Co-reporter:
Magnetic Resonance in Chemistry 2017 Volume 55(Issue 4) pp:312-317
Publication Date(Web):2017/04/01
DOI:10.1002/mrc.4529
Reindeer skin clothing has been an essential component in the lives of indigenous people of the arctic and sub-arctic regions, keeping them warm during harsh winters. However, the skin processing technology, which often conveys the history and tradition of the indigenous group, has not been well documented. In this study, NMR spectra and relaxation behaviors of reindeer skin samples treated with a variety of vegetable tannin extracts, oils and fatty substances are studied and compared. With the assistance of principal component analysis (PCA), one can recognize patterns and identify groupings of differently treated samples. These methods could be important aids in efforts to conserve museum leather artifacts with unknown treatment methods and in the analysis of reindeer skin tanning processes. Copyright © 2016 John Wiley & Sons, Ltd.
Co-reporter:B. Kharkov, X. Duan, J.W. Canary, A. Jerschow
Journal of Magnetic Resonance 2017 Volume 284(Volume 284) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jmr.2017.09.005
•The effect of convection and B1 inhomogeneity on singlet lifetime measurements is shown.•A thermal convection model is shown to explain the experimental results.•Sample spinning can alleviate convection artifacts, but also sample confinement, and highly inhomogeneity-compensated pulses.Nuclear spin singlet lifetimes can often exceed the T1 length scales by a large factor. This property makes them suitable for polarization storage. The measurement of such long lifetimes itself can become challenging due to the influence of even very weak relaxation mechanisms. Here we show that a judicious choice of the singlet-to-triplet conversion method is highly important in order to achieve reliable singlet relaxation measurements. In particular, we identify thermal convection, in connection with B1 field gradients, as a significant apparent decay mechanism, which limits the ability to measure the true singlet state lifetimes. Highly B1-compensated broadband singlet excitation/detection sequences are shown to minimize the influence of macroscopic molecular motion and B1 inhomogeneity.Download high-res image (68KB)Download full-size image
Co-reporter:Evgeny Nimerovsky, Andrew J. Ilott, Alexej Jerschow
Journal of Magnetic Resonance 2016 Volume 272() pp:129-140
Publication Date(Web):November 2016
DOI:10.1016/j.jmr.2016.09.007
•We present a new method for the selective excitation of slow-motion spins 3/2.•The method performs well in the low-power regime as well as in the presence of inhomogeneities.•The experiment is described analytically and in numerical simulations.•The method is more efficient than triple quantum filtering.Triple Quantum Filters (TQFs) are frequently used for the selection of bi-exponentially relaxing spin 3/2 nuclei (in particular 23Na) in ordered environments, such as biological tissues. These methods provide an excellent selection of slow-motion spins, but their sensitivity is generally low, and coherence selection requirements may lead to long experiments when applied in vivo. Alternative methods, such as 2P DIM, have demonstrated that the sensitivities of the signals from bi-exponentially relaxing sodium can be significantly increased using strategies other than TQFs. A shortcoming of the 2P DIM method is its strong dependence on B0 inhomogeneities. We describe here a method, which is sensitive to the slow-motion regime, while the signal from spins in the fast-motion regime is suppressed. This method is shown to be more effective than TQFs, requires minimal phase cycling for the suppression of the influence of rf inhomogeneity, and has less dependence on resonance offsets and B0-inhomogeneity than 2P DIM.
