Meteor Crater, Arizona (USA) led to the discovery of a new amorphous hydroxylated silica phase. Solid state NMR spectra of both experimentally and naturally shocked quartz were unexpectedly rich in microstructural information, especially when combined with relaxation analysis and cross-polarization studies. We suggest solid state NMR as a potentially useful tool for examining shock-induced microstructural changes in other inorganic compounds, with possible implications for shock processing of structural ceramics.

Boslough, M.B.; Cygan, R.T.; Assink, R.A. [Sandia National Labs., Albuquerque, NM (United States); Kirkpatrick, R.J. [Illinois Univ., Urbana, IL (United States)

1994-03-01

68

Push-through Direction Injectin NMR Automation  

EPA Science Inventory

Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

69

A SENSITIVE NMR THERMOMETER FOR MULTINUCLEI FT NMR  

EPA Science Inventory

A pernicious problem in multinuclei FT NMR is accurate measurement of sample temperature. This arises from several factors including widespread use of high-power decoupling, large sample tubes (with potentially large temperature gradients across the sample volume), and lack of su...

70

Application of 1H and 23Na magic angle spinning NMR spectroscopy to define the HRBC up-taking of MRI contrast agents  

NASA Astrophysics Data System (ADS)

The up-take of Gd(III) complexes of BOPTA, DTPA, DOTA, EDTP, HPDO3A, and DOTP in HRBC has been evaluated by measuring the lanthanide induced shift (LIS) produced by the corresponding dysprosium complexes (DC) on the MAS-NMR resonances of water protons and free sodium ions. These complexes are important in their use as MRI contrast agents (MRI-CA) in diagnostics. 1H and 23Na MAS-NMR spectra of HRBC suspension, collected at 9.395 T, show only one signal due to extra- and intra-cellular water (or sodium). In MAS spectra, the presence of DC in a cellular compartment produces the LIS of only the nuclei (water proton or sodium) in that cellular compartment and this LIS can be related to the DC concentrations (by the experimental curves of LIS vs. DC concentrations) collected in the physiological solution. To obtain correct results about LIS, the use of MAS technique is mandatory, because it guarantees the only the nuclei staying in the same cellular compartment where the LC is present show the LIS. In all the cases considered, the addition of the DC to HRBC (100% hematocrit) produced a shift of only the extra-cellular water (or sodium) signal and the gradient of concentration ( GC) between extra- and intra-cellular compartments resulted greater than 100:1, when calculated by means of sodium signals. These high values of GC are direct proofs that none of the tested dysprosium complexes crosses the HRBC membrane. Since the DC are iso-structural to the gadolinium complexes the corresponding gadolinium ones (MRI-CA) do not cross the HRBC membrane and, consequently, they are not up-taken in HRBC. The GC values calculated by means of water proton signals resulted much lower than those obtained by sodium signals. This proves that the choice of the isotope is a crucial step in order to use this method in the best way. In fact, GC value depends on the lowest detectable LIS which, in turn, depends on the nature of the LC (lanthanide complex) and the observed isotopes.

Calabi, Luisella; Paleari, Lino; Biondi, Luca; Linati, Laura; De Miranda, Mario; Ghelli, Stefano

2003-09-01

71

Solving structures by NMR Qinghua Wang  

E-print Network

Solving structures by NMR Qinghua Wang 1232B LGRT 545-3473; qwang@biochem.umass.edu #12;1946 Bloch Fourier transform NMR 1975 Jeener, Ernst 2D NMR 1985 Wüthrich first solution structure of a small protein reminders from last lecture 2. The problem of sequential assignment, and how it is solved 3. Calculating

Hardy, Jeanne

72

Petrophysical applications of NMR imaging  

Microsoft Academic Search

A system for obtaining high-resolution NMR images of oil field cores is described. Separate proton density and Tâ relaxation images are obtained to distinguish spatial variations of fluid-filled porosity and the physical nature of the pores. Results are presented for typical sandstones.

William P. Rothwell; H. J. Vinegar

1985-01-01

73

QUANTITATIVE 15N NMR SPECTROSCOPY  

EPA Science Inventory

Line intensities in 15N NMR spectra are strongly influenced by spin-lattice and spin-spin relaxation times, relaxation mechanisms and experimental conditions. Special care has to be taken in using 15N spectra for quantitative purposes. Quantitative aspects are discussed for the 1...

74

Computer Simulation of NMR Spectra.  

ERIC Educational Resources Information Center

Describes a PASCAL computer program which provides interactive analysis and display of high-resolution nuclear magnetic resonance (NMR) spectra from spin one-half nuclei using a hard-copy or monitor. Includes general and theoretical program descriptions, program capability, and examples of its use. (Source for program/documentation is included.)…

Ellison, A.

1983-01-01

75

C NMR Spectra (see p S10)  

E-print Network

S31 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 10 #12;S32 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 11 #12;S33 1 H and 13 C NMR Spectra (see p S11) NH-i-Pr n-Bu NH-i-Pr n-Bu 12 Me Me 13 #12;S34 1 H and 13 C NMR Spectra (see p S11)NH-i-Pr Me Ph 14 #12;S35 1 H and 13 C NMR Spectra (see p S11

Collum, David B.

76

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with {sup 13}C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed a delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

Zilm, K.W.

1992-05-27

77

ELISE NMR: experimental liquid sealing of NMR samples.  

PubMed

We present a simple, generally applicable approach to prevent sample evaporation when working at elevated temperatures in high resolution NMR. It consists of experimentally sealing the NMR sample by a second liquid (Experimental Liquid Sealing, ELISE). For aqueous samples, we identified the mineral oil commonly used in PCR application as the best candidate, because it contains only a very limited amount of water-soluble contaminants, is stable over time and heat resistant. The procedure does not interfere with shim settings, and is compatible with a wide variety of samples, including oligosaccharides and proteins. For chloroform samples, a simple drop of water allows to efficiently seal the sample, avoiding solvent evaporation even over lengthy time periods. PMID:16709462

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

2006-08-01

78

Microcoil NMR spectroscopy: a novel tool for biological high throughput NMR spectroscopy.  

PubMed

Microcoil NMR spectroscopy is based on the increase of coil sensitivity for smaller coil diameters (approximately 1/d). Microcoil NMR probes deliver a remarkable mass-based sensitivity increase (8- to 12-fold) when compared with commonly used 5-mm NMR probes. Although microcoil NMR probes are a well established analytical tool for small molecule liquid-state NMR spectroscopy, after spectroscopy only recently have microcoil NMR probes become available for biomolecular NMR spectroscopy. This chapter highlights differences between commercially available microcoil NMR probes suitable for biomolecular NMR spectroscopy. Furthermore, it provides practical guidance for the use of microcoil probes and shows direct applications for structural biology and structural genomics, such as optimal target screening and structure determination, among others. PMID:18542883

Hopson, Russell E; Peti, Wolfgang

2008-01-01

79

REDOR NMR for Drug Discovery  

PubMed Central

Rotational-Echo DOuble-Resonance (REDOR) NMR is a powerful and versatile solid-state NMR measurement that has been recruited to elucidate drug modes of action and to drive the design of new therapeutics. REDOR has been implemented to examine composition, structure, and dynamics in diverse macromolecular and whole-cell systems, including taxol-bound microtubules, enzyme-cofactor-inhibitor ternary complexes, and antibiotic-whole-cell complexes. The REDOR approach involves the integrated design of specific isotopic labeling strategies and the selection of appropriate REDOR experiments. By way of example, this digest illustrates the versatility of the REDOR approach, with an emphasis on the practical considerations of experimental design and data interpretation. PMID:24035486

Cegelski, Lynette

2014-01-01

80

NMR study of trialuminide intermetallics  

Microsoft Academic Search

We present a systematic study of the DO22-structure trialuminide intermetallic alloys using 27Al NMR spectroscopy. The quadrupole splittings, Knight shifts, and spin-lattice relaxation times on Al3Ti, Al3V, Al3Nb, and Al3Ta have been identified. Knight-shift tensors were isolated by observation of quadrupole satellite lines and fitting to the central-transition powder patterns. The results are associated with the local electronic density of

Chin-Shan Lue; Suchitra Chepin; James Chepin; Joseph H. Ross Jr.

1998-01-01

81

Scalable NMR spectroscopy with semiconductor chips  

PubMed Central

State-of-the-art NMR spectrometers using superconducting magnets have enabled, with their ultrafine spectral resolution, the determination of the structure of large molecules such as proteins, which is one of the most profound applications of modern NMR spectroscopy. Many chemical and biotechnological applications, however, involve only small-to-medium size molecules, for which the ultrafine resolution of the bulky, expensive, and high-maintenance NMR spectrometers is not required. For these applications, there is a critical need for portable, affordable, and low-maintenance NMR spectrometers to enable in-field, on-demand, or online applications (e.g., quality control, chemical reaction monitoring) and co-use of NMR with other analytical methods (e.g., chromatography, electrophoresis). As a critical step toward NMR spectrometer miniaturization, small permanent magnets with high field homogeneity have been developed. In contrast, NMR spectrometer electronics capable of modern multidimensional spectroscopy have thus far remained bulky. Complementing the magnet miniaturization, here we integrate the NMR spectrometer electronics into 4-mm2 silicon chips. Furthermore, we perform various multidimensional NMR spectroscopies by operating these spectrometer electronics chips together with a compact permanent magnet. This combination of the spectrometer-electronics-on-a-chip with a permanent magnet represents a useful step toward miniaturization of the overall NMR spectrometer into a portable platform. PMID:25092330

Ha, Dongwan; Paulsen, Jeffrey; Sun, Nan; Song, Yi-Qiao; Ham, Donhee

2014-01-01

82

Scalable NMR spectroscopy with semiconductor chips.  

PubMed

State-of-the-art NMR spectrometers using superconducting magnets have enabled, with their ultrafine spectral resolution, the determination of the structure of large molecules such as proteins, which is one of the most profound applications of modern NMR spectroscopy. Many chemical and biotechnological applications, however, involve only small-to-medium size molecules, for which the ultrafine resolution of the bulky, expensive, and high-maintenance NMR spectrometers is not required. For these applications, there is a critical need for portable, affordable, and low-maintenance NMR spectrometers to enable in-field, on-demand, or online applications (e.g., quality control, chemical reaction monitoring) and co-use of NMR with other analytical methods (e.g., chromatography, electrophoresis). As a critical step toward NMR spectrometer miniaturization, small permanent magnets with high field homogeneity have been developed. In contrast, NMR spectrometer electronics capable of modern multidimensional spectroscopy have thus far remained bulky. Complementing the magnet miniaturization, here we integrate the NMR spectrometer electronics into 4-mm(2) silicon chips. Furthermore, we perform various multidimensional NMR spectroscopies by operating these spectrometer electronics chips together with a compact permanent magnet. This combination of the spectrometer-electronics-on-a-chip with a permanent magnet represents a useful step toward miniaturization of the overall NMR spectrometer into a portable platform. PMID:25092330

Ha, Dongwan; Paulsen, Jeffrey; Sun, Nan; Song, Yi-Qiao; Ham, Donhee

2014-08-19

83

Advanced NMR technology for bioscience and biotechnology  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). NMR plays critical roles in bioscience and biotechnology in both imaging and structure determination. NMR is limited, however, by the inherent low sensitivity of the NMR experiment and the demands for spectral resolution required to study biomolecules. The authors addressed both of these issues by working on the development of NMR force microscopy for molecular imaging, and high field NMR with isotope labeling to overcome limitations in the size of biomolecules that can be studied using NMR. A novel rf coil design for NMR force microscopy was developed that increases the limits of sensitivity in magnetic resonance detection for imaging, and the authors demonstrated sub-surface spatial imaging capabilities. The authors also made advances in the miniaturization of two critical NMR force microscope components. They completed high field NMR and isotope labeling studies of a muscle protein complex which is responsible for regulating muscle contraction and is too large for study using conventional NMR approaches.

Hammel, P.C.; Hernandez, G.; Trewhella, J.; Unkefer, C.J. [Los Alamos National Lab., NM (US); Boumenthal, D.K. [Univ. of Utah, Salt Lake City, UT (US); Kennedy, M.A. [Pacific Northwest National Lab., Richland, WA (US); Moore, G.J. [Wayne State Univ., Detroit, MI (US)

1998-11-01

84

Hyperpolarized 131Xe NMR spectroscopy  

PubMed Central

Hyperpolarized (hp) 131Xe with up to 2.2% spin polarization (i.e., 5000-fold signal enhancement at 9.4 T) was obtained after separation from the rubidium vapor of the spin-exchange optical pumping (SEOP) process. The SEOP was applied for several minutes in a stopped-flow mode, and the fast, quadrupolar-driven T1 relaxation of this spin I = 3/2 noble gas isotope required a rapid subsequent rubidium removal and swift transfer into the high magnetic field region for NMR detection. Because of the xenon density dependent 131Xe quadrupolar relaxation in the gas phase, the SEOP polarization build-up exhibits an even more pronounced dependence on xenon partial pressure than that observed in 129Xe SEOP. 131Xe is the only stable noble gas isotope with a positive gyromagnetic ratio and shows therefore a different relative phase between hp signal and thermal signal compared to all other noble gases. The gas phase 131Xe NMR spectrum displays a surface and magnetic field dependent quadrupolar splitting that was found to have additional gas pressure and gas composition dependence. The splitting was reduced by the presence of water vapor that presumably influences xenon-surface interactions. The hp 131Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp 131Xe NMR spectroscopy studies, a general equation for the high temperature, thermal spin polarization, P, for spin I?1/2 nuclei is presented. PMID:21051249

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

2011-01-01

85

NMR-Based Milk Metabolomics  

PubMed Central

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

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

2013-01-01

86

Development of LC-13C NMR  

NASA Technical Reports Server (NTRS)

This study involves the development of C-13 nuclear resonance as an on-line detector for liquid chromatography (LC-C-13 NMR) for the chemical characterization of aviation fuels. The initial focus of this study was the development of a high sensitivity flow C-13 NMR probe. Since C-13 NMR sensitivity is of paramount concern, considerable effort during the first year was directed at new NMR probe designs. In particular, various toroid coil designs were examined. In addition, corresponding shim coils for correcting the main magnetic field (B sub 0) homogeneity were examined. Based on these initial probe design studies, an LC-C-13 NMR probe was built and flow C-13 NMR data was obtained for a limited number of samples.

Dorn, H. C.; Wang, J. S.; Glass, T. E.

1986-01-01

87

Mesoionic compounds — structure and NMR parameters  

Microsoft Academic Search

It has been shown that1H,13C,14N,15N,17O, and77Se NMR are very successful techniques for the identification and investigation of potential valence tautomerism in all types of mesoionic compounds. Especially the combined use of14N and15N NMR studies has been shown to be very effective in solving structural problems. From15N NMR it is possible to obtain accurate chemical shifts and spin-spin couplings, whereas the14N

Lech Stefaniak; Jaroslaw Ja?wi?ski

1995-01-01

88

Protein Structure from Solid-State NMR  

Microsoft Academic Search

\\u000a This article deals with mathematical questions arising from the determination of protein structure from data obtained by solid-state\\u000a nuclear magnetic resonance (NMR). Solid-state NMR holds the promise of revealing the structure of membrane proteins in a lipid\\u000a bilayer. The derivation of protein structure from NMR data has most often been done using proteins in liquid state, and the\\u000a mathematical analysis

John R. Quine; Timothy A. Cross

2003-01-01

89

Applications of NMR in Dairy Research  

PubMed Central

NMR is a robust analytical technique that has been employed to investigate the properties of many substances of agricultural relevance. NMR was first used to investigate the properties of milk in the 1950s and has since been employed in a wide range of studies; including properties analysis of specific milk proteins to metabolomics techniques used to monitor the health of dairy cows. In this brief review, we highlight the different uses of NMR in the dairy industry. PMID:24958391

Maher, Anthony D.; Rochfort, Simone J.

2014-01-01

90

Solid-state NMR and membrane proteins.  

PubMed

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

Opella, Stanley J

2015-04-01

91

Multiple quantum NMR dynamics in pseudopure states.  

PubMed

We investigate numerically the multiple quantum (MQ) NMR dynamics in systems of nuclear spins 1/2 coupled by dipole-dipole interactions in the case of the pseudopure initial state. Simulations of the MQ NMR with real molecular structures such as six dipolar-coupled proton spins of benzene, hydroxyl proton chains in calcium hydroxyapatite, and fluorine chains in calcium fluorapatite open the way to experimental NMR testing of the obtained results. It was found that multiple-spin correlations are created faster in such experiments than in the usual MQ NMR experiments and can be used for the investigation of many-spin dynamics of nuclear spins in solids. PMID:21814001

Furman, G B

2009-01-14

92

Multiple quantum NMR dynamics in pseudopure states  

NASA Astrophysics Data System (ADS)

We investigate numerically the multiple quantum (MQ) NMR dynamics in systems of nuclear spins 1/2 coupled by dipole-dipole interactions in the case of the pseudopure initial state. Simulations of the MQ NMR with real molecular structures such as six dipolar-coupled proton spins of benzene, hydroxyl proton chains in calcium hydroxyapatite, and fluorine chains in calcium fluorapatite open the way to experimental NMR testing of the obtained results. It was found that multiple-spin correlations are created faster in such experiments than in the usual MQ NMR experiments and can be used for the investigation of many-spin dynamics of nuclear spins in solids.

Furman, G. B.

2009-01-01

93

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

ERIC Educational Resources Information Center

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

Mills, Nancy S.; Shanklin, Michael

2011-01-01

94

jsNMR: an embedded platform-independent NMR spectrum viewer.  

PubMed

jsNMR is a lightweight NMR spectrum viewer written in JavaScript/HyperText Markup Language (HTML), which provides a cross-platform spectrum visualizer that runs on all computer architectures including mobile devices. Experimental (and simulated) datasets are easily opened in jsNMR by (i) drag and drop on a jsNMR browser window, (ii) by preparing a jsNMR file from the jsNMR web site, or (iii) by mailing the raw data to the jsNMR web portal. jsNMR embeds the original data in the HTML file, so a jsNMR file is a self-transforming dataset that may be exported to various formats, e.g. comma-separated values. The main applications of jsNMR are to provide easy access to NMR data without the need for dedicated software installed and to provide the possibility to visualize NMR spectra on web sites. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25641013

Vosegaard, Thomas

2015-04-01

95

NMR View: A computer program for the visualization and analysis of NMR data  

Microsoft Academic Search

NMR View is a computer program designed for the visualization and analysis of NMR data. It allows the user to interact with a practically unlimited number of 2D, 3D and 4D NMR data files. Any number of spectral windows can be displayed on the screen in any size and location. Automatic peak picking and facilitated peak analysis features are included

Bruce A. Johnson; Richard A. Blevins

1994-01-01

96

Probing surface interactions by combining NMR cryoporometry and NMR relaxometry  

NASA Astrophysics Data System (ADS)

To further expand on the understanding of surface interactions at the liquid/solid interface on pore walls, the nuclear magnetic resonance (NMR) techniques of cryoporometry and relaxometry have been combined. The combination of these techniques allows variations in NMR relaxation parameters from pore surface to volume ratio changes and from surface interaction changes to be distinguished. By studying a range of sol-gel silicas from two different sources, it was noted that the relaxation time measurements were not consistent with the pore diameters determined by cryoporometry and N2 gas adsorption. Instead distinctly different relaxivity constants were determined for each absorbate in each of the two brands of silica. It was clear that the relaxation times were modified by more than just the pore geometry. Independent experiments on the two brands of silica suggested that the relaxometry results were heavily influenced by the concentration of paramagnetic relaxation centres in the silica gels. The strength of surface interaction, and hence surface affinity, was seen to depend on the liquid in the pores. Using this difference in surface affinities, binary mixtures of alkanes placed in sol-gel silicas were separated via preferential absorption and their components identified using cryoporometry, whereas the components could not be distinguished in the bulk liquid.

Mitchell, J.; Stark, S. C.; Strange, J. H.

2005-06-01

97

8. R. Gao et al., Org. Lett. 3, 3719 (2001). 9. Details of 31  

E-print Network

. Gorenstein, in Phosphorus-31 NMR Principles and Applications, D. G. Gorenstein, Ed. (Academic Press, Orlando shift of the phosphorus signal indicates an unusually large R-P-R angle for a pentacoordinate phosphorus

Xie, Xiaoliang Sunney

98

Hypothesis driven assessment of an NMR curriculum  

NASA Astrophysics Data System (ADS)

The goal of this project was to develop a battery of assessments to evaluate an undergraduate NMR curriculum at Penn State University. As a chemical education project, we sought to approach the problem of curriculum assessment from a scientific perspective, while remaining grounded in the education research literature and practices. We chose the phrase hypothesis driven assessment to convey this process of relating the scientific method to the study of educational methods, modules, and curricula. We began from a hypothesis, that deeper understanding of one particular analytical technique (NMR) will increase undergraduate students' abilities to solve chemical problems. We designed an experiment to investigate this hypothesis, and data collected were analyzed and interpreted in light of the hypothesis and several related research questions. The expansion of the NMR curriculum at Penn State was funded through the NSF's Course, Curriculum, and Laboratory Improvement (CCLI) program, and assessment was required. The goal of this project, as stated in the grant proposal, was to provide NMR content in greater depth by integrating NMR modules throughout the curriculum in physical chemistry, instrumental, and organic chemistry laboratory courses. Hands-on contact with the NMR spectrometer and NMR data and repeated exposure of the analytical technique within different contexts (courses) were unique factors of this curriculum. Therefore, we maintained a focus on these aspects throughout the evaluation process. The most challenging and time-consuming aspect of any assessment is the development of testing instruments and methods to provide useful data. After key variables were defined, testing instruments were designed to measure these variables based on educational literature (Chapter 2). The primary variables measured in this assessment were: depth of understanding of NMR, basic NMR knowledge, problem solving skills (HETCOR problem), confidence for skills used in class (within the hands-on NMR modules), confidence for NMR tasks (not practiced), and confidence for general science tasks. Detailed discussion of the instruments, testing methods and experimental design used in this assessment are provided (Chapter 3). All data were analyzed quantitatively using methods adapted from the educational literature (Chapter 4). Data were analyzed and the descriptive statistics, independent t-tests between the experimental and control groups, and correlation statistics were calculated for each variable. In addition, for those variables included on the pretest, dependent t-tests between pretest and posttest scores were also calculated. The results of study 1 and study 2 were used to draw conclusions based on the hypothesis and research questions proposed in this work (Chapter 4). Data collected in this assessment were used to answer the following research questions: (1) Primary research question: Is depth of understanding of NMR linked to problem solving skills? (2) Are the NMR modules working as intended? Do they promote depth of understanding of NMR? (a) Will students who complete NMR modules have a greater depth of understanding of NMR than students who do not complete the modules? (b) Is depth of understanding increasing over the course of the experiment? (3) Is confidence an intermediary between depth of understanding and problem solving skills? Is it linked to both variables? (4) What levels of confidence are affected by the NMR modules? (a) Will confidence for the NMR class skills used in the modules themselves be greater for those who have completed the modules? (b) Will confidence for NMR tasks not practiced in the course be affected? (c) Will confidence for general science tasks be affected? (d) Are different levels of confidence (class skills, NMR tasks, general science tasks) linked to each other? Results from this NMR curriculum assessment could also have implications outside of the courses studied, and so there is potential to impact the chemical education community (section 5.2.1). In addition to providing reliable testing instrume

Cossey, Kimberly

99

NMR studies of oriented molecules  

SciTech Connect

Deuterium and proton magnetic resonance are used in experiments on a number of compounds which either form liquid crystal mesophases themselves or are dissolved in a liquid crystal solvent. Proton multiple quantum NMR is used to simplify complicated spectra. The theory of nonselective multiple quantum NMR is briefly reviewed. Benzene dissolved in a liquid crystal are used to demonstrate several outcomes of the theory. Experimental studies include proton and deuterium single quantum (..delta..M = +-1) and proton multiple quantum spectra of several molecules which contain the biphenyl moiety. 4-Cyano-4'-n-pentyl-d/sub 11/-biphenyl (5CB-d/sub 11/) is studied as a pure compound in the nematic phase. The obtained chain order parameters and dipolar couplings agree closely with previous results. Models for the effective symmetry of the biphenyl group in 5CB-d/sub 11/ are tested against the experimental spectra. The dihedral angle, defined by the planes containing the rings of the biphenyl group, is found to be 30 +- 2/sup 0/ for 5DB-d/sub 11/. Experiments are also described for 4,4'-d/sub 2/-biphenyl, 4,4' - dibromo-biphenyl, and unsubstituted biphenyl.

Sinton, S.W.

1981-11-01

100

University of Oregon CAMCOR NMR Facility Varian NMR Instrument Guidelines (VnmrJ 3.2 software)  

E-print Network

University of Oregon CAMCOR NMR Facility Varian NMR Instrument Guidelines (VnmrJ 3.2 software) NMR: Experiments > Proton (top menu bar) Every Session (Varian spectrometers): Select solvent: Start > Standard

101

Solid-State NMR Studies of Bone  

Microsoft Academic Search

Solid-state NMR studies on bone, bone mineral standards and collagen are reviewed. NMR spectroscopy was mostly applied to the bone mineral and confirmed that the structure resembles that of calcium carbonatoapatite of type B. Apatite in bone was found to be deficient in structural hydroxyl groups. Concentration and distribution of hydrogenphosphate and carbonate ions, and of water in apatite crystals

Waclaw Kolodziejski

102

Liquid-State NMR Quantum Computing  

E-print Network

Liquid-State NMR Quantum Computing Lieven M. K. Vandersypen TU Delft, Delft, the Netherlands Isaac, Dortmund, Germany 1 Introduction 1 2 Quantum Computation 1 3 NMR Quantum Computers 5 4 Summary of doing computation becomes possible, which is known as quantum computation (QC). Quantum computing

Suter, Dieter

103

An Integrated Laboratory Project in NMR Spectroscopy.  

ERIC Educational Resources Information Center

Describes an advanced NMR project that can be done with a 60-MHz continuous-wave proton spectrometer. Points out the main purposes are to give students experience in second-order NMR analysis, the simplification of spectra by raising the frequency, and the effect of non-hydrogen nuclei on proton resonances. (MVL)

Hudson, Reggie L.; Pendley, Bradford D.

1988-01-01

104

Using Cloud Storage for NMR Data Distribution  

ERIC Educational Resources Information Center

An approach using Google Groups as method for distributing student-acquired NMR data has been implemented. We describe how to configure NMR spectrometer software so that data is uploaded to a laboratory section specific Google Group, thereby removing bottlenecks associated with printing and processing at the spectrometer workstation. Outside of…

Soulsby, David

2012-01-01

105

An Inversion Recovery NMR Kinetics Experiment  

ERIC Educational Resources Information Center

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

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

2011-01-01

106

NMR Spectroscopy and Its Value: A Primer  

ERIC Educational Resources Information Center

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

Veeraraghavan, Sudha

2008-01-01

107

Enzyme dynamics from NMR spectroscopy.  

PubMed

Conspectus Biological activities of enzymes, including regulation or coordination of mechanistic stages preceding or following the chemical step, may depend upon kinetic or equilibrium changes in protein conformations. Exchange of more open or flexible conformational states with more closed or constrained states can influence inhibition, allosteric regulation, substrate recognition, formation of the Michaelis complex, side reactions, and product release. NMR spectroscopy has long been applied to the study of conformational dynamic processes in enzymes because these phenomena can be characterized over multiple time scales with atomic site resolution. Laboratory-frame spin-relaxation measurements, sensitive to reorientational motions on picosecond-nanosecond time scales, and rotating-frame relaxation-dispersion measurements, sensitive to chemical exchange processes on microsecond-millisecond time scales, provide information on both conformational distributions and kinetics. This Account reviews NMR spin relaxation studies of the enzymes ribonuclease HI from mesophilic (Escherichia coli) and thermophilic (Thermus thermophilus) bacteria, E. coli AlkB, and Saccharomyces cerevisiae triosephosphate isomerase to illustrate the contributions of conformational flexibility and dynamics to diverse steps in enzyme mechanism. Spin relaxation measurements and molecular dynamics (MD) simulations of the bacterial ribonuclease H enzymes show that the handle region, one of three loop regions that interact with substrates, interconverts between two conformations. Comparison of these conformations with the structure of the complex between Homo sapiens ribonuclease H and a DNA:RNA substrate suggests that the more closed state is inhibitory to binding. The large population of the closed conformation in T. thermophilus ribonuclease H contributes to the increased Michaelis constant compared with the E. coli enzyme. NMR spin relaxation and fluorescence spectroscopy have characterized a conformational transition in AlkB between an open state, in which the side chains of methionine residues in the active site are disordered, and a closed state, in which these residues are ordered. The open state is highly populated in the AlkB/Zn(II) complex, and the closed state is highly populated in the AlkB/Zn(II)/2OG/substrate complex, in which 2OG is the 2-oxoglutarate cosubstrate and the substrate is a methylated DNA oligonucleotide. The equilibrium is shifted to approximately equal populations of the two conformations in the AlkB/Zn(II)/2OG complex. The conformational shift induced by 2OG ensures that 2OG binds to AlkB/Zn(II) prior to the substrate. In addition, the opening rate of the closed conformation limits premature release of substrate, preventing generation of toxic side products by reaction with water. Closure of active site loop 6 in triosephosphate isomerase is critical for forming the Michaelis complex, but reopening of the loop after the reaction is (partially) rate limiting. NMR spin relaxation and MD simulations of triosephosphate isomerase in complex with glycerol 3-phosphate demonstrate that closure of loop 6 is a highly correlated rigid-body motion. The MD simulations also indicate that motions of Gly173 in the most flexible region of loop 6 contribute to opening of the active site loop for product release. Considered together, these three enzyme systems illustrate the power of NMR spin relaxation investigations in providing global insights into the role of conformational dynamic processes in the mechanisms of enzymes from initial activation to final product release. PMID:25574774

Palmer, Arthur G

2015-02-17

108

NMR and MRI apparatus and method  

DOEpatents

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

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

2007-03-06

109

Preprocessing of NMR metabolomics data.  

PubMed

Abstract Metabolomics involves the large scale analysis of metabolites and thus, provides information regarding cellular processes in a biological sample. Independently of the analytical technique used, a vast amount of data is always acquired when carrying out metabolomics studies; this results in complex datasets with large amounts of variables. This type of data requires multivariate statistical analysis for its proper biological interpretation. Prior to multivariate analysis, preprocessing of the data must be carried out to remove unwanted variation such as instrumental or experimental artifacts. This review aims to outline the steps in the preprocessing of NMR metabolomics data and describe some of the methods to perform these. Since using different preprocessing methods may produce different results, it is important that an appropriate pipeline exists for the selection of the optimal combination of methods in the preprocessing workflow. PMID:25738209

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

2015-05-01

110

An introduction to biological NMR spectroscopy.  

PubMed

NMR spectroscopy is a powerful tool for biologists interested in the structure, dynamics, and interactions of biological macromolecules. This review aims at presenting in an accessible manner the requirements and limitations of this technique. As an introduction, the history of NMR will highlight how the method evolved from physics to chemistry and finally to biology over several decades. We then introduce the NMR spectral parameters used in structural biology, namely the chemical shift, the J-coupling, nuclear Overhauser effects, and residual dipolar couplings. Resonance assignment, the required step for any further NMR study, bears a resemblance to jigsaw puzzle strategy. The NMR spectral parameters are then converted into angle and distances and used as input using restrained molecular dynamics to compute a bundle of structures. When interpreting a NMR-derived structure, the biologist has to judge its quality on the basis of the statistics provided. When the 3D structure is a priori known by other means, the molecular interaction with a partner can be mapped by NMR: information on the binding interface as well as on kinetic and thermodynamic constants can be gathered. NMR is suitable to monitor, over a wide range of frequencies, protein fluctuations that play a crucial role in their biological function. In the last section of this review, intrinsically disordered proteins, which have escaped the attention of classical structural biology, are discussed in the perspective of NMR, one of the rare available techniques able to describe structural ensembles. This Tutorial is part of the International Proteomics Tutorial Programme (IPTP 16 MCP). PMID:23831612

Marion, Dominique

2013-11-01

111

An Introduction to Biological NMR Spectroscopy*  

PubMed Central

NMR spectroscopy is a powerful tool for biologists interested in the structure, dynamics, and interactions of biological macromolecules. This review aims at presenting in an accessible manner the requirements and limitations of this technique. As an introduction, the history of NMR will highlight how the method evolved from physics to chemistry and finally to biology over several decades. We then introduce the NMR spectral parameters used in structural biology, namely the chemical shift, the J-coupling, nuclear Overhauser effects, and residual dipolar couplings. Resonance assignment, the required step for any further NMR study, bears a resemblance to jigsaw puzzle strategy. The NMR spectral parameters are then converted into angle and distances and used as input using restrained molecular dynamics to compute a bundle of structures. When interpreting a NMR-derived structure, the biologist has to judge its quality on the basis of the statistics provided. When the 3D structure is a priori known by other means, the molecular interaction with a partner can be mapped by NMR: information on the binding interface as well as on kinetic and thermodynamic constants can be gathered. NMR is suitable to monitor, over a wide range of frequencies, protein fluctuations that play a crucial role in their biological function. In the last section of this review, intrinsically disordered proteins, which have escaped the attention of classical structural biology, are discussed in the perspective of NMR, one of the rare available techniques able to describe structural ensembles. This Tutorial is part of the International Proteomics Tutorial Programme (IPTP 16 MCP). PMID:23831612

Marion, Dominique

2013-01-01

112

Scalar operators in solid-state NMR  

SciTech Connect

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

Sun, Boqin

1991-11-01

113

NMR in drug discovery on membrane proteins.  

PubMed

Drug discovery on membrane proteins is still a difficult task, despite the recognized importance of membrane proteins as drug targets. Here, we present an overview of NMR methods available for structure-based drug design on membrane proteins. NMR spectroscopy is capable of identifying potential binders in screening and defining their relative binding constants, binding stoichiometry, conformation in the binding pocket and the relative binding orientation for binders of different series. Examples are given in the review highlighting the potential of NMR spectroscopy for future progress in drug discovery on membrane proteins. PMID:22571612

Wirmer-Bartoschek, Julia; Bartoschek, Stefan

2012-05-01

114

Probing porous media with gas diffusion NMR  

NASA Technical Reports Server (NTRS)

We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of porous media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate rocks.

Mair, R. W.; Wong, G. P.; Hoffmann, D.; Hurlimann, M. D.; Patz, S.; Schwartz, L. M.; Walsworth, R. L.

1999-01-01

115

STRUCTUREu DITERPENE ELUCIDATION FROM 1 3 C NMR  

E-print Network

elucidation of compounds isolated from plants, fungi, bacteria, or other organisms is a common problem products (not proteins), only 1 H NMR and 1 3 C NMR spectroscopy, including combined methods such as 2D NMR. In structure elucidation of pep- tides and proteins, 1 5 N NMR is sometimes helpful (Abraham & Loftus, 1978). 1

Dzeroski, Saso

116

Quantitative determination of mebeverine HCl by NMR chemical shift migration  

Microsoft Academic Search

Quantitative 1H NMR spectroscopic methods are not frequently reported, but current NMR instrumentation allows ready access to such data. Mebeverine HCl is an attractive molecule for NMR spectroscopy teaching purposes as it possesses a variety of simple but significant functional groups; we fully assign its 1H and 13C NMR spectra. Using mebeverine HCl, we show that concentration changes, in water

Ian S. Blagbrough; Manal S. Elmasry; Timothy J. Woodman; Hanaa M. Saleh; Afaf Aboul Kheir

2009-01-01

117

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

ERIC Educational Resources Information Center

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

Alonso, David E.; Warren, Steven E.

2005-01-01

118

NMR spectroscopy for atomistic views of biomembranes and cell surfaces NMR spectroscopy is an important analytical tool for probing  

E-print Network

and Cell Surfaces" highlight the power of NMR spectroscopy in problem-solving efforts of biological review the NMR methodology involved in the determination of mem- brane protein structures fromPreface NMR spectroscopy for atomistic views of biomembranes and cell surfaces NMR spectroscopy

Weliky, David

119

342 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 46, NO. 1, JANUARY 2011 Palm NMR and 1-Chip NMR  

E-print Network

342 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 46, NO. 1, JANUARY 2011 Palm NMR and 1-Chip NMR Nan in the palm of a hand, is the smallest NMR system ever built, and is 1200 lighter, 1200 smaller, yet 150 more, such as biomolecular sensing, medical imaging, and oil detection, to name a few. The benefits of NMR would be broadly

Ham, Donhee

120

NMR and optical studies of piezoelectric polymers  

SciTech Connect

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

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

1993-01-01

121

33S NMR cryogenic probe for taurine detection  

NASA Astrophysics Data System (ADS)

With the goal of a S33 nuclear magnetic resonance (NMR) probe applicable to in vivo NMR on taurine-biological samples, we have developed the S33 NMR cryogenic probe, which is applicable to taurine solutions. The NMR sensitivity gain relative to a conventional broadband probe is as large as 3.5. This work suggests that improvements in the preamplifier could allow NMR measurements on 100 ?M taurine solutions, which is the level of sensitivity necessary for biological samples.

