Science.gov

Sample records for 19f magic angle

  1. Homonuclear dipolar recoupling under ultra-fast magic-angle spinning: probing 19F-19F proximities by solid-state NMR.

    PubMed

    Wang, Qiang; Hu, Bingwen; Lafon, Olivier; Trébosc, Julien; Deng, Feng; Amoureux, Jean-Paul

    2010-03-01

    We describe dipolar recoupling methods that accomplish, at high magic-angle spinning (MAS) frequencies, the excitation of double-quantum (DQ) coherences between spin-1/2 nuclei. We employ rotor-synchronized symmetry-based pulse sequences which are either gamma-encoded or non-gamma-encoded. The sensitivity and the robustness to both chemical-shift anisotropy and offset are examined. We also compare different techniques to avoid signal folding in the indirect dimension of two-dimensional double-quantum<-->single-quantum (DQ-SQ) spectra. This comprehensive analysis results in the identification of satisfactory conditions for dipolar (19)F-(19)F recoupling at high magnetic fields and high MAS frequencies. The utility of these recoupling methods is demonstrated with high-resolution DQ-SQ NMR spectra, which allow probing (19)F-(19)F proximities in powered fluoroaluminates. PMID:20044288

  2. 19F Magic angle spinning NMR reporter molecules: empirical measures of surface shielding, polarisability and H-bonding.

    PubMed

    Budarin, Vitaliy L; Clark, James H; Deswarte, Fabien E I; Mueller, Karl T; Tavener, Stewart J

    2007-06-14

    Magic Angle Spinning (MAS) (19)F NMR spectra have been obtained and chemical shifts measured for 37 molecules in the gas phase and adsorbed on the surfaces of six common materials: octadecyl- and octyl-functionalised chromatography silicas, Kieselgel 100 silica, Brockmann neutral alumina, Norit activated charcoal and 3-(1-piperidino)propyl functionalised silica. From these six surfaces, octadecyl-silica is selected as a non-polar reference to which the others are compared. The change in chemical shift of a fluorine nucleus within a molecule on adsorption to a surface from the gas phase, Deltadelta(gas)(surface), is described by the empirical relationship: Deltadelta(gas)(surface) = delta(s) + (alpha(s)+pi(s))/alpha(r) (Deltadelta(gas)(reference) - delta(r)) + delta(HBA) + delta(HBD), where delta(s) and delta(r) are constants that describe the chemical shift induced by the electromagnetic field of the surface under investigation and reference surface, alpha(s) and alpha(r) are the relative surface polarisability for the surface and reference, pi(s) is an additional contribution to the surface polarisabilities due to its ability to interact with aromatic molecules, and delta(HBA) and delta(HBD) are measurements of the hydrogen acceptor and donor properties of the surface. These empirical parameters are measured for the surfaces under study. Silica and alumina are found to undergo specific interactions with aromatic reporter molecules and both accept and donate H-bonds. Activated charcoal was found to have an extreme effect on shielding but no specific interactions with the adsorbed molecules. 3-(1-Piperidino)propyl functionalised silica exhibits H-bond acceptor ability, but does not donate H-bonds. PMID:17487325

  3. Trifluoroethanol and 19F magic angle spinning nuclear magnetic resonance as a basic surface hydroxyl reactivity probe for zirconium(IV) hydroxide structures.

    PubMed

    DeCoste, Jared B; Glover, T Grant; Mogilevsky, Gregory; Peterson, Gregory W; Wagner, George W

    2011-08-01

    A novel technique for determining the relative accessibility and reactivity of basic surface hydroxyl sites by reacting various zirconium(IV) hydroxide materials with 2,2,2-trifluoroethanol (TFE) and characterizing the resulting material using (19)F magic angle spinning (MAS) nuclear magnetic resonance (NMR) is presented here. Studied here are three zirconium hydroxide samples, two unperturbed commercial materials, and one commercial material that is crushed by a pellet press. Factors, such as the ratio of bridging/terminal hydroxyls, surface area, and pore size distribution, are examined and found to affect the ability of the zirconium(IV) hydroxide to react with TFE. X-ray diffraction, nitrogen isotherms, and (1)H MAS NMR were used to characterize the unperturbed materials, while thermogravitric analysis with gas chromatography and mass spectrometry along with the (19)F MAS NMR were used to characterize the materials that were reacted with TFE. Zirconium hydroxide materials with a high surface area and a low bridging/terminal hydroxyl ratio were found to react TFE in the greatest amounts. PMID:21699226

  4. 'Magic Angle Precession'

    SciTech Connect

    Binder, Bernd

    2008-01-21

    An advanced and exact geometric description of nonlinear precession dynamics modeling very accurately natural and artificial couplings showing Lorentz symmetry is derived. In the linear description it is usually ignored that the geometric phase of relativistic motion couples back to the orbital motion providing for a non-linear recursive precession dynamics. The high coupling strength in the nonlinear case is found to be a gravitomagnetic charge proportional to the precession angle and angular velocity generated by geometric phases, which are induced by high-speed relativistic rotations and are relevant to propulsion technologies but also to basic interactions. In the quantum range some magic precession angles indicating strong coupling in a phase-locked chaotic system are identified, emerging from a discrete time dynamical system known as the cosine map showing bifurcations at special precession angles relevant to heavy nuclei stability. The 'Magic Angle Precession' (MAP) dynamics can be simulated and visualized by cones rolling in or on each other, where the apex and precession angles are indexed by spin, charge or precession quantum numbers, and corresponding magic angles. The most extreme relativistic warping and twisting effect is given by the Dirac spinor half spin constellation with 'Hyperdiamond' MAP, which resembles quark confinement.

  5. Improved Quantitative 19F MR Molecular Imaging With Flip Angle Calibration and B1-Mapping Compensation

    PubMed Central

    Goette, Matthew J.; Lanza, Gregory M.; Caruthers, Shelton D.; Wickline, Samuel A.

    2014-01-01

    Purpose To improve 19F flip angle calibration and compensate for B1 inhomogeneities in quantitative 19F MRI of sparse molecular epitopes with perfluorocarbon (PFC) nanoparticle (NP) emulsion contrast agents. Materials and Methods Flip angle sweep experiments on PFC-NP point source phantoms with three custom-designed 19F/1H dual-tuned coils revealed a difference in required power settings for 19F and 1H nuclei, which was used to calculate a calibration ratio specific for each coil. An image-based correction technique was developed using B1-field mapping on 1H to correct for 19F and 1H images in two phantom experiments. Results Optimized 19F peak power differed significantly from that of 1H power for each coil (p<0.05). A ratio of 19F/1H power settings yielded a coil-specific and spatially independent calibration value (surface: 1.48±0.06; semi-cylindrical: 1.71±0.02, single-turn-solenoid: 1.92±0.03). 1H-image-based B1 correction equalized the signal intensity of 19F images for two identical 19F PFC-NP samples placed in different parts of the field, which were offset significantly by ~66% (p<0.001) before correction. Conclusion 19F flip angle calibration and B1-mapping compensations to the 19F images employing the more abundant 1H signal as a basis for correction result in a significant change in the quantification of sparse 19F MR signals from targeted PFC NP emulsions. PMID:25425244

  6. New magic angle bumps and magic translation bumps

    SciTech Connect

    Seeman, J.

    1983-10-28

    SLC beams of opposite charge can be transversely deflected in the same direction by RF fields in the accelerating cavities caused by girder tilts, coupler-asymmetries, or manufacturing errors. A symmetric deflection can be corrected by a magic angle bump if the deflection is located adjacent to one of the linac quadrupoles. However, if the deflection is located between quadrupoles, two magic angle bumps or a magic angle bump and a magic translation bump are needed for the correction. Several examples of translation bumps are included. A new magic angle bump is also presented which is longitudinally compressed and has significantly reduced particle excursions. Finally, if new correctors are added midway along the girders so that the number of correctors are doubled, then the longitudinal extent and the maximum particle excursion of these new magic bumps can be further reduced.

  7. MAGIC SHIMMING: gradient shimming with magic angle sample spinning.

    PubMed

    Nishiyama, Yusuke; Tsutsumi, Yu; Utsumi, Hiroaki

    2012-03-01

    A simple method to automatically shim NMR samples spinning at the magic angle is introduced based on the gradient shimming approach. The field inhomogeneity along the spinning axis is measured and automatically corrected. The combination of a normal magic angle spinning (MAS) probe, a conventional homospoil gradient, and a set of properly chosen standard room-temperature shims are used to perform the gradient shimming of samples spinning at the magic angle. The resulting (13)C NMR adamantane linewidth is less than 1 Hz (0.0078 ppm at 11.7 T). PMID:22370722

  8. MAGIC SHIMMING: Gradient shimming with magic angle sample spinning

    NASA Astrophysics Data System (ADS)

    Nishiyama, Yusuke; Tsutsumi, Yu; Utsumi, Hiroaki

    2012-03-01

    A simple method to automatically shim NMR samples spinning at the magic angle is introduced based on the gradient shimming approach. The field inhomogeneity along the spinning axis is measured and automatically corrected. The combination of a normal magic angle spinning (MAS) probe, a conventional homospoil gradient, and a set of properly chosen standard room-temperature shims are used to perform the gradient shimming of samples spinning at the magic angle. The resulting 13C NMR adamantane linewidth is less than 1 Hz (0.0078 ppm at 11.7 T).

  9. The magic angle: a solved mystery.

    PubMed

    Jouffrey, B; Schattschneider, P; Hébert, C

    2004-12-01

    We resolve the long-standing mysterious discrepancy between the experimental magic angle in EELS--approximately 2theta(E)--and the quantum mechanical prediction of approximately 4theta(E). A relativistic approach surpassing the usually applied kinematic correction yields a magic angle close to the experimental value. The reason is that the relativistic correction of the inelastic scattering cross section in anisotropic systems is significantly higher than in isotropic ones. PMID:15556701

  10. Magic Angle Spinning NMR of Viruses

    PubMed Central

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

    2015-01-01

    Viruses, relatively simple pathogens, are able to replicate in many living organisms and to adapt to various environments. Conventional atomic-resolution structural biology techniques, X-ray crystallography and solution NMR spectroscopy provided abundant information on the structures of individual proteins and nucleic acids comprising viruses; however, viral assemblies are not amenable to analysis by these techniques because of their large size, insolubility, and inherent lack of long-range order. In this article, we review the recent advances in magic angle spinning NMR spectroscopy that enabled atomic-resolution analysis of structure and dynamics of large viral systems and give examples of several exciting case studies. PMID:25919197

  11. Broadband "Infinite-Speed" Magic-Angle Spinning NMR Spectroscopy

    SciTech Connect

    Hu, Yan-Yan; Levin, E.M; Schmidt-Rohr, Klaus

    2009-06-02

    High-resolution magic-angle spinning NMR of high-Z spin- 1/2 nuclei such as {sup 125}Te, {sup 207}Pb, {sup 119}Sn, {sup 113}Cd, and {sup 195}Pt is often hampered by large (>1000 ppm) chemical-shift anisotropies, which result in strong spinning sidebands that can obscure the centerbands of interest. In various tellurides with applications as thermoelectrics and as phase-change materials for data storage, even 22-kHz magic-angle spinning cannot resolve the center- and sidebands broadened by chemical-shift dispersion, which precludes peak identification or quantification. For sideband suppression over the necessary wide spectral range (up to 200 kHz), radio frequency pulse sequences with few, short pulses are required. We have identified Gan's two-dimensional magic-angle-turning (MAT) experiment with five 90{sup o} pulses as a promising broadband technique for obtaining spectra without sidebands. We have adapted it to broad spectra and fast magic-angle spinning by accounting for long pulses (comparable to the dwell time in t{sub 1}) and short rotation periods. Spectral distortions are small and residual sidebands negligible even for spectra with signals covering a range of 1.5 {gamma}B{sub 1}, due to a favorable disposition of the narrow ranges containing the signals of interest in the spectral plane. The method is demonstrated on various technologically interesting tellurides with spectra spanning up to 170 kHz, at 22 kHz MAS.

  12. Magic-angle-spinning NMR studies of zeolite SAPO-5

    NASA Astrophysics Data System (ADS)

    Freude, D.; Ernst, H.; Hunger, M.; Pfeifer, H.; Jahn, E.

    1988-01-01

    SAPO-5 was synthesized using triethylamine as template. Magic-angle-spinning (MAS) NMR of 1H, 27Al, 29Si and 31P was used to study the silicon incorporation into the framework and the nature of the Brønsted sites. 1H MAS NMR shows two types of bridging hydroxyl groups. 29Si MAS NMR indicates that silicon substitutes mostly for phosphorus and that there is a small amount of crystalline SiO 2 in the zeolite powder.

  13. NMR in rotating magnetic fields: Magic angle field spinning

    SciTech Connect

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

    2004-09-10

    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.

  14. HYDROGEN AND DEUTERIUM NMR OF SOLIDS BY MAGIC ANGLE SPINNING

    SciTech Connect

    Eckman, R.R.

    1982-10-01

    The nuclear magnetic resonance of solids has long been characterized by very large spectral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. For example, the homonuclear dipolar broadening, HD, for hydrogen is usually several tens of kilohertz. For deuterium, HD is relatively small; however, the quadrupole interaction causes a broadening which can be hundreds of kilohertz in polycrystalline or amorphous solids. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, {beta}{sub m} = Arccos(3{sup -1/2}), with respect to the direction of the external magnetic field. Two approaches have been developed for each nucleus. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of {beta}. A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H{sub D} was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal

  15. Methods for magnetic resonance analysis using magic angle technique

    DOEpatents

    Hu, Jian Zhi; Wind, Robert A.; Minard, Kevin R.; Majors, Paul D.

    2011-11-22

    Methods of performing a magnetic resonance analysis of a biological object are disclosed that include placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. In particular embodiments the method includes pulsing the radio frequency to provide at least two of a spatially selective read pulse, a spatially selective phase pulse, and a spatially selective storage pulse. Further disclosed methods provide pulse sequences that provide extended imaging capabilities, such as chemical shift imaging or multiple-voxel data acquisition.

  16. High-resolution NMR of anisotropic samples with spinning away from the magic angle

    SciTech Connect

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

    2003-03-31

    High-resolution NMR of samples in the solid state is typically performed under mechanical sample spinning around an axis that makes an angle, called the magic angle, of 54.7 degrees with the static magnetic field. There are many cases in which geometrical and engineering constraints prevent spinning at this specific angle. Implementations of in-situ and ex-situ magic angle field spinning might be extremely demanding because of the power requirements or an inconvenient sample size or geometry. Here we present a methodology based on switched angle spinning between two angles, none of which is the magic angle, which provide both isotropic and anisotropic information. Using this method, named Projected Magic Angle Spinning, we were able to obtain resolved isotropic chemical shifts in spinning samples where the broadening is mostly inhomogeneous.

  17. Structure of (NH4)3GaF6 investigated by multinuclear magic-angle spinning NMR spectroscopy in comparison with rietveld refinement.

    PubMed

    Krahl, Thoralf; Ahrens, Mike; Scholz, Gudrun; Heidemann, Detlef; Kemnitz, Erhard

    2008-01-21

    The structure of ammonium gallium cryolite (NH(4))(3)GaF(6) was investigated by (19)F and (69,71)Ga magic-angle spinning (MAS) NMR in comparison with X-ray powder diffraction followed by Rietveld refinement. In agreement with previous thermodynamic measurements, NMR experiments on (NH(4))(3)GaF(6) support the model of rigid GaF(6) octahedra. At high spinning speeds (30 kHz), the scalar coupling between the six equivalent (19)F nuclei and (69,71)Ga can be directly observed in the powder spectra. The coupling constants are J(19)F(69)Ga = 197 Hz and J(19)F(71)Ga = 264 Hz. To explain the (71)Ga spectra recorded at 3 kHz a small distribution of quadrupolar frequencies has to be included. The spread of the spinning sidebands hints to a largest nu(Q) value of 28 kHz for (71)Ga. This can be explained by the occurrence of highly symmetric GaF(6) octahedra, which are tilted against the surrounding atoms. In addition, the incomplete motional excitation does not average out the quadrupolar effects. NMR findings are in discrepancy to those of Rietveld refinement. As result it appears that X-ray diffraction is not sensitive enough to deliver proper results. PMID:18069821

  18. Ultrashort TE T1ρ magic angle imaging.

    PubMed

    Du, Jiang; Statum, Sheronda; Znamirowski, Richard; Bydder, Graeme M; Chung, Christine B

    2013-03-01

    An ultrashort TE T(1)ρ sequence was used to measure T(1) ρ of the goat posterior cruciate ligament (n = 1) and human Achilles tendon specimens (n = 6) at a series of angles relative to the B(0) field and spin-lock field strengths to investigate the contribution of dipole-dipole interaction to T(1)ρ relaxation. Preliminary results showed a significant magic angle effect. T(1)ρ of the posterior cruciate ligament increased from 6.9 ± 1.3 ms at 0° to 36 ± 5 ms at 55° and then gradually reduced to 12 ± 3 ms at 90°. Mean T(1)ρ of the Achilles tendon increased from 5.5 ± 2.2 ms at 0° to 40 ± 5 ms at 55°. T(1)ρ dispersion study showed a significant T(1)ρ increase from 2.3 ± 0.9 ms to 11 ± 3 ms at 0° as the spin-lock field strength increased from 150 Hz to 1 kHz, and from 30 ± 3 ms to 42 ± 4 ms at 55° as the spin-lock field strength increased from 100 to 500 Hz. These results suggest that dipolar interaction is the dominant T(1)ρ relaxation mechanism in tendons and ligaments. PMID:22539354

  19. High-pressure magic angle spinning nuclear magnetic resonance

    SciTech Connect

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. Finally, as an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg2SiO4) reacted with supercritical CO2 and H2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  20. High-pressure magic angle spinning nuclear magnetic resonance.

    PubMed

    Hoyt, David W; Turcu, Romulus V F; Sears, Jesse A; Rosso, Kevin M; Burton, Sarah D; Felmy, Andrew R; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ(13)C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg(2)SiO(4)) reacted with supercritical CO(2) and H(2)O at 150 bar and 50°C are reported, with relevance to geological sequestration of carbon dioxide. PMID:21862372

  1. High-pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg 2SiO 4) reacted with supercritical CO 2 and H 2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  2. Solid effect in magic angle spinning dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω _0 ^{ - 2} field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect.

  3. Solid effect in magic angle spinning dynamic nuclear polarization

    PubMed Central

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-01-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\omega _0 ^{ - 2}\\end{equation*} \\end{document}ω0−2 field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements

  4. Solid effect in magic angle spinning dynamic nuclear polarization.

    PubMed

    Corzilius, Björn; Smith, Albert A; Griffin, Robert G

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω(0)(-2) field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ε = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of (1)H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear (1)H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. PMID:22894339

  5. High-resolution NMR spectroscopy of biological tissues usingprojected Magic Angle Spinning

    SciTech Connect

    Martin, Rachel W.; Jachmann, Rebecca C.; Sakellariou, Dimitris; Nielsen, Ulla Gro; Pines, Alexander

    2005-01-27

    High-resolution NMR spectra of materials subject toanisotropic broadening are usually obtained by rotating the sample aboutthe magic angle, which is 54.7 degrees to the static magnetic field. Inprojected Magic Angle Spinning (p-MAS), the sample is spun about twoangles, neither of which is the magic angle. This provides a method ofobtaining isotropic spectra while spinning at shallow angles. The p-MASexperiment may be used in situations where spinning the sample at themagic angle is not possible due to geometric or other constraints,allowing the choice of spinning angle to be determined by factors such asthe shape of the sample, rather than by the spin physics. The applicationof this technique to bovine tissue samples is demonstrated as a proof ofprinciple for future biological or medical applications.

  6. Hall Plateaus at magic angles in ultraquantum Bismuth

    NASA Astrophysics Data System (ADS)

    Benoît, Fauqué.

    2009-03-01

    The behaviour of a three-dimensional electron gas in the presence of a magnetic field strong enough to put all carriers in the first Landau level (i.e. beyond the quantum limit) is a longstanding question of theoretical condensed matter physics [1]. This issue has been recently explored by two high-field experiments on elemental semi-metal Bismuth. In a first study of transport coefficients (which are dominated by hole-like carriers), the Nernst coefficient presented three unexpected maxima that are concomitant with quasi-plateaux in the Hall coefficient [2]. In a second series of experiments, torque magnetometry (which mainly probes the three Dirac valley electron pockets) detected a field-induced phase transition [3]. The full understanding of the electron and hole behaviours above the quantum limit of pure Bi is therefore still under debate. In this talk, we will present our measurement of the Hall resistivity and torque magnetometry with magnetic field up to 31 T and rotating in the trigonal-bisectrix plane [4]. The Hall response is dominated by the hole pockets according to its sign as well as the period and the angular dependence of its quantum oscillations. In the vicinity of the quantum limit, it presents additional anomalies which are the fingerprints of the electron pockets. We found that for particular orientations of the magnetic field (namely ``magic angles''), the Hall response becomes field-independent within the experimental resolution around 20T. This drastic dependence of the plateaux on the field orientation provides strong constraints for theoretical scenarios. [4pt] [1] Bertrand I. Halperin, Japanese Journal of Applied Physics, 26, Supplement 26-3 (1987).[0pt] [2] Kamran Behnia, Luis Balicas, Yakov Kopelevich, Science, 317, 1729 (2008).[0pt] [3] Lu Li, J. G. Checkelsky, Y. S. Hor, C. Uher, A. F. Hebard, R. J. Cava, and N. P. Ong , Science, 321, 5888 (2008).[0pt] [4] Benoît Fauqu'e, Luis Balicas, Ilya Sheikin, Jean Paul Issi and Kamran Behnia

  7. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization

    NASA Astrophysics Data System (ADS)

    Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160 K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea -eb - n } during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle

  8. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization.

    PubMed

    Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This

  9. An efficient amplification pulse sequence for measuring chemical shift anisotropy under fast magic-angle spinning.

    PubMed

    Hung, Ivan; Gan, Zhehong

    2011-12-01

    A two-dimensional experiment for measuring chemical shift anisotropy (CSA) under fast magic-angle spinning (MAS) is presented. The chemical shift anisotropy evolution is amplified by a sequence of π-pulses that repetitively interrupt MAS averaging. The amplification generates spinning sideband manifolds in the indirect dimension separated by the isotropic shift along the direct dimension. The basic unit of the pulse sequence is designed based on the magic-angle turning experiment and can be concatenated for larger amplification factors. PMID:21962909

  10. Simple cylindrical magic-angle spinner for NMR studies in electromagnets

    NASA Astrophysics Data System (ADS)

    Mai, Michael T.; Ribeiro, Anthony; Jardetzky, Oleg

    A novel cylindrical magic-angle spinner for use in electromagnet systems is described. It features radial and thrust air bearings and easily constructed rotors of relatively large sample volume (˜0.7 cm 3) assembled into a removable spinner/coil Teflon housing. The design allows stable spinning speeds in the range 0.3 to 2.4 kHz with excellent rotor-to-rotor magic-angle resettabilities. High resolution, solid-state NMR studies are illustrated with 13C NMR spectra for crystalline adamantane and a macromolecule, lysozyme.

  11. Conformation analysis and molecular mobility of ethylene and tetrafluoroethylene copolymer using solid-state 19F MAS and 1H --> 19F CP/MAS NMR spectroscopy.

    PubMed

    Aimi, Keitaro; Ando, Shinji

    2004-07-01

    The changes in the conformation and molecular mobility accompanied by a phase transition in the crystalline domain were analyzed for ethylene (E) and tetrafluoroethylene (TFE) copolymer, ETFE, using variable-temperature (VT) solid-state 19F magic angle spinning (MAS) and 1H --> 19F cross-polarization (CP)/MAS NMR spectroscopy. The shifts of the signals for fluorines in TFE units to higher frequency and the continuing decrease and increase in the T1rho(F) values suggest that conformational exchange motions exist in the crystalline domain between 42 and 145 degrees C. Quantum chemical calculations of magnetic shielding constants showed that the high-frequency shift of TFE units should be induced by trans to gauche conformational changes at the CH2-CF2 linkage in the E-TFE unit. Although the 19F signals of the crystalline domain are substantially overlapped with those of the amorphous domain at ambient probe temperature (68 degrees C), they were successfully distinguished by using the dipolar filter and spin-lock pulse sequences at 145 degrees C. The dipolar coupling constants for the crystalline domain, which can be estimated by fitting the dipolar oscillation behaviors in the 1H --> 19F CP curve, showed a significant decrease with increasing temperature from 42 to 145 degrees C. This is due to the averaging of 1H-19F dipolar interactions originating from the molecular motion in the crystalline domain. The increase in molecular mobility in the crystalline domain was clearly shown by VT T1rho(F) and 1H --> 19F CP measurements in the phase transition temperature range. PMID:15181627

  12. True Pathologic Abnormality versus Artifact Foot Position and Magic Angle Artifact in the Peroneal Tendons with 3T Imaging.

    PubMed

    Horn, Deena B; Meyers, Steven; Astor, William

    2015-09-01

    Magnetic resonance imaging is a commonly ordered examination by many foot and ankle surgeons for ankle pain and suspected peroneal tendon pathologic abnormalities. Magic angle artifact is one of the complexities associated with this imaging modality. Magic angle refers to the increased signal on magnetic resonance images associated with the highly organized collagen fibers in tendons and ligaments when they are orientated at a 55° angle to the main magnetic field. We present several examples from a clinical practice setting using 3T imaging illustrating a substantial reduction in magic angle artifact of the peroneal tendon in the prone plantarflexed position compared with the standard neutral (right angle) position. PMID:26429616

  13. Sealed magic angle spinning nuclear magnetic resonance probe and process for spectroscopy of hazardous samples

    DOEpatents

    Cho, Herman M.; Washton, Nancy M.; Mueller, Karl T.; Sears, Jr., Jesse A.; Townsend, Mark R.; Ewing, James R.

    2016-06-14

    A magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) probe is described that includes double containment enclosures configured to seal and contain hazardous samples for analysis. The probe is of a modular design that ensures containment of hazardous samples during sample analysis while preserving spin speeds for superior NMR performance and convenience of operation.

  14. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    DOEpatents

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  15. Hydrogen and deuterium NMR of solids by magic-angle spinning

    SciTech Connect

    Eckman, R.R.

    1982-10-01

    The nuclear magnetic resonance of solids has long been characterized by very large specral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, ..beta../sub m/ = Arccos (3/sup -1/2/), with respect to the direction of the external magnetic field. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of ..beta... A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H/sub D/ was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal motion. In the general case of large H/sub D/, isotropic spectra were obtained by dilution of /sup 1/H with /sup 2/H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids.

  16. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2004-12-28

    A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

  17. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2003-12-30

    A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

  18. Discrete magic angle turning system, apparatus, and process for in situ magnetic resonance spectroscopy and imaging

    DOEpatents

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Wind, Robert A.

    2009-05-19

    Described are a "Discrete Magic Angle Turning" (DMAT) system, devices, and processes that combine advantages of both magic angle turning (MAT) and magic angle hopping (MAH) suitable, e.g., for in situ magnetic resonance spectroscopy and/or imaging. In an exemplary system, device, and process, samples are rotated in a clockwise direction followed by an anticlockwise direction of exactly the same amount. Rotation proceeds through an angle that is typically greater than about 240 degrees but less than or equal to about 360 degrees at constant speed for a time applicable to the evolution dimension. Back and forth rotation can be synchronized and repeated with a special radio frequency (RF) pulse sequence to produce an isotropic-anisotropic shift 2D correlation spectrum. The design permits tubes to be inserted into the sample container without introducing plumbing interferences, further allowing control over such conditions as temperature, pressure, flow conditions, and feed compositions, thus permitting true in-situ investigations to be carried out.

  19. Excitation of multiple quantum transitions under magic angle spinning conditions: Adamantane

    NASA Astrophysics Data System (ADS)

    Meier, B. H.; Earl, William L.

    1986-11-01

    A pulse sequence designed for the excitation of multiple quantum transitions in magic angle spinning solid state NMR spectroscopy is presented. It is shown that under the action of the standard time-reversal pulse sequence, the change in the sign of the dipole coupling (which is used to generate the multiple quantum coherences) upon rotation causes the multiple quantum intensity to vanish after each rotor period. This effect is demonstrated both in calculations and in experimental 1H spectra of adamantane. A modification of the time-reversal pulse sequence, which involves switching the phase of the rf pulses every half-rotor period causes the spin part of the Hamiltonian to switch sign in synchrony with the modulation of the spacial part. This allows the creation of multiple quantum coherences in solids with magic angle spinning. The effectiveness of this pulse sequence is demonstrated through calculations and experiments.

  20. A sensitive, high resolution magic angle turning experiment for measuring chemical shift tensor principal values

    NASA Astrophysics Data System (ADS)

    Alderman, D. W.

    1998-12-01

    A sensitive, high-resolution 'FIREMAT' two-dimensional (2D) magic-angle-turning experiment is described that measures chemical shift tensor principal values in powdered solids. The spectra display spinning-sideband patterns separated by their isotropic shifts. The new method's sensitivity and high resolution in the isotropic-shift dimension result from combining the 5pi magic-angle-turning pulse sequence, an extension of the pseudo-2D sideband-suppression data rearrangement, and the TIGER protocol for processing 2D data. TPPM decoupling is used to enhance resolution. The method requires precise synchronization of the pulses and sampling to the rotor position. It is shown that the technique obtains 35 natural-abundance 13C tensors from erythromycin in 19 hours, and high quality naturalabundance 15N tensors from eight sites in potassium penicillin V in three days on a 400MHz spectrometer.

  1. Excitation of multiple quantum transitions under magic angle spinning conditions: Adamantane

    SciTech Connect

    Meier, B.H.; Earl, W.L.

    1986-11-01

    A pulse sequence designed for the excitation of multiple quantum transitions in magic angle spinning solid state NMR spectroscopy is presented. It is shown that under the action of the standard time-reversal pulse sequence, the change in the sign of the dipole coupling (which is used to generate the multiple quantum coherences) upon rotation causes the multiple quantum intensity to vanish after each rotor period. This effect is demonstrated both in calculations and in experimental /sup 1/H spectra of adamantane. A modification of the time-reversal pulse sequence, which involves switching the phase of the rf pulses every half-rotor period causes the spin part of the Hamiltonian to switch sign in synchrony with the modulation of the spacial part. This allows the creation of multiple quantum coherences in solids with magic angle spinning. The effectiveness of this pulse sequence is demonstrated through calculations and experiments.

  2. Spin-locking and cross-polarization under magic-angle spinning of uniformly labeled solids.

    PubMed

    Hung, Ivan; Gan, Zhehong

    2015-07-01

    Spin-locking and cross-polarization under magic-angle spinning are investigated for uniformly (13)C and (15)N labeled solids. In particular, the interferences from chemical shift anisotropy, and (1)H heteronuclear and (13)C homonuclear dipolar couplings are identified. The physical origin of these interferences provides guidelines for selecting the best (13)C and (15)N polarization transfer rf fields. Optimal settings for both the zero- and double-quantum cross-polarization transfer mechanisms are recommended. PMID:25965280

  3. NMR high-resolution magic angle spinning rotor design for quantification of metabolic concentrations

    NASA Astrophysics Data System (ADS)

    Holly, R.; Damyanovich, A.; Peemoeller, H.

    2006-05-01

    A new high-resolution magic angle spinning nuclear magnetic resonance technique is presented to obtain absolute metabolite concentrations of solutions. The magnetic resonance spectrum of the sample under investigation and an internal reference are acquired simultaneously, ensuring both spectra are obtained under the same experimental conditions. The robustness of the technique is demonstrated using a solution of creatine, and it is shown that the technique can obtain solution concentrations to within 7% or better.

  4. Spin-locking and cross-polarization under magic-angle spinning of uniformly labeled solids

    NASA Astrophysics Data System (ADS)

    Hung, Ivan; Gan, Zhehong

    2015-07-01

    Spin-locking and cross-polarization under magic-angle spinning are investigated for uniformly 13C and 15N labeled solids. In particular, the interferences from chemical shift anisotropy, and 1H heteronuclear and 13C homonuclear dipolar couplings are identified. The physical origin of these interferences provides guidelines for selecting the best 13C and 15N polarization transfer rf fields. Optimal settings for both the zero- and double-quantum cross-polarization transfer mechanisms are recommended.

  5. Solid-state proton multiple-quantum NMR spectroscopy with fast magic angle spinning

    NASA Astrophysics Data System (ADS)

    Geen, Helen; Titman, Jeremy J.; Gottwald, Johannes; Spiess, Hans W.

    1994-09-01

    The feasibility of multiple-quantum NMR spectroscopy with high resolution for protons in solids is explored. A new multiple-quantum excitation sequence suitable for use with fast magic angle spinning is described, and its performance is compared to that of both static and slow-spinning multiple-quantum methods. Modified sequences with scale the rate of development of the multiple-quantum coherences are also demonstrated, and two-dimensional double-quantum spectra of adamantane and polycarbonate are presented.

  6. Microfabricated inserts for magic angle coil spinning (MACS) wireless NMR spectroscopy.

    PubMed

    Badilita, Vlad; Fassbender, Birgit; Kratt, Kai; Wong, Alan; Bonhomme, Christian; Sakellariou, Dimitris; Korvink, Jan G; Wallrabe, Ulrike

    2012-01-01

    This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS) NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i) reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii) improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the "magic angle" of 54.74° with respect to the direction of the magnetic field (magic angle spinning - MAS), accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii) given the high spinning rates (tens of kHz) involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz) testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds. PMID:22936994

  7. An isotropic chemical shift-chemical shift anisotropic correlation experiment using discrete magic angle turning.

    PubMed

    Hu, Jian Zhi; Sears, Jesse A; Kwak, Ja Hun; Hoyt, David W; Wang, Yong; Peden, Charles H F

    2009-05-01

    An isotropic-anisotropic shift 2D correlation spectroscopy is introduced that combines the advantages of both magic angle turning (MAT) and magic angle hopping (MAH) technologies. In this new approach, denoted DMAT for "discrete magic angle turning", the sample rotates clockwise followed by an anticlockwise rotation of exactly the same amount with each rotation less or equal than 360 degrees but greater than 240 degrees , with the rotation speed being constant only for times related to the evolution dimension. This back and forth rotation is repeated and synchronized with a special radio frequency (RF) pulse sequence to produce an isotropic-anisotropic shift 2D correlation spectrum. For any spin-interaction of rank-2 such as chemical shift anisotropy, isotropic magnetic susceptibility interaction, and residual homo-nuclear dipolar interaction in biological fluid samples, the projection along the isotropic dimension is a high resolution spectrum. Since a less than 360 degrees sample rotation is involved, the design potentially allows for in situ control over physical parameters such as pressure, flow conditions, feed compositions, and temperature so that true in situ NMR investigations can be carried out. PMID:19246221

  8. Magic-Angle-Spinning NMR Magnet Development: Field Analysis and Prototypes

    PubMed Central

    Voccio, John; Hahn, Seungyong; Park, Dong Keun; Ling, Jiayin; Kim, Youngjae; Bascuñán, Juan; Iwasa, Yukikazu

    2013-01-01

    We are currently working on a program to complete a 1.5 T/75 mm RT bore magic-angle-spinning nuclear magnetic resonance magnet. The magic-angle-spinning magnet comprises a z-axis 0.866-T solenoid and an x-axis 1.225-T dipole, each to be wound with NbTi wire and operated at 4.2 K in persistent mode. A combination of the fields creates a 1.5-T field pointed at 54.74 degrees (magic angle) from the rotation (z) axis. In the first year of this 3-year program, we have completed magnetic analysis and design of both coils. Also, using a winding machine of our own design and fabrication, we have wound several prototype dipole coils with NbTi wire. As part of this development, we have repeatedly made successful persistent NbTi-NbTi joints with this multifilamentary NbTi wire. PMID:24058275

  9. Magic angle and height quantization in nanofacets on SiC(0001) surfaces

    SciTech Connect

    Sawada, Keisuke; Iwata, Jun-Ichi; Oshiyama, Atsushi

    2014-02-03

    We report on the density-functional calculations that provide microscopic mechanism of the facet formation on the SiC (0001) surface. We first identify atom-scale structures of single-, double-, and quad-bilayer steps and find that the single-bilayer (SB) step has the lowest formation energy. We then find that the SB steps are bunched to form a nanofacet with a particular angle relative to the (0001) plane (magic facet angle) and with a discretized height along the (0001) direction (height quantization). We also clarify a microscopic reason for the self-organization of the nanofacet observed experimentally.

  10. Microfabricated Inserts for Magic Angle Coil Spinning (MACS) Wireless NMR Spectroscopy

    PubMed Central

    Badilita, Vlad; Fassbender, Birgit; Kratt, Kai; Wong, Alan; Bonhomme, Christian; Sakellariou, Dimitris; Korvink, Jan G.; Wallrabe, Ulrike

    2012-01-01

    This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS) NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i) reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii) improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the “magic angle” of 54.74° with respect to the direction of the magnetic field (magic angle spinning – MAS), accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii) given the high spinning rates (tens of kHz) involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz) testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds. PMID:22936994

  11. Tethered or adsorbed supported lipid bilayers in nanotubes characterized by deuterium magic angle spinning NMR spectroscopy.

    PubMed

    Wattraint, Olivier; Warschawski, Dror E; Sarazin, Catherine

    2005-04-12

    2H solid-state NMR experiments were performed under magic angle spinning on lipid bilayers oriented into nanotubes arrays, as a new method to assess the geometrical arrangement of the lipids. Orientational information is obtained from the intensities of the spinning sidebands. The lipid bilayers are formed by fusion of small unilamellar vesicles of DMPC-d54 inside a nanoporous anodic aluminum oxide, either by direct adsorption on the support or by tethering through a streptavidin/biotin linker. The results support that the quality of the lipid bilayers alignment is clearly in favor of the tethering rather than an adsorbed strategy. PMID:15807556

  12. On the magic-angle turning and phase-adjusted spinning sidebands experiments.

    PubMed

    Hung, Ivan; Gan, Zhehong

    2010-05-01

    The underlying relation between the magic-angle turning (MAT) and phase-adjusted spinning sidebands (PASS) experiments is examined. The MAT experiment satisfies the PASS conditions for separating spinning sidebands with a non-constant total evolution time and only requires linear t(1) increments of up to one rotor period. The time-domain data of the two experiments are related by a shearing transformation. A combination of the linear evolution-time increments of MAT and simple data processing of PASS are particularly attractive for the implementation of MAT for measuring chemical shift anisotropy. PMID:20202873

  13. High-resolution magic-angle-spinning NMR spectroscopy of intact tissue.

    PubMed

    Giskeødegård, Guro F; Cao, Maria D; Bathen, Tone F

    2015-01-01

    High-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy is a nondestructive technique that is used to obtain the metabolite profile of a tissue sample. This method requires minimal sample preparation. However, it is important to handle the sample with care and keep it frozen during preparation to minimize degradation. Here, we describe a typical protocol for HR-MAS analysis of intact tissue. We also include examples of typical pulse sequence programs and quantification methods that are used today. PMID:25677145

  14. High resolution 11B NMR of magnesium diboride using cryogenic magic angle spinning

    NASA Astrophysics Data System (ADS)

    Beckett, Peter; Denning, Mark S.; Heinmaa, Ivo; Dimri, Mukesh C.; Young, Edward A.; Stern, Raivo; Carravetta, Marina

    2012-09-01

    Static and magic-angle spinning 11B nuclear magnetic resonance (NMR) data at 4.7 T and 8.5 T have been obtained under cryogenic conditions on a diluted sample of magnesium diboride powder in the normal and superconducting state. The data provide accurate information on the magnetic shift and longitudinal relaxation time down to a temperature of 8 K, with a resolution improvement over the entire temperature range. The onset of superconductivity is unaffected by the sample rotation, as revealed by a steep variation of the magnetic shift just below the critical temperature.

  15. The use of variable temperature and magic-angle sample spinning in studies of fulvic acids

    USGS Publications Warehouse

    Earl, W.L.; Wershaw, R. L.; Thorn, K.A.

    1987-01-01

    Intensity distortions and poor signal to noise in the cross-polarization magic-angle sample spinning NMR of fulvic acids were investigated and attributed to molecular mobility in these ostensibly "solid" materials. We have shown that inefficiencies in cross polarization can be overcome by lowering the sample temperature to about -60??C. These difficulties can be generalized to many other synthetic and natural products. The use of variable temperature and cross-polarization intensity as a function of contact time can yield valuable qualitative information which can aid in the characterization of many materials. ?? 1987.

  16. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100 K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered.

  17. Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

    DOEpatents

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H. F.

    2015-11-24

    A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

  18. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR.

    PubMed

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered. PMID:26920834

  19. Measurement of nuclear magnetic dipole—dipole couplings in magic angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Tycko, Robert; Dabbagh, Gary

    1990-10-01

    We describe a method for measuring nuclear magnetic dipole—dipole couplings in NMR spectra of solids undergoing rapid magic angle spinning (MAS). We show in theory, simulations, and experiments that the couplings, which are averaged out by MAS alone, can be recovered by applying simple resonant radiofrequency pulse sequences in synchrony with the sample rotation. Experimental 13C dipolar powder pattern spectra of polycrystalline ( 13CH 3) 2C(OH)SO 3Na obtained in a two-dimensional experiment based on this method are presented. The method provides a means of determining internuclear distances in polycrystalline and noncrystalline solids while retaining the high resolution and sensitivity afforded by MAS.

  20. MATPASS/CPMG: a sensitivity enhanced magic-angle spinning sideband separation experiment for disordered solids.

    PubMed

    Hung, Ivan; Edwards, Trenton; Sen, Sabyasachi; Gan, Zhehong

    2012-08-01

    A Carr-Purcell Meiboom-Gill (CPMG) sensitivity-enhanced spinning sideband separation experiment is presented. The experiment combines the idea of magic-angle turning and phase-adjusted sideband separation (MATPASS), allowing for isotropic/anisotropic chemical shift separation of disordered solids with line widths far greater than the magic-angle spinning frequency. The use of CPMG enhances the sensitivity of the wide-line spectra by an order of magnitude via multiple-echo acquisition. The MATPASS/CPMG protocol involves acquisition of time-domain data using a MAT/CPMG pulse sequence followed by f(1) shearing during data processing to arrive at the PASS representation. Such a protocol has √2 higher sensitivity than the conventional PASS method because all CPMG echo signals are used for the final PASS spectrum. Application of this method is demonstrated using a GeSe₄ glass sample with both ⁷⁷Se isotropic line widths and chemical shift anisotropy that far exceed the spinning frequency. The sideband separation allows for the measurement of chemical shift anisotropy of the disordered solids. PMID:22750637

  1. Magnetic resonance imaging of DNP enhancements in a rotor spinning at the magic angle.

    PubMed

    Perras, Frédéric A; Kobayashi, Takeshi; Pruski, Marek

    2016-03-01

    Simulations performed on model, static, samples have shown that the microwave power is non-uniformly distributed in the magic angle spinning (MAS) rotor when using conventional dynamic nuclear polarization (DNP) instrumentation. Here, we applied the stray-field magic angle spinning imaging (STRAFI-MAS) experiment to generate a spatial map of the DNP enhancements in a full rotor, which is spun at a low rate in a commercial DNP-MAS NMR system. Notably, we observed that the enhancement factors produced in the center of the rotor can be twice as large as those produced at the top of the rotor. Surprisingly, we observed that the largest enhancement factors are observed along the axis of the rotor as opposed to against its walls, which are most directly irradiated by the microwave beam. We lastly observed that the distribution of enhancement factors can be moderately improved by degassing the sample and increasing the microwave power. The inclusion of dielectric particles greatly amplifies the enhancement factors throughout the rotor. The STRAFI-MAS approach can provide useful guidance for optimizing the access of microwave power to the sample, and thereby lead to further increases in sensitivity of DNP-MAS NMR. PMID:26920838

  2. Magnetic resonance imaging of DNP enhancements in a rotor spinning at the magic angle

    DOE PAGESBeta

    Perras, Frederic A.; Kobayashi, Takeshi; Pruski, Marek

    2016-02-23

    Simulations performed on model, static, samples have shown that the microwave power is non-uniformly distributed in the magic angle spinning (MAS) rotor when using conventional dynamic nuclear polarization (DNP) instrumentation. Here, we applied the stray-field magic angle spinning imaging (STRAFI–MAS) experiment to generate a spatial map of the DNP enhancements in a full rotor, which is spun at a low rate in a commercial DNP–MAS NMR system. Notably, we observed that the enhancement factors produced in the center of the rotor can be twice as large as those produced at the top of the rotor. Surprisingly, we observed that themore » largest enhancement factors are observed along the axis of the rotor as opposed to against its walls, which are most directly irradiated by the microwave beam. We lastly observed that the distribution of enhancement factors can be moderately improved by degassing the sample and increasing the microwave power. The inclusion of dielectric particles greatly amplifies the enhancement factors throughout the rotor. Furthermore, the STRAFI–MAS approach can provide useful guidance for optimizing the access of microwave power to the sample, and thereby lead to further increases in sensitivity of DNP–MAS NMR.« less

  3. Magnetic resonance imaging of DNP enhancements in a rotor spinning at the magic angle

    NASA Astrophysics Data System (ADS)

    Perras, Frédéric A.; Kobayashi, Takeshi; Pruski, Marek

    2016-03-01

    Simulations performed on model, static, samples have shown that the microwave power is non-uniformly distributed in the magic angle spinning (MAS) rotor when using conventional dynamic nuclear polarization (DNP) instrumentation. Here, we applied the stray-field magic angle spinning imaging (STRAFI-MAS) experiment to generate a spatial map of the DNP enhancements in a full rotor, which is spun at a low rate in a commercial DNP-MAS NMR system. Notably, we observed that the enhancement factors produced in the center of the rotor can be twice as large as those produced at the top of the rotor. Surprisingly, we observed that the largest enhancement factors are observed along the axis of the rotor as opposed to against its walls, which are most directly irradiated by the microwave beam. We lastly observed that the distribution of enhancement factors can be moderately improved by degassing the sample and increasing the microwave power. The inclusion of dielectric particles greatly amplifies the enhancement factors throughout the rotor. The STRAFI-MAS approach can provide useful guidance for optimizing the access of microwave power to the sample, and thereby lead to further increases in sensitivity of DNP-MAS NMR.

  4. Advanced slow-magic angle spinning probe for magnetic resonance imaging and spectroscopy

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi; Minard, Kevin R.; Rommereim, Donald N.

    2006-01-24

    The present invention relates to a probe and processes useful for magnetic resonance imaging and spectroscopy instruments. More particularly, the invention relates to a MR probe and processes for obtaining resolution enhancements of fluid objects, including live specimens, using an ultra-slow (magic angle) spinning (MAS) of the specimen combined with a modified phase-corrected magic angle turning (PHORMAT) pulse sequence. Proton NMR spectra were measured of the torso and the top part of the belly of a female BALBc mouse in a 2T field, while spinning the animal at a speed of 1.5 Hz. Results show that even in this relatively low field with PHORMAT, an isotropic spectrum is obtained with line widths that are a factor 4.6 smaller than those obtained in a stationary mouse. Resolution of 1H NMR metabolite spectra are thus significantly enhanced. Results indicate that PHORMAT has the potential to significantly increase the utility of 1H NMR spectroscopy for in vivo biochemical, biomedical and/or medical applications involving large-sized biological objects such as mice, rats and even humans within a hospital setting. For small-sized objects, including biological objects, such as excised tissues, organs, live bacterial cells, and biofilms, use of PASS at a spinning rate of 30 Hz and above is preferred.

  5. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2003-11-25

    A method of performing a magnetic resonance analysis of a biological object that includes placing the biological object in a main magnetic field and in a radio frequency field, the main magnetic field having a static field direction; rotating the biological object at a rotational frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. According to another embodiment, the radio frequency is pulsed to provide a sequence capable of producing a spectrum that is substantially free of spinning sideband peaks.

  6. High Resolution 1H NMR Spectroscopy in Rat Liver Using Magic Angle Turning at a 1 Hz Spinning Rate

    SciTech Connect

    Hu, Jian Zhi ); Rommereim, Donald N. ); Wind, Robert A. )

    2001-12-01

    It is demonstrated that a high resolution 1H NMR spectrum of excised rat liver can be obtained using the technique of magic angle turning at a sample spinning rate of 1 Hz. A variant of the phase-corrected magic angle turning (PHORMAT) pulse sequence that includes a water suppression segment was developed for the investigation. The spectral resolution achieved with PHORMAT is approaching that obtained from a standard magic angle spinning experiment at a spinning rate of several kHz. With such ultra-slow spinning, tissue and cell damage associated with the standard MAS experiment is minimized or eliminated. The technique is potentially useful for obtaining high-resolution 1H spectra in live animals.

  7. Magic-angle spinning NMR of intact bacteriophages: Insights into the capsid, DNA and their interface

    NASA Astrophysics Data System (ADS)

    Abramov, Gili; Morag, Omry; Goldbourt, Amir

    2015-04-01

    Bacteriophages are viruses that infect bacteria. They are complex macromolecular assemblies, which are composed of multiple protein subunits that protect genomic material and deliver it to specific hosts. Various biophysical techniques have been used to characterize their structure in order to unravel phage morphogenesis. Yet, most bacteriophages are non-crystalline and have very high molecular weights, in the order of tens of MegaDaltons. Therefore, complete atomic-resolution characterization on such systems that encompass both capsid and DNA is scarce. In this perspective article we demonstrate how magic-angle spinning solid-state NMR has and is used to characterize in detail bacteriophage viruses, including filamentous and icosahedral phage. We discuss the process of sample preparation, spectral assignment of both capsid and DNA and the use of chemical shifts and dipolar couplings to probe the capsid-DNA interface, describe capsid structure and dynamics and extract structural differences between viruses.

  8. Primary processes in isolated Photosystem II reaction centres probed by magic angle transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Klug, David R.; Rech, Thomas; Melissa Joseph, D.; Barber, James; Durrant, James R.; Porter, George

    1995-05-01

    There is currently some disagreement regarding the dominant time constant for formation of the radical pair state P680 +Ph - in isolated photosystem two reaction centres. It has recently been suggested that this disagreement may originate, at least in part, from different polarisations of the pump and probe beams used in optical experiments. In this paper, we present data collected using a magic angle configuration of the pump and probe polarisations. We find that these data support our previous interpretation of data collected using a parallel polarisation configuration. Moreover, we present further evidence to support our conclusion that formation of the P680 +Ph - state primarily occurs with a 21 ps time constant when P680 is directly excited. A 3 ps component is also observed; this component is not associated with a large proportion of the radical pair formation. We discuss our data and interpretation in comparison with those of other groups.

  9. Rapid proton-detected NMR assignment for proteins with fast magic angle spinning.

    PubMed

    Barbet-Massin, Emeline; Pell, Andrew J; Retel, Joren S; Andreas, Loren B; Jaudzems, Kristaps; Franks, W Trent; Nieuwkoop, Andrew J; Hiller, Matthias; Higman, Victoria; Guerry, Paul; Bertarello, Andrea; Knight, Michael J; Felletti, Michele; Le Marchand, Tanguy; Kotelovica, Svetlana; Akopjana, Inara; Tars, Kaspars; Stoppini, Monica; Bellotti, Vittorio; Bolognesi, Martino; Ricagno, Stefano; Chou, James J; Griffin, Robert G; Oschkinat, Hartmut; Lesage, Anne; Emsley, Lyndon; Herrmann, Torsten; Pintacuda, Guido

    2014-09-01

    Using a set of six (1)H-detected triple-resonance NMR experiments, we establish a method for sequence-specific backbone resonance assignment of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of 5-30 kDa proteins. The approach relies on perdeuteration, amide (2)H/(1)H exchange, high magnetic fields, and high-spinning frequencies (ωr/2π ≥ 60 kHz) and yields high-quality NMR data, enabling the use of automated analysis. The method is validated with five examples of proteins in different condensed states, including two microcrystalline proteins, a sedimented virus capsid, and two membrane-embedded systems. In comparison to contemporary (13)C/(15)N-based methods, this approach facilitates and accelerates the MAS NMR assignment process, shortening the spectral acquisition times and enabling the use of unsupervised state-of-the-art computational data analysis protocols originally developed for solution NMR. PMID:25102442

  10. Magic-angle spinning NMR of intact bacteriophages: insights into the capsid, DNA and their interface.

    PubMed

    Abramov, Gili; Morag, Omry; Goldbourt, Amir

    2015-04-01

    Bacteriophages are viruses that infect bacteria. They are complex macromolecular assemblies, which are composed of multiple protein subunits that protect genomic material and deliver it to specific hosts. Various biophysical techniques have been used to characterize their structure in order to unravel phage morphogenesis. Yet, most bacteriophages are non-crystalline and have very high molecular weights, in the order of tens of MegaDaltons. Therefore, complete atomic-resolution characterization on such systems that encompass both capsid and DNA is scarce. In this perspective article we demonstrate how magic-angle spinning solid-state NMR has and is used to characterize in detail bacteriophage viruses, including filamentous and icosahedral phage. We discuss the process of sample preparation, spectral assignment of both capsid and DNA and the use of chemical shifts and dipolar couplings to probe the capsid-DNA interface, describe capsid structure and dynamics and extract structural differences between viruses. PMID:25797007

  11. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    SciTech Connect

    Mance, Deni; Baldus, Marc; Gast, Peter; Huber, Martina; Ivanov, Konstantin L.

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  12. Non-Fermi-liquid magic angle effects in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Lebed, A. G.

    2016-07-01

    We investigate a theoretical problem of electron-electron interactions in an inclined magnetic field in a quasi-one-dimensional (Q1D) conductor. We show that they result in strong non-Fermi-liquid corrections to a specific heat, provided that the direction of the magnetic field is far from the so-called Lebed's magic angles (LMAs). If magnetic field is directed close to one of the LMAs, the specific heat corrections become small and the Fermi-liquid picture restores. As a result, we predict Fermi-liquid-non-Fermi-liquid angular crossovers in the vicinities of the LMA directions of the field. We suggest to perform the corresponding experiment in the Q1D conductor (Per) 2Au (mnt) 2 under pressure in magnetic fields of the order of H ≃25 T .

  13. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Mance, Deni; Gast, Peter; Huber, Martina; Baldus, Marc; Ivanov, Konstantin L.

    2015-06-01

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between "bulk" and "core" nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  14. Efficient dipolar double quantum filtering under magic angle spinning without a 1H decoupling field

    NASA Astrophysics Data System (ADS)

    Courtney, Joseph M.; Rienstra, Chad M.

    2016-08-01

    We present a systematic study of dipolar double quantum (DQ) filtering in 13C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n ⩾ 7, provided that the 13C nutation frequency is on the order of 100 kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between 13C and 1H fields. For 13C nutation frequencies greater than 75 kHz, optimal performance is observed without an applied 1H field. At spinning rates exceeding 20 kHz, symmetry conditions as low as n = 3 were found to perform adequately.

  15. Magic angle spinning solid-state NMR experiments for structural characterization of proteins.

    PubMed

    Shi, Lichi; Ladizhansky, Vladimir

    2012-01-01

    Solid-state nuclear magnetic resonance (SSNMR) has become a prominent method in biology and is suitable for the characterization of insoluble proteins and protein aggregates such as amyloid fibrils, membrane-lipid complexes, and precipitated proteins. Often, the initial and the most critical step is to obtain spectroscopic assignments, that is, to determine chemical shifts of individual atoms. The procedures for SSNMR spectroscopic assignments are now well established for small microcrystalline proteins, where high signal-to-noise can be obtained. The sensitivity of the experiments and spectral resolution decrease with the increasing molecular weight, which makes setting SSNMR experiments in large proteins a much more challenging and demanding procedure. Here, we describe the protocol for the most common set of 3D magic angle spinning (MAS) SSNMR experiments. While the procedures described in the text are well known to SSNMR practitioners, we hope they will be of interest to scientists interested in extending their repertoire of biophysical techniques. PMID:22760319

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

    PubMed

    Schoenberger, Torsten; Simmross, Ulrich; Poppe, Christian

    2016-01-01

    The application of high resolution magic angle spinning (HR-MAS) (1)H NMR spectroscopy is ideally suited for the differentiation of plastics. In addition to the actual material composition, the different types of polymer architectures and tacticity provide characteristic signals in the fingerprint of the (1)H NMR spectra. The method facilitates forensic comparison, as even small amounts of insoluble but swellable plastic particles are utilized. The performance of HR-MAS NMR can be verified against other methods that were recently addressed in various articles about forensic tape comparison. In this study samples of the 90 electrical tapes already referenced by the FBI laboratory were used. The discrimination power of HR-MAS is demonstrated by the fact that more tape groups can be distinguished by NMR spectroscopy than by using the combined evaluation of several commonly used analytical techniques. An additional advantage of this robust and quick method is the very simple sample preparation. PMID:26558760

  17. Magic-angle-spinning NMR studies of acid sites in zeolite H-ZSM-5

    SciTech Connect

    Brunner, E.; Ernst, H.; Freude, D.; Froehlich, T.; Hunger, M.; Pfeifer, H. )

    1991-01-01

    {sup 1}H, {sup 13}C, {sup 27}Al, and {sup 29}Si magic-angle-spinning (MAS) NMR was used to elucidate the nature of the catalytic activity of zeolite H-ZSM-5. {sup 1}H MAS NMR of sealed samples after mild hydrothermal dealumination shows that the enhanced activity for n-hexane cracking is not due to an enhanced Bronstead acidity. The concentrations of the various OH groups and aluminous species suggest that the reason for the enhanced catalytic activity is the interaction of the n-hexane molecule with a bridging hydroxyl group and with extra-framework aluminium species, which give rise to the enhanced activity, cannot be easily removed from their positions, and are therefore immobilized by the zeolitic framework.

  18. Efficient dipolar double quantum filtering under magic angle spinning without a (1)H decoupling field.

    PubMed

    Courtney, Joseph M; Rienstra, Chad M

    2016-08-01

    We present a systematic study of dipolar double quantum (DQ) filtering in (13)C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n⩾7, provided that the (13)C nutation frequency is on the order of 100kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between (13)C and (1)H fields. For (13)C nutation frequencies greater than 75kHz, optimal performance is observed without an applied (1)H field. At spinning rates exceeding 20kHz, symmetry conditions as low as n=3 were found to perform adequately. PMID:27314744

  19. Pulsed field gradient magic angle spinning NMR self-diffusion measurements in liquids.

    PubMed

    Viel, Stéphane; Ziarelli, Fabio; Pagès, Guilhem; Carrara, Caroline; Caldarelli, Stefano

    2008-01-01

    Several investigations have recently reported the combined use of pulsed field gradient (PFG) with magic angle spinning (MAS) for the analysis of molecular mobility in heterogeneous materials. In contrast, little attention has been devoted so far to delimiting the role of the extra force field induced by sample rotation on the significance and reliability of self-diffusivity measurements. The main purpose of this work is to examine this phenomenon by focusing on pure liquids for which its impact is expected to be largest. Specifically, we show that self-diffusion coefficients can be accurately determined by PFG MAS NMR diffusion measurements in liquids, provided that specific experimental conditions are met. First, the methodology to estimate the gradient uniformity and to properly calibrate its absolute strength is briefly reviewed and applied on a MAS probe equipped with a gradient coil aligned along the rotor spinning axis, the so-called 'magic angle gradient' coil. Second, the influence of MAS on the outcome of PFG MAS diffusion measurements in liquids is investigated for two distinct typical rotors of different active volumes, 12 and 50 microL. While the latter rotor led to totally unreliable results, especially for low viscosity compounds, the former allowed for the determination of accurate self-diffusion coefficients both for fast and slowly diffusing species. Potential implications of this work are the possibility to measure accurate self-diffusion coefficients of sample-limited mixtures or to avoid radiation damping interferences in NMR diffusion measurements. Overall, the outlined methodology should be of interest to anyone who strives to improve the reliability of MAS diffusion studies, both in homogeneous and heterogeneous media. PMID:18006344

  20. Magic Angle Spinning NMR Spectroscopy: A Versatile Technique for Structural and Dynamic Analysis of Solid-Phase Systems

    PubMed Central

    Polenova, Tatyana; Gupta, Rupal; Goldbourt, Amir

    2016-01-01

    Magic Angle Spinning (MAS) NMR spectroscopy is a powerful method for analysis of a broad range of systems, including inorganic materials, pharmaceuticals, and biomacromolecules. The recent developments in MAS NMR instrumentation and methodologies opened new vistas to atomic-level characterization of a plethora of chemical environments previously inaccessible to analysis, with unprecedented sensitivity and resolution. PMID:25794311

  1. Magic-angle sample spinning electron paramagnetic resonance--instrumentation, performance, and limitations.

    PubMed

    Hessinger, D; Bauer, C; Hubrich, M; Jeschke, G; Spiess, H W

    2000-12-01

    An electron paramagnetic resonance (EPR) setup for line narrowing experiments with fast sample spinning at variable angles between the rotation axis and the static magnetic field is described and applied in the magic-angle sample spinning (MAS) EPR experiment at X-band frequencies (9.5 GHz). Sample spinning speeds up to 17 kHz at temperatures down to 200 K can be achieved with rotors of 4-mm outer and 2.5-mm inner diameter without severe losses in microwave amplitude compared to standard pulse EPR probeheads. A phase cycle is introduced that provides pure absorption MAS EPR spectra and allows one to distinguish between positive and negative frequency offsets (pseudo-quadrature detection). Possible broadening mechanisms in MAS EPR spectra are discussed. It is demonstrated both by theory and by experiment that the MAS EPR experiment requires excitation bandwidths that are comparable to the total spectral width, since otherwise destructive interference between contributions of spins with similar resonance offsets suppresses the signal. Experimental observations on the E(1) center in gamma-irradiated silica glass and on the SO(-)(3) radical in gamma-irradiated sulfamic acid are reported. PMID:11097812

  2. Recoupling of chemical shift anisotropy by R-symmetry sequences in magic angle spinning NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Hou, Guangjin; Byeon, In-Ja L.; Ahn, Jinwoo; Gronenborn, Angela M.; Polenova, Tatyana

    2012-10-01

    13C and 15N chemical shift (CS) interaction is a sensitive probe of structure and dynamics in a wide variety of biological and inorganic systems, and in the recent years several magic angle spinning NMR approaches have emerged for residue-specific measurements of chemical shift anisotropy (CSA) tensors in uniformly and sparsely enriched proteins. All of the currently existing methods are applicable to slow and moderate magic angle spinning (MAS) regime, i.e., MAS frequencies below 20 kHz. With the advent of fast and ultrafast MAS probes capable of spinning frequencies of 40-100 kHz, and with the superior resolution and sensitivity attained at such high frequencies, development of CSA recoupling techniques working under such conditions is necessary. In this work, we present a family of R-symmetry based pulse sequences for recoupling of 13C/15N CSA interactions that work well in both natural abundance and isotopically enriched systems. We demonstrate that efficient recoupling of either first-rank (σ1) or second-rank (σ2) spatial components of CSA interaction is attained with appropriately chosen γ-encoded RNnv symmetry sequences. The advantage of these γ-encoded RNnv-symmetry based CSA (RNCSA) recoupling schemes is that they are suitable for CSA recoupling under a wide range of MAS frequencies, including fast MAS regime. Comprehensive analysis of the recoupling properties of these RNnv symmetry sequences reveals that the σ1-CSA recoupling symmetry sequences exhibit large scaling factors; however, the partial homonuclear dipolar Hamiltonian components are symmetry allowed, which makes this family of sequences suitable for CSA measurements in systems with weak homonuclear dipolar interactions. On the other hand, the γ-encoded symmetry sequences for σ2-CSA recoupling have smaller scaling factors but they efficiently suppress the homonuclear dipole-dipole interactions. Therefore, the latter family of sequences is applicable for measurements of CSA parameters in

  3. Quantitative neuropathology by high resolution magic angle spinning proton magnetic resonance spectroscopy

    PubMed Central

    Cheng, L. L.; Ma, M. J.; Becerra, L.; Ptak, T.; Tracey, I.; Lackner, A.; González, R. G.

    1997-01-01

    We describe a method that directly relates tissue neuropathological analysis to medical imaging. Presently, only indirect and often tenuous relationships are made between imaging (such as MRI or x-ray computed tomography) and neuropathology. We present a biochemistry-based, quantitative neuropathological method that can help to precisely quantify information provided by in vivo proton magnetic resonance spectroscopy (1HMRS), an emerging medical imaging technique. This method, high resolution magic angle spinning (HRMAS) 1HMRS, is rapid and requires only small amounts of unprocessed samples. Unlike chemical extraction or other forms of tissue processing, this method analyzes tissue directly, thus minimizing artifacts. We demonstrate the utility of this method by assessing neuronal damage using multiple tissue samples from differently affected brain regions in a case of Pick disease, a human neurodegenerative disorder. Among different regions, we found an excellent correlation between neuronal loss shown by traditional neurohistopathology and decrease of the neuronal marker N-acetylaspartate measured by HRMAS 1HMRS. This result demonstrates for the first time, to our knowledge, a direct, quantitative link between a decrease in N-acetylaspartate and neuronal loss in a human neurodegenerative disease. As a quantitative method, HRMAS 1HMRS has potential applications in experimental and clinical neuropathologic investigations. It should also provide a rational basis for the interpretation of in vivo 1HMRS studies of human neurological disorders. PMID:9177231

  4. NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning.

    PubMed

    Shmyreva, Anna A; Safdari, Majid; Furó, István; Dvinskikh, Sergey V

    2016-06-14

    Orders of magnitude decrease of (207)Pb and (199)Hg NMR longitudinal relaxation times T1 upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX2 (Me = Pb, Hg and X = Cl, Br, I). In lead(ii) halides, the most dramatic decrease of T1 relative to that in a static sample is in PbI2, while it is smaller but still significant in PbBr2, and not detectable in PbCl2. The effect is magnetic-field dependent but independent of the spinning speed in the range 200-15 000 Hz. The observed relaxation enhancement is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time. PMID:27306000

  5. High-resolution magic angle spinning 1H MRS in prostate cancer.

    PubMed

    Decelle, Emily A; Cheng, Leo L

    2014-01-01

    Prostate cancer (PCa) is the most frequently diagnosed malignancy in men worldwide, largely as a result of the increased use of the annual serum prostate-specific antigen (PSA) screening test for detection. PSA screening has saved lives, but it has also resulted in the overtreatment of many patients with PCa because of a limited ability to accurately localize and characterize PCa lesions through imaging. High-resolution magic angle spinning (HRMAS) (1)H MRS has proven to be a strong potential clinical tool for PCa diagnosis and prognosis. The HRMAS technique allows valuable metabolic information to be obtained from ex vivo intact tissue samples and also enables the performance of histopathology on the same tissue specimens. Studies have found that the quantification of individual metabolite levels and metabolite ratios, as well as metabolomic profiles, shows strong potential to improve accuracy in PCa detection, diagnosis and monitoring. Ex vivo HRMAS is also a valuable tool for the interpretation of in vivo results, including the localization of tumors, and thus has the potential to improve in vivo diagnostic tests used in the clinic. Here, we primarily review publications of HRMAS (1)H MRS and its use for the study of intact human prostate tissue. PMID:23529951

  6. Magic-angle spinning solid-state multinuclear NMR on low-field instrumentation

    NASA Astrophysics Data System (ADS)

    Sørensen, Morten K.; Bakharev, Oleg; Jensen, Ole; Jakobsen, Hans J.; Skibsted, Jørgen; Nielsen, Niels Chr.

