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1

Lanthanide-induced phosphorus-31 NMR downfield chemical shifts of lysophosphatidylcholines are sensitive to lysophospholipid critical micelle concentration.  

PubMed Central

Lysophosphatidylcholine (lysoPC) monomers or micelles in water give rise to a narrow, isotropic phosphorus-31 NMR signal (40.6 ppm; v1/2 1.7 Hz; 32.2 MHz). Upon addition of praseodymium ions, the phosphorus signals are shifted downfield. However, the downfield shifts for the longer-chain lysophosphatidylcholines, which exist in the aggregated state, are far greater than those for the shorter-chain homologues, which exist as monomers. At a Pr3+/lysoPC molar ratio of 0.5, the signals of C12lysoPC through C18lysoPC were shifted by 12.1 ppm, whereas the signals of C6lysoPC and C8lysoPC were shifted by only 2.26 ppm. This very pronounced difference in lanthanide-induced downfield shifts between micelles and monomers can be utilized to determine with accuracy lysoPC critical micelle concentrations (CMC) from downfield shift-vs.-concentration plots. The CMC values we determined were 57 mM for C8lysoPC, 5.7 mM for C10lysoPC, and 0.6 mM for C12lysoPC. The shift reagent phosphorus-31 nuclear magnetic resonance technique particularly lends itself to the measurement of CMC values in the millimolar and high micromolar range. The method can equally be used for measuring critical micelle concentrations of short-chain phosphatidylcholines. PMID:2015376

Kumar, V V; Baumann, W J

1991-01-01

2

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

Microsoft Academic Search

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

L. L. Slavin; R. N. Bose

1990-01-01

3

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

SciTech Connect

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

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

1990-12-01

4

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

PubMed

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

Slavin, L L; Bose, R N

1990-12-01

5

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

SciTech Connect

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

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

1997-01-01

6

Hydrolysis of Pyrophosphate in a Highly Calcareous Soil: A Solid-State Phosphorus31 NMR Study  

Microsoft Academic Search

PyrophosphateisthemainformofcondensedPinthefluidfertilizer ammonium polyphosphate (APP). When APP is applied to soil, pyro- phosphate is hydrolyzed to orthophosphate. Hydrolysis of pyrophos- phatewas investigated in a highly calcareous soil over 3 wk. Changes in P speciation were measured using solid-state 31 P nuclear magnetic resonance (NMR) spectroscopy for dried soil samples and ion chro- matography for NaOH extracts. Both techniques showed a decrease

T. M. McBeath; R. J. Smernik; E. Lombi; M. J. McLaughlin

7

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

PubMed Central

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

Thapar, Roopa

2014-01-01

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

Muscle metabolism changes with training in the nonamputated limb after vascular amputation: Interest of phosphorus 31 NMR spectroscopy  

Microsoft Academic Search

Objective: To determine by 31P nuclear magnetic resonance (NMR) spectroscopy the efficacy of training in improving aerobic metabolism of calf muscle in nonamputated limb after recent vascular amputation; to assess the possible associated microcirculatory changes; and to evaluate the need for noninvasive monitoring techniques during training in the nonamputated limb after recent vascular amputation.Design: Prospective study, before and after training.

Veronique Dulieu; Jean-Marie Casillas; Jean-Françis Maillefert; Paul Walker; Yves Cottin; Jean-Pierre Didier; François Brunotte

1997-01-01

10

Phosphorus-31 NMR magnetization transfer measurements of metabolic reaction rates in the rat heart and kidney in vivo  

SciTech Connect

This dissertation is concerned with the measurement of the rates of ATP synthesis in the rat kidney and of the creatine kinase catalyzed reaction in the rat heart in situ. Chronically implanted detection coils, employing a balanced matching configuration of capacitors in the tuned circuit, were used to obtain /sup 31/P NMR spectra from heart, kidney, and liver in situ. Gated spectra of heart obtained at systole and diastole and the effects of fructose on kidney and liver were studied. The ability to observe other nuclei using implanted coils is illustrated with /sup 39/K NMR spectra from kidney and muscle. The theoretical considerations of applying magnetization transfer techniques to intact organs are discussed with emphasis on the problems associated with multiple exchange reactions and compartmentation of reactants. Experimental measurements of the ATP synthesis rate (13 ..mu..mol/min/gm tissue) were compared to whole kidney oxygen consumption and Na/sup +/ reabsorption rates to derive ATP/O (0.8 to 1.7) and Na/sup +//ATP (4 to 10) values. The problems associated with ATP synthesis rate measurements in kidney, e.g., the heterogeneity of the inorganic phosphate resonance, are discussed and experiments to overcome these problems proposed.

Koretsky, A.P.

1984-08-01

11

Phosphorus-31 NMR magnetization transfer measurements of metabolic reaction rates in the rat heart and kidney in vivo  

SciTech Connect

/sup 31/P NMR is a unique tool to study bioenergetics in living cells. The application of magnetization transfer techniques to the measurement of steady-state enzyme reaction rates provides a new approach to understanding the regulation of high energy phosphate metabolism. This dissertation is concerned with the measurement of the rates of ATP synthesis in the rat kidney and of the creatine kinase catalyzed reaction in the rat heart in situ. The theoretical considerations of applying magnetization transfer techniques to intact organs are discussed with emphasis on the problems associated with multiple exchange reactions and compartmentation of reactants. Experimental measurements of the ATP synthesis rate were compared to whole kidney oxygen consumption and Na/sup +/ reabsorption rates to derive ATP/O values. The problems associated with ATP synthesis rate measurements in kidney, e.g. the heterogeneity of the inorganic phosphate resonance, are discussed and experiments to overcome these problems proposed. In heart, the forward rate through creatine kinase was measured to be larger than the reverse rate. To account for the difference in forward and reverse rates a model is proposed based on the compartmentation of a small pool of ATP.

Koretsky, A.P.

1984-01-01

12

Phosphorus-31 two-dimensional solid-state exchange NMR. Application to model membrane and biological systems.  

PubMed Central

Two-dimensional solid-state 31P NMR has been used to investigate the orientational exchange of phospholipids in gel and liquid-crystalline aqueous multilamellar dispersions and oriented multibilayers, and in biological membranes. In liquid-crystalline L alpha multilamellar dispersions, orientational exchange originates from the lateral diffusion of phospholipid molecules over the curved surface of the liposomes and is manifest by an increase in off-diagonal intensity, which correlates the 90 and 0 degrees orientations of the membrane normal with respect to the magnetic field when the system is fully exchanged. Spectral simulations of the time evolution of exchange allowed determination of the correlation times tau d for lateral diffusion. For DMPC and DPPC at comparable reduced temperatures, tau d values of 44 and 8 ms were obtained, respectively. The nature and rate of exchange observed for POPE at 30 degrees C is similar to that of DMPC at the same temperature. The measured correlation times are consistent with diffusion rates obtained by FRAP for liposomes with radii in the 1 micron range. In the gel phase of DPPC (30 degrees C), little orientational exchange is observed at mixing times up to 200 ms, demonstrating that the lateral diffusion is very slow. The correlation time for orientational exchange obtained from spectral simulations was approximately 900 ms; thus, exchange in the gel state is at least two orders of magnitude slower than in the liquid-crystalline state. In the P beta (ripple) phase, at temperatures between 34 and 39 degrees C, significant exchange is observed for mixing times between 50 and 200 ms. Exchange is also observed in oriented samples of DPPC in the P beta phase for mixing times of 50 ms, but not for oriented liquid-crystalline samples for mixing times up to 100 ms. The exchange observed in the ripple phase could originate from rapid lateral diffusion of "fast" diffusing phospholipid within defect structures, and/or from "slow" lateral diffusion of ordered phospholipid over the ripples. 2D experiments were also performed on pig erythrocyte ghosts and on intact pig spinal cord. Significant orientational exchange was observed with the erythrocyte ghosts at a mixing time of 200 ms, but almost no exchange was observed with the spinal cord at the same mixing time. Spectral simulations suggest tau d values of approximately 400 ms and 1.3 s for the erythrocyte ghosts and spinal cord at 30 degrees C. The results demonstrate that exchange in the biological membranes is significantly slower than in the model membrane systems, which suggests that the cell surfaces are relatively "smooth," i.e., any local surface perturbations are either present in small number or have little effect on the mean orientation of the phospholipids with respect to the membrane normal. PMID:2015390

Fenske, D. B.; Jarrell, H. C.

1991-01-01

13

Phosphorus-31 magnetic relaxation of phosphocreatine in solution  

NASA Astrophysics Data System (ADS)

Measurements have been made of the longitudinal phosphorus-31 magnetic relaxation of phosphocreatine in H 2O and D 2O solutions from 278 to 333 K at 121.5 and at 40.5 MHz. The phosphorus-31 spin—lattice relaxation of phosphocreatine is dominated by intermolecular and intramolecular dipolar and chemical-shift anisotropy interactions. The relative contribution of the two interactions to the spin—lattice relaxation changes with NMR frequency. Activation energies characterizing the solution dynamics of the phosphocreatine molecule in H 2O and D 2O are 15.4±1.1 and 14.6±1.0 kJ/mol, respectively.

Gaspar, R., Jr.; Brey, W. S.; Andrew, E. R.

1991-09-01

14

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

15

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

E-print Network

with aluminum- and iron hydroxides, and phytic acid (inositol hexakisphosphate). Solution 31 P-NMR spectroscopy1617 The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [31 P-NMR that receive alum (aluminum sulfate) to reduce water-soluble P and control ammonia emissions from poultry

Sparks, Donald L.

16

Phosphorus-31 nuclear magnetic resonance studies of spermatozoa from the boar, ram, goat and bull.  

PubMed

1. Phosphorus-31 nuclear magnetic resonance spectroscopy (31P-NMR) was utilized to examine semen and spermatozoa isolated from boars, rams, goats and bulls. 2. Whole semen was found to contain high but variable levels of glycerylphosphocholine, most of which was located in the seminal plasma rather than in the spermatozoa. 3. Spermatozoa concentrated into a pellet were found to contain resonances for inorganic phosphate, phosphomonoesters including fructose-1,6-bisphosphate and glucose-6-phosphate, and free nucleotide triphosphate peaks. 4. A broad resonance was observed from 30 to -25 ppm which originated partly from nucleotide tri- and diphosphates. 5. No high energy molecules such as phosphoarginine or phosphocreatine which could act as energy shuttles were observed. PMID:3621898

Robitaille, P M; Robitaille, P A; Martin, P A; Brown, G G

1987-01-01

17

Phosphorus-31 Fourier transform nuclear magnetic resonance study of mononucleotides and dinucleotides. 2. Coupling constants.  

PubMed

Stereosensitive 3JPH and 4JPH phosphorus-proton coupling constants have been measured directly from the phosphorus-31 nuclear magnetic resonance (NMR) spectra of a variety of adenine, thymine, and uracil 3'-mononucleotides, 5'-mononucleotides, their cyclic analogues, and the corresponding dinucleotides, under various conditions of pH and temperature. For all 5'-mononucleotides, the identical 3JPH coupling to phosphorus of the two H5' protons is found essentially independent of the nature of the base, the presence of a 2'-OH on the sugar ring, the temperature, and the pH; the "gauche-gauche" rotamers about C5'-O5' and C4'-C5' remain overwhelmingly (85%) preferred. The "gauche" arrangement during C3'-O3' is favored in all cases for 3'-mononucleotides. However, while no sizeable pH effect is noted on 3'-monodeoxyribonucleotides, the pH dependence of 3JPH3 in 3'-monoribonucleotides strongly suggests an interaction between the 3'-phosphate and the 2'-OH. Molecular features affecting the magnitude of 4JPH coupling constants are discussed together with pH and temperature effects. The time-averaged preferential structural features of mononucleotides are found in dinucleotides with a higher probability; hence, dimerization induces an increase in the statistical conformational purity of the phosphodiester-sugar backbone, even at extreme pH. Temperature studies point out that the thermal unwinding of stacked dinucleotides occurs mainly via rotation about P3'-O3' and P5'-O5' bond axes. PMID:990248

Cozzone, P J; Jardetzky, O

1976-11-01

18

A conformational study of nucleic acid phosphate ester bonds using phosphorus-31 nuclear magnetic resonance.  

PubMed Central

A systematic phosphorus-31 nuclear magnetic resonance study of some nucleic acid constituents (6-N-(dimethyl)adenylyl-(3',5')-uridine and some nucleotide methyl esters) is presented. The temperature dependent phosphorus-31 chemical shifts were analyzed by standard thermodynamic procedures. It is shown that gt conformations about the P-O ester bonds have a lower free energy content relative to gg conformers. PMID:440971

Haasnoot, C A; Altona, C

1979-01-01

19

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.; Jensen, Paul

1989-01-01

20

One-dimensional phosphorus-31 chemical shift imaging of human brain tumors  

SciTech Connect

Phosphorus magnetic resonance spectroscopy has been used noninvasively to determine characteristic spectral parameters for untreated human brain tumors as a prelude to its use in clinical diagnosis. The spectra, which reflect the relative amounts of phosphorus-containing compounds, and the pH within and surrounding the tumors, were obtained in vivo using the the localization technique of one-dimensional chemical shift imaging applied with a surface coil. Phosphorus-31 chemical shift imaging was performed successfully in vivo on 9 volunteers and 27 patients with untreated brain tumors, including 7 with astrocytoma, 4 with glioblastoma, 3 with meningioma, and 11 with metastases. This study provides spectra from within and surrounding the brain tumors, and allows accountability for the heterogeneity of brain tumors by the selection of the maximum data point for each parameter. The ratios of resonance areas, phosphodiesters over nucleoside triphosphate (NTP), and phosphomonoesters over NTP, were found to be higher in glioblastomas (2.55 {plus_minus} 0.22, 1.06 {plus_minus} 0.09) and astorcytomas (3.04 {plus_minus} 0.36, 1.28 {plus_minus} 0.36) than in normal brain (2.00 {plus_minus} 0.32, 0.79 {plus_minus}0.22). The ratios of areas due to inorganic phosphate and NTP, and phosphocreatine and NTP, also were higher in astrocytomas (1.16 {plus_minus} 0.40, 1.17 {plus_minus} 0.41) compared with glioblastomas (0.68 {plus_minus} 0.01, 0.88 {plus_minus} 0.19) and normal brain (0.61 {plus_minus}0.03, 0.77 {plus_minus} 0.03). The pH of brain tumors ranged from alkaline to neutral, with meningiomas consistently having alkaline pH. These data show that there are statistically significant differences in the magnetic resonance parameters of the affected brain hemispheres of patients with astrocytomas, glioblastomas, meningiomas, and normal brain tissue, and underline the need for a multisite clinical trial to establish clinical criteria for diagnosis. 28 refs., 3 figs., 2 tabs.

Rutter, A. [Univ. of Sydney (Australia); Hugenholtz, H. [Ottawa General Hospital, Ontario (Canada); Saunders, J.K. [Inst. for Biodiagnostics, Winnipeg (Canada)] [and others

1995-06-01

21

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

SciTech Connect

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

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

1988-01-01

22

Composition of aluminum phosphate solutions. Evidence from aluminum-27 and phosphorus-31 nuclear magnetic resonance spectra  

Microsoft Academic Search

Low- (2.11 T) and high-field (9.4 T) ²⁷Al and ³¹P nuclear magnetic resonance (NMR) spectrometry has been used to study the structure and reactivity of aluminum chloride solutions in the presence and absence of OH⁻, HâPOâ, HâPOâ⁻, HPOâ²⁻, and POâ³⁻ species. Evidence is presented for the existence of higher molecular weight complexes than the (AlOâAlââ(OH)ââ(HâO)ââ){sup 7+} cation in the presence

Michael A. Wilson; Philip J. Collin; J. W. Akitt

1989-01-01

23

Phosphorus-31 nuclear magnetic resonance spectroscopy transect study of poultry operations on the Delmarva Peninsula.  

PubMed

Nonpoint source phosphorus (P) pollution into the Chesapeake Bay watershed from poultry operations contributes to the algal blooms, hypoxia, anoxia, and fish kill events that occur there most years. A major source of soluble, bioavailable P species is poultry litter, which is used as a crop fertilizer on fields adjacent to the tributaries of the Bay. A potentially significant source of orthophosphate in the litter is the heavily phosphorylated compound myo-inositol hexakisphosphate (phytate), which is indigestible by poultry and thus becomes a major component of their excreta. Phytate evaluation in environmental samples is expensive; hence, its impact is not captured in standard farmer-friendly eutrophication potential guides, like Delaware's Phosphorus Site Index. In this transect study of two poultry operations on the Delmarva Peninsula, we measured the incidence of all P compounds using solution 31P nuclear magnetic resonance (NMR) spectroscopy and extracts, relating them to relevant geochemical properties. The contribution of phytate to the overall pool of P declined from around 50% in manures to between 2 and 13% in down-gradient soils and sediments, corresponding to a rise in the relative proportion of orthophosphate (increasing from 39% to 65-88%). The results show that the large pool of phytate P spread onto croplands during standard operating practice at poultry farms on the Delmarva Peninsula does not appear to accumulate; rather, phytate decreases in down-gradient locations, most likely due to transport off-site and/or through in situ biological activity. PMID:19141802

Hill, Jane E; Cade-Menun, Barbara J

2009-01-01

24

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

25

Phosphorus-31 nuclear magnetic resonance study of internal motion in ribonucleic acid of southern bean mosaic virus.  

PubMed

Phosphorus-31 nuclear magnetic resonance spectroscopy was used to study southern bean mosaic virus (SBMV) in its native and ethylenediaminetetraacetic acid treated forms at various pH values in the range 4.5-9.0. The degree of swelling in the latter form is a critical function of pH. Spin-lattice relaxation time (T1), line-width, and nuclear Overhauser effect (NOE) measurements were made at 40.51, 80.98, and 190.3 MHz. The results indicate that the RNA phosphate groups in native SBMV exhibit low-amplitude internal motions on a nanosecond time scale while the phosphate groups of swollen virus exhibit large-amplitude, more rapid, internal motions. A spread of T1 and NOE values is measured at intermediate stages in the swelling process. A simple explanation, consistent with the data, is that the RNA core of the virus undergoes a two-state phase transition from a relatively rigid, compact solid form in the native SBMV to a mobile, solvated state in the fully swollen particle. PMID:6816273

McCain, D C; Virudachalam, R; Santini, R E; Abdel-Meguid, S S; Markley, J L

1982-10-26

26

Positron emission tomography of fluorine-18-deoxyglucose and image-guided phosphorus-31 magnetic resonance spectroscopy in brain tumors  

SciTech Connect

Positron emission tomography (PET) of 2(18F)-fluoro-2-deoxy-D-glucose (FDG) and volume-selective phosphorus-31 magnetic resonance spectroscopy (31P-MRS) are methods used to assess the energy metabolism of the brain. Both methods were studied with respect to their contribution to differential diagnosis in 23 patients with various brain tumors. The various neuroectodermal tumors differed with respect to their metabolic rate for glucose (MRGL). Benign and malignant tumors could be better differentiated by using tumor metabolism relative to contralateral brain and by evaluating heterogeneities in tumors. Low-grade gliomas usually showed normal 31P-MR spectra; high-grade gliomas were characterized by reduced and often split phosphodiester peaks and alkaline pH. Meningiomas, which had variable MRGL, typically showed extremely low phosphocreatine levels, reduced phosphodiesters, and alkaline pH. We concluded that FDG-PET and 31P-MRS examine different aspects of tumor metabolism. Therefore, both can contribute independently and complementarily to the differential diagnosis of brain tumors.

Heiss, W.D.; Heindel, W.; Herholz, K.; Rudolf, J.; Bunke, J.; Jeske, J.; Friedmann, G. (Universitaet zu Koeln (Germany, F.R.))

1990-03-01

27

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

28

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

29

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

30

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

SciTech Connect

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

Gard, J.K.

1984-01-01

31

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

SciTech Connect

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

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

1988-05-01

32

31P and 27Al NMR studies of aqueous (2-hydroxyethyl) trimethylammonium solutions containing aluminum and phosphorus  

Microsoft Academic Search

Phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques have been used to characterize the distribution of soluble aluminophosphate species in aqueous solutions of (2-hydroxyethyl) trimethylammonium chloride (2-HETMACl), phosphoric acid, and aluminum sulfate. Soluble aluminophosphate cations obtain from reactions of hexaaqua aluminum cations [A1(H2O)6]3+, with phosphate ligands (i.e., H3PO4, H2PO4–, and acid dimers H6P2O8 and H5P2O7–). 31P NMR and 27Al NMR spectroscopies

Abdolraouf Samadi-Maybodi; S. Karim Hassani Nejad-Darzi; Hamidreza Bijanzadeh

2009-01-01

33

Phosphorus forms and chemistry in the soil profile under long-term conservation tillage: a phosphorus-31 nuclear magnetic resonance study.  

PubMed

In many regions, conservation tillage has replaced conventional tilling practices to reduce soil erosion, improve water conservation, and increase soil organic matter. However, tillage can have marked effects on soil properties, specifically nutrient redistribution or stratification in the soil profile. The objective of this research was to examine soil phosphorus (P) forms and concentrations in a long-term study comparing conservation tillage (direct drilling, "No Till") and conventional tillage (moldboard plowing to 20 cm depth, "Till") established on a fine sandy loam (Orthic Humo-Ferric Podzol) in Prince Edward Island, Canada. No significant differences in total carbon (C), total nitrogen (N), total P, or total organic P concentrations were detected between the tillage systems at any depth in the 0- to 60-cm depth range analyzed. However, analysis with phosphorus-31 nuclear magnetic resonance spectroscopy showed differences in P forms in the plow layer. In particular, the concentration of orthophosphate was significantly higher under No Till than Till at 5 to 10 cm, but the reverse was true at 10 to 20 cm. Mehlich 3-extractable P was also significantly higher in No Till at 5 to 10 cm and significantly higher in Till at 20 to 30 cm. This P stratification appears to be caused by a lack of mixing of applied fertilizer in No Till because the same trends were observed for pH and Mehlich 3-extractable Ca (significantly higher in the Till treatment at 20 to 30 cm), reflecting mixing of applied lime. The P saturation ratio was significantly higher under No Till at 0 to 5 cm and exceeded the recommended limits, suggesting that P stratification under No Till had increased the potential for P loss in runoff from these sites. PMID:21043270

Cade-Menun, Barbara J; Carter, Martin R; James, Dean C; Liu, Corey W

2010-01-01

34

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

2008-03-25

35

Depletion of high-energy phosphates in the central nervous system of patients with systemic lupus erythematosus, as determined by phosphorus-31 nuclear magnetic resonance spectroscopy.  

PubMed

Systemic lupus erythematosus (SLE) can produce profound disturbances in the central nervous system, characterized by encephalopathy, focal neurologic deficits, cerebral infarction, psychosis, and seizures. We used 31P nuclear magnetic resonance (NMR) spectroscopy to determine the in vivo levels of high-energy phosphates in the central nervous system of 10 patients with SLE and 10 age-matched normal controls. 31P NMR spectroscopy was performed on a 1.5-Tesla unit equipped with a dual-tuned 1H-31P surface coil and a software-directed DRESS (depth resolved surface coil spectroscopy) pulse sequence. This procedure detected ADP, ATP, sugar phosphates, phosphocreatine (PCr), inorganic phosphate, phosphomonoesters, and phosphodiesters in the brain tissue of all study subjects. Levels of ATP in the deep white matter of 10 SLE patients were significantly decreased compared with the levels in 10 normal controls, as quantitated by the ratio of ATP:ATP + ADP (mean +/- SD 0.81 +/- 0.11 versus 0.91 +/- 0.05; P less than 0.02). In a subgroup of 4 patients, PCr levels were decreased to a greater extent than the ATP levels. NMR spectroscopic alterations were not related to obvious anatomic lesions, as determined by standard cranial proton magnetic resonance imaging. In 4 SLE patients with markedly abnormal 31P NMR spectra, treatment with prednisone (80 mg/day) normalized the levels of ATP and PCr. Restoration of a normal 31P profile was accompanied by an obvious improvement in the patients' mental status and clinical symptoms. 31P NMR spectroscopy is a powerful new technique for monitoring high-energy phosphate metabolism, and may be particularly useful for characterizing central nervous system disease in patients with neuropsychiatric SLE. PMID:2363738

Griffey, R H; Brown, M S; Bankhurst, A D; Sibbitt, R R; Sibbitt, W L

1990-06-01

36

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

37

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

38

Enantiomeric differentiation of oxygenated p-menthane derivatives by 13C NMR using Yb(hfc)3.  

PubMed

The (13)C NMR behaviour of 21 p-menthanic terpene bearing an oxygenated function (alcohol, ketone, acetate) was examined in the presence of a chiral lanthanide shift reagent (Yb(hfc)(3)). For each monocyclic compound, we measured the lanthanide-induced shift (LIS) on the signals of the carbons and the splitting of signals allowing the enantiomeric differentiation. Some general features were found about their LIS behaviour: experimental data establishing distinct patterns for carvomenthone-like compounds and menthone-like compounds. The enantiomeric splitting was observed for the majority of signals in the spectrum of each compound. In the case of alcohols and acetates, the influence of the relative stereochemistry (cis vs trans) of isopropyl(ene) and the binding function was discussed. PMID:18828150

Lanfranchi, Don Antoine; Blanc, Marie-Cécile; Vellutini, Muriel; Bradesi, Pascale; Casanova, Joseph; Tomi, Félix

2008-12-01

39

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

40

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

41

(31)P and (27)Al NMR studies of aqueous (2-hydroxyethyl) trimethylammonium solutions containing aluminum and phosphorus.  

PubMed

Phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques have been used to characterize the distribution of soluble aluminophosphate species in aqueous solutions of (2-hydroxyethyl) trimethylammonium chloride (2-HETMACl), phosphoric acid, and aluminum sulfate. Soluble aluminophosphate cations obtain from reactions of hexaaqua aluminum cations [A1(H(2)O)(6)](3+), with phosphate ligands (i.e., H(3)PO(4), H(2)PO(4)(-), and acid dimers H(6)P(2)O(8) and H(5)P(2)O(7)(-)). (31)P NMR and (27)Al NMR spectroscopies are very powerful techniques for characterization of the species present in the solution. A number of solutions containing different mole ratio of Al/P were prepared. The assignment of the peaks to aluminate connectivities is attempted, clarifying earlier works and producing information on the equilibrium between various aluminum-containing species (different aluminophosphate complexes). At least seven separated resonances were observed by (31)P NMR spectroscopy indicating presence of different complexes in aluminum phosphate solutions. PMID:19041278

Samadi-Maybodi, Abdolraouf; Nejad-Darzi, S Karim Hassani; Bijanzadeh, Hamidreza

2009-03-01

42

Temperature-reversible eruptions of vesicles in model membranes studied by NMR.  

PubMed Central

Deuterium (2H) and phosphorus (31P) nuclear magnetic resonance (NMR) and freeze-fracture electron microscopy were used to study spontaneous vesiculation in model membranes composed of POPC:POPS with or without cholesterol. The NMR spectra indicated the presence of a central isotropic line, the intensity of which is reversibly and linearly dependent upon temperature in the L alpha phase, with no hysteresis when cycling between higher and lower temperatures. Freeze-fracture microscopy showed small, apparently connected vesicles that were only present when the samples were frozen (for freeze-fracture) from an initial temperature of 40-60 degrees C, and absent when the samples are frozen from an initial temperature of 20 degrees C. Analysis of motional narrowing was consistent with the isotropic lines being due to lateral diffusion in (and tumbling of) small vesicles (diameters approximately 50 nm). These results were interpreted in terms of current theories of shape fluctuations in large unilamellar vesicles which predict that small daughter vesicles may spontaneously "erupt" from larger parent vesicles in order to expel the excess area created by thermal expansion of the bilayer surface at constant volume. Assuming that all the increased area due to increasing temperature is associated with the isotropic lines, the NMR results allowed a novel estimate of the coefficient of area expansion alpha A in multilamellar vesicles (MLVs) which is in good agreement with micromechanical measurements upon giant unilamellar vesicles of similar composition. Experiments performed on unilamellar vesicles, which had been placed upon glass beads, confirmed that alpha A determined in this way is unchanged compared with the MLV case. Addition of the highly positively charged (extrinsic) myelin basic protein (MBP) to a POPC:POPS system showed that membrane eruptions of the type described here occur in response to the presence of this protein. Images FIGURE 5 FIGURE 5 FIGURE 5 FIGURE 6 PMID:1600085

Nezil, F A; Bayerl, S; Bloom, M

1992-01-01

43

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

44

Nmr in drug discovery  

Microsoft Academic Search

NMR spectroscopy has evolved into an important technique in support of structure-based drug design. Here, we survey the principles that enable NMR to provide information on the nature of molecular interactions and, on this basis, we discuss current NMR-based strategies that can identify weak-binding compounds and aid their development into potent, drug-like inhibitors for use as lead compounds in drug

Maurizio Pellecchia; Daniel S. Sem; Kurt Wüthrich

2002-01-01

45

Small NMR biomolecular sensors  

NASA Astrophysics Data System (ADS)

By combining the physics of nuclear magnetic resonance (NMR) and silicon radio-frequency (RF) integrated circuits, we recently created progressively smaller NMR systems, which we originally reported in Refs. [1-4]. Our strategy for NMR system miniaturization proved effective, culminating in the smallest prototype [3,4] that weighs 0.1 kg and can be held at the palm of the hand. These small, low-cost NMR systems can be useful as biomolecular sensors in the personalized medicine setting, and we demonstrated their ability to detect proteins, compounds, and human cancer cells. The present paper, which is not a new technical contribution, reviews these developments.