Hobo, Fumio; Takahashi, Masato; Maeda, Hideaki

2009-03-01

122

NMR mechanisms in gel dosimetry  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance was critical to the development of gel dosimetry, as it established the potential for three dimensional dosimetry with chemical dosimeter systems through magnetic resonance imaging [1]. In the last two decades MRI has served as the gold standard for imaging, while NMR relaxometry has played an important role in the development and understanding of the behaviour of new gel dosimetry systems. Therefore, an appreciation of the relaxation mechanisms determining the NMR behaviour of irradiated gel dosimeters is important for a full comprehension of a considerable component of the literature on gel dosimetry. A number of excellent papers have presented this important theory, this brief review will highlight some of the salient points made previously [1-5]. The spin relaxation of gel dosimeters (which determines the dose dependence in most conventional MR imaging) is determined principally by the protons on water molecules in the system. These water protons exist in different environments, or groups (see Figure 1): on bulk water, on water hydrating the chemical species that are being modified under irradiation, and on water hydrating the gel matrix used to spatially stabilize the dosimeter (e.g., gelatin, agarose, etc). The spin relaxation depends on the inherent relaxation rate of each spin group, that is, on the relaxation rate which would be observed for the specific group if it were isolated. Also, the different water environments are not isolated from each other, and the observed relaxation rate also depends on the rate of exchange of magnetization between the groups, and on the fraction of protons in each group. In fact, the water exchanges quickly between the environments, so that relaxation is in what is usually termed the fast exchange regime. In the limit of fast exchange, the relaxation of the water protons is well characterized by a single exponential and hence by a single apparent relaxation rate. In irradiated gel dosimeters this observed rate is a function of the absorbed dose. In this review I will first develop the fast exchange model for the spin lattice relaxation Fricke gel dosimeter system, as this is conceptually the simpler system. Fundamental concepts such as relaxivity (which specifies the ability of some species to enhance the relaxation of water protons) and chemical yield will be presented. The linear dose relationship for Fricke gel dosimeters, and the reduced dose sensitivity of Fricke dosimeters containing chelators, will be explained. The model will then be extended to the spin-spin relaxation of polymer gel systems and the main differences discussed. The reasons for the enhanced dose sensitivy and dynamic range for spin-spin (R2) rather than spin-lattice (R1) relaxation will be presented.

Schreiner, L. J.

2009-05-01

123

Diffusion NMR of molecular cages and capsules.  

PubMed

In the last decade diffusion NMR and diffusion ordered spectroscopy (DOSY) have become important analytical tools for the characterization of supramolecular systems in solution. Diffusion NMR can be used to glean information on the (effective) size and shape of molecular species, as well as to probe inter-molecular interactions and can be used to estimate the association constant (Ka) of a complex. In addition, the diffusion coefficient, as obtained from diffusion NMR, is a much more intuitive parameter than the chemical shift for probing self-association, aggregation and inter-molecular interactions. The diffusion coefficient may be an even more important analytical parameter in systems in which the formed supramolecular entity has the same symmetry as its building units, when there is a large change in the molecular weight, where many molecular species are involved in the formation of the supramolecular systems, and when proton transfer may occur which, in turn, may affect the chemical shift. Some of the self-assembled molecular capsules and cages prepared in the last decade represent such supramolecular systems and in the present review, following a short introduction on diffusion NMR, we survey the contribution of diffusion NMR and DOSY in the field of molecular containers and capsules. We will first focus on the role played by diffusion NMR in the field of hydrogen bond driven self-assembled capsules. We then survey the contributions of diffusion NMR and DOSY to the study and characterization of metal-ligand cages and capsules. Finally, we describe a few recent applications of diffusion NMR in the field of hydrophobic, electrostatic and covalent containers. PMID:25110858

Avram, Liat; Cohen, Yoram

2015-01-21

124

Frontiers of NMR in Molecular Biology  

SciTech Connect

NMR spectroscopy is expanding the horizons of structural biology by determining the structures and describing the dynamics of blobular proteins in aqueous solution, as well as other classes of proteins including membrane proteins and the polypeptides that form the aggregates diagnostic of prion and amyloid diseases. Significant results are also emerging on DNA and RNA oligomers and their complexes with proteins. This meeting focused attention on key structural questions emanating from molecular biology and how NMR spectroscopy can be used to answer them.

NONE

1999-08-25

125

NMR study of trialuminide intermetallics  

NASA Astrophysics Data System (ADS)

We present a systematic study of the DO22-structure trialuminide intermetallic alloys using 27Al NMR spectroscopy. The quadrupole splittings, Knight shifts, and spin-lattice relaxation times on Al3Ti, Al3V, Al3Nb, and Al3Ta have been identified. Knight-shift tensors were isolated by observation of quadrupole satellite lines and fitting to the central-transition powder patterns. The results are associated with the local electronic density of states for each crystallographic site. Universally small isotropic Knight shifts and long T1's are consistent with low Fermi-surface densities of states indicating the importance of Fermi-surface features for the phase stability of these alloys. Larger anisotropic Knight shifts occurring at aluminum site I indicate strong hybridization at this site, and the electric-field-gradient tensors confirm the strong ab plane bonding configuration. Local-moment magnetism is found in Al3V, yet electrically this material appears very similar to the other DO22 aluminides.

Lue, Chin-Shan; Chepin, Suchitra; Chepin, James; Ross, Joseph H., Jr.

1998-03-01

126

NMR Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) is an effect whereby magnetic nuclei in  

E-print Network

NMR Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) is an effect whereby magnetic resonance frequency which depends on the strength of the magnetic field and other factors. This allows nuclei in a magnetic field absorb and re-emit electromagnetic (EM) energy. This energy is at a specific

Cavanagh, John

127

Use of NMR and NMR Prediction Software to Identify Components in Red Bull Energy Drinks  

ERIC Educational Resources Information Center

A laboratory experiment designed as part of an upper-level undergraduate analytical chemistry course is described. Students investigate two popular soft drinks (Red Bull Energy Drink and sugar-free Red Bull Energy Drink) by NMR spectroscopy. With assistance of modern NMR prediction software they identify and quantify major components in each…

Simpson, Andre J.; Shirzadi, Azadeh; Burrow, Timothy E.; Dicks, Andrew P.; Lefebvre, Brent; Corrin, Tricia

2009-01-01

128

NMR techniques in the study of cardiovascular structure and functions  

SciTech Connect

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

Osbakken, M.; Haselgrove, J.

1987-01-01

129

Nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging  

DOEpatents

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Fukushima, Eiichi (Los Alamos, NM); Roeder, Stephen B. W. (La Mesa, CA); Assink, Roger A. (Albuquerque, NM); Gibson, Atholl A. V. (Bryan, TX)

1986-01-01

130

BOOK REVIEW: NMR Imaging of Materials  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) of materials is a field of increasing importance. Applications extend from fundamental science like the characterization of fluid transport in porous rock, catalyst pellets and hemodialysers into various fields of engineering for process optimization and product quality control. While the results of MRI imaging are being appreciated by a growing community, the methods of imaging are far more diverse for materials applications than for medical imaging of human beings. Blümich has delivered the first book in this field. It was published in hardback three years ago and is now offered as a paperback for nearly half the price. The text provides an introduction to MRI imaging of materials covering solid-state NMR spectroscopy, imaging methods for liquid and solid samples, and unusual MRI in terms of specialized approaches to spatial resolution such as an MRI surface scanner. The book represents an excellent and thorough treatment which will help to grow research in materials MRI. Blümich developed the treatise over many years for his research students, graduates in chemistry, physics and engineering. But it may also be useful for medical students looking for a less formal discussion of solid-state NMR spectroscopy. The structure of this book is easy to perceive. The first three chapters cover an introduction, the fundamentals and methods of solid-state NMR spectroscopy. The book starts at the ground level where no previous knowledge about NMR is assumed. Chapter 4 discusses a wide variety of transformations beyond the Fourier transformation. In particular, the Hadamard transformation and the 'wavelet' transformation are missing from most related books. This chapter also includes a description of noise-correlation spectroscopy, which promises the imaging of large objects without the need for extremely powerful radio-frequency transmitters. Chapters 5 and 6 cover basic imaging methods. The following chapter about the use of relaxation and spectroscopic methods to weight or filter the spin signals represents the core of the book. This is a subject where Blümich is deeply involved with substantial contributions. The chapter includes a lot of ideas to provide MR contrast between different regions based on their mobility, diffusion, spin couplings or NMR spectra. After describing NMR imaging methods for solids with broad lines, Blümich spends time on applications in the last two chapters of the book. This part is really fun to read. It underlines the effort to bring NMR into many kinds of manufacturing. Car tyres and high-voltage cables are just two such areas. Elastomeric materials, green-state ceramics and food science represent other interesting fields of applications. This part of the book represents a personal but nevertheless extensive compilation of modern applications. As a matter of course the MOUSE is presented, a portable permanent-magnet based NMR developed by Blümich and his co-workers. Thus the book is not only of interest to NMR spectroscopists but also to people in material science and chemical engineering. The bibliography and indexing are excellent and may serve as an attractive reference source for NMR spectroscopists. The book is the first on the subject and likely to become the standard text for NMR imaging of materials as the books by Abragam, Slicher and Ernst et al are for NMR spectroscopy. The purchase of this beautiful book for people dealing with NMR spectroscopy or medical MRI is highly recommended. Ralf Ludwig

Blümich, Bernhard

2003-09-01

131

NMR methodologies in the analysis of blueberries.  

PubMed

An NMR analytical protocol based on complementary high and low field measurements is proposed for blueberry characterization. Untargeted NMR metabolite profiling of blueberries aqueous and organic extracts as well as targeted NMR analysis focused on anthocyanins and other phenols are reported. Bligh-Dyer and microwave-assisted extractions were carried out and compared showing a better recovery of lipidic fraction in the case of microwave procedure. Water-soluble metabolites belonging to different classes such as sugars, amino acids, organic acids, and phenolic compounds, as well as metabolites soluble in organic solvent such as triglycerides, sterols, and fatty acids, were identified. Five anthocyanins (malvidin-3-glucoside, malvidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-galactoside, and petunidin-3-glucoside) and 3-O-?-l-rhamnopyranosyl quercetin were identified in solid phase extract. The water status of fresh and withered blueberries was monitored by portable NMR and fast-field cycling NMR. (1) H depth profiles, T2 transverse relaxation times and dispersion profiles were found to be sensitive to the withering. PMID:24668393

Capitani, Donatella; Sobolev, Anatoly P; Delfini, Maurizio; Vista, Silvia; Antiochia, Riccarda; Proietti, Noemi; Bubici, Salvatore; Ferrante, Gianni; Carradori, Simone; De Salvador, Flavio Roberto; Mannina, Luisa

2014-06-01

132

Biological NMR FIDs and spectra normalization  

NASA Astrophysics Data System (ADS)

There is increasing use of spectroscopic techniques, such as high-resolution NMR spectroscopy, to examine variations in cell metabolism and / or structure in response to numerous physical, chemical, and biological agents. In these types of studies, in order to obtain relative quantitative information, a comparison between signal intensities of control samples and treated or exposed ones is often conducted. The methods thus far developed for this purpose are not directly related to the overall intrinsic properties of the samples, but rather to the addition of external substances of known concentrations or to indirect measurement of internal substances. Another possibility is to estimate, by an opportune algorithm, a normalization constant which takes into consideration all cell metabolites present in the sample. Recently, a new normalization algorithm, based on Principal Component Analysis (PCA), was presented. PCA is a well-known statistical technique for analysis of large, multivariate datasets, which extracts the basic features of the data. The PRICONA (PRincipal COmponent Normalization Algorithm) algorithm use PCA in a new totally different manner: PCA is, in fact, used to normalize spectra in order to obtain quantitative information about the treatment effects. In this paper, a comparison of results obtained in the time domain, that is on NMR FIDs (Free Induction Decay) and in the frequency domain, on NMR spectra, is conducted. The comparison is useful because in NMR spectroscopy analysis in the different domain can have different advantages. The algorithm was tested by Monte Carlo simulations of NMR FIDs.

Romano, R.; Canonico, R.; Acernese, F.; Giordano, G.; Barone, F.

2014-03-01

133

Antigen-antibody interactions: an NMR approach.  

PubMed

With recent advances in methodology, it now appears that NMR can be used at an unprecedented level of sophistication to obtain new insights into the solution structure and dynamics of the antibody combining site, both free and in its complex with antigen. Most promising in this regard is the Fv fragment (molecular weight approximately 25 kD) which can be produced by genetic engineering in a form suitable for NMR studies. Isotopic labeling is required to make specific resonance assignments. NMR can also provide information on the conformational preferences of immunogenic peptides and can be used to probe the conformation and dynamics of peptides (appropriately labeled with 13C or 15N) bound to the Fab fragment (molecular weight approximately 50 kD) of antipeptide antibodies. PMID:1695509

Wright, P E; Dyson, H J; Lerner, R A; Riechmann, L; Tsang, P

1990-07-01

134

An optical NMR spectrometer for Larmor-beat detection and high-resolution POWER NMR  

NASA Astrophysics Data System (ADS)

Optical nuclear magnetic resonance (ONMR) is a powerful probe of electronic properties in III-V semiconductors. Larmor-beat detection (LBD) is a sensitivity optimized, time-domain NMR version of optical detection based on the Hanle effect. Combining LBD ONMR with the line-narrowing method of POWER (perturbations observed with enhanced resolution) NMR further enables atomically detailed views of local electronic features in III-Vs. POWER NMR spectra display the distribution of resonance shifts or line splittings introduced by a perturbation, such as optical excitation or application of an electric field, that is synchronized with a NMR multiple-pulse time-suspension sequence. Meanwhile, ONMR provides the requisite sensitivity and spatial selectivity to isolate local signals within macroscopic samples. Optical NMR, LBD, and the POWER method each introduce unique demands on instrumentation. Here, we detail the design and implementation of our system, including cryogenic, optical, and radio-frequency components. The result is a flexible, low-cost system with important applications in semiconductor electronics and spin physics. We also demonstrate the performance of our systems with high-resolution ONMR spectra of an epitaxial AlGaAs /GaAs heterojunction. NMR linewidths down to 4.1Hz full width at half maximum were obtained, a 103-fold resolution enhancement relative any previous optically detected NMR experiment.

Kempf, J. G.; Marohn, J. A.; Carson, P. J.; Shykind, D. A.; Hwang, J. Y.; Miller, M. A.; Weitekamp, D. P.

2008-06-01

135

An NMR Study of Microvoids in Polymers  

NASA Technical Reports Server (NTRS)

An understanding of polymer defect structures, like microvoids in polymeric matrices, is most crucial to their fabrication and application potential. In this project guest atoms are introduced into the microvoids in PMR-15 and NMR is used to determine microvoid sizes and locations. Xenon is a relatively inert probe that would normally not be found naturally in polymer or in NMR probe materials. There are two NMR active Xenon isotopes, Xe-129 and Xe-131. The Xe atom has a very high polarizability, which makes it sensitive to the intracrystalline environment of polymers. Interactions between the Xe atoms and the host matrix perturb and Xe electron cloud, deshielding the nuclei, and thereby expanding the range of the observed NMR chemical shifts. This chemical shift range which may be as large as 5000 ppm, permits subtle structural and chemical effects to be studied with high sensitivity. The Xe-129-NMR line shape has been found to vary in response to changes in the pore symmetry of the framework hosts in Zeolites and Clathrasil compounds. Before exposure to Xe gas, the PMR-15 samples were dried in a vacuum oven at 150 C for 48 hours. The samples were then exposed to Xe gas at 30 psi for 72 hours and sealed in glass tubes with 1 atmosphere of Xenon gas. Xenon gas at 1 atmosphere was used to tune up the spectrometer and to set up the appropriate NMR parameters. A series of spectra were obtained interspersed with applications of vacuum and heating to drive out the adsorbed Xe and determine the role of Xe-Xe interactions in the observed chemical shift.

Toy, James; Mattrix, Larry

1996-01-01

136

Hyperpolarized Xenon for NMR and MRI Applications  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2. Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

2012-01-01

137

NMR Stark Spectroscopy: New Methods to Calibrate NMR Sensitivity to Electric Fields  

NASA Astrophysics Data System (ADS)

The influence of electrostatics on NMR parameters is well accepted. Thus, NMR is a promising route to probe electrical features within molecules and materials. However, applications of NMR Stark effects (E-field induced changes in spin energy levels) have been elusive. I have developed new approaches to resolve NMR Stark effects from an applied E field. This calibrates nuclear probes whose spectral response might later be used to evaluate internal E fields that are critical to function, such as those due to local charge distributions or sample structure. I will present two novel experimental approaches for direct calibration of NMR quadrupolar Stark effects (QSEs). In the first, steady-state (few-second) excitation by an E field at twice the NMR frequency (2? 0) is used to saturate spin magnetization. The extent of saturation vs. E-field amplitude calibrates the QSE response rate, while measurements vs sample orientation determine tensorial character. The second method instead synchronizes short (few µs) pulses of the 2?0 E field with a multiple-pulse NMR sequence. This, “POWER” (Perturbations Observed With Enhanced Resolution) approach enables more accurate measure of small QSEs (i.e. few Hz spectral changes). A 2nd key advantage is the ability to define tensorial response without reorienting the sample, but instead varying the phase of the 2?0 field. I will describe these experiments and my home-built NMR “Stark probe”, employed on a conventional wide-bore solid-state NMR system. Results with GaAs demonstrate each method, while extensions to a wider array of molecular and material systems may now be possible using these methods.

Tarasek, Matthew R.

138

The Quiet Renaissance of Protein NMR  

PubMed Central

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

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

2013-01-01

139

New Designs for NMR Core Scanning  

NASA Astrophysics Data System (ADS)

Within the last ten years, mobile magnetic resonance has moved from the oil field to many new areas of application. While the focus of mobile NMR in the past was on single-sided or inside-out NMR, the advent of tube-shaped Halbach magnets has introduced the conventional outside-in NMR concept to mobile NMR where the object is inside a magnet. Our Halbach magnet is constructed from small magnet blocks at light weight and low cost with a magnetic field sufficiently homogeneous. To automatize NMR measurements, the Halbach magnet is mounted on a sliding table to scan long core sections without human interaction. In homogeneous magnetic fields, the longitudinal relaxation time T1 and even the transverse relaxation time T2 are proportional to the pore diameters of rocks. Hence, the T1 and T2 signals map the pore-size distribution of the studied rock cores. For fully saturated samples the integral of the distribution curve is proportional to porosity. The porosity values from NMR measurements with the Halbach magnet are used to estimate permability. The Halbach magnet can be used for certain sample geometries in combination with exchangeable radio frequency (rf) coils with different diameters from 24 mm up to 80 mm. To measure standard Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) cores, which have a standard diameter of 60 mm and are split lengthwise after recovery, we use a surface figure-8 rf coil with an inner diameter of 60 mm. Besides 1D T2 measurements, we perform relaxation-relaxation correlation experiments, where T1 and T2 are measured in parallel. In this way, the influence of diffusion on the shape of the T2 distribution function is probed. A gradient coil system was designed to perform Pulsed Field Gradients (PFG) experiments. As the gradient coils restrict the axial access to the magnet, only cylindrical core plugs with 20 mm in diameter can be analysed by PFG NMR methods. The homogeneity of the magnetic field in the sensitive volume of 20 mm length and height is sufficient for conventional PFG experiments. Hence, in a next step we will measure tortuosity and investigate pore anisotropies by PFG NMR.

Bluemich, B.; Anferova, S.; Talnishnikh, E.; Arnold, J.; Clauser, C.

2006-12-01

140

AB Proton NMR Using Tensor Algebra Frank Rioux  

E-print Network

AB Proton NMR Using Tensor Algebra Frank Rioux Professor Emeritus of Chemistry CSB|SJU The purpose of this tutorial is to deviate from the usual matrix mechanics approach to the ABC proton nmr system in order

Rioux, Frank

141

Rapid 3D MAS NMR Spectroscopy at Critical Sensitivity  

E-print Network

Sensitive SIFTing: Multidimensional non-uniform sampling (NUS) NMR spectroscopy is extended to the severely sensitivity-limited regime typical of MAS NMR of biomacromolecules by the use of spectroscopy by the integration ...

Matsuki, Yoh

142

"In-plant" NMR: Analysis of the Intact Plant Vesicularia dubyana by High Resolution NMR Spectroscopy.  

PubMed

We present here the concept of "in-plant" NMR and show that high-resolution NMR spectroscopy is suitable for the analysis of intact plants and can be used to follow the changes in the intraorganismal molecular composition over long time periods. The NMR-based analysis of the effect of different concentrations of heavy water on the aquatic plant Vesicularia dubyana revealed that due to the presence of specific adaptive mechanisms this plant can sustain the presence of up to 85% of D2O. However, it dies in 100% heavy water. PMID:25759953

Kutyshenko, Viktor P; Beskaravayny, Peter; Uversky, Vladimir N

2015-01-01

143

Solution NMR spectroscopy beyond 25 kDa  

Microsoft Academic Search

Improvements in NMR instrumentation, higher magnetic field strengths, novel NMR experiments and new deuterium-labeling strategies have significantly increased the scope of structural problems that can now be addressed by solution NMR methods. To date, a number of structures of proteins of 30 kDa have been solved using multidimensional 15N, 13C,2H NMR techniques, and this molecular weight limit will probably be

Lewis E Kay; Kevin H Gardner

1997-01-01

144

High-Resolution, High-Pressure NMR Studies of Proteins  

Microsoft Academic Search

Advanced high-resolution NMR spectroscopy, including two-dimensional NMR techniques, combined with high pressure capability, represents a powerful new tool in the study of proteins. This contribution is organized in the following way. First, the specialized instrumentation needed for high-pressure NMR experiments is discussed, with specific emphasis on the design features and performance characteristics of a high-sensitivity, high-resolution, variable-temperature NMR probe operating

J. Jonas; L. Ballard; D. Nash

1998-01-01

145

Mobile NMR for porosity analysis of drill core sections  

Microsoft Academic Search

We apply a novel mobile nuclear magnetic resonance (NMR) scanning system, the NMR-MOUSE® (NMR-MOUSE (Nuclear Magnetic Resonance Mobile Universal Surface Explorer) is a registered trademark of RWTH Aachen University), for measuring porosity of geological drill core sections. The NMR-MOUSE® is used for transverse relaxation measurements on water-saturated core sections using a CPMG sequence with a short echo time. A regularized

Bernhard Blümich; Sofia Anferova; Renate Pechnig; Hansgeorg Pape; Juliane Arnold; Christoph Clauser

2004-01-01

146

Altered phospholipid metabolism in schizophrenia: a phosphorus 31 nuclear magnetic resonance spectroscopy study.  

PubMed

Phospholipid (PL) metabolism is investigated by in vivo 31P magnetic resonance spectroscopy (MRS). Inconsistent alterations of phosphocholine (PC), phosphoethanolamine (PE), glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) have been described in schizophrenia, which might be overcome by specific editing techniques. The selective refocused insensitive nuclei-enhanced polarization transfer (RINEPT) technique was applied in a cross-sectional study involving 11 schizophrenia spectrum disorder patients (SZP) on stable antipsychotic monotherapy and 15 matched control subjects. Metabolite signals were found to be modulated by cerebrospinal fluid (CSF) content and gray matter/brain matter ratio. Corrected metabolite concentrations of PC, GPC and PE differed between patients and controls in both subcortical and cortical regions, whereas antipsychotic medication exerted only small effects. Significant correlations were found between the severity of clinical symptoms and the assessed signals. In particular, psychotic symptoms correlated with PC levels in the cerebral cortex, depression with PC levels in the cerebellum and executive functioning with GPC in the insular and temporal cortices. In conclusion, after controlling for age and tissue composition, this investigation revealed alterations of metabolite levels in SZP and correlations with clinical properties. RINEPT 31P MRS should also be applied to at-risk-mental-state patients as well as drug-naïve and chronically treated schizophrenic patients in order to enhance the understanding of longitudinal alterations of PL metabolism in schizophrenia. PMID:24045051

Weber-Fahr, Wolfgang; Englisch, Susanne; Esser, Andrea; Tunc-Skarka, Nuran; Meyer-Lindenberg, Andreas; Ende, Gabriele; Zink, Mathias

2013-12-30

147

Phosphorus-31 MRI of cell membranes using quadratic echo line-narrowing  

NASA Astrophysics Data System (ADS)

Soft biological tissues have phosphorus concentrated in the membranes, metabolites, RNA and DNA of cells. This leads to a complicated, multi-peak ^31P nuclear magnetic resonance spectrum (including a broad membrane peak and narrow metabolite peaks), which precludes high-resolution ^31P MRI of soft tissues. This long-standing barrier has been overcome by a novel pulse sequence - the quadratic echo - recently discovered in fundamental quantum computation research. Applying time-dependent gradients in synch with a repeating pulse block enables a new route to high spatial resolution, three-dimensional ^31P MRI of the soft solid components of cells and tissues. This is a functionally different kind of MR image, since conventional ^1H MRI probes the intracellular and extracellular free water, whereas our ^31P MRI signal is dominated by the cell membrane contribution, which in turn depends on the density of mitochondria. The unique aspects of the signal should provide new insights into cellular and tissue function that compliment the information revealed by ^1H MRI. So far, various ex vivo soft tissue samples have been imaged with (sub-mm)^3 voxels. We will describe plans to enhance the spatial resolution in future work, to open a new window into cells.

Barrett, Sean; Frey, Merideth; Madri, Joseph; Michaud, Michael

2012-02-01

148

Solid state NMR measurements of conformation and conformational  

E-print Network

Solid state NMR measurements of conformation and conformational distributions in the membrane Lansing, MI, USA The solid state NMR lineshape of a protein backbone carbonyl nucleus is a general conformation in the distri- bution. These types of solid state NMR methodologies have been applied

Weliky, David

149

Ab initio NMR Chemical Shift Calculations for Biomolecular Systems  

E-print Network

molecular structures in the framework of NMR spectroscopy. Our work is concerned with the development4 Ab initio NMR Chemical Shift Calculations for Biomolecular Systems Using Fragment Molecular of fragment molecular orbital (FMO)-based NMR chemical shift calculation methods. They successfully lead

Furui, Sadaoki

150

Superoxygenated Water as an Experimental Sample for NMR Relaxometry  

ERIC Educational Resources Information Center

The increase in NMR relaxation rates as a result of dissolved paramagnetic species on the sample of superoxygenated drinking water is demonstrated. It is concluded that oxygen content in NMR samples is an important issue and can give rise to various problems in the interpretation of both spectroscopic and NMR imaging or relaxation experiments.

Nestle, Nikolaus; Dakkouri, Marwan; Rauscher, Hubert

2004-01-01

151

The acquisition of multidimensional NMR spectra within a single scan  

E-print Network

The acquisition of multidimensional NMR spectra within a single scan Lucio Frydman , Tali Scherf of multidimensional NMR domains within a single continuous acquisition is introduced and exemplified. Provided that an analyte's signal is sufficiently strong, the acquisition time of multidimensional NMR experiments can thus

Frydman, Lucio

152

Demixing of severely overlapping NMR spectra through multiple-quantum NMR.  

PubMed

We introduce an NMR method to help in the analysis of complex mixtures. The spectra of molecular fragments are obtained as the traces of a correlation spectrum of the regular (1)H NMR spectrum on one dimension with the one of the highest possible (1)H multiple-quantum (MaxQ) order. As this latter is a function of the number of distinguishable protons in a given molecular fragment, the analysis of a series of multiple-quantum spectra is required to achieve a complete assignment. This MaxQ NMR approach is likely to perform best in the case of signals concentrated in a very narrow frequency range, which is a challenging situation commonly encountered in many relevant analytical problems such as the characterization of extraction fractions (oil, plants, tissues), biological fluids, or environmentally relevant samples. As a demonstration, we apply the MaxQ NMR analysis to a mixture of 11 poly- and monocyclic aromatic hydrocarbons. PMID:20329747

Manjunatha Reddy, G N; Caldarelli, Stefano

2010-04-15

153

Hyperpolarized NMR Probes for Biological Assays  

PubMed Central

During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized) molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments. PMID:24441771

Meier, Sebastian; Jensen, Pernille R.; Karlsson, Magnus; Lerche, Mathilde H.

2014-01-01

154

Protein NMR spectroscopy: Hydrogen bonds under pressure  

NASA Astrophysics Data System (ADS)

Hydrogen bonds play a key role in defining the folding of proteins and the maintenance of their structure. A high-pressure NMR study of ubiquitin now provides unprecedented detail on the temperature and pressure dependence of its hydrogen-bond network.

Nielsen, Gerd; Schwalbe, Harald

2012-09-01

155

Algorithmic cooling and scalable NMR quantum computers  

E-print Network

Algorithmic cooling and scalable NMR quantum computers P. Oscar Boykin*, Tal Mor§ , Vwani cooling (via polarization heat bath)--a powerful method for obtaining a large number of highly polarized (quantum) bits, algorithmic cooling cleans dirty bits beyond the Shannon's bound on data compression

Mor, Tal

156

Solid-state NMR imaging system  

DOEpatents

An apparatus for use with a solid-state NMR spectrometer includes a special imaging probe with linear, high-field strength gradient fields and high-power broadband RF coils using a back projection method for data acquisition and image reconstruction, and a real-time pulse programmer adaptable for use by a conventional computer for complex high speed pulse sequences.

Gopalsami, Nachappa (Naperville, IL); Dieckman, Stephen L. (Elmhurst, IL); Ellingson, William A. (Naperville, IL)

1992-01-01

157

Molecular Structure and Dynamics by NMR Spectroscopy  

NSDL National Science Digital Library

This site provides PowerPoint slides for a lecture for a graduate-level course in NMR spectroscopy. The slides include useful animations which help to demonstrate the concepts described. While the casual student may find it hard to follow everything on the slides without an accompanying lecture, the files should be very useful for advanced students or educators putting together similar courses.

Edison, Arthur S.

158

Ensemble quantum computing by NMR?spectroscopy  

PubMed Central

A quantum computer (QC) can operate in parallel on all its possible inputs at once, but the amount of information that can be extracted from the result is limited by the phenomenon of wave function collapse. We present a new computational model, which differs from a QC only in that the result of a measurement is the expectation value of the observable, rather than a random eigenvalue thereof. Such an expectation value QC can solve nondeterministic polynomial-time complete problems in polynomial time. This observation is significant precisely because the computational model can be realized, to a certain extent, by NMR spectroscopy on macroscopic ensembles of quantum spins, namely molecules in a test tube. This is made possible by identifying a manifold of statistical spin states, called pseudo-pure states, the mathematical description of which is isomorphic to that of an isolated spin system. The result is a novel NMR computer that can be programmed much like a QC, but in other respects more closely resembles a DNA computer. Most notably, when applied to intractable combinatorial problems, an NMR computer can use an amount of sample, rather than time, which grows exponentially with the size of the problem. Although NMR computers will be limited by current technology to exhaustive searches over only 15 to 20 bits, searches over as much as 50 bits are in principle possible, and more advanced algorithms could greatly extend the range of applicability of such machines. PMID:9050830

Cory, David G.; Fahmy, Amr F.; Havel, Timothy F.

1997-01-01

159

Ensemble quantum computing by NMR spectroscopy.  

PubMed

A quantum computer (QC) can operate in parallel on all its possible inputs at once, but the amount of information that can be extracted from the result is limited by the phenomenon of wave function collapse. We present a new computational model, which differs from a QC only in that the result of a measurement is the expectation value of the observable, rather than a random eigenvalue thereof. Such an expectation value QC can solve nondeterministic polynomial-time complete problems in polynomial time. This observation is significant precisely because the computational model can be realized, to a certain extent, by NMR spectroscopy on macroscopic ensembles of quantum spins, namely molecules in a test tube. This is made possible by identifying a manifold of statistical spin states, called pseudo-pure states, the mathematical description of which is isomorphic to that of an isolated spin system. The result is a novel NMR computer that can be programmed much like a QC, but in other respects more closely resembles a DNA computer. Most notably, when applied to intractable combinatorial problems, an NMR computer can use an amount of sample, rather than time, which grows exponentially with the size of the problem. Although NMR computers will be limited by current technology to exhaustive searches over only 15 to 20 bits, searches over as much as 50 bits are in principle possible, and more advanced algorithms could greatly extend the range of applicability of such machines. PMID:9050830

Cory, D G; Fahmy, A F; Havel, T F

1997-03-01

160

Deuterium NMR of polymer dispersed liquid crystals  

NASA Astrophysics Data System (ADS)

Submicrometer-size droplets of monomeric liquid crystals dispersed in a solid polymer matrix are studied by deuterium NMR. Phase-separation processes are used to achieve droplets of a size comparable and less than the magnetic coherence length ?~0.5 ?m, of the NMR magnetic field, 4.7 T. Selectively deuterated (4'-pentoxy- and 4'-methoxy-) 4-cyanobiphenyl compounds (5OCB-d2) and (1OCB-d3) deuterated in the ? and methyl positions, respectively, provide for two different NMR measurement time scales to examine effects of the self-diffusion of the molecules confined to droplets. It is found that the line shape of the spectra depends on several factors which include self-diffusion, size, shape of the droplets, and type of anchoring on the droplet walls. Theoretical director configurations calculated for spherical and nonspherical droplets in the presence of an external field were used to simulate NMR spectra in the presence of self-diffusion. Effects due to external fields present during sample preparation are discussed.

Golemme, A.; Zumer, S.; Doane, J. W.; Neubert, M. E.

1988-01-01

161

NMR analysis of a fluorocarbon copolymer  

SciTech Connect

Vinylidene fluoride (VF/sub 2/) can be copolymerized with chlorotrifluoroethylene (CTFE) in an aqueous emulsion using a peroxide chain initiator. The physical properties of the resulting fluorocarbon polymer depend on the ratio of VF/sub 2/ to CTFE and the randomness of the copolymerization. When CTFE and VF are polymerized in an approximately 3:1 mole ratio, the resulting polymer is soluble in acetone (and other solvents) at room temperature. Using proton and fluorine-19 NMR, the mole ratio of CTFE to VF/sub 2/, the emulsifier (perfluorodecanoate) concentration, and the randomness of copolymerization can be determined. A trifluorotoluene internal standard is added to a d/sub 6/-acetone solution of the fluoropolymer. Proton NMR is used to determine the amount of VF/sub 2/. Fluorine-19 NMR is used to measure the amount of emulsifier and the randomness of copolymerization. Each analysis requires about 5 minutes, and is quite precise, with relative standard deviations from 3 to 10% (10 replicates analyzed). In addition, the results from NMR analyses agree well with wet chemical analyses. 4 refs., 3 figs., 3 tabs.

Smith, R.E.; Smith, C.H.

1987-10-01

162

Sample patterning on NMR surface microcoils  

NASA Astrophysics Data System (ADS)

Aligned microcontact printing for patterning the sample in areas of homogeneous RF-field on the highly sensitive surface of planar NMR microprobes is presented. We experimentally demonstrate that sample patterning allows drastic improvement of the spin excitation uniformity. The NMR microprobes are designed for cell analysis and characterized using lipid vesicles as cell substitutes. Lipid vesicles are advantageous as composition and concentration of the confined solution are precisely controlled and because of their similarity to living cells. Using aligned microcontact printing, a monolayer of lipid vesicles is immobilized on the surface of the planar NMR microprobe in a patterned way. 1H NMR spectra and CPMG spin echoes of sucrose solution confined within the lipid vesicles are successfully recorded. Nutation curves of the sample structured in different patterns demonstrate the impact of patterning on the spin excitation uniformity. The total detection volumes are between 1 and 2 nL and derived with help of a theoretic model based on 3D finite element simulation. This model predicts the signal-to-noise ratio and the progression of the nutation curves.

Ehrmann, K.; Gersbach, M.; Pascoal, P.; Vincent, F.; Massin, C.; Stamou, D.; Besse, P.-A.; Vogel, H.; Popovic, R. S.

2006-01-01

163

Structural Studies of Biological Solids Using NMR  

NASA Astrophysics Data System (ADS)

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

Ramamoorthy, Ayyalusamy

2011-03-01

164

High-Pressure Protein Crystallography and NMR  

E-print Network

High-Pressure Protein Crystallography and NMR to Explore Protein Conformations Marcus D. Collins,1, energy landscape, protein thermodynamics, pressure cryocooling Abstract High-pressure methods for solving's native conformation, but also the higher free energy conformations. The ability of high-pressure meth

Gruner, Sol M.

165

An NMR study of microvoids in polymers  

NASA Technical Reports Server (NTRS)

An understanding of polymer defect structures, like microvoids in polymeric matrices, is crucial to their fabrication and application potential. In this project guest atoms are introduced into the microvoids in PMR-15 and NMR is used to determine microvoid sizes and locations. Xenon is a relatively inert probe that would normally be found naturally in polymer or in NMR probe materials. There are two NMR active xenon isotopes, Xe-129 and Xe-131. The Xe atom has a very high polarizability, which makes it sensitive to the intracrystalline environment of polymers. Interactions between the Xe atoms and the host matrix perturb the Xe electron cloud, deshielding the nuclei, and thereby expanding the range of the observed NMR chemical shifts. This chemical shift range which may be as large as 5000 ppm, permits subtle structural and chemical effects to be studied with high sensitivity. The Xe(129)-NMR line shape has been found to vary in response to changes in the pore symmetry of the framework hosts line Zeolites and Clathrasil compounds. Before exposure to Xe gas, the PMR-15 samples were dried in a vacuum oven at 150 C for 48 hours. The samples were then exposed to Xe gas at 30 psi for 72 hours and sealed in glass tubes with 1 atmosphere of xenon gas. Xenon gas at 1 atmosphere was used to tune up the spectrometer and to set up the appropriate NMR parameters. A single Xe-129 line at 83.003498 Mhz (with protons at 300 Mhz) was observed for the gas. With the xenon charged PMR-15 samples, a second broader line is observed 190 ppm downfield from the gas line (also observed). The width of the NMR line from the Xe-129 absorbed in the polymer is at least partially due to the distribution of microvoid sizes. From the chemical shift (relative to the gas line) and the line width, we estimate the average void sizes to be 2.74 +/- 0.20 angstroms. Since Xe-129 has such a large chemical shift range (approximately 5000 ppm), we expect the chemical shift anisotropy to contribute to the line width (delta upsilon = 2.5 kHz).

