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1

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

2

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

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

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

5

Phosphorus-31 NMR magnetization-transfer measurements of ATP turnover during steady-state isometric muscle contraction in the rat hind limb in vivo  

SciTech Connect

Phosphorus-31 NMR magnetization-transfer measurement have been used to measure the flux between ATP and inorganic phosphate during steady-state isometric muscle contraction in the rat hind limb in vivo. Steady-state contraction was obtained by supramaximal sciatic nerve stimulation. Increasing the stimulation pulse width from 10 to 90 ms, at a pulse frequency of 1 Hz, or increasing the frequency of a 10-ms pulse from 0.5 to 2 Hz resulted in an increase in the flux which was an approximately linear function of the increase in the tension-time integral. The flux showed an approximately linear dependence on the calculated free cytosolic ADP concentration up to an ADP concentration of about 90 {mu}M. The data are consistent with control of mitochondrial ATP synthesis by the cytosolic ADP concentration and indicate that the apparent K{sub m} of the mitochondria for ADP is at least 30 {mu}M.

Brindle, K.M.; Blackledge, M.J.; Challiss, R.A.J.; Radda, G.K. (Univ. of Oxford (England))

1989-05-30

6

Solid-state phosphorus-31 NMR spectroscopy of a multiple-spin system: an investigation of a rhodium-triphosphine complex.  

PubMed

Phosphorus-31 NMR spectra of solid [tris(dimethylphenylphosphine)](2,5-norbornadiene) rhodium(I) hexafluorophosphate have been acquired at several applied magnetic field strengths. The phosphorus nuclei of the three phosphine ligands are spin-spin coupled to each other and to 103Rh, resulting in complex NMR spectra; however, the three phosphorus chemical shift (CS) tensors were determined through the analysis of NMR spectra of slow magic angle spinning and stationary samples. Spectra of spinning samples in rotational resonance and two-dimensional 31P NMR spectra were particularly useful for determining the magnitudes of the indirect spin-spin couplings, and to probe their signs. Despite being in similar environments, the three phosphorus nuclei of the phosphine ligands have distinct CS tensors. In particular, the spans of these tensors, delta11-delta33, range from 80 to 176 ppm. The phosphorus CS tensors have been assigned to specific sites determined by X-ray crystallography, based on a combination of the experimental results and the results of quantum chemical calculations of the phosphorus shielding and 2J(31P,31P) values. The effect of coordination of dimethylphenylphosphine with rhodium has been investigated by comparing calculated phosphorus CS tensors for the uncoordinated ligand with those obtained for the ligands in the complex. PMID:18956090

Bernard, Guy M; Feindel, Kirk W; Wasylishen, Roderick E; Cameron, T Stanley

2008-09-28

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

In Vivo Phosphorus-31 Nuclear Magnetic Resonance (NMR) Spectroscopy Of Cardiac Metabolism: Initial Observations Of Hypoxia And Adrenergic Stimulation  

NASA Astrophysics Data System (ADS)

High resolution 31P nuclear magnetic resonance (NMR) spectroscopy has been applied to the direct, noninvasive examination of phosphorylated substrate metabolism in the myocardium of live rabbits. By the combination of field profiling gradients and a surface, or flat, NMR coil placed directly over the region of the thorax which contains the heart, spatially localized NMR measurements of metabolic function in live animals can be obtained. This technique, termed "topical magnetic resonance" or TMR, has been used to follow the effects of several physiological conditions on the tissue pH and levels of key, energy-rich phosphorylated compounds in the hearts of live, anesthetized rabbits. Changes in tissue content of adenosine triphosphate (ATP), creatine phosphate (CP), and inorganic phosphate (Pi) and the NMR line widths of these species have been observed in animals given appropriate doses of adriamycin for a five day period. These preliminary data demonstrate the potential of spectroscopic NMR techniques in the evaluation of disease states in organs and tissues within the body and the ability to monitor both toxic and therapeutic effects of drugs.

Nunnally, Ray L.

1982-12-01

9

Quadrupole effects in high-resolution phosphorus-31 solid-state NMR spectra of triphenylphosphine copper(I) complexes  

NASA Astrophysics Data System (ADS)

High-resolution 31P solid-state NMR spectra of triphenylphosphine copper(I) complexes, obtained by combining proton dipolar decoupling, proton-phosphorus cross polarization, and magic-angle sample spinning, often reveal asymmetric quartets rather than single resonance lines. These splittings arise from coupling with the nuclear spin {3}/{2} of the quadrupolar copper nucleus. Theoretical NMR spectra of spins I = {1}/{2} coupled to spins S > {1}/{2} are presented for powders spinning at the magic angle. Scalar as well as dipolar interactions are considered for the S = 1 and S = {3}/{2} cases. The magnetic field dependence of the observed asymmetric quartets in bis(triphenylphosphine)copper(I)nitrate can be accounted for by assuming a combination of scalar and dipolar coupling between phosphorus and copper. The spectra allow the determination of the scalar coupling constant, the dipolar coupling constant, and the copper quadrupole constant. Also, their signs can be established.

Menger, E. M.; Veeman, W. S.

10

Characteristics and assessment of biogenic phosphorus in sediments from the multi-polluted Haihe River, China, using phosphorus fractionation and phosphorus-31 nuclear magnetic resonance (31P-NMR)  

NASA Astrophysics Data System (ADS)

We studied the phosphorus (P) pollution, as described by concentrations, distribution and transformation potential, of sediments of the water scarce and heavily polluted Fuyang River, a tributary of the Haihe River, using P fractionation and phosphorus-31 nuclear magnetic resonance (31P-NMR).The sediments of the Fuyang River accumulate significant amounts of inorganic phosphorus (Pi) and organic phosphorus (Po) from industrial and domestic wastewater and agricultural non-point pollution. In terms of their contribution to total phosphorus, the rank order of the P fractions was as follows: H2SO4-P > NaOH-Pi > Res-P > NaOH-Po > KCl-P and their average relative proportions were 69.7:47.5:15.9:2.9:1.0 (the proportion was based on the average proportion of the KCl-P). Seven P compounds were detected by the 31P-NMR analysis. Orthophosphate (Ortho-P: 45.2-92.4%) and orthophosphate monoesters (mono-P: 6.6-45.7%) were the dominant forms. Smaller amounts of pyrophosphates (pyro-P: 0.1-6.6%), deoxyribonucleic acid (DNA-P: 0.3-3.9%), phosphonates (phon-P: 0-3.3%), phospholipids (lipids-P: 0-2.7%) and polyphosphate (poly-P: 0-0.04%) were observed in the sediments. Results of P fractionation and 31P-NMR analysis showed that 35% of Pi was labile P, including KCl-P and NaOH-Pi (Fe-P and Al-P). Biogenic-P accounted for 24% of P in the sediments. Analysis of the relationships between P species and water quality indicated that the Po compounds would mineralize to form ortho-P and would be potentially bioavailable for recycling to surface water, supporting further growth of phytoplankton and leading to algal blooms.

Zhang, W. Q.; Zhang, H.; Tang, W. Z.; Shan, B. Q.

2013-10-01

11

Phosphorus-31, sup 15 N, and sup 13 C NMR of glyphosate: Comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase  

SciTech Connect

The herbicidal dead-end ternary complex (E{sup S3P}{sub Glyph}) of glyphosate (N-(phosphonomethyl)glycine) with 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) and the substrate shikimate 3-phosphate (S3P) has been characterized by {sup 31}P, {sup 15}N, and {sup 13}C NMR. The NMR spectra of EPSPS-bound glyphosate show unique chemical shifts ({delta}) for each of the three nuclei. By {sup 31}P NMR, glyphosate in the dead-end complex is a distinct species 3.5 ppm downfield from free glyphosate. The {sup 13}C signal of glyphosate in the dead-end complex is shifted 4 ppm downfield from that of free glyphosate. The {sup 15}N signal for glyphosate (99%) in the dead-end complex is 5 ppm further downfield than that of any free zwitterionic species and 10 ppm downfield from that of the average free species at pH 10.1. The structures of each ionic state of glyphosate are modeled with force field calculations by using MacroModel. A correlation is made for the {sup 31}P {delta} and the C-P-O bond angle, and the {sup 13}C and {sup 15}N {delta} values are postulated to be related to C-C-O and C-N-C bond angles, respectively. The downfield {sup 31}P chemical shift perturbation for S3P in the EPSPS binary complex is consistent with ionization of the 3-phosphate of S3P upon binding. Comparison with the S3P {sup 31}P {delta} vs pH titration curve specifies predominantly the dianion of the 3-phosphate in the E{sup S3P} binary complex, while the E{sup S3P}{sub Glyph} complex indicates net protonation at the 3-phosphate. Chemical shift perturbations of this latter type may be explained by changes in the O-P-O bond angle.

Castellino, S.; Leo, G.C.; Sammons, R.D.; Sikorski, J.A. (Monsanto Agricultural Company, St. Louis, MO (USA))

1989-05-02

12

Peak assignments for phosphorus-31 nuclear magnetic resonance spectroscopy in pH range 5–13 and their application in environmental samples  

Microsoft Academic Search

Phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy has become popular for the characterization of P species in environmental samples. However, these are commonly made alkaline (pH?>?13) to facilitate sample comparison and ease peak identification, but this may cause hydrolysis of some compounds. This study examined the chemical shift of known P compounds and supplemented this with published data to determine the

R. W. Mcdowell; I. Stewart

2005-01-01

13

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.

14

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

E-print Network

P in several ex vivo soft tissues. Bone is a composite material (8), containing approximately 45Phosphorus-31 MRI of hard and soft solids using quadratic echo line-narrowing Merideth A. Freya) Magnetic resonance imaging (MRI) of solids is rarely attempted. One of the main reasons is that the broader

Haller, Gary L.

15

Phosphorus-31 nuclear magnetic resonance assignments of biogenic phosphorus compounds in sediment of an artificial Fuyangxin River, China.  

PubMed

River eutrophication could drastically influence the phosphorus (P) in the water and sediment. To understand the biogenic-P species, distribution and bioconversion, five sediment samples were collected from an artificial river, and analyzed by phosphorus-31 nuclear magnetic resonance ((31)P-NMR). The P pollution in the water and sediment were both severe. The average concentrations of total P (TP) and solution reactive phosphorus in the water were 3.0 and 2.6 mg L(-1), respectively, which surpass grade V of the national quality standard (China) and should not be used for any purpose. The river sediments accumulated significant inorganic phosphorus (Pi) and organic phosphorus (Po); in the P fractionation, the rank order of the P fractions was as follows: Ca-P?>?NaOH-Pi?>?Res-P?>?KCl-P?>?NaOH-Po, with average relative proportions of 25.1:16.8:6.6:1.7:1:0. Six P compounds were detected in the NaOH-EDTA extract by (31)P-NMR. Mono-P (8.96-29.58 %) was the dominant forms of biogenic-P, and other smaller fractions of biogenic-P were also observed, including pyro-P (0.22-0.86 %), DNA-P (0.75-2.03 %), phon-P (0-1.57 %), and lipids-P (0-2.66 %). The TP and biogenic-P decreased along the direction of flows, with their average relative proportions 7.97:1.20:1.49:1.00:1.00 and 40.87:2.34:3.46:1.60:1 from the upstream to downstream, respectively. The concentration and species of Po in NaOH-Po were lower than found in (31)P-NMR analysis in this research. Thus, the use of 0.25 M NaOH and 50 mM EDTA extracts and solution (31)P-NMR analysis was a more accurate method for quantifying biogenic-P in the river sediments than P fractionation. PMID:24288060

Zhang, Wenqiang; Shan, Baoqing; Zhang, Hong; Tang, Wenzhong

2014-03-01

16

Phosphorus-31 NMR Studies of Cell Wall-Associated Calcium-Phosphates in Ulva lactuca1  

PubMed Central

Phosphate concentrations in the range 0.1 to 2.0 millimolar induced the formation of extracellular amorphous calcium-phosphates in the cell wall of the marine macro algae Ulva lactuca when they were cultivated in light in seawater at 20°C. A broad resonance representing these compounds as well as resonances for extracellular orthophosphate and polyphosphates could be followed by 31P-nuclear magnetic resonance spectroscopy. The presence of the calcium-phosphate made the cells brittle and it inhibited the growth of the macro algae and caused mortality within 1 week. The formation of the calcium-phosphates was influenced by the external phosphate concentration, the extracellular pH and the nature and concentration of the external nitrogen source. Furthermore, no formation of these compounds was observed when Ulva lactuca was cultivated in the dark, at low temperatures (5°C) or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The complex could be removed through washes with ethylenediaminetetraacetate; this treatment did not alter the intracellular pH or the orthophosphate and polyphosphate pools and it restored growth. Images Figure 2 PMID:16666741

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

1989-01-01

17

?-NMR  

NASA Astrophysics Data System (ADS)

The ?-NMR facility at ISAC is constructed specifically for experiments in condensed matter physics with radioactive ion beams. Using co-linear optical pumping, a 8Li + ion beam having a large nuclear spin polarisation and low energy (nominally 30 keV) can be generated. When implanted into materials these ions penetrate to shallow depths comparable to length scales of interest in the physics of surfaces and interfaces between materials. Such low-energy ions can be decelerated with simple electrostatic optics to enable depth-resolved studies of near-surface phenomena over the range of about 2-200 nm. Since the ?-NMR signal is extracted from the asymmetry intrinsic to beta-decay and therefore monitors the polarisation of the radioactive probe nuclear magnetic moments, this technique is fundamentally a probe of local magnetism. More generally though, any phenomena which affects the polarisation of the implanted spins by, for example, a change in resonance frequency, line width or relaxation rate can be studied. The ?-NMR program at ISAC currently supports a number of experiments in magnetism and superconductivity as well as novel ultra-thin heterostructures exhibiting properties that cannot occur in bulk materials. The general purpose zero/low field and high field spectrometers are configured to perform CW and pulsed RF nuclear magnetic resonance and spin relaxation experiments over a range of temperatures (3-300 K) and magnetic fields (0-9 T).

Morris, Gerald D.

2014-01-01

18

COMPARISON OF P FORMS IN ANIMAL MANURE IDENTIFIED BY ENZYMATIC HYDROLYSIS AND SOLUTION P-31 NMR  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both enzymatic hydrolysis and solution phosphorus-31 NMR spectroscopy have been used in characterizing P forms in animal manure. To date, however, there are no reports comparing the P identified by the two methods. In this study, P in 0.25 M NaOH/0.05 M EDTA extracts of dairy manure and poultry litt...

19

PHOSPHORUS-31 Knight Shifts in Amorphous Nickel - and Nickel-Cobalt Alloys.  

NASA Astrophysics Data System (ADS)

Amorphous alloys of the form Ni(,1-x)P(,x) and (Ni(,1-y)Co(,y))(,1-x)P(,x) were prepared by two methods, electroplating (EP) and electroless deposition (EL). Two metastable phases of differing physical densities and NMR properties were noted, and analysed by measurement of the Knight Shifts, relaxation times, physical densities, etc. A comparison is made between the data and a hybridized band model which yields an expression for the enhanced susceptibility of the phosphorous valence band.

Gustafson, Paul Stuart

20

Protective effects of dimethyl amiloride against postischemic myocardial dysfunction in rabbit hearts: Phosphorus 31—nuclear magnetic resonance measurements of intracellular pH and cellular energy  

Microsoft Academic Search

The effects of 5-(N,N-dimethyl)amiloride, a potent and specific Na+-H+ exchange inhibitor, were investigated in isolated perfused rabbit hearts subjected to ischemia and reperfusion. Phosphorus 31–nuclear magnetic resonance spectroscopy was used to monitor intracellular pH, creatine phosphate, ?-adenosine triphosphate, and inorganic phosphate. After cardioplegic arrest with St. Thomas' Hospital solution, normothermic (37º C) global ischemia was induced for 45 minutes, and

Akira Koike; Toshiaki Akita; Yoshihiro Hotta; Kazumi Takeya; Itsuo Kodama; Mitsuya Murase; Toshio Abe; Junji Toyama

1996-01-01

21

Preliminary Study on Hepatocyte-Targeted Phosphorus-31 MRS Using ATP-Loaded Galactosylated Chitosan Oligosaccharide Nanoparticles  

PubMed Central

Background. The clinical applications of hepatic phosphorus-31 magnetic resonance spectroscopy (31P MRS) remain to be difficult because the changes of phosphates between normal hepatic tissues and pathological tissues are not so obvious, and furthermore, up to now there is few literature on hepatocyte-targeted 31P MRS. Materials and Methods. The ATP-loaded Gal-CSO (Gal-CSO/ATP) nanoparticles were prepared and the special cellular uptake of them as evaluated by using HepG-2 tumor cells and A549 tumor cells, respectively. Two kinds of cells were incubated with the nanoparticles suspension, respectively. Then were prepared the cell samples and the enhancement efficiency of ATP peaks detected by 31P MRS was evaluated. Results. The cellular uptake rate of Gal-CSO/ATP nanoparticles in HepG-2 cells was higher than that in A549 cells. Furthermore, the enlarged ATP peaks of Gal-CSO/ATP nanoparticles in HepG-2 cells were higher than those in A549 cells in vitro detected by 31P MRS. Conclusions. Gal-CSO/ATP nanoparticles have significant targeting efficiency in hepatic cells in vitro and enhancement efficiency of ATP peaks in HepG-2 cells. Furthermore, 31P MRS could be applied in the research of hepatic molecular imaging. PMID:24363667

Yu, Ri-Sheng; Zhu, Xiu-Liang; Sun, Jian-Zhong; Shi, Dan; Chen, Ying; Wang, Zhi-Kang; Tang, Ke-Zhong; Du, Yong-Zhong

2013-01-01

22

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

23

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

24

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

25

Moving NMR  

NASA Astrophysics Data System (ADS)

Initiated by the use of NMR for well logging, portable NMR instruments are being developed for a variety of novel applications in materials testing and process analysis and control. Open sensors enable non-destructive testing of large objects, and small, cup-size magnets become available for high throughput analysis by NMR relaxation and spectroscopy. Some recent developments of mobile NMR are reviewed which delineate the direction into which portable NMR is moving.

Blümich, Bernhard; Casanova, Federico; Danieli, Ernesto; Gong, Qingxia; Greferath, Marcus; Haber, Agnes; Kolz, Jürgen; Perlo, Juan

2008-12-01

26

1H NMR studies on the conformational characteristics of 2-thiopyrimidine nucleotides found in transfer RNAs.  

PubMed Central

The molecular conformations of naturally occurring 2-thiopyrimidine nucleosides (5-methylaminomethyl-2-thiouridine, 5-methoxycarbonylmethyl-2-thiouridine and 2-thiocytidine) and 5'-mononucleotides (5-methylaminomethyl-2-thiouridine 5'-monophosphate and 2-thiocytidine 5'-monophosphate) in 2H2O solution were elucidated by analyses of the proton NMR spin-coupling constant, nuclear Overhauser effect, and lanthanide-induced shifts and relaxation enhancements. As monomers, these nucleotides are almost exclusively in the 3E-gg-anti form, even in the absence of ordinary stabilizing factors of this form; i. e., base-stacking and base-pairing interactions with other nucleotide units. This inherent conformational rigidity of the 2-thiopyrimidine units probably contributes to stability of the conformation of tRNA. PMID:379825

Yokoyama, S; Yamaizumi, Z; Nishimura, S; Miyazawa, T

1979-01-01

27

Lanthanide-cyclodextrin complexes as probes for elucidating optical purity by NMR spectroscopy  

SciTech Connect

A multidentate ligand is bonded to cyclodextrins by the reaction of diethylenetriaminepentaacetic dianhydride with 6-mono- and 2-mono(ethylenediamine) derivatives of cyclodextrin. Adding Dy(III) to the cyclodextrin derivatives enhances the enantiomeric resolution in the [sup 1]H NMR spectra of carbionoxamine maleate, doxylamine succinate, pheniramine maleate, propranolol hydrochloride, and tryptophan. The enhancement is more pronounced with the secondary derivative. The Dy(III)-induced shifts can be used to elucidate the geometry of cyclodextrin-substrate inclusion complexes. Lanthanide-induced shifts are reported for complexes of aspartame, tryptophan, propranolol, and 1-anilino-8-naphthalenesulfonate with cyclodextrins, and the relative magnitudes of the shifts agree with previously reported structures of the complexes. 37 refs., 9 figs., 5 tabs.

Wenzel, T.J.; Bogyo, M.S.; Lebeau, E.L. (Bates College, Lewiston, ME (United States))

1994-06-01

28

17O NMR study of diamagnetic and paramagnetic lanthanide(III)-DOTA complexes in aqueous solution.  

PubMed

The complexes between the polyaminocarboxylate DOTA ligand and the whole series of stable lanthanide(III) metal ions, except Gd(3+), were studied in aqueous solution by (17)O NMR. For all of the paramagnetic systems, the (17)O NMR signals of both the nonchelating (O1) and chelating (O2) oxygen atoms could be detected, and for some of them, the signals of both the SAP and TSAP (TSAP') conformational isomers were also observed. Line width data analysis reveals that signal broadening is not dominated by paramagnetic relaxation enhancement, as it was believed to be. The data indicate that quadrupole relaxation and, for some complexes, chemical exchange between the SAP and TSAP isomers are the major contributions to the (17)O NMR line width at 25 °C. Besides, the Fermi contact and pseudocontact contributions to the observed lanthanide-induced shifts could be extracted. The (17)O hyperfine coupling constants determined for O2 in the SAP and TSAP isomers are similar to each other and to the values reported for several Gd(III) complexes comprising fast-exchanging ligands. Interestingly, the results suggest that (17)O NMR should prove to be useful for the study of highly paramagnetic Gd(III) complexes of nonlabile ligands. PMID:25090036

Fusaro, Luca; Luhmer, Michel

2014-08-18

29

Inverse 31P ? 1H NMR cross-polarization in hydrated nanocrystalline calcium hydroxyapatite  

NASA Astrophysics Data System (ADS)

Hydrated nanocrystalline calcium hydroxyapatite was studied using unconventional solid-state NMR technique with cross-polarization from phosphorus-31 to protons (31P ? 1H CP) under magic-angle spinning (MAS). Two peaks were detected: at 0.0 ppm from structural hydroxyl groups and at 5.4 ppm from water. Their intensities were monitored as a function of the contact time. It was found that there were two types of water adsorbed on the crystal surface: typical strongly bound water and distinct, more mobile water associated with a particular 31P environment capable of fast spin-lattice relaxation in the rotating frame. Relative contents of protons in various material compartments were estimated.

Kolmas, Joanna; Kolodziejski, Waclaw

2012-12-01

30

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.

2011-07-01

31

Improved renal transplant preservation using a modified intracellular flush solution (PB-2). Characterization of mechanisms by renal clearance, high performance liquid chromatography, phosphorus-31 magnetic resonance spectroscopy, and electron microscopy studies.  

PubMed

A number of new intracellular renal flush solutions have been found to be more efficacious than Collins-2 (C-2) solution in extending organ viability during simple cold storage. However, the mechanism of action of these solutions remains poorly understood. To delineate better underlying intracellular mechanisms, we studied a modified, simple, hypothermic, intracellular (340 mOsm/kg) flush solution (PB-2). The development of PB-2 solution is based on the ability of some of its individual components to minimize ischemic adenine nucleotide (AN) catabolism and endothelial post "reperfusion injury." Preliminary results in 10 canine autorenal transplants show a significant (P less than 0.02) improvement in renal recovery and viability (recipient posttransplant inulin clearance and survival) after 50 h of cold storage compared with 10 canine kidneys similarly preserved using conventional C-2 flush solution. High performance liquid chromotography (HPLC) studies show a significant (P less than 0.01) loss of AN using C-2, while PB-2 was associated with regeneration of AN within 45 min of reperfusion. Magnetic resonance spectroscopy using phosphorus 31 (31P-MRS) showed more high energy phosphorus metabolites (phosphomonoester and nicotinamide-adenine-dinucleotide phosphate: P less than 0.001) at 50 h cold storage using PB-2 compared with C-2. Electron micrographs (EM) revealed normal microcapillary morphology for the PB-2 group; however, moderate vascular red and white blood cell clumping was observed in the C-2 group. Characterization of the basic preservation mechanisms by HPLC, 31P-MRS, and EM studies indicates that PB-2 solution enhances renal preservation by diminution of both reperfusion injury and the loss of intracellular high energy metabolites that are necessary for viability. PMID:1853517

Bretan, P N; Baldwin, N; Martinez, A; Stowe, N; Scarpa, A; Easley, K; Erturk, E; Jackson, C; Pestana, J; Novick, A C

1991-01-01

32

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.; Larive, Cynthia K.

2011-07-18

33

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

2011-07-19

34

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

35

NMR spectroscopy  

SciTech Connect

In a method of heteronuclear decoupling in high resolution pulsed NMR spectroscopy, during acquisition of signals emanating from a nuclear species to be observed (e.g. carbon-13), irradiation of an interfering nuclear species (e.g. protons) is effected by means of a train of composite pulses, each of which approximately inverts the longitudinal magnetization. The pulses are of two types respectively having opposite R.F. phases, and the train constitutes a repeated sequence which consists of 2 /SUP N/ /sup +1/ pulses of each type (where N is a positive integer) and which has a form chosen in accordance with specific rules to ensure effective decoupling.

Levitt, M.H.; Frenkiel, Th.A.

1984-09-04

36

The Basics of NMR  

NSDL National Science Digital Library

This resource is an online textbook containing information about Nuclear Magnetic Resonance (NMR). Information inlcudes mathhematics of NMR, spin physics, Spectroscopy, pulse sequences, and NMR hardware. The "Practical Considerations" chapter emphasizes spectroscopic techniques.

Hornak, Joseph

2003-10-10

37

Noninvasive detection and monitoring of regional myocardial ischemia in situ using depth-resolved 31P NMR spectroscopy.  

PubMed Central

Phosphorus (31P) NMR spectra showing the relative concentrations of phosphocreatine, ATP, and Pi were recorded noninvasively from localized regions in the left ventricles of dog hearts in situ by using depth-resolved surface-coil spectroscopy at 1.5 T. Proton (1H) NMR surface-coil imaging was used to position 31P NMR coils and to determine the location of depth-resolved volumes immediately prior to 31P examination. Occlusion of the left anterior descending coronary artery produced regional ischemia detected as changes in the ratios of phosphocreatine, ATP, and Pi and by changes in the pH measured from the spectra. Spectral changes were not typically observed in regions adjacent to ischemic myocardium. Reperfusion produced some recovery, and ventricular fibrillation resulted in deterioration in high-energy metabolites. The location and size of ischemic tissue was measured by single-photon-emission computed tomography (SPECT) and gamma-ray counting or by staining excised hearts. The technique should permit the long-term noninvasive monitoring of the metabolic response of the heart to pathologic processes and allow assessment of interventions. Images PMID:3866249

Bottomley, P A; Herfkens, R J; Smith, L S; Brazzamano, S; Blinder, R; Hedlund, L W; Swain, J L; Redington, R W

1985-01-01

38

Investigation into organic phosphorus species in sediments of Baiyangdian Lake in China measured by fractionation and ³¹P NMR.  

PubMed

Organic phosphorus (OP) species in sediments of the Baiyangdian Lake in China was investigated via fractionation and phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy. Results of chemical fractionation showed that different OP fractions ranked in the order: humic acid-P?>?HCl-OP?>?fulvic acid-P???NaHCO(3)-OP?>?residual OP. Labile OP and moderately labile OP, which can be degraded for phytoplankton uptake, contributed to 58.7-68.5% of total extracted OP, indicative of the potential P release from sediments in the lake. (31)P NMR spectroscopy results suggested the rank order of P species present in the NaOH-EDTA extractant of the sediments: orthophosphate?>?monoester-P?>?DNA-P?>?pyrophosphate-P. Phytate, polyphosphates, and phosphonates, which appeared in sediments of some deeper lakes, were not detected in the shallow lake. Significant correlations were identified between total P (TP) in water column and sediment TP, monoester-P and DNA-P, positively indicating that sediment P species, especially OP components, should probably contribute to the contents of P in water column and further to the lake eutrophication. PMID:22322407

Dong, Liming; Yang, Zhifeng; Liu, Xinhui; Liu, Guannan

2012-09-01

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.

2011-03-30

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

2011-04-15

43

Elemental analysis by NMR.  

PubMed

We explore the possibility for elemental analysis by NMR. To keep the efficiency of the signal acquisition common for all spin species, we propose to fix the frequency and vary the magnetic field to cover the isotopes involved in a sample. We introduce constant-frequency receptivity for quantitative elemental analysis in the frequency-fixed NMR experiment. Field-variable NMR experiments are demonstrated using a cryogen-free superconducting magnet. In addition to elemental analysis in liquid solution, solid-state NMR under magic-angle spinning is also described. PMID:23036840

Takeda, Kazuyuki; Ichijo, Naoki; Noda, Yasuto; Takegoshi, K

2012-11-01

44

Flow measurements by NMR  

Microsoft Academic Search

We review the current status of liquid flow velocity studies by pulsed nuclear magnetic resonance (NMR). NMR is a non-invasive method that is most sensitive to protons, so that, combined with the recently developed imaging capabilities, it is now possible to obtain images of hydrodynamic parameters of interest for most common liquids. Such parameters can include, besides velocity, diffusion coefficient,

A. Caprihan; E. Fukushima

1990-01-01

45

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.

2011-06-30

46

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

47

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

48

NMR quantum information processing  

E-print Network

Quantum computing exploits fundamentally new models of computation based on quantum mechanical properties instead of classical physics, and it is believed that quantum computers are able to dramatically improve computational power for particular tasks. At present, nuclear magnetic resonance (NMR) has been one of the most successful platforms amongst all current implementations. It has demonstrated universal controls on the largest number of qubits, and many advanced techniques developed in NMR have been adopted to other quantum systems successfully. In this review, we show how NMR quantum processors can satisfy the general requirements of a quantum computer, and describe advanced techniques developed towards this target. Additionally, we review some recent NMR quantum processor experiments. These experiments include benchmarking protocols, quantum error correction, demonstrations of algorithms exploiting quantum properties, exploring the foundations of quantum mechanics, and quantum simulations. Finally we summarize the concepts and comment on future prospects.