    2014-01-01

    Mobile and cost-effective NMR spectroscopy exploiting low-field permanent magnets is a field of tremendous development with obvious applications for arrayed large scale analysis, field work, and industrial screening. So far such demonstrations have concentrated on relaxation measurements and lately high-resolution liquid-state NMR applications. With high-resolution solid-state NMR spectroscopy being increasingly important in a broad variety of applications, we here introduce low-field magic-angle spinning (MAS) solid-state multinuclear NMR based on a commercial ACT 0.45 T 62 mm bore Halbach magnet along with a homebuilt FPGA digital NMR console, amplifiers, and a modified standard 45 mm wide MAS probe for 7 mm rotors. To illustrate the performance of the instrument and address cases where the low magnetic field may offer complementarity to high-field NMR experiments, we demonstrate applications for 23Na MAS NMR with enhanced second-order quadrupolar coupling effects and 31P MAS NMR where reduced influence from chemical shift anisotropy at low field may facilitate determination of heteronuclear dipole-dipole couplings.

  7. A unified heteronuclear decoupling strategy for magic-angle-spinning solid-state NMR spectroscopy

    SciTech Connect

    Equbal, Asif; Bjerring, Morten; Nielsen, Niels Chr. E-mail: ncn@inano.au.dk; Madhu, P. K. E-mail: ncn@inano.au.dk

    2015-05-14

    A unified strategy of two-pulse based heteronuclear decoupling for solid-state magic-angle spinning nuclear magnetic resonance is presented. The analysis presented here shows that different decoupling sequences like two-pulse phase-modulation (TPPM), X-inverse-X (XiX), and finite pulse refocused continuous wave (rCW{sup A}) are basically specific solutions of a more generalized decoupling scheme which incorporates the concept of time-modulation along with phase-modulation. A plethora of other good decoupling conditions apart from the standard, TPPM, XiX, and rCW{sup A} decoupling conditions are available from the unified decoupling approach. The importance of combined time- and phase-modulation in order to achieve the best decoupling conditions is delineated. The consequences of different indirect dipolar interactions arising from cross terms comprising of heteronuclear and homonuclear dipolar coupling terms and also those between heteronuclear dipolar coupling and chemical-shift anisotropy terms are presented in order to unfold the effects of anisotropic interactions under different decoupling conditions. Extensive numerical simulation results are corroborated with experiments on standard amino acids.

  8. Magnetization transfer magic-angle-spinning z-spectroscopy of excised tissues

    NASA Astrophysics Data System (ADS)

    Avni, Reut; Mangoubi, Oren; Bhattacharyya, Rangeet; Degani, Hadassa; Frydman, Lucio

    2009-07-01

    NMR experiments devised to aid in analyses of tissues include magnetization transfer (MT), which can highlight the signals of biological macromolecules through cross-relaxation and/or chemical exchange processes with the bulk 1H water resonance, and high-resolution magic-angle-spinning (HRMAS) methods, akin to those used in solid-state NMR to introduce additional spectral resolution via the averaging of spin anisotropies. This paper explores the result of combining these methodologies, and reports on MT "z-spectroscopy" between water and cell components in excised tissues under a variety of HRMAS conditions. Main features arising from the resulting 1H "MTMAS" experiments include strong spinning sideband manifolds centered at the liquid water shift, high-resolution isotropic features coinciding with aliphatic and amide proton resonances, and a second sideband manifold arising as spinning speeds are increased. Interpretations are given for the origin of these various features, including simulations shedding further light onto the nature of MT NMR signals observed for tissue samples. Concurrently, histological examinations are reported validating the limits of HRMAS NMR procedures to the analysis of tissue samples preserved in a number of different ways.

  9. NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Shmyreva, Anna A.; Safdari, Majid; Furó, István; Dvinskikh, Sergey V.

    2016-06-01

    Orders of magnitude decrease of 207Pb and 199Hg NMR longitudinal relaxation times T1 upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX2 (Me = Pb, Hg and X = Cl, Br, I). In lead(ii) halides, the most dramatic decrease of T1 relative to that in a static sample is in PbI2, while it is smaller but still significant in PbBr2, and not detectable in PbCl2. The effect is magnetic-field dependent but independent of the spinning speed in the range 200-15 000 Hz. The observed relaxation enhancement is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time.

  10. Structure of fully protonated proteins by proton-detected magic-angle spinning NMR.

    PubMed

    Andreas, Loren B; Jaudzems, Kristaps; Stanek, Jan; Lalli, Daniela; Bertarello, Andrea; Le Marchand, Tanguy; Cala-De Paepe, Diane; Kotelovica, Svetlana; Akopjana, Inara; Knott, Benno; Wegner, Sebastian; Engelke, Frank; Lesage, Anne; Emsley, Lyndon; Tars, Kaspars; Herrmann, Torsten; Pintacuda, Guido

    2016-08-16

    Protein structure determination by proton-detected magic-angle spinning (MAS) NMR has focused on highly deuterated samples, in which only a small number of protons are introduced and observation of signals from side chains is extremely limited. Here, we show in two fully protonated proteins that, at 100-kHz MAS and above, spectral resolution is high enough to detect resolved correlations from amide and side-chain protons of all residue types, and to reliably measure a dense network of (1)H-(1)H proximities that define a protein structure. The high data quality allowed the correct identification of internuclear distance restraints encoded in 3D spectra with automated data analysis, resulting in accurate, unbiased, and fast structure determination. Additionally, we find that narrower proton resonance lines, longer coherence lifetimes, and improved magnetization transfer offset the reduced sample size at 100-kHz spinning and above. Less than 2 weeks of experiment time and a single 0.5-mg sample was sufficient for the acquisition of all data necessary for backbone and side-chain resonance assignment and unsupervised structure determination. We expect the technique to pave the way for atomic-resolution structure analysis applicable to a wide range of proteins. PMID:27489348

  11. A LOW-E MAGIC ANGLE SPINNING PROBE FOR BIOLOGICAL SOLID STATE NMR AT 750 MHz

    PubMed Central

    McNeill, Seth A.; Gor’kov, Peter L.; Shetty, Kiran; Brey, William W.; Long, Joanna R.

    2009-01-01

    Crossed-coil NMR probes are a useful tool for reducing sample heating for biological solid state NMR. In a crossed-coil probe, the higher frequency 1H field, which is the primary source of sample heating in conventional probes, is produced by a separate low-inductance resonator. Because a smaller driving voltage is required, the electric field across the sample and the resultant heating is reduced. In this work we describe the development of a magic angle spinning (MAS) solid state NMR probe utilizing a dual resonator. This dual resonator approach, referred to as “Low-E,” was originally developed to reduce heating in samples of mechanically aligned membranes. The study of inherently dilute systems, such as proteins in lipid bilayers, via MAS techniques requires large sample volumes at high field to obtain spectra with adequate signal-to-noise ratio under physiologically relevant conditions. With the Low-E approach, we are able to obtain homogeneous and sufficiently strong radiofrequency fields for both 1H and 13C frequencies in a 4 mm probe with a 1H frequency of 750 MHz. The performance of the probe using windowless dipolar recoupling sequences is demonstrated on model compounds as well as membrane embedded peptides. PMID:19138870

  12. Alignment of high resolution magic angle spinning magnetic resonance spectra using warping methods.

    PubMed

    Giskeødegård, Guro F; Bloemberg, Tom G; Postma, Geert; Sitter, Beathe; Tessem, May-Britt; Gribbestad, Ingrid S; Bathen, Tone F; Buydens, Lutgarde M C

    2010-12-17

    The peaks of magnetic resonance (MR) spectra can be shifted due to variations in physiological and experimental conditions, and correcting for misaligned peaks is an important part of data processing prior to multivariate analysis. In this paper, five warping algorithms (icoshift, COW, fastpa, VPdtw and PTW) are compared for their feasibility in aligning spectral peaks in three sets of high resolution magic angle spinning (HR-MAS) MR spectra with different degrees of misalignments, and their merits are discussed. In addition, extraction of information that might be present in the shifts is examined, both for simulated data and the real MR spectra. The generic evaluation methodology employs a number of frequently used quality criteria for evaluation of the alignments, together with PLS-DA to assess the influence of alignment on the classification outcome. Peak alignment greatly improved the internal similarity of the data sets. Especially icoshift and COW seem suitable for aligning HR-MAS MR spectra, possibly because they perform alignment segment-wise. The choice of reference spectrum can influence the alignment result, and it is advisable to test several references. Information from the peak shifts was extracted, and in one case cancer samples were successfully discriminated from normal tissue based on shift information only. Based on these findings, general recommendations for alignment of HR-MAS MRS data are presented. Where possible, observations are generalized to other data types (e.g. chromatographic data). PMID:21094376

  13. Frequency-stepped acquisition in nuclear magnetic resonance spectroscopy under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Pell, Andrew J.; Clément, Raphaële J.; Grey, Clare P.; Emsley, Lyndon; Pintacuda, Guido

    2013-03-01

    The nuclear magnetic resonance of paramagnetic solids is usually characterized by the presence of large chemical shifts and shift anisotropies due to hyperfine interactions. Frequently the resulting spectra cover a frequency range of several megahertz, which is greater than the bandwidth of commercially available radio-frequency (RF) probes, making it impossible to acquire the whole spectrum in a single experiment. In these cases it common to record a series of spectra, in which the probe is tuned to a different frequency for each, and then sum the results to give the "true" spectrum. While this method is very widely used on static samples, the application of frequency stepping under magic-angle spinning (MAS) is less common, owing to the increased complexity of the spin dynamics when describing the interplay of the RF irradiation with the mechanical rotation of the shift tensor. In this paper, we present a theoretical description, based on the jolting frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983), 10.1016/0022-2364(83)90279-2], for describing the spin dynamics of a powder sample under MAS when subjected to a selective pulse of low RF-field amplitude. The formalism is used to describe the frequency stepping method under MAS, and under what circumstances the true spectrum is reproduced. We also present an experimental validation of the methodology under ultra-fast MAS with the paramagnetic materials LiMnPO4 and TbCsDPA.

  14. Deuterium magic angle spinning studies of substrates bound to cytochrome P450.

    PubMed

    Lee, H; Ortiz de Montellano, P R; McDermott, A E

    1999-08-17

    We report solid-state deuterium magic angle spinning NMR spectra of perdeuterated adamantane bound to the active site of microcrystalline cytochrome P450cam (CP450cam) in its resting state. CP450cam contains a high-spin ferric (Fe3+) heme in the resting state; the isotropic shift was displaced from the diamagnetic value and varied with temperature consistent with Curie-law dependence. A nondeuterated competitive tighter binding ligand, camphor, was used to displace the adamantane-bound species. This addition resulted in the disappearance of the hyperfine-shifted signal associated with a perdeuterated adamantane bound to CP450cam, while signals presumably associated with adamantane bound to other cavities persisted. We simulated the deuterium spinning side-band intensities for the enzyme-bound species using dipolar hyperfine coupling as the only anisotropic interaction; the deuterium quadrupolar interaction was apparently averaged due to a fast high-symmetry motion. These data provide direct support for previous proposals that substrates are conformationally mobile on the time scale of enzymatic turnover. The simulations suggested that the adamantane binds with an average metal-deuterium distance of 6.2 (+/-0.2) A, corresponding to a dipolar coupling constant of 6.5 (+/-0.5) kHz. PMID:10451377

  15. Molecular dynamics in paramagnetic materials as studied by magic-angle spinning 2H NMR spectra.

    PubMed

    Mizuno, Motohiro; Suzuki, You; Endo, Kazunaka; Murakami, Miwa; Tansho, Masataka; Shimizu, Tadashi

    2007-12-20

    A magic-angle spinning (MAS) 2H NMR experiment was applied to study the molecular motion in paramagnetic compounds. The temperature dependences of 2H MAS NMR spectra were measured for paramagnetic [M(H2O)6][SiF6] (M=Ni2+, Mn2+, Co2+) and diamagnetic [Zn(H2O)6][SiF6]. The paramagnetic compounds exhibited an asymmetric line shape in 2H MAS NMR spectra because of the electron-nuclear dipolar coupling. The drastic changes in the shape of spinning sideband patterns and in the line width of spinning sidebands due to the 180 degrees flip of water molecules and the reorientation of [M(H2O)6]2+ about its C3 axis were observed. In the paramagnetic compounds, paramagnetic spin-spin relaxation and anisotropic g-factor result in additional linebroadening of each of the spinning sidebands. The spectral simulation of MAS 2H NMR, including the effects of paramagnetic shift and anisotropic spin-spin relaxation due to electron-nuclear dipolar coupling and anisotropic g-factor, was performed for several molecular motions. Information about molecular motions in the dynamic range of 10(2) s(-1)

  16. High-resolution magic-angle spinning (13)C spectroscopy of brain tissue at natural abundance.

    PubMed

    Yang, Yongxia; Chen, Lei; Gao, Hongchang; Zeng, Danlin; Yue, Yong; Liu, Maili; Lei, Hao; Deng, Feng; Ye, Chaohui

    2006-03-01

    High-resolution magic-angle spinning (MAS) (1)H and (13)C magnetic resonance spectroscopy (MRS) has recently been applied to study the metabolism in intact biological tissue samples. Because of the low natural abundance and the low gyromagnetic ratio of the (13)C nuclei, signal enhancement techniques such as cross-polarization (CP) and distortionless enhancement by polarization transfer (DEPT) are often employed in MAS (13)C MRS to improve the detection sensitivity. In this study, several sensitivity enhancement techniques commonly used in liquid- and solid-state NMR, including CP, DEPT and nuclear Overhauser enhancement (NOE), were combined with MAS to acquire high-resolution (13)C spectra on intact rat brain tissue at natural abundance, and were compared for their performances. The results showed that different signal enhancement techniques are sensitive to different classes of molecules/metabolites, depending on their molecular weights and mobility. DEPT was found to enhance the signals of low-molecular weight metabolites exclusively, while the signals of lipids, which often are associated with membranes and have relatively lower mobility, were highly sensitive to CP enhancement. PMID:16477685

  17. Dynamic nuclear polarization at 40 kHz magic angle spinning.

    PubMed

    Chaudhari, Sachin R; Berruyer, Pierrick; Gajan, David; Reiter, Christian; Engelke, Frank; Silverio, Daniel L; Copéret, Christophe; Lelli, Moreno; Lesage, Anne; Emsley, Lyndon

    2016-04-21

    DNP-enhanced solid-state NMR spectroscopy under magic angle spinning (MAS) is rapidly developing into a powerful analytical tool to investigate the structure of a wide range of solid materials, because it provides unsurpassed sensitivity gains. Most developments and applications of DNP MAS NMR were so far reported at moderate spinning frequencies (up to 14 kHz using 3.2 mm rotors). Here, using a 1.3 mm MAS DNP probe operating at 18.8 T and ∼100 K, we show that signal amplification factors can be increased by up to a factor two when using smaller volume rotors as compared to 3.2 mm rotors, and report enhancements of around 60 over a range of sample spinning rates from 10 to 40 kHz. Spinning at 40 kHz is also shown to increase (29)Si coherence lifetimes by a factor three as compared to 10 kHz, substantially increasing sensitivity in CPMG type experiments. The contribution of quenching effects to the overall sensitivity gain at very fast MAS is evaluated, and applications are reported on a functionalised mesostructured organic-inorganic material. PMID:27035630

  18. Structure of a protein determined by solid-state magic-angle-spinning NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Castellani, Federica; van Rossum, Barth; Diehl, Annette; Schubert, Mario; Rehbein, Kristina; Oschkinat, Hartmut

    2002-11-01

    The determination of a representative set of protein structures is a chief aim in structural genomics. Solid-state NMR may have a crucial role in structural investigations of those proteins that do not easily form crystals or are not accessible to solution NMR, such as amyloid systems or membrane proteins. Here we present a protein structure determined by solid-state magic-angle-spinning (MAS) NMR. Almost complete 13C and 15N resonance assignments for a micro-crystalline preparation of the α-spectrin Src-homology 3 (SH3) domain formed the basis for the extraction of a set of distance restraints. These restraints were derived from proton-driven spin diffusion (PDSD) spectra of biosynthetically site-directed, labelled samples obtained from bacteria grown using [1,3-13C]glycerol or [2-13C]glycerol as carbon sources. This allowed the observation of long-range distance correlations up to ~7Å. The calculated global fold of the α-spectrin SH3 domain is based on 286 inter-residue 13C-13C and six 15N-15N restraints, all self-consistently obtained by solid-state MAS NMR. This MAS NMR procedure should be widely applicable to small membrane proteins that can be expressed in bacteria.

  19. Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization

    PubMed Central

    Barnes, Alexander B.; Mak-Jurkauskas, Melody L.; Matsuki, Yoh; Bajaj, Vikram S.; van der Wel, Patrick C. A.; DeRocher, Ronald; Bryant, Jeffrey; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Lugtenburg, Johan; Herzfeld, Judith; Griffin, Robert G.

    2009-01-01

    We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by improving long-term instrument stability. Changing samples in conventional cryogenic MAS DNP/NMR experiments involves warming the probe to room temperature, detaching all cryogenic, RF, and microwave connections, removing the probe from the magnet, replacing the sample, and reversing all the previous steps, with the entire cycle requiring a few hours. The sample exchange system described here — which relies on an eject pipe attached to the front of the MAS stator and a vacuum jacketed dewar with a bellowed hole — circumvents these procedures. To demonstrate the excellent sensitivity, resolution, and stability achieved with this quadruple resonance sample exchange probe, we have performed high precision distance measurements on the active site of the membrane protein bacteriorhodopsin. We also include a spectrum of the tripeptide N-f-MLF-OH at 100 K which shows 30 Hz linewidths. PMID:19356957

  20. Double-quantum homonuclear rotary resonance: Efficient dipolar recovery in magic-angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Nielsen, N. C.; Bildsøe, H.; Jakobsen, H. J.; Levitt, M. H.

    1994-08-01

    We describe an efficient method for the recovery of homonuclear dipole-dipole interactions in magic-angle spinning NMR. Double-quantum homonuclear rotary resonance (2Q-HORROR) is established by fulfilling the condition ωr=2ω1, where ωr is the sample rotation frequency and ω1 is the nutation frequency around an applied resonant radio frequency (rf) field. This resonance can be used for double-quantum filtering and measurement of homonuclear dipolar interactions in the presence of magic-angle spinning. The spin dynamics depend only weakly on crystallite orientation allowing good performance for powder samples. Chemical shift effects are suppressed to zeroth order. The method is demonstrated for singly and doubly 13C labeled L-alanine.

  1. Rotary resonance recoupling of 13C- 1H dipolar interactions in magic angle spinning 13C NMR of dynamic solids

    NASA Astrophysics Data System (ADS)

    Kitchin, Simon J.; Harris, Kenneth D. M.; Aliev, Abil E.; Apperley, David C.

    2000-06-01

    Rotary resonance recoupling of heteronuclear 13C- 1H dipolar interactions in magic angle spinning solid state 13C NMR spectra (recorded under conditions of 1H decoupling at frequency ν1 and magic angle spinning at frequency νr) has been studied for three examples of molecular solids (adamantane, ferrocene and hexamethylbenzene) in which substantial molecular motion is known to occur. It is shown that when rotary resonance conditions are satisfied (i.e. ν1/νr= n, for n=1 or 2), the recoupling can lead to motionally averaged Pake-like powder patterns from which information on 13C- 1H internuclear distances and/or molecular motion can be derived.

  2. Development of a magic-angle spinning nuclear magnetic resonance probe with a cryogenic detection system for sensitivity enhancement

    NASA Astrophysics Data System (ADS)

    Mizuno, Takashi; Hioka, Katsuya; Fujioka, Koji; Takegoshi, K.

    2008-04-01

    A novel nuclear magnetic resonance (NMR) probe for high-resolution solid-state NMR has been developed. In this probe, temperature of the detection coil is kept at cryogenic temperature (˜12K) for sensitivity enhancement, which is achieved not only by suppression of thermal noise but also by increment of a Q factor of the coil. A marked feature of this probe is that a sample rotating at magic angle is thermally isolated from the cryogenic system in order to realize high-resolution solid-state NMR measurement at various sample temperatures. We call this system as cryocoil magic-angle spinning (cryocoil MAS). H1 MAS NMR with the coil temperature of ˜20K was successfully observed for solid adamantane rotating at room temperature, and signal-to-noise increment due to this cryocoil approach was confirmed.

  3. High resolution structural characterization of Aβ42 amyloid fibrils by magic angle spinning NMR.

    PubMed

    Colvin, Michael T; Silvers, Robert; Frohm, Birgitta; Su, Yongchao; Linse, Sara; Griffin, Robert G

    2015-06-17

    The presence of amyloid plaques composed of amyloid beta (Aβ) fibrils is a hallmark of Alzheimer's disease (AD). The Aβ peptide is present as several length variants with two common alloforms consisting of 40 and 42 amino acids, denoted Aβ1-40 and Aβ1-42, respectively. While there have been numerous reports that structurally characterize fibrils of Aβ1-40, very little is known about the structure of amyloid fibrils of Aβ1-42, which are considered the more toxic alloform involved in AD. We have prepared isotopically (13)C/(15)N labeled AβM01-42 fibrils in vitro from recombinant protein and examined their (13)C-(13)C and (13)C-(15)N magic angle spinning (MAS) NMR spectra. In contrast to several other studies of Aβ fibrils, we observe spectra with excellent resolution and a single set of chemical shifts, suggesting the presence of a single fibril morphology. We report the initial structural characterization of AβM01-42 fibrils utilizing (13)C and (15)N shift assignments of 38 of the 43 residues, including the backbone and side chains, obtained through a series of cross-polarization based 2D and 3D (13)C-(13)C, (13)C-(15)N MAS NMR experiments for rigid residues along with J-based 2D TOBSY experiments for dynamic residues. We find that the first ∼5 residues are dynamic and most efficiently detected in a J-based TOBSY spectrum. In contrast, residues 16-42 are easily observed in cross-polarization experiments and most likely form the amyloid core. Calculation of ψ and φ dihedral angles from the chemical shift assignments indicate that 4 β-strands are present in the fibril's secondary structure. PMID:26001057

  4. High Resolution Structural Characterization of Aβ42 Amyloid Fibrils by Magic Angle Spinning NMR

    PubMed Central

    2015-01-01

    The presence of amyloid plaques composed of amyloid beta (Aβ) fibrils is a hallmark of Alzheimer’s disease (AD). The Aβ peptide is present as several length variants with two common alloforms consisting of 40 and 42 amino acids, denoted Aβ1–40 and Aβ1–42, respectively. While there have been numerous reports that structurally characterize fibrils of Aβ1–40, very little is known about the structure of amyloid fibrils of Aβ1–42, which are considered the more toxic alloform involved in AD. We have prepared isotopically 13C/15N labeled AβM01–42 fibrils in vitro from recombinant protein and examined their 13C–13C and 13C–15N magic angle spinning (MAS) NMR spectra. In contrast to several other studies of Aβ fibrils, we observe spectra with excellent resolution and a single set of chemical shifts, suggesting the presence of a single fibril morphology. We report the initial structural characterization of AβM01–42 fibrils utilizing 13C and 15N shift assignments of 38 of the 43 residues, including the backbone and side chains, obtained through a series of cross-polarization based 2D and 3D 13C–13C, 13C–15N MAS NMR experiments for rigid residues along with J-based 2D TOBSY experiments for dynamic residues. We find that the first ∼5 residues are dynamic and most efficiently detected in a J-based TOBSY spectrum. In contrast, residues 16–42 are easily observed in cross-polarization experiments and most likely form the amyloid core. Calculation of ψ and φ dihedral angles from the chemical shift assignments indicate that 4 β-strands are present in the fibril’s secondary structure. PMID:26001057

  5. High zenith angle observations of PKS 2155-304 with the MAGIC-I telescope

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Braun, I.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido, D.; Giavitto, G.; Godinović, N.; Gozzini, S. R.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López, R.; López-Oramas, A.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Niedzwiecki, A.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Paneque, D.; Paoletti, R.; Pardo, S.; Paredes, J. M.; Partini, S.; Perez-Torres, M. A.; Persic, M.; Peruzzo, L.; Pilia, M.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puerto Gimenez, I.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Treves, A.; Uellenbeck, M.; Vankov, H.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.

    2012-08-01

    Context. The high frequency peaked BL Lac PKS 2155-304 with a redshift of z = 0.116 was discovered in 1997 in the very high energy (VHE, E > 100 GeV) γ-ray range by the University of Durham Mark VI γ-ray Cherenkov telescope in Australia with a flux corresponding to 20% of the Crab Nebula flux. It was later observed and detected with high significance by the southern Cherenkov observatory H.E.S.S. establishing this source as the best studied southern TeV blazar. Detection from the northern hemisphere is difficult due to challenging observation conditions under large zenith angles. In July 2006, the H.E.S.S. collaboration reported an extraordinary outburst of VHE γ-emission. During the outburst, the VHE γ-ray emission was found to be variable on the time scales of minutes and with a mean flux of ~7 times the flux observed from the Crab Nebula. Follow-up observations with the MAGIC-I standalone Cherenkov telescope were triggered by this extraordinary outburst and PKS 2155-304 was observed between 28 July to 2 August 2006 for 15 h at large zenith angles. Aims: We studied the behavior of the source after its extraordinary flare. Furthermore, we developed an analysis method in order to analyze these data taken under large zenith angles. Methods: Here we present an enhanced analysis method for data taken at high zenith angles. We developed improved methods for event selection that led to a better background suppression. Results: The quality of the results presented here is superior to the results presented previously for this data set: detection of the source on a higher significance level and a lower analysis threshold. The averaged energy spectrum we derived has a spectral index of (-3.5 ± 0.2) above 400 GeV, which is in good agreement with the spectral shape measured by H.E.S.S. during the major flare on MJD 53 944. Furthermore, we present the spectral energy distribution modeling of PKS 2155-304. With our observations we increased the duty cycle of the source

  6. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe

    NASA Astrophysics Data System (ADS)

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-05-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B 1 S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B 1 S field is 13 μT/W 1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γSB 1 S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement ( ɛ) vs. ω1 S/(2 π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment.

  7. Tailored low-power cross-polarization under fast magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Demers, Jean-Philippe; Vijayan, Vinesh; Becker, Stefan; Lange, Adam

    2010-08-01

    High static magnetic fields and very fast magic-angle spinning (MAS) promise to improve resolution and sensitivity of solid-state NMR experiments. The fast MAS regime has permitted the development of low-power cross-polarization schemes, such as second-order cross-polarization (SOCP), which prevent heat deposition in the sample. Those schemes are however limited in bandwidth, as weak radio-frequency (RF) fields only cover a small chemical shift range for rare nuclei (e.g. 13C). Another consideration is that the efficiency of cross-polarization is very sensitive to magnetization decay that occurs during the spin-lock pulse on the abundant nuclei (e.g. 1H). Having characterized this decay in glutamine at 60 kHz MAS, we propose two complementary strategies to tailor cross-polarization to desired spectral regions at low RF power. In the case of multiple sites with small chemical shift dispersion, a larger bandwidth for SOCP is obtained by slightly increasing the RF power while avoiding recoupling conditions that lead to fast spin-lock decay. In the case of two spectral regions with large chemical shift offset, an extension of the existing low-power schemes, called MOD-CP, is introduced. It consists of a spin-lock on 1H and an amplitude-modulated spin-lock on the rare nucleus. The range of excited chemical shifts is assessed by experimental excitation profiles and numerical simulation of an I 2S spin system. All SOCP-based schemes exhibit higher sensitivity than high-power CP schemes, as demonstrated on solid (glutamine) and semi-solid (hydrated, micro-crystalline ubiquitin) samples.

  8. Correlating high-resolution magic angle spinning NMR spectroscopy and gene analysis in osteoarthritic cartilage.

    PubMed

    Tufts, Lauren; Shet Vishnudas, Keerthi; Fu, Eunice; Kurhanewicz, John; Ries, Michael; Alliston, Tamara; Li, Xiaojuan

    2015-05-01

    Osteoarthritis (OA) is a common multifactorial and heterogeneous degenerative joint disease, and biochemical changes in cartilage matrix occur during the early stages of OA before morphological changes occur. Thus, it is desired to measure regional biochemical changes in the joint. High-resolution magic angle spinning (HRMAS) NMR spectroscopy is a powerful method of observing cartilaginous biochemical changes ex vivo, including the concentrations of alanine and N-acetyl, which are markers of collagen and total proteoglycan content, respectively. Previous studies have observed significant changes in chondrocyte metabolism of OA cartilage via the altered gene expression profiles of ACAN, COL2A1 and MMP13, which encode aggrecan, type II collagen and matrix metalloproteinase 13 (a protein crucial in the degradation of type II collagen), respectively. Employing HRMAS, this study aimed to elucidate potential relationships between N-acetyl and/or alanine and ACAN, COL2A1 and/or MMP13 expression profiles in OA cartilage. Thirty samples from the condyles of five subjects undergoing total knee arthroplasty to treat OA were collected. HRMAS spectra were obtained at 11.7 T for each sample. RNA was subsequently extracted to determine gene expression profiles. A significant negative correlation between N-acetyl metabolite and ACAN gene expression levels was observed; this provides further evidence of N-acetyl as a biomarker of cartilage degeneration. The alanine doublet was distinguished in the spectra of 15 of the 30 specimens of this study. Alanine can only be detected with HRMAS NMR spectroscopy when the collagen framework has been degraded such that alanine is sufficiently mobile to form a distinguished peak in the spectrum. Thus, HRMAS NMR spectroscopy may provide unique localized measurements of collagenous degeneration in OA cartilage. The identification of imaging markers that could provide a link between OA pathology and chondrocyte metabolism will facilitate the

  9. Spinning-sideband patterns in multiple-quantum magic-angle spinning NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Friedrich, Ulli

    1998-12-01

    Recent interest has focused on solid-state NMR experiments which excite multiple-quantum (MQ) coherences in the presence of magic-angle spinning (MAS). Such experiments have been applied to both dipolar-coupled spin Ι = 1/2 and half-integer quadrupolar systems. A feature common to both cases is the observation of interesting spinning sideband patterns in the indirect (MQ) dimension. In this paper, the origin of these patterns is reviewed in terms of two distinct mechanisms: first, rotor encoding of the dipolar or quadrupolar interaction caused by the change in the Hamiltonian active during the MQ reconversion period relative to the excitation period (reconversion rotor encoding, RRE); and, second, rotor modulation of the interaction during the evolution of the MQ coherences in the t1 dimension (evolution rotor modulation, ERM). Only the first mechanism is present for total spin coherences, while for lower-order MQ coherences both mechanisms contribute to the pattern. For dipolar and quadrupolar model systems, i.e., the three protons of a methyl group and quadrupolar nuclei with spin Ι = 3/2 and Ι = 5/2 and axially symmetric first-order quadrupolar interactions, analytical expressions are derived for all orders of MQ MAS signals. Simulations based on these analytical expressions and numerical density matrix simulations are compared with experimental spectra. Additional perturbing influences, such as the heteronuclear dipolar coupling between a quadrupolar and a spin Ι = 1/2 nucleus, are taken into account. The effect of dipolar couplings on a quadrupolar MQ spectrum is found to be enhanced by the order of the observed MQ coherence.

  10. Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance

    SciTech Connect

    Turcu, Romulus V.F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Z.

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 deg C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  11. Rotor design for high pressure magic angle spinning nuclear magnetic resonance.

    PubMed

    Turcu, Romulus V F; Hoyt, David W; Rosso, Kevin M; Sears, Jesse A; Loring, John S; Felmy, Andrew R; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low (1)H and (13)C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe(2+))(3)Si(2)O(5)(OH)(4)), in contact with liquid water in water-saturated supercritical CO(2) (scCO(2)) at 150 bar and 50°C. This mineral is relevant to the deep geologic disposal of CO(2), but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields. PMID:23220181

  12. Rotor design for high pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Turcu, Romulus V. F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 °C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  13. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe.

    PubMed

    Nanni, Emilio A; Barnes, Alexander B; Matsuki, Yoh; Woskov, Paul P; Corzilius, Björn; Griffin, Robert G; Temkin, Richard J

    2011-05-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B(1S)) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4mm diameter sapphire rotor containing the sample. The predicted average B(1S) field is 13μT/W(1/2), where S denotes the electron spin. For a routinely achievable input power of 5W the corresponding value is γ(S)B(1S)=0.84MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω(1S)/(2π) for a sample of (13)C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  14. Intermolecular structure determination of amyloid fibrils with magic-angle spinning and dynamic nuclear polarization NMR

    PubMed Central

    Bayro, Marvin J.; Debelouchina, Galia T.; Eddy, Matthew T.; Birkett, Neil R.; MacPhee, Catherine E.; Rosay, Melanie; Maas, Werner E.; Dobson, Christopher M.

    2011-01-01

    We describe magic-angle spinning NMR experiments designed to elucidate the interstrand architecture of amyloid fibrils. Three methods are introduced for this purpose, two being based on the analysis of long-range 13C-13C correlation spectra and a third based on the identification of intermolecular interactions in 13C-15N spectra. We show, in studies of fibrils formed by the 86-residue SH3 domain of PI3 kinase (PI3-SH3), that efficient 13C-13C correlation spectra display a resonance degeneracy that establishes a parallel, in-register alignment of the proteins in the amyloid fibrils. In addition, this degeneracy can be circumvented to yield direct intermolecular constraints. The 13C-13C experiments are corroborated by 15N-13C correlation spectrum obtained from a mixed [15N,12C]/[14N,13C] sample which directly quantifies interstrand distances. Furthermore, when the spectra are recorded with signal enhancement provided by dynamic nuclear polarization (DNP) at 100 K, we demonstrate a dramatic increase (from 23 to 52) in the number of intermolecular 15N-13C constraints present in the spectra. The increase in the information content is due to the enhanced signal intensities and to the fact that dynamic processes, leading to spectral intensity losses, are quenched at low temperatures. Thus, acquisition of low temperature spectra addresses a problem that is frequently encountered in MAS spectra of proteins. In total the experiments provide 111 intermolecular 13C-13C and 15N-13C constraints that establish that the PI3-SH3 protein strands are aligned in a parallel, in-register arrangement within the amyloid fibril. PMID:21774549

  15. Microwave Field Distribution in a Magic Angle Spinning Dynamic Nuclear Polarization NMR Probe

    PubMed Central

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-01-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13µT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γ SB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ε) vs. ω1S/(2π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  16. Nuclear depolarization and absolute sensitivity in magic-angle spinning cross effect dynamic nuclear polarization.

    PubMed

    Mentink-Vigier, Frédéric; Paul, Subhradip; Lee, Daniel; Feintuch, Akiva; Hediger, Sabine; Vega, Shimon; De Paëpe, Gaël

    2015-09-14

    Over the last two decades solid state Nuclear Magnetic Resonance has witnessed a breakthrough in increasing the nuclear polarization, and thus experimental sensitivity, with the advent of Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). To enhance the nuclear polarization of protons, exogenous nitroxide biradicals such as TOTAPOL or AMUPOL are routinely used. Their efficiency is usually assessed as the ratio between the NMR signal intensity in the presence and the absence of microwave irradiation εon/off. While TOTAPOL delivers an enhancement εon/off of about 60 on a model sample, the more recent AMUPOL is more efficient: >200 at 100 K. Such a comparison is valid as long as the signal measured in the absence of microwaves is merely the Boltzmann polarization and is not affected by the spinning of the sample. However, recent MAS-DNP studies at 25 K by Thurber and Tycko (2014) have demonstrated that the presence of nitroxide biradicals combined with sample spinning can lead to a depolarized nuclear state, below the Boltzmann polarization. In this work we demonstrate that TOTAPOL and AMUPOL both lead to observable depolarization at ≈110 K, and that the magnitude of this depolarization is radical dependent. Compared to the static sample, TOTAPOL and AMUPOL lead, respectively, to nuclear polarization losses of up to 20% and 60% at a 10 kHz MAS frequency, while Trityl OX63 does not depolarize at all. This experimental work is analyzed using a theoretical model that explains how the depolarization process works under MAS and gives new insights into the DNP mechanism and into the spin parameters, which are relevant for the efficiency of a biradical. In light of these results, the outstanding performance of AMUPOL must be revised and we propose a new method to assess the polarization gain for future radicals. PMID:26235749

  17. Solid-state 19F-NMR analysis of 19F-labeled tryptophan in gramicidin A in oriented membranes.

    PubMed Central

    Grage, Stephan L; Wang, Junfeng; Cross, Timothy A; Ulrich, Anne S

    2002-01-01

    The response of membrane-associated peptides toward the lipid environment or other binding partners can be monitored by solid-state NMR of suitably labeled side chains. Tryptophan is a prominent amino acid in transmembrane helices, and its (19)F-labeled analogues are generally biocompatible and cause little structural perturbation. Hence, we use 5F-Trp as a highly sensitive NMR probe to monitor the conformation and dynamics of the indole ring. To establish this (19)F-NMR strategy, gramicidin A was labeled with 5F-Trp in position 13 or 15, whose chi(1)/chi(2) torsion angles are known from previous (2)H-NMR studies. First, the alignment of the (19)F chemical shift anisotropy tensor within the membrane was deduced by lineshape analysis of oriented samples. Next, the three principal axes of the (19)F chemical shift anisotropy tensor were assigned within the molecular frame of the indole ring. Finally, determination of chi(1)/chi(2) for 5F-Trp in the lipid gel phase showed that the side chain alignment differs by up to 20 degrees from its known conformation in the liquid crystalline state. The sensitivity gain of (19)F-NMR and the reduction in the amount of material was at least 10-fold compared with previous (2)H-NMR studies on the same system and 100-fold compared with (15)N-NMR. PMID:12496101

  18. Solid-state {sup 17}O magic-angle and dynamic-angle spinning NMR study of the SiO{sub 2} polymorph coesite

    SciTech Connect

    Grandinetti, P.J.; Baltisberger, J.H.; Farnan, I.; Stebbins, J.F.; Werner, U.; Pines, A. |

    1995-08-10

    Five distinctly resolved {sup 17}O solid-state NMR resonances in room temperature coesite, an SiO{sub 2} polymorph, have been observed and assigned using dynamic angle spinning (DAS) at 11.7 T along with magic angle spinning (MAS) spectra at 9.4 and 11.7 T. The {sup 17}O quadrupolar parameters for each of the five oxygen environments in coesite are correlated with the Si-O-Si bridging bond angles determined by diffraction experiments. The sign of e{sup 2}-qQ/h along with the orientation of the electric field gradient for oxygen in the Si-O-Si linkage were determined from a Townes-Dailey analysis of the data. 41 refs., 7 figs., 5 tabs.

  19. Characterization of lithium coordination sites with magic-angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Haimovich, A.; Goldbourt, A.

    2015-05-01

    Lithium, in the form of lithium carbonate, is one of the most common drugs for bipolar disorder. Lithium is also considered to have an effect on many other cellular processes hence it possesses additional therapeutic as well as side effects. In order to quantitatively characterize the binding mode of lithium, it is required to identify the interacting species and measure their distances from the metal center. Here we use magic-angle spinning (MAS) solid-state NMR to study the binding site of lithium in complex with glycine and water (LiGlyW). Such a compound is a good enzyme mimetic since lithium is four-coordinated to one water molecule and three carboxylic groups. Distance measurements to carbons are performed using a 2D transferred echo double resonance (TEDOR) MAS solid-state NMR experiment, and water binding is probed by heteronuclear high-resolution proton-lithium and proton-carbon correlation (wPMLG-HETCOR) experiments. Both HETCOR experiments separate the main complex from impurities and non-specifically bound lithium species, demonstrating the sensitivity of the method to probe the species in the binding site. Optimizations of the TEDOR pulse scheme in the case of a quadrupolar nucleus with a small quadrupole coupling constant show that it is most efficient when pulses are positioned on the spin-1/2 (carbon-13) nucleus. Since the intensity of the TEDOR signal is not normalized, careful data analysis that considers both intensity and dipolar oscillations has to be performed. Nevertheless we show that accurate distances can be extracted for both carbons of the bound glycine and that these distances are consistent with the X-ray data and with lithium in a tetrahedral environment. The lithium environment in the complex is very similar to the binding site in inositol monophosphatase, an enzyme associated with bipolar disorder and the putative target for lithium therapy. A 2D TEDOR experiment applied to the bacterial SuhB gene product of this enzyme was designed

  20. High Resolution Magic Angle Spinning 1H-NMR Metabolic Profiling of Nanoliter Biological Tissues at High Magnetic Field

    SciTech Connect

    Feng, Ju; Hu, Jian Z.; Burton, Sarah D.; Hoyt, David W.

    2013-03-05

    It is demonstrated that a high resolution magic angle spinning 1H-NMR spectrum of biological tissue samples with volumes as small as 150 nanoliters, or 0.15 mg in weight, can be acquired in a few minutes at 21.1 T magnetic field using a commercial 1.6 mm fast-MAS probe with minor modification of the MAS rotor. The strategies of sealing the samples inside the MAS rotor to avoid fluid leakage as well as the ways of optimizing the signal to noise are discussed.

  1. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    DOEpatents

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  2. CHARACTERIZATION OF TANK 19F SAMPLES

    SciTech Connect

    Oji, L.; Diprete, D.; Click, D.

    2009-12-17

    The Savannah River National Laboratory (SRNL) was asked by Liquid Waste Operations to characterize Tank 19F closure samples. Tank 19F slurry samples analyzed included the liquid and solid fractions derived from the slurry materials along with the floor scrape bottom Tank 19F wet solids. These samples were taken from Tank 19F in April 2009 and made available to SRNL in the same month. Because of limited amounts of solids observed in Tank 19F samples, the samples from the north quadrants of the tank were combined into one Tank 19F North Hemisphere sample and similarly the south quadrant samples were combined into one Tank 19F South Hemisphere sample. These samples were delivered to the SRNL shielded cell. The Tank 19F samples were analyzed for radiological, chemical and elemental components. Where analytical methods yielded additional contaminants other than those requested by the customer, these results were also reported. The target detection limits for isotopes analyzed were based on detection values of 1E-04 {micro}Ci/g for most radionuclides and customer desired detection values of 1E-05 {micro}Ci/g for I-129, Pa-231, Np-237, and Ra-226. While many of the target detection limits, as specified in the technical task request and task technical and quality assurance plans were met for the species characterized for Tank 19F, some were not met. In a number of cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. SRNL, in conjunction with the plant customer, reviewed all these cases and determined that the impacts were negligible.

  3. Lipid bilayer preparations of membrane proteins for oriented and magic-angle spinning solid-state NMR samples

    PubMed Central

    Das, Nabanita; Murray, Dylan T; Cross, Timothy A

    2014-01-01

    Solid-state NMR spectroscopy has been used successfully for characterizing the structure and dynamics of membrane proteins as well as their interactions with other proteins in lipid bilayers. such an environment is often necessary for achieving native-like structures. sample preparation is the key to this success. Here we present a detailed description of a robust protocol that results in high-quality membrane protein samples for both magic-angle spinning and oriented-sample solid-state NMR. the procedure is demonstrated using two proteins: CrgA (two transmembrane helices) and rv1861 (three transmembrane helices), both from Mycobacterium tuberculosis. the success of this procedure relies on two points. First, for samples for both types of NMR experiment, the reconstitution of the protein from a detergent environment to an environment in which it is incorporated into liposomes results in ‘complete’ removal of detergent. second, for the oriented samples, proper dehydration followed by rehydration of the proteoliposomes is essential. By using this protocol, proteoliposome samples for magic-angle spinning NMR and uniformly aligned samples (orientational mosaicity of <1°) for oriented-sample NMR can be obtained within 10 d. PMID:24157546

  4. Floquet-Magnus expansion for general N-coupled spins systems in magic-angle spinning nuclear magnetic resonance spectra

    NASA Astrophysics Data System (ADS)

    Mananga, Eugene Stephane; Charpentier, Thibault

    2015-04-01

    In this paper we present a theoretical perturbative approach for describing the NMR spectrum of strongly dipolar-coupled spin systems under fast magic-angle spinning. Our treatment is based on two approaches: the Floquet approach and the Floquet-Magnus expansion. The Floquet approach is well known in the NMR community as a perturbative approach to get analytical approximations. Numerical procedures are based on step-by-step numerical integration of the corresponding differential equations. The Floquet-Magnus expansion is a perturbative approach of the Floquet theory. Furthermore, we address the " γ -encoding" effect using the Floquet-Magnus expansion approach. We show that the average over " γ " angle can be performed for any Hamiltonian with γ symmetry.

  5. Magic-angle-spinning NMR of the drug resistant S31N M2 proton transporter from influenza A.

    PubMed

    Andreas, Loren B; Eddy, Matthew T; Chou, James J; Griffin, Robert G

    2012-05-01

    We report chemical shift assignments of the drug-resistant S31N mutant of M2(18-60) determined using 3D magic-angle-spinning (MAS) NMR spectra acquired with a (15)N-(13)C ZF-TEDOR transfer followed by (13)C-(13)C mixing by RFDR. The MAS spectra reveal two sets of resonances, indicating that the tetramer assembles as a dimer of dimers, similar to the wild-type channel. Helicies from the two sets of chemical shifts are shown to be in close proximity at residue H37, and the assignments reveal a difference in the helix torsion angles, as predicted by TALOS+, for the key resistance residue N31. In contrast to wild-type M2(18-60), chemical shift changes are minimal upon addition of the inhibitor rimantadine, suggesting that the drug does not bind to S31N M2. PMID:22480220

  6. SCAM-STMAS: satellite-transition MAS NMR of quadrupolar nuclei with self-compensation for magic-angle misset

    NASA Astrophysics Data System (ADS)

    Ashbrook, Sharon E.; Wimperis, Stephen

    2003-06-01

    Several methods are available for the acquisition of high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer spin quantum number. Satellite-transition MAS (STMAS) offers an approach that employs only conventional MAS hardware and can yield substantial signal enhancements over the widely used multiple-quantum MAS (MQMAS) experiment. However, the presence of the first-order quadrupolar interaction in the satellite transitions imposes the requirement of a high degree of accuracy in the setting of the magic angle on the NMR probehead. The first-order quadrupolar interaction is only fully removed if the sample spinning angle, χ, equals cos-1(1/ 3) exactly and rotor synchronization is performed. The required level of accuracy is difficult to achieve experimentally, particularly when the quadrupolar interaction is large. If the magic angle is not set correctly, the first-order splitting is reintroduced and the spectral resolution is severely compromised. Recently, we have demonstrated a novel STMAS method (SCAM-STMAS) that is self-compensated for angle missets of up to ±1° via coherence transfer between the two different satellite transitions ST +( mI=+3/2↔+1/2) and ST -( mI=-1/2↔-3/2) midway through the t1 period. In this work we describe in more detail the implementation of SCAM-STMAS and demonstrate its wider utility through 23Na ( I=3/2), 87Rb ( I=3/2), 27Al ( I=5/2), and 59Co ( I=7/2) NMR. We discuss linewidths in SCAM-STMAS and the limits over which angle-misset compensation is achieved and we demonstrate that SCAM-STMAS is more tolerant of temporary spinning rate fluctuations than STMAS, resulting in less " t1 noise" in the two-dimensional spectrum. In addition, alternative correlation experiments, for example involving the use of double-quantum coherences, that similarly display self-compensation for angle misset are investigated. The use of SCAM-STMAS is also considered in systems where other high-order interactions, such as third

  7. Indirectly detected chemical shift correlation NMR spectroscopy in solids under fast magic angle spinning

    SciTech Connect

    Mao, Kanmi

    2011-01-01

    The development of fast magic angle spinning (MAS) opened up an opportunity for the indirect detection of insensitive low-γ nuclei (e.g., 13C and 15N) via the sensitive high-{gamma} nuclei (e.g., 1H and 19F) in solid-state NMR, with advanced sensitivity and resolution. In this thesis, new methodology utilizing fast MAS is presented, including through-bond indirectly detected heteronuclear correlation (HETCOR) spectroscopy, which is assisted by multiple RF pulse sequences for 1H-1H homonuclear decoupling. Also presented is a simple new strategy for optimization of 1H-1H homonuclear decoupling. As applications, various classes of materials, such as catalytic nanoscale materials, biomolecules, and organic complexes, are studied by combining indirect detection and other one-dimensional (1D) and two-dimensional (2D) NMR techniques. Indirectly detected through-bond HETCOR spectroscopy utilizing refocused INEPT (INEPTR) mixing was developed under fast MAS (Chapter 2). The time performance of this approach in 1H detected 2D 1H{l_brace}13C{r_brace} spectra was significantly improved, by a factor of almost 10, compared to the traditional 13C detected experiments, as demonstrated by measuring naturally abundant organic-inorganic mesoporous hybrid materials. The through-bond scheme was demonstrated as a new analytical tool, which provides complementary structural information in solid-state systems in addition to through-space correlation. To further benefit the sensitivity of the INEPT transfer in rigid solids, the combined rotation and multiple-pulse spectroscopy (CRAMPS) was implemented for homonuclear 1H decoupling under fast MAS (Chapter 3). Several decoupling schemes (PMLG5m$\\bar{x}$, PMLG5mm$\\bar{x}$x and SAM3) were analyzed to maximize the performance of through-bond transfer based

  8. Permanent magnet assembly producing a strong tilted homogeneous magnetic field: towards magic angle field spinning NMR and MRI.

    PubMed

    Sakellariou, Dimitris; Hugon, Cédric; Guiga, Angelo; Aubert, Guy; Cazaux, Sandrine; Hardy, Philippe

    2010-12-01

    We introduce a cylindrical permanent magnet design that generates a homogeneous and strong magnetic field having an arbitrary inclination with respect to the axis of the cylinder. The analytical theory of 3 D magnetostatics has been applied to this problem, and a hybrid magnet structure has been designed. This structure contains two magnets producing a longitudinal and transverse component for the magnetic field, whose amplitudes and homogeneities can be fully controlled by design. A simple prototype has been constructed using inexpensive small cube magnets, and its magnetic field has been mapped using Hall and NMR probe sensors. This magnet can, in principle, be used for magic angle field spinning NMR and MRI experiments allowing for metabolic chemical shift profiling in small living animals. PMID:20891027

  9. Nondestructive high-resolution solid-state NMR of rotating thin films at the magic-angle.

    PubMed

    Inukai, Munehiro; Noda, Yasuto; Takeda, Kazuyuki

    2011-12-01

    We present a new approach to nondestructive magic-angle spinning (MAS) nuclear magnetic resonance (NMR) for thin films. In this scheme, the sample put on the top of a rotor is spun using the conventional MAS system, and the NMR signals are detected with an additional coil. Stable spinning of disk-shaped samples with diameters of 7 mm and 12 mm at 14.2 and 7 kHz are feasible. We present 7Li MAS NMR experiments of a thin-film sample of LiCoO2 with a thickness of 200 nm. Taking advantage of the nondestructive feature of the experiment, we also demonstrate ex situ experiments, by tracing conformation change upon annealing for various durations. This approach opens the door for in situ MAS NMR of thin-film devices as well. PMID:21958755

  10. Magic angle spinning NMR investigation of influenza A M2(18-60): support for an allosteric mechanism of inhibition.

    PubMed

    Andreas, Loren B; Eddy, Matthew T; Pielak, Rafal M; Chou, James; Griffin, Robert G

    2010-08-18

    The tetrameric M2 proton channel from influenza A virus conducts protons at low pH and is inhibited by aminoadamantyl drugs such as amantadine and rimantadine (Rmt). We report magic angle spinning NMR spectra of POPC and DPhPC membrane-embedded M2(18-60), both apo and in the presence of Rmt. Similar line widths in the spectra of apo and bound M2 indicate that Rmt does not have a significant impact on the dynamics or conformational heterogeneity of this construct. Substantial chemical shift changes for many residues in the transmembrane region support an allosteric mechanism of inhibition. An Rmt titration supports a binding stoichiometry of >1 Rmt molecule per channel and shows that nonspecific binding or changes in membrane composition are unlikely sources of the chemical shift changes. In addition, doubling of spectral lines in all of the observed samples provides evidence that the channel assembles with twofold symmetry. PMID:20698642

  11. Nondestructive high-resolution solid-state NMR of rotating thin films at the magic-angle

    NASA Astrophysics Data System (ADS)

    Inukai, Munehiro; Noda, Yasuto; Takeda, Kazuyuki

    2011-12-01

    We present a new approach to nondestructive magic-angle spinning (MAS) nuclear magnetic resonance (NMR) for thin films. In this scheme, the sample put on the top of a rotor is spun using the conventional MAS system, and the NMR signals are detected with an additional coil. Stable spinning of disk-shaped samples with diameters of 7 mm and 12 mm at 14.2 and 7 kHz are feasible. We present 7Li MAS NMR experiments of a thin-film sample of LiCoO 2 with a thickness of 200 nm. Taking advantage of the nondestructive feature of the experiment, we also demonstrate ex situ experiments, by tracing conformation change upon annealing for various durations. This approach opens the door for in situ MAS NMR of thin-film devices as well.

  12. Experimental study of resolution of proton chemical shifts in solids: Combined multiple pulse NMR and magic-angle spinning

    SciTech Connect

    Ryan, L.M.; Taylor, R.E.; Paff, A.J.; Gerstein, B.C.

    1980-01-01

    High-resolution nuclear magnetic resonance spectra of protons in rigid, randomly oriented solids have been measured using combined homonuclear dipolar decoupling (via multiple pulse techniques) and attenuation of chemical shift anisotropies (via magic-angle sample spinning). Under those conditions, isotropic proton chemical shifts were recorded for a variety of chemical species, with individual linewidths varying from about 55 to 110 Hz (1--2 ppm). Residual line broadening was due predominately to (i) magnetic-field instability and inhomogeneity, (ii) unresolved proton--proton spin couplings, (iii) chemical shift dispersion, (iv) residual dipolar broadening, and (v) lifetime broadening under the multiple pulse sequences used. The magnitudes of those effects and the current limits of resolution for this experiment in our spectrometer have been investigated. The compounds studied included organic solids (4, 4'-dimethylbenzophenone, 2, 6-dimethylbenzoic acid, and aspirin), polymers (polystyrene and polymethylmethacrylate), and the vitrain portion of a bituminous coal.

  13. Two-dimensional (13)C-(13)C correlation spectroscopy with magic angle spinning and dynamic nuclear polarization.

    PubMed

    Rosay, Melanie; Weis, Volker; Kreischer, Kenneth E; Temkin, Richard J; Griffin, Robert G

    2002-04-01

    The sensitivity of solid-state NMR experiments can be enhanced with dynamic nuclear polarization (DNP), a technique that transfers the high Boltzmann polarization of unpaired electrons to nuclei. Signal enhancements of up to 23 have been obtained for magic angle spinning (MAS) experiments at 5 T and 85-90 K using a custom-designed high-power gyrotron. The extended stability of MAS/DNP experiments at low temperature is demonstrated with (1)H-driven (13)C spin-diffusion experiments on the amino acid proline. These (13)C-(13)C chemical shift correlation spectra are the first two-dimensional MAS/DNP experiments performed at high field (>1.4 T). PMID:11916398

  14. Molecular orientational dynamics in solid C70: Investigation by one- and two-dimensional magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Tycko, R.; Dabbagh, G.; Vaughan, G. B. M.; Heiney, P. A.; Strongin, R. M.; Cichy, M. A.; Smith, A. B., III

    1993-11-01

    We present the results of 13C nuclear magnetic resonance (NMR) measurements that probe molecular orientational dynamics in solid C70 in the temperature range 223-343 K. Orientational dynamics affect the NMR line shapes and spin-lattice relaxation rates by modulating the 13C chemical shift anisotropy (CSA). Motionally averaged CSA line shapes, determined from both one-dimensional and two-dimensional magic angle spinning NMR spectra, and relaxation rates are determined for each of the five inequivalent carbon sites in the C70 molecule. Comparisons of the results for the five sites provide evidence for rapid uniaxial molecular reorientation in the monoclinic (T≤280 K) and rhombohedral (280≤T≤330 K) phases and rapid isotropic reorientation in the face-centered cubic (T≥330 K) phase. The orientational correlation time is roughly 2 ns at 250 K and of the order of 5 ps at 340 K.

  15. Biochemical classification of kidney carcinoma biopsy samples using magic-angle-spinning 1H nuclear magnetic resonance spectroscopy.

    PubMed

    Moka, D; Vorreuther, R; Schicha, H; Spraul, M; Humpfer, E; Lipinski, M; Foxall, P J; Nicholson, J K; Lindon, J C

    1998-05-01

    High resolution 1H nuclear magnetic resonance (NMR) spectra using spinning at the magic angle (1H MAS NMR) have been obtained on intact normal and pathological kidney tissue samples from patients undergoing surgery for renal cell carcinoma (RCC). The spectra were measured on ca. 80 mg samples and provided high resolution 1H NMR spectra in which effects of dipolar couplings, chemical shift anisotropy and magnetic susceptibility differences are minimised thus yielding high spectral resolution. Conventional one-dimensional and spin-echo spectra and two-dimensional J-resolved, TOCSY and 1H-13C HMQC spectra were also measured on selected samples and these allowed the assignment of resonances of endogenous substances comprising both cytosolic and membrane components. The tumour tissues were characterised principally by an increased lipid content. These are the first reported results on human tumour tissues using this technique and the approach offers potential for the rapid classification of different types of tumour tissue. PMID:9608434

  16. Resonance Assignments and Secondary Structure Analysis of Dynein Light Chain 8 by Magic-angle Spinning NMR Spectroscopy

    SciTech Connect

    Sun, Shangjin; Butterworth, Andrew H.; Paramasivam, Sivakumar; Yan, Si; Lightcap, Christine M.; Williams, John C.; Polenova, Tatyana E.

    2011-08-04

    Dynein light chain LC8 is the smallest subunit of the dynein motor complex and has been shown to play important roles in both dynein-dependent and dynein-independent physiological functions via its interaction with a number of its binding partners. It has also been linked to pathogenesis including roles in viral infections and tumorigenesis. Structural information for LC8-target proteins is critical to understanding the underlying function of LC8 in these complexes. However, some LC8-target interactions are not amenable to structural characterization by conventional structural biology techniques owing to their large size, low solubility, and crystallization difficulties. Here, we report magic-angle spinning (MAS) NMR studies of the homodimeric apo-LC8 protein as a first effort in addressing more complex, multi-partner, LC8-based protein assemblies. We have established site-specific backbone and side-chain resonance assignments for the majority of the residues of LC8, and show TALOS+-predicted torsion angles ø and ψ in close agreement with most residues in the published LC8 crystal structure. Data obtained through these studies will provide the first step toward using MAS NMR to examine the LC8 structure, which will eventually be used to investigate protein–protein interactions in larger systems that cannot be determined by conventional structural studies.

  17. Photoneutron angular distribution of 19F

    NASA Astrophysics Data System (ADS)

    Kuo, P. C.-K.; Jury, J. W.; McNeill, K. G.; Sherman, N. K.; Davidson, W. F.

    1989-07-01

    Photoneutron time-of-flight spectra from the reaction 19F(γ, n 0) 18F were measured between 48° and 139° using 10 m flight paths over the excitation energy range from 15-25 MeV. The measured values of the normalized Legendre a1 and a3 coefficients are very small or close to zero over the energy region studied, indicating dominance of E1 absorption in this region. A simple modeldependent analysis of the a2 coefficient showed that the likely reaction mechanisms are mainly s → p and d → p single-particle transitions of channel spin {1}/{2}. A comparison of the present angleintegrated ground-state cross section with the (γ, n tot) work of Veyssière et al. indicates that decays to excited states in 18F are much preferred (typically by a factor of 5) over the ground-state channel. The 19F(γ, n 0) cross section shows reasonable agreement in structure and magnitude with the 19F(γ, p 0) cross section of Kerkhove et al. as well as with the 18O(γ, n 0) data of Jury et al. (although some discrepancies are seen at 16 MeV and above 23 MeV).

  18. Study of fusion-fission dynamics in 19F+238U reaction

    NASA Astrophysics Data System (ADS)

    Dubey, R.; Sugathan, P.; Jhingan, A.; Kaur, Gurpreet; Mukul, Ish; Siwal, Davinder; Saneesh, N.; Banerjee, Tathagata; Yadav, Abhishek; Thakur, Meenu; Mahajan, Ruchi; Chaterjee, M. B.

    2016-05-01

    Mass angle distribution measurements for 19F+238U reaction were carried out around the sub barrier energies. Mass angle correlation has not been observed at above and below the fusion barrier in present reaction. This infer the minimal presence of non compound like events at these bombarding energies range.

  19. (1)H and (13)C magic-angle spinning nuclear magnetic resonance studies of the chicken eggshell.

    PubMed

    Pisklak, Dariusz Maciej; Szeleszczuk, Lukasz; Wawer, Iwona

    2012-12-19

    The chicken eggshell, a product of biomineralization, contains inorganic and organic substances whose content changes during the incubation process. Bloch-decay (BD) (1)H, (13)C, and cross-polarization (CP) (13)C nuclear magnetic resonance (NMR) spectra of chicken eggshells were acquired under magic-angle spinning (MAS). Variable contact time (13)C CP MAS NMR experiments revealed the signals of carbonyl groups from organic and inorganic compounds. In the (13)C BD NMR spectra, a single peak at 168.1 ppm was detected, whereas in the (1)H BD spectra, the signals from water and the bicarbonate ion were assigned. A simultaneous decrease of the water signal in the (1)H MAS NMR spectra and an increase of the carbonate ion signal in the (13)C CP MAS NMR spectra of eggshells collected during the incubation period indicate the substitution of calcium ions by hydrogen ions in the calcium carbonate crystalline phase during the incubation of an egg. PMID:23157303

  20. Discrimination of Basal Cell Carcinoma from Normal Skin Tissue Using High-Resolution Magic Angle Spinning 1H NMR Spectroscopy

    PubMed Central

    Mun, Je-Ho; Lee, Heonho; Yoon, Dahye; Kim, Byung-Soo; Kim, Moon-Bum; Kim, Shukmann

    2016-01-01

    High-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy is a useful tool for investigating the metabolism of various cancers. Basal cell carcinoma (BCC) is the most common skin cancer. However, to our knowledge, data on metabolic profiling of BCC have not been reported in the literature. The objective of the present study was to investigate the metabolic profiling of cutaneous BCC using HR-MAS 1H NMR spectroscopy. HR-MAS 1H NMR spectroscopy was used to analyze the metabolite profile and metabolite intensity of histopathologically confirmed BCC tissues and normal skin tissue (NST) samples. The metabolic intensity normalized to the total spectral intensities in BCC and NST was compared, and multivariate analysis was performed with orthogonal partial least-squares discriminant analysis (OPLS-DA). P values < 0.05 were considered statistically significant. Univariate analysis revealed 9 metabolites that showed statistically significant difference between BCC and NST. In multivariate analysis, the OPLS-DA models built with the HR-MAS NMR metabolic profiles revealed a clear separation of BCC from NST. The receiver operating characteristic curve generated from the results revealed an excellent discrimination of BCC from NST with an area under the curve (AUC) value of 0.961. The present study demonstrated that the metabolite profile and metabolite intensity differ between BCC and NST, and that HR-MAS 1H NMR spectroscopy can be a valuable tool in the diagnosis of BCC. PMID:26934749

  1. Evaluation of Cancer Metabolomics Using ex vivo High Resolution Magic Angle Spinning (HRMAS) Magnetic Resonance Spectroscopy (MRS)

    PubMed Central

    Fuss, Taylor L.; Cheng, Leo L.

    2016-01-01

    According to World Health Organization (WHO) estimates, cancer is responsible for more deaths than all coronary heart disease or stroke worldwide, serving as a major public health threat around the world. High resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS) has demonstrated its usefulness in the identification of cancer metabolic markers with the potential to improve diagnosis and prognosis for the oncology clinic, due partially to its ability to preserve tissue architecture for subsequent histological and molecular pathology analysis. Capable of the quantification of individual metabolites, ratios of metabolites, and entire metabolomic profiles, HRMAS MRS is one of the major techniques now used in cancer metabolomic research. This article reviews and discusses literature reports of HRMAS MRS studies of cancer metabolomics published between 2010 and 2015 according to anatomical origins, including brain, breast, prostate, lung, gastrointestinal, and neuroendocrine cancers. These studies focused on improving diagnosis and understanding patient prognostication, monitoring treatment effects, as well as correlating with the use of in vivo MRS in cancer clinics. PMID:27011205

  2. Variable temperature system using vortex tube cooling and fiber optic temperature measurement for low temperature magic angle spinning NMR.

    PubMed

    Martin, Rachel W; Zilm, Kurt W

    2004-06-01

    We describe the construction and operation of a variable temperature (VT) system for a high field fast magic angle spinning (MAS) probe. The probe is used in NMR investigations of biological macromolecules, where stable setting and continuous measurement of the temperature over periods of several days are required in order to prevent sample overheating and degradation. The VT system described is used at and below room temperature. A vortex tube is used to provide cooling in the temperature range of -20 to 20 degrees C, while a liquid nitrogen-cooled heat exchanger is used below -20 degrees C. Using this arrangement, the lowest temperature that is practically achievable is -140 degrees C. Measurement of the air temperature near the spinning rotor is accomplished using a fiber optic thermometer that utilizes the temperature dependence of the absorption edge of GaAs. The absorption edge of GaAs also has a magnetic field dependence that we have measured and corrected for. This dependence was calibrated at several field strengths using the well-known temperature dependence of the (1)H chemical shift difference of the protons in methanol. PMID:15140428

  3. Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Nakamura, Shinji; Fukui, Shigeo; Suematsu, Hiroto; Fujiwara, Toshimichi

    2015-10-01

    Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR = 4-12 kHz) at cryogenic temperatures (T = 35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T = 40 K and B0 = 16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.

  4. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized 13C NMR signals in the 100-200 range are demonstrated with DNP at 25 K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30 K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20-25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids.

  6. Direct determination of phosphate sugars in biological material by (1)H high-resolution magic-angle-spinning NMR spectroscopy.

    PubMed

    Diserens, Gaëlle; Vermathen, Martina; Gjuroski, Ilche; Eggimann, Sandra; Precht, Christina; Boesch, Chris; Vermathen, Peter

    2016-08-01

    The study aim was to unambiguously assign nucleotide sugars, mainly UDP-X that are known to be important in glycosylation processes as sugar donors, and glucose-phosphates that are important intermediate metabolites for storage and transfer of energy directly in spectra of intact cells, as well as in skeletal muscle biopsies by (1)H high-resolution magic-angle-spinning (HR-MAS) NMR. The results demonstrate that sugar phosphates can be determined quickly and non-destructively in cells and biopsies by HR-MAS, which may prove valuable considering the importance of phosphate sugars in cell metabolism for nucleic acid synthesis. As proof of principle, an example of phosphate-sugar reaction and degradation kinetics after unfreezing the sample is shown for a cardiac muscle, suggesting the possibility to follow by HR-MAS NMR some metabolic pathways. Graphical abstract Glucose-phosphate sugars (Glc-1P and Glc-6P) detected in muscle by 1H HR-MAS NMR. PMID:27271261

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

    PubMed Central

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

    2012-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20–25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier (Thurber et al., J. Magn. Reson. 2008) [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids. PMID:23238592

  8. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning.

    PubMed

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states. PMID:26920835

  9. Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR.

    PubMed

    Matsuki, Yoh; Nakamura, Shinji; Fukui, Shigeo; Suematsu, Hiroto; Fujiwara, Toshimichi

    2015-10-01

    Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR=4-12 kHz) at cryogenic temperatures (T=35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T=40 K and B0=16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K. PMID:26302269

  10. Concentration Profiling in Rat Tissue by High-Resolution Magic-Angle Spinning NMR Spectroscopy: Investigation of a Model Drug

    PubMed Central

    Lucas, Laura H.; Wilson, Sarah F.; Lunte, Craig E.; Larive, Cynthia K.