Sun, Nan; Liu, Yong; Qin, Ling; Lee, Hakho; Weissleder, Ralph; Ham, Donhee

2013-06-01

46

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

47

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

48

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

49

Lectures on pulsed NMR  

SciTech Connect

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

Pines, A.

1986-09-01

50

Basics of NMR  

NSDL National Science Digital Library

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

Hornak, Joseph P.

2005-10-31

51

Silver and gold NMR.  

PubMed

Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope ((197)Au), which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms ((109)Ag and (109)Au), both of which have a spin 1/2 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on (109)Ag. PMID:18475898

Zangger, K; Armitage, L M

1999-01-01

52

(29)Si NMR in LC-NMR analysis of silicones.  

PubMed

It is demonstrated using a practical example that indirect detection of (29)Si NMR signals is sufficiently sensitive in LC-NMR stop-flow arrangement to analyze mixtures of siloxane polymers. New cryogenic probes with better signal-to-noise ratio will turn this version of LC-NMR into a routine method for analysis of siloxane polymers. PMID:16261506

Blechta, Vratislav; Sýkora, Jan; Hetflejs, Jirí; Sabata, Stanislav; Schraml, Jan

2006-01-01

53

Advanced NMR Studies of Fluoropolymers.  

E-print Network

??The advanced NMR studies of fluoropolymers are focused on the Krytox® poly-(hexafluoropropylene oxide) (PHFPO) and poly(1-chloro-1-fluoroethylene) (PCFE). 2D NMR techniques were used to study the… (more)

Li, Xiaohong

2011-01-01

54

NMR planar microcoil for microanalysis  

Microsoft Academic Search

This article deals with the analysis of small sample volume by using a planar microcoil and a micromachined cavity. This microcoil is used as a nuclear magnetic resonance (NMR) radio frequency detection coil in order to perform in vitro NMR analysis of the sample introduced into the microcavity. It is a real challenging task to develop microsystem for NMR spectrum

B. Sorli; J. F. Chateaux; L. Quiquerez; L. Bouchet-Fakri; A. Briguet; P. Morin

2006-01-01

55

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

56

Phosphorous NMR in biology  

SciTech Connect

This book reviews the technique of phosphorous NMR and its relationship to every existing level of biology and biochemistry. The bulk of the book is broken into three sections: simple biomolecules; macromolecules/macromolecular assemblages; and complex systems necessary to maintain life. Topics include: relaxation time of inorganic phosphate, behavior of ATP with biological molecules and characterization of t-RNA.

Burt, C.T.

1987-01-01

57

Modern NMR Spectroscopy.  

ERIC Educational Resources Information Center

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

Jelinski, Lynn W.

1984-01-01

58

?- NMR of Palladium foil  

NASA Astrophysics Data System (ADS)

Beta-detected NMR ( ?- NMR) of low-energy implanted 8Li + was studied in metallic palladium. The resonance was found to have a large negative shift with respect to the reference signal in the cubic insulator MgO. This shift exhibited significant temperature dependence on cooling below room temperature, approximately proportionate to the temperature-dependent spin susceptibility of pure Pd. Thus it is tentatively attributed to a Knight shift ( K) caused by a large negative hyperfine coupling; a phenomenon common in transition metal ions, but not in alkalis. However, the spin-lattice relaxation of 8Li is much slower than expected from the Korringa law for such a large K. We compare results from samples of very different thicknesses: 12.5 ?m foil and a 100 nm thin film.

Parolin, T. J.; Salman, Z.; Chakhalian, J.; Wang, D.; Keeler, T. A.; Hossain, Md.; Kiefl, R. F.; Chow, K. H.; Morris, G. D.; Miller, R. I.; MacFarlane, W. A.

2006-03-01

59

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

60

NMR at low magnetic fields  

NASA Astrophysics Data System (ADS)

NMR provides outstanding information in chemistry and in medicine. But the equipment is expensive as high-field magnets are employed. Low-field NMR works with inexpensive permanent magnets. Until recently these did not provide fields sufficiently homogeneous for spectroscopy and were mostly used for relaxation measurements. Relaxation can also be measured outside the magnet, and small mobile NMR devices have been developed for non-destructive testing of large objects. Today small stray-field magnets and small magnets with homogeneous fields are available for relaxation analysis, imaging, and spectroscopy. Their availability is believed to be essential for shifting NMR analysis from a specialist's tool to a convenience tool.

Blümich, Bernhard; Casanova, Federico; Appelt, Stephan

2009-08-01

61

NMR properties of sedimented solutes.  

PubMed

This perspective paper is intended to give some insights into the recently proposed technique of NMR of solutes sedimented by ultracentrifugation in a rotor used for solid state NMR experiments. Sedimented "states" correspond to molecules with very little reorientational capability in extremely concentrated solutions. They provide solid state NMR spectra comparable in quality with those of the best microcrystalline samples. Here we report some experiments to look for chemicals which affect the properties of the sediment, and we show that it is possible to fill the rotor in a true ultracentrifuge and then record the spectra. The latter possibility opens new horizons for NMR of sedimented systems. PMID:22120590

Bertini, Ivano; Engelke, Frank; Luchinat, Claudio; Parigi, Giacomo; Ravera, Enrico; Rosa, Camilla; Turano, Paola

2012-01-14

62

THz Dynamic Nuclear Polarization NMR  

PubMed Central

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

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

2013-01-01

63

NMR measurement of pore structure  

SciTech Connect

An attempt was made to pursue [sup 129]Xe NMR as a pore measurement technique. Samples studied were synthetic imogolite (tubular aluminosilicate with gibbsite structure), sodium Y-zeolite, and an aerogel and a xerogel. Gases used were normal Xe, [sup 13]CO[sub 2], and [sup 15]N[sub 2]. Although a completely general NMR technique for measuring pore size distributions may not be possible, information about molecular motion and interactions can be obtained, because NMR is sensitive to short range interactions (1 nm or less) and to molecular dynamics in the range 10[sup [minus]2] to 10[sup [minus]6]s.

Earl, W.L. (Los Alamos National Lab., NM (United States)); Kim, Yong-Wah (Los Alamos National Lab., NM (United States) New Mexico Univ., Albuquerque, NM (United States). Center for Microengineered Ceramics); Smith, D.M. (New Mexico Univ., Albuquerque, NM (United States). Center for Microengineered Ceramics)

1993-05-31

64

NMR measurement of pore structure  

SciTech Connect

An attempt was made to pursue {sup 129}Xe NMR as a pore measurement technique. Samples studied were synthetic imogolite (tubular aluminosilicate with gibbsite structure), sodium Y-zeolite, and an aerogel and a xerogel. Gases used were normal Xe, {sup 13}CO{sub 2}, and {sup 15}N{sub 2}. Although a completely general NMR technique for measuring pore size distributions may not be possible, information about molecular motion and interactions can be obtained, because NMR is sensitive to short range interactions (1 nm or less) and to molecular dynamics in the range 10{sup {minus}2} to 10{sup {minus}6}s.

Earl, W.L. [Los Alamos National Lab., NM (United States); Kim, Yong-Wah [Los Alamos National Lab., NM (United States)]|[New Mexico Univ., Albuquerque, NM (United States). Center for Microengineered Ceramics; Smith, D.M. [New Mexico Univ., Albuquerque, NM (United States). Center for Microengineered Ceramics

1993-05-31

65

Transformer-coupled NMR probe  

NASA Astrophysics Data System (ADS)

In this study, we propose an NMR probe circuit that uses a transformer with a ferromagnetic core for impedance matching. The ferromagnetic core provides a strong but confined coupling that result in efficient energy transfer between the sample coil and NMR spectrometer, while not disturbing the B1 field generated by the sample coil. We built a transformer-coupled NMR probe and found that it offers comparable performance (loss <1 dB) to a conventional capacitor-coupled circuit. Our probe operates over a wide frequency range (500 kHz-5 MHz in this example) without the need for matching adjustments. Such probes could be useful for low-field mobile NMR applications of multi-frequency operation, such as imaging, relaxation, and diffusion measurements, as well as NQR.

Utsuzawa, Shin; Mandal, Soumyajit; Song, Yi-Qiao

2012-03-01

66

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

67

Compact orthogonal NMR field sensor  

DOEpatents

A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL)

2009-02-03

68

Optical pumping and xenon NMR  

SciTech Connect

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

Raftery, M.D.

1991-11-01

69

Optical pumping and xenon NMR  

SciTech Connect

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

Raftery, M.D.

1991-11-01

70

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

71

NMR studies of some rifamycins  

NASA Astrophysics Data System (ADS)

The 13C and 1H NMR spectra of rifabutin 1 and five of its derivatives 2- 6, three of which are described for the first time, were assigned using 2D homo- and heteronuclear correlation NMR spectroscopy, proton exchange with deuterium, and selective proton decoupling methods to one bond and long distance. The study was also extended to the other well-known ansamycin antibiotics, rifamycin S 7 and rifampicin 8. Previous interpretations for the known compounds have been corrected.

Santos, L.; Medeiros, M. A.; Santos, S.; Costa, M. C.; Tavares, R.; Curto, M. J. M.

2001-05-01

72

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

73

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

74

Solid-State NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

Due to the development of new techniques and further increase of magnetic field strength available for commercial applications, solid-state NMR spectroscopy became a routine method for the characterization of zeolites. As an important advantage, solid-state NMR spectroscopy allows the investigation of the local structure of nuclei in the solids under study. The specific behavior of zeolites often depends on local effects, such as framework defects, the substitution of framework atoms, guest compounds etc. Therefore, solid-state NMR spectroscopy is a widely applied analytical method for delivering structure data, which are complementary to those of diffraction methods suitable for investigating the long-range order. While early solid-state NMR spectroscopic studies often focused on the characterization of the zeolite framework in the as-synthesized and hydrated state, an increasing number of recent works is dealing with the investigation of the framework of dehydrated and calcined zeolites and of surface sites, i.e., on the determination of their concentration, strength, and accessibility. In all these applications, the advantage of solid-state NMR spectroscopy to be a quantitative method is utilized. The present chapter demonstrates the fundamentals, various techniques, and most important applications of solid-state NMR spectroscopy making this method to an important tool of research in zeolite science.

Hunger, Michael

75

NMR Relaxation and Petrophysical Properties  

NASA Astrophysics Data System (ADS)

NMR relaxation is routinely used in the field of geosciences to give basic petrophysical properties such as porosity, pore size distribution, saturation etc. In this tutorial, we focus on the pore size distribution deduced from NMR. We recall the basic principle used in the interpretation of the NMR signal and compare the results with other standard petrophysical techniques such as mercury pore size distribution, BET specific surface measurements, thin section visualizations. The NMR pore size distribution is a unique information available on water saturated porous media and can give similar results as MICP in certain situations. The scaling of NMR relaxation time distribution (s) into pore sizes (?m) requires the knowledge of the surface relaxivity (?m/s) and we recommend using specific surface measurements as an independent determination of solid surface areas. With usual surface relaxivities, the NMR technique can explore length-scales starting from nano-meters and ending around 100 ?m. Finally, we will introduce briefly recent techniques sensitive to the pore to pore diffusional exchange, providing new information on the connectivity of the pore network, but showing another possibility of discrepancy in the determination of pore size distribution with standard techniques.

Fleury, Marc

2011-03-01

76

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

77

NMR planar microcoil for microanalysis  

NASA Astrophysics Data System (ADS)

This article deals with the analysis of small sample volume by using a planar microcoil and a micromachined cavity. This microcoil is used as a nuclear magnetic resonance (NMR) radio frequency detection coil in order to perform in vitro NMR analysis of the sample introduced into the microcavity. It is a real challenging task to develop microsystem for NMR spectrum extraction for smaller and smaller sample volume. Moreover, it is advantageous that these microsystems could be integrated in a Micro Total Analysing System (? -TAS) as an analysing tool. In this paper, NMR theory, description, fabrication process and electrical characterization of planar microcoils receiver are described. Results obtained on NMR microspectroscopy experiments have been performed on water and ethanol, using a 1 mm diameter planar coil. This microcoil is tuned and matched at 85.13 MHz which is the Larmor frequency of proton in a 2 T magnetic field. This paper has been presented at “3e colloque interdisciplinaire en instrumentation (C2I 2004)”, École Normale Supérieure de Cachan, 29 30 janvier 2004.

Sorli, B.; Chateaux, J. F.; Quiquerez, L.; Bouchet-Fakri, L.; Briguet, A.; Morin, P.

2006-11-01

78

"Solvent Effects" in 1H NMR Spectroscopy.  

ERIC Educational Resources Information Center

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

Cavaleiro, Jose A. S.

1987-01-01

79

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

80

?-NMR of a thin Pt film  

NASA Astrophysics Data System (ADS)

We report beta-detected NMR ( ?-NMR) measurements on a 50 nm thick platinum (Pt) film grown on a magnesium oxide (MgO) substrate. The frequency of the ?-NMR resonance in Pt was compared to the MgO reference frequency to estimate the Knight shift at various temperatures (100-300 K). The Knight shift was found to be negative and strongly temperature dependent. The implications are discussed and compared to other transition metals that have been studied via ?-NMR previously.

Fan, I.; Chow, K. H.; Parolin, T. J.; Egilmez, M.; Hossain, M. D.; Jung, J.; Keeler, T. A.; Kiefl, R. F.; Kreitzman, S. R.; Levy, C. D. P.; Ma, R.; Morris, G. D.; Pearson, M. R.; Saadaoui, H.; Salman, Z.; Smadella, M.; Song, Q.; Wang, D.; Xu, M.; MacFarlane, W. A.

2009-04-01

81

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...

82

NMR properties of alginate microbeads  

Microsoft Academic Search

Alginates are a family of unbranched polysaccharides with properties that vary widely depending on their composition. In the presence of multivalent cations (frequently Ca2+), alginates form a gel. Consequently, alginates have been used to encapsulate a variety of biological materials, including cells. In this study, we present NMR relaxation and diffusion data from alginate microbeads with similar size and properties

Nicholas E. Simpson; Samuel C. Grant; Stephen J. Blackband; Ioannis Constantinidis

2003-01-01

83

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

84

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

Microsoft Academic Search

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 13C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was

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

2004-01-01

85

Solid-state distortions of nominally square-planar palladium and platinum (R sub 3 P) sub 2 MX sub 2 complexes as determined by a combination of sup 13 C( sup 1 H) and sup 31 P( sup 31 H) NMR spectroscopy  

SciTech Connect

Phosphorus-31 and carbon-13 NMR spectra have been obtained for a series of 20 (R{sub 3}P){sub 2}MX{sub 2} complexes (R{sub 3}P = MePh{sub 2}P and Me{sub 2}PhP; M = Pd, Pt; X = Cl, Br, I, CN, N{sub 3}) in the solid state by cross-polarization and magic-angle-spinning (CP/MAS) techniques. Comparison of these data with spectral data obtained at 300 K in CDCl{sub 3} solutions was made in order to investigate the influence of local symmetry on {sup 31}P and {sup 13}C chemical shifts in the solid state. It was found that most of these compounds, which have regular square-planar geometries in solution, are distorted in the solid state. The solid-state distortions are evidenced by additional {sup 31}P and {sup 13}C resonances in the CP/MAS spectra as compared to the solution spectra. The nature and degree of these distortions are discussed. 25 refs., 2 figs., 6 tabs.

Rahn, J.A.; Nelson, J.H. (Univ. of Nevada, Reno (USA)); O'Donnell, D.J.; Pamer, A.R. (Chemagnetics, Fort Collins, CO (USA))

1989-06-28

86

NMR investigation of Ag nanoparticles  

NASA Astrophysics Data System (ADS)

109Ag nuclear magnetic resonance (NMR) and relaxation measurements have been performed on two powder samples of Ag nanoparticles with average sizes of 20 nm and 80 nm. The measurements have been done in an external field of 9.4 T and in the temperature range 10 K < T < 280 K. The 109Ag NMR spectra for both samples have close to Lorentzian shapes and turn out to be mixtures of homogeneous and inhomogeneous lines. The linewidth ? ? at room temperature is 1.3 kHz for both samples and gradually increases with decreasing temperature. Both the Knight shift ( K) and the nuclear spin-lattice relaxation rate (1/ T 1) are observed to be almost identical to the values reported for the bulk Ag metal, whereby the Korringa ratio R(= K 2 T 1 T/S) is found to be 2.0 for both samples in the investigated temperature range.

Son, Kwanghyo; Jang, Zeehoon

2013-01-01

87

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

88

NMR spectra of transient radicals  

SciTech Connect

A time-resolved method for the study of structure and spin dynamics of transient radicals in liquids is described. Pulsed electron beam or pulsed laser irradiation is used to create transient radicals in solution. Irradiation is carried out in the field of a variable electromagnet, and the diamagnetic products are transferred rapidly using a fast flow system to an NMR probe. During the radical reaction, a 0.5 to 10 ..mu..s rf pulse is applied to the reacting sample at an appropriate frequency, corresponding to a nuclear energy level spacing of the given radical. Nuclear spin level population changes in the radical are transferred to its reaction product and detected as intensity changes in their NMR spectra. The method is illustrated using radiolyzed sodium malonate.

Trifunac, A.D.; Chiu, T.M.; Nuttall, R.H.D.

1984-01-01

89

Two-dimensional NMR spectrometry  

SciTech Connect

This article is the second in a two-part series. In part one (ANALYTICAL CHEMISTRY, May 15) the authors discussed one-dimensional nuclear magnetic resonance (NMR) spectra and some relatively advanced nuclear spin gymnastics experiments that provide a capability for selective sensitivity enhancements. In this article and overview and some applications of two-dimensional NMR experiments are presented. These powerful experiments are important complements to the one-dimensional experiments. As in the more sophisticated one-dimensional experiments, the two-dimensional experiments involve three distinct time periods: a preparation period, t/sub 0/; an evolution period, t/sub 1/; and a detection period, t/sub 2/.

Farrar, T.C.

1987-06-01

90

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

91

Fourier Analysis and Structure Determination. Part II: Pulse NMR and NMR Imaging.  

ERIC Educational Resources Information Center

Uses simple pulse NMR experiments to discuss Fourier transforms. Studies the generation of spin echoes used in the imaging procedure. Shows that pulse NMR experiments give signals that are additions of sinusoids of differing amplitudes, frequencies, and phases. (MVL)

Chesick, John P.

1989-01-01

92

Solution NMR of Large Molecules and Assemblies †  

Microsoft Academic Search

Solution NMR spectroscopy represents a powerful tool for examining the structure and function of biological macromolecules. The advent of multidimensional (2D-4D) NMR, together with the widespread use of uniform isotopic labeling of proteins and RNA with the NMR-active isotopes, 15N and 13C, opened the door to detailed analyses of macromolecular structure, dynamics, and interactions of smaller macromolecules (<25 kDa). Over

Mark P. Foster; Craig A. McElroy; Carlos D. Amero

2007-01-01

93

On-stream NMR measurements and control  

Microsoft Academic Search

Four examples are described in which nuclear magnetic resonance (NMR) measurements provided quantitative analyses with an\\u000a accuracy of 1% of the amount measured. In the first instance, the amplitude of the NMR absorption of hydrogen was combined\\u000a with the weight and volume of the sample to give a moisture determination in starch. The second NMR instrument used no sample\\u000a weight

William L. Rollwitz; Gilbert A. Persyn

1971-01-01

94

Observation of NMR noise from solid samples  

PubMed Central

We demonstrate that proton NMR noise signals, i.e. NMR spectra without excitation by radio frequency, can be obtained from solid samples. Experimental results are shown for static and magic-angle spinning conditions. In addition, a tuning procedure based on the probes’ NMR noise characteristics and similar to the one described previously for liquids probes can also be used to optimize signal-to-noise ratios in 1H-MAS experiments. PMID:20850362

Schlagnitweit, Judith; Dumez, Jean-Nicolas; Nausner, Martin; Jerschow, Alexej; Elena-Herrmann, Benedicte; Muller, Norbert

2010-01-01

95

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

96

Multiple quantum NMR dynamics in pseudopure states  

NASA Astrophysics Data System (ADS)

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

Furman, G. B.

2009-01-01

97

Journal of Biomolecular NMR, 2 (1992) 619-629 619 J-Bio NMR 094  

E-print Network

, one-dimensional; 2D, two-dimensional; 3D, three-dimensional; 4D, four-dimensional; NOESY, nuclearJournal of Biomolecular NMR, 2 (1992) 619-629 619 ESCOM J-Bio NMR 094 Processing of multi dimensional NMR data with the new software PROSA Peter Güntert, Volker Dötsch, Gerhard Wider and Kurt Wüthrich

Wider, Gerhard

98

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

ERIC Educational Resources Information Center

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

Mills, Nancy S.; Shanklin, Michael

2011-01-01

99

NMR spectroscopic studies of "titanocene"  

E-print Network

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... OF FIGURES 111 V1 V1 i INTRODUCTION RESULTS AND DISCUSSION EXPERIMENTAL 32 VITA 37 ix LIST OF TABLES Table Page Infrared Spectra of "Titanocene" II. Metal Hydride Inf rared Absorption Frequencies III. Mass Spectral Data 16 IV. Chemical Shifts...

Birkelbach, Donald Floyd

2012-06-07

100

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

101

Picoliter H-1 NMR Spectroscopy  

SciTech Connect

A RF probe that fits inside the bore of a small gradient coil package is described for routine 1H-NMR microscopy measurements on small samples. The probe operates at 500 MHz and houses a 267-um-diameter solenoid transceiver. When used in three dimensional chemical shift imaging (3D-CSI) experiments, the measured signal-to-noise ratio (SNR) is shown to be within 20-30 percent of theoretical limits formulated by only considering the solenoid's resistive losses. This is illustrated using a 100-um-diameter globule of triacylglycerols ({approx}900mM) that may be an oocyte precursor in young Xenopus Laevis frogs, and water sample containing choline at a concentration often found in live cells ({approx}33mM). In chemical shift images generated using a few thousand scans, the choline methyl line is found to have an acceptable SNR in resolved from just 5 picoliters in the Xenopus globule. It is concluded that the probe's sensitivity is sufficient for performing 1H-NMR on picoliter-scale volumes in biological cells and tissues.

Minard, Kevin R.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Wind, Robert A.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

2002-02-01

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

Using Cloud Storage for NMR Data Distribution  

ERIC Educational Resources Information Center

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

Soulsby, David

2012-01-01

104

NMR quantum computation with indirectly coupled gates  

E-print Network

An NMR realization of a two-qubit quantum gate which processes quantum information indirectly via couplings to a spectator qubit is presented in the context of the Deutsch-Jozsa algorithm. This enables a successful comprehensive NMR implementation of the Deutsch-Jozsa algorithm for functions with three argument bits and demonstrates a technique essential for multi-qubit quantum computation.

David Collins; K. W. Kim; W. C. Holton; H. Sierzputowska-Gracz; E. O. Stejskal

1999-10-01

105

Solving structures by NMR Qinghua Wang  

E-print Network

Fourier transform NMR 1975 Jeener, Ernst 2D NMR 1985 Wüthrich first solution structure of a small protein and their chemical shifts. Spin systems are connected sequentially using short-range NOE correlations from a 2D NOESY spectrum, usually dN and dNN (indicated by ------, below left). 2D COSY NH H H #12;Wider, Biotechniques, 29

Hardy, Jeanne

106

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

107

Sample patterning on NMR surface microcoils  

Microsoft Academic Search

Aligned microcontact printing for patterning the sample in areas of homogeneous RF-field on the highly sensitive surface of planar NMR microprobes is presented. We experimentally demonstrate that sample patterning allows drastic improvement of the spin excitation uniformity. The NMR microprobes are designed for cell analysis and characterized using lipid vesicles as cell substitutes. Lipid vesicles are advantageous as composition and

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

2006-01-01

108

Solenoidal and planar microcoils for NMR spectroscopy  

Microsoft Academic Search

The extraction of nuclear magnetic resonance (NMR) spectra of samples having smaller and smaller volumes is a real challenge. Reductions of volume are dictated by the difficulties of production of sufficiently large samples or by necessities of miniaturization of the analyzing system. In both cases a careful design of the radiofrequency (RF) coil, ensuring an optimum reception of the NMR

M. Armenean; O. Beuf; L. Renaud; H. Saint-Jalmes

2003-01-01

109

Supporting Information High-Yielding Staudinger Ligation of a Phosphinothioester and Azide  

E-print Network

and Varian UNITY-500 spectrometers. Phosphorus-31 NMR spectra were proton-decoupled and referenced against!). The resulting black oil was dissolved in methylene chloride (0.35 L), and this solution was washed with 2 N HCl

Raines, Ronald T.

110

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

111

An Introduction to Biological NMR Spectroscopy*  

PubMed Central

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

Marion, Dominique

2013-01-01

112

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

113

Solid-state NMR crystallography through paramagnetic restraints.  

PubMed

Pseudocontact shifts (PCSs) measured by solid-state NMR spectroscopy (SS-NMR) on microcrystalline powders of a paramagnetic metalloprotein permit NMR crystallography. Along with other restraints for SS-NMR experiments, the protein molecular structure as well as the correct crystal packing are obtained. PMID:22393876

Luchinat, Claudio; Parigi, Giacomo; Ravera, Enrico; Rinaldelli, Mauro

2012-03-21

114

Fast approximate Duplicate Detection for 2D-NMR Spectra  

E-print Network

Fast approximate Duplicate Detection for 2D-NMR Spectra Bj¨orn Egert1 , Steffen Neumann1. In contrast to 1D-NMR spectra, 2D-NMR spectra correlate the chemical shifts of 1 H and 13 C simultaneously a definition of duplicates with the desired robustness properties mandatory for 2D-NMR experiments. A major

Hinneburg, Alexander

115

STRUCTUREu DITERPENE ELUCIDATION FROM 1 3 C NMR  

E-print Network

products (not proteins), only 1 H NMR and 1 3 C NMR spectroscopy, including combined methods such as 2D NMRSTRUCTUREu DITERPENE ELUCIDATION FROM 1 3 C NMR SPECTRA WITH INDUCTIVE LOGIC PROGRAMMING SASÏ O DZÏ Programming (ILP) to the problem of diterpene structure elucidation from 1 3 C NMR spectra. Diterpenes

Dzeroski, Saso

116

Multidimensional NMR Spectroscopy DOI: 10.1002/anie.200805612  

E-print Network

Multidimensional NMR Spectroscopy DOI: 10.1002/anie.200805612 Single-Scan 2D Hadamard NMR resonance (2D NMR) experiments has been a topic of intense research during the past years.[1] Proposals as compressing the 2D NMR experiment into a single-scan by spatially encoding the indirect-domain interactions.[3

Frydman, Lucio

117

A review of Blind Source Separation in NMR Spectroscopy  

E-print Network

M to �M for classical NMR ). Remarkably, the resolution of 2D NMR spectra is such that even by visA review of Blind Source Separation in NMR Spectroscopy Ichrak Toumi, Stefano Caldarelli iSm2, UMR naturally associated to most NMR experi- ments. Notable exceptions are Pulse Field Gradient and relaxation

118

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

119

Solvent signal as an NMR concentration reference.  

PubMed

We propose that the NMR solvent signal be utilized as a universal concentration reference because most solvents can be observed by NMR and solvent concentrations can be readily calculated or determined independently. In particular, a highly protonated solvent such as water can serve as a primary concentration standard for its stability, availability, and ease of observation. The potential problems of radiation damping associated with a strong NMR signal can be alleviated by small pulse angle excitation. The solvent signal then can be detected by the NMR receiver with the same efficiency as a dilute analyte. We demonstrated that the analyte's proton concentration can be accurately determined from 4 microM to more than 100 M, referenced by solvent (water) protons of concentrations more than 10 M. The proposed method is robust and indifferent to probe tuning and does not require any additional concentration standard. PMID:19007190

Mo, Huaping; Raftery, Daniel

2008-12-15

120

Quantitative analysis of NMR spectra with chemometrics  

NASA Astrophysics Data System (ADS)

The number of applications of chemometrics to series of NMR spectra is rapidly increasing due to an emerging interest for quantitative NMR spectroscopy e.g. in the pharmaceutical and food industries. This paper gives an analysis of advantages and limitations of applying the two most common chemometric procedures, Principal Component Analysis (PCA) and Multivariate Curve Resolution (MCR), to a designed set of 231 simple alcohol mixture (propanol, butanol and pentanol) 1H 400 MHz spectra. The study clearly demonstrates that the major advantage of chemometrics is the visualisation of larger data structures which adds a new exploratory dimension to NMR research. While robustness and powerful data visualisation and exploration are the main qualities of the PCA method, the study demonstrates that the bilinear MCR method is an even more powerful method for resolving pure component NMR spectra from mixtures when certain conditions are met.

Winning, H.; Larsen, F. H.; Bro, R.; Engelsen, S. B.

2008-01-01

121

Ab initio converse NMR approach for pseudopotentials  

E-print Network

We extend the recently developed converse NMR approach [Thonhauser et al., J. Chem. Phys. 131, 101101 (2009)] such that it can be used in conjunction with norm-conserving, nonlocal pseudopotentials. This extension permits ...