Co-reporter:Weiqi Yang, Jae-Seung Lee, Boris Kharkov, Andrew J. Ilott, Alexej Jerschow
Journal of Magnetic Resonance 2016 Volume 272() pp:61-67
Publication Date(Web):November 2016
DOI:10.1016/j.jmr.2016.08.013
•A faster, 2D slice-selective imaging method for the rigid material is proposed.•This method provides greater detail compared to UTE and spin echo method.•High SNR is achieved in both the high and low power regimes.One of the major challenges in using magnetic resonance imaging (MRI) to study immobile samples, such as solid materials or rigid tissues like bone or ligaments, is that the images appear dark due to these samples’ short-lived signals. Although it is well known that narrowband signals can be excited in inhomogeneously-broadened lines, it is less well known that similar effects can be observed in dipolar-broadened systems. These long-lived signals have not been used much, mainly because their description frequently does not match intuition. While 3D imaging with these signals has previously been reported, here we focus on the demonstration of faster, 2D slice-selective imaging. The faster imaging provides more flexibility for visualizing these rigid objects. We also focus on the frequently-encountered regime wherein the maximum power achievable for rf pulses is significantly weaker than the linewidth. This regime is typically encountered in clinical MRI scans or large volume setups. When compared to UTE and conventional slice-selective spin echo methods, this technique provides better representations of the sample considered here (an eraser sample), and higher signal-to-noise ratios than spin-echo techniques in both the high and low power regimes.AAA
Co-reporter:Andrew J. Ilott;Mohaddese Mohammadi;Hee Jung Chang;Clare P. Grey
PNAS 2016 Volume 113 (Issue 39 ) pp:10779-10784
Publication Date(Web):2016-09-27
DOI:10.1073/pnas.1607903113
Lithium metal is a promising anode material for Li-ion batteries due to its high theoretical specific capacity and low potential.
The growth of dendrites is a major barrier to the development of high capacity, rechargeable Li batteries with lithium metal
anodes, and hence, significant efforts have been undertaken to develop new electrolytes and separator materials that can prevent
this process or promote smooth deposits at the anode. Central to these goals, and to the task of understanding the conditions
that initiate and propagate dendrite growth, is the development of analytical and nondestructive techniques that can be applied
in situ to functioning batteries. MRI has recently been demonstrated to provide noninvasive imaging methodology that can detect
and localize microstructure buildup. However, until now, monitoring dendrite growth by MRI has been limited to observing the
relatively insensitive metal nucleus directly, thus restricting the temporal and spatial resolution and requiring special
hardware and acquisition modes. Here, we present an alternative approach to detect a broad class of metallic dendrite growth
via the dendrites’ indirect effects on the surrounding electrolyte, allowing for the application of fast 3D 1H MRI experiments with high resolution. We use these experiments to reconstruct 3D images of growing Li dendrites from MRI,
revealing details about the growth rate and fractal behavior. Radiofrequency and static magnetic field calculations are used
alongside the images to quantify the amount of the growing structures.
Co-reporter:Hee Jung Chang; Andrew J. Ilott; Nicole M. Trease; Mohaddese Mohammadi; Alexej Jerschow;Clare P. Grey
Journal of the American Chemical Society 2015 Volume 137(Issue 48) pp:15209-15216
Publication Date(Web):November 2, 2015
DOI:10.1021/jacs.5b09385
Lithium dendrite growth in lithium ion and lithium rechargeable batteries is associated with severe safety concerns. To overcome these problems, a fundamental understanding of the growth mechanism of dendrites under working conditions is needed. In this work, in situ 7Li magnetic resonance (MRI) is performed on both the electrolyte and lithium metal electrodes in symmetric lithium cells, allowing the behavior of the electrolyte concentration gradient to be studied and correlated with the type and rate of microstructure growth on the Li metal electrode. For this purpose, chemical shift (CS) imaging of the metal electrodes is a particularly sensitive diagnostic method, enabling a clear distinction to be made between different types of microstructural growth occurring at the electrode surface and the eventual dendrite growth between the electrodes. The CS imaging shows that mossy types of microstructure grow close to the surface of the anode from the beginning of charge in every cell studied, while dendritic growth is triggered much later. Simple metrics have been developed to interpret the MRI data sets and to compare results from a series of cells charged at different current densities. The results show that at high charge rates, there is a strong correlation between the onset time of dendrite growth and the local depletion of the electrolyte at the surface of the electrode observed both experimentally and predicted theoretical (via the Sand’s time model). A separate mechanism of dendrite growth is observed at low currents, which is not governed by salt depletion in the bulk liquid electrolyte. The MRI approach presented here allows the rate and nature of a process that occurs in the solid electrode to be correlated with the concentrations of components in the electrolyte.