Toy, James; Mattix, Larry

1995-01-01

166

Squid detected NMR and MRI at ultralow fields  

DOEpatents

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

Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

2006-05-30

167

SQUID detected NMR and MRI at ultralow fields  

DOEpatents

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

Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

2006-10-03

168

Squid detected NMR and MRI at ultralow fields  

DOEpatents

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

Clarke, John (Berkeley, CA); Pines, Alexander (Berkeley, CA); McDermott, Robert F. (Monona, WI); Trabesinger, Andreas H. (London, GB)

2008-12-16

169

Squid detected NMR and MRI at ultralow fields  

DOEpatents

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

Clarke, John (Berkeley, CA); McDermott, Robert (Louisville, CO); Pines, Alexander (Berkeley, CA); Trabesinger, Andreas Heinz (CH-8006 Zurich, CH)

2007-05-15

170

SQUID detected NMR and MRI at ultralow fields  

DOEpatents

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

Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

2005-04-26

171

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

172

NMR CHARACTERIZATIONS OF PROPERTIES OF HETEROGENEOUS MEDIA  

SciTech Connect

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

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

2005-01-01

173

Zeeman-Incremented Multiple-Quantum NMR  

NASA Astrophysics Data System (ADS)

A new method for performing multiple-quantum NMR experiments is described. Instead of incrementing the evolution period t1 in the conventional manner, t1 is kept fixed while the magnetic field is increased, successively. The method is illustrated using 19F spins in dipolar coupled 2,2-difluorotetrachloroethane, 1,1,1 -trichlorotrifluoroethane, and hexafluorobenzene, oriented in a nematic liquid crystal. It is demonstrated that Zeeman-incremented multiple-quantum NMR experiments give rise to simplified spectra in the multiple-quantum t1 domain, free from T2 decay. For example, in the case of hexafluorobenzene, just seven equally spaced peaks are observed, corresponding to ? m = ± 0, 1, . . . , 6.

Bowden, G. J.; Prandolini, M. J.; Pope, J. M.; Separovic, F.

174

Superconducting wires for NMR-application  

SciTech Connect

NMR analytical systems and MRI imaging magnets are now the very important area of NbTi based superconductors application. The characteristic features of these magnet systems are stability and high homogeneity of magnet fields. That is why the requirements for superconductors for that application include long unit length, low packing factor (P.F.) of superconducting alloy, high conductivity of matrix, precise dimensions of the filaments and the wire as a whole. Here, the results are presented on production of NbTi based conductors in copper matrix with wire diameters from 0.8 to 1.75 mm, filament numbers 12--42, filament diameters 55--130 {micro}m and packing factors 6.5--23%, with application in various NMR and MRI magnet systems. It is shown, that wire length could be tens of kilometers. Critical current, RRR and dielectric strength in all cases exceed requirements.

Salunin, N.I.; Plashkin, E.I.; Nikulenkov, E.V. [Bochvar All-Russia Scientific Research Inst. of Inorganic Materials, Moscow (Russian Federation)] [and others] [Bochvar All-Russia Scientific Research Inst. of Inorganic Materials, Moscow (Russian Federation); and others

1996-07-01

175

NMR studies of nucleic acid dynamics  

PubMed Central

Nucleic acid structures have to satisfy two diametrically opposite requirements; on one hand they have to adopt well-defined 3D structures that can be specifically recognized by proteins; on the other hand, their structures must be sufficiently flexible to undergo very large conformational changes that are required during key biochemical processes, including replication, transcription, and translation. How do nucleic acids introduce flexibility into their 3D structure without losing biological specificity? Here, I describe the development and application of NMR spectroscopic techniques in my laboratory for characterizing the dynamic properties of nucleic acids that tightly integrate a broad set of NMR measurements, including residual dipolar couplings, spin relaxation, and relaxation dispersion with sample engineering and computational approaches. This approach allowed us to obtain fundamental new insights into directional flexibility in nucleic acids that enable their structures to change in a very specific functional manner. PMID:24149218

Al-Hashimi, Hashim M.

2014-01-01

176

Some nitrogen-14 NMR studies in solids  

SciTech Connect

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

Pratum, T.K.

1983-11-01

177

NMR Characterizations of Properties of Heterogeneous Media  

SciTech Connect

The overall goal of this project was to develop reliable methods for resolving macroscopic properties important for describing the flow of one or more fluid phases in reservoirs from formation measurements. Completed the facilities to house our new NMR imager, the equipment has been delivered and installed. New experimental designs will provide for more reliable estimation of permeability distributions were evaluated. Designed and built a new core holder to incorporate one of the new experimental designs.

Watson, A. Ted; Phan, Jack; Uh, Jinsoo; Michalak, Rudi; Xue, Song

2003-01-28

178

Video: Proton Nuclear Magnetic Resonance (NMR)  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry, describes the basic principles of Nuclear Magnetic Resonance. This video is a good primer and would be very useful to supplement introductory lectures on NMR. The video covers the basic theory behind a 1H spectrum and goes through actually acquiring a spectrum. The top-off look of the instrument is useful and how the superconducting magnet is mounted. Running time for the video is 8:43.

179

Highly flexible pulse programmer for NMR applications  

NASA Technical Reports Server (NTRS)

A pulse generator for NMR application is described. Eighteen output channels are provided to allow use in single and double resonance experiments. Complex pulse sequences may be generated by loading instructions into a 256-word by 16-bit program memory. Features of the pulse generator include programmable time delays from 0.5 micros to 1000 s, branching and looping instructions, and the ability to be loaded and operated either manually or from a PDP-11/10 computer.

Dart, J.; Burum, D. P.; Rhim, W. K.

1980-01-01

180

?-NMR in II–VI semiconductors  

Microsoft Academic Search

?-active probe nuclei are implanted in nominally undoped ZnSe crystals. ?-radiation detected nuclear magnetic resonance (?-NMR)\\u000a studies are described for two different probe nuclei, 8Li and 12B. This way, the implantation behavior of two “opposite”dopants, one acceptor (Li) and one donor (B) can be characterized\\u000a by the same microscopic technique. Such characterizations are attempted in terms of the structure of

B. Ittermann; M. Füllgrabe; M. Heemeier; F. Kroll; F. Mai; K. Marbach; P. Meier; D. Peters; G. Welker; W. Geithner; S. Kappertz; S. Wilbert; R. Neugart; P. Lievens; U. Georg; M. Keim

2000-01-01

181

Protein Structure Determination Using Protein Threading and Sparse NMR Data  

SciTech Connect

It is well known that the NMR method for protein structure determination applies to small proteins and that its effectiveness decreases very rapidly as the molecular weight increases beyond about 30 kD. We have recently developed a method for protein structure determination that can fully utilize partial NMR data as calculation constraints. The core of the method is a threading algorithm that guarantees to find a globally optimal alignment between a query sequence and a template structure, under distance constraints specified by NMR/NOE data. Our preliminary tests have demonstrated that a small number of NMR/NOE distance restraints can significantly improve threading performance in both fold recognition and threading-alignment accuracy, and can possibly extend threading's scope of applicability from structural homologs to structural analogs. An accurate backbone structure generated by NMR-constrained threading can then provide a significant amount of structural information, equivalent to that provided by the NMR method with many NMR/NOE restraints; and hence can greatly reduce the amount of NMR data typically required for accurate structure determination. Our preliminary study suggests that a small number of NMR/NOE restraints may suffice to determine adequately the all-atom structure when those restraints are incorporated in a procedure combining threading, modeling of loops and sidechains, and molecular dynamics simulation. Potentially, this new technique can expand NMR's capability to larger proteins.

Crawford, O.H.; Einstein, J.R.; Xu, D.; Xu, Y.

1999-11-14

182

Development of Halbach magnet for portable NMR device  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) has enormous potential for various applications in industry as the on-line or at-line test/control device of process environments. Advantage of NMR is its non-destructive nature, because it does not require the measurement probe to have a contact with the tested media. Despite of the recent progress in this direction, application of NMR in industry is still very limited. This is related to the technical and analytical complications of NMR as a method, and high cost of NMR analyzers available at the market. However in many applications, NMR is a very useful technique to test various products and to monitor quantitatively industrial processes. Fortunately usually there is no need in a high-field superconducting magnets to obtain the high-resolution spectra with the detailed information on chemical shifts and coupling-constant. NMR analyzers are designed to obtain the relaxation parameters by measuring the NMR spectra in the time domain rather than in frequency domain. Therefore it is possible to use small magnetic field (and low frequency of 2-60 MHz) in NMR systems, based on permanent magnet technology, which are specially designed for specific at-line and on-line process applications. In this work we present the permanent magnet system developed to use in the portative NMR devices. We discuss the experimental parameters of the designed Halbach magnet system and compare them with results of theoretical modelling.

Do?an, N.; Topkaya, R.; Suba?i, H.; Yerli, Y.; Rameev, B.

2009-03-01

183

Automatic maximum entropy spectral reconstruction in NMR.  

PubMed

Developments in superconducting magnets, cryogenic probes, isotope labeling strategies, and sophisticated pulse sequences together have enabled the application, in principle, of high-resolution NMR spectroscopy to biomolecular systems approaching 1 megadalton. In practice, however, conventional approaches to NMR that utilize the fast Fourier transform, which require data collected at uniform time intervals, result in prohibitively lengthy data collection times in order to achieve the full resolution afforded by high field magnets. A variety of approaches that involve nonuniform sampling have been proposed, each utilizing a non-Fourier method of spectrum analysis. A very general non-Fourier method that is capable of utilizing data collected using any of the proposed nonuniform sampling strategies is maximum entropy reconstruction. A limiting factor in the adoption of maximum entropy reconstruction in NMR has been the need to specify non-intuitive parameters. Here we describe a fully automated system for maximum entropy reconstruction that requires no user-specified parameters. A web-accessible script generator provides the user interface to the system. PMID:17701276

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

2007-10-01

184

NMR Studies of Cartilage Dynamics, Diffusion, Degradation  

NASA Astrophysics Data System (ADS)

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

Huster, Daniel; Schiller, Jürgen; Naji, Lama; et al.

185

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

186

Strategies for overcoming linewidth limitations in quantitative petrophysical NMR measurements.  

PubMed

The simple pulse-acquire experiment has been used to evaluate the level of accuracy and precision achievable in NMR fluid saturation measurements for a range of rock core samples saturated with either brine or hydrocarbons. For a set of more than 70 cores measured at 0.66 T the mean error in the NMR measurement is only 0.35% porosity when the sample linewidths are less than 50 ppm. However, for a significant portion of cores, those with very broad NMR linewidths (> 50 ppm), difficulties associated with nonuniform excitation are encountered. The magnetic susceptibility difference between pore fluid and rock matrix translates into relatively broad NMR linewidths, and this feature of petrophysical samples is the major difficulty in performing quantitative NMR experiments. Numerical simulations are used to complement the experimental results in order to develop strategies for obtaining accurate NMR results with these difficult samples. PMID:8170322

Peyron, M; Pierens, G K; Lucas, A J; Hall, L D; Potter, G F; Stewart, R C; Phelps, D W

1994-01-01

187

Universal Quantitative NMR Analysis of Complex Natural Samples  

PubMed Central

Nuclear Magnetic Resonance (NMR) is a universal and quantitative analytical technique. Being a unique structural tool, NMR also competes with metrological techniques for purity determination and reference material analysis. In pharmaceutical research, applications of quantitative NMR (qNMR) cover mostly the identification and quantification of drug and biological metabolites. Offering an unbiased view of the sample composition, and the possibility to simultaneously quantify multiple compounds, qNMR has become the method of choice for metabolomic studies and quality control of complex natural samples such as foods, plants or herbal remedies, and biofluids. In this regard, NMR-based metabolomic studies, dedicated to both the characterization of herbal remedies and clinical diagnosis, have increased considerably. PMID:24484881

Simmler, Charlotte; Napolitano, José G.; McAlpine, James B.; Chen, Shao-Nong; Pauli, Guido F.

2013-01-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

189

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

PubMed

ADAPT-NMR (Assignment-directed Data collection Algorithm utilizing a Probabilistic Toolkit in NMR) supports automated NMR data collection and backbone and side chain assignment for [U-(13)C, U-(15)N]-labeled proteins. Given the sequence of the protein and data for the orthogonal 2D (1)H-(15)N and (1)H-(13)C planes, the algorithm automatically directs the collection of tilted plane data from a variety of triple-resonance experiments so as to follow an efficient pathway toward the probabilistic assignment of (1)H, (13)C, and (15)N signals to specific atoms in the covalent structure of the protein. Data collection and assignment calculations continue until the addition of new data no longer improves the assignment score. ADAPT-NMR was first implemented on Varian (Agilent) spectrometers [A. Bahrami, M. Tonelli, S.C. Sahu, K.K. Singarapu, H.R. Eghbalnia, J.L. Markley, PLoS One 7 (2012) e33173]. Because of broader interest in the approach, we present here a version of ADAPT-NMR for Bruker spectrometers. We have developed two AU console programs (ADAPT_ORTHO_run and ADAPT_NMR_run) that run under TOPSPIN Versions 3.0 and higher. To illustrate the performance of the algorithm on a Bruker spectrometer, we tested one protein, chlorella ubiquitin (76 amino acid residues), that had been used with the Varian version: the Bruker and Varian versions achieved the same level of assignment completeness (98% in 20 h). As a more rigorous evaluation of the Bruker version, we tested a larger protein, BRPF1 bromodomain (114 amino acid residues), which yielded an automated assignment completeness of 86% in 55 h. Both experiments were carried out on a 500 MHz Bruker AVANCE III spectrometer equipped with a z-gradient 5 mm TCI probe. ADAPT-NMR is available at http://pine.nmrfam.wisc.edu/ADAPT-NMR in the form of pulse programs, the two AU programs, and instructions for installation and use. PMID:24091140

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

2013-11-01

190

Structure Determination of Biological Macromolecules in Solution Using NMR spectroscopy  

Microsoft Academic Search

Abstract A detailed understanding of the function of a biological macromolecule,requires knowledge,of its three-dimensional structure. Most atomic-resolution structures of biological macromolecules have been solved either by x-ray diffraction in single crystals or by nuclear magnetic resonance (NMR) in solution. This review surveys the method,of NMR structure determination. First a brief introduction to NMR and its basic concepts is presented. The

Gerhard Wider

191

Assignments of RNase A by ADAPT-NMR and enhancer.  

PubMed

We report here backbone (1)H and (15)N assignments for ribonuclease A obtained by using ADAPT-NMR, a fully-automated approach for combined data collection, spectral analysis and resonance assignment. ADAPT-NMR was able to assign 98 % of the resonances with 93 % agreement with traditional data collection and assignment. Further refinement of the automated results with ADAPT-NMR enhancer led to complete (100 %) assignments with 96 % agreement with assignments by the traditional approach. PMID:24619609

Tonelli, Marco; Eller, Chelcie H; Singarapu, Kiran K; Lee, Woonghee; Bahrami, Arash; Westler, William M; Raines, Ronald T; Markley, John L

2015-04-01

192

Fluid-Rock Characterization and Interactions in NMR Well Logging  

SciTech Connect

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

Hirasaki, George J.; Mohanty, Kishore K.

2003-02-10

193

Rotational Doppler Effect and Barnett Field in Spinning NMR  

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

194

Liquid Domains in Vesicles Investigated by NMR and Fluorescence Microscopy  

Microsoft Academic Search

We use 2H-NMR, 1H-MAS NMR, and fluorescence microscopy to detect immiscibility in three particular phospholipid ratios mixed with 30% cholesterol: 2:1 DOPC\\/DPPC, 1:1 DOPC\\/DPPC, and 1:2 DOPC\\/DPPC. Large-scale (?160nm) phase separation into liquid-ordered (Lo) and liquid-crystalline (L?) phases is observed by both NMR and fluorescence microscopy. By fitting superimposed 2H-NMR spectra, we quantitatively determine that the Lo phase is strongly

S. L. Veatch; I. V. Polozov; K. Gawrisch; S. L. Keller

2004-01-01

195

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

SciTech Connect

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

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

2014-06-20

196

Lithium Polymer Electrolytes and Solid State NMR  

NASA Technical Reports Server (NTRS)

Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for participation on a variety of other projects, including aero-gels and carbon graphite mat en als. The goals of the polymer electrolyte research are to improve the physical properties of the polymers. This includes improving conductivity, durability, and expanding the temperature range over which it is effective. Currently, good conductivity is only present at high temperatures. My goals are to experiment with different arrangements of rods and coils to achieve these desirable properties. Some of my experiments include changing the number of repeat units in the polymer, the size of the diamines, and the types of coil. Analysis of these new polymers indicates improvement in some properties, such as lower glass transition temperature; however, they are not as flexible as desired. With further research we hope to produce polymers that encompass all of these properties to a high degree.

Berkeley, Emily R.

2004-01-01

197

Touch NMR: An NMR Data Processing Application for the iPad  

ERIC Educational Resources Information Center

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

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

2014-01-01

198

Algorithmic Cooling in Liquid State NMR  

E-print Network

Algorithmic cooling is a method that employs thermalization to increase the qubits' purification level, namely it reduces the qubit-system's entropy. We utilized gradient ascent pulse engineering (GRAPE), an optimal control algorithm, to implement algorithmic cooling in liquid state nuclear magnetic resonance. Various cooling algorithms were applied onto the three qubits of 13C2-trichloroethylene, cooling the system beyond Shannon's entropy bound in several different ways. For example, in one experiment a carbon qubit was cooled by a factor of 4.61. This work is a step towards potentially integrating tools of NMR quantum computing into in vivo magnetic resonance spectroscopy.

Yosi Atia; Yuval Elias; Tal Mor; Yossi Weinstein

2014-11-17

199

NMR Characterizations of Properties of Heterogeneous Media  

SciTech Connect

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

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

2003-01-28

200

NMR used for Saudi crude asphaltenes  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopy with proton (/sup 1/H) and carbon 13 (/sup 13/C) has been used to determine the structural characteristics of asphaltenes from four commercial Saudi Arabian crude oils. These characteristics are important to refiners that have deep conversion processes to determine yields from the residual fractions of the Saudi crudes, and to determine the operating parameters of the process units. The spectra obtained give some structural similarities among the crude oils, as well as some differences. Values of various structural parameters have been tabulated from the spectra.

Hasan, M.U.; Siddiqui, M.N.; Arab, M.

1988-02-08

201

Analysis of multiple pulse NMR in solids  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

202

MULTIPLE-QUANTUM NMR IN SOLIDS  

SciTech Connect

Time domain multiple-quantum (MQ) nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for spectral simplification and for providing new information on molecular dynamics. In this thesis, applications of MQ NMR are presented and show distinctly the advantages of this method over the conventional single-quantum NMR. Chapter 1 introduces the spin Hamiltonians, the density matrix formalism and some basic concepts of MQ NMR spectroscopy. In chapter 2, {sup 14}N double-quantum coherence is observed with high sensitivity in isotropic solution, using only the magnetization of bound protons. Spin echoes are used to obtain the homogeneous double-quantum spectrum and to suppress a large H{sub 2}O solvent signal. Chapter 3 resolves the main difficulty in observing high MQ transitions in solids. Due to the profusion of spin transitions in a solid, individual lines are unresolved. Excitation and detection of high quantum transitions by normal schemes are thus difficult. To ensure that overlapping lines add constructively and thereby to enhance sensitivity, time-reversal pulse sequences are used to generate all lines in phase. Up to 22-quantum {sup 1}H absorption in solid adamantane is observed. A time dependence study shows an increase in spin correlations as the excitation time increased. In chapter 4, a statistical theory of MQ second moments is developed for coupled spins of spin I = 1/2. The model reveals that the ratio of the average dipolar coupling to the rms value largely determines the dependence of second moments on the number of quanta. The results of this model are checked against computer-calculated and experimental second moments, and show good agreement. A simple scheme is proposed in chapter 5 for sensitivity improvement in a MQ experiment. The scheme involves acquiring all of the signal energy available in the detection period by applying pulsed spinlocking and sampling between pulses. Using this technique on polycrystalline adamantane, a large increase in sensitivity is observed. Correlation of motion of two interacting methyl groups is the subject of chapter 6. This system serves as a model for the study of hindered internal motion. Because the spin system is small and the motions are well-defined, the calculations involved are tractable. Group theory appropriate for nonrigid molecules is used to treat the change in the Hamiltonian as the methyl groups transit from correlated to uncorrelated motion. Results show that the four-quantum order alone is sufficient to distinguish between the two motions.

Yen, Y-S.

1982-11-01

203

NMR measurements of intracellular ions in hypertension  

NASA Astrophysics Data System (ADS)

The NMR methods for the measurement of intracellular free Na+, K+, Mg2+, Ca2+, and H+ are introduced. The recent literature is then presented showing applications of these methods to cells and tissues from hypertensive animal model systems, and humans with essential hypertension. The results support the hypothesis of consistent derangement of the intracellular ionic environment in hypertension. The theory that this derangement may be a common link in the disease states of high blood pressure and abnormal insulin and glucose metabolism, which are often associated clinically, is discussed.

Veniero, Joseph C.; Gupta, R. K.

1993-08-01

204

Pulsed Gradient Spin-Echo NMR  

NASA Astrophysics Data System (ADS)

Translational diffusion (also referred to as self-diffusion, Brownian motion, or random walks) plays a vital role in all sorts of molecular dynamics in biological systems (e.g., ligand-DNA interactions, lipid-macromolecule interactions, and macromolecule aggregation). Due to its non-invasive nature, pulsed gradient spin-echo (PGSE) NMR has become a method of choice for the study of molecular dynamics and structural details of biological systems [1, 2]; in combination with magnetic resonance imaging (MRI), it allows (localised) in vivo diffusion measurements.

Zheng, Gang; Krause-Heuer, Anwen M.; Price, William S.

205

Kurt Wüthrich and NMR of biological macromolecules.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy is the only experimental technique that can determine the structures and dynamics of biological macromolecules and their complexes in solution and with atomic resolution. The award of the 2002 Nobel Prize in Chemistry to Kurt Wüthrich of the Swiss Federal Institute of Technology and The Scripps Research Institute honors his pioneering efforts in developing and applying this technique. Wüthrich shared the prize with John B. Fenn and Koichi Tanaka, who were recognized for the development of ionization methods for the analysis of proteins using mass spectrometry. PMID:12467565

Palmer, Arthur G; Patel, Dinshaw J

2002-12-01

206

Measuring Protein Concentrations by NMR Spectroscopy Gerhard Wider* and Lars Dreier  

E-print Network

Measuring Protein Concentrations by NMR Spectroscopy Gerhard Wider* and Lars Dreier Contribution concentrations directly in the NMR tube. In principle, NMR spectroscopy would be very well suited to measure

Wider, Gerhard

207

CHARACTERIZATION OF METABOLITES IN SMALL FISH BIOFLUIDS AND TISSUES BY NMR SPECTROSCOPY  

EPA Science Inventory

Nuclear magnetic resonance (NMR) spectroscopy has been utilized for assessing ecotoxicity in small fish models by means of metabolomics. Two fundamental challenges of NMR-based metabolomics are the detection limit and characterization of metabolites (or NMR resonance assignments...

208

Characterizing carbohydrate-protein interactions by NMR  

PubMed Central

Interactions between proteins and soluble carbohydrates and/or surface displayed glycans are central to countless recognition, attachment and signaling events in biology. The physical chemical features associated with these binding events vary considerably, depending on the biological system of interest. For example, carbohydrate-protein interactions can be stoichiometric or multivalent, the protein receptors can be monomeric or oligomeric, and the specificity of recognition can be highly stringent or rather promiscuous. Equilibrium dissociation constants for carbohydrate binding are known to vary from micromolar to millimolar, with weak interactions being far more prevalent; and individual carbohydrate binding sites can be truly symmetrical or merely homologous, and hence, the affinities of individual sites within a single protein can vary, as can the order of binding. Several factors, including the weak affinities with which glycans bind their protein receptors, the dynamic nature of the glycans themselves, and the non-equivalent interactions among oligomeric carbohydrate receptors, have made NMR an especially powerful tool for studying and defining carbohydrate-protein interactions. Here we describe those NMR approaches that have proven to be the most robust in characterizing these systems, and explain what type of information can (or cannot) be obtained from each. Our goal is to provide to the reader the information necessary for selecting the correct experiment or sets of experiments to characterize their carbohydrate-protein interaction of interest. PMID:23784792

Bewley, Carole A.; Shahzad-ul-Hussan, Syed

2013-01-01

209

NMR crystallography: the use of chemical shifts  

NASA Astrophysics Data System (ADS)

Measurements of chemical shifts obtained from magic-angle spinning NMR spectra (together with quantum mechanical computations of shielding) can provide valuable information on crystallography. Examples are given of the determination of crystallographic asymmetric units, of molecular symmetry in the solid-state environment, and of crystallographic space group assignment. Measurements of full tensor components for 199Hg have given additional coordination information. The nature of intermolecular hydrogen bonding in cortisone acetate polymorphs and solvates is obtained from chemical shift information, also involving measurement of the full tensor parameters. The resulting data have been used as restraints, built into the computation algorithm, in the analysis of powder diffraction patterns to give full crystal structures. A combination of quantum mechanical computation of shielding and measurement of proton chemical shifts (obtained by high-speed MAS) leads to the determination of the position of a proton in an intermolecular hydrogen bond. A recently-developed computer program specifically based on crystallographic repetition has been shown to give acceptable results. Moreover, NMR chemical shifts can distinguish between static and dynamic disorder in crystalline materials and can be used to determine modes and rates of molecular exchange motion.

Harris, Robin K.

2004-10-01

210

The D0 solenoid NMR magnetometer  

SciTech Connect

A field monitoring system for the 2 Tesla Solenoid of the D0 detector is described. It is comprised of a very small NMR probe cabled to a DSP based signal processing board. The design magnetic field range is from 1.0 to 2.2 Tesla, corresponding to an RF frequency range of 42.57 to 93.67 MHz. The desired an accuracy is one part in 10{sup 5}. To minimize material in the interaction region of the D0 detector, the overall thickness of the NMR probe is 4 mm, including its mounting plate, and its width is 10 mm. To minimize cable mass, 4mm diameter IMR-100A cables are used for transmitting the RF signals from a nearby patch panel 25 meters to each of four probes mounted within the bore of the solenoid. RG213U cables 45 meters long are used to send the RF from the movable counting house to the patch panel. With this setup, the detector signal voltage at the moving counting room is in the range of 250-400 mV.

Sten Uldall Hansen Terry Kiper, Tom Regan, John Lofgren et al.

2002-11-20

211

NMR studies of actinide oxides - A review  

NASA Astrophysics Data System (ADS)

In this paper, we offer a brief review of the ground-state properties of the cubic oxides AnO2, where An=U, Np, Pu and Am, as revealed mainly by NMR studies of the 17O2- ligand. For PuO2, where the ground state is a nonmagnetic singlet eigenstate of the cubic crystal field, only the 239Pu has been studied, in a recent breakthrough observation of this elusive isotope [1]. For UO2 and NpO2, the former has an exotic four-sublattice antiferromagnetic (AFM) ground state, while the latter has the first multipolar ground state to be identified among actinide compounds, namely a mixture of octupolar and rank 5 (triakontadipolar) order. On the other hand AmO2, even with the longest-lived isotope 243Am, becomes disordered so quickly from radiation self-damage that its ground state in a recent study was simply a spin glass, while the actual ground state of the cubic crystalline compound remains obscured by this experimental problem. The emphasis throughout is on how 17O NMR studies complement other experimental data to confirm and verify the known exotic magnetic ground states of AnO2 systems. xml:lang="fr"

Walstedt, Russell E.; Tokunaga, Yo; Kambe, Shinsaku

2014-08-01

212

NMR investigation of iron-based superconductors  

NASA Astrophysics Data System (ADS)

We report NMR investigation of the electronic properties of iron-based superconductors with primary focus on the 11 (FeSe) and 122 (Co-doped BaFe2As2) systems. From the ^77Se and ^75As NMR Knight shift K measurements, we will deduce the intrinsic temperature and concentration dependences of the uniform spin susceptibility, ?spin, in these systems. We will also demonstrate the evolution of antiferromagnetic spin fluctuations (AFSF) as a function of pressure (in FeSe) or the doping level (in Ba[Fe1-xCox]2As2). Our results show that the optimal superconducting phase exists in close proximity with SDW order; superconductivity sets in only after AFSF grow toward Tc. This work was carried out in collaboration with F.L. Ning and K. Ahilan (McMaster), T. McQueen and R.J. Cava (Princeton), A.S. Sefat, M.A. McGuire, B. C. Sales, and D. Mandrus (Oak Ridge), P. Cheng, B. Shen, and H.-H Wen (Chinese Academy of Sciences). The work at McMaster was supported by NSERC, CIFAR, and CFI.

Imai, Takashi

2010-03-01

213

NMR measurements in solutions of dialkylimidazolium haloaluminates  

SciTech Connect

{sup 27}Al and {sup 35}Cl NMR spectra of AlCl{sub 3}-1-ethyl-3-methyl imidazolium chloride (EMIC) melts were measured for initial compositions ranging from 50 to 67 mol % AlCl{sub 3} at various temperatures. It was shown by changing the preaquisition delay time (DE value) that the dominant aluminum species are AlCl{sub 4}{sup {minus}} in the melt formed by mixing 50 mol % with EMIC and Al{sub 2}Cl{sub 7}{sup {minus}} in the 67 mol % AlCl{sub 3} melt. In the equimolar mixture, the chemical shift of {sup 27}Al NMR spectrum is 103.28 ppm and the line width is 22.83Hz. In the 67 mol % AlCl{sub 3} mixture, the chemical shift is 103.41 ppm and the line width is 2624Hz. A third species observed at 97 ppm in the {sup 27}Al spectra for the 55 and 60 mol % AlCl{sub 3} mixtures is identified to be a product of the reaction with residual water. The relaxation rates for each species in the melts were determined.

Takahashi, S.; Saboungi, M.L.; Klingler, R.J.; Chen, M.J.; Rathke, J.W.

1992-06-01

214

Protein Structure Determination using Protein Threading and Sparse NMR Data  

Microsoft Academic Search

It zs well known that the NMR method for protein struc- ture determinatwn apphes to small proteins and that zts effectweness decreases very rapidly as the molecular weight increases beyond about 30 kD. We have recently developed a method for protein structure determmatwn that can fully utilize partzal NMR data as calculation constraints. The core of the method is a

Ying Xu; Dong Xu; Oakley H. Crawford; J. Ralph Einstein

2000-01-01

215

PROTEIN STRUCTURAL ANALYSIS FROM SOLID STATE NMR DERIVED ORIENTATIONAL CONSTRAINTS  

E-print Network

of a molecule is solved using distance constraints, in solid state NMR, the structure is solved usingPROTEIN STRUCTURAL ANALYSIS FROM SOLID STATE NMR DERIVED ORIENTATIONAL CONSTRAINTS J. R. QUINE provides a great structural analysis problem. Several approaches to this problem have been made in the past

Aluffi, Paolo

216

An NMR microscopy study of water absorption in cork  

Microsoft Academic Search

NMR Microscopy is used to measure the imbibition of water into natural cork, extractives-free cork and desuberised cork. The results clearly indicate that suberin is the key constituent which determines the ability of cork to resist water uptake. Furthermore, a particular suberin with distinct spectral properties as viewed by 13C NMR is shown to be the component responsible for cork

A. M. Gil; M. H. Lopes; C. Pascoal Neto; P. T. Callaghan

2000-01-01

217

Chapter 12 NMR studies of FCC feeds, catalysts and coke  

Microsoft Academic Search

NMR has become an indispensable tool for characterizing a variety of complex materials, includingheavy petroleum fractions, catalysts and coke. Determination of average molecular parameter by NMR is useful for the analysis of complex hydrocarbons like coal liquids, heavy oils, synthetic oils and high boiling petroleum fractions. This not only gives a brief idea of the molecules present but can also

Babita Behera; Siddharth S. Ray; I. D. Singh

2007-01-01

218

Nuclear magnetic resonance (NMR) studies of homeopathic solutions  

Microsoft Academic Search

The efficacy of homeopathy is controversial. Nuclear magnetic resonance (NMR) has been used to study homeopathic solutions, showing provocative results. We examined the reproducibility of one of the allegedly positive studies.1H NMR spectra were recorded for Sulphur D4, diluted and succussed up to D30 (called potentization) at two different frequencies (300 and 500 MHz). The Sulphur solution had been potentiated

S Aabel; S Fossheim; F Rise

2001-01-01

219

AB3 Proton NMR Using Tensor Algebra Frank Rioux  

E-print Network

AB3 Proton NMR Using Tensor Algebra Frank Rioux Professor Emeritus of Chemistry CSB|SJU The purpose of this tutorial is to calculate the NMR spectrum of a four proton AB3 system in Hz) are for the AB3 proton system 1,1dichloroethane at 60 MHz. A 350.0 B 120.0 Jab 10.00 Hamiltonian

Rioux, Frank

220

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret.

221

Liquid Domains in Vesicles Investigated by NMR and Fluorescence Microscopy  

PubMed Central

We use 2H-NMR, 1H-MAS NMR, and fluorescence microscopy to detect immiscibility in three particular phospholipid ratios mixed with 30% cholesterol: 2:1 DOPC/DPPC, 1:1 DOPC/DPPC, and 1:2 DOPC/DPPC. Large-scale (?160 nm) phase separation into liquid-ordered (Lo) and liquid-crystalline (L?) phases is observed by both NMR and fluorescence microscopy. By fitting superimposed 2H-NMR spectra, we quantitatively determine that the Lo phase is strongly enriched in DPPC and moderately enriched in cholesterol. Tie-lines estimated at different temperatures and membrane compositions are based on both 2H-NMR observations and a previously published ternary phase diagram. 2H- and 1H-MAS NMR techniques probe significantly smaller length scales than microscopy experiments (submicron versus micron-scalp), and complex behavior is observed near the miscibility transition. Fluorescence microscopy of giant unilamellar vesicles shows micrometer-scale domains below the miscibility transition. In contrast, NMR of multilamellar vesicles gives evidence for smaller (?80 nm) domains just below the miscibility transition, whereas large-scale demixing occurs at a lower temperature, Tlow. A transition at Tlow is also evident in fluorescence microscopy measurements of the surface area fraction of ordered phase in giant unilamellar vesicles. Our results reemphasize the complex phase behavior of cholesterol-containing membranes and provide a framework for interpreting 2H-NMR experiments in similar membranes. PMID:15111407

Veatch, S. L.; Polozov, I. V.; Gawrisch, K.; Keller, S. L.

2004-01-01

222

NMR CHARACTERIZATION OF DIHYDROSTERCULIC ACID AND ITS METHYL ESTER  

Technology Transfer Automated Retrieval System (TEKTRAN)

Dihydrosterculic acid (2-octyl cyclopropaneoctanoic acid) and its methyl ester were selected for 1H- and 13C-NMR analysis as compounds representative of cyclopropane fatty acids. The 500 MHz 1H-NMR spectra acquired with CDCl3 as solvent show two individual peaks at -0.30 and 0.60 ppm for the methyl...

223

Structure calculation, refinement and validation using CcpNmr Analysis  

PubMed Central

CcpNmr Analysis provides a streamlined pipeline for both NMR chemical shift assignment and structure determination of biological macromolecules. In addition, it encompasses tools to analyse the many additional experiments that make NMR such a pivotal technique for research into complex biological questions. This report describes how CcpNmr Analysis can seamlessly link together all of the tasks in the NMR structure-determination process. It details each of the stages from generating NMR restraints [distance, dihedral, hydrogen bonds and residual dipolar couplings (RDCs)], exporting these to and subsequently re-importing them from structure-calculation software (such as the programs CYANA or ARIA) and analysing and validating the results obtained from the structure calculation to, ultimately, the streamlined deposition of the completed assignments and the refined ensemble of structures into the PDBe repository. Until recently, such solution-structure determination by NMR has been quite a laborious task, requiring multiple stages and programs. However, with the new enhancements to CcpNmr Analysis described here, this process is now much more intuitive and efficient and less error-prone. PMID:25615869

Skinner, Simon P.; Goult, Benjamin T.; Fogh, Rasmus H.; Boucher, Wayne; Stevens, Tim J.; Laue, Ernest D.; Vuister, Geerten W.

2015-01-01

224

Chemical Equilibrium in Supramolecular Systems as Studied by NMR Spectrometry  

ERIC Educational Resources Information Center

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

Gonzalez-Gaitano, Gustavo; Tardajos, Gloria

2004-01-01

225

Studying the pore space of cuttings by NMR and ?CT  

NASA Astrophysics Data System (ADS)

Evaluating the formation quality by deriving porosity, pore size, and permeability from cuttings instead of drill cores is a promising and challenging field of research established in the past decade. Challenges with cuttings are their small and irregular size rendering them unsuitable for e.g. standard permeability measurements. Permeability can be estimated from nuclear magnetic resonance (NMR) measurements. NMR measurements on cuttings are especially challenging 1) because the total NMR signal is very low due to small sample sizes and 2) because the high ratio of outer surface to volume leads to a significant contribution of interstitial water to the NMR signal, which thus distorts the informative NMR signal from within the pore space. The aim of the study is to evaluate the use of NMR in combination with micro-computed tomography (?CT) as a method to determine the pore space characteristics of small drill cuttings from the Bückeberg Formation (German Wealden). After accurate removal of interstitial water and a CT based sorting, it was possible to measure NMR signals representative for the individual pore sizes. The representiveness of the measured values was verified by simulations of the NMR signals in pore spaces determined via ?CT. Porosity, relaxation time distributions, and permeability were calculated for cuttings assemblages with large, medium, small, and very small pores.