Dawei Lu; Aharon Brodutch; Jihyun Park; Hemant Katiyar; Tomas Jochym-O'Connor; Raymond Laflamme

2015-01-07

49

NMR imaging microscopy  

SciTech Connect

In the past several years, proton nuclear magnetic resonance (NMR) imaging has become an established technique in diagnostic medicine and biomedical research. Although much of the work in this field has been directed toward development of whole-body imagers, James Aguayo, Stephen Blackband, and Joseph Schoeninger of the Johns Hopkins University School of Medicine working with Markus Hintermann and Mark Mattingly of Bruker Medical Instruments, recently developed a small-bore NMR microscope with sufficient resolution to image a single African clawed toad cell (Nature 1986, 322, 190-91). This improved resolution should lead to increased use of NMR imaging for chemical, as well as biological or physiological, applications. The future of NMR microscopy, like that of many other newly emerging techniques, is ripe with possibilities. Because of its high cost, however, it is likely to remain primarily a research tool for some time. ''It's like having a camera,'' says Smith. ''You've got a way to look at things at very fine levels, and people are going to find lots of uses for it. But it is a very expensive technique - it costs $100,000 to add imaging capability once you have a high-resolution NMR, which itself is at least a $300,000 instrument. If it can answer even a few questions that can't be answered any other way, though, it may be well worth the cost.''

Not Available

1986-10-01

50

NMR METHODS IN FOOD CHEMISTRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nuclear Magnetic Resonance (NMR) spectroscopy has enormously facilitated investigations into structural aspects of simple molecules and complex polymers. NMR has developed far beyond the simple running of a proton or carbon spectrum. Today there are literally thousands of “NMR experiments” and varia...

51

Educational NMR Software  

NASA Astrophysics Data System (ADS)

A description of a compilation of computer programs (EduNMRSoft) suitable for teaching NMR at an introductory to advanced level is presented. Each program is categorised and described by function, hardware requirements, availability, author, and references in the list. The compilation is available in electronic form at http://www.chem.umu.se/divisions/fk/EduNMRSoft.html.

Lundberg, Peter

1997-12-01

52

Benford distributions in NMR  

E-print Network

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

Gaurav Bhole; Abhishek Shukla; T. S. Mahesh

2014-06-27

53

224} studied by NMR  

SciTech Connect

7Li nuclear magnetic resonance (NMR) studies have been performed to investigate magnetic properties and spin dynamics of Mn3+ (S = 2) spins in the giant polyoxometalate molecule {Mn40W224}. The 7Li-NMR line width is proportional to the external magnetic field H as expected in a paramagnetic state above 3 K. Below this temperature the line width shows a sudden increase and is almost independent of H, which indicates freezing of the local Mn3+ spins. The temperature dependence of T1 for both 1H and 7Li reveals slow spin dynamics at low temperatures, consistent with spin freezing. The slow spin dynamics is also evidenced by the observation of a peak of 1/T2 around 3 K, where the fluctuation frequency of spins is of the order of ~200 kHz. An explicit form of the temperature dependence of the fluctuation frequency of Mn3+ spins is derived from the nuclear relaxation data.

Furukawa, Y; Fang, X; Kögerler, P

2014-05-14

54

NMR Quantum Computing  

Microsoft Academic Search

Quantum computing is at the forefront of scientific and technological research and development of the 21st century. NMR quantum\\u000a computing is one the most mature technologies for implementing quantum computation. It utilizes the motion of spins of nuclei\\u000a in custom-designed molecules manipulated by RF pulses. The motion is on a nano- or microscopic scale governed by the Schr¨odinger\\u000a equation in

Zhigang Zhang; Goong Chen; Zijian Diao; Philip R. Hemmer

55

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

56

Bayesian reconstruction of projection reconstruction NMR (PR-NMR).  

PubMed

Projection reconstruction nuclear magnetic resonance (PR-NMR) is a technique for generating multidimensional NMR spectra. A small number of projections from lower-dimensional NMR spectra are used to reconstruct the multidimensional NMR spectra. In our previous work, it was shown that multidimensional NMR spectra are efficiently reconstructed using peak-by-peak based reversible jump Markov chain Monte Carlo (RJMCMC) algorithm. We propose an extended and generalized RJMCMC algorithm replacing a simple linear model with a linear mixed model to reconstruct close NMR spectra into true spectra. This statistical method generates samples in a Bayesian scheme. Our proposed algorithm is tested on a set of six projections derived from the three-dimensional 700 MHz HNCO spectrum of a protein HasA. PMID:25218584

Yoon, Ji Won

2014-11-01

57

NMR Spectroscopy in Ionic Liquds  

NASA Astrophysics Data System (ADS)

Today, NMR spectroscopy is the most important analytical tool for synthetically working chemists. This review describes the development of NMR spectroscopic methods for use in ionic liquid media and the state-of-the art in terms of routine analytics as well as modern advanced techniques.

Giernoth, Ralf

58

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

59

NMR flow tube for online NMR reaction monitoring.  

PubMed

In this paper we describe the development of a 5 mm NMR flow tube that can be used in a standard 5 mm NMR probe, enabling the user to conduct experiments on flowing samples or, more specifically, on flowing reaction mixtures. This enables reaction monitoring or kinetic experiments to be conducted by flowing reaction mixtures from a reaction vessel to detection in the coil area of the NMR, without the need for a specialized flow NMR probe. One of the key benefits of this flow tube is that it provides flexibility to be used across a range of available spectrometers of varying magnetic field strengths with a standard 5 mm probe setup. The applicability of this flow tube to reaction monitoring is demonstrated using the reaction of p-phenylenediamine and isobutyraldehyde to form the diimine product. PMID:25375410

Foley, David A; Bez, Eckhard; Codina, Anna; Colson, Kimberly L; Fey, Michael; Krull, Robert; Piroli, Don; Zell, Mark T; Marquez, Brian L

2014-12-16

60

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project during the past reporting 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 in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines the authors are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. The effects of very high MAS rates (>10 kHz) on cross polarization dynamics are also being investigated for similar reasons. The authors have been reinvestigating the prospects of using zero field NMR types of techniques for two dimensional NMR structural analysis of complex organic solids such as coals. Currently MAS spin rates are not sufficiently high to permit zero field in high field NMR for protons in typical organic solids, however they are compatible with {sup 13}C-{sup 13}C dipolar couplings. In collaboration with Dr. Robert Tycko of AT T Bell Laboratories, inventor of the zero field in high field NMR method, the authors have performed the first zero field in high field {sup 13}C NMR experiments. These results are described. 9 refs., 2 figs.

Zilm, K.W.

1989-01-01

61

1H NMR Relaxation in Urea  

E-print Network

Duer. Solid state 13 C CP MAS NMR study of molecular motionsKey Words: NMR; 1 H NMR; 13 C CP/MAS; 15 N CP/MAS; spin-NMR techniques are used to study such systems, the standard cross- polarization/magic angle spinning (CP/

Taylor, Robert E; Bacher, Alfred D; Dybowski, C.

2007-01-01

62

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

63

NMR insights into protein allostery  

PubMed Central

Allosterism is one of nature's principal methods for regulating protein function. Allosterism utilizes ligand binding at one site to regulate the function of the protein by modulating the structure and dynamics of a distant binding site. In this review, we first survey solution NMR techniques and how they may be applied to the study of allostery. Subsequently, we describe several examples of application of NMR to protein allostery and highlight the unique insight provided by this experimental technique. PMID:22198279

Manley, Gregory; Loria, J. Patrick

2014-01-01

64

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

65

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

66

"Decoupled" Proton NMR Spectra  

NASA Astrophysics Data System (ADS)

High-resolution proton NMR spectra are recorded in a new form where all resonances are singlets at the chemical-shift frequencies, with no spin-spin splittings. These "decoupled" proton spectra are derived from two-dimensional J spectra after real Fourier transformation (without frequency discrimination in F1) so that each spin multiplet lies along both the 45° and the 135° diagonal, forming a pattern similar to St. Andrew's cross, with C 4 symmetry. The chemical shifts are located by searching for these centers of symmetry with a postacquisition data-processing algorithm. This is designed to facilitate the separation of overlapping and interpenetrating spin multiplets. The method is illustrated with applications to the 400 MHz high-resolution proton spectra of dehydrotestosterone and 4-androsten-3,17-dione. It is also possible to separate the spectra of components in a mixture and this is illustrated by breaking down the spectrum of an aqueous solution of D-glucose into subspectra from the ? and ? anomers, in order to follow the time evolution of the mutarotation.

Woodley, M.; Freeman, R.

67

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

68

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

69

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report coves the progress made on the title project and summarizes the accomplishments for the project period. Four major areas of inquiry have been pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines we are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. The effects of very high MAS rates (>10 kHz) on cross polarization dynamics are also being investigated for similar reasons. 5 figs.

Zilm, K.W.

1988-01-01

70

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project during the current reporting 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 in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines we are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. This quarter we have focussed on spin lattice relaxation measurements for several of the Argonne coals. 2 figs., 1 tab.

Zilm, K.W.

1988-01-01

71

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project during the current reporting 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 in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines we are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. This quarter we have focused on variable temperature spin lattice relaxation measurements for several of the Argonne coals. 5 figs.

Zilm, K.W.

1988-01-01

72

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project and summarizes the accomplishments for the project period. Four major areas of inquiry have been pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines we are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. The effects of very high MAS rates (>10 kHz) on cross polarization dynamics are also being investigated for similar reasons. 3 figs.

Zilm, K.W.

1988-01-01

73

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

74

Solution NMR conformation of glycosaminoglycans.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy has been giving a pivotal contribution to the progress of glycomics, mostly by elucidating the structural, dynamical, conformational and intermolecular binding aspects of carbohydrates. Particularly in the field of conformation, NOE resonances, scalar couplings, residual dipolar couplings, and chemical shift anisotropy offsets have been the principal NMR parameters utilized. Molecular dynamics calculations restrained by NMR-data input are usually employed in conjunction to generate glycosidic bond dihedral angles. Glycosaminoglycans (GAGs) are a special class of sulfated polysaccharides extensively studied worldwide. Besides regulating innumerous physiological processes, these glycans are also widely explored in the global market as either clinical or nutraceutical agents. The conformational aspects of GAGs are key regulators to the quality of interactions with the functional proteins involved in biological events. This report discusses the solution conformation of each GAG type analyzed by one or more of the above-mentioned methods. PMID:24560989

Pomin, Vitor H

2014-04-01

75

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

76

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

PubMed

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 9.395T, 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. PMID:12932452

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

2003-09-01

77

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...

78

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...

79

Quality Assessment of Horticultural Products by NMR  

Microsoft Academic Search

The potential for developing NMR as an on-line sensor of the internal quality of fruits and vegetables is discussed. The literature on the NMR of horticultural products is first surveyed for potentially useful correlations between NMR characteristics and internal quality factors in commercially important harvested products. This is followed by discussions on the cellular origins of these correlations and of

B. P HILLS; C. J CLARK

2003-01-01

80

Zero field NMR and NQR  

Microsoft Academic Search

Methods are described and demonstrated for detecting the coherent evolution of nuclear spin observables in zero magnetic field with the full sensitivity of high field NMR. The principle motivation is to provide a means of obtaining solid state spectra of the magnetic dipole and electric quadrupole interactions of disordered systems without the line broadening associated with random orientation with respect

D. B. Zax; A. Bielecki; K. W. Zilm; A. Pines; D. P. Weitekamp

1985-01-01

81

Deuterium Exchange Kinetics by NMR.  

ERIC Educational Resources Information Center

Describes a physical chemistry experiment which allows such concepts as kinetics, catalysis, isotope shifts, coupling constants, and the use of nuclear magnetic resonance (NMR) for quantitative work to be covered in the same exercise. Background information, experimental procedures used, and typical results obtained are included. (JN)

Roper, G. C.

1985-01-01

82

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...

83

NMR investigations of molecular dynamics  

NASA Astrophysics Data System (ADS)

NMR spectroscopy is a powerful experimental approach for characterizing protein conformational dynamics on multiple time scales. The insights obtained from NMR studies are complemented and by molecular dynamics (MD) simulations, which provide full atomistic details of protein dynamics. Homologous mesophilic (E. coli) and thermophilic (T. thermophilus) ribonuclease H (RNase H) enzymes serve to illustrate how changes in protein sequence and structure that affect conformational dynamic processes can be monitored and characterized by joint analysis of NMR spectroscopy and MD simulations. A Gly residue inserted within a putative hinge between helices B and C is conserved among thermophilic RNases H, but absent in mesophilic RNases H. Experimental spin relaxation measurements show that the dynamic properties of T. thermophilus RNase H are recapitulated in E. coli RNase H by insertion of a Gly residue between helices B and C. Additional specific intramolecular interactions that modulate backbone and sidechain dynamical properties of the Gly-rich loop and of the conserved Trp residue flanking the Gly insertion site have been identified using MD simulations and subsequently confirmed by NMR spin relaxation measurements. These results emphasize the importance of hydrogen bonds and local steric interactions in restricting conformational fluctuations, and the absence of such interactions in allowing conformational adaptation to substrate binding.

Palmer, Arthur

2011-03-01

84

NMR hyperpolarization techniques for biomedicine.  

PubMed

Recent developments in NMR hyperpolarization have enabled a wide array of new in vivo molecular imaging modalities, ranging from functional imaging of the lungs to metabolic imaging of cancer. This Concept article explores selected advances in methods for the preparation and use of hyperpolarized contrast agents, many of which are already at or near the phase of their clinical validation in patients. PMID:25470566

Nikolaou, Panayiotis; Goodson, Boyd M; Chekmenev, Eduard Y

2015-02-16

85

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

86

SEnD NMR: Sensitivity Enhanced n-Dimensional NMR  

NASA Astrophysics Data System (ADS)

Sparse sampling offers tremendous potential for overcoming the time limitations imposed by traditional Cartesian sampling of indirectly detected dimensions of multidimensional NMR data. However, in many instances sensitivity rather than time remains of foremost importance when collecting data on protein samples. Here we explore how to optimize the collection of radial sampled multidimensional NMR data to achieve maximal signal-to-noise. A method is presented that exploits a rigorous definition of the minimal set of radial sampling angles required to resolve all peaks of interest in combination with a fundamental statistical property of radial sampled data. The approach appears general and can achieve a substantial sensitivity advantage over Cartesian sampling for the same total data acquisition time. Termed Sensitivity Enhanced n-Dimensional or SEnD NMR, the method involves three basic steps. First, data collection is optimized using routines to determine a minimal set of radial sampling angles required to resolve frequencies in the radially sampled chemical shift evolution dimensions. Second, appropriate combinations of experimental parameters (transients and increments) are defined by simple statistical considerations in order to optimize signal-to-noise in single angle frequency domain spectra. Finally, the data is processed with a direct multidimensional Fourier transform and a statistical artifact and noise removal step is employed.

Gledhill, John M.; Wand, A. Joshua

2010-02-01

87

Two dimensional NMR and NMR relaxation studies of coal structure  

SciTech Connect

This report covers the progress made on the title project and summarizes the accomplishments for the project period. Four major areas of inquiry have been pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concerns how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coal models. Along the same lines the author are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. The effects of very high MAS rates (>10 kHz) on cross polarization dynamics are also being investigated for similar reasons. During the last quarter the authors has concentrated on improvements in cross polarization (CP) sequences with a goal of making the CP process insensitive to experimental conditions such as the Hartmann-Hahn mismatch. It has been found that the usual theories of CP are incorrect, and that the CP process is very heterogeneous in nature. This has significant implications on methods typically used in quantifying {sup 13}C CPMAS spectra of coals. 19 refs., 11 figs.

Zilm, K.W.

1989-01-01

88

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

89

SQUID detected NMR and NQR  

Microsoft Academic Search

The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 ??0 Hz?1\\/2 at liquid helium temperatures. Here ?0=?\\/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the

Matthew P. Augustine; Dinh M. TonThat; John Clarke

1998-01-01

90

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

91

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

92

Hyperpolarized (131)Xe NMR spectroscopy.  

PubMed

Hyperpolarized (hp) (131)Xe 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 T(1) 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 (131)Xe 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 (129)Xe SEOP. (131)Xe 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 (131)Xe 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 (131)Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp (131)Xe 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

93

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

94

Analytical Applications of NMR: Summer Symposium on Analytical Chemistry.  

ERIC Educational Resources Information Center

Highlights a symposium on analytical applications of nuclear magnetic resonance spectroscopy (NMR), discussing pulse Fourier transformation technique, two-dimensional NMR, solid state NMR, and multinuclear NMR. Includes description of ORACLE, an NMR data processing system at Syracuse University using real-time color graphics, and algorithms for…

Borman, Stuart A.

1982-01-01

95

Dynamic balancing in NMR double rotor system.  

PubMed

An exact solution to the problem of dynamic balancing in a NMR double rotor system is presented. This will enable one to perform high speed spinning about two intersecting axes. Double rotation is used in solid state NMR to average away second-order broadening, thus enhancing the resolution of spectra from quadrupolar nuclei in solid state NMR. An exact expression for imbalance due to asymmetric distribution of weights about the rotation axes is provided. PMID:11145339

Chakraborty, A

2000-12-01

96

NMR analysis of plant nitrogen metabolism  

Microsoft Academic Search

The analysis of primary and secondary nitrogen metabolism in plants by nuclear magnetic resonance (NMR) spectroscopy is comprehensively reviewed. NMR is a versatile analytical tool, and the combined use of 1H, 2H, 13C, 14N and 15N NMR allows detailed investigation of the acquisition, assimilation and metabolism of nitrogen. The analysis of tissue extracts can be complemented by the in vivo

F. Mesnard; R. G. Ratcliffe

2005-01-01

97

NMR spectroscopic studies of "titanocene"  

E-print Network

recently claimed by Brintzinger and Bercaw as a dimer with two bridging hydrogens and one cyclopentadienyl (C H ) and one cyclopentadienyli- dene (C&H&) ring per titanium for which two possible structures were proposed. v Structure I Structure II... peaks at 3. 9r and approximately 20r. The absorption at 20r along with the infrared evidence conclusively confirms the existence of bridging hydro- gens in the "titanocene" dimer. This is the first known observation by nmr of a titanium hydride. Al...

Birkelbach, Donald Floyd

2012-06-07

98

Picoliter 1H NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

In this study, a 267-?m-diameter solenoid transceiver is used to acquire localized 1H NMR spectra and the measured signal-to-noise ratio (SNR) at 500 MHz is shown to be within 20-30% of theoretical limits formulated by considering only its resistive losses. This is illustrated using a 100-?m-diameter globule of triacylglycerols (˜900 mM) that may be an oocyte precursor in young Xenopus laevis frogs and a water sample containing choline at a concentration often found in live mammalian cells (˜33 mM). In chemical shift imaging (CSI) experiments performed using a few thousand total scans, the choline methyl line is shown to have an acceptable SNR in resolved volume elements containing only 50 pL of sample, and localized spectra are resolved from just 5 pL in the Xenopus globule. These findings demonstrate the feasibility of performing 1H NMR on picoliter-scale sample volumes in biological cells and tissues and illustrate how the achieved SNR in spectroscopic images can be predicted with reasonable accuracy at microscopic spatial resolutions.

Minard, Kevin R.; Wind, Robert A.

2002-02-01

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

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

101

Large NMR signals and polarization asymmetries.  

SciTech Connect

A large modulation in the series Q-meter can lead to nonlinear NMR signals and asymmetric polarization values. With a careful circuit analysis the nonlinearity can be estimated and corrections to polarization can be determined as a function of the strength of the modulation. We describe the recent LAMPF polarized proton target experiment, its NMR measurement and corrections to the measured polarizations.

Penttila, S. I.

1998-11-25

102

NMR-Profiles of Protein Solutions  

PubMed Central

NMR-Profiles are quantitative one-dimensional presentations of two-dimensional [15N,1H]-correlation spectra used to monitor the quality of protein solutions prior to and during NMR structure determinations and functional studies. In our current use in structural genomics projects, a NMR-Profile is recorded at the outset of a structure determination, using a uniformly 15N-labeled micro-scale sample of the protein. We thus assess the extent to which polypeptide backbone resonance assignments can be achieved with given NMR techniques, for example, conventional triple resonance experiments or APSY-NMR. With the availability of sequence-specific polypeptide backbone resonance assignments in the course of the structure determination, an “Assigned NMR-Profile” is generated, which visualizes the variation of the 15N–1H correlation cross peak intensities along the sequence and thus maps the sequence locations of polypeptide segments for which the NMR line shapes are affected by conformational exchange or other processes. The Assigned NMR-Profile provides a guiding reference during later stages of the structure determination, and is of special interest for monitoring the protein during functional studies, where dynamic features may be modulated during physiological functions. PMID:23839514

Pedrini, Bill; Serrano, Pedro; Mohanty, Biswaranjan; Geralt, Michael; Wüthrich, Kurt

2014-01-01

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

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

105

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

106

Quality Assessment of Protein NMR Structures  

PubMed Central

Biomolecular NMR structures are now routinely used in biology, chemistry, and bioinformatics. Methods and metrics for assessing the accuracy and precision of protein NMR structures are beginning to be standardized across the biological NMR community. These include both knowledge-based assessment metrics, parameterized from the database of protein structures, and model vs. data assessment metrics. On line servers are available that provide comprehensive protein structure quality assessment reports, and efforts are in progress by the world-wide Protein Data Bank (wwPDB) to develop a biomolecular NMR structure quality assessment pipeline as part of the structure deposition process. These quality assessment metrics and standards will aid NMR spectroscopists in determining more accurate structures, and increase the value and utility of these structures for the broad scientific community. PMID:24060334

Rosato, Antonio; Tejero, Roberto; Montelione, Gaetano T.

2014-01-01

107

Hyperpolarized Hadamard spectroscopy using flow NMR.  

PubMed

The emergence of the dissolution dynamic nuclear polarization (D-DNP) technique provides an important breakthrough to overcome inherent sensitivity limitations in nuclear magnetic resonance (NMR) experiments. In dissolution DNP, only a small amount of frozen sample is polarized, dissolved, and injected into an NMR spectrometer. Although substantially enhanced NMR signals can be obtained, the single scan nature of this technique a priori impedes the use of correlation experiments, which represent some of the most powerful applications of NMR spectroscopy. Here, an alternative method for multiscan spectroscopy from D-DNP samples utilizing a flow NMR probe is described. Multiple hyperpolarized segments of sample are sequentially injected using a purpose designed device. Hadamard spectroscopy can then be applied for obtaining chemical shift correlation information even from a small number of scans. This capability is demonstrated with a four-scan data set for obtaining the [(13)C,(1)H] correlations in the test molecule 1-butanol. Because of the effects of spin-lattice relaxation and concentration gradients in the D-DNP experiment, the subtractive process for Hadamard reconstruction requires an additional step of intensity scaling. For this purpose, a reconstruction procedure was developed that uses entropy maximization and is robust with respect to noise and signal overlap. In a broader sense, the multiscan NMR as described here is amenable to various correlation NMR experiments, and increases the versatility of D-DNP in small-molecule characterization. PMID:23834163

Chen, Hsueh-Ying; Hilty, Christian

2013-08-01

108

On electrophoretic NMR. Exploring high conductivity samples  

NASA Astrophysics Data System (ADS)

The performance of a new electrophoretic NMR (eNMR) method that uses a Carr-Purcell-Meiboom-Gill echo train with repeated electric field reversal is investigated. We show that this pulse sequence, with acronym CPMGER, yields strongly reduced artifacts from convective flow effects caused by the simultaneous presence of electroosmotic and thermal driving forces. We demonstrate the achieved improvements in various aqueous solutions. Ultimately, the method can be used for obtaining electrophoretic mobilities by eNMR without relying on uncharged reference molecules, otherwise a significant limitation for electrophoretic experiments performed with nuclei other than 1H.

Bielejewski, Micha?; Giesecke, Marianne; Furó, István

2014-06-01

109

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

110

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

111

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

112

Dynamic Nuclear Polarization CARBON-13 NMR of Diamond Films and Rotating Gradient Mas-Nmr Imaging  

NASA Astrophysics Data System (ADS)

^{13}C NMR, with and without dynamic nuclear polarization and ESR measurements are presented on three chemical vapor deposited diamond films. By microwave irradiation with a frequency close to the Larmor frequency of the unpaired electrons present in the diamond films, the ^{13} C signal is enhanced resulting in ^ {13}C direct and cross polarization spectra that are almost impossible to measure without DNP. The resolution of NMR imaging of solids is hampered by the large NMR linewidths of static solid samples. MAS NMR imaging measurements are presented where MAS removes the linebroadening, while the gradient rotates synchronously with the spinner.

Lock, Herman

113

NMR crystallography: The effect of deuteration on high resolution 13 state NMR spectra of a 7-TM protein  

E-print Network

-transmembrane; NMR, nuclear magnetic resonance; MAS, magic angle spinning; DGK, diaglycerol kinase; CP, crossNMR crystallography: The effect of deuteration on high resolution 13 C solid state NMR spectra, and indirect, 9­17 ppm, dimensions). The measured 13 C NMR line-widths observed for both protonated

Watts, Anthony

114

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

115

Bayesian peak picking for NMR spectra.  

PubMed

Protein structure determination is a very important topic in structural genomics, which helps people to understand varieties of biological functions such as protein-protein interactions, protein-DNA interactions and so on. Nowadays, nuclear magnetic resonance (NMR) has often been used to determine the three-dimensional structures of protein in vivo. This study aims to automate the peak picking step, the most important and tricky step in NMR structure determination. We propose to model the NMR spectrum by a mixture of bivariate Gaussian densities and use the stochastic approximation Monte Carlo algorithm as the computational tool to solve the problem. Under the Bayesian framework, the peak picking problem is casted as a variable selection problem. The proposed method can automatically distinguish true peaks from false ones without preprocessing the data. To the best of our knowledge, this is the first effort in the literature that tackles the peak picking problem for NMR spectrum data using Bayesian method. PMID:24184964

Cheng, Yichen; Gao, Xin; Liang, Faming

2014-02-01

116

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

117

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

2014-08-11

118

NMR Quantum Information Processing and Entanglement  

E-print Network

In this essay we discuss the issue of quantum information and recent nuclear magnetic resonance (NMR) experiments. We explain why these experiments should be regarded as quantum information processing (QIP) despite the fact that, in present liquid state NMR experiments, no entanglement is found. We comment on how these experiments contribute to the future of QIP and include a brief discussion on the origin of the power of quantum computers.

Raymond Laflamme; David G. Cory; Camille Negrevergne; Lorenza Viola

2001-10-05

119

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

120

Structural analysis of galactomannans by NMR spectroscopy  

Microsoft Academic Search

The structure of naturally occurring galactomannans was characterized by high resolution NMR spectroscopy involving two-dimensional (2D) NMR measurements of the field gradient DQF-COSY, HMQC, HMBC, and ROESY experiments. Four galactomannans with different proportions of galactose (G) and mannose (M), from fenugreek gum (FG), guar gum (GG), tara gum (TG), and locust bean gum (LG), were investigated. Because these galactomannans had

Tegshi Muschin; Takashi Yoshida

121

"Shim pulses" for NMR spectroscopy and imaging.  

PubMed

A way to use adiabatic radiofrequency pulses and modulated magnetic-field gradient pulses, together constituting a "shim pulse," for NMR spectroscopy and imaging is demonstrated. These pulses capitalize on phase shifts derived from probe gradient coils to compensate for nonlinear intrinsic main magnetic field homogeneity for spectroscopy, as well as for deviations from linear gradients for imaging. This approach opens up the possibility of exploiting cheaper, less-than-perfect magnets and gradient coils for NMR applications. PMID:15591105

Topgaard, Daniel; Martin, Rachel W; Sakellariou, Dimitris; Meriles, Carlos A; Pines, Alexander

2004-12-21

122

NMR exposure sensitizes tumor cells to apoptosis  

Microsoft Academic Search

NMR technology has dramatically contributed to the revolution of image diagnostic. NMR apparatuses use combinations of microwaves\\u000a over a homogeneous strong (1 Tesla) static magnetic field. We had previously shown that low intensity (0.3–66 mT) static magnetic\\u000a fields deeply affect apoptosis in a Ca2+ dependent fashion (Fanelli et al., 1999 FASEBJ., 13;95–102). The rationale of the present study is to examine whether

L. Ghibelli; C. Cerella; S. Cordisco; G. Clavarino; S. Marazzi; M. De Nicola; S. Nuccitelli; M. D'Alessio; A. Magrini; A. Bergamaschi; V. Guerrisi; L. M. Porfiri

2006-01-01

123

NMR analysis of carbohydrate-binding interactions in solution: an approach using analysis of saturation transfer difference NMR spectroscopy.  

PubMed

One of the most commonly used ligand-based NMR methods for detecting ligand binding is saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy. The STD NMR method is an invaluable technique for assessing carbohydrate-lectin interactions in solution, because STD NMR can be used to detect weak ligand binding (Kd ca. 10(-3)-10(-8) M). STD NMR spectra identify the binding epitope of a carbohydrate ligand when bound to lectin. Further, the STD NMR method uses 1H-detected NMR spectra of only the carbohydrate, and so only small quantities of non-labeled lectin are required. In this chapter, I describe a protocol for the STD NMR method, including the experimental procedures used to acquire, process, and analyze STD NMR data, using STD NMR studies for methyl-?-D-galactopyranoside (?-Me-Gal) binding to the C-terminal domain of an R-type lectin from earthworm (EW29Ch) as an example. PMID:25117260

Hemmi, Hikaru

2014-01-01

124

NMR crystallography of ?-poly(L-lactide).  