Ceresoli, Davide

122

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

123

Planar microcoil-based microfluidic NMR probes  

Microsoft Academic Search

Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300MHz with three different probes having observed sample volumes of respectively 30, 120, and 470nL. The achieved sensitivity enables acquisition of an 1H spectrum of 160?g sucrose in D2O, corresponding to a

C. Massin; F. Vincent; A. Homsy; K. Ehrmann; G. Boero; P.-A Besse; A. Daridon; E. Verpoorte; N. F de Rooij; R. S Popovic

2003-01-01

124

NMR profiling of transgenic peas.  

PubMed

A high throughput proton nuclear magnetic resonance spectroscopy method for the metabolite fingerprinting of plants was applied to genetically modified peas (Pisum sativum) to determine whether biochemical changes, so called 'unintended effects', beyond those intended by incorporation of a transgene, were detectable. Multivariate analysis of 1H NMR (nuclear magnetic resonance) spectra obtained from uniformly grown glasshouse plants revealed differences between the transgenic and control group that exceeded the natural variation of the plants. When a larger data set of six related transgenic lines was analysed, including a null segregant in addition to the wild-type control, multivariate analysis showed that the distribution of metabolites in the transgenics was different from that of the null segregant. However, the profile obtained from the wild-type material was diverse in comparison with both the transgenics and the null segregant, suggesting that the primary cause of the observed differences was that the transformation process selects for a subset of individuals able to undergo the transformation and selection procedures, and that their descendants have a restricted variation in metabolite profile, rather than that the presence of the transgene itself generates these differences. PMID:17166140

Charlton, Adrian; Allnutt, Theo; Holmes, Stephen; Chisholm, James; Bean, Samantha; Ellis, Noel; Mullineaux, Phil; Oehlschlager, Sarah

2004-01-01

125

Moderne Entwicklung der NMR (Nuclear Magnetic Resonance)  

NASA Astrophysics Data System (ADS)

Die NMR-Spektroskopie kann sich altersmäßig nicht mit den Annalen der Physik messen; sie entstand vor rd. 45 Jahren. Ihre Entwicklung wurde und wird durch unterschiedliche Erfahrungen, Erkenntnisse und Techniken bestimmt; sie zeigt, daß auch heute noch die Fortschritte von Spezialgebieten Impulse aus weiten Bereichen der Physik, der Naturwissenschaften und Technik beziehen. In entsprechender Weise machen Spezialzeitschriften das Erscheinen allgemeiner Fachzeitschriften nicht überflüssig. Diese Zusammenhänge sollen an einigen Beispielen der NMR demonstriert werden.Translated AbstractModern Development of NMR (Nuclear Magnetic Resonance)The age of NMR-spectroscopy is not comparable with that of the Annalen der Physik; NMR was established only about 45 years ago. Its development was promoted by different experience, knowledge and techniques; it shows that also in these days the progress of a special topic depends on stimulations by other parts of physics, of natural and technical science. In an analogous way general scientific journals are not made superfluous by the existence of special papers. These relations are demonstrated with some examples in NMR.

Lösche, Artur

126

Sparse Sampling Methods In Multidimensional NMR  

PubMed Central

Although the discrete Fourier transform played an enabling role in the development of modern NMR spectroscopy, it suffers from a well-known difficulty providing high-resolution spectra from short data records. In multidimensional NMR experiments, so-called indirect time dimensions are sampled parametrically, with each instance of evolution times along the indirect dimensions sampled via separate one-dimensional experiments. The time required to conduct multidimensional experiments is directly proportional to the number of indirect evolution times sampled. Despite remarkable advances in resolution with increasing magnetic field strength, multiple dimensions remain essential for resolving individual resonances in NMR spectra of biological macromolecues. Conventional Fourier-based methods of spectrum analysis limit the resolution that can be practically achieved in the indirect dimensions. Nonuniform or sparse data collection strategies, together with suitable non-Fourier methods of spectrum analysis, enable high-resolution multidimensional spectra to be obtained. Although some of these approaches were first employed in NMR more than two decades ago, it is only relatively recently that they have been widely adopted. Here we describe the current practice of sparse sampling methods and prospects for further development of the approach to improve resolution and sensitivity and shorten experiment time in multidimensional NMR. While sparse sampling is particularly promising for multidimensional NMR, the basic principles could apply to other forms of multidimensional spectroscopy. PMID:22481242

Mobli, Mehdi; Maciejewski, Mark W.; Schuyler, Adam D.; Stern, Alan S.; Hoch, Jeffrey C.

2014-01-01

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

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

129

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

130

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

131

SedNMR: on the edge between solution and solid-state NMR.  

PubMed

Solid-state NMR (SS-NMR) of proteins requires that those molecules be immobilized, usually by crystallization, freezing, or lyophilization. However, self-crowding can also slow molecular rotation sufficiently to prevent the nuclear interactions from averaging. To achieve self-crowding, researchers can use a centrifugal field to create a concentration gradient or use regular ultracentrifugation to produce highly concentrated, gel-like solutions. Thus sedimented solute NMR (SedNMR) provides a simple method to prepare biological samples for SS-NMR experiments with minimal perturbation. This method may also give researchers a way to investigate species that are not otherwise accessible by NMR. We induce the sedimentation in one of two ways: (1) by the extreme centrifugal force exerted during magic angle spinning (MAS-induced sedimentation or in situ) or (2) by an ultracentrifuge (UC-induced sedimentation or ex situ). Sedimentation is particularly useful in situations where it is difficult to obtain protein crystals. Furthermore, because the proteins remain in a largely hydrated state, the sedimented samples may provide SS-NMR spectra that have better resolution than the spectra from frozen solutions or lyophilized powders. If sedimentation is induced in situ, the same protein sample can be used for both solution and SS-NMR studies. Finally, we show that in situ SedNMR can be used to detect the NMR signals of large molecular adducts that have binding constants that are too weak to allow for the selective isolation and crystallization of the complexed species. We can selectively induce sedimentation for the heaviest molecular species. Because the complexed molecules are subtracted from the bulk solution, the reaction proceeds further toward the formation of complexes. PMID:23470055

Bertini, Ivano; Luchinat, Claudio; Parigi, Giacomo; Ravera, Enrico

2013-09-17

132

BOOK REVIEW: NMR Imaging of Materials  

NASA Astrophysics Data System (ADS)

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

Blümich, Bernhard

2003-09-01

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

Radiation damping in microcoil NMR probes  

NASA Astrophysics Data System (ADS)

Radiation damping arises from the field induced in the receiver coil by large bulk magnetization and tends to selectively drive this magnetization back to equilibrium much faster than relaxation processes. The demand for increased sensitivity in mass-limited samples has led to the development of microcoil NMR probes that are capable of obtaining high quality NMR spectra with small sample volumes (nL-?L). Microcoil probes are optimized to increase sensitivity by increasing either the sample-to-coil ratio (filling factor) of the probe or quality factor of the detection coil. Though radiation damping effects have been studied in standard NMR probes, these effects have not been measured in the microcoil probes. Here a systematic evaluation of radiation damping effects in a microcoil NMR probe is presented and the results are compared with similar measurements in conventional large volume samples. These results show that radiation-damping effects in microcoil probe is much more pronounced than in 5 mm probes, and that it is critically important to optimize NMR experiments to minimize these effects. As microcoil probes provide better control of the bulk magnetization, with good RF and B0 inhomogeneity, in addition to negligible dipolar field effects due to nearly spherical sample volumes, these probes can be used exclusively to study the complex behavior of radiation damping.

Krishnan, V. V.

2006-04-01

135

Solid-state NMR of proteins sedimented by ultracentrifugation  

PubMed Central

Relatively large proteins in solution, spun in NMR rotors for solid samples at typical ultracentrifugation speeds, sediment at the rotor wall. The sedimented proteins provide high-quality solid-state-like NMR spectra suitable for structural investigation. The proteins fully revert to the native solution state when spinning is stopped, allowing one to study them in both conditions. Transiently sedimented proteins can be considered a novel phase as far as NMR is concerned. NMR of transiently sedimented molecules under fast magic angle spinning has the advantage of overcoming protein size limitations of solution NMR without the need of sample crystallization/precipitation required by solid-state NMR. PMID:21670262

Bertini, Ivano; Luchinat, Claudio; Parigi, Giacomo; Ravera, Enrico; Reif, Bernd; Turano, Paola

2011-01-01

136

Solid-state NMR of proteins sedimented by ultracentrifugation.  

PubMed

Relatively large proteins in solution, spun in NMR rotors for solid samples at typical ultracentrifugation speeds, sediment at the rotor wall. The sedimented proteins provide high-quality solid-state-like NMR spectra suitable for structural investigation. The proteins fully revert to the native solution state when spinning is stopped, allowing one to study them in both conditions. Transiently sedimented proteins can be considered a novel phase as far as NMR is concerned. NMR of transiently sedimented molecules under fast magic angle spinning has the advantage of overcoming protein size limitations of solution NMR without the need of sample crystallization/precipitation required by solid-state NMR. PMID:21670262

Bertini, Ivano; Luchinat, Claudio; Parigi, Giacomo; Ravera, Enrico; Reif, Bernd; Turano, Paola

2011-06-28

137

SEAL by NMR: Glyco-Based Selenium-Labeled Affinity Ligands Detected by NMR Spectroscopy.  

PubMed

We report a method for the screening of interactions between proteins and selenium-labeled carbohydrate ligands. SEAL by NMR is demonstrated with selenoglycosides binding to lectins where the selenium nucleus serves as an NMR-active handle and reports on binding through (77) Se NMR spectroscopy. In terms of overall sensitivity, this nucleus is comparable to (13) C?NMR, while the NMR spectral width is ten times larger, yielding little overlap in (77) Se NMR spectroscopy, even for similar compounds. The studied ligands are singly selenated bioisosteres of methyl glycosides for which straightforward preparation methods are at hand and libraries can readily be generated. The strength of the approach lies in its simplicity, sensitivity to binding events, the tolerance to additives and the possibility of having several ligands in the assay. This study extends the increasing potential of selenium in structure biology and medicinal chemistry. We anticipate that SEAL by NMR will be a beneficial tool for the development of selenium-based bioactive compounds, such as glycomimetic drug candidates. PMID:25196366

Hamark, Christoffer; Landström, Jens; Widmalm, Göran

2014-10-20

138

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

139

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

140

NMR spectra of androstane analogs of brassinosteroids  

NASA Astrophysics Data System (ADS)

We have used two-dimensional NMR spectroscopy to make a complete assignment of signals from the nuclei of hydrogen and carbon atoms in the spectra of brassinosteroids in the androstane series. We have confirmed the stereochemistry of the chiral centers and the structure of the molecules. We have studied the effect of the configuration of the 2,3-diol groups in the A ring of the steroids on the chemical shift of adjacent atoms in the 13C and 1H NMR spectra.

Baranovskii, A. V.; Litvinovskaya, R. P.; Aver'kova, M. A.; Khripach, N. B.; Khripach, V. A.

2007-09-01

141

Copper trafficking in biology: an NMR approach  

PubMed Central

Copper ions are essential for living organisms because they are involved in several fundamental biological processes. Biomolecules interacting with copper ions have to be characterized as such, when bound to the metal ion, and when they interact with other biomolecules or substrates. The characterization is both structural and dynamic. In this context, NMR is a preferred tool of investigation because it allows shedding light on what happens in solution. Here, the NMR contribution to the copper trafficking is described, providing precious information on biochemical pathways, which are essential to understand the mechanisms of life at the molecular level. PMID:19949444

Banci, Lucia; Bertini, Ivano; Ciofi-Baffoni, Simone

2009-01-01

142

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; Sonnichsen, Frank D.; Sanders, Charles R.

2013-01-01

143

NMR studies of aureobasidins A and E.  

PubMed

The 1H and 13C NMR spectra of aureobasidins A and E were analyzed by a variety of 2D NMR techniques. Two isomers of aureobasidin A existed as an equilibrium mixture in deuteriochloroform. The isomerism was associated with cis-trans rotation of the amide bond between N-methylphenylalanine and proline. Almost all of the aureobasidin E was found in deuteriochloroform as one conformer; the amide bond between beta-hydroxy-N-methylphenylalanine and proline was in the cis-conformation. Experiments with the NOE made identification of the conformation of the amide bonds of aureobasidins A and E possible. PMID:1761416

Ikai, K; Shiomi, K; Takesako, K; Kato, I; Naganawa, H

1991-11-01

144

Applications of noble gas NMR to condensed matter systems  

Microsoft Academic Search

The spin-off of laser-polarized noble gases (^3He and ^129Xe) from atomic physics to biomedical imaging has renewed interest in gas-phase NMR and MRI. We are applying noble gas NMR to studies of condensed matter systems such as porous media and liquid xenon. NMR measurements of restricted noble gas diffusion in porous media offer two important advantages over conventional (liquid) NMR

C.-H. Tseng; R. W. Mair; G. P. Wong; R. L. Walsworth; S. Patz; D. Williamson; M. D. Hurlimann; L. M. Schwartz; D. G. Cory

1998-01-01

145

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

146

Optimal control in NMR spectroscopy: Numerical implementation in SIMPSON  

Microsoft Academic Search

We present the implementation of optimal control into the open source simulation package SIMPSON for development and optimization of nuclear magnetic resonance experiments for a wide range of applications, including liquid- and solid-state NMR, magnetic resonance imaging, quantum computation, and combinations between NMR and other spectroscopies. Optimal control enables efficient optimization of NMR experiments in terms of amplitudes, phases, offsets

Zden?k Tošner; Thomas Vosegaard; Cindie Kehlet; Navin Khaneja; Steffen J. Glaser; Niels Chr. Nielsen

2009-01-01

147

Chemical shift referencing in MAS solid state NMR  

Microsoft Academic Search

Solid state 13C magic angle spinning (MAS) NMR spectra are typically referenced externally using a probe which does not incorporate a field frequency lock. Solution NMR shifts on the other hand are more often determined with respect to an internal reference and using a deuterium based field frequency lock. Further differences arise in solution NMR of proteins and nucleic acids

Corey R Morcombe; Kurt W Zilm

2003-01-01

148

CISA: Combined NMR Resonance Connectivity Information Determination and  

E-print Network

bonds in the target protein. For example, an HSQC peak list contains 2D peaks, each of which is a pairCISA: Combined NMR Resonance Connectivity Information Determination and Sequential Assignment Xiang to successful protein structure determination via NMR spectroscopy. Assuming the availability of a set of NMR

Lin, Guohui

149

Communication Interlaced Fourier transformation of ultrafast 2D NMR data  

E-print Network

Communication Interlaced Fourier transformation of ultrafast 2D NMR data Mor Mishkovsky, Lucio in ultrafast 2D NMR is discussed and exemplified, based on the interlaced Fourier transformation. This approach- and heteronuclear ultrafast 2D NMR acquisitions, and found systematically fulfilled. The robustness and conditions

Frydman, Lucio

150

Ultrafast two-dimensional NMR spectroscopy using constant acquisition gradients  

E-print Network

and on continuously flowing samples, as well as the utilization of 2D NMR to follow dynamic biophysical and metabolicUltrafast two-dimensional NMR spectroscopy using constant acquisition gradients Yoav Shrot NMR spectroscopy plays an important role in the characterization of molecular structure and dynamics

Frydman, Lucio

151

The acquisition of multidimensional NMR spectra within a single scan  

E-print Network

such as proteins folding, 2D NMR experiments on samples being chromatographed, bring the duration of higher hardware; its performance is ex- emplified here with a variety of homonuclear 2D NMR acquisitions. Few is not just to measure but to correlate NMR frequencies over several spectral dimensions. For instance in 2D

Frydman, Lucio

152

Spatially resolved multidimensional NMR spectroscopy within a single scan  

E-print Network

-dimensional (2D) NMR experiments can in fact provide a weighted spatial distribution of the analyte originating where the potential of spatially resolved ultrafast 2D NMR spectroscopy is brought to bear are presented. All rights reserved. Keywords: Magnetic resonance spectroscopy; 2D 1 H NMR; Spatial localization

Frydman, Lucio

153

Communication Arrayed acquisition of 2D exchange NMR spectra within  

E-print Network

Communication Arrayed acquisition of 2D exchange NMR spectra within a single scan experiment Boaz time. Further, since 2D exchange NMR spectra can nowadays be themselves collected within one scan evolution, particularly with the advent of 2D NMR spectroscopy [11,12]. Signals Sðt1; t2�

Frydman, Lucio

154

Communication Single-scan 2D DOSY NMR spectroscopy  

E-print Network

Communication Single-scan 2D DOSY NMR spectroscopy Yoav Shrot, Lucio Frydman * Department. Introduction Two-dimensional nuclear magnetic resonance (2D NMR) plays a fundamental role in expanding on the principles and applications of the resulting 2D diffusion-shift NMR correlation experiment, have been given

Frydman, Lucio

155

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.

156

Microspectrometer for NMR: analysis of small quantities in vitro  

Microsoft Academic Search

This paper reports the design, fabrication and preliminary tests of planar microcoils associated with a micromachined channel in silicon. These microcoils are used as nuclear magnetic resonance (NMR) radio frequency detection coils. They allow in vitro NMR analysis of small quantities introduced into the microchannel. It is a real challenging task to develop microsystems for NMR spectrum extraction for smaller

B. Sorli; J. F. Chateaux; M. Pitaval; H. Chahboune; B. Favre; A. Briguet; P. Morin

2004-01-01

157

QCCM - Center for NMR Quantum Information Processing.  

National Technical Information Service (NTIS)

Over the course of the project we have completed the liquid state NMR implementation of the QIP test-bed and are now using it to explore a variety of efficient error finding protocols. This setup has enabled us to extend the coherent control methods to su...

C. Ramanathan, D. G. Cory, J. Baugh, J. V. Emerson, R. Laflamme

2011-01-01

158

A Primer of Fourier Transform NMR.  

ERIC Educational Resources Information Center

Fourier transform nuclear magnetic resonance (NMR) is a new spectroscopic technique that is often omitted from undergraduate curricula because of lack of instructional materials. Therefore, information is provided to introduce students to the technique of data collection and transformation into the frequency domain. (JN)

Macomber, Roger S.

1985-01-01

159

Ensemble quantum computing by NMR spectroscopy  

PubMed Central

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

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

1997-01-01

160

Algorithmic cooling and scalable NMR quantum computers  

E-print Network

Algorithmic cooling and scalable NMR quantum computers P. Oscar Boykin*, Tal Mor§ , Vwani, Israel; Computer Science Department, Technion, Technion City, Haifa 32000, Israel; ¶Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109; and RAS Computer

Mor, Tal

161

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

162

NMR analysis of a fluorocarbon copolymer  

SciTech Connect

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

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

1987-10-01

163

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

164

Electric field N.M.R  

Microsoft Academic Search

Application of a strong de electric field to solutions of apolar molecules in an apolar solvent leads to partial orientation of the molecules. This orientation could be detected by N.M.R. spectroscopy through the anisotropic spin interactions that show up in the spectra. Subsequent analysis of the spectrum leads to information about the static electric polarizability tensor (a). The electric field

B. H. Ruessink; C. Maclean

1987-01-01

165

NMR Measurements of Granular Flow and Compaction  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) can be used to measure statistical distributions of granular flow velocity and fluctuations of velocity, as well as spatial distributions of particulate concentration, flow velocity, its fluctuations, and other parameters that may be derived from these. All measurements have been of protons in liquid-containing particles such as mustard seeds or pharmaceutical pills. Our favorite geometry has

Eiichi Fukushima

1998-01-01

166

Planar microcoil-based microfluidic NMR probes  

NASA Astrophysics Data System (ADS)

Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120, and 470 nL. The achieved sensitivity enables acquisition of an 1H spectrum of 160 ?g sucrose in D 2O, corresponding to a proof-of-concept for on-chip NMR spectroscopy. Increase of mass-sensitivity with coil diameter reduction is demonstrated experimentally for planar microcoils. Models that enable quantitative prediction of the signal-to-noise ratio and of the influence of microfluidic channel geometry on spectral resolution are presented and successfully compared to the experimental data. The main factor presently limiting sensitivity for high-resolution applications is identified as being probe-induced static magnetic field distortions. Finally, based on the presented model and measured data, future performance of planar microcoil-based microfluidic NMR probes is extrapolated and discussed.

Massin, C.; Vincent, F.; Homsy, A.; Ehrmann, K.; Boero, G.; Besse, P.-A.; Daridon, A.; Verpoorte, E.; de Rooij, N. F.; Popovic, R. S.

2003-10-01

167

Implantable planar rf microcoils for NMR microspectroscopy  

Microsoft Academic Search

This communication reports the design, the fabrication and preliminary tests of planar microcoils used as nuclear magnetic resonance (NMR) radio frequency (rf) detection coils. The magnetic coupling between a rf coil and a sample is maximized by physically designing the coil as small as possible as to just accommodate the sample. Maximum coupling corresponds directly to an optimal sensitivity for

L. Renaud; M. Armenean; L. Berry; P. Kleimann; P. Morin; M. Pitaval; J. O’Brien; M. Brunet; H. Saint-Jalmes

2002-01-01

168

An integrated CMOS microsystem for NMR applications  

Microsoft Academic Search

A monolithic CMOS microsystem for nuclear magnetic resonance applications has been designed and tested. It includes two planar microcoils and a complete readout electronics with a single 3.3 V supply. It measures static fields around 1 T with a field resolution better than 1 ppm\\/?Hz. The probe can also be used for NMR spectroscopy with a spectral resolution of 15

J. Frounchi; G. Boero; B. Furrer; P.-A. Besse; R. S. Popovic

2001-01-01

169

Monolithic gallium arsenide receiver for NMR microscopy  

Microsoft Academic Search

The goal of this research is to improve the performance of NMR microscopy systems by fabricating the RF detection microcoil and preamplifier on a single monolithic GaAs substrate. The planar microcoil consists of 4-7 turns of gold conductor. A simple impedance matching network links the microcoil to a single stage, common source configuration, GaAs MESFET preamplifier

T. L. Peck; S. J. Franke; M. Feng; J. Kruse; R. L. Magin

1994-01-01

170

Planar microcoil-based microfluidic NMR probes.  

PubMed

Microfabricated small-volume NMR probes consisting of electroplated planar microcoils integrated on a glass substrate with etched microfluidic channels are fabricated and tested. 1H NMR spectra are acquired at 300 MHz with three different probes having observed sample volumes of respectively 30, 120, and 470 nL. The achieved sensitivity enables acquisition of an 1H spectrum of 160 microg sucrose in D2O, corresponding to a proof-of-concept for on-chip NMR spectroscopy. Increase of mass-sensitivity with coil diameter reduction is demonstrated experimentally for planar microcoils. Models that enable quantitative prediction of the signal-to-noise ratio and of the influence of microfluidic channel geometry on spectral resolution are presented and successfully compared to the experimental data. The main factor presently limiting sensitivity for high-resolution applications is identified as being probe-induced static magnetic field distortions. Finally, based on the presented model and measured data, future performance of planar microcoil-based microfluidic NMR probes is extrapolated and discussed. PMID:14511593

Massin, C; Vincent, F; Homsy, A; Ehrmann, K; Boero, G; Besse, P-A; Daridon, A; Verpoorte, E; de Rooij, N F; Popovic, R S

2003-10-01

171

NMR implantable probe: limit of metabolites detection  

Microsoft Academic Search

In this study a new concept of micro coil is presented in order to measure the small volumes and small concentrations samples by NMR spectroscopy. The goal of our work is to determine the concentration sensitivity and the limit of detection of a planar microcoil of ellipsoidal geometry 1000 x 500 ?m, fabricated using an electro plating technique and used

N. Baxan; J. F. Châteaux; A. Rengle; H. Rabeson; A. Briguet; G. Pasquet; P. Morin

172

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

173

Solid-State NMR for Bacterial Biofilms  

PubMed Central

Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state NMR is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an E. coli biofilm and transform our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area. PMID:24976646

Reichhardt, Courtney; Cegelski, Lynette

2014-01-01

174

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

175

Simultaneous multinuclear NMR studies of brain metabolism  

SciTech Connect

The brain is a complex metabolic system with intricate interactions between the various metabolic pathways to provide the tight regulation necessary to maintain homeostasis. A major problem faced by investigators studying metabolic regulation in vivo, is the inability to noninvasively follow the evolution of changes in metabolite concentrations during imposed metabolic stress. The work described in this thesis develops in vivo NMR spectroscopy into a technique to simultaneously monitor levels of high energy phosphate metabolites, intracellular pH, lactate concentrations and ionic equilibria in a time resolved fashion, and applies this technique to study metabolic regulation in the brain. The basic technique involves frequency interleaved NMR data acquisition, allowing spectra from several nuclei to be acquired in the same time it would take to acquire a spectrum from a single nucleus. In order to permit such frequency time shared use of the NMR spectrometer, it is necessary to develop multiple tuned NMR probes, capable of operating at several different frequencies with high sensitivity. Probes using multiple-pole tuning networks and coupled tank circuits individually or in combination are described. Applications of double (/sup 31/P, /sup 1/H) and triple /sup 23/Na, /sup 1/H, /sup 31/P) nuclear NMR to study metabolic regulation in cat brain models of hypoxic ischemia and global seizure are described. The results are consistent with regulation of oxidative metabolism in the brain in vivo by the phosphorylation ratio, a potent regulator of in vitro mitochondrial function. Measurements of the brain buffering capacity and post isochemic lactate efflux are presented. A close correlation between the transmembrane Na/sup +/ gradient and the energy state is established.

Schnall, M.D.

1986-01-01

176

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

E-print Network

on the 13 C linewidths of U-13 C, 15 N 2D crystalline bacteriorhodopsin (bR) from Halobacterium salinariumNMR 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

177

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

178

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

179

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

180

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

181

Sodium ion effect on silk fibroin conformation characterized by solid-state NMR and generalized 2D NMR NMR correlation  

NASA Astrophysics Data System (ADS)

In the present work, we investigated Na + ion effect on the silk fibroin (SF) conformation. Samples are Na +-involved regenerated silk fibroin films. 13C CP-MAS NMR demonstrates that as added [Na +] increases, partial silk fibroin conformation transit from helix-form to ?-form at certain Na + ion concentration which is much higher than that in Bombyx mori silkworm gland. The generalized two-dimensional NMR-NMR correlation analysis reveals that silk fibroin undergoes several intermediate states during its conformation transition process as [Na +] increase. The appearance order of the intermediates is followed as: helix and/or random coil ? helix-like ? ?-sheet-like ? ?-sheet, which is the same as that produced by pH decrease from 6.8 to 4.8 in the resultant regenerated silk fibroin films. The binding sites of Na + to silk fibroin might involve the carbonyl oxygen atom of certain amino acids sequence which could promote the formation of ?-sheet conformation. Since the Na +sbnd O bond is weak, the ability of Na + inducing the secondary structure transition is weaker than those of Ca 2+, Cu 2+ and even K +. It is maybe a reason why the sodium content is much lower than potassium in the silkworm gland.

Ruan, Qing-Xia; Zhou, Ping

2008-07-01

182

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

183

Contrast agents and spectroscopic probes in NMR  

SciTech Connect

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 T/sub 1/ of H/sub 2/O, 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 attempts as isotopic enrichment (usually C-13), which causes a direct increase in signal.

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

1984-04-01

184

{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

185

(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 times 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.

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

1999-04-23

186

Electric field N.M.R.  

NASA Astrophysics Data System (ADS)

Application of a strong de electric field to solutions of apolar molecules in an apolar solvent leads to partial orientation of the molecules. This orientation could be detected by N.M.R. spectroscopy through the anisotropic spin interactions that show up in the spectra. Subsequent analysis of the spectrum leads to information about the static electric polarizability tensor (a). The electric field N.M.R. (EFNMR) method was applied to measure, from the 2H EFNMR spectrum of naphthalene-d8, the anisotropy of a (i.e. ??), and asymmetry (??). The result is: 7·1 ± 0·3 and -(4·4 ± 0·5) × 10-24 cm3 for ?? and ?? respectively. For triphenylene-d12 the value of ?? is measured to be -(14·4 ± 1·4) × 10-24 cm3. The results from the EFNMR method and from other methods are compared and discussed

Ruessink, B. H.; Maclean, C.

187

Generalized biaxial shearing of MQMAS NMR spectra  

NASA Astrophysics Data System (ADS)

Two dimensional multiple quantum (MQ) MAS NMR experiments have become popular due to the wide applicability of this technique to structural questions in materials science, the abundance of half-integer spin nuclei in the periodic table, and the ease of implementation on typical solid state NMR instruments. In spite of the high-resolution theoretically possible from such experiments, the homogeneous and inhomogeneous broadening factors inherent in many samples of interest can make spectral analysis challenging. We present several possible spectral shearing schemes that may be useful for spectral analysis, and in particular we introduce shearing in the directly detected dimension. We suggest that for amorphous or disordered samples that give broad spectral features, shearing may be used as a general tool for optimal positioning of these features relative to one another and for the characterization of isotropic chemical and quadrupolar shifts.

Gehman, John D.; Provis, John L.

2009-09-01

188

NMR analog of the quantum disentanglement eraser.  

