%0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 1997 %T In vivo NMR and MRI using injection delivery of laser-polarized xenon %A Goodson, B. M. %A Song, Y. Q. %A Taylor, R. E. %A Schepkin, V. D. %A Brennan, K. M. %A Chingas, G. C. %A Budinger, T. F. %A Navon, G. %A Pines, A. %K humans %X

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo Xe-129 NMR/MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold.

%B Proceedings of the National Academy of Sciences of the United States of America %V 94 %P 14725-14729 %8 Dec 23 %@ 0027-8424 %G English %U ://WOS:000071182800090 %N 26 %M WOS:000071182800090 %! In vivo NMR and MRI using injection delivery of laser-polarized xenon %R Doi 10.1073/Pnas.94.26.14725 %0 Journal Article %J Journal of Chemical Physics %D 1996 %T Rotational diffusion measurements of suspended colloidal particles using two-dimensional exchange nuclear magnetic resonance %A Barrall, G. A. %A Schmidt-Rohr, K. %A Lee, Y. K. %A Landfester, K. %A Zimmermann, H. %A Chingas, G. C. %A Pines, A. %K scattering %X

We present here an experimental and theoretical study of the application of two-dimensional exchange nuclear magnetic resonance spectroscopy (NMR) to the investigation of the rotational diffusion of colloidal particles. The theoretical discussion includes the nature of the NMR frequency time-correlation function where the NMR interaction is represented by the chemical shift anisotropy (CSA). Time-correlation functions for the isotropic rotational diffusion of a suspension of colloidal particles containing single and multiple sites are derived in addition to time-correlation functions for the rotational diffusion of a suspension of symmetric top particles containing an isotropic distribution of a single CSA interaction. Simulations of two-dimensional exchange spectra for particles undergoing isotropic rotational diffusion are presented. We performed two-dimensional exchange NMR experiments on a colloidal suspension of spherical poly(methyl methacrylate) (PMMA) particles which were synthesized with a 20% enrichment in C-13 at the carbonyl site. Rotational diffusion time-correlation functions determined from the experimental exchange spectra are consistent with the composition of the colloidal suspension. Detailed explanations of the syntheses of the enriched methyl C-13-(carbonyl)-methacrylate monomer and the small quantities of 20% enriched C-13-(carbonyl)-poly(methyl methacrylate) microspheres used for this study are presented. (C) 1996 American Institute of Physics.

%B Journal of Chemical Physics %V 104 %P 509-520 %8 Jan 8 %@ 0021-9606 %G English %U ://WOS:A1996TN83700009 %N 2 %M WOS:A1996TN83700009 %! Rotational diffusion measurements of suspended colloidal particles using two-dimensional exchange nuclear magnetic resonance %R Doi 10.1063/1.470847 %0 Journal Article %J Journal of Magnetic Resonance Series A %D 1995 %T Spin-Polarized Xe-129 Gas Imaging of Materials %A Song, Y. Q. %A Gaede, H. C. %A Pietrass, T. %A Barrall, G. A. %A Chingas, G. C. %A Ayers, M. R. %A Pines, A. %K xenon %B Journal of Magnetic Resonance Series A %V 115 %P 127-130 %8 Jul %@ 1064-1858 %G English %U ://WOS:A1995RL47400017 %N 1 %M WOS:A1995RL47400017 %! Spin-Polarized Xe-129 Gas Imaging of Materials %R Doi 10.1006/Jmra.1995.1157 %0 Journal Article %J Journal of Chemical Physics %D 1994 %T 3-Dimensional Variable-Angle Nuclear-Magnetic-Resonance Exchange Spectroscopy without Rotor Axis Hopping %A Lee, Y. K. %A Emsley, L. %A Larsen, R. G. %A Schmidt-Rohr, K. %A Hong, M. %A Frydman, L. %A Chingas, G. C. %A Pines, A. %K distributions %X