Hübner, Wiete

2014-05-01

226

Probe for high resolution NMR with sample reorientation  

DOEpatents

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

Pines, Alexander (Berkeley, CA); Samoson, Ago (Tallinn, SU)

1990-01-01

227

Probe for high resolution NMR with sample reorientation  

DOEpatents

An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions are zero. 8 figs.

Pines, A.; Samoson, A.

1990-02-06

228

Interface between Microbiology and Structural Biology as viewed by NMR  

E-print Network

1 Interface between Microbiology and Structural Biology as viewed by NMR Muriel DELEPIERRE, Anne2007 Author manuscript, published in "Research in Microbiology 152, 8 (2001) 697-705" #12;2 Abstract in microbiology. 1 Introduction NMR and X-ray crystallography are the two most powerful tools available

Paris-Sud XI, Université de

229

Fluid-Rock Characterization and Interactions in NMR Well Logging  

SciTech Connect

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

George J. Hirasaki; Kishore K. Mohanty

2005-09-05

230

Solid-State NMR Investigation of Block Copolymer Electrolyte Dynamics  

E-print Network

Solid-State NMR Investigation of Block Copolymer Electrolyte Dynamics D. J. Harris,*, T. J in solid polymer electrolytes. The electrolytic properties of lithium salt-doped poly(ethyl- ene oxide of block copolymers, we have studied these systems by solid-state nuclear magnetic resonance (NMR) line

Sadoway, Donald Robert

231

NMR-Metabolic Methodology in the Study of GM Foods  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 1H NMR methodology used in the study of genetically modified (GM) foodstuff is discussed. The study of transgenic lettuce (Lactuca sativa cv "Luxor") over-expressing the KNAT1 gene from Arabidopsis is presented as a novel study-case. The 1H NMR metabolic profiling was carried out. Twenty-two wat...

232

NMR-0Fessler, Univ. of Michigan Nuclear Magnetic Resonance Imaging  

E-print Network

NMR-0Fessler, Univ. of Michigan Nuclear Magnetic Resonance Imaging Jeffrey A. Fessler EECS Department The University of Michigan NSS-MIC: Fundamentals of Medical Imaging Oct. 20, 2003 #12;NMR-1Fessler, Univ. of Michigan Outline · Background · Basic physics · 4 magnetic fields · Bloch equation

Fessler, Jeffrey A.

233

Web Spectra: Problems in NMR and IR spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13 C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy.

Merlic, Craig A.

234

Functional groups identified by solid state 13C NMR spectroscopy  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

235

Porous media characterization by PFG and IMFG NMR  

NASA Astrophysics Data System (ADS)

Fully and partially filled with tridecane quartz sand was studied by different NMR techniques. The set of NMR experiments was carried out to obtain information about porous media geometry and fluid localization in it in case of partially filled porous space. The study was done using three NMR approaches: pulse field gradient NMR (PFG NMR), DDif experiment and tau-scanning experiment. The possibility to use all three approaches to study porous media properties even at the high resonance frequency is shown together with complementarity of the given by them information. Thus, first two approaches give information about porous sizes and geometry, at the same time tau-scanning experiment allows us to obtain information about distribution of internal magnetic field gradients in the porous space and draw conclusions about fluid localization in it.

Mutina, Albina R.; Skirda, Vladimir D.

2007-09-01

236

Porous media characterization by PFG and IMFG NMR.  

PubMed

Fully and partially filled with tridecane quartz sand was studied by different NMR techniques. The set of NMR experiments was carried out to obtain information about porous media geometry and fluid localization in it in case of partially filled porous space. The study was done using three NMR approaches: pulse field gradient NMR (PFG NMR), DDif experiment and tau-scanning experiment. The possibility to use all three approaches to study porous media properties even at the high resonance frequency is shown together with complementarity of the given by them information. Thus, first two approaches give information about porous sizes and geometry, at the same time tau-scanning experiment allows us to obtain information about distribution of internal magnetic field gradients in the porous space and draw conclusions about fluid localization in it. PMID:17643327

Mutina, Albina R; Skirda, Vladimir D

2007-09-01

237

Earth’s field NMR flow meter: Preliminary quantitative measurements  

NASA Astrophysics Data System (ADS)

In this paper we demonstrate the use of Earth’s field NMR (EF NMR) combined with a pre-polarising permanent magnet for measuring fast fluid velocities. This time of flight measurement protocol has a considerable history in the literature; here we demonstrate that it is quantitative when employing the Earth’s magnetic field for signal detection. NMR signal intensities are measured as a function of flow rate (0-1 m/s) and separation distance between the permanent magnet and the EF NMR signal detection. These data are quantitatively described by a flow model, ultimately featuring no free parameters, that accounts for NMR signal modulation due to residence time inside the pre-polarising magnet, between the pre-polarising magnet and the detection RF coil and inside the detection coil respectively. The methodology is subsequently demonstrated with a metallic pipe in the pre-polarising region.

Fridjonsson, Einar O.; Stanwix, Paul L.; Johns, Michael L.

2014-08-01

238

Mobile NMR for porosity analysis of drill core sections  

NASA Astrophysics Data System (ADS)

We apply a novel mobile nuclear magnetic resonance (NMR) scanning system, the NMR-MOUSE® (NMR-MOUSE (Nuclear Magnetic Resonance Mobile Universal Surface Explorer) is a registered trademark of RWTH Aachen University), for measuring porosity of geological drill core sections. The NMR-MOUSE® is used for transverse relaxation measurements on water-saturated core sections using a CPMG sequence with a short echo time. A regularized Laplace-transform analysis by the UPEN program yields the distribution of transverse relaxation times. The signal amplitudes and the distribution integrals correlate directly with the porosity of the cores, in spite of the influence of diffusion in the strong field gradient of the NMR-MOUSE®, which is discussed. The method is particularly attractive because it neither requires a volume calibration nor the samples to be machined to fit the coil, and because the device is mobile and particularly attractive for field use such as on logging platforms and research vessels.

Blümich, Bernhard; Anferova, Sofia; Pechnig, Renate; Pape, Hansgeorg; Arnold, Juliane; Clauser, Christoph

2004-09-01

239

A review of blind source separation in NMR spectroscopy.  

PubMed

Fourier transform is the data processing naturally associated to most NMR experiments. Notable exceptions are Pulse Field Gradient and relaxation analysis, the structure of which is only partially suitable for FT. With the revamp of NMR of complex mixtures, fueled by analytical challenges such as metabolomics, alternative and more apt mathematical methods for data processing have been sought, with the aim of decomposing the NMR signal into simpler bits. Blind source separation is a very broad definition regrouping several classes of mathematical methods for complex signal decomposition that use no hypothesis on the form of the data. Developed outside NMR, these algorithms have been increasingly tested on spectra of mixtures. In this review, we shall provide an historical overview of the application of blind source separation methodologies to NMR, including methods specifically designed for the specificity of this spectroscopy. PMID:25142734

Toumi, Ichrak; Caldarelli, Stefano; Torrésani, Bruno

2014-08-01

240

Membrane Protein Structure and Dynamics from NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

We review the current state of membrane protein structure determination using solid-state nuclear magnetic resonance (NMR) spectroscopy. Multidimensional magic-angle-spinning correlation NMR combined with oriented-sample experiments has made it possible to measure a full panel of structural constraints of membrane proteins directly in lipid bilayers. These constraints include torsion angles, interatomic distances, oligomeric structure, protein dynamics, ligand structure and dynamics, and protein orientation and depth of insertion in the lipid bilayer. Using solid-state NMR, researchers have studied potassium channels, proton channels, Ca2+ pumps, G protein-coupled receptors, bacterial outer membrane proteins, and viral fusion proteins to elucidate their mechanisms of action. Many of these membrane proteins have also been investigated in detergent micelles using solution NMR. Comparison of the solid-state and solution NMR structures provides important insights into the effects of the solubilizing environment on membrane protein structure and dynamics.

Hong, Mei; Zhang, Yuan; Hu, Fanghao

2012-05-01

241

The virtual NMR spectrometer: a computer program for efficient simulation of NMR experiments involving pulsed field gradients.  

PubMed

This paper presents a software program, the Virtual NMR Spectrometer, for computer simulation of multichannel, multidimensional NMR experiments on user-defined spin systems. The program is capable of reproducing most features of the modern NMR experiment, including homo- and heteronuclear pulse sequences, phase cycling, pulsed field gradients, and shaped pulses. Two different approaches are implemented to simulate the effect of pulsed field gradients on coherence selection, an explicit calculation of all coherence transfer pathways, and an effective approximate method using integration over multiple positions in the sample. The applications of the Virtual NMR Spectrometer are illustrated using homonuclear COSY and DQF COSY experiments with gradient selection, heteronuclear HSQC, and TROSY. The program uses an intuitive graphical user interface, which resembles the appearance and operation of a real spectrometer. A translator is used to allow the user to design pulse sequences with the same programming language used in the actual experiment on a real spectrometer. The Virtual NMR Spectrometer is designed as a useful tool for developing new NMR experiments and for tuning and adjusting the experimental setup for existing ones prior to running costly NMR experiments, in order to reduce the setup time on a real spectrometer. It will also be a useful aid for learning the general principles of magnetic resonance and contemporary innovations in NMR pulse sequence design. PMID:10910695

Nicholas, P; Fushman, D; Ruchinsky, V; Cowburn, D

2000-08-01

242

Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging  

DOEpatents

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Fukushima, E.; Roeder, S.B.W.; Assink, R.A.; Gibson, A.A.V.

1984-01-01

243

NMR assignments of PI3-SH3 domain aided by protonless NMR spectroscopy.  

PubMed

We report here the near complete assignments of native bovine PI3-SH3 domain, which has been a model system for protein folding, misfolding and amyloid fibril formation. The use of (13)C-detected protonless NMR spectroscopy is instrumental in assigning the spin system of the proline residue at the C-terminus in addition to the missing resonances in proton-based NMR spectra due to rapid solvent exchange. It also helps assign the resonances of all three proline amine nitrogen nuclei, which are underrepresented in the database. Comparison of the backbone (13)C resonances of PI3-SH3 in its native and amyloid fibril states shows that the aggregation of PI3-SH3 is accompanied by major conformational rearrangements. PMID:23832674

Hsu, Shang-Te Danny

2014-10-01

244

NMR solvent peak suppression by nonlinear excitation  

NASA Astrophysics Data System (ADS)

Most existing NMR solvent peak suppression sequences provide a satisfactory dependence of the intensity of excited signals on frequency but poor phase characteristics. In practice this leads to spectral distortions which generally become more severe as the frequency selectivity of the sequence is increased. However, it is shown that by working well outside the linear response regime, excitation schemes which combine high frequency selectivity with good phase properties may be devised. Sequences of six rectangular radio-frequency pulses were discovered using a combination of coherent averaging theory to treat the near-resonant behavior and numerical simulation further from resonance. Extensive use of symmetry greatly simplifies both the coherent averaging calculations and the numerical simulations. The new pulse sequences have been given the acronym NERO (nonlinear excitation rejecting on-resonance). Experimental spectra of an enzyme in dilute aqueous solution are shown.

Levitt, Malcolm H.

1988-03-01

245

Superconducting wire for NMR-tomography  

SciTech Connect

The paper discusses the fabrication of Nb-Ti base superconducting wires having the superconductor packing factor of 15-20% and superconducting filaments 70-80 {mu}m dia. Three methods of precursor fabrication were tried. The NbTi-50 alloy base superconducting wire was fabricated to be used for the magnet system of a NMR-tomograph; the wire diameter is 0.85 mm; the packing factor is 16%; the maximum length of a single piece is 29 km{sub 2}. The critical current density is 6.1 {times} 10{sup 5} A/cm{sup 2} in the magnetic field of 1 T. The paper also presents the superconducting properties of similar wire on the NbTi-55 alloy base.

Filkin, V.Y.; Plashkin, E.I.; Salunin, N.I.; Morozova, T.A.; Zelenskiy, G.K.; Vlasova, L.V.; Drobyshev, V.A.; Zinovev, V.G.; Yakovlev, B.V. (All-Union Scientific and Research Inst. of Inorganic Materials, 123060 Moscow (SU))

1992-01-01

246

?-NMR study of boron in diamond  

NASA Astrophysics Data System (ADS)

A ?-NMR study of 12B implanted in diamond was performed in order to investigate the implantation sites and the defects. The maintained polarization of 12B was measured by use of widely modulated rf around the Larmor frequency (? = ? L ± 200 kHz) as a function of temperature from 160 K to 320 K. The observed polarization was found to be almost constant at about 0.9 % in this temperature range. The initial polarization for this system was obtained as about 8.1 %. Therefore about 10 % of the implanted 12B maintained its polarization in this frequency range. Conversely, about 90 % of the implanted 12B was undetected in the present experiment.

Izumikawa, T.; Mihara, M.; Matsuta, K.; Fukuda, M.; Ohtsubo, T.; Ohya, S.; Minamisono, T.

2015-02-01

247

Understanding NMR relaxometry of partially water-saturated rocks  

NASA Astrophysics Data System (ADS)

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

Mohnke, O.; Nordlund, C.; Jorand, R.; Klitzsch, N.

2014-11-01

248

Interactions between cations and peat organic matter monitored with NMR wideline, static and FFC NMR relaxometry  

NASA Astrophysics Data System (ADS)

The molecular size of humic substances is still under debate and is believed to range up to several hundred thousands Dalton, although a number of recent studies suggest much lower molecular weights. Nowadays an increasing number of authors suggest a model of molecular aggregates. One explanation why results on the molecular mass of humic materials are contradictory, may be that individual OM molecules are linked via intermolecular interactions, by bridges of water molecules or by cations bridging cation exchange sites (Schaumann, 2006a, b). Properties of such cross-linked systems can be similar to macromolecular systems revealing covalent cross-links. In this context, multivalent cations play an important ecological role, serving as reversible cross-linking agent. Formation and disruption of such cation bridges may close or open sorption sites in soil organic matter. Although cross-linking by multivalent cations has been proposed in many studies, the cross-linking effect has not yet been demonstrated on the molecular scale. The objective of this study was to investigate the interactions between cations and peat organic matter using NMR wideline techniques as well as static and fast field cycling (FFC) NMR relaxometry. Peat treated with solutions containing either Na+, Ca2+ or Al3+ was investigated in air-dried state for longitudinal relaxation times (T1) and NMR wideline characteristics. T1 distributions were separated into two Gaussian functions which were interpreted to represent two proton populations belonging to two environments of differing mobility. The relaxation rates (R1 = T1-1) in the cation treated samples spread over a range of 87-123 s-1 (R1a: fast component) and 32-42 s-1 (R1b: slow component). The rates in all treatments are significantly different from each other. and decrease in the order conditioned sample > desalinated sample > Na-treated sample. The treatment with multivalent cations affects R1a and R1b in different ways and needs more detailed explanation. Wideline proton NMR spectra can be used to quantify proton containing material, mainly water, based on their mobility. Spectra were decomposed into a Gaussian and Lorentzian line and changes to mobility after heat treatment indicate the water binding strength. In this study, differences in the various NMR parameters on the cation treatments will be presented and discussed with respect to the crosslinking hypothesis.

Schaumann, Gabriele E.; Conte, Pellegrino; Jäger, Alexander; Alonzo, Giuseppe; Bertmer, Marko

2010-05-01

249

Solution solution: using NMR models for molecular replacement  

Microsoft Academic Search

NMR structures can serve as a good source of search models in crystal\\u000a\\u0009structure determination by molecular replacement. However, owing\\u000a\\u0009to the inherent problems of NMR models, this procedure is not always\\u000a\\u0009straightforward. Here, an updated overview is presented with particular\\u000a\\u0009emphasis on the preparation of NMR search models and the latest trends\\u000a\\u0009in methodology. An experimental protocol developed recently

Yu Wai Chen

2001-01-01

250

Fragment-Based Drug Discovery Using NMR Spectroscopy  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy has evolved into a powerful tool for fragment-based drug discovery over the last two decades. While NMR has been traditionally used to elucidate the three-dimensional structures and dynamics of biomacromolecules and their interactions, it can also be a very valuable tool for the reliable identification of small molecules that bind to proteins and for hit-to-lead optimization. Here, we describe the use of NMR spectroscopy as a method for fragment-based drug discovery and how to most effectively utilize this approach for discovering novel therapeutics based on our experience. PMID:23686385

Harner, Mary J.; Frank, Andreas O.; Fesik, Stephen W.

2013-01-01

251

High-field NMR using resistive and hybrid magnets.  

PubMed

Resistive and resistive-superconducting hybrid magnets can generate dc magnetic fields much higher than conventional superconducting NMR magnets but the field spatial homogeneity and temporal stability are usually not sufficient for high-resolution NMR experiments. Hardware and technique development addressing these issues are presented for high-resolution NMR at magnetic fields up to 40T. Passive ferromagnetic shimming and magic-angle spinning are used effectively to reduce the broadening from inhomogeneous magnetic field. A phase correction technique based on simultaneous heteronuclear detection is developed to compensate magnetic field fluctuations to achieve high spectral resolution. PMID:18226940

Gan, Zhehong; Kwak, Hyung-Tae; Bird, Mark; Cross, Timothy; Gor'kov, Peter; Brey, William; Shetty, Kiran

2008-03-01

252

NMR contributions to structural dynamics studies of intrinsically disordered proteins?  

PubMed Central

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

Konrat, Robert

2014-01-01

253

Robustness of quantum discord to sudden death in NMR  

E-print Network

We investigate the dynamics of entanglement and quantum discord of two qubits in liquid state homonuclear NMR. Applying a phenomenological description for NMR under relaxation process, and taking a group of typical parameters of NMR, we show that when a zero initial state $|00> $ experiences a relaxation process, its entanglement disappears completely after a sequence of so-called sudden deaths and revivals, while the quantum discord retains remarkable values after a sequence of oscillations. That is to say, the quantum discord is more robust than entanglement.

Jianwei Xu; Qihui Chen

2011-06-01

254

Exposing the Moving Parts of Proteins with NMR Spectroscopy  

PubMed Central

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for investigating the dynamics of biomolecules since it provides a description of motion that is comprehensive, site-specific, and relatively non-invasive. In particular, the study of protein dynamics has benefited from sustained methodological advances in NMR that have expanded the scope and time scales of accessible motion. Yet, many of these advances may not be well known to the more general physical chemistry community. Accordingly, this Perspective provides a glimpse of some of the more powerful methods in liquid state NMR that are helping reshape our understanding of functional motions of proteins. PMID:22545175

Peng, J.W.

2012-01-01

255

NMR imaging of components and materials for DOE application  

SciTech Connect

The suitability for using NMR imaging to characterize liquid, polymeric, and solid materials was reviewed. The most attractive applications for NMR imaging appear to be liquid-filled porous samples, partially cured polymers, adhesives, and potting compounds, and composite polymers/high explosives containing components with widely varying thermal properties. Solid-state NMR line-narrowing and signal-enhancing markedly improve the imaging possibilities of true solid and materials. These techniques provide unique elemental and chemical shift information for highly complex materials and complement images with similar spatial resolution, such as X-ray computed tomography (CT).

Richardson, B.R.

1993-12-01

256

Simultaneous Phase and Scatter Correction for NMR Datasets  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy has proven invaluable in the diverse field of chemometrics due to its ability to deliver information-rich spectral datasets of complex mixtures for analysis by techniques such as principal component analysis (PCA). However, NMR datasets present a unique challenge during preprocessing due to differences in phase offsets between individual spectra, thus complicating the correction of random dilution factors that may also occur. We show that simultaneously correcting phase and dilution errors in NMR datasets representative of metabolomics data yields improved cluster quality in PCA scores space, even with significant initial phase errors in the data. PMID:24489421

Worley, Bradley; Powers, Robert

2014-01-01

257

Characterization of a chiral nematic mesoporous organosilica using NMR  

NASA Astrophysics Data System (ADS)

Using templation with nanocrystalline cellulose, a mesoporous organosilica film with a chiral nematic pore structure has recently been developed. [1] We have used a variety of Nuclear Magnetic Resonance (NMR) techniques to characterize the pore structure. The pore size distribution has been found by analyzing the freezing point depression of absorbed water via NMR cryoporometry. The effective longitudinal and transverse pore diameters for diffusing water were investigated with Pulsed-Field Gradient (PFG) NMR and compared to a 1-D connected-pore model. Preliminary data on testing imposed chiral ordering in absorbed liquid crystals is also presented. [4pt] [1] K.E. Shopsowitz et al. JACS 134(2), 867 (2012)

Manning, Alan; Shopsowitz, Kevin; Giese, Michael; MacLachlan, Mark; Dong, Ronald; Michal, Carl

2012-10-01

258

Capillary toroid cavity detector for high pressure NMR  

DOEpatents

A Toroid Cavity Detector (TCD) is provided for implementing nuclear magnetic resonance (NMR) studies of chemical reactions under conditions of high pressures and temperatures. A toroid cavity contains an elongated central conductor extending within the toroid cavity. The toroid cavity and central conductor generate an RF magnetic field for NMR analysis. A flow-through capillary sample container is located within the toroid cavity adjacent to the central conductor to subject a sample material flowing through the capillary to a static magnetic field and to enable NMR spectra to be recorded of the material in the capillary under a temperature and high pressure environment.

Gerald, II, Rex E. (Brookfield, IL); Chen, Michael J. (Downers Grove, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Honer Glen, IL); ter Horst, Marc (Chapel Hill, NC)

2007-09-11

259

NMR Methods, Applications and Trends for Groundwater Evaluation and Management  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) measurements have a tremendous potential for improving groundwater characterization, as they provide direct detection and measurement of groundwater and unique information about pore-scale properties. NMR measurements, commonly used in chemistry and medicine, are utilized in geophysical investigations through non-invasive surface NMR (SNMR) or downhole NMR logging measurements. Our recent and ongoing research has focused on improving the performance and interpretation of NMR field measurements for groundwater characterization. Engineering advancements have addressed several key technical challenges associated with SNMR measurements. Susceptibility of SNMR measurements to environmental noise has been dramatically reduced through the development of multi-channel acquisition hardware and noise-cancellation software. Multi-channel instrumentation (up to 12 channels) has also enabled more efficient 2D and 3D imaging. Previous limitations in measuring NMR signals from water in silt, clay and magnetic geology have been addressed by shortening the instrument dead-time from 40 ms to 4 ms, and increasing the power output. Improved pulse sequences have been developed to more accurately estimate NMR relaxation times and their distributions, which are sensitive to pore size distributions. Cumulatively, these advancements have vastly expanded the range of environments in which SNMR measurements can be obtained, enabling detection of groundwater in smaller pores, in magnetic geology, in the unsaturated zone, and nearby to infrastructure (presented here in case studies). NMR logging can provide high-resolution estimates of bound and mobile water content and pore size distributions. While NMR logging has been utilized in oil and gas applications for decades, its use in groundwater investigations has been limited by the large size and high cost of oilfield NMR logging tools and services. Recently, engineering efforts funded by the US Department of Energy have produced an NMR logging tool that is much smaller and less costly than comparable oilfield NMR logging tools. This system is specifically designed for near surface groundwater investigations, incorporates small diameter probes (as small as 1.67 inches diameter) and man-portable surface stations, and provides NMR data and information content on par with oilfield NMR logging tools. A direct-push variant of this logging tool has also been developed. Key challenges associated with small diameter tools include inherently lower SNR and logging speeds, the desire to extend the sensitive zone as far as possible into unconsolidated formations, and simultaneously maintaining high power and signal fidelity. Our ongoing research in groundwater NMR aims to integrating surface and borehole measurements for regional-scale permeability mapping, and to develop in-place NMR sensors for long term monitoring of contaminant and remediation processes. In addition to groundwater resource characterization, promising new applications of NMR include assessing water content in ice and permafrost, management of groundwater in mining operations, and evaluation and management of groundwater in civil engineering applications.

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

2011-12-01

260

Liquid State NMR Quantum Computing Lieven M. K. Vandersypen, Costantino S. Yannoni, and Isaac L. Chuang  

E-print Network

Liquid State NMR Quantum Computing Lieven M. K. Vandersypen, Costantino S. Yannoni, and Isaac L #12;LIQUID STATE NMR QUANTUM COMPUTING 1 Liquid State NMR Quantum Computing Lieven M. K. Vandersypen, Selft, The Netherlands 1 Introduction 1 2 Quantum Computation 1 3 NMR Quantum Computers 4 4 Summary

261

Jointly deriving NMR surface relaxivity and pore size distributions by NMR relaxation experiments on partially desaturated rocks  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) relaxometry is a geophysical method widely used in borehole and laboratory applications to nondestructively infer transport and storage properties of rocks and soils as it is directly sensitive to the water/oil content and pore sizes. However, for inferring pore sizes, NMR relaxometry data need to be calibrated with respect to a surface interaction parameter, surface relaxivity, which depends on the type and mineral constituents of the investigated rock. This study introduces an inexpensive and quick alternative to the classical calibration methods, e.g., mercury injection, pulsed field gradient (PFG) NMR, or grain size analysis, which allows for jointly estimating NMR surface relaxivity and pore size distributions using NMR relaxometry data from partially desaturated rocks. Hereby, NMR relaxation experiments are performed on the fully saturated sample and on a sample partially drained at a known differential pressure. Based on these data, the (capillary) pore radius distribution and surface relaxivity are derived by joint optimization of the Brownstein-Tarr and the Young-Laplace equation assuming parallel capillaries. Moreover, the resulting pore size distributions can be used to predict water retention curves. This inverse modeling approach—tested and validated using NMR relaxometry data measured on synthetic porous borosilicate samples with known petrophysical properties (i.e., permeability, porosity, inner surfaces, pore size distributions)—yields consistent and reproducible estimates of surface relaxivity and pore radii distributions. Also, subsequently calculated water retention curves generally correlate well with measured water retention curves.

Mohnke, O.; Hughes, B.

2014-06-01

262

A Covariance NMR Toolbox for MATLAB and OCTAVE  

PubMed Central

The Covariance NMR Toolbox is a new software suite that provides a streamlined implementation of covariance-based analysis of multi-dimensional NMR data. The Covariance NMR Toolbox uses the MATLAB or, alternatively, the freely available GNU OCTAVE computer language, providing a user-friendly environment in which to apply and explore covariance techniques. Covariance methods implemented in the toolbox described here include direct and indirect covariance processing, 4D covariance, generalized indirect covariance (GIC), and Z-matrix transform. In order to provide compatibility with a wide variety of spectrometer and spectral analysis platforms, the Covariance NMR Toolbox uses the NMRPipe format for both input and output files. Additionally, datasets small enough to fit in memory are stored as arrays that can be displayed and further manipulated in a versatile manner within MATLAB or OCTAVE. PMID:21215669

Short, Timothy; Alzapiedi, Leigh; Brüschweiler, Rafael; Snyder, David

2011-01-01

263

Diffusive MASS NMR Studies of Transport in Porous Materials  

E-print Network

NMR methods are widely used to probe the structure and fluid dynamics of porous materials including such diverse materials as cheese and chocolate, cosmetics and pharmaceuticals, solvents in resins and soft matter, biological ...

Sen, Pabitra

2001-01-01

264

A high-pressure NMR probe for aqueous geochemistry.  

PubMed

A non-magnetic piston-cylinder pressure cell is presented for solution-state NMR spectroscopy at geochemical pressures. The probe has been calibrated up to 20?kbar using in?situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10??L of sample in a microcoil. Initial (11)B?NMR spectroscopy of the H3BO3-catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation. The inexpensive probe design doubles the current pressure range available for solution NMR spectroscopy and is particularly important to advance the field of aqueous geochemistry. PMID:24989120

Pautler, Brent G; Colla, Christopher A; Johnson, Rene L; Klavins, Peter; Harley, Stephen J; Ohlin, C André; Sverjensky, Dimitri A; Walton, Jeffrey H; Casey, William H

2014-09-01

265

Study of molecular interactions with 13C DNP-NMR  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

266

Structural studies of amyloid fibrils using solid-state NMR  

E-print Network

he development of solid-state NMR techniques and application to amyloid fibrils are presented. In addition, a new method of selective inversion based on chemical shift anisotropy is presented. An improved method for highly ...

Caporini, Marc Anthony

2008-01-01

267

Protein MAS NMR methodology and structural analysis of protein assemblies  

E-print Network

Methodological developments and applications of solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, with particular emphasis on the analysis of protein structure, are described in this thesis. ...

Bayro, Marvin J

2010-01-01

268

Mixing and Matching Detergents for Membrane Protein NMR Structure Determination  

SciTech Connect

One major obstacle to membrane protein structure determination is the selection of a detergent micelle that mimics the native lipid bilayer. Currently, detergents are selected by exhaustive screening because the effects of protein-detergent interactions on protein structure are poorly understood. In this study, the structure and dynamics of an integral membrane protein in different detergents is investigated by nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy and small-angle X-ray scattering (SAXS). The results suggest that matching of the micelle dimensions to the protein's hydrophobic surface avoids exchange processes that reduce the completeness of the NMR observations. Based on these dimensions, several mixed micelles were designed that improved the completeness of NMR observations. These findings provide a basis for the rational design of mixed micelles that may advance membrane protein structure determination by NMR.

Columbus, Linda; Lipfert, Jan; Jambunathan, Kalyani; Fox, Daniel A.; Sim, Adelene Y.L.; Doniach, Sebastian; Lesley, Scott A.; (Stanford); (Scripps); (UV)

2009-10-21

269

Proton NMR Spectra: Deceptively Simple and Deceptively Complex Examples.  

ERIC Educational Resources Information Center

Describes relatively simple nuclear magnetic resonance (NMR) experiments that demonstrate unexpected results of the deceptively simple and deceptively complex types. Background information, experimental procedures, and typical results obtained are included. (JN)

Gurst, J. E.; And Others

1985-01-01

270

Investigation of Zeolite Nucleation and Growth Using NMR Spectroscopy  

E-print Network

and control of the zeolite properties. The primary objective of this dissertation is to determine the strength of organicinorganic interactions (i.e., the adsorption Gibbs energy) in transparent synthesis mixtures using PFG NMR spectroscopy, in order...

Rivas Cardona, Alejandra

2012-02-14

271

International NMR-based Environmental Metabolomics Intercomparison Exercise  

EPA Science Inventory

Several fundamental requirements must be met so that NMR-based metabolomics and the related technique of metabonomics can be formally adopted into environmental monitoring and chemical risk assessment. Here we report an intercomparison exercise which has evaluated the effectivene...

272

NMR methods for in-situ biofilm metabolism studies  

SciTech Connect

Novel procedures and instrumentation are described for nuclear magnetic resonance (NMR) spectroscopy and imaging studies of live, in situ microbial films. A perfused NMR/optical microscope sample chamber containing a planar biofilm support was integrated into a recirculation/dilution flow loop growth reactor system and used to grow in situ Shewanella oneidensis strain MR-1 biofilms. Localized NMR techniques were developed and used to non-invasively monitor time-resolved metabolite concentrations and to image the biomass volume and distribution. As a first illustration of the feasibility of the methodology an initial 13C-labeled lactate metabolic pathway study was performed, yielding results consistent with existing genomic data for MR-1. These results represent progress toward our ultimate goal of correlating time- and depth-resolved metabolism and mass transport with gene expression in live in situ biofilms using combined NMR/optical microscopy techniques.

Majors, Paul D.; Mclean, Jeffrey S.; Pinchuk, Gregory E.; Fredrickson, Jim K.; Gorby, Yuri A.; Minard, Kevin R.; Wind, Robert A.

2005-09-01

273

Surface Enhanced NMR Spectroscopy by Dynamic Nuclear Polarization Anne Lesage,  

E-print Network

the possibility to directly investigate both the bulk (silica and/or alumina) and surface functionalities (e to a 50-fold increase in the NMR sensitivity of molecular organic functionalities of hybrid silica

274

Dynamic nuclear polarization for NMR : applications and hardware development  

E-print Network

solid State NMR (SSNMR) can determine molecular as well as supermolecular structure and dynamics. The low signal intensities make many of these experiments prohibitively long. Dynamic Nuclear Polarization provides a method ...

Casey, Andrew (Andrew Byron)

2008-01-01

275

Use of NMR techniques for toxic organophosphorus compound profiling.  

PubMed

This review presents with selected examples the versatility of nuclear magnetic resonance (NMR) spectroscopy in the analysis of toxic organophosphorus (OP) compounds, i.e. OP pesticides and chemical warfare agents (CWAs). Several NMR applications of biological importance, like studies on inhibition mechanism, metabolism, and exposure determination, are presented. The review also concerns with the environmental analysis of OP compounds by NMR spectroscopy. Residue analysis of environment and food samples as well as characterization of degradation in environment is discussed. Some of the NMR studies that have been done to support the Chemical Weapons Convention, i.e. the development of suitable CWA detoxification means and the method development of verification analysis for CWAs and their degradation products, are outlined. PMID:19939751

Koskela, Harri

2010-05-15

276

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

PubMed

Seeing the big picture: Asymmetric macromolecular complexes that are NMR active in only a subset of their subunits can be prepared, thus decreasing NMR spectral complexity. For the hetero heptameric LSm1-7 and LSm2-8 rings NMR spectra of the individual subunits of the complete complex are obtained, showing a conserved RNA binding site. This LEGO-NMR technique makes large asymmetric complexes accessible to detailed NMR spectroscopic studies. PMID:23946163

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

2013-10-18

277

Calculation of Symmetric Oligomer Structures from NMR Data  

Microsoft Academic Search

The size range of proteins amenable to NMR spectroscopy has extended to the point where protein oligomer structures are now\\u000a being routinely determined. Many are symmetric; we found 36 symmetric oligomers solved by NMR in the present protein structure\\u000a database: 32 dimers, 2 tetramers, 1 pentamer, and 1 hexamer. Hence, we anticipate that an increasing number of symmetric oligomer\\u000a structures

Seán I. O’Donoghue; Michael Nilges

278

Structure-based protein NMR assignments using native structural ensembles  

Microsoft Academic Search

An important step in NMR protein structure determination is the assignment of resonances and NOEs to corresponding nuclei.\\u000a Structure-based assignment (SBA) uses a model structure (“template”) for the target protein to expedite this process. Nuclear\\u000a vector replacement (NVR) is an SBA framework that combines multiple sources of NMR data (chemical shifts, RDCs, sparse NOEs,\\u000a amide exchange rates, TOCSY) and has

Mehmet Serkan Apayd?n; Vincent Conitzer; Bruce Randall Donald

2008-01-01

279

NMR of molecules interacting with lipids in small unilamellar vesicles  

Microsoft Academic Search

Detailed characterization of protein, peptide or drug interactions with natural membrane is still a challenge. This review\\u000a focuses on the use of nuclear magnetic resonance (NMR) for the analysis of interaction of molecules with small unilamellar\\u000a vesicles (SUV). These phospholipid vesicles are often used as model membranes for fluorescence or circular dichroism experiments.\\u000a The various NMR approaches for studying molecule-lipid

Grégory Da Costa; Liza Mouret; Soizic Chevance; Elisabeth Le Rumeur; Arnaud Bondon

2007-01-01

280

Pulsed NMR analysis of ion-selective electrode membranes.  

PubMed

A novel method for evaluation of ion-selective electrode membranes was reported with the proton spin-spin relaxation time T(2) by pulsed NMR. The proton spin-spin relaxation time T(2) measurements provided valuable information about properties of the whole membrane matrix. The softer potentiometric liquid membrane possessed a large fraction F(L) providing relatively longer T(2) value. Pulsed NMR method can quantify the degree of the plasticization of ion-selective electrode membranes. PMID:21210048

Moriuchi-Kawakami, Takayo; Kizuki, Maremi; Takeuchi, Hidekazu; Shibutani, Yasuhiko

2011-03-01

281

High Pressure Nmr Studies of Chemical and Biochemical Systems  

Microsoft Academic Search

\\u000a Nuclear magnetic measurements at high pressure provide unique information about the microscopic behavior of chemical and biochemical\\u000a systems. In view of the high information content of advanced high resolution NMR techniques including 2D and 3D NMR, the ability\\u000a of performing these experiments at high pressure opens a very promising direction in high pressure research.\\u000a \\u000a \\u000a This review is organized in the

Jiri Jonas

282

Fluid-Rock Characterization and Interactions in NMR Well Logging  

SciTech Connect

The objective of this project was to characterize the fluid properties and fluid-rock interactions which are needed for formation evaluation by NMR well logging. NMR well logging is finding wide use in formation evaluation. The formation parameters commonly estimated were porosity, permeability, and capillary bound water. Special cases include estimation of oil viscosity, residual oil saturation, location of oil/water contact, and interpretation on whether the hydrocarbon is oil or gas.

Hirasaki, George J.; Mohanty, Kishore K.

2003-02-10

283

Quantitative NMR Analysis of Partially Substituted Biodiesel Glycerols  

SciTech Connect

Phosphitylation of hydroxyl groups in biodiesel samples with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane followed by 31P-NMR analysis provides a rapid quantitative analytical technique for the determination of substitution patterns on partially esterified glycerols. The unique 31P-NMR chemical shift data was established with a series mono and di-substituted fatty acid esters of glycerol and then utilized to characterize an industrial sample of partially processed biodiesel.

Nagy, M.; Alleman, T. L.; Dyer, T.; Ragauskas, A. J.