PubMed

We report the implementation of a three-spin quantum disentanglement eraser on a liquid-state NMR quantum information processor. A key feature of this experiment was its use of pulsed magnetic field gradients to mimic projective measurements. This ability is an important step towards the development of an experimentally controllable system which can simulate any quantum dynamics, both coherent and decoherent. PMID:11415376

Teklemariam, G; Fortunato, E M; Pravia, M A; Havel, T F; Cory, D G

2001-06-25

189

NMR experiments of oleuropein biomimetic hydrolysis.  

PubMed

The oleuropein hydrolytic conversion, under biomimetic conditions, induced by the endogenous enzymatic system of the olive fruit, has been monitored by the intermediate derivative formation through (1)H and (13)C NMR spectra; the assigned molecular structures reveal the identity of new bioactive biophenolic metabolites, the hemiacetal aglycon, and the two epimeric dialdehydes, which influence the pathogen antagonism of olive fruits and the hedonistic-sensorial characteristics of olive oil. PMID:10552701

Bianco, A D; Piperno, A; Romeo, G; Uccella, N

1999-09-01

190

Dynamic NMR microscopy of chromatographic columns  

Microsoft Academic Search

Pulsed magnetic field gradients encoded a discrete spatial and temporal motion of the molecules of a fluid percolating through the packed bed of a dynamic radial compression column for liquid chromatography. Two packing materials of porous, chemically bonded C18 silica were used; large irregularly shaped particles (55--105 μm) and small spherical particles (6 μm). By combining pulsed field gradient NMR

Ulrich Tallarek; Ernst Bayer; Dagmar Van Dusschoten; T. W. J. Scheenen; Henk Van As; Georges Guiochon; Uwe D. Neue

1998-01-01

191

NMR study of strongly correlated electron systems  

Microsoft Academic Search

Various types of ground states in strongly correlated electron systems have been systematically investigated by means of NMR\\/NQR at low temperatures under high magnetic field and pressure. We focus on two well-known heavy-electron families, CeCu2X2 (X = Si and Ge) (Ce(122)) and UM2Al3 (M = Ni and Pd) (U(123)). The Cu NQR experiments on CeCu2X2 under high pressure indicate that

Y. Kitaoka; H. Tou; G.-q. Zheng; K. Ishida; K. Asayama; T. C. Kobayashi; A. Kohda; N. Takeshita; K. Amaya; Y. Onuki; G. Geibel; C. Schank; F. Steglich

1995-01-01

192

NMR measurements in solutions of dialkylimidazolium haloaluminates  

Microsoft Academic Search

²⁷Al and ³⁵Cl NMR spectra of AlClâ-1-ethyl-3-methyl imidazolium chloride (EMIC) melts were measured for initial compositions ranging from 50 to 67 mol % AlClâ at various temperatures. It was shown by changing the preaquisition delay time (DE value) that the dominant aluminum species are AlClâ⁻ in the melt formed by mixing 50 mol % with EMIC and AlâClâ⁻ in the

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

1992-01-01

193

Quantitative calibration of radiofrequency NMR Stark effects.  

PubMed

Nuclear magnetic resonance (NMR) Stark responses can occur in quadrupolar nuclei for an electric field oscillating at twice the usual NMR frequency (2?(0)). Calibration of responses to an applied E field is needed to establish nuclear spins as probes of native E fields within material and molecular systems. We present an improved approach and apparatus for accurate measurement of quadrupolar Stark effects. Updated values of C(14) (the response parameter in cubic crystals) were obtained for both (69)Ga and (75)As in GaAs. Keys to improvement include a modified implementation of voltage dividers to assess the 2?(0) amplitude, |E|, and the stabilization of divider response by reduction of stray couplings in 2?(0) circuitry. Finally, accuracy was enhanced by filtering sets of |E| through a linear response function that we established for the radiofrequency amplifier. Our approach is verified by two types of spectral results. Steady-state 2?(0) excitation to presaturate NMR spectra yielded C(14) = (2.59 ± 0.06) × 10(12) m(-1) for (69)Ga at room-temperature and 14.1 T. For (75)As, we obtained (3.1 ± 0.1) × 10(12) m(-1). Both values reconcile with earlier results from 77 K and below 1 T, whereas current experiments are at room temperature and 14.1 T. Finally, we present results where few-microsecond pulses of the 2?(0) field induced small (tens of Hz) changes in high-resolution NMR line shapes. There too, spectra collected vs |E| agree with the model for response, further establishing the validity of our protocols to specify |E|. PMID:22047309

Tarasek, Matthew R; Kempf, James G

2011-10-01

194

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

195

Pure-Exchange Solid-State NMR  

NASA Astrophysics Data System (ADS)

Three exchange nuclear magnetic resonance (NMR) techniques are presented that yield 13C NMR spectra exclusively of slowly reorienting segments, suppressing the often dominant signals of immobile components. The first technique eliminates the diagonal ridge that usually dominates two-dimensional (2D) exchange NMR spectra and that makes it hard to detect the broad and low off-diagonal exchange patterns. A modulation of the 2D exchange spectrum by the sine-square of a factor which is proportional to the difference between evolution and detection frequencies is generated by fixed additional evolution and detection periods of duration ?, yielding a 2D pure-exchange (PUREX) spectrum. Smooth off-diagonal intensity is obtained by systematically incrementing ? and summing up the resulting spectra. The related second technique yields a static one-dimensional (1D) spectrum selectively of the exchanging site(s), which can thus be identified. Efficient detection of previously almost unobservable slow motions in a semicrystalline polymer is demonstrated. The third approach, a 1D pure-exchange experiment under magic-angle spinning, is an extension of the exchange-induced sideband (EIS) method. A TOSS (total suppression of sidebands) spectrum obtained after the same number of pulses and delays, with a simple swap of z periods, is subtracted from the EIS spectrum, leaving only the exchange-induced sidebands and a strong, easily detected centerband of the mobile site(s).

deAzevedo, Eduardo R.; Bonagamba, Tito J.; Schmidt-Rohr, Klaus

2000-01-01

196

Pure-exchange solid-state NMR.  

PubMed

Three exchange nuclear magnetic resonance (NMR) techniques are presented that yield (13)C NMR spectra exclusively of slowly reorienting segments, suppressing the often dominant signals of immobile components. The first technique eliminates the diagonal ridge that usually dominates two-dimensional (2D) exchange NMR spectra and that makes it hard to detect the broad and low off-diagonal exchange patterns. A modulation of the 2D exchange spectrum by the sine-square of a factor which is proportional to the difference between evolution and detection frequencies is generated by fixed additional evolution and detection periods of duration tau, yielding a 2D pure-exchange (PUREX) spectrum. Smooth off-diagonal intensity is obtained by systematically incrementing tau and summing up the resulting spectra. The related second technique yields a static one-dimensional (1D) spectrum selectively of the exchanging site(s), which can thus be identified. Efficient detection of previously almost unobservable slow motions in a semicrystalline polymer is demonstrated. The third approach, a 1D pure-exchange experiment under magic-angle spinning, is an extension of the exchange-induced sideband (EIS) method. A TOSS (total suppression of sidebands) spectrum obtained after the same number of pulses and delays, with a simple swap of z periods, is subtracted from the EIS spectrum, leaving only the exchange-induced sidebands and a strong, easily detected centerband of the mobile site(s). PMID:10617438

deAzevedo, E R; Bonagamba, T J; Schmidt-Rohr, K

2000-01-01

197

Phosphorus NMR of isolated perfused morris hepatomas  

SciTech Connect

The authors are developing techniques for the study of perfused solid tumors by NMR. Tissue-isolated solid hepatomas were grown to 1-2 cm diameter as described previously. The arterial supply was isolated and the tumors perfused (0.5 - 1.0 ml/min) in vitro at 25 C with a 15% suspension of red blood cells in Krebs-Henseliet solution. /sup 31/P-NMR spectra were acquired at 162 MHz in a specially-designed NMR probe using a solenoidal coil. Intracellular pH (monitored from the chemical shift of inorganic phosphate) and ATP levels were stable for up to 6 hrs during perfusion. During 30 min of global ischemia, ATP decreased by 75% and pH fell from 7.0 to 6.7. These changes were reversed by 1 hr reperfusion. In addition to ATP and phosphate, the spectra included a large resonance due to phosphomonoesters, as well as peaks consistent with glycerylphosphocholine, glyceryl-phosphoethanolamine, phosphocreatine, NAD, and UDPG. However, the most novel feature of the spectra was the presence of an unidentified peak in the phosphonate region (+ 16.9 ppm). The peak was not present in spectra of muscle, liver, brain, kidney, or fat tissues excised from the same animals. They are presently attempting to identify the compound that gives rise to this peak and to establish its metabolic origin.

Graham, R.A.; Meyer, R.A.; Brown, T.R.; Sauer, L.A.

1986-03-05

198

Protein NMR Structures Refined without NOE Data  

PubMed Central

The refinement of low-quality structures is an important challenge in protein structure prediction. Many studies have been conducted on protein structure refinement; the refinement of structures derived from NMR spectroscopy has been especially intensively studied. In this study, we generated flat-bottom distance potential instead of NOE data because NOE data have ambiguity and uncertainty. The potential was derived from distance information from given structures and prevented structural dislocation during the refinement process. A simulated annealing protocol was used to minimize the potential energy of the structure. The protocol was tested on 134 NMR structures in the Protein Data Bank (PDB) that also have X-ray structures. Among them, 50 structures were used as a training set to find the optimal “width” parameter in the flat-bottom distance potential functions. In the validation set (the other 84 structures), most of the 12 quality assessment scores of the refined structures were significantly improved (total score increased from 1.215 to 2.044). Moreover, the secondary structure similarity of the refined structure was improved over that of the original structure. Finally, we demonstrate that the combination of two energy potentials, statistical torsion angle potential (STAP) and the flat-bottom distance potential, can drive the refinement of NMR structures. PMID:25279564

Ryu, Hyojung; Kim, Tae-Rae; Ahn, SeonJoo; Ji, Sunyoung; Lee, Jinhyuk

2014-01-01

199

NMR properties of petroleum reservoir fluids.  

PubMed

NMR well logging of petroleum reservoir require the measurement of the NMR response of water, oil, and gas in the pore space of rocks at elevated temperatures and pressures. The viscosity of the oil may range from less than 1 cp to greater than 10,000 cp. Also, the oil and gas are not a single component but rather a broad distribution of components. The log mean T1 and T2 relaxation time of dead (gas free) crude oils are correlated with viscosity/temperature and Larmor frequency. The relaxation time of live oils deviate from the correlation for dead crude oils. This deviation can be correlated with the methane content of the oil. Natural gas in the reservoir has components other than methane. Mixing rules are developed to accommodate components such as ethane, propane, carbon dioxide, and nitrogen. Interpretation of NMR logs uses both relaxation and diffusion to distinguish the different fluids present in the formation. Crude oils have a broad spectrum of components but the relaxation time distribution and diffusion coefficient distribution are correlated. This correlation is used to distinguish crude oil from the response of water in the pores of the rock. This correlation can also be used to estimate viscosity of the crude oil. PMID:12850718

Hirasaki, George J; Lo, Sho-Wei; Zhang, Ying

2003-01-01

200

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

201

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

202

Databases and Software for NMR-Based Metabolomics  

PubMed Central

New software and increasingly sophisticated NMR metabolite spectral databases are advancing the unique abilities of NMR spectroscopy to identify and quantify small molecules in solution for studies of metabolite biomarkers and metabolic flux. Public and commercial databases now contain experimental 1D 1H, 13C and 2D 1H-13C spectra and extracted spectral parameters for over a thousand compounds and theoretical data for thousands more. Public databases containing experimental NMR data from complex metabolic studies are emerging. These databases are providing information vital for the construction and testing of new computational algorithms for NMR-based chemometric and quantitative metabolomics studies. In this review we focus on database and software tools that support a quantitative NMR approach to the analysis of 1D and 2D NMR spectra of complex biological mixtures. PMID:24260723

Ellinger, James J.; Chylla, Roger A.; Ulrich, Eldon L.; Markley, John L.

2013-01-01

203

Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization  

Microsoft Academic Search

The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion

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

2003-01-01

204

Quantitative Aspects of 27Al MAS NMR of Calcium Aluminoferrites  

Microsoft Academic Search

27Al MAS NMR spectra of synthetic calcium aluminoferrites, Ca2AlxFe2?xO5 with x = 0.93, 1, 1.33, reveal only a few percent of the expected intensity for the 27Al central transition, indicating that the calcium aluminoferrite phase in Portland cements can barely be observed by 27Al MAS NMR. This result supports the use of 27Al MAS NMR for quantitative analysis of the

Jørgen Skibsted; Hans J. Jakobsen; Christopher Hall

1998-01-01

205

Ultrasound Recycling of Natural Rubber, Characterized with NMR Techniques  

Microsoft Academic Search

We have used ^1H NMR transverse relaxation and pulsed-gradient spin-echo self-diffusion measurements at 70^oC, and ^13C solids NMR, to study molecular and segmental mobilities in natural rubber before and after crosslinking, and after subsequent devulcanization using intense ultrasound. NMR relaxation does not distinguish entanglements and crosslinks, but unentangled sol is evident as a long T2 component. Ultrasound reactor settings affect

J. C. Massey; J. L. Massey; E. von Meerwall; C.-K. Hong; A. Isayev

1999-01-01

206

Effective charge of bovine serum albumin determined by electrophoresis NMR  

Microsoft Academic Search

The effective charge of bovine serum albumin in aqueous solution is determined by dynamic NMR as a function of pH. The effective charge results from the degree of dissociation varying with pH and the local counterion condensation. While the hydrodynamic friction is determined from the diffusion coefficient measured by pulsed-field gradient NMR, the electrophoretic mobility is determined by electrophoresis NMR.

Ute Böhme; Ulrich Scheler

2007-01-01

207

Advances of unilateral mobile NMR in nondestructive materials testing.  

PubMed

Unilateral mobile NMR employs portable instrumentation with sensors, which are applied to the object from one side. Based on the principles of well-logging NMR, a hand-held sensor, the NMR-MOUSE (MObile Universal Surface Explorer) has been developed for nondestructive materials testing. In the following, a number of new applications of unilateral NMR in materials science are reviewed. They are the state assessment of polyethylene pipes, the characterization of wood, the in situ evaluation of stone conservation treatment, high-resolution profiling of rubber tubes and 2-D imaging for defect analysis in rubber products. PMID:15833612

Blümich, Bernhard; Casanova, Federico; Perlo, Juan; Anferova, Sophia; Anferov, Vladimir; Kremer, Kai; Goga, Nicolae; Kupferschläger, Klaus; Adams, Michael

2005-02-01

208

Laser-enhanced NMR spectroscopy: Theoretical considerations  

SciTech Connect

W. S. Warren et al. report that the proton magnetic resonance spectra of chiral molecules are modified slightly by circularly polarized laser light. While it is not unexpected that circularly polarized radiation can influence chiral molecules, the large magnitude of the reported results is surprising. From conservation of parity, and under the conditions of the experiment, the relevant energy shifts per randomly oriented molecule show several simple relations. The chemical shielding of a chiral molecule in right circularly polarized light must be the same as its enantiomer in left circularly polarized light. However, the splitting of nuclear magnetic resonance (NMR) lines in left circular polarization will not necessarily equal that for right circular polarization because of the zero magnetic field term, b[sup 0]I[sub 0]. Direct calculation using the standard Hamiltonian descriptive of the interaction between radiation and matter in a magnetic field shows that for light intensities of 10 W cm[sup [minus]2] the nonchiral chemical shift in the NMR spectrum should yield a value of aI[sub 0] on the order of 10[sup [minus]15] [sigma][sub 0]. The chiral chemical shift, bI[sub 0], is on the order of 10[sup [minus]18] [sigma][sub 0]; for a magnetic field of 10[sup 4] gauss, this intensity-dependent shift corresponds to about 10[sup [minus]15] Hz. The zero magnetic field shift (b[sup 0]I[sub 0]) is about 10[sup [minus]10]Hz. In conclusion, the ordinary manifestation of chirality on light-perturbed chemical shifts is too small to be observed. Shining laser light on a racemic mixture and seeing a single NMR line split into two lines would provide a convincing experimental result. The authors' calculations predict that it will not occur. 3 refs., 1 tab.

Harris, R.A.; Tinoco, I. Jr. (Univ. of California, Berkeley (United States))

1993-02-05

209

NMR measurement of bitumen at different temperatures  

NASA Astrophysics Data System (ADS)

Heavy oil (bitumen) is characterized by its high viscosity and density, which is a major obstacle to both well logging and recovery. Due to the lost information of T2 relaxation time shorter than echo spacing ( TE) and interference of water signal, estimation of heavy oil properties from NMR T2 measurements is usually problematic. In this work, a new method has been developed to overcome the echo spacing restriction of NMR spectrometer during the application to heavy oil (bitumen). A FID measurement supplemented the start of CPMG. Constrained by its initial magnetization ( M0) estimated from the FID and assuming log normal distribution for bitumen, the corrected T2 relaxation time of bitumen sample can be obtained from the interpretation of CPMG data. This new method successfully overcomes the TE restriction of the NMR spectrometer and is nearly independent on the TE applied in the measurement. This method was applied to the measurement at elevated temperatures (8-90 °C). Due to the significant signal-loss within the dead time of FID, the directly extrapolated M0 of bitumen at relatively lower temperatures (<60 °C) was found to be underestimated. However, resulting from the remarkably lowered viscosity, the extrapolated M0 of bitumen at over 60 °C can be reasonably assumed to be the real value. In this manner, based on the extrapolation at higher temperatures (?60 °C), the M0 value of bitumen at lower temperatures (<60 °C) can be corrected by Curie's Law. Consequently, some important petrophysical properties of bitumen, such as hydrogen index ( HI), fluid content and viscosity were evaluated by using corrected T2.

Yang, Zheng; Hirasaki, George J.

2008-06-01

210

NMR measurement of bitumen at different temperatures.  

PubMed

Heavy oil (bitumen) is characterized by its high viscosity and density, which is a major obstacle to both well logging and recovery. Due to the lost information of T2 relaxation time shorter than echo spacing (TE) and interference of water signal, estimation of heavy oil properties from NMR T2 measurements is usually problematic. In this work, a new method has been developed to overcome the echo spacing restriction of NMR spectrometer during the application to heavy oil (bitumen). A FID measurement supplemented the start of CPMG. Constrained by its initial magnetization (M0) estimated from the FID and assuming log normal distribution for bitumen, the corrected T2 relaxation time of bitumen sample can be obtained from the interpretation of CPMG data. This new method successfully overcomes the TE restriction of the NMR spectrometer and is nearly independent on the TE applied in the measurement. This method was applied to the measurement at elevated temperatures (8-90 degrees C). Due to the significant signal-loss within the dead time of FID, the directly extrapolated M0 of bitumen at relatively lower temperatures (<60 degrees C) was found to be underestimated. However, resulting from the remarkably lowered viscosity, the extrapolated M0 of bitumen at over 60 degrees C can be reasonably assumed to be the real value. In this manner, based on the extrapolation at higher temperatures (> or = 60 degrees C), the M0 value of bitumen at lower temperatures (<60 degrees C) can be corrected by Curie's Law. Consequently, some important petrophysical properties of bitumen, such as hydrogen index (HI), fluid content and viscosity were evaluated by using corrected T2. PMID:18387325

Yang, Zheng; Hirasaki, George J

2008-06-01

211

Zur Bestimmung chemischer Verschiebungen der NMR-Frequenzen bei Quadrupolkernen aus den MAS-NMR-Spektren  

Microsoft Academic Search

Die allgemeinen Ausdrücke für den NMR-Zentralübergang für Quadrupolkerne mit halbzahligem Spin bei Probenrotation, die von BEHRENS [1, 2] unter Berücksichtigung von Quadrupolwechselwirkungseffekten 2. Ordnung für beliebige Neigungswinkel der Rotationsachse abgeleitet wurden, werden für den praktisch interessierenden Fall der Probenrotation um den magischen Winkel (magic angle spinning, MAS) in einer den Ausgangsformeln für das Ruhespektrum (ohne Probenrotation) analogen Form dargestellt. Am

D. Müller

1982-01-01

212

MULTIPLE-QUANTUM NMR IN SOLIDS  

SciTech Connect

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

Yen, Y-S.

1982-11-01

213

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

214

Pulsed Gradient Spin-Echo NMR  

NASA Astrophysics Data System (ADS)

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

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

215

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

216

NMR measurements of intracellular ions in hypertension  

NASA Astrophysics Data System (ADS)

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

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

1993-08-01

217

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...

218

Proton NMR Relaxometry of Portland Cement Hydration  

NASA Astrophysics Data System (ADS)

In situ proton NMR relaxometry measurements on the hydration of Portland cement pastes were carried out to follow the hydration process. The spin-spin (T2) relaxation times are about 3 orders of magnitude smaller than the spin-lattice relaxation times (T1), indicating the presence of high amounts of paramagnetic ions. The hydration time dependence of T2 is still determined by the confined nature of exchangeable water in the micropores. T1 evolution with hydration time is dominated by the enhanced self-diffusion due to fast molecular exchange of confined water molecules. A ``hump'' structure is seen in T1 during the middle stages of hydration and is attributed to the development of transient high concentration of polymeric ions in the solution phase. The present NMR investigations provide convincing evidence that even in the presence of high concentrations of paramagnetic impurities, molecular self-diffusion is the principal mechanism governing the spin-lattice relaxation of fluids confined in porous media.

Babu, P. K.; Kirkpatrick, R. James

2010-03-01

219

NMR measurements in solutions of dialkylimidazolium haloaluminates  

SciTech Connect

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

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

1992-06-01

220

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

221

Analysis of macromolecular structures by pulsed NMR  

NASA Astrophysics Data System (ADS)

The T2 spin-spin relaxation curves obtained by pulsed NMR techniques can readily be used to study important features of macromolecular systems quite distinct from their chemical structure. Such features refer to more physical properties such as molecular size, flexibility and mobility, the influence of solvent and temperature on this motion (which is related to viscosity), crystalline fraction and the rate of crystallization, polymerisation and other chemical reactions where there is a considerable change in dimensions etc. It can also serve to determine the degree of crosslinking, where this forms a partial or complete network. However it appears to indicate the presence of a network even when no permanent network is revealed by alternative and well-established techniques such as solubility and swelling which require much longer times. This difference is ascribed to the presence of some intermolecular binding somewhat akin to permanent crosslinks, but of a very shortlived dynamic nature, and this is referred to as due to entanglements between adjacent macromolecules. The T2 measurements reveal their presence if the life-time of these entanglements is comparable or longer than the period ofmeasurement by pulsed NMR. The usual formulae used to determine network formation by permanent crosslinks can be applied to such systems with entanglements or with entanglements plus crosslinks, so that the elastic properties can be determined by NMR T2 measurements. Over a long time only the permanent crosslinks will provide elastic recovery but for sufficiently short times the entanglements provide an additional restoring force and this may be taken to be the cause of the rheological property referred to as creep and viscosity. Since the entanglements but not the permanent crosslinks depend on temperature, many of these physical properties and their variation with temperature can be related directly to the effect of these entanglements as determined by these T2 measurements and derived from pulsed NMR. Another feature which emerges from these investigations is their dependence on solvent where present. The total variation can be ascribed to molecular dimensions and the free volume available for their motion (and hence their freedom to become disentangled). This free volume is influenced by temperature and concentration of solvent where present. The meaning of these T2 responses have been deduced from the changes in pulsed NMR responses to a series of macromolecular systems whose properties have been modified to known extents by known radiation doses. The interpretation of the T2 relaxation patterns obtained from other macromolecular structures now becomes possible. We can therefore hope to see this technique used not only for polymers but especially for biological systems where considerable changes of molecular behaviour such as conformation and motion can result from very minute chemical modifications. Such sensitive features might be for example molecular entanglements and concentration, radiation or chemically-induced crosslinking or degradation (scission), disruption of a regular refolding sequence etc. This T2 technique is particularly suitable for following such changes.

Charlesby, A.

222

NMR OBSERVATION OF PROTON EXCHANGE IN THE CONDUCTING POLYMER POLYANILINE  

E-print Network

solution of pH = 0, and dried under vacuum. They were introduced into an NMR sample holder tube in a dry935 NMR OBSERVATION OF PROTON EXCHANGE IN THE CONDUCTING POLYMER POLYANILINE M. NECHTSCHEIN+ and C the polymer skeleton of polyaniline and adsorbed water. J. Physique 47 (1986) 935-937 juin 1986

Paris-Sud XI, Université de

223

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

224

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

225

Multidimensional spatial-spectral holographic interpretation of NMR photography  

Microsoft Academic Search

A spectral holographic interpretation arises naturally in nuclear magnetic resonance (NMR) photography from either the intrinsic chemical shift anisotropy of the spin system or the field inhomogeneity due to the applied spatial encoding gradients. We can thus think of NMR photography as arising from a “diffraction” off a spatial-spectral holographic grating. The spatial holographic component arises from a high dielectric

Andrew J. M. Kiruluta

2006-01-01

226

Multidimensional spatial-spectral holographic interpretation of NMR photography  

Microsoft Academic Search

A spectral holographic interpretation arises naturally in nuclear magnetic resonance (NMR) photography from either the intrinsic chemical shift anisotropy of the spin system or the field inhomogeneity due to the applied spatial encoding gradients. We can thus think of NMR photography as arising from a ``diffraction'' off a spatial-spectral holographic grating. The spatial holographic component arises from a high dielectric

Andrew J. M. Kiruluta

2006-01-01

227

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.

228

Journal of Biotechnology 77 (2000) 13 NMR in Biotechnology  

E-print Network

.elsevier.com/locate/jbiotec Among the analytical techniques, nuclear mag- netic resonance (NMR) spectroscopy is unique, because for genetic modification and industrial use. Hesse et al. (2000) employ 31 P NMR to measure the intracellular plants will become increasingly important in the agricultural and food industries. Therefore a new area

Hemminga, Marcus A.

229

Historical Perspectives, Encyclopedia of NMR to be submitted Massiot, Dominique  

E-print Network

Historical Perspectives, Encyclopedia of NMR ­ to be submitted Massiot, Dominique : Materials by NMR of Quadrupoles from room to high temperature Dominique Massiot CEMHTI-CNRS, Orléans, France I came California. The former were able to evidence directly local coordination of silicon or aluminum from 29 Si

Paris-Sud XI, Université de

230

Straightforward and complete deposition of NMR data to the PDBe  

PubMed Central

We present a suite of software for the complete and easy deposition of NMR data to the PDB and BMRB. This suite uses the CCPN framework and introduces a freely downloadable, graphical desktop application called CcpNmr Entry Completion Interface (ECI) for the secure editing of experimental information and associated datasets through the lifetime of an NMR project. CCPN projects can be created within the CcpNmr Analysis software or by importing existing NMR data files using the CcpNmr FormatConverter. After further data entry and checking with the ECI, the project can then be rapidly deposited to the PDBe using AutoDep, or exported as a complete deposition NMR-STAR file. In full CCPN projects created with ECI, it is straightforward to select chemical shift lists, restraint data sets, structural ensembles and all relevant associated experimental collection details, which all are or will become mandatory when depositing to the PDB. Instructions and download information for the ECI are available from the PDBe web site at http://www.ebi.ac.uk/pdbe/nmr/deposition/eci.html. Electronic supplementary material The online version of this article (doi:10.1007/s10858-010-9439-3) contains supplementary material, which is available to authorized users. PMID:20680401

Penkett, Christopher J.; van Ginkel, Glen; Velankar, Sameer; Swaminathan, Jawahar; Ulrich, Eldon L.; Mading, Steve; Stevens, Tim J.; Fogh, Rasmus H.; Gutmanas, Aleksandras; Kleywegt, Gerard J.; Henrick, Kim

2010-01-01

231

Development of an integrated detector for NMR microscopy  

Microsoft Academic Search

The development of an integrated detector consisting of a planar microcoil and low noise preamplifier for nuclear magnetic resonance (NMR) microscopy is described. The detector is designed to operate at 500 MHz (11.75 T). These customized detectors may be particularly important for NMR investigations of single cells, where it may become impractical to passively impedance match microcoils with extremely small

J. E. Stocker; T. L. Peck; S. J. Franke; J. Kruse; M. Feng; R. L. Magin

1995-01-01

232

Mobile NMR for porosity analysis of drill core sections  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

233

Multiple quantum NMR dynamics in dipolar ordered spin systems  

NASA Astrophysics Data System (ADS)

We investigate analytically and numerically the multiple-quantum (MQ) NMR dynamics in systems of nuclear spins 1/2 coupled by the dipole-dipole interactions in the case of the dipolar ordered initial state. We suggest two different methods of MQ NMR. One of them is based on the measurement of the dipolar temperature in the quasiequilibrium state which is established after the time of order ?loc-1 ( ?loc is the dipolar local field) after the MQ NMR experiment. The other method uses an additional resonance (?/4)y pulse after the preparation period of the standard MQ NMR experiment in solids. Many-spin clusters and correlations are created faster in such experiments than in the usual MQ NMR experiments and can be used for the investigation of many-spin dynamics of nuclear spins in solids.

Doronin, S. I.; Fel'Dman, E. B.; Kuznetsova, E. I.; Furman, G. B.; Goren, S. D.

2007-10-01

234

NMR screening for rapid protein characterization in structural proteomics.  