PubMed

A complementary approach that combines NMR measurements, analysis of X-ray and neutron powder diffraction data and advanced quantum mechanical calculations was employed to study the ?-polymorph of L-polylactide. Such a strategy, which is known as NMR crystallography, to the best of our knowledge, is used here for the first time for the fine refinement of the crystal structure of a synthetic polymer. The GIPAW method was used to compute the NMR shielding parameters for the different models, which included the ?-PLLA structure obtained by 2-dimensional wide-angle X-ray diffraction (WAXD) at -150 °C (model M1) and at 25 °C (model M2), neutron diffraction (WAND) measurements (model M3) and the fully optimized geometry of the PLLA chains in the unit cell with defined size (model M4). The influence of changes in the chain conformation on the (13)C ?(ii) NMR shielding parameters is shown. The correlation between the ?(ii) and ?(ii) values for the M1-M4 models revealed that the M4 model provided the best fit. Moreover, a comparison of the experimental (13)C NMR spectra with the spectra calculated using the M1-M4 models strongly supports the data for the M4 model. The GIPAW method, via verification using NMR measurements, was shown to be capable of the fine refinement of the crystal structures of polymers when coarse X-ray diffraction data for powdered samples are available. PMID:23340670

Pawlak, Tomasz; Jaworska, Magdalena; Potrzebowski, Marek J

2013-03-01

125

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

126

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

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 at low and ultralow temperatures.  

PubMed

Solid state nuclear magnetic resonance (NMR) measurements at low temperatures have been common in physical sciences for many years and are becoming increasingly important in studies of biomolecular systems. This Account reviews a diverse set of projects from my laboratory, dating back to the early 1990s, that illustrate the motivations for low-temperature solid state NMR, the types of information that are available from the measurements, and likely directions for future research. These projects include NMR studies of both physical and biological systems, performed at low (cooled with nitrogen, down to 77 K) and ultralow (cooled with helium, below 77 K) temperatures, and performed with and without magic-angle spinning (MAS). NMR studies of physical systems often focus on phenomena that occur only at low temperatures. Two examples from my laboratory are studies of molecular rotation and orientational ordering in solid C60 at low temperatures and studies of unusual electronic states, called skyrmions, in two-dimensionally confined electron systems within semiconductor quantum wells. To study quantum wells, we used optical pumping of nuclear spin polarizations to enhance their NMR signals. The optical pumping phenomenon exists only at ultralow temperatures. In studies of biomolecular systems, low-temperature NMR has several motivations. In some cases, low temperatures suppress molecular tumbling, thereby permitting solid state NMR measurements on soluble proteins. Studies of AIDS-related peptide/antibody complexes illustrate this effect. In other cases, low temperatures suppress conformational exchange, thereby permitting quantitation of conformational distributions. Studies of chemically denatured states of the model protein HP35 illustrate this effect. Low temperatures and rapid freeze-quenching can also be used to trap transient intermediate states in a non-equilibrium kinetic process, as shown in studies of a transient intermediate in the rapid folding pathway of HP35. NMR sensitivity generally increases with decreasing sample temperature. Therefore, it can be useful to carry out experiments at the lowest possible temperatures, particularly in studies of biomolecular systems in frozen solutions. However, solid state NMR studies of biomolecular systems generally require rapid MAS. A novel MAS NMR probe design that uses nitrogen gas for sample spinning and cold helium only for sample cooling allows a wide variety of solid state NMR measurements to be performed on biomolecular systems at 20-25 K, where signals are enhanced by factors of 12-15 relative to measurements at room temperature. MAS NMR at ultralow temperatures also facilitates dynamic nuclear polarization (DNP), allowing sizeable additional signal enhancements and large absolute NMR signal amplitudes with relatively low microwave powers. Current research in my laboratory seeks to develop and exploit DNP-enhanced MAS NMR at ultralow temperatures, for example, in studies of transient intermediates in protein folding and aggregation processes and studies of peptide/protein complexes that can be prepared only at low concentrations. PMID:23470028

Tycko, Robert

2013-09-17

129

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

130

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

131

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

PubMed

Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures. PMID:24378299

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

2014-01-01

132

NMR standard probe for precision measurement of the free proton NMR frequency  

SciTech Connect

The authors have designed and constructed a special NMR standard probe using a spehrical pure water sample to determine the free proton NMR frequency f{sub p} at high field and an accuracy of 0.04 ppm has been achieved. Since the proton gyromagnetic ratio {gamma}{sub p} is less well known ({approx}0.1 ppm), the free proton NMR frequency measured by the probe may serve as a calibration standard for the magnetic field B. The standard probe can be used at various magnetic field values without introducing any additional magnetic perturbations. The probe is designed in such a way that a cylindrical sample or a small NMR probe can be inserted to replace the 1 cm diameter spherical water sample for systematic studies. Other NMR probes can be calibrated easily against the standard probe using a calibration form. Results will be presented and discussed.

Fei, X.; Hughes, V.W.; Prigl, R.

1995-04-01

133

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

134

NMR characterization of general compartment size distributions.  

PubMed

The influence of molecular diffusion on the nuclear magnetic resonance (NMR) signal can be exploited to estimate compartment size distributions in heterogeneous specimens. Theoretical relationships between the NMR signal intensity at long diffusion times and the moments of a general distribution of isolated pores with characteristic shapes (planar, cylindrical or spherical) are established. A numerical method based on expressing a general diffusion-attenuated NMR signal profile in a series of complete orthogonal basis functions is introduced and subsequently employed to estimate the moments of the compartment size distribution. The results on simulated and real data obtained from controlled water-filled microcapillaries demonstrate the power of the approach to create contrast based not only on the mean of the compartment size but also its variance. The technique can be employed to address a variety of problems such as characterizing distributions of droplet sizes in emulsions and of apparent axon diameters in nerve fascicles. PMID:21709780

Ozarslan, Evren; Shemesh, Noam; Koay, Cheng Guan; Cohen, Yoram; Basser, Peter J

2011-01-01

135

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

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

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

138

Fast multidimensional NMR spectroscopy for sparse spectra.  

PubMed

Multidimensional NMR spectroscopy is widely used for studies of molecular and biomolecular structure. A major disadvantage of multidimensional NMR is the long acquisition time which, regardless of sensitivity considerations, may be needed to obtain the final multidimensional frequency domain coefficients. In this article, a method for under-sampling multidimensional NMR acquisition of sparse spectra is presented. The approach is presented in the case of two-dimensional NMR acquisitions. It relies on prior knowledge about the support in the two-dimensional frequency domain to recover an over-determined system from the under-determined system induced in the linear acquisition model when under-sampled acquisitions are performed. This over-determined system can then be solved with linear least squares. The prior knowledge is obtained efficiently at a low cost from the one-dimensional NMR acquisition, which is generally acquired as a first step in multidimensional NMR. If this one-dimensional acquisition is intrinsically sparse, it is possible to reconstruct the corresponding two-dimensional acquisition from far fewer observations than those imposed by the Nyquist criterion, and subsequently to reduce the acquisition time. Further improvements are obtained by optimizing the sampling procedure for the least-squares reconstruction using the sequential backward selection algorithm. Theoretical and experimental results are given in the case of a traditional acquisition scheme, which demonstrate reliable and fast reconstructions with acceleration factors in the range 3-6. The proposed method outperforms the CS methods (OMP, L1) in terms of the reconstruction performance, implementation and computation time. The approach can be easily extended to higher dimensions and spectroscopic imaging. PMID:24664959

Merhej, Dany; Ratiney, Hélène; Diab, Chaouki; Khalil, Mohamad; Sdika, Michaël; Prost, Rémy

2014-06-01

139

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

140

63Cu NMR study of conducting delafossites  

Microsoft Academic Search

NMR data are presented for the conducting delafossites Y0.99Ca0.01CuO2.65 and LaCuO2.64. These materials exhibit a planar structure with triangular arrays of exchange-coupled S=1\\/2(Cu2+) spins. The two compounds examined show strikingly different quadrupole-broadened NMR powder patterns, which is evidence for different in-plane arrangements of O2- ions. Their doped-hole carrier densities are comparable to those of the superconducting cuprates. In consequence, they

R. E. Walstedt; R. J. Cava; R. F. Bell; J. J. Krajewski; W. F. Peck Jr.

1994-01-01

141

1 MHz bandwidth true NMR SQUID amplifier  

SciTech Connect

We have developed an integrated dc SQUID magnetometer with additional positive feedback (APF) for low frequency true NMR applications. The APF scheme allows direct coupled read out from the SQUID to room temperature electronics and eliminates the need for the conventional modulation scheme, thereby greatly simplifying the flux-locked loop electronics. We have configured our SQUID system for the specific needs of sensitive NMR measurements which include large bandwidth and high slew rate. We have achieved a bandwidth of 1.2 MHz and a slew rate greater than 10{sup 5}{Phi}{sub 0}/s for frequencies above 10 kHz.

Thomasson, S.L.; Gould, C.M. [Univ. of Southern California, Los Angeles, CA (United States)

1995-10-01

142

Recommendations of the wwPDB NMR Validation Task Force  

PubMed Central

As methods for analysis of biomolecular structure and dynamics using nuclear magnetic resonance spectroscopy (NMR) continue to advance, the resulting 3D structures, chemical shifts, and other NMR data are broadly impacting biology, chemistry, and medicine. Structure model assessment is a critical area of NMR methods development, and is an essential component of the process of making these structures accessible and useful to the wider scientific community. For these reasons, the Worldwide Protein Data Bank (wwPDB) has convened an NMR Validation Task Force (NMR-VTF) to work with the wwPDB partners in developing metrics and policies for biomolecular NMR data harvesting, structure representation, and structure quality assessment. This paper summarizes the recommendations of the NMR-VTF, and lays the groundwork for future work in developing standards and metrics for biomolecular NMR structure quality assessment. PMID:24010715

Montelione, Gaetano T.; Nilges, Michael; Bax, Ad; Güntert, Peter; Herrmann, Torsten; Richardson, Jane S.; Schwieters, Charles; Vranken, Wim F.; Vuister, Geerten W.; Wishart, David S.; Berman, Helen M.; Kleywegt, Gerard J.; Markley, John L.

2013-01-01

143

The Muon g-2 Experiment The NMR Probe Circuitry  

E-print Network

The Muon g-2 Experiment The NMR Probe Circuitry Upgrading the Circuit Building the Circuit Future Work Updating NMR Probe Electronics in the Muon g-2 Experiment Audrey Kvam University of Washington September 1, 2014 Audrey Kvam Updating NMR Probe Electronics in the Muon g-2 Experiment #12;The Muon g-2

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

144

Applications of Diffusion Ordered Spectroscopy (DOSY-NMR)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diffusion-ordered NMR (DOSY-NMR) is a powerful, but under-utilized, technique for the investigation of mixtures based on translational diffusion rates. DOSY spectra allow for determination by NMR of components that may differ in molecular weight, geometry or complexation. Typical applications coul...

145

N NMR Investigation of the Covalent Binding of Reduced TNT  

E-print Network

. A comparison of quantitative liquid phase with solid- state CP/MAS 15N NMR indicated that the CP experiment15 N NMR Investigation of the Covalent Binding of Reduced TNT Amines to Soil Humic Acid, Model)slabeled with 15N in the amine positions, were reacted with the IHSS soil humic acid and analyzed by 15N NMR

146

900-MHz NMR: Accelerating Scientific Discovery Scientific Innovation Through Integration  

E-print Network

900-MHz NMR: Accelerating Scientific Discovery Scientific Innovation Through Integration #12;900-MHz NMR: Accelerating Scientific Discovery900-MHz NMR: Accelerating Scientific Discovery Introduction When the U.S. Department of Energy's (DOE's) Office of Biological and Environmental Research approved

147

NMR Structure of the Sea Urchin (Strongylocentrotus purpuratus) Metallothionein MTA  

E-print Network

NMR Structure of the Sea Urchin (Strongylocentrotus purpuratus) Metallothionein MTA Roland Riek1]-metallothionein-A (MTA) of the sea urchin Strongylocentrotus purpuratus was determined by homonuc- lear 1 H NMR Academic Press Keywords: metallothionein; NMR structure; sea urchin; metal-thiolate cluster topology

Riek, Roland

148

Fluid-Rock Characterization and Interactions in NMR Well Logging  

Microsoft Academic Search

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

George J. Hirasaki; Kishore K. Mohanty

2003-01-01

149

Fluid-Rock Characterization and Interactions in NMR Well Logging  

Microsoft Academic Search

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

George J. Hirasaki; Kishore K. Mohanty

2005-01-01

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

Low Field dc SQUID NMR on Room Temperature Samples  

E-print Network

Low Field dc SQUID NMR on Room Temperature Samples and Single Crystal UPt3 by Aya Shibahara is the technique of dc SQUID NMR. Firstly the application of the technique for broadband spectroscopy on room temperature samples is described. The mo- tivation behind this work was to try to obtain SQUID NMR signals

Sheldon, Nathan D.

152

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

SciTech Connect

In a nuclear magnetic resonance (NMR) spectrometer, an improvement is described comprising a semitoroidal primary radio-frequency (RF) coil for irradiating a sample with an alternating magnetic field.

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

1986-05-20

153

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

154

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.; Long, Joanna

2011-07-04

155

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

156

SQUID detected NMR in microtesla magnetic fields.  

PubMed

We have built an NMR system that employs a superconducting quantum interference device (SQUID) detector and operates in measurement fields of 2-25 microT. The system uses a pre-polarizing field from 4 to 30 mT generated by simple room-temperature wire-wound coils that are turned off during measurements. The instrument has an open geometry with samples located outside the cryostat at room-temperature. This removes constraints on sample size and allows us to obtain signals from living tissue. We have obtained 1H NMR spectra from a variety of samples including water, mineral oil, and a live frog. We also acquired gradient encoded free induction decay (FID) data from a water-plastic phantom in the microT regime, from which simple projection images were reconstructed. NMR signals from samples inside metallic containers have also been acquired. This is possible because the penetration skin depth is much greater at the low operating frequencies of this system than for conventional systems. Advantages to ultra-low field NMR measurements include lower susceptibility artifacts caused by high strength polarizing and measurement fields, and negligible line width broadening due to measurement field inhomogeneity, reducing the burden of producing highly homogeneous fields. PMID:15324752

Matlachov, Andrei N; Volegov, Petr L; Espy, Michelle A; George, John S; Kraus, Robert H

2004-09-01

157

Solid-state NMR imaging system  

SciTech Connect

An accessory 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, N.; Dieckman, S.L.; Ellingson, W.A.

1990-01-01

158

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

159

Advanced Laboratory NMR Spectrometer with Applications.  

ERIC Educational Resources Information Center

A description is given of an inexpensive nuclear magnetic resonance (NMR) spectrometer suitable for use in advanced laboratory courses. Applications to the nondestructive analysis of the oil content in corn seeds and in monitoring the crystallization of polymers are presented. (SK)

Biscegli, Clovis; And Others

1982-01-01

160

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

161

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.

162

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

163

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 19, 2010; accepted July 28, 2010. Date of publication October 18, 2010; date of current version

Ham, Donhee

164

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

PubMed

Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was available. Because of its sufficient stability under highly acidic conditions otherwise detrimental for betacyanins, this pigment remained an exemption. Since betalains are most stable in the pH range of 5-7, a new solvent system has been developed allowing improved data acquisition through improved pigment stability at near neutral pH. Thus, not only (1)H, but for the first time also partial (13)C data of betanin, isobetanin, phyllocactin and hylocerenin isolated from red-purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose, Cactaceae] could be indirectly obtained by gHSQC- and gHMQC-NMR experiments. PMID:14759534

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

2004-02-01

165

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

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

2008-12-16

167

Multiecho scheme advances surface NMR for aquifer characterization  

NASA Astrophysics Data System (ADS)

nuclear magnetic resonance (NMR) is increasingly used as a method to noninvasively characterize aquifers. This technology follows a successful history of NMR logging, applied over decades to estimate hydrocarbon reservoir properties. In contrast to logging, however, surface methods have utilized relatively simple acquisition sequences, from which pore-scale properties may not be reliably and efficiently estimated. We demonstrate for the first time the capability of sophisticated multiecho measurements to rapidly record a surface NMR response that more directly reflects aquifer characteristics. Specifically, we develop an adaptation of the multipulse Carr-Purcell-Meiboom-Gill (CPMG) sequence, widely used in logging, to measure the T2 relaxation response in a single scan. We validate this approach in a field surface NMR data set and by direct comparison with an NMR log. Adoption of the CPMG marked a landmark advancement in the history of logging NMR; we have now realized this same advancement in the surface NMR method.

Grunewald, Elliot; Walsh, David

2013-12-01

168

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.

169

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

170

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

PubMed

In this and a previous article (J. Phys. Chem. A 2000, 104, 8244), the range of application for relativistic density functional theory (DFT) is extended to the calculation of nuclear magnetic resonance (NMR) shieldings and chemical shifts in diamagnetic actinide compounds. Two relativistic DFT methods are used, ZORA ("zeroth-order regular approximation") and the quasirelativistic (QR) method. In the given second paper, NMR shieldings and chemical shifts are calculated and discussed for a wide range of compounds. The molecules studied comprise uranyl complexes, [UO(2)L(n)](+/-)(q); UF(6); inorganic UF(6) derivatives, UF(6-n)Cl(n), n = 0-6; and organometallic UF(6) derivatives, UF(6-n)(OCH(3))(n), n = 0-5. Uranyl complexes include [UO(2)F(4)](2-), [UO(2)Cl(4)](2-), [UO(2)(OH)(4)](2-), [UO(2)(CO(3))(3)](4-), and [UO(2)(H(2)O)(5)](2+). For the ligand NMR, moderate (e.g., (19)F NMR chemical shifts in UF(6-n)Cl(n)) to excellent agreement [e.g., (19)F chemical shift tensor in UF(6) or (1)H NMR in UF(6-n)(OCH(3))(n)] has been found between theory and experiment. The methods have been used to calculate the experimentally unknown (235)U NMR chemical shifts. A large chemical shift range of at least 21,000 ppm has been predicted for the (235)U nucleus. ZORA spin-orbit appears to be the most accurate method for predicting actinide metal chemical shifts. Trends in the (235)U NMR chemical shifts of UF(6-n)L(n) molecules are analyzed and explained in terms of the calculated electronic structure. It is argued that the energy separation and interaction between occupied and virtual orbitals with f-character are the determining factors. PMID:12470051

Schreckenbach, Georg

2002-12-16

171

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

172

{sup 129}Xe NMR of mesoporous silicas  

SciTech Connect

The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature-dependent chemical shifts and spin-lattice relaxation time reveal that xenon does not penetrate the pores of the largely disordered (r = 70%) silica. For both r = 0 and 25%, temperature-dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin-lattice relaxation data, which show that xenon is in rapid exchange between the adsorbed and the gas phase.

Pietrass, T.; Kneller, J.M.; Assink, R.A.; Anderson, M.T.

1999-10-21

173

Contrast agents and spectroscopic probes in NMR.  

PubMed

The demand for higher diagnostic specificity has led to the increased use of "foreign" agents to increase tissue contrast and/or spectroscopic sensitivity in NMR studies. The primary agents used to enhance tissue contrast in NMR imaging are paramagnetic. They cause a decrease in the proton T1 of H2O leading to enhanced signal intensity. This effect depends on the large gyromagnetic ratio of the electron, the number of unpaired electrons, the concentration of paramagnetic ions, the number of coordinated water molecules, and the rate of exchange of water. Spectroscopic enhancement has relied primarily on attempt at isotopic enrichment (usually C-13), which causes a direct increase in signal. PMID:6544819

Koutcher, J A; Burt, C T; Lauffer, R B; Brady, T J

1984-04-01

174

NMR studies of nucleic acid dynamics  

NASA Astrophysics Data System (ADS)

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.

Al-Hashimi, Hashim M.

2013-12-01

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

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

177

NMR study of the plutonium hydride system  

Microsoft Academic Search

An NMR study was conducted on protons in the nonstoichiometric plutonium hydride system, PuHx. The following compositions were studied: x=1.78, 2.35, 2.65, and 2.78. The line shapes, Knight shifts (K), spin-spin relaxation times (T2), and spin-lattice relaxation times (T1) were measured in the temperature range of 77-300 K. The results indicate the existence of paramagnetic phases at high temperatures, with

G. Cinader; D. Zamir; Z. Hadari

1976-01-01

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.

2011-06-03

179

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

180

RHODOPSIN-LIPID INTERACTIONS STUDIED BY NMR  

PubMed Central

The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200 nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60 ?m yields on the order of 500 cm2 of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By 2H NMR order parameter measurements it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by 1H saturation-transfer NMR under conditions of magic-angle spinning (MAS), we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. PMID:23374188

Soubias, Olivier; Gawrisch, Klaus

2012-01-01

181

¹³C NMR metabolomics: applications at natural abundance.  

PubMed

(13)C NMR has many advantages for a metabolomics study, including a large spectral dispersion, narrow singlets at natural abundance, and a direct measure of the backbone structures of metabolites. However, it has not had widespread use because of its relatively low sensitivity compounded by low natural abundance. Here we demonstrate the utility of high-quality (13)C NMR spectra obtained using a custom (13)C-optimized probe on metabolomic mixtures. A workflow was developed to use statistical correlations between replicate 1D (13)C and (1)H spectra, leading to composite spin systems that can be used to search publicly available databases for compound identification. This was developed using synthetic mixtures and then applied to two biological samples, Drosophila melanogaster extracts and mouse serum. Using the synthetic mixtures we were able to obtain useful (13)C-(13)C statistical correlations from metabolites with as little as 60 nmol of material. The lower limit of (13)C NMR detection under our experimental conditions is approximately 40 nmol, slightly lower than the requirement for statistical analysis. The (13)C and (1)H data together led to 15 matches in the database compared to just 7 using (1)H alone, and the (13)C correlated peak lists had far fewer false positives than the (1)H generated lists. In addition, the (13)C 1D data provided improved metabolite identification and separation of biologically distinct groups using multivariate statistical analysis in the D. melanogaster extracts and mouse serum. PMID:25140385

Clendinen, Chaevien S; Lee-McMullen, Brittany; Williams, Caroline M; Stupp, Gregory S; Vandenborne, Krista; Hahn, Daniel A; Walter, Glenn A; Edison, Arthur S

2014-09-16

182

1H-NMR microscopy of tablets.  

PubMed

A 1H-nuclear magnetic resonance (NMR) microscopy method was utilized for the first time to determine the porosity distribution of physically intact tablets. The main advantage of this newly developed method was that porosity cross sections through whole tablets or specific locations could be obtained without mechanically destroying the tested tablet. This was achieved by filling tablet cavities with silicone oil under vacuum. The amount of silicone oil locally within the tablet was then determined by 1H-NMR microscopy, revealing the inverse inner structure. To reduce the measuring time, a paramagnetic gadolinium complex was added to the silicone oil. The cross sectional signals produced by 1H-NMR microscopy through the tablet were transformed into a color image by a specially designed computer graphic program. To improve the signal-noise ratio an algorithm of 3D-filtering was introduced. The maximal spatial resolution achieved with this method was about 95 microns for a cube's edge length corresponding to some 380,000 positions in a 9-mm-diameter compression-coated tablet. Uneven porosity distributions within tablets, cracks, or cavities could be visualized with this newly developed method. Different compaction mechanisms were observed with plastic- or brittle-type tablets. The different states of densification during compaction of powders could be detected. The integrity of compression coatings was determined to be dependent on the pressure load and the location of the core within the coat. PMID:7616364

Nebgen, G; Gross, D; Lehmann, V; Müller, F

1995-03-01

183

Cutoff-Free Traveling Wave NMR  

E-print Network

Recently, the concept of traveling-wave NMR/MRI was introduced by Brunner et al. (Nature 457, 994-992 (2009)), who demonstrated MR images acquired using radio frequency (RF) waves propagating down the bore of an MR scanner. One of the significant limitations of this approach is that each bore has a specific cutoff frequency, which can be higher than most Larmor frequencies of at the magnetic field strengths commonly in use for MR imaging and spectroscopy today. We overcome this limitation by using a central conductor in the waveguide and thereby converting it to a transmission line (TL), which has no cutoff frequency. Broadband propagation of waves through the sample thus becomes possible. NMR spectra and images with such an arrangement are presented and genuine traveling wave behavior is demonstrated. In addition to facilitating NMR spectroscopy and imaging in smaller bores via traveling waves, this approach also allows one to perform multinuclear traveling wave experiments (an example of which is shown), an...

Tang, Joel A; Sodickson, Daniel K; Jerschow, Alexej

2011-01-01

184

Sol-gel kinetics by NMR  

SciTech Connect

The chemical synthesis of advanced ceramic and glass materials by the sol-gel process has become an area of increasing activity in the field of material science. The sol-gel process provides a means to prepare homogeneous, high purity materials with tailored chemical and physical properties. This paper surveyed the nuclear magnetic resonance (NMR) studies of silicon-based sol-gel kinetics. A review of the various models which have been used to analyze the chemical kinetics of various sol-gel systems was presented. The utility of NMR spectroscopy was demonstrated in investigating the influence that various reaction conditions have on the reaction pathways by which sol-gel derived materials are synthesized. By observing in a direct fashion the chemical pathway of the sol-gel, it is often possible to relate the final properties of the material to the formulation and reaction conditions of the sol-gel. The study of reaction kinetics by NMR is expected to play an increasingly important role in understanding sol-gel processing and material properties. 15 refs. (DP)

Assink, R.A.; Kay, B.D.

1991-01-01

185

Anisotropy in Tendon Investigated in Vivo by a Portable NMR Scanner, the NMR-MOUSE  

NASA Astrophysics Data System (ADS)

Ordered tissue like tendon is known to exhibit the magic-angle phenomenon in magnetic resonance investigations. Due to the anisotropic structure the transverse relaxation time T2 depends on the orientation of the tendon in the magnetic field. In medical imaging, relaxation measurements of tendon orientation are restricted by the size of the object and the space available in the magnet. For humans, tendon orientation can only be varied within small limits. As a consequence, the magic-angle phenomenon may lead to a misjudgement of tendon condition. It is demonstrated that the NMR-MOUSE (mobile universal surface explorer), a hand-held NMR sensor, can be employed to investigate the anisotropy of T2 in Achilles tendon in vivo. The NMR-MOUSE provides a convenient tool for analyzing the correlation of T2 and the physical condition of tendon.

Haken, R.; Blümich, B.

2000-06-01

186

Multiplexed NMR: An Automated CapNMR Dual-Sample Probe  

PubMed Central

A new generation of micro-scale, nuclear magnetic resonance (CapNMR™) probe technology employs two independent detection elements to accommodate two samples simultaneously. Each detection element in the Dual-Sample CapNMR Probe (DSP) delivers the same spectral resolution and S/N as in a CapNMR probe configured to accommodate one sample at a time. A high degree of electrical isolation allows the DSP to be used in a variety of data acquisition modes. Both samples are shimmed simultaneously to achieve high spectral resolution for simultaneous data acquisition, or alternatively, a flowcell-specific shim set is readily called via spectrometer subroutines to enable acquisition from one sample while the other is being loaded. An automation system accommodates loading of two samples via dual injection ports on an autosampler and two completely independent flowpaths leading to dedicated flowcells in the DSP probe. PMID:20681560

Norcross, James A.; Milling, Craig T.; Olson, Dean L.; Xu, Duanxiang; Audrieth, Anthony; Albrecht, Robert; Ruan, Ke; Likos, John; Jones, Claude; Peck, Timothy L.

2010-01-01

187

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

188

Theoretical and practical aspects of NMR studies of cells.  

PubMed

Various theoretical and practical aspects of biological nuclear magnetic resonance (NMR) spectroscopy that are relevant to the study of immune cells are discussed as a prelude to the following papers in this issue of ImmunoMethods. We explain some of the salient features of modern Fourier-transform NMR spectroscopy, including spectral acquisition, Fourier transformation, signal averaging, apodization, and relaxation phenomena. The major features of the one-dimensional NMR spectrum are summarized prior to a brief description of two-dimensional NMR spectroscopy. We consider various practical questions, such as which NMR-receptive nuclide might be most useful for discerning the metabolic information being sought; in particular, the relative advantages and disadvantages of 1H, 13C, 19F, and 31P NMR spectroscopy are discussed in the context of elucidating metabolic information. The relative merits and pitfalls of using cell extracts, cell suspensions, and perfused immobilized cells for studies of immune cell activation are also considered. PMID:8069538

King, G F; Kuchel, P W

1994-04-01

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

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

191

High-field NMR using resistive and hybrid magnets  

Microsoft Academic Search

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

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

2008-01-01

192

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

2014-03-12

193

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

194

In NMR tube transcription for rapid screening of RNA conformation.  

PubMed

A simple method for rapid structure screening for RNA by NMR is proposed. Target RNA is transcribed in a NMR tube and its spectra are measured without purification. The proposed method, in NMR tube transcription or INTT, was applied for three RNAs for which NMR spectra have been measured by using the conventionally purified samples. By the real-time measuring, increase of imino proton signals and decrease of NTP signals can be observed. It was confirmed that INTT spectra are in general similar to those obtained by the conventional method. INTT can be used for the first-step screening of RNA folding. PMID:25621704

Okui, Saya; Kawai, Gota

2015-02-01

195

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

196

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

197

High resolution 1H NMR of a lipid cubic phase using a solution NMR probe  

NASA Astrophysics Data System (ADS)

The cubic mesophase formed by monoacylglycerols and water is an important medium for the in meso crystallogenesis of membrane proteins. To investigate molecular level lipid and additive interactions within the cubic phase, a method was developed for improving the resolution of 1H NMR spectra when using a conventional solution state NMR probe. Using this approach we obtained well-resolved J-coupling multiplets in the one-dimensional NMR spectrum of the cubic-Ia3d phase prepared with hydrated monoolein. A high resolution t-ROESY two-dimensional 1H NMR spectrum of the cubic-Ia3d phase is also reported. Using this new methodology, we have investigated the interaction of two additive molecules, L-tryptophan and ruthenium-tris(2,2-bipyridyl) dichloride (rubipy), with the cubic mesophase. Based on the measured chemical shift differences when changing from an aqueous solution to the cubic phase, we conclude that L-tryptophan experiences specific interactions with the bilayer interface, whereas rubipy remains in the aqueous channels and does not associate with the lipid bilayer.