    2008-01-01

    The utility of high-resolution magic-angle spinning (HR-MAS) NMR for studying drug delivery in whole tissues was explored by dosing female Sprague–Dawley rats with topical or injectable benzoic acid (BA). In principle, HR-MAS NMR permits the detection of both intra- and extracellular compounds. This is an advantage over the previous detection of topically applied BA using microdialysis coupled to HPLC/UV as microdialysis samples only the extracellular space. Skin and muscle samples were analyzed by 1H HR-MAS NMR, and BA levels were determined using an external standard solution added to the sample rotor. One to two percent of the BA topical dose was detected in the muscle, showing that BA penetrated through the dermal and subcutaneous layers. Since BA was not detected in the muscle in the microdialysis studies, the NMR spectra revealed the intracellular localization of BA. The amount of BA detected in muscle after subcutaneous injection correlated with the distance from the dosing site. Overall, the results suggest that HR-MAS NMR can distinguish differences in the local concentration of BA varying with tissue type, dosage method, and tissue proximity to the dosing site. The results illustrate the potential of this technique for quantitative analysis of drug delivery and distribution and the challenges to be addressed as the method is refined. PMID:15859619

  11. Satellite transitions acquired in real time by magic angle spinning (STARTMAS): ``Ultrafast'' high-resolution MAS NMR spectroscopy of spin I =3/2 nuclei

    NASA Astrophysics Data System (ADS)

    Thrippleton, Michael J.; Ball, Thomas J.; Wimperis, Stephen

    2008-01-01

    The satellite transitions acquired in real time by magic angle spinning (STARTMAS) NMR experiment combines a train of pulses with sample rotation at the magic angle to refocus the first- and second-order quadrupolar broadening of spin I =3/2 nuclei in a series of echoes, while allowing the isotropic chemical and quadrupolar shifts to evolve. The result is real-time isotropic NMR spectra at high spinning rates using conventional MAS equipment. In this paper we describe in detail how STARTMAS data can be acquired and processed with ease on commercial equipment. We also discuss the advantages and limitations of the approach and illustrate the discussion with numerical simulations and experimental data from four different powdered solids.

  12. Order-selective multiple-quantum excitation in magic-angle spinning NMR: creating triple-quantum coherences with a trilinear Hamiltonian

    NASA Astrophysics Data System (ADS)

    Edén, Mattias

    2002-12-01

    Order-selective multiple-quantum excitation in magic-angle spinning nuclear magnetic resonance is explored using a class of symmetry-based pulse sequences, denoted S Mχ. Simple rules are presented that aid the design of S Mχ schemes with certain desirable effective Hamiltonians. They are applied to construct sequences generating trilinear effective dipolar Hamiltonians, suitable for efficient excitation of triple-quantum coherences in rotating solids. The new sequences are investigated numerically and demonstrated by 1H experiments on adamantane.

  13. Magic-angle-spinning NMR on solid biological systems. Analysis Of the origin of the spectral linewidths

    NASA Astrophysics Data System (ADS)

    Hemminga, M. A.; de Jager, P. A.; Krüse, J.; Lamerichs, R. M. J. N.

    Magic-angle-spinning (MAS) high-power 1H-decoupled 13C and 31P NMR has been applied to solid biological materials to obtain information about the mechanisms that determine the spectral linewidths. The line broadening in MAS 31P NMR spectra of solid tobacco mosaic virus (TMV) has been investigated by selective saturation and T2 measurements. About 90 Hz stems from homogeneous effects, whereas the inhomogeneous contribution is approximately 100 Hz. The inhomogeneous line broadening is assigned to macroscopic inhomogeneities in the sample and not to variations in the nucleotide bases along the RNA strand in TMV. It is concluded that sample preparation is of vital importance for obtaining well-resolved spectra. Under optimal preparation techniques the isotropic values of the chemical shift of the different 31P sites have been determined to obtain information about the secondary structure of the viral RNA. The chemical shift anisotropy has been determined from the relative intensities of the spinning side bands in the spectra. The chemical shift information is used to make a tentative assignment of the resonance in terms of the three structurally distinguishable phosphate groups in TMV. The origin of the linewidths in MAS NMR has been examined further by 13C NMR of approximately 10% 13C-enriched coat protein of cowpea chlorotic mottle virus, using selective excitation and saturation techniques, as well as measurements of the relaxation times T1 γ and T2. The CO resonance in the spectrum is composed of an inhomogeneous and homogeneous part with a total linewidth of 700 Hz. The homogeneous linewidth, contributing with 200 Hz, is found to arise from slow molecular motions in the solid on a millisecond timescale.

  14. Metabolic profiling of a Schistosoma mansoni infection in mouse tissues using magic angle spinning-nuclear magnetic resonance spectroscopy.

    PubMed

    Li, Jia V; Holmes, Elaine; Saric, Jasmina; Keiser, Jennifer; Dirnhofer, Stephan; Utzinger, Jürg; Wang, Yulan

    2009-04-01

    In order to enhance our understanding of physiological and pathological consequences of a patent Schistosoma mansoni infection in the mouse, we examined the metabolic responses of different tissue samples recovered from the host animal using a metabolic profiling strategy. Ten female NMRI mice were infected with approximately 80 S. mansoni cercariae each, and 10 uninfected age- and sex-matched animals served as controls. At day 74 post infection (p.i.), mice were killed and jejunum, ileum, colon, liver, spleen and kidney samples were removed. We employed (1)H magic angle spinning-nuclear magnetic resonance spectroscopy to generate tissue-specific metabolic profiles. The spectral data were analyzed using multivariate modelling methods including an orthogonal signal corrected-projection to latent structure analysis and hierarchical principal component analysis to assess the differences and/or similarities in metabolic responses between infected and non-infected control mice. Most tissues obtained from S. mansoni-infected mice were characterized by high levels of amino acids, such as leucine, isoleucine, lysine, glutamine and asparagine. High levels of membrane phospholipid metabolites, including glycerophosphoryl choline and phosphoryl choline were found in the ileum, colon, liver and spleen of infected mice. Additionally, low levels of energy-related metabolites, including lipids, glucose and glycogen were observed in ileum, spleen and liver samples of infected mice. Energy-related metabolites in the jejunum, liver and renal medulla were found to be positively correlated with S. mansoni worm burden upon dissection. These findings show that a patent S. mansoni infection causes clear disruption of metabolism in a range of tissues at a molecular level, which can be interpreted in relation to the previously reported signature in a biofluid (i.e. urine), giving further evidence of the global effect of the infection. PMID:19068218

  15. Distortional binding of transition state analogs to human purine nucleoside phosphorylase probed by magic angle spinning solid-state NMR.

    PubMed

    Vetticatt, Mathew J; Itin, Boris; Evans, Gary B; Schramm, Vern L

    2013-10-01

    Transition state analogs mimic the geometry and electronics of the transition state of enzymatic reactions. These molecules bind to the active site of the enzyme much tighter than substrate and are powerful noncovalent inhibitors. Immucillin-H (ImmH) and 4'-deaza-1'-aza-2'-deoxy-9-methylene Immucillin-H (DADMe-ImmH) are picomolar inhibitors of human purine nucleoside phosphorylase (hPNP). Although both molecules are electronically similar to the oxocarbenium-like dissociative hPNP transition state, DADMe-ImmH is more potent than ImmH. DADMe-ImmH captures more of the transition state binding energy by virtue of being a closer geometric match to the hPNP transition state than ImmH. A consequence of these similarities is that the active site of hPNP exerts greater distortional forces on ImmH than on DADMe-ImmH to "achieve" the hPNP transition state geometry. By using magic angle spinning solid-state NMR to investigate stable isotope-labeled ImmH and DADMe-ImmH, we have explored the difference in distortional binding of these two inhibitors to hPNP. High-precision determinations of internuclear distances from NMR recoupling techniques, rotational echo double resonance, and rotational resonance, have provided unprecedented atomistic insight into the geometric changes that occur upon binding of transition state analogs. We conclude that hPNP stabilizes conformations of these chemically distinct analogs having distances between the cation and leaving groups resembling those of the known transition state. PMID:24043827

  16. Live-cell high resolution magic angle spinning magnetic resonance spectroscopy for in vivo analysis of Pseudomonas aeruginosa metabolomics.

    PubMed

    Righi, Valeria; Constantinou, Caterina; Kesarwani, Meenu; Rahme, Laurence G; Tzika, Aria A

    2013-09-01

    Pseudomonas aeruginosa (PA) is a pathogenic gram-negative bacterium that is widespread in nature, inhabiting soil, water, plants and animals. PA is a prevalent cause of deleterious human infections, particularly in patients whose host defense mechanisms have been compromised. Metabolomics is an important tool used to study host-pathogen interactions and to identify novel therapeutic targets and corresponding compounds. The aim of the present study was to report the metabolic profile of live PA bacteria using in vivo high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance spectroscopy (NMR), in combination with 1- and 2-dimensional HRMAS NMR. This methodology provides a new and powerful technique to rapidly interrogate the metabolome of intact bacterial cells and has several advantages over traditional techniques that identify metabolome components from disrupted cells. Furthermore, application of multidimensional HRMAS NMR, in combination with the novel technique total through-Bond correlation Spectroscopy (TOBSY), is a promising approach that may be used to obtain in vivo metabolomics information from intact live bacterial cells and can mediate such analyses in a short period of time. Moreover, HRMAS (1)H NMR enables the investigation of the associations between metabolites and cell processes. In the present study, we detected and quantified several informative metabolic molecules in live PA cells, including N-acetyl, betaine, citrulline, alanine and glycine, which are important in peptidoglycan synthesis. The results provided a complete metabolic profile of PA for future studies of PA clinical isolates and mutants. In addition, this in vivo NMR biomedical approach might have clinical utility and should prove useful in gene function validation, the study of pathogenetic mechanisms, the classification of microbial strains into functional/clinical groups, the testing of anti-bacterial agents and the determination of metabolic profiles of bacterial

  17. Characterization of metabolites in infiltrating gliomas using ex vivo ¹H high-resolution magic angle spinning spectroscopy.

    PubMed

    Elkhaled, Adam; Jalbert, Llewellyn; Constantin, Alexandra; Yoshihara, Hikari A I; Phillips, Joanna J; Molinaro, Annette M; Chang, Susan M; Nelson, Sarah J

    2014-05-01

    Gliomas are routinely graded according to histopathological criteria established by the World Health Organization. Although this classification can be used to understand some of the variance in the clinical outcome of patients, there is still substantial heterogeneity within and between lesions of the same grade. This study evaluated image-guided tissue samples acquired from a large cohort of patients presenting with either new or recurrent gliomas of grades II-IV using ex vivo proton high-resolution magic angle spinning spectroscopy. The quantification of metabolite levels revealed several discrete profiles associated with primary glioma subtypes, as well as secondary subtypes that had undergone transformation to a higher grade at the time of recurrence. Statistical modeling further demonstrated that these metabolomic profiles could be differentially classified with respect to pathological grading and inter-grade conversions. Importantly, the myo-inositol to total choline index allowed for a separation of recurrent low-grade gliomas on different pathological trajectories, the heightened ratio of phosphocholine to glycerophosphocholine uniformly characterized several forms of glioblastoma multiforme, and the onco-metabolite D-2-hydroxyglutarate was shown to help distinguish secondary from primary grade IV glioma, as well as grade II and III from grade IV glioma. These data provide evidence that metabolite levels are of interest in the assessment of both intra-grade and intra-lesional malignancy. Such information could be used to enhance the diagnostic specificity of in vivo spectroscopy and to aid in the selection of the most appropriate therapy for individual patients. PMID:24596146

  18. Application of High-Resolution Magic-Angle Spinning NMR Spectroscopy to Define the Cell Uptake of MRI Contrast Agents

    NASA Astrophysics Data System (ADS)

    Calabi, Luisella; Alfieri, Goffredo; Biondi, Luca; De Miranda, Mario; Paleari, Lino; Ghelli, Stefano

    2002-06-01

    A new method, based on proton high-resolution magic-angle spinning ( 1H HR-MAS) NMR spectroscopy, has been employed to study the cell uptake of magnetic resonance imaging contrast agents (MRI-CAs). The method was tested on human red blood cells (HRBC) and white blood cells (HWBC) by using three gadolinium complexes, widely used in diagnostics, Gd-BOPTA, Gd-DTPA, and Gd-DOTA, and the analogous complexes obtained by replacing Gd(III) with Dy(III), Nd(III), and Tb(III) (i.e., complexes isostructural to the ones of gadolinium but acting as shift agents). The method is based on the evaluation of the magnetic effects, line broadening, or induced lanthanide shift (LIS) caused by these complexes on NMR signals of intra- and extracellular water. Since magnetic effects are directly linked to permeability, this method is direct. In all the tests, these magnetic effects were detected for the extracellular water signal only, providing a direct proof that these complexes are not able to cross the cell membrane. Line broadening effects (i.e., the use of gadolinium complexes) only allow qualitative evaluations. On the contrary, LIS effects can be measured with high precision and they can be related to the concentration of the paramagnetic species in the cellular compartments. This is possible because the HR-MAS technique provides the complete elimination of bulk magnetic susceptibility (BMS) shift and the differentiation of extra- and intracellular water signals. Thus with this method, the rapid quantification of the MRI-CA amount inside and outside the cells is actually feasible.

  19. Magic-Angle Spinning Solid-State NMR Spectroscopy of Nanodisc– Embedded Human CYP3A4†

    PubMed Central

    Kijac, Aleksandra; Li, Ying; Sligar, Stephen G.; Rienstra, Chad M.

    2008-01-01

    Cytochrome P450 (CYP) 3A4 contributes to the metabolism of approximately 50% of commercial drugs by oxidizing a large number of structurally diverse substrates. Like other endoplasmic reticulum-localized P450s, CYP3A4 contains a membrane-anchoring N-terminal helix and a significant number of hydrophobic domains, important for the interaction between CYP3A4 and the membrane. Although the membrane affects specificity of CYP3A4 ligand binding, the structural details of the interaction have not been revealed so far because x-ray crystallography studies are available only for the soluble domain of CYP3A4. Here we report sample preparation and initial magic-angle spinning (MAS) solid-state NMR (SSNMR) of CYP3A4 (Δ3−12) embedded in a nanoscale membrane bilayer, or Nanodisc. The growth protocol yields ∼2.5 mg of the enzymatically active, uniformly 13C, 15N-enriched CYP3A4 from a liter of growth medium. Polyethylene glycol 3350-precipitated CYP3A4 in Nanodiscs yields spectra of high resolution and sensitivity, consistent with a folded, homogeneous protein. CYP3A4 in Nanodiscs remains enzymatically active throughout the precipitation protocol as monitored by bromocriptine binding. The 13C line widths measured from 13C-13C 2D chemical shift correlation spectra are ∼0.5 ppm. The secondary structure distribution within several amino acid types determined from 13C chemical shifts is consistent with the ligand-free x-ray structures. These results demonstrate that MAS SSNMR can be performed on Nanodisc-embedded membrane proteins in a folded, active state. The combination of SSNMR and Nanodisc methodologies opens up new possibilities for obtaining structural information on CYP3A4 and other integral membrane proteins with full retention of functionality. PMID:17985934

  20. High-resolution paramagnetically enhanced solid-state NMR spectroscopy of membrane proteins at fast magic angle spinning.

    PubMed

    Ward, Meaghan E; Wang, Shenlin; Krishnamurthy, Sridevi; Hutchins, Howard; Fey, Michael; Brown, Leonid S; Ladizhansky, Vladimir

    2014-01-01

    Magic angle spinning nuclear magnetic resonance (MAS NMR) is well suited for the study of membrane proteins in membrane mimetic and native membrane environments. These experiments often suffer from low sensitivity, due in part to the long recycle delays required for magnetization and probe recovery, as well as detection of low gamma nuclei. In ultrafast MAS experiments sensitivity can be enhanced through the use of low power sequences combined with paramagnetically enhanced relaxation times to reduce recycle delays, as well as proton detected experiments. In this work we investigate the sensitivity of (13)C and (1)H detected experiments applied to 27 kDa membrane proteins reconstituted in lipids and packed in small 1.3 mm MAS NMR rotors. We demonstrate that spin diffusion is sufficient to uniformly distribute paramagnetic relaxation enhancement provided by either covalently bound or dissolved CuEDTA over 7TM alpha helical membrane proteins. Using paramagnetic enhancement and low power decoupling in carbon detected experiments we can recycle experiments ~13 times faster than under traditional conditions. However, due to the small sample volume the overall sensitivity per unit time is still lower than that seen in the 3.2 mm probe. Proton detected experiments, however, showed increased efficiency and it was found that the 1.3 mm probe could achieve sensitivity comparable to that of the 3.2 mm in a given amount of time. This is an attractive prospect for samples of limited quantity, as this allows for a reduction in the amount of protein that needs to be produced without the necessity for increased experimental time. PMID:24338448

  1. Intratumoral Agreement of High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopic Profiles in the Metabolic Characterization of Breast Cancer

    PubMed Central

    Park, Vivian Youngjean; Yoon, Dahye; Koo, Ja Seung; Kim, Eun-Kyung; Kim, Seung Il; Choi, Ji Soo; Park, Seho; Park, Hyung Seok; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Abstract High-resolution magic angle spinning (HR-MAS) magnetic resonance (MR) spectroscopy data may serve as a biomarker for breast cancer, with only a small volume of tissue sample required for assessment. However, previous studies utilized only a single tissue sample from each patient. The aim of this study was to investigate whether intratumoral location and biospecimen type affected the metabolic characterization of breast cancer assessed by HR-MAS MR spectroscopy This prospective study was approved by the institutional review board and informed consent was obtained. Preoperative core-needle biopsies (CNBs), central, and peripheral surgical tumor specimens were prospectively collected under ultrasound (US) guidance in 31 patients with invasive breast cancer. Specimens were assessed with HR-MAS MR spectroscopy. The reliability of metabolite concentrations was evaluated and multivariate analysis was performed according to intratumoral location and biospecimen type. There was a moderate or higher agreement between the relative concentrations of 94.3% (33 of 35) of metabolites in the center and periphery, 80.0% (28 of 35) of metabolites in the CNB and central surgical specimens, and 82.9% (29 of 35) of metabolites between all 3 specimen types. However, there was no significant agreement between the concentrations of phosphocholine (PC) and phosphoethanolamine (PE) in the center and periphery. The concentrations of several metabolites (adipate, arginine, fumarate, glutamate, PC, and PE) had no significant agreement between the CNB and central surgical specimens. In conclusion, most HR-MAS MR spectroscopic data do not differ based on intratumoral location or biospecimen type. However, some metabolites may be affected by specimen-related variables, and caution is recommended in decision-making based solely on metabolite concentrations, particularly PC and PE. Further validation through future studies is needed for the clinical implementation of these biomarkers based

  2. The mobility of chondroitin sulfate in articular and artificial cartilage characterized by 13C magic-angle spinning NMR spectroscopy.

    PubMed

    Scheidt, Holger A; Schibur, Stephanie; Magalhães, Alvicler; de Azevedo, Eduardo R; Bonagamba, Tito J; Pascui, Ovidiu; Schulz, Ronny; Reichert, Detlef; Huster, Daniel

    2010-06-01

    We have studied the molecular dynamics of one of the major macromolecules in articular cartilage, chondroitin sulfate. Applying (13)C high-resolution magic-angle spinning NMR techniques, the NMR signals of all rigid macromolecules in cartilage can be suppressed, allowing the exclusive detection of the highly mobile chondroitin sulfate. The technique is also used to detect the chondroitin sulfate in artificial tissue-engineered cartilage. The tissue-engineered material that is based on matrix producing chondrocytes cultured in a collagen gel should provide properties as close as possible to those of the natural cartilage. Nuclear relaxation times of the chondroitin sulfate were determined for both tissues. Although T(1) relaxation times are rather similar, the T(2) relaxation in tissue-engineered cartilage is significantly shorter. This suggests that the motions of chondroitin sulfate in natural and artificial cartilage are different. The nuclear relaxation times of chondroitin sulfate in natural and tissue-engineered cartilage were modeled using a broad distribution function for the motional correlation times. Although the description of the microscopic molecular dynamics of the chondroitin sulfate in natural and artificial cartilage required the identical broad distribution functions for the correlation times of motion, significant differences in the correlation times of motion that are extracted from the model indicate that the artificial tissue does not fully meet the standards of the natural ideal. This could also be confirmed by macroscopic biomechanical elasticity measurements. Nevertheless, these results suggest that NMR is a useful tool for the investigation of the quality of artificially engineered tissue. PMID:20091673

  3. Mineral Carbonation in Wet Supercritical CO2: An in situ High-Pressure Magic Angle Spinning Nuclear Magnetic Resonance Study

    NASA Astrophysics Data System (ADS)

    Turcu, R. V.; Hoyt, D. H.; Sears, J. A.; Rosso, K. M.; Felmy, A. R.; Hu, J. Z.

    2011-12-01

    Understanding the mechanisms and kinetics of mineral carbonation reactions relevant to sequestering carbon dioxide as a supercritical fluid (scCO2) in geologic formations is crucial for accurately predicting long-term storage risks. In situ probes that provide molecular-level information at geologically relevant temperatures and pressures are highly desirable and challenging to develop. Magic angle spinning nuclear magnetic resonance (MAS NMR) is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, a supercritical state, or a mixture thereof. However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS sample rotor. In this work, we report development of a unique high pressure MAS NMR capability capable of handling fluid pressure exceeding 170 bars and temperatures up to 80°C, and its application to mineral carbonation in scCO2 under geologically relevant temperatures and pressures. Mineral carbonation reactions of the magnesium silicate mineral forsterite and the magnesium hydroxide brucite reacted with scCO2 (up to 170 bar) and containing variable content of H2O (at, below, and above saturation in scCO2) were investigated at 50 to 70°C. In situ 13C MAS NMR spectra show peaks corresponding to the reactants, intermediates, and the magnesium carbonation products in a single spectrum. For example, Figure 1 shows the reaction dynamics, i.e., the formation and conversion of reaction intermediates, i.e., HCO3- and nesquehonite, to magnesite as a function of time at 70°C. This capability offers a significant advantage over traditional ex situ 13C MAS experiments on similar systems, where, for example, CO2 and HCO3- are not directly observable.

  4. Complete protocol for slow-spinning high-resolution magic-angle spinning NMR analysis of fragile tissues.

    PubMed

    André, Marion; Dumez, Jean-Nicolas; Rezig, Lamya; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano

    2014-11-01

    High-resolution magic-angle spinning (HR-MAS) nuclear magnetic resonance (NMR) is an essential tool to characterize a variety of semisolid systems, including biological tissues, with virtually no sample preparation. The "non-destructive" nature of NMR is typically compromised, however, by the extreme centrifugal forces experienced under conventional HR-MAS frequencies of several kilohertz. These features limit the usefulness of current HR-MAS approaches for fragile samples. Here, we introduce a full protocol for acquiring high-quality HR-MAS NMR spectra of biological tissues at low spinning rates (down to a few hundred hertz). The protocol first consists of a carefully designed sample preparation, which yields spectra without significant spinning sidebands at low spinning frequency for several types of sample holders, including the standard disposable inserts classically used in HR-MAS NMR-based metabolomics. Suppression of broad spectral features is then achieved using a modified version of the recently introduced PROJECT experiment with added water suppression and rotor synchronization, which deposits limited power in the sample and which can be suitably rotor-synchronized at low spinning rates. The performance of the slow HR-MAS NMR procedure is demonstrated on conventional (liver tissue) and very delicate (fish eggs) samples, for which the slow-spinning conditions are shown to preserve the structural integrity and to minimize intercompartmental leaks of metabolites. Taken together, these results expand the applicability and reliability of HR-MAS NMR spectroscopy. These results have been obtained at 400 and 600 MHz and suggest that high-quality slow HR-MAS spectra can be expected at higher magnetic fields using the described protocol. PMID:25286333

  5. Powder-XRD and (14) N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides.

    PubMed

    Kempgens, Pierre; Britton, Jonathan

    2016-05-01

    Some metal nitrides (TiN, ZrN, InN, GaN, Ca3 N2 , Mg3 N2 , and Ge3 N4 ) have been studied by powder X-ray diffraction (XRD) and (14) N magic angle-spinning (MAS) solid-state NMR spectroscopy. For Ca3 N2 , Mg3 N2 , and Ge3 N4 , no (14) N NMR signal was observed. Low speed (νr  = 2 kHz for TiN, ZrN, and GaN; νr  = 1 kHz for InN) and 'high speed' (νr  = 15 kHz for TiN; νr  = 5 kHz for ZrN; νr  = 10 kHz for InN and GaN) MAS NMR experiments were performed. For TiN, ZrN, InN, and GaN, powder-XRD was used to identify the phases present in each sample. The number of peaks observed for each sample in their (14) N MAS solid-state NMR spectrum matches perfectly well with the number of nitrogen-containing phases identified by powder-XRD. The (14) N MAS solid-state NMR spectra are symmetric and dominated by the quadrupolar interaction. The envelopes of the spinning sidebands manifold are Lorentzian, and it is concluded that there is a distribution of the quadrupolar coupling constants Qcc 's arising from structural defects in the compounds studied. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26687421

  6. 19F MRI for quantitative in vivo cell tracking

    PubMed Central

    Srinivas, Mangala; Heerschap, Arend; Ahrens, Eric T.; Figdor, Carl G.; de Vries, I. Jolanda M.

    2010-01-01

    Cellular therapy, including stem cell transplants and dendritic cell vaccines, is typically monitored for dosage optimization, accurate delivery and localization using non-invasive imaging, of which magnetic resonance imaging (MRI) is a key modality. 19F MRI retains the advantages of MRI as an imaging modality, while allowing direct detection of labelled cells for unambiguous identification and quantification, unlike typical metal-based contrast agents. Recent developments in 19F MRI-based in vivo cell quantification, the existing clinical use of 19F compounds and current explosive interest in cellular therapeutics have brought 19F imaging technology closer to clinical application. We review the application of 19F MRI to cell tracking, discussing intracellular 19F labels, cell labelling and in vivo quantification, as well as the potential clinical use of 19F MRI. PMID:20427096

  7. CP-MAS 207Pb with 19F decoupling NMR spectroscopy: medium range investigation in fluoride materials.

    PubMed

    Bureau, B; Silly, G; Buzaré, J Y

    1999-11-01

    The isotropic chemical shift of 207Pb is used to perform structural investigations of crystalline fluoride compounds (PbF2, Pb2ZnF6, PbGaF5, Pb3Ga2F12 and Pb9Ga2F24) and transition metal fluoride glasses (TMFG) of the PZG family (PbF2-ZnF2-GaF3). Using 207Pb Cross Polarisation Magic Angle Spinning (CP-MAS) NMR with 19F decoupling, it is shown that the isotropic chemical shift of 207Pb varies on a large scale (1000 ppm) and that the main changes of its value are not due to the nearest neighbour fluorines but may be related to the number of next nearest neighbour (nnn) Pb2+ ions. In this way, it is demonstrated that 207Pb chemical shift is an interesting probe to investigate medium range order in either crystalline or glassy fluoride systems. The 207Pb delta(iso) parameter has been linearly correlated to the number of nnn Pb2+ ions. PMID:10670899

  8. Sensitivity and resolution enhanced solid-state NMR for paramagnetic systems and biomolecules under very fast magic angle spinning.

    PubMed

    Parthasarathy, Sudhakar; Nishiyama, Yusuke; Ishii, Yoshitaka

    2013-09-17

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

  9. Spin dynamics in the modulation frame: application to homonuclear recoupling in magic angle spinning solid-state NMR.

    PubMed

    De Paëpe, Gaël; Lewandowski, Józef R; Griffin, Robert G

    2008-03-28

    We introduce a family of solid-state NMR pulse sequences that generalizes the concept of second averaging in the modulation frame and therefore provides a new approach to perform magic angle spinning dipolar recoupling experiments. Here, we focus on two particular recoupling mechanisms-cosine modulated rotary resonance (CMpRR) and cosine modulated recoupling with isotropic chemical shift reintroduction (COMICS). The first technique, CMpRR, is based on a cosine modulation of the rf phase and yields broadband double-quantum (DQ) (13)C recoupling using >70 kHz omega(1,C)/2pi rf field for the spinning frequency omega(r)/2=10-30 kHz and (1)H Larmor frequency omega(0,H)/2pi up to 900 MHz. Importantly, for p>or=5, CMpRR recouples efficiently in the absence of (1)H decoupling. Extension to lower p values (3.5

  10. A bisphosphonate for 19F-magnetic resonance imaging

    PubMed Central

    Kenny, Gavin D.; Shaw, Karen P.; Sivachelvam, Saranja; White, Andrew J.P.; Botnar, Rene M.; T.M. de Rosales, Rafael

    2016-01-01

    19F-magnetic resonance imaging (MRI) is a promising technique that may allow us to measure the concentration of exogenous fluorinated imaging probes quantitatively in vivo. Here, we describe the synthesis and characterisation of a novel geminal bisphosphonate (19F-BP) that contains chemically-equivalent fluorine atoms that show a single and narrow 19F resonance and a bisphosphonate group that may be used for labelling inorganic materials based in calcium phosphates and metal oxides. The potential of 19F-BP to provide contrast was analysed in vitro and in vivo using 19F-MRI. In vitro studies demonstrated the potential of 19F-BP as an MRI contrast agent in the millimolar concentration range with signal-to-noise ratios (SNR) comparable to previously reported fluorinated probes. The preliminary in vivo MRI study reported here allowed us to visualise the biodistribution of 19F-BP, showing uptake in the liver and in the bladder/urinary system areas. However, bone uptake was not observed. In addition, 19F-BP showed undesirable toxicity effects in mice that prevent further studies with this compound at the required concentrations for MRI contrast. This study highlights the importance of developing 19F MRI probes with the highest signal intensity achievable. PMID:27110036

  11. Complete fusion of 19F with Al and Si isotopes

    NASA Astrophysics Data System (ADS)

    Chiou, M. S.; Wu, M. W.; Easwar, N.; Maher, J. V.

    1981-12-01

    Complete fusion cross sections have been determined by directly detecting evaporation residuals for the systems 19F + 27Al and 19F + 28,30Si over a 19F laboratory energy range 34-75 MeV. In all cases σfus increases smoothly with energy and eventually saturates at 1200-1250 mb. In the barrier penetration region the cross section for 19F + 28Si is always sufficiently smaller than that for 19F + 30Si to make the reduced barrier radius in a Glas-Mosel parametrization significantly smaller for the former system than for the latter. Three entrance channels are now available for the fused-system 46Ti: Critical angular momentum data from the 16O + 30Si entrance channel approach the statistical yrast line at much lower fused-system excitation energy than do the data from the entrance channels 18O + 28Si and 19F + 27Al. NUCLEAR REACTIONS Measured complete fusion cross sections for the systems 19F + 27Al, 19F + 28Si, 19F + 30Si; E=34-75 MeV. Deduced Glas-Mosel model and statistical yrast model parameters.

  12. A suite of pulse sequences based on multiple sequential acquisitions at one and two radiofrequency channels for solid-state magic-angle spinning NMR studies of proteins.

    PubMed

    Sharma, Kshama; Madhu, Perunthiruthy K; Mote, Kaustubh R

    2016-08-01

    One of the fundamental challenges in the application of solid-state NMR is its limited sensitivity, yet a majority of experiments do not make efficient use of the limited polarization available. The loss in polarization in a single acquisition experiment is mandated by the need to select out a single coherence pathway. In contrast, sequential acquisition strategies can encode more than one pathway in the same experiment or recover unused polarization to supplement a standard experiment. In this article, we present pulse sequences that implement sequential acquisition strategies on one and two radiofrequency channels with a combination of proton and carbon detection to record multiple experiments under magic-angle spinning. We show that complementary 2D experiments such as [Formula: see text] and [Formula: see text] or DARR and [Formula: see text], and 3D experiments such as [Formula: see text] and [Formula: see text], or [Formula: see text] and [Formula: see text]  can be combined in a single experiment to ensure time savings of at least 40 %. These experiments can be done under fast or slow-moderate magic-angle spinning frequencies aided by windowed [Formula: see text] acquisition and homonulcear decoupling. The pulse sequence suite is further expanded by including pathways that allow the recovery of residual polarization, the so-called 'afterglow' pathways, to encode a number of pulse sequences to aid in assignments and chemical-shift mapping. PMID:27364976

  13. Slow Magic Angle Sample Spinning: A Non- or Minimally Invasive Method for High- Resolution 1H Nuclear Magnetic Resonance (NMR) Metabolic Profiling

    SciTech Connect

    Hu, Jian Z.

    2011-05-01

    High resolution 1H magic angle spinning nuclear magnetic resonance (NMR), using a sample spinning rate of several kHz or more (i.e., high resolution-magic angle spinning (hr-MAS)), is a well established method for metabolic profiling in intact tissues without the need for sample extraction. The only shortcoming with hr-MAS is that it is invasive and is thus unusable for non-destructive detections. Recently, a method called slow-MAS, using the concept of two dimensional NMR spectroscopy, has emerged as an alternative method for non- or minimal invasive metabolomics in intact tissues, including live animals, due to the slow or ultra-slow-sample spinning used. Although slow-MAS is a powerful method, its applications are hindered by experimental challenges. Correctly designing the experiment and choosing the appropriate slow-MAS method both require a fundamental understanding of the operation principles, in particular the details of line narrowing due to the presence of molecular diffusion. However, these fundamental principles have not yet been fully disclosed in previous publications. The goal of this chapter is to provide an in depth evaluation of the principles associated with slow-MAS techniques by emphasizing the challenges associated with a phantom sample consisting of glass beads and H2O, where an unusually large magnetic susceptibility field gradient is obtained.

  14. Unexpected effects of third-order cross-terms in heteronuclear spin systems under simultaneous radio-frequency irradiation and magic-angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Tatton, Andrew S.; Frantsuzov, Ilya; Brown, Steven P.; Hodgkinson, Paul

    2012-02-01

    We recently noted [R. K. Harris, P. Hodgkinson, V. Zorin, J.-N. Dumez, B. Elena, L. Emsley, E. Salager, and R. Stein, Magn. Reson. Chem. 48, S103 (2010), 10.1002/mrc.2636] anomalous shifts in apparent 1H chemical shifts in experiments using 1H homonuclear decoupling sequences to acquire high-resolution 1H NMR spectra for organic solids under magic-angle spinning (MAS). Analogous effects were also observed in numerical simulations of model 13C,1H spin systems under homonuclear decoupling and involving large 13C,1H dipolar couplings. While the heteronuclear coupling is generally assumed to be efficiently suppressed by sample spinning at the magic angle, we show that under conditions typically used in solid-state NMR, there is a significant third-order cross-term from this coupling under the conditions of simultaneous MAS and homonuclear decoupling for spins directly bonded to 1H. This term, which is of the order of 100 Hz under typical conditions, explains the anomalous behaviour observed on both 1H and 13C spins, including the fast dephasing observed in 13C{1H} heteronuclear spin-echo experiments under 1H homonuclear decoupling. Strategies for minimising the impact of this effect are also discussed.

  15. Slow magic-angle rotation 13C NMR studies of solid phosphonium iodides. The interplay of dipolar, shielding, and indirect coupling tensors

    NASA Astrophysics Data System (ADS)

    Harris, Robin K.; Packer, Kenneth J.; Thayer, Ann M.

    High-resolution 13C NMR spectra were recorded for solid [Me 2Ph 2P] +I - and [Me 3PhP] +I - using high-power decoupling, cross-polarization, and magic-angle rotation. Spectra of the ipso carbon, obtained with the nonquaternary suppression (dipolar dephasing) pulse sequence, show an unequal distribution intensity of spinning sidebands for the two peaks split by the isotropic coupling constant 1JPC. This effect is traced to the joint influence of (P, C) dipolar coupling and 13C shielding anisotropy. The existence of scalar coupling enables magic-angle rotation to distinguish the two subspectra which are present. Analysis of the sideband patterns yields values of the NMR parameters. Under certain assumptions, including that the axis of greatest shielding is perpendicular to the PC bond, it is shown that 1JPC is positive. In contrast to traditional methods of determining signs, this conclusion does not rely on knowledge of signs of other coupling constants.

  16. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI

    NASA Astrophysics Data System (ADS)

    Yesinowski, James P.; Ladouceur, Harold D.; Purdy, Andrew P.; Miller, Joel B.

    2010-12-01

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the 207Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu+ vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the 63Cu and 127I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for 63Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by rotating a

  17. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI.

    PubMed

    Yesinowski, James P; Ladouceur, Harold D; Purdy, Andrew P; Miller, Joel B

    2010-12-21

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves (63)Cu, (65)Cu, and (127)I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu(+)-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the (207)Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu(+) vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the (63)Cu and (127)I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for (63)Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by

  18. 19F magnetic resonance imaging of endogenous macrophages in inflammation.

    PubMed

    Temme, Sebastian; Bönner, Florian; Schrader, Jürgen; Flögel, Ulrich

    2012-01-01

    In this article, we review the use of (19) F MRI (magnetic resonance imaging) for in vivo tracking of monocytes and macrophages in the course of tissue inflammation. Emulsified perfluorocarbons (PFCs) are preferentially phagocytized by monocytes/macrophages and are readily detected by (19) F MRI. Because of the lack of any (19) F background in the body, observed signals are robust and exhibit an excellent degree of specificity. As a consequence of progressive infiltration of the labeled immunocompetent cells into inflamed areas, foci of inflammation can be localized as hot spots by simultaneous acquisition of morphologically matched proton ((1) H) and fluorine ((19) F) MRI. The identification of inflammation by (19) F MRI--at a time when the inflammatory cascade is initiated--opens the possibility for an early detection and more timely therapeutic intervention. Since signal intensity in the (19) F images reflects the severity of inflammation, this approach is also suitable to monitor the efficacy of pharmaceutical treatment. Because PFCs are biochemically inert and the fluorine nucleus exhibits high magnetic resonance (MR) sensitivity, (19) F MRI may be applicable for clinical inflammation imaging. PMID:22354793

  19. Recent developments in solid-state magic-angle spinning, nuclear magnetic resonance of fully and significantly isotopically labelled peptides and proteins.

    PubMed Central

    Straus, Suzana K

    2004-01-01

    In recent years, a large number of solid-state nuclear magnetic resonance (NMR) techniques have been developed and applied to the study of fully or significantly isotopically labelled ((13)C, (15)N or (13)C/(15)N) biomolecules. In the past few years, the first structures of (13)C/(15)N-labelled peptides, Gly-Ile and Met-Leu-Phe, and a protein, Src-homology 3 domain, were solved using magic-angle spinning NMR, without recourse to any structural information obtained from other methods. This progress has been made possible by the development of NMR experiments to assign solid-state spectra and experiments to extract distance and orientational information. Another key aspect to the success of solid-state NMR is the advances made in sample preparation. These improvements will be reviewed in this contribution. Future prospects for the application of solid-state NMR to interesting biological questions will also briefly be discussed. PMID:15306412

  20. {sup 129}Xe magic-angle spinning spectra of xenon in zeolite NaA direct observation of mixed clusters of co-adsorbed species.

    SciTech Connect

    Jameson, A. K.; Jameson, C. J.; de Dios, A. C.; Oldfield, E.; Gerald, R. E., II; Turner, G. L.; Chemical Engineering; Loyola Univ.; Univ. of Illinois at Chicago; Univ. of Illinois; Spectral Data Services, Inc.

    1995-01-01

    We present the first demonstration that the individual {sup 129}Xe resonances corresponding to Xe{sub n} (n = 1-8) clusters inside the {alpha}-cages of zeolite NaA can be narrowed under magic-angle spinning (MAS). Under these high-resolution conditions we also observe upon addition of Kr the individual peaks corresponding to mixed clusters, Xe{sub n}Kr{sub m}, inside the a-cages, which will allow the first direct determination of the distribution of co-adsorbates in a microporous solid. Under MAS the chemical shifts of the Xe{sub n} clusters are shown to be highly sensitive to 'disorder' in the zeolite and provides new, quantitative information about the presence of {alpha}-cages of several types.

  1. Two-Dimensional NMR Study of a Liquid-Crystal Solution under Magic-Angle Spinning. Conformation of Carboxylic Ionophore Lasalocid A Dissolved in a Lyotropic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Kimura, Atsuomi; Kano, Tetsushi; Fujiwara, Hideaki

    1996-07-01

    The conformation of a carboxylic ionophore, lasalocid A, has been determined in a lyotropic liquid crystal by means of magic-angle spinning (MAS) and two-dimensional NMR experiments. The information extracted from ROESY spectra measured under MAS was analyzed according to the distance-geometry algorithm. The liquid crystal used for the solvent is cesium perfluorooctanoate dissolved in D2O, and the resulting structure of lasalocid A is a cyclic one, indicating cation complexation within a hydrophobic region of the liquid crystal. In this way, the two-dimensional MAS NMR experiment is proved to be a useful technique in conformational studies of complex molecules dissolved in lyotropic liquid crystal which may be regarded as offering a membrane-like environment.

  2. Crocus sativus Petals: Waste or Valuable Resource? The Answer of High-Resolution and High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance.

    PubMed

    Righi, Valeria; Parenti, Francesca; Tugnoli, Vitaliano; Schenetti, Luisa; Mucci, Adele

    2015-09-30

    Intact Crocus sativus petals were studied for the first time by high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy, revealing the presence of kinsenoside (2) and goodyeroside A (3), together with 3-hydroxy-γ-butyrolactone (4). These findings were confirmed by HR-NMR analysis of the ethanol extract of fresh petals and showed that, even though carried out rapidly, partial hydrolysis of glucopyranosyloxybutanolides occurs during extraction. On the other hand, kaempferol 3-O-sophoroside (1), which is "NMR-silent" in intact petals, is present in extracts. These results suggest to evaluate the utilization of saffron petals for phytopharmaceutical and nutraceutical purposes to exploit a waste product of massive production of commercial saffron and point to the application of HR-MAS NMR for monitoring bioactive compounds directly on intact petals, avoiding the extraction procedure and the consequent hydrolysis reaction. PMID:26367873

  3. Caught in the act: ATP hydrolysis of an ABC-multidrug transporter followed by real-time magic angle spinning NMR.

    PubMed

    Hellmich, Ute A; Haase, Winfried; Velamakanni, Saroj; van Veen, Hendrik W; Glaubitz, Clemens

    2008-10-15

    The ATP binding cassette (ABC) transporter LmrA from Lactococcus lactis transports cytotoxic molecules at the expense of ATP. Molecular and kinetic details of LmrA can be assessed by solid-state nuclear magnetic resonance (ssNMR), if functional reconstitution at a high protein-lipid ratio can be achieved and the kinetic rate constants are small enough. In order to follow ATP hydrolysis directly by 31P-magic angle spinning (MAS) nuclear magnetic resonance (NMR), we generated such conditions by reconstituting LmrA-dK388, a mutant with slower ATP turnover rate, at a protein-lipid ration of 1:150. By analysing time-resolved 31P spectra, protein activity has been directly assessed. These data demonstrate the general possibility to perform ssNMR studies on a fully active full length ABC transporter and also form the foundation for further kinetic studies on LmrA by NMR. PMID:18817774

  4. An NMR thermometer for cryogenic magic-angle spinning NMR: The spin-lattice relaxation of 127I in cesium iodide

    NASA Astrophysics Data System (ADS)

    Sarkar, Riddhiman; Concistrè, Maria; Johannessen, Ole G.; Beckett, Peter; Denning, Mark; Carravetta, Marina; al-Mosawi, Maitham; Beduz, Carlo; Yang, Yifeng; Levitt, Malcolm H.

    2011-10-01

    The accurate temperature measurement of solid samples under magic-angle spinning (MAS) is difficult in the cryogenic regime. It has been demonstrated by Thurber et al. (J. Magn. Reson., 196 (2009) 84-87) [10] that the temperature dependent spin-lattice relaxation time constant of 79Br in KBr powder can be useful for measuring sample temperature under MAS over a wide temperature range (20-296 K). However the value of T1 exceeds 3 min at temperatures below 20 K, which is inconveniently long. In this communication, we show that the spin-lattice relaxation time constant of 127I in CsI powder can be used to accurately measure sample temperature under MAS within a reasonable experimental time down to 10 K.

  5. 1H High Resolution Magic-Angle Coil Spinning (HR-MACS) - NMR Metabolic Profiling of whole Saccharomyces cervisiae cells: A Demonstrative Study

    NASA Astrophysics Data System (ADS)

    Wong, Alan; Boutin, Celine; Aguiar, Pedro

    2014-06-01

    The low sensitivity of Nuclear Magnetic Resonance (NMR) is its prime shortcoming compared to other analytical methods for metabolomic studies. It relies on large sample volume (30-50 µl for HR-MAS) for rich metabolic profiling, hindering high-throughput screening especially when the sample requires a labor-intensive preparation or is a sacred specimen. This is indeed the case for some living organisms. This study evaluates a 1H HR-MAS approach for metabolic profiling of small volume (250 nl) whole bacterial cells, Saccharomyces cervisiae, using an emerging micro-NMR technology: high-resolution magic-angle coil spinning (HR-MACS). As a demonstrative study for whole cells, we perform two independent metabolomics studies identifying the significant metabolites associated with osmotic stress and aging.

  6. 1H high resolution magic-angle coil spinning (HR-MACS) μNMR metabolic profiling of whole Saccharomyces cervisiae cells: a demonstrative study

    PubMed Central

    Wong, Alan; Boutin, Céline; Aguiar, Pedro M.

    2014-01-01

    The low sensitivity and thus need for large sample volume is one of the major drawbacks of Nuclear Magnetic Resonance (NMR) spectroscopy. This is especially problematic for performing rich metabolic profiling of scarce samples such as whole cells or living organisms. This study evaluates a 1H HR-MAS approach for metabolic profiling of small volumes (250 nl) of whole cells. We have applied an emerging micro-NMR technology, high-resolution magic-angle coil spinning (HR-MACS), to study whole Saccharomyces cervisiae cells. We find that high-resolution high-sensitivity spectra can be obtained with only 19 million cells and, as a demonstration of the metabolic profiling potential, we perform two independent metabolomics studies identifying the significant metabolites associated with osmotic stress and aging. PMID:24971307

  7. (1)H high resolution magic-angle coil spinning (HR-MACS) μNMR metabolic profiling of whole Saccharomyces cervisiae cells: a demonstrative study.

    PubMed

    Wong, Alan; Boutin, Céline; Aguiar, Pedro M

    2014-01-01

    The low sensitivity and thus need for large sample volume is one of the major drawbacks of Nuclear Magnetic Resonance (NMR) spectroscopy. This is especially problematic for performing rich metabolic profiling of scarce samples such as whole cells or living organisms. This study evaluates a (1)H HR-MAS approach for metabolic profiling of small volumes (250 nl) of whole cells. We have applied an emerging micro-NMR technology, high-resolution magic-angle coil spinning (HR-MACS), to study whole Saccharomyces cervisiae cells. We find that high-resolution high-sensitivity spectra can be obtained with only 19 million cells and, as a demonstration of the metabolic profiling potential, we perform two independent metabolomics studies identifying the significant metabolites associated with osmotic stress and aging. PMID:24971307

  8. In situ structural characterization of a recombinant protein in native Escherichia coli membranes with solid-state magic-angle-spinning NMR.

    PubMed

    Fu, Riqiang; Wang, Xingsheng; Li, Conggang; Santiago-Miranda, Adriana N; Pielak, Gary J; Tian, Fang

    2011-08-17

    The feasibility of using solid-state magic-angle-spinning NMR spectroscopy for in situ structural characterization of the LR11 (sorLA) transmembrane domain (TM) in native Escherichia coli membranes is presented. LR11 interacts with the human amyloid precursor protein (APP), a central player in the pathology of Alzheimer's disease. The background signals from E. coli lipids and membrane proteins had only minor effects on the LR11 TM resonances. Approximately 50% of the LR11 TM residues were assigned by using (13)C PARIS data. These assignments allowed comparisons of the secondary structure of the LR11 TM in native membrane environments and commonly used membrane mimics (e.g., micelles). In situ spectroscopy bypasses several obstacles in the preparation of membrane proteins for structural analysis and offers the opportunity to investigate how membrane heterogeneity, bilayer asymmetry, chemical gradients, and macromolecular crowding affect the protein structure. PMID:21774553

  9. Conformational dynamics of phenylene rings in poly(p-phenylene vinylene) as revealed by 13C magic-angle-spinning exchange nuclear magnetic resonance experiments

    NASA Astrophysics Data System (ADS)

    deAzevedo, E. R.; Franco, R. W. A.; Marletta, A.; Faria, R. M.; Bonagamba, T. J.

    2003-08-01

    Poly(p-phenylene vinylene) (PPV) has shown a great potential for electro-optical applications due to its electroluminescent and semiconducting properties. Such properties are directly related with the polymer chain conformation and dynamics. Then, it is important to understand in detail the local chain motions. In this work, three 13C solid-state magic-angle-spinning (MAS) exchange NMR techniques were used to study conformational dynamics of phenylene rings in PPV. The standard 2D MAS exchange experiment was used to identify exchange processes between equivalent and nonequivalent sites. Centerband-only detection of exchange (CODEX) experiments were applied to determine the amplitude of the phenylene ring flips and small-angle oscillations. Additionally, a new version of the CODEX technique, which allows for the selective observation of segments executing exchange between non-equivalent sites, is demonstrated and applied to determine the flipping fractions and the activation energies of the phenylene ring rotations. It was found that, at -15 °C, (26±3)% of the rings undergo 180° flips in the millisecond time scale, with average imprecision of (30±5)° and activation energies of (23±3) kJ/mol. Other (31±10)% of the rings perform only small-angle oscillations with an average amplitude of (9±2)°. These results corroborate previous experimental data and agree with recent ab initio calculations of potential energies barriers in phenylenevinylene oligomers.

  10. Magic Physics?

    ERIC Educational Resources Information Center

    Featonby, David

    2010-01-01

    This article examines several readily available "magic tricks" which base their "trickery" on physics principles, and questions the use of the word "magic" in the 21st century, both in popular children's science and in everyday language. (Contains 18 figures.)

  11. Creating Magic Squares.

    ERIC Educational Resources Information Center

    Lyon, Betty Clayton

    1990-01-01

    One method of making magic squares using a prolongated square is illustrated. Discussed are third-order magic squares, fractional magic squares, fifth-order magic squares, decimal magic squares, and even magic squares. (CW)

  12. A 19F NMR Study of Enzyme Activity

    NASA Astrophysics Data System (ADS)

    Peterman, Keith E.; Lentz, Kevin; Duncan, Jeffery

    1998-10-01

    This basic enzyme activity laboratory experiment demonstrates how 19F NMR can be used in biochemical studies and presents the advantages of 19F NMR over 1H NMR for studies of this nature. N-Trifluoroacetylglycine was selected as a commercially available model fluorine-tagged substrate that readily undergoes acylase I-catalyzed hydrolysis to produce trifluoroacetic acid and glycine. Progress of the reaction was monitored by following conversion of the trifluoroacetyl moiety peak of N-trifluoroacetylglycine to trifluoroacetic acid. The extent of hydrolysis was determined by comparing integrated ratios of the two 19F NMR peaks. A plot of percent hydrolysis versus enzyme concentration was used to calculate unit activity of the enzyme. This is a viable laboratory experiment for junior/senior-level courses in instrumental analytical chemistry, biochemistry, molecular biology, or spectroscopy.

  13. First evidences for 19F(α, p)22Ne at astrophysical energies

    NASA Astrophysics Data System (ADS)

    D’Agata, G.; Spitaleri, C.; Pizzone, R. G.; Blagus, S.; Figuera, P.; Grassi, L.; Guardo, G. L.; Gulino, M.; Hayakawa, S.; Indelicato, I.; Kshetri, R.; La Cognata, M.; Lamia, L.; Lattuada, M.; Mijatović, T.; Milin, M.; Miljanic, D.; Prepolec, L.; Sergi, M. L.; Skukan, N.; Soic, N.; Tokic, V.; Tumino, A.; Uroic, M.

    2016-04-01

    19F experimental abundances is overestimated in respect to the theoretical one: it is therefore clear that further investigations are needed. We focused on the 19F(α, p) 22 Ne reaction, representing the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct methods is E C.M. ≈ 0.91 MeV, while the Gamow region is between 0.39 ÷ 0.8 MeV, far below the Coulomb barrier (3.8 MeV). For this reason, an experiment at Rudjer Boskovic Institute (Zagreb) was performed, applying the Trojan Horse Method. Following this method we selected the quasi-free contribution coming from 6Li(19 F,p22 Ne)2 H at Ebeam=6 MeV at kinematically favourable angles, and the cross section at energies 0 < EC.M. < 1.4 MeV was extracted in arbitrary units, covering the astrophysical region of interest.

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

    SciTech Connect

    Thurber, Kent R. Tycko, Robert

    2014-05-14

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

  15. A Novel High-Resolution and Sensitivity-Enhanced Three-Dimensional Solid-State NMR Experiment Under Ultrafast Magic Angle Spinning Conditions.

    PubMed

    Zhang, Rongchun; Pandey, Manoj Kumar; Nishiyama, Yusuke; Ramamoorthy, Ayyalusamy

    2015-01-01

    Although magic angle spinning (MAS) solid-state NMR is a powerful technique to obtain atomic-resolution insights into the structure and dynamics of a variety of chemical and biological solids, poor sensitivity has severely limited its applications. In this study, we demonstrate an approach that suitably combines proton-detection, ultrafast-MAS and multiple frequency dimensions to overcome this limitation. With the utilization of proton-proton dipolar recoupling and double quantum (DQ) coherence excitation/reconversion radio-frequency pulses, very high-resolution proton-based 3D NMR spectra that correlate single-quantum (SQ), DQ and SQ coherences of biological solids have been obtained successfully for the first time. The proposed technique requires a very small amount of sample and does not need multiple radio-frequency (RF) channels. It also reveals information about the proximity between a spin and a certain other dipolar-coupled pair of spins in addition to regular SQ/DQ and SQ/SQ correlations. Although (1)H spectral resolution is still limited for densely proton-coupled systems, the 3D technique is valuable to study dilute proton systems, such as zeolites, small molecules, or deuterated samples. We also believe that this new methodology will aid in the design of a plethora of multidimensional NMR techniques and enable high-throughput investigation of an exciting class of solids at atomic-level resolution. PMID:26138791

  16. Microanisotropy imaging: quantification of microscopic diffusion anisotropy and orientational order parameter by diffusion MRI with magic-angle spinning of the q-vector

    NASA Astrophysics Data System (ADS)

    Lasič, Samo; Szczepankiewicz, Filip; Eriksson, Stefanie; Nilsson, Markus; Topgaard, Daniel

    2014-02-01

    Diffusion tensor imaging (DTI) is the method of choice for non-invasive investigations of the structure of human brain white matter. The results are conventionally reported as maps of the fractional anisotropy (FA), which is a parameter related to microstructural features such as axon density, diameter, and myelination. The interpretation of FA in terms of microstructure becomes ambiguous when there is a distribution of axon orientations within the image voxel. In this paper, we propose a procedure for resolving this ambiguity by determining a new parameter, the microscopic fractional anisotropy (µFA), which corresponds to the FA without the confounding influence of orientation dispersion. In addition, we suggest a method for measuring the orientational order parameter (OP) for the anisotropic objects. The experimental protocol is capitalizing on a recently developed diffusion NMR pulse sequence based on magic-angle spinning of the q-vector. Proof-of-principle experiments are carried out on microimaging and clinical MRI equipment using lyotropic liquid crystals and plant tissues as model materials with high µFA and low FA on account of orientation dispersion. We expect the presented method to be especially fruitful in combination with DTI and high angular resolution acquisition protocols for neuroimaging studies of grey and white matter.

  17. Systematic evaluation of heteronuclear spin decoupling in solid-state NMR at the rotary-resonance conditions in the regime of fast magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Sharma, Kshama; Madhu, P. K.; Agarwal, Vipin

    2016-09-01

    The performance of heteronuclear spin decoupling sequences in solid-state NMR severely degrades when the proton radiofrequency (RF) nutation frequencies (ν1) are close to or at multiples of magic-angle spinning (MAS) frequency (νr) that are referred to as rotary-resonance recoupling conditions (ν1 = n · νr). Recently, two schemes, namely, PISSARRO and rCWApA, have been shown to be less affected by the problem of MAS and RF interference, specifically at the n = 2 rotary-resonance recoupling condition, especially in the fast MAS regime. Here, we systematically evaluate the loss in intensity of several heteronuclear spin decoupling sequences at the n = 1, 2 conditions compared to high-power decoupling in the fast-MAS regime. We propose that in the fast-MAS regime (above 40 kHz) the entire discussion about RF and MAS interference can be avoided by using appropriate low-power decoupling sequences which give comparable performance to decoupling sequences with high-power 1H irradiation of ca.195 kHz.

  18. Metabolomics by Proton High-Resolution Magic-Angle-Spinning Nuclear Magnetic Resonance of Tomato Plants Treated with Two Secondary Metabolites Isolated from Trichoderma.

    PubMed

    Mazzei, Pierluigi; Vinale, Francesco; Woo, Sheridan Lois; Pascale, Alberto; Lorito, Matteo; Piccolo, Alessandro

    2016-05-11

    Trichoderma fungi release 6-pentyl-2H-pyran-2-one (1) and harzianic acid (2) secondary metabolites to improve plant growth and health protection. We isolated metabolites 1 and 2 from Trichoderma strains, whose different concentrations were used to treat seeds of Solanum lycopersicum. The metabolic profile in the resulting 15 day old tomato leaves was studied by high-resolution magic-angle-spinning nuclear magnetic resonance (HRMAS NMR) spectroscopy directly on the whole samples without any preliminary extraction. Principal component analysis (PCA) of HRMAS NMR showed significantly enhanced acetylcholine and γ-aminobutyric acid (GABA) content accompanied by variable amount of amino acids in samples treated with both Trichoderma secondary metabolites. Seed germination rates, seedling fresh weight, and the metabolome of tomato leaves were also dependent upon doses of metabolites 1 and 2 treatments. HRMAS NMR spectroscopy was proven to represent a rapid and reliable technique for evaluating specific changes in the metabolome of plant leaves and calibrating the best concentration of bioactive compounds required to stimulate plant growth. PMID:27088924

  19. Quantification of microheterogeneity in glioblastoma multiforme with ex vivo high-resolution magic-angle spinning (HRMAS) proton magnetic resonance spectroscopy.

    PubMed Central

    Cheng, L. L.; Anthony, D. C.; Comite, A. R.; Black, P. M.; Tzika, A. A.; Gonzalez, R. G.

    2000-01-01

    Microheterogeneity is a routinely observed neuropathologic characteristic in brain tumor pathology. Although microheterogeneity is readily documented by routine histologic techniques, these techniques only measure tumor status at the time of biopsy or surgery and do not indicate likely tumor progression. A biochemical screening technique calibrated against pathologic standards would greatly assist in predicting tumor progression from its biological activity. Here we demonstrate for the first time that proton magnetic resonance spectroscopy (1H MRS) with high-resolution magic-angle spinning (HRMAS), a technique introduced in 1997, can preserve tissue histopathologic features while producing well-resolved spectra of cellular metabolites in the identical intact tissue specimens. Observed biochemical alterations and tumor histopathologic characteristics can thus be correlated for the same surgical specimen, obviating the problems caused by tumor microheterogeneity. We analyzed multiple specimens of a single human glioblastoma multiforme surgically removed from a 44-year-old patient. Each specimen was first measured with HRMAS 1H MRS to determine tumor metabolites, then evaluated by quantitative histopathology. The concentrations of lactate and mobile lipids measured with HRMAS linearly reflected the percentage of tumor necrosis. Moreover, metabolic ratios of phosphorylcholine to choline correlated linearly with the percentage of the highly cellular malignant glioma. The quantification of tumor metabolic changes with HRMAS 1H MRS, in conjunction with subsequent histopathology of the same tumor specimen, has the potential to further our knowledge of the biochemistry of tumor heterogeneity during development, and thus ultimately to improve our accuracy in diagnosing, characterizing, and evaluating tumor progression. PMID:11303625

  20. Atomic-resolution structure of the CAP-Gly domain of dynactin on polymeric microtubules determined by magic angle spinning NMR spectroscopy.

    PubMed

    Yan, Si; Guo, Changmiao; Hou, Guangjin; Zhang, Huilan; Lu, Xingyu; Williams, John Charles; Polenova, Tatyana

    2015-11-24

    Microtubules and their associated proteins perform a broad array of essential physiological functions, including mitosis, polarization and differentiation, cell migration, and vesicle and organelle transport. As such, they have been extensively studied at multiple levels of resolution (e.g., from structural biology to cell biology). Despite these efforts, there remain significant gaps in our knowledge concerning how microtubule-binding proteins bind to microtubules, how dynamics connect different conformational states, and how these interactions and dynamics affect cellular processes. Structures of microtubule-associated proteins assembled on polymeric microtubules are not known at atomic resolution. Here, we report a structure of the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of dynactin motor on polymeric microtubules, solved by magic angle spinning NMR spectroscopy. We present the intermolecular interface of CAP-Gly with microtubules, derived by recording direct dipolar contacts between CAP-Gly and tubulin using double rotational echo double resonance (dREDOR)-filtered experiments. Our results indicate that the structure adopted by CAP-Gly varies, particularly around its loop regions, permitting its interaction with multiple binding partners and with the microtubules. To our knowledge, this study reports the first atomic-resolution structure of a microtubule-associated protein on polymeric microtubules. Our approach lays the foundation for atomic-resolution structural analysis of other microtubule-associated motors. PMID:26604305

  1. Proton-detected solid-state NMR spectroscopy of fully protonated proteins at slow to moderate magic-angle spinning frequencies

    NASA Astrophysics Data System (ADS)

    Mote, Kaustubh R.; Madhu, Perunthiruthy K.

    2015-12-01

    1H -detection offers a substitute to the sensitivity-starved experiments often used to characterize biomolecular samples using magic-angle spinning solid-state NMR spectroscopy (MAS-ssNMR). To mitigate the effects of the strong 1H -1H dipolar coupled network that would otherwise severely broaden resonances, high MAS frequencies (>40 kHz) are often employed. Here, we have explored the alternative of stroboscopic 1H -detection at moderate MAS frequencies of 5-30 kHz using windowed version of supercycled-phase-modulated Lee-Goldburg homonuclear decoupling. We show that improved resolution in the 1H dimension, comparable to that obtainable at high spinning frequencies of 40-60 kHz without homonuclear decoupling, can be obtained in these experiments for fully protonated proteins. Along with detailed analysis of the performance of the method on the standard tri-peptide f-MLF, experiments on micro-crystalline GB1 and amyloid- β aggregates are used to demonstrate the applicability of these pulse-sequences to challenging biomolecular systems. With only two parameters to optimize, broadbanded performance of the homonuclear decoupling sequence, linear dependence of the chemical-shift scaling factor on resonance offset and a straightforward implementation under experimental conditions currently used for many biomolecular studies (viz. spinning frequencies and radio-frequency amplitudes), we expect these experiments to complement the current 13C -detection based methods in assignments and characterization through chemical-shift mapping.

  2. Multidimensional High-Resolution Magic Angle Spinning and Solution-State NMR Characterization of (13)C-labeled Plant Metabolites and Lignocellulose.

    PubMed

    Mori, Tetsuya; Tsuboi, Yuuri; Ishida, Nobuhiro; Nishikubo, Nobuyuki; Demura, Taku; Kikuchi, Jun

    2015-01-01

    Lignocellulose, which includes mainly cellulose, hemicellulose, and lignin, is a potential resource for the production of chemicals and for other applications. For effective production of materials derived from biomass, it is important to characterize the metabolites and polymeric components of the biomass. Nuclear magnetic resonance (NMR) spectroscopy has been used to identify biomass components; however, the NMR spectra of metabolites and lignocellulose components are ambiguously assigned in many cases due to overlapping chemical shift peaks. Using our (13)C-labeling technique in higher plants such as poplar samples, we demonstrated that overlapping peaks could be resolved by three-dimensional NMR experiments to more accurately assign chemical shifts compared with two-dimensional NMR measurements. Metabolites of the (13)C-poplar were measured by high-resolution magic angle spinning NMR spectroscopy, which allows sample analysis without solvent extraction, while lignocellulose components of the (13)C-poplar dissolved in dimethylsulfoxide/pyridine solvent were analyzed by solution-state NMR techniques. Using these methods, we were able to unambiguously assign chemical shifts of small and macromolecular components in (13)C-poplar samples. Furthermore, using samples of less than 5 mg, we could differentiate between two kinds of genes that were overexpressed in poplar samples, which produced clearly modified plant cell wall components. PMID:26143886

  3. Multidimensional High-Resolution Magic Angle Spinning and Solution-State NMR Characterization of 13C-labeled Plant Metabolites and Lignocellulose

    PubMed Central

    Mori, Tetsuya; Tsuboi, Yuuri; Ishida, Nobuhiro; Nishikubo, Nobuyuki; Demura, Taku; Kikuchi, Jun

    2015-01-01

    Lignocellulose, which includes mainly cellulose, hemicellulose, and lignin, is a potential resource for the production of chemicals and for other applications. For effective production of materials derived from biomass, it is important to characterize the metabolites and polymeric components of the biomass. Nuclear magnetic resonance (NMR) spectroscopy has been used to identify biomass components; however, the NMR spectra of metabolites and lignocellulose components are ambiguously assigned in many cases due to overlapping chemical shift peaks. Using our 13C-labeling technique in higher plants such as poplar samples, we demonstrated that overlapping peaks could be resolved by three-dimensional NMR experiments to more accurately assign chemical shifts compared with two-dimensional NMR measurements. Metabolites of the 13C-poplar were measured by high-resolution magic angle spinning NMR spectroscopy, which allows sample analysis without solvent extraction, while lignocellulose components of the 13C-poplar dissolved in dimethylsulfoxide/pyridine solvent were analyzed by solution-state NMR techniques. Using these methods, we were able to unambiguously assign chemical shifts of small and macromolecular components in 13C-poplar samples. Furthermore, using samples of less than 5 mg, we could differentiate between two kinds of genes that were overexpressed in poplar samples, which produced clearly modified plant cell wall components. PMID:26143886

  4. Recoupling of native homonuclear dipolar couplings in magic-angle-spinning solid-state NMR by the double-oscillating field technique

    NASA Astrophysics Data System (ADS)

    Straasø, Lasse Arnt; Nielsen, Niels Chr.

    2010-08-01

    A new solid-state NMR method, the double-oscillating field technique (DUO), that under magic-angle-spinning conditions produces an effective Hamiltonian proportional to the native high-field homonuclear dipole-dipole coupling operator is presented. The method exploits one part of the radio frequency (rf) field to recouple the dipolar coupling interaction with a relatively high scaling factor and to eliminate offset effects over a reasonable bandwidth while in the recoupling frame, the other part gives rise to a sufficiently large longitudinal component of the residual rf field that averages nonsecular terms and in addition ensures stability toward rf inhomogeneity and rf miscalibration. The capability of the DUO experiment to mediate transfer of polarization is described theoretically and compared numerically and experimentally with finite pulse rf driven recoupling and experimentally with dipolar-assisted rotational resonance. Two-dimensional recoupling experiments were performed on antiparallel amyloid fibrils of the decapeptide SNNFGAILSS with the FGAIL fragment uniformly labeled with C13 and N15.

  5. Magic Angle Spinning NMR Reveals Sequence-Dependent Structural Plasticity, Dynamics, and the Spacer Peptide 1 Conformation in HIV-1 Capsid Protein Assemblies

    SciTech Connect

    Han, Yun; Hou, Guangjin; Suiter, Christopher L.; Ahn, Jinwoo; Byeon, In-Ja L.; Lipton, Andrew S.; Burton, Sarah D.; Hung, Ivan; Gorkov, Peter L.; Gan, Zhehong; Brey, William W.; Rice, David M.; Gronenborn, Angela M.; Polenova, Tatyana E.