PubMed

In the age of structural proteomics when protein structures are targeted on a genome-wide scale, the identification of proteins that are amenable to analysis using x-ray crystallography or NMR spectroscopy is the key to high throughput structure determination. NMR screening is a beneficial part of a structural proteomics pipeline because of its ability to provide detailed biophysical information about the protein targets under investigation at an early stage of the structure determination process. This chapter describes efficient methods for the production of uniformly (15)N-labeled proteins for NMR screening using both conventional IPTG induction and autoinduction approaches in E. coli. Details of sample preparation for NMR and the acquisition of 1D (1)H NMR and 2D (1)H-(15)N HSQC spectra to assess the structural characteristics and suitability of proteins for further structural studies are also provided. PMID:18542882

Hill, Justine M

2008-01-01

235

Synthesis and Characterization of Amphoteric Ligands Including the Crystal and Molecular Structure of ((Me3SiCH2)2InPPh2)2.  

National Technical Information Service (NTIS)

The new amphoteric ligands (Me3SiCH2)2GaPPh2, (Me3SiCH2)2InPPh2, and (Me3CCH2)2InPPh2 have been prepared and characterized by elemental analyses, cryoscopic molecular weight measurements and Hydrogen 1 NMR, Phosphorus 31 NMR and IR spectroscopic data. An ...

O. T. Beachley, J. P. Kopasz, H. Zhang, W. E. Hunter, J. L. Atwood

1986-01-01

236

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

237

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

238

Network glass structure from multidimensional NMR  

SciTech Connect

This paper describes applications of several two-dimensional NMR methods to the study of short-range ordering in inorganic network glasses. In borate, both pure and modified with alkaline oxides, the authors use Dynamic Angle Spinning to extract information about the boron, oxygen, sodium, and rubidium quadrupole coupling interactions, and from them, the distribution of bond angles around the different sites. The authors also discuss the problem of measuring the spin-lattice relaxation times for the different sites. An application of Variable Angle Correlation Spectroscopy to the study of spin-1/2 nuclei such as phosphorus, silver, and selenium in phosphate and chalcogenide glasses is described to directly probe the distribution of chemical shift tensors, and from them, again, the bond angle distribution.

Youngman, R.E.; Olsen, K.K.; Tagg, S.L.; Zwanziger, J.W. [Indiana Univ., Bloomington, IN (United States)

1993-12-31

239

NMR Measurements of Granular Flow and Compaction  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) can be used to measure statistical distributions of granular flow velocity and fluctuations of velocity, as well as spatial distributions of particulate concentration, flow velocity, its fluctuations, and other parameters that may be derived from these. All measurements have been of protons in liquid-containing particles such as mustard seeds or pharmaceutical pills. Our favorite geometry has been the slowly rotating partially filled rotating drum with granular flow taking place along the free surface of the particles. All the above-mentioned parameters have been studied as well as a spatial distribution of particulate diffusion coefficients, energy dissipation due to collisions, as well as segregation of non-uniform mixtures of granular material. Finally, we describe some motions of granular material under periodic vibrations.

Fukushima, Eiichi

1998-03-01

240

NMR solvent peak suppression by nonlinear excitation  

NASA Astrophysics Data System (ADS)

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

Levitt, Malcolm H.

1988-03-01

241

Long Lived NMR Signal in Bone  

E-print Network

Solids and rigid tissues such as bone, ligaments, and tendons, typically appear dark in magnetic resonance imaging (MRI), which is due to the extremely short-lived proton nuclear magnetic resonance (NMR) signals. This short lifetime is due to strong dipolar interactions between immobilized proton spins, which render it challenging to detect these signals with sufficient resolution and sensitivity. Here we show the possibility of exciting long-lived signals in cortical bone tissue with a signature consistent with that of bound water signals. Contrary to long-standing belief, it is further shown that dipolar coupling networks are an integral requirement for the excitation of these long-lived signals. The use of these signals could enhance the ability to visualize rigid tissues and solid samples with high sensitivity, resolution, and specificity via MRI.

Zhang, Boyang; Khitrin, Anatoly; Jerschow, Alexej

2012-01-01

242

Long Lived NMR Signal in Bone  

E-print Network

Solids and rigid tissues such as bone, ligaments, and tendons, typically appear dark in magnetic resonance imaging (MRI), which is due to the extremely short-lived proton nuclear magnetic resonance (NMR) signals. This short lifetime is due to strong dipolar interactions between immobilized proton spins, which render it challenging to detect these signals with sufficient resolution and sensitivity. Here we show the possibility of exciting long-lived signals in cortical bone tissue with a signature consistent with that of bound water signals. Contrary to long-standing belief, it is further shown that dipolar coupling networks are an integral requirement for the excitation of these long-lived signals. The use of these signals could enhance the ability to visualize rigid tissues and solid samples with high sensitivity, resolution, and specificity via MRI.

Boyang Zhang; Jae-Seung Lee; Anatoly Khitrin; Alexej Jerschow

2012-09-18

243

ImatraNMR: novel software for batch integration and analysis of quantitative NMR spectra.  

PubMed

Quantitative NMR spectroscopy is a useful and important tool for analysis of various mixtures. Recently, in addition of traditional quantitative 1D (1)H and (13)C NMR methods, a variety of pulse sequences aimed for quantitative or semiquantitative analysis have been developed. To obtain actual usable results from quantitative spectra, they must be processed and analyzed with suitable software. Currently, there are many processing packages available from spectrometer manufacturers and third party developers, and most of them are capable of analyzing and integration of quantitative spectra. However, they are mainly aimed for processing single or few spectra, and are slow and difficult to use when large numbers of spectra and signals are being analyzed, even when using pre-saved integration areas or custom scripting features. In this article, we present a novel software, ImatraNMR, designed for batch analysis of quantitative spectra. In addition to capability of analyzing large number of spectra, it provides results in text and CSV formats, allowing further data-analysis using spreadsheet programs or general analysis programs, such as Matlab. The software is written with Java, and thus it should run in any platform capable of providing Java Runtime Environment version 1.6 or newer, however, currently it has only been tested with Windows and Linux (Ubuntu 10.04). The software is free for non-commercial use, and is provided with source code upon request. PMID:21705250

Mäkelä, A V; Heikkilä, O; Kilpeläinen, I; Heikkinen, S

2011-08-01

244

Proton NMR Studies of the Conformation of an Octapeptide. An NMR Exercise for Biophysical Chemistry  

NASA Astrophysics Data System (ADS)

We describe an exercise intended to introduce students to the proton NMR experiments used to define the molecular conformation of biological molecules in solution. Proton NMR spectra of the octapeptide [sar1] angiotensin II are assigned and nuclear Overhauser effects are then used to develop constraints that define the three-dimensional shape of the peptide. The exercise demonstrates the utility of COSY, TOCSY, and NOESY types of experiments, while underscoring the limitations of these experiments in the determination of structure. The spectroscopic data used for the exercise are made available in several formats so that an instructor can design variations of the exercise to emphasize particular aspects related to data handling or the generation or comparison of derived structures. At least one quarter of biochemistry and a year of organic chemistry are reasonable prerequisites for the exercise, presuming that these courses provide the needed level of familiarity with the basic concepts of proton NMR spectroscopy. Junior- or senior-level chemistry and biochemistry students are probably most benefited from this exercise.

Rehart, Anne; Gerig, J. T.

2000-07-01

245

Determination of surface relaxivity from NMR diffusion measurements.  

PubMed

Nuclear magnetic resonance (NMR) T2-decay measurements are usually interpreted in terms of pore-size distributions. The T2 relaxation time of a water-wet pore is proportional to the size of the pore via surface relaxivity. Quantitative knowledge of the surface relaxivity is important when T2 spectra are to be used for further use such as NMR derived capillary curves. In this study, we demonstrate that surface relaxivity can be directly determined from NMR measurements. Diffusion of hydrogen spins is restricted by the pore size and this effect is independent of surface relaxivity. Hence, surface relaxivity can be determined by combining restricted diffusion and T2-relaxation. The latter two effects are measured simultaneously in a NMR T2 decay measurement performed in a static magnetic field gradient. This method generalises existing ones for uniform pore systems to full pore-size distributions of realistic rocks. We have performed laboratory NMR diffusion measurements on a number of sandstone core plugs. The surface relaxivities found from these data are compared to those obtained from other methods. This method of measuring surface relaxivity can in principle be applied to NMR data obtained in boreholes which leads to a new application of NMR logging in the characterisation of oil and gas reservoirs. PMID:9803905

Slijkerman, W F; Hofman, J P

1998-01-01

246

[NMR screening in fragment-based drug discovery].  

PubMed

Nuclear magnetic resonance (NMR) is a versatile technique for the pharmaceutical industry. From organic chemistry to MRI, there are a number of applications of NMR. Among them, biomolecular NMR has been used for structure determination of biomolecules and analyzing the interaction between a target protein and its inhibitors. In the context of fragment-based drug discovery (FBDD), NMR has been known as a fragment screening technique, because NMR is good at detecting a weak binding compound in an accurate manner. Generally, the NMR technique for fragment screening is classified into two families: the ligand-based technique and the protein-based technique. The latter technique requires stable isotope labeled protein and also can be applied to a relatively small MW protein target. In the ligand-based technique such as saturation transfer difference (STD) and WaterLOGSY, only the NMR signals of the ligands are observed. The disadvantage of STD and WaterLOGSY is that the non-specific binding is also observed and a competition experiment is required in order to select the specific binding compound. Due to the difference in the consumption of the protein sample, the ligand-based technique has generally been used recently as a primary screening. PMID:20190517

Hanzawa, Hiroyuki; Takizawa, Takeshi

2010-03-01

247

Kubo-Anderson oscillator and NMR of solid state.  

PubMed

The analytical solution for the Kubo-Anderson oscillator with a fluctuating frequency omega for arbitrary distribution function p(omega) has been obtained. The obtained theoretical expression has been applied to consideration of some dynamical problems of solid state NMR, namely (1) dynamical transformation of NMR line shape and spin-echo signal and (2) the temperature transformation of the second moment of NMR line for the case, when the potential barrier for the mobility of magnetic nuclei is a stochastic function of time. PMID:18783926

Sergeev, N A; Olszewski, M

2008-10-01

248

TOPICAL REVIEW: Hyperpolarized xenon in NMR and MRI  

NASA Astrophysics Data System (ADS)

Hyperpolarized gases have found a steadily increasing range of applications in nuclear magnetic resonance (NMR) and NMR imaging (MRI). They can be regarded as a new class of MR contrast agent or as a way of greatly enhancing the temporal resolution of the measurement of processes relevant to areas as diverse as materials science and biomedicine. We concentrate on the properties and applications of hyperpolarized xenon. This review discusses the physics of producing hyperpolarization, the NMR-relevant properties of 129Xe, specific MRI methods for hyperpolarized gases, applications of xenon to biology and medicine, polarization transfer to other nuclear species and low-field imaging.

Oros, Ana-Maria; Shah, N. Jon

2004-10-01

249

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

250

Complete NMR assignments of undegraded asterosaponins from Asterias amurensis.  

PubMed

Four asterosaponins, thornasteroside A (1), versicoside A (2), anasteroside B (3), and asteronylpentaglycoside sulfate (4), were isolated from the predatory starfish Asterias amurensis Lütken. Unlike previous studies focusing on structure elucidation by degradation of the complex saponin molecules, complete nuclear magnetic resonance (NMR) assignment for the intact molecules was accomplished using 600 MHz high magnetic field NMR. The complete set of NMR assignments can help in the structure elucidation of asterosaponins isolated in low yields without resorting to chemical degradation. Furthermore, this approach can be extended to other complex steroidal saponins, which may accelerate the discovery of bioactive secondary metabolites from this invasive starfish species. PMID:24838379

Hwang, In Hyun; Kulkarni, Roshan; Yang, Min Hye; Choo, Soo Jin; Zhou, Wei; Lee, Sang Myung; Jang, Tae Su; Jeong, Gil-Saeng; Chang, Hyeun Wook; Na, MinKyun

2014-10-01

251

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

252

Synthesis of methoxybenzoflavones and assignments of their NMR data.  

PubMed

A phytotoxic root exudate from Acroptilon repens was identified as 7,8-benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6-benzoflavone also is a potent phytotoxin. Six 7,8-benzoflavones and eight 5,6-benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described. PMID:22314503

Hwang, Doseok; Jo, Geunhyeong; Hyun, Jiye; Lee, Sung Dae; Koh, Dongsoo; Lim, Yoongho

2012-01-01

253

NMR Studies of Magnetic and Fast Ionic Conducting Amorphous Borates  

Microsoft Academic Search

NMR studies were performed on lead borate glasses containing significant concentrations of Fe(,2)O(,3) and on lithium borate glasses containing lithium halides (LiCl or LiF). ('11)B and ('207)Pb NMR investigations of glasses in the system x Fe(,2)O(,3)(.)y PbO(.)z B(,2)O(,3) (0 (LESSTHEQ) x (LESSTHEQ) 15.3 Mol %, z\\/y (DOT=) 3) revealed that the NMR line broadening contains Gaussian field-independent and field-dependent components,

Frank Bucholtz

1982-01-01

254

Dynamic NMR study of cyclic derivatives of pyridoxine.  

PubMed

A series of pyridoxine derivatives was investigated by (1) H and 2D nuclear overhauser enhancement spectroscopy (NOESY) NMR. The free energies of activation for the pyridyl-oxygen rotation of the 2,4-dinitrophenyl ether of the seven-membered acetals of pyridoxine were measured by dynamic NMR. A conformational exchange between the chair and twist forms of the seven-membered acetal ring was confirmed by dynamic NMR and STO3G computations. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25139043

Rakhmatullin, I Z; Galiullina, L F; Garipov, M R; Strel'nik, A D; Shtyrlin, Y G; Klochkov, V V

2014-12-01

255

On the use of ultracentrifugal devices for sedimented solute NMR.  

PubMed

We have recently proposed sedimented solute NMR (SedNMR) as a solid-state method to access biomolecules without the need of crystallization or other sample manipulation. The drawback of SedNMR is that samples are intrinsically diluted and this is detrimental for the signal intensity. Ultracentrifugal devices can be used to increase the amount of sample inside the rotor, overcoming the intrinsic sensitivity limitation of the method. We designed two different devices and we here report the directions for using such devices and the relevant equations for determining the parameters for sedimentation. PMID:22872367

Bertini, Ivano; Engelke, Frank; Gonnelli, Leonardo; Knott, Benno; Luchinat, Claudio; Osen, David; Ravera, Enrico

2012-10-01

256

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

257

NMR contributions to structural dynamics studies of intrinsically disordered proteins?  

PubMed Central

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

Konrat, Robert

2014-01-01

258

Recent developments in combining LODESR imaging with proton NMR imaging  

NASA Astrophysics Data System (ADS)

We have designed and constructed RF coil assemblies and the appropriate instrumentation for combining proton NMR imaging with LODESR imaging. This has enabled us to collect sequential images from the same sample using both methods. The coil assembly consists of a crossed ellipse coil for LODESR and proton NMR signal detection and a saddle coil for excitation of the ESR resonance. Images have been collected of phantoms containing copper sulphate and Tempol solutions. NMR images were collected (4.3 min) and within 30 s LODESR data collection started (collection time 2.5 min). Only the Tempol solutions are visible in the LODESR images.

Nicholson, I.; Robb, F. J. L.; McCallum, S. J.; Koptioug, A.; Lurie, D. J.

1998-07-01

259

NMR Methods, Applications and Trends for Groundwater Evaluation and Management  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

260

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

261

Spatially encoded strategies in the execution of biomolecular-oriented 3D NMR experiments  

E-print Network

a single transient. 2D protein NMR implementations of this single-scan method have been demonstrated, yet with 3D biomolecular NMR applications. These include a merging of 2D ultrafast NMR principles- mensional (2D) NMR spectroscopy (Jeener 1971; Aue et al. 1976; Ernst et al. 1987). Such methodology intro

Frydman, Lucio

262

Solid state NMR of porous materials : zeolites and related materials.  

PubMed

Solid state NMR spectroscopy applied to the science of crystalline micro- and mesoporous silica materials over the past 10 years is reviewed. A survey is provided of framework structure and connectivity analyses from chemical shift effects of various elements in zeolites including heteroatom substitutions, framework defects and pentacoordinated silicon for zeolites containing fluoride ions. New developments in the field of NMR crystallography are included. Spatial host-guest ordering and confinement effects of zeolite-sorbate complexes are outlined, with special emphasis on NMR applications utilizing the heteronuclear dipolar interaction. The characterization of zeolite acid sites and in situ NMR on catalytic conversions is also included. Finally, the motion of extra-framework cations is investigated in two tutorial cases of sodium hopping in sodalite and cancrinite. PMID:21452082

Koller, Hubert; Weiss, Mark

2012-01-01

263

NMR methods for in-situ biofilm metabolism studies  

SciTech Connect

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

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

2005-09-01

264

High pressure NMR studies of proteins and membranes  

NASA Astrophysics Data System (ADS)

Advanced high resolution NMR spectroscopy, including two-dimensional NMR techniques, combined with the high pressure capability represents a powerful new tool in studies of proteins and membranes. Selected results taken from recent studies illustrate the high information content and the range of problems that can be investigated. Three specific studies dealing with proteins are mentioned: pressure-induced reversible unfolding of lysozyme; investigation of conformation of the pressure-dissociated monomer of Arc repressor, and cold denaturation of several proteins performed at high pressure by taking advantage of the phase diagram of water. A brief overview of the recent multinuclear NMR studies of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) multilamellar aqueous dispersions and sonicated vesicles and DPPC bilayers containing the charged form of local anesthetic tetracaine (TTC) shows the type of unique information that can be obtained from high pressure NMR studies of model membranes.

Jonas, Jiri

1994-07-01

265

International NMR-based Environmental Metabolomics Intercomparison Exercise  

EPA Science Inventory

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

266

Methyl dynamics in crystalline amino acids: MD and NMR.  

PubMed

Correlation times for rotation of deuterated methyls in crystalline leucine, valine, and cyclo-L-alanyl-L-alanine are calculated with molecular dynamics and compared with NMR data. The simulations distinguish between methyls having different steric environments in the crystal, yielding correlation times differing by a factor of up to 30 for methyls within a given crystal. MD and NMR correlation times agree to within a factor of 2. However, averaging over nonequivalent methyls can yield correlation functions that, although actually multiexponential, are well fit by single exponentials. This may have significance for interpreting NMR data; previous NMR data did not distinguish between the methyls in these crystals. Adiabatic rotational barriers calculated with the X-ray structure differ from effective barriers during simulation by up to +/-1 kcal/mol; the difference indicates that dynamical effects have a significant role in determining rotational correlation times. PMID:12759905

Chatfield, David C; Augsten, Alberto; D'Cunha, Cassian; Wong, Sergio E

2003-07-15

267

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

268

A high-pressure NMR probe for aqueous geochemistry.  

PubMed

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

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

2014-09-01

269

Protein MAS NMR methodology and structural analysis of protein assemblies  

E-print Network

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

Bayro, Marvin J

2010-01-01

270

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

271

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

272

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

273

Paths from weak to strong coupling in NMR  

Microsoft Academic Search

J-coupled nuclear magnetic resonance (NMR) spectroscopy in the strong coupling regime at low magnetic field (10-7 T 10-3 T) and at ultralow field (B<10-7 T). We show that several upper and lower boundaries Biup and Bilow of the magnetic field B exist, where the complexity of J-coupled NMR spectra changes in

S. Appelt; F. W. Häsing; U. Sieling; A. Gordji-Nejad; S. Glöggler; B. Blümich

2010-01-01

274

Investigation of porous media structures using NMR restricted diffusion measurements  

E-print Network

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

Miao, Peizhi

2012-06-07

275

Development and application of proton NMR methodology to lipoprotein analysis  

NASA Astrophysics Data System (ADS)

The present thesis describes the development of 1H NMR spectroscopy and its applications to lipoprotein analysis in vitro, utilizing biochemical prior knowledge and advanced lineshape fitting analysis in the frequency domain. A method for absolute quantification of lipoprotein lipids and proteins directly from the terminal methyl-CH3 resonance region of 1H NMR spectra of human blood plasma is described. Then the use of NMR methodology in time course studies of the oxidation process of LDL particles is presented. The function of the cholesteryl ester transfer protein (CETP) in lipoprotein mixtures was also assessed by 1H NMR, which allows for dynamic follow-up of the lipid transfer reactions between VLDL, LDL, and HDL particles. The results corroborated the suggestion that neutral lipid mass transfer among lipoproteins is not an equimolar heteroexchange. A novel method for studying lipoprotein particle fusion is also demonstrated. It is shown that the progression of proteolytically (?- chymotrypsin) induced fusion of LDL particles can be followed by 1H NMR spectroscopy and, moreover, that fusion can be distinguished from aggregation. In addition, NMR methodology was used to study the changes in HDL3 particles induced by phospholipid transfer protein (PLTP) in HDL3 + PLTP mixtures. The 1H NMR study revealed a gradual production of enlarged HDL particles, which demonstrated that PLTP-mediated remodeling of HDL involves fusion of the HDL particles. These applications demonstrated that the 1H NMR approach offers several advantages both in quantification and in time course studies of lipoprotein-lipoprotein interactions and of enzyme/lipid transfer protein function.

Korhonen, Ari Juhani

1998-11-01

276

Ultrasound Recycling of Silicone Rubber, Characterized with NMR Techniques  

Microsoft Academic Search

We have used proton NMR transverse relaxation and pulsed-gradient spin-echo self-diffusion measurements at 70 deg. C to study molecular and segmental mobilities in poly (dimethyl siloxane) rubber before and after crosslinking, and after subsequent devulcanization by intense ultrasound. Transverse NMR relaxation cannot clearly distinguish the effects of entanglements and crosslinks. Hence the three distinct components of the T2 decays are

J. C. Parr; E. von Meerwall; S. E. Shim; A. Isayev

2000-01-01

277

Microfabrication of Helmholtz Coils with Integrated Channels for NMR Spectroscopy  

Microsoft Academic Search

A new technology for the microfabrication of Helmholtz microcoils with integrated SU-8 channels for NMR spectroscopy is presented. These Helmholtz microcoils demonstrate superior NMR performance regarding spin excitation uniformity compared to planar microcoils. The improved spin excitation uniformity opens the way to advanced chemical analysis using complex RF-pulse sequences. The fabricated Helmholtz coils have Q-factor greater than 20 due to

K. Ehrmann; N. Saillen; F. Vincent; C. Massin; P.-A. Besse; R. S. Popovic

2006-01-01

278

Fabrication of NMR — Microsensors for nanoliter sample volumes  

Microsoft Academic Search

The fabrication of micro-sensors for NMR-spectroscopy on both glass and GaAs is presented. Planar coils with inner diameter from 50 ?m to 400 ?m including a coplanar wave-guide leading to the bonding pads were combined with a chamber for liquid samples of 200–500 ?m diameter on the backside of the substrate. The microcoil served as a receiver in a1H-NMR experiment

J. Dechow; A. Forchel; T. Lanz; A. Haase

2000-01-01

279

Functional cerebral imaging by susceptibility-contrast NMR  

Microsoft Academic Search

In vivo measurement of cerebral physiology by dynamic contrast-enhanced NMR is demonstrated. Time-resolved images of the cerebral transit of paramagnetic contrast agent were acquired using a new ultrafast NMR imaging technique and a novel mechanism of image contrast based on microscopic changes in tissue magnetic susceptibility. Global hypercapnia in dogs was used to establish the relationship between susceptibility-induced signal change

J. W. Belliveau; B. R. Rosen; H. L. Kantor; R. R. Rzedzian; D. N. Kennedy; R. C. McKinstry; J. M. Vevea; M. S. Cohen; I. L. Pykett; T. J. Brady

1990-01-01

280

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

PubMed

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

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

2013-10-18

281

The SPORT-NMR Software: A Tool for Determining Relaxation Times in Unresolved NMR Spectra  

NASA Astrophysics Data System (ADS)

A software package which allows the correct determination of individual relaxation times for all the nonequivalent nuclei in poorly resolved NMR spectra is described. The procedure used, based on the fitting of each spectrum in the series recorded in the relaxation experiment, should improve the analysis of relaxation data in terms of quantitative dynamic information, especially in anisotropic phases. Tests on simulated data and experimental examples concerning 1H and 13C T1?measurement in a solid copolymer and 2H T1Zand T1Qmeasurement in a liquid crystal are shown and discussed.

Geppi, Marco; Forte, Claudia

1999-03-01

282

Using metamaterial yokes in NMR measurements  

NASA Astrophysics Data System (ADS)

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

Allard, Mathieu; Henkelman, R. Mark

2006-10-01

283

Approaches to localized NMR spectroscopy in vivo  

SciTech Connect

Nuclear magnetic resonance (NMR) techniques are developed which allow spatially localized spectra to be obtained from living tissue. The localization methods are noninvasive and exploit the enhanced sensitivity afforded by surface coil probes. Techniques are investigated by computer simulation and experimentally verified by the use of phantom samples. The feasibility and utility of the techniques developed in this research are demonstrated by /sup 31/P spatial localization experiments involving various in vivo organs. In the first part of the thesis, two feasible approaches to localized spectroscopy, which were developed by other laboratories are theoretically analyzed by computer simulation. An alternative approach is provided by the rotating frame zeugmatography experiment which affords chemical-shift spectra displayed as a function of penetration distance into the sample. The further modification of the rotating frame experiment is developed, the Fourier series window (FSW) approach, which utilizes various types of window functions to afford localization in one or a few tissue regions of interest with high sensitivity. Theoretical comparisons with depth pulse methods are also included, along with methods to refine adverse off-resonance behavior.

Garwood, M.G.

1985-01-01

284

NMR Studies of Enzyme Structure and Mechanism  

NASA Astrophysics Data System (ADS)

At least three NMR methodologies pioneered by Al Redfield, have greatly benefited enzymology: (1) the suppression of strong water signals without pre-saturation; (2) sequence specific NH/ND exchange; and (3) dynamic studies of mobile loops of proteins. Water suppression has enabled us to identify unusually short, strong H-bonds at the active sites of five enzymes (three isomerases and two esterases), and to measure their lengths from both the chemical shifts and D/H fractionation factors of the deshielded protons involved (J. Mol. Struct. 615, 163 (2002)). Backbone NH exchange studies were used to detect regions of an NTP pyrophosphohydrolase in which NH groups became selectively protected against exchange on Mg(2+) binding, and further protected on product (NMP) binding, thus locating binding sites as well as conformationally linked remote sites (Biochemistry 42, 10140 (2003)). Dynamic studies were used to elucidate the frequency of motion of a flexible loop of GDP-mannose hydrolase (66,000/sec) containing the catalytic base His-124, from exchange broadening of the side chain NH signals of His-124 in the free enzyme. The binding of Mg(2+) and GDP-mannose lock His-124 in position to deprotonate the entering water and complete the reaction.

Mildvan, Albert

2006-03-01

285

Para-hydrogen perspectives in hyperpolarized NMR.  

PubMed

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

Glöggler, Stefan; Colell, Johannes; Appelt, Stephan

2013-10-01

286

Localized in vivo13C NMR spectroscopy of the brain  

PubMed Central

Localized 13C NMR spectroscopy provides a new investigative tool for studying cerebral metabolism. The application of 13C NMR spectroscopy to living intact humans and animals presents the investigator with a number of unique challenges. This review provides in the first part a tutorial insight into the ingredients required for achieving a successful implementation of localized 13C NMR spectroscopy. The difficulties in establishing 13C NMR are the need for decoupling of the one-bond 13C–1H heteronuclear J coupling, the large chemical shift range, the low sensitivity and the need for localization of the signals. The methodological consequences of these technical problems are discussed, particularly with respect to (a) RF front-end considerations, (b) localization methods, (c) the low sensitivity, and (d) quantification methods. Lastly, some achievements of in vivo localized 13C NMR spectroscopy of the brain are reviewed, such as: (a) the measurement of brain glutamine synthesis and the feasibility of quantifying glutamatergic action in the brain; (b) the demonstration of significant anaplerotic fluxes in the brain; (c) the demonstration of a highly regulated malate-aspartate shuttle in brain energy metabolism and isotope flux; (d) quantification of neuronal and glial energy metabolism; and (e) brain glycogen metabolism in hypoglycemia in rats and humans. We conclude that the unique and novel insights provided by 13C NMR spectroscopy have opened many new research areas that are likely to improve the understanding of brain carbohydrate metabolism in health and disease. PMID:14679498

Gruetter, Rolf; Adriany, Gregor; Choi, In-Young; Henry, Pierre-Gilles; Lei, Hongxia; Oz, Gulin

2006-01-01

287

High resolution NMR spectroscopy in the Earth's magnetic field  

NASA Astrophysics Data System (ADS)

High resolution nuclear magnetic resonance (NMR) spectroscopy at high magnetic fields has developed into a most powerful tool for the determination of molecular structures. The dream is a mobile molecular low field NMR scanner which allows the determination of molecular structures. Until to now at low magnetic fields NMR spectroscopy suffers from the low signal to noise ratio (S/N) and from the lack of access to chemical information in terms of chemical shifts and homo-nuclear J-couplings. We demonstrate that chemical analysis of liquids is possible by mobile ultrahigh-resolution ^1H, ^19F and ^129Xe NMR spectroscopy in the Earth's magnetic field. The ^129Xe chemical shift in liquids is determined in the Earth's magnetic field with a precision comparable to that obtained by superconducting magnets. The ^1H and ^19F NMR spectra allow the determination of hetero-nuclear J-coupling constants with an accuracy of a few mHz. Very fine details of the molecular structure which are not observable with conventional superconducting magnets can be discriminated. For molecules where a rare spin such as carbon ^13C is present the high-resolution low-field ^1H NMR spectrum indeed reveal all hetero- and homo-nuclear J-couplings. All these results open the door for the mobile study of molecular structures as well as for the online monitoring of chemical reactions at ultra-low magnetic fields.