Co-reporter:Lizheng Zhu, Eleonora Del Federico, Andrew J. Ilott, Torunn Klokkernes, Cindie Kehlet, and Alexej Jerschow
Analytical Chemistry 2015 Volume 87(Issue 7) pp:3820
Publication Date(Web):February 26, 2015
DOI:10.1021/ac504474e
The study of arctic or subarctic indigenous skin clothing material, known for its design and ability to keep the body warm, provides information about the tanning materials and techniques. The study also provides clues about the culture that created it, since tanning processes are often specific to certain indigenous groups. Untreated skin samples and samples treated with willow (Salix sp) bark extract and cod liver oil are compared in this study using both MRI and unilateral NMR techniques. The two types of samples show different proton spatial distributions and different relaxation times, which may also provide information about the tanning technique and aging behavior.
Co-reporter:Y. Zhang, K. Basu, J. W. Canary and A. Jerschow
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 37) pp:24370-24375
Publication Date(Web):19 Aug 2015
DOI:10.1039/C5CP03716F
Hyperpolarized singlet states provide the opportunity for polarization storage over periods significantly longer than T1. Here, we show how the singlet state in a chemically equivalent proton spin system can be revealed by a weak power spin-lock. This procedure allowed the measurement of the lifetimes of the singlet state in protic solvents. The contributions of different intra- and intermolecular relaxation mechanisms to singlet lifetimes are investigated with this procedure.
Co-reporter:Guillaume Madelin, Jae-Seung Lee, Ravinder R. Regatte, Alexej Jerschow
Progress in Nuclear Magnetic Resonance Spectroscopy 2014 Volume 79() pp:14-47
Publication Date(Web):May 2014
DOI:10.1016/j.pnmrs.2014.02.001
•Sodium MRI gives new biochemical information as a complement to proton MRI.•Sodium MRI is sensitive to loss of ion homeostasis and cell viability.•Sodium ions are sensitive to their environment through the quadrupolar relaxation and the residual quadrupolar interaction.•Sodium MRI can be applied to all parts of the body for assessing diseases.Sodium NMR spectroscopy and MRI have become popular in recent years through the increased availability of high-field MRI scanners, advanced scanner hardware and improved methodology. Sodium MRI is being evaluated for stroke and tumor detection, for breast cancer studies, and for the assessment of osteoarthritis and muscle and kidney functions, to name just a few. In this article, we aim to present an up-to-date review of the theoretical background, the methodology, the challenges, limitations, and current and potential new applications of sodium MRI.
Co-reporter:Yuning Zhang;Pei Che Soon; Alexej Jerschow; James W. Canary
Angewandte Chemie 2014 Volume 126( Issue 13) pp:3464-3467
Publication Date(Web):
DOI:10.1002/ange.201310284
Abstract
Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) have become important techniques in many research areas. One major limitation is the relatively low sensitivity of these methods, which recently has been addressed by hyperpolarization. However, once hyperpolarization is imparted on a molecule, the magnetization typically decays within relatively short times. Singlet states are well isolated from the environment, such that they acquire long lifetimes. We describe herein a model reaction for read-out of a hyperpolarized long-lived state in dimethyl maleate using thiol conjugate addition. This type of reaction could lend itself to monitoring oxidative stress or hypoxia by sensitive detection of thiols. Similar reactions could be used in biosensors or assays that exploit molecular switching. Singlet lifetimes of about 4.7 min for 1H spins in [D4]MeOH are seen in this system.