Boyle-Roden, E.; Hoefer, N.; Dey, K. K.; Grandinetti, P. J.; Caffrey, M.

2007-11-01

198

NMR-based quantification of organic diphosphates  

PubMed Central

Phosphorylated compounds are ubiquitous in life. Given their central role, many such substrates and analogues have been prepared for subsequent evaluation. Prior to biological experiments, it is typically necessary to determine the concentration of the target molecule in solution. Here we describe a method where concentrations of stock solutions of organic diphosphates and bisphosphonates are quantified using 31P NMR spectroscopy with standard instrumentation using a capillary tube with a secondary standard. The method is specific and is applicable down to a concentration of 200 ?M. The capillary tube provides the reference peak for quantification and deuterated solvent for locking. PMID:20833124

Lenevich, Stepan

2010-01-01

199

Dynamic NMR cardiac imaging in a piglet.  

PubMed

NMR echo-planar imaging (EPI) has been used in a realtime mode to visualise the thorax of a live piglet. Moving pictures are available on an immediate image display system which demonstrates dynamic cardiac function. Frame rates vary from one per cardiac cycle in a prospective stroboscopic mode with immediate visual output to a maximum of 10 frames per second yielding up to six looks in one piglet heart cycle, but using a visual playback mode. A completely new system has been used to obtain these images, features of which include a probe assembly with 22 cm access and an AP400 array processor for real-time data processing. PMID:6652414

Doyle, M; Rzedzian, R; Mansfield, P; Coupland, R E

1983-12-01

200

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

201

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

202

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

203

NMR observation of Tau in Xenopus oocytes  

NASA Astrophysics Data System (ADS)

The observation by NMR spectroscopy of microinjected 15N-labelled proteins into Xenopus laevis oocytes might open the way to link structural and cellular biology. We show here that embedding the oocytes into a 20% Ficoll solution maintains their structural integrity over extended periods of time, allowing for the detection of nearly physiological protein concentrations. We use these novel conditions to study the neuronal Tau protein inside the oocytes. Spectral reproducibility and careful comparison of the spectra of Tau before and after cell homogenization is presented. When injecting Tau protein into immature oocytes, we show that both its microtubule association and different phosphorylation events can be detected.

Bodart, Jean-François; Wieruszeski, Jean-Michel; Amniai, Laziza; Leroy, Arnaud; Landrieu, Isabelle; Rousseau-Lescuyer, Arlette; Vilain, Jean-Pierre; Lippens, Guy

2008-06-01

204

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...

205

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

206

Algorithmic cooling and scalable NMR quantum computers  

PubMed Central

We present here algorithmic cooling (via polarization heat bath)—a powerful method for obtaining a large number of highly polarized spins in liquid nuclear-spin systems at finite temperature. Given that spin-half states represent (quantum) bits, algorithmic cooling cleans dirty bits beyond the Shannon's bound on data compression, by using a set of rapidly thermal-relaxing bits. Such auxiliary bits could be implemented by using spins that rapidly get into thermal equilibrium with the environment, e.g., electron spins. Interestingly, the interaction with the environment, usually a most undesired interaction, is used here to our benefit, allowing a cooling mechanism. Cooling spins to a very low temperature without cooling the environment could lead to a breakthrough in NMR experiments, and our “spin-refrigerating” method suggests that this is possible. The scaling of NMR ensemble computers is currently one of the main obstacles to building larger-scale quantum computing devices, and our spin-refrigerating method suggests that this problem can be resolved. PMID:11904402

Boykin, P. Oscar; Mor, Tal; Roychowdhury, Vwani; Vatan, Farrokh; Vrijen, Rutger

2002-01-01

207

NMR assessment on bone simulated under microgravity  

NASA Astrophysics Data System (ADS)

Introduction Microgravity-induced bone loss has been suggested to be similar to disuse-osteoporosis on Earth which constitutes a challenging public health problem No current non-destructive method can provide the microstructural changes in bone particularly on cortical bone Recently the authors have applied low field nuclear magnetic resonance NMR spin-spin relaxation technique and computational analysis method to determine the porosity pore size distribution and microdamage of cortical bone 1-3 The studies by the authors have shown that this technology can be used to characterize microstructural changes as well as bone water distribution bound and mobile water changes of weightless treated simulating a microgravity condition turkey and mouse cortical bone We further determinate that the NMR spin-spin relaxation time T 2 spectrum derived parameters can be used as descriptions of bone quality e g matrix water distribution and porosity size distributions and alone or in combination with current techniques bone mineral density measurements more accurately predict bone mechanical properties Methods underline Bone sample preparation Two kinds of animal samples were collected and prepared for designed experiments from SUNY Cortical bones of the mid-diaphyses of the ulnae of 1-year-old male turkeys were dissected from freshly slaughtered animals Eight samples were categorized from normal or control and four samples were 4-week disuse treated by functionally isolated osteotomies disuse A total of 12

Ni, Q.; Qin, Y.

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 probe for dynamic-angle spinning  

SciTech Connect

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

Mueller, K.T.; Chingas, G.C.; Pines, A. (Materials Sciences Division, Lawrence Berkeley Laboratory and Department of Chemistry, University of California, Berkeley, California 94720 (USA))

1991-06-01

210

Ab initio NMR Chemical Shift Calculations for Biomolecular Systems  

E-print Network

(i.e. J-coupling, relaxation time and NOE), can provide invaluable information on the three-dimensional4 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

211

Two-dimensional NMR spectroscopy. Applications for chemists and biochemists  

SciTech Connect

Two-dimensional nuclear magnetic resonance spectroscopy (2-D NMR) has become a very powerful class of experiments (in the hands of an adept scientist) with broad adaptability to new situations. It is the product of a happy marriage between modern pulse FT-NMR technology, with its large memory and high-speed computers, and the physicists and chemists who love to manipulate spin systems. Basic 2-D experiments are now a standard capability of modern NMR spectrometers, and this timely book intends to make 2-D NMR users of those who are familiar with normal 1-D NMR. The 2-D NMR goal is correlation of the lines of the observed NMR spectrum with other properties of the system. This book deals with applications to high-resolution spectrum analysis, utilizing either coupling between the NMR-active nuclei or chemical exchange to perform the correlation. The coupling can be scalar (through bonds) or direct through space (within 5 A). The coupling may be homonuclear (between like nuclei) or heteronuclear.

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

1987-01-01

212

Journal of Biomolecular NMR, 26: 4968, 2003. KLUWER/ESCOM  

E-print Network

Journal of Biomolecular NMR, 26: 49­68, 2003. KLUWER/ESCOM © 2003 Kluwer Academic Publishers, fusion, MAS, melittin, membrane, NMR, peptide, solid-state, two- dimensional Abstract 2D slow ­ bicinchoninic acid; CP ­ cross-polarization; CSA ­ chemical shift anisotropy; DQ ­ double quantum; DRAWS

Weliky, David

213

Study of Paramagnetic Chromocenes by Solid-State NMR Spectroscopy  

E-print Network

-state NMR spectroscopy to polycrystalline paramagnetic sand- wich compounds was tested for chromocene (Cp2CrStudy of Paramagnetic Chromocenes by Solid-State NMR Spectroscopy Janet Blu¨mel,* Martin Herker), deuteriated chromocene (Cp2Cr-d10), and decamethyl- chromocene (Cp*2Cr). The bulk properties of paramagnetic

Bluemel, Janet

214

Journal of Biomolecular NMR, 22: 175179, 2002. KLUWER/ESCOM  

E-print Network

Journal of Biomolecular NMR, 22: 175­179, 2002. KLUWER/ESCOM © 2002 Kluwer Academic Publishers by residue-pair selected solid-state NMR Mei Honga,, R. Andrew McMillanb & Vincent P. Conticellob a anisotropy, elastin, protein conformation, selective and extensive labeling, SPECIFIC CP Abstract We

Hong, Mei

215

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

216

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

217

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

218

NMR structure validation in relation to dynamics and structure determination.  

PubMed

NMR spectroscopy is a key technique for understanding the behaviour of proteins, especially highly dynamic proteins that adopt multiple conformations in solution. Overall, protein structures determined from NMR spectroscopy data constitute just over 10% of the Protein Data Bank archive. This review covers the validation of these NMR protein structures, but rather than describing currently available methodology, it focuses on concepts that are important for understanding where and how validation is most relevant. First, the inherent characteristics of the protein under study have an influence on quality and quantity of the distinct types of data that can be acquired from NMR experiments. Second, these NMR data are necessarily transformed into a model for use in a structure calculation protocol, and the protein structures that result from this reflect the types of NMR data used as well as the protein characteristics. The validation of NMR protein structures should therefore take account, wherever possible, of the inherent behavioural characteristics of the protein, the types of available NMR data, and the calculation protocol. These concepts are discussed in the context of 'knowledge based' and 'model versus data' validation, with suggestions for questions to ask and different validation categories to consider. The principal aim of this review is to stimulate discussion and to help the reader understand the relationships between the above elements in order to make informed decisions on which validation approaches are the most relevant in particular cases. PMID:25444697

Vranken, Wim F

2014-10-01

219

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...

220

Fluid-Rock Characterization and Interactions in NMR Well Logging  

Microsoft Academic Search

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,

George J. Hirasaki; Kishore K. Mohanty

2003-01-01

221

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.

222

"Perfecting" WATERGATE: clean proton NMR spectra from aqueous solution.  

PubMed

A simple modification of the WATERGATE solvent suppression method greatly improves the quality of (1)H NMR spectra obtainable from samples in H(2)O. The new method allows (1)H signals to be measured even when close in chemical shift to the signal of water, as for example in the NMR spectra of carbohydrates. PMID:23192194

Adams, Ralph W; Holroyd, Chloe M; Aguilar, Juan A; Nilsson, Mathias; Morris, Gareth A

2013-01-14

223

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.

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

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

226

{sup 17}O NMR investigations of oxidative degradation in polymers  

SciTech Connect

We have initiated studies using both solution and solid state magic angle spinning {sup 17}O NMR for a series of oxidatively aged polymers. This short note reports the solution {sup 17}O NMR for oxidatively degraded polypropylene, ethylene-propylene-diene, polyisoprene, and nitrile rubber. Enriched O{sub 2} is used during the accelerated aging. 3 figs, 7 refs.

Alam, T.M.; Celina, M.; Assink, R.A.; Gillen, K.T.; Clough, R.L.

1996-12-31

227

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...

228

Development of portable NMR polarimeter system for polarized HD target  

E-print Network

A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 kg to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.

T. Ohta; M. Fujiwara; K. Fukuda; H. Kohri; T. Kunimatsu; C. Morisaki; S. Ono; M. Tanaka; K. Ueda; M. Uraki; M. Utsuro; S. Y. Wang; M. Yosoi

2011-03-09

229

Development of portable NMR polarimeter system for polarized HD target  

E-print Network

A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 kg to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.

Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

2011-01-01

230

Adiabatic Single Scan Two-Dimensional NMR Spectrocopy Philippe Pelupessy*,  

E-print Network

on the use adiabatic pulses, for single scan two-dimensional NMR experiments (Frydman et al., Proc. Nat. Acad- and heteronuclear experiments are presented. Introduction The introduction of two-dimensional (2D) experiments has revolutionized the field of nuclear magnetic resonance (NMR).1,2 Unfortunately, these experiments are inherently

231

Biomedical Applications of NMR Imaging and Diffusion Studies  

E-print Network

Biomedical Applications of NMR Imaging and Diffusion Studies Using Thermal And Hyperpolarized Xenon by ..................................................................................................... David Nelson Chairman, Department of Physics #12;Biomedical Applications of NMR Imaging and Diffusion residence time in these compartments. Our successful generation of a magnetic resonance (MR) image of laser

Walsworth, Ronald L.

232

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

233

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

234

Biological membrane structure by solid-state NMR.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy, and particularly solid-state NMR spectroscopy, is a method of choice to study the structure and dynamics of both the lipid and the protein components of model and biological membranes. Different approaches have been developed to study these systems in which the restricted molecular motions result in broad NMR spectra. This contribution will first present an overview of the different techniques used to study lipid bilayers, namely 31p, 2H and 13C solid-state NMR spectroscopy. On the other hand, the study of the structure of membrane peptides and proteins is a rapidly growing field and several methods developed in the last two decades will be presented. These methods allow the investigation of protein systems for which structural information is often difficult to obtain by techniques such as X-ray diffraction and multidimensional solution NMR. PMID:11471756

Auger, M

2000-10-01

235

Membrane Protein Structure and Dynamics from NMR Spectroscopy  

PubMed Central

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. PMID:22136620

Hong, Mei; Zhang, Yuan; Hu, Fanghao

2014-01-01

236

Perfusion of cell spheroids for study by NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Many anchorage-dependent types of cells can be cultured in suspension as small clumps of defined size known as spheroids. These spheroids are particularly suited for study with NMR spectroscopy because, unlike suspensions of single cells, they can be perfused without being carried along with the perfusate, thus eliminating the need for filters or gels. We have successfully maintained human breast cancer cells (MCF-7) and Chinese hamster cells (V 79) in a physiological steady state as spheroids for more than 80 hours in a 10 mm NMR tube using a simple and inexpensive perfusion setup which requires no modification of NMR instrumentation. Although we were primarily interested in obtaining 31P NMR spectra, cell mass was sufficiently high that natural abundance 13C NMR spectra were also readily obtained.

Lin, Peck-Sun; Blumenstein, Michael; Mikkelsen, Ross B.; Schmidt-Ullrich, Rupert; Bachovchin, William W.

237

Earth's field NMR flow meter: preliminary quantitative measurements.  

PubMed

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 (0-1m/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. PMID:25033240

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

2014-08-01

238

Introducing the gNMR Program in an Introductory NMR Spectrometry Course to Parallel Its Use by Spectroscopists  

ERIC Educational Resources Information Center

An approach that is useful to any introductory nuclear magnetic resonance (NMR) spectroscopy course is developed. This approach to teaching NMR spectrometry includes spectral simulation along with the traditional elements of hands-on instrument use and structure elucidation to demonstrate the connection between simulating a spectrum and structure…

Rummey, Jackie M.; Boyce, Mary C.

2004-01-01

239

1H and 13C NMR data to aid the identification and quantification of residual solvents by NMR spectroscopy.  

PubMed

We present reference data and a javascript web page which allow the rapid identification and quantification of residual solvents by NMR. The data encompass all of the ICH-prescribed solvents and were obtained for a number of NMR solvents. We also present an example of its application. PMID:15809983

Jones, Ian C; Sharman, Gary J; Pidgeon, Julia

2005-06-01

240

Ab initio simulation of paramagnetic NMR spectra: the 31P NMR in oxovanadium phosphates.  

PubMed

A theoretical analysis of the temperature-dependent (31)P NMR signals for the ambient pressure vanadyl pyrophosphate AP-(VO)(2)P(2)O(7) and the oxovanadium hemihydrate hydrogenophosphate VO(HPO(4)).0.5H(2)O phases is reported. The ab initio calculation of the magnetic exchange parameters and the hyperfine constants gives access to an original ab initio simulation of NMR spectra. Such a strategy allows one to clarify the crystallographic nature of the different experimentally studied phases. For the vanadyl pyrophosphate ambient pressure structure, our simulations strongly support the presence of a monoclinic phase. Based on this assumption, hyperfine constants are extracted from the fit of the experimental data. These values are directly compared to the ab initio ones. PMID:12656632

Petit, Sébastien; Borshch, Serguei A; Robert, Vincent

2003-04-01

241

NMR Experimental Demonstration of Probabilistic Quantum Cloning  

E-print Network

The method of quantum cloning is divided into two main categories: approximate and probabilistic quantum cloning. The former method is used to approximate an unknown quantum state deterministically, and the latter can be used to faithfully copy the state probabilistically. So far, many approximate cloning machines have been experimentally demonstrated, but probabilistic cloning remains an experimental challenge, as it requires more complicated networks and a higher level of precision control. In this work, we designed an efficient quantum network with a limited amount of resources, and performed the first experimental demonstration of probabilistic quantum cloning in an NMR quantum computer. In our experiment, the optimal cloning efficiency proposed by Duan and Guo [Phys. Rev. Lett. \\textbf{80}, 4999 (1998)] is achieved.

Hongwei Chen; Dawei Lu; Bo Chong; Gan Qin; Xianyi Zhou; Xinhua Peng; Jiangfeng Du

2011-04-19

242

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

243

Developments in high resolution NMR of inorganic solids  

SciTech Connect

From the foundations laid by the pioneering work of J.S. Waugh at M.I.T., a number of advances in resolution and sensitivity have contributed to modem solid state nuclear magnetic resonance (NMR) and its applications to materials science. Among the recent developments at Berkeley aimed at high resolution spectroscopy in solids are multiple-quantum NMR, cross polarization of quadrupoles, multiple-axis spinning methods, zero field magnetic resonance and optically pumped xenon NMR of surfaces. Following the lecture we shall hear an update on the condition of Hartmann and Hahn.

Pines, A. [Lawrence Berkeley National Lab., CA (United States)

1996-12-31

244

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

245

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

246

13 C NMR and mass spectrometry of soil organic matter  

Microsoft Academic Search

Liquid state, high resolution 13C NMR spectroscopy and mass spectrometry were used to study the composition and structure of soil organic matter (SOM) using\\u000a soil extracts from two long-term experiments at the Rothamsted Experimental Station. Both one- and two-dimensional NMR techniques\\u000a were applied. 13C NMR sub-spectra of the CH\\u000a n\\u000a (n=0...3) groups, obtained by the Distortionless Enhancement by Polarisation Transfer

Galya I. Ivanova; Edward W. Randall

2003-01-01

247

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

248

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

249

Solid-State NMR Studies of Amyloid Fibril Structure  

NASA Astrophysics Data System (ADS)

Current interest in amyloid fibrils stems from their involvement in neurodegenerative and other diseases and from their role as an alternative structural state for many peptides and proteins. Solid-state nuclear magnetic resonance (NMR) methods have the unique capability of providing detailed structural constraints for amyloid fibrils, sufficient for the development of full molecular models. In this article, recent progress in the application of solid-state NMR to fibrils associated with Alzheimer's disease, prion fibrils, and related systems is reviewed, along with relevant developments in solid-state NMR techniques and technology.

Tycko, Robert

2011-05-01

250

NMR studies of metallic tin confined within porous matrices  

SciTech Connect

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

Charnaya, E. V. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Institute of Physics, St. Petersburg State University, St. Petersburg, Petrodvorets 198504 (Russian Federation); Tien, Cheng; Lee, M. K. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Kumzerov, Yu. A. [A. F. Ioffe Physico-Technical Institute, RAS, St. Petersburg 194021 (Russian Federation)

2007-04-01

251

The biochemical and elemental compositions of marine plankton: A NMR perspective  

E-print Network

resonance (CP/MAS 13 C NMR). Using a mixing model that relates NMR spectral data to biochemical compositionThe biochemical and elemental compositions of marine plankton: A NMR perspective J.I. Hedges a,*, J. Although preliminary, this 13 C NMR-based estimate indicates elemental compositions and respiratory oxygen

Long, Bernard

252

Advances of high-resolution NMR techniques in the structural and metabolic analysis of plant biochemistry  

Microsoft Academic Search

Rapid progress in instrumentation and software made nuclear magnetic resonance spectroscopy (NMR) one of the most powerful analytical methods in biological sciences. Whereas the development of multidimensional NMR pulse sequences is an ongoing process, a small subset of two-dimensional NMR experiments is typically sufficient for the rapid structure determination of small metabolites. The use of sophisticated three- and four-dimensional NMR

Wolfgang Eisenreich; Adelbert Bacher

2007-01-01

253

Protein NMR Techniques, 3rd Methods in Molecular Biology, Springer Verlag (Humana Press), 2011  

E-print Network

Protein NMR Techniques, 3rd ed. Methods in Molecular Biology, Springer Verlag (Humana Press), 2011, 518 pages. The field of protein NMR spectroscopy has rapidly expanded into new areas of biochemistry of the latest innovations in the field of protein NMR. It focuses on the application of NMR to biochemistry

Linsley, Braddock K.

254

Broadband adiabatic inversion pulses for cross polarization in wideline solid-state NMR spectroscopy  

E-print Network

Broadband adiabatic inversion pulses for cross polarization in wideline solid-state NMR polarization Solid-state NMR Wideline NMR Stationary sample CPMG WURST­CPMG 119 Sn 207 Pb 195 Pt a b s t r a c t Efficient acquisition of ultra-wideline solid-state NMR powder patterns is a continuing challenge. In par

Frydman, Lucio

255

The PAW/GIPAW approach for computing NMR parameters: a new dimension added to NMR study of solids.  

PubMed

In 2001, Mauri and Pickard introduced the gauge including projected augmented wave (GIPAW) method that enabled for the first time the calculation of all-electron NMR parameters in solids, i.e. accounting for periodic boundary conditions. The GIPAW method roots in the plane wave pseudopotential formalism of the density functional theory (DFT), and avoids the use of the cluster approximation. This method has undoubtedly revitalized the interest in quantum chemical calculations in the solid-state NMR community. It has quickly evolved and improved so that the calculation of the key components of NMR interactions, namely the shielding and electric field gradient tensors, has now become a routine for most of the common nuclei studied in NMR. Availability of reliable implementations in several software packages (CASTEP, Quantum Espresso, PARATEC) make its usage more and more increasingly popular, maybe indispensable in near future for all material NMR studies. The majority of nuclei of the periodic table have already been investigated by GIPAW, and because of its high accuracy it is quickly becoming an essential tool for interpreting and understanding experimental NMR spectra, providing reliable assignments of the observed resonances to crystallographic sites or enabling a priori prediction of NMR data. The continuous increase of computing power makes ever larger (and thus more realistic) systems amenable to first-principles analysis. In the near future perspectives, as the incorporation of dynamical effects and/or disorder are still at their early developments, these areas will certainly be the prime target. PMID:21612895

Charpentier, Thibault

2011-07-01

256

RPF: a quality assessment tool for protein NMR structures.  

PubMed

We describe the RPF web server, a quality assessment tool for protein NMR structures. The RPF server measures the 'goodness-of-fit' of the 3D structure with NMR chemical shift and unassigned NOESY data, and calculates a discrimination power (DP) score, which estimates the differences between the fits of the query structures and random coil structures to these experimental data. The DP-score is an accuracy predictor of the query structure. The RPF server also maps local structure quality measures onto the 3D structure using an online molecular viewer, and onto the NMR spectra, allowing refinement of the structure and/or NOESY peak list data. The RPF server is available at: http://nmr.cabm.rutgers.edu/rpf. PMID:22570414

Huang, Yuanpeng Janet; Rosato, Antonio; Singh, Gautam; Montelione, Gaetano T

2012-07-01

257

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

258

Journal of Biomolecular NMR 28: 357367, 2004. KLUWER/ESCOM  

E-print Network

mutagenesis for production and NMR assignments of human eIF2 Takuhiro Ito & Gerhard Wagner Department to a known fold for improving solubility and stability of the target protein by tenfold. Combining all

259

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

260

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

261

NMR Spectroscopy for Thin Films by Magnetic Resonance Force Microscopy  

PubMed Central

Nuclear magnetic resonance (NMR) is a fundamental research tool that is widely used in many fields. Despite its powerful applications, unfortunately the low sensitivity of conventional NMR makes it difficult to study thin film or nano-sized samples. In this work, we report the first NMR spectrum obtained from general thin films by using magnetic resonance force microscopy (MRFM). To minimize the amount of imaging information inevitably mixed into the signal when a gradient field is used, we adopted a large magnet with a flat end with a diameter of 336??m that generates a homogeneous field on the sample plane and a field gradient in a direction perpendicular to the plane. Cyclic adiabatic inversion was used in conjunction with periodic phase inversion of the frequency shift to maximize the SNR. In this way, we obtained the 19F NMR spectrum for a 34?nm-thick CaF2 thin film. PMID:24217000

Won, Soonho; Saun, Seung-Bo; Lee, Soonchil; Lee, SangGap; Kim, Kiwoong; Han, Yunseok

2013-01-01

262

A Demonstration of Imaging on an NMR Spectrometer.  

ERIC Educational Resources Information Center

Described is a simple demonstration that relates the techniques of magnetic resonance imaging (MRI) used in medicine and nuclear magnetic resonance (NMR) spectroscopy. Included are materials, procedures, and probable results. (KR)

Hull, L. A.

1990-01-01

263

NMR Studies of Protein Structure and Dynamics  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. This thesis describes applications of 2D homonuclear NMR techniques to the study of protein structure and dynamics in solution. The sequential assignments for the 3G-residue bovine Pancreatic Polypeptide (bPP) are reported. The secondary and tertiary structure of bPP in solution has been determined from experimental NMR data. bPP has a well defined C-terminal alpha-helix and a rather ordered conformation in the N-terminal region. The two segments are joined by a turn which is poorly defined. Both the N- and the C-terminus are highly disordered. The mean solution structure of bPP is remarkably similar to the crystal structure of avian Pancreatic Polypeptide (aPP). The average conformations of most side-chains from the alpha-helix of bPP in solution are closely similar to those of aPP in the crystalline state. A large number of side-chains of bPP, however, show significant conformational averaging in solution. The 89-residue kringle domain of urokinase from both human and recombinant sources has been investigated. Sequential assignments based primarily on the recombinant sample and the determination of secondary structure are presented. Two helices have been identified; one of these corresponds to that reported for t-PA kringle 2, but does not exist in other kringles with known structures. The second helix is thus far unique to the urokinase kringle. Three antiparallel beta-sheets and three tight turns have also been identified. The tertiary fold of the molecule conforms broadly to that found for other kringles. Three regions in the urokinase kringle exhibit high local mobility; one of these, the Pro56-Pro62 segment, forms part of the proposed binding site. The other two mobile regions are the N- and C-termini which are likely to form the interfaces between the kringle and the other two domains (EGF and protease) in urokinase. The differential dynamic behaviours of the kringle and protease domains in urokinase have been analysed through calculations of the transverse relaxation and lineshapes of resolved methyl resonances in the intact urokinase spectra. The study has provided strong evidence of large domain mobility between the kringle and protease domains. The results are in good agreement with those obtained from simulations of 2D cross peaks in the aromatic region of the spectra. Similar results are also obtained from calculations applied to miniplasminogen. It appears therefore that the mobility and structural independence between the kringle and protease domains might be a general feature of fibrinolytic proteins.

Li, Xiang

264

Introducing Hyperpolarized Xenon131 Directly Detected by NMR Spectroscopy  

Microsoft Academic Search

Previously, high-field NMR and MRI applications of hyperpolarized (hp) noble gasses focused on the isotopes helium-3 (spin I = 1\\/2), xenon-129 (spin I = 1\\/2) [1], and more recently krypton-83 (spin I = 9\\/2) [2]. In this contribution, hp xenon-131 (spin I = 3\\/2) was generated by spin-exchange optical pumping and separated from the rubidium vapor for high field NMR

Karl Stupic; Zackary Cleveland; Galina Pavlovskaya; Thomas Meersmann

2007-01-01

265

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

266

The Xplor-NIH NMR molecular structure determination package  

Microsoft Academic Search

We announce the availability of the Xplor-NIH software package for NMR biomolecular structure determination. This package consists of the pre-existing XPLOR program, along with many NMR-specific extensions developed at the NIH. In addition to many features which have been developed over the last 20 years, the Xplor-NIH package contains an interface with a new programmatic framework written in C++. This

Charles D. Schwieters; John J. Kuszewski; Nico Tjandra; G. Marius Clorec

2003-01-01

267

Rapid characterization of molecular diffusion by NMR spectroscopy.  

PubMed

An NMR-based approach for rapid characterization of translational diffusion of molecules has been developed. Unlike the conventional method of acquiring a series of 2D (13)C and (1)H spectra, the proposed approach involves a single 2D NMR spectrum, which can be acquired in minutes. Using this method, it was possible to detect the presence of intermediate oligomeric species of diphenylalanine in solution during the process of its self-assembly to form nanotubular structures. PMID:25331210

Pudakalakatti, Shivanand M; Chandra, Kousik; Thirupathi, Ravula; Atreya, Hanudatta S

2014-11-24

268

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

269

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

270

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

271

Ultrafast 2D NMR: An Emerging Tool in Analytical Spectroscopy  

NASA Astrophysics Data System (ADS)

Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago, a so-called ultrafast (UF) approach was proposed, capable of delivering arbitrary 2D NMR spectra involving any kind of homo- or heteronuclear correlation, in a single scan. During the intervening years, the performance of this subsecond 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool experiencing an expanded scope of applications. This review summarizes the principles and main developments that have contributed to the success of this approach and focuses on applications that have been recently demonstrated in various areas of analytical chemistry—from the real-time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications.