    2013-11-27

    Maturation of HIV-1 virus into an infectious virion requires cleavage of the Gag polyprotein into its constituent domains and formation of a conical capsid core that encloses viral RNA and a small complement of proteins for replication. The final step of this process is the cleavage of the SP1 peptide from the CA-SP1 maturation intermediate, which triggers the condensation of the CA protein into a conical capsid. The mechanism of this step, including the conformation of the SP1 peptide in CA-SP1, is under intense debate. In this report, we examine the tubular assemblies of CA and the CA-SP1 maturation intermediate using Magic Angle Spinning NMR spectroscopy. At the magnetic fields of 19.9 T and above, tubular CA and CA-SP1 assemblies yield outstanding-quality 2D and 3D MAS NMR spectra, which are amenable to resonance assignments and detailed structural characterization. Dipolar- and scalar-based correlation experiments unequivocally indicate that SP1 peptide is in a random coil conformation and mobile in the assembled CA-SP1. Analysis of two sequence variants reveals that remarkably, the conformation of SP1 tail, of the functionally important CypA loop, and of the loop preceding helix 8 are sequence dependent and modulated by the residue variations at distal sites. These findings challenge the role of SP1 as a conformational switch in the maturation process and establish sequence-dependent conformational plasticity in CA.

  6. Systematic evaluation of heteronuclear spin decoupling in solid-state NMR at the rotary-resonance conditions in the regime of fast magic-angle spinning.

    PubMed

    Sharma, Kshama; Madhu, P K; Agarwal, Vipin

    2016-09-01

    The performance of heteronuclear spin decoupling sequences in solid-state NMR severely degrades when the proton radiofrequency (RF) nutation frequencies (ν1) are close to or at multiples of magic-angle spinning (MAS) frequency (νr) that are referred to as rotary-resonance recoupling conditions (ν1=n·νr). Recently, two schemes, namely, PISSARRO and rCW(ApA), have been shown to be less affected by the problem of MAS and RF interference, specifically at the n=2 rotary-resonance recoupling condition, especially in the fast MAS regime. Here, we systematically evaluate the loss in intensity of several heteronuclear spin decoupling sequences at the n=1, 2 conditions compared to high-power decoupling in the fast-MAS regime. We propose that in the fast-MAS regime (above 40kHz) the entire discussion about RF and MAS interference can be avoided by using appropriate low-power decoupling sequences which give comparable performance to decoupling sequences with high-power (1)H irradiation of ca.195kHz. PMID:27472380

  7. Cross-Correlated Relaxation of Dipolar Coupling and Chemical-Shift Anisotropy in Magic-Angle Spinning R1ρ NMR Measurements: Application to Protein Backbone Dynamics Measurements.

    PubMed

    Kurauskas, Vilius; Weber, Emmanuelle; Hessel, Audrey; Ayala, Isabel; Marion, Dominique; Schanda, Paul

    2016-09-01

    Transverse relaxation rate measurements in magic-angle spinning solid-state nuclear magnetic resonance provide information about molecular motions occurring on nanosecond-to-millisecond (ns-ms) time scales. The measurement of heteronuclear ((13)C, (15)N) relaxation rate constants in the presence of a spin-lock radiofrequency field (R1ρ relaxation) provides access to such motions, and an increasing number of studies involving R1ρ relaxation in proteins have been reported. However, two factors that influence the observed relaxation rate constants have so far been neglected, namely, (1) the role of CSA/dipolar cross-correlated relaxation (CCR) and (2) the impact of fast proton spin flips (i.e., proton spin diffusion and relaxation). We show that CSA/D CCR in R1ρ experiments is measurable and that the CCR rate constant depends on ns-ms motions; it can thus provide insight into dynamics. We find that proton spin diffusion attenuates this CCR due to its decoupling effect on the doublet components. For measurements of dynamics, the use of R1ρ rate constants has practical advantages over the use of CCR rates, and this article reveals factors that have so far been disregarded and which are important for accurate measurements and interpretation. PMID:27500976

  8. A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

    NASA Astrophysics Data System (ADS)

    Martel, L.; Somers, J.; Berkmann, C.; Koepp, F.; Rothermel, A.; Pauvert, O.; Selfslag, C.; Farnan, I.

    2013-05-01

    A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (˜10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th1-xUx)O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first 17O MAS-NMR measurements on NpO2+x samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.

  9. Cross-polarization magic-angle spinning nuclear magnetic resonance study of platinum complexes containing the cis-P2PtC2 fragment.

    PubMed

    Challoner, R; Sebald, A

    1995-01-01

    31P and 195Pt cross-polarization magic-angle spinning nuclear magnetic resonance (CP-MAS NMR) spectra of three platinum complexes of formal oxidation state Pt(0) and Pt(II), respectively, are reported. All three complexes, (Ph3P)2Pt(C2H4) (1), (Et2P-CH2-CH2-PEt2)Pt(C identical to C-H)2 (2) and (Ph2P-CH2-CH2-PPh2)Pt(C identical to C-C(CH3)=CH2)2 (3) contain the square-planar cis-P2PtC2 fragment and show unusual NMR spectroscopic properties insofar that the 195Pt shielding patterns are fairly narrow in relation to what one would generally have to expect for 195Pt in square-planar coordination. Another unexpected NMR property of the cis-P2PtC2 fragment in 1-3 is the absence of spinning frequency-dependent second-order effects in this solid-state ABX spin system. PMID:7894980

  10. Recoupling of chemical shift anisotropies in solid-state NMR under high-speed magic-angle spinning and in uniformly 13C-labeled systems

    NASA Astrophysics Data System (ADS)

    Chan, Jerry C. C.; Tycko, Robert

    2003-05-01

    We demonstrate the possibility of recoupling chemical shift anisotropy (CSA) interactions in solid-state nuclear magnetic resonance (NMR) under high-speed magic-angle spinning (MAS) while retaining a static CSA powder pattern line shape and simultaneously attenuating homonuclear dipole-dipole interactions. CSA recoupling is accomplished by a rotation-synchronized radio-frequency pulse sequence with symmetry properties that permit static CSA line shapes to be obtained. We suggest a specific recoupling sequence, which we call ROCSA, for which the scaling factors for CSA and homonuclear dipole-dipole interactions are 0.272 and approximately 0.05, respectively. This sequence is suitable for high-speed 13C MAS NMR experiments on uniformly 13C-labeled organic compounds, including biopolymers. We demonstrate the ROCSA sequence experimentally by measuring the 13C CSA patterns of the uniformly labeled, polycrystalline compounds L-alanine and N-acetyl-D,L-valine at MAS frequencies of 11 and 20 kHz. We also present experimental data for amyloid fibrils formed by a 15-residue fragment of the β-amyloid peptide associated with Alzheimer's disease, in which four amino acid residues are uniformly labeled, demonstrating the applicability to biochemical systems of high molecular weight and significant complexity. Analysis of the CSA patterns in the amyloid fibril sample demonstrates the utility of ROCSA measurements as probes of peptide and protein conformation in noncrystalline solids.

  11. High-resolution 1H NMR in solids with multiple-pulse sequences and magic-angle sample spinning at 270 MHz

    NASA Astrophysics Data System (ADS)

    Scheler, G.; Haubenreisser, U.; Rosenberger, H.

    A probe suitable for 270-MHz 1H NMR in solids is described, using the combination of the phase-error-compensated WAHUHA multiple-pulse cycle and magic-angle sample spinning (MAS). The experimental results obtained at this frequency are compared with measurements at 60 MHz. Because of the increase of frequency the spectral resolution is improved by a factor of about 5. For a variety of organic and inorganic substances the resolution varies from 0.3 ppm in polycrystalline adamantane to about 2 ppm, sufficient to resolve resonance signals of protons of different molecular groups, such as NH 3, NH 4, olefinic, aromatic, and aliphatic protons. Averaged chemical shifts of a series of selected hydrogen-bonded powder samples are discussed. The residual linewidths were found to be due predominantly to second-order residual dipolar broadening, the cross term between resonance offset and dipolar interaction, nonresolved chemical shifts, and interactions of protons with nuclei which have a strong quadrupolar moment. The resolution is expected to be increased by combining the high-field MAS experiments and more effective multiple-pulse sequences, e.g., the 24-pulse cycle developed recently by Burum and Rhim.

  12. High-Speed Magic-Angle Spinning 13C MAS NMR Spectra of Adamantane: Self-Decoupling of the Heteronuclear Scalar Interaction and Proton Spin Diffusion

    NASA Astrophysics Data System (ADS)

    Ernst, Matthias; Verhoeven, Aswin; Meier, Beat H.

    1998-02-01

    We have investigated the carbon line shape of solid adamantane under high-speed magic-angle sample spinning (MAS) acquired without proton decoupling. The CH-group shows a spinning-speed-dependent line broadening while the CH2-group consists of a spinning-speed-independent sharp component and a spinning-speed-dependent broader part. These phenomena can be explained by self-decoupling of theJ-interaction due to proton spin diffusion. Such a self-decoupling process can be described by a magnetization exchange process between the multiplet lines. Changing the spin-diffusion rate constant by off-resonance irradiation of the protons allows us to observe the full range from slow exchange to coalescence to fast exchange of the carbon spectra. One of the multiplet components in the CH2-group corresponds to a group spin of the protons of zero and therefore does not couple to the other protons. This gives rise to the sharp central line. The magnetization exchange rate constant between the different multiplet lines can be determined from the spectra and is a measure for the spinning-speed-dependent proton spin-diffusion rate constant. Even at an MAS speed of 30 kHz, proton spin diffusion is still observable despite the relatively weak intermolecular proton dipolar-coupling network in adamantane which results in a static proton line width of only 14 kHz (full width at half height).

  13. Magic angle Lee-Goldburg frequency offset irradiation improves the efficiency and selectivity of SPECIFIC-CP in triple-resonance MAS solid-state NMR

    PubMed Central

    Wu, C.H.; De Angelis, Anna A.; Opella, Stanley J.

    2014-01-01

    The efficiency and selectivity of SPECIFIC-CP, a widely used method for selective double cross-polarization in triple-resonance magic angle spinning solid-state NMR, is improved by performing the tangential-shaped 13C irradiation at an offset frequency that meets the Lee-Goldburg condition (LG-SPECIFIC-CP). This is demonstrated on polycrystalline samples of uniformly 13C, 15N labeled N-acetyl-leucine and N-formyl-Met-Leu-Phe-OH (MLF) at 700 MHz and 900 MHz 1H resonance frequencies, respectively. For the single 13Cα of N-acetyl-leucine, relative to conventional broad band cross-polarization, the SPECIFIC-CP signal has 47% of the intensity. Notably, the LG-SPECIFIC-CP signal has 72% of the intensity, essentially the theoretical maximum. There were no other changes in the experimental parameters. The three 13Cα signals in MLF show some variation in intensities, reflecting the relatively narrow bandwidth of a frequency-offset procedure, and pointing to future developments for this class of experiment. PMID:25051542

  14. A Monte Carlo/Simulated Annealing Algorithm for Sequential Resonance Assignment in Solid State NMR of Uniformly Labeled Proteins with Magic-Angle Spinning

    PubMed Central

    Tycko, Robert; Hu, Kan-Nian

    2010-01-01

    We describe a computational approach to sequential resonance assignment in solid state NMR studies of uniformly 15N,13C-labeled proteins with magic-angle spinning. As input, the algorithm uses only the protein sequence and lists of 15N/13Cα crosspeaks from 2D NCACX and NCOCX spectra that include possible residue-type assignments of each crosspeak. Assignment of crosspeaks to specific residues is carried out by a Monte Carlo/simulated annealing algorithm, implemented in the program MC_ASSIGN1. The algorithm tolerates substantial ambiguity in residue-type assignments and coexistence of visible and invisible segments in the protein sequence. We use MC_ASSIGN1 and our own 2D spectra to replicate and extend the sequential assignments for uniformly labeled HET-s(218-289) fibrils previously determined manually by Siemer et al. (J. Biomolec. NMR, vol. 34, pp. 75-87, 2006) from a more extensive set of 2D and 3D spectra. Accurate assignments by MC_ASSIGN1 do not require data that are of exceptionally high quality. Use of MC_ASSIGN1 (and its extensions to other types of 2D and 3D data) is likely to alleviate many of the difficulties and uncertainties associated with manual resonance assignments in solid state NMR studies of uniformly labeled proteins, where spectral resolution and signal-to-noise are often sub-optimal. PMID:20547467

  15. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: The importance of level crossings

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2012-01-01

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

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

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2014-01-01

    We report solid state 13C and 1H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1H and cross-polarized 13C NMR signals from 15N,13C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations. PMID:24832263

  17. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

  18. The molecular origin of a loading-induced black layer in the deep region of articular cartilage at the magic angle

    PubMed Central

    Wang, Nian; Kahn, David; Badar, Farid; Xia, Yang

    2014-01-01

    Purpose To investigate the molecular origin of an unusual low-intensity layer in the deep region of articular cartilage as seen in MRI when the tissue is imaged under compression and oriented at the magic angle. Materials and Methods Microscopic MRI (μMRI) T2 and T1ρ experiments were carried out for both native and degraded (treated with trypsin) 18 specimens. The glycosaminoglycan (GAG) concentrations in the specimens were quantified by both sodium ICP-OES and μMRI Gd(DTPA)2--contrast methods. The mechanical modulus of the specimens was also measured. Results Native tissue shows no load-induced layer, while the trypsin-degraded tissue shows clearly the low-intensity line at the deep part of tissue. The GAG reductions are confirmed by the sodium ICP-OES (from 81.7 ± 5.4 mg/ml to 9.2 ± 3.4 mg/ml), MRI GAG quantification (from 72.4 ± 6.7 mg/ml to 11.2 ± 2.9 mg/ml). The modulus reduction is confirmed by biomechanics (from 4.3 ± 0.7 MPa to 0.3 ± 0.1 MPa). Conclusion Both T2 and T1ρ profiles in native and degraded cartilage show strongly strain-, depth-, and angle-dependent using high resolution MRI. The GAG reduction is responsible for the visualization of a low-intensity layer in deep cartilage when it is loaded and orientated at 55°. PMID:24833266

  19. Characterization of 19A-like 19F pneumococcal isolates from Papua New Guinea and Fiji

    PubMed Central

    Dunne, E.M.; Tikkanen, L.; Balloch, A.; Gould, K.; Yoannes, M.; Phuanukoonnon, S.; Licciardi, P.V.; Russell, F.M.; Mulholland, E.K.; Satzke, C.; Hinds, J.

    2015-01-01

    Molecular identification of Streptococcus pneumoniae serotype 19F is routinely performed by PCR targeting the wzy gene of the capsular biosynthetic locus. However, 19F isolates with genetic similarity to 19A have been reported in the United States and Brazil. We screened 78 pneumococcal carriage isolates and found six 19F wzy variants that originated from children in Papua New Guinea and Fiji. Isolates were characterized using multilocus sequence typing and opsonophagocytic assays. The 19F wzy variants displayed similar susceptibility to anti-19F IgG antibodies compared to standard 19F isolates. Our findings indicate that these 19F variants may be more common than previously believed. PMID:26339490

  20. Menu Magic!

    ERIC Educational Resources Information Center

    Smith, Susan H.; Hickey, Bethany

    2003-01-01

    Describes the activity "Menu Magic!" that helps eighth graders review the power of adjectives. Notes that students "eat up this project" that promises to deliver the opportunity to analyze, synthesize, and evaluate while giving students the chance to work in cooperative groups. Describes and gives examples of the "Menu Magic" project. (SG)

  1. A High-Resolution 3D Separated-Local-Field Experiment by Means of Magic-Angle Turning

    PubMed

    Hu; Alderman; Pugmire; Grant

    1997-05-01

    A 3D separated-local-field (SLF) experiment based on the 2D PHORMAT technique is described. In the 3D experiment, the conventional 2D SLF powder pattern for each chemically inequivalent carbon is separated according to their different isotropic chemical shifts. The dipolar coupling constant of a C-H pair, hence the bond distance, and the relative orientation of the chemical-shift tensor to the C-H vector can all be determined for the protonated carbons with a single measurement. As the sample turns at only about 30 Hz in a MAT experiment, the SLF patterns obtained approach those of a stationary sample, and an accuracy in the measurement similar to that obtained on a stationary sample is expected. The technique is demonstrated on 2,6-dimethoxynaphthalene, where the 13 C-1 H separated-local-field powder patterns for the six chemically inequivalent carbons are clearly identified and measured. The observed dipolar coupling for the methoxy carbon is effectively reduced by the fast rotation of the group about its C3 symmetry axis. The average angle between the C-H bond direction and the C3 rotation axis in the OCH3 group is found to be about 66°. PMID:9252281

  2. In vivo 19F MRI and 19F MRS of 19F-labelled boronophenylalanine fructose complex on a C6 rat glioma model to optimize boron neutron capture therapy (BNCT)

    NASA Astrophysics Data System (ADS)

    Porcari, Paola; Capuani, Silvia; D'Amore, Emanuela; Lecce, Mario; La Bella, Angela; Fasano, Fabrizio; Campanella, Renzo; Migneco, Luisa Maria; Saverio Pastore, Francesco; Maraviglia, Bruno

    2008-12-01

    Boron neutron capture therapy (BNCT) is a promising binary modality used to treat malignant brain gliomas. To optimize BNCT effectiveness a non-invasive method is needed to monitor the spatial distribution of BNCT carriers in order to estimate the optimal timing for neutron irradiation. In this study, in vivo spatial distribution mapping and pharmacokinetics evaluation of the 19F-labelled boronophenylalanine (BPA) were performed using 19F magnetic resonance imaging (19F MRI) and 19F magnetic resonance spectroscopy (19F MRS). Characteristic uptake of 19F-BPA in C6 glioma showed a maximum at 2.5 h after compound infusion as confirmed by both 19F images and 19F spectra acquired on blood samples collected at different times after infusion. This study shows the ability of 19F MRI to selectively map the bio-distribution of 19F-BPA in a C6 rat glioma model, as well as providing a useful method to perform pharmacokinetics of BNCT carriers.

  3. Fluorine (19F) MRS and MRI in biomedicine

    PubMed Central

    Ruiz-Cabello, Jesús; Barnett, Brad P.; Bottomley, Paul A.; Bulte, Jeff W.M.

    2011-01-01

    Shortly after the introduction of 1H MRI, fluorinated molecules were tested as MR-detectable tracers or contrast agents. Many fluorinated compounds, which are nontoxic and chemically inert, are now being used in a broad range of biomedical applications, including anesthetics, chemotherapeutic agents, and molecules with high oxygen solubility for respiration and blood substitution. These compounds can be monitored by fluorine (19F) MRI and/or MRS, providing a noninvasive means to interrogate associated functions in biological systems. As a result of the lack of endogenous fluorine in living organisms, 19F MRI of ‘hotspots’ of targeted fluorinated contrast agents has recently opened up new research avenues in molecular and cellular imaging. This includes the specific targeting and imaging of cellular surface epitopes, as well as MRI cell tracking of endogenous macrophages, injected immune cells and stem cell transplants. PMID:20842758

  4. Characterization of the ground X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F

    SciTech Connect

    Mawhorter, Richard J.; Murphy, Benjamin S.; Baum, Alexander L.; Sears, Trevor J.; Yang, T.; Rupasinghe, P. M; McRaven, C. P.; Shafer-Ray, N. E.; Alphei, Lukas D.; Grabow, Jens-Uwe

    2011-08-15

    Pure rotational spectra of the ground electronic-vibrational X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F are measured with a resonator pulsed supersonic jet Fourier-transform microwave spectrometer. Also reported is a new measurement of the Stark effect on the optical spectra of A(leftarrow)X{sub 1} transitions. These spectra are combined with published high-resolution infrared spectra of X{sub 2}{r_reversible}X{sub 1} transitions in order to create a complete picture of the ground state of lead monofluoride. For the microwave data, molecules are prepared by laser ablation of lead target rods and stabilized in a supersonic jet of neon mixed with sulfur hexafluoride. For the optical Stark spectra, a continuous source of molecules is created in a nozzle heated to 1000 deg. C. The microwave spectra confirm, improve, and extend previously reported constants that describe the rotational, spin-orbit, and hyperfine interactions of the ground electronic state of the PbF molecule. A discrepancy concerning the sign of the hyperfine constant describing the {sup 207}Pb nucleus is discussed. Magnetic-field-dependent microwave spectra are used to characterize the Zeeman interaction in terms of two g factors of the body-fixed electronic wave function. The optical Stark spectra are used to characterize the electric dipole moment of the X{sub 1} and A states.

  5. Characterization of high-tannin fractions from humus by carbon-13 cross-polarization and magic-angle spinning nuclear magnetic resonance.

    PubMed

    Lorenz, Klaus; Preston, Caroline M

    2002-01-01

    Condensed tannins can be found in various parts of many plants. Unlike lignin there has been little study of their fate as they enter the soil organic matter pool and their influence on nutrient cycling, especially through their protein-binding properties. We extracted and characterized tannin-rich fractions from humus collected in 1998 from a black spruce [Picea mariana (Mill.) Britton et al.] forest in Canada where a previous study (1995) showed high levels (3.8% by weight) of condensed tannins. A reference tannin purified from black spruce needles was characterized by solution 13C nuclear magnetic resonance (NMR) as a pure procyanidin with mainly cis stereochemistry and an average chain length of four to five units. The colorimetric proanthocyanidin (PA) assay, standardized against the black spruce tannin, showed that both extracted humus fractions had higher tannin contents than the original humus (2.84% and 11.17% vs. 0.08%), and accounted for 32% of humus tannin content. Consistent with the results from the chemical assay, the aqueous fraction showed higher tannin signals in the 13C cross-polarization and magic-angle spinning (CPMAS) NMR spectrum than the emulsified one. As both tannin-rich humus fractions were depleted in N and high in structures derived from lignin and cutin, they did not have properties consistent with recaldtrant tannin-protein complexes proposed as a mechanism for N sequestration in humus. Further studies are needed to establish if tannin-protein structures in humus can be detected or isolated, or if tannins contribute to forest management problems observed in these ecosystems by binding to and slowing down the activity of soil enzymes. PMID:11931430

  6. Magic Angle Spinning Nuclear Magnetic Resonance Characterization of Voltage-Dependent Anion Channel Gating in Two-Dimensional Lipid Crystalline Bilayers

    PubMed Central

    2015-01-01

    The N-terminus of the voltage-dependent anion channel (VDAC) has been proposed to contain the mechanistically important gating helices that modulate channel opening and closing. In this study, we utilize magic angle spinning nuclear magnetic resonance (MAS NMR) to determine the location and structure of the N-terminus for functional channels in lipid bilayers by measuring long-range 13C–13C distances between residues in the N-terminus and other domains of VDAC reconstituted into DMPC lipid bilayers. Our structural studies show that the distance between A14 Cβ in the N-terminal helix and S193 Cβ is ∼4–6 Å. Furthermore, VDAC phosphorylation by a mitochondrial kinase at residue S193 has been claimed to delay mitochondrial cell death by causing a conformational change that closes the channel, and a VDAC-Ser193Glu mutant has been reported to show properties very similar to those of phosphorylated VDAC in a cellular context. We expressed VDAC-S193E and reconstituted it into DMPC lipid bilayers. Two-dimensional 13C–13C correlation experiments showed chemical shift perturbations for residues located in the N-terminus, indicating possible structural perturbations to that region. However, electrophysiological data recorded on VDAC-S193E showed that channel characteristics were identical to those of wild type samples, indicating that phosphorylation of S193 does not directly affect channel gating. The combination of NMR and electrophysiological results allows us to discuss the validity of proposed gating models. PMID:25545271

  7. Selective excitation enables assignment of proton resonances and (1)H-(1)H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy.

    PubMed

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of (1)H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as (13)C or (15)N. In this method, after the initial preparation of proton magnetization and cross-polarization to (13)C nuclei, transverse magnetization of desired (13)C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific (13)C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of (1)H-(1)H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids. PMID:26203019

  8. Analysis of metabolic characteristics in a rat model of chronic pancreatitis using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy.

    PubMed

    Tian, Bing; Ma, Chao; Wang, Jian; Pan, Chun-Shu; Yang, Gen-Jin; Lu, Jian-Ping

    2015-01-01

    Pathological and metabolic alterations co-exist and co-develop in the progression of chronic pancreatitis (CP). The aim of the present study was to investigate the metabolic characteristics and disease severity of a rat model of CP in order to determine associations in the observed pathology and the metabolites of CP using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR). Wistar rats (n=36) were randomly assigned into 6 groups (n=6 per group). CP was established by administering dibutyltin dichloride solution into the tail vein. After 0, 7, 14, 21, 28 and 35 days, the pancreatic tissues were collected for pathological scoring or for HR-MAS NMR. Correlation analyses between the major pathological scores and the integral areas of the major metabolites were determined. The most representative metabolites, aspartate, betaine and fatty acids, were identified as possessing the greatest discriminatory significance. The Spearman's rank correlation coefficients between the pathology and metabolites of the pancreatic tissues were as follows: Betaine and fibrosis, 0.454 (P=0.044); betaine and inflammatory cell infiltration, 0.716 (P=0.0001); aspartate and fibrosis, -0.768 (P=0.0001); aspartate and inflammatory cell infiltration, -0.394 (P=0.085); fatty acid and fibrosis, -0.764 (P=0.0001); and fatty acid and inflammatory cell infiltration, -0.619 (P=0.004). The metabolite betaine positively correlated with fibrosis and inflammatory cell infiltration in CP. In addition, aspartate negatively correlated with fibrosis, but exhibited no significant correlation with inflammatory cell infiltration. Furthermore, the presence of fatty acids negatively correlated with fibrosis and inflammatory cell infiltration in CP. HR-MAS NMR may be used to analyze metabolic characteristics in a rat model of different degrees of chronic pancreatitis. PMID:25338744

  9. A Large Sample Volume Magic Angle Spinning Nuclear Magnetic Resonance Probe for In-Situ Investigations with Constant Flow of Reactants

    SciTech Connect

    Hu, Jian Z.; Sears, Jesse A.; Mehta, Hardeep S.; Ford, Joseph J.; Kwak, Ja Hun; Zhu, Kake; Wang, Yong; Liu, Jun; Hoyt, David W.; Peden, Charles HF

    2012-02-21

    A large-sample-volume constant-flow magic angle sample spinning (CF-MAS) NMR probe is reported for in-situ studies of the reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions. In our approach, the reactants are introduced into the catalyst bed using a fixed tube at one end of the MAS rotor while a second fixed tube, linked to a vacuum pump, is attached at the other end of the rotor. The pressure difference between both ends of the catalyst bed inside the sample cell space forces the reactants flowing through the catalyst bed, which improves the diffusion of the reactants and products. This design allows the use of a large sample volume for enhanced sensitivity and thus permitting in-situ 13C CF-MAS studies at natural abundance. As an example of application, we show that reactants, products and reaction transition states associated with the 2-butanol dehydration reaction over a mesoporous silicalite supported heteropoly acid catalyst (HPA/meso-silicalite-1) can all be detected in a single 13C CF-MAS NMR spectrum at natural abundance. Coke products can also be detected at natural 13C abundance and under the stopped flow condition. Furthermore, 1H CF-MAS NMR is used to identify the surface functional groups of HPA/meso-silicalite-1 under the condition of in-situ drying . We also show that the reaction dynamics of 2-butanol dehydration using HPA/meso-silicalite-1 as a catalyst can be explored using 1H CF-MAS NMR.

  10. Selective excitation enables assignment of proton resonances and 1H-1H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-01

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of 1H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as 13C or 15N. In this method, after the initial preparation of proton magnetization and cross-polarization to 13C nuclei, transverse magnetization of desired 13C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific 13C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of 1H-1H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  11. Selective excitation enables assignment of proton resonances and {sup 1}H-{sup 1}H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    SciTech Connect

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of {sup 1}H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as {sup 13}C or {sup 15}N. In this method, after the initial preparation of proton magnetization and cross-polarization to {sup 13}C nuclei, transverse magnetization of desired {sup 13}C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific {sup 13}C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of {sup 1}H-{sup 1}H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  12. Assessment of a 1H high-resolution magic angle spinning NMR spectroscopy procedure for free sugars quantification in intact plant tissue.

    PubMed

    Delgado-Goñi, Teresa; Campo, Sonia; Martín-Sitjar, Juana; Cabañas, Miquel E; San Segundo, Blanca; Arús, Carles

    2013-08-01

    In most plants, sucrose is the primary product of photosynthesis, the transport form of assimilated carbon, and also one of the main factors determining sweetness in fresh fruits. Traditional methods for sugar quantification (mainly sucrose, glucose and fructose) require obtaining crude plant extracts, which sometimes involve substantial sample manipulation, making the process time-consuming and increasing the risk of sample degradation. Here, we describe and validate a fast method to determine sugar content in intact plant tissue by using high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR). The HR-MAS NMR method was used for quantifying sucrose, glucose and fructose in mesocarp tissues from melon fruits (Cucumis melo var. reticulatus and Cucumis melo var. cantalupensis). The resulting sugar content varied among individual melons, ranging from 1.4 to 7.3 g of sucrose, 0.4-2.5 g of glucose; and 0.73-2.83 g of fructose (values per 100 g fw). These values were in agreement with those described in the literature for melon fruit tissue, and no significant differences were found when comparing them with those obtained using the traditional, enzymatic procedure, on melon tissue extracts. The HR-MAS NMR method offers a fast (usually <30 min) and sensitive method for sugar quantification in intact plant tissues, it requires a small amount of tissue (typically 50 mg fw) and avoids the interferences and risks associated with obtaining plant extracts. Furthermore, this method might also allow the quantification of additional metabolites detectable in the plant tissue NMR spectrum. PMID:23824526

  13. High-resolution magic angle spinning and 1H magnetic resonance spectroscopy reveal significantly altered neuronal metabolite profiles in CLN1 but not in CLN3.

    PubMed

    Sitter, Beathe; Autti, Taina; Tyynelä, Jaana; Sonnewald, Ursula; Bathen, Tone F; Puranen, Johanna; Santavuori, Pirkko; Haltia, Matti J; Paetau, Anders; Polvikoski, Tuomo; Gribbestad, Ingrid S; Häkkinen, Anna-Maija

    2004-09-01

    The neuronal ceroid lipofuscinoses (NCLs) are among the most severe inherited progressive neurodegenerative disorders of children. The purpose of this study was to compare the in vivo 1.5-T 1H magnetic resonance (MR) and ex vivo 14.3-T high-resolution (HR) magic angle spinning (MAS) 1H MR brain spectra of patients with infantile (CLN1) and juvenile (CLN3) types of NCL, to obtain detailed information about the alterations in the neuronal metabolite profiles in these diseases and to test the suitability of the ex vivo HR MAS (1)H MRS technique in analysis of autopsy brain tissue. Ex vivo spectra from CLN1 autopsy brain tissue (n = 9) significantly differed from those of the control (n = 9) and CLN3 (n = 5) groups, although no differences were found between the CLN3 and the control groups. Principal component analysis of ex vivo data showed that decreased levels of N-acetylaspartate (NAA), gamma-aminobutyric acid (GABA), glutamine, and glutamate as well as increased levels of inositols characterized the CLN1 spectra. Also, the intensity ratio of lipid methylene/methyl protons was decreased in spectra of CLN1 brain tissue compared with CLN3 and control brain tissue. In concordance with the ex vivo data, the in vivo spectra of late-stage patients with CLN1 (n = 3) revealed a dramatic decrease of NAA and a proportional increase of myo-inositol and lipids compared with control subjects. Again, the spectra of patients with CLN3 (n = 13) did not differ from those of controls (n = 15). In conclusion, the ex vivo and in vivo spectroscopic findings were in good agreement within all analyzed groups and revealed significant alterations in metabolite profiles in CLN1 brain tissue but not in CLN3 compared with controls. Furthermore, HR MAS 1H MR spectra facilitated refined detection of neuronal metabolites, including GABA, and composition of lipids in the autopsy brain tissue of NCL patients. PMID:15352223

  14. Carbon-13 cross-polarization magic-angle-spinning nuclear magnetic resonance investigation of the interactions between maleic anhydride grafted polypropylene and wood polymers.

    PubMed

    Rude, Erica; Laborie, Marie-Pierre G

    2008-05-01

    The chemical interactions between maleic anhydride grafted polypropylene (MAPP) and wood were studied with solid-state carbon-13 cross-polarization magic-angle-spinning nuclear magnetic resonance ((13)C CPMAS NMR) spectroscopy. MAPP was synthesized with 100% (13)C enrichment at the C(1) and C(4) carbons to allow detection of the [1,4-(13)C(2)]MAPP functional groups and was melt blended with cellulose, lignin, and maple wood. In the cellulose/MAPP blend, changes in (13)C CPMAS NMR corrected signal intensities for the anhydride and dicarboxylic maleic acid functionalities suggested that esterification may have occurred predominantly from the more numerous diacid carbons. A single proton longitudinal relaxation in the rotating frame, (H)T(1rho), for the MAPP and the cellulose carbons in the blend suggested that they were spin coupled, i.e., homogeneous on a 10-200 Angstrom scale. Esterification was also suggested in the lignin/MAPP blend. Furthermore, the more significant changes in the intensities of the carbonyl signals and (H)T(1rho) values suggested that lignin may be more reactive to MAPP than cellulose. Finally, when maple was melt blended with MAPP, the same trends in the (13)C CP-MAS NMR spectra and (H)T(1rho) behavior were observed as when MAPP was blended with cellulose or lignin. This study therefore clarifies that during melt compounding of wood with MAPP, esterification occurs with wood polymers, preferentially with lignin. Understanding the interactions of MAPP with wood is of significance for the development of natural-fiber-reinforced thermoplastic composites. PMID:18498698

  15. Magic angle spinning nuclear magnetic resonance characterization of voltage-dependent anion channel gating in two-dimensional lipid crystalline bilayers.

    PubMed

    Eddy, Matthew T; Andreas, Loren; Teijido, Oscar; Su, Yongchao; Clark, Lindsay; Noskov, Sergei Y; Wagner, Gerhard; Rostovtseva, Tatiana K; Griffin, Robert G

    2015-02-01

    The N-terminus of the voltage-dependent anion channel (VDAC) has been proposed to contain the mechanistically important gating helices that modulate channel opening and closing. In this study, we utilize magic angle spinning nuclear magnetic resonance (MAS NMR) to determine the location and structure of the N-terminus for functional channels in lipid bilayers by measuring long-range (13)C-(13)C distances between residues in the N-terminus and other domains of VDAC reconstituted into DMPC lipid bilayers. Our structural studies show that the distance between A14 Cβ in the N-terminal helix and S193 Cβ is ∼4-6 Å. Furthermore, VDAC phosphorylation by a mitochondrial kinase at residue S193 has been claimed to delay mitochondrial cell death by causing a conformational change that closes the channel, and a VDAC-Ser193Glu mutant has been reported to show properties very similar to those of phosphorylated VDAC in a cellular context. We expressed VDAC-S193E and reconstituted it into DMPC lipid bilayers. Two-dimensional (13)C-(13)C correlation experiments showed chemical shift perturbations for residues located in the N-terminus, indicating possible structural perturbations to that region. However, electrophysiological data recorded on VDAC-S193E showed that channel characteristics were identical to those of wild type samples, indicating that phosphorylation of S193 does not directly affect channel gating. The combination of NMR and electrophysiological results allows us to discuss the validity of proposed gating models. PMID:25545271

  16. Enhanced sensitivity and resolution in (1)H solid-state NMR spectroscopy of paramagnetic complexes under very fast magic angle spinning.

    PubMed

    Wickramasinghe, Nalinda P; Shaibat, Medhat; Ishii, Yoshitaka

    2005-04-27

    High-resolution NMR spectroscopy for paramagnetic complexes in solids has been rarely performed because of its limited sensitivity and resolution due to large paramagnetic shifts and associated technical difficulties. The present study demonstrates that magic angle spinning (MAS) at speeds exceeding 20 kHz provides unusually high sensitivity and excellent resolution in 1H solid-state NMR (SSNMR) for paramagnetic systems. Spinning-speed dependence of 1H MAS spectra showed that very fast MAS (VFMAS) at 24-28 kHz enhanced sensitivity by a factor of 12-18, compared with the sensitivity of 1H SSNMR spectra under moderate MAS at 10 kHz, for Cu(dl-alanine)2.H2O and Mn(acac)3, for which the spectral ranges due to 1H paramagnetic shifts reach 200 and 1000 ppm, respectively. It was theoretically and experimentally confirmed that the absolute sensitivity of 1H VFMAS for small paramagnetic complexes such as Cu(dl-alanine)2 can be an order of magnitude higher than that of equimolar diamagnetic ligands because of short 1H T1 ( approximately 1 ms) of the paramagnetic systems and improved sensitivity under VFMAS. On the basis of this demonstrated high sensitivity, 1H SSNMR micro analysis of paramagnetic systems in a nanomole scale is proposed. Applications were performed on two polymorphs of Cu(II)(8-quinolinol)2, which is a suppressor of human cancer cells. It was demonstrated that 1H VFMAS SSNMR spectra accumulated for 20 nmol of the polycrystalline samples in 10 min enabled one to distinguish alpha- and beta-forms of Cu(II)(8-quinolinol)2 on the basis of shift positions and line widths. PMID:15839671

  17. Application of the Floquet theory to multiple quantum NMR of dipolar-coupled multi-spin systems under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Filip, Claudiu; Bertmer, Marko; Demco, Dan E.; Blümich, Bernhard

    A new analytical Liouville-space representation of the time-propagator under magic angle spinning (MAS) is introduced using the formalized quantum Floquet theory. This approach has the advantage that it is applicable to the analysis of any type of NMR experiment where MAS is combined with multiple-pulse excitation. General relationships describing the spectral parameters in multiple-quantum (MQ) MAS spectra are derived in this representation. Their use is illustrated with an application to double-quantum (DQ) NMR spectra of dipolarcoupled multi-spin systems. Corresponding to the separation of the MAS time-propagator into a rotor modulated and a dephasing component, two distinct mechanisms for DQ excitation are identified. One of them exploits the rotor-modulated component to excite DQ coherences through dipolar-recoupling techniques, which are familiar for spin pairs. Analytical expressions of the integral intensities and linewidths in the resulting DQ sideband pattern are derived in the form of power series expansions of the inverse rotor frequency, of which coefficients depend on structural parameters. In a multi-spin system they can most reliably be extracted in the fast spinning regime. The other mechanism exploits the dephasing component, which is characteristic to multi-spin systems only. This is shown to give rise to DQ coherences by free evolution at full rotor periods. The possibility to exploit it for selective excitation of higher order MQ coherences is discussed. In either case, the dephasing component also leads to residual broadening. The main results of the theoretical developments are demonstrated experimentally on adamantane.

  18. Magic-angle spinning NMR study of deuterium site occupancy and dynamics in ZrNiD1.0 and ZrNiD3.0

    NASA Astrophysics Data System (ADS)

    Adolphi, Natalie L.; Badola, Sharwari; Browder, Lisa A.; Bowman, R. C.

    2002-01-01

    Both static and magic-angle spinning (MAS) 2H nuclear magnetic resonance spectroscopy indicate that two inequivalent sites are occupied in ZrNiD3.0, in a 2:1 ratio, in agreement with previous work. The sites occupied in the trihydride phase have been previously identified as Zr3Ni and Zr3Ni2. In ZrNiD1.0, two well-resolved lines of equal intensity are observed in the MAS spectrum at temperatures<220 K, indicating that two other inequivalent sites are occupied in a 1:1 ratio, in contrast with previous reports that only one type of site (Zr4Ni2) is occupied in the monohydride (β) phase at room temperature and above. The temperature dependences of both MAS and static ZrNiD1.0 spectra indicate that no phase transitions occur over the entire temperature range studied, 160-500 K. The deuterium hopping rate in ZrNiD1.0 is determined from characteristic changes in the MAS spectra as a function of temperature; the motion is consistent with an activation energy Ea≅0.44 eV assuming a rate prefactor 1/τ0~1013 s-1. In ZrNiD3.0, the rate of deuterium motion is determined from signatures of motion in the static and MAS spectra. The motion in ZrNiD3.0 is consistent with an activation energy Ea≅0.62 eV assuming a rate prefactor of ~1013 s-1.

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  20. High-resolution aluminum-27 solid-state magic-angle sample-spinning nuclear magnetic resonance spectroscopic study of AlCl sub 3 -tetrahydrofuran complexes

    SciTech Connect

    Han, Oc Hee; Oldfield, E. )

    1990-09-19

    The authors have obtained {sup 27}Al solid-state nuclear magnetic resonance (NMR) spectra of several AlCl{sub 3}-THF complexes, using magic-angle sample-spinning (MASS) NMR at high field. The authors results suggest that the isotropic chemical shifts ({delta}{sub i}) occur in relatively well defined regions for 4-, 5-, and 6-coordinate species (AlCl{sub 4}{sup {minus}}, {approximately} 103 ppm; AlCl{sub 3}{center dot}THF, {approximately} 99 ppm; trans-AlCl{sub 3}{center dot}2THF, {approximately} 60 ppM; trans-(AlCl{sub 2}(THF){sub 4}){sup +}, {approximately} 14 ppM), as found previously with aluminum oxo compounds. They also find that theoretically calculated average nuclear quadrupole coupling constants (e{sup 2}qQ/h) (trans-(AlCl{sub 2}(THF){sub 4}){sup +}, {approximately} 6.3 MHz; trans-AlCl{sub 3}{center dot}2THF, {approximately} 4.6 MHz; AlCl{sub 3}{center dot}THF, {approximately} 3.0 MHz; AlCl{sub 4}{sup {minus}}, 0 MHz) are in good accord with experimentally determined nuclear quadrupole coupling constants, determined from computer simulations of the MASS NMR spectra (trans-(AlCl{sub 2}(THF){sub 4}){sup +}, 6.4 MHz; trans-AlCl{sub 3}{center dot}2THF, 4.9 MHz; AlCl{sub 3}{center dot}THF, 4.7 MHz; AlCl{sub 4}{sup {minus}}, 0.3 MHz). Both {sup 27}Al {delta}{sub i} and e{sup 2}qQ/h determinations appear to be useful as probes of structure in these systems, and thus offer a facile means of monitoring various solid-state reactions. 14 refs., 3 figs., 3 tabs.

  1. Angular distributions and cross-sections of projectile-like fragments in the 19F + 159Tb reaction

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Tripathi, R.; Sodaye, S.; Sudarshan, K.; Pujari, P. K.

    2013-01-01

    The angular distribution of projectile-like fragments (PLFs) in the 19F + 159Tb reaction have been measured at beam energy equal to 98MeV. Angular distributions of PLFs showed a systematic change with increasing mass transfer, starting from the peaking at grazing angle for heavier PLFs to very forward peaked angular distributions for lighter PLFs. Cross-sections of the different PLFs were obtained by integrating their centre-of-mass angular distributions. The PLF cross-sections have been compared with the incomplete fusion cross-sections obtained from the earlier measurement of the evaporation residue cross-section. Reduced cross-sections for lighter PLFs were observed to be higher compared to those observed in 19F + 66Zn reaction at similar values of E cm/ V b. Also, elastic scattering measurements were carried out to get information about the grazing angle and total reaction cross-section.

  2. Voltage Controlled Geometric Phase Rotation in ^{208}Pb^{19}F.

    NASA Astrophysics Data System (ADS)

    Furneaux, J. E.; Shafer-Ray, Neil; Coker, J.; Rupasinghe, P. M.; McRaven, C. P.

    2013-06-01

    Many theoretical publications have investigated the impact of the geometric phase on measurements of the e-EDM. However, there has been surprisingly little quantitative comparison of these models with experiment. Here we create a quantum beat experiment that starts with an optical pump and ends with an optical probe of ^{208}Pb^{19}F. This measurement includes the ability to control a geometric phase variation of the molecular alignment by applying an appropriate bias voltage. These experiments will then used to test the accuracy of our model calculations of geometric phase rotation.

  3. Comparisons of lipid dynamics and packing in fully interdigitated monoarachidoylphosphatidylcholine and non-interdigitated dipalmitoylphosphatidylcholine bilayers: cross polarization/magic angle spinning 13C-NMR studies.

    PubMed

    Wu, W G; Chi, L M

    1990-07-24

    13C-NMR spectra have been obtained at 50.3 MHz for monoarachidoylphosphatidylcholine (MAPC) and dipalmitoylphosphatidylcholine (DPPC) dispersions from 25 degrees C to 55 degrees C and for DPPC polycrystals at 25 degrees C using the cross polarization/magic angle spinning technique. Differential scanning calorimetric studies on DPPC and MAPC dispersions show comparable lipid phase transitions with transition temperatures at 41 degrees C and 45 degrees C, respectively, and thus enable the comparison of thermal, structural and dynamic differences between these two systems at corresponding temperatures. Conformational-dependent 13C chemical shift studies on DPPC dispersions demonstrate not only the coexistence of the tilted gel (L beta') and liquid-crystalline (L alpha) phases in the rippled gel (P beta') phase, but also the presence of an intermediate third microscopic phase as evidenced by three resolvable peaks for omega - 1 methylene carbon signals at the temperature interval between Tp and Tm. By comparing chemical shifts of MAPC in the hydrocarbon chain region with those of DPPC at similar reduced temperatures, it can be concluded that the packings are perturbed markedly in the middle segment of the fatty acyl chain during the lamellar to micellar transition. However, terminal methylene and methyl groups of interdigitated MAPC lamellae were found to be more ordered than those of non-interdigitated DPPC bilayers in the gel state. Interestingly, the terminal methyl groups of MAPC in the micelles remain to be relatively ordered; in fact, they are more ordered than the corresponding acyl chain end of DPPC in the liquid-crystalline state. Analysis of data obtained from rotating frame proton spin-lattice relaxation measurements shows a highly mobile phosphocholine headgroup, a rigid carbonyl group and an ordered hydrocarbon chain for lamellar MAPC in the interdigitated state. Furthermore, results suggest that free rotations of the glycerol C2-C3 bond within MAPC

  4. Site-resolved multiple-quantum filtered correlations and distance measurements by magic-angle spinning NMR: Theory and applications to spins with weak to vanishing quadrupolar couplings.

    PubMed

    Eliav, U; Haimovich, A; Goldbourt, A

    2016-01-14

    We discuss and analyze four magic-angle spinning solid-state NMR methods that can be used to measure internuclear distances and to obtain correlation spectra between a spin I = 1/2 and a half-integer spin S > 1/2 having a small quadrupolar coupling constant. Three of the methods are based on the heteronuclear multiple-quantum and single-quantum correlation experiments, that is, high rank tensors that involve the half spin and the quadrupolar spin are generated. Here, both zero and single-quantum coherence of the half spins are allowed and various coherence orders of the quadrupolar spin are generated, and filtered, via active recoupling of the dipolar interaction. As a result of generating coherence orders larger than one, the spectral resolution for the quadrupolar nucleus increases linearly with the coherence order. Since the formation of high rank tensors is independent of the existence of a finite quadrupolar interaction, these experiments are also suitable to materials in which there is high symmetry around the quadrupolar spin. A fourth experiment is based on the initial quadrupolar-driven excitation of symmetric high order coherences (up to p = 2S, where S is the spin number) and subsequently generating by the heteronuclear dipolar interaction higher rank (l + 1 or higher) tensors that involve also the half spins. Due to the nature of this technique, it also provides information on the relative orientations of the quadrupolar and dipolar interaction tensors. For the ideal case in which the pulses are sufficiently strong with respect to other interactions, we derive analytical expressions for all experiments as well as for the transferred echo double resonance experiment involving a quadrupolar spin. We show by comparison of the fitting of simulations and the analytical expressions to experimental data that the analytical expressions are sufficiently accurate to provide experimental (7)Li-(13)C distances in a complex of lithium, glycine, and water. Discussion

  5. Magic-angle spinning NMR studies of molecular organization in multibilayers formed by 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine.

    PubMed Central

    Halladay, H N; Stark, R E; Ali, S; Bittman, R

    1990-01-01

    Magic-angle spinning 1H and 13C nuclear magnetic resonance (NMR) have been employed to study 50%-by-weight aqueous dispersions of 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine (C[18]:C[10]PC) and 1-octadecanoyl-2-d19-decanoyl-PC (C[18]:C[10]PC-d19), mixed-chain phospholipids which can form interdigitated multibilayers. The 1H NMR linewidth for methyl protons of the choline headgroup has been used to monitor the liquid crystalline-to-gel (LC-to-G) phase transition and confirm variations between freezing and melting temperatures. Both 1H and 13C spin-lattice relaxation times indicate unusual restrictions on segmental reorientation at megahertz frequencies for C(18):C(10)PC as compared with symmetric-chain species in the LC state; nevertheless each chemical moiety of the mixed-chain phospholipid exhibits motional behavior that may be classified as liquidlike. Two-dimensional nuclear Overhauser spectroscopy (NOESY) on C(18):C(10)PC and C(18):C(10)PC-d19 reveals cross-peaks between the omega-methyl protons of the C18 chain and the N-methyl protons of the phosphocholine headgroup, and several experimental and theoretical considerations argue against an interpretation based on spin diffusion. Using NMR relaxation times and NOESY connectivities along with a computational formalism for four-spin systems (Keepers, J. W., and T. L. James. 1984. J. Magn. Reson. 57:404-426), an estimate of 3.5 A is obtained for the average distance between the omega-methyl protons of the C18 chain and the N-methyl protons of the phosphocholine headgroup. This finding is consistent with a degree of interdigitation similar to that proposed for organized assemblies of gel-state phosphatidylcholine molecules with widely disparate acyl-chain lengths (Hui, S. W., and C.-H. Huang. 1986. Biochemistry. 25:1330-1335); however, acyl-chain bendback or other intermolecular interactions may also contribute to the NOESY results. For multibilayers of C(18):C(10)PC in the gel phase, 13C chemical

  6. Sensitivity enhanced (14)N/(14)N correlations to probe inter-beta-sheet interactions using fast magic angle spinning solid-state NMR in biological solids.

    PubMed

    Pandey, Manoj Kumar; Amoureux, Jean-Paul; Asakura, Tetsuo; Nishiyama, Yusuke

    2016-08-10

    (14)N/(14)N correlations are vital for structural studies of solid samples, especially those in which (15)N isotopic enrichment is challenging, time-consuming and expensive. Although (14)N nuclei have high isotopic abundance (99.6%), there are inherent difficulties in observing (14)N/(14)N correlations due to limited resolution and sensitivity related to: (i) low (14)N gyromagnetic ratio (γ), (ii) large (14)N quadrupolar couplings, (iii) integer (14)N spin quantum number (I = 1), and (iv) very weak (14)N-(14)N dipolar couplings. Previously, we demonstrated a proton-detected 3D (14)N/(14)N/(1)H correlation experiment at fast magic angle spinning (MAS) on l-histidine·HCl·H2O utilizing a through-bond (J) and residual dipolar-splitting (RDS) based heteronuclear multiple quantum correlation (J-HMQC) sequence mediated through (1)H/(1)H radio-frequency driven recoupling (RFDR). As an extension of our previous work, in this study we show the utility of dipolar-based HMQC (D-HMQC) in combination with (1)H/(1)H RFDR mixing to obtain sensitivity enhanced (14)N/(14)N correlations in more complex biological solids such as a glycyl-l-alanine (Gly-l-Ala) dipeptide, and parallel (P) and antiparallel (AP) β-strand alanine tripeptides (P-(Ala)3 and AP-(Ala)3, respectively). These systems highlight the mandatory necessity of 3D (14)N/(14)N/(1)H measurements to get (14)N/(14)N correlations when the amide proton resonances are overlapped. Moreover, the application of long selective (14)N pulses, instead of short hard ones, is shown to improve the sensitivity. Globally, we demonstrate that replacing J-scalar with dipolar interaction and hard- with selective-(14)N pulses allows gaining a factor of ca. 360 in experimental time. On the basis of intermolecular NH/NH distances and (14)N quadrupolar tensor orientations, (14)N/(14)N correlations are effectively utilized to make a clear distinction between the parallel and antiparallel arrangements of the β-strands in (Ala)3 through the

  7. Modified polysaccharides as potential (19)F magnetic resonance contrast agents.

    PubMed

    Krawczyk, Tomasz; Minoshima, Masafumi; Sugihara, Fuminori; Kikuchi, Kazuya

    2016-06-16

    The introduction of 3-aminobenzotrifluoride into partially oxidized alginic acid, dextran, and polygalacturonic acid (10-100 kDa) by means of the imine formation and a subsequent reduction resulted in water-soluble materials containing 1-14% of fluorine. They showed a single or split (19)F NMR signal in a narrow range of -63 to -63.5 ppm. The observed T1 and T2 were approximately 1 and 0.2 s at 400 or 500 MHz instruments, respectively. The samples showed low toxicity and uptake toward the HeLa cells similar to native polysaccharides and were preferentially localized in lysosomes. A tail intravenous injection of 5 mg of modified dextran containing 1% of fluorine revealed that the probe was not trapped in liver, spleen or kidneys, but was quickly cleared with urine. The proposed materials can be used for imaging of the gastrointestinal tract or the genitourinary system and act as a material for more complex (19)F MRI agent synthesis. PMID:27148998

  8. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose

    NASA Astrophysics Data System (ADS)

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental C13 cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of C13 nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed.

  9. STATISTICAL ANALYSIS OF TANK 19F FLOOR SAMPLE RESULTS

    SciTech Connect

    Harris, S.

    2010-09-02

    Representative sampling has been completed for characterization of the residual material on the floor of Tank 19F as per the statistical sampling plan developed by Harris and Shine. Samples from eight locations have been obtained from the tank floor and two of the samples were archived as a contingency. Six samples, referred to in this report as the current scrape samples, have been submitted to and analyzed by SRNL. This report contains the statistical analysis of the floor sample analytical results to determine if further data are needed to reduce uncertainty. Included are comparisons with the prior Mantis samples results to determine if they can be pooled with the current scrape samples to estimate the upper 95% confidence limits (UCL95%) for concentration. Statistical analysis revealed that the Mantis and current scrape sample results are not compatible. Therefore, the Mantis sample results were not used to support the quantification of analytes in the residual material. Significant spatial variability among the current scrape sample results was not found. Constituent concentrations were similar between the North and South hemispheres as well as between the inner and outer regions of the tank floor. The current scrape sample results from all six samples fall within their 3-sigma limits. In view of the results from numerous statistical tests, the data were pooled from all six current scrape samples. As such, an adequate sample size was provided for quantification of the residual material on the floor of Tank 19F. The uncertainty is quantified in this report by an UCL95% on each analyte concentration. The uncertainty in analyte concentration was calculated as a function of the number of samples, the average, and the standard deviation of the analytical results. The UCL95% was based entirely on the six current scrape sample results (each averaged across three analytical determinations).

  10. Magic Mirrors

    ERIC Educational Resources Information Center

    Mills, Allan

    2011-01-01

    "Magic mirrors" were so named because, when they were positioned to throw a reflected patch of sunlight on a nearby wall, this area contained an outline of a design cast on the back of the (bronze) mirror. Investigations begun in the 19th century showed that this was a response to heavy localized pressures exerted on the face of the thin mirror…

  11. Mummies & Magic.

    ERIC Educational Resources Information Center

    Casey, Jeanne E.

    1989-01-01

    Covers the cultural and aesthetic significance of Egyptian mummies, as explained in an exhibition at Boston's Museum of Fine Arts. The display, "Mummies & Magic: The Funerary Arts of Ancient Egypt," allowed for restoration work which did much to advance modern knowledge of Egyptian culture and funerary art. (LS)

  12. Magical Boxes

    ERIC Educational Resources Information Center

    Costello, Judith

    2005-01-01

    Students get excited when they realize that they can transform a flat sheet of paper into a box. By using different sizes of paper, they can make different sizes of boxes and put a box inside a box, inside a box. These magical boxes within boxes can contain unwanted emotions or special treasures. The project described in this article incorporates…

  13. Matisse Magic.

    ERIC Educational Resources Information Center

    Gibson, Marcia

    2002-01-01

    Presents an art lesson in which kindergarten and first-grade students learn about Henri Matisse and his art work. Explains that the students use "Model Magic" to create Matisse style face refrigerator magnets. Discusses in detail how to create the magnets. (CMK)

  14. Lifetime-parameters for quasi elastic and deep inelastic collisions extracted from complete angular distributions of89Y(19F, x) y reactions

    NASA Astrophysics Data System (ADS)

    Suomijärvi, T.; Lucas, R.; Mermaz, M. C.; Coffin, J.-P.; Guillaume, G.; Heusch, B.; Jundt, F.; Rami, F.

    1985-09-01

    Energy spectra and angular distributions of heavy fragments produced in 19F + 89Y reaction at 140 MeV incident energy have been measured. Two different domains of reaction mechanism are observed at forward and backward angles respectively; the corresponding lifetime parameters are extracted from their angular distributions.

  15. (19)F-MRI for monitoring human NK cells in vivo.

    PubMed

    Bouchlaka, Myriam N; Ludwig, Kai D; Gordon, Jeremy W; Kutz, Matthew P; Bednarz, Bryan P; Fain, Sean B; Capitini, Christian M

    2016-05-01

    The availability of clinical-grade cytokines and artificial antigen-presenting cells has accelerated interest in using natural killer (NK) cells as adoptive cellular therapy (ACT) for cancer. One of the technological shortcomings of translating therapies from animal models to clinical application is the inability to effectively and non-invasively track these cells after infusion in patients. We have optimized the nonradioactive isotope fluorine-19 ((19)F) as a means to label and track NK cells in preclinical models using magnetic resonance imaging (MRI). Human NK cells were expanded with interleukin (IL)-2 and labeled in vitro with increasing concentrations of (19)F. Doses as low as 2 mg/mL (19)F were detected by MRI. NK cell viability was only decreased at 8 mg/mL (19)F. No effects on NK cell cytotoxicity against K562 leukemia cells were observed with 2, 4 or 8 mg/mL (19)F. Higher doses of (19)F, 4 mg/mL and 8 mg/mL, led to an improved (19)F signal by MRI with 3 × 10(11) (19)F atoms per NK cell. The 4 mg/mL (19)F labeling had no effect on NK cell function via secretion of granzyme B or interferon gamma (IFNγ), compared to NK cells exposed to vehicle alone. (19)F-labeled NK cells were detectable immediately by MRI after intratumoral injection in NSG mice and up to day 8. When (19)F-labeled NK cells were injected subcutaneously, we observed a loss of signal through time at the site of injection suggesting NK cell migration to distant organs. The (19)F perfluorocarbon is a safe and effective reagent for monitoring the persistence and trafficking of NK cell infusions in vivo, and may have potential for developing novel imaging techniques to monitor ACT for cancer. PMID:27467963

  16. Through-space (19) F-(15) N couplings for the assignment of stereochemistry in flubenzimine.

    PubMed

    Ghiviriga, Ion; Rubinski, Miles A; Dolbier, William R

    2016-07-01

    Through-space (19) F-(15) N couplings revealed the configuration of flubenzimine, with the CF3 group on N4 pointing towards the lone pair of N5. The (19) F-(15) N coupling constants were measured at natural abundance using a spin-state selective indirect-detection pulse sequence. As (15) N-labelled proteins are routinely synthesized for NMR studies, through-space (19) F-(15) N couplings have the potential to probe the stereochemistry of these proteins by (19) F labelling of some amino acids or can reveal the site of docking of fluorine-containing drugs. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27059012

  17. {sup 19}F NMR spectra and structures of halogenated porphyrins

    SciTech Connect

    Birnbaum, E.R.; Hodge, J.A.; Grinstaff, M.W.

    1995-07-05

    Fluorine-19 NMR spectra of a series of halogenated porphyrins have been used to create a spectral library of different types of fluorine splitting patterns for tetrakis(pentafluorophenyl) porphyrins (TFPP) complexed with diamagnetic and paramagnetic metal ions. The paramagnetic shift, line broadening, and fine structure of the resonances form the peripheral pentafluorophenyl rings are dependent on the symmetry and core environment of the porphyrin macrocycles. In combination with crystal structure data, {sup 19}F NMR helps define the behavior of halogenated porphyrins in solution. Six new crystal structures for TFPP and octahalo-TFPP derivatives are reported: H{sub 2}TFPP in rhombohedral space group R3, a = 20.327(4) {Angstrom}, c = 15.261(2) {Angstrom}, {beta} = 103.87(2){degrees}, V = 2227.6(13) {Angstrom}{sup 3}, Z = 2; CuTFPP in rhombohedral space group R3, a = 20.358(5), c = 14.678(2) {Angstrom}, {alpha} = 88.97(1), {beta}=76.05(1){degrees}, {gamma} = 71.29(1){degrees}, V = 2181.4(6) {Angstrom}{sup 3}, Z = 2; ZnTFPPCl{sub 8} in tetragonal space group P42, c, a = 19.502(20), c = 10.916(8) {Angstrom}, V = 4152(6) {Angstrom}{sup 3}, Z = 2; H{sub 2}TFPPBr{sub 8} in monoclinic space group C2, a = 27.634(6) {Angstrom}, b = 6.926(2) {Angstrom}, c = 14.844(3) {Angstrom}, {beta} = 109.64(2){degrees}, V = 2675.8(11) {Angstrom}{sup 3}, Z = 2.

  18. Ring current shifts in (19)F-NMR of membrane proteins.

    PubMed

    Liu, Dongsheng; Wüthrich, Kurt

    2016-05-01

    Fluorine-19 NMR markers are attractive reporter groups for use in studies of complex biomacromolecular systems, in particular also for studies of function-related conformational equilibria and rate processes in membrane proteins. Advantages of (19)F-NMR probes include high sensitivity of the (19)F chemical shifts to variations in the non-covalent environment. Nonetheless, in studies of G protein-coupled receptors (GPCR) we encountered situations where (19)F chemical shifts were not responsive to conformational changes that had been implicated by other methods. This prompted us to examine possible effects of aromatic ring current fields on the chemical shifts of (19)F-NMR probes used in GPCRs. Analysis of previously reported (19)F-NMR data on the β2-adrenergic receptor and mammalian rhodopsin showed that all (19)F-labeling sites which manifested conformational changes are located near aromatic residues. Although ring current effects are small when compared to other known non-covalent effects on (19)F chemical shifts, there is thus an indication that their contributions are significant when studying activation processes in GPCRs, since the observed activation-related (19)F-NMR chemical shifts are comparable in size to the calculated ring current shifts. Considering the impact of ring current shifts may thus be helpful in identifying promising indigenous or engineered labeling sites for future (19)F-NMR studies of GPCR activation, and novel information may be obtained on the nature of conformational rearrangements near the (19)F-labels. It will then also be interesting to see if the presently indicated role of ring current shifts in membrane protein studies with (19)F-NMR markers can be substantiated by a more extensive data base resulting from future studies. PMID:27240587

  19. Study of the ferroelastic phase transition in the tetraethylammonium compound [N(C2H5)4]2ZnBr4 by magic-angle spinning and static NMR

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran

    2016-03-01

    The ferroelastic phase transition of tetraethylammonium compound [N(C2H5)4]2ZnBr4 at the phase transition temperature (TC) = 283 K was characterized by magic-angle spinning (MAS) and static nuclear magnetic resonance (NMR), and confirmed by optical polarizing spectroscopy. The structural geometry near TC was studied in terms of the chemical shifts and the spin-lattice relaxation times T1ρ in the rotating frame for 1H MAS NMR and 13C cross-polarization (CP)/MAS NMR. The two inequivalent ethyl groups were distinguishable in the 13C NMR spectrum, and the T1ρ results indicate that they undergo tumbling motion above TC in a coupled manner. From the 14N NMR results, the two nitrogen nuclei in the N(C2H5)4+ ions were distinguishable above TC, and the splitting in the spectra below TC was related to the ferroelastic domains with different orientations.

  20. A study of conformational stability of poly(L-alanine), poly(L-valine), and poly(L-alanine)/poly(L-valine) blends in the solid state by (13)C cross-polarization/magic angle spinning NMR.

    PubMed

    Murata, Katsuyoshi; Kuroki, Shigeki; Kimura, Hideaki; Ando, Isao

    2002-06-01

    13C cross-polarization/magic angle spinning (CP/MAS) NMR and (1)H T(1rho) experiments of poly(L-alanine) (PLA), poly(L-valine) (PLV), and PLA/PLV blends have been carried out in order to elucidate the conformational stability of the polypeptides in the solid state. These were prepared by adding a trifluoroacetic acid (TFA) solution of the polymer with a 2.0 wt/wt % of sulfuric acid (H(2)SO(4)) to alkaline water. From these experimental results, it is clarified that the conformations of PLA and PLV in their blends are strongly influenced by intermolecular hydrogen-bonding interactions that cause their miscibility at the molecular level. PMID:11948439

  1. 27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy of glasses in the system K2O-Al2O3-SiO2.

    PubMed

    Mundus, C; Müller-Warmuth, W

    1995-10-01

    27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy at 78 MHz has been applied to determine (true) chemical shift and quadrupole coupling parameters of glasses in the system K2O-Al2O3-SiO2 with 60-80 mol% SiO2 and K2O concentrations between 0 and 24 mol%. The powdered crystalline aluminosilicates andalusite and sillimanite have also been examined. In the glasses, all Al appears to be tetrahedrally bound in the aluminosilicate network unless x = mol% K2O:mol% Al2O3 becomes extremely small. Upon decreasing x the distortion of the tetrahedral Al(OSi)4 units increases in steps, and possible explanations are discussed. Six-coordinated aluminum observed for x < 0.2 is connected with the occurrence of interstitial Al3+ ions which charge-compensate the AlO4 units in addition to K+. PMID:8748646

  2. Noninvasive detection of graft rejection by in vivo (19) F MRI in the early stage.

    PubMed

    Flögel, U; Su, S; Kreideweiss, I; Ding, Z; Galbarz, L; Fu, J; Jacoby, C; Witzke, O; Schrader, J

    2011-02-01

    Diagnosis of transplant rejection requires tissue biopsy and entails risks. Here, we describe a new (19) F MRI approach for noninvasive visualization of organ rejection via the macrophage host response. For this, we employed biochemically inert emulsified perfluorocarbons (PFCs), known to be preferentially phagocytized by monocytes and macrophages. Isografts from C57BL/6 or allografts from C57B10.A mice were heterotopically transplanted into C57BL/6 recipients. PFCs were applied intravenously followed by (1) H/(19) F MRI at 9.4 T 24 h after injection. (1) H images showed a similar position and anatomy of the graft in the abdomen for both cases. However, corresponding (19) F signals were only observed in allogenic tissue. (1) H/(19) F MRI enabled us to detect the initial immune response not later than 3 days after surgery, when conventional parameters did not reveal any signs of rejection. In allografts, the observed (19) F signal strongly increased with time and correlated with the extent of rejection. In separate experiments, rapamycin was used to demonstrate the ability of (19) F MRI to monitor immunosuppressive therapy. Thus, PFCs can serve as positive contrast agent for the early detection of transplant rejection by (19) F MRI with high spatial resolution and an excellent degree of specificity due to lack of any (19) F background. PMID:21214858

  3. Gadolinium-modulated 19F signals from Perfluorocarbon Nanoparticles as a New Strategy for Molecular Imaging

    PubMed Central

    Neubauer, Anne M.; Myerson, Jacob; Caruthers, Shelton D.; Hockett, Franklin D.; Winter, Patrick M.; Chen, Junjie; Gaffney, Patrick J.; Robertson, J. David; Lanza, Gregory M.; Wickline, Samuel A.