Slow, large-amplitude chain motions play an important role in determining the macroscopic mechanical properties of polymers. Although such motions have been studied quantitatively by two-dimensional (2D) nuclear: magnetic resonance (NMR) exchange experiments, overlapping anisotropic patterns hamper spectral analysis, and limit applications. Variable angle correlation spectroscopy (VACSY) has proven useful in resolving such problems for rapidly spinning samples by separating anisotropic spectral patterns according to isotropic chemical shifts. In a previous study [J. Am. Chem. Sec. 115, 4825 (1993)], we described a three-dimensional (3D) NMR experiment that incorporates; the VACSY method and a hop of the rotor axis to correlate the isotropic chemical shifts to 2D anisotropic exchange patterns. The hop of the rotor axis, however, presents experimental difficulties and limits the range of motional rates that may be studied. We present in this paper a new 3D VACSY exchange experiment that obtains the same correlations without the need for the rotor axis hop. A series of 2D exchange spectra are recorded with the sample spinning at different rotation axis angles.' Then using the scaling of the anisotropic frequency at the different angles, we construct the data onto a 3D matrix so that a Fourier transformation directly yields the desired correlations. The technique is applied to C-13 exchange NMR to study the slow molecular motion of ordered isotactic polypropylene.

%B Journal of Chemical Physics %V 101 %P 1852-1864 %8 Aug 1 %@ 0021-9606 %G English %U ://WOS:A1994NY00200011 %N 3 %M WOS:A1994NY00200011 %! 3-Dimensional Variable-Angle Nuclear-Magnetic-Resonance Exchange Spectroscopy without Rotor Axis Hopping %R Doi 10.1063/1.467696 %0 Journal Article %J Journal of the American Chemical Society %D 1993 %T Variable-Angle 3-Dimensional Exchange Nuclear-Magnetic-Resonance Spectroscopy for the Study of Molecular-Motion in Complex Solids %A Frydman, L. %A Lee, Y. K. %A Emsley, L. %A Chingas, G. C. %A Pines, A. %K jumps %X

Although molecular motions are responsible for many of the macroscopic properties observed in solids, especially in polymers, methods for studying these processes in all but the simplest systems are scarce. In the present study we introduce a three-dimensional nuclear magnetic resonance experiment for characterizing ultraslow molecular motions in complex solid systems. The technique extracts dynamic information by resolving the two-dimensional exchange distributions that can be observed in spectra of static samples, according to the isotropic chemical shifts of individual molecular sites. These three-dimensional correlations are achieved by processing signals arising from a fast-spinning solid sample using two independent macroscopic axes of rotation as extraction parameters, an approach which becomes practical due to the simple scaling behavior of anisotropic chemical shifts with respect to the axis of sample rotation. The principles involved in this new spectroscopic technique are discussed, and the method is illustrated with an application to the analysis of motions in isotactic polypropylene.

%B Journal of the American Chemical Society %V 115 %P 4825-4829 %8 Jun 2 %@ 0002-7863 %G English %U ://WOS:A1993LF06200050 %N 11 %M WOS:A1993LF06200050 %! Variable-Angle 3-Dimensional Exchange Nuclear-Magnetic-Resonance Spectroscopy for the Study of Molecular-Motion in Complex Solids %R Doi 10.1021/Ja00064a050 %0 Journal Article %J Israel Journal of Chemistry %D 1992 %T Correlation of Isotropic and Anisotropic Chemical-Shifts in Solids by 2-Dimensional Variable-Angle-Spinning Nmr %A Frydman, L. %A Chingas, G. C. %A Lee, Y. K. %A Grandinetti, P. J. %A Eastman, M. A. %A Barrall, G. A. %A Pines, A. %K magic-angle %X

We describe a new solid-state nuclear magnetic resonance (NMR) technique for correlating anisotropic and isotropic chemical shifts in powdered samples. Two-dimensional (2D) NMR spectra are obtained by processing signals acquired in independent experiments for different angles between the sample spinning axis and the Zeeman magnetic field. This 2D NMR approach can therefore resolve individual static anisotropic lineshapes according to their isotropic chemical shift frequencies, without use of sudden mechanical motions or multiple-pulse irradiation schemes. Applications of the technique are illustrated with an analysis of the chemical shift anisotropy for the eight distinct C-13 sites in tyrosine.