Giraudeau, Patrick; Frydman, Lucio

2014-06-01

272

NMR analysis on microfluidic devices by remote detection  

SciTech Connect

We present a novel approach to perform high-sensitivity NMR imaging and spectroscopic analysis on microfluidic devices. The application of NMR, the most information rich spectroscopic technique, to microfluidic devices remains a challenge because the inherently low sensitivity of NMR is aggravated by small fluid volumes leading to low NMR signal, and geometric constraints resulting in poor efficiency for inductive detection. We address the latter by physically separating signal detection from encoding of information with remote detection. Thereby, we use a commercial imaging probe with sufficiently large diameter to encompass the entire device, enabling encoding of NMR information at any location on the chip. Because large-diameter coils are too insensitive for detection, we store the encoded information as longitudinal magnetization and flow it into the outlet capillary. There, we detect the signal with optimal sensitivity using a solenoidal microcoil, and reconstruct the information encoded in the fluid. We present a generally applicable design for a detection-only microcoil probe that can be inserted into the bore of a commercial imaging probe. Using hyperpolarized 129Xe gas, we show that this probe enables sensitive reconstruction of NMR spectroscopic information encoded by the large imaging probe while keeping the flexibility of a large coil.

McDonnell, Erin E.; Han, SongI; Hilty, Christian; Pierce,Kimberly; Pines, Alexander

2005-08-15

273

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

274

Comprehensive automation for NMR structure determination of proteins.  

PubMed

This chapter gives an overview of automated protein structure determination by nuclear magnetic resonance (NMR) with the UNIO protocol that enables high to full automation of all NMR data analysis steps involved. Four established algorithms, namely, the MATCH algorithm for sequence-specific resonance assignment, the ASCAN algorithm for side-chain resonance assignment, the CANDID algorithm for NOE assignment, and the ATNOS algorithm for signal identification in NMR spectra, are assembled into three principal UNIO NMR data analysis components (MATCH, ATNOS/ASCAN, and ATNOS/CANDID) that are accessed thanks to a particularly intuitive and flexible, yet powerful graphical user interface (GUI). UNIO is designed to work independently or in association with other NMR software. The principal data analysis components for sequence-specific backbone, side-chain and NOE assignment may be run separately or out of sequence. User-intervention at individual stages is encouraged and facilitated by graphical tools included for the preparation, analysis, validation, and subsequent presentation of the NMR structure. PMID:22167686

Guerry, Paul; Herrmann, Torsten

2012-01-01

275

Ultra-broadband NMR probe: numerical and experimental study of transmission line NMR probe.  

PubMed

We have reinvestigated a transmission line NMR probe first published by Lowe and co-workers in 1970s [Rev. Sci. Instrum. 45 (1974) 631; 48 (1977) 268] numerically and experimentally. The probe is expected to be ultra-broadband, thus might enable new types of solid-state NMR experiments. The NMR probe consists of a coil and capacitors which are connected to the coil at regular intervals. The circuit is the same as a cascaded LC low-pass filter, except there are nonzero mutual inductances between different coil sections. We evaluated the mutual inductances by Neumann's formula and calculated the electrical characteristics of the probe as a function of a carrier frequency. We found that they were almost the same as those of a cascaded LC low-pass filter, when the inductance L of a section was estimated from the inductance of the whole coil divided by the number of the sections, and if C was set to the capacitance in a section. For example, the characteristic impedance of a transmission line coil is given by Z=(L/C)(1/2). We also calculated the magnitude and the distribution of RF magnetic field inside the probe. The magnitude of RF field decreases when the carrier frequency is increased because the phase delay between neighboring sections is proportional to the carrier frequency. For cylindrical coils, the RF field is proportional to (pinu/2nu(d))(1/2)exp(-nu/nu(d)), where the decay frequency nu(d) is determined by the dimensions of the coil. The observed carrier frequency thus must be much smaller than the decay frequency. This condition restricts the size of transmission line coils. We made a cylindrical coil for a 1H NMR probe operating below 400 MHz. It had a diameter 2.3mm and a pitch 1.2mm. Five capacitors of 6pF were connected at every three turns. The RF field strength was 40 and 60 kHz at the input RF power 100 W by a calculation and by experiments, respectively. The calculations showed that the RF field inhomogeneity along the coil axis was caused by a standing wave of current, which arose from the reflections at the coil ends. The calculation showed that the homogeneity could be improved by decreasing the pitch near the both ends and making their impedance close to that at the center. PMID:12810012

Kubo, Atsushi; Ichikawa, Shinji

2003-06-01

276

Fat Emulsification Measured Using NMR Transverse Relaxation  

NASA Astrophysics Data System (ADS)

This paper presents a novel method of measuring the droplet size in oil-in-water emulsions. It is based on changes in the NMR transverse relaxation rate due to the effect of microscopic magnetic susceptibility differences between fat droplets and the surrounding water. The longitudinal and transverse relaxation rates of a series of emulsions with constant oil volume fraction and five different mean droplet sizes, in the range 0.4-20.9 ?m, were measured in vitro at 37°C using EPI. While the longitudinal relaxation rate 1/ T1 did not change significantly, 1/ T2 was observed to increase with mean droplet size. The measured changes in 1/ T2 were found to be in good agreement with results predicted from proton random walk simulations, and were also consistent with analytical solutions based on an outer sphere relaxation model. Measurements of 1/ T2 on emulsions with a higher oil volume fraction, and on emulsions of a fixed size where the water phase was doped with gadolinium to modulate the susceptibility difference between the phases, also showed the predicted behavior. As part of this study the susceptibility difference between olive oil and water was measured to be 1.55 ppm.

Marciani, L.; Ramanathan, C.; Tyler, D. J.; Young, P.; Manoj, P.; Wickham, M.; Fillery-Travis, A.; Spiller, R. C.; Gowland, P. A.

2001-11-01

277

NMR Study of Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

^13C NMR experiments have been carried out for single-wall carbon nanotubes (SWNTs), which were produced by using non-ferromagnetic Rh-Pt mixed catalysts. Hydrogen peroxide was used to remove amorphous carbon particles in the raw soot almost perfectly. From the line shape analysis of the ^13C spectrum measured at 100.1MHz(9.4 T), the shift tensor was evaluated to be (?_11,?_22,?_33)=(192,186,132) ppm. Small anisotropic value(??= -57 ppm) compared with that reported for MWNTs suggests that this SWNTs sample contains metallic tubes with larger electronic density of states at the Fermi level than that of multi-wall carbon nanotubes(MWNTs) sample. We also performed ^13C spin lattice relaxation time(T_1) . It is found that SWNTs follows a Korringa-like behavior(T_1^o T=940^o60(sec.K)) in the temperature region between 4.2 K and 100 K. Alkali metal-doping effects and hydrogen uptake effects will be discussed.

Ogata, Hironori; Bandow, Syunji; Kuno, Shogo; Saito, Yahachi

2000-03-01

278

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

279

Proton 1H- and Phosphorus 31P-MR spectroscopy (MRS) in asymptomatic HIV-positive patients  

PubMed Central

Introduction HIV infection is accompanied by a variety of neurological disorders. Depression of cell-mediated immunity is followed by the development of central nervous system opportunistic infections/tumours, and frequently by the occurrence of the AIDS dementia complex (ADC). However, the pathophysiology of the emergence of neuro-AIDS is still unknown. Despite the development of cognitive impairments, the early diagnosis, objectification and quantification of the existence and extent of this impairment during infection are difficult to recognize in each individual case. To support the early diagnosis of ADC, there is a need for additional, non-invasive diagnostic methods. In this study, it is of interest to answer the clinically relevant question of whether magnetic resonance spectroscopy can detect changes in the cerebral metabolism of asymptomatic HIV-positive patients and is possibly suitable for the early diagnosis and prevention of HIV encephalopathy. Methods A group of 13 asymptomatic, HIV-positive patients with combined antiretroviral therapy (cART) and 13 healthy controls were examined with 2D 1H-MRS and 3D 31P-MRS at 3T. The patients were treated with cART for at least 12 months. Changes in the absolute concentrations of phosphorylated metabolites (ATP), N-acetyl-aspartate, creatine, myo-Isonitol, glutamate/glutamine and choline-containing compounds were compared with that of control subjects. Results Asymptomatic HIV-positive patients had significantly lower N-acetyl-aspartate in the white matter in a frontal and parietal target region. The other evaluated metabolites in the 1H MRS showed no significant difference between the HIV-positive patients and healthy controls. The 31P-MRS detected significant elevated values regarding the choline-containing compounds PEth, GPE and PCho. Conclusions This spectroscopic study revealed a significantly lower N-acetyl-aspartate in the white matter in a frontal and parietal cerebral target region in asymptomatic, HIV-positive patients as an early sign of neuronal disintegration. The 31P-MRS detected significant elevated values regarding the choline-containing compounds PEth, GPE and PCho as an early sign of gliosis. Furthermore we could show that with the use of 1H-MRS and 31P-MRS cerebral metabolites can be reliably detected and measured in HIV-positive patients. The 1H-MRS and 31P-MRS is therefore suited as a diagnostic tool for early cerebral metabolic changes in HIV-positive patients. PMID:25394084

Schuettfort, Gundolf; Hattingen, Elke; Pilatus, Ulrich; Stephan, Christoph; Wolf, Timo; Goepel, Siri; Haberl, Annette; Blasel, Stella; Zanella, Freidhelm; Brodt, Hans-Reinhard; Bickel, Markus

2014-01-01

280

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...

281

NMR Study of Strontium Binding by a Micaceous Mineral  

SciTech Connect

The nature of strontium binding by soil minerals directly affects the transport and sequestration/remediation of radioactive strontium species released from leaking high-level nuclear waste storage tanks. However, the molecular-level structure of strontium binding sites has seldom been explored in phyllosilicate minerals by direct spectroscopic means and is not well-understood. In this work, we use solid-state NMR to analyze strontium directly and indirectly in a fully strontium-exchanged synthetic mica of nominal composition Na4Mg6Al4Si4O20F4. Thermogravimetric analysis, X-ray diffraction analysis, and NMR evidence supports that heat treatment at 500 °C for 4 h fully dehydrates the mica, creating a hydrogen-free interlayer. Analysis of the strontium NMR spectrum of the heat-treated mica shows a single strontium environment with a quadrupolar coupling constant of 9.02 MHz and a quadrupolar asymmetry parameter of 1.0. These quadrupolar parameters are consistent with a highly distorted and asymmetric coordination environment that would be produced by strontium cations without water in the coordination sphere bound deep within the ditrigonal holes. Evidence for at least one additional strontium environment, where proton-strontium couplings may occur, was found via a 1H-87Sr transfer of populations by double resonance NMR experiment. We conclude that the strontium cations in the proton-free interlayer are observable by 87Sr NMR and bound through electrostatic interactions as nine coordinate inner-sphere complexes sitting in the ditrigonal holes. Partially hydrated strontium cations invisible to direct 87Sr NMR are also present and located on the external mica surfaces, which are known to hydrate upon exposure to atmospheric moisture. These results demonstrate that modern pulsed NMR techniques and high fields can be used effectively to provide structural details of strontium binding by phyllosilicate minerals.

Bowers, Geoffrey M.; Ravella, Ramesh; Komarneni, S.; Mueller, Karl T.

2006-04-13

282

High-resolution NMR with resistive and hybrid magnets: deconvolution using a field-fluctuation signal.  

PubMed

A method for compensating effect of field fluctuation is examined to attain high-resolution NMR spectra with resistive and hybrid magnets. In this method, time dependence of electromotive force induced for a pickup coil attached near a sample is measured synchronously with acquisition of NMR. Observed voltage across the pickup coil is converted to field fluctuation data, which is used to deconvolute NMR signals. The feasibility of the method is studied by (79)Br MAS NMR of KBr under a 30T magnetic field of a hybrid magnet. Twenty single-scan NMR signals were accumulated after the manipulation, resulting in a high-resolution NMR spectrum. PMID:17123849

Iijima, Takahiro; Takegoshi, K; Hashi, Kenjiro; Fujito, Teruaki; Shimizu, Tadashi

2007-02-01

283

Automatic assignment of absolute configuration from 1D NMR data.  

PubMed

[reaction: see text] Opposite enantiomers exhibit different NMR properties in the presence of an external common chiral element, and a chiral molecule exhibits different NMR properties in the presence of external enantiomeric chiral elements. Automatic prediction of such differences, and comparison with experimental values, leads to the assignment of the absolute configuration. Here two cases are reported, one using a dataset of 80 chiral secondary alcohols esterified with (R)-MTPA and the corresponding (1)H NMR chemical shifts and the other with 94 (13)C NMR chemical shifts of chiral secondary alcohols in two enantiomeric chiral solvents. For the first application, counterpropagation neural networks were trained to predict the sign of the difference between chemical shifts of opposite stereoisomers. The neural networks were trained to process the chirality code of the alcohol as the input, and to give the NMR property as the output. In the second application, similar neural networks were employed, but the property to predict was the difference of chemical shifts in the two enantiomeric solvents. For independent test sets of 20 objects, 100% correct predictions were obtained in both applications concerning the sign of the chemical shifts differences. Additionally, with the second dataset, the difference of chemical shifts in the two enantiomeric solvents was quantitatively predicted, yielding r(2) 0.936 for the test set between the predicted and experimental values. PMID:15760195

Zhang, Qing-You; Carrera, Gonçalo; Gomes, Mário J S; Aires-de-Sousa, João

2005-03-18

284

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 ...

DeVience, Stephen J; 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

2014-01-01

285

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

286

Nuclear magnetic resonance (NMR)-based drug metabolite profiling.  

PubMed

The identification of drug metabolites in biofluids such as urine, plasma and bile is an important step in drug discovery and development. Proton nuclear magnetic resonance ((1)H-NMR) spectroscopy can provide detailed information regarding the structural transformation of a compound as a consequence of metabolism. However, successful identification of drug metabolites by (1)H-NMR spectroscopy is generally compromised by the presence of endogenous metabolites, which can obscure the signals of the drug metabolites in question. Hence, sample clean-up and separation of the metabolites from the biofluid matrix is crucial. This is generally achieved by extraction of the biofluid, solid-phase extraction (SPE), high-performance liquid chromatography (HPLC) or any combination of these. Apart from (1)H, other NMR-active nuclei, such as (19)F, can provide a useful handle for metabolite profiling, provided they are not naturally present in the biofluid. Successful studies have shown that the presence of a fluorine-handle on the drug and its metabolites can provide additional qualitative and quantitative data by (19)F-NMR spectroscopy. This chapter provides guidelines and examples of NMR-based drug metabolite profiling. PMID:21207298

Lenz, Eva M

2011-01-01

287

15N chemical shift referencing in solid state NMR.  

PubMed

Solid-state NMR spectroscopy has much advanced during the last decade and provides a multitude of data that can be used for high-resolution structure determination of biomolecules, polymers, inorganic compounds or macromolecules. In some cases the chemical shift referencing has become a limiting factor to the precision of the structure calculations and we have therefore evaluated a number of methods used in proton-decoupled (15)N solid-state NMR spectroscopy. For (13)C solid-state NMR spectroscopy adamantane is generally accepted as an external standard, but to calibrate the (15)N chemical shift scale several standards are in use. As a consequence the published chemical shift values exhibit considerable differences (up to 22 ppm). In this paper we report the (15)N chemical shift of several commonly used references compounds in order to allow for comparison and recalibration of published data and future work. We show that (15)NH4Cl in its powdered form (at 39.3 ppm with respect to liquid NH3) is a suitable external reference as it produces narrow lines when compared to other reference compounds and at the same time allows for the set-up of cross-polarization NMR experiments. The compound is suitable to calibrate magic angle spinning and static NMR experiments. Finally the temperature variation of (15)NH4Cl chemical shift is reported. PMID:24746715

Bertani, Philippe; Raya, Jésus; Bechinger, Burkhard

2014-01-01

288

Evaluation of abdominal aortic aneurysms with NMR imaging  

SciTech Connect

Seven patients (5 male and 2 female, age range from 50 to 88) with angiographic proven abdominal aortic aneurysms were evaluated with NMR imaging (1.5 K gauss system) of the abdomen. Images were obtained in transverse, coronal and saggital planes with three radiofrequency pulse sequences (saturation recovery (SR), inversion recovery (IR), and spin echo (SE)). All of the aneurysms were identified as to site and relative size with NMR images. The lumen in which there was flowing blood was always dark (low intensity), whereas the aneurysmal area which contained presumed clot was brighter (high intensity) on SR images. Although the size, location and relationship to other blood vessels was best demonstrated on aortography, NMR images provided similar information in all cases. NMR images correctly demonstrated thrombus in six cases. The authors conclude that NMR imaging provides a clear delineation of the anatomy of abdominal aortic aneurysms. In addition it can provide information concerning tissue type, i.e., it distinguished clot from moving blood. It may be possible in the future to further characterize atherosclerotic and other pathological changes in vessel architecture by using various pulse sequences and timing parameters to provide in vivo histological typing.

Evancho, A.; Osbakken, M.; Weidner, W.

1984-01-01

289

Condensed Matter NMR under Extreme Conditions: Challenges and Opportunities  

NASA Astrophysics Data System (ADS)

Advances in resistive magnet and power supply technology have made available extremely high magnetic fields suitable for condensed matter broadline NMR experiments. This capability expands the available phase space for investigating a wide variety of materials using magnetic resonance; utilizing the strength of the field to expose or induce new physical phenomena resulting in better understanding of the physics. Continuous fields up to 45T in NHMFL Hybrid magnet have brought new challenges in designing NMR instrumentation. Field strengths and sample space limitations put constraints on RF pulse power, tuning range, bandwidth, and temperature control. The inclusion of other capabilities, including high pressure, optics, and sample rotation requires intricate probe design and construction, while extremely low milliKelvin temperatures are desired in order to explore energy scales where thermal fluctuations are suppressed. Optimization of these devices has been of paramount consideration in NHMFL Condensed Matter NMR user program. Science achieved at high fields, the new initiatives to develop resistively-detected NMR in 2D electron gas and similar systems, and the current new generation Series-Connected Hybrid magnets for NMR work will be discussed. The NHMFL is supported by the National Science Foundation and the State of Florida.

Reyes, Arneil

2006-11-01

290

Characterization of amorphous material in shocked quartz by NMR spectroscopy  

SciTech Connect

Nuclear magnetic resonance (NMR) analysis of the recovered products from a series of controlled explosive shock-loading experiments on quartz powders was performed to investigate shock-induced amorphization processes. Silicon-29 NMR spectroscopy is an excellent probe of the local bonding environment of silicon in minerals and is capable of detecting and characterizing amorphous and disordered components. NMR spectra obtained for the recovered material exhibit a narrow resonance associated with the shocked crystalline material, and a broad component consistent with an amorphous phase despite the absence of evidence for glass from optical microscopy. The NMR measurements were performed over a range of recycle times from 1 to 3[times]10[sup 5] s. The results demonstrate that the magnetization in both the crystalline and amorphous material follows power-law behavior as a function of recycle time. The amorphous component dominates the spectra for short NMR recycle times due to its shorter relaxation time relative to the crystalline material. Fractal analysis of the power-law relations suggests a fractal dimension of 2 for the amorphous phase and 3 for the crystalline phase. [copyright] American Institute of Physics

Assink, R.A.; Boslough, M.B.; Cygan, R.T. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

1994-07-10

291

Characterization of amorphous material in shocked quartz by NMR spectroscopy  

SciTech Connect

Nuclear magnetic resonance (NMR) analysis of the recovered products from a series of controlled explosive shock-loading experiments on quartz powders was performed to investigate shock-induced amorphization processes. Silicon-29 NMR spectroscopy is an excellent probe of the local bonding environment of silicon in minerals and is capable of detecting and characterizing amorphous and disordered components. NMR spectra obtained for the recovered material exhibit a narrow resonance associated with the shocked crystalline material, and a broad component consistent with an amorphous phase despite the absence of evidence for glass from optical microscopy. The NMR measurements were performed over a range of recycle times from 1 to 3 {times} 10{sup 5} S. Results demonstrate that the magnetization in both the crystalline and amorphous material following power-law behavior as a function of recycle time. The amorphous component dominates the spectra for short NMR recycle times due to its shorter relaxation time relative to the crystalline material. Fractal analysis of the power-law relations suggests a fractal dimension of 2 for the amorphous phase and 3 for the crystalline phase.

Assink, R.A.; Boslough, M.B.; Cygan, R.T.

1993-08-01

292

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

293

NMR-based analysis of protein-ligand interactions.  

PubMed

Physiological processes are mainly controlled by intermolecular recognition mechanisms involving protein-protein and protein-ligand (low molecular weight molecules) interactions. One of the most important tools for probing these interactions is high-field solution nuclear magnetic resonance (NMR) through protein-observed and ligand-observed experiments, where the protein receptor or the organic compounds are selectively detected. NMR binding experiments rely on comparison of NMR parameters of the free and bound states of the molecules. Ligand-observed methods are not limited by the protein molecular size and therefore have great applicability for analysing protein-ligand interactions. The use of these NMR techniques has considerably expanded in recent years, both in chemical biology and in drug discovery. We review here three major ligand-observed NMR methods that depend on the nuclear Overhauser effect-transferred nuclear Overhauser effect spectroscopy, saturation transfer difference spectroscopy and water-ligand interactions observed via gradient spectroscopy experiments-with the aim of reporting recent developments and applications for the characterization of protein-ligand complexes, including affinity measurements and structural determination. PMID:23591643

Cala, Olivier; Guillière, Florence; Krimm, Isabelle

2014-02-01

294

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

295

Recovery of underwater resonances by magnetization transferred NMR spectroscopy (RECUR-NMR).  

PubMed

A method for detecting small molecule NMR resonances under a water peak in biological samples is presented. After high-efficiency solvent suppression using double WATERGATE, either a TOCSY- or ROESY-based coherence transfer sequence is applied to reestablish the resonances close to, or under, water through magnetization transfer using scalar or dipolar coupling, respectively. The use of the TOCSY and ROESY methods ensures an in-phase magnetization transfer, which makes the new approach readily extended for the measurement of transverse relaxation times, internuclear ROEs, and ROE buildup rates. An extension of the new approach for J-resolved spectroscopy is also presented and tested using a sample of human blood plasma. PMID:11700090

Liu, M; Tang, H; Nicholson, J K; Lindon, J C

2001-11-01

296

Recovery of Underwater Resonances by Magnetization Transferred NMR Spectroscopy (RECUR-NMR)  

NASA Astrophysics Data System (ADS)

A method for detecting small molecule NMR resonances under a water peak in biological samples is presented. After high-efficiency solvent suppression using double WATERGATE, either a TOCSY- or ROESY-based coherence transfer sequence is applied to reestablish the resonances close to, or under, water through magnetization transfer using scalar or dipolar coupling, respectively. The use of the TOCSY and ROESY methods ensures an in-phase magnetization transfer, which makes the new approach readily extended for the measurement of transverse relaxation times, internuclear ROEs, and ROE buildup rates. An extension of the new approach for J-resolved spectroscopy is also presented and tested using a sample of human blood plasma.

Liu, Maili; Tang, Huiru; Nicholson, Jeremy K.; Lindon, John C.

2001-11-01

297

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

298

Magnetic state of FeCl3 investigated by NMR  

NASA Astrophysics Data System (ADS)

The spin state of FeCl3 was measured by Nuclear Magnetic Resonance (NMR) as a function of temperature and magnetic field. The sublattice magnetization obtained from the 57Fe NMR spectrum fits well with the theoretical prediction for an antiferromagnet with a magnetic anisotropy field of less than 70 mT in the ab-plane. The field dependence of the 57Fe NMR spectrum shows that a spin rotation plane of helical order starts to align perpendicularly to the external field direction as the field increases from 0 and ends around 4 T with no phase transition. From the spin tilting angle analysis, we obtained the quantitative relation among the exchange coupling constants.

Kang, Byeongki; Kim, Changsoo; Jo, Euna; Kwon, Sangil; Lee, Soonchil

2014-06-01

299

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

300

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

301

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

302

Challenges in NMR instrumentation at high fields and low temperatures  

NASA Astrophysics Data System (ADS)

Advances in resistive magnet and power supply technology have made available high magnetic fields suitable for condensed matter (broad line) NMR experiments. This capability expands available phase space for investigating a variety of material behavior using magnetic resonance. This also presents new challenges in the design and construction of NMR instrumentation. Field strengths and sample space limitations put constraints on RF power, tank circuit tuning range, field homogeneity and stability, and temperature control.. NMR probes incorporating capabilities such as high pressures, high (>350K) and low (<1.5K) temperatures, optical pumping, and sample rotation require creative designs. Unique user facilities at NHMFL are described focusing probe and cryogenic designs that circumvented problems associated with the high field resistive magnets. Instrumentation developed for the new 45T hybrid magnet will also be presented.

Moulton, William; Reyes, Arneil; Kuhns, Phillip

2000-03-01

303

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

304

Paramagnetic shimming for wide-range variable-field NMR.  

PubMed

We propose a new passive shimming strategy for variable-field NMR experiments, in which the magnetic field produced by paramagnetic shim pieces placed inside the magnet bore compensates the inhomogeneity of a variable-field magnet for a wide range of magnet currents. Paramagnetic shimming is demonstrated in (7)Li, (87)Rb, and (45)Sc NMR of a liquid solution sample in magnetic fields of 3.4, 4.0, and 5.4T at a fixed carrier frequency of 56.0MHz. Since both the main-field inhomogeneity and the paramagnetic magnetization are proportional to the main-magnet current, the resonance lines are equally narrowed by the improved field homogeneity with an identical configuration of the paramagnetic shim pieces. Paramagnetic shimming presented in this work opens the possibility of high-resolution variable-field NMR experiments. PMID:25080372

Ichijo, Naoki; Takeda, Kazuyuki; Takegoshi, K

2014-09-01

305

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)...

306

Derivation of quantitative information in NMR imaging: a phantom study.  

PubMed

The use of NMR imaging as a quantitative research tool requires insight into the relationship between various imaging techniques and their resultant images. Work was undertaken to elucidate this relationship by using the following procedure. First, a theoretical model of NMR imaging under various pulse sequences was elaborated. Subsequently, a series of inversion recovery and saturation recovery images of a particular object slice was generated by varying the sequence parameters. Finally, pure rho, T1 and T2 images of that slice were obtained by solving the corresponding model equations. This procedure was applied to a test phantom containing tubes with suitable reference substances, including aqueous solutions of agar, manganese chloride and deuterium, and water-fat mixtures. The concentration of various samples was chosen such as to yield rho, T1 and T2 values usually encountered in clinical NMR imaging. Experiments were carried out with a prototype resistive NMR imager with a static magnetic field of 0.14 T, corresponding to a hydrogen proton resonance frequency of 5.9 MHz. For most samples a weighted non-linear regression analysis showed the theoretical model to produce an adequate parametrisation of the data at the 5% significance level, given the number of data points and the experimental accuracy. The quantitative information extracted from the NMR imaging experiments, i.e. rho, T1 and T2, appeared to be in good agreement with the results of conventional methods, including NMR spectroscopy. The clinical efficacy of the proposed methods is currently being investigated. PMID:6514785

Bakker, C J; de Graaf, C N; van Dijk, P

1984-12-01

307

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

308

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

309

Complete NMR characterization of lychnose from Stellaria media (L.) Vill.  

PubMed

Lychnose (alpha-D-Gal-(1-->6)-alpha-D-Glc-(1-->2)-beta-D-Fru-(1-->1)-alpha-D-Gal) was isolated from Stellaria media, a representative member of the Caryophyllaceae plant family. Weak acid hydrolysis, enzymatic hydrolysis and complete NMR characterization were performed to confirm the identity of the tetrasaccharide. All (1)H and (13)C resonances were unambiguously assigned and the conformation of the sugars was determined using one and two dimensional NMR techniques. Anomeric characterizations in lychnose were confirmed from HMBC and NOESY spectra. PMID:16997290

Vanhaecke, Mieke; Van den Ende, Wim; Van Laere, André; Herdewijn, Piet; Lescrinier, Eveline

2006-11-27

310

Advanced NMR approaches in the characterization of coal  

SciTech Connect

A considerable effort in this project during the past few months has been focussed on the development of [sup 1]H and [sup 13]C NMR imaging techniques to yield spatially-resolved chemical shift (structure) information on coal. In order to yield the chemical shift information, a solid-state NMR imaging technique must include magic-angle spinning, so rotating gradient capabilities are indicated. A [sup 13]C MAS imaging probe and a [sup 1]H MAS imaging probe and the circuitry necessary for rotating gradients have been designed and constructed. The [sup 1]H system has already produced promising preliminary results, which are briefly described in this report.

Maciel, G.E.

1992-01-01

311

NMR-based structural biology of proteins in supercooled water.  

PubMed

NMR-based structural biology of proteins can be pursued efficiently in supercooled water at temperatures well below the freezing point of water. This enables one to study protein structure, dynamics, hydration and cold denaturation in an unperturbed aqueous solution at very low temperatures. Furthermore, such studies enable one to accurately measure thermodynamic parameters associated with protein cold denaturation. Presently available approaches to acquire NMR data for supercooled aqueous protein solutions are surveyed, new insights obtained from such studies are summarized, and future perspectives are discussed. PMID:21533787

Szyperski, Thomas; Mills, Jeffrey L

2011-03-01

312

Inverse methods in two-dimensional NMR spectral analysis  

NASA Astrophysics Data System (ADS)

Solid-state NMR is a valuable technique for the study of disordered materials. Analysis of such spectra usually involves solution of so-called ill-posed inverse problems. Here we present a strategy for the analysis of two-parameter two-dimensional NMR problems and test it on 2D DECODER and DOQSY experiments. Using Monte Carlo tests, constraints are determined for the resolution and accuracy of the analysis for both experiments. The methods are finally applied to spectra of spider dragline silk, a heterogeneous solid fibrous protein.

van Beek, Jacco D.; Meier, Beat H.; Schäfer, Hartmut

2003-05-01

313

NMR spectroscopy of xenon sorbed in pentasil zeolites: Silicalites  

SciTech Connect

{sup 129}Xe NMR spectroscopy of xenon sorbed in silicalite samples shows a complex line shape. The authors conclude that there are at least two regions in these samples, one of which is a macroscopic region free of occlusions and the other is a region (or regions) containing occlusions. The authors suggest that these occlusions are residual template molecules from the preparation of the material. Analysis of commercial preparations of silicalite and one prepared in this laboratory indicates that xenon NMR spectroscopy is a simple, straightforward means of examining residual template or other macroscopic occlusions in similar microporous materials.