    2008-01-01

    Recent advances in the design of fluorinated nanoparticles for magnetic resonance molecular imaging have enabled specific detection of 19F nuclei, providing unique and quantifiable spectral signatures. However, a pressing need for signal enhancement exists because the total 19F in imaging voxels is often limited. By directly incorporating a relaxation agent (gadolinium) into the lipid monolayer that surrounds the perfluorocarbon, a marked augmentation of the 19F signal from 200nm nanoparticles was achieved. This design increases the magnetic relaxation rate of the 19F nuclei 4-fold at 1.5 T and effects a 125% increase in signal, an effect which is maintained when they are targeted to human plasma clots. By varying the surface concentration of gadolinium, the relaxation effect can be quantitatively modulated to tailor particle properties. This novel strategy dramatically improves the sensitivity and range of 19F MRI/MRS and forms the basis for designing contrast agents capable of sensing their surface chemistry. PMID:18956457

  4. Visualizing arthritic inflammation and therapeutic response by fluorine-19 magnetic resonance imaging (19F MRI)

    PubMed Central

    2012-01-01

    Background Non-invasive imaging of inflammation to measure the progression of autoimmune diseases, such as rheumatoid arthritis (RA), and to monitor responses to therapy is critically needed. V-Sense, a perfluorocarbon (PFC) contrast agent that preferentially labels inflammatory cells, which are then recruited out of systemic circulation to sites of inflammation, enables detection by 19F MRI. With no 19F background in the host, detection is highly-specific and can act as a proxy biomarker of the degree of inflammation present. Methods Collagen-induced arthritis in rats, a model with many similarities to human RA, was used to study the ability of the PFC contrast agent to reveal the accumulation of inflammation over time using 19F MRI. Disease progression in the rat hind limbs was monitored by caliper measurements and 19F MRI on days 15, 22 and 29, including the height of clinically symptomatic disease. Naïve rats served as controls. The capacity of the PFC contrast agent and 19F MRI to assess the effectiveness of therapy was studied in a cohort of rats administered oral prednisolone on days 14 to 28. Results Quantification of 19F signal measured by MRI in affected limbs was linearly correlated with disease severity. In animals with progressive disease, increases in 19F signal reflected the ongoing recruitment of inflammatory cells to the site, while no increase in 19F signal was observed in animals receiving treatment which resulted in clinical resolution of disease. Conclusion These results indicate that 19F MRI may be used to quantitatively and qualitatively evaluate longitudinal responses to a therapeutic regimen, while additionally revealing the recruitment of monocytic cells involved in the inflammatory process to the anatomical site. This study may support the use of 19F MRI to clinically quantify and monitor the severity of inflammation, and to assess the effectiveness of treatments in RA and other diseases with an inflammatory component. PMID:22721447

  5. MAGIC highlights

    NASA Astrophysics Data System (ADS)

    López-Coto, Rubén

    2016-07-01

    The present generation of Imaging Air Cherenkov Telescopes (IACTs) has greatly improved our knowledge on the Very High Energy (VHE) side of our Universe. The MAGIC IACTs operate since 2004 with one telescope and since 2009 as a two telescope stereoscopic system. I will outline a few of our latest and most relevant results: the discovery of pulsed emission from the Crab pulsar at VHE, recently found to extend up to 400 GeV and along the "bridge" of the light curve, the measurement of the Crab nebula spectrum over three decades of energy, the discovery of VHE γ-ray emission from the PWN 3C 58, the very rapid emission of IC 310, in addition to dark matter studies. The results that will be described here and the planned deep observations in the next years will pave the path for the future generation of IACTs.

  6. The Versatile Magic Square.

    ERIC Educational Resources Information Center

    Watson, Gale A.

    2003-01-01

    Demonstrates the transformations that are possible to construct a variety of magic squares, including modifications to challenge students from elementary grades through algebra. Presents an example of using magic squares with students who have special needs. (YDS)

  7. Perception, Illusion, and Magic.

    ERIC Educational Resources Information Center

    Solomon, Paul R.

    1980-01-01

    Describes a psychology course in which magical illusions were used for teaching the principles of sensation and perception. Students read psychological, philosophical, historical, and magical literature on illusion, performed a magical illusion, and analyzed the illusion in terms of the psychological principles involved. (Author/KC)

  8. Shortening spin-lattice relaxation using a copper-chelated lipid at low-temperatures - A magic angle spinning solid-state NMR study on a membrane-bound protein.

    PubMed

    Yamamoto, Kazutoshi; Caporini, Marc A; Im, Sangchoul; Waskell, Lucy; Ramamoorthy, Ayyalusamy

    2013-12-01

    Inherent low sensitivity of NMR spectroscopy has been a major disadvantage, especially to study biomolecules like membrane proteins. Recent studies have successfully demonstrated the advantages of performing solid-state NMR experiments at very low and ultralow temperatures to enhance the sensitivity. However, the long spin-lattice relaxation time, T1, at very low temperatures is a major limitation. To overcome this difficulty, we demonstrate the use of a copper-chelated lipid for magic angle spinning solid-state NMR measurements on cytochrome-b5 reconstituted in multilamellar vesicles. Our results on multilamellar vesicles containing as small as 0.5mol% of a copper-chelated lipid can significantly shorten T1 of protons, which can be used to considerably reduce the data collection time or to enhance the signal-to-noise ratio. We also monitored the effect of slow cooling on the resolution and sensitivity of (13)C and (15)N signals from the protein and (13)C signals from lipids. PMID:24246881

  9. In vivo high-resolution magic angle spinning magnetic resonance spectroscopy of Drosophila melanogaster at 14.1 T shows trauma in aging and in innate immune-deficiency is linked to reduced insulin signaling

    PubMed Central

    RIGHI, VALERIA; APIDIANAKIS, YIORGOS; MINTZOPOULOS, DIONYSSIOS; ASTRAKAS, LOUKAS; RAHME, LAURENCE G.; TZIKA, A. ARIA

    2010-01-01

    In vivo magnetic resonance spectroscopy (MRS), a non-destructive biochemical tool for investigating live organisms, has yet to be used in the fruit fly Drosophila melanogaster, a useful model organism for investigating genetics and physiology. We developed and implemented a high-resolution magic-angle-spinning (HRMAS) MRS method to investigate live Drosophila at 14.1 T. We demonstrated, for the first time, the feasibility of using HRMAS MRS for molecular characterization of Drosophila with a conventional MR spectrometer equipped with an HRMAS probe. We showed that the metabolic HRMAS MRS profiles of injured, aged wild-type (wt) flies and of immune deficient (imd) flies were more similar to chico flies mutated at the chico gene in the insulin signaling pathway, which is analogous to insulin receptor substrate 1–4 (IRS1–4) in mammals and less to those of adipokinetic hormone receptor (akhr) mutant flies, which have an obese phenotype. We thus provide evidence for the hypothesis that trauma in aging and in innate immune-deficiency is linked to insulin signaling. This link may explain the mitochondrial dysfunction that accompanies insulin resistance and muscle wasting that occurs in trauma, aging and immune system deficiencies, leading to higher susceptibility to infection. Our approach advances the development of novel in vivo non-destructive research approaches in Drosophila, suggests biomarkers for investigation of biomedical paradigms, and thus may contribute to novel therapeutic development. PMID:20596596

  10. Stochastic molecular motions in the nematic, smectic-A, and solid phases of p,p{sup '}-di-n-heptyl-azoxybenzene as seen by quasielastic neutron scattering and {sup 13}C cross-polarization magic-angle-spinning NMR

    SciTech Connect

    ZajaPc, Wojciech; Urban, Stanislaw; Domenici, Valentina; Geppi, Marco; Veracini, Carlo Alberto; Telling, Mark T. F.; Gabrys, Barbara J.

    2006-05-15

    Molecular rotational dynamics in p,p{sup '}-di-n-heptyl-azoxybenzene was studied by means of quasielastic neutron scattering (QENS) and {sup 13}C cross-polarization magic-angle-spinning (CPMAS) NMR. Fast reorientation of the hydrogen nuclei was observed by QENS in the two liquid crystalline (LC) phases nematic and smectic A, as well as in the crystalline phase. The latter could not be restricted to the -CH{sub 3} rotations alone, and a clear indication was found of some other reorientation motions persisting in the crystal. Two Lorentz-type components convoluted with the resolution function gave an excellent fit to the QENS spectra in both LC phases. The narrow (slow) component was attributed to the reorientation of the whole molecule around the long axis. The corresponding characteristic time of {approx}130 ps agreed well with the values obtained in recent dielectric relaxation and {sup 2}H NMR studies. The full width at half maximum of the broader (fast) component shows a quadratic Q dependence (Q is the momentum transfer). Hence the corresponding motions could be described by a stretched exponential correlation function and were interpreted as various ''crankshaft-type'' motions within the alkyl tails. The {sup 13}C CPMAS experiments fully corroborated the QENS results, sometimes considered ambiguous in complex systems.

  11. Stochastic molecular motions in the nematic, smectic-A, and solid phases of p,p'-di-n-heptyl-azoxybenzene as seen by quasielastic neutron scattering and 13C cross-polarization magic-angle-spinning NMR.

    PubMed

    Zajac, Wojciech; Urban, Stanisław; Domenici, Valentina; Geppi, Marco; Veracini, Carlo Alberto; Telling, Mark T F; Gabryś, Barbara J

    2006-05-01

    Molecular rotational dynamics in p,p'-di-n-heptyl-azoxybenzene was studied by means of quasielastic neutron scattering (QENS) and 13C cross-polarization magic-angle-spinning (CPMAS) NMR. Fast reorientation of the hydrogen nuclei was observed by QENS in the two liquid crystalline (LC) phases nematic and smectic A, as well as in the crystalline phase. The latter could not be restricted to the -CH3 rotations alone, and a clear indication was found of some other reorientation motions persisting in the crystal. Two Lorentz-type components convoluted with the resolution function gave an excellent fit to the QENS spectra in both LC phases. The narrow (slow) component was attributed to the reorientation of the whole molecule around the long axis. The corresponding characteristic time of approximately 130 ps agreed well with the values obtained in recent dielectric relaxation and 2H NMR studies. The full width at half maximum of the broader (fast) component shows a quadratic Q dependence (Q is the momentum transfer). Hence the corresponding motions could be described by a stretched exponential correlation function and were interpreted as various "crankshaft-type" motions within the alkyl tails. The 13C CPMAS experiments fully corroborated the QENS results, sometimes considered ambiguous in complex systems. PMID:16802951

  12. {sup 13}C, {sup 1}H, {sup 6}Li magic-angle spinning nuclear magnetic resonance, electron paramagnetic resonance, and Fourier transform infrared study of intercalation electrodes based in ultrasoft carbons obtained below 3100 K

    SciTech Connect

    Alcantara, R.; Madrigal, F.J.F.; Lavela, P.; Tirado, J.L.; Mateos, J.M.J.; Stoyanova, R.; Zhecheva, E.

    1999-01-01

    The past decade has seen an important development of materials for high-performance energy storage systems. Particularly, the field of electrode materials for advanced lithium batteries has attracted the interest of numerous researchers. Petroleum coke samples of different origins and heat treated at different temperatures below 3100 K have been studied by spectroscopic and electrochemical procedures. According to {sup 13}C and {sup 1}H magic-angle spinning (MAS) nuclear magnetic resonance (NMR), infrared (IR), and electron paramagnetic resonance (EPR) data, aromatic compounds and surface OH groups are present in green coke samples. The preparation of CMB (combustible) sample from 1673 K leads to a low-temperature graphitization process, as shown by the occurrence of multiphase products containing both turbostatic and graphitized solid. This process is accompanied by the loss of aromatic compounds and surface hydroxyls. The optimization of the lithium intercalation electrodes based in the green coke materials was carried out by thermal treatment at 1023 K under dynamic vacuum conditions. Such pretreatment of the electrode material leads to marked enhancement of reversible capacities without the higher temperatures usually required for other soft carbon materials. Finally, the results of {sup 6}Li MAS NMR and EPR have been correlated with the experimental determination of lithium diffusion coefficients and surface properties. On the basis of these results, spin resonance spectroscopies are found to be a powerful tool to discern between the different petroleum coke samples to select the active electrode material with best performance.

  13. Shortening Spin-lattice Relaxation Using a Copper-Chelated lipid at Low-Temperatures – A Magic Angle Spinning Solid-State NMR Study on a Membrane-Bound Protein

    PubMed Central

    Yamamoto, Kazutoshi; Caporini, Marc; Im, Sangchoul; Waskell, Lucy; Ramamoorthy, Ayyalusamy

    2013-01-01

    Inherent low sensitivity of NMR spectroscopy has been a major disadvantage, especially to study biomolecules like membrane proteins. Recent studies have successfully demonstrated the advantages of performing solid-state NMR experiments at very low and ultralow temperatures to enhance the sensitivity. However, the long spin-lattice relaxation time, T1, at very low temperatures is a major limitation. To overcome this difficulty, we demonstrate the use of a copper-chelated lipid for magic angle spinning solid-state NMR measurements on cytochrome-b5 reconstituted in multilamellar vesicles. Our results on multilamellar vesicles containing as small as 0.5 mole % of a copper-chelated lipid can significantly shorten T1 of protons, which can be used to considerably reduce the data collection time or to enhance the signal-to-noise ratio. We also monitored the effect of slow cooling on the resolution and sensitivity of 13C and 15N signals from the protein and 13C signals from lipids. PMID:24246881

  14. Achievement of 1 H-19 F heteronuclear experiments using the conventional spectrometer with a shared single high band amplifier.

    PubMed

    Sakuma, Chiseko; Kurita, Jun-ichi; Furihata, Kazuo; Tashiro, Mitsuru

    2015-05-01

    The (1)H-(19) F heteronuclear NMR experiments were achieved using the conventional spectrometer equipped with a single high band amplifier and a (1)H/(19)F/(13) C double-tuned probe. Although double high band amplifiers are generally required to perform such experiments, a simple modification of pathway in the conventional spectrometer was capable of acquiring various (1)H-(19)F heteronuclear spectra. The efficiency of the present technique was demonstrated in an application for (19)F{(1)H} and (1)H{(19)F} saturation transfer difference experiments. PMID:25808615

  15. A symmetrical fluorous dendron-cyanine dye-conjugated bimodal nanoprobe for quantitative 19F MRI and NIR fluorescence bioimaging.

    PubMed

    Wang, Zhe; Yue, Xuyi; Wang, Yu; Qian, Chunqi; Huang, Peng; Lizak, Marty; Niu, Gang; Wang, Fu; Rong, Pengfei; Kiesewetter, Dale O; Ma, Ying; Chen, Xiaoyuan

    2014-08-01

    (19)F MRI and optical imaging are two powerful noninvasive molecular imaging modalities in biomedical applications. (19)F MRI has great potential for high resolution in vivo imaging, while fluorescent probes enable ultracontrast cellular/tissue imaging with high accuracy and sensitivity. A bimodal nanoprobe is developed, integrating the merits of (19)F MRI and fluorescence imaging into a single synthetic molecule, which is further engineered into nanoprobe, by addressing shortcomings of conventional contrast agents to explore the quantitative (19)F MRI and fluorescence imaging and cell tracking. Results show that this bimodal imaging nanoprobe presents high correlation of (19)F MR signal and NIR fluorescence intensity in vitro and in vivo. Additionally, this nanoprobe enables quantitative (19)F MR analysis, confirmed by a complementary fluorescence analysis. This unique feature can hardly be obtained by traditional (19)F MRI contrast agents. It is envisioned that this nanoprobe can hold great potential for quantitative and sensitive multi-modal molecular imaging. PMID:24789108

  16. Measurement of Long Range 1H-19F Scalar Coupling Constants and their Glycosidic Torsion Dependence in 5-Fluoropyrimidine Substituted RNA

    PubMed Central

    Hennig, Mirko; Munzarová, Markéta L.; Bermel, Wolfgang; Scott, Lincoln G.; Sklenár̂, Vladimír; Williamson, James R.

    2008-01-01

    Long range scalar 5J(H1’,F) couplings were observed in 5-fluoropyrimidine substituted RNA. We developed a novel S3E-19F-α,β-edited NOESY experiment for quantitation of these long range scalar 5J(H1’,F), where the J-couplings can be extracted from inspection of intraresidual (H1’,H6) NOE crosspeaks. Quantum chemical calculations were exploited to investigate the relation between scalar couplings and conformations around the glycosidic bond in oligonucleotides. The theoretical dependence of the observed 5J(H1’,F) couplings on the torsion angle χ can be described by a generalized Karplus relationship. The corresponding density functional theory (DFT) analysis is outlined. Additional NMR experiments facilitating the resonance assignments of 5-fluoropyrimidine substituted RNAs are described and chemical shift changes due to altered shielding in the presence of fluorine-19 (19F) are presented. PMID:16637654

  17. Simultaneous detection of distinct ubiquitin chain topologies by 19F NMR.

    PubMed

    Shekhawat, Sujan S; Pham, Grace H; Prabakaran, Jyothiprashanth; Strieter, Eric R

    2014-10-17

    The dynamic interplay between ubiquitin (Ub) chain construction and destruction is critical for the regulation of many cellular pathways. To understand these processes, it would be ideal to simultaneously detect different Ub chains as they are created and destroyed in the cell. This objective cannot be achieved with existing detection strategies. Here, we report on the use of 19F Nuclear Magnetic Resonance (NMR) spectroscopy to detect and characterize conformationally distinct Ub oligomers. By exploiting the environmental sensitivity of the 19F nucleus and the conformational diversity found among Ub chains of different linkage types, we can simultaneously resolve the 19F NMR signals for mono-Ub and three distinct di-Ub oligomers (K6, K48, and K63) in heterogeneous mixtures. The utility of this approach is demonstrated by the ability to interrogate the selectivity of deubiquitinases with multiple Ub substrates in real time. We also demonstrate that 19F NMR can be used to discern Ub linkages that are formed by select E3 ligases found in pathogenic bacteria. Collectively, our results assert the potential of 19F NMR for monitoring Ub signaling in cells to reveal fundamental insights about the associated cellular pathways. PMID:25119846

  18. Simultaneous Detection of Distinct Ubiquitin Chain Topologies by 19F NMR

    PubMed Central

    2015-01-01

    The dynamic interplay between ubiquitin (Ub) chain construction and destruction is critical for the regulation of many cellular pathways. To understand these processes, it would be ideal to simultaneously detect different Ub chains as they are created and destroyed in the cell. This objective cannot be achieved with existing detection strategies. Here, we report on the use of 19F Nuclear Magnetic Resonance (NMR) spectroscopy to detect and characterize conformationally distinct Ub oligomers. By exploiting the environmental sensitivity of the 19F nucleus and the conformational diversity found among Ub chains of different linkage types, we can simultaneously resolve the 19F NMR signals for mono-Ub and three distinct di-Ub oligomers (K6, K48, and K63) in heterogeneous mixtures. The utility of this approach is demonstrated by the ability to interrogate the selectivity of deubiquitinases with multiple Ub substrates in real time. We also demonstrate that 19F NMR can be used to discern Ub linkages that are formed by select E3 ligases found in pathogenic bacteria. Collectively, our results assert the potential of 19F NMR for monitoring Ub signaling in cells to reveal fundamental insights about the associated cellular pathways. PMID:25119846

  19. Contribution of 19F resonances on 18O( p, α)15N reaction rate

    NASA Astrophysics Data System (ADS)

    Benmeslem, Meriem; Chafa, Azzedine; Barhoumi, Slimane; Tribeche, Mouloud

    2014-08-01

    The 18O( p, α)15N reaction influences the isotopes production such as 19F, 18O, and 15N which can be used to test the models of stellar evolution. 19F is synthesized in both asymptotic giant branch (AGB) and metal-rich Wolf-Rayet (WR) stars. Using R-matrix theory we allow new values of resonances parameters in 19F. We show that the most important contribution to the differential and total cross section at low energies, comes from the levels in 19F situated at resonances energies E R =151, 680 and 840 keV with spin and parity 1/2+. The total width of the 680 keV resonance is badly known. So, we have focused on this broad resonance corresponding to the 8.65 MeV level in 19F. We delimit the temperature range in which each resonance contribution to the total reaction rate occurs by analyzing the ratio ( N A < σν> i / N A < σν>). This allowed us to show that the 680 and 840 keV broad resonances strongly dominate the reaction rate over the stellar temperature range T 9=0.02-0.06 and T 9=0.5-5. Finally, these results were compared to NACRE and Iliadis astrophysical compilations.

  20. Prediction of (19)F NMR Chemical Shifts in Labeled Proteins: Computational Protocol and Case Study.

    PubMed

    Isley, William C; Urick, Andrew K; Pomerantz, William C K; Cramer, Christopher J

    2016-07-01

    The structural analysis of ligand complexation in biomolecular systems is important in the design of new medicinal therapeutic agents; however, monitoring subtle structural changes in a protein's microenvironment is a challenging and complex problem. In this regard, the use of protein-based (19)F NMR for screening low-molecular-weight molecules (i.e., fragments) can be an especially powerful tool to aid in drug design. Resonance assignment of the protein's (19)F NMR spectrum is necessary for structural analysis. Here, a quantum chemical method has been developed as an initial approach to facilitate the assignment of a fluorinated protein's (19)F NMR spectrum. The epigenetic "reader" domain of protein Brd4 was taken as a case study to assess the strengths and limitations of the method. The overall modeling protocol predicts chemical shifts for residues in rigid proteins with good accuracy; proper accounting for explicit solvation of fluorinated residues by water is critical. PMID:27218275

  1. In Vivo Imaging of Stepwise Vessel Occlusion in Cerebral Photothrombosis of Mice by 19F MRI

    PubMed Central

    Kleinschnitz, Christoph; Kampf, Thomas; Jakob, Peter M.; Stoll, Guido

    2011-01-01

    Background 19F magnetic resonance imaging (MRI) was recently introduced as a promising technique for in vivo cell tracking. In the present study we compared 19F MRI with iron-enhanced MRI in mice with photothrombosis (PT) at 7 Tesla. PT represents a model of focal cerebral ischemia exhibiting acute vessel occlusion and delayed neuroinflammation. Methods/Principal Findings Perfluorocarbons (PFC) or superparamagnetic iron oxide particles (SPIO) were injected intravenously at different time points after photothrombotic infarction. While administration of PFC directly after PT induction led to a strong 19F signal throughout the entire lesion, two hours delayed application resulted in a rim-like 19F signal at the outer edge of the lesion. These findings closely resembled the distribution of signal loss on T2-weighted MRI seen after SPIO injection reflecting intravascular accumulation of iron particles trapped in vessel thrombi as confirmed histologically. By sequential administration of two chemically shifted PFC compounds 0 and 2 hours after illumination the different spatial distribution of the 19F markers (infarct core/rim) could be visualized in the same animal. When PFC were applied at day 6 the fluorine marker was only detected after long acquisition times ex vivo. SPIO-enhanced MRI showed slight signal loss in vivo which was much more prominent ex vivo indicative for neuroinflammation at this late lesion stage. Conclusion Our study shows that vessel occlusion can be followed in vivo by 19F and SPIO-enhanced high-field MRI while in vivo imaging of neuroinflammation remains challenging. The timing of contrast agent application was the major determinant of the underlying processes depicted by both imaging techniques. Importantly, sequential application of different PFC compounds allowed depiction of ongoing vessel occlusion from the core to the margin of the ischemic lesions in a single MRI measurement. PMID:22194810

  2. 19F-NMR Study on the Equilateral Triangular Spin Tube CsCrF4

    NASA Astrophysics Data System (ADS)

    Matsui, Kazuki; Goto, Takayuki; Manaka, Hirotaka; Miura, Yoko

    In order to investigate the hyperfine coupling of three inequivalent 19F sites in the equilateral triangular spin-tube antiferromagnet CsCrF4, we have measured the temperature dependence of 19F-NMR Knight shift in the paramagnetic state above 20K. The hyperfine coupling constants for three F-sites were determined to be -0.170, 0.280 and -0.045 T/μB, and were found to be consistent with the observed spectra at 1.65K, where the system is possibly in the ordered state.

  3. Probing the Pu4 + magnetic moment in PuF4 with 19F NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Capan, Cigdem; Dempsey, Richard J.; Sinkov, Sergey; McNamara, Bruce K.; Cho, Herman

    2016-06-01

    The magnetic fields produced by Pu4 + centers have been measured by 19F NMR spectroscopy to elucidate the Pu-F electronic interactions in polycrystalline PuF4. Spectra acquired at applied fields of 2.35 and 7.05 T reveal a linear scaling of the 19F line shape. A model is presented that treats the line broadening and shifts as due to dipolar fields produced by Pu valence electrons in localized noninteracting orbitals. Alternative explanations for the observed line shape involving covalent Pu-F bonding, superexchange interactions, and electronic configurations with enhanced magnetic moments are considered.

  4. Applications of (19)F-NMR in Fragment-Based Drug Discovery.

    PubMed

    Norton, Raymond S; Leung, Eleanor W W; Chandrashekaran, Indu R; MacRaild, Christopher A

    2016-01-01

    (19)F-NMR has proved to be a valuable tool in fragment-based drug discovery. Its applications include screening libraries of fluorinated fragments, assessing competition among elaborated fragments and identifying the binding poses of promising hits. By observing fluorine in both the ligand and the target protein, useful information can be obtained on not only the binding pose but also the dynamics of ligand-protein interactions. These applications of (19)F-NMR will be illustrated in this review with studies from our fragment-based drug discovery campaigns against protein targets in parasitic and infectious diseases. PMID:27438818

  5. The Magic of Balanced Groups: Educational Applications of Magic Squares

    ERIC Educational Resources Information Center

    Bosse, Michael J.; Nandakumar, N. R.; Ore, Melanie L.

    2007-01-01

    This paper provides students with many interesting observations regarding the nature of magic squares, magic rectangles, and quasi-magic squares and provides tools for teachers to group students into ability-balanced cooperative learning groups.

  6. A 23Na magic angle spinning nuclear magnetic resonance, XANES, and high-temperature X-ray diffraction study of NaUO3, Na4UO5, and Na2U2O7.

    PubMed

    Smith, A L; Raison, P E; Martel, L; Charpentier, T; Farnan, I; Prieur, D; Hennig, C; Scheinost, A C; Konings, R J M; Cheetham, A K

    2014-01-01

    The valence state of uranium has been confirmed for the three sodium uranates NaU(V)O3/[Rn](5f(1)), Na4U(VI)O5/[Rn](5f(0)), and Na2U(VI)2O7/[Rn](5f(0)), using X-ray absorption near-edge structure (XANES) spectroscopy. Solid-state (23)Na magic angle spinning nuclear magnetic resonance (MAS NMR) measurements have been performed for the first time, yielding chemical shifts at -29.1 (NaUO3), 15.1 (Na4UO5), and -14.1 and -19 ppm (Na1 8-fold coordinated and Na2 7-fold coordinated in Na2U2O7), respectively. The [Rn]5f(1) electronic structure of uranium in NaUO3 causes a paramagnetic shift in comparison to Na4UO5 and Na2U2O7, where the electronic structure is [Rn]5f(0). A (23)Na multi quantum magic angle spinning (MQMAS) study on Na2U2O7 has confirmed a monoclinic rather than rhombohedral structure with evidence for two distinct Na sites. DFT calculations of the NMR parameters on the nonmagnetic compounds Na4UO5 and Na2U2O7 have permitted the differentiation between the two Na sites of the Na2U2O7 structure. The linear thermal expansion coefficients of all three compounds have been determined using high-temperature X-ray diffraction: αa = 22.7 × 10(-6) K(-1), αb = 12.9 × 10(-6) K(-1), αc = 16.2 × 10(-6) K(-1), and αvol = 52.8 × 10(-6) K(-1) for NaUO3 in the range 298-1273 K; αa = 37.1 × 10(-6) K(-1), αc = 6.2 × 10(-6) K(-1), and αvol = 81.8 × 10(-6) K(-1) for Na4UO5 in the range 298-1073 K; αa = 6.7 × 10(-6) K(-1), αb = 14.4 × 10(-6) K(-1), αc = 26.8 × 10(-6) K(-1), αβ = -7.8 × 10(-6) K(-1), and αvol = -217.6 × 10(-6) K(-1) for Na2U2O7 in the range 298-573 K. The α to β phase transition reported for the last compound above about 600 K was not observed in the present studies, either by high-temperature X-ray diffraction or by differential scanning calorimetry. PMID:24350659

  7. 31P magic angle spinning NMR study of flux-grown rare-earth element orthophosphate (monazite/xenotime) solid solutions: evidence of random cation distribution from paramagnetically shifted NMR resonances.

    PubMed

    Palke, Aaron C; Stebbins, Jonathan F; Boatner, Lynn A

    2013-11-01

    We present (31)P magic angle spinning nuclear magnetic resonance spectra of flux-grown solid solutions of La(1-x)Ce(x)PO4 (x between 0.027 and 0.32) having the monoclinic monazite structure, and of Y(1-x)M(x)PO4 (M = V(n+), Ce(3+), Nd(3+), x between 0.001 and 0.014) having the tetragonal zircon structure. Paramagnetically shifted NMR resonances are observed in all samples due to the presence of paramagnetic V(n+), Ce(3+), and Nd(3+) in the diamagnetic LaPO4 or YPO4. As a first-order observation, the number and relative intensities of these peaks are related to the symmetry and structure of the diamagnetic host phase. The presence of paramagnetic shifts allows for increased resolution between NMR resonances for distinct atomic species which leads to the observation of low intensity peaks related to PO4 species having more than one paramagnetic neighbor two or four atomic bonds away. Through careful analysis of peak areas and comparison with predictions for simple models, it was determined that solid solutions in the systems examined here are characterized by complete disorder (random distribution) of diamagnetic La(3+) or Y(3+) with the paramagnetic substitutional species Ce(3+) and Nd(3+). The increased resolution given by the paramagnetic interactions also leads to the observation of splitting of specific resonances in the (31)P NMR spectra that may be caused by local, small-scale distortions from the substitution of ions having dissimilar ionic radii. PMID:24131129

  8. The Role of High-Resolution Magic Angle Spinning 1H Nuclear Magnetic Resonance Spectroscopy for Predicting the Invasive Component in Patients with Ductal Carcinoma In Situ Diagnosed on Preoperative Biopsy.

    PubMed

    Chae, Eun Young; Shin, Hee Jung; Kim, Suhkmann; Baek, Hyeon-Man; Yoon, Dahye; Kim, Siwon; Shim, Ye Eun; Kim, Hak Hee; Cha, Joo Hee; Choi, Woo Jung; Lee, Jeong Hyun; Shin, Ji Hoon; Lee, Hee Jin; Gong, Gyungyub

    2016-01-01

    The purpose of this study was to evaluate the role of high-resolution magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy in patients with ductal carcinoma in situ (DCIS) diagnosed on preoperative biopsy. We investigated whether the metabolic profiling of tissue samples using HR-MAS 1H NMR spectroscopy could be used to distinguish between DCIS lesions with or without an invasive component. Our institutional review board approved this combined retrospective and prospective study. Tissue samples were collected from 30 patients with pure DCIS and from 30 with DCIS accompanying invasive carcinoma. All patients were diagnosed with DCIS by preoperative core-needle biopsy and underwent surgical resection. The metabolic profiling of tissue samples was performed by HR-MAS 1H NMR spectroscopy. All observable metabolite signals were identified and quantified in all tissue samples. Metabolite intensity normalized by total spectral intensities was compared according to the tumor type using the Mann-Whitney test. Multivariate analysis was performed with orthogonal projections to latent structure-discriminant analysis (OPLS-DA). By univariate analysis, the metabolite concentrations of choline-containing compounds obtained with HR-MAS 1H NMR spectroscopy did not differ significantly between the pure DCIS and DCIS accompanying invasive carcinoma groups. However, the GPC/PC ratio was higher in the pure DCIS group than in the DCIS accompanying invasive carcinoma group (p = 0.004, Bonferroni-corrected p = 0.064), as well as the concentration of myo-inositol and succinate. By multivariate analysis, the OPLS-DA models built with HR-MAS MR metabolic profiles could clearly discriminate between pure DCIS and DCIS accompanying invasive carcinoma. Our preliminary results suggest that HR-MAS MR metabolomics on breast tissue may be able to distinguish between DCIS lesions with or without an invasive component. PMID:27560937

  9. Nano-Mole Scale Side-Chain Signal Assignment by 1H-Detected Protein Solid-State NMR by Ultra-Fast Magic-Angle Spinning and Stereo-Array Isotope Labeling

    PubMed Central

    Nishiyama, Yusuke; Endo, Yuki; Nemoto, Takahiro; Yamauchi, Kazuo; Asakura, Tetsuo; Takeda, Mitsuhiro; Terauchi, Tsutomu; Kainosho, Masatsune; Ishii, Yoshitaka

    2015-01-01

    We present a general approach in 1H-detected 13C solid-state NMR (SSNMR) for side-chain signal assignments of 10-50 nmol quantities of proteins using a combination of a high magnetic field, ultra-fast magic-angle spinning (MAS) at ~80 kHz, and stereo-array-isotope-labeled (SAIL) proteins [Kainosho M. et al., Nature 440, 52–57, 2006]. First, we demonstrate that 1H indirect detection improves the sensitivity and resolution of 13C SSNMR of SAIL proteins for side-chain assignments in the ultra-fast MAS condition. 1H-detected SSNMR was performed for micro-crystalline ubiquitin (~55 nmol or ~0.5mg) that was SAIL-labeled at seven isoleucine (Ile) residues. Sensitivity was dramatically improved by 1H-detected 2D 1H/13C SSNMR by factors of 5.4-9.7 and 2.1-5.0, respectively, over 13C-detected 2D 1H/13C SSNMR and 1D 13C CPMAS, demonstrating that 2D 1H-detected SSNMR offers not only additional resolution but also sensitivity advantage over 1D 13C detection for the first time. High 1H resolution for the SAIL-labeled side-chain residues offered reasonable resolution even in the 2D data. A 1H-detected 3D 13C/13C/1H experiment on SAIL-ubiquitin provided nearly complete 1H and 13C assignments for seven Ile residues only within ~2.5 h. The results demonstrate the feasibility of side-chain signal assignment in this approach for as little as 10 nmol of a protein sample within ~3 days. The approach is likely applicable to a variety of proteins of biological interest without any requirements of highly efficient protein expression systems. PMID:25856081

  10. Nano-mole scale side-chain signal assignment by 1H-detected protein solid-state NMR by ultra-fast magic-angle spinning and stereo-array isotope labeling.

    PubMed

    Wang, Songlin; Parthasarathy, Sudhakar; Nishiyama, Yusuke; Endo, Yuki; Nemoto, Takahiro; Yamauchi, Kazuo; Asakura, Tetsuo; Takeda, Mitsuhiro; Terauchi, Tsutomu; Kainosho, Masatsune; Ishii, Yoshitaka

    2015-01-01

    We present a general approach in 1H-detected 13C solid-state NMR (SSNMR) for side-chain signal assignments of 10-50 nmol quantities of proteins using a combination of a high magnetic field, ultra-fast magic-angle spinning (MAS) at ~80 kHz, and stereo-array-isotope-labeled (SAIL) proteins [Kainosho M. et al., Nature 440, 52-57, 2006]. First, we demonstrate that 1H indirect detection improves the sensitivity and resolution of 13C SSNMR of SAIL proteins for side-chain assignments in the ultra-fast MAS condition. 1H-detected SSNMR was performed for micro-crystalline ubiquitin (~55 nmol or ~0.5mg) that was SAIL-labeled at seven isoleucine (Ile) residues. Sensitivity was dramatically improved by 1H-detected 2D 1H/13C SSNMR by factors of 5.4-9.7 and 2.1-5.0, respectively, over 13C-detected 2D 1H/13C SSNMR and 1D 13C CPMAS, demonstrating that 2D 1H-detected SSNMR offers not only additional resolution but also sensitivity advantage over 1D 13C detection for the first time. High 1H resolution for the SAIL-labeled side-chain residues offered reasonable resolution even in the 2D data. A 1H-detected 3D 13C/13C/1H experiment on SAIL-ubiquitin provided nearly complete 1H and 13C assignments for seven Ile residues only within ~2.5 h. The results demonstrate the feasibility of side-chain signal assignment in this approach for as little as 10 nmol of a protein sample within ~3 days. The approach is likely applicable to a variety of proteins of biological interest without any requirements of highly efficient protein expression systems. PMID:25856081

  11. Study of lignification by noninvasive techniques in growing maize internodes. An investigation by Fourier transform infrared cross-polarization-magic angle spinning 13C-nuclear magnetic resonance spectroscopy and immunocytochemical transmission electron microscopy.

    PubMed

    Joseleau, J P; Ruel, K

    1997-07-01

    Noninvasive techniques were used for the study in situ of lignification in the maturing cell walls of the maize (Zea mays L.) stem. Within the longitudinal axis of a developing internode all of the stages of lignification can be found. The synthesis of the three types of lignins, p-hydroxyphenylpropane (H), guaiacyl (G), and syringyl (S), was investigated in situ by cross-polarization-magic angle spinning 13C-solid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, and immunocytochemical electron microscopy. The first lignin appearing in the parenchyma is of the G-type preceeding the incorporation of S nuclei in the later stages. However, in vascular bundles, typical absorption bands of S nuclei are visible in the Fourier transform infrared spectra at the earliest stage of lignification. Immunocytochemical determination of the three types of lignin in transmission electron microscopy was possible thanks to the use of antisera prepared against synthetic H, G, and the mixed GS dehydrogenative polymers (K. Ruel, O. Faix, J.P. Joseleau [1994] J Trace Microprobe Tech 12: 247-265). The specificity of the immunological probes demonstrated that there are differences in the relative temporal synthesis of the H, G, and GS lignins in the different tissues undergoing lignification. Considering the intermonomeric linkages predominating in the antigens used for the preparation of the immunological probes, the relative intensities of the labeling obtained provided, for the first time to our knowledge, information about the macromolecular nature of lignins (condensed versus noncondensed) in relation to their ultrastructural localization and development stage. PMID:9232887

  12. The Role of High-Resolution Magic Angle Spinning 1H Nuclear Magnetic Resonance Spectroscopy for Predicting the Invasive Component in Patients with Ductal Carcinoma In Situ Diagnosed on Preoperative Biopsy

    PubMed Central

    Chae, Eun Young; Kim, Suhkmann; Baek, Hyeon-Man; Yoon, Dahye; Kim, Siwon; Shim, Ye Eun; Kim, Hak Hee; Cha, Joo Hee; Choi, Woo Jung; Lee, Jeong Hyun; Shin, Ji Hoon; Lee, Hee Jin; Gong, Gyungyub

    2016-01-01

    The purpose of this study was to evaluate the role of high-resolution magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy in patients with ductal carcinoma in situ (DCIS) diagnosed on preoperative biopsy. We investigated whether the metabolic profiling of tissue samples using HR-MAS 1H NMR spectroscopy could be used to distinguish between DCIS lesions with or without an invasive component. Our institutional review board approved this combined retrospective and prospective study. Tissue samples were collected from 30 patients with pure DCIS and from 30 with DCIS accompanying invasive carcinoma. All patients were diagnosed with DCIS by preoperative core-needle biopsy and underwent surgical resection. The metabolic profiling of tissue samples was performed by HR-MAS 1H NMR spectroscopy. All observable metabolite signals were identified and quantified in all tissue samples. Metabolite intensity normalized by total spectral intensities was compared according to the tumor type using the Mann-Whitney test. Multivariate analysis was performed with orthogonal projections to latent structure-discriminant analysis (OPLS-DA). By univariate analysis, the metabolite concentrations of choline-containing compounds obtained with HR-MAS 1H NMR spectroscopy did not differ significantly between the pure DCIS and DCIS accompanying invasive carcinoma groups. However, the GPC/PC ratio was higher in the pure DCIS group than in the DCIS accompanying invasive carcinoma group (p = 0.004, Bonferroni-corrected p = 0.064), as well as the concentration of myo-inositol and succinate. By multivariate analysis, the OPLS-DA models built with HR-MAS MR metabolic profiles could clearly discriminate between pure DCIS and DCIS accompanying invasive carcinoma. Our preliminary results suggest that HR-MAS MR metabolomics on breast tissue may be able to distinguish between DCIS lesions with or without an invasive component. PMID:27560937

  13. Theoretical investigation of the 19F(p, p0) differential cross section up to Ep = 2.3 MeV

    NASA Astrophysics Data System (ADS)

    Paneta, V.; Gurbich, A.; Kokkoris, M.

    2016-03-01

    The use of experimental cross-section data on fluorine in analytical EBS studies is quite problematic, because they are indeed inadequate and discrepant (up to ∼30%). The evaluated values on the other hand, being produced by incorporating the available experimental cross sections within a unified theoretical approach, provide the most reliable data to be used and are therefore very important. The present work contributes in this field by reproducing and attempting to extend the corresponding evaluation for 19F(p, p0), which ranges up to 1730 keV, to proton energies up to 2250 keV, using the AZURE code. The performed R-matrix calculations involved the simultaneous analysis of several experimental input datasets, as well as spectroscopic information concerning the formed compound nucleus 20Ne, while valuable feedback information was provided by proton benchmarking spectra on ZnF2 taken at Ep = 1730 and 2250 keV and at several backscattering angles for the fine tuning of the parameters used. The problem of the 19F(p, p‧) and 19F(p, αx) contributions in the obtained thick target yield spectra is also discussed.

  14. Determination of methyl 13C-15N dipolar couplings in peptides and proteins by three-dimensional and four-dimensional magic-angle spinning solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Helmus, Jonathan J.; Nadaud, Philippe S.; Höfer, Nicole; Jaroniec, Christopher P.

    2008-02-01

    We describe three- and four-dimensional semiconstant-time transferred echo double resonance (SCT-TEDOR) magic-angle spinning solid-state nuclear magnetic resonance (NMR) experiments for the simultaneous measurement of multiple long-range N15-Cmethyl13 dipolar couplings in uniformly C13, N15-enriched peptides and proteins with high resolution and sensitivity. The methods take advantage of C13 spin topologies characteristic of the side-chain methyl groups in amino acids alanine, isoleucine, leucine, methionine, threonine, and valine to encode up to three distinct frequencies (N15-Cmethyl13 dipolar coupling, N15 chemical shift, and Cmethyl13 chemical shift) within a single SCT evolution period of initial duration ˜1/JCC1 (where JCC1≈35Hz, is the one-bond Cmethyl13-C13 J-coupling) while concurrently suppressing the modulation of NMR coherences due to C13-C13 and N15-C13 J-couplings and transverse relaxation. The SCT-TEDOR schemes offer several important advantages over previous methods of this type. First, significant (approximately twofold to threefold) gains in experimental sensitivity can be realized for weak N15-Cmethyl13 dipolar couplings (corresponding to structurally interesting, ˜3.5Å or longer, distances) and typical Cmethyl13 transverse relaxation rates. Second, the entire SCT evolution period can be used for Cmethyl13 and/or N15 frequency encoding, leading to increased spectral resolution with minimal additional coherence decay. Third, the experiments are inherently "methyl selective," which results in simplified NMR spectra and obviates the use of frequency-selective pulses or other spectral filtering techniques. Finally, the N15-C13 cross-peak buildup trajectories are purely dipolar in nature (i.e., not influenced by J-couplings or relaxation), which enables the straightforward extraction of N15-Cmethyl13 distances using an analytical model. The SCT-TEDOR experiments are demonstrated on a uniformly C13, N15-labeled peptide, N-acetyl-valine, and a 56

  15. Structure of amantadine-bound M2 transmembrane peptide of influenza A in lipid bilayers from magic-angle-spinning solid-state NMR: the role of Ser31 in amantadine binding.

    PubMed

    Cady, Sarah D; Mishanina, Tatiana V; Hong, Mei

    2009-01-30

    The M2 proton channel of influenza A is the target of the antiviral drugs amantadine and rimantadine, whose effectiveness has been abolished by a single-site mutation of Ser31 to Asn in the transmembrane domain of the protein. Recent high-resolution structures of the M2 transmembrane domain obtained from detergent-solubilized protein in solution and crystal environments gave conflicting drug binding sites. We present magic-angle-spinning solid-state NMR results of Ser31 and a number of other residues in the M2 transmembrane peptide (M2TMP) bound to lipid bilayers. Comparison of the spectra of the membrane-bound apo and complexed M2TMP indicates that Ser31 is the site of the largest chemical shift perturbation by amantadine. The chemical shift constraints lead to a monomer structure with a small kink of the helical axis at Gly34. A tetramer model is then constructed using the helix tilt angle and several interhelical distances previously measured on unoriented bilayer samples. This tetramer model differs from the solution and crystal structures in terms of the openness of the N-terminus of the channel, the constriction at Ser31, and the side-chain conformations of Trp41, a residue important for channel gating. Moreover, the tetramer model suggests that Ser31 may interact with amantadine amine via hydrogen bonding. While the apo and drug-bound M2TMP have similar average structures, the complexed peptide has much narrower linewidths at physiological temperature, indicating drug-induced changes of the protein dynamics in the membrane. Further, at low temperature, several residues show narrower lines in the complexed peptide than the apo peptide, indicating that amantadine binding reduces the conformational heterogeneity of specific residues. The differences of the current solid-state NMR structure of the bilayer-bound M2TMP from the detergent-based M2 structures suggest that the M2 conformation is sensitive to the environment, and care must be taken when interpreting

  16. Cell Labeling for 19F MRI: New and Improved Approach to Perfluorocarbon Nanoemulsion Design

    PubMed Central

    Patel, Sravan K.; Williams, Jonathan; Janjic, Jelena M.

    2013-01-01

    This report describes novel perfluorocarbon (PFC) nanoemulsions designed to improve ex vivo cell labeling for 19F magnetic resonance imaging (MRI). 19F MRI is a powerful non-invasive technique for monitoring cells of the immune system in vivo, where cells are labeled ex vivo with PFC nanoemulsions in cell culture. The quality of 19F MRI is directly affected by the quality of ex vivo PFC cell labeling. When co-cultured with cells for longer periods of time, nanoemulsions tend to settle due to high specific weight of PFC oils (1.5–2.0 g/mL). This in turn can decrease efficacy of excess nanoemulsion removal and reliability of the cell labeling in vitro. To solve this problem, novel PFC nanoemulsions are reported which demonstrate lack of sedimentation and high stability under cell labeling conditions. They are monodisperse, have small droplet size (~130 nm) and low polydispersity (<0.15), show a single peak in the 19F nuclear magnetic resonance spectrum at −71.4 ppm and possess high fluorine content. The droplet size and polydispersity remained unchanged after 160 days of follow up at three temperatures (4, 25 and 37 °C). Further, stressors such as elevated temperature in the presence of cells, and centrifugation, did not affect the nanoemulsion droplet size and polydispersity. Detailed synthetic methodology and in vitro testing for these new PFC nanoemulsions is presented. PMID:25586263

  17. A mutagenesis-free approach to assignment of (19)F NMR resonances in biosynthetically labeled proteins.

    PubMed

    Kitevski-LeBlanc, Julianne L; Al-Abdul-Wahid, M Sameer; Prosser, R Scott

    2009-02-18

    Solution NMR studies of protein structure and dynamics using fluorinated amino acid probes are a valuable addition to the repertoire of existing (13)C, (15)N, and (1)H experiments. Despite the numerous advantages of the (19)F nucleus in NMR, protein studies are complicated by the dependence of resonance assignments on site-directed mutagenesis methods which are laborious and often problematic. Here we report an NMR-based route to the assignment of fluorine resonances in (13)C,(15)N-3-fluoro-l-tyrosine labeled calmodulin. The assignment begins with the correlation of the fluorine nucleus to the delta proton in the novel (13)C,(15)N-enriched probe which is achieved using a CT-HCCF-COSY experiment. Connection to the backbone is made through two additional solution NMR experiments, namely the (H(beta))C(beta)(C(gamma)C(delta))H(delta) and HNCACB. Assignments are completed using either previously published backbone chemical shift data or obtained experimentally provided uniform (13)C,(15)N labeling procedures are employed during protein expression. Additional benefits of the (13)C,(15)N-3-fluoro-l-tyrosine probe include the reduction of spectral overlap through ((13)C(19)F) CT-HSQCs, as well as the ability to monitor side chain dynamics using (19)F T(1), T(2), and the (13)C-(19)F NOE. PMID:19173647

  18. Comparison between optimized GRE and RARE sequences for 19F MRI studies

    NASA Astrophysics Data System (ADS)

    Soffientini, Chiara D.; Mastropietro, Alfonso; Caffini, Matteo; Cocco, Sara; Zucca, Ileana; Scotti, Alessandro; Baselli, Giuseppe; Bruzzone, Maria Grazia

    2014-03-01

    In 19F-MRI studies limiting factors are the presence of a low signal due to the low concentration of 19F-nuclei, necessary for biological applications, and the inherent low sensitivity of MRI. Hence, acquiring images using the pulse sequence with the best signal to noise ratio (SNR) by optimizing the acquisition parameters specifically to a 19F compound is a core issue. In 19F-MRI, multiple-spin-echo (RARE) and gradient-echo (GRE) are the two most frequently used pulse sequence families; therefore we performed an optimization study of GRE pulse sequences based on numerical simulations and experimental acquisitions on fluorinated compounds. We compared GRE performance to an optimized RARE sequence. Images were acquired on a 7T MRI preclinical scanner on phantoms containing different fluorinated compounds. Actual relaxation times (T1, T2, T2*) were evaluated in order to predict SNR dependence on sequence parameters. Experimental comparisons between spoiled GRE and RARE, obtained at a fixed acquisition time and in steady state condition, showed RARE sequence outperforming the spoiled GRE (up to 406% higher). Conversely, the use of the unbalanced-SSFP showed a significant increase in SNR compared to RARE (up to 28% higher). Moreover, this sequence (as GRE in general) was confirmed to be virtually insensitive to T1 and T2 relaxation times, after proper optimization, thus improving marker independence from the biological environment. These results confirm the efficacy of the proposed optimization tool and foster further investigation addressing in-vivo applicability.

  19. 19F MRI detection of acute allograft rejection with in vivo perfluorocarbon labeling of immune cells.

    PubMed

    Hitchens, T Kevin; Ye, Qing; Eytan, Danielle F; Janjic, Jelena M; Ahrens, Eric T; Ho, Chien

    2011-04-01

    Current diagnosis of organ rejection following transplantation relies on tissue biopsy, which is not ideal due to sampling limitations and risks associated with the invasive procedure.We have previously shown that cellular magnetic resonance imaging (MRI) of iron-oxide labeled immune-cell infiltration can provide a noninvasive measure of rejection status by detecting areas of hypointensity on T 2*-weighted images. In this study, we tested the feasibility of using a fluorine-based cellular tracer agent to detect macrophage accumulation in rodent models of acute allograft rejection by fluorine-19 ((19) F) MRI and magnetic resonance spectroscopy. This study used two rat models of acute rejection, including abdominal heterotopic cardiac transplant and orthotopic kidney transplant models. Following in vivo labeling of monocytes and macrophages with a commercially available agent containing perfluoro-15-crown-5-ether, we observed (19) F-signal intensity in the organs experiencing rejection by (19) F MRI, and conventional (1) H MRI was used for anatomical context. Immunofluorescence and histology confirmed macrophage labeling. These results are consistent with our previous studies and show the complementary nature of the two cellular imaging techniques. With no background signal, (19) F MRI/magnetic resonance spectroscopy can provide unambiguous detection of fluorine labeled cells, and may be a useful technique for detecting and quantifying rejection grade in patients. PMID:21305593

  20. Symmetry-guided design and fluorous synthesis of a stable and rapidly excreted imaging tracer for (19)F MRI.

    PubMed

    Jiang, Zhong-Xing; Liu, Xin; Jeong, Eun-Kee; Yu, Yihua Bruce

    2009-01-01

    Getting FIT: A bispherical (19)F imaging tracer, (19)FIT, was designed and synthesized. (19)FIT is advantageous over perfluorocarbon-based (19)F imaging agents, as it is not retained in the organs and does not require complex formulation procedures. Imaging agents such as (19)FIT can lead to (19)F magnetic resonance imaging (MRI) playing an important role in drug therapy, analogous to the role played by (1)H MRI in disease diagnosis. PMID:19475598

  1. The metabolism of 2-trifluormethylaniline and its acetanilide in the rat by 19F NMR monitored enzyme hydrolysis and 1H/19F HPLC-NMR spectroscopy.

    PubMed

    Tugnait, M; Lenz, E M; Hofmann, M; Spraul, M; Wilson, I D; Lindon, J C; Nicholson, J K

    2003-01-01

    The urinary excretion profile and identity of the metabolites of 2-trifluoromethyl aniline (2-TFMA) and 2-trifluoromethyl acetanilide (2-TFMAc), following i.p. administration to the rat at 50 mg kg(-1), were determined using a combination of 19F NMR monitored enzyme hydrolysis, SPEC-MS and 19F/1H HPLC-NMR. A total recovery of approximately 96.4% of the dose was excreted into the urine as seven metabolites. The major routes of metabolism were N-conjugation (glucuronidation), and ring-hydroxylation followed by sulphation (and to a lesser extent glucuronidation). The major metabolites excreted into the urine for both compounds were a labile N-conjugated metabolite (a postulated N-glucuronide) and a sulphated ring-hydroxylated metabolite (a postulated 4-amino-5-trifluoromethylphenyl sulphate) following dosing of 2-TFMA. These accounted for approximately 53.0 and 31.5% of the dose, respectively. This study identifies problems on sample component instability in the preparation and analysis procedures. PMID:12467928

  2. The "Magic" Flask.

    ERIC Educational Resources Information Center

    Battino, Rubin; And Others

    1995-01-01

    Presents demonstrations that use a "magic" flask to teach elementary concepts such as the color changes of various indicators and using the scientific method to predict the sequence of color changes. Catches students' attention by using an unexpected trick or element of magic. (JRH)

  3. Chinese "Magic" Mirrors.

    ERIC Educational Resources Information Center

    Swinson, Derek B.

    1992-01-01

    Chinese "magic" mirrors are made from bronze with the front side a mirror and the reverse side a molded image. When light is reflected from the mirror,the image on the reverse side appears. Discusses reflections of conventional mirrors, possible explanations for the magic mirror phenomenon, and applications of the phenomenon to semiconductor…

  4. The "Magic" String

    ERIC Educational Resources Information Center

    Hoover, Todd F.

    2010-01-01

    The "Magic" String is a discrepant event that includes a canister with what appears to be the end of two strings protruding from opposite sides of it. Due to the way the strings are attached inside the canister, it appears as if the strings can magically switch the way they are connected. When one string end is pulled, the observer's expectation…

  5. Operation Magic Tricks.

    ERIC Educational Resources Information Center

    Edwards, Ronald

    This resource book contains 18 magic number tricks that spark the interest and imagination of students as they are led through a variety of mathematical computations and discoveries. Following each activity, students are asked to write about their discoveries and create their own magic tricks. A matrix of skills for all the activities and lists of…

  6. Investigation of the Curvature Induction and Membrane Localization of the Influenza Virus M2 Protein Using Static and Off-Magic-Angle Spinning Solid-State NMR of Oriented Bicelles

    PubMed Central

    Wang, Tuo; Hong, Mei

    2015-01-01

    A wide variety of membrane proteins induce membrane curvature for function, thus it is important to develop new methods to simultaneously determine membrane curvature and protein binding sites in membranes with multiple curvatures. We introduce solid-state NMR methods based on magnetically oriented bicelles and off-magic-angle spinning (OMAS) to measure membrane curvature and the binding site of proteins in mixed-curvature membranes. We demonstrate these methods on the influenza virus M2 protein, which not only acts as a proton channel but also mediates virus assembly and membrane scission. An M2 peptide encompassing the transmembrane (TM) domain and an amphipathic helix, M2(21-61), was studied and compared with the TM peptide (M2TM). Static 31P NMR spectra of magnetically oriented DMPC/DHPC bicelles exhibit a temperature-independent isotropic chemical shift in the presence of M2(21-61) but not M2TM, indicating that the amphipathic helix confers the peptide with the ability to generate a high-curvature phase. 2D 31P spectra indicate that this high-curvature phase is associated with the DHPC bicelle edges, suggestive of the structure of budding viruses from the host cell. 31P- and 13C-detected 1H relaxation times of the lipids indicate that the majority of M2(21-61) is bound to the high-curvature phase. Using OMAS experiments, we resolved the 31P signals of lipids with identical headgroups based on their distinct chemical shift anisotropies. Based on this resolution, 2D 1H-31P correlation spectra show that the amide protons in M2(21-61) correlate with the DMPC but not the DHPC 31P signal of the bicelle, indicating that a small percentage of M2(21-61) partitions into the planar region of the bicelles. These results show that the M2 amphipathic helix induces high membrane curvature and localizes the protein to this phase, in excellent agreement with the membrane-scission function of the protein. These bicelle-based relaxation and OMAS solid-state NMR techniques are

  7. Metabolomics of Breast Cancer Using High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopy: Correlations with 18F-FDG Positron Emission Tomography-Computed Tomography, Dynamic Contrast-Enhanced and Diffusion-Weighted Imaging MRI

    PubMed Central

    Yoon, Haesung; Yoon, Dahye; Yun, Mijin; Choi, Ji Soo; Park, Vivian Youngjean; Kim, Eun-Kyung; Jeong, Joon; Koo, Ja Seung; Yoon, Jung Hyun; Moon, Hee Jung; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Purpose Our goal in this study was to find correlations between breast cancer metabolites and conventional quantitative imaging parameters using high-resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) and to find breast cancer subgroups that show high correlations between metabolites and imaging parameters. Materials and methods Between August 2010 and December 2013, we included 53 female patients (mean age 49.6 years; age range 32–75 years) with a total of 53 breast lesions assessed by the Breast Imaging Reporting and Data System. They were enrolled under the following criteria: breast lesions larger than 1 cm in diameter which 1) were suspicious for malignancy on mammography or ultrasound (US), 2) were pathologically confirmed to be breast cancer with US-guided core-needle biopsy (CNB) 3) underwent 3 Tesla MRI with dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) and positron emission tomography-computed tomography (PET-CT), and 4) had an attainable immunohistochemistry profile from CNB. We acquired spectral data by HR-MAS MRS with CNB specimens and expressed the data as relative metabolite concentrations. We compared the metabolites with the signal enhancement ratio (SER), maximum standardized FDG uptake value (SUV max), apparent diffusion coefficient (ADC), and histopathologic prognostic factors for correlation. We calculated Spearman correlations and performed a partial least squares-discriminant analysis (PLS-DA) to further classify patient groups into subgroups to find correlation differences between HR-MAS spectroscopic values and conventional imaging parameters. Results In a multivariate analysis, the PLS-DA models built with HR-MAS MRS metabolic profiles showed visible discrimination between high and low SER, SUV, and ADC. In luminal subtype breast cancer, compared to all cases, high SER, ADV, and SUV were more closely clustered by visual assessment. Multiple metabolites were correlated with SER and SUV in

  8. 1H-13C/1H-15N Heteronuclear Dipolar Recoupling by R-Symmetry Sequences Under Fast Magic Angle Spinning for Dynamics Analysis of Biological and Organic Solids

    PubMed Central

    Hou, Guangjin; Byeon, In-Ja L.; Ahn, Jinwoo; Gronenborn, Angela M.; Polenova, Tatyana

    2011-01-01

    Fast magic angle spinning (MAS) NMR spectroscopy is becoming increasingly important in structural and dynamics studies of biological systems and inorganic materials. Superior spectral resolution due to the efficient averaging of the dipolar couplings can be attained at MAS frequencies of 40 kHz and higher with appropriate decoupling techniques, while proton detection gives rise to significant sensitivity gains, therefore making fast MAS conditions advantageous across the board compared with the conventional slow- and moderate-MAS approaches. At the same time, many of the dipolar recoupling approaches that currently constitute the basis for structural and dynamics studies of solid materials and that are designed for MAS frequencies of 20 kHz and below, fail above 30 kHz. In this report, we present an approach for 1H-13C/1H-15N heteronuclear dipolar recoupling under fast MAS conditions using R-type symmetry sequences, which is suitable even for fully protonated systems. A series of rotor-synchronized R-type symmetry pulse schemes are explored for the determination of structure and dynamics in biological and organic systems. The investigations of the performance of the various RNnv-symmetry sequences at the MAS frequency of 40 kHz experimentally and by numerical simulations on [U-13C,15N]-alanine and [U-13C,15N]-N-acetyl-valine, revealed excellent performance for sequences with high symmetry number ratio (N/2n > 2.5). Further applications of this approach are presented for two proteins, sparsely 13C/uniformly 15N enriched CAP-Gly domain of dynactin and U-13C,15N-Tyr enriched C-terminal domain of HIV-1 CA protein. 2D and 3D R1632-based DIPSHIFT experiments carried out at the MAS frequency of 40 kHz, yielded site-specific 1H-13C/1H-15N heteronuclear dipolar coupling constants for CAP-Gly and CTD CA, reporting on the dynamic behavior of these proteins on time scales of nano- to microseconds. The R-symmetry based dipolar recoupling under fast MAS is expected to find

  9. A 1H/19F minicoil NMR probe for solid-state NMR: application to 5-fluoroindoles.

    PubMed

    Graether, Steffen P; DeVries, Jeffrey S; McDonald, Robert; Rakovszky, Melissa L; Sykes, Brian D

    2006-01-01

    We show that it is feasible to use a minicoil for solid-state 19F 1H NMR experiments that has short pulse widths, good RF homogeneity, and excellent signal-to-noise for small samples while using low power amplifiers typical to liquid-state NMR. The closely spaced resonant frequencies of 1H and 19F and the ubiquitous use of fluorine in modern plastics and electronic components present two major challenges in the design of a high-sensitivity, high-field 1H/19F probe. Through the selection of specific components, circuit design, and pulse sequence, we were able to build a probe that has low 19F background and excellent separation of 1H and 19F signals. We determine the principle components of the chemical shift anisotropy tensor of 5-fluoroindole-3-acetic acid (5FIAA) and 5-fluorotryptophan. We also solve the crystal structure of 5FIAA, determine the orientation dependence of the chemical shift of a single crystal of 5FIAA, and predict the 19F chemical shift based on the orientation of the fluorine in the crystal. The results show that this 1H/19F probe is suitable for solid-state NMR experiments with low amounts of biological molecules that have been labeled with 19F. PMID:16198131

  10. Impurity effect of the Λ particle on the structure of 18F and Λ19F

    NASA Astrophysics Data System (ADS)

    Tanimura, Y.; Hagino, K.; Sagawa, H.

    2012-10-01

    We perform three-body model calculations for a sd-shell hypernucleus Λ19F (Λ17O+p+n) and its core nucleus 18F (16O+p+n), employing a density-dependent contact interaction between the valence proton and neutron. We find that the B(E2) value from the first excited state (with spin and parity of Iπ=3+) to the ground state (Iπ=1+) is slightly changed by the addition of a Λ particle, which exhibits the so called shrinkage effect of Λ particle. We also show that the excitation energy of the 3+ state is reduced in Λ19F compared to 18F, as is observed in a p-shell nucleus 6Li. We discuss the mechanism of this reduction of the excitation energy, pointing out that it is caused by a different mechanism from that in Λ7Li.

  11. A Study on 19F( n,α) Reaction Cross Section

    NASA Astrophysics Data System (ADS)

    Uğur, F. A.; Tel, E.; Gökçe, A. A.

    2013-06-01

    In this study, cross sections of neutron induced reactions have been investigated for fluorine target nucleus. The calculations have been made on the excitation functions of 19F ( n,α), 19F( n,xα) reactions. Fluorine (F) and its molten salt compounds (LiF) can serve as a coolant which can be used at high temperatures without reaching a high vapor pressure and also the molten salt compounds are also a good neutron moderator. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the full exciton model and the cascade exciton model. The equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, reaction cross sections have calculated by using evaluated empirical formulas developed by Tel et al. at 14-15 MeV energy. The obtained results have been discussed and compared with the available experimental data.

  12. Fission fragment angular distributions for 11B and 19F+238U systems

    NASA Astrophysics Data System (ADS)

    Karnik, A.; Kailas, S.; Chatterjee, A.; Navin, A.; Shrivastava, A.; Singh, P.; Samant, M. S.

    1995-12-01

    The fission fragment angular distributions were measured at energies above the fusion barrier, for the systems 11B and 19F + 238U. An analysis of the present data along with those already available for the systems 6,7Li, 12C, and 16O + 238U was made in terms of the saddle-point statistical model. While the anisotropies were ``normal'' for 6,7Li, 11B, 12C+238U systems, the ones for 16O and 19F+238U systems were found to be ``anomalous.'' The entrance channel mass asymmetry dependence of the anisotropies as observed here is consistent with the expectations of preequilibrium fission dynamics. This result emphasizes the importance of preequilibrium fission in heavy-ion induced fusion-fission reactions.

  13. Tracking Transitions in Spider Wrapping Silk Conformation and Dynamics by (19)F Nuclear Magnetic Resonance Spectroscopy.

    PubMed

    Sarker, Muzaddid; Orrell, Kathleen E; Xu, Lingling; Tremblay, Marie-Laurence; Bak, Jessi J; Liu, Xiang-Qin; Rainey, Jan K

    2016-05-31

    Aciniform silk protein (AcSp1) is the primary component of wrapping silk, the toughest of the spider silks because of a combination of high tensile strength and extensibility. Argiope trifasciata AcSp1 contains a core repetitive domain with at least 14 homogeneous 200-amino acid units ("W" units). Upon fibrillogenesis, AcSp1 converts from an α-helix-rich soluble state to a mixed α-helical/β-sheet conformation. Solution-state nuclear magnetic resonance (NMR) spectroscopy allowed demonstration of variable local stability within the W unit, but comprehensive characterization was confounded by spectral overlap, which was exacerbated by decreased chemical shift dispersion upon denaturation. Here, (19)F NMR spectroscopy, in the context of a single W unit (W1), is applied to track changes in structure and dynamics. Four strategic positions in the W unit were mutated to tryptophan and biosynthetically labeled with 5-fluorotryptophan (5F-Trp). Simulated annealing-based structure calculations implied that these substitutions should be tolerated, while circular dichroism (CD) spectroscopy and (1)H-(15)N chemical shift displacements indicated minimal structural perturbation in W1 mutants. Fiber formation by W2 concatemers containing 5F-Trp substitutions in both W units demonstrated retention of functionality, a somewhat surprising finding in light of sequence conservation between species. Each 5F-Trp-labeled W1 exhibited a unique (19)F chemical shift, line width, longitudinal relaxation time constant (T1), and solvent isotope shift. Perturbation to (19)F chemical shift and nuclear spin relaxation parameters reflected changes in the conformation and dynamics at each 5F-Trp site upon addition of urea and dodecylphosphocholine (DPC). (19)F NMR spectroscopy allowed unambiguous localized tracking throughout titration with each perturbant, demonstrating distinct behavior for each perturbant not previously revealed by heteronuclear NMR experiments. PMID:27153372

  14. Bulk magnetic susceptibility induced broadening in the 19F NMR of suspended leukemic cells.

    PubMed

    Adebodun, F; Post, J F

    1993-01-01

    The relevance of bulk magnetic susceptibility (BMS) induced broadening to in vivo NMR studies of intact cells has been examined and the significance of the contribution of BMS difference to the resolution of intra- and extracellular resonances was demonstrated. BMS difference between intra- and extracellular compartments was found to limit the resolution of intra- and extracellular 19F resonances of fluoro compounds in leukemic cells. PMID:8499242

  15. Parallel NMR spectroscopy with simultaneous detection of (1) H and (19) F nuclei.

    PubMed

    Kovacs, Helena; Kupče, Ēriks

    2016-07-01

    Recording NMR signals of several nuclear species simultaneously by using parallel receivers provides more information from a single measurement and at the same time increases the measurement sensitivity per unit time. Here we present a comprehensive series of the most frequently used NMR experiments modified for simultaneous direct detection of two of the most sensitive NMR nuclei - (1) H and (19) F. We hope that the presented material will stimulate interest in and further development of this technique. PMID:27021630

  16. Amphiphilic Hyperbranched Fluoropolymers as Nanoscopic 19F-Magnetic Resonance Imaging Agent Assemblies

    PubMed Central

    Du, Wenjun; Nyström, Andreas M.; Zhang, Lei; Powell, Kenya T.; Li, Yali; Cheng, Chong; Wickline, Samuel A.; Wooley, Karen L.