Co-reporter:Yuning Zhang;Pei Che Soon; Alexej Jerschow; James W. Canary
Angewandte Chemie International Edition 2014 Volume 53( Issue 13) pp:3396-3399
Publication Date(Web):
DOI:10.1002/anie.201310284
Abstract
Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) have become important techniques in many research areas. One major limitation is the relatively low sensitivity of these methods, which recently has been addressed by hyperpolarization. However, once hyperpolarization is imparted on a molecule, the magnetization typically decays within relatively short times. Singlet states are well isolated from the environment, such that they acquire long lifetimes. We describe herein a model reaction for read-out of a hyperpolarized long-lived state in dimethyl maleate using thiol conjugate addition. This type of reaction could lend itself to monitoring oxidative stress or hypoxia by sensitive detection of thiols. Similar reactions could be used in biosensors or assays that exploit molecular switching. Singlet lifetimes of about 4.7 min for 1H spins in [D4]MeOH are seen in this system.
Co-reporter:Andrew J. Ilott, S. Chandrashekar, Andreas Klöckner, Hee Jung Chang, Nicole M. Trease, Clare P. Grey, Leslie Greengard, Alexej Jerschow
Journal of Magnetic Resonance 2014 245() pp: 143-149
Publication Date(Web):1 August 2014
DOI:10.1016/j.jmr.2014.06.013
•Sample-rf field orientation effects are explored for MR experiments on bulk metals.•Boundary integral equation calculations are performed to calculate the rf field inside and outside of Lithium metal.•The calculation results are in excellent agreement with experimental MRI results.•The metal cannot be uniformly excited at any relative rf field orientation.•Spatial selectivity can be achieved by judiciously orienting a metal sample.While experiments on metals have been performed since the early days of NMR (and DNP), the use of bulk metal is normally avoided. Instead, often powders have been used in combination with low fields, so that skin depth effects could be neglected. Another complicating factor of acquiring NMR spectra or MRI images of bulk metal is the strong signal dependence on the orientation between the sample and the radio frequency (rf) coil, leading to non-intuitive image distortions and inaccurate quantification. Such factors are particularly important for NMR and MRI of batteries and other electrochemical devices. Here, we show results from a systematic study combining rf field calculations with experimental MRI of 7Li metal to visualize skin depth effects directly and to analyze the rf field orientation effect on MRI of bulk metal. It is shown that a certain degree of selectivity can be achieved for particular faces of the metal, simply based on the orientation of the sample. By combining rf field calculations with bulk magnetic susceptibility calculations accurate NMR spectra can be obtained from first principles. Such analyses will become valuable in many applications involving battery systems, but also metals, in general.Download high-res image (168KB)Download full-size image
Co-reporter:Pei Che Soon, Xiang Xu, Boyang Zhang, Francesca Gruppi, James W. Canary and Alexej Jerschow
Chemical Communications 2013 vol. 49(Issue 46) pp:5304-5306
Publication Date(Web):23 Apr 2013
DOI:10.1039/C3CC40426A
Several important neurotransmitter precursors were hyperpolarized via homogeneous hydrogenation with parahydrogen. Polarization enhancement was achieved for 1H and 13C spins by several orders of magnitude compared to thermal spectra. Such large signal enhancements of these molecules could facilitate neurotransmitter studies.
Co-reporter:Dr. Xiang Xu;Dr. Jae-Seung Lee; Alexej Jerschow
Angewandte Chemie International Edition 2013 Volume 52( Issue 32) pp:8281-8284
Publication Date(Web):
DOI:10.1002/anie.201303255
Co-reporter:Boyang Zhang, Jae-Seung Lee, Anatoly Khitrin, Alexej Jerschow
Journal of Magnetic Resonance 2013 231() pp: 1-4
Publication Date(Web):
DOI:10.1016/j.jmr.2013.03.002
Co-reporter:Dr. Xiang Xu;Dr. Jae-Seung Lee; Alexej Jerschow
Angewandte Chemie 2013 Volume 125( Issue 32) pp:8439-8442
Publication Date(Web):
DOI:10.1002/ange.201303255
Co-reporter:Dr. Francesca Gruppi;Xiang Xu;Boyang Zhang;Dr. Joel A. Tang; Alexej Jerschow; James W. Canary