2009-01-01

284

A Quick and Easy Simplification of Benzocaine's NMR Spectrum  

NASA Astrophysics Data System (ADS)

The preparation of benzocaine is a common experiment used in sophomore-level organic chemistry. Its straightforward procedure and predictable good yields make it ideal for the beginning organic student. Analysis of the product via NMR spectroscopy, however, can be confusing to the novice interpreter. An inexpensive, quick, and effective method for simplifying the NMR spectrum is reported. The method results in a spectrum that is cleanly integrated and more easily interpreted.

Carpenter, Suzanne R.; Wallace, Richard H.

2006-04-01

285

The study of methane adsorbed on porous silicon by NMR  

E-print Network

THE STUDY OF METHANE ADSORBED ON POROUS SILICON BY NMR A Thesis by ADAM KAZIMIERZ CZERMAK Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1986... Major Subject: Physics THE STUDY OF METHANE ADSORBED ON POROUS SILICON BY NMR A Thesis by ADAM KAZIMIERZ CZERMAK Approved as to style and content by: e Wile . Kirk (Chairman of Committee) J eevak M. Par pi a (Member) Randall L. Geiger...

Czermak, Adam Kazimierz

1986-01-01

286

Investigation of porous media structures using NMR restricted diffusion measurements  

E-print Network

INVESTIGATION OF POROUS MEDIA STRUCTURES USING NMR RESTRICTED DIFFUSION MEASUREMENTS A Thesis by PEIZHI MIAO Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 1993 Major Subject: Chemical Engineering INVESTIGATION OF POROUS MEDIA STRUCTURES USING NMR RESTRICTED DIFFUSION MEASUREMENTS A Thesis by PEIZHI MIAO Approved ss to style and content by: A. T. Watson (Chair of Committee) C...

Miao, Peizhi

1993-01-01

287

Flow units from integrated WFT and NMR data  

SciTech Connect

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

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

1997-08-01

288

Deuterium incorporation in biomass cell wall components by NMR analysis  

SciTech Connect

A commercially available deuterated kale sample was analyzed for deuterium incorporation by ionic liquid solution 2H and 1H nuclear magnetic resonance (NMR). This protocol was found to effectively measure the percent deuterium incorporation at 33%, comparable to the 31% value determined by combustion. The solution NMR technique also suggested by a qualitative analysis that deuterium is preferentially incorporated into the carbohydrate components of the kale sample.

Foston, Marcus B [ORNL; McGaughey, Joseph [ORNL; O'Neill, Hugh Michael [ORNL; Evans, Barbara R [ORNL; Ragauskas, Arthur J [ORNL

2012-01-01

289

Structural Biology by NMR: Structure, Dynamics, and Interactions  

Microsoft Academic Search

The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to

Phineus R. L. Markwick; Thérèse Malliavin; Michael Nilges

2008-01-01

290

NMR studies of DNA microcapsules prepared using sonochemical methods.  

PubMed

DNA molecules were recently converted using ultrasonic irradiation into microcapsules that can trap hydrophobic molecules in aqueous solution. These DNA microcapsules are capable of penetrating prokaryotic and eukaryotic cells, delivering drugs and transferring genetic information e.g. for protein expression into the host cells. DNA molecules of different sizes and structures can be assembled into spherical capsules, but to date, the interactions that hold them together in these large structural constructs are unknown. In the current study, capsules prepared from a 12 base double helix DNA were investigated using NMR spectroscopy. Solution NMR studies of the DNA emulsion reveal DNA molecules with a perturbed structure with a size similar to the precursor DNA based on diffusion NMR measurements. 2D NMR correlation measurements and chemical shift perturbation analysis show partial unzipping of AT base pairs in the centre of the modified duplex, freeing nucleoside bases to interact with other bases on other precursor molecules thereby facilitating aggregation. Slow tumbling of the microspheres renders them invisible in solution NMR spectra; therefore magic angle spinning NMR measurements are performed which provide limited evidence of the DNA in the microcapsule state. PMID:25470741

Reytblat, Irena; Keinan-Adamsky, Keren; Chill, Jordan H; Gottlieb, Hugo E; Gedanken, Aharon; Goobes, Gil

2015-01-21

291

Nanoscale NMR spectroscopy and imaging of multiple nuclear species  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple nuclear species in bulk matter, with wide-ranging applications from basic physics and chemistry to biomedical imaging. However, the spatial resolution of conventional NMR and MRI is limited to several micrometres even at large magnetic fields (>1?T), which is inadequate for many frontier scientific applications such as single-molecule NMR spectroscopy and in vivo MRI of individual biological cells. A promising approach for nanoscale NMR and MRI exploits optical measurements of nitrogen–vacancy (NV) colour centres in diamond, which provide a combination of magnetic field sensitivity and nanoscale spatial resolution unmatched by any existing technology, while operating under ambient conditions in a robust, solid-state system. Recently, single, shallow NV centres were used to demonstrate NMR of nanoscale ensembles of proton spins, consisting of a statistical polarization equivalent to ?100–1,000 spins in uniform samples covering the surface of a bulk diamond chip. Here, we realize nanoscale NMR spectroscopy and MRI of multiple nuclear species (1H, 19F, 31P) in non-uniform (spatially structured) samples under ambient conditions and at moderate magnetic fields (?20?mT) using two complementary sensor modalities.

Devience, Stephen J.; Pham, Linh M.; Lovchinsky, Igor; Sushkov, Alexander O.; Bar-Gill, Nir; Belthangady, Chinmay; Casola, Francesco; Corbett, Madeleine; Zhang, Huiliang; Lukin, Mikhail; Park, Hongkun; Yacoby, Amir; Walsworth, Ronald L.

2015-02-01

292

Protein folding on the ribosome studied using NMR spectroscopy  

PubMed Central

NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome–nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity. PMID:24083462

Waudby, Christopher A.; Launay, Hélène; Cabrita, Lisa D.; Christodoulou, John

2013-01-01

293

Conjoined Use of EM and NMR in RNA Structure Refinement  

PubMed Central

More than 40% of the RNA structures have been determined using nuclear magnetic resonance (NMR) technique. NMR mainly provides local structural information of protons and works most effectively on relatively small biomacromolecules. Hence structural characterization of large RNAs can be difficult for NMR alone. Electron microscopy (EM) provides global shape information of macromolecules at nanometer resolution, which should be complementary to NMR for RNA structure determination. Here we developed a new energy term in Xplor-NIH against the density map obtained by EM. We conjointly used NMR and map restraints for the structure refinement of three RNA systems — U2/U6 small-nuclear RNA, genome-packing motif (?CD)2 from Moloney murine leukemia virus, and ribosome-binding element from turnip crinkle virus. In all three systems, we showed that the incorporation of a map restraint, either experimental or generated from known PDB structure, greatly improves structural precision and accuracy. Importantly, our method does not rely on an initial model assembled from RNA duplexes, and allows full torsional freedom for each nucleotide in the torsion angle simulated annealing refinement. As increasing number of macromolecules can be characterized by both NMR and EM, the marriage between the two techniques would enable better characterization of RNA three-dimensional structures. PMID:25798848

Gong, Zhou; Schwieters, Charles D.; Tang, Chun

2015-01-01

294

NMR-spectroscopic analysis of mixtures: from structure to function  

PubMed Central

NMR spectroscopy as a particularly information-rich method offers unique opportunities for improving the structural and functional characterization of metabolomes, which will be essential for advancing the understanding of many biological processes. Whereas traditionally NMR spectroscopy was mostly relegated to the characterization of pure compounds, the last few years have seen a surge of interest in using NMR spectroscopic techniques for characterizing complex metabolite mixtures. Development of new methods was motivated partly by the realization that using NMR for the analysis of metabolite mixtures can help identify otherwise inaccessible small molecules, for example compounds that are prone to chemical decomposition and thus cannot be isolated. Furthermore, comparative metabolomics and statistical analyses of NMR-spectra have proven highly effective at identifying novel and known metabolites that correlate with changes in genotype or phenotype. In this review, we provide an overview of the range of NMR spectroscopic techniques recently developed for characterizing metabolite mixtures, including methods used in discovery-oriented natural product chemistry, in the study of metabolite biosynthesis and function, or for comparative analyses of entire metabolomes. PMID:21071261

Forseth, Ry R.; Schroeder, Frank C.

2010-01-01

295

Nanoscale NMR Spectroscopy and Imaging of Multiple Nuclear Species  

E-print Network

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are well-established techniques that provide valuable information in a diverse set of disciplines but are currently limited to macroscopic sample volumes. Here we demonstrate nanoscale NMR spectroscopy and imaging under ambient conditions of samples containing multiple nuclear species, using nitrogen-vacancy (NV) colour centres in diamond as sensors. With single, shallow NV centres in a diamond chip and samples placed on the diamond surface, we perform NMR spectroscopy and one-dimensional MRI on few-nanometre-sized samples containing $^1$H and $^{19}$F nuclei. Alternatively, we employ a high-density NV layer near the surface of a diamond chip to demonstrate wide-field optical NMR spectroscopy of nanoscale samples containing $^1$H, $^{19}$F, and $^{31}$P nuclei, as well as multi-species two-dimensional optical MRI with sub-micron resolution. For all diamond samples exposed to air, we identify a ubiquitous $^1$H NMR signal, consistent with a $\\sim 1$ nm layer of adsorbed hydrocarbons or water on the diamond surface and below any sample placed on the diamond. This work lays the foundation for nanoscale NMR and MRI applications such as studies of single proteins and functional biological imaging with subcellular resolution, as well as characterization of thin films with sub-nanometre resolution.

Stephen J. DeVience; Linh M. Pham; Igor Lovchinsky; Alexander O. Sushkov; Nir Bar-Gill; Chinmay Belthangady; Francesco Casola; Madeleine Corbett; Huiliang Zhang; Mikhail Lukin; Hongkun Park; Amir Yacoby; Ronald L. Walsworth

2014-06-12

296

Nanoscale NMR spectroscopy and imaging of multiple nuclear species.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple nuclear species in bulk matter, with wide-ranging applications from basic physics and chemistry to biomedical imaging. However, the spatial resolution of conventional NMR and MRI is limited to several micrometres even at large magnetic fields (>1?T), which is inadequate for many frontier scientific applications such as single-molecule NMR spectroscopy and in vivo MRI of individual biological cells. A promising approach for nanoscale NMR and MRI exploits optical measurements of nitrogen-vacancy (NV) colour centres in diamond, which provide a combination of magnetic field sensitivity and nanoscale spatial resolution unmatched by any existing technology, while operating under ambient conditions in a robust, solid-state system. Recently, single, shallow NV centres were used to demonstrate NMR of nanoscale ensembles of proton spins, consisting of a statistical polarization equivalent to ?100-1,000 spins in uniform samples covering the surface of a bulk diamond chip. Here, we realize nanoscale NMR spectroscopy and MRI of multiple nuclear species ((1)H, (19)F, (31)P) in non-uniform (spatially structured) samples under ambient conditions and at moderate magnetic fields (?20?mT) using two complementary sensor modalities. PMID:25559712

DeVience, Stephen J; Pham, Linh M; Lovchinsky, Igor; Sushkov, Alexander O; Bar-Gill, Nir; Belthangady, Chinmay; Casola, Francesco; Corbett, Madeleine; Zhang, Huiliang; Lukin, Mikhail; Park, Hongkun; Yacoby, Amir; Walsworth, Ronald L

2015-02-01

297

Solid-state NMR study of halogen-bonded adducts.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy offers unique insights into halogen bonds. NMR parameters such as chemical shifts, quadrupolar coupling constants, J coupling constants, and dipolar coupling constants are in principle sensitive to the formation and local structure of a halogen bond. Carrying out NMR experiments on halogen-bonded adducts in the solid state may provide several advantages over solution studies including (1) the absence of solvent which can interact with halogen bond donor sites and complicate spectral interpretation, (2) the lack of a need for single crystals or even long-range crystalline order, and (3) the potential to measure complete NMR interaction tensors rather than simply their isotropic values. In this chapter, we provide an overview of the NMR interactions and experiments which are relevant to the study of nuclei which are often found in halogen bonds (RX···Y) including (13)C, (35/37)Cl, (79/81)Br, (127)I, (77)Se, and (14/15)N. Experimental examples based on iodoperfluorobenzene halides, bis(trimethylammonium)alkane diiodide, and selenocyanate complexes, as well as haloanilinium halides, are discussed. Of particular interest is the sensitivity of the isotropic chemical shifts, the chemical shift tensor spans, and the halide nuclear electric quadrupolar coupling tensors to the halogen bond geometry in such compounds. Technical limitations associated with the NMR spectroscopy of covalently-bonded halogens are underlined. PMID:24760615

Bryce, David L; Viger-Gravel, Jasmine

2015-01-01

298

Conjoined use of em and NMR in RNA structure refinement.  

PubMed

More than 40% of the RNA structures have been determined using nuclear magnetic resonance (NMR) technique. NMR mainly provides local structural information of protons and works most effectively on relatively small biomacromolecules. Hence structural characterization of large RNAs can be difficult for NMR alone. Electron microscopy (EM) provides global shape information of macromolecules at nanometer resolution, which should be complementary to NMR for RNA structure determination. Here we developed a new energy term in Xplor-NIH against the density map obtained by EM. We conjointly used NMR and map restraints for the structure refinement of three RNA systems - U2/U6 small-nuclear RNA, genome-packing motif (?CD)2 from Moloney murine leukemia virus, and ribosome-binding element from turnip crinkle virus. In all three systems, we showed that the incorporation of a map restraint, either experimental or generated from known PDB structure, greatly improves structural precision and accuracy. Importantly, our method does not rely on an initial model assembled from RNA duplexes, and allows full torsional freedom for each nucleotide in the torsion angle simulated annealing refinement. As increasing number of macromolecules can be characterized by both NMR and EM, the marriage between the two techniques would enable better characterization of RNA three-dimensional structures. PMID:25798848

Gong, Zhou; Schwieters, Charles D; Tang, Chun

2015-01-01

299

SENSASS NMR: New NMR techniques for enhancing the sensitivity and the spectral resolution of polymer supported chemicals  

NASA Astrophysics Data System (ADS)

The use of polyethylene glycols (PEGs) as organic polymer soluble supports for synthesis has been receiving growing interest. The main advantages of using PEGs as support are related to their non-toxicity, their commercial availability and their solubility properties allowing easy recovery and analysis of compounds linked to the polymer. The NMR characterization of PEG-branched products could however be difficult due to the presence of huge signals of the polymeric support. In order to overcome this problem, we developed new NMR experiments named SENSitivity increAsed and resolution enhanced by Signal Suppression or SENSASS NMR. These experiments implement either semi-selective pulses or Water Gate sequences for reducing signals of the polymer as well as fast pulsing techniques optimizing the recycling delay for enhancing the sensitivity of signals. They have been successfully implemented in classical NMR characterization experiments namely, COSY, HSQC and HMBC experiments.

Prosa, Nicolò; Scherrmann, Marie-Christine; Merlet, Denis; Farjon, Jonathan

2013-12-01

300

SENSASS NMR: New NMR techniques for enhancing the sensitivity and the spectral resolution of polymer supported chemicals.  

PubMed

The use of polyethylene glycols (PEGs) as organic polymer soluble supports for synthesis has been receiving growing interest. The main advantages of using PEGs as support are related to their non-toxicity, their commercial availability and their solubility properties allowing easy recovery and analysis of compounds linked to the polymer. The NMR characterization of PEG-branched products could however be difficult due to the presence of huge signals of the polymeric support. In order to overcome this problem, we developed new NMR experiments named SENSitivity increAsed and resolution enhanced by Signal Suppression or SENSASS NMR. These experiments implement either semi-selective pulses or Water Gate sequences for reducing signals of the polymer as well as fast pulsing techniques optimizing the recycling delay for enhancing the sensitivity of signals. They have been successfully implemented in classical NMR characterization experiments namely, COSY, HSQC and HMBC experiments. PMID:24140624

Prosa, Nicolò; Scherrmann, Marie-Christine; Merlet, Denis; Farjon, Jonathan

2013-12-01

301

Para-hydrogen perspectives in hyperpolarized NMR.  

PubMed

The first instance of para-hydrogen induced polarization (PHIP) in an NMR experiment was serendipitously observed in the 1980s while investigating a hydrogenation reaction (Seldler et al., 1983; Bowers and Weitekamp, 1986, 1987; Eisenschmid et al., 1987) [1-4]. Remarkably a theoretical investigation of the applicability of para-hydrogen as a hyperpolarization agent was being performed in the 1980's thereby quickly providing a theoretical basis for the PHIP-effect (Bowers and Weitekamp, 1986) [2]. The discovery of signal amplification by a non-hydrogenating interaction with para-hydrogen has recently extended the interest to exploit the PHIP effect, as it enables investigation of compounds without structural alteration while retaining the advantages of spectroscopy with hyperpolarized compounds [5]. In this article we will place more emphasis of the future applications of the method while only briefly discussing the efforts that have been made in the understanding of the phenomenon and the development of the method so far. PMID:23932399

Glöggler, Stefan; Colell, Johannes; Appelt, Stephan

2013-10-01

302

Using metamaterial yokes in NMR measurements  

NASA Astrophysics Data System (ADS)

Swiss rolls are one instance of metamaterials, and can be described as an effective medium with a complex, anisotropic magnetic permeability. It has been shown that bundles of Swiss rolls can guide the magnetic flux in magnetic resonance measurements and increase the coupling between the nuclear spins and the receiver coil. Here, we investigate, with a numerical model, whether Swiss rolls can boost the detected signal in a NMR experiment, where the rolls could provide a low-reluctance return path for the magnetic flux when shaped in a yoke encircling the sample. The system consisting of the nuclear spin, the rolls and the receiver coil is analyzed with the method of finite differences in time domain (FDTD). The results show that small gains in the received signal are possible, but only if the losses (resistive and dielectric) in the rolls are reduced by over one order of magnitude from their present value in state-of-the-art materials. This situation arises because of the energy dissipation in the rolls and the mode splitting caused by the coupling between the rolls and the resonant coil.

Allard, Mathieu; Henkelman, R. Mark

2006-10-01

303

Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as (31)P qNMR standards.  

PubMed

Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that (1)H qNMR can be performed with high accuracy leading to measurement uncertainties below 1 % relative. It was even demonstrated that the combination of (1)H qNMR with metrological weighing can lead to measurement uncertainties below 0.1 % when highly pure substances are used. Although qNMR reference standards are already available as certified reference materials (CRM) providing traceability on the basis of (1)H qNMR experiments, there is an increasing demand for purity assays on phosphorylated organic compounds and metabolites requiring CRM for quantification by (31)P qNMR. Unfortunately, the number of available primary phosphorus standards is limited to a few inorganic CRM which only can be used for the analysis of water-soluble analytes but fail when organic solvents must be employed. This paper presents the concept of value assignment by (31)P qNMR measurements for the development of CRM and describes different approaches to establish traceability to primary Standard Reference Material from the National Institute of Standards and Technology (NIST SRM). Phosphonoacetic acid is analyzed as a water-soluble CRM candidate, whereas triphenyl phosphate is a good candidate for the use as qNMR reference material in organic solvents. These substances contain both nuclei, (1)H and (31)P, and the concept is to show that it is possible to indirectly quantify a potential phosphorus standard via its protons using (1)H qNMR. The same standard with its assigned purity can then be used for the quantification of an analyte via its phosphorus using (31)P qNMR. For the validation of the concept, triphenyl phosphate and phosphonoacetic acid have been used as (31)P qNMR standards to determine the purity of the analyte tris(2-chloroethyl) phosphate, and the resulting purity values perfectly overlap within their expanded measurement uncertainties. PMID:25416230

Weber, Michael; Hellriegel, Christine; Rueck, Alexander; Wuethrich, Juerg; Jenks, Peter; Obkircher, Markus

2014-11-22

304

Operation of a 500 MHz high temperature superconducting NMR: towards an NMR spectrometer operating beyond 1 GHz.  

PubMed

We have begun a project to develop an NMR spectrometer that operates at frequencies beyond 1 GHz (magnetic field strength in excess of 23.5 T) using a high temperature superconductor (HTS) innermost coil. As the first step, we developed a 500 MHz NMR with a Bi-2223 HTS innermost coil, which was operated in external current mode. The temporal magnetic field change of the NMR magnet after the coil charge was dominated by (i) the field fluctuation due to a DC power supply and (ii) relaxation in the screening current in the HTS tape conductor; effect (i) was stabilized by the 2H field-frequency lock system, while effect (ii) decreased with time due to relaxation of the screening current induced in the HTS coil and reached 10(-8)(0.01 ppm)/h on the 20th day after the coil charge, which was as small as the persistent current mode of the NMR magnet. The 1D (1)H NMR spectra obtained by the 500 MHz LTS/HTS magnet were nearly equivalent to those obtained by the LTS NMR magnet. The 2D-NOESY, 3D-HNCO and 3D-HNCACB spectra were achieved for ubiquitin by the 500 MHz LTS/HTS magnet; their quality was closely equivalent to that achieved by a conventional LTS NMR. Based on the results of numerical simulation, the effects of screening current-induced magnetic field changes are predicted to be harmless for the 1.03 GHz NMR magnet system. PMID:20149698

Yanagisawa, Y; Nakagome, H; Tennmei, K; Hamada, M; Yoshikawa, M; Otsuka, A; Hosono, M; Kiyoshi, T; Takahashi, M; Yamazaki, T; Maeda, H

2010-04-01

305

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

306

Noninvasive testing of art and cultural heritage by mobile NMR.  

PubMed

Nuclear magnetic resonance (NMR) has many applications in science, medicine, and technology. Conventional instrumentation is large and expensive, however, because superconducting magnets offer maximum sensitivity. Yet NMR devices can also be small and inexpensive if permanent magnets are used, and samples need not be placed within the magnet but can be examined externally in the stray magnetic field. Mobile stray-field NMR is a method of growing interest for nondestructive testing of a diverse range of materials and processes. A well-known stray-field sensor is the commercially available NMR-MOUSE, which is small and can readily be carried to an object to be studied. In this Account, we describe mobile stray-field NMR, with particular attention to its use in analyzing objects of cultural heritage. The most common data recorded are relaxation measurements of (1)H because the proton is the most sensitive NMR nucleus, and relaxation can be measured despite the inhomogeneous magnetic field that typically accompanies a simple magnet design. Through NMR relaxation, the state of matter can be analyzed locally, and the signal amplitude gives the proton density. A variety of stray-field sensors have been designed. Small devices weighing less than a kilogram have a shallow penetration depth of just a few millimeters and a resolution of a few micrometers. Access to greater depths requires larger sensors that may weigh 30 kg or more. The use of these sensors is illustrated by selected examples, including examinations of (i) the stratigraphy of master paintings, (ii) binder aging, (iii) the deterioration of paper, (iv) wood density in master violins, (v) the moisture content and moisture profiles in walls covered with paintings and mosaics, and (vi) the evolution of stone conservation treatments. The NMR data provide unique information to the conservator on the state of the object--including past conservation measures. The use of mobile NMR remains relatively new, expanding from field testing of materials such as roads, bridge decks, soil, and the contents of drilled wells to these more recent studies of objects of cultural heritage. As a young field, noninvasive testing of artworks with stray-field NMR thus offers many opportunities for research innovation and further development. PMID:20345119

Blümich, Bernhard; Casanova, Federico; Perlo, Juan; Presciutti, Federica; Anselmi, Chiara; Doherty, Brenda

2010-06-15

307

Solid-state NMR characterization of Mowry Formation shales  

SciTech Connect

Solid-state {sup 13}C and {sup 29}Si NMR measurements were carried out on a series of petroleum source rocks from the Mowry Formation of the Powder River Basin in Wyoming. The objectives of this study wereto use CP/MAS {sup 13}C NMR measurements to monitor changes in the carbon structure of the kerogen that result from depth of burial, and to examine the feasibility of {sup 29}Si NMR for studying the thermal alteration of clay minerals during diagenesis. Carbon and silicon NMR measurements were made on a suite of samples covering a present-day depth interval of 3,000 to 11,500 ft.In general, the NMR results endorsed other geochemical analyses that were performed on the source rocks as part of another study to examine pressure compartmentalization in the Mowry Formation. The carbon aromaticity of the kerogen increased with depth of burial, and at depths greater that approximately 10,000 ft the kerogen showed little capacity to generate additional oil because of the small fraction of residual aliphatic carbon. By combining NMR and Rock-Eval measurements, an estimate of the hydrogen budget was obtained. The calculations indicated that approximately 20% of the kerogen was converted to hydrocarbons, and that sufficient hydrogen was liberated from aromatization and condensation reactions to stabilize the generated products. The {sup 29}Si NMR spectra were characterized by a relatively sharp quartz resonance and a broad resonance from the clay minerals. With increasing depth of burial, the clay resonance became broader and shifted slightly downfield. These changes qualitatively support X-ray analysis that shows progressive alteration of illite to smectite with depth of burial.

Miknis, F.P.

1992-04-01

308

Solid-state NMR characterization of Mowry Formation shales  

SciTech Connect

Solid-state [sup 13]C and [sup 29]Si NMR measurements were carried out on a series of petroleum source rocks from the Mowry Formation of the Powder River Basin in Wyoming. The objectives of this study wereto use CP/MAS [sup 13]C NMR measurements to monitor changes in the carbon structure of the kerogen that result from depth of burial, and to examine the feasibility of [sup 29]Si NMR for studying the thermal alteration of clay minerals during diagenesis. Carbon and silicon NMR measurements were made on a suite of samples covering a present-day depth interval of 3,000 to 11,500 ft.In general, the NMR results endorsed other geochemical analyses that were performed on the source rocks as part of another study to examine pressure compartmentalization in the Mowry Formation. The carbon aromaticity of the kerogen increased with depth of burial, and at depths greater that approximately 10,000 ft the kerogen showed little capacity to generate additional oil because of the small fraction of residual aliphatic carbon. By combining NMR and Rock-Eval measurements, an estimate of the hydrogen budget was obtained. The calculations indicated that approximately 20% of the kerogen was converted to hydrocarbons, and that sufficient hydrogen was liberated from aromatization and condensation reactions to stabilize the generated products. The [sup 29]Si NMR spectra were characterized by a relatively sharp quartz resonance and a broad resonance from the clay minerals. With increasing depth of burial, the clay resonance became broader and shifted slightly downfield. These changes qualitatively support X-ray analysis that shows progressive alteration of illite to smectite with depth of burial.

Miknis, F.P.

1992-04-01

309

Hsp90 structure and function studied by NMR spectroscopy.  

PubMed

The molecular chaperone Hsp90 plays a crucial role in folding and maturation of regulatory proteins. Key aspects of Hsp90's molecular mechanism and its adenosine-5'-triphosphate (ATP)-controlled active cycle remain elusive. In particular the role of conformational changes during the ATPase cycle and the molecular basis of the interactions with substrate proteins are poorly understood. The dynamic nature of the Hsp90 machine designates nuclear magnetic resonance (NMR) spectroscopy as an attractive method to unravel both the chaperoning mechanism and interaction with partner proteins. NMR is particularly suitable to provide a dynamic picture of protein-protein interactions at atomic resolution. Hsp90 is rather a challenging protein for NMR studies, due to its high molecular weight and its structural flexibility. The recent technologic advances allowed overcoming many of the traditional obstacles. Here, we describe the different approaches that allowed the investigation of Hsp90 using state-of-the-art NMR methods and the results that were obtained. NMR spectroscopy contributed to understanding Hsp90's interaction with the co-chaperones p23, Aha1 and Cdc37. A particular exciting prospect of NMR, however, is the analysis of Hsp90 interaction with substrate proteins. Here, the ability of this method to contribute to the structural characterization of not fully folded proteins becomes crucial. Especially the interaction of Hsp90 with one of its natural clients, the tumour suppressor p53, has been intensively studied by NMR spectroscopy. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90). PMID:22155720

Didenko, Tatiana; Duarte, Afonso M S; Karagöz, G Elif; Rüdiger, Stefan G D

2012-03-01

310

Low Cost CE-NMR with Microcoils for Chemical Detection  

SciTech Connect

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

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

2008-07-25

311

Web Server Suite for Complex Mixture Analysis by Covariance NMR  

PubMed Central

Elucidation of the chemical composition of biological samples is a main focus of systems biology and metabolomics. Their comprehensive study requires reliable, efficient, and automatable methods to identify and quantify the underlying metabolites. Because nuclear magnetic resonance (NMR) spectroscopy is a rich source of molecular information, it has a unique potential for this task. Here we present a suite of public web servers (http://spinportal.magnet.fsu.edu), termed COLMAR, that facilitates complex mixture analysis by NMR. The COLMAR web portal presently consists of three servers: COLMAR covariance calculates the covariance NMR spectrum from an NMR input dataset, such as a TOCSY spectrum; COLMAR DemixC method decomposes the 2D covariance TOCSY spectrum into a reduced set of non-redundant 1D cross sections or traces, which belong to individual mixture components; COLMAR query screens the traces against a NMR spectral database to identify individual compounds. Examples are presented that illustrate the utility of this web server suite for complex mixture analysis. PMID:19634130

Zhang, Fengli; Robinette, Steve; Bruschweiler-Li, Lei; Brüschweiler, Rafael

2010-01-01

312

New developments and trends in NMR-ON  

NASA Astrophysics Data System (ADS)

New developments and new trends in NMR-ON are presented, especially in the context of precise measurements of nuclear magnetic moments and electric quadrupole moments of short-lived nuclei far off stability with on-line nuclear orientation techniques. The main emphasis is put on the following items: i) Quadrupole-interaction-resolved NMR-ON (QI-NMR-ON): It is shown that hcp-Co is an ideal matrix for precise measurements of electric quadrupole moments of radioactive nuclei in the region Hg, Au, Pt, Ir, Os. Recently, the first on-line experiment was performed successfully at NICOLE/ISOLDE-CERN and the very interesting quadrupole moment of186Au could be determined precisely. ii) General problems with lattice location and NMR-ON line widths in long decay chains, such as “lattice-site conservation” by implantation of a suitable precursor. iii) ?-decay-induced lattice site change. In the context of integral nuclear orientation measurements on nuclei far off stability, where the ?-decay energies become large, lattice site changes may occur, which make the interpretation of ?-anisotropies measured by integral and even time-differential techniques difficult or even impossible. A pilot experiment is described, in which such a ?-decay-induced lattice site change has been identified by a double-resonance NMR-ON measurement.

Hagn, E.

1992-11-01

313

Sensitive and robust electrophoretic NMR: instrumentation and experiments.  

PubMed

Although simple as a concept, electrophoretic NMR (eNMR) has so far failed to find wider application. Problems encountered are mainly due to disturbing and partly irreproducible convection-like bulk flow effects from both electro-osmosis and thermal convection. Additionally, bubble formation at the electrodes and rf noise pickup has constrained the typical sample geometry to U-tube-like arrangements with a small filling factor and a low resulting NMR sensitivity. Furthermore, the sign of the electrophoretic mobility cancels out in U-tube geometries. We present here a new electrophoretic sample cell based on a vertically placed conventional NMR sample tube with bubble-suppressing palladium metal as electrode material. A suitable radiofrequency filter design prevents noise pickup by the NMR sample coil from the high-voltage leads which extend into the sensitive sample volume. Hence, the obtained signal-to-noise ratio of this cell is one order of magnitude higher than that of our previous U-tube cells. Permitted by the retention of the sign of the displacement-related signal phase in the new cell design, an experimental approach is described where bulk flow effects by electro-osmosis and/or thermal convection are compensated through parallel monitoring of a reference signal from a non-charged species in the sample. This approach, together with a CPMG-like pulse train scheme provides a superior first-order cancellation of non-electrophoretic bulk flow effects. PMID:18289894

Hallberg, Fredrik; Furó, István; Yushmanov, Pavel V; Stilbs, Peter

2008-05-01

314

4 Kelvin Cryogenic Probe for 500 MHz NMR  

NASA Astrophysics Data System (ADS)

This paper describes the development of a 4 K cryogenic probe for 500 MHz Nuclear Magnetic Resonance (NMR) analyses. As thermal noise is proportional to the square root of the RF coil temperature, sensitivity of a 4 K probe is expected to be double that of conventional 25 K probes. The 4 K probe apparatus consists of a closed-cycle cooling system, a 5 m long helium transfer line and the NMR probe itself. The cooling system produces cold helium mist with a Gifford-McMahon/Joule-Thomson (GM/JT) cryocooler. The helium mist traverses the transfer line and then cools the RF coil. An acceptable power input of 3.6 W for the NMR pulse sequence was demonstrated, which was more than the time-averaged heat input, 2 W, generated by a multi-dimensional NMR pulse sequence. The basic NMR sensitivity of the cryogenic probe remains insufficient at present, but increasing B1xy (the field component in the xy plane generated by unit current of the RF coil) and decreasing the noise temperature of the preamplifier are promising approaches for achieving higher sensitivity in the future.

Yoshimoto, F.; Takahashi, M.; Horiuchi, T.; Hobo, F.; Inoue, K.; Miki, T.; Hamada, M.; Okamura, T.; Yokoyama, S.; Maeda, H.

2006-04-01

315

NMR of a Phospholipid: Modules for Advanced Laboratory Courses  

NASA Astrophysics Data System (ADS)

A laboratory project is described that builds upon the NMR experience undergraduates receive in organic chemistry with a battery of NMR experiments that investigate egg phosphatidylcholine (egg PC). This material, often labeled in health food stores as lecithin, is a major constituent of mammalian cell membranes. The NMR experiments may be used to make resonance assignments, to study molecular organization in model membranes, to test the effects of instrumental parameters, and to investigate the physics of nuclear spin systems. A suite of modular NMR exercises is described, so that the instructor may tailor the laboratory sessions to biochemistry, instrumental analysis, or physical chemistry. The experiments include solution-state one-dimensional (1D) 1H, 13C, and 31P experiments; two-dimensional (2D) TOtal Correlated SpectroscopY (TOCSY); and the spectral editing technique of Distortionless Enhancement by Polarization Transfer (DEPT). To demonstrate the differences between solution and solid-state NMR spectroscopy and instrumentation, a second set of experiments generates 1H, 13C, and 31P spectra of egg PC dispersed in aqueous solution, under both static and magic-angle spinning conditions.

Gaede, Holly C.; Stark, Ruth E.

2001-09-01

316

First Principles NMR Study of Fluorapatite under Pressure  

PubMed Central

NMR is the technique of election to probe the local properties of materials. Herein we present the results of density functional theory (DFT) ab initio calculations of the NMR parameters for fluorapatite (FAp), a calcium orthophosphate mineral belonging to the apatite family, by using the GIPAW method [Pickard and Mauri, 2001]. Understanding the local effects of pressure on apatites is particularly relevant because of their important role in many solid state and biomedical applications. Apatites are open structures, which can undergo complex anisotropic deformations, and the response of NMR can elucidate the microscopic changes induced by an applied pressure. The computed NMR parameters proved to be in good agreement with the available experimental data. The structural evaluation of the material behavior under hydrostatic pressure (from ?5 to +100 kbar) indicated a shrinkage of the diameter of the apatitic channel, and a strong correlation between NMR shielding and pressure, proving the sensitivity of this technique to even small changes in the chemical environment around the nuclei. This theoretical approach allows the exploration of all the different nuclei composing the material, thus providing a very useful guidance in the interpretation of experimental results, particularly valuable for the more challenging nuclei such as 43Ca and 17O. PMID:22770669

Pavan, Barbara; Ceresoli, Davide; Tecklenburg, Mary M. J.; Fornari, Marco

2012-01-01

317

Intermediate couplings: NMR at the solids-liquids interface  

NASA Astrophysics Data System (ADS)

Anisotropic interactions like dipolar couplings and chemical shift anisotropy have long offered solid-state NMR spectroscopists valuable structural information. Recently, solution-state NMR structural studies have begun to exploit residual dipolar couplings of biological molecules in weakly anisotropic solutions. These residual couplings are about 0.1% of the coupling magnitudes observed in the solid state, allowing simple, high-resolution NMR spectra to be retained. In this work, we examine the membrane-associated opioid, leucine enkephalin (lenk), in which the ordering is ten times larger than that for residual dipolar coupling experiments, requiring a combination of solution-state and solid-state NMR techniques. We adapted conventional solid-state NMR techniques like adiabatic cross- polarization and REDOR for use with such a system, and measured small amide bond dipolar couplings in order to determine the orientation of the amide bonds (and therefore the peptide) with respect to the membrane surface. However, the couplings measured indicate large structural rearrangements on the surface and contradict the published structures obtained by NOESY constraints, a reminder that such methods are of limited use in the presence of large-scale dynamics.

Spence, Megan

2006-03-01

318

NMR imaging and cryoporometry of swelling clays  

NASA Astrophysics Data System (ADS)

Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic strength as well as investigating the effect of the confining geometry and material surface properties seem to be worth to pursue. Acknowledgements: This work has been supported by the Swedish Nuclear Fuel and Waste Management Co (SKB) and the Swedish Research Council VR. References: [1] Dvinskikh S. V., Szutkowski K., Furó I. MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay. J. Magn. Reson. 198, 146 (2009). [2] Petrov O. V., Furó I. NMR cryoporometry: Principles, applications and potential. Prog. Nucl. Magn. Reson. Spec. 54, 97 (2009).