    2009-01-01

    Three hyperbranched fluoropolymers were synthesized and their micelles were constructed as potential 19F MRI agents. A hyperbranched star-like core was first synthesized via ATR-SCVCP of 4-chloromethyl styrene (CMS), lauryl acrylate (LA) and 1,1,1-tris(4′-(2″-bromoisobutyryloxy)phenyl)ethane (TBBPE). The polymerization gave a small core with Mn of 5.5 kDa with PDI of 1.6, which served as a macroinitiator. Trifluoroethyl methacrylate (TFEMA) and tert-butyl acrylate (tBA) in different ratio were then “grafted” from the core to give three polymers with Mn of ca. 120 kDa and PDI values of ca. 1.6–1.8. After acidolysis of the tert-butyl ester groups, amphiphilic, hyperbranched star-like polymers with Mn of ca. 100 kDa were obtained. These structures were subjected to micelle formation in aqueous solution to give micelles having TEM-measured diameters ranging from 3–8 nm and DLS-measured hydrodynamic diameters from 20–30 nm. These micelles gave a narrow, single resonance by 19F NMR spectroscopy, with a half width of approximately 130 Hz. The T1/T2 parameters were ca. 500 ms and 50 ms, respectively, and were not significantly affected by the composition and sizes of the micelles. 19F MRI phantom images of these fluorinated micelles were acquired, which demonstrated that these fluorinated micelles maybe useful as novel 19F MRI agents for a variety of biomedical studies. PMID:18795785

  17. Discovering the Magic of Magic Squares

    ERIC Educational Resources Information Center

    Semanisinova, Ingrid; Trenkler, Marian

    2007-01-01

    The purpose of this article is to present a collection of problems that allow students to investigate magic squares and Latin squares, formulate their own conjectures about these mathematical objects, look for arguments supporting or disproving their conjectures, and finally establish and prove mathematical assertions. Each problem is completed…

  18. Single 19F Probe for Simultaneous Detection of Multiple Metal Ions Using miCEST MRI

    PubMed Central

    2015-01-01

    The local presence and concentration of metal ions in biological systems has been extensively studied ex vivo using fluorescent dyes. However, the detection of multiple metal ions in vivo remains a major challenge. We present a magnetic resonance imaging (MRI)-based method for noninvasive detection of specific ions that may be coexisting, using the tetrafluorinated derivative of the BAPTA (TF-BAPTA) chelate as a 19F chelate analogue of existing optical dyes. Taking advantage of the difference in the ion-specific 19F nuclear magnetic resonance (NMR) chemical shift offset (Δω) values between the ion-bound and free TF-BAPTA, we exploited the dynamic exchange between ion-bound and free TF-BAPTA to obtain MRI contrast with multi-ion chemical exchange saturation transfer (miCEST). We demonstrate that TF-BAPTA as a prototype single 19F probe can be used to separately visualize mixed Zn2+ and Fe2+ ions in a specific and simultaneous fashion, without interference from potential competitive ions. PMID:25523816

  19. Dark matter spin-dependent limits for WIMP interactions on 19F by PICASSO

    NASA Astrophysics Data System (ADS)

    Archambault, S.; Aubin, F.; Auger, M.; Behnke, E.; Beltran, B.; Clark, K.; Dai, X.; Davour, A.; Farine, J.; Faust, R.; Genest, M.-H.; Giroux, G.; Gornea, R.; Krauss, C.; Kumaratunga, S.; Lawson, I.; Leroy, C.; Lessard, L.; Levy, C.; Levine, I.; MacDonald, R.; Martin, J.-P.; Nadeau, P.; Noble, A.; Piro, M.-C.; Pospisil, S.; Shepherd, T.; Starinski, N.; Stekl, I.; Storey, C.; Wichoski, U.; Zacek, V.

    2009-11-01

    The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on 19F using the superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the rejection of non-particle induced events are described. First results are presented for a subset of two detectors with target masses of 19F of 65 g and 69 g respectively and a total exposure of 13.75 ± 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV /c2 new limits have been obtained on the spin-dependent cross section on 19F of σF = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of σp = 0.16 pb and σn = 2.60 pb respectively (90% C.L.). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.

  20. (19)F Magnetic Resonance Imaging Signals from Peptide Amphiphile Nanostructures Are Strongly Affected by Their Shape.

    PubMed

    Preslar, Adam T; Tantakitti, Faifan; Park, Kitae; Zhang, Shanrong; Stupp, Samuel I; Meade, Thomas J

    2016-08-23

    Magnetic resonance imaging (MRI) is a noninvasive imaging modality that provides excellent spatial and temporal resolution. The most commonly used MR probes face significant challenges originating from the endogenous (1)H background signal of water. In contrast, fluorine MRI ((19)F MRI) allows quantitative probe imaging with zero background signal. Probes with high fluorine content are required for high sensitivity, suggesting nanoscale supramolecular assemblies containing (19)F probes offer a potentially useful strategy for optimum imaging as a result of improved payload. We report here on supramolecular nanostructures formed by fluorinated peptide amphiphiles containing either glutamic acid or lysine residues in their sequence. We identified molecules that form aggregates in water which transition from cylindrical to ribbon-like shape as pH increased from 4.5 to 8.0. Interestingly, we found that ribbon-like nanostructures had reduced magnetic resonance signal, whereas their cylindrical counterparts exhibited strong signals. We attribute this drastic difference to the greater mobility of fluorinated tails in the hydrophobic compartment of cylindrical nanostructures compared to lower mobility in ribbon-like assemblies. This discovery identifies a strategy to design supramolecular, self-assembling contrast agents for (19)F MRI that can spatially map physiologically relevant changes in pH using changes in morphology. PMID:27425636

  1. Spinning angle optical calibration apparatus

    DOEpatents

    Beer, Stephen K.; Pratt, II, Harold R.

    1991-01-01

    An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting an accurate reproducing of spinning "magic angles" in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the "magic angle" of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning "magic angle" of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position.

  2. About Magic Rectangles

    ERIC Educational Resources Information Center

    Hakopian, Yuri R.; Eloyan, Ani N.; Khachatryan, David E.

    2006-01-01

    This paper introduces a class of matrices, the rows and columns of which add up to identical constants (generally speaking, different for rows and columns). Some properties of these matrices, which will be called "magic rectangles" are discussed.

  3. Let's Make Magic.

    ERIC Educational Resources Information Center

    Bang-Jensen, Valerie

    1986-01-01

    A learning experience designed to expand primary students' knowledge of what is and is not magic is described. Included are activities involving language arts, math, art, class discussion, and motor skills. (MT)

  4. Science, Magic, and Culture

    ERIC Educational Resources Information Center

    Wangler, David G.

    1974-01-01

    The differences which appear when a heavily scientific culture comes in contact with a culture whose basic orientation toward nature and man is of a religious, magical character are briefly investigated. (NQ)

  5. Strategies to enhance signal intensity with paramagnetic fluorine-labelled lanthanide complexes as probes for 19F magnetic resonance.

    PubMed

    Chalmers, Kirsten H; Botta, Mauro; Parker, David

    2011-01-28

    The synthesis and (19)F NMR spectroscopic properties are reported for three series of CF(3)-labelled lanthanide(III) complexes, based on mono- and diamide cyclen ligands. Analyses of variable temperature, pH and field (19)F, (17)O and (1)H NMR spectroscopic experiments are reported and the merits of a triphosphinate mono-amide complex defined by virtue of its favourable isomer distribution and attractive relaxation properties. These lead to an enhanced sensitivity of detection in (19)F magnetic resonance experiments versus a diamagnetic Y(III) analogue, paving the way for future shift and imaging studies. PMID:21127807

  6. Fluorinated Boronic Acid-Appended Bipyridinium Salts for Diol Recognition and Discrimination via (19)F NMR Barcodes.

    PubMed

    Axthelm, Jörg; Görls, Helmar; Schubert, Ulrich S; Schiller, Alexander

    2015-12-16

    Fluorinated boronic acid-appended benzyl bipyridinium salts, derived from 4,4'-, 3,4'-, and 3,3'-bipyridines, were synthesized and used to detect and differentiate diol-containing analytes at physiological conditions via (19)F NMR spectroscopy. An array of three water-soluble boronic acid receptors in combination with (19)F NMR spectroscopy discriminates nine diol-containing bioanalytes--catechol, dopamine, fructose, glucose, glucose-1-phosphate, glucose-6-phosphate, galactose, lactose, and sucrose--at low mM concentrations. Characteristic (19)F NMR fingerprints are interpreted as two-dimensional barcodes without the need of multivariate analysis techniques. PMID:26595191

  7. TANKS 18 AND 19-F EQUIPMENT GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS

    SciTech Connect

    Stefanko, D.; Langton, C.

    2011-12-15

    The United States Department of Energy (US DOE) intends to remove Tanks 18-F and 19-F at the Savannah River Site (SRS) from service. The high-level waste (HLW) tanks have been isolated from the F-area Tank Farm (FTF) facilities and will be filled with cementitious grout for the purpose of: (1) physically stabilizing the empty volumes in the tanks, (2) limiting/eliminating vertical pathways from the surface to residual waste on the bottom of the tanks, (3) providing an intruder barrier, and (4) providing an alkaline, chemical reducing environment within the closure boundary to limit solubility of residual radionuclides. Bulk waste and heel waste removal equipment will remain in Tanks 18-F and 19-F when the tanks are closed. This equipment includes: mixer pumps, transfer pumps, transfer jets, equipment support masts, sampling masts and dip tube assemblies. The current Tank 18-F and 19-F closure strategy is to grout the internal void spaces in this equipment to eliminate fast vertical pathways and slow water infiltration to the residual material on the tank floor. This report documents the results of laboratory testing performed to identify a grout formulation for filling the abandoned equipment in Tanks 18-F and 19-F. The objective of this work was to formulate a flowable grout for filling internal voids of equipment that will remain in Tanks 18-F and 19-F during the final closures. This work was requested by V. A. Chander, Tank Farm Closure Engineering, in HLW-TTR-2011-008. The scope for this task is provided in the Task Technical and Quality Assurance Plan (TTQAP), SRNL-RP-2011-00587. The specific objectives of this task were to: (1) Prepare and evaluate the SRR cooling coil grout identified in WSRC-STI-2008-00298 per the TTR for this work. The cooling coil grout is a mixture of BASF MasterFlow{reg_sign} 816 cable grout (67.67 wt. %), Grade 100 ground granulated blast furnace slag (7.52 wt. %) and water (24.81 wt. %); (2) Identify equipment grout placement and

  8. Quantitative Tissue Oxygen Measurement in Multiple Organs Using 19F MRI in a Rat Model

    PubMed Central

    Liu, Siyuan; Shah, Sameer J.; Wilmes, Lisa J.; Feiner, John; Kodibagkar, Vikram D.; Wendland, Michael F.; Mason, Ralph P.; Hylton, Nola; Hopf, Harriet W.; Rollins, Mark D.

    2011-01-01

    Measurement of individual organ tissue oxygen levels can provide information to help evaluate and optimize medical interventions in many areas including wound healing, resuscitation strategies, and cancer therapeutics. Echo planar 19F MRI has previously focused on tumor oxygen measurement at low oxygen levels (pO2) < 30 mmHg. It uses the linear relationship between spin-lattice relaxation rate (R1) of hexafluorobenzene (HFB) and pO2. The feasibility of this technique for a wider range of pO2 values and individual organ tissue pO2 measurement was investigated in a rat model. Spin-lattice relaxation times (T1=1/R1) of HFB were measured using 19F saturation recovery echo planar imaging (EPI). Initial in vitro studies validated the linear relationship between R1 and pO2 from 0 mmHg to 760 mmHg oxygen partial pressure at 25°C, 37°C, and 41°C at 7 Tesla for HFB. In vivo experiments measured rat tissue oxygen (ptO2) levels of brain, kidney, liver, gut, muscle and skin during inhalation of both 30% and 100% oxygen. All organ ptO2 values significantly increased with hyperoxia (p<0.001). This study demonstrates that 19F MRI of HFB offers a feasible tool to measure regional ptO2 in vivo, and that hyperoxia significantly increases ptO2 of multiple organs in a rat model. PMID:21688315

  9. Solid-state (19)F-NMR of peptides in native membranes.

    PubMed

    Koch, Katja; Afonin, Sergii; Ieronimo, Marco; Berditsch, Marina; Ulrich, Anne S

    2012-01-01

    To understand how membrane-active peptides (MAPs) function in vivo, it is essential to obtain structural information about them in their membrane-bound state. Most biophysical approaches rely on the use of bilayers prepared from synthetic phospholipids, i.e. artificial model membranes. A particularly successful structural method is solid-state NMR, which makes use of macroscopically oriented lipid bilayers to study selectively isotope-labelled peptides. Native biomembranes, however, have a far more complex lipid composition and a significant non-lipidic content (protein and carbohydrate). Model membranes, therefore, are not really adequate to address questions concerning for example the selectivity of these membranolytic peptides against prokaryotic vs eukaryotic cells, their varying activities against different bacterial strains, or other related biological issues.Here, we discuss a solid-state (19)F-NMR approach that has been developed for structural studies of MAPs in lipid bilayers, and how this can be translated to measurements in native biomembranes. We review the essentials of the methodology and discuss key objectives in the practice of (19)F-labelling of peptides. Furthermore, the preparation of macroscopically oriented biomembranes on solid supports is discussed in the context of other membrane models. Two native biomembrane systems are presented as examples: human erythrocyte ghosts as representatives of eukaryotic cell membranes, and protoplasts from Micrococcus luteus as membranes from Gram-positive bacteria. Based on our latest experimental experience with the antimicrobial peptide gramicidin S, the benefits and some implicit drawbacks of using such supported native membranes in solid-state (19)F-NMR analysis are discussed. PMID:21598096

  10. Cerebral blood flow in experimental ischemia assessed by sup 19 F magnetic resonance spectroscopy in cats

    SciTech Connect

    Brunetti, A.; Nagashima, G.; Bizzi, A.; DesPres, D.J. )

    1990-10-01

    We evaluated a 19F magnetic resonance spectroscopic technique that detects Freon-23 washout as a means of measuring cerebral blood flow in halothane-anesthetized adult cats during and after transient cerebral ischemia produced by vascular occlusion. The experiments were performed to test the ability of this recently developed method to detect postischemic flow deficits. Results were consistent with postischemic hypoperfusion. The method also proved valuable for measuring small residual flow during vascular occlusion. Our experiments indicate that this method provides simple, rapid, and repeatable flow measurements that can augment magnetic resonance examinations of cerebral metabolic parameters in the study of ischemia.

  11. Measuring 19F(α,n) with VANDLE for Nuclear Safeguards

    NASA Astrophysics Data System (ADS)

    Peters, William; Clement, R. C. C.; Smith, M. S.; Pain, S. D.; Thompson, S.; Cizewski, J. A.; Reingold, C.; Manning, B.; Burcher, S.; Bardayan, D. W.; Tan, W.-P.; Stech, E.; Smith, M. K.; Smith, K.; Avetisyan, R.; Long, A.; Battaglia, A.; Marley, S.; Gyurjinyan, A.; Ilyushkin, S.; O'Malley, P. D.; Madurga, M.; Paulauskas, S. V.; Taylor, S.; Febbraro, M.

    2014-09-01

    UF6 is used in many parts of the Uranium Fuel Cycle, and various techniques are used by nonproliferation agencies to monitor and account for the material. One of the most promising non-destructive assay (NDA) methods consists of measuring gross neutron rates induced by uranium-decay alpha particles reacting with the fluorine and emitting a neutron. This method, however, currently lacks reliable nuclear data on the 19F(α,n) reaction cross section to determine an accurate neutron yield rate for a given sample of UF6. We have used the Versatile Array of Neutron Detectors at Low Energy (VANDLE) to measure the cross section and coincident neutron spectrum over an energy range pertinent to NDA in a two part experiment: First at Notre Dame with a LaF3 target and a pulsed alpha-particle beam, and second at ORNL with a windowless He-gas target and a 19F beam. The motivation for this measurement and preliminary results will be presented. UF6 is used in many parts of the Uranium Fuel Cycle, and various techniques are used by nonproliferation agencies to monitor and account for the material. One of the most promising non-destructive assay (NDA) methods consists of measuring gross neutron rates induced by uranium-decay alpha particles reacting with the fluorine and emitting a neutron. This method, however, currently lacks reliable nuclear data on the 19F(α,n) reaction cross section to determine an accurate neutron yield rate for a given sample of UF6. We have used the Versatile Array of Neutron Detectors at Low Energy (VANDLE) to measure the cross section and coincident neutron spectrum over an energy range pertinent to NDA in a two part experiment: First at Notre Dame with a LaF3 target and a pulsed alpha-particle beam, and second at ORNL with a windowless He-gas target and a 19F beam. The motivation for this measurement and preliminary results will be presented. This work is funded in part by NSF Grant 1068192, DOE Office of Science, and the NNSA Office of Defense Nuclear

  12. /sup 19/F shielding anisotropy in RbCaF/sub 3/

    SciTech Connect

    Kaliaperumal, R.; Sears, R.E.J.; Finch, C.B.

    1987-07-01

    A /sup 19/F NMR multipulse measurement of the chemical shift in a single crystal of cubic RbCaF/sub 3/ gave -47.0 +- 3 ppm as the isotropic value with respect to C/sub 6/F/sub 6/, and 128.7 +- 6 ppm as the anisotropy. The shielding is accounted for by the usual diamagnetic and paramagnetic ionic overlap and covalent terms. As a result, the Ca/sup + +/ -F/sup -/ bond is estimated to be 98% ionic. No significant spectral changes were found when the crystal was cooled below the cubic to tetragonal phase transition temperature. Reasons for this are given.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2014-10-18

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

  15. Fission fragment angular distributions for the system 19F+232Th

    NASA Astrophysics Data System (ADS)

    Kailas, S.; Navin, A.; Chatterjee, A.; Singh, P.; Choudhury, R. K.; Saxena, A.; Nadkarni, D. M.; Kapoor, S. S.; Ramamurthy, V. S.; Nayak, B. K.; Suryanarayana, S. V.

    1991-03-01

    The fission fragment angular distributions for the system 19F+232Th have been measured at several bombarding energies between 94 and 108 MeV. Even though the anisotropy values measured in the present work are considerably smaller than the ones reported by Zhang et al. for the same system at similar energies, they are still anomalous when compared with the predictions of the standard saddle-point statistical model and fit into the systematics of entrance-channel dependence of fission anisotropies reported by us earlier.

  16. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  17. Correlation between 19F environment and isotropic chemical shift in barium and calcium fluoroaluminates.

    PubMed

    Body, M; Silly, G; Legein, C; Buzaré, J-Y

    2004-04-19

    High-speed MAS (19)F NMR spectra are recorded and reconstructed for 10 compounds from BaF(2)-AlF(3) and CaF(2)-AlF(3) binary systems which leads to the determination of 77 isotropic (19)F chemical shifts in various environments. A first attribution of NMR lines is performed for 8 compounds using a superposition model as initially proposed by B. Bureau et al. The phenomenological parameters of this model are then refined to improve the NMR line assignment. A satisfactory reliability is reached with a root-mean-square (RMS) deviation between calculated and measured values equal to 6 ppm. The refined parameters are then successfully tested on alpha-BaCaAlF(7) whose structure was recently determined. Finally, the isotropic chemical shift ranges are defined for shared, unshared, and "free" fluorine atoms encountered in the investigated binary systems. So, the fluorine surroundings can be deduced from the NMR line positions in compounds whose structure is unknown. Such an approach can also be applied to fluoride glasses. PMID:15074964

  18. A comparative study of 1H and 19F Overhauser DNP in fluorinated benzenes.

    PubMed

    Neudert, Oliver; Mattea, Carlos; Spiess, Hans Wolfgang; Stapf, Siegfried; Münnemann, Kerstin

    2013-12-21

    Hyperpolarization techniques, such as Overhauser dynamic nuclear polarization (DNP), can provide a dramatic increase in the signal obtained from nuclear magnetic resonance experiments and may therefore enable new applications where sensitivity is a limiting factor. In this contribution, studies of the (1)H and (19)F Overhauser dynamic nuclear polarization enhancements at 345 mT are presented for three different aromatic solvents with the TEMPO radical for a range of radical concentrations. Furthermore, nuclear magnetic relaxation dispersion measurements of the same solutions are analyzed, showing contributions from dipolar and scalar coupling modulated by translational diffusion and different coupling efficiency for different solvents and nuclei. Measurements of the electron paramagnetic resonance linewidth are included to support the analysis of the DNP saturation factor for varying radical concentration. The results of our study give an insight into the characteristics of nitroxide radicals as polarizing agents for (19)F Overhauser DNP of aromatic fluorinated solvents. Furthermore, we compare our results with the findings of the extensive research on Overhauser DNP that was conducted in the past for a large variety of other radicals. PMID:24192645

  19. Study of fluorine in silicate glass with 19F nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Duncan, T. M.; Douglass, D. C.; Csencsits, R.; Walker, K. L.

    1986-07-01

    We report an application of nuclear magnetic resonance (NMR) spectroscopy to the study of fluorine-doped silicate glass prepared by the modified chemical vapor deposition process, prior to drawing the rod into fibers. The silica contains 1.03-wt. % fluorine, as determined by the calibrated intensity of the 19F NMR spectrum. The isotropic chemical shift of the 19F spectrum shows that fluorine bonds only to silicon; there is no evidence of oxyfluorides. Analysis of the distribution of nuclear dipolar couplings between fluorine nuclei reveals that the relative populations of silicon monofluoride sites [Si(O-)3F] and species having near-neighbor fluorines, such as silicon difluoride sites [Si(O-)2F2], are nearly statistically random. That is, to a good approximation, the fluorine substitutes randomly into the oxygen sites of the silica network. There is no evidence of local clusters of fluorine sites, silicon trifluoride sites [Si(O-)F3], or silicon tetrafluoride (SiF4).

  20. Measurement of the 19F(α,n)22Na Cross Section for Nuclear Safeguards Science

    NASA Astrophysics Data System (ADS)

    Lowe, Marcus; Smith, M. S.; Pain, S.; Febbraro, M.; Pittman, S.; Chipps, K. A.; Thompson, S. J.; Grinder, M.; Grzywacz, R.; Smith, K.; Thornsberry, C.; Thompson, P.; Peters, W. A.; Waddell, D.; Blanchard, R.; Carls, A.; Shadrick, S.; Engelhardt, A.; Hertz-Kintish, D.; Allen, N.; Sims, H.

    2015-10-01

    Enriched uranium is commonly stored in fluoride matrices such as UF6. Alpha decays of uranium in UF6 will create neutrons via the 19F(α,n)22Na reaction. An improved cross section for this reaction will enable improved nondestructive assays of uranium content in storage cylinders at material enrichment facilities. To determine this reaction cross section, we have performed experiments using both forward and inverse kinematic techniques at the University of Notre Dame (forward) and Oak Ridge National Laboratory (inverse). Both experiments utilized the Versatile Array of Neutron Detectors at Low Energy (VANDLE) for neutron detection. The ORNL experiment also used a new ionization chamber for 22Na particle identification. Gating on the 22Na nuclei detected drastically reduced the background counts in the neutron time-of-flight spectra. The latest analysis and results will be presented for 19F beam energies ranging from 20-37 MeV. This work is funded in part by the DOE Office of Nuclear Physics, the National Nuclear Security Administration's Office of Defense Nuclear Nonproliferation R&D, and the NSF.

  1. Dark matter spin-dependent limits for WIMP interactions on 19F by PICASSO

    NASA Astrophysics Data System (ADS)

    Beltran, Berta; Picasso Collaboration

    2010-01-01

    The PICASSO experiment at SNOLAB uses super-heated C4F10 droplets suspended in a gel as a target sensitive to WIMP-proton spin-dependent elastic scattering. The phase II setup has been improved substantially in sensitivity by using an array of 32 detectors with an active mass of ~65 g each and largely reduced background. First results are presented for a subset of two detectors with target masses of 19F of 65 g and 69 g respectively and a total exposure of 13.75 ± 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c2 new limits have been obtained on the spin-dependent cross section on 19F of σF = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of σp = 0.15 pb and σn = 2.45 pb respectively (90% C.L). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.

  2. {sup 19}F NMR measurements of NO production in hypertensive ISIAH and OXYS rats

    SciTech Connect

    Bobko, Andrey A. . E-mail: bobko@kinetics.nsc.ru; Sergeeva, Svetlana V.; Bagryanskaya, Elena G.; Markel, Arkadii L.; Khramtsov, Valery V.; Reznikov, Vladimir A.; Kolosova, Nataljya G.

    2005-05-06

    Recently we demonstrated the principal possibility of application of {sup 19}F NMR spin-trapping technique for in vivo {sup {center_dot}}NO detection [Free Radic. Biol. Med. 36 (2004) 248]. In the present study, we employed this method to elucidate the significance of {sup {center_dot}}NO availability in animal models of hypertension. In vivo {sup {center_dot}}NO-induced conversion of the hydroxylamine of the fluorinated nitronyl nitroxide (HNN) to the hydroxylamine of the iminonitroxide (HIN) in hypertensive ISIAH and OXYS rat strains and normotensive Wistar rat strain was measured. Significantly lower HIN/HNN ratios were measured in the blood of the hypertensive rats. The NMR data were found to positively correlate with the levels of nitrite/nitrate evaluated by Griess method and negatively correlate with the blood pressure. In comparison with other traditionally used methods {sup 19}F NMR spectroscopy allows in vivo evaluation of {sup {center_dot}}NO production and provides the basis for in vivo {sup {center_dot}}NO imaging.

  3. TANK 18-F AND 19-F TANK FILL GROUT SCALE UP TEST SUMMARY

    SciTech Connect

    Stefanko, D.; Langton, C.

    2012-01-03

    High-level waste (HLW) tanks 18-F and 19-F have been isolated from FTF facilities. To complete operational closure the tanks will be filled with grout for the purpose of: (1) physically stabilizing the tanks, (2) limiting/eliminating vertical pathways to residual waste, (3) entombing waste removal equipment, (4) discouraging future intrusion, and (5) providing an alkaline, chemical reducing environment within the closure boundary to control speciation and solubility of select radionuclides. This report documents the results of a four cubic yard bulk fill scale up test on the grout formulation recommended for filling Tanks 18-F and 19-F. Details of the scale up test are provided in a Test Plan. The work was authorized under a Technical Task Request (TTR), HLE-TTR-2011-008, and was performed according to Task Technical and Quality Assurance Plan (TTQAP), SRNL-RP-2011-00587. The bulk fill scale up test described in this report was intended to demonstrate proportioning, mixing, and transportation, of material produced in a full scale ready mix concrete batch plant. In addition, the material produced for the scale up test was characterized with respect to fresh properties, thermal properties, and compressive strength as a function of curing time.

  4. Dissection of the ion-induced folding of the hammerhead ribozyme using 19F NMR

    PubMed Central

    Hammann, Christian; Norman, David G.; Lilley, David M. J.

    2001-01-01

    We have used 19F NMR to analyze the metal ion-induced folding of the hammerhead ribozyme by selective incorporation of 5fluorouridine. We have studied the chemical shift and linewidths of 19F resonances of 5-fluorouridine at the 4 and 7 positions in the ribozyme core as a function of added Mg2+. The data fit well to a simple two-state model whereby the formation of domain 1 is induced by the noncooperative binding of Mg2+ with an association constant in the range of 100 to 500 M−1, depending on the concentration of monovalent ions present. The results are in excellent agreement with data reporting on changes in the global shape of the ribozyme. However, the NMR experiments exploit reporters located in the center of the RNA sections undergoing the folding transitions, thereby allowing the assignment of specific nucleotides to the separate stages. The results define the folding pathway at high resolution and provide a time scale for the first transition in the millisecond range. PMID:11331743

  5. Resolution of Oligomeric Species during the Aggregation of Aβ1-40 Using 19F NMR

    PubMed Central

    Suzuki, Yuta; Brender, Jeffrey R.; Soper, Molly T.; Krishnamoorthy, Janarthanan; Zhou, Yunlong; Ruotolo, Brandon T.; Kotov, Nicholas A.; Ramamoorthy, Ayyalusamy; Marsh, E. Neil G.

    2013-01-01

    In the commonly used nucleation-dependent model of protein aggregation, aggregation proceeds only after a lag phase in which the concentration of energetically unfavorable nuclei reaches a critical value. The formation of oligomeric species prior to aggregation can be difficult to detect by current spectroscopic techniques. By using real-time 19F NMR along with other techniques, we are able to show that multiple oligomeric species can be detected during the lag phase of Aβ1-40 fiber formation, consistent with a complex mechanism of aggregation. At least 6 types of oligomers can be detected by 19F NMR. These include the reversible formation of large β-sheet oligomer immediately after solubilization at high peptide concentration; a small oligomer that forms transiently during the early stages of the lag phase; and 4 spectroscopically distinct forms of oligomers with molecular weights between ~30–100 kDa that appear during the later stages of aggregation. The ability to resolve individual oligomers and track their formation in real-time should prove fruitful in understanding the aggregation of amyloidogenic proteins and in isolating potentially toxic non-amyloid oligomers. PMID:23445400

  6. Measured 19F(α,n) with VANDLE for Nuclear Safeguards

    NASA Astrophysics Data System (ADS)

    Peters, William; Clement, R. C. C.; Smith, M. S.; Pain, S.; Febbraro, M.; Pittman, S.; Thomspon, S.; Grinder, M.; Cizewski, J. A.; Reingold, C.; Manning, B.; Burcher, S.; Bardayan, D. W.; Tan, W.-P.; Stech, E.; Smith, M. K.; Avetisyan, R.; Gyurjinyan, A.; Lowe, M.; Ilyushkin, S.; Grzywacz, R.; Madurga, M.; Paulauskas, S. V.; Taylor, S. Z.; Smith, K.

    2015-10-01

    One of the most promising non-destructive assay (NDA) methods to monitor UF6 canisters consists of measuring gross neutron rates induced by uranium-decay alpha particles reacting with the fluorine and emitting a neutron. This method currently lacks reliable nuclear data on the 19F(α,n) reaction cross section to determine an accurate neutron yield rate for a given sample of UF6. We have measured the cross section and coincident neutron spectrum for the alpha-decay energy range using the VANDLE system. This experiment had two parts: first at Notre Dame with a LaF3 target and and a pulsed alpha-particle beam, and second at ORNL with a windowless He-gas target and a 19F beam. The motivation for this measurement and cross section results will be presented. This work is funded in part by the DOE Office of Science, the National Nuclear Security Administration SSAA and the Office of Defense Nuclear Nonproliferation R&D, and the NSF.

  7. Heteronuclear 19F-1H statistical total correlation spectroscopy as a tool in drug metabolism: study of flucloxacillin biotransformation.

    PubMed

    Keun, Hector C; Athersuch, Toby J; Beckonert, Olaf; Wang, Yulan; Saric, Jasmina; Shockcor, John P; Lindon, John C; Wilson, Ian D; Holmes, Elaine; Nicholson, Jeremy K

    2008-02-15

    We present a novel application of the heteronuclear statistical total correlation spectroscopy (HET-STOCSY) approach utilizing statistical correlation between one-dimensional 19F/1H NMR spectroscopic data sets collected in parallel to study drug metabolism. Parallel one-dimensional (1D) 800 MHz 1H and 753 MHz 19F{1H} spectra (n = 21) were obtained on urine samples collected from volunteers (n = 6) at various intervals up to 24 h after oral dosing with 500 mg of flucloxacillin. A variety of statistical relationships between and within the spectroscopic datasets were explored without significant loss of the typically high 1D spectral resolution, generating 1H-1H STOCSY plots, and novel 19F-1H HET-STOCSY, 19F-19F STOCSY, and 19F-edited 1H-1H STOCSY (X-STOCSY) spectroscopic maps, with a resolution of approximately 0.8 Hz/pt for both nuclei. The efficient statistical editing provided by these methods readily allowed the collection of drug metabolic data and assisted structure elucidation. This approach is of general applicability for studying the metabolism of other fluorine-containing drugs, including important anticancer agents such as 5-fluorouracil and flutamide, and is extendable to any drug metabolism study where there is a spin-active X-nucleus (e.g., 13C, 15N, 31P) label present. PMID:18211034

  8. TANK 18 AND 19-F TIER 1A EQUIPMENT FILL MOCK UP TEST SUMMARY

    SciTech Connect

    Stefanko, D.; Langton, C.

    2011-11-04

    The United States Department of Energy (US DOE) has determined that Tanks 18-F and 19-F have met the F-Tank Farm (FTF) General Closure Plan Requirements and are ready to be permanently closed. The high-level waste (HLW) tanks have been isolated from FTF facilities. To complete operational closure they will be filled with grout for the purpose of: (1) physically stabilizing the tanks, (2) limiting/eliminating vertical pathways to residual waste, (3) discouraging future intrusion, and (4) providing an alkaline, chemical reducing environment within the closure boundary to control speciation and solubility of select radionuclides. Bulk waste removal and heel removal equipment remain in Tanks 18-F and 19-F. This equipment includes the Advance Design Mixer Pump (ADMP), transfer pumps, transfer jets, standard slurry mixer pumps, equipment-support masts, sampling masts, dip tube assemblies and robotic crawlers. The present Tank 18 and 19-F closure strategy is to grout the equipment in place and eliminate vertical pathways by filling voids in the equipment to vertical fast pathways and water infiltration. The mock-up tests described in this report were intended to address placement issues identified for grouting the equipment that will be left in Tank 18-F and Tank 19-F. The Tank 18-F and 19-F closure strategy document states that one of the Performance Assessment (PA) requirements for a closed tank is that equipment remaining in the tank be filled to the extent practical and that vertical flow paths 1 inch and larger be grouted. The specific objectives of the Tier 1A equipment grout mock-up testing include: (1) Identifying the most limiting equipment configurations with respect to internal void space filling; (2) Specifying and constructing initial test geometries and forms that represent scaled boundary conditions; (3) Identifying a target grout rheology for evaluation in the scaled mock-up configurations; (4) Scaling-up production of a grout mix with the target rheology

  9. Magic and cognitive neuroscience.

    PubMed

    Quiroga, Rodrigo Quian

    2016-05-23

    In recent years, neuroscientists have shown an increasing interest in magic. One reason for this is the parallels that can be drawn between concepts that have long been discussed in magic theory, particularly misdirection, and those that are routinely studied in cognitive neuroscience, such as attention and, as argued in this essay, different forms of memory. A second and perhaps more attractive justification for this growing interest is that magic tricks offer novel experimental approaches to cognitive neuroscience. In fact, magicians continuously demonstrate in very engaging ways one of the most basic principles of brain function - how the brain constructs a subjective reality using assumptions based on relatively little and ambiguous information. PMID:27218839

  10. [Homeopathic medicine and magic].

    PubMed

    Angutek, Dorota

    2007-01-01

    The article compares homeopathic medicine and primitive magic. The author realises formal similarities beetwen these two fields of knowledge. The primitive homeopathic magic characterised by J. G. Frazer in his The Golden Bought announces that "similar courses similar". M. Mauss and H. Hubert added to this "low" an another formula: "similar acts on similar that courses a contrary phenomenon". The last formula is an identic one with the "low" of homeopathic medicine. Moreover there is a similarity between pantheistic religion of Hahnemann and magician beliefs in the power named mana in Melanesia and Polinesia or orenda, wakan, manitou and so on, by the Indians from The North America. The amazing thing is that homeopathic chemists belive that kinetic power transforms itself into esoteric one, during preparation of homeopathic medicines.In the end of this article the author ascertains that homeopathic medicine and magic has certain paradigm in common what is opposit to racionalism of official European paradigm of thinking. PMID:19244731

  11. Manufacturing Magic and Computational Creativity.

    PubMed

    Williams, Howard; McOwan, Peter W

    2016-01-01

    This paper describes techniques in computational creativity, blending mathematical modeling and psychological insight, to generate new magic tricks. The details of an explicit computational framework capable of creating new magic tricks are summarized, and evaluated against a range of contemporary theories about what constitutes a creative system. To allow further development of the proposed system we situate this approach to the generation of magic in the wider context of other areas of application in computational creativity in performance arts. We show how approaches in these domains could be incorporated to enhance future magic generation systems, and critically review possible future applications of such magic generating computers. PMID:27375533

  12. Manufacturing Magic and Computational Creativity

    PubMed Central

    Williams, Howard; McOwan, Peter W.

    2016-01-01

    This paper describes techniques in computational creativity, blending mathematical modeling and psychological insight, to generate new magic tricks. The details of an explicit computational framework capable of creating new magic tricks are summarized, and evaluated against a range of contemporary theories about what constitutes a creative system. To allow further development of the proposed system we situate this approach to the generation of magic in the wider context of other areas of application in computational creativity in performance arts. We show how approaches in these domains could be incorporated to enhance future magic generation systems, and critically review possible future applications of such magic generating computers. PMID:27375533

  13. Imaging of Intratumoral Inflammation during Oncolytic Virotherapy of Tumors by 19F-Magnetic Resonance Imaging (MRI)

    PubMed Central

    Hess, Michael; Hofmann, Elisabeth; Seubert, Carolin; Langbein-Laugwitz, Johanna; Gentschev, Ivaylo; Sturm, Volker Jörg Friedrich; Ye, Yuxiang; Kampf, Thomas; Jakob, Peter Michael; Szalay, Aladar A.

    2013-01-01

    Background Oncolytic virotherapy of tumors is an up-coming, promising therapeutic modality of cancer therapy. Unfortunately, non-invasive techniques to evaluate the inflammatory host response to treatment are rare. Here, we evaluate 19F magnetic resonance imaging (MRI) which enables the non-invasive visualization of inflammatory processes in pathological conditions by the use of perfluorocarbon nanoemulsions (PFC) for monitoring of oncolytic virotherapy. Methodology/Principal Findings The Vaccinia virus strain GLV-1h68 was used as an oncolytic agent for the treatment of different tumor models. Systemic application of PFC emulsions followed by 1H/19F MRI of mock-infected and GLV-1h68-infected tumor-bearing mice revealed a significant accumulation of the 19F signal in the tumor rim of virus-treated mice. Histological examination of tumors confirmed a similar spatial distribution of the 19F signal hot spots and CD68+-macrophages. Thereby, the CD68+-macrophages encapsulate the GFP-positive viral infection foci. In multiple tumor models, we specifically visualized early inflammatory cell recruitment in Vaccinia virus colonized tumors. Furthermore, we documented that the 19F signal correlated with the extent of viral spreading within tumors. Conclusions/Significance These results suggest 19F MRI as a non-invasive methodology to document the tumor-associated host immune response as well as the extent of intratumoral viral replication. Thus, 19F MRI represents a new platform to non-invasively investigate the role of the host immune response for therapeutic outcome of oncolytic virotherapy and individual patient response. PMID:23441176

  14. The "magical" language of Mantra.

    PubMed

    Burchett, Patton E

    2008-01-01

    This paper aims to illuminate the phenomenon of mantras and to critique the category of magic through an examination of mantra as magical language. Mantras have often been referred to as "magic formulas" or "spells," yet one searches the scholarly literature in vain for a worthy explanation of precisely why mantra should or should not be considered magical. This essay addresses this lack, (a) explaining how mantra's conflict with modern Western understandings of language has led scholars to conceive of mantra as magic and (b) showing just what is at stake in such characterizations. This examination of mantra will demonstrate how "magic" and related terms have consistently been used not so much to describe as to marginalize and de-authorize that to which they refer. While the issue is partly about flawed terms and categories, the question of mantra as magic ultimately leads to an unsettling confrontation with the limits of our own modern rationalist perspective. PMID:20827826

  15. Neuroscience, Magic, and Counseling

    ERIC Educational Resources Information Center

    Echterling, Lennis G.; Presbury, Jack; Cowan, Eric

    2012-01-01

    Recent findings in neuroscience have identified principles, such as attention management and change blindness, which stage magicians exploit to create illusions. Neuroscientists have also revealed how mirror neurons and oxytocin enhance the impact of magic. In other words, magicians are just as much practitioners of sleight of mind as they are of…

  16. Magical Ideation and Schizophrenia.

    ERIC Educational Resources Information Center

    George, Leonard; Neufeld, Richard W. J.

    1987-01-01

    Administered the Eckblad and Chapman (1983) Magical Ideation Scale to groups of paranoid and nonparanoid schizophrenics and control subjects. Schizophrenics scored significantly higher than nonschizophrenic patients (mainly cases of affective disorder) and normal control subjects. Discusses theoretical and prognostic utility of this finding.…

  17. Helping, Manipulation, and Magic

    ERIC Educational Resources Information Center

    Frey, Louise A.; Edinburg, Golda M.

    1978-01-01

    The thesis of this article is that an understanding of the primitive origins of the helping process in myth, magic, and ritual may prevent social workers from engaging in practices that negate their clients' ability to work out their own solutions to problems. (Author)

  18. Sugar Cane Magic.

    ERIC Educational Resources Information Center

    Mower, Nancy Alpert

    The booklet contains a story for middle-grade students which shows how the roles of men and women change through the years. The main characters are three sixth graders in Hawaii: one girl has Hawaiian ancestors, one girl has Japanese ancestors, and one boy has New England missionary ancestors. The children discover a magic stalk of sugar cane…

  19. Thawing Out Some Magic

    ERIC Educational Resources Information Center

    Hippler, Arthur E.

    1975-01-01

    Psychiatrists have learned that delivering mental health services in a culture long dominated by magical thinking is not easy. Article discussed the problem of bringing the Eskimo into the care of the Alaska Psychiatric Institute and contemporary society. (Editor/RK)

  20. Magic, Morals and Health

    ERIC Educational Resources Information Center

    Johnson, Warren R.

    2010-01-01

    Magic has to do with the supernatural and the unnatural. It is indifferent to natural law and science and is aloof from scientific inquiry. Its existence depends upon unquestioning faith. Granted such faith, it is extraordinarily potent. If it does not move mountains, it convinces the faithful that it can. It can damage health and perhaps, restore…

  1. 19F NMR measurements of the rotational mobility of proteins in vivo.

    PubMed Central

    Williams, S P; Haggie, P M; Brindle, K M

    1997-01-01

    Three glycolytic enzymes, hexokinase, phosphoglycerate kinase, and pyruvate kinase, were fluorine labeled in the yeast Saccharomyces cerevisiae by biosynthetic incorporation of 5-fluorotryptophan. 19F NMR longitudinal relaxation time measurements on the labeled enzymes were used to assess their rotational mobility in the intact cell. Comparison with the results obtained from relaxation time measurements of the purified enzymes in vitro and from theoretical calculations showed that two of the labeled enzymes, phosphoglycerate kinase and hexokinase, were tumbling in a cytoplasm that had a viscosity approximately twice that of water. There were no detectable signals from pyruvate kinase in vivo, although it could be detected in diluted cell extracts, indicating that there was some degree of motional restriction of the enzyme in the intact cell. PMID:8994636

  2. Measurement of the 19F(α,n) Cross Section for Nuclear Safeguards Science

    NASA Astrophysics Data System (ADS)

    Reingold, C. S.; Cizewski, J. A.; Peters, W. A.; Clement, R. R. C.; Bardayan, D. W.; Smith, M. S.; Stech, E.; Strauss, S.; Tan, W. P.; Wiescher, M.; Madurga, M.; Vandle Collaboration

    2013-10-01

    A precise measurement of the 19F(α,n) cross section will improve Non Destructive Assays (NDA) of UF6 and other actinide-fluoride samples via neutron detection techniques. We will determine the cross section with two complementary approaches. First, we will bombard a LaF3 target with a pulsed 4He beam from the Notre Dame FN tandem accelerator; second, we will send a fluorine beam from the ORNL tandem through a pure helium gas target. The neutron spectra from both of these reactions will be measured using the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and coincident γ rays with a HPGe detector. We report here on data taken with VANDLE and a HPGe detector on a LaF3 target. My poster outlines the motivation for this experiment, explains the stages of this experiment, the current experimental setup, and preliminary data. This work is supported by the NNSA.

  3. Tanks 18 And 19-F Structural Flowable Grout Fill Material Evaluation And Recommendations

    SciTech Connect

    Langton, C. A.; Stefanko, D. B.

    2013-04-23

    Cementitious grout will be used to close Tanks 18-F and 19-F. The functions of the grout are to: 1) physically stabilize the final landfill by filling the empty volume in the tanks with a non-compressible material; 2) provide a barrier for inadvertent intrusion into the tank; 3) reduce contaminant mobility by a) limiting the hydraulic conductivity of the closed tank and b) reducing contact between the residual waste and infiltrating water; and 4) providing an alkaline, chemically reducing environment in the closed tank to control speciation and solubility of selected radionuclides. The objective of this work was to identify a single (all-in-one) grout to stabilize and isolate the residual radionuclides in the tank, provide structural stability of the closed tank and serve as an inadvertent intruder barrier. This work was requested by V. A. Chander, High Level Waste (HLW) Tank Engineering, in HLW-TTR-2011-008. The complete task scope is provided in the Task Technical and QA Plan, SRNL-RP-2011-00587 Revision 0. The specific objectives of this task were to: 1) Identify new admixtures and dosages for formulating a zero bleed flowable tank fill material selected by HLW Tank Closure Project personnel based on earlier tank fill studies performed in 2007. The chemical admixtures used for adjusting the flow properties needed to be updated because the original admixture products are no longer available. Also, the sources of cement and fly ash have changed, and Portland cements currently available contain up to 5 wt. % limestone (calcium carbonate). 2) Prepare and evaluate the placement, compressive strength, and thermal properties of the selected formulation with new admixture dosages. 3) Identify opportunities for improving the mix selected by HLW Closure Project personnel and prepare and evaluate two potentially improved zero bleed flowable fill design concepts; one based on the reactor fill grout and the other based on a shrinkage compensating flowable fill mix design. 4

  4. Efficient acid-catalyzed (18) F/(19) F fluoride exchange of BODIPY dyes.

    PubMed

    Keliher, Edmund J; Klubnick, Jenna A; Reiner, Thomas; Mazitschek, Ralph; Weissleder, Ralph

    2014-07-01

    Fluorine-containing fluorochromes are important validation agents for positron emission tomography imaging compounds, as they can be readily validated in cells by fluorescence imaging. In particular, the (18) F-labeled BODIPY-FL fluorophore has emerged as an important platform, but little is known about alternative (18) F-labeling strategies or labeling on red-shifted fluorophores. In this study we explore acid-catalyzed (18) F/(19) F exchange on a range of commercially available N-hydroxysuccinimidyl ester and maleimide BODIPY fluorophores. We show this method to be a simple and efficient (18) F-labeling strategy for a diverse span of fluorescent compounds, including a BODIPY-modified PARP-1 inhibitor, and amine- and thiol-reactive BODIPY fluorophores. PMID:24596307

  5. Magnetic Resonance Detection of CD34+ Cells from Umbilical Cord Blood Using a 19F Label

    PubMed Central

    Duinhouwer, Lucia E.; van Rossum, Bernard J. M.; van Tiel, Sandra T.; van der Werf, Ramon M.; Doeswijk, Gabriela N.; Haeck, Joost C.; Rombouts, Elwin W. J. C.; ter Borg, Mariëtte N. D.; Kotek, Gyula; Braakman, Eric; Cornelissen, Jan J.; Bernsen, Monique R.

    2015-01-01

    Impaired homing and delayed recovery upon hematopoietic stem cell transplantation (HSCT) with hematopoietic stem cells (HSC) derived from umbilical cord blood (UCB) is a major problem. Tracking transplanted cells in vivo will be helpful to detect impaired homing at an early stage and allows early interventions to improve engraftment and outcome after transplantation. In this study, we show sufficient intracellular labeling of UCB-derived CD34+ cells, with 19F-containing PLGA nanoparticles which were detectable with both flow cytometry and magnetic resonance spectroscopy (MRS). In addition, labeled CD34+ cells maintain their capacity to proliferate and differentiate, which is pivotal for successful engraftment after transplantation in vivo. These results set the stage for in vivo tracking experiments, through which the homing efficiency of transplanted cells can be studied. PMID:26394043

  6. Intracellular free calcium concentration measured with /sup 19/F NMR spectroscopy in intact ferret hearts

    SciTech Connect

    Marban, E.; Kitakaze, M.; Kusuoka, H.; Porterfield, J.K.; Yue, D.T.; Chacko, V.P.

    1987-08-01

    Changes in the intracellular free Ca/sup 2 +/ concentration, (Ca/sup 2 +/)/sub i/, mediate excitation-contraction coupling in the heart and contribute to cellular injury during ischemia and reperfusion. To study these processes directly, the authors measured (Ca/sup 2 +/)/sub i/ in perfused ferret (Mustela putorius furo) hearts using /sup 19/F NMR spectroscopy to detect the 5,5'-difluoro derivative of the Ca/sup 2 +/ chelator, 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). To load cells, hearts were perfused with the acetoxymethyl ester derivative of 5,5'-F/sub 2/-BAPTA. They measured /sup 19/F NMR spectra and left ventricular pressure simultaneously,at rest and during pacing at various external Ca concentrations ((Ca)/sub 0/). Although contractile force was attenuated by the Ca/sup 2 +/ buffering properties of 5,5'-F/sup 2/-BAPTA, the decrease in pressure could be overcome by raising (Ca)/sub 0/. The mean value of 104 nM for (Ca/sup 2 +/)/sub i/ at rest in the perfused heart agrees well with previous measurements in isolated ventricular muscle. During pacing at 0.6-4 Hz, time-averaged (Ca/sup 2 +/)/sub i/ increased; the effect of pacing was augmented by increasing (Ca)/sub 0/. (Ca/sup 2 +/)/sub i/ more than tripled during 10-20 min of global ischemia, and returned toward control levels upon reperfusion. This approach promises to be particularly useful in investigating the physiology of intact hearts and the pathophysiology of alterations in the coronary circulation

  7. Measurement of the 19F(α,n) Cross Section for Nuclear Safeguards Science

    NASA Astrophysics Data System (ADS)

    Reingold, C. S.; Cizewski, J. A.; Burcher, S.; Manning, B.; Peters, W. A.; Clement, R. R. C.; Smith, M. S.; Bardayan, D. W.; Stech, E.; Tan, W. P.; Madurga, M.; Ilyushkin, S.; Thompson, S.; Vandle Collaboration

    2014-09-01

    A precise measurement of the 19F(α,n) cross section will improve Non Destructive Assays (NDA) of UF6 and other actinide-fluoride samples via neutron detection techniques. The cross section will be determined with two complementary approaches. We have already bombarded a LaF3 target with a pulsed 4He beam from the Notre Dame FN tandem accelerator; next, we will send a fluorine beam from the ORNL tandem through a pure helium gas target. The neutron spectra from both of these reactions will be measured using the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and coincident γ rays with a HPGe detector. We report here on data taken with VANDLE and a HPGe detector on a LaF3 target. This poster outlines the motivation for this experiment, explains the stages of this experiment, and presents both of our experimental setups and preliminary data. A precise measurement of the 19F(α,n) cross section will improve Non Destructive Assays (NDA) of UF6 and other actinide-fluoride samples via neutron detection techniques. The cross section will be determined with two complementary approaches. We have already bombarded a LaF3 target with a pulsed 4He beam from the Notre Dame FN tandem accelerator; next, we will send a fluorine beam from the ORNL tandem through a pure helium gas target. The neutron spectra from both of these reactions will be measured using the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and coincident γ rays with a HPGe detector. We report here on data taken with VANDLE and a HPGe detector on a LaF3 target. This poster outlines the motivation for this experiment, explains the stages of this experiment, and presents both of our experimental setups and preliminary data. This work is supported by the NNSA, NSF, and DOE.

  8. Balanced UTE-SSFP for 19F MR Imaging of Complex Spectra

    PubMed Central

    Goette, Matthew J.; Keupp, Jochen; Rahmer, Jürgen; Lanza, Gregory M.; Wickline, Samuel A.; Caruthers, Shelton D.

    2015-01-01

    Purpose A novel technique for highly sensitive detection of multi-resonant fluorine imaging agents was designed and tested with the use of dual-frequency 19F/1H ultra-short echo times (UTE) sampled with a balanced steady-state free precession (SSFP) pulse sequence and 3D radial readout. Methods Feasibility of 3D radial balanced UTE-SSFP imaging was demonstrated for a phantom comprising liquid perfluorooctyl bromide (PFOB). Sensitivity of the pulse sequence was measured and compared to other sequences imaging the PFOB (CF2)6 line group including UTE radial gradient-echo (GRE) at α=30°, as well as Cartesian GRE, balanced SSFP, and fast spin-echo (FSE). The PFOB CF3 peak was also sampled with FSE. Results The proposed balanced UTE-SSFP technique exhibited a relative detection sensitivity of 51 μmolPFOB−1min−1/2 (α=30°), at least twice that of other sequence types with either 3D radial (UTE GRE: 20 μmolPFOB−1min−1/2) or Cartesian k-space filling (GRE: 12 μmolPFOB−1min−1/2; FSE: 16 μmolPFOB−1min−1/2 balanced SSFP: 23 μmolPFOB−1min−1/2 In vivo imaging of angiogenesis-targeted PFOB nanoparticles was demonstrated in a rabbit model of cancer on a clinical 3T scanner. Conclusion A new dual 19F/1H balanced UTE-SSFP sequence manifests high SNR, with detection sensitivity more than twofold better than traditional techniques, and alleviates imaging problems caused by dephasing in complex spectra. PMID:25163853

  9. Absolute (γ,p0) and (γ,p1) cross sections and angular distributions for the light, deformed nucleus 19F

    NASA Astrophysics Data System (ADS)

    Kerkhove, E.; Ferdinande, H.; van de Vyver, R.; Berkvens, P.; van Otten, P.; van Camp, E.; Ryckbosch, D.

    1984-06-01

    Absolute (γ,p0) and (γ,p1) differential cross sections for 19F have been measured at seven angles in the energy interval between 13.4 and 25.8 MeV. A sum of Legendre polynomials was fitted to the angular distributions to deduce the angular distribution coefficients. The (γ,p0) and (γ,p1) cross sections have a similar magnitude and represent a minor fraction of the total photoproton channel. The global difference between the two cross sections is attributed to configurational splitting effects. From the (γ,p0) angular distribution coefficients, an E2 cross section was estimated, contributing about 37% to the total E2 energy-weighted sum rule.

  10. Binding energies and 19F nuclear magnetic deshielding in paramagnetic halogen-bonded complexes of TEMPO with haloperfluorocarbons.

    PubMed

    Cavallotti, Carlo; Metrangolo, Pierangelo; Meyer, Franck; Recupero, Francesco; Resnati, Giuseppe

    2008-10-01

    19F NMR measurements and theoretical calculations were performed to study paramagnetic complexes of iodoperfluorocarbons with stable nitroxide radicals. Contrary to what is usually measured for diamagnetic halogen-bonded complexes involving iodoperfluorocarbons, it was found that the formation of complexes with the 2,2,6,6-tetramethyl(piperidin-1-yloxyl) (TEMPO) radical determines downfield shifts in the 19F NMR spectra. The experimental finding was confirmed by calculating nuclear shielding using density functional theory and correcting the isotropic diamagnetic (19)F chemical shift with contact interactions evaluated from the hyperfine coupling tensor. The computational analysis of the interaction between CF3I and TEMPO, by using DFT and MP2 theories, showed that the occurrence of the halogen bond between the interacting partners is associated with a significant charge transfer to CF3I and that the measured downfield shift is due to the occurring spin transfer. PMID:18795762

  11. Visualizing brain inflammation with a shingled-leg radio-frequency head probe for 19F/1H MRI.

    PubMed

    Waiczies, Helmar; Lepore, Stefano; Drechsler, Susanne; Qadri, Fatimunnisa; Purfürst, Bettina; Sydow, Karl; Dathe, Margitta; Kühne, André; Lindel, Tomasz; Hoffmann, Werner; Pohlmann, Andreas; Niendorf, Thoralf; Waiczies, Sonia

    2013-01-01

    Magnetic resonance imaging (MRI) provides the opportunity of tracking cells in vivo. Major challenges in dissecting cells from the recipient tissue and signal sensitivity constraints albeit exist. In this study, we aimed to tackle these limitations in order to study inflammation in autoimmune encephalomyelitis. We constructed a very small dual-tunable radio frequency (RF) birdcage probe tailored for (19)F (fluorine) and (1)H (proton) MR mouse neuroimaging. The novel design eliminated the need for extra electrical components on the probe structure and afforded a uniform -field as well as good SNR. We employed fluorescently-tagged (19)F nanoparticles and could study the dynamics of inflammatory cells between CNS and lymphatic system during development of encephalomyelitis, even within regions of the brain that are otherwise not easily visualized by conventional probes. (19)F/(1)H MR Neuroimaging will allow us to study the nature of immune cell infiltration during brain inflammation over an extensive period of time. PMID:23412352

  12. TANKS 18 AND 19-F STRUCTURAL FLOWABLE GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS

    SciTech Connect

    Stefanko, D.; Langton, C.

    2011-11-01

    Cementitious grout will be used to close Tanks 18-F and 19-F. The functions of the grout are to: (1) physically stabilize the final landfill by filling the empty volume in the tanks with a non compressible material; (2) provide a barrier for inadvertent intrusion into the tank; (3) reduce contaminant mobility by (a) limiting the hydraulic conductivity of the closed tank and (b) reducing contact between the residual waste and infiltrating water; and (4) providing an alkaline, chemically reducing environment in the closed tank to control speciation and solubility of selected radionuclides. The objective of this work was to identify a single (all-in-one) grout to stabilize and isolate the residual radionuclides in the tank, provide structural stability of the closed tank and serve as an inadvertent intruder barrier. This work was requested by V. A. Chander, High Level Waste (HLW) Tank Engineering, in HLW-TTR-2011-008. The complete task scope is provided in the Task Technical and QA Plan, SRNL-RP-2011-00587 Revision 0. The specific objectives of this task were to: (1) Identify new admixtures and dosages for formulating a zero bleed flowable tank fill material selected by HLW Tank Closure Project personnel based on earlier tank fill studies performed in 2007. The chemical admixtures used for adjusting the flow properties needed to be updated because the original admixture products are no longer available. Also, the sources of cement and fly ash have changed, and Portland cements currently available contain up to 5 wt. % limestone (calcium carbonate). (2) Prepare and evaluate the placement, compressive strength, and thermal properties of the selected formulation with new admixture dosages. (3) Identify opportunities for improving the mix selected by HLW Closure Project personnel and prepare and evaluate two potentially improved zero bleed flowable fill design concepts; one based on the reactor fill grout and the other based on a shrinkage compensating flowable fill mix

  13. Using magnetic coupling to implement 1H, 19F, 13C experiments in routine high resolution NMR probes

    NASA Astrophysics Data System (ADS)

    Bowyer, Paul; Finnigan, Jim; Marsden, Brian; Taber, Bob; Zens, Albert

    2015-12-01

    We report in this paper the design of 1H, 19F, 13C circuitry using magnetic coupling which can do on demand experiments where one of the three nuclei is observed and the other two are decoupled. The implementation of this circuitry in routine NMR probes is compared with capacitive coupling methods where it was found that by using magnetic coupling the performance of the routine NMR probe was not impacted by the addition of this circuitry. It is surmised that using this type of circuitry would be highly desirable for those chemists doing routine 19F NMR.

  14. Binary channels of the {sup 19}F-on-{sup 12}C reaction at 92 MeV

    SciTech Connect

    Aissaoui, N.; Haas, F.; Freeman, R.M.; Beck, C.; Morsad, A.; Djerroud, B.; Caplar, R.; Hachem, A.

    1997-01-01

    Binary-reaction channels of {sup 19}F+{sup 12}C have been studied at E{sub lab}({sup 19}F)=92 MeV using kinematic coincidence techniques. The results are discussed in the light of previous inclusive measurements performed at the same incident energy and for which the occurrence of an important incomplete fusion mechanism after projectile breakup was proposed. Evidence for strong damped binary, especially quasisymmetric, decay processes is found. {copyright} {ital 1997} {ital The American Physical Society}

  15. An overview of the 19F(p,α0)16 O reaction with direct methods

    NASA Astrophysics Data System (ADS)

    Dell’Aquila, D.; Lombardo, I.

    2016-04-01

    The study of the 19F(p,α)16O reaction at low energy is important both for Nuclear Structure and Astrophysics. Despite of its importance, the S-factor of this reaction is poorly known, especially at astrophysical energies. We present an overview of the 19F(p,α0)16O reaction cross section, as obtained from recent direct measurements and from published works in the literature. We include in the systematic also data from an unpublished work, where several excitation functions and angular distributions for α0 and απ channels are reported.

  16. Science meets magic: photonic metamaterials

    NASA Astrophysics Data System (ADS)

    Ozbay, Ekmel

    2012-05-01

    The word "magic" is usually associated with movies, fiction, children stories, etc. but seldom with the natural sciences. Recent advances in metamaterials have changed this notion, in which we can now speak of "almost magical" properties that scientists could only dream about only a decade ago. In this article, we review some of the recent "almost magical" progress in the field of meta-materials.

  17. Science meets magic: photonic metamaterials

    NASA Astrophysics Data System (ADS)

    Ozbay, Ekmel

    2012-03-01

    The word "magic" is usually associated with movies, fiction, children stories, etc. but seldom with the natural sciences. Recent advances in metamaterials have changed this notion, in which we can now speak of "almost magical" properties that scientists could only dream about only a decade ago. In this article, we review some of the recent "almost magical" progress in the field of meta-materials.

  18. Blazar Observations with the MAGIC Telescope

    NASA Astrophysics Data System (ADS)

    Kneiske, T. M.; Mannheim, K.

    The MAGIC Telescope will be able to detect gamma gay sources down to energies of 30GeV. Therefore a large number of sources will be seen, especially blazars. 30 GeV is also the upper energy limit of EGRET. Therefore it is possible to extrapolate a spectrum of an EGRET source without a complicated model. We make first predictions about the detectability of EGRET blazars calculating the minimum observation time for the MAGIC Telescope. Blazars are often located at high redshifts and their spectra should show some cut-offs at high energies due to pair production processes with low energy background photons. We developed a background radiation model using recent results of optical to infrared data and included this absorption effect in our calculation about the observability. We found that the shape of the spectrum and the intergalactic absorption does not make a big difference for a simple detection of the source. The observation time is only dependent on the flux near the energy threshold of the telescope (30 GeV) and the zenith angle of the blazar. The results are showing that MAGIC will be able to detect more than 50% of the EGRET sources even at high redshift and therefore it will be a good tool for multi-wavelength campaigns.

  19. 19F-NMR reveals metal and operator-induced allostery in MerR.

    PubMed

    Song, Lingyun; Teng, Quincy; Phillips, Robert S; Brewer, John M; Summers, Anne O

    2007-08-01

    Metalloregulators of the MerR family activate transcription upon metal binding by underwinding the operator-promoter DNA to permit open complex formation by pre-bound RNA polymerase. Historically, MerR's allostery has been monitored only indirectly via nuclease sensitivity or by fluorescent nucleotide probes and was very specific for Hg(II), although purified MerR binds several thiophilic metals. To observe directly MerR's ligand-induced behavior we made 2-fluorotyrosine-substituted MerR and found similar, minor changes in (19)F chemical shifts of tyrosine residues in the free protein exposed to Hg(II), Cd(II) or Zn(II). However, DNA binding elicits large chemical shift changes in MerR's tyrosine residues and in DNA-bound MerR Hg(II) provokes changes very distinct from those of Cd(II) or Zn(II). These chemical shift changes and other biophysical and phenotypic properties of wild-type MerR and relevant mutants reveal elements of an allosteric network that enables the coordination state of the metal binding site to direct metal-specific movements in the distant DNA binding site and the DNA-bound state also to affect the metal binding domain. PMID:17560604

  20. Constraints on low-mass WIMP interactions on 19F from PICASSO

    NASA Astrophysics Data System (ADS)

    Archambault, S.; Behnke, E.; Bhattacharjee, P.; Bhattacharya, S.; Dai, X.; Das, M.; Davour, A.; Debris, F.; Dhungana, N.; Farine, J.; Gagnebin, S.; Giroux, G.; Grace, E.; Jackson, C. M.; Kamaha, A.; Krauss, C.; Kumaratunga, S.; Lafrenière, M.; Laurin, M.; Lawson, I.; Lessard, L.; Levine, I.; Levy, C.; MacDonald, R. P.; Marlisov, D.; Martin, J.-P.; Mitra, P.; Noble, A. J.; Piro, M.-C.; Podviyanuk, R.; Pospisil, S.; Saha, S.; Scallon, O.; Seth, S.; Starinski, N.; Stekl, I.; Wichoski, U.; Xie, T.; Zacek, V.

    2012-05-01

    Recent results from the PICASSO dark matter search experiment at SNOLAB are reported. These results were obtained using a subset of 10 detectors with a total target mass of 0.72 kg of 19F and an exposure of 114 kgd. The low backgrounds in PICASSO allow recoil energy thresholds as low as 1.7 keV to be obtained which results in an increased sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c2. No dark matter signal was found. Best exclusion limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c2 with a cross section on protons of σpSD=0.032 pb (90% C.L.). In the spin independent sector close to the low mass region of 7 GeV/c2 favoured by CoGeNT and DAMA/LIBRA, cross sections larger than σpSI=1.41×10-4 pb (90% C.L.) are excluded.

  1. (19)F(α,n) thick target yield from 3.5 to 10.0 MeV.

    PubMed

    Norman, E B; Chupp, T E; Lesko, K T; Grant, P J; Woodruff, G L

    2015-09-01

    Using a target of PbF2, the thick-target yield from the (19)F(α,n) reaction was measured from E(α)=3.5-10 MeV. From these results, we infer the thick-target neutron yields from targets of F2 and UF6 over this same alpha-particle energy range. PMID:26115205

  2. Fluorinated Carbohydrates as Lectin Ligands: 19F-Based Direct STD Monitoring for Detection of Anomeric Selectivity

    PubMed Central

    Ribeiro, João P.; Diercks, Tammo; Jiménez-Barbero, Jesús; André, Sabine; Gabius, Hans-Joachim; Cañada, Francisco Javier

    2015-01-01

    The characterization of the binding of reducing carbohydrates present as mixtures of anomers in solution to a sugar recepor (lectin) poses severe difficulties. In this situation, NMR spectroscopy enables the observation of signals for each anomer in the mixture by applying approaches based on ligand observation. Saturation transfer difference (STD) NMR allows fast and efficient screening of compound mixtures for reactivity to a receptor. Owing to the exceptionally favorable properties of 19F in NMR spectroscopy and the often complex 1H spectra of carbohydrates, 19F-containing sugars have the potential to be turned into versatile sensors for recognition. Extending the recently established 1H → 1H STDre19F-NMR technique, we here demonstrate its applicability to measure anomeric selectivity of binding in a model system using the plant lectin concanavalin A (ConA) and 2-deoxy-2-fluoro-d-mannose. Indeed, it is also possible to account for the mutual inhibition between the anomers on binding to the lectin by means of a kinetic model. The monitoring of 19F-NMR signal perturbation disclosed the relative activities of the anomers in solution and thus enabled the calculation of their binding affinity towards ConA. The obtained data show a preference for the α anomer that increases with temperature. This experimental approach can be extended to others systems of biomedical interest by testing human lectins with suitably tailored glycan derivatives. PMID:26580665

  3. Mapping phosphorylation rate of fluoro-deoxy-glucose in rat brain by 19F chemical shift imaging

    PubMed Central

    Coman, Daniel; Sanganahalli, Basavaraju G.; Cheng, David; McCarthy, Timothy; Rothman, Douglas L.; Hyder, Fahmeed

    2014-01-01

    19F magnetic resonance spectroscopy (MRS) studies of 2-fluoro-2-deoxy-D-glucose (FDG) and 2-fluoro-2-deoxy-D-glucose-6-phosphate (FDG-6P) can be used for directly assessing total glucose metabolism in vivo. To date, 19F MRS measurements of FDG phosphorylation in the brain have either been achieved ex vivo from extracted tissue or in vivo by unusually long acquisition times. Electrophysiological and functional magnetic resonance imaging (fMRI) measurements indicate that FDG doses up to 500mg/kg can be tolerated with minimal side effects on cerebral physiology and evoked fMRI-BOLD responses to forepaw stimulation. In halothane-anesthetized rats, we report localized in vivo detection and separation of FDG and FDG-6P MRS signals with 19F 2D chemical shift imaging (CSI) at 11.7T. A metabolic model based on reversible transport between plasma and brain tissue, which included a non-saturable plasma to tissue component, was used to calculate spatial distribution of FDG and FDG-6P concentrations in rat brain. In addition, spatial distribution of rate constants and metabolic fluxes of FDG to FDG-6P conversion were estimated. Mapping the rate of FDG to FDG-6P conversion by 19F CSI provides an MR methodology that could impact other in vivo applications such as characterization of tumor pathophysiology. PMID:24581725

  4. Energy dependence of fission fragment angular distributions for 19F, 24Mg and 28Si induced reactions on 208Pb

    NASA Astrophysics Data System (ADS)

    Tsang, M. B.; Utsunomiya, H.; Gelbke, C. K.; Lynch, W. G.; Back, B. B.; Saini, S.; Baisden, P. A.; McMahan, M. A.