Appelt, Stephan

2007-03-01

288

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

289

ECG gated NMR-CT for cardiovascular diseases  

SciTech Connect

The authors applied NMR-CT to cardiac study with ECG gated technique to evaluate the left ventricular (LV) function and compared it with cardiovascular nuclear medicine study (NM). The NMR-CT machine has resistive air-core magnet with 0.15 Tesla. The saturation recovery image or inversion recovery image were obtained as 256 x 256 matrix and 15 mm in thickness. The study population was ten patients who were evaluated both by NMR image and by NM performed within one week interval. The heart muscle was able to be visualized without any contrast material nor radioisotopes in inversion recovery images, whereas saturation recovery images failed to separate heart muscle from blood pool. The wall motions of LV in both methods were well correlated except for inferior wall. The values of ejection fraction in NMR image were moderately low, but two modalities showed satisfactory correlation (r=0.85). The region of myocardial infarction was revealed as wall thinning and/or wall motion abnormality. It is still preliminary to draw a conclusion, however, it can be said that in the evaluation of LV function, method by NMR might be of equal value to those of NM. It can be certain that eventually gated NMR-CT will become more effective method for various aspects of cardiovascular evaluation.

Nishikawa, J.; Machida, K.; Iio, M.; Yoshimoto, N.; Sugimoto, T.; Kawaguchi, H.; Mano, H.

1984-01-01

290

Nanoscale NMR Spectroscopy and Imaging of Multiple Nuclear Species  

E-print Network

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

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

2014-06-12

291

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

292

NMR-spectroscopic analysis of mixtures: from structure to function  

PubMed Central

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

Forseth, Ry R.; Schroeder, Frank C.

2010-01-01

293

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

294

Transport, Compartmentation, and Metabolism of Homoserine in Higher Plant Cells . Carbon13- and Phosphorus31Nuclear Magnetic Resonance Studies  

Microsoft Academic Search

The transport, compartmentation, and metabolism of homoserine was characterized in two strains of meristematic higher plant cells, the dicotyledonous sycamore (Acer pseudoplatanus) and the mono- cotyledonous weed Echinochloa colonum. Homoserine is an inter- mediate in the synthesis of the aspartate-derived amino acids me- thionine, threonine (Thr), and isoleucine. Using 13C-nuclear magnetic resonance, we showed that homoserine actively entered the cells

Serge Aubert; Gilles Curien; Richard Bligny; Elisabeth Gout; Roland Douce

1998-01-01

295

1H NMR spectroscopic studies of selenosubtilisin.  

PubMed

Anomalously low-field signals in 1H NMR spectra of serine proteases provide valuable information on the protonation state of the catalytic histidine residue. We have examined the pH dependence of the deshielded protons of three different oxidation states of selenosubtilisin, a semisynthetic selenoenzyme with significant peroxidase activity, in order to evaluate the influence of the selenium prosthetic group on the hydrogen-bonding network in the modified active site. In the spectra of the anionic seleninate and selenolate derivatives, two resonances were observed at 18.0 and 15.5/14.0 ppm, assigned respectively to the N delta 1 and N epsilon 2 protons of protonated His64. These signals were apparent from pH 4 to above pH 10, indicating that the negatively charged prosthetic group increases the stability of the imidazolium dramatically, raising its pKa by at least 3-4 pH units. In contrast, a neutral selenenyl sulfide species exhibits no deshielded proton signals at 18 ppm at any pH but has a weak signal at 14.1 ppm above pH 7 which was assigned to the N delta 1 imidazole proton of neutral His64. While the pKa of His64 appears normal (approximately 7) in this derivative, the selenenyl sulfide substitution may alter the orientation of the imidazole ring within the active site for steric reasons. Together with data on the influence of pH on peroxidase activity, these results suggest that selenosubtilisin's His64 acts as a general acid facilitating the reduction of the selenenyl sulfide to selenolate by thiols. PMID:8461308

House, K L; Garber, A R; Dunlap, R B; Odom, J D; Hilvert, D

1993-04-01

296

Solid-state NMR characterization of Mowry Formation shales  

SciTech Connect

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

Miknis, F.P.

1992-04-01

297

Solid-state NMR characterization of Mowry Formation shales  

SciTech Connect

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

Miknis, F.P.

1992-04-01

298

Intermediate couplings: NMR at the solids-liquids interface  

NASA Astrophysics Data System (ADS)

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

Spence, Megan

2006-03-01

299

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

300

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

301

High resolution deuterium NMR studies of bacterial metabolism  

SciTech Connect

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

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

1988-12-25

302

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

303

MQ NMR dynamics in dipolar ordered state at negative temperature.  

PubMed

We investigate theoretically the Multiple Quantum (MQ) NMR dynamics at negative absolute temperatures in systems of nuclear spins 1/2 coupled by the dipole-dipole interactions and with the initial conditions determined by the dipolar ordered state. Two different methods of MQ NMR are used. One of them is based on the measurement of the dipolar energy. The other method uses an additional resonance (?/4)y-pulse after the preparation period of the standard MQ NMR experiment. It is shown that at negative temperatures many-spin clusters and spin correlations are created faster, and the intensities of MQ coherences are higher than in the usual MQ NMR experiments. So, the eighth-order MQ coherence in 10-spin system of the cyclopentane molecule appears to be 1.5 times faster and its intensity is four orders higher than at positive temperatures. The proposed MQ NMR methods at negative absolute temperatures can be used for the investigation of many-spin dynamics of nuclear spins in solids. PMID:24992818

Furman, G B; Goren, S D; Meerovich, V M; Sokolovsky, V L

2014-01-01

304

PFG NMR studies of lysine-silica solutions.  

PubMed

The formation process of silica nanoparticles in lysine-silica mixtures was studied using dynamic light scattering (DLS) and pulsed-field gradient (PFG) NMR measurements. (1)H NMR shows line broadening of the lysine resonances during TEOS hydrolysis/nanoparticle formation. Analysis of the TEOS hydrolysis kinetics show that TEOS hydrolysis is the rate-limiting step in particle formation, and has an activation energy of 20.5 kJ/mol. Transverse relaxation measurements show a corresponding decrease in T(2) with TEOS hydrolysis, indicating a reduction in the lysine mobility due to lysine-silica interactions. PFG NMR results indicate a systemic decrease in the self-diffusion coefficient of lysine as particle formation proceeds. The results obtained can be described using a two-state model wherein lysine is either free in solution or bound to the nanoparticles. Analysis of the PFG data of samples made at various temperatures show that lysine coverage upon complete hydrolysis is between 2.5 and 2.8 mmol lysine/kg solution, and insensitive to the heating temperature. PFG NMR shows a linear increase in the amount of bound lysine with increasing lysine content, indicating an increase in the surface area present, i.e. more and smaller particles, with increased lysine content. The PFG NMR results presented give quantitative insights that indicate that while pH is likely the primary driver for the rate of particle formation and particle size, lysine is critical for stabilization of the nanoparticles. PMID:22789802

Li, Xiang; Shantz, Daniel F

2012-10-01

305

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

306

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

2009-01-08

307

Permeability Prediction for Low Porosity Rocks by Mobile NMR  

NASA Astrophysics Data System (ADS)

Estimating permeability from NMR well logs or mobile NMR core scanner data is an attractive method as the measurements can be performed directly in the formation or on fresh cores right after drilling. Furthermore, the method is fast and non-destructive. Compared to T 1 relaxation times, commonly measured T 2 distributions are influenced by external and internal magnetic field gradients. We performed two-dimensional T 1 and T 2 relaxation experiments on samples of Rhaetian sandstone, a rock with low porosity and small pore radii, using a mobile NMR core scanner which operates within a nearly homogeneous static magnetic field. Because small pore sizes are associated with high internal magnetic field gradients, standard methods from NMR logging in the oil industry cannot be applied for accurate permeability prediction. Therefore, a new model theory was developed, which describes the pore radius dependence of the surface relaxivity ? 2 by both an analytical and a more practical empirical equation. Using corrected ? 2 values, permeability can be predicted accurately from the logarithmic mean of the T 2 distribution and the physically based Kozeny-Carman equation. Additional core plug measurements of structural parameters such as porosity, permeability, specific inner surface area and pore radius distributions supported the NMR results.

Pape, H.; Arnold, J.; Pechnig, R.; Clauser, C.; Talnishnikh, E.; Anferova, S.; Blümich, B.

2009-07-01

308

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

309

NMR structure improvement: A structural bioinformatics & visualization approach  

NASA Astrophysics Data System (ADS)

The overall goal of this project is to enhance the physical accuracy of individual models in macromolecular NMR (Nuclear Magnetic Resonance) structures and the realism of variation within NMR ensembles of models, while improving agreement with the experimental data. A secondary overall goal is to combine synergistically the best aspects of NMR and crystallographic methodologies to better illuminate the underlying joint molecular reality. This is accomplished by using the powerful method of all-atom contact analysis (describing detailed sterics between atoms, including hydrogens); new graphical representations and interactive tools in 3D and virtual reality; and structural bioinformatics approaches to the expanded and enhanced data now available. The resulting better descriptions of macromolecular structure and its dynamic variation enhances the effectiveness of the many biomedical applications that depend on detailed molecular structure, such as mutational analysis, homology modeling, molecular simulations, protein design, and drug design.

Block, Jeremy N.

310

/sup 31/P-NMR study of borophosphate glasses  

SciTech Connect

It is shown that /sup 31/P nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) discriminates among different types of PO/sub 4/ units occurring in borophosphate glasses. The isotope /sup 31/P chemical shift of the PO/sub 4/ increases by nearly 70 ppm in going from the branching unit, neutral and covalently bonded, to the monomeric unit, which carries a -3 nominal charge. By using both stationary and MAS /sup 31/P spectra, the authors also obtain the average values, and distribution widths, for chemical shift anisotropy and the asymmetry factor of PO/sub 4/ units occurring in vitreous borophosphates. Analysis of these NMR spectra provides detailed information about the short-range order in these glasses. It is also shown that the /sup 31/P-NMR-MAS technique may contribute significantly to phase separation and crystallization studies of phosphorus-containing glasses.

Villa, M.; Carduner, K.R.; Chiodelli, G.

1987-07-01

311

A 31P-NMR study of borophosphate glasses  

NASA Astrophysics Data System (ADS)

It is shown that 31P nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) discriminates among different types of PO 4 units occurring in borophosphate glasses. The isotropic 31P chemical shift of the PO 4 increases by nearly 70 ppm in going from the "branching unit," neutral and covalently bonded, to the "monomeric unit," which carries a -3 nominal charge. By using both stationary and MAS 31P spectra, we also obtain the average values, and distribution widths, for chemical shift anisotropy and the asymmetry factor of PO 4 units occurring in vitreous borophosphates. Analysis of these NMR spectra provides detailed information about the short-range order in these glasses. It is also shown that the 31P-NMR-MAS technique may contribute significantly to phase separation and crystallization studies of phosphorus-containing glasses.

Villa, Marco; Carduner, Keith R.; Chiodelli, Gaetano

1987-07-01

312

NMR study in sodium-hydrogen-C{sub 60} superconductor  

SciTech Connect

{sup 23}Na and {sup 1}H NMR studies have been carried out for a Na{sub x}H{sub y}C{sub 60} superconductor. The peak position of the {sup 23}Na NMR spectrum exhibits discontinuous upfield shift of 30 ppm at about 250 K, indicates a first order phase transition. From the line shape of the {sup 23}Na spectrum obtained at 7 K, the quadrupole coupling constant tensor is evaluated to be {vert_bar}e{sup 2}Qq/h{vert_bar} = 3.7 MHz with the asymmetry parameter {eta} = 0.95. The {sup 1}H NMR spectrum suggests an anionic hydrogen state with weakly delocalized nature.

Ogata, H.; Miyajima, S.; Imaeda, K.; Inokuchi, H. [Inst. for Molecular Science, Myodaiji, Okazaki (Japan)

1998-12-31

313

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

314

Detection of free chloride in concrete by NMR  

SciTech Connect

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

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

2004-03-01

315

NMR imaging of cell phone radiation absorption in brain tissue  

PubMed Central

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

Gultekin, David H.; Moeller, Lothar

2013-01-01

316

Solid state NMR and protein-protein interactions in membranes.  

PubMed

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

2013-12-01

317

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

318

NMR of bent-core nematogens: a mini-review.  

PubMed

This review focuses on two of our studied bent-core liquid crystals 2-methyl-3-[4-(4-octylbenzoyloxy)-benzylidene]-amino-benzoic acid 4-(4-dodecylphenylazo)-phenyl ester A131, and a shape-persistent fluorenone mesogen, F1a by means of temperature-dependent (13) C NMR spectra and deuterium NMR spectra, respectively. Orientational order parameters, molecular packing, and/or conformations in the nematic phases or nematic glass can be extracted from the observed NMR spectra. These will be discussed in terms of certain motional models. In particular, F1a has been found to form a biaxial nematic glass. The derived orientational order parameters would put the biaxial system of phase symmetry lower than orthorhombic. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24975632

Figueirinhas, João L; Dong, Ronald Y

2014-10-01

319

NMR imaging of cell phone radiation absorption in brain tissue.  

PubMed

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

Gultekin, David H; Moeller, Lothar

2013-01-01

320

NMR investigations of tetrapropylammonium aluminosilicate and borosilicate solutions  

SciTech Connect

{sup 29}Si, {sup 27}Al, and {sup 11}B NMR spectroscopies were used to characterize dilute, highly alkaline tetrapropylammonium (TPA) aluminosilicate and borosilicate solutions. The compositions of the solutions range from 0.1 to 2 mol % SiO{sub 2}, silicate ratios (R = (SiO{sub 2})/(M{sub 2}O); M{sup +} = TPA{sup +}) from 0.1 to 2, and Si/Al or Si/B molar ratios from 0.25 to 10. {sup 29}Si and {sup 27}Al NMR spectra provide evidence for the formation of aluminosilicate anions. Si is observed with Q{sub 1}(A1Al), Q{sub 2{minus}Delta}(1Al), Q{sub 2}(1Al) + Q{sub 3{Delta}}(1Al), and Q{sub 3}(1Al) connectivity. Several new {sup 29}Si NMR peaks are assigned to specific aluminosilicate anions based on chemical shifts. {sup 27}Al NMR spectra of aluminosilicate solutions reveal peaks corresponding to Al bound to zero, one, two, and three siloxane bonds. The distribution of aluminosilicate anions is affected by the concentration of dissolved Si and Al, as well as the solution pH. The distribution of aluminosilicate species is described in terms of simple chemical equilibria. {sup 29}Si and {sup 11}B NMR spectra of borosilicate solutions indicate that borate anions are less reactive than aluminate anions. {sup 11}B NMR spectra reveal only a small fraction of the dissolved B appears to form borosilicates.

Mortlock, R.F.; Bell, A.T.; Radke, C.J. (Univ. of California, Berkeley (USA))

1991-01-10

321

MVAPACK: a complete data handling package for NMR metabolomics.  

PubMed

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

Worley, Bradley; Powers, Robert

2014-05-16

322

Solid-State NMR on Polymers under Mechanical Stress  

NASA Astrophysics Data System (ADS)

Low-field NMR in a Halbach magnet has been used for the in-situ investigation of polymers under mechanical stress. Low-field NMR at a Larmor frequency of 32 MHz is particularly suited for the investigation of magnetic resonance relaxation and residual dipolar couplings. The method has been demonstrated on an elastomer and has subsequently been applied to a semicrystalline polymer. Under uniaxial load the transverse relaxation T2 becomes faster and residual dipolar couplings are getting stronger. The effect on the elastomer is completely reversible, while in the semicrystalline polymer an irreversible rearrangement is observed.

Böhme, Ute; Gelfert, Karsten; Scheler, Ulrich

2011-03-01

323

NMR spectra and structures of oridonin derivatives complexes with ?-cyclodextrin.  

PubMed

Complexations between three oridonin derivatives and ?-cyclodextrin (?CD) were studied by nuclear magnetic resonance (NMR) method. Job's plots for complexes were depicted by (1) H NMR spectra chemical shifts, which proved the 1:1 stoichiometry inclusion complex formation between each derivative and ?CD. Two-dimensional rotating frame overhauser effect spectroscopy (2D ROESY) support the above conclusion and also proved that ring A of each oridonin derivative deeply enters into hydrophobic cavity from the wider rim and the other parts are outside the cavity. Apparent formation constants (Ka ) of complexes between three oridonin derivatives and two CDs are calculated according to Scott's equation. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21815208

Liu, Wei; Zhao, Bing; Li, Yin-Chao; Liu, Hong-Min

2011-09-01

324

Quantitative determination of cephalexin in cephradine by NMR spectroscopy.  

PubMed

An NMR method to determine quantitatively the presence of cephalexin in cephradine was developed. The method is applicable to the chemical itself as well as to capsules and oral suspension formulations. The determination is based on the NMR signal arising from the five aromatic protons of the cephalexin molecule. Integration of this signal relative to a signal from cephradine provides the data necessary to determine the percentage of cephalexin present. The precision at the 2% cephalexin levels is +/- 0.18%. The time required to carry out a single analysis is about 10 min, and five analyses can be done in about 0.5 hr. PMID:702311

Warren, R J; Zarembo, J E; Staiger, D B; Post, A

1978-10-01

325

NMR Studies of Magnetic and Fast Ionic Conducting Amorphous Borates.  

NASA Astrophysics Data System (ADS)

NMR studies were performed on lead borate glasses containing significant concentrations of Fe(,2)O(,3) and on lithium borate glasses containing lithium halides (LiCl or LiF). ('11)B and ('207)Pb NMR investigations of glasses in the system x Fe(,2)O(,3)(.)y PbO(.)z B(,2)O(,3) (0 (LESSTHEQ) x (LESSTHEQ) 15.3 Mol %, z/y (DOT=) 3) revealed that the NMR line broadening contains Gaussian field-independent and field-dependent components, and field-dependent Lorentzian components, resulting in broadening lineshapes of the Voight type. The ('11)B NMR linewidth data were in excellent agreement with a model which assumes the Fe atoms are distributed uniformly and isotropically throughout the glass matrix, and suggests the absence of significant concentrations of B-Fe linkages in these glasses. While the ('11)B NMR linewidth and magnetic susceptibility data vary smoothly and monotonically over the sample composition range, the density, N(,4) (fraction of 4-coordinated borons), and ('207)Pb NMR absorption peak position display evidence of two-region behavior with the break between regions near 4 Mol % Fe(,2)O(,3). The NMR data is interpreted in terms of changes in the borate network. The results of N(,4) and ('11)B NMR lineshape measurement performed on the fast ionic conducting lithium flouroborate (Li(,2)O-Li(,2)F(,2)-B(,2)O(,3)) and lithium chloroborate (Li(,2)O-Li(,2)Cl(,2)-B(,2)O(,3)) glass systems were found to be in excellent agreement with a model which assumes that the types and quantities of borate configurations present in the glasses are totally unaffected by the presence of the lithium halide species. The model employs a semi -empirical theory of the borate network developed for the binary Li(,2)O-B(,2)O(,3) system and predicts that N(,4) should depend entirely on R = Mol % Li(,2)O)/(Mol % B(,2)O(,3)). This agreement suggests that the lithium halide enters the glass network interstitially.

Bucholtz, Frank

326

Aluminum27 NMR Investigations of Aqueous and Methanolic Aluminosilicate Solutions  

Microsoft Academic Search

Aluminum-27 NMR spectroscopy was used to characterize aqueous and methanolic alkaline solutions of tetramethylammonium (TMA) aluminosilicates. Aluminosilicate solutions have been prepared with different concentrations of silicon [0.577–1.24% (w\\/w)], aluminum [0.0022–0.239% (w\\/w)], methanol [0.0–0.70% (w\\/w)] and H2O [0.23–90% (w\\/w)]. All solutions contain the same ratio of Si\\/TMA = 1 and Si\\/Al molar ratios between 0.5 and 25.27Al NMR spectra of TMA

Abdolraouf Samadi-Maybodi; Nasser Goudarzi; Hamidreza Bijanzadeh

2005-01-01

327

Alkoxohydridoaluminates: multinuclear NMR study of sodium hydrido-(2-methoxyethoxo) aluminates  

Microsoft Academic Search

23Na, 27Al, and 1H NMR spectra were obtained on benzene solutions of varying sodium alkoxohydridoaluminate compositions, Na+HxAl?(OR)4?x, where x = 2 to 0, and OR = OCH2CH2OCH3. An extensive series was prepared by titration of initial Na+H2Al(OR)2?, (SDMA), x = 2, by 2-methoxyethanol, HOCH2CH2OCH3.The NMR data presented enabled the refinement of the structure of SDMA, sodium dihydrido-bis(2-methoxyethoxo)aluminate, proposed formerly as

Z. ?erný; J. Fusek; J. Machá?ek; O. K?íž; B. ?ásenský

1996-01-01

328

NMR investigations of tetrapropylammonium aluminosilicate and borosilicate solutions  

Microsoft Academic Search

²⁹Si, ²⁷Al, and ¹¹B NMR spectroscopies were used to characterize dilute, highly alkaline tetrapropylammonium (TPA) aluminosilicate and borosilicate solutions. The compositions of the solutions range from 0.1 to 2 mol % SiOâ, silicate ratios (R = (SiOâ)\\/(MâO); M{sup +} = TPA{sup +}) from 0.1 to 2, and Si\\/Al or Si\\/B molar ratios from 0.25 to 10. ²⁹Si and ²⁷Al NMR

R. F. Mortlock; Alexis T. Bell; C. J. Radke

1991-01-01

329

A flow velocity zeugmatographic interlace for NMR imaging in humans.  

PubMed

We describe a flow sensitizing zeugmatographic phase-modulation interlace for NMR-imaging which is exactly analogous to Lauterbur's spatial-location-sensitizing magnetic field gradients. The method may be implemented by minor modification of any NMR-imaging scanner without interfering with its conventional operation, and enables up to 6-D imaging of the joint (spatial-flow) density of spins delta (r,v). In a special simplification, specific-flow-density, mean value of v(r), and flow-current-specific-flow-density, rho 0(r)v, derive directly from "real' and "imaginary" parts of the image reconstruction. PMID:6927206

Moran, P R

1982-01-01

330

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

331

14N magic angle spinning overtone NMR spectra  

NASA Astrophysics Data System (ADS)

We present the first 14N overtone NMR spectra obtained directly under magic angle spinning conditions. Line-broadening contributions from chemical shift anisotropy and heteronuclear dipolar couplings are significantly reduced, and, despite theoretical predictions, spinning sidebands are minimal, leaving second-order quadrupolar powder patterns with narrow discontinuities that can be observed using a single excitation pulse. We also show that the limited bandwidth and offset-dependent nutation rates exhibited by standard RF pulses can be overcome using frequency-swept pulses, allowing the direct acquisition of solid-state 14N NMR spectra in which multiple nitrogen sites are well-resolved.

O'Dell, Luke A.; Ratcliffe, Christopher I.

2011-09-01

332

Filter-exchange PGSE NMR determination of cell membrane permeability  

NASA Astrophysics Data System (ADS)

A new PGSE NMR sequence is introduced for measuring diffusive transport across the plasma membrane of living cells. A "diffusion filter" and a variable mixing time precedes a standard PGSE block for diffusion encoding of the NMR signal. The filter is a PGSE block optimized for selectively removing the magnetization of the extracellular water. With increasing mixing time the intra- and extracellular components approach their equilibrium fractional populations. The rate of exchange can be measured using only a few minutes of instrument time. Water exchange over the plasma membrane of starved yeast cells is studied in the temperature range +5 to +32 °C.

Åslund, Ingrid; Nowacka, Agnieszka; Nilsson, Markus; Topgaard, Daniel

2009-10-01

333

NMR T2 Inversion along the Depth Dimension  

NASA Astrophysics Data System (ADS)

The spurious signals in NMR logging often cause neighboring depth intervals of the same rock type to have dissimilar T2 distributions and oscillatory porosity responses. We found that we can use the 2D NMR concept to jointly invert T2 distributions of sequential depth records using the depth as the extra dimension and basis functions as the regularizing tool for smoothing, thereby constraining the solutions to have a reasonable behavior. Our results show fluctuation of both porosity and shape of T2 distribution is reduced. Such practice increases the feasibility of using T2 distribution as a rock type indicator.

Sun, Boqin; Skalinski, Mark; Dunn, Keh-Jim

2008-12-01

334

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

335

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

336

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

EPA Science Inventory

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

337

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

E-print Network

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

Torres-Verdín, Carlos

338

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

339

Combined 17O NMR and 11B– 31P double resonance NMR studies of sodium borophosphate glasses  

Microsoft Academic Search

17O enriched sodium borophosphate glasses were prepared from isotopically enriched NaPO3 and H3BO3. These glasses have been studied by 17O, 11B and 31P NMR including 17O and 11B multiple quantum magic angle sample spinning (MQMAS), 11B–31P heteronuclear correlation (HETCOR) NMR and 11B{31P} rotational echo double resonance (REDOR). For comparison, the crystalline borophosphates BPO4 and Na5B2P3O13 were included in the investigations.

Michaela Zeyer-Düsterer; Lionel Montagne; Gérard Palavit; Christian Jäger

2005-01-01

340

Comparison of the 89Y NMR with the 17O NMR in YBa 2Cu 3O 6+x  

NASA Astrophysics Data System (ADS)

The 89Y NMR shifts in YBa 2Cu 3O 6+x are compared with the 17O NMR new data published by Yoshinari, Yasuoka et al., and it is shown that the relation T1TKs=const. is realized for 89Y nuclei. The angular dependence of 17(1/T 1) measured by Barriquand et al. in YBa 2Cu 3O 6.5 is analyzed. The anisotropy of the energy width of dynamical spin susceptibility with q?0, ? 17? 0 is discussed.

Ohno, Takashi; Mizuno, Kiyoshi; Kanashiro, Tatsuo; Alloul, Henri

1991-12-01

341

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

Microsoft Academic Search

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

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

2007-01-01

342

Portable, low-cost NMR with laser-lathe lithography produced microcoils  

Microsoft Academic Search

Nuclear Magnetic Resonance (NMR) is unsurpassed in its ability to non-destructively probe chemical identity. Portable, low-cost NMR sensors would enable on-site identification of potentially hazardous substances, as well as the study of samples in a variety of industrial applications. Recent developments in RF microcoil construction (i.e. coils much smaller than the standard 5mm NMR RF coils), have dramatically increased NMR

Vasiliki Demas; Julie L. Herberg; Vince Malba; Anthony Bernhardt; Lee Evans; Christopher Harvey; Sarah C. Chinn; Robert S. Maxwell; Jeffrey Reimer

2007-01-01

343

Interaction of phenol with NaX zeolite as studied by 1H MAS NMR, 29Si MAS NMR and 29Si CP MAS NMR spectroscopy  

Microsoft Academic Search

The interaction of phenol with zeolite NaX has been studied by 1H and 29Si MAS and 29Si-CP-MAS NMR spectroscopy. A large displacement of the chemical shift of hydroxyl protons from 1.2 ppm in the crystalline state to about 9 ppm occurs upon H-bonding of phenol to basic oxygen atoms of the zeolite. An enhancement of the 29Si-CP-MAS signal is observed

T Beutel; M.-J Peltre; B. L Su

2001-01-01

344

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

345

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

346

Fruit ripeness detection by using H sup 1 NMR (Nuclear Magnetic Resonance)  

Microsoft Academic Search

The possibility of detecting ripeness of raw fruit by measuring sugar content with an A-200 Fourier Transform (FT) Nuclear Magnetic Resonance (NMR) was investigated. Then, the samples of sugar-water mixtures and real fruit were tested with the NMR and the correlations of sugar contents to NMR spectra were obtained. Sugar content (or ripeness level) was linearly correlated to the intensity

Seong In Cho; G. W. Krutz

1989-01-01

347

Unique opportunities for NMR methods in structural genomics Gaetano T. Montelione Cheryl Arrowsmith  

E-print Network

Unique opportunities for NMR methods in structural genomics Gaetano T. Montelione � Cheryl of structural genomics Á Functional genomics Á NMR Á Crystallography Á NMR methods Á Protein Structure contribu- tions of structural genomics (SG) for biomedical research, we envision many future opportunities

Powers, Robert

348

Investigation of Structural Information for Boron - Solids and Aluminates via NMR and Nqr Studies  

Microsoft Academic Search

Nuclear Magnetic Resonance (NMR) has been prevailed in investigating local structures for a variety of materials: various oxide glasses, zeolites, superconductors, etc. Since glasses have short range ordered structures instead of long range ordered ones in crystals, NMR is usually more useful in determining the local structures for many glasses than any other detection methods do. Along with NMR, Nuclear

Donghoon Lee

1991-01-01

349

Isotropic and anisotropic chemical shift in 207Pb NMR of inorganic solids  

Microsoft Academic Search

We have recently described empirical correlations between 207Pb NMR chemical shift (oxidation state 2+) and structure in solids (Fayon et al.) that should allow the use of 207Pb NMR as a structural probe in disordered solids of complex composition. These empirical correlations are compared to new experimental NMR data in crystalline lead aluminates and lead silicates. Nous avons récemment développé

F. Fayon; C. Bessada; D. Massiot; I. Farnan; J.-P. Coutures

1998-01-01

350

Calcium and Strontium Hexaluminates: NMR Evidence that "Pentacoordinate" Cation Sites Are Four-Coordinated  

E-print Network

LETTERS Calcium and Strontium Hexaluminates: NMR Evidence that "Pentacoordinate" Cation Sites, high-resolution solid state 27Al NMR data for two members of the magnetoplumbite group of structures of the NMR signal from the Al(2) sites, which have been previously described as "pentacoordinate" but which

Puglisi, Joseph

351

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

E-print Network

the units. Facility design and installation: Design and installation of a new NMR facility requires a number should be considered in the design of and NMR facility. Successful operation of an NMR requires very will be accelerated towards the magnet with great force. Metal belt buckles, steel tipped shoes, medical implants

Maroncelli, Mark

352

Single-Scan NMR Spectroscopy at Arbitrary Dimensions Yoav Shrot and Lucio Frydman*  

E-print Network

a parametric incrementation of their values throughout independent experiments. Two-dimensional (2D) NMR whereby data acquisition in 2D NMR can be parallelized, enabling the collection of complete 2D spectral sets within a single transient. The present paper discusses the extension of this 2D NMR methodology

Frydman, Lucio

353

Relaxation-Assisted Separation of Chemical Sites in NMR Spectroscopy of Static Solids  

E-print Network

. The principles and limitations of the 2D NMR approach resulting from these considerations are discussedRelaxation-Assisted Separation of Chemical Sites in NMR Spectroscopy of Static Solids Adonis sites in the NMR spectroscopy of powdered or disordered samples. This proposal is motivated

Frydman, Lucio

354

Communication HyperSPASM NMR: A new approach to single-shot 2D correlations  

E-print Network

Communication HyperSPASM NMR: A new approach to single-shot 2D correlations on DNP-enhanced samples Available online 29 October 2012 Keywords: 2D NMR Dissolution DNP Hyperpolarization Heteronuclear connectivity, two-dimensional (2D) NMR conveys unique information about a molecule's struc- ture and dynamics

Frydman, Lucio

355

Journal of Biomolecular NMR, 9 (1997) 359369 359 *To whom correspondence should be addressed.  