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

2010-05-01

319

NMR imaging of cell phone radiation absorption in brain tissue  

PubMed Central

A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance frequency shift of hydrogen protons in brain tissue. This proposed application of NMR thermometry offers sufficient spatial and temporal resolution to characterize the hot spots from absorbed cell phone radiation in aqueous media and biological tissues. Specific absorption rate measurements averaged over 1 mg and 10 s in the brain tissue cover the total absorption volume. Reference measurements with fiber optic temperature sensors confirm the accuracy of the NMR thermometry. PMID:23248293

Gultekin, David H.; Moeller, Lothar

2013-01-01

320

Solid State NMR and Protein-Protein Interactions in Membranes  

PubMed Central

Solid state NMR spectroscopy has evolved rapidly in recent years into an excellent tool for the characterization of membrane proteins and their complexes. In the past few years it has also become clear that the structure of membrane proteins, especially helical membrane proteins is determined, in part, by the membrane environment. Therefore, the modeling of this environment by a liquid crystalline lipid bilayer for solid state NMR has generated a unique tool for the characterization of native conformational states, local and global dynamics, and high resolution structure for these proteins. Protein-protein interactions can also benefit from this solid state NMR capability to characterize membrane proteins in a native-like environment. These complexes take the form of oligomeric structures and hetero-protein interactions both with water soluble proteins and other membrane proteins. PMID:24034903

Miao, Yimin; Cross, Timothy A.

2013-01-01

321

Deuterium NMR Studies of the Structure and Dynamics of Gramicidin.  

NASA Astrophysics Data System (ADS)

The structure and dynamics of the membrane peptide gramicidin are investigated by deuterium NMR. A specific structural and dynamical question about the peptide backbone of gramicidin is investigated by deuterating the alpha carbon of the third alanine residue. Deuterium NMR experiments performed on this analog in oriented lipid bilayers indicate that the c_alpha- ^2H bond makes an angle relative to the helical axis that is in agreement with the bond angle predicted by the beta^{6.3} helical model. A second structural and dynamical question about the peptide backbone of gramicidin is investigated by deuterating the formyl group of two different analogs. Deuterium NMR experiments performed on these analogs show that the spectra of the two analogs are very similar. However, the analog possessing D-leucine as the second residue also appears to exist in a second, minor conformation which does not seem to exist for the analog possessing glycine as the second residue.

Hing, Andrew William

1990-01-01

322

Advances in solid-state NMR of cellulose.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy is a well-established analytical and enabling technology in biofuel research. Over the past few decades, lignocellulosic biomass and its conversion to supplement or displace non-renewable feedstocks has attracted increasing interest. The application of solid-state NMR spectroscopy has long been seen as an important tool in the study of cellulose and lignocellulose structure, biosynthesis, and deconstruction, especially considering the limited number of effective solvent systems and the significance of plant cell wall three-dimensional microstructure and component interaction to conversion yield and rate profiles. This article reviews common and recent applications of solid-state NMR spectroscopy methods that provide insight into the structural and dynamic processes of cellulose that control bulk properties and biofuel conversion. PMID:24590189

Foston, Marcus

2014-06-01

323

NMR/MRI with hyperpolarized gas and high Tc SQUID  

DOEpatents

A method and apparatus for the detection of nuclear magnetic resonance (NMR) signals and production of magnetic resonance imaging (MRI) from samples combines the use of hyperpolarized inert gases to enhance the NMR signals from target nuclei in a sample and a high critical temperature (Tc) superconducting quantum interference device (SQUID) to detect the NMR signals. The system operates in static magnetic fields of 3 mT or less (down to 0.1 mT), and at temperatures from liquid nitrogen (77K) to room temperature. Sample size is limited only by the size of the magnetic field coils and not by the detector. The detector is a high Tc SQUID magnetometer designed so that the SQUID detector can be very close to the sample, which can be at room temperature.

Schlenga, Klaus (Eggenstein, DE); de Souza, Ricardo E. (Recife, BR); Wong-Foy, Annjoe (Berkeley, CA); Clarke, John (Berkeley, CA); Pines, Alexander (Berkeley, CA)

2000-01-01

324

Remote NMR/MRI detection of laser polarized gases  

DOEpatents

An apparatus and method for remote NMR/MRI spectroscopy having an encoding coil with a sample chamber, a supply of signal carriers, preferably hyperpolarized xenon and a detector allowing the spatial and temporal separation of signal preparation and signal detection steps. This separation allows the physical conditions and methods of the encoding and detection steps to be optimized independently. The encoding of the carrier molecules may take place in a high or a low magnetic field and conventional NMR pulse sequences can be split between encoding and detection steps. In one embodiment, the detector is a high magnetic field NMR apparatus. In another embodiment, the detector is a superconducting quantum interference device. A further embodiment uses optical detection of Rb--Xe spin exchange. Another embodiment uses an optical magnetometer using non-linear Faraday rotation. Concentration of the signal carriers in the detector can greatly improve the signal to noise ratio.

Pines, Alexander; Saxena, Sunil; Moule, Adam; Spence, Megan; Seeley, Juliette A.; Pierce, Kimberly L.; Han, Song-I; Granwehr, Josef

2006-06-13

325

Development of a new device control system for ?-NMR experiments  

NASA Astrophysics Data System (ADS)

We have developed a device-control system of a ?-NMR apparatus for the measurement of nuclear electromagnetic nuclear moments of rare isotopes. In this development, we installed fast relay switches into a high-power tank circuit in order to apply a strong oscillating magnetic field and to sweep its frequency as wide as possible. The system enables to conduct NMR frequency scans with wide frequency windows by dynamically changing the tank-circuit resonant frequency. Furthermore, logical electric-circuit modules of the data taking system were replaced by a programmable logic module. The system performance was evaluated in the ?-NMR experiments conducted at the RIBF facility using 20F and 33Cl radioactive isotopes.

Yoshida, N.; Ueno, H.; Yoshimi, A.; Ishibashi, Y.; Ichikawa, Y.; Abe, Y.; Asahi, K.; Chikamori, M.; Fujita, T.; Furukawa, T.; Hikota, E.; Nagae, D.; Ohtomo, Y.; Saito, Y.; Shirai, H.; Suzuki, T.; Yang, X. F.

2013-12-01

326

Toroid cavity/coil NMR multi-detector  

DOEpatents

An analytical device for rapid, non-invasive nuclear magnetic resonance (NMR) spectroscopy of multiple samples using a single spectrometer is provided. A modified toroid cavity/coil detector (TCD), and methods for conducting the simultaneous acquisition of NMR data for multiple samples including a protocol for testing NMR multi-detectors are provided. One embodiment includes a plurality of LC resonant circuits including spatially separated toroid coil inductors, each toroid coil inductor enveloping its corresponding sample volume, and tuned to resonate at a predefined frequency using a variable capacitor. The toroid coil is formed into a loop, where both ends of the toroid coil are brought into coincidence. Another embodiment includes multiple micro Helmholtz coils arranged on a circular perimeter concentric with a central conductor of the toroid cavity.

Gerald, II, Rex E. (Brookfield, IL); Meadows, Alexander D. (Indianapolis, IN); Gregar, Joseph S. (Naperville, IL); Rathke, Jerome W. (Homer Glen, IL)

2007-09-18

327

Detection of free chloride in concrete by NMR  

SciTech Connect

Laboratory experiments to detect chloride in a cement matrix using pulse nuclear magnetic resonance (NMR) were conducted. The coils were in the centimeter scale and the magnetic field was 2.35 T. NMR signals were obtained from both aqueous chloride solution and samples of both regular and white Portland cement (WPC). A concrete sample from a sidewalk that had been in the field for 20 years was also tested. The experiments demonstrated that the signal-to-noise ratio (SNR) for a centimeter-scale cement sample volume is so small, even after averaging, that sample volumes much lower than that are unlikely to produce measurable signals at fields of 1 T or below. The consequence is that the potential for realizing an embedded NMR-based sensor including the magnet is low. Parametric studies identify feasible alternative coil diameters and magnetic field strengths for detecting chloride ion concentrations in hardened concrete.

Yun Haebum; Patton, Mark E.; Garrett, James H.; Fedder, Gary K.; Frederick, Kevin M.; Hsu, J.-J.; Lowe, Irving J.; Oppenheim, Irving J.; Sides, Paul J

2004-03-01

328

NMR-Metabolic Methodology in the Study of GM Foods  

PubMed Central

The 1H-NMR methodology used in the study of genetically modified (GM) foods is discussed. Transgenic lettuce (Lactuca sativa cv "Luxor") over-expressing the ArabidopsisKNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars) present in leaves of conventional and GM lettuce were monitored by NMR and quantified at two developmental stages. The NMR spectra did not reveal any difference in metabolite composition between the GM lettuce and the wild type counterpart. Statistical analyses of metabolite variables highlighted metabolism variation as a function of leaf development as well as the transgene. A main effect of the transgene was in altering sugar metabolism. PMID:22253988

Sobolev, Anatoly P.; Capitani, Donatella; Giannino, Donato; Nicolodi, Chiara; Testone, Giulio; Santoro, Flavio; Frugis, Giovanna; Iannelli, Maria A.; Mattoo, Autar K.; Brosio, Elvino; Gianferri, Raffaella; D’Amico, Irene; Mannina, Luisa

2010-01-01

329

Mobile sensor for high resolution NMR spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

In this work we describe the construction of a mobile NMR tomograph with a highly homogeneous magnetic field. Fast MRI techniques as well as NMR spectroscopy measurements were carried out. The magnet is based on a Halbach array built from identical permanent magnet blocks generating a magnetic field of 0.22 T. To shim the field inhomogeneities inherent to magnet arrays constructed from these materials, a shim strategy based on the use of movable magnet blocks is employed. With this approach a reduction of the line-width from ˜20 kHz to less than 0.1 kHz was achieved, that is by more than two orders of magnitude, in a volume of 21 cm 3. Implementing a RARE sequence, 3D images of different objects placed in this volume were obtained in short experimental times. Moreover, by reducing the sample size to 1 cm 3, sub ppm resolution is obtained in 1H NMR spectra.

Danieli, Ernesto; Mauler, Jörg; Perlo, Juan; Blümich, Bernhard; Casanova, Federico

2009-05-01

330

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

SciTech Connect

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

Krishnan, V V

2005-04-26

331

NMR study of black-phase in SmS  

NASA Astrophysics Data System (ADS)

We report the result of the 33S nuclear magnetic resonance (NMR) measurement on the nonmagnetic semiconductor SmS at ambient pressure. For this measurement, the 33S isotope enriched powder sample of SmS was prepared to increase the 33S NMR intensity. We have attempted 33S NMR measurement on SmS and successfully observed the signal of it. With decreasing temperature, the spectrum measured at the constant magnetic field shifted to lower frequency and became weakly temperature dependent below 50 K. The presence of the energy gap was microscopically established by the rapid decrease in the nuclear spin-lattice relaxation rate 1/T1. The activation energy was deduced to be 625 K from an Arrhenius plot of T1.

Koyama, T.; Yamada, H.; Ueda, K.; Mito, T.; Haga, Y.

2015-03-01

332

Quantitating metabolites in protein precipitated serum using NMR spectroscopy.  

PubMed

Quantitative NMR-based metabolite profiling is challenged by the deleterious effects of abundant proteins in the intact blood plasma/serum, which underscores the need for alternative approaches. Protein removal by ultrafiltration using low molecular weight cutoff filters thus represents an important step. However, protein precipitation, an alternative and simple approach for protein removal, lacks detailed quantitative assessment for use in NMR based metabolomics. In this study, we have comprehensively evaluated the performance of protein precipitation using methanol, acetonitrile, perchloric acid, and trichloroacetic acid and ultrafiltration approaches using 1D and 2D NMR, based on the identification and absolute quantitation of 44 human blood metabolites, including a few identified for the first time in the NMR spectra of human serum. We also investigated the use of a "smart isotope tag," (15)N-cholamine for further resolution enhancement, which resulted in the detection of a number of additional metabolites. (1)H NMR of both protein precipitated and ultrafiltered serum detected all 44 metabolites with comparable reproducibility (average CV, 3.7% for precipitation; 3.6% for filtration). However, nearly half of the quantified metabolites in ultrafiltered serum exhibited 10-74% lower concentrations; specifically, tryptophan, benzoate, and 2-oxoisocaproate showed much lower concentrations compared to protein precipitated serum. These results indicate that protein precipitation using methanol offers a reliable approach for routine NMR-based metabolomics of human blood serum/plasma and should be considered as an alternative to ultrafiltration. Importantly, protein precipitation, which is commonly used by mass spectrometry (MS), promises avenues for direct comparison and correlation of metabolite data obtained from the two analytical platforms to exploit their combined strength in the metabolomics of blood. PMID:24796490

Nagana Gowda, G A; Raftery, Daniel

2014-06-01

333

NMR imaging of fluid dynamics in reservoir core.  

PubMed

A medical NMR imaging instrument has been modified to image water and oil in reservoir rocks by the construction of a new receiving coil. Both oil and water inside the core produced readily detectable proton NMR signals, while the rock matrix produced no signal. Because of similar T2 NMR relaxation times, the water was doped with a paramagnetic ion, Mn+2, to reduce its T2 relaxation time. This procedure enhanced the separation between the oil and water phases in the resulting images. Sequential measurements, as water imbibed into one end and oil was expelled from the other end of a core plug, produced a series of images which showed the dynamics of the fluids. For water-wet Berea Sandstone a flood front was readily observed, but some of the oil was apparently left behind in small, isolated pockets which were larger than individual pores. After several additional pore volumes of water flowed through the plug the NMR image indicated a homogeneous distribution of oil. The amount of residual oil, as determined from the ratio of NMR intensities, closely approximated the residual oil saturation of fully flooded Berea samples measured by Dean-Stark extraction. A Berea sandstone core treated to make it partially oil-wet, did not show a definitive flood front, but appeared to channel the water around the perimeter of the core plug. The relative ease with which these images were made indicates that NMR imaging can be a useful technique to follow the dynamics of oil and water through a core plug for a variety of production processes. PMID:3226235

Baldwin, B A; Yamanashi, W S

1988-01-01

334

An analytical methodology for magnetic field control in unilateral NMR.  

PubMed

Traditionally, unilateral NMR systems such as the NMR-MOUSE have used the fringe field between two bar magnets joined with a yoke in a 'U' geometry. This allows NMR signals to be acquired from a sensitive volume displaced from the magnets, permitting large samples to be investigated. The drawback of this approach is that the static field (B0) generated in this configuration is inhomogeneous, and has a large, nonlinear, gradient. As a consequence, the sensitive volume of the instrument is both small and ill defined. Empirical redesign of the permanent magnet array producing the B0 field has yielded instruments with magnetic field topologies acceptable for varying applications. The drawback of current approaches is the lack of formalism in the control of B0. Rather than tailoring the magnet geometry to NMR investigations, measurements must be tailored to the available magnet geometry. In this work, we present a design procedure whereby the size, shape, field strength, homogeneity, and gradients in the sensitive spot of a unilateral NMR sensor can be controlled. Our design uses high permeability pole pieces, shaped according to the contours of an analytical expression, to control B0, allowing unilateral NMR instruments to be designed to generate a controlled static field topology. We discuss the approach in the context of previously published design techniques, and explain the advantages inherent in our strategy as compared to other optimization methods. We detail the design, simulation, and construction of a unilateral magnet array using our approach. It is shown that the fabricated array exhibits a B0 topology consistent with the design. The utility of the design is demonstrated in a sample nondestructive testing application. Our design methodology is general, and defines a class of unilateral permanent magnet arrays in which the strength and shape of B0 within the sensitive volume can be controlled. PMID:15809175

Marble, Andrew E; Mastikhin, Igor V; Colpitts, Bruce G; Balcom, Bruce J

2005-05-01

335

Experimental quantum deletion in an NMR quantum information processor  

NASA Astrophysics Data System (ADS)

We report an NMR experimental realization of a rapid quantum deletion algorithm that deletes marked states in an unsorted database. Unlike classical deletion, where search and deletion are equivalent, quantum deletion can be implemented with only a single query, which achieves exponential speed-up compared to the optimal classical analog. In the experimental realization, the GRAPE algorithm was used to obtain an optimized NMR pulse sequence, and the efficient method of maximum-likelihood has been used to reconstruct the experimental output state.

Long, Yu; Feng, GuanRu; Pearson, Jasong; Long, GuiLu

2014-07-01

336

Sensitivity enhancement in solution NMR: Emerging ideas and new frontiers  

NASA Astrophysics Data System (ADS)

Modern NMR spectroscopy has reached an unprecedented level of sophistication in the determination of biomolecular structure and dynamics at atomic resolution in liquids. However, the sensitivity of this technique is still too low to solve a variety of cutting-edge biological problems in solution, especially those that involve viscous samples, very large biomolecules or aggregation-prone systems that need to be kept at low concentration. Despite the challenges, a variety of efforts have been carried out over the years to increase sensitivity of NMR spectroscopy in liquids. This review discusses basic concepts, recent developments and future opportunities in this exciting area of research.

Lee, Jung Ho; Okuno, Yusuke; Cavagnero, Silvia

2014-04-01

337

Sensitivity Enhancement in Solution NMR: Emerging Ideas and New Frontiers  

PubMed Central

Modern NMR spectroscopy has reached an unprecedented level of sophistication in the determination of biomolecular structure and dynamics at atomic resolution in liquids. However, the sensitivity of this technique is still too low to solve a variety of cutting-edge biological problems in solution, especially those that involve viscous samples, very large biomolecules or aggregation-prone systems that need to be kept at low concentration. Despite the challenges, a variety of efforts have been carried out over the years to increase sensitivity of NMR spectroscopy in liquids. This review discusses basic concepts, recent developments and future opportunities in this exciting area of research. PMID:24656077

Lee, Jung Ho; Okuno, Yusuke; Cavagnero, Silvia

2014-01-01

338

MVAPACK: A Complete Data Handling Package for NMR Metabolomics  

PubMed Central

Data handling in the field of NMR metabolomics has historically been reliant on either in-house mathematical routines or long chains of expensive commercial software. Thus, while the relatively simple biochemical protocols of metabolomics maintain a low barrier to entry, new practitioners of metabolomics experiments are forced to either purchase expensive software packages or craft their own data handling solutions from scratch. This inevitably complicates the standardization and communication of data handling protocols in the field. We report a newly developed open-source platform for complete NMR metabolomics data handling, MVAPACK, and describe its application on an example metabolic fingerprinting data set. PMID:24576144

2015-01-01

339

[DNA-phospholipid interaction. 31P-NMR study].  

PubMed

The phage T7 DNA complexes with various phospholipids (PL) were studied by 31P NMR at PL/nucleotide molar ratio of 2 : 1. Using a phosphatidylcholine thion analogue, the contributions of PL and DNA into the 31P NMR spectrum of the complex were estimated. It was found that PL-DNA interaction results in partial immobilizing ability of PL depends on their structure, increasing in the following row: phosphatidylcholine-phosphatidylethanolamine less than sphingomyelin less than or equal to ternary mixture of these PL. The data obtained are indicative of nonequivalent binding of DNA with various PL species. PMID:6497914

Viktorov, A V; Grepachevski?, A A; Bergel'son, L D

1984-07-01

340

NMR, XRD and IR study on microcrystalline opals  

Microsoft Academic Search

Microcrystalline opal-CT and opal-C were investigated by 29Si MAS NMR and 29Si {1H} cross polarisation MAS NMR spectroscopy, X-ray small angle scattering, X-ray powder diffraction and infrared absorption\\u000a spectroscopy. The results are compared with those for non-crystalline precious opal (opal-AG), non-crystalline hyalite (opal-AN),\\u000a moderately disordered cristobalite and with well ordered low-cristobalite and low-tridymite. Opal-C is confirmed to be strongly\\u000a stacking

H. Graetsch; H. Gies; I. Topalovi?

1994-01-01

341

MVAPACK: a complete data handling package for NMR metabolomics.  

PubMed

Data handling in the field of NMR metabolomics has historically been reliant on either in-house mathematical routines or long chains of expensive commercial software. Thus, while the relatively simple biochemical protocols of metabolomics maintain a low barrier to entry, new practitioners of metabolomics experiments are forced to either purchase expensive software packages or craft their own data handling solutions from scratch. This inevitably complicates the standardization and communication of data handling protocols in the field. We report a newly developed open-source platform for complete NMR metabolomics data handling, MVAPACK, and describe its application on an example metabolic fingerprinting data set. PMID:24576144

Worley, Bradley; Powers, Robert

2014-05-16

342

31P NMR spectroscopy of in vivo tumors  

NASA Astrophysics Data System (ADS)

A probe, suitable for any wide-bore NMR spectrometer, was constructed for monitoring high-resolution spectra of in vivo subcutaneously implanted tumors in mice. Preliminary studies of a variety of murine tumors (MOPC 104E myeloma, Dunn osteosarcoma, colon-26, ovarian M5, and mammary adenocarcinoma as well as human colon, mammary, and lung tumors in athymic mice) indicate that the 31P NMR spectrum is a sensitive monitor of progressive metabolic changes that occur during untreated tumor growth and an early indicator of tumor response to chemotherapy, hyperthermia, and X radiation. Response to each of these therapeutic modalities is accompanied by distinctly different spectral changes.

Ng, T. C.; Evanochko, W. T.; Hiramoto, R. N.; Ghanta, V. K.; Lilly, M. B.; Lawson, A. J.; Corbett, T. H.; Durant, J. R.; Glickson, J. D.

343

High field DNP and cryogenic MAS NMR : novel instrumentation and applications  

E-print Network

Solid State Nuclear Magnetic Resonance (ssNMR) spectroscopy has blossomed over the last two decades. As ssNMR is progressively applied to more challenging systems, the sensitivity remains one of its major limiting factors. ...

Markhasin, Evgeny

2014-01-01

344

Nuclear Magnetic Resonance (NMR) is the only logging technique available to estimate pore-size  

E-print Network

1 ABSTRACT Nuclear Magnetic Resonance (NMR) is the only logging technique available to estimate, Nuclear Magnetic Resonance (NMR) logging has been used to assess a handful of key petrophysical parameters

Torres-Verdín, Carlos

345

Dynamic nuclear polarization in biomolecular solid state NMR : methods and applications in peptides and membrane proteins  

E-print Network

Solid state NMR can probe structure and dynamics on length scales from the atomic to the supramolecular. However, low sensitivity limits its application in macromolecules. NMR sensitivity can be improved by dynamic nuclear ...

Bajaj, Vikram Singh

2007-01-01

346

Neuronal Tracing with Magnetic Labels: NMR Imaging Methods, Preliminary Results, and New Optimized Coils  

Microsoft Academic Search

The investigations focussed on in vivo NMR imaging studies of magnetic particles with and within neural cells. NMR imaging methods, both Fourier transform and projection reconstruction, were implemented and new protocols were developed to perform \\

Pratik Ghosh

1992-01-01

347

Electrical noise model for detection circuitry of an NMR-based formation evaluation Tool  

E-print Network

The RF signals received from Nuclear Magnetic Resonance (NMR) measurements in logging while drilling NMR instruments are often of the same amplitude as the noise generated by the instruments. Designers of these devices are ...

Maison, Julie Laure K

2011-01-01

348

Optimization of THz Wave Coupling into Samples in DNP/NMR Spectroscopy  

E-print Network

High power millimeter wave and terahertz sources are used in DNP/NMR spectroscopy to greatly enhance the NMR signal. A key issue is the efficient coupling of the source power to the sample. We present HFSS calculations ...

Barnes, Alexander

349

De-noising methods for NMR logging echo signals based on wavelet transform  

NASA Astrophysics Data System (ADS)

The signal-to-noise ratio (SNR) of the echo signals in nuclear magnetic resonance (NMR) is one of the most important factors that affect the effective application of NMR logging. Wavelet transform can be used to remove the noise and improve the SNR of echo signals in NMR logging. This paper uses three de-noising methods to treat the NMR echo signals: modulus maxima, spatial correlation and wavelet threshold based on wavelet transform. The effects of the three methods in the noise reduction of NMR echo signals were compared by numerical simulation, core experiment and NMR logging data. The results show that while these three methods can all effectively improve the SNR of NMR echo signals and the NMR T2 inversion results, the most effective among them is the wavelet threshold method, which can obtain a higher SNR and provides more accurate formation porosity.

Xie, Ranhong; Wu, Youbin; Liu, Kang; Liu, Mi; Xiao, Lizhi

2014-06-01

350

Assigning the NMR Spectrum of Glycidol: An Advanced Organic Chemistry Exercise  

ERIC Educational Resources Information Center

Various one- and two-dimensional NMR experiments have been found to be extremely useful for assigning the proton and carbon NMR spectra of glycidol. The technique provides extremely valuable information aiding in the complete assignment of the peaks.

Helms, Eric; Arpaia, Nicholas; Widener, Melissa

2007-01-01

351

COMPREHENSIVE PROGRESS REPORT FOR FOURIER TRANSFORM NMR (NUCLEAR MAGNETIC RESONANCE) OF METALS OF ENVIRONMENTAL SIGNIFICANCE  

EPA Science Inventory

Interactions of the metals cadmium and selenium with various biologically important substrates were studied by nuclear magnetic resonance (NMR) spectroscopy. Cadmium-113 NMR was used for a critical examination of three metalloproteins: concanavalin A, bovine superoxide dismutase ...

352

ARIA2: Automated NOE assignment and data integration in NMR structure calculation  

Microsoft Academic Search

Summary:Modernstructuralgenomicsprojectsdemandforintegrated methods for the interpretation and storage of nuclear magnetic resonance (NMR) data. Here we present version 2.1 of our program ARIA (Ambiguous Restraints for Iterative Assignment) for automated assignmentofnuclearOverhauserenhancement(NOE)dataandNMR structurecalculation.Wereportonrecentdevelopments,mostnotablya graphical user interface, and the incorporation of the object-oriented data model of the Collaborative Computing Project for NMR (CCPN). The CCPN data model defines a storage model for NMR

Wolfgang Rieping; Michael Habeck; Benjamin Bardiaux; Aymeric Bernard; Therese E. Malliavin; Michael Nilges

2007-01-01

353

Solid state NMR studies of covalent graphite fluorides (CF) n and (C 2F) n  

Microsoft Academic Search

Various covalent graphite fluorides were studied using solid state nuclear magnetic resonance (NMR). 19F magic angle spinning (MAS) NMR, 13C MAS NMR and 13C MAS NMR with 19F to 13C Cross Polarization (CP) allow both the presence of CF and CF2 groups and the carbon atoms hybridization, sp2 or sp3, to be determined. 19F spin–lattice relaxation time T1 of the

Jérôme Giraudet; Marc Dubois; Katia Guérin; André Hamwi; Francis Masin

2006-01-01

354

Alginate monomer composition studied by solution- and solid-state NMR – A comparative chemometric study  

Microsoft Academic Search

The potential of using 1H high-resolution (HR) magic angle spinning (MAS) nuclear magnetic resonance (NMR) of alginates suspended in D2O or 13C cross-polarisation (CP) MAS NMR of alginate powders as an alternative method to the traditional 1H solution-state NMR method for the analysis of the alginate monomer composition (mannuronate (M)\\/guluronate (G) ratio) has been investigated. The MAS NMR experiments can

Tina Salomonsen; Henrik Max Jensen; Flemming Hofmann Larsen; Stefan Steuernagel; Søren Balling Engelsen

2009-01-01

355

NMR STUDIES OF THE GLYCOPROTEIN CYTOPLASMIC TAILS OF HANTAVIRUS AND CRIMEAN CONGO HEMORRHAGIC FEVER VIRUS  

E-print Network

Chapter 3. NMR Structure of the Andes Zinc Finger Domain A. Introduction 30 B. Protein Expression Results 32 C. Zn2+ EDTA Titration 33 D. NMR Structure Determination 34 E. Description of the Back-to-back CCHC ZF Fold... Results 57 C. PHV Gn Tail Also Relies on Zn2+ for Proper Folding 57 D. Backbone NMR Assignments 59 E. Modeling of the PHV Gn Zinc Finger Domain 60 F. Discussion 60 G. References 64 Chapter 5. NMR Structure...

Estrada, David Fernando

2011-04-25

356

Solid-State Dipolar INADEQUATE NMR Spectroscopy with a Large Double-Quantum Spectral Width  

E-print Network

Solid-State Dipolar INADEQUATE NMR Spectroscopy with a Large Double-Quantum Spectral Width Mei Hong Academic Press Key Words: solid-state NMR; INADEQUATE; double-quan- tum; C7; dipolar recoupling. Recently, solid-state homonuclear double-quantum NMR spec- troscopy has been increasingly employed to obtain

Hong, Mei

357

Physica B 378380 (2006) 10601061 NMR studies of incommensurate quantum antiferromagnetic  

E-print Network

structure of spin­chain compound LiCuVO4 single crystals using NMR. The structure of LiCuVO4 [1, the application of the local methods such as NMR enables one to obtain the crucial information for solving this problem. 51 V NMR and spin-lattice relaxation measurements were carried out in the wide temperature range

Weston, Ken

2006-01-01

358

NVR-BIP: Nuclear vector replacement using binary integer programming for NMR structure-based assignments  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) spectroscopy is an important experimental technique that allows one to study protein structure in solution and to identify important sites in a protein. An important bottleneck in NMR protein structure determination is the assignment of NMR peaks to the corresponding nuclei. Structure-based assignment (SBA) aims to solve this problem with the help of a template protein

Mehmet Serkan Apaydin; Bülent Çatay; Nicholas Patrick; Bruce R. Donald

2009-01-01

359

SOLID-STATE 3'P NMR SPECTROSCOPY OF BACTERIOPHAGE MI3 AND  

E-print Network

SOLID-STATE 3'P NMR SPECTROSCOPY OF BACTERIOPHAGE MI3 AND TOBACCO MOSAIC VIRUS Pieter Magusin #12;#12;SOLID-STATE 31P NMR SPECTROSCOPY OF BACTERIOPHAGE MI3 AND TOBACCO MOSAIC VIRUS #12;Promotor: dr. T vakgroep Moleculaire Fysica #12;Pieter Magusin SOLID-STATE 31P NMR SPECTROSCOPY OF BACTERIOPHAGE MI3

Hemminga, Marcus A.

360

DEVELOPMENT OF MULTIPLE SAMPLE SOLID-STATE NMR PROBES FOR ANALYSIS OF PHARMACEUTICAL COMPOUNDS AND FORMULATIONS  

E-print Network

Solid-state NMR spectroscopy (ssNMR) is an extremely powerful technique for the analysis of pharmaceutical dosage forms. A major limitation of ssNMR is the number of samples that can be analyzed in a given period of time. ...

Nelson, Benjamin Nels

2011-12-31

361

The study of structure and dynamics of molecules: NMR spectra transformed by superfine coupling.  

PubMed

In the present paper, the peculiarities of NMR phenomenon in paramagnetic systems are reported. Specifics of detection of high-resolution NMR spectra transformed by superfine interaction are discussed. Concrete examples illustrate the modern possibilities of NMR application for the study of structure and dynamics of the molecular (multielectron) systems. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25585862

Voronov, Vladimir K

2015-03-01

362

A Review of the Principles and Applications of the NMR Technique for Near-Surface Characterization  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive review of the recent advances in nuclear magnetic resonance (NMR) measurements for near-surface characterization using laboratory, borehole, and field technologies. During the last decade, NMR has become increasingly popular in near-surface geophysics due to substantial improvements in instrumentation, data processing, forward modeling, inversion, and measurement techniques. This paper starts with a description of the principal theory and applications of NMR. It presents a basic overview of near-surface NMR theory in terms of its physical background and discusses how NMR relaxation times are related to different relaxation processes occurring in porous media. As a next step, the recent and seminal near-surface NMR developments at each scale are discussed, and the limitations and challenges of the measurement are examined. To represent the growth of applications of near-surface NMR, case studies in a variety of different near-surface environments are reviewed and, as examples, two recent case studies are discussed in detail. Finally, this review demonstrates that there is a need for continued research in near-surface NMR and highlights necessary directions for future research. These recommendations include improving the signal-to-noise ratio, reducing the effective measurement dead time, and improving production rate of surface NMR (SNMR), reducing the minimum echo time of borehole NMR (BNMR) measurements, improving petrophysical NMR models of hydraulic conductivity and vadose zone parameters, and understanding the scale dependency of NMR properties.

Behroozmand, Ahmad A.; Keating, Kristina; Auken, Esben

2015-01-01

363

A Review of the Principles and Applications of the NMR Technique for Near-Surface Characterization  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive review of the recent advances in nuclear magnetic resonance (NMR) measurements for near-surface characterization using laboratory, borehole, and field technologies. During the last decade, NMR has become increasingly popular in near-surface geophysics due to substantial improvements in instrumentation, data processing, forward modeling, inversion, and measurement techniques. This paper starts with a description of the principal theory and applications of NMR. It presents a basic overview of near-surface NMR theory in terms of its physical background and discusses how NMR relaxation times are related to different relaxation processes occurring in porous media. As a next step, the recent and seminal near-surface NMR developments at each scale are discussed, and the limitations and challenges of the measurement are examined. To represent the growth of applications of near-surface NMR, case studies in a variety of different near-surface environments are reviewed and, as examples, two recent case studies are discussed in detail. Finally, this review demonstrates that there is a need for continued research in near-surface NMR and highlights necessary directions for future research. These recommendations include improving the signal-to-noise ratio, reducing the effective measurement dead time, and improving production rate of surface NMR (SNMR), reducing the minimum echo time of borehole NMR (BNMR) measurements, improving petrophysical NMR models of hydraulic conductivity and vadose zone parameters, and understanding the scale dependency of NMR properties.

Behroozmand, Ahmad A.; Keating, Kristina; Auken, Esben

2014-09-01

364

NMR STUDIES OF LIQUID CRYSTALS AND MOLECULES DISSOLVED IN LIQUID CRYSTAL SOLVENTS  

Microsoft Academic Search

This thesis describes several studies in which nuclear magnetic resonance (nmr) spectroscopy has been used to probe the structure, orientation and dynamics of liquid crystal mesogens and molecules dissolved in liquid crystalline phases. In addition, a modern high field nmr spectrometer is described which has been used to perform such nmr studies. Chapter 1 introduces the quantum mechanical formalisms used

Drobny

1982-01-01

365

ORGANIC PHOSPHORUS COMPOSITION AND POTENTIAL BIOAVAILABILITY IN SEMI-ARID ARABLE SOILS OF THE WESTERN UNITED STATES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The organic P composition of semi-arid arable soils is largely unknown, but such information is fundamental to understanding P dynamics in irrigated agriculture. We used phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and phosphatase hydrolysis to characterize organic P in semi-arid ara...

366

Phosphorus-containing podands. Synthesis of neutral and acidic monopodands based on. cap alpha. -monophosphinylalkylated pyrocatechols  

SciTech Connect

Monopodands with phosphonate (neutral and acidic) and phosphine oxide terminal groups were obtained by the reaction of salts of mono-alpha-phosphinylalkylated pyrocatechols with oligoethylene glycols ditosylates and their analogs. A comprehensive chemical analysis of the reactions and their products, including hydrogen 1 and phosphorus 31 NMR spectra performed in a variety of deuterated solvents, is conducted.

Bovin, A.N.; Degtyarev, A.N.; Tsvetkov, E.N.

1987-06-20

367

Alterations in phosphate metabolism during cellular recovery of radiation damage in yeast  

Microsoft Academic Search

Alterations were examined in phosphate pools during cellular recovery from radiation damage in intact, wild-type diploid yeast cells using phosphorus 31 nuclear magnetic resonance (NMR) spectroscopy. Concurrent cell survival analysis was determined following exposure to cobalt 60 gamma radiation. Cells held in citrate-buffered saline (CBS) showed increased survival with increasing time after irradiation (liquid holding recovery, LHR) with no further

Patricia K. Holahan; Steven A. Knizner; Caroline M. Gabriel; Charles E. Swenberg

1988-01-01

368

Anti-flammable properties of capable phosphorus-nitrogen containing triazine derivatives on cotton  

Technology Transfer Automated Retrieval System (TEKTRAN)

Most of new phosphorus-nitrogen containing compounds were prepared by organic reactions of cyanuric chloride and phosphonates. They were characterized by analytical tools such as proton (1H), carbon (13C), and phosphorus (31P) nuclear magnetic resonance (NMR) spectroscopy and elemental analysis (EA)...

369

Protein Loop Closure Using Orientational Restraints from NMR Data  

E-print Network

determination problem as a system of low-degree polynomial equations that can be solved exactly and in closedProtein Loop Closure Using Orientational Restraints from NMR Data Chittaranjan Tripathy1 , Jianyang the 3D structures of loops using global orientational restraints on internuclear vectors, such as those

Zeng, Jianyang "Michael"

370

3D structural homology detection via NMR resonance assignment  

Microsoft Academic Search

One goal of the structural genomics initiative is the identification of new protein folds. Sequence-based structural homology prediction methods are an important means for prioritizing unknown proteins for structure determination. However, an important challenge remains: two highly dissimilar sequences can have similar folds - how can we detect this rapidly, in the context of structural genomics? High-throughput NMR experiments, coupled

Christopher James Langmead; Bruce Randall Donald

2004-01-01

371

Structural NMR of Protein Oligomers using Hybrid Methods  

PubMed Central

Solving structures of native oligomeric protein complexes using traditional high resolution NMR techniques remains challenging. However, increased utilization of computational platforms, and integration of information from less traditional NMR techniques with data from other complementary biophysical methods, promises to extend the boundary of NMR-applicable targets. This article reviews several of the techniques capable of providing less traditional and complementary structural information. In particular, the use of orientational constraints coming from residual dipolar couplings and residual chemical shift anisotropy offsets are shown to simplify the construction of models for oligomeric complexes, especially in cases of weak homo-dimers. Combining this orientational information with interaction site information supplied by computation, chemical shift perturbation, paramagnetic surface perturbation, cross-saturation and mass spectrometry allows high resolution models of the complexes to be constructed with relative ease. Non-NMR techniques, such as mass spectrometry, EPR and small angle X-ray scattering, are also expected to play increasingly important roles by offering alternative methods of probing the overall shape of the complex. Computational platforms capable of integrating information from multiple sources in the modeling process are also discussed in the article. And finally a new, detailed example on the determination of a chemokine tetramer structure will be used to illustrate how a non-traditional approach to oligomeric structure determination works in practice. PMID:21074622

Wang, Xu; Lee, Hsiau-Wei; Liu, Yizhou; Prestegard, James H.