Angewandte Chemie 2012 Volume 124( Issue 47) pp:11957-11960
Publication Date(Web):
DOI:10.1002/ange.201204403
Co-reporter:Dr. Francesca Gruppi;Xiang Xu;Boyang Zhang;Dr. Joel A. Tang; Alexej Jerschow; James W. Canary
Angewandte Chemie International Edition 2012 Volume 51( Issue 47) pp:11787-11790
Publication Date(Web):
DOI:10.1002/anie.201204403
Co-reporter:Jae-Seung Lee, Ravinder R. Regatte, Alexej Jerschow
Journal of Magnetic Resonance 2012 215() pp: 56-63
Publication Date(Web):
DOI:10.1016/j.jmr.2011.12.012
Co-reporter:Uzi Eliav, S. Chandra shekar, Wen Ling, Gil Navon, Alexej Jerschow
Journal of Magnetic Resonance 2012 216() pp: 114-120
Publication Date(Web):
DOI:10.1016/j.jmr.2012.01.012
Co-reporter:Joel A. Tang, Francesca Gruppi, Roman Fleysher, Daniel K. Sodickson, James W. Canary and Alexej Jerschow
Chemical Communications 2011 vol. 47(Issue 3) pp:958-960
Publication Date(Web):15 Nov 2010
DOI:10.1039/C0CC03421E
A system that provides a sustained hyperpolarized 1H NMR signal in an aqueous medium is reported. The enhanced signal lasts much longer than typical 1H T1 values, uncovering new possibilities for implementing hyperpolarized 1H NMR/MRI experiments or performing kinetics studies that would not otherwise be detectable.
Co-reporter:Guillaume Madelin, Jae-Seung Lee, Souheil Inati, Alexej Jerschow, Ravinder R. Regatte
Journal of Magnetic Resonance 2010 Volume 207(Issue 1) pp:42-52
Publication Date(Web):November 2010
DOI:10.1016/j.jmr.2010.08.003
The loss of proteoglycans (PG) in the articular cartilage is an early signature of osteoarthritis (OA). The ensuing changes in the fixed charge density in the cartilage can be directly linked to sodium concentration via charge balance. Sodium ions in the knee joint appear in two pools: in the synovial fluids or joint effusion where the ions are in free motion and bound within the cartilage tissue where the Na+ ions have a restricted motion. The ions in these two compartments have therefore different T1 and T2 relaxation times. The purpose of this study is to demonstrate the feasibility of a fluid-suppressed 3D ultrashort TE radial sodium sequence by implementing an inversion recovery (IR) preparation of the magnetization at 7T. This method could allow a more accurate and more sensitive quantification of loss of PG in patients with OA. It is shown that adiabatic pulses offer significantly improved performance in terms of robustness to B1 and B0 inhomogeneities when compared to the hard pulse sequence. Power deposition considerations further pose a limit to the RF inversion power, and we demonstrate in simulations and experiments how a practical compromise can be struck between clean suppression of fluid signals and power deposition levels. Two IR sequences with different types of inversion pulses (a rectangular pulse and an adiabatic pulse) were tested on a liquid phantom, ex vivo on a human knee cadaver and then in vivo on five healthy volunteers, with a (Nyquist) resolution of ∼3.6 mm and a signal-to-noise ratio of ∼30 in cartilage without IR and ∼20 with IR. Due to specific absorption rate limitations, the total acquisition time was ∼17 min for the 3D radial sequence without inversion or with the rectangular IR, and 24:30 min for the adiabatic IR sequence. It is shown that the adiabatic IR sequence generates a more uniform fluid suppression over the whole sample than the rectangular IR sequence.
Co-reporter:Jae-Seung Lee, Ravinder R. Regatte, Alexej Jerschow
Chemical Physics Letters 2010 Volume 494(4–6) pp:331-336
Publication Date(Web):19 July 2010
DOI:10.1016/j.cplett.2010.06.019
Abstract
Sodium ions in tissues and organs may experience motion on a variety of timescales, leading to NMR relaxation effects with quadrupolar coupling as the primary mechanism. The various effects that this fluctuating interaction has on spin dynamics can be exploited for distinguishing slow sodium ions from fast ones. Techniques such as triple-quantum filtering have been used for this purpose in the past. In this work we present optimal pulses which significantly improve the selectivity towards slow-tumbling sodium. These pulses can also be modified for robustness against magnetic field inhomogeneities, and could hence also become useful as MRI contrast methods.