E-print Network

been measured by 2D NMR methods for the amide and C H proton chemical shifts in two globular proteinsJournal of Biomolecular NMR, 9 (1997) 359­369 359 *To whom correspondence should be addressed. © 1997 Kluwer Academic Publishers. Printed in The Netherlands. J-Bio NMR 437 Temperature dependence of 1

Williamson, Mike P.

356

Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain Investigations  

E-print Network

Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain ultrafast acquisitions of 2D NMR spectra with suitable spectral widths on a microimaging probe (for both Wiley-Liss, Inc. Key words: ultrafast 2D NMR; magnetic resonance spectros- copy; brain metabolites; 2D

Frydman, Lucio

357

Real-Time 2D NMR Identification of Analytes Undergoing Continuous Chromatographic Separation  

E-print Network

Real-Time 2D NMR Identification of Analytes Undergoing Continuous Chromatographic Separation Boaz, with the real-time acquisition of a series of 2D 1 H NMR spectra arising from a mixture of compounds subject to a continuous liquid chromatography (LC) separation. This real-time 2D NMR identification of chemicals eluted

Frydman, Lucio

358

Single-scan 2D NMR spectroscopy on a 25 T bitter magnet Boaz Shapira a  

E-print Network

Single-scan 2D NMR spectroscopy on a 25 T bitter magnet Boaz Shapira a , Kiran Shetty b , William W Abstract 2D NMR relies on monitoring systematic changes in the phases incurred by spin coherences for 2D NMR acquisitions. It is here shown with a series of homo- and hetero-nuclear examples

Frydman, Lucio

359

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan  

E-print Network

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan Yoav out analytical characterizations on chemical and biochemical samples [2,3] 2D NMR probably finds its resonance imaging (MRI). In spite of the dissimilar information being sought in 2D NMR and 2D MRI

Frydman, Lucio

360

Similarity Search for multi-dimensional NMR-Spectra of Natural Products  

E-print Network

of an 2D-NMR experiment can be seen as an inten- sity function measured over two variables3 . Regions struc- ture. The usual visualizations of 2D-NMR spectra are contour plots as shown in figure 1. An ideal of the peaks. Content-based similarity search of 2D- NMR spectra would be a valuable tool for structure

Hinneburg, Alexander

361

Ultrafast Solid-State 2D NMR Experiments via Orientational Encoding Rangeet Bhattacharyya and Lucio Frydman*  

E-print Network

Ultrafast Solid-State 2D NMR Experiments via Orientational Encoding Rangeet Bhattacharyya and Lucio October 6, 2006; E-mail: lucio.frydman@weizmann.ac.il 2D NMR1 enables the characterization of a wide by sensitivity constraints. Proposals for accelerating 2D NMR include among others non-FT schemes3 as well

Frydman, Lucio

362

Communication Single-scan 2D NMR correlations by multiple coherence transfers  

E-print Network

Communication Single-scan 2D NMR correlations by multiple coherence transfers Maayan Gal 1 , Lucio: Multidimensional spectroscopy Ultrafast 2D NMR HSQC Coherence transfer processes a b s t r a c t A new scheme for the acquisition of heteronuclear 2D correlations in NMR spectroscopy within a single scan, is proposed

Frydman, Lucio

363

Sensitivity Enhancement in 1D Heteronuclear NMR Spectroscopy via Single-Scan Inverse  

E-print Network

place.[5] During the development of 2D NMR as a tool for biomolecu- lar investigations; a potential made possible by the advent of spatially encoded acquisition methods capable of providing 2D NMR NMR obser- vations. A well-known solution to this sensitivity problem is indi- rect detection: a 2D

Frydman, Lucio

364

Relaxation-Optimized NMR Spectroscopy of Methylene Groups in Proteins and Nucleic Acids  

E-print Network

can be incorporated in many of today's most common 2D and 3D NMR experiments. As an example, we showRelaxation-Optimized NMR Spectroscopy of Methylene Groups in Proteins and Nucleic Acids Emeric acids is of the methylene type. Their detailed study, however, in terms of structure and dynamics by NMR

Clore, G. Marius

365

Sorting out Mixtures with 2D NMR Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-print Network

Sorting out Mixtures with 2D NMR Gregory S. Boebinger, National High Magnetic Field Laboratory DMR-Award 0654118 AMRIS Facility We developed a 2D NMR peak alignment algorithm that enables pattern recognition of the resonances. The combination of 2D NMR spectra with full-resolution statistical analysis provides a platform

Weston, Ken

366

Principles and Features of Single-Scan Two-Dimensional NMR Spectroscopy  

E-print Network

resonance (2D NMR) provides one of the foremost contemporary tools available for the elucidation of molecular structure, function, and dynamics. Execution of a 2D NMR experiment generally involves scanning various conceptual and experimental aspects of this novel 2D NMR methodology. The basic principles

Frydman, Lucio

367

Quadrupolar and Chemical Shift Tensors Characterized by 2D Multiple-Quantum NMR Spectroscopy  

E-print Network

Quadrupolar and Chemical Shift Tensors Characterized by 2D Multiple-Quantum NMR Spectroscopy Ales The present work discusses a new 2D NMR method for char- acterizing the principal values and relative; multiple-quantum spectroscopy; 2D NMR correlations. 1. INTRODUCTION Quadrupolar nuclei with half

Frydman, Lucio

368

Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy  

E-print Network

Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy Maayan Gal, Mor: An approach enabling the acquisition of 2D nuclear magnetic resonance (NMR) spectra within a single scan has of these measurements involved acquiring a train of 2D 1 H-15 N HSQC NMR spectra separated by ca. 4 s; following

Frydman, Lucio

369

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

2004-01-01

370

Monitoring Mechanistic Details in the Synthesis of Pyrimidines via Real-Time, Ultrafast Multidimensional NMR Spectroscopy  

E-print Network

of nitriles to yield alkylpyrimidines. Up to 2500 2D NMR data sets were thus collected over the course of complex chemical problems such as this one. Two-dimensional (2D) NMR, in particular, could enable one of formation. Doing so, however, requires completing the 2D NMR measurement in time scales compatible

Frydman, Lucio

371

SYLLABUS for CH 841 and CH 841L Chemical Applications of NMR Spectroscopy  

E-print Network

. The second dimension (2D NMR): Quantum- mechanical approach; coherence transfer; phase cycling and coherenceSYLLABUS for CH 841 and CH 841L Fall 2009 Chemical Applications of NMR Spectroscopy Catalog Description: Basic concepts of NMR spectroscopy with application to organic, inorganic, physical

Stuart, Steven J.

372

Symmetric spatial encoding in ultrafast 2D NMR spectroscopy Boaz Shapira, Yoav Shrot, Lucio Frydman *  

E-print Network

Symmetric spatial encoding in ultrafast 2D NMR spectroscopy Boaz Shapira, Yoav Shrot, Lucio Frydman with a series of amplitude-modulated homo- and hetero-nuclear 2D ultrafast NMR examples. Ã? 2005 Elsevier Inc. All rights reserved. Keywords: Ultrafast 2D NMR; Spatial encoding; Double-frequency-sweep irradiation

Frydman, Lucio

373

Two-Dimensional Dynamic-Director 13 C NMR of Liquid Crystals  

E-print Network

director, in synchrony with the acquisition of a 2D chemical shift correlation spectrum. By monitoringTwo-Dimensional Dynamic-Director 13 C NMR of Liquid Crystals Dan McElheny, Min Zhou, and Lucio resonance (NMR) experiment for facilitating the resolution and assignment of liquid crystalline 13 C NMR

Frydman, Lucio

374

A fast NMR method for resonance assignments: application to metabolomics.  

PubMed

We present a new method for rapid NMR data acquisition and assignments applicable to unlabeled ((12)C) or (13)C-labeled biomolecules/organic molecules in general and metabolomics in particular. The method involves the acquisition of three two dimensional (2D) NMR spectra simultaneously using a dual receiver system. The three spectra, namely: (1) G-matrix Fourier transform (GFT) (3,2)D [(13)C, (1)H] HSQC-TOCSY, (2) 2D (1)H-(1)H TOCSY and (3) 2D (13)C-(1)H HETCOR are acquired in a single experiment and provide mutually complementary information to completely assign individual metabolites in a mixture. The GFT (3,2)D [(13)C, (1)H] HSQC-TOCSY provides 3D correlations in a reduced dimensionality manner facilitating high resolution and unambiguous assignments. The experiments were applied for complete (1)H and (13)C assignments of a mixture of 21 unlabeled metabolites corresponding to a medium used in assisted reproductive technology. Taken together, the experiments provide time gain of order of magnitudes compared to the conventional data acquisition methods and can be combined with other fast NMR techniques such as non-uniform sampling and covariance spectroscopy. This provides new avenues for using multiple receivers and projection NMR techniques for high-throughput approaches in metabolomics. PMID:24488481

Pudakalakatti, Shivanand M; Dubey, Abhinav; Jaipuria, Garima; Shubhashree, U; Adiga, Satish Kumar; Moskau, Detlef; Atreya, Hanudatta S

2014-03-01

375

Consistent blind protein structure generation from NMR chemical shift data  

E-print Network

School, Piscataway, NJ 08854; §Departments of Chemistry and Structural Biology and Northeast Structural majority of current protein NMR structure studies today rely on the expression of recombinant protein with uniform enrichment of 13 C and 15 N stable isotopes. The first stage of the structure determination

Baker, David

376

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

E-print Network

. A spin's magnetic moment experiences a torque, causing precession. B 0 M > 0 (Anti-Parallel) Higher surrounding a nuclei perturb the local magnetic field: Beff(r) = B0(1-(r)), where (r) depends on localNMR-0Fessler, Univ. of Michigan Nuclear Magnetic Resonance Imaging Jeffrey A. Fessler EECS

Fessler, Jeffrey A.

377

TWO-DIMENSIONAL NMR SIGNAL ANALYSIS WITH AN ADAPTED SUBBAND  

E-print Network

: This paper presents a methodology allowing to estimate the parameters of two-dimensional damped frequency estimator based on the Prony model. At each node resulting from the decomposition, a stopping rule. [2002]). In this paper, we consider the problem of estimat- ing the parameters of two-dimensional NMR

Boyer, Edmond

378

A boxcar integrator for pulsed NMR relaxation time measurements  

Microsoft Academic Search

A two-channel analogue boxcar integrator is constructed by using integrated circuits and MOST gates. A ratio of two NMR fee-induction signals can be measured and thus the spin-lattice relaxation time T1 can be obtained without any calculation by comparing output voltages of the channels by the null method.

L. Niemela

1972-01-01

379

Protein Dielectric Constants Determined from NMR Chemical Shift Perturbations  

E-print Network

Protein Dielectric Constants Determined from NMR Chemical Shift Perturbations Predrag Kukic limited by a long-standing discussion on which value to use for the dielectric constants (eff and p CSPs optimally with a protein dielectric constant (eff) from 3 to 13, with an optimal value across all

McIntosh, Lawrence P.

380

COMMUNICATION A NMR experiment for simultaneous correlations of valine  

E-print Network

Science+Business Media Dordrecht (outside the USA) 2013 Abstract A methyl-detected `out-and-back' NMR-molecular- weight proteins (Gelis et al. 2007; Hamel and Dahlquist 2005; Religa et al. 2010; Rosenzweig et al. 2013 and provide significant sensitivity gains in methyl resonance assignment experiments (Tugarinov and Kay 2003

Clore, G. Marius

381

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

382

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

383

The new ?-NMR facility at TRIUMF and applications in semiconductors  

NASA Astrophysics Data System (ADS)

A new facililty for conducting beta-detected nuclear magnetic resonance (?-NMR) investigations of condensed matter systems has recently been constucted at TriUniversity Meson Facility in Vancouver, Canada. The unique features of this new facility are described, and some preliminary results on 8Li+ in GaAs are presented.

Chow, K. H.; Salman, Z.; Kiefl, R. F.; MacFarlane, W. A.; Levy, C. D. P.; Amaudruz, P.; Baartman, R.; Chakhalian, J.; Daviel, S.; Hirayama, Y.; Hatakeyama, A.; Arseneau, D. J.; Hitti, B.; Kreitzman, S. R.; Morris, G. D.; Poutissou, R.; Reynard, E.

2003-12-01

384

Low field NMR in aerogel-confined superfluid ^3He  

NASA Astrophysics Data System (ADS)

The superfluid states of bulk liquid ^3He were convincingly identified through their longitudinal and transverse NMR spectra. The order parameters of the superfluid phases of ^3He confined within aerogel have generally been assumed to be identical to those in bulk liquid. While that identification has not been contradicted by experimental data, it has not yet been tested as carefully as in bulk. Fomin has suggested that the A-like phase in aerogel could be an axiplanar state, distinct from the bulk axial state. We have tested the identification by studying low-field NMR which is more sensitive to the distinction between the candidate states. Using the dc SQUID based NMR detection system developed in our laboratory over many years we have studied both longitudinal and transverse resonance spectra in 99.5% porosity aerogel in magnetic fields of 1-4 mT, an order of magnitude lower than previous NMR work. Our work shows qualitative features similar to those found in higher magnetic fields. While we were unable to resolve the longitudinal resonance, transverse resonance measurements exhibit a characteristic field- and temperature-dependence.

Du, Yuliang; Bozler, H. M.; Gould, C. M.

2008-03-01

385

A 31P-NMR study of borophosphate glasses  

Microsoft Academic Search

It is shown that 31P nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) discriminates among different types of PO4 units occurring in borophosphate glasses. The isotropic 31P chemical shift of the PO4 increases by nearly 70 ppm in going from the ``branching unit,'' neutral and covalently bonded, to the ``monomeric unit,'' which carries a -3 nominal charge. By

Marco Villa; Keith R. Carduner; Gaetano Chiodelli

1987-01-01

386

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

387

Accepted Manuscript H-NMR metabonomics can differentiate the early  

E-print Network

metabolic changes linked to atherogenesis were measured using plasma 1 H-NMR-based8 metabonomics. The lowest atherogenicity was obtained with the plant-oil cheese diet,9 followed by the dairy fat cheese diet, while: 0.45-0.51) were the most positively correlated metabolites, whereas a15 multimetabolite response

Boyer, Edmond

388

ECG gated NMR-CT for cardiovascular diseases  

SciTech Connect

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

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

1985-05-01

389

NMR in rotating magnetic fields: Magic angle field spinning  

SciTech Connect

Magic angle sample spinning has been one of the cornerstones in high-resolution solid state NMR. Spinning frequencies nowadays have increased by at least one order of magnitude over the ones used in the first experiments and the technique has gained tremendous popularity. It is currently a routine procedure in solid-state NMR, high-resolution liquid-state NMR and solid-state MRI. The technique enhances the spectral resolution by averaging away rank 2 anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. Andrew proposed that it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B0 field (B0-MAS) and this has been recently demonstrated using electromagnetic field rotation. Here we discuss on the possibilities to perform field rotation using alternative hardware, together with spectroscopic methods to recover isotropic resolution even in cases where the field is not rotating at the magic angle. Extension to higher magnetic fields would be beneficial in situations where the physical manipulation of the sample is inconvenient or impossible. Such situations occur often in materials or biomedical samples where ''ex-situ'' NMR spectroscopy and imaging analysis is needed.

Sakellariou, D.; Meriles, C.; Martin, R.; Pines, A.

2004-09-10

390

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

391

Journal of Biomolecular NMR, 21: 6768, 2001. KLUWER/ESCOM  

E-print Network

Department of Chemistry, cThe Biotechnology Laboratory, and the a,bProtein Engineering Network of Centres of Excellence to syn- thesize nitroxide spin-labeled cello-oligosaccharides for paramagnetic relaxation measurements-NMR spectrum of cellopentaose is highly degenerate. With the excep- tion of the -anomeric H1 from the reducing

McIntosh, Lawrence P.

392

Plastic NMR Tubes and Reactor Systems for Handling Fluorine Compounds  

Microsoft Academic Search

A PLAST~C sample tube, which possesses adequate magnetlc transparency, has been develotJed and used extensively in these laboratories for !9F NMR analysis of corrosive fluorine compounds not requiring spinning. The plastic material found most suitable is translucent poly­ trifluorochloroethylene, preferably a modified type such as Allied Chemical \\

Christian A. Wamser; Burch B. Stewart

1965-01-01

393

Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies  

SciTech Connect

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

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

1999-05-05

394

Communications: Nanomagnetic shielding: High-resolution NMR in carbon allotropes  

E-print Network

Communications: Nanomagnetic shielding: High-resolution NMR in carbon allotropes Y. Kim,1,a E. Abou report the largest diamagnetic shifts down to 68.3 ppm ever observed in carbon allotropes, which of the magnetic properties of carbon-based materials is of fundamental relevance in applications in nano

Zettl, Alex

395

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

396

A study of petroleum alkylcarbazoles using 1H NMR spectroscopy  

Microsoft Academic Search

A precision method for measuring proton chemical shift calculations of methylcarbazoles has been developed. For other abundant substituents the proton chemical shift correlation diagrams are reported. The method makes it possible to identify a number of carbazole structures present in petroleums. General structural regularities of petroleum carbazoles have been defined from 1H NMR data. Methylcarbazole isomers with 1- and 1,8-substituents

M. B. Smirnov; E. B. Frolov

1997-01-01

397

Quantum Information Processing with NMR MIT Department of Physics  

E-print Network

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

Seager, Sara

398

On-line system for NMR polarization measurement  

Microsoft Academic Search

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

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

1995-01-01

399

Scalable NMR spectroscopy with semiconductor chips Dongwan Haa  

E-print Network

-Qiao Songb , and Donhee Hama,1 a School of Engineering and Applied Sciences, Harvard University, Cambridge magnets, whose high and uniform magnetic fields lead to the fine spectral resolution necessary make the benefits of NMR spectroscopy more broadly available and en- able new applications. Bulky

Ham, Donhee

400

Original article NMR relaxometry as a non-invasive tool  

E-print Network

for the quality of many food powders. The NMR method developed gives a complete picture of the reconstitution micelles concentrated by tangential microfiltration and powdered by spray-drying can be significantly improved by addition of whey pro- teins, suitable polydextroses or NaCl before spray-drying powder, without

Paris-Sud XI, Université de

401

Flexibility of ZIF-8 materials studied using 129Xe NMR.  

PubMed

Structural changes in a porous hybrid inorganic-organic ZIF-8 compound have been explored using hyperpolarized (129)Xe NMR of adsorbed xenon at various temperatures. Upon xenon adsorption at low temperature, the organic linkers undergo a reorientation leading to a stepwise increase in xenon adsorption and in chemical shift. PMID:23862180

Springuel-Huet, Marie-Anne; Nossov, Andrei; Guenneau, Flavien; Gédéon, Antoine

2013-08-28

402

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24771455

Jokisaari, Jukka; Zhu, Jianfeng

2014-10-01

403

NMR studies of bond arrangements in alkali phosphate glasses  

SciTech Connect

Solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has become a powerful tool for the investigation of local structure and medium range order in glasses. Previous {sup 31}P MAS NMR studies have detailed the local structure for a series of phosphate glasses. Phosphate tetrahedra within the glass network are commonly described using the Q{sup n} notation, where n = 0, 1, 2, 3 and represents the number of bridging oxygens attached to the phosphate. Using {sup 31}P MAS NMR different phosphate environments are readily identified and quantified. In this paper, the authors present a brief description of recent one dimensional (1D) {sup 6}Li, {sup 7}Li and {sup 31}P MAS experiments along with two-dimensional (2D) {sup 31}P exchange NMR experiments for a series of lithium ultraphosphate glasses. From the 2D exchange experiments the connectivities between different Q{sup n} phosphate tetrahedra were directly measured, while the 1D experiments provided a measure of the P-O-P bond angle distribution and lithium coordination number as a function of Li{sub 2}O concentration.

Alam, T.M.; Brow, R.K.

1998-01-01

404

Contaminations of herbal products determined by NMR fingerprint  

Microsoft Academic Search

The utilisation of NMR fingerprinting is proposed as a rapid, available and reliable method to determine the contamination of herbal products. The presence of nimesulide has been reported recently as the contaminant of P.C. 28 Plus, a product based on herbal drugs marketed by the Italian company Cosval. The presence of the substance, as well as its relevant concentration (5%),

Marcello Nicoletti; Valentina Petitto

2010-01-01

405

NMR structures of membrane proteins in phospholipid bilayers.  

PubMed

Membrane proteins have always presented technical challenges for structural studies because of their requirement for a lipid environment. Multiple approaches exist including X-ray crystallography and electron microscopy that can give significant insights into their structure and function. However, nuclear magnetic resonance (NMR) is unique in that it offers the possibility of determining the structures of unmodified membrane proteins in their native environment of phospholipid bilayers under physiological conditions. Furthermore, NMR enables the characterization of the structure and dynamics of backbone and side chain sites of the proteins alone and in complexes with both small molecules and other biopolymers. The learning curve has been steep for the field as most initial studies were performed under non-native environments using modified proteins until ultimately progress in both techniques and instrumentation led to the possibility of examining unmodified membrane proteins in phospholipid bilayers under physiological conditions. This review aims to provide an overview of the development and application of NMR to membrane proteins. It highlights some of the most significant structural milestones that have been reached by NMR spectroscopy of membrane proteins, especially those accomplished with the proteins in phospholipid bilayer environments where they function. PMID:25032938

Radoicic, Jasmina; Lu, George J; Opella, Stanley J

2014-08-01

406

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

407

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

408

Theoretical studies on structures, 13 C NMR chemical shifts, aromaticity,  

E-print Network

of capping hydrogen atoms at the open ends of a SWCNT changes the chemical activity of the SWCNTTheoretical studies on structures, 13 C NMR chemical shifts, aromaticity, and chemical reactivity The geometries, chemical shifts, aromaticity, and reactivity of finite-length open-ended armchair single- walled

Wang, Yan Alexander

409

PFG NMR investigations of TPA-TMA-silica mixtures.  

PubMed

Pulsed-field gradient (PFG) NMR studies of tetrapropylammonium (TPA)-tetramethylammonium (TMA)-silica mixtures are presented, and the effect of TMA as a foreign ion on the TPA-silica nanoparticle interactions before and after heating has been studied. Dynamic light scattering (DLS) results suggest that silica nanoparticles in these TPA-TMA systems grow via a ripening mechanism for the first 24 h of heating. PFG NMR of mixtures before heating show that TMA can effectively displace TPA from the nanoparticle surface. The binding isotherms of TPA at room temperature obtained via PFG NMR can be described by Langmuir isotherms, and indicate a decrease in the adsorbed amount of TPA upon addition of TMA. PFG NMR also shows a systematic increase in the self-diffusion coefficient of TPA in both the mixed TPA-TMA systems and pure TPA systems with heating time, indicating an increased amount of TPA in solution upon heating. By contrast, a much smaller amount of TMA is observed to desorb from the nanoparticles upon heating. These results point to the desorption of TPA from the nanoparticles being a kinetically controlled process. The apparent desorption rate constants were calculated from fitting the desorbed amount of TPA with time via a pseudosecond-order kinetic model. This analysis show the rate of TPA desorption in TPA-TMA mixtures increases with increasing TMA content, whereas for pure TPA mixtures the rate of TPA desorption is much less sensitive to the TPA concentration. PMID:21395275

Li, Xiang; Shantz, Daniel F

2011-04-01

410

Journal of Biomolecular NMR, 16: 313327, 2000. KLUWER/ESCOM  

E-print Network

state NMR REDOR measurements John J. Balbacha, Jun Yangb, David P. Welikyb, Peter J. Steinbachc, Vitali; Bazan et al., 1998; Dragic et al., 1998; Rizzuto et al., 1998; Berger et al., 1999). The third that a particular strain of HIV-1 can infect (Shioda et al., 1992; Cocchi et al., 1996; Berger et al., 1999) through

Weliky, David

411

Investigation of NMR limits of detection for implantable microcoils  

Microsoft Academic Search

Although NMR has the ability to investigate biological systems non-destructively, its low sensitivity primarily has hampered their investigation compared to other analytical techniques. Therefore, optimizing radio frequency (RF) coils to improve sensitivity do offer benefits in MR spectroscopy (MRS). Sensitivity may be improved for mass- and volume- limited samples if the size of the detection RF coils matches the sample

N. Baxan; A. Rengle; G. Pasquet; J.-F. Chateaux; A. Briguet; P. Morin; L. Fakri-Bouchet

2007-01-01

412

NMR spectroscopy and perfusion of mammalian cells using surface microprobes.  

PubMed

NMR spectra of mammalian cells are taken using surface microprobes that are based on microfabricated planar coils. The surface microprobe resembles a miniaturized Petri dish commonly used in biological research. The diameter of the planar coils is 1 mm. Chinese Hamster Ovaries are immobilized in a uniform layer on the microprobe surface or patterned by an ink-jet printer in the centre of the microcoil, where the rf-field of the planar microcoil is most uniform. The acquired NMR spectra show the prevalent metabolites found in mammalian cells. The volumes of the detected samples range from 25 nL to 1 nL (or 50,000 to 1800 cells). With an extended set-up that provides fluid inlets and outlets to the microprobe, the cells can be perfused within the NMR-magnet while constantly taking NMR spectra. Perfusion of the cells opens the way to increased cell viability for long acquisitions or to analysis of the cells' response to environmental change. PMID:17330170

Ehrmann, Klaus; Pataky, Kristopher; Stettler, Matthieu; Wurm, Florian Maria; Brugger, Jürgen; Besse, Pierre-André; Popovic, Radivoje

2007-03-01

413

Microslot NMR Probe for Metabolomics Studies Hans Georg Krojanski,  

E-print Network

by practical problems. Therefore, planar microcoils, which are easier to scale down, were tested. Additionally microcoils were used for high- resolution 1 H NMR, which are based on planar, electromagnetic waveguides can be obtained with this probe in a few seconds. The planar geometry of the probe is easily adaptable

Suter, Dieter

414

Solid-state NMR spectroscopy of Pb-rich apatite.  