2010-01-01

372

Amplification of Xenon NMR and MRI by remote detection  

SciTech Connect

A novel technique is proposed in which a nuclear magneticresonance (NMR) spectrum or magnetic resonance image (MRI) is encoded andstored as spin polarization and is then moved to a different physicallocation to be detected. Remote detection allows the separateoptimization of the encoding and detection steps, permitting theindependent choice of experimental conditions, and excitation anddetection methodologies. In the first experimental demonstration of thistechnique, we show that NMR signal can be amplified by taking diluted129Xe from a porous sample placed inside a large encoding coil, andconcentrating it into a smaller detection coil. In general, the study ofNMR active molecules at low concentration that have low physical fillingfactor is facilitated by remote detection. In the second experiment, MRIinformation encoded in a very low field magnet (4-7mT) is transferred toa high field magnet (4.2 T) in order to be detected under optimizedconditions. Furthermore, remote detection allows the utilization ofultra-sensitive optical or superconducting detection techniques, whichbroadens the horizon of NMR experimentation.

Moule, Adam J.; Spence, Megan M.; Han, Song-I.; Seeley, JulietteA.; Pierce, Kimberly L.; Saxena, Sunil; Pines, Alexander

2003-03-31

373

Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization  

PubMed Central

The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors. PMID:14602624

Lens, Piet N. L.; Gastesi, Rakel; Vergeldt, Frank; van Aelst, Adriaan C.; Pisabarro, Antonio G.; Van As, Henk

2003-01-01

374

Studies on supramolecular gel formation using DOSY NMR.  

PubMed

Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential DOSY processing, and the results were compared with the automated Bayesian DOSY transformation to obtain 2D plots. Our results provide useful information on the stepwise self-assembly of small molecules leading to gelation. We believe that the results obtained from these experiments are applicable in determining the CGC and gel melting temperatures of supramolecular gels. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25631685

Nonappa; Šaman, David; Kolehmainen, Erkki

2015-04-01

375

NMR of thin layers using a meanderline surface coil  

DOEpatents

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Cowgill, Donald F. (San Ramon, CA)

2001-01-01

376

Ceramic cells for high pressure NMR spectroscopy of proteins  

Microsoft Academic Search

Application of high pressure to biological macromolecules can be used to find new structural states with a smaller specific volume of the system. High pressure NMR spectroscopy is a most promising analytical tool for the study of these states at atomic resolution. High pressure quartz cells are difficult to handle, high quality sapphire high pressure cells are difficult to obtain

Markus Beck Erlach; Claudia E. Munte; Werner Kremer; Rainer Hartl; Dörte Rochelt; Dieter Niesner; Hans Robert Kalbitzer

2010-01-01

377

Predicting Peptide Structures Using NMR Data and Deterministic  

E-print Network

Predicting Peptide Structures Using NMR Data and Deterministic Global Optimization J. L. KLEPEIS,1 energy structures of peptides modeled by full atom force Correspondence to: C. A. Floudas; e-8651 / 99 / 131354-17 #12;PREDICTING PEPTIDE STRUCTURES fields. Finally, the approach is applied

Neumaier, Arnold

378

X-ray CT and NMR imaging of rocks  

SciTech Connect

In little more than a decade, X-ray computerized tomography (CT) and nuclear magnetic resonance (NMR) imaging have become the premier modalities of medical radiology. Both of these imaging techniques also promise to be useful tools in petrophysics and reservoir engineering, because CT and NMR can nondestructively image a host of physical and chemical properties of porous rocks and multiple fluid phases contained within their pores. The images are taken within seconds to minutes, at reservoir temperatures and pressures, with spatial resolution on the millimeter and submillimeter level. The physical properties imaged by the two techniques are complementary. CT images bulk density and effective atomic number. NMR images the nuclide concentration, M/sub 0/, of a variety of nuclei (/sup 1/H, /sup 19/F, /sup 23/Na, /sup 31/P, etc.), their longitudinal and transverse relaxation-time curves (t/sub 1/ and t/sub 2/), and their chemical shift spectra. In rocks, CT images both rock matrix and pore fluids, while NMR images only mobile fluids and the interactions of these mobile fluids with the confining surfaces of the pores.

Vinegar, H.J.

1986-03-01

379

Saline absorption in calcium silicate brick observed by NMR scanning  

E-print Network

Saline absorption in calcium silicate brick observed by NMR scanning L. Pel #3; , K. Kopinga #3 in calcium-silicate brick was investigated by nuclear magnetic resonance scanning. This method hasCl solution in a calcium silicate brick will be discussed. 2 Theory If gravity is neglected, the isothermal

Eindhoven, Technische Universiteit

380

Nondestructive NMR technique for moisture determination in radioactive materials.  

SciTech Connect

This progress report focuses on experimental and computational studies used to evaluate nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) for detecting, quantifying, and monitoring hydrogen and other magnetically active nuclei ({sup 3}H, {sup 3}He, {sup 239}Pu, {sup 241}Pu) in Spent nuclear fuels and packaging materials. The detection of moisture by using a toroid cavity NMR imager has been demonstrated in SiO{sub 2} and UO{sub 2} systems. The total moisture was quantified by means of {sup 1}H NMR detection of H{sub 2}O with a sensitivity of 100 ppm. In addition, an MRI technique that was used to determine the moisture distribution also enabled investigators to discriminate between bulk and stationary water sorbed on the particles. This imaging feature is unavailable in any other nondestructive assay (NDA) technique. Following the initial success of this program, the NMR detector volume was scaled up from the original design by a factor of 2000. The capacity of this detector exceeds the size specified by DOE-STD-3013-96.

Aumeier, S.; Gerald, R.E. II; Growney, E.; Nunez, L.; Kaminski, M.

1998-12-04

381

Quantification of phospholipids in excised tissues by NMR  

SciTech Connect

A fraction of the total phospholipids is visible in natural abundance /sup 13/C NMR spectra of diseased human muscle biopsies which have been extracted with isopentane to remove neutral fats. The authors have quantified the visible phospholipids by inserting into the muscle biopsies a dioxane capillary which was calibrated against phospholipid vesicles (with known phosphate concentration) prepared from rat muscle and liver, and against pure palmitic and linolenic acid. The phospholipid content of the human muscles was calculated from the integrated peak area of the dioxane capillary, from the area of the 30.5 and 128.5 ppm peaks in the /sup 13/C spectrum of the muscle, and from the dry weight of the muscle, determined on the same sample which was used for /sup 13/C spectroscopy. The same experiments were carried out with rat muscle, brain, liver, and kidney. Furthermore, after the /sup 13/C spectrum of the tissue was recorded excess halothane was added into the NMR tube, the sample incubated, then the /sup 13/C spectrum re-recorded for quantification of the total phospholipids. Thus, their procedure quantitates both the NMR visible and the total phospholipids of the tissue. The total phospholipid content determined by NMR was in good agreement with that determined by chemical analysis.

Barany, M.; Venkatasubramanian, P.N.

1986-05-01

382

NMR Studies of Biomass and its Reaction Products  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biomass refers to biological material derived from living or recently living organisms, such as wood, agricultural products and wastes, and alcohol fuels. An increasingly popular R&D approach is to convert biomass into industrial polymers or chemicals. NMR is an excellent technique for the character...

383

Applications of 1H-NMR to Biodiesel Research  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biodiesel is an alternative diesel fuel derived from vegetable oils, animal fats, or used cooking oils. It is produced by reacting these materials with an alcohol in the presence of a catalyst to give the corresponding mono-alkyl esters. 1H-NMR is a routine analytical method that has been used for...

384

Proton NMR characterization of a hydrophobic treatment of pore surfaces  

Microsoft Academic Search

We propose proton NMR and longitudinal relaxation experiments to study the structure and dynamics of water within calibrated hydrophobic mesoporous silica samples. We show the relevance of these methods to qualify the hydrophobic treatment for a water–substrate combination corresponding to a non-wetting situation.

Dominique Petit; Jean-Pierre Korb

2001-01-01

385

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

PubMed

Nuclear magnetic resonance (NMR) is arguably the most direct methodology for characterizing the higher-order structure of proteins in solution. Structural characterization of proteins by NMR typically utilizes heteronuclear experiments. However, for formulated monoclonal antibody (mAb) therapeutics, the use of these approaches is not currently tenable due to the requirements of isotope labeling, the large size of the proteins, and the restraints imposed by various formulations. Here, we present a new strategy to characterize formulated mAbs using (1)H NMR. This method, based on the pulsed field gradient stimulated echo (PGSTE) experiment, facilitates the use of (1)H NMR to generate highly resolved spectra of intact mAbs in their formulation buffers. This method of data acquisition, along with postacquisition signal processing, allows the generation of structural and hydrodynamic profiles of antibodies. We demonstrate how variation of the PGSTE pulse sequence parameters allows proton relaxation rates and relative diffusion coefficients to be obtained in a simple fashion. This new methodology can be used as a robust way to compare and characterize mAb therapeutics. PMID:24006877

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

2013-10-15

386

ORIGINAL PAPER NMR spectroscopy as a screening tool to validate  

E-print Network

of food surveillance to validate the "lactose-free" claims labeled on these beverages. Using softORIGINAL PAPER NMR spectroscopy as a screening tool to validate nutrition labeling of milk, lactose. Furthermore, quantitative data regarding nutrition labeling parameters were predicted from the same spectra

Paris-Sud XI, Université de

387

An NMR Protonation Study of Metal Diethylenetriaminepentaacetic Acid Complexes.  

ERIC Educational Resources Information Center

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

Letkeman, Peter

1979-01-01

388

Ultralow-field NMR on Room Temperature samples  

E-print Network

-Field Magnetic Resonance Imaging (LF-MRI). Finally, preliminary work on the design of the follow-up SQUID NMR) systems based on Superconducting QUantum Interference Device (SQUID) detection for use on room temperature control, two-component free induc- tion decays were obtained from oil-water mixtures at temperatures

Sheldon, Nathan D.

389

Noise reduction for NMR FID signals via Gabor expansion  

Microsoft Academic Search

The parameters in a nuclear magnetic resonance (NMR) free induction decay (FID) signal contain information that is useful in biological and biomedical applications and research. A real time-sampled FID signal is well modeled as a finite mixture of modulated exponential sequences plus noise. The authors propose to use the generalized Gabor expansion for noise reduction, where the generalized Gabor expansion

Youhong Lu; Sanjay Joshi; Joel M. Morris

1997-01-01

390

Advancements in waste water characterization through NMR spectroscopy: review.  

PubMed

There are numerous organic pollutants that lead to several types of ecosystem damage and threaten human health. Wastewater treatment plants are responsible for the removal of natural and anthropogenic pollutants from the sewage, and because of this function, they play an important role in the protection of human health and the environment. Nuclear magnetic resonance (NMR) has proven to be a valuable analytical tool as a result of its versatility in characterizing both overall chemical composition as well as individual species in a wide range of mixtures. In addition, NMR can provide physical information (rigidity, dynamics, etc.) as well as permit in depth quantification. Hyphenation with other techniques such as liquid chromatography, solid phase extraction and mass spectrometry creates unprecedented capabilities for the identification of novel and unknown chemical species. Thus, NMR is widely used in the study of different components of wastewater, such as complex organic matter (fulvic and humic acids), sludge and wastewater. This review article summarizes the NMR spectroscopy methods applied in studies of organic pollutants from wastewater to provide an exhaustive review of the literature as well as a guide for readers interested in this topic. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25280056

Alves Filho, Elenilson G; Alexandre E Silva, Lorena M; Ferreira, Antonio G

2014-10-01

391

On-line system for NMR polarization measurement  

Microsoft Academic Search

The on-line system of the SMC polarized target with emphasis on the NMR polarization measurement system is presented. Target subsystems are controlled or monitored by local processors and a host ?-VAX computer which collects all data and provides the user interface. The Global Section scheme is used as a common data block and achieves the synchronization between subsystems. The communication

N. Hayashi; M. Boutemeur; S. Bültmann; D. Crabb; D. Day; S. Dhawan; C. Dulya; E. Gülmez; T. Hasegawa; N. Horikawa; S. Ishimoto; T. Iwata; A. Kishi; L. Klostermann; D. Krämer; J. M. Le Goff; A. Magnon; T. O. Niinikoski; A. Rijllart; W. Thiel; S. Trentalange

1995-01-01

392

MULTIVARIATE CURVE RESOLUTION OF NMR SPECTROSCOPY METABONOMIC DATA  

EPA Science Inventory

Sandia National Laboratories is working with the EPA to evaluate and develop mathematical tools for analysis of the collected NMR spectroscopy data. Initially, we have focused on the use of Multivariate Curve Resolution (MCR) also known as molecular factor analysis (MFA), a tech...

393

Discovering High-Affinity Ligands for Proteins: SAR by NMR  

NSDL National Science Digital Library

A nuclear magnetic resonance (NMR)-based method is described in which small organic molecules that bind to proximal subsites of a protein are identified, optimized, and linked together to produce high-affinity ligands. The method reduces the amount of chemical synthesis and time required for the discovery of high-affinity ligands and appears particularly useful in target-directed drug research.

Suzanne B. Shuker (Abbott Laboratories; )

1996-11-29

394

Solid-State NMR Spectroscopy for the Physical Chemistry Laboratory  

ERIC Educational Resources Information Center

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

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

2013-01-01

395

MVAPACK: A Complete Data Handling Package for NMR Metabolomics  

E-print Network

MVAPACK: A Complete Data Handling Package for NMR Metabolomics Bradley Worley and Robert Powers of metabolomics experiments are forced to either purchase expensive software packages or craft their own data contributed to the rapid growth of the field. Unfortunately, commercial software packages available

Powers, Robert

396

Xenon NMR of phase biaxiality in liquid crystals.  

PubMed

Biaxial thermotropic nematic liquid crystals would be of great importance in liquid crystal display technology. Less than a decade ago, such liquid crystals were suggested. The biaxiality of the phases was confirmed using (2)H NMR spectroscopy of deuterated probe molecules. The spectra were collected from a sample rotating around an axis perpendicular to the external magnetic field, resulting in a two-dimensional powder pattern. We have proposed an alternate technique that is based on the second order quadrupole shift detectable in (131)Xe NMR spectra of dissolved xenon. The method has many advantages, such as the NMR spectra are taken from a static sample and the (131)Xe quadrupole coupling tensor is extremely sensitive to the symmetry of the phase. In the present study, we report results obtained on a 600-MHz NMR spectrometer. Together with the data of our earlier study, they confirm that the asymmetry parameter of the (131)Xe quadrupole coupling tensor in the nematic phase of a ferroelectric liquid crystal is 0.85 and in the smectic A phase ca 0.62, indicating significant phase biaxiality. PMID:24771455

Jokisaari, Jukka; Zhu, Jianfeng

2014-10-01

397

Extended hopane derivatives in sediments - Identification by H-1 NMR  

NASA Technical Reports Server (NTRS)

Sedimentary C32 hopanoic acid, one of the most abundant in nature and of probable bacterial origin, has been isolated for the first time as a single component and characterized by H-1 NMR. The 17 alpha H, 21 beta H configuration of the C31 alkane has been similarly confirmed.

Taylor, J.; Wardroper, A. M. K.; Maxwell, J. R.

1980-01-01

398

Single bead detection with an NMR microcapillary probe  

NASA Astrophysics Data System (ADS)

We have developed a nuclear magnetic resonance (NMR) microcapillary probe for the detection of single magnetic microbeads. The geometry of the probe has been optimized so that the signal from the background water has a similar magnitude compared to the signal from the dephased water nearby a single magnetic bead within the probe detector coil. In addition, the RF field of the coil must be uniform within the effective range of the magnetic bead. Three different RF probes were tested in a 7 T (300 MHz) pulsed NMR spectrometer with sample volumes ranging from 5 nL down to 1 nL. The 1 nL probe had a single-shot signal-to-noise ratio (SNR) for pure water of 27 and a volume resolution that exhibits a 600-fold improvement over a conventional (5 mm tube) NMR probe with a sample volume of 18 ?L. This allowed for the detection of a 1 ?m magnetite/polystyrene bead (m = 2 × 10-14 A m2) with an estimated experimental SNR of 30. Simulations of the NMR spectra for the different coil geometries and positions of the bead within the coil were developed that include the B0 shift near a single bead, the inhomogeneity of the coils, the local coil sensitivity, the skin effect of the coil conductor, and quantitated estimates of the proximity effect between coil windings.

Nakashima, Yoshihiro; Boss, Michael; Russek, Stephen E.; Moreland, John

2012-11-01

399

Structural determination of diterpenes from Daphne genkwa by NMR spectroscopy.  

PubMed

Five daphnane type diterpenes have been isolated from the chloroform soluble fraction of Daphne genkwa. The structure of the new compound (1) was assigned as 5beta-hydroxyresiniferonol-6alpha,7alpha-epoxy-12beta-acetoxy-9,13,14-ortho-2E-decenoate by extensive NMR studies. PMID:16953522

Akhtar, Kalsoom; Khan, Sher Bahadar; Ali, Irshad

2006-11-01

400

Relative Configuration of Natural Products Using NMR Chemical Shifts  

Technology Transfer Automated Retrieval System (TEKTRAN)

By comparing calculated with experimental NMR chemical shifts, we were able to determine the relative configurations of three monoterpene diastereomers produced by the walkingstick Anisomorpha buprestoides. The combined RMSDs of both 1H and 13C quantum chemically calculated shifts were able to predi...

401

Journal of Biomolecular NMR, 26: 281282, 2003. KLUWER/ESCOM  

E-print Network

: assignment, chromophore, GFP, NMR Biological context The green fluorescent protein (GFP) from the jelly- fish Fluorescent Protein (GFP) Farid Khana, Katherine Stottb & Sophie Jacksona aUniversity of Cambridge, Centre for Protein Engineering, Department of Chemistry, Lensfield Road, Cambridge, CB2 1EW, U.K.; bCambridge Centre

Jackson, Sophie

402

Quantum Information Processing with NMR MIT Department of Physics  

E-print Network

Quantum Information Processing with NMR MIT Department of Physics (Dated: August 26, 2010) This experiment will let you perform a series of simple quantum computations on a two spin system, demonstrating one and two quantum-bit quantum logic gates, and a circuit implementing the Deutsch-Jozsa quantum

Seager, Sara

403

INTRODUCTION TO NMR AND ITS APPLICATION IN METABOLITE  

E-print Network

of metabolism cannot be readily assigned by other techniques. Drug Metabolism in Drug Design and Development 1982), and (v) ligand binding screening for drug discovery (Hajduk, 2006; Lepre et al., 2004; Orry et al., 2006; Zartler et al. 2006). In the field of drug metabolism (Corcoran and Spraul, 2003), NMR

Powers, Robert

404

Multi-planar image formation using NMR spin echoes  

Microsoft Academic Search

A new method of two- or three-dimensional spin density imaging by nuclear magnetic resonance (NMR) is proposed, which exploits the properties of spin echoes in time- dependent magnetic field gradients. An analysis shows that simultaneous observation and differentiation of signals, arising from all spins distributed in a plane or set of planes within the specimen, is possible. The method is

P. Mansfield

1977-01-01

405

ECG gated NMR-CT for cardiovascular diseases  

SciTech Connect

The authors have been applying ECG gated NMR-CT to mainly patients with myocardial infarction (MI), and hypertrophic cardiomyopathy (HCM). Thirteen patients with MI, 8 with HCM and 5 without any heart diseases were studied by ECG gated NMR imaging (spin-echo technique, TR: depends on patient heart rate, TE: 35 and 70 msec.) with 0.35 T superconducting magnet. On NMR images (MRI), the authors examined the wall thickness, wall motion and T/sub 2/ relaxation time in the area of diseased myocardium. The lesions of old MI were depicted as the area of thin wall and T/sub 2/ relaxation time of those lesions were similar to the area of non-infarcted myocardium. The lesions of recent MI (up to 3.5 months from the recent attack) were shown as the same wall thickness as the non-infarcted myocardium and the area of prolonged T/sub 2/ relaxation time compared with that of non-infarcted myocardium. MRI demonstrated diffusely thick myocardium in all patients with HCM. T/sub 2/ relaxation time of the areas of HCM was almost the same as that of normal myocardium, and it's difference among each ventricular wall in patients with HCM was not statistically significant. The authors conclude that ECG gated NMR-CT offers 3-D morphological information of the heart without any contrast material nor radioisotopes. ECG gated MRI provides the useful informations to diagnose MI, especially in the differential diagnosis between old and recent MI.

Nishikawa, J.; Ohtake, T.; Machida, K.; Iio, M.; Yoshimoto, N.; Sugimoto, T.

1985-05-01

406

Cation Hydration Constants by Proton NMR: A Physical Chemistry Experiment.  

ERIC Educational Resources Information Center

Studies the polarization effect on water by cations and anions. Describes an experiment to illustrate the polarization effect of sodium, lithium, calcium, and strontium ions on the water molecule in the hydration spheres of the ions. Analysis is performed by proton NMR. (MVL)

Smith, Robert L.; And Others

1988-01-01

407

SPECTROSCOPIC STUDIES (EPR, NMR) APPLICATIONS OF MAGNETICALLY COUPLED  

E-print Network

, which binds to the laminin receptor on endothelial cells and inhibits metastatic tumor invasion.S. Taylor, J. Murphy- Boesch, D.B. Vigneron, Dept. ofNMR and Medical Spectroscopy, Fox Chase Cancer Center). Biological control and/or adhesion systems often depend on interactions between proteins that cannot

Asher, Sanford A.

408

An NMR Chemometrics Toolbox for GNU Octave Bradley Worley  

E-print Network

MVAPACK An NMR Chemometrics Toolbox for GNU Octave Bradley Worley #12;1 This manual is for the MVAPACK toolbox for GNU Octave. Copyright c 2014 University of Nebraska Board of Regents. MATLAB R by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being "The MVAPACK

Powers, Robert

409

Multinuclear NMR study of silica fiberglass modified with zirconia.  

PubMed

Silica fiberglass textiles are emerging as uniquely suited supports in catalysis, which offer unprecedented flexibility in designing advanced catalytic systems for chemical and auto industries. During manufacturing fiberglass materials are often modified with additives of various nature to improve glass properties. Glass network formers, such as zirconia and alumina, are known to provide the glass fibers with higher strength and to slow down undesirable devitrification processes. In this work multinuclear (1)H, (23)Na, (29)Si, and (91)Zr NMR spectroscopy was used to characterize the effect of zirconia on the molecular-level fiberglass structure. (29)Si NMR results help in understanding why zirconia-modified fiberglass is more stable towards devitrification comparing with pure silica glass. Internal void spaces formed in zirconia-silica glass fibers after acidic leaching correlate with sodium and water distributions in the starting bulk glass as probed by (23)Na and (1)H NMR. These voids spaces are important for stabilization of catalytically active species in the supported catalysts. Potentials of high-field (91)Zr NMR spectroscopy to study zirconia-containing glasses and similarly disordered systems are illustrated. PMID:21277754

Lapina, O B; Khabibulin, D F; Terskikh, V V

2011-01-01

410

Pulsed zero field NMR of solids and liquid crystals  

SciTech Connect

This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs.

Thayer, A.M.

1987-02-01

411

Xenon NMR measurements of permeability and tortuosity in reservoir rocks  

E-print Network

Xenon NMR measurements of permeability and tortuosity in reservoir rocks Ruopeng Wanga,b , Tina of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number

Walsworth, Ronald L.

412

[NMR-relaxometry in the serum of hematologic patients].  

PubMed

The time of NMR-spin-lattice relaxation of 65 serum samples from acute leukemia patients and those with chronic myelo- and lymphoproliferative diseases was measured. The patients studied demonstrated greater values of the parameter which proved dissimilar at various stages of the disease in the same patients. PMID:8188022

Tsyba, N N; Popova, O V; Gangardt, M G; Kozinets, G I

1994-01-01

413

Field Experiment Provides Ground Truth for Surface NMR Measurement  

NASA Astrophysics Data System (ADS)

Effective and sustainable long-term management of fresh water resources requires accurate information about the availability of water in groundwater aquifers. Proton Nuclear Magnetic Resonance (NMR) can provide a direct link to the presence of water in the pore space of geological materials through the detection of the nuclear magnetization of the hydrogen nuclei (protons) in the pore water. Of interest for groundwater applications is the measurement of the proton-NMR relaxation time constant, referred to as T2. This parameter is sensitive to the geometry of the water-filled pore space and can be related to the hydraulic conductivity. NMR logging instruments, which have been available since the 1980’s, provide direct measurements of T2 in boreholes. Surface NMR (SNMR) is a non-invasive geophysical method that uses a loop of wire on the surface to probe the NMR properties of groundwater aquifers to a depth of ~100 m, without the need for the drilling of boreholes. SNMR provides reliable measurements of a different NMR time constant referred to as T2*, that is related to, but not necessarily equivalent to, T2. The relationship between T2* and T2 is likely to depend upon the physical environment and the composition of the sampled material. In order to advance the use of SNMR as a non-invasive means of characterizing groundwater aquifers, we must answer the fundamental question: When probing a groundwater aquifer, what information is provided by T2*, the time constant measured with SNMR? Our approach was to conduct a field experiment in Nebraska, in an area underlain by the Quaternary Alluvium and Tertiary Ogallala aquifers. We first used SNMR to obtain a 1D profile of T2* to a depth of ~60 m. We then drilled a well inside the area of the SNMR loop, to a depth of ~150 m, and used the drill cuttings to describe the composition of the geologic material at the site. The borehole was kept open for 2 days to acquire logging NMR T2 measurements over the total depth. Three months later, borehole NMR T2 measurements were repeated with a second instrument; and logging measurements were made of the ambient magnetic field. Comparison of the three measurements of NMR relaxation show that T2* at this site is affected by inhomogeneity in the background magnetic field; this effect is most pronounced in sand and gravel units where dephasing, rather than surface relaxation, dominates the NMR response. When the borehole T2 measurements are transformed to T2*, by incorporating a term to account for this effect, we find good agreement between the two forms of measurement over the investigated depth range. The ability to ground truth the SNMR measurement has advanced our understanding of the time constant measured by SNMR, T2*, and its relationship to pore-scale properties. This is a critical step in developing SNMR as a reliable geophysical method for evaluation of groundwater resources.

Knight, R. J.; Abraham, J. D.; Cannia, J. C.; Dlubac, K. I.; Grau, B.; Grunewald, E. D.; Irons, T.; Song, Y.; Walsh, D.

2010-12-01

414

Study of correlations in molecular motion by multiple quantum NMR  

SciTech Connect

Nuclear magnetic resonance is a very useful tool for characterizing molecular configurations through the measurement of transition frequencies and dipolar couplings. The measurement of spectral lineshapes, spin-lattice relaxation times, and transverse relaxation times also provide us with valuable information about correlations in molecular motion. The new technique of multiple quantum nuclear magnetic resonance has numerous advantages over the conventional single quantum NMR techniques in obtaining information about static and dynamic interactions of coupled spin systems. In the first two chapters, the theoretical background of spin Hamiltonians and the density matrix formalism of multiple quantum NMR is discussed. The creation and detection of multiple quantum coherence by multiple pulse sequence are discussed. Prototype multiple quantum spectra of oriented benzene are presented. Redfield relaxation theory and the application of multiple quantum NMR to the study of correlations in fluctuations are presented. A specific example of an oriented methyl group relaxed by paramagnetic impurities is studied in detail. The study of possible correlated motion between two coupled methyl groups by multiple quantum NMR is presented. For a six spin system it is shown that the four-quantum spectrum is sensitive to two-body correlations, and serves a ready test of correlated motion. The study of the spin-lattice dynamics of orienting or tunneling methyl groups (CH/sub 3/ and CD/sub 3/) at low temperatures is presented. The anisotropic spin-lattice relaxation of deuterated hexamethylbenzene, caused by the sixfold reorientation of the molecules, is investigated, and the NMR spectrometers and other experimental details are discussed.

Tang, J.H.

1981-11-01

415

NMR metabolomics for assessment of exercise effects with mouse biofluids.  

PubMed

Exercise modulates the metabolome in urine or blood as demonstrated previously for humans and animal models. Using nuclear magnetic resonance (NMR) metabolomics, the present study compares the metabolic consequences of an exhaustive exercise at peak velocity (Vp) and at critical velocity (Vc) on mice. Since small-volume samples (blood and urine) were collected, dilution was necessary to acquire NMR spectra. Consequently, specific processing methods were applied before statistical analysis. According to the type of exercise (control group, Vp group and Vc group), 26 male mice were divided into three groups. Mice were sacrificed 2 h after the end of exercise, and urine and blood samples were drawn from each mouse. Proton NMR spectra were acquired with urine and deproteinized blood. The NMR data were aligned with the icoshift method and normalised using the probabilistic quotient method. Finally, data were analysed with the orthogonal projection of latent-structure analysis. The spectra obtained with deproteinized blood can neither discriminate the control mice from exercised mice nor discriminate according to the duration of the exercise. With urine samples, a significant statistical model can be estimated when comparing the control mice to both groups, Vc and Vp. The best model is obtained according to the exercise duration with all mice. Taking into account the spectral regions having the highest correlations, the discriminant metabolites are allantoin, inosine and branched-chain amino acids. In conclusion, metabolomic profiles assessed with NMR are highly dependent on the exercise. These results show that urine samples are more informative than blood samples and that the duration of the exercise is a more important parameter to influence the metabolomic status than the exercise velocity. PMID:22706325

Le Moyec, Laurence; Mille-Hamard, Laurence; Triba, Mohamed N; Breuneval, Carole; Petot, Hélène; Billat, Véronique L

2012-08-01

416

SPE-NMR metabolite sub-profiling of urine.  

PubMed

NMR-based metabolite profiling of urine is a fast and reproducible method for detection of numerous metabolites with diverse chemical properties. However, signal overlap in the (1)H NMR profiles of human urine may hamper quantification and identification of metabolites. Therefore, a new method has been developed using automated solid-phase extraction (SPE) combined with NMR metabolite profiling. SPE-NMR of urine resulted in three fractions with complementary and reproducible sub-profiles. The sub-profile from the wash fraction (100 % water) contained polar metabolites; that from the first eluted fraction (10 % methanol-90 % water) semi-polar metabolites; and that from the second eluted fraction (100 % methanol) aromatic metabolites. The method was validated by analysis of urine samples collected from a crossover human nutritional intervention trial in which healthy volunteers consumed capsules containing a polyphenol-rich mixture of red wine and grape juice extract (WGM), the same polyphenol mixture dissolved in a soy drink (WGM_Soy), or a placebo (PLA), over a period of five days. Consumption of WGM clearly increased urinary excretion of 4-hydroxyhippuric acid, hippuric acid, 3-hydroxyphenylacetic acid, homovanillic acid, and 3-(3-hydroxyphenyl)-3-hydroxypropionic acid. However, there was no difference between the excreted amounts of these metabolites after consumption of WGM or WGM_Soy, indicating that the soy drink is a suitable carrier for WGM polyphenols. Interestingly, WGM_Soy induced a significant increase in excretion of cis-aconitate compared with WGM and PLA, suggesting a higher demand on the tricarboxylic acid cycle. In conclusion, SPE-NMR metabolite sub-profiling is a reliable and improved method for quantification and identification of metabolites in urine to discover dietary effects and markers of phytochemical exposure. PMID:22932811

Jacobs, Doris M; Spiesser, Laura; Garnier, Maxime; de Roo, Niels; van Dorsten, Ferdi; Hollebrands, Boudewijn; van Velzen, Ewoud; Draijer, Richard; van Duynhoven, John

2012-11-01

417

Deducing relative permeability of tight gas rocks from NMR measurements  

NASA Astrophysics Data System (ADS)

As the economic production of hydrocarbons from unconventional sources, such as tight gas, is getting more and more important, understanding the differences in petrophysical behavior compared to conventional fields is crucial. The prediction of key reservoir parameters in low-permeability gas systems therefore needs new approaches in laboratory methods. Our research aims at predicting transport and storage properties such as gas/water content and relative permeability on based Nuclear Magnetic Resonance (NMR) measurements. NMR (at full water saturation) is sensitive to porosity and pore size distribution. Thus the method is commonly used to estimate the absolute permeability of rocks. At partial saturation the conventional capillary pore models used for NMR interpretation fail to predict the water distribution in the pore system because they do not account for the water trapped in corners or attached to the inner surface as a wetting film. Therefore, they shouldn't be applied for relative permeability calculation. We used a bundle of capillaries with equilateral triangle-cross-sections to simulate water distribution and transport both for drainage and imbibition as well as the corresponding NMR relaxometry responses. The triangular pore shape was chosen because of the tri- and multi-angular shaped pores caused by secondary clay growth in the pores and observed by SEM (scanning electron microscopy). In contrast to the commonly used tubular pore models this alternative approach accounts for residual water e.g. in corner meniscii. For model validation we used pore throat size distributions obtained from mercury porosimetry as well as from SEM images to calculate both NMR response and permeability. The calculated results correlate well with laboratory measurements carried out on tight gas rocks.

Jorand, R.; Klitzsch, N.; Mohnke, O.; Clauser, C.; Schleifer, N.; de Wijn, B.

2011-12-01

418

Toxic actions of dinoseb in medaka ( Oryzias latipes) embryos as determined by in vivo 31P NMR, HPLC-UV and 1H NMR metabolomics  

Microsoft Academic Search

Changes in metabolism of Japanese medaka (Oryzias latipes) embryos exposed to dinoseb (2-sec-butyl-4,6-dinitrophenol), a substituted dinitrophenol herbicide, were determined by in vivo 31P NMR, high-pressure liquid chromatography (HPLC)-UV, and 1H NMR metabolomics. ATP and phosphocreatine (PCr) metabolism were characterized within intact embryos by in vivo 31P NMR; concentrations of ATP, GTP, ADP, GDP, AMP and PCr were determined by HPLC-UV;

Mark R. Viant; Christopher A. Pincetich; David E. Hinton; Ronald S. Tjeerdema

2006-01-01

419

NightShift: NMR shift inference by general hybrid model training - a framework for NMR chemical shift prediction  

PubMed Central

Background NMR chemical shift prediction plays an important role in various applications in computational biology. Among others, structure determination, structure optimization, and the scoring of docking results can profit from efficient and accurate chemical shift estimation from a three-dimensional model. A variety of NMR chemical shift prediction approaches have been presented in the past, but nearly all of these rely on laborious manual data set preparation and the training itself is not automatized, making retraining the model, e.g., if new data is made available, or testing new models a time-consuming manual chore. Results In this work, we present the framework NightShift (NMR Shift Inference by General Hybrid Model Training), which enables automated data set generation as well as model training and evaluation of protein NMR chemical shift prediction. In addition to this main result – the NightShift framework itself – we describe the resulting, automatically generated, data set and, as a proof-of-concept, a random forest model called Spinster that was built using the pipeline. Conclusion By demonstrating that the performance of the automatically generated predictors is at least en par with the state of the art, we conclude that automated data set and predictor generation is well-suited for the design of NMR chemical shift estimators. The framework can be downloaded from https://bitbucket.org/akdehof/nightshift. It requires the open source Biochemical Algorithms Library (BALL), and is available under the conditions of the GNU Lesser General Public License (LGPL). We additionally offer a browser-based user interface to our NightShift instance employing the Galaxy framework via https://ballaxy.bioinf.uni-sb.de/. PMID:23496927

2013-01-01

420

Bioagent detection using miniaturized NMR and nanoparticle amplification : final LDRD report.  

SciTech Connect

This LDRD program was directed towards the development of a portable micro-nuclear magnetic resonance ({micro}-NMR) spectrometer for the detection of bioagents via induced amplification of solvent relaxation based on superparamagnetic nanoparticles. The first component of this research was the fabrication and testing of two different micro-coil ({micro}-coil) platforms: namely a planar spiral NMR {micro}-coil and a cylindrical solenoid NMR {micro}-coil. These fabrication techniques are described along with the testing of the NMR performance for the individual coils. The NMR relaxivity for a series of water soluble FeMn oxide nanoparticles was also determined to explore the influence of the nanoparticle size on the observed NMR relaxation properties. In addition, The use of commercially produced superparamagnetic iron oxide nanoparticles (SPIONs) for amplification via NMR based relaxation mechanisms was also demonstrated, with the lower detection limit in number of SPIONs per nanoliter (nL) being determined.

Clewett, C. F. M.; Adams, David Price; Fan, Hongyou; Williams, John D.; Sillerud, Laurel O.; Alam, Todd Michael; Aldophi, Natalie L. (New Mexico Resonance, Albuquerque, NM); McDowell, Andrew F. (New Mexico Resonance, Albuquerque, NM)

2006-11-01

421

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

SciTech Connect

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

Alam, Todd Michael; McIntyre, Sarah K.

2011-05-01

422

Proton NMR studies of functionalized nanoparticles in aqueous environments  

NASA Astrophysics Data System (ADS)

Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results in high-resolution NMR spectra. This technique is selective for protons on the surface organic functional groups due to their motional averaging in solution. In this study, 1H solution NMR spectroscopy was used to investigate the interface of the organic functional groups in D2O. The pKa for these functional groups covalently bound to the surface of nanoparticles was determined using an NMR-pH titration method based on the variation in the proton chemical shift for the alkyl group protons closest to the amine group with pH. The adsorption of toxic contaminants (chromate and arsenate anions) on the surface of functionalized silicalite-1 and mesoporous silica nanoparticles has been studied by 1H solution NMR spectroscopy. With this method, the surface bound contaminants are detected. The analysis of the intensity and position of these peaks allows quantitative assessment of the relative amounts of functional groups with adsorbed metal ions. These results demonstrate the sensitivity of solution NMR spectroscopy to the electronic environment and structure of the surface functional groups on porous nanomaterials.