Co-reporter:Patrick Giraudeau, Norbert Müller, Alexej Jerschow, Lucio Frydman
Chemical Physics Letters 2010 Volume 489(1–3) pp:107-112
Publication Date(Web):1 April 2010
DOI:10.1016/j.cplett.2010.02.026
Abstract
Noise measurements of nuclear spin systems using a tuned circuit can reveal the signatures of two different phenomena: Thermal circuit noise absorbed by the spin system, and nuclear spin-noise leading to tiny fluctuating magnetization components. Polarization enhancement can increase the observed noise amplitudes due to an enlarged coupling with the reception circuit. In this work we explore the detection of noise in 1H NMR of liquid water samples whose spin alignment is enhanced via ex situ dynamic nuclear polarization. A number of ancillary phenomena related to this kind of experiments are also documented.
Co-reporter:Joel A. Tang
Magnetic Resonance in Chemistry 2010 Volume 48( Issue 10) pp:763-770
Publication Date(Web):
DOI:10.1002/mrc.2651
Abstract
Sensitivity enhancement by the use of inductively coupled milli- and microcoils has been demonstrated in solid-state as well as liquid-state NMR. In this work, we discuss the practical aspects of using inductively coupled solenoid coils of different sizes in a liquid-state NMR spectrometer. The sensitivity and resolution enhancements from these resonant coils, with sizes ranging between 3.0 and 0.75 mm i.d., are measured for 23Na single-pulse and multidimensional imaging experiments and compared to the results obtained with the conventional liquids NMR 5.0-mm saddle coil. Enhancements in voxel-based sensitivity (SNR per √scans) were measured in multidimensional MR images and were found to be as large as 20.4 with the 0.75-mm coil. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Jae-Seung Lee, Ravinder R. Regatte, Alexej Jerschow
Journal of Magnetic Resonance 2009 Volume 200(Issue 1) pp:126-129
Publication Date(Web):September 2009
DOI:10.1016/j.jmr.2009.06.015
A simple pulse sequence, derived from the shaped pulse optimally exciting the central transition of a spin 3/2, can be used to selectively detect ordered sodium with a given quadrupolar coupling. The pulse sequence consists of two pulses with opposite phases and separated by a delay, called a quadrupolar jump-and-return (QJR) sequence. This QJR sequence is tested with a phantom made of sodium ions in bacteriophage and in aqueous solution and its feasibility for contrast modification based on the quadrupolar coupling is demonstrated.
Co-reporter:Peng Rong, Ravinder R. Regatte, Alexej Jerschow
Journal of Magnetic Resonance 2008 Volume 193(Issue 2) pp:207-209
Publication Date(Web):August 2008
DOI:10.1016/j.jmr.2008.04.036
Monitoring the sodium concentration in vivo using 23Na MRI can be an important tool for assessing the onset of tissue disorders. Practical clinical 23Na MRI methods furthermore often do not allow one to use sufficiently small voxel sizes such that only the tissue of interest is seen, but a large signal contamination can arise from sodium in synovial fluid. Here we demonstrate that applying an inversion recovery (IR) technique allows one to distinctly select either the cartilage-bound or the free sodium for visualization in an image. The results are validated both ex vivo and in vivo.
Co-reporter:Wen Ling, Uzi Eliav, Gil Navon, Alexej Jerschow
Journal of Magnetic Resonance 2008 Volume 194(Issue 1) pp:29-32
Publication Date(Web):September 2008
DOI:10.1016/j.jmr.2008.05.026
A number of contrast enhancement effects based on the use of intermolecular multiple-quantum coherences, or distant dipolar field effects are known. This phenomenon is characterized by the dependence on the mth power of the initial magnetization (where m is the coherence order used). In this paper, we describe the contrast enhancement based on chemical exchange saturation transfer and NOE, which is achieved by the use of intermolecular double-quantum coherences (iDQC). The method was validated using clinically relevant systems based on glycosaminoglycans and a sample of cartilage tissue, showing that the CEST contrast, as well as, NOE are enhanced by iDQC.