    1983-09-01

    The energy dependence of fission fragment angular distributions was measured for reaction induced by 19F, 24Mg, and 28Si on 208Pb over the range of incident energies of {E}/{A} = 5.6-10 MeV. For all three systems the angular distributions are inconsistent with the saddle point deformations of the rotating liquid drop model.

  5. Angular Distribution and Angular Dispersion in Collision of 19F+27Al at 114 MeV

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Dong, Yu-Chuan; Li, Song-Lin; Duan, Li-Min; Xu, Hu-Shan; Xu, Hua-Gen; Chen, Ruo-Fu; Wu, He-Yu; Han, Jian-Long; Li, Zhi-Chang; Lu, Xiu-Qin; Zhao, Kui; Liu, Jian-Cheng; Sergey, Yu-Kun

    2004-10-01

    Angular distributions of fragments B, C, N, O, F, Ne, Na, Mg and Al induced by the collision of 19F+27Al at 114 MeV have been measured. Angular dispersion parameters are extracted from the experimental data and compared with the theoretical ones. The dynamic dispersions for dissipative products depend strongly on the charge number Z of the fragments.

  6. Technical advance: monitoring the trafficking of neutrophil granulocytes and monocytes during the course of tissue inflammation by noninvasive 19F MRI.

    PubMed

    Temme, Sebastian; Jacoby, Christoph; Ding, Zhaoping; Bönner, Florian; Borg, Nadine; Schrader, Jürgen; Flögel, Ulrich

    2014-04-01

    Inflammation results in the recruitment of neutrophils and monocytes, which is crucial for the healing process. In the present study, we used (19)F MRI to monitor in vivo the infiltration of neutrophils and monocytes from the onset of inflammation to the resolution and healing phase. Matrigel, with or without LPS, was s.c.-implanted into C57BL/6 mice. This resulted in a focal inflammation lasting over a period of 20 days, with constantly decreasing LPS levels in doped matrigel plugs. After i.v. administration of (19)F containing contrast agent, (19)F MRI revealed a zonular (19)F signal in the periphery of LPS containing matrigel plugs, which was not observed in control plugs. Analysis of the (19)F signal over the observation period demonstrated the strongest (19)F signal after 24 h, which decreased to nearly zero after 20 days. The (19)F signal was mirrored by the amount of leukocytes in the matrigel, with neutrophils dominating at early time-points and macrophages at later time-points. Both populations were shown to take up the (19)F contrast agent. In conclusion, (19)F MRI, in combination with the matrigel/LPS model, permits the noninvasive analysis of neutrophil and monocyte infiltration over the complete course of inflammation in vivo. PMID:24319285

  7. Impact of Zeolite Transferred from Tank 19F to Tank 18F on DWPF Vitrification of Sludge Batch 3

    SciTech Connect

    Jantzen, C.M.

    2004-01-07

    The Defense Waste Processing Facility (DWPF) is planning to initiate vitrification of Sludge Batch 3 (SB3) in combination with Sludge Batch 2 (SB2) in the spring of 2004. The contents of Sludge Batch 3 will be a mixture of the heel remaining from Sludge Batch 1B, sludge from Tank 7F (containing coal, sand, and sodium oxalate), and sludge materials from Tank 18F. The sludge materials in Tank 18F contain part of a mound of zeolitic material transferred there from Tank 19F. This mound was physically broken up and transfers were made from Tank 19F to Tank 18F for vitrification into SB3. In addition, excess Pu and Am/Cm materials were transferred to Tank 51H to be processed through the DWPF as part of SB3. Additional Pu material and a Np stream from the Canyons are also planned to be added to SB3 before processing of this batch commences at DWPF. The primary objective of this task was to assess the impacts of the excess zeolite mound material in Tank 19F on the predicted glass and processing properties of interest when the zeolite becomes part of SB3. The two potential impacts of the Tank 19F zeolite mound on DWPF processing relates to (1) the samples taken for determination of the acceptability of a macrobatch of DWPF feed and (2) the achievable waste loading. The potential effects of the large size of the zeolite particles found in the Tank 19F solids, as reported in this study, are considered minimal for processing of SB3 in DWPF. Other findings about the zeolite conversion mechanism via a process of Ostwald ripening are discussed in the text and in the conclusions.

  8. (19)F-labeling of the adenine H2-site to study large RNAs by NMR spectroscopy.

    PubMed

    Sochor, F; Silvers, R; Müller, D; Richter, C; Fürtig, B; Schwalbe, H

    2016-01-01

    In comparison to proteins and protein complexes, the size of RNA amenable to NMR studies is limited despite the development of new isotopic labeling strategies including deuteration and ligation of differentially labeled RNAs. Due to the restricted chemical shift dispersion in only four different nucleotides spectral resolution remains limited in larger RNAs. Labeling RNAs with the NMR-active nucleus (19)F has previously been introduced for small RNAs up to 40 nucleotides (nt). In the presented work, we study the natural occurring RNA aptamer domain of the guanine-sensing riboswitch comprising 73 nucleotides from Bacillus subtilis. The work includes protocols for improved in vitro transcription of 2-fluoroadenosine-5'-triphosphat (2F-ATP) using the mutant P266L of the T7 RNA polymerase. Our NMR analysis shows that the secondary and tertiary structure of the riboswitch is fully maintained and that the specific binding of the cognate ligand hypoxanthine is not impaired by the introduction of the (19)F isotope. The thermal stability of the (19)F-labeled riboswitch is not altered compared to the unmodified sequence, but local base pair stabilities, as measured by hydrogen exchange experiments, are modulated. The characteristic change in the chemical shift of the imino resonances detected in a (1)H,(15)N-HSQC allow the identification of Watson-Crick base paired uridine signals and the (19)F resonances can be used as reporters for tertiary and secondary structure transitions, confirming the potential of (19)F-labeling even for sizeable RNAs in the range of 70 nucleotides. PMID:26704707

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

    NASA Astrophysics Data System (ADS)

    Urbanova, Martina; Brus, Jiri; Sedenkova, Ivana; Policianova, Olivia; Kobera, Libor

    In this contribution the ability of 19F MAS NMR spectroscopy to probe structural variability of poorly water-soluble drugs formulated as solid dispersions in polymer matrices is discussed. The application potentiality of the proposed approach is demonstrated on a moderately sized active pharmaceutical ingredient (API, Atorvastatin) exhibiting extensive polymorphism. In this respect, a range of model systems with the API incorporated in the matrix of polvinylpyrrolidone (PVP) was prepared. The extent of mixing of both components was determined by T1(1H) and T1ρ(1H) relaxation experiments, and it was found that the API forms nanosized domains. Subsequently it was found out that the polymer matrix induces two kinds of changes in 19F MAS NMR spectra. At first, this is a high-frequency shift reaching 2-3 ppm which is independent on molecular structure of the API and which results from the long-range polarization of the electron cloud around 19F nucleus induced by electrostatic fields of the polymer matrix. At second, this is broadening of the signals and formation of shoulders reflecting changes in molecular arrangement of the API. To avoid misleading in the interpretation of the recorded 19F MAS NMR spectra, because both the contributions act simultaneously, we applied chemometric approach based on multivariate analysis. It is demonstrated that factor analysis of the recorded spectra can separate both these spectral contributions, and the subtle structural differences in the molecular arrangement of the API in the nanosized domains can be traced. In this way 19F MAS NMR spectra of both pure APIs and APIs in solid dispersions can be directly compared. The proposed strategy thus provides a powerful tool for the analysis of new formulations of fluorinated pharmaceutical substances in polymer matrices.

  10. Magical Landscapes: Two Love Stories.

    ERIC Educational Resources Information Center

    Moore, John Noell

    2002-01-01

    Introduces two books about magic, one a collection of essays "Ex Libris: Confessions of a Common Reader," which describes the author's inherited lifelong passion for books and reading; and the other a novel, "Mangos, Bananas and Coconuts: A Cuban Love Story," which tells a story of love and magic that seems both real and surreal. (SG)

  11. Garden Gnomes: Magical or Tacky?

    ERIC Educational Resources Information Center

    Flynt, Deborah

    2012-01-01

    Garden gnomes: magical or tacky? Well, art is in the eye of the beholder, and for the author's advanced seventh-grade art class, garden gnomes are magical. Gnomes have a very long history, dating back to medieval times. A fairytale describes them as brownie-like creatures that are nocturnal helpers. In this article, the author describes how her…

  12. Old and New Magic Numbers

    SciTech Connect

    Talmi, Igal

    2008-11-11

    The discovery of magic numbers led to the shell model. They indicated closure of major shells and are robust: proton magic numbers are rather independent of the occupation of neutron orbits and vice versa. Recently the magic property became less stringent and we hear a lot about the discovery of new magic numbers. These, however, indicate sub-shell closures and strongly depend on occupation numbers and hence, may be called quasi-magic numbers. Some of these have been known for many years and the mechanism for their appearance as well as disappearance, was well understood within the simple shell model. The situation will be illustrated by a few examples which demonstrate the simple features of the shell model. Will this simplicity emerge from the complex computations of nuclear many-body theory?.

  13. "Magic" Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  14. Magical ideation and hyperacusis.

    PubMed

    Dubal, Stéphanie; Viaud-Delmon, Isabelle

    2008-01-01

    The subjective experience conferred by auditory perception has rarely been addressed outside of the studies of auditory hallucinations. The aim of this study is to describe the phenomenology of auditory experiences in individuals who endorse magical beliefs, but do not report hallucinations. We examined the relationship between subjective auditory sensitivity and a 'psychotic-like' thinking style. Hyperacusis questionnaire scores were compared between 25 high scoring participants on Chapman's magical ideation (MI) scale, 25 high scoring participants on Chapman's physical anhedonia scale and 25 control participants, pre-selected from a large student pool (n=1289). The participants who obtained high scores on the MI scale rated their auditory sensitivity higher than the two other groups. Our results indicate that, in healthy subjects, subjective auditory sensitivity is associated with MI without the mediation by anxiety commonly observed in pathological cases. We propose that hyperacusis associated to high scores of MI may be a predispositional factor to deviant auditory experiences. The relative uncoupling of perception from auditory sensory input may result in a central hypersensitivity, which could play a role in triggering off the experience of auditory hallucinations. PMID:18640670

  15. Characterization of the Tank 19F Closure Grab and Core Samples and the Tank 18F Dip Sample

    SciTech Connect

    Swingle, R.F.

    2002-05-02

    The results of analyses of the Tank 19F closure characterization samples are included herein. The samples analyzed include the two Tank 19F grab samples (FTF-075 and FTF-077) and a Tank 18F dip sample (FTF-076) taken in September 2001 and a Tank 19F core sample (FTF-118) taken in December 2001. The FTF-075 and FTF-077 grab samples were pulled from Tank 19F and the FTF-076 dip sample was pulled from Tank 18F in September 2001 as part of the characterization process for closure of Tank 19F. The samples were delivered to the Savannah River Technology Center (SRTC) Shielded Cells on September 28, 2001 and placed in the Shielded Cells on October 2, 2001. The samples were opened and both grab samples were found to contain plenty of material to allow completion of the analyses. The samples were dark and resembled marsh muck (see Figures 1 and 2). The dip sample was also found to contain plenty of material. The sample looked like muddy water (Figure 4). The FTF-118F core sample was pulled from Tank 19F in December 2001 as part of the characterization process for closure of the tank. The sample was delivered to the SRTC Shielded Cells on December 6, 2001 and placed in the Shielded Cells on December 7, 2001. The sample was opened and found to contain plenty of material to allow completion of the analyses. As evident in Figure 3, the sample resembled a somewhat drier version of the previous grab samples FTF-075 and FTF-077. A group consisting of SRTC Waste Processing Technology (WPT) section personnel and High Level Waste Engineering (HLWE) personnel viewed the sample when it was opened and came to the consensus that the sample appeared to be homogeneous. The decision was made to treat the sample as a single phase and analyze accordingly. Initially, small portions were archived from the top, middle and bottom of the sample in case it is later decided to analyze the levels of the sample separately. The analytical results from the two grab samples and the core sample were all

  16. Fluorinated Amino-Derivatives of the Sesquiterpene Lactone, Parthenolide, as 19F NMR Probes in Deuterium-Free Environments

    PubMed Central

    Woods, James R.; Mo, Huaping; Bieberich, Andrew A.; Alavanja, Tanja; Colby, David A.

    2011-01-01

    The design, synthesis, and biological activity of fluorinated amino-derivatives of the sesquiterpene lactone, parthenolide, are described. A fluorinated aminoparthenolide analogue with biological activity similar to the parent natural product was discovered, and its X-ray structure was obtained. This lead compound was then studied using 19F NMR in the presence and absence of glutathione to obtain additional mechanism of action data, and it was found that the aminoparthenolide eliminates amine faster in the presence of glutathione than in the absence of glutathione. The exact changes in concentrations of fluorinated compound and amine were quantified by a concentration-reference method using 19F NMR; a major benefit of applying this strategy is that no deuterated solvents or internal standards are required to obtain accurate concentrations. These mechanistic data with glutathione may contribute to the conversion of the amino-derivative to parthenolide, the active pharmacological agent, in glutathione-rich cancer cells. PMID:22029741

  17. Parahydrogen-induced polarization transfer to 19F in perfluorocarbons for 19F NMR spectroscopy and MRI.

    PubMed

    Plaumann, Markus; Bommerich, Ute; Trantzschel, Thomas; Lego, Denise; Dillenberger, Sonja; Sauer, Grit; Bargon, Joachim; Buntkowsky, Gerd; Bernarding, Johannes

    2013-05-10

    Fluorinated substances are important in chemistry, industry, and the life sciences. In a new approach, parahydrogen-induced polarization (PHIP) is applied to enhance (19)F MR signals of (perfluoro-n-hexyl)ethene and (perfluoro-n-hexyl)ethane. Unexpectedly, the end-standing CF3 group exhibits the highest amount of polarization despite the negligible coupling to the added protons. To clarify this non-intuitive distribution of polarization, signal enhancements in deuterated chloroform and acetone were compared and (19)F-(19)F NOESY spectra, as well as (19)F T1 values were measured by NMR spectroscopy. By using the well separated and enhanced signal of the CF3 group, first (19)F MR images of hyperpolarized linear semifluorinated alkenes were recorded. PMID:23526596

  18. Probing different perfluorocarbons for in vivo inflammation imaging by 19F MRI: image reconstruction, biological half-lives and sensitivity.

    PubMed

    Jacoby, Christoph; Temme, Sebastian; Mayenfels, Friederike; Benoit, Nicole; Krafft, Marie Pierre; Schubert, Rolf; Schrader, Jürgen; Flögel, Ulrich

    2014-03-01

    Inflammatory processes can reliably be assessed by (19)F MRI using perfluorocarbons (PFCs), which is primarily based on the efficient uptake of emulsified PFCs by circulating cells of the monocyte-macrophage system and subsequent infiltration of the (19)F-labeled cells into affected tissue. An ideal candidate for the sensitive detection of fluorine-loaded cells is the biochemically inert perfluoro-15-crown-5 ether (PFCE), as it contains 20 magnetically equivalent (19)F atoms. However, the biological half-life of PFCE in the liver and spleen is extremely long, and so this substance is not suitable for future clinical applications. In the present study, we investigated alternative, nontoxic PFCs with predicted short biological half-lives and high fluorine content: perfluorooctyl bromide (PFOB), perfluorodecalin (PFD) and trans-bis-perfluorobutyl ethylene (F-44E). Despite the complex spectra of these compounds, we obtained artifact-free images using sine-squared acquisition-weighted three-dimensional chemical shift imaging and dedicated reconstruction accomplished with in-house-developed software. The signal-to-noise ratio of the images was maximized using a Nutall window with only moderate localization error. Using this approach, the retention times of the different PFCs in murine liver and spleen were determined at 9.4 T. The biological half-lives were estimated to be 9 days (PFD), 12 days (PFOB) and 28 days (F-44E), compared with more than 250 days for PFCE. In vivo sensitivity for inflammation imaging was assessed using an ear clip injury model. The alternative PFCs PFOB and F-44E provided 37% and 43%, respectively, of the PFCE intensities, whereas PFD did not show any signal in the ear model. Thus, for in vivo monitoring of inflammatory processes, PFOB emerges as the most promising candidate for possible future translation of (19)F MR inflammation imaging to human applications. PMID:24353148

  19. Novel 19F Activatable Probe for the Detection of Matrix Metalloprotease-2 Activity by MRI/MRS

    PubMed Central

    2015-01-01

    Matrix metalloproteases (MMPs) have been found to be highly expressed in a variety of malignant tumor tissues. Noninvasive visualization of MMP activity may play an important role in the diagnosis of MMP associated diseases. Here we report the design and synthesis of a set of fluorine-19 dendron-based magnetic resonance imaging (MRI) probes for real-time imaging of MMP-2 activity. The probes have the following features: (a) symmetrical fluorine atoms; (b) the number of fluorine atoms can be increased through facile chemical modification; (c) readily accessible peptide sequence as the MMP-2 substrate; (d) activatable 19F signal (off/on mode) via paramagnetic metal ion incorporation. Following optimization for water solubility, one of the probes was selected to evaluate MMP-2 activity by 19F magnetic resonance spectroscopy (MRS). Our results showed that the fluorine signal increased by 8.5-fold in the presence of MMP-2. The specific cleavage site was verified by mass spectrometry. The selected probe was further applied to detect secreted MMP-2 activity of living SCC7 squamous cell carcinoma cells. The fluorine signal was increased by 4.8-fold by MRS analysis after 24 h incubation with SCC7 cells. This type of fluorine probe can be applied to evaluate other enzyme activities by simply tuning the substrate structures. This symmetrical fluorine dendron-based probe design extends the scope of the existing 19F MRI agents and provides a simple but robust method for real-time 19F MRI application. PMID:25271556

  20. NMR spectroscopy in studies of light-induced structural changes in mammalian rhodopsin: applicability of solution (19)F NMR.

    PubMed

    Klein-Seetharaman, J; Getmanova, E V; Loewen, M C; Reeves, P J; Khorana, H G

    1999-11-23

    We report high resolution solution (19)F NMR spectra of fluorine-labeled rhodopsin mutants in detergent micelles. Single cysteine substitution mutants in the cytoplasmic face of rhodopsin were labeled by attachment of the trifluoroethylthio (TET), CF(3)-CH(2)-S, group through a disulfide linkage. TET-labeled cysteine mutants at amino acid positions 67, 140, 245, 248, 311, and 316 in rhodopsin were thus prepared. Purified mutant rhodopsins (6-10 mg), in dodecylmaltoside, were analyzed at 20 degrees C by solution (19)F NMR spectroscopy. The spectra recorded in the dark showed the following chemical shifts relative to trifluoroacetate: Cys-67, 9.8 ppm; Cys-140, 10.6 ppm; Cys-245, 9.9 ppm; Cys-248, 9.5 ppm; Cys-311, 9.9 ppm; and Cys-316, 10.0 ppm. Thus, all mutants showed chemical shifts downfield that of free TET (6.5 ppm). On illumination to form metarhodopsin II, upfield changes in chemical shift were observed for (19)F labels at positions 67 (-0.2 ppm) and 140 (-0.4 ppm) and downfield changes for positions 248 (+0.1 ppm) and 316 (+0.1 ppm) whereas little or no change was observed at positions 311 and 245. On decay of metarhodopsin II, the chemical shifts reverted largely to those originally observed in the dark. The results demonstrate the applicability of solution (19)F NMR spectroscopy to studies of the tertiary structures in the cytoplasmic face of intact rhodopsin in the dark and on light activation. PMID:10570143

  1. Conformation of gramicidin A channel in phospholipid vesicles: a 13C and 19F nuclear magnetic resonance study.

    PubMed Central

    Weinstein, S; Wallace, B A; Blout, E R; Morrow, J S; Veatch, W

    1979-01-01

    We have determined the conformation of the channel-forming polypeptide antibiotic gramicidin A in phosphatidylcholine vesicles by using 13C and 19F NMR spectroscopy. The models previously proposed for the conformation of the dimer channel differ in the surface localization of the NH2 and COOH termini. We have incorporated specific 13C and 19F nuclei at both the NH2, and COOH termini of gramicidin and have used 13C and 19F chemical shifts and spin lattice relaxation time measurements to determine the accessibility of these labels to three paramagnetic NMR probes--two in aqueous solution and one attached to the phosphatidylcholine fatty acid chain9 all of our results indicate that the COOH terminus of gramicidin in the channel is located near the surface of the membrane and the NH2 terminus is buried deep within the lipid bilayer. These findings strongly favor an NH2-terminal to NH2-terminal helical dimer as the major conformation for the gramicidin channel in phosphatidylcholine vesicles. PMID:92025

  2. Dual 19F/1H MR gene reporter molecules for in vivo detection of β-galactosidase

    PubMed Central

    Yu, Jian-Xin; Kodibagkar, Vikram D.; Hallac, Rami R.; Liu, Li; Mason, Ralph P.

    2012-01-01

    Increased emphasis on personalized medicine and novel therapies require the development of non-invasive strategies for assessing biochemistry in vivo. The detection of enzyme activity and gene expression in vivo is potentially important for the characterization of diseases and gene therapy. Magnetic resonance imaging (MRI) is a particularly promising tool since it is non-invasive, and has no associated radioactivity, yet penetrates deep tissue. We now demonstrate a novel class of dual 1H/19F nuclear magnetic resonance (NMR) lacZ gene reporter molecule to specifically reveal enzyme activity in human tumor xenografts growing in mice. We report the design, synthesis, and characterization of six novel molecules and evaluation of the most effective reporter in mice in vivo. Substrates show a single 19F NMR signal and exposure to β-galactosidase induces a large 19F NMR chemical shift response. In the presence of ferric ions the liberated aglycone generates intense proton MRI T2 contrast. The dual modality approach allows both the detection of substrate and imaging of product enhancing the confidence in enzyme detection. PMID:22352428

  3. Identification of 2-Fluoro-2-deoxy- D-glucose Metabolites by 19F{ 1H} Hetero-RELAY

    NASA Astrophysics Data System (ADS)

    O'Connell, Thomas M.; London, Robert E.

    1995-12-01

    It has been proposed that in mammalian systems the glucose analog 2-fluoro-2-deoxy-D-glucose (FDG) is phosphoryated and subsequently converted to the corresponding mannose derivative via the action of phosphoglucose isomerase. As is generally true in metabolic studies of fluorinated molecules, the fluorine spectrum alone is suggestive, without providing definitive structural evidence, while the use of1H NMR techniques generally suffers from a lack of adequate selectivity. A1H-19F version of the hetero-RELAY experiment has been applied to this problem. Formation of the corresponding C-6 phosphorylated 2-FDG analog with hexokinase, followed by treatment of the resulting phosphorylated products with phosphoglucose isomerase, resulted in the observation of additional19F resonances consistent with the corresponding 2-fluoro-2-deoxy-D-mannose-6-phosphate metabolite. A more definitive product identification was obtained using the hetero-RELAY experiment, which provides a complete19F-decoupled proton spectrum for each of the fluorinated species.

  4. Multimodal Perfluorocarbon Nanoemulsions for 19F MRI, Ultrasonography, and Catalysis of MRgFUS-Mediated Drug Delivery

    NASA Astrophysics Data System (ADS)

    Rapoport, N.; Nam, K.-H.; Christensen, D. A.; Kennedy, A. M.; Parker, D. L.; Payne, A. H.; Todd, N.; Shea, J. E.; Scaife, C. L.

    2011-09-01

    Perfluorocarbon nanoemulsions can target lipophilic therapeutic agents to solid tumors and simultaneously provide for monitoring nanocarrier biodistribution via ultrasonography and/or 19F MRI. In the first generation of block copolymer stabilized perfluorocarbon nanoemulsions, perfluoropentane (PFP) was used as the droplet forming compound. Although manifesting excellent therapeutic and ultrasound imaging properties, PFP nanoemulsions were unstable at storage, difficult to handle, and underwent droplet-to-bubble transition upon injection that was hard to control. To solve the above problems, perfluoro-15-crown-5-ether (PFCE) was used as a core forming compound in the second generation of block copolymer stabilized perfluorocarbon nanoemulsions. In the present paper, acoustic, imaging, and therapeutic properties of unloaded and paclitaxel (PTX) loaded PFCE nanoemulsions are reported. The size of paclitaxel-loaded PFCE nanodroplets (300 nm to 500 nm depending on emulsification conditions) favors their passive accumulation in tumor tissue. PFCE nanodroplets manifest both ultrasound and 19F MR contrast properties, which allows the use of multimodal imaging to monitor nanodroplet biodistribution. Ultrasonography and 19F MRI produced consistent results on nanodroplet biodistribution. Sonication with 1-MHz therapeutic ultrasound triggered reversible droplet-to-bubble transition in PFCE nanoemulsions. Microbubbles formed by acoustic vaporization underwent stable cavitation. In a pilot study on ultrasound-mediated therapy of a large breast cancer tumor, paclitaxel-loaded PFCE nanoemulsions combined with 1-MHz ultrasound (MI≥1.75) showed excellent therapeutic properties. Anticipated mechanisms of the observed effects are discussed.

  5. sup 19 F NMR studies of the D-galactose chemosensory receptor. (1) Sugar binding yields a global structural change

    SciTech Connect

    Luck, L.A.; Falke, J.J. )

    1991-04-30

    The Escherichia coli D-galactose and D-glucose receptor is an aqueous sugar-binding protein and the first component in the distinct chemosensory and transport pathways for these sugars. Activation of the receptor occurs when the sugar binds and induces a conformational change, which in turn enable docking to specific membrane proteins. Only the structure of the activated receptor containing bound D-glucose is known. To investigate the sugar-induced structural change, the authors have used {sup 19}F NMR to probe 12 sites widely distributed in the receptor molecule. Five sites are tryptophan positions probed by incorporation of 5-fluorotryptophan; the resulting {sup 19}F NMR resonances were assigned by site-directed mutagenesis. The other seven sites are phenylalanine positions probed by incorporation of 3-fluorophenylaline. Sugar binding to the substrate binding cleft was observed to trigger a global structural change detected via {sup 19}F NMR frequency shifts at 10 of the 12 labeled sites. The results are consistent with a model in which multiple secondary structural elements, known to extend between the substrate cleft and the protein surface, undergo shifts in their average positions upon sugar binding to the cleft. Such structural coupling provides a mechanism by which sugar binding to the substrate cleft can cause structural changes at one or more docking sites on the receptor surface.

  6. Fragment-Linking Approach Using (19)F NMR Spectroscopy To Obtain Highly Potent and Selective Inhibitors of β-Secretase.

    PubMed

    Jordan, John B; Whittington, Douglas A; Bartberger, Michael D; Sickmier, E Allen; Chen, Kui; Cheng, Yuan; Judd, Ted

    2016-04-28

    Fragment-based drug discovery (FBDD) has become a widely used tool in small-molecule drug discovery efforts. One of the most commonly used biophysical methods in detecting weak binding of fragments is nuclear magnetic resonance (NMR) spectroscopy. In particular, FBDD performed with (19)F NMR-based methods has been shown to provide several advantages over (1)H NMR using traditional magnetization-transfer and/or two-dimensional methods. Here, we demonstrate the utility and power of (19)F-based fragment screening by detailing the identification of a second-site fragment through (19)F NMR screening that binds to a specific pocket of the aspartic acid protease, β-secretase (BACE-1). The identification of this second-site fragment allowed the undertaking of a fragment-linking approach, which ultimately yielded a molecule exhibiting a more than 360-fold increase in potency while maintaining reasonable ligand efficiency and gaining much improved selectivity over cathepsin-D (CatD). X-ray crystallographic studies of the molecules demonstrated that the linked fragments exhibited binding modes consistent with those predicted from the targeted screening approach, through-space NMR data, and molecular modeling. PMID:26978477

  7. Bayesian Magic in Asteroseismology

    NASA Astrophysics Data System (ADS)

    Kallinger, T.

    2015-09-01

    Only a few years ago asteroseismic observations were so rare that scientists had plenty of time to work on individual data sets. They could tune their algorithms in any possible way to squeeze out the last bit of information. Nowadays this is impossible. With missions like MOST, CoRoT, and Kepler we basically drown in new data every day. To handle this in a sufficient way statistical methods become more and more important. This is why Bayesian techniques started their triumph march across asteroseismology. I will go with you on a journey through Bayesian Magic Land, that brings us to the sea of granulation background, the forest of peakbagging, and the stony alley of model comparison.

  8. Revealing ontological commitments by magic.

    PubMed

    Griffiths, Thomas L

    2015-03-01

    Considering the appeal of different magical transformations exposes some systematic asymmetries. For example, it is more interesting to transform a vase into a rose than a rose into a vase. An experiment in which people judged how interesting they found different magic tricks showed that these asymmetries reflect the direction a transformation moves in an ontological hierarchy: transformations in the direction of animacy and intelligence are favored over the opposite. A second and third experiment demonstrated that judgments of the plausibility of machines that perform the same transformations do not show the same asymmetries, but judgments of the interestingness of such machines do. A formal argument relates this sense of interestingness to evidence for an alternative to our current physical theory, with magic tricks being a particularly pure source of such evidence. These results suggest that people's intuitions about magic tricks can reveal the ontological commitments that underlie human cognition. PMID:25490128

  9. Site-specific solvent exposure analysis of a membrane protein using unnatural amino acids and {sup 19}F nuclear magnetic resonance

    SciTech Connect

    Shi, Pan; Li, Dong; Chen, Hongwei; Xiong, Ying; Tian, Changlin

    2011-10-22

    Highlights: {yields} Solvent isotope shift analysis of {sup 19}F-tfmF in different H{sub 2}O/D{sub 2}O molar ratio. {yields} Correlation between solvent isotope shift of {sup 19}F-spins and solvent exposure analysis. {yields} Solvent exposure analysis of membrane proteins. -- Abstract: Membrane proteins play an essential role in cellular metabolism, transportation and signal transduction across cell membranes. The scarcity of membrane protein structures has thus far prevented a full understanding of their molecular mechanisms. Preliminary topology studies and residue solvent exposure analysis have the potential to provide valuable information on membrane proteins of unknown structure. Here, a {sup 19}F-containing unnatural amino acid (trimethylfluoro-phenylalanine, tfmF) was applied to accomplish site-specific {sup 19}F spin incorporation at different sites in diacylglycerol kinase (DAGK, an Escherichia coli membrane protein) for site-specific solvent exposure analysis. Due to isotope effect on {sup 19}F spins, a standard curve for {sup 19}F-tfmF chemical shifts was drawn for varying solvent H{sub 2}O/D{sub 2}O ratios. Further site-specific {sup 19}F solvent isotope shift analysis was conducted for DAGK to distinguish residues in water-soluble loops, interfacial areas or hydrophobic membrane regions. This site-specific solvent exposure analysis method could be applied for further topological analysis of other membrane proteins.

  10. Interstellar Travel without 'Magic'

    NASA Astrophysics Data System (ADS)

    Woodcock, G.

    The possibility of interstellar space travel has become a popular subject. Distances of light years are an entirely new realm for human space travel. New means of propulsion are needed. Speculation about propulsion has included "magic", space warps, faster-than-light travel, known physics such as antimatter for which no practical implementation is known and also physics for which current research offers at least a hint of implementation, i.e. fusion. Performance estimates are presented for the latter and used to create vehicle concepts. Fusion propulsion will mean travel times of hundreds of years, so we adopt the "space colony" concepts of O'Neill as a ship design that could support a small civilization indefinitely; this provides the technical means. Economic reasoning is presented, arguing that development and production of "space colony" habitats for relief of Earth's population, with addition of fusion engines, will lead to vessels that can go interstellar. Scenarios are presented and a speculative estimate of a timetable is given.

  11. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers. PMID:26486514

  12. Magnetism, optical absorbance, and 19F NMR spectra of nafion films with self-assembling paramagnetic networks

    SciTech Connect

    Levin, E. M.; Chen, Q.; Bud'ko, S. L.

    2012-01-15

    Magnetization, optical absorbance, and {sup 19}F NMR spectra of Nafion transparent films as received and doped with Mn{sup 2+}, Co{sup 2+}, Fe{sup 2+}, and Fe{sup 3+} ions with and without treatment in 1H-1,2,4-triazole (trz) have been studied. Doping of Nafion with Fe{sup 2+} and Co{sup 2+} and their bridging to nitrogen of triazole yields a hybrid self-assembling paramagnetic system that exhibits interesting magnetic and optical properties. These include spin crossover phenomena between high-spin (HS) and low-spin (LS) states in Nafion-Fe{sup 2+}-trz and Nafion-Co{sup 2+}-trz accompanied by thermochromic effects in the visible range induced by temperature. A large shift of the magnetization curve induced by a magnetic field in the vicinity of the HS {leftrightarrow} LS, {approx}220 K, observed for Nafion-Fe{sup 2+}-trz has a rate of {approx}6 K/kOe, which is about three orders of magnitude larger than that in bulk spin crossover Fe{sup 2+} materials. Selective response of {sup 19}F NMR signals on doping with paramagnetic ions demonstrates that NMR can be used as spatially resolved method to study Nafion film with paramagnetic network. Both chemical shift and width of {sup 19}F NMR signals show that SO groups of Nafion, Fe or Co ions, and nitrogen of triazole are bonded whereas they form a spin crossover system. Based on a model of nanosize cylinders proposed for Nafion [K. Schmidt-Rohr and Q. Chen, Nat Mater (2008), 75], we suggest that paramagnetic ions are located inside these cylinders, forming self-assembling magnetically and optically active nanoscale networks.

  13. 19F nuclear magnetic resonance as a probe of the spatial relationship between the heme iron of cytochrome P-450 and its substrate.

    PubMed

    Crull, G B; Kennington, J W; Garber, A R; Ellis, P D; Dawson, J H

    1989-02-15

    The distance between the heme iron of ferrous cytochrome P-450-CAM and a fluorine label attached to the 9-methyl carbon of its substrate, (1R)-(+)-camphor, has been determined using 19F NMR. This investigation uses the Solomon-Bloembergen equation to measure the distance from a paramagnetic heme iron to a fluorine probe incorporated into a substrate that is not in fast exchange. The structural identity of the substrate analogue, 9-fluorocamphor, has been established using one- and two-dimensional NMR methods and mass spectrometry. The relaxation rate of 9-fluorocamphor bound to high-spin paramagnetic ferrous P-450-CAM has been studied at 188, 282, and 376 MHz, and the correlation time has been directly determined from the frequency dependence of the relaxation rate. When the substrate analogue was bound to the low-spin diamagnetic ferrous-CO derivative of the enzyme, the relaxation rate was found to be 100 times slower and was therefore neglected in the distance calculation. The relaxation data for the paramagnetic system and the correlation time have been used to calculate a distance of 3.8 A between the heme iron and the C-9 fluoride. A fit of the distance and the chemical shift data to the pseudocontact shift equation predicts an angle of approximately 52 degrees between the heme normal and the Fe-F vector. The solution state Fe-F distance is somewhat shorter and the angle between the heme normal and the Fe-F vector slightly larger for the substrate-bound ferrous enzyme reported herein than the analogous values for the substrate-bound ferric enzyme determined in the solid state by x-ray crystallography. These differences may reflect a structural change at the substrate-binding site upon reduction of the iron. PMID:2914926

  14. Fission fragment angular distribution for the 19F+197Au fusion-fission reaction at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Tripathi, R.; Sudarshan, K.; Sodaye, S.; Reddy, A. V.; Mahata, K.; Goswami, A.

    2005-04-01

    Angular distribution of fission fragments have been measured for 19F+197Au reaction at bombarding energies from 91 to 110 MeV. Fission fragment angular distributions have been calculated by transition state model with the transmission coefficients obtained using the coupled-channels theory. The calculated angular anisotropies are in good agreement with the experimental anisotropies. The experimental fission cross sections have also been reproduced on the basis of the coupled-channels theory. The results of angular distribution measurement do not show any significant contribution from quasifission as was reported in the literature based on the measurement of evaporation residues and mass distribution.

  15. Abject Magic: Reasoning Madness in Justine Larbalestier's "Magic or Madness" Trilogy

    ERIC Educational Resources Information Center

    Potter, Troy

    2013-01-01

    This paper explores the representation of magic and madness in Justine Larbalestier's "Magic or Madness" trilogy (2005-2007). Throughout the series, magic is constructed as an abject and disabling force that threatens to disable magic-wielders, either through madness or death. Despite being represented as a ubiquitous force, the…

  16. Airbag Trail Dubbed 'Magic Carpet'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Click on the image for Airbag Trail Dubbed 'Magic Carpet' (QTVR)

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Magic Carpet Close-upMagic Carpet Close-up HD

    This section of the first color image from the Mars Exploration Rover Spirit has been further processed to produce a sharper look at a trail left by the one of rover's airbags. The drag mark was made after the rover landed and its airbags were deflated and retracted. Scientists have dubbed the region the 'Magic Carpet' after a crumpled portion of the soil that appears to have been peeled away (lower left side of the drag mark). Rocks were also dragged by the airbags, leaving impressions and 'bow waves' in the soil. The mission team plans to drive the rover over to this site to look for additional clues about the composition of the martian soil. This image was taken by Spirit's panoramic camera.

    This extreme close-up image (see insets above) highlights the martian feature that scientists have named 'Magic Carpet' because of its resemblance to a crumpled carpet fold. Scientists think the soil here may have detached from its underlying layer, possibly due to interaction with the Mars Exploration Rover Spirit's airbag after landing. This image was taken on Mars by the rover's panoramic camera.

  17. Finding All Solutions to the Magic Hexagram

    ERIC Educational Resources Information Center

    Holland, Jason; Karabegov, Alexander

    2008-01-01

    In this article, a systematic approach is given for solving a magic star puzzle that usually is accomplished by trial and error or "brute force." A connection is made to the symmetries of a cube, thus the name Magic Hexahedron.

  18. A General and Facile Strategy to Fabricate Multifunctional Nanoprobes for Simultaneous (19)F Magnetic Resonance Imaging, Optical/Thermal Imaging, and Photothermal Therapy.

    PubMed

    Hu, Gaofei; Li, Nannan; Tang, Juan; Xu, Suying; Wang, Leyu

    2016-09-01

    (19)F magnetic resonance imaging (MRI), due to its high sensitivity and negligible background, is anticipated to be a powerful noninvasive, sensitive, and accurate molecular imaging technique. However, the major challenge of (19)F MRI is to increase the number of (19)F atoms while maintaining the solubility and molecular mobility of the probe. Here, we successfully developed a facile and general strategy to synthesize the multifunctional (19)F MRI nanoprobes by encapsulating the hydrophobic inorganic nanoparticles (NPs) into a hybrid polymer micelle consisting of hydrolysates of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDTES) and oleylamine-functionalized poly(succinimide) (PSIOAm). Due to their good water dispersibility, excellent molecular mobility resulting from the ultrathin coating, and high (19)F atom numbers, these nanoprobes generate a separate sharp singlet of (19)F nuclear magnetic resonance (NMR) signal (at -82.8 ppm) with half peak width of ∼28 Hz, which is highly applicable for (19)F MRI. Significantly, by varying the inorganic core from metals (Au), oxides (Fe3O4), fluorides (NaYF4:Yb(3+)/Er(3+)), and phosphates (YPO4) to semiconductors (Cu7S4 and Ag2S, ZnS:Mn(2+)) NPs, which renders the nanoprobes' multifunctional properties such as photothermal ability (Au, Cu7S4), magnetism (Fe3O4), fluorescence (ZnS:Mn(2+)), near-infrared (NIR) fluorescence (Ag2S), and upconversion (UC) luminescence. Meanwhile, the as-prepared nanoprobes possess relatively small sizes (about 50 nm), which is beneficial for long-time circulation. The proof-of-concept in vitro (19)F NMR and photothermal ablation of ZnS:Mn(2+)@PDTES/PSIOAm and Cu7S4@PDTES/PSIOAm nanoprobes further suggest that these nanoprobes hold wide potentials for multifunctional applications in biomedical fields. PMID:27534896

  19. Superfluorinated PEI Derivative Coupled with (99m) Tc for ASGPR Targeted (19) F MRI/SPECT/PA Tri-Modality Imaging.

    PubMed

    Guo, Zhide; Gao, Mengna; Song, Manli; Li, Yesen; Zhang, Deliang; Xu, Duo; You, Linyi; Wang, Liangliang; Zhuang, Rongqiang; Su, Xinhui; Liu, Ting; Du, Jin; Zhang, Xianzhong

    2016-07-01

    Fluorinated polyethylenimine derivative labeled with radionuclide (99m) Tc is developed as a (19) F MRI/SPECT/PA multifunctional imaging agent with good asialoglycoprotein receptors (ASGPR)-targeting ability. This multifunctional agent is safe and suitable for (19) F MRI/SPECT/PA imaging and has the potential to detect hepatic diseases and to assess liver function, which provide powerful support for the development of personalized and precision medicine. PMID:27159903

  20. Phospho-selective mechanisms of arrestin conformations and functions revealed by unnatural amino acid incorporation and 19F-NMR

    PubMed Central

    Yang, Fan; Yu, Xiao; Liu, Chuan; Qu, Chang-Xiu; Gong, Zheng; Liu, Hong-Da; Li, Fa-Hui; Wang, Hong-Mei; He, Dong-Fang; Yi, Fan; Song, Chen; Tian, Chang-Lin; Xiao, Kun-Hong; Wang, Jiang-Yun; Sun, Jin-Peng

    2015-01-01

    Specific arrestin conformations are coupled to distinct downstream effectors, which underlie the functions of many G-protein-coupled receptors (GPCRs). Here, using unnatural amino acid incorporation and fluorine-19 nuclear magnetic resonance (19F-NMR) spectroscopy, we demonstrate that distinct receptor phospho-barcodes are translated to specific β-arrestin-1 conformations and direct selective signalling. With its phosphate-binding concave surface, β-arrestin-1 ‘reads' the message in the receptor phospho-C-tails and distinct phospho-interaction patterns are revealed by 19F-NMR. Whereas all functional phosphopeptides interact with a common phosphate binding site and induce the movements of finger and middle loops, different phospho-interaction patterns induce distinct structural states of β-arrestin-1 that are coupled to distinct arrestin functions. Only clathrin recognizes and stabilizes GRK2-specific β-arrestin-1 conformations. The identified receptor-phospho-selective mechanism for arrestin conformation and the spacing of the multiple phosphate-binding sites in the arrestin enable arrestin to recognize plethora phosphorylation states of numerous GPCRs, contributing to the functional diversity of receptors. PMID:26347956

  1. Fragment Screening and Druggability Assessment for the CBP/p300 KIX Domain Via Protein Observed 19F NMR

    PubMed Central

    Gee, Clifford T.; Koleski, Edward J.

    2015-01-01

    19F NMR of labeled proteins is a sensitive method for characterizing structure, conformational dynamics, higher-order assembly, and ligand binding. Fluorination of aromatic side chains has been suggested as a labeling strategy for small molecule ligand discovery for protein-protein interaction interfaces. Using a model transcription factor binding domain of the CREB binding protein (CBP)/p300, KIX, we report the first full small molecule screen using protein-observed 19F NMR. Screening of 508 compounds and validation by 1H-15N HSQC NMR led to the identification of a minimal pharmacaphore for the MLL-KIX interaction site. Hit rate analysis for the CREB-KIX and MLL-KIX sites provided a metric to assess the ligandability or “druggability” of each interface informing future medicinal chemistry efforts. The structural information from the simplified spectra and data collection speed, affords a new screening tool for analysis of protein interfaces and discovery of small molecules. PMID:25651535

  2. Magical attachment: Children in magical relations with hospital clowns

    PubMed Central

    2012-01-01

    The aim of the present study was to achieve a theoretical understanding of several different-age children's experiences of magic relations with hospital clowns in the context of medical care, and to do so using psychological theory and a child perspective. The method used was qualitative and focused on nine children. The results showed that age was important to consider in better understanding how the children experienced the relation with the hospital clowns, how they described the magical aspects of the encounter and how they viewed the importance of clown encounters to their own well-being. The present theoretical interpretation characterized the encounter with hospital clowns as a magical safe area, an intermediate area between fantasy and reality. The discussion presented a line of reasoning concerning a magical attachment between the child and the hospital clowns, stating that this attachment: a) comprised a temporary relation; b) gave anonymity; c) entailed reversed roles; and d) created an emotional experience of boundary-transcending opportunities. PMID:22371813

  3. Radiological properties of MAGIC normoxic polymer gel dosimetry

    NASA Astrophysics Data System (ADS)

    Aljamal, M.; Zakaria, A.; Shamsuddin, S.

    2013-04-01

    For a polymer gel dosimeter to be of use in radiation dosimetry, it should display water-equivalent radiological properties. In this study, the radiological properties of the MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gels were investigated. The mass density (ρ) was determined based on Archimedes' principle. The weight fraction of elemental composition and the effective atomic number (Zeff) were calculated. The electron density was also measured with 90° scattering angle at room temperature. The linear attenuation coefficient (μ) of unirradiated gel, irradiated gel, and water were determined using Am-241 based on narrow beam geometry. Monte Carlo simulation was used to calculate the depth doses response of MAGIC gel and water for 6MV photon beam. The weight fractions of elements composition of MAGIC gel were close to that for water. The mass density was found to be 1027 ± 2 kg m-3, which is also very close to mass density of muscle tissue (1030 kg m-3) and 2.7% higher than that of water. The electron density (ρe) and atomic number (Zeff) were found to be 3.43 × 1029 e m-3 and 7.105, respectively. The electron density measured was 2.6% greater than that for water. The atomic number was very close to that for water. The prepared MAGIC gel was found to be water equivalent based on the study of element composition, mass density, electron density and atomic number. The linear attenuation coefficient of unirradiated gel was very close to that of water. The μ of irradiated gel was found to be linear with dose 2-40 Gy. The depth dose response for MAGIC gel from a 6 MV photon beam had a percentage dose difference to water of less than 1%. Therefore it satisfies the criteria to be a good polymer gel dosimeter for radiotherapy.

  4. NbF{sub 5} and TaF{sub 5}: Assignment of {sup 19}F NMR resonances and chemical bond analysis from GIPAW calculations

    SciTech Connect

    Biswal, Mamata; Body, Monique; Legein, Christophe; Sadoc, Aymeric; Boucher, Florent

    2013-11-15

    The {sup 19}F isotropic chemical shifts (δ{sub iso}) of two isomorphic compounds, NbF{sub 5} and TaF{sub 5}, which involve six nonequivalent fluorine sites, have been experimentally determined from the reconstruction of 1D {sup 19}F MAS NMR spectra. In parallel, the corresponding {sup 19}F chemical shielding tensors have been calculated using the GIPAW method for both experimental and DFT-optimized structures. Furthermore, the [M{sub 4}F{sub 20}] units of NbF{sub 5} and TaF{sub 5} being held together by van der Waals interactions, the relevance of Grimme corrections to the DFT optimization processes has been evaluated. However, the semi-empirical dispersion correction term introduced by such a method does not show any significant improvement. Nonetheless, a complete and convincing assignment of the {sup 19}F NMR lines of NbF{sub 5} and TaF{sub 5} is obtained, ensured by the linearity between experimental {sup 19}F δ{sub iso} values and calculated {sup 19}F isotropic chemical shielding σ{sub iso} values. The effects of the geometry optimizations have been carefully analyzed, confirming among other matters, the inaccuracy of the experimental structure of NbF{sub 5}. The relationships between the fluorine chemical shifts, the nature of the fluorine atoms (bridging or terminal), the position of the terminal ones (opposite or perpendicular to the bridging ones), the fluorine charges, the ionicity and the length of the M–F bonds have been established. Additionally, for three of the {sup 19}F NMR lines of NbF{sub 5}, distorted multiplets, arising from {sup 1}J-coupling and residual dipolar coupling between the {sup 19}F and {sup 93}Nb nuclei, were simulated yielding to values of {sup 93}Nb–{sup 19}F {sup 1}J-coupling for the corresponding fluorine sites. - Graphical abstract: The complete assignment of the {sup 19}F NMR lines of NbF{sub 5} and TaF{sub 5} allow establishing relationships between the {sup 19}F δ{sub iso} values, the nature of the fluorine atoms

  5. GRB neutrino search with MAGIC

    SciTech Connect

    Becker, Julia K.; Rhode, Wolfgang; Gaug, Markus

    2008-05-22

    The Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope was designed for the detection of photon sources > or approx. 50 GeV. The measurement of highly-inclined air showers renders possible the search for high-energy neutrinos, too. Only neutrinos can traverse the Earth without interaction, and therefore, events close to the horizon can be identified as neutrino-induced rather than photon-induced or hadronic events. In this paper, Swift-XRT-detected GRBs with given spectral information are used in order to calculate the potential neutrino energy spectrum from prompt and afterglow emission for each individual GRB. The event rate in MAGIC is estimated assuming that the GRB happens within the field of view of MAGIC. A sample of 568 long GRBs as detected by BATSE is used to compare the detection rates with 163 Swift-detected bursts. BATSE has properties similar to the Gamma-ray Burst Monitor (GBM) on board of GLAST. Therefore the estimated rates give an estimate for the possibilities of neutrino detection with MAGIC from GLAST-triggered bursts.

  6. Magic and the School Counselor.

    ERIC Educational Resources Information Center

    Spruill, David A.; Poidevant, John M.

    1993-01-01

    Discusses philosophy used to build student interest in various lesson topics taught to guidance groups. Presents three magic activities complete with lesson plans: How to Change Big Problems into Little Ones and How to Keep Little Problems from Getting Bigger; Teaching Friendship Skills and Becoming Aware of Your Feelings; and What Does Your…

  7. (19)F MRSI of capecitabine in the liver at 7 T using broadband transmit-receive antennas and dual-band RF pulses.

    PubMed

    van Gorp, Jetse S; Seevinck, Peter R; Andreychenko, Anna; Raaijmakers, Alexander J E; Luijten, Peter R; Viergever, Max A; Koopman, Miriam; Boer, Vincent O; Klomp, Dennis W J

    2015-11-01

    Capecitabine (Cap) is an often prescribed chemotherapeutic agent, successfully used to cure some patients from cancer or reduce tumor burden for palliative care. However, the efficacy of the drug is limited, it is not known in advance who will respond to the drug and it can come with severe toxicity. (19)F Magnetic Resonance Spectroscopy (MRS) and Magnetic Resonance Spectroscopic Imaging (MRSI) have been used to non-invasively study Cap metabolism in vivo to find a marker for personalized treatment. In vivo detection, however, is hampered by low concentrations and the use of radiofrequency (RF) surface coils limiting spatial coverage. In this work, the use of a 7T MR system with radiative multi-channel transmit-receive antennas was investigated with the aim of maximizing the sensitivity and spatial coverage of (19)F detection protocols. The antennas were broadband optimized to facilitate both the (1)H (298 MHz) and (19)F (280 MHz) frequencies for accurate shimming, imaging and signal combination. B1(+) simulations, phantom and noise measurements showed that more than 90% of the theoretical maximum sensitivity could be obtained when using B1(+) and B1(-) information provided at the (1)H frequency for the optimization of B1(+) and B1(-) at the (19)F frequency. Furthermore, to overcome the limits in maximum available RF power, whilst ensuring simultaneous excitation of all detectable conversion products of Cap, a dual-band RF pulse was designed and evaluated. Finally, (19)F MRS(I) measurements were performed to detect (19)F metabolites in vitro and in vivo. In two patients, at 10 h (patient 1) and 1 h (patient 2) after Cap intake, (19)F metabolites were detected in the liver and the surrounding organs, illustrating the potential of the set-up for in vivo detection of metabolic rates and drug distribution in the body. PMID:26373355

  8. Study of viscosity on the fission dynamics of the excited nuclei 228U produced in 19F + 209Bi reactions

    NASA Astrophysics Data System (ADS)

    Eslamizadeh, H.

    2015-06-01

    A two-dimensional (2D) dynamical model based on Langevin equations was applied to study the fission dynamics of the compound nuclei 228U produced in 19F + 209Bi reactions at intermediate excitation energies. The distance between the centers of masses of the future fission fragments was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, K, was considered as the second dimension in Langevin dynamical calculations. The magnitude of post-saddle friction strength was inferred by fitting measured data on the average pre-scission neutron multiplicity for 228U. It was shown that the results of calculations are in good agreement with the experimental data by using values of the post-saddle friction equal to 6-8 × 1021s-1.

  9. (19)F NMR study of ligand dynamics in carboxylate-bridged diiron(II) complexes supported by a macrocyclic ligand.

    PubMed

    Minier, Mikael A; Lippard, Stephen J

    2015-11-01

    A series of asymmetrically carboxylate-bridged diiron(ii) complexes featuring fluorine atoms as NMR spectroscopic probes, [Fe2(PIM)(Ar(4F-Ph)CO2)2] (10), [Fe2(F2PIM)(Ar(Tol)CO2)2] (11), and [Fe2(F2PIM)(Ar(4F-Ph)CO2)2] (12), were prepared and characterized by X-ray crystallography, Mössbauer spectroscopy, and VT (19)F NMR spectroscopy. These complexes are part of a rare family of syn N-donor diiron(ii) compounds, [Fe2(X2PIM)(RCO2)2], that are structurally very similar to the active site of the hydroxylase enzyme component of reduced methane monooxygenase (MMOHred). Solution characterization of these complexes demonstrates that they undergo intramolecular carboxylate rearrangements, or carboxylate shifts, a dynamic feature relevant to the reactivity of the diiron centers in bacterial multicomponent monooxygenases. PMID:26418547

  10. 19F NMR Study of Ligand Dynamics in Carboxylate-Bridged Diiron(II) Complexes Supported by a Macrocyclic Ligand

    PubMed Central

    Minier, Mikael A.; Lippard, Stephen J.

    2015-01-01

    A series of asymmetrically carboxylate-bridged diiron(II) complexes featuring fluorine atoms as NMR spectroscopic probes, [Fe2(PIM)(Ar4F-PhCO2)2] (10), [Fe2(F2PIM)(ArTolCO2)2] (11), and [Fe2(F2PIM)(Ar4F-PhCO2)2] (12), were prepared and characterized by X-ray crystallography, Mössbauer spectroscopy, and VT 19F NMR spectroscopy. These complexes are part of a rare family of syn-N diiron(II) complexes, [Fe2(X2PIM)(RCO2)2], that are structurally very similar to the active site of the hydroxylase enzyme component of reduced methane monooxygenase (MMOHred). Solution characterization of these complexes demonstrates that they undergo intramolecular carboxylate rearrangements, or carboxylate shifts, a dynamic feature relevant to the reactivity of the diiron centers in bacterial multicomponent monooxygenases. PMID:26418547

  11. Nuclear relaxation rates study of GTP(gamma F)-tubulin interaction using 19F-nuclear magnetic resonance.

    PubMed

    Monasterio, O

    1989-07-01

    To study the relationship between the exchangeable GTP binding site (E-site) and the high affinity metal binding site we synthesized P3-fluoro P1-5'-guanosine tripaosphate (GTP(gamma F), an analog of GTP. Our results show that this analog binds to the exchangeable GTP binding site of calf brain tubulin. The values of the dissociation constant and the stoichiometry of the GTP(gamma F)-Mn(II) complex as determined by EPR spectroscopy were 1.64 x 10(-4) M and one mole of manganese per mole of nucleotide, respectively. The distance separating the high-affinity binding site for the divalent metal ion and the exchangeable nucleotide binding site was evaluated by using high-resolution 19F-NMR. The 31P- and 19F-NMR spectra of GTP(gamma F) were studied, both the fluorine and the gamma-phosphate were split in a doublet with a coupling constant of 936 Hz. Tubulin purified by the method of Weisenberg (Weisenberg, R.C., and Timashef, S.N. (1970) Biochemistry 9, 4110-4116) was treated with colchicine to stabilize it, GTP(gamma F) was added and the 254.1 MHz 19fluorine relaxation rates measured within the first four hours. Longitudinal and transversal relaxation rates were determined in the presence of colchicine-tubulin-Mn(II), (paramagnetic complex), or the ternary complex with magnesium (diamagnetic complex). The analysis of the temperature-dependent relaxation data indicates that the metal and the exchangeable nucleotide binding sites are separated by a maximal distance of 6 at 35 degrees C, to 8.1 A at 12 degrees C. PMID:2619317

  12. Intracellular pH of perfused single frog skin: combined 19F- and 31P-NMR analysis.

    PubMed

    Civan, M M; Lin, L E; Peterson-Yantorno, K; Taylor, J; Deutsch, C

    1984-11-01

    Intracellular pH (pHc) has been determined in frog skin by applying two different methods of pH measurement, 19F and 31P nuclear magnetic resonance (NMR) analysis, to the same tissues. Results from both NMR approaches confirm an observation by Lin, Shporer, and Civan [Am. J. Physiol. 248 (Cell Physiol. 17): 1985] that acidification of the extracellular medium reverses the sign of the pH gradient present under baseline conditions. The fluorinated probe, alpha-(difluoromethyl)-alanine methyl ester, was introduced into the epithelial cells by preincubating skins for 4.7-10.4 h at room temperature in Ringer solutions containing 1 mM ester. The free amino acid was subsequently released by intracellular esterase activity, thus providing a high enough probe concentration for NMR analysis to be practicable. From measurements of short-circuit current and transepithelial resistance under base-line and experimental conditions and the appearance of phosphocreatine (PCr) in the 31P spectrum of preloaded tissues, the fluorinated probe appears to be nontoxic to frog skin. Measurement of the chemical shift of methylphosphonate relative to PCr permitted calculation of extracellular pH. Estimation of the intracellular pH was performed both by measurement of the chemical shift of inorganic phosphate (Pi) relative to PCr and by measurement of the central peak spacing of the 19F spectrum. From four direct comparisons of the two techniques in two experiments, the difference in the estimated pH was only 0.03 +/- 0.07 pH units, supporting the concept that 31P-NMR analysis is a valid method of measuring pH in this tissue. PMID:6496729

  13. Incomplete fusion studies in the 19F+159Tb system at low energies and its correlation with various systematics

    NASA Astrophysics Data System (ADS)

    Shuaib, Mohd.; Sharma, Vijay R.; Yadav, Abhishek; Singh, Pushpendra P.; Sharma, Manoj Kumar; Singh, Devendra P.; Kumar, R.; Singh, R. P.; Muralithar, S.; Singh, B. P.; Prasad, R.

    2016-07-01

    The excitation functions of reaction residues populated via the complete fusion and incomplete fusion process in the interaction of the 19F+159Tb system have been measured at energies ≈4 -6 MeV/nucleon, using off-line γ -ray spectroscopy. The analysis of data was done within the framework of statistical model code pace4 (a compound nucleus model). A significant fraction of incomplete fusion was observed in the production of reaction residues involving α particle(s) in the exit channels, even at energies as low as near the Coulomb barrier. The incomplete fusion strength function was deduced from the experimental excitation functions and the dependence of this strength function on various entrance channel parameters was studied. The present results show a strong dependence on the projectile α -Q value that agrees well with the existing data. To probe the dependence of incomplete fusion on entrance channel mass asymmetry, the present work was compared with the results obtained in the interaction of 12C, 16O, and 19F with nearby targets available in the literature. It was observed that the mass asymmetry linearly increases for each projectile separately and turns out to be a projectile-dependent mass-asymmetry systematics. The deduced incomplete fusion strength functions in the present work are also plotted as a function of ZPZT (Coulomb effect) and compared with the existing literature. A strong dependence of the Coulomb effect on the incomplete fusion fraction was observed. It was found that the fraction of incomplete fusion linearly increases with ZPZT and was found to be more for larger ZPZT values indicating significantly important linear systematics.

  14. Indocyanine green-loaded perfluorocarbon nanoemulsions for bimodal 19F-magnetic resonance/nearinfrared fluorescence imaging and subsequent phototherapy

    PubMed Central

    Wang, Yuan-Guo; Kim, Hyunjin; Mun, Saehun

    2013-01-01

    We have developed an indocyanine green-loaded perfluorocarbon (ICG/PFCE) nanoemulsion as a multifunctional theranostic nanomedicine which enables not only 19F magnetic resonance (MR)/near-infrared fluorescence (NIRF) bimodal imaging but also subsequent photodynamic/photothermal dual therapy of cancer. The hydrodynamic size of ICG/PFCE nanoemulsions was 164.2 nm. The stability of indocyanine green (ICG) in aqueous solution was significantly improved when loaded on perfluorocarbon nanoemulsions. In addition, ICG/PFCE nanoemulsions showed good dispersion stability in aqueous media containing 10% fetal bovine serum, for at least 14 days. 19F-MRI of ICG/PFCE nanoemulsions showed that the signal intensity increased with increasing nanoemulsion concentration with no signal observed from the surrounding background. Using NIRF imaging with perfluorocarbon nanoemulsion alone, without ICG, did not produce NIRF, while clear and bright fluorescent images were obtained with ICG/PFCE nanoemulsions at 10-µM ICG equivalent. The capacity of ICG-loaded nanoemulsions to generate heat following light irradiation by using an 810-nm laser was comparable to that of free ICG, while singlet oxygen generation of ICG-loaded nanoemulsions was significantly better than that of free ICG. In vitro cytotoxicity tests and fluorescence microscopy confirmed biocompatibility of the nanoemulsion. Upon light irradiation, U87MG glioblastoma cells incubated with ICG/PFCE nanoemulsions underwent necrotic cell death. The therapeutic mechanism during light illumination appears to be mainly due to the photodynamic effect at lower ICG concentrations, whilst the photothermal effect became more obvious at increased ICG concentrations, enabling combined photodynamic/photothermal therapy of cancer cells. PMID:23833726

  15. Imaging Neuroinflammation In Vivo in a Neuropathic Pain Rat Model with Near-Infrared Fluorescence and 19F Magnetic Resonance

    PubMed Central

    Vasudeva, Kiran; Andersen, Karl; Zeyzus-Johns, Bree; Hitchens, T. Kevin; Patel, Sravan Kumar; Balducci, Anthony; Janjic, Jelena M.; Pollock, John A.

    2014-01-01

    Chronic neuropathic pain following surgery represents a serious worldwide health problem leading to life-long treatment and the possibility of significant disability. In this study, neuropathic pain was modeled using the chronic constriction injury (CCI). The CCI rats exhibit mechanical hypersensitivity (typical neuropathic pain symptom) to mechanical stimulation of the affected paw 11 days post surgery, at a time when sham surgery animals do not exhibit hypersensitivity. Following a similar time course, TRPV1 gene expression appears to rise with the hypersensitivity to mechanical stimulation. Recent studies have shown that immune cells play a role in the development of neuropathic pain. To further explore the relationship between neuropathic pain and immune cells, we hypothesize that the infiltration of immune cells into the affected sciatic nerve can be monitored in vivo by molecular imaging. To test this hypothesis, an intravenous injection of a novel perfluorocarbon (PFC) nanoemulsion, which is phagocytosed by inflammatory cells (e.g. monocytes and macrophages), was used in a rat CCI model. The nanoemulsion carries two distinct imaging agents, a near-infrared (NIR) lipophilic fluorescence reporter (DiR) and a 19F MRI (magnetic resonance imaging) tracer, PFC. We demonstrate that in live rats, NIR fluorescence is concentrated in the area of the affected sciatic nerve. Furthermore, the 19F MRI signal was observed on the sciatic nerve. Histological examination of the CCI sciatic nerve reveals significant infiltration of CD68 positive macrophages. These results demonstrate that the infiltration of immune cells into the sciatic nerve can be visualized in live animals using these methods. PMID:24587398

  16. Cross sections for proton induced high energy γ -ray emission (PIGE) in reaction 19 F(p, αγ)16 O at incident proton energies between 1.5 and 4 MeV

    NASA Astrophysics Data System (ADS)

    Cabanelas, P.; Cruz, J.; Fonseca, M.; Henriques, A.; Lourenço, F.; Luís, H.; Machado, J.; Pires Ribeiro, J.; Sánchez-Benítez, A. M.; Teubig, P.; Velho, P.; Zarza-Moreno, M.; Galaviz, D.; Jesus, A. P.

    2016-08-01

    We have studied the high energy gamma-rays produced in the reaction 19 F(p, αγ)16 O for incident proton energies from 1.5 to 4.0 MeV over NaF/Ag and CaF2/Ag thin targets in two different sets of data. Gamma-rays were detected with a High Purity Ge detector with an angle of 130° with respect to the beam axis. The cross-sections for the high energy gamma-rays of 6.129, 6.915 and 7.115 MeV have been measured for the whole group between 5 and 7.2 MeV with accuracy better than 10%. A new energy range was covered and more points are included in the cross-sections data base expanding the existing set of data. Results are in agreement with previous measurements in similar conditions.

  17. Magic star puzzle for educational mathematics

    NASA Astrophysics Data System (ADS)

    Gan, Yee Siang; Fong, Wan Heng; Sarmin, Nor Haniza

    2013-04-01

    One of the interesting fields in recreational mathematics is the magic number arrangement. There are different kinds of arrays in the arrangement for a group of numbers. In particular, one of the arrays in magic number arrangement is called magic star. In fact, magic star involves combinatorics that contributes to geometrical analysis and number theory. Hence, magic star is suitable to be introduced as educational mathematics to cultivate interest in different area of mathematics. To obtain the solutions of normal magic stars of order six, the possible sets of numbers for every line in a magic star have been considered. Previously, the calculation for obtaining the solutions has been done manually which is time-consuming. Therefore, a programming code to generate all the fundamental solutions for normal magic star of order six without including the properties of rotation and reflection has been done. In this puzzle, a magic star puzzle is created by using Matlab software, which enables a user to verify the entries for the cells of magic star of order six. Moreover, it is also user-friendly as it provides interactive commands on the inputs given by the user, which enables the user to detect the incorrect inputs. In addition, user can also choose to view all the fundamental solutions as generated by the programming code.

  18. (19)F(alpha,n)(22)Na, (22)Ne(p,n)(22)Na, and the Role of their Inverses in the Destruction of (22)Na

    NASA Astrophysics Data System (ADS)

    Wrean, Patricia Rose

    The inverses of the 19F(α,n)22Na and 22Ne(p,n)22Na reactions may be important destruction mechanisms for 22Na in neutron-rich, high-temperature or explosive nucleosynthesis. I have measured the cross sections for the 19F(α,n)22Na and 22Ne(p,n)22Na reactions from threshold to 3.1 and 5.4 MeV, respectively. The absolute efficiency of the 4π neutron detector was determined by Monte Carlo calculations and calibrated using two standard sources and two nuclear reactions. Cross sections for the inverse reactions have been calculated using the principle of detailed balance, and reaction rates for both the reactions and their inverses determined for temperatures between 0.01 and 10 GK for 19F(α,n)22Na and between 0.1 and 10 GK for 22Ne(p,n)22Na.

  19. Application of /sup 19/F nuclear magnetic resonance to examine covalent modification reactions of tyrosyl derivatives: a study of calcineurin catalysis

    SciTech Connect

    Martin, B.L.; Graves, D.J.