Tsiao, Chihji; Dybowski, C. (Univ. of Delaware, Newark (USA)); Corbin, D.R. (E.I. du Pont de Nemours and Co., Inc., Wilmington, DE (USA)); Durante, V.; Walker, D. (Sun Refining and Marketing Co., Marcus Hook, PA (USA))

1990-05-17

314

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

315

Analysis of cement/waste mixtures with solid-state NMR spectroscopy  

SciTech Connect

We have used solid-state {sup 2}H and {sup 13}C NMR spectroscopy to study the interaction of phenol with portland cement as a function of cure, loading, and hydration. The {sup 2}H NMR of deuterated phenol is used to follow the microscopic dynamics of a phenoxide ion: typically half of the phenoxide ions are freely mobile and half undergo restricted motion, which indicates bonding to the cement matrix. The {sup 13}C NMR, both CP/MAS sideband analysis and static hole-burning NMR, is consistent with this analysis. A new low-temperature, 18 Tesla field-swept NMR has been used to obtain {sup 27}Al NMR resonances that are otherwise difficult to obtain with conventional NMR methods, unfortunately, the resonance is rather featureless at 4.2 K, thus indicating a critical need for VT field-swept NMR.

Cartledge, F.K.; Butler, L.G. [Louisiana State Univ., Baton Rouge, LA (United States)

1995-12-31

316

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

317

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

318

NMR-detected hydrogen exchange and molecular dynamics simulations provide structural insight into  

E-print Network

NMR-detected hydrogen exchange and molecular dynamics simulations provide structural insight Research, National Institute for Physiological Sciences, 38 Nishigonaka Myodaiji, Okazaki, Aichi 444 electron microscopy, CD spectroscopy, NMR-detected hydrogen­deuterium exchange mea- surements

Roder, Heinrich

319

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

320

Superconducting Magnet Safety Nuclear Magnetic Resonance (NMR) facilities present unique hazards not found in most  

E-print Network

Superconducting Magnet Safety Nuclear Magnetic Resonance (NMR) facilities present unique hazards not found in most laboratory environments. The NMR facilities maintain superconducting magnets which have associated with installation and operation. Temperature, structural support and magnetic field isolation

Maroncelli, Mark

321

LC-NMR Technique in the Analysis of Phytosterols in Natural Extracts  

PubMed Central

The ability of LC-NMR to detect simultaneously free and conjugated phytosterols in natural extracts was tested. The advantages and disadvantages of a gradient HPLC-NMR method were compared to the fast composition screening using SEC-NMR method. Fractions of free and conjugated phytosterols were isolated and analyzed by isocratic HPLC-NMR methods. The results of qualitative and quantitative analyses were in a good agreement with the literature data. PMID:24455424

Horník, Št?pán; Sajfrtová, Marie; Sýkora, Jan; B?ezinová, Anna; Wimmer, Zden?k

2013-01-01

322

Negative Mood Regulation (NMR) expectancies, mood, and affect intensity among clients in substance disorder treatment facilities  

Microsoft Academic Search

Negative mood regulation (NMR) expectancies, stress, anxiety, depression and affect intensity were examined by means of self-report questionnaires in 158 volunteers, including 99 clients enrolled in addiction treatment programs. As expected, addicts reported significantly higher levels of stress, anxiety, depression and affect intensity and lower levels of NMR compared to non-addict controls. NMR was negatively correlated with stress, anxiety, depression

Fred Arne Thorberg; Michael Lyvers

2006-01-01

323

Visualization of cerebral and vascular abnormalities by NMR imaging. The effects of imaging parameters on contrast  

SciTech Connect

The relationship between data acquisition parameters and contrast in nuclear magnetic resonance (NMR) images was studied. NMR imaging by the pulse echo technique selectively enhanced intracranial abnormalities; imaging by the inversion recovery technique heightened the difference between cerebral gray and white matter. Using a blood flow model, the authors also showed that NMR imaging of flow in major vessels is possible.

Crooks, L.E. (Univ. of California, San Francisco); Mills, C.M.; Davis, P.L.; Brant-Zawadzki, M.; Hoenninger, J.; Arakawa, M.; Watts, J.; Kaufman, L.

1982-09-01

324

Nanoscale NMR Spectroscopy and Imaging of Multiple Nuclear Stephen J. DeVience,1,  

E-print Network

Nanoscale NMR Spectroscopy and Imaging of Multiple Nuclear Species Stephen J. DeVience,1, Linh M nanoscale NMR spectroscopy and imaging under ambient conditions of samples containing multiple nuclear (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple

Walsworth, Ronald L.

325

NMR T1-Relaxation Measurements on Paramagnetic Organolanthanides: an Alternative Tool for Structure Determination  

E-print Network

NMR T1-Relaxation Measurements on Paramagnetic Organolanthanides: an Alternative Tool for Structure-lattice relaxation times / paramagnetic complexes / lanthanides / 1 H NMR 1 H NMR investigations were conducted on four paramagnetic organolanthanides all bearing the tetraisopropylcyclopentadienyl Cp4i ligand (Cp4i

Paris-Sud XI, Université de

326

Immobilization and chelation of metal complexes with bifunctional phosphine ligands: a solid-state NMR study  

E-print Network

.5747 Garching, Germany 29Si CP MAS NMR shows that a transition-metalcomplex with two bifunctional phosphine or an addition reaction to surface siloxane groups takes place.'3 This can be seen in the 29Si CP MAS NMR-state NMR study Klaus D. Behringer and Janet Blumel" Anorganisch-chemisches Institut der TU Miinchen, 8

Bluemel, Janet

327

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

328

NMR water mobility in xanthan and locust bean gum mixtures: possible explanation of microbial response  

Microsoft Academic Search

Molecular and structural mobility of xanthan and locust bean gum mixtures (with and without mannitol) were studied in relation to microbial stability. Molecular mobility was measured by solid state 1H and 2H NMR and by 2H high resolution NMR while differential scanning calorimetry and dynamic mechanical analysis were used to investigate structural mobility. The NMR mobile signal was found to

E. Vittadini; L. C. Dickinson; P. Chinachoti

2002-01-01

329

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

330

High temperature 17O MAS NMR study of calcia, magnesia, scandia and yttria stabilized zirconia  

Microsoft Academic Search

High-resolution 17O MAS NMR can provide unique constraints on local structure and oxide ion dynamics in conductive zirconia ceramics of interest for fuel cells and other technologies. We describe here NMR and bulk conductivity measurements for scandia, yttria, calcia, and magnesia stabilized zirconias, including MAS NMR spectra collected in situ at temperatures up to 700 °C. All of the cubic compounds

Namjun Kim; Cheng-Han Hsieh; Hong Huang; Fritz B. Prinz; Jonathan F. Stebbins

2007-01-01

331

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

332

Communication Ultrafast 2D NMR spectroscopy using a continuous spatial encoding of the spin interactions  

Microsoft Academic Search

A new protocol for acquiring multidimensional NMR spectra within a single scan is introduced and illustrated. The approach relies on applying a pair of frequency-chirped excitation and storage pulses in combination with echoing magnetic field gradients, in order to impart the kind of linear spatial encoding of the NMR interactions that is required by ultrafast 2D NMR spectroscopy. It is

Yoav Shrot; Boaz Shapira; Lucio Frydman

333

Characterization of the Aspergillus nidulans nmrA Gene Involved in Nitrogen Metabolite Repression  

PubMed Central

The gene nmrA of Aspergillus nidulans has been isolated and found to be a homolog of the Neurospora crassa gene nmr-1, involved in nitrogen metabolite repression. Deletion of nmrA results in partial derepression of activities subject to nitrogen repression similar to phenotypes observed for certain mutations in the positively acting areA gene. PMID:9537404

Andrianopoulos, Alex; Kourambas, Sophie; Sharp, Julie A.; Davis, Meryl A.; Hynes, Michael J.

1998-01-01

334

Detection of NMR signals with a radio-frequency atomic magnetometer I.M. Savukov 1  

E-print Network

Detection of NMR signals with a radio-frequency atomic magnetometer I.M. Savukov 1 , S.J. Seltzer of proton NMR signals with a radio-frequency (rf) atomic magnetometer tuned to the NMR frequency of 62 kHz. High-frequency operation of the atomic magnetometer makes it relatively insensitive to ambient magnetic

Romalis, Mike

335

Updating NMR Probe Electronics in the Muon g-2 Experiment  

E-print Network

Updating NMR Probe Electronics in the Muon g-2 Experiment AUDREY KVAM University of Washington, 2014 INT REU The intent of the Muon g-2 experiment is to test the completeness of the Standard Model by measuring with extreme precision the anomalous magnetic moment aµ 1 2 (g - 2) of the muon and comparing

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

336

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

337

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

338

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.

339

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

340

Enhanced protein fold recognition using secondary structure information from nmr  

Microsoft Academic Search

NMR offers the possibility of accurate secondary structure for proteins that would be too large for structure determi- nation. In the absence of an X-ray crystal structure, this information should be useful as an adjunct to protein fold recognition methods based on low resolution force fields. The value of this information has been tested by adding varying amounts of artificial

Daniel J. Ayers; Paul R. Gooley; Asaph Widmer-Cooper; Andrew E. Torda

1999-01-01

341

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;); Philip J Hajduk (Abbott Laboratories;); Robert Meadows (Abbott Laboratories;); Stephen Fesik (Abbott Laboratories;)

1996-11-29

342

A SR AND NMR STUDY OF QUANTUM TUNNELING OF THE  

E-print Network

Family of High Spin Molecules . . . . . . . . . . . . . . . . . . 11 1.2.1 Chemical Synthesis of the HSM Nuclear Spin and Dipolar Interaction . . . . . . . . . . . . 19 2.5 Landau-Zenner Tunneling . . . . . . . . . 36 3.3 The Nuclear Magnetic Resonance (NMR) Technique . . . . . . . . . 40 3.3.1 Experimental Setup

Keren, Amit

343

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

344

1H NMR analysis of sporopollenin from Typha Angustifolia  

Microsoft Academic Search

The first analysis of sporopollenin using 1H NMR-techniques revealed the presence of four phenolic compounds in different amounts. The phenolic compounds are tri- or tetrasubstituted. The sporopollenin was isolated and purified from Typha angustifolia by an enzymatic procedure, followed by extraction with organic solvents.

Friedhelm Ahlers; Ina Thom; Jörg Lambert; Rüdiger Kuckuk; Rolf Wiermann

1999-01-01

345

Journal of Biomolecular NMR, 25: 281290, 2003. KLUWER/ESCOM  

E-print Network

December 2002 Key words: biological macromolecule, chemical shift, chemical shift-coded experiment, multi-dimensional for chemical shift monitoring in a multi-dimensional NMR experiment. The monitored chemical shift is coded-optimized spectroscopy; 2D, 3D, 4D ­ two-dimensional, three-dimensional, four-dimensional. Introduction Multi-dimensional

Riek, Roland

346

Ligand-target interactions: what can we learn from NMR?  

PubMed

The conformation of the ligand in complex with a macromolecular target can be studied by nuclear magnetic resonance (NMR) in solution for both tightly and weakly forming complexes. In the weak binding regime (k(off) > 10(4) Hz), the structure of the bound ligand is accessible also for very large complexes (>100 kDa), which are not amenable to NMR studies in the tight binding regime. Here I review the state-of-the-art NMR methodology used for screening ligands and for the structural investigation of bound ligand conformations, in both tight and weak binding regimes. The advantages and disadvantages of each approach are critically described. The NMR methodology used to investigate transiently forming complexes has expanded considerably in the past few years, opening new possibilities for a detailed description of ligand-target interactions. Novel methods for the determination of the bound ligand conformation, in particular transferred cross-correlated relaxation, are thoroughly reviewed, and their advantages with respect to established methodology are discussed, using the epothilone-tubulin complex as a primary example. PMID:15869390

Carlomagno, Teresa

2005-01-01

347

Signal identification in NMR spectra with coupled evolution periods  

Microsoft Academic Search

Novel multidimensional NMR experiments rely on modified time-domain sampling schemes to provide significant savings of experimental time. Several approaches are based on the coupling of evolution times resulting in a reduction of the dimensionality of the recorded spectra, and a concomitant saving of experimental time. We present a consistent and general tool, called EVOCOUP, for the analysis of these reduced

Daniel Malmodin; Martin Billeter

2005-01-01

348

Fluid-Rock Characterization and Interactions in NMR Well Logging  

Microsoft Academic Search

The objective of this project is to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. This is the first annual progress report submitted to the DOE. It reports on the work completed during the reporting period even if it may have started before this period. This project is a partnership between

George J. Hirasaki; Kishore K. Mohanty; K. Kishore

2001-01-01

349

Polar Fourier transforms of radially sampled NMR data  

Microsoft Academic Search

Radial sampling of the NMR time domain has recently been introduced to speed up data collection significantly. Here, we show that radially sampled data can be processed directly using Fourier transforms in polar coordinates. We present a comprehensive theoretical analysis of the discrete polar Fourier transform, and derive the consequences of its application to radially sampled data using linear response

Brian E. Coggins; Pei Zhou

2006-01-01

350

NMR at the Picomole Level of a DNA Adduct  

PubMed Central

We investigate the limit of detection for obtaining NMR data of a DNA adduct using modern microscale NMR instrumentation, once the adduct has been isolated at the pmol level. Eighty nanograms (130 pmol) of a DNA adduct standard, N-(2?-deoxyguanosin-8-yl)-2-acetylaminofluorene 5?-monophosphate (AAF-dGMP), in 1.5 ?L of D2O with 10% methanol-d4, in a vial, was completely picked up as a droplet suspended in a fluorocarbon liquid, and loaded efficiently into a microcoil probe. This work demonstrates a practical manual method of droplet microfluidic sample loading, previously demonstrated using automated equipment, which provides a several-fold advantage over conventional flow injection. Eliminating dilution during injection and confining the sample into the observed volume realizes the full theoretical mass sensitivity of a microcoil, comparable to a micro-cryo probe. With 80 ng, an NMR spectrum acquired over 40 hr showed all of the resonances seen in a standard spectrum of AAF-dGMP, with a S/N of at least 10, despite broadening due to previously-noted effects of conformational exchange. Also a 2D TOCSY spectrum (total correlation spectroscopy) was acquired on 1.6 ?g in 18 hr. This work helps to define the utility of NMR in combination with other analytical methods for the structural characterization of a small amount of a DNA adduct. PMID:24028148

Kautz, Roger; Wang, Poguang; Giese, Roger W.

2014-01-01

351

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

352

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

353

Two-dimensional NMR spectroscopy with temperature-sweep.  

PubMed

Two-dimensional nuclear magnetic resonance (NMR) spectroscopy is useful for studying temperature-dependent effects on molecular structure. However, experimental time is usually long, because sampling is repeated at several temperatures. A novel solution to the problem is proposed, in which signal sampling is performed in parallel to the linear temperature-sweep. PMID:24863674

Bermel, Wolfgang; Dass, Rupashree; Neidig, Klaus-Peter; Kazimierczuk, Krzysztof

2014-08-01

354

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

355

A Networked NMR Spectrometer: Configuring a Shared Instrument  

ERIC Educational Resources Information Center

A model for a shared nuclear magnetic resonance spectroscopy (NMR) facility between a private university and two local community colleges is presented. The discussion of the components required for the shared facility, modes of data distribution, and overall effect on the curriculum is presented.

Alonso, David; Mutch, G. William; Wong, Peter; Warren, Steven; Barot, Bal; Kosinski, Jan; Sinton, Mark

2005-01-01

356

Determination of Membrane Protein Structure by Rotational Resonance NMR: Bacteriorhodopsin  

Microsoft Academic Search

Rotationally resonant magnetization exchange, a new nuclear magnetic resonance (NMR) technique for measuring internuclear distances between like spins in solids, was used to determine the distance between the C-8 and C-18 carbons of retinal in two model compounds and in the membrane protein bacteriorhodopsin. Magnetization transfer between inequivalent spins with an isotropic shift separation, delta, is driven by magic angle

F. Creuzet; A. McDermott; R. Gebhard; K. van der Hoef; M. B. Spijker-Assink; J. Herzfeld; J. Lugtenburg; M. H. Levitt; R. G. Griffin

1991-01-01

357

NMR Evidence for psuedogap in URu2Si2  

NASA Astrophysics Data System (ADS)

We report ^29Si NMR measurements in single crystals and aligned powders of URu2Si2 in the hidden order and paramagnetic phases. In the paramagnetic phase, the spin lattice relaxation data reveal evidence of spin fluctuations of U moments. Furthermore, we find evidence for partial suppression of density of states below 30 K.

Shirer, Kent; Dioguardi, Adam; Crocker, John; Aproberts-Warren, Nicholas; Shockley, Abigail; Lin, Ching; Nisson, David; Cooley, Jason; Maple, Brian; Haraldsen, Jason; Graf, Matthias; Curro, Nicholas

2013-03-01

358

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

359

Radiation Damping for Speeding-up NMR Applications  

E-print Network

We demonstrate theoretically and numerically how to control the NMR relaxation rate after application of the standard spin echo technique. Using radiation damping, we return the nuclear magnetization to its equilibrium state during a time interval that is negligible compared to the relaxation time. We obtain an estimate for optimal radiation damping which is consistent with our numerical simulations.

Berman, Gennady P; Gorshkov, Vyacheslav N; Tsifrinovich, Vladimir I; Volegov, Petr L

2011-01-01

360

Radiation Damping for Speeding-up NMR Applications  

E-print Network

We demonstrate theoretically and numerically how to control the NMR relaxation rate after application of the standard spin echo technique. Using radiation damping, we return the nuclear magnetization to its equilibrium state during a time interval that is negligible compared to the relaxation time. We obtain an estimate for optimal radiation damping which is consistent with our numerical simulations.

Gennady P. Berman; Michelle A. Espy; Vyacheslav N. Gorshkov; Vladimir I. Tsifrinovich; Petr L. Volegov

2011-11-25

361

NMR solution structure of the human prion protein  

Microsoft Academic Search

The NMR structures of the recombinant human prion protein, hPrP(23-230), and two C-terminal fragments, hPrP(90-230) and hPrP(121-230), include a globular domain extending from residues 125-228, for which a detailed structure was obtained, and an N-terminal flexibly disordered \\

Ralph Zahn; Aizhuo Liu; Thorsten Lührs; Roland Riek; Christine von Schroetter; Francisco López García; Martin Billeter; Luigi Calzolai; Gerhard Wider; Kurt Wüthrich

2000-01-01

362

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...

363

NMR CAT scanner: a new look at the brain  

Microsoft Academic Search

Thin-section transverse axial scans of the healthy human brain have been produced by nuclear magnetic resonance, and these are of sufficient quality to be compared to X-ray CAT scans of the same sections. Not unexpectedly, there are marked differences in the contrast shown by various structures within the brain. It seems even at this early stage that NMR CAT scanning

W. S. Moore; G. N. Holland; L. Kreel

1980-01-01

364

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

365

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

366

UNCORRECTED 2 Random-walk technique for simulating NMR measurements  

E-print Network

scales can be connected and, therefore, that 46the estimated values of S/V could be interpreted response of fluids in porous media. Simulations reproduce the effects of dif- 12 fusion within external 13 or permeable boundaries. The simulation approach consolidates existing NMR numerical methods used

Torres-Verdín, Carlos

367

Journal of Biomolecular NMR, 14: 7174, 1999. KLUWER/ESCOM  

E-print Network

of the amino acid products of the citric acid cycle. The selectivity and extensiveness of labeling precursors, result in relatively extensive la- beling of the amino acids produced from the citric acid cycle assignment, solid-state NMR Abstract The selective and extensive 13C labeling of mostly hydrophobicamino acid

Hong, Mei

368

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

369

Optimized linear prediction for radial sampled multidimensional NMR experiments  

Microsoft Academic Search

Radial sampling in multidimensional NMR experiments offers greatly decreased acquisition times while also providing an avenue for increased sensitivity. Digital resolution remains a concern and depends strongly upon the extent of sampling of individual radial angles. Truncated time domain data leads to spurious peaks (artifacts) upon FT and 2D FT. Linear prediction is commonly employed to improve resolution in Cartesian

John M. Gledhill; Vignesh Kasinath; A. Joshua Wand

2011-01-01

370

Rheo-NMR of shear banded flow in wormlike micelles  

NASA Astrophysics Data System (ADS)

Rheo-NMR gives access to detailed information about the flow field generated by the device used to induce deformational flow. It also provides information about colloidal or molecular organisation and dynamics, under conditions of flow. In particular, NMR offers the possibility of measuring nuclear spin relaxation times and molecular self-diffusion coefficients, sensitive respectively to molecular brownian motions and their restrictions due to local structure. Furthermore, through the use of orientation-dependent terms in the spin interactions, such as the nuclear quadrupole or dipolar interactions, NMR permits the measurement of molecular order parameters. When combined with imaging methods, NMR in principle allows such measurements to be spatially localized, often with resolution down to a few 10s of microns In the study of shear banding phenomena in wormlike micelles, Rheo-NMR has proven of especial value, not only indicating the clear existence of shear bands, but also that they are associated with fluctuations, and sometimes, with molecular alignment. The subtlety of the correspondence (or lack of correspondence) between birefringence effects and shear banded flow has also been revealed. Recent measurements of shear-banded flow under Couette flow of the micellar system 10% w/v cetylpyridinium chloride and sodium salicylate (CPyCl/NaSal) molar ratio 2:1 in 0.5 M NaCl in ^1H2O, indicate that shear banding fluctuations are consistent with the shear stress fluctuations observed in rheological measurements. Furthermore we find a coupling between flow fluctuations in the gradient and vorticity directions. Using ^2H NMR spectroscopy on a deuterated probe molecule (n-decane) in the wormlike micellar interior, direct measurement of the shear-induced nematic phase transition is reported. More recently we have used Rheo-NMR to investigate the flow and alignment properties of worm-like micelles formed by a 5% w/w solution of the BASF difunctional block copolymer non-ionic surfactant, Pluronic P105 in water along with 4.3% w/v 1-phenylethanol-d5. A variety of shear-banding and alignment behaviours are observed, along with both stable and fluctuating flows.

Callaghan, Paul

2008-03-01

371

“CLASSIC NMR”: An In-Situ NMR Strategy for Mapping the Time-Evolution of Crystallization Processes by Combined Liquid-State and Solid-State Measurements**  

PubMed Central

A new in-situ NMR strategy (termed CLASSIC NMR) for mapping the evolution of crystallization processes is reported, involving simultaneous measurement of both liquid-state and solid-state NMR spectra as a function of time. This combined strategy allows complementary information to be obtained on the evolution of both the solid and liquid phases during the crystallization process. In particular, as crystallization proceeds (monitored by solid-state NMR), the solution state becomes more dilute, leading to changes in solution-state speciation and the modes of molecular aggregation in solution, which are monitored by liquid-state NMR. The CLASSIC NMR experiment is applied here to yield new insights into the crystallization of m-aminobenzoic acid. PMID:25044662

Hughes, Colan E; Williams, P Andrew; Harris, Kenneth D M

2014-01-01

372

Two Phase Flow Measurements by Nuclear Magnetic Resonance (NMR)  

SciTech Connect

In concentrated suspensions, there is a tendency for the solid phase to migrate from regions of high shear rate to regions of low shear (Leighton & Acrivos, 1987). In the early years that our effort was funded by the DOE Division of Basic Energy Science, quantitative measurement of this process in neutrally buoyant suspensions was a major focus (Abbott, et al., 1991; Altobelli, et al., 1991). Much of this work was used to improve multi-phase numerical models at Sandia National Laboratories. Later, our collaborators at Sandia and the University of New Mexico incorporated body forces into their numerical models of suspension flow (Rao, Mondy, Sun, et al., 2002). We developed experiments that allow us to study flows driven by buoyancy, to characterize these flows in well-known and useful engineering terms (Altobelli and Mondy, 2002) and to begin to explore the less well-understood area of flows with multiple solid phases (Beyea, Altobelli, et al., 2003). We also studied flows that combine the effects of shear and buoyancy, and flows of suspensions made from non-Newtonian liquids (Rao, Mondy, Baer, et al, 2002). We were able to demonstrate the usefulness of proton NMR imaging of liquid phase concentration and velocity and produced quantitative data not obtainable by other methods. Fluids flowing through porous solids are important in geophysics and in chemical processing. NMR techniques have been widely used to study liquid flow in porous media. We pioneered the extension of these studies to gas flows (Koptyug, et al, 2000, 2000, 2001, 2002). This extension allows us to investigate a wider range of Peclet numbers, and to gather data on problems of interest in catalysis. We devised two kinds of NMR experiments for three-phase systems. Both experiments employ two NMR visible phases and one phase that gives no NMR signal. The earlier method depends on the two visible phases differing in a NMR relaxation property. The second method (Beyea, Altobelli, et al., 2003) uses two different nuclei, protons and 19F. It also uses two different types of NMR image formation, a conventional spin-echo and a single-point method. The single-point method is notable for being useful for imaging materials which are much more rigid than can usually be studied by NMR imaging. We use it to image “low density” polyethylene (LDPE) plastic in this application. We have reduced the imaging time for this three-phase imaging method to less than 10 s per pair of profiles by using new hardware. Directly measuring the solid LDPE signal was a novel feature for multi-phase flow studies. We also used thermally polarized gas NMR (as opposed to hyper-polarized gas) which produces low signal to noise ratios because gas densities are on the order of 1000 times smaller than liquid densities. However since we used multi-atom molecules that have short T1's and operated at elevated pressures we could overcome some of the losses. Thermally polarized gases have advantages over hyperpolarized gases in the ease of preparation, and in maintaining a well-defined polarization. In these studies (Codd and Altobelli, 2003), we used stimulated echo sequences to successfully obtain propagators of gas in bead packs out to observation times of 300 ms. Zarraga, et al. (2000) used laser-sheet profilometry to investigate normal stress differences in concentrated suspensions. Recently we developed an NMR imaging analog for comparison with numerical work that is being performed by Rekha Rao at Sandia National Laboratories (Rao, Mondy, Sun, et al, 2002). A neutrally buoyant suspension of 100 mm PMMA spheres in a Newtonian liquid was sheared in a vertical Couette apparatus inside the magnet. The outer cylinder rotates and the inner cylinder is fixed. At these low rotation rates, the free-surface of the Newtonian liquid shows no measurable deformation, but the suspension clearly shows its non-Newtonian character.

Altobelli, Stephen A; Fukushima, Eiichi

2006-08-14

373

Solid State NMR Studies of Energy Conversion and Storage Materials  

NASA Astrophysics Data System (ADS)

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

Jankuru Hennadige, Sohan Roshel De Silva

374

19F-NMR Studies of ?-Synuclein Conformation and Fibrillation†  

PubMed Central

Fibrils of the intrinsically-disordered protein ?-synuclein are hallmarks of Parkinson's disease. The fluorescent dye thioflavin T is often used to characterize fibrillation, but this assay may not provide quantitative information about structure and mechanism. To gain such information, we incorporated the 19F-labeled amino acid, 3-fluorotyrosine, into recombinant human ?-synuclein at its endogenous tyrosine residues. Tyrosine 39 is in the positively-charged N-terminal region of this 140-residue protein. The other three, tyrosines, 125, 133, and 136, are near the C-terminus. 19F-nuclear magnetic resonance spectroscopy was used to study several properties of labeled ?-synuclein, including its conformation; conformational changes induced by urea, spermine, and sodium dodecyl sulfate (SDS); its interaction with SDS micelles; and the kinetics of fibril formation. The results show that the tyrosines are in disordered regions but that there is some structure near position 39 that is disrupted by urea. SDS binding alters the conformation near position 39, but the C-terminal tyrosines are disordered under all conditions. The NMR data also indicate that SDS-micelle bound ?-synuclein and the free protein exchange on the 10-ms time scale. Studies of fibrillation show the utility of 19F-labeled NMR. The data indicate that fibrillation is not accompanied by the formation of large quantities of low molecular-weight intermediates. Although dye-binding and 19F NMR data show that 1-mM SDS and 1-mM spermine accelerate aggregation compared to buffer alone, only the NMR data indicate that the species formed in SDS are smaller than those formed in buffer or buffer plus spermine. We conclude that 19F NMR spectroscopy is useful for obtaining residue-level, quantitative information about the structure, binding, and aggregation of ?-synuclein. PMID:19655784

Li, Conggang; Lutz, Evan A.; Slade, Kristin M.; Ruf, Rebecca A.S.; Wang, Gui-Fang; Pielak, Gary J.

2009-01-01

375

Overhauser Dynamic Nuclear Polarization-Enhanced NMR Relaxometry  

PubMed Central

We present a new methodological basis for selectively illuminating a dilute population of fluid within a porous medium. Specifically, transport in porous materials can be analyzed by now-standard nuclear magnetic resonance (NMR) relaxometry and NMR pulsed field gradient (PFG) diffusometry methods in combination with with the prominent NMR signal amplification tool, dynamic nuclear polarization (DNP). The key components of the approach introduced here are (1) to selectively place intrinsic or extrinsic paramagnetic probes at the site or local volume of interest within the sample, (2) to amplify the signal from the local solvent around the paramagnetic probes with Overhauser DNP, which is performed in situ and under ambient conditions, and (3) to observe the ODNP-enhanced solvent signal with 1D or 2D NMR relaxometry methods, thus selectively amplifying only the relaxation dynamics of the fluid that resides in or percolates through the local porous volume that contains the paramagnetic probe. Here, we demonstrate the proof of principle of this approach by selectively amplifying the NMR signal of only one solvent population, which is in contact with a paramagnetic probe and occluded from a second solvent population. An apparent one-component T2 relaxation decay is shown to actually contain two distinct solvent populations. The approach outlined here should be universally applicable to a wide range of other 1D and 2D relaxometry and PFG diffusometry measurements, including T1–T2 or T1-D correlation maps, where the occluded population containing the paramagnetic probes can be selectively amplified for its enhanced characterization. PMID:23837010

Franck, John M.; Kausik, Ravinath; Han, Songi

2013-01-01

376

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

377

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

378

Sensitization of a stray-field NMR to vibrations: A potential for MR elastometry with a portable NMR sensor  

NASA Astrophysics Data System (ADS)

An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an "effective" square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR.