Co-reporter:Wen Ling;Ravinder R. Regatte;Gil Navon
PNAS 2008 Volume 105 (Issue 7 ) pp:2266-2270
Publication Date(Web):2008-02-19
DOI:10.1073/pnas.0707666105
Glycosaminogycans (GAGs) are involved in numerous vital functions in the human body. Mapping the GAG concentration in vivo is desirable for the diagnosis and monitoring of a number of diseases such as osteoarthritis, which affects millions of individuals.
GAG loss in cartilage is typically an initiating event in osteoarthritis. Another widespread pathology related to GAG is intervertebral
disk degeneration. Currently existing techniques for GAG monitoring, such as delayed gadolinium-enhanced MRI contrast (dGEMRIC),
T
1
ρ, and 23Na MRI, have some practical limitations. We show that by exploiting the exchangeable protons of GAG one may directly measure
the localized GAG concentration in vivo with high sensitivity and therefore obtain a powerful diagnostic MRI method.
Co-reporter:Wen Ling;Ravinder R. Regatte;Mark E. Schweitzer
Magnetic Resonance in Medicine 2006 Volume 56(Issue 5) pp:1151-1155
Publication Date(Web):6 OCT 2006
DOI:10.1002/mrm.21062
The onset of cartilage tissue disorders can be characterized by a loss of proteoglycans (PGs) and diagnosed by contrast-enhanced proton (1H) MRI techniques, as well as sodium MRI. The behavior of sodium located in anisotropic environments, is examined as a function of cartilage degeneration. PGs are proteolytically depleted from the cartilage samples, which gives rise to a decrease of the ordered sodium content. More surprisingly, however, the residual quadrupolar couplings are shown to increase with increasing depletion levels. Since the residual quadrupolar couplings are intimately related to local order and anisotropic motion, measuring their distribution in cartilage may provide insight into the structural changes that occur within the tissue upon degradation. In this study relatively mild orientational dependence of the couplings was found. Little or no free sodium was observed in the cartilage specimens under study. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc.
Co-reporter:Norbert Müller;
Proceedings of the National Academy of Sciences 2006 103(18) pp:6790-6792
Publication Date(Web):April 24, 2006
DOI:10.1073/pnas.0601743103
NMR images were obtained from the proton spin noise signals of a water-containing phantom, which was placed in the highly
tuned, low-noise resonant circuit of a cryogenically cooled NMR probe in the presence of systematically varied magnetic field
gradients. The spatially resolved proton spin density was obtained from the raw signal by a modified projection–reconstruction
protocol. Although spin noise imaging is inherently less sensitive than conventional magnetic resonance imaging, it affords
an entirely noninvasive visualization of the interior of opaque objects or subjects. Thus, tomography becomes possible even
when neither x-ray nor radio frequency radiation can be applied for technical or safety reasons.
Co-reporter:Alexej Jerschow
Progress in Nuclear Magnetic Resonance Spectroscopy 2005 Volume 46(Issue 1) pp:63-78
Publication Date(Web):17 March 2005
DOI:10.1016/j.pnmrs.2004.12.001
Co-reporter:David D. Laws Dr.;Hans-Marcus L. Bitter Dr. Dr.
Angewandte Chemie International Edition 2002 Volume 41(Issue 17) pp:
Publication Date(Web):30 AUG 2002
DOI:10.1002/1521-3773(20020902)41:17<3096::AID-ANIE3096>3.0.CO;2-X
Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
Co-reporter:David D. Laws Dr.;Hans-Marcus L. Bitter Dr. Dr.