    1988-04-01

    The hydrolysis of fluorotyrosine phosphate by the calmodulin-activated phosphatase calcineurin has been monitored by /sup 19/F nuclear magnetic resonance spectroscopy. Previous work had established that the /sup 19/F nuclear magnetic resonance shift of the fluorine nucleus was altered after the phosphorylation of the phenolic hydroxyl group. The disappearance of substrate and the appearance of product can be measured simultaneously with this approach. Application of the integrated form of the Michaelis-Menten equation yields estimates of the kinetic parameter, K/sub M/, close to the values obtained by initial rate kinetics. The velocity term, V/sub M/ was also evaluated to be approximately the same value. Calcineurin was determined not to be inactivated over the time period of the reaction. The results demonstrate that /sup 19/F nuclear magnetic resonance spectroscopy can be applied to the examination of enzyme-catalyzed reactions.

  20. Towards a science of magic.

    PubMed

    Kuhn, Gustav; Amlani, Alym A; Rensink, Ronald A

    2008-09-01

    It is argued here that cognitive science currently neglects an important source of insight into the human mind: the effects created by magicians. Over the centuries, magicians have learned how to perform acts that are perceived as defying the laws of nature, and that induce a strong sense of wonder. This article argues that the time has come to examine the scientific bases behind such phenomena, and to create a science of magic linked to relevant areas of cognitive science. Concrete examples are taken from three areas of magic: the ability to control attention, to distort perception, and to influence choice. It is shown how such knowledge can help develop new tools and indicate new avenues of research into human perception and cognition. PMID:18693130

  1. Magic Carpet Shows Its Colors

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The upper left image in this display is from the panoramic camera on the Mars Exploration Rover Spirit, showing the 'Magic Carpet' region near the rover at Gusev Crater, Mars, on Sol 7, the seventh martian day of its journey (Jan. 10, 2004). The lower image, also from the panoramic camera, is a monochrome (single filter) image of a rock in the 'Magic Carpet' area. Note that colored portions of the rock correlate with extracted spectra shown in the plot to the side. Four different types of materials are shown: the rock itself, the soil in front of the rock, some brighter soil on top of the rock, and some dust that has collected in small recesses on the rock face ('spots'). Each color on the spectra matches a line on the graph, showing how the panoramic camera's different colored filters are used to broadly assess the varying mineral compositions of martian rocks and soils.

  2. Secrets of the Chinese magic mirror replica

    NASA Astrophysics Data System (ADS)

    Mak, Se-yuen; Yip, Din-yan

    2001-03-01

    We examine the structure of five Chinese magic mirror replicas using a special imaging technique developed by the authors. All mirrors are found to have a two-layered structure. The reflecting surface that gives rise to a projected magic pattern on the screen is hidden under a polished half-reflecting top layer. An alternative method of making the magic mirror using ancient technology has been proposed. Finally, we suggest a simple method of reconstructing a mirror replica in the laboratory.

  3. Verification of threshold activation detection (TAD) technique in prompt fission neutron detection using scintillators containing 19F

    NASA Astrophysics Data System (ADS)

    Sibczynski, P.; Kownacki, J.; Moszyński, M.; Iwanowska-Hanke, J.; Syntfeld-Każuch, A.; Gójska, A.; Gierlik, M.; Kaźmierczak, Ł.; Jakubowska, E.; Kędzierski, G.; Kujawiński, Ł.; Wojnarowicz, J.; Carrel, F.; Ledieu, M.; Lainé, F.

    2015-09-01

    In the present study ⌀ 5''× 3'' and ⌀ 2''× 2'' EJ-313 liquid fluorocarbon as well as ⌀ 2'' × 3'' BaF2 scintillators were exposed to neutrons from a 252Cf neutron source and a Sodern Genie 16GT deuterium-tritium (D+T) neutron generator. The scintillators responses to β- particles with maximum endpoint energy of 10.4 MeV from the n+19F reactions were studied. Response of a ⌀ 5'' × 3'' BC-408 plastic scintillator was also studied as a reference. The β- particles are the products of interaction of fast neutrons with 19F which is a component of the EJ-313 and BaF2 scintillators. The method of fast neutron detection via fluorine activation is already known as Threshold Activation Detection (TAD) and was proposed for photofission prompt neutron detection from fissionable and Special Nuclear Materials (SNM) in the field of Homeland Security and Border Monitoring. Measurements of the number of counts between 6.0 and 10.5 MeV with a 252Cf source showed that the relative neutron detection efficiency ratio, defined as epsilonBaF2 / epsilonEJ-313-5'', is 32.0% ± 2.3% and 44.6% ± 3.4% for front-on and side-on orientation of the BaF2, respectively. Moreover, the ⌀ 5'' EJ-313 and side-on oriented BaF2 were also exposed to neutrons from the D+T neutron generator, and the relative efficiency epsilonBaF2 / epsilonEJ-313-5'' was estimated to be 39.3%. Measurements of prompt photofission neutrons with the BaF2 detector by means of data acquisition after irradiation (out-of-beam) of nuclear material and between the beam pulses (beam-off) techniques were also conducted on the 9 MeV LINAC of the SAPHIR facility.

  4. Multinucleon transfer in O,1816,19F+208Pb reactions at energies near the fusion barrier

    NASA Astrophysics Data System (ADS)

    Rafferty, D. C.; Dasgupta, M.; Hinde, D. J.; Simenel, C.; Simpson, E. C.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; McNeil, S. D.; Ramachandran, K.; Vo-Phuoc, K.; Wakhle, A.

    2016-08-01

    Background: Nuclear reactions are complex, involving collisions between composite systems where many-body dynamics determines outcomes. Successful models have been developed to explain particular reaction outcomes in distinct energy and mass regimes, but a unifying picture remains elusive. The irreversible transfer of kinetic energy from the relative motion of the collision partners to their internal states, as is known to occur in deep inelastic collisions, has yet to be successfully incorporated explicitly into fully quantal reaction models. The influence of these processes on fusion is not yet quantitatively understood. Purpose: To investigate the population of high excitation energies in transfer reactions at sub-barrier energies, which are precursors to deep inelastic processes, and their dependence on the internuclear separation. Methods: Transfer probabilities and excitation energy spectra have been measured in collisions of O,1816,19F+208Pb , at various energies below and around the fusion barrier, by detecting the backscattered projectile-like fragments in a Δ E -E telescope. Results: The relative yields of different transfer outcomes are strongly driven by Q values, but change with the internuclear separation. In 16O+208Pb , single nucleon transfer dominates, with a strong contribution from -2 p transfer close to the Coulomb barrier, though this channel becomes less significant in relation to the -2 p 2 n transfer channel at larger separations. For 18O+208Pb , the -2 p 2 n channel is the dominant charge transfer mode at all separations. In the reactions with 19F,-3 p 2 n transfer is significant close to the barrier, but falls off rapidly with energy. Multinucleon transfer processes are shown to lead to high excitation energies (up to ˜15 MeV), which is distinct from single nucleon transfer modes which predominantly populate states at low excitation energy. Conclusions: Kinetic energy is transferred into internal excitations following transfer, with this

  5. Study of the metabolism of flucytosine in Aspergillus species by sup 19 F nuclear magnetic resonance spectroscopy

    SciTech Connect

    Chouini-Lalanne, N.; Malet-Martino, M.C.; Martino, R.; Michel, G. )

    1989-11-01

    The metabolism of flucytosine (5FC) in two Aspergillus species (Aspergillus fumigatus and A. niger) was investigated by 19F nuclear magnetic resonance spectroscopy. In intact mycelia, 5FC was found to be deaminated to 5-fluorouracil and then transformed into fluoronucleotides; the catabolite alpha-fluoro-beta-alanine was also detected in A. fumigatus. Neither 5-fluoroorotic acid nor 5-fluoro-2'-deoxyuridine-5'-monophosphate was detected in perchloric acid extracts after any incubation with 5FC. 5FC, 5-fluorouracil, and the classical fluoronucleotides 5-fluorouridine-5'-mono-, di-, and triphosphates were identified in the acid-soluble pool. Two hydrolysis products of 5-fluorouracil incorporated into RNA, 5-fluorouridine-2'-monophosphate and 5-fluorouridine-3'-monophosphate, were found in the acid-insoluble pool. No significant differences in the metabolic transformation of 5FC were noted in the two species of Aspergillus. The main pathway of 5FC metabolism in the two species of Aspergillus studied is thus the biotransformation into ribofluoronucleotides and the subsequent incorporation of 5-fluorouridine-5'-triphosphate into RNA.

  6. A Miniaturized, 1.9F Integrated Optical Fiber and Stone Basket for Use in Thulium Fiber Laser Lithotripsy.

    PubMed

    Wilson, Christopher R; Hutchens, Thomas C; Hardy, Luke A; Irby, Pierce B; Fried, Nathaniel M

    2015-10-01

    The thulium fiber laser (TFL) is being explored as an alternative laser lithotripter to the standard holmium:yttrium-aluminum-garnet laser. The more uniform beam profile of the TFL enables higher power transmission through smaller fibers. In this study, a 100-μm core, 140-μm outer-diameter (OD) silica fiber with 5-mm length hollow steel tip was integrated with 1.3F (0.433-mm OD) nitinol wire basket to form a 1.9F (0.633-mm OD) device. TFL energy of 30 mJ, 500 μs pulse duration, and 500 Hz pulse rate was delivered to human uric acid stones, ex vivo. Stone ablation rates measured 1.5 ± 0.2 mg/s, comparable to 1.7 ± 0.3 mg/s using bare fiber tips separately with stone basket. With further development, this device may minimize stone retropulsion, allowing more efficient TFL lithotripsy at higher pulse rates. It may also provide increased flexibility, higher saline irrigation rates through the ureteroscope working channel, reduce fiber degradation compared with separate fiber and basket manipulation, and reduce laser-induced nitinol wire damage. PMID:26167738

  7. Modulation of the antioxidant activity of HO* scavengers by albumin binding: a 19F-NMR study.

    PubMed

    Aime, Silvio; Digilio, Giuseppe; Bruno, Erik; Mainero, Valentina; Baroni, Simona; Fasano, Mauro

    2003-08-01

    The interaction between different HO(z.rad;) radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF(3)PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF(3)PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF(3)PAF from HO* radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF(3)PAF and trolox were found to bind to BSA with association constants in the order of 5 x 10(3)M(-1) and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF(3)PAF. PMID:12878205

  8. Tumour oxygen dynamics measured simultaneously by near-infrared spectroscopy and 19F magnetic resonance imaging in rats.

    PubMed

    Xia, Mengna; Kodibagkar, Vikram; Liu, Hanli; Mason, Ralph P

    2006-01-01

    Simultaneous near-infrared spectroscopy (NIRS) and magnetic resonance imaging (MRI) were used to investigate the correlation between tumour vascular oxygenation and tissue oxygen tension dynamics in rat breast 13762NF tumours with respect to hyperoxic gas breathing. NIRS directly detected global variations in the oxygenated haemoglobin concentration (Delta[HbO(2)]) within tumours and oxygen tension (pO(2)) maps were achieved using (19)F MRI of the reporter molecule hexafluorobenzene. Multiple correlations were examined between rates and magnitudes of vascular (Delta[HbO(2)]) and tissue (pO(2)) responses. Significant correlations were found between response to oxygen and carbogen breathing using either modality. Comparison of results for the two methods showed a correlation between the vascular perfusion rate ratio and the mean pO(2) values (R(2) > 0.7). The initial rates of increase of Delta[HbO(2)] and the slope of dynamic pO(2) response, d(pO(2))/dt, of well-oxygenated voxels in response to hyperoxic challenge were also correlated. These results demonstrate the feasibility of simultaneous measurements using NIRS and MRI. As expected, the rate of pO(2) response to oxygen is primarily dependent upon the well perfused rather than poorly perfused vasculature. PMID:16357430

  9. Fission-fragment angular distributions for the 19F + 208Pb near- and sub-barrier fusion-fission reaction

    NASA Astrophysics Data System (ADS)

    Huanqiao, Zhang; Zuhua, Liu; Jincheng, Xu; Kan, Xu; Jun, Lu; Ming, Ruan

    1990-06-01

    Fission cross sections and angular distributions have been measured for the 19F + 208Pb reaction at bombarding energies from 83 to 105 MeV. The fission excitation function is well reproduced on the basis of the coupled-channels theory. The fission-fragment angular distributions are calculated in terms of the transition-state theory, with the transmission coefficients extracted from the excitation function calculation. It is found that a discrepancy between the observations and the predictions in angular anisotropy of fission fragments exists at near- and sub-barrier energies, except for lower and higher energy regions where the discrepancy tends to disappear. Moreover, the anisotropies as a function of the center-of-mass energy show a shoulder around 82 MeV. Our results clearly indicate the considerable effects of the coupling on the sub-barrier fusion cross section and on the near-barrier compound-nucleus spin distribution, and confirm the prediction of an approximately constant value for the mean square spin of a compound nucleus produced in a far sub-barrier fusion reaction.

  10. (19)F spin-lattice relaxation of perfluoropolyethers: Dependence on temperature and magnetic field strength (7.0-14.1T).

    PubMed

    Kadayakkara, Deepak K; Damodaran, Krishnan; Hitchens, T Kevin; Bulte, Jeff W M; Ahrens, Eric T

    2014-05-01

    Fluorine ((19)F) MRI of perfluorocarbon-labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for (19)F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of (19)F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated the R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1T) and at temperatures ranging from 256-323K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc<1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new (19)F MRI agents and methods is discussed. PMID:24594752

  11. 19F Spin-lattice Relaxation of Perfluoropolyethers: Dependence on Temperature and Magnetic Field Strength (7.0-14.1T)

    PubMed Central

    Kadayakkara, Deepak K.; Damodaran, Krishnan; Hitchens, T. Kevin; Bulte, Jeff W.M.; Ahrens, Eric T.

    2014-01-01

    Fluorine (19F) MRI of perfluorocarbon labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for 19F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of 19F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1 T) and at temperatures ranging from 256-323K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc < 1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new 19F MRI agents and methods is discussed. PMID:24594752

  12. Precision spectroscopy of the {sup 207}Pb{sup 19}F molecule: Implications for measurement of P-odd and T-odd effects

    SciTech Connect

    Alphei, Lukas D.; Grabow, Jens-Uwe; Petrov, A. N.; Mawhorter, Richard; Murphy, Benjamin; Baum, Alexander; Sears, Trevor J.; Yang, T. Zh.; Rupasinghe, P. M.; McRaven, C. P.; Shafer-Ray, N. E.

    2011-04-15

    Here we report precision microwave spectroscopy of pure rotational transitions of the {sup 207}Pb{sup 19}F isotopologue. We use these data to make predictions of the sensitivity of the molecule to P-odd, T-even and P-odd, T-odd effects.

  13. (1)H and (19)F spin-lattice relaxation and CH3 or CF3 reorientation in molecular solids containing both H and F atoms.

    PubMed

    Beckmann, Peter A; Rheingold, Arnold L

    2016-04-21

    The dynamics of methyl (CH3) and fluoromethyl (CF3) groups in organic molecular (van der Waals) solids can be exploited to survey their local environments. We report solid state (1)H and (19)F spin-lattice relaxationexperiments in polycrystalline 3-trifluoromethoxycinnamic acid, along with an X-ray diffraction determination of the molecular and crystal structure, to investigate the intramolecular and intermolecular interactions that determine the properties that characterize the CF3 reorientation. The molecule is of no particular interest; it simply provides a motionless backbone (on the nuclear magnetic resonance(NMR) time scale) to investigate CF3 reorientation occurring on the NMR time scale. The effects of (19)F-(19)F and (19)F-(1)H spin-spin dipolar interactions on the complicated nonexponential NMRrelaxation provide independent inputs into determining a model for CF3 reorientation. As such, these experiments provide much more information than when only one spin species (usually (1)H) is present. In Sec. IV, which can be read immediately after the Introduction without reading the rest of the paper, we compare the barrier to CH3 and CF3 reorientation in seven organic solids and separate this barrier into intramolecular and intermolecular components. PMID:27389221

  14. 1H and 19F spin-lattice relaxation and CH3 or CF3 reorientation in molecular solids containing both H and F atoms

    NASA Astrophysics Data System (ADS)

    Beckmann, Peter A.; Rheingold, Arnold L.

    2016-04-01

    The dynamics of methyl (CH3) and fluoromethyl (CF3) groups in organic molecular (van der Waals) solids can be exploited to survey their local environments. We report solid state 1H and 19F spin-lattice relaxation experiments in polycrystalline 3-trifluoromethoxycinnamic acid, along with an X-ray diffraction determination of the molecular and crystal structure, to investigate the intramolecular and intermolecular interactions that determine the properties that characterize the CF3 reorientation. The molecule is of no particular interest; it simply provides a motionless backbone (on the nuclear magnetic resonance (NMR) time scale) to investigate CF3 reorientation occurring on the NMR time scale. The effects of 19F-19F and 19F-1H spin-spin dipolar interactions on the complicated nonexponential NMR relaxation provide independent inputs into determining a model for CF3 reorientation. As such, these experiments provide much more information than when only one spin species (usually 1H) is present. In Sec. IV, which can be read immediately after the Introduction without reading the rest of the paper, we compare the barrier to CH3 and CF3 reorientation in seven organic solids and separate this barrier into intramolecular and intermolecular components.

  15. 19F spin-lattice relaxation of perfluoropolyethers: Dependence on temperature and magnetic field strength (7.0-14.1 T)

    NASA Astrophysics Data System (ADS)

    Kadayakkara, Deepak K.; Damodaran, Krishnan; Hitchens, T. Kevin; Bulte, Jeff W. M.; Ahrens, Eric T.

    2014-05-01

    Fluorine (19F) MRI of perfluorocarbon-labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for 19F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of 19F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated the R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1 T) and at temperatures ranging from 256-323 K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc < 1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new 19F MRI agents and methods is discussed.

  16. Direct mapping of 19F in 19FDG-6P in brain tissue at subcellular resolution using soft X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Poitry-Yamate, C.; Gianoncelli, A.; Kourousias, G.; Kaulich, B.; Lepore, M.; Gruetter, R.; Kiskinova, M.

    2013-10-01

    Low energy x-ray fluorescence (LEXRF) detection was optimized for imaging cerebral glucose metabolism by mapping the fluorine LEXRF signal of 19F in 19FDG, trapped as intracellular 19F-deoxyglucose-6-phosphate (19FDG-6P) at 1μm spatial resolution from 3μm thick brain slices. 19FDG metabolism was evaluated in brain structures closely resembling the general cerebral cytoarchitecture following formalin fixation of brain slices and their inclusion in an epon matrix. 2-dimensional distribution maps of 19FDG-6P were placed in a cytoarchitectural and morphological context by simultaneous LEXRF mapping of N and O, and scanning transmission x-ray (STXM) imaging. A disproportionately high uptake and metabolism of glucose was found in neuropil relative to intracellular domains of the cell body of hypothalamic neurons, showing directly that neurons, like glial cells, also metabolize glucose. As 19F-deoxyglucose-6P is structurally identical to 18F-deoxyglucose-6P, LEXRF of subcellular 19F provides a link to in vivo 18FDG PET, forming a novel basis for understanding the physiological mechanisms underlying the 18FDG PET image, and the contribution of neurons and glia to the PET signal.

  17. On the Magic Square and Inverse

    ERIC Educational Resources Information Center

    Elzaidi, S. M.

    2005-01-01

    In this note, we give a method for finding the inverse of a three by three magic square matrix without using the usual methods for finding the inverse of a matrix. Also we give a method for finding the inverse of a three by three magic square matrix whose entries are also matrices. By using these ideas, we can construct large matrices whose…

  18. The Role of Statistics in Management Magic

    ERIC Educational Resources Information Center

    Stivers, Richard

    2004-01-01

    Technology and magic both represent the human will to power - to dominate nature and ultimately humans. In a technological civilization, magic imitates technology. Modern management often entails psychological techniques (the human relations approach) and organizational techniques (the scientific approach). The heart of the latter is statistical…

  19. Algebra Magic Tricks: Algecadabra! Volume 1.

    ERIC Educational Resources Information Center

    Edwards, Ronald

    This resource book contains 20 magic tricks based on the properties of whole numbers that are intended to spark the interest and imagination of students. Following each activity, students are asked to write about their discoveries and to create their own magic tricks. A matrix of skills for all the activities and lists of the materials required…

  20. Algebra Magic Tricks: Algecadabra! Volume 2.

    ERIC Educational Resources Information Center

    Edwards, Ronald

    This resource book contains 15 magic tricks based on the properties of whole numbers that are intended to spark the interest and imagination of students. Following each activity, students are asked to write about their discoveries and to create their own magic tricks. A matrix of skills for all the activities and lists of the materials required…

  1. Using Magic Words to Teach Social Studies.

    ERIC Educational Resources Information Center

    Barton, Keith C.

    1996-01-01

    Presents a lesson plan that uses subordinating conjunctions and prepositions as "magic words." After a lesson or unit of study, students write content specific sentences using the "magic" conjunctions and prepositions. This activity serves as a unit review, helps with concept formation, and increases writing skills. (MJP)

  2. Calculation of vibrational branching ratios and hyperfine structure of 24Mg19F and its suitability for laser cooling and magneto-optical trapping

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping

    2016-01-01

    More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.

  3. The magic of social thought.

    PubMed

    Kalampalikis, Nikos

    2014-10-01

    Studying social thinking provides a promising field of investigation for the constitution of common knowledge in communication and action of historically and culturally situated groups. Its genealogy helps the understanding of the symbolic efficacy of social practices and their own operating collective logic. The English translation of a short version of Serge Moscovici's article on the new magical thinking allows a wider audience to gain access, for the first time, to a text that perfectly illustrates the currentness and relevance of the social psychology of knowledge. PMID:25288162

  4. On the Power of Reusable Magic States

    NASA Astrophysics Data System (ADS)

    Anderson, Jonas

    2013-03-01

    In this paper we study reusable magic states. These states are a subset of the standard magic states. Once distilled, reusable magic states can be used repeatedly to apply some unitary U. Given this property, reusable magic states have the potential to greatly lower qubit and gate overhead in fault-tolerant quantum computation. While these states have some potential for lowering overhead, we provide a strong argument for their limited computational power. Specifically, we show that if reusable magic states can be used to apply non-Clifford unitaries, then we can exploit them to efficiently simulate poly-sized quantum circuits on a classical computer. JTA was supported in part by the National Science Foundation through Grant 0829944. JTA was supported in part by the Laboratory Directed Research and Development program at Sandia National Laboratories.

  5. Characterisation and evaluation of paramagnetic fluorine labelled glycol chitosan conjugates for (19)F and (1)H magnetic resonance imaging.

    PubMed

    De Luca, Elena; Harvey, Peter; Chalmers, Kirsten H; Mishra, Anurag; Senanayake, P Kanthi; Wilson, J Ian; Botta, Mauro; Fekete, Marianna; Blamire, Andrew M; Parker, David

    2014-02-01

    Medium molecular weight glycol chitosan conjugates have been prepared, linked by an amide bond to paramagnetic Gd(III), Ho(III) and Dy(III) macrocyclic complexes in which a trifluoromethyl reporter group is located 6.5 Å from the paramagnetic centre. The faster relaxation of the observed nucleus allows modified pulse sequences to be used with shorter acquisition times. The polydisperse materials have been characterised by gel permeation chromatography, revealing an average molecular weight on the order of 13,800 (Gd), 14,600 (Dy) and 16,200 (Ho), consistent with the presence of 8.5, 9.5 and 13 complexes, respectively. The gadolinium conjugate was prepared for both a q = 1 monoamide tricarboxylate conjugate (r1p 11.2 mM(-1) s(-1), 310 K, 1.4 T) and a q = 0 triphosphinate system, and conventional contrast-enhanced proton MRI studies at 7 T were undertaken in mice bearing an HT-29 or an HCT-116 colorectal tumour xenograft (17 μmol/kg). Enhanced contrast was observed following injection in the tail vein in tumour tissue, with uptake also evident in the liver and kidney with a tumour-to-liver ratio of 2:1 at 13 min, and large amounts in the kidney and bladder consistent with predominant renal clearance. Parallel experiments observing the (19)F resonance in the holmium conjugate complex using a surface coil did not succeed owing to its high R2 value (750 Hz, 7 T). However, the fluorine signal in the dysprosium triphosphinate chitosan conjugate [R1/R2 = 0.6 and R1 = 145 Hz (7 T)] was sharper and could be observed in vivo at -65.7 ppm, following intravenous tail vein injection of a dose of 34 μmol/kg. PMID:23955558

  6. Evaluation of tumor ischemia in response to an indole-based vascular disrupting agent using BLI and (19)F MRI.

    PubMed

    Zhou, Heling; Hallac, Rami R; Lopez, Ramona; Denney, Rebecca; MacDonough, Matthew T; Li, Li; Liu, Li; Graves, Edward E; Trawick, Mary Lynn; Pinney, Kevin G; Mason, Ralph P

    2015-01-01

    Vascular disrupting agents (VDAs) have been proposed as an effective broad spectrum approach to cancer therapy, by inducing ischemia leading to hypoxia and cell death. A novel VDA (OXi8007) was recently reported to show rapid acute selective shutdown of tumor vasculature based on color-Doppler ultrasound. We have now expanded investigations to noninvasively assess perfusion and hypoxiation of orthotopic human MDA-MB-231/luc breast tumor xenografts following the administration of OXi8007 based on dynamic bioluminescence imaging (BLI) and magnetic resonance imaging (MRI). BLI showed significantly lower signal four hours after the administration of OXi8007, which was very similar to the response to combretastatin A-4P (CA4P), but the effect lasted considerably longer, with the BLI signal remaining depressed at 72 hrs. Meanwhile, control tumors exhibited minimal change. Oximetry used (19)F MRI of the reporter molecule hexafluorobenzene and FREDOM (Fluorocarbon Relaxometry using Echo Planar Imaging for Dynamic Oxygen Mapping) to assess pO2 distributions during air and oxygen breathing. pO2 decreased significantly upon the administration of OXi8007 during oxygen breathing (from 122 ± 64 to 34 ± 20 Torr), with further decrease upon switching the gas to air (pO2 = 17 ± 9 Torr). pO2 maps indicated intra-tumor heterogeneity in response to OXi8007, though ultimately all tumor regions became hypoxic. Both BLI and FREDOM showed the efficacy of OXi8007. The pO2 changes measured by FREDOM may be crucial for future study of combined therapy. PMID:25973335

  7. 1H and 19F NMR studies on molecular motions and phase transitions in solid triethylammonium tetrafluoroborate

    NASA Astrophysics Data System (ADS)

    Ono, Hiroshi; Seki, Riki; Ikeda, Ryuichi; Ishida, Hiroyuki

    1995-02-01

    Measurements by differential thermal analysis and differential scanning calorimetry and of the spin-lattice relaxation time ( T1), the spin-spin relaxation time ( T2), and the second moment ( M2) of 1H and 19F NMR were carried out in the three solid phases of (CH 3CH 2) 3NHBF 4. X-ray powder patterns were taken in the highest-temperature phase (Phase I) existing above 367 K and the room-temperature phase (Phase II) stable between 220 and 367 K. Phase I formed a NaCl-type cubic structure with a = 11.65(3) Å, Z = 4, V = 1581(13) Å3, and Dx = 0.794 g cm -3, and was expected to be an ionic plastic phase. In this phase, the self-diffusion of anions and the isotropic reorientation of cations were observed. Phase II formed a tetragonal structure with a = 12.47(1) and c = 9.47(3) Å, Z = 4, V = 1473(6) Å3, and Dx = 0.852 g cm -3. From the present DSC and NMR results in this phase, the cations and/or anions were considered to be dynamically disordered states. The C3 reorientation of the cation about the NH bond axis was detected and, in addition, the onset of nutation of the cations and local diffusion of the anions was suggested. In the low-temperature phase (Phase III) stable below 219 K, the C3 reorientations of the three methyl groups of cations and the isotropic reorientation of anions were observed. The motional parameters for these modes were evaluated.

  8. Evidence for the importance of 5'-deoxy-5-fluorouridine catabolism in humans from 19F nuclear magnetic resonance spectrometry.

    PubMed

    Malet-Martino, M C; Armand, J P; Lopez, A; Bernadou, J; Béteille, J P; Bon, M; Martino, R

    1986-04-01

    The use of a new methodology, 19F nuclear magnetic resonance, has allowed detection of all the fluorinated metabolites in the biofluids of patients treated with 5'-deoxy-5-fluorouridine (5'-dFUrd) injected i.v. at a dose of 10 g/m2 over 6 h. This technique, which requires no labeled drug, allows a direct study of the biological sample with no need for extraction or derivatization and a simultaneous identification and quantitation of all the different fluorinated metabolites. As well as the already known metabolites, unmetabolized 5'-dFUrd, 5-fluorouracil, and 5,6-dihydro-5-fluorouracil, the presence of alpha-fluoro-beta-ureidopropionic acid, alpha-fluoro-beta-alanine (FBAL), N-carboxy-alpha-fluoro-beta-alanine, and the fluoride anion F- is reported. The catabolic pathway proposed for 5'-dFUrd is analogous to that of 5-fluorouracil, completed with FBAL----F- step, and the plasmatic equilibrium of FBAL with N-carboxy-alpha-fluoro-beta-alanine, its N-carboxy derivative. The quantitative analysis of the different metabolites found in plasma and urine emphasizes the significance of the catabolic pathway. High concentrations of alpha-fluoro-beta ureidopropionic acid and FBAL are recovered in plasma from 3 h after the beginning of the perfusion to 1 h after its end. The global urinary excretion results show that there is a high excretion of 5'-dFUrd and metabolites. Unchanged 5'-dFUrd and FBAL are by far the major excretory products and are at nearly equal rates. The protocol followed in this study produces relatively low but persistent plasmatic concentrations of 5-fluorouracil throughout the perfusion. PMID:2936452

  9. Automated data evaluation and modelling of simultaneous (19) F-(1) H medium-resolution NMR spectra for online reaction monitoring.

    PubMed

    Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Paul, Andrea; Engel, Dirk; Guthausen, Gisela; Kraume, Matthias; Maiwald, Michael

    2016-06-01

    Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and process monitoring. In contrast to high-resolution online NMR (HR-NMR), MR-NMR can be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture from the reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by (1) H HR-NMR (500 MHz) and (1) H and (19) F MR-NMR (43 MHz) as a model system. The parallel online measurement is realised by splitting the flow, which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for (1) H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25854892

  10. pEffect of MRI tags: SPIO nanoparticles and 19F nanoemulsion on various populations of mouse mesenchymal stem cells

    PubMed Central

    Muhammad, Ghulam; Jablonska, Anna; Rose, Laura; Walczak, Piotr; Janowski, Miroslaw

    2016-01-01

    Transplantation of mesenchymal stem cells (MSCs) has emerged as a promising strategy for the treatment of myriad human disorders, including several neurological diseases. Superparamagnetic iron oxide nanoparticles (SPION) and fluorine nanoemulsion (19F) are characterized by low toxicity and good sensitivity, and, as such, are among the most frequently used cell-labeling agents. However, to date, their impact across the various populations of MSCs has not been comprehensively investigated. Thus, the impact of MRI tags (independent variable) has been set as a primary endpoint. The various populations of mouse MSCs in which the effect of tag was investigated consisted of 1) tissue of cell origin: bone marrow vs. adipose tissue; 2) age of donor: young vs. old; 3) cell culture conditions: hypoxic vs. normal vs. normal +ascorbic acid (AA); 4) exposure to acidosis: yes vs. no. The impact of those populations has been also analyzed and considered as secondary endpoints. The experimental readouts (dependent variables) included: 1) cell viability; 2) cell size; 3) cell doubling time; 4) colony formation; 5) efficiency of labeling; and 6) cell migration. We did not identify any impact of cell labeling for these investigated populations in any of the readouts. In addition, we found that the harsh microenvironment of injured tissue modeled by a culture of cells in a highly acidic environment has a profound effect on all readouts, and both age of donor and cell origin tissue also have a substantial influence on most of the readouts, while oxygen tension in the cell culture conditions has a smaller impact on MSCs. A detailed characterization of the factors that influence the quality of MSCs is vital to the proper pursuit of preclinical and clinical studies. PMID:26232992

  11. Alternate strategies to obtain mass balance without the use of radiolabeled compounds: application of quantitative fluorine (19F) nuclear magnetic resonance (NMR) spectroscopy in metabolism studies.

    PubMed

    Mutlib, Abdul; Espina, Robert; Atherton, James; Wang, Jianyao; Talaat, Rasmy; Scatina, JoAnn; Chandrasekaran, Appavu

    2012-03-19

    Nuclear magnetic resonance (NMR) spectroscopy is playing an increasingly important role in the quantitation of small and large molecules. Recently, we demonstrated that (1)H NMR could be used to quantitate drug metabolites isolated in submilligram quantities from biological sources. It was shown that these metabolites, once quantitated by NMR, were suitable to be used as reference standards in quantitative LC/MS-based assays, hence circumventing the need for radiolabeled material or synthetic standards to obtain plasma exposure estimates in humans and preclinical species. The quantitative capabilities of high-field NMR is further demonstrated in the current study by obtaining the mass balance of fluorinated compounds using (19)F-NMR. Two fluorinated compounds which were radio-labeled with carbon-14 on metabolically stable positions were dosed in rats and urine and feces collected. The mass balance of the compounds was obtained initially by counting the radioactivity present in each sample. Subsequently, the same sets of samples were analyzed by (19)F-NMR, and the concentrations determined by this method were compared with data obtained using radioactivity counting. It was shown that the two methods produced comparable values. To demonstrate the value of this analytical technique in drug discovery, a fluorinated compound was dosed intravenously in dogs and feces and urine collected. Initial profiling of samples showed that this compound was excreted mainly unchanged in feces, and hence, an estimate of mass balance was obtained using (19)F-NMR. The data obtained by this method was confirmed by additional quantitative studies using mass spectrometry. Hence cross-validations of the quantitative (19)F-NMR method by radioactivity counting and mass spectrometric analysis were demonstrated in this study. A strategy outlining the use of fluorinated compounds in conjunction with (19)F-NMR to understand their routes of excretion or mass balance in animals is proposed. These

  12. Magic wavelengths for terahertz clock transitions

    SciTech Connect

    Zhou Xiaoji; Xu Xia; Chen Xuzong; Chen Jingbiao

    2010-01-15

    Magic wavelengths for laser trapping of boson isotopes of alkaline-earth metal atoms Sr, Ca, and Mg are investigated while considering terahertz clock transitions between the {sup 3}P{sub 0}, {sup 3}P{sub 1}, and {sup 3}P{sub 2} metastable triplet states. Our calculation shows that magic wavelengths for laser trapping do exist. This result is important because those metastable states have already been used to make accurate clocks in the terahertz frequency domain. Detailed discussions for magic wavelengths for terahertz clock transitions are given in this article.

  13. γ-(S)-Trifluoromethyl proline: evaluation as a structural substitute of proline for solid state (19)F-NMR peptide studies.

    PubMed

    Kubyshkin, Vladimir; Afonin, Sergii; Kara, Sezgin; Budisa, Nediljko; Mykhailiuk, Pavel K; Ulrich, Anne S

    2015-03-21

    γ-(4S)-Trifluoromethyl proline was synthesised according to a modified literature protocol with improved yield on a multigram scale. Conformational properties of the amide bond formed by the amino acid were characterised using N-acetyl methyl ester model. The amide populations (s-trans vs. s-cis) and thermodynamic parameters of the isomerization were found to be similar to the corresponding values for intact proline. Therefore, the γ-trifluoromethyl proline was suggested as a structurally low-disturbing proline substitution in peptides for their structural studies by (19)F-NMR. Indeed, the exchange of native proline for γ-trifluoromethyl proline in the peptide antibiotic gramicidin S was shown to preserve the overall amphipathic peptide structure. The utility of the amino acid as a selective (19)F-NMR label was demonstrated by observing the re-alignment of the labelled gramicidin S in oriented lipid bilayers. PMID:25703116

  14. Angular momentum distribution for the formation of evaporation residues in fusion of 19F with 184W near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Nath, S.; Gehlot, J.; Prasad, E.; Sadhukhan, Jhilam; Shidling, P. D.; Madhavan, N.; Muralithar, S.; Golda, K. S.; Jhingan, A.; Varughese, T.; Rao, P. V. Madhusudhana; Sinha, A. K.; Pal, Santanu

    2011-01-01

    We present γ-ray multiplicity distributions for the formation of evaporation residues in the fusion reaction 19F + 184W → 20383Bi 120 at beam energies in the range of 90-110 MeV. The measurements were carried out using a 14 element BGO detector array and the Heavy Ion Reaction Analyzer at the Inter University Accelerator Centre. The data have been unfolded to obtain angular momentum distributions with inputs from the statistical model calculation. Comparison with another neighboring system, viz. 19F + 175Lu → 19480Hg 114 with nearly similar entrance-channel mass asymmetry, hints at the depletion of higher angular momenta after crossing of the Z=82 shell in the compound nucleus.

  15. The magic of relay mirrors

    NASA Astrophysics Data System (ADS)

    Duff, Edward A.; Washburn, Donald C.

    2004-09-01

    Laser weapon systems would be significantly enhanced with the addition of high altitude or space-borne relay mirrors. Such mirrors, operating alone with a directed energy source, or many in a series fashion, can be shown to effectively move the laser source to the last, so-called fighting mirror. This "magically" reduces the range to target and offers to enhance the performance of directed energy systems like the Airborne Laser and even ground-based or ship-based lasers. Recent development of high altitude airships will be shown to provide stationary positions for such relay mirrors thereby enabling many new and important applications for laser weapons. The technical challenges to achieve this capability are discussed.

  16. Insurance, risk, and magical thinking.

    PubMed

    Tykocinski, Orit E

    2008-10-01

    The possession of an insurance policy may not only affect the severity of a potential loss but also its perceived probability. Intuitively, people may feel that if they are insured nothing bad is likely to happen, but if they do not have insurance they are at greater peril. In Experiment 1, respondents who were reminded of their medical insurance felt they were less likely to suffer health problems in the future compared to people who were not reminded of their medical insurance. In Experiment 2a, participants who were unable to purchase travel insurance judged the probability of travel-related calamities higher compared to those who were insured. These results were replicated in Experiment 3a in a simulation of car accident insurance. The findings are explained in terms of intuitive magical thinking, specifically, the negative affective consequences of "tempting fate" and the sense of safety afforded by the notion of "being covered." PMID:18612038

  17. On magic numbers for super- and ultraheavy systems and hypothetical spherical double-magic nuclei

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Ellithi, A. Y.; Adel, A.; Anwer, Hisham

    2016-01-01

    Based on the calculations of the shell and the residual pairing correction energies in the framework of Strutinsky's approach, we evaluated the proton and neutron magic numbers in the range 72 ≤ Z ≤ 282 and 96 ≤ N ≤ 540. New magic numbers and new islands of stability lie in a range defined by Green's formula and the two-neutrons drip lines are presented. Our calculations reproduced known spherical double-magic nuclei and present evidences on new spherical double-magic nuclei in super- and ultraheavy regions.

  18. Design principles and theory of paramagnetic fluorine-labelled lanthanide complexes as probes for (19)F magnetic resonance: a proof-of-concept study.

    PubMed

    Chalmers, Kirsten H; De Luca, Elena; Hogg, Naomi H M; Kenwright, Alan M; Kuprov, Ilya; Parker, David; Botta, Mauro; Wilson, J Ian; Blamire, Andrew M

    2010-01-01

    The synthesis and spectroscopic properties of a series of CF(3)-labelled lanthanide(III) complexes (Ln=Gd, Tb, Dy, Ho, Er, Tm) with amide-substituted ligands based on 1,4,7,10-tetraazacyclododecane are described. The theoretical contributions of the (19)F magnetic relaxation processes in these systems are critically assessed and selected volumetric plots are presented. These plots allow an accurate estimation of the increase in the rates of longitudinal and transverse relaxation as a function of the distance between the Ln(III) ion and the fluorine nucleus, the applied magnetic field, and the re-rotational correlation time of the complex, for a given Ln(III) ion. Selected complexes exhibit pH-dependent chemical shift behaviour, and a pK(a) of 7.0 was determined in one example based on the holmium complex of an ortho-cyano DO3A-monoamide ligand, which allowed the pH to be assessed by measuring the difference in chemical shift (varying by over 14 ppm) between two (19)F resonances. Relaxation analyses of variable-temperature and variable-field (19)F, (17)O and (1)H NMR spectroscopy experiments are reported, aided by identification of salient low-energy conformers by using density functional theory. The study of fluorine relaxation rates, over a field range of 4.7 to 16.5 T allowed precise computation of the distance between the Ln(III) ion and the CF(3) reporter group by using global fitting methods. The sensitivity benefits of using such paramagnetic fluorinated probes in (19)F NMR spectroscopic studies are quantified in preliminary spectroscopic and imaging experiments with respect to a diamagnetic yttrium(III) analogue. PMID:19957317

  19. High-resolution three-dimensional 19F-magnetic resonance imaging of rat lung in situ: evaluation of airway strain in the perfluorocarbon-filled lung.

    PubMed

    Weigel, Julia K; Steinmann, Daniel; Emerich, Philipp; Stahl, Claudius A; v Elverfeldt, Dominik; Guttmann, Josef

    2011-02-01

    Perfluorocarbons (PFC) are biologically and chemically inert fluids with high oxygen and CO(2) carrying capacities. Their use as liquid intrapulmonary gas carriers during liquid ventilation has been investigated. We established a method of high resolution 3D-(19)F-MRI of the totally PFC-filled lung. The goal of this study was to investigate longitudinal and circumferential airway strain in the setting of increasing airway pressures on 3D-(19)F-MR images of the PFC-filled lung. Sixteen female Wistar rats were euthanized and the liquid perfluorocarbon FC-84 instilled into their lungs. 3D-(19)F-MRI was performed at various intrapulmonary pressures. Measurements of bronchial length and cross-sectional area were obtained from transversal 2D images for each pressure range. Changes in bronchial area were used to determine circumferential strain, while longitudinal strain was calculated from changes in bronchial length. Our method of 3D-(19)F-MRI allowed clear visualization of the great bronchi. Longitudinal strain increased significantly up to 31.1 cmH(2)O. The greatest strain could be found in the range of low airway pressures. Circumferential strain increased strongly with the initial pressure rise, but showed no significant changes above 10.4 cmH(2)O. Longitudinal strain was generally higher in distal airways, while circumferential strain showed no difference. Analysis of mechanical characteristics showed that longitudinal and circumferential airway expansion occurred in an anisotropic fashion. Whereas longitudinal strain still increased with higher pressures, circumferential strain quickly reached a 'strain limit'. Longitudinal strain was higher in distal bronchi, as dense PFCs gravitate to dependent, in this case to dorso-basal parts of the lung, acting as liquid positive end expiratory pressure. PMID:21193813

  20. 19F Magnetic Resonance Imaging of Perfluorocarbons for the Evaluation of Response to Antibiotic Therapy in a Staphylococcus aureus Infection Model

    PubMed Central

    Jakob, Peter; Ohlsen, Knut

    2013-01-01

    Background The emergence of antibiotic resistant bacteria in recent decades has highlighted the importance of developing new drugs to treat infections. However, in addition to the design of new drugs, the development of accurate preclinical testing methods is essential. In vivo imaging technologies such as bioluminescence imaging (BLI) or magnetic resonance imaging (MRI) are promising approaches. In a previous study, we showed the effectiveness of 19F MRI using perfluorocarbon (PFC) emulsions for detecting the site of Staphylococcus aureus infection. In the present follow-up study, we investigated the use of this method for in vivo visualization of the effects of antibiotic therapy. Methods/Principal findings Mice were infected with S. aureus Xen29 and treated with 0.9% NaCl solution, vancomycin or linezolid. Mock treatment led to the highest bioluminescence values during infection followed by vancomycin treatment. Counting the number of colony-forming units (cfu) at 7 days post-infection (p.i.) showed the highest bacterial burden for the mock group and the lowest for the linezolid group. Administration of PFCs at day 2 p.i. led to the accumulation of 19F at the rim of the abscess in all mice (in the shape of a hollow sphere), and antibiotic treatment decreased the 19F signal intensity and volume. Linezolid showed the strongest effect. The BLI, cfu, and MRI results were comparable. Conclusions 19F-MRI with PFCs is an effective non-invasive method for assessing the effects of antibiotic therapy in vivo. This method does not depend on pathogen specific markers and can therefore be used to estimate the efficacy of antibacterial therapy against a broad range of clinically relevant pathogens, and to localize sites of infection. PMID:23724049

  1. What's Your Angle on Angles?

    ERIC Educational Resources Information Center

    Browning, Christine A.; Garza-Kling, Gina; Sundling, Elizabeth Hill

    2007-01-01

    Although the nature of the research varies, as do concepts of angle, research in general supports the supposition that angle is a complex idea, best understood from a variety of perspectives. In fact, the concept of angle tends to be threefold, consisting of: (1) the traditional, static notion of two rays meeting at a common vertex; (2) the idea…

  2. THE FLUORINE DESTRUCTION IN STARS: FIRST EXPERIMENTAL STUDY OF THE {sup 19}F(p, {alpha}{sub 0}){sup 16}O REACTION AT ASTROPHYSICAL ENERGIES

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Indelicato, I.; Cherubini, S.; Gulino, M.; Kiss, G. G.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Mukhamedzhanov, A. M.; Aliotta, M.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Piskor, S.; Coc, A.

    2011-10-01

    The {sup 19}F(p, {alpha}){sup 16}O reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. So far, available direct measurements do not reach the energy region of astrophysical interest (E {sub cm} {approx}< 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the {sup 2}H({sup 19}F, {alpha}{sup 16}O)n and the {sup 19}F({sup 3}He, {alpha}{sup 16}O)d reactions. The TH measurement of the {alpha}{sub 0} channel shows the presence of resonant structures not observed before, which cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential consequences for stellar nucleosynthesis.

  3. Completion of the Operational Closure of Tank 18F and Tank 19F at the Savannah River Site by Grouting - 13236

    SciTech Connect

    Tisler, Andrew J.

    2013-07-01

    Radioactive waste is stored in underground waste tanks at the Savannah River Site (SRS). The low-level fraction of the waste is immobilized in a grout waste form, and the high level fraction is disposed of in a glass waste form. Once the waste is removed, the tanks are prepared for closure. Operational closure of the tanks consists of filling with grout for the purpose of chemically stabilizing residual material, filling the tank void space for long-term structural stability, and discouraging future intrusion. Two of the old-style single-shell tanks at the SRS have received regulatory approval confirming waste removal had been completed, and have been stabilized with grout as part of completing operational closure and removal from service. Consistent with the regulatory framework, two types of grout were used for the filling of Tanks 18F and 19F. Reducing grout was used to fill the entire volume of Tanks 18F and 19F (bulk fill grout) and a more flowable grout was used to fill equipment that was left in the tank (equipment fill grout). The reducing grout was added to the tanks using portable grout pumps filled from concrete trucks, and delivered the grout through slick lines to the center riser of each tank. Filling of the two tanks has been completed, and all equipment has been filled. The final capping of riser penetrations brings the operation closure of Tanks 18F and 19F to completion. (authors)

  4. Pharmaceutical Applications of Relaxation Filter-Selective Signal Excitation Methods for (19)F Solid-State Nuclear Magnetic Resonance: Case Study With Atorvastatin in Dosage Formulation.

    PubMed

    Asada, Mamiko Nasu; Nemoto, Takayuki; Mimura, Hisashi

    2016-03-01

    We recently developed several new relaxation filter-selective signal excitation (RFS) methods for (13)C solid-state nuclear magnetic resonance (NMR) that allow (13)C signal extraction of the target components from pharmaceuticals. These methods were successful in not only qualification but also quantitation over the wide range of 5% to 100%. Here, we aimed to improve the sensitivity of these methods and initially applied them to (19)F solid-state NMR, on the basis that the fluorine atom is one of the most sensitive NMR-active nuclei. For testing, we selected atorvastatin calcium (ATC), an antilipid BCS class II drug that inhibits 3-hydroxy-3-methylglutaryl-coenzyme A reductase and is marketed in crystalline and amorphous forms. Tablets were obtained from 2 generic drug suppliers, and the ATC content occurred mainly as an amorphous form. Using the RFS method with (19)F solid-state NMR, we succeeded in qualifying trace amounts (less than 0.5% w/w level) of crystalline phase (Form I) of ATC in the tablets. RFS methods with (19)F solid-state NMR are practical and time efficient and can contribute not only to the study of pharmaceutical drugs, including those with small amounts of a highly potent active ingredient within a formulated product, but also to the study of fluoropolymers in material sciences. PMID:26886305

  5. Demystifying fluorine chemical shifts: electronic structure calculations address origins of seemingly anomalous (19)F-NMR spectra of fluorohistidine isomers and analogues.

    PubMed

    Kasireddy, Chandana; Bann, James G; Mitchell-Koch, Katie R

    2015-11-11

    Fluorine NMR spectroscopy is a powerful tool for studying biomolecular structure, dynamics, and ligand binding, yet the origins of (19)F chemical shifts are not well understood. Herein, we use electronic structure calculations to describe the changes in (19)F chemical shifts of 2F- and 4F-histidine/(5-methyl)-imidazole upon acid titration. While the protonation of the 2F species results in a deshielded chemical shift, protonation of the 4F isomer results in an opposite, shielded chemical shift. The deshielding of 2F-histidine/(5-methyl)-imidazole upon protonation can be rationalized by concomitant decreases in charge density on fluorine and a reduced dipole moment. These correlations do not hold for 4F-histidine/(5-methyl)-imidazole, however. Molecular orbital calculations reveal that for the 4F species, there are no lone pair electrons on the fluorine until protonation. Analysis of a series of 4F-imidazole analogues, all with delocalized fluorine electron density, indicates that the deshielding of (19)F chemical shifts through substituent effects correlates with increased C-F bond polarity. In summary, the delocalization of fluorine electrons in the neutral 4F species, with gain of a lone pair upon protonation may help explain the difficulty in developing a predictive framework for fluorine chemical shifts. Ideas debated by chemists over 40 years ago, regarding fluorine's complex electronic effects, are shown to have relevance for understanding and predicting fluorine NMR spectra. PMID:26524669

  6. 19F-decoupling of half-integer spin quadrupolar nuclei in solid-state NMR: application of frequency-swept decoupling methods.

    PubMed

    Chandran, C Vinod; Hempel, Günter; Bräuniger, Thomas

    2011-09-01

    In solid-state NMR studies of minerals and ion conductors, quadrupolar nuclei like (7)Li, (23)Na or (133)Cs are frequently situated in close proximity to fluorine, so that application of (19)F decoupling is beneficial for spectral resolution. Here, we compare the decoupling efficiency of various multi-pulse decoupling sequences by acquiring (19)F-decoupled (23)Na-NMR spectra of cryolite (Na(3)AlF(6)). Whereas the MAS spectrum is only marginally affected by application of (19)F decoupling, the 3Q-filtered (23)Na signal is very sensitive to it, as the de-phasing caused by the dipolar interaction between sodium and fluorine is three-fold magnified. Experimentally, we find that at moderate MAS speeds, the decoupling efficiencies of the frequency-swept decoupling schemes SW(f)-TPPM and SW(f)-SPINAL are significantly better than the conventional TPPM and SPINAL sequences. The frequency-swept sequences are therefore the methods of choice for efficient decoupling of quadrupolar nuclei with half-integer spin from fluorine. PMID:21856132

  7. [Magical and religious healing in Byzantium].

    PubMed

    Józsa, László

    2010-01-01

    Religious and magical ways of healing have been known and practiced since the very beginning of human history. In the present article, the Byzantine philosophical, cultural, historical and "methodological" aspects of this way of healing are discussed. The article outlines the development of magic healing in Byzantium from the 4th to the 15th century. During this period magical therapy included the cult of patron saints--listed by the author--and pleading for divine intervention as well. The activity of "anargyroi" and the use of magical objects and amulets is also discussed in detail. Exorcism was also a part of religious therapy both against psychical and somatical diseases. In early Christianity, and especially in Byzantium the devil or other demons were also supposed to cause various somatical or psychical illnesses by "intrusion" or "internalisation," i.e. by possession or obsession of their victims. PMID:21661260

  8. Clinching First Place: Calculating the Magic Number.

    ERIC Educational Resources Information Center

    Quinn, Robert J.

    2000-01-01

    Describes a lesson plan in which students apply their mathematical intuition to determine win-loss possibilities of teams in a sports league and develop a formula for calculating the magic number for clinching first place. (YDS)

  9. Recent Results from the MAGIC Telescope

    SciTech Connect

    Bock, Rudolf K.

    2005-02-21

    Some recent results are shown, obtained during the commissioning period of the MAGIC telescope. They demonstrate that the telescope is now approaching a performance level suitable for physics observations.

  10. Working wonders? investigating insight with magic tricks.

    PubMed

    Danek, Amory H; Fraps, Thomas; von Müller, Albrecht; Grothe, Benedikt; Ollinger, Michael

    2014-02-01

    We propose a new approach to differentiate between insight and noninsight problem solving, by introducing magic tricks as problem solving domain. We argue that magic tricks are ideally suited to investigate representational change, the key mechanism that yields sudden insight into the solution of a problem, because in order to gain insight into the magicians' secret method, observers must overcome implicit constraints and thus change their problem representation. In Experiment 1, 50 participants were exposed to 34 different magic tricks, asking them to find out how the trick was accomplished. Upon solving a trick, participants indicated if they had reached the solution either with or without insight. Insight was reported in 41.1% of solutions. The new task domain revealed differences in solution accuracy, time course and solution confidence with insight solutions being more likely to be true, reached earlier, and obtaining higher confidence ratings. In Experiment 2, we explored which role self-imposed constraints actually play in magic tricks. 62 participants were presented with 12 magic tricks. One group received verbal cues, providing solution relevant information without giving the solution away. The control group received no informative cue. Experiment 2 showed that participants' constraints were suggestible to verbal cues, resulting in higher solution rates. Thus, magic tricks provide more detailed information about the differences between insightful and noninsightful problem solving, and the underlying mechanisms that are necessary to have an insight. PMID:24300080

  11. Self-Assembly of Peptide Amphiphiles Designed as Imaging Probes for 19F and Relaxation-Enhanced 1H imaging

    NASA Astrophysics Data System (ADS)

    Preslar, Adam Truett

    This work incorporates whole-body imaging functionality into peptide amphiphile (PA) nanostructures used for regenerative medicine to facilitate magnetic resonance imaging (MRI). Two strategies were employed: 1. Conjugation of gadolinium chelates to peptide nanostructures to monitor biomaterial degradation in vivo with MRI and inductively-coupled plasma-mass spectroscopy (ICP-MS) 2. Synthesis of perfluorinated moiety-bearing peptide amphiphiles for 19F-MRI. The Gd(III) chelate gadoteridol was conjugated by copper-catalyzed "click" chemistry to a series of PAs known to form cylindrical nanostructures. By fitting nuclear magnetic resonance dispersion (NMRD) profiles to the Solomon-Bloembergen-Morgan (SBM) equations, it was observed that the water exchange parameter (tauM) depended on thermal annealing or calcium ion cross-linking. The sequence C16V 3A3E3G(Gd) exhibited an acceleration of nearly 100 ns after thermal annealing and calcium addition. These gadolinium-labeled PAs were used to track in vivo degradation of gels within the tibialis anterior muscle in a murine model. The half-life of biomaterial degradation was determined to be 13.5 days by inductively coupled plasma mass spectrometry (ICP-MS) of Gd(III). Gel implants could be monitored by MRI for eight days before the signal dispersed due to implant degradation and dilution. Additionally, nanostructures incorporating highly fluorinated domains were investigated for use as MRI contrast agents. Short, perfluoroalkyane tails of seven or eight carbon atoms in length were grafted to PA sequences containing a V2A2 beta-sheet forming sequence. The V2A2 sequence is known to drive 1D nanostructure assembly. It was found that the sequences C7F13V2A 2E2 and C7F13V2A 2K3 formed 1D assemblies in water which transition from ribbon-like to cylindrical shape as pH increases from 4.5 to 8.0. Ribbon-like nanostructures had reduced magnetic resonance signal by T 2 relaxation quenching, whereas their cylindrical counterparts

  12. The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barceló, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Bitossi, M.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Cecchi, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Corti, D.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; de Oña Wilhelmi, E.; Delgado Mendez, C.; Dettlaff, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Fidalgo, D.; Fink, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Haberer, W.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Illa, J. M.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lemus, J. L.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Lorca, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Negrello, M.; Neustroev, V.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Noda, K.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schlammer, J.; Schmidl, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamerra, A.; Steinbring, T.; Storz, J.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Tejedor, L. A.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Wetteskind, H.; Will, M.; Zanin, R.

    2016-01-01

    MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ∼ 50 GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220 GeV is (0.66 ± 0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the σ of a 2-dimensional Gaussian distribution, at those energies is ≲ 0.07°, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11%-18% in flux normalization and ± 0.15 for the energy spectrum power-law slope.

  13. Entropy and the Magic Flute

    NASA Astrophysics Data System (ADS)

    Morowitz, Harold J.

    1996-10-01

    Harold Morowitz has long been highly regarded both as an eminent scientist and as an accomplished science writer. The essays in The Wine of Life , his first collection, were hailed by C.P. Snow as "some of the wisest, wittiest and best informed I have ever read," and Carl Sagan called them "a delight to read." In later volumes he established a reputation for a wide-ranging intellect, an ability to see unexpected connections and draw striking parallels, and a talent for communicating scientific ideas with optimism and wit. With Entropy and the Magic Flute , Morowitz once again offers an appealing mix of brief reflections on everything from litmus paper to the hippopotamus to the sociology of Palo Alto coffee shops. Many of these pieces are appreciations of scientists that Morowitz holds in high regard, while others focus on health issues, such as America's obsession with cheese toppings. There is also a fascinating piece on the American Type Culture Collection, a zoo or warehouse for microbes that houses some 11,800 strains of bacteria, and over 3,000 specimens of protozoa, algae, plasmids, and oncogenes. Here then are over forty light, graceful essays in which one of our wisest experimental biologists comments on issues of science, technology, society, philosophy, and the arts.

  14. The Magnetics Information Consortium (MagIC)

    NASA Astrophysics Data System (ADS)

    Johnson, C.; Constable, C.; Tauxe, L.; Koppers, A.; Banerjee, S.; Jackson, M.; Solheid, P.

    2003-12-01

    The Magnetics Information Consortium (MagIC) is a multi-user facility to establish and maintain a state-of-the-art relational database and digital archive for rock and paleomagnetic data. The goal of MagIC is to make such data generally available and to provide an information technology infrastructure for these and other research-oriented databases run by the international community. As its name implies, MagIC will not be restricted to paleomagnetic or rock magnetic data only, although MagIC will focus on these kinds of information during its setup phase. MagIC will be hosted under EarthRef.org at http://earthref.org/MAGIC/ where two "integrated" web portals will be developed, one for paleomagnetism (currently functional as a prototype that can be explored via the http://earthref.org/databases/PMAG/ link) and one for rock magnetism. The MagIC database will store all measurements and their derived properties for studies of paleomagnetic directions (inclination, declination) and their intensities, and for rock magnetic experiments (hysteresis, remanence, susceptibility, anisotropy). Ultimately, this database will allow researchers to study "on the internet" and to download important data sets that display paleo-secular variations in the intensity of the Earth's magnetic field over geological time, or that display magnetic data in typical Zijderveld, hysteresis/FORC and various magnetization/remanence diagrams. The MagIC database is completely integrated in the EarthRef.org relational database structure and thus benefits significantly from already-existing common database components, such as the EarthRef Reference Database (ERR) and Address Book (ERAB). The ERR allows researchers to find complete sets of literature resources as used in GERM (Geochemical Earth Reference Model), REM (Reference Earth Model) and MagIC. The ERAB contains addresses for all contributors to the EarthRef.org databases, and also for those who participated in data collection, archiving and

  15. Magnetic properties and hyperfine interactions in Cr8, Cr7Cd, and Cr7Ni molecular rings from 19F-NMR

    SciTech Connect

    Bordonali, L; Garlatti, E; Casadei, C M; Furukawa, Y; Lascialfari, A; Carretta, S; Troiani, F; Timco, G; Winpenny, R E; Borsa, F

    2014-04-14

    A detailed experimental investigation of the 19F nuclear magnetic resonance is made on single crystals of the homometallic Cr₈ antiferromagnetic molecular ring and heterometallic Cr₇Cd and Cr₇ Ni rings in the low temperature ground state. Since the F- ion is located midway between neighboring magnetic metal ions in the ring, the 19F-NMR spectra yield information about the local electronic spin density and ¹⁹F hyperfine interactions. In Cr8, where the ground state is a singlet with total spin S T = 0, the ¹⁹F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the ¹⁹F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S T = 1. In the heterometallic rings, Cr₇Cd and Cr₇ Ni, whose ground state is magnetic with S T = 3/2 and S T = 1/2, respectively, the ¹⁹F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the 19F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F⁻-Ni2⁺ and the F⁻-Cd2⁺ bonds. The values of the hyperfine constants compare well to the ones known for F⁻-Ni2⁺ in KNiF₃ and NiF₂ and for F⁻-Cr³⁺ in K₂NaCrF₆. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F⁻ ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

  16. Updated THM Astrophysical Factor of the 19F(p, α)16O Reaction and Influence of New Direct Data at Astrophysical Energies

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Palmerini, S.; Spitaleri, C.; Indelicato, I.; Mukhamedzhanov, A. M.; Lombardo, I.; Trippella, O.

    2015-06-01

    Fluorine nucleosynthesis represents one of the most intriguing open questions in nuclear astrophysics. It has triggered new measurements which may modify the presently accepted paradigm of fluorine production and establish fluorine as an accurate probe of the inner layers of asymptotic giant branch (AGB) stars. Both direct and indirect measurements have attempted to improve the recommended extrapolation to astrophysical energies, showing no resonances. In this work, we will demonstrate that the interplay between direct and indirect techniques represents the most suitable approach to attain the required accuracy for the astrophysical factor at low energies, {{E}c.m.}≲ 300 keV, which is of interest for fluorine nucleosynthesis in AGB stars. We will use the recently measured direct 19F{{(p,α )}16}O astrophysical factor in the 600 keV≲ {{E}c.m.}≲ 800 keV energy interval to renormalize the existing Trojan Horse Method (THM) data spanning the astrophysical energies, accounting for all identified sources of uncertainty. This has a twofold impact on nuclear astrophysics. It shows the robustness of the THM approach even in the case of direct data of questionable quality, as normalization is extended over a broad range, minimizing systematic effects. Moreover, it allows us to obtain more accurate resonance data at astrophysical energies, thanks to the improved 19F{{(p,α )}16}O direct data. Finally, the present work strongly calls for more accurate direct data at low energies, so that we can obtain a better fitting of the direct reaction mechanism contributing to the 19F{{(p,α )}16}O astrophysical factor. Indeed, this work points out that the major source of uncertainty affecting the low-energy S(E) factor is the estimate of the non-resonant contribution, as the dominant role of the 113 keV resonance is now well established.

  17. 19F Nuclear Magnetic Resonance and Crystallographic Studies of 5-Fluorotryptophan-Labeled Anthrax Protective Antigen and Effects of the Receptor on Stability

    PubMed Central

    2015-01-01

    The anthrax protective antigen (PA) is an 83 kDa protein that is one of three protein components of the anthrax toxin, an AB toxin secreted by Bacillus anthracis. PA is capable of undergoing several structural changes, including oligomerization to either a heptameric or octameric structure called the prepore, and at acidic pH a major conformational change to form a membrane-spanning pore. To follow these structural changes at a residue-specific level, we have conducted initial studies in which we have biosynthetically incorporated 5-fluorotryptophan (5-FTrp) into PA, and we have studied the influence of 5-FTrp labeling on the structural stability of PA and on binding to the host receptor capillary morphogenesis protein 2 (CMG2) using 19F nuclear magnetic resonance (NMR). There are seven tryptophans in PA, but of the four domains in PA, only two contain tryptophans: domain 1 (Trp65, -90, -136, -206, and -226) and domain 2 (Trp346 and -477). Trp346 is of particular interest because of its proximity to the CMG2 binding interface, and because it forms part of the membrane-spanning pore. We show that the 19F resonance of Trp346 is sensitive to changes in pH, consistent with crystallographic studies, and that receptor binding significantly stabilizes Trp346 to both pH and temperature. In addition, we provide evidence that suggests that resonances from tryptophans distant from the binding interface are also stabilized by the receptor. Our studies highlight the positive impact of receptor binding on protein stability and the use of 19F NMR in gaining insight into structural changes in a high-molecular weight protein. PMID:24387629

  18. MAGIC observations and multifrequency properties of the flat spectrum radio quasar 3C 279 in 2011

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Delgado Mendez, C.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Partini, S.; Persic, M.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Preziuso, S.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saggion, A.; Saito, T.; Saito, K.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamatescu, V.; Stamerra, A.; Steinbring, T.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Vogler, P.; Wagner, R. M.; Zandanel, F.; Zanin, R.

    2014-07-01

    Aims: We study the multifrequency emission and spectral properties of the quasar3C 279 aimed at identifying the radiation processes taking place in the source. Methods: We observed 3C 279 in very-high-energy (VHE, E> 100 GeV) γ-rays, with the MAGIC telescopes during 2011, for the first time in stereoscopic mode. We combined these measurements with observations at other energy bands: in high-energy (HE, E> 100 MeV) γ-rays from Fermi-LAT; in X-rays from RXTE; in the optical from the KVA telescope; and in the radio at 43 GHz, 37 GHz, and 15 GHz from the VLBA, Metsähovi, and OVRO radio telescopes - along with optical polarisation measurements from the KVA and Liverpool telescopes. We examined the corresponding light curves and broadband spectral energy distribution and we compared the multifrequency properties of 3C 279 at the epoch of the MAGIC observations with those inferred from historical observations. Results: During the MAGIC observations (2011 February 8 to April 11) 3C 279 was in a low state in optical, X-ray, and γ-rays. The MAGIC observations did not yield a significant detection. The derived upper limits are in agreement with the extrapolation of the HE γ-ray spectrum, corrected for EBL absorption, from Fermi-LAT. The second part of the MAGIC observations in 2011 was triggered by a high-activity state in the optical and γ-ray bands. During the optical outburst the optical electric vector position angle (EVPA) showed a rotation of ~180°. Unlike previous cases, there was no simultaneous rotation of the 43 GHz radio polarisation angle. No VHE γ-rays were detected by MAGIC, and the derived upper limits suggest the presence of a spectral break or curvature between the Fermi-LAT and MAGIC bands. The combined upper limits are the strongest derived to date for the source at VHE and below the level of the previously detected flux by a factor of ~2. Radiation models that include synchrotron and inverse Compton emissions match the optical to γ-ray data

  19. Origins of magic: review of genetic and epigenetic effects

    PubMed Central

    2007-01-01

    Objective To assess the evidence for a genetic basis to magic. Design Literature review. Setting Harry Potter novels of J K Rowling. Participants Muggles, witches, wizards, and squibs. Interventions Limited. Main outcome measures Family and twin studies, magical ability, and specific magical skills. Results Magic shows strong evidence of heritability, with familial aggregation and concordance in twins. Evidence suggests magical ability to be a quantitative trait. Specific magical skills, notably being able to speak to snakes, predict the future, and change hair colour, all seem heritable. Conclusions A multilocus model with a dominant gene for magic might exist, controlled epistatically by one or more loci, possibly recessive in nature. Magical enhancers regulating gene expressionmay be involved, combined with mutations at specific genes implicated in speech and hair colour such as FOXP2 and MCR1. PMID:18156238

  20. A Simple Parameterization of 3 x 3 Magic Squares

    ERIC Educational Resources Information Center

    Trenkler, Gotz; Schmidt, Karsten; Trenkler, Dietrich

    2012-01-01

    In this article a new parameterization of magic squares of order three is presented. This parameterization permits an easy computation of their inverses, eigenvalues, eigenvectors and adjoints. Some attention is paid to the Luoshu, one of the oldest magic squares.