Tataurova, Yulia Nikolaevna

423

Deriving NMR surface relaxivities, pore size distributions and water retention curves by NMR relaxation experiments on partially de-saturated rocks  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) is a method used over a wide field of geophysical applications to non-destructively determine transport and storage properties of rocks and soils. In NMR relaxometry signal amplitudes correspond directly to the rock's fluid (water, oil) content. On the other hand the NMR relaxation behavior, i.e. the longitudinal (T1) and transverse (T2) NMR relaxation times, can be used to derive pore sizes and permeability as it is linearly linked to the pore's surface-to-volume-ratio and physiochemical properties of the rock-fluid interface by the surface relaxivity ?_s This parameter, however, is dependent on the type and mineral constituents of the investigated rock sample and thus has to be determined and calibrated prior to estimating pore sizes from NMR relaxometry measurements. Frequently used methods to derive surface relaxivity to calibrate NMR pore sizes comprise mercury injection, pulsed field gradients (PFG-NMR) or grain size analysis. This study introduces an alternative approach to jointly estimate NMR surface relaxivity and pore radii distributions using NMR relaxation data obtained from partially de-saturated rocks. In this, inverse modeling is carried on a linked Young Laplace equation for capillary bundles and the Brownstein and Tarr equations. Subsequently, this approach is used to predict water retention curves of the investigated rocks. The method was tested and validated on simulated and laboratory transverse NMR data. Calculated inverse models are generally in a good agreement with results obtained from mercury injection and drainage measurements. Left: Measured and predicted water retention (pF) curves. Center: NMR relaxometry data, fit and error. Right: Mercury injection data (HgPor, dashed line) and jointly derived pore radii distributions and surface relaxivity by joint inverse modelling

Mohnke, O.; Nordlund, C. L.; Klitzsch, N.

2013-12-01

424

Molecular structure by two-dimensional NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Two examples are presented of the use of two-dimensional NMR spectroscopy to solve molecular structure problems. The first is called correlation spectroscopy (COSY) and it allows us to disentangle a complex network of spin-spin couplings. By dispersing the NMR information in two frequency dimensions, it facilitates the analysis of very complex spectra of organic and biochemical molecules, normally too crowded to be tractable. The second application exploits the special properties of multiple-quantum coherence to explore the molecular framework one C?C linkage at a time. The natural product panamine is used as a test example; with some supplementary evidence, the structure of this six-ringed heterocyclic molecule is elucidated from the double-quantum filtered two-dimensional spectrum.

Freeman, R.

425

NMR apparatus for in situ analysis of fuel cells  

DOEpatents

The subject apparatus is a fuel cell toroid cavity detector for in situ analysis of samples through the use of nuclear magnetic resonance. The toroid cavity detector comprises a gas-tight housing forming a toroid cavity where the housing is exposed to an externally applied magnetic field B.sub.0 and contains fuel cell component samples to be analyzed. An NMR spectrometer is electrically coupled and applies a radiofrequency excitation signal pulse to the detector to produce a radiofrequency magnetic field B.sub.1 in the samples and in the toroid cavity. Embedded coils modulate the static external magnetic field to provide a means for spatial selection of the recorded NMR signals.

Gerald, II, Rex E; Rathke, Jerome W

2012-11-13

426

Field-swept 33S NMR study of elemental sulfur  

NASA Astrophysics Data System (ADS)

Field-swept 33S NMR spectra of a cyclic octaatomic molecule of elemental sulfur, ?-S8, are presented. The spectra were acquired at a Larmor frequency of 16.2 MHz and using a superconducting magnet at between 6.32 and 0.50 T. Methods were developed for analyzing the field-swept 33S NMR spectra in which both Zeeman and quadrupole interactions were dominant. The quadrupole coupling constant, CQ, and the asymmetry parameter, ?Q, for ?-S8 were found to be 43.68 MHz and 0.57, respectively. T1 measurements of ?-S8 were conducted using the nuclear quadrupole resonance signals, and the activation energy was determined to be 54(1) kJ mol-1 from these T1 measurements. The molecular motion was assigned to ring-puckering of ?-S8 molecules within the crystal structure.

Yamada, Kazuhiko; Kitagawa, Kentaro; Takahashi, Masato

2015-01-01

427

Susceptibility-matched plugs for microcoil NMR probes.  

PubMed

For mass-limited samples, the residual sample volume outside the detection coil is an important concern, as is good base line resolution. Here, we present the construction and evaluation of magnetic susceptibility-matched plugs for microcoil NMR sample cells which address these issues. Mixed-epoxy glue and ultem tube plugs that have susceptibility values close to those of perfluorocarbon FC-43 (fluorinert) and copper were used in small volume (0.5-2 microL) and larger volume (15-20 microL) thin glass capillary sample cells. Using these plugs, the sample volume efficiency (i.e. ratio of active volume to total sample volume in the microcoil NMR cell) was improved by 6-12-fold without sensitivity and resolution trade-offs. Comparison with laser etched or heat etched microcoil sample cells is provided. The approaches described are potentially useful in metabolomics for biomarkers detection in mass limited biological samples. PMID:20510638

Kc, Ravi; Gowda, Yashas N; Djukovic, Danijel; Henry, Ian D; Park, Gregory H J; Raftery, Daniel

2010-07-01

428

Double rotation NMR studies of zeolites and aluminophosphate molecular sieves  

SciTech Connect

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

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

1993-07-01

429

Characterizing RNA ensembles from NMR data with kinematic models.  

PubMed

Functional mechanisms of biomolecules often manifest themselves precisely in transient conformational substates. Researchers have long sought to structurally characterize dynamic processes in non-coding RNA, combining experimental data with computer algorithms. However, adequate exploration of conformational space for these highly dynamic molecules, starting from static crystal structures, remains challenging. Here, we report a new conformational sampling procedure, KGSrna, which can efficiently probe the native ensemble of RNA molecules in solution. We found that KGSrna ensembles accurately represent the conformational landscapes of 3D RNA encoded by NMR proton chemical shifts. KGSrna resolves motionally averaged NMR data into structural contributions; when coupled with residual dipolar coupling data, a KGSrna ensemble revealed a previously uncharacterized transient excited state of the HIV-1 trans-activation response element stem-loop. Ensemble-based interpretations of averaged data can aid in formulating and testing dynamic, motion-based hypotheses of functional mechanisms in RNAs with broad implications for RNA engineering and therapeutic intervention. PMID:25114056

Fonseca, Rasmus; Pachov, Dimitar V; Bernauer, Julie; van den Bedem, Henry

2014-09-01

430

Characterizing RNA ensembles from NMR data with kinematic models  

PubMed Central

Functional mechanisms of biomolecules often manifest themselves precisely in transient conformational substates. Researchers have long sought to structurally characterize dynamic processes in non-coding RNA, combining experimental data with computer algorithms. However, adequate exploration of conformational space for these highly dynamic molecules, starting from static crystal structures, remains challenging. Here, we report a new conformational sampling procedure, KGSrna, which can efficiently probe the native ensemble of RNA molecules in solution. We found that KGSrna ensembles accurately represent the conformational landscapes of 3D RNA encoded by NMR proton chemical shifts. KGSrna resolves motionally averaged NMR data into structural contributions; when coupled with residual dipolar coupling data, a KGSrna ensemble revealed a previously uncharacterized transient excited state of the HIV-1 trans-activation response element stem–loop. Ensemble-based interpretations of averaged data can aid in formulating and testing dynamic, motion-based hypotheses of functional mechanisms in RNAs with broad implications for RNA engineering and therapeutic intervention. PMID:25114056

Fonseca, Rasmus; Pachov, Dimitar V.; Bernauer, Julie; van den Bedem, Henry

2014-01-01

431

Susceptibility-matched plugs for microcoil NMR probes  

NASA Astrophysics Data System (ADS)

For mass-limited samples, the residual sample volume outside the detection coil is an important concern, as is good base line resolution. Here, we present the construction and evaluation of magnetic susceptibility-matched plugs for microcoil NMR sample cells which address these issues. Mixed-epoxy glue and ultem tube plugs that have susceptibility values close to those of perfluorocarbon FC-43 (fluorinert) and copper were used in small volume (0.5-2 ?L) and larger volume (15-20 ?L) thin glass capillary sample cells. Using these plugs, the sample volume efficiency (i.e. ratio of active volume to total sample volume in the microcoil NMR cell) was improved by 6-12-fold without sensitivity and resolution trade-offs. Comparison with laser etched or heat etched microcoil sample cells is provided. The approaches described are potentially useful in metabolomics for biomarkers detection in mass limited biological samples.

Kc, Ravi; Gowda, Yashas N.; Djukovic, Danijel; Henry, Ian D.; Park, Gregory H. J.; Raftery, Daniel

2010-07-01

432

2H NMR studies of supercooled and glassy aspirin  

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

433

2H-NMR studies of supercooled and glassy aspirin  

E-print Network

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

R. Nath; B. Geil; R. Bohmer

2007-01-10

434

Experimental identification of diffusive coupling using 2D NMR.  

PubMed

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique. PMID:25526135

Song, Y-Q; Carneiro, G; Schwartz, L M; Johnson, D L

2014-12-01

435

Experimental Identification of Diffusive Coupling Using 2D NMR  

NASA Astrophysics Data System (ADS)

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique.

Song, Y.-Q.; Carneiro, G.; Schwartz, L. M.; Johnson, D. L.

2014-12-01

436

Toward optimal-resolution NMR of intrinsically disordered proteins  

NASA Astrophysics Data System (ADS)

Proteins, which, in their native conditions, sample a multitude of distinct conformational states characterized by high spatiotemporal heterogeneity, most often termed as intrinsically disordered proteins (IDPs), have become a target of broad interest over the past 15 years. With the growing evidence of their important roles in fundamental cellular processes, there is an urgent need to characterize the conformational behavior of IDPs at the highest possible level. The unique feature of NMR spectroscopy in the context of IDPs is its ability to supply details of their structural and temporal alterations at atomic-level resolution. Here, we briefly review recently proposed NMR-based strategies to characterize transient states populated by IDPs and summarize the latest achievements and future prospects in methodological development. Because low chemical shift dispersion represents the major obstacle encountered when studying IDPs by nuclear magnetic resonance, particular attention is paid to techniques allowing one to approach the physical limits of attainable resolution.

Nová?ek, Ji?í; Žídek, Lukáš; Sklená?, Vladimír

2014-04-01

437

NMR spectroscopy for chemical analysis at low magnetic fields.  

PubMed

This chapter addresses the limits of low-field NMR spectroscopy for chemical analysis and will answer the question of whether high-resolution NMR spectroscopy for chemical analysis of solutions can be achieved with magnetic fields much lower than 0.1 T without losing the chemical information which at high field is derived from the chemical shift and the indirect spin-spin or J-coupling. The focus is on two major issues. First, the thermal spin population differences given by the Boltzmann distribution are small at low field and so is the signal-to-noise-ratio when starting measurements from thermal equilibrium. Second, the possibility of identifying chemical groups is explored at low magnetic fields where the chemical shift can usually no longer be resolved. PMID:22167575

Glöggler, Stefan; Blümich, Bernhard; Appelt, Stephan

2013-01-01

438

Neutron diffraction and MAS NMR of Cesium Tungstate defect pyrochlores  

SciTech Connect

Defect-pyrochlores based on the formulation CsM {sub 0.5}W{sub 1.5}O{sub 6} (M=Ti, Ti/Zr, Zr and Hf) have been studied using neutron diffraction and magic-angle spinning nuclear magnetic resonance (MAS NMR). The results show that structural changes are linearly linked to the change in ionic-radius for the B-site, e.g. the unit cell changes from 10.2763 A for CsTi{sub 0.5}W{sub 1.5}O{sub 6} to 10.3820 A for CsZr{sub 0.4}W{sub 1.6}O{sub 6}. Changes in the NMR chemical shift correlate with the change in electronegativity on the B-site, and show the presence of only one Cs crystal site.

Whittle, K.R. [Department of Earth Sciences, Cambridge Centre for Ceramic Immobilisation (C3i), University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom)]. E-mail: kwhi02@esc.cam.ac.uk; Lumpkin, G.R. [Department of Earth Sciences, Cambridge Centre for Ceramic Immobilisation (C3i), University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom); Ashbrook, S.E. [Department of Earth Sciences, Cambridge Centre for Ceramic Immobilisation (C3i), University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom)

2006-02-15

439

Accelerated NMR spectroscopy with low-rank reconstruction.  

PubMed

Accelerated multi-dimensional NMR spectroscopy is a prerequisite for high-throughput applications, studying short-lived molecular systems and monitoring chemical reactions in real time. Non-uniform sampling is a common approach to reduce the measurement time. Here, a new method for high-quality spectra reconstruction from non-uniformly sampled data is introduced, which is based on recent developments in the field of signal processing theory and uses the so far unexploited general property of the NMR signal, its low rank. Using experimental and simulated data, we demonstrate that the low-rank reconstruction is a viable alternative to the current state-of-the-art technique compressed sensing. In particular, the low-rank approach is good in preserving of low-intensity broad peaks, and thus increases the effective sensitivity in the reconstructed spectra. PMID:25389060

Qu, Xiaobo; Mayzel, Maxim; Cai, Jian-Feng; Chen, Zhong; Orekhov, Vladislav

2015-01-12

440

Improved Halbach sensor for NMR scanning of drill cores.  

PubMed

A lightweight Halbach magnet system for use in nuclear magnetic resonance (NMR) studies on drill cores was designed and built. It features an improved homogeneous magnetic field with a strength of 0.22 T and a maximum accessible sensitive volume. Additionally, it is furnished with a sliding table for automatic scans of cylindrical samples. This device is optimized for nondestructive online measurements of porosity and pore size distributions of water-saturated full cylindrical and split semicylindrical drill cores of different diameters. The porosity of core plugs with diameters from 20 to 80 mm can be measured routinely using exchangeable radiofrequency coils. Advanced NMR techniques that provide 2D T(1)-T(2) correlations with an average measurement time of 30 min and permeability estimates can be performed with a special insert suitable for small core plugs with diameter and length of 20 mm. PMID:17466767

Anferova, Sophia; Anferov, Vladimir; Arnold, Juliane; Talnishnikh, Elena; Voda, Mihai A; Kupferschläger, Klaus; Blümler, Peter; Clauser, Christoph; Blümich, Bernhard

2007-05-01

441

NMR spectroscopy of saccharide-doped PAGAT dosimeters  

NASA Astrophysics Data System (ADS)

The aim of this study was to investigate the chemistry of the PAGAT dosimeters when doped with saccharides and irradiated' using NMR spectroscopy. Three batches of PAGAT gel dosimeters were manufactured. Two of them were doped with 20 % glucose and sucrose' respectively. For each batch' one sample was left unirradiated while the remaining samples were irradiated to different doses. After irradiation' NMR spectra were obtained which clearly showed the composition of the dosimeter and the change in monomer concentration caused by irradiation. In addition' it revealed that the saccharides did not directly participate in the chemical process before and during irradiation but the addition of saccharides resulted in a higher consumption rate of the monomers.

Skyt, P. S.; Berndt, B.; Holloway, L.; Hill, R.; De Deene, Y.

2015-01-01

442

NMR spectroscopic examination of shocked sandstone from meteor crater, Arizona  

SciTech Connect

Solid state silicon-29 nuclear magnetic resonance (NMR) spectroscopy has been used to characterize the formation of high pressure silica polymorphs and amorphous material associated with the shocked Coconino Sandstone from Meteor Crater, Arizona. Five samples of the sandstone were obtained from several locations at the crater to represent a range of shock conditions associated with the hypervelocity impact of a 30 m-diameter meteorite. The NMR spectra for these powdered materials exhibit peaks assigned to quartz, coesite, stishovite, and glass. A new resonance in two of the moderately shocked samples is also observed. This resonance has been identified as a densified form of amorphous silica with silicon in tetrahedra with one hydroxyl group. Such a phase is evidence for a shock-induced reaction between quartz and steam under high pressure conditions. [copyright] 1994 American Institute of Physics

Cygan, R.T.; Boslough, M.B. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)); Kirkpatrick, R.J. (University of Illinois, Urbana, Illinois 61801 (United States))

1994-07-10

443

NMR spectroscopic examination of shocked sandstone from Meteor Crater, Arizona  

SciTech Connect

Solid state silicon-29 nuclear magnetic resonance (NMR) spectroscopy has been used to characterize the formation of high pressure silica polymorphs and amorphous material associated with the shocked Coconino Sandstone from Meteor Crater, Arizona. Five samples of the sandstone were obtained from several locations at the crater to represent a range of shock conditions associated with the hypervelocity impact of a 30 m-diameter meteorite. The NMR spectra for these powdered materials exhibit peaks assigned to quartz, coesite, stishovite, and glass. A new resonance in two of the moderately shocked samples is also observed. This resonance has been identified as a densified form of amorphous silica with silicon in tetrahedra with one hydroxyl group. Such a phase is evidence for a shock-induced reaction between quartz and steam under high pressure conditions.

Cygan, R.T.; Boslough, M.B. [Sandia National Labs., Albuquerque, NM (United States); Kirkpatrick, R.J. [Illinois Univ., Urbana, IL (United States). Dept. of Geology

1993-08-01

444

Cryptophane-folate biosensor for (129)xe NMR.  

PubMed

Folate-conjugated cryptophane was developed for targeting cryptophane to membrane-bound folate receptors that are overexpressed in many human cancers. The cryptophane biosensor was synthesized in 20 nonlinear steps, which included functionalization with folate recognition moiety, solubilizing peptide, and Cy3 fluorophore. Hyperpolarized (129)Xe NMR studies confirmed xenon binding to the folate-conjugated cryptophane. Cellular internalization of biosensor was monitored by confocal laser scanning microscopy and quantified by flow cytometry. Competitive blocking studies confirmed cryptophane endocytosis through a folate receptor-mediated pathway. Flow cytometry revealed 10-fold higher cellular internalization in KB cancer cells overexpressing folate receptors compared to HT-1080 cells with normal folate receptor expression. The biosensor was determined to be nontoxic in HT-1080 and KB cells by MTT assay at low micromolar concentrations typically used for hyperpolarized (129)Xe NMR experiments. PMID:25438187

Khan, Najat S; Riggle, Brittany A; Seward, Garry K; Bai, Yubin; Dmochowski, Ivan J

2015-01-21

445

A converse approach to the calculation of NMR shielding tensors  

SciTech Connect

We introduce an alternative approach to the first-principles calculation of NMR shielding tensors. These are obtained from the derivative of the orbital magnetization with respect to the application of a microscopic, localized magnetic dipole. The approach is simple, general, and can be applied to either isolated or periodic systems. Calculated results for simple hydrocarbons, crystalline diamond, and liquid water show very good agreement with established methods and experimental results.

Thonhauser, Timo; Ceresoli, Davide; Mostofi, Arash A.; Marzari, Nicola N.; Resta, Raffaele; Vanderbilt, David

2009-09-08

446

Optimal isotope labelling for NMR protein structure determinations  

Microsoft Academic Search

Nuclear-magnetic-resonance spectroscopy can determine the three-dimensional structure of proteins in solution. However, its potential has been limited by the difficulty of interpreting NMR spectra in the presence of broadened and overlapping resonance lines and low signal-to-noise ratios. Here we present stereo-array isotope labelling (SAIL), a technique that can overcome many of these problems by applying a complete stereospecific and regiospecific

Masatsune Kainosho; Takuya Torizawa; Yuki Iwashita; Tsutomu Terauchi; Akira Mei Ono; Peter Güntert

2006-01-01

447

Towards Automated Structure-Based NMR Resonance Assignment  

Microsoft Academic Search

\\u000a We propose a general framework for solving the structure-based NMR backbone resonance assignment problem. The core is a novel\\u000a 0-1 integer programming model that can start from a complete or partial assignment, generate multiple assignments, and model\\u000a not only the assignment of spins to residues, but also pairwise dependencies consisting of pairs of spins to pairs of residues.\\u000a It is

Richard Jang; Xin Gao; Ming Li

2010-01-01

448

Inverse problem for in vivo NMR spatial localization  

SciTech Connect

The basic physical problem of NMR spatial localization is considered. To study diseased sites, one must solve the problem of adequately localizing the NMR signal. We formulate this as an inverse problem. As the NMR Bloch equations determine the motion of nuclear spins in applied magnetic fields, a theoretical study is undertaken to answer the question of how to design magnetic field configurations to achieve these localized excited spin populations. Because of physical constraints in the production of the relevant radiofrequency fields, the problem factors into a temporal one and a spatial one. We formulate the temporal problem as a nonlinear transformation, called the Bloch Transform, from the rf input to the magnetization response. In trying to invert this transformation, both linear (for the Fourier Transform) and nonlinear (for the Bloch Transform) modes of radiofrequency excitation are constructed. The spatial problem is essentially a statics problem for the Maxwell equations of electromagnetism, as the wavelengths of the radiation considered are on the order of ten meters, and so propagation effects are negligible. In the general case, analytic solutions are unavailable, and so the methods of computer simulation are used to map the rf field spatial profiles. Numerical experiments are also performed to verify the theoretical analysis, and experimental confirmation of the theory is carried out on the 0.5 Tesla IBM/Oxford Imaging Spectrometer at the LBL NMR Medical Imaging Facility. While no explicit inverse is constructed to ''solve'' this problem, the combined theoretical/numerical analysis is validated experimentally, justifying the approximations made. 56 refs., 31 figs.

Hasenfeld, A.C.

1985-11-01

449

Drug solubilization mechanism of ?-glucosyl stevia by NMR spectroscopy.  

PubMed

We investigated the drug solubilization mechanism of ?-glucosyl stevia (Stevia-G) which was synthesized from stevia (rebaudioside-A) by transglycosylation. (1)H and (13)C NMR peaks of Stevia-G in water were assigned by two-dimensional (2D) NMR experiments including (1)H-(1)H correlation, (1)H-(13)C heteronuclear multiple bond correlation, and (1)H-(13)C heteronuclear multiple quantum coherence spectroscopies. The (1)H and (13)C peaks clearly showed the incorporation of two glucose units into rebaudioside-A to produce Stevia-G, supported by steviol glycoside and glucosyl residue assays. The concentration-dependent chemical shifts of Stevia-G protons correlated well with a mass-action law model, indicating the self-association of Stevia-G molecules in water. The critical micelle concentration (CMC) was 12.0 mg/mL at 37°C. The aggregation number was 2 below the CMC and 12 above the CMC. Dynamic light scattering and 2D (1)H-(1)H nuclear Overhauser effect spectroscopy (NOESY) NMR experiments demonstrated that Stevia-G self-associated into micelles of a few nanometers in size with a core-shell structure, containing a kaurane diterpenoid-based hydrophobic core and a glucose-based shell. 2D (1)H-(1)H NOESY NMR measurements also revealed that a poorly water-soluble drug, naringenin, was incorporated into the hydrophobic core of the Stevia-G micelle. The Stevia-G self-assembly behavior and micellar drug inclusion capacity can achieve significant enhancement in drug solubility. PMID:24508331

Zhang, Junying; Higashi, Kenjirou; Ueda, Keisuke; Kadota, Kazunori; Tozuka, Yuichi; Limwikrant, Waree; Yamamoto, Keiji; Moribe, Kunikazu

2014-04-25

450

NMR study of 4-hydroxy-1-methylpiperidine betaine derivatives  

Microsoft Academic Search

Conformations of two 1-carbethoxymethyl-4-hydroxy-1-methylpiperidinium chlorides (1? and 1?), 4-hydroxy-1-methylpiperidine betaine hydrochlorides (2? and 2?), and 4-hydroxy-1-methylpiperidine betaine inner salts (3? and 3?), having a hydroxyl group at axial (?) or equatorial (?) positions, have been studied by the 1H and 13C NMR spectroscopy. The signals attributed to the equatorial and axial protons at C-2,6 have been found to differentiate the

Z. Dega-Szafran; E. Dulewicz; M. Szafran

2006-01-01

451

Aspects and prospects of high-resolution NMR  

Microsoft Academic Search

Gramicidin-A, a linear pentadecapeptide (with four tryptophans) forming simplest ion channels in lipids, is studied as a cesium-complex in an organic solvent and as an SDS-micellar complex in aqueous solution. Whereas the former is a double-stranded helical dimer, the latter forms a single-stranded head-to-head dimer mimicking ion channels. NMR relaxation gives similar order parameters for tryptophan internal motion in either

Thomas Schulte-Herbruggen

1998-01-01

452

NMR signatures of the active sites in Sn-? zeolite.  

PubMed

Dynamic nuclear polarization surface enhanced NMR (DNP-SENS), Mössbauer spectroscopy, and computational chemistry were combined to obtain structural information on the active-site speciation in Sn-? zeolite. This approach unambiguously shows the presence of framework Sn(IV)-active sites in an octahedral environment, which probably correspond to so-called open and closed sites, respectively (namely, tin bound to three or four siloxy groups of the zeolite framework). PMID:25079352

Wolf, Patrick; Valla, Maxence; Rossini, Aaron J; Comas-Vives, Aleix; Núñez-Zarur, Francisco; Malaman, Bernard; Lesage, Anne; Emsley, Lyndon; Copéret, Christophe; Hermans, Ive

2014-09-15

453

Solid state NMR studies of materials for energy technology  

NASA Astrophysics Data System (ADS)

Presented in this dissertation are NMR investigations of the dynamical and structural properties of materials for energy conversion and storage devices. 1H and 2H NMR was used to study water and methanol transportation in sulfonated poly(arylene ether ketone) based membranes for direct methanol fuel cells (DMFC). These results are presented in chapter 3. The amount of liquid in the membrane and ion exchange capacity (IEC) are two main factors that govern the dynamics in these membranes. Water and methanol diffusion coefficients also are comparable. Chapters 4 and 5 are concerned with 31P and 1H NMR in phosphoric acid doped PBI membranes (para-PBI and 2OH-PBI) as well as PBI membranes containing ionic liquids (H3PO4/PMIH2PO4/PBI). These membranes are designed for higher-temperature fuel cell operation. In general, stronger short and long range interactions were observed in the 2OH-PBI matrix, yielding reduced proton transport compared to that of para-PBI. In the case of H3PO4/PMIH2PO 4/PBI, both conductivity and diffusion are higher for the sample with molar ratio 2/4/1. Finally, chapter 6 is devoted to the 31P NMR MAS study of phosphorus-containing structural groups on the surfaces of micro/mesoporous activated carbons. Two spectral features were observed and the narrow feature identifies surface phosphates while the broad component identifies heterogeneous subsurface phosphorus environments including phosphate and more complex structure multiple P-C, P-N and P=N bonds.

Nambukara Kodiweera Arachchilage, Chandana K.

454

Photo-CIDNP NMR spectroscopy of amino acids and proteins.  

PubMed

Photo-chemically induced dynamic nuclear polarization (CIDNP) is a nuclear magnetic resonance (NMR) phenomenon which, among other things, is exploited to extract information on biomolecular structure via probing solvent-accessibilities of tryptophan (Trp), tyrosine (Tyr), and histidine (His) amino acid side chains both in polypeptides and proteins in solution. The effect, normally triggered by a (laser) light-induced photochemical reaction in situ, yields both positive and/or negative signal enhancements in the resulting NMR spectra which reflect the solvent exposure of these residues both in equilibrium and during structural transformations in "real time". As such, the method can offer - qualitatively and, to a certain extent, quantitatively - residue-specific structural and kinetic information on both the native and, in particular, the non-native states of proteins which, often, is not readily available from more routine NMR techniques. In this review, basic experimental procedures of the photo-CIDNP technique as applied to amino acids and proteins are discussed, recent improvements to the method highlighted, and future perspectives presented. First, the basic principles of the phenomenon based on the theory of the radical pair mechanism (RPM) are outlined. Second, a description of standard photo-CIDNP applications is given and it is shown how the effect can be exploited to extract residue-specific structural information on the conformational space sampled by unfolded or partially folded proteins on their "path" to the natively folded form. Last, recent methodological advances in the field are highlighted, modern applications of photo-CIDNP in the context of biological NMR evaluated, and an outlook into future perspectives of the method is given. PMID:23670104

Kuhn, Lars T

2013-01-01

455

NMR study of nitromethane dissolved in a liquid crystal  

NASA Astrophysics Data System (ADS)

Nitrogen, deuterium, and proton NMR data (quadrupolar splittings and relaxation times) for nitromethane dissolved in poly-?-benzyl- L-glutamate-methylene chloride solutions are reported. The data enable us to derive the nitrogen and deuterium quadrupolar coupling constants in nitromethane, which are 1679 ± 139 and 179 ± 15 kHz, respectively. Correlation times for this molecule are also reported. In addition, the order parameters and relaxation times for methylene chloride are obtained and compared to those of nitromethane.

Loewenstein, A.; Goldsmith, A. D.

456

Studies of 27Al NMR in EuAl4  

NASA Astrophysics Data System (ADS)

EuAl4 orders antiferromagnetically at TN ? 16 K with an effective magnetic moment of 8.02 ?B. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature ?P = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy ?Q are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with ?P = +14 K, which is consistent with that of the magnetic susceptibility. From the K – ? plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/?B for Al(I) site, and -1.823 and -0.264 kOe/?B for Al(II) site, respectively. The values of ?Q of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; ?nuki, Y.; Harima, H.

2015-03-01

457

SAGA: rapid automatic mainchain NMR assignment for large proteins  

Microsoft Academic Search

Here we describe a new algorithm for automatically determining the mainchain sequential assignment of NMR spectra for proteins.\\u000a Using only the customary triple resonance experiments, assignments can be quickly found for not only small proteins having\\u000a rather complete data, but also for large proteins, even when only half the residues can be assigned. The result of the calculation\\u000a is not

Gordon M. Crippen; Aikaterini Rousaki; Matthew Revington; Yongbo Zhang; Erik R. P. Zuiderweg

2010-01-01

458

Accurate calculation of (31)P NMR chemical shifts in polyoxometalates.  

PubMed

We search for the best density functional theory strategy for the determination of (31)P nuclear magnetic resonance (NMR) chemical shifts, ?((31)P), in polyoxometalates. Among the variables governing the quality of the quantum modelling, we tackle herein the influence of the functional and the basis set. The spin-orbit and solvent effects were routinely included. To do so we analysed the family of structures ?-[P2W18-xMxO62](n-) with M = Mo(VI), V(V) or Nb(V); [P2W17O62(M'R)](n-) with M' = Sn(IV), Ge(IV) and Ru(II) and [PW12-xMxO40](n-) with M = Pd(IV), Nb(V) and Ti(IV). The main results suggest that, to date, the best procedure for the accurate calculation of ?((31)P) in polyoxometalates is the combination of TZP/PBE//TZ2P/OPBE (for NMR//optimization step). The hybrid functionals (PBE0, B3LYP) tested herein were applied to the NMR step, besides being more CPU-consuming, do not outperform pure GGA functionals. Although previous studies on (183)W NMR suggested that the use of very large basis sets like QZ4P were needed for geometry optimization, the present results indicate that TZ2P suffices if the functional is optimal. Moreover, scaling corrections were applied to the results providing low mean absolute errors below 1 ppm for ?((31)P), which is a step forward in order to confirm or predict chemical shifts in polyoxometalates. Finally, via a simplified molecular model, we establish how the small variations in ?((31)P) arise from energy changes in the occupied and virtual orbitals of the PO4 group. PMID:25738630

Pascual-Borràs, Magda; López, Xavier; Poblet, Josep M

2015-04-14

459

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine  

SciTech Connect

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

Not Available

1990-02-02

460

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine  

SciTech Connect

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

Not Available

1990-02-02

461

Performance trade-offs in in situ chemostat NMR.  

PubMed

Investigating cell cultures with NMR requires high cell densities to provide adequate signal-to-noise, or scans must be summed over long time periods and short-term events are lost. The mixing within a chemostat can be used to shorten the time required to acquire informative in situ NMR spectra from cell cultures. However, performance trade-offs can occur between net signal, spectral resolution, and oxygenation due to sampling volume, conductivity, gas bubble, and fluid flow effects. These trade-offs and the effect of different mixing regimes were theoretically analyzed to quantify how device design decisions impact performance. The results were found to concur with data from cell-free NMR experiments performed in 18 mS/cm conductivity medium. The results also guided the redesign of an NMR bioreactor in terms of relative radio frequency (rf) coil and sample dimensions and other factors. The design, which entails using chemostat mixing to shunt sample through a rf coil in ca. 0.4 s, provides adequate oxygenation for the 4-16% (v/v) cell suspensions examined. Gains realized include lower conductive losses, better magnetic field homogeneity, and the exclusion of gas bubbles from the sampling zone. These gains enable the acquistion of spectra from dilute (3-4% v/v) Saccharomyces cerevisiae chemostat cultures in 6.9 min with high resolution in both the orthophosphate and the beta-NTP regions. Samples with 16% (v/v) cells also yield useful spectra within 0.5-1.0 min. PMID:10194393

Castro, C D; Koretsky, A P; Domach, M M

1999-01-01

462

High pressure NMR study of a small protein, gurmarin  

Microsoft Academic Search

The effect of pressure on the structure of gurmarin, a globular, 35-residue protein from Gymnema sylvestre, was studied in aqueous environment (95% 1H2O\\/5% 2H2O, pH 2.0) with an on-line variable pressure NMR system operating at 750 MHz. Two-dimensional TOCSY and NOESY spectra were measured as functions of pressure between 1 and 2000 bar at 40?°C . Practically all the proton signals

Kyoko Inoue; Hiroaki Yamada; Toshiaki Imoto; Kazuyuki Akasaka

1998-01-01

463

The Use of Dodecylphosphocholine Micelles in Solution NMR  

NASA Astrophysics Data System (ADS)

Dodecylphosphocholine (DPC) micelles are useful as a model membrane system for solution NMR. Several new observations on dodecylphosphocholine micelles and their interactions with opioid peptides are described. The optimal lipid concentration has been investigated for small peptide NMR studies in DPC micelles for two opioid peptides, a 5-mer and a 17-mer. In contrast to reports in the literature, identical 2D spectra have been observed at low and high lipid concentrations. The chemical shift of resolved peptide proton resonances has been followed as a function of added lipid and indicates that there are changes in the chemical shifts above the critical micelle concentration and up to a ratio of 7:1 (lipid:peptide) for the 17-mer, and 9.6:1 for the 5-mer. These results suggest that conformational changes occur in the peptide significantly above the critical micelle concentration, up to a lipid:peptide ratio which is dependent upon the peptide, here ranging from 7:1 to 9.6:1. To address the stoichiometry more directly, the diffusion coefficients of the lipid alone and the lipid with peptide have been measured using pulsed-field gradient spin-echo NMR experiments. These data have been used to calculate the hydrodynamic radius and the aggregation number of the micelle with and without peptide and show that the aggregation number of the peptide-lipid complex increases at high lipid concentrations without a concomitant change in the peptide conformation. Last, several protonated impurities have been observed in the commercial preparation of DPC which resonate in the amide proton region of the NMR spectrum. These results are significant for researchers using DPC micelles and illustrate that both care in sample preparation and the stoichiometry are important issues with the use of DPC as a model membrane.

Kallick, D. A.; Tessmer, M. R.; Watts, C. R.; Li, C. Y.

464

Mathematical aspects of protein structure determination with NMR orientational restraints  

Microsoft Academic Search

The field of structural biology is becoming increasingly important as new technological developments facilitate the collection\\u000a of data on the atomic structures of proteins and nucleic acids. The solid-state NMR method is a relatively new biophysical\\u000a technique that holds particular promise for determining the structures of peptides and proteins that are located within the\\u000a cell membrane. This method provides information

J. R. Quine; Timothy A. Cross; Michael S. Chapman; Richard Bertram

2004-01-01

465

Electroosmotic drag in polymer electrolyte membranes: an electrophoretic NMR study  

Microsoft Academic Search

Electrophoretic NMR has been applied for the first time to measure electroosmotic drag coefficients Kdrag in polymer electrolyte membranes. Theoretical and experimental details of the method are discussed and measurements of Kdrag as a function of water content and temperature are reported for Nafion® 117 and sulfonated PEEKK. For a given water content n=[H2O]\\/[SO3H], the values for sulfonated PEEKK are

M Ise; K. D Kreuer; J Maier

1999-01-01

466

Peptides containing internal residues of pyroglutamic acid: proton NMR characteristics  

Microsoft Academic Search

The proton NMR characteristics of internal pyroglutamic acid (Glp; 5-oxoproline) residues in seven tripeptides of the general structure Boc-Xxx-Glp-Yyy-NHâ were studied. In general, the chemical shifts of several diagnostic protons moved downfield on going from the Glu-containing peptides (Boc-Xxx-Glu-Yyy-NHâ) to the corresponding Glp-containing peptides. The C-2 proton of the Xxx residue was shifted by about 1.1 ppm. The N-2 proton

Khan

1986-01-01

467

Monoterpene Unknowns Identified Using IR, [to the first power]H-NMR, [to the thirteenth power]C-NMR, DEPT, COSY, and HETCOR  

ERIC Educational Resources Information Center

A study identifies a compound from a set of monoterpenes using infrared (IR) and one-dimensional (1D) nuclear magnetic resonance (NMR) techniques. After identifying the unknown, each carbon and proton signal can be interpreted and assigned to the structure using the information in the two-dimensional (2D) NMR spectra, correlation spectroscopy…

Alty, Lisa T.

2005-01-01

468

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

ERIC Educational Resources Information Center

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

Weizman, Haim

2008-01-01

469