Angewandte Chemie 2002 Volume 114(Issue 17) pp:
Publication Date(Web):30 AUG 2002
DOI:10.1002/1521-3757(20020902)114:17<3224::AID-ANGE3224>3.0.CO;2-C
In den vergangenen Jahrzehnten hat sich die NMR-Spektroskopie zu einem unverzichtbaren Werkzeug für die chemische Analyse, Strukturaufklärung und Untersuchung dynamischer Prozesse in organischen, anorganischen und biologischen Systemen entwickelt. Sie ist die Methode der Wahl für eine Vielzahl von Anwendungen, von der Charakterisierung von Syntheseprodukten bis hin zur Untersuchung der molekularen Struktur von Katalysatoren, Polymeren und Proteinen. Speziell die NMR-Spektroskopie an Festkörpern hat sich dabei zu einer leistungsfähigen Methode zur Untersuchung fester Proben und Materialien entwickelt. Dieser Aufsatz beschreibt einige der Konzepte und Methoden der Festkörper-NMR-Spektroskopie wie Kreuzpolarisation, Magic-Angle-Spinning, Multipulssequenzen, homo- und heteronucleare Ent- und Wiedereinkopplung, Mehrquantenspektroskopie und Dynamic-Angle-Spinning sowie deren Anwendung in der Strukturaufklärung. Moderne Festkörper-NMR-Techniken ermöglichen nicht nur die Aufnahme von Spektren mit „flüssigkeitsähnlicher“ Auflösung, sie nutzen darüber hinaus anisotrope Wechselwirkungen, die bei Proben in flüssiger Phase nicht zur Verfügung stehen. Vor diesem Hintergrund soll hier die gegenwärtige und zukünftige Bedeutung der Festkörper-NMR-Spektroskopie für die Chemie unterstrichen werden.
Co-reporter:Joel A. Tang, Francesca Gruppi, Roman Fleysher, Daniel K. Sodickson, James W. Canary and Alexej Jerschow
Chemical Communications 2011 - vol. 47(Issue 3) pp:NaN960-960
Publication Date(Web):2010/11/15
DOI:10.1039/C0CC03421E
A system that provides a sustained hyperpolarized 1H NMR signal in an aqueous medium is reported. The enhanced signal lasts much longer than typical 1H T1 values, uncovering new possibilities for implementing hyperpolarized 1H NMR/MRI experiments or performing kinetics studies that would not otherwise be detectable.
Co-reporter:Pei Che Soon, Xiang Xu, Boyang Zhang, Francesca Gruppi, James W. Canary and Alexej Jerschow
Chemical Communications 2013 - vol. 49(Issue 46) pp:NaN5306-5306
Publication Date(Web):2013/04/23
DOI:10.1039/C3CC40426A
Several important neurotransmitter precursors were hyperpolarized via homogeneous hydrogenation with parahydrogen. Polarization enhancement was achieved for 1H and 13C spins by several orders of magnitude compared to thermal spectra. Such large signal enhancements of these molecules could facilitate neurotransmitter studies.
Co-reporter:Y. Zhang, K. Basu, J. W. Canary and A. Jerschow
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 37) pp:NaN24375-24375
Publication Date(Web):2015/08/19
DOI:10.1039/C5CP03716F
Hyperpolarized singlet states provide the opportunity for polarization storage over periods significantly longer than T1. Here, we show how the singlet state in a chemically equivalent proton spin system can be revealed by a weak power spin-lock. This procedure allowed the measurement of the lifetimes of the singlet state in protic solvents. The contributions of different intra- and intermolecular relaxation mechanisms to singlet lifetimes are investigated with this procedure.
.jpg)
![L-Alaninamide, N-[(7R,8S)-2-carboxy-7,8-dihydro-8-hydroxy-4-[(1S)-1-hydroxyethyl]-7-quinolinyl]-L-isoleucyl-L-alanyl-2,3-didehydroalanyl-N-](/data/chemimg/1964300/75524-61-7.png)
![L-Alaninamide, N-[(7R,8S)-2-carboxy-7,8-dihydro-8-hydroxy-4-[(1S)-1-hydroxyethyl]-7-quinolinyl]-L-isoleucyl-L-alanyl-2,3-didehydroalanyl-N-](/data/chemimg/1964300/75524-61-7_b.png)