Mastikhin, Igor; Barnhill, Marie

2014-11-01

379

Sensitization of a stray-field NMR to vibrations: a potential for MR elastometry with a portable NMR sensor.  

PubMed

An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an "effective" square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR. PMID:25282441

Mastikhin, Igor; Barnhill, Marie

2014-11-01

380

1H-NMR and Hyperpolarized 13C-NMR Assays of Pyruvate-Lactate Exhange: a comparative study  

PubMed Central

Pyruvate-lactate exchange is mediated by the enzyme lactate dehydrogenase (LDH) and is central to the altered energy metabolism in cancer cells. Measurement of exchange kinetics using hyperpolarized 13C NMR has provided a biomarker of response to novel therapeutics. In this study we investigated an alternative in vitro 1H assay, using [3-13C]pyruvate, and compared the measured kinetics with a hyperpolarized 13C-NMR assay, using [1-13C]pyruvate, under the same conditions in human colorectal carcinoma SW1222 cells. The apparent forward reaction rate constants (kPL) derived from the two assays showed no significant difference, and both assays had similar reproducibility (kPL = 0.506 ± 0.054 and kPL = 0.441 ± 0.090 nmol/s/106 cells, (mean ± standard deviation, n = 3); 1H, 13C assays respectively). The apparent backward reaction rate constant (kLP) could only be measured with good reproducibility using the 1H-NMR assay (kLP = 0.376 ± 0.091 nmol/s/106 cells, (mean ± standard deviation, n = 3)). The 1H-NMR assay has adequate sensitivity to measure real-time pyruvate-lactate exchange kinetics in vitro, offering a complementary and accessible assay of apparent LDH activity. PMID:23712817

Orton, Matthew R.; Tardif, Nicolas; Parkes, Harold G.; Robinson, Simon P.; Leach, Martin O.; Chung, Yuen-Li; Eykyn, Thomas R.

2015-01-01

381

Random-walk technique for simulating NMR measurements and 2D NMR maps of porous media with relaxing and  

E-print Network

, therefore, that the estimated values of S/V could be interpreted in an aver- age sense in the presence in porous media. Simulations reproduce the effects of dif- fusion within external inhomogeneous background boundaries. The simulation approach consolidates existing NMR numerical methods used in biology

Torres-Verdín, Carlos

382

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

383

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

384

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

385

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

386

Immobilization of Carbonylnickel Complexes: A Solid-State NMR Study K. D. Behringer and J. Blu1mel*  

E-print Network

oxidation or cross-linking, and therefore narrow NMR lines, and it allows 13C CP/MAS NMR spectroscopy. 1Immobilization of Carbonylnickel Complexes: A Solid-State NMR Study K. D. Behringer and J. Blu1mel- and tricarbonylnickel complexes of these ligands are synthesized, characterized by 61Ni, 31P, 13C, and 1H NMR and IR

Bluemel, Janet

387

Applications of NMR to the dynamics of carbohydrates; simplifying NMR spectra of proteins  

SciTech Connect

Broadline /sup 1/H and high resolution /sup 13/C solid state nuclear magnetic resonance investigations of the dynamics of ..cap alpha.. and ..beta.. cyclodextrins, dextran, and their deuterated analogues in powders are reported. Qualitative spectral density functions are obtained for the kHz range motions from T/sub 1 rho/, T/sub 1d/, and T/sub 2/ mesurements. Faster motions were sampled with frequency dependence studies of T/sub 1/. From the relative proportions of the relaxation decays and lineshapes, it was possible to correlate these relaxation parameters with different segments of the molecules. Temperature dependence studies of T/sub 1/, T/sub 1d/ and the lineshape yielded some energies of activation and a correlation time for relaxation processes in ..cap alpha.. cyclodextrin. The results of these and other spin dynamics experiments are discussed in light of x-ray crystal and molecular structures. A new approach is proposed for the analysis of chemical shift data of proteins obtained from two-dimensional NMR experiments. Rather than studying the individual shifts of different atoms in a protein, statistical methods are applied to analyze the collection of chemical shifts of the whole molecule. Distribution functions for the spacing between nearest-neighbor energy levels are presented in the context of random matrix theory. The distribution of energy levels as a function of energy is characterized by a power law dependence. Randomness in a sequence of eigenvalues is also discussed. These methods reduce and classify the large data base of chemical shifts in proteins, which simplify the information content of their spectra. 75 references, 29 figures, 9 tables.

Lacelle, S.

1985-01-01

388

NMR approaches in structure-based lead discovery: Recent developments and new frontiers for targeting multi-protein complexes  

E-print Network

of the coin in water and NMR is water’s contribution to the decreasing of spectral crowding. Experiments are available which explore the concept that, for binding studies, solvent exposed residues are most influential. Being solvent accessible... : Experiences and lessons using NMR 3.1. Isotopic labelling strategies 3.2. Water(s) and NMR 3.3. Exploring multi-protein complexes and protein-protein interactions with NMR 3.4. Dynamics and NMR 4. Discussion and new frontiers...

Dias, David M.; Ciulli, Alessio

2014-08-28

389

Susceptibility-matched plugs for microcoil NMR probes  

PubMed Central

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 to 2 ?L) and larger volume (15 to 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 to 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

2010-01-01

390

Entanglement Control of Azobenzene by Photoisomerization in NMR Quantum Computer  

E-print Network

Entanglement control of qubits in a photoisomerizing molecule is studied in the context of an NMR quantum computer by taking azobenzene as an example. Azobenzene has two different isomers, {\\it{}trans}-azobenzene (TAB) and {\\it{}cis}-azobenzene (CAB), which can be interconverted by photoisomerization. Changing molecular structure leads to change in the spin-spin coupling constant, and hence leads to change in entangling operation time. We first obtain stable structures of TAB and CAB by {\\it ab initio} calculation. Then, we calculate the NMR spectra of these isomers and verify that they reproduce the chemical shift obtained experimentally with a good precision. Our result indicates that the coupling strength between a $^{15}$N and a $^{13}$C nuclei in the molecule changes by a large amount under photoisomerization.

Yasuda, Taiga; Nakahara, Mikio; Wakabayashi, Tomonari

2010-01-01

391

Sensitivity Quantification of Remote Detection NMR and MRI  

SciTech Connect

A sensitivity analysis of the remote detection NMR techniqueis presented. With remote detection, information about a sample isencoded onto a mobile sensor fluid, which facilitates a spatialseparation of encoding and detection of spin magnetization. This approachcan be interpreted as a two-dimensional NMR experiment, therefore thesame general formalism can be used for a sensitivity analysis. Eventhough remote detection is a point-by-point experiment, the sensitivitydoes not scale unfavorably with the number of detected points compared totransient detection. It is proportional to the relative sensitivitybetween the remote detector and the circuit that is used for encoding.The influence of the different signal decay times is analyzed, and thedistinction between spectroscopy and imaging experiments ismade.

Granwehr, Josef; Seeley, Juliette A.

2005-10-25

392

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

393

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

394

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

395

NMR study of mesomorphic solutions of cellulose derivatives  

SciTech Connect

Highly concentrated solutions of hydroxypropylcellulose and cellulose acetate give mesomorphic phases in a precise range of temperatures and concentrations. The existence of an orientational anisotropy in such solutions induces typical parameters of the high-resolution NMR spectra (chemical shift, splitting) that are similar to those of liquid crystal spectra. In the present work, the high-resolution NMR spectra of nuclei belonging to the solute molecules (D/sub 2/O and trifluoroacetic acid) were recorded as a function of various physical parameters such as temperature, concentration, and temporal change of the solutions. The specific variation of the orientational degree of order for each mesophase is described. In the case of the cellulose acetate/trifluoroacetic acid solution, an order parameter is calculated and a model for the orientational organization of the solution is described. 34 references, 10 figures, 1 table.

Dayan, S.; Fried, F.; Gilli, J.M.; Sixou, P.

1983-01-01

396

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

397

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

398

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

399

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

400

Bayesian Weighting of Statistical Potentials in NMR Structure Calculation  

PubMed Central

The use of statistical potentials in NMR structure calculation improves the accuracy of the final structure but also raises issues of double counting and possible bias. Because statistical potentials are averaged over a large set of structures, they may not reflect the preferences of a particular structure or data set. We propose a Bayesian method to incorporate a knowledge-based backbone dihedral angle potential into an NMR structure calculation. To avoid bias exerted through the backbone potential, we adjust its weight by inferring it from the experimental data. We demonstrate that an optimally weighted potential leads to an improvement in the accuracy and quality of the final structure, especially with sparse and noisy data. Our findings suggest that no universally optimal weight exists, and that the weight should be determined based on the experimental data. Other knowledge-based potentials can be incorporated using the same approach. PMID:24956116

Mechelke, Martin; Habeck, Michael

2014-01-01

401

In Vivo Multisite Oximetry using EPR-NMR Coimaging  

PubMed Central

Coimaging employing electron paramagnetic resonance (EPR) imaging and MRI is used for rapid in vivo oximetry conducted simultaneously across multiple organs of a mouse. A recently developed hybrid EPR-NMR coimaging instrument is used for both EPR and NMR measurements. Oxygen sensitive particulate EPR probe is implanted in small localized pockets, called sites, across multiple regions of a live mouse. Three dimensional MRI is used to generate anatomic visualization, providing precise locations of implant sites. The pO2 values, one for every site, are then estimated from EPR measurements. To account for radio frequency (RF) phase inhomogeneities inside a large resonator carrying a lossy sample, a generalization of an existing EPR data model is proposed. Utilization of known spectral lineshape, sparse distribution, and known site locations reduce the EPR data collection by more than an order of magnitude over a conventional spectral-spatial imaging, enhancing the feasibility of in vivo EPR oximetry for clinically relevant models. PMID:20850361

Ahmad, R.; Caia, G.; Potter, L.C.; Petryakov, S.; Kuppusamy, P.; Zweier, J.L.

2010-01-01

402

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

403

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

404

Membrane curvature modulation of protein activity determined by NMR.  

PubMed

In addition to specific intermolecular interactions, biological processes at membranes are also modulated by the physical properties of the membrane. One of these properties is membrane curvature. NMR methods are useful for studying how membrane curvature affects the binding and insertion of proteins into membranes as well as how proteins can affect membrane curvature properties. In many cases these interactions result in a marked change in protein activity. We have reviewed examples from a range of systems having varied mechanisms by which membrane curvature is linked to protein activity. Among the examples discussed are antimicrobial peptides, proteins affecting membrane fusion, rhodopsin, protein kinase C, phospholipase C-delta1, phosphatidylinositol-3 kinase-related kinases and tafazzin. This article is part of a Special Issue entitled: NMR Spectroscopy for Atomistic Views of Biomembranes and Cell Surfaces. Guest Editors: Lynette Cegelski and David P. Weliky. PMID:24835017

Epand, Richard M; D'Souza, Kenneth; Berno, Bob; Schlame, Michael

2015-01-01

405

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

406

Ferroelastic phase transition of bivo4 studied by v nmr  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) of V in the ferroelastic BiVO4 single crystals has been investigated at a fixed frequency of 6 MHz up to 533 K just above its Curie temperature, Tc = 528 K. The seven resonance lines of V(I = 7\\/2) due to the quadrupole interaction were measured in the three mutually perpendicular crystal planes. While the quadrupole

A. R. Lim; S. H. Choh; M. S. Jang

1989-01-01

407

NMR and Susceptibility Studies of MnSi above Tc  

Microsoft Academic Search

The itinerant helimagnet MnSi has been studied using NMR and susceptibility techniques above Tc. The magnitude and temperature dependence of the 55Mn Knight shift K, quadrupole coupling nuQ and the nuclear spin-lattice and spin-spin relaxation times T1 and T2 have been determined along with new high temperature measurements of the uniform susceptibility chi(0). Both K and nuQ are shown to

Hiroshi Yasuoka; V. Jaccarino; R. C. Sherwood; J. H. Wernick

1978-01-01

408

ADVANCED SOLIDS NMR STUDIES OF COAL STRUCTURE AND CHEMISTRY  

SciTech Connect

This report covers the progress made on the title project for the project period. The study of coal chemical structure is a vital component of research efforts to develop better chemical utilization of coals, and for furthering our basic understanding of coal geochemistry. In this grant we are addressing several structural questions pertaining to coals with advances in state of the art solids NMR methods. Our goals are twofold. First, we are interested in developing new methods that will enable us to measure important structural parameters in whole coals not directly accessible by other techniques. In parallel with these efforts we will apply these NMR methods in a study of the chemical differences between gas-sourcing and oil-sourcing coals. The NMR methods work will specifically focus on determination of the number and types of methylene groups, determination of the number and types of methane groups, identification of carbons adjacent to nitrogen and sites with exchangeable protons, and methods to more finely characterize the distribution of hydrogen in coals. The motivation for investigating these specific structural features of coals arises from their relevance to the chemical reactivity of coals, and their suitability for possible correlations with the oil sourcing potential of some types of coals. The coals to be studied and contrasted include oil-prone coals from Australia and Indonesia, those comprising the Argonne Premium Coal Sample bank, and other relevant samples. In this report period we have focused our work on 1 segment of the program. Our last report outlined progress in using our NMR editing methods with higher field operation where higher magic angle spinning rates are required. Significant difficulties were identified, and these have been the main subject of study during the most recent granting period.

NONE

1997-03-01

409

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

410

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.

411

Knowledge-based nonuniform sampling in multidimensional NMR  

Microsoft Academic Search

The full resolution afforded by high-field magnets is rarely realized in the indirect dimensions of multidimensional NMR experiments\\u000a because of the time cost of uniformly sampling to long evolution times. Emerging methods utilizing nonuniform sampling (NUS)\\u000a enable high resolution along indirect dimensions by sampling long evolution times without sampling at every multiple of the\\u000a Nyquist sampling interval. While the earliest

Adam D. Schuyler; Mark W. Maciejewski; Haribabu Arthanari; Jeffrey C. Hoch

412

NMR-based metabonomics: a useful platform of oncology research  

Microsoft Academic Search

Cancer threatens human health, thus research focusing on oncology has great significance. Metabonomics is the global quantitative\\u000a assessment of the dynamic metabolic response of a biological system to some exogenous or genetic pathophysiological perturbation.\\u000a The metabolites are detected in tissues or fluids by various analytical methods, such as nuclear magnetic resonance (NMR)\\u000a and mass spectroscopy. Metabonomics, as a tool, can

Qian Shang; Jun-Feng Xiang; Ya-Lin Tang

2010-01-01

413

High-resolution solid-state NMR of quadrupolar nuclei  

Microsoft Academic Search

Quadrupolar nuclei are the most abundant nuclear magnetic resonance (NMR)-receptive nuclei in the Earth's crust, and in many amorphous materials of technological interest (such as zeolite catalysts, ceramics and alloys), and have thus been intensively studied1-7. Of particular interest is the ability to resolve and quantitate the various types of sites present in a given material. Here we present a

Eric Oldfield; Hye Kyung C. Timken; Ben Montez; R. Ramachandran

1985-01-01

414

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

415

NMR Simulation of an Eight-State Quantum System  

E-print Network

The propagation of excitation along a one-dimensional chain of atoms is simulated by means of NMR. The physical system used as an analog quantum computer is a nucleus of 133-Cs (spin 7/2) in a liquid crystalline matrix. The Hamiltonian of migration is simulated by using a special 7-frequency pulse, and the dynamics is monitored by following the transfer of population from one of the 8 spin energy levels to the other.

A. K. Khitrin; B. M. Fung

2001-01-05

416

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

417

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

418

NMR imaging studies of asphaltene precipitation in asphalts  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) images were obtained on asphalts which were dissolved in toluene and titrated with iso-octane to the point of onset of flocculation. When iso-octane was added to the asphalt and the mixture stirred, asphaltene precipitation proceeded in a normal fashion. However, when the titrant was added slowly to minimize mixing at the iso-octane-asphalt-toluene interface, the images showed

Francis P. Miknis; Adam T. Pauli; Laurent C. Michon; Daniel A. Netzel

1998-01-01

419

A microfluidic high-resolution NMR flow probe.  

PubMed

A microfluidic high-resolution NMR flow probe based on a novel stripline detector chip is demonstrated. This tool is invaluable for the in situ monitoring of reactions performed in microreactors. As an example, the acetylation of benzyl alcohol with acetyl chloride was monitored. Because of the uncompromised (sub-Hz) resolution, this probe holds great promise for metabolomics studies, as shown by an analysis of 600 nL of human cerebrospinal fluid. PMID:19320484

Bart, Jacob; Kolkman, Ard J; Oosthoek-de Vries, Anna Jo; Koch, Kaspar; Nieuwland, Pieter J; Janssen, Hans J W G; van Bentum, Jan P J M; Ampt, Kirsten A M; Rutjes, Floris P J T; Wijmenga, Sybren S; Gardeniers, Han J G E; Kentgens, Arno P M

2009-04-15

420

NMR characterization of synthetic and modified aluminum orthophosphates  

Microsoft Academic Search

³¹P, ²⁷Al, and ¹H MAS-NMR spectra of aluminum phosphates (Al\\/P = 1), obtained from different salts (nitrate, chloride, and sulfate) have been analyzed. Thermal treatment of samples results in the transformation of amorphous into crystalline AlPOâ samples (tridymite or α-cristobalite polymorphs). Structural changes induced by thermal treatments or incorporation of foreign ions (Li{sup +}, F⁻, or SOâ²⁻) are also analyzed

J. Sanz; J. M. Campelo; J. M. Marinas

1991-01-01

421

Integrated standardization concept for Angelica botanicals using quantitative NMR  

PubMed Central

Despite numerous in vitro/vivo and phytochemical studies, the active constituents of Angelica sinensis (AS) have not been conclusively identified for the standardization to bioactive markers. Phytochemical analyses of AS extracts and fractions that demonstrate activity in a panel of in vitro bioassays, have repeatedly pointed to ligustilide as being (associated with) the active principle(s). Due to the chemical instability of ligustilide and related issues in GC/LC analyses, new methods capable of quantifying ligustilide in mixtures that do not rely on an identical reference standard are in high demand. This study demonstrates how NMR can satisfy the requirement for simultaneous, multi-target quantification and qualitative identification. First, the AS activity was concentrated into a single fraction by RP-solid-phase extraction, as confirmed by an (anti-)estrogenicity and cytotoxicity assay. Next, a quantitative 1H NMR (qHNMR) method was established and validated using standard compounds and comparing processing methods. Subsequent 1D/2D NMR and qHNMR analysis led to the identification and quantification of ligustilide and other minor components in the active fraction, and to the development of quality criteria for authentic AS preparations. The absolute and relative quantities of ligustilide, six minor alkyl phthalides, and groups of phenylpropanoids, polyynes, and poly-unsaturated fatty acids were measured by a combination of qHNMR and 2D COSY. The qNMR approach enables multi-target quality control of the bioactive fraction, and enables the integrated biological and chemical standardization of AS botanicals. This methodology can potentially be transferred to other botanicals with active principles that act synergistically, or that contain closely related and/or constituents, which have not been conclusively identified as the active principles. PMID:21907766

Gödecke, Tanja; Yao, Ping; Napolitano, José G.; Nikoli?, Dejan; Dietz, Birgit M.; Bolton, Judy L.; van Breemen, Richard B.; Farnsworth, Norman R.; Chen, Shao-Nong; Lankin, David C.; Pauli, Guido F.

2011-01-01

422

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

423

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

ERIC Educational Resources Information Center

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

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

2012-01-01

424

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

425

Solid State NMR Studies of the Aluminum Hydride Phases  

NASA Technical Reports Server (NTRS)

Several solid state NMR techniques including magic-angle-spinning (MAS) and multiple-quantum (MQ) MAS experiments have been used to characterize various AlH3 samples. MAS-NMR spectra for the 1H and 27Al nuclei have been obtained on a variety of AlH3 samples that include the (beta)- and (gamma)- phases as well as the most stable (alpha)-phase. While the dominant components in these NMR spectra correspond to the aluminum hydride phases, other species were found that include Al metal, molecular hydrogen (H2), as well as peaks that can be assigned to Al-O species in different configurations. The occurrence and concentration of these extraneous components are dependent upon the initial AlH3 phase composition and preparation procedures. Both the (beta)-AlH3 and (gamma)-AlH3 phases were found to generate substantial amounts of Al metal when the materials were stored at room temperature while the (alpha)-phase materials do not exhibit these changes.

Hwang, Son-Jong; Bowman, R. C., Jr.; Graetz, Jason; Reilly, J. J.

2006-01-01

426

NMR studies of molecules in liquid crystals and graphite  

SciTech Connect

NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.

Rosen, M.E.

1992-06-01

427

NMR Quantum Information Processing with Para-Hydrogen  

E-print Network

This thesis addresses the problems of initialization and separability in liquid state NMR based quantum information processors. We prepare pure quantum states lying above the entanglement threshold. Our pure state quantum computer derives its purity from the highly polarized nuclear spin states in the para-hydrogen molecule. The thesis begins with a critique of conventional NMR based quantum information processing outlining the major strengths and weaknesses of the technology. We describe the enhanced magnetic ordering of the nuclear spin states in para-hydrogen and an initialization experiment exploiting this effect to achieve pure, entangled states. These states can indeed be used as initial states in implementing quantum algorithms: we describe mplementations of the Deutsch and the Grover quantum algorithms. The "twirl" operation converts a completely arbitrary input state to a Werner singlet. The NMR implementation of this operation is taken up. We also analyze the possibility of sharing the purity of some highly polarized qubits in a quantum computer onto quantum subspaces of arbitrary dimensions, and whether these sharing operations increase or decrease the likelihood of entanglement.

M. S. Anwar

2005-09-07

428

Chirped CPMG for well-logging NMR applications  

NASA Astrophysics Data System (ADS)

In NMR well-logging, the measurement apparatus typically consists of a permanent magnet which is inserted into a bore, and the sample is the rock surrounding the borehole. When compared to the conditions of standard NMR experiments, this application is thus challenged by relatively weak and invariably inhomogeneous B0 and B1 fields. Chemical shift information is not generally obtained in these measurements. Instead, diffusivity, porosity and permeability information is collected from multi-echo decay measurements - most often using a Carr-Purcell Meiboom-Gill (CPMG) pulse sequence to enhance the experiment’s limited sensitivity. In this work, we explore the consequences of replacing the hard square pulses used in a typical CPMG sequence with chirped pulses sweeping a range of frequencies. The greater bandwidths that for a maximum B1 level can be excited by chirped pulses translates into marked expansion of the detection volume, and thus significant signal-to-noise improvements when compared to standard CPMG acquisitions using hard pulses. This improvement, usually amounting to signal enhancements ?3, can be used to reduce the experimental time of NMR well-logging measurements, for measuring T2 even when B0 and B1 inhomogenieties complicate the measurements, and opening new opportunities in the determination of diffusional properties.

Casabianca, Leah B.; Mohr, Daniel; Mandal, Soumyajit; Song, Yi-Qiao; Frydman, Lucio

2014-05-01

429

NMR of laser-polarized xenon in human?blood  

PubMed Central

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude. The enhanced polarization has allowed advances in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), including polarization transfer to molecules and imaging of lungs and other void spaces. A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization. Described herein is an efficient method for the introduction of laser-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR/MRI signals. Using this method, we have made the first observation of the time-resolved process of xenon penetrating the red blood cells in fresh human blood—the xenon residence time constant in the red blood cells was measured to be 20.4 ± 2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR/MRI is discussed in light of their respective relaxation and partitioning properties. PMID:8917521

Bifone, A.; Song, Y.-Q.; Seydoux, R.; Taylor, R.?E.; Goodson, B.?M.; Pietrass, T.; Budinger, T.?F.; Navon, G.; Pines, A.

1996-01-01

430

NMR Studies of f-Electron Magnetism in Actinide Compounds  

NASA Astrophysics Data System (ADS)

Many interesting and important 5f electron-related phenomena remain to be understood in actinide metals and intermetallic compounds. In this talk I will highlight recent results from our Uranium NMR Group in Tokai. As a highly sensitive, microscopic probe of magnetic effects, ligand NMR has been used to characterize 5f-electron behavior in the metallic antiferromagnets UPtGa_5, UNiGa_5, and UGa_3. In the first two cases, we find the interesting phenomenon of a transferred Van Vleck shift^1, and for the UGa3 we have reported a fascinating ``double" phase transition to antiferromagnetic order starting at TN = 67 K.^2 Our program also includes direct and indirect studies of ^235U NMR in uranium compounds. We have recently performed an indirect measurement of ^235U spin-lattice relaxation in URh3 for 100K < T < 250K, the first such measurement, which will also be discussed. 1. N.J. Curro, et al., Phys. Rev. B64 180514-1 (2001). 2. S. Kambe, et al., Phys. Rev. B, Rapid Communications, to be published.

Walstedt, R. E.

2003-03-01

431

Sensitivity enhancement of double quantum NMR spectroscopy by modified CPMG  

NASA Astrophysics Data System (ADS)

A modified Carr-Purcell-Meiboom-Gill (CPMG) sequence for sensitivity enhancement of dipolar coupled homonuclear spin pairs in static solid-state NMR is presented. The modified CPMG block uses the Hahn-solid-Hahn echo as basic element of the CPMG echo train to refocus the homonuclear dipolar coupling and chemical shift anisotropy. The new CPMG sequence is dubbed as Hahn-solid-Hahn Carr-Purcell-Meiboom-Gill (HSHCPMG). We demonstrate a gain in signal to noise ratio of approximately 4.2 using HSHCPMG sequence in double quantum filtered CP experiment for 5%-13C2-15N-glycine. The resulting gain in sensitivity in the spikelet spectrum does not compromise the anisotropic information that is available from static NMR lineshapes. As an example, relative orientation angles of chemical shift anisotropy tensors for the alpha and carbonyl carbons in glycine are determined from the 2D DOQSY experiment recorded with the HSHCPMG block in the acquisition dimension. The resultant relative orientation angles of the two CSA tensors are compared to those obtained from 2D DOQSY experiment acquired without sensitivity enhancement as well as to the data as available from single crystal NMR experiments.

Gowda, Chandrakala M.; Agarwal, Vipin; Kentgens, Arno P. M.

2012-10-01

432

2D NMR-spectroscopic screening reveals polyketides in ladybugs.  

PubMed

Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature's cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature's structure space and suggests that insect metabolomes remain vastly underexplored. PMID:21646540

Deyrup, Stephen T; Eckman, Laura E; McCarthy, Patrick H; Smedley, Scott R; Meinwald, Jerrold; Schroeder, Frank C

2011-06-14

433

Error tolerant NMR backbone resonance assignment and automated structure generation.  

PubMed

Error tolerant backbone resonance assignment is the cornerstone of the NMR structure determination process. Although a variety of assignment approaches have been developed, none works sufficiently well on noisy fully automatically picked peaks to enable the subsequent automatic structure determination steps. We have designed an integer linear programming (ILP) based assignment system (IPASS) that has enabled fully automatic protein structure determination for four test proteins. IPASS employs probabilistic spin system typing based on chemical shifts and secondary structure predictions. Furthermore, IPASS extracts connectivity information from the inter-residue information and the (automatically picked) (15)N-edited NOESY peaks which are then used to fix reliable fragments. When applied to automatically picked peaks for real proteins, IPASS achieves an average precision and recall of 82% and 63%, respectively. In contrast, the next best method, MARS, achieves an average precision and recall of 77% and 36%, respectively. The assignments generated by IPASS are then fed into our protein structure calculation system, FALCON-NMR, to determine the 3D structures without human intervention. The final models have backbone RMSDs of 1.25Å, 0.88Å, 1.49Å, and 0.67Å to the reference native structures for proteins TM1112, CASKIN, VRAR, and HACS1, respectively. The web server is publicly available at http://monod.uwaterloo.ca/nmr/ipass. PMID:21328705

Alipanahi, Babak; Gao, Xin; Karakoc, Emre; Li, Shuai Cheng; Balbach, Frank; Feng, Guangyu; Donaldson, Logan; Li, Ming

2011-02-01

434

A small-diameter NMR logging tool for groundwater investigations.  