%B Israel Journal of Chemistry %V 32 %P 161-164 %@ 0021-2148 %G English %U ://WOS:A1992KT51700005 %N 2-3 %M WOS:A1992KT51700005 %! Correlation of Isotropic and Anisotropic Chemical-Shifts in Solids by 2-Dimensional Variable-Angle-Spinning Nmr %0 Journal Article %J Journal of Chemical Physics %D 1992 %T Variable-Angle Correlation Spectroscopy in Solid-State Nuclear-Magnetic-Resonance %A Frydman, L. %A Chingas, G. C. %A Lee, Y. K. %A Grandinetti, P. J. %A Eastman, M. A. %A Barrall, G. A. %A Pines, A. %K axis %X

We describe here a new solid-state nuclear-magnetic-resonance (NMR) experiment for correlating anisotropic and isotropic chemical shifts of inequivalent nuclei in powdered samples. Spectra are obtained by processing signals arising from a spinning sample, acquired in independent experiments as a function of the angle between the axis of macroscopic rotation and the external magnetic field. This is in contrast to previously proposed techniques, which were based on sudden mechanical flippings or multiple-pulse sequences. We show that the time evolution of variable-angle-spinning signals is determined by a distribution relating the isotropic frequencies of the spins with their corresponding chemical shift anisotropies. Fourier transformation of these data therefore affords a two-dimensional NMR spectrum, in which line shapes of isotropic and anisotropic interactions are correlated. Theoretical and experimental considerations involved in the extraction of this spectral information are discussed, and the technique is illustrated by an analysis of C-13 NMR anisotropy in glycine, cysteine, and p-anisic acid.

%B Journal of Chemical Physics %V 97 %P 4800-4808 %8 Oct 1 %@ 0021-9606 %G English %U ://WOS:A1992JR33800022 %N 7 %M WOS:A1992JR33800022 %! Variable-Angle Correlation Spectroscopy in Solid-State Nuclear-Magnetic-Resonance %R Doi 10.1063/1.463860 %0 Journal Article %J Review of Scientific Instruments %D 1991 %T Nmr Probe for Dynamic-Angle Spinning %A Mueller, K. T. %A Chingas, G. C. %A Pines, A. %K minerals %X

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

%B Review of Scientific Instruments %V 62 %P 1445-1452 %8 Jun %@ 0034-6748 %G English %U ://WOS:A1991FP31200011 %N 6 %M WOS:A1991FP31200011 %! Nmr Probe for Dynamic-Angle Spinning %R Doi 10.1063/1.1142465 %0 Journal Article %J Journal of Magnetic Resonance %D 1990 %T Dynamic-Angle Spinning of Quadrupolar Nuclei %A Mueller, K. T. %A Sun, B. Q. %A Chingas, G. C. %A Zwanziger, J. W. %A Terao, T. %A Pines, A. %B Journal of Magnetic Resonance %V 86 %P 470-487 %8 Feb 15 %@ 0022-2364 %G English %U ://WOS:A1990CU52500003 %N 3 %M WOS:A1990CU52500003 %! Dynamic-Angle Spinning of Quadrupolar Nuclei %R Doi 10.1016/0022-2364(90)90025-5 %0 Journal Article %J Review of Scientific Instruments %D 1990 %T A Fast, Stable Quadrature Phase Generator for Multiple-Pulse Nmr %A Shykind, D. N. %A Chingas, G. C. %A Pines, A. %A Shaka, A. J. %B Review of Scientific Instruments %V 61 %P 1474-1479 %8 May %@ 0034-6748 %G English %U ://WOS:A1990DC42500016 %N 5 %M WOS:A1990DC42500016 %! A Fast, Stable Quadrature Phase Generator for Multiple-Pulse Nmr %R Doi 10.1063/1.1141155 %0 Journal Article %J Journal of Magnetic Resonance %D 1988 %T Multiple-Pulse Sequences for Precise Transmitter Phase Alignment %A Shaka, A. J. %A Shykind, D. N. %A Chingas, G. C. %A Pines, A. %B Journal of Magnetic Resonance %V 80 %P 96-111 %8 Oct 15 %@ 0022-2364 %G English %U ://WOS:A1988Q618700008 %N 1 %M WOS:A1988Q618700008 %! Multiple-Pulse Sequences for Precise Transmitter Phase Alignment %R Doi 10.1016/0022-2364(88)90060-1 %0 Journal Article %J Molecular Physics %D 1987 %T Berry Phase in Magnetic-Resonance %A Suter, D. %A Chingas, G. C. %A Harris, R. A. %A Pines, A. %B Molecular Physics %V 61 %P 1327-1340 %8 Aug 20 %@ 0026-8976 %G English %U ://WOS:A1987K215400001 %N 6 %M WOS:A1987K215400001 %! Berry Phase in Magnetic-Resonance %R Doi 10.1080/00268978700101831