PubMed

Pb-containing hydroxylapatite phases synthesized under aqueous conditions were investigated by X-ray diffraction and solid-state nuclear magnetic resonance (NMR) techniques to determine the Pb, Ca distribution. 31P and 1H magic-angle spinning (MAS) NMR results indicate slight shifts of the isotropic chemical shift with increased Ca content and complex lineshapes at compositions with near equal amounts of Ca and Pb. 31P{207Pb} and 1H{207Pb} rotational-echo double resonance (REDOR) results for intermediate compositions show that resolved spectral features cannot be assigned simply in terms of local Ca, Pb configurations or coexisting phases. 207Pb MAS NMR spectra are easily obtained for these materials and contain well-resolved resonances for crystallographically unique A1 and A2 Pb sites. Splitting of the A1 and A2 207Pb resonances for pure hydroxyl-pyromorphite (Pb10(PO4)6(OH)2) compared to natural pyromorphite (Pb5(PO4)3Cl) suggests symmetry reduced from hexagonal. We find that 207Pb{1H} CP/MAS NMR is impractical in Pb-rich hydroxylapatites due to fast 207Pb relaxation. PMID:19821466

Mason, Harris E; Hirner, Joshua J; Xu, Wenqian; Parise, John B; Phillips, Brian L

2009-12-01

415

Structure\\/function studies of anticoagulant sulphated polysaccharides using NMR  

Microsoft Academic Search

Sulphated polysaccharides have many biological functions, which depend on binding of highly specific carbohydrate structures to proteins. NMR spectroscopy is a technique capable of detailed structural elucidation of these polysaccharides, and can be used in applications ranging from routine analysis to research into covalent and conformational aspects of polysaccharide structure. This technique can be used to characterise sequence variations in

B. Mulloy; P. A. S. Mourao; E. Gray

2000-01-01

416

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

417

Field Experiment Provides Ground Truth for Surface NMR Measurement  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

418

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

419

Recent progress in NMR/MRI in petroleum applications  

NASA Astrophysics Data System (ADS)

NMR has become an important technique for characterization of porous materials. In particular, its importance in petroleum exploration has been enhanced by the recent progress in NMR well-logging techniques and instruments. Such advanced techniques are increasing being accepted as a valuable service especially in deep-sea exploration. This paper will outline the recent progress of MR techniques at Schlumberger-Doll Research. Well-logging - The second generation NMR well-logging tool and the 2D NMR methods (D-T2, etc) enable measurements at several depths from the well bore allowing a one-dimensional profiling of the fluid. Such data have allowed quantification of fluid invasion during drilling, obtaining the properties of native fluids and identifying oil/gas zones. MRI- Rocks from oil reservoirs are heterogeneous (e.g. large range of pore sizes and porosity variation) due to the complex geological and geochemical histories. The spatial pattern of the heterogeneity has not been well studied. We have developed several NMR techniques to quantify pore length scale previously. In order to predict flow over a large length scale, it is necessary to determine spatial heterogeneity and pore connectivity over the relevant size. We have performed MRI on a series of carbonate rocks and found interesting patterns of the heterogeneity characteristics. Mathematics - It is well known that the Laplace inversion is non-unique and the resulting spectrum can be strongly dependent on the prior constraints, specific algorithm and noise. However, the different spectra can all be solutions consistent with data. It would be useful to have a robust criterion -- independent of algorithms -- to determine the properties of the resulting spectrum. Several methods will be described to examine the statistics of the solutions, uncertainty of the spectrum and its integrals and resolution.

Song, Yi-Qiao

2007-03-01

420

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

421

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

Microsoft Academic Search

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

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

2006-01-01

422

Solid-state NMR characterization of the acid sites in cubic mesoporous Al-MCM-48 materials using trimethylphosphine oxide as a 31P NMR probe  

Microsoft Academic Search

The acidic properties of Al-MCM-48 with Si\\/Al ratios ranging from 10 to 67, synthesized with Gemini surfactant as the template, have been characterized by a combination of multinuclear solid-state 1H, 23Na, 27Al, 29Si and 31P MAS (magic angle spinning) NMR and some double-resonance NMR methods using trimethylphosphine oxide (TMPO) as a probe molecule. XRD and 27Al MAS NMR results indicated

Hsien-Ming Kao; Pai-Ching Chang; Yun-Wen Liao; Lung-Ping Lee; Chu-Hua Chien

2008-01-01

423

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, December 15, 1988-March 15, 1989.  

National Technical Information Service (NTIS)

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 g...

K. W. Zilm

1989-01-01

424

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

425

Could smaller really be better? Current and future trends in high-resolution microcoil NMR spectroscopy.  

PubMed

NMR is an invaluable analytical technique that provides structural and chemical information about a molecule without destroying the sample. However, NMR suffers from an inherent lack of sensitivity compared to other popular analytical techniques. This trends article focuses on strategies to increase the sensitivity of NMR using solenoidal microcoil, microstrip, and microslot probes. The role of these reduced-volume receiver coils for detection in hyphenated capillary electrophoresis (CE) and capillary isotachophoresis (cITP) NMR experiments is discussed. Future directions will likely build on work to develop probes containing multiple coils for high-throughput NMR and field-portable instruments. PMID:21879299

Jones, Christopher J; Larive, Cynthia K

2012-01-01

426

PR-CALC: A Program for the Reconstruction of NMR Spectra from Projections  

Microsoft Academic Search

Projection-reconstruction NMR (PR-NMR) has attracted growing attention as a method for collecting multidimensional NMR data\\u000a rapidly. The PR-NMR procedure involves measuring lower-dimensional projections of a higher-dimensional spectrum, which are\\u000a then used for the mathematical reconstruction of the full spectrum. We describe here the program PR-CALC, for the reconstruction\\u000a of NMR spectra from projection data. This program implements a number of

Brian E. Coggins; Pei Zhou

2006-01-01

427

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

428

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

429

Microscale simulations of NMR relaxation in porous media  

NASA Astrophysics Data System (ADS)

In petrophysical applications of nuclear magnetic resonance (NMR), the measured relaxation signals originate from the fluid filled pore space. Hence, in rocks or sediments the water content directly corresponds to the initial amplitude of the recorded NMR relaxation signals. The relaxation rate (longitudinal/transversal decay time T1, T2) is sensitive to pore sizes and physiochemical properties of rock-fluid interfaces (surface relaxivity), as well as the concentration of paramagnetic ions in the fluid phases (bulk relaxivity). In the subproject A2 of the TR32 we aim at improving the basic understanding of these processes at the pore scale and thereby advancing the interpretation of NMR data by reducing the application of restrictive approximated interpretation schemes, e.g. for deriving pore size distributions, connectivity or permeability. In this respect we numerically simulate NMR relaxation data at the micro sale to study the impact of physical and hydrological parameters such as internal field gradients or pore connectivities on NMR signals. Joint numerical simulations of the NMR relaxation behavior (Bloch equations) in the presence of internal gradients (Ampere's law) and fluid flow (Navier-Stokes) on a pore scale dimension have been implemented in a finite element (FE) model using Comsol Multiphysics. Processes governing the time and spatial behavior of the nuclear magnetization density in a porous medium are diffusion and surface interactions at the rock-fluid interface. Based on Fick's law of diffusive motion Brownstein and Tarr (1979) introduced differential equations that describe the relaxation behavior of the Spin magnetization in single isolated pores and derived analytical solutions for simple geometries, i.e. spherical, cylindrical and planar. However, by numerically solving these equations in a general way using a FE algorithm this approach can be applied to study and simulate coupled complex pore systems, e.g. derived from computer tomography (CT). In this respect substantial coupling effects in typical porous rocks can be observed at pore sizes about <1 ?m, e.g. encountered in tight gas reservoir formations. Internal magnetic field gradients in rocks arise due to susceptibility contrasts in pore fluid and rock matrix and depend on the magnetic field strength (Larmor frequency). To model the increased relaxation rate observed in CPMG measurements due to diffusive motion in a magnetic (internal) gradient field the simulations are coupled with calculations of spatial distribution of field gradients within the simulated fluid-matrix system according to Ampere's law. Contrary to common assumptions of a constant ratio between T1 and T2 in petrophysical NMR the CPMG simulations in the presence of internal gradients show a significant increase of T1/T2 ratios with decreasing pore sizes. This implies a shift of derived signal contributions to smaller pore sizes, e.g. <1 ?m, from T2 NMR experiments, and thus an underestimation of derived permeabilities. ?m These simulations will also be compiled for multi-phase systems, e.g. water-air-oil, to study basic correlations between NMR and hydrological parameters of partially saturated rocks. This study was conducted within the framework of the Transregional Collaborative Research Centre 32, funded by the German Research Foundation (DFG).

Mohnke, Oliver; Klitzsch, Norbert

2010-05-01

430

Microscale simulations of NMR relaxation in porous media  

NASA Astrophysics Data System (ADS)

In petrophysical applications of nuclear magnetic resonance (NMR), the measured relaxation signals originate from the fluid filled pore space. Hence, in rocks or sediments the water content directly corresponds to the initial amplitude of the recorded NMR relaxation signals. The relaxation rate (longitudinal/transversal decay time T1, T2) is sensitive to pore sizes and physiochemical properties of rock-fluid interfaces (surface relaxivity), as well as the concentration of paramagnetic ions in the fluid phases (bulk relaxivity). We aim at improving the basic understanding of these processes at the pore scale and thereby advancing the interpretation of NMR data by reducing the application of restrictive approximated interpretation schemes, e.g. for deriving pore size distributions, connectivity or permeability. In this respect we numerically simulate NMR relaxation data at the micro sale to study the impact of physical and hydrological parameters such as internal field gradients or pore connectivities on NMR signals. Joint numerical simulations of the NMR relaxation behavior (Bloch equations) in the presence of internal gradients (Ampere’s law) and fluid flow (Navier-Stokes) on a pore scale dimension have been implemented in a finite element (FE) model using Comsol Multiphysics. Processes governing the time and spatial behavior of the nuclear magnetization density in a porous medium are diffusion and surface interactions at the rock-fluid interface. Based on Fick's law of diffusive motion Brownstein and Tarr (1979) introduced differential equations that describe the relaxation behavior of the Spin magnetization in single isolated pores and derived analytical solutions for simple geometries, i.e. spherical, cylindrical and planar. However, by numerically solving these equations in a general way using a FE algorithm this approach can be applied to study and simulate coupled complex pore systems, e.g. derived from computer tomography (CT). In this respect substantial coupling effects in typical porous rocks can be observed at pore sizes about <1 ?m, e.g. encountered in tight gas reservoir formations. Internal magnetic field gradients in rocks arise due to susceptibility contrasts in pore fluid and rock matrix and depend on the magnetic field strength (Larmor frequency). To model the increased relaxation rate observed in CPMG measurements due to diffusive motion in a magnetic (internal) gradient field the simulations are coupled with calculations of spatial distribution of field gradients within the simulated fluid-matrix system according to Ampere's law. Contrary to common assumptions of a constant ratio between T1 and T2 in petrophysical NMR the CPMG simulations in the presence of internal gradients show a significant increase of T1/T2 ratios with decreasing pore sizes. This implies a shift of derived signal contributions to smaller pore sizes, e.g. <1 ?m, from T2 NMR experiments, and thus an underestimation of derived permeabilities. ?m These simulations will also be compiled for multi-phase systems, e.g. water-air-oil, to study basic correlations between NMR and hydrological parameters of partially saturated rocks. This study was conducted within the framework of the Transregional Collaborative Research Centre 32, funded by the German Research Foundation (DFG).

Mohnke, O.; Klitzsch, N.; Clauser, C.

2009-12-01

431

NMR detection with multiple solenoidal microcoils for continuous-flow capillary electrophoresis.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy represents a promising on-line detector for capillary electrophoresis (CE). The inherent poor sensitivity of NMR mandates the use of NMR probes with the highest mass sensitivity, such as those containing solenoidal microcoils, for CE/NMR hyphenation. However, electrophoretic current degrades the resolution of NMR spectra obtained from solenoidal coils. A new method to avoid microcoil NMR spectral degradation during continuous-flow CE is demonstrated using a unique multiple solenoidal coil NMR probe. The electrophoretic flow from a single separation capillary is split into multiple outlets, each possessing its own NMR detection coil. While the CE electrophoretic flow is directed through one outlet, stopped-flow, high-resolution NMR spectra are obtained from the coil at the other outlet. The electrophoretic flow and NMR measurements are cycled between the outlets to allow a continuous CE separation with "stopped-flow" detection. As a new approach for improving multiple coil probe performance, the magnetic field homogeneity is automatically adjusted (via the shim coils of the magnet) for the active coil. The multiple microcoil CE/NMR coupling has been used to analyze a <3 nmole mixture of amines while obtaining between 1 and 2 Hz line width, demonstrating the ability to avoid electrophoretic current-induced line broadening. PMID:12433087

Wolters, Andrew M; Jayawickrama, Dimuthu A; Webb, Andrew G; Sweedler, Jonathan V

2002-11-01

432

UltraSOFAST HMQC NMR and the Repetitive Acquisition of 2D Protein Spectra at Hz Rates  

E-print Network

UltraSOFAST HMQC NMR and the Repetitive Acquisition of 2D Protein Spectra at Hz Rates Maayan Gal of different approaches enabling the rapid acquisition of 2D NMR spectra have been recently introduced, including spatially encoded "ultrafast" 2D NMR spectroscopy and SOFAST HMQC NMR. Whereas the former

Frydman, Lucio

433

Reference Deconvolution, Phase Correction, and Line Listing of NMR Spectra by the 1D Filter Diagonalization Method  

E-print Network

to the case of model multidimensional time signals (4) and large 2D NMR data sets (5). The object of 1D FDMReference Deconvolution, Phase Correction, and Line Listing of NMR Spectra by the 1D Filter to attack the problem of identifying and quantifying the number of NMR transitions in a given NMR spectrum

Mandelshtam, Vladimir A.

434

Modeling rock permeability from NMR relaxation data by PLS regression  

NASA Astrophysics Data System (ADS)

This study explores the application of the partial least squares regression (PLSR) technique to rock permeability prediction from nuclear magnetic resonance (NMR) relaxation data. A total of 68 Brazilian sandstone cores selected from reservoirs and outcrop analogs were fully saturated and analyzed by NMR. The permeability of the cores ranged from 0.007 to 9,800 mD. From their 1H transverse relaxation times ( T2) measured at 2 MHz, two PLSR models were developed for the relaxation spectra and the raw relaxation curves. Both models led to more uniform and accurate predictions (RMSE = 0.47 and 0.50 log mD, respectively) compared with the classical Kenyon model (RMSE = 0.78 log mD).

Rios, Edmilson Helton; Ramos, Paulo Frederico de Oliveira; Machado, Vinicius de França; Stael, Giovanni Chaves; Azeredo, Rodrigo Bagueira de Vasconcellos

2011-12-01

435

Diffusion exchange NMR spectroscopy in inhomogeneous magnetic fields  

NASA Astrophysics Data System (ADS)

Two-dimensional diffusion exchange experiments in the presence of a strong, static magnetic field gradient are presented. The experiments are performed in the stray field of a single sided NMR sensor with a proton Larmor frequency of 11.7 MHz. As a consequence of the strong and static magnetic field gradient the magnetization has contributions from different coherence pathways. In order to select the desired coherence pathways, a suitable phase cycling scheme is introduced. The pulse sequence is applied to study diffusion as well as the molecular exchange properties of organic solvents embedded in a mesoporous matrix consisting of a sieve of zeolites with a pore size of 0.8 nm and grain size of 2 ?m. This pulse sequence extends the possibilities of the study of transport properties in porous media, with satisfying sensitivity in measurement times of a few hours, in a new generation of relatively inexpensive low-field NMR mobile devices.

Neudert, Oliver; Stapf, Siegfried; Mattea, Carlos

2011-02-01

436

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

437

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

438

Structural analysis of teicoplanin A2 by 2d NMR  

NASA Astrophysics Data System (ADS)

The analysis of the intact glycopeptide antibiotic, teicoplanin A 2, by two-dimensional proton NMR is described. Delayed-correlation spectroscopy (COSY), double-quantum coherence experiments (DACE), and nuclear Overhauser spectroscopy (NOESY) are utilized to confirm the primary structure. Distance constraints derived from NOESY data integrated with computer-assisted molecular modeling and force-field energy minimization yields a proposed three-dimensional solution-state conformation. Included are NMR methods developed for improved accuracy of distance measurements from 2D NOE experiments obtained on samples dissolved in DMSO- d6/water. The effects of different pulse sequences for water suppression on the 2D NOE spectral results are compared. Clear indication that teicoplanin exists in two unequally populated conformations which are in slow exchange is revealed by the presence of cross peaks attributable to conformational interchange in the NOESY spectra.

Heald, Sarah L.; Mueller, Luciano; Jeffs, Peter W.

439

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

440

Characterizing RNA ensembles from NMR data with kinematic models  

PubMed Central

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

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

2014-01-01

441

Fast protein backbone NMR resonance assignment using the BATCH strategy.  

PubMed

Probing protein structure, dynamics, and interaction surfaces by NMR requires initial backbone resonance assignment. The protocol for this step has been progressively developed in the last 15 years to provide robust assignments. However, even in the case of favorable conditions (high field magnets and cryogenically cooled probes, small globular proteins, high sample concentration), the assignment step generally takes several days of data collection and analysis, thus precluding studies of unstable proteins and limiting high-throughput applications. Recently, we have introduced the BATCH strategy for fast protein backbone resonance assignment. BATCH benefits from the combination of several tools (BEST/ASCOM/Targeted-Sampling/COBRA/HADAMAC) for time-optimized and highly automated NMR data acquisition, processing, and analysis. In this chapter, we discuss the individual steps of the BATCH method and describe its practical implementation to obtain the backbone resonance assignment of small globular proteins in a few hours of time. PMID:22167685

Brutscher, Bernhard; Lescop, Ewen

2012-01-01

442

NMR shifts for polycyclic aromatic hydrocarbons from first-principles  

SciTech Connect

We present first-principles, density-functional theory calculations of the NMR chemical shifts for polycyclic aromatic hydrocarbons, starting with benzene and increasing sizes up to the one- and two-dimensional infinite limits of graphene ribbons and sheets. Our calculations are performed using a combination of the recently developed theory of orbital magnetization in solids, and a novel approach to NMR calculations where chemical shifts are obtained from the derivative of the orbital magnetization with respect to a microscopic, localized magnetic dipole. Using these methods we study on equal footing the 1H and 13C shifts in benzene, pyrene, coronene, in naphthalene, anthracene, naphthacene, and pentacene, and finally in graphene, graphite, and an infinite graphene ribbon. Our results show very good agreement with experiments and allow us to characterize the trends for the chemical shifts as a function of system size.

Thonhauser, Timo; Ceresoli, Davide; Marzari, Nicola N.

2009-09-03

443

A Xe-129 NMR Study of Functionalized Ordered Mesoporous Silica  

SciTech Connect

In this publication we report the first application of continuous flow hyperpolarized (HP) 129Xe techniques to studies of pore structure in ordered mesoporous materials. In particular, we report extensive 129Xe NMR chemical shift and spin-lattice relaxation time measurements of xenon adsorbed in mesoporous materials of different porosities and surface chemical composition. The use of HP Xe has allowed us to work at very low concentrations of xenon where the contribution of the Xe-Xe interactions is negligible and the observed 129Xe chemical shift reflects mainly interactions between the xenon atoms and the surface. Variable temperature measurements gave access to information on the adsorption parameters of xenon, and allowed us to follow the changes in these properties due to modification of the mesopore voids. Our 129Xe NMR data reveal a non-uniform porosity and irregular pore structure in contrast to N2 adsorption and TEM measurements that indicate regular nanoporous channels.

Moudrakovski, Igor L. (Steacie Institute for Molecular Sciences); Terskikh, V. V. (Steacie Institute for Molecular Sciences, National Research Council); Ratcliffe, C I. (Steacie Institute for Molecular Sciences, National Research Council); Ripmeester, J A. (Steacie Institute for Molecular Sciences, National Research Council); Wang, Li-Qiong (BATTELLE (PACIFIC NW LAB)); Shin, Yongsoon (BATTELLE (PACIFIC NW LAB)); Exarhos, Gregory J. (BATTELLE (PACIFIC NW LAB))

2001-12-01

444

Heterogeneous solution NMR signal amplification by reversible exchange.  

PubMed

A novel variant of an iridium-based organometallic catalyst was synthesized and used to enhance the NMR signals of pyridine in a heterogeneous phase by immobilization on polymer microbead solid supports. Upon administration of parahydrogen (pH2) gas to a methanol mixture containing the HET-SABRE catalyst particles and the pyridine, up to fivefold enhancements were observed in the (1)H?NMR spectra after sample transfer to high field (9.4?T). Importantly, enhancements were not due to any residual catalyst molecules in solution, thus supporting the true heterogeneity of the SABRE process. Further significant improvements may be expected by systematic optimization of experimental parameters. Moreover, the heterogeneous catalyst is easy to separate and recycle, thus opening a door to future potential applications varying from spectroscopic studies of catalysis, to imaging metabolites in the body without concern of contamination from expensive and potentially toxic metal catalysts or accompanying organic molecules. PMID:24889730

Shi, Fan; Coffey, Aaron M; Waddell, Kevin W; Chekmenev, Eduard Y; Goodson, Boyd M

2014-07-14

445

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

446

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

447

Accelerating multidimensional NMR and MRI experiments using iterated maps  

NASA Astrophysics Data System (ADS)

Techniques that accelerate data acquisition without sacrificing the advantages of fast Fourier transform (FFT) reconstruction could benefit a wide variety of magnetic resonance experiments. Here we discuss an approach for reconstructing multidimensional nuclear magnetic resonance (NMR) spectra and MR images from sparsely-sampled time domain data, by way of iterated maps. This method exploits the computational speed of the FFT algorithm and is done in a deterministic way, by reformulating any a priori knowledge or constraints into projections, and then iterating. In this paper we explain the motivation behind this approach, the formulation of the specific projections, the benefits of using a ‘QUasi-Even Sampling, plus jiTter' (QUEST) sampling schedule, and various methods for handling noise. Applying the iterated maps method to real 2D NMR and 3D MRI of solids data, we show that it is flexible and robust enough to handle large data sets with significant noise and artifacts.

Frey, Merideth A.; Sethna, Zachary M.; Manley, Gregory A.; Sengupta, Suvrajit; Zilm, Kurt W.; Loria, J. Patrick; Barrett, Sean E.

2013-12-01

448

Susceptibility-matched plugs for microcoil NMR probes  

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

449

Operating nanoliter scale NMR microcoils in a 1 tesla field  

NASA Astrophysics Data System (ADS)

Microcoil probes enclosing sample volumes of 1.2, 3.3, 7.0, and 81 nanoliters are constructed as nuclear magnetic resonance (NMR) detectors for operation in a 1 tesla permanent magnet. The probes for the three smallest volumes utilize a novel auxiliary tuning inductor for which the design criteria are given. The signal-to-noise ratio (SNR) and line width of water samples are measured. Based on the measured DC resistance of the microcoils, together with the calculated radio frequency (RF) resistance of the tuning inductor, the SNR is calculated and shown to agree with the measured values. The details of the calculations indicate that the auxiliary inductor does not degrade the NMR probe performance. The diameter of the wire used to construct the microcoils is shown to affect the signal line widths.

McDowell, Andrew F.; Adolphi, Natalie L.

2007-09-01

450

Contaminations of herbal products determined by NMR fingerprint.  

PubMed

The utilisation of NMR fingerprinting is proposed as a rapid, available and reliable method to determine the contamination of herbal products. The presence of nimesulide has been reported recently as the contaminant of P.C. 28 Plus, a product based on herbal drugs marketed by the Italian company Cosval. The presence of the substance, as well as its relevant concentration (5%), was first reported by HPLC/MS analysis by other authors. The use of an NMR fingerprint confirmed the previous contamination with nimesulide in P.C. 28 Plus. The same contaminant was also found in P.C. 28 Pink. Furthermore, an analysis of Alergix Plus, another product of the same factory, evidenced the presence of bromhexin. PMID:20803376

Nicoletti, Marcello; Petitto, Valentina

2010-09-01

451

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

452

Low-frequency NMR with a non-resonant circuit  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance typically utilizes a tuned resonance circuit with impedance matching to transmit power and receive signal. The efficiency of such a tuned coil is often described in terms of the coil quality factor, Q. However, in field experiments such as in well-logging, the circuit Q can vary dramatically throughout the depth of the wellbore due to temperature or fluid salinity variations. Such variance can result in erroneous setting of NMR circuit parameters (tuning and matching) and subsequent errors in measurements. This paper investigates the use of a non-resonant transmitter to reduce the circuit sensitivity on Q and demonstrates that such circuits can be efficient in delivering power and current to the coil. We also describe a tuned receiver circuit whose resonant frequency can be controlled digitally. Experimental results show that a range of common NMR experiments can be performed with our circuits.

Hopper, Timothy; Mandal, Soumyajit; Cory, David; Hürlimann, Martin; Song, Yi-Qiao

2011-05-01

453

Low-frequency NMR with a non-resonant circuit.  

PubMed

Nuclear magnetic resonance typically utilizes a tuned resonance circuit with impedance matching to transmit power and receive signal. The efficiency of such a tuned coil is often described in terms of the coil quality factor, Q. However, in field experiments such as in well-logging, the circuit Q can vary dramatically throughout the depth of the wellbore due to temperature or fluid salinity variations. Such variance can result in erroneous setting of NMR circuit parameters (tuning and matching) and subsequent errors in measurements. This paper investigates the use of a non-resonant transmitter to reduce the circuit sensitivity on Q and demonstrates that such circuits can be efficient in delivering power and current to the coil. We also describe a tuned receiver circuit whose resonant frequency can be controlled digitally. Experimental results show that a range of common NMR experiments can be performed with our circuits. PMID:21382732

Hopper, Timothy; Mandal, Soumyajit; Cory, David; Hürlimann, Martin; Song, Yi-Qiao

2011-05-01

454

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.

455

Solution NMR of signal peptidase, a membrane protein  

PubMed Central

Useful solution nuclear magnetic resonance (NMR) data can be obtained from full-length, enzymatically active type I signal peptidase (SPase I), an integral membrane protein, in detergent micelles. Signal peptidase has two transmembrane segments, a short cytoplasmic loop, and a 27-kD C-terminal catalytic domain. It is a critical component of protein transport systems, recognizing and cleaving amino-terminal signal peptides from preproteins during the final stage of their export. Its structure and interactions with the substrate are of considerable interest, but no three-dimensional structure of the whole protein has been reported. The structural analysis of intact membrane proteins has been challenging and only recently has significant progress been achieved using NMR to determine membrane protein structure. Here we employ NMR spectroscopy to study the structure of the full-length SPase I in dodecylphosphocholine detergent micelles. HSQC-TROSY spectra showed resonances corresponding to approximately 3/4 of the 324 residues in the protein. Some sequential assignments were obtained from the 3D HNCACB, 3D HNCA, and 3D HN(CO) TROSY spectra of uniformly 2H, 13C, 15N-labeled full-length SPase I. The assigned residues suggest that the observed spectrum is dominated by resonances arising from extramembraneous portions of the protein and that the transmembrane domain is largely absent from the spectra. Our work elucidates some of the challenges of solution NMR of large membrane proteins in detergent micelles as well as the future promise of these kinds of studies. PMID:18177734

Musial-Siwek, Monika; Kendall, Debra A.; Yeagle, Philip L.

2008-01-01

456

The study of methane adsorbed on porous silicon by NMR  

E-print Network

lie in layers of hexagonal svmmetry. They reported NMR data on the dynamics as- sociated with phase transitions occurring in the methane monolayer between 45 K and 110 K. J. B. Aubrey l presented an investigation of a spontaneous magnetic Journal... and provide supporting ev- idence of the existence of a spontaneous magnetic coupling between the two di- mensional system and the substrate. However, more research needs to be done in order to characterize the interaction and build up a reasonably accurate...

Czermak, Adam Kazimierz

2012-06-07

457

Deuteron NMR Study of Monolayer Thick Films of Nematogenic Molecules  

Microsoft Academic Search

We present a deuteron NMR study of molecular thickness films of a nematogenic material in cylindrical pores. Compared to liquid crystal in bulk or completely filling the pores, a reduced quadrupole splitting is found. It strongly depends on thickness, but only weakly on temperature, even crossing the bulk nematic-isotropic transition. This demonstrates the presence of a 2D-like film that eventually

Bostjan Zalar; Slobodan Zumer; Daniele Finotello

2000-01-01

458

NMR analysis, protonation equilibria and decomposition kinetics of tolperisone.  

PubMed

The rate constants of spontaneous and hydroxide-catalyzed decomposition and the tautomer-specific protonation constants of tolperisone, a classical muscle relaxant were determined. A solution NMR method without any separation techniques was elaborated to quantitate the progress of decomposition. All the rate and equilibrium constants were determined at four different temperatures and the activation parameters were calculated. The molecular mechanism of decomposition is proposed. PMID:19577875

Orgován, Gábor; Tihanyi, Károly; Noszál, Béla

2009-12-01

459

NMR investigation of gaseous SF6 confinement into EPDM rubber.  

PubMed

The confinement process of gaseous sulphurhexafluoride (SF6) in ethylene-propylene-diene (EPDM) rubber was investigated by spectroscopic and spatially resolved NMR techniques. A strong elongation of T1 relaxation time of SF6 and a decrease of the diffusion coefficient were found. A possible explanation may be the strong restriction of molecular mobility due to interactions between SF6 and active centers of the EPDM. PMID:15833636

Neutzler, Sven; Terekhov, Maxim; Hoepfel, Dieter; Oellrich, Lothar Rainer

2005-02-01

460

Figure 1. In vivo 1 H NMR spectra of the  

E-print Network

Figure 1. In vivo 1 H NMR spectra of the hippocampus (bottom row), thalamus (middle row in thalamus (white), striatum (gray) and hippocampus (black) quantified in LCModel. Error bars represent ), thalamus (6.5 x 3.5 x 2.5 mm3 ) and striatum (7.7 x 3.0 x 3.0 mm3 ) were selected based on MR images