PubMed

A small-diameter nuclear magnetic resonance (NMR) logging tool has been developed and field tested at various sites in the United States and Australia. A novel design approach has produced relatively inexpensive, small-diameter probes that can be run in open or PVC-cased boreholes as small as 2 inches in diameter. The complete system, including surface electronics and various downhole probes, has been successfully tested in small-diameter monitoring wells in a range of hydrogeological settings. A variant of the probe that can be deployed by a direct-push machine has also been developed and tested in the field. The new NMR logging tool provides reliable, direct, and high-resolution information that is of importance for groundwater studies. Specifically, the technology provides direct measurement of total water content (total porosity in the saturated zone or moisture content in the unsaturated zone), and estimates of relative pore-size distribution (bound vs. mobile water content) and hydraulic conductivity. The NMR measurements show good agreement with ancillary data from lithologic logs, geophysical logs, and hydrogeologic measurements, and provide valuable information for groundwater investigations. PMID:23425428

Walsh, David; Turner, Peter; Grunewald, Elliot; Zhang, Hong; Butler, James J; Reboulet, Ed; Knobbe, Steve; Christy, Tom; Lane, John W; Johnson, Carole D; Munday, Tim; Fitzpatrick, Andrew

2013-01-01

435

DNA Nanotubes for NMR Structure Determination of Membrane Proteins  

PubMed Central

Structure determination of integral membrane proteins by solution NMR represents one of the most important challenges of structural biology. A Residual-Dipolar-Coupling-based refinement approach can be used to solve the structure of membrane proteins up to 40 kDa in size, however, a weak-alignment medium that is detergent-resistant is required. Previously, availability of media suitable for weak alignment of membrane proteins was severely limited. We describe here a protocol for robust, large-scale synthesis of detergent-resistant DNA nanotubes that can be assembled into dilute liquid crystals for application as weak-alignment media in solution NMR structure determination of membrane proteins in detergent micelles. The DNA nanotubes are heterodimers of 400nm-long six-helix bundles each self-assembled from a M13-based p7308 scaffold strand and >170 short oligonucleotide staple strands. Compatibility with proteins bearing considerable positive charge as well as modulation of molecular alignment, towards collection of linearly independent restraints, can be introduced by reducing the negative charge of DNA nanotubes via counter ions and small DNA binding molecules. This detergent-resistant liquid-crystal media offers a number of properties conducive for membrane protein alignment, including high-yield production, thermal stability, buffer compatibility, and structural programmability. Production of sufficient nanotubes for 4–5 NMR experiments can be completed in one week by a single individual. PMID:23518667

Bellot, Gaëtan; McClintock, Mark A.; Chou, James J; Shih, William M.

2013-01-01

436

Development of a Hybrid EPR/NMR Coimaging System  

PubMed Central

Electron paramagnetic resonance imaging (EPRI) is a powerful technique that enables spatial mapping of free radicals or other paramagnetic compounds; however, it does not in itself provide anatomic visualization of the body. Proton magnetic resonance imaging (MRI) is well suited to provide anatomical visualization. A hybrid EPR/NMR coimaging instrument was constructed that utilizes the complementary capabilities of both techniques, superimposing EPR and proton-MR images to provide the distribution of paramagnetic species in the body. A common magnet and field gradient system is utilized along with a dual EPR and proton-NMR resonator assembly, enabling coimaging without the need to move the sample. EPRI is performed at ~1.2 GHz/~40 mT and proton MRI is performed at 16.18 MHz/~380 mT; hence the method is suitable for whole-body coimaging of living mice. The gradient system used is calibrated and controlled in such a manner that the spatial geometry of the two acquired images is matched, enabling their superposition without additional postprocessing or marker registration. The performance of the system was tested in a series of phantoms and in vivo applications by mapping the location of a paramagnetic probe in the gastrointestinal (GI) tract of mice. This hybrid EPR/NMR coimaging instrument enables imaging of paramagnetic molecules along with their anatomic localization in the body. PMID:17659621

Samouilov, Alexandre; Caia, George L.; Kesselring, Eric; Petryakov, Sergey; Wasowicz, Tomasz; Zweier, Jay L.

2010-01-01

437

23Na and 1H NMR Microimaging of Intact Plants  

NASA Astrophysics Data System (ADS)

23Na NMR microimaging is described to map, for the first time, the sodium distribution in living plants. As an example, the response of 6-day-old seedlings of Ricinus communis to exposure to sodium chloride concentrations from 5 to 300 mM was observed in vivo using 23Na as well as 1H NMR microimaging. Experiments were performed at 11.75 T with a double resonant 23Na- 1H probehead. The probehead was homebuilt and equipped with a climate chamber. T1 and T2 of 23Na were measured in the cross section of the hypocotyl. Within 85 min 23Na images with an in-plane resolution of 156 × 156 ?m were acquired. With this spatial information, the different types of tissue in the hypocotyl can be discerned. The measurement time appears to be short compared to the time scale of sodium uptake and accumulation in the plant so that the kinetics of salt stress can be followed. In conclusion, 23Na NMR microimaging promises great potential for physiological studies of the consequences of salt stress on the macroscopic level and thus may become a unique tool for characterizing plants with respect to salt tolerance and salt sensitivity.

Olt, Silvia; Krötz, Eva; Komor, Ewald; Rokitta, Markus; Haase, Axel

2000-06-01

438

Multinuclear NMR approach to coal fly ash characterization  

SciTech Connect

This report describes the application of various nuclear magnetic resonance (NMR) techniques to study the hydration kinetics and mechanisms, the structural properties, and the adsorption characteristics of coal fly ash. Coal fly ash samples were obtained from the Dave Johnston and Laramie River electric power generating plants in Wyoming. Hydrogen NMR relaxation times were measured as a function of time to observe the kinetics of hydration for the two coal fly ashes at different temperatures and water-to-cement ration. The kinetic data for the hydrated coal fly ashes were compared to the hydration of portland cement. The mechanism used to describe the kinetic data for the hydration of portland cement was applied, with reservation, to describe the hydration of the coal fly ashes. The results showed that the coal fly ashes differ kinetically from that of portland cement and from each other. Consequently, both coal fly ashes were judged to be poorer cementitious materials than portland cement. Carbon-13 NMR CP/MAS spectra were obtained for the anhydrous coal fly ashes in an effort to determine the type of organic species that may be present, either adsorbed on the surface or entrained.

Netzel, D.A.

1991-09-01

439

NMR Studies of Molecular Orientation and Dynamics in Spider silk  

NASA Astrophysics Data System (ADS)

Spider dragline silk has a unique combination of strength and extensibility that has been difficult to achieve in synthetic polymer fibres and has inspired industrial efforts to produce genetically engineered analogues. In light of these efforts elsewhere, we describe solid-state NMR experiments that elucidate the molecular structure and dynamics of this remarkable material. These experiments include the use of a 2-D exchange NMR experiment known as DECODER in which the sample is reoriented through a discrete angle during the mixing time. This experiment allows a reconstruction of the orientation distribution of the protein backbone. Our data is well described by a two-component distribution where the protein backbones of both components are preferentially aligned along the silk fibre. This experiment is also sensitive to molecular motion on a wide range of time-scales, and is employed to study changes in the silk as a function of fibre extension and hydration. Hydrated silk undergoes a remarkable phenomena known as supercontraction where fibres shrink by up to 50% in length while swelling in diameter. DECODER NMR of fully and partially supercontracted silk reveals that supercontraction occurs through a process of local phase transitions where water disrupts inter- and intra-chain hydrogen bonds.

Michal, Carl; Eles, Philip

2004-05-01

440

Amino acid analysis of spider dragline silk using ¹H NMR.  

PubMed

The amino acid composition of Nephila clavipes dragline silk fiber was determined by conducting ¹H nuclear magnetic resonance (NMR) spectroscopy experiments on acid-hydrolyzed material. N. clavipes dragline silk was found to consist of 43.0±0.6% Gly, 29.3±0.2% Ala, 9.1±0.1% Glx, 4.0±0.1% Leu, 3.3±0.1% Tyr, 3.4±0.2% Ser, 2.7±0.1% Pro, 2.1±0.1% Arg, 1.07±0.05% Asx, 0.96±0.05% Val, 0.48±0.03% Thr, 0.35±0.03% Phe, and 0.28±0.03% Ile. Compared with standard chromatography-based amino acid analysis (AAA), the chemical resolution of NMR allows for an amino acid solution to be characterized without separation and is shown to provide considerably higher precision. This allows for more accurate statistics on the variability of amino acids in spider dragline silk. In general, this ¹H NMR AAA technique is applicable to a large range of proteins and peptides for precise composition characterization, especially when the precise content of a minor component is critical and relatively large amounts of sample are available (microgram to milligram quantities). PMID:23727559

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

2013-09-15

441

13C NMR spectroscopy applications to brain energy metabolism  

PubMed Central

13C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of 13C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the 13C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of 13C NMR data. Finally, new perspectives and applications offered by 13C hyperpolarization are described. PMID:24367329

Rodrigues, Tiago B.; Valette, Julien; Bouzier-Sore, Anne-Karine

2013-01-01

442

2D NMR-spectroscopic screening reveals polyketides in ladybugs  

PubMed Central

Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature’s cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature’s structure space and suggests that insect metabolomes remain vastly underexplored. PMID:21646540

Deyrup, Stephen T.; Eckman, Laura E.; McCarthy, Patrick H.; Smedley, Scott R.; Meinwald, Jerrold; Schroeder, Frank C.

2011-01-01

443

Probing coiled-coil assembly by paramagnetic NMR spectroscopy.  

PubMed

Here a new method to determine the oligomeric state and orientation of coiled-coil peptide motifs is described. Peptides K and E, which are designed to form a parallel heterodimeric complex in aqueous solution, were labeled with the aromatic amino acids tryptophan and tyrosine on the C-terminus respectively as 'fingerprint' residues. One of the peptides was also labeled with the paramagnetic probe MTSL. One dimensional proton NMR spectroscopy was used to study the peptide quaternary structure by monitoring the signal suppression of the aromatic labels due to proximity of the nitroxyl radical. 1D-NMR confirmed that the peptides K and E form a heterodimeric coiled coil with a parallel orientation. In addition, fluorescence emission quenching of the aromatic labels due to electron exchange with a nitroxyl radical confirmed the parallel coiled coil orientation. Thus, paramagnetic nitroxide and aromatic fluorophore labeling of peptides yields valuable information regarding the quaternary structure from 1D-NMR and steady-state fluorescence measurements. This convenient method is useful not only to investigate coiled coil assembly, but can also be applied to any defined supramolecular assembly. PMID:25428174

Zheng, TingTing; Boyle, Aimee; Robson Marsden, Hana; Valdink, Dayenne; Martelli, Giuliana; Raap, Jan; Kros, Alexander

2015-01-28

444

MOTOR: model assisted software for NMR structure determination.  

PubMed

Eukaryotic proteins with important biological function can be partially unstructured, conformational flexible, or heterogenic. Crystallization trials often fail for such proteins. In NMR spectroscopy, parts of the polypeptide chain undergoing dynamics in unfavorable time regimes cannot be observed. De novo NMR structure determination is seriously hampered when missing signals lead to an incomplete chemical shift assignment resulting in an information content of the NOE data insufficient to determine the structure ab initio. We developed a new protein structure determination strategy for such cases based on a novel NOE assignment strategy utilizing a number of model structures but no explicit reference structure as it is used for bootstrapping like algorithms. The software distinguishes in detail between consistent and mutually exclusive pairs of possible NOE assignments on the basis of different precision levels of measured chemical shifts searching for a set of maximum number of consistent NOE assignments in agreement with 3D space. Validation of the method using the structure of the low molecular-weight-protein tyrosine phosphatase A (MptpA) showed robust results utilizing protein structures with 30-45% sequence identity and 70% of the chemical shift assignments. About 60% of the resonance assignments are sufficient to identify those structural models with highest conformational similarity to the real structure. The software was benchmarked by de novo solution structures of fibroblast growth factor 21 (FGF21) and the extracellular fibroblast growth factor receptor domain FGFR4 D2, which both failed in crystallization trials and in classical NMR structure determination. PMID:23852655

Schieborr, Ulrich; Sreeramulu, Sridhar; Elshorst, Bettina; Maurer, Marcus; Saxena, Krishna; Stehle, Tanja; Kudlinzki, Denis; Gande, Santosh Lakshmi; Schwalbe, Harald

2013-11-01

445

Rheo-NMR Measurements of Cocoa Butter Crystallized Under  

SciTech Connect

Modifications of a benchtop NMR instrument were made to apply temperature control to a shearing NMR cell. This has enabled the determination in situ of the solid fat content (SFC) of cocoa butter under shearing conditions. The cocoa butter was cooled at 3 C/min to three final temperatures of 17.5, 20.0, and 22.5 C with applied shear rates between 45 and 720 s-1. Polymorphic transitions of the cocoa butter were determined using synchrotron X-ray diffraction with an identical shearing system constructed of Lexan. Sheared samples were shown to have accelerated phase transitions compared to static experiments. In experiments where form V was confirmed to be the dominant polymorph, the final SFC averaged around 50%. However, when other polymorphic forms were formed, a lower SFC was measured because the final temperature was within the melting range of that polymorph and only partial crystallization happened. A shear rate of 720 s-1 delayed phase transitions, likely due to viscous heating of the sample. Pulsed NMR is an invaluable tool for determining the crystalline fraction in hydrogen containing materials, yet its use for fundamental and industrial research on fat or alkanes crystallization under shear has only recently been developed.

Mudge, E.; Mazzanti, G

2009-01-01

446

Automated NMR relaxation dispersion data analysis using NESSY  

PubMed Central

Background Proteins are dynamic molecules with motions ranging from picoseconds to longer than seconds. Many protein functions, however, appear to occur on the micro to millisecond timescale and therefore there has been intense research of the importance of these motions in catalysis and molecular interactions. Nuclear Magnetic Resonance (NMR) relaxation dispersion experiments are used to measure motion of discrete nuclei within the micro to millisecond timescale. Information about conformational/chemical exchange, populations of exchanging states and chemical shift differences are extracted from these experiments. To ensure these parameters are correctly extracted, accurate and careful analysis of these experiments is necessary. Results The software introduced in this article is designed for the automatic analysis of relaxation dispersion data and the extraction of the parameters mentioned above. It is written in Python for multi platform use and highest performance. Experimental data can be fitted to different models using the Levenberg-Marquardt minimization algorithm and different statistical tests can be used to select the best model. To demonstrate the functionality of this program, synthetic data as well as NMR data were analyzed. Analysis of these data including the generation of plots and color coded structures can be performed with minimal user intervention and using standard procedures that are included in the program. Conclusions NESSY is easy to use open source software to analyze NMR relaxation data. The robustness and standard procedures are demonstrated in this article. PMID:22032230

2011-01-01

447

Study by (23)Na-NMR, (1)H-NMR, and ultraviolet spectroscopy of the thermal stability of an 11-basepair oligonucleotide.  

PubMed Central

23Na-NMR, (1)H-NMR, and ultraviolet (UV) spectroscopy have been used to study the thermal stability of the double helix structure of an 11-basepair oligonucleotide. The denaturation curves obtained by (23)Na-NMR and UV are analyzed using a two-state model. The melting temperature and DeltaH(0) obtained are identical within experimental error, suggesting that modifications in the ionic atmosphere, probed by (23)Na-NMR, and the modifications in the basepair stacking, probed by UV, occur at the same temperature. Additional dynamical information on the denaturation process has been obtained by (1)H-NMR: slow exchange is observed between the thymine methyl resonances, and the disappearance of imino protons shows that a single basepair opening does not contribute significantly to proton exchange. PMID:10653819

Cahen, P; Luhmer, M; Fontaine, C; Morat, C; Reisse, J; Bartik, K

2000-01-01

448

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, January 1, 1992--March 31, 1992  

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 at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

Zilm, K.W.

1992-07-01

449

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, September 13, 1991--December 31, 1991  

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

450

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, January 1, 1993--March 31, 1993  

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 at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

Zilm, K.W.

1993-07-01

451

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, April 1, 1992--June 30, 1992  

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 at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

Zilm, K.W.

1992-09-01

452

NMR local range investigations in amorphous starchy substrates I. Structural heterogeneity probed by 13C CP–MAS NMR  

Microsoft Academic Search

The 13C CP–MAS (Cross Polarization and Magic Angle Spinning) NMR signatures of a series of amorphous and semi-crystalline samples prepared from various starchy substrates (native potato starch, amylopectin, amylose) following different techniques of preparation (casting, freeze drying, solvent exchange) are compared. Decompositions of the C1 resonance spectra reveal the existence of four or five main types of ?(1–4) linkages, which

H Bizot; J Emery; J. Y Buzaré; A Buléon

2001-01-01

453

A new laboratory approach to shale analysis using NMR relaxometry  

USGS Publications Warehouse

Low-field nuclear magnetic resonance (LF-NMR) relaxometry is a non-invasive technique commonly used to assess hydrogen-bearing fluids in petroleum reservoir rocks. Measurements made using LF-NMR provide information on rock porosity, pore-size distributions, and in some cases, fluid types and saturations (Timur, 1967; Kenyon et al., 1986; Straley et al., 1994; Brown, 2001; Jackson, 2001; Kleinberg, 2001; Hurlimann et al., 2002). Recent improvements in LF-NMR instrument electronics have made it possible to apply methods used to measure pore fluids to assess highly viscous and even solid organic phases within reservoir rocks. T1 and T2 relaxation responses behave very differently in solids and liquids; therefore the relationship between these two modes of relaxation can be used to differentiate organic phases in rock samples or to characterize extracted organic materials. Using T1-T2 correlation data, organic components present in shales, such as kerogen and bitumen, can be examined in laboratory relaxometry measurements. In addition, implementation of a solid-echo pulse sequence to refocus T2 relaxation caused by homonuclear dipolar coupling during correlation measurements allows for improved resolution of solid-phase protons. LF-NMR measurements of T1 and T2 relaxation time distributions were carried out on raw oil shale samples from the Eocene Green River Formation and pyrolyzed samples of these shales processed by hydrous pyrolysis and techniques meant to mimic surface and in-situ retorting. Samples processed using the In Situ Simulator approach ranged from bitumen and early oil generation through to depletion of petroleum generating potential. The standard T1-T2 correlation plots revealed distinct peaks representative of solid- and liquid-like organic phases; results on the pyrolyzed shales reflect changes that occurred during thermal processing. The solid-echo T1 and T2 measurements were used to improve assessment of the solid organic phases, specifically kerogen, thermally degraded kerogen, and char. Integrated peak areas from the LF-NMR results representative of kerogen and bitumen were found to be well correlated with S1 and S2 parameters from Rock-Eval programmed pyrolysis. This study demonstrates that LFNMR relaxometry can provide a wide range of information on shales and other reservoir rocks that goes well beyond porosity and pore-fluid analysis.

Washburn, Kathryn E.; Birdwell, Justin E.

2013-01-01

454

Broadband solid-state MAS NMR of paramagnetic systems.  

PubMed

The combination of new magnet and probe technology with increasingly sophisticated pulse sequences has resulted in an increase in the number of applications of solid-state nuclear magnetic resonance (NMR) spectroscopy to paramagnetic materials and biomolecules. The interaction between the paramagnetic metal ions and the NMR-active nuclei often yields crucial structural or electronic information about the system. In particular the application of magic-angle spinning (MAS) has been shown to be crucial to obtaining resolution that is sufficiently high for studying complex systems. However such systems are generally extremely difficult to study as the shifts and shift anisotropies resulting from the same paramagnetic interaction broaden the spectrum beyond excitation and detection, and the paramagnetic relaxation enhancement (PRE) shortens the lifetimes of the excited signals considerably. One specific area that has therefore been receiving significant attention in recent years, and for which great improvements have been seen, is the development of broadband NMR sequences. The development of new excitation and inversion sequences for paramagnetic systems under MAS has often made the difference between the spectrum being unobtainable, and a complete NMR study being possible. However the development of the new sequences must explicitly take account of the modulation of the anisotropic shift interactions due to the sample rotation, with the resulting spin dynamics often being complicated considerably. The NMR sequences can either be helped or hindered by MAS, with the efficiency of some pulse schemes being destroyed, and others being greatly enhanced. This review describes the pulse sequences that have recently been proposed for broadband excitation, inversion, and refocussing of the signal components of paramagnetic systems. In doing so we define exactly what is meant by "broadband" under spinning conditions, and what the perfect pulse scheme should deliver. We also give a unified description of the spin dynamics under MAS which highlights the strengths and weaknesses of the various schemes, and which can be used as guidance for future research in this area. All the reviewed pulse schemes are evaluated both with simulations and experimental data obtained on the battery material LiFe0.5Mn0.5PO4 which is typical of the complexity of the paramagnetic systems that are currently under study. PMID:25669740

Pell, Andrew J; Pintacuda, Guido

2015-02-01

455

'Shim pulses' for NMR spectroscopy in inhomogeneous magneticfields  

SciTech Connect

NMR spectroscopy conveys information about chemical structure through ppm-scale shifts of the resonance frequency depending on the chemical environment. In order to observe these small shifts, magnets with highly homogeneous magnetic field B{sub 0} are used. The high cost and large size of these magnets are a consequence of the requirement for high homogeneity. In this contribution we introduce a new method for recording high-resolution NMR spectra from samples in inhomogeneous B{sub 0}, opening up the possibility of exploiting magnets of lower homogeneity and cost. Instead of using the traditional B{sub 0} ''shim coils'', adiabatic radiofrequency (RF) pulse sequences and modulated B{sub 0} gradients generated by coils in the probe are used to produce ''shim pulses''. A great deal of work has been devoted to finding methods for retrieving chemical shift information even when B{sub 0} is inhomogeneous. One class of methods relies on zero- or multiple quantum coherences which evolve independently of B{sub 0}. These methods are inherently two-dimensional and the high-resolution information is obtained indirectly. In order to minimize experimental time it is desirable to acquire a high-resolution spectrum directly just as for traditional NMR in homogeneous fields. A further advantage with direct acquisition is that modification of already existing multidimensional NMR techniques is facilitated. A fundamentally different approach utilizes inhomogeneity of the RF magnetic field to periodically refocus the phase dispersion from the inhomogeneous B{sub 0}. With this technique a high-resolution spectrum can indeed be acquired in a single shot. The main drawback is the requirement for spatial matching between the RF and B{sub 0} inhomogeneities. Based on this latter technique we propose the use of ''shim pulses'', i.e. modulated, spatially constant, B{sub 0} gradient pulses together with spatially homogeneous adiabatic frequency sweeps to induce non-linear phase shifts in three dimensions. An intuitive understanding of the approach can be obtained from the following: An adiabatic full passage applied to transverse magnetization effectively rotates the magnetization in the transverse plane with an amount that depends on the frequency offset. In homogeneous B{sub 0} this gives rise to a ''phase roll'' across the NMR spectrum. If the adiabatic full passage is applied in the presence of a constant B{sub 0} gradient, a phase shift approximately linear in space will be the result. A second adiabatic passage reverses this phase shift and the adiabatic double passage constitutes effectively a 360{sup o} pulse. However, if the amplitude of the B{sub 0} gradient is changing during the adiabatic passages, phase shifts, which are non-linear in space, can be achieved. With a proper choice of the RF and gradient modulation functions, the phase dispersion from the inhomogeneous B{sub 0} can be canceled. Application of a shim pulse between each detected point in the time-domain NMR signal yields an NMR spectrum free from the broadening caused by the B{sub 0} inhomogeneity.

Topgaard, Daniel; Martin, Rachel W.; Sakellariou, Dimitris; Meriles, Carlos; Pines, Alexander

2004-05-19

456

Isotope Labeling for Solution and Solid-State NMR Spectroscopy of Membrane Proteins  

PubMed Central

In this chapter, we summarize the isotopic labeling strategies used to obtain high-quality solution and solid-state NMR spectra of biological samples, with emphasis on integral membrane proteins (IMPs). While solution NMR is used to study IMPs under fast tumbling conditions, such as in the presence of detergent micelles or isotropic bicelles, solid-state NMR is used to study the structure and orientation of IMPs in lipid vesicles and bilayers. In spite of the tremendous progress in biomolecular NMR spectroscopy, the homogeneity and overall quality of the sample is still a substantial obstacle to overcome. Isotopic labeling is a major avenue to simplify overlapped spectra by either diluting the NMR active nuclei or allowing the resonances to be separated in multiple dimensions. In the following we will discuss isotopic labeling approaches that have been successfully used in the study of IMPs by solution and solid-state NMR spectroscopy. PMID:23076578

Verardi, Raffaello; Traaseth, Nathaniel J.; Masterson, Larry R.; Vostrikov, Vitaly V.; Veglia, Gianluigi

2013-01-01

457

Crystallography & NMR System: A New Software Suite for Macromolecular Structure Determination  

Microsoft Academic Search

A new software suite, called Crystallography & NMR System (CNS), has been developed for macromolecular structure determination by X-ray crystallography or solution nuclear magnetic resonance (NMR) spectro- scopy. In contrast to existing structure-determination programs the architecture of CNS is highly flexible, allowing for extension to other structure-determination methods, such as electron microscopy and solid-state NMR spectroscopy. CNS has a hierarchical

AXEL T. BRUNGER; PAUL D. ADAMS; G. MARIUS CLORE; WARREN L. DELANO; PIET GROS; RALF W. GROSSE; JIAN-SHENG JIANG; MICHAEL NILGES; NAVRAJ S. PANNU; RANDY J. READ; LUKE M. RICE; THOMAS SIMONSON; GREGORY L. WARREN; John Kuszewski

1998-01-01

458

NMR study of pore surface and size in the mesoporous material FSM-16  

Microsoft Academic Search

The surface structure, pore size distribution and pore wall thickness of the mesoporous material FSM-16 have been studied by X-ray powder diffraction (XRD), 1H and 29Si MAS NMR and 1H liquid-state NMR, and by applying surface silylation as a probe. The concentrations of surface hydroxyl groups for FSM-16 are estimated from 29Si MAS NMR, and amount to 3×1021 g?1, corresponding

Xiulan Xie; Masatoshi Satozawa; Kimio Kunimori; Shigenobu Hayashi

2000-01-01

459

Comparison of multiple crystal structures with NMR data for engrailed homeodomain  

Microsoft Academic Search

Two methods are currently available to solve high resolution protein structures—X-ray crystallography and nuclear magnetic\\u000a resonance (NMR). Both methods usually produce highly similar structures, but small differences between both solutions are\\u000a always observed. Here the raw NMR data as well as the solved NMR structure were compared to the multiple crystal structures\\u000a solved for the WT 60 residue three helix

Tomasz L. Religa

2008-01-01

460

A Polynomial-Time Nuclear Vector Replacement Algorithm for Automated NMR Resonance Assignments  

Microsoft Academic Search

High-throughput NMR structural biology can play an important role in structural genomics. We report an automated procedure for high-throughput NMR resonance assignment for a protein of known structure, or of a homologous structure. These assignments are a pre- requisite for probing protein-protein interactions, protein-ligand binding, and dynamics by NMR. Assignments are also the starting point for structure determination and refinement.

Christopher James Langmead; Anthony K. Yan; Ryan H. Lilien; Lincong Wang; Bruce Randall Donald

2004-01-01

461

High resolution NMR as a local probe of structure, conformation, and mobility in solid polymers  

NASA Astrophysics Data System (ADS)

Because the NMR frequency of a dipolar nucleus is exquisitely sensitive to the structural and conformational natures of its immediate environment, high resolution NMR can be utilized to probe the structures, conformations, and motions (via resonance relaxation) of the constituent molecules belonging to solid samples. By means of a single polymer example (polypropylene) we attempt to illustrate how structural, conformational, and motional information about solid polymers can be obtained by employing high resolution, solid state NMR.

Tonelli, Alan E.

1995-08-01

462

NMR study of YP and YPO 4 as 2-qubits quantum computers  

Microsoft Academic Search

The 31P-NMR experiments in YP and YPO4 as 2-qubits quantum computers were performed at room temperature under magnetic fields of 6.3 and 11.75 T with a coherent type pulsed FT-NMR spectrometer. The full width at half of the maximum intensity of NMR spectrum for 31P is compared with the second moment caused by the dipolar field. The obtained spin–lattice relaxation times T1 of

H. Kitazawa; K. Hashi; S. Eguchi; T. Shimizu; A. Goto; G. Kido

2002-01-01

463

Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT  

PubMed Central

The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (?H, ?S, and ?G) were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations. PMID:24707291

Bouabdallah, Sondes; Ben Dhia, Med Thaieb; Driss, Med Rida

2014-01-01

464

NMR/NQR and disorder effects in URu2Si2  

NASA Astrophysics Data System (ADS)

NMR experiments at ambient pressure in URu2Si2 demonstrate a linewidth enhancement effect at the hidden order transition temperature (T0). We find that larger amounts of sample disorder appear to induce larger linewidth enhancement at T0. We will present recent NMR and NQR experiments in oriented powder and single crystal samples of URu2Si2 and discuss the measurements with emphasis on a possible connection between linewidth/disorder effects and hidden order. Both NQR and NMR spectra as functions of temperature and NMR for different magnetic field strengths and orientations will be reported.

Bernal, O. O.; Ishida, K.; Reyes, A. P.; Maclaughlin, D. E.; Lukefarh, H. G.; Mydosh, J. A.; Gortenmulder, T. J.; Amitsuka, H.

2005-03-01

465

Nuclear Spin-Lattice Relaxation Times from Continuous Wave NMR Spectroscopy.  

ERIC Educational Resources Information Center

The experiment described, suitable for undergraduate physical chemistry laboratories, illustrates the general principles of relaxation and introduces the nmr concepts of saturation and spin-inversion. (BB)

Wooten, Jan B.; And Others

1979-01-01

466

17O NMR and Raman spectra of water with different calcium salts  

NASA Astrophysics Data System (ADS)

17O NMR and Raman spectra of water with different calcium salts have been measured. Different water samples were prepared by adding nano-materials, calcium gluconate, calcium citrate and calcium chloride into distilled water. Both 17O NMR and Raman spectra of different water samples were recorded. The effects of temperature and time on 17O NMR line-width of different water samples were analyzed as well. The experimental results showed that Raman spectra of water with these four calcium salts were almost the same as those for distilled water when the temperature increased to 40 °C. The 17O NMR line-width of distilled water decreased from 76.8 Hz to 46.9 Hz and 65.8 Hz after nano-materials and calcium chloride were added, respectively. Besides, the 17O NMR line-width of distilled water increased from 76.8 Hz to 131.6 Hz after calcium citrate was added, while the 17O NMR line-width of distilled water increased from 76.8 Hz to 77.2 Hz after calcium gluconate was added. The 17O NMR line-width of water with calcium chloride increased while the other three water samples were nearly stable as the temperature increased from 30 °C to 85 °C. The 17O NMR line-width of water with nano-materials kept steady while the 17O NMR line-width of the other three water samples all increased in 42 days.

Yan, Ying; Ou, Xiao-xia; Zhang, Hui-ping

2014-09-01